JP5435383B2 - Newsprint paper for offset printing - Google Patents

Description

Detailed Description of the Invention

  The present invention relates to a newsprint for offset printing that does not cause piling and nippar trouble during printing.

  In recent years, newspapers for offset printing are often used for color printing, and the higher the whiteness of the base paper, the better the appearance of color printing. Yes. In addition, the newspaper for offset printing is required to be lightweight (low basis weight). Paper with a low basis weight tends to show through on the front surface when viewed from the back side, and through printing tends to occur on color printing to which a relatively large amount of ink is applied. Therefore, high opacity is required even with a low basis weight.

As a method for improving the whiteness of newsprint, a method of internally adding a filler is employed. Adding a filler can increase whiteness and opacity.
As fillers usually used for newsprint, white carbon, talc, clay, titanium dioxide, calcium carbonate, urea formalin resin, and the like are used. For example, since titanium dioxide has a very high light scattering coefficient, it is effective for improving the opacity, but it is expensive and is not widely used in newsprint. Talc and kaolin are inexpensive, but their oil absorption is not so high. Since calcium carbonate decomposes in acidic papermaking, its use is limited to neutral papermaking. Accordingly, white carbon having a particularly high oil absorbency has a high effect of improving opacity after printing with a relatively small addition amount and is often used.

  However, when these fillers are added in an increased amount, the yield of the paper machine wire is deteriorated, and there is a problem that the filler tends to fall off from the paper at the time of printing and is taken up by the blanket. In order to prevent piling, the coating amount of a water-soluble adhesive such as starch or polyacrylamide applied on the surface is increased. Nepari is a phenomenon in which the dampening water adhering to the base paper in offset printing causes adhesives to increase the tackiness of the paper surface. If a Nepari trouble occurs, the paper sticks to the blanket or the paper breaks. Sometimes. In other words, piling can be reduced by increasing the amount of adhesive applied, but increasing the amount of adhesive applied has the contradictory property of causing Nepari trouble, making it difficult to improve both simultaneously. ing.

Specifically, the following techniques have been proposed as a method for solving the Neppari trouble.
(1) Newsprint paper for offset printing in which the product of the viscosity and the coating amount of a surface treatment agent containing a specific processed starch is in a specific range. (Patent Document 1)
(2) Newsprint paper for offset printing, which contains an olefin-based sizing agent in a pigment coating layer having a dry coating amount of 0.3 to 3 g / m ² . (Patent Document 2)
(3) Newsprint paper for offset printing provided with a pigment coating layer containing a sizing agent in which the calcium carbonate contained in the base paper is 2% or more and less than 5% and the coating amount is 3 g / m ² or less. (Patent Document 3)
Further, there is the following patent document as a technique for obtaining a neutral paper excellent in size by specifying an internally added sizing agent and a surface sizing agent.
(4) Neutral paper containing a quaternary amine starch derivative having a substitution degree of 0.02 to 0.05 as a starch derivative and using an alkyl ketene dimer or alkenyl succinic anhydride as an internal sizing agent, A method for producing neutral paper, which comprises coating an aqueous solution of an anionic styrene-acrylonitrile copolymer. (Patent Document 4)
JP 2006-118114 A JP 2006-169693 A JP 2007-162173 A Japanese Patent No. 3205971

The invention described in Patent Document 1 specifies the composition, viscosity, and coating amount of the surface treatment agent, but does not specify the sizing agent contained in the base paper as in the present invention.
The invention described in Patent Document 2 uses an olefin-based sizing agent as a surface sizing agent in the pigment coating layer, but is not specified for the sizing agent contained in the base paper.
In the invention described in Patent Document 3, it is said that the pigment coating amount is preferably 0.5 g / m ² or more. Since the pigment coating amount is large, the coating amount of the adhesive is also large, and piling and It seems difficult to balance trouble prevention and ensure ink drying.
The invention described in Patent Document 4 is intended to obtain a neutral paper excellent in sizing properties immediately after papermaking by specifying the sizing method of the base paper and the components of the surface sizing agent. Not a thing.
As described above, the conventional technology cannot provide newsprint paper for offset printing that suppresses the occurrence of piling and Nepari trouble.

In order to solve the above problems, the present invention has the following configuration.
(1) Low-viscosity starch having a B-type viscosity of 7 mPa · s or less at 50 ° C. and 7%, an olefin-based surface sizing agent, and a surface mainly composed of kaolin as a pigment on both surfaces of a base paper containing an alkyl ketene dimer The treatment agent is coated and dried, the coating amount of the kaolin is 0.01 to 0.03 g / m2 on one side, the Nepari strength is 50 mN / 30 mm or less, the water absorption time (in JAPAN TAPPI No. 32-2 Newsprint paper for offset printing, characterized in that the amount of dripping water (5 μl) is 30 to 80 seconds.
(2) The content of the alkyl ketene dimer contained in the base paper is 0.01 to 0.5% by mass, the coating amount of the low-viscosity starch is 0.2 to 1.0 g / m 2 on one side, and the surface treatment agent The newspaper for offset printing according to (1), wherein the mass ratio of the low-viscosity starch and the olefin-based surface sizing agent contained in is in the range of 99: 1 to 70:30.

  According to the present invention, it is possible to obtain a newsprint for offset printing that is free from occurrence of piling and trouble.

Embodiments of the present invention will be described below.
The newsprint for offset printing according to the present invention uses waste paper deinked pulp (DIP) as the main component of the raw material pulp. In DIP, waste newspapers and magazine waste papers are usually disaggregated in a disaggregation step, then dust is removed in a dust removal step, a deinking agent is added in the deinking step, and ink is floated and separated by a flowator. And after removing a foreign material in a selective process, bleaching is performed in a bleaching process.
Moreover, as pulp used in conjunction with DIP, mechanical pulp or chemical pulp is used. Examples of the mechanical pulp include stone ground pulp (SGP), pressurized stone ground pulp (PGP), refiner ground pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and the like. Examples of the pulp include softwood kraft pulp (NKP), hardwood kraft pulp (LKP), and the like, which can be appropriately selected from these pulps. Mechanical pulp is preferably used in terms of opacity, and chemical pulp is preferably used in terms of strength.

The newsprint paper for offset printing of the present invention can be added with publicly known fillers and papermaking chemicals as required. As filler, white carbon, clay, silica, talc, titanium oxide, calcium carbonate, synthetic resin filler (vinyl chloride resin, polystyrene resin, urea formalin resin, melamine resin, styrene / butadiene copolymer resin, etc.) etc. Can be added. Especially in neutral papermaking, calcium carbonate is effective in terms of the effect of improving whiteness and opacity and cost. Papermaking chemicals include polyacrylamide polymers, polyvinyl alcohol polymers, cationized starch, urea / formalin resins, melamine / formalin resin and other paper strength enhancers, and acrylamide / aminomethylacrylamide copolymers. Yield improver such as salt, cationized starch, polyethyleneimine, polyethylene oxide, acrylamide / sodium acrylate copolymer, rosin sizing agent, emulsion sizing agent, alkyl ketene dimer (AKD), sizing agent such as alkenyl succinic anhydride , An auxiliary such as aluminum sulfate (sulfate band), dye, slime control agent, pitch control agent, antifoaming agent and the like may be contained.
The physical properties of the newsprint for offset printing need to be printable by an offset printing machine, and any physical properties such as tensile strength, tear strength, and elongation equivalent to those of ordinary newsprint for offset printing may be used. .

  Neutral papermaking sizing agents include reactive sizing agents that react directly with cellulose and cationic sizing agents that have self-fixing properties. Reactive sizing agents include alkyl ketene dimers, alkenyl succinic anhydrides, and other various derivatives. On the other hand, the cationic sizing agent has a defect that the effect at a low blending ratio is low as compared with the reactive sizing agent. Alkyl ketene dimer-based sizing agents are relatively stable and effective even at low addition amounts, but there is a problem that the rise of the size effect is slow, and the size is difficult to adjust because the size changes over time. In addition, alkenyl succinic anhydride has the disadvantage that it requires an emulsifying operation immediately before use, and that it easily causes machine contamination at a high addition amount.

In the present invention, an alkyl ketene dimer sizing agent is used as the sizing agent. Conventionally, in varieties that contain a lot of mechanical pulp and used paper pulp such as newsprint, there are many anionic trashes in the papermaking system, so the alkyl ketene dimer that is cationically emulsified settles on the anionic trash, Fixing is poor, and there is a problem that the amount added is too large to achieve the target sizing degree. In the present invention, the addition amount of the internally added alkyl ketene dimer is reduced, and the sizing degree is supplemented with the surface sizing agent to obtain the target sizing degree.
The reason for using an alkyl ketene dimer-based sizing agent in the present invention is that the degree of sizing is low at the time of coating the surface treatment agent, and the penetration of the surface treatment agent is promoted to prevent piling and nippar trouble, and printing. In some cases, water absorption resistance is imparted to the base paper by changing the sizing degree over time.

  That is, as described above, the alkyl ketene dimer is a reactive sizing agent, and has the characteristics that the rise of the size effect is slow and the sizing degree changes with time, and when the surface treatment agent is applied, the sizing degree of the base paper is almost the same. Since it is not expressed, the penetration of the surface treatment agent can be promoted. In other words, by using an alkyl ketene dimer, the sizing degree of the base paper at the time of coating the surface treatment agent can be reduced compared with the case of using other sizing agents, so that the penetration of the surface treatment agent is increased. be able to. The addition amount of the alkyl ketene dimer sizing agent for exhibiting this effect to the base paper is 0.01 to 0.5% by mass. If it is less than 0.01% by mass, the sizing degree at the time of printing will be insufficient, and if it is more than 0.5% by mass, the width of the sizing will change over time, so the sizing degree at the time of printing will be controlled to the desired value. Becomes difficult.

In the present invention, a surface treatment agent containing an adhesive and a surface sizing agent is applied and dried on both sides of the base paper.
As the adhesive used in the present invention, low-viscosity starch is used. The viscosity is 7 mPa · s or less as a B-type viscosity measured at a concentration of 7% and a temperature of 50 ° C. Examples of the low-viscosity starch include dry starch and the like, for example, dry low molecular weight hydroxyethylated starch. This dry-type low-viscosity hydroxyethylated starch is prepared by subjecting hydroxyethylated starch to a solid state with a water content of 5 to 17%, and acid-treating with hydrogen chloride gas, hydrochloric acid, sulfuric acid or the like, or ammonium persulfate, hydrogen peroxide, It has been reduced in molecular weight by oxidation treatment with chlorine gas or the like. Such a low-viscosity starch is less likely to cause Nepari trouble, and penetrates into the base paper during coating. As an adhesive, polyacrylamide, polyvinyl alcohol, latex or the like may be used in combination with the low viscosity starch.

  Here, AKD is added to the base paper as an internal sizing agent, but when the surface treatment agent is applied, the size effect of AKD is not expressed and the penetration of the surface treatment agent into the base paper is further increased. Since the amount of the surface treatment agent remaining on the surface is reduced, it is possible to prevent Nepari trouble.

  As surface sizing agents, alkyl ketene dimers, alkenyl succinic anhydrides, styrene acrylics, styrene acrylates and the like are generally known. In the present invention, olefin surface sizing agents are used. The olefin-based surface sizing agent has a less tendency to have Nepari than other surface sizing agents, and can prevent Nepari trouble.

  The olefin surface sizing agent used in the present invention is a copolymer containing an olefinic unsaturated monomer as a constituent monomer. Specifically, it is a copolymer comprising an olefinically unsaturated monomer which is a hydrophobic unsaturated monomer and a carboxy group-containing unsaturated monomer as constituent elements.

By combining the above configurations, the newsprint for offset printing of the present invention has a Nepari strength of 50 mN / 30 mm or less. Here, the Nepari intensity is a value measured as follows.
Cut two newspapers for offset printing 1 inch wide x 19 cm long, float the coated surfaces on a water surface at a temperature of 20 ° C for 5 seconds, and then immediately coat the coated surfaces (wet coated surface and wet coated surface) Adhere. Subsequently, the backing sheet is overlapped on both outer sides, passed twice through a roll at a nip pressure of 40 kgf / cm, and conditioned at 23 ° C. and 50% RH for 24 hours. The peel strength is measured with a tensile tester under conditions of a pulling speed of 100 mm / min. The larger the measured value, the harder it is to peel off (stronger adhesiveness).

  Furthermore, the newsprint for offset printing of the present invention has a water absorption time (conforming to JAPAN TAPPI No. 32-2, 5 μl of dripping water) of 30 to 80 seconds. By setting it within this range, it is possible to prevent nepari trouble and piling in a well-balanced manner. If the water absorption time is lower than 30 seconds (the sizing degree is low), Nepari trouble and piling are liable to occur, and if it is higher than 80 seconds (the sizing degree is high), ink deposition may be deteriorated. However, the water absorption time was measured as a pretreatment of the test piece by curing at 105 ° C. for 20 minutes with a hot air dryer and then adjusting the humidity at 23 ° C. and 50%.

In the newsprint for offset printing of the present invention, the coating amount of starch is 0.2 to 1.0 g / m ² on one side, and the mass ratio of starch and surface sizing agent contained in the surface treatment agent is 99: 1 to 70. : 30. When the coating amount of starch is less than 0.2 g / m ² on one side, it tends to cause piling, and when it is more than 1.0 g / m ² , it tends to cause nappari trouble.
In addition, the mass ratio of the starch and the surface sizing agent contained in the surface treatment agent is 99: 1 to 70:30. It is easy to cause, and if there is a large amount of the surface sizing agent beyond this range, the fleshing deteriorates and causes uneven flaking.

In the present invention, it is also a preferred embodiment to use a pigment as the surface treatment agent. Examples of the pigment used include titanium dioxide, white carbon, calcium carbonate, calcined kaolin, and kaolin. However, titanium dioxide and white carbon are expensive, and calcium carbonate, calcined kaolin, and kaolin are used alone or in combination. Is preferred.
In general, it is considered that when a pigment is applied, it is more likely that pyring will occur than when it is not applied. However, as in the present invention, a very small amount of pigment is applied, and a low-viscosity starch is used. When combined with the use of olefin-based surface sizing agents, the pigment particles are exposed on the paper surface by coating the pigment, weakening the adhesion to the blanket, and suppressing papling, thereby suppressing piling. Can do. Further, as an effect of pigment coating, there is an increase in whiteness and opacity.

Here, it is preferable that the coating amount of the pigment is 0.01 to 0.3 g / m ^{2 on} one side. If the coating amount of the pigment is less than 0.01 g / m ² on one side, the effect of suppressing the above-described pigment nepari becomes low. If the coating amount of the pigment is more than 0.3 g / m ² on one side, there is a risk of causing a problem of the pile. If the coating amount of the adhesive is increased in order to prevent this, the Nepari trouble is likely to occur. It becomes difficult to balance.

In the present invention, a gate roll coater is preferably used as a coating apparatus for coating the surface treatment agent. The gate roll coater is suitable for uniformly applying a low-concentration, low-viscosity surface treatment agent, and has few troubles such as streak and good continuous operability.
When the surface treatment agent is applied using a gate roll coater, the concentration of the surface treatment agent is preferably 5 to 20%. When the concentration of the surface treatment agent is lower than 5%, the coating amount is insufficient, and when it is higher than 20%, the viscosity of the surface treatment agent is increased and uniform coating becomes difficult. The coating amount of the surface treatment agent in the gate roll coater is adjusted by the temperature, concentration, viscosity, surface ratio of the applicator roll and metering roll, and the like.

  In addition, chemicals generally used for surface treatment agents such as dispersants, pH adjusters, preservatives, and fluorescent dyes can be used as the surface treatment agent.

  In the production of newsprint for offset printing according to the present invention, the surface treatment agent is coated and dried, and then smoothed by a calendar device. As such a calendar device, commonly used calendar devices such as a chilled calendar, a super calendar, a soft calendar, and a gloss calendar can be used. As described above, the newsprint for offset printing of the present invention is obtained.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, unless otherwise indicated, the part and% in an example represent a solid content mass part and solid content mass%, respectively.
Example 1
Use 80 parts by weight of waste newspaper deinked pulp and 20 parts by weight of thermomechanical pulp as pulp raw material, add 0.3% of alkyl ketene dimer sizing agent to the pulp raw material, and adjust pH to 6.0 with sulfuric acid band. Then, 1.5% by mass of white carbon is added as a filler, paper is made with a gap former type paper machine, the following surface treatment agent is coated on both sides of the base paper with a gate roll coater, soft calendered, and a basis weight of 43 A newsprint for offset printing of 0.0 g / m ² was produced.
Surface treatment agent Low viscosity starch (trade name GRS-T120, manufactured by Oji Cornstarch Co., Ltd., B-type viscosity 6.2 mPa · s at 50 ° C., 7%)
Olefin-based surface sizing agent (trade name Polymaron OM-25, manufactured by Arakawa Chemical Industries, Ltd.)
Solid mass ratio of starch and surface sizing agent 90:10
Solid content concentration 5% (before pigment mixing)
Coating amount 0.3g / m ² (one side, excluding pigment)
Pigment coating Kaolin (trade name Capim DG, manufactured by Huber) 0.03 g / m ² (single side)

(Example 2)
A newspaper for offset printing was prepared in the same manner as in Example 1 except that the solid content concentration of the surface treatment agent was 6.5% (before pigment mixing) and the coating amount was 0.4 g / m ² (one side, excluding pigment). Manufactured.

(Example 3)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the solid content mass ratio between the surface treatment agent starch and the surface sizing agent was 73:27.

Example 4
Implemented except that the mass ratio of the surface treatment agent starch to the surface sizing agent was 95: 5, the solid content concentration was 9% (before pigment mixing), and the coating amount was 0.8 / m ² (single side, excluding pigment). In the same manner as in Example 1, newsprint for offset printing was manufactured.

(Example 5)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the amount of pigment applied was 0.01 g / m ² (one side).

(Comparative Example 1)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the surface treatment agent was coated on both sides of the base paper as follows.
Surface treatment agent Starch (trade name Ace A, manufactured by Oji Cornstarch Co., Ltd., B type viscosity 7.5 mPa · s at 50 ° C, 7%)
Olefin-based surface sizing agent (trade name Polymaron OM-25, manufactured by Arakawa Chemical Industries, Ltd.)
Solid mass ratio of starch and surface sizing agent 90:10
Solid content concentration 5%
Coating amount 0.3g / m ² (one side, excluding pigment)
Pigment coating Kaolin (trade name Capim DG, manufactured by Huber) 0.03 g / m ² (single side)

(Comparative Example 2)
Manufactures newsprint for offset printing in the same manner as in Example 1, except that the internal sizing agent was changed and 0.4% of rosin-based neutral sizing agent (trade name CC-1404, manufactured by Seiko PMC Co., Ltd.) was added. did.

(Comparative Example 3)
Newsprint paper for offset printing was produced in the same manner as in Comparative Example 1 except that no internal sizing agent was used and no pigment was applied.

(Comparative Example 4)
Manufactures newsprint for offset printing in the same manner as Comparative Example 1 except that a styrene surface sizing agent (Polymaron NS-25 manufactured by Arakawa Chemical Industries, Ltd.) was used as the surface sizing agent and no pigment was applied. did.

(Comparative Example 5)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that a styrene surface sizing agent (trade name Polymaron NS-25 manufactured by Arakawa Chemical Industries, Ltd.) was used as the surface sizing agent.

(Comparative Example 6)
Newsprint paper for offset printing was produced in the same manner as in Example 1 except that the solid content mass ratio of starch and surface sizing agent was 60:40, and no pigment was applied.

Table 1 shows the results of measuring the water absorption time and Nepari strength of the newspapers for offset printing obtained in Examples 1 to 5 and Comparative Examples 1 to 6, and the evaluation results of the pile. Each evaluation was performed as follows.
(Water absorption time)
JAPAN TAPPI Paper Pulp Test Method No. In accordance with 32-2: 2000 “Paper—Water Absorption Test Method—Part 2: Dropping Method”, an average value of 5 μl of the amount of dripped water measured twice each on the front and back sides was taken as the water absorption time. However, as a pretreatment of the test piece, it was measured by curing at 105 ° C. for 20 minutes with a hot air dryer and then adjusting the humidity at 23 ° C. and 50%.
(Measurement of Neppari strength)
Cut two newspapers for offset printing 1 inch wide x 19 cm long, float the coated surfaces on a water surface at a temperature of 20 ° C for 5 seconds, and then immediately coat the coated surfaces (wet coated surface and wet coated surface) Adhere. Subsequently, the backing sheet is overlapped on both outer sides, passed twice through a roll at a nip pressure of 40 kgf / cm, and conditioned at 23 ° C. and 50% RH for 24 hours. The peel strength was measured with a tensile tester under conditions of a pulling speed of 100 mm / min.
(Piling evaluation)
Using an ink having a tack value of 13, printing is performed with an RI printing test machine, the ink remaining on the blanket is transferred to the coated paper, the white spots are observed, and ◎ excellent, ◯ good, × bad. Rated by stage.

As shown in Table 1, according to the embodiment of the present invention, it is possible to obtain offset printing newsprint paper that has low Nepari strength and does not cause piling.
On the other hand, in Comparative Example 1, since the viscosity of starch is as high as 7.5 mPa · s, the Nepari strength is as high as 62 mN / 30 mm, and it is expected that Nepari trouble is likely to occur.
Comparative Example 2 is an example in which a rosin-based neutral sizing agent is used as the internally added sizing agent, and the Neppari strength is high. The cause of this is that the water absorption time is the same as in Example 1, but the base paper has a high degree of sizing at the time of coating with the surface treatment agent. It is thought that it remained.
Comparative Example 3 is an example in which the internal additive sizing agent was not added, and the Nepari strength was low, but the water absorption time was short, so the evaluation of piling was poor.
Comparative Example 4 is an example in which a styrene-based surface sizing agent is used as the surface sizing agent, and the Nepari strength is as high as 78 mN / 30 mm, which is likely to cause Nepari trouble.
Comparative Example 5 is an example in which a styrenic surface sizing agent was used as the surface sizing agent. Since low-viscosity starch was used, the Nepari strength was lower than that of Comparative Example 4, but increased to 54 mN / 30 mm. Expected to cause trouble.
Comparative Example 6 has a solid mass ratio of starch to the surface sizing agent of 60:40, and the ratio of the surface sizing agent is high beyond the range specified in the present invention, so the water absorption time becomes as long as 65 seconds, resulting in poor walling. Has occurred.

Claims (2)

A low-viscosity starch having a B-type viscosity of 7 mPa · s or less at 50 ° C. and 7%, an olefin-based surface sizing agent, and a surface treatment agent mainly composed of kaolin as a pigment are formed on both surfaces of a base paper containing an alkyl ketene dimer. it is coated dry coating amount of the kaolin is a single-sided 0.01 to 0.03 g / m @ 2, Neppari strength 50 mN / 30 mm or less, compliant water time (JAPAN TAPPINo.32-2, dropwise Newsprint paper for offset printing, characterized in that the amount of water is 5 μl) for 30 to 80 seconds. The content of the alkyl ketene dimer contained in the base paper is 0.01 to 0.5% by mass, the coating amount of the low-viscosity starch is 0.2 to 1.0 g / m 2 on one side, and is included in the surface treatment agent. The newsprint for offset printing according to claim 1, wherein the mass ratio of the low-viscosity starch and the olefin-based surface sizing agent is in the range of 99: 1 to 70:30.