JP2010111969A - Surface-treating agent for coated base paper - Google Patents

Abstract

The present invention provides a surface treatment agent for coated base paper, and a coated paper using the same and a method for producing the coated paper, from which a light and highly glossy coated base paper can be obtained.
A surface treatment agent for coated base paper, comprising (A) a nonionic water-soluble polymer compound selected from polyvinyl alcohol and cellulose derivatives, and (B) a crosslinking agent of component (A). A coated base paper obtained by treating 0.01 to 2.0 g / m @ 2 of the surface treatment agent for coated base paper with a dry weight per side on at least one side of a paper mainly composed of pulp.
[Selection figure] None

Description

  The present invention relates to a surface treatment agent for coated base paper, a coated base paper using the same, and coated paper.

  In recent years, there has been an increasing demand for weight reduction of printing paper in order to reduce transportation and mail costs. However, simply reducing the weight, that is, reducing the basis weight of the printing paper is not preferable because the thickness of the paper is reduced and the volume of the booklet is impaired. The reduction in weight required means that the paper thickness is reduced while the high glossiness of the coated paper is maintained while the paper thickness is not reduced. On the other hand, with the progress of visualization and colorization of printed materials, the demand for coated paper for printing with a smooth coating layer on the paper surface as an ink-receiving layer is increasing year by year as compared to uncoated printing paper. The coating layer mainly composed of inorganic pigments such as calcium carbonate and kaolin has a higher specific gravity than the base paper coated with pulp as the main raw material. There is a need to reduce it. However, when the density of the base paper is reduced, the number of pores increases, so that the permeability of the paint into the base paper increases during coating, and it becomes difficult to uniformly coat the base paper surface with a low coating amount. Therefore, if the base paper is calendered before coating in order to reduce the pore volume of the base paper, the penetrability of the paint into the base paper is reduced, but the paper thickness is reduced, so low density paper cannot be obtained. In this way, to reduce the weight of coated paper, even if a light and bulky base paper is used, simply applying a paint mainly composed of a high specific gravity inorganic pigment increases the coating amount due to the penetration of the paint. Thus, it is difficult to achieve light weight while maintaining the high gloss of the coated paper.

Further, as a method of suppressing the penetration of the coating material into the base paper, a method of performing a sizing process on the base paper in order to reduce the wettability between the base paper and water as a solvent of the coating material can be considered. For example, Patent Document 1 describes a treating agent containing cationic polyacrylamide and an anionic copolymer containing a monomer having a hydrophobic substituent. In addition, a method of applying an aqueous solution containing a swellable mica and a binder in order to suppress the penetration of a release agent such as silicone into a release paper base is disclosed (see Patent Document 2). In addition, it has been proposed that a specific amount of swellable mica can be applied to the surface of a light bulky base paper for printing to effectively suppress the penetration of the hydrophilic paint (see Patent Document 3). On the other hand, the penetration inhibitor made of carboxymethyl cellulose sodium salt having specific physical properties suppresses the penetration of the hydrophilic paint into the inside of the support having a hydrophilic and porous surface layer like a bulky paper, and the application is small A coating layer effective in amount has been proposed (see Patent Document 4). In addition, a method has been proposed in which hydrophilic paint is applied to paper on which a dry film layer of an organic polymer gel has been previously formed, thereby suppressing the penetration of the hydrophilic paint into the coated base paper (Patent Document 5). reference).
Japanese Patent Laid-Open No. 11-012981 JP-A-6-200500 JP 2005-89871 A Japanese Patent Application Laid-Open No. 2004-300624 JP 2007-107171 A

  However, as in Patent Document 1, even if such a treatment is performed on a low density base paper having a large amount of pores, the effect is small. The release paper coating used in Patent Document 2 is hydrophobic because it is mainly composed of toluene and silicone, and is a hydrophilic printing coating in which pigments such as calcium carbonate and kaolin and a binder are dispersed in water at a high concentration. Since the physical properties of paints differ significantly, they cannot solve the problem of general coated paper. Further, Patent Document 3 has a drawback that the swellable mica is very expensive and cannot be used for producing general-purpose printing paper. Therefore, it has been very difficult to effectively suppress the penetration of the coating material on the surface of the lightweight base paper for printing and to efficiently form the coating layer of the coating layer by using a relatively inexpensive material. Moreover, in patent document 4, although the penetration | permeation of a coating material is suppressed by the processing agent which consists of carboxymethylcellulose sodium salt which has a specific physical property, effectiveness is recognized by ventilation resistance, there are few effects, such as improvement of glossiness Met. Patent Document 5 describes a method of applying a water-soluble organic polymer after internally adding a polyvalent metal ion salt to a base paper or after applying a polyvalent metal ion salt to a base paper. However, since the polyvalent metal ion salt is present throughout the paper, it is extremely inefficient from the viewpoint of contact with the water-soluble organic polymer. Especially, the water-soluble organic ion salt is applied after the polyvalent metal ion salt is applied to the base paper. The method of applying a polymer increases the number of steps of application and drying, and is not an industrially advantageous method. Moreover, in Patent Document 5, since the amount of polyvalent metal ion salt used is very large (for example, 100 to 222% with respect to the water-soluble organic polymer in the examples), it becomes difficult to reuse white water during papermaking. There is a concern that the surface strength of the coated paper is lowered.

  The subject of this invention is providing the surface treating agent for coating base paper from which the light and highly glossy coating base paper is obtained.

  The present invention relates to (A) a nonionic water-soluble polymer compound selected from polyvinyl alcohol and cellulose derivatives [hereinafter referred to as (A) component], and (B) a crosslinking agent (A) component [hereinafter referred to as (B). The surface treatment agent for coated base paper.

In addition, the present invention provides a coating treatment in which the surface treatment agent for coated base paper of the present invention is treated at a dry weight of 0.01 to 2.0 g / m ^{2 on} one side on at least one side of a paper mainly composed of pulp. Concerning the base paper.

In the present invention, the coating base paper of the present invention is provided with a coating layer of a paint mainly composed of a pigment and a binder on the surface treated with the surface treatment agent for coating base paper. It is related with the coated paper which is 5 g / cm ³ or less.

Further, the present invention is a process for obtaining a coated base paper by treating the surface treating agent composition containing the surface treating agent for coated base paper of the present invention and water on at least one side of a paper mainly composed of pulp. (I),
A coating layer of a paint mainly composed of a pigment and a binder, which is different from the surface treatment agent composition, is provided on the treated surface of the coated base paper obtained in the step (I) by the surface treatment agent composition. Providing step (II);
And a method for producing a coated paper having a density of 1.5 g / cm ³ or less.

  When the surface treatment agent of the present invention is applied to the base paper surface and dried, the reason why the above problem is solved is not clear, but the nonionic water-soluble polymer compound (A) is the component (B). When a cross-linked product is formed with a cross-linking agent and the cross-linked product is present on the surface of the base paper, when a paint mainly composed of a pigment and a binder is applied, the paint dispersion is partially destroyed, resulting in It is presumed that the paint is agglomerated and the penetration of the paint mainly composed of inorganic pigment into the paper is suppressed.

  In addition, since a cross-linked product of a highly hydrophilic nonionic water-soluble polymer compound exists on the paper surface, when a paint mainly composed of a pigment and a binder is applied, moisture in the paint is instantaneously It is presumed that the absorption of the paint with the inorganic pigment as a main component is suppressed due to the absorption, and the penetration of the paint mainly composed of an inorganic pigment into the paper is suppressed.

  In addition, when a cross-linked product of a highly hydrophilic nonionic water-soluble polymer compound is applied to the paper surface, it fills the pores of the paper having a porous surface layer portion so that the paint inside the base paper is filled. It is also estimated that the penetration is suppressed.

  According to the present invention, it is possible to suppress the penetration of the paint into the base paper, and an effective coating layer can be obtained with a small coating amount using a current paper machine or coating machine, which is lightweight, high in weight. A surface treating agent for coated base paper that can efficiently produce glossy coated paper is obtained. The coated paper produced from the coated base paper treated with the surface treating agent for coated base paper of the present invention is lightweight and has high gloss.

  In addition, when the same amount of coating layer is applied, a highly glossy coated paper can be obtained, so that the calender linear pressure can be lowered in the calendering step after applying the coating layer. In addition, pulp, pigments, dyes, etc. of coated paper can be reduced, leading to resource saving and energy saving as well as density reduction.

[Component (A)]
The component (A) of the present invention is a nonionic water-soluble polymer compound selected from polyvinyl alcohol and cellulose derivatives. Regarding the component (A), “water-soluble” means that when 1 part by weight of the target polymer compound is dissolved in 99 parts by weight of water at 25 ° C., the solubility is 50% by weight or more. The solubility is calculated from the solid content in the filtrate by filtering the aqueous solution with a filter paper (No. 2). The component (A) preferably has a solubility of 80% by weight or more.

The component (A) preferably contains a water-soluble nonionic group selected from units such as vinyl alcohol, modified cellulose, and ethylene oxide. The component (A) has a high water-solubility selected from the following: Examples include molecular compounds.
(A1) Polyvinyl alcohol (A2) Cellulose derivative in which methyl group is introduced into cellulose polymer (A3) Cellulose derivative in which hydroxyethyl group is introduced into cellulose polymer

  Among these nonionic group-containing polymer compounds, water-soluble compounds selected from polyvinyl alcohol, methyl cellulose, and hydroxyethyl cellulose are preferable. The saponification degree of polyvinyl alcohol is preferably 80 to 100%, more preferably 85 to 100%, from the viewpoint of improving the glossiness.

  Although the molecular weight of (A) component is not limited, It is preferable that it is a molecular weight which can be bridge | crosslinked by (B) component. For example, in (A1) polyvinyl alcohol, the weight average molecular weight is preferably 15,000 to 150,000, and more preferably 17,000 to 120,000. In the case of methylcellulose, the weight average molecular weight is preferably 100,000 to 2,000,000, more preferably 150,000 to 1,500,000.

[(B) component]
(B) component of this invention is a crosslinking agent of (A) component, A polyfunctional compound is preferable and the crosslinking agent chosen from a polyfunctional epoxy compound, a polyfunctional carboxy compound, and a boron compound is used preferably.

The polyfunctional epoxy compound is preferably a polyvalent epoxy compound, such as polyethylene glycol polyglycidyl ether [Denacol EX-512 (epoxy equivalent 173, functional group number 4), Denacol EX-810 (epoxy equivalent 112, functional group number 2), Nagase Sangyo Co., Ltd.], polyglycerin polyglycidyl ether [SR-4GL (epoxy equivalent 175, functional group number 2 or more), Sakamoto Pharmaceutical Co., Ltd.]. The polyfunctional carboxy compound is preferably a polyvalent carboxylic acid, and examples thereof include maleic acid, fumaric acid, phthalic acid, adipic acid, itaconic acid, trimellitic acid, and butanetetracarboxylic acid. Examples of the boron compound include borax (Na ₂ B ₄ O ₇ .10H ₂ O). Of these, borax, butanetetracarboxylic acid, polyglycerol polyglycidyl ether, and polyethylene glycol polyglycidyl ether are preferred.

<Surface treatment agent for coated paper>
In the surface treatment agent for coated base paper of the present invention, the weight ratio of the component (A) to the component (B) is (A) / (B) = 100 / 0.0005 to 100/15, more preferably 100 / 0.001. It is preferably ~ 100/10. In this weight ratio, when the ratio of the component (B) to 100 in the component (A) is 0.0005 or more, the degree of crosslinking of the component (A) obtained becomes appropriate, and the crosslinked product of the component (A) When applied to paper, the ratio of staying on the paper surface is improved, and it is difficult to penetrate into the paper. For this reason, when a paint was applied, a part of the paint was agglomerated, and the cross-linked product of the component (A) was present on the paper surface, so that the paint mainly composed of a pigment and a binder was applied. At this time, the moisture in the paint is instantaneously absorbed to make the paint become highly viscous and non-flowable, or when the cross-linked product of component (A) is applied to the paper surface, the fineness of the paper having a porous surface layer portion is reduced. By filling the hole, the effect of suppressing the penetration of the paint into the base paper is sufficiently exhibited. When the ratio of the component (B) to the component (A) is 100 or less in the weight ratio, when the crosslinked product of the component (A) is applied to paper, In this case, the ability to absorb moisture in the paint does not decrease, the paint becomes highly viscous, and the effect of non-flowing can be maintained. The surface treatment agent for coated base paper of the present invention of the present invention can be used as a primer for a coating liquid (paint) in coating production.

  Further, the equivalent ratio of the component (A) to the component (B) is preferably 100 / 0.0005 to 100/30, more preferably 100 / 0.001 to 100/20 in (A) / (B).

  The suitable aspect of the surface treating agent for coated base paper of this invention is a liquid composition containing (A) component, (B) component, and water, and (A) component in this liquid composition The content is preferably 0.1 to 30% by weight, more preferably 0.2 to 20% by weight, and particularly preferably 0.3 to 10% by weight. The component (B) is added in the above ratio to the component (A) within this range. It is preferable to contain. The liquid composition is preferably an aqueous solution or an aqueous dispersion.

  The method for treating the surface treatment agent for coated base paper of the present invention on the surface of the coated base paper is not particularly limited, and is applied to the surface of the coated base paper prepared in advance.

The paper which is the target of the surface treatment agent for coated base paper of the present invention is one having pulp as a main raw material, preferably having a density of 0.30 to 1.00 g / cm ³ , more preferably 0.00. 35 to 0.85 g / cm ³ . When the density is 0.30 g / cm ³ or more, a decrease in paper strength can be suppressed, so that the frequency of sheet cutting during coating is reduced and stable operation is possible. Moreover, since the surface treatment agent for coated base paper of the present invention is appropriately processed on the surface of the base paper, the paper having a density of 1.00 g / cm ³ or less has an appropriate air resistance and blister resistance during offset printing. And the use as a coated paper for printing is not restricted.

  As the pulp used for the base paper, any pulp made of wood or herbaceous fibers, which are vegetable fibers, can be used. That is, bleached chemical pulp (NBKP, LBKP, etc.), mechanical pulp (TMP, CTMP, GP, RGP, etc. and bleached pulp thereof), high yield pulp (SCP, CGP, etc. and bleached pulp thereof) and Recovered pulp such as waste paper pulp, deinked waste paper pulp (DIP), and bleached pulp (BDIP) can be used.

  Moreover, you may add auxiliary chemicals for paper manufacture, such as a filler, a paper strength enhancer, a sizing agent, a yield improver, a drainage improver, and a bulkiness agent, as needed. Examples of sizing agents include alkyl ketene dimer sizing agents, alkenyl succinic anhydride sizing agents, and neutral rosin sizing agents. Examples of the filler include calcium carbonate.

The coating amount of the surface treatment agent for coated base paper in the present invention is 0.01 to 3.0 g / m ² as a dry weight (preferably the total dry weight of the component (A) and the component (B)) per one side of the base paper. Is more preferable, 0.02 to 2.0 g / m ² , still more preferably 0.03 to 1.0 g / m ² . When it is 0.01 g / m ² or more, the effect of suppressing the penetration of paint is exhibited, and when it is 3.0 g / m ² or less, the total coating amount on both sides is 6 g / m ² or less, thereby reducing the weight of the paper. .

  The treatment method for the surface treatment agent can be appropriately selected from known methods. In particular, a two-roll size press, a blade metalling size press, a rod metalling size press, a curtain coater, a die coater, a gravure coater, and a kiss coater. A bar coater, an air knife coater, a blade coater, a roll coater, a pound type size press, a gate roll coater, a spray coater, a shim sizer and the like are preferable.

  The method for applying the surface treatment agent to the paper surface is not limited, but as a general method, a solution or dispersion containing the components (A) and (B) according to the present invention is used. As the solvent or dispersion medium in this case, water or an organic solvent is used, and water is particularly desirable.

  In the case of a solution or dispersion, the component (A) of the powder or mass obtained by copolymerization according to the present invention has an average particle size of the copolymer of 1 mm or less, preferably 300 μm or less, more preferably by a method such as grinding. Is an average particle diameter of 50 μm or less, mixed with a solvent or a dispersion medium, and component (B) is added to this to be used as a solution or dispersion. When the average particle diameter of the component (A) is 1 mm or less, dissolution and dispersion are quick and preferable. When the component (A) according to the present invention is obtained as a solution or dispersion, it is used as it is or after being diluted with the component (B).

In this invention, it is preferable to process the coating base paper processed with the surface treating agent for coating base paper on the conditions which (A) component bridge | crosslinks. Examples of the conditions for crosslinking the component (A) include drying at 80 to 140 ° C. for 1 to 600 seconds. For drying, a steam heater, hot air heater, infrared heater, gas heater, cylinder dryer, or the like is used. According to the present invention, the surface treatment agent for coated base paper of the present invention is applied to at least one side of a paper mainly composed of pulp, and the coating amount of the surface treatment agent for coated base paper is dry weight per side. And a step of drying under the condition that the component (A) is crosslinked so as to be 0.01 to 3.0 g / m ² , a method for producing a coated base paper is provided.

The present invention relates to a surface treatment agent for coated base paper containing a specific component (A) and component (B), and further coating the paper surface with the component (A) and component (B). The present invention relates to a coated paper in which a coating layer of a paint mainly composed of a pigment and an adhesive is provided on a base paper. That is, the coating surface of the coated base paper according to the present invention is provided with a coating layer of a paint mainly composed of a pigment and a binder on the treated surface of the present invention, and the density is 1.5 g / cm ³ or less. It relates to a certain coated paper. Such a coated paper is, for example, a coated base paper obtained by treating the surface treating agent composition containing the surface treating agent for coated base paper of the present invention and water on at least one side of a paper mainly composed of pulp. The surface of the coated base paper obtained in step (I) is treated with the surface treatment agent composition, and the pigment and the binder are different from the surface treatment agent composition. And a step (II) of providing a coating layer of the paint.

  As a pigment and an adhesive used as a paint for forming a coating layer, those used for ordinary coated paper can be used. Examples of the pigment include inorganics such as kaolin, clay, calcium carbonate, and titanium dioxide. Organic pigments such as pigments and plastic pigments can be used. Various adhesives such as styrene / butadiene, styrene / acrylic, ethylene / vinyl acetate, butadiene / methyl methacrylate, and vinyl acetate / butyl acrylate, which are conventionally used for coated paper, are also available. Polymer latex, oxidized starch, positive starch, phosphate esterified starch, urea phosphate esterified starch, etherified starch such as hydroxyethyl etherified starch, starch such as dextrin, and the like can be used. These adhesives are used in the range of about 5 to 50% by weight, more preferably about 10 to 30% by weight per 100% by weight of the pigment. If necessary, various commonly used auxiliaries such as a dispersant, a thickener, a water retention agent, an antifoaming agent, and a water resistant agent are used.

  Paint coating methods include blade coater, air knife coater, gate roll coater, blade metering size press, rod metering size press, curtain coater, die coater, blade coater, roll coater, pound type size press, gate roll A known method such as a coater can be used.

The thickness of the coating layer is not particularly limited and is set according to the application and quality of the coated paper. From the viewpoint of obtaining high gloss paper, the coating amount of coating liquid (paint) (solid content conversion) is preferably 6 g / m ² or more per one surface, more preferably 6 to 25 g / m ^2, more preferably from 7~20g / m ^2.

  The coated base paper on which the coating layer is formed is preferably dried. As a drying method, a normal method such as a steam heater, a hot air heater, an infrared heater, a gas heater, or a cylinder dryer is used. Further, smoothing processing such as super calendar and soft calendar is performed as necessary.

In order to further exhibit the effect of the present invention, the density of the coated paper is preferably from 1.5 g / cm ³ or less, more preferably 0.40~1.40g / cm ^3.

  Paper manufactured from the base paper treated with the surface treatment agent for coated base paper of the present invention is high-quality printing paper, medium-quality printing paper, newspaper printing paper, gravure printing paper, PPC paper, laser printer paper, foam paper, paperboard base paper Can be used for It is also used for coated base papers such as art paper, cast coated paper, medium coated paper, high quality coated paper, cast coated paper, A0 art paper, A1 art paper, A2 coated paper, A3 coated paper, thermal transfer paper, etc. be able to. Among these, it can be effectively used for various types of coated paper for which surface gloss improvement is required.

  Hereinafter, “parts” and “%” indicating the blending amounts all indicate “parts by weight of solids” and “% by weight of solids”.

[Component (A)]
The following water-soluble polymer compounds were used as the component (A).
PVA-117: polyvinyl alcohol, saponification degree 98-99%, polymerization degree 1700, manufactured by Kuraray Co., Ltd. PVA-210: polyvinyl alcohol, saponification degree 87-89%, polymerization degree 1000, manufactured by Kuraray Co., Ltd. KL-05: polyvinyl alcohol, saponification degree 78.5-82%, polymerization degree 500, manufactured by Nippon Synthetic Chemical Co., Ltd. GH-17: polyvinyl alcohol, saponification degree 86.5-89%, polymerization degree 1700 , Manufactured by Nippon Synthetic Chemical Co., Ltd. MC: methyl cellulose, viscosity (2%, 20 ° C.) 3500-5600 mPa · s, manufactured by Wako Pure Chemical Industries, Ltd. HEC: hydroxyethyl cellulose, SZ-25F, Sumitomo Seika Co., Ltd. ) Made

[(B) component]
The following compounds were used as the component (B).
-Borax: Reagent, manufactured by Wako Pure Chemical Industries, Ltd.-BTCA: Butanetetracarboxylic acid, reagent, manufactured by Wako Pure Chemical Industries, Ltd.-Denacol EX-512: Polyglycerol polyglycidyl ether, manufactured by Nagase Sangyo Co., Ltd.・ Denacol EX-810: Polyglycerol polyglycidyl ether, manufactured by Nagase Sangyo Co., Ltd.

[Comparative compound]
The following compounds were used as comparative compounds.
Ace A: oxidized starch, manufactured by Oji Constarch Co., Ltd. WS-4020: polyamide epichlorohydrin resin, 25% effective content, manufactured by Seiko PMC Co., Ltd.

[Surface treatment agent for coated base paper]
Using the component (A), the component (B) and the comparative compound as the surface treating agent for coated base paper in the composition shown in Table 1, coated paper was produced as follows. In Table 1, compounds not corresponding to the component (A) are also shown in the column for the component (A) for convenience.

[Production method of base paper]
(1) Base paper <pulp raw material>
As a pulp raw material, virgin pulp was used in which LBKP (hardwood bleached pulp) was disaggregated and beaten with a beater at 25 ° C. to obtain a 2.2 wt% LBKP slurry. The Canadian standard freeness (JIS P 8121) of this product was 450 ml.

<Paper making method>
The virgin pulp slurry was weighed so that the pulp basis weight of the pulp sheet after paper making would be 80 g / m ² ± 1 g / m ^2, and paper was made with 80 mesh wire (area 625 cm ² ) with a square tappi paper machine. A sheet was obtained. The sheet after paper making was pressed with a press at 3.5 kg / cm ² for 5 minutes and dried at 105 ° C. for 2 minutes using a mirror dryer. The dried pulp sheet was conditioned at 23 ° C. and a humidity of 50% for 1 day to obtain a base paper for surface treatment. The bulk density of the base paper was 0.574 g / cm ³ . However, in Comparative Examples 2, 3, and 4, in the above, 0.032 g (Comparative Examples 2 and 4) and 0.32 g (Comparative Example 3) of borax as an internal additive to 80 g of pulp were added to the virgin pulp slurry. Thus, a base paper (pulp basis weight of 80 g / m ² ± 1 g / m ² ) was obtained. The base paper bulk density of Comparative Examples 2, 3, and 4 was 0.574 g / cm ³ .

[Treatment method with surface treatment agent for coated base paper]
A casting film of 50 g / m ² was formed on a glass plate using an aqueous solution containing the components shown in Table 1 at a predetermined concentration as a surface treatment agent for coated base paper using a wire coater. Next, the base paper (width 12.5 cm × length 25 cm) is placed on the casting film, covered with one piece of 100 g / m ² filter paper, and a roll (diameter 200 mm, width 200 mm, linear pressure 230 g / cm) is rolled and coated. The surface treatment agent for engineering base paper was transferred from the glass plate to the base paper surface. Next, it was dried at 105 ° C. for 2 minutes using a mirror dryer (Example 5 was further dried at 140 ° C. for 2 minutes). These series of operations were operated promptly without any intermission. The dried pulp sheet was conditioned at 23 ° C. and a humidity of 50% for 1 day to obtain a base paper for coating. In addition, aqueous solution density | concentration etc. adjusted so that processing amount (solid content conversion) might become the numerical value in a table | surface. In Comparative Example 4, a surface treatment agent was treated on a base paper in which borax was added in advance, and the surface-treated component (A) was 0.69 g / m ^2. When all are taken in the base paper, the amount of component (B) added is 0.032 g / m ² .

[Production method of coated paper]
On one side of the coating base paper (surface-treated paper) obtained above, a paint is applied to a blade-type coating machine (flexible trailing blade coater, coating speed 140 m / min, coating pressure 0.5-1. The coating was carried out at 5 kg / cm ² (manufactured by Kumagai Riki Kogyo Co., Ltd.) and dried using a mirror drier for 20 seconds at 105 ° C.

  Here, 50 g of calcium carbonate (FMT97, manufactured by Phimatech Co., Ltd.) and 50 g of fine kaolin (Amazon Plus, manufactured by Kadem Co., Ltd.) are blended, and polyacrylic acid soda (Poise 535M, Kao Corporation) is used as a dispersant. )) 0.2 g and 0.2 g of 2N caustic soda were added and dispersed, and an SBR latex (LX-430, acrylic acid-modified SBR latex for papermaking, manufactured by Nippon Zeon Co., Ltd.) was added to 100 g of pigment as an adhesive. ) 11 g and modified starch (phosphate-modified starch, manufactured by Oji Constarch Co., Ltd.) 3.5 g.

  Further, a coated paper is obtained by performing a 2-nip treatment with a linear pressure of 200 kg / cm (pressure 49 MPa), a processing speed of 10 m / min, a roll temperature of 50 ° C., using a test super calendar (manufactured by Kumagaya Riki Kogyo Co., Ltd.). It was.

[Method for evaluating coated paper]
<Amount of surface treatment agent for coated paper>
The coated base paper (surface-treated paper) obtained by the treatment with the surface treatment agent for coated base paper and the base paper before the surface treatment are each conditioned at 23 ° C. and 50% humidity for one day, and the difference is sampled. The amount of treatment (g / m ² ) was calculated from the value divided by the area (width 12.5 cm × length 25 cm) (average value of the number of measured sheets 3). For those not subjected to the treatment with the surface treatment agent for coated base paper, the treatment amount was set to 0 g / m ² .

<Amount of paint applied>
A sample obtained by cutting a coated paper obtained in the manufacture of coated paper into a width of 12.0 cm and a length of 24 cm, and a coated base paper (surface-treated paper) obtained by treatment with a surface treatment agent for coated base paper (width) 12.5 cm × 25 cm in length) each for 1 day under the conditions of 23 ° C. and 50% humidity, and after calculating the basis weight of each, (basis weight of coated paper−basis weight of surface-treated paper) The coating amount (g / m ² ) was calculated from the value (average value of the number of measured sheets 3).

<Glossiness of blank paper>
Using a gloss meter (GMX-203 type, 75 ° type, manufactured by Murakami Color Research Laboratory Co., Ltd.) according to JIS P8142, the white paper glossiness of the coated surface was measured and the average value was obtained (number of measurement points: 6 / 1 sheet, 3 sheets measured, average value of 18 points). The higher the blank paper glossiness, the higher the glossiness, and the difference of 1% (1 point) in the blank paper glossiness is sufficiently recognized as a significant difference.

<Bulk density>
The tightness was measured according to JIS P8118 to obtain the bulk density (average value of the number of measured sheets 3). The smaller the bulk density, the lighter the weight, and the difference of 0.02 in the bulk density is sufficiently recognized as a significant difference.

  From Table 1, Examples 1 to 9 in which hand-treated paper was treated with the surface treatment agent for coated base paper of the present invention were not subjected to surface treatment or were based on a surface treatment agent for coated base paper different from the present invention. It turns out that very high glossiness is shown compared with comparative examples 1-8 which processed.

  Further, from Example 4 and Comparative Examples 1, 2, 3, 5 and the like, the coating composition of the present invention was compared with the case where the component (A) alone, the component (B) alone, or both (A) and (B) were not treated. It became clear that the example using the surface treating agent for the engineered paper gives a remarkably high gloss. Further, it can be seen from Comparative Example 4 that a sufficient effect cannot be obtained even when the component (B) is added and the component (A) is applied. In addition, even when compared with Comparative Examples 6 to 8 in which the agent used for the surface treatment of paper has been conventionally treated, the example using the surface treatment agent for coated base paper of the present invention has a remarkably high gloss. It became clear to give.

  When the glossiness equivalent to that of the conventional surface treatment agent is sufficient, the surface treatment agent for coated base paper of the present invention can remarkably reduce the coating amount of the coating material. The amount of work can be significantly reduced. As a result, the bulk density of the coated paper can be reduced and the weight can be reduced.

  Thus, when the surface treatment agent is applied to the base paper, it is clear that the glossiness of the surface treatment agent for coated base paper of the present invention is improved as compared with the existing technology, that is, the comparative example. When the coating amount of the pigment-containing paint and the calendar conditions are the same, since the penetration of the paint in the examples is suppressed, there is an effective coating layer that contributes to an improvement in gloss compared to the comparative example. It seems to be because it is increasing.

Claims (6)

  (A) a nonionic water-soluble polymer compound selected from polyvinyl alcohol and cellulose derivatives (hereinafter referred to as (A) component), and (B) a crosslinking agent for component (A) (hereinafter referred to as (B) component); A surface treatment agent for coated base paper containing   The surface treatment agent for coated base paper according to claim 1, wherein the component (B) is a cross-linking agent selected from a polyfunctional epoxy compound, a polyfunctional carboxy compound, and a boron compound.   The surface treatment agent for coating base paper of Claim 1 or 2 whose weight ratio of (A) component and (B) component is (A) / (B) = 100 / 0.005-100 / 10. The surface treatment agent for coated base paper according to any one of claims 1 to 3 is treated at a dry weight of 0.01 to 2.0 g / m ² per side on at least one side of a paper whose main raw material is pulp. Coated base paper. A density of 1.5 g / cm ³ , wherein a coating layer of a paint mainly composed of a pigment and a binder is provided on the treated surface of the coated base paper according to claim 4 with the surface treatment agent for coated base paper. The coated paper that is below. A surface treatment agent composition containing the surface treatment agent for coated base paper according to any one of claims 1 to 3 and water is applied to at least one side of a paper whose main raw material is pulp, and a coated base paper is obtained. Obtaining step (I);
A coating layer of a paint mainly composed of a pigment and a binder, which is different from the surface treatment agent composition, is provided on the treated surface of the coated base paper obtained in the step (I) by the surface treatment agent composition. Providing step (II);
A method for producing a coated paper having a density of 1.5 g / cm ³ or less.