JP3266903B2 - Newsprint paper with improved water absorption resistance and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printing paper having a high content of mechanical pulp having improved water absorption resistance and the like.
The present invention relates to newsprint paper and a method for producing them.

[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 (newspaper, newsprint paper) is generally made of mechanical pulp or deinked pulp (hereinafter referred to as "pulp").
“Deinked pulp” is abbreviated as “DIP”. ) Is the main type of paper, and is classified as middle or lower grade paper. On the other hand, newspaper printing ensures that the specified number of copies is printed within the specified time during the specified time. Have to do
Paper that requires more stringent quality than ordinary printing paper.
In this regard, newsprint paper is a special type of paper, and has its own classification in terms of paper classification. Recent newsprint papers are required to be lightweight and have a high DIP content.
Various improvements need to be made while overcoming the disadvantages of these points. In that sense, the improvement of newsprint paper is a severe one that is considerably different from the improvement of general print paper.

[0004] In recent years, with respect to newspaper printing, computer systems have been introduced into newspaper printing in view of various requirements (for example, a request for high-speed printing, a request for color paper, a request for various kinds of printing, a request for automation, etc.). Coupled with the time of
The transition from letterpress printing to offset printing is rapidly advancing.

The spread of offset printing requires newsprint paper to have a quality different from that of newsprint paper for letterpress printing. For example, (1) water absorption resistance is moderately maintained, wet strength is high, there is no drainage, (2) peel strength (Nepari) is low, and (3) paper dust is not generated. It is. Among the required qualities, in particular, retention of water absorption resistance, that is, control of water absorption resistance (in other words, provision of size) is an important issue.

However, newsprint paper having a high mechanical pulp content and hardwood bleached kraft pulp having a low mechanical pulp content (hereinafter, "hardwood bleached kraft pulp" is referred to as "LB
KP ”. The degree of difficulty in controlling the water absorption resistance (in other words, imparting size) is different from that of general printing paper having a high content of ()). When the content of mechanical pulp is high, LBKP is dense while the surface condition of the base paper is rough. Further, it is considered that the amount of application of the external additive size is large on a dense paper surface, but the amount of application of the external additive size is large on a rough paper surface.

In general printing paper, the water absorption resistance is controlled by, for example, a method of internally adding a chemical such as a sizing agent (internal size) or a method of externally adding (external size).
It is done by. Internal addition is a so-called wet end, a method in which an internal sizing agent is added to the pulp slurry so that the internal sizing agent is contained inside the paper simultaneously with papermaking. This is a method in which an external sizing agent is applied to the paper surface using a coating machine represented by a roll size press or a gate roll coater. As a matter of course, a coating machine represented by a gate roll coater or the like is used for newsprint paper.

As sizing agents for internal addition, reinforced rosin sizing agents, emulsion sizing agents, synthetic sizing agents and the like are used for acidic papermaking, and alkyl ketene dimer (AKD) and alkenyl succinic anhydride are used for 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.

Further, sizing agents for external addition (also referred to as surface sizing agents) include anionic polymers such as styrene / maleic acid copolymers and styrene / acrylic acid copolymers; rosin, tall oil, and the like. Anionic low molecular weight compounds such as saponified alkyd resins such as phthalic acid, and saponified petroleum resins and rosin; cationic polymers such as styrene-based polymers and isocyanate-based polymers are known. The paper is intended for paper having a high LBKP content, and the required degree of water absorption resistance and papermaking conditions are different.

On the other hand, the control of water absorption resistance in newsprint paper involves a high content of mechanical pulp.
The current situation is to deal with this by internally adding chemicals such as sizing agents and waterproofing agents.

[0011]

However, among the measures for controlling the water absorption resistance of newsprint paper, the method of internally adding a chemical such as a sizing agent that is also used for general print paper (internal size) is as follows. ) It is necessary to add chemicals to the low-concentration pulp slurry. (2) The fixing amount of the chemicals on the pulp sheet is not constant (the fixing amount of the chemicals is low).
(3) Since a plurality of paper machines usually use a common circulating white water, paper making that does not require size cannot be performed in parallel. (4) The effect of the retention aid is not stable.
If the yield is strengthened, DIP-based colored foreign matter is also incorporated into the sheet. (5) The water absorption resistance changes over time. (6) The neutralized and lightweight newspaper high-speed papermaking requires internal additive size. (7) When making newspaper printing paper containing 80% or more of DIP at a high speed of 1000 m / min or more, the internal sizing agent may have a tendency to decrease the yield of the sizing agent. Yield tends to decrease, it is difficult to have water absorption resistance, etc.There are many problems, it is difficult to control the amount of chemicals added, and depending on the situation, increase or decrease the internal sizing agent and the yield improver Had to be added.

When the internal sizing agent is not effective, the internal sizing agent is excessively added, resulting in a decrease in paper strength, machine trouble,
Adhesion and accumulation of the hydrophobic sizing agent easily causes remarkable white water stains and the like, and there are problems in terms of cost, quality, operability and the like. In addition, changing the raw material composition was not suitable as a temporary measure but was unsuitable as a long-term measure, due to large fluctuations of the raw material in the actual machine. In particular, in high-speed neutralization and lightweight high-speed papermaking, maintaining the same quality as conventional newsprint paper, or
Enhancing is an important technical issue for newsprint manufacturers.

As a measure for controlling the water absorption resistance of newsprint paper, a method of externally adding a chemical, in other words,
A method of externally adding a surface sizing agent used in general printing paper (external size) may be applied, but in practice, there is a problem that sufficient water absorption resistance cannot be obtained in terms of cost. Has not been put to practical use.

From the economical point of view, the application of a surface treatment agent to newsprint paper is generally performed by on-machine coating, and a gate roll coater, which is a film forming and transferring system capable of high-speed coating, is used. Is common. The feature of this gate roll coater method is, for example,
989) p36, Pulp and Paper Technology Times Vol. 36, No. 12 (1993) p
Although it is easily summarized in 20 etc., compared to the conventional 2-roll size press method used for general printing paper, it is possible to keep the coating liquid on the paper surface, and to improve the paper surface It is effective. That is, in the two-roll size press method, the base paper passes through the pond (liquid pool) of the coating liquid, so that the penetration of the coating liquid into the base paper is very large, whereas in the gate roll coater method,
Since the coating liquid forms a film in advance and the film is transferred, the coating liquid hardly permeates into the base paper. Therefore, in the gate roll coater method, it is described that the coating material tends to remain on the base paper surface.

Therefore, according to the present invention, newsprint paper having improved water absorption resistance (size) only by a method of externally adding a chemical, and drip absorption of 60 seconds or more at a coating amount of 0.3 g / m ² or less on one side. the provision of newsprint with a degree was a challenge.

[0016]

However, in the case of base paper for newsprint paper having a high content of mechanical pulp having a size of 10 seconds or less and having a high content of mechanical pulp, coating with a gate roll coater at a speed in the range of 300 to 1000 m / min. Also 0.3 g /
The m ² following coating amount, the coating solution is completely prevented from penetrating into the base paper, the ideal water resistant barrier can not be made the surface of the base paper, it revealed experimentally . That is, even if a surface sizing agent that is relatively easily applied to the base paper surface is used, and the coating is performed by a gate roll coater, a sufficient size effect (water absorption resistance) is obtained with an application amount of 0.3 g / m ² or less on one side. ).

The present inventors have proposed that mechanical pulp is used as a pulp component.
On newsprint paper base paper containing 30% by weight or more
Polyacrylamide and water-soluble anionic
Water absorption resistance control group consisting mainly of two copolymers
The coating layer consisting of the product is gated at a speed of 1100 to 1800 m / min.
0.1% on one side by coating with a troll coater
Having a 60 seconds or more drip water absorption degree at a coverage of ~0.3g / m ²
To obtain a newspaper printing paper,
Was solved. By this method, the surface treatment agent is
High water absorption resistance
You.

Nonionic polyacrylamide, cationic polyacrylamide (for example,
Water-soluble polyacrylamide having a tertiary amine group and / or a quaternary ammonium group) or amphoteric polyacrylamide alone can improve surface strength, but improve water absorption resistance. I couldn't. For example, oxidized starch is used for newsprint base paper,
Even when the coating amount was in the range of 0.5 to 1.0 g / m ² , the water absorption resistance of the coated product was about several seconds by the drip water absorption method described below, which was insufficient.

Further, even when the copolymer having an anionic hydrophobic group is applied alone, the effect of reinforcing the surface strength is insufficient, the generation of bubbles is large, and the water absorption of the drip water absorption is 60 seconds or more. No resistance is obtained.

In addition, these surface treatment agents could not improve the water absorption resistance at a level at which there was no problem in the releasability of the coated product.

As will be described later, it is considered that the water absorption resistance 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 in the Journal of Paper and Paper Technology 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 to a pulp slurry, and is not intended to improve water absorption resistance. 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 the 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-A-52-1
Japanese Patent No. 48211 describes 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 is mainly intended to improve the compressive strength and rigidity, and is not particularly aimed at improving the water absorption resistance. Further, in the example of this publication, the amount of applied chemical is also
It is about 10 g / m ² , which is far from being applied to general printing paper. JP-A-56-118995 describes a method for producing oil-resistant paper using a surface sizing agent composed of, for example, oxidized starch, a vinylidene chloride / acrylamide copolymer and polyethyleneimine. However, oil-resistant paper is paper that is required to have resistance to oil, whereas the printing paper of the present invention is compatible with ink (in other words,
This is a paper that is required to absorb oil (oil). Also, in JP-A-56-118995,
A surface sizing agent comprising a ketene dimer, a cationized starch and an anionic polymer is disclosed, but this surface sizing agent has a problem of a decrease in friction coefficient.

Further, JP-A-62-122781 and JP-A-62-146674 disclose a recording material for ink jet recording having an ink receiving layer containing a polymer complex of a basic polymer and an acidic polymer. Is disclosed. However, in these publications, since both polymers are dissolved in an organic solvent such as dimethylformamide to form a coating solution, it is difficult to adapt to printing paper having a high mechanical pulp content. In addition, mechanical pulp is hardly used for inkjet paper, and base paper having a high LBKP ratio is used. The recording material for inkjet recording is
Receptivity (in other words, absorptivity) is required for the inkjet ink composed of a water-polyhydric alcohol mixed system, which is different from the water absorption resistance required in the present invention.

However, the present inventors have found that a base paper for newsprint containing a high content of mechanical pulp contains a specific polyacrylamide and a polymer having an anionic hydrophobic group.
Improve water absorption resistance, and improve surface strength and peelability only by applying a coating layer composed of a water absorption resistance control composition combining a user with a gate roll coater at a coating speed of 1100 to 1800 m / min. It has been found that newsprint papers with improved balance can be obtained, and the present invention has been completed.

That is, the present invention provides a mechanical pulp having a coating layer containing a water-absorbing control composition mainly composed of the following two components A and B on a paper surface. Newsprint paper having a content of 30% by weight or more.

Component A: water-soluble polyacrylamide having cationicity Component B: water-soluble anionic copolymer of a monomer having a hydrophobic substituent and a monomer having a carboxyl group or a sulfonic acid group The water absorption resistance of the present invention The control composition comprises the above component A
And B are mainly constituted.

The component A used in the water absorption resistance control composition of the present invention is cationic polyacrylamide (hereinafter, “polyacrylamide” is abbreviated as “PAM”), and includes nonionic PAM and cationic PA.
M, amphoteric PAM.

Nonionic PAM used as component A
As, for example, (meth) acrylamide (where,
(Meth) is used as an indication that it includes a case where meth is present, and "(meth) acrylamide" means "methacrylamide and / or acrylamide". The same applies hereinafter), a copolymer, a copolymer of a nonionic monomer copolymerizable with (meth) acrylamide and (meth) acrylamide, and the like. These PAM is essentially a nonionic, a portion of the amide structure is Amidiniumu (-CONH ₃
⁺ ) It is said to be present in the form of a slightly weak cationic. Therefore, even nonionic PAM can be used as Component A in the present invention.

The cationic PAM and the amphoteric PAM used as the component A are, in short, PAM having a cationic monomer unit, and preferably a tertiary tertiary compound as the cationic monomer unit. PAM having a monomer unit having an amine group (or a tertiary amine base) and / or a monomer unit having a quaternary ammonium base is preferred. Basically, a PAM that does not contain an anionic monomer unit other than a cationic monomer unit is a cationic PAM, while a PAM that also has an anionic monomer unit in addition to a cationic monomer unit is an amphoteric PAM. .

When the cationic monomer unit is specifically mentioned, the monomer units represented by the general formulas [1] and [2] are more preferable.

[0031]

Embedded image

Embedded image (Here, R represents a methyl group or a hydrogen atom.
Y represents NH or an oxygen atom. Z is CH ₂ C
H (OH) CH ₂ or an alkylene group having 1 to 4 carbon atoms. R1, R2 and R3 represent an alkyl group having 1 to 18 carbon atoms, a benzyl group or a hydrogen atom. However, R1, R2 and R3 may be the same or different. X ion represents an anion, halogen atom ion (chlorine ion, bromine ion, iodine ion, etc.),
Sulfate ion, alkyl sulfate ion (methyl sulfate ion,
Ethyl sulfate ion), alkyl sulfonate ion,
Represents an arylsulfonate ion or an acetate ion. Examples of the method for introducing a cationic monomer unit into a PAM include (a) a method for modifying various PAMs using a Mannich reaction, (b) a method for modifying various PAMs using a Hoffman degradation reaction, c) a method of copolymerizing a monomer having a tertiary amine group or a quaternary ammonium group, and (d) a method of copolymerizing a monomer having a tertiary amine group, followed by a reaction such as alkylation or arylation. And a method of converting to a quaternary ammonium base.

As an example, in the method of copolymerizing (c), for example, (meth) acrylamide and a cationic monomer (a monomer having a tertiary amine group or a quaternary ammonium base), or (meth) What is necessary is just to copolymerize using an acrylamide derivative and a cationic monomer. In other words, in the present invention, it is possible to use, as the component A, a copolymer of (meth) acrylamide and a cationic monomer described below.

In this method, the monomers having a tertiary amine group used include, for example, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethyl Aminopropyl (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.

On the other hand, in this copolymerization method, usable monomers having a quaternary ammonium base include:
(Meth) acryloyloxyethyltrimethylammonium chloride, (meth) acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloyloxyethyltriethylammonium chloride,
(Meth) acryloyloxyethyl diethylbenzylammonium chloride, (meth) acrylamidopropyltrimethylammonium chloride, (meth) acrylamidopropyltriethylammonium chloride,
(Meth) acrylamidopropyldimethylbenzylammonium chloride, diallyldimethylammonium chloride, diallyldiethylammonium chloride,
(Meth) acryloyloxyethyltrimethylammonium sulfate and the like can be exemplified.

In this copolymerization method, (meth) acrylamide or a monomer copolymerizable with the above-mentioned cationic monomer may be used as long as it does not hinder the present invention. That is, in the present invention, a copolymer of (meth) acrylamide, a cationic monomer, and a copolymerizable monomer described below may be used as the component A in some cases.

The copolymerizable monomers used in this method include, for example, ethylene, butadiene, styrene, α-methylstyrene, isoprene, propylene, vinyl acetate, vinylcarbazole, vinylpyrrolidone,
(Meth) acrylonitrile, (meth) acrylate, N-methylolated (meth) acrylamide, methylenebisacrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-sulfoethyl (meth) acrylate , Ethylene di (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 sulfonium salt, vinyl benzyl phosphonium salt, etc. No. 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 base, the alkylating agent used includes, for example, dimethyl sulfate, methyl chloride,
Examples include methyl bromide, methyl iodide, benzyl chloride, benzyl bromide and the like.

In the present invention, PA used as Component A
As M, cationic PAM and amphoteric PAM are more preferably used than nonionic PAM from the viewpoint of water absorption resistance control (providing water absorption resistance). This is because nonionic PAM has a small effect of imparting water absorption resistance because the cationic property derived from the amidinium structure present in a part thereof is weak. In the cationic PAM and the amphoteric PAM, the ratio of the cationic monomer unit is desirably 0.1 mol% or more. When the ratio of the cationic monomer unit is less than 0.1 mol%, the effect of controlling the water absorption resistance tends to be slightly weakened. Furthermore, when comparing the cationic PAM and the amphoteric PAM, the cationic PAM is more preferable when high water absorption resistance is desired.

Each PAM used as the component A 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.

In the present invention, one kind of PA
M may be used alone, or two or more PAMs may be used as a mixture.

The weight average molecular weight of the PAM used as the component A of the present invention is suitably in the range of 200,000 to 4,000,000. When the average molecular weight of PAM is smaller than 200,000, such PAM cannot form a sufficient film, and the effect of imparting water absorption resistance and improving surface strength is insufficient. On the other hand, if the average molecular weight of the PAM is greater than 4 million, such a PAM may become too viscous and cause operational problems, resulting in unsatisfactory release of the coating. The average molecular weight of the PAM used is generally preferably “high in average molecular weight” from the viewpoint of imparting water absorption resistance and surface strength. It is believed that "low average molecular weight" is preferred. Therefore, the average molecular weight of PAM may be appropriately determined within the above-described range according to required specifications. PAM used when considering three factors, water absorption resistance, surface strength and peelability
Has an average molecular weight of preferably 500,000 to 2,000,000, and more preferably 700,000 to 1,200,000.

The component B used in the water absorption resistance control composition of the present invention is a copolymer of a monomer having a hydrophobic substituent and an anionic monomer (a monomer having a carboxyl group or a sulfonic acid group). is there.

The hydrophobic substituent may be any substituent having at least 6 carbon atoms, and is not particularly limited. What is necessary is just to determine suitably according to the problem of foaming of a coating material, the degree of required water absorption resistance, etc. As the hydrophobic substituent, for example, an alkyl group having 6 or more carbon atoms, an alkenyl group having 6 or more carbon atoms, a cycloalkyl group having 6 or more carbon atoms, an aryl group having 6 or more carbon atoms, or 7 carbon atoms The above aralkyl groups are exemplified.

Examples of the monomer having a hydrophobic substituent include:
For example, styrene monomers (eg, styrene, α-
Examples thereof include methylstyrene, chlorostyrene, cyanostyrene, and the like, olefin-based monomers (for example, hexene, octene, and decene), (meth) acrylates, and maleates. Such monomers are described in detail in "Polymer Data Handbook -Basic Edition-" Baifukan (1986), edited by The Society of Polymer Science, Japan (for styrene-based monomers, see Table 5-1 on page 47, olefins). For the system monomers, see Table 1
1, for acrylates, see Table 10-1,
Examples of maleic acid esters are given in Table 14-1 on page 162. Therefore, a monomer having a hydrophobic substituent may be selected from these.

Examples of the anionic monomer (monomer having a carboxyl group or a sulfonic acid group) include acrylic acid monomers (for example, acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, 2-ethylacrylic acid, -tert-butylacrylic acid, etc.), maleic monomers (for example, maleic acid, methylmaleic acid, phenylmaleic acid, chloromaleic acid, fumaric acid, itaconic acid, muconic acid, etc.), 2-acrylamidopropanesulfonic acid, 2 -Acrylamide-n-butanesulfonic acid, 2-acrylamide-n-hexanesulfonic acid, 2-acrylamide-n-octanesulfonic acid, 2-acrylamide-n-dodecanesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide-2-phenylpropanesulfonic acid, 2-acrylamide -2,4,4-trimethylpentanesulfonic acid, 2-acrylamide-2- (4-chlorophenyl) propanesulfonic acid, 2-methacrylamide
-n-tetradecanesulfonic acid, sodium 4-methacrylamidobenzenesulfonic acid, 2-sulfoethylmethacrylate, p-vinylbenzenesulfonic acid, styrenesulfonic acid, ethylenesulfonic acid and the like.

In this copolymer, the ratio of the monomer having a hydrophobic substituent to the anionic monomer is from 90:10 to
A range of 40:60 is desirable. At least one kind of each of a monomer having a hydrophobic substituent and an anionic monomer may be used.

Further, in the copolymer, anionic polymerizable with the above-mentioned monomer having a hydrophobic substituent and / or anionic monomer within a range not interfering with the present invention;
Alternatively, a small amount may be copolymerized with a nonionic monomer.

The method for producing the copolymer includes, for example, 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 A. Also,
If the acid value is greater than 500, the copolymer is too unionic and unfavorable.

The copolymer may have a weight average molecular weight of about 0.1 to 1,000,000, and more preferably.
A range of 0.1 to 100,000 is desirable. If the molecular weight is less than 0.1000, the copolymer cannot form a sufficient film, which is not preferable in terms of surface strength and water absorption resistance control. On the other hand, when the molecular weight is larger than 1,000,000, 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 B is, specifically, a styrene / (meth) acrylic acid copolymer, a styrene / (meth) acrylic acid / (meth) acrylic ester copolymer, a styrene / Maleic acid copolymer,
Styrene / maleic acid half ester copolymer, styrene /
Maleic acid ester copolymer, styrene / 2-acrylamidopropanesulfonic acid copolymer, (meth) acrylic acid / (meth) acrylic acid ester copolymer, α-olefin / maleic acid copolymer, olefin / acrylic acid copolymer Polymers and the like can be mentioned. Among them, styrene / acrylic acid copolymer, styrene / (meth) acrylic acid copolymer, styrene / maleic acid copolymer and α-
An olefin / maleic acid copolymer is more preferable in terms of imparting water absorption resistance. In particular, styrene / acrylic acid copolymers and α-olefin / maleic acid copolymers are desirable in that the balance between the hydrophilic substituent and the hydrophobic substituent is excellent. / Acrylic acid copolymer is most desirable.

The water absorption resistance control composition of the present invention is mainly composed of two components A and B as described above. Ratio of each component of this composition (weight ratio)
Is not necessarily limited because it depends on the required degree of water absorption resistance and releasability of the newsprint paper to be produced, or the amount of the composition applied. However, if we limit ourselves, component A and component B
Should be in the range of 20:80 to 80:20, and considering economics, more preferably, A: B =
The range of 40:60 to 60:40 is good.

The water absorption resistance control composition used in the present invention basically only needs to be composed of the two components A and B.
In the coating amount region described later, it is possible to obtain good releasability alone. However, in order to further improve the releasability, in other words, in order to prevent Nepari, a range in which the present invention is not hindered (for example, a level that does not adversely affect water absorption resistance and that foaming during coating does not cause a problem in coating). And a small amount of an anti-adhesive 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, and JP-A-6-129959
And a substituted succinic acid and / or a substituted succinic acid derivative described in Japanese Patent Application Laid-Open (JP-A) No. H11-15064 as an active ingredient.
The addition rate of the antiblocking agent (the ratio of the solid content of the antiblocking agent to the total solid content of the components A and B) is suitably 10% or less (% by weight). When the addition ratio is higher than 10%, there is a possibility that a problem such as foaming during coating may be caused.

Although the water absorption resistance control composition of the present invention basically does not require the use of other binder-like components, it does not impair the present invention (for example, a range which does not interfere with the releasability). )), A small amount of such a component may be contained. 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; PVAs such as fully saponified PVA, partially saponified PVA, amide-modified PVA, carboxy-modified PVA, sulfonic acid-modified PVA; anionic PAM
PAMs such as silicone resins, petroleum resins, terpene resins, ketone resins, and coumarone resins. In particular, when PVA is applied to paper, it tends to increase the adhesiveness of the paper when wet, so that when used in combination, sufficient attention must be paid to the amount of the combination.

The water absorption resistance control composition of the present invention contains a preservative, an antifoaming agent,
Auxiliaries and fillers such as UV inhibitors, anti-fading agents, fluorescent brighteners, viscosity stabilizers, and anti-slip agents may be contained.

[0056]

The base paper for newsprint containing 30% by weight or more of mechanical pulp as pulp used in the present invention is ground pulp (GP), thermomechanical pulp (TM).
P), mechanical pulp such as semi-chemical pulp (MP) 30
The remaining part is kraft pulp (K
Chemical pulp (CP) represented by P) and deinked pulp (DI) obtained by deinking waste paper containing these pulp
P) and a recovered pulp obtained by disintegrating broke from the papermaking process, etc., alone or in a mixture at an arbitrary ratio. In addition, DIP has a mechanical pulp content of almost 100%.
% Of such waste paper when manufactured from waste paper
Is considered mechanical pulp. 30 mechanical pulp as pulp
Prominent effective in newsprint paper of the invention containing wt% or more, a base paper sheet forming below the basis weight of ^{37g / m 2 ~43g / m 2} . In the case of a base paper having a basis weight of 46 g / m ² or more, the base paper has a sufficient surface strength, and a dimensional change or a decrease in strength of the paper due to dampening water during offset printing is negligible. Therefore, it is not always necessary to simultaneously improve both the water absorption resistance and the surface strength by externally adding a chemical.

On the other hand, the blending ratio of DIP of the base paper used in the present invention may be blended in an arbitrary range (0 to 70% by weight). According to the recent trend of high DIP blending, 30
A range of -70% by weight is more preferred.

This newsprint base paper is optionally filled with white carbon, clay, silica, talc, titanium oxide, calcium carbonate, synthetic resin (vinyl chloride resin, polystyrene resin, urea formalin resin, melamine resin). And a styrene / butadiene copolymer resin). Particularly in neutral papermaking, calcium carbonate is effective. Paper-strength enhancers such as polyacrylamide polymers, polyvinyl alcohol polymers, cationized starch, urea / formalin resins, and melamine / formalin resins;
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, the addition amount of these agents must be within a range that does not impair the water absorption resistance control of the water absorption resistance control composition of the present invention. 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.

The newsprint base paper may be a base paper having an internal size. However, in the present invention, there is also a meaning to solve the above-mentioned problem associated with the internal addition, and if anything, the use of base paper without the internal addition size makes the effect of the present invention more effective. be able to. That is, even without performing the internal addition size, it is possible to impart the same or higher water absorption resistance to the internal addition size by externally adding the water absorption resistance control composition of the present invention. For example, the water absorption resistance control composition of the present invention can be sufficiently applied to newsprint base paper of less than 10 seconds by a drip water absorption method described later.

The newsprint base paper of the present invention may be an acidic newsprint base paper or a neutral or alkaline newsprint base paper.

[0062] Two methods are known as methods for evaluating the water absorption resistance of a sheet of low sized paper such as newsprint paper. One method is a drip water absorption method based on Japan TAPPI No.33. This method uses 1 μl of water on paper.
Is measured by measuring the time until water drops are absorbed on the paper surface. Another method is a method of measuring a contact angle (contact angle method), in which 5 μl of water is dropped and a contact angle of a water droplet is measured after a predetermined time (5 seconds).
The higher the water absorption resistance (the higher the water absorption resistance), the longer the absorption time in the drip water absorption method, and the larger the contact angle in the contact angle method, and the longer it is maintained. In the present invention, a drip water absorption method was used as a method for evaluating water absorption resistance.

By providing a coating layer containing the water absorption resistance control composition of the present invention on newsprint base paper, the water absorption resistance can be controlled in a wide range from 10 seconds to 300 seconds by a drip water absorption method. It is possible. Also, in terms of the contact angle method, the water absorption resistance can be controlled by the above-described method, for example, when the contact angle is in the range of 75 to 95 degrees.
That is, the water absorption resistance of the manufactured newsprint paper is changed to a predetermined water absorption resistance by changing the type of each component of the composition of the present invention, the mixing ratio of each component, the coating amount of the composition, and the like. It can be controlled freely.

[0064]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has improved water absorption resistance.
Newsprint paper, one side of the newsprint base paper or on both sides, water absorption resistance control composition of the present invention at a machine speed 1100～1800M / min by gate <br/> roll coater, the coating
Amount fabric is prepared by coating so as to 0.1 to 0.3 g / m ^2.

The water absorption resistance control composition of the present invention
Is the coating amount (in other words, the solid content of component A and component B)
( Total shape and mass) of 0.1 to 0.3 g / m ² (per side)
In the range, it exerts its effect effectively. 0.1g /
When it is less than m ² , the water absorption resistance control composition of the present invention
May not be able to form a sufficient barrier layer.
Cannot be improved. On the other hand, the application amount is 0.3 g / m
Even if it is higher than ² , for example, the releasability deteriorates remarkably.
(Nepali phenomenon occurs.) Ma
It is also uneconomical in terms of cost. Application to newsprint paper
Considering the above, as described above, the water absorption resistance
Improve strength and peelability in a well-balanced manner
It is necessary to consider these three factors comprehensively.
Coating amount of the water absorption resistance control composition of the invention (in other words,
In other words, the sum of the solid contents of component A and component B) is 0.
Must be in the range of 1 to 0.3 g / m ² (per side)
It is.

The water absorption resistance control composition of the present invention uses a gate roll coater as a coating machine.
Is required. That is, as described above, the conventionally used surface sizing agent is, in the gate roll coater,
Although there was a drawback that the effect of imparting sufficient water absorption resistance could not be obtained, the composition of the present invention was also applied in this method by applying the composition in the above-mentioned coating amount range at a papermaking speed of 1100 to 1800 m / min. It is possible to improve the water absorption resistance efficiently.

The coating liquid containing the water absorption resistance 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.

Also when applied to newsprint paper, it is most desirable to apply the water absorption resistance control composition of the present invention to newsprint paper base paper using a gate roll coater. It goes without saying that an on-machine coater is desirable from the viewpoint of productivity.

That is, the water absorption resistance control composition of the present invention is applied to a newsprint base paper in an amount of 0.1 to 0.3 g.
/ M ² (per side) in a double-side coating with a gate roll coater.

In the case of newsprint paper, 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 relatively low coating amount region by external addition (particularly, a gate roll coater). It is supposed to be. However, the water absorption resistance control composition of the present invention has an excellent feature that the productivity is high at a coating speed of 1100 to 1800 m / min, a relatively low coating amount, and an effect of imparting water absorption resistance is recognized.

Even when a coating layer containing the water absorption resistance control composition of the present invention is provided on the surface of printing paper, no decrease in the coefficient of friction is observed. 2. Description of the Related Art Conventionally, 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 absorption resistance control composition of the present invention, and in particular, it is not necessary to incorporate an anti-slip agent. When applied to newsprint paper, the kinetic friction coefficient of the manufactured newsprint paper is preferably in the range of 0.40 to 0.70, and according to the present invention, a friction coefficient in this range can be obtained without an anti-slip agent. .

The water absorption resistance control composition of the present invention can improve the water absorption resistance with a smaller coating amount on the felt surface than on the wire surface.

Newsprint paper using the water absorption resistance control composition of the present invention can control the water absorption resistance in a wide range, and thus can be widely used for various inks used in printing. For example, special inks such as emulsion inks in which dampening water is mixed in oil-based inks, and inks having high tackiness for lithographic printing without water can be used.

As described above, the improvement of newsprint paper is as follows.
Difficult compared to general high quality printing paper. Therefore, it is impossible to directly convert a general printing paper technology into a newsprint paper technology. However, conversely,
It is relatively easy to transfer the technology for newsprint paper to the technology for general print paper. Therefore, the water absorption resistance control composition of the present invention can be applied not only to newsprint paper, but also to general printing paper, and has the same effect as that of newsprint paper (for example, water absorption resistance). Improvement, improvement of surface strength, etc.).

By using the water-absorbing resistance 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 that tends to cause operational problems. It is possible. The printing paper also has improved surface strength at the same time.

Water absorption resistance control composition of the present invention
On a newsprint base paper in the range of 0.1 to 0.3 g / m ² (one piece).
Paper making speed of 1100 to 1800 m / min.
By coating with a gate roll coater in the range of
Well-balanced water absorption resistance, surface strength and peelability
Obtain newsprint paper suitable for improved high-speed offset printing
Can be As for the reasons, the obvious reasons are:
Although not yet elucidated, it is estimated as follows.

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

From the viewpoint of improving the water absorption resistance alone, it is considered that the water absorption resistance can be improved only by the component B. However, the component A can be converted into an ionic, Or, it is effectively retained from a chemical aspect or the like, and seems to work very advantageously in forming the film (in other words, improving the water absorption resistance).

Further, it is considered that the component A greatly contributes to the improvement of the surface strength in addition to the holding action of the component B.

However, when the water absorption resistance control composition of the present invention was used as a gate roll coater at a coating speed of 1100 m / min or less, the water absorption resistance was not sufficient.
On the other hand, when applied at a coating speed of 1100 m / min or more, even if the coating amount is as low as 0.1 to 0.3 g / m ² (per one side), sufficient water absorption resistance of 60 seconds or more in drip water absorption is obtained. Obtained. The reason for this is presumed to be that the water absorption resistance control composition is dried before it penetrates into the base paper by coating at a high speed, and the proportion of the water absorption resistance control composition present on the base paper surface increases. .

[0081]

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.

<Synthesis of PAM> In a four-necked flask equipped with a reflux condenser, 80% methacryloyloxyethyltrimethylammonium chloride (7.8 g), 40% aqueous acrylamide solution (168.6 g) and ion-exchanged water (300 g) And heated 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, reacted at 85 ° C. for 1 hour, and then cooled to obtain a cationic PAM. The weight average molecular weight of this PAM was 740,000.

<Preparation of Coating Solution> PAM applicable to the present invention
An aqueous solution (component A) of the above and an aqueous solution (component B) of an anionic copolymer having a hydrophobic substituent are added at a predetermined ratio to easily prepare a coating solution of the water absorption control composition of the present invention. be able to. Coating solutions that produce insoluble precipitates when mixed are not preferred in the present invention.

<Manufacture of newsprint base paper> DIP (deinked pulp) 35 parts, TMP (thermomechanical pulp) 30
Parts, 20 parts GP (ground pulp) and 15 parts KP (kraft pulp).
ml of the mixed pulp prepared at a papermaking speed of 1100 to 1800 m / min using a Berbeformer type paper machine.
A no-calendar newsprint base paper was obtained. This base paper has a basis weight of 43 g / m ² , a density of 0.65, a whiteness of 51%, and a smoothness of 60.
Seconds, the coefficient of static friction was 0.45, and the coefficient of kinetic friction was 0.56. The paper quality (for example, strength, etc.) other than the water absorption resistance of ordinary newsprint paper was the same base paper. This base paper did not contain an internal sizing agent, and the degree of water absorption resistance was 5 seconds by a drip water absorption method.

<Manufacture of Newsprint Paper> [Examples 1 to 5] A styrene / acrylic acid copolymer (weight average molecular weight: 39) was added to an aqueous solution of cationic PAM.
000, an oxidation value of 230) in a mixing ratio of 1: 1 (weight ratio of solids), and further, a release component (sodium salt of alkenyl succinic acid having 10 to 16 carbon atoms (Japanese Patent Publication No. 63-58960). Description)) was added to prepare a coating solution. Using a gate roll coater, the obtained coating solution was applied on the F side of the above-described newsprint base paper at a coating speed of 1100 m / min.
Coating was performed at 1200 m / min, 1300 m / min, 1500 m / min, and 1800 m / min. After the application, a super calendar treatment was performed to obtain newsprint paper. Compounding ratio: PAM / styrene / acrylic acid copolymer / release agent = 1/1 / 0.05

[Comparative Examples 1 to 5] An aqueous solution of a styrene-acrylic acid polymer was mixed with an aqueous solution of the same coating agent as in Examples 1 to 5, that is, an aqueous solution of cationic PAM, at a mixing ratio of 1: 1 (solids weight). Ratio) and a release component (sodium salt of alkenyl succinic acid having 10 to 16 carbon atoms (JP-B 63-58960).
Was added to prepare a coating solution. Using a gate roll coater, apply the obtained coating solution to the F side of the same newsprint base paper as in Examples 1 to 5 at a coating speed of 30%.
Coating was performed at 0 m / min, 600 m / min, and 1000 m / min. Further, the coating was performed while changing the coating amount. After the application, a super calendar treatment was performed to obtain newsprint paper.

The newsprint papers of Examples 1 to 5 and Comparative Examples 1 to 5 were measured for coating amount, drip water absorption, contact angle and Neppari strength by the following methods. Table 1 shows the results.

Measurement of coating amount: The nitrogen content was determined by the Kjeldahl method and converted.・ Drip water absorption measurement: Japan TAPPI No.3 as described above
Followed 3. -Measurement of Neppari strength: Two samples were cut into 4 x 6 cm pieces, and the coated surfaces were immersed in water at a temperature of 20 ° C for 5 seconds, and the coated surfaces were brought into close contact with each other. Overlay newsprint base paper on both outer sides,
Pass through a roll at a pressure of 50 kg / m ² at 25 ° C and 60% RH
Conditioned 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 30.0 g / 3 cm or less was defined as "having good releasability". Note that "torn." Means that when the sample was peeled off with a tensile tester, no peeling occurred on the bonding surface, and a delamination phenomenon of the sample itself occurred. In other words, it means that the adhesiveness is so high that it cannot be measured by this measuring method.

Table 1 As shown in Table 1, by applying at a coating speed in the range of 1100 to 1800 m / min, the coating efficiency is improved even with a low coating amount, and the drip absorption is improved to 80 seconds or more. did it. On the other hand, at a coating speed in the range of 300 to 1000 m / min, even if the coating amount was large, the coating efficiency could not be improved and the water absorption resistance, that is, the water absorption by drip could not be improved. 300 to 1000m /
At a coating speed in the range of minutes, increasing the coating amount to improve the drip water absorption increases the Neppari strength and causes a quality problem.

[0090]

The water absorption resistance control composition of the present invention is coated with a gate roll coater at a papermaking speed of 1100 to 1800 m / min, whereby the water absorption resistance is improved and the surface strength and peelability are improved. It is possible to obtain printing paper having a good balance. In particular, newsprint paper suitable for high-speed offset printing is obtained. Further, in the newsprint paper of the present invention, the size can be imparted only by externally adding the water-absorbing resistance control composition of the present invention without applying the internal additive size, and various properties accompanying the internal addition of chemicals can be obtained. It is also possible to solve the problem. Furthermore, the coating amount of the water absorption resistance control composition of the present invention,
By arbitrarily changing the mixing ratio, the type of material, and the like, it is easy to support a wide variety of varieties.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-13298 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42

Claims (7)

(57) [Claims] 1. A newsprint base paper containing 30% by weight or more of mechanical pulp as a pulp component and having a drip water absorption of 10 seconds or less (based on Japan TAPPI No. 33, measured with a dropping water amount of 1 μl). A newsprint paper provided with a gate roll coating layer composed of a water absorption resistance control composition mainly composed of two components A and B, wherein the gate roll coating layer has a speed of 1100 m / min to 1800 m / min. Newsprint paper characterized in that the coating amount of the water absorption resistance control composition is in the range of 0.1 to 0.3 g / m ² (per one side) and the drip water absorption is 60 seconds or more. Component A: Cationic water-soluble polyacrylamide Component B: Water-soluble anionic copolymer of a monomer having a hydrophobic substituent and a monomer having a carboxyl group 2. The newsprint paper according to claim 1, wherein
Component A, which is one of the components constituting the water-absorbing control composition, is a cationic polyacrylamide having a tertiary amine group and / or a quaternary ammonium base,
Alternatively, newsprint paper characterized by being an amphoteric polyacrylamide. 3. The newsprint paper according to claim 1, wherein the newsprint base paper has a basis weight of 40 g / m ² to 43 g.
Newsprint paper characterized in that the weight is reduced to the range of g / m ² . 4. The newsprint paper according to claim 1, wherein the component B, which is one of the components constituting the water-absorbing control composition, comprises a styrene monomer and an acryl monomer. Newsprint paper characterized by being a water-soluble anionic copolymer with an acid monomer. 5. The newsprint paper according to any one of claims 1 to 4, wherein the ratio of the components A and B constituting the water-absorbing control composition (solids weight ratio).
Wherein A: B = 20: 80 to 80:20. 6. The newsprint paper according to claim 1, wherein the drip water absorption is in a range of 100 seconds to 500 seconds. 7. A newsprint base paper containing 30% by weight or more of mechanical pulp as a pulp component and having a drip water absorption of 10 seconds or less (measured in accordance with Japan TAPPI No. 33 with a dropping water volume of 1 μl). A method for producing newsprint paper provided with a coating layer containing a water absorption resistance control composition mainly composed of two components A and B, wherein the coating layer is formed by a gate roll coater at 1100 m / min to 1800 m. A method for producing newsprint paper, wherein the method is applied at a rate of / min and the drip water absorption is 60 seconds or more. Component A: Cationic water-soluble polyacrylamide Component B: Water-soluble anionic copolymer of a monomer having a hydrophobic substituent and a monomer having a carboxyl group