JPH03894A - Production of paper - Google Patents

Abstract

PURPOSE:To obtain paper having extremely improved yield on papermaking wire, excellent strength, whiteness and opacity by blending pulp slurry with light calcium carbonate having a specific particle shape as a loading material and making paper. CONSTITUTION:Pulp slurry is blended with light calcium carbonate satisfying conditions shown by the formula 3<=d/D<=15 [d is average particle diameter (mum) measured by particle size distribution measuring method of SEDIGRAPH X ray transmission and d is 1-5mum; D is average particle diameter (mum) calculated from value of specific surface area measured by BET specific surface area measurement] as a main loading material and paper is made. Preferably light calcium carbonate comprises >=50wt.% particles having 0.1-0.6mum D value and 1-5mum d and <=25wt.% particles having >=5mum d.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method for producing paper, and in particular, by incorporating a specific light calcium carbonate as a filler,
The present invention relates to a method for producing paper that has excellent paper strength, whiteness, and opacity, and that can significantly improve the yield on the wire during paper making.

``Prior art'' Generally, in paper making, paper properties such as whiteness, opacity, smoothness, writability, printability, etc., as well as paper texture,
In order to improve the texture, fillers are added to the valve slurry and paper is made.

As fillers, inorganic substances such as talc, kaolin, clay, diatomaceous earth, calcium carbonate, and titanium dioxide have traditionally been used, and in some cases, organic synthetic polymer substances such as urea formalin resin fine particles and micro hollow particles have been used. It is used. Among these fillers for papermaking, demand for calcium carbonate as a filler has increased with the development of neutral papermaking, which is effective for paper preservation, effective use of calcium carbonate, and closed papermaking system. is increasing.

By the way, calcium carbonate, which is used as a filler for paper making, is broadly divided into heavy calcium carbonate, which is produced by mechanically crushing and then classifying natural limestone, and light calcium carbonate, which is synthesized by chemical methods. .

Furthermore, methods for producing light calcium carbonate include a carbonation method in which carbon dioxide gas is blown into milk of lime to cause a reaction, and a carbonate solution formation method in which a carbonate is reacted with an aqueous calcium chloride solution or the like. Currently, the former carbonation method is often used. In addition, light calcium carbonate is classified into calcite type, arabnite type, and vaterite type based on the crystal type, and in general, those belonging to the calcite type are often used as fillers for paper making.

Regarding calcium carbonate as a filler for papermaking, heavy calcium carbonate has the advantage of having a good yield and less deterioration in paper strength. Its shape has sharp edges, and there are many drawbacks such as severe abrasion of the plastic wire during paper making, and poor whiteness and opacity of the paper.On the other hand, light calcium carbonate has a high scattering coefficient, so it is difficult to make paper. Plastic wire has excellent ability to improve whiteness and opacity, and has a relatively rounded shape, so plastic wire has good abrasion resistance, but has poor yield and poor paper strength. Decreased stiffness and stiffness have been pointed out as drawbacks. Therefore, light calcium carbonate has only been used in limited fields where paper opacity is particularly required, such as rice paper and India paper.

Light calcium carbonate, which is generally used as a filler for papermaking, has secondary particles that are spindle-shaped, needle-shaped, columnar, or cubic with locally rounded shapes, such as a rectangular parallelepiped, and the secondary particle size is It is about 0.05 to 1.0 μm. Usually, these fine light primary particles of calcium carbonate are often combined together to form aggregates, that is, secondary particles.By the way, these secondary particles are similar to primary particles. Because of this behavior, the properties of the original primary particles are sometimes lost, and the unique effects of light calcium carbonate may not be fully exhibited. In other words, the shape, agglomeration form, and particle size of light calcium carbonate particles greatly affect paper properties such as light scattering properties and paper-making conditions. It must be able to fully demonstrate its inherent properties and satisfy its basic properties as a filler.

Therefore, when using light calcium carbonate as a filler for papermaking, proposals have been made for techniques to improve the above drawbacks while taking advantage of these advantages.1 For example, calcium carbonate with a diameter of 0.1 to 0.3 μm A method of agglomerating particles and adding them to valve slurry (Japanese Patent Application Laid-open No. 5
4-1) No. 6405), a method in which aragonite columnar calcium carbonate having a length of 0.5 to 3 μm and a thickness of 0.1 to 0.3 μm is contained as a filler (JP-A-57-714)
99) and a method in which light calcium carbonate of cubic calcite crystals with an average particle diameter in the range of 0.3 μm to 3 μm is contained as a filler (Japanese Patent Application Laid-open No. 196795/1983).
Publication No.) etc. However, none of these methods has achieved the desired effect.

``Problems to be Solved by the Invention'' In view of the current situation, the present inventors aimed to use light calcium carbonate as a filler for paper making in a wide range of applications, and in particular, the present inventors have developed a paper with excellent strength, whiteness, and opacity. ,Moreover,
As a result of extensive research into a paper manufacturing method that can significantly improve the yield on papermaking wires, we have discovered that extremely superior effects can be obtained by incorporating light calcium carbonate with a specific particle shape as a filler. As a result, the present invention was finally completed.

"Means for Solving the Problems" The present invention is a paper manufacturing method in which light calcium carbonate is blended as a main filler into pulp slurry, and the light calcium carbonate satisfies the following conditions. .

d3≦d/D≦15 “d; Average particle diameter (μm) measured by Sedigraph X-ray transmission particle size distribution measurement method (d = range of 1 to 5 μm) Specific surface area measured by DiBET specific surface area measurement method Average particle diameter (μm) calculated from the value.""Effect" Valve slurry for papermaking generally contains various fillers, sizing agents, retention aids, freeness improvers, paper strength enhancers, dyes, pH
Conditioning agents, pitch control agents, slime control shavings, antifoaming agents, and other internal additives for papermaking are added as necessary, and sheets are formed and dried using long-length paper machines, twin-wire paper machines, etc. paper is manufactured by

In recent years, light calcium carbonate has come to be used as a general filler for papermaking, but as mentioned above, it has various drawbacks depending on its particle size and shape. .

As mentioned above, the present inventors aimed to use light calcium carbonate as a filler for paper making in a wide range of applications. As a result of intensive research and attention to light calcium carbonate that can significantly improve the yield of light calcium carbonate, it has been found that light calcium carbonate that satisfies the following conditions is the light calcium carbonate that is most suitable for the purpose of the present invention.

That is, 3≦d/D≦15 Average particle diameter (μm) measured by rcti Sedigraph X-ray transmission particle size distribution measurement method.

(Range of d-1 to 5 μm) D: Particle diameter (μm) calculated from the value of specific surface area measured by BET specific surface area measurement method. "Light calcium carbonate originally has a very strong cohesive force between primary particles, and usually many primary particles combine to form aggregates. This is how they aggregate. Light calcium carbonate is not completely separated into individual primary particles even when its slurry is processed, for example, in a wet grinder.

Therefore, the present inventors dispersed light calcium carbonate in water, treated it with a stirrer such as a tabletop propeller mixer, and measured the resulting slurry using a Sedigraph X'4IA transmission particle size distribution measurement method. The average particle diameter d is measured as the particle diameter of an aggregate, which is a so-called secondary particle, in which a large number of primary particles are combined, as if it were a primary particle. Therefore, d should be correctly interpreted as the average secondary particle diameter. (Hereinafter, d will be referred to as the secondary particle diameter.) On the other hand, the average particle diameter of light calcium carbonate calculated from the specific surface area measured by the BET specific surface area measurement method is:
Approximately, it can be defined as the original particle size, that is, the primary particle size.

(Hereinafter, D will be referred to as the primary particle diameter.) The light calcium carbonate used in the method of the present invention has a particle form most suitable as a filler for papermaking, but it has a particularly high whiteness compared to conventional light calcium carbonate. It has the characteristics of good properties and opacity, improved printing strength such as soaking strength, and high yield on papermaking wire.

Light calcium carbonate, which provides such excellent effects, has a secondary particle diameter d of 1 to 1, as measured by the Sedigraph X-ray transmission particle size distribution measurement method in an aqueous dispersion system. 5 μm, more preferably 1 to 4 μm
belongs to.

Further, it is necessary that the ratio between the secondary particle diameter d and the primary particle diameter calculated from the specific surface area measured by the BET specific surface area measurement method and expressed as the average particle diameter satisfies the following formula.

3≦d/D≦15 Incidentally, if the secondary particle diameter d, which is indicated by the average particle diameter measured in an aqueous dispersion system, is less than 1μ, it is not preferable because the yield and paper strength will decrease. If it exceeds darkness, the whiteness and opacity will drop significantly, which is undesirable.Furthermore, if the value of the above formula d/D exceeds 15, light calcium carbonate will form large aggregates and will not be able to absorb the light necessary for light scattering. Because the fine voids are reduced, the whiteness and brightness are significantly reduced, and if it is less than 3, the number of fine particles that are close to single crystals increases and the yield and strength of the paper decreases, so it is difficult to obtain the desired effect. I can't.

It should be noted that the light calcium carbonate used in the method of the present invention has a D value in the range of 0.1 to 0.6 μm to obtain satisfactory optical properties such as whiteness and opacity. can be used more preferably.

Furthermore, in the method of the present invention, the particle size distribution of light calcium carbonate as measured by the Sedigraph X-ray transmission particle size distribution measurement method is such that particles having a particle size of 1 to 5 μm account for 50% by weight or more, and Preferably, light calcium carbonate is used, in which the proportion of particles exceeding 25% by weight is less than 25% by weight.

Incidentally, of the light calcium carbonate used, 1 to 5μ
If the proportion of particles with a particle size of No effect is obtained. Furthermore, if the proportion of particles with a particle diameter of less than 1 μm exceeds 50% by weight, the yield decreases significantly, and
If the amount of particles exceeding 25% by weight exceeds 25% by weight, the abrasion properties of the plastic wire will deteriorate.

The light calcium carbonate used in the present invention is, for example, Japanese Patent Publication No. 42-14706, Japanese Patent Publication No. 55-51852, Japanese Patent Publication No. 57-30815, Japanese Patent Publication No. 59-12607,
JP 60-33765, JP 59-57913, JP 59-26927, JP 60-86067
JP-A No. 62-17020, etc., but the method is not particularly limited to these manufacturing methods. If necessary, these chemically synthesized calcium carbonates may be physically treated using a sand mill or the like.

In addition, the light calcium carbonate used in the method of the present invention includes slurry-like or cake-like quartz crystals, and powder products obtained by further drying these, and the manufacturing method and whether or not a dispersant is added may vary. etc., there are no particular limitations.

Furthermore, there are no particular limitations on the crystal structure or particle form of light calcium carbonate, but for example, it forms aggregates, the core of which is spherical or ellipsoidal, and has a shape such as a conpeitou, chrysanthemum, or sunflower shape. (hereinafter collectively referred to as konpeito-like), and those in which a large number of spindle-shaped or columnar primary particles are irregularly intertwined and bonded to form an aggregate. (hereinafter referred to as spindle-shaped entangled bodies and columnar entangled bodies, respectively); , collectively referred to as a prismatic road combination) or plate-shaped, and these are more preferably used as light calcium carbonate suitable for the purpose of the present invention.

In the present invention, light calcium carbonate is mainly used as a filler for papermaking, but since calcium carbonate is an alkaline filler and is easily decomposed by acid, a large amount of sulfuric acid is used. It is preferable to use it in a neutral papermaking system where paper is made in a weakly acidic to weakly alkaline manner rather than an acidic papermaking system, and in the method of the present invention,
As light calcium carbonate in the obtained paper, for example,
The desired effects of the present invention can be obtained by bundling 1 to 40% by weight per bulb.

Of course, fillers that are generally known and used as papermaking fillers in the paper manufacturing industry, such as talc, kaolin, calcined kaolin, clay, diatomaceous earth, heavy calcium carbonate, magnesium carbonate, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, alumino Mineral fillers such as silicates and bentonite, organic synthetic fillers such as polystyrene resin fine particles, urea-formalin resin fine particles, and fine hollow particles can also be appropriately selected and used in combination. Furthermore, pigments contained in waste paper, broque, etc. can also be effectively used as fillers.

In addition to these fillers, various conventionally used anionic, nonionic, cationic or amphoteric retention aids, paper strength enhancers, sizing agents, etc. may be appropriately selected and used in the pulp slurry. Ru. Specifically, various sizing agents such as petroleum resin-based sizing agents, alkyl ketene dimer-based sizing agents, alkenyl succinic anhydride-based sizing agents, styrene-acrylic anhydride-based sizing agents, stearic anhydride-based sizing agents, and rosin-based sizing agents. , polyacrylamide-based cationic, nonionic, anionic and amphoteric resins, polyethyleneimine and its derivatives, polyethylene oxide, polyamine, polyamide/polyamine and its derivatives, cationic and amphoteric starch, vegetable gum, urea-formalin resin, melamine Formalin resin, organic compounds such as hydrophilic polymer particles, aluminum compounds such as sulfate band, alumina sol, basic aluminum sulfate, basic aluminum chloride, basic polyaluminum hydroxide, ferrous sulfate, ferric chloride, One or more inorganic compounds such as colloidal silica and bentonite are used in appropriate combinations, and dyes, pH! Internal additives for papermaking, such as a PI conditioner, pitch control agent, slime control agent, and antifoaming agent, can also be added as appropriate depending on the use of the paper.

In addition, starch, polyvinyl alcohol,
It is also possible to apply various surface sizes, gradients, etc.

On the other hand, there are no particular limitations on the type of valve fiber, but for example, in addition to chemical valves such as softwood valves and hardwood valves obtained by MP, SP, AP, etc., and SEP, BCTMP, CTMP, CG, etc.
Various mechanical valves such as P5SGP STMP, RGP, waste paper valves such as DIP, non-wood valves such as hemp pulp, synthetic valves, etc. are used in appropriate combinations.

The method of the invention is applicable to all grades and types of paper products, such as book paper, newsprint, gravure paper,
In addition to printing paper such as cast coated paper, art paper, coated paper, and coated paper, as well as writing paper and packaging paper such as notebooks, information paper such as pressure-sensitive recording paper, thermal recording paper, electrostatic recording paper, and tank paper. It can be applied to a wide range of special papers such as

"Example" The present invention will be described in more detail with reference to Examples below, but of course the scope is not limited thereto. Further, "parts" and "%" in the examples indicate "parts by weight" and "% by weight", respectively, unless otherwise specified.

The quality of the obtained product was evaluated using the following method.

[Light calcium carbonate]

By the carbonation method, 17 types of light calcium carbonate M (A-Q) having the physical properties shown in Table 1 were prepared. None of the other calcium carbonates except for ■ contain a dispersant. Of the light calcium carbonate obtained,
ASBSC, D, E.S.J.

K, L, M, N, 05PSQ are cake-like quartz crystals with a solid content concentration of 65%, G is a slurry-like product with a solid content concentration of 25%, and H is a dry powder product. In addition, F was prepared by dispersing the synthesized light calcium carbonate M in water using a turbine blade stirrer so that the solid content concentration was 25%. The thus obtained dispersion was processed using a sand grinder (model 32G/manufactured by Igarashi Kikai Seizo Co., Ltd.) at a rotation speed of 1) 00 orp and a flow rate of 154 t/sin. In addition, ■ is a turbine in which calcium carbonate solid spectroscopy or 0.4% dispersant (trade name Nearon A-9/manufactured by Toagosei Co., Ltd.) is added to light calcium carbonate H so that the solid content concentration becomes 50%. It was produced by dispersing it in water using a blade stirrer.

Example 1 C, S, F, 450cc LBKP 90 parts and C, S, F
, light calcium carbonate A was added to the valve slurry in which 100 parts of valve consisting of 470 cc of NBKPIO was dispersed so that the content of the paper was 16%, and sulfate band 0 was added.
．． 5 parts, 0.5 parts of cationic starch (product name: 0NL-400, manufactured by Tamago Nasinal Co., Ltd.) and alkyl ketene dimer (product name: Sizevine-902, manufactured by Arayo Kagaku Co., Ltd.)
0.1 part was added with good stirring. This valve slurry is mixed with white water to dilute the valve slurry.
Finally, 0.02 part of anionic polyacrylamide (trade name: Barcol 155, manufactured by Allied Colloid) was added to prepare an inlet raw material.

Paper was made using a fourdrinier paper machine using the obtained inleft raw material to obtain paper having a weightage of 74 g/rrr.

In addition, the primary and secondary particle diameters and particle size distribution of the filler (light calcium carbonate), the whiteness and opacity of the paper, the pinking strength of the paper, the retention of the filler, and the abrasion resistance of plastic wires due to the filler particles. The following methods were used to measure and evaluate the results, and the results are shown in Table 1.
It was shown to.

(Measurement of -Primary Particle Size) Based on the specific surface area S measured by the BET specific surface area measurement method, the primary particle size was calculated using the following formula.

3.ρ D: Primary particle diameter of light calcium carbonate (μ layer) calculated from the value of specific surface area measured by BET specific surface area measurement method
- Specific surface area of light calcium carbonate (m"/g) determined by 3sBET specific surface area measurement method.

ρ: True specific gravity of light calcium carbonate (g/cm').

(Measurement of secondary particle diameter d) After calculating in advance that the amount of Le is 300 g in a 50 kl container, add water so that the final concentration is 25%, and then add the required amount of light calcium carbonate while placing it on the table. A slurry was prepared by stirring at 300 rpm for 10 minutes using a type propeller mixer. The slurry of light calcium carbonate thus obtained was measured using a Sedigraph X-ray transmission particle size distribution analyzer (manufactured by Shimadzu Corporation) to determine the cumulative weight of 5.
The particle size when the particle size reached 0% was measured, and the obtained value was taken as the secondary particle size. Furthermore, the cumulative weight % less than 1 μm, 1 to
The cumulative weight % of particles larger than 5 μm and the cumulative weight % of particles larger than 5 μm were also determined, and the particle size distribution of secondary particles was measured.

(Measurement of whiteness of paper) It was measured according to the method of JIS P8123.

(Measurement of paper opacity) It was measured according to the method of JIS P8138.

(Measurement of pinking strength of paper) Drybic (surface strength) test was conducted using R1 printing suitability tester manufactured by Mei Seisakusho, and judgment was made visually.

O: No bumps (good) Δ: Slight pick occurs ×; Many shocks occurred.

<Measurement of filler yield) Ash content a (%) in the inlet raw material and natural content b (%) in white water
) was measured and calculated from the following formula.

(Measurement of plastic wire wear amount) To measure the plastic wire wear amount, use the plastic wire for paper making (
Product name: os-so (manufactured by Nippon Filcon) width 2
5wn, length 250a+m, attach a 2.35g weight to the ceramic roll (diameter 100-m).
■) so that the contact angle is 90 degrees, and while rotating the roll at a circumferential speed of 500 m/win, add 1% of the filler.
The aqueous dispersion was circulated and supplied between the wire and the ceramic roll at a flow rate of If/sin, and the amount of weight loss (dry weight) of the wire after 120 minutes was measured, which was defined as the amount of wire wear.

(Particle shape of filler) The shape of the particles was observed using a secondary electron image using a scanning electron microscope.

Examples 2 to 1), Comparative Examples 1 to 6 In-left raw materials were prepared in the same manner as in Example 1, except that light calcium carbonate shown in Table 1 was used as a filler, and paper was made. Measurements and tests were carried out in the same manner as in 1, and the obtained results are shown in Table 1.

"Effects" As is clear from the examples in Table 1, by using the light calcium carbonate specified in the present invention as a filler and making paper, the paper has excellent strength, whiteness, and opacity. The filler yield on the machine wire was significantly improved, and the abrasion resistance of the plastic wire was also excellent.

Claims (2)

[Claims] (1) A paper manufacturing method in which light calcium carbonate is blended as a main filler into pulp slurry, characterized in that the light calcium carbonate satisfies the following conditions. 3≦d/D≦15 d: Average particle diameter (μm) measured by Sedigraph X-ray transmission particle size distribution measurement method (d = range of 1 to 5 μm) D: Specific surface area measured by BET specific surface area measurement method The average particle diameter (μm) calculated from the value of. (2) The particle size distribution of light calcium carbonate measured by Sedigraph X-ray transmission particle size distribution measurement method shows that particles with a particle size of 1 to 5 μm account for 50% by weight or more, and particles exceeding 5 μm account for 25% by weight or less. The method for producing paper according to claim (1).