JP2020133024A - Method for producing used paper pulp and used paper pulp - Google Patents

Abstract

To provide a method for producing used paper pulp from a pulp material containing used paper containing gypsum and used paper containing an adhesive, and to provide used paper pulp.SOLUTION: A method for producing the waste paper pulp from a waste paper pulp raw material 11 comprises: a disaggregation step of disaggregating the waste paper pulp raw material 11, in which waste paper 10 containing a gypsum component and waste paper containing an adhesive are mixed, to make it a pulp turbid liquid; and a separation step of separating and removing the gypsum component with the adhesive from the pulp turbid liquid to obtain the residue, where the residue is the waste paper pulp. Also provided is a used paper pulp.SELECTED DRAWING: Figure 1

Description

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

In recent years, the reuse of used paper pulp has been regarded as important from the viewpoint of environmental protection, especially resource recycling. As a raw material for used paper pulp, used paper such as newspapers, leaflets, magazines, and information recording paper has been mainly used conventionally.

Of these waste papers, so-called difficult-to-treat waste paper, which is evaluated as a contraindicated item specified in the waste paper standard quality standard of the Waste Paper Recycling Promotion Center, is used for deterioration of the quality of recycled waste paper pulp and in the papermaking process. It has not been used as the main raw material for used paper pulp because it causes troubles such as paper breaks.
Among the difficult-to-treat waste papers, the waste paper containing gypsum (gypsum-containing waste paper) and the waste paper having adhesive (adhesive paper) form spots on the paper surface when calcium or adhesive derived from gypsum is mixed with the waste paper pulp. It has not been used as a raw material for waste paper pulp because it causes adhesion between papers.

Therefore, difficult-to-treat waste paper such as gypsum-containing waste paper and adhesive paper has been mainly disposed of as industrial waste.

In order to promote the recycling of useful used paper in recent years and to effectively use the collected used paper in paper, it is desired to develop a technique for recycling these used paper as a raw material for used paper pulp.

Based on such a background, Patent Document 1 discloses an invention for removing a sticky substance contained in a difficult-to-treat waste paper, particularly an adhesive paper. According to the present invention, a sticky substance remover is added to a process for regenerating used paper to reduce the stickiness of the sticky substance, and the sticky substance is efficiently removed to produce high-quality waste paper pulp. There is a concern that the generation of bubbles caused by the substance remover may cause a decrease in operability and a decrease in the quality of the obtained paper product.

Japanese Unexamined Patent Publication No. 2003-20584

A main problem to be solved by the present invention is to provide a method for producing waste paper pulp from a pulp raw material containing waste paper containing gypsum and waste paper containing an adhesive, and providing waste paper pulp.

<Means according to claim 1>
It is a method of producing waste paper pulp from waste paper pulp raw materials.
Waste paper, which is a mixture of waste paper containing gypsum and waste paper containing adhesive, is dissociated into a pulp turbid liquid.
A separation step of separating and removing gypsum to which sticky substances have adhered from the pulp turbid liquid to obtain a residue, and
With
The balance is used as waste paper pulp.
A method for producing used paper pulp.

When the waste paper pulp raw material, which is a mixture of waste paper containing gypsum and waste paper containing adhesives, is dissociated in the dissociation step, the gypsum is released from the waste paper containing gypsum. In addition, the sticky substance released from the used paper containing the sticky substance is refined in the pulp turbid liquid and becomes present in large numbers. Although the cause is not clear, this finely divided adhesive adheres to the released gypsum. Then, a large number of finely divided adhesives are attached to the adhesives attached to the gypsum, and the adhesives are granulated. Next, in the separation step, the gypsum component to which the sticky substance is attached and enlarged is separated and removed to obtain a residue, and used paper pulp is obtained from this residue. This has the effect that waste paper pulp can be produced from both waste papers, which have been regarded as difficult-to-treat waste papers, that is, waste paper containing gypsum and waste paper containing an adhesive.

<Means according to claim 2>
The used paper pulp raw material contains 0.1 to 10% by mass of used paper containing gypsum and 0.1 to 5% by mass of used paper containing an adhesive.
The method for producing used paper pulp according to claim 1.

When the used paper pulp raw material contains 0.1 to 10% by mass of used paper containing gypsum and 0.1 to 5% by mass of used paper containing adhesive, the gypsum content is efficiently released from the used paper containing gypsum by dissociation. Gypsum. In addition, the sticky substance is efficiently released from the used paper containing the sticky substance. Then, it has an effect that the released gypsum component and the adhesive component are easily adhered to each other.

<Means according to claim 3>
An ion sequestering agent is added to at least one of the disintegration step and the separation step.
The method for producing used paper pulp according to claim 1 or 2.

If a large amount of calcium ions are dissolved in the pulp turbid liquid, the calcium content is scaled in the manufacturing process of used paper pulp and adheres to the manufacturing equipment, which adversely affects the operation of the manufacturing equipment. In addition, when the manufactured paper is stored for a long period of time, it may cause spots on the paper product or foreign matter to adhere to the paper product. By adding an ion sequestering agent, the concentration of calcium ions dissolved in the pulp turbid liquid can be prevented from becoming higher than a predetermined value. As a result, it has the effect of suppressing scaling and suppressing the adhesion of spots and foreign substances generated on the paper.

<Means according to claim 4>
The used paper containing the gypsum content is obtained by crushing the gypsum to which the paper is attached.
The fine gypsum generated when the gypsum is crushed is put into at least one of the disintegration step and the separation step.
The method for producing used paper pulp according to any one of claims 1 to 3.

The gypsum to which paper is attached is not particularly limited, but gypsum with paper or gypsum board used as a building material can be used as an example. When the gypsum to which these papers are attached is crushed, fine gypsum is generated. This fine gypsum contains powdery or granular gypsum, and by adding this fine gypsum to at least one of the disintegration step and the separation step, the gypsum content contained in the pulp turbid liquid (white water). The total amount of gypsum can be increased, and more gypsum with sticky substances is produced in the pulp turbid liquid. As a result, it has the effect that more gypsum and sticky substances are separated and removed in the separation step.

<Means according to claim 5>
A pulp turbid liquid made of a waste paper pulp raw material obtained by mixing 0.1 to 10% by mass of waste paper containing gypsum and 0.1 to 5% by mass of waste paper containing an adhesive is used as a raw material.
The amount of gypsum is 30 mL / 100 g or more.
Waste paper pulp characterized by that.

The respective concentrations (mass%) of the used paper containing gypsum and the used paper containing adhesive are mixed with the used paper pulp raw material in these ranges, and the gypsum content is 30 mL / 100 g or more in oil absorption to make pulp. Adhesive substances adhere to the gypsum released in the turbid liquid. Since the gypsum component to which the sticky substance is attached can be easily removed from the production flow system, it has the effect of producing high-quality waste paper pulp.

<Means according to claim 6>
Freeness is 360 mL-580 mL,
The specific burst strength is 14 (N · cm ² ) × 100 / (g / m ² ) to 30 (N · cm ² ) × 100 / (g / m ² ).
Specific ring strength is ^{132N · m 2 / g · 100~206N} · m 2 / g · 100,
The ash content is 10.0% to 25.0%,
The 6-cut residue is 0.1% to 6.0%,
The used paper pulp according to claim 5.

The used paper pulp of the present invention is of good quality with the gypsum content removed.

According to the present invention, waste paper pulp can be produced from waste paper pulp raw materials containing waste paper containing gypsum and waste paper containing adhesives, and high-quality pulp from which gypsum and adhesives are efficiently removed. Become.

It is a flow chart of the manufacturing method of used paper pulp. It is a figure of the solubility of calcium sulfate. It is a top view of a cleaner. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG.

A mode for carrying out the present invention will be described. The embodiment of the present invention is an example of the present invention.

The present invention aims at recycling adhesive paper and gypsum-containing waste paper, which have been difficult to recycle as contraindicated products in the past. Conventionally, adhesive paper and gypsum-containing waste paper correspond to so-called difficult-to-treat waste paper, which is evaluated as a contraindicated item specified in the waste paper standard quality standard of the Waste Paper Recycling Promotion Center, and was not recycled as it is. .. In the present invention, gypsum-containing waste paper and adhesive paper are mixed and processed in the process of producing waste paper pulp. Then, the gypsum content is released from the gypsum-containing waste paper. In addition, the sticky substance is released from the sticky paper. The sticky substance released from the adhesive paper adhered to the particulate gypsum content released from the gypsum-containing waste paper, and the gypsum component to which the adhesive substance adhered was removed from the manufacturing process to adhere to the gypsum component. Adhesive substances can also be easily removed. According to the present invention, adhesive paper and gypsum-containing waste paper can be recycled as waste paper pulp, and resources can be effectively utilized.

(Adhesive paper)
The adhesive paper in question in the present invention is a paper to which an adhesive or an adhesive used in the printing, processing, wrapping stage, etc. of the paper is attached. Examples of adhesives include pressure-sensitive adhesives and pressure-sensitive adhesives such as adhesive tapes attached to pressure-sensitive adhesive paper (so-called tack paper), glue for envelopes and paper bags, and spine glue for forms. Can be done. In the production of used paper pulp, most of the sticky substances attached to the manufacturing equipment / manufacturing equipment and manufactured products are derived from these.

When the raw material of used paper pulp is dissociated by a dissociation device called a pulper, if the adhesive paper is mixed, the adhesive substance adhering to the adhesive paper is released and becomes a finely divided adhesive substance. The liberated fine adhesives aggregate with each other to form adhesives having a large particle size, and when waste paper pulp is formed in a state where the adhesives are mixed, waste paper pulp containing the adhesives is produced. When paper products are manufactured using this waste paper pulp as a raw material for paper making, appearance defects such as dust occur in the paper products, or the raw paper making material adheres to the paper machine or dryer in the manufacturing process of the paper products, resulting in locality of the paper. Peeling or breaking may occur. Furthermore, problems such as the dryer, press roll, blanket, etc. becoming dirty may occur frequently.

An example of the method of pulping waste paper to obtain recycled pulp for industrial paper is mainly the separation step of separating the waste paper pulp raw material to obtain a pulp suspension, and the subsequent step of removing foreign substances in the pulp suspension. It is composed of a separation step (first separation step and second separation step) for separation. In the separation step, most of the impurities contained in the pulp suspension are removed by dust removing equipment such as a screen and a cleaner, but some of the adhesive substances are not removed and remain in the waste paper pulp. This is because the specific gravity of the adhesive is relatively small, and the adhesive is not sufficiently removed from the pulp suspension by the separation by the cleaner that separates the foreign substances by the difference in specific gravity. In this way, when adhesive paper is mixed in the waste paper pulp raw material, the existing dust removal equipment cannot reliably remove the adhesive released from the adhesive paper mixed in the pulp suspension. The current situation.

(Gypsum-containing waste paper)
An embodiment of the present invention is characterized in that a gypsum-containing waste paper 10 and an adhesive paper 9 are mixed with the waste paper pulp raw material in a separation step of mechanically disintegrating the waste paper pulp raw material into a pulp suspension. .. Here, the gypsum-containing waste paper 10 refers to paper containing gypsum, and examples thereof include gypsum-containing waste paper such as paper attached to gypsum used as a building material and paper peeled from gypsum board. .. The gypsum derived from the gypsum-containing waste paper 10 is composed of needle-shaped or porous gypsum pieces, and the main component of the gypsum attached to the gypsum-containing waste paper 10 used in the present invention is calcium sulfate. This calcium sulfate has oil absorption and water absorption.

It is not clear how the sticky substance adheres to the gypsum, but it is probably as follows. The gypsum contained in the gypsum-containing waste paper 10 is a structure that is needle-shaped and has many pores. As an example, even if the gypsum board is crushed in the process of obtaining the gypsum-containing waste paper 10 from the gypsum board, the structure having the pores is maintained. In the process of disassembling the adhesive paper 9, finely divided adhesive substances are quickly attached to the structure, and water is absorbed to generate calcium sulfate particles to which the adhesive substances are attached. In addition, calcium ions dissolved in water inhibit the adhesiveness of acrylic resin adhesives, which are mainly used as adhesives. For example, fine sticky substances released in the turbid liquid adhere to gypsum before agglomeration, and the carboxyl groups present in the molecular chains of the acrylic resin constituting the sticky substances are contained in calcium carbonate and calcium sulfate in water. It is considered to have a mechanism in which adhesiveness is inhibited by reacting with calcium content and cross-linking.

The inventor has found that this makes it possible to easily remove the gypsum to which the sticky substance is attached as a solid content outside the system of the production flow.

The oil absorption amount of the calcium sulfate particles which are the main components of gypsum (the oil absorption amount specified in JIS K5101-13-1) is preferably 30 mL / 100 g or more, and more preferably 60 to 120 mL / 100 g. The oil absorption amount of this calcium sulfate means the oil absorption amount of the gypsum contained in the gypsum-containing waste paper 10.

When the oil absorption amount is within the above range, the degree of deterioration of the sticky substance removal efficiency and the adhesiveness is higher than the oil absorption amount outside the range. The reason for this is not clear, but the present inventors speculate as follows. First, the sticky substance adhering to the sticky paper is released from the sticky paper by a mechanical action such as a pulper. The free, finely divided, fine-grained sticky substance is dispersed in a pulp suspension, that is, a pulp turbid liquid. This fine-grained sticky substance adheres to the gypsum and is enlarged. Gypsum has the property of absorbing moisture and absorbs moisture to increase its own volume, so that it can be easily separated by a dust remover such as a cleaner. As a result, the gypsum to which this sticky substance is attached is easily discharged to the outside of the manufacturing flow system. Furthermore, the stickiness of the sticky substance is inhibited by the calcium ions dissolved from calcium sulfate. In addition, calcium sulfate has a non-lipophilic property, but it is presumed that if it has a structure having many pores, it adheres well to a lipophilic (hydrophobic) sticky substance.

When gypsum with an oil absorption of less than 30 mL / 100 g is used, the amount of sticky substance adhering to the gypsum is small, the granulation of the sticky substance is not promoted, and it becomes difficult to discharge the sticky substance out of the manufacturing flow system. .. In addition, the stickiness of the sticky substance is less likely to be inhibited.

The average particle size of the gypsum pieces adhering to the gypsum-containing waste paper used in the present embodiment is preferably adjusted in advance to a range of 0.5 to 5 mm, preferably to a range of 1 to 4 mm. Generally, pitch control talc used for the purpose of reducing the adhesiveness of a sticky substance includes inorganic particles smaller than this range, such as microcontrol (average particle system: 2.6 μm) manufactured by Imerys Specialties Japan. Talc) is used, but such talc cannot effectively achieve the object of the present invention. Even if an attempt is made to attach a sticky substance to a gypsum piece having an average particle size of less than 0.5 mm, it cannot be expected that the sticky substance will increase in size. If the gypsum piece has an average particle size of more than 5 mm, the effect of adhering the sticky substance is impaired due to its large size, and the stickiness may not be sufficiently inhibited.

In the present invention, the addition rate of gypsum is 0.1 to 5% by mass, preferably 0.3 to 5% by mass, and more preferably 0.5 to 2% by mass of the solid content of the adhesive paper. I hope it will be done. If the addition rate is less than 0.1% by mass, the desired effect of the present invention cannot be obtained. On the other hand, if the addition rate exceeds 5% by mass, the excessively added gypsum may induce stains in the pulp suspension (white water) and disturb the operations of the liquid removal process, the cleaning process, and the deinking process. is there. In addition, the degree of deinking is lowered, the quality of the used paper pulp to be manufactured is lowered, and the manufacturing cost is tight, which is not economical.

Of the gypsum to which paper is attached, for example, gypsum board is manufactured as described below. Diwater gypsum is baked and dehydrated (gypsum) is crystallized by containing water of crystallization for crystallization. Innumerable fine needles exist in this crystallized gypsum, and the crystals are intimately entwined with each other. By processing this gypsum into a board shape with a material other than gypsum and pasting the base paper on the board surface, the needle-shaped gypsum is entwined with the fibers of the base paper and adheres to form a gypsum board. The paper peeled off from this gypsum board is called "gypsum-containing waste paper of gypsum board". The gypsum content contained in a generally used gypsum board is highly useful when it is 75% or less, more preferably 5 to 70%, and further preferably 40 to 65%. Gypsum board is used as a building material and other materials for houses, etc., and has excellent stability, water resistance, heat resistance, heat insulation, soundproofing, ease of processing, etc., and has a wide range of uses.

(Raw material for used paper pulp)
The waste paper pulp raw material 11 includes the above-mentioned plaster-containing waste paper 10, as well as, for example, magazines, newspapers, medium-quality papers, high-quality papers, coated papers, finely coated papers, PPC papers (toner printing papers), cardboards, and the like. White paperboard, heat-sensitive recording paper equivalent to so-called waste paper contraindications, no-carbon paper, forms, high-quality colored paper, paper containers, stickers and labels may be included, and the surface of glossy printed matter, OP varnish, UV clear coat, etc. Processed printed matter may be included.

FIG. 1 shows an example of a flow (manufacturing flow) for producing waste paper pulp from the waste paper pulp raw material 11 including the gypsum-containing waste paper 10 and the adhesive paper 9. The outline of the process will be described with reference to FIG.

The embodiment shown in this manufacturing flow is as follows.
(1) Dissolution step by Pulper 12.
(2) Separation step. The separation step is further subdivided into a first separation step (coarse selection step) by the cleaner 13 and a second separation step (selection step) by the screen. However, the separation step may be only the first separation step (rough selection step) or only the second separation step (selection step).
(3) It has a liquid removal process.

(Crushing)
The gypsum-containing waste paper 10 is obtained by, for example, crushing gypsum to which paper is attached, prior to being put into the disintegration step. The crushed gypsum-containing waste paper 10 is put into the pulper (dissolution machine) 12 directly or together with the waste paper pulp raw material 11. When crushing gypsum to which paper is attached, fine gypsum or gypsum powder is generated. The fine gypsum or gypsum powder can be collected by, for example, a dust collector 8 provided at a place where the gypsum to which paper is attached is crushed. Then, when the collected gypsum is added to the disintegration step, a sticky substance adheres to the gypsum, and the gypsum to which the sticky substance adheres can be easily removed from the production flow system, which is preferable. Further, the collected gypsum component may be charged not only in the disintegration step but also in at least one of the first separation step and the second separation step. The dust collector 8 does not have to be provided.

In another embodiment, a duct is arranged between the place where the gypsum to which the paper is crushed and the pulper 12 used in the disintegration step, and fine gypsum or plaster powder is passed through the duct to pass the pulper. You may put it in 12.

<Dissociation process>
In the dissociation step, the pulper (dissociator) 12 is made of water, which is a waste paper pulp raw material 11 containing 0.1 to 10% by mass of gypsum-containing waste paper 10 and 0.1 to 10% by mass of adhesive paper in a dry solid content concentration. This is a process of adding water together to make mixed water and performing disintegration treatment. By the dissociation treatment, the used paper pulp raw material 11 is liquefied into pulp turbidity. In particular, it is preferable that the gypsum-containing waste paper 10 is 4 to 8% by mass. Further, it is preferable that the pressure-sensitive adhesive paper 9 is 1 to 4% by mass. By setting the ratio of the gypsum-containing waste paper to the adhesive waste paper in the above range, the gypsum content can be increased, the sticky foreign matter can be easily adsorbed, and the influence on the quality of the waste paper pulp can be reduced. If the amount of used paper 10 containing gypsum is less than 0.1% by mass, the disintegration efficiency is low, and if it exceeds 10% by mass, free gypsum may adhere to the used paper pulp raw material 11 or cause the pulper 12 to be worn. It becomes. Further, when the adhesive paper 9 is less than 0.1% by mass, the input amount of the adhesive paper 9 is too small, the production efficiency of the used paper pulp produced from the adhesive paper 9 is low, and the efficiency of the adhesive material described later is efficient. No granulation is done. If it exceeds 10% by mass, the concentration of the sticky substance released from the adhesive paper 9 becomes too high in the pulp turbid liquid (white water), which causes the adhesive substance to adhere to the waste paper pulp raw material or adhere to the pulper 12 and cause abrasion. It becomes. It is advisable to add the used paper pulp raw material 11 to the mixed water so that the amount is 4 to 20% by mass (dry solid content concentration).

The gypsum piece contained in the gypsum-containing waste paper 10 can be added in any of the steps of before the disintegration step, the disintegration step, the first separation step, the second separation step, and the liquid removal step. For example, the gypsum piece can be added before the raw material 11 of the used paper pulp is dissociated by the disintegration device in the disassembly step. Further, gypsum pieces may be added to the pulp suspension after the dissociation treatment of the used paper pulp raw material 11 including the adhesive paper 9.

The inventors have found that the waste paper pulp obtained from the gypsum-containing waste paper 10 contains a large amount of calcium, and this calcium content may cause scale and equipment wear in the papermaking process and hinder the effect of paper-making chemicals. There is. Therefore, in the present embodiment, it is preferable to add an ion sequestering agent in at least one step of the disintegration step, the first separation step, the second separation step, and the liquid removal step to reduce the calcium ion concentration. However, if the calcium content (gypsum piece or calcium ion) is low, it becomes difficult for the finely divided sticky substance to adhere to the gypsum piece, so it is not necessary to add an ion blocking agent.

(water temperature)
The water temperature during the disintegration treatment is preferably less than 50 ° C. Further, it is more preferable that the temperature is lower than 45 ° C. Calcium sulfate is predominantly contained in the gypsum component. Here calcium sulfate is a concept including calcium anhydrate sulfate, calcium sulfate hydrate _{(e.g., CaSO 4 · 2H 2 O,} CaSO 4 · 1 / 2H 2 O , etc.). When the water temperature during the disintegration treatment is 50 ° C. or higher, the solubility of calcium sulfate in water becomes relatively small. The gypsum piece becomes relatively difficult to dissolve in water, and as a result, the separation performance between the gypsum piece and the gypsum-containing waste paper 10 is deteriorated.

(solubility)
FIG. 2 is a graph showing the results of measuring the solubility 31 of calcium sulfate anhydrate in 100 g of water at normal temperature and pressure. In the figure, the horizontal axis shows the temperature (° C) and the vertical axis shows the solubility (%).

(Ion blockade)
The ion sequestering agent can be added in the disintegration step. By adding an ion sequestering agent, the concentration of calcium ions that are dissociated from the gypsum-containing waste paper 10 and dissolved in water can be reduced. When calcium ions are contained in the disaggregated pulp turbid liquid, the calcium ions are scaled in a later process, and the scale adheres to the waste paper pulp manufacturing equipment and waste paper pulp, resulting in wear of the manufacturing equipment and deterioration of the quality of the manufactured products. Will cause. Here, the scale means, for example, one in which calcium carbonate, calcium sulfate, etc. contained in the water of the treatment step is solidified and precipitated.

The ion sequestering agent may be added so that the concentration of the ion sequestering agent contained in the mixed water is 4.0 to 20.0 kg / pulp 100 kg. If it is lower than 4.0 kg / 1000 kg of pulp, the effect of precipitating calcium content is weak. On the other hand, if the weight is higher than 20.0 kg / 1000 kg of pulp, by-products such as complexes may be generated, or the ion blocker itself may solidify and adhere to the manufacturing equipment, which may cause problems in the production of used paper pulp. In some cases.

When the ion blocker is added, the calcium ions ionized by the dissolution of the gypsum piece are solidified, and the precipitation of calcium content is promoted. In addition, the removal of gypsum, which is performed in a later step, can be effectively performed. Further, it is possible to reduce the amount of paper-making chemicals such as paper strength enhancer and sizing agent used in the subsequent process. As a result, the basic unit of the manufactured product can be kept low, which is preferable.

An example of the chemical reaction between calcium ions dissolved in water and an ion blocker is as follows. Gypsum is the major component of gypsum-containing waste paper _{10 (CaSO 4 · 2H 2 O} ) calcium ion (Ca ²⁺⁾ is produced when dissolved in water (equation (1)). When an ion blocker (for example, H ₃ PO ₄ ) is added to water containing this calcium ion (Ca ²⁺ ), poorly soluble calcium phosphate is produced in water (formula (2)). In the formula (2), calcium dihydrogen phosphate is given as an example of the calcium phosphate produced, but in addition, calcium dihydrogen phosphate hydrate, calcium monohydrogen phosphate, calcium monohydrogen phosphate hydrate Etc., a product containing phosphoric acid and calcium ions is produced.
[Chemical 1]
_{CaSO 4 · 2H 2 O → Ca} 2+ + SO 4 2+ 2H 2 O ··· (1)
[Chemical 2]
Ca ²⁺ + H ₃ PO ₄ → Ca (H ₂ PO ₄ ) ₂ ↓ + 2H ⁺・ ・ ・ Equation (2)

A tank for temporarily storing the pulp turbid liquid after the disintegration step may be provided, and an ion sequestering agent may be added to the pulp turbid liquid stored in this tank. In this case, the ion sequestering agent may or may not be added in the disintegration step.

The ion blocking agent used in the present embodiment is not particularly limited as long as it chemically reacts with calcium ions in water to form a water-insoluble precipitate. Examples include phosphoric acid, phosphates, oxalic acid, oxalates and the like. By adding these ion blockers, the dissolution of calcium sulfate contained in gypsum in water can be suppressed. Then, the gypsum component can be easily removed from the system in the manufacturing process after the addition of the ion sequestering agent. Examples of phosphoric acid and phosphates include condensed phosphoric acid such as orthophosphoric acid and alkali metal first, second and third phosphates, pyrophosphoric acid and tripolyphosphoric acid, and condensation of pyrophosphate alkali metal salt and tripolyphosphoric acid. Examples thereof include an alkali metal salt of phosphoric acid and a primary metal phosphate salt used as a binder, but the present invention is not limited thereto.

(Dissociation time)
In the pulper 12 used in the disassembly step, the waste paper pulp raw material 11 is sheared by the disassembly blade provided in the pulper 12. The time for performing the disintegration process (dissolution time) in this disintegration step is 15 to 30 minutes, more preferably 15 to 25 minutes. If it exceeds 30 minutes, the debris of the gypsum is promoted by stirring and disintegrating in the pulper 12, and the gypsum residue is made finer. The gypsum has a specific gravity of about 2.2 g / cm ³ , and can be removed by a cleaner in the first separation step and the second separation step of the next step. However, if the gypsum is further miniaturized, it can be removed by the cleaner. It may lead to a decrease in efficiency. Further, if the gypsum content contained in the gypsum-containing waste paper 10 is excessively miniaturized, the gypsum content passes through the screen in the second separation step and is not recovered. In addition, the gypsum content is not effectively removed because the sticky substance is hard to adhere to the gypsum content that has been made excessively fine and the granulation of the sticky substance is not promoted. Then, the produced waste paper pulp contains gypsum and calcium, which may not be of good quality. If the disintegration time is shorter than 15 minutes, the waste paper pulp raw material 11 other than the gypsum-containing waste paper 10 may not be sufficiently dissociated.

(PH)
The pH of the mixed water during the disintegration treatment performed in the disintegration step is preferably 6 to 10. Further, the pH is preferably 6 to 7, and more preferably 6 to 6.8. At pH in this range, the solubility of gypsum hardly fluctuates. If the pH is more acidic than 6, it may be necessary to add a large amount of chemicals such as a pH adjuster. When a large amount of this chemical is added, calcium carbonate contained in the manufacturing process of used paper pulp is dissolved, and as a result, calcium sulfate and the like are generated, which causes scale. On the other hand, if the pH is on the alkaline side of more than 10, alkaline-derived scale may be generated in waste paper pulp manufacturing equipment, for example, piping. The cause of this scale is not clear, but it is probably due to the gypsum dissolved in the alkaline solution being precipitated due to subsequent changes in pH.

(Pulper)
In the disintegration step, the waste paper pulp raw material 11 containing the adhesive paper 9 and the gypsum-containing waste paper 10 is put into the pulper 12 and dissociated. The structure of the pulper 12 is not limited. For example, the waste paper pulp raw material 11 and water are put into the tab provided in the pulper 12 to prepare mixed water, and the mixed water is agitated and dissociated by the rotation of the rotor provided at the lower part of the tab or the side surface. To. The pulper 12 can be used without particular limitation, and may be any of low-concentration pulper, medium-concentration pulper, and high-concentration pulper. Approximately low-concentration pulper dissociates waste paper pulp raw material at 3 to 5% by mass (dry solid content concentration), medium-concentration pulper dissociates at 5 to 13% by mass (dry solid content concentration), and high-concentration pulper dissociates from 13 to 18%. It can be dissociated by mass% (dry solid content concentration). It is preferable to add the used paper pulp raw material 11 to the pulper 12 so as to have a dry solid content concentration of 3 to 18% by mass with respect to the mixed water, and an appropriate pulper 12 is used according to the dry solid content concentration of the used paper pulp raw material 11. be able to. However, it is not limited to this range.

The high and low concentrations of the dry solid content of the used paper pulp raw material 11 affect the shearing force of the used paper pulp raw material 11 stirred by the pulper 12. When the dry solid content concentration is lower than 3% by mass, the concentration of calcium ions dissolved from the gypsum-containing waste paper 10 is relatively low, and the advantage of adding an ion blocker is poor. Further, the waste paper pulp raw material 11 receives a mechanical shearing force due to the rotation of the release blade and the stirring blade provided in the pulper 12. As a result, the gypsum component adhering to the gypsum-containing waste paper 10 is subdivided, and it becomes difficult to separate the gypsum due to the subsequent steps, for example, the difference in gravity due to the cleaner 13. On the other hand, if the concentration is higher than 18% by mass, it becomes necessary to add a large amount of ion blocking agent. As described above, the addition of a large amount of the ion blocker is not preferable. Further, the frictional force between the fibers of the waste paper pulp raw materials 11 acts predominantly in the flow of the mixed water, and the gypsum content is dispersed and fragmented, which causes the cleaner 13 to be worn.

Examples of the pulper 12 for dissociating the waste paper pulp raw material containing the gypsum-containing waste paper 10 include a tab-type pulper and a drum-type pulper. Further, the operation of the pulper may be a batch type or a continuous type.

<Separation process>
The separation step is a separation step of separating and removing the gypsum component from the pulp turbid solution to obtain a residue. The separation step may be subdivided into, for example, a first separation step (coarse selection step) by the cleaner 13 and a second separation step (selection step) by the screen. In this case, in the first separation step (coarse selection step), the heavy substance in the pulp turbid liquid is separated and removed due to the difference in specific gravity, and the first residue (coarse selection step) is obtained. In the second separation step (selection step), the first residue (coarse selection) is separated and removed based on the size, and the second residue (selection) is obtained. Further, the separation step may be only the first separation step (coarse selection step) or only the second separation step (selection step).

<First separation step>
The raw material 11 of the used paper pulp is dissociated in the dissociation step and sent as a pulp turbid liquid to the first separation step which is the next step. However, the pulp turbid liquid may be sent to the second separation step without going through the first separation step.

The first separation step is a step of separating heavy foreign matter and other residuals by a difference in specific gravity using a rough selection facility (cleaner 13). In addition to this rough selection equipment, when a screen equipment for removing dust, a screen equipment for removing foreign matter having a relatively small difference in specific gravity, a tank 14 for temporarily storing the first residual residue, etc., which will be described later, are provided. The equipment and the tank 14 may be included in the first separation step. The first separation step may be a step of only the first rough selection process, or may be a step of performing a second rough selection process on the first residual after the first rough selection process. The pulp turbid liquid is charged into the cleaner 13, and a swirling flow is generated in the cleaner 13 in a state where water is appropriately injected. Heavy foreign matter contained in the pulp turbid liquid is separated by centrifugal force in a swirling flow, removed (discharged), and the first residue is recovered. As the cleaner 13, for example, a high-concentration cleaner used for a dry solid content concentration of 3 to 5% by mass or a medium-concentration cleaner used for a dry solid content concentration of 1 to 3% by mass can be used. One or a plurality of cleaners 13 may be provided, and when a plurality of cleaners 13 are provided, the cleaners 13 may be arranged in series or in parallel to charge the pulp turbid liquid into each of the cleaners 13 in series or in parallel. In the treatment with the cleaner 13, it is preferable to appropriately inject water into the pulp turbid liquid to remove the gypsum while suppressing further miniaturization of the gypsum. Here, the heavy foreign matter may include gypsum, sand and the like in addition to metals (for example, iron, copper, aluminum and other metals).

(Cleaner)
As the cleaner 13, one or a plurality of high-concentration cleaners may be installed, or one or a plurality of medium-concentration cleaners may be installed. Further, a high-concentration cleaner and a medium-concentration cleaner may be installed in combination. As an example, the first rough selection treatment may be performed with a high concentration cleaner, and the first residual amount thereof may be subjected to the second rough selection treatment with a medium concentration cleaner. Further, the first rough selection treatment may be performed with a medium concentration cleaner, and the first residual amount thereof may be subjected to a second rough selection treatment with a high concentration cleaner. A rough selection process in which a high-concentration cleaner and a medium-concentration cleaner are combined has the following advantages and is preferable. The residue from which the gypsum component has been removed by the first rough selection process may contain finely divided gypsum content. By performing the second rough selection treatment on the first residue, the gypsum component is further removed, and the quality of the used paper pulp can be improved.

The cleaner 13 puts the contents (for example, pulp turbid liquid) into the cleaner 13 to generate a swirling flow, applies centrifugal force to the pulp turbid liquid, and separates the pulp turbid liquid by a specific gravity difference to obtain a first residue. .. Explaining with reference to FIGS. 3 to 5, the cleaner 13 is a conical device that narrows toward the lower part, and the upper part of the cleaner 13 is substantially circular in a plan view. The upper part of the main body of the cleaner 13 is provided with a charging portion 13a for charging the pulp turbid liquid through the wall surface of the cleaner 13. The pulp turbid liquid is charged into the cleaner 13 from the outside of the cleaner 13 through the charging unit 13a. Then, it is preferable to determine the charging direction 13c so that the pulp turbid liquid charged from the charging unit 13a flows along the swirling flow immediately after charging. The charging portion 13a can be tubular or tubular. The angle θ formed by the charging direction 13c at which the pulp turbid liquid flows into the cleaner 13 through the charging portion 13a and the axial center 13b of the cleaner 13 body may be an acute angle. The same angle θ means that the same loading direction 13c and the axial center 13b of the cleaner 13 body have a twisted positional relationship, but the loading direction 13c is translated in a positional relationship where the axial center 13b and the charging direction 13c intersect. The angle when it hits. In other words, it refers to the angle θ formed by the axis 13b and the loading direction 13c in a cross section (that is, the paper surface shown in FIG. 4) cut through the axis 13b and parallel to the loading direction 13c. The heavy foreign matter 33 is discharged from the discharge unit 13f provided in the lower part of the cleaner 13, and the first residual portion 32 is collected from the collection part 13d provided in the center of the upper end. The heavy foreign matter 33 of the pulp turbid liquid charged from the charging unit 13a spirally swirls along the swirling flow and falls by gravity. By setting the same angle θ to an acute angle, the pulp turbid liquid swirls along the swirling flow immediately after being charged into the cleaner 13, and a large centrifugal force is obtained. As a result, the contents are separated with high resolution due to the difference in specific density. The charging direction 13c of the pulp turbid liquid and the direction of the swirling flow are substantially the same at the tip of the charging portion 13a inside the cleaner 13. Here, the same angle θ is preferably 10 ° to 80 °, more preferably 20 ° to 70 °, and preferably 30 ° to 60 °. When the angle θ is less than 10 °, it becomes difficult for the pulp turbid liquid to obtain centrifugal force, and when the angle exceeds 80 °, it becomes difficult to charge the pulp turbid liquid.

The specific gravity of gypsum is 2.3 g / cm ³ , which is smaller than the specific density of other foreign substances contained in the waste paper pulp raw material 11, for example, iron, copper, and aluminum, and may not be sufficiently separated by the cleaner 13. .. When the pulp turbid liquid is charged at the above-mentioned angle θ, the pulp turbid liquid obtains a large centrifugal force. As a result, the inventor knows that a large centrifugal force can be obtained even for gypsum having a relatively small difference in specific gravity from that of used paper pulp, and most of the gypsum can be discharged as heavy foreign matter 33. ..

The pulp turbid liquid (dry solid content concentration) in the rough selection treatment with the cleaner 13 is preferably 2.0 to 5.5% by mass, more preferably 2.5 to 5.0% by mass. If it is less than 2.0% by mass, the productivity will be lowered, and if it is more than 5.5% by mass, the calcium ion concentration will be high, which will adversely affect the subsequent process or the separation due to the difference in specific gravity will not be suitable. It causes to. Prior to the first separation step, a concentration adjusting step of diluting the pulp turbid solution or dehydrating and concentrating the pulp turbid solution may be provided in order to carry out the rough selection treatment in an amount of 2.0 to 5.5% by mass.

For example, when the pulp turbid liquid contains gypsum as well as sand such as iron, copper, and aluminum, two cleaners 13 are arranged in series, and the first cleaner 13 removes heavy foreign substances and leaves a residue. It is also possible to take a method of removing the plaster by flowing the minute into the second cleaner 13. Separation performance of lightweight and heavy foreign matter by appropriately adjusting conditions such as pulp turbidity input pressure of cleaner 13, outlet pressure of lightweight material, outlet pressure of heavy foreign matter, water pressure of injected water, concentration of pulp turbid liquid 13. Changes. By adjusting these conditions, the gypsum content of a desired size can be separated from the pulp turbid liquid. The specific gravity (g / cm ³ ) is 7.8 for iron, 8.5 for copper, 2.7 for aluminum, and 2.3 for gypsum.

(processing time)
As long as sufficient rough selection processing is performed, the processing time of the cleaner 13 is not particularly limited, and can be appropriately adjusted in consideration of, for example, workability. As an example, when a plurality of cleaners 13 are installed to process pulp turbid liquid in series, the processing time of the first rough selection process is adjusted to be relatively short and the specific density is larger than that of used paper pulp ( The one with a relatively large difference in specific gravity is removed mainly, and the processing time of the second rough selection process is adjusted to be relatively long, and the one with a slightly larger specific density than the used paper pulp (relative to the difference in specific density) is removed. It can be adjusted to remove the small ones in the center.

(Ion blockade)
In the first separation step, an ion sequestering agent can be added to perform a rough selection treatment. Calcium ions are contained in the pulp turbid liquid. The reaction between these calcium ions and the ion blocker produces poorly water-soluble calcium phosphate and calcium oxalate, which are precipitated as a solid. Since the calcium content is solidified, the calcium content can be easily discharged to the outside of the waste paper pulp manufacturing process. If calcium ions are present in the papermaking process, they react with chemicals such as sizing agents and paper strength agents, causing a decrease in the chemical effect. It also causes the generation of pitch-like substances in white water.

(tank)
A tank 14 can be provided downstream of the cleaner 13 to make the quality of the residue processed by the cleaner 13 uniform. Also in this tank 14, it is advisable to add an ion blocking agent to precipitate the calcium content.

(temperature)
The treatment of the object to be treated (pulp turbid liquid, white water, water used for dilution, liquid used for circulation, etc.) in the first separation step can be performed at room temperature. Further, treatment at 50 ° C. or higher, more preferably 55 ° C. or higher is preferable because the solubility 31 of the calcium sulfate anhydrate is relatively small. From the viewpoint of work safety and wear prevention of various facilities, the upper limit of the temperature of the treatment should be 80 ° C. By treating the pulp turbid liquid at 50 ° C. or higher in this way, a part of calcium ions and a part of sulfate ions dissolved in the liquid content (for example, water) of the object to be treated containing the pulp turbid liquid are combined. It is precipitated as calcium sulfate. The precipitated calcium sulfate is removed from the cleaner 13, the screen, and the next step. In addition, since the calcium ion concentration of the liquid to be treated decreases, the generation of scale is suppressed. It should be noted that the finely divided sticky substance in the object to be treated adheres to the precipitated calcium sulfate to increase the grain size, and the volume of the precipitate increases, so that the precipitate can be easily removed in the first separation step. become.

However, the solubility of calcium sulfate tends to decrease even at low temperatures (see FIG. 2). For example, treatment at 25 ° C. or lower, more preferably 20 ° C. or lower is also preferable for the same reason. However, the lower limit of the treatment temperature may be set to 10 ° C. in consideration of the active temperature of the ion blocking agent, the coagulant, the coagulant, the adhesive, etc., and the stable operation of the equipment.

(Dust removal process)
A dust removal step may be inserted prior to charging the residue after the first separation step into the second separation step. When foreign matter other than waste paper pulp is mixed in the same residue, this foreign matter can be removed by the dust removal step. Various known screen equipment can be used in the dust removal step.

As described above, metals, sand, gypsum, etc. can be removed by the cleaner 13 using the difference in specific density from the used paper pulp, but foreign substances having a relatively small difference in specific gravity from the used paper pulp are removed by the cleaner 13. Is difficult. Various known screen equipment may be provided to remove such foreign matter. It is preferable that this screen equipment is provided on the downstream side of the cleaner 13. When this screen equipment is provided, water can be appropriately added to the object to be passed through the screen to dilute it.

<Second separation step>
The second separation step is a step of obtaining a second residue by separating and removing large foreign substances contained in the first residue 32 based on the size. Specifically, the first residue 32 from which heavy foreign matter has been removed by the first separation step is put into the second separation step which is the next step. In the second separation step, a screen facility is provided, and the same residue is passed through the screen facility to separate the large foreign matter that did not pass and the second residue (passed object) that passed. The same large foreign matter is removed outside the manufacturing flow system. The large foreign substances to be removed are mainly undissolved raw materials such as coarse undissolved waste paper and lightweight foreign substances that could not be completely removed by the cleaner 13. Further, the finely divided sticky substance in the object to be treated adheres to the precipitated calcium sulfate to increase the grain size, and the volume of the precipitate increases. Therefore, this precipitate is also easily removed in the second separation step. Will be done.

(Screen equipment)
As an example of screen equipment, a hole screen having a large number of through-hole round hole shapes can be presented. The diameter of the round hole is preferably 1.2 to 2 mm, more preferably 1.7 to 2 mm. The material to be passed through the screen equipment (the first residue 32 described above) is preferably a dry solid content concentration of 3% by mass or less. If the concentration is higher than this, the screen equipment may be blocked. The second residue (passing material) that has passed through the screen equipment is guided to the next step, the deliquescent step. Large foreign substances that have not been passed through the screen equipment are removed from the manufacturing flow system.

In order to efficiently process the above-mentioned residue, a plurality of screen equipment can be provided and processed in parallel.

In addition, two types or three or more types of screen equipment having different diameters are provided and can be arranged in series for processing. When two types of screen equipment are provided, for example, a passing object of the first screen equipment may be passed through yet another screen equipment. As an example of another screen equipment, a slit screen having a slit width of 0.25 to 0.4 mm and further of 0.25 to 0.3 mm can be presented. This screen equipment is preferable because it can remove plaster, undissolved components, and foreign substances to which adhesive substances are attached, which are larger than the slit width.

Further, as a modification of the screen equipment, the arrangement shown in FIG. 1 can be presented. The above-mentioned first residue 32 is processed in parallel by two screen equipments (15, 16), and the passing material of the screens (15, 16) is sent to the next process. In addition, large foreign substances that have not been passed through the two screen facilities (15, 16) are collected in the tank 17. This foreign matter is urged to dissociate in the tank 17 and then sent to the screen equipment 18. The passing material (second residue) of the screen equipment 18 is sent to the next process, and the large foreign matter that has not passed through the screen equipment 18 is collected in, for example, the tank 19 and removed from the production flow system.

(temperature)
The treatment of the object to be treated (pulp turbid liquid, white water, water used for dilution, water used for circulation, etc.) in the second separation step can be performed at room temperature. Further, when the treatment is carried out at 50 ° C. or higher, more preferably 55 ° C. or higher, the solubility 31 of the calcium sulfate anhydrate is relatively small, and the calcium content is precipitated, which is preferable. From the viewpoint of work safety and wear prevention of various facilities, the upper limit of the temperature of the treatment should be 80 ° C.

However, the solubility of calcium sulfate tends to decrease even at low temperatures. For example, treatment at 25 ° C. or lower, more preferably 20 ° C. or lower is also preferable for the same reason. However, the lower limit of the treatment temperature may be set to 10 ° C. in consideration of the active temperature of the ion blocking agent, the coagulant, the coagulant and the like, and the stable operation of the equipment.

<Liquid removal process>
The selected product (second residue) that has passed through the screen equipment in the second separation step is introduced into the liquid removal step, which is the next step. The liquid removal step is a step of reducing the amount of liquid contained in the selected product. The liquid removal step includes a dehydration treatment by the liquid removal equipment 20 and a dehydration treatment by the pre-dewatering device when a pre-dewatering device is provided. In the liquid removal step, the selected product is liquid-removed regardless of the dry solid content concentration. As an example, it is preferable that about 0.1 to 2% by mass of the selected product is deflated to about 5 to 25% by mass. By removing the liquid within this range, calcium ions and fine gypsum in the liquid contained in the selected product can be reliably removed.

(Draining equipment)
An example of the deliquescent equipment 20 used in the deliquescent process is a filtration / dehydrator using a pulp mat such as a disc extract or a disc thickener, a screen plate (extraction plate), an SP filter, a filter such as trommel, and a natural product using a dehydration element. A dehydrator can be presented.

(Dissolution time)
The time for deliquescing the selected product (second residue) with the deliquescent equipment 20 and the preliminary deliquescing device described later is not particularly limited. It may be appropriately adjusted according to the physical properties of the used paper pulp raw material 11 and the dry solid content concentration of the selected product (second residue).

(Preliminary liquid removal device)
Prior to introducing the selected product (second residue) into the above-mentioned liquid removal equipment 20, a preliminary liquid removal device may be provided. In the preliminary liquid removal device, the selected product (second residue) having a dry solid content concentration of about 1% can be liquidated to a dry solid content concentration of 3% or more. By introducing a selected product (second residue) from which a predetermined amount of calcium ions and fine gypsum have been removed by a preliminary liquid removal device into the liquid removal facility 20 and treating it, the efficiency of removing more calcium and fine gypsum can be improved. improves.

(temperature)
The treatment of the selected product (second residue) performed in the liquid removal step can be performed at room temperature. Further, when the treatment is carried out at 50 ° C. or higher, more preferably 55 ° C. or higher, the solubility 31 of the calcium sulfate anhydrate is relatively small and the calcium content is precipitated, which is preferable. From the viewpoint of work safety and wear prevention of various facilities, the upper limit of the temperature of the treatment should be 80 ° C.

(Coagulant, etc.)
When introducing the selected product into the liquid removal step, a coagulant or a coagulant can be added. The addition is performed, for example, immediately before introducing the selected product (second residue) into the liquid removal facility 20, or / and when a preliminary liquid removal device is provided, the selected product (second residue) is introduced into the preliminary liquid removal device. It can be done just before.

The addition rate of the coagulant and the coagulant depends on the structure of the equipment and the like, but it is preferable that the dry solid content concentration is 0.005 to 0.05% by mass with respect to the selected product (second residue), and 0.01 to 0. It is more preferable to set it to 04% by mass. When the addition rate is lower than 0.005% by mass, the incorporation of inorganic substances into the selected product (fiber aggregate) is insufficient, and the aggregation effect and the coagulation effect are small. If the addition rate is higher than 0.05% by mass, the pulp fibers of the selected product are extremely agglomerated, causing deterioration of the texture, and the cost of the coagulant / coagulant is also high, which is not practical.

As the component of the flocculant used in the present embodiment, either a polymer flocculant or an inorganic flocculant that has been conventionally used as a yield improver can be used. Examples of the polymer flocculant include organic polymer-based flocculants such as polyacrylamide (PAM), polyvinylamine (PVAm), polyamine (PAm), and polyethylene oxide (PEO). In particular, it is preferable to use at least one of PAM and PAM. Examples of the coagulant include polyacrylamide (PAM), polyvinylamine (PVAm), polydiallyldimethylammonium chloride (polydadomac, PDADMAC), polyamine (PAm), polyethyleneimine (PEI), polyethylene oxide (PEO), methacrylic acid and the like. Examples thereof include organic polymer-based coagulants and inorganic coagulants such as sulfuric acid bands and polyaluminum chloride.

(Washing process)
Processed product (for example, pulp turbid liquid, first residue 32 (recovered from cleaner 13), carefully selected) that has undergone at least one or more steps of at least one of the above-mentioned disintegration step, first separation step, and second separation step. It is also possible to insert a cleaning step for appropriately cleaning an object (second residue) or the like).

(Circulating fluid)
Liquids are included in the products removed in the disintegration step, the first separation step, the second separation step, and the liquid removal step. By sending this liquid component again as the circulating liquid 41 to at least one or more of the disintegration step, the first separation step, and the second separation step, the liquid is discharged from the waste paper pulp production flow to the outside of the system. The amount can be reduced. When the circulating liquid 41 is sent again, it is preferable to remove the calcium content contained in the liquid content in the removed product before flowing it in. As an example of a method for removing calcium content, a method of adding an ion blocker and precipitating it can be mentioned. Further, since the liquid component contains an ion blocking agent, the total amount of the ion blocking agent added can be reduced in a series of manufacturing steps by using the liquid component as the circulating liquid 41, which is economical.

(Other equipment)
The deliquescent material deliquesed in the deliquescent step, that is, used paper pulp, is sent to the production of paper. Depending on the progress of paper production, tanks 21, 22, and 23 for temporarily storing the deliquescent material can be provided in order on the downstream side of the deliquenation process. The tank 21 is a tank for temporarily storing the deflated material that has undergone the liquefied step. The tank 22 is a tank for temporarily storing the used paper pulp, which is the liquidated product, in order to send the used paper pulp to the papermaking process at predetermined intervals. The tank 23 is a tank for storing raw materials for the papermaking process. Not only used paper pulp but also pulp containing various raw materials is mixed in the raw material. The seed box 24 is a device for stably supplying a raw material for papermaking to the papermaking process.

(Physical properties of used paper pulp)
The used paper pulp containing plaster obtained through the production flow of the present embodiment can be used as a paper raw material by satisfying the physical property values described later, and is preferably used for paperboard, cardboard base paper, core base paper and the like. It can be used as a raw material for thick paper and paper that requires strength.

The Canadian standard freeness (hereinafter, also simply referred to as “freeness”) is preferably 360 mL to 580 mL, and more preferably 450 mL to 520 mL or less. Within this range, when used as a raw material for thick paper such as paperboard, corrugated cardboard, core base paper, etc., dehydration is good and papermaking is easy, and the strength and elongation of the obtained paper are optimized.

The specific burst strength is preferably 14 (N · cm ² ) × 100 / (g / m ² ) to 30 (N · cm ² ) × 100 / (g / m ² ), and is preferably 18 (N · cm ² ) × 100. / (G / m ² ) to 22 (N · cm ² ) × 100 / (g / m ² ) is more preferable. Within this range, it is suitable as a raw material for thick paper such as paperboard, corrugated cardboard, and core base paper, which requires strength.

Specific ring strength is preferably ^{132N · m 2 / g · 100~206N} · m 2 / g · 100, more preferably ^{160N · m 2 / g · 100~190N} · m 2 / g · 100. Within this range, it is suitable as a raw material for thick paper such as paperboard, corrugated cardboard, and core base paper, which requires strength.

The ash content is preferably 10.0% to 25.0% or less, more preferably 12.0% to 15.0%. Within this range, the obtained paper can reduce the decrease in size due to the influence of the ash content (filler), and can further impart rigidity. It is presumed that this is because the gypsum in the ash has a function as a filler. If it is less than 10.0%, the effect as a filler derived from gypsum cannot be obtained. If it exceeds 25.0%, the content ratio of inorganic substances such as inorganic salts is high and the strength of the pulp is not sufficient.

The 6-cut residue is preferably 0.1% to 6.0%, more preferably 0.6% to 2.0%. Within this range, the strength and elongation of the obtained paper are optimized. Below 0.1%, gypsum does not fully function as a filler. If it exceeds 6.0%, the pulp fibers may be bound, and the strength of the pulp becomes insufficient.

(Paper manufacturing)
Paper is produced using the deliquescent material (waste paper pulp) obtained through the production flow of the present embodiment. The papermaking process in the production of paper can employ a known method and is not particularly limited. In the present invention, waste paper pulp is produced using the waste paper pulp raw material 11 containing the adhesive paper 9 and the gypsum-containing waste paper 10 which have been difficult so far. According to the present invention, the sticky substance adhering to the adhesive paper 9 and the gypsum component adhering to the gypsum-containing waste paper 10 are surely removed. Therefore, in the case of papermaking or processing, when the paper is stored for a long period of time, the generation of spots, the adhesion of foreign substances, and the adhesion by adhesives are effectively suppressed. From this, the present invention can effectively utilize the adhesive paper 9 and the gypsum-containing waste paper 10 which have been disposed of in the past at the same time, and is extremely useful from the viewpoint of resource reuse.

The raw material used in the papermaking process can be the used paper pulp obtained by the present embodiment. However, a raw material obtained by blending not only the used paper pulp but also other pulp with the used paper pulp obtained by the present embodiment in an arbitrary ratio can be used in the papermaking process. Here, as the other pulp, the following can be used.

For example, deinked pulp (DIP), coniferous or broadleaf kraft pulp (NKP or LKP), mechanical pulp using coniferous or broadleaf, such as crushed wood pulp (GP), refiner crushed wood pulp (RGP), thermomechanical pulp (TMP). , Chemithermo Mechanical Pulp (CTMP), Chemigrand Pulp (CGP), Semi-Chemical Pulp (SCP), etc., used paper pulp from which cardboard has been separated, coated paper, coated base paper, and other waste paper including paper. Coat broke and a mixture of two or more of these pulps may be used in combination to make paper.

Further, in the present invention, a chemical or a filler may be added when the paper is made. Chemicals to be added include rosin emulsions, neutral rosins, alkyl keten dimers, alkenyl anhydride succinic acid, sizing agents such as styrene / acrylic copolymers, cationic, amphoteric, and anionic polyacrylamides, polyvinylamines, and polys. Resins containing acrylic acid, dry paper strength enhancers such as guar gum, cationic, amphoteric, and anionic modified starches, wettable strength enhancers such as polyamideamine epichlorohydrin and carboxymethyl cellulose, drainage improvers, Examples thereof include colorants, dyes, fluorescent dyes, coagulants, bulking agents, and retention agents. Further, the filler may be particles generally called inorganic filler and organic filler, and is not particularly limited. Specifically, as inorganic fillers, calcium carbonate (light calcium carbonate, heavy calcium carbonate), magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay (kaolin, calcined kaolin). , Delamicaolin), talc, zinc oxide, zinc stearate, titanium dioxide, silica (white carbon, silica / calcium carbonate complex, silica / titanium dioxide complex), white clay, bentonite produced from sodium silicate and mineral acid. , Calcium carbonate, calcium sulfate, and a reclaimed filler that regenerates and utilizes the ash obtained from the deinking step are preferably used.

The present invention will be described below with reference to specific examples, but the present invention is not limited to the following examples. Waste paper pulp was produced according to the production flow of FIG.
(1) Dissolution step Adhesive paper 9 and gypsum-containing waste paper 10 and waste paper pulp raw material 11 including corrugated cardboard waste paper and an ion sequestering agent are added to a tab-type low-concentration pulper, and water is added thereto to a treatment concentration of 5.0% by mass. The disintegration process was performed under the conditions shown in Table 1.
(2) First Separation Step Water was added to the pulp turbid liquid treated with the tab-type low-concentration pulper of (1) above, and the pulp was treated with a high-concentration cleaner (treatment concentration: 4.0% by mass).
(3) Second Separation Step The residue after the first separation step of (2) above is passed through a hole screen (diameter: 2.0 mm, round hole shape) to remove undissolved raw materials and lightweight foreign substances that have not passed through. , The passing material was passed through a slit screen (slit width: 0.25 mm) to remove foreign substances such as fine gypsum that did not pass through, and the passing material (selected product) was guided to the liquid removal step.
(4) Deliquescent Step The selected product obtained in (3) above was deliquesed and concentrated in a deliquescent concentration facility until the deliquescent concentration (dry solid content concentration) shown in Table 2 was reached to obtain used paper pulp.

結果から、本発明の実施形態に係る製造方法にて得られた古紙パルプは、灰分が比較的少なく、かつ良好な品質を具備したものであることがわかる。 Each characteristic (physical property) of the obtained used paper pulp was measured by the following method.
<Quality evaluation>
(A) Ash content Measured according to the method described in JIS P 8251 “Paper, paperboard and pulp-ash content test method-525 ° C. combustion method”.
(B) 6-cut residue Described in "Temporary Industry Standards and Operation of Recyclable Stickers (Fully Dissociable Adhesive Paper)" issued by the Printing Adhesive Paper Manufacturers Association dated October 17, 2006. 1) Measured according to the evaluation test method.
(C) Canadian Standard Freeness (CSF)
The measurement was performed using a Canadian standard free nester (model number: Canadian standard drainage meter, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with the method described in JIS P 8251 “Pulp freshness test method”.
(D) Specific burst strength A pulp sheet prepared in accordance with the method described in JIS P 8222 "Adjustment method for test hand-made paper" is used for JIS P 8223 "Test hand-made paper-testing of physical properties". The measurement was performed in accordance with the method described in JIS P 8112 “Rupture strength test method for paper and paperboard by Mullen low pressure rupture tester” specified in “Method”.
(E) Specific ring strength A pulp sheet prepared in accordance with the method described in JIS P 8222 "Adjustment method for test hand-made paper" is used for JIS P 8223 "Test hand-made paper-test of physical properties". The measurement was performed in accordance with the method described in JIS P 8126 "Paper and Paperboard-Compressive Strength Test Method-Ring Crash Method" specified in "Method".
The measurement conditions and measurement results are shown in Tables 1 and 2.

From the results, it can be seen that the used paper pulp obtained by the production method according to the embodiment of the present invention has a relatively low ash content and has good quality.

(Other)
The water used in each step of the present embodiment is not particularly limited, and examples thereof include tap water, ion-exchanged water, pure water, distilled water, sewage secondary treated water, sewage highly treated water, industrial water, and alkaline ionized water. , Vanadium water, hydrogen water, reduced water, hot spring water, deep ocean water, carbonated water, distilled water, silica water, oxygen water, water mixed with substances, water in which chemicals and reagents are dissolved, and other water Can be used. These waters usually contain a calcium content typified by calcium ions. The calcium content refers to, for example, a solution in which Ca2 ⁺ is dissolved and a precipitated calcium salt, but is not limited thereto.

The average particle size described in the present specification is measured by the measuring method specified in JIS Z8825: 2013.

The used paper pulp produced by the present invention is not particularly limited, but can be recycled as gypsum board paper, and can be applied as industrial paper such as paperboard and kraft paper. For example, specific examples of industrial paper typified by paperboard include high-grade white paperboard, special white paperboard, white paperboard including white balls, liners, core base paper, paper tube base paper, building material base paper, paper container base paper, and the like. be able to.

9 Adhesive paper 10 Gypsum-containing waste paper 11 Waste paper Pulp raw material 13 Cleaner 13a Input section 13f Discharge section

Claims (6)

It is a method of producing waste paper pulp from waste paper pulp raw materials.
Waste paper, which is a mixture of waste paper containing gypsum and waste paper containing adhesive, is dissociated into a pulp turbid liquid.
A separation step of separating and removing gypsum to which sticky substances have adhered from the pulp turbid liquid to obtain a residue, and
With
The balance is used as waste paper pulp.
A method for producing used paper pulp. The used paper pulp raw material contains 0.1 to 10% by mass of used paper containing gypsum and 0.1 to 5% by mass of used paper containing an adhesive.
The method for producing used paper pulp according to claim 1. An ion sequestering agent is added to at least one of the disintegration step and the separation step.
The method for producing used paper pulp according to claim 1 or 2. The used paper containing the gypsum content is obtained by crushing the gypsum to which the paper is attached.
The fine gypsum generated when the gypsum is crushed is put into at least one of the disintegration step and the separation step.
The method for producing used paper pulp according to any one of claims 1 to 3. A pulp turbid liquid made of a waste paper pulp raw material obtained by mixing 0.1 to 10% by mass of waste paper containing gypsum and 0.1 to 5% by mass of waste paper containing an adhesive is used as a raw material.
The amount of gypsum is 30 mL / 100 g or more.
Waste paper pulp characterized by that. Freeness is 360 mL-580 mL,
The specific burst strength is 14 (N · cm ² ) × 100 / (g / m ² ) to 30 (N · cm ² ) × 100 / (g / m ² ).
Specific ring strength is ^{132N · m 2 / g · 100~206N} · m 2 / g · 100,
The ash content is 10.0% to 25.0%,
The 6-cut residue is 0.1% to 6.0%,
The used paper pulp according to claim 5.

Images