JPH09176986A - Filler added paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a filler added paper having a high after printing opacity while maintaining surface strength thereof. SOLUTION: This filler added paper is obtained by providing a coated layer of an outside filler having 0.01-0.4g/m<2> coating amount per one side surface on the support raw material paper containing a pulp and a hydrated silicic acid satisfying the following particle characteristics of (A) to (C): (A) 250-350ml/100g oil absorbing amount; (B) 4.0-6.0cc/g total pore volume and a mean pore radius is in the range of 200-400Å; and (C) a mean particle diameter is in any of the ranges of 3.0-15μm measured by a laser method, 2.0-4.0μm measured by a Coulter method and 0.5-3.5μm measured by a centrifugal sedimentation method. Further, Bekk smoothness is preferably in the range of 25-200sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper containing a filler internally, and more particularly to a paper having an excellent opacity after printing and a high surface strength during printing.

[0002]

2. Description of the Related Art From the standpoint of protecting forest resources and reducing environmental load including the problem of garbage, it is necessary to reduce the weight of paper. This is because the weight reduction reduces the weight of wood fibers required to transmit the same amount of information, and the amount of waste also decreases. Especially for newsprint, the basis weight is 50g / m ² to 43,
Some have moved to 40 or less. In such weight reduction, the optical properties of the paper, particularly the opacity and the opacity after printing, deteriorate, and so-called "strikethrough" becomes a problem. This problem applies not only to newsprint paper, but to general lightweight printing paper as well, but these papers are bulky (thickness) due to their light weight.
Is also a big problem. Conventionally, hydrated silicic acid called white carbon and calcined clay have been used to solve these problems. The hydrated silicic acid for internal addition is a porous filler having a primary particle size of about 0.01 to 0.05 μm, and usually agglomerates to a higher degree and has a particle size of 5 to 10 μm when measured by a Coulter counter. Since it has excellent properties, it is effective in preventing strike-through caused by the penetration of oil-based printing ink. However, since the particle size is relatively large, the ability to scatter incident light is low. That is, although the ability to maintain the opacity after printing is maintained, the ability to improve the opacity of white paper is small. On the other hand, other internal fillers for papermaking typified by titanium dioxide have a small particle size and a high ability to scatter light, but a low ability to suppress penetration of printing ink. Usually, printing paper such as newsprint is added with these fillers so as to satisfy the required quality.

[0003]

However, when the weight is extremely reduced as described above, the conventional filler cannot maintain the opacity after printing. Further, the filler such as white carbon has a large particle size, so that interfiber bonding is significantly hindered, resulting in a decrease in surface strength. The present invention focuses on the fact that hydrated silicic acid having a large pore volume and extremely fine particle properties is superior to the existing hydrated silicic acid and hydrated silicate in the effect of preventing strike-through of paper, and this filler is added. This provides a paper having high opacity after printing while maintaining the surface strength.

[0004]

As a result of intensive studies to solve the above-mentioned problems, as a result, 0.01% of external additive was added to one side of a support base paper made of hydrated silicic acid having specific particle characteristics and pulp. The present invention was found to be able to obtain a filler-containing paper with high opacity after printing and excellent surface strength during printing by applying a coating amount of up to 4.0 g / m ² .

The hydrated silicic acid used to achieve the above object is a hydrated silicic acid obtained by neutralizing an aqueous sodium silicate solution with a mineral acid, and has an oil absorption of 250 to 350 ml / 10.
0 g, the total pore volume is 4.0 to 6.0 cc / g, and the average pore radius is in the range of 200 to 400 Å,
And the average particle size is 3.0 to 1 as measured by the laser method.
5 μm, measured by Coulter method: 2.0 to 4.0 μm
m or 0.5 to 3.5 μm as measured by the centrifugal sedimentation method
The constitutional feature is to have a particle characteristic in any one of the ranges.

The characteristic values of the hydrated silicic acid according to the present invention are based on the values obtained by the following measuring methods.

(1) Oil absorption; according to JIS K5101 (2) BET specific surface area; powdered hydrated silicic acid sample 0.0
5 to 0.1 g of "Flow soap 23 manufactured by Shimadzu Corporation
00S / N type "and degassing condition at 300 ° C for 30 minutes.

(3) Total pore volume: 0.05 g of a powdery hydrated silicic acid sample was degassed under vacuum for 30 minutes, and then mercury was injected,
The pore volume is increased by pressurizing from 1 to 1900 bar to obtain a mercury porosimetry method (apparatus used: Carlo Erba Co., Ltd., mercury porosimeter 20).
Type 0). The measuring pressure corresponds to a pore radius of 75000 angstroms to 39 angstroms.

(4) Average pore radius; determined from the specific surface area S and the total pore volume V obtained during the measurement of the total pore volume as a value calculated by radius (r) = V / S.

(5) Particle size distribution measurement; (a) Laser method; A sample slurry of hydrated silicic acid was added drop-wise in pure water to which 0.2% by weight of sodium hexametaphosphate dispersant was added to form a uniform dispersion. Particle size measurement is performed using a method particle size measuring device [apparatus used; manufactured by Nikkiso Co., Ltd., "Microtrack 9220FRA type is used].

(B) Coal tar method: A sample of hydrated silicic acid slurry was added dropwise to 3 drops of 50 ml of pure water containing 0.2% by weight of sodium hexametaphosphate and ultrasonically dispersed for 3 minutes to prepare a uniform dispersion as Coulter Counter TA type. (Coulter Electronics Co., Ltd.) is used to measure the particle size.

(E) Centrifugal sedimentation method: A sample hydrated silicic acid slurry is dropped into a pure water solution containing 0.2% by weight of sodium hexametaphosphate and measured as a measurable concentration (apparatus used: "micron manufactured by Seishin Enterprise Co., Ltd." Photosizer SK
N-1000 type "is used.) A portion having a particle diameter of 1 ml or less is measured by centrifugation, and a portion having a particle diameter of 1 ml or more is measured by gravity sedimentation.

The particle properties of the finely hydrated silicic acid according to the present invention are as follows:
First, it is characterized by a total pore volume of 4.0-6.0 cc / g and an average pore radius in the range of 200-400 Angstroms. This total pore volume is at a higher level than that of hydrated silicic acid obtained by a conventional method of wet-milling a reaction-completed slurry, which is 4 cc / g or less, and has a porous structure. . Therefore, when it is used as a filler for paper, it effectively absorbs the ink liquid and thus functions effectively. If the total pore volume is less than 4.0 cc / g, the absorption capacity is insufficient and the strike-through preventing effect is not effectively imparted, and if it exceeds 6.0 cc / g, other properties are impaired. Invite.

This total pore volume is related to the pore radius of the pores distributed in the tissue, but in practice the pore radius is 100.
Since the adsorption equilibrium water is always filled in the micropores smaller than angstrom, it does not function for adsorption, and the adsorption power becomes weaker than 104 angstroms and does not contribute to the adsorption ability. The hydrated silicic acid of the present invention having a total pore volume in the range of 4.0 to 6.0 cc / g has an average pore radius of approximately 100 to 40.
In the range of 0 Å (center pore radius of 50% pore volume is 1500 to 3500 Å),
It is located in the range of superior adsorptivity compared to conventional hydrated silicic acid. Therefore, it is suitable not only for paper fillers but also for various applications as described later.

The second requirement for the particle characteristics of the finely hydrated silicic acid according to the present invention is that the average particle size of the finely hydrated silicic acid is 3.0 to 15 μm as measured by the laser method, and the average particle diameter is as measured by the Coulter method. It is a point in any range of 2.0 to 4.0 μm or 0.5 to 3.5 μm as measured by the centrifugal sedimentation method. The particle size of hydrated silicic acid shows different measured values depending on the laser method, the Coulter method, and the centrifugal sedimentation method. This is thought to be because the silicic acid particles are porous and strongly hydrated. The hydrated silicic acid according to the invention is characterized in that it is finer particles than conventional ones, and tends to take a particularly small value when measured by the centrifugal sedimentation method. Further, the reason why the value is relatively large in the measurement by the laser method is that particles having a size of 1 μm or less tend to be transparent and cannot be detected, which is significant for evaluating the particle size of relatively large secondary particles. . Further, the hydrated silicic acid according to the present invention has an oil absorption of 250 to 3 in combination with the above-mentioned particle characteristics.
Another feature is that it is in the range of 50 ml / 100 g, which is a value relatively larger than the conventional one. This characteristic is also one of the preferable characteristics as a paper filler.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A hydrated silicic acid having the above-mentioned particle properties is produced by adding mineral acid to an aqueous solution of sodium silicate to produce hydrated silicic acid by a neutralization reaction.
After addition the reaction system temperature below the boiling point of ₂ as a 6-10% by weight of sodium silicate in the neutralization equivalent of the amount of mineral acid equivalent to 30 to 50% 70 ° C. or higher, a strong shearing force within the aging time First to perform a thorough wet crushing process based on
The second step in which a substantial amount of the mineral acid is added at a temperature higher than the temperature of the step and the previous step and the mixture is aged to precipitate almost all the amount of silica, and the pH of the slurry is adjusted to 5 by adding the mineral acid. It is manufactured by a process consisting of a third step of adjusting to the range of 3.

The first step is a step of adjusting the concentration of an aqueous solution of sodium silicate and heating it, adding the first stage mineral acid, and performing wet pulverization and aging. Sodium silicate solution is SiO ₂ / Ma ₂ O
It is preferable that the molar ratio is 2.9 to 3.4, and the silica concentration must be set in the range of 6 to 10 weight percent. If the silica concentration exceeds 10 weight percent, uniform stirring cannot be performed when the viscosity increases during the first step, and silica having good particle characteristics cannot be obtained. At a low concentration below 6 weight percent, the production efficiency deteriorates.
The concentration-adjusted sodium silicate solution is heated from 70 ° C. to a temperature range below the boiling point of the solution. If the temperature is lower than 70 ° C., the deposition rate of silica becomes slow and it takes a long time to complete the reaction in the first stage.

Sulfuric acid is preferably used as the mineral acid for the neutralization reaction. The concentration of sulfuric acid is not particularly limited, but if it is too thin, the reaction system becomes thin and the capacity becomes too large, which is not industrial. The high concentration of 98 percent sulfuric acid has a large calorific value and can be used energetically favorably if sufficient mixing can be performed at the addition position. The addition amount of the mineral acid in the first step is 35 to 5 which is the neutralization equivalent of sodium silicate.
Set in the range of the amount corresponding to 0%. This addition amount range is related to the structural properties of hydrated silicic acid, and even if it is less than 35% or more than 50%, the high structural property of the precipitated silica is impaired and the strikethrough is prevented when it is used as a filler for paper. Effectiveness and yield are reduced. The time required for the addition is relatively short for 5 to 20 minutes, and it is preferable to complete the addition before the precipitation of silica. Further, the higher the temperature and the concentration of silica, and the larger the amount of mineral acid added, the more the silica is deposited in a shorter time, so it is desirable to adjust the addition rate according to these conditions. If added within 5 minutes, the constitution of a uniform reaction system becomes insufficient.

In the first step, a particularly important operating requirement is that, in addition to the above reaction conditions, the addition of mineral acid is followed immediately by thorough wet milling based on strong shear forces. The wet crushing has a crushing effect even after the silica is precipitated after the addition of the mineral acid, but it is preferable to start the precipitation of silica or immediately before that. According to the research conducted by the inventors, it was found that crushing from the beginning of precipitation is effective. Therefore, the crushing will proceed at the same time as the aging treatment performed after the addition of the mineral acid. This process step in the prior art is called a maturation operation, and was usually applied only to promote the precipitation of silica by continuing the normal stirring operation under heating for a predetermined time. By carrying out thoroughly, the reaction system becomes extremely uniform, and the pulverization efficiency is remarkably improved to produce preferable particles. The aging time varies depending on the temperature, but it is 80 ℃
2 to 3 hours, and 90 ° C for 1 to 2 hours. The wet crushing is completed within the aging time and is not performed after the second step. Therefore, the aging in this step will occur between the complete milling process after partial neutralization.

Here, thorough wet pulverization means an operation of using a pulverizer or a disperser capable of applying a strong shearing force to prevent the agglomeration of silica particles produced as much as possible. Therefore, depending on the crusher used, it is desirable to continuously and repeatedly perform crushing treatment throughout the aging time. It is particularly preferable that the silica particles (dispersion degree) produced in this step have an average particle diameter of 2.0 to 1.0 μm by the Coulter method.

As a crusher used for wet crushing, a ball mill in a broad sense such as a ball mill and a rod mill, a medium agitating crusher such as a tower mill, an attritor, a sately mill, a sand grinder, and an annula mill, a colloid mill, a homomixer, an in-line mill, etc. The high-speed rotary crusher and the like. Since the silica particles precipitated in the present invention are extremely fine, and particularly the silica precipitated in the first step is easily crushed, it can be crushed with a disperser or an emulsifier in addition to the crusher described above. Can be used in combination with a crusher.

In the second step, while maintaining the slurry temperature from 80 ° C. to the boiling point of the solution or lower, at a temperature of the temperature of the previous step or higher, a substantial residual amount of mineral acid is dividedly added as a second stage and almost the entire amount is added. In this step, the silica is deposited to strengthen the connection of the silica particles deposited in the first step. That is, it is preferable to control the neutralization rate by the mineral acid in this step so that the neutralization rate is 80 to 95% as the first-stage addition, and the addition is performed over about 15 to 30 minutes. After the addition, in order to complete the reaction, it is preferable to perform aging for a while under normal stirring.

The particle size of the final hydrated silicic acid after the second step is surprisingly substantially the same as that after the first step. As described above, the fact that the particle diameter does not change in the second step means that nucleation, particle growth, particle aggregation in the first step,
This shows that the hydrated silicic acid having a high structure having the above-mentioned characteristics is synthesized by the smooth progress of the control of the aggregate diameter by thorough wet pulverization and the strengthening of the bond in the aggregated particles in the second step. Therefore, the crushing process after the second step is not performed. The reason for this is that it breaks the highly structured silica structure that has been formed. Further, the slurry viscosity is high in the stage of the first step, but after the second step, the slurry viscosity is reduced to about 1/5, which is advantageous for handling.

The third step is a step of adjusting the pH of the slurry to a range of 5 to 3 by further adding a mineral acid subsequent to the second step. The addition of the mineral acid at this stage causes the pH component to return due to the elution of the alkaline component contained in the hydrated silicic acid, and since the change in this pH range is large, it takes about 60 to 60 minutes to slowly add the acid. It is preferable to carry out. Therefore,
The operation difference between the second step and the third step is only the addition rate of the mineral acid, and the other conditions are substantially the same. It is also a good idea to use low concentrations of sulfuric acid to precisely adjust the pH. Note that the addition of the mineral acid here is exclusively for adjusting the pH of the reaction system and the reaction is substantially completed in the previous step. Therefore, the addition amount is usually at most 20 of the neutralization equivalent.
%, Preferably about 5%. Operationally, this is a gentle addition process with some interruption in view of the relationship with the previous process.

The hydrated silicic acid obtained in the third step is
Since sodium sulfate produced as a by-product may be mixed, it is preferable to perform filtration, washing with water and repulp treatment.

The hydrated silicic acid according to the present invention is as described above.
Even if it is contained in a small amount in paper, it has a high effect of preventing strike-through due to its high absorption of printing ink. That is, when blended in paper, it improves opacity after printing. However, blending not only the hydrated silicic acid according to the present invention but also an inorganic filler having no interfiber bonding ability into the paper causes a decrease in surface strength related to printability. As a general means for improving the surface strength, a method using a paper-strengthening agent such as a cationized polyelectrolyte or a method of lowering the filtered water of pulp to enhance the interfiber bond can be considered, but these methods are not efficient. It is low and has the drawback of changing the properties of the paper itself. Therefore, the present inventors have a large pore volume,
Also, paying attention to the fact that hydrated silicic acid with extremely fine particle properties has a better show-through prevention effect than existing hydrated silicic acid and hydrated silicates, and by adding this filler, opacity after printing while maintaining surface strength As a result of earnest research on a paper with a high filler content, it was found that the surface strength can be dramatically improved by applying a specific amount of an external additive, and the present invention has been completed.

That is, according to the present invention, the hydrated silicic acid according to the present invention is blended in an amount of 0.05 to 25.0% by weight, so that the opacity after printing is dramatically improved as compared with any conventional filler having the same opacity. Improve. When the blended amount of the hydrated silicic acid according to the present invention is 0.05% by weight or less, the opacity after printing is low, and even if it is blended by 10.0% by weight or more, the improvement effect becomes low, and 15.0% by weight or more. In the case of the compounding ratio, only the same effect as the compounding ratio below that is exhibited. However, increasing the blended amount of the hydrated silicic acid according to the present invention increases the bulk of the paper and the oil absorption amount. Therefore, if it is not necessary to improve the opacity after printing, the blending amount of 15% by weight or more is possible. is there. According to the present invention, the support base paper produced in this manner is used for the production of oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, carboxymethyl cellulose, latex, casein, polyvinyl alcohol, polyacrylamide and its derivatives. By applying any of the external additives, or a mixture thereof, with a gate roll coater, bar blade coater, blade coater, air knife coater, size press, etc., while maintaining surface strength, the filler with high opacity after printing It is possible to manufacture attached paper. In this case, at least 0.01 g / m ^{2 on} one side is required to improve the surface strength as the coating amount, but if the coating amount is too large, the drying property of the printing ink deteriorates and the opacity decreases. A coating amount of 4.0 g / m ² or less on one side is desirable because it has an adverse effect.

Particularly, when the purpose of use of the paper is offset printing such as newspapers, if the smoothness of the paper is too low, the ink transferability is poor, the print quality is deteriorated, and if the smoothness of the paper is too high, the ink transferability is deteriorated. Becomes too high, which causes deterioration of opacity after printing, poor ink drying, deterioration of running property, and deterioration of surface strength. In order to adjust the ink transferability within the practical range and optimize the opacity after printing, after applying an external additive, the Beck smoothness is 25 to 20 with a machine calendar or a soft calendar.
It is necessary to adjust to 0 second, preferably 30 to 100 seconds.

The hydrated silicic acid according to the present invention has a total pore volume of 4.0 to 6.0 cc / g and an average pore radius of 200 to 40.
2. While having a high level of porous structure in the range of 0 angstrom, the average particle size is measured by a laser method.
0 to 15 μm, measured value by Coulter method is 2.0 to
4.0 μm or 0.5 to 0.5 as measured by centrifugal sedimentation method
It is in any fine range of 3.5 μm, and particularly when applied as a filler for paper, it exhibits a weight reduction and an excellent effect of preventing strike-through, and exhibits a high filler yield. Therefore, in many cases, the specific surface area is in the range of 100 to 200 m ² / g, and the oil absorption amount is 250 to 350 ml / 100 g, which is a unique particle characteristic showing a relatively high value. Further, the hydrated silicic acid according to the present invention is blended in an amount of 0.05 to 25.0% by weight, and the raw paper made into paper is oxidized starch, hydroxyethyl etherified starch, enzyme-modified starch, latex, polyvinyl alcohol, polyacrylamide and its derivatives, etc. By applying any of the external additives, or a mixture thereof, and especially when the purpose of the paper is offset printing for newspapers, after applying the external additive, use a machine calendar, a soft calendar, or the like. By adjusting Beck's smoothness to 150 seconds or less, preferably 30 to 90 seconds, it is possible to manufacture a paper having high opacity after printing while maintaining the surface strength during printing. In order to improve the surface strength, the coating amount in this case is at least 0.01 g / m ^{2 on} one side.
However, if the coating amount is too large, the drying properties of the printing ink may be deteriorated and the opacity may be deteriorated. Therefore, a coating amount of 4.0 g / m ² or less on one side is desirable. As the external additive, in addition to the above, conventionally used carboxymethyl cellulose, casein and the like may be used.

[0030]

EXAMPLES Examples of the present invention will be specifically described below in comparison with comparative examples. In addition, in measuring the properties of hydrated silicic acid, the total pore volume was measured by a mercury porosimeter 200 manufactured by Carlo Erba Co.
Type 0, laser method average particle size is Microtrac 9220FRA manufactured by Nikkiso, Coulter method average particle size is Coulter Electronics Coulter Counter TAII, centrifugal sedimentation method average particle size is Micro Photosizer SKN manufactured by Seishin Enterprise Co., Ltd. Each of -1000 was used, and the printability evaluation such as opacity (strikethrough) and surface strength of the paper after printing was performed by the following method.

Evaluation of printability of paper: NYKP: T was used as a papermaking raw material by a pilot paper machine manufactured by Suzuki Wood Machinery Co., Ltd.
MP: GP: DIP = 20: 30: 20: 30 using a pulp slurry with a mixing ratio, using the filler slurry obtained in each example as a filler, basis weight 40 g / m ² , ash content in paper 1 to 4 weight percent The paper was made into the following paper, dehydrated with a press, and dried with a cylinder dryer to prepare a base paper sample. This base paper sample was coated with an external additive using a laboratory gate roll coater manufactured by Mitsubishi Heavy Industries, dried with a scuff dryer, machine-calendered and adjusted to a specified smoothness to obtain a wound sample. This roll-up sample is a Didede Web PressCorporation
Newspaper ink for keyless offset [Toyo Ink Co., Ltd. New King]
VANTEAN black] was used to perform single-sided printing with a print surface density of 1.0 and continuous 10,000 copies. After leaving it in an atmosphere of 20 ° C. and 65% RH for 24 hours, the reflectance of the printed back surface was measured with a Macbeth reflection densitometer, and the strikethrough value (opacity after printing) was calculated by the following formula.

Strikethrough value = (Reflectance of printed back surface / Reflectance of unprinted back surface) × 100 (%) The strikethrough value and opacity (JIS) of the sheet sample prepared by adding the filler slurry of Comparative Example 1. (According to P8138) as a reference, and the increase values from that value were taken as the strikethrough improving effect and the opacity improving effect, respectively.

Further, the deposit on the blanket after printing 10,000 copies of the wound sample was thoroughly scraped and collected with a spatula-shaped instrument for 100 cm ² , dried in a desiccator containing a desiccant for one day and then weighed. The value was divided by the collection area to give the amount of paper dust (mg / cm ² ).

Production Example of Hydrated Silicic Acid Slurry Commercially available No. 3 sodium silicate (SiO ₂ : 20.
0%, Na ₂ O: 9.5%) was diluted with water to prepare a 6.7 weight percent diluted sodium silicate solution as SiO ₂ . First, as a first step, this sodium silicate solution is heated to 90 ° C.
After heating to 70 ° C., sulfuric acid (concentration: 95% by weight) in an amount corresponding to 40% of the neutralization equivalent was added over 7 minutes under sufficient vigorous stirring that does not generate a coarse gel. The liquid after the addition of sulfuric acid was transparent and no solid matter was observed. After the addition was completed, the resulting partially neutralized solution was transferred to a high speed rotary pulverizer type mixer. During this liquid transfer, a large amount of silica was deposited to form a slurry. The grinding process was carried out for 2 minutes. After the pulverization, the slurry was returned to the original reaction vessel, the temperature was reheated to 90 ° C., and the mixture was maintained for 2 hours under stirring for aging. A minute amount of the slurry after completion of aging was sampled and the particle size was measured by the Coulter method.

Next, in the second step, the slurry temperature is set to 9
The temperature was raised to 5 ° C., sulfuric acid having the same concentration as in the first step was added to 85% of the neutralization equivalent over 15 minutes, and aged for 15 minutes.

Subsequently, in the third step, 1N sulfuric acid was added to the aged slurry over 30 minutes to adjust the slurry pH to 4.5.

After the completion of the third step, the slurry was filtered and washed with water, and a 10 wt% slurry of hydrated silicic acid repulped in pure water was recovered. The resulting slurry was filtered and dried to measure the total pore volume, average pore radius, BET specific surface area and oil absorption. The results are shown in Table 1 in comparison with the applied variable conditions.

Example 1 The obtained hydrated silicic acid slurry was added except that Examples 8 and 9 were added so that the ash content in the paper was 2% by weight, and a base paper sample obtained by papermaking was treated with oxidized starch (manufactured by Nippon Corn Starch). SK20) was applied by a pilot gate roll coater so that the coating amount on one side was 0.5 g / cm ² , and then a winding sample was prepared by adjusting the Beck smoothness to be 50 seconds by a machine calendar. An offset printing test was conducted on the obtained wound sample, and the strike-through value and the amount of paper dust were measured and shown in Table 1.

Example 2-4, Comparative Example 4 Except that the Bekk smoothness was adjusted to 25, 90, 150, and 200 seconds in the production of the wound sample of Example 1, except that
A wound sample was prepared under the same conditions. The obtained wound sample was subjected to print evaluation in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Example 5-8 In preparation of the wound sample of Example 2, 0.5 g / m of hydroxyethyl etherified starch (PG280 manufactured by Penford Products Co., Ltd.) was used in place of the oxidized starch.
² (one side), PVA (polyvinyl alcohol, PVA105 made by Kuraray) 0.1 g / m ² (one side), latex (Penford Products, pen size) 0.1
g / m ² (one side), PAM derivative (made by Hoshiko Kagaku Kogyo, X
Coat) 0.07 g / m ² (one side)
Other than that, the winding sample was produced under the same conditions. The obtained wound sample was evaluated for printing in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Example 9, Comparative Example 5 In the preparation of the wound sample of Example 1, a 2-roll size press for experimentation was used in place of the gate roll coater and hydroxyl ethyl etherified starch (Penford Products) was used in place of oxidized starch. Manufactured by PG27
0) 4 g / m ² (one side), high-viscosity hydroxyl-ethyl etherified starch (manufactured by Penford Products,
PG260) was coated on each side at 6 g / m ² (one side), and other than that, a winding sample was prepared under the same conditions. The obtained wound sample was evaluated for printing in the same manner as in Example 1, and the results are shown in Tables 2 and 3 together.

Examples 10 and 11 In the preparation of the base paper sample of Example 1, the filler content in the hydrated silicic acid according to the present invention in the paper was set to 25% by weight and 30% by weight, respectively, and otherwise the same conditions as in Example 9 were used. Then, a winding sample was prepared. The obtained winding sample was evaluated for printing in the same manner as in Example 1, and the results are also shown in Table 2.

Comparative Example 1 A hydrated silicic acid slurry was produced under the same conditions as in the same production example except that the pulverization treatment in the first step in the production example of the hydrated silicic acid slurry was not carried out. A base paper was prepared from the obtained slurry under the same conditions as in Example 1. The obtained base paper was coated in the same manner as in Example 1, the print evaluation was performed, and the results are also shown in Table 3.

Comparative Example 2 In the preparation of the wound sample of Example 1, water was applied in place of the starch, and the wound was manufactured under the same conditions. The winding sample thus obtained was evaluated for printing in the same manner as in Example 1, and the results are also shown in Table 3.

Comparative Example 3 The base paper of Comparative Example 2 was coated with water instead of starch,
Other than that, the winding was produced under the same conditions. Printing evaluation was performed on the obtained wound sample in the same manner as in Example 1,
The results are also shown in Table 3.

From the results shown in Tables 1, 2 and 3, the hydrated silicic acid of the examples satisfying the requirements of the total pore volume and the average particle size according to the present invention are the same as Comparative Examples 1 and 3 which are standard. As compared with the above, it can be seen that the effect of preventing strike-through is excellent and that the opacity is improved, and that applying the coating increases not only the opacity after printing but also the surface strength during printing. In this case, since the opacity, which is an excessive coating amount, is remarkably reduced as seen in Comparative Example 5, the upper limit of the coating amount is preferably about 4 g / m 2 on one side as shown in Example 9. Further, since the excessive smoothness seen in Comparative Example 4 causes a decrease in opacity and a decrease in surface strength in newspapers and the like, the upper limit of the smoothness is Beck smoothness of 150 seconds shown in Example 4, and preferably It is 90 seconds or less shown in Example 2, and the lower limit is 25 seconds or more shown in Example 2. Furthermore, as shown in Examples 10 and 11, the hydrated silicic acid according to the present invention was improved in opacity and opacity after printing as much as it was added to the paper, but the surface strength was significantly lowered. ,
Since the limit of the filler in the paper is 25% by weight shown in Example 10, in order to improve the opacity and the opacity after printing while maintaining the surface strength, the range of the filler ratio in the paper is 0.
05 to 25 weight percent.

[0047]

As described above, the internal filler of the present invention is
While maintaining the surface strength during printing, not only the opacity after printing but also the opacity of white paper is high. Therefore, it is not only a major contributor to the paper manufacturing industry, but by using this filler-containing filler paper, it is possible to reduce not only the opacity of the filler component after printing but also the opacity of white paper while reducing the wood resource pulp. Is possible, and as a result, it is extremely large that it contributes to forest resources and environmental protection. In addition to newsprint, the filler inner paper using the hydrated silicic acid of the present invention is, for example, general high-quality or medium-quality printing paper, lower grade paper, base paper of coated paper, PPC.
Paper, foam paper, ink jet paper, thermal paper base paper, carbonless paper base paper, etc. are also included.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

[Table 3]

Claims (2)

[Claims] 1. A pulp and the following A to C: A. The oil absorption amount is 250 to 350 ml / 100 g, and B. The total pore volume is 4.0 to 6.0 cc / g and the average pore radius is in the range of 200 to 400 angstroms; The average particle size is 3.0 to 1 as measured by the laser method.
5 μm, measured by Coulter method: 2.0 to 4.0 μm
m, the value measured by the centrifugal sedimentation method is in the range of 0.5 to 3.5 μm, and 0.01 to 4.0 g per side on a support base paper containing hydrated silicic acid satisfying the particle characteristics of Internal filler paper with a coating layer of external additive having a coating amount of / m ² . 2. The offset printing paper according to claim 1, wherein the Bekk smoothness is in the range of 25 to 200 seconds.