WO2022124253A1

WO2022124253A1 - Copolymer, binder, molded article, and method for producing copolymer

Info

Publication number: WO2022124253A1
Application number: PCT/JP2021/044666
Authority: WO
Inventors: 遼一矢野; 貴視井口; 佳奈子新井; 和哉浅野; 寛太福島
Original assignee: ダイキン工業株式会社
Priority date: 2020-12-07
Filing date: 2021-12-06
Publication date: 2022-06-16
Also published as: TW202235462A

Abstract

Provided is a copolymer comprising vinylidene fluoride units and units of a monomer (1) represented by the general formula CX¹X²=CX³(CF₂)_nY (1) (wherein X¹, X², and X³ are each independently H, F, CH₃, CH₂F, CHF₂, or CF₃, at least one of X¹, X², and X³ being F, CH₂F, CHF₂, or CF₃, and at least one of the remainder being H or CH₃, n is an integer of 1-6, and Y is H or F), wherein the content of the monomer (1) units is 3.0-25.0 mass% with respect to all the monomer units. The copolymer has a melting point of 160°C or higher.

Description

Copolymers, Binders, Molds and Methods for Producing Copolymers

The present disclosure relates to a copolymer, a binder, a molded product, and a method for producing a copolymer.

Polyvinylidene fluoride is used in many applications such as polymer porous membranes because it has excellent chemical resistance.

Also, a copolymer of vinylidene fluoride and a comonomer is known. Patent Document 1 contains a controlled microstructure copolymer comprising a copolymer having 1 to 99% by weight of 2,3,3,3-tetrafluoropropene monomer unit and 1 to 99% by weight of vinylidene fluoride monomer unit. In the composition, the copolymer has a ratio of 2,3,3,3-tetrafluoropropene to vinylidene fluoride in the initial preparation of 0.1 to 0.9 times the constant state monomer ratio, or 1. A composition with a controlled microstructure formed by a semi-batch process, which is 1 to 10 times larger, is described.

Japanese Patent Publication No. 2014-508209

In the present disclosure, it is possible to obtain an electrode mixture having both bending resistance and flexibility, excellent heat resistance, and a viscosity that does not easily increase, and an electrode material layer having excellent electrolytic solution swelling resistance. It is an object of the present invention to provide a copolymer capable of being produced.

According to the present disclosure, vinylidene fluoride units, and
General formula (1): CX ¹ X ² = CX ³ (CF ₂ ) _n Y
(In the general formula (1), X ¹ , X ² and X ³ are independently H, F, CH ₃ , CH ₂ F, CHF ₂ or CF ₃ , but X ¹ , X ² and X ³ Of these, at least one is F, CH ₂ F, CHF ₂ or CF ₃ , at least one is H or CH ₃ , n is an integer of 1-6, and Y is H or F. ), The copolymer containing the monomer (1) unit, and the content of the monomer (1) unit is 3.0 to 25.0 mass with respect to all the monomer units. %, A copolymer having a melting point of 160 ° C. or higher is provided.

The copolymer of the present disclosure preferably has a weight average molecular weight of 2000000 or less.
In the general formula (1), n is preferably 1.
In the general formula (1), it is preferable that X ¹ and X ² are independently H or F.
The monomer (1) is 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene (Z-form) and 1,3,3,3-tetrafluoropropene (E-form). ) Is preferably at least one selected from the group consisting of.

Further, according to the present disclosure, a binder containing the above-mentioned copolymer is provided.

Further, according to the present disclosure, there is provided a molded product containing the above-mentioned copolymer, wherein the molded product is a film, a sheet, a tube or a melt-spun product.

Also, according to the present disclosure, vinylidene fluoride, and
General formula (1): CX ¹ X ² = CX ³ (CF ₂ ) _n Y
(In the general formula (1), X ¹ , X ² and X ³ are independently H, F, CH ₃ , CH ₂ F, CHF ₂ or CF ₃ , but X ¹ , X ² and X ³ Of these, at least one is F, CH ₂ F, CHF ₂ or CF ₃ , at least one is H or CH ₃ , n is an integer of 1-6, and Y is H or F. ) Is polymerized in a reactor to produce a copolymer containing a vinylidene fluoride unit and a monomer (1) unit, wherein the copolymer is produced. The content of the unit of the compounded monomer (1) is 3.0 to 25.0% by mass with respect to the total number of monomer units, and the monomer to be subjected to the polymerization before or at the start of the polymerization ( Provided is a production method in which 90% by weight or more of the monomer (1) is added to a reactor with respect to the total amount of 1) and polymerized at a polymerization temperature of 0 to 55 ° C.

In the production method of the present disclosure, the polymerization temperature is preferably 30 ° C. or higher.
In the production method of the present disclosure, the maximum pressure reached during polymerization is preferably 4.38 MPa or more.
In the production method of the present disclosure, suspension polymerization is preferably carried out in the presence of a peroxide polymerization initiator.
In the production method of the present disclosure, it is preferable to polymerize in the presence of a chain transfer agent.
In the production method of the present disclosure, it is preferable to add 90% by weight or more of vinylidene fluoride to the reactor with respect to the total amount of vinylidene fluoride to be subjected to the polymerization before or at the start of the polymerization.

According to the present disclosure, an electrode mixture having both bending resistance and flexibility, excellent heat resistance, and a viscosity that does not easily increase can be obtained, and an electrode material layer having excellent electrolytic solution swelling resistance can be obtained. It is possible to provide a copolymer that can be used.

Hereinafter, specific embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

The copolymers of the present disclosure contain vinylidene fluoride (VdF) units and monomer (1) units, and the content of the monomer (1) units is higher than that of all monomer units. It is 3.0 to 25.0% by mass. Further, the copolymer of the present disclosure has such a monomer composition and at the same time has a melting point of 160 ° C. or higher.

The monomer (1) unit is a monomer unit based on the monomer (1) represented by the general formula (1).
General formula (1): CX ¹ X ² = CX ³ (CF ₂ ) _n Y
(In general formula (1), X ¹ , X ² and X ³ are independently H, F, CH ₃ , CH ₂ F, CHF ₂ or CF ₃ , but X ¹ , X ² and X ³ Of these, at least one is F, CH ₂ F, CHF ₂ or CF ₃ , at least one is H or CH ₃ , n is an integer of 1-6, and Y is H or F. )

As X ¹ and X ² , it is preferable that they are H or F independently. If X ¹ and X ² are H or F, then X ³ may be H, F, CH ₃ , CH ₂ F, CHF ₂ or CF ₃ . Further, as X ¹ , X ² and X ³ , H or F is preferable independently, and in this case, at least one of X ¹ , X ² and X ³ is F, and at least one is H. be. It is more preferable that both X ¹ and X ² are H.

N is an integer of 1 to 6, preferably an integer of 1 to 4, more preferably an integer of 1 to 3, still more preferably 1 or 2, and particularly preferably 1.

F is preferable as Y.

As the monomer (1), the monomer represented by the general formula (1-1) is preferable.
General formula (1-1): CHX ² = CX ³ (CF ₂ ) _n Y
(In the general formula (1-1), one of X ² and X ³ is H, the other is F, and n and Y are as described above.)

Examples of the monomer (1) include 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene (Z-form) and 1,3,3,3-tetrafluoropropene (E). At least one selected from the group consisting of bodies) is preferable, and 2,3,3,3-tetrafluoropropene is more preferable.

The content of the monomer (1) unit of the copolymer is 3.0 to 25.0% by mass with respect to all the monomer units constituting the copolymer. By adjusting the content of the monomer (1) unit of the copolymer within this range, a copolymer having both bending resistance and flexibility and excellent heat resistance can be obtained. An electrode mixture whose viscosity does not easily increase can be obtained, and an electrode material layer having excellent electrolytic solution swelling resistance can be obtained. The content of the monomer (1) unit of the copolymer is preferably 4.0% by mass or more, more preferably 5.0% by mass or more, and preferably 24.0% by mass or less. More preferably, it is 23.0% by mass or less.

The content of the VdF unit of the copolymer is preferably 75.0 to 97.0% by mass with respect to all the monomer units constituting the copolymer. The content of the copolymer in VdF units is more preferably 76.0% by mass or more, further preferably 77.0% by mass or more, still more preferably 96.0% by mass or less, still more preferably. It is 95.0% by mass or less.

The copolymer may further contain a monomer unit copolymerizable with VdF and the monomer (1) other than the VdF unit and the monomer (1) unit. Examples of the monomer copolymerizable with VdF and the monomer (1) include a fluorinated monomer (however, excluding VdF and the monomer (1)), a non-fluorinated monomer, and the like. Fluorinated monomers are preferred. Examples of the fluorinated monomer include tetrafluoroethylene, vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, fluoroalkyl vinyl ether, hexafluoropropylene, (perfluoroalkyl) ethylene and the like. Examples of the non-fluorinated monomer include ethylene and propylene. The content of the monomer unit copolymerizable with VdF and the monomer (1) is preferably 0 to 5.0% by mass, more preferably 0 to 3.0% by mass, and even more preferably. It is 0 to 1.0% by mass. It is also preferable that the copolymer consists of only VdF units and monomer (1) units.

The content of the monomer unit of the copolymer can be measured by ¹⁹ F-NMR measurement.

The melting point of the copolymer is 160 ° C or higher. By adjusting the melting point of the copolymer within this range, a copolymer having both bending resistance and flexibility and excellent heat resistance can be obtained, and an electrode mixture whose viscosity does not easily increase can be obtained. It is possible to obtain an electrode material layer that is obtained and has excellent electrolytic solution swelling resistance. The melting point of the copolymer is preferably 161 ° C. or higher, more preferably 162 ° C. or higher, still more preferably 163 ° C. or higher, and the upper limit is not particularly limited, but may be 175 ° C. or lower, 170 ° C. or higher. It may be as follows.

The melting point (secondary melting point) of the copolymer is raised from 30 ° C. to 220 ° C. at a rate of 10 ° C./min and then lowered to 30 ° C. at 10 ° C./min using a differential scanning calorimetry (DSC) device. It can be obtained as the temperature with respect to the maximum value in the heat of fusion curve when the temperature is raised to 220 ° C. again at a rate of 10 ° C./min.

The solution viscosity of the copolymer is preferably 2000 mPa · s or less. By adjusting the solution viscosity of the copolymer within this range, both bending resistance and flexibility can be achieved at a higher level, and heat resistance is further improved. The solution viscosity of the copolymer is preferably 10 mPa · s or more, more preferably 50 mPa · s or more, further preferably 100 mPa · s or more, particularly preferably 150 mPa · s or more, and more preferably. It is 1800 mPa · s or less, and more preferably 1500 mPa · s or less.

The solution viscosity of the copolymer is the viscosity of the N-methyl-2-pyrrolidone (NMP) solution containing 5% by mass of the copolymer. The viscosity of the NMP solution can be measured at 25 ° C. using a B-type viscometer.

The weight average molecular weight (in terms of polystyrene) of the copolymer is preferably 50,000 to 3,000,000, more preferably 80,000 or more, further preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably 2400000 or less. It is more preferably 2000000 or less, and particularly preferably 1600000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent. By adjusting the weight average molecular weight of the copolymer within this range, both bending resistance and flexibility can be achieved at a higher level, and heat resistance is further improved.

The number average molecular weight (in terms of polystyrene) of the copolymer is preferably 20000 to 15000000, more preferably 40,000 or more, further preferably 70,000 or more, particularly preferably 140000 or more, and more preferably 140000 or less. It is more preferably 120000 or less, and particularly preferably 110000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

The storage elastic modulus of the copolymer at 25 ° C. is preferably 50 MPa or more, more preferably 100 MPa or more, still more preferably 100 MPa or more, because if the elastic modulus is too low, the resin after molding may be easily deformed. If it is 200 MPa or more and the elastic modulus is too high, the bending resistance of the resin after molding may be inferior. Therefore, it is preferably 2000 MPa or less, more preferably 1500 MPa or less, and further preferably 1200 MPa or less.

The copolymer of the present disclosure has a low rate of change between the storage elastic modulus at 25 ° C. and the storage elastic modulus at 120 ° C., and is excellent in heat resistance because it can maintain rigidity even in a high temperature atmosphere. The copolymers of the present disclosure can exhibit a rate of change in storage modulus of 800% or less.

The storage elastic modulus of a sample having a length of 30 mm, a width of 5 mm, and a thickness of 50 to 300 μm was measured by a dynamic viscoelastic device DVA220 manufactured by IT Measurement Control Co., Ltd. in a tensile mode, a grip width of 20 mm, and a measurement temperature of -30. It is a measured value at 25 ° C. or 120 ° C. when measured under the conditions of ° C. to 160 ° C., a heating rate of 2 ° C./min, and a frequency of 10 Hz.

The copolymer of the present disclosure is, for example, when polymerizing VdF and the monomer (1) in a reactor, with respect to the total amount of the monomer (1) to be subjected to the polymerization before or at the start of the polymerization. It can be produced by a production method in which 90% by weight or more of the monomer (1) is added to a reactor and polymerized at a polymerization temperature of 0 to 55 ° C.

In the above production method, 90% by weight or more of the monomer (1) is added to the reactor with respect to the total amount of the monomer (1) to be subjected to the polymerization before or at the start of the polymerization. By adding most of the monomers (1) to be subjected to the polymerization to the reactor before the start of the polymerization or at the start of the polymerization, a copolymer having a high melting point and excellent heat resistance can be obtained. Since the polymerization reaction is usually started from the time when the polymerization initiator is added, the time when the polymerization initiator is added is usually the time when the polymerization initiator is added, and the time before the start of polymerization is the time when the polymerization initiator is added. It was a time before.

The amount of the monomer (1) added before or at the start of the polymerization is preferably 95% by weight or more, more preferably 99% by weight, based on the total amount of the monomer (1) to be subjected to the polymerization. As mentioned above, it may be 100% by weight. That is, the entire amount of the monomer (1) to be subjected to the polymerization may be collectively added to the reactor before or at the start of the polymerization.

In the above production method, it is preferable to add 90% by weight or more of VdF to the reactor with respect to the total amount of VdF to be subjected to the polymerization before or at the start of the polymerization. By adding most of the VdF to be subjected to the polymerization to the reactor before the start of the polymerization or at the start of the polymerization, a copolymer having a high melting point and excellent heat resistance can be obtained more easily.

The amount of VdF added before or at the start of the polymerization is preferably 95% by weight or more, more preferably 99% by weight or more, and 100% by weight, based on the total amount of VdF to be subjected to the polymerization. May be good. That is, the entire amount of VdF to be subjected to the polymerization may be collectively added to the reactor before or at the start of the polymerization.

In the above production method, VdF and the monomer (1) are polymerized at a polymerization temperature of 0 to 55 ° C. If the polymerization temperature is too high, a copolymer having a high melting point and excellent heat resistance cannot be obtained, and if the polymerization temperature is too low, the polymerization does not proceed smoothly and the production efficiency of the copolymer is lowered. The polymerization temperature is preferably 30 ° C. or higher, more preferably 35 ° C. or higher, still more preferably 40 ° C. or higher, and preferably 50 ° C. or lower because a copolymer having a high melting point can be more easily produced. Yes, more preferably 45 ° C. or lower.

In the above production method, the polymerization temperature may be adjusted within the above range at any time of polymerization. From the viewpoint that a copolymer having a high melting point and excellent heat resistance can be more easily obtained, it is preferable to adjust the polymerization temperature within the above range at least at the start of polymerization, and to polymerize within the above range at the start of polymerization. It is more preferable to adjust the temperature and further adjust the polymerization temperature within the above range in the entire period until the completion of the polymerization.

In the above production method, it is preferable that the maximum pressure (maximum ultimate pressure) reached during polymerization is 4.38 MPa or more. The maximum pressure is preferably 4.80 MPa or more, more preferably 5.30 MPa or more, and further preferably 5.80 MPa or more. The upper limit of the maximum pressure is not particularly limited, but if the pressure is too high, a reactor with high pressure resistance is required, and the design and manufacture of the reactor are costly. Therefore, the upper limit of the maximum pressure is preferably 12.00 MPa or less, more preferably 10.00 MPa or less, and further preferably 7.00 MPa or less from the viewpoint of safe and low-cost production.

In the above production method, the polymerization pressure during polymerization may fluctuate. The maximum pressure (maximum ultimate pressure) is the highest internal pressure of the reactor (gauge pressure) reached during polymerization. The maximum pressure is determined by the polymerization temperature, VdF in the reactor, the density of the monomer (1), and the like.

Since a copolymer having a high melting point can be efficiently produced, it is also preferable to polymerize VdF and the monomer (1) under the condition that VdF is in a supercritical state. The critical temperature of VdF is 30.1 ° C., and the critical pressure is 4.38 MPa.

Since a copolymer having a high melting point can be efficiently produced, VdF and the monomer (1) are supplied to the reactor so that the density of the VdF and the monomer (1) in the reactor is sufficiently high. It is also preferable. The density of VdF and the monomer (1) in the reactor at the initial polymerization temperature is preferably 0.20 g / cm ³ or more, more preferably 0.25 g / cm ³ or more, and further preferably 0. It is .30 g / cm ³ or more, and the upper limit is not particularly limited, but if the density is too high, the pressure change in the reactor tends to be too large due to the change in the temperature inside the reactor, so it is produced safely. From the viewpoint, 0.70 g / cm ³ or less is preferable. The density of VdF and the monomer (1) in the reactor is the supply amount (g) of the monomer mixture supplied to the reactor, from the internal volume of the reactor (cm ³ ) to the volume of water (cm ³ ). Can be obtained by dividing by a value obtained by subtracting.

VdF and the monomer (1) are supplied to the reactor in a composition ratio such that a copolymer having a desired monomer composition can be obtained. The content of the monomer (1) unit of the copolymer obtained by the production method of the present disclosure is 3.0 to 25.0% by mass with respect to all the monomer units constituting the copolymer. .. By adjusting the content of the monomer (1) unit of the copolymer within this range, a copolymer having a high melting point and excellent heat resistance can be obtained. Further, the obtained copolymer has both bending resistance and flexibility. Moreover, by using the obtained copolymer, an electrode mixture whose viscosity does not easily increase can be obtained, and an electrode material layer having excellent electrolytic solution swelling resistance can be obtained. The content of the monomer (1) unit of the copolymer is preferably 4.0% by mass or more, more preferably 5.0% by mass or more, and preferably 24.0% by mass or less. More preferably, it is 23.0% by mass or less.

In the above production method, a monomer copolymerizable with VdF and the monomer (1) other than VdF and the monomer (1) may be further polymerized. Examples of the monomer copolymerizable with VdF and the monomer (1) include a fluorinated monomer (however, excluding VdF and the monomer (1)), a non-fluorinated monomer, and the like. Fluorinated monomers are preferred. Examples of the fluorinated monomer include tetrafluoroethylene, vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene, fluoroalkyl vinyl ether, hexafluoropropylene, (perfluoroalkyl) ethylene and the like. Examples of the non-fluorinated monomer include ethylene and propylene. The content of the VdF of the copolymer and the monomer unit copolymerizable with the monomer (1) is preferably 0 to 5.0% by mass, more preferably 0 to 3.0% by mass. , More preferably 0 to 1.0% by mass. It is also preferable that the copolymer consists of only VdF units and monomer (1) units.

As the polymerization method, suspension polymerization, emulsion polymerization, solution polymerization and the like can be adopted, but suspension polymerization and emulsion polymerization are preferable from the viewpoint of ease of post-treatment and the like.

In the above polymerization, a polymerization initiator, a surfactant, a chain transfer agent and a solvent can be used, and conventionally known ones can be used for each. As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, for example,
Dialkyl peroxy carbonates such as dinormal propyl peroxy dicarbonate, diisopropyl peroxy dicarbonate, disec-butyl peroxy dicarbonate;
t-Butylperoxyisobutyrate, t-butylperoxypivalate, t-hexylperoxy2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, 1,1,3,3- Peroxyesters such as tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxypivalate;
Dialkyl peroxides such as dit-butyl peroxide;
Di [fluoro (or fluorochloro) acyl] peroxides;
Etc. are typical examples.

Di [fluoro (or fluorochloro) acyl] peroxides are represented by [(RfCOO)-] ₂ (Rf is a perfluoroalkyl group, ω-hydroperfluoroalkyl group or fluorochloroalkyl group). Peroxide can be mentioned.

Examples of di [fluoro (or fluorochloro) acyl] peroxides include di (ω-hydro-dodecafluorohexanoyl) peroxide, di (ω-hydro-tetradecafluoroheptanoyl) peroxide, and di (ω). -Hydro-hexadecafluorononanoyl) peroxide, di (perfluorobutyryl) peroxide, di (perfluoropaleryl) peroxide, di (perfluorohexanoyl) peroxide, di (perfluoroheptanoyl) par Oxide, di (perfluorooctanoyl) peroxide, di (perfluorononanoyl) peroxide, di (ω-chloro-hexafluorobutyryl) peroxide, di (ω-chloro-decafluorohexanoyl) peroxide, Di (ω-chloro-tetradecafluorooctanoyl) peroxide, ω-hydro-dodecafluoroheptanoyl-ω-hydrohexadecafluorononanoyl-peroxide, ω-chloro-hexafluorobutyryl-ω-chloro-deca Fluorohexanoyl-peroxide, ω-hydrododecafluoroheptanoyl-perfluorobutyryl-peroxide, di (dichloropentafluorobutanoyl) peroxide, di (trichlorooctafluorohexanoyl) peroxide, di (tetrachloroun) Examples thereof include decafluorooctanoyl) peroxide, di (pentachlorotetradecafluorodecanoyl) peroxide, and di (undecachlorotriacontafluorodocosanoyl) peroxide.

The water-soluble radical polymerization initiator may be a known water-soluble peroxide, for example, ammonium salts such as persulfate, perboric acid, perchloric acid, perphosphoric acid and percarbonate, potassium salts and sodium salts. , Organic peroxides such as disuccinic acid peroxide and diglutaric acid peroxide, t-butyl permalate, t-butyl hydroperoxide and the like. A reducing agent such as sulfates may be used in combination with the peroxide, and the amount used may be 0.1 to 20 times the amount of the peroxide.

As a polymerization method, the polymerization can be smoothly started at the above-mentioned polymerization temperature, and a copolymer having a high melting point and excellent heat resistance can be easily produced. Therefore, it is suspended in the presence of a peroxide polymerization initiator. A method of turbid polymerization and a method of emulsifying polymerization in the presence of a redox polymerization initiator are preferable. Examples of the peroxide polymerization initiator include the above-mentioned oil-soluble peroxides. Examples of the redox polymerization initiator include the above-mentioned combination of the peroxide and the reducing agent.

As the surfactant, a known surfactant can be used, and for example, a nonionic surfactant, an anionic surfactant, a cationic surfactant, or the like can be used. Among them, a fluorine-containing anionic surfactant is preferable, and an ether bond may be contained (that is, an oxygen atom may be inserted between carbon atoms), and a linear or branched fluorine-containing detergent having 4 to 20 carbon atoms is preferable. Anionic surfactants are more preferred. The amount of the surfactant added (against the solvent) is preferably 50 to 5000 ppm.

By polymerizing in the presence of a chain transfer agent, the solution viscosity, weight average molecular weight, etc. of the obtained copolymer can be appropriately adjusted, and a copolymer having a high melting point and excellent heat resistance can be easily obtained. Can be done. Examples of the chain transfer agent include hydrocarbons such as ethane, isopentan, n-hexane and cyclohexane; aromatics such as toluene and xylene; ketones such as acetone; acetates such as ethyl acetate and butyl acetate; methanol. , Alcohols such as ethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride, methyl chloride and the like.

The amount of the chain transfer agent added may vary depending on the magnitude of the chain transfer constant of the chain transfer agent, but is usually 0.01 to 20% by mass with respect to the solvent.

Examples of the solvent include water, a mixed solvent of water and alcohol, and the like.

In polymerization such as suspension polymerization, a fluorine-based solvent may be used in addition to water. Fluorine-based solvents include hydrochlorofluoroalkanes such as CH ₃ CClF ₂ , CH ₃ CCl ₂ F, CF ₃ CF ₂ CCl ₂ H, CF ₂ ClCF ₂ CF HCl; CF ₂ ClCFClCF ₂ CF ₃ , CF ₃ CFClCFClCF ₃ , etc. Chlorofluoroalkanes; perfluoroalkanes such as perfluorocyclobutane, CF ₃ CF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ ; CF ₂ HCF ₂ CF ₂ CF ₂ H, CF ₃ CFHCF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ H, CF ₃ CF ₂ CFHCF ₂ CF ₃ , CF ₃ CFHC FHCF ₂ CF ₃ , CF ₂ HCF ₂ CF ₂ CF ₂ CF ₂ H, CF ₂ HCFHCF ₂ CF ₂ CF ₃ , CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ H, CF ₃ CH (CF ₃ ) CF ₃ CF ₂ CF ₃ , CF ₃ CF (CF) ₃ ) CFHCF ₂ CF ₃ , CF ₃ CF (CF ₃ ) CFHC HCF ₃ , CF ₃ CH (CF ₃ ) CFHCF ₂ CF ₃ , CF ₂ HCF ₂ CF ₂ CF ₂ CF ₂ CF ₂ H, CF ₃ CF ₂ CF ₂ CF Hydrofluorocarbons such as ₂ CH ₂ CH ₃ , CF ₃ CH ₂ CF ₂ CH ₃ ; F (CF ₂ ) ₄ OCH ₃ , F (CF ₂ ) ₄ OC ₂ H ₅ , (CF ₃ ) ₂ CFOCH ₃ , F ( CF ₂ ) ₃ OCH ₃ and other (perfluoroalkyl) alkyl ethers; CF ₃ CH ₂ OCF ₂ CHF ₂ , CHF ₂ CF ₂ CH ₂ OCF ₂ CHF ₂ , CF ₃ CF ₂ CH ₂ OCF ₂ CHF ₂ and other hydrofluorocarbons Examples thereof include alkyl ethers, and among them, perfluoroalkanes are preferable. The amount of the fluorinated solvent used is preferably 10 to 100% by mass with respect to the solvent from the viewpoint of suspension and economy.

In suspension polymerization, suspending agents such as methyl cellulose, methoxylated methyl cellulose, propoxylated methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyethylene oxide and gelatin can be used. The amount of the suspending agent added (against the solvent) is preferably 0.005 to 1.0% by mass, more preferably 0.01 to 0.4% by mass.

As the polymerization initiator used for suspension polymerization, diisopropyl peroxydicarbonate, dinormal propyl peroxy dicarbonate, dinormal heptafluoropropyl peroxy dicarbonate, di (secondary butyl) peroxy carbonate, isobutyryl peroxide, di Examples thereof include (chlorofluoroacyl) peroxide, di (perfluoroacyl) peroxide, t-butylperoxypivalate, and t-amylperoxypivalate. The amount used is preferably 0.1 to 5% by mass with respect to the total amount of the monomers. By adjusting the amount of the polymerization initiator added, the solution viscosity, weight average molecular weight, etc. of the obtained copolymer can be appropriately adjusted.

In suspension polymerization, the degree of polymerization of the obtained polymer is obtained by adding a chain transfer agent such as ethyl acetate, methyl acetate, acetone, methanol, ethanol, n-propanol, acetaldehyde, propylaldehyde, ethyl propionate, and carbon tetrachloride. May be adjusted. The amount used is usually 0.1 to 5% by mass, preferably 0.5 to 3% by mass, based on the total amount of the monomers. By adjusting the amount of the chain transfer agent added, the solution viscosity, weight average molecular weight, etc. of the obtained copolymer can be appropriately adjusted.

The total amount of the monomers charged is 1: 1 to 1:10, preferably 1: 2 to 1: 5 in terms of the total amount of monomers: mass ratio of water.

When an aqueous dispersion containing the copolymer is obtained by the polymerization reaction after the completion of the polymerization, the copolymer can be recovered by coagulating, washing and drying the copolymer contained in the aqueous dispersion. .. When the copolymer is obtained as a slurry by the polymerization reaction, the copolymer can be recovered by taking out the slurry from the reactor, washing the slurry, and drying the slurry. By drying, the copolymer can be recovered in the form of powder.

The copolymer of the present disclosure and the copolymer obtained by the above-mentioned production method have both bending resistance and flexibility, and are excellent in heat resistance. Therefore, films, sheets, tubes, melt spinning, and knots are used. It can be suitably used as a coating agent or the like.

(Binder)
The copolymer of the present disclosure (hereinafter, may be referred to as a copolymer (1)) has both bending resistance and flexibility, is excellent in heat resistance, and is an electrode mixture whose viscosity does not easily increase. It can be suitably used as a binder because an electrode material layer having excellent swelling resistance to the electrolytic solution can be obtained. By using the binder containing the copolymer of the present disclosure as a binder for forming electrodes of secondary batteries, capacitors, etc., an electrode mixture whose viscosity does not easily increase can be obtained, and an electrolytic solution resistant solution can be obtained. An electrode material layer having excellent swellability can be obtained. Therefore, the binder of the present disclosure is suitable as a binder for batteries.

The binder of the present disclosure may contain a polymer other than the above-mentioned copolymer (1). Other polymers include fluoropolymers (excluding copolymer (1)), polymethacrylate, polymethylmethacrylate, polyacrylonitrile, polyimide, polyamide, polyamideimide, polycarbonate, styrene rubber, butadiene rubber, and styrene butadiene rubber. , Polyacrylic acid and the like.

Among the other polymers, a fluoropolymer (however, excluding the copolymer (1)) is preferable, and a polyvinylidene fluoride (however, excluding the copolymer (1)) and a vinylidene fluoride polymer (excluding the copolymer (1)) are preferable. However, at least one selected from the group consisting of the copolymer (1) is more preferable, and polyvinylidene fluoride (however, the copolymer (1) is excluded) is further preferable.

It is also preferable that the binder of the present disclosure further contains polyvinylidenefluoride (however, excluding the copolymer (1)). Polyvinylidene fluoride (PVdF) is a polymer containing VdF units, and is a polymer different from the above-mentioned copolymer (1). PVdF may be a VdF homopolymer consisting only of VdF units, or may be a polymer containing VdF units and a monomer unit copolymerizable with VdF.

In the above PVdF, examples of the monomer copolymerizable with VdF include a fluorinated monomer and a non-fluorinated monomer, and a fluorinated monomer is preferable. The fluorinated monomer is preferably a monomer other than the monomer (1), for example, vinyl fluoride, trifluoroethylene, chlorotrifluoroethylene (CTFE), fluoroalkyl vinyl ether, hexafluoro. Examples thereof include propylene (HFP) and (perfluoroalkyl) ethylene. Examples of the non-fluorinated monomer include ethylene and propylene.

In the above PVdF, as the monomer copolymerizable with VdF, at least one fluorinated monomer selected from the group consisting of CTFE, fluoroalkyl vinyl ether and HFP is preferable, and from CTFE, HFP and fluoroalkyl vinyl ether. At least one fluorinated monomer selected from the above group is more preferable.

In the above PVdF, the content of the monomer unit copolymerizable with VdF is preferably 0 to 5.0 mol%, more preferably 0 to 3.0 mol% with respect to all the monomer units. Is. In the above PVdF, the content of the fluorinated monomer unit (excluding the VdF unit) is preferably less than 5.0 mol%, more preferably 3.0, with respect to all the monomer units. It is less than mol%, more preferably less than 1.0 mol%.

In the present disclosure, the composition of PVdF can be measured, for example, by ¹⁹ F-NMR measurement.

The PVdF may have a polar group. By using the copolymer (1) and PVdF having a polar group as the binder, it is possible to form a more excellent electrode material layer due to the adhesion to the metal foil.

The polar group is not particularly limited as long as it is a functional group having polarity, but from a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfate group, a phosphoric acid group, an amino group, an amide group and an alkoxy group. At least one selected from the group consisting of a carbonyl group-containing group, an epoxy group and a hydroxy group is more preferable, and a carbonyl group-containing group is even more preferable. The hydroxy group does not include a hydroxy group constituting a part of the carbonyl group-containing group. The amino group is a monovalent functional group obtained by removing hydrogen from ammonia, a primary or a secondary amine.

The carbonyl group-containing group is a functional group having a carbonyl group (-C (= O)-). The carbonyl group-containing group is preferably a group represented by the general formula: -COOR (R represents a hydrogen atom, an alkyl group or a hydroxyalkyl group) or a carboxylic acid anhydride group, and is represented by the general formula: -COOR. The groups to be treated are more preferred. The number of carbon atoms of the alkyl group and the hydroxyalkyl group is preferably 1 to 16, more preferably 1 to 6, and further preferably 1 to 3. General formula: As a group represented by -COOR, specifically, -COOCH ₂ CH ₂ OH, -COOCH ₂ CH (CH ₃ ) OH, -COOCH (CH ₃ ) CH ₂ OH, -COOH, -COOCH ₃ , -COOC ₂ H ₅ and the like. General formula: When the group represented by -COOR is -COOH or contains -COOH, -COOH may be a carboxylate such as a carboxylic acid metal salt or a carboxylic acid ammonium salt.

The carbonyl group-containing group has a general formula: -X-COOR (X is mainly composed of 2 to 15 atoms, and the molecular weight of the atomic group represented by X is preferably 350 or less. R is a hydrogen atom. , An alkyl group or a hydroxyalkyl group). The number of carbon atoms of the alkyl group and the hydroxyalkyl group is preferably 1 to 16, more preferably 1 to 6, and further preferably 1 to 3.

The amide group includes a group represented by the general formula: -CO-NRR'(R and R'independently represent a hydrogen atom or a substituted or unsubstituted alkyl group), or a general formula:-. CO-NR "-(R" represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted phenyl group) is preferable.

The polar group can be introduced into PVdF by polymerizing VdF and a monomer having the polar group (hereinafter referred to as a polar group-containing monomer), or PVdF and a compound having the polar group. Although it can be introduced into PVdF by reacting with, it is preferable to polymerize VdF and the above-mentioned polar group-containing monomer from the viewpoint of productivity.

By polymerizing VdF and the above-mentioned polar group-containing monomer, PVdF containing a VdF unit and a unit based on the polar group-containing monomer (hereinafter referred to as a polar group-containing monomer unit) can be obtained. That is, PVdF preferably contains the above-mentioned polar group-containing monomer unit. The content of the polar group-containing monomer unit is preferably 0.001 to 5.0 mol%, more preferably 0.01 to 3.0 mol%, based on all the monomer units. , More preferably 0.10 to 1.5 mol%.

In the present disclosure, the content of the polar group-containing monomer unit in PVdF can be measured, for example, by acid-base titration of the acid group when the polar group is an acid group such as a carboxylic acid.

Examples of the polar group-containing monomer include hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate and 2-hydroxypropyl acrylate; (meth) acrylic acid, crotonic acid, vinyl acetic acid (3-butenoic acid), and 3-pentenoic acid. , 4-Pentenoic acid, 3-hexenoic acid, 4-heptenoic acid and other unsaturated monobasic acids; maleic acid, maleic anhydride, citraconic acid, unsaturated dibasic acid such as citraconic acid and the like; Alkylidene malonic acid ester; vinylcarboxyalkyl ether such as vinylcarboxymethyl ether and vinylcarboxyethyl ether; carboxyalkyl (meth) acrylate such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; acryloyloxyethyl succinic acid and methacryloyloxy. (Meta) acryloyloxyalkyldicarboxylic acid esters such as ethylsuccinic acid, acryloyloxyethylphthalic acid, acryloyloxypropylsuccinic acid, methacryloyloxyethylphthalic acid; maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester, citracon Monoesters of unsaturated dibasic acids such as acid monoethyl esters; and the like.

When PVdF is reacted with the compound having the polar group to introduce the polar group into PVdF, the polar group-containing monomer or the group reactive with PVdF is used as the compound having the polar group. A silane-based coupling agent or a titanate-based coupling agent having a hydrolyzable group can be used. The hydrolyzable group is preferably an alkoxy group. When a coupling agent is used, it can be added to PVdF by reacting with PVdF dissolved or swollen in a solvent.

As the PVdF, it is also possible to use a PVdF obtained by partially defluorinating the PVdF with a base and then further reacting the partially defluorinated hydrogenated PVdF with an oxidizing agent. Examples of the oxidizing agent include hydrogen peroxide, hypochlorite, palladium halide, chromium halide, alkali metal permanganate, peracid compound, alkyl peroxide, alkyl persulfate and the like.

The content of PVdF in VdF units is preferably more than 95.0 mol% with respect to all monomer units because it is possible to form a more excellent electrode material layer due to its flexibility and adhesion to metal foil. It is more preferably more than 97.0 mol%, still more preferably more than 99.0 mol%.

Further, the content of VdF unit of PVdF is preferably 95.0 to 95.0 to all monomer units because it is possible to form a more excellent electrode material layer due to its flexibility and adhesion to the metal foil. It is 99.999 mol%, more preferably more than 95.0 mol%, further preferably 97.0 mol% or more, particularly preferably 98.5 mol% or more, and more preferably 99.99. It is mol% or less, more preferably 99.90 mol% or less.

The weight average molecular weight (in terms of polystyrene) of PVdF is preferably 50,000 to 3,000,000, more preferably 80,000 or more, further preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably 2400000 or less. It is more preferably 220000 or less, and particularly preferably 20000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using N, N-dimethylformamide as a solvent. Further, since it is possible to form an electrode material layer having excellent flexibility and adhesion to a metal foil, the weight average molecular weight of PVdF (A) may be 1,000,000 or more, and may be 1500,000 or more. May be good.

The number average molecular weight (in terms of polystyrene) of PVdF is preferably 20000 to 15000000, more preferably 40,000 or more, further preferably 70,000 or more, particularly preferably 140000 or more, and more preferably 140000 or less. It is more preferably 120000 or less, and particularly preferably 110000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

The melting point (secondary melting point) of PVdF is preferably 100 to 240 ° C. The melting point is raised from 30 ° C. to 220 ° C. at a rate of 10 ° C./min using a differential scanning calorimetry (DSC) device, then lowered to 30 ° C. at 10 ° C./min, and then again at 10 ° C./min. It is obtained as the temperature with respect to the maximum value in the heat of fusion curve when the temperature is raised to 220 ° C. at a rate.

PVdF can be produced by a conventionally known method such as solution polymerization or suspension polymerization by appropriately mixing VdF, the above-mentioned polar group-containing monomer, and an additive such as a polymerization initiator.

The storage elastic modulus of PVdF at 30 ° C. is preferably 2000 MPa or less, more preferably 1800 MPa or less.
The storage elastic modulus of PVdF at 60 ° C. is preferably 1500 MPa or less, more preferably 1300 MPa or less.
The storage elastic modulus of PVdF at 30 ° C. is preferably 1000 MPa or more, more preferably 1100 MPa or more.
The storage elastic modulus of PVdF at 60 ° C. is preferably 600 MPa or more, more preferably 700 MPa or more.
The storage elastic modulus of PVdF can be measured by the same method as the storage elastic modulus of the copolymer (1).

In the binder of the present disclosure, the mass ratio of the copolymer (1) to polyvinylidene fluoride (copolymer (1) / polyvinylidene fluoride) is preferably 99/1 to 1/99. , More preferably 97/3 or less, still more preferably 95/5 or less, still more preferably 3/97 or more, still more preferably 5/90 or more.

The binder of the present disclosure may contain a vinylidene fluoride polymer (excluding the copolymer (1)). Examples of the vinylidene fluoride (VdF) polymer (excluding the copolymer (1)) include polymers containing VdF units and fluorinated monomer units (excluding VdF units).

The fluorinated monomer (however, excluding VdF) is preferably a monomer other than the monomer (1), for example, tetrafluoroethylene (TFE), vinyl fluoride, trifluoroethylene, chloro. Examples thereof include trifluoroethylene (CTFE), fluoroalkyl vinyl ether, hexafluoropropylene (HFP), (perfluoroalkyl) ethylene and the like. Among them, at least one selected from the group consisting of TFE, CTFE and HFP is preferable, and it is composed of TFE and HFP, because it is possible to form a more excellent electrode material layer due to its flexibility and adhesion to the metal foil. At least one selected from the group is more preferred, and TFE is particularly preferred.

The fluorinated monomer unit may or may not have a polar group.

The content of the VdF unit of the VdF polymer is preferably more than 50 mol% and 99 mol% or less with respect to all the monomer units. When the content of the VdF unit is in the above range, it is possible to form an electrode material layer having further excellent flexibility and adhesion to the metal foil.

As for the content of the VdF unit of the VdF polymer, since it is possible to form a more excellent electrode material layer due to its flexibility and adhesion to the metal foil, it is preferably 57.0 with respect to all the monomer units. More than mol%, more preferably 60.0 mol% or more, still more preferably 63.0 mol% or more, preferably 99.0 mol% or less, still more preferably 97.0 mol% or less. It is more preferably 95.0 mol% or less, particularly preferably 90.0 mol% or less, and most preferably 85.0 mol% or less.

The content of the fluorinated monomer unit (excluding the VdF unit) of the VdF polymer is not particularly limited, but it is possible to form a more excellent electrode material layer due to its flexibility and adhesion to the metal foil. Therefore, it is preferably 1.0 mol% or more, more preferably 3.0 mol% or more, still more preferably 5.0 mol% or more, and particularly preferably 10 with respect to all the monomer units. It is 0.0 mol% or more, most preferably 15.0 mol% or more, preferably less than 50 mol%, more preferably 43.0 mol% or less, still more preferably 40.0 mol% or less. Yes, particularly preferably 37.0 mol% or less.

In the present disclosure, the composition of the VdF polymer can be measured, for example, by ¹⁹ F-NMR measurement.

The VdF polymer may further contain a non-fluorinated monomer unit. The non-fluorinated monomer may be a non-fluorinated monomer having no polar group such as ethylene or propylene, or a non-fluorinated monomer having a polar group (hereinafter referred to as a polar group-containing monomer). ) Etc. can be mentioned.

When a non-fluorinated monomer having a polar group is used, a polar group is introduced into the VdF polymer, whereby even better adhesion between the positive electrode material layer and the current collector can be obtained. The polar group that the VdF polymer can have is at least selected from the group consisting of a carbonyl group-containing group, an epoxy group, a hydroxy group, a sulfonic acid group, a sulfate group, a phosphoric acid group, an amino group, an amide group and an alkoxy group. One is preferable, at least one selected from the group consisting of a carbonyl group-containing group, an epoxy group and a hydroxy group is more preferable, and a carbonyl group-containing group is further preferable. The hydroxy group does not include a hydroxy group constituting a part of the carbonyl group-containing group. The amino group is a monovalent functional group obtained by removing hydrogen from ammonia, a primary or a secondary amine.

The carbonyl group-containing group is a functional group having a carbonyl group (-C (= O)-). As the carbonyl group-containing group, a group represented by the general formula: -COOR (R represents a hydrogen atom, an alkyl group or a hydroxyalkyl group) or a carboxylic acid anhydride group is preferable. The number of carbon atoms of the alkyl group and the hydroxyalkyl group is preferably 1 to 16, more preferably 1 to 6, and further preferably 1 to 3. General formula: As a group represented by -COOR, specifically, -COOCH ₂ CH ₂ OH, -COOCH ₂ CH (CH ₃ ) OH, -COOCH (CH ₃ ) CH ₂ OH, -COOH, -COOCH ₃ , -COOC ₂ H ₅ and the like. General formula: When the group represented by -COOR is -COOH or contains -COOH, -COOH may be a carboxylate such as a carboxylic acid metal salt or a carboxylic acid ammonium salt.

Examples of the polar group-containing monomer include hydroxyalkyl (meth) acrylates such as hydroxyethyl acrylate and 2-hydroxypropyl acrylate; alkylidene malonate esters such as dimethyl metylidene malonate; vinyl carboxymethyl ether, vinyl carboxyethyl ether and the like. Vinyl carboxyalkyl ethers; carboxyalkyl (meth) acrylates such as 2-carboxyethyl acrylate and 2-carboxyethyl methacrylate; acryloyloxyethyl succinic acid, acryloyloxypropyl succinic acid, methacryloyloxyethyl succinic acid, acryloyloxyethyl phthalic acid, (Meta) acryloyloxyalkyl dicarboxylic acid esters such as methacryloyloxyethyl phthalic acid; monoesters of unsaturated dibasic acids such as maleic acid monomethyl ester, maleic acid monoethyl ester, citraconic acid monomethyl ester, citraconic acid monoethyl ester; general Equation (2):

(In the formula, R ¹ to R ³ independently represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. R ⁴ represents a single bond or a hydrocarbon group having 1 to 8 carbon atoms. Y ¹ (2); and the like represented by (representing an inorganic cation and / or an organic cation).

As the polar group-containing monomer unit that can be contained in the VdF polymer, a unit based on the monomer (2) represented by the general formula (2) is preferable.

In the general formula (2), Y ¹ represents an inorganic cation and / or an organic cation. Examples of the inorganic cation include cations such as H, Li, Na, K, Mg, Ca, Al and Fe. Examples of the organic cation include cations such as NH ₄ , NH ₃ R ⁵ , NH ₂ R _{52, NHR 5 3} ^, _and NR ⁵ ₄ (R ⁵ independently represents an alkyl group having 1 to ⁴ carbon atoms). Can be mentioned. As Y ¹ , H, Li, Na, K, Mg, Ca, Al, NH ₄ are preferable, H, Li, Na, K, Mg, Al, NH ₄ are more preferable, and H, Li, Al, NH ₄ are preferable. Is more preferable, and H is particularly preferable. Specific examples of the inorganic cation and the organic cation are described by omitting the reference numerals and valences for convenience.

In the general formula (2), R ¹ to R ³ independently represent a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms. The hydrocarbon group is a monovalent hydrocarbon group. The hydrocarbon group preferably has 4 or less carbon atoms. Examples of the hydrocarbon group include an alkyl group having the number of carbon atoms, an alkenyl group, an alkynyl group and the like, and a methyl group or an ethyl group is preferable. It is preferable that R ¹ and R ² are independently hydrogen atoms, methyl groups or ethyl groups, and R ³ is preferably hydrogen atoms or methyl groups.

In the general formula (2), R ⁴ represents a single bond or a hydrocarbon group having 1 to 8 carbon atoms. The above hydrocarbon group is a divalent hydrocarbon group. The hydrocarbon group preferably has 4 or less carbon atoms. Examples of the hydrocarbon group include the above-mentioned alkylene group having a carbon number of carbon atoms, an alkenylene group and the like, and among them, at least one selected from the group consisting of a methylene group, an ethylene group, an ethylidene group, a propyridene group and an isopropyridene group is selected. Preferred, a methylene group is more preferred.

Examples of the monomer (2) include (meth) acrylic acid and its salt, vinylacetic acid (3-butenoic acid) and its salt, 3-pentenoic acid and its salt, 4-pentenoic acid and its salt, and 3-hexenoic acid. And salts thereof, 4-heptenoic acid and salts thereof, and at least one selected from the group consisting of 5-hexenoic acid and salts thereof, preferably 3-butenoic acid and salts thereof, and 4-pentenoic acid and salts thereof. At least one selected from the group consisting of salts is more preferred.

The content of the polar group-containing monomer unit of the VdF polymer is preferably 0.05 to 2.0 mol%, more preferably 0.10 mol% or more, based on all the monomer units. It is more preferably 0.25 mol% or more, particularly preferably 0.40 mol% or more, and more preferably 1.5 mol% or less.

In the present disclosure, the content of the polar group-containing monomer unit in the VdF polymer can be measured, for example, by acid-base titration of the acid group when the polar group is an acid group such as a carboxylic acid.

Examples of the VdF polymer include VdF / TFE copolymer, VdF / HFP copolymer, VdF / TFE / HFP copolymer, VdF / TFE / (meth) acrylic acid copolymer, and VdF / HFP / (meth). ) Acrylic acid copolymer, VdF / CTFE copolymer, VdF / TFE / 4-pentenoic acid copolymer, VdF / TFE / 3-butenoic acid copolymer, VdF / TFE / HFP / (meth) acrylic acid Polymer, VdF / TFE / HFP / 4-pentenoic acid copolymer, VdF / TFE / HFP / 3-butenoic acid copolymer, VdF / TFE / 2-carboxyethyl acrylate copolymer, VdF / TFE / HFP / Examples thereof include 2-carboxyethyl acrylate copolymers, VdF / TFE / acryloyloxyethyl succinic acid copolymers, VdF / TFE / HFP / acryloyloxyethyl succinic acid copolymers and the like.

As the VdF polymer, the VdF unit, the TFE unit, and any non-fluorinated monomer unit can be formed because the electrode material layer can be formed more excellently due to its flexibility and adhesion to the metal foil. A VdF polymer consisting only of a single substance is preferable.

When the VdF polymer contains VdF units and TFE units, the molar ratio of VdF units to TFE units (VdF units / TFE units) is preferably more than 50/50 and 99/1 or less, more preferably 57. It is / 43 to 97/3, more preferably 60/40 to 95/5, particularly preferably 63/37 to 90/10, and most preferably 63/37 to 85/15.

The weight average molecular weight (in terms of polystyrene) of the VdF polymer is preferably 50,000 to 3,000,000, more preferably 80,000 or more, further preferably 100,000 or more, particularly preferably 200,000 or more, and more preferably 2400000 or less. It is more preferably 220000 or less, and particularly preferably 20000 or less. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

The number average molecular weight (in terms of polystyrene) of the VdF polymer is preferably 20000 to 15000000, more preferably 40,000 or more, further preferably 70,000 or more, particularly preferably 140000 or more, and more preferably 140000 or less. It is more preferably 120000 or less, and particularly preferably 110000 or less. The number average molecular weight can be measured by gel permeation chromatography (GPC) using dimethylformamide as a solvent.

The melting point (secondary melting point) of the VdF polymer is preferably 100 to 170 ° C, more preferably 110 to 165 ° C, and even more preferably 120 to 163 ° C. The melting point is raised from 30 ° C. to 220 ° C. at a rate of 10 ° C./min using a differential scanning calorimetry (DSC) device, then lowered to 30 ° C. at 10 ° C./min, and then again at 10 ° C./min. It is obtained as the temperature with respect to the maximum value in the heat of fusion curve when the temperature is raised to 220 ° C. at a rate.

The VdF polymer preferably has a breaking point elongation of 100% or more. The elongation at break point is more preferably 200% or more, further preferably 300% or more.

The break point elongation can be measured by the following method. That is, the VdF polymer solution obtained by dissolving the VdF polymer in N-methyl-2-pyrrolidone (NMP) so as to have a concentration of 10 to 20% by mass was cast on a glass plate and at 100 ° C. for 12 hours. It is dried and further dried under vacuum at 100 ° C. for 12 hours to obtain a film having a thickness of 50 to 100 μm. The film is punched into a dumbbell shape and the elongation at break at 25 ° C. is measured by an autograph.

The VdF polymer preferably has a storage elastic modulus of 1100 MPa or less at 30 ° C. and a storage elastic modulus of 500 MPa or less at 60 ° C.
The storage elastic modulus of the VdF polymer at 30 ° C. is more preferably 800 MPa or less, still more preferably 600 MPa or less.
The storage elastic modulus of the VdF polymer at 60 ° C. is more preferably 350 MPa or less.
The storage elastic modulus of the VdF polymer at 30 ° C. is preferably 100 MPa or more, more preferably 150 MPa or more, still more preferably 200 MPa or more.
The storage elastic modulus of the VdF polymer at 60 ° C. is preferably 50 MPa or more, more preferably 80 MPa or more, and further preferably 130 MPa or more.
The storage elastic modulus of the VdF polymer can be measured by the same method as the storage elastic modulus of the copolymer (1).

In the binder of the present disclosure, the mass ratio of the copolymer (1) to the polymer other than the copolymer (1) (copolymer (1) / other polymer) is preferably 99. It is 1/1 to 1/99, more preferably 97/3 or less, further preferably 95/5 or less, still more preferably 3/97 or more, still more preferably 5/95 or more.

In the binder of the present disclosure, the mass ratio of the copolymer (1) to the VdF polymer (copolymer (1) / VdF polymer) is preferably 99/1 to 1/99, and more. It is preferably 97/3 or less, more preferably 95/5 or less, more preferably 3/97 or more, still more preferably 5/95 or more.

The binder of the present disclosure can be suitably used as a material for forming a battery such as a secondary battery and a capacitor. The battery may be a primary battery, a storage battery (secondary battery), or a power storage element. The battery may be a non-aqueous electrolyte battery. The non-aqueous electrolyte battery includes all batteries including an electrolyte and a power generation element. Examples of the non-aqueous electrolyte battery include a lithium ion primary battery, a lithium ion secondary battery, a nickel hydrogen battery, a lithium ion capacitor, an electric double layer capacitor and the like.

Since the binder of the present disclosure can obtain an electrode mixture whose viscosity does not easily increase and can form an electrode material layer exhibiting sufficient electrolytic solution swelling resistance, it is used as a binder for batteries of batteries such as secondary batteries and capacitors. Suitable as a dressing agent. The binder of the present disclosure can also be used as a binder for the separator coating of a secondary battery.

The binder of the present disclosure is preferably a binder for non-aqueous electrolyte batteries. Further, the binder of the present disclosure may be a secondary binder. In the present disclosure, the secondary binder includes a binder used for a positive electrode, a negative electrode, and a separator of a secondary battery. The secondary battery is preferably a lithium ion secondary battery.

The binder of the present disclosure can also form an electrode mixture together with a powder electrode material, water or a non-aqueous solvent. The secondary battery to which the binder of the present disclosure is applied includes a positive electrode in which the positive electrode mixture is held in the positive electrode current collector, and a negative electrode and an electrolytic solution in which the negative electrode mixture is held in the negative electrode current collector. I have.

The electrode mixture of the present disclosure contains the above-mentioned binder, powder electrode material, and water or non-aqueous solvent. The electrode mixture of the present disclosure is preferably an electrode mixture for a non-aqueous electrolyte battery. The electrode mixture of the present disclosure may be an electrode mixture for a secondary battery, or may be an electrode mixture for a lithium ion secondary battery. Since the electrode mixture of the present disclosure contains the above-mentioned binder, the viscosity can be easily adjusted to be suitable for coating on a current collector even when the binder is contained in a high concentration. In addition, the viscosity does not easily increase even when stored for a long period of time, and an electrode material layer having excellent electrolytic solution swelling resistance can be formed. Further, since the electrode mixture of the present disclosure contains the above-mentioned binder, it is easy to adjust the viscosity to an appropriate level and improve the coatability, and the appropriate viscosity is maintained for a long period of time. Can be maintained.

The electrode mixture may be a positive electrode mixture used for producing a positive electrode, or may be a negative electrode mixture used for producing a negative electrode. The electrode material layer formed from the electrode mixture of the present disclosure may be a positive electrode material layer or a negative electrode material layer as long as it contains the above-mentioned binder and powder electrode material. ..

The powder electrode material is a powder electrode material used for a battery, and preferably contains an electrode active material. The electrode active material is divided into a positive electrode active material and a negative electrode active material. In the case of a lithium ion secondary battery, the positive electrode active material is not particularly limited as long as it can electrochemically store and release lithium ions, but a lithium composite oxide is preferable, and a lithium transition metal composite oxide is preferable. More preferred. As the positive electrode active material, a lithium-containing transition metal phosphoric acid compound is also preferable. It is also preferable that the positive electrode active material is a substance containing lithium and at least one transition metal, such as a lithium transition metal composite oxide and a lithium-containing transition metal phosphoric acid compound.

V, Ti, Cr, Mn, Fe, Co, Ni, Cu and the like are preferable as the transition metal of the lithium transition metal composite oxide, and a lithium-cobalt composite such as LiCoO ₂ is a specific example of the lithium transition metal composite oxide. Oxides, lithium-nickel composite oxides such as LiNiO ₂ , lithium-manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ , Li ₂ MnO ₃ , and transition metal atoms that are the main constituents of these lithium transition metal composite oxides. Examples thereof include those obtained by substituting a part of the above with other metals such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr and Si. The above-mentioned substitutions include lithium-nickel-manganese composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-cobalt-manganese composite oxide, lithium-manganese-aluminum composite oxide, and lithium-titanium. Examples thereof include composite oxides, and more specifically, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.85 Co _0.10 Al _0.05 O ₂ , LiNi _0.33 Co _0.33 Mn ₀ . _.33 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.6 Mn _0.2 Co _0.2 O ₂ , LiNi _0.8 Mn _0.1 Co _0.1 O ₂ , Examples thereof include LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O ₄ , Li ₄ Ti ₅ O ₁₂ , LiNi _0.82 Co _0.15 Al _0.03 O ₂ .

The transition metal of the lithium-containing transition metal phosphoric acid compound is preferably V, Ti, Cr, Mn, Fe, Co, Ni, Cu or the like, and specific examples of the lithium-containing transition metal phosphoric acid compound include, for example, LiFePO ₄ . Iron phosphates such as Li ₃ Fe ₂ (PO ₄ ) ₃ , LiFeP ₂ O ₇ , cobalt phosphates such as LiCo PO ₄ , and some of the transition metal atoms that are the main constituents of these lithium transition metal phosphate compounds are Al. , Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, Si and the like substituted with other metals.

In particular, from the viewpoint of high voltage, high energy density, charge / discharge cycle characteristics, etc., LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNi _0.82 Co _0.15 Al _0.03 O ₂ , LiNi _0.33 . Mn _0.33 Co _0.33 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.6 Mn _0.2 Co _0.2 O ₂ , LiNi _0.8 Mn _0.1 Co _0.1 O ₂ and LiFePO ₄ are preferable.

Further, as the lithium transition metal composite oxide, a lithium-nickel-based composite oxide is preferable, and the general formula (3):
General formula (3): Li _y Ni _1-x M _x O ₂
(In the formula, x is 0.01 ≦ x ≦ 0.5, y is 0.9 ≦ y ≦ 1.2, and M represents a metal atom (excluding Ni).)
The lithium-nickel composite oxide represented by is more preferable. The lithium transition metal composite oxide having such a high nickel content is beneficial for increasing the capacity of the secondary battery.

In the general formula (3), x is a coefficient satisfying 0.01 ≦ x ≦ 0.5, and a secondary battery having a higher capacity can be obtained. Therefore, 0.05 ≦ x ≦ 0. 4, more preferably 0.10 ≦ x ≦ 0.3.

In the general formula (3), examples of the metal atom of M include V, Ti, Cr, Mn, Fe, Co, Cu, Al, Zn, Mg, Ga, Zr, Si and the like. Examples of the metal atom of M include transition metals such as V, Ti, Cr, Mn, Fe, Co, and Cu, or the above transition metals and Al, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, and the like. Combinations with other metals such as Mg, Ga, Zr and Si are preferred.

Lithium transition metal composite oxides with a high nickel content include LiNi _0.80 Co _0.15 Al _0.05 O ₂ , LiNi _0.82 Co _0.15 Al _0.03 O ₂ , and LiNi _0.33 Mn ₀ . _.33 Co _0.33 O ₂ , LiNi _0.5 Mn _0.3 Co _0.2 O ₂ , LiNi _0.6 Mn _0.2 Co _0.2 O ₂ , LiNi _0.8 Mn _0.1 Co _0. At least one selected from the group consisting of ₁ O ₂ and LiNi _0.90 Mn _0.05 Co _0.05 O ₂ is preferable, and LiNi _0.82 Co _0.15 Al _0.03 O ₂ and LiNi ₀ are preferable. _.6 At least one selected from the group consisting of Mn _0.2 Co _0.2 O ₂ and LiNi _0.8 Mn _0.1 Co _0.1 O ₂ is more preferable.

Further, it is also possible to use a substance having a composition different from the substance constituting the main positive electrode active material attached to the surface of these positive electrode active materials. Surface adhering substances include aluminum oxide, silicon oxide, titanium oxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, bismuth oxide and other oxides, lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate and calcium sulfate. , Sulfates such as aluminum sulfate, carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate and the like.

These surface-adhering substances are, for example, dissolved or suspended in a solvent to be impregnated with the positive electrode active material and dried, and the surface-adhering substance precursor is dissolved or suspended in the solvent to be impregnated with the positive electrode active material and then heated. It can be attached to the surface of the positive electrode active material by a method of reacting with the above, a method of adding to the positive electrode active material precursor and firing at the same time, or the like.

The amount of the surface adhering substance is preferably 0.1 ppm or more, more preferably 1 ppm or more, further preferably 10 ppm or more, and the upper limit is preferably 20% or less, more preferably 10 in terms of mass with respect to the positive electrode active material. % Or less, more preferably 5% or less. The surface adhering substance can suppress the oxidation reaction of the non-aqueous electrolytic solution on the surface of the positive electrode active material and improve the battery life, but if the adhering amount is too small, the effect is not sufficiently exhibited. If it is too much, the resistance may increase because it inhibits the ingress and egress of lithium ions.

As the shape of the particles of the positive electrode active material, lumpy, polyhedron, spherical, elliptical spherical, plate-like, needle-like, columnar, etc. are used as conventionally used, but among them, the primary particles are aggregated to form secondary particles. It is preferably formed and the secondary particles have a spherical or elliptical spherical shape. Normally, the active material in the electrode expands and contracts with the charge and discharge of the electrochemical element, so that the stress tends to cause deterioration such as destruction of the active material and breakage of the conductive path. Therefore, it is preferable that the primary particles aggregate to form the secondary particles rather than the single particle active material containing only the primary particles because the stress of expansion and contraction is alleviated and deterioration is prevented. In addition, since spherical or elliptical spherical particles have less orientation during molding than plate-shaped equiaxed particles, the expansion and contraction of the electrode during charging and discharging is also smaller, and the electrode is manufactured. It is also preferable to mix it with the conductive agent because it is easy to mix uniformly.

The tap density of the positive electrode active material is usually 1.3 g / cm ³ or more, preferably 1.5 g / cm ³ or more, more preferably 1.6 g / cm ³ or more, and most preferably 1.7 g / cm ³ or more. .. When the tap density of the positive electrode active material is lower than the above lower limit, the amount of the dispersion medium required for forming the positive electrode material layer increases, and the required amount of the conductive agent and the binder increases, so that the positive electrode active material is applied to the positive electrode material layer. The filling rate may be constrained and the battery capacity may be constrained. By using the metal composite oxide powder having a high tap density, a high density positive electrode material layer can be formed. Generally, the larger the tap density is, the more preferable it is, and there is no particular upper limit. However, if it is too large, the diffusion of lithium ions through the non-aqueous electrolytic solution as a medium in the positive electrode material layer becomes rate-determining, and the load characteristics may be easily deteriorated. It is usually 2.5 g / cm ³ or less, preferably 2.4 g / cm ³ or less.

The tap density of the positive electrode active material is determined by passing a sieve having an opening of 300 μm and dropping a sample into a tapping cell of 20 cm ³ to fill the cell volume, and then a powder density measuring instrument (for example, a tap density manufactured by Seishin Corporation). ) Is used to perform tapping with a stroke length of 10 mm 1000 times, and the density obtained from the volume at that time and the weight of the sample is defined as the tap density.

The median diameter d50 (secondary particle diameter when the primary particles are aggregated to form secondary particles) of the particles of the positive electrode active material is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm. As described above, it is most preferably 3 μm or more, usually 20 μm or less, preferably 18 μm or less, more preferably 16 μm or less, and most preferably 15 μm or less. If it is below the above lower limit, a high bulk density product may not be obtained, and if it exceeds the upper limit, it takes time to diffuse lithium in the particles, resulting in deterioration of battery performance or positive electrode production of the battery, that is, as an active material. When a conductive agent, a binder, or the like is made into a slurry with a solvent and applied in a thin film form, problems such as drawing streaks may occur. Here, by mixing two or more kinds of positive electrode active materials having different median diameters d50, it is possible to further improve the filling property at the time of producing the positive electrode.

The median diameter d50 in the present disclosure is measured by a known laser diffraction / scattering type particle size distribution measuring device. When LA-920 manufactured by HORIBA is used as the particle size distribution meter, a 0.1 mass% sodium hexametaphosphate aqueous solution is used as the dispersion medium used for the measurement, and the measured refractive index is set to 1.24 after ultrasonic dispersion for 5 minutes. Is measured.

When the primary particles are aggregated to form secondary particles, the average primary particle diameter of the positive electrode active material is usually 0.01 μm or more, preferably 0.05 μm or more, and more preferably 0.08 μm or more. It is most preferably 0.1 μm or more, usually 3 μm or less, preferably 2 μm or less, still more preferably 1 μm or less, and most preferably 0.6 μm or less. If it exceeds the above upper limit, it is difficult to form spherical secondary particles, which adversely affects the powder filling property and greatly reduces the specific surface area, so that there is a high possibility that the battery performance such as output characteristics will deteriorate. be. On the contrary, if it is less than the above lower limit, problems such as inferior reversibility of charge / discharge may occur because the crystal is usually underdeveloped. The primary particle size is measured by observation using a scanning electron microscope (SEM). Specifically, in a photograph at a magnification of 10,000 times, the longest value of the intercept by the left and right boundary lines of the primary particles with respect to the horizontal straight line is obtained for any 50 primary particles, and the average value is obtained. Be done.

The BET specific surface area of the positive electrode active material is 0.2 m ² / g or more, preferably 0.3 m ² / g or more, more preferably 0.4 m ² / g or more, and 4.0 m ² / g or less, preferably 2 It is .5 m ² / g or less, more preferably 1.5 m ² / g or less. If the BET specific surface area is smaller than this range, the battery performance tends to deteriorate, and if it is large, the tap density does not easily increase, and a problem may easily occur in the coatability at the time of forming the positive electrode material layer.

The BET specific surface area is determined by using a surface meter (for example, a fully automatic surface area measuring device manufactured by Okura Riken) to pre-dry the sample at 150 ° C. for 30 minutes under nitrogen flow, and then the relative pressure of nitrogen with respect to atmospheric pressure. It is defined by the value measured by the nitrogen adsorption BET 1-point method by the gas flow method using a nitrogen helium mixed gas accurately adjusted so that the value is 0.3.

As a method for producing a positive electrode active material, a general method is used as a method for producing an inorganic compound. In particular, various methods can be considered for producing spherical or elliptical spherical active materials. For example, transition metal raw materials such as transition metal nitrates and sulfates and, if necessary, raw materials of other elements such as water can be used. It is dissolved or pulverized and dispersed in a solvent, the pH is adjusted while stirring to prepare and recover a spherical precursor, which is dried as necessary, and then Li such as LiOH, Li ₂ CO ₃ , Li NO ₃ and the like. A method of adding a source and firing at a high temperature to obtain an active material, a transition metal raw material such as transition metal nitrate, sulfuric acid, hydroxide, oxide, and if necessary, a solvent such as water for the raw material of other elements. It is dissolved or pulverized and dispersed in it, and dried and molded with a spray dryer or the like to form a spherical or elliptical spherical precursor, to which Li sources such as LiOH, Li ₂ CO ₃ , and LiNO ₃ are added and fired at a high temperature. A method for obtaining an active material, a transition metal raw material such as a transition metal nitrate, a sulfate, a hydroxide, an oxide, a Li source such as LiOH, Li ₂ CO ₃ , LiNO ₃ , and other substances as necessary. A method in which a raw material of an element is dissolved or pulverized and dispersed in a solvent such as water, dried and molded with a spray dryer or the like to form a spherical or elliptical spherical precursor, which is then fired at a high temperature to obtain an active material. And so on.

In the present disclosure, one type of positive electrode active material powder may be used alone, or two or more types having different compositions or different powder physical characteristics may be used in combination in any combination and ratio.

The negative electrode active material is not particularly limited as long as it can electrochemically store and release lithium ions, and is a carbonaceous material, a metal oxide such as tin oxide or silicon oxide, a metal composite oxide, or a single lithium substance. Examples thereof include lithium alloys such as lithium-aluminum alloys and metals capable of forming alloys with lithium such as Sn and Si. These may be used alone or in combination of two or more in any combination and ratio. Of these, carbonaceous materials or lithium composite oxides are preferably used from the viewpoint of safety.

The metal composite oxide is not particularly limited as long as it can occlude and release lithium, but it is preferable that titanium and / or lithium is contained as a constituent component from the viewpoint of high current density charge / discharge characteristics.

As a carbonaceous material,
(1) Natural graphite,
(2) Artificial carbonaceous material and artificial graphite material; carbonaceous material {for example, natural graphite, coal-based coke, petroleum-based coke, coal-based pitch, petroleum-based pitch, or an oxidation-treated product of these pitches, needle coke, pitch. Thermal decomposition products of coke and organic materials such as carbon materials partially graphitized, furnace black, acetylene black, pitch-based carbon fibers, carbonizable organic materials (for example, coal tar pitch from soft pitch to hard pitch, or dry distillation). Coal-based heavy oil such as liquefied oil, normal pressure residual oil, direct-retaining heavy oil of reduced pressure residual oil, crude oil, decomposition-based petroleum heavy oil such as ethylene tar produced by-product during thermal decomposition of naphtha, and acenaphtylene, Aromatic hydrocarbons such as decacyclene, anthracene and phenanthrene, N-ring compounds such as phenazine and acrydin, S-ring compounds such as thiophene and bithiophene, polyphenylene such as biphenyl and terphenyl, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, among these. Insolubilized products, organic polymers such as nitrogen-containing polyacrylonitrile and polypyrroleum, organic polymers such as sulfur-containing polythiophene and polystyrene, typified by cellulose, lignin, mannan, polygalactouronic acid, chitosan and saccharose. Natural polymers such as polysaccharides, thermoplastic resins such as polyphenylene sulfide and polyphenylene oxide, thermosetting resins such as furfuryl alcohol resin, phenol-formaldehyde resin, and imide resin) and carbonized products thereof, or carbonizable organic substances are benzene. , A solution dissolved in a low molecular weight organic solvent such as toluene, xylene, quinoline, n-hexane, and carbonaceous materials thereof}, which has been heat-treated at least once in the range of 400 to 3200 ° C.
(3) A carbonaceous material in which the negative electrode material layer is composed of at least two or more kinds of carbonaceous substances having different crystalline properties and / or has an interface in which the different crystalline carbonaceous substances are in contact with each other.
(4) A carbonaceous material in which the negative electrode material layer is composed of at least two kinds of carbonaceous materials having different orientations and / or has an interface in which the carbonaceous materials having different orientations are in contact with each other.
The one selected from the above is preferable because it has a good balance between initial irreversible capacity and high current density charge / discharge characteristics.

The content of the electrode active material (positive electrode active material or negative electrode active material) is preferably 40% by mass or more in the electrode mixture in order to increase the capacity of the obtained electrode.

The powder electrode material may further contain a conductive agent. Examples of the conductive agent include carbon blacks such as acetylene black and ketjen black, carbon materials such as graphite, carbon fibers, carbon nanotubes, carbon nanohorns, graphene and the like.

The ratio of the powder electrode material (active material and conductive agent) in the electrode mixture to the above-mentioned binder is usually about 80:20 to 99.5: 0.5 in terms of mass ratio, and is a powder component. It is determined in consideration of holding, adhesion to the current collector, and conductivity of the electrode.

In the electrode material layer formed on the current collector with the above-mentioned compounding ratio, the above-mentioned binder cannot completely fill the voids between the powder components, but the binder is used as a solvent. It is preferable to use water or a non-aqueous solvent that dissolves or disperses well because the binder is uniformly dispersed and knitted in the electrode material layer after drying, and the powder component is well retained.

The electrode mixture of the present disclosure contains water or a non-aqueous solvent. Examples of the non-aqueous solvent include nitrogen-containing organic solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide and dimethylformamide; ketone solvents such as acetone, methylethylketone, cyclohexanone and methylisobutylketone; ethyl acetate. , Ester solvent such as butyl acetate; Ether solvent such as tetrahydrofuran and dioxane; Further, general-purpose organic solvent having a low boiling point such as a mixed solvent thereof can be mentioned.

The electrode mixture of the present disclosure preferably contains a non-aqueous solvent from the viewpoint of excellent stability and coatability of the electrode mixture, and N-methyl-2-pyrrolidone and N, N- It preferably contains at least one selected from the group consisting of dimethylacetamide, and more preferably contains N-methyl-2-pyrrolidone.

The amount of water or non-aqueous solvent in the electrode mixture is determined in consideration of the coatability to the current collector, the thin film forming property after drying, and the like. Generally, the ratio of the binder to water or a non-aqueous solvent is preferably 0.5: 99.5 to 20:80 in terms of mass ratio.

In order to further improve the adhesion to the current collector, the electrode mixture is used, for example, acrylic resin such as polyacrylic acid, polymethacrylate, polymethylmethacrylate, polyimide, polyamide and polyamideimide resin, styrene rubber, etc. It may further contain butadiene rubber, styrene butadiene rubber and the like.

In order to improve the dispersion stability of the electrode slurry, a dispersant such as a resin-based surfactant having a surfactant action, a cationic surfactant, or a nonionic surfactant may be added to the electrode mixture.

The content of the binder in the electrode mixture is preferably 0.1 to 20% by mass, more preferably 0.2 to 10% by mass, still more preferably 0.2 to 10% by mass, based on the mass of the electrode mixture. It is 0.5 to 3% by mass.

Examples of the method for preparing the electrode mixture include a method in which the powder electrode material is dispersed and mixed in a solution or dispersion in which a binder is dissolved or dispersed in water or a non-aqueous solvent. Then, the obtained electrode mixture is uniformly applied to a current collector such as a metal foil or a metal net, dried, and pressed as necessary to form a thin electrode material layer on the current collector to form a thin-film electrode. do.

In addition, the binder and the powder of the electrode material may be mixed first, and then water or a non-aqueous solvent may be added to prepare an electrode mixture. In addition, the binder and the powder of the electrode material are heated and melted and extruded with an extruder to prepare a thin-film electrode mixture, which is then bonded onto a current collector coated with a conductive adhesive or a general-purpose organic solvent. It is also possible to manufacture an electrode sheet. Further, a solution or dispersion of the binder and the powder of the electrode material may be applied to the preformed electrode material. As described above, the method of application as a binder is not particularly limited.

The electrodes of the present disclosure contain the above-mentioned binder. The electrodes of the present disclosure are preferably electrodes for non-aqueous electrolyte batteries. Since the electrodes of the present disclosure contain the above-mentioned binder, the electrode does not crack even when the powder electrode material is thickly coated, wound, and pressed for high density, and the powder electrode material is dropped or collected. There is no peeling from the electric body. Further, the electrodes of the present disclosure are also excellent in electrolytic solution swelling resistance.

The electrode preferably includes a current collector and an electrode material layer containing the powder electrode material and the binder formed on the current collector. The electrode may be a positive electrode or a negative electrode, but is preferably a positive electrode.

Examples of the current collector (positive electrode current collector and negative electrode current collector) include metal foils such as iron, stainless steel, copper, aluminum, nickel, and titanium, or metal nets. Among them, aluminum foil or the like is preferable as the positive electrode current collector, and copper foil or the like is preferable as the negative electrode current collector.

The electrodes of the present disclosure can be manufactured, for example, by the method described above. Since the above-mentioned electrode mixture is excellent in coatability, an electrode having a smooth, uniform and thick electrode material layer is prepared by producing the electrode material layer provided with the electrode of the present disclosure by using the above-mentioned electrode mixture. Can be easily produced.

The secondary battery of the present disclosure includes the above-mentioned electrodes. The secondary battery of the present disclosure is preferably a non-aqueous electrolyte secondary battery. In the secondary battery of the present disclosure, at least one of the positive electrode and the negative electrode may be the above-mentioned electrode, and the positive electrode is preferably the above-mentioned electrode. The secondary battery is preferably a lithium ion secondary battery.

The secondary battery of the present disclosure preferably further comprises a non-aqueous electrolytic solution. The non-aqueous electrolyte solution is not particularly limited, but propylene carbonate, ethylene carbonate, butylene carbonate, γ-butyl lactone, 1,2-dimethoxyethane, 1,2-diethoxyethane, dimethyl carbonate, diethyl carbonate, etc. Known hydrocarbon-based solvents such as ethylmethyl carbonate; one or more of fluorine-based solvents such as fluoroethylene carbonate, fluoroether, and fluorinated carbonate can be used. As the electrolyte, any conventionally known electrolyte can be used, and LiClO ₄ , LiAsF ₆ , LiPF ₆ , LiBF ₄ , LiCl, LiBr, CH ₃ SO ₃ Li, CF ₃ SO ₃ Li, cesium carbonate and the like can be used.

Further, a separator may be interposed between the positive electrode and the negative electrode. As the separator, a conventionally known separator may be used, or a separator using the above-mentioned binder for coating may be used.

It is also preferable to use the above-mentioned binder for at least one of the positive electrode, the negative electrode and the separator of the secondary battery (preferably a lithium ion secondary battery).

The film for a secondary battery made of the above-mentioned binder is also one of the preferred forms of the present disclosure.

A laminate for a secondary battery having a base material and a layer made of the above-mentioned binder formed on the base material is also one of the preferred forms of the present disclosure. Examples of the base material include those exemplified as the above-mentioned current collector, known base materials (porous film and the like) used for separators of secondary batteries, and the like.

Since the electrodes of the present disclosure are excellent in flexibility and can form a secondary battery having excellent battery characteristics, they can be suitably used as electrodes for a wound type secondary battery. .. Further, the secondary battery of the present disclosure may be a winding type secondary battery.

The electrodes of the present disclosure are useful not only for lithium ion secondary batteries using the liquid electrolyte described above, but also for polymer electrolyte lithium secondary batteries for non-aqueous electrolyte secondary batteries. It is also useful for electric double layer capacitors.

The copolymer of the present disclosure may be in any form, and may be an aqueous dispersion, powder, pellets or the like.

The copolymer of the present disclosure and the copolymer obtained by the above-mentioned production method can be molded into various molded products. Further, the copolymer of the present disclosure can be easily molded into a molded product having a desired size and shape.

The molding method of the copolymer is not particularly limited, and examples thereof include compression molding, extrusion molding, blow molding, transfer molding, injection molding, roto molding, rotoline molding, and electrostatic coating.

The copolymers of the present disclosure include fillers, plasticizers, processing aids, mold release agents, pigments, flame retardants, lubricants, light stabilizers, weatherproof stabilizers, conductive agents, antistatic agents, UV absorbers, and antioxidants. It may be molded after mixing an agent, a foaming agent, a fragrance, an oil, a softening agent, a defluorinated hydrogen agent and the like. Examples of the filler include polytetrafluoroethylene, mica, silica, talc, serite, clay, titanium oxide, barium sulfate and the like. Examples of the conductive agent include carbon black and the like. Examples of the plasticizer include dioctylphthalic acid and pentaerythritol. Examples of the processing aid include carnauba wax, a sulfone compound, low molecular weight polyethylene, a fluorine-based auxiliary agent, and the like. Examples of the defluorinated hydrogenating agent include organic onium and amidines.

Since the copolymer of the present disclosure has both excellent bending resistance and high mechanical strength and exhibits excellent mechanical strength even at high temperatures, it is suitably used as a molded product used for various purposes. Can be done. The copolymer of the present disclosure can also be used as a powder coating material or a water-based coating material. Further, the copolymer of the present disclosure can also be used for building material steel plates, petroleum mining materials and the like.

Molded products include films, sheets, tubes, pipes, threads, fittings, valves, pumps, round bars, planks, bolts, nuts, insulating materials, wire coating materials, piezoelectric materials, pyroelectric materials, water treatment membranes, etc. It may be there. The yarn may be melt spinning (thread obtained by melt spinning), single fiber (monofilament), or the like.

Further, it can be suitably used as a molding material for the following molded products.

Fluid transfer materials for food manufacturing equipment such as food packaging films, lining materials for fluid transfer lines used in the food manufacturing process, packings, sealing materials, sheets, etc.;
Chemical transfer members such as chemical plugs, packaging films, lining materials for fluid transfer lines used in the chemical manufacturing process, packings, sealing materials, and sheets;
Internal lining members for chemical tanks and pipes in chemical plants and semiconductor factories;
O (corner) ring, tube, packing, valve core material, hose, sealant, etc. used for automobile fuel system and peripheral devices, hose, sealant, etc. fuel transfer member used for automobile AT equipment;
Other automobile parts such as flange gaskets, shaft seals, valve stem seals, sealing materials, hoses, automobile brake hoses, air conditioner hoses, radiator hoses, electric wire covering materials, etc. of carburetors used in automobile engines and peripheral devices;
Chemical transfer members for semiconductor devices such as O (corner) rings, tubes, packings, valve cores, hoses, sealing materials, rolls, gaskets, diaphragms, fittings, etc. of semiconductor manufacturing equipment;
Painting / ink materials such as painting rolls, hoses, tubes, and ink containers for painting equipment;
Food and beverage tubes or food and beverage hoses and other tubes, hoses, belts, packings, fittings and other food and beverage transfer members, food packaging materials, glass cooking equipment;
Waste liquid transportation materials such as tubes and hoses for waste liquid transportation;
High temperature liquid transportation members such as tubes and hoses for high temperature liquid transportation;
Steam piping members such as tubes and hoses for steam piping;
Anti-corrosion tape for piping such as tape wrapped around piping such as ship decks;
Various coating materials such as electric wire coating materials, optical fiber coating materials, transparent surface coating materials and backing agents provided on the light incident side surface of photovoltaic elements of solar cells;
Sliding members such as diaphragms of diaphragm pumps and various packings;
Agricultural film, various roofing materials, side walls, etc.
Interior materials used in the construction field, glass coverings such as nonflammable fire safety glass;
Lining materials such as laminated steel sheets used in the field of home appliances;

Although the embodiments have been described above, it will be understood that various changes in the forms and details are possible without deviating from the purpose and scope of the claims.

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

Each numerical value of the example was measured by the following method.

<Polymer composition of copolymer>
It was determined by ¹⁹ F-NMR measurement of the DMF-d7 solution of the copolymer using an NMR analyzer ( _VNS400 MHz manufactured by Agilent Technologies).

<Solution viscosity>
An NMP solution (5% by weight) of the copolymer was prepared. Using a B-type viscometer (TV-10M manufactured by Toki Sangyo Co., Ltd.), the rotor No. The viscosity of the NMP solution 10 minutes after the start of the measurement was measured under the conditions of M4 and a rotation speed of 6 rpm.

<Weight average molecular weight>
It was measured by gel permeation chromatography (GPC). Using Tosoh's AS-8010, CO-8020, column (three GMHHR-H connected in series) and Shimadzu's RID-10A, dimethylformamide (DMF) was used as a solvent at a flow rate of 1.0 ml / min. It was calculated from the data (reference: polystyrene) measured by flowing.

<Melting point>
Using a differential scanning calorimetry (DSC) device, the temperature is raised from 30 ° C to 220 ° C at a rate of 10 ° C / min, then lowered to 30 ° C at 10 ° C / min, and again at 220 ° C at a rate of 10 ° C / min. The temperature with respect to the maximum value in the heat of fusion curve when the temperature was raised to the maximum was obtained as the melting point.

<MIT value>
The copolymer was press-molded under the conditions of 230 ° C. and 5.0 MPa to prepare a film having a thickness of 0.20 to 0.23 mm. A sample was obtained from the obtained film by cutting it into strips having a width of 1.3 cm and a length of 90 mm. This is mounted on a MIT type bending fatigue tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and repeated bending tests are performed under conditions compliant with ASTM D-2176 (load 1.25 kg, bending angle 135 degrees, 175 times / minute). And the number of bends required to break was measured.

<Storage modulus>
The storage elastic modulus is a value measured at 25 ° C. and 120 ° C. by dynamic viscoelasticity measurement, and is a test piece having a length of 30 mm, a width of 5 mm, and a thickness of 50 to 300 μm by a dynamic viscoelastic device DVA220 manufactured by IT Measurement Control Co., Ltd. Was measured under the conditions of a tensile mode, a grip width of 20 mm, a measurement temperature of −30 ° C. to 160 ° C., a heating rate of 2 ° C./min, and a frequency of 10 Hz.

The test piece used for the measurement was formed by pressing a copolymer under the conditions of 230 ° C. and 5.0 MPa to prepare a film having a thickness of 50 to 300 μm, and the obtained film having a thickness of 50 to 300 μm was obtained. It was produced by cutting into a length of 30 mm and a width of 5 mm.

The rate of change in the storage elastic modulus at 25 ° C. and the storage elastic modulus at 120 ° C. was calculated by the following formula.
Rate of change (%) = [(storage elastic modulus at 25 ° C)-(storage elastic modulus at 120 ° C)] / (storage elastic modulus at 120 ° C) × 100

<Mandrel test>
A 2 cm × 10 cm test piece is prepared by cutting a positive electrode having a positive electrode material layer on both sides, and wound around a round bar having a diameter of 1.0 mm, a round bar having a diameter of 2.0 mm, and a round bar having a diameter of 3.0 mm. The positive electrode was visually observed to confirm the presence or absence of cracks in the positive electrode material layer, and evaluated according to the following criteria.
Φ1: No pinhole was confirmed in the positive electrode material layer even when wound around a round bar having a diameter of 1.0 mm.
Φ2: Pinholes were not confirmed in the positive electrode material layer even when wound around a round bar having a diameter of 2.0 mm, but pinholes were observed in the positive electrode material layer when wrapped around a round bar having a diameter of 1.0 mm.
Φ3: Pinholes were not confirmed in the positive electrode material layer even when wound around a round bar having a diameter of 3.0 mm, but pinholes were observed in the positive electrode material layer when wrapped around a round bar having a diameter of 2.0 mm.

<Electrolytic solution swelling resistance>
An NMP solution (8% by mass) of the copolymer was cast on a glass petri dish and vacuum dried at 100 ° C. for 6 hours to prepare a film having a thickness of 200 μm. The obtained film was cut into a size of 10 mmΦ and placed in a sample bottle containing an electrolytic solution (a solution in which LiPF ₆ was dissolved in a solvent of 3/7 (volume ratio) of ethylene carbonate and ethyl methyl carbonate at a concentration of 1 M). After allowing to stand at 60 ° C. for 1 week, the electrolytic solution swelling resistance was evaluated by determining the weight increase rate from the following formula.
Weight increase rate (%) = (film weight after immersion in electrolyte solution / film weight before immersion in electrolyte solution) x 100

<Slurry stability>
Using a B-type viscometer (TV-10M manufactured by Toki Sangyo Co., Ltd.), the rotor No. The viscosity of the positive electrode mixture was measured 10 minutes after the start of the measurement under the conditions of M4 and a rotation speed of 6 rpm. The viscosity change rate (Xn) is calculated by the following formula from the viscosity (η0) of the positive electrode mixture measured immediately after preparing the positive electrode mixture and the viscosity (ηn) 96 hours after the preparation of the mixture. Asked by.
Xn = ηn / η0 × 100 [%]

The viscosity change rate was evaluated according to the following criteria.
◯: The viscosity change rate (Xn) is less than 200%.
X: The viscosity change rate (Xn) is 200% or more.

Example 1
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 30 g of 2,3,3,3-tetrafluoropropene, 495 g of VdF, 4.0 g of ethyl acetate, and dinormal propylper. After charging 1 g of oxydicarbonate and raising the temperature to 45 ° C. over 1.5 hours, the temperature was maintained at 45 ° C. for 18 hours. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 18 hours after the temperature rise to 45 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

(Preparation of positive electrode mixture)
A positive electrode mixture (slurry) was prepared using the obtained copolymer powder. The obtained copolymer (binding agent) was dissolved in N-methyl-2-pyrrolidone (NMP) to prepare a copolymer solution having a concentration of 8% by mass. NMC811 (LiNi _0.8 Mn _0.1 Co _0.1 O ₂ ) (positive electrode active material), acetylene black (conductive aid) and copolymer (binder) solution were mixed using a stirrer. A mixed solution having a mass ratio of each component (positive electrode active material / conductive auxiliary agent / binder) of 97.0 / 1.5 / 1.5 was obtained. NMP was further added to the obtained mixed solution and mixed to prepare a positive electrode mixture having a solid content concentration of 70% by mass.

(Preparation of positive electrode)
After the obtained positive electrode mixture was uniformly applied to both sides of the positive electrode current collector (aluminum foil having a thickness of 20 μm) so that the coating amount was 22.5 mg / cm ² , the NMP was completely volatilized. , A positive electrode having a positive electrode material layer and a positive electrode current collector was produced by pressing with a roll press machine.

The characteristics of the copolymer, the positive electrode mixture and the positive electrode were evaluated by the above method. The results are shown in Table 1.

Example 2
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 40 g of 2,3,3,3-tetrafluoropropene, 495 g of VdF, 3.0 g of ethyl acetate, and dinormal propylper. After charging 1 g of oxydicarbonate and raising the temperature to 45 ° C. over 1.5 hours, the temperature was maintained at 45 ° C. for 19 hours. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 19 hours after the temperature rise to 45 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Using the obtained powder, a positive electrode mixture was prepared in the same manner as in Example 1 to prepare a positive electrode. By the above method, the characteristics of the copolymer, the positive electrode mixture and the positive electrode were evaluated. The results are shown in Table 1.

Example 3
In an autoclave with an internal volume of 2.0 liters, 1,010 g of pure water, 0.505 g of methyl cellulose, 49 g of 2,3,3,3-tetrafluoropropene, 360 g of VdF, 1.0 g of ethyl acetate, and dinormal propylper. After charging 0.8 g of oxydicarbonate and raising the temperature to 43 ° C. over 1.5 hours, the temperature was maintained at 43 ° C. for 14 hours. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 14 hours after the temperature rise to 43 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Example 4
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 110 g of 2,3,3,3-tetrafluoropropene, 440 g of VdF, and 1.5 g of dinormal propyl peroxydicarbonate. Was charged, the temperature was raised to 45 ° C. over 1.5 hours, and then 45 ° C. was maintained for 18 hours and 30 minutes. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 18 hours and 30 minutes after the temperature was raised to 45 ° C. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Comparative Example 1
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 14 g of 2,3,3,3-tetrafluoropropene, 495 g of VdF, 9.0 g of acetone, and dinormal propylperoxy. After charging 1 g of dicarbonate and raising the temperature to 42 ° C. over 1.5 hours, the temperature was maintained at 42 ° C. for 12 hours. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 18 hours after the temperature rise to 42 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Comparative Example 2
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 170 g of 2,3,3,3-tetrafluoropropene, 360 g of VdF, 1.5 g of ethyl acetate, and dinormal propylper. After charging 3.0 g of oxydicarbonate and raising the temperature to 45 ° C. over 1.5 hours, the temperature was maintained at 45 ° C. for 33 hours. The maximum ultimate pressure during this period was 5.2 MPaG.

Polymerization was completed 33 hours after the temperature rise to 45 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Comparative Example 3
1750 ml of pure water was placed in a 3 L stainless steel autoclave, replaced with nitrogen, slightly pressurized with vinylidene fluoride (VdF), adjusted to 80 ° C. with stirring at 600 rpm, and VdF was press-fitted to 1.80 MPa. A mixed solution monomer having a molar ratio of VdF and 2,3,3,3-tetrafluoropropene of 96.3 / 3.7 was press-fitted to 2.00 MPa. Polymerization was started by dissolving 0.417 g of ammonium persulfate in 10 ml of pure water and press-fitting it with nitrogen. The continuous monomer was supplied so that the pressure was maintained at 2.0 MPa, and after 3.2 hours, when 100 g of the continuous monomer was charged, the gas in the autoclave was released and cooled to recover 1869 g of the dispersion liquid. The solid content of the dispersion was 5.30% by mass. Aluminum sulfate was added to this dispersion, coagulated, and dried to obtain 99 g of a polymer.

Comparative Example 4
1750 ml of pure water was placed in a 3 L stainless steel autoclave, replaced with nitrogen, slightly pressurized with vinylidene fluoride (VdF), adjusted to 80 ° C. with stirring at 600 rpm, and VdF was press-fitted to 1.53 MPa. A mixed solution monomer having a molar ratio of VdF and 2,3,3,3-tetrafluoropropene of 91.2 / 8.8 was press-fitted to 2.00 MPa. Polymerization was started by dissolving 0.417 g of ammonium persulfate in 10 ml of pure water and press-fitting it with nitrogen. The continuous monomer was supplied so that the pressure was maintained at 2.0 MPa, and after 3.5 hours, when 100 g of the continuous monomer was charged, the gas in the autoclave was released and cooled to recover 1862 g of the dispersion liquid. The solid content of the dispersion was 5.32% by mass. Aluminum sulfate was added to this dispersion, coagulated, and dried to obtain 97 g of a polymer.

Comparative Example 5
Using PVdF (VdF homopolymer, trade name “KF7200”, manufactured by Kureha Corporation), a positive electrode mixture was prepared in the same manner as in Example 1 to prepare a positive electrode. The physical characteristics of PVdF were measured by the above method. In addition, the characteristics of the positive electrode mixture and the positive electrode were evaluated by the above method. The results are shown in Table 1.

Comparative Example 6
In an autoclave with an internal volume of 2.5 liters, 1,400 g of pure water, 0.7 g of methyl cellulose, 27 g of hexafluoropropylene, 495 g of VdF, 2.5 g of ethyl acetate, and 1.0 g of dinormal propyl peroxydicarbonate are charged. After raising the temperature to 44 ° C. over 1.5 hours, the temperature was maintained at 44 ° C. for 5 hours and 45 minutes. The maximum ultimate pressure during this period was 6.0 MPaG.

Polymerization was completed 5 hours and 45 minutes after the temperature rise to 44 ° C was completed. After completion of the polymerization, the obtained copolymer slurry was recovered, dehydrated and washed with water, and further dried at 118 ° C. for 12 hours to obtain a copolymer powder.

Claims

Vinylidene Fluoride units, and
General formula (1): CX 1 X 2 = CX 3 (CF 2 ) n Y
(In the general formula (1), X 1 , X 2 and X 3 are independently H, F, CH 3 , CH 2 F, CHF 2 or CF 3 , but X 1 , X 2 and X 3 Of these, at least one is F, CH 2 F, CHF 2 or CF 3 , at least one is H or CH 3 , n is an integer of 1-6, and Y is H or F. ), Which is a copolymer containing the unit (1) of the monomer.
The content of the monomer (1) unit is 3.0 to 25.0% by mass with respect to all the monomer units.
A copolymer having a melting point of 160 ° C. or higher.
The copolymer according to claim 1, which has a weight average molecular weight of 2000000 or less.
The copolymer according to claim 1 or 2, wherein n is 1 in the general formula (1).
The copolymer according to any one of claims 1 to 3, wherein X 1 and X 2 are independently H or F in the general formula (1).
The monomer (1) is 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene (Z-form) and 1,3,3,3-tetrafluoropropene (E-form). The copolymer according to any one of claims 1 to 4, which is at least one selected from the group consisting of).
A binder containing the copolymer according to any one of claims 1 to 5.
A molded product containing the copolymer according to any one of claims 1 to 5, wherein the molded product is a film, a sheet, a tube, or a melt-spun product.
Vinylidene Fluoride, and
General formula (1): CX 1 X 2 = CX 3 (CF 2 ) n Y
(In general formula (1), X 1 , X 2 and X 3 are independently H, F, CH 3 , CH 2 F, CHF 2 or CF 3 , but X 1 , X 2 and X 3 Of these, at least one is F, CH 2 F, CHF 2 or CF 3 , at least one is H or CH 3 , n is an integer of 1-6, and Y is H or F. ) Is polymerized in a reactor to produce a copolymer containing a vinylidene fluoride unit and a monomer (1) unit.
The content of the monomer (1) unit of the copolymer is 3.0 to 25.0% by mass with respect to all the monomer units.
Before or at the start of the polymerization, 90% by weight or more of the monomer (1) is added to the reactor with respect to the total amount of the monomer (1) to be subjected to the polymerization, and the polymerization is carried out at a polymerization temperature of 0 to 55 ° C. Manufacturing method.
The production method according to claim 8, wherein the polymerization temperature is 30 ° C. or higher.
The production method according to claim 8 or 9, wherein the maximum pressure reached during polymerization is 4.38 MPa or more.
The production method according to any one of claims 8 to 10, wherein suspension polymerization is carried out in the presence of a peroxide polymerization initiator.
The production method according to any one of claims 8 to 11, which polymerizes in the presence of a chain transfer agent.
The production method according to any one of claims 8 to 12, wherein 90% by weight or more of vinylidene fluoride is added to the reactor with respect to the total amount of vinylidene fluoride to be subjected to the polymerization before or at the start of the polymerization.