JP3260288B2 - Papermaking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking method in a papermaking process, and more particularly, to a papermaking process in a papermaking process in which cationic starch is added to and mixed with a stock, and then an acrylic acid (co) polymer is added and mixed. The present invention relates to a papermaking method for making paper and improving the yield and / or drainage.

[0002]

2. Description of the Related Art In a papermaking process, a papermaking method for adding and mixing a cationic or amphoteric water-soluble polymer to a paper stock and then adding and mixing colloidal silica or bentonite to improve paper retention and / or drainage is known. It is known.
Further, a method of adding an anionic acrylamide-based polymer having a molecular weight of 100,000 to 1,000,000 having an anionic group of 25 to 60 mol% to a stock, followed by adding a Hoffman reactant of cationic starch or polyacrylamide (Japanese Patent Laid-Open No. No. 60-185900) is known. There is also known a papermaking method in which a high molecular weight cationic polymer is first added to a papermaking cellulose slurry, and then a medium molecular weight anionic polymer is added (JP-A-4-245998). Further, a method of polymerizing acrylic acid / acrylamide in an aqueous salt solution in which the monomer is dissolved and the resulting polymer is not dissolved to obtain a dispersion of polymer fine particles (Japanese Patent Laid-Open No. 60-1859).
No. 00 publication) is known. However, there is no disclosure of a papermaking method in which an acrylic acid / acrylamide (co) polymer dispersion is added to a stock. Conventional anionic polyacrylamides are in the form of acrylate / acrylamide (co) polymers and are used as viscous aqueous solutions. When a viscous aqueous solution of an acrylate / acrylamide (co) polymer is added to the stock, there is a drawback that the wire and felt are stained.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to improve a papermaking method in a papermaking process. In a papermaking process, a cationic starch is added to a stock and then mixed with an acrylic acid (co) polymer. It is an object of the present invention to provide a method for making paper or paperboard which effectively improves the yield and / or drainage with good workability. One of the objects of the present invention is to produce a high-quality paper by averaging the composition distribution in the thickness direction of the paper layer by using a method for improving the yield of fillers, etc. The advantage of reducing paper stock density and controlling the variation of paper making it easier to mass-produce paper of a certain quality or extending the life of plastic wire An inexpensive papermaking method is provided. Another purpose of the present invention is to improve drainage. The purpose of drainage improvement is generally to increase papermaking speed, but it is often used for the purpose of enhancing paper strength.
That is, if the degree of beating of the pulp is improved, it is possible to increase the paper strength, but there is a disadvantage that the paper making speed is reduced. By using the method for improving drainage, it is possible to maintain the filtration speed and the drying speed of a wet paper web at the same level as pulp having a high degree of beating even for pulp having a high degree of beating. It is regarded as important as a papermaking method that enables the production of high-performance paper by making a stock using pulp with a high degree of beating without lowering the production speed. It is an object of the present invention to provide an inexpensive papermaking method that achieves the above object.

[0004]

Means for Solving the Problems The present inventors have found that by adding and mixing cationic starch to paper stock and then adding and mixing an acrylic acid (co) polymer, the yield and / or drainage can be improved. Reached.

[0005] The invention of claim 1 of the present invention relates to cellulose.
The pulp and filler are dispersed in water and the pH is adjusted to 6.5-10.
A sheet is formed from the pulp slurry maintained in the range and dried.
In the papermaking method of drying, the pulp slurry contains
After the starch is added, shear is applied and then the monomer is added.
Polymerization is carried out in an aqueous salt solution that dissolves and does not dissolve the produced polymer.
Acrylic consisting of a dispersion of the obtained polymer fine particles
A papermaking method characterized by adding a water diluent of an acid (co) polymer and papermaking.

In the invention of claim 2 of the present invention, the composition of the acrylic acid (co) polymer is such that the acrylic acid is 15 to 1 in all monomers.
The papermaking method according to claim 1 , wherein the papermaking method is a polymer of a monomer containing 00 mol% and 0 to 85 mol% of acrylamide.

[0007] The invention of claim 3 of the present invention is the papermaking method according to claim 1 , wherein the molecular weight of the acrylic acid (co) polymer is 1,000,000 or more.

The invention according to claim 4 of the present invention is characterized in that the addition amount of the cationic starch is 0.1 to 2% by weight per stock SS,
The amount of the acrylic acid (co) polymer to be added is 0.1% per stock SS.
2. The composition according to claim 1, wherein the content is 005 to 0.05% by weight.
Papermaking method described in 1.

[0009] The invention of claim 5 of the present invention is characterized in that the cationization rate of the cationic starch is 1 to 7 mol%.
A papermaking method according to claim 1 .

[0010]

[0011]

DETAILED DESCRIPTION OF THE INVENTION First, a limitation of the present invention is to disperse cellulose pulp and filler in water and adjust the pH to 6.5 to 10%.
Forming a sheet from the pulp slurry maintained in the range of
In a papermaking method for drying, after adding cationic starch to the pulp slurry, shearing is applied, and then monomer is added.
Polymerization is carried out in an aqueous salt solution that dissolves
Acrylic consisting of a dispersion of the obtained polymer fine particles
It is characterized by adding a water diluent of an acid (co) polymer to make paper. Acrylic acid (co) polymer is hardly soluble, and even if it has a high molecular weight, it has low viscosity and does not require strong stirring to be dispersed and mixed in the stock. (The acrylate (co) polymer is easily soluble in water, has a high viscosity, and has a drawback that it is difficult to uniformly disperse it in the stock.) Polymerization is carried out in an aqueous salt solution in which the polymer is dissolved and the produced polymer is not dissolved, and a dispersion of the obtained polymer fine particles can be mentioned. It is easy to add a water diluent to the stock. Second, a limitation of the present invention is that the composition of the acrylic acid (co) polymer is such that the acrylic acid (15 to 1)
It is characterized in that it is a polymer of a monomer containing 00 mol% and 0 to 85 mol% of acrylamide. Such a polymer composition has a favorable effect on the yield and drainage improving effect. A third limitation of the present invention is that the acrylic acid (co) polymer has a molecular weight of 1,000,000 or more. If the molecular weight is low, the desired effect cannot be obtained due to insufficient cohesion.
The substantial upper limit of the molecular weight of the acrylic acid (co) polymer is about 20,000,000, and if it exceeds this upper limit, there is a risk of causing felt staining. A fourth limitation of the present invention is that the addition amount of the cationic starch is 0.1 to 2% by weight per stock SS, and the addition amount of the acrylic acid (co) polymer is 0.005 to 0. It is characterized by being 0.05% by weight.
If the amount is too small, there is no effect of improving the yield and drainage. If the amount is too large, floc formation occurs and the quality of the formed paper is deteriorated. A fifth aspect of the present invention is characterized in that the cationic starch has a cationization ratio of 1 to 7 mol%. If the cationization ratio is 1 mol% or less, the effect of improving the yield and drainage is poor, and it is economically meaningless to make the cationization ratio 7 mol% or more.

The kind of starch used as a raw material of the cationic starch used in the present invention is not particularly limited. For example, it is known that corn starch, potato starch, oxidized starch using these as a raw material and the like are arbitrarily selected, and a cationizing agent is reacted with an ether bond or an ester bond to obtain a cationic starch. Can also be preferably used in the present invention. An amphoteric starch into which a smaller amount of an anionic group than a cationic group has been introduced by oxidation or anion modification is generally referred to as a cationic starch in the present invention as long as it is rich in cations. That is, when used in the present invention, there is no difference in the effect. The place where the cationic starch is added is usually added to the seed box, but any place can be selected before the fan pump. The acrylic acid (co) polymer can be added at any place within the range from the fan pump to immediately after the centriscreen. The acrylic acid (co) polymer may be added in a predetermined amount, or bentonite or colloidal silica may be added separately, or cationic polyacrylamide or amphoteric polyacrylamide may be added together with or separately from cationic starch. Included in the technical scope.

[0013]

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist.

(Cationic Starch Composition) Using the raw material starch shown in Table 1, the starch cationizing agent COPA-60S (3-chloro-2-hydroxypropyltrimethylammonium chloride) manufactured by Morin Chemical Co., Ltd. was treated with sodium hydroxide. The reaction was carried out under alkaline conditions to obtain a cationic starch used in Examples. Table 1 shows the composition of each cationic starch.
Shown in

[0015]

[Table 1]

[Synthesis Example of Acrylic Acid (Co) polymer] In a reaction vessel equipped with a stirrer, a nitrogen aeration tube and a temperature controller, a monomer having a composition shown in Table 2 was added to a monomer concentration of 10% by weight in saline (NaCl concentration). 10% by weight aqueous solution)
2,2′-Azobis (2-amidinopropane) hydrochloride was added as a polymerization initiator, and polymerized at 50 ° C. for 10 hours with stirring to obtain a fine particle polymer dispersed in an aqueous salt solution. Table 2 shows the monomer composition and molecular weight of each sample.

[0017]

[Table 2]

(Example-1) Table 3 shows the results obtained by measuring the filler yield and the total yield by a brit type dynamic jar tester. The stock used in the test was 900 ppm charcoal, 300 ppm kaolin, and 4000 pulp.
ppm, PH 8.1, CSF 300 ml medium quality paper. The procedure is as follows. 500 ml of the stock is charged into a brit type dynamic jar tester, stirring is started at 1500 rpm, and a 0.1% by weight aqueous solution of the cationic starch described in Table 1 is added 30 seconds after the addition, and 0.1% of the polymer described in Table 2 is added. Add the% water dilution. After another 30 seconds, the cock for collecting white water is opened, and the white water that has passed through the 150 mesh wire is allowed to flow out. Discard the white water for the first 10 seconds, then collect the white water for 30 seconds and use it for measurement. Total yield and 600 ° C
And the filler yield was determined. The chemical addition amount is an addition amount per solid content with respect to paper amount.

[0019]

[Table 3]

(Example-2) The ash content of the paper was set to 20 using a fourdrinier on-top paper machine under the conditions of a stock pH of 8.1 to 8.3.
%, High-quality paper having a basis weight of 84.0 g / m ² was made. The filler composition is 80% light calcium carbonate and 20% talc. The cationic starch was added to the seed box as shown in Table 1,
Immediately before the entrance of the centrifugal screen, paper making was performed by adding a 0.03% by weight water diluent of the polymer described in Table 2 and the total yield and filler yield were determined from the SS and ash of the flow box and the white water pit. The results are shown in Table-4. The chemical addition amount is an addition amount per solid content with respect to paper amount. In all of the formulations of the present invention, an improvement in papermaking speed of 10% or more when no acrylic acid (co) polymer was added was observed.

[0021]

[Table 4]

[0022]

According to the papermaking method of the present invention, the yield of cellulose fiber and filler can be improved in the papermaking process, and the effect of increasing the papermaking speed is also recognized. The use of a high molecular weight acrylic acid (co) polymer effective for agglomeration under low viscosity and good workability conditions has a great economic value to achieve the above object.

Claims (5)

(57) [Claims] 1. A papermaking method in which cellulose pulp and a filler are dispersed in water, a sheet is formed from a pulp slurry in which the pH is maintained in a range of 6.5 to 10, and a cationic starch is added to the pulp slurry. After that, shear is applied, and then the monomer is dissolved and the resulting polymer is not dissolved.
Polymerization is performed in an aqueous salt solution, and the resulting polymer fine particles are
A paper-making method, comprising adding a water-diluted solution of an acrylic acid (co) polymer composed of a dispersion and making the paper. 2. The composition of the acrylic acid (co) polymer is a monomer polymer containing 15 to 100 mol% of acrylic acid and 0 to 85 mol% of acrylamide in all monomers. The papermaking method according to claim 1 , wherein 3. An acrylic acid (co) polymer having a molecular weight of 10
2. The papermaking method according to claim 1 , wherein the number is at least 10,000. 4. The amount of cationic starch added is from 0.1 to 2% by weight per stock SS, and the amount of acrylic acid (co) polymer is from 0.005 to 0.05% by weight based on stock SS. The papermaking method according to claim 1 , wherein the papermaking method is used. 5. The papermaking method according to claim 1, wherein the cationization rate of the cationic starch is 1 to 7 mol%.