液晶配向膜係藉由在基板上塗佈液晶性組合物，並使其配向固定而製作。 [液晶性組合物] 垂直配向液晶膜之製作中所使用之液晶性組合物包含側鏈型液晶聚合物、及光聚合性液晶單體。 ＜側鏈型液晶聚合物＞ 作為側鏈型液晶聚合物，可使用具有含有液晶性片段側鏈之單體單元與含有非液晶性片段側鏈之單體單元之共聚物。藉由聚合物於側鏈具有液晶性片段，於將液晶性組合物加熱至特定溫度時，聚合物進行垂直配向。又，藉由聚合物於側鏈具有非液晶性片段，使液晶性組合物中所含之光聚合性液晶單體與聚合物一起進行垂直配向之配向力起作用。藉由使液晶單體隨側鏈型液晶聚合物之配向而配向，並使該配向狀態固定，可獲得垂直配向液晶膜。 作為具有液晶性片段側鏈之單體，可列舉具有包含液晶原基之向列型液晶性之取代基之聚合性化合物。作為液晶原基，可列舉：聯苯基、苯基苯甲酸酯基、苯基環己烷基、氧化偶氮苯基、次甲基偶氮基、偶氮苯基、苯基嘧啶基、二苯基乙炔基、二苯基苯甲酸酯基、雙環己烷基、環己基苯基、聯三苯基等環狀結構。該等環狀單元之末端亦可具有氰基、烷基、烷氧基、鹵基等取代基。其中，作為液晶原基，較佳為具有聯苯基、苯基苯甲酸酯基者。 作為具有非液晶性片段側鏈之單體，可列舉具有碳數7以上之長鏈烷基等直鏈狀之取代基之聚合性化合物。作為液晶性單體及非液晶性單體之聚合性官能基，例如可列舉(甲基)丙烯醯基。 作為側鏈型液晶聚合物，可較佳地使用具有通式(I)所表示之液晶性單體單元與通式(II)所表示之非液晶性單體單元之共聚物。 [化1][化2]於式(I)中，R1
為氫原子或甲基，R2
為氰基、氟基、碳數1~6之烷基、或碳數1~6之烷氧基，X1
為-CO2
-或-OCO-。a為1~6之整數，b及c分別獨立地為1或2。 於式(II)中，R3
為氫原子或甲基，R4
為碳數7~22之烷基、碳數1~22之氟烷基、或下述通式(III)所表示之基。 [化3]於式(III)中，R5
為碳數1~5之烷基，d為1~6之整數。 側鏈型液晶聚合物中之液晶性單體單元與非液晶性單體單元之比率並無特別限定，於非液晶性單體單元之比率較少之情形時，存在伴隨側鏈型液晶聚合物之配向之光聚合性液晶化合物之配向變得不充分，光硬化後之液晶層之配向變得不均勻之情形。另一方面，於液晶性單體單元之比率較少之情形時，側鏈型液晶聚合物不易顯示出液晶單域配向性。因此，非液晶性單體相對於液晶性單體單元與非液晶性單體單元之合計之比率以莫耳比計較佳為0.01~0.8，更佳為0.1~0.6，進而較佳為0.15~0.5。就同時實現液晶性組合物之成膜性與配向性之觀點而言，側鏈型液晶聚合物之重量平均分子量較佳為2000~100000左右，更佳為2500~50000左右。 側鏈型液晶聚合物可藉由各種公知之方法進行聚合。例如，於單體單元具有(甲基)丙烯醯基作為聚合性官能基之情形時，藉由利用光或熱之自由基聚合，可獲得具有液晶性片段及非液晶性片段之側鏈型液晶聚合物。 ＜光聚合性液晶化合物＞ 光聚合性液晶化合物(單體)於1分子中具有液晶原基與至少1個光聚合性官能基。作為液晶原基，可列舉上文作為側鏈型液晶聚合物之液晶性片段所述者。作為光聚合性官能基，可列舉：(甲基)丙烯醯基、環氧基、乙烯醚基等。其中，較佳為(甲基)丙烯醯基。 光聚合性液晶單體較佳為於1分子中具有2個以上之光聚合性官能基者。藉由使用包含2個以上之光聚合性官能基之液晶單體，而向光聚合後之液晶層中導入交聯結構，故而有垂直配向液晶膜之耐久性提高之傾向。 作為於1分子中具有液晶原基與複數個(甲基)丙烯醯基之光聚合性液晶單體，例如可列舉下述通式(IV)所表示之化合物。 [化4]於式(IV)中，R為氫原子或甲基，A及D分別獨立地為1,4-伸苯基或1,4-伸環己基，B為1,4-伸苯基、1,4-伸環己基、4,4'-伸聯苯基或4,4'-伸聯環己基，Y及Z分別獨立地為-COO-、-OCO-或-O-。g及h分別獨立地為2~6之整數。 作為上述通式(IV)所表示之光聚合性液晶單體之市售品，可例示BASF公司製造之「Paliocolor LC242」。 ＜組成＞ 液晶性組合物中之光聚合性液晶化合物(單體)與側鏈型液晶聚合物之比率並無特別限制。就獲得耐久性較高之垂直配向液晶膜之觀點而言，較佳為光聚合性液晶化合物之含量多於側鏈型液晶聚合物之含量。就獲得耐久性較高且配向均一性較高之垂直配向液晶膜之觀點而言，液晶性組合物中之光聚合性液晶化合物之含量(重量)較佳為側鏈型液晶聚合物之含量之1.5~15倍，更佳為2~10倍，進而較佳為2.5~6倍。 為了促進利用光照射之光聚合性液晶化合物之硬化，液晶性組合物較佳為含有光聚合起始劑。作為光聚合起始劑，例如可例示：BASF公司製造之Irgacure 907、Irgacure 184、Irgacure 651、Irgacure 369等。關於液晶性組合物中之光聚合起始劑之含量，相對於光聚合性液晶化合物100重量份，通常為0.5~20重量份左右，較佳為3~15重量份左右，更佳為5~10重量份左右。 藉由將側鏈型液晶聚合物、光聚合性液晶化合物及光聚合起始劑與溶劑混合，可製備液晶性組合物。溶劑只要係可溶解側鏈型液晶聚合物及光聚合性液晶化合物，且不會侵蝕膜基板(或侵蝕性較低)者，則並無特別限定，可列舉：氯仿、二氯甲烷、四氯化碳、二氯乙烷、四氯乙烷、三氯乙烯、四氯乙烯、氯苯、鄰二氯苯等鹵化烴類；苯酚、對氯苯酚等酚類；苯、甲苯、二甲苯、甲氧基苯、1,2-二甲氧基苯等芳香族烴類；丙酮、甲基乙基酮、甲基異丁基酮、環己酮、環戊酮、2-吡咯啶酮、N-甲基-2-吡咯啶酮等酮系溶劑；乙酸乙酯、乙酸丁酯等酯系溶劑；第三丁醇、甘油、乙二醇、三乙二醇、乙二醇單甲醚、二乙二醇二甲醚、丙二醇、二丙二醇、2-甲基-2,4-戊二醇等醇系溶劑；二甲基甲醯胺、二甲基乙醯胺等醯胺系溶劑；乙腈、丁腈等腈系溶劑；二乙醚、二丁醚、四氫呋喃等醚系溶劑；乙基賽路蘇、丁基賽路蘇等。液晶性組合物之濃度通常為3~50重量%左右，較佳為7~35重量%左右。 [膜基板] 於本發明中，作為供塗佈液晶性組合物之基板，可使用未設置垂直配向膜之膜基板。如上所述，由於液晶性組合物中之側鏈型液晶聚合物藉由加熱而進行垂直配向，故而無需於基板上設置垂直配向膜。藉由使用膜基板，可藉由卷對卷實施自向基板上之液晶性組合物之塗佈至液晶單體之利用光聚合之硬化之一系列步驟，故而可提高垂直配向液晶膜之生產性。 膜基板具有第一主面及第二主面，且於第一主面上塗佈液晶性組合物。構成膜基板之樹脂材料只要不溶解於液晶性組合物之溶劑中，且具有用以使液晶性組合物配向之加熱時之耐熱性，則並無特別限制，可列舉：聚對苯二甲酸乙二酯、聚萘二甲酸乙二酯等聚酯；聚乙烯、聚丙烯等聚烯烴；降烯系聚合物等環狀聚烯烴；二乙醯纖維素、三乙醯纖維素等纖維素系聚合物；丙烯酸系聚合物；苯乙烯系聚合物；聚碳酸酯、聚醯胺、聚醯亞胺等。其中，就容易獲得成形時之流動性優異，且平滑性較高之膜之方面而言，尤佳為使用降烯系聚合物膜作為膜基板。就將垂直配向液晶膜轉印至其他基材等時之剝離性優異之方面而言，亦較佳為降烯系聚合物膜。作為降烯系聚合物，可列舉：日本Zeon製造之Zeonor、Zeonex、JSR製造之Arton等。 作為膜基板，亦可使用延伸膜。藉由將膜進行延伸，使成膜時之模線等凹凸平滑化，故而有膜基板之平滑性提高，算術平均粗糙度Ra減小之傾向。就表面之均一性較高之方面而言，尤佳為使用雙軸延伸膜作為膜基板。 用作膜基板之延伸膜之面內延遲R0
通常為10 nm以上。於膜基板係具有10 nm以上之面內延遲之延伸膜之情形時，構成膜之聚合物沿特定方向(遲相軸方向或進相軸方向)優先地進行配向，故而有使液晶分子進行水平配向之配向限制力容易起作用，而阻礙液晶性組合物之垂直配向之傾向。如於下文中所詳細說明般，藉由降低使液晶分子進行垂直配向時之加熱溫度，於使用延伸膜基板之情形時，亦可獲得配向缺陷較少之垂直配向液晶膜。 若膜基板之面內延遲過大，則存在可減少配向缺陷之溫度較低，於該溫度範圍內難以使側鏈型液晶聚合物進行液晶相轉移之情形。因此，膜基板之面內延遲R0
較佳為500 nm以下，更佳為300 nm以下，進而較佳為200 nm以下。 膜基板之厚度並無特別限定，若考慮處理性等，則通常為10~200 μm左右。延伸膜之面內雙折射Δn(將面內延遲R0
除以厚度而得之值)較佳為0.01以下，更佳為0.008以下，進而較佳為0.006以下。 膜基板之第一主面之算術平均粗糙度Ra較佳為3 nm以下，更佳為2 nm以下，進而較佳為1.5 nm以下。藉由在Ra較小而平滑性較高之膜基板面塗佈液晶性組合物，有垂直配向液晶膜之配向缺陷減少之傾向。如上所述，藉由將膜進行延伸，有膜之Ra變小之傾向。因此，藉由使用延伸膜基板，有垂直配向液晶膜之配向缺陷減少之傾向。 由於膜基板之第一主面之表面形狀被轉印至形成於其上之垂直配向液晶膜，故而垂直配向液晶膜之基板面之Ra與基板之第一主面之Ra大致相等。因此，於使用第一主面之Ra為3 nm以下之膜基板之情形時，多數情況下液晶配向膜之基板面之Ra亦成為3 nm以下。又，有液晶性組合物之塗佈時之空氣面之Ra變得小於基板面之Ra之傾向。因此，若使用第一主面之Ra為3 nm以下之膜基板，則多數情況下垂直配向液晶膜之兩面之算術平均粗糙度成為3 nm以下。 為了將算術平均粗糙度設為上述範圍，膜基板較佳為於內部不含填料者。不含填料而表面之平滑性較高之膜由於滑動性較低，故而存在產生黏連，或產生卷對卷製程中之搬送不良或捲繞不良之情形。為了防止由高平滑性所引起之黏連或搬送不良等，可列舉於膜基板貼合滑動性較高之其他膜之方法、或於膜基板設置易滑層之方法。於膜基板貼合其他膜之情形時，就抑制由接著層等向第一主面(供塗佈液晶性組合物之面)之轉印所引起之不良情況(液晶之配向不良或光學缺陷等)之觀點而言，較佳為貼合於第二主面(與液晶性組合物之塗佈面相反之側之面)。其中，於卷對卷製程中，於膜基板之卷取時，附著於第二主面之黏著劑等轉移至第一主面，而有可能導致配向不良或光學之缺陷。 因此，較佳為藉由在膜基板之至少一面設置易滑層，而改善滑動性。作為易滑層，例如可列舉於聚酯、聚胺基甲酸酯等黏合劑中含有平均粒徑為100 nm以下之微小填料者。就維持將垂直配向液晶膜轉印至其他基材等時之剝離性，且抑制自膜基板剝離時易滑層向垂直配向液晶膜之轉印等不良情況之觀點而言，膜基板較佳為於供塗佈液晶性組合物之面不具有易滑層。即，較佳為使用於第二主面具有易滑層，且於第一主面不具有易滑層之膜基板。 [於膜基板上之垂直配向液晶膜之形成] 於膜基板上塗佈液晶性組合物，藉由加熱使液晶性聚合物成為液晶狀態，使液晶性分子進行垂直配向，其後進行冷卻而使配向固定化，並藉由光照射使液晶單體進行聚合或交聯，藉此可獲得垂直配向液晶膜。 於膜基板上塗佈液晶性組合物之方法並無特別限定，可採用旋轉塗佈、模嘴塗佈、接觸輥式塗佈、凹版塗佈、反向塗佈、噴塗、邁耶棒式塗佈、輥刀塗佈、氣刀塗佈等。於塗佈溶液後，去除溶劑，藉此於膜基板上形成液晶性組合物層。塗佈厚度較佳為以使溶劑乾燥後之液晶性組合物層之厚度(垂直配向液晶膜之厚度)成為0.5~5 μm左右之方式加以調整。 藉由對形成於膜基板上之液晶性組合物層進行加熱而成為液晶相，液晶性組合物進行垂直配向。加熱溫度並無特別限定，通常為40~200℃左右。若加熱溫度過低，則有向液晶相之轉移變得不充分之傾向，若加熱溫度過高，則有配向缺陷增加之傾向。因此，加熱溫度較佳為45~100℃，更佳為50~95℃，進而較佳為55~90℃。加熱時間只要以向液晶相之轉移變得充分之方式加以調整即可，通常為30秒~30分鐘左右。 於使用延伸膜基板之情形時，有伴隨加熱溫度之上升而由膜基板之分子配向所引起之水平配向限制力容易起作用，而垂直配向液晶膜之配向缺陷增大之傾向。因此，於使用延伸膜基板之情形時，較佳為於液晶性化合物轉移至液晶相之溫度範圍內之低溫下進行加熱。液晶配向時之加熱溫度T(℃)較佳為100-3.5×103
Δn以下。Δn為延伸膜基板之面內雙折射。加熱溫度T更佳為100-4×103
Δn以下，進而較佳為100-4.5×103
Δn以下。又，加熱溫度T較佳為100-0.1R0
以下，更佳為100-0.12R0
以下，進而較佳為100-0.13R0
以下。R0
為延伸膜基板之面內延遲。 於對液晶性組合物層進行加熱後，冷卻至液晶聚合物之玻璃轉移溫度以下之溫度，藉此使液晶性化合物之配向固定。冷卻方法並無特別限定，例如，只要自加熱氛圍中取出至室溫下即可。亦可進行空氣冷卻、水冷等強制冷卻。 對垂直配向經固定之液晶性組合物層進行光照射，使光聚合性液晶化合物進行聚合或交聯，藉此使光聚合性液晶化合物之配向固定，垂直配向液晶膜之耐久性提高。作為所照射之光，只要選擇光聚合起始劑發生裂解之波長之光即可，通常可使用紫外線。為了促進光聚合反應，光照射較佳為於氮氣等惰性氣體氛圍下進行。 [垂直配向液晶膜之特性及用途] 藉由上述而獲得之垂直配向液晶膜係面內延遲大致為0(例如5 nm以下，較佳為3 nm以下)，且厚度方向延遲為負(具有nz＞nx=ny之折射率各向異性)之正C板。垂直配向液晶膜之(nx-nz)與厚度之積所表示之厚度方向延遲Rt
例如為-50~-500 nm左右。 垂直配向液晶膜於偏光顯微鏡下觀察到之漏光(配向不良)較佳為每1 cm2
為1個以下，更佳為0.7個以下，進而較佳為0.5個以下。配向不良數係以對膜面內之10個部位進行觀察所得之平均值之形式而求出。如上所述，藉由使用平滑性較高之延伸膜基板，且將使液晶配向時之加熱溫度設為特定範圍，可獲得配向缺陷較少之垂直配向液晶膜。 垂直配向液晶膜可用作以視角補償等為目的之顯示器用光學膜。垂直配向液晶膜可於與膜基板積層之狀態下使用，亦可自膜基板剝離而使用。垂直配向液晶膜亦可自膜基板剝離，並與相位差膜、偏光板、玻璃等基材積層而使用。 [實施例] 以下，列舉垂直配向液晶膜之製作例更詳細地說明本發明，但本發明並不限定於下述例。 [液晶性組合物之製備] 使下述化學式(為n=0.35，為了便於說明而利用嵌段聚合物體表示)之重量平均分子量5000之側鏈型液晶聚合物20重量份、顯示向列型液晶相之聚合性液晶化合物(BASF製造之「Paliocolor LC242」)80重量份、及光聚合起始劑(BASF製造之「Irgacure 907」)5重量份溶解於環戊酮400重量份中而製備液晶性組合物。 [化5][實驗例1] 利用棒式塗佈機，以乾燥後之厚度成為1 μm之方式將上述液晶性組合物塗佈於未延伸之降烯系膜(日本Zeon製造之「Zeonor Film」、厚度：50 μm、面內延遲：0 nm、算術平均粗糙度：2.3 nm)，於表1所示之溫度(50~100℃)下加熱2分鐘而使液晶配向。其後，冷卻至室溫而使配向固定，並於氮氣氛圍下照射700 mJ/cm2
之紫外線，使液晶單體進行光硬化，而製作液晶配向膜。 [實驗例2] 於在一面具有易滑層之雙軸延伸降烯系膜(日本Zeon製造之「Zeonor Film」、厚度：52 μm、面內延遲：50 nm、未形成易滑層之面之算術平均粗糙度：1.2 nm)之未形成易滑層之面，塗佈上述液晶性組合物，以與實驗例1同樣之方式製作液晶配向膜。 [實驗例3] 於在一面具有易滑層之雙軸延伸降烯系膜(日本Zeon製造之「Zeonor Film」、厚度：33 μm、面內延遲：135 nm、未形成易滑層之面之算術平均粗糙度：1.0 nm)之未形成易滑層之面，塗佈上述液晶性組合物，以與實驗例1同樣之方式製作液晶配向膜。 [實驗例4] 於在一面具有易滑層之雙軸延伸降烯系膜(日本Zeon製造之「Zeonor Film」、厚度：34 μm、面內延遲：270 nm、未形成易滑層之面之算術平均粗糙度：0.9 nm)之未形成易滑層之面，塗佈上述液晶性組合物，以與實驗例1同樣之方式製作液晶配向膜。 [實驗例5] 於雙軸延伸聚對苯二甲酸乙二酯膜(三菱化學製造之「DIAFOILT 302」、厚度：75 μm)上，塗佈上述液晶性組合物，以與實驗例1同樣之方式製作液晶配向膜。 [實驗例6] 將使組成變更為側鏈型液晶聚合物50重量份、聚合性液晶化合物50重量份之液晶性組合物塗佈於與實驗例2中所使用者相同之雙軸延伸膜上，於80℃下加熱2分鐘後，進行冷卻及光硬化，而製作液晶配向膜。 [評價] (算術平均粗糙度) 根據使用掃描式探針顯微鏡(AFM)之1 μm見方之AFM觀察圖像，求出算術平均粗糙度。 (延遲) 延遲之測定係使用偏光相位差測定系統(Axometrics製造 製品名「AxoScan」)，於23℃之環境下，測定波長590 nm之值。液晶配向膜之延遲之測定係使用於在表面設置有黏著劑之玻璃板之黏著劑附設面上轉印有液晶配向膜之樣品，測定面內延遲R0
、及40°傾斜時之延遲，並根據該等測定值，將液晶配向膜之平均折射率設為1.52而算出厚度方向延遲Rt
。 (配向缺陷) 於表面設置有黏著劑之玻璃板之黏著劑附設面上，轉印液晶配向膜，並於正交偏光之偏光顯微鏡下觀察1 cm2
之區域，對局部之漏光之數量進行計數。每1個試樣於10個部位(合計10 cm2
)進行偏光顯微鏡觀察，將漏光之數量之平均設為每1 cm2
之配向缺陷數。將各實驗例中所獲得之液晶配向膜之每1 cm2
之配向缺陷數示於表1。 [表1]
(耐久性試驗) 將實驗例2之加熱溫度80℃下製作之液晶配向膜、及實驗例6之液晶配向膜轉印至表面設置有黏著劑之5 cm見方之玻璃板之黏著劑附設面上，進行100個循環之-40℃與85℃之熱循環。將熱循環試驗後之厚度方向延遲相對於熱循環試驗前之厚度方向延遲之值(相位差保持率)、以及熱循環試驗後之樣品之利用目測觀察確認到之龜裂之數量、及每1 cm2
之配向缺陷數示於表2。 [表2]
根據表2所示之結果可知，於實驗例2及實驗例6中，於熱循環試驗之前後均未確認到配向缺陷，液晶之垂直配向被固定。但是，於光聚合性液晶單體之含量較少之實驗例6中，於熱循環試驗後產生龜裂，與實驗例2相比相位差保持率降低。根據該結果可知，藉由提高液晶性組合物中之光聚合性液晶單體之比率，可獲得溫度循環耐久性較高之垂直配向液晶膜。 於使用面內雙折射較大之雙軸延伸PET膜之實驗例5中，於50~100℃之範圍之任一加熱溫度下每1 cm2
均確認到10個以上之配向缺陷。另一方面，於實驗例1~4中，與實驗例5相比配向缺陷較少，可見加熱溫度越低則配向缺陷數越減少之傾向。根據該等結果可知，藉由使用面內雙折射為特定範圍之膜基板，降低液晶配向時之加熱溫度，可獲得配向缺陷較少之垂直配向液晶膜。 若對比實驗例1與實驗例2，則於溫度50~90℃之範圍中，實驗例2之配向缺陷減少。另一方面，於溫度95℃及100℃下，實驗例2之配向缺陷數增大。於使用面內延遲R0
為50 nm之延伸膜基板之實驗例2中，於90℃以下之溫度下與實驗例1相比配向缺陷減少，相對於此，於使用R0
為135 nm之延伸膜基板之實驗例3中，配向缺陷減少之溫度範圍為50~80℃，於使用R0
為270 nm之延伸膜基板之實驗例3中，配向缺陷減少之溫度範圍為50~70℃。 由於實驗例2~4中所使用之膜基材之Ra相同，故而可謂延伸膜之R0
越小，可減少配向缺陷之溫度範圍越寬。可認為其原因在於，伴隨R0
之增大而構成膜基板之聚合物向特定方向之配向增大，因膜基板而使液晶分子進行水平配向之配向限制力容易起作用。 根據以上之結果可知，藉由調整使液晶配向時之加熱溫度，可獲得配向缺陷較少之垂直配向液晶膜。又，可認為延伸膜基板之供塗佈液晶性組合物之面之Ra較小亦有助於配向缺陷之減少。A liquid crystal alignment film is produced by coating a liquid crystal composition on a substrate and fixing the alignment thereof. [Liquid Crystal Composition] The liquid crystal composition used in the production of the vertical alignment liquid crystal film includes a side chain liquid crystal polymer and a photopolymerizable liquid crystal monomer. <Side-chain liquid crystal polymer> As the side-chain liquid crystal polymer, a copolymer having a monomer unit containing a liquid crystal segment side chain and a monomer unit containing a non-liquid crystal segment side chain can be used. Since the polymer has a liquid crystal segment in a side chain, the polymer is vertically aligned when the liquid crystal composition is heated to a specific temperature. In addition, since the polymer has a non-liquid crystalline segment in the side chain, the photo-polymerizable liquid crystal monomer contained in the liquid crystalline composition and the polymer are aligned with the vertical alignment force. By aligning the liquid crystal monomer with the alignment of the side chain liquid crystal polymer and fixing the alignment state, a vertically aligned liquid crystal film can be obtained. Examples of the monomer having a liquid crystal segment side chain include a polymerizable compound having a nematic liquid crystal substituent having a mesogen group. Examples of the mesogen include biphenyl, phenylbenzoate, phenylcyclohexane, azophenyloxy, methineazo, azophenyl, phenylpyrimidinyl, Ring structures such as diphenylethynyl, diphenylbenzoate, dicyclohexane, cyclohexylphenyl, and tritriphenyl. The ends of these cyclic units may have substituents such as cyano, alkyl, alkoxy, and halo. Among them, the mesogen is preferably one having a biphenyl group or a phenylbenzoate group. Examples of the monomer having a non-liquid crystal segment side chain include a polymerizable compound having a linear substituent such as a long-chain alkyl group having 7 or more carbon atoms. Examples of the polymerizable functional group of the liquid crystalline monomer and the non-liquid crystalline monomer include (meth) acrylfluorenyl groups. As the side chain liquid crystal polymer, a copolymer having a liquid crystalline monomer unit represented by the general formula (I) and a non-liquid crystal monomer unit represented by the general formula (II) can be preferably used. [Chemical 1] [Chemical 2] In formula (I), R 1 is a hydrogen atom or a methyl group, R 2 is a cyano group, a fluoro group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms, and X 1 is -CO 2 -or-OCO-. a is an integer from 1 to 6, and b and c are each independently 1 or 2. In formula (II), R 3 is a hydrogen atom or a methyl group, and R 4 is an alkyl group having 7 to 22 carbon atoms, a fluoroalkyl group having 1 to 22 carbon atoms, or a group represented by the following general formula (III) . [Chemical 3] In the formula (III), R 5 is an alkyl group having 1 to 5 carbon atoms, and d is an integer from 1 to 6. The ratio of the liquid crystalline monomer unit to the non-liquid crystalline monomer unit in the side chain liquid crystal polymer is not particularly limited. When the ratio of the non-liquid crystalline monomer unit is small, there is a side chain liquid crystal polymer. The alignment of the aligned photopolymerizable liquid crystal compound becomes insufficient, and the alignment of the liquid crystal layer after photo-hardening becomes uneven. On the other hand, when the ratio of the liquid crystalline monomer units is small, the side chain liquid crystal polymer is unlikely to exhibit liquid crystal single-domain alignment. Therefore, the ratio of the non-liquid crystalline monomer to the total of the liquid crystalline monomer unit and the non-liquid crystalline monomer unit is preferably 0.01 to 0.8, more preferably 0.1 to 0.6, and still more preferably 0.15 to 0.5 in terms of molar ratio. . From the viewpoint of simultaneously achieving the film-forming property and the alignment property of the liquid crystal composition, the weight average molecular weight of the side chain liquid crystal polymer is preferably about 2,000 to 100,000, and more preferably about 2500 to 50,000. The side chain liquid crystal polymer can be polymerized by various known methods. For example, when the monomer unit has a (meth) acrylfluorenyl group as a polymerizable functional group, a side chain liquid crystal having a liquid crystal segment and a non-liquid crystal segment can be obtained by radical polymerization using light or heat. polymer. <Photopolymerizable liquid crystal compound> The photopolymerizable liquid crystal compound (monomer) has a mesogen group and at least one photopolymerizable functional group in one molecule. Examples of the mesogenic group include those described above as the liquid crystal segment of the side chain liquid crystal polymer. Examples of the photopolymerizable functional group include a (meth) acrylfluorenyl group, an epoxy group, and a vinyl ether group. Among these, (meth) acrylfluorenyl is preferred. The photopolymerizable liquid crystal monomer is preferably one having two or more photopolymerizable functional groups in one molecule. By using a liquid crystal monomer containing two or more photopolymerizable functional groups and introducing a crosslinked structure into the liquid crystal layer after photopolymerization, the durability of the vertically aligned liquid crystal film tends to be improved. Examples of the photopolymerizable liquid crystal monomer having a mesogen and a plurality of (meth) acrylfluorenyl groups in one molecule include compounds represented by the following general formula (IV). [Chemical 4] In formula (IV), R is a hydrogen atom or a methyl group, A and D are independently 1,4-phenylene or 1,4-cyclohexyl, and B is 1,4-phenylene, 1, 4-Cyclohexyl, 4,4'-biphenyl, or 4,4'-bicyclohexyl, and Y and Z are each independently -COO-, -OCO-, or -O-. g and h are each independently an integer of 2-6. As a commercially available product of the photopolymerizable liquid crystal monomer represented by the general formula (IV), "Paliocolor LC242" manufactured by BASF can be exemplified. <Composition> The ratio between the photopolymerizable liquid crystal compound (monomer) and the side chain liquid crystal polymer in the liquid crystal composition is not particularly limited. From the viewpoint of obtaining a vertically aligned liquid crystal film having high durability, the content of the photopolymerizable liquid crystal compound is preferably more than the content of the side chain liquid crystal polymer. From the viewpoint of obtaining a vertically aligned liquid crystal film with higher durability and higher alignment uniformity, the content (weight) of the photopolymerizable liquid crystal compound in the liquid crystal composition is preferably the content of the side chain liquid crystal polymer. 1.5 to 15 times, more preferably 2 to 10 times, and even more preferably 2.5 to 6 times. In order to promote hardening of the photopolymerizable liquid crystal compound by light irradiation, the liquid crystal composition preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include Irgacure 907, Irgacure 184, Irgacure 651, and Irgacure 369 manufactured by BASF. The content of the photopolymerization initiator in the liquid crystal composition is usually about 0.5 to 20 parts by weight, preferably about 3 to 15 parts by weight, and more preferably 5 to 100 parts by weight of the photopolymerizable liquid crystal compound. About 10 parts by weight. A liquid crystal composition can be prepared by mixing a side chain liquid crystal polymer, a photopolymerizable liquid crystal compound, and a photopolymerization initiator with a solvent. The solvent is not particularly limited as long as it dissolves the side chain liquid crystal polymer and the photopolymerizable liquid crystal compound and does not erode the film substrate (or has low erodibility), and examples thereof include chloroform, dichloromethane, and tetrachloride Halogenated hydrocarbons such as carbonized carbon, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, o-dichlorobenzene; phenols such as phenol and p-chlorophenol; benzene, toluene, xylene, methyl chloride Aromatic hydrocarbons such as oxybenzene, 1,2-dimethoxybenzene; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N- Ketone solvents such as methyl-2-pyrrolidone; ester solvents such as ethyl acetate and butyl acetate; tertiary butanol, glycerol, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, and diethyl ether Glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol, and other alcohol-based solvents; dimethylformamide, dimethylacetamide, and other amine solvents; acetonitrile, butane Nitrile solvents such as nitrile; ether solvents such as diethyl ether, dibutyl ether, and tetrahydrofuran; ethyl cyrus, butyl cyrus and the like. The concentration of the liquid crystal composition is usually about 3 to 50% by weight, and preferably about 7 to 35% by weight. [Film substrate] In the present invention, as a substrate for applying a liquid crystal composition, a film substrate without a vertical alignment film can be used. As described above, since the side chain liquid crystal polymer in the liquid crystal composition is vertically aligned by heating, there is no need to provide a vertical alignment film on the substrate. By using a film substrate, a series of steps of applying a liquid crystal composition on a self-directed substrate to a liquid crystal monomer and curing by photopolymerization can be performed by a roll-to-roll method, so that the productivity of a vertically-aligned liquid crystal film can be improved. . The film substrate has a first main surface and a second main surface, and the liquid crystal composition is coated on the first main surface. The resin material constituting the film substrate is not particularly limited as long as it does not dissolve in the solvent of the liquid crystal composition and has heat resistance during heating to align the liquid crystal composition. Examples include polyethylene terephthalate. Polyesters such as diesters and polyethylene naphthalates; Polyolefins such as polyethylene and polypropylene; Cyclic polyolefins such as norbornene polymers; Cellulose polymerization such as diacetyl cellulose and triethyl cellulose Materials; acrylic polymers; styrenic polymers; polycarbonates, polyamides, polyimides, and the like. Among them, it is particularly preferable to use a norbornene-based polymer film as a film substrate in terms of easily obtaining a film having excellent fluidity at the time of molding and having high smoothness. In terms of excellent peelability when transferring the vertical alignment liquid crystal film to another substrate, etc., a norbornene-based polymer film is also preferred. Examples of the norylene polymer include Zeonor manufactured by Zeon Japan, Zeonex, Arton manufactured by JSR, and the like. As the film substrate, a stretched film may be used. By stretching the film, unevenness such as mold lines during film formation is smoothed. Therefore, the smoothness of the film substrate is improved, and the arithmetic average roughness Ra tends to decrease. In terms of higher surface uniformity, it is particularly preferable to use a biaxially stretched film as the film substrate. The in-plane retardation R 0 of the stretched film used as a film substrate is usually 10 nm or more. In the case where the film substrate is an extended film with an in-plane retardation of 10 nm or more, the polymers constituting the film are preferentially aligned in a specific direction (late phase axis direction or advance axis direction), so the liquid crystal molecules are leveled. The alignment restricting force of the alignment tends to work, and tends to hinder the vertical alignment of the liquid crystal composition. As described in detail below, by lowering the heating temperature when the liquid crystal molecules are aligned vertically, when a stretched film substrate is used, a vertically aligned liquid crystal film with fewer alignment defects can also be obtained. If the in-plane retardation of the film substrate is too large, the temperature at which alignment defects can be reduced may be low, and it may be difficult to cause side-chain liquid crystal polymers to undergo liquid crystal phase transfer within this temperature range. Therefore, the in-plane retardation R 0 of the film substrate is preferably 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less. The thickness of the film substrate is not particularly limited. In consideration of handling properties and the like, the thickness is usually about 10 to 200 μm. The in-plane birefringence Δn (value obtained by dividing the in-plane retardation R 0 by the thickness) of the stretched film is preferably 0.01 or less, more preferably 0.008 or less, and even more preferably 0.006 or less. The arithmetic mean roughness Ra of the first main surface of the film substrate is preferably 3 nm or less, more preferably 2 nm or less, and even more preferably 1.5 nm or less. By coating a liquid crystal composition on the surface of a film substrate having a small Ra and a high smoothness, there is a tendency that the alignment defects of the vertically aligned liquid crystal film are reduced. As described above, by stretching the film, the Ra of the film tends to decrease. Therefore, by using the stretched film substrate, there is a tendency that the alignment defects of the vertically aligned liquid crystal film are reduced. Since the surface shape of the first main surface of the film substrate is transferred to the vertically aligned liquid crystal film formed thereon, the Ra of the substrate surface of the vertically aligned liquid crystal film is substantially equal to the Ra of the first main surface of the substrate. Therefore, when a film substrate having a Ra of the first main surface of 3 nm or less is used, Ra of the substrate surface of the liquid crystal alignment film also becomes 3 nm or less in most cases. In addition, Ra of the air surface at the time of application of the liquid crystal composition tends to be smaller than Ra of the substrate surface. Therefore, if a film substrate having a Ra of the first main surface of 3 nm or less is used, the arithmetic average roughness of the two surfaces of the vertically aligned liquid crystal film in most cases becomes 3 nm or less. In order to set the arithmetic mean roughness to the above range, it is preferable that the film substrate does not contain a filler inside. Films that do not contain fillers and have high surface smoothness have low sliding properties, which may cause blocking, or may cause poor conveyance or poor winding during the roll-to-roll process. In order to prevent blocking or poor transportation due to high smoothness, a method of attaching another film having a high sliding property to the film substrate, or a method of providing an easy-slip layer on the film substrate can be cited. In the case where a film substrate is bonded to another film, it is possible to suppress defects (such as poor alignment of the liquid crystal or optical defects) caused by the transfer of an adhesive layer or the like to the first main surface (the surface on which the liquid crystal composition is applied). From the viewpoint of), it is preferably bonded to the second main surface (the surface opposite to the coating surface of the liquid crystalline composition). Among them, in the roll-to-roll manufacturing process, when the film substrate is rolled, the adhesive or the like attached to the second main surface is transferred to the first main surface, which may cause poor alignment or optical defects. Therefore, it is preferable to improve the sliding property by providing an easy slip layer on at least one side of the film substrate. Examples of the slippery layer include those containing a fine filler having an average particle diameter of 100 nm or less in an adhesive such as polyester and polyurethane. From the viewpoint of maintaining the releasability when transferring the vertically-aligned liquid crystal film to other substrates, and suppressing the troubles such as the transfer of the easy-sliding layer to the vertically-aligned liquid crystal film when peeling from the film substrate, the film substrate is preferably There is no slippery layer on the surface to which the liquid crystal composition is applied. That is, it is preferably used for a film substrate having an easy-slip layer on the second main surface and not having an easy-slip layer on the first main surface. [Formation of a liquid crystal film having a vertical alignment on a film substrate] A liquid crystal composition is coated on the film substrate, the liquid crystal polymer is brought into a liquid crystal state by heating, the liquid crystal molecules are aligned vertically, and then cooled to make The alignment is fixed, and the liquid crystal monomer is polymerized or crosslinked by light irradiation, thereby obtaining a vertical alignment liquid crystal film. The method for coating the liquid crystal composition on the film substrate is not particularly limited, and spin coating, die coating, contact roll coating, gravure coating, reverse coating, spray coating, and Meyer bar coating can be used. Cloth, roll knife coating, air knife coating, etc. After the solution is applied, the solvent is removed to form a liquid crystal composition layer on the film substrate. The coating thickness is preferably adjusted so that the thickness of the liquid crystalline composition layer (thickness of the vertical alignment liquid crystal film) after the solvent is dried becomes about 0.5 to 5 μm. The liquid crystal composition layer formed on the film substrate is heated to form a liquid crystal phase, and the liquid crystal composition is vertically aligned. The heating temperature is not particularly limited, but is usually about 40 to 200 ° C. If the heating temperature is too low, the transition to the liquid crystal phase tends to be insufficient, and if the heating temperature is too high, the alignment defects tend to increase. Therefore, the heating temperature is preferably 45 to 100 ° C, more preferably 50 to 95 ° C, and even more preferably 55 to 90 ° C. The heating time may be adjusted so that the transition to the liquid crystal phase becomes sufficient, and is usually about 30 seconds to 30 minutes. When a stretched film substrate is used, the horizontal alignment restricting force caused by the molecular alignment of the film substrate tends to act as the heating temperature increases, and the vertical alignment liquid crystal film tends to have increased alignment defects. Therefore, when the stretched film substrate is used, it is preferable to perform heating at a low temperature within a temperature range where the liquid crystal compound is transferred to the liquid crystal phase. The heating temperature T (° C) at the time of liquid crystal alignment is preferably 100-3.5 × 10 3 Δn or less. Δn is the in-plane birefringence of the stretched film substrate. The heating temperature T is more preferably 100-4 × 10 3 Δn or less, and still more preferably 100-4.5 × 10 3 Δn or less. Further, the heating temperature T is preferably 100-0.1R 0 or less, more preferably 100-0.12R 0 or less, and further preferably 100-0.13R 0 or less. R 0 is the in-plane retardation of the stretched film substrate. After heating the liquid crystal composition layer, the liquid crystal composition is cooled to a temperature below the glass transition temperature of the liquid crystal polymer, thereby fixing the alignment of the liquid crystal compound. The cooling method is not particularly limited, and for example, it may be taken out from a heating atmosphere to room temperature. Forced cooling such as air cooling and water cooling are also available. The vertical alignment fixed liquid crystal composition layer is irradiated with light to polymerize or crosslink the photopolymerizable liquid crystal compound, thereby fixing the alignment of the photopolymerizable liquid crystal compound and improving the durability of the vertical alignment liquid crystal film. As the light to be irradiated, light having a wavelength at which the photopolymerization initiator is cleaved may be selected, and usually ultraviolet rays may be used. In order to promote the photopolymerization reaction, light irradiation is preferably performed in an inert gas atmosphere such as nitrogen. [Characteristics and uses of vertical alignment liquid crystal film] The in-plane retardation of the vertical alignment liquid crystal film obtained by the above is approximately 0 (for example, 5 nm or less, preferably 3 nm or less), and the retardation in the thickness direction is negative (having nz > Nx = ny refractive index anisotropy) positive C plate. The thickness direction retardation R t represented by the product of (nx-nz) and thickness of the vertical alignment liquid crystal film is, for example, about -50 to -500 nm. The light leakage (poor alignment) observed in the vertically aligned liquid crystal film under a polarizing microscope is preferably 1 or less per 1 cm 2 , more preferably 0.7 or less, and even more preferably 0.5 or less. The number of misalignments is determined as an average value obtained by observing 10 locations in the film surface. As described above, by using a stretched film substrate having high smoothness and setting the heating temperature during liquid crystal alignment to a specific range, a vertical alignment liquid crystal film with fewer alignment defects can be obtained. The vertical alignment liquid crystal film can be used as an optical film for a display for the purpose of viewing angle compensation and the like. The vertical alignment liquid crystal film can be used in a state of being laminated with a film substrate, or can be used by being peeled from the film substrate. The vertical alignment liquid crystal film can also be peeled from the film substrate and laminated with a substrate such as a retardation film, a polarizing plate, and glass to be used. [Examples] Hereinafter, the present invention will be described in more detail by making examples of a vertical alignment liquid crystal film, but the present invention is not limited to the following examples. [Preparation of liquid crystal composition] 20 parts by weight of a side chain type liquid crystal polymer having a weight average molecular weight of 5000 and a nematic liquid crystal of the following chemical formula (where n = 0.35 is used for convenience of explanation) 80 parts by weight of a polymerizable liquid crystal compound ("Paliocolor LC242" manufactured by BASF) and 5 parts by weight of a photopolymerization initiator ("Irgacure 907" manufactured by BASF) were dissolved in 400 parts by weight of cyclopentanone to prepare liquid crystallinity. combination. [Chemical 5] [Experimental Example 1] Using a bar coater, the above liquid crystal composition was applied to an unstretched norbornene film ("Zeonor Film" manufactured by Zeon, Japan) so that the thickness became 1 μm after drying. Thickness: 50 μm, in-plane retardation: 0 nm, arithmetic average roughness: 2.3 nm), and the liquid crystals were aligned by heating at the temperature (50 to 100 ° C.) shown in Table 1 for 2 minutes. Thereafter, the alignment was fixed by cooling to room temperature, and 700 mJ / cm 2 of ultraviolet light was irradiated in a nitrogen atmosphere to light-harden the liquid crystal monomer to produce a liquid crystal alignment film. [Experimental Example 2] A biaxially-stretched norbornene-based film ("Zeonor Film" manufactured by Zeon, Japan, thickness: 52 μm, in-plane retardation: 50 nm, non-slip layer-formed surface) The surface on which no slippery layer was formed (arithmetic average roughness: 1.2 nm) was coated with the liquid crystal composition, and a liquid crystal alignment film was produced in the same manner as in Experimental Example 1. [Experimental Example 3] On a surface of a biaxially-stretched norbornene-based film ("Zeonor Film" manufactured by Zeon, Japan, thickness: 33 μm, in-plane retardation: 135 nm, on a surface without an easy-slip layer) The surface on which no slippery layer was formed (arithmetic average roughness: 1.0 nm) was coated with the liquid crystal composition, and a liquid crystal alignment film was produced in the same manner as in Experimental Example 1. [Experimental Example 4] On a surface of a biaxially-stretched norbornene-based film ("Zeonor Film" manufactured by Zeon, Japan, thickness: 34 μm, in-plane retardation: 270 nm, on a surface without an easy-slip layer) The surface on which no slippery layer was formed (arithmetic average roughness: 0.9 nm) was coated with the above-mentioned liquid crystal composition, and a liquid crystal alignment film was produced in the same manner as in Experimental Example 1. [Experimental Example 5] The above-mentioned liquid crystal composition was coated on a biaxially-stretched polyethylene terephthalate film ("DIAFOILT 302" manufactured by Mitsubishi Chemical Corporation, thickness: 75 μm) to be the same as that of Experimental Example 1. Method to produce a liquid crystal alignment film. [Experimental Example 6] A liquid crystal composition having a composition changed to 50 parts by weight of a side chain liquid crystal polymer and 50 parts by weight of a polymerizable liquid crystal compound was coated on the same biaxially stretched film as the user used in Experimental Example 2. After being heated at 80 ° C. for 2 minutes, cooling and photo-hardening were performed to prepare a liquid crystal alignment film. [Evaluation] (Arithmetic Mean Roughness) The arithmetic mean roughness was determined from an AFM observation image of 1 μm square using a scanning probe microscope (AFM). (Delay) The measurement of the retardation was performed by using a polarized retardation measurement system (Axometrics product name "AxoScan") under a 23 ° C environment to measure a wavelength of 590 nm. The measurement of the retardation of the liquid crystal alignment film is a sample in which a liquid crystal alignment film is transferred on the adhesive attachment surface of a glass plate provided with an adhesive on the surface, and the in-plane retardation R 0 and the retardation at a tilt of 40 ° are measured, and Based on these measured values, the thickness-direction retardation R t was calculated by setting the average refractive index of the liquid crystal alignment film to 1.52. (Alignment defect) On the adhesive attachment surface of a glass plate with an adhesive on the surface, transfer the liquid crystal alignment film, and observe the area of 1 cm 2 under a polarizing microscope with orthogonal polarization, and count the number of local light leaks. . Polarized light microscope observation was performed at 10 locations (total 10 cm 2 ) for each sample, and the average number of light leaks was set to the number of alignment defects per 1 cm 2 . Table 1 shows the number of alignment defects per 1 cm 2 of the liquid crystal alignment film obtained in each experimental example. [Table 1] (Durability test) The liquid crystal alignment film prepared at a heating temperature of 80 ° C. in Experimental Example 2 and the liquid crystal alignment film of Experimental Example 6 were transferred to an adhesive attachment surface of a 5 cm square glass plate with an adhesive on the surface. , Perform 100 cycles of -40 ° C and 85 ° C thermal cycles. The value of the retardation in the thickness direction after the thermal cycle test relative to the retardation in the thickness direction before the thermal cycle test (phase difference retention ratio), the number of cracks confirmed by visual observation of the sample after the thermal cycle test, and with 2 cm of the number of defects is shown in table 2. [Table 2] From the results shown in Table 2, it can be seen that in Experimental Example 2 and Experimental Example 6, no alignment defect was confirmed before and after the thermal cycle test, and the vertical alignment of the liquid crystal was fixed. However, in Experimental Example 6 in which the content of the photopolymerizable liquid crystal monomer was small, cracks occurred after the thermal cycle test, and the retardation retention ratio was lower than that in Experimental Example 2. From this result, it is understood that by increasing the ratio of the photopolymerizable liquid crystal monomer in the liquid crystal composition, a vertically aligned liquid crystal film having high temperature cycle durability can be obtained. In Experimental Example 5 using a biaxially stretched PET film having a large in-plane birefringence, more than 10 alignment defects were confirmed per 1 cm 2 at any heating temperature ranging from 50 to 100 ° C. On the other hand, in Experimental Examples 1 to 4, there are fewer alignment defects than Experimental Example 5. It can be seen that the lower the heating temperature, the fewer the number of alignment defects. From these results, it can be seen that by using a film substrate having a specific range of in-plane birefringence and lowering the heating temperature during liquid crystal alignment, a vertically aligned liquid crystal film with fewer alignment defects can be obtained. If Experimental Example 1 is compared with Experimental Example 2, the alignment defects in Experimental Example 2 are reduced in the temperature range of 50 to 90 ° C. On the other hand, at temperatures of 95 ° C and 100 ° C, the number of alignment defects in Experimental Example 2 increased. In Experimental Example 2 using an extended film substrate with an in-plane retardation R 0 of 50 nm, alignment defects are reduced at a temperature below 90 ° C. compared to Experimental Example 1. In contrast, an extension with R 0 of 135 nm is used. In Experimental Example 3 of the film substrate, the temperature range for reduction of alignment defects is 50 to 80 ° C. In Experimental Example 3 of the stretched film substrate with R 0 at 270 nm, the temperature range of reduction of alignment defects is 50 to 70 ° C. Since Ra of the film substrate used in Experimental Examples 2 to 4 is the same, it can be said that the smaller R 0 of the stretched film is, the wider the temperature range in which alignment defects can be reduced. This is considered to be because the alignment of the polymer constituting the film substrate in a specific direction increases with an increase in R 0 , and the alignment limiting force for horizontal alignment of the liquid crystal molecules due to the film substrate is likely to act. From the above results, it can be seen that by adjusting the heating temperature when the liquid crystal is aligned, a vertical alignment liquid crystal film with fewer alignment defects can be obtained. In addition, it is considered that the smaller Ra of the surface of the stretched film substrate on which the liquid crystal composition is applied also contributes to the reduction of alignment defects.