JP5082212B2 - Method for producing fluoroelastomer - Google Patents

Description

  The present invention relates to a method for producing a fluoroelastomer capable of stably and efficiently separating a fluoroelastomer from a polymerized fluoroelastomer dispersion.

  Fluoroelastomer exhibits excellent chemical resistance, solvent resistance, and heat resistance, so it can be used as a raw material for sealing materials used under harsh conditions, such as the automotive industry, semiconductor industry, and chemical industry. Used in

  These fluoroelastomers are produced by emulsion polymerization or suspension polymerization of fluoroolefin. Usually, a surfactant is used in the emulsion polymerization method. However, as the amount of the surfactant used increases, the number of polymer particles generated at the initial stage of the emulsion polymerization increases, and the polymerization rate increases. Production efficiency is improved. However, when a large amount of surfactant is used, after the completion of the polymerization reaction, when the unreacted monomer is recovered, the dispersion is foamed, the dispersion is accompanied by the recovery line, and the polymer to the monomer recovery device tends to be mixed. is there. Therefore, it has been desired to develop a method for producing a fluoroelastomer that can be efficiently polymerized in the presence of a small amount of a surfactant and that does not adversely affect various physical properties of the fluoroelastomer.

  Furthermore, the dispersion obtained by emulsion polymerization is usually a state in which polymer particles of several hundred nm are emulsified and dispersed, and by adding a metal salt such as aluminum sulfate and applying mechanical shearing force, the dispersion is about several millimeters. In the case of a dispersion produced with a small amount of a surfactant, crumbs are agglomerated, but there are frequent problems that the crumb diameter is too large or secondary flocculation between crumbs occurs and the mixer is clogged. .

  A method for obtaining a PTFE fine powder by co-coagulating an aqueous dispersion of a filler and an aqueous dispersion of polytetrafluoroethylene (PTFE) using an anionic surfactant is disclosed (for example, see Patent Document 1). Yes. However, in this method, the hydrophilic filler and the hydrophobic PTFE are uniformly mixed, and the problem at the time of coagulation such as clogging of the mixer is not solved.

  Therefore, there is currently no method for solving such problems.

Japanese Patent Laid-Open No. 56-115326

  The present invention provides a method for producing a fluoroelastomer capable of stably and efficiently separating the fluoroelastomer from a dispersion of a polymerized fluoroelastomer.

  That is, the present invention relates to a method for producing a fluoroelastomer comprising a step of adding a surfactant to an aqueous dispersion of a fluoroelastomer obtained by emulsion polymerization and coagulating.

（式中、Ｒ¹は、フッ素原子を含んでいてもよいアルキル基またはアルケニル基であり、Ｒ²、Ｒ³は、それぞれ同じであっても異なっていてもよく、フッ素原子、水素原子、またはフッ素原子を含んでいてもよいアルキル基もしくはアルケニル基であって、Ｒ⁴はフッ素原子を含んでいてもよいアルキレン基もしくは不飽和結合を有するアルキレン基、または、直接結合であって、Ｒ¹〜Ｒ⁴には酸素原子を含んでいてもよく、Ｒ¹〜Ｒ³の合計炭素数が２〜２５であり、Ｌ^-は−ＳＯ₃ ^-、−ＯＳＯ₃ ^-、−ＰＯ₃ ^-、−ＯＰＯ₃ ^-または−ＣＯＯ^-であらわされる基であり、Ｍ⁺は１価のカチオンである）で示される界面活性剤であることが好ましい。 The surfactant added to the aqueous dispersion is represented by the general formula (1):

(In the formula, R ¹ is an alkyl group or an alkenyl group which may contain a fluorine atom, and R ² and R ³ may be the same or different, and each represents a fluorine atom, a hydrogen atom, or An alkyl group or an alkenyl group which may contain a fluorine atom, wherein R ⁴ is an alkylene group which may contain a fluorine atom or an alkylene group having an unsaturated bond, or a direct bond, wherein R ¹ to R ⁴ may contain an oxygen atom, R ^{1 to} R ^{3 have} a total carbon number of 2 to 25, and L ⁻ represents —SO ₃ ⁻ , —OSO ₃ ⁻ , —PO ₃ ⁻ , —OPO _3. ^- or -COO ^- a group represented by is preferably M ⁺ is a surfactant represented by a is) a monovalent cation.

  It is preferable that the surfactant added to the aqueous dispersion is a fluorine-containing surfactant.

（式中、Ｒ⁵は、アルキル基またはアルケニル基であり、ｎは１以上の整数であり、Ｍ⁺は１価のカチオンである）で示される界面活性剤であることが好ましい。 The surfactant added to the aqueous dispersion is represented by the general formula (2):

(Wherein R ⁵ is an alkyl group or an alkenyl group, n is an integer of 1 or more, and M ⁺ is a monovalent cation).

（式中、Ｒ⁶、Ｒ⁷は、アルキル基またはアルケニル基であり、Ｍ⁺は１価のカチオンである）で示される界面活性剤であることが好ましい。 The surfactant added to the aqueous dispersion is represented by the general formula (3):

(Wherein R ⁶ and R ⁷ are an alkyl group or an alkenyl group, and M ⁺ is a monovalent cation).

  According to the present invention, polymerization can be performed with high production efficiency in the presence of a small amount of a surfactant, and a surfactant is further added to an aqueous dispersion of a fluoroelastomer obtained by emulsion polymerization. Thus, the fluoroelastomer can be separated efficiently. Since the polymerization is carried out in the presence of a small amount of a surfactant, a fluoroelastomer can be produced without deteriorating various physical properties such as water resistance.

  The present invention relates to a method for producing a fluoroelastomer comprising a step of further coagulating by adding a surfactant to an aqueous dispersion of a fluoroelastomer obtained by emulsion polymerization.

  In the present invention, the fluoroelastomer is not particularly limited, but a copolymer of two or more fluoroolefin monomers or a copolymer of a fluoroolefin monomer and a non-fluoroolefin monomer can be used. .

などのパーフルオロオレフィンモノマー；クロロトリフルオロエチレン（ＣＴＦＥ）、ビニリデンフルオライド（ＶｄＦ）、トリフルオロエチレン、フッ化ビニル、トリフルオロプロピレン、ペンタフルオロプロピレン、テトラフルオロプロピレン、ヘキサフルオロイソブテンなどの非パーフルオロオレフィンモノマーがあげられる。ＰＡＶＥとしてはパーフルオロ（メチルビニルエーテル）（ＰＭＶＥ）、パーフルオロ（エチルビニルエーテル）（ＰＥＶＥ）、パーフルオロ（プロピルビニルエーテル）（ＰＰＶＥ）などがあげられる。 Examples of fluoroolefin monomers include tetrafluoroethylene (TFE), hexafluoropropylene (HFP), perfluoro (alkyl vinyl ether) (PAVE),

Non-perfluoroolefin monomers such as chlorotrifluoroethylene (CTFE), vinylidene fluoride (VdF), trifluoroethylene, vinyl fluoride, trifluoropropylene, pentafluoropropylene, tetrafluoropropylene, hexafluoroisobutene Examples include olefin monomers. Examples of PAVE include perfluoro (methyl vinyl ether) (PMVE), perfluoro (ethyl vinyl ether) (PEVE), perfluoro (propyl vinyl ether) (PPVE), and the like.

（式中、Ｙ¹は、−ＯＨ、−ＣＯＯＨ、−ＳＯ₂Ｆ、−ＳＯ₃Ｍ¹（Ｍ¹は水素原子、ＮＨ₄基またはアルカリ金属）、カルボン酸塩、アルコキシカルボニル基（−ＣＯＯＲ⁸、Ｒ⁸は１価の炭化水素基）、エポキシ基またはシアノ基、Ｘ¹およびＸ²は同じかまたは異なりいずれも水素原子またはフッ素原子、Ｒ_fは炭素数０〜４０の２価の含フッ素アルキレン基または炭素数０〜４０のエーテル結合を含有する２価の含フッ素アルキレン基を表わす）があげられ、具体例としては、たとえば Also, functional group-containing fluoroolefin monomers can be used. As the functional group-containing fluoroolefin, for example, the general formula (4):

Wherein Y ¹ is —OH, —COOH, —SO ₂ F, —SO ₃ M ¹ (M ¹ is a hydrogen atom, NH ₄ group or alkali metal), carboxylate, alkoxycarbonyl group (—COOR ⁸ , R ⁸ is a monovalent hydrocarbon group), an epoxy group or a cyano group, X ¹ and X ² are the same or different, and each is a hydrogen atom or a fluorine atom, R _f is a divalent fluorine containing 0 to 40 carbon atoms An alkylene group or a divalent fluorine-containing alkylene group containing an ether bond having 0 to 40 carbon atoms).

などがあげられる。

Etc.

  In addition, as a non-perfluoroolefin monomer, an iodine-containing monomer such as perfluoro (6,6-dihydro-6-iodo-3-oxamer described in JP-B-5-63482 and JP-A-62-12734 can be used. An iodate of perfluorovinyl ether such as -1-hexene) or perfluoro (5-iodo-3-oxa-1-pentene) can also be copolymerized.

  Examples of non-fluoroolefin monomers include α-olefin monomers having 2 to 10 carbon atoms such as ethylene (ET), propylene, butene, and pentene; methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, butyl vinyl ether, and the like. And alkyl vinyl ethers in which the alkyl group has 1 to 20 carbon atoms.

  Among these, a copolymer composed of VdF and HFP or a copolymer composed of VdF, HFP and TFE is preferable for the purpose of producing a fluoroelastomer.

  In addition, the composition of the fluoroelastomer obtained at this time is preferably such that the VdF: HFP is 90:10 to 60:40, more preferably 85:15 to 70:30, and tetrafluoroethylene. It is preferable that 0-40 mol% is included, and 0-30 mol% is more preferable.

  In the present invention, the surfactant used in emulsion polymerization is preferably a fluorine-containing surfactant from the viewpoint of coloring of the resulting fluoroelastomer.

As the fluorine-containing surfactant, CH ₂ ═CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ , ammonium perfluorooctanoate, F (CF ₂ ) ₇ COO ⁻ M ⁺ , F (CF ₂ ) ₈ COO ⁻ M ⁺ , CF ₃ CF ₂ CF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , CF ₃ CF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , CF ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , H (CF ₂ CF ₂ ) ₂ CH ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , H (CF ₂ ) ₆ COO ⁻ M ⁺ , H (CF ₂ ) ₇ COO ⁻ M ⁺ , H (CF ₂ ) ₈ COO ⁻ M ⁺ , C ₆ F ₁₃ CH ₂ CH ₂ SO ₃ ⁻ M ⁺ , F (CF ₂ CF ₂ ) ₂ CH ₂ CH ₂ SO _{3 ^{- M +, F (CF 2}} CF 2) 3 CH 2 CH 2 SO 3 - M +, F (CF 2 CF 2) 4 ^{_{CH 2 CH 2 SO 3 - M}} +, F (CF 2 CF 2) 2 CH 2 CH 2 SO 4 - M +, F (CF 2 CF 2) 3 CH 2 CH 2 SO 4 - M +, F (CF 2 CF ₂ ) ₄ CH ₂ CH ₂ SO ₄ ^- M ⁺ (in these formulas, M ⁺ is a monovalent cation). These surfactants may be used alone or in combination of two or more.

  Examples of the monovalent cation include lithium ion, sodium ion, potassium ion, rubidium ion, cesium ion, and ammonium ion, and sodium ion and ammonium ion are preferable from the economical viewpoint.

  The amount of the surfactant added during polymerization is preferably 10 to 10,000 ppm, more preferably 25 to 1000 ppm, based on the total amount of water. When the amount of the surfactant used is less than 10 ppm, the effect as a surfactant is small, the number of generated particles decreases, and when it exceeds 10,000 ppm, the dispersion tends to aggregate due to the surfactant. There is. The surfactant may be used in combination with other surfactants.

  Examples of the surfactant that can be used in combination include a reactive surfactant composed of a compound having a radical polymerizable unsaturated bond and a hydrophilic group in the molecule. When the reactive surfactant is present in the reaction system during polymerization, it can constitute a part of the polymer chain of the polymer.

  As the reactive surfactant, for example, compounds described in JP-A-8-67795 can be used.

  The method of emulsion polymerization performed in the present invention is not particularly limited, but the initial polymerization of seed polymerization, that is, production polymerization of seed particles, is possible in that the number of particles can be increased even if the surfactant in the obtained polymer is the same amount. Can be suitably applied. Also, the seed polymerization method is not particularly limited, and may be a known method.

  As the stirring means, for example, an anchor blade, a turbine blade, an inclined blade, or the like can be used. However, stirring with a large blade called a full zone or max blend is preferable from the viewpoint of good monomer diffusion and polymer dispersion stability. The stirring device may be a horizontal stirring device or a vertical stirring device.

  The polymerization temperature is not particularly limited, and an optimum temperature is adopted according to the kind of the polymerization initiator. However, if it becomes too high, the monomer density in the gas phase portion may easily decrease, or a polymer branching reaction may occur, and the desired copolymer may not be obtained. Preferably it is 40-120 degreeC, More preferably, you may be 50-100 degreeC.

  The monomer may be supplied continuously or sequentially.

  As the polymerization initiator, oil-soluble peroxides can be used, but these typical oil-soluble initiators such as diisopropyl peroxydicarbonate (IPP) and di-n-propyl peroxydicarbonate (NPP) These peroxycarbonates have a risk of explosion and the like, are expensive, and have a problem that scales tend to adhere to the wall of the polymerization tank during the polymerization reaction. In order to further reduce the compression set of the fluoropolymer, it is preferable to use a water-soluble radical polymerization initiator. Preferred examples of the water-soluble radical polymerization initiator include persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, ammonium percarbonate, potassium salt, sodium salt, and the like. Particularly, ammonium persulfate and potassium persulfate are used. preferable.

  The addition amount of the polymerization initiator is not particularly limited, but it is added all at once in the initial stage of polymerization, sequentially or continuously, such that the polymerization rate is not significantly reduced (for example, several ppm to water concentration). do it. The upper limit is a range in which the heat of polymerization reaction can be removed from the surface of the apparatus.

  In the production method of the present invention, a molecular weight regulator or the like may be further added. The molecular weight modifier may be added all at once in the initial stage, or may be added continuously or dividedly.

Examples of the molecular weight regulator include esters such as dimethyl malonate, diethyl malonate, methyl acetate, ethyl acetate, butyl acetate, dimethyl succinate, isopentane, isopropanol, acetone, various mercaptans, carbon tetrachloride, cyclohexane, mono Iodomethane, 1-iodomethane, 1-iodopropane, isopropyl iodide, diiodomethane, 1,2-diiodomethane, 1,3-diiodopropane, 1,3-diiodoperfluoropropane, 1,3-diiodo-2- Chloroperfluoropropane, 1,4-diiodoperfluorobutane, 1,5-diiodo-2,4-dichloroperfluoropentane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,12-diiodoperfluorododecane 1,16 diiodoperfluoro hexadecane, diiodomethane, 1,2-diiodoethane, 1,3-diiodo -n- _{propane, CF 2 Br 2, BrCF 2} CF 2 Br, CF 3 CFBrCF 2 Br, CFClBr 2, BrCF 2 CFClBr, CFBrClCFClBr, BrCF ₂ CF ₂ CF ₂ Br, BrCF ₂ CFBrOCF ₃ , 1-bromo-2-iodoperfluoroethane, 1-bromo- ₃ -iodoperfluoropropane, 1-bromo-4-iodoperfluorobutane, 2-bromo-3-iodoperfluorobutane, 3-bromo-4-iodoperfluorobutene-1, 2-bromo-4-iodoperfluorobutene-1, monoiodo-monobromo substitution of benzene, diiodo substitution, And (2-iodoethyl) and (2-bromoe Le) such substituents. These compounds may be used alone, it may be used in combination with one another.

  In addition, a buffering agent or the like may be added as appropriate, but the amount is preferably used within a range not impairing the effects of the present invention.

  The particle size of the aqueous dispersion obtained by the above-described polymerization is preferably 50 to 400 nm, and more preferably 100 to 300 nm. If the particle diameter is less than 50 nm, the number of particles increases, so that a large amount of surfactant tends to be required, and if it exceeds 400 nm, the stability of the particles tends to decrease and aggregation and adhesion tend to occur.

  The Mooney viscosity (1 + 10 100 ° C.) of the aqueous dispersion obtained by polymerization is preferably 40 to 120, more preferably 45 to 80. When the Mooney viscosity is less than 40, the cohesive crumb has increased tackiness, and there is a tendency for more severe secondary flocculation and adhesion to occur in the coagulator, which makes it difficult to handle. Since it is an elastomer, its melt flowability is poor and its handling in the drying process tends to be difficult.

  The production method of the present invention includes a step of further adding a surfactant to an aqueous dispersion of a fluoroelastomer obtained by emulsion polymerization. By adding a surfactant, it is possible to prevent secondary flocculation of the crumb in the coagulation process, stably and efficiently separate the fluoroelastomer and moisture, and by drying the fluoroelastomer Can be obtained.

  The surfactant added to the aqueous dispersion may be the same as the surfactant added before polymerization, or may be a different type of surfactant.

（式中、Ｒ¹は、フッ素原子を含んでいてもよいアルキル基またはアルケニル基であり、Ｒ²、Ｒ³は、それぞれ同じであっても異なっていてもよく、フッ素原子、水素原子、またはフッ素原子を含んでいてもよいアルキル基もしくはアルケニル基であって、Ｒ⁴はフッ素原子を含んでいてもよいアルキレン基もしくは不飽和結合を有するアルキレン基、または、直接結合であって、Ｒ¹〜Ｒ⁴には酸素原子を含んでいてもよく、Ｒ¹〜Ｒ³の合計炭素数が２〜２５であり、Ｌ^-は−ＳＯ₃ ^-、−ＯＳＯ₃ ^-、−ＰＯ₃ ^-、−ＯＰＯ₃ ^-または−ＣＯＯ^-であらわされる基であり、Ｍ⁺は１価のカチオンである）で示される界面活性剤が好ましい。 As the surfactant to be added to the aqueous dispersion, the above surfactants can also be suitably used. In addition, the general formula (1):

(In the formula, R ¹ is an alkyl group or an alkenyl group which may contain a fluorine atom, and R ² and R ³ may be the same or different, and each represents a fluorine atom, a hydrogen atom, or An alkyl group or an alkenyl group which may contain a fluorine atom, wherein R ⁴ is an alkylene group which may contain a fluorine atom or an alkylene group having an unsaturated bond, or a direct bond, wherein R ¹ to R ⁴ may contain an oxygen atom, R ^{1 to} R ^{3 have} a total carbon number of 2 to 25, and L ⁻ represents —SO ₃ ⁻ , —OSO ₃ ⁻ , —PO ₃ ⁻ , —OPO _3. ^- or -COO ^- a group represented by, M ⁺ is surfactant represented by the a) monovalent cations are preferred.

The total carbon number of R ^{1 to} R ³ is 2 to 25, preferably 5 to 20, and more preferably 10 to 20. If the total carbon number of R ^{1 to} R ³ exceeds 25, it is difficult to dissolve in water and the concentration in the aqueous phase tends to be unable to be increased.

  The alkyl group or alkenyl group may be linear or branched. For example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group Hexyl group, heptyl group, octyl group, nonyl group, decyl group, 2-ethylhexyl group, vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptanyl group, octenyl group, etc. An oxygen atom such as an oxygen atom constituting a reactive oxygen atom or a carbonyl group may be contained. Moreover, the hydrogen atom of these groups may be a fluorine-containing alkyl group substituted with a fluorine atom or a fluorine-containing alkenyl group.

  Examples of the alkylene group or alkylene group having an unsaturated bond include methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, decylene group, propenylene group, butenylene. Group, a pentenylene group, a heptenylene group, an octenylene group and the like, and these may contain an oxygen atom such as an oxygen atom constituting an ether bond oxygen atom or a carbonyl group. Moreover, the hydrogen atom of these groups may be a fluorine-containing alkylene group substituted with a fluorine atom or a fluorine-containing alkylene group having an unsaturated bond.

L ^{- _{is, -SO 3 -, -OSO 3 -}} , -PO 3 -, -OPO 3 - , or -COO ^- in is a radical _{^{represented, -SO 3 -, -OSO 3 -}} , -COO - is It is more preferable from the viewpoint that even if the surfactant remains in the polymer obtained by coagulating the dispersion, the influence on vulcanization is small.

  Examples of the monovalent cation include lithium ion, sodium ion, potassium ion, rubidium ion, cesium ion, and ammonium ion, and sodium ion and ammonium ion are preferable from the economical viewpoint.

Among the surfactants, R ³ is preferably a hydrogen atom from the viewpoint of high emulsifying power.

  In addition, a fluorine-containing surfactant is preferable because it is highly volatile and hardly remains in the product.

（式中、Ｒ⁵、Ｒ⁶、Ｒ⁷は、アルキル基またはアルケニル基であり、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹は、フッ素原子を含んでいてもよい、アルキル基またはアルケニル基であり、Ｒ¹²〜Ｒ¹⁴は、フッ素原子または酸素原子を含んでいてもよい炭素数１〜１０のアルキル基である。また、ｎ、ｍは１以上の整数であり、Ｍ⁺は１価のカチオンである。 Further, as such surfactants, specifically, general formulas (2), (3), (5) to (12):

Wherein R ⁵ , R ⁶ and R ⁷ are alkyl groups or alkenyl groups, R ⁹ , R ¹⁰ and R ¹¹ are alkyl groups or alkenyl groups which may contain a fluorine atom, ^{12 to} R ¹⁴ are each an alkyl group having 1 to 10 carbon atoms which may contain a fluorine atom or an oxygen atom, n and m are integers of 1 or more, and M ⁺ is a monovalent cation. .

  Examples of these alkyl group, alkenyl group, and monovalent cation include those described above.

More specifically, for example,
Hostapur SAS93 from Clariant Japan KK:

Hightenol PS-06 from Daiichi Kogyo Seiyaku Co., Ltd .:

Hightenol 227L from Daiichi Kogyo Seiyaku Co., Ltd .:

Hightenol NF-13 from Daiichi Kogyo Seiyaku Co., Ltd .:

Neo Haitenol ECL-30S from Daiichi Kogyo Seiyaku Co., Ltd .:

Amitate LS-30 from Daiichi Kogyo Seiyaku Co., Ltd .:

PALEX OT-P from Kao Corporation:

_{CH 2 = CFCF 2 OCF (CF} 3) CF 2 OCF (CF 3) COONH 4, ammonium perfluorooctanoate;
^{_{F (CF 2) 7 COO -}} M +, F (CF 2) 8 COO - M +, CF 3 CF 2 CF 2 OCF (CF 3) CF 2 OCF (CF 3) COO - M +, CF 3 CF 2 OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , CF ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , H (CF ₂ CF ₂ ) ₂ CH ₂ OCF (CF ₃ ) COO ⁻ M ⁺ , H (CF ₂ ) ₆ COO ⁻ M ⁺ , H (CF ₂ ) ₇ COO ⁻ M ⁺ , H (CF ₂ ) ₈ COO ⁻ M ⁺ , C ₆ F ₁₃ CH ₂ CH ₂ SO ₃ ⁻ M ^{_{+, F (CF 2 CF 2}} ) 2 CH 2 CH 2 SO 3 - M +, F (CF 2 CF 2) 3 CH 2 CH 2 SO 3 - M +, F (CF 2 CF 2) 4 CH 2 CH 2 ^{_{SO 3 - M +, F (}} CF 2 CF 2) 2 CH 2 CH 2 SO 4 - M +, F (CF 2 CF 2) 3 CH 2 CH 2 SO 4 - M +, F (CF 2 CF 2) ₄ CH ₂ CH ₂ SO ₄ ^- fluorinated surfactants such as M ^+;
_{CH 3 (CH 2) 10 SO} 3 - M +, CH 3 (CH 2) 11 SO 3 - M +, CH 3 (CH 2) 12 SO 3 - M +, CH 3 (CH 2) 13 SO 3 - M ^{_{+, CH 3 (CH 2)}} 14 SO 3 - M +, CH 3 (CH 2) 10 SO 4 - M +, CH 3 (CH 2) 11 SO 4 - M +, CH 3 (CH 2) 12 SO 4 _{^{- M +, CH 3 (CH}} 2) 13 SO 4 - M +, CH 3 (CH 2) 14 SO 4 - M +, CH 3 (CH 2) 10 COO - M +, CH 3 (CH 2) 11 COO _{^{- M +, CH 3 (CH}} 2) 12 COO - M +, CH 3 (CH 2) 13 COO - M +, CH 3 (CH 2) 14 COO - M + (M is a monovalent cation) carbide, such as Examples include hydrogen surfactants.

  Among these, since the lipophilicity of the hydrophobic group is high and the foaming effect is high, the above-described general formulas (2), (3), (6), (7), and (9) to (12) are shown. Surfactants are preferred, and surfactants represented by general formulas (2) and (3) are more preferred.

  The amount of surfactant added to the aqueous dispersion is preferably 300 to 2000 ppm, more preferably 500 to 1000 ppm, based on the total amount of the fluoroelastomer aqueous dispersion obtained by polymerization. If the amount of the surfactant used is less than 300 ppm, the stability of the coagulated crumb is small and the crumb diameter is large, the amount of uncoagulated components tends to increase, or the adhesion in the coagulator tends to increase. If it exceeds 2000 ppm, the diameter of the coagulated crumb becomes too small, so that clogging of the sieve tends to occur.

  Furthermore, in the present invention, a coagulant may be added in order to separate water and the elastomer by aggregation by salting out. Although the addition method of a coagulant is not specifically limited, It is preferable to include the process of adding a coagulant after adding surfactant.

  The coagulant is not particularly limited as long as it is usually used. For example, sulfuric acid, hydrochloric acid, nitric acid, aluminum sulfate, aluminum chloride, magnesium chloride, calcium chloride, sodium nitrate, potassium alum, etc. Can be given. Among these, aluminum sulfate is preferable.

  The addition amount of the coagulant is preferably 0.2 to 3 parts by weight and more preferably 0.5 to 2 parts by weight with respect to 100 parts by weight of the fluoropolymer obtained by polymerization. If the addition amount of the coagulant is less than 0.2 parts by weight, a sufficient coagulation effect cannot be obtained, so that there is a tendency that a fluoropolymer cannot be obtained efficiently. There is a tendency that a large amount of the coagulant remains in the fluoropolymer obtained even after the process.

  A surfactant is added, and optionally a coagulant is added to separate the fluoropolymer from the water-soluble dispersion. At this time, the concentration of polymer particles remaining in the coagulated water as uncoagulated is determined by the water-soluble dispersion. It is preferably 100 ppm or less, more preferably 20 ppm or less, based on the total amount of water in the liquid. When the amount of unaggregated polymer exceeds 100 ppm, there is a tendency for adhesion and clogging in the line in a later process. In addition, the density | concentration of the polymer particle which remains as unaggregated is so preferable that it is small, and a lower limit is not restrict | limited.

  The coagulation device is not particularly limited, and any commonly used one may be used.

  Next, the present invention will be described with reference to examples, but the present invention is not limited to such examples.

<Mooney viscosity>
JIS K 6300 (1994) using a Mooney viscometer (manufactured by MOON MV2000E ALPHA TECHNOLOGIES) with an L-type rotor and preheating time of 1 minute and measurement time of 10 minutes. ) And measured.

<Emulsified dispersion particle size>
The particle size distribution was measured using a particle size distribution analyzer (Microtrack UPA manufactured by Nikkiso Co., Ltd.).

<Molecular weight>
Measurement was performed using GPC (manufactured by Tosoh Corporation).

<Unaggregated concentration>
About 1 L of the liquid containing uncoagulated is sampled in a 2 L beaker, and the weight is measured (Xg). The mixture was allowed to stand for 3 days to cause the uncoagulated polymer to coagulate and settle, which was dried and weighed (Yg) to determine the uncoagulated concentration (Y / X).

<Composition analysis>
¹⁹ F-NMR (Bruker AC300P type) was used for measurement. However, the TFE-containing polymer was measured using ¹⁹ F-NMR (FX100 type manufactured by JEOL Ltd.).

Production Example 1 (polymerization of seed polymer particles)
A stainless steel autoclave with an internal volume of 1.8 L was charged with 720 g of ion-exchanged water, 290 g of a 10% by weight ammonium perfluorooctanoate aqueous solution, and 0.6 g of diethyl malonate. did. This operation was repeated three times, and 20 g of VdF and 51 g of HFP were charged under reduced pressure, and the temperature was raised to 80 ° C. with stirring. Next, 0.02 g of ammonium persulfate (APS) dissolved in 0.6 g of pure water was injected with nitrogen gas to initiate polymerization. The polymerization pressure was set to 2 MPa, and in order to compensate for the pressure drop during the polymerization, VdF / HFP mixed monomer 78/22 (mol%) was continuously supplied, and polymerization was carried out with stirring. By the end of the polymerization, 215 g of monomer was fed into the tank.

1233 g of an emulsion having a polymer concentration of 18.1% by weight and a number of polymer particles of 1.2 × 10 ¹⁶ particles / g of water was obtained. After 30 minutes, the stirring was stopped and the monomer was released to stop the polymerization.

Production Example 2
A stainless steel autoclave with an internal volume of 50 L was charged with 33.1 kg of pure water and 204 g of an aqueous dispersion of polymer particles produced in Production Example 1, and the system was sufficiently replaced with nitrogen gas and then decompressed. This operation was repeated three times. Under reduced pressure, 4.3 kg of VdF and 14.4 kg of HFP were charged, and the temperature was raised to 80 ° C. with stirring. Then, an aqueous solution obtained by dissolving 193 g of diethyl malonate and 6.0 g of APS in 50 g of water was injected with nitrogen to initiate polymerization. In order to compensate for the pressure drop during the polymerization, VdF / HFP mixed monomer 78/22 (mol%) was supplied by a plunger pump. 8.9 kg of VdF / HFP mixed monomer 78/22 (mol%) was charged into the polymerization tank to complete the polymerization.

When the particle size of the emulsion dispersion obtained by releasing the residual monomer into the atmosphere after completion of the polymerization reaction was measured by UPA, it was 184 nm. The concentration of the emulsified dispersion was measured by evaporating a part of the emulsified dispersion to 26.5%. The ML (1 + 10 100 ° C.) was 45. The composition of the fluoropolymer measured by ¹⁹ F-NMR was VdF / HFP = 78/22 (mol%).

Production Example 3
The polymerization tank with an internal volume of 2500 L is sufficiently replaced with nitrogen gas and decompressed, and then charged with 1500 kg of ion exchange water and 300 g of a 50% aqueous solution of CH ₂ ═CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ , 172 kg of VdF and 549 kg of HFP were charged, the inside of the tank was heated to 80 ° C. while stirring in the system, and left until the pressure became constant. Next, 7.7 kg of diethyl malonate and 4.5 kg of 5 wt% APS were charged to initiate the polymerization reaction. In order to compensate for the pressure drop during the polymerization, VdF / HFP mixed monomer 78/22 (mol%) was supplied by a plunger pump. VdF and HFP were charged to 260 kg and 120 kg, respectively, and the polymerization was completed.

When the particle size of the emulsion dispersion obtained by releasing the residual monomer into the atmosphere after completion of the polymerization reaction was measured by UPA, it was 153 nm. Further, the concentration of the emulsified dispersion was measured by evaporating a part of the emulsified dispersion to dryness and found to be 27.1%. The ML (1 + 10 100 ° C.) was 39. Moreover, the composition of the fluoropolymer measured by ¹⁹ F-NMR was VdF / HFP = 77.7 / 22.3 (mol%).

Production Example 4
A stainless steel autoclave with an internal volume of 3 L was charged with 0.99 kg of pure water and 0.2 g of a 50% aqueous solution of CH ₂ = CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ , and nitrogen gas was sufficient in the system After replacement, the pressure was reduced. This operation was repeated three times, and in a reduced pressure state, VdF, TFE, and HFP were charged in predetermined amounts at a composition ratio of 19/11/70 (mol%), respectively, and the temperature was raised to 80 ° C. with stirring. Next, 1.531 g of octafluoro-1,4-diiodobutane and 0.0236 g of APS (APS) were injected under nitrogen to initiate polymerization. In order to compensate for the pressure drop during the polymerization, 50/30/20 (mol%) of VdF / HFP / TFE mixed monomer was supplied by a plunger pump. An additional 0.0236 g of APS was charged at the timing of 3 hours and 6 hours after the start of polymerization. ₄₀ , 50, 60, 70% with respect to the polymerization amount, 0.1 g of a 50% aqueous solution of CH ₂ = CFCF ₂ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ was added to the polymerization tank Added an additional charge. The polymerization was completed by adding 333 g of VdF / TFE / HFP monomer mixture 50/20/30 (mol%).

The particle size of the obtained emulsified dispersion was measured by UPA and found to be 120 nm. The concentration of the emulsified dispersion was measured by evaporating a part of the emulsified dispersion to 23.5%. The ML (1 + 10 100 ° C.) was 64. The composition of the fluoropolymer measured by ¹⁹ F-NMR was VdF / TFE / HFP = 50/20/30 (mol%).

Example 1
To 30 kg of the emulsified dispersion obtained in Production Example 2, ammonium perfluorooctanoate was added to a concentration of 1000 ppm by weight with respect to water, and adjusted to 40 ° C., and charged into a continuous coagulation apparatus at a rate of 2 kg / min. At the same time, while adjusting an aluminum sulfate aqueous solution with a conductivity of 1.0 mS / cm to a temperature of 50 ° C., a continuous coagulation device was charged to a total of 84 g of aluminum sulfate at a rate of 7 L / min. The emulsion dispersion was crushed and aggregated by stirring at 3600 rpm. At this time, the concentration of polymer particles remaining as uncoagulated in the coagulated water at the coagulator outlet was measured and found to be 100 ppm or less against water. Further, a uniform and small crumb diameter of about 5 to 10 mm was obtained. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 2
Sodium dodecyl sulfate was added to the emulsified dispersion obtained in Production Example 2 to a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 100 ppm or less with respect to water. Further, a uniform and small crumb diameter of about 5 to 10 mm was obtained. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 3
HostapurSAS93 (manufactured by Clariant Japan Co., Ltd., secondary alkane sulfonate sodium salt) was added to the emulsified dispersion obtained in Production Example 2 so as to have a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 100 ppm or less with respect to water. Further, a uniform and small crumb diameter of about 5 to 10 mm was obtained. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 4
Hytenol PS-06 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was added to the emulsified dispersion obtained in Production Example 3 to a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 120 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 5
Hytenol 227L (Daiichi Kogyo Seiyaku Co., Ltd.) was added to the emulsified dispersion obtained in Production Example 3 so as to have a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 190 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 6
Hytenol NF-13 (Daiichi Kogyo Seiyaku Co., Ltd.) was added to the emulsified dispersion obtained in Production Example 3 so as to have a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 160 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 7
Neohytenol ECL-30S (Daiichi Kogyo Seiyaku Co., Ltd.) was added to the emulsified dispersion obtained in Production Example 3 so as to have a concentration of 600 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 43 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 8
Amitate LS-30 (Daiichi Kogyo Seiyaku Co., Ltd.) was added to the emulsified dispersion obtained in Production Example 3 to a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 0 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 9
Sodium tridecyl sulfate was added to the emulsified dispersion obtained in Production Example 3 to a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 0 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 10
HostapurSAS93 (manufactured by Clariant Japan Co., Ltd., secondary alkane sulfonate sodium salt) was added to the emulsified dispersion obtained in Production Example 3 to a concentration of 600 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 100 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 11
Perex OT-P (manufactured by Kao Corporation) was added to the emulsified dispersion obtained in Production Example 3 so as to have a concentration of 500 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 16 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Example 12
To the emulsified dispersion obtained in Production Example 4, ammonium perfluorooctanoate was added to a concentration of 1000 ppm by weight with respect to water. Thereafter, coagulation and evaluation were performed in the same manner as in Example 1. The uncoagulated concentration was 20 ppm with respect to water. Adhesion inside the line mixer of the continuous coagulator was not observed.

Comparative Example 1
While adjusting 30 kg of the emulsified dispersion obtained in Production Example 2 to 40 ° C., it was charged into a continuous coagulation device at a rate of 2 kg / min, and at the same time, an aluminum sulfate aqueous solution having a conductivity of 1.0 mS / cm was heated to 50 ° C. In the continuous coagulation apparatus, a total of 84 g of aluminum sulfate was prepared at a rate of 7 L / min, and the emulsion dispersion was crushed and aggregated by a salting out effect by stirring at 3600 rpm in a line mixer. . At this time, the concentration of polymer particles remaining as uncoagulated in the coagulated water at the coagulator outlet was measured and found to be 2850 ppm relative to water. Moreover, the diameter of the obtained crumb varied in the range of about 1 to 15 mm. In addition, the generated crumbs adhered inside the line mixer of the continuous coagulation device, causing clogging and greatly reducing the efficiency of coagulation.

Claims (4)

A method for producing a fluoroelastomer comprising a step of further coagulating by adding a surfactant to an aqueous dispersion of a fluoroelastomer obtained by emulsion polymerization ,
The surfactant added to the aqueous dispersion is represented by the general formula (1):

(In the formula, R ¹ is an alkyl group or an alkenyl group which may contain a fluorine atom, and R ² and R ³ may be the same or different from each other, and a fluorine atom, a hydrogen atom, or An alkyl group or an alkenyl group which may contain a fluorine atom, wherein R ⁴ is an alkylene group which may contain a fluorine atom or an alkylene group having an unsaturated bond, or a direct bond, wherein R ¹ to R ⁴ may contain an oxygen atom, R ^{1 to} R ^{3 have} a total carbon number of 2 to 25, and L ⁻ represents —SO ₃ ^— , —OSO ₃ ^— , —PO ₃ ^— , —OPO _3. ^- or -COO ^- by a group represented, M ⁺ manufacturing method of the fluoroelastomer is a surfactant represented by a is) a monovalent cation. Surfactant added to the aqueous dispersion, a manufacturing method of the fluoroelastomer of claim 1 Symbol placement is a fluorine-containing surfactant. The surfactant added to the aqueous dispersion is represented by the general formula (2):

(Wherein, R ⁵ is an alkyl or alkenyl group, n is an integer of 1 or more, M ⁺ is a monovalent and is a cation) fluoro according to claim 1 Symbol placement is a surfactant represented by Elastomer production method. The surfactant added to the aqueous dispersion is represented by the general formula (3):

(Wherein, R ^6, R ⁷ is an alkyl or alkenyl group, M ⁺ is a is a monovalent cation) method for producing a fluoroelastomer according to claim 1 Symbol placement is a surfactant represented by.