JP2009029851A - Sulfonyl compound and method for producing sulfonyl compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surfactant comprising a sulfonyl compound, which can be suitably used as an emulsifier in emulsion polymerization of a fluorine-containing polymer, an aqueous dispersion, and a method for producing a fluorine-containing polymer. <P>SOLUTION: The surfactant comprises a sulfonyl compound represented by general formula (I), wherein Rf denotes H or a 3-6C fluoroalkyl group; m denotes 0 or 1; and Y denotes a carboxyl group or a sulfonic acid group, and a salt thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a sulfonyl compound, a method for producing a sulfonyl compound, a surfactant, an aqueous dispersion, and a method for producing a fluoropolymer.

As a method for producing a fluorine-containing polymer, a method of polymerizing tetrafluoroethylene [TFE] by using a fluorine-substituted carboxylic acid having a linear or partially branched chain as a surfactant in an aqueous medium is known. (See Patent Document 1, Patent Document 2 and Patent Document 3).

In recent years, a method of using a carboxylic acid having a fluorinated polyoxyalkylene group as a surfactant has also been disclosed as a method for producing a fluoropolymer (see Patent Document 4).

However, these surfactants are very stable thermally and chemically and are useful in that they can suppress side reactions such as chain transfer during polymerization, but they are removed from the resin obtained by polymerization. In order to do so, there has been a problem that conditions such as cleaning and heating are limited.

In view of the above problems, Patent Document 5 discloses that in an aqueous medium using a surfactant that has a small residual amount in a fluoropolymer particle after processing such as aggregation without impairing stability during polymerization. Method for producing a fluoropolymer, and fluoropolymer using a surfactant that is excellent in dispersion stability of the fluoropolymer and has a small residual amount in the fluoropolymer particles after processing such as agglomeration Aqueous dispersions are being considered.

However, 2-acyloxycarboxylic acid described in Patent Document 5 has a complicated synthesis route and a low yield. Moreover, when the half ester compound described in Patent Document 5 is used as an emulsifier for emulsion polymerization of a fluorine-based monomer, hydrogen atoms present in the molecule cause a chain transfer reaction, the polymerization rate decreases, and the high molecular weight There was also a problem that the polymer was not obtained.

JP 61-207413 A JP 61-228008 A Japanese Patent Laid-Open No. 10-212261 US Pat. No. 6,429,258 JP 2005-48178 A

In view of the above situation, the present invention provides a surfactant comprising a sulfonyl compound, an aqueous dispersion, and a method for producing a fluorine-containing polymer that can be suitably used as an emulsifier in emulsion polymerization of a fluorine-containing polymer.

（式中Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。）で表されるスルホニル化合物からなることを特徴とする界面活性剤である。 The present invention relates to the following general formula (I)

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). A surfactant comprising a sulfonyl compound.

（式中Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。）で表されるスルホニル化合物を含む水性媒体中で、含フッ素モノマーの重合を行う工程を含むことを特徴とする含フッ素ポリマーの製造方法でもある。
本発明はまた、上記スルホニル化合物の含有量が、水性媒体１００質量％に対して０．０００１〜２質量％である上記の含フッ素ポリマーの製造方法でもある。 The present invention also provides the following general formula (I):

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). It is also a method for producing a fluorine-containing polymer, comprising a step of polymerizing a fluorine-containing monomer in an aqueous medium containing a sulfonyl compound.
The present invention is also a method for producing the above-mentioned fluoropolymer, wherein the content of the sulfonyl compound is 0.0001 to 2% by mass with respect to 100% by mass of the aqueous medium.

（式中Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。）で表されるスルホニル化合物、及び、含フッ素ポリマーを含有する水性分散体であって、含フッ素ポリマーの平均粒子径は、５０〜５００ｎｍであることを特徴とする水性分散体でもある。 The present invention also provides the following general formula (I):

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). An aqueous dispersion containing a sulfonyl compound and a fluorinated polymer, wherein the fluorinated polymer has an average particle size of 50 to 500 nm.

The present invention also provides the step (I) of bringing the aqueous dispersion into contact with an anion exchange resin in the presence of a nonionic surfactant, and the aqueous dispersion obtained in the step (I) in the aqueous dispersion. It is also a manufacturing method of the refinement | purification aqueous dispersion characterized by including the process (II) concentrated so that solid content concentration may be 30-70 mass% with respect to 100 mass% of aqueous dispersion.
The present invention is also a fine powder produced by coagulating the aqueous dispersion.

（式中Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。）で表されるスルホニル化合物を回収し、精製する工程を含むことを特徴とする再生スルホニル化合物の製造方法でもある。
以下、本発明を詳細に説明する。 The present invention also includes at least one component selected from the wastewater generated by the coagulation, the wastewater generated by washing, and the off-gas generated in the drying step, from the following general formula (I):

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). It is also a method for producing a regenerated sulfonyl compound, comprising a step of recovering and purifying the sulfonyl compound.
Hereinafter, the present invention will be described in detail.

The sulfonyl compound of the present invention exhibits excellent performance as a surfactant. In particular, when used for the polymerization of a fluoropolymer, a high molecular weight fluoropolymer can be obtained. In addition, since the sulfonyl group present in the molecule exhibits a strong electron withdrawing property, the terminal sulfonic acid group or carboxyl group exhibits a strong hydrophilic property, and has an excellent performance as a surfactant even if the carbon chain of Rf is long. Can be shown.

で表されるものである。上記一般式（Ｉ）において、Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。上記Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基であることが好ましい。また、上記Ｒｆは、Ｃ、Ｆ、Ｏからなることが好ましい。また、ｍ＝１である場合のベンゼン環上の置換は、メタ位又はパラ位であることが好ましい。 The sulfonyl compound is represented by the following general formula (I)

It is represented by In the general formula (I), Rf represents H and a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof. Rf is preferably H and a fluoroalkyl group having 3 to 6 carbon atoms. The Rf is preferably composed of C, F, and O. The substitution on the benzene ring when m = 1 is preferably at the meta or para position.

As a method for producing the sulfonyl compound, a known method can be used, for example, a method disclosed in a pamphlet of WO2004 / 072021.

The sulfonyl compound can be suitably used as a surfactant. The surfactant comprising the sulfonyl compound is one aspect of the present invention. The surfactant of the present invention can be used as a surfactant as long as it contains at least one sulfonyl compound represented by the above general formula (I), but contains two or more sulfonyl compounds. It may be.

Since the surfactant of the present invention is composed of the sulfonyl compound, it can exhibit an appropriate surface activity in various applications. The surfactant of the present invention can be used for applications such as production of fluorine-containing polymers.

The present invention is also a method for producing a fluorine-containing polymer, comprising a step of polymerizing a fluorine-containing monomer in an aqueous medium containing the sulfonyl compound described above.

In the method for producing a fluorine-containing polymer of the present invention, if at least one of the sulfonyl compounds is used as a surfactant, the fluorine-containing polymer can be produced efficiently. Further, in the method for producing a fluoropolymer of the present invention, two or more of the sulfonyl compounds may be used simultaneously as a surfactant, or remain in a molded body made of a volatile polymer or a fluoropolymer. If it is good, other compounds having surface activity than the sulfonyl compound may be used at the same time. As the other compounds having surface activity, those described above can be used.
Moreover, in the manufacturing method of the fluorine-containing polymer of this invention, in addition to the said sulfonyl compound and the compound which has other surface active ability used as needed, an additive can be used in order to stabilize each compound. What was mentioned above can be used as said additive.

In the method for producing a fluorine-containing polymer of the present invention, the polymerization is carried out by charging the polymerization reactor with an aqueous medium, the sulfonyl compound, a monomer and other additives as required, stirring the contents of the reactor, and reacting. The vessel is maintained at a predetermined polymerization temperature, and then a predetermined amount of a polymerization initiator is added to start the polymerization reaction. After the polymerization reaction is started, a monomer, a polymerization initiator, a chain transfer agent, the sulfonyl compound, and the like may be additionally added depending on the purpose.
In the above polymerization, the polymerization temperature is usually 5 to 120 ° C., and the polymerization pressure is 0.05 to 10 MPaG. The polymerization temperature and polymerization pressure are appropriately determined depending on the type of monomer used, the molecular weight of the target fluoropolymer, and the reaction rate.

The sulfonyl compound is preferably added in a total amount of 0.0001 to 2% by mass with respect to 100% by mass of the aqueous medium. A more preferable lower limit is 0.001% by mass, and a more preferable upper limit is 1% by mass. If the amount is less than 0.0001% by mass, the dispersion force may be insufficient. If the amount exceeds 2% by mass, an effect commensurate with the amount added cannot be obtained, and on the contrary, the polymerization rate may decrease or the reaction may stop. There is. The amount of the compound added is appropriately determined depending on the type of monomer used, the molecular weight of the target fluoropolymer, and the like.

The polymerization initiator is not particularly limited as long as it can generate radicals in the polymerization temperature range, and known oil-soluble and / or water-soluble polymerization initiators can be used. Furthermore, the polymerization can be started as a redox in combination with a reducing agent or the like. The concentration of the polymerization initiator is appropriately determined depending on the type of monomer, the molecular weight of the target fluoropolymer, and the reaction rate.

The aqueous medium is a reaction medium for performing polymerization and means a liquid containing water. The aqueous medium is not particularly limited as long as it contains water, and water and, for example, a fluorine-free organic solvent such as alcohol, ether, and ketone, and / or a fluorine-containing organic solvent having a boiling point of 40 ° C. or lower. May be included. For example, when carrying out suspension polymerization, a fluorine-containing organic solvent such as C318 can be used.
In the above polymerization, a known chain transfer agent and radical scavenger may be further added depending on the purpose to adjust the polymerization rate and molecular weight.

The fluorine-containing polymer is obtained by polymerizing a fluorine-containing monomer, and may be obtained by copolymerizing a fluorine-free monomer depending on the purpose.

The fluorine-containing monomer may be a fluoroolefin, preferably a fluoroolefin having 2 to 10 carbon atoms; a cyclic fluorinated monomer; a formula CY ² ₂ = CY ² OR or CY ² ₂ = CY ² OR. ² OR ³ (Y ² is H or F, R and R ³ are alkyl groups having 1 to 8 carbon atoms in which some or all of the hydrogen atoms are substituted with fluorine atoms, and R ² is hydrogen And a fluorinated alkyl vinyl ether represented by a C1-C8 alkylene group in which some or all of the atoms are substituted with fluorine atoms.

The fluoroolefin preferably has 2 to 6 carbon atoms. Examples of the fluoroolefin having 2 to 6 carbon atoms include tetrafluoroethylene [TFE], hexafluoropropylene [HFP], chlorotrifluoroethylene [CTFE], vinyl fluoride, vinylidene fluoride [VDF], Fluoroethylene, hexafluoroisobutylene, perfluorobutylethylene and the like can be mentioned. The cyclic fluorinated monomer is preferably perfluoro-2,2-dimethyl-1,3-dioxole [PDD], perfluoro-2-methylene-4-methyl-1,3-dioxolane [ PMD] and the like.
In the fluorinated alkyl vinyl ether, R and R ³ are preferably those having 1 to 4 carbon atoms, more preferably all hydrogen atoms are substituted with fluorine, and R ² Preferably has 2 to 4 carbon atoms, more preferably all of the hydrogen atoms are replaced by fluorine atoms.

Examples of the fluorine-free monomer include hydrocarbon monomers having reactivity with the fluorine-containing monomer. Examples of the hydrocarbon monomer include alkenes such as ethylene, propylene, butylene, and isobutylene; alkyl vinyl ethers such as ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, isobutyl vinyl ether, and cyclohexyl vinyl ether; vinyl acetate, vinyl propionate, n -Vinyl butyrate, vinyl isobutyrate, vinyl valerate, vinyl pivalate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl versatate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, benzoic acid Vinyl, vinyl para-t-butylbenzoate, vinyl cyclohexanecarboxylate, vinyl monochloroacetate, vinyl adipate, vinyl acrylate, vinyl methacrylate, croto Vinyl esters such as vinyl acid vinyl, vinyl sorbate, vinyl cinnamate, vinyl undecylenate, vinyl hydroxyacetate, vinyl hydroxypropioate, vinyl hydroxybutyrate, vinyl hydroxyvalerate, vinyl hydroxyisobutyrate and vinyl hydroxycyclohexanecarboxylate Alkyl allyl ethers such as ethyl allyl ether, propyl allyl ether, butyl allyl ether, isobutyl allyl ether, and cyclohexyl allyl ether; alkyl allyl ethers such as ethyl allyl ester, propyl allyl ester, butyl allyl ester, isobutyl allyl ester, and cyclohexyl allyl ester Examples include esters.

The fluorine-free monomer may also be a functional group-containing hydrocarbon monomer. Examples of the functional group-containing hydrocarbon monomers include hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, hydroxyisobutyl vinyl ether, hydroxycyclohexyl vinyl ether; itaconic acid, succinic acid, succinic anhydride, fumaric acid Non-fluorine-containing monomers having a carboxyl group such as acid, fumaric anhydride, crotonic acid, maleic acid, maleic anhydride, perfluorobutenoic acid; non-fluorine-containing monomers having a glycidyl group such as glycidyl vinyl ether and glycidyl allyl ether; aminoalkyl Non-fluorine-containing monomers having amino groups such as vinyl ether and aminoalkyl allyl ether; (meth) acrylamide, methylol acrylic Fluorine-containing monomers having an amide group of the amide.

As the fluorine-containing polymer suitably produced by the method for producing a fluorine-containing polymer of the present invention, a TFE polymer in which the monomer having the highest molar fraction of the monomer in the polymer (hereinafter, “most monomer”) is TFE, the most Examples thereof include a VDF polymer in which the monomer is VDF, a CTFE polymer in which the most monomer is CTFE, and the like.

The TFE polymer may preferably be a TFE homopolymer, or (1) TFE, (2) one or two or more fluorine-containing monomers other than TFE having 2 to 8 carbon atoms. In particular, it may be a copolymer comprising HFP or CTFE and (3) other monomers. (3) Other monomers include, for example, fluoro (alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms; fluorodioxole; perfluoroalkylethylene; And hydroperfluoroolefin.
The TFE polymer may also be a copolymer of TFE and one or more fluorine-free monomers. Examples of the fluorine-free monomer include alkenes such as ethylene and propylene; vinyl esters; vinyl ethers. The TFE polymer is also a copolymer of TFE, one or more fluorine-containing monomers having 2 to 8 carbon atoms, and one or more fluorine-free monomers. Also good.

The VDF polymer may preferably be a VDF homopolymer [PVDF], or (1) VDF, (2) other than one or two or more VDFs having 2 to 8 carbon atoms. A copolymer comprising fluoroolefin, particularly TFE, HFP or CTFE, and (3) perfluoro (alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms, etc. Also good.

The CTFE polymer may suitably be a CTFE homopolymer, (1) CTFE, (2) one or more fluoroolefins other than CTFE having 2 to 8 carbon atoms, In particular, it may be a copolymer comprising TFE or HFP and (3) perfluoro (alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms.
The CTFE polymer may also be a copolymer of CTFE and one or more fluorine-free monomers. Examples of the fluorine-free monomers include alkenes such as ethylene and propylene; vinyl Esters; vinyl ethers and the like.

The fluoropolymer produced by the method for producing a fluoropolymer of the present invention can be glassy, plastic or elastomeric. These are amorphous or partially crystalline and can be subjected to compression firing, melt processing or non-melt processing.
In the method for producing a fluoropolymer of the present invention, for example, (I) a polytetrafluoroethylene polymer [PTFE polymer] is used as a non-melt processable resin, and (II) an ethylene / TFE copolymer is used as a melt processable resin. Copolymer [ETFE], TFE / HFP copolymer [FEP] and TFE / perfluoro (alkyl vinyl ether) copolymer [PFA, MFA, etc.] are (III) TFE / propylene copolymer as an elastomeric copolymer. , TFE / propylene copolymer / third monomer copolymer (the third monomer is VDF, HFP, CTFE, perfluoro (alkyl vinyl ether), etc.), a copolymer comprising TFE and perfluoro (alkyl vinyl ether). Polymer; HFP / ethylene copolymer, HFP / ethylene / TFE copolymer; PVDF; VD / HFP copolymers, HFP / ethylene copolymers, thermoplastic elastomers such as VDF / TFE / HFP copolymers; and fluorine-containing segmented polymers described in JP-B-61-49327 are suitably produced. sell.
The perfluoro (alkyl vinyl ether) has the formula:
Rf ² (OCFQCF ₂ ) _k1 (OCR ⁴ Q ² CF ₂ CF ₂ ) _{k 2} (OCF ₂ ) _{k 3} OCF = CF ₂
(Wherein, Rf ² is .k1 represents a perfluoroalkyl group having 1 to 6 carbon atoms, k2 and k3, are integers of the same or different may be 0 to 5 .Q, ^{Q 2} and ^{R 4} are Are the same or different and are F or CF _3. )

The above-mentioned (I) non-melt processable resin, (II) melt-processable resin and (III) elastomeric polymer which are preferably produced by the method for producing a fluoropolymer of the present invention are produced in the following manner. Is preferred.

(I) Non-melt processable resin In the method for producing a fluoropolymer of the present invention, the PTFE polymer is usually polymerized at a polymerization temperature of 10 to 100C and a polymerization pressure of 0.05 to 5 MPaG. .
In the polymerization, pure water and the sulfonyl compound are charged into a pressure-resistant reaction vessel equipped with a stirrer, and after deoxygenation, TFE is charged to a predetermined temperature, and a polymerization initiator is added to start the reaction. Since the pressure decreases as the reaction proceeds, additional TFE is added continuously or intermittently so as to maintain the initial pressure. When a predetermined amount of TFE is supplied, the supply is stopped, the TFE in the reaction vessel is purged, the temperature is returned to room temperature, and the reaction is terminated.

In the production of the PTFE polymer, various known modifying monomers can be used in combination. In the present specification, the polytetrafluoroethylene polymer [PTFE polymer] is not only a TFE homopolymer but also a copolymer of TFE and a modified monomer, which is non-melt processable (hereinafter referred to as “ This is a concept including “modified PTFE”.
Examples of the modifying monomer include perhaloolefins such as HFP and CTFE; fluoro (alkyl vinyl ether) having an alkyl group having 1 to 5 carbon atoms, particularly 1 to 3 carbon atoms; and a ring such as fluorodioxole. Fluorinated monomers of the formula; perhaloalkylethylenes; ω-hydroperhaloolefins and the like. Depending on the purpose and the supply of TFE, the supply of the modified monomer can be performed by initial batch addition or by continuous or intermittent addition.
The modified monomer content in the modified PTFE is usually in the range of 0.001 to 2 mol%.

In the production of the PTFE polymer, the sulfonyl compound can be used in the range of use in the production method of the fluorine-containing polymer of the present invention described above. Usually, the amount of the aqueous medium is 0.0001 to 2% by mass. Added. The concentration of the sulfonyl compound is not particularly limited as long as it is in the above range, but it is usually added at a critical micelle concentration (CMC) or less at the start of polymerization. When the addition amount is large, acicular particles having a large aspect ratio are formed, and the aqueous dispersion becomes a gel and the stability is impaired.

In the production of the PTFE polymer, as a polymerization initiator, a persulfate (for example, ammonium persulfate) or an organic peroxide such as disuccinic acid peroxide or diglutaric acid peroxide is used alone or in the form of a mixture thereof. can do. Further, it may be used in combination with a reducing agent such as sodium sulfite to make a redox system. Furthermore, a radical scavenger such as hydroquinone or catechol can be added during polymerization, or a peroxide decomposing agent such as ammonium sulfite can be added to adjust the radical concentration in the system.

In the production of the PTFE polymer, known chain transfer agents can be used, for example, saturated hydrocarbons such as methane, ethane, propane and butane, and halogenated hydrocarbons such as chloromethane, dichloromethane and difluoroethane. In addition, alcohols such as methanol and ethanol, hydrogen and the like can be mentioned, but those in a gaseous state at normal temperature and pressure are preferable.
The amount of the chain transfer agent used is usually 1 to 1000 ppm, preferably 1 to 500 ppm, based on the total amount of TFE supplied.

In the production of the PTFE polymer, a saturated hydrocarbon having 12 or more carbon atoms, which is substantially inert to the reaction and becomes liquid under the reaction conditions, is further used as a dispersion stabilizer in the reaction system. It can also be used at 2 to 10 parts by mass with respect to parts by mass. Moreover, you may add ammonium carbonate, an ammonium phosphate, etc. as a buffering agent for adjusting pH during reaction.

When the polymerization of the PTFE polymer is completed, an aqueous dispersion having a solid content concentration of 30 to 70% by mass and an average particle size of 50 to 500 nm can be obtained. Such an aqueous dispersion containing the sulfonyl compound and the fluorine-containing polymer and having an average particle diameter of the fluorine-containing polymer of 50 to 500 nm is also one aspect of the present invention. Moreover, the aqueous dispersion which has the particle | grains which consist of a PTFE polymer of 0.3 micrometer or less microparticle diameter by using the said sulfonyl compound can be obtained. The PTFE polymer at the end of the polymerization has a number average molecular weight of 1,000 to 10,000,000.

The aqueous dispersion of the PTFE polymer can be used for various applications as a fine powder after coagulation, washing and drying. Such a fine powder produced by coagulating the aqueous dispersion is also one aspect of the present invention. When coagulating the aqueous dispersion of the PTFE polymer, the aqueous dispersion obtained by emulsion polymerization such as a polymer latex is usually diluted with water to a polymer concentration of 10 to 20% by mass. In some cases, the pH is adjusted to neutral or alkaline and then stirred more vigorously than stirring during the reaction in a vessel equipped with a stirrer. The coagulation may be performed while adding a water-soluble organic compound such as methanol or acetone, an inorganic salt such as potassium nitrate or ammonium carbonate, or an inorganic acid such as hydrochloric acid, sulfuric acid or nitric acid as a coagulant. The coagulation may be continuously performed using an in-line mixer or the like.

Before or during the coagulation, pigments for coloring and various fillers for improving the mechanical properties are added, so that the pigmented or filler-containing PTFE in which the pigment and the filler are uniformly mixed is added. A polymer fine powder can be obtained.

Drying of the wet powder obtained by coagulating the aqueous dispersion of the PTFE polymer is usually in a state where the wet powder does not flow so much, preferably in a stationary state, while maintaining a vacuum, high frequency, hot air, etc. By means. Friction between powders, particularly at high temperatures, generally has an undesirable effect on fine powder PTFE polymers. This is because particles of this type of PTFE polymer have the property of easily fibrillating even with a small shearing force and losing the original stable particle structure.
The drying is performed at a drying temperature of 10 to 250 ° C, preferably 100 to 200 ° C.

The obtained PTFE polymer fine powder is preferable for molding, and suitable applications include hydraulic and fuel tubes such as aircraft and automobiles, flexible hoses such as chemicals and steam, and wire coating applications. Can be mentioned.

The aqueous dispersion of the PTFE polymer obtained by the above polymerization is also stabilized by adding a nonionic surfactant, and further concentrated. As a composition to which an organic or inorganic filler is added depending on the purpose. It is also preferable to use it for various purposes. The above composition has a non-adhesiveness and a low coefficient of friction when coated on a base material made of metal or ceramics, and has excellent gloss, smoothness, abrasion resistance, weather resistance and heat resistance. It is suitable for coating rolls, cooking utensils, etc., impregnating glass cloth, and the like.

(II) Melt processable resin (1) In the method for producing a fluoropolymer of the present invention, FEP polymerization is usually preferably carried out at a polymerization temperature of 60 to 100 ° C. and a polymerization pressure of 0.7 to 4.5 MpaG. .
The preferable monomer composition (mass%) of FEP is TFE: HFP = (60-95) :( 5-40), More preferably, it is (85-90) :( 10-15). The FEP may further be modified with perfluoro (alkyl vinyl ether) s as a third component and modified within a range of 0.5 to 2% by mass of the total monomers.
In the polymerization of the FEP, the sulfonyl compound can be used in the range of use in the method for producing a fluoropolymer of the present invention, but usually in an amount of 0.0001 to 2% by mass relative to 100% by mass of the aqueous medium. Added.
In the FEP polymerization, cyclohexane, methanol, ethanol, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, etc. are preferably used as the chain transfer agent, and ammonium carbonate, disodium hydrogen phosphate as the pH buffering agent. Etc. are preferably used.

(2) In the method for producing a fluoropolymer of the present invention, polymerization of TFE / perfluoro (alkyl vinyl ether) copolymer such as PFA and MFA is usually performed at a polymerization temperature of 60 to 100 ° C. and a polymerization pressure of 0.7 to 2. It is preferable to carry out at 5 MpaG.
A preferable monomer composition (mol%) of the TFE / perfluoro (alkyl vinyl ether) copolymer is TFE: perfluoro (alkyl vinyl ether) = (95 to 99.7) :( 0.3 to 5), more preferably. Is (98-99.5) :( 0.5-2). Examples of the perfluoro (alkyl vinyl ether), formula: CF ₂ = CFORf ³ (wherein, Rf ³ is a perfluoroalkyl group having 1 to 6 carbon atoms) preferably used those represented by.
In the polymerization of the TFE / perfluoro (alkyl vinyl ether) copolymer, the sulfonyl compound can be used in the range of use in the method for producing a fluoropolymer of the present invention, but is usually based on 100% by mass of the aqueous medium. It is preferable to add in an amount of 0.0001 to 2% by mass.
In the polymerization of the TFE / perfluoro (alkyl vinyl ether) copolymer, it is preferable to use cyclohexane, methanol, ethanol, carbon tetrachloride, chloroform, methylene chloride, methyl chloride, methane, ethane or the like as a chain transfer agent. As a buffering agent, it is preferable to use ammonium carbonate, disodium hydrogen phosphate or the like.

(3) In the method for producing a fluorine-containing polymer of the present invention, ETFE polymerization is usually preferably carried out at a polymerization temperature of 20 to 100 ° C. and a polymerization pressure of 0.5 to 0.8 MPaG.
A preferred monomer composition (mol%) of ETFE is TFE: ethylene = (50 to 99) :( 50 to 1). As the ETFE, a third monomer may be used and modified within a range of 0 to 20% by mass of the total monomers. Preferably, TFE: ethylene: third monomer = (70 to 98) :( 30 to 2) :( 4 to 10). As the third monomer, perfluorobutylethylene, perfluorobutylethylene, 2,3,3,4,4,5,5-heptafluoro-1-pentene (CH ₂ ═CFCF ₂ CF ₂ CF ₂ H), 2-trifluoromethyl-3,3,3-trifluoropropene ((CF ₃ ) ₂ C═CH ₂ ) is preferred.
In the polymerization of ETFE, the sulfonyl compound can be used in the range of use in the method for producing a fluoropolymer of the present invention, but usually in an amount of 0.0001 to 2% by mass relative to 100% by mass of the aqueous medium. Added.
In the above ETFE polymerization, it is preferable to use cyclohexane, methanol, ethanol, carbon tetrachloride, chloroform, methylene chloride, methyl chloride or the like as the chain transfer agent.

(III) Elastomeric polymer In the method for producing a fluorine-containing polymer of the present invention, the polymerization of the elastomeric polymer is carried out by charging pure water and the sulfonyl compound in a pressure-resistant reaction vessel equipped with a stirrer, Thereafter, the monomer is charged, the temperature is set to a predetermined temperature, a polymerization initiator is added, and the reaction is started. Since the pressure decreases as the reaction proceeds, additional monomer is added continuously or intermittently to maintain the initial pressure. When a predetermined amount of monomer is supplied, the supply is stopped, the monomer in the reaction vessel is purged, the temperature is returned to room temperature, and the reaction is terminated. When emulsion polymerization is performed, it is preferable to continuously remove the polymer latex from the reaction vessel.
In particular, when producing a thermoplastic elastomer, as disclosed in the pamphlet of WO00 / 01741, normal polymerization is carried out by once synthesizing the fluorine-containing polymer fine particles at a high concentration and then diluting and further polymerizing. It is also possible to use a method that can increase the final polymerization rate compared to

The polymerization of the elastomeric polymer is appropriately selected from the viewpoints of physical properties of the target polymer and control of the polymerization rate. The polymerization temperature is usually -20 to 200 ° C, preferably 5 to 150 ° C, and the polymerization pressure is usually normal. It is carried out at 0.5 to 10 MPaG, preferably 1 to 7 MPaG. Moreover, it is preferable to maintain pH in a polymerization medium normally at 2.5-9 using the pH adjuster etc. which are mentioned later by a well-known method etc.

Examples of the monomer used for the polymerization of the elastomeric polymer include, in addition to vinylidene fluoride, fluorine-containing ethylenically unsaturated monomers having at least the same number of fluorine atoms as carbon atoms and capable of copolymerizing with vinylidene fluoride. Examples of the fluorine-containing ethylenically unsaturated monomer include trifluoropropene, pentafluoropropene, hexafluorobutene, and octafluorobutene. Among these, hexafluoropropene is particularly suitable due to the elastomeric properties obtained when it blocks polymer crystal growth. Examples of the fluorine-containing ethylenically unsaturated monomer include trifluoroethylene, TFE, and CTFE. A fluorine-containing monomer having one or two or more chlorine and / or bromine substituents may be used. it can. Perfluoro (alkyl vinyl ether) such as perfluoro (methyl vinyl ether) can also be used. TFE and HFP are preferred for producing elastomeric polymers.
The preferable monomer composition (mass%) of an elastomeric polymer is vinylidene fluoride: HFP: TFE = (20-70) :( 20-60) :( 0-40). Elastomeric polymers of this composition exhibit good elastomeric properties, chemical resistance and thermal stability.

In the polymerization of the elastomeric polymer, the sulfonyl compound can be used in the range of use in the method for producing a fluoropolymer of the present invention, but is usually 0.0001 to 2% by mass relative to 100% by mass of the aqueous medium. Add in the amount of.

In the polymerization of the elastomeric polymer, a known inorganic radical polymerization initiator can be used as the polymerization initiator. Examples of the inorganic radical polymerization initiator include conventionally known water-soluble inorganic peroxides such as sodium, potassium and ammonium persulfates, perphosphates, perborates, percarbonates and permanganates. Useful. The radical polymerization initiator further includes a reducing agent such as sodium, potassium or ammonium sulfite, bisulfite, metabisulfite, hyposulfite, thiosulfate, phosphite or hypophosphite. Or by a metal compound that is easily oxidized, such as a ferrous salt, a cuprous salt, or a silver salt. A suitable inorganic radical polymerization initiator is ammonium persulfate, and it is more preferred to use it in a redox system with ammonium persulfate and sodium bisulfite.
The concentration of the polymerization initiator added is appropriately determined depending on the molecular weight of the target fluorine-containing polymer and the polymerization reaction rate, but is 0.0001 to 10% by mass, preferably 0.01% with respect to 100% by mass of the total amount of monomers. Set to an amount of ~ 5% by weight.

In the polymerization of the elastomeric polymer, a known chain transfer agent can be used, but in the polymerization of PVDF, a hydrocarbon, ester, ether, alcohol, ketone, chlorine compound, carbonate, or the like is used. In the thermoplastic elastomer, hydrocarbons, esters, ethers, alcohols, chlorine compounds, iodine compounds, and the like can be used. Among them, acetone and isopropyl alcohol are preferable for the polymerization of PVDF, and isopentane, diethyl malonate and ethyl acetate are preferable for the polymerization of the thermoplastic elastomer from the viewpoint that the reaction rate is difficult to decrease, and I (CF ₂ ) ₄ I , I (CF ₂ ) ₆ I, ICH ₂ I and the like are preferred from the viewpoint that they can be iodinated at the polymer terminal and can be used as a reactive polymer.
The amount of the chain transfer agent used is usually 0.5 × 10 ^{−3 to} 5 × 10 ⁻³ mol%, preferably 1.0 × 10 ^{−3 to} 3.5 × 10, based on the total amount of monomers supplied. ^-3 mol% is preferred.

In the polymerization of the elastomeric polymer, paraffin wax or the like can be preferably used as an emulsion stabilizer in the polymerization of PVDF, and in the polymerization of a thermoplastic elastomer, phosphate, sodium hydroxide, hydroxylation can be used as a pH regulator. Potassium etc. can be used preferably.

The elastomeric polymer obtained by the method for producing a fluoropolymer of the present invention has a solid content concentration of 10 to 40% by mass and an average particle size of 0.03 to 1 μm, preferably 0.05 when polymerization is completed. ˜0.5 μm and a number average molecular weight of 1,000 to 2,000,000.

The elastomeric polymer obtained by the method for producing a fluoropolymer of the present invention is suitable for rubber molding processing by adding, concentrating, etc., a dispersion stabilizer such as a hydrocarbon surfactant, if necessary. It can be a dispersion. The dispersion is processed by adjusting pH, coagulation, heating, and the like. Each process is performed as follows.

The pH adjustment is performed by adding a mineral acid such as nitric acid, sulfuric acid, hydrochloric acid or phosphoric acid and / or a carboxylic acid having 5 or less carbon atoms and having a pK = 4.2 or less to make the pH 2 or less.
The coagulation is performed by adding an alkaline earth metal salt. Examples of the alkaline earth metal salts include nitrates, chlorates and acetates of calcium or magnesium.
Either the pH adjustment or the coagulation may be performed first, but the pH adjustment is preferably performed first.
After each operation, washing is performed with the same volume of water as the elastomer to remove a small amount of impurities such as buffer solution and salt existing in the elastomer, and drying is performed. Drying is usually performed at about 70 to 200 ° C. while circulating air at a high temperature in a drying furnace.

The fluorine-containing polymer is usually in a concentration of 10 to 50% by mass of the aqueous dispersion obtained by performing the polymerization. In the aqueous dispersion, the preferred lower limit of the concentration of the fluoropolymer is 10% by mass, the more preferred lower limit is 15% by mass, the preferred upper limit is 40% by mass, the more preferred upper limit is 35% by mass, and the still more preferred upper limit is 30% by mass. It is.

The aqueous dispersion obtained by performing the above polymerization may be concentrated or dispersion-stabilized to form a dispersion, or as a powder or other solid material obtained by collecting and drying by coagulation or aggregation. Also good.

The sulfonyl compound can also be suitably used as a dispersant for dispersing a fluorine-containing polymer obtained by polymerization in an aqueous medium.

The aqueous dispersion of the present invention contains particles made of a fluorine-containing polymer, the sulfonyl compound, and an aqueous medium. The aqueous dispersion is one in which particles made of a fluorine-containing polymer are dispersed in an aqueous medium in the presence of the sulfonyl compound.

It is preferable that the said sulfonyl compound is 0.0001-15 mass% of the aqueous dispersion of this invention. If it is less than 0.0001% by mass, the dispersion stability may be inferior. If it exceeds 15% by mass, there is no dispersion effect commensurate with the abundance and it is not practical. The more preferable lower limit of the sulfonyl compound is 0.001% by mass, the more preferable upper limit is 10% by mass, and the still more preferable upper limit is 2% by mass.

The aqueous dispersion of the present invention comprises an aqueous dispersion obtained by performing the above-described polymerization, a dispersion obtained by concentrating or dispersing the aqueous dispersion, and a powder comprising a fluoropolymer. Any of those dispersed in an aqueous medium in the presence of the sulfonyl compound may be used.

As the method for producing the aqueous dispersion of the present invention, the aqueous dispersion obtained by the polymerization is contacted with an anion exchange resin in the presence of a nonionic surfactant, and the step (I) The aqueous dispersion obtained in step (II) can be produced by the step (II) in which the solid content concentration is 30 to 70% by mass with respect to 100% by mass of the aqueous dispersion. A method for producing such a purified aqueous dispersion is also one aspect of the present invention. The nonionic surfactant is not particularly limited, and examples thereof include those described above. Although the said anion is not specifically limited, A well-known thing can be used. Moreover, a well-known method can be used for the method made to contact with the said anion exchange resin.

A known method is employed as the concentration method, and examples thereof include phase separation, electric concentration, and ultrafiltration. In the concentration, the fluorine-containing polymer concentration can be concentrated to 30 to 70% by mass depending on the application. Concentration may impair dispersion stability. In that case, a dispersion stabilizer may be further added. As the dispersion stabilizer, the sulfonyl compound and other various surfactants may be added. Examples of the various dispersion stabilizers include nonionic surfactants such as polyoxyalkyl ether, particularly polyoxyethylene alkylphenyl ether (for example, Triton X-100 (trade name) manufactured by Rohm & Haas), Polyoxyethylene isotridecyl ether (for example, Neugen TDS80C (trade name) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Leocor TD90D (trade name) manufactured by Lion, Genapol X080 (trade name) manufactured by Clariant), polyoxyethylene ether However, it is not limited to these.

The total amount of the dispersion stabilizer is 0.5 to 20% by mass with respect to the solid content of the dispersion. If it is less than 0.5% by mass, the dispersion stability may be inferior. If it exceeds 20% by mass, there is no dispersion effect commensurate with the abundance and this is not practical. A more preferable lower limit of the dispersion stabilizer is 2% by mass, and a more preferable upper limit is 12% by mass.

The aqueous dispersion obtained by carrying out the polymerization can also be prepared as an aqueous dispersion having a long pot life by subjecting it to a dispersion stabilization treatment without concentrating depending on the application. Examples of the dispersion stabilizer used include the same as those described above.

The use of the aqueous dispersion of the present invention is not particularly limited, and it is applied as it is as an aqueous dispersion, applied on a substrate, dried, and then fired as necessary; non-woven fabric, resin molded product After impregnating and drying a porous support such as glass, preferably by calcination; after coating and drying on a substrate such as glass, the substrate is immersed in water as necessary to peel off the substrate Examples thereof include cast film formation comprising obtaining a thin film, and examples of these applications include aqueous dispersion paints, electrode binders, electrode water repellents, and the like.

The aqueous dispersion of the present invention can be blended with known pigments, thickeners, dispersants, antifoaming agents, antifreeze agents, film forming aids, or other polymer compounds. It can be combined and used as a water-based paint for coating.

（式中Ｒｆは、Ｈ、炭素数が３〜６のフルオロアルキル基を示し、ｍは０または１を示し、Ｙはカルボキシル基又はスルホン酸基、及び、その塩を示す。）で表されるスルホニル化合物を回収し、精製する工程を含むことを特徴とする再生スルホニル化合物の製造方法でもある。 The present invention also provides the following general formula (I) from at least one component selected from the wastewater generated by the coagulation described above, the wastewater generated by washing, and the off-gas generated in the drying step.

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). It is also a method for producing a regenerated sulfonyl compound, comprising a step of recovering and purifying the sulfonyl compound.

The method for recovering and purifying the sulfonyl compound from the wastewater generated by the coagulation, the wastewater generated by the washing, and the off-gas generated in the drying step is not particularly limited. It can be adopted as it is.

Since the method for producing a fluoropolymer of the present invention has the above-described configuration, it is possible to efficiently produce a fluoropolymer having a very small amount of surfactant in the resin, little coloring, and good physical properties. In addition, since the aqueous dispersion of the present invention has the above-described configuration, a fluoropolymer can be stably present, and a molded product and a coating film of a fluoropolymer with less physical properties and good physical properties are provided. be able to.

Next, although this invention is demonstrated based on a manufacture example and an Example, this invention is not limited only to this manufacture example and an Example.

Synthesis example 1
C ₆ H ₅ S (═O) ₂ CF ₂ COOH (Phenylsulfodifluoroacetic Acid) was synthesized by the method described in Heteroatom Chemistry, Volume 3, Number 3, 1992. This acid was neutralized with aqueous ammonia to make a 10% aqueous solution, and then lyophilized to obtain a white powder of ammonium salt of phenyldifluoroacetic acid.

Example 1 Preparation of PTFE Latex [1]
A stainless steel autoclave with a stirring blade with an internal volume of 3 L was charged with 1.5 L of deionized water, 60 g of paraffin wax (melting point 60 ° C.), and 0.75 g of the emulsifier obtained in Synthesis Example 1, and the inside of the system was TFE Replaced. TFE was injected so that the internal temperature was 70 ° C. and the internal pressure was 0.78 MPa, and 3.75 g of a 1% by mass ammonium persulfate [APS] aqueous solution was charged to initiate the reaction. As the polymerization proceeded, the pressure in the polymerization system decreased, so TFE was continuously added to keep the internal pressure at 0.78 MPa and the reaction was continued. After 5.2 hours from the start of polymerization, TFE was purged to stop the polymerization. The solid content concentration of this aqueous dispersion was 6.4% by mass, the standard specific gravity was 2.225, and the average primary particle size of the fluoropolymer was 281 nm.

Solid content concentration: It was determined from the decrease in mass when the obtained aqueous dispersion was dried at 150 ° C. for 1 hour.
Standard specific gravity (SSG): Measured according to ASTM D-1457-69.
Average primary particle diameter (PTFE): Based on a calibration curve of the transmittance of 550 nm projection light per unit length and the average particle diameter determined by electron micrograph, diluted to a solid content concentration of about 0.02% by mass. Thus, it was indirectly determined from the transmittance.

The sulfonyl compound of the present invention can be suitably used as a surfactant in emulsion polymerization of a fluorine-containing polymer. Further, the present invention provides a production method capable of suitably producing the sulfonyl compound, a surfactant comprising the sulfonyl compound, a production method of a fluoropolymer, an aqueous dispersion, a production method of the aqueous dispersion, Provided are a fine powder and a method for producing a regenerated sulfonyl compound.

Claims (7)

The following general formula (I)

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). A surfactant comprising a sulfonyl compound. The following general formula (I)

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). A method for producing a fluorinated polymer, comprising a step of polymerizing a fluorinated monomer in an aqueous medium containing a sulfonyl compound. The method for producing a fluoropolymer according to claim 2, wherein the content of the sulfonyl compound is 0.0001 to 2% by mass with respect to 100% by mass of the aqueous medium. The following general formula (I)

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). An aqueous dispersion containing a sulfonyl compound and a fluorine-containing polymer,
An aqueous dispersion, wherein the fluoropolymer has an average particle size of 50 to 500 nm. A step (I) of bringing the aqueous dispersion according to claim 4 into contact with an anion exchange resin in the presence of a nonionic surfactant, and the aqueous dispersion obtained in step (I) in the aqueous dispersion A method for producing a purified aqueous dispersion comprising a step (II) of concentrating so that a solid content concentration is 30 to 70% by mass with respect to 100% by mass of an aqueous dispersion. A fine powder produced by coagulating the aqueous dispersion according to claim 4. The following general formula (I) is selected from at least one component selected from waste water generated by coagulation according to claim 6, waste water generated by washing, and off-gas generated in a drying step.

(Wherein Rf represents H, a fluoroalkyl group having 3 to 6 carbon atoms, m represents 0 or 1, Y represents a carboxyl group or a sulfonic acid group, and a salt thereof). A method for producing a regenerated sulfonyl compound, comprising a step of recovering and purifying the sulfonyl compound.