JPH0797792A - Method for producing double-sided cast coated paper - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for producing a double-sided cast coated paper, which is particularly excellent in quality, and a lightweight double-sided cast coated paper. A method for producing a double-sided cast coated paper, comprising: providing a cast coating layer containing a pigment and an adhesive as a main component on a base paper, and finishing the wet coating layer by pressing against a mirror surface drum. In particular, the base paper has a basis weight of 45 g / m ² or less, the double-sided cast coated paper (product) has a basis weight of 65 g / m ² or less, and a diameter of 0.05 m that penetrates the base paper layer of the base paper.
A method for producing a double-sided cast coated paper using a base paper in which the number of pinholes of m or more is 100/100 cm ² or less.

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 double-sided cast coated paper, and more particularly to a method for producing a lightweight double-sided cast coated paper.

[0002]

2. Description of the Related Art Wet casting method, rewet casting method, gelling casting method and the like are known as methods for producing strong glossy paper for printing called cast coated paper. In all of these methods, while the cast coating layer containing pigments and adhesives as the main components is in a wet state, it is pressed against the surface of the mirror surface drum that is heated, dried, and released from the surface of the heating drum to give a strong gloss finish. It is common to do.

The cast coated paper thus obtained is
Compared with general coated paper such as super calendered art paper and coated paper, it has very good white paper gloss and surface smoothness, and it also has excellent printing effects, so It is used exclusively for various purposes such as paper containers.

In recent years, as printed materials have become more sophisticated and have become more colored, there has been an increasing demand for coated papers having excellent printing effects, particularly lightweight coated papers for high-grade printing as text sheets for books and magazines. . On the other hand, even in cast coated paper, there is a demand for weight reduction while maintaining the quality such as its excellent white paper appearance and printing effect. In particular, it is possible to reduce the weight of so-called double-sided cast coated paper that is cast finished on both sides. Is requested.

In the conventional casting finishing method, the coating amount of the coating layer provided on the base paper is generally 20 to 40 per side.
g / m ² is necessary, and when the coating amount per one surface is 20 g / m ² or less, gloss reduction, pinholes, gloss unevenness, etc. on the surface of the cast coated paper obtained are likely to occur. Therefore, it has been very difficult to reduce the weight of cast coated paper. Double-sided cast coated paper, especially 100 g / m ²
In order to obtain the following lightweight double-sided cast coated paper, it is necessary to reduce the coating amount of the cast coated layer, and since the ratio of the base paper rice tsubo to the entire double-sided cast coated paper becomes low, pinholes, uneven gloss, etc. It is difficult to produce lightweight double-sided cast coated paper because of problems in quality, moreover, problems in operation such as occurrence of drum picks and wrinkles, or paper breakage tend to occur.

Various proposals have been made to solve the above problems. For example, Japanese Patent Laid-Open No. 63-2111394
No. 10 to 80% by weight of a pigment having an oil absorption of 50 ml / 100 g or more in the undercoating layer, and the air permeability of the support provided with the undercoating layer is 300 seconds or less. It has been proposed that the coat weight of the layers can be reduced. Although it is possible to reduce the weight of the cast coating layer by this method, it is feared that the surface strength of the surface of the cast coating layer will be reduced when the proposed undercoat coating layer is used.

On the other hand, in JP-A-2-221488, a protein-based adhesive is used for the undercoat layer and Zn, Al
Alternatively, there is also a proposal that a lightweight double-sided cast coated paper can be efficiently produced by including at least one selected from the group consisting of Mg metal salt, zirconium salt, epoxy compound, glyoxal and / or amino resin. Further, Japanese Patent Laid-Open No. 4-300388 proposes that a light weight double-sided cast coated paper can be efficiently produced by using a specific base paper produced by a paper machine equipped with a double-sided dehydration mechanism. Furthermore, in Japanese Patent Laid-Open No. 4-308298,
As a pigment for the cast coating layer, the single particle size is 0.05 to
A method has been proposed in which a lightweight double-sided cast paper can be efficiently produced by using 0.15 μm cubic calcium carbonate and specifying the air permeability after one-sided casting.

[0008] By these methods, the weight of rice is 65-90.
Although the production of lightweight sided cast coated paper g / m ² is possible, to obtain a double-sided cast coated paper ultralight such 65 g / m ² or less, must be solved in terms of quality and operation surface various There are drawbacks. That is, in order to obtain a double-sided cast coated paper of 65 g / m ² or less, 40 to 45
A base paper of g / m ² or less must be used as a support. When such a lightweight base paper is used, many pinholes that penetrate the base paper layer are present, and as a result, the casting coating liquid passes through the pinholes when the double-sided eye is cast and finished. There is concern that there may be problems in operation such as the induction of drum picks and drum blisters due to uneven penetration on the surface of the cast coating layer on the back surface as a result, and the dry state of the pinhole portion being slower than the surrounding area. To be done. As described above, it is extremely difficult under the conventional method to stably produce an ultralight double-sided cast coated paper of 65 g / m ² or less.

[0009]

From the actual situation as described above,
The present inventors have earnestly conducted research on a method capable of stably producing a super-lightweight double-sided cast coated paper of 65 g / m ² or less with high quality. As a result, by using a specific base paper, more preferably, a specific basecoat base paper having a basecoat coating layer provided on the base paper, a high-quality ultralight double-sided cast coated paper desired by the present invention is stable. I found a method that can be obtained.

[0010]

DISCLOSURE OF THE INVENTION According to the present invention, a casting coating layer containing a pigment and an adhesive as a main component is provided on a base paper, and the casting coating layer in a wet state is pressed against a mirror-finished drum for finishing. In the method for producing cast coated paper, the base paper has a basis weight of 45 g / m ² or less and a double-sided cast coated paper (product)
The double-sided cast is characterized in that the base paper has a weight of 65 g / m ² or less and the number of pinholes having a diameter of 0.05 mm or more penetrating the base paper layer of the base paper is 100/100 cm ² or less. It is a method for producing coated paper.

[0011]

The inventors of the present invention have made earnest studies on how to prepare a base paper for light-weight double-sided cast coated paper, and found that the number of pinholes having a diameter of 0.05 mm or more penetrating the base paper layer is light-weight double-sided cast. It has been found that the quality and operability of paper are greatly affected, and pinholes in the base paper are identified, and more preferably, by using a base paper provided with an undercoat coating layer on the base paper, high-quality lightweight double-sided cast coating The present invention has been completed by finding a method for stably obtaining a coated paper.

That is, according to the present invention, the basis weight of the base paper is 45 g / m ^2.
The following is an important feature in using a base paper in which the number of pinholes having a diameter of 0.05 mm or more penetrating the base paper layer of the base paper is 100 pieces / 100 cm ² or less. The diameter of the pinhole that penetrates the base paper layer is 0.05 mm
In the above cases, the coating liquid for casting is likely to permeate to the back surface through this pinhole, especially abnormal quality such as uneven penetration on the back surface (previous cast surface) that occurs during the casting finish on both sides, and further drum picking. Operation problems such as drums and blister are likely to occur. Further, when the diameter of the pinhole penetrating the base paper layer is less than 0.05 mm, due to the size effect of the base paper, the coating liquid for casting hardly penetrates into the pinhole, resulting in uneven penetration and drum picking, Drum blister quality and operational problems are unlikely to occur.

In the present invention, the pinholes having a diameter of 0.05 mm or more penetrating the base paper layer itself have a bad influence on the quality and operability, but the number thereof is particularly important. 100/100 cm ² or less, preferably to be 75/100 cm ² or less, more preferably 50/100 cm ² or less it is weight requirements. By the way, when the number of pinholes having a diameter of 0.05 mm or more exceeds 100/100 cm ² , quality such as permeation unevenness, drum pick, drum blistering, etc., and abnormal operation are likely to occur, and the desired effect of the present invention is obtained. Hard to get.

Therefore, in the present invention, the desired double-sided cast coated paper can be obtained very efficiently by specifying the pinholes of the base paper as described above. And. The method for suppressing pinholes in the base paper in this case is not particularly limited, but a particularly effective method is to strengthen the beating of pulp, particularly NKP, and for example, Canadian standard freeness (JIS-P- 8121) is 500 ml or less, preferably 400 ml or less, more preferably 300
It is preferably adjusted to be less than or equal to ml. Further, the ash content of the base paper is adjusted to 7% by weight or less, preferably 5.5% by weight or less, and the amount of the internally added sizing agent is 0.7% by weight or more, preferably to increase the sizing degree of the base paper. Is 1.0
It is desirable to adjust the content to be not less than weight%. On the mechanical side, the deaerator is strengthened to remove air bubbles in the stock, and the landing point of the slice jet and the placement of the dewatering device on the wire part are adjusted to balance the initial dewatering and other raw paper quality. It is done by fine adjustment.

The pulp used when the base paper of the present invention is made into paper. What is used in a general paper machine is used, for example, chemical pulp (KP, SP, AP, etc.), mechanical pulp (SGP, RGP, CGP, TMP,
CTMP, SCP etc.), recycled pulp (DIP etc.), glass fiber, asbestos, slag rock,
Inorganic fibers such as aluminosilicate fibers and carbon fibers, and organic fibers such as polypropylene, polyethylene, nylon, acrylic fibers, aramid fibers, phenol-based, fluorine-based fibers and synthetic pulp are also included. Of these, chemical pulp is mainly used, and mechanical pulp may be added in an amount of 5 to 20% in order to improve the opacity of the final product. These pulps are appropriately blended according to the specifications of the final product, and subjected to mechanical treatment and various necessary internal additives to make paper.

As the internal additive added to the papermaking raw material containing pulp fibers as a main component, anionic acrylamide resin, cationic acrylamide resin, urea-formaldehyde resin, melamine-formaldehyde resin, polyethyleneimine, epoxy are used. Polyamide, Methylolated Polyamide, Polyvinyl Alcohol, Dialdehyde Starch, Positive Starch, Oxidized Starch, Carboxymethyl Cellulose, Hydroxyethyl Cellulose, etc. Examples include internal sizing agents such as sananhydride.

Of course, as a papermaking method for base paper, acidic papermaking,
The paper is arbitrarily made by neutral (alkali) paper making and is not particularly limited. Further, in these papermaking methods, talc, kaolin, heavy calcium carbonate and light calcium carbonate, and pigments such as titanium dioxide, calcined kaolin, and plastic pigment for improving opacity are appropriately internally added to the pulp slurry. .

Thus, the base paper is produced by using the paper stock in which various pulps and internal additives are appropriately mixed, but the structure of the paper machine is not particularly limited, and the Fourdrinier paper machine or the twin wire paper machine is used. Any of the above may be used, but it is particularly preferable to use a twin-wire paper machine because it is excellent in operability during cast finishing. Further, in order to improve the sizing degree of these base papers, the size of starch or the like is also surface-sized with a size press.

Further, in the method of the present invention, the pinholes of the base paper are coated, especially before the coating layer for casting is provided,
And for the purpose of reducing the coating amount of the cast coating layer,
Better results are obtained by previously providing the base paper with a dry weight of ^{2 to} 8 g / m < ² > per side on both sides. In this case, the undercoat coating layer is provided on the specific base paper described above, but the size and number of pinholes penetrating the undercoat coating layer are also important for obtaining the desired effect of the present invention. Can be a requirement. That is, the number of pinholes having a diameter of 0.05 mm or more and penetrating the base paper and the undercoating layer after the undercoating layer is provided is 35/100 cm ² or less, preferably 20/1
00 cm ² or less, more preferably 10 pieces / 100 cm
It is more desirable to adjust it to ² or less.

Incidentally, the number of the pinholes is 35/1
If it exceeds 00 cm ² , unevenness of permeation due to the permeation of the coating liquid for casting into the pinholes, quality of drum picks, drum blisters, etc., and operational problems occur when manufacturing lightweight double-sided cast coated paper. Is concerned.

As a method of adjusting the number of pinholes after the undercoat coating, it is needless to say that a base paper with few pinholes is used, but in addition, the pigment composition, the adhesive composition and the composition of the undercoat layer are also used. There are various methods such as the amount used and addition of auxiliary agents such as a flow modifier and a water resistance agent, and the method is not limited to a specific method. These methods are appropriately combined depending on the quality specifications of the final product.

Further, in the present invention, the Bekk smoothness (JIS-P-8119) of the surface of the undercoat layer is 50 to 100.
Even more excellent effects can be obtained by using a material adjusted to 0 second, preferably 100 to 500 seconds. When the Beck smoothness of the undercoat coating layer is within the above range, the coverage of the base paper pinhole by the undercoat coating layer is particularly improved, and the unevenness of penetration and the drum due to the penetration of the coating liquid for casting into the pinholes The quality of picks, drum blisters, etc., and operational difficulties are significantly improved. Further, a cast surface having excellent gloss and smoothness can be obtained even when the coating layer for casting has a low coating amount. As a method of adjusting the Beck smoothness of the surface of the undercoat layer to the above range, for example, after applying the undercoat layer, a smoothing treatment such as calender super calender or brushing is appropriately performed. It

Incidentally, when the Bekk smoothness of the surface of the undercoat layer exceeds 1000 seconds, the air permeability of the base paper provided with the undercoat layer becomes high, and as a result, the production of double-sided cast coated paper There is a risk of problems such as a reduction in speed and operational problems such as drum picks and blisters. Meanwhile, 5
If it is less than 0 second, the coverage of the base paper pinhole by the undercoat coating layer tends to be poor, and the desired effect of the present invention may not be easily obtained.

In the present invention, examples of the pigment used in the undercoat layer include kaolin, plastic pigment, light calcium carbonate, heavy calcium carbonate,
Aluminum hydroxide, barium sulfate, satin white,
Examples are talc, calcined clay, titanium dioxide and the like. One or more of them are appropriately selected and used. Among them, the combination of kaolin and light calcium carbonate and / or heavy calcium carbonate and titanium dioxide is particularly preferably used.

Examples of the adhesive used together with the pigment in the undercoating layer include casein, soybean proteins, styrene / butadiene copolymers, methyl methacrylate / butadiene copolymers and other conjugated diene polymer latexes, Acrylic polymer latex such as polymers or copolymers of acrylic acid ester and methacrylic acid ester, vinyl polymer latex such as ethylene / vinyl acetate copolymer, or these various polymers or copolymers having a carboxyl group Alkali-soluble or alkali-insoluble polymer latex modified with a functional group-containing monomer such as polyvinyl alcohol, olefin
Synthetic resin adhesives such as maleic anhydride resin and melamine resin, starches such as positive starch, oxidized starch, esterified starch, cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose, etc. The conventionally known adhesives used may be used alone or in combination of two or more. The amount of adhesive used is important for improving the coverage of the pinholes on the base paper.
15 to 50 parts by weight, preferably 17 to 40 parts by weight, and more preferably 20 to 3 parts by weight, relative to 100 parts by weight of the pigment.
It is adjusted in the range of 0 parts by weight.

Further, for the purpose of improving the water resistance of the undercoat layer and the coverage of the base paper pinholes, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether and adipic acid. Polyfunctional epoxy compounds such as diglycidyl ester, zirconium ammonium carbonate, zirconium compounds such as zirconium acetate, urea-formaldehyde-based, melamine-formaldehyde-based, polyamide urea-formaldehyde-based, various water resistance agents such as glyoxal, and printability improving agents Can be appropriately added, and the addition ratio of these is used in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the pigment. Further, in the undercoat coating layer coating liquid, if necessary, various auxiliaries such as defoaming agents, colorants, lubricants and flow modifiers are appropriately used within a range that does not impair the desired effects of the present invention. It

The thus prepared undercoating coating liquid has a solid content concentration generally adjusted to about 40 to 70% by weight, and various coating devices generally used for producing coated papers such as blade coaters, Air knife coater, roll coater, reverse roll coater, bar coater, curtain coater, die slot coater, gravure coater, chanplex coater, size press coater, or on-machine or off-machine coater equipped with a lip type coater, etc. onto the base paper. It is applied in one layer or in two or more layers.

The coating amount of the undercoat coating layer is preferably in the range of about ² to 8 g / m ^{2 in} dry weight per one side.
After coating the base coating liquid on the base paper, it is dried or semi-dried, but in order to secure the effect of the present invention, the water content after the base coating is preferably dried to 5% by weight or less. After undercoating, calender, super calender,
It is desirable that smoothing treatment such as brush calendering is performed.

In the method of the present invention, a light-weight double-sided cast coated paper is produced by using the base paper or the base paper provided with the undercoat coating layer as a support, but the coating solution for casting is not particularly limited. However, a coating liquid containing a conventionally known pigment and an adhesive as a main component, which are generally used in the cast coated paper field, is appropriately used.

That is, as the pigment, for example, cast coating such as clay, kaolin, aluminum hydroxide, light calcium carbonate, heavy calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, plastic pigment, talc and calcined clay. Various conventionally known pigments are used alone or as a mixture of two or more kinds in the field of paper.

Examples of the adhesive include proteins such as casein and soybean protein, conjugated diene polymer latex such as styrene / butadiene copolymer, methyl methacrylate / butadiene copolymer, acrylic acid ester and methacrylic acid ester. Acrylic polymer latex such as polymer or copolymer, vinyl polymer latex such as ethylene / vinyl acetate copolymer, or these various polymers or copolymers containing a functional group such as carboxyl group Depending on the body, functional group modified alkali-soluble or alkali-insoluble polymer latex, polyvinyl alcohol, olefin / maleic anhydride resin, synthetic resin adhesives such as melamine resin, positive starch, oxidized starch, esterification Starch and other starches, carboxymethyl cellulose, hydroxyethyl Cellulose derivatives such as cellulose, conventionally known adhesives known for general coated paper, alone or used in combination. The amount of the adhesive used is adjusted in the range of 5 to 50 parts by weight, generally 10 to 30 parts by weight, based on 100 parts by weight of the pigment.

On the other hand, diglycerol polyglycidyl ether, glycerol polyglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and diglycidyl adipate for the purpose of improving the water resistance and blocking resistance of the surface of the cast coated paper. Polyfunctional epoxy compounds such as ester, ammonium zirconium carbonate, zirconium compounds such as zirconium acetate, urea-formaldehyde system,
Various water-proofing agents such as melamine-formaldehyde type, polyamideurea-formaldehyde type, and glyoxal, and printability improving agents can be added as appropriate. Incidentally, the addition ratio of these is 0.1 to 5 with respect to 100 parts by weight of the pigment.
Adjusted in the range of parts by weight.

Further, in order to improve the releasability of the cast coating layer from the heated mirror surface of the drum surface, a releasing agent is appropriately added. Examples of the releasing agent in this case include fatty acids such as stearic acid, oleic acid and palmitic acid and salts thereof such as calcium, zinc, sodium and ammonium, stearic acid amide, ethylenebisstearic acid amide and methylenebisstearic acid amide. , Hydrocarbons such as microcrystalline wax, paraffin wax and polyethylene wax, higher alcohols such as cetyl alcohol and stearyl alcohol, oils and fats such as funnel oil and lecithin, and various surfactants such as fluorine-containing surfactants Examples thereof include fluoropolymers such as tetrafluoroethylene polymer and ethylene-tetrafluoroethylene polymer. These release agents are added in an amount of 0.1 to 30 parts by weight, preferably 0.2 to 10 parts by weight, based on 100 parts by weight of the pigment.

Further, sodium chloride, ammonium chloride, zinc chloride, magnesium chloride, sodium sulfate, potassium sulfate, ammonium sulfate, zinc sulfate, magnesium sulfate, ferrous sulfate, sodium nitrate, ammonium nitrate, monobasic sodium phosphate, ammonium phosphate, phosphoric acid Calcium, sodium polyphosphate, sodium hexametaphosphate, sodium formate, ammonium formate, sodium acetate, potassium acetate, sodium monochloroacetate, sodium malonate, sodium tartrate, potassium tartrate, sodium citrate, potassium citrate, sodium lactate, sodium gluconate , Sodium adipate, sodium dioctyl sulfosuccinate, methylamine, diethanolamine, diethylenetriamine, diisopropylamine, etc. Ammonium salts and metal salts of acids and organic acids, and can be added directly or in the form of a chelate or complex amines such as glossing aid. Furthermore, dispersants, defoamers, colorants, fluorescent dyes, which are used in the production of general coated paper and cast coated paper,
Various auxiliaries such as antistatic agents and preservatives are appropriately added and used together. The coating composition for casting composed of the above materials is generally prepared to have a solid content concentration of about 40 to 65% by weight.

Then, the above coating composition for casting is applied by various known coating devices such as a blade coater, an air knife coater, a roll coater, a brush coater, a chanplex coater, a bar coater, a gravure coater, or a lip type coater. A dry weight of ² to 20 g / m ² on the above-mentioned base paper, and a dry weight of 0.5 to 1 in the case of a base paper having an undercoat layer as the base paper.
2 g / m ^2, preferably from 1 to 10 g / m ^2, more preferably Kabusare coating to be about 2~9g / m ^2, after application, the wet casting method, the rewet casting method, or gelation casting method It will be gloss finished by either casting method.

[0036]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
In the examples, parts and% are parts by weight and% by weight, respectively, unless otherwise specified.

Examples 1 to 12 and Comparative Examples 1 to 3 Pulp shown in Table 1, Canadian standard freeness (beating) of pulp, sizing agent, paper strengthening agent, ash content, type of paper machine,
The base material was prepared according to the base paper, and the base paper was made. The pulp composition in Table 1 is the number of parts of NKP, LKP and GP based on 100 parts by weight of the total pulp, and the amount of the internal additive added is the ratio of addition per pulp.

As a pigment, 40 parts of kaolin and 25 parts of light calcium carbonate, 20 parts of heavy calcium carbonate, 15 parts of titanium dioxide, and as an adhesive, 5 parts of oxide (solid content) and styrene / butadiene co-weight per 100 parts of pigment. A coating liquid for an undercoat coating layer having a concentration of 60% and containing 20 parts (solid content) of the coalesced latex and 1.5 parts of zirconium ammonium carbonate was prepared. The coating liquid thus obtained is coated on both sides of each base paper shown in Table 2 with a blade coater so as to have a predetermined coating amount, dried, and then subjected to a super calendering treatment so as to have a predetermined Beck smoothness. Then, an undercoat base paper for double-sided cast coated paper was obtained.

Further, as a coating liquid for casting, 60 parts of kaolin, 40 parts of light calcium carbonate, 12 parts of 15% aqueous casein solution dissolved in ammonia (solid content), 15 parts of styrene-butadiene copolymer latex (solid content). ,
1 part of ammonium stearate was added as a release agent to prepare a coating liquid for casting having a solid content concentration of 50%. After this coating liquid was coated on the above-mentioned base paper for cast coated paper, cast finishing was carried out by a wet cast method.

That is, the above cast coating liquid was coated on the above base paper for cast coated paper so as to have a dry weight as shown in Table 2, and this paper was immediately subjected to a surface temperature of 80 ° C. with a press roll. It was pressed against a cast drum, dried, and peeled off to obtain a cast coated paper (precast).

Next, this one side finished cast coated paper was again subjected to cast finishing (post-casting) on both sides (opposite side) in the same step to obtain a double side cast coated paper.
The quality evaluation results of the double-sided cast coated paper thus obtained are shown in Table 2. The evaluation methods and the like shown in Table 2 are as follows.

[Pinhole] The number of pinholes having a diameter of 0.05 mm or more per 100 cm ^{2 of the} base paper and the base paper for undercoating was observed and measured with a stereoscopic microscope.

[Coating amount] The coating amount per one surface of the undercoating coating liquid and the casting coating liquid was expressed as a dry weight.

[Beck Smoothness] The Beck smoothness of the surface of the undercoating layer was measured according to JIS-P-8119.

[White Paper Gloss] The white paper gloss on the surface of the double-sided cast coated paper was measured by measuring the front cast surface and the rear cast surface according to JIS-P-8142, and expressed as an average value.

[Permeation unevenness] Permeation unevenness on the front cast surface of the double-sided cast coated paper was visually evaluated according to the following criteria. ⊚: There is no penetration unevenness. ◯: Permeation unevenness is slightly present. Δ: There is uneven penetration, but there is no problem as a product. X: The penetration unevenness is remarkable.

[Drum Pick, Drum Blister] The drum pick and drum blister generated at the time of the cast finish of the double-sided cast coated paper were evaluated according to the following criteria. A: There is no drum pick or drum blister. ◯: Drum picks and drum blisters are slightly present, but there is no problem in operation. Δ: There are drum picks and drum blisters, but there is no problem in operation. ×: Drum pick and drum blistering occurred remarkably,
It is difficult to operate.

[Opacity] The opacity of the double-sided cast coated paper was measured according to JIS-P-8138.

[Gloss unevenness] The gloss unevenness on the surface of the double-sided cast coated paper was visually determined according to the following criteria. ◯: There is no uneven gloss. Δ: Uneven gloss is observed. X: Many uneven glosses are seen.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

As is clear from the results of Tables 1 and 2, by using the specific base paper of the present invention, a high-quality lightweight double-sided cast coated paper could be stably produced.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuro Imai 1 Yoshida, Toyomae-cho, Anan-shi, Tokushima Kanzaki Paper Co., Ltd. Tomioka Mill

Claims (3)

[Claims] 1. A method for producing a double-sided cast coated paper, comprising: providing a cast coating layer containing a pigment and an adhesive as main components on a base paper, and finishing the wet coating layer by pressing against a mirror surface drum. The base paper has a weight of 45 g / m ² or less, the double-sided cast coated paper (product) has a weight of 65 g / m ² or less, and a diameter of 0.05 m that penetrates the base paper layer of the base paper.
A method for producing a double-sided cast coated paper, which comprises using a base paper in which the number of pinholes of m or more is 100/100 cm ² or less. 2. An undercoat coating layer containing a pigment and an adhesive as a main component on both sides of the base paper described above in a dry weight of 2 to 8 per side.
The number of pinholes having a diameter of 0.05 mm or more and penetrating the base paper coating layer after coating and drying so as to be g / m ² and providing an undercoat coating layer is 35/100 cm ² or less. A method for producing a double-sided cast coated paper according to claim 1. 3. The Bekk smoothness (JIS-P-8119) of the surface of the base paper coating layer after providing the undercoat coating layer is 50 to 10.
It is 00 seconds, The manufacturing method of the double-sided cast coated paper of Claim 2.