JP4824376B2 - Method for producing deinked pulp derived from used newspaper - Google Patents

Description

  The present invention relates to a method for producing deinked pulp derived from newspaper wastepaper, and a finely divided or dissolved silicate filler contained in a large amount of deinked pulp derived from newspaper wastepaper is re-solubilized to obtain a filler derived from newspaper wastepaper. It is possible to efficiently improve the yield of ash containing ash, and to achieve both reduction of production cost and reduction of environmental load.

Conventionally, in order to collect and reuse waste paper, it is necessary to remove unnecessary components such as ink from waste paper from pulp slurry using chemicals such as deinking agents and bleaching agents, and to collect as high purity pulp fibers as possible. There is. For this reason, deinked pulp basically separates old paper with a pulper, removes foreign matter such as adhesive tape with a screen, and blows air bubbles into pulp slurry diluted with water with a floatator to separate the ink from the pulp. Thereafter, it is produced by dehydrating and concentrating again and bleaching.
Therefore, since components other than pulp fibers are eliminated as foreign matter as much as possible, the waste paper-derived filler or ash occupying about 5 to 40% by weight is useful for improving the quality of the paper, but the deinking process. A considerable amount of pulp drops into the water through the process of washing and dehydration, etc., and some of it is recovered and added to the papermaking system. It is the actual situation.

Silicate compounds are widely used as inorganic fine particles used as fillers. For example, white carbon added to newspaper base paper is a typical example.
In general, the deinking process is a strong alkali that uses sodium hydroxide, sodium silicate, etc. to promote decomposition of resin components added to paper, swelling of pulp fibers, or bleaching with hydrogen peroxide. However, when exposed to such conditions, even water-insoluble silicate compounds are partly decomposed and changed to water-soluble sodium silicate, resulting in atomized or dissolved state. As a result, the possibility of yielding in pulp and sending it to the papermaking system becomes extremely low.
Thus, in recent years, from the viewpoint of environmental conservation and effective use of resources, it has been required to increase the yield of ash containing fillers and reduce the amount of wastewater and waste, but this is not easy to achieve.

  Patent Document 1 discloses a surfactant (specifying a surface tension under a dynamic condition or a static condition for the purpose of maintaining a high yield of ash contained in raw material waste paper while maintaining ink removal efficiency ( In Examples, a method for producing regenerated pulp is disclosed in which a higher alcohol-based or nonionic surfactant or the like (see paragraphs 32-33) is added before the flotation step.

  Patent Document 2 has a weight average molecular weight of 500,000 to 5,000,000, acrylamide 40 to 99.3 mol%, cationic monomer 0.5 to 50 mol%, anionic monomer 0.2 to 10 mol. % Waste paper that effectively removes foreign matter such as pitch, ash containing filler (paragraph 2), ink, etc. A foreign matter removing agent for a deinking process floatator is disclosed (claims 1 to 4).

  Patent Document 3 discloses one or more compounds selected from a cationic surfactant, a water-soluble cationic organic polymer, and a water-soluble amphoteric organic polymer, or a water-soluble anionic organic polymer and a water-soluble nonionic organic. An auxiliary agent for removing hot melt adhesive resin from waste paper (for example, magazine waste paper) by further using at least one selected from polymers is disclosed (claims 1 to 4).

  Patent Document 4 discloses a polymerized cationic polymer and / or a polycondensation-based cationic substance (for example, 2- ( Methacryloyloxy) ethyltrimethylammonium chloride, etc.) (see paragraph 17), the turbidity of recycled paper pulp is reduced, the amount of chemicals added to the papermaking raw material is reduced, and as a result Waste paper recycled pulp intended to suppress the occurrence of dirt and defects, or paper made using the pulp is disclosed (see claims 1 to 5).

  In Patent Document 5, bisquaternary ammonium (meth) acrylamide and aminoalkyl (meth) acrylate or aminoalkyl (meth) acrylamide cationic monomer are added to (meth) acrylamide and, if necessary, (meth) acrylic. By using a paper additive containing a water-soluble copolymer obtained by copolymerizing an unsaturated carboxylic acid such as acid, itaconic acid, maleic acid or a salt thereof (page 3) as an active ingredient, in a neutral or alkaline region. It is disclosed that the yield of the sizing agent and filler is improved in the paper making (Patents, page 2, lower left column to lower right column).

In Patent Document 6, a waste paper pulp having a high ash content and a high whiteness is produced and condensed with respect to the waste paper pulp in a washing or / and dehydration process before the completion of the waste paper pulp for the purpose of reducing sludge ash and filler. It is disclosed that an agent is added (see claim 1).
Examples of the coagulant include aluminum sulfate, water-soluble cationic polymers such as polyacrylamide and polydadomac, and the like (see claim 4, paragraph 18). An example of using the water-soluble cationic polymer in a pulp slurry or washing shower water before dehydration is described in the process for producing waste paper pulp using (see paragraph 22 and Table 1).

In Patent Document 7, for the same purpose as Document 6, a coagulant is added to waste paper pulp before being fed to the raw material adjusting process of the paper machine (which is the final stage of the waste paper pulp manufacturing process). (See claim 1, step 10).
Examples of the coagulant include aluminum sulfate or water-soluble cationic polymers such as polyacrylamide and polydadomac (see claim 3, paragraph 12). In Examples 1 to 7, high-ash printed waste paper The water-soluble cationic polymer is used on the downstream side of the flow chest where the waste paper pulp is fed from the waste paper pulp tank or on the upstream side of the feed pump, using the waste paper pulp deinked with An example is given (see paragraph 23, table 1).

JP 2003-293277 A JP 2002-115191 A JP 2001-159084 A JP 2005-179831 A JP-A-62-85100 JP 2005-209779 A JP 2005-206978 A

Patent Document 5 is not related to the production of deinked pulp, but is intended to improve the yield of sizing agents and the like in a general papermaking process. The technical field and purpose are completely different from those of the present invention for improving the yield.
Patent Document 2 is intended to remove foreign matters such as pitch, ash, and ink in the production of deinked pulp, and Patent Document 3 is also a special technique for removing hot-melt adhesive resin. The object of the present invention is to improve the yield of the filler in the process in the first place (that is, the prior literature is removal of the filler and the present invention is recovery).
Patent Document 4 is intended to reduce the turbidity of recycled paper recycled pulp in the papermaking process after the deinking process, and the present invention is intended to improve the yield of the filler in the deinking process. Its purpose and challenges are different.

On the other hand, Patent Document 1 is intended to add a surfactant having specific parameters before the flotation step to maintain a high yield of ash contained in the raw waste paper. However, there are insufficient points to improve the yield of ash containing filler.
In addition, as described above, Patent Document 2 adds a water-soluble amphoteric acrylamide polymer to a flotation step or a previous step for the purpose of removing pitch, ash, ink, and the like. As shown in FIG. 2, when the polymer is actually added during the flotation process, it becomes a slurry in which strong sticky bubbles are involved, and the ink cannot be separated satisfactorily, which hinders the deinking process itself.

Further, Patent Documents 6 to 7 add a coagulant to the washing or / and dewatering process before the completion of the waste paper pulp or before feeding to the raw material adjustment process of the paper machine. As shown in the examples, the coagulant is added for pulp made of high ash printed waste paper, and the filler used for the high ash printed waste paper is generally calcium carbonate, kaolin, talc, etc. Is relatively stable even under alkaline conditions.
On the other hand, the filler used in newspaper base is still a silicic acid compound called white carbon, and the main raw material is silica, so the particles easily disintegrate under alkaline conditions and eventually become water-soluble. It turns into sodium silicate salt.
Therefore, even if the methods of Patent Documents 6 to 7 are directly applied to the pulp slurry derived from used newspaper, it is not easy to recover the ash containing filler with a good yield.
Moreover, the newspaper base paper has a very high recycling rate compared to other printing papers, and it is processed under strong alkaline conditions and high temperatures to make it reusable. Maintaining high ash is a difficult factor.

  This invention makes it a technical subject to collect | recover the ash content containing a filler with good yield from the pulp slurry derived from used newspaper, and to utilize this effectively.

In general, the filler or ash contained in the waste paper has all charged states, and has properties such as higher specific gravity and lower hydrophobicity and less adhesion to bubbles than ink.
Based on this knowledge, the present applicant has previously proposed an appropriate size in Japanese Patent Application No. 2004-221108 (hereinafter referred to as “prior application technology”) after a flotation process in which ink is attached to bubbles and separated by floating. A method for producing deinked pulp that allows a water-soluble amphoteric copolymer having a molecular weight of 1 to act to efficiently agglomerate a filler having any charged state on a pulp fiber and effectively improve the yield of ash containing the filler. Proposed.

The inventors further improved the prior application technique, and in particular, for the purpose of improving the suitability for silicate-based fillers abundantly contained in deinked pulp derived from newspaper waste paper, As shown in the water-soluble amphoteric copolymer of the prior application technique, the silicate-based filler that has been atomized or dissolved is made to hardly dissolve again by the action of a polyvalent metal compound or the like. When a cationic monomer , or in addition to this, an anionic monomer as a constituent component and a predetermined water-soluble amphoteric or cationic polyacrylamide copolymer using a crosslinking monomer or a chain transfer agent are allowed to act, The present invention was completed by finding that the yield of ash containing filler can be more effectively improved by re-solubilization of the acid-based filler and its aggregation.

That is, the present invention 1 is a deinking pulp manufacturing method in which an additive for manufacturing deinking pulp is added to a pulp slurry containing a silicate-based filler derived from newspaper waste paper during deinking treatment.
The additive for producing deinked pulp is a combination of (A) a substance that makes water-soluble silicate hardly soluble and (B) a water-soluble polymer substance,
(A) At least one kind selected from inorganic acids, C _{1 to} C ₄ organic acids, polyvalent metal salts, polyvalent metal oxides, polyvalent metal hydroxides, and polyvalent metal salt condensates as the poorly soluble substance And
(B) The water-soluble polymer substance comprises (a) (meth) acrylamide and (b) a cationic monomer as constituents, or (a) (meth) acrylamide and (b) a cationic monomer, (c) A water-soluble ionic polyacrylamide copolymer polymerized using (a ) an anionic monomer as a constituent, and (d) a crosslinkable monomer and / or (e) a chain transfer agent,
Production of deinked pulp characterized in that by adding the additive before the dehydration process of the pulp slurry from which the ink has been separated in the flotation process, it is possible to improve the yield of ash containing fillers from used newspaper Is the method.

  The present invention 2 is the present invention 1, wherein (A) the hardly soluble substance is at least one of a polyvalent metal oxide, a polyvalent metal hydroxide, and a polyvalent metal salt condensate, and (B) a water-soluble polymer. A method for producing deinked pulp, wherein the substance is an amphoteric polymer substance.

The present invention 3 is have you to the present invention 1 or 2, cationic monomer (b) is, primary to tertiary amino group-containing (meth) acrylamide, primary to tertiary amino group-containing (meth) acrylate, quaternary ammonium A deinked pulp manufacturing method characterized in that it is at least one of a base-containing (meth) acrylamide, a quaternary ammonium base-containing (meth) acrylate, and a diallyldialkylammonium halide.

Invention 4 is characterized in that in any one of Inventions 1 to 3 , the anionic monomer (c) is at least one of α, β-unsaturated carboxylic acids and α, β-unsaturated sulfonic acids. And a method for producing deinked pulp.

(1) Conventionally, silicate fillers that are abundant in deinked pulp derived from used newspapers are easy to atomize or dissolve under strong alkaline conditions and have a low possibility of yielding on pulp fibers.
In contrast to this, the present invention further improves the prior application technique, and in addition to the water-soluble amphoteric copolymer of the prior application technique, in addition to the polyacrylamide-based water-soluble amphoteric or cationic polymer substance (B). In addition, a substance (A) that makes the silicate-based filler abundantly contained in deinked pulp derived from newspaper waste paper is newly used in combination.
That is, in the present invention, the silicate filler that has been atomized or dissolved under strong alkaline conditions is re-solubilized with the component (A), and the hardly soluble product is smoothly aggregated with the component (B). Ashes can be recovered with better yield than the prior application technology. For this reason, the operability (usability) of the operator in the paper making process after the deinking process is improved.
In addition, although the said patent document 4 is common with this invention by the point which adds a chemical | medical agent after a flotation process, as mentioned above, the said reference 4 is the turbidity of the used paper recycled pulp in the papermaking process after a deinking process. The purpose and problem are different from those of the present invention which aims to improve the yield of the filler during the deinking process in order to reduce it.
Moreover, although the said patent documents 6-7 are close to this invention in the point which adds a chemical | medical agent before sending to the washing | cleaning or / and dehydration process of a used paper pulp completion process, or the raw material adjustment process of a paper machine, As shown in the examples, these are intended for pulp made of high ash printed waste paper using fillers such as calcium carbonate, kaolin, and talc, which are relatively stable even under alkaline conditions. Even if it is applied as it is to a pulp slurry derived from used newspaper mainly using a silicate-based filler to be finely divided, sufficient recovery of the ash containing the filler is not easy.

(2) As described above, the silicate filler contained in a large amount of deinked pulp derived from newspaper waste paper can be effectively re-solubilized with component (A), and this re-solubilized action and component (B) The yield efficiency of the ash containing filler can be improved smoothly by the coagulation action of the hardly soluble material.
Therefore, the production method of the present invention is highly suitable for deinked pulp derived from used newspaper.
In addition, when newspaper paper is made using the deinked pulp of the present invention, the deinked pulp has a high yield of filler (particularly silicate-based filler). The replenishment amount can be effectively reduced.
By the way, ash containing filler with high specific gravity will fall into the water after the dehydration process, so the deinking pulp additive of the present invention is added after the flotation process and before the dehydration process. There is a need to.

In the production of deinked pulp in which an additive for producing deinked pulp is added to a pulp slurry derived from newspaper wastepaper, the present invention provides a substance (A) that hardly dissolves water-soluble silicate and a highly water-soluble polyacrylamide. This is a method for producing deinked pulp in which a mixture of molecular substances (B) is added as an additive after the flotation step and before the dehydration step.
The above-mentioned waste paper-derived pulp slurry is a pulp slurry containing a portion of newspaper waste paper and containing a large amount of a silicate filler, and therefore is not limited to pulp slurry containing only newspaper waste paper, It is a concept including pulp slurry containing other types of recycled paper. In short, in the present invention for the purpose of efficiently recovering a silicate-based filler that is easily atomized or dissolved under strong alkaline conditions, the pulp slurry to be applied is centered on the waste paper-derived content. The pulp slurry contains a large amount of such a silicate filler.
The hardly soluble substance (A) is at least one selected from inorganic acids, C ₁ -C ₄ organic acids, polyvalent metal salts, polyvalent metal oxides, polyvalent metal hydroxides, and polyvalent metal salt condensates. The water-soluble polymer substance (B) is at least one selected from polyacrylamide-based water-soluble amphoteric polymer substances and water-soluble cationic polymer substances .

One of the poorly solubilized substances (A) of the additive for deinking pulp of the present invention is a polyvalent compound having a binding function between an acidifying agent that adjusts the strong alkaline condition in the deinking process to the acidic side and silicate. It is a concept that includes both metallic compounds.
The acidifying agent refers to inorganic acids and organic acids. The inorganic acids are any acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, borofluoric acid, sulfamic acid, polyphosphoric acid and the like. In particular, the organic acids are C _{1 to} C ₄ organic acids, and formic acid, acetic acid, propionic acid, butyric acid, maleic acid, fumaric acid, lactic acid and the like are specific examples. Therefore, Patent Documents 1 and 3 disclose higher fatty acid deinking agents such as stearic acid and palmitic acid, and antifoaming agents such as oleic acid, but these higher fatty acids are excluded from the present invention. .
The polyvalent metal compound refers to a polyvalent metal salt, a polyvalent metal oxide, a polyvalent metal hydroxide, or a polyvalent metal salt condensate. Typical examples of the polyvalent metal are calcium, aluminum, iron, magnesium, barium and the like from the viewpoint of practical use. Specific examples of polyvalent metal compounds include aluminum chloride, calcium chloride, aluminum sulfate, ferric sulfate, barium sulfate, calcium oxide, magnesium oxide, barium oxide, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, polychlorinated Examples thereof include aluminum, polyferric sulfate, and aluminate.
As the component (A), a polyvalent metal compound is more effective than an acidifying agent, and the polyvalent metal compound exhibits acidity at the same time (that is, also functions as an acidifying agent). The compound is more effective.
As the hardly soluble substance (A), as shown in the present invention 2, many compounds exhibiting acidity belong, and polyvalent metal oxides such as calcium oxide and polyvalent metals such as magnesium hydroxide which are effective even in relatively small amounts. Hydroxides or polyvalent metal salt condensates such as polyaluminum chloride and polyferric sulfate are preferred.
The component (A) can be used alone or in combination, and the amount added to the pulp slurry is arbitrary, and there is no particular limitation.

The other additive for deinking pulp of the present invention is a water-soluble polymer substance (B), which is selected from a water-soluble amphoteric polymer substance and a water-soluble cationic polymer substance . These macromolecular substances include both homopolymers or copolymers. Further, it means a product obtained by polymerization reaction or polycondensation reaction.
The water-soluble polymer substance is a water-soluble ionic polyacrylamide (PAM) copolymer. However, any water-soluble polymer other than PAM-based materials such as polydiallyldimethylammonium chloride (abbreviated as PDADMAC), polyamide polyamine-epichlorohydrin resin (abbreviated as PAE), polyethyleneimine, polyvinylamine, polyacrylic acid, polymaleic acid, etc. As in the case of the water-soluble ionic PAM copolymer, it is effective in terms of aggregating action of the hardly soluble material.
As the water-soluble ionic PAM copolymer, as shown in the present invention 1, (a) (meth) acrylamide, (b) a cationic monomer, and (c) an anionic monomer are constituent components. A water-soluble amphoteric copolymer or a water-soluble cationic copolymer having the component (a) and the component (b) as constituents may be mentioned, and the water-soluble anionic copolymer is excluded from the present invention .
The (meth) acrylamide (a) means acrylamide (abbreviated as AM) or methacrylamide.

The cationic monomer (b), which is a constituent unit of the water-soluble amphoteric PAM copolymer, includes a primary to tertiary amino group-containing (meth) acrylamide, a primary to tertiary amino group-containing (meth) acrylate, and a quaternary ammonium base. Containing (meth) acrylamide, quaternary ammonium base-containing (meth) acrylate, diallyldialkylammonium halide (see Invention 4), and having one or more cationic groups in the molecule, for example, 4 A representative example of the quaternary ammonium base-containing monomer is a compound represented by the following general formula (1).
[CH ₂ = C (R ₁ ) —CO—A—R ₂ —N ⁺ (R ₃ ) (R ₄ ) (R ₅ )] X ⁻ (1)
(In the formula (1), R ₁ is H or CH ₃ ; R ₂ is a C ₁ -C ₃ alkylene group; R ₃ , R ₄ , R ₅ are H, C ₁ -C ₃ alkyl group, benzyl group, CH ₂ CH (OH) CH ₂ N ⁺ (CH ₃ ) ₃ X ⁻ , which may be the same or different; A is O or NH; X is an anion such as halogen or alkyl sulfate)

The primary or secondary amino group-containing (meth) acrylamide is a primary amino group-containing (meth) acrylamide such as aminoethyl (meth) acrylamide, or methylaminoethyl (meth) acrylamide, ethylaminoethyl (meth) acrylamide. Secondary amino group-containing (meth) acrylamides such as t-butylaminoethyl (meth) acrylamide.
The tertiary amino group-containing (meth) acrylamide is dimethylaminoethyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide (dimethylaminopropyl acrylamide is abbreviated as DMAPAA), diethylaminoethyl (meth) acrylamide, diethylaminopropyl ( A representative example is dialkylaminoalkyl (meth) acrylamide such as (meth) acrylamide.
The primary or secondary amino group-containing (meth) acrylate is a primary amino group-containing (meth) acrylate such as aminoethyl (meth) acrylate, or methylaminoethyl (meth) acrylate or ethylaminoethyl (meth) acrylate. Secondary amino group-containing (meth) acrylates such as t-butylaminoethyl (meth) acrylate.
The tertiary amino group-containing (meth) acrylate is a dialkylaminoalkyl (meth) acrylate such as dimethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminoethyl (meth) acrylate, or diethylaminopropyl (meth) acrylate. ) Acrylate is a representative example.

The quaternary ammonium base-containing (meth) acrylamide or the quaternary ammonium base-containing (meth) acrylate is a tertiary ammonium base-containing (meth) acrylamide or a tertiary ammonium base-containing (meth) acrylate with methyl chloride, benzyl chloride, Mono-quaternary base-containing monomer using quaternizing agents such as methyl sulfate and epichlorohydrin, such as acrylamidopropyltrimethylammonium chloride (abbreviated as DMAPAA-Q), acrylamidopropylbenzyldimethylammonium chloride, methacryloyloxyethyldimethylbenzylammonium chloride (Abbreviated as DM-BQ), acryloyloxyethyldimethylbenzylammonium chloride, (meth) acryloylaminoethyltrimethylammonium chloride, (meth) acryloylaminoethyltriethylan Niumukurorido, (meth) acryloyloxyethyl trimethyl ammonium chloride, and (meth) acryloyloxyethyl triethylammonium chloride.
The cationic monomer (b) is preferably a bis-quaternary base-containing monomer having two quaternary ammonium bases in the molecule from the viewpoint of increasing the cohesive strength of the amphoteric copolymer filler. Examples thereof include bisquaternary base-containing (meth) acrylamide having two quaternary ammonium bases, or bisquaternary base-containing (meth) acrylate. Examples of bis quaternary base-containing (meth) acrylamide include bis quaternary base-containing (meth) acrylamide (DMAPAA-Q2) obtained by reacting dimethylaminopropylacrylamide with 1-chloro-2-hydroxypropyltrimethylammonium chloride. Abbreviated). This DMAPAA-Q2 is represented by the general formula (1) of the above cationic monomer: R ₁ = H, R ₂ = propylene group, A = NH, R ₃ and R ₄ are each methyl group, R ₅ = CH ₂ CH ( OH) CH ₂ N ⁺ (CH ₃ ) ₃ Cl ⁻ , X = compound corresponding to chlorine.
On the other hand, the diallyldialkylammonium halide belonging to the quaternary ammonium base-containing cationic monomer is, for example, diallyldimethylammonium chloride (abbreviated as DADMAC).

The anionic monomer (c), which is a structural unit of the water-soluble amphoteric PAM copolymer, is α, β-unsaturated carboxylic acid or α, β-unsaturated sulfonic acid as shown in the present invention 4 .
The unsaturated carboxylic acids are (meth) acrylic acid, (anhydrous) maleic acid, fumaric acid (abbreviated as FA), itaconic acid (abbreviated as IA), (anhydrous) citraconic acid, its sodium, potassium, ammonium salt, etc. .
Examples of the unsaturated sulfonic acids include vinyl sulfonic acid, (meth) allyl sulfonic acid, styrene sulfonic acid, sulfopropyl (meth) acrylate, 2- (meth) acrylamide-2-methylpropane sulfonic acid, and salts thereof.

Among the structural units of the water-soluble amphoteric PAM copolymer, the content of (meth) acrylamide (a) is such that the molecular skeleton of the copolymer to be aggregated with filler is optimized, the cationic monomer (b), It can be arbitrarily selected within the range that can ensure the optimization of the content of the anionic monomer (c).
The cationic monomer (b) can be used singly or in combination, and the content relative to the amphoteric copolymer can be arbitrarily selected within a range in which the polymers do not repel each other due to a saturated cationic charge.
The anionic monomer (c) can be used alone or in combination, and can be arbitrarily selected within the range where the water solubility does not decrease due to the fixation of the carboxyl group (acid) in the low pH region.

In the water-soluble amphoteric PAM copolymer of the present invention, the component (a) to (b), or in addition to this, the component (c) is a constituent component, and the crosslinkable monomer (d) and / or the chain is used. The transfer agent (e) is used to give the copolymer a branched cross-linked structure.
The cross-linking monomer (d) contributes to increase the molecular weight of the copolymer and increase the active site for yielding ash, and bis (methylenebisacrylamide (abbreviated as MBAM), ethylenebis (meth) acrylamide, etc. Di (meth) acrylates such as meth) acrylamides, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dimethylacrylamide (abbreviated as DMAM), methacrylonitrile, and the like can be used.
The chain transfer agent suppresses an increase in the viscosity of the copolymer, acts to adjust the molecular weight by increasing the branched structure, isopropyl alcohol (abbreviated as IPA), sodium methallylsulfonate (abbreviated as SMS), n- Known chain transfer agents such as mercaptans such as dodecyl mercaptan, mercaptoethanol and thioglycolic acid can be used.
Further, in the water-soluble amphoteric copolymer, if necessary, a nonionic monomer such as acrylonitrile may be used as another monomer.

When the water-soluble polymer substance (B) of the present invention is a water- soluble cationic PAM copolymer, component (a) and component (b) are constituent components of the amphoteric PAM copolymer. Obtained by a polymerization reaction.
In the case of this cationic copolymer, specific compounds that can be used in the components (a) to (b) are the same as in the case of the amphoteric copolymer. Moreover, the point which can use nonionic monomers, such as acrylonitrile, as another monomer as needed is the same as that of the amphoteric copolymer.
Further, as in the case of the amphoteric copolymer, a crosslinkable monomer (d) and / or a chain transfer agent (e) is used to give a branched crosslinked structure to the copolymer.

In the present invention, as the water-soluble polymer substance (B), the amphoteric and cationic polymer substances can be used singly or in combination. The amount added to the pulp slurry is arbitrary and is not particularly limited. In the water-soluble polymer substance (B), amphoteric and anionic polymer substances are more effective.
The water-soluble polymer substance (B) preferably has a molecular weight of about 500,000 to 10,000,000, more preferably 1,000,000 to 6,000,000. In general, when the molecular weight increases, the cation charge amount and / or the anion charge amount increase, which contributes to the improvement of the ash capturing function.
In order to adjust the molecular weight of the water-soluble polymer substance (B), the crosslinkable monomer or chain transfer agent is used. Further, for example, the use of the DMAPAA-Q2 bis-quaternary base-containing monomer as the component (b) contributes to an increase in the charge amount of the polymer.
On the other hand, the additive for deinked pulp of the present invention is a mixture of a hardly soluble substance (A) and a water-soluble polymer substance (B), but the combination of these two is arbitrary and is not particularly limited.

The present invention is characterized in that an additive for deinked pulp comprising the above components (A) and (B) is added to a pulp slurry.
Explaining this addition mode, the components (A) and (B) may be added simultaneously to the pulp slurry, or may be added with a time difference. In the case of simultaneous addition, for example, a dilute mixed solution of component (A) and component (B) may be prepared in advance, and this mixed solution may be added to the pulp slurry, or in the production process of component (B) Component (A) may be added to the resulting aqueous solution to prepare a composite solution of components (A) and (B) (ie, one solution), and this composite solution may be added. In addition by the time difference, the component (B) may be added after the component (A), or vice versa.
As described above, in the present invention, the silicate filler that has been atomized or dissolved under strong alkaline conditions is re-solubilized with the component (A), and the hardly-solubilized product is smoothly aggregated with the component (B). It is particularly suitable for producing deinked pulp derived from newspaper waste paper.
Needless to say, in the additive of the present invention, a known flocculant (such as a cationic polymer) can be used in addition to the components (A) and (B).

Hereinafter, among the water-soluble polymer substance (B) of the present invention, synthesis examples of ionic PAM copolymers, PAM copolymers obtained in each synthesis example, or water-soluble polymers other than PAM series Examples of manufacturing deinked pulp derived from newspaper wastepaper using additives for deinked pulp, which is a combination of a substance (ie, component (B)) and a hardly soluble substance (A), and deinking obtained in each example The measurement test example of the yield rate (%) of the ash content including the filler in the pulp sheet will be sequentially described. “%” And “part” described in each synthesis example and example are basically based on weight.
Note that the present invention is not limited to the following synthesis examples and examples, and it is needless to say that arbitrary modifications can be made within the scope of the technical idea of the present invention.

<< Synthesis Example of Water-Soluble Ionic PAM Copolymer >>
Among Synthesis Examples 1 to 4 and Reference Synthesis Example 1 below, Synthesis Examples 1 and 4 are examples in which the water-soluble ionic PAM copolymer (B) is a cationic copolymer, and Synthesis Example 1 is cationic. Example in which tertiary amino group-containing acrylamide is used for monomer (b), Synthesis Example 4 is a hardly soluble substance (A) after polymerization reaction using quaternary ammonium base-containing acrylamide in (b). This is an example in which calcium chloride is added. Reference synthesis example 1 is an example in which component (B) is an anionic copolymer. Synthesis Examples 2 to 3 are examples in which the component (B) is an amphoteric copolymer, Synthesis Example 2 is an example in which a quaternary ammonium base-containing methacrylate is used as the cationic monomer (b), and Synthesis Example 3 is the same as (b). In this example, diallyldialkylammonium chloride is used.
Incidentally, the property values such as the composition, viscosity, solid content and the like of each PAM copolymer aqueous solution obtained in Synthesis Examples 1 to 4 and Reference Synthesis Example 1 are summarized in FIG. Further, in FIG. 1, the contents of the following crosslinking agent (d) and chain transfer agent (e) are expressed in mol% with respect to the total molar amount of the monomer components (a) to (c).

(1) Synthesis example 1
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, 121 g (71 mol%) of 50% acrylamide aqueous solution, 7.5 g (4 mol%) of dimethylaminopropyl acrylamide, 3.6 g of isopropanol (5 mol%) and 236 g of ion-exchanged water were charged, the pH was adjusted to 3 with sulfuric acid, and oxygen in the reaction system was removed through nitrogen gas.
Next, the system was brought to 55 ° C., and 5 g of 1% ammonium persulfate aqueous solution was added as a catalyst under stirring, and then the temperature was raised to 90 ° C. Thereafter, 41.0 g (24 mol%) of 50% acrylamide aqueous solution and 1.87 g (1 mol%) of dimethylaminopropylacrylamide were mixed, and an aqueous monomer solution adjusted to pH 3 with sulfuric acid was added, followed by additional catalyst. 5 g of 1% ammonium persulfate aqueous solution was added, and the temperature was maintained for 3 hours while controlling the heat of polymerization.
When an appropriate viscosity is reached, 50 g of water is added and cooled to terminate the reaction, and the cationic PAM copolymer having a pH of 4.5, a solid content of 20.7%, and a viscosity (25 ° C.) of 4900 mPa · s is obtained. An aqueous solution was obtained.

(2) Synthesis Examples 2-3 and Reference Synthesis Example 1
Various ionic PAMs were prepared in the same manner as in Synthesis Example 1 except that the types and contents of components (a) to (e) were changed as shown in FIG. An aqueous copolymer solution was obtained.

(3) Synthesis example 4
Based on Synthesis Example 1, the types and contents of components (a) to (e) were changed to acrylamide 85 mol%, acrylamidopropyltrimethylammonium chloride 15 mol%, and methallyl sodium sulfonate 0.2 mol%. The cationic PAM copolymer aqueous solution was obtained in the same manner as in Synthesis Example 1, and 100 g (same weight as the polymer part) of calcium chloride was mixed in the aqueous solution.

Therefore, each of the water-soluble ionic PAM copolymers of Synthesis Examples 1 to 4 and Reference Synthesis Example 1 or a water-soluble copolymer other than PAM-based is used as a water-soluble polymer substance (B), and water-soluble silicic acid. A deinked pulp sheet is obtained from a pulp slurry containing a large amount of waste newspaper paper by using a mixture of a substance (A) that hardly dissolves salt and the water-soluble polymer substance (B) as an additive for deinked pulp. An example of manufacturing will be described.
<< Examples of production of deinked pulp sheet derived from waste newspaper using both component (A) and component (B) >>
As shown in the left two columns of FIG. 2, among Examples 1 to 4 and Reference Examples 1 to 4 below, Examples 1 to 4 are the hardly soluble substance (A), Synthesis Examples 1 to 3 and Reference Synthesis Example 1 (That is, PAM-based water-soluble copolymer (B)) is added after the flotation step, and Reference Examples 2 to 4 are poorly soluble substances (A) and water-soluble polymer substances other than PAM-based substances ( In this example, B) is added after the flotation step. Example 4 is an example in which an aqueous solution of the component (B) was prepared, and then the component (A) was added to make one solution, which was added after the flotation step. Examples 1 to 3 and Reference Examples 1 to 2 are examples in which the component (A) is added to the pulp slurry and then the component (B) is added. In Reference Example 3 , the component (B) is added after the component (B) is added. This is an example in which A) is added. Reference Example 4 is an example in which a diluted mixture of component (A) and component (B) was added (that is, added simultaneously). Example 4 is an example in which the composite aqueous solution of components (A) and (B) was added as described above.

On the other hand, among the following Comparative Examples 1 to 6, Comparative Examples 1 to 5 are examples in which various chemicals are added after the flotation step or not added, and Comparative Example 6 is based on Patent Document 2 described above. In this example, the additive for deinking pulp of the present invention comprising components (A) and (B) is added during the flotation step (see the left column 2 in FIG. 2).
Of the above Comparative Examples 1 to 5, Comparative Example 1 is a blank example in which component (A) and component (B) are not used. Comparative Example 2 is a blank example with only Component A (acidifying agent) and no Component B. Comparative Example 3 is a blank example with only component A (polyvalent metal salt) and no component B. Comparative Example 4 is a blank example having only Component B (the cationic PAM copolymer of Synthesis Example 1) and no Component A. Comparative Example 5 is a combination example of Component B (cationic PAM copolymer of Synthesis Example 5) and a drug (potassium hydroxide) other than Component A that has no silicate sparing function. Comparative Example 6 is an example in which the acidifying agent (component (A)) and the cationic PAM copolymer (component (B)) of Synthesis Example 1 were added.

(1) Example 1
First, a newspaper waste paper and a leaflet blended with newspaper waste paper / flyer = 70/30 (weight ratio) (15% ash content) are immersed in tap water all day and night, and disaggregated in a Niagara-type beater. Diluted to 2%. A commercial deinking agent Haritop P-320 (manufactured by Harima Chemicals Co., Ltd.) was added thereto, and deinking treatment was performed by a flotation method.
Next, 1% sulfuric acid is added to the slurry from which the ink components have been removed by flotation, followed by the water-soluble polymer aqueous solution of Synthesis Example 1 at a ratio of 0.1% to pulp with stirring. The wet sheet was obtained by pouring and dehydrating.
This sheet was dried in a dryer at 105 ° C. for 6 hours, and after measuring the weight of the dried pulp, the ash content on the pulp sheet was measured according to JIS P8003, and the initial ash content (15%) was measured. Yield rate (%) was calculated.

(2) Examples 2 to 3, Reference Examples 1 and 2
Based on the above Example 1, the additives added to the pulp slurry were changed as shown in FIG. 2, and the other operations were performed in the same manner as in Example 1 to measure the ash content of the dried sheet.

(3) Reference example 3
Based on Example 1 above, polyethyleneimine (component (B)) was added to the pulp at 0.1%, followed by polyaluminum chloride (component (A)) at a ratio of 1% to pulp. The ash content of the dried sheet was measured in the same manner as in Example 1 except that the order of adding the component (A) and the component (B) was reversed.

(4) Reference example 4
Based on Example 1 above, a solution prepared by diluting and mixing a polyferric sulfate aqueous solution (component (A)) and a polyamide polyamine-epichlorohydrin resin aqueous solution (component (B)) immediately before addition is added to the pulp slurry. The same operation as in Example 1 was performed to measure the ash content of the dried sheet.

(5) Example 4
Based on Example 1 above, the composite aqueous solution of calcium chloride / cationic PAM copolymer obtained in Synthesis Example 4 was added to the pulp slurry, and other operations were performed in the same manner as in Example 1 and dried. The ash content of the sheet was measured.

(6) Comparative example 1
Based on Example 1, the ash content of the dried sheet was measured by performing the same operation as Example 1 except that the additive for deinking pulp of the present invention was not added to the slurry after flotation. did.

(7) Comparative Examples 2-5
Based on the above Example 1, the additives added to the pulp slurry were changed as shown in FIG. 2, and the other operations were performed in the same manner as in Example 1 to measure the ash content of the dried sheet.

(8) Comparative Example 6
Commercially available deinking agent Halitop P-320 was added to the pulp slurry, and 1% sulfuric acid was added to the pulp in accordance with Example 1 during the ink separation process by the flotation method, followed by the water solubility of Synthesis Example 1. A cationic PAM copolymer aqueous solution was added.
However, in this case, a slurry containing a large amount of cohesive bubbles and ash aggregates associated with the resin component such as detached ink is produced, and the deinking process itself is hindered. did.

《Evaluation test result of yield rate of ash including filler》
The right column of FIG. 2 shows the yield rate of ash in the dry sheet obtained by the method for producing deinked pulp derived from each newspaper waste paper of Examples 1 to 4, Reference Examples 1 to 4 and Comparative Examples 1 to 6 ( %) (Excluding Comparative Example 6).
According to this, first, the yield of ash was 4.9% in Comparative Example 1 in which the additive for deinking pulp of the present invention was not added at all in the deinking step. On the other hand, Examples 1 to 4 and Reference Example 1 in which the additive for deinked pulp of the present invention using the predetermined poorly soluble substance (A) and the water-soluble polymer (B) in combination was added after the flotation step. In -4, the yield of ash is 8.6 to 10.4%, and when the additive for deinked pulp of the present invention is used, the yield of ash is remarkable as compared with Comparative Example 1 which is a blank example. It was confirmed that it was improved.
Next, in Comparative Examples 2 to 3 in which only the poorly soluble substance (A) is added and the water-soluble polymer substance (B) is not added, the yield of ash is only 5.4 to 5.7%. Although it was high, it was inferior to Examples 1-8. On the contrary, even in Comparative Example 4 in which only the cationic PAM copolymer (component (B)) is added and the hardly soluble substance (A) is not added, the yield of ash content is at a level similar to that in Comparative Examples 2 and 3 above. It was still inferior to Examples 1-4 and Reference Examples 1-4 . Further, in Comparative Example 5 in which the cationic PAM copolymer (component (B)) and a drug having no sparingly soluble function (potassium hydroxide) are used in combination, the yield of ash is somewhat improved compared to Comparative Examples 2 to 4 above. However, it did not reach Examples 1-4 and Reference Examples 1-4 .
Therefore, not only the poorly soluble substance (A) is added, but also when only the water-soluble polymer substance (B) is added, or when the drug having no poorly soluble function is used in combination with the component (B). In comparison, it was revealed that the yield of ash can be improved more effectively when the additive of the present invention in which the poorly soluble substance (A) and the water-soluble polymer substance (B) are combined is used. As a result, the silicate filler that has been atomized or dissolved by deinking treatment under strong alkaline conditions is re-solubilized with component (A), and the hardly-solubilized material is smoothly aggregated with component (B). This proved the superiority of the method of the present invention over the prior art in that the ash containing the filler is recovered with a good yield.
And this test example evaluated the yield of the ash content for the pulp slurry of newspaper waste paper / flyer = 70/30 (weight ratio), and this invention is contained in many deinked pulp derived from newspaper waste paper. It has been found to be particularly suitable for improving the yield of silicate fillers.
On the other hand, in Comparative Example 6 in which the components (A) and (B) of the present invention were added during the flotation process, as described above, strong sticky bubbles were generated and the deinking process itself was hindered. It has become clear that it is important to add the deinking pulp additive of the present invention not after the flotation step but after the flotation step.
As described above, since most of the ash with a high specific gravity is discharged out of the system together with water from the pulp slurry system by dehydration, the additive of the present invention can be used in the dehydration process even after the flotation process. Must be added before.

Therefore, the test evaluation of Examples 1 to 4 and Reference Examples 1 to 4 will be described in detail.
First, paying attention to the poorly soluble substance (A), it is effective for improving the yield of ash regardless of the acidifying agent and the polyvalent metal compound, but the use of the polyvalent metal compound is more effective for the acidifying agent. As a result, the yield of ash was improved (see, for example, Examples 2-3 and Reference Examples 2-4). In addition, as the polyvalent metal-based compound, those exhibiting acidity such as polyaluminum chloride were effective (see Reference Example 3 and the like).
Next, when paying attention to the water-soluble polymer substance (B), a PAM copolymer (see Examples 1 to 3 and Reference Example 1) and a polymer substance other than the PAM system (see Reference Examples 2 to 4) are used. The PAM copolymer was effective regardless of amphotericity or cationicity .
Further, looking at the addition modes of components (A) and (B), it was effective to add components (A) and (B) with a time lag or at the same time. Addition with a time difference was effective regardless of the order of addition of components (A) and (B) (see Examples 1 to 3 and Reference Examples 1 to 3). In addition, in the simultaneous addition, diluted solutions of components (A) and (B) after production may be mixed (see Reference Example 4), or a composite solution in which component (A) is mixed after production of component (B). It was confirmed that may be added (see Example 4).

It is a graph which shows various properties, such as the monomer composition of each water-soluble ionic PAM type copolymer of the synthesis examples 1-4, and the reference synthesis example 1 , the viscosity of the obtained copolymer, and solid content. It is a graph which shows the yield rate of the ash content of the sheet | seat obtained by the manufacturing method of the deinking pulp derived from each newspaper waste paper of Examples 1-4, Reference Examples 1-4, and Comparative Examples 1-6.

Claims (4)

In the deinking process, in the method for producing deinked pulp, an additive for producing deinked pulp is added to a pulp slurry containing a silicate filler derived from used newspaper.
The additive for producing deinked pulp is a combination of (A) a substance that makes water-soluble silicate hardly soluble and (B) a water-soluble polymer substance,
(A) At least one kind selected from inorganic acids, C _{1 to} C ₄ organic acids, polyvalent metal salts, polyvalent metal oxides, polyvalent metal hydroxides, and polyvalent metal salt condensates as the poorly soluble substance And
(B) The water-soluble polymer substance comprises (a) (meth) acrylamide and (b) a cationic monomer as constituents, or (a) (meth) acrylamide and (b) a cationic monomer, (c) A water-soluble ionic polyacrylamide copolymer polymerized using (a ) an anionic monomer as a constituent, and (d) a crosslinkable monomer and / or (e) a chain transfer agent,
Production of deinked pulp characterized in that by adding the additive before the dehydration step of the pulp slurry from which the ink has been separated in the flotation step, it is possible to improve the yield of ash containing fillers derived from newspaper wastepaper. Method.   (A) The hardly-solubilized substance is at least one of a polyvalent metal oxide, a polyvalent metal hydroxide, and a polyvalent metal salt condensate, and (B) the water-soluble polymer substance is an amphoteric polymer substance. The method for producing deinked pulp according to claim 1. The cationic monomer (b) is a primary to tertiary amino group-containing (meth) acrylamide, primary to tertiary amino group-containing (meth) acrylate, quaternary ammonium base-containing (meth) acrylamide, quaternary ammonium base-containing (meth). It is at least 1 type of an acrylate and a diallyl dialkyl ammonium halide, The manufacturing method of the deinking pulp of Claim 1 or 2 characterized by the above-mentioned. 4. The deionization according to any one of claims 1 to 3, wherein the anionic monomer (c) is at least one of α, β-unsaturated carboxylic acids and α, β-unsaturated sulfonic acids. Manufacturing method of black pulp.

Images