JPH02229293A - Finishing of cast-coated paper - Google Patents

Abstract

PURPOSE:To obtain the product having extremely improved luster and smoothness of cast surface and back coated layer by threading cast-coated layer to a calender consisting of a metallic roll and an elastic roll having specified material, hardness, surface roughness, etc. CONSTITUTION:First, one side of base paper is provided with cast-coated layer consisting essentially of pigment and an adhesive and the back is supplied with a coated layer of cast-coated layer consisting essentially of pigment and an adhesive to give cast-coated paper. Then the cast-coated layer is threaded to a calender consisting of a metallic roll having 15-30 deg.C surface temperature and a synthetic resin roll having >=75 deg.C Shore hardness and surface roughness Rmax defined by JIS B 0651 satisfying the formula [Rmax is surface roughness (mum) of elastic roll after breaking-in; D is Shore hardness D of metallic roll; T is surface temperature ( deg.C) of metallic roll during operation with the proviso that T is 15-300] to finish the cast-coated paper.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a method for finishing cast coated paper, and in particular to a double-sided cast coated paper that has excellent operability during finishing of cast coated paper and has no difference between the front and back sides. "Prior art" relates to a finishing method for single-sided cast-coated paper with excellent smoothness and gloss of the back coating layer and extremely improved printability.Highly glossy coated paper for printing called cast-coated paper. The manufacturing methods include the wet casting method, in which the wet coating layer is pressed against a heated drum with a mirror surface and dried to give a glossy finish;
A gel casting method in which the wet coating layer is made into a gel state and dried under pressure on the surface of the heated drum to give a glossy finish.After the wet coating layer is once dried, it is plasticized with a re-wetting liquid and then heated. A wet casting method is known, in which the material is pressed and dried on the drum surface.

The principle behind these casting methods is that the coating liquid, which mainly contains pigments and adhesives, contains water and is dried by pressing it against a heated mirror surface while it is in a wet state, and is released from the mold to create a strong gloss finish. It is common to

Most of the cast-coated papers produced according to the manufacturing method described above actually have a highly glossy cast finish on one side, and the other side has a high-quality paper-like surface. be.

By the way, cast coated paper has the highest gloss and smoothness as a coated printing paper, and when printed, it produces a unique beautiful finish that cannot be obtained with other coated printing papers. is a feature. For this reason, conventionally, so-called double-sided cast-coated paper, which has a mirror finish on both sides, and back-coated cast-coated paper (single-sided cast coated paper) with a back coating layer provided so that the back side has the same printing effect as the cast side. Coated paper) is requested.

To produce double-sided cast coated paper, first one side of the base paper is coated with a coating liquid mainly composed of pigments and adhesives, and while the coating liquid is in a wet state, it is pressed against a heating drum with a mirror surface. After drying and giving it a glossy finish, it is wound up once or successively again on the opposite side with the same coating solution as above, and while it is still wet it is coated on a heated drum in the same way as previously used. The method used is to apply pressure and dry to create a glossy finish on both sides. However, when producing double-sided cast coated paper using this method, there are problems that must be solved that are different from those for single-sided cast coated paper. In other words, in terms of quality, water in the paint that will be cast finished later is rapidly generated as steam during the heating and drying process, and passes through the base paper layer and the specular gloss coated layer that has been cast finished first. and evaporates, drastically reducing the smoothness and gloss of the pre-cast surface. For this reason, the difference in white paper quality between the front and back sides becomes significant, making it impossible to obtain cast-coated paper without double-sidedness, that is, with little difference between the front and back sides.

Furthermore, in the case of single-sided cast coated paper with a coating layer provided on the back side, there is a problem in that the smoothness of the back coating layer is extremely reduced, impairing printability, for the same reason.

``Problems to be Solved by the Inventionj'' The present invention is directed to a double-sided cast coated paper with excellent coating layer surface quality and operability, and a double-sided cast coated paper (with no difference between the front and back sides), and the smoothness and printing of the back coating layer. To provide a method for efficiently finishing single-sided cast coated paper with excellent suitability.

``Means for Solving the Problems'' The present invention has a cast coating layer mainly composed of pigment and adhesive on one side of base paper, and a coating layer mainly composed of pigment and adhesive on the back side. In a method for finishing cast-coated paper having a cast-coated layer, the cast-coated paper is heated with a metal roll having a surface temperature of 15 to 300°C and a Shore D hardness of 75.
Surface roughness R defined in JIS B 0651
This is a method for finishing cast coated paper, which is characterized by passing it through a calender made of a synthetic resin roll whose maκ satisfies the following formula.

Rmax <15+0.1 D O. In the 02T formula, each symbol is as follows. Rmax: Surface roughness of elastic roll after running-in (
μm) D=Shizier D hardness of elastic roll (°) T: Surface temperature of metal roll during operation ("C) (temperature range; 15-300
C) "Function" The finishing method of the present invention is characterized firstly in that it exhibits extremely excellent effects when applied to finishing double-sided cast coated paper.

Therefore, first, the finishing of double-sided cast coated paper will be described. The method for manufacturing double-sided cast-coated paper is to dry the coated layer formed on one side of the base paper while it is still wet, by pressing it onto the surface of the first heating drum that has a mirror surface to give a cast finish on one side. Single-sided cast coated paper is either rolled up once or continued as it is, and while the coating layer formed on the opposite side is still wet, it is pressed and dried again on the surface of a heating drum with a mirror surface to give it a cast finish. It is. In the above cast coating method, the period when the coating layer is in a wet state refers to the wet state when the coating layer is coated with a pigment coating liquid whose main components are pigment and adhesive, The coating layer may be dried and then re-wetted with a wetting liquid, or the coating layer may be applied with a coating liquid and then gelled with a gelling liquid.
That is, the method for manufacturing cast coated paper applied in the finishing method of the present invention is not particularly limited, and may include wet casting, rewet casting, gel casting, etc., and the same casting method may be used on both sides. It is not necessary, and can be produced by combining any suitable methods, such as wet casting on one side and wet casting on the other side. The double-sided cast-coated paper used in the finishing method of the present invention is cast-finished on both the front and back sides as described above, but the first cast-finished side (
The gloss and smoothness of the surface (front surface) is lower than that of the surface (back surface) that is later cast-finished, resulting in a double-sided cast-coated paper with a large difference in white paper quality between the front and back sides. It is not possible to obtain double-sided cast coated paper with high quality.

The reason for this is that, as mentioned above, when the back side is later cast finished, the moisture in the paint rapidly turns into water vapor during the heating drying process on the cast drum, causing the surface of the mirror-glossy coated layer that was previously cast finished (cast This is because the smoothness and gloss of the previously cast surface are extremely reduced because the particles rapidly pass through the surface and dissipate. Conventionally, in order to prevent this difference between the front and back surfaces, methods have been used to control rapid water evaporation by increasing the concentration of the paint used for later casting finishing, or by lowering the surface temperature of the casting drum. There is. However, even if the paint concentration is increased, the amount of evaporated water decreases only slightly, so almost no improvement effect can be expected, and if the surface temperature of the cast drum is lowered, the production speed of cast-coated paper will be extremely reduced. However, as a result, not only the productivity decreases, but also the effect of improving double-sidedness (difference between front and back sides) is slight, and the present situation is that a satisfactory double-sided cast coated paper has not been obtained.

In order to obtain double-sided cast-coated paper with no difference between the front and back sides, the present inventors constructed double-sided cast-coated paper using elastic rolls consisting of a chrome-plated metal roll and an ordinary cotton roll in the manner described below. I completed the single-sided 5-tier super calender.

That is, the double-sided cast coated paper was pressed and passed so that the rough side was in contact with a metal roll and the specular glossy side was in contact with an elastic roll. As a result, the rough side that was pressed against the metal roll recovered to its original specular and glossy surface, but the mirror side that was pressed against the elastic roll significantly deteriorated in both smoothness and gloss, and the original cast Coated paper quality could not be obtained. Cast coated paper has a mirror-like smoothness and gloss that is superior to art paper, coated paper, etc., so passing it through a conventional super calender for coated paper will actually reduce the smoothness and gloss. I understand. This is because when the cast surface (back surface), which is highly glossy and has a mirror-smooth finish after cast coating, is pressed against an elastic roll and passed through a calender, it is intended to copy the surface roughness of the elastic roll. This is because the smoothness and gloss of the cast surface are significantly reduced, and the cast coated paper loses its specular gloss.

In light of the above-mentioned circumstances, the inventors of the present invention have conducted intensive studies and research in order to increase the productivity of double-sided cast-coated paper and to obtain high-gloss cast-coated paper without double-sidedness (difference between front and back sides). As a result, after double-sided cast coating, when the paper is finished by passing it through a calender consisting of a metal roll and an elastic roll whose material, hardness, surface roughness, etc. have been specified, the reduced smoothness and gloss of the first cast surface is reduced to the second cast surface. The quality can be improved to the same level as the smoothness and gloss of the paper.In addition, in the case of single-sided coated cast coated paper with a coating layer on the back side, cast coating is performed first for the same reason as above.
If a back coating layer is applied later, the gloss and smoothness of the back coating layer will be significantly impaired, so if the cast coating layer is applied first and then the back coating layer is applied later, the gloss and smoothness of the back coating layer will be significantly impaired. It was found that passing the paper through a conventional super calender for coated paper, as in the case of double-sided cast coated paper, actually reduced the smoothness and gloss, so in this case as well, single-sided coated cast paper When finishing coated paper by passing it through a calender made of metal rolls and elastic rolls whose material, hardness, surface roughness, etc. They have found that this can be effectively improved and have finally completed the present invention.

Calenders made of a combination of metal rolls and elastic rolls used in the method of the present invention include, for example, super calenders, gross calenders, soft calenders, and Manto Online Calenders (Gi Balp Technology Times). , August 1962 issue, pp. 31-36.
PP ■, 1987 January issue, pages 45-47; revenge FP,
1985, 22.873-877. TAPI
I. Coating conferences 198
8, pp. 307-315) are used in on-machine or off-machine form with a cast coater.

For gear render finishing of double-sided cast coated paper,
The rough front cast surface (surface) is brought into contact with the metal roll and the rear cast surface (2lI surface) is brought into contact with the elastic orifice, and is used in multi-stage calenders that have an elastic roll in the middle. brings the post-casting surface (back side) into contact with the final metal roll surface. In addition, in the case of calender finishing of cast coated paper with one side coated, the paper is passed so that the cast side hits the metal roll and the back coated side hits the elastic roll, and in the case of a multi-stage calender, the paper is cast to the final metal roll. It is preferable that the surfaces touch. In this way, in the method of the present invention, the previously cast surface (surface), which is rough after finishing the cast, is restored to its original specular luster by the calendering process under specific conditions.
Improved.

The metal roll of the calender used in the method of the present invention must have a surface temperature in the range of 15 to 300°C, more preferably 20 to 250°C during operation. Incidentally, if the surface temperature of the metal roll is less than 15°C, the effect of improving the smoothness and gloss of the roughened cast surface will not be fully exhibited, and if it exceeds 300°C, the moisture content of the cast coated paper will decrease and the paper texture will deteriorate. This defect causes problems with poor paper passing through the printing machine. Further, the metal roll preferably has a surface roughness Rmax of 3 μm or less, and is desirably mirror-finished by hard chrome plating or the like.

The elastic roll may be a synthetic resin roll whose material is a thermosetting resin or a thermoplastic resin having a glass transition temperature (T g ) of 100° C. or higher, such as epoxy resin, polyamide resin, polyimide resin, or polyamideimide resin. Resins, polyurethane resins, silicone resins, polyacrylate resins, vinylidene fluoride resins, unsaturated polyester resins, polyacetal resins, phenol resins, polyphenylene sulfide resins, etc. are used.

Furthermore, the elastic roll used in the method of the present invention has a surface roughness Rmax (JIS B 065
1 method)).

Rsax <15+0.1 D -0.027 where,
Each code is as follows.

Rmax: Surface roughness (μ
m) D: Shore D hardness of the elastic roll (°) T: Surface temperature of the metal roll during operation (°C) (temperature range; 15~
300°C) As is clear from the above formula, the softer the Shore D hardness of the elastic roll used in the method of the present invention, and the higher the surface temperature of the metal roll, the more Since the deformation under nip pressure increases, that is, the tendency for surface roughening increases, it is necessary to reduce the surface roughness Rmax of the elastic roll accordingly.

Therefore, when the surface temperature of the metal roll is 20° C. or higher, it is particularly preferable that the surface roughness Rmax of the elastic roll satisfies the following formula by a method according to JIS 80651 method.

Rmax <13+0.1 D -0.02T In the formula, each symbol is as follows.

R++aκ: Surface roughness (μ
m) D The bielastic roll has a hardness (″) T: Surface temperature of the metal roll during operation (°C) (temperature range; 20~
250°C) According to the experimental results of the present inventors using a super calender, for example, the surface roughness RffIax was set to 5 μm.
Even with the following finely polished elastic rolls, double-sided coated paper is applied at a speed of 50 m/min or more, with the surface temperature of one metal roll raised to 50°C or more, and with a linear pressure of 10 Qkg/am or more. After pressure treatment, it became clear that the surface roughness of the adjacent elastic rolls rapidly increased due to unevenness caused by uneven formation and coating of the cast coated paper during operation. In particular, in the case of cardboard such as Castpost I paper, the texture is uneven and the smoothness under pressure is poorer, so the surface roughness of the elastic roll increases significantly under pressure, and the hardness is low. It has become clear that this tendency is even more pronounced when an elastic roll or an elastic roll made of a material that is easily deformed or a material that has low restorability is used.

Therefore, in the method of the present invention, the material of the elastic roll has good heat resistance under pressure, has little deterioration of surface roughness,
Epoxy resins, polyamide resins, polyimide resins, polyurethane resins, silicone resins, polyacrylate resins, vinylidene fluoride resins, unsaturated polyester resins, polyacetal resins, and phenolic resins with excellent restorability. , is characterized by the use of an elastic roll made of synthetic resin such as polyphenylene sulfide resin, but according to detailed experiments by the present inventors, among the above resins, epoxy resin Resins, polyamide-based resins, polyimide-based resins, polyamide-imide-based resins, and polyurethane-based resins were particularly preferred because they had a slow deterioration rate in surface roughness.

Conventionally, the use of synthetic resin elastic rolls in calenders has been applied particularly to the finishing of magnetic tapes (Japanese Patent Laid-Open No. 51-92606, Japanese Patent Publication No. 64-120).
No. 5, etc.). However, magnetic tape has a thickness of about 20 mm as a base material.
Because it is coated on a uniform film of μm polyethylene terephthalate, etc., there is no phenomenon in which the surface roughness of the elastic roll decreases over time during calendering and causes quality defects, and the initial surface roughness and No attention has been paid to the material of the roll for this purpose.

Elastic rolls made mainly of natural fibers (compounding at least 70% by weight) such as cotton, filmapto cotton, white cotton, and woolen paper paper, which have traditionally been used in super calenders for coated paper, are
As already mentioned, the surface roughness deteriorates rapidly during calender operation, and continuous operation is poor. Also, it was not suitable for finishing methods for single-sided coated cast paper, which has excellent printability.

As typical materials for the elastic roll used in the method of the present invention, specific composition examples are shown from among the resins mentioned above. Of course, the present invention is not limited to these examples.

First, epoxy resins include epoxy compounds that have two or more highly reactive epoxy groups in their molecules, and compounds that cause a curing reaction by reacting with epoxy groups such as amines and acid anhydrides (hereinafter referred to as curing agents). Thermosetting resins obtained by the reaction described above can be used, but as long as the thermosetting resin is polymerized and cured using two or more raw materials, it is limited to the above two types, including modified products thereof. It's not a thing. The epoxy compound can be used alone or in combination with two or more types of epoxy compounds, such as EBS type, alicyclic type, novolak type, glycidyl ester type heterocyclic type, etc.
Epoxy resins are generally phenoxy types whose main components are the following formula: }, polyamide resins, aromatic polyamines, organic acids, organic acid anhydrides, urea, combinations of melamine resins, combinations of aniline/formaldehyde resins, and carbonic acid resins. Can be used in combination. Epoxy resins are often used in combination with fillers.

Typical examples of epoxy resins include Epicoat 1001 and 1009 manufactured by Shell Chemical ■. 828 etc. are mentioned.

Polyurethane resins are called polyurethane resins and hard polyurethane rubbers, and as shown by the following formula, they contain urethane bonds in their composition. U is used. In this case, the curing agent used in combination includes aliphatic polyvalent amines (4+-0-C-
N-Rz-N-C-0-R+ -0-C-N-Rt- For example, in the above formula, R. When is a linear compound and R2 is an aromatic compound, a polyurethane rubber is obtained.

Next, polyamide resin will be described. The polyamide resin referred to herein is a condensation polymer having an acid amide bond (-CONH-) in its main chain.

For example, the following methods are used to make polyamide resin. (1) Bond between diamine and dicarboxylic acid: FlKN-
(R+)t-NFI! + HOOC- (Rz)
--Cool- (HN-(R+)t-NHCO-(
Rz)a-Co) +HzO(2》 Amino acid bond: HJ-Rs-Coo}I→(HN-Rs-CO) +
Ring opening of FIzO(3} lactam: In the above formulas (1) to (3), R+SRz and R4 are divalent groups having 1 to 20 carbon atoms: R, is 2 having 1 to 10 carbon atoms
It represents a valence group, and 1, m and n each represent 0 or 1. Preferred examples of R include alkylene or alkenylene having 1 to 20 carbon atoms, cyclohexanediyl, phenylene, tolylene, xylylene, naphthylene, biphenylylene, and the like. Preferred examples of R2 include alkylene or alkenylene having 1 to 20 carbon atoms, cyclohexanediyl, phenylene, tolylene, xylylene, naphthylene, biphenylylene, and the like.

R is alkylene having 1 to 10 carbon atoms, or alkylene having 1 to 10 carbon atoms;
Preferred are carboxyl-substituted alkylene having 10 carbon atoms, phenyl-substituted alkylene having 1 to 10 carbon atoms, and the like.

As R4, alkylene having 1 to 20 carbon atoms is preferable.

Further, the dicarboxylic acid of the formula (1) may be an anhydride, an ester, etc., and the amino acid of the formula (2) may be an anhydride. moreover,
Examples of diamines of formula (1) include hydrazine, methylene diamine, dimethylene diamine, trimethylene diamine, tetramethylene diamine, pentamethylene diamine, bentamethylene diamine, hexamethylene diamine, hebutamethylene diamine, octamethylene diamine, and Methylene diamine, decamethylene diamine, biverazine, diaminoxyhexane, di(aminomethyl)
Cyclohexane, bis(α-aminocyclohexyl)methane, bis(4-amino-1,2-methylcyclohexyl)methane, 0-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminobif Dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adivic acid, bimelic acid, succinic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, Decanedicarboxylic acid, undecacydicarboxylic acid, dodecanedicarboxylic acid, hexadecanedicarboxylic acid, tabsiaic acid, maleic acid, fumaric acid, citragonic acid, diglycolic acid, malic acid, citric acid, phthalic acid, isophthalic acid, terephthalic acid, maleic anhydride Acid, phthalic anhydride, etc. are used.

The amino acid (aminocarboxylic acid) of formula (2) is α-
Aminoacetic acid, L-α-aminobrobionic acid, L-α-aminoisovaleric acid, δ-aminocabronic acid, L-α-
Aminoisocaproic acid, L-α-amino-β-phenylprobionic acid, L-aminosuccinic acid (aspartic acid)
, L-α-aminoglutaric acid (glutamic acid), γ-
Aminoacetic acid, α-amino-n-adibic acid, 1)-aminoundecanoic acid, α-amino-DL-isoamyl acetic acid,
α-amino-monoacetic acid, 2-amino-2-methylacetic acid,
α-aminocabric acid, α-aminocapric acid, 1-
Aminocyclohexanecarboxylic acid, α-aminocyclohexyl acetic acid, 1-amino-αmethylcyclohexanecarboxylic acid, ethyl aminomalonate, β-benzyru-D-aspartate, β-benzyru-D-aspartate, γ
-Benzylu DL-glutamate, etc. are used.

Lactams of formula (3) include isocyanic acid, glycine anhydride, α-pyrrolidone, α-piperidone, γ-butyrolactam, δ-valerolactam, δ-kabulactam,
α-Methylcaprolactam, β-methylprolactam, γ-methylcaprolactam, T-methylprolactam, δ-methylprolactam, N-methylcaprolactam, βγ-dimethylcabrolactam, γ-ethyl Cabrolactam, T-isoprobylcabrolactam, δ-isoprobylcabrolactam, γ-butylcabrolactam, ζ-enantholactam, ω-enantholactam, η-cabryllactam, ω-cabryllactam, ω-Lauro Lactams etc. are used.

These polyamides are commonly called nylons. Specifically, nylon 1 is produced by the polymerization of isocyanic acid, nylon 2 is produced by the polymerization of N-carboxyamino acid anhydride, and β-
Nylon 3 by polymerization of aminopiparic acid, nylon 4 by ring-opening polymerization of α-pyrolidone, nylon 5 by ring-opening polymerization of α-biveridone, nylon 6 by ring-opening polymerization of ε-capsulactam, polymerization of ω-aminoenanthic acid. Nylon 7 by ring-opening polymerization of fogging lactam
nylon 8, nylon 9 from ω-aminononylic acid, nylon 10 by ring-opening polymerization of cabrin lactam, nylon 1) from 1)-aminoundecanoic acid, nylon 12 by ring-opening polymerization of ω-laurolactam, hexamethylene diamine Nylon 66 is produced by the polycondensation of hexamethylene diamine and adivic acid, and nylon 610 is produced by the polycondensation of hexamethylene diamine and sebacic acid. In addition, copolymers of these nylons, such as nylon 6/66/610 (copolymerization ratio:
10/40/5(1) can also be used.

Simply copolymers of these nylons with other monomers can also be used. Specifically, graft copolymers with vinyl monomers such as 2-methyl-5-vinylpyridine, styrene, methyl methacrylate, sodium acrylate, vinyl acetate, vinylidene chloride, and acrylonitrile; ethylene oxide, brobylene oxide, and ethylene imine. , cyclooxabutane, ε-cabrolactam, ethylene sulfide, evichlorohydrin, maleic anhydride, phthalic anhydride, hexahydrophthalic anhydride, dichloromaleic anhydride, dodecylsuccinic anhydride, and other ring-opening polymerizable monomers. copolymers, etc.

These can be carried out using conventional methods such as graft polymerization, acylation,
It can be made into a copolymer by alkylation or the like.

In addition, monomer cast nylon (Monomer cast nylon) is obtained by rapidly polymerizing lactam in the presence of a catalyst during ring-opening polymerization to form a polymer block.
Casting Nylon. MC NYLON) can also be used in the method of the invention.

The above-mentioned polyamide resin in the present invention may be made fine and uniform by adding a crystal nucleating agent. As a crystallizing agent, Pbz(PO4)t, NaHPOa, N
Phosphorus compounds such as a7PsO+a: corundum, rutile,
Kaolin, asbestos, graphite, MoSz, WS
Fine powder of ores such as , SiOz, talc, and polymer powders such as polyethylene terephthalate and polyethylene naphthalate are used.

Additionally, glass-reinforced materials may be used, such as incorporating glass fiber powder into polyamide resin, dispersing glass fibers in polyamide resin, or filling glass beads.
r-Glass Reinforced Thermo
Plastic) resin is used. or,
Polyimide resins and polyamide-imide resins synthesized in a similar manner to the above-mentioned polyamide resins can also be used. Polyimide resin is prepared by self-polycondensation of acid anhydride or its ester (α-aminophthalic anhydride, dimethyl-4-aminophthalate, etc.): #I method of polycondensation of anhydride and diamines, acid anhydride A soluble polyamic acid is obtained by reacting a compound with a diamine in an organic solvent, and is obtained by a method of performing intramolecular dehydration ring closure.

For polyimide resin, ACC is a typical example of molded product type.
Company's XPI-1a2, DIJ Pont Company's Ves-
pe1% Toray's No. 1 KC resin, TI-Volima Amoc
o company's Torlon resin, lJpj ohn company's Pot
Examples include yiwide 2080 resin, and aromatic polyimide resins are preferable.

Polyamide-imide resin is produced by reacting a low molecular weight polyamide with an amino group at the end with an acid anhydride; by reacting a low molecular weight polyamide acid with an amino group at the end with dibasic chloride: a trimellitic acid derivative and a diamine It can be obtained by a method such as a reaction.

Examples of acid anhydrides or derivatives thereof include biromellitic anhydride, pyromellitic acid-1,4-dimethyl ester, biromellitic acid tetramethyl ester, biromellitic acid ethyl ester, and 2,3,6,7-naphthalenetetracarboxylic acid. Dianhydride, 3.3', 4.4°-biphenyltetracarboxylic dianhydride,! , 2,5.6-naphthalenetetracarboxylic dianhydride, 2.2'. 3.3'-biphenyltetracarboxylic dianhydride, 2.2'. 6.6
'-Biphenyltetracarboxylic dianhydride and the like are used, and the diamines are the above-mentioned aromatic diamines.

Examples of solvents for synthesis of polyamic acid include dimethylformamide, dimethylacetamide, dimethylmethoxyacetamide, N-methylprolatacum, dimethylsulfone,
Tetramethrene sulfone, N-acetyl-2-pyrrolidone, etc. are used.

Aromatic polyester: The former is Unitika's U-polymer (U series, AX-
series), Carborundum's Econcl (101
), and the latter is represented by Teijin Kaseiichi's Pan lite series (Pan lite K-1300, etc.).

As the vinylidene fluoride resin, κF polymer (1000, 1) 100 series from Kureha Chemical Industry ■, Pe
κynar from nwaft Chemicals,
Du Pont's Du 1ite is a typical example.

The polyphenylene sulfide resin is an aromatic sulfide polymer whose main component is the structure shown by the following formula, such as Ryton AP-140 from Phillips and Asahi Glass ■A.
SAHI-PPS, Series, Shin-Etsu Chemical ■Shin-Etsu P
It is represented by the PS series, etc.

Polycarbonate: Phenol resin is a thermosetting resin whose main component is the structural formula shown below, which is produced by condensation of phenol and formalin.It is generally used not as a resin unit but as a combination of various fillers. As fillers, paper (bleached or unbleached), various fiber materials (glass, carbon, cellulose, etc.), wood flour, inorganic fillers (carbon, quartz, etc.), textiles, etc. are used. A typical example is Sumitomo Bakelite's Sumikon P.
M series, Sumilight resin PR series, etc.

Unsaturated polyester resins are produced by using maleic anhydride as represented by the following general formula in combination with phthalic anhydride or other saturated polybasic acids and esterifying them with polyhydric alcohols such as ethylene glycol and brobylene glycol. This is a resin obtained by polymerizing the unsaturated alkyd obtained by adding a polymerizable monomer such as styrene monomer.

Like phenolic resins, they are usually used in combination with various fillers.

(The most typical one is FRP.) A typical example is the Sumicon TM series.

Polyacetal resin mainly has the structure shown by the following formula. -{CH, -0+, polyether resin, which is practically represented by Du Pant's Delr resin, Celanese's Celcon resin, and polyplastic 10 Duracon resin.

The silicone resin is represented by the general formula: RaSiOn-a-zJb 11■111. Here, R represents a monovalent organic group. R
For example, an alkyl group such as a methyl group or an ethyl group, an alkenyl group such as a vinyl group or an aryl group, an allyl group such as a phenyl group or a naphthyl group, an aryl group such as a tolyl group, or a benzyl group. araalkenyl group,
Examples include halogenated alkyl groups such as trifluorobrobyl. a is a positive number from 1.1 to 1.9. In addition, χ is OH, OR'(R' represents a monovalent organic group,
It is an organic group as shown in the example of R), and a group that reacts to form a siloxane bond like hagen such as cl. b is a positive number of O<2.9. The silicone resin contains Mn, Zn, Fe, Co,
Organic acid salts of transition metals such as Ni and Pb, amines such as hexamethylene diamine and triethanolamine,
It is heat-cured using quaternary ammonium and mH salts thereof such as tetramethylammonium hydroxide and benzyltrimethylammonium hydroxide.

When this silicone resin is used in the elastic roll of the present invention, it is used in combination with 10 to 400 parts of filler.

As the filler, silica such as quartz powder with an average particle size of 5 microns or less, calcium carbonate, carbon blank, etc. are used.

In this silicone resin 1, for example, Don Cor
ning DC-304, DC-305, DC-30
6. Shin-Etsu Chemical 10KMC-8. 10. Examples include silicone molding compounds such as No. 12.

Typical polyarylate resins are aromatic polyester and polycarbonate.

Naturally, a suitable filler can also be added to impart a reinforcing effect. The filler in this case is not particularly limited, but fibrous materials with excellent heat resistance, solid fine powders, and fine particles are effective. Further, as the fiber material, a fiber material having excellent heat resistance and durability, such as rayon, glass fiber, carbon fiber, or steel cord, is used.

In addition, solid fine powders and fine particles include carbon black, α-FezC+s, Sing, colloidal silica, quartz powder, talcum powder, tungsten dioxide, molybdenum disulfide, boron fluoride, graphite, CrlO+
, Tie. etc. are used. The particle size of the filler is 1
A thickness of 0 μm or less can be used, and a thickness of 5 μm or less is particularly desirable. The amount of these fibrous and powder fillers to be added varies depending on the purpose of use, and it is difficult to determine the optimum amount.
Generally, addition of 1 to 20% of the resin is effective for improving heat resistance.

Regarding the hardness of the elastic roll, it is desirable to use a roll with Shore D hardness of 75° or more, considering durability under high temperature and high pressure and roughening resistance under paper passing, and a roll with a surface temperature of 20°C or more is preferable. In such cases, it is preferable to use an elastic roll having a Shore D hardness of 77° C. or higher. Further, when the temperature is 100°C or higher, a Shore D hardness of 80' or higher is more preferable.

Elastic rolls can have a single to multi-layer structure, inner layers made of different materials, and double-layered rolls with increased heat resistance toward the outer layer.
Any of the conventionally proposed structures, such as a roll made of a material such as No.

Furthermore, if the surface temperature of the elastic roll is as high as 100° C. or higher, the roll surface will rapidly become rough, so it is preferable to cool the elastic roll from inside or outside the roll with a cooling liquid or cooling air.

In addition, in the method of the present invention, the surface roughness R of the elastic roll
max ii'' is measured by the method defined in JIS B 0651, but since the calender roll width of ordinary coated paper for printing is about 1500 to 7500 am, the measured values vary considerably in the width direction of the roll. Therefore, for example, if the roll width is 2000 mm, use Surf test t201 manufactured by Mitoyo Seisakusho as a measuring device, set the measurement length L) to the maximum measurement length of 8 mm, and measure at least 10 times over the entire elastic roll (roll width). If 1) is wide, it is necessary to measure more times), and the surface roughness R max must be defined by the average value of the obtained measurement values.

Various processing conditions when surface treating coated paper with a calender are appropriate depending on the type of target cast coated paper, base paper conditions, properties of the coated layer, coating amount, paper moisture, finishing speed, etc. Although the surface temperature of the metal roll is controlled, the higher the surface temperature of the calender roll, the more the plasticization of the coating layer is promoted. Therefore, in the method of the present invention, the surface temperature of the metal roll is used in the range of 15 to 300°C. Incidentally, if the temperature is 300°C or higher, the difference between the front and back sides of the coated paper becomes significant due to roughening of the elastic roll under pressure, while if the temperature is lower than 15°C, good smoothness and gloss cannot be obtained.

The method of heating the metal roll may be any conventional method such as steam or electricity, and is not particularly limited.
For example, induction heating type jacket roller electric heating / 41
．． pp. 2-8, 1988, Paper Pulp Technology, T/6
(December 2013 issue, pages 41-47) is particularly preferred because it maintains temperature uniformity and avoids partial surface roughening due to localized heating.

Pressure conditions for calender rolls are approximately 10 to 500 linear pressure.
A range of about kg/cm is preferable, and a low pressure is preferable because the paper pressure can be kept high and the surface roughening of the elastic roll is difficult to proceed. The number of pressure nips per calender is usually 1 to 6 nips per drum or metal roll in the case of a soft calender or a gross calender.
If necessary, it is also possible to finish both sides using two calenders. In addition, in the case of super calendar one, 3 to 13
The average level is about 100%.

Therefore, during surface finishing, the cast coated paper comes into pressure contact with about 1 to 7 elastic rolls. Because it is not possible to measure the surface roughness under pressure when the elastic roll is in operation.
2 In the method of the present invention, after the elastic roll is run-in, the roll surface roughness (μIl1) at the time of stopping is measured and defined. The degree of surface roughness deterioration over time during operation of elastic rolls is as follows:
Although it varies depending on many conditions such as the basis weight of the coated paper, texture, uneven coating, moisture content, hardness of the elastic roll, temperature, pressure, speed, etc., if the provisions of the present invention are followed, it can be used continuously for a long time. Even during operation, it is possible to stably obtain double-sided cast-coated paper with no difference between the front and back sides and a cast-coated paper with a back-side coating excellent in smoothness on the back side. In addition, since it is the elastic rolls in the second half that have a large effect on the difference between front and back, when using a multi-stage calender, it is especially important to use a roll that meets the conditions of the present invention for one or two of the elastic rolls in the latter half. It may also be operated.

In this way, when the specific synthetic resin roll of the present invention is used in the latter half of the calender, it is also possible to use the generally known elastic rolls mentioned above as other elastic rolls in the conventional manner. be.

Of course, it is most desirable that all elastic rolls satisfy the conditions of the present invention. Particularly, in the method of the present invention, remarkable effects can be obtained in the case of thick cast coated paper having a basis weight of 100 g/m or more. As mentioned above, the heavier the basis weight, the more uneven the paper formation and uneven coating seen on the front and back sides of the coated paper become, so the smoothing improvement effect of the present invention becomes more pronounced. It is recognized that the tsubo is 1.20
g/m or more, the improvement effect is even more noticeable.

Furthermore, according to the experiments of the present inventors, the synthetic resin rolls used in the method of the present invention are cotton rolls made mainly of natural fibers, which are commonly used in conventional super calenders, etc., woolen paper rolls, and polyester rolls. Compared to fiber-based elastic rolls such as fiber rolls, aramid fiber rolls, asbestos rolls, and paper rolls, it is difficult to achieve smoothing accuracy after breaking-in, so the breaking-in of elastic rolls should be performed more carefully than under normal conditions. is desirable. The measurement conditions for the surface roughness after the break-in operation are a linear pressure of 100 kg/cm, and measurements are performed after the break-in operation is performed at 40° C. and 70° C. for 3 hours each.

Although there are no particular restrictions on the operating conditions for the roll, for example, after polishing the roll, the operating conditions are 40°C, 60°C, and 60°C without passing the paper through.
It was particularly effective to perform a break-in operation for 2 hours or more under each temperature condition while raising the temperature to 80°C.

The moisture content of the coated paper before entering the nip of the calender is preferably about 3 to 10%, and the finishing speed of the calender is generally 20 to 1000 m/min, although it largely depends on the weight of the paper, the paper type, etc. It is adjusted within a range of about minutes. In addition, we have installed water coating equipment using rolls, electrostatic humidification equipment, steam humidification equipment, etc. to control and humidify coated paper after surface treatment, and various types of equipment that have been publicly used in the field of coated paper manufacturing. It is of course possible to use appropriate combinations of techniques.

In the present invention, the coating composition used to form the coating layer contains pigments and adhesives as main components, similar to conventional cast coated paper compositions.

As the pigment, one or more types of ordinary pigments for coated paper, such as clay, kaolin, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, and plastic pigment, are selected and used as appropriate. Ru. Examples of adhesives include proteins such as casein, soybean protein and synthetic proteins, conjugated diene polymer latex such as styrene-butadiene copolymer, acrylic esters and/or
Alternatively, acrylic copolymer latex such as a polymer or copolymer of methacrylic acid ester, vinyl copolymer latex such as ethylene/vinyl acetate copolymer, or various polymer latexes thereof with functional groups such as carboxyl groups. Alkali-soluble or alkali-insoluble polymer latex modified with containing monomers, synthetic resin adhesives such as polyvinyl alcohol, olefin/maleic anhydride resin, and melamine resin, starches such as positive starch, oxidized starch, etc. , cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, and ordinary adhesives for coated paper, which are appropriately selected and used.

The amount of adhesive used is generally 5 to 50 parts by weight, more preferably 10 to 30 parts by weight per 100 parts by weight of the adhesive.

Various auxiliary agents such as antifoaming agents, colorants, mold release agents, flow modifiers, etc. are appropriately blended into the coating composition as necessary. An auxiliary agent that promotes gelation and a salt of a polyvalent metal such as zinc, aluminum, magnesium, calcium, barium, etc.
It is added in an amount of about 5 to 1031 U parts per part by weight.

Since the first feature of the present invention is to perform a cast finish on both sides, it is possible to use the same coating composition for coating both sides, but this may occur if the cast finish is applied later. The vapor passed through the base paper layer and the cast coating layer on the opposite side and was evaporated and dried.
Compared to cast-coated paper that does not have a coating layer on the opposite side, the production rate is significantly lower. Furthermore, due to rapid water evaporation, the coating layer on the previously finished cast surface swells and softens, resulting in a decrease in smoothness and gloss. For this reason, it is desirable to use a coating composition that is excellent in water resistance and vapor permeability for the coating layer in the case of first casting finishing.

Incidentally, as a method for imparting water resistance to the coating layer and improving vapor permeability, for example, zirconium compounds (ZrOz
) to the pigment in an amount of 0.05 to 3.
It is also good to contain 0% by weight, and it is also good to use cubic calcium carbonate as the pigment.

In addition, the coating composition for the back side of the back side cast coated paper can be the same as the coating composition for printing coated paper that has been generally used in the past, as well as the cast coating composition. can. Application equipment for the coating composition includes a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, a chamberx coater, etc., which are used in general coated paper manufacturing. A size press coater etc. can be used. The solid content concentration of the coating composition is adjusted to -a in the range of about 40 to 70% by weight, but considering the operability, it is 45 to 6% by weight.
A range of 5% by weight is preferred.

As the base paper, base paper or board paper with a weight of 30 to 400 g/nf, which is used for general printing coated paper and cast coated paper, is used, but the paper making method is not particularly limited. , alkaline paper may be used, and of course, medium-quality base paper containing high-yield valves can also be used.

The coating amount of the cast coating composition on the base paper is generally 5 to 35 g/rt (dry weight), but it depends on the quality of the resulting cast coated paper such as smoothness and gloss, and the cast coating speed. In terms of the improvement effect, it is desirable to adjust the amount within the range of 8 to 30 g/rtf.In addition, the coating amount on the back side is 5 to 30 g/rr in terms of dry weight in order to obtain good smoothness and printability.
r, more preferably in the range of lO to 25 g/rtf. Incidentally, if it is less than 5 glrrr, good smoothness and printability cannot be obtained, while if it exceeds 30 g/rd, the production rate will be significantly (decreased), so it is not preferable.Of course, the metal specified by the method of the present invention Even when paper is passed through a calendar using rolls and synthetic resin rolls,
If the coating amount is outside the above specified range, the desired effect cannot be obtained. Note that the rewetting liquid used in the rewet casting method includes, for example, water, polyethylene maelsion, fatty acid soap,
Add a mold release agent such as calcium stearate, microcrystalline wax, surfactant, funnel oil, etc. to about 0.0%. 01～
An aqueous solution or emulsion containing about 3% of the total weight is used. Next, when producing double-sided cast l paper, the steam generated during the later cast finishing is dried in a heated drum as described above, and the base paper layer and the cast coated layer on the opposite side are dried. The production speed is significantly lower than that of cast coated paper, which does not have a coating layer on the opposite side. Further, due to the rapid evaporation of water, the coating layer on the previously finished cast surface is swollen and softened, resulting in a decrease in smoothness and gloss. For this purpose, for example, improvements to the equipment include:
Hot air drying, gas heater, electric heater, infrared drying,
It is also good to perform auxiliary drying using high frequency, laser, electron beam, etc. In the case of auxiliary drying, it is recommended to adopt auxiliary drying using infrared rays, especially near infrared rays (wavelength: 0.75 to 2.5 pm, more preferably 1.0 to 2.0 μm) to solve the above problem. Most desirable for improvement. By the way, infrared rays have a wavelength of 0.75 to 2.5 μm, near infrared rays, and 2.5 to 2.5 μm.
Broadly divided into mid-infrared rays of 25 μm and far infrared rays of 25 to 2000 μm (Tebiki Kagaku Doujin of Instrumental Analysis/1979
However, conventionally used infrared dryers use only infrared rays in the mid-infrared region and far-infrared region, and do not use near-infrared rays.

In other words, red momme drying in the near-infrared region is a relatively new drying method. The reason why it is preferable to use near-infrared rays for auxiliary drying in the present invention is that near-infrared rays have a strong penetrating power through the coated layer and a high energy density. The wet coating layer can be gelled and dried instantly and uniformly, and the coating layer can be made bulky and has good coverage of the base paper surface, which improves the adhesion of the coating layer to the heating drum in the breath nip. gender is equalized,
This is because it is possible to obtain cast-coated paper with excellent high gloss without bottle-hole-like spots or uneven gloss.

Moreover, according to the method of the present invention, even if the smoothness and gloss of the cast coated paper surface after double-sided cast finishing are extremely low,
The specified calender finish of the present invention makes it possible to obtain double-sided cast-coated paper of excellent quality. For this reason, in the production of double-sided cast coated paper, unlike the conventional technology, there is no need to reduce the speed during back casting to improve double-sided properties, and it is possible to obtain double-sided cast coated paper with high productivity. It is something.

For the same reason, in the case of back-coated cast coated paper,
It is possible to obtain back-coated cast-coated paper having superior smoothness and printability with better productivity than conventional techniques.

"Example" The present invention will be described in more detail with reference to Examples below, but of course the scope is not limited thereto. Further, "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified. The evaluation method for each evaluation item is as follows.

[Surface roughness Rmax] Measurement length was 8ffiI with Surf test 201 manufactured by Mitoyo Seisakusho! It was measured as l.

[Visual difference between front and back]

The blank paper was visually observed, and the difference between the front and back sides was determined based on comprehensive quality evaluations such as gloss, smoothness, and texture.

◎; Very good O; Good Δ; Inferior ×; Extremely inferior [Glossiness] Measured according to JIS P 8142.

? Smoothness] Smoostar smoothness meter (DSM-01/manufactured by Toei Denshi)
(cmFtg). The smaller the number, the better the smoothness. Examples 1-2 Pigments: 70 parts of kaolin, 30 parts of light calcium carbonate, 10 parts of oxidized starch, 16 parts (solid content) of styrene-butadiene copolymer latex (trade name: SN-307/manufactured by Sumitomo Naugatac ■), A 60% coating solution containing 0.4 part of zirconium ammonium carbonate (as ZrO) as a water resistance agent was prepared.

The obtained coating liquid was coated on both sides of a 45 g/rd base paper using an on-machine blade coater so that the dry weight was 10 g/nf per side, and then dried to form a cast coated paper with dry coating layers on both sides. Got paper.

On the other hand, as a coating liquid for casting finishing, 80 parts of kaolin,
20 parts of cubic calcium carbonate with an average particle size of 0.5μI, 14 parts of casein (as an adhesive for 100 parts of pigment)
(solid content) and acrylic acid/butadiene/methyl acrylate (ratio: 2/33/65) copolymer latex 8 parts (solid content), 0 tributyl phosphate as an antifoaming agent
．． A coating liquid for cast coated paper was prepared with a concentration of 53%, consisting of 5 parts of zirconium ammonium carbonate (ZrO.) as a water-resistant agent, 0.4 parts of ammonium zirconium carbonate (ZrO.) as a water-resistant agent, and 1.0 parts of ammonium stearate as a mold release agent. Apply this coating liquid to one side of the base paper at a dry weight of 15 g/r.
d, and immediately dried under pressure on a first heated drum with a mirror surface heated to a surface temperature of 93°C at a rotational speed of 40 m/min, and then peeled off from the heated drum with a take-off roll and cast coated. After obtaining the coated paper (at this time, the temperature of the coated paper was 40° C1 and the moisture content was 4.5%), the above-mentioned cast coating liquid was continuously applied to the opposite side to a dry weight of 14 g.
/rrf, and immediately reduce the rotation speed to 35.
The paper was dried under pressure on a second heated drum having a mirror surface heated to a surface temperature of 85° C. at a speed of m/min, and then peeled off from the heated drum using a take-off roll to obtain a double-sided cast coated paper.

The double-sided cast coated paper obtained in this way was
The paper was passed through an on-cast soft calender finishing machine consisting of a chrome-plated metal roll with a diameter of 800 mm, an elastic roll with a diameter of 800 mm, and 2 nips at a linear pressure of 100 kg/el1 to perform surface finishing. The metal roll was heated using an induction heating method. An epoxy resin roll was used as the elastic roll. The roll conditions during operation, i.e., the Shore D hardness of the elastic roll, the surface roughness after running-in, the surface temperature of the metal roll during operation, etc., and the quality evaluation results of double-sided cast coated paper obtained through continuous operation are shown in the table. 1
It was shown to. Example 3 The same procedure as in Example 1 was carried out, except that a polyamide-imide resin roll was used as the elastic roll, the surface temperature of the metal roll was 250°C, the Shore D hardness was 96°, and the surface roughness after running-in was 4 mμ. The surface of the double-sided cast coated paper was finished. Conditions during operation, i.e. Shore D hardness of elastic roll, surface roughness after breaking-in operation. Table 1 shows the surface temperature of the metal roll during operation and the quality evaluation results of double-sided cast coated paper obtained during continuous operation. Example 4 The coating liquid for cast finishing prepared in Example 1 was
The dry weight on both sides of the base paper is 28 g /
It was coated using an air knife coater and dried to give rrf. Next, a rubber roll with a diameter of 750 ms+ and a diameter of 15
The paper is passed through a press nip formed by a heated drum with a mirror surface of 0.00 m, and the surface of the coated layer is re-wetted with a re-wetting liquid (0.5% concentration) supplied from a nozzle and made of polyethylene emulsion. After that, press pressure 200 on a heating drum with surface temperature 105°C and rotation speed 120 m/min.
kg/cm, and after drying, it is peeled off from the heating drum with a take-off roll, finished by casting, and wound up.
After the coating layer surface is rewetted with a rewetting liquid (0.5% concentration) consisting of a polyethylene emulsion supplied from a nozzle, the surface is A press pressure of 200 kg is applied to a heated drum at a temperature of 105°C and a rotation speed of 80 m/min.
/CI, and after drying, it was peeled off from the heating drum with a take-off roll, finished with double-sided casting, and then wound up.

The thus obtained double-sided cast coated paper was subjected to a linear pressure of 150 kg/C using a 5-stage super calender! ! , speed 20
Finished under the condition of 0 m/min. A polyimide resin roll was used as the elastic roll at this time. The table also shows the operating conditions and the quality evaluation results of double-sided cast-coated paper obtained during continuous operation. Example 5 75 parts of kaolin and 25 parts of aluminum hydroxide were dispersed using 0.5 part of sodium polyacrylate (solid content) and 0.5 part of soda birophosphate as dispersants to form a pigment slurry with a concentration of 68%. Prepared.

To this, 13 parts of a 20% concentration casein aqueous solution and 17 parts (solid content) of styrene-butadiene copolymer latex were added and mixed as an adhesive, and 0% ammonium oleate was added.
．． 5 parts were added to obtain a 53% coating solution. The viscosity of this coating liquid was 1500 cps (Brookfield viscometer, 60 rpm, 20"C) and pl 19.0.
Met. Gelling casting was performed using this coating liquid.

That is, the above-mentioned coating liquid was applied to base paper of 90 g/rf by a roll coater so that the dry weight was 25 g/rrf,
The coated layer was gelled by contacting with a 0.5% formic acid aqueous solution. The paper was passed through a press nip formed by a press roll with a diameter of 800 mm coated to a thickness of 15 mm and a cast drum with a diameter of 3,000 mm with a surface temperature of 108 °C at a casting speed of 60 m/min to form a gelled coating layer. was pressed onto a cast drum with a press roll pressure of 100 kg/cm, and after drying, it was peeled off with a take-off roll and the cast coated paper was wound up.

A gel cast finish was applied to the opposite side in the same manner again to obtain double-sided cast coated paper. In this case, the drum temperature was 90°C and the speed was 30 m/min. The double-sided cast-coated paper thus obtained was passed through a super calender in the same manner as in Example 4 to perform surface finishing. A polyamide resin roll was used as the elastic roll at this time. Table 1 shows the operating conditions and the quality evaluation results of double-sided cast coated paper obtained through continuous operation.

Example 6 14 double-sided cast sheets obtained in the same manner as in Example 5 were
Using a 5-stage super calender, linear pressure of 100! t
The paper was passed under conditions of cg/cta and a speed of 400 m/min to perform surface finishing. A polyurethane resin roll was used as the elastic roll at this time. In addition, the operational conditions and quality evaluation results of double-sided cast coated paper obtained through continuous operation are shown.
Shown in 1. Comparative Example 1 A single-sided cast coated paper was obtained in the same manner as in Example 1 at a drum rotation speed of 40 m/min. Cast finishing was performed on the opposite side again in the same manner to obtain double-sided cast-coated paper. Casting speed was 15 m/min. Note that soft calender finishing was not performed. The quality evaluation results of the obtained double-sided cast coated paper are shown in Table 1. Comparative Example 2 A double-sided cast coated paper was obtained in the same manner as in Example 2. The surface roughness after the break-in operation at this time was 23 μm. Table 1 shows the operating conditions in this case and the quality evaluation results of the double-sided cast l covering obtained through continuous operation. Comparative Example 3 A double-sided cast coated paper was obtained in the same manner as in Example 3. In this case, the surface temperature of the metal roll of the calender is 350℃.
It was. Table 1 shows the operating conditions and the quality evaluation results of the double-sided cast coated paper obtained through continuous operation. Additionally, the elastic rolls developed cracks during operation, making continuous operation impossible. The printing evaluation showed that the paper texture was poor.

Comparative Example 4 A double-sided cast coated paper was obtained in the same manner as in Example 1, except that the surface temperature of the metal roll of the soft calender during operation was 10°C. Table 1 shows the operating conditions and the quality evaluation results of the double-sided cast-coated paper obtained through continuous operation.

Comparative Example 5 A double-sided cast coated paper was obtained in the same manner as in Example 5. As the elastic roll of the super calender, a polyamide resin roll having a surface roughness of 23 μm after running-in was used. Table 1 shows the operating conditions in this case and the quality evaluation results of the double-sided cast coated paper obtained through continuous operation. Comparative Example 6 A double-sided cast coated paper was obtained in the same manner as in Example 2. An epoxy resin roll with a Shore D hardness of 70° was used as the first elastic roll of the soft calender. Table 1 shows the operating conditions in this case and the quality evaluation results of the double-sided cast coated paper obtained through continuous operation. Comparative Example 7 A double-sided cast coated paper was obtained in the same manner as in Example 1. The elastic roll of the soft calender has a Shore D hardness of 82.
@ cotton roll was used. Table 1 shows the operating conditions in this case and the quality evaluation results of the double-sided cast coated paper obtained through continuous operation.

Example 7 Pigments: 70 parts of kaolin, 30 parts of light calcium carbonate, 10 parts of oxidized starch, 16 parts (solid content) of styrene-butadiene copolymer latex (trade name: SN-307/manufactured by Sumitomo No?Tack ■), A coating liquid with a concentration of 60% was prepared which contained 0.4 parts of charcoal Mzirconium ammonium (as ZrOz) as a water resistance agent.

The obtained coating liquid was coated on both sides of a 45 g/a base paper with an on-machine blade coater so that the dry weight was 10 g/rrf per side, and then dried to form a cast coated paper with dry coating layers on both sides. Got paper.

On the other hand, as a coating liquid for casting finishing, 80 parts of kaolin,
20 parts of cubic calcium carbonate with an average particle size of 0.5 μm, 14 parts of casein (as an adhesive for 100 parts of pigment)
(solid content) and 8 parts (solid content) of acrylic acid/butadiene/methyl acrylate (ratio: 2/33/65) copolymer latex, 0.
5 parts, 0 zirconium ammonium carbonate as a water resistant agent
．． A coating liquid for cast coated paper was prepared at a concentration of 53%, consisting of 4 parts (as ZrO) and 1.0 part of ammonium stearate as a mold release agent. Apply this coating liquid to one side of the base paper at a dry weight of 15 g/r.
rr, and immediately rotate at a rotation speed of 40 m/
It was dried under pressure on a first heating drum with a mirror surface heated to a surface temperature of 93°C for 7 minutes, and then peeled off from the heating drum with a take-off roll (7 to obtain a cast coated paper. The coated paper to be cast is 10 mm in diameter.
00aus chrome plated metal roll and diameter 80
0 tm elastic roll, on-cast soft calender finishing machine with 2 nips, linear pressure 100 kg/c
The paper was passed under the conditions of m, and the surface was finished.Heating of the metal roll at this time was performed by an induction heating method. An epoxy resin roll was used as the elastic roll. Table 2 shows the quality evaluation results of the back-coated cast coated paper (single-sided cast coated paper) obtained under the operating conditions and continuous operation in this case.

Example 8 The same procedure as in Example 7 was carried out, except that a polyamide-imide resin roll was used as the elastic roll, the surface temperature of the metal roll was 250°C, the Shore D hardness was 96°, and the surface roughness after breaking-in was 4 mμ. Finished the surface of single-sided cast coated paper. Table 2 shows the operating conditions and the quality evaluation results of the single-sided cast coated paper obtained through continuous operation.

Example 9 75 parts of kaolin and 25 parts of aluminum hydroxide were dispersed using 0.5 part of sodium polyacrylate (solid content) and 0.5 part of sodium birophosphate as dispersants to form a pigment slurry with a concentration of 68%. Prepared. Add to this slurry 13 parts of a 20% casein aqueous solution and 1 part of styrene-butadiene copolymer latex as an adhesive.
7 parts (solid content) were added and mixed, and further 0.5 part of ammonium oleate was added to obtain a coating liquid with a concentration of 53%.

The viscosity of this coating liquid was 1500cpa (Brookfield viscometer, 5Qrpa+, 20''C) and the pH
9. It was 0.

Gel casting was performed using this coating liquid.

That is, the coating liquid used in Example 7 was coated on a base paper having a weight of 160 g/rrf using an off-blade coater to give a coating liquid of 25 g/nl on one side. The coated layer was coated with a roll coater so that the amount was 25 g/rrf, and the coated layer was gelled by contacting with a 0.5% formic acid aqueous solution. Diameter 80 coated with a thickness of 15 mm
The paper was passed through a press nip formed by a 0 m press roll and a 3000 m diameter cast drum with a surface temperature of 108 °C at a casting speed of 30 m/min, and the gelled coating layer was applied to the cast drum at a press roll pressure of 100 kg. /c@
After drying, it was peeled off using a take-off roll, and 14 pieces of the cast film with the back side coated were rolled up.

The cast coated paper thus obtained was placed in a 5-stage super calender at a linear pressure of 150 Kg/cra and a speed of 200 m/cm.
The paper was passed in minutes and the surface was finished. Polyamide resin was used for the elastic roll at this time. In addition, Table 2 shows the operating conditions and the quality evaluation results of the single-sided cast coated paper obtained through continuous operation.

Comparative Example 8 Single-sided cast finishing was carried out in the same manner as in Example 7 at a drum rotation speed of 40 m/min to obtain a cast-coated paper with the back side coated. Next, soft calender finishing was not performed. Table 2 shows the quality evaluation results of the single-sided cast iron coated in this way.

Comparative example 9 A cast coated paper coated on the back side was obtained in the same manner as in Example 7.

That is, the cast coated paper was coated with an on-machine blade coater at a dry weight of 10 g/I and on the back side at a dry weight of 10 g/I to obtain cast-coated paper Kawahara paper. The operating conditions in this case and the quality evaluation results of the back-coated cast coated paper obtained through continuous operation are shown in Table 2.

Comparative example 10 A cast coated paper coated on the back side was obtained in the same manner as in Example 7.

In this case, the surface roughness of the elastic roll after the break-in operation is 23
It was μm. Table 2 shows the operating conditions and the quality evaluation results of the back-coated cast coated paper obtained through continuous operation.

Comparative Example 1) A cast coated paper with a reverse side coating was obtained in the same manner as in Example 7.
In this case, the elastic roll was made of 80% cotton and 20% polyester. Table 2 shows the operating conditions and the quality evaluation results of the back-coated cast coated paper obtained through continuous operation.

"Effect" As is clear from the results in Tables 1 and 2, the double-sided cast-coated paper and the reverse-coated cast-coated paper obtained in the Examples according to the method of the present invention showed high performance on both sides even in continuous operation. It was a cast coated paper with extremely excellent smoothness.

Claims (4)

[Claims] (1) Cast coated paper that has a cast coating layer mainly composed of pigments and adhesives on one side of the base paper, and a coating layer mainly composed of pigments and adhesives or a cast coating layer on the back side In the finishing method, the cast coated paper is heated to a surface temperature of 1
Cast coated paper, characterized in that the paper is passed through a calender consisting of a metal roll at 5 to 300°C and a synthetic resin roll with a Shore D hardness of 75° or more and a surface roughness Rmax defined by JISB0651 that satisfies the following formula: Finishing method. Rmax<15+0.1D-0.02T In the formula, each symbol is as follows. Rmax: Surface roughness of elastic roll after running-in (μm
) D: Shore D hardness of elastic roll (°) T: Surface temperature of metal roll during operation (°C) (Temperature range: 15-300°C) (2) A metal roll with a surface temperature of 20 to 250°C, a Shore D hardness of 77° or more, a surface roughness Rmax defined by JISB0651 that satisfies the following formula, and the roll material is epoxy resin, polyamide resin, or polyimide. resin,
The method for finishing cast coated paper according to claim 1, wherein the paper is passed through a calender comprising a synthetic resin roll made of one or more of polyamide-imide resin and polyurethane resin. Rmax<13+0.1D-0.02T In the formula, each symbol is as follows. Rmax: Surface roughness of elastic roll after running-in (μm
) D: Shore D hardness of elastic roll (°) T: Surface temperature of metal roll during operation (°C) (Temperature range: 20-250°C) (3) In a method for finishing cast coated paper, in which one side of the base paper has a cast coating layer mainly composed of pigments and adhesives, and the back side has a coating layer mainly composed of pigments and adhesives. The method for finishing cast coated paper according to claim 1 or 2, wherein the coating amount of the back coating layer is 5 to 30 g/m^2. (4) The method for finishing cast coated paper according to any one of claims (1) to (3), wherein the metal roll of the calender is heated by an induction heating method.