JP2007091581A - Porous filler, its production method and paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a porous filler which has high subliming effect when being blended into paper, can increase the opacity of white paper as well, further has a suitable average particle diameter and a narrow particle diameter distribution, and can increase the surface strength and internal joining strength of the paper, and to provide a method for producing the same. <P>SOLUTION: The porous filler comprises: silicon-containing particles formed of silicon dioxide and/or silicate; and alkali resistant fine particles of 0.1 to 24 pts.mass to 100 pts.mass of the silicon-containing particles. In the method for producing the porous filler, alkali resistant fine particles are added to an alkali silicate aqueous solution, thereafter, a solution of mineral acid and/or a solution of the metal salt of mineral acid is added thereto, and neutralization is caused, so as to precipitate silicon-containing particles. The amount of the alkali resistant fine particles to be added is 0.5 to 30 pts.mass to 100 pts.mass of the silicon-containing particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a porous filler used for increasing the bulk of paper and a method for producing the same. The present invention also relates to a paper containing a porous filler.

  Paper is desired to be reduced in weight from the viewpoints of resource saving and logistics cost reduction, and social demands such as an increasing environmental protection movement. However, when the paper is lightened, the paper thickness is reduced, the opacity is lowered, and the printing on the back side is transparent. Thus, there is a problem that not only it is difficult to read but also the high quality of the paper is impaired. Therefore, it is required to reduce the weight while maintaining the thickness of the paper, that is, to increase the bulk.

Examples of methods for increasing the bulk of the paper include, for example, a method of appropriately selecting wood pulp, which is the main raw material of paper, a method of beating pulp, a mercerization treatment or an enzyme treatment, and a wet press pressure or a smoothing treatment pressure applied during papermaking. A method of relaxing, a method of adding a bulking agent such as a surfactant to the pulp, and the like are known.
However, in these methods, there is a problem that the paper cannot be made sufficiently bulky, and when a bulking agent is used, foaming occurs during paper making.

Therefore, a method of adding a filler having a small bulk specific gravity has been proposed. For example, a method of blending a filler having a high aspect ratio such as needle-like, columnar, or squirrel-like calcium carbonate (see Patent Document 1), a method of blending a hollow synthetic organic capsule (see Patent Document 2), amorphous silica or A method of blending a porous filler such as regular silicate and zeolite (see Patent Document 3) has been proposed.
However, fillers with a high aspect ratio, such as needle-like, columnar, and tiger-like calcium carbonate, have a lower bulk specific gravity as the particle size increases. However, when such fillers are added to paper, the share at the time of papermaking is reduced. In fact, the aggregate structure is destroyed by a mechanical load such as a roll nip, and a sufficient bulking effect cannot be obtained.
In addition, hollow particles such as hollow plastic pigments have an excellent bulking effect, but are expensive and difficult to apply to versatile printing paper.

Porous fillers are superior in paper bulking effect and have better ability to absorb ink components during printing than other fillers, but have the ability to increase paper opacity compared to calcium carbonate and talc. It was low. In addition, since the particle size is large and the particle size distribution is broad, the surface strength is poor, causing problems such as piling and dust falling during printing due to coarse particles, and inter-fiber bond strength due to fine particles ( Problems such as a decrease in internal bond strength occurred.
Therefore, as a method for increasing the opacity of paper, it has been proposed to blend a high refractive index filler such as titanium dioxide. Titanium dioxide has a particle size as small as 0.2 to 0.3 μm and has a low yield. Therefore, Patent Document 4 proposes composite particles in which titanium dioxide is combined with calcium carbonate, white carbon, or the like. Yes. Patent Document 5 proposes composite particles composed of silicon dioxide or silicate and light calcium carbonate, and containing light calcium carbonate more than silicon dioxide or silicate. Patent Document 6 proposes composite particles composed of silicon dioxide or silicate and light calcium carbonate, in which the weight ratio of silicic acid and light calcium carbonate is specified.
Further, as a method for removing coarse particles, a classification process using a vibrating screen or a method of wet pulverizing the slurry after the reaction has been proposed (see Patent Document 7).
In addition, a method of reducing the generation of fine particles of 1 μm or less while reducing the average particle size by reducing coarse particles by thoroughly pulverizing during the manufacturing process of the porous filler is disclosed ( (See Patent Document 8).
Japanese Patent Laid-Open No. 10-226974 (Japanese Patent No. 3227421) Japanese Patent Laid-Open No. 11-12993 Japanese Patent No. 3306860 (Japanese Patent Laid-Open No. 10-226982) JP 2002-29739 A (Patent No. 3392109) JP 2003-212539 A JP 2005-219945 A Japanese Patent Laid-Open No. 5-301707 Japanese Patent No. 2908253 (Japanese Patent Laid-Open No. 8-91820)

However, in the composite particles described in Patent Document 4, since titanium dioxide is more expensive than other fillers, the amount of titanium dioxide used is limited in terms of cost in printing paper with high versatility, and the opaqueness of white paper Could not be secured sufficiently. Although the composite particles described in Patent Documents 5 and 6 are fillers for the purpose of increasing the bulk of the paper, the effect of increasing the bulk of the paper is insufficient.
In the classification process, although coarse particles can be removed, waste is increased. Further, in the wet pulverization described in Patent Document 7, since fine particles are increased by the pulverization treatment, the internal bond strength cannot be ensured when the obtained porous filler is blended with paper. Moreover, the aggregated structure was destroyed by pulverization, and the bulkiness of the porous filler was reduced.
According to the method described in Patent Document 8, coarse particles can be reduced while maintaining the bulking effect, but the amount of fine particles is increased by thorough pulverization during the manufacturing process, even if not as much as wet pulverization. did. For this reason, the fiber-to-fiber bond (internal bond strength) when blended with paper was lowered, and the viscosity of the liquid containing the porous filler was increased.
The present invention has a high bulking effect when blended with paper, can increase the opacity of white paper, has an appropriate average particle size and narrow particle size distribution, and has high surface strength and internal bond strength of paper. An object of the present invention is to provide a porous filler that can be produced and a method for producing the same. Another object of the present invention is to provide a paper which is bulky and has high opacity, surface strength and internal bond strength.

The porous filler of the present invention contains silicon-containing particles formed from silicon dioxide and / or silicate, and 0.1 to 24 parts by mass of alkali-resistant microparticles with respect to 100 parts by mass of the silicon-containing particles. It is characterized by doing.
In the porous filler of this invention, it is preferable that the average particle diameter of an alkali-resistant microparticle is 0.2-10 micrometers.
In the method for producing a porous filler of the present invention, after adding alkali-resistant microparticles to an aqueous alkali silicate solution, a mineral acid solution and / or a metal salt solution of a mineral acid is added and neutralized to obtain silicon-containing particles. A method for producing a porous filler to be deposited,
The addition amount of the alkali-resistant fine particles is 0.5 to 30 parts by mass with respect to 100 parts by mass of the silicon-containing particles.
In the manufacturing method of the porous filler of this invention, it is preferable that the average particle diameter of an alkali-resistant microparticle is 0.2-10 micrometers.
In the method for producing a porous filler of the present invention, it is preferable to add a mineral acid solution and / or a metal salt solution of a mineral acid in two or more stages.
In that case, in the addition of the first stage mineral acid solution and / or the metal salt solution of the mineral acid, the temperature of the alkali silicate aqueous solution may be 20 to 60 ° C., and the second and subsequent stages may be 70 ° C. or higher. preferable.
The paper of the present invention is characterized by containing the porous filler described above.

The porous filler of the present invention has a high bulking effect when blended with paper, and can increase the opacity of white paper, and has an appropriate average particle size and narrow particle size distribution, and has a surface strength and internal strength of the paper. Bond strength can be increased.
According to the method for producing a porous filler of the present invention, the bulking effect when blended with paper is high, the opacity of white paper can be increased, and the paper has an appropriate average particle size and narrow particle size distribution, It is possible to produce a porous filler that can increase the surface strength and internal bond strength.
The paper of the present invention is bulky and has high opacity, surface strength and internal bond strength.

(Porous filler)
The porous filler of the present invention contains silicon-containing particles formed from silicon dioxide and / or silicate and alkali-resistant fine particles.
Here, the silicate forming the silicon-containing particles is a compound represented by the general formula xM ₂ O · ySiO ₂ , xMO · ySiO ₂ , xM ₂ O ₃ · ySiO ₂ , wherein M is Al, Fe , Ca, Mg, Na, K, Ti, Zn (x and y are arbitrary positive numerical values).

  Examples of the alkali-resistant fine particles include kaolin, calcined kaolin, calcium carbonate, barium sulfate, titanium dioxide, talc, alumina, magnesium carbonate, magnesium oxide, and magnesium hydroxide. Among these, calcium carbonate, kaolin, and talc are preferable because of cost advantage.

The content of the alkali-resistant fine particles is 0.1 to 24 parts by mass with respect to 100 parts by mass of the silicon-containing particles, and a preferable lower limit is 1.0 part by mass. When the content of the alkali-resistant fine particles is within the above range, a porous filler having an appropriate average particle diameter and a narrow particle size distribution can be obtained which is suitable for increasing the bulk of the paper. If the content of the alkali-resistant microparticles is less than 0.1 parts by mass, an appropriate average particle diameter and a narrow particle size distribution cannot be obtained. If the content exceeds 24 parts by mass, the effect of increasing the bulk of the paper of the porous filler is ineffective. It will be enough.
The content of the alkali-resistant fine particles is obtained by tableting a powder sample of the porous filler and then measuring the amount of oxide of each element using a fluorescent X-ray analyzer.

The average particle diameter of the alkali-resistant fine particles is preferably 0.2 to 10 μm. If the average particle size is reduced to less than 0.2 μm, the cost is increased. If the average particle size is more than 10 μm, the effect of narrowing the particle size distribution is reduced, and problems such as piling and powder falling during printing may occur.
The average particle diameter of the alkali-resistant fine particles can be adjusted by using a grinding equipment such as a sand grinder. At that time, a dispersant such as polyacrylate, polycarboxylate, hexametaphosphate, pyrophosphate can be used.

The porous filler of the present invention preferably has an average particle size of 10 to 25 μm. When the average particle size of the porous filler is less than 10 μm, the internal bond strength is greatly reduced when blended with paper, and paper dust or blisters may be generated during printing. In addition, when the average particle diameter of the porous filler exceeds 25 μm, the coarse particles increase. Therefore, when blended with paper, the smoothness of the paper is lowered, and the coarse particles present on the paper surface fall off. As a result, printing troubles such as piling may occur. In addition, the average particle diameter in the present invention is a value that is measured by a laser diffraction method using SALD2000J (manufactured by Shimadzu Corporation) and is 50% in volume integration.
The particle size distribution of the porous filler is preferably a distribution in which the difference between the particle diameter and the average particle diameter at 25% and 75% volume integrated values is within a range of ± 35% of the average particle diameter. With such a particle size distribution, both coarse particles and fine particles are reduced, and the distribution becomes narrower. Therefore, when blended in paper, better surface strength and internal bond strength can be obtained.

The porous filler of the present invention preferably has a pore volume of 2.0 to 5.0 mL / g.
If the pore volume of the porous filler is less than 2.0 mL / g, it may not be sufficiently bulky even if blended with paper. If it exceeds 5.0 mL / g, the slurry during the production of the porous filler Viscosity may increase or drying properties may decrease when blended into paper. Here, the pore volume is a value when measured by a mercury intrusion method using a pore sizer 9230 (manufactured by Shimadzu Corporation) and integrated with a pore diameter of 0.01 to 10 μm.

Moreover, it is preferable that the specific surface area of a porous filler is 50-200 m < ² > / g. If the specific surface area of the porous filler is less than 50 m ² / g, the effect of increasing the paper bulk may be insufficient, and if it exceeds 200 m ² / g, the effect of improving the opacity of the paper may be insufficient. The specific surface area is a value measured by the mercury intrusion method, and is the surface area of all pores assuming that the pore shape is a geometric cylinder, and was obtained from the relationship between the pressure in the measurement range and the amount of mercury injected. Value.

  Since the porous filler contains silicon-containing particles and a specific amount of alkali-resistant microparticles smaller than silicon-containing particles, it has an appropriate average particle size, and both coarse particles and fine particles are Has a small narrow particle size distribution. Further, when this porous filler is added to paper, the effect of increasing the bulk is high, and the opacity, surface strength and internal bond strength of the white paper can be increased.

(Method for producing porous filler)
The manufacturing method of the porous filler of this invention is demonstrated.
In the method for producing a porous filler of the present invention, after adding alkali-resistant microparticles to an alkali silicate aqueous solution, a mineral acid solution and / or a metal salt solution of a mineral acid is added to neutralize the alkali silicate aqueous solution. This is a method for precipitating silicon-containing particles.
Here, the alkali silicate aqueous solution is not particularly limited, but a sodium silicate aqueous solution or a potassium silicate aqueous solution is preferable. The concentration of the alkali silicate aqueous solution is preferably 3 to 15% because the porous filler can be produced efficiently. When the alkali silicate aqueous solution is a sodium silicate aqueous solution, the SiO ₂ / Na ₂ O mole The ratio is preferably 2.0 to 3.4.

  The addition amount of the alkali-resistant fine particles is 0.5 to 30 parts by mass, preferably 1 to 25 parts by mass with respect to 100 parts by mass of the silicon-containing particles to be generated. When the addition amount of the alkali-resistant fine particles is within the above range, a porous filler having an alkali-resistant fine particle content of 0.1 to 24 parts by mass can be easily produced. Therefore, a porous filler suitable for increasing the bulk of the paper and having an appropriate average particle diameter and narrow particle size distribution can be obtained. Although the reason for this is not clear, it is considered that the precipitation of silicon-containing particles proceeds while including alkali-resistant microparticles due to the presence of alkali-resistant microparticles when silicon-containing particles are deposited. The silicon-containing particles including alkali-resistant fine particles are considered to have a small particle size and form a narrow particle size distribution by stirring during precipitation. When the addition amount of the alkali-resistant microparticles is less than 0.5 parts by mass, it does not function sufficiently as the core of the silicon-containing particles during precipitation, and when it exceeds 24 parts by mass, the bulkiness of the silicon-containing particles is impaired.

The alkali-resistant microparticles are preferably added to the alkali silicate aqueous solution while the alkali silicate aqueous solution is stirred while the alkali-resistant microparticles are added to the aqueous solution of the alkali-resistant microparticles. An aqueous solution can be added.
In addition, the alkali-resistant fine particles may be added all at once to the alkali silicate aqueous solution before the addition of the mineral acid solution and / or the metal salt solution of the mineral acid, or may be added in multiple portions. Good.

  In the mineral acid solution and / or the metal salt solution of the mineral acid used in the present invention, examples of the mineral acid include hydrochloric acid, sulfuric acid, nitric acid and the like, and the metal salt of the mineral acid includes a sodium salt of the mineral acid, A potassium salt, a calcium salt, an aluminum salt, etc. are mentioned. Among these, sulfuric acid and aluminum sulfate are preferable from the viewpoint of cost and handling, and an aqueous solution is preferable.

  The addition amount of the mineral acid solution and / or the metal salt solution of the mineral acid is in the range of 95 to 100% of the theoretically required neutralization amount, and the amount for adjusting the pH of the resulting slurry to be in the range of more than 6.5 and 10 or less It is preferable that When the addition amount of the mineral acid solution and / or the metal salt solution of the mineral acid is less than 95% of the theoretically required neutralization amount or the pH of the resulting slurry exceeds 10, the alkaline silicate aqueous solution as the raw material There is a lot of waste. On the other hand, when the neutralization amount exceeds 100% of the theoretically necessary neutralization amount or the pH of the resulting slurry is 6.5 or less, the alkali-resistant fine particles are dissolved in the mineral acid solution and / or the metal salt solution of the mineral acid. As a result, the yield of the porous filler may decrease. In addition, when the alkali-resistant fine particles are dissolved in the mineral acid solution and / or the metal salt solution of the mineral acid, it is difficult to reuse the filtrate obtained by separating from the slurry.

At the time of precipitation of the silicon-containing particles, it is preferable to stir at a speed of 5 to 15 m / sec with a stirring device. Here, the peripheral speed is an index of the shearing force, and the shearing force increases as the peripheral speed increases. When the peripheral speed is less than 5 m / sec, the shear force is too small, and it may be difficult to obtain an appropriate average particle size and narrow particle size distribution even if alkali-resistant fine particles are included.
On the other hand, when the peripheral speed at the time of precipitation exceeds 15 m / sec, the shearing force becomes too large, the particle size of the porous filler becomes small, and the internal bond strength may be lowered when blended in paper. In addition, the load power increases and the equipment costs increase.
As the stirring device, an agitator, a homomixer, a pipeline mixer or the like is preferable. Although it is possible to use a pulverizer such as a ball mill or a sand grinder, it is not preferable because problems such as an increase in fine particles and a thickening of the slurry tend to occur.

The mineral acid solution and / or the metal salt solution of the mineral acid may be added to the alkali silicate aqueous solution all at once, but since it has a better particle size distribution, it is divided into two or more stages. It is preferable to add.
When adding a mineral acid solution and / or a metal salt solution of a mineral acid in two or more stages, since the particle size distribution is particularly good, the temperature of the first stage alkali silicate aqueous solution is set to 20 to 60 ° C., It is preferable to set it to 70 degreeC or more after the 2nd step | paragraph. In the first stage, it is preferable that the addition amount of the mineral acid solution and / or the metal salt solution of the mineral acid is in the range of 10 to 50% of the theoretically required neutralization amount.

In both the first and second stages, the mineral acid solution and / or the metal salt solution of the mineral acid can be added all at once or continuously to the alkali silicate aqueous solution.
After completion of the addition of the mineral acid solution and / or the metal salt solution of the mineral acid, an aging step of stirring while maintaining the temperature at the time of addition may be included as necessary.

  When adding the mineral acid solution and / or the metal salt solution of the mineral acid in one stage, the temperature of the alkali silicate aqueous solution is preferably 60 ° C. to the boiling point of the solution, and 75 ° C. to the boiling point of the solution. More preferably. The mineral acid solution and / or the metal salt solution of the mineral acid can be added to the alkali silicate aqueous solution all at once or continuously.

  In the production method of the present invention, an electrolyte substance such as sodium sulfate may be appropriately added in order to maintain and stabilize the viscosity of the obtained porous filler slurry.

  In the method for producing a porous filler according to the present invention in which a mineral acid solution and / or a metal salt solution of a mineral acid is added to a sodium silicate aqueous solution as described above after adding a specific amount of alkali-resistant fine particles, Silicon-containing particles can be deposited while including alkaline microparticles. The porous filler obtained in this way has an appropriate average particle size, and has a narrow particle size distribution in which both coarse particles and fine particles are small, so that the surface strength and internal bond strength of paper can be increased. . Further, when such a porous filler is added to paper, the effect of increasing the bulk is high and the opacity of the white paper can be increased.

(paper)
The paper of the present invention contains the above porous filler. In addition to the above porous filler, various pigments generally used for paper as required, such as kaolin, calcined kaolin, calcium carbonate, calcium sulfate, barium sulfate, titanium dioxide, talc, zinc oxide, alumina , Magnesium carbonate, magnesium oxide, amorphous silicate, bentonite, zeolite, sericite, smectite and other mineral pigments, styrene resins, urea resins, melamine resins, acrylic resins, vinylidene chloride resins and their fine particles Organic pigments such as hollow particles may be included.

Examples of cellulose fiber raw materials for forming paper include chemical pulps such as kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP), semi-chemical pulp (SCP), and chemiground wood pulp (CGP). Semi-chemical pulp, ground pulp (GP), thermo-mechanical pulp (TMP, BCTMP) and other mechanical pulp, non-wood pulp made from cocoon, coconut, hemp, kenaf, etc., deinked pulp made from waste paper Is mentioned.
These may be used alone or in combination of two or more.

The paper of the present invention is obtained by preparing a stock containing a cellulose fiber raw material and the above porous filler, and papermaking the stock. Examples of the paper machine used at that time include a long net type, a circular net type, a short net type, and a twin wire type paper machine.
In the paper stock, various anionic, nonionic, cationic or amphoteric yield improvers, drainage improvers, paper strength enhancers, internal sizing agents, etc. Auxiliary additives for paper making such as auxiliary agents, dyes, fluorescent brighteners, pH adjusters, antifoaming agents, pitch control agents, slime control agents and the like can be appropriately added.

  The paper of the present invention includes various surface binders such as starch, polyvinyl alcohol, and polyacrylamide, surface sizing agents such as rosin sizing agents, synthetic sizing agents, petroleum resin sizing agents, neutral sizing agents, sodium chloride, A conductive agent such as sodium sulfate may be applied or impregnated.

  Since the paper of the present invention described above contains the above porous filler, it is bulky and has high opacity, surface strength and internal bond strength. Such paper is suitably used for printing paper and high-quality coated paper.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “parts” and “%” mean “parts by mass” and “% by mass” unless otherwise specified.

Synthesis example 1
After diluting 330 g of commercially available No. 3 sodium silicate aqueous solution (solid content concentration 38%) with 900 g of tap water, 160 g of 5% aqueous sodium sulfate solution was added. Further, as alkali-resistant microparticles, a calcium carbonate dispersion A (TP-121, manufactured by Okutama Kogyo Co., Ltd., solid content concentration of 9.5%, adjusted to have an average particle size of 0.6 μm with a sand grinder, in the table) Is expressed as “charcoal A”.) 100 g (10 parts with respect to 100 parts of silicon-containing particles) is stirred with a three-one motor (pitched turbine blades, referred to as “stirrer A” in the table) while stirring. Added at 50 ° C. Thereafter, the peripheral speed of the stirring blade was adjusted to 10 m / second, 75 g of sulfuric acid (concentration 20%) was added in 15 minutes to neutralize the first stage, and then the temperature was increased to 90 ° C. at the above peripheral speed. Warm up. Subsequently, 168 g of sulfuric acid was added over 40 minutes at the same temperature, and the second stage neutralization was performed to obtain a porous filler. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8.
When the obtained porous filler was measured with the laser diffraction particle size distribution analyzer, the particle diameters of the 25%, 50%, and 75% mass integrated values were 12.6, 17.0, and 21.5 μm, respectively. .
The filler slurry was filtered and washed, then redispersed in water, and used for handsheet evaluation. In addition, a part of the cake after filtration and washing was dried at 105 ° C. and subjected to measurement of pore volume, specific surface area, and measurement of alkali-resistant fine particle content using a fluorescent X-ray analyzer. The content of alkali-resistant fine particles in the porous filler obtained in Synthesis Example 1 was 9 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 2 After diluting 330 g of commercially available No. 3 sodium silicate aqueous solution (solid content concentration 38%) with 820 g of tap water, 240 g of 5% aqueous sodium sulfate solution was added. Further, 15 g of calcium carbonate dispersion A (1.5 parts with respect to 100 parts of silicon-containing particles) was added as alkali-resistant fine particles at a temperature of 50 ° C. while stirring with a stirrer A. Thereafter, the peripheral speed of the stirring blade was adjusted to 12 m / second, 60 g of sulfuric acid (concentration 20%) was added in 15 minutes to neutralize the first stage, and then the temperature was increased to 90 ° C. at the above peripheral speed. Warm up. Subsequently, 183 g of sulfuric acid was added over 40 minutes at the same temperature, and the second stage neutralization was performed to obtain a porous filler. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 7.5.
The particle diameters of 25%, 50% and 75% mass integrated values of the obtained porous filler measured with a laser diffraction particle size meter were 10.5, 14.8 and 19.7 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 1.2 parts with respect to 100 parts of silicon-containing particles.

Synthesis example 3
In Synthesis Example 1, a porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount of tap water was changed to 800 g and the amount of calcium carbonate dispersion A was changed to 200 g (20 parts relative to 100 parts of silicon-containing particles). . The total addition amount of sulfuric acid was 98% of the theoretical neutralization amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8.5. Moreover, the particle diameters of 25%, 50% and 75% mass integrated values of the obtained porous filler measured by a laser diffraction particle size meter were 11.4, 14.3 and 18.0 μm, respectively. The content of alkali-resistant microparticles in the porous filler was 17 parts with respect to 100 parts of silicon-containing particles.

Synthesis example 4
In Synthesis Example 1, the amount of tap water was 750 g, the calcium carbonate dispersion A was a calcium carbonate dispersion B adjusted to have an average particle diameter of 2 μm as alkali-resistant microparticles (solid content concentration 9.5%, in the table “ It is expressed as “Carbon Cal B”.) A porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount was changed to 150 g (15 parts relative to 100 parts of silicon-containing particles). The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of the 25%, 50% and 75% mass integrated values of the obtained porous filler measured by a laser diffraction particle size meter were 14.0, 19.0 and 24.3 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 13 parts with respect to 100 parts of silicon-containing particles.

Synthesis example 5
In Synthesis Example 1, 100 g of alkali-resistant fine particles were dispersed in calcium carbonate having an average particle diameter of 4 μm (Callite SA, manufactured by Shiroishi Kogyo Co., Ltd., solid content concentration: 9.5%, “charcoal cal C” in the table). A porous filler was obtained in the same manner as in Synthesis Example 1 except that it was changed to (10 parts with respect to 100 parts of silicon-containing particles). The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50% and 75% mass integrated values of the obtained porous filler measured by a laser diffraction particle size meter were 13.4, 19.6 and 25.8 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 6
In Synthesis Example 1, 100 g of a calcium carbonate dispersion A (UW90, manufactured by Engelhard, solid content concentration of 9.5%) with an average particle diameter adjusted to 0.6 μm (based on 100 parts of silicon-containing particles) Except for changing to 10 parts), a porous filler was obtained in the same manner as in Synthesis Example 1. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 7. Moreover, the particle diameters of the 25%, 50%, and 75% mass integrated values measured with a laser diffraction particle size meter of the obtained porous filler were 12.5, 15.9, and 20.1 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9.5 parts with respect to 100 parts of silicon-containing particles.

Synthesis example 7
In Synthesis Example 1, 840 g of tap water and alkali-resistant fine particles were dispersed in calcium carbonate (Brilliant 15, manufactured by Shiroishi Kogyo Co., Ltd., average particle size 0.7 μm, solid content concentration 9.5%. The porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount was changed to 60 g (6 parts with respect to 100 parts of silicon-containing particles). The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50% and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 15.1, 22.7 and 30.1 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 5.1 parts with respect to 100 parts of silicon-containing particles.

Synthesis example 8
After diluting 330 g of commercially available No. 3 sodium silicate aqueous solution with 820 g of tap water, 240 g of 5% aqueous sodium sulfate solution was added. Further, 100 g of calcium carbonate dispersion A (10 parts with respect to 100 parts of silicon-containing particles) was added as alkali-resistant microparticles at a temperature of 50 ° C. while stirring with a homomixer (shown as “stirrer B” in the table). Thereafter, the peripheral speed of the stirring blade was adjusted to 10 m / second, and 60 g of sulfuric acid (concentration 20%) was added over 15 minutes. After the addition of sulfuric acid, the temperature was raised to 90 ° C. at the above peripheral speed. Next, 183 g of sulfuric acid was added over 40 minutes at the same temperature to obtain a porous filler. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50% and 75% mass integrated values of the obtained porous filler measured by a laser diffraction particle size meter were 13.0, 17.3 and 22.5 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 9
In Synthesis Example 1, a porous filler was obtained in the same manner as in Synthesis Example 1 except that the peripheral speed of the stirring blade was adjusted to 14 m / sec with the stirrer B and sulfuric acid was added. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 8.7, 11.4, and 14.8 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9.5 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 10
After diluting 330 g of commercially available sodium silicate No. 3 (solid content concentration 38%) with 820 g of tap water, 240 g of 5% aqueous sodium sulfate solution was added. Furthermore, after adding 100 g of calcium carbonate dispersion A (10 parts with respect to 100 parts of silicon-containing particles) at 50 ° C. while stirring with a stirrer A as alkali-resistant fine particles, the peripheral speed of the stirring blade was set to 6 m / second. After adjustment, 60 g of sulfuric acid (concentration 20%) was added over 15 minutes. After the addition of sulfuric acid, the temperature was raised to 90 ° C. at the above peripheral speed. Next, 183 g of sulfuric acid was added over 40 minutes at the same temperature to obtain a porous filler. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 19.0, 27.8, and 36.0 μm, respectively. The content of alkali-resistant microparticles in the porous filler was 8 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 11
In Synthesis Example 1, in the same manner as in Synthesis Example 1 except that 86 g of sulfuric acid was added after adding 86 g of an aqueous aluminum sulfate solution (concentration 20%) instead of sulfuric acid added after the temperature was raised to 90 ° C. I got a filler. The total addition amount of sulfuric acid and sulfate was 98% of the theoretical neutralization amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated values of the obtained porous filler measured by a laser diffraction particle size meter were 13.0, 18.0, and 23.5 μm, respectively. The content of alkali-resistant microparticles in the porous filler was 8 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 12
After diluting 330 g of commercially available No. 3 sodium silicate aqueous solution with 740 g of tap water, 320 g of 5% aqueous sodium sulfate solution was added. Without adding the alkali-resistant fine particles, the peripheral speed of the stirring blade was adjusted to 10 m / sec while stirring with a three-one motor, and 87 g of sulfuric acid (concentration 20%) was added at a temperature of 50 ° C. over 15 minutes. After the addition of sulfuric acid, the temperature was raised to 90 ° C. at the above peripheral speed.
Subsequently, 156 g of sulfuric acid was added over 40 minutes at this temperature to obtain a porous filler. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 7.5. Moreover, the particle diameters of the 25%, 50%, and 75% mass integrated values measured with a laser diffraction particle size meter of the obtained porous filler were 11.5, 22.0, and 32.8 μm, respectively.

Synthesis Example 13
A porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount of the calcium carbonate dispersion liquid A was changed to 0.6 g (0.06 parts with respect to 100 parts of silicon-containing particles) in Synthesis Example 1. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 7.5. Moreover, the particle diameters of the 25%, 50%, and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 14.9, 24.6, and 34.6 μm, respectively. The content of alkali-resistant microparticles in the porous filler was 0.05 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 14
A porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount of tap water was changed to 400 g and the amount of the calcium carbonate dispersion liquid A was changed to 600 g (60 parts relative to 100 parts of silicon-containing particles). The total sulfuric acid addition amount was 98% of the theoretical neutralization amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 9. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated value of the obtained porous filler measured by a laser diffraction particle size meter were 6.1, 8.8, and 11.8 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 55 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 15
In Synthesis Example 1, 100 g of calcium carbonate dispersion A (dispersion of calcium carbonate E) (average particle diameter 11 μm, solid content concentration 9.5%, indicated as “charcoal cal E” in the table) 100 A porous filler was obtained in the same manner as in Synthesis Example 1 except that the amount was changed to 10 parts). The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of the 25%, 50%, and 75% mass integrated values measured with a laser diffraction particle size meter of the obtained porous filler were 15.6, 26.6, and 37.8 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 16
In Synthesis Example 6, a porous filler was obtained in the same manner as in Synthesis Example 1 except that the peripheral speed of the stirring blade was adjusted to 20 m / sec with the stirrer B and sulfuric acid was added. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 5.3, 7.6, and 9.8 μm, respectively. The content of alkali-resistant fine particles in the porous filler was 9.5 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 17
In Synthesis Example 1, the amount of tap water is 950 g, the amount of the calcium carbonate dispersion A is 5.0 g (0.5 part with respect to 100 parts of silicon-containing particles), and the peripheral speed of the stirring blade of the stirrer A is 4 m / second. A porous filler was obtained in the same manner as in Synthesis Example 1 except that sulfuric acid was added after adjustment. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of 25%, 50%, and 75% mass integrated values measured with a laser diffraction particle size meter of the obtained porous filler were 18.8, 37.8, and 55.4 μm, respectively. The content of alkali-resistant microparticles in the porous filler was 0.4 parts with respect to 100 parts of silicon-containing particles.

Synthesis Example 18
In Synthesis Example 1, a porous filler was obtained in the same manner as in Synthesis Example 1, except that 113 g of sulfuric acid added at 50 ° C. and 131 g of sulfuric acid added after raising the temperature to 90 ° C. were changed to 131 g. The total amount of sulfuric acid added was 98% of the theoretical neutralized amount of sodium silicate, and the pH of the reaction solution after addition of sulfuric acid was 8. Moreover, the particle diameters of the 25%, 50%, and 75% mass integrated values measured by a laser diffraction particle size meter of the obtained porous filler were 21.6, 35.3, and 53.0 μm, respectively.
The content of alkali-resistant fine particles in the porous filler was 9.7 parts with respect to 100 parts of silicon-containing particles.

  The conditions of the synthesis examples 1 to 18 are summarized in Tables 1 and 2.

Production Example 1
To the bleached chemical pulp (BKP) slurry having a Canadian standard freeness (CSF) of 450 mL, the porous filler obtained in Synthesis Example 1 is added to 8 parts per mass of paper, and further per 100 parts of absolute dry pulp quantity. 1.0 parts of starch, 0.03 parts of alkyl ketene dimer, and 0.5 parts of sulfuric acid band and 0.02 parts of yield improver (DR-1500, manufactured by Hymo Co., Ltd.) Was prepared. The stock was made using a square handmaking device so that the target basis weight was 70 g / m ² when air-dried, dehydrated by a press, and then dried using a cylinder dryer to produce a sheet. Thereafter, a calendering treatment was performed at a linear pressure of 10 kg / cm to obtain a synthetic paper.

Production Examples 2-18
Except that the porous filler obtained in Synthesis Example 1 in Production Example 1 was changed to those obtained in Synthesis Examples 2 to 18 as shown in Table 1 or Table 2, respectively, under the same conditions as in Production Example 1. An adult paper was obtained.

The paper of each production example was evaluated as follows. The evaluation results are shown in Table 3 or Table 4.
-Paper density: Measured according to JIS P 8118.
Ash content: Ashed at 525 ° C. based on JIS P 8251.
Opacity: Measured according to JIS P 8149.
Smoothness: TAPPI No. 5 Measured with Oken type smoothness tester.
-Internal bond strength: TAPPI No. It measured according to 18-2.
Printing strength: Measured using an offset ink T13 with an RI printing machine (Made Seisakusho), and the result was evaluated and displayed.
A: High in strength, practically satisfactory, and excellent in quality.
○: Strength is high and there is no practical problem.
Δ: The strength is slightly inferior, and there is a problem in practical use.
X: Strength is remarkably inferior, it is a problem in practical use, and quality is remarkably inferior.

The porous fillers of Production Examples 1 to 11 containing silicon-containing particles and a specific amount of alkali-resistant microparticles and produced by a specific production method have a high bulking effect when blended with paper, and are white paper. The opacity of can be increased. Moreover, it had an appropriate average particle diameter and narrow particle size distribution, and was able to increase the surface strength and internal bond strength of paper.
On the other hand, the porous filler of Production Example 12 containing no alkali-resistant microparticles did not give satisfactory results in the white paper opacity, internal bond strength, and surface strength.
The porous filler of Production Example 13 in which the alkali-resistant fine particles were less than 0.1 parts by mass had insufficient internal bond strength and surface strength.
The porous filler of Production Example 14 in which the content of the alkali-resistant fine particles exceeded 24 parts by mass did not provide a satisfactory bulking effect.
The porous filler of Production Example 15 in which the particle diameter of the alkali-resistant microparticles exceeded 10 μm tended to be unable to increase the smoothness.
The porous filler of Production Example 16 in which the peripheral speed of stirring at the time of precipitation was 20 m / second and the average particle diameter was less than 10 μm was insufficient in bulking effect, and had an internal bond strength and surface strength of paper. There was a tendency to decrease.
The porous filler of Production Example 17 in which the peripheral speed of stirring during precipitation was 4 m / sec and the average particle diameter exceeded 25 μm decreased the opacity of the white paper, the surface strength of the paper, and the smoothness was insufficient. There was a trend.
The porous filler of Production Example 18 in which the pore surface area of the porous filler exceeds 200 m ² / g, the particle diameter is larger than 30 μm, and the particle size distribution is wide decreases the opacity of the white paper and the surface strength of the paper. There was a trend. Further, the smoothness of the paper also tended to decrease.

Claims (7)

  A porous material comprising silicon-containing particles formed from silicon dioxide and / or silicate, and 0.1 to 24 parts by mass of alkali-resistant microparticles with respect to 100 parts by mass of the silicon-containing particles. Filler.   The porous filler according to claim 1, wherein the average particle diameter of the alkali-resistant fine particles is 0.2 to 10 µm. A method for producing a porous filler in which after adding alkali-resistant microparticles in an aqueous alkali silicate solution, a mineral acid solution and / or a metal salt solution of a mineral acid is added and neutralized to precipitate silicon-containing particles. ,
The method for producing a porous filler, wherein the addition amount of the alkali-resistant fine particles is 0.5 to 30 parts by mass with respect to 100 parts by mass of the silicon-containing particles.   The method for producing a porous filler according to claim 3, wherein the average particle diameter of the alkali-resistant fine particles is 0.2 to 10 µm.   The method for producing a porous filler according to claim 3 or 4, wherein the mineral acid solution and / or the metal salt solution of the mineral acid is added in two or more stages.   The porosity according to claim 5, wherein in the addition of the first stage mineral acid solution and / or the metal salt solution of the mineral acid, the temperature of the alkali silicate aqueous solution is 20 to 60 ° C, and the second and subsequent stages are set to 70 ° C or higher. A method for producing sex fillers.   A paper comprising the porous filler according to claim 1 or 2.