JP6929899B2 - Manufacturing method of paper and paper board - Google Patents

Description

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

Currently, papermaking is carried out by going through a papermaking process of making a raw material slurry in which a pulp raw material is dispersed in water. In the papermaking 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 the papermaking raw materials. In particular, due to the improvement in the mixing ratio of deinked pulp, mechanical pulp, and used paper contained in papermaking raw materials and the reuse of white water, anion trash tends to accumulate in the paper manufacturing process, resulting in a decrease in yield and raw materials for paper. When a paper layer is formed on the wire, the fibers, fillers, and other additives are prevented from flowing out of the wire and into white water.

For example, in Patent Document 1, 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 the specific water-soluble polymer (B) is used. Is described, and a method for suppressing the occurrence of paper defects due to an impairing substance such as anion trash, micropitch, and turbidity component is described, which comprises adding a yield improving agent as appropriate to make paper. 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 turbidity components are fixed to the pulp fiber, resulting in unfixed micropitch and unfixed micropitch and. It prevents the turbidity component from agglomerating.

JP-A-2009-249756

As a water quality index, when the cation requirement is 100 μeq / L or more (for example, the measured value of a PCD measuring device manufactured by Mutec), the anion trash increases. When various cationic polymers such as a coagulant, a retention agent, and a paper strength agent are added in a large amount in order to neutralize the charge of a large amount of anion trash, a large amount of anion trash aggregated in a strong cation is agglomerated and papermaking is performed. In the process, it becomes easy to adhere to tools and equipment, and problems often occur that make the situation worse. Further, even 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, the amount of filtered water is increased, the yield rate is improved, and the turbidity is reduced. It is an object of the present invention to provide a method for producing paper and a paper board capable of producing paper and paper board.

As a result of diligent research, the present inventors have found that the problem can be solved by adding a specific amount of a specific low-cationic polyacrylamide to the total solid content of the paper material.
The present invention has been completed based on such findings.

That is, the disclosure of the present application relates to the following.
[1] A cation having a papermaking process using a paper material 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 a paper board, in which sex polyacrylamide is added to the paper material in the range of 0.005 to 0.1% by mass with respect to the solid content of the total paper material.
[2] The method for producing a paper and a paper board according to the above [1], wherein the paper material is a papermaking raw material containing mechanical pulp.
[3] The method for producing paper and paper board according to the above [1], wherein the paper material is a papermaking raw material containing 30% by mass or more of deinked pulp.
[4] The method for producing paper and paper board according to the above [1], wherein the paper material is a papermaking raw material containing 30% by mass or more of used paper pulp.

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

It is a block diagram which shows the manufacturing method of the paper and the paper board which concerns on one Embodiment of this invention.

The method for producing paper and paper board according to the embodiment of the present invention (hereinafter, may be referred to as "the present embodiment") involves a papermaking process using a paper material having a cation requirement of 100 μeq / L or more as a papermaking raw material. 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 0.005 to 0.1% by mass based on the total solid content of the paper material. It is characterized by being added to the paper material in a range.
When a paper material having a cation requirement of 100 μeq / L or more is used as a papermaking raw material, a large amount of anion trash is contained in the white water in the papermaking process. On the other hand, in the present 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 paper. As a result, it is possible to suppress the agglomeration of the anion trash, thereby increasing the amount of filtered water, improving the yield rate, and reducing the turbidity.

The cationic polyacrylamide used in the method for producing paper and paper board according to the present embodiment has a cationic charge density of 200 to 1000 μeq / g. Here, the cationic charge density means the equivalent number (μeq / g) of the cationic charge in the monomer unit constituting the polymer.
If the cation charge density is less than 200 μeq / g, the amount of filtered water may decrease, and if it exceeds 1000 μeq / g, the effect of reducing turbidity may not be obtained. From this point of view, the cationic charge density is preferably 200 to 700 μeq / g, more preferably 200 to 300 μeq / g.
The cationic charge density can be determined by the method described in Examples.

The intrinsic viscosity η of the cationic polyacrylamide is 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. Further, 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 the effect of increasing the amount of filtered water may not be sufficiently exhibited. From this point of view, the intrinsic viscosity η is preferably 9 to 18 dL / g, more preferably 13 to 18 dL / g.
The intrinsic viscosity η is calculated by measuring the flow time at 30 ° C. using a Canon Fenceke type viscometer and using the Huggins formula and the Made-Fooss formula from the measured values.

The cationic polyacrylamide is not particularly limited as long as the cationic charge density and the intrinsic viscosity η are within the above ranges, and for example, the acrylamide monomer and the cationic monomer are subjected to an aqueous polymerization method, an emulsion polymerization method, or a suspension polymerization method. It can be obtained by a known polymerization method such as. The charge density is adjusted by the mixing ratio of the monomers 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) acrylic acid ester derivatives such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate; (meth) such as dimethylaminopropyl (meth) acrylamide and diethylaminopropyl (meth) acrylamide. ) Acrylamide derivatives; quaternary salts and acid salts of dimethylaminoethyl (meth) acrylates; tertiary amino monomers and tertiary amine monomers such as allylamine and diallylamine, and quaternary salts and acid salts thereof. Of these, a quaternary salt of dimethylaminoethyl (meth) acrylate is preferably used.
As these cationic monomers, one kind or two or more kinds can be used.

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

The polymerization initiator used in producing the cationic polyacrylamide is not particularly limited, and is, for example, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, benzoyl peroxide, and tert-butyl peroxide. And so on. One kind or two or more kinds of polymerization initiators can be used.

It is also preferable to use a chain transfer agent to adjust the viscosity of the cationic polyacrylamide to be synthesized. The chain transfer agent is not particularly limited, and examples thereof include chlorine tetrachloride, chloroform, carbon tetrachloride and the like. One type or two or more types of chain transfer agents can be used.

FIG. 1 is a block diagram showing 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 system, a papermaking system 30, and a recovery system 40.
The raw material system 20 produces pulp from a paper raw material. The raw material system 20 in the present embodiment has a raw material tank (1) 21 and a raw material tank (2) 22. In the raw material tank (1) 21, chemical pulp such as broad-leaved bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), broad-leaved unbleached kraft pulp (LUKP) and coniferous unbleached kraft pulp (NUKP); Mechanical pulp such as GP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP) and refiner mechanical pulp (RMP) is housed, and the raw material tank (2) 22 contains corrugated waste paper pulp and liner waste paper pulp. , Magazine used paper pulp, newspaper used paper pulp, ground ticket used paper pulp, upper white used paper pulp, deinked used paper pulp, and other used paper pulp are stored.

The pulp contained in the raw material tank (1) 21 and the raw material tank (2) 22 is supplied to the mixing chest 23 in an appropriate ratio and mixed in the mixing chest 23. The mixed pulp is transferred to the seed box 25 after a paper-making chemical such as a viscous agent is added in the 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 papermaking system 30 prepares pulp and makes paper. The pulp contained 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. Further, it is supplied to the screen 36 by the pump 35, where foreign matter is removed, and then supplied to the inlet 37. The inlet 37 suppresses flock and flow fringes by supplying pulp to the wire of the wire part 38 at an appropriate concentration, speed, and angle. The supplied pulp is dehydrated with water in a wire part 38 and a press part (not shown), then dried in a dryer part (not shown), and then appropriately treated 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 material pulp normally used for papermaking, other paper-making chemicals, and the like.
The white water 39 separated by the wire part 38 is stored in the white water silo 31. A 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 papermaking system 30 of the present embodiment.

The recovery system 40 collects white water from the preparation and papermaking system 30. The supplied white water is transferred to the white water recovery device 41, filtered by the white water recovery device 41, and solid-liquid separated. The solid content is transferred to the machine chest 24, and the filtrate is collected and stored in the reclaimed water tank 42. A part of the filtrate is further filtered and used as adjusting water for adjusting the concentration of white water discharged to the outside or circulated.
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 adjusting water may contain a small amount of a paper-making agent as long as the effects of the present invention are not impaired.
The chemicals for paper making are not particularly limited, and for example, surfactants, waxes, sizing agents, fillers, rust preventives, conductive agents, defoaming agents, slime control agents, dispersants, viscosity modifiers, coagulants, and coagulation agents. Examples thereof include agents, paper strength enhancers, yield improvers, paper dust dropout preventives and bulky agents.

The above-mentioned addition of cationic polyacrylamide to the paper material (pulp) is a supply line of the pulp from the mixing chest 23 to the machine chest 24 or a machine chest 24 (I), a transfer line from the machine chest 24 to the seed box 25. Alternatively, 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), and 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. Line or inlet 37 (VIII), transfer line of white water to white water silo 31 separated by wire part 38 (IX), transfer line of white water from white water silo 31 to white water recovery device 41 or white water recovery device 41 (X) Can be done. Above all, from the viewpoint of suppressing the agglomeration of anion trash, the addition of cationic polyacrylamide is preferably any of the above (IV), (V), (VI), (VII), and (VIII). Any of (VI), (VII), and (VIII) is more preferred.

In the method for producing paper and paper board of the present embodiment, the agglomeration of anion trash can be suppressed by adding cationic polyacrylamide. Therefore, as a paper material, a papermaking raw material containing mechanical pulp and deinked pulp A papermaking raw material containing 30% by mass or more of waste paper pulp and a papermaking raw material containing 30% by mass or more of used paper pulp can be used.

The amount of the cationic polyacrylamide added is 0.005 to 0.1% by mass with respect to the total solid content of the paper material. If it is less than 0.005% by mass, the coagulation effect is low and the yield / drainage effect cannot be sufficiently exhibited. Further, if it exceeds 0.1% by mass, the agglutination effect is too strong, which may affect the quality of the product. From this point of view, the amount of cationic polyacrylamide 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 paper material.

Next, the present invention will be described in more detail by way of 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 became 0.005% (w / v). Adjust the pH to 4 with hydrochloric acid (HCl) or sodium hydroxide (NaOH) solution, add a solution of potassium polyvinyl sulfate until the color of the toluidiline blue indicator changes, and add cations from the titration. The charge density was calculated.

[Intrinsic viscosity η]
The flow time was measured at 30 ° C. using a Canon Fenceke type viscometer (No. 75 manufactured by Kusano Kagaku Kikai Seisakusho Co., Ltd.), and calculated from the measured values using the Huggins formula and the Made-Foss formula. bottom.

The cationic acrylamide can be synthesized by a known polymerization method, for example, it is synthesized by an aqueous polymerization method, an emulsion polymerization method, or a suspension polymerization method. The polymerization examples shown below are only examples thereof, and do not limit the production method.
(Synthesis Example 1: Synthesis of Cationic Polyacrylamide A)
In a 1 L flask 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 Industries, Ltd. 8.5 g (manufactured by Fuji Film Co., Ltd.) and 0.008 g of carbon tetrachloride (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) as a chain transfer agent are added, and when the temperature reaches 50 ° C., the initiator (Fuji Film Wako Pure Chemical Industries, Ltd. (Fuji Film Wako Pure Chemical Industries, Ltd.) (Manufactured by Wako Pure Chemical Industries, Ltd.) 0.005 g was added and stirred. Then, when the temperature reached 60 ° C., stirring was stopped and the temperature was kept warm for 4 hours. Then, it cooled and obtained cationic polyacrylamide A.
The cationic charge density and intrinsic viscosity η of the obtained cationic polyacrylamide A were measured by the above-mentioned method. The results are shown in Table 1.

(Synthesis Examples 2-8: 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 ratios were changed to those shown in Table 1. The cationic charge densities and intrinsic viscosities η of the obtained cationic polyacrylamides B to H were measured by the above-mentioned methods. The results are shown in 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 and Table 2-2 and Table 3.

[Cation requirement]
The pulp slurry was filtered through a 150 μm pass filter cloth, and the filtrate was collected. The filtrate was put into a flow electrometer (PCD (Particle Change Detector) -03, manufactured by Mutec), and the cation requirement was measured from the amount of titrant (Poly-DADMAC, manufactured by Kishida Chemical Co., Ltd.). ..

[Amount of drainage]
Using a tubular tester with an 80 mesh wire at the bottom and a drainage tester with a pipe through which water can escape, the water in the pulp sample accumulated in the cylinder drops down through the mesh wire when the valve is opened and closed. The amount of filtered water for 10 seconds at this time was measured with a measuring cylinder.
The productivity is improved as the amount of filtered water is larger than that of the blank to which the cationic polyacrylamide is not added.

[Yield rate]
A filtrate was collected using a drainage yield tester (DFS-03, manufactured by Mutec), the suspended solid content concentration (SS concentration) was measured, and the yield rate was calculated by the following formula.
As compared with the blank to which cationic polyacrylamide is not added, the higher the yield rate, the more the white water concentration can be reduced and the load of wastewater treatment can be reduced. In addition, it is possible to reduce costs by saving raw materials.
Yield rate (%) = (1-SS concentration of filtrate / SS concentration of paper) x 100

[Ash yield rate]
The suspended solids of the filtrate collected by the filtered water yield tester were baked at 600 ° C. for 6 hours in an electric furnace, the remaining ash content was measured, and the ash content yield rate was calculated from the following formula.
As compared with the blank to which cationic polyacrylamide is not added, the higher the ash yield rate, the more the yield effect of the filler such as calcium carbonate is expected, so that the cost can be reduced by saving the filler.
Ash yield rate (%) = (1-ash concentration of filtrate / ash concentration of paper material) x 100

[Turbidity]
It was measured using a portable turbidity meter (2100Q, manufactured by DKK-TOA CORPORATION).
As compared with the blank to which cationic polyacrylamide is not added, the lower the turbidity, the less the stain in the system, and the risk of defects and paper breakage can be reduced.

[Test 1] Confirmation test at the laboratory level (Example 1)
The paper material collected from the core base paper manufacturing plant was used in the experiment (cation requirement (CD) was 395 μeq / L). 180 mL of paper material was taken in a container, 0.005% by mass of a solution of cationic polyacrylamide B obtained in Synthesis Example 2 dissolved in 0.1% by mass was added thereto, and the sample solution was stirred at 800 rpm for 20 seconds. Prepared.

(Examples 4, 7, 10, 13, Reference Examples 1 to 11 , Comparative Examples 1 to 16)
A sample solution 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 blending amount shown in Table 2-1.

(Example 16,19,22,25, Reference Examples 12-19, Comparative Examples 17-25)
Cationic polyacrylamide B was changed to the cationic polyacrylamide shown in Table 2-2 and added in the blending amounts shown in Table 2-2, and further, as a sulfate band and an organic coagulant, Zeta Ace S701 (Kurita Kogyo (Kurita Kogyo) A sample solution was prepared in the same manner as in Example 1 except that (manufactured by Co., Ltd.) and PAC (polyaluminum chloride) were added in the blending amounts shown in Table 2-2.

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

( Reference Example 21 , Comparative Examples 26 to 28)
A sample solution was prepared in the same manner as in Reference Example 20 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.

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 was added to a paper material having a high cation requirement (100 μeq / L or more). In Examples 4, 7, 10, 13, 16, 19, 22, and 25, the amount of filtered water is large, the turbidity is low, and the yield rate is improved as compared with the blank to which the cationic polyacrylamide is not added. You can see that there is. Further, in Examples 4, 7, 10, 13, 16, 19, 22, and 25, the amount of drained water was larger than that in Comparative Example in which cationic polyacrylamide having a cationic charge density of less than 200 μeq / g was added. It can be seen that the turbidity is low and the yield rate is improved as compared with the comparative example in which the cationic polyacrylamide having a cationic charge density of more than 1000 μeq / g is added.

[Test 2] Test at the actual machine level ( Reference Example 22 )
In the process of manufacturing the paper and the paper plate shown in FIG. 1, 180 mL of the paper material (CD = 400 μeq / L) before being supplied from the pump 35 to the screen 36 was collected 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.

( Reference Example 23 , Comparative Examples 29 to 31)
A sample solution was prepared in the same manner as in Reference Example 22 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.

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 was added to water quality having a high cation requirement (100 μeq / L or more). In Reference Examples 22 and 23 , the amount of filtered water is large, the turbidity is low, and the yield rate is improved as compared with Comparative Examples 30 and 31 in which cationic polyacrylamide having a cationic charge density exceeding 1000 μeq / g is added. You can see that there is. In addition, the ash yield rate has also improved, and it is expected that the amount of filler used will be reduced.

The method for producing paper and paper board of the present invention can increase the amount of filtered water, improve the yield rate, and reduce the turbidity even when the white water contains a large amount of anion trash in the 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 silo 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: Recovery water tank

Claims (4)

A papermaking process using a paper material having a cation requirement of 100 μeq / L or more as a papermaking raw material, a cationic polyacrylamide having a cation charge density of 200 to 300 μeq / g and an intrinsic viscosity η of 13 to 18.3 dL / g. A method for producing paper and a paper board, which is added to the paper material in the range of 0.01 to 0.08% by mass with respect to the solid content of the total paper material. The method for producing paper and a paper board according to claim 1, wherein the paper material is a papermaking raw material containing mechanical pulp. The method for producing paper and a paper board according to claim 1, wherein the paper material is a papermaking raw material containing 30% by mass or more of deinked pulp. The method for producing paper and a paper board according to claim 1, wherein the paper material is a papermaking raw material containing 30% by mass or more of used paper pulp.

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