JPH09228298A - Production of gloss coated paper and gloss coated paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide gloss coated paper which is bulky, reduced in fine gloss unevenness and can give surface smoothness, printability with reduced coating weight, thus having high cost competitiveness. SOLUTION: When the substrate paper is coated with a pigment coating liquid and gloss-finished, the high-temperature soft calendering is combined with the brushing calendering using a brush composed of a bristles-planted brushing roll and a metal roll.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a glossy coating having high bulkiness, excellent surface condition (fine gloss unevenness), surface property, printability and high productivity when a base paper is coated with a pigment coating liquid. The present invention relates to a method of manufacturing a paper and a glossy coated paper.

[0002]

2. Description of the Related Art In recent years, the demand for printing paper has been gradually increasing. In particular, the demand for commercial printing for advertising and promotion of leaflets, catalogs, pamphlets, direct mails, etc. is growing significantly. These commercial prints have low commercial value themselves, but since it is important that the purpose is achieved as an advertising medium, it is required to have good print finish at low cost. Further, the user's tendency toward cost reduction has been further strengthened, and the papers used have been toward lower coating weight and lower grade, for example, from art paper to coated paper or from coated paper to lightweight coated paper.

[0003] In order to respond to such a vigorous demand for coated paper, it is an important technical problem for paper manufacturers to increase productivity and reduce costs while maintaining high quality.

Generally, one of the means for reducing the cost in the manufacturing prescription is to lower the coating amount as described above, but if the coating amount is reduced, the surface properties such as the glossiness and smoothness of white paper and the printability are deteriorated. Is inevitable. As another means, it is conceivable to mix more inexpensive calcium carbonate in a large amount for the pigment coating liquid, but if it is mixed in a certain amount or more, it becomes difficult to obtain white paper gloss and smoothness due to poor pigment orientation. The problem arises.

Also, an attempt to adopt a multi-layer coating system has been made for the purpose of improving the coverage of the base paper and simultaneously reducing the cost and improving the quality by applying an on-machine coating with an undercoat pigment coating liquid containing an inexpensive pigment. Has been done. However, the quality of the multi-layer coated paper manufactured by the on-machine method is better than that of the single-layer coated paper because the basis weight of the base paper is reduced and the total coating amount of the undercoat and the topcoat is considerably increased. However, the cost is not necessarily reduced by the multilayer coating under the present circumstances.

In addition to this, as a means for improving the productivity on the apparatus, there is a soft calender treatment at high temperature (Japanese Patent Laid-Open No. 54-125712). This is a conventional method in which a coated paper coated with a pigment by various coating devices (hereinafter referred to as a coater) is once wound up, and then a super calender is used at a low temperature (50 to 70 ° C.) and usually 10 to 14 Productivity is achieved by using a high-temperature soft calender instead of the super calender, which is processed online under a multi-stage nip condition to give gloss, and is then directly processed by calendering online. It is intended to dramatically increase In the conventional method, since the elastic roll of the super calender is a cotton roll, heat resistance, pressure resistance, and durability are poor due to the problem of internal heat generation, and there is a limit to speeding up, and the maximum operating speed is about 800 m / min. is there. Therefore, two super calenders are required to be used in combination with a coater of more than 1000 m / min in recent years, which is a problem in terms of labor saving and space saving. On the other hand, in the case of a soft calender that has an elastic roll of plastic with excellent heat resistance and pressure resistance, 1000 m online
It is also possible to operate at a high speed of over a minute. Further, since high-temperature processing is possible, it is not necessary to perform multi-step nip processing, and it is possible to save space by processing with a smaller number of nips. Also, in terms of quality, since the mirror surface of the metal roll is transferred to the surface of the coated paper in a state where only the surface layer of the coated paper is plasticized by the high temperature, it is bulky (low density), strong, and has a glossiness of white paper. Surface properties such as smoothness and printability are also improved.

However, when the coated paper is subjected to a soft calendar treatment at a high temperature, unevenness of the basis weight of the base paper, unevenness of the coating amount, and the like appear as minute gloss unevenness, which causes a problem of impairing the appearance of the coated paper. there were. On the other hand, JP-A-4-37029
Japanese Patent Laid-Open No. 8 discloses that trapping unevenness, which is considered to be caused by gloss unevenness, is improved by applying steam humidification before the high temperature soft calender treatment. However, the inventors of the present invention could not sufficiently improve the minute gloss unevenness as the temperature became higher in the soft calender treatment.

[0008] As described above, the paper manufacturer makes an effort to further reduce the cost and improve the productivity while maintaining the quality by reducing the coating amount by the layer and performing the soft calendering treatment at a high temperature. At present, it is difficult to achieve both quality and productivity.

[0009]

In view of the above situation, the present invention has a problem with a high temperature soft calender for imparting gloss to a pigment coated paper in the above high temperature soft calender treatment of 130 ° C. or more. Another object of the present invention is to provide a method for producing a glossy coated paper which is excellent in surface property and printability with a smaller coating amount, and the glossy coated paper.

[0010]

Means for Solving the Problems The inventors of the present invention have made extensive studies as to the above-mentioned problems, and as a result, in a finishing method of applying a pigment coating liquid to a base paper and glossing the base paper,
The present invention was accomplished by calendering at a high temperature of 30 ° C. or higher using a brushing calender composed of a brush roll and a metal roll in which fibers were planted immediately before or immediately after the soft calender treatment.

As a result, it was possible to greatly improve the minute gloss unevenness which was observed when the conventional high temperature soft calender was used alone. It is considered that the slight gloss unevenness is caused by unevenness of the basis weight of the base paper, uneven coating amount, unevenness of pigment orientation, etc. on the surface of the coated paper. It is considered that the brush fibers act on the recesses as well, and the surface properties of the minute regions are made uniform to improve the properties.

Further, by using the brushing calendering process in combination with the high temperature soft calendering process, in addition to the improvement of the fine gloss unevenness described above, the coating amount is smaller and the bulkiness is higher as compared with the conventional product which is treated with the super calender alone at a lower temperature. It was confirmed that high white paper glossiness, smoothness, and printability were obtained.

The position of the brushing calendar is
The effect was the same immediately before and after the soft calendar. However, brushing calendar alone is a device that rubs and polishes the surface, unlike the conventional calender method in which strong pressure is applied to the paper to crush the entire paper layer and surface to reduce irregularities and give gloss. Did not improve much.

Regarding the soft calendering temperature, when used in combination with a brushing calender, the surface property and printability were good at 130 ° C. or higher, and particularly when it exceeded 150 ° C., a more remarkable effect appeared. Further, when the soft calendering temperature was lower than 130 ° C., the improvement in surface property and printability was insufficient even when used in combination with a brushing calender.

Further, as for the pigment coating liquid, by coating the pigment coating liquid containing calcium carbonate in an amount of 65% by weight or more based on all pigments, it is possible to further reduce the fine gloss unevenness after the calendar treatment. It was This is considered to be because the pigment orientation unevenness is reduced by adding a large amount of calcium carbonate.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION As the calcium carbonate used in the present invention, heavy calcium carbonate and light calcium carbonate are appropriately used. Other pigments used are kaolin, clay, talc, satin white, which are generally used for papermaking, Plastic pigment, titanium dioxide, etc. are used.

As the adhesive used in the pigment coating liquid, various copolymer emulsions of styrene / butadiene type, styrene / acrylic type, ethylene / vinyl acetate type, etc. and polyvinyl alcohol, maleic anhydride copolymer, etc. are synthesized. A system adhesive, oxidized starch, esterified starch, enzyme-modified starch, etherified starch and cold water-soluble starch obtained by flash-drying them are used.

The pigment coating liquid of the present invention contains a dispersant, a thickener,
You may use various auxiliary agents mix | blended with the pigment for normal coated papers, such as a water retention agent, a defoaming agent, and a waterproofing agent. Further, as the base paper, a high-quality paper having a basis weight of 30 to 200 g / m ² or a medium-quality paper used for a general coated paper for printing is selected and used according to the purpose.

The pigment coating liquid may be applied to the base paper by a single-layer coating or a multi-layer coating, and a generally used apparatus can be used as the coating apparatus, but in the case of the single-layer coating, the fountain is mainly used. A blade or roll application blade method is adopted. In the case of multi-layer coating, a film transfer system such as a gate roll coater, a blade or a rod metalling size press coater, a fountain blade system or an air knife system is mainly used for the undercoat coating. A blade method is generally adopted for the top coating as in the case of the above single layer coating.

The coating amount of the pigment coating liquid is preferably 8 to ²⁰ g / m ² in terms of solid content on one side of the base paper.

The type of the soft calender used in the present invention is preferably two to four tandem rolls and two to four stacks in consideration of ease of paper passing and space saving. The tandem type is a soft calender of a type in which two rolls in which a pair of metal rolls and elastic rolls are stacked are arranged in parallel. Further, the material of the elastic roll is not particularly limited, but a modified urethane type excellent in heat resistance, an epoxy type,
It is preferably made of a plastic such as polyether. Further, it is desirable to use a Shore hardness D87 to 94 having good heat resistance, pressure resistance and durability.

For the brush roll of the brushing calendar, synthetic fibers such as nylon, polyester, acryl, polyurethane, and aramid are used, and the hardness, density, elastic modulus and other characteristics are appropriately changed and used. The fiber length to be planted in the roll is mainly 40 to 60 mm, and the roll diameter is about 200 to 800 mm. The number of brush rolls is usually 2 to 12, and like the soft calender, two to three stacks of tandem type rolls are preferable from the viewpoint of easy paper passage. The rotation direction of each brush roll may be forward rotation or reverse rotation with respect to the paper running direction. The rotation speed is preferably 10 to 30 times the speed of a normal coater. When it is less than 10 times, the effect of polishing the surface of the coated paper is reduced, and the improvement of the surface property and the reduction of minute gloss unevenness are likely to be insufficient. Further, even if the speed is increased more than 30 times, there is no difference in the effect, so that it is not necessary.

[0023]

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

<Quality Evaluation Method> (1) Calcium Carbonate Average Particle Size: The 50% point of the weight cumulative distribution was measured as the average particle size using a Seishin Enterprise optical transmission type particle size distribution measuring device SHC5OOO. (2) Fine gloss unevenness: The final product was visually evaluated in the following four stages. ⊚: None, ◯: Almost none, Δ: Slightly present, ×: Very uneven glossiness (3) White paper glossiness: Angle 7 according to J1S P-8142
Measured at 5 degrees. (4) Smoothness: According to JAPAN Tapi No5,
It was measured with an Oken type smoothness tester. (5) Gloss after printing: RI-II type printing machine (manufactured by Ming Seisakusho)
Was printed using 0.35 cc of ink for offset printing (trade name: Diatone GSL Red) manufactured by Sakata Inks, and the glossiness was measured at 75 degrees after standing for 24 hours.

[Example 1] 70 parts of ground calcium carbonate (Shiroishi Calcium Co., Ltd., Hydrocarbo 90) having an average particle size of 0.60 µm and kaolin (ECC Co., Ltd., β having an average particle size of 0.55 µm) Coat) To 100 parts of a pigment containing 30 parts, 0.3 part of a sodium polyacrylate-based dispersant is added and dispersed in water using a Cowles disperser, and 4 parts of phosphate esterified starch is used as an adhesive. And 10 parts of styrene / butadiene copolymer latex were mixed to prepare a pigment coating liquid having a concentration of 66%.

Base paper having a basis weight of 60 g / m ² (Canada standard type bleached hardwood kraft pulp having a freeness of 300 ml alone)
In addition, using a fountain blade coater as a coating device, the coating speed was 1000 m / min, and the solid content was 1 per side.
After coating 3g / m ² on both sides and drying, 2 rolls ・ 2
Soft calender of stack, temperature 160 ℃, linear pressure 20
It was calendered under the condition of 0 kg / cm. Next, polyurethane fiber with a fiber length of 50 mm and a roll diameter of 5
The surface was treated with a 2-roll / 2-stack brushing calendar consisting of a 00 mm brush roll and a metal roll.

Example 2 Heavy calcium carbonate having an average particle size of 0.90 μm (Sankyo Seiko Co., Ltd., Escalon # 2)
200) and the average particle size is 0. A coated paper was produced in the same manner as in Example 1 except that 25 parts of 55 μm kaolin (ECC Co., Ltd., β-coat) was used.

[Example 3] A coated paper was produced in the same manner as in Example 1 except that the brushing calendering was performed immediately before the soft calendering.

[Example 4] 55 parts of heavy calcium carbonate having an average particle size of 0.60 µm (Shiroishi Calcium Co., Ltd., Hydrocarb 90) and kaolin having an average particle size of 0.55 µm (ECC Co., β-coat) ) A coated paper was produced in the same manner as in Example 1 except that 45 parts were used.

[Comparative Example 1] 55 parts of heavy calcium carbonate having an average particle size of 0.60 μm (Shiroishi Calcium Co., Ltd., Hydrocarbo 90) and kaolin having an average particle size of 0.55 μm (ECC Co., β A coated paper was produced in the same manner as in Example 1 except that 45 parts of (coat) was used and no brushing calendar was used.

Comparative Example 2 55 parts of heavy calcium carbonate (Shiroishi Calcium Co., Ltd., Hydrocarbo 90) having an average particle size of 0.60 μm and kaolin (ECC Co., Ltd., β having an average particle size of 0.55 μm). Coat) 45 parts, 1
A coated paper was produced in the same manner as in Example 1 except that the soft calendar treatment was carried out at 00 ° C.

Comparative Example 3 55 parts of heavy calcium carbonate having an average particle diameter of 0.60 μm (Hydro Calcium Co., Ltd., Hydrocarbo 90) and kaolin having an average particle diameter of 0.55 μm (ECC Co., β A coated paper was produced in the same manner as in Example 1 except that 45 parts of (coat) was used and a soft calendar treatment was performed at 60 ° C. without using a brushing calendar.

[Comparative Example 4] Pigment coating solution was coated on both sides in a solid content of 15 g / m ^{2 on} both sides, dried, and then wound up once, and then using a conventional 12-stage super calender.
A coated paper was produced in the same manner as in Example 1 except that the treatment was carried out at 0 ° C. and the brushing calendar treatment was not carried out.

The above results are shown in Table 1.

[0035]

[Table 1]

As is clear from Table 1, Examples 1, 2 and
3 and 4 are bulky (low density) and have little uneven glossiness,
It also has excellent white paper gloss, smoothness, and gloss after printing.

On the other hand, Comparative Example 1 has many fine gloss unevenness. Comparative Example 2 is inferior in smoothness. Comparative Example 3 is inferior in white paper glossiness, smoothness, and gloss after printing. Comparative Example 4 is a conventional manufacturing method, but has a high density and is not bulky.

Therefore, the glossy coated paper produced according to the present invention gives an unprecedentedly excellent coated paper quality, and its effect is extremely great.

[0039]

EFFECTS OF THE INVENTION In the finishing step of applying gloss after applying the pigment coating liquid, fine gloss unevenness, which is a problem during high temperature soft calendering, is improved, and even smaller coating amount improves surface properties and printability. An excellent gloss coated paper can be obtained.

Claims (3)

[Claims] 1. A method for producing a gloss-coated paper, which comprises applying a pigment-coating liquid to a base paper and applying gloss to the dried pigment-coated paper by high-temperature soft calender treatment to obtain 13 pigment-coated papers.
A method for producing a glossy coated paper, which comprises performing a calendering treatment at a high temperature of 0 ° C. or more at a high temperature of 0 ° C. or more immediately before or after the soft calendering treatment using a brushing calender composed of a brush roll and a metal roll having fibers planted therein. 2. The method for producing gloss-coated paper according to claim 1, wherein a pigment coating liquid containing 65% by weight or more of calcium carbonate based on all pigments is used. 3. A glossy coated paper manufactured by the manufacturing method according to claim 1.