JP2007270382A - High brightness chemical pulp and method for producing the same - Google Patents
High brightness chemical pulp and method for producing the same Download PDFInfo
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- JP2007270382A JP2007270382A JP2006097777A JP2006097777A JP2007270382A JP 2007270382 A JP2007270382 A JP 2007270382A JP 2006097777 A JP2006097777 A JP 2006097777A JP 2006097777 A JP2006097777 A JP 2006097777A JP 2007270382 A JP2007270382 A JP 2007270382A
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- 229920001131 Pulp (paper) Polymers 0.000 title claims abstract description 41
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 16
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- 238000004061 bleaching Methods 0.000 claims abstract description 53
- 238000005562 fading Methods 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims description 42
- 238000012360 testing method Methods 0.000 claims description 23
- 238000010306 acid treatment Methods 0.000 claims description 17
- 230000007423 decrease Effects 0.000 claims description 9
- 229910052724 xenon Inorganic materials 0.000 claims description 9
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 claims description 9
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- 230000000052 comparative effect Effects 0.000 description 16
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- 229920000881 Modified starch Polymers 0.000 description 2
- 239000004368 Modified starch Substances 0.000 description 2
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 description 2
- KFSLWBXXFJQRDL-UHFFFAOYSA-N Peracetic acid Chemical compound CC(=O)OO KFSLWBXXFJQRDL-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
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- 239000002351 wastewater Substances 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- JNIQBPHJIAOMQU-FSIIMWSLSA-N (2s,3s,4s,5r)-2,3,4,5-tetrahydroxy-6-oxoheptanoic acid Chemical compound CC(=O)[C@H](O)[C@@H](O)[C@H](O)[C@H](O)C(O)=O JNIQBPHJIAOMQU-FSIIMWSLSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- 241000609240 Ambelania acida Species 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 1
- 241000218631 Coniferophyta Species 0.000 description 1
- YZCKVEUIGOORGS-OUBTZVSYSA-N Deuterium Chemical compound [2H] YZCKVEUIGOORGS-OUBTZVSYSA-N 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 101710121765 Endo-1,4-beta-xylanase Proteins 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- 240000000797 Hibiscus cannabinus Species 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- IOVCWXUNBOPUCH-UHFFFAOYSA-N Nitrous acid Chemical compound ON=O IOVCWXUNBOPUCH-UHFFFAOYSA-N 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 229920002873 Polyethylenimine Polymers 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- KDYFGRWQOYBRFD-UHFFFAOYSA-N Succinic acid Natural products OC(=O)CCC(O)=O KDYFGRWQOYBRFD-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 235000011054 acetic acid Nutrition 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 239000002518 antifoaming agent Substances 0.000 description 1
- 239000010905 bagasse Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 238000005282 brightening Methods 0.000 description 1
- 239000004067 bulking agent Substances 0.000 description 1
- KDYFGRWQOYBRFD-NUQCWPJISA-N butanedioic acid Chemical compound O[14C](=O)CC[14C](O)=O KDYFGRWQOYBRFD-NUQCWPJISA-N 0.000 description 1
- 235000009120 camo Nutrition 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 206010061592 cardiac fibrillation Diseases 0.000 description 1
- 235000005607 chanvre indien Nutrition 0.000 description 1
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- 235000015165 citric acid Nutrition 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000004040 coloring Methods 0.000 description 1
- 150000001924 cycloalkanes Chemical class 0.000 description 1
- 230000017858 demethylation Effects 0.000 description 1
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- 238000013461 design Methods 0.000 description 1
- 229910052805 deuterium Inorganic materials 0.000 description 1
- 230000029087 digestion Effects 0.000 description 1
- VTIIJXUACCWYHX-UHFFFAOYSA-L disodium;carboxylatooxy carbonate Chemical compound [Na+].[Na+].[O-]C(=O)OOC([O-])=O VTIIJXUACCWYHX-UHFFFAOYSA-L 0.000 description 1
- GRWZHXKQBITJKP-UHFFFAOYSA-L dithionite(2-) Chemical compound [O-]S(=O)S([O-])=O GRWZHXKQBITJKP-UHFFFAOYSA-L 0.000 description 1
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- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
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- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
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- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
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Landscapes
- Paper (AREA)
Abstract
Description
本発明は高白色度化学パルプ及びその製造方法に関する。更に詳しくは漂白された化学パルプをさらに過酸化水素の存在下で紫外光及び／または可視光で光照射処理することによって得られる、退色性が大幅に改善された、強度低下の少ない新規な高白色度化学パルプ及びその製造方法に関するものである。 The present invention relates to a high whiteness chemical pulp and a method for producing the same. More specifically, the bleached chemical pulp is further subjected to light irradiation treatment with ultraviolet light and / or visible light in the presence of hydrogen peroxide. The present invention relates to a whiteness chemical pulp and a method for producing the same.
化学パルプを主原料とする紙製品、特にインクジェット記録用紙、熱転写記録用紙などの情報記録用紙や写真用印画紙支持体などにおいては高い白色度が要求される。通常、未漂白クラフトパルプの白色度を向上させるために、塩素、次亜塩素酸塩、二酸化塩素、酸素、過酸化水素、オゾンなどの化学薬品で多段漂白することにより未漂白パルプに残留するリグニンや多糖類由来の着色原因物質を除去している。塩素ガスによる塩素漂白法、さらに有機塩素化合物の生成を低減した点でより環境に優しい二酸化塩素によるＥＣＦ漂白法で得られたパルプのＩＳＯ白色度は通常82〜86％である。白色度が通常以上に高いレベルまで漂白された高白色度パルプは蒸解及び／または漂白条件を強化する、あるいはフェノール性の抽出成分含有量の少ない易蒸解で、漂白性の良好な樹種を利用するなどの方法で製造されるのが一般的である。 High whiteness is required for paper products made mainly of chemical pulp, especially information recording paper such as ink jet recording paper and thermal transfer recording paper, and photographic paper support. Usually, to improve the whiteness of unbleached kraft pulp, lignin remaining in unbleached pulp by multi-stage bleaching with chemicals such as chlorine, hypochlorite, chlorine dioxide, oxygen, hydrogen peroxide, ozone, etc. And the color-causing substances derived from polysaccharides are removed. The ISO whiteness of the pulp obtained by the chlorine bleaching method using chlorine gas and further the environmentally friendly ECF bleaching method using chlorine dioxide in terms of reducing the formation of organic chlorine compounds is usually 82 to 86%. High whiteness pulp that has been bleached to a higher whiteness level enhances cooking and / or bleaching conditions, or is easily digested with a low phenolic extractables content and uses a tree with good bleaching properties It is common to manufacture by the method of these.
高白色度パルプを製造する従来の技術としては、例えば、漂白工程として、少なくとも一段以上の塩素系の漂白段を含むシーケンスによって漂白されたパルプを、キシラナーゼで処理し、更に次亜塩素酸塩段と二酸化塩素段の漂白シーケンスで漂白することを特徴とする高白色度パルプの製造方法が開示されている（特許文献１参照）。また、リグノセルロース物質より得られた漂白パルプを、更に高温・高アルカリハイポ晒段と二酸化塩素晒段の連続したシーケンスからなる工程で漂白する高白色度パルプの製造方法において、該二酸化塩素晒段の工程が、二酸化塩素添加率1〜3重量％（対絶乾パルプ）で、かつ91℃以上100℃未満の高温で実施されることを特徴とする高白色度パルプの製造方法が開示されている（特許文献２参照）。また、漂白シーケンスが酸素漂白−オゾン漂白−アルカリ抽出−過酸化水素漂白−二酸化塩素漂白−過酸化水素漂白−二酸化塩素漂白であり、該オゾン漂白工程で絶乾パルプに対して0.1〜1.0重量％のオゾンを用いて漂白された化学パルプであることを特徴とする写真印画紙用支持体原紙について開示されている（特許文献３参照）。さらに、カッパー価が23以下の未晒クラフトパルプを脱リグニン度40％以上で酸素漂白し、次いでパルプ濃度25％以上でオゾン漂白した後、ＰＮ価を2.8以下とし、過酸化水素漂白と二酸化塩素漂白を含む多段漂白を行うことを特徴とする退色性の優れた感材用高白色度パルプの製造方法が開示されている（特許文献４参照）。しかし、従来の方法で得られた高白色度パルプ中には熱や紫外線のいずれか、あるいは両方で濃色化する極微量の潜在的な着色物質が残存しており、経時で白色度が低下する、いわゆる退色現象を避けるのが困難であった。 As a conventional technique for producing a high whiteness pulp, for example, as a bleaching step, a pulp bleached by a sequence including at least one or more chlorinated bleaching stages is treated with a xylanase, and further a hypochlorite stage. And a method for producing a high-whiteness pulp characterized by bleaching in a bleaching sequence of a chlorine dioxide stage (see Patent Document 1). In the method for producing a high whiteness pulp, the bleached pulp obtained from the lignocellulosic material is further bleached in a process comprising a continuous sequence of a high temperature / high alkali hypo bleaching stage and a chlorine dioxide bleaching stage. Is disclosed. A method for producing a high-whiteness pulp is disclosed, wherein the step is performed at a high temperature of 91 ° C. or more and less than 100 ° C. with a chlorine dioxide addition rate of 1 to 3% by weight (relative to dry pulp) (See Patent Document 2). The bleaching sequence is oxygen bleaching-ozone bleaching-alkali extraction-hydrogen peroxide bleaching-chlorine dioxide bleaching-hydrogen peroxide bleaching-chlorine dioxide bleaching, and 0.1 to 1.0% by weight based on the absolutely dry pulp in the ozone bleaching step. There is disclosed a support base paper for photographic printing paper characterized in that it is a chemical pulp bleached with ozone of the above (see Patent Document 3). In addition, unbleached kraft pulp with a kappa number of 23 or less was oxygen bleached at a delignification degree of 40% or higher, then ozone bleached at a pulp concentration of 25% or higher, and the PN number was reduced to 2.8 or lower, hydrogen peroxide bleaching and chlorine dioxide A method for producing a high-whiteness pulp for a light-sensitive material excellent in fading property, characterized by performing multi-stage bleaching including bleaching (see Patent Document 4). However, in the high whiteness pulp obtained by the conventional method, there is a trace amount of latent coloring substances that darken with heat or ultraviolet light, or both, and the whiteness decreases over time. It was difficult to avoid the so-called fading phenomenon.
また、化学パルプの退色に関与する物質として従来のリグニン以外にヘキセンウロン酸が知られている。ヘキセンウロン酸は、蒸解時にヘミセルロース中のメチルグルクロン酸が脱メチル化することで生成する二重結合を有する化合物である。従って、退色しない高白色度パルプ製造には残留リグニンだけでなく、ヘキセンウロン酸も可能な限り除去する必要がある。ヘキセンウロン酸を除去する方法として、漂白前のパルプを85〜150℃かつｐＨ2〜5で処理することで、パルプ中のヘキセンウロン酸の約50％を除去する技術が開示されている（特許文献５参照）。
本発明の目的は、かかる従来技術の欠点を克服し、環境負荷が少なくかつ退色性のない優れた高白色度パルプ、及びそれを含有した紙を提供することにある。 An object of the present invention is to overcome such drawbacks of the prior art, and to provide an excellent high-whiteness pulp with less environmental burden and no fading, and paper containing the same.
本発明者らは、前記従来技術の難点を解消すべく鋭意検討を重ねた結果、漂白処理を行った化学パルプを、過酸化水素の存在下で波長100〜400ｎｍの紫外光及び／または可視光による光照射処理を行い、前記過酸化水素の添加率を絶乾パルプ重量当たり0.1〜5重量％とすることで、白色度が高く、退色性が低いパルプを非常に効率良く製造できること、更にこうして得られたパルプは元の漂白パルプと比較して強度低下が少ないとともに低密度（嵩高）になるという、驚くべき効果を発見し本発明を完成するに至った。 As a result of intensive investigations to solve the problems of the prior art, the present inventors have determined that chemical pulp that has been subjected to bleaching treatment is subjected to ultraviolet light and / or visible light having a wavelength of 100 to 400 nm in the presence of hydrogen peroxide. By performing the light irradiation treatment by the above, and by making the addition rate of hydrogen peroxide 0.1 to 5% by weight per the absolute dry pulp weight, it is possible to produce a pulp having high whiteness and low fading property very efficiently, and thus The obtained pulp was found to have a surprising effect that the strength was reduced as compared with the original bleached pulp and the density became low (bulky), and the present invention was completed.
また、本発明は上記の方法で製造された、ＩＳＯ白色度が89％以上であって、下記の１）及び２）の退色試験のいずれにおいても白色度の低下率が2.0％以下である高白色度化学パルプである。
１）ＪＩＳ Ｐ ８２２２に従って手抄き紙を作成し、Ｊ．ＴＡＰＰＩ Ｎｏ．２１ 紙及び板紙−退色度試験方法のＢ法（キセノンアークランプ式耐光性試験器による方法）に準じて30℃の環境下で、光量67Ｗ／ｍ２のキセノンランプを1時間照射した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める（光退色試験）。
２）ＪＩＳ Ｐ ８２２２に従って手抄き紙を作成し、105℃の送風循環式乾燥機で12時間処理した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める（熱退色試験）。
In addition, the present invention has a high ISO whiteness of 89% or more produced by the above-described method, and a whiteness reduction rate of 2.0% or less in any of the following 1) and 2) fading tests. Whiteness chemical pulp.
1) A handmade paper is prepared according to JIS P 8222. TAPPI No. 21 Paper and paperboard-After irradiating a xenon lamp with a light intensity of 67 W / m 2 for 1 hour in an environment of 30 ° C. in accordance with Method B (method using a xenon arc lamp type light resistance tester) of the fading test method. The whiteness is measured to determine the rate of decrease from the ISO whiteness before processing (photofading test).
2) Hand-made paper is prepared according to JIS P 8222, treated with an air circulation dryer at 105 ° C for 12 hours, ISO whiteness is measured, and the rate of decrease from ISO whiteness before treatment is obtained (heat Fading test).
本発明の新規な漂白法は従来法と比較して、高白色度でありながら、退色性のない漂白化学パルプを提供することが可能となる。さらに本発明で得られる漂白化学パルプは、強度低下が少なく低密度（嵩高）となる。 The novel bleaching method of the present invention can provide a bleached chemical pulp having high whiteness and no fading as compared with the conventional method. Further, the bleached chemical pulp obtained in the present invention has a low density (bulk) with little decrease in strength.
本発明で用いる化学パルプとしては、針葉樹や広葉樹のような木材を原料とするものが好ましいが、ケナフ、麻、バガス、イネ等の非木本性の植物を原料とするものであってもよく、特に限定しない。本発明に使用される化学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、エネルギー効率を考慮すると、クラフト蒸解法が好適である。さらにクラフト蒸解法としては通常法の他、修正蒸解法として、ＭＣＣ、ＥＭＣＣ、ＩＴＣ、Ｌｏ−ｓｏｌｉｄs法等が知られているが、特に限定することなく本発明に適用できる。木材チップは公知の条件でクラフト蒸解することができるが、例えば、次の条件を挙げることができる。蒸解液の硫化度は7〜75％、好ましくは15〜45％、有効アルカリ添加率は絶乾木材重量当り5〜30重量％、好ましくは10〜25重量％、蒸解温度は140〜170℃である。また、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、また蒸解装置の方式は特に問わない。 The chemical pulp used in the present invention is preferably one made of wood such as conifers or hardwoods, but may be made from non-woody plants such as kenaf, hemp, bagasse, rice, etc. There is no particular limitation. As the cooking method for obtaining the chemical pulp used in the present invention, known cooking methods such as kraft cooking, polysulfide cooking, soda cooking, alkali sulfite cooking, etc. can be used, but considering pulp quality and energy efficiency. Then, the kraft cooking method is suitable. Further, as a kraft cooking method, an MCC, EMCC, ITC, Lo-solids method and the like are known as a modified cooking method in addition to a normal method, but can be applied to the present invention without any particular limitation. Wood chips can be kraft cooked under known conditions, for example, the following conditions. The degree of sulfidization of the cooking liquor is 7 to 75%, preferably 15 to 45%, the effective alkali addition rate is 5 to 30% by weight, preferably 10 to 25% by weight, and the cooking temperature is 140 to 170 ° C. is there. Further, the cooking method may be either a continuous cooking method or a batch cooking method, and the method of the cooking device is not particularly limited.
本発明で使用する化学パルプは、公知の蒸解法により得られた未漂白化学パルプを洗浄、粗選及び精選工程を経て、酸素脱リグニン処理されたものである。酸素脱リグニン処理の条件は公知の方法で行うことができる。広葉樹化学パルプの場合、酸素脱リグニン処理後のカッパー価は5〜15の範囲が良く、好ましくは7〜15、さらに好ましくは8〜12である。この酸素脱リグニン処理は公知の中濃度法あるいは高濃度法で実施される。例えば、中濃度法の一般的な反応条件としては、パルプ固形分濃度10〜18重量％、温度100〜110℃、反応時間60〜120分間、反応器内圧力3〜6ｋｇ／ｃｍ２が挙げられ、水酸化ナトリウム添加率及び酸素添加率は目標とするカッパー価によって調整される。 The chemical pulp used in the present invention is one obtained by subjecting unbleached chemical pulp obtained by a known digestion method to oxygen delignification treatment through washing, rough selection and selection processes. The conditions for the oxygen delignification treatment can be performed by a known method. In the case of hardwood chemical pulp, the kappa number after the oxygen delignification treatment is preferably in the range of 5-15, preferably 7-15, more preferably 8-12. This oxygen delignification treatment is carried out by a known medium concentration method or high concentration method. For example, typical reaction conditions for the medium concentration method include pulp solids concentration of 10 to 18% by weight, temperature of 100 to 110 ° C., reaction time of 60 to 120 minutes, and reactor internal pressure of 3 to 6 kg / cm 2. The sodium hydroxide addition rate and the oxygen addition rate are adjusted according to the target kappa number.
本発明の高白色度化学パルプの製造において、酸素脱リグニン処理後のパルプを引き続き酸処理を行ったものを使用することが好ましい。パルプの酸処理に使用する酸の種類は、無機酸でも有機酸でも良い。無機酸としては、硫酸、塩酸、硝酸、亜硫酸、亜硝酸、リン酸、二酸化塩素発生装置の残留酸等の鉱酸を使用できる。好適には硫酸である。有機酸としては、酢酸、乳酸、蓚酸、クエン酸、ギ酸等を使用できる。広葉樹の化学パルプの酸処理時のｐＨは1.5〜6.0の範囲であることが望ましく、好ましくは1.0〜5.0、さらに好ましくは2.0〜5.0、最適には2.5〜3.5である。ｐＨが1.0未満の場合はヘキセンウロン酸と金属イオンの除去は十分であるが、酸が過剰のためパルプ粘度が大幅に低下する。一方、ｐＨが6.0を超えると酸濃度が低く、ヘキセンウロン酸と金属イオンの除去が不充分となる。広葉樹化学パルプの場合、酸処理時のｐＨを2.5〜3.5とすると、酸処理時の温度を低下させることが可能であり、酸処理コストを低減できるという効果が生じてくる。 In the production of the high whiteness chemical pulp of the present invention, it is preferable to use a product obtained by subsequently acid-treating the pulp after the oxygen delignification treatment. The acid used for the acid treatment of the pulp may be an inorganic acid or an organic acid. As the inorganic acid, mineral acids such as sulfuric acid, hydrochloric acid, nitric acid, sulfurous acid, nitrous acid, phosphoric acid, and residual acid of chlorine dioxide generator can be used. Sulfuric acid is preferred. As the organic acid, acetic acid, lactic acid, succinic acid, citric acid, formic acid and the like can be used. The pH of hardwood chemical pulp during acid treatment is desirably in the range of 1.5 to 6.0, preferably 1.0 to 5.0, more preferably 2.0 to 5.0, and most preferably 2.5 to 3.5. When the pH is less than 1.0, the removal of hexeneuronic acid and metal ions is sufficient, but the pulp viscosity is significantly reduced due to the excess of acid. On the other hand, when the pH exceeds 6.0, the acid concentration is low, and the removal of hexeneuronic acid and metal ions becomes insufficient. In the case of hardwood chemical pulp, if the pH during acid treatment is 2.5 to 3.5, the temperature during acid treatment can be lowered, and the effect of reducing the acid treatment cost is produced.
酸処理は大気圧下、加圧下のいずれでも実施可能である。例えば、大気圧下の酸処理時の反応温度は80℃以上100℃未満の範囲である。好ましくは80〜95℃、さらに好ましくは80〜90℃である。温度が30℃以上80℃未満では金属除去の面では効果があるが、ヘキセンウロン酸の除去効果がない。 The acid treatment can be performed under atmospheric pressure or under pressure. For example, the reaction temperature during acid treatment under atmospheric pressure is in the range of 80 ° C. or more and less than 100 ° C. Preferably it is 80-95 degreeC, More preferably, it is 80-90 degreeC. If the temperature is 30 ° C. or higher and lower than 80 ° C., the metal removal is effective, but the hexeneuronic acid is not effective.
また、酸性条件下で行われるオゾン漂白も、本発明の対象とする酸処理の一形態であり、通常のオゾン漂白の条件が適用できる。本発明で適用されるオゾン漂白の条件は、オゾン濃度1〜20重量％のオゾンガスを用いて、ｐＨ1〜7、パルプ濃度0.1〜50重量％、温度は25〜95℃が好適である。また、処理時の圧力については負圧の状態から加圧された状態まで特に限定されない。 In addition, ozone bleaching performed under acidic conditions is one form of acid treatment targeted by the present invention, and normal ozone bleaching conditions can be applied. The ozone bleaching conditions used in the present invention are preferably ozone gas having an ozone concentration of 1 to 20% by weight, pH of 1 to 7, pulp concentration of 0.1 to 50% by weight, and temperature of 25 to 95 ° C. Further, the pressure during the treatment is not particularly limited from a negative pressure state to a pressurized state.
なお、酸処理に際しては、エチレンジアミン四酢酸（ＥＤＴＡ）、ジエチレントリアミン五酢酸（ＤＴＰＡ）等のキレート剤を併用することにより、光照射処理における更に大きな漂白反応促進効果が得られる。 In the acid treatment, a greater bleaching reaction promoting effect in the light irradiation treatment can be obtained by using a chelating agent such as ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) together.
酸処理の結果、その後の紫外光及び／または可視光の光照射処理において漂白効果が促進される理由は明白ではないが、パルプ中の残留リグニンと金属イオン、特に鉄イオンとが金属錯体を形成し、これが光照射処理によって着色化する。従って、酸処理によって金属イオンを除去することによって光照射処理による漂白効果が向上すると推察される。 The reason why the bleaching effect is promoted in the subsequent UV and / or visible light irradiation treatment as a result of acid treatment is not clear, but residual lignin in the pulp and metal ions, especially iron ions, form metal complexes. However, this is colored by the light irradiation treatment. Therefore, it is presumed that the bleaching effect by the light irradiation treatment is improved by removing the metal ions by the acid treatment.
本発明において、酸処理、漂白処理、及び光照射処理の後に、処理パルプの脱水及び／または洗浄を行うが、これらはパルプ製造において公知の脱水機及び／または洗浄機を用いることができる。また、洗浄には新水のほか、酸処理以降の漂白工程で発生する漂白排水や抄紙工程から発生する抄紙排水等を使用することができる。 In the present invention, after the acid treatment, the bleaching treatment, and the light irradiation treatment, the treated pulp is dehydrated and / or washed, and a known dehydrator and / or washing machine can be used for pulp production. In addition to fresh water, bleaching wastewater generated in the bleaching process after the acid treatment, papermaking wastewater generated from the papermaking process, and the like can be used for washing.
酸処理後、パルプは引き続き多段漂白工程で漂白される。使用される薬品としては、原子状塩素（Ｃ）、苛性ソーダ（Ｅ）、次亜塩素酸塩（Ｈ）、二酸化塩素（Ｄ）、酸素（Ｏ）、過酸化水素（Ｐ）、オゾン（Ｚ）、硫酸（Ａ）、有機過酸等の公知の漂白剤と漂白助剤からなる薬品を挙げることができ、これらの中から適宜選択されて漂白薬品として用いられる。漂白シーケンスとしては、特に限定はないが、例えば、Ｃ／Ｄ−Ｅ／Ｏ−Ｈ−Ｄのように原子状塩素と塩素系漂白薬品を含むシーケンス、Ｄ−Ｅ−Ｄ、Ｚ−Ｅ／Ｏ−Ｄのような原子状塩素を含まないＥＣＦ漂白シーケンス、Ｚ−Ｅ−Ｐ、Ａ−Ｚ−Ｅ／Ｏ−Ｐのように塩素系薬品を全く使用しないＴＣＦ漂白シーケンスを用いることができる。 After acid treatment, the pulp is subsequently bleached in a multistage bleaching process. Chemicals used include atomic chlorine (C), caustic soda (E), hypochlorite (H), chlorine dioxide (D), oxygen (O), hydrogen peroxide (P), and ozone (Z). Chemicals comprising known bleaching agents such as sulfuric acid (A) and organic peracids and bleaching assistants can be listed. These are appropriately selected from these and used as bleaching chemicals. The bleaching sequence is not particularly limited. For example, a sequence containing atomic chlorine and a chlorine bleaching chemical such as C / DE / O-HD, DED, ZE / O An ECF bleaching sequence that does not contain atomic chlorine such as -D, and a TCF bleaching sequence that does not use any chlorinated chemicals such as ZEPP or AZE / OP can be used.
本発明の高白色度化学パルプを製造する方法としては、上述した方法で得られた漂白化学パルプをさらに過酸化水素の存在下で光処理にすることが好ましい。また、光処理前の漂白化学パルプは、ＩＳＯ白色度80％以上、好ましくは86％以上となるように漂白されていることが好ましい。例えば、光処理前後にＰ段を導入すれば非常に白色度の高いパルプを容易に得ることができる。 As a method for producing the high whiteness chemical pulp of the present invention, it is preferable that the bleached chemical pulp obtained by the above-described method is further subjected to a light treatment in the presence of hydrogen peroxide. The bleached chemical pulp before phototreatment is preferably bleached so that the ISO whiteness is 80% or more, preferably 86% or more. For example, if the P stage is introduced before and after the light treatment, a pulp having a very high whiteness can be easily obtained.
過酸化水素存在下における紫外光及び／または可視光による光照射処理はアルカリ性条件下で行うことが好ましい。アルカリ性条件としては、ｐＨ10〜13の範囲が好ましい。なお、このｐＨ調整のために使用するアルカリとしては、通常のアルカリ性薬剤が使用可能であるが、アルカリとして水酸化ナトリウムが好適である。また、ｐＨ調整のために使用する酸としては、通常の酸性薬剤が使用可能であるが、硫酸が好適である。 The light irradiation treatment with ultraviolet light and / or visible light in the presence of hydrogen peroxide is preferably performed under alkaline conditions. As alkaline conditions, the range of pH 10-13 is preferable. In addition, as an alkali used for this pH adjustment, although a normal alkaline chemical | medical agent can be used, sodium hydroxide is suitable as an alkali. Moreover, as an acid used for pH adjustment, although a normal acidic chemical | medical agent can be used, a sulfuric acid is suitable.
光照射処理時におけるパルプ濃度は0.1〜12重量％が好ましい。0.1重量％未満では漂白反応効率は高くなるものの、エネルギー効率が低下するため好ましくない。12重量％を超える場合には、漂白装置内でのパルプスラリーの流動性が悪くなり、漂白反応効率が低下するため好ましくない。 The pulp concentration during the light irradiation treatment is preferably 0.1 to 12% by weight. If it is less than 0.1% by weight, the efficiency of the bleaching reaction is increased, but the energy efficiency is lowered, which is not preferable. When it exceeds 12% by weight, the fluidity of the pulp slurry in the bleaching apparatus is deteriorated, and the bleaching reaction efficiency is lowered.
過酸化水素の添加率は対絶乾パルプ重量当たり0.1〜5重量％が好ましく、1〜4重量％がさらに好ましい。添加率が0.1重量％未満では過酸化水素による漂白効果が発揮されず、漂白効率が低下するため好ましくない。一方、5重量％を超える場合には漂白効率の向上は頭打ちとなるので漂白コストが上昇し、また、パルプ強度が低下するため好ましくない。 The addition rate of hydrogen peroxide is preferably from 0.1 to 5% by weight, more preferably from 1 to 4% by weight, based on the weight of the dry pulp. If the addition rate is less than 0.1% by weight, the bleaching effect by hydrogen peroxide is not exhibited and the bleaching efficiency is lowered, which is not preferable. On the other hand, when the amount exceeds 5% by weight, the improvement of the bleaching efficiency reaches its peak, so that the bleaching cost increases and the pulp strength decreases, which is not preferable.
光照射処理時の温度は40〜95℃が好ましい。40℃未満では過酸化水素の反応効率が低く、95℃を超える場合には、パルプ品質の悪化の可能性が生じる、あるいは反応装置内圧力が大気圧を超える可能性も生じるため、耐圧性を考慮した装置設計が必要となる点で、いずれも好ましくない。 The temperature during the light irradiation treatment is preferably 40 to 95 ° C. If the temperature is lower than 40 ° C, the reaction efficiency of hydrogen peroxide is low, and if it exceeds 95 ° C, the pulp quality may deteriorate or the pressure inside the reactor may exceed atmospheric pressure. Neither is preferred in that a device design that takes into account is required.
光照射処理の時間は、原料パルプに含まれる潜在的着色物質の構造やその濃度を考慮することにより適宜定められる。 The time of the light irradiation treatment is appropriately determined by considering the structure of the latent colored substance contained in the raw material pulp and its concentration.
本発明の光照射処理は、波長100〜400ｎｍの紫外光及び／または可視光によるが、当該範囲の波長を有する紫外光単独、可視光単独又はこれらの併用によることができる。本発明の光照射処理において使用する紫外光及び／または可視光としては、特別な制約はないが、波長が100〜400ｎｍ、好ましくは180〜360ｎｍ程度の紫外光を用いることが望ましい。波長が100ｎｍ未満の紫外光では、セルロースの光分解が過剰に促進されるためパルプ強度及び白色度が著しく低下するので好ましくない。また、波長が400ｎｍを超える可視光では、着色物質の光励起が不充分であるため光漂白性が大幅に低下するので好ましくない。 The light irradiation treatment of the present invention is based on ultraviolet light and / or visible light having a wavelength of 100 to 400 nm, but can be performed by ultraviolet light having a wavelength in the above range, visible light alone or a combination thereof. The ultraviolet light and / or visible light used in the light irradiation treatment of the present invention is not particularly limited, but it is desirable to use ultraviolet light having a wavelength of about 100 to 400 nm, preferably about 180 to 360 nm. Ultraviolet light having a wavelength of less than 100 nm is not preferable because photodegradation of cellulose is excessively promoted and pulp strength and whiteness are significantly reduced. Further, visible light having a wavelength exceeding 400 nm is not preferable because the photobleachability is greatly lowered because the colored material is not sufficiently photoexcited.
照射する光源としては、100〜400ｎｍの波長領域の光を持つものが使用でき、具体的には、キセノンショートアークランプ、超高圧水銀ランプ、高圧水銀ランプ、低圧水銀ランプ、重水素ランプ、メタルハライドランプ等［木下忍「ＵＶ照射装置」、接着（２００２年、４６巻７号）ｐ２０〜２７、あるいは杉森彰「光化学 第８章光化学の実験方法Ｉ」、（裳華房、１９９８年発行）ｐ１２６〜１３６、参照］が一例として挙げられ、これらの１種あるいは２種以上を任意に組み合わせて使用することができる。 As a light source for irradiation, a light source having a wavelength range of 100 to 400 nm can be used. Specifically, a xenon short arc lamp, an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deuterium lamp, a metal halide lamp. Etc. [Kinoshita Shinobu "UV Irradiation Device", Adhesion (2002, 46, 7) p20-27, or Sugimori Akira "Photochemistry Chapter 8, Experimental Method I of Photochemistry", (Suikabo, 1998) p126- 136, see] is an example, and one or more of these may be used in any combination.
また、照射反応装置においてパルプが受ける照射の程度は、照射反応装置内でのパルプの滞留時間を調節することや、照射光源のエネルギー量を調節すること等により、任意に設定できる。 Further, the degree of irradiation received by the pulp in the irradiation reactor can be arbitrarily set by adjusting the residence time of the pulp in the irradiation reactor, adjusting the energy amount of the irradiation light source, or the like.
また、135〜242ｎｍの波長領域の光を照射する場合、光源周辺部に連続的に空気および／または酸素を供給することにより、オゾンが生成する。従って、系外からオゾンを供給すること無しに、漂白反応の助剤としてオゾンを利用することもできる。 Moreover, when irradiating light with a wavelength region of 135 to 242 nm, ozone is generated by continuously supplying air and / or oxygen to the periphery of the light source. Accordingly, ozone can be used as an auxiliary for the bleaching reaction without supplying ozone from outside the system.
本発明では光漂白促進剤として、過酸化水素の他にも、公知の還元剤、酸化剤及び水素供与性有機化合物が全て使用できる。このような還元剤としては、例えば、ハイドロサルファイト、水素化ホウ素化合物等を、酸化剤としては、過炭酸ナトリウム、過酢酸等を、水素供与性有機化合物としては、エタノールに代表される一級アルコール等を挙げることができる。また、本発明における添加剤は溶媒を使用せず、単独で用いても良いが、紫外光・可視光を透過する溶媒に分散若しくは溶解させて使用することが望ましい。また、異種添加剤を混合して使用することもできる。このような溶媒としては、水、アルコール類、鎖状または環状のアルカン類、エーテル類等の単独溶媒あるいはこれらの混合溶媒が挙げられるが、水が好ましく使用される。添加剤の使用量は、溶媒に対する添加剤の飽和濃度以下であれば特に制限はないが、好ましくは溶媒に対して0.01〜40重量％、より好ましくは0.1〜20重量％とするのが適当である。 In the present invention, any known reducing agent, oxidizing agent, and hydrogen-donating organic compound can be used in addition to hydrogen peroxide as the photobleaching accelerator. Examples of such reducing agents include hydrosulfite and borohydride compounds, etc., oxidizing agents such as sodium percarbonate and peracetic acid, and hydrogen-donating organic compounds such as primary alcohols represented by ethanol. Etc. Moreover, the additive in the present invention may be used alone without using a solvent, but it is desirable to use it after being dispersed or dissolved in a solvent that transmits ultraviolet light and visible light. Also, different additives can be mixed and used. Examples of such solvents include water, alcohols, chain or cyclic alkanes, single solvents such as ethers, and mixed solvents thereof, and water is preferably used. The amount of the additive used is not particularly limited as long as it is below the saturation concentration of the additive with respect to the solvent, but is preferably 0.01 to 40% by weight, more preferably 0.1 to 20% by weight with respect to the solvent. is there.
また、本発明は、ＩＳＯ白色度が89％以上であって、下記の１）及び２）の退色試験のいずれにおいても白色度の低下率が2.0％以下である高白色度化学パルプである。この高白色度化学パルプは、前述の方法で製造されたものである。
１）ＪＩＳ Ｐ ８２２２に従って手抄き紙を作成し、Ｊ．ＴＡＰＰＩ Ｎｏ．２１ 紙及び板紙−退色度試験方法のＢ法（キセノンアークランプ式耐光性試験器による方法）に準じて30℃の環境下で、光量67Ｗ／ｍ２のキセノンランプを1時間照射した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める（光退色試験）。
２）ＪＩＳ Ｐ ８２２２に従って手抄き紙を作成し、105℃の送風循環式乾燥機で12時間処理した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める（熱退色試験）。
Further, the present invention is a high whiteness chemical pulp having an ISO whiteness of 89% or more and a whiteness reduction rate of 2.0% or less in any of the following fading tests 1) and 2). This high whiteness chemical pulp is produced by the method described above.
1) A handmade paper is prepared according to JIS P 8222. TAPPI No. 21 Paper and paperboard-After irradiating a xenon lamp with a light intensity of 67 W / m 2 for 1 hour in an environment of 30 ° C. in accordance with Method B (method using a xenon arc lamp type light resistance tester) of the fading test method. The whiteness is measured to determine the rate of decrease from the ISO whiteness before processing (photofading test).
2) Hand-made paper is prepared according to JIS P 8222, treated with an air circulation dryer at 105 ° C for 12 hours, ISO whiteness is measured, and the rate of decrease from ISO whiteness before treatment is obtained (heat Fading test).
本発明の高白色度化学パルプを含有する紙の用途としては、書籍用紙の他、オフセット印刷用紙、凸版印刷用紙、グラビア印刷用紙、新聞印刷用紙、電子写真用紙、あるいは塗工紙、インクジェット記録用紙、感熱記録紙、感圧記録紙等の原紙として使用することができる。 Examples of the use of the paper containing the high whiteness chemical pulp of the present invention include book paper, offset printing paper, letterpress printing paper, gravure printing paper, newspaper printing paper, electrophotographic paper, coated paper, and ink jet recording paper. It can be used as a base paper for heat-sensitive recording paper, pressure-sensitive recording paper and the like.
本発明の高白色度化学パルプを含有する紙は、本発明の高白色度化学パルプ以外に原料パルプとして化学パルプ、機械パルプ、脱墨パルプを単独または任意の割合で混合して使用してもよい。抄紙時のｐＨは酸性、中性、アルカリ性のいずれでもよい。 The paper containing the high whiteness chemical pulp of the present invention may be used as a raw material pulp, in addition to the high whiteness chemical pulp of the present invention, with chemical pulp, mechanical pulp, and deinked pulp alone or mixed in any proportion. Good. The pH during papermaking may be acidic, neutral, or alkaline.
本発明の高白色度パルプを含有する紙には、紙力増強剤を含有させることができる。紙力増強剤としては、デンプン、加工デンプン、ポリアクリルアミド、ポリビニルアルコール、ポリアミド・ポリアミン系樹脂、尿素・ホルマリン系樹脂、メラミン・ホルマリン系樹脂、ポリエチレンイミンなどが例示される。紙力増強剤の含有量としては、パルプ絶乾重量当り0.1重量％以上2重量％以下が好ましい。 The paper containing the high whiteness pulp of the present invention can contain a paper strength enhancer. Examples of the paper strength enhancer include starch, modified starch, polyacrylamide, polyvinyl alcohol, polyamide / polyamine resin, urea / formalin resin, melamine / formalin resin, and polyethyleneimine. The content of the paper strength enhancer is preferably 0.1% by weight or more and 2% by weight or less based on the dry pulp weight.
また、本発明の高白色度パルプを含有する紙は填料を含有してもよい。填料としては、ホワイトカーボン、タルク、カオリン、クレー、重質炭酸カルシウム、軽質炭酸カルシウム、酸化チタン、合成樹脂填料等の公知の填料を使用することができる。 The paper containing the high whiteness pulp of the present invention may contain a filler. As the filler, known fillers such as white carbon, talc, kaolin, clay, heavy calcium carbonate, light calcium carbonate, titanium oxide, and synthetic resin filler can be used.
さらに、本発明の高白色度パルプを含有する紙は、必要に応じて硫酸バンド、サイズ剤、歩留まり向上剤、濾水性向上剤、着色剤、染料、消泡剤、嵩高剤、蛍光増白剤等を含有してもよい。 Further, the paper containing the high whiteness pulp of the present invention may be a sulfuric acid band, a sizing agent, a yield improver, a drainage improver, a colorant, a dye, an antifoaming agent, a bulking agent, and a fluorescent brightening agent. Etc. may be contained.
本発明の高白色度パルプを含有する紙は、全く塗工処理をしていないか、あるいは顔料を含まない表面処理剤を塗工してもよい。非塗工用紙の場合、表面強度やサイズ性向上の目的で、水溶性高分子を主成分とする表面処理剤を塗工することが望ましい。水溶性高分子としては、デンプン、加工デンプン、ポリアクリルアミド、ポリビニルアルコール等の表面処理剤として通常使用されるものを単独、あるいはこれらの混合物を使用することができる。また、表面処理剤の中には、水溶性高分子の他に耐水性、表面強度向上を目的とした紙力増強剤やサイズ性付与を目的とした外添サイズ剤を添加することができる。表面処理剤の塗布量としては、表面処理剤は、２ロールサイズプレスコーター、ゲートロールコーター、ブレードメタリングコーター、ロッドメタリングコーター等の塗工機によって塗布することができる。表面処理剤の塗布量としては、片面当り0.1ｇ／ｍ２以上3ｇ／ｍ２以下が好ましい。
［作用］
本発明で得られた高白色度化学パルプの退色性が極めて小さい理由は明らかではないが、次の２点が推察される。１）254ｎｍの非常に強い紫外光でパルプ中に残存する退色に関与する着色原因物質が分解、除去されることで、熱や比較的弱い紫外光による退色が極めて少なくなる。２）適量の過酸化水素の存在下で紫外光が照射されることにより、非常に酸化力の強いラジカル種、例えばヒドロキシラジカルが生成し、これがパルプ中に残存する退色に関与する着色原因物質を分解・除去することによって、熱や比較的弱い紫外光による退色が極めて少なくなる。
The paper containing the high whiteness pulp of the present invention may not be coated at all or may be coated with a surface treatment agent containing no pigment. In the case of non-coated paper, it is desirable to apply a surface treatment agent mainly composed of a water-soluble polymer for the purpose of improving the surface strength and size. As the water-soluble polymer, those usually used as surface treating agents such as starch, modified starch, polyacrylamide, polyvinyl alcohol and the like can be used alone or as a mixture thereof. In addition to the water-soluble polymer, a paper strength enhancer for the purpose of improving water resistance and surface strength and an externally added sizing agent for the purpose of imparting sizing can be added to the surface treatment agent. As the coating amount of the surface treatment agent, the surface treatment agent can be applied by a coating machine such as a 2-roll size press coater, a gate roll coater, a blade metalling coater, or a rod metalling coater. The coating amount of the surface treatment agent, per side 0.1 g / m 2 or more 3 g / m 2 or less.
[Action]
The reason why the fading property of the high whiteness chemical pulp obtained in the present invention is extremely small is not clear, but the following two points are presumed. 1) The color-causing substance involved in fading remaining in the pulp is decomposed and removed by very strong ultraviolet light of 254 nm, so that fading due to heat or relatively weak ultraviolet light is extremely reduced. 2) Irradiation with ultraviolet light in the presence of an appropriate amount of hydrogen peroxide generates radical species with a very strong oxidizing power, such as hydroxy radicals, which are responsible for the color-causing substances involved in fading remaining in the pulp. By decomposing and removing, fading due to heat and relatively weak ultraviolet light is extremely reduced.
また、本発明で得られた高白色度化学パルプの強度低下が少なくより低密度である理由も明らかではないが、適量の過酸化水素の存在下で紫外光が照射されることにより酸化力の強いラジカル種が生じ、パルプ繊維表面のセルロース水酸基がカルボキシル基へ酸化されると推察される。カルボキシル基は水酸基に比べて親水性が高く、水素結合力に優れる。これにより、所望の濾水度を得るのに要する叩解の機械力が低減して所望の濾水度における密度が小さくなる一方、叩解による機械力を低減させることによりパルプ繊維のフィブリル化を進めなくても比較的強度が大きくなると推察される。 In addition, although the reason why the strength of the high whiteness chemical pulp obtained in the present invention is low and the density is lower is not clear, it is not clear that the oxidizing power is reduced by irradiation with ultraviolet light in the presence of an appropriate amount of hydrogen peroxide. It is inferred that strong radical species are generated and the cellulose hydroxyl group on the pulp fiber surface is oxidized to a carboxyl group. The carboxyl group has higher hydrophilicity than the hydroxyl group and is excellent in hydrogen bonding force. This reduces the mechanical force of beating required to obtain the desired freeness and reduces the density at the desired freeness, while reducing the mechanical force due to beating, and does not promote fibrillation of pulp fibers. However, it is assumed that the strength becomes relatively large.
以下に実施例に基づき、本発明をさらに詳細に説明するが、本発明はこれらに限定されるものではない。実施例、比較例で得られたパルプについて下記の項目について、評価を行った。
・パルプの白色度測定：パルプを離解した後、ＪＩＳ Ｐ ８２０９に従って坪量60ｇ／ｍ２の手抄きシートを作製し、ＪＩＳ Ｐ ８１４８に準じてパルプのＩＳＯ白色度を測定した。
・熱退色試験：上記のパルプシートを、105℃の送風循環式恒温槽で12時間退色させた後、白色度を測定した。
・光退色試験：キセノンランプウェザーメーターを用いて行った。キセノンランプから発生する紫外線を1時間サンプルに照射した後、ＩＳＯ白色度（ＪＩＳ Ｐ ８１４８）を測定した。退色試験は温度30℃、光量67Ｗ／ｍ２で実施した。なお、表１中Δ白色度、白色度低下率は下記のように定義される。（熱退色、光退色とも）
Δ白色度＝退色試験前のＩＳＯ白色度−退色試験後のＩＳＯ白色度
白色度低下率＝Δ白色度／退色試験前のＩＳＯ白色度
・裂断長の測定：濃度10％のパルプスラリーをＰＦＩミルでカナダ標準濾水度（ＣＳＦ）400ｍＬになるように叩解し、上記と同様な方法によって坪量60ｇ／ｍ２のシートを作製し、ＪＩＳ Ｐ ８１１３に従って裂断長を測定した。
・密度の測定：裂断長の測定に用いたシートを、ＪＩＳ Ｐ ８１１８の方法に従って密度を測定した。
・紫外光漂白実験装置：実施例で用いた紫外光漂白実験装置を図１に示した。155ｍｍ（φ）×600ｍｍ（Ｈ）のステンレス製円筒形の紫外光照射反応槽の中央部に無電極低圧水銀ランプ（500Ｗ、116ｍｍ（φ）×576ｍｍ（Ｈ）、ハリソン東芝ライティング社製ＧＬ1500ＭＳ/31）を固定し、（有効容積5.2L）パルプスラリーは反応漕内をアップフローで移動する。光漂白後のパルプスラリーはストックタンク（容量30Ｌ）を経由した後、ポンプで反応槽に繰り返し送液循環できるようにした。
［実施例１］
広葉樹の酸素脱リグニン後のクラフトパルプに対して、パルプ濃度10重量％、ｐＨ3.0（硫酸使用）、温度95℃、処理時間180分で酸処理を行い、酸処理終了後パルプを水洗した。これをさらに漂白して、広葉樹漂白パルプ（ＩＳＯ白色度86.6％）を得た。これを200ｇ（絶乾重量）採り、パルプ濃度を1重量％とした後、水酸化ナトリウムを用いてｐＨ11.5に調整した。このスラリーを図１の紫外光漂白実験装置を用いて、過酸化水素を2.0ｇ（絶乾パルプ重量に対して1重量％）添加し、撹拌しながら、温度60℃、254ｎｍに主波長を持つ低圧水銀ランプを使用して紫外光処理時間30分で紫外光照射処理を行った。処理が終了したパルプは洗浄した後、手抄シートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長及び密度を測定し、結果を表１に示した。
［実施例２］
紫外光処理時間を70分とした以外は、実施例１と同様な条件で紫外光照射処理を行なった。処理が終了したパルプは洗浄した後、シートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長及び密度を測定した。結果を表１に示した。
［実施例３］
過酸化水素の添加量を8.0ｇ（絶乾パルプ重量に対して4重量％）とした以外は、実施例１と同様な条件で紫外光照射処理を行なった。処理が終了したパルプは洗浄した後、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長及び密度を測定した。結果を表１に示した。
［比較例１］
実施例１で使用した広葉樹漂白パルプ（ＩＳＯ白色度86.6％）を用いて、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長および密度を測定した。結果を表１に示した。
［比較例２］
過酸化水素の添加量を0ｇ、紫外光処理時間を160分とした以外は、実施例と同様な条件で紫外光照射処理を行った。処理が終了したパルプは洗浄した後、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長および密度を測定した。結果を表１に示した。
［比較例３］
過酸化水素の添加量を0.1ｇ（絶乾パルプ重量に対して0.05重量％）、紫外光処理時間を100分とした以外は、実施例１と同様な条件で紫外光照射処理を行なった。処理が終了したパルプは洗浄した後、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長及び密度を測定した。結果を表１に示した。
［比較例４］
過酸化水素の添加量を12ｇ（絶乾パルプ重量に対して6重量％）とした以外は、実施例１と同様な条件で紫外光照射処理を行なった。処理が終了したパルプは洗浄した後、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長及び密度を測定した。結果を表１に示した。
［比較例５］
実施例１で使用した広葉樹漂白パルプ（ＩＳＯ白色度85.6％）を100ｇ（絶乾重量）採り、パルプ濃度を10重量％とした後、水酸化ナトリウムを用いてｐＨ11.5に調整した。このスラリーに過酸化水素を1.0ｇ（絶乾パルプ重量に対して1重量％）添加し、温度60℃、処理時間180分で、漂白処理を行った。処理が終了したパルプは洗浄した後、手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長を測定した。結果を表１に示した。
［比較例６］
市販の二酸化塩素ＥＣＦ漂白法により得られた広葉樹漂白パルプ（ＩＳＯ白色度89.7％）を用いて手抄きシートを作成し白色度を測定した。退色試験には前記白色度測定後のシートを用いた。また、叩解処理後のパルプから手抄きシートを作成し、裂断長を測定した。結果を表１に示した。
Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto. The following items were evaluated for the pulps obtained in Examples and Comparative Examples.
-Pulp whiteness measurement: After the pulp was disaggregated, a handsheet having a basis weight of 60 g / m 2 was prepared according to JIS P 8209, and the ISO whiteness of the pulp was measured according to JIS P 8148.
-Thermal fading test: The above-mentioned pulp sheet was faded for 12 hours in an air circulation thermostat at 105 ° C, and the whiteness was measured.
-Photobleaching test: A xenon lamp weather meter was used. After irradiating the sample with ultraviolet rays generated from a xenon lamp for 1 hour, ISO whiteness (JIS P 8148) was measured. The fading test was performed at a temperature of 30 ° C. and a light amount of 67 W / m 2 . In Table 1, Δ whiteness and whiteness reduction rate are defined as follows. (Both thermal fading and light fading)
Δ Whiteness = ISO whiteness before fading test−ISO whiteness after fading test Whiteness reduction rate = ΔWhiteness / ISO whiteness / breaking length measurement before fading test: Pulp slurry with 10% concentration The mill was beaten to a Canadian standard freeness (CSF) of 400 mL, a sheet having a basis weight of 60 g / m 2 was produced by the same method as described above, and the breaking length was measured according to JIS P8113.
Measurement of density: The density of the sheet used for the measurement of tearing length was measured according to the method of JIS P 8118.
Ultraviolet light bleaching experimental apparatus: The ultraviolet light bleaching experimental apparatus used in the examples is shown in FIG. 155mm (φ) × 600mm (H) stainless steel cylindrical ultraviolet irradiation reactor at the center of the electrodeless low-pressure mercury lamp (500W, 116mm (φ) × 576mm (H), GL1500MS / 31 by Harrison Toshiba Lighting ) (Effective volume 5.2L) Pulp slurry moves up-flow in the reaction tank. The pulp slurry after photobleaching was allowed to be repeatedly sent and circulated to the reaction tank with a pump after passing through a stock tank (capacity 30 L).
[Example 1]
The kraft pulp after oxygen delignification of hardwood was subjected to acid treatment at a pulp concentration of 10% by weight, pH 3.0 (using sulfuric acid), temperature of 95 ° C., treatment time of 180 minutes, and after completion of the acid treatment, the pulp was washed with water. This was further bleached to obtain hardwood bleached pulp (ISO whiteness 86.6%). 200 g (absolute dry weight) of this was taken, the pulp concentration was adjusted to 1% by weight, and the pH was adjusted to 11.5 using sodium hydroxide. This slurry was added with 2.0 g of hydrogen peroxide (1% by weight with respect to the weight of the absolutely dry pulp) using the ultraviolet light bleaching experimental apparatus shown in FIG. 1, and had a dominant wavelength at a temperature of 60 ° C. and 254 nm while stirring. Using a low-pressure mercury lamp, ultraviolet light irradiation treatment was performed with an ultraviolet light treatment time of 30 minutes. The treated pulp was washed and then a handsheet was prepared to measure the whiteness. The sheet after the whiteness measurement was used for the fading test. Moreover, a handsheet was prepared from the pulp after the beating treatment, the tear length and density were measured, and the results are shown in Table 1.
[Example 2]
The ultraviolet light irradiation treatment was performed under the same conditions as in Example 1 except that the ultraviolet light treatment time was set to 70 minutes. The treated pulp was washed, then a sheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Moreover, a handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Example 3]
The ultraviolet light irradiation treatment was performed under the same conditions as in Example 1 except that the amount of hydrogen peroxide added was 8.0 g (4% by weight based on the weight of the absolutely dry pulp). After the treatment, the pulp was washed, then a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Moreover, a handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Comparative Example 1]
Using the hardwood bleached pulp (ISO whiteness 86.6%) used in Example 1, a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. A handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Comparative Example 2]
The ultraviolet light irradiation treatment was performed under the same conditions as in the Examples except that the amount of hydrogen peroxide added was 0 g and the ultraviolet light treatment time was 160 minutes. After the treatment, the pulp was washed, then a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. A handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Comparative Example 3]
The ultraviolet light irradiation treatment was performed under the same conditions as in Example 1 except that the amount of hydrogen peroxide added was 0.1 g (0.05% by weight based on the weight of the absolutely dry pulp) and the ultraviolet light treatment time was 100 minutes. After the treatment, the pulp was washed, then a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Moreover, a handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Comparative Example 4]
The ultraviolet light irradiation treatment was performed under the same conditions as in Example 1 except that the amount of hydrogen peroxide added was 12 g (6% by weight based on the weight of the absolutely dry pulp). After the treatment, the pulp was washed, then a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Moreover, a handsheet was prepared from the pulp after the beating treatment, and the breaking length and density were measured. The results are shown in Table 1.
[Comparative Example 5]
100 g (absolutely dry weight) of hardwood bleached pulp (ISO whiteness 85.6%) used in Example 1 was taken, the pulp concentration was adjusted to 10% by weight, and adjusted to pH 11.5 using sodium hydroxide. To this slurry, 1.0 g of hydrogen peroxide (1% by weight with respect to the weight of the absolutely dry pulp) was added, and bleaching was performed at a temperature of 60 ° C. and a processing time of 180 minutes. After the treatment, the pulp was washed, then a handsheet was prepared and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Further, a handsheet was prepared from the pulp after the beating treatment, and the breaking length was measured. The results are shown in Table 1.
[Comparative Example 6]
A handmade sheet was prepared using a hardwood bleached pulp (ISO whiteness 89.7%) obtained by a commercially available chlorine dioxide ECF bleaching method, and the whiteness was measured. The sheet after the whiteness measurement was used for the fading test. Further, a handsheet was prepared from the pulp after the beating treatment, and the breaking length was measured. The results are shown in Table 1.
また、実施例１〜３の高白色度パルプは、処理前の漂白パルプ（比較例１）と比較すると、裂断長がほぼ同水準でありながら密度が低いことが分かる。一方、漂白パルプを絶乾パルプ当たり6重量％の過酸化水素の存在下で紫外光処理することで得られた高白色度パルプ（比較例４）や漂白パルプの過酸化水素漂白で得られた高白色度パルプ（比較例５）、市販の高白色度パルプ（比較例６）は通常の漂白パルプ（比較例２）よりも相対的に裂断長が小さいか、密度が大きいことが分かる。 Moreover, when the high whiteness pulp of Examples 1-3 is compared with the bleached pulp before a process (comparative example 1), it turns out that the density is low, although the tearing length is substantially the same level. On the other hand, bleached pulp was obtained by hydrogen peroxide bleaching of high-whiteness pulp (Comparative Example 4) or bleached pulp obtained by ultraviolet light treatment in the presence of 6% by weight of hydrogen peroxide per absolute dry pulp. It can be seen that the high-whiteness pulp (Comparative Example 5) and the commercially available high-whiteness pulp (Comparative Example 6) have a relatively smaller tear length or a higher density than the ordinary bleached pulp (Comparative Example 2).
Claims (5)
１）ＪＩＳ Ｐ ８２２２に従って作成した手抄き紙を、Ｊ．ＴＡＰＰＩ Ｎｏ．２１ 紙及び板紙−退色度試験方法のＢ法（キセノンアークランプ式耐光性試験器による方法）に準じて30℃の環境下で、光量67Ｗ／ｍ２のキセノンランプを1時間照射した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める。
２）ＪＩＳ Ｐ ８２２２に従って作成した手抄き紙を、105℃の送風循環式乾燥機で12時間処理した後、ＩＳＯ白色度を測定し、処理前のＩＳＯ白色度との低下率を求める。
のいずれにおいても白色度の低下率が2.0％以下である請求項１〜３のいずれかに記載の高白色度化学パルプの製造方法。 ISO whiteness is 89% or more, and the following 1) and 2) fading test:
1) Hand-made paper prepared according to JIS P 8222 TAPPI No. 21 Paper and paperboard-After irradiating a xenon lamp with a light intensity of 67 W / m 2 for 1 hour in an environment of 30 ° C. in accordance with Method B (method using a xenon arc lamp type light resistance tester) of the fading test method. The whiteness is measured, and the rate of decrease from the ISO whiteness before processing is obtained.
2) A handmade paper prepared in accordance with JIS P 8222 is treated with an air circulation dryer at 105 ° C. for 12 hours, and then the ISO whiteness is measured to determine the rate of decrease from the ISO whiteness before treatment.
The method for producing a high whiteness chemical pulp according to any one of claims 1 to 3, wherein the whiteness reduction rate is 2.0% or less.
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| CN102296476A (en) * | 2010-06-25 | 2011-12-28 | 温战军 | Photodynamic chemical transformation pulping technology and pulping machine |
| JP2013198424A (en) * | 2012-03-23 | 2013-10-03 | Nippon Paper Industries Co Ltd | Treatment method of plant-based raw material |
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