本發明之含有纖維素纖維之薄片，為具有抗病毒性之單層結構或多層結構的薄片。具體而言，本發明之抗病毒性薄片，基於JIS L 1922：2016(纖維製品之抗病毒性試驗方法)所測定之對流行性感冒病毒或貓杯狀病毒之抗病毒活性值(Mv)為2.0以上，抗病毒活性值更佳為2.5以上或3.0以上。
本發明之抗病毒性薄片，除了抗病毒性以外，亦可具有其他1種以上之機能。本發明之抗病毒性薄片所具有的機能之例子，例如可列舉消臭、抗菌、耐熱、耐濕、耐候、耐溶劑、耐磨耗、電磁波阻斷等，本發明之較佳態樣中，抗病毒性薄片，具有消臭及/或抗菌機能。
本發明之抗病毒性薄片之用途無特別限定，可用於以抗病毒機能為必要之任意用途。抗病毒性薄片之用途，例如可列舉包裝材料(紙器、紙箱、樹脂薄膜、包裝紙等)、建材(壁紙、裝飾紙、襯墊紙等)、衛生用品(尿布、生理用品、擦拭布、口罩、小毛巾、紗布、綿棒等)、生活用品(除臭材、芳香材、食品用濾器、空氣過濾片、餐墊、托架防著板、桌布、排水網、廚房紙巾、烘焙紙、浮沫吸取片、廚房抹布、布巾、圍裙、防熱鍋夾、馬桶座墊紙、廁所地板用飛散防止薄片、浴室腳踏墊、濕紙巾、拋棄式拖鞋、地毯基材、鞋墊、西裝防塵套、手提袋、結露薄片、書套、吸塵器紙袋、紙條、書籤、筆記本、筆記本套、寵物墊、拋棄式墊、枕頭套、被套、擦拭片等)、工業用品(工業用濾器、工業用擦拭布、汽車內裝材等)、醫療品(口罩、防護服、手術服(手術帽/護裙/上衣褲子)、抗菌墊、清潔擦拭用布、醫療用膠帶等)、衣物(免洗內褲等)、園藝/農業用資材(園藝用片材、農業用片材、苗床用片材、果實袋等)、頭靠用罩(高鐵或汽車)、其他紙製品(月曆等)等。
本發明之抗病毒性薄片可為單層結構亦可為多層結構，為多層結構時，必須至少1層以上含有纖維素纖維。又，較佳為載持後述金屬離子及/或金屬粒子之纖維素纖維含於最外層。
本發明之抗病毒性薄片，含有纖維素纖維，纖維素纖維，較佳表面具有陰離子基，且含有選自Ag、Au、Pt、Pd、Ni、Mn、Fe、Ti、Al、Zn及Cu之元素群的1種以上之金屬離子及/或金屬粒子。陰離子基較佳為羧基或羧酸酯基，金屬離子較佳為經離子鍵結。本發明中，較佳具有至少1層的含有載持金屬離子及/或金屬粒子之纖維素纖維(以下亦稱為「含金屬之纖維素纖維」)之層。
含金屬之纖維素纖維以外的原料並無特別限定，可使用公知之原料。作為例子，可包含一種以上的未載持金屬離子或金屬粒子之纖維素纖維(以下亦稱為「一般纖維素纖維」)、合成纖維，或樹脂、無機物等之其他材料。本發明之薄片可含有填料。薄片中之填料之含量無特別限制，較佳為不超過薄片重量之20重量%之範圍，亦可為10重量%以下或5重量%以下。填料例如可列舉重質碳酸鈣、輕質碳酸鈣、二氧化矽、矽藻土、氧化鋁、氧化鈦、氧化鎂、輕石粉、輕石球囊(balloon)、氫氧化鋁、氫氧化鎂、鹼性碳酸鎂、白雲石、硫酸鈣、鈦酸鉀、硫酸鋇、亞硫酸鈣、滑石、黏土、雲母、石棉、矽酸鈣、蒙脫石、皂土、石墨、鋁粉、硫化鉬等。
其他材料並無特別限定，例如可依需要使用增積劑、乾燥紙強度提高劑、濕潤紙強度提高劑、濾水性提高劑、良率提高劑、染料、上漿劑、硫酸鋁等。填料以外之其他材料之含量，較佳為合計不超過薄片重量之10重量%。
又，薄片之製造方法並無特別限定，可使用公知之方法。例如，可為將分散有原料之水吐出，藉由壓力或熱而脫水之方法(所謂的濕式)、將原料以乾燥狀態吐出，同樣地藉由壓力或熱而薄片化之方法(所謂的乾式)之任意方法。由於纖維素纖維為親水性，因此較佳藉由濕式來形成薄片。
本發明中，亦可與通常的紙薄片同樣地於紙漿漿料(紙料)混合上述纖維素纖維，並使用該試樣進行抄紙，藉以製造薄片。抄紙可使用長網抄紙機、夾網抄紙機、圓網式抄紙機等公知之抄紙機，其抄紙條件亦無限定。
又，本發明之抗病毒性薄片，亦可依需要進行軋光處理等公知之表面處理。表面處理可使用公知之處理裝置，其條件亦無限定。
本發明之抗病毒性薄片，亦可依需要將不含有顏料之塗覆層(透明塗覆層)設置於薄片之表面。本發明之薄片，較佳於薄片之單面或兩面具備透明塗覆層、更佳具有至少含有澱粉類之透明塗覆層為佳。藉由具有透明塗覆層，本發明之薄片為紙時，可得到特別是平滑性或表面強度、印刷妥適性優良之紙。又，理由雖不明確，但本發明之薄片，即使薄片表面被透明塗覆層被覆，亦具有優良抗病毒活性。
透明塗覆層之塗覆量，每個單面以固體成分計，較佳為0.01~3.0g/m
2、更佳為0.1~2.0g/m
2。透明塗覆，例如可藉由使用上膠壓製、水平輥式塗佈機(gate roll coater)、預計量上膠壓製(premetering size press)、淋幕塗佈機、噴霧塗佈機等之塗佈機(塗覆機)，將塗佈液塗佈於薄片上而形成。透明塗覆液之固體成分濃度，就塗液飛散(boiling)或塗覆量調整之觀點，較佳為2~14重量%，固體成分濃度5重量%時之B型黏度(30℃、60rpm)較佳為5~450mPa･s、更佳為10~300mPa･s。
本發明中，澱粉係指包含直鏈澱粉、支鏈澱粉之混合物，一般而言，其混合比係依澱粉之原材料的植物而異。本發明中澱粉類亦包含來自澱粉之高分子化合物。該高分子，可列舉將澱粉進行變性、修飾、加工等者。作為澱粉類，例如較佳包含生澱粉、氧化澱粉、酯化澱粉、陽離子化澱粉、以經乙醯基化之木薯澱粉為原料而於製紙工廠內藉由熱化學變性或酵素變性所生成的自製變性澱粉等之澱粉、醛化澱粉、羥基乙基化澱粉等之變性澱粉。本發明之透明塗覆層，例如亦可使用羧基甲基纖維素、羥基乙基纖維素、甲基纖維素等之纖維素衍生物、聚丙烯醯胺、聚乙烯醇、羧基變性聚乙烯醇、乙醯乙醯基化聚乙烯醇等之變性醇、苯乙烯-丁二烯系共聚物、聚乙酸乙烯酯、氯乙烯-乙酸乙烯酯系共聚物、聚氯乙烯、聚偏二氯乙烯、聚丙烯酸酯等，亦可併用2種或3種以上。又，以提高上漿性為目的，亦可併用苯乙烯系上漿劑、烯烴系上漿劑、丙烯酸酯系上漿劑、苯乙烯-丙烯酸系上漿劑、陽離子性上漿劑等之表面上漿劑。又，本發明中，係依需要適當使用分散劑、增黏劑、保水材、消泡劑、耐水化劑、著色劑、導電劑等摻合於通常的透明塗膜之各種助劑。
本發明之抗病毒性薄片之每平方公尺的重量並無特別限定，可依需要設定一般的範圍，較佳為10~1000g/m
2之範圍、更佳為10~300g/m
2之範圍、亦可為15~200g/m
2或20~90g/m
2之範圍。每平方公尺的重量大於1000g/m
2時，係有薄片特有之容易彎曲性或容易切斷性不佳，成為問題的情況。薄片為多層結構時，各層之每平方公尺的重量為10g/m
2以上時，就製造均勻且製造時之操作中具備最低限之強度的薄片之觀點而言較佳。
抗病毒性薄片之厚度較佳為20~500μm之範圍、更佳為30~200μm之範圍。薄片為多層結構時，各層之厚度為20μm以上，就製造均勻的薄片之觀點而言較佳。關於薄片之密度並無特別限定。
本發明之抗病毒性薄片具有多層結構時，可將各層每次製造一層之後，以公知方法將該等層合、亦可一邊依次層合各層一邊形成。又，亦能夠以一邊將各層之原料同時吐出一邊一次形成多層的所謂同時多層式來製造薄片。接著各層的方法無特別限制，可使用公知之方法。例如可列舉使用接著劑之方法、藉由通過熱輥之間或吹送熱風來使層彼此融合的方法等。
本發明之抗病毒性薄片為多層結構時，最外層可經一層以上疊層處理，又，亦可如所謂黏著標籤薄片般，於最外層具有用以與其他基材接著之接著層。又，可為將單層之薄片單純地層合者、亦可如紙箱般，1個以上之層具有立體結構者。
本發明之抗病毒性薄片，亦可依需要於最外層進行印刷。
本發明之抗病毒性薄片，含有載持金屬離子及/或金屬粒子之纖維素纖維時，薄片每1g較佳含有金屬離子及金屬粒子合計0.20mg/g以上、更佳為0.25mg/g以上、又更佳為0.30mg/g以上、最佳為0.60mg/g以上。又，薄片每1g較佳含有金屬離子及金屬粒子合計6.3mg/g以下，亦可為5.0mg/g以下或4.0mg/g以下。
藉由使薄片每1g之薄片中之金屬離子及/或金屬粒子之含量合計成為0.20mg/g以上6.3mg/g，容易得到抗病毒機能等優良的薄片，並且可抑制過剩之金屬離子及/或金屬粒子所致之環境負荷增大或薄片著色等。
抗病毒性薄片中之金屬離子及金屬粒子之含量，例如可藉由ICP發光分光分析(ICP-OES)而測定(定量)。
又，含金屬之纖維素纖維之含量，相對於抗病毒性薄片而言較佳為0.5重量%以上。含金屬之纖維素纖維之含量過少時，有無法賦予充分之抗病毒機能的情況。上述含量之上限值並無特別限定，可依所要求之抗病毒、消臭、抗菌機能等之程度而適當調整，亦可為100重量%。含金屬之纖維素纖維之含量，例如亦可為1~80重量%、2~60重量%、3~40重量%等。
又，如上所述，含金屬之纖維素纖維之含量相對於抗病毒性薄片而言較佳為0.5重量%以上，故抗病毒性薄片中之一般纖維素纖維之含量較佳為99.5重量%以下。一般纖維素纖維之含量之下限值並無特別限定，亦可不含一般纖維素纖維。
本發明之抗病毒性薄片含有纖維素纖維而成。本發明中之纖維素纖維之種類無特別限定，可依需要使用任意種類者。又，能夠以任意比率混合來使用該等之中2種以上之纖維素纖維。纖維素纖維之來源無特別限制，可列舉來自植物、來自動物、來自藻類、來自微生物等之纖維素纖維為例，其中尤以來自植物或來自微生物之纖維素纖維為佳、特佳為來自植物之纖維素纖維。
來自植物之纖維素纖維，例如可列舉木材、竹、麻、黃麻、洋麻、農地殘餘廢料、紙漿(針葉樹未漂白牛皮紙漿(NUKP)、針葉樹漂白牛皮紙漿(NBKP)、闊葉樹未漂白牛皮紙漿(LUKP)、闊葉樹漂白牛皮紙漿(LBKP)、針葉樹未漂白亞硫酸鹽紙漿(NUSP)、針葉樹漂白亞硫酸鹽紙漿(NBSP)、熱磨機械紙漿(TMP)、再生紙漿、回收紙漿等)，來自動物之纖維素纖維，例如可列舉來自海鞘類之纖維素纖維，來自微生物之纖維素纖維，例如可列舉來自乙酸菌(醋酸菌)之纖維素纖維。
本發明之薄片為紙時，較佳含有LBKP及/或回收紙漿作為纖維素纖維。LBKP或回收紙漿，其纖維長較短，藉由含有此等紙漿，可得到平滑性優良的紙，如此所得之紙，其表面性或印刷妥適性(特別是印刷面感)優良。
本發明所用之纖維素原料之數平均纖維直徑及數平均纖維長並無特別限制，可依需要使用任意之數平均纖維直徑及數平均纖維長者。又，能夠以任意比率混合使用數平均纖維直徑及數平均纖維長不同的2種以上之纖維素纖維。作為例子，一般的紙漿之一的針葉樹牛皮紙漿(NBKP)的情況時，數平均纖維直徑為30~60μm左右、數平均纖維長為3~5mm左右，闊葉樹漂白牛皮紙漿(LBKP)的情況時，數平均纖維直徑為10~30μm左右、數平均纖維長為1~2mm左右。
(1)纖維素纖維之變性
纖維素纖維，每個葡萄糖單位具有3個羥基，可進行各種化學變性處理。本發明中，較佳於處理後進行具有陰離子基之化學變性處理。
導入有陰離子基之纖維素纖維，例如可列舉具有羧基或羧酸酯基之氧化纖維素纖維、具有磷酸基之磷酸酯化纖維素纖維、具有亞磷酸基之亞磷酸酯化纖維素纖維、具有硫酸基之磺化纖維素纖維等。本發明中，為了於後述步驟中對纖維素纖維之至少一部分導入金屬離子或金屬粒子，較佳進行對纖維素纖維之至少一部分導入羧基或羧酸酯基之變性(氧化)。再者，本說明書中，亦有將導入纖維素纖維之陰離子基稱為酸基者。
此處，羧基係指-COOH表示之基，羧酸酯基係指-COO-表示之基。羧酸酯基之相對離子並無特別限定。如後述般金屬粒子係透過與羧酸酯基之離子鍵而形成時，該金屬離子係為相對離子。
具有陰離子基(酸基)之纖維素纖維之陰離子基量，作為一例可藉由以下方法測定。
調製具有陰離子基(酸基)之纖維素纖維試樣之0.5質量%漿料(水分散液)60ml，添加0.1M鹽酸水溶液使成為pH2.5後，滴下0.05N之氫氧化鈉水溶液，測定導電度至pH成為11，測定於導電度之變化和緩的弱酸之中和階段所消耗之氫氧化鈉量(a)。接著，使用下式算出具有陰離子基(酸基)之纖維素纖維之陰離子基量[mmol/g]。式中，x為相當於酸基價數之值，羧基、羧酸酯基、亞磷酸基、磺酸基的情況時為1、磷酸基的情況時為2。
a[ml]×0.05/具有陰離子基(酸基)之纖維素纖維之重量[g]/x
又，具有羧基烷基之羧基烷基化纖維素纖維中，以羧基烷基化處理將陰離子基之量予以定量時，可使用以下手法。
(1) 精秤羧基甲基化纖維素(絕對乾重)約2.0g，置入300mL容積附瓶塞的三角燒瓶中。
(2) 添加於甲醇1000mL中加入特級濃硝酸100mL所得的硝酸甲醇溶液100mL，振盪3小時，使羧基甲基纖維素鹽(羧基甲基化纖維素)成為氫型羧基甲基化纖維素。
(3) 精秤氫型羧基甲基化纖維素(絕對乾重)1.5~2.0g，置入300mL容積附瓶塞的三角燒瓶中。
(4) 以80%甲醇15mL使氫型羧基甲基化纖維素濕潤，添加0.1N之NaOH 100mL，於室溫振盪3小時。
(5) 使用酚酞作為指示藥，以0.1N之H
2SO
4將過剩之NaOH進行逆滴定。
(6) 藉由下式算出羧基烷基取代度(DS)：
A=[(100×F’-(0.1N之H
2SO
4)(mL)×F)×0.1]/(氫型羧基烷基化纖維素之絕對乾重質量(g))
DS=0.162×A/(1-0.058×A)
A：氫型羧基烷基化纖維素1g之中和所需的1N之NaOH量(mL)
F’：0.1N之NaOH之因子
F：0.1N之H
2SO
4之因子
以下，說明於纖維素纖維表面之葡萄糖單位中導入陰離子基之方法。
(1-1)氧化
本發明中，於纖維素纖維中導入羧基或羧酸酯基之變性(氧化)之方法，只要變性後之纖維素纖維含有羧基或羧酸酯基則無特別限定，可使用公知之方法。
作為一例，可列舉於選自由N-氧基化合物，及溴化物、碘化物或此等之混合物所成之群的物質之存在下，使用氧化劑於水中使纖維素原料氧化之方法。依照該方法，纖維素表面之葡萄呲喃糖環之C6位置的一級羥基係選擇性地被氧化，產生選自由醛基、羧基及羧酸酯基所成之群之基。反應時之纖維素原料的濃度並無特別限定，較佳為5重量%以下。
N-氧基化合物，係指可產生硝醯基自由基之化合物。硝醯基自由基例如可列舉2,2,6,6-四甲基哌啶1-氧基(TEMPO)。N-氧基化合物，只要係會促進目的之氧化反應的化合物，則任意化合物均可使用。
N-氧基化合物之使用量，只要係可使纖維素纖維氧化之催化量，則無特別限制。例如，相對於絕對乾重1g之纖維素而言，較佳為0.01mmol以上、更佳為0.02mmol以上。上限較佳為10mmol以下、更佳為1mmol以下、又更佳為0.5mmol以下。因此，N-氧基化合物之使用量，相對於絕對乾重1g之纖維素而言，較佳為0.01~10mmol、更佳為0.01~1mmol、又更佳為0.02~0.5mmol。
溴化物係指含有溴之化合物，例如，可列舉可於水中解離而離子化之溴化鹼金屬例如溴化鈉等。又，碘化物係指含有碘之化合物，例如可列舉碘化鹼金屬。溴化物或碘化物之使用量，只要於可促進氧化反應之範圍選擇即可。溴化物及碘化物之合計量，相對於絕對乾重1g之纖維素而言，較佳為0.1mmol以上、更佳為0.5mmol以上。上限較佳為100mmol以下、更佳為10mmol以下、又更佳為5mmol以下。因此，溴化物及碘化物之合計量，相對於絕對乾重1g之纖維素而言，較佳為0.1~100mmol、更佳為0.1~10mmol、又更佳為0.5~5mmol。
氧化劑並無特別限定，例如可列舉鹵素、次鹵酸、亞鹵酸、過鹵酸、該等之鹽、鹵氧化物、過氧化物等。其中尤其是由於價格便宜且環境負荷少，故較佳為次鹵酸或其鹽、更佳為次氯酸或其鹽、又更佳為次氯酸鈉。
氧化劑之使用量，相對於絕對乾重1g之纖維素而言，較佳為0.5mmol以上、更佳為1mmol以上、又更佳為3mmol以上。上限較佳為500mmol以下、更佳為50mmol以下、又更佳為25mmol以下。因此，氧化劑之使用量，相對於絕對乾重1g之纖維素而言，較佳為0.5~500mmol、更佳為0.5~50mmol、又更佳為1~25mmol、最佳為3~10mmol。
使用N-氧基化合物時，氧化劑之使用量，相對於N-氧基化合物1mol而言，較佳為1mol以上，上限較佳為40mol。因此，氧化劑之使用量，相對於N-氧基化合物1mol而言，較佳為1~40mol。
氧化反應時之pH、溫度等條件並無特別限定，一般而言，即使是比較溫和的條件，氧化反應亦效率良好地進行。反應溫度較佳為4℃以上、更佳為15℃以上。上限較佳為40℃以下、更佳為30℃以下。因此，溫度較佳為4~40℃，亦可為15~30℃左右亦即室溫。
反應液之pH較佳為8以上、更佳為10以上。上限較佳為12以下、更佳為11以下。因此，反應液之pH，較佳為8~12、更佳為10~11左右。
通常，伴隨氧化反應之進行，於纖維素中會生成羧基，因此反應液之pH有降低的傾向。因此，為了使氧化反應效率良好地進行，較佳為添加氫氧化鈉水溶液等之鹼性溶液，將反應液之pH維持在上述之範圍。氧化時之反應介質，就操作性容易性或不易產生副反應等之理由而言，較佳為水。
氧化之反應時間，可遵照氧化進行的程度而適當設定，通常為0.5小時以上。上限通常為6小時以下、較佳為4小時以下。因此，氧化之反應時間通常為0.5~6小時、例如0.5~4小時左右。
氧化亦可分為2階段以上之反應來實施。例如，藉由將第1段之反應結束後濾離所得的氧化纖維素，再度以相同或相異之反應條件氧化，可在不受到第1段之反應所副生成的食鹽阻礙反應之下，效率良好地進行氧化。
導入羧基或羧酸酯基之變性(氧化)的方法之別的例子，可列舉藉由臭氧處理來氧化之方法。藉由該氧化反應，構成纖維素之葡萄呲喃糖環的至少2位及6位之羥基被氧化，並且發生纖維素鏈的分解。
臭氧處理通常係藉由使含有臭氧之氣體與纖維素原料接觸來進行。氣體中之臭氧濃度，較佳為50g/m
3以上。上限較佳為250g/m
3以下、更佳為220g/m
3以下。因此，氣體中之臭氧濃度，較佳為50~250g/m
3、更佳為50~220g/m
3。
臭氧添加量，相對於纖維素原料之固體成分100重量%而言，較佳為0.1質量份以上、更佳為5重量%以上。上限通常為30重量%以下。因此，臭氧添加量，相對於纖維素原料之固體成分100重量%而言，較佳為0.1~30重量%、更佳為5~30重量%。
臭氧處理溫度，通常為0℃以上、較佳為20℃以上。上限通常為50℃以下。因此，臭氧處理溫度，較佳為0~50℃、更佳為20~50℃。臭氧處理時間，通常為1分鐘以上、較佳為30分鐘以上。上限通常為360分鐘以下。因此，臭氧處理時間，通常為1~360分鐘左右、較佳為30~360分鐘左右。臭氧處理之條件若為上述之範圍內，可防止纖維素過度地氧化及分解，氧化纖維素之產率成為良好。
亦可對臭氧處理後所得之結果物進一步使用氧化劑進行追加氧化處理。追氧化處理所用之氧化劑並無特別限定，例如可列舉二氧化氯、亞氯酸鈉等之氯系化合物；氧、過氧化氫、過硫酸、過乙酸等。對氧化處理之方法例如可列舉將此等之氧化劑溶解於水或醇等之極性有機溶劑中製成氧化劑溶液，於氧化劑溶液中浸漬纖維素原料之方法。
具有羧基或羧酸酯基之氧化纖維素纖維之陰離子基量，較佳為0.01~3.0mmol/g、更佳為0.20~2.2mmol/g。陰離子基未達0.01mmol/g時，於後述對纖維素纖維載持金屬離子或金屬粒子之步驟中，纖維素纖維表面所存在的金屬粒子之量不充分，有抗病毒、消臭、抗菌機能不良的情況。另一方面，陰離子基超過3.0mmol/g時，有發生金屬粒子之凝集，抗病毒、消臭、抗菌機能不良的情況，並且氧化反應時容易發生作為副反應之纖維素之切斷，有產率降低的情況。
氧化纖維素纖維中所含有的陰離子基(羧基、羧酸酯基)之量，可藉由控制氧化劑之添加量、反應時間等之氧化條件來調整。
(1-2)醚化
作為醚化，於其後步驟中對纖維素纖維導入金屬離子的方便上，只要係於反應後之官能基中含有羧基或羧酸酯基之方法則任何方法均可，可使用公知之方法。可列舉羧基甲基(醚)化、羧基乙基(醚)化、羧基丙基(醚)化、羧基丁基(醚)化等之羧基烷基醚化，或羧基苯基(醚)化為例。其中作為一例，於以下說明羧基甲基化之方法。
羧基甲基化之方法並無特別限定，可使用公知之方法。例如，可列舉將作為發底原料之纖維素原料予以絲光化，之後醚化之方法。羧基甲基化反應時係使用通用溶劑。溶劑例如可列舉水、醇(例如低級醇)及此等之混合溶劑。低級醇例如可列舉甲醇、乙醇、N-丙醇、異丙醇、N-丁醇、異丁醇、3級丁醇。
混合溶劑中之低級醇之混合比例，通常為60重量%以上或95重量%以下、較佳為60~95重量%。溶劑之量，相對於纖維素原料而言通常為3重量倍。上限並無特別限定，但為20重量倍。因此，溶劑之量較佳為3~20重量倍。
絲光化通常係混合發底原料與絲光化劑來進行。絲光化劑例如可列舉氫氧化鈉、氫氧化鉀等之氫氧化鹼金屬。絲光化劑之使用量，相對於發底原料之無水葡萄糖殘基而言，較佳為0.5倍莫耳以上、更佳為1.0倍莫耳以上、又更佳為1.5倍莫耳以上。上限通常為20倍莫耳以下、較佳為10倍莫耳以下、更佳為5倍莫耳以下，因此，較佳為0.5~20倍莫耳、更佳為1.0~10倍莫耳、又更佳為1.5~5倍莫耳。
絲光化之反應溫度通常為0℃以上、較佳為10℃以上。上限通常為70℃以下、較佳為60℃以下。因此，反應溫度通常為0~70℃、較佳為10~60℃。反應時間通常為15分鐘以上、較佳為30分鐘以上。上限通常為8小時以下、較佳為7小時以下。因此，通常為15分鐘~8小時、較佳為30分鐘~7小時。
醚化反應通常係於絲光化後對反應系統追加羧基甲基化劑來進行。羧基甲基化劑例如可列舉單氯乙酸鈉。羧基甲基化劑之添加量，相對於纖維素原料之葡萄糖殘基而言，通常較佳為0.05倍莫耳以上、更佳為0.5倍莫耳以上、又更佳為0.8倍莫耳以上。上限通常為10.0倍莫耳以下、較佳為5倍莫耳以下、更佳為3倍莫耳以下，因此，較佳為0.05~10.0倍莫耳、更佳為0.5~5倍莫耳、又更佳為0.8~3倍莫耳。
反應溫度通常為30℃以上、較佳為40℃以上，上限通常為90℃以下、較佳為80℃以下。因此反應溫度通常為30~90℃、較佳為40~80℃。反應時間通常為30分鐘以上、較佳為1小時以上。上限通常為10小時以下、較佳為4小時以下。因此反應時間通常為30分鐘~10小時、較佳為1小時~4小時。於羧基甲基化反應之間，亦可依需要攪拌反應液。
藉由羧基甲基化將纖維素原料變性時，所得之羧基甲基化纖維素纖維中之無水葡萄糖每單位的羧基甲基取代度，較佳為0.01以上、更佳為0.05以上、又更佳為0.10以上。上限較佳為0.50以下、更佳為0.40以下、又更佳為0.35以下。因此，羧基甲基取代度較佳為0.01~0.50、更佳為0.05~0.40、又更佳為0.10~0.30。
(1-3)酯化
本發明中，對纖維素纖維導入磷酸基、亞磷酸基之變性(酯化)之方法，係任意之方法均可，可使用公知之方法。
具有磷酸基之磷酸酯化纖維素纖維、具有亞磷酸基之亞磷酸酯化纖維素纖維，為經具有磷酸基、亞磷酸基之化合物酯化而得的纖維素纖維。具有磷酸基、亞磷酸基之化合物，例如可列舉磷酸、多磷酸、亞磷酸、膦酸、多膦酸、此等之酯或鹽。此等之化合物為低成本，且易操作。
具有磷酸基、亞磷酸基之化合物之具體例子，可列舉磷酸、磷酸二氫鈉、磷酸氫二鈉、磷酸三鈉、焦磷酸鈉、偏磷酸鈉、磷酸二氫鉀、磷酸氫二鉀、磷酸三鉀、焦磷酸鉀、偏磷酸鉀、磷酸二氫銨、磷酸氫二銨、磷酸三銨、焦磷酸銨、偏磷酸銨、亞磷酸、亞磷酸氫鈉、亞磷酸氫銨、亞磷酸氫鉀、亞磷酸二氫鈉、亞磷酸鈉、亞磷酸鋰、亞磷酸鉀、亞磷酸鎂、亞磷酸鈣、亞磷酸三乙酯、亞磷酸三苯酯、焦亞磷酸等。
其中因酯化效率高，且工業上應用容易的理由，尤以磷酸、磷酸之鈉鹽、磷酸之鉀鹽、磷酸之銨鹽、亞磷酸、亞磷酸之鈉鹽、亞磷酸之鉀鹽、亞磷酸之銨鹽為佳；更佳為磷酸二氫鈉、磷酸氫二鈉、亞磷酸氫鈉、亞磷酸二氫鈉。具有磷酸基、亞磷酸基之化合物可1種單獨使用、亦可組合2種以上使用。
酯化反應，例如係對纖維素原料，使具有磷酸基、亞磷酸基之化合物反應來進行。使纖維素原料與具有磷酸基、亞磷酸基之化合物反應之方法，例如可列舉於纖維素原料中混合具有磷酸基、亞磷酸基之化合物的粉末或水溶液之方法、於纖維素原料之漿料中添加具有磷酸基、亞磷酸基之化合物的水溶液之方法。
此等之中，由提高反應之均勻性，且酯化效率變高的理由，尤以於纖維素原料或其漿料中混合具有磷酸基、亞磷酸基之化合物的水溶液之方法為佳。具有磷酸基、亞磷酸基之化合物的水溶液之pH，就提高磷酸基、亞磷酸基之導入效率的觀點，較佳為7以下，就抑制水解之觀點，更佳為3~7。
具有磷酸基、亞磷酸基之化合物添加量的下限，相對於纖維素原料100重量份而言，以磷原子換算計，較佳為0.2重量份以上、更佳為1重量份以上。藉由成為該範圍，磷酸酯化纖維素纖維、亞磷酸酯化纖維素纖維之產率容易提高。另一方面，其上限較佳為500重量份以下、更佳為400重量份以下。藉由成為該範圍，可以對應於具有磷酸基、亞磷酸基之化合物的添加量之產率而效率良好地得到。
使纖維素原料與具有磷酸基、亞磷酸基之化合物反應時，亦可進一步添加鹼性化合物於反應系統。添加鹼性化合物於反應系統之方法，例如可列舉添加於纖維素原料之漿料的方法、添加於具有磷酸基、亞磷酸基之化合物的水溶液之方法，或添加於纖維素原料與具有磷酸基、亞磷酸基之化合物之漿料的方法。鹼性化合物並無特別限定，較佳為顯示鹼性之含氮化合物。再者，「顯示鹼性」通常意指於酚酞指示藥之存在下鹼性化合物之水溶液呈現粉紅~紅色，或鹼性化合物之水溶液之pH大於7。
顯示鹼性之含氮化合物，只要發揮本發明之效果則無特別限定。其中尤以具有胺基之化合物為佳。例如可列舉尿素、甲基胺、乙基胺、三甲基胺、三乙基胺、單乙醇胺、二乙醇胺、三乙醇胺、吡啶、乙二胺、六亞甲二胺。此等之中，由低成本且易操作之理由，尤以尿素為佳。
鹼性化合物之添加量較佳為2~1000重量份、更佳為100~700重量份。反應溫度較佳為0~95℃、更佳為30~90℃。反應時間並無特別限定，通常為1~600分鐘左右、較佳為30~480分鐘。反應條件若為此等之任一範圍內，可防止於纖維素中過度導入磷酸基、亞磷酸基而容易溶解，磷酸酯化纖維素纖維、亞磷酸酯化纖維素纖維之產率容易提高。
使具有磷酸基、亞磷酸基之化合物反應於纖維素原料後，通常得到懸浮液。懸浮液係依需要脫水，脫水後較佳進行加熱處理。藉此，可抑制纖維素原料之水解。加熱溫度較佳為100~170℃，加熱處理時含有的期間更佳於130℃以下(又更佳為110℃以下)加熱，去除水後，於100~170℃加熱。
磷酸酯化纖維素纖維、亞磷酸酯化纖維素纖維，於煮沸後，較佳實施以冷水洗淨等之洗淨處理。
磷酸酯化纖維素纖維、亞磷酸酯化纖維素纖維中，磷酸酯化纖維素纖維、亞磷酸酯化纖維素纖維中所含有的陰離子基(磷酸基、亞磷酸基)，較佳為0.1~3.5mmol/g。
(1-4)磺化
磺化纖維素纖維為經具有硫酸基之化合物磺化而得的纖維素纖維。具有硫酸酸基之化合物，例如可列舉硫酸、胺磺酸、氯磺酸、三氧化硫、此等之酯或鹽。此等之化合物為低成本且易操作。
本發明中，較佳使用胺磺酸。胺磺酸相較於硫酸酐或硫酸水溶液等而言，不僅纖維素之溶解性小，且酸性度低，故可保持聚合度。又，對於具有強酸性且高腐蝕性之硫酸酐或硫酸水溶液，操作並無限制，亦未被指定為大氣污染防止法之特定物質，故對環境之負荷小。
胺磺酸之使用量，可考慮對纖維素纖維之陰離子基(硫酸基)之導入量而適當調整。胺磺酸例如相對於纖維素分子中之葡萄糖單位每1莫耳而言，較佳能夠以0.01~50莫耳、更佳能夠以0.1~30莫耳來使用。
(2)金屬離子及/或金屬粒子對纖維素纖維之載持
本發明中，藉由對含有陰離子基特別是羧基或羧酸酯基之纖維素纖維，進一步含有選自Ag、Au、Pt、Pd、Ni、Mn、Fe、Ti、Al、Zn及Cu之群的1種以上之金屬元素的金屬離子及/或金屬粒子，會展現優良的抗病毒、消臭、抗菌機能。其中尤其是藉由使用選自Ag及Cu之群的1種以上之離子，抗病毒、消臭、抗菌機能會更加提高，故較佳。
具有陰離子基之纖維素纖維，由於金屬離子或金屬粒子與纖維素纖維係化學性地鍵結，因此於薄片中含有時，金屬成分不易自薄片脫離，且拉伸強度等之力學特性亦良好，具有性能、強度不降低之特徵。
對上述纖維素纖維載持上述金屬離子之方法並無特別限定，例如，可將預先調製之纖維素纖維之分散液與金屬化合物水溶液混合、亦可將含有纖維素纖維之分散液塗佈於基材上而成為膜，對該膜滴下金屬化合物水溶液而進行含浸。此時，膜可維持固定於基材上、亦可為由基材剝離之狀態。
詳細之機制雖不明，但推測係藉由此等之方法，來自金屬化合物之金屬離子，藉由與已與羧酸酯基等之陰離子基進行離子鍵結的鈉離子進行對離子交換，而形成離子鍵或進行配位，藉以對纖維素纖維附加金屬離子。該對離子交換，可認為係因金屬離子彼此之離子化傾向之差而引起。
此處，金屬化合物水溶液，係指金屬鹽之水溶液。金屬鹽之例子，可列舉錯合物(錯離子)、鹵化物、硝酸鹽、硫酸鹽，及乙酸鹽。
金屬化合物水溶液之濃度並無特別限定，相對於纖維素纖維1g而言，較佳為0.2~2.2mmol、更佳為0.4~1.8mmol。使金屬化合物接觸的時間可適當調整。
使金屬化合物接觸時之溫度並無特別限定，較佳為2~50℃之範圍。又，接觸時之液體的pH並無特別限定，但pH較低時，金屬離子不易鍵結於羧基，因此較佳為7~13之範圍、特佳為pH8~12之範圍。
本發明中，如上所述，係藉由對纖維素纖維導入金屬離子而發揮效果，但有金屬離子之一部分被還原而成為金屬粒子的情況。又，亦可依需要，藉由將鍵結於所得含金屬離子之纖維素纖維的金屬離子之一部分以還原劑等之添加而還原，而於纖維素纖維之表面上部分地形成金屬粒子。惟，不進行特別的還原處理，將金屬化合物之總量直接以金屬離子的形態使用，就抗病毒、抗菌、消臭機能之觀點較佳。
藉由將上述所得的含金屬之纖維素纖維中之金屬化合物還原而使金屬粒子於纖維素纖維中生成的機制雖未明朗，但係如以下般推測。藉由還原反應，含金屬化合物之纖維素纖維中的金屬化合物或來自金屬化合物之離子係被還原而成為金屬。此時，所生成之金屬，被載持於纖維素纖維之表面。同樣地，所生成之近鄰的金屬彼此會一體化，因此形成粒子。另一方面，雖存在於纖維素纖維附近，但不與纖維素纖維鍵結而存在之金屬化合物等亦被還原而生成金屬。該金屬係迅速地與纖維素纖維表面之金屬一體化而形成金屬粒子。
還原反應可由公知之方法進行，較佳為以在還原金屬化合物的同時，不使金屬化合物與纖維素纖維之鍵結開裂的方式進行。如此之還原方法的例子，包含以氫所進行之氣相還原法，及使用了氫化硼鈉水溶液等之還原劑的液相還原法。
氣相還原中之時間、溫度等條件係適當調整，例如於50~60℃反應1~3小時左右即可。氣相還原反應，較佳以氧化纖維素纖維不含有水或溶劑的狀態進行。還原反應中，膜可維持固定於基材上、亦可為由基材剝離之狀態。液相還原的情況時，可由上述分散液得到膜，將其乾燥或不乾燥即進行還原反應。又，亦可不將分散液乾燥即進行液相還原反應。液相還原中之反應溫度較佳為4~40℃、更佳為室溫。
金屬粒子之平均粒子徑，可由穿透型電子顯微鏡像或X射線繞射求得。本發明中，金屬粒子之平均粒子徑由穿透型電子顯微鏡像求得時，較佳為1~50nm之範圍。具體而言，由穿透型電子顯微鏡像求得平均粒子徑之方法，可列舉準備纖維素纖維之穿透型電子顯微鏡像，由該像求得複數個金屬粒子之一次粒子之等效圓直徑，將此等之值平均而求得的方法。
纖維素纖維含有金屬離子及/或金屬粒子，可藉由掃描型電子顯微鏡像，及以強酸萃取之液體的ICP發光分光分析來確認。換言之，金屬離子於掃描型電子顯微鏡像中確認不到存在，另一方面於ICP發光分光分析中可確認到含有金屬。相對於此，例如上述金屬由離子還原而作為金屬粒子存在時，能夠以掃描型電子顯微鏡像確認到金屬粒子，故可判定金屬離子之有無。又，藉由掃描型電子顯微鏡像與元素分佈(element mapping)亦可判定金屬離子之有無。換言之，以掃描型電子顯微鏡像無法確認到金屬離子，但藉由進行元素分佈，可確認到存在金屬離子。
於前述載持金屬離子或金屬粒子之步驟中，前述金屬離子及/或金屬粒子相對於纖維素纖維之含量，合計較佳為10~100mg/g之範圍、更佳為15~80mg/g之範圍、特佳為20~60mg/g之範圍。合計少於10mg/g時，有抗病毒、消臭、抗菌機能不良的情況。另一方面，合計超過100mg/g時，可能於製造時金屬離子容易溶出，排水處理之負荷增大。
(3)打漿
本發明中之纖維素纖維，於進行前述變性處理之前起，至進行前述金屬載持處理後之間，亦可進行至少1次以上之打漿處理。此處，打漿處理係指對纖維賦予機械剪切力之處理。藉由打漿處理，纖維素纖維之一部分纖維化，表面積增大，藉此，一般而言可增強乾燥時之纖維間結合，此外本發明中，特別是於含金屬之纖維素纖維，藉由進行打漿處理，可進一步提高載持金屬離子及/或金屬粒子後之抗病毒、消臭、抗菌效果。
另一方面，打漿處理過度進行，使纖維素纖維過度微細化時，與紙漿摻合而進行抄紙時良率會降低，或未滯留(未殘留)於紙中，抗病毒、消臭、抗菌機能降低，故不佳。打漿程度之指標，可使用加拿大標準游離度(CSF)。具體而言，游離度(CSF)未達30ml時，因對薄片之良率減少，抗病毒、消臭、抗菌機能降低，游離度(CSF)超過600ml時，纖維化不充分，而有抗病毒、消臭、抗菌機能降低之虞。如此地，藉由使纖維素纖維之游離度(CSF)成為30~600ml，抗病毒、消臭、抗菌機能會提高。
對所得之氧化纖維素纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0。接著，以相對於氧化纖維素纖維1g之濃度成為1.0mmol/g的方式一邊攪拌一邊添加CuCl
2(富士軟片和光純藥公司製)，進一步攪拌30分鐘，藉以使氧化纖維素纖維含有Cu離子。
之後，重複2次之以充分量之水水洗、過濾，藉以去除未反應之金屬鹽，得到含浸有水的載持有Cu離子之氧化纖維素纖維(固體成分：30質量%)。所得之載持有Cu離子之氧化纖維素纖維中的金屬離子之含量為43.8mg/g，載持有Cu離子之氧化纖維素纖維之加拿大標準游離度(CSF)為500ml。
1-2.抗病毒性薄片之製造
如下述般製造薄片樣品。
(1)薄片1(樣品1-1)
作為纖維素纖維，係使用來自報紙再生紙之脫墨回收紙漿(日本製紙公司製、CSF：300ml)，於其中摻合實驗1所製造之載持有Cu離子之氧化纖維素纖維，使相對於纖維素纖維全體而言成為1重量%。使用Three-One Motor®以500rpm攪拌，同時相對於纖維素纖維100重量%而言，依次添加30重量%(固體成分)之輕質碳酸鈣、0.7重量%(固體成分)之聚氯化鋁、0.05重量%(固體成分)之紙強度提高劑，調製紙漿漿料。由所得之紙漿漿料，使用圓型手抄紙機製造每平方公尺的重量60g/m
2、紙厚120μm、灰分14%之薄片。
(2)薄片2(樣品1-2)
製造含有氧化澱粉(日本Corn Starch公司製、SK20)5重量%之上膠壓製液。將該上膠壓製液塗覆於薄片1之兩面，藉由常規方法乾燥(塗覆量：兩面合計為1g/m
2)。
(3)薄片3(樣品1-3)
於薄片2之單面，使用RI-Ⅰ型印刷機(石川島產業機械公司製)，以剛印刷之後的油墨上墨濃度成為1.0的方式將Vantean Eco墨(東洋油墨公司製)進行整面實地印刷。
(4)薄片4(樣品1-4)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為3重量%，除此以外係與薄片1同樣方式地製造薄片。
(5)薄片5(樣品1-5)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為5重量%，除此以外係與薄片1同樣方式地製造薄片。
(6)薄片6(樣品1-6)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為5重量%，除此以外係與薄片2同樣方式地製造薄片。
(7)薄片7(樣品1-7)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為5重量%，除此以外係與薄片3同樣方式地製造薄片。
(8)薄片8(樣品1-8)
作為纖維素纖維，係使用LBKP(日本製紙公司製、CSF：480ml)，於其中摻合實驗1所製造的載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為4重量%。相對於纖維素纖維100重量%而言，依次添加0.16重量%之上漿劑、1.50重量%之硫酸鋁、0.70重量%之陽離子化澱粉，調製紙漿漿料。由所得之紙漿漿料，使用抄紙機以速度250m/min抄紙，進行軋光處理，製造每平方公尺的重量71.0g/m
2、紙厚105μm之薄片。
(9)薄片9(樣品1-9)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為7重量%，除此以外係與薄片8同樣方式地製造薄片。
(10)薄片10(樣品1-10)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為10重量%，除此以外係與薄片8同樣方式地製造薄片。
(11)薄片11(樣品1-11、比較例)
不使用載持有Cu離子之氧化纖維素纖維，除此以外係與薄片1同樣方式地製造薄片。
(12)薄片12(樣品1-12、比較例)
不使用載持有Cu離子之氧化纖維素纖維，除此以外係與薄片8同樣方式地製造薄片。
(13)薄片13(樣品1-13、比較例)
摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為1重量%，除此以外係與薄片8同樣方式地製造薄片。
3-3.抗病毒性薄片之評估
對於所得之抗病毒性薄片，藉由以下所示之方法評估抗病毒機能等。
[銅之含量]
藉由ICP發光分光分析(ICP-OES)，藉由下述流程測定相對於薄片每1g之金屬離子及金屬粒子之含量(mg/g)。
(1) 於測定前將測定用試樣預先乾燥(50℃、1日)。
(2) 秤量經乾燥之測定用試樣0.1g，置入50mL容積之燒杯中。
(3) 以全吸管取濃硝酸10ml，添加於置入有測定用試樣的燒杯中，製成測定樣品液(10倍稀釋)。
(4) 30分鐘靜置後，通過針筒濾器由測定樣品液將纖維成分去除(過濾)。
(5) 將經過濾之測定樣品液以微吸管取1ml，添加於置入有蒸餾水49ml的試驗管中(50倍稀釋)。
(6) 將試驗管之蓋子蓋緊，振動攪拌。
(7) 使用ICP-OES(Agilent Technology公司製、ICP-OES 5110)，測定(定量)金屬離子及金屬粒子之含量。
(8) 由以ICP-OES之定量結果(ppb)，基於下式算出相對於薄片每1g而言之金屬離子及金屬粒子之含量(mg/g)。
(以ICP-OES之定量結果(ppb)×10×50)/(測定用試樣之重量(g))×1000/1000000000
[抗病毒機能]
抗病毒機能試驗，係以JIS L 1922：2016實施，算出抗病毒活性值(Mv)。供試驗之薄片之重量為0.4g，作為試驗病毒，係使用下述2種。
･流行性感冒病毒(H3N2、ATCC VR-1679)
･貓杯狀病毒(Strain：F-9 ATCC VR-782)
[消臭機能]
消臭機能試驗，係以SEK標章纖維製品認證基準(JEC301、纖維評價技術協議會)之方法，以氨為對象，以試驗資料大小100cm
2來實施。由以下基準評估消臭機能。
◎(非常良好) ：氨之減少率為80%以上
○(良好) ：氨之減少率為70%以上且未達80%
×(不良) ：氨之減少率為未達70%
[抗菌機能]
遵照JIS L1902「纖維製品之抗菌性試驗方法及抗菌效果」，以暈圈法(halo test)實施定性試驗。具體而言，係製作含大腸菌之洋菜培養基，於其上置放抗病毒性薄片之5cm×5cm試驗片，於37℃培養17小時後，確認試樣周邊有無產生試驗菌之「生長抑制帶」。由以下基準評估抗菌機能。
○：觀察到生長抑制帶，有抗菌機能。
×：未觀察到生長抑制帶，無抗菌機能。
由上述結果明顯可知，依照本發明，可製造具有優良之抗病毒機能、消臭機能、抗菌機能之抗病毒性薄片。
實驗2
2-1含金屬離子之纖維素纖維之製造
(1)纖維素纖維1
將來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)5.00g(絕對乾重)，添加至溶解有TEMPO(Sigma Aldrich公司)39mg(相對於絕對乾重1g之纖維素而言為0.05mmol)與溴化鈉514mg(相對於絕對乾重1g之纖維素而言為1.0mmol)的水溶液500ml中，攪拌至紙漿均勻分散。
接著，將次氯酸鈉水溶液添加至反應系統中使次氯酸鈉成為5.5mmol/g，於室溫開始氧化反應。反應中，系統內之pH降低，逐次添加3M氫氧化鈉水溶液，調整為pH10。於消耗次氯酸鈉，而系統內之pH不再變化的時間點結束反應(氧化反應所需時間：約90分鐘)。
將反應後之混合物以玻璃濾器過濾後，重複2次之以充分之水量進行水洗並過濾，藉以得到含浸有水的氧化纖維素纖維(固體成分：10質量%、紙漿產率：90%、羧基量：1.68mmol/g)。
對所得之氧化纖維素纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0。接著，以相對於氧化纖維素系纖維1g而言，濃度成為1.0mmol/g的方式一邊攪拌一邊添加CuCl
2(富士軟片和光純藥公司製)，進一步攪拌30分鐘，藉以使氧化纖維素系纖維含有Cu離子。
之後，重複2次之以充分之水量水洗並過濾，藉以去除未反應之金屬鹽，得到含浸有水的載持有Cu離子之纖維素纖維(固體成分：30質量%)。所得之含金屬離子之纖維素系纖維中的金屬離子之含量為40mg/g，含金屬離子之纖維素系纖維之游離度為500ml。
(2)纖維素纖維2
於可混合紙漿之攪拌機中，添加針葉樹漂白牛皮紙漿(NBKP、日本製紙製)乾燥質量計200g、氫氧化鈉乾燥質量計111g，以紙漿固體成分成為20%(w/v)的方式添加水。之後，於30℃攪拌30分鐘後，添加單氯乙酸鈉216g(以有效成分換算)。攪拌30分鐘後，昇溫至70℃，攪拌1小時。之後，取出反應物進行中和、洗淨，得到羧基甲基化纖維素系纖維(葡萄糖每單位之羧基甲基取代度：0.25)。
將上述操作所得之羧基甲基化纖維素系纖維(CM化纖維素系纖維)分散液之pH調整為8.5，以成為濃度1.0mmol/g(相對於CM化纖維素系纖維每1g)的方式，添加CuCl
2水溶液，攪拌15分鐘。藉此，使CM化纖維素系纖維含有Cu離子，藉由洗淨而去除未反應之金屬鹽，得到載持有Cu離子之纖維素系纖維(含金屬離子之纖維素系纖維)。相對於所得之含金屬離子之纖維素系纖維而言，金屬離子(Cu)之含量為31.3mg/g。
(3)纖維素纖維3
將磷酸二氫鈉二水合物6.75g、磷酸氫二鈉4.83g溶解於19.62g之水，得到反應液。於來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)中添加水，使濃度成為4%。之後，使用雙盤式磨漿機，打漿至CSF成為200ml、長度平均纖維長成為0.7mm。將藉此所得之纖維素懸浮液稀釋為0.3%，得到含水率90%、固體成分(絕對乾重質量)3g之紙漿薄片。將該紙漿薄片浸漬於前述反應液31.2g，以105℃之送風乾燥機加熱1小時後，進一步於150℃進行1小時加熱處理，對纖維素系纖維導入磷酸基。接著，對於對纖維素系纖維導入有磷酸基的紙漿薄片添加500ml之離子交換水，攪拌洗淨後，進行脫水。將脫水後之薄片以300ml之離子交換水稀釋，一邊攪拌，一邊一點一點地添加1N之氫氧化鈉水溶液5ml，得到pH為12~13之纖維素懸浮液。之後，將該纖維素懸浮液脫水，添加500ml之離子交換水進行洗淨。又，藉由以FT-IR進行紅外線吸收光譜測定，可見到於1230~1290cm
-1見到來自磷酸基之吸收，確認到磷酸基之附加。此時之磷酸基導入量，相對於微細纖維狀纖維素每1g(質量)而言為2.1mmol/g。
對上述磷酸酯化纖維素系纖維添加水，成為固體成分濃度2%之分散液，將pH調整至9.0後，以相對於磷酸酯化纖維素系纖維1g而言，濃度成為1.0mmol/g的方式，一邊攪拌一邊添加CuCl
2(富士軟片和光純藥製)，進一步攪拌30分鐘，藉以使磷酸酯化纖維素系纖維含有Cu離子。
對此，藉由重複2次之以充分之水量水洗並過濾，將未反應之金屬鹽去除，得到固體成分30質量%之含浸有水的載持有Cu離子之纖維素系纖維(含金屬離子之纖維素系纖維)。相對於磷酸酯化纖維素系纖維而言，金屬離子之含量為41mg/g。
(4)纖維素纖維4
將亞磷酸氫鈉･5水合物13g、尿素10.8g與水76.2g混合，調製反應液。將反應液100g與來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)乾燥重量10g混合，於105℃乾燥。使經乾燥之紙漿於170℃反應2小時，重複2次之水洗與過濾，得到含有由無機物所成之陽離子的經導入亞磷酸之酯的亞磷酸酯化纖維素系纖維。亞磷酸基導入量，相對於微細纖維狀纖維素每1g(質量)而言，為1.2mmol/g。
對上述亞磷酸酯化纖維素系纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0後，以相對於亞磷酸酯化纖維素系纖維1g而言，濃度成為1.0mmol/g的方式，一邊攪拌一邊添加CuCl
2(富士軟片和光純藥製)，進一步攪拌30分鐘，藉以使亞磷酸酯化纖維素系纖維含有Cu離子。
之後，藉由重複2次之以充分之水量水洗並過濾，將未反應之金屬鹽去除，得到固體成分30質量%之含浸有水的載持有Cu離子之纖維素系纖維(含金屬離子之纖維素系纖維)。相對於亞磷酸酯化纖維素系纖維而言，金屬離子之含量為42mg/g。
(5)纖維素纖維5
將胺磺酸20g、尿素10g與水100ml混合，調製反應液。對該反應液130g添加來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)2g(乾燥重量)，將所調製之漿料攪拌10分鐘。攪拌後，將漿料使用濾紙予以吸引過濾，製作紙漿薄片。將紙漿薄片置入設定為50℃之乾燥機中，乾燥至含水率成為平衡狀態。將乾燥後的紙漿於120℃加熱30分鐘。加熱反應後，將反應過的紙漿以純水洗淨至成為中性，調製經胺磺酸/尿素處理之磺化纖維素系纖維。此時之碸基之導入量為0.9mmol/g。
對上述磺化纖維素系纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0後，以相對於磺化纖維素系纖維1g而言，濃度成為0.5mmol/g的方式，一邊攪拌一邊添加CuCl
2(富士軟片和光純藥製)，進一步攪拌30分鐘，藉以使磺化纖維素系纖維含有Cu離子。
接著，重複2次之以充分之水量水洗並過濾，藉以將未反應之金屬鹽去除，得到固體成分30質量%之含浸有水的載持有Cu離子之纖維素系纖維(含金屬離子之纖維素系纖維)。相對於磺化纖維素系纖維而言，金屬離子之含量為21mg/g。
2-2.抗病毒性薄片之製造
於摻合有含金屬離子之纖維素系纖維5%、作為不含有金屬離子之纖維素系纖維(一般纖維素系纖維)的闊葉樹漂白牛皮紙漿(游離度600ml之LBKP；日本製紙製)95%者當中，進一步添加水，調製固體成分濃度0.5質量%之水分散體。
將其以圓型手抄紙機，以每平方公尺的重量成為30g/m
2的方式進行抄紙，以壓製裝置脫水，進一步藉由以筒式乾燥機於85℃進行乾燥，製作直徑約16cm之圓型抗病毒性薄片。
又，作為比較例，不摻合含金屬之纖維素系纖維，且使作為不含有金屬離子之纖維素系纖維的闊葉樹漂白牛皮紙漿(游離度600ml之LBKP；日本製紙股份有限公司)之摻合比例成為100%，除此以外係以與上述相同之方法製作薄片(樣品2-6)。
2-3.抗病毒性薄片之評估
對於所得之薄片樣品，以與實驗1相同之方法評估抗病毒特性。
由上述結果明顯可知，含有含金屬之纖維素系纖維的本發明之薄片，顯示高的抗病毒特性。另一方面，不含有含金屬之纖維素系纖維的薄片，抗病毒特性較低。
實驗3
3-1.含金屬離子之纖維素纖維之製造
將來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)5.00g(絕對乾重)，添加至溶解有TEMPO(Sigma Aldrich公司)39mg(相對於絕對乾重1g之纖維素而言為0.05mmol)與溴化鈉514mg(相對於絕對乾重1g之纖維素而言為1.0mmol)的水溶液500ml中，攪拌至紙漿均勻分散。
接著，於反應系中添加次氯酸鈉水溶液，使次氯酸鈉成為5.5mmol/g，於室溫開始氧化反應。反應中，系統內之pH會降低，逐次添加3M氫氧化鈉水溶液，調整為pH10。於消耗次氯酸鈉，而系統內之pH不再變化的時間點結束反應(氧化反應所需時間：90分鐘)。
將反應後之混合物以玻璃濾器過濾後，重複2次之以充分之水量水洗並過濾，藉以得到含浸有水的氧化纖維素纖維(固體成分：10質量%、紙漿產率：90%、羧基量為1.68mmol/g)。
對所得之氧化纖維素纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0。接著，以相對於氧化纖維素纖維1g而言，濃度成為1.6mmol/g的方式一邊攪拌一邊添加CuCl
2(富士軟片和光純藥公司製)，進一步攪拌30分鐘，藉以使氧化纖維素纖維含有Cu離子。
之後，重複2次之以充分之水量水洗並過濾，藉以去除未反應之金屬鹽，得到含浸有水的載持有Cu離子之纖維素纖維(固體成分：30質量%)。所得之含金屬離子之纖維素系纖維中的金屬離子之含量為40mg/g，含金屬離子之纖維素系纖維之游離度為500ml。
3-2.不織布之製造
摻合上述含金屬離子之纖維素系纖維10%、作為不含有金屬離子之纖維素系纖維(一般纖維素系纖維)之針葉樹漂白牛皮紙漿(游離度600ml之NBKP；日本製紙製)20%、將作為合成纖維之PET纖維(帝人Frontier製、Ecopet)切斷為纖維長5mm者30%、黏合纖維(芯鞘型聚酯系複合纖維、鞘部分之熔點：100~160℃、芯部分：聚對苯二甲酸乙二酯)40%，且於其中添加水，調製固體成分濃度0.5質量%之水分散體。
將其以圓型手抄紙機，以每平方公尺的重量成為30g/m
2的方式進行抄紙，以壓製裝置脫水，進一步藉由以筒式乾燥機於85℃進行乾燥，製作直徑約16cm之圓型不織布(樣品3-1)。
又，作為比較例，於製造不織布之步驟中，不摻合含金屬之纖維素系纖維，且使不含有金屬離子之纖維素系纖維(游離度600ml之NBKP紙漿、日本製紙製)的摻合比例成為30%，除此以外係以與上述相同之方法製作不織布(樣品3-2)。
3-3.不織布之評估
對於所得之不織布，與實驗1同樣地評估抗病毒特性。
由上述結果明顯可知，含有含金屬之纖維素系纖維及合成纖維之不織布，顯示高的抗病毒特性。另一方面，不含有含金屬之纖維素系纖維之不織布，未顯示抗病毒特性。
實驗4
4-1.載持有Cu離子之氧化纖維素纖維之製造
將來自針葉樹之經漂白的未打漿牛皮紙漿(白色度85%)275BDkg(絕對乾重)添加至溶解有TEMPO(Sigma Aldrich公司製)1.07kg(相對於絕對乾重1g之纖維素而言為0.25mmol)與溴化鈉28.3kg(相對於絕對乾重1g之纖維素而言為1.0mmol)的水溶液500ml中，攪拌至紙漿均勻分散。
接著，於反應系統中添加次氯酸鈉水溶液，使次氯酸鈉成為5.2mmol/g，於室溫開始氧化反應。反應中，系統內之pH會降低，逐次添加3M氫氧化鈉水溶液，調整為pH10。於消耗次氯酸鈉，系統內之pH不再變化的時間點結束反應(氧化反應所需時間：約90分鐘)。
將反應後之混合物以螺旋式壓機脫水後，重複2次之以充分之水量水洗並過濾，藉以得到含浸有水之氧化纖維素纖維(固體成分：10質量%、紙漿產率：90%、羧基量：1.68mmol/g)。
對所得之氧化纖維素纖維添加水，成為固體成分濃度2%之分散液，將pH調整為9.0。接著，以相對於氧化纖維素纖維1g而言，濃度成為1.0mmol/g的方式一邊攪拌一邊添加CuCl
2(富士軟片和光純藥製)，進一步攪拌30分鐘，藉以使氧化纖維素纖維含有Cu離子。
之後，重複2次之以充分量之水水洗、過濾，藉以去除未反應之金屬鹽，得到含浸有水的載持有Cu離子之氧化纖維素纖維(固體成分：30質量%)。所得之載持有Cu離子之氧化纖維素纖維中的金屬離子之含量為43.8mg/g，載持有Cu離子之氧化纖維素纖維之加拿大標準游離度(CSF)為500ml。
4-2.抗病毒性薄片之製造
(1)樣品4-1
作為纖維素纖維係使用LBKP(日本製紙製、CSF：470ml)，於其中摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為6重量%。於其中添加輕質碳酸鈣，使紙中灰分成為5%。相對於纖維素纖維100重量%而言，添加0.80重量%之陽離子化澱粉，調製紙漿漿料。由所得之紙漿漿料，使用抄紙機以速度540m/min進行抄製。
相對於氧化澱粉(日本Corn Starch製、SK20)100重量份而言，添加原鹽3.5重量份，調製調整為固體成分濃度11質量%之表面處理液，使用閘輥塗佈器(GRC)進行塗覆(兩面塗佈量：約1.6g/m
2)。乾燥後進行軋光處理，得到每平方公尺的重量約80g/m
2之紙。
(2)樣品4-2
作為纖維素纖維係使用LBKP(日本製紙製、CSF：470ml)，於其中摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為3重量%(輕質碳酸鈣無摻合)。相對於纖維素纖維100重量%而言，添加0.80重量%之陽離子化澱粉，調製紙漿漿料。由所得之紙漿漿料，使用抄紙機以速度540m/min進行抄製。
相對於氧化澱粉(日本Corn Starch製、SK20)100重量份而言，添加陰離子性上漿劑(播磨化成)5.6份、原鹽3.5重量份，調製調整為固體成分濃度11質量%之表面處理液，使用閘輥塗佈器(GRC)進行塗覆(兩面塗佈量：約1.6g/m
2)。乾燥後進行軋光處理，得到每平方公尺的重量約80g/m
2之紙。
(3)樣品4-3
除了添加滑石，使紙中灰分成為5%以外，係與樣品4-2同樣地進行抄製。
(4)樣品4-4
以LBKP(日本製紙製、CSF：480ml)：NBKP(日本製紙製、CSF：590ml)=72：24的方式混合，作為纖維素纖維，於其中摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為4重量%。相對於纖維素纖維100重量%而言，依次添加0.16重量%之上漿劑、1.50重量%之硫酸鋁(硫酸鋁)、0.70重量%之陽離子化澱粉，調製紙漿漿料。由所得之紙漿漿料，使用抄紙機以速度250m/min進行抄紙，進行軋光處理，製造薄片(每平方公尺的重量：71.0g/m
2、紙厚：105μm)。
(5)樣品4-5
作為纖維素纖維係使用LBKP(日本製紙製、CSF：470ml)，於其中摻合載持有Cu離子之氧化纖維素纖維，使得相對於纖維素纖維全體而言成為3重量%。於其中添加輕質碳酸鈣，使紙中灰分成為10%。相對於纖維素纖維100重量%而言，添加0.80重量%之陽離子化澱粉，調製紙漿漿料。由所得之紙漿漿料，使用抄紙機以速度540m/min進行抄製。
相對於氧化澱粉(日本Corn Starch製、SK20)100質量份而言，添加陰離子性上漿劑(播磨化成)1.4份、原鹽3.5質量份，調製調整為固體成分濃度11質量%之表面處理液，使用閘輥塗佈器(GRC)進行塗覆(兩面塗佈量：約1.6g/m
2)。乾燥後進行軋光處理，得到每平方公尺的重量約80g/m
2之紙。
4-3.抗病毒性之評估
對於所得之薄片，與實驗1同樣地評估抗病毒機能等。又，就金屬溶出量等而言係如下述般評估。
[每平方公尺的重量]根據JIS P8124進行測定。
[紙厚]根據JIS P8118進行測定。
[ISO白色度]根據JIS P8148，使用色差計(村上色彩、CMS-35SPX)進行測定。
[ISO不透明度]根據JIS P8149進行測定。
[色相]根據JIS P8150進行測定。
[史托克上漿度]根據JIS P8122進行測定。
[筆書寫上漿度]根據J.TAPPI No.12進行測定。
[紙面pH]
於pH計(HORIBA製、F-24型)安裝表面測定用不玻璃電極(HORIBA製、平面型pH複合電極6261-10C)，由下述流程測定。
(1) 將電極以純水洗淨。
(2) 於電極尖端滴附1滴純水。
(3) 使電極尖端連接到測定試樣之表面，評估1分鐘後之值。
(4) 重複(1)~(3)5次，紀錄其平均值，作為紙面pH。
[金屬溶出量]
對於銅及鋁，藉由ICP發光分光分析(ICP-OES)，由下述流程測定薄片每0.8g之金屬離子及金屬粒子於超純水100ml中之溶出量。
(1) 於測定前將測定用試樣預先乾燥(50℃、1日)。
(2) 於300mL容積之杯中置入超純水(30℃、100ml)。
(3) 將經乾燥之測定用試樣0.8g置入(2)之杯中並上蓋。
(4) 於30℃靜置30分鐘後，通過針筒濾器由測定樣品液將纖維成分去除(過濾)。
(5) 將經過濾之測定樣品液49ml置入試驗管中，以微吸管添加濃硝酸1ml。
(6) 將試驗管之蓋子蓋緊，振動攪拌。
(7) 使用ICP-OES(Agilent Technology公司製、ICP-OES 5110)，測定(定量)金屬離子及金屬粒子之含量。
(8) 由以ICP-OES之定量結果，基於下式算出薄片每0.8g之金屬離子及金屬粒子對超純水100ml中之溶出量。
以ICP-OES之定量結果(ppb)×50/49
[消臭機能]
消臭機能試驗，係以SEK標章纖維製品認證基準(JEC301、纖維評價技術協議會)之方法，以硫化氫為對象，以試驗資料大小100cm
2實施。由以下基準評估消臭機能。
◎(非常良好) ：硫化氫之減少率為80%以上
○(良好) ：硫化氫之減少率為70%以上且未達80%
×(不良) ：硫化氫之減少率為未達70%
[抗菌機能]
遵照JIS L1902「纖維製品之抗菌性試驗方法及抗菌效果」，以暈圈法實施定性試驗。具體而言，製作含有大腸菌及金黃色葡萄球菌之洋菜培養基，於其上放置抗病毒性薄片之5cm×5cm試驗片，於37℃培養17小時後，確認試樣周邊有無產生試驗菌之「生長抑制帶」。由以下基準評估抗菌機能。
○：觀察到生長抑制帶，有抗菌機能。
×：未觀察到生長抑制帶，無抗菌機能。
由上述結果明顯可知，依照本發明，可製造具有優良之抗病毒機能、消臭機能、抗菌機能之抗病毒性薄片。
The cellulose fiber-containing sheet of the present invention is a sheet having a single-layer structure or a multi-layer structure with antiviral properties. Specifically, the antiviral sheet of the present invention has an antiviral activity value (Mv) against influenza virus or feline calicivirus measured based on JIS L 1922:2016 (Antiviral Test Method for Fiber Products): 2.0 or more, and the antiviral activity value is more preferably 2.5 or more or 3.0 or more. In addition to antiviral properties, the antiviral sheet of the present invention may have one or more other functions. Examples of the functions of the antiviral sheet of the present invention include deodorization, antibacterial, heat resistance, moisture resistance, weather resistance, solvent resistance, abrasion resistance, electromagnetic wave blocking, etc. In a preferred aspect of the present invention, Antiviral flakes with deodorizing and/or antibacterial properties. The application of the antiviral sheet of the present invention is not particularly limited, and can be used for any application that requires an antiviral function. The application of the antiviral sheet includes, for example, packaging materials (paper containers, cartons, resin films, wrapping papers, etc.), building materials (wallpaper, decorative paper, liner paper, etc.), sanitary products (diapers, sanitary products, wipes, masks, etc.) , small towels, gauze, cotton sticks, etc.), daily necessities (deodorant materials, aroma materials, food filters, air filters, placemats, bracket guard plates, tablecloths, drainage nets, kitchen towels, baking paper, foam Suction sheets, kitchen cloths, cloth towels, aprons, heat-proof pot clips, toilet seat paper, scatter prevention sheets for toilet floors, bathroom floor mats, wet wipes, disposable slippers, carpet substrates, insoles, suit dust jackets, tote bags , condensation sheets, book covers, vacuum cleaner paper bags, notes, bookmarks, notebooks, notebook covers, pet pads, disposable pads, pillow covers, quilt covers, wipes, etc.), industrial supplies (industrial filters, industrial wipes, automobiles Interior materials, etc.), medical products (masks, protective clothing, surgical gowns (surgical caps/skirts/tops and pants), antibacterial pads, cleaning wipes, medical tapes, etc.), clothing (disposable underwear, etc.), gardening / Agricultural materials (horticultural sheet, agricultural sheet, seedbed sheet, fruit bag, etc.), headrest cover (high-speed rail or automobile), other paper products (calendar, etc.), etc. The antiviral sheet of the present invention may have a single-layer structure or a multi-layer structure, and in the case of a multi-layer structure, at least one layer must contain cellulose fibers. Moreover, it is preferable that the cellulose fiber which supports the metal ion and/or metal particle mentioned later is contained in the outermost layer. The antiviral sheet of the present invention contains cellulose fibers, the cellulose fibers preferably have an anionic group on the surface, and contains a material selected from the group consisting of Ag, Au, Pt, Pd, Ni, Mn, Fe, Ti, Al, Zn and Cu One or more metal ions and/or metal particles of an element group. The anionic group is preferably a carboxyl group or a carboxylate group, and the metal ion is preferably ionically bonded. In the present invention, it is preferable to have at least one layer containing cellulose fibers supporting metal ions and/or metal particles (hereinafter also referred to as "metal-containing cellulose fibers"). The raw materials other than the metal-containing cellulose fibers are not particularly limited, and known raw materials can be used. As an example, it may contain one or more cellulose fibers that do not support metal ions or metal particles (hereinafter also referred to as "general cellulose fibers"), synthetic fibers, or other materials such as resins and inorganic substances. The flakes of the present invention may contain fillers. The content of the filler in the flakes is not particularly limited, but preferably within the range of 20% by weight of the weight of the flakes, and may also be 10% by weight or less or 5% by weight or less. Examples of fillers include heavy calcium carbonate, light calcium carbonate, silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, pumice powder, pumice balloon, aluminum hydroxide, magnesium hydroxide, Basic magnesium carbonate, dolomite, calcium sulfate, potassium titanate, barium sulfate, calcium sulfite, talc, clay, mica, asbestos, calcium silicate, montmorillonite, bentonite, graphite, aluminum powder, molybdenum sulfide, etc. Other materials are not particularly limited, for example, bulk builders, dry paper strength enhancers, wet paper strength enhancers, water drainage enhancers, yield enhancers, dyes, sizing agents, aluminum sulfate, etc. can be used as required. The content of other materials other than fillers is preferably not more than 10% by weight of the sheet weight in total. In addition, the manufacturing method of a sheet is not specifically limited, A well-known method can be used. For example, there may be a method of discharging water in which the raw material is dispersed and dehydrating by pressure or heat (so-called wet method), and a method of discharging the raw material in a dry state and similarly forming flakes by pressure or heat (so-called wet method). dry) any method. Since cellulose fiber is hydrophilic, it is preferable to form a sheet by a wet process. In the present invention, a sheet may be produced by mixing the above-mentioned cellulose fibers with pulp slurry (stock) in the same manner as a normal paper sheet, and making paper using the sample. For papermaking, a well-known papermaking machine such as a Fourdrinier paper machine, a sandwich paper machine, and a rotary screen paper machine can be used, and the papermaking conditions are not limited. In addition, the antiviral sheet of the present invention may be subjected to known surface treatment such as calendering treatment as necessary. For the surface treatment, a known treatment device can be used, and the conditions thereof are not limited. In the antiviral sheet of the present invention, a coating layer (transparent coating layer) that does not contain pigments can also be provided on the surface of the sheet as required. The sheet of the present invention preferably has a transparent coating layer on one side or both sides of the sheet, and more preferably has a transparent coating layer containing at least starch. By having the transparent coating layer, when the sheet of the present invention is a paper, it is possible to obtain a paper which is particularly excellent in smoothness, surface strength, and printability. In addition, although the reason is not clear, the sheet of the present invention has excellent antiviral activity even if the sheet surface is covered with a transparent coating layer. The coating amount of the transparent coating layer, in terms of solid content per single side, is preferably 0.01-3.0 g/m 2 , more preferably 0.1-2.0 g/m 2 . Clear coating, for example, by coating using a sizing press, a gate roll coater, a premetering size press, a curtain coater, a spray coater, etc. A machine (coating machine) is formed by applying a coating liquid on a sheet. The solid content concentration of the transparent coating solution is preferably 2 to 14 wt % from the viewpoint of coating solution boiling or coating amount adjustment, and the B-type viscosity (30°C, 60 rpm) at a solid content concentration of 5 wt % It is preferably 5 to 450 mPa･s, more preferably 10 to 300 mPa･s. In the present invention, starch refers to a mixture comprising amylose and amylopectin, and generally, the mixing ratio varies depending on the plant of the starch raw material. In the present invention, starches also include high molecular compounds derived from starch. As the polymer, starch denatured, modified, processed, or the like can be exemplified. As starches, for example, preferably include raw starch, oxidized starch, esterified starch, cationized starch, self-made starch produced by thermochemical denaturation or enzymatic denaturation in a paper factory using acetylated tapioca starch as a raw material Modified starch such as modified starch, formaldehyde starch, hydroxyethylated starch and other modified starch. For the transparent coating layer of the present invention, for example, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, polyacrylamide, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, Acetyl acetylated polyvinyl alcohol and other denatured alcohols, styrene-butadiene-based copolymers, polyvinyl acetate, vinyl chloride-vinyl acetate-based copolymers, polyvinyl chloride, polyvinylidene chloride, polyvinylidene chloride Acrylates etc. may be used in combination of 2 types or 3 or more types. Furthermore, for the purpose of improving the sizing properties, a styrene-based sizing agent, an olefin-based sizing agent, an acrylate-based sizing agent, a styrene-acrylic sizing agent, a cationic sizing agent, etc. may be used in combination on the surface Sizing agent. In the present invention, various auxiliary agents such as dispersants, tackifiers, water-retaining materials, antifoaming agents, water-resistance agents, colorants, and conductive agents, etc., which are blended with ordinary clear coating films, are appropriately used as needed. The weight per square meter of the antiviral sheet of the present invention is not particularly limited, and can be set in a general range as required, preferably in the range of 10-1000 g/m 2 , more preferably in the range of 10-300 g/m 2 , It can also be in the range of 15~200g/m 2 or 20~90g/m 2 . When the weight per square meter is more than 1000 g/m 2 , the ease of bending or ease of cutting peculiar to the sheet may be poor, which may become a problem. When the sheet has a multilayer structure, when the weight per square meter of each layer is 10 g/m 2 or more, it is preferable from the viewpoint of producing a sheet that is uniform and has the minimum strength during production. The thickness of the antiviral sheet is preferably in the range of 20 to 500 μm, more preferably in the range of 30 to 200 μm. When the sheet has a multilayer structure, the thickness of each layer is preferably 20 μm or more, from the viewpoint of producing a uniform sheet. The density of the sheet is not particularly limited. When the antiviral sheet of the present invention has a multi-layer structure, each layer can be formed by laminating each layer by a known method, or by laminating the layers in sequence. In addition, the sheet can also be produced by a so-called simultaneous multilayer method in which a plurality of layers are formed at one time while simultaneously discharging the raw materials of each layer. The method of following each layer is not particularly limited, and a known method can be used. For example, the method of using an adhesive agent, the method of fuse|melting layers by passing between hot rolls or blowing hot air, etc. are mentioned. When the antiviral sheet of the present invention has a multi-layer structure, the outermost layer may be processed by more than one layer lamination, and, like the so-called adhesive label sheet, the outermost layer may have an adhesive layer for bonding with other substrates. In addition, a single layer of sheets may be simply laminated, or one or more layers may have a three-dimensional structure like a carton. The antiviral sheet of the present invention can also be printed on the outermost layer as required. When the antiviral sheet of the present invention contains cellulose fibers supporting metal ions and/or metal particles, the sheet preferably contains 0.20 mg/g or more of metal ions and metal particles in total, more preferably 0.25 mg/g or more per 1 g of the sheet. , and more preferably 0.30 mg/g or more, and most preferably 0.60 mg/g or more. In addition, the total content of metal ions and metal particles per 1 g of the flakes is preferably 6.3 mg/g or less, and may be 5.0 mg/g or less or 4.0 mg/g or less. By making the total content of metal ions and/or metal particles per 1 g of flakes to be 0.20 mg/g or more and 6.3 mg/g, flakes with excellent antiviral function and the like can be easily obtained, and excess metal ions and/or excess can be suppressed. or increased environmental load or flake coloration caused by metal particles. The content of metal ions and metal particles in the antiviral sheet can be measured (quantified) by, for example, ICP optical emission spectrometry (ICP-OES). Further, the content of the metal-containing cellulose fibers is preferably 0.5% by weight or more with respect to the antiviral sheet. When the content of the metal-containing cellulose fibers is too small, a sufficient antiviral function may not be imparted. The upper limit of the above-mentioned content is not particularly limited, and can be appropriately adjusted according to the required degree of antiviral, deodorizing, antibacterial functions, etc., and can also be 100% by weight. The content of the metal-containing cellulose fibers may be, for example, 1 to 80% by weight, 2 to 60% by weight, 3 to 40% by weight, or the like. Furthermore, as described above, the content of the metal-containing cellulose fibers is preferably 0.5% by weight or more with respect to the antiviral sheet, so the content of general cellulose fibers in the antiviral sheet is preferably 99.5% by weight or less . The lower limit of the content of general cellulose fibers is not particularly limited, and general cellulose fibers may not be included. The antiviral sheet of the present invention contains cellulose fibers. The type of cellulose fibers in the present invention is not particularly limited, and any type may be used as required. Moreover, 2 or more types of cellulose fibers among these can be mixed in arbitrary ratios and can be used. The source of cellulose fibers is not particularly limited, and examples of cellulose fibers from plants, from animals, from algae, from microorganisms, etc., are particularly preferred, among which cellulose fibers from plants or from microorganisms are particularly preferred, and those from plants are particularly preferred. of cellulose fibers. Cellulosic fibers derived from plants, for example, wood, bamboo, hemp, jute, kenaf, agricultural residues, pulp (conifer unbleached kraft pulp (NUKP), conifer bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), Hardwood Bleached Kraft Pulp (LBKP), Conifer Unbleached Sulfite Pulp (NUSP), Conifer Bleached Sulfite Pulp (NBSP), Thermomechanical Pulp (TMP), Recycled Pulp, Recycled Pulp, etc.), from Animal cellulose fibers include, for example, cellulose fibers derived from ascidians, and cellulose fibers derived from microorganisms include, for example, cellulose fibers derived from acetic acid bacteria (acetic acid bacteria). When the sheet of the present invention is paper, it preferably contains LBKP and/or recycled pulp as cellulose fibers. LBKP or recycled pulp has a short fiber length, and by containing these pulps, paper with excellent smoothness can be obtained, and the thus obtained paper is excellent in surface properties or printability (especially printing surface feel). The number-average fiber diameter and number-average fiber length of the cellulose raw material used in the present invention are not particularly limited, and any number-average fiber diameter and number-average fiber length can be used as required. Moreover, two or more types of cellulose fibers having different number-average fiber diameters and number-average fiber lengths can be mixed and used in arbitrary ratios. As an example, in the case of softwood kraft pulp (NBKP), which is one of the general pulps, the number-average fiber diameter is about 30 to 60 μm and the number-average fiber length is about 3 to 5 mm. In the case of hardwood bleached kraft pulp (LBKP), The number average fiber diameter is about 10 to 30 μm, and the number average fiber length is about 1 to 2 mm. (1) Modified cellulose fibers of cellulose fibers, each glucose unit has 3 hydroxyl groups, and can be subjected to various chemical denaturation treatments. In the present invention, it is preferable to perform a chemical denaturation treatment having an anionic group after the treatment. Cellulose fibers into which anionic groups are introduced include, for example, oxidized cellulose fibers having carboxyl groups or carboxylate groups, phosphated cellulose fibers having phosphoric acid groups, phosphite cellulose fibers having phosphorous acid groups, and Sulfonated cellulose fibers of sulfuric acid group, etc. In the present invention, in order to introduce metal ions or metal particles into at least a part of the cellulose fibers in the following step, it is preferable to perform denaturation (oxidation) to introduce a carboxyl group or a carboxylate group into at least a part of the cellulose fibers. In addition, in this specification, the anionic group introduced into the cellulose fiber is also called an acid group. Here, a carboxyl group means a group represented by -COOH, and a carboxylate group means a group represented by -COO-. The opposite ion of the carboxylate group is not particularly limited. As described later, when the metal particles are formed through an ionic bond with a carboxylate group, the metal ion is a counter ion. The amount of anionic groups in the cellulose fibers having anionic groups (acid groups) can be measured by the following method as an example. 60 ml of a 0.5 mass % slurry (aqueous dispersion) of a cellulose fiber sample having an anionic group (acid group) was prepared, and a 0.1 M aqueous hydrochloric acid solution was added to make pH 2.5, and then a 0.05 N aqueous sodium hydroxide solution was dropped to measure the electrical conductivity. When the pH became 11, the amount of sodium hydroxide (a) consumed in the neutralization stage of the weak acid whose change in conductivity was moderate was measured. Next, the anionic group amount [mmol/g] of the cellulose fiber which has an anionic group (acid group) was computed using the following formula. In the formula, x is a value corresponding to the valence of an acid group, 1 in the case of a carboxyl group, a carboxylate group, a phosphorous acid group, and a sulfonic acid group, and 2 in the case of a phosphoric acid group. a[ml]×0.05/weight of cellulose fibers having anionic groups (acid groups) [g]/x In addition, in carboxyalkylated cellulose fibers having carboxyalkyl groups, anionic groups are treated by carboxyalkylation to When quantifying the amount, the following methods can be used. (1) Precisely weigh about 2.0 g of carboxymethyl cellulose (absolute dry weight), and put it into a 300 mL conical flask with a stopper. (2) Add 100 mL of nitric acid methanol solution obtained by adding 100 mL of super concentrated nitric acid to 1000 mL of methanol, and shake for 3 hours to make carboxymethylcellulose salt (carboxymethylated cellulose) into hydrogen-form carboxymethylated cellulose. (3) Precisely weigh 1.5~2.0 g of hydrogen-type carboxymethyl cellulose (absolute dry weight), and put it into a 300-mL conical flask with a stopper. (4) Wet hydrogen-form carboxymethyl cellulose with 15 mL of 80% methanol, add 100 mL of 0.1N NaOH, and shake at room temperature for 3 hours. (5) Using phenolphthalein as an indicator, reverse titrate excess NaOH with 0.1N H 2 SO 4 . (6) Calculate the degree of carboxyalkyl substitution (DS) by the following formula: A=[(100×F'-(0.1N H 2 SO 4 )(mL)×F)×0.1]/(hydrocarboxyalkane Absolute dry weight of cellulose (g)) DS=0.162×A/(1-0.058×A) A: The amount of 1N NaOH required for neutralization of 1 g of hydrogen carboxyalkylated cellulose (mL) F': Factor of 0.1N NaOH F: Factor of 0.1N H 2 SO 4 Below, the method of introducing anionic groups into glucose units on the surface of cellulose fibers will be described. (1-1) Oxidation In the present invention, the method for denaturation (oxidation) of introducing carboxyl groups or carboxylate groups into cellulose fibers is not particularly limited as long as the denatured cellulose fibers contain carboxyl groups or carboxylate groups. A known method is used. As an example, a method of oxidizing a cellulose raw material in water using an oxidizing agent in the presence of a substance selected from the group consisting of an N-oxy compound, a bromide, an iodide, or a mixture thereof can be mentioned. According to this method, the primary hydroxyl group at the C6 position of the glucoranose ring on the cellulose surface is selectively oxidized to generate a group selected from the group consisting of an aldehyde group, a carboxyl group and a carboxylate group. The concentration of the cellulose raw material during the reaction is not particularly limited, but is preferably 5% by weight or less. N-oxyl compounds refer to compounds that can generate nitroxyl radicals. As a nitroxyl radical, 2,2,6,6- tetramethylpiperidine 1-oxyl group (TEMPO) is mentioned, for example. Any N-oxy compound can be used as long as it promotes the intended oxidation reaction. The amount of the N-oxy compound used is not particularly limited as long as it is a catalytic amount capable of oxidizing the cellulose fibers. For example, it is preferably 0.01 mmol or more, more preferably 0.02 mmol or more, relative to 1 g of absolute dry weight of cellulose. The upper limit is preferably 10 mmol or less, more preferably 1 mmol or less, and still more preferably 0.5 mmol or less. Therefore, the use amount of the N-oxy compound is preferably 0.01-10 mmol, more preferably 0.01-1 mmol, and still more preferably 0.02-0.5 mmol relative to the absolute dry weight of 1 g of cellulose. Bromide means a compound containing bromine, and examples thereof include alkali metal bromides that can be dissociated and ionized in water, such as sodium bromide. In addition, the iodide refers to a compound containing iodine, and examples thereof include alkali metal iodide. The amount of bromide or iodide used may be selected within a range that can promote the oxidation reaction. The total amount of bromide and iodide is preferably 0.1 mmol or more, more preferably 0.5 mmol or more, relative to 1 g of absolute dry weight of cellulose. The upper limit is preferably 100 mmol or less, more preferably 10 mmol or less, and still more preferably 5 mmol or less. Therefore, the total amount of bromide and iodide is preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and still more preferably 0.5 to 5 mmol relative to 1 g of absolute dry weight of cellulose. The oxidizing agent is not particularly limited, and examples thereof include halogens, hypohalous acids, hypohalous acids, perhalic acids, salts thereof, oxyhalides, peroxides, and the like. Among them, hypohalous acid or its salt is preferable, hypochlorous acid or its salt is more preferable, and sodium hypochlorite is still more preferable because it is inexpensive and has little environmental load. The amount of the oxidizing agent used is preferably 0.5 mmol or more, more preferably 1 mmol or more, and still more preferably 3 mmol or more, relative to 1 g of absolute dry weight of cellulose. The upper limit is preferably 500 mmol or less, more preferably 50 mmol or less, and still more preferably 25 mmol or less. Therefore, the use amount of the oxidizing agent is preferably 0.5-500 mmol, more preferably 0.5-50 mmol, still more preferably 1-25 mmol, and most preferably 3-10 mmol, relative to the absolute dry weight of 1 g of cellulose. When an N-oxy compound is used, the usage amount of the oxidizing agent is preferably 1 mol or more with respect to 1 mol of the N-oxy compound, and the upper limit is preferably 40 mol. Therefore, the usage-amount of an oxidizing agent is preferably 1-40 mol with respect to 1 mol of N-oxyl compound. Conditions such as pH and temperature during the oxidation reaction are not particularly limited, but generally, the oxidation reaction proceeds efficiently even under relatively mild conditions. The reaction temperature is preferably 4°C or higher, more preferably 15°C or higher. The upper limit is preferably 40°C or lower, more preferably 30°C or lower. Therefore, the temperature is preferably 4 to 40°C, and may be about 15 to 30°C, that is, room temperature. The pH of the reaction solution is preferably 8 or more, more preferably 10 or more. The upper limit is preferably 12 or less, more preferably 11 or less. Therefore, the pH of the reaction solution is preferably about 8 to 12, more preferably about 10 to 11. In general, as the oxidation reaction proceeds, carboxyl groups are generated in cellulose, so that the pH of the reaction solution tends to decrease. Therefore, in order to efficiently advance the oxidation reaction, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to maintain the pH of the reaction solution within the above-mentioned range. The reaction medium at the time of oxidation is preferably water, for reasons such as ease of handling and difficulty in generating side reactions. The reaction time of the oxidation can be appropriately set according to the degree of progress of the oxidation, and is usually 0.5 hour or more. The upper limit is usually 6 hours or less, preferably 4 hours or less. Therefore, the reaction time of the oxidation is usually about 0.5 to 6 hours, for example, about 0.5 to 4 hours. Oxidation can also be carried out by dividing into two or more stages of reactions. For example, by filtering the obtained oxidized cellulose after the first-stage reaction, and re-oxidizing it under the same or different reaction conditions, the reaction can be prevented from being hindered by the salt by-produced in the first-stage reaction. Oxidation proceeds efficiently. Another example of the method of denaturation (oxidation) of introducing a carboxyl group or a carboxylate group includes a method of oxidizing by ozone treatment. By this oxidation reaction, at least the hydroxyl groups at the 2-position and the 6-position of the vitiranose ring constituting the cellulose are oxidized, and the cellulose chain is decomposed. Ozone treatment is generally carried out by contacting an ozone-containing gas with a cellulose feedstock. The ozone concentration in the gas is preferably 50 g/m 3 or more. The upper limit is preferably 250 g/m 3 or less, more preferably 220 g/m 3 or less. Therefore, the ozone concentration in the gas is preferably 50-250 g/m 3 , more preferably 50-220 g/m 3 . The amount of ozone added is preferably 0.1 part by mass or more, more preferably 5% by weight or more, with respect to 100% by weight of the solid content of the cellulose raw material. The upper limit is usually 30% by weight or less. Therefore, the amount of ozone added is preferably 0.1 to 30% by weight, more preferably 5 to 30% by weight, relative to 100% by weight of the solid content of the cellulose raw material. The ozone treatment temperature is usually 0°C or higher, preferably 20°C or higher. The upper limit is usually 50°C or lower. Therefore, the ozone treatment temperature is preferably 0 to 50°C, more preferably 20 to 50°C. The ozone treatment time is usually 1 minute or more, preferably 30 minutes or more. The upper limit is usually 360 minutes or less. Therefore, the ozone treatment time is usually about 1 to 360 minutes, preferably about 30 to 360 minutes. If the conditions of ozone treatment are within the above-mentioned range, excessive oxidation and decomposition of cellulose can be prevented, and the yield of oxidized cellulose can be improved. The resultant obtained after the ozone treatment may be further subjected to an additional oxidation treatment using an oxidizing agent. The oxidizing agent used in the additional oxidation treatment is not particularly limited, and examples thereof include chlorine-based compounds such as chlorine dioxide and sodium chlorite; oxygen, hydrogen peroxide, persulfuric acid, peracetic acid, and the like. As a method of the oxidation treatment, for example, a method of dissolving such an oxidizing agent in a polar organic solvent such as water or alcohol to prepare an oxidizing agent solution, and immersing the cellulose raw material in the oxidizing agent solution can be mentioned. The amount of anionic groups of the oxidized cellulose fibers having carboxyl groups or carboxylate groups is preferably 0.01 to 3.0 mmol/g, more preferably 0.20 to 2.2 mmol/g. When the anion group is less than 0.01mmol/g, in the step of supporting metal ions or metal particles on the cellulose fibers described later, the amount of metal particles present on the surface of the cellulose fibers is insufficient, which has antiviral, deodorizing, and antibacterial functions. bad condition. On the other hand, when the anion group exceeds 3.0 mmol/g, aggregation of metal particles may occur, and antiviral, deodorizing, and antibacterial functions may be poor, and cellulose may be easily cut as a side reaction during the oxidation reaction, resulting in production rate reduction. The amount of anionic groups (carboxyl groups, carboxylate groups) contained in the oxidized cellulose fibers can be adjusted by controlling the oxidation conditions such as the amount of the oxidizing agent added and the reaction time. (1-2) Etherification As etherification, any method can be used as long as it is a method in which a carboxyl group or a carboxylate group is contained in the functional group after the reaction for the convenience of introducing metal ions into the cellulose fibers in the subsequent step. , known methods can be used. Examples include carboxyalkyl etherification such as carboxymethyl (ether), carboxyethyl (ether), carboxypropyl (ether), and carboxybutyl (ether), or carboxyphenyl (ether) example. Among them, the method of carboxymethylation is demonstrated below as an example. The method of carboxymethylation is not particularly limited, and a known method can be used. For example, a method of mercerizing a cellulose raw material as a hair base raw material, followed by etherification can be mentioned. Common solvents are used for the carboxymethylation reaction. Examples of the solvent include water, alcohols (eg, lower alcohols), and mixed solvents of these. Examples of lower alcohols include methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, and tertiary butanol. The mixing ratio of the lower alcohol in the mixed solvent is usually 60% by weight or more or 95% by weight or less, preferably 60 to 95% by weight. The amount of the solvent is usually 3 times by weight relative to the cellulose raw material. The upper limit is not particularly limited, but is 20 times by weight. Therefore, the amount of the solvent is preferably 3 to 20 times by weight. Mercerizing is usually carried out by mixing a hair base material and a mercerizing agent. As a mercerizing agent, alkali metal hydroxides, such as sodium hydroxide and potassium hydroxide, are mentioned, for example. The usage amount of the mercerizing agent is preferably 0.5 times mol or more, more preferably 1.0 times mol or more, and still more preferably 1.5 times mol or more, relative to the anhydrous glucose residue of the hair base material. The upper limit is usually 20 times mol or less, preferably 10 times mol or less, more preferably 5 times mol or less, therefore, preferably 0.5 to 20 times mol, more preferably 1.0 to 10 times mol, and More preferably, it is 1.5 to 5 times moles. The reaction temperature of the mercerization is usually 0°C or higher, preferably 10°C or higher. The upper limit is usually 70°C or lower, preferably 60°C or lower. Therefore, the reaction temperature is usually 0 to 70°C, preferably 10 to 60°C. The reaction time is usually 15 minutes or more, preferably 30 minutes or more. The upper limit is usually 8 hours or less, preferably 7 hours or less. Therefore, it is usually 15 minutes to 8 hours, preferably 30 minutes to 7 hours. The etherification reaction is usually performed by adding a carboxymethylating agent to the reaction system after mercerization. Examples of the carboxymethylating agent include sodium monochloroacetate. The amount of the carboxymethylating agent added is usually preferably 0.05 times mol or more, more preferably 0.5 times mol or more, and still more preferably 0.8 times mol or more with respect to the glucose residue in the cellulose raw material. The upper limit is usually 10.0 times mol or less, preferably 5 times mol or less, more preferably 3 times mol or less, therefore, preferably 0.05 to 10.0 times mol, more preferably 0.5 to 5 times mol, and More preferably, it is 0.8 to 3 times moles. The reaction temperature is usually 30°C or higher, preferably 40°C or higher, and the upper limit is usually 90°C or lower, preferably 80°C or lower. Therefore, the reaction temperature is usually 30 to 90°C, preferably 40 to 80°C. The reaction time is usually 30 minutes or more, preferably 1 hour or more. The upper limit is usually 10 hours or less, preferably 4 hours or less. Therefore, the reaction time is usually 30 minutes to 10 hours, preferably 1 hour to 4 hours. During the carboxymethylation reaction, the reaction solution can also be stirred as required. When the cellulose raw material is denatured by carboxymethylation, the degree of carboxymethyl substitution per unit of anhydrous glucose in the obtained carboxymethylated cellulose fibers is preferably 0.01 or more, more preferably 0.05 or more, and even more preferably is 0.10 or more. The upper limit is preferably 0.50 or less, more preferably 0.40 or less, and still more preferably 0.35 or less. Therefore, the carboxymethyl substitution degree is preferably 0.01 to 0.50, more preferably 0.05 to 0.40, and still more preferably 0.10 to 0.30. (1-3) Esterification In the present invention, any method may be used for the modification (esterification) of introducing phosphoric acid groups and phosphorous acid groups into cellulose fibers, and known methods can be used. Phosphate-esterified cellulose fibers with phosphoric acid groups and phosphite-esterified cellulose fibers with phosphorous acid groups are cellulose fibers obtained by esterification of compounds with phosphoric acid groups and phosphorous acid groups. Examples of compounds having a phosphoric acid group and a phosphorous acid group include phosphoric acid, polyphosphoric acid, phosphorous acid, phosphonic acid, polyphosphonic acid, and esters or salts thereof. These compounds are low cost and easy to handle. Specific examples of compounds having a phosphoric acid group and a phosphorous acid group include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, phosphoric acid Tripotassium, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, ammonium metaphosphate, phosphorous acid, sodium hydrogen phosphite, ammonium hydrogen phosphite, potassium hydrogen phosphite , Sodium dihydrogen phosphite, sodium phosphite, lithium phosphite, potassium phosphite, magnesium phosphite, calcium phosphite, triethyl phosphite, triphenyl phosphite, pyrophosphite, etc. Among them, phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, ammonium salt of phosphoric acid, phosphorous acid, sodium salt of phosphorous acid, potassium salt of phosphorous acid, phosphorous acid Ammonium salts of phosphoric acid are preferred; more preferred are sodium dihydrogen phosphate, disodium hydrogen phosphate, sodium hydrogen phosphite, and sodium dihydrogen phosphite. The compound which has a phosphoric acid group and a phosphorous acid group may be used individually by 1 type, and may be used in combination of 2 or more types. The esterification reaction is performed, for example, by reacting a cellulose raw material with a compound having a phosphoric acid group and a phosphorous acid group. The method of reacting a cellulose raw material with a compound having a phosphoric acid group and a phosphorous acid group includes, for example, a method of mixing a powder or an aqueous solution of a compound having a phosphoric acid group and a phosphorous acid group with a cellulose raw material, and a slurry of the cellulose raw material. A method of adding an aqueous solution of a compound having a phosphoric acid group and a phosphorous acid group. Among these, the method of mixing an aqueous solution of a compound having a phosphoric acid group or a phosphorous acid group with the cellulose raw material or its slurry is preferable because the uniformity of the reaction is improved and the esterification efficiency is increased. The pH of the aqueous solution of the compound having a phosphoric acid group and a phosphorous acid group is preferably 7 or less from the viewpoint of improving the introduction efficiency of the phosphoric acid group and the phosphorous acid group, and more preferably 3 to 7 from the viewpoint of suppressing hydrolysis. The lower limit of the amount of the compound having a phosphoric acid group and a phosphorous acid group added is preferably 0.2 part by weight or more, more preferably 1 part by weight or more, in terms of phosphorus atoms, relative to 100 parts by weight of the cellulose raw material. By making it into this range, the yield of the phosphated cellulose fiber and the phosphite cellulose fiber can be easily improved. On the other hand, the upper limit is preferably 500 parts by weight or less, more preferably 400 parts by weight or less. By making it into this range, the yield corresponding to the addition amount of the compound which has a phosphoric acid group and a phosphorous acid group can be obtained efficiently. When the cellulose raw material is reacted with a compound having a phosphoric acid group and a phosphorous acid group, a basic compound may be further added to the reaction system. The method of adding the basic compound to the reaction system includes, for example, a method of adding it to a slurry of a cellulose raw material, a method of adding it to an aqueous solution of a compound having a phosphoric acid group and a phosphorous acid group, or adding to a cellulose raw material and a phosphoric acid group , The method of the slurry of the compound of phosphite group. The basic compound is not particularly limited, but preferably a nitrogen-containing compound showing basicity. Furthermore, "showing basicity" generally means that the aqueous solution of the basic compound appears pink to red in the presence of the phenolphthalein indicator, or the pH of the aqueous solution of the basic compound is greater than 7. The nitrogen-containing compound showing basicity is not particularly limited as long as the effect of the present invention is exhibited. Among them, compounds having an amine group are particularly preferred. For example, urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine are mentioned. Among them, urea is particularly preferred for the reasons of low cost and easy operation. The addition amount of the basic compound is preferably 2 to 1000 parts by weight, more preferably 100 to 700 parts by weight. The reaction temperature is preferably 0 to 95°C, more preferably 30 to 90°C. The reaction time is not particularly limited, but is usually about 1 to 600 minutes, preferably 30 to 480 minutes. If the reaction conditions are within any of these ranges, excessive introduction of phosphoric acid groups and phosphorous acid groups into cellulose can prevent easy dissolution, and the yield of phosphoric acid esterified cellulose fibers and phosphorous acid esterified cellulose fibers can be easily improved. After reacting a compound having a phosphoric acid group and a phosphorous acid group with a cellulose raw material, a suspension is usually obtained. The suspension is dehydrated as required, and preferably heat treatment is performed after dehydration. Thereby, the hydrolysis of the cellulose raw material can be suppressed. The heating temperature is preferably 100 to 170°C, and the period included in the heat treatment is more preferably 130°C or lower (and more preferably 110°C or lower), and after removing water, it is heated at 100 to 170°C. Phosphate cellulose fibers and phosphite cellulose fibers are preferably subjected to washing treatment such as washing with cold water after boiling. Among the phosphated cellulose fibers and the phosphite cellulose fibers, the anionic groups (phosphoric acid groups and phosphorous acid groups) contained in the phosphated cellulose fibers and the phosphite cellulose fibers are preferably 0.1 to 0.1 3.5mmol/g. (1-4) Sulfonated sulfonated cellulose fibers are cellulose fibers obtained by sulfonating a compound having a sulfuric acid group. Examples of compounds having a sulfuric acid group include sulfuric acid, sulfamic acid, chlorosulfonic acid, sulfur trioxide, and esters or salts thereof. These compounds are low cost and easy to handle. In the present invention, sulfamic acid is preferably used. Compared with sulfuric anhydride or sulfuric acid aqueous solution, amine sulfonic acid not only has low solubility of cellulose, but also has low acidity, so it can maintain the degree of polymerization. In addition, there is no restriction on the operation of sulfuric anhydride or sulfuric acid aqueous solution that is highly acidic and highly corrosive, and it is not designated as a specific substance under the Air Pollution Prevention Act, so the load on the environment is small. The amount of sulfamic acid to be used can be appropriately adjusted in consideration of the amount of anionic group (sulfuric acid group) introduced into the cellulose fiber. The sulfamic acid is preferably used in an amount of 0.01 to 50 moles, more preferably 0.1 to 30 moles, per 1 mole of the glucose unit in the cellulose molecule, for example. (2) Support of cellulose fibers by metal ions and/or metal particles In the present invention, the cellulose fibers containing anionic groups, especially carboxyl groups or carboxylate groups, further contain Ag, Au, Pt, Metal ions and/or metal particles of one or more metal elements in the group of Pd, Ni, Mn, Fe, Ti, Al, Zn, and Cu exhibit excellent antiviral, deodorant, and antibacterial functions. Among them, by using one or more ions selected from the group of Ag and Cu, the antiviral, deodorizing, and antibacterial functions are further improved, which is preferable. Cellulose fibers with anionic groups, since metal ions or metal particles are chemically bound to the cellulose fibers, when contained in the sheet, the metal component is not easily detached from the sheet, and the mechanical properties such as tensile strength are also good. It has the characteristics of no reduction in performance and strength. The method for supporting the above-mentioned metal ions on the above-mentioned cellulose fibers is not particularly limited. For example, a pre-prepared dispersion liquid of cellulose fibers can be mixed with an aqueous solution of a metal compound, or a dispersion liquid containing cellulose fibers can be coated on the base. A metal compound aqueous solution was dropped and impregnated on the film to form a film. At this time, the film may be maintained in a state of being fixed to the base material or peeled from the base material. Although the detailed mechanism is unknown, it is presumed that the metal ion derived from the metal compound undergoes ion exchange with the sodium ion that has been ionically bonded to an anion group such as a carboxylate group by such a method to form it. Ionic bonds or coordination to attach metal ions to cellulose fibers. This pair of ion exchange is considered to be caused by the difference in the ionization tendency of the metal ions. Here, the metal compound aqueous solution refers to an aqueous solution of a metal salt. Examples of metal salts include complexes (zirconium ions), halides, nitrates, sulfates, and acetates. The concentration of the metal compound aqueous solution is not particularly limited, but is preferably 0.2 to 2.2 mmol, more preferably 0.4 to 1.8 mmol, relative to 1 g of cellulose fibers. The time during which the metal compound is brought into contact can be appropriately adjusted. The temperature at the time of bringing the metal compound into contact is not particularly limited, but it is preferably in the range of 2 to 50°C. In addition, the pH of the liquid at the time of contact is not particularly limited, but when the pH is low, metal ions are less likely to bond to the carboxyl group, so it is preferably in the range of 7 to 13, and particularly preferably in the range of pH 8 to 12. In the present invention, as described above, the effect is exerted by introducing metal ions into cellulose fibers, but a part of the metal ions may be reduced to become metal particles in some cases. Further, if necessary, metal particles may be partially formed on the surface of the cellulose fibers by reducing a part of the metal ions bound to the obtained metal ion-containing cellulose fibers by adding a reducing agent or the like. However, it is preferable from the viewpoint of antiviral, antibacterial, and deodorizing functions to use the total amount of the metal compound as it is in the form of metal ions without performing special reduction treatment. Although the mechanism by which metal particles are generated in the cellulose fibers by reducing the metal compound in the metal-containing cellulose fibers obtained above is not clear, it is presumed as follows. By the reduction reaction, the metal compound in the metal compound-containing cellulose fiber or the ion system derived from the metal compound is reduced to become a metal. At this time, the generated metal is supported on the surface of the cellulose fiber. Likewise, the generated adjacent metals are integrated with each other, thereby forming particles. On the other hand, although present in the vicinity of the cellulose fibers, metal compounds and the like that are not bound to the cellulose fibers are also reduced to generate metals. The metal system is rapidly integrated with the metal on the surface of the cellulose fiber to form metal particles. The reduction reaction can be carried out by a known method, and is preferably carried out so as to reduce the metal compound without breaking the bonds between the metal compound and the cellulose fibers. Examples of such a reduction method include a gas-phase reduction method using hydrogen and a liquid-phase reduction method using a reducing agent such as an aqueous sodium borohydride solution. Conditions such as time and temperature in the gas-phase reduction are appropriately adjusted, for example, the reaction may be carried out at 50 to 60° C. for about 1 to 3 hours. The gas-phase reduction reaction is preferably performed in a state in which the oxidized cellulose fibers do not contain water or a solvent. During the reduction reaction, the film may be maintained fixed to the substrate or may be in a state of being peeled off from the substrate. In the case of liquid-phase reduction, a film can be obtained from the above-mentioned dispersion liquid, and the reduction reaction can be carried out after drying or not drying the film. Moreover, a liquid-phase reduction reaction may be performed without drying a dispersion liquid. The reaction temperature in the liquid phase reduction is preferably 4 to 40°C, more preferably room temperature. The average particle size of the metal particles can be obtained from transmission electron microscope images or X-ray diffraction. In the present invention, when the average particle diameter of the metal particles is determined from a transmission electron microscope image, it is preferably in the range of 1 to 50 nm. Specifically, as a method of obtaining the average particle diameter from a transmission electron microscope image, a transmission electron microscope image of a cellulose fiber is prepared, and the equivalent circle diameter of a primary particle of a plurality of metal particles is obtained from the image. , which is obtained by averaging these values. Cellulose fibers contain metal ions and/or metal particles, which can be confirmed by scanning electron microscopy and ICP emission spectroscopic analysis of a liquid extracted with a strong acid. In other words, the presence of metal ions was not confirmed in the scanning electron microscope image, but the metal was confirmed to be contained in the ICP emission spectroscopic analysis. On the other hand, for example, when the above-mentioned metal is reduced by an ion and exists as a metal particle, since the metal particle can be confirmed by a scanning electron microscope image, the presence or absence of a metal ion can be determined. In addition, the presence or absence of metal ions can also be determined by scanning electron microscope images and element mapping. In other words, metal ions cannot be confirmed by scanning electron microscope images, but the presence of metal ions can be confirmed by performing element distribution. In the aforementioned step of supporting metal ions or metal particles, the content of the aforementioned metal ions and/or metal particles relative to the cellulose fibers is preferably in the range of 10-100 mg/g, more preferably 15-80 mg/g. The range, particularly preferably, is the range of 20 to 60 mg/g. When the total amount is less than 10 mg/g, the antiviral, deodorizing, and antibacterial functions may be poor. On the other hand, if the total exceeds 100 mg/g, the metal ions may be easily eluted during production, and the load of the wastewater treatment may increase. (3) Beating The cellulose fibers in the present invention may be beaten at least once from before the aforementioned modification treatment to after the aforementioned metal support treatment. Here, the beating treatment refers to a treatment for imparting mechanical shearing force to fibers. By the beating treatment, a part of the cellulose fiber is fibrillated, and the surface area is increased, whereby the bonding between fibers during drying can generally be enhanced. The beating treatment can further improve the antiviral, deodorizing and antibacterial effects after the metal ions and/or metal particles are supported. On the other hand, if the beating process is carried out too much and the cellulose fibers are excessively fined, the yield decreases when the cellulose fibers are blended with the pulp to make paper, or the cellulose fibers are not retained (do not remain) in the paper, and the antiviral, deodorizing, and antibacterial functions lower, so not good. The index of beating degree can use Canadian Standard Freeness (CSF). Specifically, when the freeness (CSF) is less than 30ml, the antiviral, deodorizing, and antibacterial functions are reduced due to the decrease in the yield of the sheet. When the freeness (CSF) exceeds 600ml, the fibrosis is insufficient, and the antiviral , deodorant, antibacterial function is reduced. In this way, the antiviral, deodorizing, and antibacterial functions can be improved by setting the freeness (CSF) of the cellulose fibers to 30 to 600 ml. Water was added to the obtained oxidized cellulose fibers to obtain a dispersion liquid having a solid content concentration of 2%, and the pH was adjusted to 9.0. Next, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring so that the concentration relative to 1 g of the oxidized cellulose fibers was 1.0 mmol/g, and the mixture was further stirred for 30 minutes, thereby allowing the oxidized cellulose fibers to contain Cu ions. Then, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-supported oxidized cellulose fibers (solid content: 30 mass %) impregnated with water. The content of metal ions in the obtained oxidized cellulose fibers carrying Cu ions was 43.8 mg/g, and the Canadian Standard Freeness (CSF) of the oxidized cellulose fibers carrying Cu ions was 500 ml. 1-2. Production of antiviral sheet A sheet sample was produced as follows. (1) Sheet 1 (Sample 1-1) As cellulose fibers, deinked recycled pulp from newspaper recycled paper (manufactured by Nippon Paper Co., Ltd., CSF: 300 ml) was used, and the carrier produced in Experiment 1 was blended with it. The oxidized cellulose fibers of Cu ions were adjusted to 1% by weight with respect to the entire cellulose fibers. Using a Three-One Motor®, stirring at 500 rpm, 30% by weight (solid content) of light calcium carbonate, 0.7% by weight (solid content) of polyaluminum chloride, and 100% by weight of cellulose fibers were added in this order. 0.05% by weight (solid content) of a paper strength enhancer to prepare pulp slurry. From the obtained pulp slurry, a sheet having a weight per square meter of 60 g/m 2 , a paper thickness of 120 μm and an ash content of 14% was produced using a circular hand paper machine. (2) Sheet 2 (Sample 1-2) A gelatinizing liquid containing 5% by weight of oxidized starch (manufactured by Corn Starch, Japan, SK20) was produced. The sizing press liquid was applied to both sides of the sheet 1 and dried by a conventional method (coating amount: 1 g/m 2 in total on both sides). (3) Sheet 3 (Sample 1-3) On one side of Sheet 2, using an RI-I type printing machine (manufactured by Ishikawajima Industrial Machinery Co., Ltd.), the Vantean Eco ink was applied so that the ink density immediately after printing was 1.0. (manufactured by Toyo Ink Co., Ltd.) for solid printing on the entire surface. (4) Sheet 4 (Sample 1-4) A sheet was produced in the same manner as Sheet 1, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 3% by weight with respect to the entire cellulose fibers . (5) Sheet 5 (Sample 1-5) A sheet was produced in the same manner as Sheet 1, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 5% by weight relative to the entire cellulose fibers . (6) Sheet 6 (Sample 1-6) A sheet was produced in the same manner as Sheet 2, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 5% by weight relative to the entire cellulose fibers . (7) Sheet 7 (Samples 1-7) A sheet was produced in the same manner as Sheet 3, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 5% by weight relative to the entire cellulose fibers . (8) Sheet 8 (Sample 1-8) As cellulose fibers, LBKP (manufactured by Nippon Paper Co., Ltd., CSF: 480 ml) was used, and the oxidized cellulose fibers carrying Cu ions produced in Experiment 1 were blended, It was 4 weight% with respect to the whole cellulose fiber. With respect to 100% by weight of cellulose fibers, 0.16% by weight of sizing agent, 1.50% by weight of aluminum sulfate, and 0.70% by weight of cationized starch were sequentially added to prepare pulp slurry. From the obtained pulp slurry, paper was made using a paper machine at a speed of 250 m/min, and calendering was performed to produce a sheet having a weight per square meter of 71.0 g/m 2 and a paper thickness of 105 μm. (9) Sheet 9 (Samples 1-9) A sheet was produced in the same manner as Sheet 8, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 7% by weight with respect to the entire cellulose fibers . (10) Sheet 10 (Sample 1-10) A sheet was produced in the same manner as Sheet 8, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 10% by weight with respect to the entire cellulose fibers . (11) Sheet 11 (Sample 1-11, Comparative Example) A sheet was produced in the same manner as Sheet 1, except that the oxidized cellulose fibers carrying Cu ions were not used. (12) Sheet 12 (Samples 1-12, Comparative Example) A sheet was produced in the same manner as Sheet 8, except that the oxidized cellulose fibers carrying Cu ions were not used. (13) Sheet 13 (Samples 1-13, Comparative Example) The same procedure as Sheet 8 was carried out, except that oxidized cellulose fibers carrying Cu ions were blended so as to be 1% by weight with respect to the entire cellulose fibers to manufacture flakes. 3-3. Evaluation of antiviral sheet With respect to the obtained antiviral sheet, the antiviral function and the like were evaluated by the method shown below. [Content of copper] The content (mg/g) of metal ions and metal particles per 1 g of the sheet was measured by ICP optical emission spectrometry (ICP-OES) by the following procedure. (1) The sample for measurement was pre-dried (50°C, 1 day) before measurement. (2) Weigh 0.1 g of the dried sample for measurement, and put it into a beaker with a volume of 50 mL. (3) 10 ml of concentrated nitric acid was taken with a full pipette, and added to a beaker containing a measurement sample to prepare a measurement sample solution (10-fold dilution). (4) After standing for 30 minutes, the fiber component was removed (filtered) from the measurement sample liquid through a syringe filter. (5) Take 1 ml of the filtered measurement sample solution with a micropipette and add it to a test tube containing 49 ml of distilled water (50-fold dilution). (6) Close the lid of the test tube tightly and stir with vibration. (7) The content of metal ions and metal particles was measured (quantitatively) using ICP-OES (manufactured by Agilent Technology, ICP-OES 5110). (8) From the quantitative results (ppb) by ICP-OES, the content (mg/g) of metal ions and metal particles per 1 g of flakes was calculated based on the following formula. (Quantitative result of ICP-OES (ppb)×10×50)/(Weight of sample for measurement (g))×1000/1000000000 , and the antiviral activity value (Mv) was calculated. The weight of the sheet to be tested was 0.4 g, and the following two types of test viruses were used. ･Influenza virus (H3N2, ATCC VR-1679) ･Cat calicivirus (Strain: F-9 ATCC VR-782) [Deodorizing function] Deodorizing function test, based on SEK mark fiber product certification standard (JEC301) , Fiber Evaluation Technology Council) method, with ammonia as the object, the test data size 100cm 2 to implement. The deodorizing function was evaluated by the following criteria. ◎(Very good): Reduction rate of ammonia is 80% or more ○(Good): Reduction rate of ammonia is 70% or more and less than 80% ×(Bad): Reduction rate of ammonia is less than 70% [Antibacterial function] According to JIS L1902 "Antibacterial test method and antibacterial effect of fiber products", qualitative test was carried out by halo test. Specifically, an agar culture medium containing coliform was prepared, a 5 cm x 5 cm test piece of antiviral sheet was placed thereon, and after culturing at 37°C for 17 hours, it was confirmed whether there was a "growth inhibition zone" of the test bacteria around the sample. ". The antibacterial function was evaluated by the following criteria. ○: Growth inhibition zone is observed, and antibacterial function is present. ×: No growth inhibition zone was observed, and no antibacterial function was found. As apparent from the above results, according to the present invention, an antiviral sheet having excellent antiviral function, deodorizing function, and antibacterial function can be produced. Experiment 2 2-1 Production of Cellulose Fiber Containing Metal Ions (1) Cellulose Fiber 1 5.00 g (absolute dry weight) of bleached unbeaten kraft pulp (whiteness 85%) from conifers was added to dissolve 39 mg of TEMPO (Sigma Aldrich) (0.05 mmol relative to 1 g of absolute dry weight of cellulose) and 514 mg of sodium bromide (1.0 mmol relative to 1 g of absolute dry weight of cellulose) in an aqueous solution of 500 ml, stirred until the pulp is evenly dispersed. Next, an aqueous sodium hypochlorite solution was added to the reaction system so that the sodium hypochlorite ratio was 5.5 mmol/g, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, and 3M aqueous sodium hydroxide solution was added successively to adjust the pH to 10. The reaction was terminated at the time point when sodium hypochlorite was consumed and the pH in the system no longer changed (the time required for the oxidation reaction: about 90 minutes). The reacted mixture was filtered with a glass filter, washed twice with a sufficient amount of water, and filtered to obtain oxidized cellulose fibers (solid content: 10% by mass, pulp yield: 90%, carboxyl group) impregnated with water. Amount: 1.68 mmol/g). Water was added to the obtained oxidized cellulose fibers to obtain a dispersion liquid having a solid content concentration of 2%, and the pH was adjusted to 9.0. Next, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added with stirring so that the concentration of the oxidized cellulose-based fibers would be 1.0 mmol/g with respect to 1 g of the oxidized cellulose-based fibers, and further stirred for 30 minutes, thereby making the oxidized cellulose-based fibers Contains Cu ions. Then, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-carrying cellulose fibers (solid content: 30 mass %) impregnated with water. The content of metal ions in the obtained metal ion-containing cellulosic fibers was 40 mg/g, and the freeness of the metal ion-containing cellulosic fibers was 500 ml. (2) Cellulose fiber 2 In a mixer that can mix pulp, add 200 g of bleached coniferous kraft pulp (NBKP, made by Nippon Paper) on a dry mass basis and 111 g on a dry mass basis of sodium hydroxide, so that the pulp solid content becomes 20% (w/ v) by adding water. Then, after stirring for 30 minutes at 30 degreeC, 216 g of sodium monochloroacetate (in terms of active ingredient) was added. After stirring for 30 minutes, the temperature was raised to 70°C, and the mixture was stirred for 1 hour. Then, the reactant was taken out, neutralized and washed to obtain a carboxymethylated cellulose-based fiber (carboxymethyl substitution degree per glucose unit: 0.25). The pH of the carboxymethylated cellulose-based fiber (CM-based cellulose-based fiber) dispersion obtained by the above operation was adjusted to 8.5 so that the concentration would be 1.0 mmol/g (per 1 g of the CM-based cellulose-based fiber). , add CuCl 2 aqueous solution, and stir for 15 min. In this way, the CMized cellulose-based fibers are made to contain Cu ions, and unreacted metal salts are removed by washing to obtain Cu ion-supported cellulose-based fibers (metal ion-containing cellulose-based fibers). The content of the metal ion (Cu) was 31.3 mg/g with respect to the obtained metal ion-containing cellulose-based fiber. (3) Cellulose fiber 3 6.75 g of sodium dihydrogen phosphate dihydrate and 4.83 g of disodium hydrogen phosphate were dissolved in 19.62 g of water to obtain a reaction solution. Water was added to bleached unbeaten kraft pulp (85% whiteness) from conifers to make the consistency 4%. Then, using a double-disc refiner, it was beaten until the CSF became 200 ml and the length average fiber length became 0.7 mm. The cellulose suspension thus obtained was diluted to 0.3% to obtain a pulp sheet having a moisture content of 90% and a solid content (absolute dry mass) of 3 g. This pulp sheet was immersed in 31.2 g of the above-mentioned reaction solution, heated in a blow dryer at 105° C. for 1 hour, and further heat-treated at 150° C. for 1 hour to introduce phosphoric acid groups into the cellulose fibers. Next, 500 ml of ion-exchanged water was added to the pulp sheet into which the phosphoric acid group was introduced into the cellulose fibers, and after stirring and washing, dehydration was performed. The dehydrated sheet was diluted with 300 ml of ion-exchanged water, and while stirring, 5 ml of a 1N aqueous sodium hydroxide solution was added little by little to obtain a cellulose suspension having a pH of 12 to 13. After that, the cellulose suspension was dehydrated, and 500 ml of ion-exchanged water was added for washing. Moreover, by infrared absorption spectrum measurement by FT-IR, it was found that the absorption derived from the phosphoric acid group was observed at 1230 to 1290 cm −1 , and the addition of the phosphoric acid group was confirmed. The introduction amount of the phosphoric acid group at this time was 2.1 mmol/g per 1 g (mass) of the fine fibrous cellulose. Water was added to the above-mentioned phosphated cellulose-based fibers to obtain a dispersion liquid with a solid content concentration of 2%, and the pH was adjusted to 9.0, so that the concentration was 1.0 mmol/g with respect to 1 g of the phosphated-esterified cellulose-based fibers. In this manner, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring, and the mixture was further stirred for 30 minutes, thereby allowing the phosphated cellulose-based fibers to contain Cu ions. For this, washing with sufficient water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-supported cellulose fibers (metal ion-containing cellulose fibers impregnated with water at a solid content of 30% by mass). of cellulose fibers). The content of metal ions was 41 mg/g relative to the phosphated cellulose fibers. (4) Cellulose fiber 4 A reaction solution was prepared by mixing 13 g of sodium hydrogen phosphite and pentahydrate, 10.8 g of urea, and 76.2 g of water. 100 g of the reaction solution was mixed with 10 g of dry weight of bleached unbeaten kraft pulp (whiteness 85%) derived from conifers, and dried at 105°C. The dried pulp was reacted at 170° C. for 2 hours, and the water washing and filtration were repeated twice to obtain a phosphite cellulose-based fiber containing a cation formed from an inorganic substance and a phosphorous acid-introduced ester. The introduction amount of the phosphite group was 1.2 mmol/g per 1 g (mass) of the fine fibrous cellulose. Water was added to the above-mentioned phosphite cellulose fibers to obtain a dispersion liquid with a solid content concentration of 2%, and the pH was adjusted to 9.0 to obtain a concentration of 1.0 mmol/ 1 g of the phosphite cellulose fibers. In the manner of g, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring, and the mixture was further stirred for 30 minutes, thereby allowing the phosphite cellulose fibers to contain Cu ions. Thereafter, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-supported cellulose fibers impregnated with water with a solid content of 30% by mass (metal ion-containing cellulose fibers). cellulose fibers). The content of metal ions was 42 mg/g with respect to the phosphite cellulose fibers. (5) Cellulose fiber 5 20 g of sulfamic acid, 10 g of urea, and 100 ml of water were mixed to prepare a reaction solution. To 130 g of the reaction solution, 2 g (dry weight) of bleached unbeaten kraft pulp (whiteness 85%) derived from conifers was added, and the prepared slurry was stirred for 10 minutes. After stirring, the slurry was suction-filtered using filter paper to prepare a pulp sheet. The pulp sheet was placed in a dryer set at 50°C, and dried until the moisture content became an equilibrium state. The dried pulp was heated at 120°C for 30 minutes. After the heating reaction, the reacted pulp was washed with pure water until it became neutral, and a sulfonated cellulose-based fiber treated with sulfamic acid/urea was prepared. The introduction amount of the base at this time was 0.9 mmol/g. Water was added to the above-mentioned sulfonated cellulose fibers to obtain a dispersion having a solid content concentration of 2%, and the pH was adjusted to 9.0, so that the concentration was 0.5 mmol/g with respect to 1 g of the sulfonated cellulose fibers, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring, and the mixture was further stirred for 30 minutes, whereby the sulfonated cellulose fibers contained Cu ions. Next, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-supporting cellulose fibers (metal ion-containing fibers) impregnated with water with a solid content of 30% by mass. cellulose fibers). The content of metal ions was 21 mg/g relative to the sulfonated cellulose fibers. 2-2. Manufacture of antiviral sheet from hardwood bleached kraft pulp (freeness) containing 5% of metal ion-containing cellulosic fibers as a metal ion-free cellulosic fiber (general cellulosic fiber). 600 ml of LBKP (manufactured by Nippon Paper Co., Ltd.) 95% was further added with water to prepare an aqueous dispersion with a solid content concentration of 0.5% by mass. It was paper-made with a circular hand paper machine so that the weight per square meter was 30 g/m 2 , dewatered with a pressing device, and further dried at 85° C. with a drum dryer to produce a paper with a diameter of about 16 cm. Round antiviral sheet. In addition, as a comparative example, a hardwood bleached kraft pulp (LBKP with a freeness of 600 ml; Nippon Paper Co., Ltd.) which is a cellulose-based fiber containing no metal ions is blended without blending the metal-containing cellulose-based fiber. A thin sheet (Sample 2-6) was produced in the same manner as above except that the ratio was 100%. 2-3. Evaluation of antiviral sheet For the obtained sheet samples, the antiviral properties were evaluated in the same manner as in Experiment 1. As apparent from the above results, the sheet of the present invention containing the metal-containing cellulose fibers exhibits high antiviral properties. On the other hand, a sheet that does not contain metal-containing cellulose fibers has low antiviral properties. Experiment 3 3-1. Production of Cellulose Fiber Containing Metal Ions 5.00 g (absolute dry weight) of bleached unbeaten kraft pulp (whiteness 85%) from conifers was added to dissolved TEMPO (Sigma Aldrich Company) 39 mg (0.05 mmol relative to 1 g of absolute dry weight of cellulose) and 514 mg of sodium bromide (1.0 mmol relative to 1 g of absolute dry weight of cellulose) aqueous solution, stir until the pulp is uniformly dispersed. Next, an aqueous sodium hypochlorite solution was added to the reaction system so that sodium hypochlorite was adjusted to 5.5 mmol/g, and an oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, and 3M aqueous sodium hydroxide solution was added successively to adjust the pH to 10. The reaction was terminated at the time point when sodium hypochlorite was consumed and the pH in the system no longer changed (the time required for the oxidation reaction: 90 minutes). The reacted mixture was filtered with a glass filter, washed twice with a sufficient amount of water, and filtered to obtain oxidized cellulose fibers (solid content: 10% by mass, pulp yield: 90%, carboxyl group content) impregnated with water. 1.68 mmol/g). Water was added to the obtained oxidized cellulose fibers to obtain a dispersion liquid having a solid content concentration of 2%, and the pH was adjusted to 9.0. Next, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring so as to have a concentration of 1.6 mmol/g with respect to 1 g of the oxidized cellulose fibers, and further stirred for 30 minutes, so that the oxidized cellulose fibers contained Cu ion. Then, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-carrying cellulose fibers (solid content: 30 mass %) impregnated with water. The content of metal ions in the obtained metal ion-containing cellulosic fibers was 40 mg/g, and the freeness of the metal ion-containing cellulosic fibers was 500 ml. 3-2. Production of non-woven fabrics Conifer bleached kraft pulp (NBKP with a freeness of 600ml) is blended with 10% of the above-mentioned metal ion-containing cellulosic fibers, as the metal ion-free cellulosic fibers (general cellulosic fibers); Nippon Paper Co., Ltd.) 20%, PET fiber (Teijin Frontier Co., Ltd., Ecopet) as a synthetic fiber cut into 5mm fiber length 30%, adhesive fiber (core-sheath type polyester composite fiber, melting point of sheath part: 100~ 160°C, core part: polyethylene terephthalate) 40%, and water was added thereto to prepare an aqueous dispersion having a solid content concentration of 0.5% by mass. It was paper-made with a circular hand paper machine so that the weight per square meter was 30 g/m 2 , dewatered with a pressing device, and further dried at 85° C. with a drum dryer to produce a paper with a diameter of about 16 cm. Round non-woven fabric (Sample 3-1). In addition, as a comparative example, in the step of producing a nonwoven fabric, a cellulose fiber containing no metal ions (NBKP pulp with a freeness of 600 ml, manufactured by Nippon Paper) was blended without blending metal ions. A nonwoven fabric (Sample 3-2) was produced in the same manner as above except that the ratio was 30%. 3-3. Evaluation of Nonwoven Fabric The antiviral properties were evaluated in the same manner as in Experiment 1 with respect to the obtained nonwoven fabric. As apparent from the above results, the nonwoven fabric containing metal-containing cellulose fibers and synthetic fibers exhibits high antiviral properties. On the other hand, the nonwoven fabric containing no metal-containing cellulosic fibers did not exhibit antiviral properties. Experiment 4 4-1. Production of oxidized cellulose fibers carrying Cu ions Bleached unbeaten kraft pulp (85% whiteness) 275BDkg (absolute dry weight) from conifers was added to dissolved TEMPO (Sigma Aldrich Company) 1.07kg (0.25 mmol relative to 1 g of absolute dry weight of cellulose) and 500 ml of an aqueous solution of 28.3 kg of sodium bromide (1.0 mmol relative to 1 g of absolute dry weight of cellulose), stir until pulp Evenly dispersed. Next, an aqueous sodium hypochlorite solution was added to the reaction system so that the sodium hypochlorite ratio was 5.2 mmol/g, and the oxidation reaction was started at room temperature. During the reaction, the pH in the system decreased, and 3M aqueous sodium hydroxide solution was added successively to adjust the pH to 10. The reaction was terminated at the time point when sodium hypochlorite was consumed and the pH in the system no longer changed (the time required for the oxidation reaction: about 90 minutes). The reacted mixture was dehydrated with a screw press, washed twice with a sufficient amount of water, and filtered to obtain oxidized cellulose fibers impregnated with water (solid content: 10% by mass, pulp yield: 90%, Amount of carboxyl groups: 1.68 mmol/g). Water was added to the obtained oxidized cellulose fibers to obtain a dispersion liquid having a solid content concentration of 2%, and the pH was adjusted to 9.0. Next, CuCl 2 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added while stirring so as to have a concentration of 1.0 mmol/g with respect to 1 g of the oxidized cellulose fibers, and further stirred for 30 minutes, so that the oxidized cellulose fibers contained Cu ions . Then, washing with a sufficient amount of water and filtration were repeated twice to remove unreacted metal salts to obtain Cu ion-supported oxidized cellulose fibers (solid content: 30 mass %) impregnated with water. The content of metal ions in the obtained oxidized cellulose fibers carrying Cu ions was 43.8 mg/g, and the Canadian Standard Freeness (CSF) of the oxidized cellulose fibers carrying Cu ions was 500 ml. 4-2. Production of antiviral sheet (1) Sample 4-1 LBKP (manufactured by Nippon Paper, CSF: 470 ml) was used as the cellulose fiber, and oxidized cellulose fibers carrying Cu ions were blended therein so that It is 6 weight% with respect to the whole cellulose fiber. Light calcium carbonate was added in it to make the ash in the paper 5%. A pulp slurry was prepared by adding 0.80% by weight of cationized starch to 100% by weight of cellulose fibers. From the obtained pulp slurry, papermaking was performed at a speed of 540 m/min using a paper machine. With respect to 100 parts by weight of oxidized starch (manufactured by Corn Starch, Japan, SK20), 3.5 parts by weight of raw salt was added to prepare a surface treatment liquid adjusted to a solid content concentration of 11% by mass, and applied using a gate roll coater (GRC) (Coating amount on both sides: about 1.6 g/m 2 ). After drying, calendering treatment was performed to obtain paper with a weight of about 80 g/m 2 per square meter. (2) Sample 4-2 LBKP (manufactured by Nippon Paper, CSF: 470 ml) was used as the cellulose fiber system, and oxidized cellulose fibers carrying Cu ions were blended therein so that the total cellulose fibers were 3 % by weight (light calcium carbonate without blending). A pulp slurry was prepared by adding 0.80% by weight of cationized starch to 100% by weight of cellulose fibers. From the obtained pulp slurry, papermaking was performed at a speed of 540 m/min using a paper machine. With respect to 100 parts by weight of oxidized starch (manufactured by Corn Starch, Japan, SK20), 5.6 parts of anionic sizing agent (Harima Kasei) and 3.5 parts by weight of raw salt were added to prepare a surface treatment liquid adjusted to a solid content concentration of 11% by mass, Coating was performed using a guillotine coater (GRC) (coating amount on both sides: about 1.6 g/m 2 ). After drying, calendering treatment was performed to obtain paper with a weight of about 80 g/m 2 per square meter. (3) Sample 4-3 The paper was prepared in the same manner as in Sample 4-2, except that talc was added to make the ash content in the paper 5%. (4) Sample 4-4 was mixed so that LBKP (manufactured by Nippon Paper, CSF: 480 ml): NBKP (manufactured by Nippon Paper, CSF: 590 ml) = 72:24, as cellulose fibers, in which Cu was blended and supported The ion-oxidized cellulose fiber is 4% by weight with respect to the entire cellulose fiber. To 100% by weight of cellulose fibers, 0.16% by weight of sizing agent, 1.50% by weight of aluminum sulfate (aluminum sulfate), and 0.70% by weight of cationized starch were sequentially added to prepare pulp slurry. From the obtained pulp slurry, papermaking was performed using a paper machine at a speed of 250 m/min, and calendering was performed to produce a sheet (weight per square meter: 71.0 g/m 2 , paper thickness: 105 μm). (5) Sample 4-5 LBKP (manufactured by Nippon Paper, CSF: 470 ml) was used as the cellulose fiber system, and oxidized cellulose fibers carrying Cu ions were blended therein so that the total cellulose fibers were 3 weight%. Light calcium carbonate was added in it to make the ash in the paper 10%. A pulp slurry was prepared by adding 0.80% by weight of cationized starch to 100% by weight of cellulose fibers. From the obtained pulp slurry, papermaking was performed at a speed of 540 m/min using a paper machine. With respect to 100 parts by mass of oxidized starch (manufactured by Corn Starch, Japan, SK20), 1.4 parts by mass of anionic sizing agent (Harima Kasei) and 3.5 parts by mass of raw salt were added to prepare a surface treatment liquid adjusted to a solid content concentration of 11 mass %, Coating was performed using a guillotine coater (GRC) (coating amount on both sides: about 1.6 g/m 2 ). After drying, calendering treatment was performed to obtain paper with a weight of about 80 g/m 2 per square meter. 4-3. Evaluation of antiviral properties About the obtained sheet, the antiviral function and the like were evaluated in the same manner as in Experiment 1. In addition, the metal elution amount etc. were evaluated as follows. [Weight per square meter] It was measured according to JIS P8124. [Paper Thickness] Measured according to JIS P8118. [ISO whiteness] According to JIS P8148, it measured using a color difference meter (Murakami color, CMS-35SPX). [ISO Opacity] Measured according to JIS P8149. [Hue] Measured according to JIS P8150. [Stokes sizing degree] It measured according to JIS P8122. [Pen writing sizing] Measured according to J.TAPPI No.12. [pH on paper surface] A non-glass electrode for surface measurement (manufactured by HORIBA, flat-type pH composite electrode 6261-10C) was attached to a pH meter (manufactured by HORIBA, model F-24), and the measurement was carried out according to the following procedure. (1) Wash the electrode with pure water. (2) Add 1 drop of pure water to the tip of the electrode. (3) Connect the electrode tip to the surface of the measurement sample, and evaluate the value after 1 minute. (4) Repeat (1) to (3) 5 times, and record the average value as the pH of the paper. [Metal eluted amount] For copper and aluminum, the eluted amount of metal ions and metal particles per 0.8 g of sheet in 100 ml of ultrapure water was measured by ICP-OES (ICP-OES). (1) The sample for measurement was pre-dried (50°C, 1 day) before measurement. (2) Put ultrapure water (30°C, 100ml) in a 300mL volume cup. (3) Put 0.8 g of the dried measurement sample into the cup of (2) and cover it. (4) After standing at 30° C. for 30 minutes, the fiber component was removed (filtered) from the measurement sample liquid through a syringe filter. (5) Put 49ml of the filtered measurement sample solution into the test tube, and add 1ml of concentrated nitric acid with a micropipette. (6) Close the lid of the test tube tightly and stir with vibration. (7) The content of metal ions and metal particles was measured (quantitatively) using ICP-OES (manufactured by Agilent Technology, ICP-OES 5110). (8) From the quantitative results by ICP-OES, the elution amount of metal ions and metal particles per 0.8 g of flakes in 100 ml of ultrapure water was calculated based on the following formula. Quantitative result of ICP-OES (ppb)×50/49 [Deodorizing function] Deodorizing function test is based on the method of SEK mark fiber product certification standard (JEC301, Fiber Evaluation Technology Council), and the object is hydrogen sulfide , with a test data size of 100cm 2 to implement. The deodorizing function was evaluated by the following criteria. ◎(Very good): The reduction rate of hydrogen sulfide is 80% or more. ○(Good): The reduction rate of hydrogen sulfide is 70% or more and less than 80%. ×(Bad): The reduction rate of hydrogen sulfide is less than 70%. [ Antibacterial function] According to JIS L1902 "Antibacterial test method and antibacterial effect of fiber products", qualitative test was carried out by halo method. Specifically, an agar culture medium containing Escherichia coli and Staphylococcus aureus was prepared, a 5 cm x 5 cm test piece with an antiviral sheet was placed thereon, and after culturing at 37° C. for 17 hours, it was checked whether there was a “test bacteria” around the sample. growth inhibition zone". The antibacterial function was evaluated by the following criteria. ○: Growth inhibition zone is observed, and antibacterial function is present. ×: No growth inhibition zone was observed, and no antibacterial function was found. As apparent from the above results, according to the present invention, an antiviral sheet having excellent antiviral function, deodorizing function, and antibacterial function can be produced.
