JP5262566B2 - Paper manufacturing method - Google Patents

Description

  The present invention relates to a paper manufacturing method. More specifically, the present invention relates to a paper manufacturing method that effectively suppresses deterioration of paper quality and the like.

  The paper manufacturing process contains a large amount of organic matter such as starch and uses warm water, so that microorganisms are easy to propagate. It is known that when microorganisms propagate in the paper manufacturing process, a biofilm called slime is formed on the walls of the pipes, tanks, and filters, resulting in failures (slime failures) such as a decrease in productivity and quality deterioration in the papermaking process. It has been.

  In order to prevent such slime damage, a method of adding an antibacterial agent called a slime control agent is known, for example, Patent Document 1 is a method of inhibiting the production of a biofilm adjacent to the surface, A method is disclosed that includes intermittently applying a biofilm inhibitor to a population of microorganisms that have the potential to produce a biofilm.

In recent years, a method of preventing slime growth and improving slime damage by water quality management by measuring oxidation-reduction potential (ORP) is known. For example, in Patent Document 2, an oxidizing disinfectant is added. A method for determining a slime control effect in an aqueous system in which slime control is performed, the step of obtaining a temporal transition of the redox potential by continuously or intermittently measuring the redox potential at at least one location of the aqueous system; and A method for determining a slime control effect, including a step of determining that the oxidation-reduction potential is in a slime forming environment due to insufficient slime control effect when the time course of the oxidation-reduction potential tends to decrease, and When it is determined by this determination method that the environment is in the formation of slime, the oxidizing disinfectant Slime control method characterized by increasing the addition amount is disclosed.
Special table 2004-537412 gazette. JP 2006-346640 A.

  It has been clarified that the growth of microorganisms in the paper manufacturing process has a great influence not only on slime damage but also on the strength of the resulting paper product. That is, when a microorganism propagates, starch is decomposed by amylase produced by the microorganism, and the strength of the obtained paper product is lowered. In particular, since waste paper has a high starch content, the strength of paper products is significantly degraded due to the propagation of microorganisms.

  On the other hand, the conventional slime control method that controls the amount of microorganisms in a papermaking process where slime damage is likely to occur cannot effectively suppress starch degradation and cannot sufficiently suppress the strength reduction of the resulting paper product. It was.

  Therefore, the main object of the present invention is to provide a paper manufacturing method that suppresses the decomposition of starch in the paper manufacturing process and does not cause deterioration in strength of paper products.

Therefore, the present invention provides a paper manufacturing method in which at least used paper is blended, and at least a paper manufacturing method for performing the following steps in the used paper pulping step.
(1) A step of measuring water quality continuously or intermittently,
(2) A step of inactivating microorganisms having starch decomposability based on the water quality measurement result obtained in the step (1).
Moreover, it is preferable that the said (2) process shall add the chemical | medical agent which can inactivate the microorganisms which have a starch resolution based on the water quality measurement result obtained at the said (1) process.
The water quality item to be measured in the step (1) is not particularly limited, but the α-amylase activity is measured, and the agent is added so that the α-amylase activity is 0.01 CU / g or less in the step (2). Is preferred. By adding the agent so that the α-amylase activity is 0.01 CU / g or less, the decomposition of starch can be suppressed more reliably.
In addition, it is preferable to measure the starch concentration in the step (1) and to inactivate microorganisms having starch resolution so that the change over time in the starch concentration becomes 0 or more in the step (2). is there.
Furthermore, the pH and redox potential are measured in the step (1), and the starch resolving power is measured so that the redox potential is 0 mV or more and the change over time of the pH and redox potential is 0 or more in the step (2). It is preferable to carry out the step of inactivating the microorganisms having
In the present invention, “the amount of change with time is 0 or more” means that the value of the object remains unchanged or increases with the passage of time.

  ADVANTAGE OF THE INVENTION According to this invention, the decomposition | disassembly of the starch in the manufacturing process of paper can be suppressed, and the manufacturing method of paper which does not produce the strength deterioration of paper products can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments for carrying out the invention will be described with reference to the drawings. In addition, embodiment described below shows an example of typical embodiment of this invention, and, thereby, the range of this invention is not interpreted narrowly.

  The paper production method according to the present invention performs water quality measurement continuously or intermittently at least in the waste paper pulping process, and at least performs a process of inactivating microorganisms having starch decomposability based on the obtained water quality measurement result.

  First, in order to determine the degree of starch decomposition, water quality is measured continuously or intermittently (hereinafter referred to as the first step). By performing water quality measurement continuously or intermittently, it is possible to observe the temporal transition of water quality in the paper manufacturing process.

  Specifically, water quality measurement points are installed at least in the waste paper pulping process. The water quality measurement point may be one point or a plurality of points. When two or more water quality measurement points are provided, it is possible to identify the location where starch tends to decompose by observing the time course of water quality at each measurement point. Optimal processing can be performed.

  Measure the water quality at the water quality measurement point and examine the time course of the water quality. It is desirable to capture the measurement results in a control unit that can accumulate data, and to automatically record and output the water quality over time.

  The water quality item measured at the water quality measurement point is not particularly limited as long as it can determine the degree of starch degradation in the paper manufacturing process. For example, α-amylase activity, organic acid concentration, starch concentration , Redox potential (ORP), pH, number of bacteria, adenosine triphosphate (ATP), glucose concentration and the like. Among these, it is preferable to measure α-amylase activity, starch concentration, pH, and oxidation-reduction potential (ORP).

  By measuring the activity of α-amylase, which is a starch degrading enzyme produced from a microorganism having starch degradability, the degree of activation of a microorganism having starch degradability can be examined. α-Amylase activity can be measured by a known method, for example, by detecting p-nitrophenol produced by reaction with α-amylase using blocked p-nitrophenyl maltoheptaoside (BPNPG7) as a substrate. The method etc. are mentioned.

  By measuring the concentration of starch and the concentration of organic acid generated by the decomposition of starch, the concentration of the actually decomposed starch can be directly examined. The organic acid concentration can be measured by a known method. For example, by using an H-type cation exchange resin as a filler in high performance liquid chromatography (HPLC), a stationary phase (H-type ion exchange group)- The organic acid can be separated and quantified by Donnan exclusion between the mobile phases. The starch concentration can also be measured by a known method. For example, the color development by the iodo starch reaction can be quantified by detecting the absorbance at 580 nm.

  In addition, it is also effective to measure ORP, pH, the number of bacteria, etc., which are indicators of the degree of microbial contamination in the system. For example, a decrease in ORP indicates that microbial contamination is progressing. In particular, when ORP is 0 mV or less, it indicates that the system is in an anaerobic state. When ORP is 0 mV or less and the amount of change with time of pH is less than 0, it is suggested that starch is decomposed to produce an organic acid.

  Next, based on the water quality measurement result obtained in the first step, the microorganisms having starch decomposing ability are inactivated (second step). Specifically, microorganisms having starch decomposing ability are inactivated so that the value of the water quality item measured in the first step falls within a range where starch decomposition does not occur.

  The value of α-amylase activity is not particularly limited, but in order to sufficiently suppress starch degradation, α-amylase activity is preferably 0.01 CU / g or less, and more preferably 0.001 CU / g or less. Is preferred.

  In the second step, it is preferable to inactivate microorganisms having starch decomposability so that the amount of change with time in the starch concentration in the liquid becomes 0 or more.

  Further, the starch concentration in the obtained paper is preferably 10 g / kg or more, and more preferably 20 g / kg or more.

  In the second step, it is preferable to inactivate the microorganism having starch degradability so that the ORP is 0 mV or more and the temporal change amount of the ORP is 0 or more. More preferably, the ORP is set to 100 mV or more. However, the present invention is not limited to the process in which a large amount of oxidizing agent and reducing agent are present in the paper manufacturing process.

  In the second step, it is preferable to inactivate microorganisms having starch degradability so that the amount of change with time of pH becomes 0 or more. In particular, the pH is preferably 6.5 or more. However, the present invention is not limited to the case where acidic papermaking is included or the step of adding a large amount of sulfuric acid band.

  The organic acid concentration in the liquid is preferably adjusted so that the total amount of formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, and valeric acid is 100 mg / L or less.

The number of bacteria is preferably 10 ⁸ CFU / mL or less, and more preferably 10 ⁷ CFU / mL or less.

ATP is preferably 10 ⁵ RLU or less, and more preferably 10 ⁴ RLU.

  The strength of the resulting paper product can be improved by inactivating microorganisms having starch-degrading ability and suppressing starch degradation. Moreover, COD can be reduced by inhibiting starch from decomposing into an organic acid. Furthermore, by suppressing the increase in organic acid and lowering the pH, it is possible to suppress the dissolution of calcium carbonate added as a filling amount in the paper manufacturing process and improve the ash yield of the resulting paper product. it can. In addition, the occurrence of pitch can be suppressed by reducing the calcium ion concentration in the water.

  A specific method for inactivating a microorganism having starch degradability is not particularly limited, and examples thereof include a method of adding a drug capable of inactivating a microorganism and a method of inhibiting intercellular communication.

  In the case of adding a drug capable of inactivating microorganisms, the drug to be added is not particularly limited, and examples thereof include an antibacterial agent. In the present invention, the bactericides to be added are not particularly limited. For example, 2,2-dibromo-3-nitropropionamide (DBNPA), 1,2-bis (bromoacetoxy) ethane, 1,4-bis (bromo Bromoacetate compounds such as acetoxy) -2-butene, 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one or metal salts thereof, 4,5- Bromonitroalcohol compounds such as isothiazolone compounds such as dichloro-2-octyl-4-isothiazolin-3-one, 2-bromo-2-nitro-1,3-propanediol and 2,2-dibromo-2-nitriloethanol; Its ester, 4,5-dichloro-1,2-dithiolane-3-one, 3,3,4,4-tetrachlorotetrahydrothio Cyclic sulfur compounds such as phen-1,1-dioxide, methylenebisthiocyanate, 5-chloro-2,4,6-trifluoroisophthalonitrile, orthophthalaldehyde, dichloroglyoxime, 5,5-dimethylhydantoin, N -Hydantoin compounds such as chloro-5,5-dimethylhydantoin and 1-bromo-3-chloro-5,5-dimethylhydantoin, reactant bactericides obtained by mixing an oxidizing agent and an ammonium salt, and the like It is done. Examples of the oxidizing agent include sodium hypochlorite, calcium hypochlorite, 1-bromo-3-chloro-5,5-dimethylhydantoin, and ammonium salts include ammonium bromide and ammonium sulfate. Is mentioned.

  The addition amount of the chemical | medical agent which can inactivate microorganisms is not specifically limited, It determines suitably based on the said water quality measurement result. For example, it is added in the range of 5 to 50 mg / L. Further, the number of additions of the drug is not particularly limited.

  In addition, as a method for inhibiting intercellular communication, for example, a method by adding a surfactant such as an anthraquinone compound, alkylbenzene sulfonic acid, a method by ultrasonic treatment or freeze-thaw treatment, by adding an antagonist, Examples include a method for inhibiting cell growth and inhibiting the growth of microorganisms and the amount of enzyme produced.

  In the paper manufacturing method according to the present invention, the type of paper to be manufactured is not particularly limited as long as at least used paper is blended, and examples thereof include paperboard, newspaper, and coated paper.

  The implementation place of the 1st process and the 2nd process in the manufacturing process of paper is not specifically limited, It shall implement at least in the used paper pulping process in which the starch of a used paper raw material tends to decompose | disassemble. Moreover, in processes other than a used paper pulping process, it is arbitrary whether the 1st process which concerns on this invention, and a 2nd process are performed, for example, you may perform only a 1st process and perform only a 2nd process. May be. Preferably, the water quality is measured continuously or intermittently in each of the waste paper pulping process, paper making process and recovery process. In the paper manufacturing process, it is preferable to perform water quality measurement in the whole process in order to confirm that the starch derived from waste paper remains sufficiently in the papermaking process.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to a following example.

<Example 1> Relationship between the amount of starch in used paper slurry and the strength of paper products Disperse 330 g of corrugated used paper in 15 L of tap water, disintegrate and beat with a beater, and test slurry having a pulp content of 2% (CSF = 315 mL) ) Was produced.
100 mg / L of Bacillus subtilis α-amylase (Kishida Kagaku) was added to 100 mL of the test slurry. After this test slurry was allowed to stand at 50 ° C. for 4 hours, the starch concentration in the slurry water was measured. The starch concentration was determined by adding 4 mL of 10-fold diluted hydrochloric acid, 0.4 mL of 0.002N iodine solution, and 0.4 mL of pure water to 3.2 mL of the filtrate obtained by filtering the test slurry with 5A filter paper. 1700 Pharma Spec: Shimadzu Corporation), the absorbance at 580 nm was measured, and the concentration was determined from a separately prepared calibration curve. The calibration curve was prepared as follows. First, 2 g of oxidized starch (MS-3800: manufactured by Nippon Shokuhin Kako) was added to 100 mL of tap water and stirred in a 90 ° C. warm bath for 30 minutes to obtain a paste solution. This paste solution was diluted with tap water so that the starch concentrations were 50, 100, 150, and 200 mg / L, and the relationship between the starch concentration and the absorbance was determined for each sample.
Next, a hand-made paper having a basis weight of about 120 g / m ² was prepared from this test slurry according to the method of JIS P 8029. The burst strength of this handsheet was measured by the method of JIS P8112. Also, 1.0 g of this handmade paper is immersed in 50 mL of pure water, and this is left to stand in a warm bath at 90 ° C. for 30 minutes to extract the starch in the paper with hot water, The starch concentration in paper was calculated | required with the same method (prototype example 1).

  The obtained results are shown in Table 1. In addition, the thing which does not add (alpha) amylase was compared as control (prototype example 2).

  It was confirmed that when the starch in the waste paper slurry was decomposed by α-amylase, the specific burst strength was greatly reduced.

<Example 2>
Corrugated used paper 330 g was dispersed in 15 L of white water collected from a paper mill producing a paperboard liner, and disaggregated and beaten with a beater to prepare a test slurry (CSF = 300 mL) having a pulp content of 2%. The water quality of the test slurry immediately after preparation was measured. A predetermined amount of antibacterial agent NH ₄ Br (manufactured by Wako Pure Chemical Industries, Ltd.) + NaOCl (manufactured by Kishida Kagaku Co., Ltd.) was added to the test slurry, and the mixture was allowed to stand at 35 ° C. for 2 days. pH and ORP were measured using pH / ORP METER (manufactured by Toko Chemical Co., Ltd .: TPX-90Si).
Further, a hand-made paper was prepared using the test slurry after storage for 2 days in the same manner as in Example 1, and the specific burst strength and the starch concentration in the paper were determined.

  Table 2 shows the results obtained when the addition amount of the antibacterial agent was 10 mg / L (Prototype Example 3) and 20 mg / L (Prototype Example 4). In addition, the antibacterial additive-free thing (prototype example 5) was compared as control.

It was shown that if a sufficient amount of an antibacterial agent is added and ORP is maintained at 0 mV or higher, starch degradation can be suppressed and the burst strength of the resulting paper can be improved (Prototype Example 4).
On the other hand, the amount of the antibacterial agent is insufficient, the ORP cannot be maintained at 0 mV or more, and when the pH is lowered, the decomposition of starch cannot be sufficiently suppressed, and the burst strength of the resulting paper can be improved. It became clear that this was not possible (Prototype Example 3).

<Example 3>
Corrugated used paper 330 g was dispersed in 15 L of tap water, 100 mL of the same white water as in Example 2 was added, and the mixture was disaggregated and beaten with a beater to prepare a test slurry (CFS = 286 mL) having a pulp content of 2%. The water quality of the test slurry immediately after preparation was measured. 20 mg / L of antibacterial agent NH ₄ Br + NaOCl was added to the test slurry, and after standing still at 35 ° C. per day, it was confirmed that the ORP was 0 mV or more and the pH did not tend to decrease, and the antibacterial agent was once a day. And stored at 35 ° C. for 3 days while adding 20 mg / L.
About this test slurry, pH, ORp, number of bacteria, starch concentration in water, starch concentration of pulp in slurry, COD (Mn), and organic acids were measured immediately after preparation (before addition of antibacterial agent) and after storage for 4 days. COD (Mn) was measured according to the method of JIS K 0102. Moreover, the measurement of organic acids was quantified using the high performance liquid chromatography (HPLC LC-6A: Shimadzu Corporation make) the filtrate which filtered 180 mL of test slurries with the wire of about 100 mesh. The column used was 7.9 mm × 30 cm Shim Pack SCR-101H 7 μm (manufactured by Shimadzu Corporation), and the eluent was a perchloric acid solution (10 mmol / L) (Prototype Example 6). In addition, the starch density | concentration of the pulp in a slurry measured the starch density | concentration in paper by the method similar to Example 1 by producing about 120 g / m < ² > hand-made paper based on JISP8029.
Furthermore, about 120 g / m ² of handmade paper was prepared from the test slurry after storage for 4 days in accordance with JIS P 8029 (Prototype Example 8). Similarly, after adding 2.5% of sulfuric acid band to the slurry for the test, cationic polymer paper strength agent: cationic polyacrylamide DS4354 (manufactured by Seiko PMC Co., Ltd.) was added to the pulp for 1.5%. % Was added to prepare hand-made paper (Prototype Example 10). The slurry having a lowered pH was adjusted to the same pH as the sample having the highest pH by adding 1% sodium hydroxide immediately before the addition of the sulfuric acid band. About the obtained hand-made paper, bursting strength was measured like Example 1, and ash content was measured based on JISP8128 in addition.

  The analysis results of the slurry are shown in Table 3. In addition, the antibacterial additive-free thing (prototype example 7) was compared as control.

  Table 4 shows the analysis results of the handsheets. In addition, the antibacterial additive-free and paper strength additive-free (prototype example 9) and the antibacterial additive-free and paper strength agent-added (prototype example 11) were compared as controls.

  By adding an antibacterial agent, OPR was maintained at 0 mV or more, and an increase in organic acids and a decrease in pH were suppressed to reduce COD (Mn). As a result, it was possible to suppress the dissolution of calcium carbonate in the waste paper slurry, and to improve the ash yield of the obtained handmade paper. Furthermore, even when a paper strength agent was added, the effect of improving the bursting strength by inhibiting the decomposition of starch was shown.

<Example 4>
550 g of used corrugated paper was dispersed in 25 L of the same white water as in Example 2, and was disaggregated and beaten in order with a beater to prepare a test slurry having a pulp content of 2% (CFS = 310 mL). The water quality of the test slurry immediately after preparation was measured. 20 mg / L of antibacterial agent NH ₄ Br + NaOCl was added to the test slurry, and allowed to stand at 35 ° C. for 3 days (Prototype Example 12). About this test slurry, the pH, ORP, the number of bacteria, the starch concentration in water, and the starch concentration of pulp in the slurry were measured in the same manner as in Examples 1 to 3 immediately after preparation (before addition of the antibacterial agent) and after storage for 3 days. Moreover, about this slurry, the measurement of ATP was measured using the ATP measuring device (Lumitester C-100: made by Kikkoman) and the ATP measuring reagent (Lucifer 250 plus: made by Kikkoman).
Furthermore, 1 L of 0.02M phosphate buffer (pH 7.4) was added to 1 L of the test slurry after storage for 3 days. Next, after adding 2.5% of the sulfuric acid band to the pulp amount, 0, 0.5, 1, 1.5% of the paper strength agent similar to that of Example 3 was added to the pulp amount, and JIS P8029. About 120 g / m ² of hand-made paper was produced by a method based on the above (Prototype Examples 14 to 17). For the obtained hand-made paper, the burst strength and the starch concentration in the paper were measured in the same manner as in Example 1, and in addition, the ash content was measured in accordance with JIS P 8128.

  The analysis results of the slurry are shown in Table 5. In addition, the antibacterial additive-free thing (prototype example 13) was compared as control.

  Table 6 shows the analysis results of the handsheets. In addition, the antibacterial additive-free thing (prototype examples 18-21) was compared as control (Table 7).

  An antibacterial agent was added to reduce the number of bacteria and ATP, while suppressing an increase in α-amylase activity and preventing a decrease in ORP, pH and starch concentration. As a result, even if no paper strength agent was added (Prototype Example 14), the burst strength was higher than that of hand-made paper (Prototype Example 21) in which 1.5% of the paper strength agent was added to the pulp amount without the addition of an antibacterial agent. Was confirmed to be large. That is, it was suggested that by deactivating microorganisms having starch decomposing ability in the paper manufacturing process for mixing waste paper, it is possible to prevent the waste paper starch from being decomposed and to reduce the paper strength agent.

<Example 5>
As antibacterial agents, 20 mg / L NH ₄ Br + NaOCl (Prototype Example 22), 20 mg / L (NH ₄ ) ₂ SO ₄ + NaOCl (Prototype Example 23), and 100 mg / L 2,2-dibromo-3-nitrilopropion A slurry was prepared in the same manner as in Example 3 except that amide (DBNPA) (Prototype Example 24) was added, and the pH, ORP, bacterial count, starch concentration in water, and starch concentration of pulp in the slurry were measured.
Further, handsheets were produced in the same manner as in Example 3 (prototype examples 26 to 28), and the burst strength and ash content were measured in the same manner as in Example 3.

  The analysis results of the slurry after 1 day and after 4 days are shown in Tables 8 and 9. In addition, the antibacterial additive-free thing (prototype example 25) was compared as control.

  Table 10 shows the analysis results of the handsheets. In addition, the antibacterial agent-free thing (prototype 29) was compared as control.

It was confirmed that even when an antibacterial agent other than NH ₄ Br + NaOCl is added, an agent capable of inactivating microorganisms having starch degradability can be maintained to maintain ORP at 0 mV or more and prevent a decrease in pH. . As a result, it was confirmed that the increase in α-amylase activity could be suppressed, starch degradation could be suppressed, and the paper strength of the resulting paper product could be improved.

Claims (4)

A method for producing paper in which at least used paper is blended,
In at least waste paper pulping process,
(1) a step of continuously or intermittently measuring water quality , and (2) performing a step of inactivating microorganisms having starch resolution based on the water quality measurement result obtained in step (1) ,
The pH and redox potential are measured in the step (1), and the starch has a resolution so that the redox potential is 0 mV or higher and the change over time of the pH and redox potential is 0 or higher in the step (2). A method for producing paper, comprising performing a step of inactivating microorganisms .   2. The paper according to claim 1, wherein the step (2) is a step of adding an agent capable of inactivating microorganisms having starch decomposability based on the water quality measurement result obtained in the step (1). Manufacturing method.   The step of measuring α-amylase activity in the step (1) and the step of inactivating microorganisms having starch degradability so that the α-amylase activity is 0.01 CU / g or less in the step (2). The method for producing paper according to claim 1 or 2.   The step (1) measures the starch concentration, and the step (2) performs the step of inactivating microorganisms having starch decomposability so that the amount of change with time in the starch concentration becomes 0 or more. Item 4. The method for producing paper according to any one of Items 1 to 3.