於本說明書中，所謂「基於單體之單元」係藉由單體1分子進行聚合而直接形成之原子團、與藉由使該原子團之一部分進行化學轉換而獲得之原子團之總稱。再者，以下，基於單體之單元亦簡稱為「單元」。 含氟聚合物所具有之各單元之含量(莫耳%)可藉由核磁共振譜法分析含氟聚合物而求出，亦可根據各單體之添加量進行推算。 所謂「交聯性基」意指藉由與硬化劑進行反應而可形成交聯結構之基、或交聯性基彼此進行反應而可形成交聯結構之基。 所謂「硬化劑」意指具有2個以上可與「交聯性基」進行反應之基且藉由與交聯性基進行反應而可形成交聯結構之化合物。 所謂「(甲基)丙烯酸酯」為丙烯酸酯及甲基丙烯酸酯之總稱。 本發明之水性分散液係具有基於氟烯烴之單元及基於具有交聯性基之單體之單元的含氟聚合物分散於水性介質中而成者，其含有選自由過硫酸鹽及其分解物所組成之群之至少一種成分(以下亦稱為「鹽成分」)，且鹽成分之含量相對於含氟聚合物100 g，以過硫酸鹽換算計為0.01～0.22 mmol。 本發明之水性分散液係藉由下文所述之水性分散液之製造方法中所說明之聚合法而獲得之水性分散液。因此，本發明之水性分散液至少含有水性介質、含氟聚合物及鹽成分，除了該等以外亦可含有聚合時所使用之成分。作為聚合時所使用之成分，可列舉下文所述之水性分散液之製造方法中所說明之乳化劑、鏈轉移劑等。 作為本發明中之水性介質，為水、或水與水溶性有機溶劑之混合物。 作為水溶性有機溶劑，可列舉：第三丁醇、丙二醇、二丙二醇、二丙二醇單甲醚、三丙二醇等。 若水性介質含有水溶性有機溶劑，則聚合時單體於水性介質中之分散性、及所產生之含氟聚合物之分散性提高，生產性提高。 水溶性有機溶劑之含量相對於水100質量份，較佳為1～40質量份，更佳為3～30質量份。 本發明中之含氟聚合物具有基於氟烯烴(以下亦稱為「單體1」)之單元(以下亦稱為「單元1」)及基於具有交聯性基之單體(以下亦稱為「單體2」)之單元(以下亦稱為「單元2」)。 含氟聚合物亦可視需要進一步具有基於單體1及單體2以外之單體(以下亦稱為「單體3」)之單元(以下亦稱為「單元3」)。 水性分散液中之含氟聚合物之含量相對於水性分散液之總質量，較佳為10～70質量%，尤佳為20～60質量%。若含氟聚合物之含量為上述下限值以上，則迅速進行聚合，可獲得較高之反應率。另一方面，若為上限值以下，則水性分散液中之含氟聚合物之分散穩定性、及其著色穩定性更優異。 本發明中之單體1係烯烴之1個以上之氫原子經氟原子取代之化合物。於單體1中，未經氟原子取代之1個以上之氫原子可經氯原子取代。 作為單體1，較佳為CF2
=CF2
、CF2
=CFCl、CF2
=CHF、CH2
=CF2
、CF2
=CFCF3
及CF2
=CHCF3
，就所獲得之塗膜之耐候性之方面而言，更佳為CF2
=CF2
及CF2
=CFCl，尤佳為CF2
=CFCl。 單體1亦可併用兩種以上。 本發明中之單體2之交聯性基較佳為羥基、水解性矽烷基、羧基、胺基、異氰酸基、環氧基或氧雜環丁基，尤佳為羥基或羧基。 作為交聯性基為羥基之單體2(具有羥基之單體)，可列舉：羥基烷基乙烯基醚(羥基乙基乙烯基醚、羥基丁基乙烯基醚等)、具有羥基與乙烯氧基之環烷烴(環己烷二甲醇單乙烯醚等)、乙二醇單乙烯醚(二乙二醇單乙烯醚、三乙二醇單乙烯醚、四乙二醇單乙烯醚等)、羥基烷基烯丙基醚(羥基乙基烯丙基醚、羥基丁基烯丙基醚等)、具有羥基與烯丙氧基之環烷烴(環己烷二甲醇單烯丙醚等)、羥基烷基乙烯基酯(羥基乙基羧酸乙烯酯、羥基丁基羧酸乙烯酯等)、具有羥基與乙烯氧基羰基之環烷烴(((羥基甲基環己基)甲氧基)乙酸乙烯酯等)、羥基烷基羧酸烯丙酯(羥基乙基羧酸烯丙酯、羥基丁基羧酸烯丙酯等)、具有羥基與烯丙氧基羰基之環烷烴(((羥基甲基環己基)甲氧基)乙酸烯丙酯等)、(甲基)丙烯酸羥基烷基酯((甲基)丙烯酸羥基乙酯等)。作為具有羥基之單體，較佳為羥基烷基乙烯基醚及羥基烷基烯丙基醚，尤佳為羥基烷基乙烯基醚。 作為交聯性基為羧基之單體2(具有羧基之單體)，可列舉：不飽和單羧酸(3-丁烯酸、4-戊烯酸、2-己烯酸、3-己烯酸、5-己烯酸、2-庚烯酸、3-庚烯酸、6-庚烯酸、3-辛烯酸、7-辛烯酸、2-壬烯酸、3-壬烯酸、8-壬烯酸、9-癸烯酸、10-十一烯酸、丙烯酸、甲基丙烯酸、丁烯酸、桂皮酸等)、飽和單羧酸乙烯基醚(乙烯氧基戊酸、3-乙烯氧基丙酸、3-(2-乙烯氧基丁氧基羰基)丙酸、3-(2-乙烯氧基乙氧基羰基)丙酸等)、飽和單羧酸烯丙基醚(烯丙氧基戊酸、3-烯丙氧基丙酸、3-(2-烯丙氧基丁氧基羰基)丙酸、3-(2-烯丙氧基乙氧基羰基)丙酸等)、飽和多元羧酸單乙烯酯(己二酸單乙烯酯、琥珀酸單乙烯酯、鄰苯二甲酸乙烯酯、均苯四甲酸乙烯酯等)、不飽和二羧酸或其分子內酸酐(伊康酸、順丁烯二酸、反丁烯二酸、順丁烯二酸酐、伊康酸酐等)、不飽和羧酸單酯(伊康酸單酯、順丁烯二酸單酯、反丁烯二酸單酯等)。作為具有羧基之單體，較佳為不飽和單羧酸，較佳為10-十一烯酸及丁烯酸。 作為交聯性基為水解性矽烷基之單體2(具有水解性矽烷基之單體)，可列舉：(CH2
=CHC(O)O(CH2
)3
Si(OCH3
)3
、CH2
=CHC(O)O(CH2
)3
Si(OC2
H5
)3
、CH2
=C(CH3
)C(O)O(CH2
)3
Si(OCH3
)3
、CH2
=C(CH3
)C(O)O(CH2
)3
Si(OC2
H5
)3
、CH2
=CHC(O)O(CH2
)3
SiCH3
(OC2
H5
)2
、CH2
=C(CH3
)C(O)O(CH2
)3
SiC2
H5
(OCH3
)2
、CH2
=C(CH3
)C(O)O(CH2
)3
Si(CH3
)2
(OC2
H5
)、CH2
=C(CH3
)C(O)O(CH2
)3
Si(CH3
)2
OH、CH2
=CHC(O)O(CH2
)3
Si(OCOCH3
)3
、CH2
=C(CH3
)C(O)O(CH2
)3
SiC2
H5
(OCOCH3
)2
、CH2
=C(CH3
)C(O)O(CH2
)3
SiCH3
(N(CH3
)COCH3
)2
、CH2
=CHC(O)O(CH2
)3
SiCH3
[ON(CH3
)C2
H5
]2
、CH2
=C(CH3
)C(O)O(CH2
)3
SiC6
H5
[ON(CH3
)C2
H5
]2
等具有水解性矽烷基之(甲基)丙烯酸酯；CH2
=CHSi[ON=C(CH3
)(C2
H5
)]3
、CH2
=CHSi(OCH3
)3
、CH2
=CHSi(OC2
H5
)3
、CH2
=CHSiCH3
(OCH3
)2
、CH2
=CHSi(OCOCH3
)3
、CH2
=CHSi(CH3
)2
(OC2
H5
)、CH2
=CHSi(CH3
)2
SiCH3
(OCH3
)2
、CH2
=CHSiC2
H5
(OCOCH3
)2
、CH2
=CHSiCH3
[ON(CH3
)C2
H5
]2
、CH2
=CHSiCl3
等乙烯基矽烷；具有水解性矽烷基之乙烯基醚。具有水解性矽烷基之單體亦可為部分水解之縮合物。 作為交聯性基為胺基之單體2(具有胺基之單體)，可列舉：胺基烷基乙烯基醚、胺基烷基乙烯基酯、胺基甲基苯乙烯、乙烯胺、丙烯醯胺、乙烯基乙醯胺、乙烯基甲醯胺等。 作為交聯性基為異氰酸基之單體2(具有異氰酸基之單體)，可列舉：甲基丙烯酸2-異氰酸基乙酯、丙烯酸2-異氰酸基乙酯、乙氧基甲基丙烯酸2-異氰酸基乙酯、2-異氰酸基乙基乙烯基醚等。 作為交聯性基為環氧基之單體2(具有環氧基之單體)，可列舉：縮水甘油基乙烯基醚、甲基丙烯酸縮水甘油酯、甲基丙烯酸3,4-環氧環己基甲酯、3,4-環氧環己基甲基乙烯基醚、4-乙烯氧基甲基環己基縮水甘油醚等。 作為其他單體2之較佳之例示，可列舉具有交聯性基與親水性部位之單體(以下亦稱為「巨單體」)。 所謂親水性部位意指具有親水性基之部位或具有親水性鍵之部位、或包含該等部位之組合之部位。作為親水性基，可為離子性、非離子性、兩性之任一者。 就水性分散液之化學穩定性之方面而言，較佳為組合具有非離子性或兩性之親水性基之部位與具有其他親水性基之部位、或組合具有親水性基之部位與具有親水性鍵之部位。 作為巨單體之具體例，可列舉J-Q-[O-Y-]n
-OR所表示之化合物、J-Q-O(C(O)-Z-O-)m
R所表示之化合物等(其中，各式中，J表示乙烯氧基或烯丙氧基，Q表示碳數1～10之伸烷基或碳數6～10之具有環結構之伸烷基，Y表示碳數1～4之伸烷基，R表示氫原子，n表示2～20之整數，Z表示碳數1～10之伸烷基，m表示1～30之整數；以下相同)。 -[O-Y-]-所表示之基較佳為氧伸乙基(即，Y為二亞甲基)。又，-[O-Y-]n
-所表示之親水性部位可含有兩種以上之-[O-Y-]-所表示之基(例如-OCH2
CH2
-與-OCH2
CH(CH3
)-)。含有兩種以上基之情形時之各基可以嵌段、無規之任一類型排列。 作為巨單體，較佳為J-Q-[O-Y-]n
-OH所表示之化合物(其中，J、Q、n如上所述；Y為碳數2～4之伸烷基(其中，n個Y之至少一部分為二亞甲基))。於Y為二亞甲基以外之伸烷基之情形時，較佳為-CH2
CH(CH3
)-。較佳為n個Y之50%以上為二亞甲基，更佳為80～100%為二亞甲基。 又，巨單體亦可為具有親水性之乙烯性不飽和單體進行自由基聚合而成之鏈、且於單個末端具有乙烯氧基或烯丙氧基等自由基聚合性不飽和基之單體。 該巨單體可藉由Polym. Bull., 5.335(1981)所記載之方法而製造。即如下方法：於具有可縮合之官能基之聚合起始劑及鏈轉移劑之存在下，使具有親水性基之乙烯性不飽和單體進行自由基聚合而製造具有可縮合之官能基之聚合物。繼而，使該聚合物之官能基與縮水甘油基乙烯基醚、縮水甘油基烯丙基醚等化合物進行反應，而對末端導入自由基聚合性不飽和基。 作為乙烯性不飽和單體，可列舉：丙烯醯胺、甲基丙烯醯胺、N-羥甲基丙烯醯胺、N-羥甲基甲基丙烯醯胺、(甲基)丙烯酸2-甲氧基乙酯、二丙酮丙烯醯胺、(甲基)丙烯酸羥基乙酯、(甲基)丙烯酸羥基丙酯、(甲基)丙烯酸羥基丁酯及乙烯基吡咯啶酮等。 單體2亦可併用兩種以上。 本發明中之單體3並無特別限定，可列舉：烯烴(乙烯、丙烯等)、烷基乙烯基醚(乙基乙烯基醚、丙基乙烯基醚、丁基乙烯基醚、2-乙基己基乙烯基醚等)、環烷基乙烯基醚(環己基乙烯基醚等)、烷基乙烯基酯(丁酸乙烯酯、辛酸乙烯酯、新戊酸乙烯酯等)、烷基烯丙基酯(丁酸烯丙酯、辛酸烯丙酯、新戊酸烯丙酯等)、芳香族乙烯(苯乙烯、乙烯基甲苯等)、烯丙基醚(乙基烯丙基醚等)、(甲基)丙烯酸酯((甲基)丙烯酸甲酯、(甲基)丙烯酸丁酯等)。作為單體3，較佳為烷基乙烯基醚、環烷基乙烯基醚及烷基乙烯基酯。 又，作為其他單體3，可列舉作為上文所述之J-Q-[O-Y-]n
-OR所表示之化合物、或J-Q-O(C(O)-Z-O)m
R所表示之化合物且R被取代為碳數1～3之烷基之化合物。 本發明中之含氟聚合物較佳為具有基於CF2
=CF2
或CF2
=CFCl之單元作為單元1、具有基於羥基烷基乙烯基醚或CH2
=CHO-Q-[O-Y-]n
-OH所表示之化合物之單元作為單元2之聚合物，或者具有基於CF2
=CF2
或CF2
=CFCl之單元作為單元1、具有基於羥基烷基乙烯基酯或CH2
=CHCH2
O-Q-[O-Y-]n
-OH所表示之化合物之單元作為單元2之聚合物。 於本發明中之含氟聚合物中，單元1之含量(莫耳%)相對於單元2之含量(莫耳%)之比率(單元1之含量/單元2之含量)較佳為0.5～800，更佳為1.5～300。若該比率處於該範圍，則不僅水性分散液中之分散性進一步提高，而且所獲得之塗膜之耐候性、耐水性變得更良好。 於本發明中之含氟聚合物進而含有單元3之情形時，單元3之含量相對於單元1與單元2之總含量之比率(單元3之含量/單元1之含量與單元2之含量之和)較佳為0.1～1.5。 含氟聚合物中之單元1之含量相對於含氟聚合物所具有之全部單元，較佳為30～70莫耳%，更佳為35～65莫耳%，進而較佳為40～60莫耳%。 含氟聚合物中之單元2之含量相對於含氟聚合物所具有之全部單元，較佳為0.5～30莫耳%，更佳為1.0～20莫耳%，進而較佳為1.5～15莫耳%。 含氟聚合物中之單元3之含量相對於含氟聚合物所具有之全部單元，較佳為20～70莫耳%，更佳為25～65莫耳%，進而較佳為30～60莫耳%。 作為本發明中之含氟聚合物之較佳之具體例，可列舉相對於聚合物之全部單元之合計量，具有29.5～70莫耳%之單元1、0.5～30莫耳%之單元2及20～70莫耳%之單元3之聚合物，作為更佳之具體例，可列舉具有34～65莫耳%之單元1、1.0～20莫耳%之單元2及25～65莫耳%之單元3之聚合物。 於本發明之水性分散液中，含氟聚合物較佳為以粒子狀分散於水性介質中。以粒子狀分散之含氟聚合物之平均粒徑較佳為200 nm以下，尤佳為180 nm以下。下限值通常為50 nm。於平均粒徑為200 nm以下之情形時，水性分散液之著色穩定性之效果變得顯著。其原因未必明確，但認為如以下所述。 認為分散於水性分散液中之含氟聚合物之粒子之平均粒徑越小，含氟聚合物之粒子與源自鹽成分之著色成分之相互作用(光散射等)越強。進而認為，於含氟聚合物所具有之交聯性基為羥基或羧基之情形時，水性分散液之著色穩定性尤其容易降低。然而，本發明中之鹽成分之含量之規定顯著地發揮作為抑制該著色穩定性降低之要因之功能。其結果，認為即便於含氟聚合物之粒子之平均粒徑較小之情形時，本發明之水性分散液之著色穩定性亦優異。 再者，含氟聚合物之平均粒徑係使用ELS-8000(大塚電子股份有限公司製造)藉由動態光散射法求出之D50之值。此處，D50表示於藉由動態光散射法測定之粒子之粒度分佈中，自較小之粒子側起開始計算之體積累計50體積%之粒子直徑。 本發明中之鹽成分係於製造含氟聚合物時用作聚合起始劑之過硫酸鹽之殘存物及/或過硫酸鹽之分解物。若於聚合時聚合起始劑之使用量較多，則水性分散液中之鹽成分之含量變多，若使用量較少，則其含量變少。鹽成分不僅於儲藏時進一步分解等而導致水性分散液之著色，而且亦導致水性分散液之pH值之經時性降低。 本發明中之過硫酸鹽較佳為過硫酸銨鹽、過硫酸鉀鹽、或過硫酸鈉鹽。 水性分散液中之鹽成分之含量相對於含氟聚合物100 g，以過硫酸鹽換算計為0.01～0.22 mmol，較佳為0.01～0.15 mmol，更佳為0.01～0.10 mmol，進而較佳為0.01～0.05 mmol。再者，所謂鹽成分之含量係過硫酸鹽及其分解物之合計含量(亦包括不含過硫酸鹽及其分解物之任一者之情形)。 若鹽成分之含量為上述下限值以上，則迅速進行聚合，單體以較高之反應率進行聚合，因此可高效率地獲得含氟聚合物。 若鹽成分之含量為上述上限值以下，則不僅水性分散液、水性塗料及由水性塗料形成之塗膜(以下亦稱為本塗膜)之著色穩定性優異，而且水性分散液及水性塗料之pH值穩定性變得良好。其結果，水性分散液及水性塗料之觸變性之穩定性變得良好。 進而，由於水性分散液及水性塗料之經時性之著色穩定性變得良好，因此本塗膜之著色穩定性進一步變得良好。又，由於水性塗料之觸變性之穩定性變得良好，因此水性塗料之「易塗佈性、難下垂性」提高，可對物品(被塗裝物)均勻地塗裝，本塗膜之均一性提高。 即，於由水性分散液製備水性塗料時，通常添加增黏劑而將水性塗料之觸變性調整為合適之範圍。由於增黏劑之作用受到水性分散液之pH值之影響，因此若水性分散液之pH值經時性變化，則水性塗料之觸變性亦變化，而自經調整之範圍偏離，塗裝時之均一性降低，但於本發明之水性分散液及水性塗料中，塗裝之均一性不會降低。 本發明之水性分散液之製造方法係上述本發明之水性分散液之製造方法，其係於過硫酸鹽之存在下，在水性介質中使包含單體1及單體2之單體混合物進行聚合。 過硫酸鹽之使用量相對於單體混合物之總量100 g為0.01～0.22 mmol。 單體混合物可視需要進一步含有單體3。 此處，單體1、單體2及單體3之各種類及水性介質之定義如上文所述之本發明之水性分散液中所說明。又，含氟聚合物之較佳態樣亦如本發明之水性分散液中所說明。 例如，單體1、單體2、及視需要使用之單體3可以所製造之含氟聚合物之單元1、單元2及單元3成為所需比率之方式使用。 作為含氟聚合物之較佳之具體例，可列舉單元1之含量(莫耳%)相對於單元2之含量(莫耳%)之比率(單元1之含量/單元2之含量)為0.5～800之含氟聚合物，更佳可列舉為1.5～300之含氟聚合物。 又，於含氟聚合物進而含有單元3之情形時，可列舉單元3之含量相對於單元1與單元2之總含量之比率(單元3之含量/單元1之含量與單元2之含量之和)為0.1～1.5之含氟聚合物。 單體3之莫耳數相對於單體1與單體2之總莫耳數之比率(單體3之莫耳數/(單體1之莫耳數＋單體2之莫耳數))較佳為0.1～1.5。 本發明之製造方法中之過硫酸鹽較佳為過硫酸銨鹽、過硫酸鉀鹽或過硫酸鈉鹽。 過硫酸鹽之使用量相對於單體混合物之總和100 g為0.01～0.22 mmol。又，過硫酸鹽之使用量相對於單體混合物之總和100 g，以過硫酸鹽換算計較佳為0.01～0.15 mmol，更佳為0.01～0.10 mmol，進而較佳為0.01～0.05 mmol。 再者，過硫酸鹽之使用量理論上與鹽成分之含量相等。 若過硫酸鹽之使用量較多，則於所獲得之水性分散液中，鹽成分之含量變多，不僅水性分散液之儲藏時等之著色穩定性受損，而且水性分散液之pH值容易經時性降低。另一方面，若過硫酸鹽之使用量較少，則聚合之進行變慢，單體不會以較高之反應率進行聚合。其結果，無法高效率地獲得含氟聚合物，視情形會完全不進行聚合。若過硫酸鹽之使用量為上述範圍，則所獲得之水性分散液之著色穩定性、pH值穩定性及聚合時之生產性變得更良好。 於本發明之製造方法中，亦可與過硫酸鹽組合而併用其他聚合起始劑。 作為其他聚合起始劑，可列舉：含有過氧化氫與亞硫酸氫鈉等之組合之氧化還原起始劑；將亞鐵鹽、硝酸銀等無機系起始劑混合而成之聚合起始劑；過氧化二琥珀酸、過氧化二戊二酸、偶氮雙丁腈等有機系聚合起始劑等。 併用其他聚合起始劑之情形時之使用量相對於過硫酸鹽，較佳為1～100莫耳%，更佳為5～95莫耳%。 本發明之製造方法中之於水性介質中之聚合較佳為乳化聚合。於乳化聚合中通常使用乳化劑。 乳化劑較佳為非離子性乳化劑或陰離子性乳化劑。 作為非離子性乳化劑，可列舉：烷基苯酚環氧乙烷加成物、高級醇環氧乙烷加成物、環氧乙烷與環氧丙烷之嵌段共聚物等。 作為陰離子性乳化劑，可列舉：烷基苯磺酸鹽、烷基萘磺酸鹽、高級脂肪酸鹽、烷基硫酸酯鹽、烷基醚硫酸酯鹽、磷酸酯鹽等。 乳化劑之使用量根據單體之種類決定即可，於上文所述之巨單體具有如乳化劑之聚合系統之穩定化效果之情形時，亦可不使用乳化劑。 於本發明之製造方法中，可使用鏈轉移劑調節含氟聚合物之聚合度(分子量)。又，亦可提高水性介質中之單體之濃度之合計。 作為鏈轉移劑，可列舉：烷基硫醇(第三-十二烷基硫醇、正十二烷基硫醇、硬脂基硫醇等)、胺基乙硫醇、巰基乙醇、3-巰基丙酸、2-巰基丙酸、硫代蘋果酸、硫代乙醇酸、3,3'-二硫代-二丙酸、硫代乙醇酸2-乙基己酯、硫代乙醇酸正丁酯、硫代乙醇酸甲氧基丁酯、硫代乙醇酸乙酯、2,4-二苯基-4-甲基-1-戊烯、四氯化碳等。 鏈轉移劑之使用量相對於單體混合物，較佳為0～2質量%。 本發明之製造方法之聚合方式並無特別限定，可列舉利用分批聚合法、滴加單體混合物之滴加聚合法、連續聚合法等之方式。 本發明之水性塗料係含有本發明之水性分散液之水性塗料，其含有鹽成分，且鹽成分之含量相對於含氟聚合物100 g，以過硫酸鹽換算計為0.01～0.22 mmol。 本發明之水性塗料通常為藉由水性介質等將上述之本發明之水性分散液進行稀釋，並視需要含有添加劑而獲得。 稀釋所使用之水性介質與本發明之水性分散液中所說明之水性介質相同。 稀釋所使用之水性介質之使用量並無特別限定，較佳為水性塗料中之含氟聚合物之含量相對於水性塗料之總量成為5～60質量%之量，更佳為成為10～50質量%之量。若含氟聚合物之含量為上述下限值，則可獲得耐候性更優異之塗膜，若為上述上限值，則塗膜之透明性更優異。 水性塗料中之鹽成分之含量相對於含氟聚合物100 g，以過硫酸鹽換算計為0.01～0.22 mmol，較佳為0.01～0.15 mmol，更佳為0.01～0.10 mmol，尤佳為0.01～0.05 mmol。若鹽成分之含量為上述之範圍內，則可抑制水性塗料於保管時之著色或水性塗料之pH值之經時性降低。 再者，於向水性分散液中添加各種添加劑等而製備水性塗料之情形時，存在混入鹽成分之情形。例如，於追加含氟聚合物、或添加其他聚合物時，存在混入源自該等聚合物之聚合起始劑之鹽成分之情形。然而，即便於自添加劑等混入鹽成分之情形時，本發明之水性塗料中之鹽成分之含量亦較佳為上述範圍。 本發明之水性塗料亦可於不妨礙本發明之作用效果之範圍內，視需要除了水性分散液及稀釋所使用之水性介質以外，含有含氟聚合物以外之其他聚合物、乳化劑、著色劑、硬化劑、其他添加劑。 例如，可於本發明之水性塗料中含有著色劑。 又，藉由於本發明之水性塗料中含有硬化劑，所獲得之塗膜之耐候性、耐水性、耐化學品性、耐熱性等進一步提高。本發明之水性塗料可為一液型，亦可為二液型，於含有硬化劑之情形時，較佳為製成二液型，於將要使用前將兩液混合。 作為該其他聚合物，並無特別限定，例如可列舉：(甲基)丙烯酸系聚合物、聚酯系樹脂、聚胺基甲酸酯系樹脂、環氧系樹脂、丙烯醯基矽酮系樹脂、三聚氰胺系樹脂、脲系樹脂、乙烯系樹脂、氟系樹脂、酚系樹脂、醇酸系樹脂等。 於含有該其他聚合物之情形時，水性塗料中之其他聚合物之含量較佳為10～60質量%。若將其他聚合物之含量設為上述下限值，則可發揮其他聚合物所具有之特性，另一方面，若為上述上限值，則無損含氟聚合物所具有之特性。 為了提高乳化穩定性，亦可於本發明之水性塗料中添加乳化劑。水性塗料中所含之乳化劑之種類與本發明之水性分散液中所說明之乳化劑相同。 作為著色劑，可列舉染料、有機顏料、無機顏料等。 著色劑之含量相對於水性塗料之總量100，較佳為1～300質量%。 作為硬化劑，例如可列舉：六亞甲基異氰酸酯三聚物等封端異氰酸酯或其乳化分散體；甲基化三聚氰胺、羥甲基化三聚氰胺、羥丁基化三聚氰胺等三聚氰胺樹脂；甲基化脲、丁基化脲等脲樹脂等。 硬化劑之含量係所使用之單體之總量，較佳為10～150莫耳%。 作為其他添加劑，可列舉塑化劑、紫外線吸收劑、調平劑、抗收縮劑、防結皮劑等。 本發明之塗裝物品於物品之表面具有本發明之水性塗料之塗膜。 本發明之塗裝物品可藉由於物品之表面塗佈本發明之水性塗料並加以乾燥形成塗膜而製造。 作為物品，並無特別限制，可列舉：金屬板、木板、塑膠板、玻璃板、瀝青、混凝土等。 作為塗佈方法，可列舉使用毛刷、輥、浸漬、噴霧器、輥塗機、模嘴塗佈機、敷料器、或旋轉塗佈機等塗裝裝置進行之方法。 塗膜之厚度較佳為5～50 μm。若塗膜之厚度為上述下限值，則可獲得視認性、設計性較高之螢光塗膜，若為上述上限值，則塗膜之表層與內部之硬化程度不存在差異，可獲得均勻之塗膜。 塗佈後之乾燥溫度較佳為25～300℃左右。 根據本發明之水性分散液之製造方法，由於聚合時所使用之過硫酸鹽之使用量較少，因此可製造鹽成分之含量較少之本發明之水性分散液。 本發明之水性分散液由於鹽成分之含量較少，因此著色穩定性、pH值穩定性優異。如上文所述，於由水性分散液製備水性塗料時，多數情況下藉由添加增黏劑等而以成為作為塗料所最佳之黏度之方式調整黏度。已知水性塗料之黏度根據水性分散液之pH值而變化，若其pH值經時性變化，則即便於製備水性塗料時將黏度調整為最佳，隨著pH值之變化，黏度亦會經時性地變化，水性塗料之使用時之黏度偏離最佳值。本發明之水性分散液由於pH值穩定性優異，因此於製成水性塗料之情形時，黏度之變化較少，觸變性優異。 又，本發明之水性塗料由於觸變性之穩定性優異，塗料之黏度得以保持為最佳之範圍，因此可對物品均勻地塗裝。 因此，本發明之水性塗料及使用其而形成之塗膜之著色穩定性、均一性亦優異。 又，由自含有具有單元1及單元2之含氟聚合物之本發明之水性分散液製備的本發明之水性塗料形成之塗膜之耐候性、耐水性、耐化學品性、耐熱性等優異。 實施例 藉由以下之實施例對本發明進行具體說明，但本發明並不限定於本實施例。 將下文所述之各例所使用之測定方法示於以下。 ＜測定方法＞ [過硫酸鹽量之算出] (添加有水性分散液之硫酸銨鐵(II)之滴定) 將水性分散液W(g)溶解於離子交換水10 g中，以其作為試樣溶液。 於試樣溶液中添加90 g/L硫酸銨鐵(II)水溶液20 mL及磷酸20 mL，獲得混合液。於該混合液中滴加0.02 mol/L過錳酸鉀水溶液直至溶液呈微紅色為止。將此時之滴定量設為A(mL)。 (硫酸銨鐵(II)之滴定) 於離子交換水10 g中添加90 g/L硫酸銨鐵(II)水溶液20 mL及磷酸20 mL，獲得混合液。於該混合液中滴加0.02 mol/L過錳酸鉀水溶液直至溶液呈微紅色為止。將此時之滴定量設為B(mL)。 (過硫酸鹽量之算出方法) 首先，藉由下式(1)算出水性分散液中之過硫酸鹽之濃度C(質量%)。再者，水性塗料中之過硫酸鹽之濃度亦可以同樣之方式算出。 C＝{(B－A)×f×Mw×0.00005/W}×100 (1) f：表示0.02 mol/L過錳酸鉀水溶液之濃度之程度，為對該過錳酸鉀水溶液中所含之過錳酸鉀量進行修正之值。 Mw：過硫酸鹽之分子量。 此處，上述之滴定係如下所述之方法：預先使試樣溶液中之過硫酸鹽與硫酸銨鐵(II)進行氧化還原反應，以過錳酸鉀對過量之硫酸銨鐵(II)進行反滴定而測定過硫酸鹽量。 硫酸銨鐵(II)與過錳酸鉀之氧化還原反應如下式(61)所示。 5FeSO4
(NH4
)2
SO4
＋KMnO4
→5Fe3+
＋10SO4 2-
＋10NH4 +
＋K+
＋MnO4 6-
(61) 硫酸銨鐵(II)與過硫酸鹽之氧化還原反應如下式(62)所示。 2FeSO4
(NH4
)2
SO4
＋QS2
O8
→2Fe3+
＋4SO4 2-
＋4NH4 +
＋2SO4 2-
＋Q (62) Q：胺類、鹼金屬類等之抗衡陽離子。 根據上述滴定之結果即滴定量A、滴定量B、及式(61)、式(62)導出下式(63)。 C＝{(B－A)/1000×0.02×f×5/2×Mw/W}×100 (63) 藉由計算式(63)之常數可導出式(6)。 f之具體之數值可藉由使用體積分析用「標準物質」進行之標定法(以下稱為直接法)、或使用已藉由直接法確定因數之體積分析用「標準液」進行之標定法(稱為間接法)而求出，於本測定中為1.003。 繼而，藉由下式(7)，算出水性分散液中每100 g含氟聚合物固形物成分之殘存過硫酸鹽之量Y(mmol)。 Y＝(C/X)×100/Mw (7) X：水性分散液中之含氟聚合物固形物成分濃度(質量%)。 [硫酸根離子量之算出] 藉由以下程序算出作為過硫酸鹽之分解物之硫酸根離子之量。再者，水性塗料中之硫酸根離子之量亦可以同樣之方式算出。 將藉由超純水將所製造之水性分散液稀釋1000倍而成之試樣溶液裝入至超過濾器中，使用半徑13 cm之轉子(Kokusan公司製造之「H-18」)，於4000 rpm之條件下離心分離60分鐘。藉由超純水將濾液稀釋10倍，獲得試樣稀釋液。 繼而，使用離子層析系統(Nippon Dionex股份有限公司製造，ICS-3000)，對該稀釋液中之硫酸根離子濃度I(μg/mL)進行測定。 根據該結果，藉由下式(8)算出水性分散液中每100 g含氟聚合物固形物成分之硫酸根離子量(過硫酸鹽換算)Z(mmol)。再者，式中之96為硫酸根離子之分子量。 Z＝10×I/(d×X×96) (8) d：水性分散液之比重。 X：水性分散液中之含氟聚合物固形物成分濃度(質量%)。 [色度(YI(yellowness index，黃色指數)值)之測定] 分別藉由離子交換水將實施例1～6及比較例1中獲得之水性分散液(剛製造後)稀釋成10倍而製成稀釋試樣。將稀釋試樣裝入至圓筒單元(30f
×30 mm)中，藉由測色色差計(日本電色工業股份有限公司製造，ZE-2000)測定YI值。 又，將實施例1～6及比較例1中獲得之水性分散液於50℃下保存2週，對於保存後之水性分散液亦以與上述同樣之方式測定YI值。 YI值越低，表示越未著色。 [pH值之測定] 測定實施例1～6及比較例1中獲得之水性分散液(剛製造後)於25℃下之pH值。 又，將實施例1～6及比較例1中獲得之水性分散液於50℃下保存2週，對於保存後之水性分散液亦測定於25℃下之pH值。 [觸變性之穩定性之評價] 將實施例1～6及比較例1之水性分散液分別與造膜助劑TEXANOL(Eastman Chemical公司製造)、消泡劑Dehydran 1620(San Nopco公司製造)、鹼膨潤型增黏劑TT-615(Rohm & Haas公司製造)及氨水進行調配而製備水性塗料。各材料之調配量係將水性塗料之黏度以觸變性成為作為水性塗料所適當之範圍之方式調整。 將所獲得之水性塗料於50℃下保存2週，根據保存前、保存後之各水性塗料之觸變性，按照以下基準對觸變性之穩定性進行評價。 ○：保存未導致觸變性降低。 △：保存導致觸變性略有降低。 ×：保存導致觸變性明顯降低。 水性塗料之觸變性：依照JIS K 5600-2-3所規定之錐-板黏度計法，使用No.4之轉子，於25℃下測定轉數5 rpm時、轉數50 rpm時之各水性塗料之黏度，算出該等黏度之比即TI值(＝轉數5 rpm時之黏度[mPa・s]/轉數50 rpm時之黏度[mPa・s])，以其作為觸變性之指標。 ＜實施例1＞ 於容器積250 mL之附不鏽鋼製攪拌機之高壓釜中裝入環己基乙烯基醚(以下稱為CHVE)34 g、2-乙基己基乙烯基醚(以下稱為2EHVE)19 g、環己烷二甲醇單乙烯醚(以下稱為CHMVE)2.8 g、1-乙烯氧基甲基-4-(聚氧伸乙基)環己基甲基醚(以下稱為CMEOVE)1.7 g、離子交換水93 g、碳酸鉀0.26 g、過硫酸銨(以下稱為APS)0.012 g、非離子性乳化劑(DKS NL-100：第一工業製藥股份有限公司製造)5.2 g、陰離子性乳化劑(月桂基硫酸鈉；以下稱為SLS)0.1 g，藉由冰進行冷卻，以成為0.5 MPa之方式進行氮氣加壓而進行脫氣。將該加壓脫氣重複進行2次後，脫氣至-0.8 MPa而將溶存空氣去除後，壓入CF2
=CFCl(以下稱為CTFE)47 g，於50℃下進行36小時之聚合反應。聚合反應後，藉由200目之尼龍布將水性分散液過濾。繼而，使用離子交換水，以固形物成分濃度成為52質量%之方式進行調整，獲得含有粒子狀之含氟聚合物之水性分散液。含氟聚合物之粒子之平均粒徑為150 nm。 再者，上述CMEOVE係CHMVE之環氧乙烷加成物，每分子之氧伸乙基數量平均約為15。 ＜實施例2～4及比較例1＞ 於實施例2～4及比較例1中，將APS之使用量以表1所示之方式進行變更，除此以外，以與實施例1同樣之方式獲得水性分散液。各例中之含氟聚合物之平均粒徑均為140～160 nm之範圍內。 ＜實施例5＞ 於容器積250 mL之附不鏽鋼製攪拌機之高壓釜中裝入1.4 g之CHVE、37 g之乙基乙烯基醚(以下稱為EVE)、3.8 g之CHMVE、3.1 g之CMEOVE、97 g之離子交換水、0.26 g之碳酸鉀、0.0025 g之APS、5.5 g之非離子性乳化劑(DKS NL-100：第一工業製藥股份有限公司製造)、0.1 g之SLS，藉由冰進行冷卻，以成為0.5 MPa之方式進行氮氣加壓而進行脫氣。將該加壓脫氣重複進行2次後，脫氣至-0.8 MPa而將溶存空氣去除後，壓入64 g之CTFE，於50℃下進行36小時之聚合反應。聚合反應後，藉由200目之尼龍布將水性分散液過濾。繼而，使用離子交換水，以固形物成分濃度成為52質量%之方式進行調整，獲得水性分散液。 ＜實施例6＞ 將非離子性乳化劑(DKS NL-100：第一工業製藥股份有限公司製造)之添加量變為2.6 g，除此以外，以與實施例3同樣之方式獲得含有粒子狀之含氟聚合物之水性分散液。含氟聚合物之粒子之平均粒徑為210 nm。 對於各水性分散液，算出乳膠產率、過硫酸鹽量及硫酸根離子量。乳膠產率表示相對於原料中離子交換水以外之原料總量之比率的聚合反應後液中之固形物成分量之比率(質量%)(以下相同)。鹽成分之含量(過硫酸鹽換算)係累加過硫酸鹽量及硫酸根離子量而求出。又，對於所獲得之水性分散液，測定色度(YI值)及pH值，並評價觸變性之穩定性。 將各例中之原料之使用量、相對於含氟聚合物100 g之鹽成分之含量(過硫酸鹽(APS)及其分解物之合計含量(過硫酸鹽換算))之算出結果、YI值及pH值之測定結果、以及觸變性之穩定性之評價結果示於表1。又，關於YI值、pH值，將剛製造後之值與在50℃下保存2週後之值之差的絕對值示於表1。 [表1]
於水性分散液中之相對於含氟聚合物100 g之過硫酸鹽(APS)及其分解物之合計含量(過硫酸鹽換算)為0.24 mmol之比較例1中，剛製造後之YI值為-5.8，於50℃下保存2週後之YI值為1.4，其變化幅度為7.2。 相對於此，於該合計含量(過硫酸鹽換算)為0.22 mmol以下之實施例1～4中，剛製造後之YI值為-6.4以下，於50℃下保存2週後之YI值之變化幅度為-0.7以下，低於比較例1，著色受到抑制。又，保存前後之YI值之變化幅度亦較少。於實施例1～4中，亦係水性分散液中之相對於含氟聚合物100 g之合計含量(過硫酸鹽換算)越低之實施例的YI值越低，保存前後之YI值之變化越小。 於一部分單體之種類及調配量不同之實施例5中，水性分散液中之相對於含氟聚合物100 g之合計含量(過硫酸鹽換算)為0.01 mmol。實施例5之剛製造後之YI值為-11，於50℃下保存2週後之YI值為-9.7，亦低於比較例1。又，保存前後之YI值之變化亦較少。 又，根據含氟聚合物之粒子之平均粒徑為200 nm以下之實施例3與含氟聚合物之粒子之平均粒徑為200 nm以上之實施例6之對比可知，若平均粒徑為200 nm以下，則剛製造後之YI值、於50℃下保存2週後之YI值、保存前後之YI值之變化幅度均較小，著色受到抑制。 於實施例1～6中，剛製造後之pH值與在50℃下保存2週後之pH值之差小於比較例1。 使用實施例1～6之水性分散液之水性塗料與使用比較例1之水性塗料相比，於50℃下保存2週時之觸變性之降低較少。 再者，於除了將實施例5中之過硫酸鹽(APS)量設為半量(0.005 mmol)以外，以同樣之方式製造含有含氟聚合物之水性分散液之情形時，乳膠產率未達90%，未效率良好地獲得含氟聚合物。 [產業上之可利用性] 含有本發明之水性分散液之水性塗料例如可用於建築等所使用之木材、裝置等所使用之金屬等之塗裝。 再者，將於2016年01月14日提出申請之日本專利申請案2016-005299號之說明書、申請專利之範圍及摘要之全部內容引用至此，作為本發明之說明書之揭示而併入。In the present specification, the "unit based on a monomer" is a general term for an atomic group directly formed by polymerization of one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group. In addition, hereinafter, a unit based on a single unit is also simply referred to as a "unit". The content (mol%) of each unit of the fluoropolymer can be determined by analyzing the fluoropolymer by nuclear magnetic resonance spectroscopy, or can be estimated from the amount of each monomer added. The "crosslinkable group" means a group which can form a crosslinked structure by reacting with a curing agent to form a crosslinked structure or a crosslinkable group. The term "hardener" means a compound having two or more groups reactive with a "crosslinkable group" and capable of forming a crosslinked structure by reacting with a crosslinkable group. The "(meth) acrylate" is a generic term for acrylate and methacrylate. The aqueous dispersion of the present invention has a fluoroolefin-based unit and a fluoropolymer based on a unit having a crosslinkable group, and is dispersed in an aqueous medium, which is selected from the group consisting of persulfate and its decomposition product. At least one component of the group (hereinafter also referred to as "salt component"), and the content of the salt component is 0.01 to 0.22 mmol in terms of persulfate relative to 100 g of the fluoropolymer. The aqueous dispersion of the present invention is an aqueous dispersion obtained by a polymerization method described in the method for producing an aqueous dispersion described below. Therefore, the aqueous dispersion of the present invention contains at least an aqueous medium, a fluoropolymer and a salt component, and may contain components used in the polymerization in addition to these. Examples of the component to be used in the polymerization include an emulsifier, a chain transfer agent, and the like described in the method for producing an aqueous dispersion described below. As the aqueous medium in the present invention, it is water or a mixture of water and a water-soluble organic solvent. Examples of the water-soluble organic solvent include third butanol, propylene glycol, dipropylene glycol, dipropylene glycol monomethyl ether, and tripropylene glycol. When the aqueous medium contains a water-soluble organic solvent, the dispersibility of the monomer in the aqueous medium during polymerization and the dispersibility of the fluoropolymer produced are improved, and productivity is improved. The content of the water-soluble organic solvent is preferably from 1 to 40 parts by mass, more preferably from 3 to 30 parts by mass, per 100 parts by mass of the water. The fluoropolymer in the present invention has a unit based on a fluoroolefin (hereinafter also referred to as "monomer 1") (hereinafter also referred to as "unit 1") and a monomer based on a crosslinkable group (hereinafter also referred to as The unit of "monomer 2") (hereinafter also referred to as "unit 2"). The fluoropolymer may further have a unit (hereinafter also referred to as "unit 3") based on a monomer other than the monomer 1 and the monomer 2 (hereinafter also referred to as "monomer 3"). The content of the fluoropolymer in the aqueous dispersion is preferably from 10 to 70% by mass, particularly preferably from 20 to 60% by mass, based on the total mass of the aqueous dispersion. When the content of the fluoropolymer is at least the above lower limit value, the polymerization is rapidly carried out, and a high reaction rate can be obtained. On the other hand, when it is at most the upper limit, the dispersion stability of the fluoropolymer in the aqueous dispersion and the color stability thereof are further improved. In the present invention, a compound in which one or more hydrogen atoms of a monomer 1 olefin are substituted with a fluorine atom. In the monomer 1, one or more hydrogen atoms which are not substituted with a fluorine atom may be substituted with a chlorine atom. As monomer 1, preferably CF2
=CF2
, CF2
=CFCl, CF2
=CHF, CH2
=CF2
, CF2
=CFCF3
And CF2
=CHCF3
, in terms of the weather resistance of the obtained coating film, it is more preferably CF2
=CF2
And CF2
=CFCl, especially CF2
=CFCl. The monomer 1 may be used in combination of two or more. The crosslinkable group of the monomer 2 in the present invention is preferably a hydroxyl group, a hydrolyzable alkylene group, a carboxyl group, an amine group, an isocyanato group, an epoxy group or an oxetanyl group, and particularly preferably a hydroxyl group or a carboxyl group. The monomer 2 (a monomer having a hydroxyl group) having a crosslinkable group of a hydroxyl group may, for example, be a hydroxyalkyl vinyl ether (hydroxyethyl vinyl ether or hydroxybutyl vinyl ether), having a hydroxyl group and a vinyloxy group. a cycloalkane (cyclohexanedimethanol monovinyl ether, etc.), ethylene glycol monovinyl ether (diethylene glycol monovinyl ether, triethylene glycol monovinyl ether, tetraethylene glycol monovinyl ether, etc.), hydroxyl group An alkyl allyl ether (hydroxyethyl allyl ether, hydroxybutyl allyl ether, etc.), a cycloalkane having a hydroxyl group and an allyloxy group (cyclohexane dimethanol monoallyl ether, etc.), a hydroxy alkane Vinyl ester (vinyl hydroxyethyl carboxylate, vinyl hydroxybutyl carboxylate, etc.), cycloalkane having a hydroxyl group and a vinyloxycarbonyl group (((hydroxymethylcyclohexyl)methoxy) vinyl acetate, etc.) , allyl hydroxyalkylcarboxylate (allyl hydroxyethylcarboxylate, allyl hydroxybutylcarboxylate, etc.), cycloalkane having a hydroxyl group and an allyloxycarbonyl group (((hydroxymethylcyclohexyl) a methoxyalkyl (meth) acrylate (such as hydroxyethyl (meth) acrylate). As the monomer having a hydroxyl group, a hydroxyalkyl vinyl ether and a hydroxyalkyl allyl ether are preferable, and a hydroxyalkyl vinyl ether is particularly preferable. The monomer 2 (monomer having a carboxyl group) having a carboxyl group as a crosslinkable group may, for example, be an unsaturated monocarboxylic acid (3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid or 3-hexene). Acid, 5-hexenoic acid, 2-heptenoic acid, 3-heptenoic acid, 6-heptenoic acid, 3-octenoic acid, 7-octenoic acid, 2-decenoic acid, 3-decenoic acid, 8-decenoic acid, 9-decenoic acid, 10-undecenoic acid, acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, etc.), saturated monocarboxylic acid vinyl ether (ethylene oxyvaleric acid, 3- Ethoxypropionic acid, 3-(2-vinyloxybutoxycarbonyl)propionic acid, 3-(2-vinyloxyethoxycarbonyl)propionic acid, etc., saturated monocarboxylic acid allyl ether (ene) Propoxy valeric acid, 3-allyloxypropionic acid, 3-(2-allyloxybutoxycarbonyl)propionic acid, 3-(2-allyloxyethoxycarbonyl)propionic acid, etc.) , saturated polycarboxylic acid monovinyl ester (adethylene adipate monovinyl ester, succinic acid monovinyl ester, vinyl phthalate, pyromellitic acid, etc.), unsaturated dicarboxylic acid or its intramolecular acid anhydride (I Butic acid, maleic acid, fumaric acid, maleic anhydride, itaconic anhydride, etc.), unsaturated carboxylic acid monoester (Icon acid monoester, butene Diacid monoester, fumaric acid monoester, etc.). As the monomer having a carboxyl group, an unsaturated monocarboxylic acid is preferred, and 10-undecenoic acid and crotonic acid are preferred. The monomer 2 (a monomer having a hydrolyzable alkylene group) having a crosslinkable group which is a hydrolyzable alkylene group is exemplified by (CH)2
=CHC(O)O(CH2
)3
Si(OCH3
)3
, CH2
=CHC(O)O(CH2
)3
Si (OC2
H5
)3
, CH2
=C(CH3
)C(O)O(CH)2
)3
Si(OCH3
)3
, CH2
=C(CH3
)C(O)O(CH)2
)3
Si (OC2
H5
)3
, CH2
=CHC(O)O(CH2
)3
SiCH3
(OC2
H5
)2
, CH2
=C(CH3
)C(O)O(CH)2
)3
SiC2
H5
(OCH3
)2
, CH2
=C(CH3
)C(O)O(CH)2
)3
Si(CH3
)2
(OC2
H5
), CH2
=C(CH3
)C(O)O(CH)2
)3
Si(CH3
)2
OH, CH2
=CHC(O)O(CH2
)3
Si(OCOCH3
)3
, CH2
=C(CH3
)C(O)O(CH)2
)3
SiC2
H5
(OCOCH3
)2
, CH2
=C(CH3
)C(O)O(CH)2
)3
SiCH3
(N(CH)3
)COCH3
)2
, CH2
=CHC(O)O(CH2
)3
SiCH3
[ON(CH3
)C2
H5
]2
, CH2
=C(CH3
)C(O)O(CH)2
)3
SiC6
H5
[ON(CH3
)C2
H5
]2
(meth) acrylate having a hydrolyzable decyl group; CH2
=CHSi[ON=C(CH3
) (C2
H5
)]3
, CH2
=CHSi(OCH3
)3
, CH2
=CHSi(OC2
H5
)3
, CH2
=CHSiCH3
(OCH3
)2
, CH2
=CHSi(OCOCH3
)3
, CH2
=CHSi(CH3
)2
(OC2
H5
), CH2
=CHSi(CH3
)2
SiCH3
(OCH3
)2
, CH2
=CHSiC2
H5
(OCOCH3
)2
, CH2
=CHSiCH3
[ON(CH3
)C2
H5
]2
, CH2
=CHSiCl3
Vinyl decane; vinyl ether having a hydrolyzable decyl group. The monomer having a hydrolyzable alkylene group may also be a partially hydrolyzed condensate. The monomer 2 (monomer having an amine group) having an amine group as a crosslinking group may, for example, be an aminoalkyl vinyl ether, an aminoalkyl vinyl ester, an aminomethyl styrene, or a vinylamine. Acrylamide, vinyl acetamide, vinyl formamide, and the like. The monomer 2 (the monomer having an isocyanate group) having an isocyanate group as a crosslinkable group may, for example, be 2-isocyanatoethyl methacrylate or 2-isocyanatoethyl acrylate. 2-isocyanatoethyl ethoxy methacrylate, 2-isocyanatoethyl vinyl ether, and the like. Examples of the monomer 2 (the monomer having an epoxy group) in which the crosslinkable group is an epoxy group include glycidyl vinyl ether, glycidyl methacrylate, and 3,4-epoxy ring of methacrylic acid. Hexylmethyl ester, 3,4-epoxycyclohexylmethyl vinyl ether, 4-vinyloxymethylcyclohexyl glycidyl ether, and the like. A preferred example of the other monomer 2 is a monomer having a crosslinkable group and a hydrophilic moiety (hereinafter also referred to as "macromonomer"). The hydrophilic portion means a portion having a hydrophilic group or a portion having a hydrophilic bond, or a portion including a combination of the portions. The hydrophilic group may be any of ionic, nonionic, and amphoteric. In terms of chemical stability of the aqueous dispersion, it is preferred to combine a site having a nonionic or amphoteric hydrophilic group with a site having another hydrophilic group, or a combination having a hydrophilic group and having hydrophilicity. The part of the key. Specific examples of the macromonomer include J-Q-[O-Y-]n
-OR represented by the compound, J-Q-O(C(O)-Z-O-)m
a compound represented by R or the like (wherein, in the formula, J represents a vinyloxy group or an allyloxy group, and Q represents an alkylene group having 1 to 10 carbon atoms or an alkylene group having a ring structure having a carbon number of 6 to 10, Y represents an alkylene group having 1 to 4 carbon atoms, R represents a hydrogen atom, n represents an integer of 2 to 20, Z represents an alkylene group having 1 to 10 carbon atoms, and m represents an integer of 1 to 30; the same applies hereinafter. The group represented by -[O-Y-]- is preferably an oxygen-extended ethyl group (i.e., Y is a dimethylene group). Also, -[O-Y-]n
- the hydrophilic moiety represented may contain two or more groups represented by -[O-Y-]- (for example, -OCH2
CH2
- with -OCH2
CH(CH3
)-). Each of the groups in the case of containing two or more kinds of groups may be arranged in any of a block type or a random type. As a macromonomer, it is preferably J-Q-[O-Y-]n
a compound represented by -OH (wherein, J, Q, and n are as defined above; and Y is an alkylene group having 2 to 4 carbon atoms (wherein at least a part of n of Y is a dimethylene group)). In the case where Y is an alkylene group other than a methylene group, it is preferably -CH.2
CH(CH3
)-. Preferably, 50% or more of n Y is a dimethylene group, and more preferably 80 to 100% is a dimethylene group. Further, the macromonomer may be a chain obtained by radically polymerizing a hydrophilic ethylenically unsaturated monomer, and having a radically polymerizable unsaturated group such as a vinyloxy group or an allyloxy group at a single terminal. body. The macromonomer can be produced by the method described in Polym. Bull., 5.335 (1981). That is, in the presence of a polymerization initiator having a condensable functional group and a chain transfer agent, a hydrophilic group-containing ethylenically unsaturated monomer is subjected to radical polymerization to produce a polymer having a condensable functional group. Things. Then, the functional group of the polymer is reacted with a compound such as glycidyl vinyl ether or glycidyl allyl ether, and a radical polymerizable unsaturated group is introduced into the terminal. Examples of the ethylenically unsaturated monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, and 2-methoxy (meth) acrylate. Ethyl ethyl ester, diacetone acrylamide, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate and vinyl pyrrolidone. The monomer 2 may be used in combination of two or more. The monomer 3 in the present invention is not particularly limited, and examples thereof include an olefin (ethylene, propylene, etc.), an alkyl vinyl ether (ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, 2-B). Cyclohexyl vinyl ether, etc.), cycloalkyl vinyl ether (cyclohexyl vinyl ether, etc.), alkyl vinyl ester (vinyl butyrate, vinyl octanoate, vinyl pivalate, etc.), alkyl olefin Base esters (allyl butyrate, allyl octanoate, allyl pivalate, etc.), aromatic ethylene (styrene, vinyl toluene, etc.), allyl ether (ethyl allyl ether, etc.), (Meth) acrylate (methyl (meth) acrylate, butyl (meth) acrylate, etc.). As the monomer 3, an alkyl vinyl ether, a cycloalkyl vinyl ether, and an alkyl vinyl ester are preferable. Further, as the other monomer 3, J-Q-[O-Y-] as described above can be cited.n
a compound represented by -OR, or J-Q-O (C(O)-Z-O)m
A compound represented by R and a compound in which R is substituted with an alkyl group having 1 to 3 carbon atoms. The fluoropolymer in the present invention preferably has a CF-based2
=CF2
Or CF2
=CFCl unit as unit 1, with hydroxyalkyl vinyl ether or CH based2
=CHO-Q-[O-Y-]n
a unit of a compound represented by -OH as a polymer of unit 2, or having a CF-based2
=CF2
Or CF2
=CFCl unit as unit 1, with hydroxyalkyl vinyl ester based or CH2
=CHCH2
O-Q-[O-Y-]n
The unit of the compound represented by -OH is used as the polymer of the unit 2. In the fluoropolymer of the present invention, the ratio of the content of the unit 1 (% by mole) to the content of the unit 2 (% by mole) (the content of the unit 1 / the content of the unit 2) is preferably from 0.5 to 800. More preferably, it is 1.5 to 300. When the ratio is in this range, not only the dispersibility in the aqueous dispersion is further improved, but also the weather resistance and water resistance of the obtained coating film are further improved. In the case where the fluoropolymer in the present invention further contains the unit 3, the ratio of the content of the unit 3 to the total content of the unit 1 and the unit 2 (the content of the unit 3 / the content of the unit 1 and the content of the unit 2) It is preferably from 0.1 to 1.5. The content of the unit 1 in the fluoropolymer is preferably from 30 to 70 mol%, more preferably from 35 to 65 mol%, still more preferably from 40 to 60 mol, based on all units of the fluoropolymer. ear%. The content of the unit 2 in the fluoropolymer is preferably from 0.5 to 30 mol%, more preferably from 1.0 to 20 mol%, still more preferably from 1.5 to 15 mol, based on all units of the fluoropolymer. ear%. The content of the unit 3 in the fluoropolymer is preferably from 20 to 70 mol%, more preferably from 25 to 65 mol%, still more preferably from 30 to 60 mol, based on all units of the fluoropolymer. ear%. Preferred examples of the fluoropolymer in the present invention include units 2 and 20 having 29.5 to 70 mol% of the unit 1, 0.5 to 30 mol%, based on the total amount of all the units of the polymer. ～70 mol% of the polymer of the unit 3, as a more preferable specific example, the unit having 34 to 65 mol%, the unit 2 of 1.0 to 20 mol%, and the unit 3 of 25 to 65 mol% The polymer. In the aqueous dispersion of the present invention, the fluoropolymer is preferably dispersed in an aqueous medium in the form of particles. The average particle diameter of the fluoropolymer dispersed in the form of particles is preferably 200 nm or less, and particularly preferably 180 nm or less. The lower limit is usually 50 nm. When the average particle diameter is 200 nm or less, the effect of the color stability of the aqueous dispersion becomes remarkable. The reason for this is not necessarily clear, but it is considered as follows. It is considered that the smaller the average particle diameter of the particles of the fluoropolymer dispersed in the aqueous dispersion, the stronger the interaction (light scattering, etc.) between the particles of the fluoropolymer and the colored components derived from the salt component. Further, it is considered that when the crosslinkable group of the fluoropolymer is a hydroxyl group or a carboxyl group, the color stability of the aqueous dispersion is particularly likely to be lowered. However, the specification of the content of the salt component in the present invention remarkably functions as a factor for suppressing the decrease in the coloring stability. As a result, it is considered that the color dispersion stability of the aqueous dispersion of the present invention is excellent even when the average particle diameter of the particles of the fluoropolymer is small. In addition, the average particle diameter of the fluoropolymer is a value of D50 obtained by a dynamic light scattering method using ELS-8000 (manufactured by Otsuka Electronics Co., Ltd.). Here, D50 is a particle diameter of 50% by volume of the volume calculated from the smaller particle side in the particle size distribution of the particles measured by the dynamic light scattering method. The salt component in the present invention is a persulfate residue and/or a persulfate decomposition product used as a polymerization initiator in the production of a fluoropolymer. When the amount of the polymerization initiator used is large during the polymerization, the content of the salt component in the aqueous dispersion increases, and when the amount is small, the content thereof decreases. The salt component causes not only coloration of the aqueous dispersion due to further decomposition or the like during storage, but also causes a decrease in the pH of the aqueous dispersion. The persulfate salt in the present invention is preferably an ammonium persulfate salt, a potassium persulfate salt or a sodium persulfate salt. The content of the salt component in the aqueous dispersion is from 0.01 to 0.22 mmol, preferably from 0.01 to 0.15 mmol, more preferably from 0.01 to 0.10 mmol, more preferably from 0.01 to 0.10 mmol, more preferably from 100 g of the fluoropolymer. 0.01 to 0.05 mmol. Further, the content of the salt component is the total content of the persulfate and its decomposition product (including the case where either the persulfate or the decomposition product thereof is not included). When the content of the salt component is at least the above lower limit value, the polymerization is rapidly carried out, and the monomer is polymerized at a high reaction rate, so that the fluoropolymer can be obtained efficiently. When the content of the salt component is at most the above upper limit value, not only the aqueous dispersion, the aqueous coating material, and the coating film formed of the aqueous coating material (hereinafter also referred to as the coating film) are excellent in color stability, and the aqueous dispersion and the aqueous coating material are also excellent. The pH stability becomes good. As a result, the stability of the thixotropy of the aqueous dispersion and the aqueous coating becomes good. Further, since the color stability of the aqueous dispersion liquid and the aqueous coating material is improved over time, the color stability of the coating film is further improved. In addition, since the stability of the thixotropy of the water-based paint is improved, the "coatability and sagability" of the water-based paint are improved, and the article (the article to be coated) can be uniformly coated, and the coat film is uniform. Sexual improvement. That is, when an aqueous coating material is prepared from an aqueous dispersion, a tackifier is usually added to adjust the thixotropy of the aqueous coating to a suitable range. Since the effect of the tackifier is affected by the pH of the aqueous dispersion, if the pH of the aqueous dispersion changes over time, the thixotropy of the aqueous coating also changes, and the range of the adjustment is deviated from the time of coating. The uniformity is lowered, but in the aqueous dispersions and aqueous coatings of the present invention, the uniformity of coating does not decrease. The method for producing an aqueous dispersion of the present invention is the method for producing an aqueous dispersion of the present invention, which comprises polymerizing a monomer mixture comprising monomer 1 and monomer 2 in an aqueous medium in the presence of a persulfate . The persulfate is used in an amount of 0.01 to 0.22 mmol based on 100 g of the total amount of the monomer mixture. The monomer mixture may further contain monomer 3 as needed. Here, the definitions of the monomers 1, the monomers 2, and the monomers 3 and the aqueous medium are as described above in the aqueous dispersion of the present invention. Further, preferred aspects of the fluoropolymer are also as described in the aqueous dispersion of the present invention. For example, monomer 1, monomer 2, and monomer 3 as needed may be used in such a manner that unit 1, unit 2, and unit 3 of the fluoropolymer produced are in a desired ratio. As a preferable specific example of the fluoropolymer, the ratio of the content of the unit 1 (% by mole) to the content of the unit 2 (% by mole) (the content of the unit 1 / the content of the unit 2) is 0.5 to 800. The fluoropolymer is more preferably a fluoropolymer of 1.5 to 300. Further, in the case where the fluoropolymer further contains the unit 3, the ratio of the content of the unit 3 to the total content of the unit 1 and the unit 2 (the content of the unit 3 / the content of the unit 1 and the content of the unit 2) ) is a fluoropolymer of 0.1 to 1.5. The ratio of the number of moles of monomer 3 to the total number of moles of monomer 1 and monomer 2 (the number of moles of monomer 3 / (the number of moles of monomer 1 + the number of moles of monomer 2)) It is preferably from 0.1 to 1.5. The persulfate in the production method of the present invention is preferably an ammonium persulfate salt, a potassium persulfate salt or a sodium persulfate salt. The persulfate is used in an amount of 0.01 to 0.22 mmol based on 100 g of the total of the monomer mixture. Further, the amount of persulfate used is preferably from 0.01 to 0.15 mmol, more preferably from 0.01 to 0.10 mmol, still more preferably from 0.01 to 0.05 mmol, in terms of persulfate, relative to 100 g of the total of the monomer mixture. Further, the amount of persulfate used is theoretically equal to the content of the salt component. When the amount of persulfate used is large, the content of the salt component is increased in the obtained aqueous dispersion, and the color stability of the aqueous dispersion is not only impaired, but also the pH of the aqueous dispersion is easy. Reduced by time. On the other hand, if the amount of persulfate used is small, the progress of polymerization becomes slow, and the monomer does not undergo polymerization at a high reaction rate. As a result, the fluoropolymer cannot be obtained efficiently, and polymerization is not carried out at all. When the amount of the persulfate used is in the above range, the color stability, pH stability, and productivity at the time of polymerization of the obtained aqueous dispersion are further improved. In the production method of the present invention, other polymerization initiators may be used in combination with the persulfate. Examples of the other polymerization initiator include a redox initiator containing a combination of hydrogen peroxide and sodium hydrogen sulfite; and a polymerization initiator obtained by mixing an inorganic initiator such as a ferrous salt or silver nitrate; An organic polymerization initiator such as persuccinic acid peroxide, diglutaric acid peroxide or azobisbutyronitrile. In the case where other polymerization initiators are used in combination, the amount used is preferably from 1 to 100 mol%, more preferably from 5 to 95 mol%, based on the persulfate. The polymerization in the aqueous medium in the production method of the present invention is preferably emulsion polymerization. Emulsifiers are commonly used in emulsion polymerization. The emulsifier is preferably a nonionic emulsifier or an anionic emulsifier. Examples of the nonionic emulsifier include an alkylphenol ethylene oxide adduct, a higher alcohol ethylene oxide adduct, and a block copolymer of ethylene oxide and propylene oxide. Examples of the anionic emulsifier include an alkylbenzenesulfonate, an alkylnaphthalenesulfonate, a higher fatty acid salt, an alkyl sulfate salt, an alkyl ether sulfate salt, and a phosphate salt. The amount of the emulsifier used may be determined depending on the type of the monomer. When the macromonomer described above has a stabilizing effect as a polymerization system of an emulsifier, an emulsifier may not be used. In the production method of the present invention, a chain transfer agent can be used to adjust the degree of polymerization (molecular weight) of the fluoropolymer. Further, the total concentration of the monomers in the aqueous medium can be increased. Examples of the chain transfer agent include alkyl mercaptan (tertiary-dodecyl mercaptan, n-dodecyl mercaptan, stearyl mercaptan, etc.), amino ethyl mercaptan, mercaptoethanol, and 3- Mercaptopropionic acid, 2-mercaptopropionic acid, thiomalic acid, thioglycolic acid, 3,3'-dithio-dipropionic acid, 2-ethylhexyl thioglycolate, n-butyl thioglycolate Ester, methoxybutyl thioglycolate, ethyl thioglycolate, 2,4-diphenyl-4-methyl-1-pentene, carbon tetrachloride, and the like. The amount of the chain transfer agent used is preferably from 0 to 2% by mass based on the monomer mixture. The polymerization method of the production method of the present invention is not particularly limited, and examples thereof include a batch polymerization method, a dropping polymerization method in which a monomer mixture is dropped, a continuous polymerization method, and the like. The aqueous coating material of the present invention contains the aqueous coating material of the aqueous dispersion of the present invention, which contains a salt component, and the content of the salt component is 0.01 to 0.22 mmol in terms of persulfate relative to 100 g of the fluoropolymer. The aqueous coating material of the present invention is usually obtained by diluting the above aqueous dispersion of the present invention with an aqueous medium or the like, and optionally containing an additive. The aqueous medium used for the dilution is the same as the aqueous medium described in the aqueous dispersion of the present invention. The amount of the aqueous medium to be used for the dilution is not particularly limited, and the content of the fluoropolymer in the aqueous coating material is preferably from 5 to 60% by mass, more preferably from 10 to 50%, based on the total amount of the aqueous coating material. The amount of mass %. When the content of the fluoropolymer is at the above lower limit, a coating film having more excellent weather resistance can be obtained, and when it is at the above upper limit, the transparency of the coating film is further improved. The content of the salt component in the water-based paint is 0.01 to 0.22 mmol, preferably 0.01 to 0.15 mmol, more preferably 0.01 to 0.10 mmol, and particularly preferably 0.01 to 100 g of the fluoropolymer in terms of persulfate. 0.05 mmol. When the content of the salt component is within the above range, the coloring of the aqueous coating material during storage or the decrease in the pH of the aqueous coating material can be suppressed. Further, when a water-based paint is prepared by adding various additives or the like to the aqueous dispersion, the salt component may be mixed. For example, when a fluoropolymer is added or another polymer is added, there is a case where a salt component derived from a polymerization initiator of the polymers is mixed. However, even in the case where a salt component is mixed from an additive or the like, the content of the salt component in the aqueous coating material of the present invention is preferably in the above range. The aqueous coating material of the present invention may contain other polymers, emulsifiers, and colorants other than the fluoropolymer in addition to the aqueous dispersion and the aqueous medium used for dilution, as long as the effects of the present invention are not impaired. , hardeners, other additives. For example, a coloring agent can be contained in the aqueous coating of the present invention. Moreover, since the aqueous coating material of the present invention contains a curing agent, the weather resistance, water resistance, chemical resistance, heat resistance and the like of the obtained coating film are further improved. The aqueous coating material of the present invention may be of a one-liquid type or a two-liquid type, and in the case of containing a hardening agent, it is preferably made into a two-liquid type, and the two liquids are mixed before being used. The other polymer is not particularly limited, and examples thereof include a (meth)acrylic polymer, a polyester resin, a polyurethane resin, an epoxy resin, and an acrylosterone resin. A melamine resin, a urea resin, an ethylene resin, a fluorine resin, a phenol resin, an alkyd resin, or the like. In the case where the other polymer is contained, the content of the other polymer in the aqueous coating material is preferably from 10 to 60% by mass. When the content of the other polymer is set to the above lower limit, the properties of the other polymer can be exhibited. On the other hand, if the content is the above upper limit, the properties of the fluoropolymer are not impaired. In order to improve emulsion stability, an emulsifier may also be added to the aqueous coating of the present invention. The type of the emulsifier contained in the aqueous coating is the same as that described in the aqueous dispersion of the present invention. Examples of the colorant include a dye, an organic pigment, an inorganic pigment, and the like. The content of the colorant is preferably from 1 to 300% by mass based on 100% of the total amount of the aqueous coating material. Examples of the curing agent include blocked isocyanate such as hexamethylene isocyanate trimer or an emulsified dispersion thereof; melamine resin such as methylated melamine, methylolated melamine or hydroxybutylated melamine; methylated urea And urea resin such as butylated urea. The content of the hardener is preferably from 10 to 150 mol% based on the total amount of the monomers used. Examples of other additives include plasticizers, ultraviolet absorbers, leveling agents, anti-shrinkage agents, anti-skinning agents, and the like. The coated article of the present invention has a coating film of the aqueous coating of the present invention on the surface of the article. The coated article of the present invention can be produced by coating the surface of the article with the aqueous coating of the present invention and drying it to form a coating film. The article is not particularly limited, and examples thereof include metal plates, wood boards, plastic plates, glass plates, asphalt, and concrete. Examples of the coating method include a method using a coating device such as a brush, a roll, a dipping, a spray, a roll coater, a die coater, an applicator, or a spin coater. The thickness of the coating film is preferably 5 to 50 μm. When the thickness of the coating film is the above lower limit value, a fluorescent coating film having high visibility and high design property can be obtained, and if it is the above upper limit value, there is no difference in the degree of curing between the surface layer of the coating film and the inside. Evenly coated film. The drying temperature after coating is preferably about 25 to 300 °C. According to the method for producing an aqueous dispersion of the present invention, since the amount of the persulfate used in the polymerization is small, the aqueous dispersion of the present invention having a small content of the salt component can be produced. Since the aqueous dispersion of the present invention has a small content of a salt component, it is excellent in coloring stability and pH stability. As described above, when an aqueous coating material is prepared from an aqueous dispersion, the viscosity is adjusted in many cases by adding a tackifier or the like in such a manner as to be the optimum viscosity of the coating material. It is known that the viscosity of the aqueous coating varies depending on the pH of the aqueous dispersion. If the pH value changes over time, the viscosity is adjusted to be optimal even when the aqueous coating is prepared, and the viscosity will change with the change of the pH. The viscosity changes from the optimum value when the water-based paint is used. Since the aqueous dispersion of the present invention is excellent in pH stability, when it is used as a water-based paint, the change in viscosity is small and the thixotropic property is excellent. Further, since the aqueous coating material of the present invention is excellent in thixotropic stability, the viscosity of the coating material is maintained in an optimum range, so that the article can be uniformly coated. Therefore, the aqueous coating material of the present invention and the coating film formed therewith are also excellent in color stability and uniformity. Further, the coating film formed of the aqueous coating material of the present invention prepared from the aqueous dispersion of the present invention containing the fluoropolymer of the unit 1 and the unit 2 is excellent in weather resistance, water resistance, chemical resistance, heat resistance and the like. . EXAMPLES The present invention will be specifically described by the following examples, but the present invention is not limited to the examples. The measurement methods used in the respective examples described below are shown below. <Measurement Method> [Calculation of Persulfate Amount] (Titration of Ammonium Ferric Sulfate (II) Added with Aqueous Dispersion) The aqueous dispersion W (g) was dissolved in 10 g of ion-exchanged water as a sample Solution. 20 mL of an aqueous solution of 90 g/L ammonium iron(II) sulfate and 20 mL of phosphoric acid were added to the sample solution to obtain a mixed solution. A 0.02 mol/L potassium permanganate aqueous solution was added dropwise to the mixture until the solution was reddish. The titration amount at this time was set to A (mL). (Titration of iron (II) ammonium sulfate) 20 g of an aqueous solution of 90 g/L ammonium iron(II) sulfate and 20 mL of phosphoric acid were added to 10 g of ion-exchanged water to obtain a mixed solution. A 0.02 mol/L potassium permanganate aqueous solution was added dropwise to the mixture until the solution was reddish. The titration amount at this time was set to B (mL). (Method for Calculating Persulfate Amount) First, the concentration C (% by mass) of the persulfate in the aqueous dispersion is calculated by the following formula (1). Furthermore, the concentration of persulfate in the aqueous coating can also be calculated in the same manner. C={(B-A)×f×Mw×0.00005/W}×100 (1) f: indicates the concentration of the 0.02 mol/L potassium permanganate aqueous solution, which is contained in the potassium permanganate aqueous solution. The amount of potassium permanganate is corrected. Mw: molecular weight of persulfate. Here, the titration described above is a method in which the persulfate in the sample solution and the iron (II) ammonium sulfate are subjected to a redox reaction in advance, and the excess ammonium ferric sulfate (II) is subjected to potassium permanganate. The amount of persulfate was determined by back titration. The redox reaction of ammonium (II) sulfate and potassium permanganate is represented by the following formula (61). 5FeSO4
(NH4
)2
SO4
+KMnO4
→5Fe3+
+10SO4 2-
+10NH4 +
+K+
+MnO4 6-
(61) The redox reaction of ammonium (II) sulfate and persulfate is as shown in the following formula (62). 2FeSO4
(NH4
)2
SO4
+QS2
O8
→2Fe3+
+4SO4 2-
+4NH4 +
+2SO4 2-
+Q (62) Q: Counter cations such as amines and alkali metals. The following formula (63) is derived from the titration amount A, the titration amount B, and the formula (61) and the formula (62) as a result of the above titration. C={(B-A)/1000×0.02×f×5/2×Mw/W}×100 (63) Equation (6) can be derived by calculating the constant of the equation (63). The specific value of f can be determined by a calibration method using a "standard substance" for volume analysis (hereinafter referred to as a direct method) or a "standard solution" for volume analysis having a factor determined by a direct method ( It is called indirect method) and is 1.003 in this measurement. Then, the amount Y (mmol) of residual persulfate per 100 g of the fluoropolymer solid content in the aqueous dispersion was calculated by the following formula (7). Y=(C/X)×100/Mw (7) X: Concentration (% by mass) of the fluoropolymer solid content component in the aqueous dispersion. [Calculation of Sulfate Ion Amount] The amount of sulfate ion which is a decomposition product of persulfate is calculated by the following procedure. Further, the amount of sulfate ion in the aqueous paint can also be calculated in the same manner. The sample solution obtained by diluting the produced aqueous dispersion by 1000 times with ultrapure water was placed in an ultrafilter, and a rotor having a radius of 13 cm ("H-18" manufactured by Kokusan Co., Ltd.) was used at 4000 rpm. The mixture was centrifuged for 60 minutes under the conditions. The filtrate was diluted 10-fold by ultrapure water to obtain a sample dilution. Then, the sulfate ion concentration I (μg/mL) in the diluted solution was measured using an ion chromatography system (manufactured by Nippon Dionex Co., Ltd., ICS-3000). From the results, the amount of sulfate ion (persulfate conversion) Z (mmol) per 100 g of the fluoropolymer solid content component in the aqueous dispersion was calculated by the following formula (8). Further, 96 in the formula is the molecular weight of the sulfate ion. Z = 10 × I / (d × X × 96) (8) d: specific gravity of the aqueous dispersion. X: concentration (% by mass) of the fluoropolymer solid content in the aqueous dispersion. [Measurement of yel (yellowness index)] The aqueous dispersions obtained in Examples 1 to 6 and Comparative Example 1 (immediately after production) were diluted to 10 times by ion-exchanged water, respectively. Dilute the sample. Load the diluted sample into the cylinder unit (30f
In the ×30 mm), the YI value was measured by a colorimetric color difference meter (manufactured by Nippon Denshoku Industries Co., Ltd., ZE-2000). Further, the aqueous dispersions obtained in Examples 1 to 6 and Comparative Example 1 were stored at 50 ° C for 2 weeks, and the YI value was measured in the same manner as above for the aqueous dispersion after storage. The lower the YI value, the less colored it is. [Measurement of pH] The pH of the aqueous dispersion obtained in Examples 1 to 6 and Comparative Example 1 (immediately after production) at 25 ° C was measured. Further, the aqueous dispersions obtained in Examples 1 to 6 and Comparative Example 1 were stored at 50 ° C for 2 weeks, and the aqueous dispersion after storage was also measured at a pH of 25 ° C. [Evaluation of Stability of Thixotropy] The aqueous dispersions of Examples 1 to 6 and Comparative Example 1 were respectively prepared with a film forming aid TEXANOL (manufactured by Eastman Chemical Co., Ltd.), an antifoaming agent Dehydran 1620 (manufactured by San Nopco Co., Ltd.), and a base. A water-based paint was prepared by blending a swellable tackifier TT-615 (manufactured by Rohm & Haas Co., Ltd.) and ammonia water. The amount of each material is adjusted such that the viscosity of the aqueous coating is thixotropy in a suitable range as the aqueous coating. The obtained aqueous coating material was stored at 50 ° C for 2 weeks, and the stability of thixotropy was evaluated according to the following criteria based on the thixotropy of each aqueous coating before and after storage. ○: Preservation did not result in a decrease in thixotropy. △: Preservation caused a slight decrease in thixotropy. ×: Preservation causes a significant decrease in thixotropy. Thixotropy of water-based paint: According to the cone-plate viscometer method specified in JIS K 5600-2-3, the rotor of No. 4 was used, and the water content at 5 rpm and 50 rpm was measured at 25 ° C. The viscosity of the coating was calculated as the TI value (= viscosity at 5 rpm (mPa·s) / viscosity at 50 rpm [mPa·s]), and used as an indicator of thixotropy. <Example 1> Into an autoclave equipped with a stainless steel mixer having a volume of 250 mL, cyclohexyl vinyl ether (hereinafter referred to as CHVE) 34 g, 2-ethylhexyl vinyl ether (hereinafter referred to as 2EHVE) 19 was charged. g, cyclohexanedimethanol monovinyl ether (hereinafter referred to as CHMVE) 2.8 g, 1-vinyloxymethyl-4-(polyoxyethylidene)cyclohexyl methyl ether (hereinafter referred to as CMEOVE) 1.7 g, Ion exchange water 93 g, potassium carbonate 0.26 g, ammonium persulfate (hereinafter referred to as APS) 0.012 g, nonionic emulsifier (DKS NL-100: manufactured by Daiichi Kogyo Co., Ltd.) 5.2 g, anionic emulsifier (Sodium lauryl sulfate; hereinafter referred to as SLS) 0.1 g, which was cooled by ice, and depressurized by nitrogen gas pressure to be 0.5 MPa. This pressurization degassing was repeated twice, and then degassed to -0.8 MPa to remove the dissolved air, and then pressed into CF.2
= CFCl (hereinafter referred to as CTFE) 47 g, and polymerization was carried out at 50 ° C for 36 hours. After the polymerization, the aqueous dispersion was filtered through a 200 mesh nylon cloth. Then, the ion-exchanged water was used, and the solid content concentration was adjusted to 52% by mass to obtain an aqueous dispersion containing a particulate fluoropolymer. The particles of the fluoropolymer have an average particle diameter of 150 nm. Further, the ethylene oxide adduct of the above CMEOVE-based CHMVE has an average number of oxygen-extended ethyl groups per molecule of about 15. (Examples 2 to 4 and Comparative Example 1) In the same manner as in Example 1, except that the amounts of APS used were changed as shown in Table 1 in Examples 2 to 4 and Comparative Example 1. An aqueous dispersion is obtained. The average particle diameter of the fluoropolymer in each case was in the range of 140 to 160 nm. <Example 5> An autoclave with a container of 250 mL of a stainless steel mixer was charged with 1.4 g of CHVE, 37 g of ethyl vinyl ether (hereinafter referred to as EVE), 3.8 g of CHMVE, and 3.1 g of CMEOVE. , 97 g of ion-exchanged water, 0.26 g of potassium carbonate, 0.0025 g of APS, 5.5 g of nonionic emulsifier (DKS NL-100: manufactured by Daiichi Kogyo Co., Ltd.), 0.1 g of SLS, The ice was cooled, and nitrogen gas was pressurized to be degassed so as to be 0.5 MPa. This pressurization degassing was repeated twice, and after degassing to -0.8 MPa and removing the dissolved air, 64 g of CTFE was injected, and the polymerization reaction was carried out at 50 ° C for 36 hours. After the polymerization, the aqueous dispersion was filtered through a 200 mesh nylon cloth. Then, the ion-exchanged water was used, and the solid content concentration was adjusted to 52% by mass to obtain an aqueous dispersion. <Example 6> A particle-like form was obtained in the same manner as in Example 3 except that the amount of addition of the nonionic emulsifier (DKS NL-100: manufactured by Daiichi Kogyo Co., Ltd.) was changed to 2.6 g. An aqueous dispersion of a fluoropolymer. The particles of the fluoropolymer have an average particle diameter of 210 nm. For each aqueous dispersion, the latex yield, the amount of persulfate, and the amount of sulfate ion were calculated. The latex yield represents a ratio (% by mass) of the amount of the solid content in the liquid after the polymerization reaction with respect to the ratio of the total amount of the raw materials other than the ion-exchanged water in the raw material (the same applies hereinafter). The content of the salt component (calculated as persulfate) is obtained by adding the amount of persulfate and the amount of sulfate ion. Further, the obtained aqueous dispersion was measured for chromaticity (YI value) and pH, and the stability of thixotropy was evaluated. The calculation result and the YI value of the amount of the raw material used in each of the examples and the content of the salt component of 100 g of the fluoropolymer (the total content of persulfate (APS) and its decomposition product (persulfate conversion)) The measurement results of the pH value and the evaluation results of the stability of the thixotropic properties are shown in Table 1. Further, regarding the YI value and the pH value, the absolute value of the difference between the value immediately after the production and the value stored at 50 ° C for 2 weeks is shown in Table 1. [Table 1]
In Comparative Example 1 in which the total content of persulfate (APS) and its decomposition product (persulfate conversion) of 100 g of the fluoropolymer in the aqueous dispersion was 0.24 mmol, the YI value immediately after the production was -5.8, the YI value after storage for 2 weeks at 50 ° C was 1.4, and the range of change was 7.2. On the other hand, in Examples 1 to 4 in which the total content (calculated as persulfate) was 0.22 mmol or less, the YI value immediately after the production was -6.4 or less, and the change in the YI value after storage at 50 ° C for 2 weeks was observed. The amplitude was -0.7 or less, which was lower than that of Comparative Example 1, and the coloring was suppressed. Moreover, the change in the YI value before and after storage is also small. In the examples 1 to 4, the lower the YI value of the embodiment in which the total content (persulfate conversion) of the fluoropolymer is lower than the total content of the fluoropolymer (100 g), the change in the YI value before and after storage. The smaller. In Example 5, in which the amount and the amount of the monomer were different, the total content (perpersulfate conversion) of 100 g of the fluoropolymer in the aqueous dispersion was 0.01 mmol. The YI value immediately after the manufacture of Example 5 was -11, and the YI value after storage for 2 weeks at 50 ° C was -9.7, which was also lower than that of Comparative Example 1. Also, the change in the YI value before and after storage is also small. Further, according to Comparative Example 6 of Example 3 in which the average particle diameter of the particles of the fluoropolymer is 200 nm or less and the average particle diameter of the particles of the fluoropolymer is 200 nm or more, the average particle diameter is 200. Below nm, the YI value immediately after manufacture, the YI value after storage for 2 weeks at 50 ° C, and the change in the YI value before and after storage are small, and coloring is suppressed. In Examples 1 to 6, the difference between the pH immediately after the production and the pH value after storage at 50 ° C for 2 weeks was smaller than that of Comparative Example 1. The aqueous coating materials using the aqueous dispersions of Examples 1 to 6 had less reduction in thixotropy when stored at 50 ° C for 2 weeks as compared with the aqueous coating material of Comparative Example 1. Further, in the case where the aqueous dispersion containing a fluoropolymer was produced in the same manner except that the amount of persulfate (APS) in Example 5 was set to a half amount (0.005 mmol), the latex yield was not reached. 90%, the fluoropolymer was not obtained efficiently. [Industrial Applicability] The aqueous coating material containing the aqueous dispersion of the present invention can be used, for example, for coating of metals such as wood used in construction and the like. In addition, the entire contents of the specification, the scope of the patent application, and the Abstract of the Japanese Patent Application No. 2016-005299, filed on Jan. 14, 2016, are hereby incorporated by reference.