JP2008297529A - Production method for vinylidene fluoride-based polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for a fluorine-containing resin, allowing improvement of solubility to a solvent or a (meth)acrylic monomer. <P>SOLUTION: In this production method for the fluorine-containing resin, (a) a fluorine-containing olefin, (b) malonic acid, a malonic acid monoester, or a malonic acid diester, and (c) a water-soluble radical polymerization initiator are added into the water, and emulsification polymerization is performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a fluorine-containing resin in which a fluorine-containing olefin is subjected to emulsion polymerization with a water-soluble radical polymerization initiator in the presence of malonic acid, malonic acid monoester or malonic acid diester.

  Fluoropolymers have the advantage of being excellent in weather resistance, water and oil repellency, antifouling properties, chemical stability, non-adhesiveness, lubricity, heat resistance, flame resistance, etc. It is difficult to use in large quantities. Therefore, a fluorine-based low molecular weight compound or a fluororesin is added as an additive to a general-purpose resin such as a (meth) acrylic polymer.

  By the way, when manufacturing a fluorine-containing resin by emulsion polymerization, the method of adding and polymerizing a fluorine-containing olefin and a water-soluble polymerization initiator in water has been known for a long time. For example, Patent Document 1 describes that a vinylidene fluoride polymer is produced using a fluorosurfactant, and the vinylidene fluoride polymer obtained by the production method is a water-soluble polymerization. Since it has an ionic end group derived from an initiator, the solubility in a solvent is poor, and there is room for improvement.

  Patent Document 2 describes that when vinylidene fluoride is subjected to emulsion polymerization using a persulfate as a water-soluble polymerization initiator, methyl acetate or ethyl acetate is added as a chain transfer agent to produce polyvinylidene fluoride. Is described. By adding the chain transfer agent, it is possible to obtain a polyvinylidene fluoride with little decrease in polymerization rate and good stability, but the ionic end groups derived from the water-soluble polymerization initiator in the polymer remain. There was room for improvement in the solubility of the resulting polymer in the solvent.

  Further, in Comparative Example 4 of Patent Document 3, diethyl malonate is used as a chain transfer agent, but a combination of potassium permanganate and oxalic acid is used as an initiator, and a water-soluble radical polymerization initiator is used. Not.

JP-A-7-90153 JP 58-65711 A JP-T-2004-528451

  An object of this invention is to provide the manufacturing method of the fluorine-containing resin which the solubility with respect to a solvent improves.

  The present invention relates to a method for producing a fluorine-containing resin in which emulsion polymerization is carried out by adding (a) a fluorine-containing olefin, (b) malonic acid, a malonic acid monoester or a malonic acid diester and (c) a water-soluble radical polymerization initiator to water. About.

  Further, (d) a surfactant may be added to the water-soluble solvent.

  The fluorinated olefin (a) is preferably vinylidene fluoride or a mixture of vinylidene fluoride and other copolymerizable olefins.

  The other copolymerizable olefin is preferably at least one selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and chlorotrifluoroethylene.

  The fluorinated olefin (a) is preferably a mixture of vinylidene fluoride, chlorotrifluoroethylene and tetrafluoroethylene.

（式中、Ｒ¹およびＲ²は、同じであっても異なっていてもよく、いずれも炭素数１〜６のアルキル基、または水素原子）
であることが好ましい。 Malonic acid, malonic acid monoester or malonic acid diester (b) is represented by the formula (1):

(In the formula, R ¹ and R ² may be the same or different and both are alkyl groups having 1 to 6 carbon atoms or hydrogen atoms)
It is preferable that

  Moreover, this invention relates also to the fluorine-containing resin obtained by the said manufacturing method.

  Furthermore, this invention relates also to the aqueous dispersion composition containing the said fluorine-containing resin.

  According to the production method of the present invention, by adding malonic acid, malonic acid monoester or malonic acid diester, the ionic terminal of the polymer by the water-soluble radical polymerization initiator can be capped. Therefore, the obtained polymer can improve solvent solubility.

  The production method of the present invention is characterized in that (a) a fluorine-containing olefin, (b) malonic acid, malonic acid monoester or malonic acid diester and (c) a water-soluble radical polymerization initiator are added to water for emulsification. To do.

  Examples of the fluorinated olefin (a) include vinylidene fluoride (VdF), tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), trifluoropropylene, vinyl fluoride (VF), Examples thereof include one or a mixture of two or more of perfluoromethyl vinyl ether (PMVE) and the like, but VdF or a mixture of VdF and other copolymerizable olefins from the viewpoint of good solubility in organic solvents. It is preferable that

  The blending amount of VdF is preferably 60 to 85 mol% and more preferably 70 to 80 mol% in the fluorinated olefin (a) from the viewpoint of good solubility in an organic solvent.

  Specifically, VdF / TFE (60 to 99/1 to 40 mol%), VdF / TFE / HFP (60 to 98/1 to 39/39 to 39 mol%), VdF / TFE / CTFE (60 to 98). / 1-39 / 1-39 mol%), VdF / HFP (60-99 / 1-40 mol%), VdF / CTFE (60-99 / 1-40 mol%), etc., and particularly organic solvents From the viewpoint of solubility in VdF / TFE / CTFE is more preferable.

のものがあげられる。 By blending malonic acid, malonic acid monoester or malonic acid diester (b), the resulting polymer can cap the ionic terminal derived from the water-soluble radical polymerization initiator, and improve the solubility in the solvent. be able to. As malonic acid, malonic acid monoester or malonic acid diester (b), formula (1):

Things.

In formula, in formula, R < ¹ > and R < ² > may be same or different, and all are C1-C6 or a hydrogen atom, Preferably it is a C1-C3 alkyl group.

  Specific examples include diethyl malonate, dimethyl malonate, methyl ethyl malonate and the like, and diethyl malonate is particularly preferable from the viewpoint of cost.

  The blending amount of malonic acid, malonic acid monoester or malonic acid diester (b) is based on 100 parts by mass of the water-soluble radical polymerization initiator (c) from the viewpoint of good capping efficiency of the ionic terminal of the polymer. 10 parts by mass or more is preferable, and 10,000 parts by mass or less is preferable.

  The water-soluble radical polymerization initiator (c) is not particularly limited as long as it generates a radical that can be used for a free radical reaction in an aqueous medium at a temperature of 20 to 90 ° C. Examples of the agent include potassium persulfate, ammonium salt, and hydrogen peroxide. Specific examples include ammonium persulfate (APS), potassium persulfate (KPS), and sodium persulfate. Among these, APS and KPS are preferably used because of their good ability to generate ionic end groups. it can.

Moreover, about the said water-soluble radical polymerization initiator (c), it is also possible to employ a low-temperature decomposition type initiator system using a redox reaction by adding a reducing agent as necessary. Preferred reducing agents include sulfites such as sodium sulfite and sodium hydrogen sulfite, metabisulfites such as sodium hydrogen sulfite and potassium hydrogen sulfite, pyrosulfates, and thiosulfates. When sulfite is used, the ionic end group may be SO ₃ .

  The amount of the water-soluble radical polymerization initiator (c) is preferably 0.005% by mass or more, more preferably 0.01% by mass or more based on water, from the viewpoint of increasing the polymerization rate, and 0.02 The mass% or more is more preferable. The amount of the water-soluble radical polymerization initiator (c) is preferably 1.0% by mass or less, and preferably 0.5% by mass with respect to water, from the viewpoint that the electrolyte concentration can be lowered and the average primary particle size can be reduced. The following is more preferable, and 0.2% by mass or less is more preferable.

In the emulsion polymerization of the present invention, the polymerization may be performed in the absence of a surfactant, or the surfactant (d) may be blended in a water-soluble solvent. As the surfactant (d), the fluorine-based surfactant (a) is preferable from the viewpoint that the fluorine-containing olefin (a) can be stably emulsified. Specifically, C ₅ F ₁₁ COONH ₄ or R _f COONH ₄ typified by C ₇ F ₁₅ COONH ₄ (R _f is a C 3-20 perfluoroalkyl group) surfactant, bis (perfluoroalkanesulfonyl) imide described in JP-T-2004-533511 or Surfactants containing such salts, surfactants represented by CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ SO ₃ M (M = NH ₄ , H) described in JP-T-2004-509993, Surfactants represented by C ₃ F ₇ OCF (CF ₃ ) COONH ₄ , C ₃ F ₇ OCF (CF ₃ ) CF ₂ OCF (CF ₃ ) COONH _{4 and the} like described in JP-A 61-223007. I can get lost.

  Moreover, you may mix | blend a non-fluorine-type surfactant. Specific examples include nonionic non-fluorine surfactants, anionic non-fluorine surfactants, and amphoteric surfactants.

  Specific examples of nonionic non-fluorine surfactants include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, glycerin Examples thereof include esters and derivatives thereof. More specifically, examples of polyoxyethylene alkyl ethers include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene behenyl ether, and the like. Examples of oxyethylene alkyl phenyl ethers include polyoxyethylene nonyl phenyl ether and polyoxyethylene octyl phenyl ether. Examples of polyoxyethylene alkyl esters include polyethylene glycol monolaurate, polyethylene glycol monooleate, and monostearic acid. Polyethylene glycol and the like, and polyoxyethylene monolaurate as sorbitan alkyl esters. Examples thereof include polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan monoesters as polyoxyethylene sorbitan alkyl esters. Examples include polyoxyethylene sorbitan, polyoxyethylene sorbitan monostearate, and glyceryl esters such as glyceryl monomyristate, glyceryl monostearate, and glyceryl monooleate. Examples of these derivatives include polyoxyethylene alkylamines, polyoxyethylene alkylphenyl-formaldehyde condensates, polyoxyethylene alkyl ether phosphates, and the like. Particularly preferred are polyoxyethylene alkyl ethers and polyoxyethylene alkyl esters having an HLB value of 10-18, specifically, polyoxyethylene lauryl ether (EO: 5-20). The number of ethylene oxide units is indicated.) Polyethylene glycol monostearate (EO: 10 to 55), polyethylene glycol monooleate (EO: 6 to 10).

  Examples of the anionic non-fluorine surfactant include esters of higher alcohol sulfates such as sodium alkyl sulfonate, sodium alkyl benzene sulfonate, sodium dialkyl ester succinate, alkyl diphenyl ether disulfonate sodium, and the like. It is done.

  Examples of amphoteric surfactants include lauryl betaine.

  The blending amount of the surfactant (d) is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and 0% by mass with respect to water, from the viewpoint of cost reduction in the fluorosurfactant. More preferably, it is 2% by mass or less. The blending amount of the non-fluorinated surfactant is preferably 1% by mass or less, more preferably 0.1% by mass or less, and more preferably 0.05% by mass or less based on water from the viewpoint of a decrease in polymerization rate due to chain transfer. Is more preferable.

  The polymerization pressure at the time of emulsion polymerization is preferably 0.1 MPa or more, more preferably 0.3 MPa or more, and further preferably 0.5 MPa or more in terms of gauge pressure from the viewpoint that the polymerization rate is high. In addition, the polymerization pressure at the time of emulsion polymerization is preferably 5 MPa or less, more preferably 2 MPa or less in terms of gauge pressure, and further preferably 1 MPa or less from the viewpoint that no incidental equipment is required for high pressure.

  The polymerization temperature for carrying out the emulsion polymerization is preferably 20 ° C. or higher, more preferably 30 ° C. or higher, and even more preferably 40 ° C. or higher from the viewpoint that the stability of the aqueous dispersion to be produced is good. In addition, the polymerization temperature at the time of emulsion polymerization is preferably 120 ° C. or less, more preferably 100 ° C. or less, and further preferably 90 ° C. or less, from the viewpoint that the polymerization rate is not easily stalled by chain transfer.

  When performing emulsion polymerization, a chain transfer agent, a pH adjuster, etc. may be added as optional components.

  The production method of the present invention includes, for example, charging deionized water in a pressure-resistant reaction vessel, repeating nitrogen injection and degassing, removing residual air, and then containing the fluorinated olefin (a), malonic acid, and malonic acid monoester. Alternatively, the reaction is preferably performed by adding the malonic acid diester (b), further adding the water-soluble radical polymerization initiator (c), and then continuously supplying the fluorinated olefin (a).

  Further, the present invention may be produced by a method in which the polymerization is divided into two stages, and further, a plurality of polymer particles are synthesized by the first stage polymerization, and the second stage polymerization is performed using the obtained emulsion. .

  In this case, the particle size of the polymer obtained with a small amount of emulsifier can be kept low, and as a result, a stable emulsion can be obtained. The obtained polymer particles are also preferable because they have a uniform particle size and the polymer content can be increased. In carrying out the polymerization in two stages, malonic acid, malonic acid monoester or malonic acid diester may be added during the first stage polymerization, or may be added during the two stage polymerization.

  The number average molecular weight of the obtained fluorine-containing resin is preferably 5,000 or more, more preferably 8,000 or more, and more preferably 10,000 or more from the viewpoint that the mechanical properties and weather resistance are good during coating. Is more preferable. In addition, the number average molecular weight of the obtained fluorine-containing resin is preferably 1,000,000 or less, more preferably 500,000 or less, from the viewpoint of good solvent solubility and leveling properties during coating. More preferred is 100,000 or less.

  The average primary particle diameter of the obtained fluororesin is preferably 50 nm or more, more preferably 80 nm or more, and even more preferably 100 nm or more from the viewpoint that the viscosity is low and a high-concentration aqueous dispersion can be obtained. In addition, the average primary particle size of the obtained fluororesin is preferably 3,000 nm or less, preferably 1,000 nm or less, from the viewpoint of storage stability of the aqueous dispersion and good gloss when adjusting the coating film. More preferred is 500 nm or less.

  The present invention also relates to an aqueous dispersion composition containing a fluororesin obtained by the above production method.

  The solid content concentration of the fluororesin is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass or more in the aqueous dispersion composition from the viewpoint that the amount of the obtained polymer is large. In addition, the content of the fluororesin is preferably 50% by mass or less, more preferably 40% by mass or less, in the aqueous dispersion composition, from the viewpoint of the stability of the aqueous dispersion and the small amount of deposits during polymerization. A mass% or less is more preferable.

  The vinylidene fluoride polymer of the present invention contains other additives such as a solvent, a pigment, a thickener, a dispersant, an antifoaming agent, an antifreezing agent, and a film forming aid. Can be used as a solvent paint, water-based paint, and powder paint.

  As the coating method, the same method of applying with the same brush or roller as before, spraying method such as air spray, airless spray, aerosol, dipping method, roll coating method, ink coating method etc. can be adopted, for example tile, cement, concrete Can be painted on ceramics, wood, metal, plastic, rubber, etc.

  The paint composition includes a weather-resistant paint composition, particularly a weather-resistant paint composition for construction and building materials, an interior / exterior paint composition for automobiles, an interior / exterior paint composition for electrical products, office equipment or kitchen appliances. Examples of such coating compositions and moisture-proof coating compositions for electronic parts or printed boards are particularly applicable to weathering coating compositions for building materials from the viewpoint of good weather resistance and durability.

  EXAMPLES Next, the present invention will be specifically described with reference to examples, but the present invention is not limited only to these examples.

Example 1
After charging 3000 g of deionized water and 24 g of diethyl malonate into a pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 6 L, repeating nitrogen injection and degassing to remove residual air, 74/14/12 of VdF / TFE / CTFE The mixture was pressurized to 0.80 MPa with a gauge pressure at 75 ° C. using a mixed monomer in a mol% ratio. 28.5 g of 10% by mass ammonium persulfate aqueous solution was injected, and the reaction was performed while continuously supplying the mixed monomer so that the internal pressure of the tank was 0.80 MPa as a gauge pressure. Nine hours after the start of the polymerization, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and an aqueous dispersion (solid content concentration: 20% by mass) of fluoropolymer particles was obtained.

  The aqueous dispersion was coagulated by adding a 4 mass% aqueous aluminum sulfate solution. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Example 2
A pressure resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L was charged with 250 g of deionized water and 2 g of diethyl malonate, repeatedly injected with nitrogen and degassed to remove residual air, then 74/14 The pressure was increased to 0.80 MPa at 80 ° C. with a mixed monomer at a / 12 mol% ratio. The reaction was carried out while continuously feeding the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa as a gauge pressure. Nine hours after the start of the polymerization, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and an aqueous dispersion (solid content concentration: 16% by weight) of fluoropolymer particles was obtained.

  The aqueous dispersion was cooled at −20 ° C. for 12 hours and freeze-coagulated. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Example 3
A pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L was charged with 250 g of deionized water, 2 g of diethyl malonate, and 0.5 g of 50% by mass C ₅ F ₁₁ COONH ₄ aqueous solution. Then, the pressure was increased to 0.80 MPa at 80 ° C. with a mixed monomer of 74/14/12 mol% of VdF / TFE / CTFE at a gauge pressure. The reaction was carried out while continuously feeding the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa in terms of gauge pressure. Six hours after the start of the polymerization, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and an aqueous dispersion (solid content concentration: 15% by weight) of fluoropolymer particles was obtained.

  The aqueous dispersion was cooled at −20 ° C. for 12 hours and freeze-coagulated. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Example 4
A pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L was charged with 250 g of deionized water and 1 g of diethyl malonate, repeatedly injected with nitrogen and degassed to remove residual air. The pressure was increased to 0.80 MPa at 80 ° C. with a mixed monomer at a / 12 mol% ratio. The reaction was carried out while continuously feeding the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa in terms of gauge pressure. Nine hours after the start of the polymerization, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and an aqueous dispersion (solid content concentration: 23% by weight) of fluoropolymer particles was obtained.
The aqueous dispersion was cooled at −20 ° C. for 12 hours and freeze-coagulated. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Comparative Example 1
A pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L was charged with 250 g of deionized water and 1 g of ethyl acetate, repeatedly injected with nitrogen and degassed to remove residual air, and then VdF / TFE / CTFE The pressure was increased to 0.80 MPa with a gauge pressure at 80 ° C. with a mixed monomer of 12 mol% ratio. The reaction was carried out while continuously feeding the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa in terms of gauge pressure. After 8 hours from the start of polymerization, the inside of the tank was returned to room temperature and normal pressure to stop the polymerization, and an aqueous dispersion of fluoropolymer particles (solid content concentration 16% by weight) was obtained.
The aqueous dispersion was cooled at −20 ° C. for 12 hours and freeze-coagulated. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Comparative Example 2
After adding 250 g of deionized water to a pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L, repeating nitrogen injection and degassing, and removing residual air, the ratio of 74/14/12 mol% of VdF / TFE / CTFE The mixed monomer was pressurized to 0.80 MPa at 80 ° C. with a gauge pressure. The reaction was carried out while continuously feeding the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa in terms of gauge pressure. Three hours after the start of the polymerization, the inside of the tank was returned to normal temperature and normal pressure to stop the polymerization, and an aqueous dispersion (solid content concentration: 24% by weight) of fluoropolymer particles was obtained.

  The aqueous dispersion was cooled at −20 ° C. for 12 hours and freeze-coagulated. The obtained coagulated product was washed with water and dried to obtain a resinous polymer.

Comparative Example 3
A pressure-resistant reaction vessel equipped with a stirrer with an internal volume of 0.5 L was charged with 250 g of deionized water and 1 g of isopropyl alcohol (hereinafter also referred to as IPA), repeatedly injected with nitrogen and degassed to remove residual air, and then VdF / TFE. The pressure was increased to 0.80 MPa at 80 ° C. with a mixed monomer of 74/14/12 mol% of / CTFE. The reaction was carried out while continuously supplying the mixed monomer so that 2.4 g of a 10% by mass ammonium persulfate aqueous solution was injected and the pressure inside the tank was 0.80 MPa in gauge pressure, but the reaction did not proceed and a polymer was obtained. I couldn't.

Comparative Example 4
Polymerization was carried out in the same manner as in Comparative Example 3 except that the chain transfer agent was changed to acetylacetone, but the reaction did not proceed and a polymer could not be obtained.

  The polymerization rate (Rate of polymerization) (hereinafter also referred to as Rp) of the obtained aqueous dispersion was calculated. Moreover, the molecular weight and the average particle diameter of the obtained resinous polymer were measured by the measurement methods shown below. The measurement results are shown in Table 1.

(Rp)
The calculation formula of Rp is shown below.

(Molecular weight measurement)
The resin powder was dissolved in tetrahydrofuran (THF) to a concentration of 0.2%, and this was dissolved in polystyrene-reduced number average molecular weight and weight using a GPC measuring apparatus (trade name HLC-8020, manufactured by Tosoh Corporation). Average molecular weight was measured. If the THF was insufficiently dissolved, the residue was removed with a filter, and only the portion that passed through the column was measured.

(Solvent solubility test)
Butyl acetate was added to the resin powder to prepare a 50% by weight resin solution. The viscosity of this resin solution was measured with a B-type viscometer (manufactured by Tokyo Keiki Co., Ltd., BM-type viscometer rotor No. 4 60 rpm) at 25 ° C.

(Particle size measurement)
The average particle size of the particles in the aqueous dispersion was measured using a concentrated particle size analyzer (FPAR-1000 manufactured by Otsuka Electronics Co., Ltd.).

Claims (8)

(A) Fluorine-containing olefin, (b) Malonic acid, malonic acid monoester or malonic acid diester and (c) A water-soluble radical polymerization initiator is added to water to produce a fluorine-containing resin which undergoes emulsion polymerization. Furthermore, the manufacturing method of the fluorine-containing resin of Claim 1 which adds (d) surfactant to water. The method for producing a fluorine-containing resin according to claim 1 or 2, wherein the fluorine-containing olefin (a) is vinylidene fluoride or a mixture of vinylidene fluoride and other copolymerizable olefins. The method for producing a fluororesin according to claim 3, wherein the other copolymerizable olefin is at least one selected from the group consisting of tetrafluoroethylene, hexafluoropropylene and chlorotrifluoroethylene. The method for producing a fluorine-containing resin according to any one of claims 1 to 4, wherein the fluorine-containing olefin (a) is a mixture of vinylidene fluoride, chlorotrifluoroethylene and tetrafluoroethylene. Malonic acid, malonic acid monoester or malonic acid diester (b) is represented by the formula (1):

(In the formula, R ¹ and R ² may be the same or different and both are alkyl groups having 1 to 6 carbon atoms or hydrogen atoms)
The method for producing a fluororesin according to any one of claims 1 to 5. The fluorine-containing resin obtained by the manufacturing method in any one of Claims 1-6. An aqueous dispersion composition comprising the fluorine-containing resin according to claim 7.