JPH024717B2 - - Google Patents
Info
- Publication number
- JPH024717B2 JPH024717B2 JP3600285A JP3600285A JPH024717B2 JP H024717 B2 JPH024717 B2 JP H024717B2 JP 3600285 A JP3600285 A JP 3600285A JP 3600285 A JP3600285 A JP 3600285A JP H024717 B2 JPH024717 B2 JP H024717B2
- Authority
- JP
- Japan
- Prior art keywords
- waste paper
- cooking
- temperature
- dithionite
- sodium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000010893 paper waste Substances 0.000 claims description 54
- 238000000034 method Methods 0.000 claims description 53
- 238000010411 cooking Methods 0.000 claims description 41
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 claims description 22
- 239000003795 chemical substances by application Substances 0.000 claims description 16
- GRWZHXKQBITJKP-UHFFFAOYSA-L dithionite(2-) Chemical compound [O-]S(=O)S([O-])=O GRWZHXKQBITJKP-UHFFFAOYSA-L 0.000 claims description 16
- RYYXDZDBXNUPOG-UHFFFAOYSA-N 4,5,6,7-tetrahydro-1,3-benzothiazole-2,6-diamine;dihydrochloride Chemical compound Cl.Cl.C1C(N)CCC2=C1SC(N)=N2 RYYXDZDBXNUPOG-UHFFFAOYSA-N 0.000 claims description 13
- 239000000126 substance Substances 0.000 claims description 12
- 235000010265 sodium sulphite Nutrition 0.000 claims description 11
- 239000004094 surface-active agent Substances 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 7
- 230000029087 digestion Effects 0.000 claims description 3
- 239000003814 drug Substances 0.000 claims description 3
- 229940079593 drug Drugs 0.000 claims description 3
- 239000000976 ink Substances 0.000 description 16
- 239000002351 wastewater Substances 0.000 description 14
- 239000002761 deinking Substances 0.000 description 13
- 239000000835 fiber Substances 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 10
- 230000008569 process Effects 0.000 description 9
- JVBXVOWTABLYPX-UHFFFAOYSA-L sodium dithionite Chemical group [Na+].[Na+].[O-]S(=O)S([O-])=O JVBXVOWTABLYPX-UHFFFAOYSA-L 0.000 description 9
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 8
- 238000012545 processing Methods 0.000 description 8
- 238000007796 conventional method Methods 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 230000002829 reductive effect Effects 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000003513 alkali Substances 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- 238000004061 bleaching Methods 0.000 description 4
- 238000004042 decolorization Methods 0.000 description 4
- 239000013505 freshwater Substances 0.000 description 4
- -1 polyoxyethylene Polymers 0.000 description 4
- 239000011734 sodium Substances 0.000 description 4
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 3
- 239000002736 nonionic surfactant Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 235000017550 sodium carbonate Nutrition 0.000 description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 description 3
- 238000009423 ventilation Methods 0.000 description 3
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 125000005037 alkyl phenyl group Chemical group 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 210000000988 bone and bone Anatomy 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 230000015271 coagulation Effects 0.000 description 2
- 238000005345 coagulation Methods 0.000 description 2
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 150000004679 hydroxides Chemical class 0.000 description 2
- WQYVRQLZKVEZGA-UHFFFAOYSA-N hypochlorite Chemical compound Cl[O-] WQYVRQLZKVEZGA-UHFFFAOYSA-N 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 238000004062 sedimentation Methods 0.000 description 2
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical class O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- DWAQJAXMDSEUJJ-UHFFFAOYSA-M Sodium bisulfite Chemical compound [Na+].OS([O-])=O DWAQJAXMDSEUJJ-UHFFFAOYSA-M 0.000 description 1
- 239000004280 Sodium formate Substances 0.000 description 1
- 239000005708 Sodium hypochlorite Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 239000003945 anionic surfactant Substances 0.000 description 1
- 229910052788 barium Inorganic materials 0.000 description 1
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- XQIMLPCOVYNASM-UHFFFAOYSA-N borole Chemical compound B1C=CC=C1 XQIMLPCOVYNASM-UHFFFAOYSA-N 0.000 description 1
- 230000009172 bursting Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 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
- 230000001804 emulsifying effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 239000011591 potassium Substances 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000009895 reductive bleaching Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- XWGJFPHUCFXLBL-UHFFFAOYSA-M rongalite Chemical compound [Na+].OCS([O-])=O XWGJFPHUCFXLBL-UHFFFAOYSA-M 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- 239000000344 soap Substances 0.000 description 1
- 229910000033 sodium borohydride Inorganic materials 0.000 description 1
- 239000012279 sodium borohydride Substances 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- HLBBKKJFGFRGMU-UHFFFAOYSA-M sodium formate Chemical compound [Na+].[O-]C=O HLBBKKJFGFRGMU-UHFFFAOYSA-M 0.000 description 1
- 235000019254 sodium formate Nutrition 0.000 description 1
- 235000010267 sodium hydrogen sulphite Nutrition 0.000 description 1
- 229940045872 sodium percarbonate Drugs 0.000 description 1
- 235000019832 sodium triphosphate Nutrition 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 150000003871 sulfonates Chemical class 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/64—Paper recycling
Landscapes
- Paper (AREA)
Description
〔産業上の利用分野〕
本発明は古紙の再生方法に関し、さらに詳しく
は本発明は亜硫酸ソーダを使用することなく、蒸
解法により汚濁の発生量が少なく、したがつて排
水CODが極めて低く、かつ古紙の離解がよく、
古紙繊維の損傷が少ない高白度、高強度の再生パ
ルプを得る古紙の再生方法に関する。
〔従来技術およびその問題点〕
古紙は製紙原料として約40％に達し、原木と共
に重要なパルプ資源となつているが、最近の世界
的な原木事情の逼迫とエネルギーコストの上昇は
古紙再生の重要性を増大している。中でも印刷古
紙の脱インク再生は古紙の高度利用として注目さ
れ、効率的な脱インク技術の開発が強く要望され
ている。
従来行われている印刷古紙の代表的脱インク処
理方法は、(1)高温加圧蒸解法、(2)パルパー法の二
つである。このうち高温加圧蒸解法は古くから行
なわれている方法であり、球形の加圧釜に原料古
紙および、たとえば亜硫酸ソーダ、アルカリ剤、
界面活性剤からなる薬剤を入れ、高温、高圧（約
120℃〜150℃）に於いて釜を回転させながら蒸解
し、続いて離解処理を行つた後、異物除去のため
の徐塵をしたのち洗浄され、更に必要に応じ過酸
化水素、次亜塩素酸ソーダ等の酸化剤により漂白
されて再生パルプとされる。
しかしこの方法の場合高温、高圧処理のため古
紙繊維の損傷が激しく、(1)紙力が低下する。(2)歩
留りが悪い。(3)排水CODが高い。又高温にする
ため、(4)エネルギーコストがかかる。(5)耐圧釜を
必要とするため装置コストがかかる。その他脱イ
ンク終了後高圧蒸気をブローする場合、騒音と悪
臭がひどくしばしば公害問題に発展する等種々の
欠点を有している。
特に排水COD規制に関しては年々厳しくなつ
ており、凝集沈澱処理だけで対処している工場の
場合排水COD対策は最重要テーマになつている。
従つてこれ等の欠点を改良するために蒸解温度を
下げる等の対策を実施するところが多くなつてき
た。しかし薬液としては一般に亜硫酸ソーダ２〜
３％、ソーダ灰0.5〜1.0％から成る薬液が使用さ
れていることから自ずと蒸解温度の低下にも限度
があり、100〜120℃が限度とされている。
蒸解温度をさらに下げた場合、インクの脱色が
不良となり脱墨不能になる。また古紙の離解性が
悪くなり末離解繊維が多量に発生する欠点があ
る。
したがつて亜硫酸ソーダを使用する限り低温蒸
解はできない。
一方、排水CODを低減させる方法として、従
来の亜硫酸ソーダのかわりに過炭酸ソーダを使用
する方法がある。（特開昭59−192792号公報）し
かし、この方法では蒸解温度は90〜180℃と依然
として高温であり、古紙繊維の損傷は避け難く、
離解性も悪い。また排水CODも思つた程低下し
ない。また、亜硫酸ソーダおよびハイドロサルフ
アイトを用いて古紙を蒸解する方法が知られてい
る（特開昭51−36362号公報）。この方法は公報の
記載から明らかに理解される様に、従来の高温加
圧蒸解法をそのまま適用し、薬剤として亜硫酸ソ
ーダとともにハイドロサルフアイトの様な還元漂
白剤を使用する方法であり、蒸解処理は従来の様
に高温、高圧で行うものである。
したがつて古紙繊維の損傷は避けられず、その
上排水汚濁量が多く排水CODが高い。
なお、特公昭51−36362号公報の記載に順じて、
亜硫酸ソーダ、ハイドロサルフアイトを用いて60
℃のごとき低温で蒸解処理した場合、後述の比較
例に示す様にハイドロサルフアイトによる漂白、
脱色の効果は一応認められるが、亜硫酸ソーダに
よる古紙蒸解法における古紙の離解作用および脱
墨作用は温度の影響が非常に大きいことから古紙
の離解性が著しく悪化しリジエクト率（末離解古
紙の量）が増加すると共に製品上の残インク率も
著しく増加する。
〔発明が解決しようとする問題点〕
本発明は、上記の如き従来の高温高圧下で実施
される蒸解法による古紙の脱墨、再生法にみられ
る短所に鑑み、蒸解法の長所を生かし、汚濁発生
量を少なくし排水CODを低下させ、かつ古紙の
離解性が良く、アルカリ性薬品に対して強い抵抗
を示すインクを用いた古紙からのインクの脱色に
すぐれた高白度、高強度の再生パルプを得ること
にある。
蒸解法による場合、汚濁の発生量を少なくし、
かつ高白度、高強度の再生古紙を得るためには、
先ず蒸解温度を下げて古紙繊維の損傷を最小限に
抑えることが必要である。
そこで、本発明者らは従来の加圧蒸解釜を使用
しかつ100℃より低い低温度でアルカリ剤と界面
活性剤を用いて、脱墨と繊維の離解を同時に達成
する方法について鋭意研究を行つた結果、アルカ
リによるインクの鹸化および界面活性剤による乳
化分散によりある程度繊維からインクを離脱分散
させると同時に、繊維を離解出来ることを知つ
た。しかし、アルカリだけでは多色印刷古紙に使
用しているアルカリ系薬品に対し強い抵抗を持つ
インクの除去は不充分であり、残色により着色し
た再生古紙が得られた。そこでこれらのインクの
除去のために多量のアルカリを使用した場合に
は、たとえ低温で蒸解しても古紙繊維の損傷が起
こり、また排水CODの上昇、歩留り低下、繊維
のアルカリ着色による白色度の低下が起こること
が判つた。
〔問題点を解決するための手段〕
そこで、本発明者らは必要最小限のアルカリ剤
量で脱墨、離解を行うと同時に、亜二チオン酸塩
または二酸化チオ尿素の如き強還元剤を使用し、
アルカリ系薬品に対して強い抵抗を持つた着色イ
ンクの還元脱色と古紙繊維の漂白とを同時に行う
ことにより、従来の蒸解法に比べて著しく汚濁の
発生量も少なく、かつ高白度、高強度の再生パル
プを得ることができることを見出し本発明を完成
した。
すなわち、本発明は、亜硫酸ソーダを使用する
ことなく、亜二チオン酸塩または二酸化チオ尿素
のいずれか一種と、アルカリ剤とからなる薬剤を
使用し、さらに所望に応じ界面活性剤を添加し
て、古紙を低温にて蒸解する方法である。
本発明は蒸解処理すなわち脱墨温度を低温で行
うことが一つの特徴である。この蒸解処理温度と
しては、一般的には常温付近の温度から100℃ま
であるが、常温付近の温度では処理時間が長時間
となり、また使用されているインクの種類によつ
ては充分に脱色出来ない場合があり、必ずしも充
分でなく、一方、100℃に近い様な高温度ではア
ルカリ剤による着色が起こることがあり、これま
た好ましくないことがある。したがつて、通常は
40〜80℃の範囲であり、実際の蒸解処理工程時間
との関係および上記した点等から、50〜75℃程度
の範囲が好適である。また、処理時間について
は、古紙の種類、処理温度等によつて異なり一概
に決めることはできないが、たとえば通常の印刷
古紙では、処理温度が60℃の場合３〜５時間であ
る。また、本発明の方法は上記の様に低温で実施
されることから蒸解の釜圧は低く通常0.5Kg／cm2
前後である。
本発明において使用される亜二チオン酸塩は、
具体的には亜二チオン酸ソーダであり、ぎ酸ソー
ダ法によつて得られる亜二チオン酸ソーダ、ある
いはボロール法、すなわち水素化ホウ素ナトリウ
ム、荷性ソーダおよび重亜硫酸ソーダを反応させ
て得られる亜二チオン酸ソーダ、またはこれらの
亜二チオン酸ソーダを主成分とする配合品などが
あり、さらに亜二チオン酸塩のホルマリン付加物
（ロンガリツト）をも包含する。
本発明においては亜二チオン酸塩に代えて二酸
化チオ尿素、または二酸化チオ尿素を主成分とす
る配合品などが使用される。これら亜二チオン酸
塩および二酸化チオ尿素は、古紙の種類、処理温
度等によつて異なるが、一般的には、古紙絶乾重
量に対し0.2〜2.0％（wt）の範囲で使用される。
また、アルカリ剤としては、ナトリウム、カリ
ウム等のアルカリ金属の水酸化物、炭酸塩、カル
シウム、マグネシウム、バリウム等のアルカリ土
類金属の水酸化物、炭酸塩およびケイ酸塩等であ
り、それぞれ単独または混合物で使用される。通
常使用されるアルカリ剤は、荷性ソーダ、炭酸ソ
ーダである。
アルカリ剤の使用量は、古紙の種類、処理温度
等によつて異なるが、一般的に古紙絶乾重量に対
し0.2〜2.0％（wt）の濃度範囲である。
また、本発明においてはさらに所望に応じ界面
活性剤が使用される。界面活性剤を使用すること
により、アルカリ剤の浸透性が良くなり、古紙の
離解性が向上すると共に、脱墨効果も向上するの
で、古紙の種類によつては界面活性剤を使用する
ことが好ましい。
この様な効果をもたらす界面活性剤としては、
通常脱墨に使用されているノニオン系、アニオン
系のものが挙げられ、ノニオン系界面活性剤とし
ては、たとえば、ポリオキシエチレンアルキルフ
エニルエーテル、ポリオキシエチレンアルキルエ
ーテルなどであり、アニオン系界面活性剤として
は、たとえば、脂肪酸石けん、アルキルベンセン
スルホン酸塩、高級アルコール硫酸エステル塩な
どである。これらの界面活性剤の使用量は古紙絶
乾重量に対し0.05〜0.5％（wt）で使用されるの
が一般的である。
本発明において、古紙処理濃度としては、薬液
の浸透状態を考慮して一般には５〜40％、好まし
くは10〜30％とされる。
本発明の方法は、従来の高温加圧蒸解釜を使用
する方法がそのまま適用される。
ここで、本発明の方法に使用される薬剤を用い
た実施態様を簡単に説明すると、加圧蒸解釜に、
印刷古紙、清水または白水、アルカリ剤、さらに
所望に応じ界面活性剤を添加し、亜二チオン酸塩
または二酸化チオ尿素を順次投入し、蒸解釜を密
閉後回転させながら蒸気を導入して加温して蒸解
処理を開始し、所定温度に達した後蒸気の導入を
止め、さらに所定時間釜を回転させて蒸解を完了
する。
本発明の方法では、亜二チオン酸塩または二酸
化チオ尿素は、印刷古紙、清水または白水、アル
カリ剤と共に最初から使用してもよいが、これら
の薬剤は本来古紙およびインクとの反応速度が速
く、通常30〜60分で反応が完了する。しかし、40
℃より低い温度では反応性が不充分であり充分な
漂白、脱色の効果が発揮され難い。したがつて古
紙、アルカリ剤および水と共に最初から亜二チオ
ン酸塩または二酸化チオ尿素を添加した場合、古
紙およびインクが充分に軟化されていない状態で
反応が進行することになりロスが大きく、充分な
効果を発揮することができず、脱色が不充分とな
り、また未脱色インクが古紙に再度付着し製品の
白色度低下、色調悪化を来す場合がある。
したがつて、亜二チオン酸塩または二酸化チオ
尿素の効果を充分に発揮させるには、40〜80℃の
範囲の所定の蒸解処理温度に達した後、蒸解処理
終了30分前までの間にこれらを添加することが好
ましい。
以上の様にして蒸解釜で脱墨された古紙は釜下
のピツトに排出され、清水または白水にて古紙濃
度２％前後に希釈される。つづいて離解処理され
た後、フローテーターまたはウオツシヤーにより
古紙とインクが分離される。その後、常法により
次亜塩素酸ソーダまたは過酸化水素にて漂白した
後、再度ウオツシヤー、スクリーンにより異物を
除去した後チエストに送られ脱墨および漂白は完
了する。
〔発明の効果〕
本発明の方法によれば、従来法に比べて著しく
低温で処理出来ることから繊維の損傷が少なく、
このため(1)紙力が向上し抄紙機、加工機等におけ
る紙切れが著しく減少し作業性が向上する。
(2)最近の排水規制の強化により凝集沈澱処理だ
けでは対応しきれなくなつてきているが、本発明
によれば汚濁発生量が著しく減少するため、排水
中のCODが低く、多大な投資も必要でなく又増
産も可能となる。(3)歩留りが向上する。(4)白度が
向上する。(5)さらに従来の高温、高圧法の場合、
蒸解終了後加圧蒸気をブローする必要があり、こ
の時の騒音と悪臭がひどく、公害の原因となつて
いるが、本発明の方法の場合、40〜80℃の様な低
温で蒸解処理を行うことからこれらの問題が全く
発生しない。
さらに、本発明の方法の場合は従来方法に比べ
著しく低温で蒸解できることからエネルギーコス
ト（蒸気コスト）が従来法の1/2〜1/3に節減でき
る。以上のように本発明の方法によれば、再生古
紙の品質の向上と公害問題の解決を同時に達成す
ることができ、かつ経済的にも有利に実施するこ
とができ、工業的に極めて意義ある方法である。
次に発明の実施例を比較例と共に記す。
実施例、比較例において、白色度はJIS P8123
により、色調は色差計（東京電色(株)）により測定
した。〔Ｌは明度、ａは（＋）赤味、（−）は緑
味、ｂは（＋）黄味、（−）は青味をそれぞれ示
す。〕破裂強さはJIS Ｐ 8112により、CODは
JIS Ｋ 0102の試験法によりそれぞれ測定した。
残インク面積率は一定の範囲内に占めるインク面
積を％で表したものである。また、以下の例で示
す薬剤の添加量は古紙絶乾重量に対する重量％で
示した。
実施例１、および比較例１
回転式蒸解釜に色土古紙および模造古紙を７：
３の割合で投入した後、処理濃度30％になる様に
清水を注入した。次いでNaOH １％、Na2CO3
0.5％および亜二チオン酸ソーダ0.5％を順次投入
し、密閉した後蒸気（約0.5Kg／cm2）を通気しな
がら１回転／分の割合で釜を回転させた。温度が
60℃に達したところで（約２時間経過後）蒸気の
通気を止め、引続き約３時間回転を行つた。蒸解
処理に要したトータル時間は約５時間であつた。
蒸解終了後、処理した古紙をチエストに排出
し、白水にて古紙濃度約２％に希釈した。次いで
離解機、スクリーン、洗浄機を通した後、古紙濃
度10％に脱水し、NaClO １％（有効塩素とし
て）、常温、３時間の条件にて漂白し、さらに、
洗浄、スクリーンにて異物を除去し古紙再生パル
プを得た。なお、比較のために従来法による蒸解
を行つた。（比較例１）実施例１と同様な蒸解釜
に古紙、水を投入した後、Na2SO3 2.6％、
Na2CO3 0.25％を投入し、密閉した後蒸気（約３
Kg／cm2）を約３時間、釜を回転させながら通気し
た後、蒸気の通気を止め引続き２時間回転を行つ
て蒸解を完了した。その後の操作は実施例１と同
様に行つて古紙再生パルプを得た。この結果を表
１に示す。
実施例 ２
実施例１の亜二チオン酸ソーダの代わりに二酸
化チオ尿素0.3％を使用した以外は実施例１と同
様に実施した。この結果を表１に示す。
実施例 ３
実施例１において、亜二チオン酸ソーダの投入
時期を蒸解終了１時間前に行つた以外は実施例１
と同様に実施した。結果を表１に示す。
[Industrial Application Field] The present invention relates to a method for recycling waste paper, and more specifically, the present invention does not use sodium sulfite, generates less pollution by a cooking method, and therefore has an extremely low wastewater COD. Good disintegration of waste paper,
This invention relates to a method for recycling waste paper that produces recycled pulp with high whiteness and high strength with little damage to waste paper fibers. [Prior art and its problems] Recovered paper accounts for approximately 40% of the raw material used in paper manufacturing, and together with raw wood, is an important pulp resource. However, the recent tightening of the global raw wood situation and rising energy costs have made recycling of used paper more important. increasing sex. Among these, the deinking and recycling of used printed paper is attracting attention as an advanced use of used paper, and there is a strong demand for the development of efficient deinking technology. There are two typical conventional deinking methods for used printed paper: (1) high-temperature pressure cooking and (2) pulping. Among these methods, the high-temperature pressure cooking method is a method that has been used for a long time, and uses waste paper as a raw material, sodium sulfite, alkaline agent, etc. in a spherical pressure cooker.
A chemical consisting of a surfactant is added and heated at high temperature and pressure (approx.
Cooking is performed while rotating the pot at a temperature of 120℃ to 150℃, followed by disintegration treatment, followed by dedusting to remove foreign substances, cleaning, and further addition of hydrogen peroxide and hypochlorite as necessary. It is bleached with an oxidizing agent such as acid soda and made into recycled pulp. However, in this method, the waste paper fibers are severely damaged due to the high temperature and high pressure treatment, resulting in (1) a decrease in paper strength; (2) Poor yield. (3) High wastewater COD. Also, since the temperature is high, (4) energy costs are required. (5) Equipment costs are high because a pressure cooker is required. In addition, when high-pressure steam is blown after the completion of deinking, there are various drawbacks such as excessive noise and bad odor, which often leads to pollution problems. In particular, wastewater COD regulations are becoming stricter year by year, and wastewater COD countermeasures have become a top priority for factories that rely only on coagulation and sedimentation treatment.
Therefore, in order to improve these drawbacks, many places are taking measures such as lowering the cooking temperature. However, as a chemical solution, generally sodium sulfite is
Since a chemical solution consisting of 3% soda ash and 0.5-1.0% soda ash is used, there is naturally a limit to the reduction in cooking temperature, which is said to be 100-120°C. If the cooking temperature is lowered further, the decolorization of the ink will be poor and deinking will become impossible. Another disadvantage is that the disintegration properties of waste paper deteriorate and a large amount of disintegrated fibers are produced. Therefore, low-temperature cooking is not possible as long as sodium sulfite is used. On the other hand, one method for reducing wastewater COD is to use sodium percarbonate instead of the conventional sodium sulfite. (Japanese Unexamined Patent Publication No. 192792/1983) However, in this method, the cooking temperature is still high at 90 to 180°C, and damage to the waste paper fibers is difficult to avoid.
It also has poor disaggregation properties. Also, the wastewater COD does not decrease as much as expected. Furthermore, a method of digesting waste paper using sodium sulfite and hydrosulfite is known (Japanese Patent Laid-Open Publication No. 36362/1983). As clearly understood from the description in the publication, this method is a method that applies the conventional high-temperature and pressure cooking method as is, and uses a reducing bleaching agent such as hydrosulfite along with sodium sulfite as a chemical, and the cooking process The method is conventionally performed at high temperature and high pressure. Therefore, damage to waste paper fibers is unavoidable, and in addition, the amount of wastewater pollution is large and the wastewater COD is high. In addition, according to the description in Japanese Patent Publication No. 51-36362,
60 using sodium sulfite, hydrosulfite
When cooking at a low temperature such as ℃, bleaching with hydrosulfite, as shown in the comparative example below,
Although the effect of decolorization is recognized, the disintegration and deinking effects of waste paper in the waste paper digestion method using sodium sulfite are greatly affected by temperature, so the disintegration of waste paper deteriorates significantly, and the reject rate (the amount of disintegrated waste paper) ) increases, the percentage of ink remaining on the product also increases significantly. [Problems to be Solved by the Invention] The present invention takes advantage of the advantages of the cooking method in view of the disadvantages of the conventional method of deinking and recycling waste paper by the cooking method, which is carried out under high temperature and high pressure, as described above. High-whiteness, high-strength recycling that reduces the amount of pollution generated, lowers wastewater COD, has good disintegrability of waste paper, and uses ink that shows strong resistance to alkaline chemicals.It is excellent in decolorizing ink from waste paper. It's about getting the pulp. When using the cooking method, the amount of pollution generated is reduced,
In order to obtain recycled waste paper with high whiteness and high strength,
First, it is necessary to lower the cooking temperature to minimize damage to waste paper fibers. Therefore, the present inventors have conducted extensive research into a method for simultaneously achieving deinking and fiber disintegration using a conventional pressure digester and using an alkaline agent and a surfactant at a low temperature below 100°C. As a result, it was found that by saponifying the ink with an alkali and emulsifying and dispersing it with a surfactant, the ink can be separated from the fibers to some extent and dispersed, and at the same time the fibers can be disaggregated. However, alkali alone was insufficient to remove the ink, which is highly resistant to alkaline chemicals used in multicolor printed waste paper, and recycled waste paper was obtained which was colored by residual color. Therefore, if a large amount of alkali is used to remove these inks, the waste paper fibers will be damaged even if cooked at low temperatures, and the whiteness will be reduced due to increased wastewater COD, decreased yield, and alkali coloration of the fibers. It was found that a decrease occurred. [Means for solving the problem] Therefore, the present inventors performed deinking and disintegration using the minimum necessary amount of alkaline agent, and at the same time used a strong reducing agent such as dithionite or thiourea dioxide. death,
By simultaneously performing reductive decolorization of colored ink, which has strong resistance to alkaline chemicals, and bleaching of waste paper fibers, the amount of contamination generated is significantly lower than that of conventional cooking methods, and the product has high whiteness and high strength. The present invention was completed by discovering that it is possible to obtain recycled pulp. That is, the present invention uses a chemical consisting of either dithionite or thiourea dioxide and an alkaline agent, without using sodium sulfite, and further adds a surfactant as desired. , a method of digesting waste paper at low temperatures. One feature of the present invention is that the cooking treatment, that is, the deinking temperature, is performed at a low temperature. The temperature for this cooking process generally ranges from around room temperature to 100°C, but at temperatures around room temperature the processing time takes a long time, and depending on the type of ink used, it may not be possible to remove the color sufficiently. On the other hand, at high temperatures close to 100° C., coloration may occur due to the alkali agent, which is also undesirable. Therefore, usually
The temperature is in the range of 40 to 80°C, and a range of about 50 to 75°C is preferable in view of the relationship with the actual cooking process time and the above-mentioned points. Further, the processing time varies depending on the type of waste paper, the processing temperature, etc., and cannot be determined unconditionally, but for example, for ordinary printed waste paper, the processing time is 3 to 5 hours when the processing temperature is 60°C. In addition, since the method of the present invention is carried out at low temperatures as mentioned above, the cooking pot pressure is low, usually 0.5 kg/cm 2
Before and after. The dithionite salt used in the present invention is
Specifically, it is sodium dithionite, which is obtained by the sodium formate method, or by the borole method, that is, by reacting sodium borohydride, sodium hydroxide, and sodium bisulfite. These include sodium dithionite and combination products containing sodium dithionite as a main component, and also include formalin adducts of dithionite (Rongalit). In the present invention, thiourea dioxide or a compound containing thiourea dioxide as a main component is used instead of dithionite. These dithionite and thiourea dioxide vary depending on the type of waste paper, processing temperature, etc., but are generally used in a range of 0.2 to 2.0% (wt) based on the absolute dry weight of the waste paper. In addition, alkaline agents include hydroxides of alkali metals such as sodium and potassium, carbonates, hydroxides, carbonates, and silicates of alkaline earth metals such as calcium, magnesium, and barium, each of which can be used individually. or used in mixtures. Commonly used alkaline agents are sodium chloride and soda carbonate. The amount of alkaline agent used varies depending on the type of waste paper, processing temperature, etc., but is generally in a concentration range of 0.2 to 2.0% (wt) based on the absolute dry weight of the waste paper. Furthermore, in the present invention, a surfactant may be used as desired. Using a surfactant improves the permeability of the alkaline agent, improves the disintegration properties of waste paper, and also improves the deinking effect, so depending on the type of waste paper, it may be possible to use a surfactant. preferable. Surfactants that bring about this effect include:
Examples of nonionic surfactants include nonionic and anionic surfactants that are usually used for deinking. Examples of nonionic surfactants include polyoxyethylene alkyl phenyl ether and polyoxyethylene alkyl ether. Examples of the agent include fatty acid soaps, alkylbensene sulfonates, and higher alcohol sulfate ester salts. The amount of these surfactants used is generally 0.05 to 0.5% (wt) based on the bone dry weight of waste paper. In the present invention, the waste paper treatment concentration is generally 5 to 40%, preferably 10 to 30%, taking into account the penetration state of the chemical solution. The method of the present invention can be applied directly to a conventional method using a high-temperature pressure digester. Here, to briefly explain an embodiment using a drug used in the method of the present invention, in a pressure digester,
Add printed waste paper, fresh water or white water, an alkaline agent, and a surfactant if desired, and sequentially add dithionite or thiourea dioxide.After sealing the digester, steam is introduced while rotating and heated. The cooking process is started, and after reaching a predetermined temperature, the introduction of steam is stopped, and the cooker is further rotated for a predetermined time to complete the cooking. In the method of the present invention, dithionite or thiourea dioxide may be used initially together with the printed waste paper, fresh water or white water, and an alkaline agent, but these agents inherently have a fast reaction rate with the waste paper and ink. , the reaction is usually completed in 30 to 60 minutes. But 40
At temperatures lower than °C, the reactivity is insufficient and sufficient bleaching and decolorizing effects are difficult to exhibit. Therefore, if dithionite or thiourea dioxide is added from the beginning together with waste paper, an alkaline agent, and water, the reaction will proceed before the waste paper and ink have been sufficiently softened, resulting in large losses and In some cases, the decolorization is insufficient, and the undecolorized ink re-adheres to the waste paper, resulting in a decrease in the whiteness and deterioration of the color tone of the product. Therefore, in order to fully demonstrate the effects of dithionite or thiourea dioxide, it is necessary to use it within 30 minutes before the end of the cooking process after reaching the specified cooking temperature in the range of 40 to 80°C. It is preferable to add these. The waste paper that has been deinked in the digester as described above is discharged into a pit under the cooker, and is diluted with fresh water or white water to a waste paper concentration of around 2%. After a subsequent disaggregation treatment, the waste paper and ink are separated using a floatator or washer. After that, it is bleached with sodium hypochlorite or hydrogen peroxide in a conventional manner, and foreign matter is removed using a washer and screen again, and then sent to CHEST, where deinking and bleaching are completed. [Effects of the Invention] According to the method of the present invention, the treatment can be performed at a significantly lower temperature than conventional methods, so there is less damage to the fibers.
Therefore, (1) paper strength is improved, paper breakage in paper machines, processing machines, etc. is significantly reduced, and work efficiency is improved. (2) Due to the recent tightening of wastewater regulations, coagulation and sedimentation treatment alone is no longer sufficient. However, according to the present invention, the amount of pollution generated is significantly reduced, the COD in wastewater is low, and a large amount of investment is required. It is not necessary and production can be increased. (3) Yield is improved. (4) Whiteness is improved. (5) Furthermore, in the case of the conventional high temperature and high pressure method,
It is necessary to blow pressurized steam after the cooking is completed, which causes severe noise and bad odor and causes pollution, but in the case of the method of the present invention, the cooking process is carried out at a low temperature of 40 to 80 degrees Celsius. None of these problems arise from doing so. Furthermore, in the case of the method of the present invention, cooking can be performed at a significantly lower temperature than in the conventional method, so that the energy cost (steam cost) can be reduced to 1/2 to 1/3 of the conventional method. As described above, according to the method of the present invention, it is possible to simultaneously improve the quality of recycled waste paper and solve the problem of pollution, and it can also be carried out economically, which is extremely significant industrially. It's a method. Next, examples of the invention will be described together with comparative examples. In the examples and comparative examples, the whiteness is JIS P8123.
The color tone was measured using a color difference meter (Tokyo Denshoku Co., Ltd.). [L indicates lightness, a indicates (+) redness, (-) indicates greenness, b indicates (+) yellowness, and (-) indicates bluishness. ] Bursting strength is according to JIS P 8112, COD is
Each was measured according to the test method of JIS K 0102.
The remaining ink area ratio is the ink area occupied within a certain range expressed in %. In addition, the amounts of the chemicals added in the following examples are expressed in weight % based on the bone dry weight of the waste paper. Example 1 and Comparative Example 1 Colored soil waste paper and imitation waste paper were placed in a rotary digester at 7:
After adding water at a ratio of 3.3%, fresh water was injected to give a treatment concentration of 30%. Then NaOH 1 % , Na2CO3
0.5% and sodium dithionite 0.5% were sequentially added, and after the kettle was sealed, the kettle was rotated at a rate of 1 revolution/min while venting steam (approximately 0.5 Kg/cm 2 ). temperature
When the temperature reached 60°C (after about 2 hours), the ventilation of steam was stopped, and rotation was continued for about 3 hours. The total time required for the cooking process was about 5 hours. After completion of the digestion, the treated waste paper was discharged into CHEST and diluted with white water to a waste paper concentration of about 2%. After passing through a disintegrator, screen, and washer, the waste paper is dehydrated to a concentration of 10%, bleached with 1% NaClO (as available chlorine) at room temperature for 3 hours, and further,
Foreign matter was removed by washing and a screen to obtain recycled pulp from used paper. For comparison, cooking was carried out using a conventional method. (Comparative Example 1) After putting waste paper and water into the same digester as in Example 1, Na 2 SO 3 2.6%,
After adding 0.25% Na 2 CO 3 and sealing, steam (approximately 3
Kg/cm 2 ) was aerated for about 3 hours while rotating the pot, and then the steam ventilation was stopped and rotation was continued for 2 hours to complete the cooking. The subsequent operations were carried out in the same manner as in Example 1 to obtain recycled pulp from used paper. The results are shown in Table 1. Example 2 The same procedure as in Example 1 was carried out except that 0.3% of thiourea dioxide was used instead of sodium dithionite. The results are shown in Table 1. Example 3 Same as Example 1 except that sodium dithionite was added one hour before the end of cooking.
It was carried out in the same way. The results are shown in Table 1.
【表】【table】
【表】
実施例４および比較例２
実施例１および比較例１におけるそれぞれの薬
剤に、さらにポリオキシエチレンアルキルフエニ
ルエーテル（商品名 エスノーン HU100 里
田化工(株)製）を0.2％添加した以外は実施例１お
よび比較例１と同様に実施した。この結果を表２
に示す。[Table] Example 4 and Comparative Example 2 Except for adding 0.2% of polyoxyethylene alkyl phenyl ether (trade name: ESNON HU100, manufactured by Satoda Kako Co., Ltd.) to each drug in Example 1 and Comparative Example 1. It was carried out in the same manner as in Example 1 and Comparative Example 1. Table 2 shows the results.
Shown below.
【表】【table】
【表】
比較例 ３および４
従来法（特公昭51−36362号公報に記載の実施
例１の方法）および本発明と同様に低温とした以
外は特公昭51−36362号公報の記載に準じた方法
により実施した。すなわち、実施例１と同様な蒸
解釜に古紙、水を投入した後Na2SO3 5.0％、ト
リポリリン酸ソーダ1.0％、亜二チオン酸ソーダ
2.0％を順次投入した後、密閉し釜を回転しなが
ら５Kg／cm2（高温）または0.5Kg／cm2（低温）の
蒸気を３時間または１時間通気した。その後蒸気
の通気を止め引続き２時間または４時間回転し蒸
解を終了した。その後の操作は実施例１と同様に
行つた。この結果を表３に示す。[Table] Comparative Examples 3 and 4 Conventional method (the method of Example 1 described in Japanese Patent Publication No. 51-36362) and the method described in Japanese Patent Publication No. 51-36362 except that the temperature was lowered as in the present invention. It was carried out by the method. That is, after putting waste paper and water into the same digester as in Example 1, 5.0% Na 2 SO 3 , 1.0% sodium tripolyphosphate, and sodium dithionite were added.
After sequentially adding 2.0%, the pot was sealed and steam of 5 Kg/cm 2 (high temperature) or 0.5 Kg/cm 2 (low temperature) was aerated for 3 hours or 1 hour while rotating the pot. Thereafter, the ventilation of steam was stopped and the cooking was continued for 2 or 4 hours to complete the cooking. The subsequent operations were performed in the same manner as in Example 1. The results are shown in Table 3.
【表】【table】
【表】
実施例 ５
実施例１において、亜二チオン酸ソーダの投入
時期を蒸解処理温度到達時点、蒸解処理の中間点
および蒸解終了30分前に行つた以外は実施例１と
同様に実施した。この結果を表４に示す。
実施例６および比較例５
実施例１および実施例２における、亜二チオン
酸ソーダおよび二酸化チオ尿素の添加量を０〜２
％と変化させ、かつそれらの投入時期を蒸解終了
１時間前に行つた以外は実施例１と同様に実施し
た。結果を表５に示す。
実施例 ７
実施例３の蒸解温度を常温（18℃）〜80℃と変
化させた以外は実施例３と同様に実施した。この
結果を表６に示す。[Table] Example 5 The same procedure as in Example 1 was carried out except that sodium dithionite was added at the time when the cooking temperature was reached, at the midpoint of the cooking process, and at 30 minutes before the end of the cooking process. . The results are shown in Table 4. Example 6 and Comparative Example 5 The amounts of sodium dithionite and thiourea dioxide in Example 1 and Example 2 were varied from 0 to 2.
The same procedure as in Example 1 was carried out except that the ingredients were added 1 hour before the end of cooking. The results are shown in Table 5. Example 7 The same procedure as in Example 3 was carried out except that the cooking temperature in Example 3 was changed from room temperature (18°C) to 80°C. The results are shown in Table 6.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
す。
【represent.
Claims (1)
チオ尿素とアルカリ剤とからなる薬剤を用い、亜
硫酸ソーダを使用することなく、古紙を40〜80℃
の温度で蒸解することを特徴とする古紙の再生方
法。 ２ 上記薬剤に加え、さらに界面活性剤を添加す
ることを特徴とする請求項第１項記載の方法。 ３ 亜二チオン酸塩または二酸化チオ尿素を、蒸
解処理温度到達後、蒸解終了30分前までの間に添
加することを特徴とする請求項第１項記載の方
法。[Claims] 1. Using a chemical consisting of dithionite and an alkaline agent, or thiourea dioxide and an alkaline agent, and without using sodium sulfite, waste paper is heated to 40 to 80°C.
A method for recycling waste paper characterized by digestion at a temperature of . 2. The method according to claim 1, further comprising adding a surfactant in addition to the above-mentioned drug. 3. The method according to claim 1, wherein the dithionite or thiourea dioxide is added after the cooking temperature is reached and up to 30 minutes before the end of the cooking.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60036002A JPS61194289A (en) | 1985-02-25 | 1985-02-25 | Regeneration of old paper |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60036002A JPS61194289A (en) | 1985-02-25 | 1985-02-25 | Regeneration of old paper |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61194289A JPS61194289A (en) | 1986-08-28 |
| JPH024717B2 true JPH024717B2 (en) | 1990-01-30 |
Family
ID=12457573
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60036002A Granted JPS61194289A (en) | 1985-02-25 | 1985-02-25 | Regeneration of old paper |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61194289A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5958184A (en) * | 1992-06-10 | 1999-09-28 | Mitsubishi Gas Chemical Company Inc. | Process for producing thiourea dioxide |
| AU660104B2 (en) * | 1992-06-10 | 1995-06-08 | Mitsubishi Gas Chemical Company, Inc. | Process for producing thiourea dioxide and bleaching of papermaking pulp with thiourea dioxide produced thereby |
| WO2001094700A1 (en) * | 2000-06-09 | 2001-12-13 | Ibiden Co., Ltd. | Papermaking sludge processing method and processing device and hardened body |
| JP4721496B2 (en) * | 2000-08-31 | 2011-07-13 | 日本製紙株式会社 | Method for producing recycled pulp |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3118192A1 (en) * | 1981-05-08 | 1982-11-25 | Basf Ag, 6700 Ludwigshafen | Process for de-inking waste paper |
-
1985
- 1985-02-25 JP JP60036002A patent/JPS61194289A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3118192A1 (en) * | 1981-05-08 | 1982-11-25 | Basf Ag, 6700 Ludwigshafen | Process for de-inking waste paper |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61194289A (en) | 1986-08-28 |
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