JPH0813390A - Coated paper for printing - Google Patents

Abstract

(57) [Abstract] [Purpose] Production of a coated paper for printing, which has practically sufficient printability and has high gloss, and a coated paper for printing, which can easily and inexpensively produce a certain quality. Providing a method. In a coated paper for printing having a pigment-containing layer on at least one surface of a support, thermoplastic polymer latex particles having an average particle size of 100 nm or less and a second-order transition temperature of 80 ° C. or more are provided on the pigment-containing layer. A coated paper for printing, comprising a surface layer containing the surface layer, the surface layer being not calendered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-gloss coated paper having excellent printability.

[0002]

2. Description of the Related Art Coated paper having a coating layer composed of a pigment and its binder is used as high-grade printing paper,
In addition to printability such as ink absorbency and coating layer strength, the gloss of the coating layer surface is an important factor. By the way, if the surface of the coating layer is pressed and smoothed in order to increase the glossiness, the voids of the coating layer are inevitably collapsed and the ink absorbing ability is lowered. Also,
When a large amount of water-soluble or water-dispersible polymer substance such as polymer latex used as a binder of pigment for increasing glossiness is used, coating layer strength and gloss are improved but voids of coating layer still remain. There is a part where gloss and printability conflict with each other, such as a decrease in ink absorption capacity. In this way, in coated paper, the type and composition of pigments and adhesives, the coating amount of the paint, the degree of smoothing treatment, etc. are determined in order to obtain a proper balance between gloss and printability. Yet another technique is needed to obtain good high gloss papers. The glossiness of the coated paper for printing is generally higher in the order of the slightly coated paper, the coated paper, the art paper, the super art paper, and the cast coated paper, and the high gloss in the present invention is equivalent to the super art paper, Alternatively, it refers to a glossiness higher than that, and therefore high gloss paper is used to mean a coated paper for printing having a glossiness higher than that of super art paper.

Conventionally, there is a method using a cast coater for producing high gloss paper. This method is a method in which a wet coating layer composed of a pigment and a binder is pressed against a mirror-finished cast drum and heated and dried, which is several steps slower than the production speed of general art paper, coated paper or lightly coated paper. There is a point.

Further, a method of utilizing a heating calendar is known regardless of the cast drum. For example, in JP-A-56-68188, JP-B-64-10638 and JP-B-64-11758, a coating layer obtained by mixing and drying a pigment and a polymer latex or a water-soluble polymer resin is disclosed. A method of heat calendering is disclosed. In these, a polymer latex having a glass transition temperature of 5 ° C. or 38 ° C. or higher is coated on a support, and then,
The coating layer is treated with a heating calendar in which the heating temperature is set so that the temperature of the coating layer is higher than the glass transition temperature of the latex used. This method is a simple method, has good productivity, and is suitable for the production of ordinary coated paper, but it is not sufficient in terms of gloss, and cast coated paper and of course more than super art paper can be used. No, it is not possible to obtain a gloss comparable to cast coated paper.

Further, as another method, JP-A-59-22
There is a method disclosed in Japanese Patent No. 683. This method is a technique in which two or more kinds of polymer latexes having different minimum film forming temperatures are used in combination and dried on a single sheet or a sheet having a pigment coating layer, and a calendar is used for smoothing, if necessary. When latexes having different minimum film forming temperatures are used together and dried, fine cracks are generated on the surface of the coated paper, and good ink absorbency can be obtained without impairing gloss. In this technique, an important point is that fine cracks are produced on the surface of the coated paper, and for that purpose, the drying conditions must be carefully monitored. That is, it is necessary to set the drying conditions such that the latex having a low minimum film-forming temperature is completely melted while the latex having a high minimum film-forming temperature is partially melted. However, as is well known, the drying conditions are generally liable to change due to a number of factors, and when considering the industrial application of this technology, it is true that it is always and uniformly maintained throughout the manufacturing process. It's impossible. Therefore, it is extremely difficult to maintain a constant and stable quality.

[0006]

In view of the above situation, the present invention provides
An object of the present invention is to provide a coated paper for printing which has a practically sufficient printability and has a high gloss, and a method for producing a coated paper for printing which can easily and inexpensively produce a certain quality.

[0007]

The inventors of the present invention previously disclosed in Japanese Patent Application No. 1-307888 (Japanese Patent Application Laid-Open No. 3-167396) a coated paper for printing, a pigment coated layer on a support. The second-order transition temperature is 80 on the pigment coating layer of the substrate provided with
It has been proposed that the above-mentioned problems can be solved by providing a surface layer made of a thermoplastic polymer latex having a temperature of ℃ or higher and calendering the surface layer at a temperature not higher than the second-order transition temperature. After that, as a result of further research, it was found that the above-mentioned problems can be solved by using a thermoplastic polymer latex having an extremely small particle size without necessarily carrying out calendering treatment.

That is, according to the present invention, in a coated paper for printing having a pigment-containing layer on at least one surface of a support, the pigment-containing layer has a mean particle size of 100 nm or less and a second-order transition temperature of 80 ° C. or more. The present invention relates to a coated paper for printing, wherein a surface layer containing plastic polymer latex particles is provided, and the surface layer is not calendered.

In general, a printing substrate is paper, synthetic paper,
Plastic films, non-woven fabrics, etc. are used, with paper being the most common. The paper includes pigment-coated paper such as art paper, coated paper, slightly coated paper and coated white balls, and non-coated paper such as high-quality paper, medium-quality paper, newspaper, simple gloss paper and special gravure paper.

In the present invention, the substrate used for achieving both high gloss and printability must be a substrate having a pigment-containing layer provided on a support, among the above-mentioned substrates for printing.
The support is not particularly limited as long as the pigment-containing layer layer is provided thereon, and uncoated paper such as medium-quality paper and high-quality paper is suitable. The method for providing the pigment-containing layer on the uncoated paper can be sufficiently achieved by the usual method for producing pigment-coated paper, but depending on the desired quality, the pigment in the paint, the type of binder, or the pigment and binder may be used. The amount ratio of is appropriately changed before use. Pigment coated paper has a coating amount of 2-40g on one side.
/ M ^{2 is} a single-sided or double-sided coated paper. After pigment coating, a thermoplastic polymer latex is overcoated on this pigment coating layer to form a surface layer.However, the pigment coating layer may be smoothed with a super calendar or gloss calendar before the top coating. Absent.

When the thermoplastic polymer latex-containing layer is directly provided on the non-coated paper without providing the pigment-containing layer, the printability is secured, but the expected high glossiness cannot be obtained. .

When synthetic paper or plastic film is used as the support and the thermoplastic polymer latex is directly provided on the support without providing the pigment-containing layer,
Although the glossiness can obtain a desired value, it is unsuitable because the drying property of the ink is insufficient and the printability is poor.

The thermoplastic polymer latex used in the present invention is an emulsion of a polymer or copolymer exhibiting thermoplasticity, having a second-order transition temperature of 80 ° C. or higher and an average particle size of 100 nm or less. (Hereinafter, an emulsion composed of a polymer or copolymer showing thermoplasticity is simply referred to as a polymer latex).
In the case of core-shell type latex, the second-order transition temperature of the shell portion must be 80 ° C. or higher. 8
The type of monomer constituting the polymer latex and the manufacturing method are not limited as long as the second-order transition temperature is 0 ° C. or higher.
Examples of preferably used monomers include styrene and its derivatives, vinylidene chloride, acrylic acid or methacrylic acid ester.

The upper limit of the second-order transition temperature of the polymer latex is not particularly limited and is mainly determined by the type of the monomer used in the production of the polymer latex and additives such as plasticizers, and the upper limit is usually about. It is 130 ° C.

When a polymer latex having a second-order transition temperature of 80 ° C. or lower is used, adhesion to a calender roll occurs during calendering, the glossiness of the coated paper obtained is insufficient, and the peel strength of the surface layer. Is weakened, and problems such as lack of printability occur, and the object of the present invention cannot be achieved.

The particle size of latex generally used in the field of paper coating is generally smaller than that of other uses such as paints, and the average particle size is often about 200 nm to 1000 nm. The coalesced latex has a smaller average particle size of less than 100 nm. Average particle size 100n
By using a material of less than m, it is possible to obtain a gloss as high as that of a general coated paper which is smoothed by a gloss calendar or a super calender without special smoothing treatment. By smoothing the coating layer, it is possible to obtain a printing paper having extremely high gloss. The smoothing treatment may be a super calender or a gloss calender used for the smoothing treatment of general coated paper, and these may be used in combination. However, the calendering conditions are important, and it is necessary to carry out the treatment at a temperature below the second-order transition temperature of the polymer latex used as the surface layer. The calendering temperature is not particularly limited as long as it is a temperature below the second-order transition point, but it is 5 ° C. or more, preferably 1 or more than the second-order transition temperature of the polymer latex.
A temperature as low as 0 ° C to 30 ° C is suitable. In the smoothing treatment, when the treatment temperature is high and the temperature of the layer coated with the polymer latex becomes higher than the second-order transition humidity of the polymer latex used, the latex melts and forms a film, and the ink acceptability is extremely lowered. , The object of the present invention cannot be achieved. Further, when the polymer latex melts or begins to melt, the adhesiveness of the coating layer increases, causing troubles such as adhesion between the smoothing roll and the coating layer, making the smoothing treatment itself impossible.

Therefore, it is a preferred method to add a proper amount of lubricant to the polymer latex of the present invention. Among the lubricants that are generally used for molding and processing plastics, those used as external lubricants are suitable for the present invention. As the external lubricant, those described on pages 945 and below in the Supplementary Plastics and Rubber Additives Handbook (published on July 0, 1989 by Kagaku Kogyo Co., Ltd.) are used. For this purpose, it is preferable to use one selected from stearic acid and its derivative, oleic acid and its derivative, polyethylene wax emulsion, or a combination thereof. The blending amount of the lubricant is determined by the type of the lubricant and the polymer latex of the present invention, the condition and degree of the smoothing treatment, the amount and type of other additives, and the like. It is suitable to use about 5 to 40% by weight of the surface layer paint containing coalesced latex particles, and more preferably 10 to 25%.
% By weight.

The polymer latex of the present invention is usually applied alone on the pigment coating layer, but within the range not impairing the purpose of the present invention, in addition to the above-mentioned lubricant, plastic pigment, natural or synthetic resin binder, flow control. A surface layer coating material may be prepared by appropriately combining and mixing agents, defoaming agents, colorants, inorganic white pigments and the like.

The plastic pigment referred to in the present invention is
There are synthetic polymer particles mainly composed of polystyrene and having an average particle size of 100 nm or more, which have no substantial binding force by themselves, and have some binding force. An example of the former is ROHM &HAAS's hollow plastic pigment, low-paque OP.
84, and an example of the latter is Ni manufactured by Nippon Zeon Co., Ltd.
There is polLX407BP. When these plastic pigments are used in combination with the polymer latex of the present invention, 60% by weight or less is an appropriate range, preferably 20 to 40% by weight, based on the polymer latex of the present invention. By using a plastic pigment, gloss and surface strength can be adjusted.

In the present invention, a so-called binder is basically not used. However, in order to adjust the surface strength of the coating layer, a small amount of natural or synthetic resin binder for general coating may be used, but the amount used should be such that surface tackiness does not occur. is there. The types of additives such as paint fluidity regulators, defoamers, colorants, and inorganic white pigments are used for general paper. It should be no more.

The surface layer coating material thus obtained is
It is applied on the pigment coating layer to form a surface layer. The coating amount can be appropriately adjusted so as to obtain desired properties,
If the coating amount is too large, not only the cost will increase, but also the ink absorbency will decrease and the ink setting will become insufficient, and the undesirable tendency such as the strength of the surface layer will decrease, so too much amount will result. It is not a good idea to apply it, and usually 0.1 g / m ² or more on one side, preferably 0.1.
A coating amount of about 3 to 3 g / m ² is sufficient.

The surface layer coating material can be applied by a blade coater, a roll coater, an air knife coater, a bar coater, a gravure coater, a flexo coater or the like which is usually used in the field of paper coating. When the polymer latex of the present invention is used, the drying after coating does not require any special condition setting, and an optimum surface layer can be obtained under the drying conditions used in the production of ordinary coated paper.
For example, even when drying with hot air of about 150 ° C., the temperature of the surface layer is at most 80 ° C., and the second-order transition temperature of the polymer latex of the present invention is 80 ° C. or higher,
The latex does not melt to form a film.

[0023]

The reason why the coated paper for printing of the present invention has practically sufficient printability and high gloss is not clear, but an electron microscope of the surface gloss layer of the coated paper obtained by the present invention. It is inferred as follows from the observations at.

An electron micrograph of the surface layer of the coated paper of the present invention is shown in FIG. As is apparent from FIG. 1, the surface layer is not a continuous uniform film formed by melting the polymer latex, but has a structure in which polymer latex particles of tens of nanometers are densely arranged with respect to each other. This is because the second-order transition temperature of the polymer latex of the present invention is as high as 80 ° C. or higher, so that under normal drying conditions, the shape of the polymer particles is maintained without melting each other, and then a calender treatment is carried out if necessary. Also, as long as the temperature of the surface layer is lower than the second-order transition point of the polymer latex, the latex particles do not melt to each other to form a continuous film and are fixed while leaving the particle shape. ing. Therefore, it is considered that there are a large number of interstices between the particles of the polymer latex, the printing ink is held between the interstices, and at the same time passes through the capillaries between the particles to reach the lower pigment coating layer and be absorbed.

Further, according to the conventional theory, latex as shown in FIG. 1 which does not melt with each other and retains the particle shape should have no strength as a film, but the surface gloss layer of the present invention is practical. It has sufficient surface strength. The reason is completely unknown at present, but the second-order transition temperature is 8
It is considered that the polymer latex of the present invention having a temperature of 0 ° C. or higher has a certain degree of hardness even during calendering, and if such a latex is applied on the pigment coating layer and calendered, it is likely that the latex will be dense. It is considered that this is due to the effects of the physical properties of the pigment coating layer, such as elasticity and elasticity, the physical properties of the polymer latex determined by the hardness, particle size, coating amount, etc., and the chemical affinity between the latexes.

From the conventional common sense that a continuous surface that is as uniform as possible is required to obtain high gloss, the surface of the polymer latex coating layer of the present invention is still in a particle shape. However, it was quite unexpected and surprising that high gloss was obtained. Probably related to the fact that the particle size of the polymer latex is small and that the polymer latex mainly fills the concave portion of the pigment coating layer,
It is assumed that the surface layer as a whole was optically smoothed.

However, the state of the surface layer of the coated paper for printing in Comparative Example 1 which will be described later also shows the effect of the present invention, since the polymer latex retains the particle shape as in FIG. It is strongly speculated that another factor is involved in the mechanism of action, but it is unclear what that is.

Further, in the production of the coated paper for printing, the drying conditions and the calendering conditions are the same as the production conditions of the ordinary coated paper, so that a constant quality can be obtained without impairing the productivity.

[0029]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to the examples. All parts and% shown in the examples mean parts by weight and% by weight unless otherwise specified.

[Production of Polymer Latex] (Production Example 1) 300 parts of water and 9 parts of sodium dodecylbenzenesulfonate were placed in a four-necked flask equipped with a stirrer, a thermometer, a cooler, a dropping funnel and a nitrogen gas introducing tube. 80 parts of styrene and α- of polyoxyethylene phenol ether (10 mol of ethylene oxide added) were mixed in the mixture.
10 parts of methyl styrene, 100 parts of methyl methacrylate,
60 parts of a monomer mixture of 10 parts of methacrylic acid was charged, the temperature was raised to 60 ° C. while substituting with nitrogen, 7.2 parts of 20% ammonium persulfate aqueous solution and 4.8 parts of 20% anhydrous sodium bisulfite aqueous solution were added, and the mixture was added for 60 minutes. Polymerized. Then 20%
After adding 10 parts of an aqueous solution of ammonium persulfate, the remaining 140 parts of the monomer mixture was added dropwise over 1 hour. 90 ° C
Polymerization was completed by keeping the temperature at 4 ° C for 4 hours,
An ethylenic monomer copolymer latex (A) having an average particle size of 75 nm and a solid content of 39% was obtained.

(Production Example 2) In a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet tube, 310 parts of water and Hitenol N-08 (polyoxyethylene nonylphenol manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) Ether sulfate salt)
5.6 parts, 48 parts of styrene, 19 parts of methyl methacrylate, 8 parts of ethyl methacrylate, 2.5 parts of divinylbenzene and 2.5 parts of methacrylic acid were charged, and the temperature was raised to 70 ° C. while substituting with nitrogen, and the mixture was heated to 16%. Aqueous potassium persulfate solution 5
Polymerization was terminated by maintaining the mixture at 85 ° C. for 4 hours to obtain an ethylenic monomer copolymer latex (B) having a second transition temperature of 85 ° C. and an average particle size of 75 nm and a solid content of 21.2%.

(Production Example 3) 88 parts of styrene, 38 parts of methyl methacrylate, n-methacrylic acid were added to the monomer of Production Example 1.
The same operation as in Production Example 1 was carried out except that 70 parts of butyl and 4 parts of methacrylic acid were used to obtain a copolymer latex (C) having a second transition temperature of 68 ° C., an average particle size of 70 nm and a solid content of 39%.

[Production of base material (pigment-coated paper)] 70 parts of primary kaolin, 30 parts of fine ground heavy calcium carbonate, styrene-
Butadiene copolymer latex 13 parts (solid content), 35
A coating liquid for coated paper having a solid content of 64% and containing 5 parts (solid content) of a starch solution was prepared. The obtained coating liquid has a basis weight of 127 g.
/ M ² high-quality coated base paper with a dry weight of 14 g / m on one side
^It was coated with a blade coater at a coating speed of 500 m / min so as to be ^2, and dried to obtain a topcoating base material (pigment coated paper) having a pigment coating layer with a water content of 5.5%.

Example 1 100 parts (solid content) of the copolymer latex (A) having a second-order transition temperature of 107 ° C. and an average particle size of 75 nm was diluted with water to obtain a coating for surface layer coating having a solid content of 30%. The liquid was adjusted. The obtained coating liquid was applied to the above base paper (pigment-coated paper) with a blade coater at a coating speed of 500 m / min so that the dry weight on one side was 1.6 g / m ² , dried, and dried. 6.5% of printing coated paper was obtained.

<Comparative Examples 1 and 2> In Comparative Example 1, the pigment coated paper which is the base paper used in Example 1 is used as it is as a coated paper for printing. In Comparative Example 2, a super calender consisting of a chilled roll and a cotton roll was used, the pigment-coated surface of the pigment-coated paper of Comparative Example 1 was applied to a metal roll, and 2 nips were passed at a nip pressure of 180 kg / cm. The coated paper for printing was used.

<Example 2 and Example 3> In Example 2, the composition of the coating liquid for coating the surface layer used in Example 1 was changed to a copolymer latex having a second-order transition temperature of 107 ° C. and an average particle size of 75 nm. (A) 70 parts (solid content), 30 parts (solid content) of plastic pigment (Rohm & Haas Rhopaque OP84)
Example 1 except that the composition has a solid content of 30%
A coated paper for printing manufactured by the same method as described above. Example 3
Example 1 except that the coating liquid for coating the surface layer used in Example 1 was 30 parts of copolymer latex (A) and 70 parts of plastic pigment (Rohm & Haas Ropeke OP84) (solid content). It was manufactured in the same manner as.

<Examples 4 and 5> Second-order transition temperature 10
Copolymer latex (A) 6 having an average particle size of 75 nm at 7 ° C.
To 5 parts (solid content), 25 parts (solid content) of plastic pigment (Rohm & Haas Rhopaque OP84), a lubricant prepared by mixing 5 parts (solid content) of polyethylene wax emulsion and 5 parts (solid content) of calcium stearate was added. Then, a coating liquid for surface layer coating having a solid content of 30% was prepared.
The obtained coating liquid was applied onto the above-mentioned base paper (pigment-coated paper) at a coating speed of 500 m / m so that the dry weight on one side was 1.6 g / m ^2.
It was coated with a blade coater for a minute and dried to obtain a coated paper having a surface layer with a water content of 6.5%. Using a super calender consisting of a chilled roll and a cotton roll, the coated surface is placed on a metal roll and the chilled roll temperature is set to 8
The coated paper for printing of Example 4 was obtained by passing 2 nip papers at 2 ° C. and a nip pressure of 180 kg / cm. In Example 5, the composition of the coating liquid for surface coating of Example 4 was changed to 25 parts (solid content) of copolymer latex (A) and 65 parts (solid content) of plastic pigment (Rohm & Haas Rhopaque OP84).
The coated paper for printing manufactured in the same manner as in Example 4 except for the above.

<Examples 6, 7, 8 and Comparative Example 3> 90 parts (solid content) of copolymer latex (A) having a second-order transition temperature of 107 ° C. and an average particle size of 75 nm, 5 parts of polyethylene wax emulsion (solid content) ) And 5 parts of calcium stearate (solid content) were added to prepare a coating solution for surface layer coating having a solid content of 30%. The obtained coating liquid was applied to the base paper (pigment-coated paper) with a dry weight of 1.6 g / m ² on one side.
To obtain a coated paper having a surface layer with a water content of 6.5% by coating with a blade coater at a coating speed of 500 m / min and drying. Using a super calender consisting of a chilled roll and a cotton roll, the coated surface of the coated paper is applied to a metal roll, the chilled roll temperature is 65 ° C., the nip pressure is 180 k.
The coated paper for printing of Example 6 was obtained by passing 2 nip papers at g / cm. Example 7 was a chilled roll adjusted to a temperature of 82 ° C. Separately, this surface coated paper using a gloss calendar consisting of a chilled roll and a heat-resistant rubber roll,
Applying the coated surface to a metal roll, nip pressure 100kg / cm
At 2 nip, the coated paper for high gloss printing was obtained. The temperature of the chilled roll was adjusted to 95 ° C., which is referred to as Example 8. The temperature is higher than the second-order transition temperature of the copolymer latex, 120.
What was adjusted to ° C was set as Comparative Example 3.

<Examples 9, 10, 11> In Example 7, the coating amount of the surface layer was 0.7 g / m ² , 2.8 g / m ² .
m ² , 5.5 g / m ² was used in Example 9, respectively.
It was set to 10, 11.

<Examples 12 and 13, Comparative Example 4> 80 parts (solid content) of copolymer latex (B) having a second-order transition temperature of 85 ° C. and an average particle size of 67 nm, and 10 parts (solid content) of polyethylene wax emulsion. Calcium stearate 10
Part (solid content) mixed with a lubricant, solid content 20%
The coating liquid for coating the surface layer of was prepared. The obtained coating liquid was applied to the base paper (pigment-coated paper) with a dry weight of 1.2 g / m on one side.
^It was coated with a blade coater at a coating speed of 500 m / min so as to be ^2, and dried to obtain a coated paper having a surface layer with a water content of 6.5%. The coated paper was applied to a metal roll with a super calender consisting of a chilled roll and a cotton roll, and was passed through 2 nips at a nip pressure of 180 kg / cm to obtain a coated paper for printing. Chilled roll temperature 6
Example 12 was adjusted to 5 ° C, and Example 13 was adjusted to 82 ° C. Separately, using a gloss calender consisting of a chilled roll and a heat-resistant rubber roll, this surface-coated paper is applied to a metal roll with the coated surface at a chilled roll temperature of 120 ° C. higher than the second-order transition temperature of the copolymer, and a nip pressure of 100 kg / Comparative example 4 in which 2 nip paper is passed in cm
And

<Comparative Examples 5 and 6> As a polymer latex for coating the surface layer, the second-order transition temperature was 68 ° C. and the average particle size was 70 nm.
A coated paper for printing was obtained in the same manner as in Example 6 except that the copolymer latex (C) of Example 1 was used and the dry weight of one surface of the surface coating layer was 1.4 g / m ² . The temperature of the chilled roll was adjusted to 65 ° C., which is lower than the second transition temperature, and Comparative Example 5, and the temperature of 95 ° C., higher than the second transition temperature, was used as Comparative Example 6.

<Comparative Example 7> No pigment coating layer is provided,
On the basis weight of 127 g / ^{m 2} high-quality paper, using a direct copolymer latex (B), except that the 2.6 g / ^{m 2} coated at a dry weight of the surface coating for coated liquid, as in Example 13 A coated paper for printing was obtained in the same manner.

Tables 1 and 2 show the copolymer latexes used in Examples and Comparative Examples and the surface roll temperature of the metal roll during calendering. Tables 3 and 4 show the results of the quality evaluation test of the coated paper thus obtained. The evaluation items and test methods described in the horizontal columns of Tables 3 and 4 are as follows.

* White paper glossiness: Measured by a 60 ° reflection method using a Murakami type gloss meter. In the case of 75 ° reflection which is usually used in the glossiness test, it is difficult to make a difference when the glossiness is high. As standard of white paper glossiness, general coated paper (CT: NPi coat manufactured by Nippon Paper Industries Co., Ltd.), super art paper (SA: S manufactured by Kanzaki Paper Co., Ltd.)
A Kinto) and cast coated paper (CC: Kanzaki Paper Co., Ltd.)
The reflectance measurement value of 60% and 75 ° of Mirror Coat Platinum Co., Ltd.) is shown. The present invention has a gloss higher than that of general coated paper. * Printing glossiness: Printing was performed using a RI-II type printing tester, and measured with a Murakami type gloss meter by a 75 ° reflection method. * Ink set: The speed of ink setting is RI-II.
Printing was performed using a pattern printing tester, a blank sheet was pressed against the printed surface after printing, and the ink transfer to the blank sheet was visually evaluated.
The evaluation criteria were ◯ when there was no ink transfer to the white paper, Δ when partial ink transfer occurred, and x when significant ink transfer occurred. * Dry pick: This is a test showing the peel strength of the surface of the coated paper for printing, and the ink tack No. with high tack by the RI-II type printing tester. Printing was performed using 20 inks, and the degree of picking was visually evaluated. No picking is indicated by O, partial picking occurs by Δ, and marked picking occurs by X. * Gravure printability: Printed using a gravure printing tester (made by Kumagai Riki Co., Ltd.) with halftone dot gravure on the plate, and indicated as a percentage (%) of the total number of halftone dots generated. .

[0045]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

As can be seen from Tables 1 to 4, the coated paper for printing of the present invention exhibits a gloss level comparable to that of coated paper even without calendar treatment, and also has printability such as ink setting and dry picking. Very good. By performing the smoothing process with a calendar, the glossiness is higher than that of the super art paper, and the paper has a high gloss.
The printability such as ink setting, dry pick, miss dot rate, etc. is also extremely excellent or practical. In addition, the state of adhesion of the polymer latex to the calender roll during calendering, which is an index of ease of manufacture, is either good or practical.

On the other hand, the comparative examples all have insufficient glossiness, and one of the indexes showing the printability is bad, and the adhesion to the calendar roll, which is the index showing the ease of production. Is insufficient, and it is understood that the object of the present invention is not achieved.

[0048]

According to the present invention, a pigment coating layer is provided on a substrate, and a polymer latex having a second-order transition temperature of 80 ° C. or higher is applied on the pigment coating layer and dried to form a surface layer. By doing so, it is possible to obtain a coated paper having a gloss equivalent to that of coated paper without performing a smoothing treatment and having excellent printability such as ink absorbency and surface strength. Furthermore, by the method of calendering the surface layer at a temperature not higher than the second-order transition temperature of the polymer latex, a high gloss paper of super art paper or higher can be obtained, and at the same time, ink absorbency, surface peel strength, misdot ratio, etc. The printability is also sufficient for practical use, and since it does not adhere to the calender rolls, the productivity is increased and the production can be performed efficiently.

[Brief description of drawings]

FIG. 1 is a surface electron micrograph of a coated paper for printing of Example 1.

Claims (6)

[Claims] 1. A support having a pigment-containing layer on at least one surface thereof, the pigment-containing layer having an average particle size of 100 nm or less,
A coated paper for printing, characterized in that a surface layer containing thermoplastic polymer latex particles having a second-order transition temperature of 80 ° C. or higher is provided, and the surface layer is not calendered. 2. The surface layer is a surface layer containing a mixture of the thermoplastic polymer latex particles and a plastic pigment having an average particle size of 100 nm or more, wherein the thermoplastic polymer latex particles are 40% by weight of the mixture. %. The coated paper for printing according to claim 1, which is at least%. 3. The coated paper for printing according to claim 1 or 2, wherein the coating amount of the surface layer is 0.3 to 4 g / m ² . 4. The coated paper for printing according to claim 1, 2 or 3, wherein the surface layer contains a lubricant in an amount of 5 to 40% by weight of the surface layer. 5. A pigment-containing layer is provided on at least one surface of a support, and the pigment-containing layer has an average particle size of 100 nm or less.
A surface layer containing thermoplastic polymer latex particles having a second-order transition temperature of 80 ° C. or more and a plastic pigment having an average particle size of 100 nm or more is provided, and the surface layer has a temperature not higher than the second-order transition temperature of the polymer latex particles. A coated paper for printing, which is characterized by being subjected to a calendar treatment in. 6. The coated paper for printing according to claim 5, wherein the surface layer contains 5 to 40% by weight of the surface layer of a lubricant.