Resin composition and molded body

Abstract

[Problem] To provide: a resin composition containing a vinylidene fluoride polymer that has excellent transparency and is capable of suppressing yellowing; and a molded body. [Solution] A resin composition comprising a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant, wherein the antioxidant has a melting point of 130°C or lower and contains at least one selected from the group consisting of phenol-based compounds, phosphonic acid-based compounds, and phosphite-based compounds. This molded body contains the resin composition.

Description

Resin composition and molded article

[0001] The present invention relates to a resin composition and molded article containing a vinylidene fluoride polymer.

[0002] Vinylidene fluoride resins, including polyvinylidene fluoride polymers, are used in various fields due to their high strength, chemical resistance, heat resistance, and ferroelectric properties. Patent Document 1 discloses a polyvinylidene fluoride resin containing polyvinylidene fluoride polymer and alkyl quaternary ammonium bisulfate, which is one of the quaternary organic salts. Vinylidene fluoride resins containing alkyl quaternary ammonium bisulfate exhibit excellent transparency and are expected to be used in a wide range of fields, including applications in optical components.

[0003] Japanese Patent Application Publication No. 11-323052

[0004] However, resin compositions containing vinylidene fluoride polymer and quaternary organic salts have issues with thermal stability, and the resin composition may yellow due to heating during molding, etc.

[0005] Therefore, there is a need for resin compositions and molded articles containing a vinylidene fluoride polymer that has excellent transparency and can suppress yellowing.

[0006] The present disclosure provides: (1) A resin composition comprising a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant, wherein the antioxidant comprises at least one selected from the group consisting of phenolic compounds, phosphonic acid compounds, and phosphite compounds, and has a melting point of 130°C or less. (2) The resin composition according to (1), wherein the quaternary organic salt comprises a quaternary ammonium salt or a quaternary phosphonium salt. (3) The resin composition according to (1) or (2), wherein the quaternary organic salt comprises an alkyl quaternary ammonium sulfate. (4) The resin composition according to any one of (1) to (3), wherein the quaternary organic salt comprises one or more selected from the group consisting of tetraethylammonium bisulfate, tetrapropylammonium bisulfate, and tetrabutylammonium bisulfate. (5) The phosphite compound comprises the following formula (1) [In formula (1), R ａand R ｂThe resin composition according to any one of (1) to (4), wherein the phenolic compound comprises a hindered phenolic compound. (7) The phenolic compound comprises dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid)ethylenebis(oxyethylene), 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, A resin composition according to any one of (1) to (6), wherein the phosphonic acid compound comprises one or more selected from the group consisting of 1,6-hexanediolbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 4-[[4,6-bis(octylthio)-1,3,5-triazine-2-yl]amino]-2,6-di-tert-butylphenol. (8) A resin composition according to any one of (1) to (7), wherein the phosphonic acid compound comprises one or more selected from the group consisting of phosphonic acid, linear alkylphosphonic acid (having 1 to 18 carbon atoms), vinylphosphonic acid, allylphosphonic acid, (2-bromoethyl)phosphonic acid, and (2-chloroethyl)phosphonic acid. (9) A resin composition according to any one of (1) to (8), wherein the quaternary organic salt is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the vinylidene fluoride polymer, and the antioxidant is contained in an amount of 0.01 to 5 parts by mass per 100 parts by mass of the vinylidene fluoride polymer. (10) A resin composition according to any one of (1) to (9), wherein the heterogeneity of the vinylidene fluoride polymer is less than 4.0%. (11) A resin composition according to any one of (1) to (10), wherein the vinylidene fluoride polymer is contained in an amount of 95 parts by mass or more per 100 parts by mass of the resin composition. (12) A molded article containing the resin composition according to any one of (1) to (11).

[0007] According to this disclosure, it is possible to provide a resin composition and molded article containing a vinylidene fluoride polymer that has excellent transparency and can suppress yellowing.

[0008] The resin composition of this disclosure comprises a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant.

[0009] Herein, in this specification, "transparency" means that in a molded article with a thickness of 2 mm formed from a resin composition, the haze value is 40% or less. The haze value is more preferably 30% or less. The haze value (%) can be measured using a haze meter "NDH4000" (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136. "Suppression of yellowing" means that the YI value (Yellow Index) is 40 or less. The YI value is more preferably 30 or less. The YI value can be measured by reflection using a colorimeter "colormeter ZE6000" (manufactured by Nippon Denshoku Industries Co., Ltd.) with a white plate placed on the molded article, and calculated in accordance with ASTM E313. The YI value can be the average value of measurements taken at multiple locations (for example, four locations) on the molded article.

[0010] (Vinylidene Fluoride Polymer) A vinylidene fluoride polymer is a polymer whose main component is vinylidene fluoride. "Main component is vinylidene fluoride" means that polyvinylidene fluoride contains 50 mol% or more of constituent units derived from vinylidene fluoride. Polyvinylidene fluoride may be a homopolymer of vinylidene fluoride containing substantially 100 mol% of constituent units derived from vinylidene fluoride, or it may be a copolymer of vinylidene fluoride that further contains constituent units derived from other monomers.

[0011] Other monomers copolymerizable with vinylidene fluoride preferably include one or more selected from the group consisting of tetrafluoroethylene, trifluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, vinyl fluoride, 2,3,3,3-tetrafluoropropene, pentafluoropropene, perfluoromethyl vinyl ether, perfluoropropyl vinyl ether, and (meth)acrylic acid esters. Examples of (meth)acrylic acid esters include methyl (meth)acrylate or butyl (meth)acrylate. The content of constituent units derived from other monomers is preferably 10 mol% or less, more preferably 5 mol% or less, and even more preferably 2 mol% or less of the total of all constituent units.

[0012] The vinylidene fluoride polymer can be used alone or in combination of two or more types. For example, it can be a blend containing a vinylidene fluoride homopolymer and one or more vinylidene fluoride copolymers. From the viewpoint of stain resistance, ozone resistance, and solvent resistance, the vinylidene fluoride polymer is preferably a vinylidene fluoride homopolymer. On the other hand, from the viewpoint of flexibility and tear strength, it is preferable to use a vinylidene fluoride copolymer alone or a blend of a vinylidene fluoride copolymer and a vinylidene fluoride homopolymer. From the viewpoint of flexibility, the vinylidene fluoride copolymer is preferably a vinylidene fluoride-hexafluoropropylene copolymer.

[0013] The vinylidene fluoride polymer is preferably present in an amount of 95 parts by mass or more per 100 parts by mass of the resin composition.

[0014] (Heterogeneous bonding) In this embodiment, it is preferable that the proportion of heterogeneous bonding in the vinylidene fluoride polymer is less than 4.0%. Here, heterogeneous bonding refers to head-to-head bonding and tail-to-tail bonding in a polymer that is head-to-tail bonded. For example, in a vinylidene fluoride polymer, "CF ２ " and "CH ２ " and are joined together alternately, but within that, "CF ２ " and "CH ２there is a portion where "[CF ２ " groups or "[CH ２ " groups are bonded to each other, which is a heterogeneous bond.

[0015] The proportion of heterogeneous bonds in the vinylidene fluoride polymer is preferably less than 4.0% based on the total number of bonds. The proportion of heterogeneous bonds in the vinylidene fluoride polymer can be adjusted by the polymerization temperature in the production of the polymer. Alternatively, a commercially available polymer having a proportion of heterogeneous bonds within the above range may be used.

[0016] The proportion of heterogeneous bonds can be determined from １９ F-NMR measurement of the vinylidene fluoride polymer. More specifically, 40 mg of vinylidene fluoride polymer is dissolved in 0.8 ml of deuterated dimethylformamide (D7-DMF), and １９ F-NMR measurement is performed at room temperature. The obtained １９ F-NMR spectrum has five main peaks at positions of -91.6 ppm, -92.1 ppm, -94.7 ppm, -113.5 ppm, and -115.9 ppm. Among these peaks, the peaks at -113.5 ppm and -115.9 ppm are identified as peaks derived from heterogeneous bonds. Accordingly, where S0 is the sum of the areas of the five peaks, S1 is the area of the peak at -113.5 ppm, and S2 is the area of the peak at -115.9 ppm, the heterogeneous bond ratio is calculated by the following formula (F1):   Heterogeneous bond ratio (%) = [{(S1 + S2) / 2} / S0] × 100                  ···Formula (F1)

[0017] (Method for Producing Vinylidene Fluoride Polymer) Examples of the method for producing a vinylidene fluoride polymer include emulsion polymerization, soap-free emulsion polymerization, seed emulsion polymerization, suspension polymerization, miniemulsion polymerization, and solution polymerization. Among these, the vinylidene fluoride polymer is preferably produced by suspension polymerization.

[0018] (Quaternary organic salt) A quaternary organic salt contains a quaternary cation center that forms four covalent bonds. The quaternary cation center may be ammonium, phosphonium, or pyridinidinium. The quaternary cation center forms covalent bonds with alkyl groups or aryl groups. The quaternary organic salt preferably comprises a quaternary ammonium salt or a quaternary phosphonium salt, and more preferably comprises an alkyl or aryl quaternary ammonium salt, or an alkyl or aryl phosphonium salt. Examples of the salt include sulfate, halide, sulfonate, phosphonate, and phosphate. Among these, it is preferable to include an alkyl quaternary ammonium sulfate.

[0019] (Alkyl quaternary ammonium sulfate) The alkyl quaternary ammonium sulfate in the present embodiment is a compound represented by the following formula (2).

[0020] In formula (2), R １ to R ４ are alkyl groups having 1 to 10 carbon atoms that are the same or different from each other. Examples of the alkyl group include an ethyl group, a propyl group, an isopropyl group, a butyl group, a pentyl group, and a hexyl group. The total number of carbon atoms of the alkyl groups in R １ to R ４ is preferably 6 to 30, more preferably 6 to 24, and particularly preferably 8 to 20, from the viewpoint of ensuring sufficient transparency of the molded article.

[0021] In formula (1), R ５ is an alkyl group, a fluoroalkyl group, or a hydrogen atom. The alkyl group for R ５ is an alkyl group having 1 to 10 carbon atoms, such as a methyl group and an ethyl group. The fluoroalkyl group for R ５ is CF ３ , C ２ F ５ and other short-chain fluoroalkyl groups having 1 to 10 carbon atoms. R ５ is particularly preferably hydrogen.

[0022] Specific examples thereof include, for example, (C ２ H ５) ４ N ＋ , (C ３ H ７ ) ４ N ＋ , (C ４ H ９ ) ４ N ＋ , and (C ５ H １１ ) ４ N ＋ alkyl quaternary ammonium cations such as these, and CF ３ SO ４ － , CH ３ SO ４ － , HSO ４ － salts formed with anions such as these can be mentioned. These compounds may be used alone or in combination of two or more thereof.

[0023] In the present embodiment, the alkyl quaternary ammonium sulfate preferably includes alkyl quaternary ammonium hydrogen sulfate. It is preferable that at least one type of alkyl quaternary ammonium hydrogen sulfate is selected from the group consisting of tetraethylammonium hydrogen sulfate, tetrapropylammonium hydrogen sulfate, tetrabutylammonium hydrogen sulfate, tetrapentylammonium hydrogen sulfate, and tetrahexylammonium hydrogen sulfate. Among these, the alkyl quaternary ammonium hydrogen sulfate more preferably includes tetraethylammonium hydrogen sulfate, tetrapropylammonium hydrogen sulfate, or tetrabutylammonium hydrogen sulfate. The quaternary ammonium hydrogen sulfate preferably includes one or more selected from the group consisting of tetraethylammonium hydrogen sulfate, tetrapropylammonium hydrogen sulfate, and tetrabutylammonium hydrogen sulfate. The quaternary ammonium hydrogen sulfate further preferably includes tetrabutylammonium hydrogen sulfate. These compounds may be used alone or in combination of two or more thereof.

[0024] Other preferred alkyl quaternary ammonium salts besides the alkyl quaternary ammonium sulfates mentioned above include tetrabutylammonium fluoride, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, tetraethylammonium chloride, hexadecyltrimethylammonium chloride, diethyldioctadecylammonium bromide, tetrabutylammonium p-toluenesulfonate, tetrabutylammonium tetrafluoroborate, hexadecyltrimethylammonium hexafluorophosphate, tetrabutylammonium hexafluorophosphate, tetrabutylammonium hydroxide, tetrabutylammonium phosphate, di-TERT-butylammonium phosphate, tetrabutylammonium nitrate, tetrabutylammonium dichlorobromide, tetrabutylammonium thiocyanate, tetrabutylammonium salicylate, tetrabutylammonium acetate, or tetramethylammonium sulfate.

[0025] Preferred aryl quaternary ammonium salts include benzyltriethylammonium chloride or benzyltriethylammonium hydroxide.

[0026] Preferred alkyl quaternary phosphonium salts include tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tetrabutylphosphonium tetrafluoroborate, tetrabutylphosphonium hexafluorophosphate, tetrabutylphosphonium acetate, tetrabutylphosphonium tetraphenylborate, or tributyl(ethyl)phosphonium diethyl phosphate.

[0027] Preferred aryl quaternary phosphonium salts include tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, (2-carboxyethyl)triphenylphosphonium bromide, or benzyltriphenylphosphonium chloride.

[0028] To obtain sufficient transparency, the quaternary organic salt is preferably included in an amount of 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 0.8 parts by mass or more, and particularly preferably 1 part by mass or more, per 100 parts by mass of vinylidene fluoride polymer. To obtain sufficient transparency, the quaternary organic salt is preferably included in an amount of 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 6 parts by mass or less, and particularly preferably 5 parts by mass or less, per 100 parts by mass of vinylidene fluoride polymer. To obtain sufficient transparency, the quaternary organic salt is preferably included in an amount of 0.1 to 10 parts by mass, 0.5 to 8 parts by mass, 0.8 to 6 parts by mass, or 1 to 5 parts by mass, per 100 parts by mass of vinylidene fluoride polymer.

[0029] (Antioxidant) The antioxidant comprises at least one selected from the group consisting of phenolic compounds, phosphonic acid compounds, and phosphite compounds, and the melting point of the antioxidant is 130°C or lower. Herein, in this specification, the melting point of the antioxidant means the melting point disclosed in the Safety Data Sheet (SDS).

[0030] The phenolic compounds preferably include hindered phenolic compounds. Here, "hindered" means sterically hindered, and "hindered phenol" means a phenol in which both ortho positions are substituted with bulky functional groups.

[0031] Hindered phenol compounds include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid)ethylenebis(oxyethylene), 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, Preferably, it contains one or more selected from the group consisting of 1,6-hexanediolbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 4-[[4,6-bis(octylthio)-1,3,5-triazine-2-yl]amino]-2,6-di-tert-butylphenol.

[0032] The phenolic compound preferably has a 3,5-t-butyl-4-hydroxyphenyl group and preferably contains dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], or octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. More preferably, the phenolic compound contains one or more selected from the group consisting of dibutylhydroxytoluene, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, and 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0033] Phosphate antioxidants are defined by the following formula (1) [In formula (1), R ａ and R ｂIt is preferable that the compound contains compounds represented by [where is a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, which may be the same or different from each other]. The alkyl group is preferably a linear or branched alkyl group having 1 to 30 carbon atoms. The alkyl group is preferably having 6 to 24 carbon atoms, and more preferably 8 to 18 carbon atoms. Examples of such alkyl groups include 2-ethylhexyl group, nonyl group, decyl group, isodecyl group, octadecyl group, etc., with isodecyl group or octadecyl group being particularly preferred. Examples of substituents include phenyl group, phenol group, tert-butylphenol group, di-tert-butylphenol group, 3,5-t-butyl-4-hydroxyphenyl group, etc., preferably R ａ and R ｂ It is an unsubstituted alkyl group.

[0034] The phosphite antioxidant more preferably contains O,O'-dialkyl(C8-C18)pentaerythritol diphosphite, and even more preferably contains 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane, or bis(isodecyl)pentaerythritol diphosphite. Commercial phosphite antioxidants can be used. Examples of commercially available 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane include Adeka Stab PEP-8 (Adeka Corporation), and an example of a commercially available bis(isodecyl)pentaerythritol diphosphite is JPE-10 (Johoku Chemical Co., Ltd.).

[0035] The phosphonic acid compound preferably contains one or more selected from the group consisting of phosphonic acid, linear alkylphosphonic acid (1 to 18 carbon atoms), vinylphosphonic acid, allylphosphonic acid, (2-bromoethyl)phosphonic acid, and (2-chloroethyl)phosphonic acid. Of these, the phosphonic acid compound is particularly preferably phosphonic acid or n-octylphosphonic acid.

[0036] The antioxidants mentioned above can be used individually or in combination of two or more.

[0037] The antioxidant is preferably included in an amount of 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.008 parts by mass or more, and particularly preferably 0.01 parts by mass or more, per 100 parts by mass of vinylidene fluoride polymer, in order to effectively reduce the haze value and YI value. The antioxidant is preferably included in an amount of 5 parts by mass or less, 3 parts by mass or less, more preferably 2 parts by mass or less, even more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and particularly preferably 0.5 parts by mass or less, per 100 parts by mass of vinylidene fluoride polymer, in order to effectively reduce the haze value and YI value. In order to effectively reduce the haze value and YI value, the antioxidant is preferably included in an amount of 0.001 to 5 parts by mass, 0.005 to 3 parts by mass, 0.005 to 2 parts by mass, 0.005 to 1 part by mass, 0.008 to 0.8 parts by mass, or 0.01 to 0.5 parts by mass per 100 parts by mass of vinylidene fluoride polymer.

[0038] (Optional Components) The resin composition according to this embodiment may further contain optional components. Other components include additives and polymers other than those described above. Examples of additives include heat stabilizers, ultraviolet absorbers, light stabilizers, lubricants, plasticizers, bluing agents, or color inhibitors. The resin composition may contain one or more optional components.

[0039] (Method for producing the resin composition) As a method for producing the resin composition according to this embodiment, for example, the resin composition can be obtained by mixing a powder or pellet of vinylidene fluoride polymer with a quaternary organic salt.

[0040] Examples of equipment for mixing materials for resin compositions include Henschel blenders, cylindrical mixers, screw mixers, screw extruders, turbulators, Nauter mixers, V-type mixers, ribbon mixers, dual-arm kneaders, fluidized bed mixers, airflow mixers, rotary disc mixers, roll mixers, rolling mixers, and Reidige mixers.

[0041] A pelletized resin composition can be obtained by drying a mixture of polyvinylidene fluoride and a quaternary organic salt, and then melt-extruding the resulting dried material. Examples of extruders include single-screw extruders, co-direction twin-screw extruders, and anomalous-direction twin-screw extruders.

[0042] The resin composition of this disclosure, by including a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant, can suppress yellowing while maintaining excellent transparency in molded articles formed from the resin composition. Surprisingly, by including a specific antioxidant with a melting point of 130°C or lower, it is possible to not only lower the YI value but also further lower the haze value compared to the case where only vinylidene fluoride polymer and a quaternary organic salt are included. Although not bound by theory, it is presumed that the 130°C melting point of the antioxidant allows for good dispersion of the antioxidant in the resin composition, contributing to the reduction in both the YI value and the haze value.

[0043] (Molded Article) The molded article of this disclosure comprises the resin composition described above. The molded article can be any shape as long as it is formed from the resin composition described above. For example, the molded article can be an injection-molded article, a pipe, a round bar, a square bar, a sheet, a film, or a fiber. The molded article can be manufactured by any manufacturing method, for example, by injection molding or press molding, calendering, extrusion molding, melt spinning, etc.

[0044] Injection molding is a method of obtaining a molded product by, for example, supplying a resin composition to an injection molding machine, melting it by heating, pouring it into a mold, injecting it, and slowly cooling it.

[0045] Press molding is a method of obtaining a molded product by placing a resin composition in a mold, applying high-temperature press (for example, 230°C for 3 minutes at a pressure of 5 MPa) using a compression molding machine, and then applying cold press (for example, 30°C for 3 minutes). The mold used in press molding can be any material that can be used for heating and pressurizing and that can hold the molten resin composition in the shape to be molded. Examples of such molds include metal molds and metal sheets such as aluminum foil.

[0046] The form of the resin composition is arbitrary as long as it is applicable to the molding method. The resin composition can be, for example, a powder, pellets, flakes, a compressed powder product, or a molded product contained in a mold. In the manufacture of the molded product, the resin composition is heated to a temperature at which it is fully melted and then molded.

[0047] In this embodiment, when the molded body is in the shape of a sheet, it is preferable to pressurize the molten resin composition from the viewpoint of achieving a uniform thickness and a smooth surface of the molded body. That is, in press molding, it is preferable to melt the resin composition by heating the press member and then press it with the press member to form it into a sheet shape. The press member can be any known member capable of achieving the aforementioned heating and pressurizing. The pressure for cold pressing may be the same as or different from that used in high-temperature pressing. The temperature and time for cold pressing can be determined as appropriate. For example, the temperature may be 5°C or higher and 40°C or lower, and the time may be 2 minutes or higher and 10 minutes or lower.

[0048] The method for manufacturing the molded article may further include other steps, to the extent that the effects of this embodiment can be obtained. Examples of such other steps include a preheating step of preheating the mold prior to molding, a molded article manufacturing step of producing a molded article of the resin composition in the mold, a slow cooling step of slowly cooling the molded article after heat and pressure molding, and an annealing step of annealing the obtained molded article.

[0049] In the molded article of this disclosure, the resin composition contains a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant, thereby achieving excellent transparency while suppressing yellowing. The molded article of this disclosure can have a YI value of 40 or less, more preferably 30 or less, and a haze value of 40% or less, more preferably 30% or less, at a thickness of 2 mm.

[0050] The present invention will be specifically described based on the following examples, but the present invention is not limited to these examples.

[0051] The following materials were used in the examples and comparative examples: TBAHS: Tetrabutylammonium bisulfate TEAHS: Tetraethylammonium bisulfate TPAHS: Tetrapropylammonium bisulfate PEP-8: 3,9-bis(octadecyloxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane (Adeka Stab PEP-8, Adeka Corporation) Melting point 44-47°C JPE-10: Bis(isodecyl)pentaerythritol diphosphite Melting point below 25°C BHT: Dibutylhydroxytoluene Melting point 70°C Antioxidant 1076: Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate Melting point 50-55°C Antioxidant 1035: 2,2'-Thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] Melting point 78°C Phosphonic acid: Cas No. 13598-36-2 Melting point 73°C OPA: n-octylphosphonic acid melting point 101°C PEP-36: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane (Adeka Stab PEP-36, Adeka Corporation) Melting point 234-240°C HP-10: 2,2'-methylenebis(4,6-di-tert-butylphenyl)2-ethylhexyl phosphite (Adeka Stab HP-10, Adeka Corporation) Melting point 146-152°C

[0052] (Example 1) In a 2-liter autoclave, 1100 g of deionized water was added as a dispersion medium, 0.13 g of Metrose SM-100 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a cellulose-based suspension agent, 3.4 g of 50 wt% diisopropyl peroxydicarbonate-HFE-347pc-f solution as a polymerization initiator, 17.4 g of ethyl acetate as a chain transfer agent, and 430 g of vinylidene fluoride (VDF) were charged. The temperature was raised to 26°C over 40 minutes. Then, while maintaining the temperature at 25°C, the temperature was raised to 40°C over 2 hours when the pressure in the system decreased to 3.5 MPa. The reaction was then continued while maintaining the temperature at 40°C until the pressure in the system decreased to 1.4 MPa. After polymerization was complete, the polymer slurry was heat-treated at 95°C for 60 minutes, then dehydrated, washed with water, and further dried at 80°C for 20 hours to obtain a powder of vinylidene fluoride polymer (PVDF). The physical properties of the obtained vinylidene fluoride polymer were an inherent viscosity of 1.0 dL / g, a melting point of 173°C, and heterogeneity of 3.8%.

[0053] To 100 parts by mass of the vinylidene fluoride polymer obtained by the above procedure, 2.0 parts by mass of tetrabutylammonium bisulfate (TBAHS) as a quaternary organic salt and 0.05 parts by mass of Adekastab PEP-8 as an antioxidant were added. The vinylidene fluoride polymer used was the one obtained in Example 1. Next, the mixture was extruded using a co-screw extruder (TEM-26, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 190°C to obtain a pelletized resin composition.

[0054] The obtained pelletized resin composition was sandwiched between aluminum foil and then between stainless steel (SUS) plates, and pressed at 220°C for 5 minutes at a pressure of 10 MPa using a compression molding machine (manufactured by Shinto Metal Industries Co., Ltd., model AYSR-5). Next, the pressed product was immediately cooled (rapidly cooled) by holding it in a cold press at 30°C for 3 minutes while still sandwiched between the SUS plates. This produced a sheet-like molded body. The thickness of the molded body was measured five times per sample using a thickness gauge "DG-925" (manufactured by Ono Sokki Co., Ltd.), and the average value was calculated. This average value was taken as the thickness of the molded body. In Example 1, the thickness of the molded body was 2 mm.

[0055] In Examples 2 to 19 and Comparative Examples 1 to 10, molded bodies were obtained using the same procedure as in Example 1, except that the type of quaternary organic salt, the amount of quaternary organic salt added, the type of antioxidant, or the amount of antioxidant added were changed, as shown in Table 1. The thickness of the molded bodies was 2 mm in all cases.

[0056] The haze and YI values ​​of the molded body were measured using the following method.

[0057] [Haze Value] The haze value of the molded product was measured using a haze meter "NDH4000" (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS K7136.

[0058] [YI Value] The YI value of the molded body was measured using the colormeter ZE6000 (manufactured by Nippon Denshoku Industries Co., Ltd.) with a white plate placed on the molded body and measured by the reflection method, and calculated according to ASTM E313. In addition, four arbitrary points on the molded body were measured, and the average value was taken as the YI value of the molded body.

[0059]

[0060] Comparing Comparative Example 1 with Comparative Example 5, it was found that although the haze value improved with the quaternary organic salt, the YI value increased significantly, indicating strong yellowing. On the other hand, comparing Comparative Example 5 with Comparative Examples 6-10, it was found that the haze value did not improve with the antioxidant, and yellowing was even more severe. Comparative Examples 2-4 contained antioxidants with melting points exceeding 140°C, but when such antioxidants were included, the YI value exceeded 40, and yellowing of the molded article could not be suppressed.

[0061] In contrast, Examples 1 to 19 showed that by including a quaternary organic salt and an antioxidant with a melting point of 130°C or lower, the YI value could be reduced to 40 or lower, suppressing yellowing, and the haze value could also be reduced compared to Comparative Example 1, which did not contain an oxidizing agent.

Claims

1. A resin composition comprising a vinylidene fluoride polymer, a quaternary organic salt, and an antioxidant, wherein the antioxidant comprises at least one selected from the group consisting of phenolic compounds, phosphonic acid compounds, and phosphite compounds, and has a melting point of 130°C or lower.

2. The resin composition according to claim 1, wherein the quaternary organic salt comprises a quaternary ammonium salt or a quaternary phosphonium salt.

3. The resin composition according to claim 1, wherein the quaternary organic salt comprises an alkylquaternary ammonium sulfate.

4. The resin composition according to claim 1, wherein the quaternary organic salt comprises one or more selected from the group consisting of tetraethylammonium bisulfate, tetrapropylammonium bisulfate, and tetrabutylammonium bisulfate.

5. The phosphite compound is of the following formula (1) [In formula (1), R ａ and R ｂ The resin composition according to claim 1, wherein [represented by substituted or unsubstituted alkyl groups having 1 to 30 carbon atoms, which may be the same or different from each other].

6. The resin composition according to claim 1, wherein the phenolic compound comprises a hindered phenolic compound.

7. The phenolic compounds include dibutylhydroxytoluene, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, bis(3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid)ethylenebis(oxyethylene), 2,2'-thiodiethylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octyl 3-(4-hydroxy-3,5-diisopropylphenyl)propionate, The resin composition according to claim 1, comprising one or more selected from the group consisting of 1,6-hexanediolbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and 4-[[4,6-bis(octylthio)-1,3,5-triazine-2-yl]amino]-2,6-di-tert-butylphenol.

8. The resin composition according to claim 1, wherein the phosphonic acid compound comprises one or more selected from the group consisting of phosphonic acid, linear alkylphosphonic acid (having 1 to 18 carbon atoms), vinylphosphonic acid, allylphosphonic acid, (2-bromoethyl)phosphonic acid, and (2-chloroethyl)phosphonic acid.

9. The resin composition according to claim 1, wherein the quaternary organic salt is contained in an amount of 0.1 to 5 parts by mass per 100 parts by mass of the vinylidene fluoride polymer, and the antioxidant is contained in an amount of 0.01 to 5 parts by mass per 100 parts by mass of the vinylidene fluoride polymer.

10. The resin composition according to claim 1, wherein the heterogeneity of the vinylidene fluoride polymer is less than 4.0%.

11. The resin composition according to claim 1, wherein the resin composition contains 95 parts by mass or more of the vinylidene fluoride polymer per 100 parts by mass of the resin composition.

12. A molded article comprising the resin composition according to any one of claims 1 to 11.

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