JP2002004196A - Special printing paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a white special printing paper having random reflection of light, soft visibility and giving a feeling of brightness from the inside of the paper, having so-called refined whiteness and whiteness with bottom gloss and excellent pliability or printability. SOLUTION: This special printing paper is characterized in that the printing paper has >=50 m2/kg specific scattering coefficient and <=1.4 contrast glossiness which is a ratio Φ/D of the positive reflected light component Φ to the diffused reflected light component D when measured at 60 deg. incident angle of light in a paper having >=85% whiteness and 2-60 s Bekk smoothness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to paper classified as special printing paper, and uses a conventional printing method such as offset printing or gravure printing, or a new printing method such as electrophotographic printing or ink jet printing. Poster,
The present invention relates to a special printing paper suitable for printing commercial art printing of catalogs, pamphlets, etc., book facing, book covers such as covers, texts, and packages.

[0002]

2. Description of the Related Art In the classification of paper, paper classified as special printing paper in printing and information paper includes high quality paper and other special printing paper, and other special printing paper includes commercial art printing. So-called fancy paper used for printing, publication printing, and the like. In conventional fancy paper, whiteness is felt such as yellowish or bluish, or cold whiteness due to fluorescent dyes even if the whiteness is high, And none of them had soft whiteness in sight.

[0003]

SUMMARY OF THE INVENTION The present invention is directed to a so-called "good whiteness" in which white special printing paper has a random reflection of light, is soft in visual sensation, and feels bright from the inside of the paper. , A paper having a "white with a glossy bottom". In the present invention, in addition to the whiteness, the specific scattering coefficient, and the smoothness, the ratio Φ between the regular reflection light component Φ and the diffuse reflection light component D when measured at an incident angle of 60 ° is used as an index of such characteristics. / D, and aims to provide a special printing paper having a soft product and whiteness with a desired visual feeling by manufacturing paper with these indices specified. Things.

Furthermore, the present invention provides excellent flexibility such as flexibility when used in the text of a book and ease of opening a page, and high opacity to the extent that printing is not transmitted to the back side, and excellent printability. This was done in consideration of the fact that it was paper.

[0005]

According to the present invention, a whiteness degree of 85 is provided.
% Or more, a paper having a Beck smoothness of 2 to 60 seconds, a specific scattering coefficient of 50 m ² / kg or more, and an incident angle of light of 6
The present invention relates to a special printing paper characterized in that the relative glossiness, which is the ratio Φ / D of the regular reflection light component Φ and the diffuse reflection light component D when measured at 0 °, is 1.4 or less.

The present invention also relates to a paper made by adding a white filler having a whiteness of 90% or more to bleached chemical pulp having a whiteness of 80% or more and adjusting the Beck smoothness to 2 to 60 seconds. Degree is 85% or more, and specific scattering coefficient is 50 m ^2.
/ Kg or more, and the relative glossiness which is the ratio Φ / D of the regular reflection light component Φ and the diffuse reflection light component D when measured at a light incident angle of 60 ° is 1.4 or less. Related to special printing paper.

[0007] The special printing paper according to the present invention is required to have a whiteness of 85% or more, preferably 90% or more. However, the upper limit of the whiteness that can be produced is 96 to 9
It is about 7%. The whiteness of paper is determined by the type of raw pulp, the degree of beating, the type of filler, and the amount of filler. To achieve 85% or more of whiteness, 80% of whiteness is used.
More preferably 85% or more bleached chemical pulp is used,
A white filler having a whiteness of 90% or more, preferably 95% or more is added.

As the bleached chemical pulp used in the present invention, LBKP is used because of its refining properties and the properties of fibers involved in refining.
(Hardwood bleached kraft pulp), hemp pulp (hemp pulp), flax pulp, and the like are preferred, and LBKP, hemp pulp,
Or a mixed use of these. In the case of mixed use, hemp pulp is used in a proportion of 10% by mass or more, more desirably 30% by mass or more, so that the characteristics of hemp halp can be utilized. The degree of beating of the pulp is 30 to 80 ° SR for hemp pulp and flax pulp and 30 to 70 ° SR for LBKP in view of papermaking properties. If it is less than 30 ° SR, the yield of the filler and the decrease in sheet strength become problems. If the beating degree exceeds the upper limit, papermaking becomes difficult, and problems may occur in smoothness and paper softness. In addition, LBKP has a property that whiteness decreases when beating treatment is increased to some extent, but hemp pulp and flax pulp have the property that the whiteness does not decrease even by beating treatment. A higher beating treatment than that of the LBKP alone combination is possible.

As a white filler having a whiteness of 90% or more, calcium carbonate or titanium dioxide is generally used, but calcium carbonate is most desirable in terms of cost and softness of paper. The desirable range of the amount of filler in paper varies depending on the type of pulp used, the particle size of filler particles, and the like.
It is within the range of 30% by mass (content). If it is less than 5% by mass, the effect of adding a white filler is not seen. Filler inhibits inter-fiber bonding, so filling is also preferable in reducing the strength of the paper and obtaining flexible paper having a low flexural modulus, but if the filling amount of the filler is too large, Since the strength of the paper is reduced more than necessary, the surface strength at the time of printing is reduced, and troubles such as paper waste and paper dust are likely to occur. Therefore, the amount of filler in paper is set to 30% by mass or less.

[0010] In order to realize bright whiteness of paper, it is necessary that light applied to the paper is scattered and the amount of light reflected in various directions is increased. When light hits the paper, a part is reflected in the opposite direction, and the remaining light is scattered by subtle irregularities on the paper surface, and the light entering the paper is refracted or reflected at the air-fiber interface. Is repeated, and the light is scattered and diffusely re-emitted from the inside of the paper. The amount of light scattered can be represented by the specific scattering coefficient of the paper. The special printing paper according to the present invention has a specific scattering coefficient of 50 m ² / k.
g or more.

In order to increase the specific scattering coefficient of paper, pulp having a high specific scattering coefficient is used, the specific scattering coefficient of pulp is increased, or a filler having a high specific scattering coefficient is appropriately used. The scattering ability of the paper can be increased.

[0012] The whiteness described above even in pulp having a high specific scattering coefficient
Those that do not meet the requirements of
Can not. The specific scattering coefficient of LBKP is 32.8-35.
5m ²/ Kg, the lower the beating degree, the higher the specific scattering coefficient
When the beating degree is less than 30 ° SR, the surface strength during printing is
There is a possibility that the degree will decrease and a problem may occur. Hemp pulp
Has a specific scattering coefficient of 42.9-45.3 m.²/ Kg,
In hemp pulp and flax pulp, the reverse is the case with LBKP
In addition, the specific scattering coefficient tends to increase as the degree of beating increases.
You. This is because the fiber walls of these pulp are thick and
Because the layers are easily separated as fibril bundles,
Because it increases the specific surface area of the pulp and increases the specific scattering coefficient.
is there. However, in the case of hemp pulp or flax pulp,
If the degree is higher than 80 ° SR, the problem of papermaking
Occurs, which is desirable from the economic point of
Absent.

The specific scattering coefficient of the white filler is, for example,
100-150m with clay²/ Kg, sedimentary carbonic acid
170-210m with calcium²/ Kg, heavy carbon dioxide
100-120m with sium²/ Kg, anatase diacid
400 to 550m with titanium oxide ²/ Kg, rutile dioxide
530-750m with titanium²/ Kg. Specific scattering coefficient
Specific filler by filling white paper with large filler
The random coefficient can be increased. Titanium dioxide is a specific scattering agent
The number is large but expensive, and the softness of the paper
It is also desirable to use them together with calcium carbonate.

The average particle size of the white filler is 0.1 to 5 μm.
m, preferably 0.5 to 4 μm. The specific scattering coefficient of the filler increases as the refractive index difference at the interface between air and the filler particles increases and as the area of the interface increases. Since the scattering of visible light is highest when the particle diameter is around 0.5 μm, the average particle diameter of the filler used is preferably as close to 0.5 μm. When the average particle diameter is less than 0.1 μm, the filler Not only does the specific scattering coefficient become small, but also a large amount of it flows out into white water during papermaking dewatering, causing a problem that the retention in paper becomes poor. On the other hand, if it exceeds 5 μm, the specific scattering coefficient of the filler becomes small, and the filler is liable to fall off the paper, so that a paper dust trouble is likely to occur during printing.

As described above, the amount of white filler in paper is in the range of 5 to 30% by mass, but the desired amount of filler in paper differs depending on the type of pulp used and the particle size of the filler. For example, when the used pulp is hemp pulp or flax pulp, if the white filler is calcium carbonate having an average particle diameter of about 3.5 μm, it is 7 to 30% by mass, and the average particle diameter is 0.5 μm.
If the calcium carbonate is about 7 to 20% by mass, the pulp to be used is LBKP, and if the average particle diameter is about 3.5 μm, the calcium carbonate is 17 to 30% by mass, and the average particle diameter is about 0.5 μm. In the case of calcium carbonate, the content is desirably 9 to 25% by mass. Since the specific scattering coefficient of the fiber itself is larger in hemp pulp and flax pulp than in LBKP, when these are used, a paper having the desired specific scattering coefficient can be obtained even if the amount of filler in the paper is reduced. Further, calcium carbonate having an average particle diameter of about 0.5 μm has a larger light scattering effect than calcium carbonate having an average particle diameter of about 3.5 μm, so that the amount of filler in paper can be reduced.

The specific scattering coefficient of the paper is 50-100 m ² / kg
Is preferred. When the specific scattering coefficient is less than 50 m ² / kg, the light scattering ability of the paper is low, and it is not possible to obtain whiteness or a glossy bottom. Since the scattering power of paper is obtained by adding the scattering power of filler to the scattering power of fiber, the internal addition amount of filler must be increased to increase the specific scattering coefficient of paper. In order for the specific scattering coefficient to exceed 100 m ² / kg, the amount of filler in paper must be added to more than 30% by mass.
Problems such as paper waste and paper dust during printing occur.

In order for the paper to have a good appearance, it is necessary that the smoothness of the surface of the paper is reduced so that the surface has appropriate irregularities. For this reason, a calendar process is performed as necessary so that the Beck smoothness is 60 seconds or less, preferably 40 seconds or less, and more preferably 20 seconds or less. The lower the smoothness, the better because the light scattering on the paper surface becomes stronger due to the appropriate unevenness of the surface.However, if the smoothness is too low, printing troubles such as poor ink transfer on the paper surface and picking are likely to occur. The smoothness is set to 2 seconds or more. Beck smoothness 2-60 without calendering
When seconds can be achieved, no calendaring is required.

The relative glossiness is the ratio Φ / D of the regular reflection light component Φ and the diffuse reflection light component D as measured by a surface roughness measuring method utilizing the glossiness. In other words, the relative glossiness (Φ / D) indicates the rate at which incident light is split into a regular reflection light component (Φ) and a diffuse reflection light component (D) when reflected on the paper surface. The smaller the degree is, the more the diffuse reflection light component is. As a result of the experiment, it was found that when the relative glossiness (Φ / D), which is the ratio of Φ and D measured at a light incident angle of 60 °, was 1.4 or less, the paper had a soft visual feeling. . Further, according to the experiment, the relative glossiness is affected by the whiteness, the specific scattering coefficient and the smoothness, and the greater the value of the whiteness, the smaller the relative glossiness. The influence of the specific scattering coefficient and the smoothness is not so large as the whiteness, but the contrast gloss tends to be small as the specific scattering coefficient is large, and to be small as the smoothness is low. Therefore, in the present invention, the whiteness, the specific scattering coefficient and the smoothness are set in the above-mentioned numerical ranges, and further, the beating degree of the pulp and the type of filler ( Particle size), the amount of filler in the paper, etc. must be adjusted.

When the printing paper is used for printing the text of a book, it is desirable that the page at the place where the book is opened is not changed and remains as it is, and for that purpose, the paper has a soft characteristic. It is necessary to have. It is generally considered that the texture expressed as “strain” of paper has a correlation with the product Eb ^{3 of the} cube of the elastic modulus (E) of the paper and the thickness (b) of the paper. By comparing the elastic modulus of the paper, it is possible to compare the characteristics of the softness of the paper. The bending stiffness, which is the bending load, is measured, and this is divided by the cube of the thickness of the paper to obtain the bending elastic modulus.

As a raw material pulp, the use of hemp pulp or flax pulp tends to have a lower flexural modulus than the case of using LBKP. Also,
Filling fillers such as calcium carbonate also tends to reduce the flexural modulus. The paper using hemp halp has a low flexural modulus even without calcium carbonate, and becomes a soft paper despite its bulkiness.However, as calcium carbonate is added internally, the flexural modulus is maintained while maintaining the bulkiness. It is smaller, and its value is so small that other wood pulp cannot be obtained, resulting in a very soft paper.

In printing paper, surface strength is important. Therefore, paper for printing a book text has a low flexural modulus and a high surface strength, in other words, a sheet having a low flexural modulus at the same surface strength. Paper is preferred. The book printing paper has a bending elastic modulus of 1 × 10 ⁻⁵ to 2 × 10 ^−4.
It is desirable that Paper using hemp pulp as compared to LBKP is a particularly desirable material because of its low flexural modulus at the same tensile strength.

A suitable basis weight range of the special printing paper of the present invention is 50 to 250 g / m ² , preferably 60 to 250 g / m ² .
220 g / m ² . When the basis weight is less than 50 g / m ² , the opacity of the paper becomes low, and it becomes difficult to scatter light. Although there is no particular upper limit, it is difficult to imagine a use requiring softness exceeding 250 g / m ² .

The PPS roughness (surface roughness measured using Parker Print Surf) of the special printing paper in the present invention is preferably in the range of 3 to 8 μm, and is preferably in the range of 4 to 8 μm.
7.5 μm is more preferred. If the PPS roughness is less than 3 μm, the smoothness of the paper surface is high, the specular reflection component becomes too large, and it is difficult to achieve a relative gloss of 1.4 or less, resulting in a glossy paper. Also, the PPS roughness is 8
Above μm, poor ink transfer tends to occur during printing, resulting in a rough surface and a simple feel.
It is difficult to obtain paper having the object of the present invention.

As the amount of white filler in paper increases,
The value of the Beck smoothness increases, and the value of the PPS roughness decreases, that is, the unevenness of the paper surface decreases and the smoothness tends to increase, and the printability improves. The effect of increasing the smoothness by adding the filler is more remarkable when the particle diameter of the filler is larger.

[0025]

EXAMPLES Examples of the present invention and comparative examples will be described below. In the examples and comparative examples, the following measurement methods were used.

1. Pulp beating degree (freeness): JIS
It was measured by the Shopper freeness test method in accordance with P8121-1998.

2. Filler content in paper: The ash content to indicate the filler content in paper is 5 in accordance with JIS P8128-1995.
Ash content at 75 ° C or 900 ° C was measured.

3. Basis weight: JIS P8124-1998
It measured according to.

4. Thickness: JIS P8118-1998
It measured according to.

5. Density: JIS P8118-1998
It measured according to.

6. Whiteness: JIS P8148-199
3 was measured.

7. Specific scattering coefficient S, specific absorption coefficient K: Tap
R ₀ (light reflected by a single paper specimen backed with a black body) and R, as measured by the paper opacity (paper back) test method in accordance with pi test method T425 om-91
_∞ the scattering power sW and paper obtained from (the light reflected by the backing test specimens with thick bundles of the same type of paper) basis weight W
Using (g / m ² ), the specific scattering coefficient S and the specific absorption coefficient K were determined by the following equations.

[0033]

(Equation 1)

8. Beck smoothness: JIS P8119-
It was measured according to 1998.

9. PPS roughness (surface roughness using Parker Print Surf): ISO8791-4: 1992
(E) -compliant device (PP manufactured by HE Mesmer, UK)
The clamp was measured using a soft backing at a pressure of 1960 kPa for supplying air to the clamp using S paper rough Nestester model PPS78).

10. Tensile strength: JIS P813-1
Measured according to 998

11. Flexural modulus: Tappi test method T
556 pm-95 compliant device (Lorenzen &
Wettre BENDING RESISTNANC
E TESTER), distance 5 mm, bending angle 2
Bending stiffness at 0 degrees
stiffness (Nm)) was measured to determine the bending stiffness, and this bending stiffness was divided by the cube of the sheet thickness (μm) to determine the bending elastic modulus.

12. Specular reflection light component Φ, diffuse reflection light component D, and relative glossiness (Φ / D): using a three-dimensional variable angle photometer GP-200 manufactured by Murakami Color Research Laboratory Co., Ltd., a light source halogen lamp and a light speed aperture 4.0 scale, light receiving aperture 2.0 scale, sample tilt angle 0 degree, incident angle 60 degree, light receiving range -90
Under the conditions of ~ 90 degrees and the rotation speed of the receiver of 1 degree / second,
Standard white surface 90ST sold by chnidne
The regular reflection light component Φ of D is 66 ± 0.5, the diffuse reflection light component D is 50 ± 0.5, and the relative glossiness (Φ / D) is 1.30.
The sensitivity was adjusted to be 1.34, and the specular reflection component Φ and the diffuse reflection component D of each sheet were measured to determine the relative glossiness (Φ / D).

13. Visual evaluation: "White with a glossy bottom"
In order to judge the "whiteness of the product", it is divided into "whiteness", "bottom glossiness" and "matteness" as described below, visually evaluated, and the total is summed to obtain a numerical value of the overall evaluation. And the overall evaluation of 5 or less was indicated by x, 6 to 8 by Δ, and 9 or more by で.

The degree of "whiteness" was evaluated according to the following five grades in terms of the degree to which the test piece was observed as being white when viewed from directly above (0 degrees) under room lighting. 5: Pure whiteness. 4: Almost pure whiteness. 3: A mixture of yellow and blue is slightly felt. 2: A mixture of yellow and blue is felt. 1: Colors such as yellow and blue are strongly felt.

The "base glossiness" was evaluated by irradiating the test piece with a fluorescent lamp at 60 degrees, observing the test piece from directly above, and evaluating the degree of the feeling based on the following three grades. 3: Brightness from inside the paper is strongly felt. 2: Brightness from inside the paper is felt. 1: Brightness from the surface of the paper is strongly felt.

The "matte feeling" was obtained by illuminating the test piece with a fluorescent light at 60 degrees, rotating the test piece 360 degrees in a horizontal plane, and observing the test piece from the specular reflection direction. Was evaluated. 3: No glare is sensed in all directions. 2: Glitter is slightly felt. 1: Glitter is felt. 0: Glitter is felt only in a certain direction.

Examples 1 to 11 and Comparative Examples 1 to 5 A commercially available cannabis bleached chemical pulp was used as hemp pulp (HB), and the raw material pulp beaten to a Shopper freeness of 30, 50 and 70 ° SR was internally added to each of the raw pulp. Spindle calcium carbonate (trade name PCX-85, manufactured by Shiraishi Industry Co., Ltd.)
0, average particle size of 3.5 μm) or cubic calcium carbonate (Brilliant-1 manufactured by Shiraishi Industry Co., Ltd.)
5, an average particle size of 0.55 μm), and as shown in Tables 1 and 2, a paper material without filler or a paper material internally added so that the amount of filler in paper is about 10% by mass and about 20% by mass. The sheet was prepared, paper-made using a TAPPI standard type hand-making machine, and a sheet was prepared without calendering. Tables 1 and 2 show various paper properties and luminous evaluation results of each sheet. The sheets in Table 1 have a target basis weight of 60 g / m ² , and the sheets in Table 2 have a target basis weight of 110 g / m ² or 160 g / m ² .

In Tables 1 and 2, each group (Comparative Example 1, Example 1, 2) having the same beating degree (Shopper freeness), the same basis weight, and varying the amount of filler in paper was used. Comparative Example 2, Examples 3, 4), (Comparative Example 2, Examples 5, 6),
(Comparative Example 3, Example 7), (Comparative Example 4, Example 8,
9) and (Comparative Example 5, Examples 10 and 11) show that as the filler is added and the amount of filler in the paper increases, the whiteness improves, the specific scattering coefficient increases, and the contrast gloss increases. The degree is a low value of 1.4 or less, and it can be seen that the overall luminous evaluation value is improved. When calcium carbonate having an average particle diameter of 0.55 μm was used as in Examples 5 and 6, the effect of the internal addition of calcium carbonate was more remarkable than when calcium carbonate having an average particle diameter of 3.5 μm was used. You can see that it appears.

Further, as in the groups of (Comparative Examples 1, 2, and 3), (Examples 1, 3, and), and (Examples 2, 4, and 7), the filler conditions are the same and the beating degrees are different. Comparisons within the groups show that hemp pulp does not decrease in whiteness even after the beating treatment, but has a tendency to increase the specific scattering coefficient and slightly decrease the relative glossiness by the beating.

As can be seen from Tables 1 and 2, hemp pulp has such characteristics that the whiteness is not reduced by the beating treatment and the specific scattering coefficient is increased. A paper having a low contrast gloss and a "good white gloss with bottom luster" in sight is obtained. In addition, despite the bulkiness, the surface irregularities were smaller and smoother than conventional fancy paper, and had the softness of paper, and were highly suitable as text paper for books.

Examples 12 to 16 and Comparative Examples 6 to 12 Commercially available hardwood bleached kraft pulp was used as LBKP, and each of the raw pulp beaten to a Shopper freeness of 30, 50, and 70 ° SR was filled with a white filler for internal addition. As spindle-shaped calcium carbonate (trade name PCX-850, manufactured by Shiraishi Industry Co., Ltd.)
As shown in Tables 3 and 4, using a cubic calcium carbonate (manufactured by Shiraishi Industry Co., Ltd., trade name: Brilliant-15, average particle size: 0.55 μm) Or about 10% by mass of filler in paper,
Prepare the added stock so as to have a concentration of about 20% by mass.
The paper was made with a PPI standard type hand-making machine, and a sheet was prepared without calendering. Tables 3 and 4 show various paper properties and luminous evaluation results of each sheet. The sheet of Table 3 has a target basis weight of 60 g / m ² , and the sheets of Comparative Example 12 and Example 16 in Table 4 have a target basis weight of 160 g / m ² .

In Tables 3 and 4, each group (Comparative Examples 6, 7, and 12) and (Comparative Examples 8, 9, and 12) with the same degree of beating and the same basis weight and the amount of filler in paper was varied. Example 1
3), (Comparative Example 8, Examples 14, 15), (Comparative Example 1)
0, 11) and (Comparative Example 12, Example 16) show that the whiteness is improved, the specific scattering coefficient is increased, and the relative gloss is decreased by increasing the filler amount in the paper. As can be seen, in order to obtain a sheet having a relative glossiness of 1.4 or less and a high overall luminous evaluation value, it is necessary to increase the amount of filler in the paper as compared with the above-described embodiment using hemp pulp. It turns out there is. Further, when the beating degree is 70 ° SR or more, the whiteness and the specific scattering coefficient are reduced, and the relative glossiness is 1.
4 may be exceeded.

This means that the sheet made of LBKP is
LBKP has a lower specific scattering coefficient and a higher relative gloss than a sheet made of hemp pulp, and furthermore, LBKP as shown in the comparison among the groups (Comparative Examples 6, 8, and 10) with no added filler and different beating degrees. This is because whiteness and specific scattering coefficient tend to decrease due to beating processing.
Due to such characteristics of LBKP, when using LBKP, it is necessary to lower the beating degree and to add a large amount of filler in paper. However, Example 14,
In the case of using calcium carbonate having an average particle diameter of 0.55 μm as in No. 15, the effect of the addition is remarkable, and the target sheet can be obtained even when the amount of filler in paper is about 10% by mass.

Regarding the softness of paper, LBKP tends to be a stiff sheet as compared with hemp pulp, and a sheet having a preferable softness is obtained when the amount of calcium carbonate in the paper is 20% by mass.

From the above, the sheets of Examples 12 to 16 are:
Although the softness is slightly inferior to those of the sheets of Examples 1 to 11, the whiteness, the specific scattering coefficient, and the relative glossiness are in a predetermined numerical range, and the visual feeling is “white with a distinctive bottom gloss”. Had.

Examples 17-18 and Comparative Example 13 A commercially available cannabis bleached chemical pulp as hemp pulp (HP) was mixed with a commercial hardwood bleached kraft pulp as LBKP at a mass ratio of 30/70, The raw material pulp beaten to a freeness of 70 ° SR is shown in Table 4 using spindle-shaped calcium carbonate (trade name: PCX-850, average particle size: 3.5 μm, manufactured by Shiraishi Industry Co., Ltd.) as a white filler for internal use. A paper material without filler or a paper material added so that the amount of filler in paper is about 10% by mass and about 20% by mass is prepared, and the paper is made with a TAPPI standard type hand-making machine, without being subjected to calendering. Created a sheet. Table 4 shows the various paper characteristics and the visual evaluation results of each sheet.

It is difficult to obtain the paper according to the present invention by using LBKP alone.
The sheet was beaten to 0 ° SR to produce a sheet. The tendency of LBKP showed a somewhat strong intermediate characteristic from the tendency that the density decreased as the amount of calcium carbonate filler in the paper increased, but the whiteness, When the specific scattering coefficient and the relative glossiness were within the predetermined numerical values, a sheet having a desired visual feeling was obtained, and the effect of mixing LBKP with hemp pulp was confirmed.

Example 21 Commercial hardwood bleached kraft pulp (LBKP) was beaten to a shopper freeness of 50 ° SR.
24 parts by mass of a spindle-shaped calcium carbonate (trade name: PCX-850, manufactured by Shiraishi Kogyo Co., Ltd., average particle size: 3.5 μm) as an internal filler, and an alkyl ketene dimer (AKD) -based sizing agent (Arakawa) 3.0 parts by mass of a size pine A-901 (trade name, manufactured by Chemical Industry Co., Ltd.) were blended to obtain a papermaking raw material. Using a paper machine equipped with an on-top wire in the papermaking wire section (C former) and a size press coating device in the middle of the drying section, papermaking the above papermaking raw material,
In addition, size press coating is performed, and the target basis weight is 135 g / m.
² was prepared. Size press coating is made of oxidized starch (Nippon Cornstarch Co., Ltd. product name SK-100) 4
% By mass, PVA (manufactured by Kuraray Co., Ltd., trade name PVA-11)
7) Using a coating liquid consisting of 1.33% by mass and 0.36% by mass of a surface sizing agent (trade name: PM-360, manufactured by Arakawa Chemical Industry Co., Ltd.), the solid content becomes 1 g / m ^{2 in} terms of solid content. Coated as follows. Base paper is Beck smoothness (F / W) 28 seconds / 1
The sheet according to the present invention was manufactured by performing a super calendering treatment for 6 seconds. Table 5 shows the various paper properties of the sheet and the evaluation results. Physical properties such as whiteness, specific scattering coefficient, specific absorption coefficient, and relative gloss are values measured on the F surface.

As is evident from Table 5, a high whiteness and a specific scattering coefficient, a low contrasting gloss were exhibited, and a sensation of white gloss, a bottom gloss and a matte sensation were also felt.
The special printing paper of the present invention having "good and bottom glossy whiteness" was obtained. Regarding the softness of the paper, the bending elastic modulus in the transverse direction (perpendicular to the papermaking direction), which is important as the text paper, was in an appropriate range and was sufficiently soft.

Further, as is apparent from the PPS value, the special printing paper of the present invention exhibited the same surface roughness despite being bulkier than the high-quality paper having the same basis weight shown in Comparative Example 16, and exhibited excellent printing. It had suitability.

Comparative Examples 14 to 17 As Comparative Example 14, commercially available special printing paper, trade name: Super Contrast (manufactured by Tokushu Paper Co., Ltd., basis weight 115 g /
m ² ), the same as Comparative Example 15 under the trade name Araber (Nisshinbo Industries, Ltd., basis weight 127.9 g / m ² ), Comparative Example 16
Commercially available high quality paper, brand name OK fine quality (Oji Paper Co., Ltd.)
Ltd., basis weight 127.9 g ^{/ m} 2), matt coated type of coated printing paper as a comparative example 17, using the product name U-LITE (Nippon Paper Industries, basis weight 127.9 g / ^{m 2),} of Table 5 shows the properties of the various papers and the results of the visual evaluation.

Comparative Example 14 was soft and had appropriate whiteness, Bekk smoothness, and relative gloss, but had a low specific scattering coefficient, and the visual evaluation was mixed with whiteness. The value was inferior. Comparative Example 15 is slightly rigid, has a low specific scattering coefficient, has a relatively large contrast glossiness, and is out of an appropriate range. Directional glare due to fine irregularities was felt. Comparative Examples 16 and 17 were rigid, had a low specific scattering coefficient, had high smoothness, had a considerably high relative glossiness, and felt a strong glare. Further, in Comparative Example 17, cold whiteness due to the fluorescent dye was felt. Comparative Examples 15, 16, and 17 all had considerably poor luminous overall evaluation values.

[0059]

[Table 1]

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

[Table 4]

[0063]

[Table 5]

[0064]

According to the present invention, there is provided a special printing paper having a soft appearance and a whiteness, which is flexible when used in the body of a book, such as suppleness and ease of opening pages. And a paper having excellent printability is provided.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junyuki Hattori 90-2 Eo, Fuji City, Shizuoka Prefecture Inside Mishima Paper R & D Laboratories (72) Inventor Keishi Hara 6-16-12 Ginza, Chuo-ku, Tokyo Mishima Product 4L055 AA03 AA07 AC06 AG12 AH01 EA11 EA12 FA12 GA15

Claims (8)

[Claims] 1. A whiteness of 85% or more and a Beck smoothness of 2
紙 / D is a ratio Φ / D of the regular reflection light component Φ and the diffuse reflection light component D when the specific scattering coefficient is 50 m ² / kg or more and measured at an incident angle of light of 60 °. A special printing paper having a relative gloss of 1.4 or less. 2. A paper prepared by internally adding a white filler having a whiteness of 90% or more to bleached chemical pulp having a whiteness of 80% or more, and adjusting the Beck smoothness to 2 to 60 seconds. A relative gloss of 85% or more, a specific scattering coefficient of 50 m ² / kg or more, and a ratio Φ / D of a regular reflection light component Φ and a diffuse reflection light component D when measured at an incident angle of light of 60 °. A special printing paper having a degree of 1.4 or less. 3. The special printing paper according to claim 1, wherein the bleached chemical pulp is at least one selected from hemp pulp, flax pulp and LBKP. 4. A white filler having a filler content in paper of 5 to 30% by mass.
The special printing paper according to claim 1, wherein: 5. The special printing paper according to claim 1, wherein the white filler comprises calcium carbonate. 6. The calcium carbonate has a particle size of 0.1 to 5 μm.
The special printing paper according to claim 5, wherein m is m. 7. The paper has a flexural modulus of elasticity of 1 × 10 ⁻⁵ to 2 ×.
The special printing paper according to claim 1, wherein the printing paper is 10 ^-4 . 8. The special printing paper according to claim 1, wherein the specific scattering coefficient is 50 to 100 m ² / kg.