JP2657285B2 - Papermaking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Objects of the Invention] (Industrial application field) The present invention greatly improves the strength of papermaking and yields fine fibers, fillers, sizing agents and other additives in papermaking raw materials. And a papermaking method which enables clarification of white water.

(Prior art) As a papermaking additive used in the papermaking process, a sizing agent for improving the writability and water resistance of papermaking, a paper-strengthening agent for increasing papermaking strength, and a yield for improving the yield of fillers and fine fibers. Various additives are used, such as an enhancer and a drainage agent that promotes drainage on a paper machine wire. For example, a water-soluble polymer substance is generally used as a paper strength enhancer or a retention aid, such as starch and modified starch, a water-soluble natural polymer substance such as a cellulose derivative, polyacrylamide and its derivatives, polyvinyl alcohol and its derivatives, and polyethyleneimine. And polyamide polyamine-epichlorohydrin resins, styrene-maleic acid resins and various other water-soluble polymers.

At present, the above-mentioned various papermaking additives are subject to many problems due to the advancement of papermaking technology.

For example, in the papermaking process, especially in the papermaking process of printing paper and writing paper, fillers are added for the purpose of improving the whiteness and opacity of the papermaking and reducing the raw material cost. There is a problem that as the filler content in the paper increases, the strength of the formed paper decreases, and a solution is needed. Also, from the viewpoint of long-term preservation of printed matter, the demand for so-called neutral paper obtained by making paper in a neutral or weak alkaline PH region without using a sulfuric acid band has become stronger, The conversion from acidic papermaking to neutral papermaking has been actively conducted,
The effect of the additive for neutral papermaking used in this is still insufficient, and improvement thereof is strongly desired.

Various solutions to these problems have been proposed, but recent patents show that starches are modified with cationic starch and / or cationic starch modified with a cationic imparting agent such as quaternary ammonium. Alternatively, a papermaking method using guar gum of amphoteric and colloidal silicic acid as a papermaking additive has been proposed (Japanese Patent Application Laid-Open No. 57-51900, published 58-582004).
No.), the effect of improving the strength of papermaking, the effect of improving the filler yield, etc., are not sufficiently satisfactory.

On the other hand, the present inventors have previously proposed a papermaking method using an acrylamide-based polymer having a cationic group and colloidal silicic acid as a papermaking additive in a raw pulp slurry for papermaking (JP-A-62-15391). No.), improvement of filler yield and improvement of papermaking strength are satisfactory, but not sufficiently satisfactory in fixing effect of the sizing agent.

(Problems to be Solved by the Invention) As described above, the demand for the performance of the papermaking additive becomes more severe with the deterioration of the raw material pulp situation, for example, the use of recycled paper pulp and the deterioration of the water quality of papermaking water. There is a need for the development of more effective papermaking additives.

In particular, the effect of the papermaking additive used for neutral papermaking is not yet satisfactory, and improving the yield of calcium carbonate used as a filler and increasing paper strength are important issues. Calcium carbonate is abundantly produced in Japan, and is an excellent papermaking filler having good properties at low cost, and its high content is extremely significant both economically and industrially. However, in order to obtain neutral paper containing a large amount of calcium carbonate filler, it is necessary to make the content of calcium carbonate in the raw material slurry extremely large. This causes various problems in operation, such as accelerating and paper breakage due to a decrease in wet paper strength. The use of filler retention aids can alleviate these problems, but their effects are still inadequate. Further, neutral paper having a high calcium carbonate content has a problem that various obstacles are likely to occur at the time of printing because the strength of the formed paper is low and the filler is easily dropped off from the surface.

An object of the present invention is to provide a new papermaking method that solves the above problems. More specifically, all known types of pulp such as various chemical pulp, mechanical pulp, waste paper regenerated pulp, pulp material composed of inorganic or organic natural or synthetic fibrous materials, and mixtures thereof, in addition to the various types of pulp of the present invention It is intended to provide a papermaking method that can be applied to all papermaking processes using as a raw material.However, when applied to a papermaking process that requires the blending of a filler, for example, the production of printing paper or writing paper, even better results are obtained. An object of the present invention is to provide a promising papermaking method, in particular, a papermaking method suitable as a neutral papermaking method using a calcium carbonate filler.

[Configuration of the invention]

(Means for Solving the Problems) As a result of intensive studies to solve the above problems, the present inventors have found that a specific vinyl-based monomer mixture is added as an additive for papermaking in an aqueous starch solution. The present inventors have found that the above object can be achieved by using a cationic group-containing graft starch copolymer obtained by copolymerization and colloidal silicic acid in combination, and have completed the present invention.

In general, the present invention comprises adding (A) a cationic group-containing grafted starch copolymer, and (B) colloidal silicic acid to a pulp slurry for papermaking raw material, and papermaking and drying according to a conventional method. And a papermaking method characterized by the following.

 Hereinafter, the configuration of the present invention will be described in detail.

(I) Regarding the cationic group-containing grafted starch copolymer component: The (A) cationic group-containing grafted starch copolymer component used in the present invention is prepared by adding a cationic group in an aqueous solution containing starch. It is obtained by polymerizing a monomer mixture essentially containing a functional group-containing monomer.

The starches used in the present invention are starch and / or modified starch, and more specifically, various starches made from wheat, rice, corn, potato, sweet potato, tapioca, etc., and modified starches thereof. Products, such as cationic starch, etherified starch, oxidized starch, and enzyme-modified starch, and one or more of them can be used. Of these, the use of cationic starch is particularly preferred.

Examples of the cationic group-containing monomer used in the present invention include mono- or di-alkylaminoalkyl (meth) acrylamide, mono- or di-alkylaminoalkyl (meth) acrylate, vinyl pyridine, vinyl imidazole, Mono- or di-acrylamines and mixtures thereof, furthermore, quaternary ammonium salts thereof, etc. can be exemplified.

Among them, dialkylaminoalkyl (meth) acrylamide, more specifically, dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, diethylaminoethyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide and their acids Salts or quaternary ammonium salts are preferred. One or two or more of these monomers can be used. Of these, dimethylaminopropyl (meth) acrylamide and its acid salts are particularly preferred.

In the present invention, in addition to the cationic group-containing monomer, a monomer such as (meth) acrylamide and (meth) acrylic acid can be used in combination. Preferred embodiments of the composition of the monomer mixture essentially containing the cationic group-containing monomer of the present invention include (1) dialkylaminoalkyl (meth) acrylamide or a quaternary compound thereof.
Mol%, (2) 2-10 mol% of (meth) acrylic acid,
(3) (meth) acrylamide is 65 to 96 mol%.

When the amount of (1) dialkylaminoalkyl (meth) acrylamide used is less than 2 mol% in each composition of the above monomer mixture, the paper strength enhancing effect and the yield improving effect become insufficient, and 25 mol% When the ratio exceeds the above range, it is economically disadvantageous, and in addition, the stability of the papermaking additive over time is deteriorated. On the other hand, if (2) the amount of (meth) acrylic acid is less than 2 mol%, the stability over time is poor, and if it exceeds 10 mol%, the paper strength enhancing effect is obtained.
The yield improvement effect and the size effect become insufficient.

In the present invention, the starch and / or modified starch is preferably used in an amount of 20 parts by weight to 60 parts by weight in preparing the cationic-containing grafted starch copolymer.
If the amount exceeds 60 parts by weight, and if the amount of the cationic group-containing monomer mixture used is less than 40 parts by weight, it is difficult to obtain a stable product, and the paper strength is enhanced. , The effect of improving the yield becomes insufficient. On the other hand, when the amount of the starch used is less than 20 parts by weight and the corresponding cationic group-containing simple substance mixture can generate 80 parts by weight,
Additives are expensive and cannot be avoided from economical restrictions during industrial use.

The cationic group-containing grafted starch copolymer of the present invention is obtained by dispersing 20 to 60 parts by weight of the above-mentioned starch in water, and then dissolving with heating to obtain a cationic group-containing monomer in an aqueous starch solution obtained. The mixture is obtained by adding 40 to 80 parts by weight of the mixture, sufficiently stirring and mixing, and then adding a polymerization initiator according to a conventional method to carry out polymerization. Specific examples of such polymerization initiators include peroxides such as hydrogen peroxide, potassium persulfate, ammonium persulfate, and alkyl hydroperoxides, and any redox initiator system and azo initiator composed of a combination of these with a reducing agent. Agents and the like.

It is to be noted that simply mixing a copolymer prepared by preliminarily polymerizing the above single-molecule mixture with starches results in inferior stability over time and insufficient effect.

The addition amount of the cationic group-containing grafted starch copolymer may be arbitrarily changed according to the purpose and the degree of the expected effect, but is generally 0.05 to 5%, preferably 0.05 to 5% based on the pulp dry weight of the raw pulp slurry. Is preferably 0.1 to 3%.

(Ii) Colloidal Silica Component: The colloidal silica (colloidal silica) used in the present invention preferably has a particle size of 50 mμ or less, particularly preferably 20 mμ or less. For example, various types commercially available from Nissan Chemical Industries, Ltd. under the trade name Snowtex have a particle diameter of 50 μm or less, and can be suitably used.

In carrying out the present invention, the amount of colloidal silicic acid added is
In general, 0.01 to 2% by weight of silicic anhydride (in terms of SiO ₂ ) based on the pulp dry weight of the raw pulp slurry is used, but a range of 0.05 to 0.5% is preferable. Colloidal silicic acid can exert a remarkable effect by interacting with a cationic group-containing grafted starch copolymer used in combination, and is not effective at all by itself. Therefore, it is desirable that the amount of addition be minimized.

(Iii) Papermaking method: In the papermaking method according to the present invention, other papermaking additives, for example, a sizing agent and the like can be added in a conventional manner.

However, in the papermaking method according to the present invention, since a very high retention effect, an excellent paper strength enhancing effect, and a size effect are exhibited, it is hardly necessary to use them together for the purpose before the addition for other papermaking. It goes without saying that the present invention does not refuse the use of these other papermaking additives at all.

The papermaking method of the present invention comprises adding a papermaking additive comprising the above-mentioned cationic group-containing grafted starch copolymer and colloidal silicic acid to a papermaking pulp slurry, followed by papermaking and drying according to a conventional method. The addition of the two can be performed in any order or simultaneously.

(Iv) Interaction between cationic group-containing grafted starch copolymer and colloidal silicic acid: The mechanism of the interaction between the two components has not been fully elucidated by the present inventors. However, there is no doubt that there is an interaction between the two, since the latter exhibits a great synergistic effect in the case of using both alone and the case of using both in combination. Currently, we speculate as follows. Colloidal silicic acid, particularly colloidal silicic acid sol suitably used in the practice of the present invention, has a very small particle size and a strong anionic property. Is considered to be adsorbed almost instantaneously. On the other hand, the grafted starch copolymer having a cationic group is gradually adsorbed on the surface of ordinary pulp fibers or fillers having weak anionic properties. When both of these are added to the raw pulp slurry, the above-mentioned reaction occurs simultaneously or sequentially to form an organic-inorganic composite of the cationic group of the cationic group-containing grafted starch copolymer and colloidal silicic acid. It is believed that a strong bond between the pulp fiber and the filler is formed through the pulp. When the cationic group-containing grafted starch copolymer contains an anionic group, the grafted starch copolymer containing the ionic group and the anion of the colloidal silica particles and the cationic group is contained. It is presumed that ionic cross-linking is formed between molecules with the cationic group therein to form a network structure, and the surprising paper strength enhancing effect, yield improving effect, and size effect of the present invention are exhibited.

(Examples) Hereinafter, the present invention will be described more specifically based on Adjustment Examples, Examples, and Comparative Examples, but these do not limit the scope of the present invention at all.

Preparation Example 1. 100 g of a 10% aqueous solution of a commercially available cationic starch (AMYLOFAX15, manufactured by AVEBE) cooked at 90 to 100 ° C., 45 g of a 40% aqueous acrylamide solution, 4.5 g of dimethylaminopropylacrylamide, and 0.4 g of acrylic acid , A mixture of 167 g of water
Adjust to pH 4.0 using 14.2 g of 10% sulfuric acid solution. Next, at a temperature of 50 ° C., 0.6% of a 2% ammonium persulfate (APS) aqueous solution,
0.6% aqueous solution of 2% sodium bisulfite (SBS)
The reaction was carried out at 60 to 70 ° C. for 3 hours to obtain a cationic group-containing grafted starch polymer (A) shown in Table 1 below.

Preparation Example 2. 157 g of an aqueous solution of a 10% concentration of a commercially available cationic starch (AMYLOFAX15, manufactured by AVEBE) cooked at 90 to 100 ° C., 40 g of a 40% solution of acrylamide solution, 6.6 g of dimethylaminopropylacrylamide, 1 g of acrylic acid, 10 mixture of 146 g of water
The pH is adjusted to 4.0 using 18.4 g of sulfuric acid. Next, mix 50
0.8 cc of a 2% ammonium persulfate (APS) solution at 0.8 ° C. and 0.8 cc of a 2% aqueous solution of sodium bisulfite (SBS) are added, and the temperature is 60-70.
C. for 3 hours to obtain a cationic group-containing grafted starch polymer (B) shown in Table 1 below.

Examples 1 to 2 Escalon # 800 (heavy calcium carbonate) 30% by weight in 1% pulp slurry of L-BKP (CSF330cc), neutral sizing agent (Colopearl X-11K, alkenyl succinic anhydride) 0.2% by weight and then the cationic group-containing grafted starch copolymers (A) and (B) obtained in Preparation Examples 1 and 2
After adding 0.3% by weight and mixing well, 0.1% by weight (in terms of SiO ₂ ) of colloidal silicate sol (Snowtex 30, particle diameter 10-20 μm, manufactured by Nissan Chemical Industries) was added and mixed well. Each prepared pulp slurry thus obtained was made and dried in a conventional manner using a TAPP1 standard sheet machine. After the obtained handmade papers were conditioned, the filler in the papers, the filler retention, the internal strength (1B), and the Stechig were measured. The results are shown in Table 3 below.

Comparative Examples 1-3 Instead of using the cationic group-containing grafted starch copolymers (A) and (B) in Example 1, the cationic group-containing polymers (a) and (b) in Table 2 below were used. ), Except that a cationic starch (c) was used, and a hand-made paper was obtained in the same manner as in Example 1. A similar paper quality test was performed on these handmade papers. The results are also shown in Table 3.

Example 3.4 Escalon # 800 (heavy calcium carbonate) 20% by weight in a 1% pulp slurry of pulp L-BKP (CSF420cc), neutral sizing agent (Colopearl X-11K, alkenyl succinic anhydride) 0.2 % By weight, the cationic-containing grafted starch copolymer (A) obtained in Preparation Examples (1) and (2),
After 0.3% by weight of (B) was added and mixed well, colloidal silicic acid (Snowtex S, particle diameter 7 to 9 μm,
Nissan Chemical Industry Co., Ltd.) (0.1% by weight (SiO ₂ equivalent)) was added and mixed well. Each of the prepared pulp slurries thus obtained was made and dried in a conventional manner using a TAPP1 standard sheet machine. After the obtained handmade papers were conditioned, the filler in the papers, the filler retention, the internal strength (1B), and the Stechig were measured. The results are shown in Table 4.

Comparative Example 4.5 A hand-made paper was obtained in exactly the same manner as in Example 3 except that the colloidal silicic acid (Snowtex S, particle diameter 7 to 9 μm, manufactured by Nissan Chemical Industries, Ltd.) was not added. A similar paper quality test was performed on these handmade papers. 4th result
It is also described in the table.

Comparative Example 6 Hand papermaking was performed in exactly the same manner as in Example 3 except that the cationic group-containing grafted starch copolymer (A) obtained in Preparation Examples (1) and (2) in Example 3 was not added. I got A similar paper quality test was performed on these handmade papers. The results are shown in Table 4.

In view of the results of the above-mentioned Examples and Comparative Examples, when the papermaking method according to the present invention was adopted, that is, a cationic group-containing grafted precipitated powder copolymer and colloidal silicic acid were added to the pulp slurry of papermaking raw material. Of acrylamide system containing cationic group, grafted starch copolymer containing cationic group, cationic cationic starch alone, or colloidal silicic acid alone It can be seen that excellent paper with a good balance in the internal strength (1B) effect and size effect was obtained.

〔The invention's effect〕

According to the papermaking method of the present invention, a very high filler retention effect can be obtained, and a paper having high strength and good size effect can be obtained. Therefore, even in papermaking using an expensive neutral sizing agent or when producing a paper with a high filler content, the neutral sizing agent and the filler are well adsorbed to the pulp fiber, so that the sizing agent for the raw pulp slurry, or Filler addition rate can be minimized, so that drainage on the paper machine wire is improved, wire abrasion is reduced, paper breakage is prevented by increasing wet paper strength, pitch contamination on wire blanket, etc. Various operability such as prevention of odors is improved. Also, the improvement in the filler retention rate is useful for reducing the solid particles (SS) suspended in the white water, thereby effectively utilizing the raw materials and reducing the load on the wastewater treatment. Further, the papermaking method of the present invention has a very high strength of the obtained papermaking, so that the filler content in the papermaking can be further increased, thereby saving pulp resources and greatly reducing papermaking costs. It has excellent industrial value.

Claims (9)

(57) [Claims] A papermaking method comprising adding (A) a cationic group-containing grafted starch copolymer and (B) colloidal silicic acid to a papermaking raw material pulp slurry, and papermaking and drying according to a conventional method. Method. 2. The papermaking method according to claim 1, wherein the papermaking raw material pulp slurry contains a filler. 3. The papermaking method according to claim 2, wherein the filler is calcium carbonate. 4. A method according to claim 1, wherein the grafted starch copolymer containing a cationic group is an aqueous starch solution comprising: (a) a monomer containing a cationic group and (b) a monomer containing (meth) acrylamide as an essential component. The papermaking method according to claim 1, 2 or 3, which is obtained by copolymerizing 5. An aqueous solution containing from 20 to 60 parts by weight of a starch, wherein the grafted starch copolymer containing a cationic group contains: (a) 2 to 25 mol% of a monomer containing a cationic group (b) And (c) 40-80 parts by weight of a monomer mixture containing (c) 2-10 mol% of (meth) acrylic acid. The papermaking method according to claim 4, wherein 6. The papermaking method according to claim 4, wherein the starch is a cationic starch. 7. The papermaking method according to claim 4, wherein the cationic group-containing monomer is dialkylaminoalkyl (meth) acrylamide. 8. The papermaking method according to claim 7, wherein the dialkylaminoalkyl (meth) acrylamide is dimethylaminopropyl (meth) acrylamide. 9. The method according to claim 1, wherein the colloidal silica has a particle diameter of 5 to 20 μm.
Item 6. The papermaking method according to item 4, item 4, or item 5.