JP4775268B2 - Paper manufacturing method using starch - Google Patents

Description

  The present invention relates to a paper manufacturing technique. More specifically, the present invention relates to a technique for preventing deterioration of paper quality and productivity reduction in a paper manufacturing method using starch.

  In the raw material preparation process and papermaking process in the papermaking process, bacteria and fungi are propagated using cellulose and various additives as nutrients, and so-called “slime” is generated. This “slime” is a biofilm composed of microorganisms and mucilage produced by the microorganisms. If this slime is peeled off the wall of the process equipment and mixed into the paper, the quality of the paper product will be reduced, or the continuous operation will be hindered by causing paper breakage in the paper making process, and the production efficiency will be greatly reduced. Invite problems.

  For this reason, in the papermaking white water circulation system, slime suppression has been performed by adding chemicals. This type of drug is generally referred to as a “slime control agent”, and has been proposed in, for example, Patent Documents 1 to 4.

  In recent years, starches such as cationic starch and amphoteric starch have been added to raw materials for the purpose of improving the productivity and quality of paper. In this case, slime control is becoming an increasingly important technology because starch, which is a nutrient source for microorganisms, enters the white paper circulation system, which is an aqueous environment suitable for the growth of microorganisms even at water temperature and pH. .

Microorganisms in the slime are occupied by bacteria with high amylase-producing ability, which is an amylolytic enzyme. This bacterial amylase activity results in degradation of starch added to the raw material, resulting in reduced water resistance and strength of the paper, reduced paper sizing, squeeze yield, reduced aqueous solution, and insufficient anion trash fixation. This leads to a decrease in productivity.
JP-A-6-009307. Japanese Patent Application Laid-Open No. 10-120509. JP2003-012413A. Special table 2004-537412 gazette.

  In recent years, due to the expansion of neutral papermaking, the number of paper manufacturing processes that use starch has increased rapidly. This has led to degradation of paper quality and productivity reduction caused by starch degradation due to amylase activity of microorganisms that form slime. The problem is becoming apparent.

  Therefore, the main object of the present invention is to provide a technique for effectively preventing the deterioration of the quality of the paper using starch by implementing slime control by a novel method.

  The present invention is directed to a paper manufacturing method in which starch is added to a paper raw material. Specifically, in the paper manufacturing method in which starch is added to the paper raw material, the amylase activity is measured at a predetermined location in the manufacturing process, and the production of paper in which the slime control agent is added based on the measured value. Provide a method. “Adding a slime control agent based on the measured value” means selecting or determining the type, added amount (concentration), addition timing, etc. of the slime control agent in consideration of the degree of the amylase activity measurement value. Means that. In the present invention, the “starch” is not limited to a narrow one, and includes, for example, processed starch such as cationized starch, amphoteric starch, pregelatinized starch, and esterified starch.

  In this method, a threshold value for the amylase activity may be determined in advance, and the amount of the slime control agent added may be increased when the threshold value is exceeded. For example, amylase activity is monitored continuously or periodically over time, and when the measured value exceeds a predetermined threshold, the amount of the slime control agent added is increased to increase the amylase activity in the system. In order to prevent the progress of starch degradation. The threshold value is not particularly limited, but can be generally set to 0.002 CU / g.

  That is, in the present invention, slime control agent is added to appropriately suppress slime formation, and as a result, the degradation of the starch is suppressed by reducing the amylase activity caused by the microorganisms constituting the slime, As a result, the paper quality is prevented from being deteriorated, and at the same time, the paper productivity is prevented from being lowered.

  According to the present invention, for the purpose of improving the productivity and quality of paper, starch added to the paper raw material (also referred to as internally added starch) is a microorganism that constitutes slime generated in the system. It can prevent effectively that it decomposes | disassembles by amylase activity. As a result, the desired function of the starch can be exhibited, the quality and quality of the paper used can be stabilized and improved, and the productivity can also be stabilized or improved.

<Example 1>
Experimental purpose. It is verified that the addition of the slime control agent brings about the suppression of slime formation and the reduction of amylase activity in the starch-containing artificial white water system, and also has a positive effect on the quality of the paper formed using the artificial white water.

Experimental method.
A torque type with a configuration in which a stationary outer cylinder (inner diameter: 180 mm, inner volume: 3000 mL) made of vinyl chloride resin is prepared, and a rotary inner cylinder (made of SUS304, inner diameter: 80 mm) is installed coaxially in this outer cylinder. A slime adhesion test apparatus was used. In this test apparatus, artificial white water continuously supplied to a predetermined storage tank is introduced into the cylinder by a circulation pump, and the overflow water from the cylinder returns to the storage tank and is introduced into the cylinder again. It has become.

  The internal cylinder was rotated at 100 rpm, and the rotational torque of the internal cylinder was measured with a Brookfield torque meter (Toki Sangyo: RE500H). That is, if slime adheres to the inner cylinder, the friction resistance on the surface of the inner cylinder increases and the rotational torque of the inner cylinder increases, and the measured rotational torque value is automatically recorded, and the rotational torque value increases. The time for starting to become the slime deposition start time was taken as the time.

  The artificial white water used in the experiment is an aqueous solution of pH 7 in which water-soluble starch and ammonium sulfate are dissolved in city water from which residual chlorine has been removed. And the microbe isolate | separated from the coating raw paper papermaking white water was isolate | separated, and the culture solution was supplied so that it might become a 7th power order in the said artificial white water. The artificial white water supply line was controlled so that the temperature of the artificial white water in the cylinder was about 30 ° C. A predetermined concentration of a slime control agent was added to this artificial white water, and the number of days of slime adhesion (with respect to the internal cylinder) and amylase activity (CU / g) after 7 days were measured (see Table 1 below for the measurement results). . The amylase activity was performed using a commercially available amylase measurement kit (manufactured by Megazyme International Ireland) according to the manual of the kit.

  Next, after completion of the test, pulp and calcium carbonate are added to the above artificial white water for test containing amylase so that the pulp content is 0.9% and the calcium carbonate content is 0.1%. A slurry (CSF 380 mL) was prepared. To this slurry, add 0.5% solid content of sulfuric acid band, 0.7% solid content of amphoteric starch (Nippon NSC, CATO3212), and neutral rosin sizing agent (CC1401, made by Seiko PMC). This was “test slurry”.

  Using this “slurry for test”, hand-made paper weighing about 90 g was prepared according to the method of JIS P8029. For this handmade paper, according to the method of JIS P8113, the tensile strength (indicated by the tear length) is measured by the method of JIS P8112, the degree of sizing of the paper is evaluated, and the liquid absorptivity of the paper is evaluated. 180 mL was filtered through a wire of about 100 mesh, and the amount of filtered water for 10 seconds was determined. Moreover, 40 mL was similarly filtered and the turbidity of the filtrate was also measured.

  Experimental result. The experimental results of Example 1 are summarized in the following “Table 1”.

  As can be seen from the experimental results shown in the above-mentioned “Table 1”, a slime control agent is added to starch-containing artificial white water under conditions where starch-degrading enzyme-producing bacteria, that is, bacteria having amylase activity are present, or By increasing the concentration of the slime control agent, the number of days of slime adhesion could be extended.

  In addition, as can be seen from the above experimental results, by adding a slime control agent to starch-containing artificial white water in the presence of starch-degrading enzyme-producing bacteria, or by increasing the addition concentration of the slime control agent, It was verified that amylase activity was reduced.

  That is, according to these results, in the papermaking white water system similar to the artificial white water used in this experiment, the slime control agent can suppress the formation of slime on the inner wall surface of the production apparatus and reduce the amylase activity. Was confirmed.

  Next, as can be seen from the experimental results on the handmade paper formed from the test slurry, the handmade paper formed from the slurry using artificial white water in which slime formation is suppressed and the amylase activity is reduced by the addition of the slime control agent. Then, the tearing length was increased, the steecht size was increased, the freeness was improved, and the turbidity was suppressed.

  This result indicates that by using slime-controlled white water and raw materials, it is possible to effectively prevent the water resistance and tensile strength of the paper from being lowered, the paper's squeecht sizing degree and the yield from being reduced.

  Here, examples of slime control agents that can be used in the present invention include bromoamide compounds such as 2,2-dibromo-3-nitrilopropionamide (DBNPA in Table 1) and N-bromoacetamide, 1,2- Bromoacetate compounds such as bis (bromoacetoxy) ethane and 1,4-bis (bromoacetoxy) -2-butene (BBAB in Table 1), 2-methyl-4-isothiazolin-3-one, 5-chloro- Isothiazolone compounds such as 2-methyl-4-isothiazolin-3-one or its metal salt, 4,5-dichloro-2-octyl-4-isothiazolin-3-one, 2-bromo-2-nitro-1,3- Bromonitroalcohol compounds such as propanediol, 2,2-dibromo-2-nitroethanol and their esters, 4,5-dichloro-1,2-dithiolan-3-one (dithio in Table 1) ), Cyclic sulfur compounds such as 3,3,4,4-tetrachlorotetrahydrothiophene-1,1-dioxide, methylene bis-thiocyanate (MBT in Table 1), 5-chloro-2,4,6-trifluoroisophthalate Taronitrile, orthophthalaldehyde, dichloroglyoxime, 5,5-dimethylhydantoin, N-chloro-5,5-dimethylhydantoin, 1-bromo-3-chloro-5,5-dimethylhydantoin (BCDMH in Table 1), etc. Hydantoin compounds, reactant bactericides obtained by mixing an oxidizing agent and an ammonium salt, and the like can be employed. Examples of the oxide include sodium hypochlorite, calcium hypochlorite, and 1-bromo-3-chloro-5,5-dimethylhydantoin. Examples of ammonium salts include ammonium bromide and ammonium sulfate. Can be illustrated.

<Example 2>
Experimental purpose. Using an actual papermaking machine that uses starch-containing raw materials, the effects of slime control on amylase activity, white water turbidity, and yield rate will be verified.

  Experimental method. Amylase activity was measured at each step using a machine in which amphoteric starch (NTO Japan, CATO3212) was added to a machine chest and 5 kg / t (raw material) was added to make a coated base paper. The measurement results are shown in the following “Table 2”. FIG. 1 is a reference diagram showing a basic configuration of the papermaking machine.

  From the measurement results shown in “Table 2”, it was found that the amylase activity of coat broke and drive rooke was high. Therefore, the paper product is added three times a day so that the reaction product (slime control agent) of ammonium bromide and sodium hypochlorite can be retained in the headbox slurry for 2 minutes at an effective chlorine concentration of 2 mg / L. In addition to the system, the reaction product was added to the coat broke and the drive stroke so that the effective chlorine concentration would always remain 0.5 mg / L or more.

  Experimental result. The amylase activity of the machine chest to which amphoteric starch was added decreased from 0.034 CU / g to 0.0015 CU / g, and the white water turbidity also decreased from 910 NTU to 390 NTU. The yield rate also increased from 61% to 64%. From these results, it was suggested that slime control, white water turbidity, yield rate and the like can be controlled using amylase activity as an index.

<Example 3>
Experimental purpose. It is verified that by using slime control using amylase activity as an index, it is possible to prevent turbidity increase and thus improve paper quality.

  Experimental method. In the machine chest of the paper making machine, the same amphoteric starch as above is 5 kg / t (for raw material), and the reaction product (slime control agent) of ammonium bromide and sodium hypochlorite is 2 mg / L for 15 minutes. The amylase activity in the machine chest and the turbidity (anion trash) in the head box were measured on a machine where the coated base paper was continuously operated for 30 days.

  The results are shown in “Table 3” below. In the examples in the following Table 3, when the amylase activity exceeded 0.002 CU / g (15th day), the addition amount of the reactant (slime control agent) was increased, and the effective chlorine concentration was 4 mg. / L is an experimental system that employs a method adjusted so that it can be held for 15 minutes, while the comparative example is an experimental system that did not increase the amount of the reactant added.

  Experimental result. When the amylase activity exceeded 0.002 CU / g (15th day), the amount of the slime control agent added was increased, and in the example adjusted so that it could be maintained at 4 mg / L for 15 minutes, the amylase activity turned to decrease. It was found that the turbidity component fixing ability of amphoteric starch was recovered and the turbidity was also significantly reduced (see Table 3). As a result, anion trash decreased, no increase in spots was observed, and continuous operation for 30 days became possible without a decrease in productivity.

  On the other hand, in the comparative example, the amylase activity reached 0.002 CU / g on the 15th day from the start of production, the turbidity also reached 743 NTU, and thereafter the addition amount of the slime control agent was not increased. Turbidity further increased (see Table 3). As a result, the anion trash in the system increased, the spots derived from the anion trash increased, and the paper productivity deteriorated.

  Based on the above results, in the paper making process, the amylase activity is measured at a predetermined location (for example, a machine chest), and by using this measured value as an index, the addition timing and the addition amount of the slime control agent are determined. It was found that it can be used to improve the quality stability and productivity.

  The present invention can be used as a paper manufacturing technique in which starch is added to a raw material. More specifically, it can be used as a technique for stabilizing or improving paper quality and a technique for stabilizing or improving productivity in the manufacturing technique.

It is a reference figure which shows the basic composition of the papermaking machine used in Example 2. FIG.

Claims (3)

In a method for producing paper in which starch is added to the paper raw material,
A method for producing paper, wherein amylase activity is measured at a predetermined location in the production process, and a slime control agent is added based on the measured value.   The paper manufacturing method according to claim 1, wherein a threshold value of the amylase activity is determined in advance, and when the threshold value is exceeded, the amount of the slime control agent added is increased.   The method for producing paper according to claim 1, wherein the slime control agent suppresses slime formation to reduce amylase activity, thereby suppressing degradation of the starch and preventing deterioration of paper quality.

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