JP2931438B2 - Deinking agent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deinking agent used for recycling used paper such as newspapers, magazines and OA used paper. More specifically, a deinking agent that can obtain a deinked pulp having a high b value and a small amount of unstripped ink when deinking a newspaper, magazine, OA waste paper, etc. by a flotation method, a cleaning method or a compromise method thereof. About.

[0002]

BACKGROUND OF THE INVENTION Newspapers,
Recycling of magazines, OA waste paper, and the like has been practiced for a long time, but recently, in conjunction with global environmental issues such as protection of forest resources and garbage disposal, the effective use of waste paper is increasing in importance. In addition, the use of deinked pulp has been advanced to higher-grade pulp as seen in the example of used newspaper to medium-grade paper. On the other hand, recently used paper is becoming more severe from the viewpoint of deinking due to changes in printing technology, printing method, printing ink components, and the like. Therefore, in order to further promote deinking, improvements have been made to the apparatus. Chemicals conventionally used to separate and remove ink and other impurities from waste paper include alkaline agents such as caustic soda, sodium silicate, sodium carbonate, and sodium phosphate, hydrogen peroxide, hyposulfite, and hypochlorite. Bleaching agents such as acid salts, sequestering agents such as EDTA and DTPA, and anionic agents such as alkylbenzene sulfonates, higher alcohol sulfates, α-olefin sulfonates, and dialkyl sulfosuccinates as deinking agents. Agents, higher alcohols, non-ionic activators such as ethylene oxide adducts of alkylphenols and fatty acids, and alkanolamides have been used alone or in combination of two or more. However, these deinking agents have a high foaming property in the flotation process, but have a low ink collecting ability.The cleaning method has a low detergency. And resulted in only low grade deinked pulp. Furthermore, because there is dullness even with high whiteness,
The use of bleaching agents had to be increased in order to eliminate the use of deinked pulp (for example, reducing the amount of paperboard used below and below, and reducing the amount used in newspapers) and eliminating dullness. To obtain a deinked pulp having a dull color and a bright color tone, the b value of the Hunter color difference type Lab display system may be increased. The deinked pulp having a high b value has a high removal rate of fine ink of 4 μm or less. If the b value is high, the color tone of the pulp becomes bright, so that the use of bleaching agents such as hydrogen peroxide can be reduced, the deinked pulp can be highly blended, and it can be used for one-grade applications.

[0003] There are two methods for increasing the b value, such as a method of efficiently removing fine ink of 4 µm or less as described above, or a method of using a large amount of alkalis.
However, the latter has the disadvantage that sticky (adhesive) increases, drainage load increases, and pulp becomes brittle. There are some examples of the former technique for collecting and removing fine ink of 4 μm or less, but none of them is effective.

[0004] Higher fatty acids have long been known as deinking agents having a large ink collecting ability. For example, Japanese Patent Registration No. 80988, Japanese Patent Registration No. 82089, and Japanese Patent Registration No. 83901 disclose the use as a deinking agent having excellent ink collecting ability when used alone. Also, JP-A-51-13762, JP-A-53-130309, and JP-A-54-6840.
No. 3 discloses that more excellent effects can be obtained when used in combination with another surfactant. Also, JP-A-63
JP-A-182488 and JP-A-63-227880 disclose a technique in which a specific fatty acid ester gives a deinked pulp having a small number of remaining inks and a high whiteness.

[0005] Subsequently, with the development of technology, the invention of a high-performance deinking agent comprising a compound to which an alkylene oxide such as ethylene oxide or propylene oxide was added to improve the whiteness of deinked pulp remarkably was made. JP-A-58-109696, JP-A-59-13
No. 0400).

However, even with the use of the deinking agents disclosed in these techniques, it was not possible to obtain high b-value deinked pulp. Further, when a conventionally known higher fatty acid or a salt thereof is used, there is a drawback that a large amount of unstripped ink is present.

[0007]

SUMMARY OF THE INVENTION The present inventors have found that, in the flotation method, the washing method, and their compromise method, the ink has excellent ink removing ability, has good operability, and particularly has a high b value and an unstripped ink. As a result of intensive research to develop a deinking agent capable of obtaining a deinked pulp with little, it was surprisingly found that the above-mentioned disadvantages could be overcome by using an ester compound of citric acid and a monohydric alcohol, The present invention has been completed.

That is, the present invention relates to citric acid and the following general formula:
An object of the present invention is to provide a deinking agent comprising an ester compound with a monohydric alcohol represented by (1) as an essential component. ROH (1) (wherein, R represents an alkyl group having 8 to 24 carbon atoms, an alkenyl group, a cycloalkyl group, or an alkylphenyl group having an alkyl group having 6 to 16 carbon atoms).

[0009] Functions required for the deinking agent include ink releasability due to a decrease in the interfacial tension between the cellulose and ink, re-adhesion prevention of the ink separated from the cellulose, ink absorption to air bubbles, and appropriate foaming properties. Four can be mentioned. The deinking agent must have these four functions in a well-balanced manner. The ester compound of the present invention is particularly excellent.

When R of the monohydric alcohol represented by the general formula (1) used in the present invention is an alkyl group, an alkenyl group or a cycloalkyl group, if the number of carbon atoms is smaller than 8, the ink collecting ability is low. Weak, high whiteness, high b-value deinked pulp cannot be obtained. If the carbon number exceeds 24, the ink releasability from cellulose decreases, so the remaining amount of unstripped ink is large, and the appearance is good. You only get bad deinked pulp. When R is an alkylphenyl group and the number of carbon atoms of the alkyl group is smaller than 6, the ink-collecting ability is weak, and high-whiteness and high-b value deinked pulp cannot be obtained. If the value exceeds 16, the releasability of the ink from the cellulose decreases, so that the remaining amount of the unremoved ink is large,
You get only deinked pulp that looks bad.

The ester compound according to the present invention can be obtained by a conventionally known method, for example, by a dehydration reaction between a monohydric alcohol represented by the above general formula (1) and citric acid.

Specific examples of the monohydric alcohol represented by the general formula (1) used as a raw material include octanol, nonal, decanol, undecanol, dodecanol,
Tridecanol, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, tetracosanol, isooctanol, 2-ethylhexanol, isononal, isodecanol, isound Decanol, isododecanol, isotridecanol, isotetradecanol, isopentadecanol, isohexadecanol, isoheptadecanol, isooctadecanol, isononadecanol, isoeicosanol, isoheneico Sanol, isodocosanol, isotetracosanol, oleyl alcohol, elaidyl alcohol, linoleyl alcohol, linolenyl alcohol, eleostearyl alcohol, ricinoyl alcohol , Cycloalkyl nonanol, cycloalkyl, octadecanol, cycloalkyl undecanol, cyclododecanol, cycloalkyl tridecanol, cycloalkyl tetradecanol,
Cyclopentadecanol, cyclohexadecanol, cycloheptadecanol, cyclooctadecanol, cyclononadecanol, cyclocosanol, octylphenol, nonylphenol, dodecylphenol, uncured or cured palm oil, tallow, fish oil Alcohol derived from a product.

Among the monohydric alcohols, R in the general formula (1) preferably has 14 to 24 carbon atoms, more preferably an alkyl group having 14 to 24 carbon atoms. .

The ester compound according to the present invention has the following structure when the esterification ratio is 100%.

[0015]

Embedded image

When the esterification ratio is less than 100%, R ₁ , R ₂ , R ₃
May be replaced by a counter ion. Also,
The ester compound according to the present invention may be an ester salt. When the ester compound according to the present invention is a partial ester, at least one of R ₁ , R ₂ , and R _{3 in} the formula (2) is an alkali metal such as hydrogen, sodium, or potassium, or an alkaline earth metal such as magnesium or calcium. , Ammonium, monoethanolamine, diethanolamine, and organic salts such as triethanolamine.

The esterification rate of the ester compound according to the present invention is preferably from 15 to 85%. More preferably, it is 30 to 75%. When the esterification ratio is lower than 15%, the ink collecting ability is weakened, so that the whiteness and the b value tend to be low. On the other hand, when the content is higher than 85%, the releasability of the ink from the cellulose becomes small, so that the remaining amount of the unreleased ink tends to increase.

The deinking agent of the present invention may be used in combination with a conventionally known deinking agent, if necessary. The compounding ratio of the product of the present invention / conventional product = 95/5 to 10/90 is preferable in terms of weight ratio, and particularly preferably 70/30 to 30/70. Conventionally known deinking agents include, for example, higher alcohol sulfates, polyoxyalkylene higher alcohol sulfates, alkylbenzene sulfonates, higher fatty acids and salts thereof, and alkylene oxide adducts of higher alcohols and alkylphenols.

The deinking agent of the present invention can provide higher quality deinked pulp when added to any step. Generally, the deinking agent is added to either or both the mixing step and the flotation step. When added separately in each step, it can be added to each of the steps of pulping, kneading, dispersing, chemical mixing, and refining, but it is added separately in the previous step (pulping step) and the subsequent step (steps after the pulping step) In this case, the dividing ratio of the deinking agent is preferably 10/90 to 90/10 (weight ratio), particularly preferably 40/60 to 60/40 (weight ratio). is there. The amount of the deinking agent added is desirably in an economical range without impairing the operability, but is preferably 0.03 to 1.0% by weight based on the used raw paper.

[0020]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 This example is an example of simultaneous addition of a deinking agent in a pulping step. After the used newspaper recovered in the city is cut into 2 x 5 cm pieces, a certain amount is placed in a tabletop disintegrator, in which water and caustic soda (based on raw materials) are 0.8% (by weight, the same applies hereinafter) and sodium silicate (based on raw materials) 2.2%, 30% hydrogen peroxide solution (based on raw material) 3.5%, various deinking agents shown in Table 1 (based on raw material) 0.5%, and pulp concentration
After disaggregation at 15% at 45 ° C for 12 minutes, the mixture was aged at 55 ° C for 120 minutes. Dehydration was performed to 23% with a high-speed dehydrator, and kneading treatment was performed with a biaxial lab kneader having a rotation speed of 300 rpm. Thereafter, water was added to dilute the pulp to a pulp concentration of 4%, and the mixture was defibrated with a desktop disintegrator for 30 seconds. Thereafter, the mixture was diluted with water to a pulp concentration of 1%, and 0.5% of calcium chloride (based on raw material) was added, followed by a flotation treatment at 30 ° C. for 10 minutes. Next, the pulp slurry after flotation was concentrated to 4% concentration with an 80-mesh wire, and diluted with water to 1% concentration to prepare a pulp sheet using a TAPPI sheet machine. The hardness of the water used was 5 ° dH, and the hardness was
CaCl ₂ and MgCl ₂ were used and adjusted so that Ca / Mg = 8/2 (molar ratio). The b value of the obtained pulp sheet was measured with a colorimeter (diffuse reflection type), and an image analyzer (× 10
In 0), the number of unstripped inks was measured. Table 1 shows the results. Here, the b value refers to the b value in the Lab color system of the Hunter color difference formula, and the relationship with the tristimulus value XYZ is as follows.

[0022]

(Equation 1)

As can be seen from this equation, the b value is a function of Y and Z, where a positive value indicates yellowness and a negative value indicates bluish intensity.

[0024]

[Table 1]

Example 2 This example is an example of the divisional addition of the deinking agent in the pulping step and the chemical mixing step. 2 x 5 used newspapers collected in the city
After chopping into pieces, a certain amount was put into a tabletop disintegrator, into which water and caustic soda (based on raw materials) 0.2%, and various deinking agents (based on raw materials) 0.1% shown in Table 2 were added. %, 50 ℃,
After fibrillation for 15 minutes, dehydrate the pulp to 18% concentration, and add 0.6% of sodium hydroxide (based on raw material), 2.2% of sodium silicate (based on raw material), 3.5% of 30% hydrogen peroxide (based on raw material), Table 2
0.2% of various deinking agents (based on raw materials) shown in Table 2 were added, the pulp concentration was adjusted to 15% with water, and mixed for 1 minute using a desktop disintegrator. 55
The ripening treatment was performed at a pulp concentration of 15% at 120 ° C. for 120 minutes. Then add water to a pulp concentration of 4%, and add 3
Disintegration treatment for 1 minute, further adding water to reduce the pulp concentration to 1%
And add 0.5% of calcium chloride (based on raw material)
A flotation treatment was performed at 30 ° C. for 10 minutes. Then
The pulp slurry after flotation was concentrated to 6% concentration with an 80 mesh wire, and then diluted to 1% concentration by adding water, and a pulp sheet was prepared using a TAPPI sheet machine. The hardness of the water used was 5 ° dH and the hardness was Ca
It was adjusted so that Ca / Mg = 8/2 (molar ratio) using Cl ₂ and MgCl ₂ . The b value of the obtained pulp sheet was measured with a colorimeter (diffuse reflection type), and an image analyzer (× 10
In 0), the number of unstripped inks was measured. Table 2 shows the results.

[0026]

[Table 2]

Example 3 This example is an example in which the deinking agent is added separately in the pulping step and the kneading step. The used newspaper collected in the market is shredded to 2 x 5 cm, and a certain amount is placed in a table disintegrator, in which water and caustic soda (based on raw materials) are 0.2%, and various deinking agents shown in Table 3 (based on raw materials) Add 0.2%, disintegrate pulp at 5%, 50 ° C for 15 minutes, dehydrate to pulp concentration of 28%, and add caustic soda (based on raw material) 0.6% and sodium silicate (based on raw material)
2.2%, 30% aqueous hydrogen peroxide (based on raw material) 3.5%, various deinking agents (based on raw material) 0.2% shown in Table 3 were added, pulp concentration was adjusted to 25% with water, and the rotation speed was 300 rpm. Kneading treatment was performed with a mold lab kneader. Thereafter, aging treatment is performed at 55 ° C. for 120 minutes at a pulp concentration of 25%, then water is added so that the pulp concentration becomes 4%, defibration treatment is performed for 3 minutes using a table disintegrator, and water is further added to reduce the pulp concentration to 1%. Diluted to 30%
A flotation treatment was performed at 10 ° C. for 10 minutes. Next, the pulp slurry after flotation is concentrated to a 6% concentration with an 80 mesh wire, and then diluted with water to 1% concentration.
A pulp sheet was prepared using a TAPPI sheet machine.
The hardness of the water used was 10 ° dH and the hardness was CaC
l ₂ and MgCl ₂ were used to adjust Ca / Mg = 8/2 (molar ratio). The b value of the obtained pulp sheet was measured with a colorimeter (diffuse reflection type), and an image analyzer (× 10
In 0), the number of unstripped inks was measured. Table 3 shows the results.

[0028]

[Table 3]

Embodiment 4 This embodiment is an example of adding a deinking agent in a pulping step and a flotation step separately. The used newspaper collected in the market is shredded to 2 x 5 cm, and a certain amount is put into a table disintegrator, in which water and caustic soda (based on raw materials) are 0.2%, and various deinking agents shown in Table 4 (based on raw materials) 0.2% was added, pulp concentration was 15%, defibration was performed at 45 ° C for 12 minutes, and ripening was performed at 55 ° C for 120 minutes. After that, dehydrate to 23% with high-speed dehydrator, and use caustic soda (based on raw material) 0.6
%, Sodium silicate (based on raw material) 2.2%, and 30% aqueous hydrogen peroxide (based on raw material) 3.5%. The pulp concentration was adjusted to 22% with water, and the mixture was mixed for 1 minute using a desktop disintegrator. After that, rotation speed 300r
The kneading process was performed using a two-axis lab kneader of pm.
Thereafter, water was added to dilute the pulp to a pulp concentration of 4%, and the mixture was defibrated with a desktop disintegrator for 30 seconds. Thereafter, 0.3% of various deinking agents (based on raw materials) shown in Table 4 were added, and the pulp concentration was adjusted to 1% with water.
And then subjected to a flotation treatment at 30 ° C. for 10 minutes. Next, the pulp slurry after flotation was
After concentrating to 4% concentration with a mesh wire, add water and add
%, And a pulp sheet was prepared using a TAPPI sheet machine. The hardness of the used water was 40 ° dH, and the hardness was CaCl ₂ or MgCl ₂ , and Ca / Mg = 8/2.
(Molar ratio). The b value of the obtained pulp sheet was measured by a colorimeter (diffuse reflection type), and the number of unstripped ink was measured by an image analyzer (× 100). Table 4 shows the results.

[0030]

[Table 4]

Claims (2)

(57) [Claims] 1. Citric acid and 1 represented by the following general formula (1)
A deinking agent containing an ester compound with a polyhydric alcohol as an essential component. ROH (1) (wherein, R represents an alkyl group having 8 to 24 carbon atoms, an alkenyl group, a cycloalkyl group, or an alkylphenyl group having an alkyl group having 6 to 16 carbon atoms.) 2. The esterification rate of the ester compound is from 15 to 85.
%.