KR102628687B1 - Manufacturing method of pulp sheet and dehydration enhancer for pulp slurry - Google Patents

Abstract

The present invention provides a method for manufacturing a pulp sheet that can sufficiently lower the moisture content before the dryer part, and a dehydration enhancer for pulp slurry.
A method of producing a pulp sheet by dehydrating a pulp slurry by passing it through a wire part, a press part, and a dryer part, wherein the pulp slurry contains an ether-type nonionic surfactant, and an ether-type nonionic surfactant. A dehydration enhancer for pulp slurry containing a surfactant, wherein the ether-type nonionic surfactant is a homopolymer of polyoxypropylene or a copolymer having a polyoxyethylene chain and a polyoxypropylene chain as structural units, and the above-mentioned copolymer It is a dehydration improver for pulp slurry with a combined polyoxypropylene chain content of 85% by mass or more.

Description

Manufacturing method of pulp sheet and dehydration enhancer for pulp slurry

The present invention relates to a method for producing pulp sheets and a dehydration enhancer for pulp slurry.

Pulp produced in a pulp mill is processed into a sheet and stored as a pulp sheet. A drying method for pulp sheets includes heat drying, but drying by heating alone is not preferable from the viewpoint of manufacturing costs because it increases fuel consumption.

Therefore, the pulp sheet is usually dehydrated by passing through the wire part, press part, and dryer part, but since the pulp sheet is used by re-isolating and is required to be easy to unwind, dewatering by applying large pressure, such as in a paper machine, is not usually performed. . In other words, dehydration is performed gently in the press part, and moisture needs to be evaporated in the subsequent dryer part (drying process), which requires heat. Specifically, a large amount of fuel such as heavy oil is required.

As a conventional method, in order to improve water permeability (dewaterability) in the press part of a papermaking machine, an organic polymer is added to the pulp slurry to form floc, thereby improving water permeability. I'm losing. In other words, this is a method of improving drainage by coagulating pulp using an organic polymer as a coagulant to form floc. To produce floc, a variety of processing methods are known, such as combining an organic polymer with an inorganic material such as colloidal silica (Non-Patent Document 1).

However, in machines that manufacture pulp sheets sold as pulp raw materials, the addition of organic polymers that change the charging state of the pulp and colloidal silica that forms scale is undesirable because it affects the quality of the pulp.

Non-patent Document 1: Journal of the Paper and Pulp Technology Association (JAPAN TAPPI JOURNAL), February 2004 issue, page 9

As described above, in the papermaking method using a papermaking machine, the organic polymer used for dewatering affects the quality of the pulp, so it is not appropriate to apply it to the manufacturing method of pulp sheets. Therefore, it becomes difficult to lower the moisture content of the sheet-like pulp before the dryer part, and a large amount of heat is required for evaporation of moisture in the dryer part, which requires a large amount of fuel such as heavy oil, for example.

In addition, in this specification, the pulp before passing through the dryer part is referred to as sheet-like pulp, and the pulp after passing through the dryer part and drying is referred to as pulp sheet.

In view of the above problem, the present invention is a method of manufacturing a pulp sheet by dehydrating a pulp slurry by passing it through a wire part, a press part, and a dryer part, wherein the moisture content (in the state of sheet-like pulp) is lowered before the dryer part. The purpose is to provide a method for manufacturing a pulp sheet and a dehydration enhancer for pulp slurry.

That is, the present invention provides the following (1) to (9).

(1) A method of producing a pulp sheet by dehydrating a pulp slurry by passing it through a wire part, a press part, and a dryer part, wherein the pulp slurry contains an ether-type nonionic surfactant.

(2) The method for producing a pulp sheet according to (1) above, wherein the nonionic surfactant is a polymer having at least one of a polyoxypropylene chain and a polyoxybutylene chain as a structural unit.

(3) The method for producing a pulp sheet according to (1) or (2) above, wherein the nonionic surfactant is a copolymer having a polyoxyethylene chain and a polyoxypropylene chain as structural units.

(4) The method for producing the pulp sheet according to (3) above, wherein the content of polyoxypropylene chains in the copolymer is 85% by mass or more.

(5) The method for producing a pulp sheet according to (3) or (4) above, wherein the copolymer is a block copolymer represented by the following formula (I) or (II).

R ¹ O―(C ₂ H ₄ O) _a ―(C ₃ H ₆ O) _b ―(C ₂ H ₄ O) _c ―R ² … (Ⅰ)

(In the formula, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, a+c is 1 to 10, and b is 5 to 40.)

R ³ O―(C ₃ H ₆ O) _d ―(C ₂ H ₄ O) _e ―(C ₃ H ₆ O) _f ―R ⁴ … (Ⅱ)

(In the formula, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, e is 1 to 10, and d + f is 5 to 40.)

(6) The method for producing a pulp sheet according to (1) or (2) above, wherein the nonionic surfactant is a homopolymer of polyoxypropylene.

(7) The method for producing a pulp sheet according to (6) above, wherein the homopolymer of polyoxypropylene is a polymer represented by the following formula (III).

R ⁵ O—(C ₃ H ₆ O) _g —R ⁶ … (Ⅲ)

(In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, and g is 5 to 20)

(8) A dehydration enhancer for pulp slurry containing an ether-type nonionic surfactant, wherein the ether-type nonionic surfactant is a homopolymer of polyoxypropylene or a polyoxyethylene chain and a polyoxypropylene chain in the structural unit. A dehydration improver for pulp slurry, which is a copolymer comprising a polyoxypropylene chain content of 85% by mass or more.

(9) The dehydration improver for pulp slurry according to (8) above, wherein the copolymer is a block copolymer represented by the following formula (I) or (II), or the homopolymer is a homopolymer represented by the following formula (III) .

R ¹ O―(C ₂ H ₄ O) _a ―(C ₃ H ₆ O) _b ―(C ₂ H ₄ O) _c ―R ² … (Ⅰ)

(In the formula, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, a+c is 1 to 10, and b is 5 to 40.)

R ³ O―(C ₃ H ₆ O) _d ―(C ₂ H ₄ O) _e ―(C ₃ H ₆ O) _f ―R ⁴ … (Ⅱ)

(In the formula, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, e is 1 to 10, and d + f is 5 to 40.)

R ⁵ O—(C ₃ H ₆ O) _g —R ⁶ … (Ⅲ)

(In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, and g is 5 to 20)

According to the present invention, in the method of manufacturing a pulp sheet by dehydrating the pulp slurry by passing it through a wire part, a press part, and a dryer part, a method of manufacturing a pulp sheet capable of sufficiently lowering the moisture content before the dryer part and dehydration for pulp slurry Enhancers can be provided.

1 is a schematic diagram showing the manufacturing process of a pulp sheet.

The method for producing a pulp sheet of the present invention is to dehydrate the pulp slurry by passing it through a wire part, a press part, and a dryer part in forming a pulp sheet from a pulp slurry, wherein the pulp slurry contains an ether-type nonionic surfactant. Contains.

(Non-ionic surfactant)

The ether-type nonionic surfactant used in the present invention can be obtained by adding ethylene oxide or the like to a raw material having a hydroxyl group such as a higher alcohol or alkyl phenol, and includes polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether. , polyoxypropylene alkyl ether, etc. In addition, polyoxyethylene polyoxypropylene glycol, etc., which use polypropylene glycol as a hydrophobic group, also fall into the category of the ether-type nonionic surfactant.

The ether-type nonionic surfactant used in the present invention is preferably a polymer having as a structural unit at least one of a hydrophobic polyoxypropylene chain and a polyoxybutylene chain. In particular, a copolymer (hereinafter referred to as “POEO copolymer”) having a polyoxypropylene chain (hereinafter sometimes referred to as “PO”) and a polyoxyethylene chain (hereinafter sometimes referred to as “EO”) It may be described), and especially, a copolymer with a PO content of 85% by mass or more is preferable. Additionally, a homopolymer of propylene oxide (hereinafter sometimes referred to as “PO homopolymer”) containing 100% by mass of PO, that is, consisting only of polyoxypropylene chains, is also a preferred embodiment.

The POEO copolymer may be a random copolymer or a block copolymer, but a block copolymer is preferable from the viewpoint of fixation to the pulp. POEO copolymers can be used individually or in combination of two or more.

Additionally, there is no particular limitation regarding the structure of the terminal, and it may be a hydrogen atom or an alkyl group. Suitable specific structures include the following.

R ¹ O―(C ₂ H ₄ O) _a ―(C ₃ H ₆ O) _b ―(C ₂ H ₄ O) _c ―R ² … (Ⅰ)

(In the formula, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, a+c is 1 to 10, and b is 5 to 40.)

R ³ O―(C ₃ H ₆ O) _d ―(C ₂ H ₄ O) _e ―(C ₃ H ₆ O) _f ―R ⁴ … (Ⅱ)

(In the formula, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, e is 1 to 10, and d + f is 5 to 40.)

R ⁵ O—(C ₃ H ₆ O) _g —R ⁶ … (Ⅲ)

(In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, and g is 5 to 20)

In the above formulas (I) to (III), it is preferable that at least one terminal (R ² , R ⁴ and R ⁶ ) is a hydrogen atom, and it is more preferable that both terminals (R ¹ to ^{R 6} ) are hydrogen atoms. . On the other hand, when the terminal is an alkyl group, it is preferable that one terminal (R ¹ , R ³ and R ⁵ ) is an alkyl group and the other terminal (R ² , R ⁴ and R ⁶ ) is a hydrogen atom. The number of carbon atoms of the alkyl group at the terminal is preferably 1 to 28, and more preferably 1 to 18.

Moreover, the average molecular weight is preferably in the range of 300 to 3000, and more preferably in the range of 400 to 2500 in number average molecular weight. In addition, the number average molecular weight is the molecular weight measured by GPC (Gel Permeation Chromatography) and converted using polystyrene as a standard material.

Preferred embodiments of the ether-type nonionic surfactant in which both terminals are hydrogen atoms include triblock copolymers of PO and EO represented by the following formula (I') or (II'), and also by formula (III') PO homopolymers represented by .

HO—(C ₂ H ₄ O) _a —(C ₃ H ₆ O) _b —(C ₂ H ₄ O) _c —H … (Ⅰ')

HO―(C ₃ H ₆ O) _d ―(C ₂ H ₄ O) _e ―(C ₃ H ₆ O) _f ―H … (Ⅱ')

HO―(C ₃ H ₆ O) _g ―H... (Ⅲ')

In the above formula (I'), a+c is 1 to 10, and b is 5 to 40. Moreover, in the above formula (II'), e is 1 to 10, and d+f is 5 to 40. In the above formula (III'), g is 1 to 40, preferably 5 to 20.

The POEO block copolymer having the structure represented by the formula (I') can be obtained, for example, by adding ethylene oxide to propylene oxide having hydroxy groups at both ends.

In addition, the POEO block copolymer having the structure represented by the above formula (II') can be obtained, for example, by causing an addition reaction of propylene oxide to ethylene oxide having hydroxy groups at both ends.

The propylene oxide polymer having the structure represented by the above formula (III') can be obtained, for example, by subjecting propylene oxide to anion ring-opening polymerization.

(Manufacturing method of pulp sheet)

Below, the manufacturing method of the pulp sheet is explained using Figure 1. 1 is a schematic diagram showing a method of manufacturing a pulp sheet from pulp slurry. In the above process, a pulp slurry is manufactured and a pulp sheet is manufactured from the pulp slurry. That is, it includes a raw material preparation process (pulp slurry manufacturing process) (10) and a pulp sheet manufacturing process (20).

First, in the raw material preparation process 10, pulp and water are introduced into the pulp receiving tank 14 to prepare pulp slurry. In addition, water is supplied from the pit 11, but in the pit 11, the filtrate recovered in the pulp sheet manufacturing process 20, which will be described later, may be refluxed and reused (not shown in the drawing).

Next, in the pulp sheet manufacturing process 20, the pulp slurry is formed into a sheet by the sheet machine 21 (sheet-shaped pulp 30), and then into wire parts 22 and press parts. It is dehydrated in (23) and the dryer part (24) to form a pulp sheet.

<Pulp slurry>

Pulp slurry is a liquid obtained by suspending pulp in water, and the concentration of the insoluble suspension is usually about 0.2 to 2.0 mass%, preferably 0.5 to 1.5 mass%, more preferably 0.7. It is ~1.3 mass%.

The surfactant can be added to the pulp slurry, the sheet machine 21 described later, the chest 15 for storing the pulp slurry, but it is easier to manufacture by adding it to the pulp slurry in the pulp receiving tank 14. It is desirable from this point of view.

The amount of surfactant added is preferably 0.001 to 0.1% by mass, more preferably 0.005 to 0.05% by mass, and particularly preferably 0.01 to 0.02% by mass, based on the insoluble suspension contained in the pulp slurry.

Additionally, additives commonly used in the production of pulp sheets may be added to the pulp slurry to the extent that they do not impair the effect of the present invention, for example, pH adjusters, preservatives, softeners, antistatic agents, antifoaming agents, and surfactants other than the above. surfactants, etc. are mentioned. These additives are usually supplied from the first addition device 60 or the second addition device 70 through the first chemical injection pipe 61 and the second chemical injection pipe 71, respectively.

<Wire parts>

The wire part 22 is provided with a wire conveyor in the form of a wire mesh for dewatering the sheet-shaped pulp 30 formed by the sheet machine 21 and sending it to the press part 23. The sheet-shaped pulp 30 is dehydrated by gravity or vacuum dehydrated on a wire conveyor.

<Press part>

The press part 23 is composed of a belt conveyor, and the sheet-like pulp 30 is pressed and dehydrated by sandwiching it between opposing rolls. In this press dehydration process, in the case of ordinary paper, it is desirable to dehydrate as much as possible before the dryer part at high pressure, but in the present invention, since it is used by re-disassembling as described above, it is required to be easy to unwind. , it is not desirable to dehydrate by applying high pressure. Therefore, in the case of ordinary papermaking, pressure is applied so that the moisture content at the exit of the press part is 55 to 45%, but in the present invention, the paper is pressed at a pressure so that the moisture content at the exit of the press part is about 60%.

<Dryer parts>

In the dryer part 24, heat drying of sheet-shaped pulp is performed. There is no particular limitation as a heating method, and a hot air dryer, IR dryer, cylinder dryer, etc. can be used. In the present invention, the moisture content of the final pulp sheet is preferably 10 to 25%, and more preferably 15 to 20%.

(Method of measuring moisture content)

Methods for measuring moisture content include a dryer method, a heat drying method using infrared rays, and a near infrared ray method.

The method using a dryer is conducted in accordance with JIS P 8202, which tests the absolute dry matter content of pulp. A sample is collected and left in a constant temperature heating dryer at 105°C overnight to dry. It is later returned to room temperature in a desiccator and measured by determining the moisture content from the weight difference of the sample before and after drying.

The method of heat drying using infrared rays can quickly measure moisture content. For example, a sample is placed in “Kurigansui” (brand name) manufactured by Kurita Water Industries Ltd., and the water content is measured from the change in mass due to evaporation of water by irradiating it with infrared rays. .

The near-infrared method is performed using, for example, a near-infrared moisture meter "KJT-130" (brand name) manufactured by Kett Electric Laboratory Co., Ltd. Near-infrared rays have a longer wavelength than visible rays, are light outside the red range that cannot be seen by the eye, and are easily absorbed by moisture. Therefore, water content is measured by irradiating light containing near-infrared rays and measuring the reflectance.

(Example)

(Example 1)

A slurry of long coniferous pulp (NBKP) was used, a surfactant represented by the following formula (A) was added at 0.02% by mass based on the insoluble suspension contained in the pulp slurry, and a dynamic water barrier tester “DDA (Dynamic Drainage Analyzer)” was used. 」(manufactured by AB Akribi Kemikonsulter) was used to obtain sheet-like pulp. Additionally, the polyoxypropylene chain content ratio (PO/(PO+EO), mass ratio) of the surfactant is 0.90.

HO—(C ₂ H ₄ O) _a —(C ₃ H ₆ O) _b —(C ₂ H ₄ O) _c —H … (A)

(a+c and b are 5 and 35, respectively)

Next, the sheet-like pulp was sandwiched between the wire and filter paper using a press dehydration tester “Square Sheet Machine Press No. 2570” (manufactured by KUMAGAI RIKI KOGYO Co., Ltd.) and subjected to 3.5 After pressurizing at kg/cm2 for 10 seconds, the moisture content of the sheet-like pulp was measured. The results are shown in Table 1. Additionally, the moisture content was measured using a dryer. The same applies to Examples 2 to 4, Comparative Example 1, and Reference Example 1 below.

(Example 2)

Sheet-shaped pulp was obtained in the same manner as in Example 1, except that the surfactant represented by the following formula (B) was used as the surfactant in Example 1, and the water content of the sheet-shaped pulp was measured. The results are shown in Table 1.

HO―(C ₃ H ₆ O) _g ―H... (B)

(g is 7)

(Example 3)

Sheet-shaped pulp was obtained in the same manner as in Example 1, except that the surfactant represented by the following formula (C) was used as the surfactant in Example 1, and the water content of the sheet-shaped pulp was measured. The results are shown in Table 1. Additionally, the polyoxypropylene chain content ratio (PO/(PO+EO), mass ratio) of the surfactant is 0.89.

HO―(C ₂ H ₄ O) _d ―(C ₃ H ₆ O) _e ―(C ₂ H ₄ O) _f ―H … (C)

(d+f and e are 5 and 30, respectively)

(Example 4)

Sheet-shaped pulp was obtained in the same manner as in Example 1, except that the surfactant represented by the following formula (D) was used as the surfactant in Example 1, and the water content of the sheet-shaped pulp was measured. The results are shown in Table 1. Additionally, the polyoxypropylene chain content ratio (PO/(PO+EO), mass ratio) of the surfactant is 0.80.

HO―(C ₂ H ₄ O) _h ―(C ₃ H ₆ O) _i ―(C ₂ H ₄ O) _j ―H … (D)

(h+j and i are 10 and 30, respectively)

(Comparative Example 1)

Sheet-shaped pulp was obtained in the same manner as in Example 1, except that no surfactant was added, and the water content of the sheet-shaped pulp was measured. The results are shown in Table 1.

(Reference example 1)

Sheet-shaped pulp was obtained in the same manner as in Example 1, except that a cationic organic polymer (Kurita Kogyo Co., Ltd. product, “Hiholder (registered trademark) 821”) was used, and the water content of the sheet-shaped pulp was measured. . The results are shown in Table 1.

Additionally, cationic organic polymers are aggregated when the anionic portion of the pulp fiber reacts with the cationic group of the polymer. Although it is used in papermaking machines, its use is discouraged in the production of sheet-shaped pulp sold as a raw material because it affects the quality of the pulp. It is shown as a reference to the effect.

As clearly shown in Table 1, the water content after press dehydration can be reduced by using the nonionic surfactant of the present invention. In particular, it can be seen that Examples 1 and 2, which have a large PO ratio (hydrophobic portion ratio), exhibit excellent dehydration performance even compared to the cationic organic polymer (Reference Example 1) used in papermaking machines.

10: Raw material preparation process
11 : Feet
14: Pulp receiving tank
15: Chest
20: Pulp sheet manufacturing process
21: Seat machine
22: Wire part
23: press part
24: Dryer part
30: Sheet-like pulp
31: First Europavilion
32: Second Europavilion
60: first addition device
61: First chemical injection pipe
70: Second addition device
71: Second chemical injection pipe

Claims (9)

A method of producing a pulp sheet by dehydrating a pulp slurry by passing it through a wire part, a press part, and a dryer part, wherein the pulp slurry contains an ether-type nonionic surfactant, and the nonionic surfactant is polyoxypropylene. A method of producing a pulp sheet, characterized in that it is a homopolymer.
According to paragraph 1,
A method for producing a pulp sheet wherein the homopolymer of polyoxypropylene is a polymer represented by the following formula (III).
R ⁵ O—(C ₃ H ₆ O) _g —R ⁶ … (Ⅲ)
(In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, and g is 5 to 20)
A dehydration improver for pulp slurry containing an ether-type nonionic surfactant, wherein the ether-type nonionic surfactant is a homopolymer of polyoxypropylene.
According to paragraph 3,
A dehydration improver for pulp slurry, wherein the homopolymer is a homopolymer represented by the following formula (III).
R ⁵ O—(C ₃ H ₆ O) _g —R ⁶ … (Ⅲ)
(In the formula, R ⁵ and R ⁶ are each independently a hydrogen atom or an alkyl group having 1 to 28 carbon atoms, and g is 5 to 20)

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