JPH05247891A - Production of matte coated paper for rotary printing - Google Patents

Abstract

PURPOSE:To obtain a method for producing matte coated paper for rotary printing having excellent surface properties, blister, breaking and cracking resistance for both white paper and printed paper. CONSTITUTION:The objective method for producing matte coated paper for rotary printing is to coat base paper with a coating comprising >=30 pts.wt. heavy calcium carbonate having 1-8mum average particle diameter, 0.1-1 pt.wt. one selected from acrylic polymers, carboxymethyl cellulose and polyvinyl alcohol and/or >=2 pts.wt. starch in 100 pts.wt. total amount of pigments so as to provide <=29g/m<2> coating weight based on one surface of the base paper and then treat the surface with roughened rolls.

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 matte coated paper for rotary printing, which has excellent surface properties even after blank printing and after printing, and has excellent blister resistance and folding crack resistance.

[0002]

2. Description of the Related Art Matte coated paper is preferred for its calm feel and is widely used in the fields of single-color printing to multi-color printing. Recently, the demand for rotary printing has been increasing. The method is to coat the base paper with a conventional paint, keep it dry or to keep the gloss of the paper low, and lighten the surface treatment with a metal roll (chilled roll) to commercialize it. It has a drawback that the surface property is inferior even after printing.

Further, in order to compensate for the inferior surface property, when the coating amount is increased, in the case of rotary printing, when the water in the paper tends to evaporate and diffuse due to the hot air for drying the ink, the coating is applied. The paper is swollen because it is blocked by the layers and cannot escape.

Further, as the coating amount of the paint increases, the breakability also deteriorates. Folding cracking resistance is an important requirement along with blister resistance during rotary printing. Folding cracking causes the product to have an extremely low water content due to the hot air used to dry the ink during rotary printing. Occasionally, cracks occur at the folds. Since the coating layer has a lower strength than the base paper layer, the more coating layers, the more likely it is to be adversely affected.

[0005]

That is, it is not possible to obtain a matte coated paper for rotary printing having excellent surface properties that can withstand high-grade applications, and it is attempted to supplement the deterioration of surface properties with a thick coating of paint. Therefore, at present, both the blister resistance and the folding crack resistance are inferior. Therefore, the development of a matte coated paper for rotary printing, which has excellent surface properties, blister resistance, and folding crack resistance, has become an urgent issue.

From the above circumstances, the present inventors have conducted various studies on the coating material to be coated on the base paper and the method of surface treatment after coating. As a result, the composition of the coating material is specified, and after coating on the base paper, If surface treatment is carried out by a new method that replaces the conventional metal roll, the surface properties will be excellent, and therefore the coating amount will be small, so the production of matte coated paper for rotary printing with excellent blister resistance and crease resistance. The present invention has been achieved by finding out what can be done.

[0007]

According to the present invention, the average particle size is 1
~ 8μm of heavy calcium carbonate, 30 parts or more in 100 parts of total pigment, 0.1 to 1 type selected from acrylic polymer, carboxymethyl cellulose, polyvinyl alcohol
Part and / or a coating material containing 2 or more parts of starch is applied to a base paper with a coating material containing 2 parts or more of starch per surface of 29 g / m ² or less, and then the surface is treated with a roughening roll to produce a matte material for rotary printing. It is a method for producing coated paper.

[0008]

The present invention has the above-mentioned constitution, and the surface property can be improved by improving the surface treatment method after coating the base paper with the coating material, and the coating amount of the coating material can be reduced as much as possible. The water-retaining property suppresses the permeation of the paint into the base paper and improves the coating property of the paint, so that the coating amount of the paint can be reduced, and thus the blister resistance and the crease resistance are reduced. It is the gist of the present invention that it can be improved.

First, the surface treatment method after coating the base paper with the coating material will be described. A conventional super calender is equipped with a roughening roll together with an elastic roll, and is applied to a pressure contact nip between the roughening roll and the elastic roll. By passing through the paper, a product with a fine and smooth texture and excellent so-called surface finish is obtained.

At this time, the surface roughness (R _max ) [based on JIS B 0601] of the roughening roll used is preferably 8 to 25 μm. If it is smaller than this, the matting effect is insufficient, and conversely, if it is rough, the pattern on the roll surface is transferred to the coated paper, so that the surface of the product also becomes rough and the effect of corner bending is impaired. The material of the roughening roll is not particularly limited, and may be a roll made of steel or an alloy having a desired roughness on the surface of the roll by a sand blast method, a corrosion method or the like, or a chromium-plated surface thereof.

The elastic roll may be a known one made of cotton, asbestos, wool, plastic or the like.
Regarding the processing temperature (roll surface temperature), it is not particularly necessary to heat, and may be 45 ° C. or lower. The nip pressure of the roll is determined by a combination of the surface roughness of the roughened roll, the surface temperature of the roll, etc., but may be appropriately selected within the range of 100 to 300 Kg / cm.

As described above, after coating the base paper with the coating material and surface-treating it using a roughening roll, excellent surface properties can be imparted to the product, so that the amount of the coating material coated on the base paper is reduced. Therefore, both blister resistance and crease resistance are improved. However, since the blister resistance is insufficient, the composition of the coating must be proper.

That is, since the coating layer is made to have a good air permeability so that the vapor diffusion of the moisture in the paper due to the hot air at the time of rotary printing is not disturbed, the coating material is a coarse heavy calcium carbonate having a good air permeability. It is good to blend. Precipitated calcium carbonate is generally unsuitable for increasing the air permeability of paints because of its fine particle size. Since kaolin has a flat particle shape,
Since it tends to impair the air permeability of the paint, it is better to mix as little as possible except for the amount necessary for adjusting the glossiness of the product.

Heavy calcium carbonate has an average particle size of 1 to 8 μm.
Things are good. If it is smaller than this, it will not be useful for improving the air permeability of the paint, and the product will be glossy and a sufficient matting effect cannot be obtained. On the other hand, if it exceeds 8 μm, it is too coarse and the surface property of the product is impaired, which is not preferable. Further, in order to fully exert the breathing effect and the matting effect of the heavy calcium carbonate, the heavy calcium carbonate must be blended in 30 parts or more out of 100 parts in total of the pigment in the paint.

However, when a large amount of such coarse ground calcium carbonate is blended, the water retention of the paint is low, so that uneven coating is caused by the coater. Particularly, in the case of a blade coater, the streaks of so-called streaks are applied. Since it is easy to form a part that does not have water, starch with a good water retention effect is added to the total of 100
It is recommended to mix at least 2 parts, preferably 4 to 8 parts per part.

[0016] The addition of starch significantly improves the water retention of the paint and makes it difficult for the paint to penetrate into the base paper, so that the coating property of the base paper surface of the paint is improved and the coating amount can be further reduced. , Further improves blister resistance,
Folding crack resistance is also improved.

As described above, since the water retention of the paint is improved by blending the starch with the paint, it is possible to apply a rough paint having a large amount of heavy calcium carbonate at a low coating amount without unevenness, so that it has excellent blister resistance. Also, it is possible to impart resistance to breakage.

Further, in order to improve the water retention of the paint, it is more effective to use a synthetic polymer or a natural polymer such as an acrylic copolymer, carboxymethyl cellulose, polyvinyl alcohol or the like together with starch as a water retention agent. The mixing ratio is appropriately 0.1 to 1 part with respect to 100 parts of the total amount of the pigment of the paint, and if it is smaller than this range, the effect is not remarkable, and if it is too large, the viscosity of the paint increases too much and the coater causes uneven coating. There is a possibility that it will occur.

Thus, the coating amount of the coating should be suppressed to 29 g / m ² or less on one side, preferably 24 g / m ² or less, and if the coating amount is higher than this, the blister resistance and crease resistance are insufficient. Is. Whether the coating is single-layer coating or multi-layer coating, the total coating amount should not exceed the above range. The drying conditions in the coater are not particularly limited, but the product water content is 5 to 7%.
It is desirable to adjust so that

There is no problem in the papermaking conditions for the base paper as long as the base paper is not particularly weak as long as the above requirements are satisfied, but the higher the strength of the base paper, the more blister resistance and crease resistance there is. That is, the more the base paper is beaten into pulp (preferably 430 ml or less in Canadian Standard Freeness), the more softwood pulp, the lower the ash content (preferably 10% or less), the more neutral paper is stronger than acidic paper. However, if too much softwood pulp is used, the uniformity of the paper, so-called texture, will be impaired, and the coating property of the paint on the surface of the base paper when applying the paint will deteriorate, and the coating amount will have to be increased. Therefore, it is not preferable for the blister resistance and the breakage resistance. It is preferable to apply starch, polyvinyl alcohol, synthetic sizing agent and the like to a base paper of about 2 g / m ² with a size press or gate roll, because the strength is further increased.

[0021]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is of course not limited thereto. The following parts and% are all parts by weight and% by weight.
Indicates.

Example 1 As a pigment, kaolin [manufactured by Engelhard Minerals and Chemicals (EMC, USA), trade name: HT Kaolin] 25 parts, heavy calcium carbonate having an average particle size of 2.0 μm (house-made, ground calcium carbonate) 65 Part and Sachin White (manufactured by In-house) in a mixer, 3 parts of oxidized starch (manufactured by Oji Constarch, trade name, Oji Ace A) and latex (manufactured by Asahi Kasei Co., trade name L-1537) while stirring in the mixer. )
12 parts, moreover polysodium acrylate as a dispersant per pigment
0.3%, 0.5 parts of calcium stearate as a lubricant, 0.2 parts of fluorescent dye are sequentially added, and after thoroughly mixed and dispersed, 25%
A coating solution was prepared by adjusting the pH to be alkaline with an aqueous ammonia solution.

80 parts of hardwood bleached kraft pulp with a beating degree (Canadian standard freeness) of 400 ml and 20 parts of softwood bleached kraft pulp with a beating degree of 400 ml, 0.5 part of cationic starch, 0.3 part of sulfuric acid band, alkenylsuccinic anhydride size 0.12 parts of an agent, 15 parts of heavy calcium carbonate, and 0.02 parts of a cationic retention aid (trade name Percoll-57 manufactured by Allied Colloid Co., Ltd.) are sequentially added to produce paper by a known paper machine, and an enzyme-modified starch is size-pressed. 2g / m ^{2 was} applied to both sides of the base paper having a basis weight of 80g / m ² with the above coating liquid applied on one side with a 20g / m ² blade coater, and dried with a known dryer to obtain paper moisture.
A 6% coated paper was produced.

As shown in FIG. 1, this coated paper S is JIS B
The surface roughness R _max defined by 0601 is 10 μm and the nip pressure is 200 Kg / in a 10-stage super calender 4 in which two hard surface-roughening rolls 1 having elastic roughness 2 and metal roll 3 having a surface roughness R _max of 15 μm A matte coated paper was produced by passing the paper through with the back side (wire side of the paper machine) facing up at a speed of 700 m / min.

Example 2 A coating composition comprising 32 parts of heavy calcium carbonate having an average particle size of 5.2 μm, 58 parts of kaolin, 10 parts of satin white, 4 parts of oxidized starch and 12 parts of latex was used, and the coating amount was applied to one side. The procedure was the same as in Example 1 except that the amount was 28 g / m ² .

Example 3 50 parts of the same heavy calcium carbonate and kaolin 50 as in Example 1
Parts, oxidized starch 2 parts, acrylic copolymer (BASF Corporation, trade name Acrosol C-50L) 0.8 parts, latex 12 parts, except that the coating amount per side is 9 g / m ² Was carried out in the same manner as in Example 1.

Example 4 A coating material having an average particle diameter of 7.3 μm, 40 parts of ground calcium carbonate, 60 parts of kaolin, 5 parts of oxidized starch, 0.1 part of acrylic copolymer, and 12 parts of latex was used. 15g / per side
The procedure was the same as in Example 1 except that m ² was used.

Example 5 85 parts of ground calcium carbonate having an average particle diameter of 3.0 μm, 10 parts of kaolin, 5 parts of satin white, 8 parts of oxidized starch, latex
The same procedure as in Example 1 was carried out except that the paint of 12 parts was used.

Example 6 As in Example 1 except that the coating composition had the same composition as in Example 1 except that 2 parts of oxidized starch and 0.3 part of carboxymethyl cellulose were used and the coating amount was 24 g / m ² per side. It carried out in the same way. Example 7 The same procedure as in Example 6 was carried out except that 0.5 part of polyvinyl alcohol was used together with oxidized starch as a water retention agent for the paint.

Comparative Example 1 A matte coated paper was produced in the same manner as in Example 2 except that the coated amount was 31 g / m ² per side. Comparative Example 2 The heavy calcium carbonate compounded in the paint has an average particle size of 0.8 μm.
Was the same as in Example 4, except that the coating amount was 24 g / m ² per side and the same procedure as in Example 1 was performed.

Comparative Example 3 Example 1 was repeated except that the same paint as in Example 3 was used except that 1 part of oxidized starch and 0.2 part of acrylic copolymer were used, and the coating amount was 20 g / m ² per side. I went in the same way as. Comparative Example 4 Example 1 except that 1.2 parts of the acrylic copolymer was added to the paint.
I went in the same way as.

Comparative Example 5 As in Example 1 except that the coated paper S was surface-treated by passing through the pressure nip of a 10-stage super calender 5 in which the elastic roll 2 and the metal roll 3 shown in FIG. 2 were combined. I went the same way. However, in this case, the pressure of the roll of the super calender was not applied, and the nip pressure was set only by the weight of the roll itself.

Comparative Example 6 Except that 27 parts of heavy calcium carbonate and 63 parts of kaolin were used,
The same paint as in Example 2 was used, and the coating amount was 16 g / m ² per side.
The procedure was the same as in Example 1 except that Comparative Example 7 The same procedure as in Example 4 was carried out except that heavy calcium carbonate having an average particle size of 9.0 μm was compounded in the coating material.

The results obtained in Examples 1 to 5 are shown in Table 1.
Table 2 shows the results obtained in Comparative Examples 1 to 7.

The method for measuring the particle size of the heavy calcium carbonate compounded in the paint, the method for evaluating the occurrence of streaks in the coater, and the method for evaluating the quality of the produced matte coated paper are shown below.

Particle size measuring method of heavy calcium carbonate Light transmission type particle size distribution measuring instrument (manufactured by Shimadzu Corporation, trade name SACP-3
The average particle size is the particle size at which the cumulative weight from the smaller particles to the larger particles reaches 50%, that is, the average particle size.

Evaluation Method of Streak Generation with Coater During coating of the base paper with a coater, the coated surface from immediately after coating with a blade to immediately before drying is visually evaluated, and the best streak-free ones are in order of ○, □, and △. , × is displayed.
In addition, □□, □ Δ, and Δx indicate the middle of both.

Next, a quality evaluation method will be described. Quality evaluation method 1) White paper glossiness: Measured at an angle of 75 degrees in accordance with JIS P 8142. 2) White paper surface property: Matte-coated paper was visually evaluated, and the highest quality was indicated by ○, □, △, ×. In addition, ○
□, □ △, and Δx indicate the middle of the two. 3) Surface property after printing: Matte coated paper was printed by a Mitsubishi diamond printing machine (manufactured by Mitsubishi Heavy Industries, Ltd.), and visually indicated by ○, □, △, × in order from the best one. In addition, ○ □, □ △, △ ×
Indicates an intermediate point between the two.

4) Blister resistance: Matte coated paper at a temperature of 20
After standing overnight at ℃ and 65% relative humidity, it was immersed in an oil bath at 180 ℃ for 3 seconds. The oil that had adhered was wiped off, and the appearance of blisters on the sample was visually evaluated, and the best one without blisters was indicated by ○, □, △, ×. In addition, ○ □,
□ △ and △ × show the middle of both.

5) Fracture resistance: A total of 0.5 cc of black ink (manufactured by Toyo Ink Mfg. Co., Ltd., trade name NT-3) was applied uniformly over the entire width of the ink roll using an RI printer (manufactured by Ming Seisakusho). After that, the roll was rotated and kneaded for 1 minute, and then the ink of the ink roll was transferred (printed) to the sample while rotating the preset sample at 60 rpm.

After the printed sample was placed under a relative humidity of 45% for 24 hours, a folding machine (Omura Tekko Co., Ltd., high-speed paper folding machine) was used to make a crease, and the degree of cracking was visually evaluated. .. The best ones are shown in order from ○, □, △, ×.
In addition, □□, □ Δ, and Δx indicate the middle of both.

[0042]

[Table 1]

[0043]

[Table 2]

As is clear from Table 1, Examples 1, 2 and
In both No. 5 and No. 5, the particle size and blending ratio of the heavy calcium carbonate used for preparing the paint, the blending ratio of starch, and the coating amount of the paint were appropriate, and the coated paper was surface-treated with a roughening roll. The erased surface has a smooth texture and is excellent in both blister resistance and crease resistance. There were few streaks in the coater, and the operation was smooth.

Further, in Examples 3 and 4, the coating material was mixed with starch and an acrylic copolymer, Example 6 was mixed with carboxymethyl cellulose, and Example 7 was mixed with polyvinyl alcohol. Since the amount of coating and the surface treatment of the coated paper were proper, the quality of the product was excellent as in Example 1.

On the other hand, as is clear from Table 2, Comparative Example 1 was inferior in both blister resistance and breakage resistance because the coating amount of the coating material was too large. Since the particle size of calcium carbonate was too small and the blending ratio of heavy calcium carbonate was too low in Comparative Example 6, the blister resistance was poor.

Further, in Comparative Example 3, since the addition rate of starch in the paint was too small and the water retention of the paint was insufficient, streaks were generated in the coater, and streaks were observed in the product.
The evaluation of surface property was dropped. In Comparative Example 4, the amount of the acrylic copolymer added to the paint as a water retention agent was too much, and thus the viscosity of the paint was too high, and streaks occurred in the coater.

In Comparative Example 5, the coating composition and coating amount were proper, but since chilled roll was used for the surface treatment of the coated paper, a mottle pattern was recognized on the surface of the product and it was used for high-grade applications. Was unsuitable. In Comparative Example 7, the surface quality of the product was poor because the heavy calcium carbonate blended in the paint was too coarse.

[0049]

As described above, according to the present invention, it is possible to produce a matte coated paper for rotary printing having a matte surface having excellent surface properties, excellent blister resistance and folding crack resistance, and at a high speed. It is possible to obtain a matte coated paper which is resistant to printing and suitable for the highest grade applications.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a super calendar having a roughening roll.

FIG. 2 is an explanatory diagram of a super calendar having a metal roll and an elastic roll.

[Explanation of symbols]

 1: Roughening roll 2: Elastic roll 3: Metal roll 4, 5: Super calendar S: Coated paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B05D 7/24 E 8720-4D (72) Inventor Kusumi Koji 373 Yoshioka, Yonago, Tottori Prefecture Oji Paper Co., Ltd. Stock company Yonago factory

Claims (1)

[Claims] 1. A heavy calcium carbonate having an average particle size of 1 to 8 μm, 30 parts or more per 100 parts of a pigment, an acrylic polymer,
A coating containing 0.1 to 1 part of one selected from carboxymethyl cellulose and polyvinyl alcohol and / or 2 parts or more of starch per one side of the base paper is coated at 29 g / m ² or less, and then surface-treated with a roughening roll. A method for producing a matte coated paper for rotary printing, which comprises: