JP2023048168A - Production method of acylation-modified cellulose fine fiber - Google Patents
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- 229920002678 cellulose Polymers 0.000 title claims abstract description 144
- 239000001913 cellulose Substances 0.000 title claims abstract description 144
- 239000000835 fiber Substances 0.000 title claims abstract description 77
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 15
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims abstract description 70
- 238000006011 modification reaction Methods 0.000 claims abstract description 47
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 40
- 150000005622 tetraalkylammonium hydroxides Chemical class 0.000 claims abstract description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 34
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 8
- 230000004048 modification Effects 0.000 claims description 17
- 238000012986 modification Methods 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 229960001760 dimethyl sulfoxide Drugs 0.000 claims description 12
- 125000004432 carbon atom Chemical group C* 0.000 claims description 11
- ODIGIKRIUKFKHP-UHFFFAOYSA-N (n-propan-2-yloxycarbonylanilino) acetate Chemical compound CC(C)OC(=O)N(OC(C)=O)C1=CC=CC=C1 ODIGIKRIUKFKHP-UHFFFAOYSA-N 0.000 claims description 5
- 239000000243 solution Substances 0.000 description 49
- 206010061592 cardiac fibrillation Diseases 0.000 description 28
- 230000002600 fibrillogenic effect Effects 0.000 description 28
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- 239000007864 aqueous solution Substances 0.000 description 15
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- 125000002252 acyl group Chemical group 0.000 description 13
- VDZOOKBUILJEDG-UHFFFAOYSA-M tetrabutylammonium hydroxide Chemical compound [OH-].CCCC[N+](CCCC)(CCCC)CCCC VDZOOKBUILJEDG-UHFFFAOYSA-M 0.000 description 12
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- 238000000034 method Methods 0.000 description 8
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- -1 halogen ion Chemical class 0.000 description 6
- 239000000203 mixture Substances 0.000 description 6
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- 230000000052 comparative effect Effects 0.000 description 5
- 229910052739 hydrogen Inorganic materials 0.000 description 5
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- 125000005207 tetraalkylammonium group Chemical group 0.000 description 4
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- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
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- 125000001931 aliphatic group Chemical group 0.000 description 3
- 125000003118 aryl group Chemical group 0.000 description 3
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- 238000010008 shearing Methods 0.000 description 3
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 2
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- 125000003438 dodecyl group Chemical group [H]C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])* 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 150000002148 esters Chemical class 0.000 description 2
- YCUBDDIKWLELPD-UHFFFAOYSA-N ethenyl 2,2-dimethylpropanoate Chemical compound CC(C)(C)C(=O)OC=C YCUBDDIKWLELPD-UHFFFAOYSA-N 0.000 description 2
- MEGHWIAOTJPCHQ-UHFFFAOYSA-N ethenyl butanoate Chemical compound CCCC(=O)OC=C MEGHWIAOTJPCHQ-UHFFFAOYSA-N 0.000 description 2
- UIWXSTHGICQLQT-UHFFFAOYSA-N ethenyl propanoate Chemical compound CCC(=O)OC=C UIWXSTHGICQLQT-UHFFFAOYSA-N 0.000 description 2
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000008103 glucose Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002798 polar solvent Substances 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 2
- 238000004448 titration Methods 0.000 description 2
- ZMANZCXQSJIPKH-UHFFFAOYSA-O triethylammonium ion Chemical compound CC[NH+](CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-O 0.000 description 2
- 239000002023 wood Substances 0.000 description 2
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 1
- 235000017491 Bambusa tulda Nutrition 0.000 description 1
- 241001330002 Bambuseae Species 0.000 description 1
- 229920001503 Glucan Polymers 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- HETCEOQFVDFGSY-UHFFFAOYSA-N Isopropenyl acetate Chemical compound CC(=C)OC(C)=O HETCEOQFVDFGSY-UHFFFAOYSA-N 0.000 description 1
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 description 1
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 235000021355 Stearic acid Nutrition 0.000 description 1
- 125000002777 acetyl group Chemical group [H]C([H])([H])C(*)=O 0.000 description 1
- 230000021736 acetylation Effects 0.000 description 1
- 238000006640 acetylation reaction Methods 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
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- 150000001408 amides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000011425 bamboo Substances 0.000 description 1
- 125000003236 benzoyl group Chemical group [H]C1=C([H])C([H])=C(C([H])=C1[H])C(*)=O 0.000 description 1
- JZQAAQZDDMEFGZ-UHFFFAOYSA-N bis(ethenyl) hexanedioate Chemical compound C=COC(=O)CCCCC(=O)OC=C JZQAAQZDDMEFGZ-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 238000010504 bond cleavage reaction Methods 0.000 description 1
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 125000004063 butyryl group Chemical group O=C([*])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 150000001244 carboxylic acid anhydrides Chemical class 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 229920002301 cellulose acetate Polymers 0.000 description 1
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- WGXGKXTZIQFQFO-CMDGGOBGSA-N ethenyl (e)-3-phenylprop-2-enoate Chemical compound C=COC(=O)\C=C\C1=CC=CC=C1 WGXGKXTZIQFQFO-CMDGGOBGSA-N 0.000 description 1
- IYNRVIKPUTZSOR-HWKANZROSA-N ethenyl (e)-but-2-enoate Chemical compound C\C=C\C(=O)OC=C IYNRVIKPUTZSOR-HWKANZROSA-N 0.000 description 1
- FFYWKOUKJFCBAM-UHFFFAOYSA-N ethenyl 2-methylprop-2-enoate Chemical compound CC(=C)C(=O)OC=C FFYWKOUKJFCBAM-UHFFFAOYSA-N 0.000 description 1
- JZRGFKQYQJKGAK-UHFFFAOYSA-N ethenyl cyclohexanecarboxylate Chemical compound C=COC(=O)C1CCCCC1 JZRGFKQYQJKGAK-UHFFFAOYSA-N 0.000 description 1
- CMDXMIHZUJPRHG-UHFFFAOYSA-N ethenyl decanoate Chemical compound CCCCCCCCCC(=O)OC=C CMDXMIHZUJPRHG-UHFFFAOYSA-N 0.000 description 1
- GLVVKKSPKXTQRB-UHFFFAOYSA-N ethenyl dodecanoate Chemical compound CCCCCCCCCCCC(=O)OC=C GLVVKKSPKXTQRB-UHFFFAOYSA-N 0.000 description 1
- UJRIYYLGNDXVTA-UHFFFAOYSA-N ethenyl hexadecanoate Chemical compound CCCCCCCCCCCCCCCC(=O)OC=C UJRIYYLGNDXVTA-UHFFFAOYSA-N 0.000 description 1
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- ZQZUENMXBZVXIZ-UHFFFAOYSA-N ethenyl tetradecanoate Chemical compound CCCCCCCCCCCCCC(=O)OC=C ZQZUENMXBZVXIZ-UHFFFAOYSA-N 0.000 description 1
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- QIQXTHQIDYTFRH-UHFFFAOYSA-N octadecanoic acid Chemical compound CCCCCCCCCCCCCCCCCC(O)=O QIQXTHQIDYTFRH-UHFFFAOYSA-N 0.000 description 1
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- WGYKZJWCGVVSQN-UHFFFAOYSA-O propan-1-aminium Chemical compound CCC[NH3+] WGYKZJWCGVVSQN-UHFFFAOYSA-O 0.000 description 1
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
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- 239000008117 stearic acid Substances 0.000 description 1
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- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 1
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 1
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- KOZCZZVUFDCZGG-UHFFFAOYSA-N vinyl benzoate Chemical compound C=COC(=O)C1=CC=CC=C1 KOZCZZVUFDCZGG-UHFFFAOYSA-N 0.000 description 1
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 description 1
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Abstract
Description
本発明は、アシル化修飾セルロース微細繊維の製造方法に関する。 The present invention relates to a method for producing acylated modified cellulose microfibers.
本出願人は、セルロースの溶解並びにセルロースを解繊したセルノースナノファイバー（セルロース微細繊維）及びその製造方法に関して多数の特許出願を行っている。その中で本願に関連する代表的なものを以下に列挙する。 The present applicant has filed a number of patent applications relating to cellulose dissolution, cellulose nanofibers (cellulose fine fibers) obtained by defibrating cellulose, and methods for producing the same. Among them, representative ones related to the present application are listed below.
セルロースを溶解して修飾セルロースとする特許文献１は、テトラアルキルアンモニウムアセテートと非プロトン性極性溶媒によりセルロースを溶解した後、エステル化及びエーテル化反応して修飾セルロースを製造している。 In Patent Document 1, in which cellulose is dissolved to form modified cellulose, modified cellulose is produced by dissolving cellulose with tetraalkylammonium acetate and an aprotic polar solvent, followed by esterification and etherification reactions.
セルロースを溶解させずに、セルロースナノファイバーに解繊して、修飾セルロースナノファイバーを得る先行技術としては、特許文献２～４がある。 Patent Documents 2 to 4 are prior arts for obtaining modified cellulose nanofibers by defibrating cellulose into cellulose nanofibers without dissolving cellulose.
特許文献２は、テトラアルキルアンモニウムアセテートと非プロトン性極性溶媒によりセルロースを膨潤および／または部分溶解して解繊した後、化学変性して修飾セルロースナノファイバーを製造している。 According to Patent Document 2, cellulose is swollen and/or partially dissolved with a tetraalkylammonium acetate and an aprotic polar solvent, defibrated, and then chemically denatured to produce modified cellulose nanofibers.
特許文献３は、ドナー数２６以上の非プロトン性溶媒と、カルボン酸ビニルエステルまたはアルデヒドとを含む解繊溶液をセルロースに浸透させて修飾セルロース微細繊維を製造している。 Patent Document 3 manufactures modified cellulose fine fibers by infiltrating cellulose with a defibrating solution containing an aprotic solvent with a donor number of 26 or more and a carboxylic acid vinyl ester or aldehyde.
特許文献４は、ドナー数２６以上の非プロトン性溶媒と、カルボン酸ビニルエステル、反応及び／又は解繊促進添加剤として式｛Ｘ－（Ｒ１）（Ｒ２）（Ｒ３）Ｎ＋－Ｒ４－Ｙ（式中、Ｘ－はハロゲンイオン等、Ｒ１～Ｒ３はアルキル基、Ｒ４はアルキレン基、ＹはＯＨ、ＳＨ又はＮＨ２）｝の４級アンモニウム塩を含む解繊溶液をセルロースに浸透させて、修飾セルロース微細繊維を製造している。 Patent Document 4 discloses an aprotic solvent having a donor number of 26 or more, a carboxylic acid vinyl ester, and a reaction and/or fibrillation promoting additive of the formula { X- (R1)(R2)(R3)N + -R4-Y (Wherein, X- is a halogen ion, etc., R1 to R3 are alkyl groups, R4 is an alkylene group, Y is OH, SH or NH 2 )}. manufactures modified cellulose microfibers.
本発明は、修飾反応溶液をセルロースに浸透させて、セルロースを微細化解繊すると同時にアシル化修飾することを含むアシル化修飾セルロース微細繊維の製造方法を提供する。 The present invention provides a method for producing acylation-modified cellulose fine fibers, which comprises permeating cellulose with a modification reaction solution to pulverize and defibrate cellulose and simultaneously acylate and modify the cellulose.
本発明者らは、前記課題を達成するため鋭意検討した結果、セルロースを前処理することなく、水酸化テトラアルキルアンモニウム（以下「ＴＡＡＨ」と略記する場合がある。）、水、ジメチルスルホキシド（以下「ＤＭＳＯ」と略記する場合がある。）と、アシル化剤と、を含む修飾反応溶液をセルロースに浸透させて、セルロースをアシル化修飾するとともに微細化することにより、樹脂への分散性に優れたアシル化修飾セルロース微細繊維を効率的に製造する方法を見出した。 As a result of intensive studies to achieve the above object, the present inventors found that tetraalkylammonium hydroxide (hereinafter sometimes abbreviated as "TAAH"), water, dimethyl sulfoxide (hereinafter sometimes abbreviated as "TAAH"), without pretreatment of cellulose. It is sometimes abbreviated as "DMSO".) and an acylating agent, and the cellulose is permeated with a modification reaction solution to acylate and refine the cellulose, resulting in excellent dispersibility in the resin. We have found a method for efficiently producing acylated modified cellulose microfibers.
すなわち本発明は、以下の構成からなることを特徴とし、上記課題を解決するものである。
［１］ 下記式（１）で示される水酸化テトラアルキルアンモニウム、水、ジメチルスルホキシド及びアシル化剤を含む修飾反応溶液をセルロースに浸透させて、セルロースをアシル化修飾し解繊することを含むアシル化修飾セルロース微細繊維の製造方法。
Ｒ４Ｎ＋ＯＨ－ （１）
（式中、Ｒはそれぞれ独立して炭素数が２～４のアルキル基を表す）。
［２］ 下記式（１）で示される水酸化テトラアルキルアンモニウム、水及びジメチルスルホキシドを含む溶液をセルロースに浸透させてセルロースを膨潤及び／又は部分解繊した後、前記溶液にアシル化剤を添加して修飾反応溶液とし、前記膨潤及び／又は部分解繊したセルロースをアシル化修飾し解繊することを含むアシル化修飾セルロース微細繊維の製造方法。
Ｒ４Ｎ＋ＯＨ－ （１）
（式中、Ｒはそれぞれ独立して炭素数が２～４のアルキル基を表す）。
［３］ 前記修飾反応溶液中の水酸化テトラアルキルアンモニウム、水、メチルスルホキシド及びアシル化剤の成分比が、水酸化テトラアルキルアンモニウム、水、メチルスルホキシド及びアシル化剤の総量に対して、水酸化テトラアルキルアンモニウムが０．１～１．２ｗｔ％、水が０．１～１．８ｗｔ％、ジメチルスルホキシドが８２．０～９８．８ｗｔ％、アシル化剤が１．０～１５．０ｗｔ％である、前記［１］又は前記［２］に記載の製造方法。
That is, the present invention is characterized by having the following configurations, and solves the above problems.
[1] Acyl including permeating cellulose with a modification reaction solution containing a tetraalkylammonium hydroxide represented by the following formula (1), water, dimethyl sulfoxide and an acylating agent to acylate and defibrate the cellulose. A method for producing chemically modified cellulose fine fibers.
R 4 N + OH − (1)
(In the formula, each R independently represents an alkyl group having 2 to 4 carbon atoms).
[2] A solution containing a tetraalkylammonium hydroxide represented by the following formula (1), water, and dimethylsulfoxide is permeated into cellulose to swell and/or partially decompose cellulose, and then an acylating agent is added to the solution. A method for producing acylated modified cellulose fine fibers, which comprises acylating and defibrating the swollen and/or partially defiberized cellulose to form a modification reaction solution.
R 4 N + OH − (1)
(In the formula, each R independently represents an alkyl group having 2 to 4 carbon atoms).
[3] The ratio of the components of the tetraalkylammonium hydroxide, water, methylsulfoxide and acylating agent in the modification reaction solution to the total amount of tetraalkylammonium hydroxide, water, methylsulfoxide and acylating agent is 0.1-1.2 wt% of tetraalkylammonium, 0.1-1.8 wt% of water, 82.0-98.8 wt% of dimethyl sulfoxide, and 1.0-15.0 wt% of acylating agent , the production method according to the above [1] or the above [2].
本発明の修飾反応溶液中のＴＡＡＨと水の存在は、修飾反応溶液のセルロースフィブリル同士間への浸透効率を向上することだけでなく、水素結合の切断とアシル化修飾反応を促進することもできる。この二重効果により均一性と解繊度の高いアシル化修飾セルロース微細繊維が得られる。そのため、結晶化度が高く、繊維形状の損傷が少なくてアスペクト比が大きく、且つ溶融混錬により樹脂へのナノ分散ができるセルロース微細繊維を効率良く生産できる。さらに、用途に応じて様々なアシル基を導入し、樹脂などの有機媒体との親和性をさらに向上できる。 The presence of TAAH and water in the modification reaction solution of the present invention not only improves the penetration efficiency of the modification reaction solution between cellulose fibrils, but also promotes hydrogen bond scission and acylation modification reaction. . This dual effect results in acylated modified cellulose microfibers with high uniformity and defibration. Therefore, it is possible to efficiently produce cellulose fine fibers that have a high degree of crystallinity, have a large aspect ratio with little damage to the fiber shape, and can be nano-dispersed in a resin by melt-kneading. Furthermore, various acyl groups can be introduced depending on the application to further improve affinity with organic media such as resins.
さらに、本発明のアシル化修飾セルロース微細繊維の製造法は、水酸化テトラアルキルアンモニウムと水を添加することにより修飾反応時間又は解繊時間を短縮することができる。 Furthermore, in the method for producing acylated modified cellulose fine fibers of the present invention, modification reaction time or fibrillation time can be shortened by adding tetraalkylammonium hydroxide and water.
本発明のセルロース微細繊維の製造方法は、セルロースを機械的破砕や乾燥等の前処理することなく、ＴＡＡＨ、水、ＤＭＳＯと、アシル化剤と、を含む修飾反応溶液をセルロースに浸透させて、セルロースをアシル化修飾するとともにセルロースミクロフィブリルの間の水素結合を切断しミクロフィブリル同士間の相互作用を弱めることによりアシル化セルロース微細繊維を製造することを特徴とする。 In the method for producing cellulose fine fibers of the present invention, the cellulose is permeated with a modification reaction solution containing TAAH, water, DMSO, and an acylating agent without pretreatment such as mechanical crushing or drying. It is characterized by producing acylated cellulose fine fibers by acylating cellulose and cutting hydrogen bonds between cellulose microfibrils to weaken the interaction between microfibrils.
また、本発明のセルロース微細繊維の製造方法は、セルロースの解繊がある程度進んでからアシル化剤を加えてもよい。すなわち、ＴＡＡＨ、水及びＤＭＳＯを含む溶液（以下「解繊溶液」という。）をセルロースに浸透させてセルロースを膨潤及び／又は部分解繊した後、前記溶液にアシル化剤を添加して修飾反応溶液とし、前記膨潤及び／又は部分解繊したセルロースをアシル化修飾するとともにセルロースミクロフィブリルの間の水素結合を切断することによりアシル化セルロース微細繊維を製造することができる。 In addition, in the method for producing cellulose fine fibers of the present invention, the acylating agent may be added after defibration of cellulose has progressed to some extent. That is, a solution containing TAAH, water and DMSO (hereinafter referred to as "fibrillation solution") is permeated into cellulose to swell and/or partially defiberize the cellulose, and then an acylating agent is added to the solution to perform a modification reaction. Acylated cellulose fine fibers can be produced by making a solution and subjecting the swollen and/or partially decomposed cellulose to acylation modification and breaking hydrogen bonds between cellulose microfibrils.
アシル化剤を添加した修飾反応溶液のセルロースへの浸透性を低下させないため、解繊がある程度進んでから加えることが好ましい。アシル化剤を途中から加えることにより、アシル化反応に先立ってＴＡＡＨ、水とＤＭＳＯを含む溶液をセルロースに充分に浸透させることができ、セルロースのミクロフィブリル同士の間を膨張させたり、ミクロフィブリルの配列を乱れさしたりすることができる。そうすることにより、後に添加するアシル化剤は容易にセルロースのフィブリルに作用し修飾反応の効率と均一性を促進できる。 In order not to reduce the permeability of the modification reaction solution to which the acylating agent is added, it is preferable to add the acylating agent after defibration has progressed to some extent. By adding the acylating agent in the middle, the solution containing TAAH, water and DMSO can be sufficiently permeated into the cellulose prior to the acylation reaction, causing swelling between the microfibrils of the cellulose and the formation of the microfibrils. You can perturb the array. By doing so, the acylating agent added later can easily act on the cellulose fibrils to promote the efficiency and uniformity of the modification reaction.
原料となるセルロースは、セルロース単独の形態であってもよく、リグニンやヘミセルロースなどの非セルロース成分を含む混合形態であってもよい。
好ましいセルロール物質としては、Ｉ結晶型セルロース構造を含むセルロース物質であり、例えば、木材由来パルプ、木材、竹、リンダーパルプ、綿、セルロースパウダーを含む物質等がある。
The raw material cellulose may be in the form of cellulose alone or in a mixed form containing non-cellulose components such as lignin and hemicellulose.
Preferred cellulose materials are those containing type I crystalline cellulose structure, such as materials containing wood derived pulp, wood, bamboo, linder pulp, cotton, cellulose powder, and the like.
前記ＴＡＡＨは、セルロースの水素結合を切断し、フィブリル同士間の水素結合を切断する効果を有している。加えて、塩基性であるためセルロース水酸基のアシル化修飾反応を促進する作用もある。一方、水はＤＭＳＯにおけるＴＡＡＨの安定性及びＤＭＳＯとＴＡＡＨの溶媒和を付与する役割として働くと推測する。 The TAAH has the effect of breaking hydrogen bonds in cellulose and breaking hydrogen bonds between fibrils. In addition, since it is basic, it also acts to promote the acylation modification reaction of cellulose hydroxyl groups. On the other hand, we speculate that water plays a role in conferring the stability of TAAH in DMSO and the solvation of DMSO and TAAH.
本発明に用いる水酸化テトラアルキルアンモニウム（ＴＡＡＨ）は、アルキル基の炭素数が２～４のものであれば何の制限もないが、好ましいＴＡＡＨは、水酸化テトラエチルアンモニウム（ＴＥＡＨ）、水酸化テトラプロピルアンモニウム（ＴＰＡＨ）と水酸化テトラブチルアンモニウム（ＴＢＡＨ）である。ＴＡＡＨは、水を含んだ方が安定性が高く、加えて、水は修飾反応溶液の成分であるため、ＴＡＡＨは水溶液の状態で利用できる。その中でも、ＴＥＡＨ、ＴＰＡＨ、ＴＢＡＨは、市販の薬品が水溶液で市販されており入手が容易である。前記水酸化テトラアルキルアンモニウムは、単独で用いてもよく、２種以上を混合して用いてもよい。 The tetraalkylammonium hydroxide (TAAH) used in the present invention is not particularly limited as long as the alkyl group has 2 to 4 carbon atoms. propylammonium (TPAH) and tetrabutylammonium hydroxide (TBAH). TAAH is more stable when it contains water, and in addition, since water is a component of the modification reaction solution, TAAH can be used in the form of an aqueous solution. Among them, TEAH, TPAH, and TBAH are commercially available chemicals in the form of aqueous solutions and are readily available. The tetraalkylammonium hydroxides may be used alone or in combination of two or more.
一方、水酸化テトラメチルアンモニウムは塩基性を有するもののセルロースの膨張又は解繊を促進する効果が無かった。また、ブチル基より側鎖の長いテトラアルキルアンモニウムは塩基性とＤＭＳＯへの溶解性は低く、セルロースの解繊と修飾を促進する効果が低いため好ましくない。 On the other hand, although tetramethylammonium hydroxide has basicity, it did not have the effect of promoting expansion or fibrillation of cellulose. In addition, tetraalkylammonium having a longer side chain than a butyl group is not preferable because it is low in basicity and solubility in DMSO, and is low in the effect of promoting the defibration and modification of cellulose.
本発明に用いるアシル化剤としては、カルボン酸ビニルエステル、カルボン酸無水物及びカルボン酸などがあるが、反応効率を維持し副反応を抑えるためカルボン酸ビニルが最も好ましい。これらのアシル化剤は、単独で又は二種以上を組み合わせて使用できる。 The acylating agent used in the present invention includes vinyl carboxylates, carboxylic acid anhydrides, carboxylic acids and the like, but vinyl carboxylate is most preferable in order to maintain reaction efficiency and suppress side reactions. These acylating agents can be used alone or in combination of two or more.
カルボン酸ビニルエステルとしては、下記式（２）で表されるカルボン酸ビニルエステルを用いることができる。
Ｒ１－ＣＯＯ－Ｃ（Ｒ２）＝Ｃ（Ｒ３）（Ｒ４） （２）
（式中、Ｒ１は炭素数１～１６のアルキル基、アルキレン基シクロアルキル基及びアリール基のいずれかを表わし、Ｒ２，Ｒ３，Ｒ４は水素または炭素数１～１６のアルキル基、アルキレン基シクロアルキル基及びアリール基のいずれかを表わす。）
As the carboxylic acid vinyl ester, a carboxylic acid vinyl ester represented by the following formula (2) can be used.
R1-COO-C(R2)=C(R3)(R4) (2)
(Wherein, R1 represents any one of an alkyl group having 1 to 16 carbon atoms, an alkylene group cycloalkyl group and an aryl group; represents either a group or an aryl group.)
さらに、前記カルボン酸ビニルエステルが、酢酸ビニル、プロピオン酸ビニル、酪酸ビニル、カプロン酸ビニル、シクロヘキサンカルボン酸ビニル、カプリル酸ビニル、カプリン酸ビニル、ラウリン酸ビニル、ミリスチン酸ビニル、パルミチン酸ビニル、ステアリン酸ビニル、ピバリン酸ビニル、オクチル酸ビニルアジピン酸ジビニル、メタクリル酸ビニル、クロトン酸ビニル、ピバリン酸ビニル、オクチル酸ビニル、安息香酸ビニル、桂皮酸ビニル、酢酸イソプロペニルの群より選択された少なくとも１種であることが好ましい。 Further, the carboxylic acid vinyl ester is vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, stearic acid. at least one selected from the group consisting of vinyl, vinyl pivalate, vinyl octylate, divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl octoate, vinyl benzoate, vinyl cinnamate, and isopropenyl acetate; Preferably.
これらのカルボン酸ビニルは、単独で又は二種以上を組み合わせて使用できる。これらのカルボン酸ビニルのうち、解繊性と反応性の点から、酢酸ビニル、プロピオン酸ビニルと酪酸ビニル等の炭素数２～７（特に２～５）の低級脂肪族カルボン酸ビニルが好ましく、Ｃ１－４アルキルカルボン酸ビニルが特に好ましい。炭素数が大きすぎると、ミクロフィブリル間への浸透性とセルロース水酸基に対する反応性が低下するおそれがあるため、低級脂肪族カルボン酸ビニルと併用することが好ましい。 These vinyl carboxylates can be used alone or in combination of two or more. Among these vinyl carboxylates, lower aliphatic vinyl carboxylates having 2 to 7 carbon atoms (especially 2 to 5 carbon atoms) such as vinyl acetate, vinyl propionate and vinyl butyrate are preferred from the viewpoint of fibrillation and reactivity. Vinyl C1-4 alkyl carboxylate is particularly preferred. If the number of carbon atoms is too large, the permeability between microfibrils and the reactivity to cellulose hydroxyl groups may decrease, so it is preferable to use it together with a lower aliphatic vinyl carboxylate.
本発明の修飾反応溶液は、ＴＡＡＨ、水、ＤＭＳＯとアシル化剤から構成され、その構成比は、ＴＡＡＨが０．１～１．２ｗｔ％、水が０．１～１．８ｗｔ％、ＤＭＳＯが８２～９８．８ｗｔ％、アシル化剤が１～１５ｗｔ％の濃度範囲内になるように調整される。より好ましくは、ＴＡＡＨが０．１５～１．０ｗｔ％、水が０．１５～１．６ｗｔ％、ＤＭＳＯが８５．４～９７．７ｗｔ％、アシル化剤が２～１２ｗｔ％の濃度範囲内になるように調整される。さらに好ましくは、ＴＡＡＨが０．２～０．９ｗｔ％、水が０．２～１．５ｗｔ％、ＤＭＳＯが８５．４～９７．７ｗｔ％、アシル化剤が３～１０ｗｔ％の濃度範囲内になるように調整される。 The modification reaction solution of the present invention is composed of TAAH, water, DMSO, and an acylating agent. 82-98.8 wt%, and the acylating agent is adjusted to be within the concentration range of 1-15 wt%. More preferably, TAAH is 0.15 to 1.0 wt%, water is 0.15 to 1.6 wt%, DMSO is 85.4 to 97.7 wt%, and the acylating agent is within the concentration range of 2 to 12 wt%. adjusted to be More preferably, the concentration of TAAH is 0.2-0.9 wt%, water is 0.2-1.5 wt%, DMSO is 85.4-97.7 wt%, and the acylating agent is 3-10 wt%. adjusted to be
ＴＡＡＨの濃度が０．１ｗｔ％より低くなると解繊と修飾に与える作用は少ないため好ましくない。一方、１．２ｗｔ％より高くなるとセルロースは溶解しＩ型結晶構造を失う恐れがあるため好ましくない。 If the concentration of TAAH is lower than 0.1 wt %, the effect on fibrillation and modification is small, which is not preferable. On the other hand, if the content is higher than 1.2 wt %, the cellulose may dissolve and lose its type I crystal structure, which is not preferable.
水の濃度は０．１ｗｔ％より低くなるとセルロースの解繊度が低下したり、ＴＡＡＨが不安定で分解したりする恐れがあるため好ましくない。一方、１．８ｗｔ％より高くなるとセルロースの解繊度だけでなく、修飾率も低下するため好ましくない。 If the concentration of water is lower than 0.1 wt %, the degree of fibrillation of cellulose may decrease, and TAAH may be unstable and decomposed, which is not preferable. On the other hand, if it is higher than 1.8 wt %, not only the defibration degree of cellulose but also the modification rate is lowered, which is not preferable.
アシル化剤は１ｗｔ％より低くなるとセルロースの解繊度合と修飾率（疎水性効果）が低下する恐れがあるため好ましくない。一方、１５ｗｔ％を超えると修飾反応液のセルロースへの浸透性が悪くなるため解繊度合が低下する恐れがあるため好ましくない。 If the amount of the acylating agent is less than 1 wt %, the degree of fibrillation and modification rate (hydrophobic effect) of cellulose may decrease, which is not preferable. On the other hand, if it exceeds 15 wt %, the permeability of the modification reaction solution to cellulose becomes poor, and the degree of fibrillation may decrease, which is not preferable.
本発明の修飾反応溶液は、ＴＡＡＨ、水、アシル化剤及びＤＭＳＯ以外に、解繊性、修飾反応性に影響を与えない程度であれば、他の有機溶媒を含むこともできる。例えば、Ｎ，Ｎ－ジメチルアセトアミド、Ｎ，Ｎ－ジメチルホルムアミド、Ｎ－メチルピロリトン、ピリジンが他の有機溶媒として挙げられる。 In addition to TAAH, water, an acylating agent, and DMSO, the modification reaction solution of the present invention may contain other organic solvents as long as they do not affect fibrillation properties and modification reactivity. Other organic solvents include, for example, N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrroliton, and pyridine.
修飾反応溶液に添加するセルロースの量は、修飾反応溶液中のアシル化剤の濃度が前記濃度範囲であれば、セルロースに対してアシル化剤が過剰であっても問題はないが、アシル化剤の使用効率が低いため、修飾反応溶液中のアシル化剤１部に対してセルロースが１／５～３部が好ましく、より好ましくは１／３～１部、最も好ましくは、１／２～１部である。 Regarding the amount of cellulose added to the modification reaction solution, if the concentration of the acylating agent in the modification reaction solution is within the above concentration range, there is no problem even if the amount of the acylating agent is excessive relative to the cellulose. is low, the cellulose is preferably 1/5 to 3 parts, more preferably 1/3 to 1 part, most preferably 1/2 to 1 part per 1 part of the acylating agent in the modification reaction solution. Department.
セルロースと修飾反応溶液との重量割合は、修飾反応溶液中のアシル化剤濃度とアシル化剤とセルロースの比率を考慮すると、通常、前者／後者＝０．５／９９．５～２５／７５程度の範囲から選択でき、例えば１／９９～２０／８０、好ましくは１．５／９８．５～１５／８５、さらに好ましくは２／９８～１２／８８程度である。セルロースの割合が少なすぎると、セルロース微細繊維の生産効率が低くなり、多すぎると、修飾反応溶液のセルロース繊維間、ラメラ間およびミクロフィブリル間への浸透が不十分なため解繊度合いが低下する恐れがある。また、セルロースの割合が多いと分散液の粘度が高くなるため反応の均一性が低下する。いずれにしても生産性と品質が低下するおそれがある。さらに、セルロースの割合が多すぎると得られた微細繊維のサイズと修飾率の均一性が低下するおそれがある。 Considering the concentration of the acylating agent in the modification reaction solution and the ratio of the acylating agent to cellulose, the weight ratio of the cellulose to the modification reaction solution is usually about 0.5/99.5 to 25/75. for example, 1/99 to 20/80, preferably 1.5/98.5 to 15/85, more preferably about 2/98 to 12/88. If the proportion of cellulose is too low, the production efficiency of cellulose fine fibers is low. There is fear. In addition, when the proportion of cellulose is high, the viscosity of the dispersion becomes high, resulting in a decrease in the uniformity of the reaction. In either case, productivity and quality may be reduced. Furthermore, if the proportion of cellulose is too high, the uniformity of the size and modification rate of the obtained fine fibers may be lowered.
本発明の解繊溶液又は修飾反応溶液の調製方法は、特に制限しない。例えば、通常市販から購入したＴＡＡＨ水溶液を所望のＴＡＡＨ／水の重量比まで調製した後、解繊溶液であればＤＭＳＯを、修飾反応溶液であればＤＭＳＯとアシル化剤を加えて攪拌することで解繊溶液又は修飾反応溶液が得られる。市販ＴＡＡＨ水溶液がＴＡＡＨの濃度が、水の濃度を最適範囲にしたときに所望濃度より低い場合、使用する前に蒸留し所望水分率まで濃縮してから使用することが好ましい。また、所望濃度より高い場合、水を加え希釈してから使用する。混ぜる時の温度に特に制限しないが、１０～７０℃が好ましい。 The method for preparing the fibrillation solution or modification reaction solution of the present invention is not particularly limited. For example, after preparing an aqueous TAAH solution purchased from a commercial market to a desired TAAH/water weight ratio, add DMSO for a fibrillation solution, or add DMSO and an acylating agent for a modification reaction solution, and stir. A fibrillation solution or modification reaction solution is obtained. If the concentration of TAAH in the commercially available TAAH aqueous solution is lower than the desired concentration when the concentration of water is adjusted to the optimum range, it is preferable to distill and concentrate to the desired moisture content before use. If the concentration is higher than desired, dilute with water before use. Although there is no particular limitation on the temperature during mixing, 10 to 70°C is preferable.
本発明の修飾反応溶液にてセルロースを修飾する方法は、特に制限しない。例えば、既定量の本発明の修飾反応溶液にセルロースを加え、一定な温度と時間で攪拌することでアシル化修飾したセルロース微細繊維の分散液が得られる。攪拌は、通常用いられる機械式撹拌機で攪拌すればよいが、ホモジナイザー等であってもよい。ビーカースケールならマグネティックスターラーの攪拌で十分である。反応温度は、２０～８０℃であればよく、室温で温度調整せずに攪拌させればよい。２０℃より低くなると修飾反応速度が低いため好ましくない。８０℃より高くなるとセルロースやＴＡＡＨが分解したりする恐れがあるため好ましくない。最も好ましくは２０～７０℃である。 The method for modifying cellulose with the modification reaction solution of the present invention is not particularly limited. For example, cellulose is added to a predetermined amount of the modification reaction solution of the present invention, and the mixture is stirred at a constant temperature and time to obtain a dispersion of acylated cellulose fine fibers. Stirring may be performed with a commonly used mechanical stirrer, but a homogenizer or the like may also be used. Stirring with a magnetic stirrer is sufficient for the beaker scale. The reaction temperature may be 20 to 80° C., and the mixture may be stirred at room temperature without adjusting the temperature. If the temperature is lower than 20°C, the modification reaction rate is low, which is not preferable. If the temperature is higher than 80°C, cellulose and TAAH may decompose, which is not preferable. Most preferably it is 20 to 70°C.
本発明での修飾反応時間は、前記修飾反応溶液に含まれるＴＡＡＨとアシル化剤の種類と濃度及び反応温度によって適宜に調整すればよい。例えば０．２～２４時間、好ましくは０．５～１２時間、さらに好ましくは１～８時間程度である。酢酸ビニルなどの低級カルボン酸ビニルを用いる場合、数時間（例えば０．５～５時間）程度の時間であってもよく、好ましくは１～４時間程度である。さらに、前述のように、処理温度（反応温度）を高めたり、攪拌速度を増加したりすることで反応時間を短くしてもよい。この時、カルボン酸ビニルなどの低沸点成分のアシル化剤を含む場合は蒸発を避けるため密閉系統、加圧系統又は還流系統内で行うのが好ましい。反応時間が短すぎると、修飾反応溶液がミクロフィブリル間まで浸透するのが不十分のため、反応が不十分となり、解繊度合いも低下するおそれがある。一方、反応時間が長すぎたり、温度が高すぎたりすることによる過修飾が生じ、セルロース微細繊維の結晶化度と収率が低下するおそれがある。 The modification reaction time in the present invention may be appropriately adjusted depending on the types and concentrations of TAAH and the acylating agent contained in the modification reaction solution and the reaction temperature. For example, it is about 0.2 to 24 hours, preferably 0.5 to 12 hours, more preferably 1 to 8 hours. When a lower vinyl carboxylate such as vinyl acetate is used, the time may be about several hours (eg, 0.5 to 5 hours), preferably about 1 to 4 hours. Furthermore, as described above, the reaction time may be shortened by increasing the treatment temperature (reaction temperature) or increasing the stirring speed. At this time, when an acylating agent of a low boiling point component such as vinyl carboxylate is contained, it is preferable to carry out in a closed system, a pressurized system or a reflux system in order to avoid evaporation. If the reaction time is too short, the modification reaction solution will not sufficiently permeate between the microfibrils, resulting in insufficient reaction and possibly lowering the degree of fibrillation. On the other hand, too long a reaction time or too high a temperature may lead to overmodification, which may reduce the crystallinity and yield of cellulose fine fibers.
アシル化剤を途中から加える場合、第１段階の解繊溶液によりセルロースを膨潤及び／又は部分解繊するのに用いる装置は特に制限しないが、後のアシル化修飾反応／解繊と同じ攪拌装置を備えた装置を使用すればよい。第１段階の膨潤及び／又は部分解繊の時間は、ＴＡＡＨ、水とＤＭＳＯの配合比と攪拌機のせん断力により適宜に調整すればよい。例えば、効率の観点から好ましくは５時間以下、より好ましくは４時間以下、最も好ましくは３時間以下である。
そして、アシル化剤を加えてから前記膨潤及び／又は部分解繊したセルロースをアシル化修飾し解繊するのにさらに０．５～５時間以上反応させることが好ましい。
When the acylating agent is added in the middle, the device used for swelling and/or partially defibrating the cellulose with the fibrillation solution in the first step is not particularly limited, but the same agitating device as the later acylation modification reaction/fibrillation. A device with a The time for swelling and/or partial decomposition in the first stage may be appropriately adjusted according to the mixing ratio of TAAH, water and DMSO and the shearing force of the stirrer. For example, from the viewpoint of efficiency, it is preferably 5 hours or less, more preferably 4 hours or less, and most preferably 3 hours or less.
Then, after the addition of the acylating agent, it is preferable that the swollen and/or partially defiberized cellulose is further reacted for 0.5 to 5 hours or more for acylation modification and defibration.
修飾反応／解繊溶液からアシル化修飾セルロース微細繊維を回収する方法として、修飾反応／解繊溶液を回収しそのまま再利用するか否かにより２つ方法が挙げられるが、特に制限しない。 As a method for recovering the acylated modified cellulose fine fibers from the modification reaction/fibrillation solution, there are two methods depending on whether the modification reaction/fibrillation solution is recovered and reused as it is, but there is no particular limitation.
例えば、修飾反応／解繊溶液を回収しそのまま再利用する場合、反応終了後、遠心分離法、圧搾法、濾過法、沈殿法等の固液分離方法を用いて固形分のアシル化修飾微細繊維と修飾反応／解繊溶液をそれぞれ回収する。回収した修飾反応／解繊溶液を組成調整（例えば、消耗されたアシル化剤を追加する）した後次のアシル化修飾微細繊維の合成に使用できる。
固形分のアシル化修飾微細繊維は、洗浄することで残留した修飾／解繊溶媒を除く。洗浄操作を複数回（例えば、２～５回程度）で行うことによりアシル化修飾セルロース微細繊維が得られる。洗浄溶媒は特に制限しないが、修飾微細繊維以外の成分を解ける有機溶媒であればよい。例えば、水、アルコール類、ケトン類、エステル類、トルエン類などが挙げられる。アセチル基等親水性の高いアシル基で修飾する場合は水やアルコールが特に好ましい。一方、ラウリル基等疎水性の高いアシル基で修飾する場合は、アシル化剤を効率的に除くため、水やアルコールで洗浄した後、アセトン、エステル又はトルエン等極性が低い溶媒で洗浄することが好ましい。
For example, when the modification reaction/fibrillation solution is collected and reused as it is, after the reaction is completed, the solid content of the acylated modified fine fibers is separated using a solid-liquid separation method such as centrifugation, compression, filtration, or precipitation. and the modification reaction/fibrillation solution are collected respectively. The recovered modification reaction/fibrillation solution can be used for subsequent synthesis of acylated modified fibrils after composition adjustment (eg, adding the acylating agent that has been depleted).
The solids acylated modified fibrils are washed to remove residual modification/fibrillation solvent. Acylated modified cellulose fine fibers can be obtained by performing the washing operation a plurality of times (for example, about 2 to 5 times). Although the washing solvent is not particularly limited, any organic solvent capable of dissolving components other than the modified fine fibers may be used. Examples include water, alcohols, ketones, esters, and toluenes. Water and alcohol are particularly preferable when modifying with a highly hydrophilic acyl group such as an acetyl group. On the other hand, when modifying with a highly hydrophobic acyl group such as a lauryl group, in order to efficiently remove the acylating agent, after washing with water or alcohol, washing with a solvent with low polarity such as acetone, ester or toluene is recommended. preferable.
一方、修飾反応／解繊溶液を再利用しない場合、反応終了後、水又はメタノールなどでアシル化剤を失活させてから前記に記述した固液分離により修飾セルロース微細繊維を回収し、前記と同じ洗浄方法と洗浄溶媒により洗浄する。 On the other hand, when the modification reaction/fibrillation solution is not reused, after the reaction is completed, the acylating agent is deactivated with water or methanol, and then the modified cellulose fine fibers are recovered by the solid-liquid separation described above. Wash with the same wash method and wash solvent.
得られたセルロース微細繊維の形状はＦＥ－ＳＥＭを用いて観察することができる。通常、本発明のアシル化修飾セルロース微細繊維の繊維径は数１０～数１００ｎｍ、長さは数μｍ～数十μｍであるが、場合によっては、ミクロンオーダーの微細繊維が含まれることがある。サブミクロンオーダーやミクロンオーダーの微細繊維に含まれるミクロフィブリルは緩く乱れた状態となっているため、せん断力を加えることで数１０ｎｍ以下にナノ化することができる。せん断力を加える装置は特に制限しないが、例えば二軸混錬機、ホモジナイザー、マスコロイダーとペイントシェーカーなどが挙げられる。 The shape of the obtained cellulose fine fibers can be observed using FE-SEM. The acylated modified cellulose fine fibers of the present invention usually have a fiber diameter of several tens to several hundred nm and a length of several μm to several tens of μm, but may contain micron-order fine fibers in some cases. Since microfibrils contained in submicron-order or micron-order fine fibers are in a loosely disordered state, they can be nanoized to several tens of nanometers or less by applying a shearing force. Apparatus for applying a shearing force is not particularly limited, but examples thereof include a twin-screw kneader, a homogenizer, a masscolloider and a paint shaker.
本発明のアシル化修飾セルロース微細繊維の平均置換度（セルロースの基本構成単位であるグルコース当たりの置換された水酸基の平均数）は、用途に応じて反応条件で制御することができる。平均置換度は０．１以下になると解繊度合と得られた微細繊維の疎水性が低いため好ましくない。１．５を超えるとセルロースのI型結晶構造を失う恐れがあるため好ましくない。より好ましくは０．２～１．４である。最も好ましくは０．４～１．３である。なお、平均置換度（ＤＳ：ｄｅｇｒｅｅ ｏｆ ｓｕｂｓｔｉｔｕｔｉｏｎ）は、セルロースの基本構成単位であるグルコース当たりの置換された水酸基の平均数であり、Ｂｉｏｍａｃｒｏｍｏｌｅｃｕｌｅｓ ２００７，８，１９７３－１９７８やＷＯ２０１２／１２４６５２Ａ１又はＷＯ２０１４／１４２１６６Ａ１などを参照できる。 The average degree of substitution of the acylated modified cellulose fine fibers of the present invention (average number of hydroxyl groups substituted per glucose, which is the basic structural unit of cellulose) can be controlled by reaction conditions depending on the application. An average degree of substitution of 0.1 or less is not preferable because the degree of fibrillation and the hydrophobicity of the obtained fine fibers are low. If it exceeds 1.5, the I-type crystal structure of cellulose may be lost, which is not preferable. It is more preferably 0.2 to 1.4. Most preferably it is between 0.4 and 1.3. Incidentally, the average degree of substitution (DS) is the average number of substituted hydroxyl groups per glucose, which is the basic structural unit of cellulose, and is described in Biomacromolecules 2007, 8, 1973-1978, WO2012/124652A1 or WO2014/142166A1. etc. can be referred to.
本発明により作製するセルロース微細繊維は有機溶媒に容易に分散できる。セルロース微細繊維は分散可能の有機溶媒は、アシル基の種類に依存する。例えば、炭素数２～３の脂肪族アシル基で修飾したセルロース微細繊維はアルコール類、アミド類とテトラヒドロフランなどの極性有機溶媒に分散可能である。一方、炭素数４以上の脂肪族アシル基又は芳香族アシル基により修飾したセルロース微細繊維は、極性溶媒から疎水性溶媒まで分散可能である。例えば、ブチリル基、ラウリル基、ベンゾイル基で修飾したセルロース微細繊維は、トルエンやジクロロメタンにも分散可能である。 Cellulose microfibers made according to the present invention are readily dispersible in organic solvents. The organic solvent in which cellulose fine fibers can be dispersed depends on the type of acyl group. For example, cellulose fine fibers modified with aliphatic acyl groups having 2 to 3 carbon atoms can be dispersed in alcohols, amides and polar organic solvents such as tetrahydrofuran. On the other hand, cellulose fine fibers modified with an aliphatic acyl group having 4 or more carbon atoms or an aromatic acyl group can be dispersed in both polar and hydrophobic solvents. For example, cellulose microfibers modified with butyryl, lauryl, and benzoyl groups are also dispersible in toluene and dichloromethane.
以下に、実施例に基づいて本発明をより詳細に説明するが、本発明はこれらの実施例によって限定されるものではない。なお、用いた原料の詳細は以下の通りであり、得られた修飾セルロース微細繊維の特性は以下のようにして測定した。 EXAMPLES The present invention will be described in more detail below based on examples, but the present invention is not limited by these examples. The details of the raw materials used are as follows, and the properties of the obtained modified cellulose fine fibers were measured as follows.
（用いた原料、試薬）
セルロースパルプ：ＮＢＫＰパルプ（キャンフォー）とコットンリンターパルプを用いた。何れも丸紅株式会社から入手した。セルロースパルプをサンプル瓶に入れるサイズまで千切ったパルプ。
４０％水酸化テトラプロピルアンモニウム水溶液：東京化成工業株式会社製。
３５％水酸化テトラエチルアンモニウム水溶液：東京化成工業株式会社製。
４０％水酸化テトラブチルアンモニウム水溶液：東京化成工業株式会社製。
カルボン酸ビニル、ＤＭＳＯ、他の原料：ナカライテスク（株）製の試薬。
(Raw materials and reagents used)
Cellulose pulp: NBKP pulp (Canfor) and cotton linter pulp were used. All were obtained from Marubeni Corporation. Pulp that has been shredded to a size that can be put into a sample bottle.
40% tetrapropylammonium hydroxide aqueous solution: manufactured by Tokyo Chemical Industry Co., Ltd.
35% tetraethylammonium hydroxide aqueous solution: manufactured by Tokyo Chemical Industry Co., Ltd.
40% tetrabutylammonium hydroxide aqueous solution: manufactured by Tokyo Chemical Industry Co., Ltd.
Vinyl carboxylate, DMSO, other raw materials: Reagents manufactured by Nacalai Tesque.
（アシル化修飾セルロース微細繊維のＩＲスペクトル）
セルロース微細繊維のＩＲスペクトルはフーリエ変換赤外分光光度計（ＦＴ－ＩＲ）で測定した。なお、測定は、ＮＩＣＯＬＥＴ社製「ＮＩＣＯＬＥＴ ＭＡＧＮＡ－ＩＲ７６０ Ｓｐｅｃｔｒｏｍｅｔｅｒ」を用い、反射モードで分析した。アシル化修飾は周波数１７３０ｃｍ－１の吸収バンドにより確認した。
(IR spectrum of acylated modified cellulose fine fiber)
IR spectra of cellulose microfibers were measured with a Fourier transform infrared spectrophotometer (FT-IR). The measurement was performed in reflection mode using a "NICOLET MAGNA-IR760 Spectrometer" manufactured by NICOLET. Acylation modification was confirmed by an absorption band at a frequency of 1730 cm −1 .
（アシル化修飾セルロース微細繊維の平均置換度の評価）
規定量のアシル化修飾セルロース微細繊維をＮａＯＨ／ＥｔＯＨ／Ｈ２Ｏの混合液に分散させ、室温で４時間撹拌することによりエステル結合が加水分解し、アシル基がＣＮＦの水酸基から外れ、アシル化ＣＮＦが無修飾ＣＮＦに変換される。一方、外れたアシル基は水酸化ナトリウムと結合してカルボン酸ナトリウムに変換し、そのモル数は下に示す滴定法により定量できる。
加水分解後、反応溶液（溶媒、カルボン酸ナトリウムと水酸化ナトリウム）と残渣（無修飾ＣＮＦ）をろ過により分離した。残渣を乾燥し、天秤で秤量した。溶液を塩酸水溶液で滴定することにより水酸化ナトリウムの残留量を定量した。
加水分解溶液に加えた水酸化ナトリウムの当量数をＡ、加水分解後回収、乾燥後ＣＮＦの重さをＷ、滴定に消耗された塩酸の当量数をＢとして、下式によりアシル基のモル数（Ｃ）とアシル基の平均置換度ＤＳを算出した。
セルロース（無水グルカン）のモル数（Ｍ）＝Ｗ／１６２
アシル基のモル数Ｃ＝Ａ－Ｂ
平均置換度ＤＳ＝Ｃ／Ｍ
(Evaluation of Average Degree of Substitution of Acylated Modified Cellulose Fine Fibers)
A specified amount of acylated modified cellulose fine fibers is dispersed in a mixture of NaOH/EtOH/H 2 O and stirred at room temperature for 4 hours to hydrolyze the ester bond, remove the acyl group from the hydroxyl group of CNF, and acylate. CNF is converted to unmodified CNF. On the other hand, the detached acyl group is combined with sodium hydroxide to convert to sodium carboxylate, and the number of moles thereof can be quantified by the titration method shown below.
After hydrolysis, the reaction solution (solvent, sodium carboxylate and sodium hydroxide) and the residue (unmodified CNF) were separated by filtration. The residue was dried and weighed on a balance. The residual amount of sodium hydroxide was quantified by titrating the solution with aqueous hydrochloric acid.
The number of equivalents of sodium hydroxide added to the hydrolysis solution is A, the weight of CNF recovered after hydrolysis and after drying is W, and the number of equivalents of hydrochloric acid consumed for titration is B, the number of moles of acyl groups is calculated by the following formula. The average degree of substitution DS between (C) and the acyl group was calculated.
Number of moles (M) of cellulose (anhydrous glucan) = W/162
Number of moles of acyl group C = AB
Average degree of substitution DS = C/M
（ＳＥＭ観察）
セルロース微細繊維の形状はＦＥ－ＳＥＭ（日本電子（株）製「ＪＳＭ－６７００Ｆ」、測定条件：２０ｍＡ、６０秒）を用いて観察した。
(SEM observation)
The shape of the cellulose fine fibers was observed using an FE-SEM (“JSM-6700F” manufactured by JEOL Ltd., measurement conditions: 20 mA, 60 seconds).
（アシル化修飾セルロース微細繊維の有機溶媒分散性の評価）
アシル化修飾セルロース微細繊維の有機溶媒への分散性は、アシル化修飾率と解繊度合を反映するパラメターである。本発明は以下の方法により評価する。
洗浄したアシル化修飾セルロース微細繊維（乾燥重量０．０５ｇ）と分散用溶媒１０ｇをそれぞれ２０ｍｌのサンプル瓶に入れ、スターラーでよく撹拌した後、室温で６時間静置した後観察し、沈殿しない場合は分散良好と判断した。一方、沈殿し場合は分散不可と評価した。
(Evaluation of organic solvent dispersibility of acylated modified cellulose fine fibers)
The dispersibility of the acylated cellulose fine fibers in an organic solvent is a parameter that reflects the acylation modification rate and the defibration degree. The present invention is evaluated by the following methods.
Put the washed acylated modified cellulose fine fibers (dry weight 0.05 g) and 10 g of the dispersion solvent in a 20 ml sample bottle, stir well with a stirrer, leave at room temperature for 6 hours, and observe. was judged to have good dispersion. On the other hand, when it precipitated, it was evaluated as not dispersible.
（アシル化修飾セルロース微細繊維の結晶化度の評価）
アシル化修飾セルロース微細繊維の分散液を乾燥し、粉末Ｘ線結晶回折（ＸＲＤ）を用いて結晶化度を測定した。なお、Ｘ線回折装置（ＵｌｔｉｍａＩＶ、株式会社リガク製）を使用して分析した。測定条件を次に示した。
・Ｘ線：Ｃｕ／４０ｋＶ／４０ｍＡ
・スキャンスピード：１０°／分
・走査範囲：２θ＝５～７０°
また、下記式によって、結晶化度を算出した（Ｔｅｘｔｉｌｅ Ｒｅｓ．Ｊ．２９：７８６－７９４，１９５９参照）。
結晶化度（％）＝［（Ｉ２００－ＩＡＭ）／Ｉ２００］×１００
Ｉ２００：２θ＝２２．６°の回折強度
ＩＡＭ：アモルファス部の回折強度であり２θ＝１８．５°の回折強度
(Evaluation of crystallinity of acylated modified cellulose fine fibers)
The dispersion of acylated modified cellulose microfibers was dried and crystallinity was measured using powder X-ray crystal diffraction (XRD). The analysis was performed using an X-ray diffractometer (Ultima IV, manufactured by Rigaku Corporation). The measurement conditions are shown below.
・X-ray: Cu/40kV/40mA
・Scan speed: 10°/min ・Scan range: 2θ = 5 to 70°
Also, the degree of crystallinity was calculated by the following formula (see Textile Res. J. 29:786-794, 1959).
Crystallinity (%) = [(I200-IAM) / I200] × 100
I200: Diffraction intensity at 2θ=22.6° IAM: Diffraction intensity at 2θ=18.5°, which is the diffraction intensity of the amorphous portion
〔実施例１〕
４０％の水酸化テトラプロピルアンモニウム（ＴＰＡＨ）水溶液０．１ｇ、ジメチルスルホキシド５ｇを１０ｍｌのサンプル瓶に入れ、２３℃磁性スターラーで混合液が均一に混ざるまで攪拌した。次に、コトンリンターパルプ０．２３ｇを加え１時間攪拌した後、酢酸ビニル０．２５ｇを入れて１時間攪拌することでアセチル化修飾した。次に、蒸留水で洗浄することにより修飾反応溶液（ＴＰＡＨ、酢酸ビニルとＤＭＳＯ）と副生物（アセトアルデヒド）を除いた。得られたセルロース微細繊維について、修飾有無をＦＴ－ＩＲ分析で確認した結果、ＩＲスペクトル（図１）は周波数１７３０ｃｍ－１付近に強い吸収バンドが検出された。また、平均置換度と結晶化度を評価した結果、それぞれは１．３と６８％であった（表１）。ＳＥＭで形状を観察した結果を図２に示した。殆どのセルロース微細繊維の繊維径は数１０～数１００ｎｍ、長さは数μｍ～数十μｍに分布している。アセチル化微細繊維をエタノール、イソプロパノール、テトラヒドロフラン、ジクロロメタン等の溶媒に分散し、得られた分散液は室温で静置しても沈降による層分離が見られなかった。
[Example 1]
0.1 g of a 40% tetrapropylammonium hydroxide (TPAH) aqueous solution and 5 g of dimethyl sulfoxide were placed in a 10 ml sample bottle and stirred with a magnetic stirrer at 23° C. until the mixture was uniformly mixed. Next, 0.23 g of cotton linter pulp was added and stirred for 1 hour, and then 0.25 g of vinyl acetate was added and stirred for 1 hour for acetylation modification. Modification reaction solutions (TPAH, vinyl acetate and DMSO) and by-products (acetaldehyde) were then removed by washing with distilled water. As a result of confirming the presence or absence of modification of the obtained cellulose fine fibers by FT-IR analysis, a strong absorption band was detected near a frequency of 1730 cm −1 in the IR spectrum (FIG. 1). Moreover, as a result of evaluating the average degree of substitution and the degree of crystallinity, they were 1.3 and 68%, respectively (Table 1). FIG. 2 shows the result of observing the shape with SEM. Most of the cellulose fine fibers have a fiber diameter of several tens to several hundred nm and a length of several micrometers to several tens of micrometers. The acetylated fine fibers were dispersed in solvents such as ethanol, isopropanol, tetrahydrofuran, and dichloromethane, and the obtained dispersion did not show layer separation due to sedimentation even when left standing at room temperature.
〔実施例２〕
４０％ＴＰＡＨ水溶液と酢酸ビニルの添加量をそれぞれ０．０６ｇと０．１５ｇにした以外は実施例１と同様に実施と評価した。結果を図１（ＩＲスペクトル）、図３（ＳＥＭ写真）と表１（平均置換度と結晶化度）にそれぞれ示した。ＴＰＡＨ水溶液と酢酸ビニルの添加量を減らすことで修飾率は低下したが、解繊度合は殆ど変わらなかった。ＳＥＭで形状を観察した結果、殆どのセルロース微細繊維の繊維径は数１０～数１００ｎｍ、長さは数μｍ～数十μｍに分布している。アセチル化微細繊維をエタノール、イソプロパノール、テトラヒドロフラン、ジクロロメタン等の溶媒に分散し、得られた分散液は室温で静置しても沈降による層分離が見られなかった。
[Example 2]
Evaluation was carried out in the same manner as in Example 1 except that the amounts of the 40% TPAH aqueous solution and vinyl acetate added were changed to 0.06 g and 0.15 g, respectively. The results are shown in FIG. 1 (IR spectrum), FIG. 3 (SEM photograph) and Table 1 (average degree of substitution and crystallinity), respectively. By reducing the amounts of the TPAH aqueous solution and vinyl acetate added, the modification rate decreased, but the defibration degree remained almost unchanged. As a result of observing the shape with an SEM, most of the cellulose fine fibers have a fiber diameter of several tens to several hundred nm and a length of several μm to several tens of μm. The acetylated fine fibers were dispersed in solvents such as ethanol, isopropanol, tetrahydrofuran, and dichloromethane, and the obtained dispersion did not show layer separation due to sedimentation even when left standing at room temperature.
〔実施例３〕
反応温度を５５℃にした以外は実施例２と同様にして実施し評価した。結果を図４と表１に示した。結晶化度は実施例２とほぼ同等であったが、平均置換度は実施例２を上回った。ＳＥＭで形状を観察した結果、一部の粗大繊維が観察されたが、殆どのセルロース微細繊維の繊維径は数１０～数１００ｎｍ、長さは数μｍ～数十μｍに分布している。アセチル化微細繊維をエタノール、イソプロパノール、テトラヒドロフラン、ジクロロメタン等の溶媒に分散し、得られた分散液は室温で静置しても沈降による層分離が見られなかった。
[Example 3]
Evaluation was carried out in the same manner as in Example 2 except that the reaction temperature was changed to 55°C. The results are shown in FIG. 4 and Table 1. The degree of crystallinity was almost the same as in Example 2, but the average degree of substitution exceeded that in Example 2. As a result of observing the shape with an SEM, some coarse fibers were observed, but most of the cellulose fine fibers were distributed with a fiber diameter of several tens to several hundred nm and a length of several μm to several tens of μm. The acetylated fine fibers were dispersed in solvents such as ethanol, isopropanol, tetrahydrofuran, and dichloromethane, and the obtained dispersion did not show layer separation due to sedimentation even when left standing at room temperature.
〔実施例４〕
４０％ＴＰＡＨ水溶液に代えて４０％のＴＢＡＨ水溶液を用いた以外は実施例２と同様に実施と評価した。結果を図１（ＩＲスペクトル）、図４（ＳＥＭ写真）と表１（平均置換度と結晶化度）にそれぞれ示した。ＳＥＭで形状を観察した結果、一部の粗大繊維が観察されたが、殆どのセルロース微細繊維の繊維径は数１０～数１００ｎｍ、長さは数μｍ～数十μｍに分布している。アセチル化微細繊維をエタノール、イソプロパノール、テトラヒドロフラン、ジクロロメタン等の溶媒に分散し、得られた分散液は室温で静置しても沈降による層分離が見られなかった。ＴＢＡＨはＴＰＡＨとほぼ同等な解繊促進効果を有することが分かった。
[Example 4]
Evaluation was carried out in the same manner as in Example 2 except that a 40% TBAH aqueous solution was used instead of the 40% TPAH aqueous solution. The results are shown in FIG. 1 (IR spectrum), FIG. 4 (SEM photograph) and Table 1 (average degree of substitution and crystallinity), respectively. As a result of observing the shape with an SEM, some coarse fibers were observed, but most of the cellulose fine fibers were distributed with a fiber diameter of several tens to several hundred nm and a length of several μm to several tens of μm. The acetylated fine fibers were dispersed in solvents such as ethanol, isopropanol, tetrahydrofuran, and dichloromethane, and the obtained dispersion did not show layer separation due to sedimentation even when left standing at room temperature. It was found that TBAH has almost the same fibrillation promoting effect as TPAH.
〔実施例５〕
４０％ＴＰＡＨ水溶液に代えて４０％のＴＥＡＨ水溶液を用いた以外は実施例２と同様に実施と評価した。結果を図５（ＳＥＭ写真）と表１（平均置換度と結晶化度）にそれぞれ示した。結晶化度は実施例２とほぼ同等であった。平均置換度は実施例２より高かったが、粗大繊維の含有量が増えた。ＴＰＡＨと比べ解繊の促進作用がやや低下したが、有機溶媒への分散性は殆ど変わらなかった。
[Example 5]
Evaluation was carried out in the same manner as in Example 2, except that a 40% TEAH aqueous solution was used instead of the 40% TPAH aqueous solution. The results are shown in FIG. 5 (SEM photograph) and Table 1 (average degree of substitution and degree of crystallinity), respectively. The degree of crystallinity was almost the same as in Example 2. The average degree of substitution was higher than in Example 2, but the content of coarse fibers was increased. Compared to TPAH, the fibrillation promoting action was slightly reduced, but the dispersibility in organic solvents was almost unchanged.
〔実施例６〕
コトンリンターパルプに代えてキャンフォーパルプを用いた以外は実施例２と同様に実施と評価した。結果を図１（ＩＲスペクトル）、図６（ＳＥＭ写真）と表１（平均置換度と結晶化度）にそれぞれ示した。評価結果から、セルロースの原料を変えても同等な修飾と解繊度合が得られることが判明した。
[Example 6]
Evaluation was carried out in the same manner as in Example 2, except that canfor pulp was used instead of cotton linter pulp. The results are shown in FIG. 1 (IR spectrum), FIG. 6 (SEM photograph) and Table 1 (average degree of substitution and crystallinity), respectively. From the evaluation results, it was found that even if the raw material of cellulose is changed, the same degree of modification and fibrillation can be obtained.
〔実施例７〕
予備膨潤／解繊せず、最初から酢酸ビニルを添加し２時間攪拌した以外実施例１と同様にアセチル化修飾セルロース微細繊維を調製し評価した。得られたセルロース微細繊維の平均置換度は１．３１、結晶化度は６５％（表１）であった。ＩＲスペクトルを図１，ＳＥＭ写真を図７に示した。ＳＥＭ観察の結果から、粗大繊維は実施例１より多かったが、微細繊維のほうは実施例とほぼ同等な形状とサイズを持つことが判明した。
[Example 7]
Acetylation-modified cellulose fine fibers were prepared and evaluated in the same manner as in Example 1 except that vinyl acetate was added from the beginning and stirred for 2 hours without pre-swelling/fibrillation. The obtained cellulose fine fibers had an average degree of substitution of 1.31 and a degree of crystallinity of 65% (Table 1). The IR spectrum is shown in FIG. 1, and the SEM photograph is shown in FIG. From the results of SEM observation, it was found that the coarse fibers were larger than those of Example 1, but the fine fibers had substantially the same shape and size as those of Examples.
〔比較例１〕
水酸化テトラプロピルアンモニウム水溶液を添加しない以外は実施例６と同様にしてセルロースのアシル化修飾反応を行った。実施例１と同様に洗浄し固形分を回収した。回収した固形分のＳＥＭ写真を図８に示す。原料のパルプ繊維とほぼ同様な粗大繊維が観察された。ＦＴ－ＩＲ分析の結果（図１）により修飾は殆どなかった。
[Comparative Example 1]
The acylation modification reaction of cellulose was carried out in the same manner as in Example 6, except that the tetrapropylammonium hydroxide aqueous solution was not added. It was washed in the same manner as in Example 1 and the solid content was recovered. A SEM photograph of the collected solid content is shown in FIG. Coarse fibers similar to those of raw material pulp fibers were observed. The FT-IR analysis results (Fig. 1) showed little modification.
〔比較例２〕
４０％の水酸化テトラプロピルアンモニウム（ＴＰＡＨ）水溶液の添加量を０．１８ｇに変更した以外は実施例１と同様にしてセルロースのアシル化修飾反応を行った。実施例１と同様に洗浄し固形分を回収した。回収したアセチル化セルロース微細繊維の平均置換度は１．１３であり、結晶化度は４５％まで低下した。この結果から、一部のセルロースは完全溶解し酢酸セルロースに変換されたと考える。
[Comparative Example 2]
The acylation modification reaction of cellulose was carried out in the same manner as in Example 1, except that the amount of 40% tetrapropylammonium hydroxide (TPAH) aqueous solution added was changed to 0.18 g. It was washed in the same manner as in Example 1 and the solid content was recovered. The recovered acetylated cellulose fine fibers had an average degree of substitution of 1.13 and a crystallinity of 45%. From this result, it is considered that part of the cellulose was completely dissolved and converted to cellulose acetate.
実施例１～７及び比較例１、２の修飾反応溶液の組成と反応条件及び得られたセルロース微細繊維の平均置換度、結晶化度をまとめて表１に示す。
本発明の修飾セルロース微細繊維は、各種複合材料、コーティング剤に利用でき、シートやフィルムに成形して利用することもできる。
The modified cellulose fine fibers of the present invention can be used for various composite materials and coating agents, and can also be used by molding into sheets and films.
Claims (3)
Ｒ４Ｎ＋ＯＨ－ （１）
（式中、Ｒはそれぞれ独立して炭素数が２～４のアルキル基を表す）。 Acylation-modified cellulose comprising permeating cellulose with a modification reaction solution containing a tetraalkylammonium hydroxide represented by the following formula (1), water, dimethylsulfoxide and an acylating agent to acylate and defibrate the cellulose. A method for producing fine fibers.
R 4 N + OH − (1)
(In the formula, each R independently represents an alkyl group having 2 to 4 carbon atoms).
Ｒ４Ｎ＋ＯＨ－ （１）
（式中、Ｒはそれぞれ独立して炭素数が２～４のアルキル基を表す）。 A solution containing a tetraalkylammonium hydroxide represented by the following formula (1), water, and dimethylsulfoxide is permeated into cellulose to swell and/or partially defiberize the cellulose, and then an acylating agent is added to the solution for modification. A method for producing acylated cellulose fine fibers, which comprises acylating and defibrating the swollen and/or partially defiberized cellulose as a reaction solution.
R 4 N + OH − (1)
(In the formula, each R independently represents an alkyl group having 2 to 4 carbon atoms).
The component ratio of tetraalkylammonium hydroxide, water, methylsulfoxide and acylating agent in the modification reaction solution is such that the total amount of tetraalkylammonium hydroxide, water, methylsulfoxide and acylating agent is is 0.1 to 1.2 wt%, water is 0.1 to 1.8 wt%, dimethyl sulfoxide is 82.0 to 98.8 wt%, and the acylating agent is 1.0 to 15.0 wt%. The manufacturing method according to claim 1 or claim 2.
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