JPH03193995A - Production of cast coated paper - Google Patents

Abstract

PURPOSE:To produce the subject coated paper having largely improved steam permeability at a high speed by employing base paper obtained by adjusting so as to keep the yield of a filler and fine paper fibers to a value of >= a specific value in a paper-making process. CONSTITUTION:When a coating layer consisting mainly of a pigment and an adhesive is disposed on base paper and subsequently pressed with a heated mirror surface drum to finish a strong luster surface while the coated layer is kept in a wet state, a base paper obtained by processing a slurry containing pulp and a filler into paper and drying the paper is employed as the above- mentioned base paper, the slurry being mixed with a cationic polymer and an anionic polymer and/or anionic inorganic particles so as to give a value >=that represented by an equation: Y=90.logX-130 (Y is the yield (wt.%) of the filler and fine paper fibers; x is the weight (g/cm<2>) of the base paper) to the yield of the filler and fine paper fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing cast coated paper, and in particular to a method for producing high quality cast coated paper with high productivity. .

(Prior art) Cast coated paper is made by coating a base paper with a water-soluble coating liquid containing pigments and adhesives as main components, and then applying a heated drum to finish the coating layer, which has plasticity in a wet state, to a mirror finish. The cast coated paper obtained in this way has a higher white gloss and excellent surface smoothness than normal coated paper with a super calendar finish. Because of this, extremely excellent printing effects can be obtained, and it is used for high-grade printed materials and high-grade paper containers.

However, since the wet coating layer is dried by pressing it directly onto the heating drum, the moisture in the coating layer must pass through the base paper layer and evaporate to the opposite side. Compared to conventional coated paper, which is dried from the top of the coating, it is produced at a much slower rate and has lower productivity.

Conventionally, various efforts have been made to increase the moisture permeability of the base paper layer and increase the productivity of cast coated paper.

For example, in Japanese Unexamined Patent Publication No. 56-26094, an attempt has been made to increase air permeability by subjecting cast-coated Kawahara paper to corona discharge or spark discharge treatment in advance to form micropores on the entire surface.

However, although this method apparently lowers the air permeability, it does not improve the air permeability of the base paper layer during the production of cast coated paper, making it difficult to significantly increase the productivity of cast coated paper.

On the other hand, in order to improve the productivity of cast coated paper, improvements have been made to manufacturing equipment, manufacturing methods, coating liquid compositions, and the like.

For example, a method is used in which an undercoat layer containing pigment and adhesive as main components is first provided on a base paper, and after drying or semi-drying, a wet coating layer is provided as an overcoat layer.

According to this method, the quality of cast coated paper can be sufficiently maintained even if the coating amount of the wet coating layer is reduced. The absolute amount of moisture can be reduced, and the amount of water vapor passing through the base paper layer to the other side can be reduced.

However, the air permeability of the base paper with the undercoat layer is
Because of the effect of the undercoat layer, the water vapor becomes difficult to escape, so we created an undercoat layer to reduce the amount of wet coating layer, and although the amount of evaporated water was reduced, cast coated paper The drying properties are not promoted and the productivity is not improved much.

(Problems to be Solved by the Invention) As stated above, in conventional cast coated paper, by increasing the air permeability of the base paper and increasing the drying speed, the operating speed during production of cast coated paper can be increased and production can be improved. Increasing the properties of cast-coated paper has become an important issue in the production of cast-coated paper.

In order to increase the productivity of cast coated paper, the present inventors
As a result of intensive studies to improve the air permeability of base paper, we found that cationic polymers, anionic polymers, and / Or add anionic inorganic particles to increase the retention rate of filler and fine fibers (Y
) is greater than or equal to the value expressed by the following formula. By using a base paper obtained by papermaking and drying, Y = 90-10g It is the yield rate of fibers or the basis weight of the base paper in g/cm2.

That is, it has been found that air permeability can be increased without deteriorating the texture of base paper by manufacturing it using a papermaking method generally called a high-yield system.

That is, in -m, the factory that manufactures base paper in the paper machine is
Bulb fibers, fine fibers, fillers, sizing agents, etc. etc.) are mainly used), and in the bottom water process, a sheet is formed by the entanglement of the valve fibers, and then a base paper is manufactured through a pressing and drying process.

The base paper obtained in this way has fine fibers and filler removed from the part that came into contact with the wire during the papermaking process, and there are slight gaps, but the rest of the paper has a network structure made of pulp fibers. It has a structure in which fillers and fine fibers are piled up, blocking the mesh.

For this reason, it was found that the distribution of minute voids was different and the water vapor permeability was inferior compared to base paper using a high-yield system.

In other words, in the case of base paper made using a high-yield system, pulp fibers, fine fibers, and filler form micro flocs, and then a sheet is formed, so the mesh created by the entanglement of pulp fibers consists of fine fibers, It easily remains without being blocked by filler.

When producing cast coated paper using such base paper,
Compared to the case of using base paper produced by conventional methods, water vapor permeability is significantly improved, drying speed is increased, and cast coated paper can be produced with high productivity.

(Means for Solving the Problems) The present invention provides a coating layer mainly composed of pigment and adhesive on a base paper, and the coating layer is applied to a heated mirror drum while in a wet state. In a method for producing cast-coated paper that is pressed and has a strong gloss finish, a cationic polymer, an anionic polymer, and/or anionic inorganic particles are added to a slurry containing pulp and filler as the base paper. Y is added, and the base paper obtained by papermaking and drying is used so that the yield rate (Y) of filler and fine fibers in the papermaking process is equal to or higher than the value expressed by the following formula. -90・logX
-130 Here, Y is the yield rate of filler and fine fibers expressed in weight %, and X is the basis weight of the base paper expressed in 27 cm2.

This is a method for producing cast coated paper.

Examples of the cationic polymer according to the present invention include acrylamide polymers having a cationic group and cationically modified starch, and examples of the anionic polymer include an acrylamide polymer having an anionic group.

That is, the base paper used in the present invention contains one type of cationic polymer selected from acrylamide polymers having cationic groups, cationically modified starch, etc., and anionic groups in a slurry containing pulp and filler. an acrylamide-based polymer and/or anionic inorganic particles having This is the base paper obtained by

Y=901 og

The fine fibers and fillers in the pulp slurry form micro flocs in the papermaking process through the action of cationic polymers, anionic polymers, and/or anionic inorganic particles, and then sheets are formed. The network created by the entanglement is fine fibers, which tend to remain unblocked by filler.

As a result, a base paper with high air permeability through which water vapor can easily pass is obtained.

The acrylamide polymer having a cationic group used in the present invention may be a Huffmann decomposition product of an acrylamide polymer, a Mannich reaction product, or a variety of acrylamide polymers containing (meth)acrylamide and a tertiary amine group or a quaternary ammonium group. Examples include copolymers with (meth)acrylate monomers and/or (meth)acrylamide monomers.

As the cationically modified starch, any starch containing a tertiary amino group or a quaternary ammonium group can be used, but especially the degree of substitution (D, S/glucose unit)
is preferably 0.02 or more.

The anionic polyacrylamide preferably contains 1 to 20 mol% of anionic groups in the molecule, and these can be obtained by partially hydrolyzing polyacrylamide.

The amount of the acrylamide polymer having a cationic group or cationically modified starch added is 0.005 to 0.1 part by weight per pulp in the case of an acrylamide polymer having a cationic group, and in the case of a cationically modified starch. 0.1 to 2.0 parts by weight is common.

In addition, the amount of anionic polyacrylamide and anionic inorganic particles added is 0.005 to 0.05 parts by weight per pulp in the case of anionic polyacrylamide.
In the case of anionic inorganic particles, 0.02~ per pulp
0.5 parts by weight is common.

If the ratio is less than the minimum ratio specified above, the desired effect cannot be obtained, and if the ratio exceeds the upper limit, the texture tends to deteriorate.

As for the method of adding cationic polymers, anionic polymers, and/or anionic inorganic particles, if you avoid adding the cationic polymers, anionic polymers, and/or anionic inorganic particles at the same time, However, for boat fishing, it is preferable to add the cationic type and the anionic type in that order, and add the latter after allowing time for the former to be sufficiently dispersed in the pulp.

The pulp used in making base paper in the high-yield system of the present invention is those used in ordinary paper machines, such as chemical pulp (KP, SP, AP, etc.), mechanical pulp (SGP, SCP.

RGP, CGP, TMP, CTMP, etc.), waste paper pulp (
DIR, etc.). These pulps are blended appropriately according to the specifications of the final product, and after undergoing mechanical treatment,
Necessary auxiliaries are added and the paper is run through a paper machine. Mochi theory,
The paper machine used in this case is not limited to a Fourdrinier type or cylinder type paper machine, but may also be a double-sided dewatering type paper machine that has been widely used in recent years.

Further, the paper making method is not particularly limited, and may be any method such as acid paper making or neutral (alkaline) paper making. Furthermore, when making these base papers, like general base papers, for example, in the case of acid paper making, talc, kaolin, plastic pigments,
In the case of neutral (alkaline) papermaking, fillers such as urea resin, calcium carbonates such as heavy calcium carbonate and light calcium carbonate, talc, kaolin, plastic pigments, and urea resin are included in the pulp slurry. It is mixed appropriately. The basis weight of the cast-coated Kawahara paper made under the above conditions is adjusted within a range of about 30-300 y/s.

In the method of the present invention, cast coated paper is manufactured using the specific base paper prepared as described above, but the coating liquid composition for cast coating is not particularly limited, and generally A coating liquid composition for cast paper containing the pigment and adhesive used as main components can be used.

Examples of pigments include clay, kaolin, aluminum hydroxide, calcium carbonate, titanium oxide, barium sulfate,
zinc oxide, sachin white, plastic pigment,
Pigments commonly used for coated paper, such as urea resin, can be used alone or in combination.

Adhesives include starch, modified starch, casein,
Normal water-based coating compositions such as natural adhesives such as protein, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, acrylic ester emulsion latex, synthetic polymer adhesives such as polyvinyl alcohol, etc. One or more of various natural and synthetic adhesives used in products may be used in appropriate combinations.

Furthermore, various auxiliary agents such as dispersants, release agents, waterproofing agents, antifoaming agents, dyes, coloring pigments, preservatives, etc. can be suitably added to the coating composition as required.

Note that the specific base paper used in the present invention can be coated with a general pigment coating composition on one or both sides, if necessary.

The coating amount is preferably about 5 to 30 g/n2.

As a method for producing cast coated paper using the specific base paper of the present invention, any of the known cast coating methods, wet cast method, rewet cast method, and tartar cast method may be used. However, the effects of the present invention are particularly noticeable in wet casting methods and gelling casting methods.

(Effects of the invention) By using the specific base paper of the present invention, the water vapor permeability is significantly improved compared to the case of using base paper manufactured by a conventional method, and as described in the examples, the water vapor permeability is significantly improved. It became possible to produce cast coated paper.

(Examples) Next, in order to explain the present invention more specifically, examples will be given and explained, but the present invention is not subject to equivalent restrictions by these examples.

Note that all parts in the examples are by weight unless otherwise specified.

Further, in the examples, the white paper gloss and surface properties are values determined as follows.

White Paper Gloss: 75° gloss was measured using a Murakami Color Technology Research Break Gloss meter.

Surface properties: The surface properties of cast coated paper are determined by visual inspection of uneven gloss on the surface due to the texture of the base paper.Excellent), ○, △, × (poor)
It was evaluated on a four-level scale.

Example I A valve slurry consisting of 90 parts of NBKPIO and 90 parts of LBKP was mixed with 0.1 part of alkyl ketene dimer, cationic polyacrylamide (trade name KL-65, manufactured by Wakidachi Organic Industrial Research Institute), and anionic polyacrylamide (trade name Barmite). B-15. Prepare a paper stock to which 10 parts of light calcium carbonate (manufactured by Harima Kasei Kogyo Co., Ltd.) and light calcium carbonate are added as a filler, make paper using a paper machine, and add 1.5 g of oxidized starch on both sides.
Size press processing is performed to adhere 7m2, and the basis weight is 8.
A cast coated Kawahara paper weighing 5 g/m2 was obtained. This base paper was coated with the following composition: kaolin casein styrene-butaratex 100 parts exfoliating antifoaming agent 10 parts diene copolymer 15 parts 5 parts 0.5 parts coating liquid composition with a solid content concentration of 45%. The material was coated so that the coating amount was 2"ig/vs2 in terms of dry weight, and immediately brought into close contact with a chrome-plated cast drum with a diameter of 600 nm heated to 85°C and dried. Get the paper.

The quality of the cast coated paper obtained in this way was completely satisfactory, and the operating speed could be increased without causing any operational problems such as drum blistering or drum blistering caused by insufficient drying.

The results obtained are shown in Table 1.

Comparative Example 1 Cast coated paper was obtained in the same manner as in Example 1 except that instead of using cationic polyacrylamide and anionic polyacrylamide together, cationic polyacrylamide was used alone to make the paper. .

Table 1 shows the operability results and paper quality during casting.

Example 2 A valve slurry consisting of 100 parts of LBKP as in Example 1 was added with 0.1 part of alkyl ketene dimer, cationic modified starch (trade name: CATO-F, manufactured by Oji National Co., Ltd.), and anionic polyacrylamide (trade name: Barmite B15). . manufactured by Yokoma Kasei Kogyo Co., Ltd.) and 10 parts of light calcium carbonate as a filler was prepared, and paper was made using a paper machine, and 1.5 fI/m2 of oxidized starch was added on both sides.
Size press treatment is performed to ensure adhesion, and the basis weight is 100 FI.
/+s2 cast coated paper base paper was obtained.

The following distribution was applied to this base paper: 80 parts kaolin, 20 parts casein.
10 parts styrene-butadiene copolymer 15 parts latex peeling 5 parts antifoaming agent
A coating liquid composition composed of 0.5 parts and having a solid content concentration of 45% was coated in the same manner as in Example 1 to obtain a cast coated paper.

Table 1 shows the operability results and paper quality results during cast coating.

Comparative PA2 A cast coated paper was obtained in the same manner as in Example 2 except that instead of using a combination of cationically modified starch and anionic polyacrylamide, cationically modified starch was used alone to make the paper.

Table 1 shows the operability results and paper quality during casting.

Example 3 Bulb slurry consisting of 100 parts of LBKP similar to Example 2, 0.1 part of alkyl ketene dimer, cationic polyacrylamide (trade name KL65, manufactured by Wakidachi Organic Industrial Research Institute), natural zeolite (Itaya district, Yamagata prefecture) A paper stock was prepared by adding 10 parts of light calcium carbonate as a filler, and made into paper using a paper machine. /II2 Perform size press treatment to ensure adhesion to obtain cast coated paper Kawahara paper with a basis weight of 100 g/m''.

The obtained base paper was coated with the same coating liquid composition as in Example 2 in the same manner as in Example 1 to obtain a cast coated paper.

Table 1 shows the operability results and paper quality results during cast coating.

Example 4 A pulp slurry consisting of 15 parts of NBKP and 85 parts of LBKP as in Example 1 was mixed with 0.5 parts of rosin size, 2.0 parts of sulfuric acid, and cationic polyacrylamide (trade name: KL-65. (manufactured by Kyoritsu Organic Industrial Research Institute), anionic polyacrylamide (trade name: Barmite 13-15.ill, manufactured by Kasei Kogyo Co., Ltd.), and 10 parts of talc for papermaking as a filler were prepared, and paper was made using a paper machine. , 1.5y/+ oxidized starch on both sides
Size press processing is performed so that it fits 21 inches, and the basis weight is 8
A base paper for cast coated paper having a weight of 59/l112 was obtained.

This base paper was coated with the same coating composition as in Example 1 in the same manner as in Example 1 to obtain a cast coating.

Table 1 shows the operability results and paper quality results during cast coating.

Comparative Example 3 Cast coated paper was obtained in the same manner as in Example 4, except that instead of using cationic polyacrylamide and anionic polyacrylamide in combination, cationic polyacrylamide was used alone to make the paper. .

Table 1 shows the operability results and paper quality during casting.

Example 5 Everything was the same as Example 1 except that the types and amounts of the cationic and anionic polymers in Example 1 were blended as shown in Table 1.
I obtained the cast coated paper in the same way. Table 1 shows the cast operability results and paper quality.

Example 6 A pulp slurry consisting of 100 parts of the same LBKP as in Example 2 was added with 0.5 parts of rosin size, 2.0 parts of sulfate band, cationic modified starch (trade name: CATO-F, manufactured by Oji National Co., Ltd.), and anionic polyester. A paper stock to which acrylamide (trade name Burmite B15, manufactured by Yokoma Kasei Kogyo Co., Ltd.) and 10 parts of talc for paper making as a filler was added was prepared, and paper was made using a paper machine, and 1.5 g/n2 of oxidized starch was added on both sides.
Size press treatment is applied to make it adhere, and the basis weight is 100y.
/m2 cast coated paper Kawahara paper was obtained.

A coating composition similar to that in IM2 was applied to this base paper in IM2.
A cast coated paper was obtained by coating in the same manner as A2.

Table 1 shows the operability results and paper quality during casting.

Example 7 Everything was the same as Example 2 except that the types and amounts of the cationic and anionic polymers in Example 2 were blended as shown in Table 1.
I obtained the cast coated paper in the same way. Table 1 shows the cast operability results and paper quality.

Comparative Example 4 A cast coated paper was obtained in the same manner as in Example 6 except that instead of using a combination of cationic modified starch and anionic polyacrylamide, cationic modified starch was used alone to make paper.

Table 1 shows the operability results and paper quality during casting.

Example 8 A base paper for cast coated paper having a basis weight of 66 g/n2 was obtained in the same manner as in Example 1, except that the paper was made using a paper machine having a double-sided dewatering mechanism.

This base paper was subjected to casting processing in exactly the same manner as in Example 1 to obtain cast coated paper.

Table 1 shows the operability results and paper quality during casting.

Example 9 Cast-coated Kawahara paper with a basis weight of 85 fI/m2 was obtained in the same manner as in Example 4, except for the pulp composition consisting of 10 parts of NBKP, 80 parts of LBKP, and 10 parts of mechanical pulp (CTMP).

This base paper was cast in exactly the same manner as in Example 4 to obtain a cast coated paper.

Table 1 shows the operability results and paper quality during casting.

Example 10 Cast coated paper was obtained in the same manner as in Example 5 except for the pulp composition consisting of 80 parts of LBKP and 20 parts of DIR.

Table 1 shows the operability results and paper quality during casting.

Comparative Example 5 Paper was made using a paper machine having a double-sided dewatering mechanism in the same manner as in Example 8, but instead of using cationic polyacrylamide and anionic polyacrylamide in combination, cationic polyacrylamide was used alone, and the basis weight was 66y. /Tt
12 base papers for cast coated paper were obtained.

This base paper was subjected to casting processing in exactly the same manner as in Example 1 to obtain cast coated paper.

Table 1 shows the operability results and paper quality during casting.

hand Continued Supplementary Positive book

Claims (1)

[Claims] 1. A coating layer mainly composed of pigment and adhesive is provided on base paper, and while the coating layer is in a wet state, it is pressed against a heated mirror drum to give a strong gloss finish. In a method for producing cast coated paper, a cationic polymer, an anionic polymer and/or anionic inorganic particles are added to a slurry containing pulp and filler as the base paper, and A method for producing cast coated paper, characterized by using base paper obtained by papermaking and drying so that the yield rate (Y) of filler and fine fibers is equal to or higher than the value expressed by the following formula. . Y = 90.log