然而，實際上本發明人如專利文獻3般將市售之反丁烯二酸粉碎，並依據JIS K 5101-13-2(2004)測定其吸油量，結果為36.6 mL/100 g(參照下述比較例6)。市售之C4二羧酸之吸油量為25～30 mL/100 g左右(參照下述比較例1～5)，雖然粉碎C4二羧酸之吸油量超過該量，但因粉碎而未獲得充分之吸油量。 因此，本發明係關於提供一種吸油量較高之C4二羧酸結晶及其製造方法。 本發明人發現，於界面活性劑與高分子中，於選自特定之非離子性界面活性劑、非離子性高分子、陽離子性高分子及兩性高分子中之1種以上之存在下，自含有C4二羧酸或其鹽之水溶液進行晶析而獲得之C4二羧酸結晶具有前所未有之高吸油量。 本發明之C4二羧酸結晶具有高吸油量。因此，本發明之C4二羧酸結晶可更多地擔載油劑，而能夠適宜地用作沐浴劑等之原料。又，根據本發明之方法，能夠提高C4二羧酸結晶之吸油量，而獲得高吸油量之C4二羧酸結晶。 [C4二羧酸結晶] 關於本發明之C4二羧酸結晶，依據JIS K 5101-13-2(2004)所測得之吸油量為40 mL/100 g～200 mL/100 g。作為本發明中之C4二羧酸之例，可列舉：反丁烯二酸、琥珀酸、蘋果酸、酒石酸、順丁烯二酸、草醯乙酸等。較佳為反丁烯二酸或琥珀酸，更佳為反丁烯二酸。又，碳數為4之二羧酸或其鹽較佳為不具有胺基酸殘基者。 JIS K 5101-13-2(2004)係藉由煮亞麻籽油法所進行之吸油量之測定方法。測定方法之詳細內容記載於實施例中。於本說明書中，「依據JIS K 5101-13-2(2004)所測得之吸油量」亦簡稱為「吸油量」。 本發明之C4二羧酸結晶之吸油量為40 mL/100 g～200 mL/100 g，較佳為50 mL/100 g～200 mL/100 g，更佳為60 mL/100 g～200 mL/100 g，進而較佳為70 mL/100 g～200 mL/100 g。 [C4二羧酸結晶之製造方法] 本發明之C4二羧酸結晶亦可藉由包括如下步驟之方法而製造：於選自(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑、及(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑中之至少1種非離子性界面活性劑之存在下，自含有C4二羧酸或其鹽之水溶液析出C4二羧酸之結晶。 又，C4二羧酸結晶亦可藉由包括如下步驟之方法而製造：於選自(b1)非離子性高分子、(b2)陽離子性高分子、及(b3)兩性高分子中之至少1種高分子之存在下，自含有C4二羧酸或其鹽之水溶液析出C4二羧酸之結晶。 於本發明中，(a1)～(a2)之非離子性界面活性劑可單獨使用，又，亦可將複數個組合而使用。又，(b1)～(b3)之高分子可單獨使用，又，亦可將複數個組合而使用。於將複數個組合之情形時，亦可將(a1)～(a2)之非離子性界面活性劑與(b1)～(b3)之高分子組合而使用。非離子性界面活性劑與高分子只要於C4二羧酸結晶析出時存在即可，將該等添加至含有C4二羧酸或其鹽之水溶液中之時機並無特別限定。 (含有C4二羧酸或其鹽之水溶液) C4二羧酸(反丁烯二酸、琥珀酸、蘋果酸、酒石酸、順丁烯二酸、草醯乙酸等)或其鹽並無特別限定，可藉由源自苯或丁烷等石化原料之化學合成、或微生物醱酵而獲得。作為源自石化原料之化學合成之例，可列舉：藉由石化原料之氣相催化氧化等而獲得之順丁烯二酸酐或順丁烯二酸的異構化反應(反丁烯二酸)、還原反應、氫化反應(琥珀酸)、水合反應(蘋果酸)、藉由順丁烯二酸酐或順丁烯二酸之環氧化反應而獲得之環氧酒石酸的水合反應(酒石酸)等。 作為生成C4二羧酸或其鹽之微生物，可列舉根黴菌屬菌等絲狀菌。於藉由微生物醱酵而獲得C4二羧酸或其鹽之情形時，亦可自含有C4二羧酸或其鹽之培養液析出C4二羧酸之結晶。 (非離子性界面活性劑之HLB) 於本發明中，HLB係表示親水性-親油性之平衡(Hydrophile-Lipophile Balance)之指標，係根據小田、寺村等人之無機性值、有機性值所算出之數值。 根據無機性值、有機性值所算出之HLB具體而言係根據HLB＝(Σ無機性值/Σ有機性)×10而計算。此處，對於「無機性值」、「有機性值」之各者，例如對於分子中之1個碳原子，「有機性值」為20，對於分子中之1個羥基，「無機性值」為100，如此設定與各種原子或官能基對應之「無機性值」、「有機性值」(例如參照甲田善生著之「有機概念圖-基礎與應用-」11頁～17頁，三共出版1984年發行)，並累計有機化合物中之全部之原子及官能基之「無機性值」、「有機性值」，藉此算出該有機化合物之HLB。一般而言，非離子性界面活性劑之HLB為1～20之數值。 再者，於包含2種以上之非離子性界面活性劑之情形時之HLB如下式般係基於該調配質量比率將各非離子性界面活性劑之HLB相加並平均而算出者。 混合HLB＝Σ(HLBX
×WX
)/ΣWX
(式中，HLBX
表示非離子性界面活性劑X之HLB，WX
表示具有HLBX
之值之非離子性界面活性劑X之質量(g))。 (非離子性界面活性劑) 於本發明所使用之非離子性界面活性劑係選自(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑、及(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑中之至少1種。 作為(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑，例如可列舉：聚氧乙烯烷基醚、聚氧乙烯烯基醚、聚氧乙烯聚氧丙烯二醇、聚氧乙烯聚氧丙烯烷基醚、聚氧乙烯聚氧丙烯烯基醚、聚氧乙烯脂肪酸酯、聚氧乙烯甘油脂肪酸酯、聚氧乙烯山梨糖醇酐脂肪酸酯、聚氧乙烯山梨糖醇脂肪酸酯、聚氧乙烯蓖麻油、聚氧乙烯氫化蓖麻油等。 該等中，就晶析出高吸油量之C4二羧酸之觀點而言，較佳為選自聚氧乙烯烷基醚、聚氧乙烯山梨糖醇酐脂肪酸酯、聚氧乙烯山梨糖醇脂肪酸酯、聚氧乙烯蓖麻油、及聚氧乙烯氫化蓖麻油中之至少1種，更佳為選自聚氧乙烯烷基醚、聚氧乙烯山梨糖醇酐脂肪酸酯、及聚氧乙烯山梨糖醇脂肪酸酯中之至少1種，進而較佳為選自聚氧乙烯烷基醚及聚氧乙烯山梨糖醇脂肪酸酯中之至少1種。 又，聚氧乙烯鏈中之環氧乙烷加成莫耳數以平均值顯示，較佳為2以上，更佳為3以上，進而較佳為4以上，又，較佳為60以下，更佳為50以下，進而較佳為40以下，進而更佳為30以下，進而更佳為25以下，進而更佳為20以下。又，非離子性界面活性劑之脂肪酸部分、烷基部分及烯基部分之碳數較佳為6以上，更佳為8以上，進而較佳為10以上，又，較佳為24以下，更佳為22以下，進而較佳為20以下。 再者，所謂「具有聚氧乙烯鏈」係指於非離子性界面活性劑之分子中加成有1莫耳以上之環氧乙烷之結構。 (a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑的HLB就製造高吸油量之C4二羧酸之結晶之觀點而言，較佳為1以上，更佳為4以上，進而較佳為5以上。 作為(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑的種類，可列舉：聚甘油脂肪酸酯、甘油脂肪酸酯、乙二醇脂肪酸酯、丙二醇脂肪酸酯、丁二醇脂肪酸酯、山梨糖醇酐脂肪酸酯、蔗糖脂肪酸酯、烷基葡糖苷等。該等中，就製造高吸油量之C4二羧酸之結晶之觀點而言，較佳為選自山梨糖醇酐脂肪酸酯及烷基葡糖苷中之至少1種。 (a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑的HLB就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為4以上，更佳為8以上，進而較佳為10以上，又，較佳為13以下。 (a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑的HLB較佳為4以上且未達15，更佳為8以上且13以下，進而較佳為10以上且13以下。 非離子性界面活性劑可使用商業上獲得者。 (非離子性界面活性劑之含量) 於析出C4二羧酸之結晶時之非離子性界面活性劑之濃度就使高吸油量之C4二羧酸結晶化之觀點而言，於含有C4二羧酸或其鹽之水溶液中，較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，就發泡等工業操作性、成本之觀點而言，較佳為5質量%以下，更佳為1.5質量%以下，進而較佳為1質量%以下。 含有C4二羧酸或其鹽之水溶液中之非離子性界面活性劑之含量較佳為0.001質量%以上且5質量%以下，更佳為0.01質量%以上且1.5質量%以下，進而較佳為0.05質量%以上且1質量%以下。 又，於本發明中，含有C4二羧酸或其鹽之水溶液中之非離子性界面活性劑之含量相對於C4二羧酸之含量(C4二羧酸之含量與C4二羧酸鹽中之C4二羧酸之含量的和)的比(質量比)就製造高吸油量之C4二羧酸結晶之觀點而言，較佳為0.001～0.5，更佳為0.002～0.3，進而較佳為0.01～0.3。 (高分子) 本發明中所使用之高分子係選自(b1)非離子性高分子、(b2)陽離子性高分子、及(b3)兩性高分子中之至少1種。該等高分子較佳為水溶性。 作為(b1)非離子性高分子，可為水溶性合成高分子、水溶性半合成高分子、水溶性天然高分子中之任一者。作為非離子性高分子，例如可列舉：澱粉系高分子(例如羧甲基澱粉、可溶性澱粉、甲基澱粉等)、纖維素系高分子(例如甲基纖維素、乙基纖維素等烷基纖維素，羥乙基纖維素、羥丙基甲基纖維素等羥烷基纖維素等)、乙烯基系高分子(例如聚乙烯醇、聚乙烯吡咯啶酮、聚乙烯甲醚等)、聚伸烷基二醇等。 非離子性高分子就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為使具有乙烯基之單體聚合而成之乙烯基系高分子或羥烷基纖維素，更佳為聚乙烯醇或羥乙基纖維素。 作為(b2)陽離子性高分子，可列舉：陽離子化纖維素、陽離子化澱粉、陽離子化瓜爾膠、聚伸乙基亞胺系聚合物、雙氰胺系高分子、二烯丙基胺系聚合物等。 陽離子性高分子就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為陽離子化纖維素。 作為(b3)兩性高分子，可列舉：甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸共聚物、甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸硬脂酯共聚物、甲基丙烯酸乙基甜菜鹼-丙烯酸共聚物、苯乙烯-丙烯酸-丙烯酸二烷基胺基酯聚合物、烯丙基胺-順丁烯二酸共聚物、甲基丙烯酸胺基乙酯-甲基丙烯酸共聚物、乙烯基吡啶-順丁烯二酸共聚物、甲基丙烯酸甲基胺基乙酯-丙烯酸共聚物、乙烯基吡啶-伊康酸共聚物、甲基烯丙基胺-伊康酸共聚物等。 兩性高分子就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸硬脂酯共聚物。 (高分子之分子量) 高分子之重量平均分子量就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為3,000以上，更佳為10,000以上，進而較佳為30,000以上，又，就C4二羧酸結晶懸浮液之過濾性、過濾後之濾餅之含水率之觀點而言，較佳為2,000,000以下，更佳為1,000,000以下，進而較佳為500,000以下。 高分子之重量平均分子量較佳為3,000以上且2,000,000以下，更佳為10,000以上且1,000,000以下，進而較佳為30,000以上且500,000以下。高分子之重量平均分子量例如可藉由凝膠滲透層析法(GPC)法而測定。 (高分子之含量) 析出C4二羧酸之結晶時之高分子之濃度就使高吸油量之C4二羧酸結晶化之觀點而言，於含有C4二羧酸或其鹽之水溶液中，較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，就工業生產性、成本之觀點而言，較佳為5質量%以下，更佳為1.5質量%以下，進而較佳為1質量%以下，進而較佳為0.5質量%以下。 含有C4二羧酸或其鹽之水溶液中之高分子之含量較佳為0.001質量%以上且5質量%以下，更佳為0.01質量%以上且1.5質量%以下，進而較佳為0.05質量%以上且1質量%以下，進而較佳為0.05質量%以上且0.5質量%以下。 又，含有C4二羧酸或其鹽之水溶液中之高分子之含量相對於C4二羧酸之含量(C4二羧酸之含量與將C4二羧酸鹽換算成C4二羧酸時之含量的和)的質量比就使高吸油量之二羧酸結晶化之觀點而言，較佳為0.001～0.5，更佳為0.002～0.3。 (非離子性界面活性劑及高分子之含量) 於本發明中，於將(a1)～(a2)之非離子性界面活性劑與(b1)～(b3)之高分子組合而使用之情形時，其合計含量於含有C4二羧酸或其鹽之水溶液中，較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，就發泡等工業操作性、成本之觀點而言，較佳為10質量%以下，更佳為3質量%以下，進而較佳為2質量%以下。 含有C4二羧酸或其鹽之水溶液中之(a1)～(a2)之非離子性界面活性劑及(b1)～(b3)之高分子的合計含量較佳為0.001質量%以上且10質量%以下，更佳為0.01質量%以上且3質量%以下，進而較佳為0.05質量%以上且2質量%以下。 (析出C4二羧酸結晶之方法) 析出C4二羧酸結晶之方法並無特別限定，可利用藉由調整pH值所進行之析出方法、藉由冷卻所進行之析出方法、藉由濃縮所進行之析出方法、藉由反應所進行之析出方法等操作而進行。 (晶析裝置) C4二羧酸結晶之析出較佳為使用具有攪拌翼之反應槽一邊攪拌一邊進行。攪拌翼為任何形狀均可，但為了特別良好地進行結晶之混合，較佳為槳翼、渦輪翼、螺旋槳翼、錨翼、大翼徑槳翼、攪拌槳翼。 攪拌之周速就使高吸油量之C4二羧酸均勻地晶析之觀點而言，較佳為0.2 m/s以上，更佳為0.3 m/s以上，進而較佳為0.5 m/s以上，又，就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為10 m/s以下，更佳為5 m/s以下，進而較佳為3 m/s以下。 攪拌之周速較佳為0.2 m/s以上且10 m/s以下，更佳為0.3 m/s以上且5 m/s以下，進而較佳為0.5 m/s以上且3 m/s以下。 (藉由調整pH值所進行之析出方法) 藉由調整pH值所進行之析出方法係藉由添加酸而使C4二羧酸自C4二羧酸鹽游離，將C4二羧酸之濃度提高至溶解度以上，而可晶析出C4二羧酸。 調整pH值時使用之酸只要為pKa小於C4二羧酸之酸，則可無特別限制地使用，尤其是較佳為無機酸。作為無機酸，例如可列舉：鹽酸、硝酸、硫酸、磷酸等。較佳為硫酸、鹽酸。 進行析出時之pH值就C4二羧酸之回收率之觀點而言，較佳為將開始晶析時之pH值調整至9以下，較佳為6以下，且較佳為藉由酸添加而調整至2.5以下。又，就反應槽等之腐蝕性之觀點而言，較佳為pH值0.5以上。 進行結晶析出時之pH值較佳為0.5以上且9以下，更佳為0.5以上且6以下，進而較佳為0.5以上且2.5以下。 酸之添加速度就使高吸油量之C4二羧酸結晶化之觀點而言，較佳為0.1 mmol-酸/L/min以上，更佳為0.3 mmol-酸/L/min以上，進而較佳為1 mmol-酸/L/min以上，又，就C4二羧酸結晶懸浮液之過濾性、過濾後之C4二羧酸濾餅之含水率之觀點而言，較佳為10 mmol-酸/L/min以下，更佳為5 mmol-酸/L/min以下，進而較佳為3 mmol-酸/L/min以下，進而較佳為2 mmol-酸/L/min以下。 酸之添加速度較佳為0.1 mmol-酸/L/min以上且10 mmol-酸/L/min以下，更佳為0.3 mmol-酸/L/min以上且5 mmol-酸/L/min以下，進而較佳為0.3 mmol-酸/L/min以上且3 mmol-酸/L/min以下，進而較佳為1 mmol-酸/L/min以上且2 mmol-酸/L/min以下。 再者，所謂mmol-酸/L/min係表示每分鐘向每升反應液中混合之酸量。 進行藉由調整pH值所進行之析出時之溫度並無特別限定，就C4二羧酸之回收率之觀點而言，較佳為以較低之溫度實施。晶析溫度就C4二羧酸之回收率之觀點而言，較佳為50℃以下，更佳為40℃以下，進而較佳為30℃以下，又，較佳為0℃以上，更佳為5℃以上。 晶析溫度較佳為0℃以上且50℃以下，更佳為0℃以上且40℃以下，進而較佳為5℃以上且30℃以下。 進行藉由調整pH值所進行之析出時之C4二羧酸或其鹽之濃度並無特別限定，就C4二羧酸之回收率之觀點而言，較佳為於析出開始時之溫度下之溶解度量、或略少於其之量。具體而言，含有C4二羧酸或其鹽之水溶液中之C4二羧酸或其鹽之濃度較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下、又，較佳為1質量%以上，更佳為2質量%以上。 進行藉由調整pH值所進行之析出時之含有C4二羧酸或其鹽的水溶液中之C4二羧酸或其鹽之含量較佳為1質量%以上且45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 (藉由冷卻所進行之析出方法) 藉由冷卻所進行之析出方法係藉由將含有C4二羧酸或其鹽之水溶液自高溫冷卻至低溫，而將C4二羧酸濃度提高至溶解度以上，從而能夠晶析出C4二羧酸。 C4二羧酸具有於溫度較高之情形時溶解度較高之性質，因此較佳為進行升溫而提高所溶解之酸濃度後，再進行冷卻。 升溫溫度較佳為60℃以上，更佳為70℃以上，進而較佳為80℃以上，又，較佳為120℃以下。 升溫溫度較佳為60℃以上且120℃以下，更佳為70℃以上且120℃以下，進而較佳為80℃以上且120℃以下。 冷卻溫度就C4二羧酸回收率之觀點而言，較佳為50℃以下，更佳為40℃以下，進而較佳為30℃以下，又，較佳為0℃以上，更佳為5℃以上。 冷卻溫度較佳為0℃以上且50℃以下，更佳為0℃以上且40℃以下，進而較佳為5℃以上且30℃以下。 根據自升溫溫度至冷卻溫度為止所需之時間而算出之平均冷卻速度就C4二羧酸之回收率之觀點、及使高吸油量之C4二羧酸結晶化之觀點而言，較佳為0.05℃/min以上，更佳為0.1℃/min以上，又，就結晶對反應槽之附著性、C4二羧酸結晶懸浮液之過濾性、過濾後之C4二羧酸濾餅之含水率之觀點而言，較佳為20℃/min以下，更佳為10℃/min以下，進而較佳為5℃/min以下。 根據自升溫溫度至冷卻溫度為止所需之時間而算出之平均冷卻速度較佳為0.05℃/min以上且20℃/min以下，更佳為0.1℃/min以上且10℃/min以下，進而較佳為0.1℃/min以上且5℃/min以下。 藉由冷卻所進行之析出方法中之pH值就C4二羧酸之回收率之觀點而言，較佳為將開始晶析時之pH值調整至4以下，更佳為調整至2.5以下。又，就反應槽等之腐蝕性之觀點而言，pH值較佳為0.5以上。 進行藉由冷卻所進行之析出時之C4二羧酸或其鹽之濃度並無特別限定，就C4二羧酸之回收率之觀點而言，較佳為於析出開始時之溫度下之溶解度量、或略少於其之量。具體而言，含有C4二羧酸或其鹽之水溶液中之C4二羧酸或其鹽之濃度較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下，又，較佳為1質量%以上，更佳為2質量%以上。 進行藉由冷卻所進行之析出時之含有C4二羧酸或其鹽之水溶液中之C4二羧酸或其鹽之含量較佳為1質量%以上且45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 (藉由濃縮所進行之析出方法) 藉由濃縮所進行之析出方法係藉由使含有C4二羧酸或其鹽之水溶液之溶劑(水)蒸發而進行濃縮，將C4二羧酸濃度提高至溶解度以上，從而能夠晶析出C4二羧酸。 蒸發時之溫度並無特別限定，較佳為100℃以下，更佳為80℃以下，又，較佳為5℃以上。 蒸發時之溫度較佳為5℃以上且100℃以下，更佳為5℃以上且80℃以下。再者，亦可於減壓下進行蒸發。 進行藉由濃縮所進行之析出時之C4二羧酸或其鹽之濃度並無特別限定，較佳為設定為與C4二羧酸之各溫度之溶解度相當之濃度、或略少於其之濃度。具體而言，就回收率之觀點而言，含有C4二羧酸或其鹽之水溶液中之C4二羧酸或其鹽之濃度較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下，又，較佳為1質量%以上，更佳為2質量%以上。 進行藉由濃縮所進行之析出時之含有C4二羧酸或其鹽之水溶液中之C4二羧酸或其鹽之含量較佳為1質量%以上且45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 又，藉由濃縮所進行之析出方法中之pH值就C4二羧酸之回收率之觀點而言，較佳為將開始晶析時之pH值調整至4以下，更佳為調整至2.5以下。又，就反應槽等之腐蝕性之觀點而言，pH值較佳為0.5以上。 (藉由反應所進行之析出方法) 藉由反應所進行之析出方法可根據C4二羧酸之種類而進行適當設定。例如，於析出反丁烯二酸之情形時，藉由向含有順丁烯二酸或順丁烯二酸酐之水溶液中添加觸媒以生成反丁烯二酸，而將反丁烯二酸濃度提高至溶解度以上，從而能夠晶析出反丁烯二酸。含有順丁烯二酸或順丁烯二酸酐之水溶液中之順丁烯二酸或順丁烯二酸酐之含量較佳為5質量%以上，更佳為10質量%以上，更佳為20質量%以上，又，較佳為70質量%以下，更佳為50質量%以下，更佳為40質量%以下，更佳為30質量%以下。 進行藉由反應所進行之析出時之含有順丁烯二酸或順丁烯二酸酐之水溶液中之順丁烯二酸或順丁烯二酸酐之含量較佳為5質量%以上且70質量%以下，更佳為10質量%以上且50質量%以下，進而較佳為10質量%以上且40質量%以下，進而較佳為20質量%以上且30質量%以下。 反應時之溫度並無特別限定，較佳為60℃～100℃。 作為觸媒，只要為使C4二羧酸之生成反應進行之觸媒，則可無特別限制地使用，例如可列舉：硫脲、溴酸鹽、過硼酸鹽等。又，反應時亦可添加硫酸或鹽酸等無機酸。 該等析出方法可單獨實施，亦可將複數種方法組合而實施。例如，於本發明中，作為C4二羧酸結晶析出方法，可考慮將含有C4二羧酸或其鹽之水溶液升溫至80℃以上，於確認溶解後，以0.05℃/min以上之平均冷卻速度進行藉由冷卻所進行之析出，於達到30℃後，添加無機酸而使pH值下降至2.5以下等。 (C4二羧酸結晶懸浮液之過濾) C4二羧酸之結晶可藉由離心分離、過濾、傾析法等固液分離操作而分取。結晶之分離操作等較佳為於上述溫度範圍內進行。視需要亦可將如此而獲得之C4二羧酸結晶洗淨。視需要進行洗浄後，進行乾燥，藉此可獲得C4二羧酸結晶。 (C4二羧酸結晶之乾燥) 乾燥可使用層板式乾燥機、錐形乾燥機、槳式乾燥機、圓錐螺旋混合機、流動層乾燥機、真空攪拌乾燥機、盤式乾燥機等通常之乾燥機。為了維持吸油量較高之C4二羧酸結晶結構，較佳為不施加高剪切之乾燥方法。 乾燥溫度較佳為70℃以上，更佳為80℃以上，進而較佳為100℃以上，又，較佳為300℃以下，更佳為250℃以下，進而較佳為200℃以下，進而較佳為150℃以下，進而較佳為130℃以下，進而較佳為120℃以下。再者，亦可進行減壓乾燥。 乾燥後之C4二羧酸結晶視需要亦可進行過篩等處理。 藉由本發明之方法所獲得之C4二羧酸結晶於吸油量方面較高。因此，根據本發明之方法，能夠提高C4二羧酸結晶之吸油量。C4二羧酸結晶之較佳之吸油量如上所述。 高吸油性之C4二羧酸結晶並無特別限定，可用作樹脂原料或食品添加物等，適宜用作要求更多地擔載尤其期待保濕效果之油劑的沐浴劑之原料。 關於上述實施形態，本發明進而揭示以下之碳數為4之二羧酸結晶、製造方法、或提高方法。 ＜1＞一種碳數為4之二羧酸結晶，其依據JIS K 5101-13-2(2004)所測得之吸油量為40 mL/100 g～200 mL/100 g。 ＜2＞如＜1＞所記載之碳數為4之二羧酸結晶，其吸油量較佳為50 mL/100 g～200 mL/100 g，更佳為60 mL/100 g～200 mL/100 g，進而較佳為70 mL/100 g～200 mL/100 g。 ＜3＞如＜1＞或＜2＞所記載之碳數為4之二羧酸結晶，其較佳為反丁烯二酸、琥珀酸、蘋果酸、酒石酸、順丁烯二酸、或草醯乙酸之結晶，更佳為反丁烯二酸或琥珀酸之結晶，進而較佳為反丁烯二酸之結晶。 ＜4＞一種碳數為4之二羧酸結晶之製造方法，其包括如下步驟：於選自(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑、及(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑中之至少1種非離子性界面活性劑之存在下，自含有碳數為4之二羧酸或其鹽之水溶液析出碳數為4之二羧酸之結晶。 ＜5＞一種提高碳數為4之二羧酸結晶之吸油量的方法，其包括如下步驟：於選自(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑、及(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑中之至少1種非離子性界面活性劑之存在下，自含有碳數為4之二羧酸或其鹽之水溶液析出碳數為4之二羧酸之結晶。 ＜6＞如＜4＞或＜5＞所記載之方法，其中碳數為4之二羧酸或其鹽較佳為藉由源自石化原料之化學合成而獲得者。 ＜7＞如＜4＞至＜6＞中任一項所記載之方法，其中(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑較佳為選自聚氧乙烯烷基醚、聚氧乙烯山梨糖醇酐脂肪酸酯、聚氧乙烯山梨糖醇脂肪酸酯、聚氧乙烯蓖麻油、及聚氧乙烯氫化蓖麻油中之至少1種，更佳為選自聚氧乙烯烷基醚、聚氧乙烯山梨糖醇酐脂肪酸酯、及聚氧乙烯山梨糖醇脂肪酸酯中之至少1種，進而較佳為選自聚氧乙烯烷基醚及聚氧乙烯山梨糖醇脂肪酸酯中之至少1種。 ＜8＞如＜4＞至＜7＞中任一項所記載之方法，其中聚氧乙烯鏈中之環氧乙烷加成莫耳數以平均值計較佳為2以上，更佳為3以上，進而較佳為4以上，又，較佳為60以下，更佳為50以下，進而較佳為40以下，進而更佳為30以下，進而更佳為25以下，進而更佳為20以下，又，較佳為2以上且60以下，更佳為3以上且50以下，進而較佳為3以上且40以下，進而較佳為3以上且30以下，進而較佳為4以上且25以下，進而較佳為4以上且20以下。 ＜9＞如＜4＞至＜8＞中任一項所記載之方法，其中非離子性界面活性劑之脂肪酸部分、烷基部分及烯基部分之碳數較佳為6以上，更佳為8以上，進而較佳為10以上，又，較佳為24以下，更佳為22以下，進而較佳為20以下，又，較佳為6以上且24以下，更佳為8以上且22以下，進而較佳為10以上且20以下。 ＜10＞如＜4＞至＜9＞中任一項所記載之方法，其中(a1)HLB為10以下之具有聚氧乙烯鏈之非離子性界面活性劑的HLB較佳為1以上，更佳為4以上，進而較佳為5以上，又，較佳為1以上且10以下，更佳為4以上且10以下，進而較佳為5以上且10以下。 ＜11＞如＜4＞至＜10＞中任一項所記載之方法，其中(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑較佳為選自山梨糖醇酐脂肪酸酯及烷基葡糖苷中之至少1種。 ＜12＞如＜4＞至＜11＞中任一項所記載之方法，其中(a2)HLB未達15之不具有聚氧乙烯鏈之非離子性界面活性劑的HLB較佳為4以上，更佳為8以上，進而較佳為10以上，又，較佳為13以下，又，較佳為4以上且未達15，更佳為8以上且13以下，進而較佳為10以上且13以下。 ＜13＞如＜4＞至＜12＞中任一項所記載之方法，其中含有碳數為4之二羧酸或其鹽的水溶液中之非離子性界面活性劑之含量較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，較佳為5質量%以下，更佳為1.5質量%以下，進而較佳為1質量%以下，又，較佳為0.001質量%以上且5質量%以下，更佳為0.01質量%以上且1.5質量%以下，進而較佳為0.05質量%以上且1質量%以下。 ＜14＞如＜4＞至＜13＞中任一項所記載之方法，其中含有碳數為4之二羧酸或其鹽的水溶液中之非離子性界面活性劑之含量相對於碳數為4之二羧酸之含量的比(質量比)較佳為0.001～0.5，更佳為0.002～0.3，進而較佳為0.01～0.3。 ＜15＞一種碳數為4之二羧酸結晶之製造方法，其包括如下步驟：於選自(b1)非離子性高分子、(b2)陽離子性高分子、及(b3)兩性高分子中之至少1種高分子之存在下，自含有碳數為4之二羧酸或其鹽之水溶液析出碳數為4之二羧酸之結晶。 ＜16＞一種提高碳數為4之二羧酸結晶之吸油量的方法，其包括如下步驟：於選自(b1)非離子性高分子、(b2)陽離子性高分子、及(b3)兩性高分子中之至少1種高分子之存在下，自含有碳數為4之二羧酸或其鹽之水溶液析出碳數為4之二羧酸之結晶。 ＜17＞如＜15＞或＜16＞所記載之方法，其中碳數為4之二羧酸或其鹽較佳為藉由源自石化原料之化學合成而獲得者。 ＜18＞如＜15＞至＜17＞中任一項所記載之方法，其中(b1)非離子性高分子較佳為選自澱粉系高分子、纖維素系高分子及乙烯基系高分子中之至少1種，更佳為使具有乙烯基之單體聚合之乙烯基系高分子、及/或纖維素系高分子，進而較佳為聚乙烯醇、及/或羥乙基纖維素。 ＜19＞如＜15＞至＜18＞中任一項所記載之方法，其中(b2)陽離子性高分子較佳為陽離子化纖維素。 ＜20＞如＜15＞至＜19＞中任一項所記載之方法，其中(b3)兩性高分子較佳為甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸硬脂酯共聚物。 ＜21＞如＜15＞至＜20＞中任一項所記載之方法，其中高分子之重量平均分子量較佳為3,000以上，更佳為10,000以上，進而較佳為30,000以上，又，較佳為2,000,000以下，更佳為1,000,000以下，進而較佳為500,000以下，又，較佳為3,000以上且2,000,000以下，更佳為10,000以上且1,000,000以下，進而較佳為30,000以上且500,000以下。 ＜22＞如＜15＞至＜21＞中任一項所記載之方法，其中含有碳數為4之二羧酸或其鹽之水溶液中之高分子之含量較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，較佳為5質量%以下，更佳為1.5質量%以下，進而較佳為1質量%以下，進而較佳為0.5質量%以下，又，較佳為0.001質量%以上且5質量%以下，更佳為0.01質量%以上且1.5質量%以下，進而較佳為0.05質量%以上且1質量%以下，進而較佳為0.05質量%以上且0.5質量%以下。 ＜23＞如＜15＞至＜22＞中任一項所記載之方法，其中含有碳數為4之二羧酸或其鹽的水溶液中之高分子之含量相對於碳數為4之二羧酸之含量的質量比較佳為0.001～0.5，更佳為0.002～0.3。 ＜24＞如＜4＞至＜23＞中任一項所記載之方法，其中含有碳數為4之二羧酸或其鹽之水溶液中之(a1)～(a2)之非離子性界面活性劑與(b1)～(b3)之高分子之合計含量較佳為0.001質量%以上，更佳為0.01質量%以上，進而較佳為0.05質量%以上，又，較佳為10質量%以下，更佳為3質量%以下，進而較佳為2質量%以下，又，較佳為0.001質量%以上且10質量%以下，更佳為0.01質量%以上且3質量%以下，進而較佳為0.05質量%以上且2質量%以下。 ＜25＞如＜4＞至＜24＞中任一項所記載之方法，其中析出結晶之方法係選自藉由調整pH值所進行之析出、藉由冷卻所進行之析出、藉由濃縮所進行之析出及藉由反應所進行之析出中之1種以上之方法。 ＜26＞如＜25＞所記載之方法，其中進行藉由調整pH值所進行之結晶析出時之pH值較佳為9以下，更佳為6以下，進而較佳為2.5以下，又，較佳為pH值為0.5以上，又，較佳為0.5以上且9以下，更佳為0.5以上且6以下，進而較佳為0.5以上且2.5以下。 ＜27＞如＜25＞或＜26＞所記載之方法，其中進行藉由調整pH值所進行之結晶析出時之酸之添加速度較佳為0.1 mmol-酸/L/min以上，更佳為0.3 mmol-酸/L/min以上，進而較佳為1 mmol-酸/L/min以上，又，較佳為10 mmol-酸/L/min以下，更佳為5 mmol-酸/L/min以下，進而較佳為3 mmol-酸/L/min以下，進而較佳為2 mmol-酸/L/min以下，又，較佳為0.1 mmol-酸/L/min以上且10 mmol-酸/L/min以下，更佳為0.3 mmol-酸/L/min以上且5 mmol-酸/L/min以下，進而較佳為0.3 mmol-酸/L/min以上且3 mmol-酸/L/min以下，進而較佳為1 mmol-酸/L/min以上且2 mmol-酸/L/min以下。 ＜28＞如＜27＞所記載之方法，其中酸較佳為無機酸，更佳為選自鹽酸、硝酸、硫酸、及磷酸中之1種以上，進而較佳為硫酸、或鹽酸。 ＜29＞如＜25＞至＜28＞中任一項所記載之方法，其中藉由調整pH值而進行結晶析出時之溫度較佳為50℃以下，更佳為40℃以下，進而較佳為30℃以下，又，較佳為0℃以上，更佳為5℃以上，又，較佳為0℃以上且50℃以下，更佳為0℃以上且40℃以下，進而較佳為5℃以上且30℃以下。 ＜30＞如＜25＞至＜29＞中任一項所記載之方法，其中進行藉由調整pH值所進行之結晶析出時之含有碳數為4之二羧酸或其鹽之水溶液中之碳數為4之二羧酸或其鹽之含量較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下，又，較佳為1質量%以上，更佳為2質量%以上，又，較佳為1質量%以上且45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 ＜31＞如＜25＞所記載之方法，其中藉由冷卻所進行之結晶析出較佳為將含有碳數為4之二羧酸或其鹽之水溶液升溫後進行。 ＜32＞如＜31＞所記載之方法，其中升溫溫度較佳為60℃以上，更佳為70℃以上，進而較佳為80℃以上，又，較佳為120℃以下，又，較佳為60℃以上且120℃以下，更佳為70℃以上且120℃以下，進而較佳為80℃以上且120℃以下。 ＜33＞如＜25＞、＜31＞或＜32＞所記載之方法，其中冷卻溫度較佳為50℃以下，更佳為40℃以下，進而較佳為30℃以下，又，較佳為0℃以上，更佳為5℃以上，又，較佳為0℃以上且50℃以下，更佳為0℃以上且40℃以下，進而較佳為5℃以上且30℃以下。 ＜34＞如＜31＞至＜33＞中任一項所記載之方法，其中根據自升溫溫度至冷卻溫度為止所需之時間而算出之平均冷卻速度較佳為0.05℃/min以上，更佳為0.1℃/min以上，又，較佳為20℃/min以下，更佳為10℃/min以下，進而較佳為5℃/min以下，又，較佳為0.05℃/min以上且20℃/min以下，更佳為0.1℃/min以上且10℃/min以下，進而較佳為0.1℃/min以上且5℃/min以下。 ＜35＞如＜25＞、＜31＞至＜34＞中任一項所記載之方法，其中進行藉由冷卻所進行之結晶析出時之pH值較佳為4以下，更佳為2.5以下，又，較佳為pH值為0.5以上，又，較佳為0.5以上且4以下，更佳為0.5以上且2.5以下。 ＜36＞如＜25＞、＜31＞至＜35＞中任一項所記載之方法，其中進行藉由冷卻所進行之結晶析出時之含有碳數為4之二羧酸或其鹽的水溶液中之碳數為4之二羧酸或其鹽之含量較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下，又，較佳為1質量%以上，更佳為2質量%以上，又，較佳為1質量%以上且45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 ＜37＞如＜25＞所記載之方法，其中藉由濃縮所進行之結晶析出係藉由使含有碳數為4之二羧酸或其鹽之水溶液之溶劑蒸發，繼而進行濃縮而進行，蒸發時之溫度較佳為100℃以下，更佳為80℃以下，又，較佳為5℃以上，又，較佳為5℃以上且100℃以下，更佳為5℃以上且80℃以下。 ＜38＞如＜25＞或＜37＞所記載之方法，其中進行藉由濃縮所進行之結晶析出時之含有碳數為4之二羧酸或其鹽的水溶液中之碳數為4之二羧酸或其鹽之含量較佳為45質量%以下，更佳為40質量%以下，進而較佳為20質量%以下，又，較佳為1質量%以上，更佳為2質量%以上，又，較佳為1質量%以上、45質量%以下，更佳為1質量%以上且40質量%以下，進而較佳為2質量%以上且20質量%以下。 ＜39＞如＜25＞、＜37＞或＜38＞所記載之方法，其中進行藉由濃縮所進行之結晶析出時之pH值較佳為4以下，更佳為2.5以下，又，較佳為pH值為0.5以上，又，較佳為0.5以上且4以下，更佳為0.5以上且2.5以下。 ＜40＞如＜4＞至＜39＞中任一項所記載之方法，其藉由如下方式進行結晶析出：將含有碳數為4之二羧酸或其鹽之水溶液升溫至80℃以上，於確認溶解後，以0.05℃/min以上之平均冷卻速度進行藉由冷卻所進行之析出，於達到30℃後，添加無機酸而使pH值下降至2.5以下。 ＜41＞如＜4＞至＜40＞中任一項所記載之方法，其中碳數為4之二羧酸結晶較佳為反丁烯二酸、琥珀酸、蘋果酸、酒石酸、順丁烯二酸、或草醯乙酸之結晶，更佳為反丁烯二酸或琥珀酸之結晶，進而較佳為反丁烯二酸結晶。 ＜42＞如＜25＞所記載之方法，其中碳數為4之二羧酸結晶為反丁烯二酸結晶，藉由向含有順丁烯二酸或順丁烯二酸酐之水溶液中添加觸媒進行生成反丁烯二酸之反應，而進行結晶析出。 ＜43＞如＜42＞所記載之方法，其中含有順丁烯二酸或順丁烯二酸酐之水溶液中之順丁烯二酸或順丁烯二酸酐之含量較佳為5質量%以上，更佳為10質量%以上，更佳為20質量%以上，又，較佳為70質量%以下，更佳為50質量%以下，更佳為40質量%以下，更佳為30質量%以下，又，較佳為5質量%以上且70質量%以下，更佳為10質量%以上且50質量%以下，進而較佳為10質量%以上且40質量%以下，進而較佳為20質量%以上且30質量%以下。 ＜44＞如＜42＞或＜43＞所記載之方法，其中觸媒較佳為硫脲、溴酸鹽、或過硼酸鹽。 ＜45＞如＜4＞至＜44＞中任一項所記載之方法，其一邊以較佳為周速0.2 m/s以上，更佳為周速0.3 m/s以上，進而較佳為周速0.5 m/s以上，又，較佳為周速10 m/s以下，更佳為周速5 m/s以下，進而較佳為周速3 m/s以下，又，較佳為周速0.2 m/s以上且10 m/s以下，更佳為周速0.3 m/s以上且5 m/s以下，進而較佳為周速0.5 m/s以上且3 m/s以下進行攪拌，一邊進行結晶析出。 ＜46＞如＜4＞至＜45＞中任一項所記載之方法，其中碳數為4之二羧酸結晶依據JIS K 5101-13-2(2004)所測得之吸油量較佳為40 mL/100 g～200 mL/100 g，更佳為50 mL/100 g～200 mL/100 g，進而較佳為60 mL/100 g～200 mL/100 g，進而較佳為70 mL/100 g～200 mL/100 g。 [實施例] [C4二羧酸] ・反丁烯二酸：日本觸媒(股份)製造 ・反丁烯二酸：川崎化成社工業(股份)製造 ・琥珀酸：和光純藥工業(股份)製造 ・DL-蘋果酸：和光純藥工業(股份)製造 ・順丁烯二酸：和光純藥工業(股份)製造 [界面活性劑] (非離子性界面活性劑) ・聚氧乙烯(2.5)月桂醚：Emulgen(註冊商標)102，HLB 6.8，花王(股份)製造 ・聚氧乙烯(4)月桂醚：Emulgen 104，HLB 8.6，花王(股份)製造 ・聚氧乙烯(6)硬脂醚：Emulgen 306P，HLB 8.3，花王(股份)製造 ・山梨糖醇酐單月桂酸酯：Emasol(註冊商標)L-10V，HLB 10.8，花王(股份)製造 ・山梨糖醇酐單硬脂酸酯：Emasol S-10V，HLB 8.1，花王(股份)製造 ・月桂基糖苷：MYDOL(註冊商標)12(有效成分40%)，HLB 12.5，花王(股份)製造 ・聚氧乙烯(40)山梨糖醇四油酸酯：RHEODOL 440V，HLB 9.9，花王(股份)製造 ・聚氧乙烯(30)山梨糖醇四油酸酯：RHEODOL 430V，HLB 8.6，花王(股份)製造 ・聚氧乙烯(20)山梨糖醇酐三油酸酯：RHEODOL TW-O320V，HLB 8.0，花王(股份)製造 ・聚氧乙烯(6)月桂醚：Emulgen 108，HLB 10.3，花王(股份)製造(比較例) ・聚氧乙烯(47)月桂醚：Emulgen 150，HLB 16.8，花王(股份)製造(比較例) ・聚氧乙烯(20)山梨糖醇酐單月桂酸酯：Emasol L-120V，HLB 14.9，花王(股份)製造(比較例) (陰離子界面活性劑) ・月桂基硫酸鈉(Emal(註冊商標)0，花王(股份)製造)(比較例) (陽離子界面活性劑) ・溴化鯨蠟基三甲基銨(和光純藥工業(股份)製造)(比較例) 上述所記載之HLB係根據上述所記載之小田、寺村等人之無機性值、有機性值所算出之數值。 [高分子] (非離子性高分子) ・聚乙烯吡咯啶酮K30(和光純藥工業(股份)製造) ・聚乙烯醇(重量平均分子量100,000，MP Biomedical公司製造) ・羥乙基纖維素(200～300 mPa・s、20℃下之2%水溶液，東京化成工業股份有限公司製造) (陽離子性高分子) ・羥乙基纖維素氯化羥丙基三甲基銨醚：Poiz(註冊商標)C-60H，花王(股份)製造 (兩性高分子) ・甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸硬脂酯共聚物：Lipidure(註冊商標)NR(高分子濃度5%)，日油(股份)製造 (陰離子性高分子) ・聚丙烯酸(重量平均分子量250000)(和光純藥工業(股份)製造)(比較例) [吸油量之測定] 關於吸油量，依據JIS K 5101-13-2，取1～5 g之試樣置於測定板(尺寸大於300×400 mm之平滑玻璃板)上之中央部，將煮亞麻籽油自滴定管以每次4、5滴緩慢地滴下至試樣之中央，每一次均使用平刮刀使整體充分地混練。反覆進行煮亞麻籽油之滴下及混練，直至整體變為硬膩子狀之塊之後，逐滴地進行混練，並將成為滴下最後1滴後能夠使用平刮刀將其捲成螺旋形之狀態時設為終點。其中，於無法捲成螺旋狀之情形時，將由於煮亞麻籽油之1滴而即將急遽變軟之前設為終點。以到達終點為止之操作時間成為7～15分鐘之間之方式對操作加以調節。 讀取到達終點時之滴定管內之煮亞麻籽油之滴下量，設為吸油量(單位：試樣每100 g之mL)。 [比較例1] 對川崎化成工業(股份)製造之反丁烯二酸之吸油量進行測定，結果為29.5 mL/100 g。 [比較例2] 對日本觸媒(股份)製造之反丁烯二酸之吸油量進行測定，結果為29.4 mL/100 g。 [比較例3] 對和光純藥工業(股份)製造之琥珀酸之吸油量進行測定，結果為27.3 mL/100 g。 [比較例4] 對和光純藥工業(股份)製造之DL-蘋果酸之吸油量進行測定，結果為28.0 mL/100 g。 [比較例5] 對和光純藥工業(股份)製造之順丁烯二酸之吸油量進行測定，結果為25.2 mL/100 g。 [比較例6] 藉由使用高速混合機PICCOLO SMP2(川田公司(股份)製造)，以翼徑140 mm、3000 r/min之速度攪拌20 min，而將日本觸媒(股份)製造之反丁烯二酸粉碎。對經粉碎之反丁烯二酸之吸油量進行測定，結果為36.6 mL/100 g。 將比較例1～6之結果示於表1。 [表1]
(藉由冷卻所進行之析出) [實施例1] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸(日本觸媒(股份)製造，以下至比較例13為止相同)817 g、聚氧乙烯(2.5)月桂醚(Emulgen 102)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.79℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙(ADVANTEC公司製造，以下相同)對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT(東京硝子器械(股份)製造，以下相同)，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為61.9 mL/100 g。 [實施例2] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚氧乙烯(4)月桂醚(Emulgen 104)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.63℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與實施例1同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為69.4 mL/100 g。 [實施例3] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚氧乙烯(40)山梨糖醇四油酸酯(RHEODOL 440V)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.86℃/min自85℃冷卻至24℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與實施例1同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為50.1 mL/100 g。 [實施例4] 於3 L之反應槽(直徑130 mm)中將離子交換水2.14 kg、反丁烯二酸105 g加以混合後，升溫至85℃而進行溶解。繼而，將2.25 g之聚氧乙烯(6)硬脂醚(Emulgen 306P)加以混合後，以平均冷卻速度0.45℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於250 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加500 g之離子交換水進行過濾洗浄。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT(東京硝子器械公司製造)，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為75.1 mL/100 g。 [實施例5] 於3 L之反應槽(直徑130 mm)中將離子交換水2.14 kg、反丁烯二酸105 g加以混合後，升溫至85℃而進行溶解。繼而，將2.25 g之聚氧乙烯(6)硬脂醚(Emulgen 306P)加以混合後，以平均冷卻速度0.094℃/min自85℃冷卻至26℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於250 r/min之條件下進行。晶析後之操作係實施與實施例4同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為85.6 mL/100 g。 [實施例6] 於3 L之反應槽(直徑130 mm)中將離子交換水2.57 kg、反丁烯二酸105 g、47%之硫酸(和光純藥工業(股份)製造)50 g、聚氧乙烯(20)山梨糖醇酐三油酸酯(RHEODOL TW-O320V)27.5 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.64℃/min自80℃冷卻至28℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於100 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加500 g之離子交換水進行過濾洗浄。濾液之pH值為0.99。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為75.8 mL/100 g。 [實施例7] 於3 L之反應槽(直徑130 mm)中將離子交換水2.52 kg、反丁烯二酸158 g、反丁烯二酸鈉(東京化成工業(股份)製造)72.5 g、聚氧乙烯(30)山梨糖醇四油酸酯(RHEODOL 430V)2.75 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.39℃/min自80℃冷卻至27℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加500 g之離子交換水進行過濾洗浄。濾液之pH值為3.6。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為59.2 mL/100 g。 [實施例8] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、山梨糖醇酐單月桂酸酯(Emasol L-10V)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度1.06℃/min自85℃冷卻至22℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與實施例1同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為79.5 mL/100 g。 [實施例9] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、山梨糖醇酐單硬脂酸酯(Emasol S-10V)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.89℃/min自85℃冷卻至24℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與實施例1同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為49.6 mL/100 g。 [實施例10] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、山梨糖醇酐單月桂酸酯(Emasol L-10V)1.75 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.70℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.0。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為51.7 mL/100 g。 [實施例11] 於100 L之反應槽(直徑450 mm)中將離子交換水80.0 kg、反丁烯二酸6.31 kg、月桂基葡糖苷(MYDOL 12)86.4 g加以混合後，升溫至92℃而進行溶解。繼而，以平均冷卻速度0.34℃/min自92℃冷卻至21℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加24.6 kg之離子交換水進行過濾洗浄。濾液之pH值為2.3。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為51.5 mL/100 g。 [實施例12] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚乙烯吡咯啶酮(聚乙烯吡咯啶酮K30)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度1.0℃/min自85℃冷卻至22℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.3。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為54.9 mL/100 g。 [實施例13] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚乙烯吡咯啶酮(聚乙烯吡咯啶酮K30)175 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.72℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為40.3 mL/100 g。 [實施例14] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚乙烯醇(分子量100000)1.75 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.68℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.1。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為62.9 mL/100 g。 [實施例15] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚乙烯醇(分子量100000)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.39℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為158.6 mL/100 g。 [實施例16] 於3 L之反應槽(直徑130 mm)中將離子交換水2.64 kg、反丁烯二酸105 g、羥乙基纖維素氯化羥丙基三甲基銨醚(Poiz C-60H)2.75 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.55℃/min自80℃冷卻至28℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為50.1 mL/100 g。 [實施例17] 於3 L之反應槽(直徑360 mm)中將離子交換水2.59 kg、反丁烯二酸105 g、甲基丙烯醯氧基乙基磷酸膽鹼-甲基丙烯酸硬脂酯共聚物(Lipidure NR)55 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.68℃/min自80℃冷卻至30℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為51.9 mL/100 g。 將實施例1～17之條件及結果示於表2及表3。 [實施例18] 於3 L之反應槽(直徑360 mm)中將離子交換水2.59 kg、反丁烯二酸105 g、羥乙基纖維素(羥乙基纖維素200-300mPa・s)1.13 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.60℃/min自80℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於250 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為115.0 mL/100 g。 [表2]
[表3]
[比較例7] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g加以混合後，升溫至85℃而使反丁烯二酸溶解。繼而，以平均冷卻速度0.98℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.3。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為25.4 mL/100 g。 [比較例8] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚氧乙烯(47)月桂醚(Emulgen 150)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.56℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.2。使用熱風循環乾燥器FS-60WT(東京硝子器械公司製造)，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為24.4 mL/100 g。 [比較例9] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚氧乙烯(6)月桂醚(Emulgen 108)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.63℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與比較例8同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為38.7 mL/100 g。 [比較例10] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、聚氧乙烯(20)山梨糖醇酐單月桂酸酯(Emasol L-120V)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.87℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與比較例8同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為33.7 mL/100 g。 [比較例11] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、月桂基硫酸鈉(Emal 0)17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.94℃/min自85℃冷卻至25℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與比較例8同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為22.8 mL/100 g。 [比較例12] 於35 L之反應槽(直徑360 mm)中將離子交換水16.7 kg、反丁烯二酸817 g、溴化鯨蠟基三甲基銨17.5 g加以混合後，升溫至85℃而進行溶解。繼而，以平均冷卻速度0.46℃/min自85℃冷卻至23℃，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。晶析後之操作係實施與比較例8同樣之操作。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為39.1 mL/100 g。 [比較例13] 於3 L之反應槽(直徑130 mm)中將離子交換水2.09 kg、反丁烯二酸105 g、聚丙烯酸(分子量250000)0.034 g加以混合後，升溫至80℃而進行溶解。繼而，以平均冷卻速度0.23℃/min自80℃冷卻至24℃，藉此使反丁烯二酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加500 g之離子交換水進行過濾洗浄。濾液之pH值為2.1。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為26.8 mL/100 g。 將比較例7～13之結果示於表4。 [表4]
如上述表1～表4所述，確認到藉由本發明之方法而晶析之反丁烯二酸結晶顯示出高吸油量。 (藉由調整pH值所進行之析出方法) [實施例19] 於80 L之反應槽中將離子交換水33.7 kg、反丁烯二酸(川崎化成工業(股份)製造)1.87 kg、48%之氫氧化鈉1.89 kg、聚氧乙烯(40)山梨糖醇四油酸酯(RHEODOL 440V)37.5 g加以混合，而溶解反丁烯二酸。該溶液之pH值為4.0。繼而，以平均酸添加速度1.82 mmol-H2
SO4
/L/min添加47%之硫酸(和光純藥工業(股份)製造)直至pH值成為2.1為止，藉此使反丁烯二酸析出。攪拌係使用翼徑150 mm之攪拌翼，於300 r/min之條件下進行。 其次，使用No.2之濾紙對析出之反丁烯二酸懸浮液進行抽氣過濾後，添加5.0 kg之離子交換水進行過濾洗浄。濾液之pH值為2.1。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之反丁烯二酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得反丁烯二酸結晶。 對所獲得之反丁烯二酸結晶之吸油量進行測定，結果為72.5 mL/100 g。 將實施例19之結果示於表5。 [表5]
如上述表5所示，確認到即便藉由調整pH值進行晶析，亦能夠獲得高吸油量之反丁烯二酸結晶。 (藉由冷卻所進行之析出方法) [實施例20] 於3 L之反應槽中將離子交換水1.81 kg、琥珀酸(和光純藥工業(股份)製造，以下相同)450 g加以混合後，升溫至80℃。繼而，將9.64 g之聚氧乙烯(6)硬脂醚(Emulgen 306P)加以混合後，以平均冷卻速度0.27℃/min自80℃冷卻至26℃，藉此使琥珀酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之琥珀酸懸浮液進行抽氣過濾。濾液之pH值為2.1。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之琥珀酸濾餅進行乾燥。乾燥後，藉由通過網眼710 μm之篩，而獲得琥珀酸結晶。 對所獲得之琥珀酸結晶之吸油量進行測定，結果為58.6 mL/100 g。 [實施例21] 於3 L之反應槽中將離子交換水1.80 kg、琥珀酸450 g加以混合後，升溫至80℃。繼而，將2.25 g之聚乙烯醇(分子量100000)加以混合後，以平均冷卻速度0.42℃/min自80℃冷卻至26℃，藉此使琥珀酸析出。攪拌係使用翼徑121 mm之攪拌翼，於150 r/min之條件下進行。 其次，使用No.2之濾紙對析出之琥珀酸懸浮液進行抽氣過濾。濾液之pH值為2.0。使用熱風循環乾燥器FS-60WT，於105℃下對過濾後之琥珀酸濾餅進行乾燥。乾燥後，藉由通過網眼500 μm之篩，而獲得琥珀酸結晶。 對所獲得之琥珀酸結晶之吸油量進行測定，結果為115.7 mL/100 g。 將實施例20及21之結果示於表6。 [表6]
如上述表6所述，確認到藉由本發明之方法而晶析之琥珀酸結晶顯示出高吸油量。However, the inventor actually pulverized commercially available fumaric acid as in Patent Document 3 and measured its oil absorption in accordance with JIS K 5101-13-2 (2004). The result was 36.6 mL/100 g (see below The comparative example 6). The oil absorption of commercially available C4 dicarboxylic acid is about 25-30 mL/100 g (refer to Comparative Examples 1 to 5 below). Although the oil absorption of crushed C4 dicarboxylic acid exceeds this amount, it is not sufficiently obtained due to pulverization.的油量。 The oil absorption. Therefore, the present invention is about providing a C4 dicarboxylic acid crystal with higher oil absorption and a method for producing the same. The present inventors found that in the presence of one or more selected from a specific nonionic surfactant, nonionic polymer, cationic polymer and amphoteric polymer in surfactants and polymers, The C4 dicarboxylic acid crystals obtained by crystallization of the aqueous solution containing C4 dicarboxylic acid or its salt have unprecedented high oil absorption. The C4 dicarboxylic acid crystal of the present invention has high oil absorption. Therefore, the C4 dicarboxylic acid crystal of the present invention can support more oil agents, and can be suitably used as a raw material for bathing agents and the like. In addition, according to the method of the present invention, the oil absorption of C4 dicarboxylic acid crystals can be increased, and C4 dicarboxylic acid crystals with high oil absorption can be obtained. [C4 dicarboxylic acid crystal] Regarding the C4 dicarboxylic acid crystal of the present invention, the oil absorption measured in accordance with JIS K 5101-13-2 (2004) is 40 mL/100 g to 200 mL/100 g. Examples of the C4 dicarboxylic acid in the present invention include fumaric acid, succinic acid, malic acid, tartaric acid, maleic acid, oxalic acid, and the like. Preferably it is fumaric acid or succinic acid, and more preferably is fumaric acid. Moreover, it is preferable that the dicarboxylic acid or its salt with a carbon number of 4 does not have an amino acid residue. JIS K 5101-13-2 (2004) is a method for measuring oil absorption by the boiled linseed oil method. The details of the measurement method are described in the examples. In this manual, "oil absorption measured in accordance with JIS K 5101-13-2 (2004)" is also referred to as "oil absorption". The oil absorption of the C4 dicarboxylic acid crystal of the present invention is 40 mL/100 g～200 mL/100 g, preferably 50 mL/100 g～200 mL/100 g, more preferably 60 mL/100 g～200 mL /100 g, more preferably 70 mL/100 g to 200 mL/100 g. [Method for producing C4 dicarboxylic acid crystals] The C4 dicarboxylic acid crystals of the present invention can also be produced by a method including the following steps: selected from (a1) non-ionic having a polyoxyethylene chain with HLB of 10 or less Surfactant, and (a2) at least one nonionic surfactant of nonionic surfactants with no polyoxyethylene chain with an HLB of less than 15 in the presence of a C4 dicarboxylic acid or its salt The aqueous solution precipitates the crystals of C4 dicarboxylic acid. In addition, C4 dicarboxylic acid crystals can also be produced by a method including the following steps: at least 1 selected from (b1) nonionic polymer, (b2) cationic polymer, and (b3) amphoteric polymer In the presence of this kind of polymer, crystals of C4 dicarboxylic acid are precipitated from the aqueous solution containing C4 dicarboxylic acid or its salt. In the present invention, the nonionic surfactants of (a1) to (a2) may be used alone, or they may be used in combination. In addition, the polymers of (b1) to (b3) may be used singly, or a plurality of them may be used in combination. When a plurality of them are combined, the nonionic surfactants of (a1) to (a2) and the polymers of (b1) to (b3) can also be used in combination. The nonionic surfactant and the polymer should just be present when the C4 dicarboxylic acid crystallizes, and the timing of adding these to the aqueous solution containing the C4 dicarboxylic acid or its salt is not particularly limited. (Aqueous solution containing C4 dicarboxylic acid or its salt) C4 dicarboxylic acid (fumaric acid, succinic acid, malic acid, tartaric acid, maleic acid, oxalic acid, etc.) or its salt is not particularly limited, It can be obtained by chemical synthesis from petrochemical raw materials such as benzene or butane, or by fermentation of microorganisms. Examples of chemical synthesis derived from petrochemical raw materials include: the isomerization reaction of maleic anhydride or maleic acid (fumaric acid) obtained by gas phase catalytic oxidation of petrochemical raw materials, etc. , Reduction reaction, hydrogenation reaction (succinic acid), hydration reaction (malic acid), hydration reaction of epoxytartaric acid (tartaric acid) obtained by the epoxidation reaction of maleic anhydride or maleic acid, etc. Examples of microorganisms that produce C4 dicarboxylic acid or its salt include filamentous fungi such as Rhizopus. In the case of obtaining C4 dicarboxylic acid or its salt by microbial fermentation, the crystal of C4 dicarboxylic acid can also be precipitated from the culture broth containing C4 dicarboxylic acid or its salt. (HLB of Nonionic Surfactant) In the present invention, HLB is an indicator of the Hydrophile-Lipophile Balance (Hydrophile-Lipophile Balance), based on the inorganic and organic values of Oda, Teramura, etc. The calculated value. The HLB calculated from the inorganic value and the organic value is specifically calculated by HLB=(Σinorganic value/Σorganic)×10. Here, for each of the "inorganic value" and "organic value", for example, for 1 carbon atom in the molecule, the "organic value" is 20, and for 1 hydroxyl group in the molecule, the "inorganic value" It is 100, so set the "inorganic value" and "organic value" corresponding to various atoms or functional groups (for example, refer to "Organic Concept Map-Basics and Applications -" by Yoshio Koda, page 11-17, Sankyo Publishing 1984 Issued annually), and accumulate the "inorganic value" and "organic value" of all the atoms and functional groups in the organic compound to calculate the HLB of the organic compound. Generally speaking, the HLB of a nonionic surfactant is a value of 1-20. In addition, when two or more types of nonionic surfactants are included, the HLB is calculated by adding up the HLB of each nonionic surfactant based on the blended mass ratio and averaging as shown in the following formula. Mixed HLB=Σ(HLB X ×W X )/ΣW X (where HLB X represents the HLB of the nonionic surfactant X, and W X represents the mass of the nonionic surfactant X with the value of HLB X ( g)). (Nonionic surfactant) The nonionic surfactant used in the present invention is selected from (a1) nonionic surfactants having polyoxyethylene chains with HLB of 10 or less, and (a2) HLB nonionic surfactants. At least one of 15 nonionic surfactants without polyoxyethylene chain. (A1) Nonionic surfactants having a polyoxyethylene chain with an HLB of 10 or less include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyethylene Oxyethylene polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkenyl ether, polyoxyethylene fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan Alcohol fatty acid ester, polyoxyethylene castor oil, polyoxyethylene hydrogenated castor oil, etc. Among them, from the viewpoint of crystallizing C4 dicarboxylic acids with high oil absorption, they are preferably selected from polyoxyethylene alkyl ethers, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene sorbitol fats. At least one of polyoxyethylene castor oil, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil, more preferably selected from polyoxyethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene sorbitan At least one kind of sugar alcohol fatty acid ester, more preferably at least one kind selected from polyoxyethylene alkyl ether and polyoxyethylene sorbitol fatty acid ester. In addition, the number of ethylene oxide addition moles in the polyoxyethylene chain is shown as an average value, and is preferably 2 or more, more preferably 3 or more, still more preferably 4 or more, and more preferably 60 or less, more It is preferably 50 or less, more preferably 40 or less, still more preferably 30 or less, still more preferably 25 or less, and still more preferably 20 or less. In addition, the carbon number of the fatty acid part, the alkyl part and the alkenyl part of the nonionic surfactant is preferably 6 or more, more preferably 8 or more, still more preferably 10 or more, and more preferably 24 or less, and more It is preferably 22 or less, and more preferably 20 or less. Furthermore, the so-called "having a polyoxyethylene chain" refers to a structure in which more than 1 mol of ethylene oxide is added to the molecule of the nonionic surfactant. (a1) The HLB of a nonionic surfactant having a polyoxyethylene chain with an HLB of 10 or less is preferably 1 or more, more preferably 4 or more from the standpoint of producing high oil absorption C4 dicarboxylic acid crystals , And more preferably 5 or more. (A2) Types of nonionic surfactants having no polyoxyethylene chain with an HLB of less than 15 include: polyglycerin fatty acid esters, glycerin fatty acid esters, ethylene glycol fatty acid esters, and propylene glycol fatty acid esters , Butanediol fatty acid ester, sorbitan fatty acid ester, sucrose fatty acid ester, alkyl glucoside, etc. Among them, from the viewpoint of producing high oil absorption C4 dicarboxylic acid crystals, at least one selected from the group consisting of sorbitan fatty acid esters and alkyl glucosides is preferred. (a2) The HLB of a nonionic surfactant without a polyoxyethylene chain with an HLB of less than 15 From the viewpoint of crystallizing a high oil absorption C4 dicarboxylic acid, it is preferably 4 or more, more preferably 8 Above, more preferably 10 or more, and more preferably 13 or less. (a2) The HLB of the nonionic surfactant with no polyoxyethylene chain having an HLB of less than 15 is preferably 4 or more and less than 15, more preferably 8 or more and 13 or less, and still more preferably 10 or more and 13 the following. Commercially available nonionic surfactants can be used. (Content of Nonionic Surfactant) The concentration of nonionic surfactant when crystals of C4 dicarboxylic acid are precipitated. From the viewpoint of crystallization of C4 dicarboxylic acid with high oil absorption, when C4 dicarboxylic acid is contained In the aqueous solution of the acid or its salt, it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.05% by mass or more. In addition, from the viewpoint of industrial operability such as foaming and cost, it is more It is preferably 5% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1% by mass or less. The content of the nonionic surfactant in the aqueous solution containing C4 dicarboxylic acid or its salt is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and more preferably 0.05% by mass or more and 1% by mass or less. In addition, in the present invention, the content of the nonionic surfactant in the aqueous solution containing C4 dicarboxylic acid or its salt is relative to the content of C4 dicarboxylic acid (the content of C4 dicarboxylic acid and the content of C4 dicarboxylic acid The ratio (mass ratio) of the sum of the content of C4 dicarboxylic acid) (mass ratio), from the viewpoint of producing high oil absorption C4 dicarboxylic acid crystals, is preferably 0.001 to 0.5, more preferably 0.002 to 0.3, and still more preferably 0.01 ~ 0.3. (Polymer) The polymer used in the present invention is at least one selected from (b1) nonionic polymers, (b2) cationic polymers, and (b3) amphoteric polymers. These polymers are preferably water-soluble. (B1) The nonionic polymer may be any one of a water-soluble synthetic polymer, a water-soluble semi-synthetic polymer, and a water-soluble natural polymer. Examples of nonionic polymers include starch-based polymers (for example, carboxymethyl starch, soluble starch, methyl starch, etc.), cellulose-based polymers (for example, alkyl cellulose, ethyl cellulose, etc.). Cellulose, hydroxyalkyl cellulose such as hydroxyethyl cellulose, hydroxypropyl methylcellulose, etc.), vinyl polymers (for example, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl methyl ether, etc.), poly Alkylene glycol and so on. From the viewpoint of crystallization of high oil absorption C4 dicarboxylic acid, the nonionic polymer is preferably a vinyl polymer or hydroxyalkyl cellulose obtained by polymerizing a monomer having a vinyl group, and more preferably For polyvinyl alcohol or hydroxyethyl cellulose. (B2) Cationic polymers include: cationized cellulose, cationized starch, cationized guar gum, polyethyleneimine-based polymers, dicyandiamide-based polymers, diallylamine-based polymers Polymers, etc. The cationic polymer is preferably cationized cellulose from the viewpoint of crystallization of C4 dicarboxylic acid with high oil absorption. (B3) Amphoteric polymers include: methacryloxyethylphosphocholine-methacrylic acid copolymer, methacryloxyethylphosphocholine-stearyl methacrylate copolymer, Ethyl betaine methacrylate-acrylic acid copolymer, styrene-acrylic acid-dialkylamino acrylate polymer, allylamine-maleic acid copolymer, aminoethyl methacrylate-methyl Acrylic copolymer, vinylpyridine-maleic acid copolymer, methylaminoethyl methacrylate-acrylic acid copolymer, vinylpyridine-itaconic acid copolymer, methallylamine-itaconic acid Copolymers and so on. From the viewpoint of crystallizing a high oil absorption C4 dicarboxylic acid, the amphoteric polymer is preferably a methacryloxyethylphosphocholine-stearyl methacrylate copolymer. (Molecular weight of polymer) The weight average molecular weight of the polymer is preferably 3,000 or more, more preferably 10,000 or more, and still more preferably 30,000 or more from the viewpoint of crystallization of high oil absorption C4 dicarboxylic acid. From the viewpoint of the filterability of the C4 dicarboxylic acid crystal suspension and the moisture content of the filter cake after filtration, it is preferably 2,000,000 or less, more preferably 1,000,000 or less, and still more preferably 500,000 or less. The weight average molecular weight of the polymer is preferably 3,000 or more and 2,000,000 or less, more preferably 10,000 or more and 1,000,000 or less, and still more preferably 30,000 or more and 500,000 or less. The weight average molecular weight of a polymer can be measured by, for example, a gel permeation chromatography (GPC) method. (Content of polymer) The concentration of polymer when the crystals of C4 dicarboxylic acid are precipitated. From the viewpoint of crystallization of C4 dicarboxylic acid with high oil absorption, it is better than that in an aqueous solution containing C4 dicarboxylic acid or its salt. It is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and from the viewpoint of industrial productivity and cost, it is preferably 5% by mass or less, and more preferably 1.5% by mass % Or less, more preferably 1% by mass or less, and still more preferably 0.5% by mass or less. The content of the polymer in the aqueous solution containing C4 dicarboxylic acid or its salt is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by mass or more and 1.5% by mass or less, and still more preferably 0.05% by mass or more And 1 mass% or less, More preferably, it is 0.05 mass% or more and 0.5 mass% or less. In addition, the content of the polymer in the aqueous solution containing C4 dicarboxylic acid or its salt relative to the content of C4 dicarboxylic acid The mass ratio of and) is preferably 0.001 to 0.5, more preferably 0.002 to 0.3 from the viewpoint of crystallizing a high oil absorption dicarboxylic acid. (Contents of nonionic surfactant and polymer) In the present invention, when the nonionic surfactant of (a1) to (a2) and the polymer of (b1) to (b3) are used in combination When the total content is in the aqueous solution containing C4 dicarboxylic acid or its salt, it is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, and still more preferably 0.05% by mass or more. In addition, for industrial foaming, etc. From the viewpoint of operability and cost, it is preferably 10% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. The total content of (a1)～(a2) nonionic surfactant and (b1)～(b3) polymer in the aqueous solution containing C4 dicarboxylic acid or its salt is preferably 0.001% by mass or more and 10% by mass % Or less, more preferably 0.01% by mass or more and 3% by mass or less, and still more preferably 0.05% by mass or more and 2% by mass or less. (Method of Precipitating Crystals of C4 Dicarboxylic Acid) The method of precipitating C4 dicarboxylic acid crystals is not particularly limited. The method of precipitation by adjusting the pH value, the precipitation method by cooling, and the method by concentration can be used. The precipitation method, the precipitation method performed by the reaction, and other operations are carried out. (Crystallizing device) The precipitation of C4 dicarboxylic acid crystals is preferably performed while stirring using a reaction tank with stirring blades. The stirring wing may have any shape, but in order to perform crystal mixing particularly well, it is preferably a blade, a turbine wing, a propeller wing, an anchor wing, a large-diameter blade, and a stirring blade. From the viewpoint of uniformly crystallization of high oil absorption C4 dicarboxylic acid, the peripheral speed of stirring is preferably 0.2 m/s or more, more preferably 0.3 m/s or more, and still more preferably 0.5 m/s or more In addition, from the viewpoint of crystallization of C4 dicarboxylic acid with high oil absorption, it is preferably 10 m/s or less, more preferably 5 m/s or less, and still more preferably 3 m/s or less. The peripheral speed of stirring is preferably 0.2 m/s or more and 10 m/s or less, more preferably 0.3 m/s or more and 5 m/s or less, and still more preferably 0.5 m/s or more and 3 m/s or less. (Precipitation method by adjusting the pH value) The precipitation method by adjusting the pH value is to free the C4 dicarboxylic acid from the C4 dicarboxylate by adding acid and increase the concentration of the C4 dicarboxylic acid to Above solubility, C4 dicarboxylic acid can be crystallized out. The acid used when adjusting the pH can be used without particular limitation as long as the pKa is less than that of the C4 dicarboxylic acid. In particular, an inorganic acid is preferred. As an inorganic acid, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, etc. are mentioned, for example. Preferred are sulfuric acid and hydrochloric acid. From the viewpoint of the recovery rate of C4 dicarboxylic acid during precipitation, it is preferable to adjust the pH value at the start of crystallization to 9 or less, preferably 6 or less, and it is more preferable to adjust the pH value by adding acid Adjust to less than 2.5. In addition, from the viewpoint of the corrosiveness of the reaction tank, etc., the pH is preferably 0.5 or more. The pH value at the time of crystallization is preferably 0.5 or more and 9 or less, more preferably 0.5 or more and 6 or less, and still more preferably 0.5 or more and 2.5 or less. From the viewpoint of crystallization of high oil absorption C4 dicarboxylic acid, the acid addition rate is preferably 0.1 mmol-acid/L/min or more, more preferably 0.3 mmol-acid/L/min or more, and more preferably 1 mmol-acid/L/min or more, and from the viewpoint of the filterability of the C4 dicarboxylic acid crystal suspension and the moisture content of the filtered C4 dicarboxylic acid cake, it is preferably 10 mmol-acid/ L/min or less, more preferably 5 mmol-acid/L/min or less, still more preferably 3 mmol-acid/L/min or less, and still more preferably 2 mmol-acid/L/min or less. The acid addition rate is preferably 0.1 mmol-acid/L/min or more and 10 mmol-acid/L/min or less, more preferably 0.3 mmol-acid/L/min or more and 5 mmol-acid/L/min or less, It is more preferably 0.3 mmol-acid/L/min or more and 3 mmol-acid/L/min or less, and still more preferably 1 mmol-acid/L/min or more and 2 mmol-acid/L/min or less. Furthermore, the so-called mmol-acid/L/min means the amount of acid mixed in each liter of the reaction solution per minute. The temperature at the time of performing precipitation by adjusting the pH value is not particularly limited, but from the viewpoint of the recovery rate of C4 dicarboxylic acid, it is preferable to perform it at a lower temperature. From the viewpoint of the recovery rate of C4 dicarboxylic acid, the crystallization temperature is preferably 50°C or less, more preferably 40°C or less, still more preferably 30°C or less, and more preferably 0°C or more, more preferably Above 5°C. The crystallization temperature is preferably 0°C or more and 50°C or less, more preferably 0°C or more and 40°C or less, and still more preferably 5°C or more and 30°C or less. The concentration of C4 dicarboxylic acid or its salt when performing precipitation by adjusting pH is not particularly limited. From the viewpoint of the recovery rate of C4 dicarboxylic acid, it is preferably at the temperature at the beginning of precipitation Dissolution measure, or slightly less than its amount. Specifically, the concentration of C4 dicarboxylic acid or its salt in the aqueous solution containing C4 dicarboxylic acid or its salt is preferably 45% by mass or less, more preferably 40% by mass or less, and still more preferably 20% by mass or less, Furthermore, it is preferably 1% by mass or more, and more preferably 2% by mass or more. The content of C4 dicarboxylic acid or its salt in the aqueous solution containing C4 dicarboxylic acid or its salt at the time of precipitation by adjusting the pH value is preferably 1% by mass or more and 45% by mass or less, more preferably 1 Mass% or more and 40% by mass or less, more preferably 2% by mass or more and 20% by mass or less. (Precipitation method by cooling) The precipitation method by cooling is to increase the concentration of C4 dicarboxylic acid above the solubility by cooling an aqueous solution containing C4 dicarboxylic acid or its salt from a high temperature to a low temperature. Thereby, C4 dicarboxylic acid can be crystallized out. C4 dicarboxylic acid has the property of higher solubility when the temperature is higher, so it is better to raise the temperature to increase the dissolved acid concentration and then cool it. The temperature rise temperature is preferably 60°C or higher, more preferably 70°C or higher, still more preferably 80°C or higher, and more preferably 120°C or lower. The temperature increase temperature is preferably 60°C or higher and 120°C or lower, more preferably 70°C or higher and 120°C or lower, and still more preferably 80°C or higher and 120°C or lower. From the viewpoint of the C4 dicarboxylic acid recovery rate, the cooling temperature is preferably 50°C or less, more preferably 40°C or less, still more preferably 30°C or less, and more preferably 0°C or more, more preferably 5°C above. The cooling temperature is preferably 0°C or higher and 50°C or lower, more preferably 0°C or higher and 40°C or lower, and still more preferably 5°C or higher and 30°C or lower. The average cooling rate calculated from the time required from the heating temperature to the cooling temperature is preferably 0.05 from the viewpoint of the recovery rate of C4 dicarboxylic acid and the viewpoint of crystallization of C4 dicarboxylic acid with high oil absorption ℃/min or more, more preferably 0.1℃/min or more, and in terms of the adhesion of crystals to the reaction tank, the filterability of the C4 dicarboxylic acid crystal suspension, and the moisture content of the filtered C4 dicarboxylic acid cake In particular, it is preferably 20°C/min or less, more preferably 10°C/min or less, and still more preferably 5°C/min or less. The average cooling rate calculated from the time required from the heating temperature to the cooling temperature is preferably 0.05°C/min or more and 20°C/min or less, more preferably 0.1°C/min or more and 10°C/min or less, and more Preferably, it is 0.1°C/min or more and 5°C/min or less. From the viewpoint of the recovery rate of C4 dicarboxylic acid, the pH value in the precipitation method performed by cooling is preferably adjusted to 4 or less at the start of crystallization, and more preferably adjusted to 2.5 or less. In addition, from the viewpoint of the corrosiveness of the reaction tank, etc., the pH value is preferably 0.5 or more. The concentration of C4 dicarboxylic acid or its salt during precipitation by cooling is not particularly limited. From the viewpoint of the recovery rate of C4 dicarboxylic acid, it is preferably a measure of dissolution at the temperature at the beginning of precipitation , Or slightly less than its amount. Specifically, the concentration of the C4 dicarboxylic acid or its salt in the aqueous solution containing the C4 dicarboxylic acid or its salt is preferably 45% by mass or less, more preferably 40% by mass or less, and still more preferably 20% by mass or less, Furthermore, it is preferably 1% by mass or more, and more preferably 2% by mass or more. The content of C4 dicarboxylic acid or its salt in the aqueous solution containing C4 dicarboxylic acid or its salt at the time of precipitation by cooling is preferably 1% by mass or more and 45% by mass or less, more preferably 1% by mass More than and 40% by mass or less, and more preferably 2% by mass or more and 20% by mass or less. (Precipitation method by concentration) The precipitation method by concentration is concentrated by evaporating the solvent (water) of an aqueous solution containing C4 dicarboxylic acid or its salt to increase the concentration of C4 dicarboxylic acid to Above the solubility, C4 dicarboxylic acid can be crystallized out. The temperature during evaporation is not particularly limited, but is preferably 100°C or lower, more preferably 80°C or lower, and more preferably 5°C or higher. The temperature during evaporation is preferably 5°C or higher and 100°C or lower, more preferably 5°C or higher and 80°C or lower. Furthermore, evaporation can also be carried out under reduced pressure. The concentration of C4 dicarboxylic acid or its salt during precipitation by concentration is not particularly limited, but it is preferably set to a concentration equivalent to or slightly less than the solubility of C4 dicarboxylic acid at each temperature . Specifically, from the viewpoint of recovery rate, the concentration of C4 dicarboxylic acid or its salt in the aqueous solution containing C4 dicarboxylic acid or its salt is preferably 45% by mass or less, more preferably 40% by mass or less, and further It is preferably 20% by mass or less, more preferably 1% by mass or more, and more preferably 2% by mass or more. The content of C4 dicarboxylic acid or its salt in the aqueous solution containing C4 dicarboxylic acid or its salt at the time of precipitation by concentration is preferably 1% by mass or more and 45% by mass or less, more preferably 1% by mass More than and 40% by mass or less, and more preferably 2% by mass or more and 20% by mass or less. Also, from the viewpoint of the recovery rate of C4 dicarboxylic acid in the pH value in the precipitation method by concentration, it is preferable to adjust the pH value at the start of crystallization to 4 or less, more preferably to 2.5 or less . In addition, from the viewpoint of the corrosiveness of the reaction tank, etc., the pH value is preferably 0.5 or more. (Precipitation method by reaction) The precipitation method by reaction can be appropriately set according to the kind of C4 dicarboxylic acid. For example, when fumaric acid is precipitated, by adding a catalyst to an aqueous solution containing maleic acid or maleic anhydride to generate fumaric acid, the concentration of fumaric acid is reduced When the solubility is increased to above, the fumaric acid can be crystallized out. The content of maleic acid or maleic anhydride in the aqueous solution containing maleic acid or maleic anhydride is preferably 5% by mass or more, more preferably 10% by mass or more, more preferably 20% by mass % Or more, more preferably 70% by mass or less, more preferably 50% by mass or less, more preferably 40% by mass or less, still more preferably 30% by mass or less. The content of maleic acid or maleic anhydride in the aqueous solution containing maleic acid or maleic anhydride at the time of precipitation by reaction is preferably 5% by mass or more and 70% by mass Hereinafter, it is more preferably 10% by mass or more and 50% by mass or less, still more preferably 10% by mass or more and 40% by mass or less, and still more preferably 20% by mass or more and 30% by mass or less. The temperature during the reaction is not particularly limited, but is preferably 60°C to 100°C. As the catalyst, as long as it is a catalyst that advances the formation reaction of C4 dicarboxylic acid, it can be used without particular limitation, and examples thereof include thiourea, bromate, perborate, and the like. In addition, mineral acids such as sulfuric acid or hydrochloric acid may be added during the reaction. These precipitation methods can be implemented individually or in combination of a plurality of methods. For example, in the present invention, as a method for crystallizing C4 dicarboxylic acid, it can be considered to raise the temperature of the aqueous solution containing C4 dicarboxylic acid or its salt to 80°C or more, and after confirming the dissolution, use an average cooling rate of 0.05°C/min or more The precipitation by cooling is performed, and after reaching 30°C, an inorganic acid is added to lower the pH to 2.5 or less. (Filtration of C4 Dicarboxylic Acid Crystal Suspension) Crystals of C4 dicarboxylic acid can be separated by solid-liquid separation operations such as centrifugal separation, filtration, and decantation. The separation operation of crystallization and the like are preferably carried out within the above-mentioned temperature range. If necessary, the C4 dicarboxylic acid crystals obtained in this way can also be washed. After washing as necessary, drying is performed to obtain C4 dicarboxylic acid crystals. (Drying of C4 dicarboxylic acid crystals) Drying can be carried out using ordinary drying such as layer dryers, cone dryers, paddle dryers, conical screw mixers, fluidized bed dryers, vacuum stirring dryers, disc dryers, etc. machine. In order to maintain the C4 dicarboxylic acid crystal structure with high oil absorption, a drying method without high shear is preferred. The drying temperature is preferably 70°C or higher, more preferably 80°C or higher, still more preferably 100°C or higher, more preferably 300°C or lower, more preferably 250°C or lower, still more preferably 200°C or lower, and furthermore It is preferably 150°C or lower, more preferably 130°C or lower, and still more preferably 120°C or lower. Furthermore, it can also be dried under reduced pressure. The dried C4 dicarboxylic acid crystals can be sieved and other treatments if necessary. The C4 dicarboxylic acid crystals obtained by the method of the present invention are relatively high in oil absorption. Therefore, according to the method of the present invention, the oil absorption of C4 dicarboxylic acid crystals can be increased. The preferred oil absorption of C4 dicarboxylic acid crystals is as described above. The C4 dicarboxylic acid crystals with high oil absorption are not particularly limited, and can be used as resin raw materials or food additives, etc., and are suitable for use as raw materials for bathing agents that require more oils that are especially expected to have moisturizing effects. Regarding the above-mentioned embodiment, the present invention further discloses the following dicarboxylic acid crystals with 4 carbon atoms, production methods, or improvement methods. <1> A dicarboxylic acid crystal with a carbon number of 4, which has an oil absorption measured in accordance with JIS K 5101-13-2 (2004) of 40 mL/100 g to 200 mL/100 g. <2> For the dicarboxylic acid crystals with 4 carbons as described in <1>, the oil absorption is preferably 50 mL/100 g～200 mL/100 g, more preferably 60 mL/100 g～200 mL/ 100 g, more preferably 70 mL/100 g to 200 mL/100 g. <3> The dicarboxylic acid crystals with 4 carbon atoms as described in <1> or <2>, which are preferably fumaric acid, succinic acid, malic acid, tartaric acid, maleic acid, or oxalic acid The crystal of acetic acid is more preferably the crystal of fumaric acid or succinic acid, and more preferably the crystal of fumaric acid. <4> A method for producing dicarboxylic acid crystals with a carbon number of 4, which comprises the following steps: selected from (a1) nonionic surfactants having polyoxyethylene chains with HLB of 10 or less, and (a2) In the presence of at least one of the nonionic surfactants with no polyoxyethylene chain without HLB of less than 15, carbon is precipitated from an aqueous solution containing a dicarboxylic acid or its salt with a carbon number of 4 The number is 4 crystals of dicarboxylic acid. <5> A method for increasing the oil absorption of dicarboxylic acid crystals with a carbon number of 4, which includes the following steps: selected from (a1) nonionic surfactants with polyoxyethylene chains with HLB of 10 or less, and (a2) In the presence of at least one nonionic surfactant among nonionic surfactants with no polyoxyethylene chain with an HLB of less than 15, from a dicarboxylic acid with a carbon number of 4 or its salt The aqueous solution precipitates crystals of a dicarboxylic acid with a carbon number of 4. <6> The method as described in <4> or <5>, wherein the dicarboxylic acid having a carbon number of 4 or its salt is preferably obtained by chemical synthesis derived from petrochemical raw materials. <7> The method as described in any one of <4> to <6>, wherein (a1) the nonionic surfactant having a polyoxyethylene chain with an HLB of 10 or less is preferably selected from polyoxyethylene At least one of polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene castor oil, and polyoxyethylene hydrogenated castor oil, more preferably selected from polyoxyethylene At least one of ethylene alkyl ether, polyoxyethylene sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester, and more preferably selected from polyoxyethylene alkyl ether and polyoxyethylene sorbitan At least one of alcohol and fatty acid esters. <8> The method as described in any one of <4> to <7>, wherein the number of ethylene oxide addition moles in the polyoxyethylene chain is preferably 2 or more, more preferably 3 or more on average , More preferably 4 or more, more preferably 60 or less, more preferably 50 or less, still more preferably 40 or less, still more preferably 30 or less, still more preferably 25 or less, and still more preferably 20 or less, Furthermore, it is preferably 2 or more and 60 or less, more preferably 3 or more and 50 or less, still more preferably 3 or more and 40 or less, still more preferably 3 or more and 30 or less, and still more preferably 4 or more and 25 or less, More preferably, it is 4 or more and 20 or less. <9> The method as described in any one of <4> to <8>, wherein the carbon number of the fatty acid part, the alkyl part and the alkenyl part of the nonionic surfactant is preferably 6 or more, more preferably 8 or more, more preferably 10 or more, more preferably 24 or less, more preferably 22 or less, still more preferably 20 or less, more preferably 6 or more and 24 or less, more preferably 8 or more and 22 or less , More preferably 10 or more and 20 or less. <10> The method as described in any one of <4> to <9>, wherein (a1) the HLB of the nonionic surfactant having a polyoxyethylene chain of 10 or less has an HLB of 1 or more, and more It is preferably 4 or more, more preferably 5 or more, more preferably 1 or more and 10 or less, more preferably 4 or more and 10 or less, and still more preferably 5 or more and 10 or less. <11> The method as described in any one of <4> to <10>, wherein (a2) the nonionic surfactant having an HLB of less than 15 and not having a polyoxyethylene chain is preferably selected from sorbitol At least one of anhydride fatty acid ester and alkyl glucoside. <12> The method as described in any one of <4> to <11>, wherein (a2) the HLB of the nonionic surfactant without a polyoxyethylene chain having an HLB of less than 15 is preferably 4 or more, More preferably 8 or more, still more preferably 10 or more, more preferably 13 or less, more preferably 4 or more and less than 15, more preferably 8 or more and 13 or less, and still more preferably 10 or more and 13 the following. <13> The method as described in any one of <4> to <12>, wherein the content of the nonionic surfactant in the aqueous solution containing a dicarboxylic acid with a carbon number of 4 or its salt is preferably 0.001 mass % Or more, more preferably 0.01 mass% or more, still more preferably 0.05 mass% or more, more preferably 5 mass% or less, more preferably 1.5 mass% or less, still more preferably 1 mass% or less, and more It is preferably 0.001 mass% or more and 5 mass% or less, more preferably 0.01 mass% or more and 1.5 mass% or less, and still more preferably 0.05 mass% or more and 1 mass% or less. <14> The method as described in any one of <4> to <13>, wherein the content of the nonionic surfactant in the aqueous solution containing the dicarboxylic acid with a carbon number of 4 or its salt is relative to the number of carbons The ratio (mass ratio) of the content of the dicarboxylic acid of 4 is preferably 0.001 to 0.5, more preferably 0.002 to 0.3, and still more preferably 0.01 to 0.3. <15> A method for producing dicarboxylic acid crystals with a carbon number of 4, comprising the following steps: selected from (b1) nonionic polymers, (b2) cationic polymers, and (b3) amphoteric polymers In the presence of at least one polymer, crystals of a dicarboxylic acid with 4 carbons are precipitated from an aqueous solution containing a dicarboxylic acid with 4 carbons or its salt. <16> A method for increasing the oil absorption of dicarboxylic acid crystals with a carbon number of 4, which includes the following steps: selected from (b1) nonionic polymer, (b2) cationic polymer, and (b3) amphoteric In the presence of at least one of the polymers, crystals of the dicarboxylic acid with 4 carbons are precipitated from the aqueous solution containing the dicarboxylic acid with 4 carbons or its salt. <17> The method as described in <15> or <16>, wherein the dicarboxylic acid having a carbon number of 4 or its salt is preferably obtained by chemical synthesis derived from petrochemical raw materials. <18> The method as described in any one of <15> to <17>, wherein (b1) the nonionic polymer is preferably selected from starch-based polymers, cellulose-based polymers, and vinyl-based polymers At least one of them is more preferably a vinyl polymer and/or a cellulose polymer obtained by polymerizing a monomer having a vinyl group, and more preferably polyvinyl alcohol and/or hydroxyethyl cellulose. <19> The method as described in any one of <15> to <18>, wherein (b2) the cationic polymer is preferably cationized cellulose. <20> The method as described in any one of <15> to <19>, wherein (b3) the amphoteric polymer is preferably methacryloxyethylphosphocholine-stearyl methacrylate copolymer . <21> The method as described in any one of <15> to <20>, wherein the weight average molecular weight of the polymer is preferably 3,000 or more, more preferably 10,000 or more, still more preferably 30,000 or more, and more preferably It is 2,000,000 or less, more preferably 1,000,000 or less, still more preferably 500,000 or less, more preferably 3,000 or more and 2,000,000 or less, more preferably 10,000 or more and 1,000,000 or less, and still more preferably 30,000 or more and 500,000 or less. <22> The method as described in any one of <15> to <21>, wherein the content of the polymer in the aqueous solution containing a dicarboxylic acid with a carbon number of 4 or its salt is preferably 0.001% by mass or more, and more It is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, more preferably 5% by mass or less, more preferably 1.5% by mass or less, still more preferably 1% by mass or less, and still more preferably 0.5% by mass Hereinafter, it is preferably 0.001 mass% or more and 5 mass% or less, more preferably 0.01 mass% or more and 1.5 mass% or less, still more preferably 0.05 mass% or more and 1 mass% or less, and still more preferably 0.05 mass% % Or more and 0.5% by mass or less. <23> The method described in any one of <15> to <22>, wherein the content of the polymer in the aqueous solution containing the dicarboxylic acid or its salt with 4 carbons is relative to the dicarboxylic acid with 4 carbons The quality of the acid content is preferably 0.001 to 0.5, more preferably 0.002 to 0.3. <24> The method as described in any one of <4> to <23>, which contains the nonionic interfacial activity of (a1) to (a2) in an aqueous solution containing a dicarboxylic acid with a carbon number of 4 or its salt The total content of the agent and the polymer of (b1) to (b3) is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and more preferably 10% by mass or less, It is more preferably 3% by mass or less, still more preferably 2% by mass or less, more preferably 0.001% by mass or more and 10% by mass or less, more preferably 0.01% by mass or more and 3% by mass or less, and still more preferably 0.05 Mass% or more and 2% by mass or less. <25> The method described in any one of <4> to <24>, wherein the method for crystallizing is selected from the group consisting of precipitation by adjusting pH, precipitation by cooling, and precipitation by concentration. One or more methods of precipitation performed and precipitation performed by reaction. <26> The method as described in <25>, wherein the pH value when performing crystallization by adjusting the pH value is preferably 9 or less, more preferably 6 or less, and still more preferably 2.5 or less, and more The pH is preferably 0.5 or more, more preferably 0.5 or more and 9 or less, more preferably 0.5 or more and 6 or less, and still more preferably 0.5 or more and 2.5 or less. <27> The method as described in <25> or <26>, wherein the addition rate of acid during crystallization by adjusting the pH value is preferably 0.1 mmol-acid/L/min or more, more preferably 0.3 mmol-acid/L/min or more, more preferably 1 mmol-acid/L/min or more, more preferably 10 mmol-acid/L/min or less, more preferably 5 mmol-acid/L/min Below, it is more preferably 3 mmol-acid/L/min or less, more preferably 2 mmol-acid/L/min or less, and more preferably 0.1 mmol-acid/L/min or more and 10 mmol-acid/ L/min or less, more preferably 0.3 mmol-acid/L/min or more and 5 mmol-acid/L/min or less, still more preferably 0.3 mmol-acid/L/min or more and 3 mmol-acid/L/min Hereinafter, it is more preferably 1 mmol-acid/L/min or more and 2 mmol-acid/L/min or less. <28> The method as described in <27>, wherein the acid is preferably an inorganic acid, more preferably one or more selected from hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid, and still more preferably sulfuric acid or hydrochloric acid. <29> The method as described in any one of <25> to <28>, wherein the temperature at the time of crystallization by adjusting the pH value is preferably 50°C or less, more preferably 40°C or less, and more preferably 30°C or less, more preferably 0°C or more, more preferably 5°C or more, more preferably 0°C or more and 50°C or less, more preferably 0°C or more and 40°C or less, and still more preferably 5 Above ℃ and below 30℃. <30> The method as described in any one of <25> to <29>, wherein the crystallization is performed by adjusting the pH value in an aqueous solution containing a dicarboxylic acid with 4 carbon atoms or its salt The content of the dicarboxylic acid or its salt with a carbon number of 4 is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 20% by mass or less, and more preferably 1% by mass or more, more preferably It is 2% by mass or more, more preferably 1% by mass or more and 45% by mass or less, more preferably 1% by mass or more and 40% by mass or less, and still more preferably 2% by mass or more and 20% by mass or less. <31> The method as described in <25>, wherein the crystallization by cooling is preferably carried out after raising the temperature of an aqueous solution containing a dicarboxylic acid having a carbon number of 4 or its salt. <32> The method as described in <31>, wherein the temperature rise temperature is preferably 60°C or higher, more preferably 70°C or higher, still more preferably 80°C or higher, more preferably 120°C or lower, and more preferably It is 60°C or higher and 120°C or lower, more preferably 70°C or higher and 120°C or lower, and still more preferably 80°C or higher and 120°C or lower. <33> The method as described in <25>, <31> or <32>, wherein the cooling temperature is preferably 50°C or less, more preferably 40°C or less, still more preferably 30°C or less, and more preferably 0°C or higher, more preferably 5°C or higher, more preferably 0°C or higher and 50°C or lower, more preferably 0°C or higher and 40°C or lower, and still more preferably 5°C or higher and 30°C or lower. <34> The method as described in any one of <31> to <33>, wherein the average cooling rate calculated from the time required from the heating temperature to the cooling temperature is preferably 0.05°C/min or more, more preferably 0.1°C/min or more, more preferably 20°C/min or less, more preferably 10°C/min or less, still more preferably 5°C/min or less, and more preferably 0.05°C/min or more and 20°C /min or less, more preferably 0.1°C/min or more and 10°C/min or less, and still more preferably 0.1°C/min or more and 5°C/min or less. <35> The method as described in any one of <25> and <31> to <34>, wherein the pH value at the time of crystallization by cooling is preferably 4 or less, more preferably 2.5 or less, Furthermore, the pH is preferably 0.5 or more, more preferably 0.5 or more and 4 or less, and more preferably 0.5 or more and 2.5 or less. <36> The method as described in any one of <25>, <31> to <35>, in which an aqueous solution containing a dicarboxylic acid or its salt with 4 carbon atoms when performing crystallization by cooling The content of the dicarboxylic acid with 4 carbon atoms or its salt is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 20% by mass or less, and more preferably 1% by mass or more, It is more preferably 2% by mass or more, more preferably 1% by mass or more and 45% by mass or less, more preferably 1% by mass or more and 40% by mass or less, and still more preferably 2% by mass or more and 20% by mass or less. <37> The method as described in <25>, wherein the crystallization by concentration is carried out by evaporating the solvent of an aqueous solution containing a dicarboxylic acid with 4 carbon atoms or its salt, followed by concentration, and evaporation The temperature at this time is preferably 100°C or less, more preferably 80°C or less, more preferably 5°C or more, more preferably 5°C or more and 100°C or less, more preferably 5°C or more and 80°C or less. <38> The method as described in <25> or <37>, wherein the aqueous solution containing a dicarboxylic acid with 4 carbon atoms or its salt during crystallization by concentration is two of 4 carbon atoms The content of the carboxylic acid or its salt is preferably 45% by mass or less, more preferably 40% by mass or less, still more preferably 20% by mass or less, more preferably 1% by mass or more, more preferably 2% by mass or more, Furthermore, it is preferably 1% by mass or more and 45% by mass or less, more preferably 1% by mass or more and 40% by mass or less, and still more preferably 2% by mass or more and 20% by mass or less. <39> The method as described in <25>, <37> or <38>, wherein the pH value at the time of crystallization by concentration is preferably 4 or less, more preferably 2.5 or less, and more preferably The pH value is 0.5 or more, more preferably 0.5 or more and 4 or less, and more preferably 0.5 or more and 2.5 or less. <40> The method as described in any one of <4> to <39>, wherein crystallization is performed by heating an aqueous solution containing a dicarboxylic acid with 4 carbon atoms or a salt thereof to 80°C or higher, After confirming the dissolution, precipitation by cooling is performed at an average cooling rate of 0.05°C/min or more. After reaching 30°C, inorganic acid is added to lower the pH to 2.5 or less. <41> The method as described in any one of <4> to <40>, wherein the dicarboxylic acid crystals with carbon number 4 are preferably fumaric acid, succinic acid, malic acid, tartaric acid, and maleic acid Diacid or oxalic acid crystals are more preferably fumaric acid or succinic acid crystals, and still more preferably fumaric acid crystals. <42> The method described in <25>, wherein the crystals of dicarboxylic acid with 4 carbon atoms are fumaric acid crystals. The medium undergoes a reaction to produce fumaric acid and crystallizes out. <43> The method as described in <42>, wherein the content of maleic acid or maleic anhydride in the aqueous solution containing maleic acid or maleic anhydride is preferably 5% by mass or more, It is more preferably 10% by mass or more, more preferably 20% by mass or more, more preferably 70% by mass or less, more preferably 50% by mass or less, more preferably 40% by mass or less, and still more preferably 30% by mass or less, Furthermore, it is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 50% by mass or less, still more preferably 10% by mass or more and 40% by mass or less, and still more preferably 20% by mass or more And 30% by mass or less. <44> The method as described in <42> or <43>, wherein the catalyst is preferably thiourea, bromate, or perborate. <45> In the method described in any one of <4> to <44>, the peripheral speed of one side is preferably 0.2 m/s or more, more preferably 0.3 m/s or more, and still more preferably The speed is 0.5 m/s or more, more preferably the peripheral speed is 10 m/s or less, more preferably the peripheral speed is 5 m/s or less, further preferably the peripheral speed is 3 m/s or less, and more preferably the peripheral speed 0.2 m/s or more and 10 m/s or less, more preferably a peripheral speed of 0.3 m/s or more and 5 m/s or less, and still more preferably a peripheral speed of 0.5 m/s or more and 3 m/s or less while stirring Carry out crystallization. <46> The method described in any one of <4> to <45>, wherein the dicarboxylic acid crystal with carbon number 4 has an oil absorption measured in accordance with JIS K 5101-13-2 (2004) 40 mL/100 g～200 mL/100 g, more preferably 50 mL/100 g～200 mL/100 g, still more preferably 60 mL/100 g～200 mL/100 g, still more preferably 70 mL/100 g 100 g～200 mL/100 g. [Example] [C4 Dicarboxylic acid] ・Fumaric acid: manufactured by Nippon Shokubai Co., Ltd. ・Fumaric acid: manufactured by Kawasaki Kasei Co., Ltd. ・Succinic acid: Wako Pure Chemical Industries, Ltd. Manufacturing ・DL-malic acid: manufactured by Wako Pure Chemical Industries Co., Ltd.・Maleic acid: manufactured by Wako Pure Chemical Industries, Ltd. [surfactant] (nonionic surfactant) ・Polyoxyethylene (2.5) Lauryl ether: Emulgen (registered trademark) 102, HLB 6.8, manufactured by Kao Co., Ltd. · Polyoxyethylene (4) Lauryl ether: Emulgen 104, HLB 8.6, manufactured by Kao Co., Ltd. · Polyoxyethylene (6) stearyl ether: Emulgen 306P, HLB 8.3, manufactured by Kao Corporation ・Sorbitan monolaurate: Emsol (registered trademark) L-10V, HLB 10.8, manufactured by Kao Corporation ・Sorbitan monostearate: Emsol S-10V, HLB 8.1, manufactured by Kao Corporation ・Lauryl glycoside: MYDOL (registered trademark) 12 (40% active ingredient), HLB 12.5, manufactured by Kao Corporation ・Polyoxyethylene (40) sorbitol four oil Ester: RHEODOL 440V, HLB 9.9, manufactured by Kao Corporation·Polyoxyethylene (30) sorbitol tetraoleate: RHEODOL 430V, HLB 8.6, manufactured by Kao Corporation·Polyoxyethylene (20) sorbitol Anhydride trioleate: RHEODOL TW-O320V, HLB 8.0, manufactured by Kao Corporation ・Polyoxyethylene (6) Laureth: Emulgen 108, HLB 10.3, manufactured by Kao Corporation (comparative example) ・Polyoxyethylene (47) ) Lauryl ether: Emulgen 150, HLB 16.8, manufactured by Kao (comparative example) ・Polyoxyethylene (20) sorbitan monolaurate: Emsol L-120V, HLB 14.9, manufactured by Kao (comparative) Example) (Anionic surfactant) ・Sodium lauryl sulfate (Emal (registered trademark) 0, manufactured by Kao Co., Ltd.) (Comparative example) (Cation surfactant) ・Cetyl trimethylammonium bromide (Wako Pure Pharmaceutical Industry (manufactured by Co., Ltd.) (comparative example) The HLB described above is a value calculated based on the inorganic and organic values of Oda, Teramura, etc., described above. [Polymer] (Non-ionic polymer) ・Polyvinylpyrrolidone K30 (manufactured by Wako Pure Chemical Industries, Ltd.) ・Polyvinyl alcohol (weight average molecular weight 100,000, manufactured by MP Biomedical) ・Hydroxyethyl cellulose ( 200～300 mPa·s, 2% aqueous solution at 20℃, manufactured by Tokyo Chemical Industry Co., Ltd. (Cationic polymer) ・Hydroxyethylcellulose hydroxypropyltrimethylammonium chloride: Poiz (registered trademark) ) C-60H, manufactured by Kao Co., Ltd. (Amphoteric polymer) ・Methacryloxyethyl phosphocholine-stearyl methacrylate copolymer: Lipidure (registered trademark) NR (polymer concentration 5%) , Manufactured by NOF Corporation (anionic polymer) ・Polyacrylic acid (weight average molecular weight 250,000) (manufactured by Wako Pure Chemical Industries, Ltd.) (comparative example) [Measurement of oil absorption] Regarding oil absorption, according to JIS K 5101 -13-2, take a sample of 1～5 g and place it on the center of the measuring plate (smooth glass plate with a size greater than 300×400 mm), and slowly add 4 or 5 drops of boiled linseed oil from the burette Drop to the center of the sample, and use a flat spatula each time to fully knead the whole. Repeat the dripping and kneading of boiled linseed oil until the whole becomes a hard putty-like lump, then knead it drop by drop, and it will become a state where it can be rolled into a spiral shape with a flat spatula after the last drop is dropped. For the end. Among them, when it cannot be rolled into a spiral shape, the end is set as the end point just before the sudden softening due to boiling 1 drop of linseed oil. The operation is adjusted so that the operation time until the end point is between 7 and 15 minutes. Read the dripping amount of boiled linseed oil in the burette when the end point is reached, and set it as the oil absorption (unit: mL per 100 g of the sample). [Comparative Example 1] The oil absorption of fumaric acid manufactured by Kawasaki Chemical Industry Co., Ltd. was measured, and the result was 29.5 mL/100 g. [Comparative Example 2] The oil absorption of fumaric acid manufactured by Nippon Shokubai Co., Ltd. was measured, and the result was 29.4 mL/100 g. [Comparative Example 3] The oil absorption of succinic acid manufactured by Wako Pure Chemical Industries, Ltd. was measured, and the result was 27.3 mL/100 g. [Comparative Example 4] The oil absorption of DL-malic acid manufactured by Wako Pure Chemical Industries, Ltd. was measured, and the result was 28.0 mL/100 g. [Comparative Example 5] The oil absorption of maleic acid manufactured by Wako Pure Chemical Industries, Ltd. was measured, and the result was 25.2 mL/100 g. [Comparative Example 6] By using a high-speed mixer PICCOLO SMP2 (manufactured by Kawada Co., Ltd.), stirring at a wing diameter of 140 mm and a speed of 3000 r/min for 20 minutes, Acrylic acid crushed. The oil absorption of the crushed fumaric acid was measured, and the result was 36.6 mL/100 g. The results of Comparative Examples 1 to 6 are shown in Table 1. [Table 1] (Precipitation by cooling) [Example 1] 16.7 kg of ion-exchanged water and fumaric acid (manufactured by Nippon Shokubai Co., Ltd.) were prepared in a 35 L reaction tank (diameter 360 mm). The same up to Example 13) 817 g and polyoxyethylene (2.5) lauryl ether (Emulgen 102) 17.5 g were mixed, and the mixture was heated to 85°C to be dissolved. Then, it was cooled from 85°C to 23°C at an average cooling rate of 0.79°C/min, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Next, use No. 2 filter paper (manufactured by ADVANTEC Co., the same below) to suction and filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion-exchanged water for filtration and washing. The pH of the filtrate was 2.2. A hot-air circulation dryer FS-60WT (manufactured by Tokyo Glass Instruments Co., Ltd., the same below) was used to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 61.9 mL/100 g. [Example 2] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of polyoxyethylene (4) lauryl ether (Emulgen 104) in a 35 L reaction tank (diameter 360 mm), The temperature was raised to 85°C for dissolution. Then, it was cooled from 85 degreeC to 23 degreeC at an average cooling rate of 0.63 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as in Example 1. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 69.4 mL/100 g. [Example 3] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 of polyoxyethylene (40) sorbitol tetraoleate (RHEODOL 440V) After g is mixed, the temperature is raised to 85°C to dissolve. Then, it was cooled from 85 degreeC to 24 degreeC at an average cooling rate of 0.86 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as in Example 1. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 50.1 mL/100 g. [Example 4] After mixing 2.14 kg of ion-exchanged water and 105 g of fumaric acid in a 3 L reaction tank (diameter 130 mm), the temperature was raised to 85°C to dissolve. Then, 2.25 g of polyoxyethylene (6) stearyl ether (Emulgen 306P) was mixed, and then cooled from 85°C to 25°C at an average cooling rate of 0.45°C/min to precipitate fumaric acid. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 250 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 500 g of ion exchange water to filter and wash. The pH of the filtrate was 2.2. A hot air circulation dryer FS-60WT (manufactured by Tokyo Glass Instruments Co., Ltd.) was used to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 75.1 mL/100 g. [Example 5] After mixing 2.14 kg of ion-exchanged water and 105 g of fumaric acid in a 3 L reaction tank (diameter 130 mm), the temperature was raised to 85°C for dissolution. Then, after mixing 2.25 g of polyoxyethylene (6) stearyl ether (Emulgen 306P), the mixture was cooled from 85°C to 26°C at an average cooling rate of 0.094°C/min to precipitate fumaric acid. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 250 r/min. The operation after crystallization was the same as in Example 4. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 85.6 mL/100 g. [Example 6] In a 3 L reaction tank (130 mm in diameter), ion-exchange water 2.57 kg, fumaric acid 105 g, 47% sulfuric acid (manufactured by Wako Pure Chemical Industries Co., Ltd.) 50 g, poly After mixing 27.5 g of oxyethylene (20) sorbitan trioleate (RHEODOL TW-O320V), the temperature was raised to 80°C and dissolved. Then, it cooled from 80 degreeC to 28 degreeC at an average cooling rate of 0.64 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 100 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 500 g of ion exchange water to filter and wash. The pH of the filtrate was 0.99. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 75.8 mL/100 g. [Example 7] In a 3 L reaction tank (130 mm in diameter), 2.52 kg of ion-exchange water, 158 g of fumaric acid, and 72.5 g of sodium fumarate (manufactured by Tokyo Chemical Industry Co., Ltd.) After 2.75 g of polyoxyethylene (30) sorbitol tetraoleate (RHEODOL 430V) was mixed, the temperature was raised to 80°C and dissolved. Then, it was cooled from 80 degreeC to 27 degreeC at an average cooling rate of 0.39 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 500 g of ion exchange water to filter and wash. The pH of the filtrate was 3.6. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 59.2 mL/100 g. [Example 8] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion exchange water, 817 g of fumaric acid, and 17.5 g of sorbitan monolaurate (Emasol L-10V) were mixed. After that, the temperature was raised to 85°C for dissolution. Then, it was cooled from 85°C to 22°C at an average cooling rate of 1.06°C/min, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as in Example 1. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 79.5 mL/100 g. [Example 9] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion-exchange water, 817 g of fumaric acid, and 17.5 g of sorbitan monostearate (Emasol S-10V) were added. After mixing, the temperature was raised to 85°C for dissolution. Then, it was cooled from 85 degreeC to 24 degreeC at an average cooling rate of 0.89 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as in Example 1. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 49.6 mL/100 g. [Example 10] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion-exchange water, 817 g of fumaric acid, and 1.75 g of sorbitan monolaurate (Emasol L-10V) were mixed. After that, the temperature was raised to 85°C for dissolution. Then, it was cooled from 85°C to 25°C at an average cooling rate of 0.70°C/min, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.0. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 51.7 mL/100 g. [Example 11] In a 100 L reaction tank (diameter 450 mm), 80.0 kg of ion-exchange water, 6.31 kg of fumaric acid, and 86.4 g of lauryl glucoside (MYDOL 12) were mixed, and the temperature was raised to 92°C And dissolve. Then, it cooled from 92 degreeC to 21 degreeC at an average cooling rate of 0.34 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 24.6 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.3. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 51.5 mL/100 g. [Example 12] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of polyvinylpyrrolidone (polyvinylpyrrolidone K30) in a 35 L reaction tank (diameter 360 mm) , The temperature was raised to 85°C for dissolution. Then, it was cooled from 85 degreeC to 22 degreeC at an average cooling rate of 1.0 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.3. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 54.9 mL/100 g. [Example 13] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion exchange water, 817 g of fumaric acid, and 175 g of polyvinylpyrrolidone (polyvinylpyrrolidone K30) were mixed together , The temperature was raised to 85°C for dissolution. Then, it was cooled from 85°C to 23°C at an average cooling rate of 0.72°C/min, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.2. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 40.3 mL/100 g. [Example 14] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion-exchange water, 817 g of fumaric acid, and 1.75 g of polyvinyl alcohol (molecular weight: 100000) were mixed, and the temperature was raised to 85°C. Dissolve. Then, it cooled from 85 degreeC to 23 degreeC at an average cooling rate of 0.68 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.1. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 62.9 mL/100 g. [Example 15] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of polyvinyl alcohol (molecular weight 100,000) in a 35 L reaction tank (diameter 360 mm), the temperature was raised to 85°C. Dissolve. Then, it was cooled from 85°C to 25°C at an average cooling rate of 0.39°C/min, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.2. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 158.6 mL/100 g. [Example 16] In a 3 L reaction tank (130 mm in diameter), 2.64 kg of ion-exchange water, 105 g of fumaric acid, and hydroxyethyl cellulose hydroxypropyltrimethylammonium chloride (Poiz C -60H) After mixing 2.75 g, the temperature was raised to 80°C to dissolve. Then, it was cooled from 80 degreeC to 28 degreeC at an average cooling rate of 0.55 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to suction and filter the precipitated fumaric acid suspension. The pH of the filtrate was 2.2. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 50.1 mL/100 g. [Example 17] In a 3 L reaction tank (diameter 360 mm), 2.59 kg of ion-exchanged water, 105 g of fumaric acid, and methacryloxyethyl phosphocholine-stearyl methacrylate were prepared After 55 g of the copolymer (Lipidure NR) was mixed, the temperature was raised to 80°C and dissolved. Then, it was cooled from 80 degreeC to 30 degreeC at an average cooling rate of 0.68 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to suction and filter the precipitated fumaric acid suspension. The pH of the filtrate was 2.2. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 51.9 mL/100 g. The conditions and results of Examples 1-17 are shown in Table 2 and Table 3. [Example 18] In a 3 L reaction tank (diameter 360 mm), ion exchange water 2.59 kg, fumaric acid 105 g, and hydroxyethyl cellulose (hydroxyethyl cellulose 200-300 mPa·s) 1.13 After g is mixed, the temperature is raised to 80°C to dissolve. Then, it was cooled from 80 degreeC to 25 degreeC at an average cooling rate of 0.60 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 250 r/min. Secondly, use No. 2 filter paper to suction and filter the precipitated fumaric acid suspension. The pH of the filtrate was 2.2. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 115.0 mL/100 g. [Table 2] [table 3] [Comparative Example 7] After mixing 16.7 kg of ion-exchanged water and 817 g of fumaric acid in a 35 L reaction tank (diameter 360 mm), the temperature was raised to 85°C to dissolve the fumaric acid. Then, it was cooled from 85 degreeC to 23 degreeC at an average cooling rate of 0.98 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.3. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 25.4 mL/100 g. [Comparative Example 8] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of polyoxyethylene (47) lauryl ether (Emulgen 150) in a 35 L reaction tank (diameter 360 mm), The temperature was raised to 85°C for dissolution. Then, it cooled from 85 degreeC to 23 degreeC at an average cooling rate of 0.56 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.2. A hot air circulation dryer FS-60WT (manufactured by Tokyo Glass Instruments Co., Ltd.) was used to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 24.4 mL/100 g. [Comparative Example 9] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of polyoxyethylene (6) lauryl ether (Emulgen 108) in a 35 L reaction tank (diameter 360 mm), The temperature was raised to 85°C for dissolution. Then, it cooled from 85 degreeC to 25 degreeC at an average cooling rate of 0.63 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as that of Comparative Example 8. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 38.7 mL/100 g. [Comparative Example 10] In a 35 L reaction tank (diameter 360 mm), 16.7 kg of ion-exchange water, 817 g of fumaric acid, and polyoxyethylene (20) sorbitan monolaurate (Emasol L- 120V) After mixing 17.5 g, the temperature was raised to 85°C and dissolved. Then, it cooled from 85 degreeC to 25 degreeC at an average cooling rate of 0.87 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as that of Comparative Example 8. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 33.7 mL/100 g. [Comparative Example 11] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of sodium lauryl sulfate (Emal 0) in a 35 L reaction tank (diameter 360 mm), the temperature was raised to 85°C And dissolve. Then, it was cooled from 85 degreeC to 25 degreeC at an average cooling rate of 0.94 degreeC/min, and fumaric acid was precipitated by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as that of Comparative Example 8. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 22.8 mL/100 g. [Comparative Example 12] After mixing 16.7 kg of ion-exchanged water, 817 g of fumaric acid, and 17.5 g of cetyltrimethylammonium bromide in a 35 L reaction tank (diameter 360 mm), the temperature was raised to 85. ℃ and dissolve. Then, it cooled from 85 degreeC to 23 degreeC at an average cooling rate of 0.46 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. The operation after crystallization was the same as that of Comparative Example 8. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 39.1 mL/100 g. [Comparative Example 13] After mixing 2.09 kg of ion-exchanged water, 105 g of fumaric acid, and 0.034 g of polyacrylic acid (molecular weight 250,000) in a 3 L reaction tank (diameter 130 mm), the temperature was raised to 80°C. Dissolve. Then, it cooled from 80 degreeC to 24 degreeC at an average cooling rate of 0.23 degreeC/min, and precipitated fumaric acid by this. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 500 g of ion exchange water to filter and wash. The pH of the filtrate was 2.1. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 26.8 mL/100 g. Table 4 shows the results of Comparative Examples 7-13. [Table 4] As described in Tables 1 to 4 above, it was confirmed that the fumaric acid crystals crystallized by the method of the present invention showed high oil absorption. (Precipitation method by adjusting pH) [Example 19] In an 80 L reaction tank, 33.7 kg of ion-exchanged water and fumaric acid (manufactured by Kawasaki Chemical Industry Co., Ltd.) 1.87 kg, 48% Sodium hydroxide 1.89 kg and polyoxyethylene (40) sorbitol tetraoleate (RHEODOL 440V) 37.5 g are mixed to dissolve fumaric acid. The pH of the solution is 4.0. Then, 47% sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added at an average acid addition rate of 1.82 mmol-H 2 SO 4 /L/min until the pH became 2.1, thereby depositing fumaric acid. The stirring system uses a stirring blade with a blade diameter of 150 mm and is carried out under the condition of 300 r/min. Secondly, use No. 2 filter paper to filter the precipitated fumaric acid suspension, and then add 5.0 kg of ion exchange water to filter and wash. The pH of the filtrate was 2.1. Use the hot air circulation dryer FS-60WT to dry the filtered fumaric acid filter cake at 105°C. After drying, the fumaric acid crystals were obtained by passing through a sieve with an opening of 500 μm. The oil absorption of the obtained fumaric acid crystals was measured, and the result was 72.5 mL/100 g. The results of Example 19 are shown in Table 5. [table 5] As shown in Table 5 above, it was confirmed that fumaric acid crystals with high oil absorption can be obtained even by adjusting the pH value for crystallization. (Precipitation method by cooling) [Example 20] After mixing 1.81 kg of ion-exchanged water and 450 g of succinic acid (manufactured by Wako Pure Chemical Industries, Ltd., the same below) in a 3 L reaction tank, The temperature was raised to 80°C. Then, 9.64 g of polyoxyethylene (6) stearyl ether (Emulgen 306P) was mixed, and then cooled from 80°C to 26°C at an average cooling rate of 0.27°C/min to precipitate succinic acid. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to suction and filter the precipitated succinic acid suspension. The pH of the filtrate was 2.1. Use hot air circulation dryer FS-60WT to dry the filtered succinic acid filter cake at 105°C. After drying, succinic acid crystals were obtained by passing through a sieve with a mesh of 710 μm. The oil absorption of the obtained succinic acid crystals was measured, and the result was 58.6 mL/100 g. [Example 21] After mixing 1.80 kg of ion-exchanged water and 450 g of succinic acid in a 3 L reaction tank, the temperature was raised to 80°C. Then, after mixing 2.25 g of polyvinyl alcohol (molecular weight: 100,000), the mixture was cooled from 80°C to 26°C at an average cooling rate of 0.42°C/min to precipitate succinic acid. The stirring system uses a stirring blade with a blade diameter of 121 mm and is carried out under the condition of 150 r/min. Secondly, use No. 2 filter paper to suction and filter the precipitated succinic acid suspension. The pH of the filtrate was 2.0. Use hot air circulation dryer FS-60WT to dry the filtered succinic acid filter cake at 105°C. After drying, succinic acid crystals were obtained by passing through a sieve with a mesh of 500 μm. The oil absorption of the obtained succinic acid crystals was measured, and the result was 115.7 mL/100 g. The results of Examples 20 and 21 are shown in Table 6. [Table 6] As described in Table 6 above, it was confirmed that the succinic acid crystals crystallized by the method of the present invention showed high oil absorption.
