JP2020133097A - Pitch trouble suppression method - Google Patents

Abstract

To provide a pitch trouble suppression method, that is useful for suppressing/preventing pitch stains in the papermaking process.SOLUTION: The pitch trouble suppression method is a pitch trouble suppression method for controlling the size of a pitch contained in the pulp slurry in the pulping step and/or the preparation step to suppress the occurrence of pitch trouble in the papermaking process, including an oxidizing agent addition step in which an oxidizing agent is added to at least one location pulp slurry in the pulping step and the preparation step so that the average particle size of the pitch contained in the pulp slurry is less than 150 μm, and/or a pitch dispersing agent addition step in which a pitch dispersing agent is added to at least one location pulp slurry in the pulping step and the preparation step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for suppressing pitch obstacles in a papermaking process.

Conventionally, various chemicals have been developed in order to suppress or prevent obstacles due to pitch in the papermaking process (particularly the papermaking process).
Pitch is a water-insoluble adhesive substance mainly composed of organic substances derived from wood, pulp, natural resins liberated from paper, gum substances, and additives used in the manufacturing process of paper and pulp. Say.

Generally, the pitch is dispersed in a colloidal state in the process water (pulp slurry or white water) of the paper and pulp manufacturing process, but some external action such as large shearing force, rapid change in pH, sulfuric acid It is thought that the colloidal state is destroyed by excessive addition of the band (aluminum sulfate), and the colloidal state is aggregated and enlarged.
Due to its adhesiveness, this agglomeration and enormous pitch not only adheres to paper and pulp, as well as manufacturing equipment such as fan pumps, pipes, chests, wires, felts, and rolls, but also the deposits peel off. And reattaches to paper and pulp. Then, the stains and defects of the formed paper deteriorate the quality of the paper product, and the generated paper breakage causes obstacles such as a decrease in productivity and workability.

In recent years, due to the diversification of paper, the types of additives and the amount used thereof have increased, the ratio of used paper used has increased, and as the water used in the papermaking process has become more closed, pitch obstacles have increased more than before. As the occurrence of is increasing, the form of occurrence is becoming more complicated.
For example, not only the pitch derived from mechanical pulp such as conventional ground pulp (GP) and thermomechanical pulp (TMP) and the pitch derived from chemical pulp such as kraft pulp (KP), but also the pitch trouble derived from used paper raw materials has increased. ing. Examples of the pitch derived from the used paper raw material include synthetic resins such as magazine back glue (polyvinyl acetate) and labels (acrylic adhesive glue).
In addition, in order to improve productivity, the problem of pitch stains on wire parts, rolls of press parts, blankets, and blanket suction boxes has become apparent due to the increase in size of equipment and the speed of papermaking, in combination with other factors. There is.

As a method of suppressing such a pitch disorder, a method of adsorbing a pitch component on an inorganic compound such as fine talc, a method of fixing pitch particles before aggregation to pulp fibers, a method of dispersing pitch particles, and a combination thereof. Methods have been proposed and put into practical use.

For example, Patent Document 1 describes cationic polymers and higher aliphatic amines selected from polydiallyl dimethylammonium salts having a molecular weight of 20,000 to 100,000 and epichlorohydrin-dialkylamine condensates having a molecular weight of 20,000 to 100,000. A pitch disorder inhibitor for a paper / pulp manufacturing process containing ethylene oxide or a nonionic surfactant to which ethylene oxide and propylene oxide are added as an active ingredient is disclosed.
However, it cannot be said that the conventional additives and methods have a sufficient effect of preventing pitch disorders, and more effective agents and methods are desired.

Further, Patent Document 2 describes a method for suppressing pitch obstacles in a paper manufacturing system that makes paper from a paper raw material, and by performing a treatment that suppresses an increase in calcium ion concentration in an aqueous system of the paper manufacturing system, pitch adhesion is performed. Is disclosed to be suppressed.

In addition, Patent Document 3 describes a method of using a combination of lipase and an oxidizing agent for pitch control in a papermaking process, thereby controlling sediment-forming pollutants containing pitch or other fiber components. Is described. Furthermore, it is described that contacting the fiber with a combination of lipase and at least one peroxide source-free oxidant frees organic pollutants from the fiber and controls deposit-forming pollutants.

As described above, a method for suppressing pitch obstacles in the papermaking process for producing paper has been conventionally studied, but a pulp slurry in which pitch obstacles are suppressed in the papermaking process, that is, to the extent that pitch obstacles do not occur in the papermaking process. Pulp slurries containing controlled pitches have not been studied much.

Japanese Unexamined Patent Publication No. 2004-044067 Japanese Unexamined Patent Publication No. 2011-226032 Patent No. 6084689

"Pitch reduction method in paperboard system" Paper Paper Gikyo Magazine Vol. 58, No. 4_P. 468-477_April 2004

Therefore, an object of the present invention is to provide a pitch obstacle suppressing method useful for suppressing / preventing pitch stains in a papermaking process.

Generally, the papermaking process is divided into 1) pulping process, 2) preparation process for compounding chemicals, 3) papermaking process, and 4) finishing process. In the conventional pitch obstacle suppressing method, the preparation process is performed. And a method of adding a pitch control agent to the pulp slurry in the papermaking process to suppress pitch obstacles mainly caused in the papermaking process has been proposed. However, such a method cannot be said to have a sufficient effect of preventing pitch obstacles in the papermaking process, and a more effective method for suppressing pitch obstacles is desired.

As a result of intensive research to solve the above problems, the present inventors have controlled the pitch particle size in the pulp slurry before being introduced into the papermaking process so as not to be larger than a specific size. , It was found that the occurrence of pitch failure in the papermaking process can be suppressed. Then, a specific oxidizing agent is added to the pulp slurry in at least one place of the pulping step and the preparation step, and / or a pitch dispersant is added to the pulp slurry in at least one place in the pulping step and the preparation step. We have found the fact that the addition suppresses the pitch from becoming larger than a specific size and exerts an excellent effect of suppressing / preventing pitch stains in the papermaking process, and has completed the present invention.
Further, the present inventors have found that the occurrence of pitch obstacles in the papermaking process can be suppressed by controlling the particle size of the pitch in the pulp slurry after being introduced into the papermaking process so as to be a specific size or less. It was. Then, by adding a specific oxidizing agent and a pitch dispersant to the pulp slurry in at least one place in the papermaking process, the pitch is reduced to a specific size or less, and the excellent suppression / prevention effect of pitch stains in the papermaking process is achieved. We have found the facts to be exhibited and have completed the present invention.
Further, the present inventors control the particle size of the pitch in the pulp slurry before and / or after the introduction into the papermaking process so as to be a specific size or less, thereby preventing the occurrence of pitch failure in the papermaking process. We found that it could be suppressed. Then, a specific oxidizing agent and / or pitch dispersant is added to the pulp slurry at least in the pulping step and / or the preparation step, and further, a specific oxidizing agent and / or a specific oxidizing agent and / or a pitch dispersant are added to the pulp slurry at least in the papermaking step. / Or by adding a pitch dispersant, the pitch in the pulp slurry in the papermaking process is reduced to a specific size or less, and the fact that the pitch stain in the papermaking process is excellently suppressed / prevented is exhibited, and the present invention is completed. I came to do it.

The present invention is a pitch failure suppressing method for controlling the size of pitch contained in a pulp slurry in a pulping step and / or a preparation step to suppress the occurrence of pitch failure in a papermaking step, and is included in the pulp slurry. An oxidant addition step of adding an oxidant to at least one pulp slurry in the pulping step and the preparation step so that the average particle size of the pitch is less than 150 μm, and / or the pulping step and the above. The pitch obstacle suppressing method is characterized by comprising a pitch dispersant addition step of adding a pitch dispersant to at least one pulp slurry in the preparation step.
Further, the present invention is a pitch failure suppressing method for controlling the size of pitch contained in the pulp slurry in the papermaking process and suppressing the occurrence of pitch failure in the papermaking process, and the average of the pitches contained in the pulp slurry. An oxidant addition step of adding an oxidant to at least one pulp slurry in the papermaking process and a pitch dispersant are added to at least one pulp slurry in the papermaking process so that the particle size is less than 150 μm. It is also a pitch obstacle suppressing method characterized by including a pitch dispersant addition step.
Further, the present invention is a pitch failure suppressing method for controlling the size of the pitch contained in the pulp slurry in the pulping step and / or the preparation step and the paper making step, and suppressing the occurrence of the pitch failure in the paper making step. Then, the first oxidizing agent is added to at least one pulp slurry in the pulping step and the preparing step so that the average particle size of the pitch contained in the pulp slurry in the papermaking step is less than 150 μm. It comprises a first oxidant addition step and / or a first pitch dispersant addition step of adding a first pitch dispersant to at least one pulp slurry in the pulping step and the preparation step. , A second oxidant addition step of adding a second oxidant to at least one pulp slurry in the papermaking process, and / or a second pitch dispersant in at least one pulp slurry in the papermaking process. It is also a pitch obstacle suppressing method characterized by including a step of adding a second pitch dispersant to be added.
The oxidizing agent is preferably at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide, hydrogen peroxide, and bound halogen.
The first oxidizing agent and the second oxidizing agent are at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide, hydrogen peroxide, and bound halogen. It is preferable to have.
Further, in the pitch dispersant addition step, it is preferable to add the pitch dispersant to the pulp slurry having a residual chlorine concentration of 0.5 mg / L or more and 30 mg / L or less.
Further, in the first pitch dispersant addition step and the second pitch dispersant addition step, the pitch dispersant can be added to the pulp slurry having a residual chlorine concentration of 0.5 mg / L or more and 30 mg / L or less. preferable.
Further, the method for suppressing pitch obstacles of the present invention includes the above-mentioned oxidant addition step and the above-mentioned pitch dispersant addition step, and the oxidant is a group consisting of hypochlorite, chlorite, chlorine dioxide and bound halogen. It is preferably at least one selected from the above.
Further, the pitch dispersant is preferably at least one selected from the group consisting of a surfactant, a cationic polymer and an organic solvent.
Further, the first and second pitch dispersants are preferably at least one selected from the group consisting of surfactants, cationic polymers and organic solvents.
Hereinafter, the present invention will be described in detail.

The present invention is a pitch failure suppressing method for controlling the size of pitch contained in a pulp slurry in a pulping step and / or adjusting step to suppress the occurrence of pitch failure in a papermaking step, wherein the pitch contained in the pulp slurry is suppressed. An oxidant addition step of adding an oxidant to at least one pulp slurry in the pulping step and the preparation step and / or at least one place in the pulping step and the preparation step so that the average particle size is less than 150 μm. This is a pitch obstacle suppressing method including a step of adding a pitch dispersant to the pulp slurry of the above.
By providing an oxidant addition step of adding an oxidant to at least one pulp slurry in the pulping step and the preparation step, the pitch size in the pulp slurry can be miniaturized. Therefore, the bloated pitch can be suppressed, and the occurrence of pitch failure in the papermaking process can be suppressed.
Further, by providing a pitch dispersant addition step of adding a pitch dispersant to at least one pulp slurry in the pulping step and the preparation step, the pitch dispersibility can be improved before the pitch size in the pulp slurry is enlarged. Since it can be improved and the agglomeration of the pitch is suppressed, the pitch can be maintained at a small size without causing an enlargement of the pitch. Therefore, it is possible to suppress the occurrence of pitch failure in the papermaking process.

Further, the present invention is a pitch failure suppressing method for controlling the size of pitch contained in the pulp slurry in the papermaking process and suppressing the occurrence of pitch failure in the papermaking process, and the average of the pitches contained in the pulp slurry. An oxidant addition step of adding an oxidant to at least one pulp slurry in the papermaking process and a pitch dispersant are added to at least one pulp slurry in the papermaking process so that the particle size is less than 150 μm. It is also a pitch obstacle suppressing method characterized by including a pitch dispersant addition step.
By providing an oxidant addition step for adding an oxidant to at least one pulp slurry in the papermaking process, the pitch size in the pulp slurry in the papermaking process can be miniaturized. Therefore, the enlargement of the pitch is suppressed and the miniaturization is promoted, so that the occurrence of pitch failure in the papermaking process can be suppressed.
Further, by providing a pitch dispersant addition step of adding a pitch dispersant to at least one pulp slurry in the papermaking process, the pitch dispersibility is improved before the pitch size in the pulp slurry in the papermaking process is enlarged. Since the agglomeration of the pitch is suppressed, the pitch can be maintained at a small size without causing an enlargement of the pitch. Therefore, it is possible to suppress the occurrence of pitch failure in the papermaking process.

Further, the present invention is a pitch failure suppressing method for controlling the size of the pitch contained in the pulp slurry in the pulping step and / or the preparation step and the paper making step, and suppressing the occurrence of the pitch failure in the paper making step. Then, the first oxidizing agent is added to at least one pulp slurry in the pulping step and the preparing step so that the average particle size of the pitch contained in the pulp slurry in the papermaking step is less than 150 μm. It comprises a first oxidant addition step and / or a first pitch dispersant addition step of adding a first pitch dispersant to at least one pulp slurry in the pulping step and the preparation step. , A second oxidant addition step of adding a second oxidant to at least one pulp slurry in the papermaking process, and / or a second pitch dispersant in at least one pulp slurry in the papermaking process. It is also a pitch obstacle suppressing method characterized by including a step of adding a second pitch dispersant to be added.
By providing the first oxidant addition step of adding the oxidant to the pulp slurry at at least one place in the pulping step and / or the preparation step, the pitch size in the pulp slurry can be miniaturized, and the pitch can be reduced. Enlargement is suppressed. Further, by providing the first pitch dispersant addition step of adding the pitch dispersant to the pulp slurry at at least one place in the pulping step and / or the preparation step, the pitch size in the pulp slurry is not enlarged. The dispersibility of the pitch can be improved, the aggregation of the pitch is suppressed, and the size can be maintained at a small size without causing the pitch to be enlarged. Further, a second oxidant step of adding an oxidant to the pulp slurry at least one place in the papermaking process and / or a second pitch dispersant adding a pitch dispersant to the pulp slurry at at least one place in the papermaking process. By providing the addition step, the pitch size in the pulp slurry in the papermaking process can be miniaturized and / or the pitch dispersibility can be improved before the pitch size is enlarged. As a result, pitch agglomeration in the pulp slurry in the papermaking process is suppressed, and the size can be maintained at a small size without causing bloat.

The pitch obstacle suppressing method of the present invention is either a method of controlling the pitch size contained in the pulp slurry in the pulping step and / or the preparation step, or a method of controlling the pitch size contained in the pulp slurry in the papermaking step. It may be present, or it may be a combination thereof. The description of the terms used in the pitch obstacle suppressing method of the present invention is a method of controlling the pitch size contained in the pulp slurry in the pulping step and / or the preparation step, and / or the pitch contained in the pulp slurry in the papermaking step. It is common in the method of controlling the size. In the present specification, the compounds used in the oxidant addition step, the first oxidant addition step, and the second oxidant addition step, the addition method, and the preferred embodiment are common. Therefore, in the following description, all of them are referred to as an oxidizing agent addition step, and the oxidizing agent, the first oxidizing agent and the second oxidizing agent used here are referred to as an oxidizing agent. Further, the compounds used in the pitch dispersant addition step, the first pitch dispersant addition step, and the second pitch dispersant addition step, the addition method, and the preferred embodiment are common. Therefore, in the following description, all of them are referred to as pitch dispersant addition steps, and the pitch dispersant, the first pitch dispersant and the second pitch dispersant used here are referred to as pitch dispersants.
Further, in the present specification, the papermaking process includes a pulping process, a preparation process, and a papermaking process.

In the pitch obstacle suppressing method of the present invention, the pulping raw material may be either wood or used paper.

For example, when used paper is used as a raw material, the pulping step of the used paper mainly includes a disintegration step, a rough selection / selection step, and a dehydration / washing step. Further, it may include a deinking step of removing the ink contained in the used paper and a bleaching step of chemically bleaching the pulp. To explain each process in detail, a pulper step of mixing waste paper as a raw material with water to make a pulp slurry by mechanical force, a rough selection (dust removal) step of removing foreign substances contained in the waste paper, and a deinking agent. Deinking process to remove ink components by adding, selection process to separate foreign matter and pulp contained in waste paper with a screen, washing process to wash pulp slurry with water, dehydration process to dehydrate pulp, add bleaching agent This is a bleaching process for bleaching pulp. The water used in each of the above steps and the drained water are called white water. Further, a mixture of used paper and white water, which are raw materials in the pulper process, is called a pulp slurry.

When wood is used as a raw material, for example, the pulping step of chemical pulp mainly includes a wood preparation step, a cooking step, a selection / washing step, and a dehydration step. In addition, it may include a bleaching step that chemically bleaches the pulp. In the above-mentioned cooking step, chemicals are added to the chips, and the chips are boiled at high temperature and high pressure to melt the resin (lignin), take out the fiber content, and pulp the chips. That is, the pulp raw material becomes a pulp slurry through a cooking step. In addition, the pulping step of mechanical pulp includes a crushing step, a dust removing step and a concentration step. In addition, it may include a bleaching step that chemically bleaches the pulp. In the above process, it is mechanically fiberized to form a pulp slurry.

In the pitch obstacle suppressing method of the present invention, the oxidant addition step and / or the pitch dispersant addition step is performed on the pulp slurry in at least one of the devices for mechanically sharing the pulp slurry, and / or the above. It is preferable to add it to the pulp slurry on the upstream side of the equipment. By adding the oxidant and / or the pitch dispersant to at least one of the devices for mechanically sharing and / or on the upstream side thereof, the oxidant and / or the pitch dispersant and the pulp slurry can be obtained. After being sufficiently stirred and mixed, the pitch component contained in the pulp slurry and the above-mentioned oxidizing agent and / or pitch dispersant are sufficiently contacted to promote miniaturization and / or dispersibility of the pitch component, and the pitch component has a minute size. It can be kept in a stable and dispersed state. Therefore, the occurrence of pitch failure in the papermaking process can be further suppressed.
In the present invention, the expressions "upstream and downstream" are determined by the flow direction of the pulp slurry and white water in the piping and equipment, and the direction in which the pulp slurry and white water flow is downstream, and the opposite direction. Is upstream. For example, in the raw material line where the pulped raw material is, the one closer to the pulped raw material is upstream. Further, for example, in the white water supply line for supplying white water, the one closer to the white water pit is upstream.

In the present invention, the device for applying mechanical share means, for example, a device that agitates the pulp slurry at a rotation speed of 50 rpm or more and 3000 rpm or less in the device, and the stress acting on the pulp slurry in the device flows through the pipe. A location that is greater than the stress acting on the pulp slurry. Specific examples include a pulper, a refiner, a screw press, a double separator, a selection screen, a rotary screen, a washer, a thickener and a fan pump. Preferred specific equipment includes pulpers, refiners and fan pumps.

Further, in the present invention, it is more preferable that the oxidant addition step and / or the pitch dispersant addition step is on the upstream side of the drainage line. As described above, by adding an oxidizing agent and / or a pitch dispersant to the pulp slurry on the upstream side of at least one of the devices for mechanically sharing, the pitch component in the pulp slurry is miniaturized and / or dispersed. The properties are promoted, and then the pitch components dispersed through the drainage line are discharged together with the white water from the raw material lines in the pulping step and the preparation step, so that the amount of pitch components in the pulp slurry can be reduced. Therefore, pitch obstacles in the papermaking process can be prevented more effectively.

The drainage line means a line for discharging white water from the raw material line through which the pulp slurry flows to the outside of the system of the pulping process, the preparation process and the papermaking process, and includes a line for collecting the white water for reuse. Absent.
In addition to the method of discharging the pitch component from the raw material line together with white water via the drainage line as described above, the method of discharging the pitch component from the pulping step and the preparation step to the outside of the system is a pulp slurry. There is also a method of transferring from the pulping process and the preparation process to the subsequent papermaking process, but the above-mentioned "drainage line" corresponds to a line in which the pitch component is discharged from the raw material line together with white water.

The specific oxidizing agent used in the present invention is preferably at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide, hydrogen peroxide, and bound halogen.

Specific examples of the hypochlorite include sodium hypochlorite, potassium hypochlorite, calcium hypochlorite and the like, and in the present invention, one of these may be used alone or in combination of two or more. Can be used in combination.

Specific examples of the chlorite include sodium chlorite, potassium chlorite, calcium chlorite and the like, and in the present invention, one of these chlorites may be used alone or in combination of two or more. be able to.

Since chlorine dioxide is an extremely unstable chemical substance, it is extremely difficult to store and transport it. Therefore, it is preferable to produce (produce) chlorine dioxide on the spot by a known method and adjust the addition concentration before use.
For example, chlorine dioxide can be produced by the following reaction, and a commercially available chlorine dioxide generator (device) can also be used.
(1) Reaction of sodium hypochlorite with hydrochloric acid and sodium chlorite NaOCl + 2HCl + 2NaClO ₂ → 2ClO ₂ + 3NCl + H ₂ O
(2) Reaction of sodium chlorite with hydrochloric acid 5NaClO ₂ + 4HCl → 4ClO ₂ + 5 NaCl + 2H ₂ O
(3) Reaction with sodium chlorate, hydrogen peroxide and sulfuric acid 2NaClO ₃ + H ₂ O ₂ + H ₂ SO ₄ → 2ClO ₂ + Na ₂ SO ₄ + O ₂ + 2H ₂ O

Examples of the bound halogen include bound chlorine and bound bromine, and specifically, monochrome lamin and / or monobrolamin are preferable.
The monochloramine and monochloramine are mild oxidizing agents produced by a reaction such as OCl- (Br-) + NH ₄ + → NH ₂ Cl (Br) + H ₂ O. For example, monochloroamine can be produced by mixing sodium hypochlorite and an ammonium compound, and specific examples of the ammonium compound include ammonium sulfate, ammonium bromide, ammonium chloride, and ammonium sulfamate, which are used alone. Or two or more types can be used in combination.
The molar ratio of sodium hypochlorite to the ammonium compound is preferably 1: 1 to 1: 2 as the molar ratio of residual chlorine to nitrogen in one or more embodiments.

In the present invention, the amount of the oxidizing agent added may be appropriately set depending on the state of the pulp slurry, but usually, in the case of used paper pulp, a place where mechanical share such as pulper is applied in the pulping process, chemical pulp. In the case of mechanical pulp, it is preferable to add the oxidizing agent concentration in the pulp slurry to 5 ppm or more and 100 ppm or less, preferably 10 ppm or more, to the pulp slurry in a place where mechanical share is applied, such as in the first stage of the cleaning process. , 80 ppm or less is more preferable, and from the viewpoint of economy, it is further preferable to add it so as to be 50 ppm or less.
Further, the oxidizing agent is preferably added so that the residual chlorine amount in the pulp slurry (in the case of monobrolamin, as a residual chlorine amount conversion value) is 0.5 mg / L or more and 30 mg / L or less, 1 mg. It is more preferable to add it so as to be / L or more and 30 mg / L or less, and from the viewpoint of economy, it should be 1 mg / L or more and 10 mg / L or less, or 1 mg / L or more and 5 mg / L or less. It is more preferable to add it.

Further, it is particularly preferable that the oxidizing agent used in the pitch disorder suppressing method of the present invention contains a bound halogen. This is because the amount of residual chlorine in the pulp slurry is maintained and the effect of suppressing pitch obstacles is continuously exhibited.

The description of "residual chlorine amount" in the present invention means "residual chlorine amount conversion value" in the case of monobrolamin.

The pitch dispersant used in the present invention is preferably at least one selected from the group consisting of a surfactant, a cationic polymer and an organic solvent, and two kinds from the viewpoint of reducing aggregation and adhesiveness of pitch components. The above is more preferable.

The surfactant is preferably at least one selected from the group consisting of cationic surfactants, nonionic surfactants and amphoteric surfactants.

Examples of the cationic surfactant include quaternary ammonium compounds such as alkyldimethylbenzylammonium salts and dialkyldimethylammonium salts having an alkyl group having 10 to 18 carbon atoms, and dihydroxyethylalkylamines having 10 to 18 carbon atoms. Be done.
Specifically, decyldimethylbenzylammonium chloride, decyldimethylbenzylammonium bromide, dodecyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium bromide, tetradecyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium bromide, hexadecyldimethylbenzylammonium chloride, Hexadecyldimethylbenzylammonium bromide, octadecyldimethylbenzylammonium chloride and octadecyldimethylbenzylammonium bromide, lauryldimethylbenzylammonium chloride, lauryldimethylbenzylammonium bromide, dihydroxyethylstearylamine, dihydroxyethyloleylamine and the like can be mentioned. The seeds can be used alone or in combination of two or more. Among these, an alkyldimethylbenzylammonium salt having an alkyl group having 12 to 18 carbon atoms, a dihydroxyethylalkylamine having 12 to 18 carbon atoms, and the like are preferable in terms of the effect of improving the dispersibility of the pitch component in the pulp slurry. Alkyldimethylbenzylammonium chloride and dihydroxyethylstearylamine having an alkyl group having 12 to 18 carbon atoms are particularly preferable.

Examples of the nonionic surfactant include ethylene oxide of higher aliphatic amines or adducts of ethylene oxide and propylene oxide, and adducts of ethylene oxide or ethylene oxide and propylene oxide of higher alcohol ethers.

As an adduct of ethylene oxide of higher aliphatic amine or ethylene oxide and propylene oxide, propylene oxide obtained by adding 10 to 30 mol of ethylene oxide to a saturated or unsaturated aliphatic amine having 10 to 20 carbon atoms is used. The addition of 0 to 15 mol is preferable from the viewpoint of the effect of improving the dispersibility of the pitch component, and the addition of 10 to 20 mol of ethylene oxide and the addition of 0 to 5 mol of propylene oxide are more preferable.

Examples of saturated or unsaturated aliphatic amines having 10 to 20 carbon atoms include decylamine, dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, oleylamine, beef tallow alkylamine, and coconut alkylamine. Here, the beef hydrocarbon alkylamine and coconut alkylamine are linear or branched saturated or unsaturated amines having 12 to 20 carbon atoms whose amine is produced from coconut oil, coconut fat, beef fat or the like by a known means. It means that the aliphatic hydrocarbon group of is a mixture of amines (mixed alkylamines) which occupy the main component thereof.

The higher aliphatic amine ethylene oxide or the adduct of ethylene oxide and propylene oxide is specifically an adduct of 20 mol of stearylamine / ethylene oxide and an adduct of beeffat amine / ethylene oxide propylene oxide with an addition ratio of 85/15 (ethylene oxide 31). Morpropylene oxide (4 mol adduct) is particularly preferred.

Ethylene oxide of higher alcohol ether or adduct of ethylene oxide and propylene oxide is a saturated or unsaturated fatty acid having 12 to 18 carbon atoms supplemented with 4 to 50 mol of ethylene oxide, and propylene oxide is 0 to 15. The molar adduct is preferable from the viewpoint of improving the dispersibility of the pitch component, and examples thereof include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ether, and fatty acid ester of polyoxyethylene glycol.

The ethylene oxide of the higher alcohol ether or the adduct of ethylene oxide and propylene oxide is specifically polyoxyethylene lauryl ether, polyoxyethylene tetradecyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene. Oleyl ether, polyoxyethylene octyldodecyl ether, polyoxyethylene laurylphenyl ether, polyoxyethylene tetradecylphenyl ether, polyoxyethylene cetylphenyl ether, polyoxyethylene stearylphenyl ether, polyoxyethylene oleylphenyl ether and polyoxyethylene octyl Dodecylphenyl ether can be mentioned. Of these, the use of polyoxyethylene alkyl phenol ether is preferable, and polyoxyethylene nonyl phenol ether with 10 to 16 mol of ethylene oxide added is particularly preferable.

Examples of the amphoteric surfactant include betaine alkyldimethylaminoacetic acid having a saturated or unsaturated alkyl group having 10 to 18 carbon atoms.
Specifically, decyldimethylaminoacetic acid betaine, dodecyldimethylaminoacetic acid betaine, tetradecyldimethylaminoacetic acid betaine, hexadecyldimethylaminoacetic acid betaine, octadecyldimethylaminoacetic acid betaine, lauryldimethylaminoacetic acid betaine, and stearyldimethylaminoacetic acid betaine. Etc., and in the present invention, one of these can be used alone or in combination of two or more. Among these, betaine lauryldimethylaminoacetic acid and the like are preferable in terms of the effect of improving the dispersibility of the pitch component in the pulp slurry.

Examples of the cationic polymer include water-soluble aluminum compounds, polydialyldimethylammonium salts, epichlorohydrin-dialkylamine condensates, and the like.
Specific examples of the water-soluble aluminum compound include polyaluminum chloride and polyhydroxyammonium chloride.
Specific examples of the polydiallyldimethylammonium salt include polydiallyldimethylammonium chloride, polydiallyldimethylammonium bromide, polydiallyldimethylammonium nitrate, polydiallyldimethylammonium sulfate, and polydiallyl having a molecular weight of 20,000 to 100,000. Examples thereof include dimethylammonium phosphate, and among them, polydiallyldimethylammonium chloride is particularly preferable.
Specific examples of the epichlorohydrin-dialkylamine condensate include an epichlorohydrin dimethylamine condensate having a molecular weight of 10,000 to 200,000 and an epichlorohydrin diethylamine condensate.
In the present invention, one of these can be used alone or in combination of two or more. Among these, polyaluminum chloride and / or polydiallyldimethylammonium chloride having a molecular weight of 20,000 to 100,000 is more preferable in terms of the effect of improving the dispersibility of pitch components in the pulp slurry.

Examples of the organic solvent include higher fatty acid alkylamides, glycols, glycol ethers and dimethyl sulfoxide, tetrahydrofuran and the like.
Specific examples of the higher fatty acid alkylamide include tall oil fatty acid dimethylamide.
Specific examples of the glycol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and the like.
Specific examples of the glycol ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propoxypropanol, and propylene. Examples thereof include glycol monomethyl ether, dipropylene glycol monomethyl ether and tripropylene glycol methyl ether.
In the present invention, one of these can be used alone or in combination of two or more. Among these, tall oil fatty acid dimethylamide, ethylene glycol, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether and the like are preferable in terms of the effect of improving the dispersibility of pitch components in the pulp slurry.

The oxidizing agent and / or pitch dispersant used in the present invention is preferably at least two kinds selected from the group consisting of the oxidizing agent, the surfactant, the cationic polymer and the organic solvent. The preferred combination varies depending on the type of pitch and the composition of the pulp slurry, but the combination of the oxidizing agent and the nonionic surfactant, the combination of the oxidizing agent and the nonionic surfactant and the cationic polymer, or the combination of the oxidizing agent and the cationic polymer is more preferable. preferable. Specifically, as the oxidizing agent, at least one selected from the group consisting of hypochlorite, chlorine dioxide and monochloroamine is preferable, and as a cationic surfactant, lauryldimethylbenzylammonium chloride and / or dihydroxyethylstearylamine Is preferable. As the nonionic surfactant, polyoxyethylene stearylamine with 10 to 30 mol of ethylene oxide and / or polyoxyethylene nonylphenol ether with 10 to 16 mol of ethylene oxide are preferable. As the amphoteric surfactant, betaine lauryldimethylaminoacetate is preferable. As the cationic polymer, polyaluminum chloride and / or polydiallyldimethylammonium chloride having a molecular weight of 20,000 to 100,000 is preferable. As the organic solvent, at least one selected from tall oil fatty acid dimethylamide, ethylene glycol, ethylene glycol monobutyl ether and diethylene glycol monobutyl ether is preferable.

Particularly preferred combinations of at least two pitch dispersants are a combination of polyoxyethylene stearylamine and polyaluminum chloride, a combination of polyoxyethylene stearylamine and tall oil fatty acid dimethylamide, polyoxyethylene stearylamine and tall oil fatty acid dimethyl. Combination of amide and polyaluminum chloride, combination of polyoxyethylene stearylamine and polydiallyldimethylammonium chloride, combination of polyaluminum chloride and ethylene glycol monobutyl ether, combination of polyaluminum chloride and tall oil fatty acid dimethylamide, polyoxyethylene stearylamine And a combination of tall oil fatty acid dimethylamide and polydiallyldimethylammonium chloride.
Preferred combinations of the oxidizing agent and the pitch dispersant include a combination of monochloroamine and polyaluminum chloride, a combination of monochloroamine and tall oil fatty acid dimethylamide and polyaluminum chloride, a combination of monochloroamine and polyoxyethylene stearylamine, and monochloroamine. Combination of tall oil fatty acid dimethylamide and polyoxyethylene stearylamine, combination of sodium hypochlorite and polyaluminum chloride, combination of sodium hypochlorite and tall oil fatty acid dimethylamide and polyaluminum chloride, sodium hypochlorate and Combination of polyoxyethylene stearylamine, combination of sodium hypochlorite and tall oil fatty acid dimethylamide and polyoxyethylene stearylamine, combination of hydrogen peroxide and polyoxyethylene stearylamine, hydrogen peroxide and sodium hypochlorite and Examples thereof include a combination of polyoxyethylene stearylamine, a combination of monochloroamine and diethylene glycol monobutyl ether, a combination of monochloroamine and polyoxyethylene stearylamine and polyaluminum chloride, and a combination of chlorine dioxide and tall oil fatty acid dimethylamide and polyaluminum chloride.

When the pitch dispersant is a surfactant and / or an organic solvent, the total amount of the pitch dispersant added to the pulp slurry in at least one of the pulping step and the preparation step is 1 in terms of pulp. It is preferably .5 kg / t, more preferably 1.0 kg / t, and further preferably 0.5 kg / t from the viewpoint of economy. The lower limit is preferably 0.1 kg / t, more preferably 0.25 kg / t. When the pitch dispersant is a cationic polymer, the total amount added is preferably 3.0 kg / t in terms of the amount of pulp, and the upper limit is more preferably 1.5 kg / t, which is economical. It is more preferably 1.0 kg / t from the point. The lower limit is preferably 0.1 kg / t, more preferably 0.25 kg / t. This is because the pitch dispersant is added to the pulp slurry in the above-mentioned amount, so that the dispersibility of the pitch component in the pulp slurry can be maintained and the enlargement due to the aggregation of the bitch can be prevented.

In the pitch obstacle suppressing method of the present invention, the occurrence of pitch obstacles in the papermaking process is suppressed by controlling the average particle size of the pitch of the pulp slurry in the papermaking process to be less than 150 μm.
As described above, in the papermaking process, the pitch not only adheres to manufacturing equipment such as fan pumps, pipes, chests, wires, felts, and rolls, but also the deposits are peeled off and reattached to paper and pulp. As a result, stains and defects of the formed paper occur, the quality of the paper product is deteriorated, and the generated paper breakage causes obstacles such as a decrease in productivity and workability. Regarding the average particle size of the pitch, a numerical value of 150 μm is a size that can be placed on the paper surface, and if the size is larger than that, the probability of being detected as a defect becomes very high, so that it is one reference value. Therefore, as one of the pitch analysis methods in the papermaking process, the pulp slurry is passed through a mesh wire mesh having an opening of 150 μm.
Therefore, by controlling the size (particle size) of the pitch in the pulp slurry, the state of the pitch in the pulp slurry before being introduced into the papermaking process should be maintained in a state of being dispersed with an average particle size of less than 150 μm. And / or, by maintaining the state of the pitch in the pulp slurry after being introduced into the papermaking process in a state of being dispersed with an average particle size of less than 150 μm, the adhesion of the pitch in the papermaking process is suppressed and the pitch is reduced. Since the pulp fibers are in contact with the pulp fibers in a stably dispersed state, the pitch in the miniaturized state of a specific size is evenly machined onto the paper, and the pitch is discharged outside the papermaking process. Therefore, pitch stains can be prevented, and various pitch obstacles that occur in the papermaking process, such as the generation of defective products due to the enormous pitch adhering to the paper product and the paper breakage, can be suppressed as a whole. Further, the pitch component is drawn into the paper and discharged outside the papermaking process, so that the amount of the pitch component in the white water that is recycled in the entire papermaking process is reduced. That is, the total amount of pitch in the system in the papermaking process can be reduced, and pitch obstacles can be effectively suppressed.
Therefore, the method for suppressing pitch obstacles of the present invention may be used for pulp slurries in a pulping step and / or a preparation step in which the average particle size of the pitch contained in the pulp slurry introduced in the papermaking step is 150 μm or more. preferable. Further, it is preferably used for the pulp slurry in the papermaking process in which the average particle size of the pitch contained in the pulp slurry after being introduced into the papermaking process is 150 μm or more. This is because, as described above, the pitch component having a large pitch particle size causes pitch failure in the papermaking process. Further, the pitch obstacle suppressing method of the present invention includes a pitch size measuring step for measuring the average particle size of the pitch in the pulp slurry introduced in the papermaking process, and the average pitch in the pulp slurry introduced in the papermaking process. When the particle size is 150 μm or more, it is preferable that the oxidizing agent addition step and / or the pitch dispersant addition step is carried out at at least one of the pulping step and / or the conditioning step. The pitch size measurement step may be performed at at least one of the pulping step and the conditioning step, but is preferably carried out in the conditioning step. Further, the pitch obstacle suppressing method of the present invention has a pitch size measuring step for measuring the average particle size of the pitch in the pulp slurry introduced in the papermaking process, and has an average pitch in the pulp slurry introduced in the papermaking process. When the particle size is 150 μm or more, it is preferable that the oxidizing agent addition step and / or the pitch dispersant addition step is carried out at at least one place in the papermaking process. The pitch size measurement step may be performed at at least one place in the papermaking process, but is preferably performed on the upstream side of the inlet.

By the oxidant addition step and / or the pitch dispersant addition step, the pitch component has an average pitch particle size of less than 150 μm in the pulp slurry before being introduced into the papermaking process, but the pitch average particle size. Is preferably less than 120 μm, more preferably less than 77 μm, and even more preferably less than 23 μm.
When the oxidant addition step and / or the pitch dispersant addition step is performed in the papermaking step, the average particle size of the pitch in the pulp slurry introduced in the papermaking step is less than 150 μm, but the average grain size of the pitch is less than 150 μm. The diameter is preferably less than 120 μm, more preferably less than 77 μm, and even more preferably less than 23 μm.

The average particle size of the pitch in the pulp slurry can be measured based on the common general technical knowledge used by those skilled in the art in the technical field to which the present invention belongs. For example, the average of the pitch is averaged by using image analysis as follows. The particle size can be calculated.

The method of measuring the average particle size of the pitch using image analysis will be described below.

(Acquisition of images of pitch particles in aqueous solution)
White water is sampled from the pulp slurry in a beaker or the like so that pulp fibers do not enter. For example, white water may be sampled using a dropper so that pulp fibers do not enter visually, or water may be sampled using centrifugation. Next, the obtained white water is diluted with pure water to an appropriate concentration, and an image of pitch particles is recorded using a device such as a microscope capable of acquiring an image (for example, a fluorescence microscope manufactured by Olympus Corporation). In this case, if the pitch particles are difficult to understand, a dyeing solution for the hydrophobic component is added to stain the pitch component, and then a color image of the pitch particles is recorded using a microscope or the like.

(Calculation method of average grain size of pitch by image analysis)
Using analysis software (Image J / provided by the National Institutes of Health), the pitch is isolated so that the particles can be clearly seen visually, and the average particle size and number of pitches are calculated by image analysis.

The oxidant addition step is performed at least one place in the pulping step and the preparation step, and the pitch dispersant addition step is performed at at least one place in the pulping step and the preparation step, but mechanically with respect to the pulp slurry. It is preferable that this is performed on the pulp slurry on the upstream side of at least one of the devices for sharing. Further, it is preferably performed on the pulp slurry downstream from the pulper step (dissolution step) and / or the deinking step. By adding the oxidizing agent, miniaturization of the pitch component contained in the pulp slurry is promoted. Further, by adding the pitch dispersant, the aggregation of the pitch components is suppressed and the dispersibility is improved. Therefore, the pitch component in the pulp slurry is stably dispersed in a miniaturized state.

Since the pulper step is the most upstream step of the pulping step, by adding an oxidizing agent in this step, it is possible to promote the miniaturization of the pitch and further reduce the average particle size of the pitch. .. Further, by adding the pitch dispersant in the pulping step, the pitch in the miniaturized state can be stably dispersed, the agglomeration of the pitch can be prevented, and the enlargement can be suppressed.
Further, in the deinking step, a part of the pitch component is discharged to the outside of the pulping step, but the pitch component remains in a certain amount or more in the pulp slurry after the deinking step. Therefore, by carrying out the oxidizing agent addition step and / or the pitch dispersant addition step on the pulp slurry downstream of the deinking step, the pitch component can be miniaturized again, and / or the pitch component can be added. It can be stably dispersed and aggregation and enlargement can be suppressed. By carrying out the oxidant addition step and / or the pitch dispersant addition step in such a step, pitch obstacles in the papermaking step can be more effectively prevented.
Further, it is preferable that the oxidizing agent addition step and / or the pitch dispersant addition step is performed at at least one place in the pulping step and at least one place in the conditioning step. By performing the oxidant addition step and / or the pitch dispersant addition step in the pulping step, the pitch component contained in the pulp slurry is miniaturized upstream of the papermaking process, and further, the step is also performed in the preparation step. This is because it is possible to suppress the enlargement of the miniaturized pitch component and promote further miniaturization.

Further, when the oxidant addition step and / or the pitch dispersant addition step is performed at at least one place in the papermaking process, the upstream side of at least one of the devices for mechanically sharing the pulp slurry in the papermaking process. It is preferably performed on the pulp slurry of. Specifically, it is preferably performed on the pulp slurry on the upstream side of the fan pump. By adding the oxidizing agent, miniaturization of the pitch component contained in the pulp slurry is promoted. Further, by adding the pitch dispersant, the aggregation of the pitch components is suppressed and the dispersibility is improved. Therefore, the pitch component in the pulp slurry is stably dispersed in a miniaturized state.

When adding an oxidizer and pitch dispersant in the papermaking process, as an example, the oxidizer is added to the pulp slurry on the upstream side of the fan pump and circulated from the white water pit under the wire to be used as inlet concentration adjusting water. There is a method of adding a pitch dispersant to the white water to be produced. The pitch component brought into the papermaking process after obtaining the conditioning process from the pulping process becomes fine particles when an oxidizing agent is added and stirred by a fan pump. Furthermore, the fine pitch components that come into contact with the pitch dispersant at the inlet and come into contact with the pitch dispersant when the paper is made at the wire part pass through the white water pit under the wire and circulate in the system from the collecting tank. However, due to the effect of the pitch dispersant, the pitch size is kept small, so that pitch failure does not occur in the system.

The pitch dispersant addition step is preferably carried out on a pulp slurry having a residual chlorine concentration of 0.5 to 30 mg / L, and may be carried out on a pulp slurry having a residual chlorine concentration of 1 to 10 mg / L. More preferred. By adding the pitch dispersant to the pulp slurry having a specific residual chlorine concentration, it is possible to suppress the aggregation of the pitch in the miniaturized state and uniformly disperse the pitch in the miniaturized state in the pulp slurry. As a result, pitch obstacles in the papermaking process can be suppressed.

Further, when the pitch disorder suppressing method of the present invention comprises the above-mentioned oxidizing agent addition step and the above-mentioned pitch dispersant addition step, and the pitch dispersant is added to a pulp slurry having a residual chlorine concentration of 0.5 to 30 mg / L, oxidation occurs. The agent is preferably at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide and bound halogen. More preferably, it is a bonded halogen. Further, the pitch dispersant addition step is preferably located on the downstream side of the oxidizing agent addition step.

Further, the pitch disorder suppressing method of the present invention comprises the above-mentioned oxidant addition step and the above-mentioned pitch dispersant addition step, and is composed of hydrogen peroxide, hypochlorite, chlorite and chlorine dioxide as oxidants. When at least one selected is used, it is preferable that the oxidant addition step and the pitch dispersant addition step are carried out at the same location in at least one of the pulping step and the preparation step. Hydrogen peroxide, hypochlorite, chlorite and chlorine dioxide are consumed when added to the pulp slurry and promote pitch miniaturization, but at the same time, by adding a pitch dispersant, miniaturization This is because the pitch of the state can be effectively dispersed and the miniaturized state of the pitch can be maintained.

Further, the above-mentioned oxidant addition step and / or pitch dispersant addition step may be carried out by continuous addition or intermittent addition, but is preferably carried out by continuous addition.

Further, in the present invention, continuous addition means continuous supply, even when the pitch dispersant and / or the oxidizing agent is continuously supplied to the pulp slurry and the supply and stop are repeated. If the downtime is less than 30 minutes, it will be continuously supplied.

In the pitch obstacle suppressing method of the present invention, the oxidizing agent addition step and / or the pitch dispersant addition step is preferably carried out on a pulp slurry having a pulp concentration of 0.5 to 50%, and the pulp concentration is 2 More preferably, it is carried out on pulp slurries of 0 to 20%.

FIG. 1 is a block diagram illustrating a waste paper pulping step for explaining one embodiment of the present invention.
The used paper raw material is made into a pulp slurry by the pulper 1, dehydrated by the screw press 2, and then stored in the aging tower 3. Next, the pulp slurry sent from the aging tower 3 passes through the double separator 4, is deinked by the fall washer 5 and the rotary screen 6, and is stored in the stock chest 7a. After that, the pulp slurry is bleached in the hydrogen peroxide-exposed tower 8, washed and dehydrated by the washer 9 and the thickener 10, and stored in the completed chest 7b. The white water discharged in each process is collected by the white water recovery line 12 and collected in the white water pit 11.
The white water collected in the white water pit 11 passes through the white water supply line 13 for supplying white water to the pulper 1, the flow path connecting the pulper 1 and the aging tower 3, the flow path connecting the bleaching tower 8 and the washer 9, and the like. , Supplied to the used paper pulp manufacturing process and reused.

As described above, the pulping process generally has a plurality of washing / dehydrating processes, such as a pulper, a refiner, a screw press, a double separator, a selection screen, a rotary screen, a washer, a thickener, and a fan pump. In the equipment, the pulp slurry is agitated.
In the pitch obstacle suppressing method of the present invention, it is preferable to carry out the oxidizing agent addition step and / or the pitch dispersant addition step on the pulp slurry on the upstream side of the stirring step on the upstream side of the drainage line. This is because the pitch component in the pulp slurry is miniaturized by the oxidizing agent, aggregation is suppressed by the pitch dispersant, and the dispersibility is improved, so that the pitch component is discharged together with white water in the subsequent drainage line.

Further, in the pitch obstacle suppressing method of the present invention, it is preferable to further carry out the above-mentioned oxidizing agent addition step and / or pitch dispersant addition step on the pulp slurry on the downstream side of the discharge line. Further miniaturization of the pitch component remaining in the pulp slurry and / or suppression of aggregation causes the pitch component to be stably dispersed in the miniaturized state, and more effective pitch obstacles in the subsequent papermaking process. This is because it can be prevented.

Further, it is more preferable that the oxidant addition step and / or the pitch dispersant addition step is performed at at least one place for each white water loop. Here, the white water loop is a white water recirculation system formed by collecting the white water discharged from the raw material line in the white water pit and supplying the white water collected in the white water pit to the raw material line. Good, one white water loop is formed for one white water pit. When there are multiple white water supply lines from one white water pit, the white water recirculation system formed by the most upstream side white water supply line that supplies white water from the white water pit to the most upstream side of the raw material line is called a white water loop. The white water supply line branching from the most upstream side white water supply line is also included in a part of the white water loop.

Further, in another aspect of the pitch obstacle suppressing method of the present invention, the step of adding the oxidizing agent and / or the step of adding the dispersant is provided so that the average particle size of the pitch contained in the pulp slurry is less than 150 μm. The oxidant addition step and / or the pitch dispersant addition step is provided so that the content of the pitch having a particle size of less than 150 μm is 50% or more with respect to the total amount of the pitch contained in the pulp slurry. It may be that. As described above, when the particle size of the pitch is 150 μm or more, a pitch disorder in the papermaking process and a pitch disorder in the entire papermaking process are likely to occur. Therefore, the pitch component having a pitch particle size of less than 150 μm is the total pitch amount. This is because the effect of the present invention can be obtained even when the content is 50% or more.

The amount of the pitch component having a pitch particle size of less than 150 μm can be measured based on the common general technical knowledge commonly used by those skilled in the art to which the present invention belongs. For example, the pulp slurry before being introduced into the papermaking process and / or the pulp slurry after being introduced into the papermaking process is taken, and the pitch in the white water collected so as not to contain pulp fibers is measured by image analysis. This makes it possible to calculate the amount and proportion of pitch components less than 150 μm.

In this case, the pitch component having a particle size of less than 150 μm is preferably 60% or more, more preferably 70% or more, based on the total amount of the pitch component in the pulp slurry. Further, the particle size of the pitch of 50% or more with respect to the total pitch is preferably less than 120 μm, more preferably less than 77 μm, and further preferably less than 23 μm.

According to the pitch obstacle suppressing method of the present invention, pitch obstacles in the papermaking process can be prevented.

FIG. 1 is a block diagram illustrating a waste paper pulping step for explaining one embodiment of the present invention. FIG. 2 is a graph showing the amount of hydrophobic substances (pitch) contained in the pulp slurry in the seed box in the papermaking process in Examples 31 and 32 and Reference Example 7. FIG. 3 is a graph showing the amount of hydrophobic substances (pitch) in white water in the papermaking process in Examples 31 and 32 and Reference Example 7. FIG. 4 is a flow chart illustrating a pulping process and a preparation process of the papermaking process in Test Example 8.

The present invention will be described with reference to the following examples, comparative examples and reference examples, but the present invention is not limited thereto. In the following examples, the miniaturization of the pitch size may be expressed as the miniaturization of the pitch size and the miniaturization of the pitch.

[Test Example 1]
(Examples 1 to 7 and Comparative Example 1)
1 L of used paper pulp slurry mainly composed of ethylene-vinyl acetate copolymer was weighed as a pitch component, and this was used as a sample.
Each drug having the concentration shown in Table 1 below was added to the obtained sample, and the mixture was stirred at room temperature with a tabletop pulper (manufactured by Kumagai Riki Kogyo Co., Ltd.) for 3 minutes (2000 rpm) to obtain a sample containing the drug.
Next, the obtained sample containing the drug was kept warm in a warm bath at 35 ° C., and gently stirred for 72 hours assuming a pulp slurry flowing through the pipe using a three-one motor.
Next, the average particle size of the pitch in the sample after stirring for 72 hours was measured using an automatic cell counter (Countess II FL) manufactured by Thermo Fisher. The measurement conditions of the cell counter were 10 or more particles of 10 to the 6th power and 100% fluorescence. The measurement conditions of the cell counter are all the same in the following test examples. The measurement results are shown in Table 1 below. When the unit of the amount of the drug added in the table below is (kg / T), the amount added to the pulp is shown, and when the unit of the amount added is (ppm), the amount added to the pulp slurry is shown. ing. In addition, the classification of the agents added in the test is shown as A for the pitch dispersant and B for the oxidizing agent.

The liquid concentrations of the chemicals used in Examples 1 to 12 and Reference Examples 1 to 6 below are as follows. In each test, the addition concentration shown in the table is added so as to be the active ingredient concentration.
Monochrome lamin is produced by a known method (for example, the method described in JP-A-2017-53054), and then diluted with pure water as appropriate to adjust the drug concentration to the concentration shown in Table 1 below. Added.
20 mol adduct of polyoxyethylene stearylamine / ethylene oxide (30% aqueous solution)
Tall oil fatty acid dimethylamide (95% aqueous solution)
Polyaluminum chloride (32% aqueous solution)
Hydrogen peroxide (35% aqueous solution)

From Examples 1 to 4, it was found that the pitch size can be made finer when the surfactant, the cationic polymer or the organic solvent which is the pitch dispersant is used alone or when the oxidizing agent is used alone for the sample. confirmed.
Furthermore, from Examples 5 to 7, a more excellent pitch miniaturization effect was confirmed by using a combination of an oxidizing agent and a pitch dispersant, and a combination of a cationic polymer as a pitch dispersant and a surfactant. ..

[Test Example 2]
(Examples 8 to 10, Comparative Examples 2 and Reference Examples 1 to 4)
A waste paper pulp slurry mainly composed of an acrylic acid ester polymer was weighed to a basis weight of 100 g / m ² as a pitch portion, and this was used as a sample.
Each drug having the concentration shown in Table 2 below was added to the obtained sample, kept warm in a warm bath at 40 ° C., stirred with a stirrer for 1 hour, and the drugs according to Examples 8 to 10 and Reference Examples 1 to 4. And a drug-free sample according to Comparative Example 2 were obtained.
Next, the pitch size of each of the obtained samples after being left to stand in a cool and dark room at 4 ° C. for 1 week was measured using an automatic cell counter (Countess II FL) manufactured by Thermo Fisher. Table 2 below shows the measurement results of the pitch miniaturization rate based on the pitch size without the addition of chemicals after one week.

When the pitch size was confirmed one week after the treatment, it was confirmed that the pitch size was enlarged due to the aggregation of the pitch only with the surfactant or the oxidizing agent. It is considered that this is because the pitch size became larger than that in the case where no chemical was added because the agglomeration occurred due to the influence of the inorganic components present in the waste paper pulp slurry after being left to stand for one week. In the actual machine, the pulp slurry is not allowed to stand for a week and does not grow to the extent that pitch failure occurs as in this test, and the test results are under stricter conditions. On the other hand, from Examples 8 to 10, it was confirmed that an excellent pitch miniaturization effect can be continuously obtained by using the pitch dispersant (surfactant) and the oxidizing agent in combination.

[Test Example 3]
(Examples 11 and 12, Reference Examples 5 and 6 and Comparative Example 3)
The same operation as in Test Example 2 was performed except that each drug having the concentration shown in Table 3 below was used, and the sample containing the drugs according to Examples 11 and 12 and Reference Examples 5 and 6 and the drug according to Comparative Example 3 were used. An additive-free sample was obtained. Next, using each of the obtained samples, papermaking was performed to prepare a sheet. The obtained sheet was extracted with an organic solvent, and the amount of pitch contained in the sheet was measured. Then, based on the sheet pitch amount prepared from the drug-free sample according to Comparative Example 3, the rate at which the pitch decreased with the addition of the drug was defined as the pitch cleaning rate on the sheet. Further, the pitch miniaturization rate was measured by using an automatic cell counter to measure the pitch size after each of the above samples was left to stand and stored in a cool and dark room at 4 ° C. for 1 week in the same manner as in Test Example 2. The measurement results are shown in Table 3 below.

When the pitch size was confirmed one week after the treatment, it was confirmed that the pitch size was enlarged due to the aggregation of the pitch with only the surfactant, as in the result in Test Example 2. On the other hand, from Examples 11 and 12, it was confirmed that an excellent pitch miniaturization effect can be continuously obtained by using the pitch dispersant (surfactant) and the oxidizing agent in combination.
It was also confirmed that an excellent cleaning effect can be obtained by using the pitch dispersant and the oxidizing agent in combination with respect to the amount of pitch contained in the obtained sheet.

[Test Example 4]
(Examples 13 to 22 and Comparative Example 4)
1 L of used paper pulp slurry mainly composed of ethylene-vinyl acetate copolymer was weighed as a pitch component, and this was used as a sample. The same test operation as in Test Example 1 was performed in the sample except that each drug having the concentration shown in Table 4 below was added to the obtained sample instead of adding each drug having the concentration shown in Table 1 below. The average particle size of the pitch was measured using an automatic cell counter. The measurement results are shown in Table 4 below.

The liquid concentration of each drug used in the following examples is as follows. In each test, the addition concentration shown in the table is added so as to be the active ingredient concentration.
Chlorine dioxide was produced by a known method (for example, the method described in Japanese Patent No. 5879596) and then appropriately diluted with pure water to adjust the concentration of the chemicals shown in Table 4 below and added.
10 mol adduct of polyoxyethylene stearylamine / ethylene oxide (purity 100%)
20 mol adduct of polyoxyethylene stearyl ether / ethylene oxide (purity 100%)
Sodium hypochlorite (12% aqueous solution)
Chlorine dioxide ethylene glycol monobutyl ether (purity 99% or more)
Ethylene glycol (purity 99% or higher)

From Examples 13 to 18, it was confirmed that the pitch size can be made finer even when a surfactant, a cationic polymer or an organic solvent, which is a pitch dispersant, is used alone for the sample.
Further, from Examples 19 to 22, more excellent pitch miniaturization effect was confirmed by using a combination of an organic solvent and a cationic polymer as pitch dispersants and a combination of an oxidizing agent, a cationic polymer and a surfactant.

[Test Example 5]
(Examples 23 to 27 and Comparative Example 5)
Unbleached kraft pulp containing mainly rosin as a natural pitch in the pitch portion was diluted to 0.3% with tap water to obtain a pulp slurry. The pulp slurry was adjusted to pH 4 with hydrochloric acid and used as a sample. After adding each drug having the concentration shown in Table 5 below to 1 L of the obtained sample, the mixture was stirred at 150 rpm for 72 hours using a three-one motor while keeping warm in a warm bath at 40 ° C.
Next, the average particle size of the pitch in each sample after stirring for 72 hours was measured using an automatic cell counter (Countess II FL) manufactured by Thermo Fisher, as in Test Example 1. The measurement results are shown in Table 5 below.

From Examples 23 to 25, it was confirmed that the pitch can be made finer even when the pitch dispersant and the oxidizing agent are used alone with respect to the natural pitch. Further, from Examples 26 and 27, a more excellent pitch miniaturization effect was confirmed even in the combination of the pitch dispersant and the oxidizing agent.

[Test Example 6]
(Example 28 and Comparative Example 6)
A paperboard raw material containing an ethylene-vinyl acetate copolymer as a pitch component was diluted with tap water to 0.3% to prepare a pulp slurry, which was used as a sample. A sample in which monochrome lamin was added at 15 ppm to a slurry to 300 mL of the obtained sample was used as the sample according to Example 28. A sample to which monochrome lamin was not added was used as the sample according to Comparative Example 6. After stirring each sample at 600 rpm for 3 minutes using a three-one motor, put it in a plastic bottle with a capacity of 100 mL, seal it, and use an automatic cell counter to measure the average particle size of the pitch after 1 week at 150 rpm and 30 ° C in a rotary incubator. Was measured. The measurement results are shown in Table 6 below.

From Example 28, it was confirmed that the pitch can be made finer by adding an oxidizing agent even if the pitch size is large.

[Test Example 7]
(Examples 29 and 30 and Comparative Example 7)
Corrugated cardboard waste paper mainly containing an ethylene-vinyl acetate copolymer as a pitch component was diluted to 0.3% with tap water to prepare a pulp slurry, which was used as a sample. Two samples in which monochrome lamin was added at 15 ppm to the slurry were prepared in 300 mL of the obtained sample, and used as the samples according to Examples 29 and 30. A sample to which monochrome lamin was not added was used as the sample according to Comparative Example 7. After gently stirring each sample with a stirrer for 15 minutes, a dispersant was added to the sample according to Example 30 at 0.5 kg / t of pulp. After gently stirring each sample with a stirrer for another 30 minutes, the average particle size of the pitch was measured using an automatic cell counter. The measurement results are shown in Table 7 below.

From Example 29, the pitch size can be miniaturized even when the oxidizing agent is used alone, but from the results of Example 30, when the oxidizing agent and the surfactant are used in combination, the addition locations of both agents are set to be farther away from each other. It was confirmed that the pitch size can be further miniaturized even in the test assuming the above.

[Test Example 8]
(Examples 31 and 32 and Reference Example 7)
In the papermaking process in the production of toilet paper at a certain paper mill shown in FIG. 4, the pitch in the papermaking process when a pitch dispersant (surfactant type or cationic polymer type) is added to any of the pulping step and the preparation step. The size was measured. The purpose of this test is to confirm in the actual papermaking process how the pitch amount of a specific size in the papermaking process changes depending on the place where the chemical is added, and the test is conducted from the start of the test to the 5th day. Reference Example 7, the test 13 to 24 days after the start of the test was designated as Example 31, and the test 36 to 62 days after the start of the test was designated as Example 32.

(Reference example 7)
From the start of the test to the 5th day, a cationic polymer-based pitch dispersant was added to the overall chest 51 in the papermaking process at a rate of 1.0 kg / t per pulp.
(Example 31)
On the 13th to 24th days from the start of the test, a surfactant-based pitch dispersant was added to the tank 43 provided at the outlet of the aging tower 42 in the papermaking process at 0.5 kg / t against pulp, and the cationic polymer was added to the comprehensive chest 51. The system pitch dispersant was added at 0.5 kg / t per pulp.
(Example 32)
On the 36th to 62nd days from the start of the test, a surfactant-based pitch dispersant was added to the tank 43 provided at the outlet of the aging tower 42 in the papermaking process at 0.5 kg / t against pulp, and the cation was added to the comprehensive chest chest 51. A polymer-based pitch dispersant was added at 0.3 kg / t.

(Measurement of the amount of hydrophobic substance (pitch) of a specific size in the papermaking process)
Circulated white water and pulp slurry of a seed box were collected from the papermaking process of the papermaking process in the production of toilet paper at a certain paper mill, fractionated with a mesh having a diameter of 150 μm or a diameter of 23 μm, and the filtrate was collected. 6 μL of 0.01% dye was added to 3 mL of the filtrate and stirred for 30 seconds to stain the hydrophobic substance (pitch). The fluorescence intensity was measured using a hydrophobicity tester (Handheld Fluorometer manufactured by Turner Designs) and used as the amount of hydrophobic substance (pitch).
The seed box is a chest provided downstream of the general chest 51 and before the pulp concentration adjusting water is added to send the pulp slurry to the inlet. As an example, it is installed in front of the fan pump. (Not shown in FIG. 4)
The daily fluctuations in the amount of hydrophobic substance less than 150 μm and the amount of hydrophobic substance less than 23 μm in the filtrate of the pulp slurry in white water and the seed box are shown in FIGS. 2 and 3.

From FIGS. 2 and 3, in the actual papermaking process, the tank provided at the outlet of the aging tower 42 in addition to the general chest 51 is compared with the reference example 7 in which the pitch dispersant is added only to the general chest 51. It was confirmed that the amount of the hydrophobic substance (pitch) having a pitch size of less than 150 μm increased in the pulp slurry and in the white water in the papermaking process when the pitch dispersant was also added to 43. Furthermore, it was confirmed that the amount of hydrophobic substances (pitch) less than 23 μm increased. From this result, the hydrophobic substance (pitch) in the papermaking process is obtained by adding the pitch dispersant to both the pulping process and the conditioning process, rather than adding the pitch dispersant only to the general chest in the conditioning process. Was confirmed to be finer. This is because the separator 44 in the pulping process has a mechanical share, and therefore, the hydrophobic substance (pitch) in the pulp slurry is effectively miniaturized by adding the pitch dispersant on the upstream side of the separator 44. Further, it is considered that the miniaturized state of the hydrophobic substance (pitch) was maintained by adding the pitch dispersant to the general chest in the preparation step. Due to this effect, the adhesion of pitch in the system was reduced, and the number of times the paper machine that required cleaning was stopped was clearly reduced. In addition, the number of defects generated was also reduced by reducing the transfer of felt and the like into the system due to the weakening of the adhesive strength of the pitch due to the miniaturization of the pitch.

1 Pulper 2 Screw Press 3 Aging Tower 4 Double Separator 5 Fall Washer 6 Rotary Screen 7a Stock Chest 7b Completed Chest 7c Chest 8 Hydrogen Peroxide Exposed Tower 9 Washer 10 Thickener 11 White Water Pit 12 White Water Recovery Line 13 White Water Supply Line 41 Pulper 42 Aging Tower 43 Tank 44 Separator 45 Fall Washer 46 Screen 47 Screw Press 48 Fine Screen 49 Washer 50a Tank a
50b tank b
51 Comprehensive chest

Claims (10)

A pitch failure suppressing method that controls the size of the pitch contained in the pulp slurry in the pulping process and / or the preparation process to suppress the occurrence of pitch failure in the papermaking process.
An oxidant addition step of adding an oxidant to the pulp slurry at at least one of the pulping step and the preparation step so that the average particle size of the pitch contained in the pulp slurry is less than 150 μm, and / or A method for suppressing pitch obstacles, which comprises a pitch dispersant addition step of adding a pitch dispersant to at least one pulp slurry in the pulping step and the preparation step. A pitch failure suppressing method that controls the size of the pitch contained in the pulp slurry in the papermaking process and suppresses the occurrence of pitch failure in the papermaking process.
An oxidant addition step of adding an oxidant to at least one pulp slurry in the papermaking process and at least one of the papermaking steps so that the average particle size of the pitch contained in the pulp slurry is less than 150 μm. A method for suppressing pitch obstacles, which comprises a pitch dispersant addition step of adding a pitch dispersant to the pulp slurry of the above. A pitch failure suppressing method for controlling the size of the pitch contained in the pulp slurry in the pulping step and / or the preparation step and the papermaking step to suppress the occurrence of pitch failure in the papermaking step.
The first oxidizing agent is added to at least one pulp slurry in the pulping step and the preparing step so that the average particle size of the pitch contained in the pulp slurry in the papermaking step is less than 150 μm. An oxidant addition step and / or a first pitch dispersant addition step for adding a first pitch dispersant to at least one pulp slurry in the pulping step and the preparation step, further comprising: A second oxidant addition step of adding a second oxidant to at least one pulp slurry in the papermaking process and / or adding a second pitch dispersant to at least one pulp slurry in the papermaking process. A method for suppressing pitch obstacles, which comprises a second pitch dispersant addition step. The pitch disorder suppressing method according to claim 1 or 2, wherein the oxidizing agent is at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide, hydrogen peroxide, and bound halogen. .. Claim 3 that the first oxidizing agent and the second oxidizing agent are at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide, hydrogen peroxide, and bound halogen. The pitch obstacle suppression method described in 1. The pitch obstacle suppressing method according to claim 1, 2 or 4, wherein in the pitch dispersant addition step, the pitch dispersant is added to a pulp slurry having a residual chlorine concentration of 0.5 mg / L or more and 30 mg / L or less. In claim 3 or 5, in the first pitch dispersant addition step and the second pitch dispersant addition step, the pitch dispersant is added to the pulp slurry having a residual chlorine concentration of 0.5 mg / L or more and 30 mg / L or less. The pitch obstacle suppression method described. Claim 1, which comprises a step of adding an oxidant and a step of adding a pitch dispersant, wherein the oxidant is at least one selected from the group consisting of hypochlorite, chlorite, chlorine dioxide and bound halogen. The pitch obstacle suppressing method according to 2, 4 or 6. The pitch obstacle suppressing method according to claim 1, 2, 4, 6 or 8, wherein the pitch dispersant is at least one selected from the group consisting of a surfactant, a cationic polymer and an organic solvent. The pitch obstacle suppressing method according to claim 3, 5 or 7, wherein the first and second pitch dispersants are at least one selected from the group consisting of a surfactant, a cationic polymer and an organic solvent.

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