JPH0849187A - Coated paper for offset printing - Google Patents

Abstract

PURPOSE:To obtain the coated paper for offset printing, excellent in the breaking and cracking strength and the blister resistance by adding enzyme-treated pulp to raw paper used for the coated paper. CONSTITUTION:In the coated paper used for offset printing and produced by disposing a coating layer comprising a pigment and an adhesive on raw paper obtained from cellulose pulp as a raw material, the raw paper contains enzyme- treated pulp selected from broad-leaved bleached pulp, needle-leaved bleached pulp and deinked waste paper pulp. The enzyme-treated pulp is contained in an amount of at least 35wt.% per absolutely dried pulp.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coated paper for offset printing. More specifically, the present invention relates to a coated paper for offset printing, in which the base paper used for the coated paper contains enzyme-treated pulp and which is excellent in breaking strength and blister resistance.

[0002]

2. Description of the Related Art In recent years, the importance of printed matter has been re-recognized as a medium for publication, advertisement, publicity, etc., and higher quality such as visualization and colorization of printed matter has been promoted. The demand for coated paper manufactured by coating a coating liquid consisting of on paper is increasing, and in particular, the demand for coated paper for offset printing, which is the most widely used for multicolor printing, is remarkable. .

[0003] Offset printing is a method in which printing is not performed directly on a plate on paper, but is first transferred to a rubber surface called a blanket, then printed from the blanket on paper and dried. Conventionally, as raw materials of paper before coating of offset printing coated paper (hereinafter referred to as base paper), softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP),
Pulp and the like, which is produced by disintegrating coated broke generated from the manufacturing process of coated paper, has been used, but recently, cost reduction,
High-yield pulp and deinked waste paper pulp made from waste paper have come to be used for reasons such as improvement of opacity and recycling of pulp.

A paper strengthening agent, a sizing agent and the like are used for the base paper depending on the intended use of the coated paper. For example, cationized starch, polyacrylamide, polyvinyl alcohol, etc. are used for the purpose of improving the strength of the base paper such as the interlaminar strength, and alkyl ketene dimer, alkenyl succinic anhydride-based size, rosin-based are used for improving the size property. Size, sulfuric acid band, etc. are used. Furthermore, the surface of the base paper is coated with oxidized starch, polyvinyl alcohol, a surface sizing agent and the like by using a device such as a two roll size press or a Gero roll coater.

In offset printing, after printing water and ink on the surface of the coated paper, the paper is rapidly dried at a temperature of 115 to 125 ° C. to obtain a printed paper, which is contained in the coated paper at that time. Also, there is a problem that the water evaporates and the coating layer swells, that is, "blister" occurs, and the value of the printing paper is remarkably reduced.

[0006] In order to improve the blister resistance of the coated paper for offset printing, studies have been conventionally made to increase the strength in the thickness direction of the coated paper, that is, the interlayer strength. The interlaminar strength of the coated paper is generally adjusted by increasing or decreasing the addition of a paper strengthening agent, especially a cationized starch, in the paper making process. When the rice basis weight of the base paper is increased, the absolute amount of water is also increased accordingly, blister is more likely to occur, and the addition rate of the cationic starch added to the base paper is increased.

However, when cationized starch is used to increase the interlaminar strength of the base paper and improve the blister resistance, the base paper becomes hard and the breaking strength is reduced. The offset printing paper is often used as a product such as a cover of a book, a magazine cover, or a base paper of an art printing book for a product, and in this case, there is a problem that breakage occurs from a crease and product value is reduced. On the other hand, even if an attempt is made to improve the interlaminar strength of the base paper by using other paper-strengthening agents without using the cationized starch, the paper becomes harder to some extent and the problem of resistance to crease cracking occurs. Occurs.

On the other hand, in recent years, a technique has been proposed in which a lignocellulosic material and a fiber obtained by processing the lignocellulosic material (for example, a wood fiber) are treated with an enzyme to modify them. For example, a method for reducing power consumption in a refiner in a step of preparing a papermaking raw material by treating pulp fibers composed of hemicellulose and cellulose with an enzyme (Japanese Patent Laid-Open No. 60-126395, Japanese Patent Laid-Open No. 3-174).
079), wood logs or wood chips are ground or defibrated and treated with an enzyme having a pectin-degrading activity to produce pulp and paper with higher whiteness (JP-A-2-11).
No. 8191), a method of treating broad-leaved pulp from southern timber with an enzyme having a decomposition activity for filter paper to eliminate the vessel picking trouble of the paper and improve smoothness and tensile strength (Japanese Patent Laid-Open No. 63-135597). Japanese Patent Laid-Open No. 9-9299), a method of adding a polysaccharide hydrolase in a used paper recycling process to improve deinking and drainage of used paper pulp (JP-A-59-9299).
JP-A-63-59494, JP-A-63-59494
145495, Tappi, Volume 72 (6), 18
7 (1989)), a method of using an enzyme for defibrating waste paper (JP-A-3-228685), a method of applying the enzyme to bleaching pulp (JP-A-2-293486), and the like. .

[0009]

SUMMARY OF THE INVENTION In view of the above situation, the inventors of the present invention have aimed to improve the quality of coated paper, and in particular to improve the blister resistance and crease resistance of offset coated paper. We have conducted intensive research on the properties of enzyme-treated pulp that affects quality and the technology for obtaining the pulp. As a result, focusing on the fact that the pulp treated with the enzyme having the degradability of the filter paper significantly improves the interlaminar strength of the paper, the pulp selected from NBKP, LBKP and deinked waste paper pulp is treated with the enzyme to give a specific amount thereof. The present invention has been completed by finding that the use of a paper containing the above as a base paper for coating can significantly improve the blister resistance and crease resistance of the offset printing coated paper.

An object of the present invention is to provide a coated paper for offset printing which has improved blister resistance and crease resistance.

[0011]

The first object of the present invention is to provide a coated paper for offset printing in which a coating layer comprising a pigment and an adhesive is provided on a base paper obtained by making paper from cellulose pulp as a raw material. The coated paper for offset printing is characterized in that the base paper contains an enzyme-treated pulp selected from a bleached hardwood pulp, a bleached softwood pulp, and a deinked waste paper pulp. A second aspect of the present invention is the coated paper for offset printing according to the first aspect of the present invention, characterized in that the base paper contains at least 35% by weight of enzyme-treated pulp per absolute dry pulp.

The hardwood bleached pulp and softwood bleached pulp as the lignocellulosic pulp of the present invention are obtained by pulping wood chips from hardwood and softwood by a chemical pulping method such as the known kraft cooking method, and then bleaching with oxygen. Alternatively, without bleaching with oxygen, CEHD, CE-
H-D-E-D, C-E-D-E-D, C-E-H-P
-D (where C is a chlorine stage, E is a caustic soda extraction stage containing a combination of oxygen, H is a hypochlorite stage, D is a chlorine dioxide stage,
A bleached pulp that has been subjected to known multi-stage bleaching such as P represents a hydrogen peroxide stage) and bleached to a Hunter whiteness of 80 to 90% is preferably used. Further, as other lignocellulosic pulp, deinking obtained by defibrating and deinking high-quality waste paper such as computer paper, facsimile paper, etc. and newspaper and magazine waste paper, and further bleaching if necessary Waste paper pulp is used for the present invention.

In the present invention, the pulp is subjected to an enzyme treatment to be modified, and the pulp is used to produce a base paper for offset printing coating. The mechanism of paper produced using this enzyme-treated pulp has not been fully clarified, but the adhesion and entanglement of the fibers in the paper layer are improved, and the fibers themselves become softer, which results in the interlayer strength of the paper. And crease resistance (folding resistance) are improved, and by applying an offset printing paint consisting of pigments and adhesives on this paper to make coated paper, a coated paper with excellent blister resistance can be obtained. .

The enzyme used for the present invention may be any enzyme having a filter paper-decomposing activity that contributes to improving the interlayer strength of paper, and examples thereof include cellulase and hemicellulase. . About this enzyme, it can be used alone or in combination by selecting from various cellulase having filter paper degrading activity, hemicellulase, etc., and further used as a polysaccharide degrading enzyme, a lignin degrading enzyme, a lipolytic enzyme, a protein degrading enzyme, etc. It is also possible to use them in combination.

The above-mentioned activity for degrading filter paper is as described in Biotechnol. Bioe.
nng. Symp. 6, 21 to 33 (1976). That is, for a tester having a diameter of 18 mm and a length of 180 mm, 1 ml of 50 mM citrate buffer solution (pH 4.8) and 0.5 ml of enzyme solution 50 mg of filter paper (whatman No. 1,
(1 × 6 cm) is put into a coil, reacted at 50 ° C. for 1 hour, 3 ml of 3,5-dinitrosalicylic acid reagent is added, heated in a boiling bath for 5 minutes, and then cooled (cooled with water). or,
A calibration curve for the amount of light absorption and the amount of glucose is created in advance, and the amount of light absorption is converted to the amount of glucose from this calibration curve. The definition of filter paper degrading activity is to display the amount of enzyme that produces a reducing sugar corresponding to 1 μmol of glucose per minute as one unit, and the filter paper degrading activity of the enzyme is obtained from the following formula. FPU / enzyme g (filter paper degrading activity) = mg glucose × 1
/0.13 × 1/60 × × Dilution ratio However, FPU is the Filter Paper Unit
Is an abbreviation for

The enzyme treatment conditions are as follows. The amount of enzyme added is 0.001 to 5.0 per 1 g of pulp
FPU, preferably 0.005 to 2 FPU. If the addition amount is 0.001 FPU or less, the desired reforming effect cannot be obtained, and if it is 5.0 FPU or more, the pulp yield is significantly reduced, which is not suitable. The treatment time is 0.1 to 48 hours, preferably 0.5 to 24 hours. When the treatment time is less than 0.1 hours, the desired modifying effect cannot be obtained, and when the treatment time is 48 hours or more, the obtained effect reaches the ceiling. Is not suitable. The pulp concentration is
Any concentration may be used as long as the enzyme and pulp can be uniformly mixed, but the concentration is 0.5 to 20% by weight, preferably 2 to 15% by weight. The pH during the treatment depends on the enzyme used, but is preferably in the range of 3 to 11. The temperature during processing is
Although it depends on the enzyme used, it is appropriately selected and used in the range of 10 to 80 ° C. The reaction vessel which is subjected to the enzyme treatment under the above-mentioned enzyme treatment conditions may be a well-known container such as a chest, a tank, or a tower, and the enzyme treatment is performed during continuous transfer of pulp or in a batch system. In the enzyme treatment, all of the pulp used may be treated with an enzyme, or the pulp treated with the enzyme and the pulp not treated with the enzyme may be appropriately mixed and used.

For enzyme treatment of pulp, it is important to mix the pulp and enzyme uniformly and sufficiently. When the pulp is pumped, a method of adding the enzyme to the suction port of the pump and mixing the mixture, using a static mixer is used. There is no particular limitation as long as the pulp and the enzyme can be sufficiently mixed, such as a method of mixing the pulp and the enzyme, a method of adding the enzyme before the refiner when the pulp is beaten, and a method of sufficiently mixing the pulp and the enzyme.

Besides the enzyme-treated hardwood bleached pulp, softwood bleached pulp and deinked waste paper pulp, of course, the above-mentioned non-enzymatically treated pulp, stone ground pulp (SGP),
High yield pulp such as pressure stone ground pulp (PGW), thermomechanical pulp (TMP) and refiner ground pulp (RGP) may be used in combination depending on the quality design of the coated paper. In this case, the total content of enzyme-treated hardwood pulp, softwood pulp and deinked waste paper pulp must be 35% by weight or more based on the weight of absolutely dry pulp,
The use ratio of the enzyme-treated pulp is appropriately determined depending on the use of the coated paper. If the content of the enzyme pulp is less than 35% by weight, the effect is not sufficiently exhibited, and it becomes difficult to obtain excellent interlayer strength and flexibility.

The base paper used in the coated paper of the present invention is produced by a known paper-making method using a papermaking chemical such as a filler, a sizing agent, a retention aid, and a paper-strengthening agent in combination with the above-mentioned raw materials. Acid paper that is made at a pH of around 4.5 using
Adjust pH to 6 with alkali with or without sulfuric acid band
It may be a so-called neutral paper which is produced in a weakly acidic to weakly alkaline region of -9. The basis weight of the base paper is 20-4
It is appropriately selected from the range of 00 g / m ² as necessary.

In the present invention, a paint comprising a known coating pigment such as kaolin and calcium carbonate and an adhesive such as starch and styrene-butadiene rubber latex on the base paper obtained as described above is known. After coating with a blade coater, roll coater, etc., on-machine or off-machine, in a single step or in several steps in a number of 5 to 30 g / m ² per side and dried to a moisture content of 3 to 8% , And
A surface treatment is applied in a finishing device such as a percalender to finish the coated paper with offset suitability.

[0021]

The present invention will be described in more detail with reference to the following examples, but of course the present invention is not limited thereto. In the following,% means% by weight.

The bleached hardwood pulp used in the present invention (LBK
P) is a mixed chip consisting of 60% domestic hardwood, 25% older, and 15% Tasmanian eucalyptus, kraft cooked in a Kamiya continuous digester to pulp, then oxygen bleaching, C (chlorine) -E / o (caustic soda). / Oxygen) -H (sodium hypochlorite) -D (chlorine dioxide) is a multi-stage bleached Hunter whiteness pulp of 84.5%. Softwood bleached pulp (NBKP) is Douglas fir 15%, domestic Mixed chips consisting of 85% pine pine are kraft cooked in a Kamiya continuous digester to pulp, then oxygen bleaching, CE / o
-H-D multi-bleached Hunter whiteness 84.5%
The deinked waste paper pulp (DIP) is a pulp of the newspaper, and used to disintegrate newspaper and magazine waste paper with a fiber flow pulper.
Deinked to remove foreign matter, and then bleached with 1-step hydrogen peroxide to obtain a freeness of 190 ml CSF, Hunter whiteness of 7
It is 0% pulp. Furthermore, the freeness is 35mlCS
A high-yield pulp (SGP) having a 150 mesh passing amount of 45% in the pulp sieving test (JIS P 8207) in F was prepared.

LBKP, NBKP and DIP each have a degrading activity of 106 FPU along with dilution water in the transport screw before being put into separate finished towers.
/ Enzyme g enzyme (Godou Shusei Co., Ltd., trade name: Vesselex) is added at 0.1 FPU per 1 g of absolutely dry pulp, and it is sent while mixing with a medium-concentration pulp transfer pump (Kamiya, MC mixer), and the completion tower Each of the pulps was separately treated with an enzyme inside. The enzyme treatment condition is that the pH is 5.
1, the temperature was 45 ° C., the pulp concentration was 9%, and the treatment time was 4 hours.

In the examples and comparative examples of the present invention, a coating solution (55% concentration) having the composition shown below was coated on both sides of the base paper with a 7 g / m ² blade coater per side, and air was applied at a temperature of 150 ° C. After drying with a foil dryer to a water content of 5.5%, super calender treatment was performed. Coating composition Kaolin (EMC, HT clay) 60% Heavy calcium carbonate (in-house crushed, average particle size 1.2 μm) 40% Per dry weight pigment oxidized starch (Oji Constarch, Oji Ace) 2 0.0% Styrene-butadiene latex 12.0% (JSR2630, manufactured by Japan Synthetic Rubber Co., Ltd.)

Example 1 Enzyme-treated NBKP (hereinafter referred to as “enzyme NBKP”) beaten to a freeness of 430 ml CSF and 400 ml C
Enzyme-treated LBKP beaten to SF (hereinafter referred to as enzyme LB
KP) was prepared for each. Enzyme treated DIP
(Hereinafter referred to as enzyme DIP) was used as it was without beating. Enzyme NBKP: Enzyme LBKP: Enzyme DIP
Is mixed at a ratio of 30:50:20, and to this, 1.3% of cationized starch (Kate F manufactured by Oji National Co., Ltd.) and polyacrylamide (manufactured by Harima Chemicals Co., Ltd.
Hermide EX-360) 0.4%, sulfuric acid band 0.5
%, Yield improver (NR-11LH manufactured by Kyoritsu Organic Co., Ltd.)
0.02% was added to make paper with a Fourdrinier multi-cylinder dryer type paper machine, 2.5 g / m ² of oxidized starch (Oji Ace A manufactured by Oji Constarch Co., Ltd.) was applied and dried with a ^two- roll size press, and A coating base paper having a rice basis weight of 50 g / m ² and a water content of 5.5% was produced. The above coating solution was applied onto this base paper to produce a coated paper for offset printing. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Test Method (1) Interlayer Strength Japanese Tappi No. It measured by the following method according to 19-77. Adhesive tape on both sides of the base paper (German Beiersdorf, Tesa No. 4863, width 38 mm)
Evenly pressure-bonded, and cut into a strip shape with a width of 25 mm, then pull the adhesive tape on both sides of the strip with a Tensilon universal tensile tester (manufactured by Toyo Baldwin),
The tensile strength (g) required for peeling the paper layer of the base paper was measured, and the magnitude of the value was evaluated.

(2) Blister resistance A RI tester manufactured by Akira Seisakusho kneads 1 ml of offset ink and prints on both sides of the coated paper. Immediately after that, the printing surface is heated by a hot press at 250 ° C. to generate on the printing surface. The occurrence of blister was observed visually and evaluated as follows. ⊚: No blister is generated, which is extremely excellent. ◯: Blister is slightly generated, and it is slightly excellent. Δ: Some blister is generated, but there is no problem in practical use and it is normal. ×: Blistering occurred considerably and there was a problem in practical use,
Somewhat inferior. XX: Blisters are severely generated, cannot be put to practical use, and are extremely inferior. (3) Folding strength The coated paper was cut in the flow direction, and the folding strength was measured according to JIS P 8115, which was used as an index of the breaking crack strength.

Example 2 Enzyme NBKP: Enzyme LBK after adjusting the pulp freeness
P: Enzyme DIP: SGP = 25: 25: 25: 25 except that the pulp mixed was used, the base paper for coating was manufactured in the same manner as in Example 1, and the base paper for offset printing was coated using this base paper. Crafted paper was manufactured. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Example 3 The freeness of the enzyme NBKP was adjusted to 430 ml CSF, LBK.
The freeness of P was adjusted to 400 ml CSF, and the enzyme NB
A base paper for coating was manufactured in the same manner as in Example 1 except that pulp mixed at a ratio of KP: LBKP = 40: 60 was used, and a base paper for offset printing was manufactured using this base paper. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Example 4 Freeness of NBKP was 430 ml CSF, enzyme LBK
Adjust the freeness of P to 400 ml CSF, NBK
A base paper for coating was manufactured in the same manner as in Example 1 except that pulp mixed at a ratio of P: enzyme LBKP = 40: 60 was used, and the base paper for offset printing was manufactured using this base paper. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Comparative Example 1 Enzyme NBKP, enzyme LBKP, enzyme D in Example 1
NBKP, LBKP not treated with enzyme in place of IP,
A base paper for coating was manufactured in the same manner as in Example 1 except that DIP was used, and a base paper for offset printing was manufactured using this base paper. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Comparative Example 2 Enzyme NBKP, enzyme LBKP, enzyme D in Example 2
NBKP, LBKP not treated with enzyme in place of IP,
A base paper for coating was manufactured in the same manner as in Example 2 except that DIP was used, and a base paper for offset printing was manufactured using this base paper. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Comparative Example 3 A base paper for coating was produced in the same manner as in Example 3 except that NBKP which had not been treated with an enzyme was used in place of the enzyme NBKP, and the base paper was used for offset printing. Crafted paper was manufactured. In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

Comparative Example 4 The freeness of the enzyme NBKP was 430 ml CSF, NBK
The freeness of P was adjusted to 430 ml CSF and the freeness of LBKP was adjusted to 400 ml CSF, and the enzyme NBKP: NB
A base paper for coating was manufactured in the same manner as in Example 1 except that pulp mixed at a ratio of KP: LBKP = 25: 15: 60 was used, and a base paper for offset printing was manufactured using this base paper. . In order to evaluate the quality, the interlaminar strength of the base paper for coating was measured by the following test method, and further the blister resistance and folding strength of the coated paper were tested. The obtained results are shown in Table 1.

[0035]

[Table 1]

As can be seen from Table 1, the present invention (Examples 1 to 1)
4) and the conventional method (Comparative Examples 1 to 3) for comparing offset printing coated papers with each other, the coated paper of the present invention is The interlayer strength is high in all cases, and the folding strength and blistering resistance are remarkably improved. When the amount of enzyme-treated pulp used is small, it is difficult to obtain the desired effect (Comparative Example 4).

[0037]

As described above, according to the present invention, by using a base paper containing a specific amount of enzyme-treated pulp, the interlaminar strength is remarkably high, and the breaking crack strength (folding strength) and blister resistance are improved. The effect of providing an excellent coated paper for offset printing is exerted.

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Claims (2)

[Claims] 1. A coated paper for offset printing, comprising a base paper obtained by making a paper from cellulose pulp as a raw material, and a coating layer comprising a pigment and an adhesive on the base paper, wherein the base paper is a hardwood bleached pulp or a softwood bleached pulp. And a coated paper for offset printing, which contains an enzyme-treated pulp selected from deinked waste paper pulp. 2. The coated paper for offset printing according to claim 1, wherein the base paper contains at least 35% by weight of enzyme-treated pulp per absolute dry pulp.