TWI740880B - Fluorine-containing resin solution, fluorine-containing resin solution manufacturing method, coating composition and coated article - Google Patents

Abstract

The subject of the present invention is to provide a solution of a fluorine-containing resin that has excellent storage stability and can form a coating film with excellent gloss just after film formation. In addition, the subject of the present invention is also to provide a method for producing a fluorine-containing resin solution, a coating composition, and a coated article. The fluorine-containing resin solution of the present invention contains: a fluorine resin containing a fluorine-containing polymer having chlorotrifluoroethylene-based units, an amine group-containing compound, and an organic solvent, and is determined by the following chloride ion concentration measurement method The chloride ion concentration is below 50 mass ppm. Chloride ion concentration measurement method: The above-mentioned fluorine-containing resin solution and xylene are mixed to prepare a sample solution. After the obtained sample solution is mixed with water, the phase is separated into xylene phase and water phase, and the water phase is Recover and measure the chloride ion concentration in the recovered water by ion chromatography.

Description

Fluorine-containing resin solution, fluorine-containing resin solution manufacturing method, coating composition and coated article

The present invention relates to a fluorine-containing resin solution, a manufacturing method of a fluorine-containing resin solution, a coating composition and a coated article.

Previously, fluororesins obtained by homopolymerizing fluoroolefins or copolymerizing with other monomers have been known. A solution obtained by dissolving such a fluororesin in an organic solvent (a fluororesin solution) is used, for example, as a raw material for paint. As a solution of such a fluorine-containing resin, Patent Document 1 discloses a solution of a fluorine-containing resin, which contains: a fluorine-containing polymer having a fluoroolefin-based unit, and having 2,2,6,6-tetrasubstituted piperidine Based compounds, and organic solvents. Prior Art Documents Patent Documents Patent Document 1: International Publication No. 2015/056751 Specification

[Problems to be Solved by the Invention] In recent years, the performance of coating films has been required to further improve gloss. The inventors of the present invention used the fluorine-containing resin solution described in Patent Document 1 to produce a coating composition, and studied the gloss of the coating film obtained using the coating composition. As a result, it was confirmed that the gloss just after the film was formed was not satisfactory Recently requested higher grade; the fluorine-containing resin solution contains: a fluorine-containing resin containing a fluorine-containing polymer with units based on chlorotrifluoroethylene. The inventors of the present invention studied the cause and found that the decrease in gloss just after film formation is related to the concentration of chloride ions detected by the specific treatment of the fluorine-containing resin solution. In addition, the storage stability of the fluorine-containing resin solution is also required to be excellent. The present invention has been accomplished in view of the above-mentioned problems, and its object is to provide a solution of a fluorine-containing resin that has excellent storage stability and can form a coating film with excellent gloss just after film formation. In addition, the object of the present invention is also to provide a method for producing a fluorine-containing resin solution, a coating composition, and a coated article. [Technical Means to Solve the Problem] The present inventors have conducted intensive research on the above-mentioned problems and found that if a fluorine-containing resin solution with a chloride ion concentration below a specific value detected by the detection method described in detail below is used, it can be Obtain the desired effect, thereby achieving the invention. That is, the inventors of the present invention found that the above-mentioned problems can be solved by the following configuration. The present invention relates to the following inventions about a fluorine-containing resin solution, a method for producing a fluorine-containing resin solution, a coating composition, and a coated article. [1] A fluorine-containing resin solution containing: a fluorine resin containing a fluorine-containing polymer having chlorotrifluoroethylene-based units, an amine group-containing compound, and an organic solvent, and is measured by the following chloride ion concentration The chloride ion concentration determined by the method is 50 mass ppm or less. Chloride ion concentration measurement method: The above-mentioned fluorine-containing resin solution and xylene are mixed to prepare a sample solution. After the obtained sample solution is mixed with water, the phase is separated into xylene phase and water phase, and the water phase is Recover and measure the chloride ion concentration in the recovered water by ion chromatography. [2] The fluororesin solution of [1], wherein the content of the amine group-containing compound is 0.1 to 2.0 parts by mass relative to 100 parts by mass of the fluororesin. [3] The fluorine-containing resin solution of [1] or [2], wherein the content of the above-mentioned chlorotrifluoroethylene-based units is 40-60 mol% with respect to all the units of the above-mentioned fluorine-containing polymer. [4] The fluorine-containing resin solution of any one of [1] to [3], wherein the chloride ion concentration is 3 mass ppm or more. [5] A method for producing a fluorine-containing resin solution, characterized in that it is obtained by polymerizing monomer components containing chlorotrifluoroethylene in an organic solvent in the presence of an amine group-containing compound and hydrotalcite The fluoropolymer-containing mixed liquid is then removed from the above-mentioned fluoropolymer-containing mixed liquid to remove the insoluble components derived from the above-mentioned hydrotalcite to produce a fluorine-containing resin solution, and at the point in time when the above-mentioned monomer components start to polymerize, The ratio of the mass of the hydrotalcite to the mass of the amine group-containing compound (the mass of hydrotalcite/the mass of the amine group-containing compound) is set to 1 to 4. [6] The production method according to [5], wherein after the polymerization and before the filtration, the hydrotalcite is added to the mixed liquid containing the fluoropolymer. [7] The production method according to [5] or [6], wherein the amount of the amine group-containing compound at the start of polymerization is 0.1 to 2.0 parts by mass relative to 100 parts by mass of the monomer component. [8] The production method according to any one of [5] to [7], wherein the amount of chlorotrifluoroethylene in the monomer components is 40-60 mol% with respect to the total monomer components. [9] The production method according to any one of [5] to [8], wherein the solution of the fluorine-containing resin does not substantially contain hydrotalcite. [10] The production method according to any one of [5] to [9], wherein the chloride ion concentration in the solution of the fluorine-containing resin produced by the following chloride ion concentration measurement method is 50 mass ppm the following. Chloride ion concentration measurement method: The above-mentioned fluorine-containing resin solution and xylene are mixed to prepare a sample solution, the obtained sample solution is mixed with water, and the phases are separated into xylene phase and water phase. Recover and measure the chloride ion concentration in the recovered water by ion chromatography. [11] The production method according to [10], wherein the chloride ion concentration is 3 mass ppm or more. [12] A coating composition containing the fluorine-containing resin solution of any one of [1] to [4] above. [13] A coating composition comprising a fluororesin composition obtained by removing an organic solvent from the fluororesin solution of any one of [1] to [4] above. [14] The coating composition of [13], wherein the above-mentioned coating composition is a powdered coating composition. [15] A coated article having a substrate and a coating film formed on the substrate by the coating composition of any one of [12] to [14]. [Effects of the Invention] According to the present invention, it is possible to provide a fluorine-containing resin solution that has excellent storage stability and can form a coating film with excellent gloss just after film formation. Furthermore, according to the present invention, it is also possible to provide a method for producing a fluorine-containing resin solution, a coating composition, and a coated article.

其中，x為0.2〜0.33，m為0〜2。 所謂「(甲基)丙烯酸酯」係丙烯酸酯與甲基丙烯酸酯之總稱。 所謂「醚酯系溶劑」意指分子內具有醚鍵與酯鍵之兩者之化合物。 以下，對本發明之含氟樹脂之溶液、含氟樹脂之溶液之製造方法、塗料組合物及塗裝物品進行詳細說明。 [含氟樹脂之溶液] 本發明之含氟樹脂之溶液含有：包含具有基於氯三氟乙烯(CF₂ =CFCl，以下亦稱為「CTFE」)之單元之含氟聚合物之氟樹脂、含胺基之化合物及有機溶劑，且藉由以下之氯離子濃度測定法所求出之氯離子濃度為50質量ppm以下。 氯離子濃度測定法：將上述含氟樹脂之溶液與二甲苯加以混合而製備試樣溶液，將所獲得之試樣溶液與水混合後，相分離為二甲苯相與水相，將水相進行回收並藉由離子層析法對回收之水中之氯離子濃度進行測定。 再者，以下亦將上述氯離子濃度測定法稱為「特定之測定法」，所謂氯離子濃度意指藉由特定之測定法所求出之氯離子濃度。 本發明之含氟樹脂之溶液之儲藏穩定性優異，可形成剛成膜後之光澤性優異之塗膜。其詳細原因尚未明確，但認為大致係基於以下原因。 於本發明中，使用包含具有基於CTFE之單元之含氟聚合物之氟樹脂。 發明者等人依照專利文獻1所具體記載之方法，使用含有具有基於CTFE之單元之含氟聚合物的含氟樹脂之溶液製造塗料組合物，並對使用該塗料組合物而獲得之塗膜研究光澤性(參照下文所述之比較例1)。其結果，本發明者等人發現塗膜之剛成膜後之光澤性降低。 然後，本發明者等人發現，含氟樹脂之溶液之氯離子濃度與剛成膜後之塗膜光澤性之降低密切相關。具體而言，本發明者等人發現，亦如下文所述之實施例所示，若將氯離子濃度設為特定值以下，則可獲得剛成膜後之光澤性優異之塗膜。 再者，氯離子與塗膜之光澤性相關之詳細之原因尚不明確，認為基於如下原因等導致光澤性變差：於形成塗膜時，源自酸之成分(源自氯化氫之氯離子等)局部存在於塗膜表面而於塗膜表面與塗膜內部產生硬化速度之差；或於烘烤塗裝時之成膜前氟樹脂凝膠化而熔融流動性變差，未形成均勻之塗膜。 再者，所謂「剛成膜後」係指自塗膜之製作起24小時以內。 又，由於本發明之含氟樹脂之溶液含有含胺基之化合物，因此推測氟樹脂可穩定存在於溶液中。其結果，認為含氟樹脂之溶液之經時性之增黏等受到抑制，含氟樹脂之溶液之儲藏穩定性優異。 再者，專利文獻1中揭示有使用含胺基之化合物及水滑石製造含有具有基於CTFE之單元之含氟聚合物之含氟樹脂之溶液的具體態樣，但本發明者等人發現該態樣中之氯離子濃度較高。其原因未必明確，但認為如以下所述。 首先，認為該含氟樹脂之溶液所含之氯離子主要由CTFE聚合時發生之CTFE之分解所產生。 於此種存在氯離子之情況下，若存在含胺基之化合物，則於含胺基之化合物與氯離子之間形成鹽酸鹽。又，於此種情況下若存在水滑石，則氯離子亦被水滑石所吸附。即，於專利文獻1之具體態樣中，進行氯離子與含胺基之化合物形成鹽及氯離子向水滑石吸附這兩者。 水滑石於聚合後藉由過濾處理等自含氟聚合物分離。因此，被水滑石吸附之氯離子被去除至系統外。另一方面，與含胺基之化合物形成鹽之氯離子依然殘存於系統內。即，含氟樹脂之溶液所含之氯離子之量受到含胺基之化合物與水滑石之使用量所影響。具體而言，本發明者等人發現，於含胺基之化合物之使用量多於水滑石之使用量之情形時，與含胺基之化合物形成鹽之氯離子大量殘存於系統內，結果其氯離子濃度變高，因此無法獲得所需之效果。 於本發明中，如下文所詳細說明般，於製造含氟樹脂之溶液時，將水滑石之使用質量相對於含胺基之化合物之使用質量設為特定比率，對氯離子之系統外去除量與系統內殘存量進行控制，因此認為可降低含氟樹脂之溶液之氯離子濃度，結果可獲得所需之效果。 本發明中之含氟聚合物具有基於CTFE之單元，較佳為進而具有上述單元以外之單元(以下亦稱為其他單元)。 其他單元較佳為基於CTFE以外之氟烯烴之單元、基於具有交聯性基之單體(以下亦稱為「單體1」)之單元、或基於不具有氟原子及交聯性基之單體(以下亦稱為「單體2」)之單元，更佳為基於單體1之單元或基於單體2之單元。尤佳為含氟聚合物具有基於單體1之單元與基於單體2之單元兩者。 CTFE以外之氟烯烴所具有之氟原子數較佳為2以上，更佳為2〜6，進而較佳為3〜4。若該氟原子數為2以上，則所獲得之塗膜之耐候性優異。 CTFE以外之氟烯烴較佳為CF₂ =CF₂ 、CH₂ =CF₂ 、或CH₂ =CFCF₃ ，尤佳為CF₂ =CF₂ 。 CTFE以外之氟烯烴亦可使用兩種以上。 單體1係具有交聯性基之單體。 交聯性基較佳為具有活性氫之官能基(羥基、羧基、胺基等)、或水解性矽烷基(烷氧基矽烷基等)、環氧基或氧雜環丁基。 單體1較佳為式CH₂ =CX¹ (CH₂ )_n1 -Q¹ -R¹ -Y¹ 所表示之單體。其中，式中，X¹ 為氫原子或甲基，n1為0或1，Q¹ 為單鍵、醚性氧原子、-C(O)O-或-O(O)C-，R¹ 為碳數2〜20之伸烷基、碳數2〜20之含有醚性氧原子之伸烷基、或具有環結構之碳數6〜20之伸烷基，Y¹ 為交聯性基。 X¹ 較佳為氫原子。 n1較佳為0。 Q¹ 較佳為氧原子或-O(O)O-，較佳為氧原子。 R¹ 較佳為直鏈狀之碳數1〜10之伸烷基。該伸烷基之碳數更佳為1〜6，進而較佳為2〜4。 Y¹ 較佳為水解性矽烷基、羥基、羧基或胺基，更佳為羥基、羧基或胺基，進而較佳為羥基。 作為單體1之具體例，可列舉：羥基烷基乙烯基醚(2-羥基乙基乙烯基醚、羥基甲基乙烯基醚、4-羥基丁基乙烯基醚等)、羥基烷基乙烯基酯、羥基烷基烯丙基醚(羥基乙基烯丙基醚等)、羥基烷基烯丙基酯、(甲基)丙烯酸羥基烷基酯((甲基)丙烯酸羥基乙酯等)等。較佳為羥基烷基乙烯基酯、羥基烷基烯丙基酯中之羥基烷基及羥基烯丙基分別與酯鍵之羰基之碳原子鍵結。 單體1較佳為羥基烷基乙烯基醚、或羥基烷基烯丙基醚，就共聚性優異、所形成之塗膜之耐候性優異之方面而言，更佳為羥基烷基乙烯基醚，尤佳為4-羥基丁基乙烯基醚。 單體1亦可使用兩種以上。 單體2係不具有氟原子及交聯性基之單體。 作為單體2，較佳為式CH₂ =CX² (CH₂ )_n2 -Q² -R² 所表示之單體。其中，式中，X² 為氫原子或甲基，n2為0或1，Q² 為單鍵、氧原子、-C(O)O-或-O(O)C-，R² 為碳數2〜20之烷基、碳數2〜20之含有醚性氧原子之烷基、或具有環結構之碳數6〜20之烷基。 X² 較佳為氫原子。 n2較佳為0。 Q² 較佳為氧原子或-O(O)C-，較佳為氧原子。 R² 較佳為碳數1〜10之烷基、或具有環結構之碳數6〜20之烷基，更佳為碳數1〜6之烷基、或碳數6〜12之環烷基，尤佳為碳數2〜4之烷基、或碳數6〜10之環烷基。 作為單體2之具體例，可列舉：烷基乙烯基醚、環烷基乙烯基醚、烷基乙烯基酯、烷基烯丙基醚、烷基烯丙基酯、(甲基)丙烯酸烷基酯等。較佳為烷基乙烯基酯及烷基烯丙基酯中之烷基與酯鍵之羰基之碳原子鍵結。 單體2較佳為烷基乙烯基醚、或環烷基乙烯基醚，更佳為乙基乙烯基醚、環己基乙烯基醚、或2-乙基己基乙烯基醚，就氟樹脂之剛性較高、可溶於有機溶劑、於應用於塗料中之情形時容易施工、可獲得較硬之塗膜之方面而言，尤佳為環己基乙烯基醚。 單體2亦可使用兩種以上。 含氟聚合物中之基於CTFE之單元之比率相對於含氟聚合物所具有之全部單元，較佳為40〜60莫耳%，更佳為45〜55莫耳%。若該比率為40莫耳%以上，則所獲得之塗膜之耐候性優異。若該比率為60莫耳%以下，則於有機溶劑或稀釋劑中之溶解性優異。 於含氟聚合物具有基於單體1之單元及基於單體2之單元之情形時，其合計之比率相對於含氟聚合物所具有之全部單元，較佳為40〜60莫耳%，更佳為45〜55莫耳%。 因此，於基於CTFE之單元以外之單元僅為基於單體1之單元及基於單體2之單元之情形時，基於單體1之單元及基於單體2之單元之合計之比率相對於含氟聚合物所具有之全部單元，較佳為40〜60莫耳%，更佳為45〜55莫耳%。 具有基於單體1之單元之情形時之比率相對於含氟聚合物所具有之全部單元，較佳為5〜40莫耳%，更佳為8〜35莫耳%。若該比率為5莫耳%以上，則為了獲得硬度較高之塗膜所充分之量之交聯性基被導入至含氟聚合物中。若該比率為40莫耳%以下，則即便為高固形物成分型，亦可維持作為含氟樹脂之溶液所充分之低黏度。 具有基於單體2之單元之情形時之比率相對於含氟聚合物所具有之全部單元，較佳為超過0莫耳%且為45莫耳%以下，更佳為3〜45莫耳%，進而較佳為20〜45莫耳%。若具有該單元，則可適當調整所獲得之塗膜之硬度或柔軟性。若上述比率為45莫耳%以下，則容易於含氟聚合物中導入為了獲得耐候性優異、硬度較高之塗膜所充分之量之交聯性基。 於具有基於CTFE之單元、基於單體1之單元及基於單體2之單元以外之基於單體之單元之情形時，該單元之比率相對於含氟聚合物所具有之全部單元，較佳為20莫耳%以下，更佳為10莫耳%以下。 含氟聚合物之Mn較佳為3,000〜50,000，更佳為5,000〜30,000。若含氟聚合物之Mn為上述下限值以上，則塗膜之耐水性、耐鹽水性等優異。若含氟聚合物之Mn為上述上限值以下，則塗膜之表面平滑性優異。 再者，於本發明之含氟樹脂之溶液中實質上不含水滑石。所謂實質上不含水滑石意指本發明之含氟脂之溶液所含之水滑石量未達0.1質量%，通常較佳為0.01質量%以下。水滑石量之下限為0質量%。 本發明中之含胺基之化合物只要為含有胺基之化合物，則並無特別限定。再者，於本說明書中，上述「含胺基之化合物」中亦包括與氯化氫(HCl)形成鹽之態樣。即，上述「含胺基之化合物」中亦包括含胺基之化合物之鹽酸鹽。 作為胺基，可列舉：一級胺基(-NH₂ )、二級胺基、三級胺基。 二級胺基係式-NHR^N (R^N 為一價取代基)所表示之單取代胺基，作為R^N 之具體例，可列舉：烷基、芳基、乙醯基、苯甲醯基、苯磺醯基、第三丁氧基羰基等。作為二級胺基之具體例，可列舉：甲基胺基、乙基胺基、丙基胺基、異丙基胺基等R為烷基之二級胺基；或苯基胺基、萘基胺基等R為芳基之二級胺基等。又，R^N 中氫原子亦可進一步經乙醯基、苯甲醯基、苯磺醯基、第三丁氧基羰基等所取代。 三級胺基為式-NR^N1 R^N2 (R^N1 及R^N2 為一價取代基)所表示之二取代胺基，作為R^N1 及R^N2 之具體例，與R^N 相同。作為三級胺基之具體例，可列舉：二甲胺基、二乙胺基、二丁胺基、乙基甲基胺基、二苯基胺基、甲基苯基胺基等。 作為胺基，亦可列舉脂環式胺基。脂環式胺基係環內至少含有1個氮原子之脂環基。 作為脂環式胺基，較佳為吡咯啶基、哌啶基、哌𠯤基、氮雜環庚烷基等5〜7員環之脂環式胺基，尤佳為6員環之脂環式胺基(哌啶基)。又，脂環式胺基中之氫原子可進一步經取代基(烷基、芳基等)所取代。 6員環之脂環式胺基較佳為哌啶基或具有取代基之哌啶基，更佳為具有取代基之哌啶基，進而較佳為四取代哌啶基，尤佳為2,2,6,6-四取代哌啶基。 含胺基之化合物亦可使用兩種以上。 含胺基之化合物較佳為下式所表示之化合物(具有2,2,6,6-四取代哌啶基之化合物)。 [化1]

R¹¹ 〜R¹⁴ 分別獨立為碳數1〜18之烷基(甲基、乙基、丙基、十二烷基、硬脂基等)、環烷基(環戊基、環己基等)、取代烷基(2-羥基乙基、2-甲氧基羰基乙基、3-羥基丙基等)、芳基(苯基、萘基等)或芳烷基(苯乙基、苄基等)，R¹¹ 及R¹² 、或R¹³ 及R¹⁴ 可形成碳數3〜6之脂肪族環。作為R¹¹ 〜R¹⁴ ，就價格、獲得容易性之方面而言，較佳為碳數1〜18之烷基，尤佳為甲基。 R¹⁵ 為氫原子、烷基(甲基、乙基、丙基、丁基、十二烷基、硬脂基等)、取代烷基(2-羥基乙基、2-甲氧基羰基乙基、2-乙醯氧基乙基、2-(3-甲氧基羰基丙醯氧基)乙基、3-羥基丙基等)、芳基(苯基、萘基、羥基苯基等)、芳烷基(苯乙基、苄基、羥基苯基烷基等)或環烷基(環己基等)。 R¹⁶ 為氫原子、羥基、烷基(甲基、乙基、丙基、丁基、十二烷基、硬脂基等)、取代烷基(2-羥基乙基、2-甲氧基羰基乙基、2-乙醯氧基乙基、2-(3-甲氧基羰基丙醯氧基)乙基、3-羥基丙基等)、芳基(苯基、萘基等)、芳烷基(苯乙基、苄基等)、含酯鍵之基(乙醯氧基、丙醯氧基、丁醯氧基、月桂醯氧基、取代烷基羰氧基、苯甲醯氧基、取代苯甲醯氧基等)、含胺基之基(烷氧基羰基胺基、N-單烷基胺甲醯基胺基、N,N-二烷基胺甲醯基胺基等)或含2,2,6,6-四取代哌啶基之基。R¹⁶ 可組合該等基兩種以上。 作為含胺基之化合物之具體例，可列舉：2,2,6,6-四甲基哌啶、1,2,2,6,6-五甲基哌啶、4-羥基-2,2,6,6-四甲基哌啶、4-羥基-1,2,2,6,6-五甲基哌啶、1-乙基-2,2,6,6-四甲基哌啶、1-乙基-4-羥基-2,2,6,6-四甲基哌啶、1-丁基-4-羥基-2,2,6,6-四甲基哌啶、1-十二烷基-2,2,6,6-四甲基哌啶、1-苯基-2,2,6,6-四甲基哌啶、1-(2-羥基乙基)-2,2,6,6-四甲基哌啶、1-(6-羥基乙基)-4-羥基-2,2,6,6-四甲基哌啶、4-乙醯氧基-2,2,6,6-四甲基哌啶、4-乙醯氧基-1,2,2,6,6-五甲基哌啶、1-(2-乙醯氧基乙基)-4-乙醯氧基-2,2,6,6-四甲基哌啶、1-(2-苯甲醯氧基乙基)-4-苯甲醯氧基-2,2,6,6-四甲基哌啶、4-乙基-2,2,6,6-四甲基哌啶、4-乙基-1,2,2,6,6-五甲基哌啶、4-丁基-2,2,6,6-四甲基哌啶、4-辛基-2,2,6,6-四甲基哌啶、4-十二烷基-2,2,6,6-四甲基哌啶、4-硬脂基-2,2,6,6-四甲基哌啶、4-硬脂基-1,2,2,6,6-五甲基哌啶、癸二酸甲酯1,2,2,6,6-五甲基-4-哌啶酯、癸二酸雙(2,2,6,6-四甲基-4-哌啶基)酯等。 作為R¹⁶ 為含2,2,6,6-四取代哌啶基之基之含胺基之化合物，可列舉使具有羥基之2,2,6,6-四甲基哌啶(4-羥基-2,2,6,6-四甲基哌啶、4-羥基-1,2,2,6,6-五甲基哌啶、1-(2-羥基乙基)-4-羥基-2,2,6,6-四甲基哌啶、1-(2-羥基乙基)-2,2,6,6-四甲基哌啶等)與多元酸(琥珀酸、己二酸、癸二酸、壬二酸、癸烷-1,10-二羧酸、鄰苯二甲酸、間苯二甲酸、對苯二甲酸、偏苯三甲酸、丙二酸、取代丙二酸等)進行反應而獲得之1分子中含有2個以上之2,2,6,6-四甲基哌啶基之含胺基之化合物，具體而言，可列舉下式所表示之化合物。 其中，n3為1〜20之整數。 [化2]

含胺基之化合物之含量相對於上述氟樹脂100質量份，較佳為0.1〜2.0質量份，更佳為0.5〜2.0質量份，進而較佳為0.5〜1.5質量份。若該含量為0.1質量份以上，則於單體成分之聚合中或聚合後，含氟樹脂之溶液變得更不易凝膠化，含氟樹脂之溶液之儲藏穩定性更優異。又，若該含量為2.0質量份以下，則含氟樹脂之溶液於儲藏中之溶液之變色(例如黃變或白濁等)或含氟聚合物之分子量之增大進一步受到抑制，含氟樹脂之溶液之儲藏穩定性更優異。 本發明中之有機溶劑只要為可溶解氟樹脂之有機溶劑，則並無特別限定，較佳為選自由芳香族烴系溶劑、酮系溶劑、酯系溶劑、醇系溶劑、醚酯系溶劑所組成之群之一種以上之有機溶劑。 芳香族烴系溶劑較佳為甲苯、二甲苯、乙基苯、芳香族石腦油、萘滿、或松節油。芳香族烴系溶劑可使用市售品，可使用Solvesso(註冊商標)#100(Exxon Chemical公司製造)、Solvesso(註冊商標)#150(Exxon Chemical公司製造)等。 酮系溶劑較佳為丙酮、甲基乙基酮、甲基戊基酮、甲基異丁基酮、乙基異丁基酮、二異丁基酮、環己酮、或異佛酮。 酯系溶劑較佳為乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸異丁酯、或乙酸第三丁酯。 醇系溶劑較佳為碳數4以下之醇，較佳為乙醇、第三丁醇、或異丙醇。 醚酯系溶劑較佳為3-乙氧基丙酸乙酯、丙二醇單甲醚乙酸酯、或乙酸甲氧基丁酯。 有機溶劑亦可使用兩種以上。又，有機溶劑可為與用作聚合溶劑之有機溶劑相同之有機溶劑，亦可為與之不同之有機溶劑。 有機溶劑之含量就氟樹脂之溶解性變得良好之觀點而言，較佳為以含氟樹脂之溶液中之固形物成分濃度成為40〜80質量%之方式含有。 本發明之含氟樹脂之溶液亦可於可充分發揮本發明之效果之範圍內含有上述以外之成分(例如，丙烯酸系樹脂或聚酯樹脂等通用樹脂成分)。 本發明之含氟樹脂之溶液藉由特定之測定法所求出之氯離子濃度為50質量ppm以下。氯離子濃度更佳為40質量ppm以下，進而較佳為30質量ppm以下，尤佳為10質量ppm以下。下限值較佳為1質量ppm，尤佳為3質量ppm。 若氯離子濃度為50質量ppm以下，則使用本發明之含氟樹脂之溶液所獲得之塗膜剛成膜後之光澤性優異。另一方面，若上述氯離子濃度超過50質量ppm，則剛成膜後之光澤性變得不充分。 尤其是若氯離子濃度為3〜30質量ppm，則使用含氟樹脂之溶液所獲得之塗料組合物之流動性亦優異。若使用含氟樹脂之溶液所獲得之塗料組合物之流動性優異，則於將塗裝於基材之粉體組合物熔融而形成塗膜(硬化膜)時，塗料組合物之流動性提高，因此就可獲得平滑且均勻之塗膜(硬化膜)之方面而言較佳。 若氯離子濃度為30質量ppm以下，則可抑制由含氟樹脂之溶液之粉體化(脫溶劑)或烘烤塗裝時之熱引起之氯化氫之產生。推測藉此塗料組合物所含之氟樹脂之凝膠化受到抑制，塗料組合物之流動性提高。 於本發明中，氯離子濃度係藉由特定之測定法測定，即，將本發明之含氟樹脂之溶液與二甲苯加以混合而製備試樣溶液，將所獲得之試樣溶液與水混合後，相分離為二甲苯相與水相，將水相進行回收並藉由離子層析法對回收之水中之氯離子濃度進行測定。 更詳細而言，氯離子濃度係以如下方式進行測定。 首先，將本發明之含氟樹脂之溶液與二甲苯進行混合及攪拌而獲得試樣溶液。再者，含氟樹脂之溶液之量相對於二甲苯之量5 mL設為0.5 g。 繼而，將試樣溶液與純水進行混合及攪拌而獲得混合液。再者，純水之量相對於試樣溶液之添加量4.9 g設為3 mL。 繼而，將混合液進行離心分離而將混合液相分離為水相與二甲苯相，去除二甲苯相而獲得分離液。進而，將分離液進行離心分離而使其相分離為殘留二甲苯(二甲苯相)與水(水相)，去除二甲苯相，將水相回收。 繼而，製備於所回收之水(水相)中添加純水稀釋而成之測定液，藉由離子層析法對氯離子濃度進行測定。 再者，於任一離心分離中均使用公知之離心分離裝置(具體而言為依照久保田製作所製造之商品名「台式冷卻離心機5500」之裝置)，離心分離之條件設為於12000 rpm下5分鐘。 又，利用離子層析法進行之測定例如係使用依照離子層析儀ICS-1500(商品名，Dionex公司製造)之裝置進行測定。 利用離子層析法測得之氯離子濃度之具體之測定條件如下所述。再者，以相對於濃度已知之標準液之峰面積比測定檢測量，並換算氯離子(Cl^- )之量。又，氯離子(Cl^- )之定量極限為0.6 ppm以下。 ＜離子層析儀條件＞ 裝置：使用Dionex公司製造之ICS-1500抑制器 分析管柱：Dionex IonPac AS14  內徑4.0 mm×長度50 mm 保護管柱：Dionex IonPac AG14  內徑4.0 mm×長度250 mm 溶離液：3.5 mmol Na₂ CO₃ 、1.0 mmol NaHCO₃ 流量：1.5 ml/min [含氟樹脂之溶液之製造方法] 本發明之含氟樹脂之溶液之製造方法係如下方法：於含胺基之化合物及水滑石之存在下，使包含CTFE之單體成分於有機溶劑中進行聚合而獲得含有含氟聚合物之混合液，繼而自上述含有含氟聚合物之混合液去除源自上述水滑石之不溶解成分而製造含氟樹脂之溶液。 又，於單體成分開始聚合之時間點，水滑石之量相對於含胺基之化合物之量之比率(水滑石之量/含胺基之化合物之量)為1〜4。 進而，藉由特定之測定法所求出之氯離子濃度較佳為50質量ppm以下。 根據本發明之含氟樹脂之溶液之製造方法，可獲得儲藏穩定性優異之含氟樹脂之溶液，可形成剛成膜後之光澤性優異之塗膜。 以下，將進行聚合之步驟稱為聚合步驟、進行過濾之步驟稱為過濾步驟，對各步驟進行詳細說明。 藉由所謂之溶液聚合法使聚合步驟中之單體成分進行聚合。各成分於聚合系統中之添加順序可適當選擇。作為單體成分，除了CTFE以外，亦可使用單體1及單體2。 關於聚合步驟中之含胺基之化合物、CTFE、及氟樹脂之詳細內容如上所述，省略其說明。 作為有機溶劑，可列舉與含氟樹脂之溶液一項所記載之有機溶劑相同之有機溶劑。聚合步驟中之有機溶劑可與本發明之含氟樹脂之溶液所含之有機溶劑相同，亦可與之不同。 聚合步驟中之水滑石就氯離子之吸附性優異之方面及容易獲得之方面而言，較佳為Mg₆ Al₂ (OH)₁₆ CO₃ ·4H₂ O(於上述之表示水滑石之式中，x＝0.25，m＝0.5)、或Mg_4.5 Al₂ (OH)₁₃ CO₃ ·3.5H₂ O(於上述之表示水滑石之式中，x＝0.308，m＝0.538)。 水滑石亦可使用兩種以上。 水滑石之粒徑較佳為5〜500 μm，更佳為5〜110 μm。若水滑石之粒徑為5 μm以上，則變得容易利用過濾進行去除。若水滑石之粒徑為500 μm以下，則每單位質量之表面積較大，進一步發揮由水滑石獲得之效果。 水滑石之粒徑係依照JIS K 0069之「化學製品之篩分試驗方法」而測定。 於聚合步驟中，較佳為藉由聚合起始劑之作用使單體成分進行聚合。 作為聚合起始劑，可列舉：偶氮系起始劑(2,2'-偶氮雙異丁腈、2,2'-偶氮雙環己腈、2,2'-偶氮雙(2,4-二甲基戊腈)、2,2'-偶氮雙(2-甲基丁腈)等)、過氧化物系起始劑{過氧化酮(過氧化環己酮等)、過氧化氫(第三丁基過氧化氫等)、過氧化二醯基(過氧化苯甲醯等)、過氧化二烷基(過氧化二第三丁基等)、過氧縮酮(2,2-二-(第三丁基過氧基)丁烷等)、烷基過氧化酯(過氧化特戊酸第三丁酯等)、過氧化碳酸酯(過氧化二碳酸二異丙酯等)}。 於聚合步驟之開始聚合之時間點，水滑石之質量相對於含胺基之化合物之質量(水滑石之質量/含胺基之化合物之質量)之比率為1〜4，較佳為1.0〜3，尤佳為1.0〜2。 若該比率為1以上，則如含氟樹脂之溶液一項所記載，可將氯離子濃度調整為特定範圍，剛成膜後之塗膜之光澤性優異。又，若該比率為4以下，則於過濾步驟中去除不溶解成分時容易抑制過濾材料之堵塞。 含胺基之化合物之量相對於單體成分100質量份，較佳為0.1〜2.0質量份，更佳為0.5〜2.0質量份，進而較佳為0.5〜1.5質量份。若該量為0.1質量份以上，則於單體成分之聚合中或聚合後，含氟樹脂之溶液變得更不易凝膠化，含氟樹脂之溶液之儲藏穩定性更優異。又，若該量為2.0質量份以下，則含氟樹脂之溶液於儲藏中之溶液之變色(例如黃變或白濁等)或氟樹脂之分子量之增大進一步受到抑制，含氟樹脂之溶液之儲藏穩定性更優異。 單體成分中之CTFE之量相對於全部單體成分，較佳為40〜60莫耳%，更佳為45〜55莫耳%。若CTFE之量為40莫耳%以上，則所獲得之塗膜之耐候性優異。若CTFE之量為60莫耳%以下，則於有機溶劑或稀釋劑中之溶解性優異。 於含有單體1及單體2作為單體成分之情形時，其合計量相對於全部單體成分，較佳為40〜60莫耳%，更佳為45〜55莫耳%。 因此，於CTFE以外之單體成分僅為單體1及單體2之情形時，單體1及單體2之合計量相對於全部單體成分，較佳為40〜60莫耳%，更佳為45〜55莫耳%。 單體成分中之單體1之量相對於全部單體成分，較佳為5〜40莫耳%，更佳為8〜35莫耳%。若該量為5莫耳%以上，則為了獲得硬度較高之塗膜所充分之量之交聯性基被導入至含氟聚合物。若該量為40莫耳%以下，則即便為高固形物成分型，亦可作為含氟樹脂之溶液而維持低黏度。 單體成分中之單體2之量相對於全部單體成分，較佳為超過0莫耳%且為45莫耳%以下，更佳為3〜45莫耳%，進而較佳為20〜45莫耳%。若使用單體2，則可適當調整所獲得之塗膜之硬度或柔軟性。若該量為45莫耳%以下，則容易於含氟聚合物中導入為了獲得耐候性優異、硬度較高之塗膜所充分之量之交聯性基。 於含有CTFE、單體1及單體2以外之單體的單體成分之情形時，該單體之量相對於全部單體成分，較佳為20莫耳%以下，更佳為10莫耳%以下。 於本發明中之過濾步驟中，將作為不溶於有機溶劑之不溶解成分之吸附有聚合步驟中產生之氯離子的水滑石(即源自水滑石之不溶解成分)去除。去除係藉由過濾等固液分離處理進行。 藉由以上之本發明之製造方法所獲得之含氟樹脂之溶液較佳為藉由特定之測定法測得之氯離子濃度為50質量ppm以下。關於氯離子濃度之更佳之範圍及效果，如含氟樹脂之溶液一項所說明，因此省略其說明。 又，藉由本發明之製造方法而獲得之含氟樹脂之溶液較佳為實質上不含水滑石。所謂實質上不含水滑石意指含氟脂之溶液所含之水滑石量未達0.1質量%，通常較佳為0.01質量%以下。水滑石量之下限為0質量%。 於本發明之製造方法中，亦可於聚合步驟後且過濾步驟前於含有含氟聚合物之混合液中添加水滑石。進而，於添加水滑石後且過濾步驟前亦可進行攪拌處理。藉此，可進一步降低上述氯離子濃度，所獲得之塗膜之剛成膜後之光澤性更優異。又，亦有含氟樹脂之溶液之儲藏穩定性更優異之傾向。 所添加之水滑石之量相對於所產生之含氟聚合物100質量份，較佳為0.1〜3.0質量份，更佳為0.5〜2.0質量份。若該量處於上述範圍內，則進一步表現上述之效果。 [塗料組合物] 本發明之塗料組合物係使用本發明之含氟樹脂之溶液而獲得之塗料組合物。本發明之塗料組合物可為液狀，亦可為粉末狀(所謂之粉體塗料組合物)。 液狀之塗料組合物係含有上述之含氟樹脂之溶液之塗料組合物，較佳為除了含氟樹脂之溶液以外亦含有硬化劑。 作為硬化劑，可列舉：異氰酸酯系硬化劑、封端化異氰酸酯系硬化劑、或胺基樹脂。 異氰酸酯系硬化劑較佳為無黃變異氰酸酯(例如，六亞甲基二異氰酸酯、異佛酮二異氰酸酯等)。 封端化異氰酸酯系硬化劑較佳為藉由己內醯胺、異佛酮、β-二酮等將異氰酸酯系硬化劑之異氰酸基進行封端而成之硬化劑。 胺基樹脂係胺(三聚氰胺、三聚氰二胺、脲等)與醛(甲醛等)之反應產物(羥甲基三聚氰胺等)或其衍生物(烷基醚化羥甲基三聚氰胺等)。作為胺基樹脂，可列舉：三聚氰胺樹脂、三聚氰二胺樹脂、脲樹脂、磺醯胺樹脂、苯胺樹脂等。 硬化劑之含量相對於塗料組合物中之氟樹脂100質量份，較佳為1〜100質量份，更佳為1〜50質量份。若硬化劑為1質量份以上，則塗膜之耐溶劑性與硬度優異。若為100質量份以下，則塗膜之加工性與耐衝擊性優異。 液狀之塗料組合物亦可進一步含有上述以外之成分。作為此種成分，可列舉：著色劑、上述之氟樹脂以外之樹脂、矽烷偶合劑、紫外線吸收劑、硬化觸媒等。 又，本發明之塗料組合物亦可為含有自本發明之含氟樹脂之溶液去除上述有機溶劑而成之氟樹脂組合物的塗料組合物。該塗料組合物亦可為使該氟樹脂組合物溶解於溶劑或分散於分散介質而獲得之液狀之塗料組合物。較佳為含有不含上述有機溶劑等液狀介質之氟樹脂組合物之塗料組合物。作為含有不含液狀介質之氟樹脂組合物之塗料組合物，較佳為粉末狀之塗料組合物(所謂之粉體塗料組合物)。 粉末狀之塗料組合物含有自本發明之含氟樹脂之溶液去除上述有機溶劑而製成粉末狀之氟樹脂組合物。粉末狀之氟樹脂組合物可對本發明之含氟樹脂之組合物實施乾燥處理及粉碎處理等公知之處理而製造。 粉末狀之塗料組合物較佳為除了上述氟樹脂組合物以外亦含有硬化劑。關於硬化劑，與上述之液狀之塗料組合物相同，省略說明。 又，粉末狀之塗料組合物可進一步含有上述以外之成分。作為此種成分，與上述之液狀之塗料組合物相同，省略說明。 [塗裝物品] 本發明之塗裝物品具有基材、及藉由上述塗料組合物而形成於上述基材上之塗膜。 作為塗裝方法，例如可列舉：噴塗、空氣噴塗、刷塗、浸漬法、靜電塗裝法、輥塗、流塗等方法。 塗膜亦可為塗裝於基材後實施公知之熔融處理而獲得之膜(熔融膜)。 作為基材之材質，可列舉無機物、有機物、有機無機複合材料等。作為無機物，可列舉混凝土、自然石、玻璃、金屬(鐵、不鏽鋼、鋁、銅、黃銅、鈦等)等。作為有機物，可列舉塑膠、橡膠、接著劑、木材等。作為有機無機複合材料，可列舉纖維強化塑膠、樹脂強化混凝土、纖維強化混凝土等。 基材之形狀、尺寸等並無特別限定。 作為本發明之塗裝物品之用途，可列舉：運輸用機件(汽車、電車、飛機等)、土木構件(橋樑構件、鐵塔等)、產業機件(防水材片材、槽、管等)、建築構件(樓房外裝、門、窗門構件、紀念碑、桿等)、道路構件(道路之中央隔離帶、護軌、隔音壁等)、通信機件、電氣機件、電子機件、太陽電池模組用表面片材、太陽電池模組用背面片材等。 實施例 以下，列舉實施例對本發明進行詳細說明。但本發明並不限定於該等實施例。 下文所述之表中之各成分之調配量表示質量基準。 含氟樹脂之溶液之固形物成分濃度係藉由JIS K 5601-1-2(2009年制定)測定加熱殘餘物而求出。 含氟樹脂之溶液所含之氟樹脂之Mn係藉由GPC(Tosoh公司製造，HLC-8220)進行測定。使用四氫呋喃作為展開溶劑，使用聚苯乙烯作為標準物質。 [含氟樹脂之溶液] 實施例及比較例之各含氟樹脂之溶液係以如下方式製備。 ＜實施例1之含氟樹脂之溶液之製備＞ 於安裝有攪拌機之內容積2500 mL之不鏽鋼製耐壓反應器中添加7.32 g之含胺基之化合物(BASF製造，商品名「TINUVIN292」，癸二酸雙(1,2,2,6,6-五甲基-4-哌啶基)酯與癸二酸甲酯1,2,2,6,6-五甲基-4-哌啶酯之混合物(質量比3：1))、7.32 g之水滑石(協和化學工業公司製造，商品名「KW500」，粒徑：45 μm以下：38%、45〜7 μm：35%、75〜106 μm：21%、106〜500 μm：6%)、746 g之二甲苯、153 g之4-羥基丁基乙烯基醚、601 g之環己基乙烯基醚，藉由利用氮氣進行之脫氣而去除溶液中之溶氧。進而，於上述反應器中導入701 g之CTFE，逐漸升溫，於溫度達到65℃之時間點間歇性地添加4.1 g之過氧化特戊酸第三丁酯(聚合起始劑)，藉此進行聚合。 24小時後，將反應器進行水冷而停止反應。將反應液冷卻至室溫後，清除未反應單體，藉由以矽藻土作為濾材之過濾將所獲得之反應液之不溶解成分去除，進而添加適量二甲苯，獲得固形物成分濃度60.0%之實施例1之含氟樹脂之溶液。 再者，實施例1之含氟樹脂之溶液所含之含氟聚合物之Mn為15500。 ＜實施例2之含氟樹脂之溶液之製備＞ 以與實施例1之含氟樹脂之溶液之製備同樣之方式進行聚合，於所獲得之反應液中進一步添加水滑石KW500，攪拌1小時後，藉由以矽藻土作為濾材之過濾將不溶解成分去除，進而添加適量二甲苯，獲得固形物成分濃度60.0%之實施例2之含氟樹脂之溶液。 再者，實施例2之含氟樹脂之溶液所含之含氟聚合物之Mn為15500。 ＜實施例3〜5及比較例1之含氟樹脂之溶液之製備＞ 將聚合時所添加之含胺基之化合物及水滑石之至少一者之添加量變更為第1表所記載之量，除此以外，進行與實施例1之含氟樹脂之溶液之製備同樣之操作，獲得實施例3〜5及比較例1之含氟之樹脂溶液。 再者，實施例3〜5及比較例1之含氟樹脂之溶液所含之含氟聚合物之Mn分別為15100、14900、14800、15400。 ＜實施例6〜7＞ 將聚合時所添加之含胺基之化合物由TINUVIN292變更為TINUVIN770DF(商品名，BASF製造，癸二酸雙(2,2,6,6-四甲基-4-哌啶基)酯)或二乙醇胺，將含胺基之化合物及水滑石之添加量設為第1表所記載之量，除此以外，進行與實施例1之含氟之溶液之製備同樣之操作，獲得實施例6〜7之含氟之樹脂溶液。 再者，實施例6〜7之含氟樹脂之溶液所含之含氟聚合物之Mn分別為15000、14900。又，以上之各例中獲得之含氟樹脂之溶液中之水滑石之含量為0.01質量%以下。 ＜比較例2之含氟樹脂之溶液之製備＞ 於聚合時不添加含胺基之化合物，除此以外，進行與實施例1之含氟樹脂之溶液之製備同樣之操作，獲得比較例2之含氟樹脂之溶液。 再者，比較例2之含氟樹脂之溶液所含之含氟聚合物之Mn為16400。 ＜比較例3之含氟樹脂之溶液之製備＞ 將聚合時所添加之含胺基之化合物之添加量變更為第1表所記載之量，於聚合時不添加水滑石，除此以外，進行與實施例2之含氟樹脂之溶液之製備同樣之操作，獲得比較例3之含氟樹脂之溶液。 再者，比較例3之含氟樹脂之溶液所含之含氟聚合物之Mn為15600。 ＜氯離子濃度＞ 藉由以下程序測定各含氟樹脂之溶液之氯離子濃度。 將各含氟樹脂之溶液0.5 g與二甲苯5 mL裝入至PP(聚丙烯)管中，用手振盪1分鐘而獲得含氟樹脂之溶液被二甲苯完全溶解而成之試樣溶液。 繼而，於試樣溶液中添加純水3 mL，用手劇烈振盪而獲得混合液。 繼而，將混合液進行離心分離，相分離為水與二甲苯後，使用微量吸管自混合液去除二甲苯相(上層)。 進而，對去除了二甲苯相之混合液進行離心分離，使其分離為殘留二甲苯(二甲苯相)與水(水相)。任一離心分離均使用離心分離裝置(商品名「台式冷卻離心機5500」，久保田公司製造)，於12000 rpm下進行5分鐘。 繼而，準備以純水將分離回收之水(水層)稀釋5倍或10倍而成之測定液，藉由離子層析法對測定液之氯離子濃度進行測定。利用離子層析法進行之測定係使用離子層析儀ICS-3000(商品名，Thermo Fisher公司製造)進行。利用離子層析法之測定條件如以下所述。 具體而言，以相對於濃度已知之標準液之峰面積比測定檢測量，並換算氯離子(Cl^- )之量。再者，定量極限以氯離子(Cl^- )計為0.6 ppm以下。 (離子層析儀條件) 裝置：使用Dionex製造之ICS-1500抑制器 分析管柱：Dionex IonPac AS14  內徑4.0 mm×長度50 mm 保護管柱：Dionex IonPac AG14  內徑4.0 mm×長度250 mm 溶離液：3.5 mmol Na₂ CO₃ 、1.0 mmol NaHCO₃ 流量：1.5 mL/min 將以上之氯離子濃度之測定結果彙總示於第1表。 [評價試驗] 使用各含氟樹脂之溶液，實施以下之評價試驗。 ＜儲藏穩定性＞ 將各含氟樹脂之溶液以70℃加溫2週，測定加溫前後之Mn，以(加溫後之Mn)/(加溫前之Mn)作為分子量增加率，基於其分別對儲藏穩定性進行評價。 ＜剛成膜後之光澤性＞ 將各含氟樹脂之溶液蒸發乾燥、粉碎，分別獲得粉末狀之氟樹脂組合物。相對於所獲得之各粉末狀之氟樹脂組合物100質量份添加氧化鈦(Dupont公司製造，Ti-Pure(註冊商標)R960)67質量份、封端化異氰酸酯系硬化劑(Evonik公司製造，Vestagon(註冊商標)B1530)25質量份、作為硬化觸媒之二月桂酸二丁基錫之二甲苯溶液(10,000倍稀釋品)0.012質量份、作為除氣劑之安息香0.8質量份、表面調整劑(BYK-Chemie公司製造，BYK(註冊商標)-360P)2質量份，使用高速混合器(佑崎有限公司製造)混合10〜30分鐘左右而分別獲得粉末狀之混合物。 使用雙軸擠出機(Thermo Prism公司製造，16 mm擠出機)，於120℃之機筒設定溫度下，將粉末狀之混合物進行熔融混練而獲得顆粒。繼而，使用粉碎機(FRITSCH公司製造，高速旋轉粉碎機(rotor speed mill)P14)於常溫下將顆粒粉碎，藉由150目之篩進行分級而分別獲得平均粒徑約為40 μm之粉體塗料組合物。 使用各粉體塗料組合物，藉由靜電塗裝機(Onoda Cement公司製造，GX3600C)對經鉻酸鹽處理之鋁板之一面進行靜電塗裝，於200℃環境中保持20分鐘。然後，將其放置冷卻至室溫，獲得附有厚度55〜65 μm之塗膜(硬化膜)之鋁板。 使用光澤計(日本電色工業公司製造，PG-1M)，於形成塗膜後24小時後對塗膜之表面之20°光澤度進行測定。 ＜流動性＞ 將各含氟樹脂之溶液蒸發乾燥、粉碎而分別獲得粉末狀之氟樹脂組合物。使用錠劑成形機，於壓力20 MPa、10秒之條件下將粉末狀之氟樹脂組合物0.5 g成形為錠劑狀。 使用雙面膠帶將錠劑狀之氟樹脂組合物貼附於鋁板，於傾斜60度之狀態下以200℃加溫20分鐘，測定流動之距離。基於流動之距離，藉由以下基準對流動性進行評價。 ◎：流動距離為100 mm以上 ○：流動距離為60 mm以上且未達100 mm △：流動距離為30 mm以上且未達60 mm ×：流動距離未達30 mm ＜評價結果＞ 將以上評價試驗之結果示於第1表。再者，第1表中之括號內之數值表示相對於氟樹脂之含量(固形物成分)100質量份之各成分之含量(質量份)。 [表1]

如第1表所示，實施例之含氟樹脂之溶液之氯離子濃度均為50質量ppm以下，因此藉由使用其而獲得之塗料組合物所製作之塗膜之剛成膜後之塗膜之光澤性優異。又，實施例之含氟樹脂之溶液之儲藏穩定性亦均優異。 又，根據實施例1〜7之對比顯示，若氯離子濃度為3〜30質量ppm(實施例4及5)，則流動性亦優異。 另一方面，比較例1及比較例3之含氟樹脂之溶液之氯離子濃度超過50質量ppm，因此藉由使用其而獲得之塗料組合物所製作之塗膜之剛成膜後之塗膜之光澤性不充分。 此處，比較例1及比較例3中，使氟樹脂進行聚合時之水滑石之量相對於含胺基之化合物之量之比率處於1〜4之範圍外。因此認為，與水滑石一併作為不溶解成分而排出至含氟樹脂之溶液之系統外的氯離子量變少，氯離子濃度上升。 又，比較例2之含氟樹脂之溶液雖然氯離子濃度較低，但不含含胺基之化合物，因此儲藏穩定性較差(加溫後含氟樹脂之溶液凝膠化而無法測定氟樹脂之Mn)。又，於製作使用比較例2之含氟樹脂之溶液所獲得之塗料組合物時發生凝膠化，無法製造粉體組合物，而無法評價剛成膜後之光澤性。 再者，將於2016年01月14日提出申請之日本專利申請案2016-005279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 this specification, the term "monomer-based unit" is a collective term for an atomic group directly formed by polymerization of one monomer molecule, and an atomic group obtained by chemical conversion of a part of the atomic group. In addition, hereinafter, the monomer-based unit is also simply referred to as "unit". The content (mol %) of each unit of the fluoropolymer can be obtained by analyzing the fluoropolymer by nuclear magnetic resonance spectroscopy, and can also be estimated based on the added amount of each monomer. The "crosslinkable group" means a group that can form a crosslinked structure by reacting with a curing agent, or a group that can form a crosslinked structure by reacting with each other. In this specification, the number average molecular weight and the mass average molecular weight are the values obtained by gel permeation chromatography (GPC) method in terms of polystyrene. The number average molecular weight is also referred to as Mn. The so-called "hydrotalcite" means a layered double metal hydroxide represented by the following formula.

Wherein, x is 0.2~0.33, and m is 0~2. The so-called "(meth)acrylate" is the general term for acrylate and methacrylate. The term "ether-ester-based solvent" means a compound having both an ether bond and an ester bond in the molecule. Hereinafter, the fluorine-containing resin solution, the production method of the fluorine-containing resin solution, the coating composition, and the coated article of the present invention will be described in detail. [Fluorine-containing resin solution] The fluorine-containing resin solution of the present invention contains: a fluorine-containing resin containing a _{fluorine-containing polymer having units based on chlorotrifluoroethylene (CF 2} =CFCl, also referred to as "CTFE" hereinafter), Amino compounds and organic solvents, and the chloride ion concentration determined by the following chloride ion concentration measurement method is 50 mass ppm or less. Chloride ion concentration measurement method: The above-mentioned fluorine-containing resin solution and xylene are mixed to prepare a sample solution. After the obtained sample solution is mixed with water, the phase is separated into xylene phase and water phase, and the water phase is Recover and measure the chloride ion concentration in the recovered water by ion chromatography. In addition, the above-mentioned chloride ion concentration measurement method is also referred to as a "specific measurement method" below, and the chloride ion concentration means the chloride ion concentration obtained by a specific measurement method. The fluorine-containing resin solution of the present invention has excellent storage stability, and can form a coating film with excellent gloss just after film formation. The detailed reason is not clear, but it is believed to be roughly based on the following reasons. In the present invention, a fluororesin containing a fluoropolymer having CTFE-based units is used. In accordance with the method specifically described in Patent Document 1, the inventors used a solution containing a fluoropolymer containing CTFE-based units to produce a coating composition, and studied the coating film obtained using the coating composition Glossiness (refer to Comparative Example 1 described below). As a result, the inventors of the present invention found that the gloss of the coating film just after the film formation was reduced. Then, the inventors discovered that the chloride ion concentration of the fluorine-containing resin solution is closely related to the decrease in the gloss of the coating film just after the film is formed. Specifically, the inventors of the present invention have found that, as shown in the examples described below, if the chloride ion concentration is set to a specific value or less, a coating film with excellent gloss immediately after film formation can be obtained. Furthermore, the detailed reasons for the relationship between chloride ions and the gloss of the coating film are not clear, but it is believed that the gloss is deteriorated due to the following reasons: when the coating film is formed, components derived from acids (chloride ions derived from hydrogen chloride, etc.) ) It is locally present on the surface of the coating film and there is a difference in the curing speed between the surface of the coating film and the inside of the coating film; or the fluororesin gels before film formation during baking coating, and the melt fluidity becomes poor, and a uniform coating is not formed. membrane. Furthermore, the so-called "just after film formation" means within 24 hours from the production of the coating film. In addition, since the fluororesin solution of the present invention contains an amine group-containing compound, it is estimated that the fluororesin can stably exist in the solution. As a result, it is considered that the time-dependent thickening of the fluorine-containing resin solution is suppressed, and the storage stability of the fluorine-containing resin solution is excellent. Furthermore, Patent Document 1 discloses a specific aspect of using an amine group-containing compound and hydrotalcite to produce a solution containing a fluorine-containing resin having a fluorine-containing polymer having CTFE-based units. However, the present inventors discovered this aspect The chloride ion concentration in the sample is relatively high. The reason is not necessarily clear, but it is considered as follows. First, it is believed that the chloride ions contained in the fluororesin solution are mainly generated by the decomposition of CTFE that occurs during the polymerization of CTFE. In the presence of chloride ions, if there is an amine group-containing compound, hydrochloride is formed between the amine group-containing compound and the chloride ion. Moreover, if hydrotalcite is present in this case, chloride ions are also adsorbed by the hydrotalcite. That is, in the specific aspect of Patent Document 1, both the chloride ion and the amine group-containing compound to form a salt and the adsorption of the chloride ion to the hydrotalcite are performed. The hydrotalcite is separated from the fluoropolymer by filtration treatment or the like after polymerization. Therefore, the chloride ions adsorbed by the hydrotalcite are removed to the outside of the system. On the other hand, chloride ions that form salts with compounds containing amine groups still remain in the system. That is, the amount of chloride ions contained in the fluororesin solution is affected by the amount of the amine group-containing compound and hydrotalcite used. Specifically, the inventors found that when the amount of the amine-containing compound used is more than that of the hydrotalcite, a large amount of chloride ions that form a salt with the amine-containing compound remain in the system. As a result, The chloride ion concentration becomes higher, so the desired effect cannot be obtained. In the present invention, as explained in detail below, when manufacturing the fluororesin solution, the used mass of hydrotalcite relative to the used mass of the amine group-containing compound is set to a specific ratio, which is the removal of chloride ions outside the system It is controlled with the residual amount in the system, so it is believed that the chloride ion concentration of the fluorine-containing resin solution can be reduced, and the desired effect can be obtained as a result. The fluoropolymer in the present invention has CTFE-based units, and preferably further has units other than the above-mentioned units (hereinafter also referred to as other units). The other unit is preferably a unit based on a fluoroolefin other than CTFE, a unit based on a monomer having a crosslinkable group (hereinafter also referred to as "monomer 1"), or a unit based on a monomer that does not have a fluorine atom and a crosslinkable group. The unit of the monomer (hereinafter also referred to as "monomer 2") is more preferably a unit based on the monomer 1 or a unit based on the monomer 2. It is particularly preferable that the fluoropolymer has both the unit based on monomer 1 and the unit based on monomer 2. The number of fluorine atoms contained in fluoroolefins other than CTFE is preferably 2 or more, more preferably 2 to 6, and still more preferably 3 to 4. If the number of fluorine atoms is 2 or more, the obtained coating film has excellent weather resistance. Fluoroolefins other than CTFE are preferably CF ₂ =CF ₂ , CH ₂ =CF ₂ , or CH ₂ =CFCF ₃ , particularly _{preferably CF 2} =CF ₂ . Two or more types of fluoroolefins other than CTFE can also be used. Monomer 1 is a monomer having a crosslinkable group. The crosslinkable group is preferably a functional group having active hydrogen (a hydroxyl group, a carboxyl group, an amino group, etc.), or a hydrolyzable silyl group (alkoxysilyl group, etc.), an epoxy group, or an oxetanyl group. Monomer 1 is preferably a monomer represented by the formula CH ₂ =CX ¹ (CH ₂ ) _n1 -Q ¹ -R ¹ -Y ¹ . Wherein, in the formula, X ¹ is a hydrogen atom or a methyl group, n1 is 0 or 1, Q ¹ is a single bond, an etheric oxygen atom, -C(O)O- or -O(O)C-, and R ¹ is An alkylene having 2 to 20 carbons, an alkylene having 2 to 20 carbons containing an etheric oxygen atom, or an alkylene having 6 to 20 carbons having a ring structure, and Y ¹ is a crosslinkable group. X ^{1 is} preferably a hydrogen atom. n1 is preferably 0. Q ^{1 is} preferably an oxygen atom or -O(O)O-, preferably an oxygen atom. R 1 is preferably a linear alkylene group having ^{1 to 10 carbon atoms.} The carbon number of the alkylene group is more preferably 1 to 6, and still more preferably 2 to 4. Y ^{1 is} preferably a hydrolyzable silyl group, a hydroxyl group, a carboxyl group or an amino group, more preferably a hydroxyl group, a carboxyl group or an amino group, and still more preferably a hydroxyl group. Specific examples of monomer 1 include: hydroxyalkyl vinyl ether (2-hydroxyethyl vinyl ether, hydroxymethyl vinyl ether, 4-hydroxybutyl vinyl ether, etc.), hydroxyalkyl vinyl ether Ester, hydroxyalkyl allyl ether (hydroxyethyl allyl ether, etc.), hydroxyalkyl allyl ester, hydroxyalkyl (meth)acrylate (hydroxyethyl (meth)acrylate, etc.), etc. Preferably, the hydroxyalkyl group and the hydroxyallyl group in the hydroxyalkyl vinyl ester and the hydroxyalkyl allyl ester are respectively bonded to the carbon atom of the carbonyl group of the ester bond. Monomer 1 is preferably hydroxyalkyl vinyl ether or hydroxyalkyl allyl ether, and more preferably hydroxyalkyl vinyl ether in terms of excellent copolymerizability and excellent weather resistance of the formed coating film , Especially preferred is 4-hydroxybutyl vinyl ether. The monomer 1 can also use two or more types. Monomer 2 is a monomer that does not have a fluorine atom and a crosslinkable group. As the monomer 2, a monomer represented by the formula CH ₂ =CX ² (CH ₂ ) _n2- Q ² -R ² is preferred. Wherein, in the formula, X ² is a hydrogen atom or a methyl group, n2 is 0 or 1, Q ² is a single bond, an oxygen atom, -C(O)O- or -O(O)C-, and R ² is a carbon number An alkyl group having 2-20 carbon atoms, an alkyl group having an etheric oxygen atom having 2-20 carbon atoms, or an alkyl group having 6-20 carbon atoms having a ring structure. X ^{2 is} preferably a hydrogen atom. n2 is preferably 0. Q ^{2 is} preferably an oxygen atom or -O(O)C-, preferably an oxygen atom. R ^{2 is} preferably an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 6 to 20 carbon atoms having a ring structure, more preferably an alkyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 6 to 12 carbon atoms , Particularly preferably an alkyl group with 2 to 4 carbons, or a cycloalkyl group with 6 to 10 carbons. Specific examples of monomer 2 include: alkyl vinyl ether, cycloalkyl vinyl ether, alkyl vinyl ester, alkyl allyl ether, alkyl allyl ester, alkyl (meth)acrylate Base ester and so on. Preferably, the alkyl group in the alkyl vinyl ester and the alkyl allyl ester is bonded to the carbon atom of the carbonyl group of the ester bond. Monomer 2 is preferably alkyl vinyl ether or cycloalkyl vinyl ether, more preferably ethyl vinyl ether, cyclohexyl vinyl ether, or 2-ethylhexyl vinyl ether, because of the rigidity of fluororesin In terms of being relatively tall, soluble in organic solvents, easy to apply when applied to paints, and obtaining a harder coating film, cyclohexyl vinyl ether is particularly preferred. The monomer 2 can also use two or more types. The ratio of CTFE-based units in the fluoropolymer relative to all units of the fluoropolymer is preferably 40-60 mol%, more preferably 45-55 mol%. If the ratio is 40 mol% or more, the obtained coating film has excellent weather resistance. If the ratio is 60 mol% or less, the solubility in organic solvents or diluents is excellent. When the fluoropolymer has a unit based on monomer 1 and a unit based on monomer 2, the total ratio is preferably 40-60 mol% relative to all units of the fluoropolymer, and more Preferably, it is 45 to 55 mole%. Therefore, when the units other than the units based on CTFE are only the units based on monomer 1 and the units based on monomer 2, the ratio of the total of the units based on monomer 1 and the units based on monomer 2 is relative to that of fluorine-containing units. All units of the polymer are preferably 40-60 mol%, more preferably 45-55 mol%. In the case of having units based on monomer 1, the ratio relative to all units of the fluoropolymer is preferably 5-40 mol%, more preferably 8-35% mol%. If the ratio is 5 mol% or more, a sufficient amount of crosslinkable groups to obtain a coating film with higher hardness is introduced into the fluoropolymer. If the ratio is 40 mol% or less, even if it is a high solid content type, it is possible to maintain a sufficiently low viscosity as a fluorine-containing resin solution. In the case of having units based on monomer 2, the ratio relative to all units of the fluoropolymer is preferably more than 0 mol% and 45 mol% or less, more preferably 3 to 45 mol%, More preferably, it is 20 to 45 mol%. If this unit is provided, the hardness or flexibility of the obtained coating film can be adjusted appropriately. If the above-mentioned ratio is 45 mol% or less, it is easy to introduce a crosslinkable group in an amount sufficient to obtain a coating film with excellent weather resistance and high hardness in the fluoropolymer. In the case of CTFE-based units, monomer-based units and monomer-based units other than monomer-based units, the ratio of the units relative to all units of the fluoropolymer is preferably 20 mol% or less, more preferably 10 mol% or less. The Mn of the fluoropolymer is preferably 3,000 to 50,000, more preferably 5,000 to 30,000. If the Mn of the fluoropolymer is more than the above lower limit, the coating film has excellent water resistance, salt water resistance, and the like. If the Mn of the fluoropolymer is less than the above upper limit, the surface smoothness of the coating film is excellent. Furthermore, there is substantially no hydrotalcite in the fluorine-containing resin solution of the present invention. The term "substantially free of hydrotalcite" means that the amount of hydrotalcite contained in the fluorine-containing grease solution of the present invention is less than 0.1% by mass, and is generally preferably 0.01% by mass or less. The lower limit of the amount of hydrotalcite is 0% by mass. The amine group-containing compound in the present invention is not particularly limited as long as it is an amine group-containing compound. Furthermore, in this specification, the above-mentioned "amine group-containing compound" also includes the form of forming a salt with hydrogen chloride (HCl). That is, the above-mentioned "amine group-containing compound" also includes the hydrochloride of the amine group-containing compound. Examples of the amino group include a primary amino group (-NH ₂ ), a secondary amino group, and a tertiary amino group. The secondary amino group is a mono-substituted amino group represented by the ^{formula -NHR N} (R ^{N is a monovalent substituent). Specific examples of R N} include alkyl, aryl, acetyl, and benzyl , Benzenesulfonyl, tertiary butoxycarbonyl, etc. Specific examples of secondary amino groups include: methylamino groups, ethylamino groups, propylamino groups, isopropylamino groups, and other secondary amino groups where R is an alkyl group; or phenylamino groups, naphthalene groups, etc. Amino group, etc. R is a secondary amino group of an aryl group, etc. In addition, the ^{hydrogen atom in R N} may be further substituted with an acetyl group, a benzyl group, a benzenesulfonyl group, a tertiary butoxycarbonyl group, and the like. The tertiary amino group is a disubstituted amino group represented by the formula -NR ^N1 R ^N2 (R ^N1 and R ^N2 are monovalent substituents), and specific examples of ^{R N1} and R ^{N2 are} the same as ^{R N.} Specific examples of tertiary amino groups include dimethylamino, diethylamino, dibutylamino, ethylmethylamino, diphenylamino, methylphenylamino, and the like. As an amino group, an alicyclic amino group can also be mentioned. The alicyclic amino group is an alicyclic group containing at least one nitrogen atom in the ring. The alicyclic amino group is preferably a 5- to 7-membered alicyclic amino group such as pyrrolidinyl, piperidinyl, piperidine, and azepanyl, and particularly preferably a 6-membered alicyclic group Formula amino (piperidinyl). In addition, the hydrogen atom in the alicyclic amino group may be further substituted with a substituent (alkyl group, aryl group, etc.). The 6-membered alicyclic amine group is preferably piperidinyl or substituted piperidinyl, more preferably substituted piperidinyl, more preferably tetra-substituted piperidinyl, and particularly preferably 2, 2,6,6-Tetra-substituted piperidinyl. Two or more types of amine group-containing compounds can also be used. The amine group-containing compound is preferably a compound represented by the following formula (a compound having a 2,2,6,6-tetrasubstituted piperidinyl group). [化1]

R ^{11 to R 14} are each independently an alkyl group having 1 to 18 carbon atoms (methyl, ethyl, propyl, dodecyl, stearyl, etc.), cycloalkyl (cyclopentyl, cyclohexyl, etc.), Substituted alkyl (2-hydroxyethyl, 2-methoxycarbonylethyl, 3-hydroxypropyl, etc.), aryl (phenyl, naphthyl, etc.) or aralkyl (phenethyl, benzyl, etc.) , R ¹¹ and R ¹² , or R ¹³ and R ¹⁴ can form an aliphatic ring with 3-6 carbons. As R ^{11 to} R ¹⁴ , in terms of price and availability, an alkyl group having 1 to 18 carbon atoms is preferred, and a methyl group is particularly preferred. R ¹⁵ is a hydrogen atom, alkyl (methyl, ethyl, propyl, butyl, dodecyl, stearyl, etc.), substituted alkyl (2-hydroxyethyl, 2-methoxycarbonylethyl, etc.) , 2-acetoxyethyl, 2-(3-methoxycarbonylpropionyloxy)ethyl, 3-hydroxypropyl, etc.), aryl (phenyl, naphthyl, hydroxyphenyl, etc.), Aralkyl (phenethyl, benzyl, hydroxyphenylalkyl, etc.) or cycloalkyl (cyclohexyl, etc.). R ¹⁶ is a hydrogen atom, hydroxyl, alkyl (methyl, ethyl, propyl, butyl, dodecyl, stearyl, etc.), substituted alkyl (2-hydroxyethyl, 2-methoxycarbonyl, etc.) Ethyl, 2-acetoxyethyl, 2-(3-methoxycarbonylpropionyloxy)ethyl, 3-hydroxypropyl, etc.), aryl (phenyl, naphthyl, etc.), aralkyl Group (phenethyl, benzyl, etc.), ester bond-containing groups (acetoxy, propoxy, butoxy, lauryloxy, substituted alkylcarbonyloxy, benzyloxy, Substituted benzyloxy group, etc.), amino group-containing groups (alkoxycarbonylamino group, N-monoalkylamine methanoylamino group, N,N-dialkylamine methanoylamino group, etc.) or Contains 2,2,6,6-tetrasubstituted piperidinyl groups. R ¹⁶ may combine two or more of these groups. Specific examples of the amine group-containing compound include: 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-pentamethylpiperidine, 4-hydroxy-2,2 ,6,6-Tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 1-ethyl-2,2,6,6-tetramethylpiperidine, 1-ethyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-butyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-dodecane Alkyl-2,2,6,6-tetramethylpiperidine, 1-phenyl-2,2,6,6-tetramethylpiperidine, 1-(2-hydroxyethyl)-2,2, 6,6-Tetramethylpiperidine, 1-(6-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-acetoxy-2,2,6 ,6-Tetramethylpiperidine, 4-acetoxy-1,2,2,6,6-pentamethylpiperidine, 1-(2-acetoxyethyl)-4-acetoxy Base-2,2,6,6-tetramethylpiperidine, 1-(2-benzyloxyethyl)-4-benzyloxy-2,2,6,6-tetramethylpiperidine Pyridine, 4-ethyl-2,2,6,6-tetramethylpiperidine, 4-ethyl-1,2,2,6,6-pentamethylpiperidine, 4-butyl-2,2 ,6,6-Tetramethylpiperidine, 4-octyl-2,2,6,6-tetramethylpiperidine, 4-dodecyl-2,2,6,6-tetramethylpiperidine , 4-stearyl-2,2,6,6-tetramethylpiperidine, 4-stearyl-1,2,2,6,6-pentamethylpiperidine, methyl sebacate 1, 2,2,6,6-pentamethyl-4-piperidinyl ester, bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, etc. As R ¹⁶ is a 2,2,6,6-tetrasubstituted piperidinyl-containing group-containing amine-containing compound, for example, 2,2,6,6-tetramethylpiperidine (4-hydroxyl -2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, 1-(2-hydroxyethyl)-4-hydroxy-2 , 2,6,6-tetramethylpiperidine, 1-(2-hydroxyethyl)-2,2,6,6-tetramethylpiperidine, etc.) and polybasic acids (succinic acid, adipic acid, decanoic acid, etc.) Diacid, azelaic acid, decane-1,10-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, malonic acid, substituted malonic acid, etc.) The obtained amino group-containing compound containing two or more 2,2,6,6-tetramethylpiperidinyl groups in one molecule is specifically exemplified by compounds represented by the following formulas. Wherein, n3 is an integer of 1-20. [化2]

The content of the amine group-containing compound relative to 100 parts by mass of the above-mentioned fluororesin is preferably 0.1 to 2.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, and still more preferably 0.5 to 1.5 parts by mass. If the content is 0.1 parts by mass or more, the fluorine-containing resin solution becomes less likely to gel during or after the polymerization of the monomer components, and the storage stability of the fluorine-containing resin solution is more excellent. Moreover, if the content is 2.0 parts by mass or less, the discoloration (such as yellowing or clouding) of the solution of the fluororesin solution in storage or the increase in the molecular weight of the fluoropolymer is further suppressed. The storage stability of the solution is more excellent. The organic solvent in the present invention is not particularly limited as long as it is an organic solvent that can dissolve the fluororesin. It is preferably selected from aromatic hydrocarbon solvents, ketone solvents, ester solvents, alcohol solvents, and ether ester solvents. One or more organic solvents in the group. The aromatic hydrocarbon solvent is preferably toluene, xylene, ethylbenzene, aromatic naphtha, tetralin, or turpentine. As the aromatic hydrocarbon solvent, commercially available products can be used, and Solvesso (registered trademark) #100 (manufactured by Exxon Chemical Co., Ltd.), Solvesso (registered trademark) #150 (manufactured by Exxon Chemical Co., Ltd.), etc. can be used. The ketone solvent is preferably acetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, diisobutyl ketone, cyclohexanone, or isophorone. The ester solvent is preferably methyl acetate, ethyl acetate, n-propyl acetate, isobutyl acetate, or t-butyl acetate. The alcohol-based solvent is preferably an alcohol having a carbon number of 4 or less, preferably ethanol, tert-butanol, or isopropanol. The ether ester solvent is preferably 3-ethoxy ethyl propionate, propylene glycol monomethyl ether acetate, or methoxy butyl acetate. Two or more organic solvents can also be used. In addition, the organic solvent may be the same as the organic solvent used as the polymerization solvent, or may be a different organic solvent. From the viewpoint that the solubility of the fluororesin becomes good, the content of the organic solvent is preferably contained so that the solid content concentration in the solution of the fluororesin becomes 40 to 80% by mass. The solution of the fluorine-containing resin of the present invention may contain components other than the above (for example, general-purpose resin components such as acrylic resins or polyester resins) within the range where the effects of the present invention can be sufficiently exhibited. The fluorine-containing resin solution of the present invention has a chloride ion concentration of 50 mass ppm or less determined by a specific measurement method. The chloride ion concentration is more preferably 40 mass ppm or less, still more preferably 30 mass ppm or less, and particularly preferably 10 mass ppm or less. The lower limit is preferably 1 ppm by mass, and particularly preferably 3 ppm by mass. If the chloride ion concentration is 50 mass ppm or less, the coating film obtained by using the fluorine-containing resin solution of the present invention has excellent gloss just after film formation. On the other hand, if the chloride ion concentration exceeds 50 mass ppm, the gloss just after the film formation becomes insufficient. In particular, if the chloride ion concentration is 3-30 mass ppm, the fluidity of the coating composition obtained by using the fluorine-containing resin solution is also excellent. If the fluidity of the coating composition obtained by using the fluorine-containing resin solution is excellent, when the powder composition coated on the substrate is melted to form a coating film (cured film), the fluidity of the coating composition is improved. Therefore, it is preferable in terms of obtaining a smooth and uniform coating film (cured film). If the chloride ion concentration is 30 mass ppm or less, the generation of hydrogen chloride caused by the powdering (desolventizing) of the fluorine-containing resin solution or the heat during baking and coating can be suppressed. It is estimated that the gelation of the fluororesin contained in the coating composition is suppressed by this, and the fluidity of the coating composition is improved. In the present invention, the chloride ion concentration is measured by a specific measuring method, that is, the fluorine-containing resin solution of the present invention is mixed with xylene to prepare a sample solution, and the obtained sample solution is mixed with water , The phases are separated into xylene phase and water phase, the water phase is recovered and the chloride ion concentration in the recovered water is measured by ion chromatography. In more detail, the chloride ion concentration is measured as follows. First, the solution of the fluorine-containing resin of the present invention and xylene are mixed and stirred to obtain a sample solution. Furthermore, the amount of the fluorine-containing resin solution was set to 0.5 g relative to the amount of xylene 5 mL. Then, the sample solution and pure water are mixed and stirred to obtain a mixed solution. In addition, the amount of pure water is set to 3 mL relative to the added amount of 4.9 g of the sample solution. Then, the mixed liquid is centrifuged to separate the mixed liquid phase into an aqueous phase and a xylene phase, and the xylene phase is removed to obtain a separated liquid. Furthermore, the separated liquid is centrifuged to phase-separate the residual xylene (xylene phase) and water (aqueous phase), the xylene phase is removed, and the water phase is recovered. Then, a measurement solution diluted with pure water added to the recovered water (aqueous phase) was prepared, and the chloride ion concentration was measured by ion chromatography. In addition, a well-known centrifugal separation device (specifically, a device in accordance with the trade name "Desktop Cooling Centrifuge 5500" manufactured by Kubota Manufacturing Co., Ltd.) is used in any centrifugal separation, and the centrifugal separation conditions are set at 12000 rpm. minute. In addition, the measurement by ion chromatography is performed by using an ion chromatograph ICS-1500 (trade name, manufactured by Dionex Corporation), for example. The specific measurement conditions of the chloride ion concentration measured by ion chromatography are as follows. Further, with respect to the peak area of standard solution of a known concentration of a detectable amount ratio measurement, conversion and chloride ions (Cl ^-) of the amount. Moreover, chloride ions (Cl ^-) The limit of quantification of 0.6 ppm or less. <Conditions of ion chromatography> Device: ICS-1500 suppressor manufactured by Dionex Company analysis column: Dionex IonPac AS14 inner diameter 4.0 mm × length 50 mm Guard column: Dionex IonPac AG14 inner diameter 4.0 mm × length 250 mm Liquid: 3.5 mmol Na ₂ CO ₃ , 1.0 mmol NaHCO ₃ Flow rate: 1.5 ml/min [Manufacturing method of fluorine-containing resin solution] The manufacturing method of the fluorine-containing resin solution of the present invention is the following method: in an amine-containing compound And the presence of hydrotalcite, the monomer components containing CTFE are polymerized in an organic solvent to obtain a fluoropolymer-containing mixed solution, and then the fluorine-containing polymer-containing mixed solution is removed from the above-mentioned hydrotalcite. Dissolve the components to produce a fluorine-containing resin solution. In addition, the ratio of the amount of hydrotalcite to the amount of the amine group-containing compound (the amount of hydrotalcite/the amount of the amine group-containing compound) at the time point when the monomer components start to polymerize is 1 to 4. Furthermore, the chloride ion concentration determined by a specific measuring method is preferably 50 mass ppm or less. According to the method for producing a fluorine-containing resin solution of the present invention, a fluorine-containing resin solution with excellent storage stability can be obtained, and a coating film with excellent gloss just after film formation can be formed. Hereinafter, the step of performing polymerization is referred to as a polymerization step, and the step of performing filtering is referred to as a filtering step, and each step is described in detail. The monomer components in the polymerization step are polymerized by the so-called solution polymerization method. The order of addition of each component in the polymerization system can be appropriately selected. As the monomer component, in addition to CTFE, monomer 1 and monomer 2 may also be used. The details of the amine group-containing compound, CTFE, and fluororesin in the polymerization step are as described above, and the description is omitted. As the organic solvent, the same organic solvent as the organic solvent described in the section of the fluorine-containing resin solution can be cited. The organic solvent in the polymerization step may be the same as or different from the organic solvent contained in the fluorine-containing resin solution of the present invention. _{The hydrotalcite in the polymerization step is preferably Mg 6} Al ₂ (OH) ₁₆ CO ₃ ·4H ₂ O (in the above formula representing hydrotalcite in terms of excellent adsorption of chloride ions and easy availability) , X=0.25, m=0.5), or Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ ·3.5H ₂ O (in the above formula for hydrotalcite, x=0.308, m=0.538). Two or more types of hydrotalcite can also be used. The particle size of the hydrotalcite is preferably 5 to 500 μm, more preferably 5 to 110 μm. If the particle size of the hydrotalcite is 5 μm or more, it becomes easy to remove by filtration. If the particle size of the hydrotalcite is 500 μm or less, the surface area per unit mass is larger, and the effect obtained by the hydrotalcite is further exerted. The particle size of hydrotalcite is measured in accordance with JIS K 0069 "Test Method for Screening of Chemical Products". In the polymerization step, it is preferable to polymerize the monomer components by the action of a polymerization initiator. As the polymerization initiator, azo initiators (2,2'-azobisisobutyronitrile, 2,2'-azobiscyclohexanonitrile, 2,2'-azobis(2, 4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), etc.), peroxide initiator (ketone peroxide (cyclohexanone peroxide, etc.), peroxide Hydrogen (tertiary butyl hydroperoxide, etc.), diacyl peroxide (benzyl peroxide, etc.), dialkyl peroxide (di-tertiary butyl peroxide, etc.), peroxyketal (2,2 -Di-(tertiary butylperoxy)butane, etc.), alkyl peroxy ester (tert-butyl peroxypivalate, etc.), peroxycarbonate (diisopropyl peroxydicarbonate, etc.) }. At the point of time when the polymerization starts in the polymerization step, the ratio of the mass of the hydrotalcite to the mass of the amine-containing compound (the mass of the hydrotalcite/the mass of the amine-containing compound) is 1~4, preferably 1.0~3 , Preferably 1.0~2. If the ratio is 1 or more, as described in the fluorine-containing resin solution, the chloride ion concentration can be adjusted to a specific range, and the gloss of the coating film immediately after the film formation is excellent. In addition, if the ratio is 4 or less, it is easy to suppress clogging of the filter material when removing insoluble components in the filtration step. The amount of the amine group-containing compound relative to 100 parts by mass of the monomer components is preferably 0.1 to 2.0 parts by mass, more preferably 0.5 to 2.0 parts by mass, and still more preferably 0.5 to 1.5 parts by mass. If the amount is 0.1 parts by mass or more, the fluorine-containing resin solution becomes less likely to gel during or after the polymerization of the monomer components, and the storage stability of the fluorine-containing resin solution is more excellent. In addition, if the amount is 2.0 parts by mass or less, the discoloration of the solution of the fluororesin solution in storage (such as yellowing or white turbidity) or the increase in the molecular weight of the fluororesin is further suppressed, and the solution of the fluororesin The storage stability is more excellent. The amount of CTFE in the monomer components relative to the total monomer components is preferably 40-60 mol%, more preferably 45-55 mol%. If the amount of CTFE is 40 mol% or more, the resulting coating film has excellent weather resistance. If the amount of CTFE is 60 mol% or less, the solubility in organic solvents or diluents is excellent. When the monomer 1 and the monomer 2 are contained as monomer components, the total amount thereof is preferably 40-60 mol%, and more preferably 45-55 mol% with respect to all monomer components. Therefore, when the monomer components other than CTFE are only monomer 1 and monomer 2, the total amount of monomer 1 and monomer 2 relative to the total monomer components is preferably 40-60 mol%, and more Preferably, it is 45 to 55 mole%. The amount of monomer 1 in the monomer components is preferably 5-40 mol%, more preferably 8-35% mol% with respect to the total monomer components. If the amount is 5 mol% or more, a crosslinkable group in an amount sufficient to obtain a coating film with high hardness is introduced into the fluoropolymer. If the amount is 40 mol% or less, even if it is a high solid content type, it can be used as a fluorine-containing resin solution to maintain a low viscosity. The amount of monomer 2 in the monomer components is preferably more than 0 mol% and 45 mol% or less, more preferably 3 to 45 mol%, and still more preferably 20 to 45 mol% relative to the total monomer components. Mol%. If monomer 2 is used, the hardness or flexibility of the obtained coating film can be adjusted appropriately. If the amount is 45 mol% or less, it is easy to introduce a crosslinkable group in an amount sufficient to obtain a coating film with excellent weather resistance and high hardness in the fluoropolymer. In the case of monomer components containing CTFE, monomer 1 and monomer other than monomer 2, the amount of the monomer relative to the total monomer components is preferably 20 mol% or less, more preferably 10 mol% %the following. In the filtration step of the present invention, the hydrotalcite (ie, the insoluble component derived from the hydrotalcite) that is an insoluble component insoluble in an organic solvent and adsorbed with chloride ions generated in the polymerization step is removed. The removal is performed by solid-liquid separation treatment such as filtration. The fluorine-containing resin solution obtained by the above-mentioned production method of the present invention preferably has a chloride ion concentration of 50 mass ppm or less as measured by a specific measurement method. The more preferable range and effect of the chloride ion concentration are as described in the fluorine-containing resin solution, so the description is omitted. In addition, the fluorine-containing resin solution obtained by the production method of the present invention is preferably substantially free of hydrotalcite. The term "substantially free of hydrotalcite" means that the amount of hydrotalcite contained in the fluorine-containing grease solution is less than 0.1% by mass, and is generally preferably 0.01% by mass or less. The lower limit of the amount of hydrotalcite is 0% by mass. In the manufacturing method of the present invention, it is also possible to add hydrotalcite to the mixed solution containing the fluoropolymer after the polymerization step and before the filtration step. Furthermore, after the hydrotalcite is added and before the filtration step, a stirring treatment may also be performed. Thereby, the chloride ion concentration can be further reduced, and the obtained coating film has more excellent gloss just after film formation. In addition, the storage stability of the fluorine-containing resin solution also tends to be more excellent. The amount of hydrotalcite added is preferably 0.1 to 3.0 parts by mass, more preferably 0.5 to 2.0 parts by mass relative to 100 parts by mass of the produced fluoropolymer. If the amount is within the above-mentioned range, the above-mentioned effects are further exhibited. [Coating composition] The coating composition of the present invention is a coating composition obtained by using the fluorine-containing resin solution of the present invention. The coating composition of the present invention may be liquid or powder (so-called powder coating composition). The liquid coating composition is a coating composition containing the above-mentioned fluorine-containing resin solution, and preferably contains a hardener in addition to the fluorine-containing resin solution. Examples of the curing agent include isocyanate-based curing agents, blocked isocyanate-based curing agents, or amino resins. The isocyanate-based hardener is preferably a non-yellow variant cyanate (for example, hexamethylene diisocyanate, isophorone diisocyanate, etc.). The blocked isocyanate-based curing agent is preferably a curing agent obtained by blocking the isocyanate group of the isocyanate-based curing agent by caprolactam, isophorone, β-diketone, or the like. Amino resin series amines (melamine, melamine, urea, etc.) and aldehydes (formaldehyde, etc.) reaction products (methylol melamine, etc.) or derivatives (alkyl etherified methylol melamine, etc.). Examples of amine-based resins include melamine resins, melamine resins, urea resins, sulfonamide resins, and aniline resins. The content of the hardener is preferably 1-100 parts by mass, more preferably 1-50 parts by mass relative to 100 parts by mass of the fluororesin in the coating composition. If the curing agent is 1 part by mass or more, the solvent resistance and hardness of the coating film are excellent. If it is 100 parts by mass or less, the processability and impact resistance of the coating film are excellent. The liquid coating composition may further contain components other than the above. Examples of such components include colorants, resins other than the above-mentioned fluororesins, silane coupling agents, ultraviolet absorbers, curing catalysts, and the like. In addition, the coating composition of the present invention may also be a coating composition containing a fluororesin composition obtained by removing the above-mentioned organic solvent from the solution of the fluororesin of the present invention. The coating composition may also be a liquid coating composition obtained by dissolving the fluororesin composition in a solvent or dispersing in a dispersion medium. Preferably, it is a coating composition containing a fluororesin composition that does not contain a liquid medium such as the above-mentioned organic solvent. As a coating composition containing a fluororesin composition containing no liquid medium, a powder coating composition (so-called powder coating composition) is preferred. The powdery coating composition contains a fluorine resin composition obtained by removing the above-mentioned organic solvent from the fluorine-containing resin solution of the present invention. The powdered fluororesin composition can be produced by subjecting the fluororesin composition of the present invention to known treatments such as drying treatment and pulverization treatment. The powder coating composition preferably contains a hardener in addition to the above-mentioned fluororesin composition. Regarding the curing agent, it is the same as the above-mentioned liquid coating composition, and the description is omitted. In addition, the powdered coating composition may further contain components other than the above. As such a component, it is the same as the liquid coating composition mentioned above, and description is abbreviate|omitted. [Coated Article] The coated article of the present invention has a substrate and a coating film formed on the substrate by the coating composition. Examples of coating methods include spray coating, air spray coating, brush coating, dipping, electrostatic coating, roll coating, and flow coating. The coating film may also be a film (melted film) obtained by applying a well-known melting process after coating on a substrate. As the material of the substrate, inorganic materials, organic materials, organic-inorganic composite materials, etc. can be cited. Examples of inorganic substances include concrete, natural stone, glass, metals (iron, stainless steel, aluminum, copper, brass, titanium, etc.). Examples of organic substances include plastics, rubber, adhesives, wood, and the like. Examples of organic-inorganic composite materials include fiber-reinforced plastics, resin-reinforced concrete, and fiber-reinforced concrete. The shape, size, etc. of the substrate are not particularly limited. The application of the coated article of the present invention includes: transportation parts (cars, trams, airplanes, etc.), civil engineering components (bridge components, iron towers, etc.), industrial parts (waterproof material sheets, tanks, pipes, etc.) , Building components (building exteriors, doors, windows and doors components, monuments, poles, etc.), road components (road central separation belts, guard rails, sound insulation walls, etc.), communication components, electrical components, electronic components, solar Surface sheets for battery modules, back sheets for solar battery modules, etc. Examples Hereinafter, the present invention will be described in detail with examples. However, the present invention is not limited to these embodiments. The blending amount of each component in the table described below represents the quality standard. The solid content concentration of the fluororesin solution is determined by measuring the heating residue in accordance with JIS K 5601-1-2 (established in 2009). The Mn of the fluororesin contained in the fluororesin solution was measured by GPC (manufactured by Tosoh Corporation, HLC-8220). Tetrahydrofuran was used as a developing solvent, and polystyrene was used as a standard substance. [Fluorine-containing resin solution] The fluorine-containing resin solutions of the Examples and Comparative Examples were prepared in the following manner. <Preparation of the fluorine-containing resin solution of Example 1> In a 2500 mL stainless steel pressure-resistant reactor equipped with a stirrer, 7.32 g of an amine-containing compound (manufactured by BASF, trade name "TINUVIN292", decanoate Diacid bis(1,2,2,6,6-pentamethyl-4-piperidinyl) ester and methyl sebacate 1,2,2,6,6-pentamethyl-4-piperidinyl ester (Mass ratio 3: 1)), 7.32 g of hydrotalcite (manufactured by Kyowa Chemical Industry Co., Ltd., trade name "KW500", particle size: below 45 μm: 38%, 45~7 μm: 35%, 75~106 μm: 21%, 106~500 μm: 6%), 746 g of xylene, 153 g of 4-hydroxybutyl vinyl ether, 601 g of cyclohexyl vinyl ether, degassed by nitrogen Remove dissolved oxygen in the solution. Furthermore, 701 g of CTFE was introduced into the above-mentioned reactor, the temperature was gradually raised, and 4.1 g of tert-butyl peroxypivalate (polymerization initiator) was intermittently added at the time point when the temperature reached 65°C. polymerization. After 24 hours, the reactor was water-cooled to stop the reaction. After cooling the reaction liquid to room temperature, remove the unreacted monomers, remove the insoluble components of the obtained reaction liquid by filtering with diatomaceous earth as a filter material, and then add an appropriate amount of xylene to obtain a solid content concentration of 60.0% The fluorine-containing resin solution of Example 1. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solution of Example 1 is 15,500. <Preparation of the fluorine-containing resin solution of Example 2> Polymerization was carried out in the same manner as the preparation of the fluorine-containing resin solution of Example 1. Hydrotalcite KW500 was further added to the obtained reaction solution, and after stirring for 1 hour, The insoluble components were removed by filtration using diatomaceous earth as a filter material, and an appropriate amount of xylene was added to obtain the fluororesin solution of Example 2 with a solid content of 60.0%. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solution of Example 2 is 15,500. <Preparation of fluorine-containing resin solutions of Examples 3 to 5 and Comparative Example 1> The amount of at least one of the amine group-containing compound and hydrotalcite added during polymerization was changed to the amount described in Table 1. Otherwise, the same operation as the preparation of the fluorine-containing resin solution of Example 1 was performed to obtain the fluorine-containing resin solutions of Examples 3 to 5 and Comparative Example 1. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solutions of Examples 3 to 5 and Comparative Example 1 were 15100, 14900, 14800, and 15400, respectively. <Examples 6-7> The amine-containing compound added during polymerization was changed from TINUVIN292 to TINUVIN770DF (trade name, manufactured by BASF, sebacic acid bis(2,2,6,6-tetramethyl-4-piperidine) (Pyridinyl) ester) or diethanolamine, and the addition amount of the amine group-containing compound and hydrotalcite was set to the amount described in Table 1. Other than that, the same operation as the preparation of the fluorine-containing solution of Example 1 was carried out , To obtain the fluorine-containing resin solution of Examples 6-7. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solutions of Examples 6 to 7 were 15000 and 14900, respectively. In addition, the content of hydrotalcite in the fluorine-containing resin solution obtained in each of the above examples is 0.01% by mass or less. <Preparation of the fluorine-containing resin solution of Comparative Example 2> Except that the amine group-containing compound was not added during polymerization, the same operation as the preparation of the fluorine-containing resin solution of Example 1 was performed to obtain the comparative example 2 Fluorine resin solution. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solution of Comparative Example 2 was 16,400. <Preparation of the fluorine-containing resin solution of Comparative Example 3> The addition amount of the amine group-containing compound added during the polymerization was changed to the amount described in Table 1, and the hydrotalcite was not added during the polymerization. Otherwise, proceed The same operation as the preparation of the fluorine-containing resin solution of Example 2 was performed to obtain the fluorine-containing resin solution of Comparative Example 3. Furthermore, the Mn of the fluoropolymer contained in the fluororesin solution of Comparative Example 3 was 15,600. <Chloride ion concentration> The chloride ion concentration of each fluororesin solution was measured by the following procedure. Put 0.5 g of each fluororesin solution and 5 mL of xylene into a PP (polypropylene) tube, shake by hand for 1 minute to obtain a sample solution in which the fluororesin solution is completely dissolved in xylene. Then, 3 mL of pure water was added to the sample solution and vigorously shaken by hand to obtain a mixed solution. Then, the mixed solution was centrifuged to separate the phases into water and xylene, and then the xylene phase (upper layer) was removed from the mixed solution using a micropipette. Furthermore, the mixed liquid from which the xylene phase was removed was centrifuged to separate residual xylene (xylene phase) and water (aqueous phase). Any centrifugal separation was performed using a centrifugal separation device (trade name "table-top cooling centrifuge 5500", manufactured by Kubota Corporation) at 12000 rpm for 5 minutes. Next, a measurement solution obtained by diluting the separated and recovered water (aqueous layer) 5 times or 10 times with pure water is prepared, and the chloride ion concentration of the measurement solution is measured by ion chromatography. The measurement by ion chromatography was performed using an ion chromatograph ICS-3000 (trade name, manufactured by Thermo Fisher). The measurement conditions by ion chromatography are as follows. Specifically, with respect to the peak area of a standard solution of known concentration of a detectable amount ratio measurement, conversion and chloride ions (Cl ^-) of the amount. Furthermore, the limit of quantification chlorine ion (Cl ^-) count of 0.6 ppm or less. (Ion chromatography conditions) Device: ICS-1500 suppressor manufactured by Dionex Analytical column: Dionex IonPac AS14 inner diameter 4.0 mm × length 50 mm Guard column: Dionex IonPac AG14 inner diameter 4.0 mm × length 250 mm : 3.5 mmol Na ₂ CO ₃ , 1.0 mmol NaHCO ₃ Flow rate: 1.5 mL/min The measurement results of the chloride ion concentration above are summarized and shown in Table 1. [Evaluation test] The following evaluation test was carried out using each fluororesin solution. <Storage stability> The solution of each fluororesin was heated at 70°C for 2 weeks, the Mn before and after heating was measured, and (Mn after heating)/(Mn before heating) was used as the molecular weight increase rate, based on it The storage stability was evaluated separately. <Glossiness immediately after film formation> Each fluororesin solution was evaporated to dryness and pulverized to obtain powdery fluororesin compositions. With respect to 100 parts by mass of each obtained powdered fluororesin composition, 67 parts by mass of titanium oxide (manufactured by Dupont, Ti-Pure (registered trademark) R960) and a blocked isocyanate-based hardener (manufactured by Evonik, Vestagon) are added. (Registered trademark) B1530) 25 parts by mass, 0.012 parts by mass of dibutyltin dilaurate in xylene solution (10,000 times dilution) as a hardening catalyst, 0.8 parts by mass of benzoin as a degassing agent, surface conditioner (BYK- 2 parts by mass of BYK (registered trademark)-360P) manufactured by Chemie, mixed with a high-speed mixer (manufactured by Yusaki Co., Ltd.) for about 10 to 30 minutes to obtain a powdery mixture. Using a biaxial extruder (manufactured by Thermo Prism, 16 mm extruder), the powdery mixture was melted and kneaded at a barrel set temperature of 120°C to obtain pellets. Then, use a grinder (manufactured by FRITSCH, rotor speed mill P14) at room temperature to pulverize the particles, and classify them with a 150-mesh sieve to obtain powder coatings with an average particle size of about 40 μm. combination. Using each powder coating composition, electrostatic coating was performed on one side of the chromate-treated aluminum plate with an electrostatic coating machine (manufactured by Onoda Cement Co., Ltd., GX3600C), and kept at 200°C for 20 minutes. Then, it was left to cool to room temperature to obtain an aluminum plate with a coating film (cured film) with a thickness of 55 to 65 μm. Using a gloss meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., PG-1M), the 20° gloss of the surface of the coating film was measured 24 hours after the coating film was formed. <Fluidity> Each fluororesin solution is evaporated, dried, and pulverized to obtain powdery fluororesin compositions. Using a tablet molding machine, 0.5 g of the powdered fluororesin composition was molded into a tablet under the conditions of a pressure of 20 MPa and 10 seconds. Attach the tablet-like fluororesin composition to the aluminum plate using a double-sided tape, and heat it at 200°C for 20 minutes in a state of inclination of 60 degrees, and measure the flow distance. Based on the distance of the flow, the fluidity is evaluated based on the following benchmarks. ◎: The flow distance is more than 100 mm ○: The flow distance is more than 60 mm and less than 100 mm △: The flow distance is more than 30 mm and less than 60 mm ×: The flow distance is less than 30 mm <Evaluation results> The above evaluation test The results are shown in Table 1. In addition, the values in parentheses in Table 1 indicate the content (parts by mass) of each component relative to 100 parts by mass of the content (solid content) of the fluororesin. [Table 1]

As shown in Table 1, the chloride ion concentration of the fluorine-containing resin solution of the examples is below 50 mass ppm, so the coating film produced by the coating composition obtained by using it is the coating film just after film formation The gloss is excellent. In addition, the storage stability of the fluorine-containing resin solutions of the examples is also excellent. In addition, a comparison of Examples 1 to 7 shows that if the chloride ion concentration is 3 to 30 mass ppm (Examples 4 and 5), the fluidity is also excellent. On the other hand, the chloride ion concentration of the fluorine-containing resin solution of Comparative Example 1 and Comparative Example 3 exceeds 50 mass ppm, so the coating film produced by the coating composition obtained by using it is the coating film immediately after film formation The gloss is insufficient. Here, in Comparative Example 1 and Comparative Example 3, the ratio of the amount of hydrotalcite to the amount of the amine group-containing compound when the fluororesin is polymerized is outside the range of 1 to 4. Therefore, it is considered that the amount of chloride ions discharged out of the system of the fluororesin solution as an insoluble component together with the hydrotalcite decreases, and the chloride ion concentration increases. In addition, although the fluororesin solution of Comparative Example 2 has a low chloride ion concentration, it does not contain amine group-containing compounds, so the storage stability is poor (the fluororesin solution gels after heating, and the fluororesin solution cannot be measured. Mn). In addition, gelation occurred when the coating composition obtained using the solution of the fluorine-containing resin of Comparative Example 2 was produced, and the powder composition could not be produced, and the glossiness immediately after the film formation could not be evaluated. In addition, all the contents of the specification, the scope of the patent application, and the abstract of Japanese Patent Application No. 2016-005279 filed on January 14, 2016 are cited here, and incorporated as the disclosure of the specification of the present invention.

Claims (13)

A fluorine-containing resin solution containing: a fluorine resin containing a fluorine-containing polymer having chlorotrifluoroethylene-based units, an amine group-containing compound, and an organic solvent, and is determined by the following chloride ion concentration measurement method The chloride ion concentration is 50 mass ppm or less. The chloride ion concentration measurement method: prepare a sample solution by mixing the above-mentioned fluorine-containing resin solution with xylene. After mixing the obtained sample solution with water, the phase is separated into The xylene phase and the water phase, the water phase is recovered and the chloride ion concentration in the recovered water is measured by ion chromatography, and the content of the above-mentioned amine group-containing compound relative to 100 parts by mass of the above-mentioned fluororesin is 0.1~ 2.0 parts by mass. The fluorine-containing resin solution of claim 1, wherein the content of the above-mentioned chlorotrifluoroethylene-based units is 40-60 mol% relative to all the units of the above-mentioned fluoropolymer. The fluorine-containing resin solution of claim 1 or 2, wherein the chloride ion concentration is 3 mass ppm or more. A method for producing a fluorine-containing resin solution, which is characterized in that: in the presence of an amine group-containing compound and hydrotalcite, monomer components containing chlorotrifluoroethylene are polymerized in an organic solvent to obtain a fluorine-containing resin solution. The polymer mixture is followed by removing the insoluble components derived from the above hydrotalcite from the above mixture containing the fluoropolymer to produce a fluororesin solution, and At the time point when the monomer components start to polymerize, the ratio of the mass of the hydrotalcite to the mass of the amine-containing compound (mass of hydrotalcite/mass of the amine-containing compound) is set to 1 to 4, and The amount of the amine group-containing compound at the start of polymerization is 0.1 to 2.0 parts by mass relative to 100 parts by mass of the monomer component. The manufacturing method of claim 4, wherein the removal of the insoluble components derived from the hydrotalcite is performed by filtration, and after the polymerization and before the filtration, the hydrotalcite is added to the mixed liquid containing the fluoropolymer. Such as the manufacturing method of claim 4 or 5, wherein the amount of chlorotrifluoroethylene in the monomer component is 40-60 mol% relative to the total monomer component. The manufacturing method of claim 4 or 5, wherein the fluorine-containing resin solution is substantially free of hydrotalcite. Such as the manufacturing method of claim 4 or 5, wherein the chloride ion concentration in the solution of the fluorine-containing resin manufactured by the following chloride ion concentration measurement method is 50 mass ppm or less, the chloride ion concentration measurement method: The above-mentioned fluororesin solution and xylene are mixed to prepare a sample solution. After the obtained sample solution is mixed with water, the phase is separated into a xylene phase and an aqueous phase. The above-mentioned water is recovered and subjected to ion chromatography. Method to measure the chloride ion concentration in the water recovered above. The manufacturing method of claim 8, wherein the chloride ion concentration is 3 mass ppm or more. A coating composition containing the solution of the fluorine-containing resin according to any one of claims 1 to 3. A coating composition comprising a fluororesin composition obtained by removing an organic solvent from the fluororesin solution of any one of claims 1 to 3. The coating composition of claim 11, wherein the above-mentioned coating composition is a powdered coating composition. A coated article comprising a substrate and a coating film formed on the substrate by the coating composition according to any one of claims 10 to 12.