[0022] 以下，詳細說明本發明的一實施方式。在本發明的實施方式的示例中，關注隔膜的保液能力，採用能夠確保規定以上的保液率的結構。 [0023] 當在一對電極之間夾持隔膜並捲繞而形成電容器元件時，隔膜成為被兩個電極箔壓縮的狀態。在浸潤性高的隔膜的情況下，雖然對於縮短浸潤時間等有效果，但是在這種壓縮狀態下，有時無法增加導電性高分子的保持量。因此，在本實施方式的示例中，不選取吸液度、吸水度等浸潤性，而是設想形成該電容器元件的狀態，採取可確保規定的壓縮保液率的結構。 [0024] 即，本實施方式的隔膜是***在一對電極之間的鋁電解電容器用隔膜，該隔膜的壓縮保液率為130%以上。壓縮保液率優選為160%以上，更優選為190%以上。隔膜的壓縮保液率沒有特別的上限，但是根據能夠適用於實際的電容器的隔膜的厚度、密度來判斷的話，可認為300%左右是上限。 [0025] 在本實施方式的示例的隔膜中，通過使壓縮保液率為130%以上可減小ESR。這是因為在壓縮保液率小於130%的保液能力的情況下，存在無法充分地減小ESR的情況。 [0026] 需要說明的是，這裡所說的壓縮保液率是指將隔膜浸漬在乙醇中後進行壓縮，根據乾燥狀態的質量與壓縮後的質量之差算出的保液率，將其用作測量隔膜的性能的指標。 [0027] 具體地，測量一定面積的隔膜的乾燥狀態的質量，此後，將該隔膜浸漬在乙醇中後取出，對該隔膜以7kN/m2
進行加壓後，測量質量，根據乾燥狀態的質量與壓縮後的質量之差計算出壓縮保液率。如果是壓縮保液率，則能夠調查保持有液體的隔膜被施加負載後的保液能力，能夠用作適當地測量元件捲繞後的隔膜的保液能力的指標。需要說明的是，為了使隔膜試驗片完全地浸漬有乙醇，浸漬時間選用30秒。 [0028] 在本實施方式中，不關注隔膜的浸潤性而關注保液能力的理由是，在隔膜的浸潤性良好的情況下，對導電性高分子的聚合液、分散液浸潤良好，電容器的容量表現率提高，ESR也改善，但是如上述，近年需要進一步的低ESR化，為了回應此需求，可知不僅浸潤性的評價重要，保液能力也很重要。如果是以比施加於元件捲繞後的隔膜的負載更強的7kN/m2
進行加壓後，壓縮保液率為130%以上的隔膜，則可以說是保液能力高的隔膜。 [0029] 因此，當保液能力升高時，能夠在電容器電極箔表面以及甚至在電極箔之間的邊邊角角處形成導電性高分子，能夠改善ESR特性。 [0030] 根據本實施方式，通過選用保液能力高的隔膜，隔膜能夠足量地保持導電性高分子的聚合液、分散液，導電性高分子的保持量也增加。另外，通過使隔膜含有20質量%以上的合成纖維，隔膜的耐酸性、耐氧化性提高，能夠避免導電性高分子的聚合液、分散液導致的隔膜的機械強度降低。 [0031] 在合成纖維的含有量小於20質量%的情況下，即，當纖維素纖維之類的天然纖維的含有量超過80質量%時，隔膜的耐酸性、耐氧化性降低，隔膜的機械強度降低，因此電容器的短路故障率有增加的可能性。 [0032] 作為在本實施方式的示例中使用的合成纖維，從隔膜的耐酸性、耐氧化性的觀點出發，優選尼龍纖維、芳綸纖維、丙烯酸纖維、聚酯纖維。 [0033] 這些合成纖維可使用一種，也可使用多種。這些合成纖維的中，從對導電性高分子的聚合液、分散液的親和性的觀點出發，更優選尼龍纖維之類的聚醯胺纖維。而且，這些合成纖維可以是原纖化纖維，也可以是非原纖化纖維。 [0034] 另外，如果是避免有延伸度而製造的聚酯纖維(以下，稱作“未延伸聚酯纖維”)，則由於纖維的交織點黏著，因此有助於提高隔膜的機械強度等的物理性能。只要能夠滿足所需的壓縮保液率，未延伸聚酯纖維的含有量沒有特別限制，但是如果是達到50質量%左右，則壓縮保液率難以降低。 [0035] 本實施方式的示例的隔膜含有20質量%以上的合成纖維即可，作為構成隔膜的其他材料，合成纖維也好合成纖維之外的纖維也好，均沒有限制。在合成纖維的情況下可以使用上述以外的纖維，在合成纖維以外的纖維的情況下，也能夠使用纖維素之類的天然纖維。 [0036] 另外，考慮隔膜成形時、捲繞時等的機械強度，在不影響壓縮保液率的範圍內，也能夠使用聚乙烯醇纖維之類的黏合纖維。雖然只要能夠滿足所需的壓縮保液率，黏合纖維的含有量沒有特別限制，但是如果達到15質量%左右，則壓縮保液率難以降低。 [0037] 通過使隔膜的微細纖維的含有比例在0.1~8.0%的範圍內，能夠提高隔膜的壓縮保液率，能夠提高保液能力。雖然詳情不明，但是可認為通過使微細纖維的含有比例為0.1~8.0%，微細纖維成為適當地分散的狀態，起到了對抗壓縮的緩衝材料的作用。也就是說，可認為隔膜對壓縮具有抗力，能夠維持厚度且保液能力不會降低。 [0038] 需要說明的是，本實施方式中的微細纖維是指，纖維長度為0.05mm以上且小於0.2mm的纖維。作為得到微細纖維的方法，例如只要是通常製備抄紙原料所使用的方法即可，一般可使用打漿機、錐形磨漿機、盤狀精磨機、高壓均質機等。 [0039] 纖維長度小於0.05mm的纖維，在片材成形時會流出。另外，0.2mm以上的纖維的情況下，纖維彼此會纏結，因此在隔膜中不會成為適當的分散狀態，無法起作為緩衝材料的作用。 [0040] 微細纖維的含有比例小於0.1%的情況下，存在微細纖維作為緩衝材料的作用的效果降低，難以承受加壓，隔膜的保液能力有降低的情況。另外，當微細纖維的含有比例超過8.0%時，隔膜過於緻密，纖維彼此間的間隙變小。由此，存在無法顯現隔膜的保液能力的情況。 [0041] 本實施方式的隔膜的厚度以及密度，沒有特別限制，能夠採用滿足所需的鋁電解電容器的特性的厚度以及密度。一般使用厚度為20~70μm、密度為0.20~0.60g/cm3
左右的隔膜，但是不限於該範圍。 [0042] 在本發明的實施方式中，隔膜採用使用抄紙法形成的濕式不織布。隔膜的抄紙方式，只要能夠滿足壓縮保液率或微細纖維的含有比例即可，沒有特別限制，能夠使用長網抄紙、短網抄紙、圓網抄紙等抄紙方式，另外，也可以是組合多個通過這些抄紙法形成的層得到的隔膜。 [0043] 另外，在抄紙時，只要是不會對電容器用隔膜產生影響的程度的雜質含有量，即可添加分散劑、消泡劑、紙力增強劑等添加劑，也可以在紙層形成後進行紙力增強加工、親液加工、壓光加工，壓花加工等加工。 [0044] 通過採用以上的結構，本實施方式的隔膜形成了均勻的電子傳導路徑，或者，有助於增加導電性高分子的保持量。而且，通過將該隔膜用於使用導電性高分子作為陰極材料的鋁電解電容器，能夠得到低ESR的鋁電解電容器。 [0045] 本實施方式的鋁電解電容器，使用上述結構的隔膜作為隔膜，在一對電極之間***該隔膜，使用導電性高分子作為陰極材料。 [0046] (隔膜以及鋁電解電容器的特性的測量方法) 本實施方式的隔膜以及鋁電解電容器的各特性的具體的測量，按照以下的條件以及方法進行。 [0047] (加拿大標準濾水度(CSF)) 按照“JIS P8121-2 《紙漿-濾水度試驗法-第2部：加拿大標準濾水度法》(ISO5267-2《Pulps-Determination of drainability-Part2: “Canadian Standard” freeness method》)”，測量CSF。 [0048] (厚度) 使用“JIS C 2300-2 《電氣用纖維素紙-第2部：試驗方法》5.1 厚度”所規定的，“5.1.1 測量用具以及測量方法 a 使用外側千分尺的情況”的千分尺，按照“5.1.3 折疊紙測量厚度的情況”的折疊成10張的方法，測量隔膜的厚度。 [0049] (密度) 按照“JIS C 2300-2 《電氣用纖維素紙-第2部：試驗方法》7.0A 密度”的B法規定的方法，測量絕對乾燥狀態的隔膜的密度。 [0050] (微細纖維的含有比例) 微細纖維的含有比例是，使用“JIS P 8226-2 《紙漿-光學自動分析法的纖維長度測量方法-第2部：非偏振光法》(ISO16065-2《Pulps-Determination of Fiber length by automated optical analysis-Part2: Unpolarized light method》)”中記載的裝置，此處使用kajaani Fiber Lab(Metso自動化有限公司製造)在0.05~7.6mm的範圍內測量長度加權平均纖維長度分布，計算出纖維長度為0.05mm以上且小於0.2mm的微細纖維的含有比例。 [0051] (壓縮保液率) 測量浸漬前的隔膜的質量。另外，將隔膜在20℃的乙醇中浸漬30秒，以7kN/m2
進行加壓後，測量質量，通過以下的公式1計算出壓縮保液率。 需要說明的是，測量在室溫20℃、相對濕度65%的環境下進行。 壓縮保液率(%)＝[(W2-W1)/W1]×100 (公式1) W1：浸漬前的試驗片質量(g) W2：加壓後的試驗片質量(g) [0052] (吸水速度) 吸水速度的測量，使用“JIS C 2300-2 《電氣用纖維素紙-第2部：試驗方法》22吸水度”的B法規定的方法，測量1分鐘內被吸上來的水的高度作為吸水速度(mm/分)。雖然在專利文獻2中隔膜寬度為20mm，但是按照JIS記載的寬度進行測量。 [0053] (橫向的吸液度) 使用吸液度作為隔膜的浸潤性的指標。可認為當吸液度升高時，隔膜的浸潤性變高。需要說明的是，吸液度的測量，使用“JIS C 2300-2 《電氣用纖維素紙-第2部：試驗方法》22吸水度”的B法規定的方法，將水更換為乙醇進行測量。另外，考慮電容器的浸潤步驟，吸液方向選用隔膜的橫向。 [0054] (固態電解電容器的製作步驟) 使用各實施例、比較例、現有例的隔膜，製作額定電壓6.3V、直徑10.0mm×高度10.0mm的固態電解電容器，和額定電壓50V、直徑10.0mm×高度15.0mm的固態電解電容器。 [0055] 具體的製作方法如下。 以進行了蝕刻處理以及氧化膜形成處理的陽極箔和陰極箔沒有接觸的方式***隔膜並捲繞，製作電容器元件。製作的電容器元件在再次化學轉化處理後進行乾燥。 [0056] 在額定電壓6.3V的固態電解電容器的情況下，使電容器元件浸潤導電性高分子聚合液後，進行加熱/聚合，並乾燥溶劑形成導電性高分子。在額定電壓50V的固態電解電容器的情況下，使電容器元件浸潤導電性高分子水分散液後，進行加熱/乾燥形成導電性高分子。 接著，將電容器元件放入規定的外殼內，並封閉開口部後，進行老化，得到額定電壓不同的兩種固態電解電容器。 [0057] (混合型電解電容器的製作步驟) 使用各實施例、比較例、現有例的隔膜製作額定電壓16V、直徑10.0mm×高度12.5mm的混合型電解電容器，和額定電壓80V、直徑10.0mm×高度10.5mm的混合型電解電容器。 [0058] 具體的製作方法如下。 以進行了蝕刻處理以及氧化膜形成處理的陽極箔和陰極箔沒有接觸的方式***隔膜並捲繞，製作電容器元件。製作的電容器元件在再次化學轉化處理後進行乾燥。 [0059] 在額定電壓16V的混合型電解電容器的情況下，使電容器元件浸潤導電性高分子聚合液後，進行加熱/聚合，並乾燥溶劑形成導電性高分子。在額定電壓80V的混合型電解電容器的情況下，使電容器元件浸潤導電性高分子分散液後，進行加熱/乾燥形成導電性高分子。 [0060] 接著，使上述電容器元件浸潤驅動用電解液，將電容器元件裝入規定的外殼內，並封閉開口部後，進行老化，得到額定電壓不同的兩種混合型電解電容器。 [0061] (鋁電解電容器的評價方法) 本實施方式的鋁電解電容器的具體的性能評價，按照以下的條件以及方法進行。 [0062] (ESR) 在溫度20℃、頻率100kHz的條件下使用LCR測量儀，測量製作的電容器元件的ESR。 [0063] (電靜電容量) 按照“JIS C 5101-1 《電子設備用固定電容器-第1部：項目類別通則》”規定的“4.7 靜電容量”的方法，求出靜電容量。 [0064] (短路故障率) 短路故障率是使用捲繞的電容器元件，計算老化中發生的短路故障個數，將短路故障的元件個數除以實施了老化的電容器元件數，以百分率表示短路故障率。 [0065] (實施例等) 以下，說明本發明的實施方式的隔膜的具體的實施例等。 [0066] (實施例1) 混合20質量%的半芳香族尼龍纖維，和80質量%(CSF500ml)的原纖化纖維素纖維。使用得到的原料進行圓網抄紙，得到實施例1的隔膜。該隔膜，厚度為50μm，密度為0.60g/cm3
，壓縮保液率為162%，吸水速度為25mm/分鐘，橫向的吸液度為26mm/(10分鐘)，微細纖維的含有比例為0.1%。 [0067] (實施例2) 混合20質量%的丙烯酸纖維，10質量%的聚酯纖維，和70質量%(CSF30ml)的原纖化芳綸纖維。使用得到的原料進行圓網抄紙，得到實施例2的隔膜。該隔膜的厚度為40μm，密度為0.30g/cm3
，壓縮保液率為221%，吸水速度為16mm/分鐘，橫向的吸液度為6mm/(10分鐘)，微細纖維的含有比例為7.7%。 [0068] (實施例3) 混合75質量%的半芳香族尼龍纖維，20質量%(CSF110ml)的原纖化纖維素纖維，和5質量%的聚乙烯醇纖維。使用得到的原料進行圓網抄紙，得到實施例3的隔膜。該隔膜，厚度為70μm，密度為0.20g/cm3
，壓縮保液率為289%，吸水速度為9mm/分鐘，橫向的吸液度為12mm/(10分鐘)，微細纖維的含有比例為3.6%。 [0069] (實施例4) 混合40質量%的芳綸纖維，45質量%(CSF210ml)的原纖化纖維素纖維，和15質量%的聚乙烯醇纖維。使用得到的原料進行圓網抄紙，得到實施例4的隔膜。該隔膜，厚度為20μm，密度為0.40g/cm3
，壓縮保液率為191%，吸水速度為4mm/分鐘，橫向的吸液度為20mm/(10分鐘)，微細纖維的含有比例為0.8%。 [0070] (實施例5) 混合30質量%的半芳香族尼龍纖維，20質量%的丙烯酸纖維，和50質量%的未延伸聚酯纖維。使用得到的原料進行圓網抄紙，得到實施例5的隔膜。該隔膜，厚度為30μm，密度為0.50g/cm3
，壓縮保液率為132%，吸水速度為33mm/分鐘，橫向的吸液度為24mm/(10分鐘)，微細纖維的含有比例為0.0%。 [0071] (實施例6) 混合65質量%的丙烯酸纖維，和35質量%(CSF20ml)的原纖化丙烯酸纖維。使用得到的原料進行圓網抄紙，得到實施例6的隔膜。該隔膜，厚度為50μm，密度為0.30g/cm3
，壓縮保液率為136%，吸水速度11mm/分鐘，橫向的吸液度為9mm/(10分鐘)，微細纖維的含有比例為8.6%。 [0072] (比較例1) 按照與專利文獻1的實施例1記載的方法相同的方法製造隔膜，將其用作比較例1的隔膜。比較例1的隔膜，含有70質量%的半芳香族尼龍纖維和30質量%的聚乙烯醇纖維，厚度為40μm，密度為0.27g/cm3
，壓縮保液率為105%，吸水速度為3mm/分鐘，橫向的吸液度為14mm/(10分鐘)，微細纖維的含有比例為0.0%。 [0073] (比較例2) 按照與專利文獻3的實施例1記載的方法相同的方法製作隔膜，將其用作比較例2的隔膜。比較例2的隔膜，含有35質量%的聚酯纖維和65質量%的未延伸聚酯纖維，厚度為50μm，密度為0.40g/cm3
，壓縮保液率為124%，吸水速度為14mm/分鐘，橫向的吸液度為19mm/(10分鐘)，微細纖維的含有比例為0.0%。 [0074] (比較例3) 混合15質量%的半芳香族尼龍纖維，和85質量%(CSF400ml)的原纖化纖維素纖維。使用得到的原料進行圓網抄紙，得到比較例3的隔膜。該隔膜，厚度為60μm，密度為0.40g/cm3
，壓縮保液率為139%，吸水速度為28mm/分鐘，橫向的吸液度為24mm/(10分鐘)，微細纖維的含有比例為1.0%。 [0075] (比較例4) 混合15質量%的丙烯酸纖維，25質量%的聚酯纖維，和60質量%(CSF200ml)的原纖化芳綸纖維。使用得到的原料進行圓網抄紙，得到比較例4的隔膜。該隔膜，厚度為50μm，密度為0.30g/cm3
，壓縮保液率為104%，吸水速度為12mm/分鐘，橫向的吸液度為16mm/(10分鐘)，微細纖維的含有比例為4.3%。 [0076] (現有例) 與專利文獻2的實施例1記載的方法相同地製作隔膜，用作現有例的隔膜。現有例的隔膜，含有30質量%(CSF12ml)的原纖化芳綸纖維，45質量%的聚酯纖維，和25質量%的未延伸聚酯纖維，厚度為45μm，密度為0.35g/cm3
，壓縮保液率為88%，吸水速度為10mm/分鐘，橫向的吸液度為6mm/(10分鐘)，微細纖維的含有比例為16.2%。 [0077] 本實施方式的各實施例、各比較例、現有例的隔膜個體的評價結果在表1中示出。另外，表1中還包含有吸水速度和橫向的吸液度。 [0078][0079] 使用各實施例、各比較例、現有例的隔膜製作的鋁電解電容器的性能評價結果在表2中示出。如表2所示，作為固態電解電容器，製作了低電壓用的額定電壓6.3V的電容器，和高電壓用的額定電壓50V的電容器。另外，作為混合型電解電容器，製作了低電壓用的額定電壓16V的電容器，和高電壓用的額定電壓80V的電容器。 [0080][0081] (使用實施例1的隔膜的固態電解電容器) 使用實施例1的隔膜的額定電壓6.3V的固態電解電容器的ESR為16mΩ，靜電容量為269μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為18mΩ，靜電容量為40μF，短路故障率為0%。 [0082] (使用實施例1的隔膜的混合型電解電容器) 使用實施例1的隔膜的額定電壓16V的混合型電解電容器的ESR為19mΩ，靜電容量為129μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為23mΩ，靜電容量為50μF，短路故障率為0%。 [0083] (使用實施例2的隔膜的固態電解電容器) 使用實施例2的隔膜的額定電壓6.3V的固態電解電容器的ESR為10mΩ，靜電容量為260μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為12mΩ，靜電容量為38μF，短路故障率為0%。 [0084] (使用實施例2的隔膜的混合型電解電容器) 使用實施例2的隔膜的額定電壓16V的混合型電解電容器的ESR為14mΩ，靜電容量為125μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為17mΩ，靜電容量為48μF，短路故障率為0%。 [0085] (使用實施例3的隔膜的固態電解電容器) 使用實施例3的隔膜的額定電壓6.3V的固態電解電容器的ESR為8mΩ，靜電容量為263μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為9mΩ，靜電容量為39μF，短路故障率為0%。 [0086] (使用實施例3的隔膜的混合型電解電容器) 使用實施例3的隔膜的額定電壓16V的混合型電解電容器的ESR為10mΩ，靜電容量為126μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為13mΩ，靜電容量為49μF，短路故障率為0%。 [0087] (使用實施例4的隔膜的固態電解電容器) 使用實施例4的隔膜的額定電壓6.3V的固態電解電容器的ESR為13mΩ，電靜電容量為267μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為14mΩ，靜電容量為39μF，短路故障率為0%。 [0088] (使用實施例4的隔膜的混合型電解電容器) 使用實施例4的隔膜的額定電壓16V的混合型電解電容器的ESR為16mΩ，電靜電容量為128μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為19mΩ，靜電容量為49μF，短路故障率為0%。 [0089] (使用實施例5的隔膜的固態電解電容器) 使用實施例5的隔膜的額定電壓6.3V的固態電解電容器的ESR為19mΩ，電靜電容量為269μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為22mΩ，靜電容量為40μF，短路故障率為0%。 [0090] (使用實施例5的隔膜的混合型電解電容器) 使用實施例5的隔膜的額定電壓16V的混合型電解電容器的ESR為24mΩ，電靜電容量為130μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為28mΩ，靜電容量為50μF，短路故障率為0%。 [0091] (使用實施例6的隔膜的固態電解電容器) 使用實施例6的隔膜的額定電壓6.3V的固態電解電容器的ESR為18mΩ，靜電容量為263μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為21mΩ，靜電容量為39μF，短路故障率為0%。 [0092] (使用實施例6的隔膜的混合型電解電容器) 使用實施例6的隔膜的額定電壓16V的混合型電解電容器的ESR為23mΩ，靜電容量為126μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為27mΩ，靜電容量為48μF，短路故障率為0%。 [0093] (使用比較例1的隔膜的固態電解電容器) 使用比較例1的隔膜的額定電壓6.3V的固態電解電容器的ESR為26mΩ，靜電容量為264μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為31mΩ，靜電容量為39μF，短路故障率為0%。 [0094] (使用比較例1的隔膜的混合型電解電容器) 使用比較例1的隔膜的額定電壓16V的混合型電解電容器的ESR為31mΩ，靜電容量為127μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為38mΩ，靜電容量為49μF，短路故障率為0%。 [0095] (使用比較例2的隔膜的固態電解電容器) 使用比較例2的隔膜的額定電壓6.3V的固態電解電容器的ESR為24mΩ，靜電容量為269μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為28mΩ，靜電容量為40μF，短路故障率為0%。 [0096] (使用比較例2的隔膜的混合型電解電容器) 使用比較例2的隔膜的額定電壓16V的混合型電解電容器的ESR為30mΩ，電靜電容量為129μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為35mΩ，靜電容量為50μF，短路故障率為0%。 [0097] (使用比較例3的隔膜的固態電解電容器) 使用比較例3的隔膜的額定電壓6.3V的固態電解電容器的ESR為17mΩ，電靜電容量為269μF，短路故障率為0.8%。額定電壓50V的固態電解電容器的ESR為20mΩ，靜電容量為39μF，短路故障率為0.7%。 [0098] (使用比較例3的隔膜的混合型電解電容器) 使用比較例3的隔膜的額定電壓16V的混合型電解電容器的ESR為21mΩ，電靜電容量為129μF，短路故障率為0.8%。額定電壓80V的混合型電解電容器的ESR為25mΩ，靜電容量為50μF，短路故障率為0.7%。 [0099] (使用比較例4的隔膜的固態電解電容器) 使用比較例4的隔膜的額定電壓6.3V的固態電解電容器的ESR為27mΩ，靜電容量為266μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為32mΩ，靜電容量為39μF，短路故障率為0%。 [0100] (使用比較例4的隔膜的混合型電解電容器) 使用比較例4的隔膜的額定電壓16V的混合型電解電容器的ESR為32mΩ，靜電容量為128μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為39mΩ，靜電容量為49μF，短路故障率為0%。 [0101] (使用現有例的隔膜的固態電解電容器) 使用現有例的隔膜的額定電壓6.3V的固態電解電容器的ESR為34mΩ，電靜電容量為250μF，短路故障率為0%。額定電壓50V的固態電解電容器的ESR為38mΩ，靜電容量為37μF，短路故障率為0%。 [0102] (使用現有例的隔膜的混合型電解電容器) 使用現有例的隔膜的額定電壓16V的混合型電解電容器的ESR為35mΩ，靜電容量為120μF，短路故障率為0%。額定電壓80V的混合型電解電容器的ESR為42mΩ，靜電容量為46μF，短路故障率為0%。 [0103] 由以上可知，使用實施例1~4的隔膜的額定電壓6.3V的固態電解電容器，ESR較低為8~16mΩ，靜電容量為260~269μF，沒有發生短路故障。使用相同隔膜的額定電壓50V的固態電解電容器的ESR也較低為9~18mΩ，靜電容量為38~40μF，也沒有發生短路故障。 [0104] 另外，在使用實施例1~4的隔膜的額定電壓16V的混合型電解電容器的評價中，ESR較低為10~19mΩ，靜電容量為125~129μF，沒有發生短路故障。使用相同隔膜的額定電壓80V的混合型電解電容器ESR也較低為13~23mΩ，靜電容量為48~50μF，也沒有發生短路故障。 [0105] 實施例1~4的隔膜的壓縮保液率為162~289%。因此，本實施方式的隔膜的保液能力優良，能夠使電容器元件內的導電性高分子的保持量保持充足，可知在固態電解電容器以及混合型電解電容器中，有助於低ESR化。 [0106] 實施例5的隔膜是壓縮保液率為132%的隔膜。使用該隔膜的固態電解電容器以及混合型電解電容器，與實施例1~4相比，雖然靜電容量沒有差別，但是ESR略差。可認為這是因為，微細纖維的含有比例為0.0%，沒有作為對抗壓力的緩衝材料的效果。 [0107] 由此，可認為由於實施例5的隔膜的保液能力降低，電容器元件內的導電性高分子的保持量不充足，這會給電容器的ESR帶來一些影響。根據實施例1~4與實施例5的比較可知，如果隔膜中的微細纖維的含有比例為0.1%以上，則能夠進一步降低電容器的ESR。 [0108] 實施例6的隔膜是壓縮保液率為136%的隔膜。使用該隔膜的固態電解電容器以及混合型電解電容器，與實施例1~4相比，雖然靜電容量沒有差別，但是ESR略差。可認為這是因為，微細纖維的含有比例為8.6%，比實施例1~4高，因此隔膜的緻密性過高，纖維彼此間的間隙變小。 [0109] 因此，可認為由於隔膜的保液能力降低，所以電容器元件內的導電性高分子保持量不足，這會給電容器的ESR帶來一些影響。根據實施例1~4與實施例6的比較可知，如果隔膜中的微細纖維的含有比例為8.0%以下，則能夠進一步降低電容器的ESR。 [0110] 比較例1的隔膜與專利文獻1的實施例1中記載的隔膜相同，壓縮保液率為105%。因此，與使用各實施例的隔膜的電容器的評價結果相比，雖然靜電容量沒有差別，但是ESR升高。可認為其原因是，由於含有30質量%的聚乙烯醇纖維，所以聚乙烯醇纖維預先佔據了纖維彼此間的間隙，即，保持導電性高分子的部分，因而隔膜的保液能力降低。 [0111] 由此可知，聚乙烯醇纖維之類的黏合纖維的含有量與壓縮保液率的降低相關，會影響電容器元件內的導電性高分子的保持量。因此，聚乙烯醇纖維之類的黏合纖維的含有量，如實施例4所示，如果為15質量%以下，則不會給壓縮保液率帶來不良影響。 [0112] 比較例2的隔膜，與專利文獻3的實施例1中記載的隔膜相同，微細纖維的含有比例為0.0%，壓縮保液率為124%。與使用各實施例的隔膜的電容器的評價結果相比，雖然靜電容量沒有差別，但是ESR升高。可認為其原因是，未延伸聚酯纖維較多為65質量%，纖維彼此黏著，因而預先佔據了纖維彼此間的間隙，即，保持導電性高分子的部分。由此可知，如果未延伸聚酯纖維的含有率為50質量%以下，則不會給壓縮保液率帶來不良影響。 [0113] 雖然比較例3的隔膜的厚度、密度、壓縮保液率與實施例水準相同，但是合成纖維的含有率為15質量%，比各實施例少。使用該比較例3的隔膜的額定電壓6.3V的固態電解電容器老化時的短路故障率為0.8%，比各實施例都高。另外，在額定電壓50V的固態電解電容器中也是老化時的短路故障率為0.7%，比各實施例都高。而且，在額定電壓16V的混合型電解電容器中也是老化時的短路故障率為0.8%，比各實施例都高，額定電壓80V的混合型電解電容器也是老化時的短路故障率為0.7%，比各實施例都高。 [0114] 可認為其原因是，比較例3的隔膜在隔膜整體中僅含有15質量%的合成纖維，導電性高分子的聚合液、分散液使得隔膜的機械強度降低。由此可知，為了降低電容器的短路故障率，合成纖維的含有率為15質量%是不夠的，需要為20質量%以上。 [0115] 雖然比較例4的隔膜的厚度、密度、微細纖維的含有比例與實施例水準相同，但是壓縮保液率為104%。對於該壓縮保液率，使用比較例4的隔膜的各電容器的ESR均升高。在各實施例、各參考例中，在壓縮保液率小於130%的情況下，無法降低電容器的ESR。 [0116] 因此，根據比較例1、2、4與各實施例的比較可知，為了降低ESR，需要使隔膜的壓縮保液率為130%以上。 [0117] 現有例的隔膜雖然與專利文獻2的實施例1中記載的隔膜相同，但是微細纖維的含有比例非常高為16.2%，壓縮保液率較低為88%。因此，在各電容器的評價中，靜電容量略低，ESR升高。可認為這是因為，現有例的隔膜的微細纖維的含有比例非常高，隔膜的緻密性過高，纖維彼此間的間隙變小。因此，可認為對導電性高分子的聚合液、分散液的保液能力降低。 [0118] 各實施例、各參考例、現有例中，雖然吸水速度最快的是實施例5，但是固態電解電容器以及混合型電解電容器的各額定電壓的ESR最低的是實施例3。 [0119] 同樣地，各實施例、各參考例、現有例中，雖然橫向的吸液度最高的是實施例1，但是固態電解電容器以及混合型電解電容器的各額定電壓的ESR最低的是實施例3。 [0120] 根據壓縮保液率最高的為實施例3可知，與隔膜的吸水速度以及吸液度相比，對電容器的ESR降低產生最大影響的是保液性。 [0121] 進一步，通過採用確保壓縮保液率的結構，能夠測量在被施加負載的環境下的隔膜的保液能力，能夠將其用作觀察電容器的特性的指標。 [0122] 以上所述的本實施方式的隔膜，是保液能力提高的隔膜，通過在電容器中使用該隔膜，能夠降低ESR，進一步，還有助於減少短路故障。進一步，還存在該隔膜能夠有助於電容器的生產率的提高和製造成本的降低的可能性。[0022] Hereinafter, an embodiment of the present invention will be described in detail. In the example of the embodiment of the present invention, attention is paid to the liquid retaining ability of the diaphragm, and a configuration capable of securing a predetermined liquid retention rate or more is employed. [0023] When a separator is sandwiched between a pair of electrodes and wound to form a capacitor element, the separator is in a state of being compressed by the two electrode foils. In the case of a separator having a high wettability, although it is effective for shortening the wetting time or the like, in such a compressed state, the amount of the conductive polymer to be held may not be increased. Therefore, in the example of the present embodiment, the wettability such as the liquid absorption and the water absorption are not selected, but the state in which the capacitor element is formed is assumed, and a configuration capable of securing a predetermined compression liquid retention rate is adopted. That is, the separator of the present embodiment is a separator for an aluminum electrolytic capacitor inserted between a pair of electrodes, and the separator has a compressed liquid retention ratio of 130% or more. The compressed liquid retention ratio is preferably 160% or more, and more preferably 190% or more. There is no particular upper limit for the compression liquid retention rate of the separator. However, it is considered that the upper limit is about 300%, based on the thickness and density of the separator which can be applied to an actual capacitor. [0025] In the separator of the example of the present embodiment, the ESR can be reduced by making the compression liquid retention rate 130% or more. This is because when the compressed liquid retention rate is less than 130% of the liquid holding ability, there is a case where the ESR cannot be sufficiently reduced. [0026] The term "compressed liquid retention rate" as used herein refers to a liquid retention ratio calculated by immersing a separator in ethanol and then compressing it, and calculating the difference between the mass in the dry state and the mass after compression. An indicator for measuring the performance of a diaphragm. [0027] Specifically, the mass of the dry state of the separator of a certain area is measured, and thereafter, the separator is immersed in ethanol and taken out, and the separator is 7 kN/m. 2 After the pressurization, the mass was measured, and the compression liquid retention rate was calculated from the difference between the mass in the dry state and the mass after compression. In the case of the compressed liquid retention rate, it is possible to investigate the liquid holding ability of the separator holding the liquid after the load is applied, and it can be used as an index for appropriately measuring the liquid holding ability of the separator after the element is wound. It should be noted that in order to completely impregnate the separator test piece with ethanol, the immersion time was selected to be 30 seconds. [0028] In the present embodiment, the reason for paying attention to the wettability of the separator and paying attention to the liquid retention ability is that when the wettability of the separator is good, the polymerization liquid and the dispersion of the conductive polymer are well wetted, and the capacitor is immersed. The capacity performance rate is improved and the ESR is also improved. However, as described above, further low ESR is required in recent years. In response to this demand, it is known that not only the evaluation of wettability is important, but also the liquid retention ability is important. If it is 7kN/m stronger than the load applied to the diaphragm after the component is wound 2 After the pressure is applied, the separator having a compressed liquid retention rate of 130% or more can be said to be a separator having a high liquid retention capability. Therefore, when the liquid retention ability is increased, the conductive polymer can be formed on the surface of the capacitor electrode foil and even at the corners between the electrode foils, and the ESR characteristics can be improved. [0030] According to the present embodiment, by selecting a separator having a high liquid retention capability, the separator can sufficiently hold the polymerization liquid and the dispersion liquid of the conductive polymer, and the amount of the conductive polymer retained is also increased. In addition, when the separator contains 20% by mass or more of synthetic fibers, the acid resistance and oxidation resistance of the separator are improved, and the mechanical strength of the separator due to the polymerization liquid or the dispersion of the conductive polymer can be prevented from being lowered. [0031] When the content of the synthetic fiber is less than 20% by mass, that is, when the content of the natural fiber such as cellulose fiber exceeds 80% by mass, the acid resistance and oxidation resistance of the separator are lowered, and the mechanical mechanism of the separator The strength is reduced, so the short-circuit failure rate of the capacitor is increased. The synthetic fiber used in the example of the present embodiment is preferably a nylon fiber, an aramid fiber, an acrylic fiber, or a polyester fiber from the viewpoint of acid resistance and oxidation resistance of the separator. [0033] These synthetic fibers may be used alone or in combination of two or more. Among these synthetic fibers, a polyamide fiber such as a nylon fiber is more preferable from the viewpoint of affinity for a polymerization liquid or a dispersion of a conductive polymer. Further, these synthetic fibers may be fibrillated fibers or non-fibrillated fibers. In addition, in the case of a polyester fiber (hereinafter referred to as "unstretched polyester fiber") which is produced by avoiding elongation, it is advantageous in that the mechanical strength of the separator is improved due to the adhesion of the fibers to the interlacing point. Physical properties. The content of the unstretched polyester fiber is not particularly limited as long as it can satisfy the required compression liquid retention rate, but if it is about 50% by mass, the compression liquid retention rate is hard to be lowered. [0035] The separator of the example of the present embodiment may contain 20% by mass or more of synthetic fibers, and the other fibers constituting the separator are preferably fibers other than synthetic fibers, and are not limited. In the case of synthetic fibers, fibers other than the above may be used, and in the case of fibers other than synthetic fibers, natural fibers such as cellulose may also be used. Further, in consideration of mechanical strength during molding of the separator, winding, and the like, an adhesive fiber such as polyvinyl alcohol fiber can be used in a range that does not affect the compression liquid retention rate. The content of the binder fiber is not particularly limited as long as it can satisfy the required compression liquid retention rate, but if it is about 15% by mass, the compression liquid retention rate is hard to be lowered. When the content ratio of the fine fibers of the separator is in the range of 0.1 to 8.0%, the fluid retention rate of the separator can be increased, and the liquid retention ability can be improved. Although the details are not known, it is considered that the fine fibers are appropriately dispersed in a state in which the content of the fine fibers is 0.1 to 8.0%, and it acts as a cushioning material against compression. That is to say, it can be considered that the diaphragm has resistance to compression, can maintain thickness, and does not reduce the liquid retention ability. [0038] The fine fibers in the present embodiment mean fibers having a fiber length of 0.05 mm or more and less than 0.2 mm. As a method of obtaining the fine fibers, for example, a method generally used for preparing a papermaking raw material may be used, and a beater, a conical refiner, a disc refiner, a high pressure homogenizer, or the like can be generally used. [0039] Fibers having a fiber length of less than 0.05 mm may flow out when the sheet is formed. Further, in the case of fibers of 0.2 mm or more, since the fibers are entangled with each other, they do not become in an appropriate dispersed state in the separator, and do not function as a cushioning material. When the content ratio of the fine fibers is less than 0.1%, the effect of the action of the fine fibers as a cushioning material is lowered, and it is difficult to withstand the pressurization, and the liquid retaining ability of the separator may be lowered. Further, when the content ratio of the fine fibers exceeds 8.0%, the separator is too dense, and the gap between the fibers becomes small. Therefore, there is a case where the liquid holding ability of the separator cannot be exhibited. The thickness and density of the separator of the present embodiment are not particularly limited, and a thickness and a density satisfying the characteristics of the required aluminum electrolytic capacitor can be employed. Generally, the thickness is 20~70μm and the density is 0.20~0.60g/cm. 3 The left and right diaphragms are not limited to this range. [0042] In an embodiment of the invention, the separator is a wet nonwoven fabric formed using a papermaking method. The papermaking method of the separator is not particularly limited as long as it can satisfy the compression liquid retention ratio or the content ratio of the fine fibers, and a papermaking method such as long-net papermaking, short-web papermaking, or round-web papermaking can be used, or a plurality of papermaking methods can be used. A separator obtained by a layer formed by these papermaking methods. In addition, at the time of papermaking, an additive such as a dispersing agent, an antifoaming agent, or a paper strength enhancer may be added as long as it is an impurity content which does not affect the separator for a capacitor, or may be formed after the paper layer is formed. Paper strength enhancement processing, lyophilic processing, calender processing, embossing processing, etc. [0044] By adopting the above configuration, the separator of the present embodiment forms a uniform electron conduction path or contributes to an increase in the amount of retention of the conductive polymer. Further, by using the separator for an aluminum electrolytic capacitor using a conductive polymer as a cathode material, an aluminum electrolytic capacitor having a low ESR can be obtained. In the aluminum electrolytic capacitor of the present embodiment, a separator having the above configuration is used as a separator, and the separator is inserted between a pair of electrodes, and a conductive polymer is used as a cathode material. (Measurement Method of Characteristics of Separator and Aluminum Electrolytic Capacitor) Specific measurement of each characteristic of the separator and the aluminum electrolytic capacitor of the present embodiment was carried out in accordance with the following conditions and methods. (Canadian Standard Water Filtration (CSF)) in accordance with JIS P8121-2 Pulp-Water Filtration Test Method - Part 2: Canadian Standard Water Filtration Method (ISO5267-2 "Pulps-Determination of drainability- Part 2: "Canadian Standard" freeness method")", measuring CSF. (Thickness) "JIS C 2300-2 "Cellose paper for electrical use - Part 2: Test method" 5.1 Thickness", "5.1.1 Measuring tool and measuring method a When using an external micrometer" The micrometer is measured by folding into 10 sheets in accordance with "5.1.3 Measuring the thickness of folded paper". (Density) The density of the separator in an absolutely dry state was measured in accordance with the method defined by the B method of "JIS C 2300-2 "Cellulose paper for electrical use - Part 2: Test method" 7.0A density". (Content ratio of fine fibers) The content ratio of the fine fibers is "JIS P 8226-2 "Method for measuring fiber length of pulp-optical automatic analysis method - Part 2: Unpolarized light method" (ISO16065-2) The device described in "Pulps-Determination of Fiber length by automated optical analysis-Part 2: Unpolarized light method"), where kjaani Fiber Lab (manufactured by Metso Automation Co., Ltd.) is used to measure the length-weighted average in the range of 0.05 to 7.6 mm. The fiber length distribution was calculated for the content ratio of the fine fibers having a fiber length of 0.05 mm or more and less than 0.2 mm. (Compression Liquid Hold Rate) The mass of the separator before impregnation was measured. In addition, the separator was immersed in ethanol at 20 ° C for 30 seconds at 7 kN/m. 2 After the pressurization, the mass was measured, and the compressed liquid retention ratio was calculated by the following formula 1. It should be noted that the measurement was carried out in an environment of room temperature of 20 ° C and a relative humidity of 65%. Compressed liquid retention rate (%) = [(W2-W1) / W1] × 100 (Formula 1) W1: Test piece mass before impregnation (g) W2: Test piece mass after pressurization (g) [0052] ( Water absorption rate) The water absorption rate is measured by the method specified in the B method of "JIS C 2300-2 "Electrical cellulose paper - Part 2: Test method" 22 water absorption", and the water absorbed in 1 minute is measured. The height is taken as the water absorption speed (mm/min). Although the diaphragm width is 20 mm in Patent Document 2, the measurement is performed in accordance with the width described in JIS. (Water absorption in the lateral direction) The liquid absorbance is used as an index of the wettability of the separator. It is considered that when the liquid absorption is increased, the wettability of the separator becomes high. In addition, the measurement of the liquid absorption is carried out by changing the water to ethanol using the method specified in the B method of "JIS C 2300-2 "Cellose paper for electrical use - Part 2: Test method" 22 water absorption". . In addition, considering the wetting step of the capacitor, the direction of the liquid absorbing is selected from the lateral direction of the separator. (Production Step of Solid Electrolytic Capacitor) Using the separators of the respective examples, comparative examples, and conventional examples, a solid electrolytic capacitor having a rated voltage of 6.3 V, a diameter of 10.0 mm, and a height of 10.0 mm, and a rated voltage of 50 V and a diameter of 10.0 mm were produced. × Solid electrolytic capacitor with a height of 15.0 mm. [0055] The specific production method is as follows. The anode foil and the cathode foil which were subjected to the etching treatment and the oxide film formation treatment were inserted into the separator and wound, and the capacitor element was produced. The fabricated capacitor element was dried after being chemically converted again. In the case of a solid electrolytic capacitor having a rated voltage of 6.3 V, the capacitor element is impregnated with the conductive polymer polymerization liquid, and then heated/polymerized, and the solvent is dried to form a conductive polymer. In the case of a solid electrolytic capacitor having a rated voltage of 50 V, the capacitor element is wetted with the conductive polymer aqueous dispersion, and then heated/dried to form a conductive polymer. Next, the capacitor element was placed in a predetermined casing, and the opening was closed, and then aged to obtain two types of solid electrolytic capacitors having different rated voltages. (Production Procedure of Hybrid Electrolytic Capacitor) A hybrid electrolytic capacitor having a rated voltage of 16 V, a diameter of 10.0 mm, and a height of 12.5 mm was produced using the separators of the respective Examples, Comparative Examples, and Conventional Examples, and a rated voltage of 80 V and a diameter of 10.0 mm. × Hybrid electrolytic capacitor with a height of 10.5 mm. [0058] The specific production method is as follows. The anode foil and the cathode foil which were subjected to the etching treatment and the oxide film formation treatment were inserted into the separator and wound, and the capacitor element was produced. The fabricated capacitor element was dried after being chemically converted again. In the case of a hybrid electrolytic capacitor having a rated voltage of 16 V, the capacitor element is wetted with the conductive polymer polymerization liquid, and then heated/polymerized, and the solvent is dried to form a conductive polymer. In the case of a hybrid electrolytic capacitor having a rated voltage of 80 V, the capacitor element is wetted with the conductive polymer dispersion, and then heated/dried to form a conductive polymer. Then, the capacitor element is wetted with the driving electrolyte solution, the capacitor element is placed in a predetermined casing, and the opening is closed, and then aged to obtain two types of hybrid electrolytic capacitors having different rated voltages. (Evaluation Method of Aluminum Electrolytic Capacitor) The specific performance evaluation of the aluminum electrolytic capacitor of the present embodiment was carried out in accordance with the following conditions and methods. (ESR) The ESR of the fabricated capacitor element was measured using an LCR meter at a temperature of 20 ° C and a frequency of 100 kHz. (Electrostatic Capacitance) The capacitance was determined in accordance with the method of "4.7 Electrostatic Capacity" defined in "JIS C 5101-1 "Fixed Capacitors for Electronic Equipment - Part 1: Item Category General". [Short-circuit failure rate] The short-circuit failure rate is the number of short-circuit faults occurring during aging using a wound capacitor element, and the number of components of the short-circuit fault is divided by the number of capacitor elements subjected to aging, and the short circuit is expressed as a percentage. failure rate. (Examples, etc.) Hereinafter, specific examples and the like of the separator of the embodiment of the present invention will be described. (Example 1) 20% by mass of semi-aromatic nylon fibers and 80% by mass (CSF 500 ml) of fibrillated cellulose fibers were mixed. The obtained raw material was subjected to round papermaking to obtain the separator of Example 1. The separator has a thickness of 50 μm and a density of 0.60 g/cm. 3 The compressed liquid retention rate was 162%, the water absorption speed was 25 mm/min, the lateral liquid absorption was 26 mm/(10 minutes), and the content of the fine fibers was 0.1%. (Example 2) 20% by mass of acrylic fiber, 10% by mass of polyester fiber, and 70% by mass (CSF of 30 ml) of fibrillated aramid fiber were mixed. The obtained raw material was subjected to round paper making to obtain the separator of Example 2. The separator has a thickness of 40 μm and a density of 0.30 g/cm. 3 The compressed liquid retention rate was 221%, the water absorption speed was 16 mm/min, the lateral liquid absorption was 6 mm/(10 minutes), and the content of the fine fibers was 7.7%. (Example 3) 75 mass% of semi-aromatic nylon fibers, 20 mass% (CSF 110 ml) of fibrillated cellulose fibers, and 5% by mass of polyvinyl alcohol fibers were mixed. The obtained raw material was subjected to round-web papermaking to obtain the separator of Example 3. The separator has a thickness of 70 μm and a density of 0.20 g/cm. 3 The compressed liquid retention rate was 289%, the water absorption speed was 9 mm/min, the lateral liquid absorption was 12 mm/(10 minutes), and the content of the fine fibers was 3.6%. (Example 4) 40% by mass of aramid fiber, 45 mass% (CSF 210 ml) of fibrillated cellulose fiber, and 15% by mass of polyvinyl alcohol fiber were mixed. The obtained raw material was subjected to round-web papermaking to obtain the separator of Example 4. The separator has a thickness of 20 μm and a density of 0.40 g/cm. 3 The compressed liquid retention rate was 191%, the water absorption speed was 4 mm/min, the lateral liquid absorption was 20 mm/(10 minutes), and the content of the fine fibers was 0.8%. (Example 5) 30% by mass of semi-aromatic nylon fibers, 20% by mass of acrylic fibers, and 50% by mass of unstretched polyester fibers were mixed. The obtained raw material was subjected to round-web papermaking to obtain the separator of Example 5. The separator has a thickness of 30 μm and a density of 0.50 g/cm. 3 The compressed liquid retention rate was 132%, the water absorption speed was 33 mm/min, the lateral liquid absorption was 24 mm/(10 minutes), and the content of the fine fibers was 0.0%. (Example 6) 65 mass% of acrylic fiber, and 35 mass% (CSF20 ml) of fibrillated acrylic fiber were mixed. The obtained raw material was subjected to round papermaking to obtain the separator of Example 6. The separator has a thickness of 50 μm and a density of 0.30 g/cm. 3 The compressed liquid retention rate was 136%, the water absorption speed was 11 mm/min, the lateral liquid absorption was 9 mm/(10 minutes), and the content of the fine fibers was 8.6%. (Comparative Example 1) A separator was produced in the same manner as in the method described in Example 1 of Patent Document 1, and this was used as the separator of Comparative Example 1. The separator of Comparative Example 1 contained 70% by mass of semi-aromatic nylon fibers and 30% by mass of polyvinyl alcohol fibers, and had a thickness of 40 μm and a density of 0.27 g/cm. 3 The compressed liquid retention rate was 105%, the water absorption speed was 3 mm/min, the lateral liquid absorption was 14 mm/(10 minutes), and the content of the fine fibers was 0.0%. (Comparative Example 2) A separator was produced in the same manner as in the method described in Example 1 of Patent Document 3, and this was used as a separator of Comparative Example 2. The separator of Comparative Example 2 contained 35% by mass of polyester fiber and 65% by mass of unstretched polyester fiber, and had a thickness of 50 μm and a density of 0.40 g/cm. 3 The compression liquid retention rate was 124%, the water absorption speed was 14 mm/min, the lateral liquid absorption was 19 mm/(10 minutes), and the microfiber content was 0.0%. (Comparative Example 3) 15% by mass of semi-aromatic nylon fibers and 85% by mass (CSF 400 ml) of fibrillated cellulose fibers were mixed. The obtained raw material was subjected to round-web papermaking to obtain a separator of Comparative Example 3. The separator has a thickness of 60 μm and a density of 0.40 g/cm. 3 The compressed liquid retention rate was 139%, the water absorption speed was 28 mm/min, the lateral liquid absorption was 24 mm/(10 minutes), and the content of the fine fibers was 1.0%. (Comparative Example 4) 15% by mass of acrylic fibers, 25% by mass of polyester fibers, and 60% by mass (CSF of 200 ml) of fibrillated aramid fibers were mixed. The obtained raw material was subjected to round-web papermaking to obtain a separator of Comparative Example 4. The separator has a thickness of 50 μm and a density of 0.30 g/cm. 3 The compressed liquid retention rate was 104%, the water absorption speed was 12 mm/min, the lateral liquid absorption was 16 mm/(10 minutes), and the microfiber content was 4.3%. (Conventional Example) A separator was produced in the same manner as the method described in Example 1 of Patent Document 2, and used as a separator of the conventional example. The separator of the prior art contains 30% by mass (CSF 12 ml) of fibrillated aramid fiber, 45% by mass of polyester fiber, and 25% by mass of unstretched polyester fiber, having a thickness of 45 μm and a density of 0.35 g/cm. 3 The compressed liquid retention rate was 88%, the water absorption speed was 10 mm/min, the lateral liquid absorption was 6 mm/(10 minutes), and the content of the fine fibers was 16.2%. The evaluation results of the individual individuals of the examples, the comparative examples, and the conventional examples of the present embodiment are shown in Table 1. In addition, Table 1 also includes water absorption speed and lateral liquid absorption. [0078] The performance evaluation results of the aluminum electrolytic capacitors produced using the separators of the respective examples, the respective comparative examples, and the conventional examples are shown in Table 2. As shown in Table 2, as a solid electrolytic capacitor, a capacitor having a rated voltage of 6.3 V for low voltage and a capacitor having a rated voltage of 50 V for high voltage were fabricated. Further, as a hybrid electrolytic capacitor, a capacitor having a rated voltage of 16 V for low voltage and a capacitor having a rated voltage of 80 V for high voltage were fabricated. [0080] (Solid Electrolytic Capacitor Using the Separator of Example 1) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 1 had an ESR of 16 mΩ, an electrostatic capacity of 269 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 18 mΩ, an electrostatic capacity of 40 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 1) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 1 had an ESR of 19 mΩ, an electrostatic capacity of 129 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 23 mΩ, an electrostatic capacitance of 50 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Example 2) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 2 had an ESR of 10 mΩ, an electrostatic capacity of 260 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 12 mΩ, an electrostatic capacity of 38 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 2) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 2 had an ESR of 14 mΩ, an electrostatic capacity of 125 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 17 mΩ, an electrostatic capacitance of 48 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Example 3) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 3 had an ESR of 8 mΩ, an electrostatic capacity of 263 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 9 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 3) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 3 had an ESR of 10 mΩ, an electrostatic capacity of 126 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 13 mΩ, an electrostatic capacity of 49 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Example 4) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 4 had an ESR of 13 mΩ, an electrostatic capacitance of 267 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50 V has an ESR of 14 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 4) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 4 had an ESR of 16 mΩ, an electrostatic capacitance of 128 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 19 mΩ, an electrostatic capacitance of 49 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Example 5) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 5 had an ESR of 19 mΩ, an electrostatic capacitance of 269 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 22 mΩ, an electrostatic capacity of 40 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 5) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 5 had an ESR of 24 mΩ, an electrostatic capacitance of 130 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 28 mΩ, an electrostatic capacitance of 50 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Example 6) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Example 6 had an ESR of 18 mΩ, an electrostatic capacity of 263 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50 V has an ESR of 21 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Example 6) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Example 6 had an ESR of 23 mΩ, an electrostatic capacity of 126 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 27 mΩ, an electrostatic capacitance of 48 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Comparative Example 1) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 1 had an ESR of 26 mΩ, an electrostatic capacity of 264 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 31 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Comparative Example 1) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 1 had an ESR of 31 mΩ, an electrostatic capacity of 127 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 38 mΩ, an electrostatic capacity of 49 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Comparative Example 2) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 2 had an ESR of 24 mΩ, an electrostatic capacity of 269 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 28 mΩ, an electrostatic capacity of 40 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Comparative Example 2) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 2 had an ESR of 30 mΩ, an electrostatic capacitance of 129 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 35 mΩ, an electrostatic capacitance of 50 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of Comparative Example 3) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 3 had an ESR of 17 mΩ, an electrostatic capacitance of 269 μF, and a short-circuit failure rate of 0.8%. The solid electrolytic capacitor with a rated voltage of 50 V has an ESR of 20 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0.7%. (Hybrid Electrolytic Capacitor Using the Separator of Comparative Example 3) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 3 had an ESR of 21 mΩ, an electrostatic capacitance of 129 μF, and a short-circuit failure rate of 0.8%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 25 mΩ, an electrostatic capacity of 50 μF, and a short-circuit failure rate of 0.7%. (Solid Electrolytic Capacitor Using the Separator of Comparative Example 4) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 4 had an ESR of 27 mΩ, an electrostatic capacity of 266 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50 V has an ESR of 32 mΩ, an electrostatic capacity of 39 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of Comparative Example 4) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of Comparative Example 4 had an ESR of 32 mΩ, an electrostatic capacity of 128 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 39 mΩ, an electrostatic capacitance of 49 μF, and a short-circuit failure rate of 0%. (Solid Electrolytic Capacitor Using the Separator of the Conventional Example) The solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of the prior art has an ESR of 34 mΩ, an electrostatic capacitance of 250 μF, and a short-circuit failure rate of 0%. The solid electrolytic capacitor with a rated voltage of 50V has an ESR of 38 mΩ, an electrostatic capacity of 37 μF, and a short-circuit failure rate of 0%. (Hybrid Electrolytic Capacitor Using the Separator of the Conventional Example) The hybrid electrolytic capacitor having a rated voltage of 16 V using the separator of the prior art has an ESR of 35 mΩ, an electrostatic capacity of 120 μF, and a short-circuit failure rate of 0%. The hybrid electrolytic capacitor with a rated voltage of 80 V has an ESR of 42 mΩ, an electrostatic capacity of 46 μF, and a short-circuit failure rate of 0%. As described above, the solid electrolytic capacitors having the rated voltage of 6.3 V of the separators of Examples 1 to 4 had a low ESR of 8 to 16 mΩ and an electrostatic capacity of 260 to 269 μF, and no short-circuit failure occurred. The ESR of a solid electrolytic capacitor with a rated voltage of 50 V using the same diaphragm is also as low as 9 to 18 mΩ, and has an electrostatic capacity of 38 to 40 μF, and no short-circuit failure occurs. Further, in the evaluation of the hybrid electrolytic capacitor having the rated voltage of 16 V of the separators of Examples 1 to 4, the ESR was as low as 10 to 19 mΩ, and the electrostatic capacity was 125 to 129 μF, and no short-circuit failure occurred. The ESR of the hybrid electrolytic capacitor using the same diaphragm with a rated voltage of 80 V is also as low as 13 to 23 mΩ, and the electrostatic capacity is 48 to 50 μF, and no short-circuit failure occurs. [0105] The separators of Examples 1 to 4 had a compressed liquid retention ratio of 162 to 289%. Therefore, the separator of the present embodiment is excellent in the liquid holding ability, and the amount of the conductive polymer held in the capacitor element can be kept sufficiently. It is understood that the solid electrolytic capacitor and the hybrid electrolytic capacitor contribute to low ESR. The separator of Example 5 was a separator having a compressed liquid retention rate of 132%. The solid electrolytic capacitor and the hybrid electrolytic capacitor using the separator have slightly worse ESR than those of Examples 1 to 4, but the ESR is slightly inferior. This is considered to be because the content ratio of the fine fibers is 0.0%, and there is no effect as a cushioning material against pressure. Thus, it is considered that the liquid retaining ability of the separator of Example 5 is lowered, and the amount of the conductive polymer held in the capacitor element is insufficient, which causes some influence on the ESR of the capacitor. According to the comparison between Examples 1 to 4 and Example 5, when the content ratio of the fine fibers in the separator is 0.1% or more, the ESR of the capacitor can be further reduced. The separator of Example 6 was a separator having a compression retention ratio of 136%. The solid electrolytic capacitor and the hybrid electrolytic capacitor using the separator have slightly worse ESR than those of Examples 1 to 4, but the ESR is slightly inferior. This is considered to be because the content ratio of the fine fibers is 8.6%, which is higher than those of Examples 1 to 4. Therefore, the denseness of the separator is too high, and the gap between the fibers is small. Therefore, it is considered that since the liquid retaining ability of the separator is lowered, the amount of the conductive polymer held in the capacitor element is insufficient, which causes some influence on the ESR of the capacitor. According to the comparison between Examples 1 to 4 and Example 6, it is understood that when the content ratio of the fine fibers in the separator is 8.0% or less, the ESR of the capacitor can be further reduced. The separator of Comparative Example 1 was the same as the separator described in Example 1 of Patent Document 1, and the compressed liquid retention ratio was 105%. Therefore, compared with the evaluation results of the capacitor using the separator of each embodiment, although there is no difference in electrostatic capacitance, the ESR is increased. The reason for this is considered to be that since the polyvinyl alcohol fibers are contained in an amount of 30% by mass, the polyvinyl alcohol fibers occupy a gap between the fibers in advance, that is, a portion in which the conductive polymer is held, and thus the liquid retaining ability of the separator is lowered. From this, it is understood that the content of the binder fiber such as the polyvinyl alcohol fiber is related to the decrease in the compression liquid retention rate, and affects the amount of the conductive polymer held in the capacitor element. Therefore, the content of the binder fiber such as polyvinyl alcohol fiber is not more than 15% by mass as shown in Example 4, and does not adversely affect the compression liquid retention rate. The separator of Comparative Example 2 is the same as the separator described in Example 1 of Patent Document 3, and the content ratio of the fine fibers is 0.0%, and the compression liquid retention rate is 124%. The ESR was increased although there was no difference in electrostatic capacitance as compared with the evaluation results of the capacitor using the separator of each of the examples. The reason for this is considered to be that the unstretched polyester fibers are mostly 65% by mass, and the fibers are adhered to each other, so that the gap between the fibers, that is, the portion of the conductive polymer, is occupied in advance. From this, it is understood that when the content of the unstretched polyester fiber is 50% by mass or less, the compression and liquid retention rate is not adversely affected. Although the thickness, density, and compression retention ratio of the separator of Comparative Example 3 were the same as those of the examples, the content of the synthetic fibers was 15% by mass, which was less than that of the respective examples. The short-circuit failure rate at the time of aging of the solid electrolytic capacitor having a rated voltage of 6.3 V using the separator of Comparative Example 3 was 0.8%, which was higher than that of the respective examples. Further, in the solid electrolytic capacitor having a rated voltage of 50 V, the short-circuit failure rate at the time of aging was also 0.7%, which was higher than that of the respective examples. Further, in the hybrid electrolytic capacitor having a rated voltage of 16 V, the short-circuit failure rate at the time of aging is 0.8%, which is higher than that of the respective embodiments, and the hybrid electrolytic capacitor having a rated voltage of 80 V is also a short-circuit failure rate at the time of aging of 0.7%. Each embodiment is high. The reason for this is that the separator of Comparative Example 3 contains only 15% by mass of synthetic fibers in the entire separator, and the polymerization liquid or dispersion of the conductive polymer lowers the mechanical strength of the separator. From this, it is understood that in order to reduce the short-circuit failure rate of the capacitor, the content of the synthetic fiber is not sufficient, and it is necessary to be 20% by mass or more. Although the thickness, density, and content ratio of the fine fibers of the separator of Comparative Example 4 were the same as those of the examples, the compression liquid retention ratio was 104%. With respect to the compressed liquid retention rate, the ESR of each of the capacitors using the separator of Comparative Example 4 was increased. In each of the examples and the respective reference examples, when the compression liquid retention rate was less than 130%, the ESR of the capacitor could not be lowered. Therefore, according to the comparison of Comparative Examples 1, 2, and 4 with the respective examples, it is necessary to reduce the ESR of the separator to 130% or more in order to lower the ESR. The separator of the prior art is the same as the separator described in the first embodiment of Patent Document 2, but the content ratio of the fine fibers is very high at 16.2%, and the compression retention ratio is as low as 88%. Therefore, in the evaluation of each capacitor, the electrostatic capacitance was slightly lower and the ESR was increased. This is considered to be because the content of the fine fibers of the separator of the prior art is extremely high, the denseness of the separator is too high, and the gap between the fibers is small. Therefore, it is considered that the liquid retention ability of the polymerization liquid or the dispersion liquid of the conductive polymer is lowered. In each of the examples, the respective reference examples, and the conventional examples, the fifth embodiment is the fastest water absorption rate, but the ESR of the rated voltage of the solid electrolytic capacitor and the hybrid electrolytic capacitor is the lowest in the third embodiment. Similarly, in each of the examples, the respective reference examples, and the conventional examples, although the liquid absorption in the lateral direction is the highest in the first embodiment, the ESR of each of the rated voltages of the solid electrolytic capacitor and the hybrid electrolytic capacitor is the lowest. Example 3. According to Example 3, which has the highest compression retention ratio, it is known that liquid retention is most affected by the decrease in ESR of the capacitor as compared with the water absorption speed and the liquid absorption of the separator. Further, by adopting a configuration that ensures a compressed liquid retention rate, it is possible to measure the liquid retention capability of the separator in an environment in which a load is applied, and it can be used as an index for observing the characteristics of the capacitor. The separator of the present embodiment described above is a separator having improved liquid retention capability, and by using the separator in a capacitor, ESR can be reduced, and further, short-circuit failure can be reduced. Further, there is also a possibility that the separator can contribute to an increase in productivity of the capacitor and a reduction in manufacturing cost.