JP2011001637A - Method for producing bleached pulp - Google Patents
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本発明は、リグノセルロース物質から漂白パルプを製造する方法に関する。さらに詳しく述べれば、オゾン使用量の少ないＥＣＦ（エレメンタリークロリンフリー）漂白パルプの褪色性を改善する方法に関する。 The present invention relates to a process for producing bleached pulp from lignocellulosic material. More specifically, the present invention relates to a method for improving the discoloration of ECF (elementary chlorin free) bleached pulp with a small amount of ozone.
製紙用化学パルプの漂白は、多段にわたる漂白処理により実施されている。従来より、この多段漂白には漂白剤として塩素系漂白薬品が使用されている。具体的には、塩素（Ｃ）、次亜塩素酸塩（Ｈ）、二酸化塩素（Ｄ）の組み合わせにより、たとえば、Ｃ−Ｅ−Ｈ−Ｄ、Ｃ／Ｄ−Ｅ−Ｈ−Ｅ−Ｄなどのシーケンスによる漂白が行われてきた。
ここで、「Ｃ」は、塩素処理段、「Ｈ」は、次亜塩素酸塩処理段、「Ｄ」は、二酸化塩素処理段、「Ｅ」は、アルカリ処理段を意味する。また、「−」は、「−」の直前に記載の処理段の工程の後、洗浄を行い、その後、「−」の直後に記載の処理段の工程を行なうことを意味する。さらに、「／」は、「／」の直前及び直後に記載の薬品等を併用した処理段を意味し、例えば、「Ｃ／Ｄ」は、塩素と二酸化塩素とを併用した処理段を意味する。
The bleaching of chemical pulp for papermaking is carried out by multi-stage bleaching. Conventionally, chlorine bleaching chemicals have been used as bleaching agents in this multistage bleaching. Specifically, by the combination of chlorine (C), hypochlorite (H), chlorine dioxide (D), for example, C-E-H-D, C / D-E-H-E-D, etc. Bleaching by the sequence has been carried out.
Here, “C” means a chlorine treatment stage, “H” means a hypochlorite treatment stage, “D” means a chlorine dioxide treatment stage, and “E” means an alkali treatment stage. Further, “-” means that after the process step described immediately before “-”, cleaning is performed, and then the process step described immediately after “-” is performed. Furthermore, “/” means a treatment stage using the chemicals etc. described immediately before and immediately after “/”. For example, “C / D” means a treatment stage using chlorine and chlorine dioxide together. .
しかし、これらの塩素系漂白薬品は漂白時に環境に有害な有機塩素化合物を副生し、この有機塩素化合物を含む漂白廃水の環境汚染が問題になっている。有機塩素化合物は一般にＡＯＸ法、たとえば米国環境庁（ＥＰＡ；ＭＥＴＨＯＤ−９０２０号）によって分析、評価される。 However, these chlorine bleaching chemicals produce organic chlorine compounds that are harmful to the environment during bleaching, and environmental pollution of bleaching wastewater containing these organic chlorine compounds has become a problem. Organochlorine compounds are generally analyzed and evaluated by AOX methods such as the US Environmental Agency (EPA; METHOD-9020).
有機塩素化合物の副生を低減・防止するには、塩素系薬品の使用量を低減するか、ないしは使用しない事が最も効果的であり、特に初段に分子状塩素を使用しないことが最も有効な方法である。この方法で製造されたパルプはＥＣＦ（エレメンタリークロリンフリー）パルプと呼ばれ、更に塩素系薬品を全く用いずに製造されたパルプはＴＣＦ（トータリークロリンフリー）パルプと呼ばれている。 It is most effective to reduce or prevent the use of chlorinated chemicals in order to reduce or prevent organochlorine by-products. Especially, it is most effective not to use molecular chlorine in the first stage. Is the method. Pulp produced by this method is called ECF (elementary chlorin-free) pulp, and pulp produced without using any chlorinated chemicals is called TCF (totally chlorin-free) pulp.
蒸解−酸素脱リグニン処理したパルプを初段に分子状塩素を用いない漂白方法として、初段に二酸化塩素を用いたＤ−Ｅｏ−Ｄ、Ｄ−Ｅｏｐ−Ｄ或いは、Ｄ−Ｅｏ−Ｄ−Ｄ、Ｄ−Ｅｏｐ−Ｄ−Ｄシークエンス、Ｄ−Ｅｏ−Ｐ−Ｄ、Ｄ−Ｅｏｐ−Ｐ−Ｄシークエンス（ｐまたはＰは過酸化水素）、また初段にオゾンを用いたＺ−Ｅｏｐ−Ｄ、Ｚ−Ｅｏ−Ｐ−Ｄ、ＺＤ−Ｅｏｐ−Ｄシークエンスによる漂白が一般に知られている。
ここで、「Ｚ」は、オゾン処理段を意味し、「Ｐ」は、過酸化水素処理段を意味する。また、「ｐ」は、過酸化水素を意味し、「ｏ」は、酸素を意味する。そして、「Ｅｏ」は、酸素を併用したアルカリ処理段を意味し、「Ｅｏｐ」は、酸素、過酸化水素を併用したアルカリ処理段を意味する。さらに、「ＺＤ」は、オゾン処理段（Ｚ）と二酸化塩素処理段（Ｄ）との間に洗浄を行うことなく処理を連続することを意味する。その他は、前述したとおりである。
As a bleaching method that does not use molecular chlorine in the first stage, D-Eo-D, D-Eop-D, or D-Eo-DD, D using chlorine dioxide in the first stage -Eop-DD sequence, D-Eo-PD, D-Eop-PD sequence (p or P is hydrogen peroxide), Z-Eop-D, Z-Eo using ozone in the first stage Bleaching by -PD, ZD-Eop-D sequence is generally known.
Here, “Z” means an ozone treatment stage, and “P” means a hydrogen peroxide treatment stage. “P” means hydrogen peroxide, and “o” means oxygen. “Eo” means an alkali treatment stage using oxygen together, and “Eop” means an alkali treatment stage using oxygen and hydrogen peroxide together. Furthermore, “ZD” means that the treatment is continued without performing cleaning between the ozone treatment stage (Z) and the chlorine dioxide treatment stage (D). Others are as described above.
しかしながら、二酸化塩素、オゾンは、従来用いられていた塩素と比べるとヘキセンウロン酸（「ＨｅｘＡ」ということがある）の除去能力が低いために、漂白後のパルプに多量のＨｅｘＡが残存する。この残存ＨｅｘＡがＥＣＦあるいはＴＣＦ漂白パルプの褪色性悪化の原因となる。 However, since chlorine dioxide and ozone have a lower ability to remove hexeneuronic acid (sometimes referred to as “HexA”) than chlorine conventionally used, a large amount of HexA remains in the bleached pulp. This residual HexA causes deterioration of the fading of the ECF or TCF bleached pulp.
ヘキセンウロン酸とは、パルプ中に存在するヘミセルロースであるキシランに結合しているα−グルクロン酸が蒸解工程にて脱メタノールする事により生じる物質である。パルプの白色度への影響は小さいものの、分子内に二重結合を有するため、過マンガン酸カリウムと反応し、Ｋ価あるいはｋａｐｐａ価としてカウントされ、二酸化塩素、オゾン等の漂白剤を消費する。 Hexeneuronic acid is a substance produced by demethanolation of α-glucuronic acid bound to xylan, which is hemicellulose present in pulp, in a cooking process. Although the influence on the whiteness of the pulp is small, it has a double bond in the molecule, so it reacts with potassium permanganate, is counted as a K value or a kappa value, and consumes bleaching agents such as chlorine dioxide and ozone.
また、紙を製造する方法として、硫酸バンドを使用する酸性抄紙と炭酸カルシウムを使用する中性抄紙がある。中性紙もＨｅｘＡ含有量の増大とともに褪色性が悪化するが、その程度は少なく、特に褪色性が悪化する紙は硫酸バンドを使用した酸性紙である。酸性抄紙した紙の褪色性が悪化する原因については、今のところ分かっていないが、ＨｅｘＡの存在、硫酸バンドの使用が原因の一因と考えられている。 In addition, as a method for producing paper, there are acidic paper making using a sulfuric acid band and neutral paper making using calcium carbonate. Neutral paper also deteriorates in color fading with an increase in HexA content, but the degree thereof is small, and in particular, paper whose color fading deteriorates is acidic paper using a sulfuric acid band. The cause of the deterioration of the fading property of the acid paper is not known at present, but the presence of HexA and the use of a sulfuric acid band are considered to be a cause.
一般に、製紙工場では、一連の漂白設備からでてきた無塩素漂白パルプは多数の抄紙機によって、それぞれ中性紙、酸性紙に抄造されている。従って、同一漂白工程からでてきた同じ無塩素漂白パルプを使用して、一方では酸性紙を抄造し、他方では中性紙を抄造している。この場合、中性抄紙で製造した紙の褪色性は問題なくても、酸性抄紙した紙の褪色性が問題となる場合がある。 In general, in a paper mill, chlorine-free bleached pulp from a series of bleaching facilities is made into neutral paper and acidic paper by a number of paper machines. Thus, the same chlorine-free bleached pulp from the same bleaching process is used to make acid paper on the one hand and neutral paper on the other hand. In this case, even if there is no problem with the fading property of the paper produced by neutral papermaking, the fading property of the paper made with acidic paper may become a problem.
この褪色性悪化を改善する方法に、脱ＨｅｘＡ能力のある二酸化塩素あるいはオゾンの使用量を増やしＨｅｘＡを除去する必要がある。しかし、この場合、白色度が上がり過ぎる、漂白コストが大幅に増大するとの問題を生じている。 In order to improve this fading deterioration, it is necessary to remove HexA by increasing the amount of chlorine dioxide or ozone having the ability to remove HexA. However, in this case, there is a problem that the whiteness is excessively increased and the bleaching cost is greatly increased.
二酸化塩素の使用量を抑え褪色を改善する方法として、漂白前処理として高温酸処理を行う方法（特許文献１参照）、また二酸化塩素段を高温下で行う方法（特許文献２参照）が提案されている。しかしながら、いずれの方法も多大なエネルギーコストを要するという問題がある。 As a method for reducing the amount of chlorine dioxide used and improving discoloration, a method of performing high-temperature acid treatment as a pretreatment for bleaching (see Patent Document 1) and a method of performing a chlorine dioxide stage at a high temperature (see Patent Document 2) have been proposed. ing. However, each method has a problem that a large energy cost is required.
オゾンの使用量を抑える方法として、高温酸処理を行った後、オゾン処理、アルカリ抽出処理を行い、さらに二酸化塩素処理を行う方法が提案されている（特許文献３参照）。この方法は初段脱リグニン、粘度低下抑制に関する方法であるが、ＨｅｘＡ除去、褪色性の改善については何ら記載されていない。 As a method for suppressing the amount of ozone used, a method has been proposed in which ozone treatment and alkali extraction treatment are performed after high-temperature acid treatment, and chlorine dioxide treatment is performed (see Patent Document 3). This method relates to the first-stage delignification and viscosity reduction suppression, but does not describe anything about HexA removal and discoloration improvement.
モノ過硫酸を漂白に適用する方法として、モノ過硫酸とオゾンの組み合わせで行う漂白法に関する方法が提案されている（特許文献４参照）。この方法は漂白工程の初段脱リグニンに関する方法であるが、ＨｅｘＡ除去、褪色性の改善、粘度低下抑制効果については何ら記載されていない。 As a method for applying monopersulfuric acid to bleaching, a method relating to a bleaching method in which monopersulfuric acid and ozone are combined has been proposed (see Patent Document 4). This method relates to the first stage delignification in the bleaching step, but nothing is described about HexA removal, fading improvement, and viscosity reduction inhibiting effect.
また、アルカリ酸素漂白後のパルプを無機ペルオキシ酸で処理した後、オゾン処理から始まる多段漂白を行う方法が提案されている（特許文献５参照）。この方法は、モノ過硫酸処理を漂白の初段に導入することによりＨｅｘＡを除去し、褪色性を改善する方法であるが、モノ過硫酸の消費率とヘキセンウロン酸除去・褪色性の改善の関係については何ら記載されていない。 Further, a method has been proposed in which pulp after alkali oxygen bleaching is treated with an inorganic peroxy acid and then subjected to multistage bleaching starting from ozone treatment (see Patent Document 5). This method is a method of removing HexA by introducing monopersulfate treatment at the first stage of bleaching to improve the fading property. The relationship between the consumption rate of monopersulfuric acid and hexeneuronic acid removal / fading property is improved. Is not described at all.
本発明の目的は、製紙用化学パルプの製造で、初段に分子状塩素を用いないＥＣＦ漂白において、漂白コストを削減し、かつパルプ粘度を維持しながら、ＥＣＦ漂白パルプの褪色性を改善することである。さらに、オゾン、二酸化塩素の使用量を削減し、有機塩素化合物の生成を抑制し、より環境に好ましい漂白方法を提供することである。 The purpose of the present invention is to improve the discoloration of ECF bleached pulp while reducing pulping cost and maintaining pulp viscosity in ECF bleaching without molecular chlorine in the first stage in the manufacture of chemical pulp for papermaking. It is. Furthermore, the amount of ozone and chlorine dioxide used is reduced, the formation of organic chlorine compounds is suppressed, and a more preferable bleaching method for the environment is provided.
本発明者らは、上記課題について鋭意検討した結果、蒸解、アルカリ酸素漂白後のパルプに、所定の消費率までモノ過硫酸処理した後、オゾン処理を行うことにより、パルプ粘度を過度に低下させずに褪色性の改善した漂白パルプを製造することができることを見出し、本発明を完成させるに至った。 As a result of intensive studies on the above problems, the inventors of the present invention have reduced pulp viscosity excessively by subjecting pulp after cooking and alkaline oxygen bleaching to monopersulfuric acid treatment up to a predetermined consumption rate, followed by ozone treatment. The present inventors have found that a bleached pulp having improved fading properties can be produced without losing color.
すなわち、本発明はリグノセルロース物質を蒸解して得られる未漂白パルプをアルカリ酸素漂白し、次いでモノ過硫酸を用いる処理段を含む多段漂白処理を行う漂白パルプの製造方法において、モノ過硫酸を用いる処理段に絶乾パルプ質量当たり少なくとも０．０１質量％のモノ過硫酸を添加し、モノ過硫酸の消費率が少なくとも４０％となるようにモノ過硫酸処理を行った後、次いでオゾン処理を行うことを特徴とする漂白パルプの製造方法に関する。 That is, the present invention uses monopersulfuric acid in a method for producing bleached pulp in which unbleached pulp obtained by digesting lignocellulosic material is bleached with alkali oxygen and then subjected to multistage bleaching including a treatment stage using monopersulfuric acid. At least 0.01% by mass of monopersulfuric acid per mass of absolutely dry pulp is added to the treatment stage, the monopersulfuric acid treatment is performed so that the consumption rate of monopersulfuric acid is at least 40%, and then the ozone treatment is performed. The present invention relates to a method for producing bleached pulp.
本発明によれば、蒸解、アルカリ酸素漂白後のパルプにモノ過硫酸を用いて処理を行う方法において、所定の消費率までモノ過硫酸処理した後、オゾン処理を行うことにより、二酸化塩素を増量しなくてもヘキセンウロン酸を効率的に除去することができ、パルプ粘度を過度に低下させずに褪色性を改善できる。 According to the present invention, in a method for treating pulp after bleaching and alkaline oxygen bleaching with monopersulfuric acid, after monopersulfuric acid treatment to a predetermined consumption rate, ozone treatment is performed to increase chlorine dioxide. Even if not, hexeneuronic acid can be efficiently removed, and fading can be improved without excessively reducing pulp viscosity.
本発明で用いられるリグノセルロース物質は、ヘキセンウロン酸を生成するメチルグルクロン酸を多く含有する広葉樹材が好適であるが、針葉樹材でもよく、竹や麻のような非木材と呼ばれるものでもよく、さらにこれらの混合物でもよく、特に限定されるものではない。 The lignocellulosic material used in the present invention is preferably a hardwood material containing a large amount of methylglucuronic acid that generates hexeneuronic acid, but it may be a softwood material, a non-wood material such as bamboo or hemp, These mixtures may be used and are not particularly limited.
本発明に使用されるパルプを得るための蒸解法としては、クラフト蒸解、ポリサルファイド蒸解、ソーダ蒸解、アルカリサルファイト蒸解等の公知の蒸解法を用いることができるが、パルプ品質、エネルギー効率等を考慮すると、クラフト蒸解法、または、ポリサルファイド蒸解が好適に用いられる。 As the cooking method for obtaining the pulp used in the present invention, known cooking methods such as kraft cooking, polysulfide cooking, soda cooking, alkali sulfite cooking, etc. can be used, considering pulp quality, energy efficiency, etc. Then, the kraft cooking method or polysulfide cooking is used suitably.
例えば、広葉樹材１００％のリグノセルロースをクラフト蒸解する場合、クラフト蒸解液の硫化度は５〜７５質量％、好ましくは１５〜４５質量％、有効アルカリ添加率は絶乾木材質量当たり５〜３０質量％、好ましくは１０〜２５質量％、蒸解温度は１３０〜１７０℃である。蒸解方式は、連続蒸解法あるいはバッチ蒸解法のどちらでもよく、連続蒸解釜を用いる場合は、蒸解液を多点で添加する修正蒸解法でもよく、その方式は特に問わない。 For example, when kraft cooking 100% hardwood wood lignocellulose, the kraft cooking liquor has a sulfidity of 5 to 75% by mass, preferably 15 to 45% by mass, and an effective alkali addition rate of 5 to 30% by mass of absolutely dry wood. %, Preferably 10 to 25% by mass, and the cooking temperature is 130 to 170 ° C. The cooking method may be either a continuous cooking method or a batch cooking method, and when a continuous cooking kettle is used, it may be a modified cooking method in which a cooking solution is added at multiple points, and the method is not particularly limited.
蒸解に際して、使用する蒸解液に蒸解助剤として公知の環状ケト化合物、例えばベンゾキノン、ナフトキノン、アントラキノン、アントロン、フェナントロキノン及び前記キノン系化合物のアルキル、アミノ等の核置換体、或いは前記キノン系化合物の還元型であるアントラヒドロキノンのようなヒドロキノン系化合物、さらにはディールスアルダー法によるアントラキノン合成法の中間体として得られる安定な化合物である９，１０−ジケトヒドロアントラセン化合物等から選ばれた１種或いは２種以上が添加されてもよく、その添加率は通常の添加率であり、例えば、木材チップの絶乾質量当たり０．００１〜１．０質量％である。 In cooking, a known cyclic keto compound as a cooking aid in the cooking solution to be used, for example, benzoquinone, naphthoquinone, anthraquinone, anthrone, phenanthroquinone and quinone-based compounds such as alkyl, amino, or the like, or the quinone-based compound One kind selected from hydroquinone compounds such as anthrahydroquinone which is a reduced form of 9,10-diketohydroanthracene compound which is a stable compound obtained as an intermediate of anthraquinone synthesis method by Diels Alder method Or 2 or more types may be added and the addition rate is a normal addition rate, for example, is 0.001-1.0 mass% per the absolute dry mass of a wood chip.
公知の蒸解法により得られた未漂白化学パルプは洗浄、粗選及び精選工程を経て、公知のアルカリ酸素漂白法により脱リグニンされる。本発明に使用されるアルカリ酸素漂白法は、公知の中濃度法あるいは高濃度法がそのまま適用できるが、現在汎用的に用いられているパルプ濃度が８〜１５質量％で行われる中濃度法が好ましい。 The unbleached chemical pulp obtained by a known cooking method is subjected to washing, rough selection and selection processes, followed by delignification by a known alkaline oxygen bleaching method. As the alkaline oxygen bleaching method used in the present invention, a known medium concentration method or high concentration method can be applied as it is, but a medium concentration method in which the pulp concentration currently used for general purposes is 8 to 15% by mass is used. preferable.
前記中濃度法によるアルカリ酸素漂白法において、アルカリとしては苛性ソーダあるいは酸化されたクラフト白液を使用することができ、酸素ガスとしては、深冷分離法からの酸素、ＰＳＡ（Ｐｒｅｓｓｕｒｅ Ｓｗｉｎｇ Ａｄｓｏｒｐｔｉｏｎ）からの酸素、ＶＳＡ（Ｖａｃｕｕｍ Ｓｗｉｎｇ Ａｄｓｏｒｐｔｉｏｎ）からの酸素等が使用できる。
前記酸素ガスとアルカリは中濃度ミキサーにおいて中濃度のパルプスラリーに添加され混合が十分に行われた後、加圧下でパルプ、酸素及びアルカリの混合物を一定時間保持できる反応塔へ送られ、脱リグニンされる。酸素ガスの添加率は、絶乾（ＢＤ：ｂｏｎｅ ｄｒｙ）パルプ質量当たり０．５〜３質量％、アルカリ添加率は０．５〜４質量％、反応温度は８０〜１２０℃、反応時間は１５〜１００分、パルプ濃度は８〜１５質量％が好適であり、この他の条件は公知のものが適用できる。本発明では、アルカリ酸素漂白工程において、上記アルカリ酸素漂白を連続して複数回行い、できる限り脱リグニンを進め、重金属の含有量を減らしておくのが好ましい実施形態である。アルカリ酸素漂白が施されたパルプは次いで洗浄工程へ送られる。洗浄後のパルプは、多段漂白処理工程へ送られる。
In the alkali oxygen bleaching method by the medium concentration method, caustic soda or oxidized kraft white liquor can be used as the alkali. As the oxygen gas, oxygen from a cryogenic separation method, PSA (Pressure Swing Adsorption) Oxygen, oxygen from VSA (Vacuum Swing Adsorption), etc. can be used.
The oxygen gas and alkali are added to a medium-concentration pulp slurry in a medium-concentration mixer and mixed sufficiently, and then sent to a reaction tower capable of holding a mixture of pulp, oxygen, and alkali for a certain period of time under pressure, and delignified. Is done. The oxygen gas addition rate is 0.5 to 3% by mass per BD (bone dry) pulp mass, the alkali addition rate is 0.5 to 4% by mass, the reaction temperature is 80 to 120 ° C., and the reaction time is 15%. The pulp concentration is suitably 8 to 15% by mass for -100 minutes, and other known conditions can be applied. In the present invention, in the alkaline oxygen bleaching step, it is a preferred embodiment that the alkali oxygen bleaching is continuously performed a plurality of times, delignification is advanced as much as possible, and the heavy metal content is reduced. The pulp that has been subjected to alkaline oxygen bleaching is then sent to a washing step. The pulp after washing is sent to a multistage bleaching process.
本発明のモノ過硫酸処理を用いる処理段を含む多段漂白処理としては、例えば、ＰｘＺＤ−Ｅｐ−Ｄ、ＰｘＺＤ−Ｅｏｐ−Ｄ、ＰｘＺＤ−Ｅｐ−Ｐ−Ｄ、ＰｘＺＤ−Ｅｏｐ−Ｐ−Ｄ、ＰｘＺＤ−Ｅｐ−Ｄ−Ｄ、ＰｘＺＤ−Ｅｏｐ−Ｄ−Ｄ、ＰｘＺＤ−Ｅｐ−Ｄ−Ｐ、ＰｘＺＤ−Ｅｏｐ−Ｄ−Ｐ、Ｐｘ−ＺＤ−Ｅｐ−Ｄ、Ｐｘ−ＺＤ−Ｅｏｐ−Ｄ、Ｐｘ−ＺＤ−Ｅｐ−Ｐ−Ｄ、Ｐｘ−ＺＤ−Ｅｏｐ−Ｐ−Ｄ、Ｐｘ−ＺＤ−Ｅｐ−Ｄ−Ｄ、Ｐｘ−ＺＤ−Ｅｏｐ−Ｄ−Ｄ、Ｐｘ−ＺＤ−Ｅｐ−Ｄ−Ｐ、Ｐｘ−ＺＤ−Ｅｏｐ−Ｄ−Ｐ、ＰｘＺ−Ｄ−Ｅｐ−Ｄ、ＰｘＺ−Ｄ−Ｅｏｐ−Ｄ、ＰｘＺ−Ｄ−Ｅｐ−Ｐ−Ｄ、ＰｘＺ−Ｄ−Ｅｏｐ−Ｐ−Ｄ、ＰｘＺ−Ｄ−Ｅｐ−Ｄ−Ｄ、ＰｘＺ−Ｄ−Ｅｏｐ−Ｄ−Ｄ、ＰｘＺ−Ｄ−Ｅｐ−Ｄ−Ｐ、ＰｘＺ−Ｄ−Ｅｏｐ−Ｄ−Ｐ、Ｐｘ−Ｚ−Ｄ−Ｅｐ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｏｐ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｐ−Ｐ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｏｐ−Ｐ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｐ−Ｄ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｏｐ−Ｄ−Ｄ、Ｐｘ−Ｚ−Ｄ−Ｅｐ−Ｄ−Ｐ、Ｐｘ−Ｚ−Ｄ−Ｅｏｐ−Ｄ−Ｐ、ＰｘＺ−Ｅｐ−Ｄ、ＰｘＺ−Ｅｏｐ−Ｄ、Ｐｘ−Ｚ−Ｅｐ−Ｄ、Ｐｘ−Ｚ−Ｅｏｐ−Ｄ、ＰｘＺ−Ｅｐ−Ｐ−Ｄ、ＰｘＺ−Ｅｏｐ−Ｐ−Ｄ、Ｐｘ−Ｚ−Ｅｐ−Ｐ−Ｄ、Ｐｘ−Ｚ−Ｅｏｐ−Ｐ−Ｄ、ＰｘＺ−Ｅｐ−Ｄ−Ｄ、ＰｘＺ−Ｅｏｐ−Ｄ−Ｄ、Ｐｘ−Ｚ−Ｅｐ−Ｄ−Ｄ、Ｐｘ−Ｚ−Ｅｏｐ−Ｄ−Ｄ、Ｄ−Ｅｐ−ＰｘＺＤ、Ｄ−Ｅｏｐ−ＰｘＺＤ、Ｄ−Ｅｐ−Ｐ−ＰｘＺＤ、Ｄ−Ｅｏｐ−Ｐ−ＰｘＺＤ、Ｄ−Ｅｐ−Ｄ−ＰｘＺＤ、Ｄ−Ｅｏｐ−Ｄ−ＰｘＺＤ、Ｄ−Ｅｐ−Ｐｘ−ＺＤ、Ｄ−Ｅｏｐ−Ｐｘ−ＺＤ、Ｄ−Ｅｐ−Ｐ−Ｐｘ−ＺＤ、Ｄ−Ｅｏｐ−Ｐ−Ｐｘ−ＺＤ、Ｄ−Ｅｐ−Ｄ−Ｐｘ−ＺＤ、Ｄ−Ｅｏｐ−Ｄ−Ｐｘ−ＺＤ、Ｄ−Ｅｐ−ＰｘＺ−Ｄ、Ｄ−Ｅｏｐ−ＰｘＺ−Ｄ、Ｄ−Ｅｐ−Ｐ−ＰｘＺ−Ｄ、Ｄ−Ｅｏｐ−Ｐ−ＰｘＺ−Ｄ、Ｄ−Ｅｐ−Ｄ−ＰｘＺ−Ｄ、Ｄ−Ｅｏｐ−Ｄ−ＰｘＺ−Ｄ、Ｄ−Ｅｐ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｏｐ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｐ−Ｐ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｏｐ−Ｐ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｐ−Ｄ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｏｐ−Ｄ−Ｐｘ−Ｚ−Ｄ、Ｄ−Ｅｐ−Ｄ−ＰｘＺ、Ｄ−Ｅｏｐ−Ｄ−ＰｘＺ、Ｄ−Ｅｐ−Ｐ−ＰｘＺ、Ｄ−Ｅｏｐ−Ｐ−ＰｘＺ、Ｄ−Ｅｐ−Ｄ−Ｐｘ−Ｚ、Ｄ−Ｅｏｐ−Ｄ−Ｐｘ−Ｚ、Ｄ−Ｅｐ−Ｐ−Ｐｘ−Ｚ、Ｄ−Ｅｏｐ−Ｐ−Ｐｘ−Ｚのようなオゾンと二酸化塩素を使用したＥＣＦシークエンスが挙げられるが、これらのシーケンスに限定されるものではない。
ここで、「Ｐｘ」はモノ過硫酸処理段を意味し、「ＰｘＺ」は、モノ過硫酸処理段（Ｐｘ）とオゾン処理段（Ｚ）との間に洗浄を行うことなく処理を連続することを意味する。さらに、「ＺＤ」は、オゾン処理段（Ｚ）と二酸化塩素処理段（Ｄ）との間に洗浄を行うことなく処理を連続することを意味する。
モノ過硫酸処理は、モノ過硫酸の添加率あたりのパルプの褪色性改善効果がより大きい点から多段漂白処理の初段に行うのが好ましい実施形態である。
Examples of the multi-stage bleaching process including the process stage using the monopersulfuric acid process of the present invention include PxZD-Ep-D, PxZD-Eop-D, PxZD-Ep-P-D, PxZD-Eop-P-D, and PxZD. -Ep-DD, PxZD-Eop-DD, PxZD-Ep-DP, PxZD-Eop-DP, Px-ZD-Ep-D, Px-ZD-Eop-D, Px-ZD -Ep-P-D, Px-ZD-Eop-P-D, Px-ZD-Ep-D-D, Px-ZD-Eop-DD, Px-ZD-Ep-DP, Px-ZD -Eop-DP, PxZ-D-Ep-D, PxZ-D-Eop-D, PxZ-D-Ep-P-D, PxZ-D-Eop-P-D, PxZ-D-Ep-D -D, PxZ-D-Eop-DD, PxZ-D-Ep-DP, PxZ-DE p-D-P, Px-Z-D-Ep-D, Px-Z-D-Eop-D, Px-Z-D-Ep-P-D, Px-Z-D-Eop-P-D, Px-Z-D-Ep-D-D, Px-Z-D-Eop-D-D, Px-Z-D-Ep-DP, Px-Z-D-Eop-DP, PxZ- Ep-D, PxZ-Eop-D, Px-Z-Ep-D, Px-Z-Eop-D, PxZ-Ep-P-D, PxZ-Eop-P-D, Px-Z-Ep-P- D, Px-Z-Eop-PD, PxZ-Ep-DD, PxZ-Eop-DD, Px-Z-Ep-DD, Px-Z-Eop-DD, D- Ep-PxZD, D-Eop-PxZD, D-Ep-P-PxZD, D-Eop-P-PxZD, D-Ep-D-PxZD, D-Eop-D-PxZD, D-Ep-Px ZD, D-Eop-Px-ZD, D-Ep-P-Px-ZD, D-Eop-P-Px-ZD, D-Ep-D-Px-ZD, D-Eop-D-Px-ZD, D-Ep-PxZ-D, D-Eop-PxZ-D, D-Ep-P-PxZ-D, D-Eop-P-PxZ-D, D-Ep-D-PxZ-D, D-Eop- D-PxZ-D, D-Ep-Px-Z-D, D-Eop-Px-Z-D, D-Ep-P-Px-Z-D, D-Eop-P-Px-Z-D, D-Ep-D-Px-ZD, D-Eop-D-Px-ZD, D-Ep-D-PxZ, D-Eop-D-PxZ, D-Ep-P-PxZ, D- Ozone such as Eop-P-PxZ, D-Ep-D-Px-Z, D-Eop-D-Px-Z, D-Ep-P-Px-Z, D-Eop-P-Px-Z two Examples include ECF sequences using chlorine oxide, but are not limited to these sequences.
Here, “Px” means a monopersulfate treatment stage, and “PxZ” means that the treatment is continued between the monopersulfate treatment stage (Px) and the ozone treatment stage (Z) without washing. Means. Furthermore, “ZD” means that the treatment is continued without performing cleaning between the ozone treatment stage (Z) and the chlorine dioxide treatment stage (D).
The monopersulfuric acid treatment is preferably performed in the first stage of the multistage bleaching treatment because the effect of improving the discoloration of the pulp per addition ratio of monopersulfuric acid is greater.
本発明で使用されるモノ過硫酸（以下、ＭＰＳということがある）は、ペルオキシ二硫酸を加水分解して製造することもできるし、過酸化水素と硫酸を任意の割合で混合して製造することもできるが、その製造方法については特に限定するものではない。また、モノ過硫酸の複塩（２ＫＨＳＯ５・ＫＨＳＯ４・Ｋ２ＳＯ４）であるオキソンのようなものを使用することもできる。ただし、経済性を考慮すると、高濃度の過酸化水素と高濃度の硫酸を混合してモノ過硫酸を製造し、使用するのが好ましい実施形態である。 Monopersulfuric acid (hereinafter sometimes referred to as MPS) used in the present invention can be produced by hydrolyzing peroxydisulfuric acid, or by mixing hydrogen peroxide and sulfuric acid in an arbitrary ratio. However, the production method is not particularly limited. It is also possible to use something like oxone is a monopersulfate double salt (2KHSO 5 · KHSO 4 · K 2 SO 4). However, in consideration of economy, it is a preferred embodiment to produce and use monopersulfuric acid by mixing high concentration hydrogen peroxide and high concentration sulfuric acid.
高濃度の過酸化水素と高濃度の硫酸を混合してモノ過硫酸を製造する方法としては、２０質量％〜７０質量％、好ましくは３５質量％〜６０質量％濃度の過酸化水素水に８０質量％〜９８％質量％、好ましくは９３質量％〜９８質量％の濃硫酸を滴下、混合する方法が好適である。前記硫酸と過酸化水素の混合モル比は好ましくは１：１〜５：１であり、さらに好ましくは２：１〜４：１である。過酸化水素、硫酸共に、濃度の低いものを用いるとモノ過硫酸の製造効率が低下するため適さない。また、濃度が高すぎると、発火等の危険性が大きくなるため適さない。さらに、硫酸と過酸化水素の混合モル比が１：１〜５：１から外れる場合にもモノ過硫酸の製造効率が低下するために好ましくない。 As a method for producing monopersulfuric acid by mixing high-concentration hydrogen peroxide and high-concentration sulfuric acid, 80% hydrogen peroxide solution having a concentration of 20% by mass to 70% by mass, preferably 35% by mass to 60% by mass is used. A method of dropping and mixing concentrated sulfuric acid in an amount of mass% to 98% by mass, preferably 93 mass% to 98 mass% is suitable. The mixing molar ratio of the sulfuric acid and hydrogen peroxide is preferably 1: 1 to 5: 1, more preferably 2: 1 to 4: 1. If both hydrogen peroxide and sulfuric acid have low concentrations, the production efficiency of monopersulfuric acid decreases, which is not suitable. On the other hand, if the concentration is too high, the risk of ignition and the like increases, which is not suitable. Furthermore, when the mixing molar ratio of sulfuric acid and hydrogen peroxide deviates from 1: 1 to 5: 1, it is not preferable because the production efficiency of monopersulfuric acid is lowered.
本発明では、モノ過硫酸を用いる処理段にモノ過硫酸を添加し、所定の消費率までモノ過硫酸処理する。本発明のモノ過硫酸処理条件を以下に示す。モノ過硫酸添加率は、絶乾パルプ質量当たり少なくとも０．０１質量％である。処理ｐＨは好ましくは１．５〜６、より好ましくは２〜４である。モノ過硫酸添加率が０．０１質量％未満ではヘキセンウロン酸の低減効果が不十分である。モノ過硫酸添加率が高くなるに従い、パルプスラリーのｐＨが低下する傾向を示し、ｐＨ１．５未満となるとパルプ粘度が著しく低下する怖れがある。このため、公知のアルカリおよび酸を使用することで前記ｐＨ範囲にｐＨ調整することでこれらの問題を回避できるが、経済性を考慮するとモノ過硫酸添加率としては、好ましくは０．０１〜２質量％、より好ましくは０．１〜１質量％が好適である。処理温度は２０〜１００℃が好ましく、４０〜９０℃がさらに好ましい。パルプスラリー中のパルプ濃度に関しては特に限定されるものではないが、操作性の点から好適には８〜１５質量％で行われる。処理時間は、添加したモノ過硫酸の４０％以上が消費されるように決定される。 In the present invention, monopersulfuric acid is added to a treatment stage using monopersulfuric acid, and monopersulfuric acid treatment is performed up to a predetermined consumption rate. The monopersulfate treatment conditions of the present invention are shown below. The monopersulfuric acid addition rate is at least 0.01% by mass per mass of dry pulp. The treatment pH is preferably 1.5 to 6, more preferably 2 to 4. When the monopersulfuric acid addition rate is less than 0.01% by mass, the effect of reducing hexeneuronic acid is insufficient. As the monopersulfuric acid addition rate increases, the pH of the pulp slurry tends to decrease. When the pH is less than 1.5, the pulp viscosity may be significantly decreased. For this reason, these problems can be avoided by adjusting the pH to the above-mentioned pH range by using a known alkali and acid, but considering the economic efficiency, the monopersulfuric acid addition rate is preferably 0.01-2. The mass%, more preferably 0.1-1 mass% is suitable. The processing temperature is preferably 20 to 100 ° C, more preferably 40 to 90 ° C. Although it does not specifically limit regarding the pulp density | concentration in a pulp slurry, It is 8-15 mass% suitably from the point of operativity. The treatment time is determined so that 40% or more of the added monopersulfuric acid is consumed.
本発明のパルプは、添加したモノ過硫酸の少なくとも４０％が消費された後に、引き続きオゾン処理が施される。特にモノ過硫酸の消費率が４０〜６０％になった時点でオゾン処理に移行するのが好ましい。モノ過硫酸の消費率が４０〜６０％の範囲であるときに、オゾン処理に移ると、ヘキセンウロン酸を効率的に除去できるだけでなく、パルプの粘度低下を抑制できるために好ましい。 The pulp of the present invention is subsequently subjected to ozone treatment after at least 40% of the added monopersulfuric acid has been consumed. In particular, it is preferable to shift to ozone treatment when the consumption rate of monopersulfuric acid reaches 40 to 60%. When the consumption rate of monopersulfuric acid is in the range of 40 to 60%, it is preferable to shift to ozone treatment because not only can hexeneuronic acid be efficiently removed, but also a decrease in pulp viscosity can be suppressed.
更に粘度低下を抑制するために、モノ過硫酸処理時にキレート剤、多価カルボン酸、またはこれらの混合物を併用使用してもよい。 Further, in order to suppress a decrease in viscosity, a chelating agent, a polyvalent carboxylic acid, or a mixture thereof may be used in combination during monopersulfuric acid treatment.
本発明では、モノ過硫酸処理を行った後、次いでオゾン処理を行う。モノ過硫酸処理からオゾン処理に移行する際には、モノ過硫酸処理を行ったパルプを水で洗浄をしてもしなくてもよいが、モノ過硫酸処理を行った後、パルプを洗浄しないでオゾン処理を行う方が、オゾン処理後のヘキセンウロン酸濃度を小さくできるので好ましい。 In the present invention, after the monopersulfuric acid treatment, the ozone treatment is then performed. When shifting from monopersulfuric acid treatment to ozone treatment, pulp that has undergone monopersulfate treatment may or may not be washed with water, but after performing monopersulfate treatment, do not wash the pulp. The ozone treatment is preferable because the hexeneuronic acid concentration after the ozone treatment can be reduced.
モノ過硫酸処理に次いで実施されるオゾン処理の条件としては、オゾン添加率は絶乾パルプ質量当たり好ましくは０．０５〜２質量％、より好ましくは０．１％〜１．０質量％である。処理ｐＨは好ましくは１〜７、より好ましくは２〜５、さらに好ましくは２．５〜４であり、ｐＨ調整用に公知のアルカリおよび酸を使用することができる。処理時間は数十秒〜数十分である。処理温度は好ましくは２０〜１００℃、より好ましくは４０〜８０℃である。パルプスラリー中のパルプ濃度に関しては特に限定されるものではないが、３０％程度の高濃度、あるいは１０％程度の中濃度のいずれでも行うことができるが、操作性の点から好適には８〜１５質量％で行われる。 As conditions for the ozone treatment that is performed after the monopersulfuric acid treatment, the ozone addition rate is preferably 0.05 to 2% by mass, more preferably 0.1% to 1.0% by mass, based on the mass of the absolutely dry pulp. . The treatment pH is preferably 1 to 7, more preferably 2 to 5, and still more preferably 2.5 to 4. Known alkalis and acids can be used for pH adjustment. The processing time is several tens of seconds to several tens of minutes. The treatment temperature is preferably 20 to 100 ° C, more preferably 40 to 80 ° C. Although it does not specifically limit regarding the pulp density | concentration in a pulp slurry, Although it can carry out by any of the high density | concentration of about 30%, or the medium density | concentration of about 10%, From the point of operativity, 8- Performed at 15% by weight.
本発明では、オゾン処理後のパルプは、洗浄せずに二酸化塩素処理を行うことが好ましい形態である。二酸化塩素処理段の条件としては、二酸化塩素添加率は絶乾パルプ質量当たり好ましくは０．２％〜２．０％である。処理ｐＨは好ましくは１．５〜６、より好ましくは２〜４であり、ｐＨ調整用に公知のアルカリおよび酸を使用することができる。処理時間は好ましくは１分〜５時間、より好ましくは１０分〜１８０分である。処理温度は好ましくは２０℃〜１００℃、より好ましくは４０℃〜９０℃である。パルプスラリー中のパルプ濃度に関しては特に限定されるものではないが、操作性の点から好適には８〜１５質量％で行われる。 In the present invention, the ozone-treated pulp is preferably subjected to chlorine dioxide treatment without washing. As conditions for the chlorine dioxide treatment stage, the chlorine dioxide addition rate is preferably 0.2% to 2.0% per mass of the dry pulp. The treatment pH is preferably 1.5 to 6, more preferably 2 to 4, and known alkalis and acids can be used for pH adjustment. The treatment time is preferably 1 minute to 5 hours, more preferably 10 minutes to 180 minutes. The treatment temperature is preferably 20 ° C to 100 ° C, more preferably 40 ° C to 90 ° C. Although it does not specifically limit regarding the pulp density | concentration in a pulp slurry, It is 8-15 mass% suitably from the point of operativity.
モノ過硫酸処理を用いる処理段を含む多段漂白処理の一例としてＰｘＺＤ−Ｅｏｐ−Ｄについて、この漂白方法のＺＤ段以降の漂白方法について説明する。 As an example of multi-stage bleaching including a processing stage using monopersulfuric acid treatment, PxZD-Eop-D will be described with respect to the bleaching method after the ZD stage of this bleaching method.
ＰｘＺＤ処理されたパルプは洗浄工程へ移送される。洗浄方法としては、一般的な洗浄方法を用いることができ、パルプ中の残存薬液、ＣＯＤ等が効率よく洗浄できればいずれの洗浄機でもよく、例えば、ディヒュージョンタイプ、プレスタイプ、ワイヤ−タイプの洗浄機が使用できる。 The PxZD treated pulp is transferred to the washing process. As a cleaning method, a general cleaning method can be used, and any cleaning machine may be used as long as the residual chemical solution in the pulp, COD, and the like can be efficiently cleaned, for example, a diffusion type, a press type, and a wire type cleaning. The machine can be used.
洗浄されたパルプはアルカリ／酸素／過酸化水素処理工程（Ｅｏｐ）に送られる。一般にアルカリ量としては、絶乾パルプ質量あたり０．５〜３．０質量％であり、酸素量としては、０．０５〜０．３質量％であり、過酸化水素量量としては、絶乾パルプ質量あたり０．０５〜１．０質量％である。処理ｐＨは漂白後のｐＨとして好ましくは１０〜１２であり、より好ましくは１１.０〜１１．７である。処理時間は好ましくは１５分〜５時間、より好ましくは３０分〜３時間である。処理温度は、好ましくは２０〜１００℃、より好ましくは５０〜９０℃である。パルプスラリー中のパルプ濃度に関しては特に限定されるものではないが、操作性の点から好適には８〜１５質量％で行われる。アルカリ／酸素／過酸化水素処理されたパルプは、洗浄工程へ移送される。洗浄方法としては、パルプ中の残存薬液、ＣＯＤ等が効率よく洗浄できればいずれの方法でもよい。 The washed pulp is sent to an alkali / oxygen / hydrogen peroxide treatment step (Eop). In general, the alkali amount is 0.5 to 3.0% by mass per the dry pulp mass, the oxygen amount is 0.05 to 0.3% by mass, and the hydrogen peroxide amount is absolutely dry. It is 0.05-1.0 mass% per pulp mass. The treatment pH is preferably 10 to 12, more preferably 11.0 to 11.7 as the pH after bleaching. The treatment time is preferably 15 minutes to 5 hours, more preferably 30 minutes to 3 hours. Processing temperature becomes like this. Preferably it is 20-100 degreeC, More preferably, it is 50-90 degreeC. Although it does not specifically limit regarding the pulp density | concentration in a pulp slurry, It is 8-15 mass% suitably from the point of operativity. The alkali / oxygen / hydrogen peroxide treated pulp is transferred to a washing step. As a washing method, any method may be used as long as the residual chemical solution, COD, etc. in the pulp can be washed efficiently.
洗浄されたパルプは、最終段の二酸化塩素処理段へ送られる。この処理段の二酸化塩素添加率は、絶乾パルプ質量当たり好ましくは０．０５〜１．０質量％であり、より好ましくは０．１〜０．５質量％である。処理ｐＨは好ましくは１．５〜６、より好ましくは２〜６、さらに好ましくは４〜６である。ｐＨ調整用に公知のアルカリおよび酸を使用することができる。処理時間は好ましくは１５分〜５時間、より好ましくは３０分〜１８０分である。処理温度は好ましくは２０℃〜１００℃、より好ましくは５０℃〜８０℃である。パルプスラリー中のパルプ濃度に関しては特に限定されるものではないが、操作性の点から好適には８〜１５質量％で行われる。 The washed pulp is sent to the final chlorine dioxide treatment stage. The chlorine dioxide addition rate in this treatment stage is preferably 0.05 to 1.0% by mass, more preferably 0.1 to 0.5% by mass, per mass of the absolutely dry pulp. Processing pH becomes like this. Preferably it is 1.5-6, More preferably, it is 2-6, More preferably, it is 4-6. Known alkalis and acids can be used for pH adjustment. The treatment time is preferably 15 minutes to 5 hours, more preferably 30 minutes to 180 minutes. The treatment temperature is preferably 20 ° C to 100 ° C, more preferably 50 ° C to 80 ° C. Although it does not specifically limit regarding the pulp density | concentration in a pulp slurry, It is 8-15 mass% suitably from the point of operativity.
上記多段漂白処理シーケンスで漂白された完成パルプの白色度は７０〜８９％であることが好ましい。また、パルプの褪色度の指標になるＫ価、ヘキセンウロン酸残量は低ければ低いほど好ましいが、そのためには多量の漂白薬剤を必要とし、パルプ粘度低下、コストアップの問題が生じる。そこで、パルプの褪色問題と漂白コストの両方を解決できる本発明法に好適な完成パルプ物性としては、Ｋ価１．５以下、ヘキセンウロン酸残量１０μｍｏｌ／パルプｇ以下である。 The whiteness of the finished pulp bleached by the multi-stage bleaching treatment sequence is preferably 70 to 89%. Further, the lower the K value and the remaining amount of hexeneuronic acid, which are indicators of the color fading of the pulp, are preferable. However, a large amount of bleaching agent is required for this purpose, resulting in a decrease in pulp viscosity and an increase in cost. Therefore, the finished pulp physical properties suitable for the method of the present invention that can solve both the fading problem and the bleaching cost of the pulp are a K value of 1.5 or less and a hexeneuronic acid residual amount of 10 μmol / pulp g or less.
上記の多段漂白処理シーケンスにより所望の白色度、Ｋ価、ヘキセンウロン酸残量となるように漂白された完成パルプは、貯槽工程を経て抄紙工程へ送られる。 The finished pulp bleached by the above-mentioned multi-stage bleaching treatment sequence so as to have desired whiteness, K value, and hexeneuronic acid remaining amount is sent to the papermaking process through the storage tank process.
本発明で用いるｐＨ調整用の酸としては、特に限定されるものではないが、塩酸、硫酸、亜硫酸、硝酸、蟻酸、シュウ酸等の無機、有機の酸が挙げられる。ｐＨ調整用のアルカリとしては、特に限定されるものではないが、苛性ソーダ、苛性カリウム、炭酸ソーダ、炭酸カルシウム、アンモニア、アミン類等の無機、有機のアルカリが挙げられる。 The acid for adjusting the pH used in the present invention is not particularly limited, and examples thereof include inorganic and organic acids such as hydrochloric acid, sulfuric acid, sulfurous acid, nitric acid, formic acid and oxalic acid. The alkali for pH adjustment is not particularly limited, and examples thereof include inorganic and organic alkalis such as caustic soda, caustic potassium, sodium carbonate, calcium carbonate, ammonia and amines.
以下に実施例及び比較例を挙げて本発明をより具体的に説明するが、勿論本発明はこれらの実施例に限定されるものではない。以下に示す実施例、比較例においては、特に示さない限り、モノ過硫酸の製造、モノ過硫酸の消費率の測定法、パルプの過マンガン酸カリウム価（Ｋ価）の測定、パルプ粘度の測定、パルプ白色度の測定、パルプの褪色性評価、パルプのヘキセンウロン酸の測定、各段の漂白条件はそれぞれ以下の方法・条件で行った。なお、実施例及び比較例における薬品の添加率は絶乾パルプ質量当たりの質量％を示す。 Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to these examples. In the following examples and comparative examples, unless otherwise indicated, production of monopersulfuric acid, measurement method of monopersulfate consumption rate, measurement of potassium permanganate value (K value) of pulp, measurement of pulp viscosity Pulp whiteness measurement, pulp fading evaluation, pulp hexeneuronic acid measurement, and bleaching conditions for each stage were carried out by the following methods and conditions, respectively. In addition, the addition rate of the chemical | medical agent in an Example and a comparative example shows the mass% per the absolute dry pulp mass.
１．モノ過硫酸（ＭＰＳ）の製造
工業用の４５質量％過酸化水素水４４２ｇ中に工業用の９５質量％硫酸１８１０ｇを添加し、モノ過硫酸を製造した。製造したモノ過硫酸の濃度は、１８.２質量％であった。
1. Production of monopersulfuric acid (MPS) 1844 g of industrial 95 mass% sulfuric acid was added to 442 g of 45 mass% aqueous hydrogen peroxide for industrial use to produce monopersulfuric acid. The concentration of the produced monopersulfuric acid was 18.2% by mass.
２．モノ過硫酸（ＭＰＳ）の消費率の測定法
モノ過硫酸処理後のパルプを絶乾パルプ質量当たり２０ｇ取り出し、綿布を用いて５０ｍｌのろ液を採取した。ろ液を２５ｍｌずつ分割し、一方を０．０２５ｍｏｌ／Ｌの硫酸セリウム（ＩＶ）溶液を用いて、もう一方を０．１ｍｏｌ／Ｌのチオ硫酸ナトリウム溶液を用いて酸化還元滴定を行った。０．１ｍｏｌ／Ｌのチオ硫酸ナトリウム滴定で測定した、ろ液中の全過酸化物の濃度から、０．０２５ｍｏｌ／Ｌの硫酸セリウム滴定で測定した、過酸化水素濃度を差し引き、ろ液中のＭＰＳ濃度を求め、パルプ質量当たりの残存ＭＰＳ濃度を算出した。ＭＰＳの消費率は、下式により算出した。
ＭＰＳ消費率（％）＝１００−{（残存ＭＰＳ濃度／添加したＭＰＳ濃度）×１００}
2. Method for Measuring Monopersulfuric Acid (MPS) Consumption Rate The pulp after monopersulfuric acid treatment was taken out in an amount of 20 g per anomalous pulp mass, and 50 ml of filtrate was collected using a cotton cloth. The filtrate was divided into 25 ml portions, and one was subjected to redox titration using a 0.025 mol / L cerium (IV) sulfate solution and the other using a 0.1 mol / L sodium thiosulfate solution. The hydrogen peroxide concentration measured by 0.025 mol / L cerium sulfate titration was subtracted from the concentration of total peroxide in the filtrate measured by 0.1 mol / L sodium thiosulfate titration. The MPS concentration was determined, and the residual MPS concentration per pulp mass was calculated. The MPS consumption rate was calculated by the following equation.
MPS consumption rate (%) = 100 − {(residual MPS concentration / added MPS concentration) × 100}
３．パルプの過マンガン酸カリウム価（Ｋ価）の測定
過マンガン酸カリウム価の測定は、ＴＡＰＰＩ ＵＭ ２５３に準じて行った。
3. Measurement of potassium permanganate value (K value) of pulp The measurement of potassium permanganate value was performed according to TAPPI UM253.
４．パルプ粘度の測定
パルプ粘度の測定は、Ｊ．ＴＡＰＰＩ Ｎｏ．４４法に準じて行った。
4). Measurement of Pulp Viscosity TAPPI No. Performed according to Method 44.
５．パルプ白色度の測定
漂白パルプを離解後、ＩＳＯ３６８８−１９７７に従って坪量４００ｇ／ｍ２のシートを２枚作製し、ＪＩＳ Ｐ ８１４８に従ってパルプの白色度を測定した。
5. Measurement of Pulp Whiteness After the bleached pulp was disaggregated, two sheets having a basis weight of 400 g / m 2 were prepared according to ISO 3688-1977, and the whiteness of the pulp was measured according to JIS P 8148.
６．パルプの褪色性評価
漂白パルプを離解後、硫酸アルミニウムを加え、ｐＨ４．５に調整した後、坪量４００ｇ／ｍ２のシート２枚を作製し、送風乾燥機にて乾燥させた。このシートを８０℃、相対湿度６５％の条件下で、２４時間静置しさせ、褪色前後の白色度から下式に従いＰＣ価を算出し、評価した。
ＰＣ価＝｛（１−褪色後白色度）２／（２×褪色後白色度）−（１−褪色前白色度）２／（２×褪色前白色度）｝×１００
6). Evaluation of color fading of pulp After bleaching the bleached pulp, aluminum sulfate was added to adjust the pH to 4.5, and then two sheets with a basis weight of 400 g / m 2 were prepared and dried with a blow dryer. This sheet was allowed to stand for 24 hours under the conditions of 80 ° C. and relative humidity of 65%, and the PC value was calculated from the whiteness before and after discoloration according to the following formula and evaluated.
PC value = {(1−whiteness after fading) 2 / (2 × whiteness after fading) − (1−whiteness before fading) 2 / (2 × whiteness before fading)} × 100
７．パルプのヘキセンウロン酸量の測定
完全洗浄したパルプを絶乾質量で０．８ｇ精秤した。このパルプを耐圧容器に入れ純水８０ｍｌを加えた後、蟻酸を加えｐＨ３に調整した。この耐圧容器をオーブンに入れ、１２０℃で４時間処理し、ヘキセンウロン酸を酸加水分解した。処理後ろ過を行い、濾別された溶液中に存在するヘキセンウロン酸の酸加水分解物である２−フランカルボン酸と５−カルボキシ−２−フランアルデヒドをＨＰＬＣにて定量し、そのモル量の合計からヘキセンウロン酸量を求めた。
7). Measurement of hexeneuronic acid content of pulp Weighed 0.8 g of the completely washed pulp in an absolutely dry mass. The pulp was placed in a pressure vessel and 80 ml of pure water was added, and then formic acid was added to adjust the pH to 3. The pressure vessel was put in an oven and treated at 120 ° C. for 4 hours to hydrolyze hexeneuronic acid. After the treatment, filtration was performed, and 2-furancarboxylic acid and 5-carboxy-2-furanaldehyde, which are acid hydrolysates of hexeneuronic acid present in the solution separated by filtration, were quantified by HPLC, and the total of the molar amounts. From this, the amount of hexeneuronic acid was determined.
８．使用未晒パルプ物性
未晒パルプ：アルカリ酸素漂白後パルプ
白色度：５２．７％、Ｋ価：６．７、粘度：２ １．３ｍＰａ・ｓ、
ＨｅｘＡ：３９．９μmol／パルプｇ
8). Unbleached pulp properties Unbleached pulp: Alkali oxygen bleached pulp Whiteness: 52.7%, K value: 6.7, Viscosity: 2 1.3 mPa · s,
HexA: 39.9 μmol / pulp g
９．各段の漂白条件
・Ｐｘ段：ＰＣ（パルプ濃度）１０％、温度６０℃、時間１〜１２０分
・Ｚ段：ＰＣ（パルプ濃度）１０％、温度６０℃、時間３分
・Ｄ０段：ＰＣ（パルプ濃度）１０％、温度６０℃、時間３０分
・Ｅｏｐ段：ＰＣ（パルプ濃度）１０％、温度６０℃、時間１２０分
・Ｄ１段：ＰＣ（パルプ濃度）１０％、温度７０℃、時間１８０分
・各段の洗浄条件：洗浄率９０％（漂白後パルプ濃度２．５％に中空糸濾過水で希釈し、次いでパルプ濃度２０％に脱水した）
9. Bleaching conditions for each stage Px stage: PC (pulp concentration) 10%, temperature 60 ° C., time 1 to 120 minutes Z stage: PC (pulp concentration) 10%, temperature 60 ° C., time 3 minutes D0 stage: PC (Pulp concentration) 10%, temperature 60 ° C., time 30 minutes Eop stage: PC (pulp concentration) 10%, temperature 60 ° C., time 120 minutes D1 stage: PC (pulp concentration) 10%, temperature 70 ° C., time 180 minutes ・ Washing conditions at each stage: 90% washing rate (diluted with hollow fiber filtered water to a pulp concentration of 2.5% after bleaching and then dehydrated to a pulp concentration of 20%)
実施例１（ＰｘＺＤ０処理）
絶乾（ＢＤ）質量として５０ｇのアルカリ酸素漂白後の未晒パルプをポリエチレン袋にサンプリングした。パルプ濃度１０％で漂白するために必要な中空糸濾過水を添加後、恒温槽に４５分間浸漬し６０℃にした。このパルプにモノ過流酸処理後のｐＨが３となる量の水酸化ナトリウム、１８．２質量％モノ過硫酸水溶液１．４ｇ（絶乾パルプ当たり０．５質量％）の順に添加・混合した後１０分反応させた。オゾン処理前のモノ過硫酸の消費率は４３％であった。モノ過硫酸処理後直ちにオゾン０．３質量％を添加・混合した後３分間反応させた。オゾン処理後のパルプにすぐさま二酸化塩素０．２質量％を添加・混合した後１０分反応させた。処理後のｐＨは２．５であった。漂白後所定の洗浄条件で洗浄した後、パルプをＢＤとして１６ｇサンプリングし純水で２Ｌに希釈後、亜硫酸水でｐＨ５．５に調整し、ブフナーロート上に２枚のパルプシートを作成した。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 1 (PxZD0 treatment)
As an absolute dry (BD) mass, 50 g of unbleached pulp after alkaline oxygen bleaching was sampled into a polyethylene bag. After adding hollow fiber filtered water necessary for bleaching at a pulp concentration of 10%, it was immersed in a thermostatic bath for 45 minutes to 60 ° C. This pulp was added and mixed in the order of sodium hydroxide in an amount such that the pH after monopersulfuric acid treatment was 3, and 1.4 g of an aqueous solution of 18.2% by mass monopersulfuric acid (0.5% by mass per absolutely dry pulp). The reaction was allowed to proceed for 10 minutes. The consumption rate of monopersulfuric acid before ozone treatment was 43%. Immediately after the monopersulfuric acid treatment, 0.3% by mass of ozone was added and mixed, and then reacted for 3 minutes. The ozone-treated pulp was immediately added and mixed with 0.2% by mass of chlorine dioxide and allowed to react for 10 minutes. The pH after the treatment was 2.5. After bleaching and washing under predetermined washing conditions, 16 g of pulp was sampled as BD, diluted to 2 L with pure water, adjusted to pH 5.5 with sulfite, and two pulp sheets were prepared on the Buchner funnel. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例２（ＰｘＺＤ０処理）
モノ過硫酸量の処理時間を３０分にした以外、実施例１と同様に行った。オゾン処理前のモノ過硫酸の消費率は５８％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 2 (PxZD0 treatment)
The same procedure as in Example 1 was performed except that the treatment time for the amount of monopersulfuric acid was 30 minutes. The consumption rate of monopersulfuric acid before the ozone treatment was 58%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例３（Ｐｘ−ＺＤ０処理）
モノ過硫酸処理後に所定の洗浄条件で洗浄を行った後にオゾン、二酸化塩素処理を行った以外、実施例１と同様に行った。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 3 (Px-ZD0 treatment)
This was carried out in the same manner as in Example 1 except that after treatment with monopersulfuric acid and washing under predetermined washing conditions, treatment with ozone and chlorine dioxide was carried out. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例４（Ｐｘ−ＺＤ０処理）
モノ過硫酸処理後に所定の洗浄条件で洗浄を行った後にオゾン、二酸化塩素処理を行った以外、実施例２と同様に行った。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 4 (Px-ZD0 treatment)
This was performed in the same manner as in Example 2 except that after the monopersulfuric acid treatment, washing was performed under predetermined washing conditions, followed by ozone and chlorine dioxide treatment. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例５（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を６０分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例１と同様に行った。オゾン処理前のモノ過硫酸の消費率は８０％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 5 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 1 except that the treatment time for monopersulfuric acid was 60 minutes and the treatment was performed under the predetermined washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before ozone treatment was 80%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例６（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を１２０分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例１と同様に行った。オゾン処理前のモノ過硫酸の消費率は９４％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 6 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 1 except that the treatment time for monopersulfuric acid was 120 minutes, and washing was carried out under predetermined washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before ozone treatment was 94%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例７（ＰｘＺＤ０処理）
実施例１で用いた１８．２質量％モノ過硫酸水溶液を０．７ｇ添加し、絶乾パルプ当たりのモノ過硫酸の添加率を０．２５質量％にした以外、実施例１と同様に行った。オゾン処理前のモノ過硫酸の消費率は４５％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 7 (PxZD0 treatment)
Performed in the same manner as in Example 1 except that 0.7 g of the 18.2% by mass monopersulfuric acid aqueous solution used in Example 1 was added, and the addition rate of monopersulfuric acid per absolutely dry pulp was 0.25% by mass. It was. The consumption rate of monopersulfuric acid before the ozone treatment was 45%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例８（ＰｘＺＤ０処理）
モノ過硫酸量の処理時間を３０分にした以外、実施例７と同様に行った。オゾン処理前のモノ過硫酸の消費率は５９％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 8 (PxZD0 treatment)
The same procedure as in Example 7 was performed except that the treatment time for the amount of monopersulfuric acid was 30 minutes. The consumption rate of monopersulfuric acid before the ozone treatment was 59%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例９（Ｐｘ−ＺＤ０処理）
モノ過硫酸処理後に所定条件で洗浄を行った後にオゾン、二酸化塩素処理を行った以外、実施例７と同様に行った。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 9 (Px-ZD0 treatment)
This was carried out in the same manner as in Example 7 except that after treatment with monopersulfuric acid and washing under predetermined conditions, treatment with ozone and chlorine dioxide was conducted. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例１０（Ｐｘ−ＺＤ０処理）
モノ過硫酸処理後に所定条件で洗浄を行った後にオゾン、二酸化塩素処理を行った以外、実施例８と同様に行った。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 10 (Px-ZD0 treatment)
It carried out similarly to Example 8 except having performed ozone and the chlorine dioxide process after wash | cleaning on predetermined conditions after the monopersulfuric acid process. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例１１（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を６０分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例７と同様に行った。オゾン処理前のモノ過硫酸の消費率は７２％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 11 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 7 except that the treatment time for monopersulfuric acid was 60 minutes, and washing was carried out under predetermined washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before ozone treatment was 72%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
実施例１２（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を１２０分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例７と同様に行った。オゾン処理前のモノ過硫酸の消費率は８９％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Example 12 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 7 except that the treatment time for monopersulfuric acid was 120 minutes and washing was carried out under predetermined washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before the ozone treatment was 89%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
比較例１（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を１分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例１と同様に行った。オゾン処理前のモノ過硫酸の消費率は２３％であった。１夜風乾後パルプの、ＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Comparative Example 1 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 1 except that the treatment time for monopersulfuric acid was 1 minute, and washing was performed under predetermined washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before the ozone treatment was 23%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
比較例２（Ｐｘ−ＺＤ０処理）
モノ過硫酸の処理時間を１分にして、モノ過硫酸処理後に所定の洗浄条件で洗浄を行った以外、実施例７と同様に行った。オゾン処理前のモノ過硫酸の消費率は１９％であった。１夜風乾後パルプのＨｅｘＡ量、粘度を測定した。結果を表１に示した。
Comparative Example 2 (Px-ZD0 treatment)
The treatment was carried out in the same manner as in Example 7 except that the treatment time for monopersulfuric acid was 1 minute and washing was carried out under the prescribed washing conditions after the monopersulfuric acid treatment. The consumption rate of monopersulfuric acid before the ozone treatment was 19%. After air drying overnight, the HexA content and viscosity of the pulp were measured. The results are shown in Table 1.
モノ過硫酸（ＭＰＳ）添加率が０．５質量％の実施例１〜６と比較例１、またはＭＰＳ添加率が０．２５質量％の実施例７〜１２と比較例２を比較すると、ＭＰＳ消費率を４０％以上にすることにより、ＺＤ０後のＨｅｘＡ量をより低減できることがわかった。また、ＭＰＳ消費率を４０〜６０％の範囲とした実施例１〜４、または実施例７〜１０では、ＺＤ０後の粘度低下を抑制することもできる。さらに、ＭＰＳ添加率が同一の実施例１、２と実施例３、４を比較すると、ＭＰＳ処理後に洗浄を行わないほうが、ＺＤ０後のＨｅｘＡ量をより低減できることがわかった。同様に、実施例７、８と実施例９、１０を比較すると、モノ過硫酸処理後に洗浄を行わない方が、より多くのヘキセンウロン酸が除去されることがわかった。 Comparing Examples 1 to 6 with a monopersulfuric acid (MPS) addition rate of 0.5% by mass and Comparative Example 1 or Examples 7 to 12 with an MPS addition rate of 0.25% by mass and Comparative Example 2, MPS It was found that the amount of HexA after ZD0 can be further reduced by setting the consumption rate to 40% or more. Further, in Examples 1 to 4 or Examples 7 to 10 in which the MPS consumption rate is in the range of 40 to 60%, a decrease in viscosity after ZD0 can be suppressed. Furthermore, when Examples 1 and 2 and Examples 3 and 4 having the same MPS addition rate were compared, it was found that the amount of HexA after ZD0 could be further reduced without washing after MPS treatment. Similarly, when Examples 7 and 8 were compared with Examples 9 and 10, it was found that more hexeneuronic acid was removed when washing was not performed after monopersulfuric acid treatment.
実施例１３（ＰｘＺＤ０−Ｅｏｐ−Ｄ１）
実施例１の条件でＰｘＺＤ０処理したパルプを所定の洗浄条件で洗浄した後、水酸化ナトリウム０．９質量％、酸素０．１５質量％、過酸化水素 ０．３質量％の順に添加し、Ｅｏｐ処理を行った。Ｅｏｐ処理後、所定の洗浄条件で洗浄したパルプに二酸化塩素０．２質量％、所定量の硫酸を加え、Ｄ１処理を行った。尚、硫酸量は反応終了後のｐＨが５になる量を添加した。漂白後所定の洗浄条件で洗浄した後、実施例１と同様に２枚のパルプシートを作成し、１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Example 13 (PxZD0-Eop-D1)
After the pulp treated with PxZD0 under the conditions of Example 1 was washed under predetermined washing conditions, 0.9 mass% sodium hydroxide, 0.15 mass% oxygen, and 0.3 mass% hydrogen peroxide were added in this order. Eop Processed. After the Eop treatment, 0.2% by mass of chlorine dioxide and a predetermined amount of sulfuric acid were added to the pulp washed under predetermined washing conditions, and D1 treatment was performed. In addition, the amount of sulfuric acid was added so that the pH after completion of the reaction was 5. After bleaching and washing under predetermined washing conditions, two pulp sheets were prepared in the same manner as in Example 1, and after air drying overnight, the whiteness, K value, HexA amount, and PC value of the pulp were measured. The results are shown in Table 2.
実施例１４（Ｐｘ−ＺＤ０−Ｅｏｐ−Ｄ１）
実施例１のＰｘＤ０処理パルプの代わりに、実施例３の洗浄後パルプを使用した以外、実施例１３と同様に行った。１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Example 14 (Px-ZD0-Eop-D1)
It carried out similarly to Example 13 except having used the post-washing pulp of Example 3 instead of the PxD0 treated pulp of Example 1. After drying overnight in air, the whiteness, K value, HexA content, and PC value of the pulp were measured. The results are shown in Table 2.
実施例１５（ＰｘＺＤ０−Ｅｏｐ−Ｄ１）
実施例１のＰｘＺＤ０処理パルプの代わりに、実施例７の洗浄後パルプを使用し、Ｄ１処理時の二酸化塩素の添加率を０．２５質量％とした以外、実施例１３と同様に行った。１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Example 15 (PxZD0-Eop-D1)
Instead of the PxZD0 treated pulp of Example 1, the washed pulp of Example 7 was used, and the same procedure as in Example 13 was carried out except that the addition rate of chlorine dioxide during the D1 treatment was 0.25% by mass. After drying overnight in air, the whiteness, K value, HexA content, and PC value of the pulp were measured. The results are shown in Table 2.
実施例１６（Ｐｘ−ＺＤ０−Ｅｏｐ−Ｄ１）
実施例１のＰｘＺＤ０処理パルプの代わりに、実施例９の洗浄後パルプを使用し、Ｄ１処理時の二酸化塩素の添加率を０．２５質量％とした以外、実施例１３と同様に行った。１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Example 16 (Px-ZD0-Eop-D1)
Instead of the PxZD0-treated pulp of Example 1, the pulp after washing of Example 9 was used, and the same procedure as in Example 13 was performed except that the addition rate of chlorine dioxide at the time of D1 treatment was 0.25% by mass. After drying overnight in air, the whiteness, K value, HexA content, and PC value of the pulp were measured. The results are shown in Table 2.
比較例３（Ｐｘ−ＺＤ０−Ｅｏｐ−Ｄ１）
実施例１のＰｘＺＤ０処理パルプの代わりに、比較例１の洗浄後パルプを使用した以外、実施例１３と同様に行った。１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Comparative Example 3 (Px-ZD0-Eop-D1)
Instead of the PxZD0 treated pulp of Example 1, it was carried out in the same manner as Example 13 except that the washed pulp of Comparative Example 1 was used. After drying overnight in air, the whiteness, K value, HexA content, and PC value of the pulp were measured. The results are shown in Table 2.
比較例４（Ｐｘ−ＺＤ０−Ｅｏｐ−Ｄ１）
実施例１のＰｘＺＤ０処理パルプの代わりに、比較例２の洗浄後パルプを使用し、Ｄ１処理時の二酸化塩素の添加率を０．２５質量％とした以外、実施例１３と同様に行った。１夜風乾後パルプの白色度、Ｋ価、ＨｅｘＡ量、ＰＣ価を測定した。結果を表２に示した。
Comparative Example 4 (Px-ZD0-Eop-D1)
Instead of the PxZD0-treated pulp of Example 1, the pulp after washing of Comparative Example 2 was used, and the same procedure as in Example 13 was performed except that the addition rate of chlorine dioxide at the time of D1 treatment was 0.25% by mass. After drying overnight in air, the whiteness, K value, HexA content, and PC value of the pulp were measured. The results are shown in Table 2.
実施例１３、１４と比較例３、または実施例１５、１６と比較例４を比較すると、ＭＰＳの消費率を４０％以上にすることにより、完成パルプのＫ価、ＨｅｘＡ量を褪色への問題がない範囲まで低減でき、褪色性を改善できることが分かった。また、実施例１３〜１６から、ＭＰＳ処理後に洗浄を行わない方（実施例１３、１５）が、よりＨｅｘＡ量を低減できることが分かった。 When Examples 13 and 14 were compared with Comparative Example 3 or Examples 15 and 16 were compared with Comparative Example 4, the problem was that the K value and HexA content of the finished pulp would be discolored by increasing the MPS consumption rate to 40% or more. It can be reduced to a range where there is no discoloration and the discoloration can be improved. Moreover, from Examples 13-16, it turned out that the direction (Examples 13 and 15) which does not wash | clean after MPS process can reduce the amount of HexA more.
Claims (5)
The method for producing bleached pulp according to claim 1 or 2, wherein the consumption rate of monopersulfuric acid is 40 to 60%.
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| WO2015037424A1 (en) * | 2013-09-12 | 2015-03-19 | 三菱瓦斯化学株式会社 | Method for producing cellulose |
| JP2021021165A (en) * | 2019-07-29 | 2021-02-18 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
| WO2022102206A1 (en) * | 2020-11-16 | 2022-05-19 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
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| JP2007308815A (en) * | 2006-05-17 | 2007-11-29 | Oji Paper Co Ltd | Method for producing bleached pulp |
| JP2008088606A (en) * | 2006-10-03 | 2008-04-17 | Oji Paper Co Ltd | Method for producing bleached pulp |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2007308815A (en) * | 2006-05-17 | 2007-11-29 | Oji Paper Co Ltd | Method for producing bleached pulp |
| JP2008088606A (en) * | 2006-10-03 | 2008-04-17 | Oji Paper Co Ltd | Method for producing bleached pulp |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2015037424A1 (en) * | 2013-09-12 | 2015-03-19 | 三菱瓦斯化学株式会社 | Method for producing cellulose |
| JP2021021165A (en) * | 2019-07-29 | 2021-02-18 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
| CN114174589A (en) * | 2019-07-29 | 2022-03-11 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
| CN114174589B (en) * | 2019-07-29 | 2023-02-17 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
| WO2022102206A1 (en) * | 2020-11-16 | 2022-05-19 | 三菱瓦斯化学株式会社 | Method for producing bleached pulp |
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