JPH02293498A - Production of paper - Google Patents

Abstract

PURPOSE:To obtain a paper improved in stain of papermaking process and having excellent picking strength by adding a water-soluble polyvalent metal compound from which an alkaline earth metal is previously removed to a pulp slurry at a specific amount, controlling specific conductivity of the slurry to a specific value or below and then adding an alkaline filler thereto. CONSTITUTION:A water-soluble polyvalent metal compound (preferably aluminum compound) from which an alkaline earth metal is previously removed is added to a pulp slurry within the range of 0.05-10mm mol, preferably 0.1-8mm mol based on 100g pulp fiber content to control specific conductivity of the pulp slurry to <=1.5mS/cm, preferably <=1.2mS/cm and then an alkaline filler (preferably calcium carbonate) is added thereto and pulp slurry is made into paper to provide the aimed paper.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a paper manufacturing method, and is particularly effective in improving troubles caused by stains during preparation and papermaking processes, and furthermore,
This invention relates to a method for producing paper that can be adapted to high-speed paper machines and high ashing because it has improved paper strength such as picking strength, and extremely good drainage and yield on wire.

``Prior art'' In general, in paper making, in the preparation process, in order to improve the paper's quality characteristics such as whiteness, opacity, smoothness, writability, and printability, as well as the feel and texture of the paper, Paper is made by adding filler to pulp slurry. In recent years, quality requirements for these papers have become stricter, and on the other hand, due to the deterioration of the raw wood situation, high ash separation is progressing in order to save pulp. Furthermore, there is a need to reduce the weight of paper and support high-speed production, and as a result, there is an urgent need to establish technologies to improve paper strength or yield. Conventionally, in the acidic paper making method where paper is made in the acidic range of pH 4 to 6,
Sulfuric acid band has been widely used as a fixing agent for bulp fibers and fillers, and as a retention aid. On the other hand, in the neutral paper-making method where paper is made in weakly acidic to weakly alkaline conditions, alkaline fillers can be used, and calcium carbonate, as a typical example, is currently commonly used as a filler, and the demand for it is increasing year by year. in the direction.

By the way, in a papermaking method that uses calcium carbonate as an alkaline filler, for example, a water-soluble polyvalent metal compound exhibiting acidity or weak acidity, such as sulfuric acid, is added to pulp slurry containing calcium carbonate as an internal additive for papermaking. What happens is that carbon dioxide is generated through a chemical reaction with acid monocarbonate, causing a foaming phenomenon that causes foaming, or sticky hydroxides such as aluminum are generated and become deposits that may cause problems in the raw material preparation system or the like. This was a cause of so-called scale troubles that contaminated the inside of the paper machine system. Furthermore, adding sulfuric acid or the like to a neutral papermaking system has the problem of significantly reducing its effectiveness as a fixing agent or paper strength enhancer, as seen in acidic papermaking. They were not proactive about using the compound in neutral papermaking systems. Therefore, the reality is that a large amount of expensive retention improvers, tenacity enhancers, etc. are used as substitutes for improving the yield or increasing the strength of paper. .

However, on the other hand, it is cheap and easy to handle, and it is difficult to abandon the attractiveness of its effectiveness as a fixing agent and paper strength enhancer as seen in acidic paper making. It is also true that polyvalent metal compounds such as

For example, a method in which a specific metal salt such as sulfate is used after fixing a synthetic sizing agent (Japanese Patent Publication No. 64-6320);
A method of adjusting the zeta potential by adding an inorganic aluminum compound to pulp slurry containing calcium carbonate (Japanese Patent Publication No. 63-17958), a method of fixing an anionic emulsion with a specific metal salt (Japanese Patent Publication No. 17958/1983)
-18282) and a method of adjusting the zeta potential with cationic and anionic substances (Special Publication No. 61-63)
No. 796) etc. have been proposed. However, all of these methods are limited to techniques for improving the quality of paper, and are not fully satisfactory as techniques for solving problems such as foaming and staining, which should be considered problems as described above.

``Problems to be Solved by the Invention'' In view of the current situation, the present inventors aimed to improve troubles caused by stains during preparation and papermaking processes in papermaking methods that mainly use alkaline fillers, and to improve the picking strength. As a result of extensive research into ways to improve the strength of papers such as By specifying the specific conductivity after thoroughly mixing the pulp slurry, the polyvalent metal compound is sufficiently adsorbed to the pulp fibers, and as a result, the reaction with the alkaline filler is suppressed, and an extremely significant desired effect can be obtained. They discovered that "Means for Solving the Problems" The present invention provides a method for making paper by adding a filler, mainly an alkaline filler, to a pulp slurry. 0.05 parts by weight of the compound per 100 parts by weight of bulp fibers
This paper manufacturing method is characterized in that the alkaline filler is added within the range of ~10 mmol and the specific conductivity of the pulp slurry is adjusted to be 1.5 n+S/cm or less, and then the alkaline filler is added.

``Effect'' Generally speaking, pulp slurry for papermaking has IJ depending on its quality.
P, NKP, waste paper, etc. are blended, and various fillers, sizing agents, retention improvers, freeness improvers, paper strength enhancers, dyes, and other internal additives for papermaking are added as necessary. Then, sheets are formed using a fourdrinier paper machine, twin wire paper machine, etc., and then dried to produce paper.

In other words, pulp slurry is a slurry of pulp fibers such as LKP, NKP, and waste paper, which is processed either singly or in combination through a mixing stage using various preparation devices, that is, a pulper, refiner, and beating machine such as a dijordan. It passes through a pulp material chest, a liquid delivery pump, and a selection process such as screens and cleaners before being led to a wire bar.

Therefore, in the method of the present invention, a water-soluble polyvalent metal compound (hereinafter abbreviated as polyvalent metal compound) excluding alkaline earth metals is added in advance to the pulp slurry before adding the alkaline filler. , the alkaline filler is added after mixing and passing the pulp slurry using at least one of the above-mentioned preparation devices, but the effect of the polyvalent metal compound to be added is The most important feature is that the specific conductivity (hereinafter abbreviated as SC) is specified after adding polyvalent metal compounds and alkaline fillers so that the concentration of dissolved ionic substances does not become high in order to maximize the performance. It has the following.

Specifically, the polyvalent metal compound is added to the pulp slurry in an amount of 0.05 to 10 mmol, preferably 0.1 to 8 mmol, per 100 parts by weight of pulp fiber, and the SC is 1.0 mmol. 5 mS/cm or less, preferably 1.2
+*S/cai or less, but SC after addition of alkaline filler is 1.5 mS/c
ms/cm or less, preferably 1.2 ms/cm or less. Incidentally, SC is adjusted depending on the type of polyvalent metal compound, the amount added, the mixing conditions when adding it to pulp slurry, etc.
If the pulp slurry is prepared while the current exceeds 1.5 ms/cm, a large amount of dissolved ionic substances will react and bond with the alkaline filler, causing contamination in the raw material preparation system and paper machine system. This should be avoided as it can cause

In addition, by preparing the pulp slurry by the method of the present invention in this way, the SC of the pulp slurry is maintained at 1.5 ms/cm or less in any system, and the zeta potential is also adjusted to around O. It is something that

The preparation equipment used in the mixing step is not particularly limited and can be used as appropriate, but the polyvalent metal compound and the alkaline filler added later may come into direct contact with each other due to insufficient stirring of the equipment used. If a chemical reaction occurs, it is difficult to obtain the desired effect.

Therefore, it is more preferable to use an apparatus that can provide stirring power and contact time such that the polyvalent metal compound is almost uniformly dispersed in the pulp slurry and is sufficiently adsorbed to the pulp fibers.

For example, there is a method in which a polyvalent metal compound is added to a raw material chest containing pulp slurry and stirred, and then the compound is passed through a refiner, a liquid feed pump, etc., or a method in which an addition port for the polyvalent metal compound is provided and a liquid feed bomb is added. Examples include a method of adding from the inlet side, a method of disintegrating the pulp with water to which a polyvalent metal compound has been added in advance, or a method of diluting and mixing the pulp slurry.

The polyvalent metal compound used in the method of the present invention is not particularly limited, but for example, AI, Ti, Cr,
Fe, Co, Ni%Cu. ．． Zn, Zr, Sn, SbS
Halides such as Pb, oxyacid salts, organic acid salts, complex salts, etc., colloidal liquids easily dispersible in water, and basic aluminization represented by the general formula below? Examples include polyvalent metal compounds such as .

General formula (Ah(011).CI6-3-
■General formula (Ah(OH). (SO4) +6-
R)/■), ■(0<n<6, 1<m≦20) Among these polyvalent metal compounds, AI, Fe, Sn, Z
Chlorides, sulfates, organic acid salts, etc. of n, colloidal liquids, and basic aluminum compounds represented by the above general formula are particularly excellent in obtaining the desired effects of the present invention. Furthermore, from the viewpoint of toxicity, economic efficiency, whiteness, etc. of metal compounds,
Chlorides, sulfates, organic acid salts of AI, alumina sol, sodium aluminate, and basic aluminum compounds represented by the above general formula are preferably used. Also, if necessary, 1
It is also possible to use not only seeds but also two or more types of polyvalent metal compounds in appropriate combination. In addition, p of the slurry
The addition of various PLL adjusting agents to adjust H is not rejected.

The filler is mainly an alkaline filler,
Specifically, calcium carbonate, magnesium carbonate, etc. are mainly used, and calcium carbonate in particular is produced in large quantities, is economically inexpensive, and is industrially useful.

Calcium carbonate can be used regardless of its type, manufacturing method, shape, particle size, etc., such as calcite-based light calcium carbonate, arabite-based light calcium carbonate, dry-pulverized type, or wet-pulverized heavy calcium carbonate. etc. are appropriately selected depending on the purpose and quality of the paper, and can be used alone or in combination. In addition, fillers commonly known and used in the paper industry, such as mineral fillers such as talc, kaolin, clay, aluminum hydroxide, titanium dioxide, magnesium sulfate, silica, and bentonite, fine particles of polystyrene resin, fine particles of urea-formalin resin, fine hollow particles, etc. Organic synthetic fillers and the like may also be appropriately selected and used in combination. Furthermore, fillers contained in waste paper, broken paper, etc. can also be used effectively.

Of course, in addition to these, the pulp slurry also contains various conventionally used anionic, nonionic, cationic, or amphoteric retention aids, freeness improvers, paper strength enhancers, sizing agents, etc. Internal additives for papermaking are appropriately selected and used. Specifically, various sizing agents such as petroleum resin-based sizing agents, alkyl ketene dimer-based sizing agents, alkenyl succinic anhydride-based sizing agents, rosin-based sizing agents, and styrene-acrylic sizing agents, polyacrylamide or its cationic size organic compounds such as anionic and amphoteric modified products, polyethyleneimine and its derivatives, polyethylene oxide, polyamine, polyamide polyamine and its derivatives, cationic starch, urea-formalin resin, polyamide resin and hydrophilic polymer particles; One or more types of inorganic compounds such as colloidal silicate and bentonite are used in appropriate combinations, and dyes,
Internal additives for papermaking such as pH adjusters, pitch control agents, slime control agents, and antifoaming agents can be added as appropriate depending on the use of the paper. It is also possible to apply starch, polyvinyl alcohol, latex, various surface sizing agents, pigments, etc. to the surface of the sizing using a device such as a size press, gate roll or bill blade.

On the other hand, the pulp fibers are not particularly limited in their type, but include, for example, chemical pulps such as softwood pulp and hardwood pulp obtained by KPSSP, AP, etc., as well as SEP, BCTMP, CTMP, and CGP.
Various mechanical pulps such as , SGP, TMP, and RGP, waste paper pulps such as DIP, non-wood pulps such as hemp pulp, synthetic pulps, etc. are used in appropriate combinations.
The method of the present invention is applicable to all grades and types of paper products, such as printing paper and notebook paper such as book paper, newsprint, gravure paper, art paper, coated paper, cast paper, lightly coated paper, etc. It can be widely applied to writing paper and packaging paper such as, as well as information paper such as pressure-sensitive recording paper, heat-sensitive recording paper, electrostatic recording paper, and special paper such as tack paper. As mentioned above, the method of the present invention can be applied to polyvalent fillers, which have traditionally been problematic due to problems caused by stains during preparation and papermaking processes, especially in papermaking methods that mainly use alkaline fillers. This is an extremely preferred paper manufacturing method, as it allows the active use of metal compounds as internal additives for papermaking, and also provides extremely significant effects in terms of quality, such as improved tenacity. "Example" The present invention will be described in more detail with reference to Examples below, but it is of course not limited to these.

In addition, unless otherwise specified, parts in the examples indicate parts by weight based on the pulp fiber content, and the amount of the polyvalent metal compound added is expressed in millimoles based on 100 parts by weight of the pulp fibers. Example 1 0.5 mmol of sulfuric acid hand was added in advance to an LBKP chest containing LBKP, and the mixture was refined using a refiner to obtain c. s. f. was set to 450cc. This LBKP 7
Part 5 and 08s. f. Light calcium carbonate (product name: TP-121,
(manufactured by Okutama Kogyo Co., Ltd.) and 10 parts of talc were added and mixed. and cationic starch (product name: ONL-400,
0.5 part of Oji National Co., Ltd.) and 0.1 part of alkyl ketene dimer (trade name: Size Pine K-902, manufactured by Mkawa Chemical Industry Co., Ltd.) were added with thorough stirring, and this pulp slurry was diluted with white water. Further, 0.02 part of anionic polyacrylamide (trade name: Barcol 155, manufactured by Allied Colloid Co., Ltd.) was added to prepare an inlet raw material.

The obtained inlet raw material is made into paper using a long-length paper machine to produce paper of 6 m2
A paper of 0 g/nf was obtained. In addition, the pH and SC after LBKP passes through the refiner (measurement point A), the pH and SC after adding filler (measurement point B), the yield of all raw materials (%),
The ash retention (%), the picking strength of the paper, and the state of staining due to scale-like deposits were measured and evaluated using the following methods, and the results are shown in Table 1.

[Specific conductivity (SC)] Pulp slurry sampled at each measurement point was
LaserZee Model, which is a method of filtering with mesh wire and using a two-electrode cell for the filtrate.
500 (manufactured by PEMKEM).

[Yield of all raw materials]

The concentration A (%) of the inlet raw material and the concentration B (%) of white water were measured and calculated from the following formula.

A [Ash content retention] Ash content a (%) in the inlet raw material and ash content b (%) in white water
) was measured and calculated from the following formula.

a [Paper picking strength] Rl printing suitability test I! (manufactured by Mei Seisakusho) and visually evaluated using the following evaluation criteria.

◎: Very good with no occurrence of bumps.

O: Good with no pick occurrence.

Δ: Slight pick occurred.

×: Many picks occurred.

[Stain test]

The inlet raw material was filtered through a 100 mesh wire, and the filtrate 10042 was poured onto a stainless steel plate for 10 days at a flow rate of 100 ml/min while circulating. After washing with water, the degree of staining was visually evaluated using the following evaluation criteria.

◎: Excellent with no scale-like deposits.

O: Good staining with no scale-like deposits.

Δ: Slightly soiled with scale-like deposits.

×: There is a lot of staining due to scale-like deposits.

Example 2 An inlet raw material was prepared and paper was made in the same manner as in Example 1 except that 1 mmol of sulfuric acid was added to the LBKP chest in advance. Note that Table 1 shows the results of measurement or evaluation in the same manner as in Example 1.

Example 3 In Example 1, an inlet raw material was prepared and paper was made in the same manner as in Example 1, except that 3 mmol of sulfate was added to the LBKP chest in advance. Incidentally, the results of measurement or evaluation in the same manner as in Example 1 are shown in Table 1.

Example 4 In Example 1, an inlet raw material was prepared and paper was made in the same manner as in Example 1, except that 5 mmol of sulfate was added to the LBKP chest in advance. Note that Table 1 shows the results of measurement or evaluation in the same manner as in Example 1.

Example 5 An inlet raw material was prepared and paper was made in the same manner as in Example 1 except that 2 mmol of ferrous sulfate was added to the LBKP chest in advance in place of the band of sulfate. The results of measurements and evaluations in the same manner as in Example 1 are shown in Table 1.
It was shown to.

Example 6 Same as Example 1 except that 3 mmol of easily dispersible alumina sol in water (trade name: Alumina Sol 100, manufactured by Nissan Chemical Industries, Ltd.) was added to the LBKP chest in advance in place of the sulfuric acid band. The inlet raw material was prepared and paper was made. Note that Table 1 shows the results of measurement or evaluation in the same manner as in Example 1.

Example 7 An inlet raw material was prepared and paper was made in the same manner as in Example 1, except that 3 mmol of polyaluminum chloride was added in advance to the LBKr' chest in place of the sulfuric acid band. In addition, the results of measurement or evaluation in the same manner as in Example 1 are shown in Table 1.

Example 8 In Example 1, basic polyaluminum hydroxide (trade name: P
aho#2S. An inlet raw material was prepared and paper was made in the same manner as in Example 1, except that 3 mmol (manufactured by Asada Chemical Industry Co., Ltd.) was added. Incidentally, the results of measurement or evaluation in the same manner as in Example 1 are shown in Table 1.

Example 9 In Example 8, the addition to the LBKP chest was stopped, and 8 mmol of the polyaluminum hydroxide used in Example 8 was added to the bulker for disintegrating LBKP together with dilution water, and the mixture was beaten in a finer. In addition, an inlet raw material was prepared and paper was made in the same manner as in Example 8, except that the filler was replaced with 30 parts of heavy calcium carbonate (trade name: Softon I200, manufactured by Bihoku Funka Kogyo Co., Ltd.). In addition, the results of measurement or evaluation in the same manner as in Example 8 are shown in Table-1.

Comparative Example 1 In Example 1, an inlet raw material was prepared and paper was made in the same manner as in Example 1, except that sulfuric acid band was not added to the LBKP chest. Note that Table 1 shows the results of measurement or evaluation in the same manner as in Example 1.

Comparative Example 2 In Example 1, L8KP Chest was not added with sulfuric acid band, but was beaten in a refiner as it was, and 3 mmol of sulfuric acid band was added in the same equipment in which the filler was added. Inlet raw materials were prepared and paper was made. In addition, p■ and SC after passing through the LBKP finer (measurement point A) and pH and SC after adding the filler and sulfuric acid band (measurement point B) were measured or evaluated in the same manner as in Example 1. The results are shown in Table-1.

Comparative Example 3 An inlet raw material was prepared and paper was made in the same manner as in Comparative Example 2, except that 5 mmol of sulfate was added. In addition, the results of measurement or evaluation in the same manner as Comparative Example 2 are shown in Table 1.

Comparative Example 4 An inred raw material was prepared and paper was made in the same manner as in Comparative Example 2, except that 2 mmol of ferrous sulfate was added instead of sulfate band. The results of measurements and evaluations in the same manner as in Comparative Example 2 are shown in Table 1. Comparative Example 5 In Comparative Example 2, an inlet raw material was prepared and paper was made in the same manner as in Comparative Example 2, except that 3 mmol of polyaluminum hydroxide used in Example 8 was added instead of aluminum sulfate. In addition, the results of measurement or evaluation in the same manner as Comparative Example 2 are shown in Table 1.

"Effects" As is clear from the examples in Table 1, the paper obtained by the present invention can significantly improve staining during the preparation and papermaking processes, has a good raw material yield, and has good picking strength. We were able to obtain an improved paper.

Table-1

Claims (4)

[Claims] (1) In a method of paper making by adding a filler mainly consisting of an alkaline filler to a pulp slurry, a water-soluble polyvalent metal compound from which alkaline earth metals have been removed in advance is added to the pulp slurry in an amount of 100 parts by weight of pulp fibers. 0.05 to 1
A method for producing paper, which comprises adding an alkaline filler within a range of 0 mmol and adjusting the specific conductivity of the pulp slurry to be 1.5 mS/cm or less, and then adding an alkaline filler. (2) The method for producing paper according to claim (1), wherein the specific conductivity of the pulp slurry after adding the alkaline filler is adjusted to be 1.5 mS/cm or less. (3) Claim in which the alkaline filler is calcium carbonate (
The method for producing paper according to 1) or (2). (4) The method for producing paper according to claim (1), (2), or (3), wherein the water-soluble polyvalent metal compound is an aluminum compound.