JP2001329487A - Thinly coated paper having fabric hand of uncoated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide thinly coated paper that causes no troubles of paper peeling and occurrence of paper powder with retention of the opacity and excellent printability as it maintains the fabric hand of uncoated paper. SOLUTION: The objective thinly coated paper relating to this invention having a fabric hand of uncoated paper is produced by forming a coating layer including a pigment and an adhesive on the surface of the substrate paper in a grammage of <=64 g/m2 where the pigment includes 20-50 pts.wt. of titanium dioxide, while the adhesive is added in an amount of 100-300 pts.wt. to the amount of the pigment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lightly coated paper, and more particularly to a lightly coated paper having a texture of an uncoated paper.

[0002]

2. Description of the Related Art In recent years, the printing method has been changed from letterpress rotary printing to offset rotary printing. Offset printing refers to a method in which dampening water and ink are supplied to a printing plate, and then the ink is transferred to a rubber plate called a blanket, and then transferred to paper to perform printing.

[0003] Offset printing uses ink that has a higher tack than letterpress printing, and therefore has a large surface strength.
In addition, it is required to use paper having high water resistance. Because if the surface strength is low or the water resistance is low,
This is because fibers released from the sheet due to paper peeling or the like and pigments contained in the sheet accumulate on the blanket of the printing press or are mixed with ink, thereby causing blurring on the printing surface and causing trouble.

[0004] By the way, there is a tendency to reduce the weight of printing paper in general, and there is a demand for paper having high opacity after printing accompanying the reduction in weight. In order to increase the opacity of such lightweight paper, pigments such as white carbon, titanium dioxide, calcined kaolin, calcium carbonate, and urea formaldehyde resin have been used as internal fillers in the production of base paper.

However, the internal strength of the above-mentioned inorganic or organic pigments decreases the paper strength, causing a problem in that paper breakage occurs in the paper making process and the printing process.

[0006] In addition, due to the dampening solution or ink tacking during offset printing, fine fibers and internal pigments are released from the inside of the paper layer and deposited on the blanket. Had been a problem.

[0007] In order to cope with the above-mentioned problems such as paper cutting and blanket piling in lightweight paper, a surface coating agent of a water-soluble polymer such as starch, polyvinyl alcohol or polyacrylamide is applied to the surface of the paper. Was. By applying such a water-soluble polymer surface coating agent, the fibers on the paper surface and the internal pigment are adhered to each other to strengthen the paper layer, thereby increasing the surface strength and improving the water resistance. Because you can do it.

However, if the coating amount is increased in order to obtain sufficient surface strength and water resistance, a part of the surface coating agent is dissolved by dampening water during offset printing, and the paper surface becomes tacky called nappar. . As a result, there is a problem in that the paper surface sticks to the blanket during printing, which induces a paper break. In addition to the fact that the paper is lightweight, it was difficult to obtain a paper having high opacity.

On the other hand, in order to improve the opacity of the coated paper, titanium dioxide has been used as a pigment in the coated layer. In general, troubles such as paper peeling are less likely to occur on coated paper with a large amount of coating, but this problem is likely to occur on coated paper with a small amount of coating. Therefore, in order to prevent the above-mentioned problems such as peeling of paper and blanket piling in lightweight paper, even when titanium dioxide is used as a pigment, the application amount is often more than 6 g / m ² on both sides.

However, on the other hand, the texture of uncoated paper has been impaired. In the case where conducted at a coat weight of duplex 6 g / m ² or less to leave the texture such as non-coated paper, paper picking, blanket piling or the like occurs,
The coating amount was insufficient to obtain the effect of preventing such troubles.

[0011]

The object of the present invention is to provide a light-weight and low-coating material as described above by providing a trace amount coating layer containing an appropriate ratio of a pigment containing titanium dioxide and an adhesive on a base paper. Solved the problem of coated paper. In other words, a finely coated paper that does not cause paper peeling or paper dust trouble, has opacity, and is excellent in printability, and further provides a finely coated paper having a texture of an uncoated paper. It is.

[0012]

Means for Solving the Problems The present invention described in claim 1 is directed to a lightly coated paper having a product basis weight of 64 g / m ² or less in which a coating layer containing a pigment and an adhesive is provided on the base paper surface. The pigment contains 20 to 50 parts by weight of titanium dioxide, and the adhesive is added to the pigment in an amount of 100 to 300 parts by weight. It is paper.

In the present invention, titanium dioxide is used as a pigment 100
Of the parts by weight, the content of 20 to 50 parts by weight is that if the titanium dioxide is less than 20 parts by weight, the desired opacity is not obtained, and if it exceeds 50 parts by weight, problems such as blanket piling and powder dropping occur. Because.

The adhesive is used in an amount of 100 to 300 parts by weight per 100 parts by weight of the pigment.
The reason for adding the parts by weight is that the amount of the adhesive is
If the addition is less than 100 parts by weight, sufficient adhesive strength and water resistance cannot be obtained, causing paper dust trouble, etc., and if the addition exceeds 300 parts by weight, the transparency of the paper proceeds, and the desired opacity is obtained. This is because it is difficult to obtain.

According to the first aspect of the present invention, it is a lightly coated paper which is opaque and has excellent printability without causing paper peeling or paper dust trouble, and has a texture of uncoated paper. Could provide fine coated paper.

In the present invention, it is necessary that the coating layer is a coating layer containing a pigment containing titanium dioxide and an adhesive in an appropriate ratio. It need not be composed of only an adhesive. That is, other substances can be contained as long as the effects of the present invention are not impaired.
As described below, other substances include dyes, surface sizing agents, defoaming agents, water-resistant agents, various auxiliaries such as preservatives, and the like, but are not limited thereto. More preferably, the total weight of the pigment and the adhesive is 95% by weight or more of the weight of the coating layer. By adding the above-mentioned various auxiliaries,
The paper was colored, the water resistance was further improved, or the flexibility was improved.

The invention according to claim ² is the finely coated paper having the texture of uncoated paper according to claim 1, wherein the coating layer has a dry weight of 2 to 6 g / m ² on both sides.

The reason that the coating layer is ² to 6 g / m ² on both sides by dry weight is that the desired opacity cannot be obtained with less than 2 g / m ^{2 on} both sides.
Also, paper dust troubles occur, while 6g on both sides
/ m ² more than the texture of the uncoated paper is impaired, because if there is a limit on the weight of the final product is Mekata of that amount of the base paper is less, resulting in leading to Kamiryoku drop, printing process This is because a sheet break occurs due to, for example, the above. According to the invention described in claim 2, in addition to the features of the invention described in claim 1, it is possible to provide a finely coated paper having a more preferable texture of uncoated paper.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing the product of the present invention will be described. The pulp that is the main component of the base paper used in the present invention includes chemical pulp (such as bleached or unbleached NKP and LKP),
High-yield valves (GP, CGP, RGP, PGW, TMP, etc.), deinked waste paper pulp (DIP, etc.), etc. are used alone or mixed in any ratio.

Before the papermaking, paper-based fillers such as silica-based inorganic pigments such as synthetic silica and white carbon, and titanium dioxide, calcined kaolin, calcium carbonate, and urea-formaldehyde resin are added as needed. Can be.

Further, in the stock, a sizing agent such as a sulfuric acid band, a paper strength enhancer, a retention enhancer, a reinforced rosin sizing agent, an emulsion sizing agent, a water-proofing agent,
A generally known chemical for papermaking, such as an ultraviolet ray inhibitor, is added, and the paper is made by an ordinary papermaking machine.

In the case of the present invention, the basis weight of the base paper is 62 g / m ²
The desired effect is exhibited in the case of the following lightweight paper, and a lightly coated paper having a texture of an uncoated paper having a product basis weight of 64 g / m ² or less can be obtained.

As the pigment of the coating layer in the present invention, other than the above-mentioned titanium dioxide, for example, kaolin, calcined kaolin, calcium carbonate, and the like, as long as the effects of the present invention are not impaired.
Pigments known and used in the coated paper manufacturing field, such as calcium sulfate, magnesium carbonate, aluminum hydroxide, barium sulfate, zinc oxide, satin white, mica, and plastic pigments, can be appropriately used in combination.

The adhesive of the coating layer in the present invention includes:
For example, ordinary modified starches such as oxidized starch, etherified starch, esterified starch, and cationized starch, water-soluble cellulose compounds such as carboxymethylcellulose, methylcellulose and hydroxyalkylcellulose, styrene-butadiene copolymer latex, styrene-methacrylic acid Copolymer latexes such as ester copolymer latex,
Examples thereof include polyvinyl alcohol, polyacrylamides, and guar gum.

The coating liquid for a coating layer containing a pigment and an adhesive as described above (hereinafter referred to as a “coating liquid”) includes a dye, a surface sizing agent, a defoaming agent, Waterproofing agent,
It is prepared by adding various auxiliaries such as preservatives as needed and mixing and stirring.

The solid content concentration of the coating liquid can be appropriately adjusted according to the coating apparatus and the target coating amount, but is usually adjusted in the range of 3 to 40% by weight.

The method for forming the coating layer on the base paper is not particularly limited, and includes a size press, a blade metering size press, a rod metering size press, a gate roll coater, a blade coater, a bar coater,
A commonly known and used coating apparatus such as a rod blade coater and an air knife coater can be appropriately used.

For drying the coating layer, well-known and commonly used drying methods such as ordinary hot air, infrared rays, and heat cylinders are appropriately used.

After the coating layer is dried, it can be subjected to pressure treatment using a machine calender, a soft nib calender, a super calender or the like, if necessary.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples. Of course, the invention is not limited to these examples. Parts and% in the examples are parts by weight and% by weight, respectively, unless otherwise specified.

Example 1 [Preparation of base paper] Ratio of 90 parts of hardwood kraft pulp (LBKP) beaten by a refiner to a freeness (CSF) of 460 ml and 10 parts of softwood kraft valve (NBKP) beaten by a refiner to a freeness (CSF) of 600 ml Was prepared. Next, 14% of a talc (trade name: NTL / Nippon talc) / light calcium carbonate (trade name: TP-121S / Okutama Kogyo) = 50% / 50% mixed filler and cationic starch ( Product Name: HMS /
(Matsutani Chemical) 1.2%, Neutral rosin emulsion size (product name: NT-85 / Arakawa Chemical) 0.085%, sulfate band 0.5%, retention agent (product name: BMA-0 / Nissan Eka Chemicals) A base paper having a basis weight of 50 g / m ² was obtained by adding 0.045% (all in comparison with pulp solid content).

[Preparation of paints and coated papers] As pigments, 20 parts of titanium dioxide (trade name: A-110 / Sakai Chemical) and 40 parts of clay (trade name: KCS / ITC) and wet weight Urea phosphate esterified starch (trade name: MS4600 / Nippon Shokuhin Kako) is added as an adhesive to 40 parts of mixed pigment of 40 parts of mixed calcium carbonate (trade name: Hydrocarb 90 / Bibihoku Powder Chemical Industry) And further add water to make the solids concentration 20
% Paint was obtained. Then, on both surfaces of the base paper above 50 g / m ^2,
4g / m on both sides with dry weight using gate roll coater
In such a way that ² performs a coating, to obtain a fine coated paper.

Example 2 A finely coated paper was obtained in the same manner as in Example 1, except that 100 parts of urea phosphorylated starch was added as an adhesive in the preparation of the coating material of Example 1.

Example 3 A finely coated paper was obtained in the same manner as in Example 1, except that 300 parts of urea phosphorylated ester was added as an adhesive in the preparation of the coating material of Example 1.

Example 4 In the preparation of the paint of Example 1, titanium dioxide 2 was used as a pigment.
A slightly coated paper was obtained in the same manner as in Example 1, except that 100 parts of a mixed pigment of 0 parts and 80 parts of clay was used.

Example 5 In the preparation of the paint of Example 1, titanium dioxide 5 was used as a pigment.
Except that the mixed pigment of 0 parts and 50 parts of clay was 100 parts,
A finely coated paper was obtained in the same manner as in 1.

Example 6 A slightly coated paper was obtained in the same manner as in Example 1 except that the coated paper was prepared so that the dry weight was 2 g / m ² on both sides in the preparation of the coated paper.

Example 7 A slightly coated paper was obtained in the same manner as in Example 1 except that the coating was performed so that the dry weight was 6 g / m ² on both sides.

Comparative Example 1 A slightly coated paper was obtained in the same manner as in Example 1 except that 70 parts of urea phosphorylated starch was added as an adhesive in the preparation of the coating material of Example 1.

Comparative Example 2 A slightly coated paper was obtained in the same manner as in Example 1 except that 400 parts of urea phosphorylated ester was added as an adhesive in the preparation of the coating material of Example 1.

Comparative Example 3 In the preparation of the paint of Example 1, titanium dioxide 1 was used as a pigment.
A slightly coated paper was obtained in the same manner as in Example 1, except that 100 parts of a mixed pigment of 0 parts and 90 parts of clay was used.

Comparative Example 4 In the preparation of the paint of Example 1, titanium dioxide 6 was used as a pigment.
Except that the mixed pigment of 0 parts and 40 parts of clay was 100 parts,
Fine coated paper was obtained using the same machine as 1.

Comparative Example 5 A slightly coated paper was obtained in the same manner as in Example 1 except that the coating was performed so that the dry weight was 1 g / m ² on both sides.

Comparative Example 6 A slightly coated paper was obtained in the same manner as in Example 1 except that the coating was performed so that the dry weight was 7 g / m ² on both sides.

Comparative Example 7 The base paper of Example 1 was coated with only urea phosphorylated ester starch without adding a pigment to a dry weight of 2.5 g / m ² on both sides to obtain a paper.

The following items were evaluated for the finely coated papers of the examples and comparative examples thus obtained, and the results obtained are shown in Table 1.

[Printing Strength] Using an RI-II type printing machine (manufactured by Meiji Seisakusho), using a TV = 20 manufactured by Toyo Ink Co., Ltd.
Printing was carried out at a constant 4 cc, and the degree of picking on the printing surface was visually evaluated. In the table, △ x indicates that ○ = no occurrence, △ = occurs, and X = significant occurrence.

[Print-through evaluation] Using an ink for rotary offset printing (trade name: LEOECOO black / Toyo Ink) using an RI-II type printing machine (manufactured by Meiji Seisakusho), printing was performed at a constant ink amount of 1.0 cc. Back side after printing (opposite side of printing side)
Was visually evaluated relative to the degree of print-through. ○ in the table
Δx represents 、 = very good, ＝= good, Δ = slightly bad, × = very bad.

[Evaluation of Paper Texture] The appearance and feel of the paper were evaluated relative to the paper texture. In the table, △ indicates the texture of high-quality paper (uncoated paper), △ indicates the feel of coated paper, and X indicates the texture of coated paper.

[0050]

[Table 1]

As is clear from Table 1, the finely coated papers obtained in Examples 1 to 7 according to the present invention have good print strength and print-through, and have a good texture of uncoated paper. had.

[0052] In Example 1-7, when the basis weight of the base paper is 50 g / m ^2, ie, product basis weight exemplarily shows a case of 52~56g / m ^2, the product basis weight If it was 64 g / m ² or less, the printing strength and print-through were also good, and the texture was like uncoated paper.

[0053]

According to the first aspect of the present invention, it is a lightly coated paper which is opaque and has excellent printability without causing paper peeling or paper dust trouble, and further has a texture of an uncoated paper. Could be provided. In addition, it was possible to provide a finely coated paper having the texture of an uncoated paper in which the paper was colored to further improve the water resistance or the flexibility, etc. according to the application.

According to the second aspect of the present invention, it is possible to provide a finely coated paper having a more favorable texture of uncoated paper.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Yoshikawa 57 Enomachi, Niigata City, Niigata Prefecture Hokuetsu Paper Mills Niigata Mill (72) Inventor Tsutomu Sato 3-5-1 Nishi Zao, Nagaoka City, Niigata Prefecture Hokuetsu Paper Mills Co., Ltd. F-term in company laboratory (reference) 4L055 AA03 AC06 AG11 AG12 AG19 AG26 AG48 AH01 AH02 AH37 AJ04 BE07 BE08 EA32 FA11 GA19

Claims (2)

[Claims] 1. A finely coated paper having a product basis weight of 64 g / m ² or less, wherein a coating layer containing a pigment and an adhesive is provided on the surface of a base paper, wherein the pigment contains 20 to 50% by weight of titanium dioxide. A fine coated paper having a texture of an uncoated paper, wherein the adhesive is added in an amount of 100 to 300 parts by weight based on the pigment. 2. A lightly coated paper having a texture of an uncoated paper according to claim 1, wherein the coating layer has a dry weight of 2 to 6 g / m ² on both sides.