JP3872090B1 - Inorganic particle aggregate - Google Patents

Abstract

A using wastes such as paper sludge as a raw material, was not obtained by the conventional reproduction inorganic particles, the yield resistance during paper making, bulkiness, surface flatness, printing aptitude, inorganic having excellent oil-absorbing Particle aggregates are provided.
An inorganic particle agglomerate obtained by firing a waste, containing calcium, silica and aluminum in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxides, And the total content rate of the said calcium, the said silica, and the said aluminum is 90 mass% or more.
[Selection figure] None

Description

  The present invention relates to wastewater sludge containing fillers and pigments discharged in the wastewater treatment process of a paper mill, papermaking sludge discharged in the wastepaper dissolution process and foreign matter removal process in the wastepaper treatment process, and dewatering discharged in the wastepaper deinking process. Can be used as a papermaking sludge such as black floss, papermaking sludge discharged in the raw material adjustment process, etc., and can be used as a filler or pigment for papermaking, or as a filler, heat insulating material, soundproofing material, etc. Relates to an aggregate of inorganic particles derived from paper sludge.

  Inorganic particles are used as spreaders and extenders for agricultural chemicals, extenders for paints and printing inks, reinforcing agents for rubbers, fillers and modifiers for plastics (molded articles, films, fibers, etc.) . Here, the usage form in the paper industry where the amount of white pigment used is the largest is described as a representative example.

  In the papermaking technical field, in order to improve paper whiteness, opacity, paper surface flatness, halftone dot reproducibility during printing, etc. For the purpose of countermeasures for opacity and back-through, to improve the drying speed of wet paper in papermaking and to reduce the drying energy cost, to reduce the raw material cost by the effect of the bulking material, or to improve various characteristics of the paper surface Therefore, it is used as a pigment for a coating layer provided on a base paper mainly composed of pulp.

  Examples of such papermaking fillers and pigments include clay (hydrous aluminum silicate), calcium carbonate, zinc oxide, aluminum hydroxide, zinc sulfide, titanium dioxide, calcium sulfate, calcium sulfite, barium sulfate, talc, and silica. It is known and used alone or in combination.

  Hereinafter, the “filler” described in the present specification refers to a so-called internal filler that is added in the raw material adjustment step during papermaking in papermaking. In addition, the “pigment” described in the present specification refers to a pigment added to a coating composition at the time of producing coated paper.

  In the papermaking process, the main ingredients are fiber content such as pulp as a raw material for papermaking, organic substances such as starch and synthetic adhesives, and the fillers and pigments for papermaking that are contained in wastewater without being produced in paper products. In addition, a so-called paper sludge is generated, which is composed of inorganic substances that are washed out, lignin washed out in the pulping process, papermaking pigments derived from waste paper, printing ink attached thereto, surplus sludge generated in the biological wastewater treatment process, and the like. In recent years, as the waste paper utilization rate increases, paper sludge derived from the waste paper deinking process continues to increase.

  These paper sludges are collected, and the organic sludge in the paper sludge is burned in an incinerator such as a fluidized bed furnace or a stalker furnace to reduce the volume of the paper sludge and is recovered as energy. However, since papermaking sludge contains a large amount of inorganic substances, a large amount of combustion ash (inorganic substances) remains even after combustion, and there is a limit to volume reduction. Therefore, efforts have been made to utilize the combustion ash as a raw material for cement and as a soil conditioner. However, these are methods that use incinerated ash as an auxiliary material for cement raw materials and soil conditioners, and the amount of use is very small. After all, most of the combustion ash is landfilled. is there.

  For this reason, the reuse of not only organic materials recovered as energy by incineration but also inorganic materials remaining as incineration ash as fillers and pigments for papermaking is an important improvement related to environmental issues in the papermaking industry as well as to improve the wastepaper utilization rate. It is a problem. However, the incineration ash of simple papermaking sludge contains organic substances that remain without being burned as carbon, so the whiteness is low, or the sintering of inorganic substances progresses, and the particle size is uneven and large, As it is, it is not suitable for use as a paper filler or a coating pigment. Therefore, Patent Document 1 discloses a method of using combustion ash (incineration ash) after reburning and improving the whiteness.

  However, in the method of reburning incinerated ash, when the reburning temperature is set to 500 to 900 ° C., the whiteness of the incinerated ash is improved only to about 50%, and it is used as a paper filler or coating pigment. It has been found that it is not suitable to do. It has also been found that when the reburning temperature is set to over 900 ° C., the burning ash (inorganic material) is sintered and melted and becomes extremely hard. Also, when reburned ash is used as a filler, this reburned ash has very hard properties, so the papermaking wire wears out quickly and the life of the papermaking wire becomes very short, so it can be used in actual operations. It wasn't. Further, when the reburned ash is used as a coating pigment, the reburned ash has a very hard property, so that there arises a problem that the smoothness of the surface of the coating layer is inferior even when the calendar treatment is performed.

  In this regard, it is conceivable to grind the reburned ash and reduce its particle size to reduce wear and improve smoothness, but when used as an internal filler, the yield during paper making is low. Or because the combustion ash itself is extremely hard, the energy cost for pulverization becomes extremely high.

  In addition, as in Patent Document 2, sludge is supplied into a reactor into which an oxygen-containing gas has been injected, and oxidized at 250 to 300 ° C. under a heating and pressurization of about 3000 psig for 0.25 to 5 hours. A method for regenerating the inorganic material as a pigment for papermaking has been proposed.

  However, since this method is based on wet air oxidation treatment of sludge, organic matter removal is not sufficient, the whiteness of the obtained pigment is low, the particle size is not uniform, and the reaction operation is complicated and costly. There is a problem that is high.

  On the other hand, Patent Document 3 proposes a method in which after making papermaking sludge into PS charcoal, it is further incinerated with a kiln to produce white clay as a papermaking raw material. However, this method has a great demerit that not only energy cannot be effectively extracted from the papermaking sludge but also input energy is required because the papermaking sludge is fried. Further, the generated white clay also has a large particle size and has a problem that it cannot be used as a papermaking pigment.

That is, when inorganic particles obtained by a conventionally known method are internally added in the papermaking process, the yield stability cannot be obtained, and the dispersion state when adjusting the coating paper pigment may become unstable. In many cases, the surface quality of the coating layer is unstable with respect to the quality such that smoothness cannot be obtained at a predetermined paper thickness and the clarity of the image line is lowered.
JP-A-11-310732 Japanese Examined Patent Publication No. 56-27638 Japanese Patent Laid-Open No. 54-14367

  As a result of intensive studies to solve these problems, the present inventors have found that the composition can be solved by the component constitution forming inorganic particles and the ratio of these components to the whole particle. Therefore, the main problem to be solved by the present invention is to use waste such as papermaking sludge as a raw material, which was not obtained with conventional recycled inorganic particles, yield at the time of papermaking, bulkiness, surface flatness, An object of the present invention is to provide an inorganic particle aggregate excellent in printability and oil absorption.

The present invention that has solved this problem is as follows.
[Invention of Claim 1]
An inorganic particle aggregate that can be used as a filler or pigment for papermaking,
Using the deinking floss discharged in the wastepaper deinking process as the main raw material,
Dehydration and drying, baking, resulting et been pulverized to an inorganic particle aggregates was adjusted to the following composition without adding a step for aggregating the particles after grinding step,
Oil absorption according to JIS K 5101 method is 30 to 100 ml / 100 g.
An inorganic particle aggregate characterized by that.
(composition)
The inorganic particle aggregate contains calcium, silicon, and aluminum as constituents of the inorganic particle aggregate in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxide, and the inorganic particle The inorganic particle aggregate whose total content rate of the said calcium, the said silicon, and the said aluminum is 90 mass% or more in an inorganic particle aggregate structural component among the particle structural components of an aggregate.

(Function and effect)
The inorganic particle agglomerates of the present invention are obtained by calcining what is the main raw material for deinking floss, that is, since deinking floss is used as a raw material, there is no problem of increased waste. In addition, the manufacturing cost is reduced because the raw material is inexpensive.
When the inorganic particle aggregate of the present invention is added as a pigment to a coating solution, it has good compatibility with a binder and a dispersant and excellent dispersion characteristics at a high concentration, so that the strength of the coating layer is improved.
The inorganic particle aggregate of the present invention has a high oil absorbency because it contains many voids, and when it is added as a pigment to the coating liquid, the ink setting property is improved and the printability is improved.
-In the inorganic particle aggregate of the present invention, calcium is 30% by mass or more in terms of oxide, so that the whiteness of the internally added paper is increased.
・ Calcium carbonate has homogeneities such as hexagonal calcite crystal (calcite) and orthorhombic aragonite crystal (aragonite), and most limestone produced in nature is calcite. Shellfish include aragonite crystals in addition to calcite crystals. Calcium carbonate has a vaterite system that does not exist in nature. Calcium obtained from the deinking floss is various, but it becomes an almost uniform calcium carbonate property by calcination and aggregation. Therefore, inorganic fine particles that contribute to the quality stability of the inorganic fine particles themselves and have almost stable properties while being aggregates composed of different components can be obtained.
The inorganic particle aggregate of the present invention contains silicon, and since the primary particles of silicon are fine, the optical refractive index is high. Therefore, the paper in which the inorganic particle aggregate of the present invention in which silicon is converted to an oxide in an amount of 9% by mass or more is internally added as a filler has high opacity.
In addition, when the primary particles of silicon are fine, the affinity with a water-soluble adhesive such as a binder or a water-soluble auxiliary agent is increased. Therefore, when the inorganic particle aggregate of the present invention in which silicon is converted to oxide in an amount of 9% by mass or more is included in the coating liquid as a pigment, the absorbability and drying property of the printing ink are improved.
On the other hand, since the inorganic particle aggregate of the present invention has a silicon content of 35% by mass or less in terms of oxide, even when used as a pigment, it has fluidity, solid content concentration stability, that is, dispersibility. high. This is presumably because the formation of inorganic particle aggregates limits the high water absorption capability of silicon .
-The inorganic particle aggregate of this invention contains aluminum 9 mass% or more in conversion of an oxide. The main sources of aluminum are aluminum in clay, trivalent aluminum sulfate added as an auxiliary in the papermaking process, 18 hydrate, and aluminum contained in talc as impurities. Compared with the conventional inorganic filler which shows the extremely high cationic property which aluminum originally has, and anionic property, the bond strength with an anionic pulp fiber improves, and a yield and chemical fixability improve.
On the other hand, since the inorganic particle aggregate of the present invention has an aluminum content of 35% or less in terms of oxide, it does not cause paint shock due to excessive cationicity, and is not generated in the pulp suspension (pulp slurry). Middle) and a stable dispersibility in the coating liquid.
-Oil absorption by JIS K 5101 method is 30-100 ml / 100g. According to the present invention, calcium, silicon and aluminum are contained in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxide, and the total content of the calcium, silicon and aluminum is 90 When the oil absorption is less than 30 ml / 100 g in the inorganic particle aggregate having a mass% or more, the ink absorption effect is small and the back layer removal prevention effect is low. If it is 100 ml / 100 g or more, the blur of the image area and the print quality will be sunk, resulting in poor print gloss.

[Invention of Claim 2]
The inorganic particle aggregate according to claim 1, wherein an average particle size by a Coulter counter method is 0.1 to 10 µm.

(Function and effect)
-The average particle diameter of the inorganic particle aggregate of this invention by a Coulter counter method is 0.1-10 micrometers. The reason why the average particle size is in the range of 0.1 to 10 μm is that when used for papermaking pigment for internal use or papermaking pigment for coating, its dispersibility, abrasion, whiteness, brightness and opacity This is because this range is determined to be optimum in consideration of the influence on the environment.
Since the inorganic particle aggregate of the present invention is an aggregate having an average particle diameter of 0.1 μm or more, the yield is good in high-speed papermaking exceeding 1300 m / min in recent years. It has the advantage of being excellent. On the other hand, since the average particle diameter of the inorganic particle aggregate of the present invention is 10 μm or less, it has the advantages of reducing the problem of streak generation in high-speed coating and reducing the occurrence of paper dust and powder falling off.
Further, when the inorganic particle aggregate is used as a pigment for coated paper, the average particle size is 0.1 μm or less, and when the coating liquid is prepared, the dispersion liquid is dispersed when dispersed in water or an aqueous binder solution. The viscosity increases and it becomes difficult to sufficiently increase the filler concentration of the coating solution. Further, the writing property and surface strength of the ink jet recording paper are also lowered.
On the other hand, when the average particle size is larger than 10 μm, irregularities derived from the amorphous silica powder are generated on the surface of the coating layer, the feel of the paper surface is deteriorated, and the roundness of the ink dots is also lowered.
A particularly preferable average particle size of the inorganic particle aggregate is 4 to 9 μm.
The inorganic particle aggregate is slurried by adding a dispersant, and then finely divided to an average particle size of 0.1 to 10 μm by wet dispersion using a disperser. Depending on the application of the white pigment, for example, for coating It is preferable that the papermaking pigment is 0.3 to 5 μm, and the papermaking pigment for internal addition is 0.5 to 10 μm.
-Furthermore, calcium, silicon, and aluminum are contained in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxides, and the total content ratio of the calcium, the silicon, and the aluminum is 90 masses. %, The specific gravity is light and excessive aqueous solution absorption is suppressed, so that the dispersibility in the pulp suspension (pulp slurry) and coating liquid is high. Therefore, it is easy to form a bulky coating layer and paper layer, and it is easy to yield on the paper layer .

[Invention of Claim 3]
The inorganic particle aggregate according to claim 1 or 2, wherein a peak height of an average particle diameter in a differential curve of particle size distribution by a Coulter counter method is 30% or more.

(Function and effect)
-The average particle size peak height in the differential curve of the particle size distribution by the Coulter counter method is 30% or more. In the present invention, as the particle size distribution of the inorganic particle aggregate, the peak height in the differential curve is preferably 30% or more, preferably 35% or more, and the half width is preferably 5 μm or less. A peak height in such a differential curve of 30% or more and preferably a half width of 5 μm or less means that the particle size distribution is narrow (sharp). Inorganic particles with a narrow particle size distribution are more suitable for obtaining clarity of image areas and high-definition images. On the other hand, when the peak height and the half width are out of the above ranges (the particle size distribution is broad), the fineness is lost and the image becomes unclear.
-In such a differential curve, it is most preferable that one peak exists, but one or more peaks may exist if the peak is 5% or less. However, when two or more peaks are present, a portion lacking in detail is mixed, and the image is unclear compared to the case of one peak.

  According to the present invention, it has become possible to provide an inorganic particle aggregate excellent in yield, bulkiness, surface flatness, printability, and oil absorption during papermaking, which was not obtained with conventional regenerated inorganic particles. Fillers and pigments used as pigments for coating compositions such as art paper and coated paper, or for information paper such as PPC paper, thermal paper, pressure sensitive paper, thermal transfer paper, ink jet paper, electrostatic recording paper, magnetic recording paper, etc. As a filler used for non-coated paper such as high-grade and intermediate printing paper, or as filler or pigment used for rice paper, industrial hybrid paper, etc., it can be used over a wide range.

Next, an embodiment of the present invention will be described mainly with respect to a paper filler and a manufacturing method for pigments that can suitably use the inorganic particle aggregate according to the present invention. The following embodiment shows a preferred embodiment for producing an inorganic particle aggregate based on the present invention, and is not limited to this embodiment.
[Use]
The inorganic particle aggregate for papermaking of this form can be used as a filler or pigment for papermaking.

[Inorganic particle aggregates]
The inorganic particle aggregate of the present embodiment is obtained by firing what is mainly made of deinked floss.

〔waste〕
Examples of waste from the paper mill include waste sludge containing fillers and pigments discharged in the waste water treatment process of the paper mill, paper sludge discharged in the waste paper dissolution process and foreign matter removal process in the waste paper treatment process, and waste paper removal. Examples include papermaking sludge such as deinking floss discharged in the blacking process, or papermaking sludge discharged in the raw material adjustment process.
Of these, the present invention mainly uses deinking floss. Paper sludges other than deinking floss are likely to cause fluctuations in product properties because their constituent components tend to fluctuate. On the other hand, since deinking floss has almost no change in constituent components, it is easy to control the quality such as whiteness of the resulting inorganic particle aggregate, and is suitable for papermaking. The components of the deinking floss are stable with almost no change because the stability of the properties of the used paper pulp leads to stable quality of the recycled paper, because the used paper used as the raw material of the used paper pulp is almost the same quality. by.
In addition to the use of the deinking floss, it can be adjusted by mixing a certain amount of sludge with a stable property, such as coating process sludge and papermaking process sludge. become.
Here, the deinking floss is a residue after deinking and taking out the pulp in the used paper processing step. It mainly contains inorganic particles such as kaolin, calcium carbonate, talc and titanium dioxide, residual ink particles, fibers, organic compounds such as coating agents, and water.
The deinking floss is, for example, solid-liquid separated by a method such as precipitation or pressurized flotation, collected solids, dried to a predetermined moisture, and adjusted to a predetermined unburned rate in the first firing step And fired. Thereby, it becomes the porous raw material aggregated in the lump shape.

Hereinafter, taking deinking floss as an example, an example of a method for producing fine inorganic particle aggregates according to the present invention will be described in detail.
[Flocking and dehydration]
Usually, the deinking floss has a moisture content of about 95 to 98% by mass, and a floc is formed by adding a flocculant to perform dehydration. The dehydration process can be performed in one or more stages, but if the floc is solidified, it causes firing unevenness in the second firing step, which is a subsequent process. It is preferred to dehydrate to the extent.

[Drying / Classification]
The dehydrated product is dried in advance. As the drying means, known drying means such as hot air drying can be used, but it is possible to loosen the deinked floss while drying, and hot air drying means that can also perform specific gravity classification can be most preferably used.
Specific examples of the hot air drying means that can be suitably used include hot air drying by blowing hot air with hot air blowing means provided below the impeller equipment while loosening the dehydrated paper floss with an unwinding equipment such as an impeller. Drying and classification can be performed by discharging the papermaking floss having a low specific gravity out of the loosened and dried papermaking floss from a take-out port provided at the upper part of the hot air drying means.
As a suitable means for classification of the deinked floss that has been dried, classification by a cyclone can be employed.

[Baking]
The deinked floss that has been dried and classified is sent to the first firing step. In the first firing step, it is important to adjust the unburnt rate to be 10 mass% or more and less than 15 mass%. By setting the unburned rate to 10% by mass or more, it is possible to impart porosity to the particles in the subsequent firing in the second firing step. Furthermore, by setting the unburned ratio to less than 15% by mass, it becomes possible to prevent the particles from being hardened by over-baking due to self-combustion in the next second baking step.
Firing is preferably performed at 650 ° C. or less, and in particular, in order to avoid a decrease in whiteness due to residual carbon, it is preferable to perform the steps in a range of 450 to 650 ° C. When calcination is performed at a high temperature exceeding 650 ° C., calcium carbonate is decomposed to become calcium oxide, and the inorganic substance may be melted to become inorganic particles having extremely high hardness and low porosity. In addition, since calcium oxide is water-soluble, it dissolves when added in the paper making process, and there is a possibility that, for example, chemical effects such as a sizing agent may be hindered.
The inorganic particle aggregate of this embodiment contains 90% by mass or more of the above porous raw material, and the porous raw material contains calcium, silicon and aluminum in terms of oxides of 30 to 82: 9 to 35: 9 to 35. It is characterized by including in the mass ratio. The mass ratio is preferably 40 to 82: 9 to 30: 9 to 30, more preferably 60 to 82: 9 to 20: 9 to 20.
In the first firing step and the second firing step, as a method for adjusting to the ratio of the present invention, the main point is to adjust the raw material composition in the deinking floss, but the drying / classifying step, the first firing step, In the second firing step, it is also possible to adjust the coating floss and the adjustment step floss, which have a clear origin, by means such as spraying or the like, or by means including the incinerator scrubber lime.
For example, neutral papermaking wastewater sludge and coated paper manufacturing process wastewater sludge are used to adjust calcium in inorganic particle aggregates, and silicon is added in large quantities as an opacity improver. Newspaper manufacturing wastewater sludge can be appropriately used for adjustment of aluminum. Papermaking wastewater sludge such as acidic papermaking system that uses sulfuric acid band or wastewater sludge in high quality papermaking process that often uses talc can be used.
As a technique for making the total content ratio of calcium, silicon and aluminum 90% by mass or more, use a flocculant which does not contain iron as a flocculant used for agglomeration treatment of drainage sludge, or design a manufacturing facility process using materials other than iron. It can be adjusted by lining and preventing iron from being mixed into the system due to wear and the like, and by installing and removing a high magnetic material such as a magnet in the drying / classifying equipment.
In particular, it is preferable to selectively remove iron, because it becomes a causative substance for decreasing whiteness due to oxidation.

[Dissolution / Crushing]
Since the inorganic materials fired from the first firing step and the second firing step have irregular particle sizes for use in the papermaking or coating step, there is a problem in using them as fillers and pigments as they are.
For use in fillers and pigment applications, it is necessary to make the particle size uniform and finer, but we have intensively studied the optimum particle size and pigment diameter for fillers and pigment applications in the inorganic particle aggregates according to the present invention. As a result, it was found that the inorganic particle aggregate of this embodiment preferably has an average particle size of 0.1 to 10 μm.
The inorganic particle aggregate of this embodiment has, for example, an oil absorption of 30 to 100 ml / 100 g, and when used as an internal additive in a paper making process, an average particle size of 0.1 to 10 μm and used as a pigment in a coating process For this, it is preferable to adjust the average particle size to 0.3 to 5 μm.
The inorganic particle aggregate of the present invention is preferably treated by the above-mentioned drying / classification / calcination method so that particles of 40 μm or less are already 90% or more before pulverization. This makes it possible to perform a one-stage pulverization process by a wet process without performing a multi-stage pulverization process such as the pulverization of large particles by dry pulverization and the atomization by wet pulverization which are generally performed conventionally. Thereby, the peak height of the average particle diameter in the differential curve of the particle size distribution by the Coulter counter method can be set to 30% or more. Furthermore, calcium, silicon and aluminum in the raw material sludge can be converted into oxides in an amount of 30 to 82: By adjusting to a mass ratio of 9 to 35: 9 to 35, the pore volume of the inorganic particle aggregate is 0.15 to 0.60 cc / g, the pore surface area is 10 to 25 m 2 / g, and the pore radius is 300. It can be ˜1000 angstroms.

EXAMPLES Hereinafter, examples will be shown to describe the present invention more specifically, but the present invention is not limited to these examples.
(1) Base paper configuration Basis weight 64 g / m ² . BPGW (30% by mass), NBKP (30% by mass), LBKP (25% by mass), DIP (15% by mass) and inorganic particle aggregates based on the present invention were added according to Example Table 2. The evaluation method is shown below.
(2) Hunter whiteness: JIS P 8148
(3) Hunter opacity: JIS P 8149
(4) Beck smoothness: JIS P 8119
(5) Ash content: JIS P 8251 (temperature 525 ° C.)
(6) Gloss on white paper: Murakami Color Research Laboratory: Gloss meter JIS P 8142
(7) Glossiness of printing: Using an RI printing aptitude tester (Meiji Seisakusho), the surface printed with 0.4 ml of offset printing ink was measured with a gloss meter by Murakami Color Research Laboratory. .
(8) Clarity of the image line portion: The clarity of the image line portion is visually determined. A: No blurring or blurring, B: Smearing is observed but no problem in use, △: Smearing is clearly evident, X: Many blurring / smearing.
(9) Ink back-through: Visually determine the back side of the paper after printing. A: There is no blur on the back surface, B: Smear on the back surface is observed but there is no problem in use, Δ: A blur on the back surface is clearly seen, X: There is a lot of blur on the back surface.
(10) Powder fall: On a black vinyl, 20 pieces of B5 size cut samples are bundled and shaken lightly 5 times, and the powder fall is judged visually. A: No powder fall is observed, O: Almost no powder fall, Δ: Powder fall is seen, X: Many powder fall off.
(11) Measurement of average particle diameter and particle size distribution: 10 mg of a sample was added to 8 ml of a methanol solution, and dispersed for 3 minutes with an ultrasonic disperser (output 80 watts). This solution was measured with a Coulter counter particle size distribution analyzer (TA-II type manufactured by COULTER ELECTRONICS) using an aperture of 50 μm. However, for those that could not be measured with a 50 μm aperture, measurements were made using a 200 μm aperture. The electrolyte used was ISOTON II (trade name; manufactured by COULTER ELECTRONICS, 0.7% high-purity NaCl aqueous solution).
(12) Oil absorption measurement: Measurement was performed according to JIS-K5101.
(13) Preparation of recording paper: An inorganic particle aggregate based on the present invention was added to 200 g of pure water based on Example Table 3, and a homodisper SL (trade name: manufactured by Tokushu Kika Kogyo Co., Ltd.) was used. After sufficiently dispersing, 200 g of a 10% aqueous solution of polyvinyl alcohol (PVA Kuraray R-1130) was added and mixed. This coating solution was coated on high-quality paper having a basis weight of 80 g / m ² using a bar coater (No. 60), and flattened with a pilot super calendar to obtain a recording paper.
(14) Recorded image evaluation: The recording paper obtained in (13) above was solid printed with an offset printing ink using an RI printing aptitude tester (manufactured by Meisei Seisakusho), and the density evaluation of the print density print image was performed. Printing was performed using a PIXUS9900i printer manufactured by Canon Inc., dot round print images, ink absorbency, and writing properties were evaluated, and surface strength was evaluated using cellophane tape.
a. Print density The density of the printed image was measured with a Macbeth RD918.
b. Magnified observation of dots with a magnifying glass on the dot circular print image.
A: The ratio of the shape close to a perfect circle is 95% or more.
B: 70% or more and less than 90%.
C: Less than 70%.
c. Ink Absorption Using 0.5 μl of magenta ink extracted from an ink cartridge of PIXUS9900i manufactured by Canon, the ink was dropped from a height of 1 cm onto a paper surface by a microsyringe, and the time until complete absorption was measured.
d. Written with a pencil of writing HB.
◯: Writable on the same level as copy paper.
Δ: Slightly inferior but can be written without problems.
X: What can hardly be written.
e. The surface strength was evaluated by the degree of peeling of the coating layer using cellophane tape.
○: Almost no peeling (high surface strength).
Δ: Peel off.
X: It peels considerably (surface strength is weak).
Production examples are shown in Table 1, and test results are shown in Tables 2 and 3.

The advantages of the present invention can be easily understood from the embodiments.
That is, in the ash content in Example Table 2, the yield includes calcium, silicon, and aluminum in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxides, and the calcium, What has a total content of silicon and aluminum of 90% by mass or more indicates a high ash content, which indicates that the yield in paper is high.
Regarding the bulkiness, it is shown from Example Table 2 that the inorganic particle aggregates have the same added amount, and the ash content is higher than that of the comparative production example inorganic particle aggregates, but the density is low. The effect is clear.
In order to see the effect of the inorganic particle aggregates based on the present invention, as is apparent from the results of Example Table 3 evaluated when used as a pigment in the coating layer, the inorganic particles based on the present invention It can be seen that the aggregate is superior in surface flatness, printability, and oil absorption compared to the inorganic particle aggregate of the comparative production example.

Claims (3)

An inorganic particle aggregate that can be used as a filler or pigment for papermaking,
Using the deinking floss discharged in the wastepaper deinking process as the main raw material,
Dehydration and drying, baking, resulting et been pulverized to an inorganic particle aggregates was adjusted to the following composition without adding a step for aggregating the particles after grinding step,
Oil absorption according to JIS K 5101 method is 30 to 100 ml / 100 g.
An inorganic particle aggregate characterized by that.
(composition)
The inorganic particle aggregate contains calcium, silicon, and aluminum as constituents of the inorganic particle aggregate in a mass ratio of 30 to 82: 9 to 35: 9 to 35 in terms of oxide, and the inorganic particle The inorganic particle aggregate whose total content rate of the said calcium, the said silicon, and the said aluminum is 90 mass% or more in an inorganic particle aggregate structural component among the particle structural components of an aggregate.   The inorganic particle aggregate according to claim 1, wherein an average particle diameter by a Coulter counter method is 0.1 to 10 µm.   The peak height of the average particle diameter in the differential curve of the particle size distribution by the Coulter counter method is 30% or more.
  The inorganic particle aggregate according to claim 1 or 2.