JPH06257085A - Deinking agent for reclaiming waste paper - Google Patents

Abstract

PURPOSE:To obtain a deinkig agent for reclaiming waste paper, capable of efficiently peeling an ink from printed waste paper in a disintegrating step and providing reclaimed pulp having high whiteness and hardly any residual ink and excellent in collecting power and moderate foaming of the peeled ink in flotation treatment. CONSTITUTION:This deinking agent for reclaiming waste paper comprises (a) a compound expressed by formula I and (b) a 12-24C higher fatty acid or its salt. R<1>O-(PO)m-(EO)n(XO)k-R<2> (I) (R<1> is 12-22C alkyl or alkenyl group; R<2> is hydrogen or 2-24C acyl group; PO, EO and XO each are propylene oxide, ethylene oxide and >=3C alkylene oxide units; m is 1-8; n is 10-40; k is a number providing 3-120 sum total of carbon atoms in polymerized XO; the addition form of PO and EO is block).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to newspapers, magazines, and copy OA.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a used deinking agent for recycling used paper when obtaining recycled pulp from used printed paper, and more particularly to a deinking agent for recycled used paper suitable for use in the flotation method.

[0002]

2. Description of the Related Art It has long been practiced to recycle printed waste paper and use it again as a raw material for papermaking. However, in recent years, from the standpoint of effective use of resources and environmental protection, recycling of printed waste paper has become more important, and the use of recycled pulp is expanding. When recycled printed waste paper is usually reused with a disintegrator such as pulper, an alkali agent such as caustic soda, sodium carbonate, sodium silicate, bleaching agent such as hydrogen peroxide, sodium hypochlorite, EDTA, D
Along with chelating agents such as TPA, anionic activators such as fatty acids, alkylbenzene sulfonates, α-olefin sulfonates, higher alcohol sulfates, dialkyl sulfosuccinates, higher alcohols, alkylphenols, fatty acids, etc. Nonionic activators such as alkylene oxide adducts of alkanol oxides and alkanol amides have been used alone or in combination of two or more. On the other hand, from the point of view of the deinking device, in the disaggregation process, in order to efficiently separate the ink from the pulp, the kneader, refiner, disperser, etc. were improved, and in the flotation process, an appropriate amount of air was used. In order to remove the peeling ink efficiently by adjusting the bubble diameter and bubble diameter, high floatator, multi-injector, PD
There are improved devices such as M cells. However, the above deinking agent has an insufficient ability to collect the peeled ink, and it has not been possible to obtain a high-quality recycled pulp having high whiteness and less residual ink. Moreover, the foaming property of the deinking agent is too strong,
There are problems such as inability to perform stable operations, such as the fact that bubbles cannot be scraped out by the flotation process, the yield decreases and the production capacity decreases.

In recent years, many patents have been filed regarding deinking agents for higher alcohol type nonionic surfactants and methods for using them. For example, a method for deinking used paper using a mixture of ethylene oxide and propylene oxide added to an alcohol and an alkylphenol in a range of 50 to 95% ethylene oxide (JP-A No. 6-52138).
No. 5-51891), a method for deinking used paper using a mixture of alcohol and alkylphenol with 1 to 50 mol of propylene oxide and a mixture of ethylene oxide and propylene oxide (JP-A-55-5).
No. 1892), a deinking agent for recycling used paper using a mixture of alcohol and alkylphenol with 3 to 20 mol of ethylene oxide and a mixture of ethylene oxide and propylene oxide (JP-A-62-250291).
However, since the product obtained by the addition method in which these alkylene oxides are mixed contains a large amount of ethylene oxide at the end, it acts strongly as a hydrophilicity, and the peeling force of the ink and the trapping of the ink. Ink is not efficiently collected from the pulp due to its weak gathering power, and high quality recycled pulp with high whiteness and low residual ink cannot be obtained.
Further, in recent deinking devices, there are problems that the foaming property is too strong and bubbles overflow during the flotation process, the yield of pulp decreases, and stable operation cannot be performed.

Further, a deinking agent obtained by adding propylene oxide or a mixture of propylene oxide and ethylene oxide (containing 80% or more of propylene oxide) to an alcohol having 2 to 12 carbon atoms and sequentially adding ethylene oxide (JP-A-51-84905). However, since a large amount of propylene oxide is added to a short-chain alcohol, the action as a hydrophobicity becomes too strong, the peeling power and collecting power of the ink are reduced, and the high whiteness is regenerated. I can't get pulp. Further, a product obtained by sulfating a higher alcohol with an adduct of propylene oxide and 5 to 25 mol of ethylene oxide and 1 to 10 of propylene oxide in the higher alcohol.
Although a deinking agent for recycling recycled paper (Japanese Patent Application Laid-Open No. 56-79795) containing 100 to 0 to 20/80 moles of the successive addition product has been proposed, the successive addition product has a strong ink peeling power, but the ink. The collected power is weak and a high whiteness recycled pulp cannot be obtained. However, the amount of bubbles during the flotation treatment can be adjusted appropriately by using the higher alcohol sulfate in combination.

[0005]

DISCLOSURE OF THE INVENTION The present invention efficiently separates ink from printed waste paper in a disaggregation step, and is excellent in collecting power of the separated ink and proper foaming in the flotation process, and has high whiteness and residual ink. It is an object of the present invention to provide a deinking agent for recycling used paper that can produce recycled pulp with less waste.

[0006]

DISCLOSURE OF THE INVENTION The present invention is based on the finding that the above problems can be efficiently solved by using a propylene-ethylene block addition type nonionic deinking agent having a specific structure in combination with a fatty acid or a salt thereof. It was done based on this. That is, the present invention provides a deinking agent for recycling used paper, comprising (a) a compound represented by the following general formula I and (b) a higher fatty acid having 12 to 24 carbon atoms or a salt thereof.

Embedded image R ¹ O— (PO) m- (EO) n- (XO) k—R ² (I) (wherein R ¹ is an alkyl or alkenyl group having 12 to 22 carbon atoms, and R ² is Hydrogen or an acyl group having 2 to 24 carbon atoms,
PO, EO, and XO are a propylene oxide unit, an ethylene oxide unit, and an alkylene oxide unit having 3 or more carbon atoms, respectively, and m = 1 to 8 and n = 10 to 4
0 and k are numbers in which the total number of carbon atoms of polymerized XO is 3 to 120. Further, in the formula, the addition form of PO and EO is a block. )

Further, there is also provided a deinking agent for recycling used paper, which comprises using (c) the compound represented by the general formula II in combination with the deinking agent. According to this, it is possible to adjust to proper foaming during the operation.

Embedded image R ³ O (AO) p SO ₃ M (II) (wherein, R ³ represents an alkyl group or an alkenyl group having 12 to 24 carbon atoms, AO represents ethylene oxide and / or propylene oxide, and p is 1 To M are hydrogen, an alkali metal, ammonium or an alkanolamine.) The ether compound represented by the general formula I, which is the component (a) of the present invention, has a higher carbon number of 12 to 22. It can be produced by first adding propylene oxide to alcohol, adding ethylene oxide to the terminal hydroxyl group, and further adding XO which is an alkylene oxide having 3 or more carbon atoms. Next, if desired, the terminal hydroxyl group may be reacted with a carboxylic acid having 2 to 24 carbon atoms for esterification. Here, the XO singly or the polyoxyalkylene group formed by polymerization is hydrophobic and has a total carbon number of 3 to 120. Here, two or more kinds of alkylene oxides may be block- or random-added as XO. XO which is an alkylene oxide having 3 or more carbon atoms
Examples thereof include propylene oxide, butylene oxide, butadiene oxide, hexylene oxide, styrene oxide and α-olefin oxide. Among these, alkylene oxides having 3 to 30 carbon atoms are preferable, and propylene oxide is particularly preferable.

In the ether compound represented by the general formula I, the molecular weight of the (EO) n portion and the (XO) k-R
The ratio of the molecular weights of the ^two parts is preferably 0.2 to 2.0, more preferably 0.3 to 1.8. The ether compound represented by the general formula I having the above structure has a high affinity with ink as compared with a known higher alcohol deinking agent, and therefore has a strong ink peeling force and is particularly suitable for an offset ink which is difficult to peel off. On the other hand, the effect of removing ink is high. Further, since the mixing in a specific range (EO) n moiety and (XO) k-R ² moiety at a specific ratio, it has high affinity at the time of hydrophobic strong flotation and peeled ink Therefore, it has an excellent ability to collect fine ink of 4 μm or less, which was difficult in the past. Therefore, the ink separated in the flotation process can be efficiently separated and removed from the pulp by the bubbles, and as a result, a regenerated pulp having a high whiteness and a low dullness and a high b value can be obtained. If this molecular weight ratio exceeds 2.0, the hydrophilicity increases, and the ink affinity and the ink collecting power during flotation treatment weaken. On the other hand, when the molecular weight ratio is less than 0.2, foaming is low in the flotation process, the foam is not sufficiently scraped off, and the ink collecting power is lowered in the flotation process. When the molecular weight ratio is 0.3 to 1.8, the ink collecting power is further improved. In formula II,
m = 1 to 8, n = 10 to 40, k is a number such that the total number of carbon atoms of the polymerized XO is 3 to 120, and 1 to 6, respectively.
12-35 and 15-120 are preferred. When XO is propylene oxide and R ² is hydrogen, the sum of m and k is preferably 8 to 35, and particularly 11 to 35 is preferable.

The higher alcohol forming the alcohol residue of R ¹ has 12 to 22 carbon atoms, preferably 16 to 12 carbon atoms.
22 and more preferably 18 to 22 linear higher alcohols. Examples of such higher alcohols include lauryl alcohol, myristyl alcohol, palmityl alcohol, stearyl alcohol, nonadeca alcohol, elaidyl alcohol, behenyl alcohol, oleyl alcohol and alcohol derived from animal and vegetable fats and oils fatty acids, such as beef tallow alcohol, fish oil alcohol, pork. Examples include fatty alcohols and cured products thereof. R ² is hydrogen or an acyl group having 2 to 24 carbon atoms, preferably 2 to 12 carbon atoms, and particularly preferably hydrogen.

When the carbon number of the higher alcohol of the above-mentioned deinking agent is shorter than the above range, the hydrophobicity is insufficient due to the short chain length of the alkyl group, and the molecular weight ratio of ethylene oxide and alkylene oxide or its acyl compound is within the above range. However, the ability to collect the separated ink in the flotation process is insufficient, and it is not possible to obtain a high-quality recycled pulp with high whiteness. On the other hand, when the alkyl group is longer than the above range, the deinking agent does not dissolve or disperse during disaggregation, so that it is not possible to obtain a high-quality pulp having high whiteness and low residual ink. In the present invention, when the above ether compound is produced, the water content in the reaction system is set to 0.3% or less, and the catalyst is a basic catalyst such as sodium hydroxide or potassium hydroxide, or a magnesium oxide-aluminum solid catalyst is added. The amount of the intermediate product in each alkylene oxide addition step is always 0.35% or less with respect to the final product, and the addition can be performed under the conditions of the alkylene oxide addition reaction which is generally performed. Incidentally, the addition of alkylene oxide to higher alcohols can be carried out by reacting the alkylene oxide for several hours at about 100 to 200 ° C. and 1 to 3 kg / cm ² in the presence of a catalytic amount of potassium hydroxide.

The by-products polyethylene glycol, polypropylene glycol and polyalkylene oxide such as ethylene oxide-propylene oxide copolymer contained in the product thus obtained are contained in an amount of about 0.1 to about 5.
% By weight, preferably 0.3 to 3% by weight. However, it is also possible to add the polyalkylene glycol within the above range after the above ether compound is produced. And, at least one kind of the above-mentioned ether compound is 99.9 to 95% by weight and the by-product is about 0.1 to 5%.
It is preferred to use a weight% mixture as component (a).

The component (b) of the present invention contains 12 to 24 carbon atoms.
Of saturated, unsaturated, linear or branched chain fatty acids or salts thereof, for example, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, margaric acid, palmitic acid, stearic acid, elaidic acid, behenic acid, oleic acid, Examples thereof include linoleic acid, linoleic acid, tallow fatty acid, tallow-hardened fatty acid, palm oil fatty acid, coconut oil fatty acid, and the like, and these may be used alone or as a mixture. Examples of the salts include alkyl metal salts such as sodium and potassium, alkaline earth metal salts, ammonium salts, amine salts such as alkanolamine salts.

The compound represented by the general formula II which is the component (c) of the present invention can be produced by adding an alkylene oxide to a higher alcohol having 12 to 24 carbon atoms and further sulfating the terminal hydroxyl group. . R ³ has 1 carbon atom
2 to 24, preferably 12 to 16 alkyl or alkenyl groups. AO is ethylene oxide or propylene oxide, either alone or as a mixture, and the number of added moles p thereof is 1 to 8 moles. When a mixture of ethylene oxide or propylene oxide is used, it may be block or random addition. The compound represented by the general formula II having such a structure is excellent in foaming property during flotation treatment. The sulphated product can be produced by sulphating an alkylene oxide adduct of a higher alcohol with chlorosulfonic acid or sulfuric anhydride under the conditions generally used. In the present invention, an unneutralized product can be used,
If desired, alkali metals such as sodium and potassium,
You may neutralize with ammonium or an alkanolamine.

In the deinking agent of the present invention, the components (a) and (b) are
The ratio can be arbitrary, but the weight ratio of the components (a) and (b) is preferably 90/10 to 60/40, particularly preferably 90/10 to 70/30. When using the component (c), the component (a) +
The weight ratio of the total amount of (b) and (c) is preferably 95/5 to 55/45. That is, when the amount is within these ranges, the amount of foaming can be easily adjusted, the quality of the recycled pulp is not deteriorated due to the decrease in the ink collecting power during the flotation process, and the operation stability can be secured. The deinking agent of the present invention is an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, a polymer surfactant, a polymer dispersion flocculant, within the scope of achieving the object of the present invention. It is also possible to use enzymes in combination.

The components (a) and (b) of the present invention, or a mixture of these components and the component (c), may be added separately in the waste paper disaggregation step, the aging step or both steps, or the component (a).
Even when the component (b) or (c) is added in portions during the flotation step and the component (b) or (c) is added in portions during the flotation treatment, a good effect is exhibited if the mixing ratio is the above-mentioned mixing ratio. The amount of addition is preferably 0.1 to 2% by weight (hereinafter abbreviated as%) with respect to the raw waste paper. Within this range, it is possible to obtain high-quality recycled pulp with high whiteness and low residual ink, and to obtain stable operation. When the deinking treatment is performed using the product of the present invention, a bleaching agent such as sodium hydroxide, sodium silicate, or sodium carbonate as an alkaline agent in addition to the product of the present invention in the disintegration step and hydrogen peroxide as the case may be. In combination with pulp concentration of 4 to 25%, temperature of 20 to 70
C, pH = 7.5-11.5, preferably 8.0-1
It is preferable to use 1.5. When the pulp concentration is 3% or less or 20 ° C. or less, the frictional force between pulp fibers is small at the time of disaggregation, so that the amount of undisaggregated pulp becomes large, the pulp cannot be used as a papermaking raw material, and the residual ink becomes large. On the other hand, when the pulp concentration is 25% or more and the temperature is 70 ° C. or more, the frictional force between pulp fibers is too strong, or the paper strength of the regenerated pulp produced by heat is weakened, and high quality regenerated pulp cannot be obtained. . Further, if the pH during disaggregation is 7.5 or less, the degree of swelling of pulp fibers during disaggregation is low, so that the amount of undisaggregated fibers becomes large and it cannot be used as a raw material for papermaking, or the amount of residual ink becomes high, which is high. Unable to obtain quality recycled pulp. On the other hand, when the pH is 11.5 or higher, the yellowing of the pulp occurs due to alkaline burning, the whiteness is lowered, and the paper strength is lowered.

The aging step can be carried out under the same chemical conditions as in the disaggregation step. At this time, the pulp concentration is 10 to 30%,
Aging is preferably performed at a temperature of 30 to 80 ° C. for 1 hour or more. If the pulp concentration is 10% or less and the temperature is 30 ° C. or less, a sufficient aging effect cannot be obtained, and high quality recycled pulp cannot be obtained. Further, at 80 ° C. or higher, there is a drawback that the paper strength is lowered by heat. Further, when the pulp concentration is 30% or more, a sufficient wet oil state cannot be obtained and the aging effect cannot be obtained. The peeled ink has a pulp concentration of 0.5-1.5%,
By performing flotation at a temperature of 20 to 45 ° C, it can be efficiently removed from the pulp slurry. Furthermore, even if the product of the present invention has a step which is usually used in the deinking treatment step such as dilution dehydration, screen, disperser, and kneader treatment step, the quality and operability of the recycled pulp are Does not affect, apart from the above defibration and aging steps, a step of peeling the ink, for example, a kneader,
The deinking agent may be added to a refiner, a disperser or the like.

[0017]

EFFECT OF THE INVENTION A known deinking agent obtained by sequentially polymerizing ethylene oxide and propylene oxide in alcohol has moderately high ink peeling power and ink collecting power, but its foaming property during flotation treatment is weak. However, the foam cannot be sufficiently scraped off, and recycled pulp with high whiteness cannot be obtained. On the other hand, a mixture obtained by adding a mixture of ethylene oxide and propylene oxide to alcohol cannot obtain a regenerated pulp with high whiteness because the ink peeling power and the ink collecting power are weak. Further, since the foaming property during the flotation treatment is strong, the amount of bubbles becomes too large and stable operation cannot be obtained. However, when the compound of the component (a) of the present invention is used, the ink peeling power and the ink collecting power can be strengthened, and when the fatty acid or salt of the component (b) is used in combination, fine ink is also collected by a synergistic effect. It is possible to obtain high quality recycled pulp without "dullness". Furthermore, the component (c)
By mixing the compound shown in, it is possible to properly adjust the foaming property during the flotation process due to the fluctuation of the used waste paper such as newspaper wastes, leaflets, and copy OA waste papers that deteriorated in the summer. It is possible to maintain a good operability state without overflow or reduction in pulp yield. Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0018]

【Example】

Production Example Stearyl alcohol (1 mol) and a catalytic amount of KOH were charged into an autoclave, and after nitrogen substitution, dehydration was carried out under reduced pressure to make the water content in the system 0.07%, and propylene oxide (3
Mol) at 125 ° C. at 3.0 kg / cm ² or less, and aged for P
An O adduct was obtained. Subsequently, ethylene oxide (30
Mol) at 160 ° C., 3.0 kg / cm ² or less, and aged P
An O-EO adduct was obtained. Furthermore, propylene oxide (14
Mol) at 125 ° C. at 3.0 kg / cm ² or less, and aged for P
An O-EO-PO adduct was obtained (deinking agent a-1). Deinking agents a-2 to 4 were manufactured in the same manner.

Example Used raw printing paper (offset printing waste paper / letters printing waste paper /
(Chirashi = 4/3/3 weight ratio) was cut into 3 x 3 cm, put into a pulp disintegrator, and caustic soda 1.0%, No. 3 sodium silicate 3.5%, hydrogen peroxide (based on the weight of the used waste paper) Active ingredient) 1.0%, and the deinking agents of Table-1 and Table-2
After adding 0.35% in the addition ratio shown in 3, hot water was added so that the pulp concentration would be 15%, and disintegration treatment was performed at 55 ° C. for 15 minutes. The obtained pulp slurry is heated to 65 ° C., 60
Soaking for 5 minutes and adding water to this to give a pulp concentration of 5
The disaggregation treatment was performed for 1 minute. Thereafter, warm water was added to dilute the pulp to a concentration of 1%, and a flotation treatment was performed at 30 ° C. for 7 minutes. Next, the pulp slurry after the flotation treatment was concentrated to 10% and then diluted to 1% with water to prepare a pulp sheet with a tapping sheet machine. The whiteness of the obtained pulp sheet was measured with a colorimeter and the residual ink area ratio was measured with an image analyzer. The results are shown in Table-3.
In the table, “dullness” is not always proportional to the apparent color tone even if the whiteness of recycled paper is high. for that reason,
The evaluation was carried out on a 3-point scale by visual judgment of the pulp sheet. 1: Dullness was conspicuous, 2: Dullness was slightly present, 3: Dullness was not observed Further, operability (foam) during flotation treatment was evaluated according to the following criteria. A: Good operability B: Little foam but no operability problem D: Too many bubbles and no operability C: Little foam but no operability problem E: Too few bubbles and no operability

[0020]

[Table 1] Table-1 Deinking agent a component R ¹ O- (PO) m- (EO) n- (XO) k-R ² Deinking No. alkyl group m / n (XO) k- R 2 M 1 / M 2 The total number of carbon atoms of the by-product _{(wt%) a-1 C 18 3,30} 42 1.62 0.56 a- 2 C ₂₀ 1,35 60 1.32 1.98 a-3 C ₁₆ 4,25 60 1.02 1.37 a-4 C ₂₂ 6,12 92 0.36 2.81 * M ₁ is (EO ) N has a molecular weight M ₂ is (XO) k—R ^{2 has} a molecular weight XO is propylene oxide (No 1, ² , 4) or butylene oxide (No 3), and R ² is hydrogen (No 1 to No 1).
3) or a methyl ester group (No4).

[0021]

[Table 2] Table-2 Deinking agent c component [R ³ O (A
O) p SO ₃ M] No. R ³ AO *) Type of M Alkyl group Type and number of added moles p c-1 C ₁₄ EO ₃ Potassium c-2 C ₁₂ PO ₅ EO ₃ (block) Sodium c-3 C _12-15 EO ₂ PO ₂ (random ) Triethanolamine ─────────────────────────────────── *) EO is ethylene oxide, PO is propylene oxide Show.

[0022]

[Table 3] Table-3 Evaluation results No. a component / fatty acid / c component weight ratio Whiteness Number of residual inks *) Dull runnability 1 a-1 / stearic acid (90/10) 56.2 0.241 3 C 2 a-3 / beef tallow fatty acid sodium 56 .07 0.216 3 C (60/40) 3 a-2 / beef tallow fatty acid / C-1 57.0 0.208 3 A (81/9/10) 4 a-1 / palm oil fatty acid potassium 57. 5 0.165 3 A / C-2 (60/15/25) 5 a-4 / coconut oil fatty acid / C-3 57.3 0.182 3 B (36/24/40) 6 a-4 55. 8 0.274 2 C 7 C-1 51.9 1.158 1 D 8 tallow alcohol PO ₅ EO ₁₀ H 52.2 1.094 2 A / tallow fatty acid potassium (80/20) 9 C ₁₈ H ₃₇ O ( EO ₄₀ / PO ₁₀ ) H 52.5 1.047 2 E (R form) / stearic acid (50/50) 10 C ₁₈ H ₃₇ OEO ₁₅ PO ₅ H / linoleic acid / C ₁₂ H ₂₅ OPO ₂ SO ₃ NH ₄ (65/10/25) 53.1 0.973 2 A No 1 to 5 are examples, and No. 6 to 10 are comparative examples. In the table, *) unit (pieces / field) R body indicates a random body.

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[Procedure amendment]

[Submission date] August 18, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

Example Used raw printing paper (offset printing waste paper / letters printing waste paper /
(Chirashi = 4/3/3 weight ratio) was cut into 3 x 3 cm, put into a pulp disintegrator, and caustic soda 1.0%, No. 3 sodium silicate 3.5%, hydrogen peroxide (based on the weight of the used waste paper) Active ingredient) 1.0%, and the deinking agents of Table-1 and Table-2
After adding 0.35% in the addition ratio shown in 3, hot water was added so that the pulp concentration would be 15%, and disintegration treatment was performed at 55 ° C. for 15 minutes. The obtained pulp slurry is heated to 65 ° C., 60
Soaking for 5 minutes and adding water to this to give a pulp concentration of 5
The disaggregation treatment was performed for 1 minute. Thereafter, warm water was added to dilute the pulp to a concentration of 1%, and a flotation treatment was performed at 30 ° C. for 7 minutes. Next, the pulp slurry after the flotation treatment was concentrated to 10% and then diluted to 1% with water to prepare a pulp sheet with a tapping sheet machine. In addition, at the time of disaggregation
The pH was 10.4 and the pH during soaking was 10.3.
It was The whiteness of the obtained pulp sheet was measured with a colorimeter and the residual ink area ratio was measured with an image analyzer. The results are shown in Table-3. In the table, “dullness” is not always proportional to the apparent color tone even if the whiteness of recycled paper is high. Therefore, the visual evaluation of the pulp sheet was performed in a three-stage evaluation. 1: Dullness was conspicuous, 2: Dullness was slightly present, 3: Dullness was not observed Further, operability (foam) during flotation treatment was evaluated according to the following criteria. A: Good operability B: Little foam but no operability problem D: Too many bubbles and no operability C: Little foam but no operability problem E: Too few bubbles and no operability

Claims (4)

[Claims] 1. A deinking agent for recycling used paper, which comprises (a) a compound represented by the following general formula I and (b) a higher fatty acid having 12 to 24 carbon atoms or a salt thereof. Embedded image R ¹ O— (PO) m- (EO) n- (XO) k—R ² (I) (wherein R ¹ is an alkyl or alkenyl group having 12 to 22 carbon atoms, and R ² is Hydrogen or an acyl group having 2 to 24 carbon atoms,
PO, EO, and XO are a propylene oxide unit, an ethylene oxide unit, and an alkylene oxide unit having 3 or more carbon atoms, respectively, and m = 1 to 8 and n = 10 to 4
0 and k are numbers in which the total number of carbon atoms of polymerized XO is 3 to 120. Further, in the formula, the addition form of PO and EO is a block. ) 2. The deinking agent for recycling used paper according to claim 1, further comprising (c) a compound represented by the general formula II. Embedded image R ³ O (AO) p SO ₃ M (II) (wherein R ³ is an alkyl group or an alkenyl group having 12 to 24 carbon atoms, AO is ethylene oxide and / or propylene oxide, and p is 1 Represents a number of 8 and M is hydrogen, alkali metal, ammonium or alkanolamine.) 3. Component (a) / (b) is 90 / 10-60
The deinking agent for recycling used paper according to claim 1 or 2, having a weight ratio of / 40. 4. The sum of the components (a) + (b) / (c) is 9
The deinking agent for recycling used paper according to claim 2, which has a weight ratio of 5/5 to 55/45.