JPH0726486A - Treatment method of pulp - Google Patents

Abstract

PURPOSE:To provide a method for enhancing effect of pulp treatments (bleaching and alkali soaking), using hydrogen peroxide at least. CONSTITUTION:In a pulp treatments by using at least hydrogen peroxide, a treatment method characterized by adding an organic sulfonic acid compound represented by the formula (X)1Ar(SO3)m(M)n, (where X is a group selected from among H, Cl, CH3, C2H5, (CH3)2CH, NH2, OH and COOH, Ar is an aromatic group having an aromatic ring selected from among benzene, naphthalene, naphthoquinone, anthracene and anthraquinone rings, M is H or a metal selected from among alkali metals or alkaline earth metals and l, m and n are each 1 or 2).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for treating pulp. More specifically, the present invention, when bleaching or deinking the pulp with hydrogen peroxide, enhances the treatment effect by adding a specific organic sulfonic acid compound to further increase the whiteness of the pulp. The present invention relates to a possible pulp processing method.

[0002]

2. Description of the Related Art Pulp bleaching has hitherto been carried out mainly by using chlorine bleaching agents in a plurality of stages. However, in recent years, from the viewpoint of protecting the global environment, a bleaching method that does not use chlorine-based bleaching agents as much as possible has been recommended, and a pulp bleaching method that uses oxygen-based bleaching agents such as oxygen and peroxide has been adopted. Among these oxygen-based bleaching agents, hydrogen peroxide is effectively used in the latter stage of the multistage bleaching of chemical pulp, and is mainly used in the bleaching of mechanical pulp. Further, for waste paper pulp disaggregated from waste newspaper and the like, hydrogen peroxide is used to prevent alkaline burning of the pulp by an alkaline chemical added when deinking waste paper pulp. Further, after deinking the printing ink, bleaching is carried out in one or more stages with hydrogen peroxide to obtain a high-whiteness pulp (in this specification,
These chemical pulp, mechanical pulp and waste paper pulp are hereinafter abbreviated as "pulp").

Thus, the treatment with hydrogen peroxide plays an important role in the recent non-chlorine multistage pulp treatment process, but on the other hand, it also has the following problems. That is, a trace amount of impurities such as heavy metals are present in the pulp slurry in which the hydrogen peroxide treatment is performed, and the presence of these impurities promotes the self-decomposition of hydrogen peroxide, which is an originally unstable compound. In other words, the hydrogen peroxide added to the pulp slurry does not 100% effectively act on the bleaching of the pulp, which is the purpose of treatment, and the prevention of alkaline burning, and depending on the state of the system to be treated, the hydrogen peroxide self-decomposes. The result is that the treatment effect is significantly low and the treatment effect is extremely low. This has become an increasingly serious problem due to the increase of impurities in the system accompanying the recent progress of closed water in pulp mills.

[0004]

As described above, the treatment effect of hydrogen peroxide, which is a typical non-chlorine treatment of pulp, is not always satisfactory, and further It was desired to improve. Then, this invention aims at improvement in the hydrogen peroxide treatment of pulp, and an object of this invention is to provide the pulp processing method which the treatment effect improved significantly.

[0005]

[Means for Solving the Problems]

[Summary of the Invention] The present inventors have found that by using a specific organic sulfonic acid compound in combination in a pulp treatment using hydrogen peroxide, hydrogen peroxide acts more effectively and the above object is achieved. It was The present invention is based on such findings. That is, the method for treating pulp according to the present invention comprises treating the pulp with at least hydrogen peroxide, in the formula (X) ₁ Ar (SO ₃ ) _m (M) _n (wherein X is H or Cl, Or CH ₃ , C ₂ H ₅ , (C
H ₃ ) ₂ CH, NH ₂ , OH, and COOH, and Ar represents an aromatic group having an aromatic ring selected from a benzene ring, a naphthalene ring, a naphthoquinone ring, an anthracene ring, and an anthraquinone ring. , M represents H, or a metal selected from alkali metals and alkaline earth metals, and l, m and n are each 1 or 2), and an organic sulfonic acid compound represented by To do.

[Detailed Description of the Invention] <Organic Sulfonic Acid Compound> The organic sulfonic acid compound of the above general formula used in the present invention is used in a cooking method known as hydrotropic cooking in the field of pulp production. Is known. What is hydrotropic cooking? Robert's report (TAPPI 38 (9), 149A (1955))
According to the authors, the hydrotropic phenomenon discovered by Neuberg in 1916 was used to make concentrated aqueous solutions of hydrotropic salts such as benzoate, salicylate, xylene sulfonate and cymene sulfonate insoluble in water. It utilizes the property of dissolving various substances (lignin, etc.). This hydrotropic digest was written by Rybholm,
“Pulping Processes”, Interscience Publishers (19
65), p. 673, 30 of hydrotropic salts
It is a method of cooking with a 50% aqueous solution at 150 to 170 ° C. for 4 to 16 hours. As described above, although the use of the organic sulfonic acid compound used in the present invention in the digestion treatment is known, as far as the present inventors know, in the treatment of pulp with hydrogen peroxide (bleaching treatment, alkaline soaking, etc.) The use of said compound has not yet been reported.

In the method of the present invention, any of the organic sulfonic acid compounds represented by the above general formula is preferably used. Among them, sodium p-toluenesulfonate, sodium benzenesulfonate and sodium m-xylenesulfonate are preferred. Particularly preferably used. According to the invention,
In the treatment of pulp with hydrogen peroxide, the treatment effect is improved by using the above-mentioned specific organic sulfonic acid compound in combination. The reason or mechanism of action has not yet been clarified, but the following consideration is considered possible. That is, the organic sulfonic acid compound acts on the water-insoluble lignin and / or the printing ink on the pulp fiber surface to swell and soften the lignin and the ink, resulting in easy permeation of hydrogen peroxide and alkaline chemicals. Therefore, it is presumed that the bleaching action of hydrogen peroxide or the alkaline burning prevention action is efficiently performed.

<Pulp Treatment According to the Present Invention> The method for treating pulp according to the present invention is characterized by adding the above-mentioned organic sulfonic acid compound when treating the pulp with at least hydrogen peroxide. Here, the “treatment using at least hydrogen peroxide” includes a hydrogen peroxide bleaching treatment for pulp and an alkali dipping treatment for pulp (usually called alkali soaking). In alkaline soaking of pulp, hydrogen peroxide is used together with an alkaline agent such as caustic soda to prevent alkaline burning of the pulp. The hydrogen peroxide bleaching treatment of the pulp is generally carried out at a pulp concentration of 1 to 35% by weight, preferably 5 to 20% by weight, and the amount of hydrogen peroxide used is 0.5 to 10% by weight based on the absolutely dried pulp. , Preferably 1 to 5% by weight.
Alkali immersion treatment of pulp generally has a pulp concentration of 5 to 3.
5% by weight, preferably 10 to 30% by weight, caustic soda 0.5 to 5% by weight, preferably 1 to 3% by weight, sodium silicate (JIS 3) 1 to 8% by weight, preferably 2 to 6%
% By weight, 0.5 to 5% by weight of hydrogen peroxide, preferably 1 to
3% by weight, a surfactant of 0.01 to 3% by weight, preferably 0.05 to 1% by weight, etc. are used (all chemicals used are absolute dry pulp).

The organic sulfonic acid compound used in the present invention is generally 0.01 to 4% by weight, preferably 0.01 to 0.5, based on the absolutely dry pulp in any of the above treatments.
Used in an amount of% by weight. The treatment conditions for adding the organic sulfonic acid compound are pulp slurry pH 5 to 12 and treatment temperature 40 to 95 in any of the above treatments.
C., the treatment time is preferably 5 minutes to 24 hours. The pulp which is the object of the present invention includes ground wood pulp (GP), refiner mechanical pulp (RMP), thermomechanical pulp (TMP), chemiground pulp (CGP), semi-chemical pulp (SCP), sulfite pulp (S).
P), kraft pulp (KP), alkaline pulp (A
P), waste paper pulp, and deinked pulp of waste paper (DIP)
Etc., and both wood pulp and non-wood pulp are covered.

[0010]

EXAMPLES Examples of the present invention will be shown below and described in more detail, but these examples do not limit the present invention in any way. The amount of reagent used in the examples (%)
All represent% by weight based on the weight of the absolutely dried pulp. Examples 1 to 12 and Comparative Example 1 Waste magazine paper was disaggregated with a test pulper at a concentration of 5% for 5 minutes. With respect to this disintegrated pulp, an organic sulfonic acid compound of the type shown in Table 1 was used in an amount shown in the same table, and an alkali dipping treatment was carried out under the following conditions. A comparative experiment was also conducted in which the organic sulfonic acid compound was not added (Comparative Example 1). <Processing conditions> Pulp concentration: 17% Hydrogen peroxide usage: 3.5% Caustic soda usage: 2% Sodium silicate (JIS No. 3) usage: 5% Surfactant ^* usage: 0.2% Organic sulfonic acid Amount of compound used: 0 to 0.5% Treatment temperature: 60 ° C. Treatment time: 3 hours *: FT301A manufactured by Toho Chemical Industry Co., Ltd. Whiteness of the pulp after the above treatment was measured according to ISO2469. The results obtained are shown in Table 1.

Table 1 _{Example No.} ^{Organic sulfonic acid compound} pulp ^{species Usage (%) Whiteness (%)} Example 1 p-toluenesulfonic acid Na 0.01 65.5 〃 2 〃 0.03 67.1 〃 3 〃 0.05 67.6 〃 4 〃 0.10 66.8 〃 5 〃 0.30 67.0 〃 6 〃 0.50 67.1 〃 7 Na benzenesulfonate 0.1 66.5 〃 8 Benzene-m-disulfonic acid Na 0.1 65.9 〃 9 m-xylene-4-sulfonic acid Na 0.1 66.3 〃 10 p-xylene-4-sulfonic acid Na 0.1 65.9 〃 11 p -Toluidine-m-sulfonic acid 0.1 65.9 〃 12 Anthraquinone-β-sulfonic acid Na 0.1 66.1 Comparative Example 1--64.8

[0012]

INDUSTRIAL APPLICABILITY By using a specific organic sulfonic acid compound in combination in the pulp treatment using hydrogen peroxide (bleaching treatment, alkali dipping treatment) according to the method of the present invention, the treatment effect by hydrogen peroxide is increased and the peroxide It is possible to obtain a high-whiteness pulp that cannot be obtained by the hydrogen treatment alone.

Claims (4)

[Claims] 1. When treating pulp with at least hydrogen peroxide, the general formula (X) ₁ Ar (SO ₃ ) _m (M) is used.
_n (wherein, X is H or Cl, or CH ₃ , C
₂ H ₅ , (CH ₃ ) ₂ CH, NH ₂ , OH and COO
Represents a group selected from H, Ar represents an aromatic group having an aromatic ring selected from a benzene ring, a naphthalene ring, a naphthoquinone ring, an anthracene ring and an anthraquinone ring, and M represents H, or an alkali metal and an alkaline earth Represents a metal selected from the group of metals, where l, m and n are each 1
Or 2), a method for treating pulp, comprising adding an organic sulfonic acid compound represented by the formula (2). 2. The method according to claim 1, wherein the organic sulfonic acid compound is sodium p-toluenesulfonate, sodium benzenesulfonate or sodium m-xylenesulfonate. 3. The amount of the organic sulfonic acid compound added is 0.01 to 4% by weight based on absolute dry pulp.
The method described in. 4. The pulp slurry pH during the treatment for adding the organic sulfonic acid compound is 4 to 12, and the treatment temperature is 40 to 95.
The method according to any one of claims 1 to 3, wherein the treatment temperature is 5 minutes to 24 hours.