JP2939971B2 - Printing paper with improved water absorption, newspaper printing paper, and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printing paper having improved water absorption and the like, and more particularly to newsprint and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the printing technology has been offset printing,
Significant progress has been made in color printing, high-speed mass printing, and automation. Along with this, for printing paper,
Improvements in various physical properties are required from the viewpoint of workability and printability.

[0003] In particular, newsprint paper is generally a paper mainly composed of mechanical pulp or deinked pulp (hereinafter abbreviated as DIP), and is classified into middle and lower grade paper. In newspaper printing, a specified number of copies must be reliably printed within a specified time in a specified time zone, and the quality of paper is required to be stricter than that of general printing paper. In this regard, newsprint paper is a special type of paper, and has its own classification in terms of paper classification. Recent newspaper printing papers are required to be lightweight and have a high DIP blending. While overcoming the disadvantages of these points,
Various improvements need to be made. In that sense, the improvement of newsprint paper is the improvement of general printing paper.
It is a very different dimension.

In recent years, with respect to newspaper printing, computer systems for newspaper printing have recently been required in view of various demands (for example, a demand for high-speed printing, a demand for color space, a demand for various kinds of printing, and a demand for automation). Coupled with the time of introduction,
The transition from letterpress printing to offset printing is proceeding rapidly.

The spread of offset printing requires newsprint paper to have a quality different from that of newsprint paper for letterpress printing. For example, the qualities are (1) wet strength and no drainage, (2) moderate water absorption, and (3) no paper dust. Among the required qualities, in particular, retention of water absorption, in other words, control of water absorption is an important issue.

In general printing paper, the water absorption is controlled by, for example, adding a chemical such as a sizing agent internally or externally to impart sizing properties to the printing paper. Internal addition is a method of adding chemicals to the pulp slurry at the so-called wet end, so that the chemicals are contained inside the paper at the same time as paper making. External addition is a size press or gate roll coater after paper making. This is a method in which a chemical is applied to the paper surface using a coating machine represented by, for example.

[0007] Sizing agents for internal addition include reinforced rosin sizing agents, emulsion sizing agents and synthetic sizing agents in the case of acidic papermaking, and alkyl ketene dimer (AKD) and alkenyl succinic anhydride in the case of neutral papermaking. Things (AS
A) is known. JP-A-60-88196 and JP-A-4-363301 disclose a sizing agent comprising a cationized starch and an alkyl ketene dimer.

The sizing agent for external addition (also referred to as a surface sizing agent) includes anionic polymers such as styrene / maleic acid copolymer and styrene / acrylic acid copolymer; rosin, tall oil, and the like. Anionic low molecular compounds such as saponified alkyd resins such as phthalic acid and saponified petroleum resins and rosins; and cationic polymers such as styrene-based polymers and isocyanate-based polymers are known.

On the other hand, the control of water absorption in newsprint paper includes, for example, (a) internal addition of chemicals such as a sizing agent and a water-proofing agent, (b) change of raw material composition, and (c) change of papermaking conditions. The current situation is to deal with it.

On the other hand, recent major trends in newsprint paper itself include flows such as weight reduction and high blending of DIP.

Regarding the weight reduction of newsprint paper, for example, in 1989, 96% of newsprint paper having a basis weight of 46 g / m ² was used.
In 1993, newspaper printing paper with a basis weight of 43 g / m ² accounted for about 80%. Such weight reduction causes problems such as a decrease in opacity of newspaper printing paper and a decrease in paper strength. On the other hand, an increase in the amount of DIP causes an increase in various components (fine fibers, fillers, pigments, etc.) derived from DIP. The increase in these components
It causes problems such as paper falling, paper strength drop,
These problems also become more serious as the proportion of DIP increases. These newsprint trends are:
In particular, it is a major negative factor in terms of surface strength.

[0012] Accordingly, newsprint paper for offset printing needs to be improved in surface strength while overcoming the negative effects of weight reduction and high blending of DIP in addition to the improvement in water absorption. It is required more remarkably stringent quality improvements in, for example, improved newsprint less than a basis weight 46 g / m ² is becoming very difficult task than improving a basis weight of 46 g / m ² or more newsprint ing.

[0013] The improvement of the surface strength of newsprint paper is roughly classified into two measures: non-coating measures and coating measures. Non-coating measures include changing the raw material mix, changing the papermaking conditions, and increasing the strength of the paper strength agent.However, this alone can no longer meet the strict quality requirements for newsprint paper for offset printing. It is a difficult situation. On the other hand, countermeasures by coating include starch, modified starch (oxidized starch, starch derivatives, etc.) and polyvinyl alcohol (hereinafter referred to as PVA).
This is a method of applying (externally adding) a surface treating agent to newsprint base paper, which is an effective means for improving the surface strength. Therefore, in the case of newsprint, the method of externally adding a chemical is an element that cannot be ignored in terms of improving the surface strength.

However, when a large amount of a chemical is used in the method of externally adding a chemical, the chemical exhibits tackiness when wet with water. There is a problem of causing troubles (phenomena called so-called "Nepari") due to adhesiveness such as hard peeling of printed papers or slipping of printed papers. Therefore, in the method of externally adding a chemical, it was necessary to consider the releasability of the coated product.

[0015]

However, among the measures for controlling the water absorption of newsprint paper, the method of internally adding a chemical such as a sizing agent that is also used in general printing paper (internal size) is as follows: Chemicals need to be added to the low consistency pulp slurry. (2) The fixed amount of chemicals on the pulp sheet is not constant. (Low fixation amount of chemicals) (3) Circulating white water is used. Therefore, it is difficult to control the amount of chemicals to be added, and it is necessary to add the chemicals excessively. This excessive addition tends to cause a decrease in paper strength, machine trouble, and significant white water stains.
There was a problem in terms of operability.

Further, changing the composition of the raw materials or changing the papermaking conditions is, for example, a large fluctuation of the raw materials in an actual machine, and is unsuitable as a temporary measure, but unsuitable as a long-term measure. .

The method of externally adding a surface treating agent such as starch, modified starch (oxidized starch, starch derivative, etc.), PVA, etc., which has been taken as a measure for surface strength, is certainly effective in terms of surface strength. The water absorption could not be improved.

It is also conceivable to externally add a surface sizing agent used for general printing paper. However, these surface sizing agents also need to have properties as surface strength countermeasure materials, and these surface sizing agents are compared with starch, modified starch (oxidized starch, starch derivative, etc.), PVA, etc.
Surface strength and water absorption could not be improved in a well-balanced manner. Further, it was not satisfactory in terms of material economy and peelability of the coated product.

Therefore, an object of the present invention is to provide a printing paper, particularly a newsprint paper, in which both water absorption and surface strength are improved in a well-balanced manner only by external addition of a chemical, and a method for producing the same.

[0020]

SUMMARY OF THE INVENTION The object of the present invention consists mainly of three components: modified starch (or starch), cationic (or amphoteric) polyacrylamide, and anionic water-soluble copolymer on a base paper for printing. The solution was achieved by providing a water absorption control layer. Although this method is effective for general printing paper, it is particularly effective for newsprint paper.

[0021] A modified starch (for example,
Oxidized starch, etherified starch, etc.), starch, nonionic polyacrylamide, cationic polyacrylamide (water-soluble polyacrylamide having a tertiary amine group or quaternary ammonium group), and amphoteric polyacrylamide applied alone Even though the surface strength could be improved, the water absorption could not be improved. For example, oxidized starch is applied to newsprint base paper
Even when applied in the range of 0.5 to 1.0 g / m ² , it was about several seconds by the drip water absorption method described later.

Further, the application of a copolymer having an anionic hydrophobic group alone could not improve the water absorption at a level at which there was no problem in the releasability.

As will be described later, it is considered that the water-absorbing control layer of the present invention can be considered to be based on an ionic complex. Examples of the application of such a complex to paper chemicals include, for example, an anionic paper-strengthening agent and a special cationic resin, which are described in the Journal of Japan Paper Industry Co., Ltd. (VOL.45, No.2, (1991) 245-249). A method is described in which a paper strength agent is mixed to form a high strength ion complex and a paper strength agent is added to the pulp slurry. However, this method is a method of internally adding a chemical, and is not intended to improve water absorption. Also, Japanese Patent Application Laid-Open No. 60-119297 discloses a paper sizing method using an anionic hydrophobic sizing agent and a cationic holding agent. However, this method is also a method of internally adding a chemical, and cannot solve the above-mentioned problems associated with internal addition.

On the other hand, JP-A-52-148211 and JP-A-56
JP-A-118995 and JP-A-3-54609 disclose a surface sizing method using a coating solution containing an anionic resin and a cationic resin. JP
JP-A-52-148211 discloses a method for producing a reinforced corrugated paper for cardboard using a coating solution containing an anionic resin and a cationic resin. However,
This method mainly aims at improving the compressive strength and the rigidity, and does not particularly aim at improving the water absorption. Further, in this method, the application amount is about 10 g / m ² , which is far from being applied to general printing paper. JP-A-56-118995 describes, for example, a method for producing an oil-resistant paper using a surface sizing agent composed of oxidized starch, vinylidene chloride / acrylamide copolymer, and polyethyleneimine. However, while oil-resistant paper is a paper for which resistance to oil is required, the printing paper of the present invention has high absorbency for oil (in other words, ink) in response to high-speed printing in offset printing. This is the paper that is sought and is the exact opposite technology. Japanese Patent Application Laid-Open No. 56-118995 discloses a surface sizing agent composed of a ketene dimer, a cationized starch and an anionic polymer, but has a problem of a decrease in friction coefficient.

Further, JP-A-62-122781 and JP-A-62-146674 disclose a recording medium for ink jet recording having an ink receiving layer containing a polymer complex of a basic polymer and an acidic polymer. A material is disclosed. However, in these publications, both polymers are dissolved in an organic solvent such as dimethylformamide,
Because it is a coating liquid, it is difficult to adapt to general printing paper. Further, the recording material for ink jet recording is required to have receptivity (in other words, absorbability) to an ink composed of a water-polyhydric alcohol mixed system, which is different from the water absorption degree required in the present invention. Things.

However, the present inventors have developed modified starch,
Or, by combining starch, a specific polyacrylamide, and a copolymer having an anionic hydrophobic group, the water absorption was improved only by external addition, and the surface strength and the releasability were improved in a well-balanced manner. It has been found that newsprint paper can be obtained, and the present invention has been completed.

That is, the present invention provides a newsprint paper comprising a paper surface provided with a coating layer containing a water-absorbing control composition mainly composed of the following three components: component A, component B and component C. About.

Component A: modified starch or starch Component B: 1) nonionic polyacrylamide 2) cationic polyacrylamide (water-soluble polyacrylamide having tertiary amine group) 3) cationic polyacrylamide (quaternary) Water-soluble polyacrylamide having an ammonium group) 4) Amphoteric polyacrylamide Water-soluble polyacrylamide selected from at least one of the above 1) to 4) Component C: a monomer having a hydrophobic substituent having 6 to 10 carbon atoms The anionic copolymer with a monomer having a carboxyl group or a sulfonic acid group, the water absorption control composition of the present invention, the component A,
It is composed mainly of three components B and C.

The component A used in the water-absorbing control composition of the present invention is a modified starch or a starch, or may be a mixture of a modified starch and a starch. The modified starch is described in detail in, for example, "Michinori Nakamura, Shigeo Suzuki: Starch Science Handbook, Asakura Shoten Co., Ltd., 1977, p496-522" and the like. (Ammonium persulfate (APS) modified starch, enzyme-modified starch, starch for thermochemical modification described in JP-A-60-28475,
Examples include thermochemically modified starch described in JP-A-163471, pregelatinized starch, oxidized starch, starch derivatives (eg, esterified starch, etherified starch, and crosslinked starch), and grafted starch. In the present invention, these starches may be used alone or in combination of two or more. Among these, gate roll coating suitability, that is,
Those having properties such as (a) high solution concentration and low viscosity, (b) high aging resistance, and (c) excellent film forming ability are preferred, and oxidized starch and etherified starch are more preferred.

Component B used in the water-absorbing control composition of the present invention is a specific water-soluble polyacrylamide having a cationic property (hereinafter abbreviated as PAM), and is a nonionic PAM or a cationic PAM (tertiary). PAM having an amine group and / or a quaternary ammonium group) and amphoteric PAM. Nonionic PAM is considered to have a part of the amide structure in the form of amidinium (-CONH ₃ ⁺ ) and to have a slight cationic property.
It can be used as the component B used in the present invention. Further, as the component B, each PAM may be used alone, or may be used as a mixture.

Each PAM used as the component B is prepared by subjecting the corresponding monomer to a conventionally known method, for example, a method such as an aqueous solution polymerization method, a solvent polymerization method, a reverse phase emulsion polymerization method, a precipitation polymerization method, or a suspension polymerization method. , Polymerization or copolymerization.

Nonionic PAM used as component B
As, for example, (meth) acrylamide (where,
(Meth) is used as an indication that it includes the presence of meth, and (meth) acrylamide means methacrylamide and / or acrylamide. The same shall apply hereinafter), a polymer or a copolymer, a non-ionic monomer copolymerizable with (meth) acrylamide and (meth)
Acrylamide copolymer and the like can be mentioned.

The cationic PAM and amphoteric PAM used as Component B are represented by the following formula:
PAM having a tertiary amine group and / or a quaternary ammonium group. Basically, a PAM having no anionic residue other than a cationic residue is a cationic PAM, while a PAM having an anionic residue other than a cationic residue is an amphoteric PAM. The ratio of the cationic residues in these PAMs is desirably 0.1 mol% or more. The ratio of cationic residues is 0.1
If it is less than mol%, the effect of the water absorption control tends to be slightly weakened.

Examples of the method of introducing a cationic residue into PAM include (a) a method of copolymerizing a monomer having a tertiary amine group or a quaternary ammonium group,
(b) a method of modifying a PAM polymer using a Mannich reaction, (c) a method of modifying a PAM polymer using a Hoffman decomposition reaction, and (d) copolymerizing a monomer having a tertiary amine group. After that, a method of converting to a quaternary ammonium group by a reaction such as alkylation, arylation, or the like can be given.

In the method of copolymerizing (a), (meth) acrylamide and a cationic monomer (tertiary amine group,
Alternatively, a copolymer having a quaternary ammonium group) may be used. In this method, the monomer having a tertiary amine group used includes, for example,
N, N-dimethylaminoethyl (meth) acrylate, N, N-
Diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminohydroxypropyl (meth) acrylate, N-
Methyl, N-ethylaminoethyl (meth) acrylate,
N, N-diphenylaminoethyl (meth) acrylate, N,
N-dimethylaminoethyl (meth) acrylamide, N, N-
Diethylaminopropyl (meth) acrylamide, N, N-
Dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinylpyridine and the like can be mentioned.

Examples of usable monomers having a quaternary ammonium group include (meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, and (meth) acryloyloxy. Ethyltriethylammonium chloride, (meth) acryloyloxyethyldiethylbenzylammonium chloride, (meth) acrylamidopropyltrimethylammonium chloride, (meth) acrylamidopropyltriethylammonium chloride, (meth) acrylamidopropyldimethylbenzylammonium chloride, diallyldimethylammonium chloride , Diallyldiethylammonium chloride, (meth) acryloyloxyethyltrime Such as Le ammonium sulfate are exemplified.

In the copolymerization method, (meth) acrylamide or a monomer copolymerizable with the above-mentioned cationic monomer may be used as long as the method does not hinder the present invention. Examples of the copolymerizable monomer include ethylene, butadiene, styrene, α-methylstyrene, isoprene, propylene, vinyl acetate, vinylcarbazole, vinylpyrrolidone, (meth) acrylonitrile, (meth) acrylate, and N-methylol. (Meth) acrylamide, methylenebisacrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-sulfoethyl (meth) acrylate, ethylenedi (meth) acrylate, acrylic acid, methacrylic acid, maleic acid , Fumaric acid, itaconic acid, muconic acid, crotonic acid, allyl glycidyl ether, glycidyl (meth) acrylate, sodium salt of ethylene sulfonate, sodium salt of p-styrene sulfonate, vinyl benzyl sulf Salts, and vinyl benzyl phosphonium salt.
When anionic monomers such as acrylic acid and itaconic acid are used among these monomers, an amphoteric PAM can be obtained.

In the method (d) for converting a tertiary amine group to a quaternary ammonium group, the alkylating agent used includes, for example, dimethyl sulfate, methyl chloride, methyl bromide, methyl iodide, chloride Benzyl, benzyl bromide and the like.

PAM used as component B of the present invention
Has a weight average molecular weight of about 10,000 to 4,000,000, more preferably 50,000 to 1,000,000. When the molecular weight is less than 10,000, PAM of component B
Cannot form a sufficient film and is not preferred in terms of surface strength and water absorption control. On the other hand, if the molecular weight is 400
If it is larger than 10,000, the viscosity of the PAM becomes high, which may cause operational problems.

Among the PAMs used as component B,
Cationic PAM (tertiary amine groups and / or quaternary
PAM having quaternary ammonium group), and amphoteric PAM
However, in terms of water absorption control (providing water absorption), it is more desirable than nonionic PAM. This is because in nonionic PAM, the cationicity derived from the partially existing amidinium structure is weak. Also,
Comparing the cationic PAM and the amphoteric PAM, the cationic PAM is more preferable when high water absorption is desired.

The component C used in the water absorption control composition of the present invention has an anionic monomer (a monomer having a carboxyl group or a sulfonic acid group) and a hydrophobic substituent composed of 6 to 10 carbon atoms. It is a copolymer with a monomer.

Examples of the monomer having a carboxyl group or a sulfonic group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, muconic acid, crotonic acid, and 2-acrylamido-2-methylpropanesulfonic acid. , 2-sulfoethyl methacrylate, styrenesulfonic acid, ethylenesulfonic acid and the like.

Examples of the monomer having a hydrophobic substituent include:
Styrene, α-methylstyrene, (meth) acrylate, maleate, olefins (for example,
Octene, decene, etc.).

In this copolymer, the ratio of the anionic monomer to the monomer having a hydrophobic substituent is from 60:40 to
A range of 10:90 is desirable. Each of the anionic monomer and the monomer having a hydrophobic substituent has at least 1
More than one kind may be used.

In the copolymer, a small amount of an anionic or nonionic monomer polymerizable with the above-mentioned anionic monomer and / or monomer having a hydrophobic substituent can be used as long as the present invention is not hindered. It may be polymerized.

Examples of the method for producing the copolymer include aqueous solution polymerization, solvent polymerization, reversed-phase emulsion polymerization, precipitation polymerization, and suspension polymerization.

This copolymer is, in other words, an anionic hydrophilic polymer, and preferably has an acid value in the range of 50 to 500, and more preferably 100 to 500.
Desirably in the range of 300. When the acid value is less than 50, the copolymer is not preferable because of insufficient water solubility and weak interaction with the component B. Also,
If the acid number is greater than 500, the copolymer is too bad anionic to be good.

The copolymer may have a weight average molecular weight of about 0.1 to 3,000,000, more preferably
A range of 0.1 to 100,000 is desirable. If the molecular weight is less than 0.1000, the copolymer of Component C cannot form a sufficient film, which is not preferable in terms of surface strength and water absorption control. On the other hand, when the molecular weight is larger than 3,000,000, there is a possibility that an operational problem due to the high viscosity of the coating liquid may occur.

The copolymer used as the component C is, specifically, a styrene / (meth) acrylic acid copolymer, a styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, ) Acrylic acid / (meth) acrylic acid ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid alcohol ester copolymer, olefin / maleic acid copolymer. Among them, styrene / (meth) acrylic acid copolymer, styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer, and olefin /
Maleic acid copolymers are more preferred in terms of imparting water absorption. In particular, the styrene / (meth) acrylic acid copolymer and the styrene / (meth) acrylic acid / (meth) acrylic acid ester copolymer are excellent in that the balance between the hydrophilic substituent and the hydrophobic substituent is excellent. Coalescence is more desirable.

As described above, the water-absorbing control composition of the present invention is mainly composed of the three components A, B and C. The ratio (weight ratio) of each component of the composition depends on the required degree of water absorption, the degree of releasability, or the amount of the composition to be applied to the newsprint paper to be produced. It cannot be limited. However, if limited, the ratio (A: (B + C)) of the component A and the remaining two components (component B + component C) is 10: 0.3
~ 0.3: 10 and the ratio of component B to component C (B: C) should be in the range of 20:80 to 80:20. (B + C)
= 10: 1 to 10:10 and B: C = 40:60 to 60:
A range of 40 is good.

The water-absorbing control composition used in the present invention only needs to be composed of the three components A, B and C. In the coating amount region described later, it is possible to obtain good releasability alone. Is possible. However, in order to further improve the releasability, in other words, in order to prevent Nepari, a range that does not hinder the present invention (for example, does not adversely affect water absorption, and foaming during coating is at a level that does not cause a problem in coating). And a small amount of an antiblocking agent may be added.
As the release component, for example, monoalkenyl succinate described in JP-B-63-58960, an anti-adhesive comprising an organic fluoro compound described in JP-A-6-57688,
An antiblocking agent containing a substituted succinic acid and / or a substituted succinic acid derivative described in JP 192995 as an active ingredient is exemplified. The addition rate of the antiblocking agent is suitably 5% or less (% by weight). When the addition ratio is higher than 5%, there is a possibility that a problem such as foaming during coating may be caused.

Although the water-absorbing control composition of the present invention basically does not require the use of other binder-like components, a range that does not hinder the present invention (particularly a range that does not affect the releasability). In some cases, such components are contained in small amounts. As other binder-like components, for example, celluloses such as methylcellulose, ethylcellulose, carboxymethylcellulose; latexes such as styrene / butadiene copolymer, styrene / acrylonitrile copolymer, styrene / butadiene / acrylate copolymer; Fully saponified PVA, partially saponified PVA,
PVAs such as amide-modified PVA, carboxy-modified PVA, and sulfonic acid-modified PVA; silicone resins, petroleum resins,
Various resins such as a terpene resin, a ketone resin, and a coumarone resin are exemplified. In particular, PVAs tend to increase the tackiness of wet paper when applied to paper,
When using in combination, sufficient attention must be paid to the amount of the combination.

The water-absorbing control composition of the present invention may contain an auxiliary agent such as a preservative, an antifoaming agent, an ultraviolet ray inhibitor, a fluorescent whitening agent, a viscosity stabilizer and a filler within a range not affecting the present invention. May be contained.

The base paper for newsprint used in the present invention includes ground pulp (GP) and thermomechanical pulp (TM).
P), mechanical pulp such as semi-chemical pulp (M
P), chemical pulp (CP) represented by kraft pulp (KP), deinked pulp (DIP) obtained by deinking waste paper containing these pulp, and disintegrated waste paper from the papermaking process The obtained recovered pulp, etc., alone,
Alternatively, they are mixed at an arbitrary ratio. The effect of the present invention is remarkable for base paper formed to a basis weight of less than 46 g / m ² . In the case of base paper having a basis weight of 46 g / m ² or more,
The surface strength is considered to be sufficient, and the dimensional change or strength reduction of the paper due to dampening solution during offset printing is considered to be negligible. It is not necessary to improve both properties and surface strength at the same time. Further, the blending ratio of DIP may be blended in an arbitrary range (0 to 100%). According to the recent trend of high blending of DIP,
A range of 30-70% is more preferred.

This newsprint base paper may be used as required.
White carbon, clay, silica, talc, titanium oxide, calcium carbonate, synthetic resin (vinyl chloride resin, polystyrene resin, urea formalin resin, melamine resin,
Papermaking fillers such as styrene / butadiene copolymer resins); paper strength agents such as polyacrylamide polymers, polyvinyl alcohol polymers, cationized starch, urea / formalin resins, melamine / formalin resins; acrylamide / Aminomethylacrylamide copolymer salt, cationized starch, polyethyleneimine, polyethylene oxide, acrylamide / sodium acrylate copolymer, etc., drainage / retention improvers; aluminum sulfate (sulfate band), UV inhibitor, anti-fading An auxiliary such as an agent may be contained. However, it is necessary to add these agents within a range that does not impair the water absorption control by external addition. The physical properties of the base paper need to be such that it can be printed by an offset printing machine, and may have any properties such as tensile strength, tear strength and elongation comparable to those of ordinary newsprint paper.

Further, as the base paper for newsprint, a paper having an internally added size may be used. However, in the present invention, there is also a meaning to solve the above-mentioned problems associated with the internal addition, and if anything, using the base paper without the internal sizing agent exerts the effect of the present invention more. Can be done. From the viewpoint of water absorption, a base paper having a drip water absorption of 10 seconds or less may be used in the drip water absorption method described below.

The newsprint paper having improved water absorption of the present invention may be provided on one or both sides of the aforementioned newsprint base paper.
It is manufactured by externally adding the above-mentioned water-absorbing control composition with a coating machine.

Two methods are known as methods for evaluating the water absorbency of the paper surface of low-size paper such as newsprint paper. One method is a drip water absorption method based on Japan TAPPI No.33. This method is a method in which 1 μl of water is dropped on paper and the time until the water droplet is absorbed by the paper is measured. Another method is a method of measuring a contact angle (contact angle method). In the present invention, 5 μl of water is dropped,
A method of measuring a contact angle of a water droplet after a lapse of a predetermined time (5 seconds) was adopted. The higher the water absorption (the higher the water absorption resistance), the longer the absorption time is in the drip water absorption method, and the larger the contact angle is in the contact angle method, and the longer it is maintained.

By providing a newsprint base paper with a coating layer containing the water-absorbing control composition of the present invention,
It is possible to control water absorption over a wide range from 10 seconds to 600 seconds by the drip water absorption method. In terms of the contact angle method, the water absorption can be controlled within the range of 75 to 95 degrees by the aforementioned method. That is, the water absorbency of newsprint paper can be controlled to a predetermined water absorbency by the type of each component, the mixing ratio of each component, the amount of the composition applied, and the like.

The degree of water absorption may be appropriately determined according to the specifications required for the product, and is not particularly limited. However, if it is intentionally limited, a range of 15 seconds to 150 seconds by the drip water absorption method is a more preferable degree of water absorption.

The water-absorbing control composition of the present invention exerts its effect effectively when the coating amount is in the range of 0.05 to 1.0 g / m ² (per one side). The coating amount is 0.05 g / m ²
If it is less than 1, the water absorption control composition cannot form a sufficient barrier layer, or the water absorption cannot be improved. On the other hand, even if the coating amount is higher than 1.0 g / m ² , there is a disadvantage that the releasability is deteriorated (a Neppari phenomenon occurs). It is also uneconomical in terms of cost. Considering the application to newsprint paper, the total amount of the water-absorbing control composition of the present invention is 0.1 to 0.5 g / m ² (per one side) in consideration of the surface strength, the releasability, and the like. Range is desirable. As a matter of course, the application amount should be determined according to the degree of water absorption required for newsprint paper, and is not particularly limited to that range.
It goes without saying that it is desirable to impart water absorbency with as little application amount as possible according to the required degree of water absorbency.

The coating machine includes a size press, a bar coater, an air knife coater, a gate roll coater,
And a blade rod metering coater.
Among these coaters, a transfer type coater such as a gate roll coater or a blade rod metering coater is preferable, and a gate roll coater is most preferable. The coating method using a transfer type coater is, for example, a method using a size press, in which a base paper is once immersed in a pound (liquid pool) of a coating liquid existing between rolls, while a desired coating amount is previously determined. Is a method in which a paint corresponding to the above is formed on the roll surface as a film having a certain thickness, and the paint film is applied to a base paper. Therefore, in the method using the transfer type coater, it is possible to apply the paint on the base paper surface very efficiently. As described above, in the newsprint paper of the present invention, since the coating amount is low, it is effective to use a transfer type coater (particularly, a gate roll coater and a blade rod metaling coater).

The water-absorbing control composition of the present invention exerts a great effect particularly when a system using a gate roll coater is used. That is, the water absorption control composition of the present invention can efficiently and efficiently improve the water absorption in the above-mentioned coating amount region by using a coating method using a gate roll coater.

In consideration of the maintenance of the coater, etc., the double-side coating by the gate roll coater is most preferable in the newsprint paper of the present invention. It goes without saying that an on-machine coater is desirable from the viewpoint of productivity.

That is, the water-absorbing control composition of the present invention can be used on newsprint base paper having a drip water absorption of 10 seconds or less.
The coating amount may be in the range of 0.05 to 1.0 g / m ^{2 using} a gate roll coater.

In the case of newsprint paper, it is said that the surface of the paper is not uniform, and it is difficult to provide a water-absorbing barrier layer on the paper surface in a low coating amount region by external addition.
However, the water absorbency control composition of the present invention,
There is an excellent feature that the effect can be obtained with a relatively low coating amount. In addition, this composition can improve water absorption with a smaller coating amount on the felt surface than on the wire surface.

Further, even when a coating layer containing the water-absorbing control composition of the present invention is provided on newsprint base paper, no decrease in friction coefficient is observed. For example, it is generally known that an anionic styrene / acid monomer copolymer, when applied to paper by a size press, lowers the dynamic / static friction coefficient of the coated paper. However, such a tendency is not recognized in the water-absorbing control composition of the present invention, and in particular, it is not necessary to incorporate an anti-slip agent. The dynamic friction coefficient of the newsprint paper of the invention is desirably in the range of 0.40 to 0.70.

The coating liquid containing the water-absorbing control composition of the present invention as a main component is also excellent in suitability for a gate roll coater. For example, when oxidized starch is applied alone by a gate roll coater, a considerably streaky pattern is observed on the coated product, whereas when the coating solution used in the present invention is applied, such a coating is obtained. Almost no streak-like pattern is recognized, and the coating can be applied more uniformly.

The newsprint paper of the present invention can control the water absorption in a wide range, so that it can be widely used for various inks used in printing. For example, special inks such as emulsion ink in which dampening water is mixed into oil-based ink, and inks having high tackiness for lithographic printing without water can be considered.

As described above, the improvement of newsprint paper is as follows.
Difficult compared to general printing paper. For this reason, it is impossible to directly convert the technology for general printing paper to the technology for newsprint paper. However, conversely, it is relatively easy to transfer the technology for newsprint paper to the technology for general print paper. Therefore, the water-absorbing control composition of the present invention can be applied not only to newsprint paper but also to general printing paper, and similar effects (for example, improved water-absorbing properties) can be obtained.

By using the water-absorbing control composition of the present invention, it is possible to easily produce printing papers of various types of brands having different sizes without using an internal size which tends to cause operational problems. It is. The printing paper also has improved surface strength at the same time.

[0072]

The base paper for printing paper, especially the base paper for newsprint, is coated with a water-absorbing control composition containing three components (components A, B, and C) as main components using a gate roll coater.
By coating in a low coating amount range of from 05 to 1.0 g / m ² , it is possible to obtain a sheet excellent in water absorption and surface strength and suitable for high-speed offset printing.

Although the clear reason has not been elucidated yet, it is presumed as follows.

It is considered that the water absorption control composition of the present invention, when applied to base paper and then dried, forms a hydrophobic complex film capable of controlling water absorption. That is, component B (cationic P
AM) and component C (an anionic water-soluble polymer having a hydrophobic group) form an ionic complex, and finally form a film in which hydrophobic substituents are oriented outward, and a hydrophobic surface is formed on the paper surface. It is believed that a barrier layer is obtained.

Component A (modified starch or starch)
Is useful for spreading the hydrophobic complex composed of the components B and C thinly and uniformly on the paper surface, and is considered to promote the formation of a hydrophobic barrier layer and also to improve the surface strength. . Considering only the point of improvement of water absorption, it can be considered that the coating can be carried out by the two-component coating of the components B and C. However, by using the component A, the coating of the components B and C is more effective than the coating of the two components. It is possible to reduce the amount of used, which is advantageous in terms of cost. Component B,
And component C is considered to form an ionic complex and contribute to improvement of water absorption as described above. In other words, the component B is the component C on the paper surface.
It is also considered that (anionic water-soluble polymer having a hydrophobic group) is retained from an ionic or chemical aspect.

[0076]

EXAMPLES The present invention will be described in detail below with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited thereto. In the description, parts and percentages indicate parts by weight and percentage by weight, respectively.

<Manufacture of newsprint base paper> DIP 35 parts,
Mix and disintegrate 30 parts of TMP, 20 parts of GP and 15 parts of KP,
The mixed pulp adjusted to have a freeness of 200 is paper-made at a papermaking speed of 1000 m / min using a Berbe-former-type paper machine.
An unsized, no-calender newsprint base paper of 43 g / m ² was obtained. (Drip water absorption = 5 seconds)

<Synthesis of Component B> [Synthesis Example 1] Synthesis of B-1 (cationic PAM) In a four-necked flask equipped with a reflux condenser, N, N-diethylaminoethyl methacrylate (7.8 g), 40 % Acrylamide aqueous solution (168.6 g) and water (300 g) were charged and heated to 60 ° C. under a nitrogen atmosphere, and then the reaction solution was mixed with a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium bisulfite (2 g). In addition, the mixture was reacted at 85 ° C. for 0.5 hour, and then cooled to obtain a polymer (B-1). The weight average molecular weight of this polymer was 220,000.

Synthesis Example 2 Synthesis of B-2 (Cationic PAM) In a four-necked flask equipped with a reflux condenser, N, N-diethylaminoethyl methacrylate (15.6 g) and a 40% aqueous acrylamide solution (160.8 g) ), And water (300g)
After heating to 60 ° C. under a nitrogen atmosphere, a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium hydrogen sulfite (2 g) were added to the reaction solution, and the mixture was reacted at 85 ° C. for 1 hour, and then cooled. Polymer (B-2) was obtained. The weight average molecular weight of this polymer was 720,000.

Synthesis Example 3 Synthesis of B-3 (Cationic PAM) In a four-necked flask equipped with a reflux condenser, N, N-diethylaminopropyl methacrylamide (7.8 g) and a 40% aqueous acrylamide solution (168.6 g) ) And water (300 g), and heated to 60 ° C. under a nitrogen atmosphere. To the reaction solution, a 1% aqueous solution of ammonium persulfate (15 g) and a 1% aqueous solution of sodium bisulfite (3 g) were added. After reacting for an hour, the mixture was cooled to obtain a polymer (B-3). The weight average molecular weight of this polymer was 2.2 million.

Synthesis Example 4 Synthesis of B-4 (Cationic PAM) In a four-necked flask equipped with a reflux condenser, an 80% aqueous solution of methacryloyloxytrimethylammonium chloride (13 g) and a 40% aqueous solution of acrylamide (168.6) g) and water (300 g), and heated to 60 ° C in a nitrogen atmosphere.
A 1% aqueous solution of ammonium persulfate (10 g
) And a 1% aqueous solution of sodium bisulfite (2 g) were added, and the mixture was reacted at 85 ° C for 1 hour, and then cooled to obtain a polymer (B-4). The weight average molecular weight of this polymer is
650,000.

Synthesis Example 5 Synthesis of B-5 (Amphoteric PA)
M) In a four-necked flask equipped with a reflux condenser, a 60% aqueous solution of methacryloyloxyethyldimethylbenzylammonium chloride (22.5 g) and a 40% aqueous solution of acrylamide (16%) were added.
0g), 80% acrylic acid aqueous solution (4.5g), and water (50g
), And heated to 60 ° C under a nitrogen atmosphere. To the reaction solution, a 1% aqueous solution of ammonium persulfate (10g) and a 1% aqueous solution of sodium bisulfite (2g) were added.
After reacting for 0.5 hours, the mixture was cooled and polymer (B-5)
I got The weight average molecular weight of this polymer was 60,000.

Synthesis Example 6 Synthesis of B-6 (Amphoteric PA)
M) In a four-necked flask equipped with a reflux condenser, a 60% aqueous solution of methacryloyloxyethyldimethylbenzylammonium chloride (22.5 g) and a 40% aqueous solution of acrylamide (20%) were added.
0g), and 80% aqueous acrylic acid solution (3.5g)
After heating to 60 ° C. under a nitrogen atmosphere, a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium hydrogen sulfite (2 g) were added to the reaction solution, and the mixture was reacted at 85 ° C. for 1.5 hours, and then cooled. Polymer (B-6) was obtained. The weight average molecular weight of this polymer was 1.25 million.

Synthesis Example 7 Synthesis of B-7 (Amphoteric PA)
M) A 60% acrylamidopropyldimethylbenzylammonium chloride aqueous solution (23.6 g) and a 40% acrylamide aqueous solution (200
g), 80% itaconic acid aqueous solution (4.0 g), and water (30 g)
) And heated to 60 ° C. under a nitrogen atmosphere. To the reaction solution, a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium hydrogen sulfite (2 g) were added, and the mixture was reacted at 85 ° C. for 1 hour. Upon cooling, a polymer (B-7) was obtained. The weight average molecular weight of this polymer was 820,000.

Synthesis Example 8 Synthesis of B-8 (Nonionic (Weak Cationic PAM)) A 40% aqueous acrylamide solution (177.8 g) and water (300 g) were placed in a four-necked flask equipped with a reflux condenser. After charging and heating to 60 ° C. under a nitrogen atmosphere, a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium hydrogen sulfite (2 g) were added to the reaction solution, and the mixture was reacted at 85 ° C. for 1 hour and cooled. Thus, a polymer (B-8) was obtained. The weight average molecular weight of this polymer was 850,000.

Synthesis Example 9 Synthesis of B-9 (Anionic PAM) An 80% aqueous acrylic acid solution (5.2 g) and a 40% aqueous acrylamide solution (174.0) were placed in a four-necked flask equipped with a reflux condenser.
g) and water (300 g), and heated to 60 ° C. under a nitrogen atmosphere. To the reaction solution, a 1% aqueous solution of ammonium persulfate (10 g) and a 1% aqueous solution of sodium bisulfite (2 g) were added. After reacting for 1 hour, cool down,
Polymer (B-9) was obtained. The weight average molecular weight of this polymer was 920,000.

<Component C> The following three types of polymers were used for component C. C-1: Styrene / maleic acid copolymer weight average molecular weight = 13000 C-2: Styrene / acrylic acid copolymer weight average molecular weight = 39000 C-3: α-olefin / maleic acid copolymer weight average molecular weight = 25000 * The oxidation value of C-2 is 230.

<Manufacture of Newsprint Paper> [Examples 1 to 20] Chemically modified starch (oxidized starch (trade name: SK-20)
/ Nippon Corn Starch Co., Ltd.) or a solution of etherified starch (trade name: PG-280 / Penford Products Co.)) with a polymer (B-1 to B-8) solution for component B, A solution of the polymer for component C (C-1 to C-8) was added at a predetermined blending ratio (see Table 1) to prepare a coating solution (solids concentration: 7 to 15%). This coating solution was applied to the aforementioned newsprint base paper with a Mayer bar. After the application, a calender treatment was performed to obtain newsprint paper.

[Comparative Examples 1 to 8] Coating solutions (solids concentration: 7 to 15%) were prepared using the components shown in Table 2 and their mixing ratios. This coating solution was applied to the aforementioned newsprint base paper with a Mayer bar. After application, perform a calendar process,
Newsprint paper for a comparative example was obtained.

With respect to the newsprint papers of Examples 1 to 20 and Comparative Examples 1 to 8, the coating amount and the drip water absorption were measured. The results are shown in Tables 1 and 2.

Measurement of coating amount: A sample (100 cm ² ) was cut, added to 50 ml of distilled water, and kept in a boiling water bath for 1 hour to extract starch. After filtering the extract, dilute the filtrate to 100 ml and sample 10 ml of it,
2.5 ml of 2N hydrochloric acid and 2.5 ml of a potassium iodide / iodine solution are added to bring the total volume to 50 ml. The absorbance at 580 nm was measured, and the amount of starch was measured from a previously prepared calibration curve. The amount of application was determined from the amount of the obtained starch and the mixing ratio of the application liquid by back calculation. -Measurement of drop water absorption: Measured with a dropping water volume of 1 µl according to Japan TAPPI No. 33 (Testing method for water absorption rate of absorbent paper).

[0092]

[Table 1]

[Table 2] [Examples 21 to 28] Coating solutions (solids concentration: 7 to 15%) were prepared using the components shown in Table 3 and their mixing ratios. This coating solution was applied to the aforementioned newsprint base paper with a gate roll test coater at a coating speed of 300 m / min in a predetermined coating amount range. After coating, perform super calendar treatment,
Newsprint paper was obtained.

[Comparative Examples 9 to 14] Coating solutions (solids concentration: 7 to 15%) were prepared using the components shown in Table 3 and their mixing ratios. This coating solution was applied to the aforementioned newsprint base paper with a Mayer bar. After application, perform a calendar process,
Newsprint paper for a comparative example was obtained.

For the newsprint papers of Examples 21 to 28 and Comparative Examples 9 to 14, the coating amount, drip water absorption, contact angle, Neppari strength, surface strength A (printing strength by a Prüfbau printing tester), and surface strength B (FRT (Fiber rising
test)) was measured. Table 3 shows the results.

Measurement of contact angle: Dynamic Absorption Tes
ter 1100 DAT (manufactured by Fibro), dropping water volume 5μl
And the contact angle after 5 seconds was measured. -Measurement of Neppari strength: Newsprint paper was cut into two pieces of 4 x 6 cm, the coated surface was immersed in water at a temperature of 20 ° C for 5 seconds, and the coated surfaces were brought into close contact with each other. Newsprint paper base paper is stacked on both outer sides and passed through a roll at a pressure of 50 kg / cm ² at 25 ° C and 60 ° C.
The humidity was adjusted at% RH for 24 hours. After forming a sample piece of 3 × 6 cm, the measurement was performed with a tensile tester at a tensile speed of 30 mm / min. The larger the measured value, the more difficult it is to peel off (in other words, the stronger the adhesiveness). In the newsprint paper of the present invention, a paper having a Neppari strength of 25.0 g / 3 cm or less was defined as “having good releasability”. -Measurement of surface strength: Surface strength is measured by two types of methods, namely, measurement of print strength by a Prüfbau printing tester,
And FRT (Fiber rising test) were measured, and those having both good measured values were defined as "excellent in surface strength".・ Surface strength A (printing strength by the Prüfbau printing tester) Red ink (manufactured by Dainippon Ink and Chemicals, Inc.) is placed on a rubber roll of the Prüfbau printing tester and placed on newspaper printing paper (printing area: 4 × 20 cm). , Printing pressure: 15N / m, printing speed: 6.0m / s
Coated with ec. The number of rising fibers when the rubber roll and newsprint paper were peeled off at the time of coating was measured with a microscope. The smaller the measured value, the higher the surface strength. In the present invention, the number of rising fibers of 20 or less is defined as “excellent in surface strength”.・ Surface strength B (FRT) Newsprint paper is cut in the machine direction to 300 mm x 35 mm width, and the surface analysis device FIBR 1000 (Fibro system AB)
Was used to determine the number of fluffs longer than 0.1 mm of the fiber in a fixed area (1 m ² ). The smaller the measured value, the better the surface strength. In the newsprint paper of the present invention, a sheet having 22 or less fuzz per 1 m ² was defined as “excellent in surface strength”.

[0096]

[Table 3] Regarding the coefficient of dynamic / static friction, even when the water-absorbing control composition of the present invention was applied, no particular deterioration was observed. For example, the newsprint paper dynamic friction coefficient of Example 21 = 0.45 Static friction coefficient = 0.57 Newsprint paper base paper Dynamic friction coefficient = 0.43 Static friction coefficient = 0.56.
The measurement of the dynamic / static friction coefficient is described in JAPAN TAPPI No.30-79
(Method of testing coefficient of friction of paper and paperboard).

[Example 29] Oxidized starch (SK-20), B-
4, and a release component (sodium salt of alkenyl succinic acid having 10 to 16 carbon atoms (described in JP-B-63-58960)) was further added to the solution comprising C-2 to prepare a coating solution. This coating solution was applied to the above-mentioned newsprint base paper at a coating speed of 300 m / min using a gate roll test coater. After coating, a super calender treatment was performed to obtain newsprint paper. Compounding ratio: A: B: C: Release agent = 10: 2: 2: 0.25 Coating amount: 0.30 g / m ² , Water absorption: 81 seconds, Neppari strength: 1
4.0g / 3cm Surface strength A: 10, Surface strength B: 16

[Example 30] Oxidized starch (SK-20), B-
1 and C-1 (used in Example 21; compounding ratio: A: B: C = 10: 1: 1) was mixed with high quality paper (basis weight: 78 g / m ² , water absorption: 9). Seconds), the water absorption was applied by a gate roll test coater at an application speed of 300 m / min. After coating, a super calendar treatment was performed. Coating amount: 0.32 g / m ² , water absorption = 82 seconds

[Example 31] Oxidized starch (SK-20), B-
4, and a solution consisting of C-2 (used in Example 23; blending ratio: A: B: C = 10: 2: 2) was mixed with high-quality paper (basis weight: 78 g / m ² , water absorption: 9). Second), coating was performed at a coating speed of 300 m / min with a gate roll test coater. After coating, a super calendar treatment was performed. Application amount: 0.40 g / m ² , water absorption = 110 seconds

Comparative Example 15 Oxidized starch (SK-20), B-
9 and C-1 (used in Comparative Example 9; blending ratio: A: B: C = 10: 5: 5) was mixed with high quality paper (basis weight: 78 g / m ² , water absorption: 9). Second), coating was performed at a coating speed of 300 m / min with a gate roll test coater. After coating, a super calendar treatment was performed. Application amount: 0.30 g / m ² , water absorption = 9 seconds

[0101]

By applying the water-absorbing control composition of the present invention with a gate roll coater, it is possible to obtain a printing paper having improved water-absorbing properties and a well-balanced surface strength and releasability. is there. In particular, newsprint paper is suitable for high-speed offset printing. In addition, in the newsprint paper of the present invention, the size can be imparted only by externally adding the water-absorbing control composition of the present invention without applying the internal additive size, and various problems associated with the internal addition of chemicals are obtained. Can be solved. Furthermore, it is easy to cope with a wide variety of varieties by arbitrarily changing the application amount, the mixing ratio, the type of the material, and the like of the water absorption control composition of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor, Tosumi Satake 5-2-1-1, Oji, Kita-ku, Tokyo Nippon Paper Industries Co., Ltd. Central Research Laboratory (56) References JP-A-58-4895 (JP, A) JP-A-7-157716 (JP, A) JP-A-7-138898 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21H 19/20

Claims (1)

(57) [Claims] 1. A printing paper comprising a printing paper base paper provided with a coating layer containing a water-absorbing control composition mainly composed of the following three components: component A, component B and component C. Component A: modified starch or starch Component B: 1) nonionic polyacrylamide 2) cationic polyacrylamide (water-soluble polyacrylamide having tertiary amine group) 3) cationic polyacrylamide (quaternary ammonium group) 4) Amphoteric polyacrylamide having at least one water-soluble polyacrylamide selected from the above 1) to 4) Component C: having a weight average molecular weight of 0.1 to 3,000,000 and a carbon number of 6 to
A monomer that having a 10 hydrophobic substituents, anionic copolymer of a monomer having a carboxyl group or a sulfonic acid group