JP3219007B2 - 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 method of adding a cationic or amphoteric acrylic water-soluble polymer to a stock in a papermaking process in a papermaking process, and mixing the resulting mixture with (meth). Acrylate
(Meth) acrylic acid polymer or (meth) a
Crylic acid copolymer [hereinafter referred to as (meth) acrylic acid (co) poly
Sometimes referred to as compound] Papermaking was added and mixed, to a papermaking method for improving the yield and / or drainage.

[0002]

2. Description of the Related Art Conventionally, in the papermaking process of papermaking, there has been a problem that the composition distribution in the thickness direction of the paper layer becomes uneven due to the outflow of various fillers added. In addition, there are also problems to be solved, such as an increase in cost due to outflow of raw materials and additive chemicals, and a need for a stock concentration of a certain value or more. In addition, the outflow of filler and the like also leads to contamination of the circulating white water. In order to solve these problems, certain types of retention aids have been added.

[0003] An increase in the papermaking speed during papermaking leads to an improvement in productivity. On the other hand, an improvement in the pulp beating degree is also desired from the viewpoint of increasing the paper strength. It was difficult to do. To solve this problem, a solution is added by adding a drainage improver.

[0004] The retention aid or drainage improver is generally a water-soluble polymer substance, that is, polyacrylamide and its derivatives, synthetic polymer substances such as polyethyleneimine, polyamide polyamine epichlorohydrin resin, starch and the like. And natural water-soluble polymer substances such as derivatives thereof.

Various methods have been proposed for the purpose of further improving the yield and / or drainage.
For example, a method of adding and mixing a cationic or amphoteric water-soluble polymer to a stock and then mixing and adding colloidal silica (Japanese Patent Application Laid-Open No. 27676/1995) contains 25 to 60 mol% of an anionic group. A method in which an anionic acrylamide-based polymer having a molecular weight of 100,000 to 1,000,000 is added to a stock, and then a cationic starch or a Hoffman reactant of polyacrylamide is added (Japanese Patent Laid-Open No. 60-185900).
Japanese Patent Application Laid-Open No. 62-191598), a method for improving the yield using a cationic polymer and bentonite
Various proposals have been made. Further, 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 (Japanese Patent Laid-Open No. 245998/1992). There is known a method for improving a filler yield by adding a mixture of a molecular compound and bentonite (Japanese Patent Application Laid-Open No. 64-61588).

However, the anionic polyacrylamide used in the above-mentioned method is an acrylate / acrylamide (co) polymer, which is used as a viscous aqueous solution. There was a drawback that the felt was stained. In addition, there has been a problem in terms of solubility. Furthermore, although these methods are intended to improve the yield or drainage more than the method using a water-soluble polymer alone, the situation of raw pulp due to the recent advancement of papermaking technology and the increase in waste paper usage rate However, it is not satisfactory because of the deterioration of water quality and the quality of papermaking water, and a method for further improving the yield or drainage has been strongly desired.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the yield in the papermaking process and the drying process by improving the yield of cellulose fibers and fillers and / or improving the drainage in the papermaking process. To improve it. For details, average the composition distribution in the thickness direction of the paper layer to produce high-quality paper, prevent outflow of raw materials and fillers, reduce costs, and make paper with high beatness pulp. It is another object of the present invention not to lower the paper making speed. Another object of the present invention is to improve the yield,
Another object of the present invention is to establish a stable papermaking method by keeping white water circulating clean by improving drainage. Further, the yield is improved, and /
Another object of the present invention is to provide a papermaking method that reduces the load in the white water recovery step and the load in the wastewater treatment step by improving drainage.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve these objects, and as a result, in the papermaking process of papermaking, a cationic or amphoteric acrylic-based water-soluble After adding and mixing the molecules, a (meth) acrylic acid (co) polymer is added and mixed, and the paper is made.
Alternatively, it has been found that the above object can be achieved by a papermaking method for improving drainage, and the present invention has been accomplished.

[0009] The first invention is a method for making paper in a papermaking process.
After adding a water-soluble polymer having a structure represented by the following formula (1) to the stock, shearing is performed, and then a dispersion polymerization method (polymerization with stirring in a salt aqueous solution in which the monomer is dissolved but the resulting polymer is not dissolved) is performed. Does not contain (meth) acrylate due to polymerization method)
(Meth) acrylic acid polymer or (meth) acrylic acid
A papermaking method characterized by adding and mixing a water dilution of a dispersion of polymer fine particles.

Embedded image (Wherein R ¹ is a hydrogen atom or a methyl group, R ² is an ethylene or propylene group, R ³ and R ⁴ are a methyl or ethyl group, R ⁵ is a hydrogen atom, a methyl group, an ethyl group or a benzyl group, and A is O or NH, X ⁻ represents a counter anion, and has a relationship of a + b + c = 100 mol%, a = 10 to 90 mol%, b = 10 to 90 mol%, and c = 0 to 30 mol%.

A second invention provides a water-soluble polymer represented by the formula (1) and the (meth) acrylic acid polymer or
The addition amount of the (meth) acrylic acid copolymer is stock SS per <br/> is, characterized in that each is 50-500 ppm.

[0011] In the third invention, the pH value of the stock is 6.5 to 6.5.
9.5.

A fourth invention is directed to the above (meth) acrylic acid heavy
When the compound or the (meth) acrylic acid copolymer has a (meth) acrylic acid: acrylamide molar ratio of 100: 0 to 15:
85 or a polymer or copolymer .

[0013]

DETAILED DESCRIPTION OF THE INVENTION The structure of the water-soluble polymer used in the present invention is a cationic or amphoteric water-soluble polymer containing a cationic vinyl monomer, and is a salt of dialkylaminoalkyl (meth) acrylate. Or a quaternized copolymer or a dialkylaminoalkyl (meth) acrylamide salt or quaternized copolymer.

The salt or quaternary dialkylaminoalkyl (meth) acrylate used for the water-soluble polymer of the present invention includes dimethylaminoethyl acrylate hydrochloride, dimethylaminoethyl methacrylate hydrochloride, acryloyloxyethyltrimethylammonium chloride, Examples thereof include methacryloyloxyethyltrimethylammonium chloride, acryloyloxyethyldimethylbenzylammonium chloride, and methacryloyloxyethyldimethylbenzylammonium chloride.

Further, dialkylaminoalkyl (meth)
Examples of the acrylamide salt or quaternary compound include dimethylaminopropylacrylamide hydrochloride, methylated product, and benzylated product.

The cationic monomer used in the water-soluble polymer of the present invention may be one kind or a mixture of two or more kinds.

The molecular weight of the water-soluble polymer of the present invention is desirably 3,000,000 or more. In the case of a low-molecular weight product, the effect of the present invention is not remarkably exhibited due to weak cohesive strength.

The (meth) acrylic acid (co) polymer used in the present invention may be a homopolymer of acrylic acid, methacrylic acid, itaconic acid or a copolymer with another nonionic monomer. Examples of the nonionic monomer that can be used here include acrylamide, methacrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, vinyl methyl ether, acrylonitrile, and methyl acrylate. Of the above monomers, the polymer used in the present invention is most preferably a (co) polymer of acrylic acid and acrylamide, the molar ratio of which is from 100: 0 to 15:85. The molecular weight of the (meth) acrylic acid (co) polymer is preferably 1
500,000 or more.

The (meth) acrylic acid (co) polymer used in the present invention is polymerized in an aqueous salt solution which dissolves the monomers used but does not dissolve the polymer produced, and provides a dispersion of polymer fine particles. What is obtained as is preferred. The production method includes a method disclosed in Japanese Patent Publication No. 46-14987. In the polymerization by this method, the coexistence of a dispersant such as a polymer electrolyte improves the stability of the obtained dispersion, which is more industrially advantageous. A water dilution of the polymer thus obtained is added to the stock.

Since the (meth) acrylic acid (co) polymer used in the present invention has very good dispersibility, even if it has a relatively high molecular weight, the above-mentioned problem of wire and felt contamination does not occur. In addition, since the polymer used does not contain (meth) acrylate, there is no problem of solubility, the viscosity is low, the fluid flows easily, and the material is very easy to handle. It does not require strong agitation to disperse and mix in water. The (meth) acrylic acid (co) polymer used in the present invention can be used in combination with colloidal silica and bentonite.

In the papermaking process, the amount of the water-soluble polymer represented by the formula (1) and the amount of the (meth) acrylic acid (co) polymer added are 50 to 500 p
pm, more preferably 100 to
300 ppm. If the amount of added chemicals is too small, the effect will decrease, and if it is too large, there will be adverse effects such as flock formation and deterioration of the quality of the papermaking, and furthermore, the contamination of the felt and wire used in the papermaking process is likely to occur Become.

In the papermaking method according to the present invention, the timing of adding each additive is not particularly limited, but a water-soluble polymer is first added, and then (meth) acrylic acid (co)
It is necessary to add a polymer. Preferably, in the papermaking process, it is preferable that the water-soluble polymer is added before the centriscreen in the papermaking process, and the (meth) acrylic acid (co) polymer is added after the centriscreen.

The pH of the stock used in the present invention is 6.5.
It is preferably from 9.5 to 9.5. Within the pH range, the (meth) acrylic acid (co) polymer is uniformly dispersed in the stock, and becomes a (meth) acrylate (co) polymer to increase the viscosity,
It is considered that a synergistic effect with the water-soluble polymer added in the previous stage exerts a cohesive force, thereby improving the yield and drainage.

[0024]

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.

[Synthesis Example of Cationic or Amphoteric Water-Soluble Polymer] A monomer having a composition shown in Table 1 is dissolved in deionized water so as to have a monomer concentration of 15% by weight. Sodium and 2,2′-azobis (2-amidinopropane) hydrochloride were added as polymerization initiators, and samples 1 to 4 were synthesized by aqueous solution polymerization. Table 1 also shows their molecular weights.

[0026]

[Table 1]

[Synthesis example of (meth) 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 prepared. Fifteen
Was dissolved in a 15% by weight aqueous solution of sodium sulfate to a concentration of 2,2'-azobis (2-amidinopropane) hydrochloride as a polymerization initiator after replacement with nitrogen.
Polymerization was performed at 50 ° C. for 10 hours, and Samples 5 to 8 of the fine particle polymer dispersed in the aqueous salt solution were synthesized. Table 2 also shows their molecular weights.

[Synthesis Example of (Meth) Acrylate Copolymer] A monomer having the composition described in Item 5 in Table 2 was dissolved in deionized water so as to have a monomer concentration of 10% by weight. After replacement with nitrogen, sodium bisulfite and 2,2′-azobis (2
-Amidinopropane) hydrochloride was added as a polymerization initiator, and Sample 9 was synthesized by aqueous solution polymerization. Table 2 also shows the molecular weight.

[0029]

[Table 2]

Example 1 Filler yield and total yield were measured by a brit type dynamic jar tester. The results are shown in Table-3. The paper stock used for the test was calcium carbonate 900pp
m, kaolin 300 ppm, pulp 4000 ppm, p
H8.1, CSF 300ml medium quality paper. The test was performed according to the following procedure. 500 ml of the stock is put into a brit type dynamic jar tester, stirring is started at 1500 rpm, and 0.1% by weight of the water-soluble polymer obtained in the synthesis example is obtained.
Add the aqueous solution. Timing starts from this time. Thirty seconds later, a 0.1% by weight (meth) acrylic acid (co) polymer diluted with water is added. After a further 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. Discard the white water for the first 10 seconds and then collect the white water for 30 seconds. Thus, the total yield and the filler ash at 600 ° C. were determined. The chemical addition amount is the addition amount per solid content of the stock. In Table-3, the first-stage polymer is the water-soluble polymer of the present invention described in Table-1, and the second-stage polymer is the (meth) acrylic acid (co) polymer of the present invention described in Table-2.

[0031]

[Table 3]

Example 2 A stock having a pH of 8.1 to 8.0 was prepared using a fourdrinier on-top paper machine.
Under the conditions of 3, a high quality paper having an ash content of 20% and a basis weight of 84.0 g / m ² was made. Filler composition is light calcium carbonate 8
0% and talc 20%. 50 g of cationic starch (corn starch raw material cationization rate: 3 mol%) per pulp in seed box
00 ppm was added, and the table
The water-soluble polymer described in No. 1 was added as a 0.15% by weight aqueous solution, and a 0.03% by weight (meth) acrylic acid (co) polymer diluting solution shown in Table 2 was added immediately after the centriscreen outlet. We make paper, and S of flow box and white water pit
From S and ash, the total yield and filler yield were determined. The results are shown in Table-4. The chemical addition amount is the addition amount per solid content of the stock. In Table 4, the first-stage polymer is the water-soluble polymer of the present invention described in Table 1, and the second-stage polymer is the (meth) acrylic acid (co) of the present invention described in Table-2.
It is a polymer. In all of the formulations of the present invention, a 10% or more improvement in papermaking speed was observed as compared with the case where the first-stage polymer was added alone.

[0033]

[Table 4]

[0034]

According to the papermaking method of the present invention, the yield of cellulose fiber and filler and / or the drainage can be improved in the papermaking process, thereby improving the productivity in the papermaking process and the drying process. Can be improved. Further, the papermaking method of the present invention can keep the circulating white water clean, and can further reduce the load in the white water recovery step and the load in the wastewater treatment step.

Claims (4)

(57) [Claims] In a papermaking process of papermaking, a water-soluble polymer having a structure represented by the following formula (1) is added to a stock, and then shearing is performed. A polymerization method in which polymerization is carried out with stirring in an aqueous salt solution that does not dissolve the coalescence)
(Meth) acrylic acid without (meth) acrylate
A papermaking method comprising adding and mixing a water diluent of a dispersion of fine particles of a phosphoric acid polymer or a (meth) acrylic acid copolymer . Embedded image (Wherein R ¹ is a hydrogen atom or a methyl group, R ² is an ethylene or propylene group, R ³ and R ⁴ are a methyl or ethyl group, R ⁵ is a hydrogen atom, a methyl group, an ethyl group or a benzyl group, and A is O or NH, X ⁻ represents a counter anion, and has a relationship of a + b + c = 100 mol%, a = 10 to 90 mol%, b = 10 to 90 mol%, and c = 0 to 30 mol%. 2. The water-soluble polymer represented by the formula (1) and the (meth) acrylic acid polymer or the (meth) acrylic acid.
The addition amount of acrylic acid copolymer is per stock SS, respectively 5
The papermaking method according to claim 1, wherein the amount is from 0 to 500 ppm. 3. The papermaking method according to claim 1, wherein the pH value of the paper stock is 6.5 to 9.5. 4. The (meth) acrylic acid polymer or
The (meth) acrylic acid copolymer has a (meth) acrylic acid: acrylamide molar ratio of 100: 0 to 15:85.
The papermaking method according to any one of claims 1 to 3, wherein the papermaking method is a polymer or a copolymer .