JP3301969B2 - Deinking method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a deinking method.

[0002]

2. Description of the Related Art In a deinking method, a deinking agent with less foam trouble is desired from the viewpoint of operability as well as the whiteness of the deinked paper, and various types of non-inking agents in which the order of alkylene oxide addition is specified. Ionic surfactants have been developed (JP-A-7-3681, JP-A-7-32429).
No. 2). However, the unstripped ink still remains, and the quality of the deinked paper is reduced.

[0003] The amount of the unstripped ink is reduced by increasing the amount of the deinking agent, but a bubble trouble occurs. Therefore, an antifoaming agent is added, but as seen in the flotation method,
Deinking requires an appropriate amount of foam and cannot be controlled sufficiently by adding an antifoaming agent.

[0004] It is an object of the present invention to provide a deinking method which enables both the problem of foam control and the deinking effect.

[0005]

The present invention provides a deinking method using a compound represented by the following general formula (a) and a deinking agent.

[0006]

Embedded image

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The compounds represented by the general formula (a) include urea, thiourea, thiourea dioxide, guanidine, formamide, carbohydrazide, guanylurea and the like. In addition, it is preferable to use a stable salt such as a hydrochloride or a phosphate in the form of a salt. The component (a) of the present invention is preferably a compound in which X ₃ in the formula (a) is O, S, or NH, and more preferably urea (X ₁ , X ₂ = NH ₂ , X ₃ ） O).

As the deinking agent [component (b)] of the present invention, a nonionic surfactant having a hydrophobic group having 14 to 44 carbon atoms is preferable, and particularly the following (b-1) to (b-) 3)
One or more selected from (B-1): a nonionic surfactant represented by the following general formula (b-1): R ¹ -O- (AO) _p -H (b-1) [wherein, R ¹ has 14 carbon atoms. An alkyl group or alkenyl group or an aryl group having 8 to 14 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, p is 1 to 300,
It preferably represents a number of 10 to 100. (B-1) is produced by adding an alkylene oxide to a monohydric alcohol or an alkylphenol by a known method. In particular, the molar ratio of ethylene oxide (EO) to propylene oxide (PO) is EO / PO = 1/5 to 5 /
Those added in 1 are preferred. Examples of the monohydric alcohol or alkylphenol include 1-tetradecanol and 1-tetradecanol.
Examples thereof include pentadecanol, 1-hexadecanol, 1-heptadecanol, 1-octadecanol, 1-nonadecanol, 1-eicosanol, 2-ethylhexanol, octylphenol, and nonylphenol.

(B-2): a nonionic surfactant represented by the following general formula (b-2): R ² —COO— (AO) _q —H (b-2) wherein R ² is An alkyl or alkenyl group having 13 to 23 carbon atoms or a group obtained by removing a carboxyl group from a polyvalent carboxylic acid having 14 to 44 carbon atoms, AO is an oxyalkylene group having 2 to 4 carbon atoms, q is 1 to 400, preferably 10
Represents the number of 100. (B-2) is produced by adding a C2 to C4 alkylene oxide to a fatty acid or polycarboxylic acid or esterifying a polyalkylene glycol by a known method. In particular, it is preferable to add ethylene oxide (EO) and propylene oxide (PO) in combination at a ratio of EO / PO = 1/5 to 5/1. As fatty acids,
Myristic acid, palmitic acid, stearic acid, oleic acid and the like, and polycarboxylic acids include octadecenylsuccinic acid and dimer acid.

(B-3): A mixture of a fat or oil having a fatty acid-derived acyl group having a carbon number in the range of 14 to 24 and a polyhydric alcohol, up to an average of 300 moles of alkylene oxide.
Preferably an adduct having 10 to 100 moles added. As the fats and oils of (b-3), vegetable oils such as coconut oil, palm oil, olive oil, soybean oil, rapeseed oil, linseed oil, animal oils such as lard, tallow, bone oil, fish oil, and hardened oils thereof, and semi-hardened oils Examples of the oil include oils, and recovered oils obtained in the step of refining these oils and fats. Examples of the polyhydric alcohol include dihydric to tetrahydric alcohols having 2 to 5 carbon atoms, such as ethylene glycol, propylene glycol, and glycerin, and glycerin is preferable. The mixing ratio of the fats and oils and the polyhydric alcohol is 1 / 0.0.
It is preferably from 0.5 to 1/6, particularly preferably from 1 / 0.1 to 1/2. Examples of the alkylene oxide include ethylene oxide and propylene oxide.

In order to enhance the cohesiveness of the ink, a fatty acid having 14 to 24 carbon atoms, a polycarboxylic acid having 14 to 44 carbon atoms, a dimer acid and salts thereof may be used in combination.

The total amount of the components (a) and (b) is preferably from 0.01 to 5 parts by weight, particularly preferably from 0.1 to 1 part by weight, per 100 parts by weight of the used paper. The weight ratio of component (a) to component (b) is (a) / (b) = 1/99
To 99/1, more preferably 30/70 to 7
0/30.

Since the component (a) of the present invention has no foaming property and is excellent in swelling ability of cellulose, the ink of the component (b)
It is considered that permeation between celluloses is facilitated, and good ink peeling is possible. Therefore, even if the amount of the component (b) is reduced, a good deinking effect can be obtained. Further, by maintaining the amount of the component (b) and adding the component (a), the ink peeling can be promoted without changing the foaming property.

In the present invention, known alkaline agents such as sodium hydroxide and sodium silicate, bleaching agents such as hydrogen peroxide, hypochlorite and hyposulfite, alkylbenzene sulfonate,
Foaming agents such as higher alcohol sulfates, pitch control agents, and sequestering agents such as EDTA and DTPA can also be used.

In the deinking method, the ink removing step, the bleaching step, the ink removing step and the like are appropriately combined. The deinking method of the present invention employs a flotation method in the ink removing step because of easy control of bubbles. Preferred for the method used. In addition, the ink peeling step is a step of peeling the ink from the used paper raw material using a pulper, a kneader, a chemical mixer, or the like. The flotation step is a step of separating the pulp and the ink by foaming the pulp-water slurry by appropriate means such as physical or chemical, attaching the ink particles to the air bubbles, and discharging the air bubbles. is there. Other steps can be performed according to a conventionally known deinking method, and each step can be performed a plurality of times. The component (a) and the component (b) may be added at any time during the deinking process, and both may be added as a single liquid or separately. The component (b) is preferably added in the ink peeling step. Since the components (a) and (b) complementarily promote the ink peeling, the components (a) and (b) are added in the ink peeling step. It is particularly preferred that the components coexist.

[0016]

EXAMPLES Examples 1 to 18 and Comparative Examples 1 to 4 [Deinking treatment] Waste paper raw material (newspaper / flyer = 6/4) 10
0 parts by weight (absolute dry weight) was placed in a tabletop disintegrator, and 0.5 parts by weight of caustic soda, the components (a) and (b) in the amounts shown in Table 1 were added.
Add 2000 parts by weight of hot water at 0 ° C. and 3,000 minutes for 10 minutes.
Disintegration processing was performed at rpm. Then, the pulp concentration was adjusted to 15
After the concentration, sodium hydroxide, No. 3, sodium silicate and hydrogen peroxide were added in 0.5 parts by weight, 1.5 parts by weight, and 0.5 parts by weight, respectively, and bleaching treatment was performed at 55 ° C. for 120 minutes. Thereafter, the pulp concentration was diluted to 5% with warm industrial water at 40 ° C.
Re-disintegration was performed at 000 rpm for 1 minute. Subsequently, the slurry was diluted with industrial water at 40 ° C. to a pulp concentration of 1%, and subjected to a flotation treatment at an air supply rate of 1.50 liters per liter of pulp liquid for 6 minutes. Thereafter, the slurry was concentrated to a pulp concentration of 13%, diluted again with industrial water to 1%, and diluted with industrial water to 15% in accordance with JIS P 8209-1976.
A handsheet having a basis weight of 150 g / cm ² was prepared using a 0-mesh wire and used as Sample 1. Also, the slurry concentrated to a pulp concentration of 13% after the flotation treatment is used.
After diluting with a 200-fold amount of industrial water, the operation of concentrating the pulp concentration to 13% was repeated four times, and a sheet was prepared in the same manner as described above to obtain Sample 2.

[Evaluation of Performance] The following evaluation was performed in the above-described deinking method. Table 2 shows the results. The whiteness of Sample 1 (according to JIS P8123-1961) was 53-54% in Comparative Examples 1-4, and was 55-56% in Examples 1-18.

(I) Behavior of foam in flotation treatment Two minutes after the start of flotation, the height from the slurry surface to the upper layer of the floss layer was measured.

(Ii) Area ratio of unstripped ink of Sample 2 Measured with an image analyzer at a magnification of 20 times and calculated by the following equation. Unstripped ink area ratio (%) = (S / F ) × 100 S; ink area measured during 100 field (mm ²⁾ F; 100 field total area 15000 ² (1 viewing area of 150 mm ²⁾ of unpeeled If the ink area ratio is 0.30% or less, unexfoliated ink is at a level where no unpeeled ink is observed even when carefully observed,
If it is more than 0.30% and 0.40% or less, the unstripped ink is at a level that can be visually confirmed.
The unstripped ink of about mm is clearly confirmed by visual inspection, and has a level that affects printing.

[0020]

[Table 1]

(Note) * 1: Addition with hydrochloride salt * 2: Addition with phosphate salt In Table 1 (b), EO and PO in parentheses () unless otherwise specified mean random addition.

[0022]

[Table 2]

[0023]

According to the present invention, a high-quality deinked pulp having a high whiteness and a very small amount of unstripped ink can be obtained, and it is possible to eliminate bubble troubles during the deinking operation and to reduce the total cost. A method is provided.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-194289 (JP, A) JP-A-6-73683 (JP, A) JP-A-7-145583 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) D21C 5/02

Claims (4)

(57) [Claims] 1. A deinking method using a flotation method using a compound represented by the following general formula (a) and a deinking agent. Embedded image 2. The deinking method according to claim 1, wherein the deinking agent contains a nonionic surfactant having a hydrophobic group having 14 to 44 carbon atoms. 3. The weight ratio of the compound represented by the general formula (a) to the deinking agent (b) is (a) / (b) = 1/99 to 99.
3. The deinking method according to claim 1, wherein Wherein said formula compound and deinking represented by (a) (b), deinking method according to claim 1 or one of claims 3 to be used in the step of peeling the ink from Furnish .