JP3518290B2 - Newsprint paper for offset printing - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION The present invention relates to newsprint.
Excellent print workability and excellent color print quality
The present invention relates to offset printing newsprint. [0002] 2. Description of the Related Art In recent years, newspaper printing has been performed in a conventional letterpress printing method.
Is rapidly progressing to offset printing.
Currently, more than 80% of newspaper printing is based on offset printing.
It is said that. Offset printing is usually called PS version
Create a printing plate and supply it with dampening water and ink.
It is a method to do. The printing plate is a lithographic printing plate.
The surface is treated to give a lipophilic surface, while the non-
Treated to an aqueous surface. Wet this plate
When water and ink are supplied, the ink is
Area is covered with water.
Printing is performed by transferring the ink to paper through the ket. In this offset printing, a relatively tacky
Strong paper surface strength to use strong ink
Is required. Also, to treat the paper surface with dampening water
Has a surface with low surface strength or low water resistance
When paper is used, paper dust may accumulate on the blanket,
When mixed with ink, so-called blurring occurs on the printed surface.
Troubles such as wobbling occur. Also, light weight of newsprint
Demand for high opacity after printing is increasing
White carbon or acid to increase paper opacity.
Inorganic pigments such as titanium oxide and talc are often used as fillers in papermaking.
It has come to be used frequently. These inorganic pigments
Easily seeps out of the paper layer by dampening water when printing
Easy to use, the main ingredient of paper powder to be piled on blanket
One. [0004] In such a problem at the time of offset printing,
In order to deal with this, starch and newspapers have been
Polyvinyl alcohol, polyacrylamide, etc.
It has been generally practiced to apply a high polymer material. This
These surface treatment agents improve the strength of the paper surface and
Fine fibers and fillers can be strongly adhered to paper
However, when the coating amount increases, the paper surface
Adhesion increases, sticks to blanket during printing, breaks
Inducing paper or even increasing the amount of these surface treatments
Use is to suppress the penetration of the ink to the paper surface,
Ink absorption unevenness caused by coating unevenness in color printing
(Color unevenness on the printed surface)
I have. [0005] To suppress surface tackiness and increase surface strength
For this purpose, various methods have been conventionally proposed. For example, specific
Of polyacrylamide compound on the surface
Enhance the strength of the paper surface and further reduce polyhydric aldehydes
A method for enhancing surface water resistance by using together (Japanese Unexamined Patent Application Publication No.
JP-A-8-13384) and polyvinyl alcohol
Blocks of ethylene oxide and propylene oxide
By applying the composition containing the copolymer, the surface
For improving the noise, surface strength and surface tackiness
No. 5-59689) has been proposed,
It is not always enough to balance the relaxation of the property and the surface strength
And ink absorption on color printing surfaces
The fact that unevenness has not yet been improved
is there. In addition, rosin emulsion sizing agents and the like
Use a sizing agent to increase the size of the paper surface and
To reduce the penetration of dampening water into the paper layer during printing
Conventionally, the generation of paper dust has been suppressed,
These internal sizing agents are used in high-speed paper machines such as newspaper paper machines.
Is easy to induce trouble due to foaming in white water system. Ma
In addition, newsprint is a ground paper that does not easily produce a size effect.
Because lumps are often used as raw materials,
When a retention aid is used in combination with
To reduce the whiteness of newsprint.
It has such difficulties. [0007] SUMMARY OF THE INVENTION The present inventors have developed an excellent
Offset with offset printing workability and print (finished) quality
Dedicated research on newsprint for set printing
Was. As a result, the present invention provides a
The initial contact angle on the paper surface
To make the blanket paper powder pile
Offset with no color and excellent color printability
The purpose of the present invention is to provide newsprint for paper printing. [0008] SUMMARY OF THE INVENTION According to the present invention, a table is provided on a base paper.
For offset printing newspapers coated with surface treatment agent and dried
On paper,The surface treatment agent is a styrene monomer containing 40
Surface sizing agent which is a water-soluble polymer contained in an amount of up to 80% by weight
And an aqueous composition containing starch and a surface sizing agent
0.03 to 0.1 g / m per side in solid content
^Two AndThe contact angle between the newsprint and water (water droplets
1 second after falling) is more than 90 degrees
Offset printing newsprint paper. [0009] DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, conventionally,
Starch and polyvinyl alcohol are used for newsprint for set printing.
Or polyacrylamide on the paper surface
This is commonly done. These surface treatment agents
Although slippage is effective in suppressing paper dust,
Increasing the amount will cause uneven ink absorption and viscosity in color printing.
Bra during printing based on the adhesiveness (hereinafter referred to as Nepari)
Problems such as sticking to the blanket occur. A feature of the present invention is the contact angle between the paper surface and water.
(Value 1 second after dropping on paper) is specified as 90 degrees or more
There. Specifying such a contact angle is effective in reducing paper dust.
Reasons for contributing to improved color printability at the same time
Is not always clear, but is speculated as follows:
You. That is, dampening applied to the paper surface during offset printing
Water easily penetrates into the paper layer and has good wettability with pulp fibers.
When bleeding, bleeding to the outside with fine fibers and internal filler in the paper layer
The fine raw material that exudes is
It is expected to be the basis for Traditionally, newsprint has been
Because of the pulp (paper layer) composition, it has strong water absorption,
It is easy to be triggered. So you can
As much as possible to prevent the paper layer from getting wet with water.
As a result, it is necessary to suppress the emergence of fine raw materials by water.
It is estimated that paper dust etc. will be reduced or eliminated
Is done. Therefore, the present inventors have tried to suppress the water absorption of the paper layer.
Various investigations were conducted. As a result, on newsprint
The contact angle 1 second after dropping water is 90 degrees or more.
Or adjusted to be at least 95 degrees, relatively water
By using paper that is difficult to get wet,
The bleeding action of fibers and internal fillers is reduced, and paper dust is generated.
Is greatly reduced, while on the other hand
Is improved, ink inking property is improved, and as a result
It can be seen that ink absorption unevenness is reduced or eliminated
Ming has been completed. The upper limit of the contact angle
Is not particularly limited, but practically 110 degrees
Rank is enough. Increasing the contact angle beyond that is
Large amounts of molecular surface sizing agents need to be used,
As a result, the appearance of the paper fluctuates and adverse effects on the suitability for offset printing
Is not preferred because Here, the contact angle of the sheet has a large value.
Means that it is hard to get wet with water. Generally, paper water
Contact angle according to TAPPI T-458-84
Measured. In this method, a water drop is dropped on the paper and then
The measurement is performed after 5 seconds or 1 minute. I
However, in actual offset printing, the dampening solution
Until it comes into contact with the blanket and paper
It is instantaneous, so wet in such a short time
Was measured according to the above-mentioned TAPPI T-458-84 method.
It cannot be reproduced well with a contact angle that is too high. Therefore, the present inventors
Further studied the suitability for water wetting. As a result,
Contact angle meter [Dynamic absorber
Option Tester DAT1100 (FIBRO)
The contact angle was measured one second after water was dropped onto the paper using
By adopting this value, the actual offset printing
And that there is an extremely high correlation between the contact angle and paper dust generation.
And found. In addition, about measurement less than one second
Indicates an unstable shape due to the impact of water dropped on the paper.
However, satisfactory measurement could not be performed. The contact angle measured by the contact angle measuring device is 90 degrees.
The method of adjusting the paper so that
Although not specified, rosin conventionally used
Using only the internal sizing agent such as the size, etc.
Can be made hard to wet, but the table desired by the present invention
Strong water repellency of the surface cannot be obtained. On the other hand,
The effect of using relatively large surface sizing agents
The contact angle of the surface can be increased effectively. In particular, the monomer
-Use a surface sizing agent that contains a large amount of styrene
The desired effect can be obtained by using. The surface treating agent used in the present invention comprises
With an agentstarchConsisting of, for example, surface size
As an agentIsTylene / acrylic acid / acrylate
Copolymer, styrene / maleic acid ester copolymer, etc.
Known and public ones are exemplified,starchFor example,
Starch, oxidized starch, dialdehyde starch, phosphoric acid modified
Starch, cationized starchThroatIs exemplified. The present invention
In order to obtain a high contact angle as specified in
/ Acrylic ester copolymers are preferably used. [0015] The amount of the surface sizing agent added in the present invention
It is particularly limited as long as the specified contact angle can be obtained.
Although not a thing, usually 0.02 to 0.2 g / m^Two, Preferred
Or 0.03 to 0.1 g / m^TwoIs added within the range.
Incidentally, the addition amount is 0.02 g / m^TwoIf less than the book
It is difficult to obtain the high contact angle desired by the invention,
0.2g / m^TwoExceeds the surface strength, the surface
At times, troubles such as picking may occur. As a more preferred embodiment, the surface
As a component of the sizing agent (water-soluble copolymer), styrene
Nomer is 40 to 80 weight in solid content ratio with respect to all components.
%, Preferably 40 to 60% by weight
The use of a hydrophilic polymer makes it possible to achieve
This is preferable because a higher contact angle can be obtained. The reason
The reason is not always clear, but as follows:
Presumed. That is, the ratio of the styrene monomer which is hydrophobic
By increasing the rate, against water (fountain solution during printing)
Poor wetting of the paper surface, resulting in high contact angles
It seems to be. In addition, the ratio is less than 40% by weight.
In this case, it is difficult to obtain a high contact angle, while 80% by weight
Beyond that, the contact angle will be very high, but on the other hand
Concerns about reduced ink acceptability and color printability
The quality and quality of newsprint.
There is a possibility that. The surface treating agent thus obtained has a solid concentration
Adjusted to 1-10% by weight and applied to newsprint base paper
You. The coating amount in that case is usually the dry weight per one side
0.05-1 g / m^Two, Preferably 0.1 to 0.5 g /
m^TwoIs applied on both sides. By the way, the application amount is 0.
05g / m^TwoIf less, sufficient surface strength cannot be obtained.
1g / m^TwoBeyond, the Nepali strength increases
Cause troubles such as sticking to blanket
There is a fear. In addition, coating equipment for applying the surface treatment agent to the base paper
For example, size press, blade metering
Size press, rod metering size press, gate
Roll coater, blade coater, bar coater, b
General, such as blade coater and air knife coater
A publicly known and used device is appropriately used. And in general
After coating, the surface is smoothed by calendering
But in that case, machine calendar with double-sided metal roll
Finishing and soft curry consisting of metal roll and elastic roll
Under finish is performed. As the base paper for newsprint according to the present invention,
Chemical pulp (NBKP, LBKP, etc.)
Mechanical pulp (GP, CGP, RGP, PGW, TMP
Etc.), used paper pulp (DIP etc.) alone or in any ratio
Used in a mixed ratio. In addition, white carbon,
Clay, amorphous silica, talc, titanium oxide, calcium carbonate
A filler for papermaking such as calcium is added during papermaking. Also,
Other than paper strength agent, retention agent, reinforced rosin size
Agents, sizing agents such as emulsion sizing agents, waterproofing agents, purple
Appropriately added publicly known official papermaking chemicals such as external line inhibitors
Is done. Then, the paper is generally made on a publicly known public paper machine.
You. The basis weight of the base paper is not particularly limited.
Is generally 35 to 50 g / m^TwoIt is about. [0020] The present invention will now be described in more detail with reference to the following examples.
I will tell. Of course, the present invention is not limited to them.
No. Parts and percentages in the examples are those unless otherwise specified.
The parts by weight and% by weight are shown. Embodiment 1 (Making of base paper) 10 parts of softwood kraft pulp, thermome
40 parts of cannical pulp, 20 parts of ground pulp, and
Mixed with 30 parts of deinked waste paper pulp and refiner
Disintegrate and freeness 120ml (csf / Canadian standard file)
Pulp slurry (paper material)
And added 1% of white carbon per absolutely dry pulp
After that, the paper is made by Fourdrinier paper machine,^Twoof
Newspaper base paper was obtained. (Production of surface sizing agent) Stirrer, cooling pipe,
Flask with dropping funnel, nitrogen inlet tube and thermometer
45 parts of styrene, 10 parts of n-butyl acrylate,
45 parts of tacrylic acid, 35 parts of isopropyl alcohol,
35 parts of water and 2,2'-azobisui as a polymerization initiator
Charge 5 parts of sobutyronitrile and stir under nitrogen flow
And maintained at 80-85 ° C for 5 hours. Then, a predetermined amount of water
And neutralized with 28% aqueous ammonia to obtain a surface sizing agent
Was. Its appearance is a slightly cloudy liquid, apparent at 25 ° C.
Has a viscosity of about 1000 cps, a non-volatile content of 20.5%, and
And pH was 9.0. (Application of surface treatment agent) Water-soluble polymer adhesive
Oxidized starch (trade name: Ace A / Oji Corns)
100 parts of the surface sizing agent obtained above,
After mixing and dilution, a surface treatment agent having a solid content of 4% was obtained. this
The surface treating agent thus obtained was applied to the above-described base paper for newspaper (Yonetsubo 4).
2g / m^TwoUse gate roll coater on both sides
0.3 g / m per side in dry weight^Two(Oxidized denatured precipitate
Powder = 0.21 g / m^Two, Surface sizing agent = 0.09 g / m
^Two) Is applied on both sides and dried, then metal roll
/ 150k linear pressure on machine calendar made of metal rolls
Offset printing with 1 nip feed under g / cm conditions
Newspaper was obtained. Embodiment 2 In Example 1, the preparation of the surface sizing agent
65 parts by weight of the len monomer and methacrylic acid
Is the same as Example 1 except that
Newspaper for offset printing was obtained by the method. This surface size
The appearance of the agent is a slightly cloudy liquid, and the apparent viscosity at 25 ° C is about
1500 cps, nonvolatile content 20.5%, pH 9.0
Met. Embodiment 3 In the preparation of the surface sizing agent of Example 1,
85 parts of mer and 5 parts of n-butyl acrylate
Parts and methacrylic acid were changed to 10 parts, respectively.
Except for offset printing for newspapers in the same manner as in Example 1.
I got the paper. The appearance of this surface sizing agent is a slightly cloudy liquid,
The apparent viscosity at 25 ° C is about 1400 cps,
The pH was 20.5% and the pH was 9.0. Embodiment 4 In the preparation of the surface treatment agent of Example 1, oxidized modified starch
(Product name: Ace A / Oji Cornstarch) 100
Parts, and the surface sizing agent was changed to 100 parts,
Newspaper for offset printing was obtained in the same manner as in Example 1.
Was. In this case, the amount of the surface treatment agent applied is a dry weight.
0.2 g / m per side^Two(Oxidized modified starch = 0.1 g /
m^Two, Surface sizing agent = 0.1 g / m^Two)Met. Embodiment 5 In the preparation of the surface treatment agent of Example 1, the water-soluble polymer
Oxidized modified starch (trade name: Ace C / Ojiko)
100 parts, surface support used in Example 1.
Mix 40 parts of an oiling agent, dilute with water and apply a surface treatment of 4% solids.
A physical agent was obtained. Newspaper using this surface treatment agent in Example 1
Use a gate roll coater on the base paper to
0.2g / m in dry weight^Two(Oxidized modified starch = 0.1
4g / m ^Two, Surface sizing agent = 0.06 g / m^Two) Becomes
Roll on both sides after coating and drying on both sides
130kg / linear pressure on machine calender consisting of rolls
1 nip paper passing under the condition of cm
I got a question paper. [0028] Example6 15 parts of softwood kraft pulp, thermomechanical pulp
35 parts, ground pulp 10 parts, deinked waste paper pulp 40
Parts, mix with a refiner and freeness
Prepare 150ml (csf / Canadian Standard Freeness)
Talc was applied as a filler to the dried pulp slurry.
1%, and make a paper with Fourdrinier paper machine.
/ M^TwoNewspaper base paper was obtained. Others using this base paper
Prepares newsprint for offset printing in the same manner as in Example 1.
Obtained. Comparative Example 1 In the preparation of the surface treatment agent of Example 1, the surface sizing agent was used.
Offset was performed in the same manner as in Example 1 except that no addition was made.
Newsprint paper for printing was obtained. Comparative Example 2 The surface sizing agent contained in the surface treating agent of Example 1
And the styrene monomer blending number is 20 parts,
15 parts of n-butyl acid and 65 parts of methacrylic acid
Outside, newspaper printing for offset printing in the same manner as in Example 1.
I got the paper. The appearance of this surface sizing agent is a slightly cloudy liquid.
The apparent viscosity at 25 ° C is about 800 cps,
Was 20.0% and pH was 9.0. Comparative Example 3 In the preparation of the surface treatment agent of Example 1, the surface sizing agent
After the addition amount was changed to 5 parts per 100 parts of oxidized modified starch
Outside, newsprint for offset printing in the same manner as in Example 1.
Got. At this time, the applied amount of the surface treatment agent
0.3 g / m per surface^Two(Oxidized starch = 0.286 g
/ M^Two, Surface sizing agent = 0.014 g / m^Two)
Was. Comparative Example 4 In Example 5, the amount of the surface sizing agent added was
Example 5 except that the powder was changed to 10 parts for 100 parts.
Newsprint paper for offset printing was obtained in the same manner. At this time
The amount of the surface treatment agent applied is 0.2 g per side by dry weight
/ M^Two(Oxidized modified starch = 0.182 g / m^Two， Surface rhino
Solution = 0.018 g / m^Two)Met. [0034] In the thus obtained Examples and Comparative Examples,
In newsprint for set printing, the quality
The results are shown in Table 1. [Ink absorption unevenness] Offset printing machine (small
Mori System C-20), 4 color printing
And visually check the ink density unevenness of the indigo / red super-colored areas
Was determined. A: A uniform and clear image without any ink density unevenness. ：: A uniform image with almost no ink density unevenness. Δ: An uneven image of ink density was observed, and the image was slightly uneven. X: An image in which unevenness in ink density is apparent and is non-uniform. [Blanket Paper Powder Piling] Offset
Printer (Komori SYSTEM C-20)
After printing four copies and printing 5,000 copies,
Visually determine the degree of paper dust accumulation on the non-image area of the blanket
did. ◎: No generation of paper dust was observed. : Generation of paper dust is slightly observed, but there is no practical problem. Δ: Generation of paper dust is clearly recognized. ×: A lot of paper powder is deposited on the blanket, and the blanket is white. [Contact angle] A newsprint sample was prepared to an appropriate size.
Cut into pieces, add 5 μl of water (20 ° C.) dropwise, and after 1 second
Tactile contact angle meter (dynamic absorption tester
-DAT1100 / FIBRO)
Was. [0039] [Table 1] [0040] As is clear from the results shown in Table 1, the present invention
The newsprint obtained in the example of Example 1 has excellent color print quality.
With blanket paper powder piling or blanket
Excellent offset printing newsprint without sticking
Was.

Continuation of front page (56) References JP-A-8-232193 (JP, A) JP-A-4-59805 (JP, A) JP-A-11-107190 (JP, A) JP-A-9-13298 (JP, A) , A) JP-A-1-221597 (JP, A) JP-A-8-282095 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D21H 11/00-27/42 C09D 101/00-201/10

Claims (1)

(57) [Claims 1] In a newsprint for offset printing obtained by applying and drying a surface treatment agent on base paper, the surface treatment agent
Is a water solution containing 40 to 80% by weight of a styrene monomer.
Based system containing a surface sizing agent and starch, which are water-soluble polymers
Product, and the amount of surface sizing agent applied is
Wherein the contact angle between the newsprint and the water (a value one second after a water droplet has dropped onto the paper surface) is 90 ° or more , wherein the contact angle is 0.03 to 0.1 g / m ^2. Newsprint paper for printing.