KR20210019016A - Paper and cardboard manufacturing method - Google Patents

Abstract

The present invention comprises a papermaking process using a paper having a cation requirement of 100 μeq/L or more as a papermaking material, and a cation charge density of 200 to 1000 μeq/g, and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g. There is provided a method for producing paper and paperboard in which an onactive polyacrylamide is added to a stock in a range of 0.005 to 0.1% by mass based on the solid content of the battery.

Description

Paper and cardboard manufacturing method

The present invention relates to a method for manufacturing paper and cardboard.

Papermaking is currently carried out by going through a papermaking process in which a raw material slurry obtained by dispersing a pulp raw material in water is paper-making. In the papermaking process, a large amount of white water containing fine fibers and fuel is discharged from a paper machine or the like. The white water discharged is recycled and used during the papermaking process from the viewpoint of effective utilization and reuse of water resources.

Among the papermaking materials, various anionic substances such as resins, sizing agents, fluorescent dyes, and latex are contained. In particular, due to the improvement of the mixing ratio of the deinking pulp, mechanical pulp, and waste paper contained in the papermaking material, or the reuse of white water, anionic trash tends to accumulate in the paper manufacturing process, resulting in a decrease in the yield or on the wire. When a paper layer is formed in the paper, fiber, fuel, and other additives, which are the raw materials of the paper, pass through the wire, causing a disturbance in which it flows into white water.

For example, in Patent Document 1, after adding a specific water-soluble polymer (A) to the papermaking material before dilution with white water, the papermaking material is diluted with white water, and then a specific water-soluble polymer (B) is added, A method for suppressing the occurrence of defects in paper by impeding substances such as anionic trash, micro pitch, and turbidity components, characterized in that papermaking is performed by appropriately adding a yield improving agent, is described. In the above method, by adding a specific water-soluble polymer to the papermaking material, the charge of the anionic trash is neutralized, and the micro pitch and turbidity components are fixed to the pulp fiber, and as a result, the unfixed micro pitch and the turbidity component are aggregated. It is preventing them from being collected.

Japanese Unexamined Patent Application Publication No. 2009-249756

As a water quality indicator, when the cation requirement is 100 μeq/L or more (for example, the measured value of a PCD measuring device manufactured by Mutek), anionic trash increases. When a large amount of various cation polymers such as a coagulant, a yield agent, and a power agent are added to neutralize the charge of a large amount of anionic trash, a large amount of anionic trash aggregated in the strong cation is agglomerated and papermaking process Because it becomes easy to adhere to tools and equipment in the machine, a problem that the situation worsens often occurs. Also in the method described in Patent Document 1, if the amount of anionic trash increases, a sufficient effect cannot be obtained.

The present invention has been made in view of this situation, and even when a large amount of anionic trash is included in white water in the papermaking process, the amount of free water is increased, the yield is improved, and the turbidity is reduced. It aims to provide a manufacturing method.

In order to solve the above problem, the present inventors have repeatedly conducted extensive research and found that the problem can be solved by adding a specific low cationic polyacrylamide in a specific amount with respect to the total stock solid content.

The present invention has been accomplished based on the above findings.

That is, the disclosure of the present application relates to the following.

[1] A papermaking process using paper with a cation requirement of 100 μeq/L or more as a papermaking material, and a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g A method for producing paper and board, wherein polyacrylamide is added to a stock in an amount of 0.005 to 0.1% by mass based on the solid content of the previous stock.

[2] The method for producing paper and cardboard according to [1], wherein the stock material is a papermaking material containing mechanical pulp.

[3] The method for producing paper and cardboard according to the above [1], wherein the paper stock is a papermaking material containing 30% by mass or more of deinking pulp.

[4] The method for producing paper and cardboard according to [1], wherein the stock material is a papermaking material containing 30% by mass or more of used paper pulp.

According to the present invention, even when a large amount of anionic trash is included in white water in the papermaking process, it is possible to provide a method of manufacturing paper and cardboard capable of increasing the amount of free water, improving yield, and reducing turbidity. .

1 is a block diagram showing a method of manufacturing paper and cardboard according to an embodiment of the present invention.

The method for manufacturing paper and cardboard according to an embodiment of the present invention (hereinafter, sometimes referred to as ``this embodiment'') is a paper material having a cation required amount of 100 μeq/L or more as a papermaking material. A papermaking process using, and cationic polyacrylamide having a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g is obtained from 0.005 to the solids of the paper stock. It is characterized by adding to the stock in the range of 0.1% by mass.

When a paper stock having a cation requirement of 100 µeq/L or more is used as the papermaking material, a large amount of anionic trash is contained in white water in the papermaking process. On the other hand, in this embodiment, by adding a specific amount of cationic polyacrylamide having a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g relative to the solid content of the battery material, anionic trachea Agglomeration of the city can be suppressed, thereby increasing the amount of free water, improving the yield, and reducing turbidity.

The cationic polyacrylamide used in the method for producing paper and paperboard according to the present embodiment has a cation charge density of 200 to 1000 µeq/g. Here, the cation charge density refers to the number of equivalents (μeq/g) of the cation charge in the monomer units constituting the polymer.

If the cation charge density is less than 200 μeq/g, the amount of free water may decrease, and if it exceeds 1000 μeq/g, the effect of reducing turbidity may not be obtained. From this viewpoint, the cation charge density is preferably 200 to 700 µeq/g, more preferably 200 to 300 µeq/g.

The cation charge density can be obtained by the method described in Examples.

The cationic polyacrylamide has an intrinsic viscosity (η) of 2.7 to 18.3 dL/g. If the intrinsic viscosity (η) is less than 2.7 dL/g, since the molecular weight of the cationic polyacrylamide is too small, the range in which an aggregation reaction can occur is narrow, and there is a fear that a sufficient yield effect cannot be obtained. In addition, when the intrinsic viscosity (η) exceeds 18.3 dL/g, the molecular weight of the cationic polyacrylamide is too large, so that the viscosity is high and there is a concern that the effect of increasing the amount of free water may not be sufficiently exhibited. From this viewpoint, the intrinsic viscosity (η) is preferably 9 to 18 dL/g, more preferably 13 to 18 dL/g.

In addition, the intrinsic viscosity (η) is measured by measuring the flow time at 30°C using a Cannon-Fenske type viscometer, and the Huggins equation and Mead-Fuoss It is calculated using the equation.

The cationic polyacrylamide is not particularly limited as long as the cation charge density and intrinsic viscosity (η) are within the above ranges, and for example, an acrylamide monomer and a cationic monomer are used in an aqueous polymerization method, an emulsion polymerization method, or a suspension. It can be obtained by synthesizing by a known polymerization method such as a legal method. The charge density is adjusted by the mixing ratio of the monomer to be used, and the intrinsic viscosity is adjusted by the polymerization temperature, the monomer concentration, and the amount of initiator added.

Examples of cationic monomers include (meth)acrylic acid ester derivatives such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate; (Meth)acrylamide derivatives such as dimethylaminopropyl (meth)acrylamide and diethylaminopropyl (meth)acrylamide; Quaternary salts and acid salts of dimethylaminoethyl (meth)acrylate; Tertiary amino monomers such as allylamine and diallylamine, tertiary amine monomers, quaternary salts and acid salts thereof, and the like. Among them, a quaternary salt of dimethylaminoethyl (meth)acrylate is preferably used.

These cationic monomers can be used alone or in combination of two or more.

The blending ratio of the cationic monomer to the total amount of the monomer derived from all the structural units of the cationic polyacrylamide is preferably 0.5 to 9.5 mol%, more preferably 1 to 8 mol%. to be. By setting the mixing ratio of the cationic monomer within the above range, the cation charge density of the cationic polyacrylamide can be within the above range.

In addition, the blending ratio of the acrylamide monomer to the total amount of the monomer from which all the structural units of the cationic polyacrylamide are derived is preferably 90.5 to 99.5 mol%, more preferably 92 to 99 mol%.

The polymerization initiator used when preparing the cationic polyacrylamide is not particularly limited, and examples thereof include ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, and tert-butyl peroxide. . One or two or more polymerization initiators can be used.

In addition, in order to adjust the viscosity of the cationic polyacrylamide to be synthesized, it is preferable to use a chain transfer agent. The chain transfer agent is not particularly limited, and examples thereof include chlorine tetrachloride, chloroform, and carbon tetrachloride. One or two or more chain transfer agents may be used.

1 is a block diagram showing a method of manufacturing paper and cardboard according to an embodiment of the present invention.

The papermaking system 10 includes a raw material system 20, a composition/papermaking system 30, and a recovery system 40.

The raw material system 20 manufactures pulp from paper raw materials. The raw material system 20 in this embodiment includes a first raw material tank 21 and a second raw material tank 22. The first raw material tank 21 includes chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), and unbleached softwood kraft pulp (NUKP); Mechanical pulp such as ground pulp (GP), thermo-mechanical pulp (TMP), chemical thermo-mechanical pulp (CTMP), and refiner mechanical pulp (RMP) is accommodated, and in the second raw material tank 22, corrugated waste paper pulp, liner Used paper pulp such as old paper pulp, old magazine pulp, newspaper old paper pulp, paper roll old paper pulp, top white old paper pulp and deinked old paper pulp are accommodated.

The pulp accommodated in the first raw material tank 21 and the second raw material tank 22 is supplied to the mixing chest 23 at an appropriate ratio and mixed in the mixing chest 23. The mixed pulp is transferred to a seed box 25 after a papermaking chemical such as a viscosity agent is added in the machine chest 24.

The first raw material tank 21, the second raw material tank 22, the mixing chest 23, the machine chest 24, and the seed box 25 constitute the raw material system 20 of the present embodiment.

The composition and papermaking system 30 makes pulp and papermaking. The pulp accommodated in the seed box 25 is supplied to the white water silo 31 and then sequentially supplied to the cleaner 33 by the pump 32. In addition, it is supplied to the screen 36 by the pump 35, and is supplied to the inlet 37 after removing foreign substances therefrom. The inlet 37 suppresses the occurrence of flocks and stripes by supplying pulp to the wire of the wire part 38 at an appropriate concentration, speed, and angle. The supplied pulp is dehydrated in a wire part 38 and a press part not shown in the figure, and then dried in a dryer part not shown in the figure, and then appropriately treated to make paper.

Here, the liquid separated from the wire part 38 is white water 39. In addition, the white water 39 contains microfibers derived from raw material pulp used for papermaking, and other papermaking agents.

The white water 39 separated from the wire part 38 is stored in the white water silo 31. The white water stored in the white water silo 31 is partially supplied to the pump 32, and the rest is supplied to the white water recovery device 41.

From the white water silo 31 to the wire part 38 constitutes the composition and papermaking system 30 of this embodiment.

The recovery system 40 recovers white water from the composition/choji system 30. The supplied white water is transferred to the white water recovery device 41, and is filtered by the white water recovery device 41 to separate solid and liquid. The solid content is transferred to the machine chest 24, and the filtrate is recovered and stored in the recovery water tank 42. Part of the filtrate is filtered again, discharged to the outside, or used as conditioning water for adjusting the concentration of circulating white water.

The white water recovery device 41 and the recovery water tank 42 constitute the recovery system 40 of the present embodiment.

The white water and the adjusted water may contain a small amount of a paper-making agent within a range that does not impair the effects of the present invention.

The paper-making agent is not particularly limited, and for example, surfactant, wax, sizing agent, filler, rust inhibitor, conductive agent, defoaming agent, slime control agent, dispersant, viscosity modifier, coagulant, coagulant, strength enhancer, And a yield enhancer, an anti-stake agent, and a bulking agent.

The addition of the cationic polyacrylamide to the stock (pulp) is a supply line from the mixing chest (23) to the machine chest (24) of the pulp or the machine chest (24) (I), the seed box from the machine chest (24). Transfer line to (25) or seed box (25) (II), supply line from seed box (25) to white water silo (31) or from white water silo (31) (III), pump (32) from white water silo (31) Supply line or pump (32) (IV) to furnace, supply line from pump (32) to cleaner (33) or cleaner (33) (V), supply line from cleaner (33) to pump (35) or pump (35) (VI), pump 35 to screen 36 supply line or screen 36 (VII), screen 36 to inlet 37 supply line or inlet 37 (VIII), wire part The transfer line (IX) to the white water silo 31 separated from (38), the transfer line from the white water silo 31 to the white water recovery device 41, or the white water recovery device 41 (X). I can. Among them, from the viewpoint of suppressing agglomeration of anionic trash, the addition of cationic polyacrylamide is preferably any one of the above (IV), (V), (VI), (VII) and (VIII). , Any one of the above (VI), (VII) and (VIII) is more preferable.

In the method for producing paper and paperboard of the present embodiment, since agglomeration of anionic trash can be suppressed by adding cationic polyacrylamide, 30 mass of papermaking support material including mechanical pulp and deinking pulp are used as the stock material. It is possible to use a papermaking material containing not less than% and a paper making material containing 30% by mass or more of used paper pulp.

The amount of the cationic polyacrylamide added is 0.005 to 0.1% by mass based on the solid content of the battery. If it is less than 0.005% by mass, the agglomeration effect is low, and the yield and water purification effect cannot be sufficiently exhibited. In addition, if it exceeds 0.1% by mass, the agglomeration effect is too strong, and there is a possibility that the quality of the product is affected. From such a viewpoint, the addition amount of the cationic polyacrylamide is preferably 0.01 to 0.08% by mass, more preferably 0.02 to 0.06% by mass, based on the solid content of the battery material.

(Example)

Next, the present invention will be described in more detail by examples, but the present invention is not limited at all by these examples.

〔Cathion charge density〕

Deionized water was added and dissolved using a measuring cylinder so that the sample concentration was 0.005% (w/v). Using hydrochloric acid (HCl) or sodium hydroxide (NaOH) solution, the pH is adjusted to 4, and the polyvinyl sulfate solution is added dropwise until the color of the toluidine blue indicator changes, and from an appropriate amount. The cation charge density was calculated.

〔Intrinsic viscosity (η)〕

Using a Canon-Penske type viscometer (manufactured by Kusano Science Instrument Mill Co., Ltd., No.75), the flow time was measured at 30°C, and the measured value It was calculated using the equation of Huggins and Mead-Fuoss.

The cationic polyacrylamide can be synthesized by a known polymerization method, and is synthesized by, for example, an aqueous polymerization method, an emulsion polymerization method, or a suspension polymerization method. The polymerization examples shown below are only examples and do not limit the manufacturing method.

(Synthesis Example 1: Synthesis of cationic polyacrylamide (A))

In a 1 L flask equipped with a separator-type cooling jacket, 720 g of water, 71.5 g of acrylamide (AAm) (manufactured by FUJIFILM Wako Pure Chemical Corporation), and dimethylaminoethyl acrylate (DAA) were added. Add 8.5 g of quaternary salt (manufactured by Fujifilm Wako Junyaku Co., Ltd.) and 0.008 g of carbon tetrachloride (manufactured by Fujifilm Wako Junyaku Co., Ltd.) as a chain transfer agent. 0.005 g (manufactured by Co., Ltd.) was added and stirred. Then, when the temperature reached 60°C, the stirring was stopped and the temperature was kept for 4 hours. Then, it cooled and obtained the cationic polyacrylamide (A).

The cation charge density and intrinsic viscosity (η) of the obtained cationic polyacrylamide (A) were measured by the above method. Table 1 shows the results.

(Synthesis Examples 2 to 8: Preparation of cationic polyacrylamides (B to H))

Cationic polyacrylamides (B to H) of Synthesis Examples 2 to 8 were synthesized in the same manner as in Synthesis Example 1, except that the monomer ratio shown in Table 1 was changed. The cation charge density and intrinsic viscosity (η) of the obtained cationic polyacrylamides (B to H) were measured by the above method. Table 1 shows the results.

(Table 1)

The following measurements were performed on the sample solutions obtained in Examples and Comparative Examples. The results are shown in Table 2-1, Table 2-2, and Table 3.

〔Cathion requirement〕

The pulp slurry was filtered through a filter cloth having a 150 µm pass, and the filtrate was collected. The filtrate was put into a flow potentiometer (PCD (Particle Change Detector)-03 type, manufactured by Mutek), and a titration solution (Poly-DADMAC, Kishida Chemical Co., Ltd.) Ltd.) product), the cation requirement was measured.

〔Free quantity〕

As a tubular tester, an 80 mesh wire and a water drainage pipe are attached to the bottom of the tester, and water in the pulp sample accumulated in the tub falls down through the mesh wire by opening and closing the valve. The amount of free water at this time for 10 seconds was measured with a measuring cylinder.

In addition, compared to a blank to which cationic polyacrylamide is not added, the productivity is improved as the amount of free water increases.

〔yield〕

The filtrate was collected using a free water yield tester (DFS-03, manufactured by Mutech), and the suspended solid concentration (SS concentration) was measured, and the yield was calculated by the following equation.

In addition, compared to the blank to which the cationic polyacrylamide is not added, the higher the yield, the lower the white water concentration and the load on the wastewater treatment can be reduced. In addition, cost reduction can be achieved by saving raw materials.

Yield (%) = (1-SS concentration of filtrate / SS concentration of paper) × 100

〔Asset Yield〕

The suspended material of the filtrate collected by the Yeosu Yield Tester was burned at 600° C. for 6 hours in an electric furnace, and the remaining ash was measured, and the ash yield was calculated by the following equation.

In addition, compared to the blank to which the cationic polyacrylamide is not added, the higher the ash yield, the higher the yield effect of the fuel such as calcium carbonate is expected, so that the cost can be reduced by saving fuel.

Ash yield (%) = (1-ash concentration of filtrate / ash concentration of paper stock) × 100

[Turbidity]

Measurement was made using a portable turbidimeter (2100Q, manufactured by DKK-TOA CORPORATION).

In addition, as compared to a blank to which cationic polyacrylamide is not added, the lower the turbidity, the less contamination in the system, and thus the risk of defects and web breaks can be reduced.

[Test 1] Confirmation test at the laboratory level

(Example 1)

The stock was collected from the manufacturing plant of the central raw paper and used in the experiment (the required amount of cation (CD) is 395 μeq/L). 180 mL of the stock was taken into a container, and 0.005% by mass of a solution in which 0.1% by mass of the cationic polyacrylamide (B) obtained in Synthesis Example 2 was dissolved was added, followed by stirring at 800 rpm for 20 seconds to prepare a sample solution.

(Examples 2 to 15, Comparative Examples 1 to 16)

Sample solution in the same manner as in Example 1, except that the cationic polyacrylamide (B) was changed to the cationic polyacrylamide shown in Table 2-1, and added in the blending amount shown in Table 2-1. Was prepared.

(Examples 16 to 27, Comparative Examples 17 to 25)

The cationic polyacrylamide (B) was changed to the cationic polyacrylamide shown in Table 2-2, and added in the blending amount shown in Table 2-2, and also aluminum sulfate and Zetaace as an organic coagulant. ) Sample solution in the same manner as in Example 1, except that S701 (manufactured by Kurita Water Industries Ltd.) and PAC (polyaluminum chloride) were added in the amount shown in Table 2-2. Was prepared.

(Example 28)

Calcium carbonate (manufactured by Shiraishi Kogyo Kaisha, Ltd.) as a fuel was added to LBKP (CD = 230 μeq/L) containing 25% by mass of coated broke to be 15% by mass. The stock was adjusted. 180 mL of the stock was taken into a container, 0.01% by mass of the cationic polyacrylamide (E) obtained in Synthesis Example 5 was added thereto, followed by stirring at 800 rpm for 20 seconds to prepare a sample solution.

(Example 29, Comparative Examples 26 to 28)

Sample solution in the same manner as in Example 28, except that the cationic polyacrylamide (E) was changed to the cationic polyacrylamide shown in Table 2-2 and added in the blending amount shown in Table 2-2. Was prepared.

(Table 2-1)

(Table 2-2)

For papers with high cation requirements (100 μeq/L or more), a specific amount of cationic polyacrylamide having a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g is added. It can be seen that in all of Examples 1 to 29, the amount of free water was large, the turbidity was low, and the yield was improved compared to the blank to which the cationic polyacrylamide was not added. In addition, in all of Examples 1 to 29, the cationic polyacrylamide having a greater amount of free water and a cation charge density exceeding 1000 μeq/g compared to the comparative example to which the cationic polyacrylamide having a cation charge density of less than 200 μeq/g was added It can be seen that the turbidity is low and the yield is improved as compared to the comparative example to which is added.

[Test 2] Test at the actual level

(Example 30)

In the manufacturing process of paper and cardboard shown in Fig. 1, 180 mL of the stock (CD = 400 µeq/L) before being supplied from the pump 35 to the screen 36 (VII) was collected in a container. 0.01% by mass of the cationic polyacrylamide (E) obtained in Synthesis Example 5 was added thereto, followed by stirring at 800 rpm for 20 seconds to prepare a sample solution.

(Example 31, Comparative Examples 29 to 31)

A sample solution was prepared in the same manner as in Example 30, except that the cationic polyacrylamide (E) was changed to the cationic polyacrylamide shown in Table 3 and added in the blending amount shown in Table 3.

(Table 3)

For water quality with high cation requirements (100 μeq/L or more), a specific amount of cationic polyacrylamide having a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g is added. In all of Examples 30 and 31, it was found that compared to Comparative Examples 30 and 31 in which cationic polyacrylamide having a cation charge density exceeding 1000 μeq/g was added, the amount of free water was large, the turbidity was low, and the yield was improved I can. In addition, the ash yield is also improved, and a reduction in the amount of fuel used can be expected.

(Industrial availability)

In the method of manufacturing paper and cardboard of the present invention, even when a large amount of anionic trash is contained in white water in the papermaking process, the amount of free water can be increased, the yield can be improved, and the turbidity can be reduced.

10: paper making system
20: raw material system
21: first raw material tank
22: second raw material tank
23: Mixing Chest
24: Machine Chest
25: seed box
30: composition and grassland
31: Unemployed Silo
32, 35: pump
33: cleaner
34: regulator
36: screen
37: inlet
38: wire part
39: Unemployed
40: recovery system
41: white water recovery device
42: recovery water tank

Claims (4)

It is equipped with a papermaking process that uses a paper stock with a cation requirement of 100 μeq/L or more as a papermaking fee,
Cationic polyacrylamide having a cation charge density of 200 to 1000 μeq/g and an intrinsic viscosity (η) of 2.7 to 18.3 dL/g is added to the stock in a range of 0.005 to 0.1 mass% based on the solids of the stock doing
Method of manufacturing paper and cardboard.
The method of claim 1,
The paper stock is a papermaking material including mechanical pulp
Method of manufacturing paper and cardboard.
The method of claim 1,
The paper material is a papermaking material containing 30% by mass or more of deinking pulp
Method of manufacturing paper and cardboard.
The method of claim 1,
The paper material is a papermaking material containing 30% by mass or more of used paper pulp.
Method of manufacturing paper and cardboard.

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