JP2011173959A - Method for producing fluorine-containing polymer latex - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a fluorine-containing polymer latex having environmental degradability and remarkably reducing the amount of a residual emulsifier. <P>SOLUTION: A fluorine-containing polymer latex is produced by emulsion polymerization of a fluorine-containing monomer by using a perfluoroalkyl alkylphosphonate expressed by general formula C<SB>n</SB>F<SB>2n+1</SB>C<SB>m</SB>H<SB>2m</SB>P(O)(OM<SP>1</SP>)(OM<SP>2</SP>) as an emulsifier (wherein M<SP>1</SP>represents a hydrogen atom, an alkali metal or an ammonium group; M<SP>2</SP>represents an alkali metal or an ammonium salt; n represents an integer of 2 to 6; and m represents an integer of 1 to 3). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a fluorine-containing polymer latex. More specifically, the present invention relates to a method for producing a fluorine-containing polymer latex capable of significantly reducing the amount of residual emulsifier.

Perfluoroalkyl group-containing carboxylic acids (salts) are widely used in emulsion polymerization reactions of fluorine-containing monomers as fluorine-based surfactants that act as emulsifiers. Among these, perfluorooctanoic acid C ₇ F ₁₅ COOH or a salt thereof (collectively referred to as [PFOA]) is known to be a surfactant excellent in monomer emulsification and latex stability.

  However, it has recently been found that perfluorinated chemicals are not easily decomposed in the natural environment, and that the perfluorinated compounds having 8 carbon atoms, represented by PFOA, have extremely strong persistence in the human body. is doing. In addition, PFOA has a high affinity for polymers, and therefore, after the polymer latex obtained by emulsion polymerization is agglomerated, the amount of PFOA attached to the fluoropolymer and the residual amount are large. Reduction is strongly desired.

As a means for imparting environmental degradability to the fluorinated emulsifier, it is conceivable to provide a hydrogenated portion in the perfluorinated hydrophobic group of the surfactant compound. Further, as a means to weaken the environmental persistence of decomposition product, a hydrophobic group in the _{C n F 2n + 1 C p} H 2p C q F 2q - (n, r: 1~7, p: 1 or higher) group Thus, it is considered desirable that the carbon chain has a continuous perfluorinated carbon atom number of less than 8.

Patent Document 1 discloses a general formula.
F (CF ₂ CF ₂ ) _n CH ₂ CH ₂ SO ₃ M (M: monovalent cation)
It is described that a mixture of an aggregate number n of 2 to 8, an average value of 2 to 6 and an aggregate number n of 2 to 6 is used as a dispersant. However, when this perfluoroalkylethanesulfonic acid (salt) is used as the fluorine-containing surfactant, chain transfer occurs during the polymerization reaction, and thus it is inevitable that the resulting polymer has a low molecular weight.

As a hydrogen-containing fluorosurfactant with low chain mobility during polymerization reaction,
Rf (CH ₂ ) _m R′fCOOM
Rf: C _{3 to} C ₈ perfluoroalkyl group or perfluoroalkoxyl group
R′f: C ₁ -C ₄ perfluoroalkylene group
M: NH ₄ , Li, Na, K, H
m: 1-3
Patent Document 2 proposes to use a compound represented by: However, when this compound is used as an emulsifier for the emulsion polymerization of a fluorinated monomer, it is not only inferior to PFOA in terms of monomer emulsification and latex stability, but in the homopolymerization and copolymerization of vinylidene fluoride. In addition, since the micelle solubility of vinylidene fluoride as a monomer is low, the polymerization rate becomes very slow, the stability of the resulting polymer latex is also poor, and precipitates may be observed during the polymerization reaction.

In addition, the hydrogen-containing fluorine-based surfactant Rf (CH ₂ ) _m Rf′COOM described in Patent Document 2 is converted into a free carboxylic acid by alkaline hydrolysis of the corresponding carboxylic acid ester and then reacted with a base. A carboxylate is formed. Alkaline hydrolysis of this carboxylic acid ester is carried out in the presence of an excess amount of alkali, so that the —CH ₂ CF ₂ — group in the molecule is converted to —CH═CF— group by deHF reaction There is also a side reaction in which about several percent of is produced.

  Furthermore, attempts have been made to use fluorinated polyether-based carboxylic acids (salts) as emulsifiers (see Patent Document 3). However, many of these compounds have low solubility in aqueous media and are easy to handle. It is extremely difficult and cleaning after coagulation is not easy. In particular, among the polyether carboxylic acid (salt) emulsifiers, those having side chains or those having long chains have such a tendency.

  Furthermore, polyether-based carboxylic acid (salt) is easy to foam, not only is the handling of the latex obtained by the polymerization reaction not easy, but there is also a description that the amount of aggregate in the latex is larger than that of PFOA ( (See Patent Document 3).

USP 4,380,618 Japanese Patent Laid-Open No. 10-212261 USP 3,271,341 JP 58-210096 Japanese Patent Laid-Open No. 11-80271

  An object of the present invention is to provide a method for producing a fluorine-containing polymer latex that is environmentally degradable and can significantly reduce the amount of residual emulsifier.

The object of the present invention is to provide a general formula
C _n F _{2n + 1} C _m H _2m P (O) (OM ¹ ) (OM ² )
Wherein M ¹ is a hydrogen atom, an alkali metal or an ammonium group, M ² is an alkali metal or an ammonium salt, n is an integer of 2 to 6, and m is an integer of 1 to 3. This is achieved by emulsion polymerization of a fluorine-containing monomer using a perfluoroalkylalkylphosphonate as an emulsifier to produce a fluorine-containing polymer latex.

In the fluorine-containing polymer latex according to the present invention, since the perfluoroalkylalkylphosphonate is used as an emulsifier, the following effects are obtained.
(1) Since it has a CH ₂ group in the hydrophobic group of the emulsifier compound, it has degradability in water or soil even if it is released into the environment. PFOA derivatives are not generated as a product.
(2) Even if it has a CH ₂ group in the hydrophobic group, it is not chain-transferred during the polymerization reaction, and a high molecular weight fluorine-containing polymer equivalent to the case of using the PFOA emulsifier can be obtained. Having a CH ₂ group in the molecule indicates that it has excellent degradability in the environment. Moreover, there is no inferiority in the vulcanization physical property of the polymer obtained.
(3) The fluorine-containing polymer latex obtained by emulsion polymerization shows the same emulsion stability as the fluorine-containing polymer latex using PFOA emulsifier, but it is thought to have no affinity for polymers as high as PFOA. The amount of the remaining emulsifier in the polymer obtained by coagulating and washing the latex is much smaller than that of PFOA.
(4) If the amount of residual emulsifier is large, there is a risk that the vulcanization rate will be delayed and the crosslink density will be reduced. If the crosslink density is low, it will lead to a decrease in breaking strength and elongation and a deterioration in compression set. However, when the amount of residual emulsifier is small, such concerns are eliminated. In addition, the risk of release to the environment can be reduced by reducing the residual amount of the emulsifier in the final product.
(5) Since it is used as an emulsifier for emulsion polymerization in the same way as PFOA emulsifier, there is no need to change existing production equipment and processes.
(6) In the above general formula, M ¹ and M ² may be methyl groups, but monoesters are difficult to isolate, and diesters are not preferable because they lack water solubility.
(7) When the value of m is larger than this, the chain becomes too long, and when used in the emulsion polymerization reaction, the emulsifying ability of the fluorine-based monomer is lowered.

The perfluoroalkylalkylphosphonate used as an emulsifier for emulsion polymerization of a fluorine-containing monomer in the method of the present invention is a perfluoroalkylalkylphosphonic acid described in Patent Document 4.
C ₂ F _{2n + 1} C _m H _2m P (O) (OH) ₂
And an alkali metal hydroxide or ammonia water. Alkali metal hydroxide or ammonia forms a mono-salt when used in an equimolar amount with respect to perfluoroalkylalkylphosphonic acid, and forms a di-salt when used in a double molar amount. In general, when used in the required theoretical number of moles or more, and when used in an equimolar amount or more and less than twice the molar amount, a mixture of a mono salt and a di salt is formed.

Examples of the mono- and di-salts of perfluoroalkylalkylphosphonic acid include the following compounds.
C ₂ F ₅ CH ₂ P (O) (ONH ₄ ) (OH) C ₂ F ₅ CH ₂ P (O) (ONH ₄ ) (ONH ₄ )
C ₃ F ₇ CH ₂ P (O) (ONH ₄ ) (OH) C ₃ F ₇ CH ₂ P (O) (ONH ₄ ) (ONH ₄ )
C ₄ F ₉ CH ₂ P (O) (ONH ₄ ) (OH) C ₄ F ₉ CH ₂ P (O) (ONH ₄ ) (ONH ₄ )
C ₅ F ₁₁ CH ₂ P (O) (ONH ₄ ) (OH) C ₅ F ₁₁ CH ₂ P (O) (ONH ₄ ) (ONH ₄ )
C ₆ F ₁₃ CH ₂ P (O) (ONH ₄ ) (OH) C ₆ F ₁₃ CH ₂ P (O) (ONH ₄ ) (ONH ₄ )
C ₂ F ₅ C ₂ H ₄ P (O) (ONH ₄ ) (OH) C ₂ F ₅ C ₂ H ₄ P (O) (ONH ₄ ) (ONH ₄ )
C ₃ F ₇ C ₂ H ₄ P (O) (ONH ₄ ) (OH) C ₃ F ₇ C ₂ H ₄ P (O) (ONH ₄ ) (ONH ₄ )
C ₄ F ₉ C ₂ H ₄ P (O) (ONH ₄ ) (OH) C ₄ F ₉ C ₂ H ₄ P (O) (ONH ₄ ) (ONH ₄ )
C ₅ F ₁₁ C ₂ H ₄ P (O) (ONH ₄ ) (OH) C ₅ F ₁₁ C ₂ H ₄ P (O) (ONH ₄ ) (ONH ₄ )
C ₆ F ₁₃ C ₂ H ₄ P (O) (ONH ₄ ) (OH) C ₆ F ₁₃ C ₂ H ₄ P (O) (ONH ₄ ) (ONH ₄ )
C ₂ F ₅ C ₃ H ₆ P (O) (ONH ₄ ) (OH) C ₂ F ₅ C ₃ H ₆ P (O) (ONH ₄ ) (ONH ₄ )
C ₃ F ₇ C ₃ H ₆ P (O) (ONH ₄ ) (OH) C ₃ F ₇ C ₃ H ₆ P (O) (ONH ₄ ) (ONH ₄ )
C ₄ F ₉ C ₃ H ₆ P (O) (ONH ₄ ) (OH) C ₄ F ₉ C ₃ H ₆ P (O) (ONH ₄ ) (ONH ₄ )
C ₅ F ₁₁ C ₃ H ₆ P (O) (ONH ₄ ) (OH) C ₅ F ₁₁ C ₃ H ₆ P (O) (ONH ₄ ) (ONH ₄ )
C ₆ F ₁₃ C ₃ H ₆ P (O) (ONH ₄ ) (OH) C ₆ F ₁₃ C ₃ H ₆ P (O) (ONH ₄ ) (ONH ₄ )

C ₂ F ₅ CH ₂ P (O) (ONa) (OH) C ₂ F ₅ CH ₂ P (O) (ONa) (ONa)
C ₃ F ₇ CH ₂ P (O) (ONa) (OH) C ₃ F ₇ CH ₂ P (O) (ONa) (ONa)
C ₄ F ₉ CH ₂ P (O) (ONa) (OH) C ₄ F ₉ CH ₂ P (O) (ONa) (ONa)
C ₅ F ₁₁ CH ₂ P (O) (ONa) (OH) C ₅ F ₁₁ CH ₂ P (O) (ONa) (ONa)
C ₆ F ₁₃ CH ₂ P (O) (ONa) (OH) C ₆ F ₁₃ CH ₂ P (O) (ONa) (ONa)
C ₂ F ₅ C ₂ H ₄ P (O) (ONa) (OH) C ₂ F ₅ C ₂ H ₄ P (O) (ONa) (ONa)
C ₃ F ₇ C ₂ H ₄ P (O) (ONa) (OH) C ₃ F ₇ C ₂ H ₄ P (O) (ONa) (ONa)
C ₄ F ₉ C ₂ H ₄ P (O) (ONa) (OH) C ₄ F ₉ C ₂ H ₄ P (O) (ONa) (ONa)
C ₅ F ₁₁ C ₂ H ₄ P (O) (ONa) (OH) C ₅ F ₁₁ C ₂ H ₄ P (O) (ONa) (ONa)
C ₆ F ₁₃ C ₂ H ₄ P (O) (ONa) (OH) C ₆ F ₁₃ C ₂ H ₄ P (O) (ONa) (ONa)
C ₂ F ₅ C ₃ H ₆ P (O) (ONa) (OH) C ₂ F ₅ C ₃ H ₆ P (O) (ONa) (ONa)
C ₃ F ₇ C ₃ H ₆ P (O) (ONa) (OH) C ₃ F ₇ C ₃ H ₆ P (O) (ONa) (ONa)
C ₄ F ₉ C ₃ H ₆ P (O) (ONa) (OH) C ₄ F ₉ C ₃ H ₆ P (O) (ONa) (ONa)
C ₅ F ₁₁ C ₃ H ₆ P (O) (ONa) (OH) C ₅ F ₁₁ C ₃ H ₆ P (O) (ONa) (ONa)
C ₆ F ₁₃ C ₃ H ₆ P (O) (ONa) (OH) C ₆ F ₁₃ C ₃ H ₆ P (O) (ONa) (ONa)

  Since these perfluoroalkylalkylphosphonates have a linear fluoroalkyl group, they have better solubility in water than fluoropolyether type emulsifier compounds having the same emulsifying ability, while they were produced. Since the adhesion to fluoropolymers is lower than that of PFOA, the fluoropolymer latex obtained by coagulation of the fluoropolymer latex obtained by emulsion polymerization by various methods such as salting out, acid precipitation, mechanical stirring, etc. The amount of residual emulsifier in the polymer can be significantly reduced.

The emulsion polymerization reaction of the fluorine-containing monomer using this emulsifier is performed in the same manner as in the case of using the PFOA emulsifier. The emulsion polymerization reaction is carried out using a water-soluble inorganic peroxide such as ammonium persulfate or a redox system of it and a reducing agent as a catalyst. In this case, in order to adjust the pH in the polymerization system, phosphate (Na ₂ HPO ₄ , NaH ₂ PO ₄ , KH ₂ PO _4, etc.) or borate (Na ₂ B ₂ O _7, etc.) buffering electrolyte substance, NaOH or the like may be added. The emulsion polymerization reaction is carried out under pressure conditions at about 30 to 120 ° C. for about 1 to 48 hours using about 0.001 to 10% by weight, preferably about 0.01 to 5% by weight, of emulsifier with respect to water.

As the fluorine-containing monomer to be emulsion-polymerized, vinylidene fluoride [VdF], hexafluoropropylene [HFP], tetrafluoroethylene [TFE], pentafluoropropylene [PFP], monochlorotrifluoroethylene [CTFE], C _{1 to} C Perfluoro (alkyl vinyl ether) having ₃ alkyl groups (FAVE), perfluoro (alkoxyalkyl vinyl ether) (FOAVE) etc., at least one kind, generally carried out as a copolymerization reaction of two or three kinds, one kind When only is used, it is also carried out as a copolymerization reaction with an α-olefin such as ethylene and propylene, in addition to the homopolymerization reaction thereof. The copolymerization reaction is preferably carried out as a addition method from the viewpoint of the uniformity of the composition of the resulting fluoropolymer, particularly the fluorocopolymer elastomer.

In the copolymerization reaction, as chain transfer agents, esters such as ethyl malonate and ethyl acetate, alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone, hydrocarbons such as hexane and octane , Various halogenated hydrocarbons such as chloroform, carbon tetrachloride and dichloroethane are used. Further, iodine-containing compounds such as ICF ₂ CF ₂ I and ICF ₂ CF ₂ CF ₂ CF ₂ I, and iodine-containing bromine compounds such as ICF ₂ CF ₂ Br and ICF ₂ CF ₂ CF ₂ CF ₂ Br are used as chain transfer agents. These compounds can also play a role in forming a crosslinking site in peroxide crosslinking.

Examples of bromine-containing monomer compounds used to form a crosslinking site include vinyl bromide, vinyl iodide, 1-bromo-2,2-difluoroethylene, 1-iodo-2,2-difluoroethylene, perfluoro Allyl bromide, perfluoroallyl iodide, 4-bromo-1,1,2-trifluorobutene, 4-iodo-1,1,2-trifluorobutene, 4-bromo-3,3,4,4-tetra Brominated vinyl compounds or brominated olefins such as fluorobutene, bromotrifluoroethylene, and iodotrifluoroethylene can be used.
CR ₁ R ₂ = CR ₃ X or CR ₁ R ₂ = CR ₃ (R ₄ −X)
R ₁ , R ₂ , R ₃ : the same or different groups, H, F, Cl, C 1-10 alkyl
Group, fluoroalkyl group, and these groups contain an ether bond
May be
R _{4 is} an alkyl group having 1 to 10 carbon atoms or a fluoroalkyl group, and these groups
May contain ether linkages
X: Br, I
It may be a brominated or iodinated vinyl compound or olefin compound.

Preferably, a bromine group-containing vinyl ether represented by the following general formula is used.
BrRf-O-CF = CF ₂
BrRf: bromine group-containing perfluoroalkyl group Examples of such bromine group-containing vinyl ethers are CF ₂ BrCF ₂ OCF = CF ₂ , CF ₂ Br (CF ₂ ) ₂ OCF = CF ₂ , CF ₂ Br (CF ₂ ) ₃ OCF = _{CF 2, CF 3 CFBr (CF} 2) 2 OCF = CF 2, CF 2 Br (CF 2) 4 OCF = CF 2 or the like is used.

Besides these, bromine group-containing vinyl ethers represented by the general formula ROCF = CFBr or ROCBr = CF ₂ (R: lower alkyl group or fluoroalkyl group) can also be used.

  Examples of the iodine-containing monomer compound include iodotrifluoroethylene, 1,1-difluoro-2-iodoethylene, perfluoro (2-iodoethyl vinyl ether), vinyl iodide and the like.

  These bromine-containing or iodine-containing monomer compounds are used in a proportion of about 0.001 to 5 mol%, preferably about 0.01 to 1 mol%, based on the total amount of the fluorine-containing monomer. If the ratio is less than this, the compression set characteristics of the resulting vulcanizate are deteriorated. On the other hand, if the ratio is more than this, the elongation of the vulcanizate decreases.

  Coagulation of the obtained fluoropolymer latex is preferably performed by salting out, for example, an aqueous calcium chloride solution having a concentration of about 0.1 to 5% by weight, preferably about 0.3 to 3% by weight. Each process of filtration, water washing and drying is applied to the coagulated fluorine-containing polymer.

Examples of the polymer of the fluorinated monomer include the following, and a resinous or elastomeric fluorinated polymer can be formed depending on the copolymer composition thereof.
VdF homopolymer
TFE homopolymer
VdF-TFE copolymer
VdF-HFP copolymer
VdF-TFE-FMVE terpolymer
VdF-TFE-HFP terpolymer
VdF-TFE-CTFE terpolymer
VdF-CTFE copolymer
VdF-TFE-P terpolymer
TFE-P copolymer
TFE-E copolymer
TFE-CTFE copolymer
TFE-HFP copolymer
TFE-FMVE copolymer
TFE-FPVE copolymer
TFE-FMVE-FPVE terpolymer
TFE-FEVE-FPVE terpolymer
VdF-TFE-FMVE terpolymer, preferably VdF-HFP copolymer, VdF-TFE-FMVE terpolymer, VdF-TFE-HFP terpolymer or TFE-FMVE copolymer is used.
Note) E: Ethylene
P: Propylene
FMVE: Perfluoro (methyl vinyl ether)
FEVE: Perfluoro (ethyl vinyl ether)
FPVE: Perfluoro (propyl vinyl ether)

  Vulcanization of these fluorine-containing polymers is carried out by organic peroxide when it has a bromine group or iodine group, and polyol vulcanization or the like otherwise.

  Examples of the organic peroxide used in the peroxide vulcanization method include 2,5-dimethyl-2,5-bis (tertiary butylperoxy) hexane, 2,5-dimethyl-2,5-bis (tertiary (Butyl peaoxy) hexyne-3, benzoyl peroxide, bis (2,4-dichlorobenzoyl) peroxide, dicumyl peroxide, di-tert-butyl peroxide, tert-butyl cumyl peroxide, tert-butyl peroxybenzene, 1 , 1-Bis (tert-butylperoxy) -3,5,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, α, α'-bis (tert-butylperoxy)- p-diisopropylbenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, tert-butylperoxyisopropyl carbonate and the like are used.

  In the peroxide vulcanization method in which these organic peroxides are used, polyfunctional unsaturated compounds such as tri (meth) allyl isocyanurate, tri (meth) allyl cyanurate, triallyl trimellitate are usually used as co-crosslinking agents. N, N′-m-phenylenebismaleimide, diallyl phthalate, tris (diallylamine) -s-triazine, triallyl phosphite, 1,2-polybutadiene, ethylene glycol diacrylate, diethylene glycol diacrylate, and the like are used in combination.

  Each of the above components to be blended in the peroxide vulcanization system generally comprises about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight of organic peroxide per 100 parts by weight of the fluoropolymer. Are used in an amount of about 0.1 to 10 parts by weight, preferably about 0.5 to 5 parts by weight.

  In the case of polyol vulcanization, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxyphenyl) perfluoropropane (bisphenol AF) as polyol-based crosslinking agents , Hydroquinone, catechol, resorcin, 4,4'-dihydroxydiphenyl, 4-4'-dihydroxydiphenylmethane, 4,4'-dihydroxydiphenylsulfone, 2,2-bis (4-hydroxyphenyl) butane, etc. Compounds or their alkali metal salts or alkaline earth metal salts are used, and these polyol crosslinking agents are used at a ratio of about 0.5 to 10 parts by weight, preferably about 1 to 5 parts by weight, per 100 parts by weight of the fluorine-containing elastomer. It is done.

  Further, as a vulcanization accelerator for the polyol crosslinking reaction, a quaternary onium salt such as a quaternary ammonium salt or a quaternary phosphonium salt is about 0.1 to 30 parts by weight, preferably about 0.2 to 20 parts by weight per 100 parts by weight of the fluorine-containing elastomer. It is used in the proportion of parts.

  Furthermore, as a polyol-based cross-linking agent or a quaternary phosphonium salt, or both, a compound in which a bisphenol compound is reacted with a 2 molar amount of a quaternary phosphonium halide, that is, a bisphenol compound having a quaternary phosphonium base at both ends. It can also be used alone or in combination with other vulcanizing agents.

  Each of the above vulcanized components may be blended and kneaded with the fluorine-containing elastomer as they are, or diluted with carbon black, silica, clay, talc, diatomaceous earth, barium sulfate, etc. Also used as a masterbatch dispersion. In the composition, in addition to the above components, conventionally known fillers or reinforcing agents (carbon black, silica, graphite, clay, talc, diatomaceous earth, barium sulfate, titanium oxide, wollastonite, etc.), plastic Agents, lubricants, processing aids, pigments and the like can be appropriately blended.

  Vulcanization is carried out by mixing the above components by a commonly used mixing method such as roll mixing, kneader mixing, Banbury mixing, or solution mixing, and then heating. Vulcanization is generally performed by primary vulcanization performed at about 100 to 250 ° C. for about 1 to 120 minutes and secondary vulcanization performed at about 150 to 300 ° C. for about 0 to 30 hours, but injection molding is also possible. It is.

  Next, the present invention will be described with reference to examples.

Reference Example 1 [Synthesis of 2- (perfluorohexyl) ethylphosphonic acid monoammonium salt]
Into a reaction vessel having a capacity of 200 ml equipped with a stirrer and a dropping device, 50 g of water heated to 40 ° C. was charged while being kept warm, and 2- (perfluorohexyl) ethylphosphonic acid (Unimatec product CHEMINOX FHP-2- After 5 g (11.7 mmol) of OH) was added, 15.7 g (NH ₃ min: 12.9 mmol) of an aqueous ammonia solution having a concentration of 1.4 wt% was added, and stirring was continued for 1 hour to carry out a neutralization reaction. This gave 70.6 g of an aqueous solution of ammonium 2- (perfluorohexyl) ethylphosphonate having a pH of 7.6. This aqueous solution was dried in a vacuum dryer (6.666 × 10 ² Pa) at 50 ° C. for 12 hours to obtain 5.1 g of 2- (perfluorohexyl) ethylphosphonic acid monoammonium salt (yield 98.1%).

Reference Example 2 [Synthesis of 2- (perfluorohexyl) ethylphosphonic acid diammonium salt]
Into a 300 ml reaction vessel equipped with a stirrer and a dropping device, 50 g of water heated to 40 ° C. was charged while being kept warm, and 2- (perfluorohexyl) ethylphosphonic acid (Unimatec product CHEMINOX FHP-2- After 5 g (11.7 mmol) of OH) was added, 31.4 g (NH ₃ min: 25.8 mmol) of an aqueous ammonia solution having a concentration of 1.4 wt% was added, and stirring was continued for 2 hours to carry out a neutralization reaction. As a result, 86.1 g of an aqueous solution of ammonium 2- (perfluorohexyl) ethylphosphonate having a pH of 11.4 was obtained. This aqueous solution was dried in a vacuum dryer (6.666 × 10 ² Pa) at 50 ° C. for 12 hours to obtain 5.2 g (yield 96.3%) of 2- (perfluorohexyl) ethylphosphonic acid diammonium salt.

Example 1
In a 10L stainless steel pressure vessel with a stirrer,
20 g of emulsifier compound (monoammonium salt) obtained in Reference Example 1
Buffer (Na ₂ HPO ₄・ 12H ₂ O) 20g
Chain transfer agent (ethyl malonate) 2.6g
Ion exchange water 5100g
Was replaced with nitrogen to remove oxygen in the reaction vessel. Thereafter, 120 g of HFP and 351 g of a mixed gas of VdF / TFE (molar ratio 57.8 / 42.2) were introduced, and the temperature in the reactor was raised to 80 ° C. The pressure inside the reactor when reaching 80 ° C. was 2.14 MPa · G.

  After confirming the stability of the temperature in the reactor, 100 g of an aqueous solution in which 0.48 g of ammonium persulfate was dissolved was introduced into the reactor as a polymerization initiator to initiate the polymerization reaction. When the polymerization reaction progressed and the pressure in the reactor reached 1.75 MPa · G, a VdF / TFE / HFP (molar ratio 54.4 / 39.7 / 5.9) mixed gas was introduced and the pressure was increased to 1.85 MPa · G. During the polymerization reaction, the reaction pressure was kept in the range of 1.75 to 1.85 MPa · G by introducing a mixed gas having this composition.

  When the total amount of the mixed gas added became 1680 g, the introduction of the mixed gas was stopped, and when the internal pressure of the reactor reached 1.75 MP · G, the reactor was cooled to stop the polymerization reaction. It took 255 minutes from the introduction of the polymerization initiator to the termination of the polymerization reaction to obtain 6710 g of a fluoropolymer latex.

  The obtained fluoropolymer latex is put into the same amount of 1% by weight calcium chloride aqueous solution, the latex is agglomerated by salting out, filtered, washed 5 times with ion exchange water 5 times and vacuum dried. As a result, 1630 g of a resinous VdF / TFE / HFP terpolymer was obtained.

The copolymer composition (measured by ¹⁹ F-NMR) of this resinous terpolymer is VdF / TFE / HFP molar ratio = 55.1 / 40.8 / 4.1, and its weight average molecular weight Mw (measured by GPC) is It was about 5.5 × 10 ⁵ .

Further, the amount of residual emulsifier in the ternary copolymer was measured as follows.
The emulsifier in the terpolymer powder was Soxhlet extracted with an ethanol / water (volume ratio 95/5) solution, and the resulting extract was subjected to LC-MS / MS measurement under the following conditions. Was 15.7 ppm.
LC-MS / MS measurement: Prominence series LC-20A manufactured by Shimadzu Corporation and Applied Biosys
Uses a system consisting of Temu Japan 4000Q TRAP Column: Mightysil RP-18 (L) GP100-20 manufactured by Kanto Chemical Uses 5μm Mobile phase: A; 5mmol / L ammonium acetate aqueous solution
B; acetonitrile
Use a two-component gradient

Furthermore, in order to evaluate the stability of the fluoropolymer latex, the amount of aggregate (PHL) in the latex after the polymerization reaction was measured. The measurement was performed by filtering about 1 kg of latex using a 300-mesh filter and measuring the filtered residue. PHL was calculated by the following formula, and a value of 0.0023 PHL was obtained.
PHL = Residual excess (g) x 100 / Round latex (g)

Comparative Example 1
In Example 1, a copolymerization reaction was carried out using the same amount of ammonium perfluorooctanoate instead of phosphonate as an emulsifier (polymerization time 228 minutes) to obtain 6740 g of a fluorine-containing polymer latex. Thereafter, 1640 g of a resinous VdF / TFE / HFP terpolymer was obtained in the same manner.

The copolymer composition of the obtained resinous terpolymer is VdF / TFE / HFP molar ratio = 55.4 / 40.6 / 4.0, weight average molecular weight Mw is about 5.4 × 10 ⁵ , residual emulsifier amount is 339 ppm, agglomeration The physical quantity was 0.0019PHL.

Comparative Example 2
In Example 1, a copolymerization reaction was carried out using the same amount of CF ₃ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH ₄ instead of phosphonate as an emulsifier (polymerization time 315 minutes), and 6700 g of content was contained. A fluoropolymer latex was obtained. Thereafter, 1580 g of a resinous VdF / TFE / HFP terpolymer was obtained in the same manner.

The copolymer composition of the obtained resinous terpolymer is VdF / TFE / HFP molar ratio = 55.0 / 41.1 / 3.9, the weight average molecular weight Mw is about 5.5 × 10 ⁵ , the residual emulsifier amount is 721 ppm, the aggregation The quantity was 0.0121PHL.

Example 2
In Example 1, instead of the emulsifier compound (monoammonium salt) obtained in Reference Example 1, the same amount (20 g) of the emulsifier compound (diammonium salt) obtained in Reference Example 2 was used for the copolymerization reaction. For 241 minutes to obtain 6690 g of a fluoropolymer latex.

  This fluoropolymer latex was salted out and agglomerated to obtain 1610 g of a resinous VdF / TFE / HFP terpolymer. The copolymer composition of this resinous terpolymer was VdF / TFE / HFP molar ratio = 55.4 / 40.4 / 4.2. Further, the residual emulsifier amount in the ternary copolymer was 12.2 ppm, and the aggregate amount was 0.0025 PHL.

Example 3
(1) To a 30L stainless steel pressure vessel equipped with a stirrer,
15.1 kg of water
60 g of emulsifier compound (monoammonium salt) obtained in Reference Example 1
Buffer (Na ₂ HPO ₄・ 12H ₂ O) 4g
Chain transfer agent (ICF ₂ CF ₂ CF ₂ CF ₂ I) 60 g
And then
TFE 315g (11.8mol%)
VdF 550g (32.1 mol%)
HFP 2250g (56.1mol%)
And the temperature in the reaction vessel was raised to 70 ° C. The pressure inside the reactor when the temperature reached 70 ° C. was 3.09 MPa · G.

  Next, 500 g of an aqueous solution in which 1.5 g of ammonium persulfate was dissolved was introduced into the reactor as a polymerization initiator to initiate the polymerization reaction. Since the polymerization reaction proceeds and the pressure in the reactor decreases, the TFE / VdF / HFP (molar ratio 21.7 / 53.0 / 25.3) gas mixture is reacted so that the pressure in the reactor is maintained at 2.9 to 3.0 MPa · G. It was added to the vessel, and when the amount of added gas reached 5600 g (after about 10 hours), the addition was stopped and aging was performed for about 30 to 50 minutes. At this time, the pressure in the reactor was 1.77 MPa · G.

  The obtained fluoropolymer latex (23.4 kg) was put into the same amount of 4 wt% calcium chloride aqueous solution and treated in the same manner as in Example 1 to give an elastomeric VdF / TFE / HFP terpolymer 7.31. kg was obtained.

The copolymer composition of the resulting elastomeric terpolymer is elastomeric VdF / TFE / HFP molar ratio = 67.3 / 15.8 / 16.9, Mooney viscosity ML _{1 + 5} (121 ° C.) is 35 pts, the amount of residual emulsifier Was 22.2 ppm, and the aggregate amount was 0.0022 PHL.

(2) 100 parts by weight of the terpolymer obtained in (1) above
MT carbon black 20 〃
ZnO 5 〃
Triallyl isocyanurate 5 〃
(Nippon Kasei product TAIC M60)
Organic peroxide (Perhexa 25B, Japanese fat product) 3.5 〃
The above components were kneaded using an 8-inch open roll, and the kneaded product was press vulcanized at 180 ° C. for 10 minutes, and then oven vulcanized (secondary vulcanization) at 230 ° C. for 22 hours.

Comparative Example 3
(1) In Example 3 (1), a copolymerization reaction was carried out using the same amount of ammonium perfluorooctanoate instead of phosphonate as an emulsifier to obtain 23.9 kg of a fluorine-containing polymer latex.

The copolymer composition of the obtained elastomeric terpolymer was VdF / TFE / HFP molar ratio = 67/16/17, Mooney viscosity ML _{1 + 5} (121 ° C.) was 34 pts, and the residual emulsifier amount was 511 ppm. The amount of aggregate was 0.0028 PHL.

  (2) Using the resulting elastomeric terpolymer, kneading, vulcanization and measurement of various properties were carried out as in Example 3 (2).

Example 4
(1) After vacuuming a 30L stainless steel pressure vessel equipped with a stirrer, 15.5kg of water
71 g of emulsifier compound (monoammonium salt) obtained in Reference Example 1
Buffer (Na ₂ HPO ₄・ 12H ₂ O) 51g
CF ₂ = CFOCF ₂ CF ₂ Br 27g
Chain transfer agent (ICF ₂ CF ₂ Br) 30g
And then
TFE 840g (8.4mol%)
VdF 3780g (59.1mol%)
FMVE 2800g (16.9mol%)
And the temperature in the reaction vessel was raised to 50 ° C. The pressure inside the reactor when reaching 50 ° C. was 3.92 MPa · G.

  Next, 500 g of an aqueous solution in which 10 g of ammonium persulfate was dissolved was introduced into the reactor as a polymerization initiator to initiate the polymerization reaction. As the polymerization reaction progressed, the pressure in the reactor decreased. When the pressure in the reactor reached 1.2 MPa · G (after about 12.5 hours), the reactor was cooled to stop the polymerization reaction.

  The obtained fluoropolymer latex (22.5 kg) was put into the same amount of 4 wt% calcium chloride aqueous solution and treated in the same manner as in Example 1 to obtain an elastomeric VdF / TFE / FMVE terpolymer 7.1. kg was obtained.

The copolymer composition of the obtained elastomeric terpolymer was VdF / TFE / FMVE molar ratio = 73.2 / 10.0 / 16.8, Mooney viscosity ML _{1 + 5} (121 ° C.) was 32 pts, and the residual emulsifier amount was 24.8. The ppm and aggregate amount were 0.0011 PHL.

(2) 100 parts by weight of the terpolymer obtained in (1) above
MT carbon black 30 〃
ZnO 6 〃
Triallyl isocyanurate 6.7 〃
(Nippon Kasei product TAIC M60)
Organic peroxide (Perhexa 25B, Japanese fat product) 3.5 〃
The above components were kneaded using an 8-inch open roll, and the kneaded product was press vulcanized at 180 ° C. for 10 minutes, and then oven vulcanized (secondary vulcanization) at 230 ° C. for 22 hours.

Comparative Example 4
(1) In Example 4 (1), instead of the emulsifier compound (monoammonium salt) obtained in Reference Example 1, 71 g of ammonium perfluorooctanoate was used for the copolymerization reaction for 720 minutes to obtain 22.4 kg. The fluoropolymer latex was obtained.

This fluoropolymer latex was salted out and agglomerated to obtain 7.1 kg of a VdF / TFE / FMVE terpolymer. The copolymer composition of this terpolymer was VdF / TFE / FMVE molar ratio = 73.0 / 10.1 / 16.9, and its Mooney viscosity ML _{1 + 5} (121 ° C.) was 32 pts. The residual emulsifier amount in the elastomeric terpolymer was 490 ppm, and the aggregate amount was 0.0020 PHL.

  (2) Using the resulting elastomeric terpolymer, kneading, vulcanization and measurement of various properties were carried out as in Example 4 (2).

Example 5
(1) After vacuuming a 10L stainless steel pressure vessel equipped with a stirrer, there was 5.4kg of water.
120 g of emulsifier compound (monoammonium salt) obtained in Reference Example 1
Buffer (KH ₂ PO ₄・ 12H ₂ O) 78g
Chain transfer agent (ICF ₂ CF ₂ Br) 8g
And then
TFE 130g (1.30mol%)
FMVE 130g (0.76mol%)
And the temperature in the reaction vessel was raised to 60 ° C. The pressure inside the reactor when reaching 60 ° C. was 0.84 MPa · G.

  Subsequently, 200 g of an aqueous solution in which 7 g of ammonium persulfate was dissolved was introduced into the reactor as a polymerization initiator to initiate the polymerization reaction. As the polymerization reaction proceeds and the pressure inside the reactor decreases, the TFE / FMVE (molar ratio 62.4 / 37.6) mixed gas was added to the reactor so that the pressure inside the reactor was maintained at 0.75 to 0.85 MPa · G. Then, when the amount of gas added reached 1.72 kg (after about 18.5 hours), the addition was stopped and aging was performed for about 2 hours. The pressure inside the reactor at the end of the addition was 0.75 MPa · G.

  The obtained fluoropolymer latex (7.2 kg) was put into the same amount of 4 wt% calcium chloride aqueous solution and treated in the same manner as in Example 1 to obtain 1.6 kg of an elastomeric TFE / FMVE copolymer. It was.

The copolymer composition of the obtained elastomeric copolymer is TFE / FMVE molar ratio = 68.2 / 31.8, Mooney viscosity ML _{1 + 5} (121 ° C.) is 45 pts, residual emulsifier amount is 29.8 ppm, and aggregate amount is 0.0031. It was PHL.

(2) 100 parts by weight of the copolymer obtained in (1) above
MT carbon black 15 〃
Hydrotalcite (Kyowa Chemical Product DHT-4A) 3 〃
Triallyl isocyanurate (TAIC M60) 3.5 〃
Organic peroxide (Perhexa 25B) 0.8 〃
The above components were kneaded using an 8-inch open roll, and the kneaded product was press vulcanized at 180 ° C. for 10 minutes, and then oven vulcanized (secondary vulcanization) at 230 ° C. for 22 hours.

Comparative Example 5
(1) In Example 5 (1), instead of the emulsifier compound (monoammonium salt) obtained in Reference Example 1, 120 g of ammonium perfluorooctanoate was used for the copolymerization reaction for 990 minutes, and 7.3 kg The fluoropolymer latex was obtained.

This fluoropolymer latex was salted out and agglomerated to obtain 1.6 kg of an elastomeric TFE / FMVE copolymer. The copolymer composition of this elastomeric copolymer was TFE / FMVE molar ratio = 68.0 / 32.0, and its Mooney viscosity ML _{1 + 5} (121 ° C.) was 47 pts. The residual emulsifier amount in the copolymer was 631 ppm, and the aggregate amount was 0.0033 PHL.

  (2) Using the obtained elastomeric copolymer, kneading, vulcanization and measurement of various properties were carried out as in Example 5 (2).

Example 6
(1) After vacuuming a 10L stainless steel pressure vessel equipped with a stirrer, there was 5.1 kg of water.
Emulsifier compound (monoammonium salt) obtained in Reference Example 1 8g
Buffer (NaH ₂ PO ₄・ 12H ₂ O) 6g
Chain transfer agent (isopropanol) 10.6 g
And then
VdF 180g (2.81mol%)
HFP 540g (3.6mol%)
And the temperature in the reaction vessel was raised to 80 ° C. The pressure in the reactor when reaching 80 ° C. was 2.81 MPa · G.

  Next, 200 g of an aqueous solution in which 6.5 g of ammonium persulfate was dissolved was introduced into the reactor as a polymerization initiator to initiate the polymerization reaction. Next, a VdF / HFP (molar ratio 82.4 / 17.6) mixed gas was added to adjust the pressure in the reactor to 3.2 MPa · G. Since the polymerization reaction proceeds and the pressure in the reactor decreases, the mixed gas having the above composition is added to the reactor so that the pressure in the reactor is maintained at 3.1 to 3.2 MPa · G. When the pressure reaches 2.16 kg, the addition is stopped, aging is performed when the pressure inside the reactor reaches 3.1 MPa · G, and the reactor is cooled when the pressure inside the reactor reaches 1.9 MPa · G. The reaction was stopped (reaction time about 3.5 hours).

  The obtained fluoropolymer latex (7.3 kg) was put into the same amount of 4 wt% calcium chloride aqueous solution and treated in the same manner as in Example 1 to obtain 2.2 kg of an elastomeric VdF / HFP copolymer. It was.

The copolymer composition of the obtained elastomeric copolymer was VdF / HFP molar ratio = 78.1 / 21.9, Mooney viscosity ML _{1 + 5} (121 ° C.) was 41 pts, the residual emulsifier amount was 24.8 ppm, and the aggregate amount was 0.0027. It was PHL.

(2) 100 parts by weight of the copolymer obtained in (1) above
MT carbon black 25 〃
MgO 3 〃
2,2- (4-hydroxyphenyl) hexafluoropropane 2
Benzyltriphenylphosphonium chloride 0.3 〃
The above components were kneaded using an 8-inch open roll, and the kneaded product was press vulcanized at 180 ° C. for 10 minutes, and then oven vulcanized (secondary vulcanization) at 230 ° C. for 22 hours.

Comparative Example 6
(1) In Example 6 (1), instead of the emulsifier compound (monoammonium salt) obtained in Reference Example 1, 8 g of ammonium perfluorooctanoate was used for copolymerization for 210 minutes, and 7.3 kg The fluoropolymer latex was obtained.

This fluoropolymer latex was salted out and agglomerated to obtain 2.2 kg of an elastomeric VdF / HFP copolymer. The copolymer composition of this elastomeric copolymer was VdF / HFP molar ratio = 77.9 / 22.1, and its Mooney viscosity ML _{1 + 5} (121 ° C.) was 40 pts. The residual emulsifier amount in the copolymer was 491 ppm, and the aggregate amount was 0.0030 PHL.

  (2) Using the resulting elastomeric copolymer, kneading, vulcanization and measurement of various properties were carried out as in Example 6 (2).

Various characteristics of the vulcanizates obtained in the above Examples and Comparative Examples were measured, and the following values were obtained. The compression set was measured for the P-24 O-ring according to ASTM Method B. The results obtained are shown in the following table.
table
Measurement item Real-3 ratio-3 Real-4 ratio-4 Real-5 ratio-5 Real-6 ratio-6
100% modulus (MPa) 4.2 4.2 3.7 3.8 − − − −
Elongation at break (%) 215 210 300 290 180 190 190 190
Strength at break (MPa) 18.0 17.7 19.8 19.5 19.1 18.5 12.8 12.5
Compression set
150 ° C, 70 hours (%) 8 9 17 15 − − − −
200 ° C, 70 hours (%) 22 23 27 29 − − − −
230 ° C, 70 hours (%) 41 42 60 59 − − − −

Claims (5)

General formula
C _n F _{2n + 1} C _m H _2m P (O) (OM ¹ ) (OM ² )
Wherein M ¹ is a hydrogen atom, an alkali metal or an ammonium group, M ² is an alkali metal or an ammonium salt, n is an integer of 2 to 6, and m is an integer of 1 to 3. A process for producing a fluorine-containing polymer latex, wherein a fluorine-containing monomer is emulsion-polymerized using a perfluoroalkylalkylphosphonate as an emulsifier.   A fluorine-containing polymer latex obtained by the method according to claim 1.   A fluorine-containing polymer obtained by coagulating the fluorine-containing polymer latex according to claim 2.   The fluorine-containing polymer according to claim 3, obtained by salting out the fluorine-containing polymer latex.   The fluorine-containing polymer according to claim 3 or 4, wherein the polymer molecule has a bromine-containing or iodine-containing monomer compound, or a bromine group and / or iodine group derived from an iodine-containing bromine compound as a crosslinkable group.