JPH0598593A - Bulky medium paper for offset printing - Google Patents

Abstract

PURPOSE:To provide the subject mechanical paper having a prescribed bulk density and a strong nerve, excellent in the surface strength, ink setability, printability, smoothness and workability and suitable for magazines, etc. CONSTITUTION:Both the surfaces of a paper support containing mechanical pulp (e.g. pressed stone-ground pulp) in an amount of 65-95wt.% based on all pulps, 20-80wt.% of the mechanical pulp being constituted of thermo-mechanical pine pulp, are coated with a clear sizing coating comprising starch oxide in a rate of 0.5-1.5g/m<2>. preferably 0.8-1.2g/m<2>, to provide the objective mechanical paper having a bulk density of 0.40-0.55g/cm<3>.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium-quality paper for offset printing, and more specifically, it is a paper having ink receptivity and surface strength characteristics required for offset printing, and has a uniform thickness even at a constant basis weight. The present invention relates to a medium-quality paper for offset printing having a thick and bulky characteristic.

[0002]

2. Description of the Related Art In recent years, in the publishing industry, there is a strong tendency to visualize and color printed matter, and as a printing method, offset printing that can obtain a good printing surface even if the surface smoothness of the paper is relatively low Is growing, and this tendency has spread to publications such as comic magazines, boys 'and girls' magazines,
In addition, since magazines and books with a large thickness are preferred for the number of pages, the paper is required to have a certain thickness at a constant rice basis weight, that is, be bulky and have strong properties.

As this bulky paper, in the past, esparto grass (esparto, Spanishgrass), dragon su grass (Ronsuso).
Alternatively, paper made from pulp made from rag (Rag) was said to be suitable for this purpose (published September 20, 1989, Pulp and Paper Encyclopedia, pages 53 and 153; Paper and Pulp Technology). Journal No. 21, No. 10 (October 1967 issue)
41-52).

However, the above-mentioned pulp from herbaceous plants and pulp made from boro as raw materials do not meet the demand in the current mass production era, and are generally used due to restrictions on raw material supply. In addition to the problem that the paper is difficult to produce, the paper produced from these raw materials is inferior in paper strength, particularly surface strength, and thus is not suitable for offset printing.

In offset printing, when the surface strength of the printing paper is weak, the pulp fibers existing on or near the surface of the paper are pulled out (picking) from the paper surface due to the high tackiness of the printing ink during printing. Adhesion to a blanket or a printing plate that comes into contact with the paper impairs the quality of the printing surface, or causes so-called paper dust troubles that accumulate on various rollers of a printing machine. Further, if the tensile strength of the printing paper is weak, a paper break or the like may occur at the time of pasting (pasting) in which the rolled paper is continuously glued to the next rolled paper. As a result, a situation will occur in which the modern printing methods such as offset printing and continuous high-speed printing cannot be fully supported.

[0006] As a bulky medium-quality paper currently on the market, Machine Finis manufactured by Tampera of Finland.
hed Bulky paper tom creamy (registered trademark;
43-0.45) is well known, but although this paper is excellent in opacity and print-through (strikethrough), it has problems in ink receptivity and surface strength. .. There is a demand for the development of bulky medium-quality paper that does not cause paper dust troubles in offset printing and is satisfactory in both print workability and print quality.

As described in Japanese Patent Publication No. 55-47385, as a method for producing paper that is bulky on the machine side in the paper making process, the vacuum degree of the suction roll of the press part and the lower part dryer cylinder and the upper part of the dry part are described. It is known to produce paper with a tighter paper by adjusting the surface temperature difference of the dryer cylinder as well as the calender nip number or nip pressure. In some cases, a method in which no calendering is carried out is exemplified, but in this case, the smoothness of the surface of the paper is deteriorated, while the quality of the printed matter typified by ink receptivity is also deteriorated. is there.

On the other hand, for the purpose of improving the ink receptivity during printing, it is considered effective to strengthen the beating treatment of the chemical pulp and / or the mechanical pulp to lower the freeness of the pulp. Ink quality improves, but
It is not applicable for the purpose of producing bulky papers because of the high paper tightness.

Therefore, in order to produce a thick paper while keeping the ink inking during printing and the surface strength of the paper well, paying attention to the pulp itself, the ink inking property is good,
In addition, it is necessary to use mechanical pulp having a high surface strength to reduce or omit the calendering process.

For the purpose of producing bulky medium-quality paper, pine (pine), spruce, which is a softwood material,
Pressurized stone ground pulp (PGW), thermomechanical pulp (TMP), which is made from fir, etc.
Mechanical pulp such as stone ground pulp (GP) and refiner ground pulp (RGP) is suitable. And regarding the recent production technology of these mechanical pulps, for example, Paper and Paper Cooperative Magazine Vol. 40 No. 7 (July 1986), pp. 9-19, Vol. 41 No. 10 (October 1987). No. 14 to 25, Paper Pulp Technology Times Vol. 33, No. 4 (March 1980), pages 38 to 50.

These mechanical pulps include chemical pulps such as sulfite pulp (SP), kraft pulp (KP) and polysulfite pulp, and chemi-mechanical pulps such as chemi-thermo-mechanical pulp (CTMP) and chemi-ground pulp (CGP). The pine wood silicon TMP has a lower rigidity than that of the above, and the fiber is generally rigid and has a property of not easily crushing. Therefore, it is suitable as a target raw material pulp for bulky medium-quality paper. It is possible that

In general, however, the mechanical pulp varies depending on the type of pulp and the degree of beating, but the surface strength of the paper is weak, and the printing workability due to defective printing surface due to paper sticking during printing or paper dust accumulation. Is likely to occur.

On the other hand, as a means for improving the surface strength of paper, there is a method of impregnating or applying an adhesive such as starch or polyvinyl alcohol on the surface of paper by a size press or the like.

However, in general, impregnation and application of an adhesive such as starch or polyvinyl alcohol increases the tightness of the paper, and a paper of a thin paper thickness can be obtained at a constant basis weight of the paper, which is eventually bulky. It will be different from the direction in which the paper is obtained.

As described above, in the present pulp raw materials and technologies, the paper thickness is thick with a constant basis weight, that is, bulky, and the printability (in particular, the ink receptivity and the improvement of the surface strength due to the application of an adhesive) are required. It has different and antinomy elements,
At present, a satisfactory bulky medium for offset printing has not been obtained.

[0016]

An object of the present invention is to provide a clear size coating layer on a paper support without providing a coating layer containing a pigment on the paper support, and a mechanical pulp is used as the paper support. To provide bulky medium-quality paper for offset printing, which is excellent in opacity, print-through (ink-through), ink inking property, and does not cause paper dust troubles in offset printing by using the medium-quality paper as the main component. Exist.

In view of the above-mentioned problems, the present inventors have made multi-faceted examinations on the blending amount of mechanical pulp, the type of mechanical pulp, the species of softwood, the blending amount of filler, and the coating amount of clear size in medium-quality paper. The present invention has been completed by knowing that it is possible to obtain a medium quality paper for offset printing which is a bulky medium quality paper, which has good ink receptivity and has a high surface strength.

[0018]

According to the present invention, 65 to 95% by weight of all pulp components is mechanical pulp, and 20 to 80% by weight of mechanical pulp components is composed of pine thermomechanical pulp. A bulky offset characterized in that a clear size coating is applied on both sides of 0.5 to 1.5 g / m ² on a paper support having a tenacity of 0.40 to 0.50 g / cm ^3. It is a medium quality paper for printing.

The mechanical pulp usable as the base paper for clear size coating (paper support) used in the present invention includes pressurized stone ground pulp (PGW), thermomechanical pulp (TMP) and stone ground pulp (G).
P), refiner ground pulp (RGP), and the like.
Must be contained by weight, preferably 70% to 90%
Is. And it is necessary to contain 20 to 80% by weight, preferably 30 to 70% by weight, of pine-based thermomechanical pulp (TMP) in the mechanical pulp component.
The remaining 25 to 5% by weight is soda pulp (AP),
It is composed of chemical pulp such as sulfite (SP) and kraft pulp (KP), and these are blended as bleached pulp and semi-bleached pulp. Further, chemi-mechanical pulp such as chemi-thermo-mechanical pulp (CTMP) and so-called high-yield pulp such as semi-chemical pulp (SCP) are appropriately blended.

Further, unbleached, semi-bleached and bleached high-yield pulps widely used for newsprint, paperboard, medium-quality paper, medium-quality coated paper, waste paper, etc. are slush pulp, wet pulp, and dry pulp. The recycled waste paper containing these high-yield pulps and the waste paper for deinking recovery are mixed and used.

Further, the above-mentioned PGW, TMP, GP,
DIP deinked from waste printing paper such as newsprint waste paper, medium-quality paper, medium-quality coated paper containing one or more types of mechanical pulp such as RGP
Can also be compounded.

In the present invention, mechanical pulp is blended in an amount of 65 to 95% by weight based on the total pulp components, and 20 to 80% by weight in the mechanical pulp components needs to be thermomechanical pulp (TMP). And as the species, softwood pine (Pine), spruce (Spruce), and fur (Fir) can be used, but preferably pine (Pine)
, Jack Pine (P. banksiana), Lodgepole Pine
(P. contorta), Slash Pine (P. elliottii), Mont
erey Pine (P. radiata) 、 Ponderosa Pine (P. pondero
sa), Loblolly Pine (P. taeda), etc., more preferably so-called radiata pine, which is widely planted in Australia and New Zealand,
It is a TMP obtained from Ponderosa pine.

The fiber shape of these pine wood-based TMPs is good in defibration because the wood chips softened by press teaming are subjected to pressure refining as they are, and the cutting and binding fibers of the fibers are small, It has a good long fiber shape. For this reason, paper containing TMP generally has low density, becomes bulky, and has improved oil absorption, so that ink receptivity is also improved.

The degree of beating of TMP used in the present invention is important, and it is necessary to use the beating of 100 ml CSF (Canadian standard freeness) or less at the freeness specified in JIS P8121. , Preferably 80 to 100 ml CSF, more preferably 90 to 95
The desired quality can be obtained by using beating in the range of ml CSF.

Generally, if the pulp has a high freeness, the surface of the paper becomes rough, the surface smoothness of the paper is deteriorated, and ink inking is deteriorated. If you attach importance to the ink receptivity, which is the quality of the printed surface of the paper, the lower the freeness, the better the surface smoothness,
Although preferable, if the freeness is lowered too much,
The tightness of the paper becomes high and the paper does not become bulky.

In general, the higher the blending ratio of mechanical pulp, the better the ink receptivity, which is the quality of the printed surface,
On the other hand, the paper strength represented by tensile strength, tear strength and burst strength is usually reduced. However, TMP using pine wood as the material type is not suitable for other mechanical pulps (PGW, RGP,
The tensile strength and tear strength are stronger than those of GP).
In the present invention, bulky paper having sufficient paper strength can be obtained by incorporating 20% by weight to 80% by weight of the mechanical pulp component in the present invention.

If necessary, an inorganic filler is added to the above-mentioned mechanical pulp, chemical pulp, etc. as an auxiliary material. Examples thereof include talc, clay, titanium oxide, white carbon and calcium carbonate. The addition amount of these is added to the pulp slurry so as to be 10 to 20% by weight based on the dry weight of the paper after paper making. By adding the inorganic filler, a bulky paper having both rigidity and flexibility can be obtained, but the bulkiness is lost when the inorganic filler is mixed in a large amount.

In addition to inorganic fillers, sulfuric acid bands, sizing agents, paper strength enhancers, retention aids, pigments, colorants, fluorescent dyes, defoamers, and other papermaking materials may be included in the papermaking raw material, if necessary. Chemicals are added and paper is made as acidic paper or neutral paper.

In the present invention, the pulp slurry comprising the above pulp, filler and paper-making chemicals is used in a general paper machine to have a basis weight of 60 g / m ^{2 to} 76 g / m ² and a thickness of 130 mμ.
A medium-quality paper of about 170 mμ is made.

[0030] The present invention 0.5 to 1.5 g / m ² more clear size coating weight on the paper support on both sides in, is preferably applied 0.8g / m ² ~1.2g / m ² .. By providing this clear size coating layer on the support,
Workability at the time of printing is also improved by preventing clearing of the paper at the time of offset printing and at the same time increasing the stiffness (stiffness) of the paper by applying clear size paint.

[0031] There are cases where the surface strength when the coating amount is less than 0.5 g / m ² is not fully satisfactory, 1.5 g / m ²
When it exceeds the range, it is preferable for improving the surface strength, but there are problems that the same basis weight increases the tightness, impairs the degree of bulkiness, and leads to an increase in manufacturing cost.

The paint components used in the clear size coating layer used in the present invention include alkali-sensitive synthetic resin emulsions, alkali-insensitive synthetic resin emulsions, oxidized starch, esterified starch, enzyme-modified starch,
Examples thereof include modified starches such as cationized starch, proteins such as casein and soybean protein, fibrin derivatives such as carboxyethyl cellulose and hydroxyethyl cellulose, and water-soluble synthetic resins such as polyvinyl alcohol.

Further, it is of course possible to appropriately add various auxiliaries such as a dispersant, a flow modifier, an antifoaming agent, a dye, a lubricant, a water-proofing agent, and a cross-linking agent to the clear size coating solution, if necessary. ..

In the present invention, the coating method of the clear size coating solution is not particularly limited, and a conventionally known two-roll size press, air knife coater,
A roll coater, a gate roll coater, or a blade coater is used to coat the blades on-machine or off-machine with various coating devices such as hebel and bent type coaters, and bill blades and twin blades.

The paper coated with the clear size paint in the present invention is not usually calendered, but may be surface-treated by a calender if necessary. In this case, the calender roll may be a metal roll alone, or a soft nip type roll such as a rubber roll.
Finally, the medium quality paper for offset printing of the present invention has a tightness of 0.40 to 0.50 g / cm ³ .

[0036]

EXAMPLES The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Parts and% in the examples and comparative examples are parts by weight and% by weight, unless otherwise specified.

The pulps used in Examples and Comparative Examples have the physical properties shown in Table 1 below.

[Table 1] * 1 Measured according to JIS P8121 * 2 Adjusted according to JIS P8209, JIS P8118
Measured using * 3 New Zealand radiator pine * 4 Using Hokkaido mixed spruce, Todomatsu and larch

Example 1 Radiator pine (New Zealand) material TMP20
Per 100 parts of dry pulp of a pulp composition consisting of 10 parts, 15 parts of GP, 55 parts of RGP and 10 parts of NBKP (mechanical pulp is 90% of the components, mechanical pulp is 22% of the components is pine-based TMP). Internal sizing agent (SPG,
Arakawa Chemical Co., Ltd.) 0.5 parts, sulfuric acid band 1.5 parts, talc 27 parts added 0.12% concentration pulp slurry using a paper machine capable of making medium or newsprint paper. A paper support having an amount of 61.0 g / m ² , a thickness of 132 mμ, and an ash content of 16% was produced.

On the other hand, steamed oxidized starch (Oji Ace A, manufactured by Oji Corn Starch) as a clear-size coating liquid and polyvinyl alcohol (PVA) in a weight ratio of 5
The mixture mixed at 0:50 was adjusted to 2.5% concentration, and the coating speed was 430 m using an on-machine 2 roll size press.
The coating amount was 0.50 g / m < ² > on each side in 1 / min, and after drying, a medium quality paper for offset printing was obtained (calendering not performed). The basis weight of this paper was 62 g / m ² , and the tenacity was 0.46 g / cm ³ , and the results relating to the surface strength and the ink receptivity when printing this paper are shown in Table 2.

Comparative Example 1 TMP of the pulp composition of Example 1 was RGP.
(Freeness 100 ml C.SF, severity 0.36). (In this case, the mechanical pulp does not change to 90% of the total pulp, but the TMP in the mechanical pulp becomes 0%.) Therefore, during offsetting under the same conditions as in Example 1 except that the RGP content was 75 parts. I got quality paper. The basis weight of this paper is 62 g /
The tenacity in m ² is 0.46 g / cm ³ , and the results relating to the surface strength and the ink receptivity when printing this paper are shown in Table 2.

Example 2 20 parts of TMP, 30 parts of RGP, 15 parts of GP, PGW25
Part, NBKP 10 parts, the pulp composition (mechanical pulp is 90% of the total pulp, 22% of the mechanical pulp is pine wood-based TMP). In the same manner, a medium quality paper for offset printing having a basis weight of 62 g / m ² was obtained. The tightness of this paper is 0.48, and the results regarding the surface strength and the ink receptivity when printing this paper are shown in Table 2.

Comparative Example 2 10 parts of TMP in the pulp composition constituted in Example 2 were replaced with RGP (the same as in Example 1) (in this case, mechanical pulp was unchanged at 90% of all pulp components). But,
The TMP in the mechanical pulp component is 11%. ). Therefore, a medium quality paper for offset printing was obtained under the same conditions as in Example 1 except that the RGP content was 40 parts. The basis weight of this paper is 62
The tenacity is 0.48 in g / m ² , and the results relating to the surface strength and the ink receptivity when printing this paper are shown in Table 2.

Example 3 Pulp composition consisting of 35 parts of TMP, 55 parts of RGP and 10 parts of NBKP (mechanical pulp is 90% in all pulp components and 39% in mechanical pulp component is pine-based TMP) and others. The same papermaking conditions as in Example 1 were used to obtain a medium quality paper for offset printing having a basis weight of 62 g / m ² . The tightness of this paper is 0.43, and the results regarding the surface strength and the ink receptivity when printing this paper are shown in Table 2.

COMPARATIVE EXAMPLE 3 In the pulp composition of Example 3, 25 parts of TMP was replaced with RGP. (In this case, the mechanical pulp does not change to 90% of the total pulp components, but the TMP in the mechanical pulp becomes 11%.) Therefore, the offset was performed under the same conditions as in Example 1 except that the RGP content was 80 parts. A medium quality for printing was obtained. The basis weight of this paper is 62 g / m ² and the tenacity is 0.43. The results relating to the surface strength and ink receptivity when printing this paper are shown in Table 2.

Comparative Example 4 In the pulp composition of Example 3, 25 parts of TMP were replaced with 25 parts of deinked waste paper pulp (in this case, mechanical pulp accounted for 65% of all pulp components, TMP is 15%.) Under the same conditions as in Example 1, a medium-quality paper for offset printing was obtained. The basis weight of this paper is 62 g / m
^The tenacity at ² was 0.52, and the results regarding the surface strength and the ink receptivity when printing this paper are shown in Table 2.

Comparative Example 5 Among the pulp compositions constituted in Example 3, TMP was replaced with one using Ezo pine, Todo pine and Japanese larch (produced in Hokkaido) (freeness 90 ml C.S.F. tightness 0.37). (In this case, the mechanical pulp is 90% of the total pulp component, and 35% of the mechanical pulp component is pine wood-based TMP.
Becomes Other conditions were the same as in Example 1 to obtain a medium-quality paper for offset printing. The basis weight of this paper is 62 g / m ² and the tenacity is 0.45. The results relating to the surface strength and the ink receptivity when printing this paper are shown in Table 2.

The test methods and evaluation methods relating to the surface strength shown in Table 2 are as follows. (Diamond surface strength) 2-color offset sheet-fed printing machine DA
Using IYA IE-2 type (manufactured by Mitsubishi Heavy Industries, Ltd.),
The nip pressure of the blanket was adjusted to be constant, printing was performed under the following conditions, and the number of stripped sheets in the heavy color portions of the front surface (F) and the back surface (W) was counted and evaluated by a 5-step method. The higher the score, the better. ○ Printing conditions Ink type Offset ink Ink tack 9 Printing speed 7,000 sheets / hour ○ Five-step evaluation standard 5 points 0-23 pieces / m ² 4 points 24-47 〃 3 points 48-72 〃 2 points 73-95 〃 1 Point 96-〃

(RI surface strength) RI printability tester R
I-2 type (manufactured by Akira Seisakusho Co., Ltd.), when printed under the following conditions, the fluffing of fibers on each surface of the front surface (F) and the back surface (W) and the peeling state of the fibers are visually observed. It judged and evaluated by the 5-step method. The higher the score, the better. The average value of three determinations was displayed. ○ Printing conditions Ink type Polybden ink Ink tack 22 Blanket nip pressure 10mm Printing speed 30rpm ○ Five-step evaluation standard 5 points Very good without fluffing or peeling of fibers 4 points 1 to 5 pieces of fiber peeling No. 3 points There are 6 or more pieces of fiber peeling, but there is no occurrence on the entire surface. 2 points There is partial scattering of fiber peeling. 1 point Is there any peeling of fibers on the whole surface? Or each peeling is large

(Ink receptivity) Two-color offset sheet-fed printing machine DAIYA 1E-2 type (manufactured by Mitsubishi Heavy Industries, Ltd.)
And print under the following conditions, and the front (F) and back (W)
The printed surface of was compared with a limit sample and sensory-evaluated by a 5-step method.
The higher the score, the better. ○ Water loss Except that the amount of dampening water was increased, printing was performed under the same conditions as when measuring the diamond surface strength, and the state of white spots in the second color halftone dot area was visually evaluated and compared with a limit sample with a magnifying glass.

From the results shown in Table 2, those containing 20% or more of pine-based TMP (Examples 1, 2 and 3) had the same degree of strength (Comparative Example 1 and Example to Example 1). It can be seen that the surface strength and the ink receptivity are better than those of Comparative Example 2 for No. 2 and Comparative Example 3 for Example 3. Further, it can be seen that the one in which TMP is blended at 20% or less and the surface strength is improved by another pulp (Comparative Example 4) has a tightness of 0.52 and does not attain the target bulkiness. Further, it is understood that the same pine wood system, in which TMP obtained from a pine wood other than New Zealand radiator pine is blended (Comparative Example 5 with respect to Example 3), the tenacity is slightly higher and the surface strength is slightly weaker. Therefore, in order to be bulky, a large amount of mechanical pulp may be blended, but in order to improve the surface strength and to improve ink inking, a pine wood-based material, preferably a radiator pine ponderosa pine or other Nanyo pine wood is used. It can be seen that the formulation of TMP in the system is important.

[0051]

[Table 2]

[0052]

INDUSTRIAL APPLICABILITY The medium-quality printing paper for offset printing of the present invention has no calendar treatment after a clear-size coating layer is provided on paper containing pine thermomechanical pulp having a certain degree of freeness and tenacity. Or, by reducing the amount, the surface strength was strong, the stiffness was strong, and the ink receptivity and the workability during offset printing were excellent even though they were more bulky than the conventional bulky products.

Claims (1)

[Claims] 1. 65 to 95% by weight of all pulp components is mechanical pulp, and 20 to 80% of mechanical pulp components.
A clear size paint on both sides of the paper support composed of thermo-mechanical pulp whose weight% is pine wood
1.5 g / m ^{2 is} applied, and the tightness is 0.40 to 0.
Bulky medium-quality paper for offset printing characterized by having a weight of 50 g / cm ³ .