JPH08296197A - Coated paper for printing - Google Patents

Abstract

PURPOSE: To obtain a coated paper for printing having excellent folding crack resistance and printability by applying an undercoating layer composed mainly of a pigment and a copolymerized latex adhesive and a top-coating layer to a base paper containing a cationic surfactant. CONSTITUTION: A base paper containing a cationic surfactant such as a quaternary ammonium salt having at least one >=16C alkyl group such as dioleyl dimethyl ammonium chloride is produced by adding 0.05-1.5wt.% (based on the solid content of the pulp) of the cationic surfactant to a pulp slurry and making a paper from the slurry or applying the surfactant to the surface of a formed paper as a sizing agent. The base paper is coated with an undercoating agent produced by mixing 100 pts.wt. of a pigment such as kaolin or soft calcium carbonate with >=15 pts.wt. (preferably 20-30 pts.wt.) of an adhesive composed of a copolymer latex such as styrene-butadiene copolymer and the coated paper is dried, coated with a top-coating agent consisting of a pigment and an adhesive almost same as those of the undercoating agent, dried and subjected to supercalender finishing to obtain the objective cast-coated paper for printing.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coated paper for printing,
In particular, the present invention relates to a coated paper for printing which has folding crack resistance and excellent printability.

[0002]

2. Description of the Related Art In recent years, as the use of coated paper for printing, it is often used for the covers of magazines, pamphlets and the like and cover covers of various books with the trend toward visualization, colorization and high quality of printed materials. Is coming. Further, it may be used for a fashionable paper bag such as a shopping bag. In any case, in the bookbinding process, the bag manufacturing process, or the like, the printed coated paper for printing is subjected to processing such as folds. At this time, the coating layer at the crease portion is likely to crack, and if it gets worse, the printed part is torn and the base paper layer is exposed, so-called fold cracking phenomenon is often seen, impairing the appearance as a product and reducing the commercial value. Will lower it.

As a method of preventing cracks and tears of the coated paper (coating layer) for printing against the above-mentioned creases, that is, a method of imparting so-called crease resistance, it is necessary to apply the method to the surface of ordinary coated paper or cast coated paper. A so-called laminated product in which a plastic film such as polyethylene, polypropylene, or vinyl chloride is laminated is widely used. In general, the above-mentioned laminated paper cannot be printed from above with ordinary printing ink, so that printing is performed in advance and then laminating is performed. In addition, although this laminated paper has dramatically improved suitability for folding, it is difficult to recycle and disintegrate it as waste paper, and the process becomes more complicated and costly, making it more environmentally friendly than ordinary coated paper. There are many disadvantages. From such an actual situation, in place of laminated paper, development of coated paper for printing having the same quality as those, that is, it has better folding resistance than existing coated paper, and is excellent. It is desired to develop a coated paper for printing which has excellent printability.

Conventionally, as a coating composition which constitutes a coating layer of a coated paper for printing, a pigment and an adhesive, which are generally used in the field of producing coated paper for printing, are used as a main component, and an adhesive is used. For example, a natural binder such as casein and soybean protein is used in combination with a synthetic binder such as SBR latex, and the amount thereof is usually 5 to 15 parts by weight based on 100 parts by weight of the pigment. However, in actuality, from the aspect of printability such as ink absorbability, it is the actual condition that the amount is 5 to 10 parts by weight. As described above, since the main component of the coating layer is the pigment, it has excellent printability but poor elasticity. Therefore, when the printing coated paper provided with the pigment coated layer is folded, the pigment coated layer cannot withstand the tensile force and the compressive stress generated at that time, and the coated layer is cracked, thus covering the synthetic film and the like. It is incomparable to laminated paper.

Therefore, in order to improve the folding crack resistance of the coated paper for printing, it is necessary for the coated layer to have elasticity so as not to be broken by tensile stress or compressive stress. By the way, as to the cast coated paper, as the adhesive in the coating composition constituting the coating layer, natural adhesives such as casein, starch and soybean protein, and synthetic adhesives such as copolymer latex are used. Agents are used in combination.
Normally, natural adhesives are harder and more brittle than synthetic adhesives, so it is possible to mix synthetic adhesives (copolymer latex, etc.) at a high rate in order to improve the elasticity of the coating layer. To be However, the high proportion of synthetic adhesives
It causes a decrease in ink drying property during printing and also has a bad influence on quality.

On the other hand, the base paper also has elasticity due to fiber-to-fiber bonding, but this elasticity is different from that of the coating layer, and this difference in elasticity hinders the dispersion of stress and causes folding cracks. May be. As described above, it is difficult at present to manufacture a coated paper for printing which has both breakability and ink drying property.

[0007]

In light of the above-mentioned circumstances, the present inventors have found that the coated paper for printing has the same resistance to breakage as that of laminated paper, has high gloss, and is excellent in printability. Earnestly researched repeatedly. As a result, the present invention contains a cationic surfactant in the base paper, and on this base paper, an undercoat coating layer containing a copolymer latex as an adhesive of the coating composition with respect to the pigment in a specific ratio is provided. Provided,
By providing an overcoat coating layer thereon, it is possible to provide a coated paper for printing which has the extremely excellent folding crack resistance and the excellent printability which are desired by the present invention.

[0008]

DISCLOSURE OF THE INVENTION The present invention is a coated paper for printing comprising a base paper and an undercoating layer and a topcoating layer containing a pigment and an adhesive as main components. A pigment 10 containing a cationic surfactant and containing a copolymer latex as an adhesive in the undercoat layer is used.
The coated paper for printing is characterized by containing 15 parts by weight or more with respect to 0 parts by weight.

[0009]

As described above, the inventors of the present invention have prepared a base coat composition obtained by incorporating a cationic surfactant in the base paper and mixing the base paper with a copolymer latex as an adhesive in a specific ratio or more. By providing an undercoating coating layer by coating and then providing an overcoating coating composition containing a pigment and an adhesive as a main component on the coating layer, excellent crease resistance and printability are provided. It was found that the above excellent coated paper can be obtained, and the present invention has been completed.

That is, in the present invention, by incorporating a cationic surfactant in the base paper, the interfiber bond in the base paper is relaxed and the flexibility of the base paper is improved. Furthermore, by blending 15 parts by weight or more of the copolymer latex in the undercoat coating composition, the flexibility of the coating layer is improved, and the synergistic effect of both improves the suitability for folding and cracking. However, if 15 parts by weight or more of the copolymer latex is blended in the undercoat layer with respect to 100 parts by weight of the pigment, the ink drying property of the underlayer is deteriorated and printability and paper quality are deteriorated.

Therefore, in the present invention, the flexibility of the composition of the overcoat layer is reduced (the amount of adhesive is reduced as much as possible, an appropriate amount of pigment excellent in ink absorbability is used, or an auxiliary agent for improving ink absorbability is added. And the like) to compensate for the above-mentioned negative points and to provide a coated paper for printing which is excellent in folding crack resistance and printability. Accordingly, the present invention requires at least two layers, a base coat and a top coat layer. Incidentally, the compounding ratio of the copolymer latex in the overcoat layer is 5 to 100 parts by weight of the pigment.
It is adjusted to about 10 parts by weight.

As described above, in the present invention, a cationic surfactant is contained in the base paper, and at least 15 parts by weight of the copolymer latex is added to the undercoating composition as an adhesive per 100 parts by weight of the pigment. The feature is that the coated composition is applied onto the base paper.

Examples of the cationic surfactant to be contained in the base paper include alkyltrimethylammonium salt, dialkyldimethylammonium salt, alkyldimethylbenzylammonium salt, acylaminoethyldiethylammonium salt, acylaminoethyldiethylamine salt and alkyl. Amidopropyldimethylbenzyl ammonium salt, alkylpyridinium salt, alkylpyridinium sulfate, stearamidomethylpyridinium salt,
Alkylquinolinium salts, alkylisoquinolinium salts, fatty acid polyethylene polyamides, quaternary ammonium salts such as acylaminoethylpyridinium salts, acylcholaminoformylmethylpyridinium salts, stearooxymethylpyridinium salts, fatty acid triethanolamine, Fatty acid triethanolamine formate salt, trioxyethylene fatty acid triethanolamine, cetyloxymethylpyridinium salt, p-isooctylphenoxyethoxyethyldimethyldimethylbenzylammonium salt and other ester-bonded amines and ether-bonded quaternary ammonium salts, alkylimidazolines, 1 -Hydroxyethyl-2-alkylimidazoline, 1-acetylaminoethyl-2-alkylimidazoline, 2-alkyl-4-methyl-4-
Heterocyclic amines such as hydroxymethyloxazoline, polyoxyethylene alkylamines, N-alkyl propylene diamines, N-alkyl polyethylene polyamines,
N-alkyl polyethylene polyamine dimethyl sulfate,
Examples thereof include amine derivatives such as alkyl biguanides and long-chain amine oxides.

Of these, quaternary ammonium salts having an alkyl group having 16 or more carbon atoms, preferably having 16 or more and 30 or less carbon atoms are used.
Then, one or two or more of them are mixed and used in the pulp. The amount of addition in this case is from 0.05 to 1.5% by weight based on the solid content in the pulp slurry for papermaking, or as a surface sizing liquid by a size press or the like. It is also possible to apply it from the surface and attach it.

Incidentally, the adhesion amount is 0.05 per pulp.
When the content is less than wt%, it is difficult to obtain sufficient flexibility, and it is difficult to obtain satisfactory folding crack resistance. On the other hand, 1.5
If it exceeds the weight%, the paper strength, especially the interlaminar strength may be deteriorated. When the surfactant is an anionic surfactant, a nonionic surfactant, or an amphoteric surfactant, a sufficient softening effect cannot be obtained, and a desired folding cracking resistance cannot be obtained.

The base paper used in the present invention is not particularly limited as long as the base paper containing the above-mentioned cationic surfactant is used, and the acid paper used for general coated paper is not limited. Alternatively, neutral paper is applied as appropriate. The printing coated paper according to the present invention can be applied to ordinary printing coated paper, for example, cast coated paper, art paper, general coated paper, medium coated paper, and the like. When applied to a cast coated paper which is a coated paper for printing, a desired effect can be remarkably obtained.

As described above, in the present invention, if the top coating layer is not provided, the ink drying property is poor and the coated paper is inferior in printability, and the product value is reduced.

Next, examples of pigments constituting the undercoat layer include kaolin, clay, calcined clay, amorphous silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, satin white, aluminum silicate, magnesium silicate. , Magnesium carbonate, diatomaceous earth, styrene-based plastic pigments, urea resin-based plastic pigments, benzoguanamine-based plastic pigments, and the like, various pigments used in the general coated paper manufacturing field can be used alone or in combination of two or more kinds.

The adhesive, which is one of the coating layer components, contains a copolymer latex as an essential component, and its blending amount is 15 parts with respect to 100 parts by weight of the pigment.
It is used in an amount of not less than 20 parts by weight, preferably 20 to 30 parts by weight. By the way, if the blending amount exceeds 30 parts by weight, the ink drying property is significantly deteriorated, and at the same time, various problems are caused in terms of paper quality and productivity, for example, in the case of general coated paper, there is a problem such as deterioration of gloss. Because there is a concern that it is easy to cause,
It is desirable to adjust the amount to 15 parts by weight or more and 30 parts by weight or less.

In addition to the above-mentioned copolymer latex, known publicly-known adhesives used in the field of production of general coated paper, for example, proteins such as casein and soybean protein, positive starch, and oxidized starch, if necessary. , Starches such as esterified starch, styrene-butadiene copolymer, conjugated methacrylate copolymer latex such as methyl methacrylate-butadiene copolymer latex,
An acrylic polymer latex such as a polymer or copolymer of acrylic acid ester and methacrylic acid ester, a vinyl polymer latex such as ethylene-vinyl acetate copolymer, or a carboxyl group of these various polymers or copolymers. Alkali-soluble or alkali-insoluble (co) functionalized with functional group-modified monomers such as
A synthetic resin adhesive such as polymer latex, polyvinyl alcohol, olefin-maleic anhydride resin and melamine resin, and cellulose derivative such as carboxymethyl cellulose and hydroxyethyl cellulose are appropriately used.

Further, in the coating composition (hereinafter, simply referred to as paint) constituting the undercoat coating layer, in addition to the above-mentioned pigment and adhesive, a defoaming agent, a dispersant, a defoaming agent, Various auxiliary agents such as a release agent, a flow modifier, a water resistance agent, a preservative, an antistatic agent, a colorant, and a fluorescent dye can be appropriately used as necessary.

The undercoating layer coating material composed of the above-mentioned materials generally has a solid content of 20 to 70% by weight.
Was adjusted to an extent, dry weight basis weight of about 20 to 400 g / m ² approximately on the base paper 5 to 25 g / m ^2, more preferably 1
Blade coater, so that it is about 0 to 15 g / m ² .
After coating with various publicly known coating devices such as an air knife coater, a roll coater, a brush coater, a chanplex coater, a bar coater, and a gravure coater,
To be dried.

After the base coating composition is coated on the base paper and dried as described above, the coating layer is further coated on the base coating layer.
Finishing the product is performed by applying a coating material for a top coating layer containing a pigment and an adhesive as main components and drying. As the pigment and adhesive in this case, the same pigment and adhesive as those used in the undercoat coating layer are used. However, regarding the pigment and adhesive in this case, since the undercoat coating layer has a composition in which the ink drying property is considerably lowered, the compounding balance that improves the ink drying property in the compounding amount and selection is Must be considered.

From the above, the compounding ratio of the copolymer latex in the overcoat layer is not particularly limited, but is usually adjusted to about 5 to 10 parts by weight with respect to 100 parts by weight of the pigment. Furthermore, if necessary, ordinary natural adhesives such as casein and starch can be appropriately used in combination. In addition, the coating material for the overcoat layer is a blade coater, an air knife coater, a roll coater, so that the dry weight is about 5 to 25 g / m ² , more preferably about 10 to 15 g / m ² .
It is coated and dried using various known coating devices such as a brush coater, a chanplex coater, a bar coater and a gravure coater.

The above description is based mainly on general coated paper, but of course, it is also applicable to cast coated paper, and in the case of the present invention, it is rather cast coated paper. A superior effect can be obtained when applied. As a method for finishing the cast coated paper, press contact with the surface of the heating drum, which is a mirror finish of the coating layer in a conventionally known wet state,
Wet cast method of drying, releasing and gloss finish,
After the wet coating layer is once dried, it is plasticized with a re-wetting liquid, and then a rewet casting method is performed in which the heated mirror surface of the drum is pressed and released, and the wet coating layer is gelled. After that, a gelling casting method or the like in which the heating mirror surface drum surface is pressed and finished can be appropriately adopted.

[0026]

The present invention will be specifically described below with reference to examples, but of course the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Example 1 Kaolin (trade name: UW-90 / Engelhard USA) 70 parts, light calcium carbonate (trade name: Brilliant S-15 / Shiraishi Industry Co., Ltd.) 30 parts, oxidized starch 2
And 25 parts of styrene-butadiene copolymer latex (each based on solid content) were mixed to give a solid content of 6
A 0% undercoat paint was prepared.

On the other hand, as a cationic surfactant, dioleyldimethylammonium chloride (trade name: cation 2-OL) having two alkyl groups having 18 carbon atoms.
R / made by Nippon Oil & Fats Co., Ltd. is added to the pulp slurry so that the ratio to the pulp is 1.0%, and the paper stock prepared is added to produce 10 tsubo.
A high quality base paper of 5 g / m ² was obtained. Using a blade coater, one side of this base paper was coated with the undercoat layer coating material so that the dry weight was 15 g / m ^2, and dried to obtain an undercoat base paper.

Then, 80 parts of kaolin and light calcium carbonate, which are the same as those used in the above-mentioned coating material for the undercoat layer, are added.
0 part, further 10 parts of oxidized starch, 10 parts of styrene-butadiene copolymer latex, solid content concentration is 58%
Was prepared on the surface of the undercoat base paper coated with a bar coater to give a dry weight of 10 g /
After coating and drying to obtain m ² , the linear pressure is 300 kg / cm.
Super calendering was done at to obtain coated paper for printing.

Example 2 In Example 1, octadecyltrimethylammonium chloride (trade name: cation AB /, which has one alkyl group having 18 carbon atoms, is used in place of dioleyldimethylammonium chloride as the cationic surfactant.
A coated paper for printing was obtained in the same manner as in Example 1 except that Nippon Oil & Fats) was used.

Example 3 A coated paper for printing was prepared in the same manner as in Example 1 except that the styrene-butadiene copolymer latex blended in the undercoat layer coating composition was changed from 25 parts to 32 parts. Obtained.

Example 4 A coated paper for printing was prepared in the same manner as in Example 1 except that the styrene-butadiene copolymer latex compounded in the undercoat layer coating composition was changed from 25 parts to 18 parts. Obtained.

Example 5 In Example 1, dodecyltrimethylammonium chloride (trade name: cation BB / Japan, which has one alkyl group having 12 carbon atoms in place of dioleyldimethylammonium chloride as a cationic surfactant) A coated paper for printing was obtained in the same manner as in Example 1 except that oil and fat was used.

Example 6 80 parts of the same kaolin as in Example 1, 20 parts of light calcium carbonate, 10 parts of a 15% aqueous casein solution dissolved in ammonia (on a solids basis), 15 parts of a styrene-butadiene copolymer latex, A coating solution for casting having a concentration of 45% was prepared by adding 1 part of ammonium stearate as a release agent, and this coating composition was coated on the same base coat as in Example 1 to give a dry weight of 10 g / m ² . While the coated coating material was in a wet state, it was pressed against the surface of a heating cast drum having a surface temperature of 80 ° C. and released to give a strong gloss finish to obtain a cast coated paper.

Comparative Example 1 A coated paper for printing was obtained in the same manner as in Example 1 except that 25 parts of the styrene-butadiene copolymer latex in the undercoat layer coating composition was changed to 10 parts. .

Comparative Example 2 A coated paper for printing was obtained in the same manner as in Example 1 except that 25 parts of the styrene-butadiene copolymer latex in the undercoat layer coating composition was changed to 13 parts. .

Comparative Example 3 In Example 1, the cationic surfactant internally added to the base paper was used as anionic surfactant, sodium normaldodecylbenzenesulfonate (trade name: Nurex R).
A coated paper for printing was obtained in the same manner as in Example 1 except that the coating paper was changed to (/ NOF Corporation).

Comparative Example 4 In Example 1, the cationic surfactant internally added to the base paper was polyoxyethylene nonyl phenyl ether (trade name: Nonion NS-210, which is a nonionic surfactant).
A coated paper for printing was obtained in the same manner as in Example 1 except that the coating paper was changed to (/ NOF Corporation).

Comparative Example 5 A coated paper for printing was obtained in the same manner as in Example 1 except that the cationic surfactant dioleyldimethylammonium chloride was not added to the base paper.

Comparative Example 6 In Example 1, the coating amount of the undercoat layer coating material was applied and dried so that the dry weight was 25 g / m ^2, and the supercoat was applied as it was without an upper coating layer. Calendar finishing was performed to obtain a coated paper for printing.

Comparative Example 7 Example 1 was repeated except that the cationic surfactant was not added to the base paper and 25 parts of the styrene-butadiene copolymer latex in the coating material for the undercoat layer was changed to 10 parts. A coated paper for printing was obtained in the same manner as in.

Comparative Example 8 A wet cast coated paper was obtained in the same manner as in Example 6 except that the cationic surfactant was not added to the base paper.

Comparative Example 9 A cast coated paper was obtained in the same manner as in Example 6 except that 25 parts of the styrene-butadiene copolymer latex in the undercoat layer coating composition was changed to 10 parts.

For each printing coated paper obtained as described above, the type of surfactant, the number of parts of the copolymer latex blended in the undercoat and topcoat coating layers with respect to 100 parts of the pigment, and the finishing method ( Normal coated paper finish =
Super calender, cast finish = wet cast) are shown in Table 1, and further evaluation of folding cracking suitability and ink setting property is performed by the methods shown below, and the obtained results are shown in Table 2.

(Folding cracking suitability) Ink for sheet offset (RI manufactured by Dainippon Ink and Chemicals, Inc.
Ans-G ink) 0.3 cc is used to print the surface of the cast coated paper once, and one day later, the printed surface is folded outward (hereinafter referred to as a mountain fold), and a metal roll weighing 10 kg is placed thereon. The product was rolled back and forth once in a direction perpendicular to the fold line, and the state of the fold line was visually observed and judged according to the following criteria. The same operation was also performed for the case where the printing surface was folded inward (hereinafter referred to as valley fold). ⊚: No cracks or splits are found in the folds. ◯: Some cracks are seen at the folds, but there is no exposed portion of the base paper layer due to tearing of the printed part. Δ: There is a part where the base paper layer is exposed because the printed part is torn at the fold. X: The printed part is torn over the entire fold and the base paper layer is exposed.

(Ink setting property) An ink for sheet offset (RI manufactured by Dainippon Ink and Chemicals, Inc.
Ans-G ink) 0.6 cc was used to print the surface of the cast coated paper once, and immediately after the printing, 2 minutes after the printing, and 4 minutes after the printing, the surface of the cast coated paper was superposed on the high-quality paper and a constant pressure was applied. The density of the ink transferred to the high-quality paper was observed and judged according to the following criteria. ⊚: Ink hardly transferred to the high-quality paper after 2 minutes. ◯: Ink hardly transferred to the high-quality paper after 4 minutes. Δ: The transfer density after 4 minutes is about half the ink transfer density immediately after printing. (Drying speed is slightly slow) x: The transfer density after 4 minutes is slightly thin with respect to the ink transfer density immediately after printing. (Drying speed is quite slow)

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

As is apparent from the results shown in Table 2, the coated paper for printing of the present invention was extremely excellent in folding crack resistance and ink setting property.

Claims (3)

[Claims] 1. A coated paper for printing, comprising a base paper and an undercoating layer and a topcoating layer containing a pigment and an adhesive as main components, wherein the base paper contains a cationic surfactant. And 15% by weight or more of the copolymer latex as an adhesive in the undercoating layer, based on 100 parts by weight of the pigment. 2. The coated paper for printing according to claim 1, wherein the cationic surfactant is a quaternary ammonium salt having at least one alkyl group having 16 or more carbon atoms. 3. The coated paper for printing according to claim 1 or 2, wherein the coated paper for printing is a cast coated paper.