JP2019218674A - Manufacturing method of paper and paper board - Google Patents

Abstract

To provide a manufacturing method of a paper and a paper board, capable of increasing filtrate amount, improving its yield, and reducing turbidity even when much of an anion trash is involved in a white water in a papermaking process.SOLUTION: The manufacturing method of a paper and a paper board includes a papermaking process where a paper stock having a cation demand of 100 μeq/L or over is used as a raw paper for papermaking, wherein a cationic polyacrylamide having a cation charge density of 200-1000 μeq/g and an intrinsic viscosity η of 2.7-18.3dL/g is added to the paper stock in a range of 0.005-0.1 mass% to the total paper stock solid content.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing paper and paperboard.

At present, papermaking is carried out through a papermaking process of making a raw material slurry in which a pulp raw material is dispersed in water. In the paper making process, a large amount of white water containing fine fibers and filler is discharged from a paper machine or the like. The discharged white water is circulated and used in the papermaking process from the viewpoint of effective utilization and reuse of water resources.
Various anionic substances such as resins, sizing agents, fluorescent dyes and latex are contained in papermaking raw materials. In particular, due to the improvement in the blending ratio of deinked pulp, mechanical pulp, and used paper contained in papermaking raw materials, and the reuse of white water, anion trash is likely to accumulate in the paper manufacturing process, lowering the yield and reducing paper raw materials. When fibers, fillers and other additives are formed on the wire in a paper layer, there is an obstacle to pass through the wire and flow into white water.

  For example, in Patent Document 1, after a specific water-soluble polymer (A) is added to a papermaking raw material before dilution with white water, the papermaking raw material is diluted with white water, and then a specific water-soluble polymer (B) is added. And a method for suppressing the generation of paper defects by an obstacle-acting substance such as an anion trash, a micropitch, or a turbidity component. In this method, by adding a specific water-soluble polymer to the papermaking raw material, the charge of the anion trash is neutralized, and the micropitch and the turbidity component are fixed to the pulp fiber. It prevents turbidity components from agglomerating.

JP 2009-249756 A

  As the water quality index, when the required cation amount is 100 μeq / L or more (for example, a value measured by a PCD measuring device manufactured by Mutech Co., Ltd.), an anion trash increases. When a large amount of various cationic polymers such as coagulant, retention agent, paper strength agent, etc. are added to neutralize the charge of a large amount of anion trash, a large amount of anion trash agglomerated by strong cations is agglomerated and papermaking is performed. In the process, it tends to adhere to tools and equipment, and the problem that the situation worsens often occurs. Also, in the method described in Patent Document 1, a sufficient effect cannot be obtained when the amount of anion trash is large.

  The present invention has been made in view of such circumstances, and even when a large amount of anion trash is contained in white water in the papermaking process, it is possible to increase the drainage amount, improve the yield, and reduce turbidity. It is an object of the present invention to provide a method for producing paper and a paper board that can be used.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that the problems can be solved by adding a specific low-cationic polyacrylamide in a specific amount to the total solid content of the stock.
The present invention has been completed based on such findings.

That is, the present disclosure relates to the following.
[1] A cation having a papermaking process using a stock having a cation requirement of 100 μeq / L or more as a papermaking raw material, 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 paperboard, comprising adding a reactive polyacrylamide to a stock in the range of 0.005 to 0.1% by mass based on the total solid content of the stock.
[2] The method for producing paper and paperboard according to the above [1], wherein the stock is a papermaking raw material containing mechanical pulp.
[3] The method for producing paper and paperboard as described in [1] above, wherein the stock is a papermaking raw material containing 30% by mass or more of deinked pulp.
[4] The method for producing paper and paperboard according to the above [1], wherein the stock is a papermaking raw material containing 30% by mass or more of waste paper pulp.

  According to the present invention, even when white water contains a large amount of anionic trash in the papermaking process, a method for producing paper and a paper board capable of increasing the drainage amount, improving the yield, and reducing the turbidity is provided. be able to.

It is a block diagram showing a paper and paperboard manufacturing method concerning one embodiment of the present invention.

The method for manufacturing paper and paperboard according to the embodiment of the present invention (hereinafter, may be referred to as “the present embodiment”) includes a papermaking process using a stock having a cation requirement of 100 μeq / L or more as a raw material for papermaking. A 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 in an amount of 0.005 to 0.1% by mass with respect to the total solid content of the stock. It is characterized in that it is added to the stock within a range.
When a paper material having a cation requirement of 100 μeq / L or more is used as a papermaking raw material, white water contains a large amount of anionic trash in the papermaking process. On the other hand, in this embodiment, a specific amount of cationic polyacrylamide having a cationic 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 total solid content of the stock. This can suppress agglomeration of the anion trash, thereby increasing the amount of drainage, improving the yield, and reducing the turbidity.

The cationic polyacrylamide used in the paper and paperboard manufacturing method according to the present embodiment has a cationic charge density of 200 to 1000 μeq / g. Here, the cationic charge density refers to the equivalent number (μeq / g) of the cationic charge in the monomer unit constituting the polymer.
If the cationic charge density is less than 200 μeq / g, the amount of drainage may decrease, and if it exceeds 1000 μeq / g, the effect of reducing turbidity may not be obtained. From such a viewpoint, the cationic charge density is preferably from 200 to 700 μeq / g, and more preferably from 200 to 300 μeq / g.
The cationic charge density can be determined 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, the molecular weight of the cationic polyacrylamide is too small, so that the range in which the agglutination reaction can occur is narrow, and a sufficient yield effect may not be obtained. On the other hand, if 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 the effect of increasing the amount of drainage may not be sufficiently exhibited. From such a viewpoint, the intrinsic viscosity η is preferably 9 to 18 dL / g, more preferably 13 to 18 dL / g.
The intrinsic viscosity η is measured by measuring the flow time at 30 ° C. using a Cannon-Fenske viscometer, and is calculated from the measured value using the Huggins equation and the Mead-Fooss equation.

The cationic polyacrylamide is not particularly limited as long as the cationic charge density and the intrinsic viscosity η are within the above ranges, for example, an aqueous polymerization method, an emulsion polymerization method, and a suspension polymerization method of an acrylamide monomer and a cationic monomer. And other known polymerization methods. The charge density is adjusted by the proportion of the monomer used, and the intrinsic viscosity is adjusted by the polymerization temperature, the monomer concentration, and the amount of the initiator added.
Examples of the cationic monomer include (meth) acrylate derivatives such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; and (meth) acrylates such as dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide. ) Acrylamide derivatives; quaternary salts and acid salts of dimethylaminoethyl (meth) acrylate; tertiary amino monomers and tertiary amine monomers such as allylamine and diallylamine; and quaternary salts and acid salts thereof. Among them, a quaternary salt of dimethylaminoethyl (meth) acrylate is preferably used.
One or more of these cationic monomers can be used.

The compounding ratio of the cationic monomer to the total amount of the monomers from which all the structural units of the cationic polyacrylamide are derived is preferably 0.5 to 9.5 mol%, more preferably 1 to 8 mol%. By setting the proportion of the cationic monomer within the above range, the cationic charge density of the cationic polyacrylamide can be within the above range.
Further, the blending ratio of the acrylamide monomer to the total amount of the monomers from which all the structural units of the cationic polyacrylamide is derived is preferably 90.5 to 99.5 mol%, more preferably 92 to 99 mol%.

  The polymerization initiator used when producing the cationic polyacrylamide is not particularly limited, for example, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, and tert-butyl peroxide And the like. One or more polymerization initiators can be used.

  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 more chain transfer agents can be used.

FIG. 1 is a block diagram illustrating a method for manufacturing paper and a paper board according to an embodiment of the present invention.
The papermaking system 10 includes a raw material system 20, a preparation, a papermaking system 30, and a collection system 40.
The raw material system 20 produces pulp from paper raw materials. The raw material system 20 in the present embodiment has a raw material tank (1) 21 and a raw material tank (2) 22. The raw material tank (1) 21 contains chemical pulp such as hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP) and softwood unbleached kraft pulp (NUKP); GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and refiner mechanical pulp (RMP). The raw material tank (2) 22 contains corrugated paper pulp and liner waste pulp. And used paper pulp such as used magazine pulp, used newspaper pulp, ground ticket used paper pulp, Kamishira used paper pulp, and deinked used paper pulp.

The pulp stored in the raw material tank (1) 21 and the raw material tank (2) 22 is supplied to a mixing chest 23 at an appropriate ratio, and is mixed by the mixing chest 23. The mixed pulp is transferred to a seed box 25 after a papermaking chemical such as a sticky agent is added thereto in a machine chest 24.
The raw material tank (1) 21, the raw material tank (2) 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 preparation and paper making system 30 prepares pulp and makes paper. The pulp stored in the seed box 25 is supplied to the white water silo 31, and then supplied sequentially to the cleaner 33 by the pump 32. Further, it is supplied to a screen 36 by a pump 35, where foreign matter is removed therefrom, and then supplied to an inlet 37. The inlet 37 suppresses flocs and flow streaks by supplying pulp to the wire of the wire part 38 at an appropriate concentration, speed, and angle. The supplied pulp is dehydrated in water by a wire part 38 and a press part (not shown), then dried by a dryer part (not shown), and is appropriately processed to produce paper.

Here, the liquid separated by the wire part 38 is white water 39. The white water 39 contains fine fibers derived from the raw pulp usually used in papermaking, other chemicals for papermaking, and the like.
The white water 39 separated by the wire part 38 is stored in the white water silo 31. Part of the white water stored in the white water silo 31 is supplied to the pump 32, and the rest is supplied to the white water recovery device 41.
The white water silo 31 to the wire part 38 constitute the preparation and paper making system 30 of the present embodiment.

The recovery system 40 recovers white water from the preparation and papermaking 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 be separated into solid and liquid. The solid content is transferred to the machine chest 24, and the filtrate is collected and stored in a collected water tank 42. A part of the filtrate is further filtered and discharged to the outside, or used as adjusted water for adjusting the concentration of circulating white water.
The white water recovery device 41 and the recovered water tank 42 constitute a recovery system 40 of the present embodiment.

The white water and the conditioned water may contain a small amount of a papermaking agent as long as the effects of the present invention are not impaired.
The papermaking agent is not particularly limited and includes, for example, a surfactant, a wax, a sizing agent, a filler, a rust inhibitor, a conductive agent, an antifoaming agent, a slime control agent, a dispersant, a viscosity modifier, a flocculant, and a coagulant. Agents, paper strength enhancers, retention enhancers, paper powder fall-off inhibitors, bulking agents and the like.

  The above-mentioned addition of the cationic polyacrylamide to the stock (pulp) is performed by supplying the pulp with a supply line from the mixing chest 23 to the machine chest 24 or a transfer line from the machine chest 24 (I) or the machine chest 24 to the seed box 25. Or the seed box 25 (II), the supply line from the seed box 25 to the white water silo 31 or the white water silo 31 (III), the supply line from the white water silo 31 to the pump 32 or the pump 32 (IV), or the pump 32 to the cleaner 33. Supply line or cleaner 33 (V), supply line or pump 35 (VI) from cleaner 33 to pump 35, supply line or screen 36 (VII) from pump 35 to screen 36, supply from screen 36 to inlet 37. In line or inlet 37 (VIII), wire part 38 Transfer line to the white water silo 31 white water that has been released (IX), can be carried out in the transfer line or the white water recovery device 41 from the white water silo 31 whitewater to white water recovery device 41 (X). Among them, from the viewpoint of suppressing agglomeration of the anionic trash, the addition of the cationic polyacrylamide is preferably any one of the above (IV), (V), (VI), (VII), and (VIII), and Any of (VI), (VII) and (VIII) is more preferred.

  In the method for producing paper and paper board of the present embodiment, since the agglomeration of anionic trash can be suppressed by adding cationic polyacrylamide, papermaking raw materials including mechanical pulp, deinked pulp And a papermaking raw material containing 30% by mass or more of waste paper pulp.

  The cationic polyacrylamide is added in an amount of 0.005 to 0.1% by mass based on the total solid content of the stock. If the content is less than 0.005% by mass, the coagulation effect is low, and the yield and drainage effects cannot be sufficiently exhibited. On the other hand, if the content exceeds 0.1% by mass, the coagulation effect is too strong, which may affect the quality of the product. From such a viewpoint, the amount of the cationic polyacrylamide to be added is preferably 0.01 to 0.08% by mass, more preferably 0.02 to 0.06% by mass, based on the total solid content of the stock.

  Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

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

[Intrinsic viscosity η]
Using a Canon Fenske viscometer (No. 75, manufactured by Kusano Kagaku Kikai Seisakusho Co., Ltd.), the flow time was measured at 30 ° C., and from the measured values, calculated using the Huggins equation and the Mead-Fooss equation. did.

The cationic acrylamide can be synthesized by a known polymerization method, for example, by 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 production 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 Fuji Film Wako Pure Chemical Industries, Ltd.), and a quaternary salt of dimethylaminoethyl acrylate (DAA) (Fuji Film Wako Pure Chemical ( 8.5 g) and carbon tetrachloride (manufactured by Fuji Film Wako Pure Chemical Co., Ltd.) 0.008 g as a chain transfer agent, and when the temperature reaches 50 ° C., an initiator (Fuji Film Wako Pure Chemical ( 0.005 g) was added and stirred. Next, when the temperature reached 60 ° C., stirring was stopped and the temperature was kept for 4 hours. Thereafter, the mixture was cooled to obtain cationic polyacrylamide A.
The cationic charge density and the intrinsic viscosity η of the obtained cationic polyacrylamide A were measured by the above-mentioned methods. Table 1 shows the results.

(Synthesis Examples 2 to 8: Production 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 was changed as shown in Table 1. The cationic charge densities and intrinsic viscosities η of the resulting cationic polyacrylamides B to H were measured by the methods described above. Table 1 shows the results.

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

[Cation demand]
The pulp slurry was filtered with a filter cloth having a pass of 150 μm, and the filtrate was collected. The filtrate was put into a streaming potentiometer (PCD (Particle Change Detector) -03, manufactured by Mutech Co., Ltd.), and the required amount of cation was measured from the amount of the titrant (Poly-DADMAC, manufactured by Kishida Chemical Co., Ltd.). .

(Drainage)
The water in the pulp sample accumulated in the cylinder falls down through the mesh wire by opening and closing the valve by using a drainage tester provided with an 80-mesh wire and a tube through which water comes out at the bottom with a cylindrical testing machine. At this time, the amount of drainage for 10 seconds was measured with a measuring cylinder.
In addition, as compared with a blank to which cationic polyacrylamide is not added, the higher the drainage amount, the higher the productivity.

[Yield rate]
The filtrate was collected using a drainage retention tester (DFS-03, manufactured by Mutech Co., Ltd.), the suspended solids concentration (SS concentration) was measured, and the yield was calculated by the following equation.
It should be noted that, as compared with a blank to which cationic polyacrylamide is not added, as the yield is higher, the concentration of white water can be reduced, and the load of wastewater treatment can be reduced. Further, cost can be reduced by saving raw materials.
Yield (%) = (1-SS concentration of filtrate / SS concentration of stock) × 100

[Ash yield rate]
The suspended matter of the filtrate collected by the drainage retention tester was baked at 600 ° C. for 6 hours in an electric furnace, the remaining ash was measured, and the ash retention was calculated from the following equation.
It should be noted that, as compared with a blank to which cationic polyacrylamide is not added, the higher the ash retention rate is, the more the effect of retaining filler such as calcium carbonate is expected, so that cost reduction can be achieved by saving filler.
Ash retention (%) = (1−ash concentration of filtrate / ash concentration of stock) × 100

(Turbidity)
The measurement was performed using a portable turbidity meter (2100Q, manufactured by Toa DKK Ltd.).
The lower the turbidity, the lower the turbidity in the system and the lower the risk of defects and paper breakage, as compared to a blank without the addition of cationic polyacrylamide.

[Test 1] Confirmation test at laboratory level (Example 1)
The stock used in the experiment was one collected from a core base paper manufacturing plant (cation demand (CD) was 395 μeq / L). 180 mL of the stock is taken in a container, and 0.005% by mass of a solution in which the cationic polyacrylamide B obtained in Synthesis Example 2 is dissolved in 0.1% by mass is added thereto. Prepared.

(Examples 2 to 15, Comparative Examples 1 to 16)
A sample liquid was prepared 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 amount shown in Table 2-1.

(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 amount shown in Table 2-2. Further, a sulfate band and Zetaace S701 (Kurita Kogyo Co., Ltd.) as an organic coagulant were added. Co., Ltd.) and PAC (polyaluminum chloride) were added in the same manner as in Example 1 except that they were added in the amounts shown in Table 2-2.

(Example 28)
The stock was adjusted by adding 15% by mass of calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd.) as a filler to LBKP (CD = 230 μeq / L) containing 25% by mass of the coated broke. 180 mL of the stock was taken in a container, 0.01% by mass of the cationic polyacrylamide E obtained in Synthesis Example 5 was added thereto, and the mixture was stirred at 800 rpm for 20 seconds to prepare a sample solution.

(Example 29, Comparative Examples 26 to 28)
A sample solution was prepared 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 was added in the amount shown in Table 2-2.

  A specific amount of cationic polyacrylamide having a cationic charge density of 200 to 1000 μeq / g and an intrinsic viscosity η of 2.7 to 18.3 dL / g is added to a paper material having a high cation demand (100 μeq / L or more). In each of Examples 1 to 29, it can be seen that the amount of drainage is larger, the turbidity is lower, and the yield is improved, as compared with blanks to which no cationic polyacrylamide is added. Further, in each of Examples 1 to 29, the amount of drainage was larger than that of Comparative Examples to which a cationic polyacrylamide having a cationic charge density of less than 200 μeq / g was added, and a cationic charge density of more than 1000 μeq / g was used. It can be seen that the turbidity is lower and the yield is improved as compared with the comparative example to which the hydrophilic polyacrylamide was added.

[Test 2] Test at Actual Machine Level (Example 30)
In the paper and paper board manufacturing process shown in FIG. 1, 180 mL of the stock (CD = 400 μeq / L) before (VII) supplied from the pump 35 to the screen 36 was collected in a container. To this, 0.01% by mass of the cationic polyacrylamide E obtained in Synthesis Example 5 was added and stirred at 800 rpm for 20 seconds to prepare a sample solution.

(Example 31, Comparative Examples 29 to 31)
A sample liquid 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 amount shown in Table 3.

  A specific amount of cationic polyacrylamide having a cationic charge density of 200 to 1000 μeq / g and an intrinsic viscosity of 2.7 to 18.3 dL / g was added to water having a high cation demand (100 μeq / L or more). Examples 30 and 31 both have higher drainage, lower turbidity, and improved yield compared to Comparative Examples 30 and 31 in which cationic polyacrylamide having a cationic charge density exceeding 1000 μeq / g was added. You can see that there is. Also, the ash yield rate has been improved, and a reduction in the amount of filler used can be expected.

  ADVANTAGE OF THE INVENTION The paper and paperboard manufacturing method of this invention can increase a drainage amount, improve a retention rate, and reduce turbidity, even when white water contains many anionic trash in a papermaking process.

10: Papermaking system 20: Raw material system 21: Raw material tank (1)
22: Raw material tank (2)
23: mixing chest 24: machine chest 25: seed box 30: preparation, papermaking system 31: white water silos 32, 35: pump 33: cleaner 34: regulator 36: screen 37: inlet 38: wire part 39: white water 40: recovery System 41: White water recovery device 42: Recovered water tank

(Examples 2 , 4, 5 , 7, 8 , 10, 11, 13, 14, Reference Examples 1 to 5 , Comparative Examples 1 to 16)
A sample liquid was prepared 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 amount shown in Table 2-1.

(Examples 16 , 17, 19, 20, 22, 23, 25 , 26, Reference Examples 6 to 9 , Comparative Examples 17 to 25)
The cationic polyacrylamide B was changed to the cationic polyacrylamide shown in Table 2-2 and added in the amount shown in Table 2-2. Further, a sulfate band and Zetaace S701 (Kurita Kogyo Co., Ltd.) as an organic coagulant were added. Co., Ltd.) and PAC (polyaluminum chloride) were added in the same manner as in Example 1 except that they were added in the amounts shown in Table 2-2.

Claims (4)

  A cationic polyacrylamide having a papermaking process using a stock having a cation requirement of 100 μeq / L or more as a papermaking raw material, a cationic 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 the range of 0.005 to 0.1% by mass based on the total solid content of the stock, and a method for producing paper and paperboard.   The method for producing paper and paperboard according to claim 1, wherein the stock is a papermaking raw material containing mechanical pulp.   The method according to claim 1, wherein the stock is a papermaking raw material containing 30% by mass or more of deinked pulp.   The method for producing paper and paperboard according to claim 1, wherein the stock is a papermaking raw material containing 30% by mass or more of waste paper pulp.