JP5593791B2 - Foreign matter removing agent for floatator in deinking step, foreign matter removing method, and method for producing deinked pulp - Google Patents

Description

  The present invention relates to a foreign matter removing agent for a floater, a foreign matter removing method, and a deinked pulp manufacturing method in a deinking step. More specifically, the present invention relates to a foreign matter removing agent for a floatator, a foreign matter removing method, and a foreign matter amount in a deinking process capable of efficiently removing ink, ash, pitch, and the like in a process such as used paper recycling processing. The present invention relates to a method for producing a deinked pulp having a low pulp whiteness.

In recent years, the reuse of used printed paper has become a major issue from the standpoint of energy saving and resource saving. In order to collect and reuse the used printing paper, printing ink is removed by a deinking process, and pulp fibers are collected to produce deinked pulp (DIP).
Generally, the method for producing deinked pulp mainly includes a disaggregation process, an aging process, a flotation process, and a dehydration / washing process. The disaggregation step is a step of mechanically removing ink using a peeling machine, and the aging step is a step of chemically removing ink. In these peeling and aging processes, a deinking agent is generally used together with a chemical such as an alkali agent and a bleaching agent. Next, in the flotation process, bubbles are blown into the mixture of pulp and ink, and foreign matters such as ink are attached to the bubbles and floated and separated, and discharged out of the system as floss (residue after taking out the deinked pulp). . Thereafter, the obtained pulp slurry is dehydrated and washed to be adjusted to an appropriate concentration.

This flotation process is an important process that affects the quality of the product among the deinking processes. According to a flotator (flotation machine), particles having a particle diameter of 5 to 20 μm can generally be removed, but there is a problem that the removal performance for particles having a particle diameter of less than 5 μm is low.
Deinking agents used in the flotation process include inorganic flocculants such as aluminum compounds, higher alcohol or fatty acid alkylene oxide adduct surfactants, higher fatty acid agents, and crosslinked polydiallyldimethylammonium chloride. Known deinking agents (Patent Literature 1), foreign matter removing agents containing water-soluble amphoteric acrylamide polymers (Patent Literature 2), etc. are known, and are deinking methods carried out in the presence of cationic compounds, amines, etc. (For example, patent document 3) is also known.
However, although conventional deinking agents and deinking methods have improved ink peeling and removal to some extent, ink aggregation and ash removal are not sufficient.
For this reason, there has been a demand for a foreign matter removing agent and a foreign matter removing method excellent in ink removability and ash content removal for a floater in used paper recycling.

JP 2001-271284 A JP 2002-115191 A JP-A-10-158985

  The present invention provides a foreign matter removing agent for a flowator, a foreign matter removing method, and a deinked pulp manufacturing method in a deinking step capable of efficiently removing foreign matter such as ink, ash, and pitch with a flowator. Is an issue.

As a result of intensive studies to achieve the above-mentioned object, the present inventor has used a cationic homopolymer or copolymer having a structural unit derived from a specific quaternary ammonium group-containing monomer to produce a flotator. It has been found that foreign matter removal can be performed efficiently. The present invention has been completed based on such findings.
That is, the present invention provides the following (1) to (5).
(1) For a floatator in a deinking step, comprising a cationic homopolymer or copolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the following general formula (1) Foreign matter remover.

(Wherein R ¹ and R ² represent a hydrogen atom or a methyl group, R ³ and R ⁴ represent hydrogen, an alkyl group having 1 to 4 carbon atoms, a piperazine group, a piperidine group or a morpholine group, and R ⁵ represents a carbon atom. (A represents a C 1-5 alkanediyl group, and X represents a counter ion of a quaternary ammonium group.)
(2) The foreign matter removing agent for a floatator according to (1), wherein the cationic homopolymer or copolymer contains 0 to 30 mol% of a structural unit derived from an acrylamide monomer.
(3) The foreign matter removing agent for a floatator according to (1), wherein the cationic homopolymer or copolymer has a weight average molecular weight of 100,000 to 2,000,000.
(4) A foreign matter removing method, wherein the foreign matter removing agent (1) is added to a flotation step or a preceding step in deinking treatment of waste paper.
(5) A cationic homopolymer or copolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the general formula (1) is added to the pulp slurry in the deinking step. A method for producing deinked pulp.

According to the foreign matter removing agent, the foreign matter removing method, and the deinked pulp manufacturing method of the present invention, since the foreign matter such as ink, ash, and pitch can be efficiently removed with a floatator, the whiteness of the deinked pulp Can be improved, and the amount of foreign matter brought into the papermaking process can be reduced.
Moreover, since the foreign matter removing agent of the present invention has low fixability to pulp fibers and ash, it does not adversely affect the yield (recovery efficiency) of pulp fibers. Furthermore, since the waste water load can be reduced by reducing foreign matters and the ash content from waste paper can be removed, the type and particle size of the filler in the paper making process can be easily adjusted, and the paper quality can be improved.

[Foreign substance remover for waste water floatator]
(Quaternary ammonium group-containing monomer represented by general formula (1))
In the present invention, the cationic homopolymer or copolymer used in the foreign matter removing agent for a floatator has a structural unit derived from a quaternary ammonium group-containing monomer represented by the following general formula (1). This quaternary ammonium group-containing monomer imparts cationicity to the polymer or copolymer.

In the general formula (1), R ¹ and R ² represent a hydrogen atom or a methyl group, and R ³ and R ⁴ represent hydrogen, an alkyl group having 1 to 4 carbon atoms, a piperazine group, a piperidine group, or a morpholine group.
R ⁵ represents a hydrocarbon group having 1 to 22 carbon atoms, preferably a hydrocarbon group having 1 to 12 carbon atoms, more preferably a hydrocarbon group having 1 to 8 carbon atoms, and more specifically, a hydrocarbon group having 1 to 5 carbon atoms. Examples thereof include an alkyl group and a benzyl group.
A represents an alkanediyl group having 1 to 5 carbon atoms, preferably 1 to 4 carbon atoms. Specific examples of A include a methylene group, an ethylene group, a trimethylene group, a propane-1,2-diyl group, and a tetramethylene group.
X represents a counter ion of a quaternary ammonium group, and specific examples include halogen ions such as chlorine ions and iodine ions, sulfate ions, sulfite ions, perchlorate ions, phosphate ions, borate ions, or p- Examples include anions of organic acid salts such as toluenesulfonate ions.

The quaternary ammonium group-containing monomer represented by the general formula (1) is obtained by reacting a corresponding tertiary amine with a quaternizing agent such as methyl chloride, benzyl chloride, or methyl sulfate by a known method. be able to. Specific examples thereof include a methyl chloride quaternized product of dialkylaminoalkanediyl (meth) acrylamide and a benzyl chloride quaternized product.
Among them, a quaternary ammonium group-containing monomer represented by the following general formula (2) is preferable from the viewpoint of foreign matter removal performance.

In the general formula (2), R ² represents a hydrogen atom or a methyl group, R ³ and R ⁴ represent a methyl group or an ethyl group, R ⁵ represents an alkyl group having 1 to 3 carbon atoms, and n represents 2 or 3.
Specific examples thereof include dimethylaminopropylacrylamide (DMAPAA) methyl chloride quaternized product (acrylamidopropyltrimethylammonium chloride), dimethylaminoethylacrylamide methyl chloride quaternized product, dimethylaminopropyl methacrylamide methyl chloride quaternized product, Examples include methyl chloride quaternized product of dimethylaminoethyl methacrylamide.

(Cationic copolymer)
In the present invention, when a cationic copolymer is used, the copolymerized monomer with the quaternary ammonium group-containing monomer represented by the general formula (1) is preferably a substituted or unsubstituted acrylamide and / or methacrylamide. Can be mentioned. The substituent is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably 1 to 5 carbon atoms, which is substituted on the nitrogen atom of the amide.
Specific examples of the copolymerization monomer include acrylamide, N-methylacrylamide, N-ethylacrylamide, N-cyclopropylacrylamide, N-isopropylacrylamide, methacrylamide, N-methylmethacrylamide, N-cyclopropylmethacrylamide, N -Isopropylmethacrylamide, N, N-dimethylacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-isopropylacrylamide, N-methyl-Nn-propylacrylamide, N, N-diethylacrylamide, etc. It is done. Among these, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide and the like are more preferable from the viewpoint of functionality.
The cationic copolymer preferably contains 30 mol% or less, more preferably 20 mol% or less, more preferably 10 mol% or less, and still more preferably 5 mol% or less of the structural unit derived from the copolymer monomer.

(Production of cationic homopolymer or copolymer)
The production of a cationic homopolymer or copolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the general formula (1) includes a quaternary ammonium group represented by the general formula (1). The monomers can be carried out using known polymerization methods in an aqueous medium such as water containing a water-miscible solvent, for example, an alcohol such as isopropanol, optionally together with the copolymerization monomer.
The polymerization is preferably performed by dropping the monomer into an aqueous medium containing a polymerization initiator.
As the polymerization initiator, a small amount of a radical forming substance such as potassium or ammonium peroxodisulfate, t-butyl hydroperoxide, azobis (isobutyronitrile) and the like can be used.
Although polymerization temperature is not specifically limited, 5-100 degreeC is preferable according to the polymerization initiator to be used, and 10-90 degreeC is more preferable. In this way, a polymer solution of a polymer or copolymer having a polymer content (solid content concentration) of preferably 5 to 60% by weight, more preferably 10 to 50% by weight can be obtained.
The weight average molecular weight of the polymer or copolymer is preferably 100,000 to 2,000,000, and more preferably 150,000 to 1,000,000 from the viewpoints of foreign matter removal effect and pulp yield. The weight average molecular weight can be measured by a known method using, for example, a light scattering photometer.

[Foreign matter removal method]
In the foreign matter removing method of the present invention, a foreign matter removing agent containing a cationic homopolymer or copolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the general formula (1) is used. It is characterized by being added to the flotation step in the deinking process or a previous step thereof, whereby pulp fibers and foreign matters such as ink, ash, and pitch can be efficiently separated and removed.

(Application to flotation process in deinking process)
In the deinking treatment of used paper, the foreign matter removing agent containing the cationic homopolymer or copolymer is added to the flotation step or the previous step to perform the flotation treatment.
The raw material for the deinked pulp manufacturing process is generally in a state where SS (suspended substance) showing strong anionicity is dispersed. For the SS having such strong anionicity, the foreign substance removing agent of the present invention is a cationic homopolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the general formula (1) or Since the copolymer is contained, the particle size of the colloidal SS can be grown to a size that can be processed by a flowmeter by the charge neutralization action and the coagulation action, thereby obtaining the excellent effect of the present invention. It is thought that you can. Further, since the foreign matter removing agent of the present invention has low fixability to pulp fibers and ash, it can efficiently discharge only foreign matter components without affecting the yield of pulp fibers.

Although there is no restriction | limiting in particular in the addition method of a foreign material removal agent, Adding as aqueous solution is preferable.
The foreign matter removing agent can be added not only to the floatator but also to any preceding step, for example, a pulper, a kneader, a tower, a dehydrator between the pulper and the kneader, or a pipe connecting them.
Here, as the flowator in the present invention, not only the primary flowator mainly used for deinking, but also the secondary flowator for treating the floss discharged from the primary flowator and the cleaning process after the flowator are discharged. It also includes a floatator installed in a recovery / reuse water system that treats wastewater.

Although there is no restriction | limiting in particular in the addition amount of a foreign material removal agent, Preferably it is 0.5-100 mg / L with respect to the process raw | natural water in the said cationic homopolymer or copolymer in a floater process, More preferably, 1- It is desirable to add 80 mg / L, more preferably 5 to 60 mg / L. When the added amount is within the above range, the foreign matter removing effect is sufficient, and there is no inconvenience that the pulp fiber is excessively transferred to the floss and the pulp yield is lowered.
When the foreign matter removing agent is added, the added amount of the foreign matter removing agent can be adjusted by measuring the whiteness and ash content of the resulting deinked pulp.
The foreign matter removing method of the present invention is excellent in the effect of aggregating already peeled ink, ash, pitch, etc. and separating from the pulp fiber, but further known organic deinking agents (surfactant) Agent) and auxiliary agents such as foaming agents can be added together.

[Method for producing deinked pulp]
The deinked pulp production method of the present invention comprises a cationic homopolymer or copolymer having a structural unit derived from a quaternary ammonium group-containing monomer represented by the following general formula (1) in the pulp slurry of the deinking step. It is characterized by adding a polymer.

（式中、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ａ、及びＸは前記と同様である。）

(In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , A, and X are the same as described above.)

(Specific production example of deinked pulp)
Production of deinked pulp in the present invention can be carried out in the same manner as conventionally known deinked pulp production methods. For example, first, waste paper is added to water containing alkali such as sodium hydroxide and sodium silicate, the used paper is disaggregated with a pulper (pulp disaggregation device) to make a pulp slurry, and then a pulp slurry and a deinking agent (for example, a kneader) Nonionic surfactant) is kneaded and the printing ink is peeled off from the pulp. Next, the mixture is bleached with a tower to which hydrogen peroxide has been added, and foreign matters such as ink, ash, and pitch are floated and separated by a flotator (flotation machine) and discharged out of the system as floss. Thereafter, the pulp slurry can be deinked pulp (DIP) by removing water with an extractor or the like and further resuspending the pulp in water and then washing the pulp with a filter. The foreign matter removing agent of the present invention may be added to the flotator or may be added at the previous stage, but is preferably added immediately before the flotator.
In the flotator, bubbles are blown into the pulp slurry, and foreign matters such as ink are attached to the bubbles to float and separate from the pulp. In this case, a known organic deinking agent can also be added.
In the prior art, even if flotation is performed in this state, foreign matter such as peeled ink is kept in a dispersed state and difficult to separate, but the cationic homopolymer or copolymer according to the present invention is added. When flotation is performed, foreign matter such as separated ink, pitch, and ash aggregates to form a flock, which adheres to bubbles and floats and is separated. Thus, when the removal rate of foreign matter such as ink, ash, and pitch of the pulp slurry is improved, the whiteness of the paper product produced by blending the obtained deinked pulp is improved, and the defects due to foreign matter, This leads to quality improvements such as reduction, yield, freeness improvement, and paper strength improvement, productivity improvement, and operability improvement. In addition, these improvements make it possible to increase the blending ratio of deinked pulp, and to reduce the pulp raw material cost in the manufacturing cost.

  The deinked pulp from which foreign matters such as ink, pitch and ash are removed in this way is suitably used as a waste paper material for producing newspaper, magazine paper, OA paper, medium-size printing paper, flyer paper, cardboard paper, etc. can do.

EXAMPLES Next, although an Example demonstrates this invention still in detail, this invention is not limited at all by these examples.
In addition, the measurement of the amount of froth, the suspended solid content concentration of a slurry, pitch concentration, and the whiteness of a pulp sheet was performed with the following method.
(1) Floss amount The pulp slurry was treated with a floatator to float and separate foreign substances such as ink, and the amount discharged as floss out of the system was measured.
(2) Suspension solid content concentration of slurry The suspension solid content concentration of the pulp slurry after the flotation treatment was measured according to JIS K 0102.
(3) Pitch concentration of the slurry The pulp slurry collected after the flotation treatment is evaporated to dryness, soxhlet extraction is performed using dichloromethane, and the concentration of pitch (adhesive or synthetic resin mixed in the pulp) is determined from the extracted weight. Calculated.
(4) Whiteness of pulp sheet Using a tapi sheet machine, two pulp sheets were prepared in accordance with JIS P 8209, and the obtained pulp sheet was in accordance with JIS P 8123 using a hunter whiteness meter. The whiteness was measured. The whiteness was measured at five points for each sheet, and the average value was obtained.
The whiteness is preferably 32 or more.

Production Example 1
Using dimethylaminopropylacrylamide methyl chloride quaternary salt (manufactured by Kojin Co., Ltd., DMAPAA-Q, 79% aqueous solution, viscosity 80-90 cps (25 ° C.)) and dimethylacrylamide (manufactured by Wako Pure Chemical Industries, Ltd., activated alumina) And used after removing the polymerization inhibitor) at 25 ° C., and a dimethylaminopropylacrylamide methyl chloride quaternary salt: dimethylacrylamide (molar ratio) = 99: 1 copolymer (weight average molecular weight: 200,000). Obtained.
The results are shown in Table 1.
Production Example 2
Diallyldimethylammonium chloride (60% aqueous solution) and dimethylacrylamide (manufactured by Wako Pure Chemical Industries, Ltd., used after removing the polymerization inhibitor using activated alumina) are reacted at 25 ° C., and diallyldimethylammonium chloride: dimethylacrylamide A copolymer (molar ratio) = 30: 70 (weight average molecular weight: 3 million) was obtained.
The results are shown in Table 1.

Production Example 3
11 g of demineralized water was added to 2.36 g of hexamethylene diamine, and 70.5 g (effective amount 28.2 g) of a 40 wt% dimethylamine aqueous solution was further added to dissolve hexamethylene diamine. Epichlorohydrin 64.8g was put into the dropping funnel and it was made to react by dripping over 6 hours to the obtained hexamethylenediamine solution, keeping at 17-18 degreeC.
The obtained reaction solution was heated to 50 ° C. and held for 3 hours, and then heated to 90 ° C., 2.4 mL of 33 wt% sodium hydroxide aqueous solution was added, and further maintained at 90 ° C. for 3 hours. Cooled to 30 ° C. Subsequently, 6N hydrochloric acid was added to adjust the pH of the aqueous solution to 5.5 to obtain an epichlorohydrin-dimethylamine condensate (weight average molecular weight: 250,000).
The results are shown in Table 1.

Examples 1 and 2
In the waste paper pulp manufacturing process in which deinking processing is performed using newspapers and flyers as raw paper raw materials, raw water of a secondary flowator (a flowmeter for froth treatment of a primary flowator) was used as a sample.
The sample 5L and the copolymer of (dimethylaminopropylacrylamide methyl chloride quaternary salt / dimethylacrylamide) obtained in Production Example 1 were added in the amounts shown in Table 2, and a small MT flowator (IHI Mechanical System Co., Ltd.) was added. And stirred for 30 seconds.
Next, the amount of air was set to 3 L / min, and a 4 minute flotation process was performed.
The results are shown in Table 2.

Comparative Examples 1-3
In Example 1, the same operation as in Example 1 was performed except that the copolymer of (diallyldimethylammonium chloride / dimethylacrylamide) obtained in Production Example 2 was added in the amount shown in Table 2 as a foreign substance removing agent. went. The results are shown in Table 2.
Comparative Examples 4-5
In Example 1, the same operation as in Example 1 was performed, except that the epichlorohydrin-dimethylamine condensate obtained in Production Example 3 was added in the amount shown in Table 2 as a foreign substance removing agent. The results are shown in Table 2.

In Examples 1 and 2, pulp sheets with low pitch concentration and high whiteness in the slurry were obtained. On the other hand, in Comparative Example 1 (no foreign substance removing agent added) and Comparative Examples 2 to 3 (DADMAC type copolymer added), the pitch concentration in the slurry was high and the whiteness was low.
Further, in Comparative Examples 4 and 5 (with epichlorohydrin / dimethylamine condensate added), although the results of whiteness were almost the same as those of the examples, the pitch concentration in the slurry reached the results of the examples. There wasn't.

  According to the foreign matter removing agent, foreign matter removing method, and deinked pulp manufacturing method of the present invention, colloidal particles are efficiently agglomerated while minimizing a decrease in the yield of pulp fibers, and ink, ash content in a flowmeter, Foreign matter such as pitch can be removed efficiently. The foreign matter removing agent, the foreign matter removing method, and the deinked pulp manufacturing method of the present invention are also effective in used paper processing under a high pH environment or a high salt environment.

Claims (4)

A foreign matter removing agent for flotation in deinking process comprising a cationic copolymer having a constitutional unit derived from the quaternary ammonium group-containing monomer represented by the following general formula (1),
The copolymerizable monomer that is copolymerized with the quaternary ammonium group-containing monomer represented by the general formula (1) in the copolymer is an unsubstituted or linear or branched alkyl group having 1 to 5 carbon atoms. Substituted acrylamide and / or methacrylamide;
The copolymer is a foreign matter removing agent for a floatator, containing 30 mol% or less of the structural unit derived from the acrylamide and / or methacrylamide.

(Wherein R ¹ and R ² represent a hydrogen atom or a methyl group, R ³ and R ⁴ represent hydrogen, an alkyl group having 1 to 4 carbon atoms, a piperazine group, a piperidine group or a morpholine group, and R ⁵ represents a carbon atom. (A represents a C 1-5 alkanediyl group, and X represents a counter ion of a quaternary ammonium group.) The weight average molecular weight of the cationic copolymer is 100,000 2,000,000 flotation for foreign matter removal agent according to claim 1.   A foreign matter removing method, wherein the foreign matter removing agent according to claim 1 or 2 is added to a flotation step or a preceding step in a deinking process of waste paper. To the pulp slurry during the deinking process, a process for the preparation of a deinked pulp of adding a cationic copolymer having a constitutional unit derived from the quaternary ammonium group-containing monomer represented by the following general formula (1),
The copolymerizable monomer that is copolymerized with the quaternary ammonium group-containing monomer represented by the general formula (1) in the copolymer is an unsubstituted or linear or branched alkyl group having 1 to 5 carbon atoms. Substituted acrylamide and / or methacrylamide;
The method for producing deinked pulp, wherein the copolymer contains 30 mol% or less of the structural unit derived from the acrylamide and / or methacrylamide.

(Wherein R ¹ and R ² represent a hydrogen atom or a methyl group, R ³ and R ⁴ represent hydrogen, an alkyl group having 1 to 4 carbon atoms, a piperazine group, a piperidine group or a morpholine group, and R ⁵ represents a carbon atom. (A represents a C 1-5 alkanediyl group, and X represents a counter ion of a quaternary ammonium group.)