WO2019123765A1

WO2019123765A1 - Recycled pulp fiber manufacturing method, use of peracid for inactivating and degrading high water-absorption polymer, and peracid-containing agent for inactivating and degrading high water-absorption polymer

Info

Publication number: WO2019123765A1
Application number: PCT/JP2018/036906
Authority: WO
Inventors: 孝義小西
Original assignee: ユニ・チャーム株式会社
Priority date: 2017-12-20
Filing date: 2018-10-02
Publication date: 2019-06-27
Also published as: JP2019108640A; JP6847028B2

Abstract

The purpose of the present invention is to provide a recycled pulp fiber manufacturing method with which it is possible to easily inactivate and degrade a high water-absorption polymer using a single chemical. This method is for manufacturing recycled pulp fibers from used sanitary goods containing pulp fibers and high water-absorption polymer, and is characterized by comprising: a high water-absorption polymer inactivation and degradation step (S1) for immersing a sanitary goods constituent material containing the pulp fibers and an acid radical-containing high water-absorption polymer in a peracid-containing aqueous solution so as to inactivate and degrade the high water-absorption polymer; and a recycled pulp fiber recovery step (S2) for recovering the recycled pulp fibers from the peracid-containing aqueous solution that has undergone the high water-absorption polymer inactivation and degradation step (S1).

Description

Process for the production of recycled pulp fibers, the use of peracids for the deactivation and degradation of superabsorbent polymers, and superabsorbent polymer inactivation and degradation agents comprising peracids

The present disclosure relates to a process for the production of recycled pulp fibers, the use of peracids for the inactivation and degradation of superabsorbent polymers, and inactivation and degradation agents for superabsorbent polymers comprising peracids.

Methods are known for recovering recycled pulp fibers from used sanitary products.
For example, Patent Document 1 discloses a method of recovering pulp fibers from used sanitary products containing pulp fibers and super absorbent polymer, and producing recycled pulp reusable as a sanitary product, which method is used Used sanitary articles are pulp fibers and other articles by applying physical force to used sanitary products in an aqueous solution containing polyvalent metal ions or an acidic aqueous solution having a pH of 2.5 or less. The process of decomposing into materials, the process of separating pulp fibers from the mixture of pulp fibers and other materials generated in the decomposition process, and the process of treating the separated pulp fibers with an ozone-containing aqueous solution having a pH of 2.5 or less A method is disclosed characterized in that.

JP, 2016-881, A

In Patent Document 1, a step of deactivating a superabsorbent polymer using an aqueous solution containing polyvalent metal ions or an acidic aqueous solution having a pH of 2.5 or less, and an ozone-containing aqueous solution having a pH of 2.5 or less And a step of decomposing the activated superabsorbent polymer with a plurality of different agents, ie, an aqueous solution containing a divalent metal ion or an acidic aqueous solution having a pH of 2.5 or less (specifically, a polyvalent metal ion or acid). Since an ozone-containing aqueous solution (specifically, ozone) having a pH of 2.5 or less is responsible, it is necessary to separately manage them, and there is room for improvement from the viewpoint of manufacturability. Moreover, in order to form ozone containing aqueous solution, since mechanical installation, such as an ozone generator, is required, there exists a tendency for a manufacturing installation to become large.
Accordingly, the present disclosure aims to provide a method for producing recycled pulp fibers in which the inactivation and degradation of superabsorbent polymer can be easily carried out using a single agent.

The present inventors are a method of producing recycled pulp fibers from used sanitary products, comprising pulp fibers and a superabsorbent polymer, comprising the pulp fibers and a superabsorbent polymer having an acid group. The hygienic article constituent material which constitutes the above-mentioned hygienic article is immersed in a peroxy acid containing aqueous solution containing a peroxy acid to inactivate the above-mentioned super absorbent polymer, and at the same time the super absorbent polymer is deactivated which decomposes the above super absorbent polymer It has been found that the method includes a decomposition step, and a recycled pulp fiber recovery step of recovering the recycled pulp fibers from the peroxy acid-containing aqueous solution subjected to the superabsorbent polymer inactivation and decomposition step.

The method for producing recycled pulp fibers of the present disclosure can easily carry out the inactivation and decomposition of the superabsorbent polymer using a single agent.

FIG. 1 is a block diagram of a system 1 for implementing the method according to one of the embodiments of the present disclosure. FIG. 2 is a schematic view showing a configuration example of the bag removing device 11 and the crushing device 12 of FIG. FIG. 3 is a flow chart illustrating a method of using the system 1 to produce recycled pulp fibers from used sanitary products.

<Definition>
・ "Inactivation" related to super absorbent polymer
In the present specification, “inactivation” with respect to a super absorbent polymer (Super Absorbent Polymer, SAP) is preferably 50 times or less, more preferably 30 times or less, of the super absorbent polymer retaining excrement and the like. More preferably, adjustment is made to have an absorption capacity of 25 times or less, for example, release of retained excrement, suppression of absorption of a peracid-containing aqueous solution, and the like.

The absorption capacity is measured as follows.
(1) The inactivated super absorbent polymer is put into a mesh and suspended for 5 minutes to remove water adhering to the surface thereof, and the mass before drying: m ₁ (g) is measured.
(2) The inactivated superabsorbent polymer is dried at 120 ° C. for 10 minutes, and the mass after drying: m ₂ (g) is measured.
(3) Absorption capacity (g / g), the following formula:
Absorption capacity _{(g / g) = m 1} / m 2
Calculated by

・ "Peroxy acid containing aqueous solution"
As used herein, "peracid-containing aqueous solution" means an aqueous solution containing a peracid and / or a peracid-derived acid.
In the superabsorbent polymer inactivation and decomposition step, the peroxy acid-containing aqueous solution at the time of immersing the sanitary product component constituting the sanitary product contains a peracid.
Furthermore, in the superabsorbent polymer inactivation and decomposition step, the peracid-containing aqueous solution after decomposing the superabsorbent polymer, and the peracid-containing aqueous solution in the recycled pulp fiber recovery step are peracids depending on the degree of consumption of the peracid. The acid contained in the contained aqueous solution may vary. Specifically, when the peracid oxidizes the superabsorbent polymer and the like and is completely consumed, the peracid-containing aqueous solution contains no peracid and contains a peracid-derived acid. In addition, when the peracid oxidizes the superabsorbent polymer and the like but is not completely consumed, the peracid-containing aqueous solution contains a peracid and a peracid-derived acid.

Specifically, the present disclosure relates to the following aspects.
[Aspect 1]
A method of producing recycled pulp fibers from used sanitary goods comprising pulp fibers and superabsorbent polymers, comprising:
The hygienic article constituent material which constitutes the above-mentioned hygienic goods which contains the above-mentioned pulp fiber and the super-absorbent polymer which has an acid group is immersed in the peroxy acid containing aqueous solution containing peroxy acid, and the above-mentioned super-absorbent polymer is inactivated. Superabsorbent polymer inactivation and decomposition steps to degrade said superabsorbent polymer,
A recycling pulp fiber recovery step of recovering the recycling pulp fiber from the peroxy acid-containing aqueous solution subjected to the superabsorbent polymer inactivation and decomposition step;
Said method, characterized in that it comprises.

In the above method, in the superabsorbent polymer inactivation and decomposition step, the peracid (and the peracid-derived acid generated from the peracid) not only acts as an inactivating agent that inactivates the superabsorbent polymer. Since the peracid also acts as a decomposing agent capable of decomposing the superabsorbent polymer, and inactivation and degradation of the superabsorbent polymer can be carried out in a single step, the productivity of recycled pulp fibers can be increased. Excellent.

[Aspect 2]
The method according to embodiment 1, wherein said peracid has a smaller acid dissociation constant (pK _a , in water) than said acid groups of said superabsorbent polymer.

In the above method, since the peracid has an acid dissociation constant (pK _a , in water) smaller than the acid group of the superabsorbent polymer, the peracid before oxidizing the superabsorbent polymer is not a superabsorbent polymer. It can have a higher effect as an activating inactivating agent.

[Aspect 3]
The peracid from the acid generated from the peracid has the superabsorbent small acid dissociation constant than the acid group of the polymer (pK _a, water), method according to embodiment 1 or 2.

In the above method, the peracid derived acids, because it has a high water-absorbing polymers a small acid dissociation constant than acid groups (pK _a, water), peracids derived acid produced after the peracid to oxidize the superabsorbent polymer However, it can have a higher action as an inactivating agent for inactivating superabsorbent polymers.

[Aspect 4]
The above-mentioned hygienic goods constituent material is the above-mentioned hygienic goods,
After the above-mentioned method immerses the above-mentioned hygienic article constituent material in the above-mentioned peroxy acid containing aqueous solution in the above-mentioned super absorbent polymer inactivation and decomposition step, the above-mentioned pulp fiber and super-absorbent polymer are removed among the above-mentioned hygienic article constituent materials Further including a removal step for removing
In the superabsorbent polymer inactivation and decomposition step, after the removal step, a peracid is added to the peracid-containing aqueous solution,
The method according to any one of Aspects 1-3.

In the above method, the sanitary product component material to be immersed in the aqueous solution containing the peroxy acid is a sanitary product, and the pulp fiber and the highly water-absorptive polymer of the component products can be used in the above-mentioned superabsorbent polymer inactivation and decomposition steps. The method further includes a removal step of removing anything, and since the peracid is added to the peracid-containing aqueous solution after the removal step, the peracid can effectively decompose the superabsorbent polymer as a decomposing agent.

[Aspect 5]
The above-mentioned hygienic goods constituent material is the above-mentioned hygienic goods,
After the above-mentioned method immerses the above-mentioned hygienic article constituent material in the above-mentioned peroxy acid containing aqueous solution in the above-mentioned super absorbent polymer inactivation and decomposition step, the above-mentioned pulp fiber and super-absorbent polymer are removed among the above-mentioned hygienic article constituent materials Further including a removal step for removing
After the removal step in the superabsorbent polymer inactivation and decomposition step, raising the temperature of the peroxy acid-containing aqueous solution,
The method according to any one of aspects 1-4.

In the above method, the sanitary product component material to be immersed in the aqueous solution containing the peroxy acid is a sanitary product, and the pulp fiber and the highly water-absorptive polymer of the component products can be used in the above-mentioned superabsorbent polymer inactivation and decomposition steps. The method further includes a removal step of removing anything, and the temperature of the aqueous solution containing peracid is increased after the removal step, so that the peracid acts as a decomposing agent, that is, the oxidation of the superabsorbent polymer, and the superabsorbent It can promote the degradation of the polymer.

[Aspect 6]
The method according to any one of modes 1 to 5, wherein in the recycled pulp fiber recovery step, the recycled pulp fiber is left with a peracid-derived acid generated from the peracid.

In the above method, in the recycling pulp fiber recovery step, since the peracid-derived acid generated from the peracid is left in the recycling pulp fiber, the recycling pulp fiber can be provided with an antimicrobial property.

[Aspect 7]
Use of peracids for the deactivation and degradation of superabsorbent polymers with acid groups.

In the above use, the peracid (and the peroxyacid derived acid) not only acts as an inactivating agent that inactivates the super absorbent polymer, but also that the peracid acts as a decomposing agent that degrades the super absorbent polymer Can.

[Aspect 8]
An activating and decomposing agent for a superabsorbent polymer having an acid group, which comprises a peracid.

The above-mentioned inactivating and decomposing agents can not only inactivate the superabsorbent polymer but also decompose the superabsorbent polymer.

The process for producing recycled pulp fibers of the present disclosure, the use of peracids for deactivating and decomposing superabsorbent polymers, and the deactivating and decomposing agents for superabsorbent polymers containing peracids are described in detail below. explain.

<< Production method of recycled pulp fiber >>
A method of producing recycled pulp fibers from used sanitary goods including the pulp fiber of the present disclosure and the superabsorbent polymer (hereinafter referred to as “the method of producing the recycled pulp fiber”, “the production method of the present disclosure”, etc.) A) includes the following steps.
-The sanitary goods constituent material which constitutes the above-mentioned hygiene goods which contains the above-mentioned pulp fiber and a super-absorbent polymer which has an acid group is immersed in the peroxy acid containing aqueous solution containing peroxy acid, and the above-mentioned superabsorbent polymer is inactivated. Superabsorbent polymer inactivation and decomposition step (hereinafter referred to as "superabsorbent polymer inactivation and decomposition step")
・ Recycled pulp fiber recovery step (hereinafter sometimes referred to as “recycled pulp fiber recovery step”) which recovers the recycled pulp fiber from the aqueous solution containing peroxy acid which has been subjected to the super absorbent polymer inactivation and decomposition step

<Superabsorbent polymer inactivation and decomposition step>
In the superabsorbent polymer inactivation and decomposition step, the sanitary article construction material containing pulp fibers and the superabsorbent polymer having an acid group is immersed in a peroxy acid containing aqueous solution to inactivate the superabsorbent polymer. Disassemble super absorbent polymer.

As the peracid, a peracid and / or a peracid-derived acid generated from the peracid can act as an inactivating agent for deactivating the superabsorbent polymer, and the peracid is a superabsorbent polymer Is not particularly limited as long as it can act as a decomposing agent that oxidizes and decomposes the superabsorbent polymer, for example, percarboxylic acids (eg, peracetic acid, perbenzoic acid, metachloroperbenzoic acid), Persulfonic acid (eg, persulfuric acid, methanepersulfonic acid, trifluoromethanepersulfonic acid, p-toluenepersulfonic acid), perphosphoric acid and the like, and metal salts thereof and the like can be mentioned.

Examples of the peracid-derived acid (peracid) include carboxylic acids (percarboxylic acids) such as acetic acid (peracetic acid), benzoic acid (perbenzoic acid), metachlorobenzoic acid (metachloroperbenzoic acid), sulfonic acid (Persulfonic acid), for example, sulfuric acid (persulfuric acid), methanesulfonic acid (methanepersulfonic acid), trifluoromethanesulfonic acid (trifluoromethanepersulfonic acid), p-toluenesulfonic acid (p-toluenepersulfonic acid), Phosphoric acid (perphosphoric acid) is mentioned.

The peracid may be added as a mixture of a peracid derived acid and hydrogen peroxide. For example, when the peracid is peracetic acid, the peracid may be added as a mixed aqueous solution of acetic acid which is a peracid-derived acid and hydrogen peroxide. This is from the viewpoint of stably adding (storing) the peracid.

In the production method of the present disclosure, the peracid preferably has _a smaller acid dissociation constant (pKa, in water) than the acid group of the superabsorbent polymer. By doing so, the action of the peracid itself as an inactivating agent can be further enhanced.

When the peracid has a plurality of acid groups, for example, when the peracid is a dibasic acid or a tribasic acid, the largest acid dissociation among the acid dissociation constants (pK _a , water) of the peracids constant (pK _a, water) is, when the acid dissociation constant (pK _a, water) of the acid groups of the superabsorbent polymer is preferably smaller than, and the superabsorbent polymer has a plurality of types of acid groups, the acid dissociation constant (pK _a in water) peracids greatest acid dissociation constant (pK _a in water) out of the smallest acid dissociation constant (pK _a of the superabsorbent polymer is more acid groups, in water It is preferable that it is smaller than. It is from the viewpoint of the inactivation efficiency of the super absorbent polymer.

In the production method of the present disclosure, it is preferable that the peracid-derived acid generated from the peracid have an acid dissociation constant (pK _a , in water) smaller than the acid group of the superabsorbent polymer. By doing so, when the peracid oxidizes the superabsorbent polymer and generates a peracid-derived acid, the peracid derived acid acts more as an inactivating agent that inactivates the superabsorbent polymer. It can have.

When the peracid-derived acid has a plurality of acid groups, for example, when the peracid-derived acid is a dibasic acid or a tribasic acid, the acid dissociation constant of the peracid-derived acid (pK _a , in water) the biggest acid dissociation constant (pK _a, water) is an acid dissociation constant (pK _a, water) of the acid groups of the superabsorbent polymer is preferably smaller than, and acid superabsorbent polymer is more of If with the above-mentioned acid dissociation constant of peracid from the acid (pK _a, water) the largest acid dissociation constant of (pK _a, water) is, the superabsorbent polymer is smallest among the plurality of kinds of groups acid dissociation constant (pK _a, water) is preferably less than. It is from the viewpoint of the inactivation efficiency of the super absorbent polymer.

In the present specification, as the acid dissociation constant (pk _a , in water), the value described in the Electrochemical Handbook edited by the Institute of Electrochemical Society can be adopted.
According to the Electrochemical Handbook, the acid dissociation constants (pk _a , in water, 25 ° C.) of the major compounds are as follows:
[Organic acid]
- tartaric _{acid: 2.99 (pK a1), 4.44} (pK a2)
- malic _{acid: 3.24 (pK a1), 4.71} (pK a2)
Citric _{acid: 2.87 (pK a1), 4.35} (pK a2), 5.69 (pK a3)
[Inorganic acid]
-Sulfuric acid: 1.99

The acid dissociation constant (pk _a , in water) of an acid not described in the Electrochemical Handbook can be determined by measurement. As an apparatus which can measure the acid dissociation constant (pk _a , in water) of an acid, for example, a compound physical property evaluation analysis system manufactured by Sirius, T3 can be mentioned.

In the production method of the present disclosure, the superabsorbent polymer is not particularly limited as long as it is used in the art as a superabsorbent polymer containing an acid group, and examples of the acid group include carboxyl. Groups, sulfo groups, etc. are mentioned, and a carboxyl group is preferable.
Examples of highly water-absorptive polymers containing a carboxyl group include those of polyacrylates and polyanhydrides, and examples of highly water-absorptive polymers containing sulfo and the like include polysulphonates. It can be mentioned.

The pulp fiber is not particularly limited as long as it can be contained in a sanitary product.

The superabsorbent polymer inactivation and degradation steps are preferably performed at a predetermined pH. The predetermined pH is preferably 4.5 or less, more preferably 4.0 or less, still more preferably 3.5 or less, and still more preferably 3.0 or less. If the predetermined pH is too high, the inactivation of the superabsorbent polymer may be insufficient.
Also, the predetermined pH is preferably 0.5 or more, and more preferably 1.0 or more. If the predetermined pH is too low, the recycled pulp fibers may be damaged.
In addition, the above-mentioned predetermined | prescribed pH means the value in 25 degreeC. The predetermined pH described above can be measured, for example, using twin pH meter AS-711 manufactured by Horiba, Ltd.

In the manufacturing method of the present disclosure, it is preferable to satisfy at least the predetermined pH at the start of the superabsorbent polymer inactivation and decomposition steps, for example, when immersing the sanitary product component in a peroxy acid containing aqueous solution. In order to inactivate the super absorbent polymer, when the super absorbent polymer is not sufficiently inactivated, the production efficiency of the method for producing a recycled pulp of the present disclosure is reduced, and thus recycled pulp fibers to be produced, The super absorbent polymer may remain.

In the production method of the present disclosure, it is preferable that the predetermined pH be satisfied at the end of the superabsorbent polymer inactivation and decomposition steps, for example, when the manufactured recycled pulp fiber is taken out of the aqueous solution containing peracid. This is from the viewpoint of continuing to inactivate the remaining super absorbent polymer, and from the viewpoint of leaving the acid derived from the peroxy acid to the manufactured recycled pulp fiber and imparting the antibacterial property to the recycled pulp fiber.

In the superabsorbent polymer inactivation and decomposition step, for example, a sanitary article construction material containing pulp fiber and superabsorbent polymer is put into a tank filled with a peroxy acid containing aqueous solution, and the peroxy acid containing aqueous solution is treated at room temperature. Stirring for about 5 to 60 minutes at (25 ° C.) can inactivate the superabsorbent polymer, oxidize the superabsorbent polymer, and decompose the superabsorbent polymer.

In the production method of the present disclosure, the specific method is not particularly limited as long as the sanitary product component can be immersed in the peroxy acid-containing aqueous solution. For example, in a tank containing the peroxy acid-containing aqueous solution, the component The peracid-containing aqueous solution may be introduced into the tank in which the sanitary product construction material is disposed.

The sanitary product is not particularly limited as long as it contains pulp fibers and a superabsorbent polymer, and, for example, disposable diapers, disposable shorts, sanitary napkins, panty liners, urine absorbing pads, bed sheets, pets Sheet etc. may be mentioned.
Examples of the above-mentioned sanitary goods include those containing a liquid-permeable sheet, a liquid-impermeable sheet, and an absorbent (absorbent core and core wrap) therebetween.

In the manufacturing method of the present disclosure, the sanitary product component in the superabsorbent polymer inactivation and degradation step is a mixture of pulp fibers and the superabsorbent polymer, for example, an absorbent core removed from a used sanitary product. Can. In addition, the sanitary product component may be the sanitary product itself.

In addition to pulp fiber and super absorbent polymer (hereinafter sometimes referred to as "specific material"), the sanitary goods component material to be immersed in the aqueous solution containing peroxy acid is referred to as additional material (hereinafter "non-specific material") In some cases, for example, when including a liquid-permeable sheet, a liquid-impermeable sheet, etc., for example, when immersing the sanitary goods itself as a sanitary goods constituent material in a peroxy acid containing aqueous solution, a superabsorbent polymer The inactivation and degradation steps can further include a removal substep of removing non-specific material (hereinafter sometimes referred to as "removal substep"). By doing so, the peracid can suppress oxidation of non-specific materials, and the peracid can efficiently oxidize the superabsorbent polymer.

In the removal sub-step, all of the non-specific materials may be removed from the aqueous solution containing the specific materials, but it is practically difficult to remove all of the non-specific materials. A part of non-specific material may remain in the aqueous solution containing peracid.

Specific examples of the removal sub-step will be described later in connection with the system 1 shown in FIG. 1 and the flow chart shown in FIG.

If the superabsorbent polymer inactivation and degradation step further comprises a removal substep, the concentration of peracid in the aqueous solution containing peracid can be increased after performing the removal substep. By doing so, after the removal substep, the action as a decomposing agent by peracid, specifically, the oxidizing power can be increased, and the peracid can efficiently oxidize the superabsorbent polymer.

In the superabsorbent polymer inactivation and decomposition step, after the removal substep, the total molar concentration of peracid and peracid-derived acid (hereinafter "peracidic acid") in the aqueous solution containing peracid is removed The total molar concentration of the peroxyacid in the aqueous solution containing peroxyacid immediately after completion can be increased by preferably 2 to 100 times, more preferably 3 to 50 times, and still more preferably 4 to 20 times. From the above point of view.
Examples of means for increasing the total molar concentration of the peracid acid include concentration of the peracid acid by heating of the peracid-containing aqueous solution, addition of the peracid to the peracid-containing aqueous solution, and the like.

In the superabsorbent polymer inactivation and degradation step, the temperature of the aqueous solution containing peracid may be raised after the removal substep. When the temperature of the peroxy acid-containing aqueous solution is increased, the amount of radicals generated from the peroxyacid increases due to the thermal energy by heating, so the oxidative power of the peroxyacid increases, and the decomposition of the superabsorbent polymer can be promoted. .

The superabsorbent polymer inactivation and decomposition step prior to the removal substep is mainly based on the inactivation of superabsorbent polymer, in other words, the function as the peracid and / or the peracid derived acid as the activator. , For example, at room temperature. When controlling the temperature of the superabsorbent polymer inactivation and degradation step prior to the removal substep, the temperature can preferably be controlled at a temperature of 10 to 30 ° C, more preferably 15 to 25 ° C. By controlling the temperature within the above range, the action of the peracid as a decomposing agent can be suppressed, and the action of the peracid on non-specific materials as a decomposing agent can be suppressed.

In the superabsorbent polymer inactivation and degradation step, after the removal substep, degradation of the superabsorbent polymer predominates, in other words, since the action as a decomposing agent of a peracid is main, for example, before the removal substep In comparison, the temperature can be managed preferably at a temperature of 30 to 70 ° C., more preferably 40 to 60 ° C. higher.

<Recycled pulp fiber recovery step>
In the recycled pulp fiber recovery step, recycled pulp fibers are recovered from the peroxy acid-containing aqueous solution that has undergone the superabsorbent polymer inactivation and decomposition steps.
Recovery of the recycled pulp fiber can be used without particular limitation as long as it is an apparatus capable of solid-liquid separation, and examples of the apparatus capable of solid-liquid separation include a rotary drum screen, an inclined screen, a vibrating screen and the like.

In the recycled pulp fiber recovery step, it is preferable to leave the peracid-derived acid in the recovered recycled pulp fiber. By doing so, it is possible to impart the antibacterial property to the recycled pulp fiber, and for example, even when the recycled pulp fiber is stored in a wet state, it is possible to suppress the growth of mold and the like.

<Use of Peracid for Deactivation and Decomposition of Superabsorbent Polymer>
The present disclosure relates to the use of peracids for the deactivation and degradation of superabsorbent polymers with acid groups. In the above use, the peracid (and the peroxyacid derived acid) not only acts as an inactivating agent that inactivates the super absorbent polymer, but also that the peracid acts as a decomposing agent that degrades the super absorbent polymer Can inactivate and degrade the superabsorbent polymer.

The present disclosure also relates to the use of peracid for producing recycled pulp fibers from sanitary product construction materials comprising pulp fibers and superabsorbent polymers having acid groups. In the above use, the peracid (and the peroxyacid derived acid) not only acts as an inactivating agent that inactivates the super absorbent polymer, but also that the peracid acts as a decomposing agent that degrades the super absorbent polymer Peracid-derived acid can impart antimicrobial properties to the recycled pulp fibers.
Since the said use is demonstrated by "the manufacturing method of recycle pulp fiber", description here is abbreviate | omitted.

<Inactivation and decomposition agent of super absorbent polymer containing peracid>
The present disclosure relates to deactivating and decomposing agents for superabsorbent polymers having acid groups, including peracids. The above-mentioned inactivating and decomposing agents can not only inactivate the superabsorbent polymer but also decompose the superabsorbent polymer.

The present disclosure also relates to a superabsorbent polymer inactivating and decomposing agent in a sanitary product construction material comprising pulp fibers and a superabsorbent polymer having acid groups, comprising a peracid. The above-mentioned inactivating and decomposing agents can not only inactivate the superabsorbent polymer, but can decompose the superabsorbent polymer as well as impart antimicrobial properties to the recycled pulp fibers.
About the said inactivation and decomposition agent, since it is demonstrated by "the manufacturing method of a recycling pulp fiber", description here is abbreviate | omitted.

FIG. 1 is a block diagram of a system 1 for implementing the manufacturing method according to one of the embodiments of the present disclosure. FIG. 1 is a diagram for explaining a manufacturing method according to one of the embodiments of the present disclosure, and does not limit the present disclosure in any way.
The system 1 includes a bag removing device 11, a shredding device 12, a first separating device 13, a first dust removing device 14, a second dust removing device 15, a third dust removing device 16, a disassembling device 17, and a second And a separation device 18.

The bag-breaking device 11 is filled with a peroxy acid-containing aqueous solution, and forms an opening in the collection bag containing used sanitary goods in the peroxy acid-containing aqueous solution. The crusher 12 crushes the used sanitary goods sunk below the surface of the aqueous solution containing the peroxy acid together with the collection bag. FIG. 2 is a schematic view showing a configuration example of the bag removing device 11 and the crushing device 12 of FIG.

The bag-breaking apparatus 11 is filled with a peroxy acid-containing aqueous solution B, forms an opening in the collection bag A that has settled in the peroxy acid-containing aqueous solution B, contains used sanitary goods, A collection bag 91 is formed. The bag-breaking apparatus 11 includes a solution tank V and an aperture forming part 50. The solution tank V stores the peracid-containing aqueous solution B. The hole forming portion 50 is provided in the solution tank V, and when the collection bag A is put in the solution tank V, a hole is formed on the surface of the collection bag A in contact with the aqueous solution B containing peroxy acid. Do.

The hole forming unit 50 includes a feeding unit 30 and a bag opening 40. The feed unit 30 feeds (pulls) the collection bag A (physically and forcibly) into the peroxy acid-containing aqueous solution B in the solution tank V. The feed unit 30 is, for example, a stirrer, and includes a stirring blade 33, a support shaft (rotary shaft) 32 supporting the stirring blade 33, and a drive device 31 rotating the support shaft 32 along an axis. The stirring blade 33 rotates around the rotation shaft (support shaft 32) by the drive device 31 to generate a swirling flow in the peroxy acid-containing aqueous solution B. The feed unit 30 draws the collection bag A toward the bottom of the peroxy acid-containing aqueous solution B (solution tank V) by the swirling flow.

The tear-off portion 40 is disposed at the lower portion (preferably the bottom) of the solution tank V, and the tear-off blade 41, a support shaft (rotation shaft) 42 for supporting the tear-off blade 41, and the support shaft 42 And a driving device 43 which rotates along with it. The tear-off blade 41 forms an opening in the collection bag A moved to the lower part of the aqueous solution B (solution tank V) by rotating around the rotation shaft (support shaft 42) by the drive device 43. .

The crushing apparatus 12 crushes the used sanitary goods in the collection bag A sunk below the surface of the aqueous solution B containing peroxy acid together with the collection bag A. The crushing apparatus 12 includes a crushing unit 60 and a pump 63. The crushing part 60 is connected by the solution tank V and the pipe 61, includes the used sanitary goods discharged from the solution tank V, and includes the collection bag 91 having the opening part, including the collection bag A, including the peroxide The aqueous solution B is crushed to form a peracid-containing aqueous solution 92 containing the crushed material.

The crusher 60 may be a twin-screw crusher (for example, a twin-screw rotary crusher, a twin-screw differential crusher, a twin-screw shear crusher). Company-made). The pump 63 is connected to the crushing unit 60 by a pipe 62, and draws out from the crushing unit 60 the aqueous solution containing peracid containing the crushed material obtained in the crushing unit 60 and delivers it to the next process. However, the crushed material includes materials including pulp fiber, super absorbent polymer, material of collecting bag A, film, non-woven fabric, elastic body and the like.

The first separation device 13 contains the crushed material while stirring the peracid-containing aqueous solution 92 containing the crushed material obtained by the crushing device 12 to remove dirt (excrements etc.) from the crushed material. From the aqueous solution containing peroxy acid 92, the aqueous solution containing peroxy acid 93 containing pulp fibers and super absorbent polymer from which foreign matter has been removed is separated and sent to the first dust removing device.

Examples of the first separation device 13 include a washing tub and a dewatering tub and a washing machine provided with a water tub surrounding the same. However, a washing tank and dewatering tank (rotary drum) is used as a washing tank and sieving tank (separation tank). Examples of the washing machine include a horizontal washing machine ECO-22B (manufactured by Inamoto Seisakusho Co., Ltd.).

The first dust remover 14 further removes foreign matter present in the aqueous solution containing peroxyacid 93 from which foreign matter has been removed by a screen having a plurality of openings, and foreign matter including pulp fiber and superabsorbent polymer is further removed. A peroxy acid-containing aqueous solution 94 is formed. Examples of the first dust remover 14 include a screen separator (coarse screen separator), and specifically, for example, a pack pulper (manufactured by Satomi Seisakusho Co., Ltd.).

The second dust remover 15 removes finer foreign particles from the peroxy acid-containing aqueous solution 94 from the first dust remover 14 which has been removed from the first dust remover 14 by a screen having a plurality of openings, thereby removing pulp fibers and high water absorption. To form a peracid-containing aqueous solution 95 from which foreign substances have been further removed, including a hydrophobic polymer. Examples of the second dust remover 15 include a screen separator, and more specifically, for example, Lamo Screen (manufactured by Aikawa Tekko Co., Ltd.).

The third dust remover 16 further removes foreign matter from the peroxy acid-containing aqueous solution 95 which is sent from the second dust remover 15 by centrifugal separation and from which foreign matter is further removed, and contains pulp fibers and a superabsorbent polymer And forms an aqueous solution containing peracid 96 from which foreign matter is further removed. Examples of the third dust remover 16 include a cyclone separator, specifically, ACT low concentration cleaner (manufactured by Aikawa Iron Works Co., Ltd.).

In the decomposing device 17, the peracid-containing aqueous solution 96 from the third dust removing device 16 from which foreign substances are further removed is heated, and the superabsorbent polymer is oxidized and decomposed by the oxidizing power of the peracid to increase pulp fiber Remove the water absorbing polymer. Then, the peracid-containing aqueous solution 97 containing recycled pulp fibers is discharged.

The second separation device 18 separates the recycled pulp fibers from the peroxy acid-containing aqueous solution 97 containing recycled pulp fibers that has been treated by the decomposition device 17 using a screen having a plurality of openings. Examples of the second separation device 18 include a screen separator.

FIG. 3 is a flow chart illustrating a method of producing recycled pulp fibers from used sanitary products using the system 1 shown in FIG. The flowchart shown in FIG. 3 is an example and does not limit the present disclosure.

FIG. 3 shows the superabsorbent polymer inactivation and decomposition step S1, the removal substep S1 _S , and the recycled pulp fiber recovery step S2. In the superabsorbent polymer inactivation and decomposition step S1, an aperture forming step P11, a crushing step P12, a first separation step P13, a first dust removal step P14, a second dust removal step P15, and a third dust removal The process P16 and the decomposition process P17 are included, and the removal sub-step S1 _S includes the first separation process P13, the first dust removal process P14, the second dust removal process P15, and the third dust removal process P16. Be
The recycled pulp fiber recovery step S2 includes a second separation step P18. The details will be described below.

The opening portion forming step P11 is performed using the bag opening device 11. The collection bag A in which the used sanitary goods are enclosed is put into the solution tank V storing the peracid-containing aqueous solution B, and an opening is formed on the surface of the collection bag A in contact with the peroxy acid-containing aqueous solution B. The aqueous solution B containing peracid has a periphery of the collection bag A so that the dirt, fungi, odor and the like of the used sanitary goods in the collection bag A are not released to the outside when an opening is formed in the collection bag A. Seal around. When the peroxy acid-containing aqueous solution intrudes into the collection bag A from the opening, the gas in the collection bag A escapes to the outside of the collection bag A, and the specific gravity of the collection bag A becomes heavier than the peroxy acid-containing aqueous solution B. A precipitates in the peracid-containing aqueous solution B. In addition, the peracid in the peracid-containing aqueous solution B acts as an inactivating agent, inactivates the superabsorbent polymer in the used sanitary goods in the collection bag A, and acts as a decomposing agent, thereby causing high water absorption. Oxidizable polymer begins to degrade. In addition, a peracid-derived acid generated by oxidizing a hygienic product constituent material such as a superabsorbent polymer or the like by the peracid oxidizes the superabsorbent polymer as an inactivating agent.

The superabsorbent polymer in the used sanitary goods is inactivated and its ability to absorb water is reduced, so that the superabsorbent polymer is dewatered and the particle size is reduced, making it easy to handle in the subsequent steps. Process efficiency is improved. When peracid is used for inactivation, there is an advantage that ash does not remain in the pulp fiber as compared with the case of inactivating the superabsorbent polymer using lime, calcium chloride or the like, and the degree of inactivation (particle diameter, There is an advantage that it is easy to adjust the size of specific gravity etc. by pH.

When the sanitary product construction material to be immersed in the peroxy acid-containing aqueous solution contains a non-specific material such as a liquid permeable sheet, a liquid impermeable sheet, etc., for example, the sanitary product itself as a sanitary product construction material In the case of immersing in a containing aqueous solution, it is preferable that the size, specific gravity, etc., of the pulp fibers constituting the specific material be relatively close to the size, specific gravity, etc. of the superabsorbent polymer. From this point of view also, it is preferable that the peracid-containing aqueous solution have the above-mentioned predetermined pH in the superabsorbent polymer inactivation and decomposition step.

In the bag-breaking apparatus 11 of FIG. 2, the rotation of the stirring blade 33 around the rotation shaft (support shaft 32) generates a swirling flow in the peroxy acid-containing aqueous solution B, and the collection bag A is physically forced to be peracid. It is drawn toward the bottom of the contained aqueous solution B (solution tank V). Then, the collection bag A that has moved to the bottom portion contacts the tear-off blade 41 by the rotation of the tear-off blade 41 around the rotation axis (support shaft 42), and an opening is formed in the collection bag A .

The crushing process P12 is performed by the crushing apparatus 12. The collection bag 91 including the used sanitary goods and having the opening portion moves from the solution tank V to the crushing apparatus 12 together with the peroxy acid containing aqueous solution B, and in the crushing apparatus 12, the used bag in the collection bag A is used. Sanitary goods are crushed in the aqueous solution B containing peracid together with the collection bag A.

For example, in the crushing apparatus 12 of FIG. 2, first, the collection bag 91 having the openings and containing the used sanitary goods delivered by the crushing part 60 together with the aqueous solution B containing the peroxy acid from the solution tank V is collected It is crushed in the peracid-containing aqueous solution B together with the bag A (in-liquid crushing step). In the crushing apparatus 12 of FIG. 2, the peracid-containing aqueous solution 92 containing the crushed material obtained in the crushing part 60 (in-liquid crushing step) is drawn from the crushing part 60 by the pump 63 (extraction step) to the next step It is sent out.

The first separation step P13 is performed by the first separation device 13. While stirring the peracid-containing aqueous solution 92 containing the crushed material obtained by the crusher 12 while cleaning to remove dirt from the crushed material, the peracid-containing aqueous solution 92 containing the crushed material is a specified material and a peracid It separates into contained aqueous solution (namely, aqueous solution containing peracid containing pulp fiber and super absorbent polymer) and non-specific material of sanitary goods. At that time, a peracid-containing aqueous solution may be separately added to enhance the washing effect and / or to adjust the pH.

As a result, the peracid-containing aqueous solution 93 from which the foreign matter has been removed is separated from the peracid-containing aqueous solution 92 containing the crushed material through the through holes and delivered from the first separation device 13. On the other hand, in the peracid-containing aqueous solution 92 containing the crushed material, a relatively large nonspecific material can not pass through the through hole, and remains in the first separation device 13 or is delivered by another route. Among the crushed non-specific materials, small ones can not be separated by the first separation device 13 and are included in the aqueous solution containing peracid 93 from which foreign matter has been removed.

Here, when a washing machine is used as the first separation device 13, the size of the through hole of the washing tub functioning as a sieve may be 5 mm to 20 mm in the case of a round hole, and holes of other shapes may be used. In the case, the size of the area substantially the same as that of the round hole may be mentioned.

The first dust removing process P14 is performed by the first dust removing device 14. The peroxy acid-containing aqueous solution 93 from the first separation device 13 from which foreign matter has been removed is passed through a screen, and a peroxy acid-containing aqueous solution containing pulp fibers and a superabsorbent polymer, and crushed non-specific material (foreign body) To separate. As a result, the crushed non-specific material (foreign matter) is separated without passing through the screen, and the peracid-containing aqueous solution 94 from which the foreign matter is further removed is delivered from the first dust removing device 14. On the other hand, the crushed non-specific material (foreign material) can not pass through the screen and remains in the first dust remover 14 or is sent out through another path. Among the crushed non-specific materials, smaller ones are included in the peroxy acid containing aqueous solution 94 from which foreign matter is further removed without being completely separated by the first dust removing device 14.

The second dust removing step P15 is executed by the second dust removing device 15, and the peroxy acid-containing aqueous solution 94 from the first dust removing device 14 from which foreign matter is further removed is passed through a screen, and pulp fibers and superabsorbent polymer are removed. The aqueous solution containing peroxy acid is further separated from the crushed non-specified material (foreign substance). As a result, the crushed non-specific material (foreign material) is separated without being able to pass through the screen, and the peracid-containing aqueous solution 95 from which the foreign material is further removed is delivered from the second dust removing device 15. On the other hand, the crushed non-specific material (foreign matter) can not pass through the screen and remains in the second dust remover 15, or is sent out through another path. Among the crushed non-specific materials, smaller ones are included in the aqueous solution containing peracid 95 from which foreign matter is further removed without being completely separated by the second dust remover 15.

The third dust removal step P16 is performed by the third dust remover 16, and centrifugally separates the peroxy acid-containing aqueous solution 95 from the second dust remover 15, from which foreign matter has been further removed, in the inverted conical housing. A peracid-containing aqueous solution containing pulp fibers and a superabsorbent polymer is further separated from crushed non-specified materials (foreign matter). As a result, the peracid-containing aqueous solution 96 from which foreign matter is further removed is delivered from the upper part of the third dust remover 16 (cyclone separator). On the other hand, crushed non-specific material (foreign material), particularly heavy material such as metal, is delivered from the lower part of the third dust remover 16 (cyclone separator).
The pH of the peroxy acid-containing aqueous solution is adjusted so that the specific gravity and size of the superabsorbent polymer and the specific gravity and size of the pulp fibers are within predetermined ranges.

The decomposition process P17 is performed by the decomposition apparatus 17. The peracid-containing aqueous solution 96 from which the foreign matter is further removed, which is sent from the third dust collector 16, is introduced into the decomposition apparatus 17, and the peracid-containing aqueous solution 96 from which the foreign matter is further removed is heated. And a peracid-derived acid) act as an inactivating agent, while enhancing the oxidizing power by the peracid and further enhancing the function of the peracid as a decomposing agent. By doing so, the superabsorbent polymer adhering to the pulp fibers (for example, remaining on the surface of the pulp fibers) is converted into a low molecular weight organic substance soluble in an aqueous solution and removed from the pulp fibers. Moreover, sterilization, bleaching, deodorization and the like of pulp fibers are performed by the peracid, and a peracid-containing aqueous solution 97 containing recycled pulp fibers is formed.

When the decomposition step P17 is performed, a peracid may be added to the peroxy acid-containing aqueous solution 96 from which foreign matter is further removed. By increasing the total molar concentration of the peracid in the mixed aqueous solution and the peracid-derived acid generated from the peracid, the action of the peracid as a decomposing agent can be enhanced to promote the decomposition of the superabsorbent polymer It is because it can.

The second separation step P18 is executed by the second separation device 18 and processed by the decomposition device 17. The peroxy acid-containing aqueous solution 97 containing recycled pulp fibers passes through the screen having the plurality of slits, and the recycled pulp is removed. The fiber and the aqueous solution containing the peracid are separated. The recycled pulp fibers do not pass through the screen, but remain in the second separation device 18 or are delivered separately.

Hereinafter, the present disclosure will be described by way of examples, but the present disclosure is not limited to these examples.
Example 1
Polyacrylic acid-based highly water-absorbing polymer (Sumitomo Seika Co., Ltd., AquaKeep, unused product) at a temperature ratio of 25 ± 5 ° C. and a humidity of 65 ± 5% RH in a constant temperature and humidity chamber of 150 in mass ratio Immersed in double volume of saline for 10 minutes.
In addition, when the water absorption capacity of the immersed super absorbent polymer was measured according to the method as described in this specification, the absorption capacity was 86.6 (g / g).

Temperature: 25 ± 5 ° C. and humidity: in a constant temperature and humidity room at 65 ± 5% RH, a superabsorbent polymer (manufactured by Sumitomo Seika Chemicals, Aquakeep, unused goods, dry mass: 10 minutes immersed in physiological saline) 1.0 g) 86.6 g of Biocide A, 150 mL of deionized water and 150 mL of deionized water were placed in a beaker and stirred for 10 minutes. The pH was measured with a twin pH meter AS-711 manufactured by Horiba, Ltd. The pH after 1 minute from the start of stirring was 1.8, and the pH after 10 minutes from the start of stirring was 2.2 The
In addition, according to the MDS, Biocide A is composed of 5.6% by mass of peracetic acid, 26.5% by mass of hydrogen peroxide, and 67.9% by mass of acetic acid and water.

It was 8 mass% when the decomposition rate of the highly water-absorbing polymer after stirring for 10 minutes was measured.
In addition, the said decomposition rate was measured as follows.
(1) Put the contents of a beaker in a mesh (NBC Meshtec Co., Ltd., 250 mesh nylon net) and suspend for 5 minutes to remove water adhering to the surface.
(2) The superabsorbent polymer on the mesh is dried at 120 ° C. for 10 minutes, and after the test, the dry mass: m ₃ (g) is measured.
(3) The decomposition rate (mass%) is expressed by the following formula:
Decomposition rate (mass%) = 100 × (1.0-m ₃ ) /1.0
Calculated by

Example 2
The superabsorbent polymer was inactivated and degraded in the same manner as in Example except that the amount of Biocide A was changed to 300 mL.
The pH one minute after the start of stirring was 1.6, and the pH ten minutes after the start of stirring was 1.8. Moreover, the decomposition rate was 72 mass%.
From the above, it can be seen that, by adjusting the treatment time, treatment temperature and the like, peracetic acid can decompose the highly water-absorbent polymer in the sanitary product component.

DESCRIPTION OF SYMBOLS 1 system 11 tearing apparatus 12 shredding apparatus 13 1st separation apparatus 14 1st dust removal apparatus 15 2nd dust removal apparatus 16 3rd dust removal apparatus 17 decomposition apparatus 18 2nd separation apparatus 91 A used hygiene article is included and an opening part is made Collection bag 92 Peroxy acid-containing aqueous solution containing crushed material 93 Peroxy acid-containing aqueous solution from which foreign matter has been removed 94 Peroxy acid-containing aqueous solution from which foreign matter has been removed 95 Peroxy acid-containing aqueous solution from which foreign matter has been further removed 96 Peroxy acid-containing aqueous solution 97 Peroxyacid-containing aqueous solution containing recycled pulp fibers S1 Superabsorbent polymer inactivation and decomposition step S1 _S removal substep S2 recycled pulp fiber recovery step P11 Opening formation process P12 crushing process P13 first separation Process P14 1st dust removal process P15 2nd dust removal process P16 3rd dust removal process P1 Decomposition step P18 the second separation step

Claims

A method of producing recycled pulp fibers from used sanitary goods comprising pulp fibers and superabsorbent polymers, comprising:
The hygienic article constituent material which constitutes the above-mentioned hygiene article which contains the above-mentioned pulp fiber and super absorbent polymer which has an acid group is immersed in the peroxy acid containing aqueous solution containing peroxy acid, and the above-mentioned super absorbent polymer is inactivated. Superabsorbent polymer inactivation and decomposition steps to degrade said superabsorbent polymer together with
A recycling pulp fiber recovery step of recovering the recycling pulp fiber from the peroxy acid-containing aqueous solution subjected to the super absorbent polymer inactivation and decomposition step;
Said method, characterized in that it comprises.
The peracid has the high said smaller acid dissociation constant than acid groups of the water-absorbing polymer (pK a, water) The method of claim 1.
The peracid derived acid formed from the peracid has the superabsorbent said smaller acid dissociation constant than acid groups of the polymer (pK a, water) The method of claim 1 or 2.
The sanitary product construction material is the sanitary product,
The method comprises removing the pulp fiber and the superabsorbent polymer in the sanitary article construction material after immersing the sanitary article construction material in the peroxy acid containing aqueous solution in the superabsorbent polymer inactivation and decomposition step. Further including a removal step for removing
In the superabsorbent polymer inactivation and decomposition step, a peracid is added to the peracid-containing aqueous solution after the removal step.
The method according to any one of claims 1 to 3.
The sanitary product construction material is the sanitary product,
The method comprises removing the pulp fiber and the superabsorbent polymer in the sanitary article construction material after immersing the sanitary article construction material in the peroxy acid containing aqueous solution in the superabsorbent polymer inactivation and decomposition step. Further including a removal step for removing
In the superabsorbent polymer inactivation and decomposition step, the temperature of the aqueous solution containing peracid is increased after the removal step.
A method according to any one of the preceding claims.
The method according to any one of claims 1 to 5, wherein in the recycled pulp fiber recovery step, the recycled pulp fiber is left with a peracid-derived acid generated from the peracid.
Use of peracids for the deactivation and degradation of superabsorbent polymers with acid groups.
An activating and decomposing agent for a superabsorbent polymer having an acid group, which comprises a peracid.