JP2005163211A - Coating liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a coating liner having an excellent printing gloss and a hardly breakable coated layer. <P>SOLUTION: The coating liner is a coating liner equipped with a coated layer obtained by coating the surface of base paper subjected to surface smoothing with a coating containing inorganic pigment, organic pigment and a binder in 3-8 g/m<SP>2</SP>and has ≥16% of white paper gloss of 75 degree measured by JIS-P8142. The coating liner has excellent printing gloss, has a hardly breakable coated layer in bending, beautiful white paper appearance and printing appearance and is useful as a liner for decorative corrugated board. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coating liner. In particular, the present invention relates to a coating liner having good printing gloss and being hard to break when coated. The coated liner of the present invention has a beautiful white paper appearance and printed appearance, and can be suitably used as a liner for cosmetic cardboard.

  Cardboard boxes have been widely used for transportation and storage of goods, but in recent years, products packed in cardboard boxes are displayed as they are in stores and sold. For example, a cosmetic cardboard box on which multicolor printing has been performed can display merchandise faithfully, and has the effect of attracting people's eyes. For this reason, high aesthetics, that is, printability, is required for the cardboard liner.

Therefore, in order to impart aesthetic properties to the cardboard box, it has been attempted to improve the printability of the cardboard liner. The coating liner developed so far is manufactured, for example, by applying a coating agent mainly composed of an inorganic pigment and a binder to the surface of the base paper. Normally, such liners are produced by coating of about ^10g / ^{m 2 ~30g} / m 2 on the surface of the base paper a coating agent. Since the liner manufactured in this way has a large coating amount of the coating agent, the thickness of the coating layer increases. For this reason, the coating layer in the bent portion is likely to be broken during box-making of the cardboard box.

  For this reason, the ink printed on the bent portion loses its cosmetic properties by being cracked together with the coating layer when bent. In order to solve this problem, it is conceivable to reduce the thickness of the coating layer by reducing the coating amount of the coating agent.

  By reducing the coating amount of the coating agent, it is possible to improve the cracking of the bent portion, but on the other hand, the unevenness on the surface of the base paper cannot be sufficiently covered by the coating agent. For this reason, the smoothness of the surface of the coating liner to be obtained and the glossiness of the white paper are insufficient, and the printability is deteriorated, for example, print blurring occurs when printing.

  The present applicant discloses a color liner having two coating layers in JP-A No. 2002-285495. The color liner disclosed in the publication has a high glossiness and is free from cracks in the ruled line, but a coating liner that further improves printing gloss and hardly breaks the coating layer is desired.

JP 2002-285495 A

  Accordingly, an object of the present invention is to provide a coating liner having good printing gloss and being hard to break the coating layer.

As a result of intensive studies to achieve the above object, the inventors of the present invention applied a specific paint to the surface of the base paper subjected to the surface smoothing treatment and dried to form a coating layer, which was measured according to JIS-P8142. The present inventors completed the present invention by obtaining the knowledge that a coated liner having a gloss of white paper within a specific range can achieve the above object.
The present invention has been made based on the above knowledge, and is obtained by applying 3 to 8 g / m ^{2 of a} coating containing an inorganic pigment, an organic pigment, and a binder on the surface of the base paper that has been subjected to surface smoothing treatment. The present invention provides a coating liner on which a working layer is formed, wherein the 75 ° white paper gloss measured in accordance with JIS-P8142 is 16% or more.
It is preferable that the paper layer which comprises the said base paper is two or more layers, and the surface layer is a pulp layer containing waste paper or a bleached pulp.
The coating liner preferably has a 10-point average surface roughness (Rz) measured according to JIS-B0601 of 2.0 to 7.0 μm.

  The coating liner of the present invention has good printing gloss and is resistant to cracking of the coating layer. The coated liner of the present invention has a beautiful white paper appearance and printed appearance, and can be suitably used as a cosmetic cardboard liner.

Hereinafter, the coating liner of the present invention will be described.
In the coating liner of the present invention, a coating layer obtained by applying a coating material containing an inorganic pigment, an organic pigment and a binder to the surface of the base paper subjected to the surface smoothing treatment and drying is formed.

As a raw material of the base paper used in the present invention, a raw material usually used as a corrugated board liner can be used without any particular limitation, and those composed of pulp are preferably used.
The base paper used in the present invention may be a single layer or multiple layers. However, it is particularly preferable that the base paper is composed of multiple layers from the viewpoint of increasing the basis weight and ensuring the compressive strength and rigidity required for corrugated cardboard. The base paper used in the present invention is preferably a pulp layer whose surface layer contains waste paper or bleached pulp. Examples of the used paper include colored waste paper and Kent waste paper. The surface layer of the present invention may be a layer containing bleached pulp, or used paper pulp and bleached pulp may be mixed and used.

Moreover, you may mix and use other mechanical pulp etc. for the pulp which comprises a base paper. Moreover, you may add suitably a sizing agent, a paper strength agent, a chemical fixing agent, a filtering agent, a filler, etc. as needed at the raw material preparation process.
In addition, although there is no restriction | limiting in particular in the basic weight of the said base paper, it is preferable from a viewpoint of weight reduction that it is about 100-300 g / m < ² >.

  In addition, as the base paper used in the coating liner of the present invention, one that has been subjected to surface smoothing treatment such as various calendar treatments before the coating of the paint on the base paper is used. In other words, by subjecting the base paper before coating to surface smoothing, the unevenness of the surface of the base paper can be reduced, and the unevenness of the surface of the base paper can be obscured without increasing the coating amount. In particular, printability can be improved. Further, since the coating amount of the paint can be reduced, it is not necessary to apply the paint twice, and only one coating equipment is required, so that the equipment cost can be reduced and the coating liner can be obtained at a low cost. be able to. The apparatus for smoothing the surface of the base paper is not particularly limited, and for example, a machine calendar, a soft calendar, a Yankee dryer or the like is used as appropriate.

Next, the paint applied to the base paper will be described. The paint used in the present invention comprises an inorganic pigment, an organic pigment and a binder.
Examples of inorganic pigments include talc (3MgO · 4SiO ₂ · H ₂ O), clay (including modified clays such as calcined clay and chemically modified clay), heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, Examples thereof include silica, barium sulfate, calcium sulfate, zinc sulfide, satin white, kaolin, and silica (SiO ₂ or SiO ₂ · nH ₂ O). Among these inorganic pigments, in particular, when clay, talc, or calcium carbonate is used, it is possible to maintain better printing quality and to manufacture a coated liner at a low cost.
Examples of organic pigments include polystyrene and polyacrylic resin pigments, urea resin pigment plastic pigments, hollow spherical plastic pigments, and hollow glass pigments. The inorganic pigment and organic pigment may be used alone or in combination of two or more.

  The content of the inorganic pigment in the paint is preferably 60 to 93% by mass, and more preferably 75 to 85% by mass. If the content of the inorganic pigment is less than 60% by mass, the amount of the organic pigment and the binder increases, so the viscosity and concentration of the coating agent become unstable, causing problems such as coating unevenness and further coating. On the other hand, when the amount exceeds 93% by mass, the amount of the binder is reduced, so that the adhesive force between the coating agent and the base paper is reduced, and the picking phenomenon is liable to occur during printing, and the coating layer is cracked. It becomes easy.

  Further, the content of the organic pigment in the paint is preferably 2 to 30% by mass, and more preferably 4 to 10% by mass. When the content of the organic pigment is less than 2% by mass, the roughness of the coated paper surface and the glossiness of the white paper are lowered, so that the printing gloss is also lowered. On the other hand, if it exceeds 30% by mass, the viscosity and concentration of the coating agent become unstable, which causes problems such as coating unevenness.

  Examples of binders include polyvinyl alcohol, casein, polyacrylamide, polystyrene-butadiene latex, polyvinyl acetate latex, polyacrylic latex, polyurethane latex, enzyme-modified starch, cold water soluble starch, phosphate esterified starch, etherification Highly water-dispersible by homopolymerization or copolymerization of starch, starch, such as oxidized starch, proteins such as casein, soy protein, synthetic protein, vinyl monomers such as polyvinylpyrrolidone, carboxymethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, styrene, butadiene Examples include molecular substances. These binders may be used alone or in combination of two or more.

The content of the binder in the paint is preferably 5 to 25% by mass, more preferably 10 to 15% by mass in terms of absolute dry mass. When the binder content is less than 5% by mass, the adhesive force between the coating agent and the base paper is low, and the picking phenomenon is liable to occur during printing, and the coating layer is easily broken. On the other hand, even if it exceeds 25 mass%, the effect of a binder does not improve any more and is not economical.
The paint used for producing the coating liner of the present invention is obtained by dispersing the above-mentioned inorganic pigment, organic pigment and binder in water.

  In addition to the above-mentioned inorganic pigments, organic pigments, and binders, paints include dispersants, pH adjusters such as sodium hydroxide and aqueous ammonia, antifoaming agents, preservatives, fluorescent dyes, mold release agents, and dyes as necessary. Water resistance agents, flow modifiers, color pigments, and the like may be added.

  The coating apparatus for applying the coating material to the base paper is not particularly limited, and examples thereof include an air knife coater, a blade coater, a rod coater, a bar coater and a gate roll coater, a roll coater such as a size press, and a velvapa coater. Used as appropriate.

The coating amount of the coating of the base paper is conventionally less than the amount that is applied to the coating liner was developed to impart beautification of a ^{3g / m 2 ~8g / m 2} , preferably 4g / M ^{2 to} 6 g / m ² . When the coating amount of the paint on the base paper is less than 3 g / m ² , the surface smoothness is lowered, and it becomes difficult to obtain the roughness and glossiness, and the printability is lowered. On the other hand, when it exceeds 8 g / m ² , when the obtained coating liner is folded, the coating layer at the bent portion is easily broken. In addition, the coating amount of a coating material is represented with the mass of solid content.
It is preferable to perform a calendar process after applying the paint on the base paper. When the calendar treatment is performed, the gloss and smoothness of the coated surface are improved, and the ink setting property at the time of printing is improved. Therefore, it can be more suitably used as a cosmetic liner. The calendering process may be performed before or after the coating is dried, or may be performed in two stages before and after drying. In particular, calendering using an elastic roll such as a soft calender or gloss calender is performed after drying. It is preferable because a coated liner with uniform gloss can be obtained.

  As described above, the coating liner of the present invention has a coating layer formed by coating a base paper with a paint and drying, and a protective layer is further formed on the surface of the coating layer. May be provided. The protective layer is provided to protect the coating layer. Specifically, it provides wear resistance and heat resistance at the time of bonding, further increases the gloss of the surface, and prints on the surface. It is for imparting aptitude, water resistance, and box making aptitude. The paint used to form the protective layer contains a resin. Examples of the resin include styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, styrene-acrylic copolymer, and acrylic copolymer. Etc.

The coated liner of the present invention has a 75 ° white paper gloss of 16% or more, preferably 18% or more, measured according to JIS-P8142. In order to make the glossiness of the blank paper within the above range, it can be carried out by applying 3-8 g / m ² of the above-mentioned paint on the surface of the base paper subjected to the surface smoothing treatment. When the blank paper gloss is lower than 16%, the print gloss is not good.

The coated liner of the present invention has a 10-point average surface roughness (Rz) measured according to JIS-B0601 of preferably 2.0 to 7.0 μm, and more preferably 2.5 to 5.5 μm. Even if Rz is less than 2.0 μm, the blank paper gloss and the print gloss are not substantially different from those in the case where RZ is 2.0 μm. Further, it is considered that a surface smoothing treatment facility for making RZ less than 2.0 μm is necessary, and these incidental equipment costs are incurred, which is uneconomical. On the other hand, if it exceeds 7.0 μm, the glossiness of the blank paper and the printing gloss are remarkably lowered.
There is no particular restriction on the method of setting the Rz of the coating liner in the above range. For example, the use of a surface smoothing processing equipment such as a Yankee dryer, soft calender or machine calender before coating, and the soft calender or machine after coating. It is preferable to use surface smoothening equipment such as a calendar.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto. In the following examples,% represents mass% unless otherwise specified.
Example 1
Blend 60% clay, 20% calcium carbonate (more inorganic pigments), 10% plastic pigments (organic pigments), 9% styrene butadiene latex (binder), 1% auxiliary agents such as antifoaming agents and dyes. A paint adjusted to 55% was formulated.
On the other hand, it is composed of 5 layers of paper layers, a front layer, a front layer, a back layer (3 layers), NBKP (freeness 500 ml CSF) and coated waste paper are used at a mixing ratio of 30:70 for the surface layer, Pulp made of old colored paper is used, pulp made of old paper is used for the back layer, base paper is made, and then surface smoothening is performed at a calender linear pressure of 100 kgf / cm. The coating material was applied at 3 g / m ² and dried, and then subjected to surface smoothing with a soft calender at a linear pressure of 80 kgf / cm to prepare a coating liner having a basis weight of 170 g / m ² .

The coated paper sample obtained as described above was evaluated according to the following method. The evaluation results are shown in Tables 1 and 3.
-White paper gloss The 75 degree white paper gloss of the surface of the coating liner was measured based on JIS-P8142.
(2) Print gloss The print gloss after printing of the coating liner was evaluated as follows. That is, the coated liner sample was printed using a KRK universal printing aptitude tester manufactured by Kumagaya Riki Kogyo Co., Ltd., using a standard duck grade ink used in an IGT printing aptitude tester defined in JIS-P8129. The printed coating liner was evaluated in the same manner as (1).
(3) Smoothness The smoothness was measured according to the Beck smoothness test method of JIS-P8119.

(4) 10-point average roughness (Rz)
According to JIS-0601, it measured using the surf test 211 by Mitutoyo Corporation.
(5) Bending test Applying the coated liner to the part that was bent once, twice, three times, five times, six times, eight times, ten times, twelve times with a JIS-P8115MIT fold strength tester. The condition of cracks in the work layer was visually confirmed and evaluated. Evaluation was performed according to the following evaluation criteria. In addition, this test was done about Examples 1-6 and Comparative Examples 2, 3, and 8-14.
Evaluation criteria ○: No cracks could be confirmed.
(Triangle | delta): The crack was able to be confirmed.
X: The coating layer was completely destroyed.

Examples 2-5
The coating amount of the paint was 4 g / m ² (Example 2), 5 g / m ² (Example 3), 6 g / m ² (Example 4), and 8 g / m ² (Example 4). The same operation as in Example 1 was performed to obtain a coating liner. The obtained coated liner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 1
A liner was obtained in the same manner as in Example 1 except that no paint was applied. The obtained liner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 2 to Comparative Example 6
The coating amount of the paint was 2 g / m ² (Comparative Example 2), 10 g / m ² (Comparative Example 3), 12 g / m ² (Comparative Example 4), 14 g / m ² (Comparative Example 5), 16 g / m. ^{2 A} coating liner was obtained in the same manner as in Example 1 except that it was changed to (Comparative Example 6). The obtained coated liner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Comparative Example 7 to Comparative Example 17
A coating liner was obtained in the same manner as in Example 1 except that the surface smoothing treatment of the base paper was not performed and the coating amount of the paint was changed to the amount shown in Table 2. The obtained coated liner was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

As is clear from Tables 1 and 2, when the surface of the base paper was not smoothed before coating, the gloss of the blank paper was not improved at a coating amount of 8 g / m ² or less. The print gloss was also low. Further, it was found that the surface smoothing treatment was performed before the coating of the paint, and the coated one had an improved white paper gloss and an excellent printing gloss.
Further, as apparent from Table 3, in Examples 1 to 5, no cracks could be confirmed up to 5 times of bending. On the other hand, in Comparative Examples 2, 3, 13 and 14, cracks were confirmed by bending three times. Moreover, it turned out that it becomes easy to crack, so that there are many coating amounts of a coating material.
From the above results, the coating liners of Examples 1 to 5 have good printing gloss and are difficult to break the coating layer.

Claims (3)

A coating liner in which a coating layer obtained by applying 3 to 8 g / m ² of a paint containing an inorganic pigment, an organic pigment and a binder on the surface of the base paper subjected to the surface smoothing treatment,
A coating liner having a 75 ° white paper gloss of 16% or more measured according to JIS-P8142. The coating liner of Claim 1 whose paper layer which comprises the said base paper is two or more layers, and the surface layer is a pulp layer containing waste paper or a bleached pulp. The coating liner of Claim 1 or 2 whose 10-point average surface roughness (Rz) measured according to JIS-B0601 is 2.0-7.0 micrometers.