JP2005042270A - Fluorescence retarder and method for retarding fluorescence - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescence retarder and a method for retarding fluorescence that can retard the fluorescence originating from fluorescent dye added to the used paper in no use of a low-molecular-weight organic halogen compound that is environmentally hazardous without unreacted formaldehyde or causing no liberation or emission of formaldehyde, when used paper in which fluorescent dye remains is recycled. <P>SOLUTION: This fluorescence retarder includes N-vinylformamide polymer and/or its derivatives and this method for retarding fluorescence employs N-vinylformamide polymer and/or its derivative as an active ingredient. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fluorescence inhibitor and a fluorescence suppression method, and more particularly, to low-molecular-weight organic halogen compounds (hereinafter referred to as environmentally harmful compounds) which are environmentally harmful in recycling of used paper, particularly in recycling of used paper having fluorescence derived from fluorescent dyes. The present invention relates to a method for suppressing fluorescence derived from a fluorescent dye without using AOX). Note that the used paper described here includes high-quality used paper, magazine used paper, newspaper used paper, ears in press processing that occur in the actual paper making process, and waste paper at the time of reel change or paper break. All papers that need to be regenerated or are recyclable, both wet and dry.

  In the manufacturing process of paper products, dyes are used because of the necessity of adjusting the color tone. In particular, in order to emphasize the whiteness of paper, it is essential to use a fluorescent dye. On the other hand, there are applications for paper products in which fluorescent color development is undesirable. In particular, there may be a demand for non-fluorescent coloring such as sanitary paper or food. In these cases, there is no problem if a new papermaking raw material is used. However, in practice, it is difficult to manufacture a paper product without using waste paper from the viewpoint of raw wood circumstances, energy saving and environmental problems. Further, in the actual paper making process, there is a loss of paper at the time of changing the ears and reels in the press working or at the time of cutting the paper. These waste papers are returned to the pulper and reused. In this case, it is not practical to separate and reuse the one containing the fluorescent dye and the one not containing the fluorescent dye. Under these circumstances, there is a demand for a method for suppressing the fluorescence of waste paper containing a fluorescent dye.

  As a conventional technique for suppressing the fluorescence of used paper, a method of suppressing the fluorescence in the used paper with sodium hypochlorite is disclosed (for example, see Patent Document 1), but the fluorescence suppressing ability is not sufficient. Further, a technique for suppressing fluorescence by a conventional fluorescent whitening agent using dichlorisocyanuric acid soda has been disclosed (for example, see Patent Document 2), but dichlorisocyanuric acid soda itself has a low level. It is a molecular organic halogen compound, and a large amount of AOX is contained in the used paper whose treatment has been reduced in fluorescence, treated water, and washing water. This is extremely undesirable from the viewpoint of environmental problems that have been recently closed up. Although a technique for suppressing the AOX concentration in pulp treatment liquid and washing liquid by using dichlorisocyanuric acid soda under conditions where the waste paper pulp concentration is high is disclosed (for example, see Patent Document 3). Since chlorisocyanurate sodium is still used, it is difficult to make the AOX concentration zero. In addition, as a conventional technique that does not use a low-molecular organic halogen compound, a fluorescence suppression method using a melamine / formalin resin is known. However, since the effect is insufficient, there is unreacted formaldehyde or free formaldehyde. It is hard to say that it is preferable.

JP 62-97993 A

Japanese Patent Publication No. 48-1693 JP-A-6-33387

  The present invention does not use environmentally harmful low-molecular organic halogen compounds, recycles unreacted formaldehyde and formaldehyde, and recycles waste paper containing fluorescent dyes. An object of the present invention is to provide a fluorescence inhibitor and a fluorescence suppression method capable of suppressing the fluorescence of the light. As a result of various studies, the present inventors have found that N-vinylformamide-based polymers and derivatives thereof function as a fluorescence inhibitor and add them when recycling used paper containing a fluorescent dye. As a result, the present inventors have obtained the knowledge that can be effectively suppressed.

The present invention provides an agent and method for effectively suppressing the fluorescence of used paper by adding a fluorescence inhibitor when recycling used paper containing a fluorescent dye.
That is, the first means for solving the problems in the present invention is as follows:
(1) A fluorescence inhibitor containing an N-vinylformamide polymer and / or a derivative thereof.
That is, the second means for solving the problem in the present invention is as follows.
(2) The derivative of the N-vinylformamide polymer is hydrolyzed at a hydrolysis rate of 20 mol% to 100 mol% with respect to the total formyl groups of the formyl group in the N-vinylformamide polymer. The fluorescence suppressor according to (1) above, which is a hydrolyzate of an N-vinylformamide polymer.

That is, the third means for solving the problem in the present invention is as follows.
(3) A fluorescence suppression method characterized by using the fluorescence inhibitor described in (1) or (2) above when recycling waste paper containing a fluorescent dye.
That is, the 4th means for solving the above-mentioned subject in the present invention is as follows.
(4) The fluorescence suppression method according to (3), wherein the fluorescence suppression agent according to (1) or (2) is added at the time of waste paper pulp preparation. In addition, as "at the time of used paper pulp preparation", the arbitrary time which prepares used paper pulp can be mentioned, For example, the time in the process of disaggregating used paper pulp and the process of storing used paper pulp slurry can be made into a suitable example. .

  According to the method of suppressing the fluorescence of waste paper using the fluorescence inhibitor obtained by the present invention, it is possible to avoid using environmentally harmful AOX in the regeneration of waste paper having fluorescence derived from a fluorescent dye, There is no unreacted formaldehyde or free formaldehyde, and the fluorescence derived from the fluorescent dye can be effectively reduced.

  The fluorescence inhibitor according to the present invention includes an N-vinylformamide polymer and / or a derivative thereof.

  The N-vinylformamide polymer is obtained by copolymerizing a homopolymer obtained by polymerizing N-vinylformamide or N-vinylformamide and a monomer copolymerizable with this N-vinylformamide. Copolymers (hereinafter, the homopolymer and the copolymer are collectively referred to simply as “polymer”) may be mentioned. In the present invention, a mixture of the homopolymer and the copolymer can also be used.

  Examples of the monomer copolymerizable with the N-vinylformamide include a vinyl compound having a side chain group containing a nitrogen atom, a vinyl ester or propenyl ester of a saturated carboxylic acid, a nonionic (meth) allyl monomer, and a nitrogen atom. (Meth) allyl monomer having side chain group, olefin, ethylenically unsaturated carboxylic acid, ester or amide of the above ethylenically unsaturated carboxylic acid, monomer having nitrile group, monomer having sulfonic acid group, phosphoric acid Examples thereof include a monomer having a group and a styrene monomer.

  Examples of the vinyl compound having a side chain group containing a nitrogen atom include N-vinylcarboxylic acid amides such as N-vinylacetamide and N-vinylpropionic acid amide, N-methyl-N-vinylacetamide and N-ethyl- N-substituted N-vinylcarboxylic amides such as N-vinylacetamide, N-vinyl lactams such as N-vinylpyrrolidone and N-vinylcaprolactam, N-vinyl-N-methylamine and N-vinyl-N-ethylamine N-vinyl-N-alkylamine formed by bonding an alkyl group having 1 to 6 carbon atoms to a nitrogen atom, N-vinylimidazole, 2-vinylimidazole, N-vinyl-2-methyl-imidazole, N-vinyl-4-methyl-imidazole, N-vinyl-5-methylimidazole, N List vinyl heterocyclic compounds such as vinyl-2-ethylimidazole, N-vinylimidazoline, N-vinyl-2-methylimidazoline, N-vinyl-2-ethylimidazoline, N-vinyloxazole and N-vinyloxazoline. Can do.

  In addition, N-vinylimidazole and N-vinylimidazoline can also be used in the form neutralized with an acid and the quaternized form in addition to the free base form. Examples of the acid include mineral acids such as hydrochloric acid, carbonic acid, sulfuric acid, and nitric acid, and organic acids such as carboxylic acid and sulfonic acid such as formic acid, acetic acid, and propionic acid. The quaternization is performed with alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epihalohydrins such as epichlorohydrin and epibromohydrin. It can be carried out. Among these, a form containing no halogen is preferable.

  Examples of vinyl esters of saturated carboxylic acids include vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate.

  Examples of the propenyl ester of a saturated carboxylic acid include propenyl formate, propenyl acetate and propenyl propionate.

  Examples of the nonionic (meth) allyl monomer include (meth) allyl alcohol such as allyl alcohol and methallyl alcohol, (meth) allyl halide such as allyl chloride, allyl bromide, methallyl chloride and methallyl bromide, and allyl methyl. (Meth) allyl ether, allyl formate, allyl acetate, allyl propionate, meta having 1 to 18 carbon atoms, such as ether, allyl ethyl ether, methallyl methyl ether and methallyl ethyl ether, which are ether-bonded with an alkyl group. Mention may be made of (meth) allyl esters of saturated carboxylic acids having 1 to 18 carbon atoms, such as rilformate and methallyl acetate. Among these, a polymerization component having no halogen is preferable.

  Examples of the (meth) allyl monomer having a side chain group containing a nitrogen atom include (meth) allylamine such as allylamine and methallylamine, N-methylallylamine, N-ethylallylamine, N-stearylallylamine, and N-methylmethallylamine. N-alkyl (meth) allylamine, N, N-dimethylallylamine, N, N-diethylallylamine, N, N-, which binds a C1-C18 alkyl group to a nitrogen atom, such as N-ethylmethallylamine N, which binds an alkyl group having 1 to 18 carbon atoms to the nitrogen atom, such as dimethylmethallylamine, N, N-diethylmethallylamine, N-methyl-N-stearylmethallylamine and N, N-distearylmethallylamine N-dialkyl (meth) allylamine, N, N, N-trimethyl Allyl ammonium chloride, N, N, N-triethylammonium chloride, N, N, N-trimethylmethallyl ammonium chloride, N, N, N-triethylmethallyl ammonium chloride, N-methyl-N, N-distearylmethallyl N, N, N-trialkyl (meth) allyl ammonium halides and diallylamines, such as ammonium chloride and N, N-dimethyl-N-stearylmethallyl ammonium chloride, which bind an alkyl group having 1 to 18 carbon atoms to a nitrogen atom And di (meth) allylamine such as dimethallylamine, N-methyldiallylamine, N-ethyldiallylamine, N-methyldimethallylamine, N-ethyldimethallylamine, and N-stearyldimethallylamine. Archi N-alkyldi (meth) allylamine, which bonds the group to the nitrogen atom, as well as N, N-dimethyldiallylammonium chloride, N, N-diethyldiallylammonium chloride, N, N-dimethyldimethallylammonium chloride, N, N-diethyl Examples thereof include N, N-dialkyldi (meth) allyl ammonium halides that bond an alkyl group having 1 to 18 carbon atoms to a nitrogen atom, such as dimethallyl ammonium chloride and N, N-distearyl dimethallyl ammonium chloride. . Among these, (meth) allyl monomers containing no halogen are preferable.

  The (meth) allylamine, N-alkyl (meth) allylamine, N, N-dialkyl (meth) allylamine, N-alkyldi (meth) allylamine and the like are in a form neutralized with an acid in addition to the free base form, and Quaternized forms can also be used. Examples of the acid include mineral acids such as hydrochloric acid, carbonic acid, sulfuric acid and nitric acid, and carboxylic acids such as formic acid, acetic acid and propionic acid, and organic acids such as sulfonic acid. The quaternization includes, for example, alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin and epibromohydrin. The epihalohydrin can be used. Among these, a form containing no halogen is preferable.

  Examples of olefins include ethylene, propylene, and butadiene.

  Examples of the ethylenically unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, cinnamic acid, and vinyl ester acid. , 2- (meth) acrylamide glycolic acid, α, β-unsaturated tricarboxylic acid, and α, β-unsaturated tetracarboxylic acid, and alkali metal salts, alkaline earth metal salts and ammonium salts thereof. it can.

  Examples of the ethylenically unsaturated carboxylic acid ester include 1 to 18 such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl acrylate and stearyl acrylate. (Meth) acrylic acid ester, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, 2-methoxybutyl acrylate, 2-methoxy ester-bonded to an alkyl group having a carbon atom Acrylic acid monoe of butyl methacrylate and polyalkylene glycol having a molecular weight of 500 to 10,000 (Meth) acrylic acid ester in which only one hydroxyl group is esterified, such as ter, and dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, dimethylaminopropyl acrylate, dimethylaminopropyl Mention may be made of esters of aminoalcohol and (meth) acrylic acid, such as methacrylate, diethylaminopropyl acrylate, dimethylaminobutyl acrylate and diethylaminobutyl acrylate.

  In addition, the carboxylic acid ester of amino alcohol can be used in a form neutralized with an acid and a quaternized form in addition to the form of the free base. Examples of the acid include mineral acids such as hydrochloric acid, carbonic acid, sulfuric acid and nitric acid, and carboxylic acids such as formic acid, acetic acid and propionic acid, and organic acids such as sulfonic acid. The quaternization includes, for example, alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin and epibromohydrin. The epihalohydrin can be used. Among these, a form containing no halogen is preferable.

  Examples of the amide of the unsaturated carboxylic acid include acrylamide, methacrylamide, N-methylacrylamide, N, N-dimethylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N-isopropylacrylamide and Nt-butyl. N-alkyl monoamides and diamides of monoethylenically unsaturated carboxylic acids having an alkyl group of 1 to 6 carbon atoms, such as acrylamide, and dimethylaminoethylacrylamide, dimethylaminoethylmethacrylamide, diethylaminoethylacrylamide, diethylaminoethylmethacrylate Amides, dimethylaminopropyl acrylamide, diethylaminopropyl acrylamide, dimethylaminopropyl methacrylamide and diethylaminopropyl methacrylate Carboxyls such as N, N-dialkylaminoalkyl (meth) acrylamides derived from N, N-dialkylaminoalkyl (meth) acrylamides such as luamide, in which each amino group is only amidated each time. An acid amide etc. can be mentioned.

  The N, N-dialkylaminoalkyl (meth) acrylamide may be used in a form neutralized with an acid and a quaternized form in addition to the free base form. Examples of the acid include mineral acids such as hydrochloric acid, carbonic acid, sulfuric acid and nitric acid, and carboxylic acids such as formic acid, acetic acid and propionic acid, and organic acids such as sulfonic acid. The quaternization includes, for example, alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin and epibromohydrin. The epihalohydrin can be used. Among these, a form containing no halogen is preferable.

  Examples of the monomer having a nitrile group include acrylonitrile, methacrylonitrile, and 2-methyleneglutaronitrile.

  Examples of the monomer having a sulfonic acid group include vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, isoprene sulfonic acid, 3-allyloxy-2-hydroxy-propane sulfonic acid, styrene sulfonic acid, and acrylic acid-3- Sulfopropyl ester, 2-acrylamido-2-methylpropanesulfonic acid, 2-methacrylamide-2-methylpropanesulfonic acid, sulfoethyl acrylate, hydroxyethyl acrylate sulfate, polyoxyalkylene oxide sulfate and Examples thereof include alkali metal salts, alkaline earth metal salts, and ammonium salts of these acids.

  Examples of the monomer having a phosphoric acid group include vinylphosphonic acid, styrenephosphonic acid, and alkali metal salts, alkaline earth metal salts, and ammonium salts thereof.

  Examples of the styrenic monomer include styrene, α-methylstyrene, α-methylstyrene dimer, and vinylbenzylamine. Vinylbenzylamine can be used in a form neutralized with an acid and a quaternized form in addition to the free base form. Examples of the acid include mineral acids such as hydrochloric acid, carbonic acid, sulfuric acid and nitric acid, and carboxylic acids such as formic acid, acetic acid and propionic acid, and organic acids such as sulfonic acid. The quaternization includes, for example, alkyl halides such as methyl chloride and methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, and epichlorohydrin and epibromohydrin. The epihalohydrin can be used. Among these, a form containing no halogen is preferable.

  The N-vinylformamide-based polymer can be made into a graft copolymer or a block copolymer by graft polymerization or block copolymerization of N-vinylformamide and the monomer.

  The N-vinylformamide polymer is composed of 100 to 1 mol% of N-vinylformamide and 0 to 99 mol% of monomer copolymerizable therewith, preferably 100 to 50 mol% of N-vinylformamide and monomer copolymerizable therewith. It can be obtained by polymerization at 0 to 50 mol%.

  In producing the N-vinylformamide polymer, any one of an ionic polymerization method such as anionic polymerization and cationic polymerization, and a radical polymerization method may be used. A radical polymerization method is preferred from the viewpoint that the molecular weight can be easily controlled. For example, a method described in JP-A-11-322849 can be employed.

  The polymerization method for the N-vinylformamide polymer can be performed by methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. The polymerization reaction is generally performed under an inert gas stream and usually at a temperature of 30 to 100 ° C.

  As the solution polymerization, water or a polar solvent in which N-vinylformamide can be dissolved is used as a solvent, and the polymerization is usually performed in an aqueous solution having a monomer concentration of 5 to 60% by mass. An aqueous solution having a concentration of 20 to 80% by mass is polymerized in a dispersed state of water in oil using a hydrophobic solvent and a dispersion stabilizer. In the emulsion polymerization, an aqueous solution having a monomer concentration of 20 to 60% by mass is usually polymerized in an oil-in-water type or a water-in-oil type emulsion state using a hydrophobic solvent and an emulsifier.

  In producing the polymer, a conventional polymerization initiator can be used as a radical polymerization catalyst used in a polymerization reaction, particularly a radical polymerization reaction. As the polymerization initiator, azo polymerization initiators, persulfates, peroxides, bromates, perborates, percarbonates, perphosphates, and the like can be used. Specifically, as an azo polymerization initiator, azobisisobutyronitrile, 2,2′-azobis- (2,4′-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2, 4-dimethylvaleronitrile), 2,2′-azobis (2-methylpropionitrile), 2,2′-azobis (2-methylbutyronitrile), 1,1-azobis- (cyclohexane-1-carbonitrile) ), 2,2′-azobis- [2-methyl-N- (2-hydroxyethyl) propionamide], dimethyl 2,2′-azobis (2-methylpropionate), 2,2′-azobis- ( 2-amidinopropane), 2,2'-azobis- (2-amidinopropane), 2,2'-azobis- (N, N'-dimethyleneisobutylamine), 2,2'-azobis- (N, N ' Dimethyleneisobutylamine), 2,2′-azobis (2- (2-imidazolin-2-yl) propane), 2,2′-azobis (2- (2-imidazolin-2-yl) propane), and 4 , 4'-azobis- (4-cyanovaleric acid) and salts thereof. Examples of the persulfate include sodium persulfate, potassium persulfate, and ammonium persulfate. Examples of the peroxide include benzoyl peroxide, hydrogen peroxide, tert-butyl hydroperoxide, and di-tert-butyl peroxide. Examples of bromates include sodium bromate and potassium bromate. Examples of perborates include sodium perborate and ammonium perborate. Examples of the percarbonate include sodium percarbonate, potassium percarbonate, and ammonium percarbonate. Examples of the superphosphate include sodium perphosphate, potassium perphosphate, and ammonium perphosphate.

  These polymerization initiators can be used singly or in combination of two or more. Particularly preferred initiators include 2,2′-azobis-4-amidinopropane hydrochloride and acetate, 4,4′-azobis-4-cyanovaleric acid sodium salt, azobis-N, N′-dimethyleneisobutyl. Examples include amidine hydrochloride and sulfate.

  Peroxide polymerization initiators include sulfites such as sodium sulfite, bisulfites such as sodium bisulfite, metabisulfites such as sodium metabisulfite, N, N, N ′, N′-tetramethyl. It can also be used as a redox polymerization initiator in combination with a reducing agent such as an organic amine such as ethylenediamine or a reducing sugar such as aldose. These reducing agents may be used alone or in combination of two or more. You may use together.

  Polymerization is initiated by adding a polymerization initiator to the monomer solution. However, for the purpose of reducing unreacted monomers, a part of the polymerization initiator may be additionally added during the polymerization, or the polymerization initiator may be continuously added by a technique represented by a dropping method. May be. Further, a method of irradiating with radiation, electron beam, or ultraviolet light can be used. These methods can be used alone or in combination of two or more.

  In the polymerization, a chain transfer agent can be appropriately used as necessary. Chain transfer agents include compounds having one or more hydroxyl groups in the molecule, compounds having one or more mercapto groups in the molecule, and one or more carbon-carbon unsaturated bonds in the molecule. And compounds such as dibutyl peroxide, hypophosphorous acid, and the like. A chain transfer agent may be used individually by 1 type, and may use 2 or more types together.

  In the polymerization in the present invention, a crosslinking agent can be appropriately added as necessary. As the crosslinking agent used in the present invention, bifunctional polymerizable vinyl monomers such as di (meth) acrylates, bis (meth) acrylamides, and divinyl esters having two unsaturated bonds, vinyl group and chain transfer A monomer having a crosslinking action by having a functional group capable of generating a monomer, a monomer having a crosslinking action by having a vinyl group and a reactive group, a trifunctional polymerizable vinyl monomer having three unsaturated bonds, Examples include tetrafunctional polymerizable vinyl monomers having an unsaturated bond, water-soluble aziridinyl compounds, water-soluble polyfunctional epoxy compounds, and silicon-based compounds. These may be used alone or in combination of two or more. May be.

  In addition, polymerization of N-vinylformamide or copolymerization of N-vinylformamide and a monomer copolymerizable therewith does not impair the purpose of the present invention, and oxidized starch, cationized starch, amphoteric starch, and enzyme. It can also be performed in the presence of starches such as modified starches, celluloses such as carboxymethylcellulose, polyvinyl alcohols, and water-soluble polymers such as chitosan and gums.

  Examples of the derivative of the N-vinylformamide polymer used as a fluorescence inhibitor include a polymer (1) obtained by modifying a formyl group contained in a homopolymer of N-vinylformamide, N-vinylformamide Examples thereof include a polymer (2) obtained by modifying a formyl group contained in the copolymer, and a mixture (3) of the polymer (1) and the polymer (2).

  This modification includes (1) hydrolysis, (2) transamidation, (3) hydrolyzed amino group and alkyl halide such as methyl chloride, methyl bromide, aralkyl halides such as benzyl chloride and benzyl bromide, halogenated formate esters. Halogenated carboxylic acid esters such as halogenated acetates, dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, epihalohydrins such as epichlorohydrin and epibromohydrin, saturated aliphatic or aromatic glycidyl ether compounds, and urea (4) Amidine modification by hydrolysis in the presence of ammonia, and (5) cyclic hydrolysis obtained by heating a partially hydrolyzed derivative of a polymer having N-vinylformamide as a polymerization component. Amidine modification and the like, N- Nylformamide homopolymer and / or derivative obtained by hydrolysis of formyl group of copolymer with polymerizable vinyl monomer copolymerizable with N-vinylformamide, ie, N-vinylformamide polymer Hydrolysates are preferred. Among these, it is preferable to modify with a substance not containing halogen.

  The hydrolyzate of the N-vinylformamide polymer is a derivative obtained by hydrolyzing the formyl group in these polymers. This derivative is obtained by a known method such as acidic hydrolysis, basic hydrolysis, a method of acidic hydrolysis in a hydrophilic solvent such as alcohol containing water, and a method of alcoholysis under acidic conditions. It can be obtained by hydrolyzing the solution or dehydrating or drying to form a powder. Among these hydrolysis methods, an acidic or basic hydrolysis method is preferable. The hydrolysis rate is preferably 20% mol or more and 100% mol or less in order to efficiently exhibit the fluorescence suppression effect.

  Examples of the modifier used for acidic hydrolysis include any compound that acts as a strong acid such as hydrochloric acid, bromic acid, hydrofluoric acid, sulfuric acid, nitric acid, phosphoric acid, sulfamic acid, and methanesulfonic acid. However, since the hydrolyzate is easily dissolved in water, a monovalent acid is preferable.

  As the modifier used for basic hydrolysis, any compound that acts as a strong base such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and quaternary ammonium hydroxide can be used. Is done.

  Examples of the alcohol used in the case of alcoholysis include alcohols having 1 to 4 carbon atoms such as methanol, ethanol, isopropyl alcohol, and butanol, and methanol is preferable.

  The amount of the modifying agent used for the hydrolysis is appropriately used depending on the desired modification rate in the range of usually 0.05 to 5 times moles with respect to the formyl group in the N-vinylformamide polymer. . When performing hydrolysis, reaction temperature is 30-110 degreeC normally, and reaction time is 0.1 to 24 hours normally.

  The hydrolysis rate of the formyl group in the N-vinylformamide polymer containing at least N-vinylformamide as a monomer component is preferably 20% to 100%, more preferably 30 to 100%, based on all formyl groups in the polymer. preferable. If the hydrolysis rate is too low, the fluorescence suppression effect may be insufficient.

  During the hydrolysis, for the purpose of preventing gelation caused by impurities, modification may be carried out by optionally adding an antigelling agent such as hydroxylamine hydrochloride and hydroxylamine sulfate. In addition, hydrolysis can be performed after treatment with an antigelling agent before modification. Hydrolysis can be carried out with water or a homogeneous solution using a mixed solvent of water and a polar solvent such as methanol, or a heterogeneous solution comprising a polar solvent containing at least water and a nonpolar solvent such as hexane or toluene.

  By the polymerization operation, a polymerization product liquid containing an N-vinylformamide polymer is obtained.

  The solid content concentration of the N-vinylformamide polymer and / or derivative thereof in the polymerization product liquid obtained by the polymerization operation and / or derivative preparation operation thereof is usually 3 to 40% by mass. Further, the viscosity of the polymerization product solution is usually 100,000 mPa · s or less, preferably 20,000 mPa · s or less, as measured with a Brookfield rotational viscometer at 25 ° C. In the present invention, the polymerization product liquid can be used as it is and used as a fluorescence inhibitor according to the present invention. In addition, a polymer-containing solution obtained by dissolving the N-vinylformamide polymer and / or derivative thereof separated from the polymerization product solution in an appropriate aqueous solvent such as lower alcohol such as methanol, water, or a mixed solvent thereof. It can also be used as a fluorescence inhibitor.

  The amount of the fluorescence inhibitor according to the present invention varies depending on the concentration of the N-vinylformamide polymer and / or its derivative in the polymerization product solution and / or the polymer-containing solution. In general, when the polymerization product solution and / or the polymer-containing solution is used as a fluorescence inhibitor, the solid content concentration of the N-vinylformamide polymer and / or derivative thereof in the fluorescence inhibitor is 3 to 40% by mass. When the amount is within the range, the amount of the fluorescence inhibitor according to the present invention is preferably 0.01% by mass or more and less than 2% by mass based on the dry weight of the pulp slurry made from waste paper containing a fluorescent dye. . When the addition amount is less than 0.01% by mass, a sufficient fluorescence suppression effect may not be obtained. When the addition amount is 2% by mass or more, the pulp slurry obtained using the present invention is used. When a paper product is made, problems such as deterioration of the texture of the paper product and coloring of the paper product may occur.

  Since the fluorescence inhibitor according to the present invention does not contain a low molecular organic halogen compound and formaldehyde, and does not generate a low molecular organic halogen compound or free formaldehyde even when contacted with waste paper pulp, It is considered that low-molecular organic halogen compounds and formaldehyde contained in papermaking treated water are not increased.

  In order to efficiently express the fluorescence suppression effect of the fluorescence suppressor according to the present invention, before other additives are added, specifically, a pulper that disaggregates waste paper, a waste paper chest after disaggregation, etc. It is preferable to add the fluorescence inhibitor according to the present invention directly to the pulp slurry containing the fluorescent dye.

  When adding the fluorescence inhibitor according to the present invention, there is no particular limitation on the pH and temperature of the pulp slurry containing the fluorescent dye, and the conventional paper making conditions (pH 4-9, 10 ° C.-50 ° C.) It may be used as it is based on the addition conditions.

  As pulp contained in the pulp slurry, bleached or unbleached high-yield pulp such as kraft pulp, bleached or unbleached chemical pulp, groundwood pulp, mechanical pulp, thermomechanical pulp, chemithermomechanical pulp, etc. Furthermore, there can be used waste paper pulp such as waste newspaper, magazine waste, and corrugated waste paper. Among these, waste paper pulp is preferable, and the content of waste paper pulp contained in the pulp is usually 50% or more, preferably 70% or more. In addition to the above wood-derived pulp (referred to as wood pulp), pulp made from non-wood such as straw and kenaf may be used. Moreover, the mixture of the said pulp and synthetic fibers, such as polyamide, a polyimide, polyester, polyolefin, and polyvinyl alcohol, may be sufficient.

  Examples of the fluorescent dye include bis (triazinylamino) stilbenzyl sulfonic acid derivatives, coumarin derivatives, pyrazonin derivatives, naphthalimide derivatives, bisbenzoxazolyl derivatives, bisstyryl biphenyl derivatives, and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, it is not limited by an Example. % Is based on weight unless otherwise indicated.

Example 1
80 g (1125 mmol) of N-vinylformamide is dissolved in 385 g of water in a 2 L flask equipped with a stirrer, thermometer and nitrogen inlet tube. This is mixed with 0.65 g (2.4 mmol) of 2,2′-azobis- (2-amidinopropane) hydrochloride, oxygen is eliminated by introducing nitrogen, and the reaction solution is warmed to 55 ° C. After maintaining this temperature for 5 hours, it was further heated at 60 ° C. for 30 minutes. The viscous polymerization product thus obtained was mixed with 68.5 g (676 mmol) of 36% hydrochloric acid aqueous solution and kept at 90 ° C. for 2 hours for hydrolysis. The polymer separated from the solution after hydrolysis was subjected to ¹ H-NMR measurement, and the hydrolysis rate calculated from the proton intensity ratio derived from methylene of the formyl group and the polymer main chain was 60%. The obtained hydrolyzate-containing polymerization product liquid was used as fluorescence inhibitor A as it was. The Brookfield viscosity of the hydrolyzate-containing polymerization product liquid was 1400 mPs · s (25 ° C.).

Example 2
After obtaining a polymerization product solution in the same manner as in Example 1, the same procedure as in Example 1 was conducted except that the amount of 36% aqueous hydrochloric acid was reduced to 34.25 g (338 mmol). A hydrolyzate-containing polymerization product liquid in which 30% of the product was hydrolyzed was obtained. The Brookfield viscosity of the hydrolyzate-containing polymerization product liquid was 2400 mPa · s (25 ° C.). The obtained hydrolyzate-containing polymerization product liquid was used as fluorescence inhibitor B as it was.

Example 3
In a 2 L flask equipped with a stirrer, a thermometer and a nitrogen inlet tube, N-vinylformamide 56 g (787.5 mmol) and acrylonitrile 24 g (452.5 mmol) were dissolved in 920 g of water. 2,5'-Azobis- (2-amidinopropane) hydrochloride 0.65 g (2.4 mnol) was mixed with this, oxygen was removed by introducing nitrogen gas, and then the liquid in the flask was heated to 55 ° C. did. This temperature was maintained for 5 hours. Thereafter, the mixture was further heated at 60 ° C. for 30 minutes. Next, 48 g (236.6 mmol) of 36% aqueous hydrochloric acid was added to the flask, mixed, and then hydrolyzed by maintaining at 90 ° C. for 2 hours in the same manner as in Example 1. The hydrolyzate separated from the obtained hydrolyzate-containing polymerization product liquid was subjected to ¹ H-NMR measurement, and the hydrolysis rate calculated from the proton intensity ratio derived from the methylene group of the formyl group and the polymer main chain was 60%. there were. The hydrolyzate-containing polymerization product liquid thus obtained was used as fluorescence inhibitor C as it was.

Example 4
After obtaining the polymerization product solution by the same method as in Example 1, it was carried out under the same conditions as in Example 1 except that the amount of 36% hydrochloric acid aqueous solution was increased to 114.5 g (1129.4 mmol). A hydrolyzate-containing polymerization product liquid containing a hydrolyzate obtained by hydrolyzing 95% of the formyl group was obtained. The Brookfield viscosity of this hydrolysis-containing polymerization product liquid was 1100 mPa · s (25 ° C.). This hydrolyzate-containing polymerization product liquid was used as the fluorescence inhibitor D as it was.

Preparation of fluorescent dye-containing pulp slurry 1
Raw material (1% slurry, Canadian Standard Freeness 400) mixed with 90 parts by weight of LBKP and 10 parts by weight of NBKP, 1 part by weight of light calcium carbonate (TP121, manufactured by Okutama Kogyo Co., Ltd.), 0.2 stilbene-based anionic fluorescent dye 0.2 Part by weight, 0.5 part by weight of sulfuric acid band, 1 part by weight of cationized starch (CATO304, manufactured by NSC Japan), 0.05 part by weight of AKD sizing agent (AS267, manufactured by Seiko PMC Co., Ltd.) The papermaking pH was 7.9 and a handmade sheet having a basis weight of 160 g / m ² was prepared using a square sheet machine manufactured by Kumagai Riki Co., Ltd. The pH at the time of papermaking was 7.9. The handcrafted sheet was pressed under conditions of 410 kPa for 5 minutes and dried at 100 ° C. for 2 minutes. The obtained fluorescent dye-containing waste paper was cut into 2 cm square, water was added so that the pulp concentration would be 2%, and rough disaggregation was carried out using a disaggregator manufactured by Kumagaya Riki Kogyo Co., Ltd.

Example 5
While stirring, 1000 parts by weight of the fluorescent dye-containing pulp slurry was added with 0.1 part by weight of the fluorescence inhibitor A to the pulp solid content. After 1 minute, stirring was stopped and a hand-made sheet of 64 g / m ² was prepared with a paper machine. The pH at the time of papermaking was 7.9. The obtained handsheet was conditioned for 24 hours under conditions of 23 ° C. and 50% relative humidity, and then the fluorescence intensity was evaluated. The results are shown in Table 1.

  The obtained handsheet was conditioned at 23 ° C. and 50% relative humidity for 24 hours, and then whitened using a whiteness meter (Technidyne, Color Touch) and a light source containing an ultraviolet light component. Was measured (ISO whiteness measurement). Subsequently, the whiteness was measured again with a light source from which the ultraviolet light component was removed by a filter, and evaluation was performed as follows.

  Paper containing a fluorescent dye is whitened by ultraviolet light, but is not whitened by a light source that does not contain ultraviolet light. That is, the paper containing the fluorescent dye has a difference in whiteness value between the condition including ultraviolet light and the condition not including ultraviolet light (when measuring the whiteness with a light source including ultraviolet light, the light source not including ultraviolet light The whiteness value is higher than that measured by the above method), and the paper containing no fluorescent dye shows no difference in the whiteness value between the condition containing ultraviolet light and the condition not containing it.

  Therefore, whiteness was measured with a light source containing ultraviolet light and a light source not containing ultraviolet light, and the difference was confirmed to provide a means for confirming the effect of the fluorescence inhibitor. That is, the whiteness is measured with a light source including ultraviolet light and a light source not including ultraviolet light, and (whiteness with a light source including ultraviolet light) − (whiteness with a light source not including ultraviolet light) is defined as fluorescence intensity. did. When the difference became small, it was judged that the fluorescence was decreased by the fluorescence inhibitor.

  If the fluorescence intensity is 1 or less, the effect is clearly seen, but if it is 4 or more, it is difficult to say that the effect is effective.

Example 6
A sheet obtained by preparing in the same manner as in Example 5 except that 0.05 part by weight of the fluorescence inhibitor A was added to the pulp solid content was prepared, the fluorescence intensity was evaluated, and the results are shown in Table 1. Indicated.

Examples 7-9
A sheet obtained by preparing in the same manner as in Example 5 except that the fluorescence inhibitor A was changed to fluorescence inhibitor B, fluorescence inhibitor C, and fluorescence inhibitor D, respectively, and the fluorescence intensity was evaluated. The results are shown in Table 1.

Comparative Example 1
A sheet obtained by preparing in the same manner as in Example 5 except that the fluorescence inhibitor A was not used was prepared, the fluorescence intensity was evaluated, and the results are shown in Table 2.

Comparative Example 2
A sheet obtained by preparing in the same manner as in Example 5 except that the fluorescence inhibitor A was changed to a commercially available melamine / formalin resin was prepared, the fluorescence intensity was evaluated, and the results are shown in Table 2. .

Claims (4)

A fluorescence inhibitor comprising an N-vinylformamide polymer and / or a derivative thereof. An N-vinylformamide polymer derivative is obtained by hydrolyzing a formyl group in an N-vinylformamide polymer at a hydrolysis rate of 20 mol% to 100 mol% with respect to all formyl groups. The fluorescence inhibitor according to claim 1, which is a hydrolyzate of a vinylformamide polymer. A method for suppressing fluorescence, comprising using the fluorescence inhibitor according to claim 1 or 2 when recycling waste paper containing a fluorescent dye. The fluorescence suppression method according to claim 3, wherein the fluorescence suppression agent according to claim 1 or 2 is added during the preparation of used paper pulp.