JP2003293290A - Newsprint paper for offset printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide newsprint paper for offset printing which has high opacity, has excellent color printing quality, and has excellent printing operability without blanket piling or blanket sticking. SOLUTION: Offset printing newsprint obtained by applying a surface treatment agent consisting of a pigment containing at least one of huntite and hydromagnesite and an adhesive onto a base paper and drying the base paper has high opacity and is excellent. Printing operability and color printing quality.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an offset printing newsprint having excellent printing workability and excellent color printing quality.

[0002]

2. Description of the Related Art In recent years, newspaper printing has rapidly progressed in offsetting, colorization, and speeding up, and there is a demand for a paper having better color printing suitability and printing workability as a printing medium. Has been.

By the way, in offset printing, since a printing ink having a relatively high tack is used, it is required that the surface of the paper has a high strength. Further, since dampening water is used, surface water resistance is required. Paper with weak surface strength,
Alternatively, when a paper having a surface with low or no water resistance is used, paper dust is accumulated on the blanket or mixed in the ink, which causes a problem of so-called scraping on the printing surface. For this reason, conventionally, newsprint paper for offset printing is generally coated with starch, polyvinyl alcohol (hereinafter abbreviated as PVA), polyacrylamide, or the like on its surface.

[0004]

Each of these external additive coating agents is effective in suppressing the generation of paper powder, but has poor water resistance and is liable to cause blanket piling and nepparing troubles. In addition, the use of a large amount of these surface treatment agents suppresses the penetration of the ink into the paper surface, so uneven ink absorption (color unevenness on the printing surface) is likely to occur due to coating unevenness during color printing. There are difficulties.

Further, with the recent weight reduction of newsprint paper, high opacity after printing is required for the paper. In order to increase the opacity of paper, hydrated silicic acid, titanium oxide, inorganic pigments such as talc, and organic pigments such as urea-formaldehyde resin have been widely used as papermaking fillers. Of these, hydrated silicic acids, commonly called white carbon, are most widely used because of their low cost and opacity improving effects. The hydrated silicic acids generally have a very small primary particle size and are relatively uniform, but in most cases form secondary aggregates, and the particle size at the time of use ranges from small particle size to large particle size. It is widely distributed up to the diameter, and when such fillers are added to papermaking pulp to make paper, the particles in the small particle size region, which is effective in improving opacity, does not stay well on the paper and is a sufficient effect. In order to obtain, it is necessary to increase the addition rate.

However, these fillers tend to be easily leached from the inside of the paper layer by the dampening water used in the printing process at the time of offset printing when the addition ratio is increased,
It is one of the main ingredients of the paper dust that is piled on the blanket. In addition, DIP, which is regarded as important in terms of environment
(Deinked waste paper pulp) is highly compounded by DIP in GP and R
The opacity is lower than that of mechanical pulp such as GP and TMP, and it is actually extremely difficult to achieve both improvement of opacity and high-dip blending of DIP.

[0007] In order to deal with such a drawback of the newsprint paper for offset printing, conventionally, starch or P is added to the surface of the newsprint paper.
It is generally practiced to apply a surface treatment agent containing VA, polyacrylamide or the like as a component. Although these surface treatment agents have the function of improving the paper surface strength and adhering the fine fibers and fillers on the paper surface to pulp fibers and the like,
It increases the tackiness on the surface of newsprint (hereinafter referred to as "Neppari"), resulting in sticking to a blanket during printing, wrinkles, and running problems such as paper breaks.

In combination with ordinary pigments such as kaolin and calcium carbonate used in the field of general coated paper, PVA is used.
Although it is possible to reduce the nepparability of surface treating agents such as the above, it was insufficient for producing a newsprint having high opacity, which is the object of the present invention. On the other hand, titanium dioxide, which is known as a pigment with high opacity, can obtain good opacity as compared with the case of using other pigments, and an improvement effect on the nepparability is recognized, but The compatibility was poor, and agglomerates were likely to occur during coating, making stable operation difficult. Further, there is a problem that the blanket is white and dirty during offset printing, and it is difficult to wipe it. On the other hand, hydrated silicic acids such as white carbon and amorphous silica have a high oil absorption, so by applying these, good opacity after printing can be obtained, but since the surface strength is weak, There is a problem that paper dust piles up during printing.

Due to the above-mentioned circumstances, various methods have conventionally been proposed for offset printing newsprint in order to obtain high opacity and good surface strength. For example, a method of increasing the opacity by providing a coating layer containing a filler having an oil absorption of 65 to 150 cc / 100 g on the surface of the base paper (JP-A-1-17497), a pigment and a specific latex (SBR), / Or a method of applying a composition containing a water-soluble adhesive as a main component in an amount of 0.3 to 3 g / m ² (JP-A-2-19595), a binder containing starch and latex, and a specific amount of a plastic pigment or There has been proposed a method of providing a coating layer containing a specific amount of an organic pigment such as a binder pigment (JP-A-5-263394).

However, in the case of a base paper having a low rice slab weight of 45 g / m ² or less and a waste paper pulp content of 40% by weight or more, the amount of rice slab (coating (Working amount) is kept constant by lowering the tsubo of the base paper made of pulp fiber, the opacity that decreases due to this pulp fiber reduction cannot be completely covered by ordinary pigment coating, and it is also suitable for color printing. Moreover, no results have been found that can satisfy the elimination (reduction) of blanket piling.

The present inventors have conducted extensive studies as a newsprint for offset printing to obtain a lightweight newsprint having both a high percentage of waste paper and excellent suitability for offset printing. An object of the present invention is to provide an offset printing newsprint having high opacity, excellent color printing quality, and excellent printing operability without blanket piling or blanket sticking.

[0012]

The present invention provides an offset printing newsprint obtained by applying a surface treatment agent comprising a pigment and an adhesive onto a base paper and drying the pigment, wherein the pigment is at least huntite and hydromagnesite. The present invention relates to an offset printing newsprint characterized by containing one kind.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The pigment containing at least one of huntite and hydromagnesite used in the present invention is applied to a paper by using it in combination with an adhesive such as starch, polyacrylamide or polyvinyl alcohol. It was observed that the opacity was increased and a printed surface with good ink receptivity was provided. Further, it has a feature that problems such as blanket piling due to paper dust and sticking of blanket due to Nappari, which deteriorate the printing workability, can be solved.

The amount of at least one of huntite and hydromagnesite used in the present invention is 50 to 100 parts by weight, preferably 80 to 100 parts by weight, based on 100 parts by weight of the total pigment solid content. Such a high proportion of huntite and / or hydromagnesite is
It becomes possible by adjusting the solid concentration of the surface treatment agent to a low concentration of 20% by weight or less. When the addition amount of at least one of huntite and hydromagnesite is less than 50 parts by weight, the effect of improving opacity and ink receptivity is insufficient.

In the present invention, huntite is a thin-film plate-like mineral represented by Mg ₃ Ca (CO ₃ ) ₄ in mineralogy compositional formula, and hydromagnesite (Hydro).
Magnesite) the composition formula _{Mg 4 (OH) 2 (CO} 3) 3 · 3H
₂ O) is a thin film plate-like mineral. These huntites and hydromagnesites are naturally produced as a mixture of these, and are usually magnesites (Magnesite, M).
gCO _3), including calcite (Calcite, CaCO _3), aragonite (Aragonite, the impurities of CaCO ₃₎ and the like. Then, after crushing the rough stones, the ones classified by elutriation or elutriation are commercially available. Here, the average particle size of huntite and hydromagnesite is not particularly limited, and from the viewpoint of surface strength, smoothness, etc., the average particle size is about 0.2 to 1 μm, particularly 0.3 to 0.1. It is preferably about 6 μm. Here, the average particle diameter was measured with a sedigraph 5100 (manufactured by Micromeritics).

The reason why the pigment containing at least one of huntite and hydromagnesite is excellent in ink receptivity, opacity and ink setting, and effective in nepparing resistance and blanket piling is presumed as follows. It That is, since huntite and hydromagnesite are tabular particles, when a surface treatment agent containing at least one of huntite and hydromagnesite is applied to the paper surface, a card house structure is formed by the interaction between particles, Since the particles are oriented parallel to the surface of the paper and have excellent smoothness, the ink receptivity is improved, and on the other hand, the hiding property is increased and the opacity is improved. In addition, since the adhesion between the paper and the blanket is alleviated by the pigment particles,
Nepperiness caused by the tackiness of the binder component is also reduced.

Examples of the adhesive used in combination with the pigment containing at least one of huntite and hydromagnesite include starches such as enzyme-modified starch, oxidized starch, cationized starch and phosphoric acid esterified starch, and carboxymethyl cellulose. , Water-soluble cellulose compounds such as methyl cellulose and hydroxyalkyl cellulose, completely or partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, polyvinyl alcohol such as silicon modified polyvinyl alcohol, polyacrylamides, styrene-butadiene copolymer, methyl methacrylate -Synthetic latexes such as butadiene copolymers. Of these adhesives, starches and polyacrylamides are particularly preferable because they have good compatibility with the pigment.

Further, as the surface treatment agent, in addition to a pigment and an adhesive containing at least one of the above-mentioned huntite and hydromagnesite, a surface sizing agent and an antifoaming agent which are usually used in the field of papermaking and coated paper. , An antiseptic, a thickener, etc. are appropriately used in combination.

Further, pigments for coated paper used in the field of producing general coated paper, for example, kaolin, clay, calcined kaolin, amorphous silica, zinc oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, titanium dioxide. Inorganic pigments such as aluminum silicate, magnesium silicate, magnesium carbonate, and satin white, and plastic pigments can be appropriately mixed and used, but pigments containing at least one of huntite and hydromagnesite. Is 50% by weight or more of the total pigment,
It is preferably 80% by weight or more to improve opacity and ink receptivity.

The proportion of at least one of huntite and hydromagnesite is preferably 50 to 300 parts by weight in terms of solid content relative to 100 parts by weight of the total adhesive in the surface treatment agent. By the way, if it is less than 50 parts by weight, the effect of improving the nepparability and opacity is not sufficient, and if it exceeds 300 parts by weight, the piling of paper dust may be deteriorated.

The surface-treating agent thus obtained is adjusted to a solid content concentration of 1 to 20% by weight and coated on newsprint base paper. The coating amount is usually 0.05 dry weight per side.
-4 g / m < ² >, preferably 0.1-3 g / m < ² > on both sides of the base paper. By the way, the coating amount is 0.05g
If it is less than / m ² , it is difficult to obtain sufficient surface strength,
On the other hand, when it exceeds 4 g / m ² , the nepparability is increased, and sticking to a blanket is a concern.

The newsprint base paper according to the present invention includes:
Chemical pulp (NBKP, LBKP) as raw material pulp
Etc.), mechanical pulp (GP, CGP, RGP, PGW, T
MP, etc.), waste paper pulp (DIP, etc.), etc. are used alone or mixed at an arbitrary ratio. Further, a filler such as white carbon, clay, amorphous silica, talc, titanium oxide, calcium carbonate, and satin white is added to the paper stock to make a paper. In addition, sizing agents such as paper strength enhancers, yield improvers, reinforced rosin sizing agents, emulsion sizing agents,
Generally known publicly known papermaking chemicals such as a water resistant agent and an ultraviolet absorber are added, and papermaking is carried out by a publicly known papermaking machine. The basis weight of the base paper is not particularly limited, but the effect of improving opacity is particularly remarkable when used for a thin material of 30 to 42 g / m ² .

The surface treatment agent, which is a feature of the present invention, is applied and dried on the above-mentioned newsprint base paper, but the application device in that case is not particularly limited, and for example, 2
A roll size press, a blade metalling size press, a rod metalling size press, a gate roll coater, a blade coater, a bar coater, a rod blade coater, an air knife coater, a curtain coater, a spray coater and the like are appropriately used.

The newsprint thus obtained is passed through a calendar, if necessary, and subjected to pressure and smoothing treatment to be finished into a product. The calendering device in that case is not particularly limited, and a soft calender, a hard nip calender, a super calender, or the like is appropriately used.

[0025]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Unless otherwise specified, parts and% in the examples indicate parts by weight and% by weight, respectively, and parts by weight indicate parts by weight in terms of solid content.

Example 1 (papermaking of newsprint base paper) Softwood kraft pulp (NB
KP) 10 parts, thermomechanical pulp (TMP) 30
Part, ground pulp (GP) 20 parts, deinked waste paper pulp (DIP) 40 parts were mixed and disintegrated, and white carbon having an average particle diameter of 23 μm was added to pulp prepared with a refiner to 100 ml of Canadian standard freeness (CSF). As a filler, 1% was added per dry dry pulp, and papermaking was performed by a gap former type paper machine to obtain a newsprint base paper having a weight of 40 g / m ² .

(Applying surface treatment agent) As an adhesive, 100 parts by weight of starch (trade name: Ace A / Oji Corn Starch) dissolved in hot water as a solid content and an average particle size containing 90% or more of huntite as a pigment are used. Is 0.4 μm natural mineral (trade name: Neracarb HH / Incemin AG
Company) 100 parts are mixed and diluted with water to obtain a solid concentration of 1
0% of surface treatment agent was obtained. Using this surface treatment agent on both sides of the newsprint base paper using a gate roll coater,
1.1g / m ² coating per side, after drying, linear pressure 13
Calendar paper was passed under the condition of 0 kg / cm to obtain newsprint for offset printing.

Example 2 In Example 1, the pigment contained about 50% Huntite and about 50% hydromagnesite and had an average particle size of 0.6 μm.
Natural minerals (trade name: Neracarb FF / Incemin
A newsprint for offset printing was obtained in the same manner as in Example 1 except that the amount was 100 parts. The coating amount at this time was 1.0 g / m ² per side.

Example 3 In Example 1, a natural mineral containing 90% or more of huntite and having an average particle size of 0.4 μm (trade name: Neracarb HH)
For the offset printing in the same manner as in Example 1 except that the addition amount of the above is 60 parts, the solid concentration of the surface treatment agent is 12%, and the coating amount is 1.1 g / m ² per side. I got a newspaper.

Example 4 In Example 1, as an adhesive, polyacrylamide (trade name: NP10 / Mitsui Chemicals, Inc.) 10 was used instead of starch.
A newsprint for offset printing was obtained in the same manner as in Example 1 except that 0 part was used. The coating amount at this time is 0.
It was 8 g / m ² .

Comparative Example 1 Example 1 was repeated except that no pigment was added.
A newsprint for offset printing was obtained in the same manner as described above. The coating amount at this time was 0.5 g / m ² per side.

The quality of the newsprint for offset printing obtained in these Examples and Comparative Examples was evaluated by the following method, and the results are shown in Table 1. "Blanket paper dust piling" Offset rotary press (Mitsubishi Lithopia L-BT 3-1100 / Mitsubishi Heavy Industries, Ltd.) is used to perform continuous four-color 5000-color color printing, and the degree of paper dust accumulation on the blanket non-image area. Was visually determined. <Judgment Criteria> ◯: Generation of paper dust is not recognized. Δ: Occurrence of paper dust is recognized to such an extent that it poses a practical problem. X: A lot of paper dust is accumulated on the blanket.

"Ink receptivity" The ink receptivity by the above printing was visually determined. <Judgment Criteria> O: Good inking property. Δ: Poor inking is recognized to such an extent that it poses a practical problem. X: Many defective inking are recognized.

"Nappari strength (blanket adhesion)"
Two sheets of newsprint paper for offset printing were cut into an appropriate size, dipped in water for 10 seconds, then quickly brought into close contact with each other, and passed through a calender at a linear pressure of 100 kg / cm, and 24
After being dried at room temperature for an hour, the peel strength of the two sheets of paper was measured using a tensile tester. The larger the number, the stronger the tackiness.

[0035]

[Table 1]

[0036]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain a newsprint for offset printing which has a high opacity, an excellent color printing quality, and is free from blanket piling and blanket sticking and has excellent printing operability.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuhiro Nojima             Prince, 3-3-1, Jokoji Temple, Amagasaki City, Hyogo Prefecture             Amagasaki Research Center, Paper Manufacturing Co., Ltd. F-term (reference) 4L055 AA02 AC02 AC03 AC06 AC09                       AG25 AG47 AG72 AH02 AH37                       AJ04 BE08 BE20 EA14 EA32                       FA15 GA16 GA19

Claims (3)

[Claims] 1. A newsprint for offset printing, which is obtained by applying a surface treatment agent comprising a pigment and an adhesive on a base paper and drying the pigment, wherein the pigment contains at least one of huntite and hydromagnesite. Newsprint for offset printing. 2. The offset printing according to claim 1, wherein at least one of huntite and hydromagnesite is used in a proportion of 50 to 300 parts by weight based on 100 parts by weight of the total adhesive in the surface treatment agent. Newsprint. 3. The content of at least one of huntite and hydromagnesite is 50% by weight or more with respect to the total pigment, and the coating amount of the surface treatment agent is 0.1 on each side.
The newsprint paper for offset printing according to claim 1 or 2, which has a weight of about 3.0 g / m ² .