JP3405888B2 - Deinking method - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to newspapers, leaflets,
The present invention relates to a deinking method for deinking and reusing used paper such as magazines. More specifically, the present invention relates to a deinking method for obtaining a deinked pulp having excellent opacity, while maintaining an appropriate whiteness and yield.

[0002]

2. Description of the Related Art In recent years, the characteristics of waste paper used as a raw material have been diversified due to the increasing demand for beautiful and stable printing and the progress of printing technology. In addition, the degree of binding of ink to paper is wide ranging from mild to strong. Under such circumstances, it is required to improve the quality and yield (that is, productivity) of deinked pulp. In order to achieve this object, various proposals have been made in various fields including a deinking process, a deinking agent, and a device used for deinking.

For example, a surfactant such as polyoxyethylene alkyl ether or a fatty acid salt is generally used for the purpose of peeling ink from waste paper or for generating bubbles for adhering the peeled ink. Deinking agents are used in any of the above steps, and there are many inventions relating to the optimization of the structure thereof (JP-A-4-308290, JP-A-4-327279, JP-A-7-3681 and JP-A-7-3681). -324292, etc.). Also, very few are known to use cationic compounds, amines, acid salts of amines, and amphoteric compounds (JP-A-59-53532, US Pat. No. 40).
43908, JP-A-4-202879, JP-A-6-192986
issue).

[0004]

However, with these methods, it is not possible to obtain high opacity while maintaining moderate whiteness and yield as a whole. The reason is that polyoxyethylene alkyl ether and fatty acid salts have excellent ink peeling ability and also have excellent fine fiber dispersing ability, so that they are removed during flotation and whiteness is improved. , Yield and opacity decrease. Further, those using a cationic compound, an amine, an acid salt of an amine and an amphoteric compound have poor ink stripping ability and also poor ink removal efficiency during flotation, so that a sufficient deinking effect cannot be achieved. Thus, in the conventional method of peeling and flotation of the ink using the same surfactant, the deinked pulp with sufficient opacity that plays an important role in the printing characteristics of the paper, a suitable whiteness, It was difficult to obtain while maintaining the yield.

[0005]

In view of the above situation, the present inventors have conducted earnest research from the viewpoint of a deinking method, and as a result, used a nonionic surfactant as a deinking agent to produce waste paper. The ink is sufficiently peeled off, and the flotation step is carried out in the presence of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound in a pH range of more than 9 to 12 or less, thereby improving printability. Found that deinked pulp having excellent opacity of the deinked pulp sheet can be obtained while maintaining appropriate whiteness and yield, and completed the present invention. The opacity of the pulp sheet is an important performance in order to prevent back ink loss during printing, and increasing the opacity enables a more beautiful finish.

[0006] That is, the present invention is a deinking method comprising at least a step of peeling ink from raw waste paper and a step of removing the peeled ink from the flotation system. At least one nonionic surfactant, and at least part of the flotation step in the presence of at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds; PH in the range of super to 12 or less
Provides a way to do it.

In the present invention, at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is used in the system for flotation.
It is preferable to add it after adjusting the pH of the system to a value within the range of more than 9 to 12 or less. In this case, at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound is an amount such that the pH of the system for flotation hardly changes by the addition of these compounds. Are preferably used in. Further, in the present invention, at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is used in an amount of 0.001 to 5.0 based on the weight of waste paper.
It is preferred to add in the amount of wt%.

In the present invention, when at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound contains a cationic compound alone or contains a cationic compound, a nonionic surfactant. Is preferably used in an amount of 0.25 to 5.0% by weight, based on the weight of the waste paper.

Further, in the present invention, the nonionic surfactant is preferably selected from the group consisting of the following nonionic surfactants (A) to (D). Nonionic Surfactant (A): Reaction Product Obtained by Adding Alkylene Oxide to Mixture of Oil and Fat Nonionic Surfactant (B): Formula: RCOO (AO) _m R ′
(Wherein R represents an alkyl or alkenyl group having 7 to 23 carbon atoms, and R'is a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, an alkenyl group having 2 to 22 carbon atoms, or Represents an acyl group having 2 to 22 carbon atoms, AO is
An oxyalkylene group having 2 to 4 carbon atoms is shown, and m is an integer of 1 or more. ) Nonionic surfactant (C): compound represented by the formula: RO (AO) _n H (wherein R represents an alkyl or alkenyl group having 8 to 24 carbon atoms, and AO is 2 to 2 carbon atoms). 4 represents an oxyalkylene group, and n is an integer of 1 or more.) Nonionic surfactant (D): reaction product obtained by adding alkylene oxide to polyvalent carboxylic acid or its acid anhydride, Alternatively, a reaction product obtained by adding alkylene oxide to a mixture of a polycarboxylic acid or an acid anhydride thereof and an alcohol, in the alkylene oxide adduct in the nonionic surfactant, the addition form of alkylene oxide is , Block, random, or a mixture thereof.

Examples of the cationic compound, amine, acid salt of amine and amphoteric compound used in the present invention include the following.

<Cationic Compound> The cationic compound includes compounds represented by the following formulas (a ₁ ) to (e ₁ ) and the following formulas:
(f ₁ ) to (j ₁ ) and has a cationic nitrogen content of 0.01
~ 35% by weight, and a weight average molecular weight of 2,000 to 3,
It is preferably selected from the group consisting of cationic polymers which are, 000,000.

[0012]

[Chemical 8]

In the formulas (a ₁ ) to (e ₁ ), R ₁ and R
₂ are the same or different from each other and each have 1 carbon atom
Is an alkyl, alkenyl or β-hydroxyalkyl group having 0 to 24, R ₃ , R ₄ and R ₅ are the same or different from each other and are respectively an alkyl or hydroxyalkyl group having 1 to 8 carbon atoms, a benzyl group, Or expression:-
A group represented by (AO) _n -Z (where AO is an oxyalkylene group having 2 to 4 carbon atoms, Z is a hydrogen atom or an acyl group, and n is an integer of 1 to 50). And
R ₆ is alkyl having 8 to 36 carbon atoms, alkenyl or β
Is a hydroxyalkyl group, X ⁻ is a counter ion, Y is an alkyl, alkenyl or β-hydroxyalkyl group having 8 to 36 carbon atoms, and has the formula: R ₆ COOCH ₂ — (wherein R ₆ is as defined above. The group represented by
A group represented by the formula: R ₆ CONHCH ₂ — (wherein R ₆ is as defined above) or a formula: R ₆ OCH ₂ — (wherein R ₆ is as defined above) Is a group that is

[0014]

[Chemical 9]

In the formulas (f ₁ ) to (j ₁ ), R ₁ ,
_{R 2, R 3, R 6} , R 7, R 8 and R ₉ are the same or different from each other, respectively, an alkyl group or an alkenyl group having a carbon number of 2 to 24 1 to 24 carbon atoms, R ₄ And R ₅ are the same or different from each other, respectively, a hydrogen atom or a methyl group, X ⁻ and W ⁻ are the same or different from each other, respectively, a counterion, and Y and Z
Are the same or different from each other, respectively, O or NH
And AO is an oxyalkylene group having 2 to 4 carbon atoms, p and q are the same or different from each other, and each is an integer of 1 to 10, and r is an integer of 0 to 10. , L, m and n are positive numbers such that the weight average molecular weight of the polymer is a value within the range of 2,000 to 3,000,000.

<Amine, acid salt of amine> The amine and acid salt of amine are represented by the compounds represented by the following formulas (a ₂ ) to (h ₂ ) and the following formulas (i ₂ ) to (l ₂ ), Amino nitrogen content is 0.0
1 to 35% by weight and weight average molecular weight of 2,000 to
It is preferably selected from the group consisting of polymers which are 3,000,000.

[0017]

[Chemical 10]

In the formulas (a ₂ ) to (h ₂ ), R ₁ is an alkyl, alkenyl or β-hydroxyalkyl group having 8 to 36 carbon atoms, R ₂ and R ₃ are the same or different from each other. And a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, respectively, H
A represents an inorganic or organic acid, AO is an oxyalkylene group having 2 to 4 carbon atoms, and l and m are respectively 1
+ M is an integer of 1 to 300, and is 0 or a positive integer, and W ₁ , W ₂ , W ₃ and W ₄ are the same or different from each other and each represent a hydrogen atom or a carbon number of 1 to
24 alkyl groups.

[0019]

[Chemical 11]

In formulas (i ₂ ) to (l ₂ ), R ₁ is an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, and R ₂ , R ₃ and R ₆ are the same as each other. The same or different, each is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, and R ₄
And R ₅ are the same or different from each other, respectively, a hydrogen atom or a methyl group, HA is an inorganic or organic acid, Y is O or NH, p is an integer of 1 to 10. Yes, l, m and n are positive numbers such that the weight average molecular weight of the polymer is a value within the range of 2,000 to 3,000,000.

<Amphoteric compound> The amphoteric compound is represented by the following formula (a
Compounds represented by ₃₎ ~ (j _3), phospholipids (k _3), proteins
(l ₃ ) and a group consisting of amphoteric polymers represented by the following formulas (m ₃ ) and (n ₃ ) having a cationic nitrogen content of 0.01 to 35% by weight and a weight average molecular weight of 2,000 to 3,000,000. It is preferably selected from

[0022]

[Chemical 12]

In the formulas (a ₃ ) to (j ₃ ), R ₁ , R ₂
And R ₃ are the same or different from each other and are an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, respectively, and R ₄ is an alkyl group having 8 to 36 carbon atoms, alkenyl or β-. Is a hydroxyalkyl group, M is
A hydrogen atom, an alkali metal atom, 1/2 mol of an alkaline earth metal atom or an ammonium group, and Y ₁ is represented by the formula: R ₅
NHCH ₂ CH ₂ — (wherein R ₅ is an alkyl group having 1 to 36 carbon atoms, or an alkenyl or hydroxyalkyl group having 2 to 36 carbon atoms),
Y ₂ is a hydrogen atom or a group represented by the formula: R ₅ NHCH ₂ CH ₂ — (wherein R ₅ is as defined above), and Z ₁ is —CH ₂ COOM (here, M is as defined above), Z ₂ is a hydrogen atom or a group represented by the formula: —CH ₂ COOM (where M is as defined above). .

[0024]

[Chemical 13]

In the formulas (m ₃ ) and (n ₃ ), R ₁ , R ₂
And R ₃ are the same or different from each other, and each represent a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or 2 to 2 carbon atoms.
4 is an alkenyl group, R ₄ and R ₅ are the same or different from each other and each is a hydrogen atom or a methyl group, and M is a hydrogen atom, an alkali metal atom, or 1/2 mol of an alkaline earth metal. an atom or an ammonium group, X ^-
Is a counterion, Y is O or NH, p is 1
It is an integer of 10 and m and n are positive numbers such that the weight average molecular weight of the polymer is a value within the range of 2,000 to 3,000,000.

Further, in the present invention, it is preferable to maintain the flotation type calcium ion concentration at a concentration of 10 to 400 ppm. Furthermore, it is preferable to maintain the flotation type aluminum ion concentration at a concentration of 0 to 40 ppm.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION In a flotation step as one of the deinking steps, a pulp / water slurry is foamed by an appropriate means such as a physical means or a chemical means, and ink droplets are attached to floating bubbles. Then, by discharging, the ink is separated from the pulp, but in the deinking method of the present invention, at least a part of this flotation step, preferably more flotation steps, especially all The flotation step is more than 9 and less than 12, preferably 9
It may be carried out at a pH within the range of super to 11 or less. Therefore, the pH of the pulp / water slurry may be adjusted in any step before the flotation, but it is preferably performed immediately before the flotation.

The steps before flotation are generally carried out at basic pH. Therefore, in the present invention, a suitable acid or an aqueous solution of an acid may be added to the pulp / water slurry before or during the flotation to adjust the pH of the slurry to a value within the above range. The method of adding the acid is not particularly limited, and for example, an acid or an aqueous solution of the acid may be added to water injected into the slurry before or during the flotation. Examples of acids used to adjust the pH of the slurry include inorganic acids such as hydrochloric acid, sulfuric acid and nitric acid, and organic acids such as acetic acid, formic acid and citric acid. The method of adjusting the pH of the slurry is not limited to using an acid. Needless to say, when the pH becomes too low, it may be adjusted with alkali such as NaOH.

In the present invention, the pulp / water slurry must contain at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds in at least one step of flotation. Therefore, at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine, and an amphoteric compound, unless the step is performed after flotation,
It may be added at any step of the deinking method. that is,
It may be added in one step before the flotation, for example, the disaggregation step or the bleaching step, or may be added immediately before the flotation or during the flotation (for example, the initial stage of the flotation step). It is preferable to add at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound, immediately before or during the flotation, and particularly, the pH of the slurry is more than 9 to 12. It is advisable to add it to the slurry after adjusting it to a value within the following range. In this case, at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound is used in an amount such that the pH of the system for flotation hardly changes by its addition. Good. "The pH of the system for flotation hardly changes" means that the pH change of the system is ± 0.1 or less in pH measurement. The amount of the cationic compound, the amine, the acid salt of the amine and the amphoteric compound, "the pH of the system for flotation is hardly changed" by the addition thereof depends on the structure of the compound, but is, for example, the weight of waste paper (ie, , The absolute dry weight of waste paper) is 0.01 to 1.0% by weight.

Further, for example, when the flotation system is circulated, the flotation step may consist of two or more steps. In such cases, the pH of the system is above 9 to 12 in at least one flotation step.
It must be adjusted to a value within the following range. PH of system
Is preferably adjusted as described above during the plurality of steps of flotation, particularly in the step immediately before the washing step. At least one selected from the group consisting of a cationic compound, an amine, an amine acid salt and an amphoteric compound must also be present in a system having a pH of more than 9 and 12 or less in at least one step of flotation.

In the present invention, at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is used in flotation based on the weight of waste paper (that is, the absolute dry weight of waste paper). , 0.00
1 to 5.0% by weight, preferably 0.01 to 1.0% by weight
Used in an amount of. When at least one selected above is present in the system during flotation, that is, in the slurry, in the above amount, the ink is efficiently removed from the system while leaving fine fibers in the slurry. be able to.

In the present invention, if at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is a cationic compound or contains a cationic compound, deinking is carried out. The nonionic surfactant that is an agent is based on the weight of waste paper,
It is preferably used in an amount of 0.25 to 5.0% by weight. The whiteness is also improved in this range.

Next, the nonionic surfactant used as the deinking agent in the present invention will be explained. In the present invention, as the deinking agent, it is preferable to use one kind or two or more kinds selected from the group consisting of the following nonionic surfactants (A) to (D). <Nonionic Surfactant (A): Reaction Product Obtained by Adding Alkylene Oxide to Mixture of Fats and Oils>Alcohol> Nonionic surfactant (A) is a mixture of fats and oils and monohydric or polyhydric alcohols. It is an alkylene oxide adduct of a mixture. The alkylene oxide is added to the above mixture in an amount of 5 to 300 mol on average, preferably 20 to 150 mol, per 1 mol of the mixture. Examples of alkylene oxide include ethylene oxide, propylene oxide and butylene oxide, which may be used alone or in the form of a mixture of two or more thereof.

The mixing ratio of fats and oils to alcohol is 1
/0.1 to 1/6 is preferable, and 1 / 0.3 to 1/3 is particularly preferable. When the ratio is within the above range, the ink is sufficiently peeled off, and a regenerated pulp having a good appearance is obtained.

Examples of oils and fats as a raw material of the nonionic surfactant (A) include palm oil, palm oil, olive oil, soybean oil, rapeseed oil, vegetable oil such as linseed oil, animal oils such as lard, beef tallow and bone oil. , Fish oils, hydrogenated and semi-hardened oils thereof, and recovered oils obtained in the refining process of these fats and oils. Palm oil, palm oil and beef tallow are particularly preferable.

Examples of the monohydric alcohol as a raw material for the nonionic surfactant (A) include those having an alkyl or alkenyl moiety having 8 to 24 carbon atoms, and the alkyl moiety having 6 to 14 carbon atoms. Those having an alkylphenyl moiety can be mentioned. Preferably 12 to 18 carbon atoms
Having an alkyl moiety of.

Examples of the polyhydric alcohol as a raw material of the nonionic surfactant (A) include ethylene glycol, propylene glycol, glycerin, trimethylolpropane and the like.

<Nonionic surfactant (B): Formula: RCO
Compound Represented by O (AO) _m R ′> In the above formula, R represents an alkyl or alkenyl group having 7 to 23 carbon atoms, and R ′
Is a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, or 2 carbon atoms
~ 22 alkenyl group or C2-22 acyl group, preferably hydrogen, AO represents a C2-4 oxyalkylene group, and m is an integer of 1 or more. A
The average added mole number of O is preferably 5 to 300 moles. Further, it is preferable to use ethylene oxide and propylene oxide as AO in a molar ratio of ethylene oxide to propylene oxide of 1/5 to 5/1.
Among the nonionic surfactants (B), those in which the carbon number of the alkyl or alkenyl group represented by R, particularly the carbon number of the alkyl group is 11 to 23 are preferable.

<Nonionic surfactant (C): Formula: RO
Compound Represented by (AO) _n H> In the above formula, R represents an alkyl or alkenyl group having 8 to 24 carbon atoms, and AO is
An oxyalkylene group having 2 to 4 carbon atoms is shown, and n is an integer of 1 or more. The average addition mole number of AO is preferably 5 to 300 moles, and more preferably 7 to 150 moles. Further, it is preferable to use ethylene oxide and propylene oxide as AO in a molar ratio of ethylene oxide to propylene oxide of 1/5 to 5/1.

Examples of monohydric alcohols used for producing the nonionic surfactant (C) include 8 to 8 carbon atoms.
Examples thereof include those having 24 alkyl or alkenyl moieties and those having an alkylphenyl moiety in which the alkyl moiety has 6 to 14 carbon atoms. Specific examples thereof include those described for the nonionic surfactant (A). Among the nonionic surfactants (C),
The alkyl or alkenyl group represented by R has 14 carbon atoms.
-24 are preferable.

<Nonionic surfactant (D): Reaction product obtained by adding alkylene oxide to polyvalent carboxylic acid or acid anhydride thereof, or polyvalent carboxylic acid or acid anhydride thereof and alcohol The reaction product obtained by adding alkylene oxide to the mixture with the> nonionic surfactant (D) is produced by using a polycarboxylic acid or its acid anhydride (I) and an alcohol (II). It At that time, the compounds (I) and (II) are the same as (I) with respect to (II).
The molar ratio of 1 / 0.02 to 5, especially 1 / 0.1 to 3, is preferably used. The polyvalent carboxylic acid as a raw material of the nonionic surfactant (D) has 14 to 22 carbon atoms.
The higher fatty acid dimer acid and polymer acid of are preferred,
Dimer acid is particularly preferable.

The nonionic surfactant may be added at any step of the deinking method. However, addition in the pulping step is usually preferred. The amount added is not particularly limited, but is preferably 0.01 to 10% by weight, particularly 0.01 to 5% by weight, and further preferably 0.25 to 5% by weight, based on the used waste paper. A sufficient deinking effect cannot be achieved only by the deinking agent other than these nonionic surfactants of the present invention.
Further, known deinking agents other than the above nonionic surfactants (A) to (D) can be used in combination therewith.

The deinking method of the present invention is also characterized in that at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is present in the system during flotation.

Examples of the cationic compound used in the present invention include mono-long-chain alkyl type quaternary ammonium salts, di-long-chain alkyl type quaternary ammonium salts, pyridinium salts having a substituent at the nitrogen atom, And cationic polymers. In particular, the represented by formula (a ₁₎ ~ compounds and the formula represented by _{(e 1) (f 1)} ~ (j 1), a cationic nitrogen content is 0.01 to 35 wt%, and the weight Cationic polymers having an average molecular weight of 2,000 to 3,000,000 are preferred. Particularly preferably, the following formulas (a ₁ ), (b ₁ ),
a cationic compound represented by (d ₁ ) and the following formula (i ₁ )
It is a cationic polymer represented by.

[0045]

[Chemical 14]

[In the formulas (a ₁ ), (b ₁ ) and (d ₁ ),
R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ and X ⁻ are the same as above. Further, in the formula (i ₁ ), R ₁ , R ₂ , R ₃ ,
X ⁻ , AO, r and l are the same as above. Above all, in the formula (b ₁ ), R ₃ , R ₄ , and R ₅ are particularly preferable.
Compound but R ₆ an alkyl group having 1 to 3 carbon atoms is an alkyl group having 8 to 20 carbon atoms, the formula (d ₁₎ at R ₃ the number R ₆ carbon alkyl group having 1 to 3 carbon atoms 8 Since a compound which is an alkyl group of ~ 20 can obtain high opacity,
preferable.

Examples of amines or acid salts of amines used in the present invention include primary amines, secondary amines, tertiary amines, cyclic amines, imidazoles and imidazolines, inorganic acid salts of these amines, and these amines. Mention may be made of organic acid salts and polymers containing amino groups. In particular, the above formula
Compounds represented by (a ₂ ) to (h ₂ ) and the formula (i ₂ ) to
Preferred is a polymer represented by (l ₂ ), which has an amino nitrogen content of 0.01 to 35% by weight and a weight average molecular weight of 2,000 to 3,000,000. Among them, the following formula (a ₂ ),
The amines represented by (b ₂ ), (e ₂ ), and (f ₂ ) or acid salts thereof, and the amino group-containing polymers represented by the following formula (l ₂ ) are more preferable.

[0048]

[Chemical 15]

[In the formulas (a ₂ ), (b ₂ ), (e ₂ ) and (f ₂ ), R ₁ , R ₂ , R ₃ and HA are the same as defined above. Further, in the formula (l ₂ ), HA and l are the same as above. Above all, in the formulas (a ₂ ) and (b ₂ ), a compound in which R ₁ is an alkyl group having 8 to 12 carbon atoms and R ₂ and R ₃ are both hydrogen has high opacity. ,preferable.

Examples of the amphoteric compound used in the present invention include betaine, amine oxide, phospholipid, protein and amphoteric polymer. In particular, the formula (a ₃ ) to
a compound represented by (j ₃ ), a phospholipid (k ₃ ), a protein
An amphoteric polymer represented by the formula (l ₃ ) and the following formulas (m ₃ ) and (n ₃ ) and having a cationic nitrogen content of 0.01 to 35% by weight and a weight average molecular weight of 2,000 to 3,000,000 is preferable. Particularly preferably, the formulas (a ₃ ), (b ₃ ), (c ₃ ),
An amphoteric compound represented by (d ₃ ), (g ₃ ), or (h ₃ ) and an amphoteric polymer represented by the following formula (m ₃ ).

[0051]

[Chemical 16]

[Formulas (a ₃ ), (b ₃ ), (c ₃ ), (d ₃ ),
In (g ₃ ) and (h ₃ ), R ₁ , R ₂ , R ₃ , R ₄ ,
M, Y ₁ and Y ₂ are the same as above. Further, in the formula (m ₃ ), R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , M, X ⁻ , Y,
p, m and n are the same as above. ].

Among the above, in the formulas (a ₃ ) and (b ₃ ), R ₁ is an alkyl group having 8 to 12 carbon atoms, R ₂ and R ₃
Is a compound having 1 to 3 carbon atoms, and a compound of the formula (g
_{In 3} ), a compound in which R ₄ is an alkyl group having 8 to 20 carbon atoms, particularly 8 to 12 carbon atoms is preferable because high opacity can be obtained.

Among the above-mentioned cationic compounds, amines, acid salts of amines and amphoteric compounds, it is preferable to use amines or acid salts of amines because high opacity can be obtained, and among them, the above formulas (a ₂ ) and (a) The amine represented by b ₂ ) and the acid salt of amine are more preferable. In particular, as mentioned above, the formula
In (a ₂ ), (b ₂ ), a compound in which R ₁ is an alkyl group having 8 to 12 carbon atoms and R ₂ and R ₃ are both hydrogen is most preferable.

In the deinking method of the present invention, the calcium ion concentration of the system at the time of flotation, that is, the slurry, is
It is not particularly limited. However, in order to obtain higher quality recycled pulp, the calcium ion concentration of the system at the time of flotation is 10 to 400 ppm, particularly 100 to 25 ppm.
It is preferable to adjust the value within the range of 0 ppm. When the calcium ion concentration is within the above range, the fine cellulose is adsorbed on the larger cellulose, the redeposition of the ink is also suppressed, and the outflow of the fine cellulose to the outside of the system during the flotation is reduced, so that the opacity is improved. can get.

Inorganic calcium salts such as calcium chloride and calcium carbonate and minerals such as lime can be used for controlling the calcium ion concentration of the system. Furthermore, animal bones, shells and the like may be used as the calcium ion source. In that case, animal bones are reacted with acid,
Ionized. The calcium ion concentration of the system in flotation is preferably adjusted to a value within the above range, but the calcium ion concentration of the system in any step other than the flotation step is not particularly limited. Therefore, the calcium ion concentration of the system may be adjusted in any step (pulping step or the like) before the flotation step as long as it does not affect the ink peeling.

In the deinking method of the present invention, the aluminum ion concentration in the flotation system is preferably 40.
It is adjusted to below ppm, especially below 25 ppm. In order to adjust the aluminum ion concentration of the system, it is preferable to consider the type and amount of water used in flotation. For example, white water and / or tap water generated during papermaking is used in an appropriate amount. When the aluminum ion concentration of the system in flotation is adjusted as described above, it contributes to the improvement of opacity together with other factors. The aluminum ion concentration of the system in flotation is preferably adjusted to a value within the above range, but the aluminum ion concentration of the system in any step other than the flotation step is not particularly limited. Therefore, the aluminum ion concentration of the system may be adjusted in any step (such as a pulping step) before the flotation step as long as it does not affect the ink peeling.

In the above-described deinking method of the present invention, at least one of the nonionic surfactants (A) to (D) is used, and at least part of the flotation step is performed by using a cationic compound, an amine, A step of peeling the ink from the waste paper, characterized in that it is carried out in the presence of at least one kind selected from the group consisting of an acid salt of an amine and an amphoteric compound, at a pH within the range of more than 9 to 12 or less. , The step of removing the ink separated from the flotation system. Other steps can be performed according to the conventional deinking method. That is, in general, the deinking method has the following major steps: (1) waste paper pulping (disaggregation) step, (2)
Aging, that is, the step of leaving the disintegrated paper as it is,
Includes (3) flotation step and (4) washing step. If necessary, other steps may be included, and each step may be performed twice or more.

The mechanism by which the deinking method of the present invention exhibits such an excellent deinking effect is not necessarily clear, but is considered as follows. That is, by using a nonionic surfactant as the deinking agent, the ink is sufficiently peeled from the pulp. Furthermore, the pH of the system before or during flotation is adjusted to more than 9 to 12 or less,
The presence of at least one selected from the group consisting of a cationic compound, an amine, an amine acid salt and an amphoteric compound allows the cationic compound, the amine and the amine acid salt, and the amphoteric compound to be selectively present at the interface of the ink and pulp. The ink and pulp aggregate to a suitable size by adsorbing onto At this time, since the deinking agent which has been peeled off, that is, the nonionic surfactant covers the surface of the pulp, the re-adhesion of the once peeled ink to the pulp is prevented. In the conventional deinking method, the fibers finely divided by the mechanical force at the time of ink removal are dispersed by the surfactant that is the deinking agent,
When bubbles were blown in this state, the fine fibers were discharged out of the system together with the ink and the like. However, in the present invention, the coexistence of the cationic compound, the amine, the acid salt of the amine, and the amphoteric compound causes the fine fibers that have been conventionally discharged to agglomerate and adsorb onto the larger pulp fibers, whereby the fine fibers stay in the system. As a result, the opacity of the sheet is improved by embedding the fine fibers in the fiber gaps in the recycled sheet made from the deinked pulp. Such improvement of opacity greatly contributes to prevention of strike-through of ink during printing, and improvement of printability is achieved. More preferably, by allowing calcium ions and aluminum ions to be present in the flotation system in an appropriate amount, adsorption of cationic compounds, amines and acid salts of amines, and amphoteric compounds to fine pulp fibers and its subsequent aggregating action are further improved. It can be demonstrated selectively and strongly. Although the detailed mechanism is unknown, calcium ion and aluminum ion are a hydroxyl group of cellulose, a cationic compound, an amine and an acid salt of amine,
It is considered that this contributes to more strongly adsorbing the hydrophilic part of the amphoteric compound.

In any case, in the deinking method of the present invention, (1) the nonionic surfactant is used as the deinking agent, and (2) the pH of the system in the presence of the above nonionic surfactant. To the stated range, and (3)
It is essential to carry out the flotation step in the presence of at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds.

[0061]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

The following Tables 1 to 16 show the cationic compounds (Tables 1 to 4), amines used in the following Examples and Comparative Examples.
Amine acid salts (Tables 5-9) and amphoteric compounds (Tables 10-1)
6) is shown. In addition, in each table, each numerical value in the column of R ₁ ... R _n means the carbon number of the linear alkyl group as a substituent. Further, the cationic nitrogen or amino nitrogen content (%) of the polymer is determined by the molecular formula of the polymer to the nitrogen content (%) measured by the Kjeldahl method. It is calculated by multiplying the ratio.

[0063]

[Table 1]

[0064]

[Table 2]

[0065]

[Table 3]

[0066]

[Table 4]

[0067]

[Table 5]

[0068]

[Table 6]

[0069]

[Table 7]

[0070]

[Table 8]

[0071]

[Table 9]

[0072]

[Table 10]

[0073]

[Table 11]

[0074]

[Table 12]

[0075]

[Table 13]

[0076]

[Table 14]

[0077]

[Table 15]

[0078]

[Table 16]

Further, in the following examples, "EO" and "PO" respectively represent an oxyethylene group and an oxypropylene group, and the subscript number represents the average number of moles of ethylene oxide or propylene oxide added.

Examples 1 to 41 and Comparative Examples 1 to 4 Raw material waste paper (newspaper / flyer = 70/3) recovered in the city
0) is shredded into 4 cm x 4 cm pieces, and a certain amount is put into a table disintegrator, and hot water and sodium hydroxide 1% by weight (relative to raw material), sodium silicate 3% by weight (relative to raw material), 30% peroxide 3% by weight of hydrogen water (to the raw material) and 0.5% by weight of stearyl alcohol EO ₂₀ PO ₂₀ block adduct (to the raw material) as a deinking agent were added, and disintegrated at 40 ° C. for 10 minutes at a pulp concentration of 5% by weight. The obtained pulp slurry was aged at 40 ° C. for 60 minutes, then warm water was added to dilute the pulp concentration to 1%, and sodium hydroxide and sulfuric acid were used to give the results shown in Tables 17 to 19.
The pH and Ca and Al ions were adjusted as shown in FIG. The pH was adjusted to be constant throughout the flotation process (the same applies to the examples below). Further Tables 17-1
The additive compound shown in 9 was added, and a flotation treatment was performed at 40 ° C. for 10 minutes. Here, the concentration of the added compound is% by weight based on the raw waste paper (the same applies to the following examples). After the flotation treatment, a pulp sheet was prepared with a tapping machine, pressed at 5 kgf / cm ² and then air-dried,
The opacity of the pulp sheet was measured.

The opacity of this embodiment is 60 g as basis weight.
After making a sheet with / m ³ , JI using a color machine
Obtained by the method of SP 8138. In addition, the difference of 1% opacity is that the transparency can be visually recognized sufficiently, and when printing is further performed, the difference between the seeping out of the ink from the back of the printed matter and the see-through of the printed characters is significant. It is well recognized.

[0082]

[Table 17]

[0083]

[Table 18]

[0084]

[Table 19]

From Tables 17 to 19, it can be seen that in Examples 1 to 41, high opacity was obtained, and particularly when an amine or an acid salt of amine was used, higher opacity was obtained. Even when the same additive compound is used, by setting the calcium ion concentration of the flotation system and the aluminum ion concentration within the desirable ranges of the present invention,
It can be seen that the opacity is improved. On the other hand, in Comparative Examples 1 to 3 in which no cationic compound, amine, acid salt of amine, and amphoteric compound were added to the flotation system and Comparative Example 4 in which the flotation process was performed at pH 8, high opacity was obtained. Absent.

Examples 42 to 55 and Comparative Example 5 Example 1 except that 0.5% by weight of EO ₁₀ PO ₁₀ random adduct of stearic acid (relative to raw material) was used as the deinking agent and the additive compounds shown in Table 20 were used. The deinking process was performed in the same manner as in, and the same evaluation as in Example 1 was performed. The results are shown in Table 20.

[0087]

[Table 20]

From the results shown in Table 20, the amine (II-a-1) and the acid salt of the amine (II-b-) were obtained as in Examples 45 and 46.
It can be seen that when 1) is used, higher opacity can be obtained even if the addition amount of the nonionic surfactant is the same.

Examples 56 to 82 and Comparative Examples 6 to 14 The following nonionic surfactants as deinking agents are shown in Table 21.
~ 22, warm water and Ca ions 15 after aging
The deinking treatment was performed in the same manner as in Example 1 except that 0 ppm was added and the additive compounds shown in Tables 21 to 22 were used, and the same evaluation as in Example 1 was performed. The results are shown in Tables 21-22. The nonionic surfactants in Tables 21 to 22 are as follows. Nonionic surfactant: Stearyl alcohol EO ₁₀ P
O ₁₅ block adduct (average number of moles added) Nonionic surfactant: tallow / glycerin (1/1) E
O ₇₀ PO ₁₀ mol Random addition product (average addition mol number) Nonionic surfactant: Dimer acid EO ₃₀ PO ₂₅ block addition product (average addition mol number)

[0090]

[Table 21]

[0091]

[Table 22]

From the results of Tables 21 to 22, Examples 56 to 8 were obtained.
2, the flotation system, the cationic compound,
It can be seen that the addition of amines, acid salts of amines and amphoteric compounds gives high opacity even when using various nonionic surfactants at different concentrations.

[0093]

EFFECTS OF THE INVENTION According to the present invention, deinked pulp having high opacity and excellent printing characteristics can be obtained with good yield from raw waste paper.

─────────────────────────────────────────────────── --- Continuation of the front page (56) Reference JP-A-59-53532 (JP, A) JP-A-5-186985 (JP, A) JP-A-4-163387 (JP, A) JP-A-52- 31563 (JP, A) JP-A-8-337984 (JP, A) JP-A-8-337985 (JP, A) Special Table 4-502038 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) D21C 5/02

Claims (11)

(57) [Claims] 1. A deinking method comprising at least a step of peeling ink from raw waste paper and a step of removing the peeled ink from a flotation system, wherein at least one non-inking method is used for peeling ink from waste paper. Using an ionic surfactant, and at least part of the flotation step in the presence of at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds, more than 9 to 12 or less. Method at a pH within the range. 2. A system for flotation containing at least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds and having a pH of 9 for the system.
The deinking method according to claim 1, wherein the deinking is carried out after the addition is carried out after adjusting the value within the range of from more than 12 to 12 or less. 3. At least one selected from the group consisting of cationic compounds, amines, acid salts of amines and amphoteric compounds is added in an amount of 0.001 to 5.0% by weight, based on the weight of waste paper. The deinking method according to claim 1 or 2, wherein 4. At least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound is a cationic compound, and the nonionic surfactant is 0 based on the weight of the waste paper. 0.25 to 5.0% by weight
The deinking method according to any one of claims 1 to 3, which is used in an amount of. 5. At least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound is an amine and / or an acid salt of an amine.
The deinking method according to any one of 3 above. 6. The deinking method according to claim 1, wherein at least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine, and an amphoteric compound is an amphoteric compound. 7. The deionizing agent according to claim 1, wherein the nonionic surfactant is selected from the group consisting of the following nonionic surfactants (A) to (D). Ink method. Nonionic Surfactant (A): Reaction Product Obtained by Adding Alkylene Oxide to Mixture of Oil and Fat Nonionic Surfactant (B): Formula: RCOO (AO) _m R ′
(Wherein R represents an alkyl or alkenyl group having 7 to 23 carbon atoms, and R'is a hydrogen atom, an alkyl group having 1 to 22 carbon atoms, an alkenyl group having 2 to 22 carbon atoms, or Represents an acyl group having 2 to 22 carbon atoms, AO is
An oxyalkylene group having 2 to 4 carbon atoms is shown, and m is an integer of 1 or more. ) Nonionic surfactant (C): compound represented by the formula: RO (AO) _n H (wherein R represents an alkyl or alkenyl group having 8 to 24 carbon atoms, and AO is 2 to 2 carbon atoms). 4 represents an oxyalkylene group, and n is an integer of 1 or more.) Nonionic surfactant (D): reaction product obtained by adding alkylene oxide to polyvalent carboxylic acid or its acid anhydride, Alternatively, a reaction product obtained by adding an alkylene oxide to a mixture of a polyvalent carboxylic acid or its acid anhydride and an alcohol. 8. The cationic compound is represented by the following formula (a ₁ )
a compound represented by (e ₁ ), a compound represented by the following formulas (f ₁ ) to (j ₁ ) and a cationic nitrogen content of 0.01 to 35% by weight,
A compound selected from the group consisting of cationic polymers having a weight average molecular weight of 2,000 to 3,000,000, and amines and acid salts of amines represented by the following formulas (a ₂ ) to (h ₂ ) and the following formulas (i ₂ ) ~ (L ₂ ), the amino nitrogen content is 0.
01-35% by weight and weight average molecular weight of 2,000-
Selected from the group consisting of a 3,000,000 polymers, amphoteric compound is a compound represented by the following formula _{(a 3) ~ (j 3} ), phospholipids (k _3), proteins (l ₃₎ and the following formula (m ₃₎ as well as
(n ₃ ), the cationic nitrogen content is 0.01 to 35% by weight, and the weight average molecular weight is 2,000 to 3,000,000.
8. The deinking method according to claim 1, wherein the deinking method is selected from the group consisting of amphoteric polymers [Chemical 1] [In the formulas (a ₁ ) to (e ₁ ), R ₁ and R ₂ are the same or different from each other and each represent an alkyl, alkenyl or β-hydroxyalkyl group having 10 to 24 carbon atoms, and R ₃ , R ₄ and R ₅ are the same or different from each other, and are each an alkyl or hydroxyalkyl group having 1 to 8 carbon atoms, a benzyl group, or a formula: — (AO) _n —Z
(Here, AO is a C2-C4 oxyalkylene group, Z is a hydrogen atom or an acyl group, and n is 1-5.
Is an integer of 0), R ₆ is an alkyl, alkenyl or β-hydroxyalkyl group having 8 to 36 carbon atoms, X ⁻ is a counter ion, and Y is 8 carbon atoms. To 36 alkyl, alkenyl or β-hydroxyalkyl group, a group represented by the formula: R ₆ COOCH ₂ — (wherein R ₆ is as defined above), the formula: R ₆ CONHC
A group represented by H ₂ — (wherein R ₆ is as defined above) or a group represented by the formula: R ₆ OCH ₂ — (wherein R ₆ is as defined above) is there. ] [Chemical 2] [In the formulas (f ₁ ) to (j ₁ ), R ₁ , R ₂ , R ₃ ,
R _6, R _7, R ₈ and _{R 9} are the same or different from each other, respectively, an alkyl group or an alkenyl group having a carbon number of 2 to 24 1 to 24 carbon atoms, _{R 4} and R ₅ are each The same or different, respectively, a hydrogen atom or a methyl group, X ⁻ and W ⁻ are the same or different, respectively, counterions, and Y and Z are the same or different, respectively, , O or NH, and AO
Is an oxyalkylene group having 2 to 4 carbon atoms, p and q are the same or different from each other, and are 1 to 10 respectively.
, R is an integer of 0 to 10, and l, m and n each have a weight average molecular weight of 2,000.
A positive number with a value in the range of ~ 3,000,000. ] [Chemical 3] [In the formulas (a ₂ ) to (h ₂ ), R ₁ has 8 to 36 carbon atoms.
An alkyl, alkenyl or β-hydroxyalkyl group of R ₂ and R ₃ are the same or different from each other,
Each is a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, HA represents an inorganic or organic acid, AO is an oxyalkylene group having 2 to 4 carbon atoms, l and m have l + m of 1 to 3, respectively.
00 is an integer of 0 or a positive integer, and W ₁ , W ₂ , W ₃ and W ₄ are the same or different from each other and are each a hydrogen atom or an alkyl group having 1 to 24 carbon atoms. Is. ] [Chemical 4] [In the formulas (i ₂ ) to (l ₂ ), R ₁ has 1 to 24 carbon atoms.
Or an alkenyl group having 2 to 24 carbon atoms, R ₂ , R ₃ and R ₆ are the same or different from each other, and each represent a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or 2 to 2 carbon atoms. 24 alkenyl groups, R ₄ and R
₅ are the same or different from each other and are a hydrogen atom or a methyl group, respectively, HA is an inorganic or organic acid, Y
Is O or NH, p is an integer of 1 to 10,
l, m and n are positive numbers such that the weight average molecular weight of the polymer is a value within the range of 2,000 to 3,000,000. ] [Chemical 5] [In the formulas (a ₃ ) to (j ₃ ), R ₁ , R ₂ and R ₃ are
1 to 24 carbon atoms, which are the same or different from each other
Or an alkenyl group having 2 to 24 carbon atoms, R ₄ is an alkyl, alkenyl or β-hydroxyalkyl group having 8 to 36 carbon atoms, M is a hydrogen atom,
Alkali metal atom, 1/2 mol of alkaline earth metal atom or ammonium group, and Y ₁ is represented by the formula: R ₅ NHCH ₂
CH ₂ — (wherein R ₅ is an alkyl group having 1 to 36 carbon atoms, or an alkenyl or hydroxyalkyl group having 2 to 36 carbon atoms), and Y ₂ is
Hydrogen atom or formula: R ₅ NHCH ₂ CH ₂ — (wherein R ₅
Is as defined above), Z is
₁ is a group represented by —CH ₂ COOM (where M is as defined above), Z ₂ is a hydrogen atom or a formula:
A group represented by —CH ₂ COOM (where M is as defined above). ] [Chemical 6] [In the formulas (m ₃ ) and (n ₃ ), R ₁ , R ₂ and R
₃ are the same or different from each other, respectively, a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, R ₄ and R ₅ are the same or different from each other, respectively, , A hydrogen atom or a methyl group,
M is a hydrogen atom, an alkali metal atom, 1/2 mol of an alkaline earth metal atom or an ammonium group, X ⁻ is a counter ion, Y is O or NH, p is 1 to 1
It is an integer of 0, and m and n are positive numbers such that the weight average molecular weight of the polymer is a value within the range of 2,000 to 3,000,000. ] 9. At least one selected from the group consisting of a cationic compound, an amine, an acid salt of an amine and an amphoteric compound is an amine represented by the following formula (a ₂ ) or (b ₂ ) and / or
The deinking method according to claim 8, which is an acid salt of an amine. [Chemical 7] [In the formula (a ₂ ) or (b ₂ ), R ₁ has 8 to 3 carbon atoms.
6 is an alkyl, alkenyl or β-hydroxyalkyl group, wherein R ₂ and R ₃ are the same or different from each other and are a hydrogen atom, an alkyl group having 1 to 24 carbon atoms or an alkenyl group having 2 to 24 carbon atoms, respectively. And HA represents an inorganic or organic acid. ] 10. The deinking method according to claim 1, wherein the flotation type calcium ion concentration is maintained at a concentration of 10 to 400 ppm. 11. The deinking method according to claim 1, wherein the aluminum ion concentration of the flotation system is maintained at a concentration of 0 to 40 ppm.