WO2020017631A1

WO2020017631A1 - Polymer particles and method for producing polymer particles

Info

Publication number: WO2020017631A1
Application number: PCT/JP2019/028433
Authority: WO
Inventors: 桃太郎竹田; 佐竹　庸一; 岩崎　秀治
Original assignee: 株式会社クラレ
Priority date: 2018-07-19
Filing date: 2019-07-19
Publication date: 2020-01-23
Also published as: TW202012468A

Abstract

One aspect of the present invention provides polymer particles which contain a copolymer that comprises a repeating unit represented by formula (1), a repeating unit represented by formula (2) and a repeating unit represented by formula (3) in each molecule, and which have an average primary particle diameter of 0.01-20 μm. In formula (1), R1 represents a hydrogen atom or a methyl group. In formula (2), R2 represents a hydrogen atom or a methyl group. In formula (3), R3 represents a hydrogen atom or a methyl group.

Description

Polymer particles and method for producing polymer particles

<< The present invention relates to a polymer particle and a method for producing the polymer particle.

Secondary batteries used in portable electronic devices such as notebook personal computers and mobile phones, and electric vehicles, etc. must have high energy density, be small, be able to carry large currents, have large capacities, and have high cycle capacity. There is a demand for high performance such as excellent characteristics. As a battery that satisfies such demands, a lithium secondary battery using lithium ions as a charge carrier and utilizing an electrochemical reaction accompanying charge transfer has attracted attention, and its use and development have been promoted. In addition, lithium secondary batteries are charged and discharged by inserting and removing lithium ions from and to electrodes. In order to develop a more suitable lithium secondary battery, it is necessary to have an electrode having such a performance that charging and discharging can be more suitably performed by inserting and removing lithium ions. Therefore, a material for realizing this is required.

有機 In addition, organic compounds having various functions have been developed as organic compounds such as polymers, and for example, materials that can be used for electrodes of lithium secondary batteries as described above have been developed.

材料 As a material that can be used for an electrode of a lithium secondary battery, for example, a material described in Patent Literature 1 is given. As a method for manufacturing a material that can be used for an electrode of a lithium secondary battery, for example, a manufacturing method described in Patent Literature 2 can be used.

Patent Literature 1 discloses a (meth) acrylic acid-based crosslinked copolymer obtained by polymerizing a specific (meth) acrylic acid imino compound and a (meth) acrylic acid ester in the presence of a crosslinking agent, and then nitroxidizing the polymer. Is described. According to Patent Literature 1, a (meth) acrylic acid-based crosslinked copolymer having excellent stability with respect to a solvent and substantially not generating cracks due to drying on the surface of the current collector coated with the solvent can be obtained. Is disclosed.

Patent Document 2 discloses a method for producing a crosslinked poly (meth) acrylic acid nitroxide compound obtained by crosslinking a specific poly (meth) acrylic acid nitroxide compound, wherein the specific (meth) acrylic acid imino compound is used as a crosslinking agent. Polymerization in the presence of a specific poly (meth) acrylic acid imino compound to form a crosslinked (meth) acrylic acid imino compound, and nitroxidation of the crosslinked (meth) acrylic acid imino compound A method for producing a crosslinked poly (meth) acrylic acid nitroxide compound including a nitroxidation step is described. According to Patent Document 2, it is disclosed that a crosslinked poly (meth) acrylic acid nitroxide compound which is excellent in solvent stability and has a high energy density and is used as an electrode material of a large capacity secondary battery can be produced. Have been.

材料 Various materials that can be used for electrodes of lithium secondary batteries have been developed as described above. Further, as described above, the lithium secondary battery is required to have higher performance, and the electrodes provided in the lithium secondary battery are also required to have higher performance. For these reasons, there is a demand for a material capable of realizing higher performance of an electrode provided in a lithium secondary battery.

JP 2008-45096 A International Publication No. 2005/116092

The present invention has been made in view of such circumstances, and when included in an electrode provided in a lithium secondary battery, polymer particles that can produce an electrode suitable for a lithium secondary battery, and An object of the present invention is to provide a method for producing the polymer particles.

The polymer particle according to one aspect of the present invention includes a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3) as a molecule. And an average primary particle diameter of 0.01 to 20 μm.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group.

In the formula (2), R ² represents a hydrogen atom or a methyl group.

In the formula (3), R ³ represents a hydrogen atom or a methyl group.

FIG. 1 is a schematic cross-sectional view illustrating an example of a configuration of a lithium secondary battery including an electrode including a polymer particle according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view illustrating an example of the configuration of an electrode including polymer particles according to one embodiment of the present invention.

According to the study of the present inventors, for example, it has been found that the output of the electrode containing the (meth) acrylic acid-based crosslinked copolymer described in Patent Document 1 does not sufficiently increase.

This means that the (meth) acrylic acid-based cross-linked copolymer described in Patent Document 1 contains the (meth) acrylic acid imino compound and a (meth) acrylic ester similar to the (meth) acrylic acid imino compound. Was presumed to be a copolymer obtained by copolymerizing Specifically, as described above, the (meth) acrylic acid-based crosslinked copolymer polymerizes only the (meth) acrylic acid imino compound by copolymerizing the (meth) acrylic ester. It was found that the hydrophobicity was higher than that of the polymer obtained, and it was presumed that this was due to the increase in the hydrophobicity. As a result, a problem may occur when manufacturing an electrode or the like. For example, when producing an electrode containing the (meth) acrylic acid-based crosslinked copolymer, if the (meth) acrylic acid-based crosslinked copolymer has high hydrophobicity, it becomes difficult to use an aqueous binder. However, a problem based on this may occur. In addition, it was presumed that when the hydrophobicity of the material contained in the electrode was high, the movement of lithium in the electrolytic solution was reduced. For this reason, when the (meth) acrylic acid-based crosslinked polymer was used as an electrode material, the resistance of the electrode was sometimes increased.

According to the study by the present inventors, it has been found that an electrode containing a crosslinked poly (meth) acrylic acid nitroxide compound produced by the production method described in Patent Document 2 does not sufficiently increase output. In the production method described in Patent Document 2, it has been found that even if a crosslinked poly (meth) acrylic acid nitroxide compound can be obtained in the form of particles, the particle diameter, for example, the average primary particle diameter becomes relatively large. This was presumed to be a cause of reducing the output of the electrode obtained using the (meth) acrylic acid-based crosslinked copolymer.

From the above, the electrode containing the (meth) acrylic acid-based crosslinked copolymer described in Patent Document 1 and the electrode containing the crosslinked poly (meth) acrylic acid nitroxide compound produced by the production method described in Patent Document 2 Inferred that the output did not increase sufficiently due to the above. That is, it was presumed that these conventional electrodes did not sufficiently increase the output due to high hydrophobicity and large particles.

In addition, in the copolymer contained in these conventional electrodes, even if the elution to the solvent contained in the electrolyte solution in contact with the electrode could be suppressed, the reason that the output of the electrode did not increase sufficiently was that lithium ions were particles. We speculated that this was due to the lack of a function to stabilize the ions needed to diffuse inside. In addition, as described above, such a copolymer has low compatibility with water, and a hydrophobic binder is used as a substrate for forming an electrode, which is presumed to affect the output of the electrode. There is also a problem that it is difficult to reduce the particle diameter, and a special device is required to reduce the particle diameter.

Therefore, the present inventors first studied the structure of the polymer particles so as to increase the affinity for water (hydrophilicity) and increase the affinity for lithium ions, and further included the structure in the electrode. In some cases, a study was made so that the particle diameter would increase the output of the electrode.

The present inventors have conducted various studies on the above, and as a result, when included in an electrode provided in a lithium secondary battery, provide polymer particles that can produce an electrode suitable for a lithium secondary battery. The above object has been found to be achieved by the present invention described below.

Hereinafter, embodiments according to the present invention will be described, but the present invention is not limited thereto.

The polymer particles according to one embodiment of the present invention include a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a repeating unit represented by the following formula (3) as a molecule. And the copolymer contained therein. Further, the polymer particles have an average primary particle diameter of 0.01 to 20 μm.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group.

In the formula (2), R ² represents a hydrogen atom or a methyl group.

In the formula (3), R ³ represents a hydrogen atom or a methyl group.

電極 When an electrode is manufactured using the polymer particles, an electrode suitable for a lithium secondary battery can be manufactured. That is, the obtained electrode is an electrode containing the polymer particles, and when used as an electrode of a lithium secondary battery, the polymer particles function as a high-output electrode active material, and high-capacity, high-speed charge / discharge is performed. A possible lithium secondary battery can be manufactured. More specifically, a secondary battery having a high actual capacity and a high capacity retention rate after high-speed charge / discharge can be manufactured. Further, the electrode including the polymer particles is an electrode including an electrode active material including the polymer particles, and is an electrode having a high output.

(4) As the lithium secondary battery, for example, a lithium secondary battery as shown in FIG. FIG. 1 is a schematic cross-sectional view illustrating an example of a configuration of a lithium secondary battery including an electrode including polymer particles according to the present embodiment. As shown in FIG. 1, the lithium secondary battery 10 includes a positive electrode 20, a negative electrode 30, and an electrolyte layer 40 interposed between the positive electrode 20 and the negative electrode 30. That is, the positive electrode 20, the electrolyte layer 40, and the negative electrode 30 are stacked in this order. The lithium secondary battery 10 can be discharged, for example, by electrically connecting the positive electrode 20 and the negative electrode 30 via a power meter 50 and the like. The wattmeter 50 can measure the voltage and current of the electricity flowing by this discharge. Then, as the positive electrode 20, an electrode containing the above-described polymer particles can be used.

The electrode containing the polymer particles can be suitably used as an electrode for a lithium secondary battery. For example, as shown in FIG. 2, a current collector 22 and a current collector 22 are provided on the current collector 22. And an electrode 20 including the polymer particles in the electrode layer 21. FIG. 2 is a schematic cross-sectional view illustrating an example of the configuration of the electrode including the polymer particles according to the present embodiment. By providing the electrode 20 in the lithium secondary battery such that the electrode layer 21 is on the electrolyte layer 40 side, a suitable lithium secondary battery is obtained. Specifically, a lithium secondary battery having a high actual capacity and a high capacity retention rate after high-speed discharging and charging can be obtained.

From the above, the polymer particles can be used as an electrode material capable of producing an electrode suitable for a lithium secondary battery, specifically, as an electrode active material. This is thought to be due to the following.

First, the repeating unit represented by the formula (1) has an N-oxy radical in the repeating unit. That is, the copolymer contained in the polymer particles contains the repeating unit having the N-oxy radical. As described above, since the polymer particles include the copolymer having a radical in the molecule, the polymer particles are considered to act as an electrode active material. Further, since this radical is an N-oxy radical in which two quaternary carbons are bonded, the N-oxy radical easily causes an oxidation-reduction reaction, and is thermally and electrochemically stable. Accordingly, the copolymer contained in the polymer particles contains the repeating unit represented by the formula (1) in the molecule together with the repeating unit represented by the formula (2), whereby the polymer It is believed that the particles can act as a high power electrode active material. Further, as described above, such polymer particles have a relatively small average primary particle diameter of 0.01 to 20 μm. From this, it is considered that the polymer particles have a relatively large specific surface area and function as a high-output electrode active material. That is, the polymer particles are considered to be suitable electrode active materials.

The copolymer contained in the polymer particles not only has an N-oxy radical in which two quaternary carbons are bonded as described above, but also has a repeating unit represented by the formula (1), The repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) are contained in a state of being bonded. As described above, since the repeating unit represented by the formula (3) is contained in a state of being bonded to the repeating unit represented by the formula (1), the polymer particles have an affinity for water (hydrophilicity). Sex) is considered to be higher. For this reason, it becomes easy to manufacture an electrode using the polymer particles. Also. Since the copolymer contained in the polymer particles contains the repeating unit represented by the formula (3), when the polymer particles are used as an electrode, the affinity for the electrolytic solution which is a highly polar solvent is obtained. Therefore, it is considered that the movement of lithium ions in the electrode can be made smooth and the diffusion resistance of lithium ions in the electrode can be reduced. From this point, it is considered that a suitable electrode is obtained.

From the above, it is considered that the polymer particles can produce an electrode suitable for a lithium secondary battery. The electrode active material composed of the polymer particles is suitable as an electrode active material for an electrode provided in a lithium secondary battery.

As described above, the copolymer contained in the polymer particles includes a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a compound represented by the formula (3). And each of them is contained in a state of being bonded to the repeating unit represented by Therefore, it is considered that even when the polymer particles are used to form an electrode, the elution of the polymer particles into the solvent contained in the electrolytic solution in contact with the electrode can be suitably suppressed. That is, it is considered that the polymer particles are excellent in anti-elution property (elution resistance) to the solvent.

The polymer particles are suitable as an electrode active material for an electrode provided in a lithium secondary battery. That is, the electrode active material only needs to include the polymer particles, and preferably includes only the polymer particles. The electrode active material composed of the polymer particles is suitable as an electrode active material for an electrode provided in a lithium secondary battery.

The repeating unit represented by the formula (1) is a repeating unit represented by the formula (1), wherein R ¹ is a hydrogen atom or a methyl group. The repeating unit represented by the formula (1) is specifically, a repeating unit represented by the formula (2), for example, 2,2,6,6-tetramethyl-4-piperidinyl acrylate or 2, Examples include a repeating unit obtained by polymerizing 2,6,6-tetramethyl-4-piperidinyl methacrylate into a nitroxide to obtain a repeating unit obtained by polymerizing 2,6,6-tetramethyl-4-piperidinyl methacrylate. When obtaining the repeating unit represented by the formula (1), 2,2,6,6-tetramethyl-4-piperidinyl acrylate and 2,2,6,6-tetramethyl-4-piperidinyl Methacrylate may be used alone, or both may be used in combination.

The repeating unit represented by the formula (2) is a repeating unit represented by the formula (2), wherein R ² is a hydrogen atom or a methyl group. Specific examples of the repeating unit represented by the formula (2) include 2,2,6,6-tetramethyl-4-piperidinyl acrylate and 2,2,6,6-tetramethyl-4-piperidyl acrylate. And repeating units obtained by polymerizing nil methacrylate. Further, the repeating unit represented by the formula (2) is more specifically a repeating unit that is not nitroxidized even when nitroxidation is performed when obtaining the repeating unit represented by the formula (1). Is mentioned. When obtaining the repeating unit represented by the formula (2), the same as in the case of the repeating unit represented by the formula (1), 2,2,6,6-tetramethyl-4-piperidinyl acrylate and 2 , 2,6,6-tetramethyl-4-piperidinyl methacrylate may be used alone, or both may be used in combination.

The repeating unit represented by the formula (3) is a repeating unit in which R ³ is a hydrogen atom or a methyl group. Specific examples of the repeating unit represented by the formula (3) include a repeating unit obtained by polymerizing acrylic acid and methacrylic acid. When obtaining the repeating unit represented by the formula (3), acrylic acid and methacrylic acid may be used alone or in combination.

In the copolymer contained in the polymer particles, the content of the repeating unit [content of (3)] represented by the formula (3) is changed to the content of the repeating unit represented by the formula (1). 0.01 to 5 parts by mass with respect to 100 parts by mass of the total of the amount [content of (1)] and the content of (3) [total content of (1) and (3)]. Is preferably 0.03 to 3 parts by mass, more preferably 0.05 to 1 part by mass. If the content of the above (3) is too small relative to 100 parts by mass of the total content of the above (1) and (3), the effect of the repeating unit represented by the above formula (3) will be sufficiently exhibited. Tend not to be able to. If the content of (3) is too large with respect to 100 parts by mass of the total content of (1) and (3), the effect of having the repeating unit represented by the formula (1) will be lost. There is a tendency not to be able to fully demonstrate. Therefore, when the content is within the above range, the effect of having the repeating unit represented by the formula (1) and the effect of having the repeating unit represented by the formula (3) are more preferably achieved. It is thought that we can show. Specifically, polymer particles capable of producing an electrode capable of producing a high-output lithium secondary battery can be obtained.

Here, as a method for measuring the content of (1), a chemical titration method according to an oxidation-reduction reaction and the like can be mentioned. For example, after swelling with an appropriate solvent, an aqueous solution of potassium iodide is added, and the released iodine can be quantified by back titration with an aqueous solution of sodium thiosulfate.

として As a method for measuring the content of (3), a chemical titration method according to a neutralization reaction and the like can be mentioned. For example, the amount can be determined by swelling with an appropriate solvent and then titrating with a potassium hydroxide solution.

In the copolymer contained in the polymer particles, the content of the repeating unit represented by the formula (2) [content of (2)] is equal to the content of (1) and the content of (2). ) Is preferably 0.01 to 10 parts by mass, and more preferably 0.01 to 5 parts by mass with respect to 100 parts by mass with respect to the total of [1] and (2). Is more preferable, and the content is more preferably 0.01 to 2 parts by mass. If the content of the above (2) is too large relative to 100 parts by mass of the total content of the above (1) and (2), the effect of having the repeating unit represented by the above formula (1) will be sufficiently improved. There is a tendency not to show. Further, the content of the above (2) may be small, but in fact, it is contained above the lower limit of the above range. Therefore, it is considered that when the content is within the above range, the effect of having the repeating unit represented by the formula (1) can be more suitably exerted. Specifically, polymer particles capable of producing an electrode capable of producing a high-output lithium secondary battery can be obtained.

As the method for measuring the content of (1), for example, a method of quantifying nitroxide free radicals using a chemical titration method based on a redox reaction (redox titration method), infrared spectroscopy (IR ), A method of quantifying the imino group remaining in the reaction product using a method, and a method of calculating the spin concentration in the reaction product using an electron spin resonance (ESR method). .

として As a method for measuring the content of (2), a chemical titration method according to a neutralization reaction and the like can be mentioned. For example, the amount can be determined by swelling with an appropriate solvent and then titrating with a strong acid such as hydrochloric acid.

The polymer particles have an average primary particle size (average particle size of primary particles) of 0.01 to 20 μm, preferably 0.05 to 10 μm, and more preferably 0.1 to 5 μm. . It is considered that the smaller the primary particles of the polymer particles, the more suitable the electrode active material. If the primary particles of the polymer particles are too large, the polymer particles tend not to work favorably as an electrode active material. It is considered that this is because the polymer particles have few contacts with the conductive material and the current collecting property is reduced. On the other hand, there is a limit in reducing the size of the polymer particles. This is considered to be because if the primary particles of the polymer particles are too small, purification operations such as recovery during the production become complicated. For this reason, the primary particle size of the polymer particles is limited to an average particle size of about 0.01 μm. Therefore, the average primary particle diameter of the polymer particles is in the above range. Polymer particles having such a size are considered to be suitable electrode active materials, and polymer particles capable of producing an electrode suitable for a lithium secondary battery can be obtained. Specifically, polymer particles capable of producing an electrode capable of producing a high-output lithium secondary battery can be obtained.

The average primary particle diameter here is, for example, a volume-based average particle diameter (MV: Mean Volume Diameter) of the primary particles. Specific examples include a volume average particle diameter (MV) determined from a particle size distribution measured by a general laser diffraction / scattering method or an image analysis method of an electron microscope image.

共 The copolymer contained in the polymer particles is preferably crosslinked. That is, in the copolymer contained in the polymer particles, it is preferable that the polymer chains containing the repeating units are crosslinked. The crosslinking is not particularly limited as long as the polymer chains containing the repeating unit are crosslinked. For example, the copolymer preferably contains a repeating unit represented by the following formula (4). The copolymer is preferably crosslinked by including such a repeating unit.

In the formula (4), R ⁴ and R ⁵ each independently represent a hydrogen atom or a methyl group, and Z represents an ethylene group, a propylene group, a butylene group, or a —C ₂ H ₄ OC ₂ H ₄ — group. Is shown.

In the repeating unit represented by the formula (4), R ⁴ and R ⁵ are each independently a hydrogen atom or a methyl group, and Z is an ethylene group, a propylene group, a butylene group, or —C ₂ It is a repeating unit that is an H ₄ OC ₂ H ₄ — group. Specific examples of the repeating unit represented by the formula (4) include ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, diethylene glycol dimethacrylate, 1,3-propanediol diacrylate, and 1,3-propane. Diol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, and 1,4-butanediol dimethacrylate are represented by the formulas (1) to (3). And the repeating unit obtained by polymerization at the time of polymerization for producing the repeating unit represented by the formula (1). Since the copolymer is crosslinked, the polymer particles are considered to be more excellent in anti-elution property (elution resistance) to a solvent. That is, it is considered that even when the polymer particles are used as an electrode, the elution of the polymer particles into the solvent contained in the electrolytic solution that comes into contact with the electrode can be more suitably suppressed. In addition, since it is only cross-linked, it is considered that the effects of the cross-linking having the repeating units represented by the formulas (1) and (3) are not likely to be inhibited. Therefore, it is considered that a polymer particle having more excellent elution resistance can be obtained while exhibiting the respective effects sufficiently by having the repeating units represented by the formulas (1) and (3).

As described above, the copolymer preferably contains the repeating unit represented by the formula (4). When the copolymer contains the repeating unit represented by the formula (4), the copolymer has a content of the repeating unit represented by the formula (4) [content of (4)], It is preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the total of the content of 1) and the content of (3) [total content of (1) and (3)], and 0 to 5 parts by mass. The amount is more preferably from 0.2 to 4.5 parts by mass, and even more preferably from 0.5 to 4 parts by mass. When the content of (4) is too small relative to 100 parts by mass of the total content of (1) and (3), the effect of crosslinking by the repeating unit represented by the formula (4) is sufficiently exhibited. Tend not to be able to. If the content of (4) is too large relative to 100 parts by mass of the total content of (1) and (3), the repeating unit represented by the formula (1) and the formula (3) The effect of having the repeating unit represented by the formula (1) tends to be insufficient. Therefore, when the content is within the above range, the effect of having the repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) is sufficiently exhibited, and the elution resistance is improved. It is considered that it can be suitably used.

The content of the above (4) is determined by determining the content of other repeating units (the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the formula (2) in the copolymer. Each content of the repeating unit represented by 3) is measured by a chemical titration method or the like, and can be calculated from each content of the other repeating units. Specifically, it can be calculated from the difference between the amount of the copolymer and the total amount of each content of the other repeating units.

In the copolymer, a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), a repeating unit represented by the formula (3), and a compound represented by the formula (4) The presence of each of the repeating units represented by the formula (1) indicates that the copolymer, the copolymer obtained by reducing the copolymer, and the copolymer before nitroxidation are subjected to ¹ H-NMR or infrared spectroscopy (IR). And the like, or the copolymer can be measured by the above-mentioned chemical titration method, or can be confirmed by combining these measurements.

The polymer particles only need to contain the copolymer, and may contain other components. When an electrode is manufactured using polymer particles, an electrode material containing the polymer particles is used. The electrode material only needs to contain the polymer particles, and may contain other components. These other components include, for example, an auxiliary conductive material and an ion conductive auxiliary material. Examples of the auxiliary conductive material include carbonaceous fine particles and a conductive polymer. Examples of the carbonaceous fine particles include fine particles such as graphite, carbon black, and acetylene black. Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, polyacetylene, and polyacene. In addition, examples of the ion conduction auxiliary material include a polymer gel electrolyte and a polymer solid electrolyte.

製造 The method for producing the polymer particles is not particularly limited as long as the polymer particles can be produced. As a method for producing the polymer particles, specifically, a monomer composition containing an imino compound represented by the following formula (5) and (meth) acrylic acid represented by the following formula (6) is used. A production method comprising a first step of polymerizing (polymerization step) and a second step of nitroxidation of the polymer obtained in the first step (nitroxidation step) is exemplified. Here, (meth) acrylic acid refers to acrylic acid or methacrylic acid.

In the formula (5), R ⁶ represents a hydrogen atom or a methyl group.

In the formula (6), R ⁷ represents a hydrogen atom or a methyl group.

According to the production method as described above, first, in the first step, a monomer containing the imino compound represented by the formula (5) and the (meth) acrylic acid represented by the formula (6) By polymerizing the composition, a copolymer containing the repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) in a molecule can be obtained. In the second step, the copolymer (the polymer obtained in the first step) is nitroxidized, so that the imino group contained in the copolymer is nitroxidized. A part of the repeating unit represented is a repeating unit represented by the formula (1). From this, a copolymer containing the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the repeating unit represented by the formula (3) in a molecule is can get.

The polymer obtained in the first step is obtained in the form of particles, and the particles containing the polymer are in the form of a particulate polymer obtained by polymerizing only the imino compound represented by the formula (5). Since particles smaller than the coalesced particles are obtained, the particles containing the copolymer obtained in the second step are also reduced. From this, a copolymer containing the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the repeating unit represented by the formula (3) in a molecule is used. Thus, polymer particles having an average primary particle diameter of 0.01 to 20 μm are obtained. Therefore, the manufacturing method can suitably manufacture polymer particles that become electrodes suitable for a lithium secondary battery when included in an electrode provided in the lithium secondary battery.

Examples of the (meth) acrylic acid imino compound represented by the formula (5) include, for example, 2,2,6,6-tetramethyl-4-piperidinyl acrylate and 2,2,6,6-tetra Methyl-4-piperidinyl methacrylate and the like. As the (meth) acrylic acid imino compound, these may be used alone, or two or more kinds may be used in combination.

前記 The (meth) acrylic acid represented by the formula (6) is acrylic acid or methacrylic acid. As the (meth) acrylic acid, these may be used alone or in combination of two types.

The method of polymerizing the (meth) acrylic acid imino compound represented by the formula (5) and the (meth) acrylic acid represented by the formula (6) (the method of polymerization in the first step) includes: For example, a method of polymerizing by a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, and the like can be given. In addition, as the polymerization step in the first step, it is preferable to carry out the polymerization in the presence of a crosslinking agent, and specifically, a suspension polymerization method or an emulsion polymerization method is preferable. By doing so, the above-mentioned polymer particles can be suitably produced. Therefore, it is possible to produce polymer particles that can produce a more suitable electrode with a lithium secondary battery.

The mixing ratio of the (meth) methacrylic acid is preferably from 0.0003 to 0.25 mol, more preferably from 0.0006 to 0.09 mol, per 1 mol of the (meth) acrylic acid imino compound. Is more preferably 0.0008 to 0.028 mol. That is, it is particularly preferable to use 0.08 to 2.8 mol parts of the (meth) acrylic acid with respect to 100 mol parts of the (meth) acrylic acid imino compound. When the (meth) acrylic acid is within the above range, a suitable polymer particle can be produced.

In the monomer composition, not only the (meth) acrylic acid imino compound represented by the formula (5) and the (meth) acrylic acid represented by the formula (6), but also another monomer May contain body. The monomer composition preferably contains a crosslinking agent as another monomer.

The crosslinking agent is not particularly limited as long as it is a compound having a plurality of polymerizable unsaturated groups in the molecule. Examples of the crosslinking agent include (meth) acrylic acid-based polyfunctional compounds, allyl ether-based polyfunctional compounds, and vinyl-based polyfunctional compounds. Examples of the (meth) acrylic acid-based polyfunctional compound include a crosslinking agent represented by the following formula (7). Specifically, ethylene glycol diacrylate, ethylene glycol dimethacrylate, diethylene glycol diacrylate, Diethylene glycol dimethacrylate, 1,3-propanediol diacrylate, 1,3-propanediol dimethacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, and 1,4-butanediol dimethacrylate and the like. Examples of the allyl ether polyfunctional compound include, for example, diethylene glycol diallyl ether and dibutylene glycol diallyl ether. Examples of the vinyl polyfunctional compound include, for example, divinylbenzene. Among these, from the viewpoint of having high polymerization reactivity, the (meth) acrylic acid-based polyfunctional compound is preferable, and a crosslinking agent represented by the following formula (7) is more preferable, and ethylene glycol di (meth) acrylate and diethylene glycol (Meth) acrylate and 1,4-butanediol di (meth) acrylate are more preferred. As the crosslinking agent, the compounds exemplified above may be used alone, or two or more of them may be used in combination.

In the formula (7), R ⁸ and R ⁹ each independently represent a hydrogen atom or a methyl group, and Z represents an ethylene group, a propylene group, a butylene group, or a —C ₂ H ₄ OC ₂ H ₄ — group. Is shown.

In the first step, when a composition containing the crosslinking agent represented by the formula (7) is polymerized as the monomer composition, the polymer particles are represented by the formula (4) among the polymer particles. Polymer particles containing a copolymer further containing a repeating unit in the molecule can be suitably produced.

The mixing ratio of the crosslinking agent is preferably 0.00001 to 0.25 with respect to 1 mol of the (meth) acrylic acid imino compound in order to sufficiently exhibit the effect of crosslinking by the crosslinking agent when the crosslinking agent is included. Mole, more preferably 0.00005 to 0.1 mole, even more preferably 0.0001 to 0.05 mole.

As the suspension polymerization method, for example, the (meth) acrylic acid imino compound, the (meth) acrylic acid, the cross-linking are performed by using a reactor equipped with a stirrer, a thermometer, a nitrogen gas introducing pipe, and a cooling pipe. After mixing a predetermined amount of an agent and an oil-soluble radical polymerization initiator with an inert hydrocarbon-based solvent, respectively, and a surfactant, and mixing and dispersing the mixture with water that is inert to the reaction, nitrogen gas is used. And heating under stirring.

として The oil-soluble radical polymerization initiator is not particularly limited. Examples of the oil-soluble radical polymerization initiator include a peroxide-based polymerization initiator, an azo-based polymerization initiator, and a redox-based polymerization initiator. Examples of the peroxide-based polymerization initiator include benzoyl peroxide, tert-butyl peroxide, diisopropylperoxydicarbonate, and dicyclohexylperoxydicarbonate. Examples of the azo polymerization initiator include α, α′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, and dimethyl-2,2′-azobis Isobutyrate and the like. Examples of the redox polymerization initiator include benzoyl peroxide / dimethylaniline, di-tert-butyl peroxide / dimethylaniline, and lauroyl peroxide / dimethylaniline. Among these oil-soluble radical polymerization initiators, azo-based polymerization initiators such as α, α′-azobisisobutyronitrile, which are inexpensive and easy to handle, are suitably used.

The amount of the oil-soluble radical polymerization initiator to be used varies depending on the type of the oil-soluble radical polymerization initiator to be used and the reaction temperature, but is usually 0.005 to 5 based on 100 parts by mass of the (meth) acrylic acid imino compound. It is preferably in parts by mass.

The inert hydrocarbon solvent is not particularly limited. Examples of the inert hydrocarbon solvents include aromatic hydrocarbon solvents, acyclic saturated hydrocarbon solvents, cyclic saturated hydrocarbon solvents, and halogenated hydrocarbon solvents. Examples of the aromatic hydrocarbon-based solvent include benzene, toluene, xylene, and the like. Examples of the acyclic saturated hydrocarbon solvent include n-hexane, n-heptane, and ligroin. Examples of the cyclic saturated hydrocarbon solvent include cyclopentane, methylcyclopentane, cyclohexane, and methylcyclohexane. Examples of the halogenated hydrocarbon solvent include dichloromethane, chloroform, dichloroethane, and the like. As the inert hydrocarbon-based solvent, among them, an aromatic hydrocarbon-based solvent, and an acyclic solvent are commercially available, from the viewpoint of inexpensiveness and stable quality of the obtained polymerization reaction product. Saturated hydrocarbon solvents are preferred, and among them, toluene and n-hexane are suitably used. As the inert hydrocarbon solvent, the solvents exemplified above may be used alone, or two or more of them may be used in combination.

The amount of the inert hydrocarbon-based solvent used is from the viewpoint of dissolving the (meth) acrylic acid imino compound sufficiently to allow the polymerization reaction to proceed smoothly, and from the viewpoint of obtaining an effect commensurate with the used amount. ) The amount is preferably from 50 to 300 parts by mass, more preferably from 100 to 200 parts by mass, per 100 parts by mass of the imino acrylate compound.

として As the surfactant, any of anionic surfactant, cationic surfactant, nonionic surfactant, and amphoteric surfactant can be used.

Examples of the anionic surfactant include fatty acid sodium, fatty acid ammonium, fatty acid potassium, sodium alkyl sulfate, ammonium alkyl sulfate, sodium alkylbenzene sulfonate, sodium alkane sulfonate, ammonium alkane sulfonate, sodium alkyl phosphate, and acyloylmethyl. Taurate, sodium N-methyl-N-acylamidopropionate, sodium monoalkylbiphenyl ether disulfonate, sodium naphthalenesulfonate-formalin condensate, sodium acylglutamate, polyoxyethylene alkylphenyl ether alkylbenzenesulfonate sodium, polyoxyethylene Sodium alkyl ether sulfate, polyoxyethylene alkyl ether methyl carboxy Sodium, and sodium polyoxyethylene alkyl ether ethanesulfonic acid and the like.

Examples of the cationic surfactant include monoalkyltrimethylammonium methosulfate, cationized cellulose, alkyltrimethylammonium chloride, distearyldimethylammonium chloride, dialkyldimethylammonium chloride, dialkyldimethylbenzylammonium chloride, and alkylpyridinium chloride. No.

Examples of the nonionic surfactant include fatty acid monoglyceride, sorbitan fatty acid partial ester, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid monoglyceride, polyoxyethylene sorbitol fatty acid partial ester, polyoxyethylene sorbitan Fatty acid partial ester, polyoxyethylene lanolin alcohol ether, polyethylene glycol fatty acid monoester, polyethylene glycol fatty acid diester, polyoxyethylene fatty acid amine, polyglycerin fatty acid partial ester, bis (2-hydroxyethyl) alkylamine, alkyldimethylamine oxide, fatty acid Alkylolamide, ω-methoxypolyoxyethylene-α-alkyl ether, Examples include polyoxyethylene polyoxypropylene block copolymer, polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene acetylene glycol, sugar fatty acid partial ester, polyvinyl alcohol, and partially saponified polyvinyl alcohol.

Examples of the amphoteric surfactant include N-acylamidopropyl-N, N-dimethylammoniobetaine, N-acylamidopropyl-N ′, N′-dimethyl-N′-β-hydroxypropylammoniosulfobetaine. , N-acylamidoethyl-N'-hydroxyethyl-N'-carboxymethylammoniobetaine, N-alkyl-N-dimethyl-N-carboxymethylammoniobetaine, alkyldiaminoethylglycine, and acylated polypeptides. No.

As the surfactant, among the above-mentioned surfactants, from the viewpoint of being easily available industrially, inexpensive, and stabilizing the quality of the obtained polymerization reaction product, sodium alkylbenzene sulfonate, polyoxyethylene alkylphenyl Sodium ether alkylbenzene sulfonate, polyvinyl alcohol, and partially saponified polyvinyl alcohol are preferably used. Also, among the sodium alkylbenzenesulfonates, sodium dodecylbenzenesulfonate is preferable, and among the sodium polyoxyethylenealkylphenyletheralkylbenzenesulfonates, sodium polyoxyethylenenonylphenyletherdodecylbenzenesulfonate is preferable.

The amount of the surfactant to be used is preferably 0.05 to 10 parts by mass with respect to 100 parts by mass of water to be added, from the viewpoint of promoting the reaction smoothly and obtaining an effect commensurate with the amount used. More preferably, it is 0.1 to 5 parts by mass.

The amount of the water to be used is preferably 200 to 3000 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid imino compound from the viewpoint of sufficiently removing the heat of polymerization and facilitating the control of the polymerization temperature. More preferably, it is 300 to 2,000 parts by mass.

The reaction conditions in the suspension polymerization method are not particularly limited as long as the (meth) acrylic acid imino compound and the (meth) acrylic acid can be polymerized. Specifically, the reaction temperature is preferably 30 to 100 ° C, more preferably 40 to 80 ° C. The reaction time varies depending on the reaction temperature and the like and cannot be unconditionally determined, but is usually preferably 0.5 to 10 hours.

重合 Since the polymerization reaction product obtained by the above suspension polymerization method exists in the form of particles in the reaction solvent, it can be isolated by filtering this reaction solution. Further, it can be purified by removing unreacted substances and the like using water, methanol, hexane and the like, washing and drying. In this way, polymer particles before nitroxidation are obtained. This polymer particle is a polymer particle containing the repeating unit represented by the formula (2).

乳化 Examples of the emulsion polymerization method include a general emulsion polymerization method. As the emulsion polymerization method, for example, a (meth) acrylic acid imino compound, the (meth) acrylic acid, the cross-linking agent are used by using a reactor equipped with a stirrer, a thermometer, a nitrogen gas inlet pipe, and a cooling pipe. And, after mixing and dispersing a predetermined amount of each of the surfactants in water as an inert solvent, deoxygenate with nitrogen gas, add a water-soluble radical polymerization initiator, and heat under stirring. Method. In the above method, the (meth) acrylic acid imino compound, the (meth) acrylic acid, and a mixture obtained by previously mixing the crosslinking agent (if necessary, an inert hydrocarbon solvent or a hydrophilic solvent such as methanol (aqueous solution) ) May be added to water containing the surfactant and the water-soluble radical polymerization initiator, and heated under stirring. Thus, the aqueous solvent solution containing the monomer composition containing the (meth) acrylic acid imino compound, the (meth) acrylic acid, and the crosslinking agent is converted into an aqueous solution containing a surfactant and a polymerization initiator. By the addition, the monomer composition can be suitably polymerized, and the polymer particles can be more suitably produced. The water-soluble solvent is not particularly limited as long as it is water-soluble and can dissolve the monomer composition. Examples of the water-soluble solvent include methanol, ethanol, isopropyl alcohol, diglyme, tetrahydrofuran, acetone, acetonitrile, dimethylformamide, and dimethyl sulfoxide.

として The water-soluble radical polymerization initiator is not particularly limited. Examples of the water-soluble radical polymerization initiator include a peroxide-based polymerization initiator and a redox-based polymerization initiator. Examples of the peroxide-based polymerization initiator include ammonium persulfate, sodium persulfate, and potassium persulfate. Examples of the redox polymerization initiator include, for example, ammonium ferrous sulfate / ammonium persulfate, ethanolamine / potassium persulfate, and the like. Among these, a peroxide polymerization initiator such as potassium persulfate, which is inexpensive and easy to handle, is preferably used as the water-soluble radical polymerization initiator. As the water-soluble radical polymerization initiator, the initiators exemplified above may be used alone, or two or more of them may be used in combination.

In the emulsion polymerization method, the type and amount of the surfactant, the amount of the polymerization initiator used, the amount of water used as the inert solvent, the reaction temperature, and the reaction time are the same as those in the suspension polymerization method. Can be applied.

In the emulsion polymerization method, in order to dissolve the (meth) acrylic acid imino compound, an inert hydrocarbon solvent similar to that used in the suspension polymerization method, or a hydrophilic solvent such as methanol may be appropriately added. Further, if necessary, an additive such as a chain transfer agent such as isopropyl alcohol or a polymerization terminator may be appropriately added.

重合 The polymerization reaction product obtained by the emulsion polymerization method can be isolated, for example, by mixing the reaction solution with a large amount of cold water, precipitating the polymerization reaction product, and then filtering. Further, it can be purified by removing unreacted substances and the like using water, hexane, methanol and the like, washing and drying. In this way, polymer particles before nitroxidation are obtained. This polymer particle is a polymer particle containing the repeating unit represented by the formula (2).

分散 As the dispersion polymerization method, a general dispersion polymerization method and the like can be mentioned. As the dispersion polymerization method, for example, a (meth) acrylic acid imino compound, the (meth) acrylic acid, the cross-linking agent is used by using a reactor equipped with a stirrer, a thermometer, a nitrogen gas introducing pipe, and a cooling pipe. And a dispersion medium mixed and dispersed in an inert solvent, deoxygenated with nitrogen gas, a radical polymerization initiator is added, and the mixture is heated under stirring.

ラジカル The radical polymerization initiator used in the dispersion polymerization method is not particularly limited, and for example, those which can be used in the suspension polymerization method or the emulsion polymerization method can be used.

使用 In the dispersion polymerization method, the same amount as that in the suspension polymerization method can be applied to the amount of the polymerization initiator, the reaction temperature, and the reaction time.

The inert solvent used in the dispersion polymerization method is not particularly limited as long as the (meth) acrylic acid imino compound, the (meth) acrylic acid, the crosslinking agent, and the dispersion medium can be sufficiently dissolved. Not done. Examples of the inert solvent include aromatic hydrocarbon solvents such as benzene, toluene and xylene; acyclic saturated hydrocarbon solvents such as n-hexane, n-heptane and ligroin; cyclopentane, methylcyclopentane, Cyclic saturated hydrocarbon solvents such as cyclohexane and methylcyclohexane; halogenated hydrocarbon solvents such as dichloromethane, chloroform and dichloroethane; methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl Alcohols such as alcohol, iso-butyl alcohol and tert-butyl alcohol; and water. As the inert solvent, among the solvents exemplified above, alcohols are preferred from the viewpoint of industrial availability, low cost, high solubility of the (meth) acrylic acid imino compound, and methanol. More preferred. As the inert solvent, the solvents exemplified above may be used alone, or two or more of them may be used in combination.

The dispersion medium used in the dispersion polymerization method is not particularly limited, and examples thereof include polystyrene, polymethyl methacrylate, polyvinyl butadiene, poly (N-vinylpyrrolidone), polyacrylic acid, polymethacrylic acid, poly (dimethylsiloxane), Examples thereof include polyisobutylene, polyethylene glycol, polypropylene glycol, poly (ethyl vinyl ether), polyvinyl alcohol, partially saponified polyvinyl alcohol, polyvinyl acetate, and polyvinyl butyral. As the dispersant, among the compounds exemplified above, poly (N-vinylpyrrolidone), polyvinyl alcohol, and the like are commercially available, inexpensive, and easily washed and removed from the polymerization reaction product. And partially saponified polyvinyl alcohol are preferred, and polyvinyl alcohol is more preferred. Further, as the dispersion medium, the above-described dispersion medium may be used alone, or two or more kinds may be used in combination.

使用 The amount of the dispersion medium used in the dispersion polymerization method is not particularly limited as long as the polymerization reaction product fine particles can be dispersed in the reaction solvent. The amount of the dispersion medium used is, for example, from the viewpoint of dispersing the fine particles of the polymerization reaction product in the reaction solvent and obtaining an effect commensurate with the amount used, to 100 parts by mass of the (meth) acrylic acid imino compound. On the other hand, it is preferably 1 to 100 parts by mass, more preferably 5 to 40 parts by mass.

重合 The polymerization reaction product obtained by the dispersion polymerization method can be isolated, for example, by mixing the reaction solution with a large amount of cold water, precipitating the polymerization reaction product, and then filtering. Further, it can be purified by removing unreacted substances and the like using water, hexane, methanol and the like, washing and drying.

The second step is not particularly limited as long as the repeating unit represented by the formula (2) can be converted into a repeating unit represented by the formula (1) by nitroxidation. The nitroxidation in the second step includes, for example, nitroxidation of 2,2,6,6-tetramethyl-4-piperidine and 2,2,6,6-tetramethyl-4-piperidinyl (meth) acrylate. A well-known method that can be used is exemplified. Examples of the nitroxidation include a known method for producing a compound having a corresponding nitroxide free radical (nitroxide radical group) by oxidizing a secondary amine having steric hindrance using an oxidizing agent. be able to. Examples of the nitroxidation include a method in which a polymer particle containing the repeating unit represented by the formula (2) is mixed with an inert solvent, and the mixture is reacted with stirring while adding an oxidizing agent. Can be By such a method, the polymer particles containing the repeating unit represented by the formula (2) (the polymer particles before nitroxidation) are converted into the polymer containing the repeating unit represented by the formula (1). Into particles (polymer particles after nitroxidation).

Examples of the inert solvent include halogenated hydrocarbons, aliphatic nitriles, aromatic nitriles, alcohols, aromatic hydrocarbons, and water. Examples of the halogenated hydrocarbons include dichloromethane, chloroform, dichloroethane, and the like. Examples of the aliphatic nitriles include acetonitrile, propionitrile, and butyronitrile. Examples of the aromatic nitriles include benzonitrile and tolunitrile. Examples of the alcohol include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butyl alcohol, sec-butyl alcohol, iso-butyl alcohol, tert-butyl alcohol and the like. Examples of the aromatic hydrocarbons include benzene, toluene, and xylene. As the inert solvent, among these, halogenated hydrocarbons such as dichloromethane, chloroform and dichloroethane, and alcohols such as methanol, ethanol and tert-butyl alcohol are preferably used. As the inert solvent, the solvents exemplified above may be used alone, or two or more of them may be used in combination. In addition, in the nitroxidation reaction, the polymer particles before the nitroxidation need not necessarily be dissolved in an inert solvent, and the nitroxidation reaction proceeds easily, for example, even in a swollen state.

The amount of the inert solvent to be used is from 50 to 5,000 parts by mass with respect to 100 parts by mass of the polymer particles before nitroxidation, from the viewpoint of smoothly proceeding the reaction and obtaining an effect commensurate with the amount used. And more preferably 100 to 3000 parts by mass.

The oxidizing agent is not particularly limited as long as it is an oxidizing agent capable of nitroxidation. Examples of the oxidizing agent include peroxides such as hydrogen peroxide, formic acid, peracetic acid, perbenzoic acid, and perphthalic acid, halides thereof, and air.

The oxidizing agent is used in an amount of 1 mol of the (meth) acrylic acid imino compound used in the production of the polymer particles before nitroxidation, from the viewpoint of smoothly proceeding the reaction and obtaining an effect commensurate with the amount used. Is preferably from 1 to 100 mol, more preferably from 1.5 to 50 mol, even more preferably from 2 to 30 mol.

触媒 In the nitroxidation step, a catalyst can be used as necessary in the reaction. The catalyst is not particularly limited, and a catalyst used in a usual nitroxidation reaction can be used. Examples of the catalyst include compounds containing a metal element selected from Group 6 of the Periodic Table of the Group 18 elements, such as tungsten and molybdenum. More specifically, a tungsten compound, a molybdenum compound, and the like can be given. Examples of the tungsten compound include tungstic acid, phosphotungstic acid, paratungstic acid, alkali metal salts (such as sodium salt and potassium salt) and ammonium salts thereof, tungsten oxide, and tungsten carbonyl. Examples of the molybdenum compound include molybdic acid, phosphomolybdic acid, paramolybdic acid, and alkali metal salts (such as sodium salt and potassium salt) and ammonium salts thereof. As the catalyst, among these, specifically, ammonium paratungstate, sodium tungstate, phosphotungstic acid, sodium molybdate, molybdenum trioxide, molybdenum hexacarbonyl and the like are preferably used.

The amount of the catalyst used is 0.001 to 20 parts by mass based on 100 parts by mass of the polymer particles before nitroxidation from the viewpoint of smoothly proceeding the reaction and obtaining an effect commensurate with the amount used. And more preferably 0.01 to 10 parts by mass.

Since the nitroxidation in the second step can be easily performed in a high yield as an operation, first, after mixing the polymer particles before the nitroxidation, the inert solvent, and the catalyst as necessary, It is preferable to carry out the reaction while adding the oxidizing agent. In this nitroxidation, water or the like may be added to dissolve the catalyst, and if necessary, a phase transfer catalyst such as a quaternary ammonium salt or a phosphonium salt may be appropriately added. As the phase transfer catalyst, specifically, tetrabutylammonium bromide, tetrabutylammonium chloride, trioctylmethylammonium chloride, phenyltrimethylammonium chloride, cetylpyridinium bromide, tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, and tributyldodecyl And phosphonium bromide.

反応 The reaction conditions for the nitroxidation are not particularly limited as long as the nitroxidation occurs. Specifically, the reaction temperature is preferably from 0 to 100 ° C, more preferably from 20 to 80 ° C. The time for the reaction while the oxidizing agent is added is not particularly limited, but is usually 1 to 10 hours, preferably 3 to 6 hours. Further, usually, after the addition of the oxidizing agent is completed, the reaction is completed by maintaining the temperature. After completion of the addition of the oxidizing agent, the time for completing the reaction while maintaining the temperature is preferably 2 to 24 hours, more preferably 4 to 16 hours.

ニトロ The polymer particles obtained by the above reaction after nitroxidation can be isolated from the reaction solution by a combination of filtration, drying and the like. The reaction product can be isolated, for example, by mixing the reaction solution with a large amount of cold water, precipitating the polymerization reaction product, and then filtering. Further, it can be purified by removing unreacted substances and the like using water, hexane, methanol and the like, washing and drying.

According to the method for producing polymer particles described above, polymer particles capable of producing an electrode suitable for a lithium secondary battery can be suitably produced. Specifically, according to such a production method, the polymer particles according to the embodiment of the present invention can be produced. That is, the copolymer contains a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a repeating unit represented by the formula (3) in a molecule, Polymer particles having an average primary particle size of 0.01 to 20 μm can be produced.

重合 As described above, the polymer particles according to this embodiment are preferably used for manufacturing an electrode for a lithium secondary battery. That is, an electrode for a lithium secondary battery according to another embodiment of the present invention includes a current collector and an electrode layer provided on the current collector, and the electrode layer includes the polymer particles. . Specifically, in the electrode 20 shown in FIG. 2, the electrode layer 21 includes an electrode containing the polymer particles. In addition, the electrode layer 21 only needs to include the polymer particles, and may include other components. Further, the electrode layer 21 may be a layer made of the polymer particles.

The current collector is not particularly limited as long as it is used as a current collector. Examples of the current collector include a metal foil, a metal flat plate, a metal mesh, and a carbon rod. Examples of the metal foil, the metal plate, and the metal mesh include those containing nickel, aluminum, copper, gold, silver, an aluminum alloy, stainless steel, and the like.

製造 The method for manufacturing the electrode is not particularly limited as long as the electrode can be manufactured. Examples of the method for producing the electrode include a method including a coating step of forming the polymer particles into a coating, and a coating step of coating the coating on a current collector.

塗料 The coating process and the coating process are not particularly limited, and can be performed using a known method or apparatus.

塗料 The coating process includes, for example, a method of mixing a binder with the polymer particles and adding a solvent to form a slurry. Examples of the binder include polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, styrene-butadiene copolymer rubber, polypropylene, polyethylene, polyimide, and various polyurethanes. Resin binder. Examples of the solvent include dimethylformamide and N-methylpyrrolidone.

The application step is, for example, a step of applying the paint (slurry) obtained in the paint-forming step to the surface of the current collector. Specifically, the coating material (slurry) obtained in the coating process is dropped on the surface of the current collector, developed with a wire bar so as to have a uniform thickness, and then dried to remove the solvent. And the like.

膜厚 The thickness of the coating film obtained by the coating step is preferably from 10 to 1000 μm, more preferably from 50 to 300 μm.

電極 Such an electrode is an electrode more suitable for a lithium secondary battery. That is, by providing the electrode layer containing the polymer particles, an electrode more suitable for a lithium secondary battery can be obtained. Specifically, by using the electrode, a lithium secondary battery having a high actual capacity, a capacity deriving efficiency, and a high-speed discharge / charge capacity retention rate can be obtained.

As described above, the electrode according to the present embodiment is preferably used as an electrode for a lithium secondary battery. That is, a lithium secondary battery according to another embodiment of the present invention includes the electrode. Specifically, in the lithium secondary battery 10 shown in FIG. 1, as the positive electrode 20, a battery or the like including the electrode is used. Such a lithium secondary battery is a more suitable lithium secondary battery. Specifically, it is possible to obtain a lithium secondary battery having a high actual capacity, capacity display efficiency, and high retention rate of high-speed discharge / charge capacity.

As described above, this specification discloses various aspects of the technology, and the main technologies are summarized below.

In the formula (1), R ¹ represents a hydrogen atom or a methyl group.

In the formula (2), R ² represents a hydrogen atom or a methyl group.

In the formula (3), R ³ represents a hydrogen atom or a methyl group.

According to such a configuration, it is possible to provide polymer particles capable of producing an electrode suitable for a lithium secondary battery when included in an electrode provided in the lithium secondary battery. That is, when an electrode is manufactured using the polymer particles, an electrode suitable as an electrode of a lithium secondary battery can be obtained. Specifically, when the obtained electrode is used as an electrode of a lithium secondary battery, the polymer particles act as a high-output electrode active material to produce a lithium secondary battery capable of high capacity and high speed charge / discharge. can do. More specifically, it is possible to manufacture a lithium secondary battery having a high actual capacity and a high capacity retention rate after high-speed discharging and charging.

This is thought to be due to the following.

The copolymer contained in the polymer particles not only has an N-oxy radical in which two quaternary carbons are bonded as described above, but also has a repeating unit represented by the formula (1), The repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) are contained in a state of being bonded. As described above, since the repeating unit represented by the formula (3) is contained in a state of being bonded to the repeating unit represented by the formula (1), the polymer particles have an affinity for water (hydrophilicity). Sex) is considered to be higher. For this reason, it becomes easy to manufacture an electrode using the polymer particles. Also. Since the copolymer contained in the polymer particles contains the repeating unit represented by the formula (3), when the polymer particles are used as an electrode, the affinity for the electrolytic solution which is a highly polar solvent is obtained. Therefore, it is considered that the movement of lithium ions in the electrode can be made smooth and the diffusion resistance of lithium ions in the electrode can be reduced.

From the above, it is considered that this polymer particle is a polymer particle that becomes a suitable electrode for a lithium secondary battery when included in an electrode provided in the lithium secondary battery. The electrode active material composed of the polymer particles is suitable as an electrode active material for an electrode provided in a lithium secondary battery.

In the polymer particles, the copolymer has a content of the repeating unit represented by the formula (3) and a content of the repeating unit represented by the formula (1) and the content of the formula (3). Is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass in total with the content of the repeating unit represented by

According to such a configuration, it is possible to provide polymer particles from which a more suitable electrode can be manufactured by a lithium secondary battery.

This is because both the effect of having the repeating unit represented by the formula (1) and the effect of having the repeating unit represented by the formula (3) can be suitably exhibited. Conceivable.

において In the polymer particles, the copolymer preferably further contains a repeating unit represented by the following formula (4) in the molecule.

This is thought to be due to the following.

First, the copolymer contained in the polymer particles contains the repeating unit represented by the formula (4) in a state of being bonded to the repeating units represented by the formulas (1) to (3). Therefore, the copolymer is cross-linked. Due to such crosslinking, the polymer particles are considered to be excellent in anti-elution property (elution resistance) to a solvent. That is, it is considered that even when the polymer particles are used as an electrode, the elution of the polymer particles into the solvent contained in the electrolytic solution that comes into contact with the electrode can be more suitably suppressed.

Further, since the copolymer contained in the polymer particles is cross-linked by the repeating unit represented by the formula (4), the cross-linking is represented by the formulas (1) and (3). It is considered that each effect is less likely to be inhibited by having a repeating unit having the same structure.

Accordingly, it is considered that polymer particles having more excellent elution resistance can be obtained while exhibiting the respective effects sufficiently by having the repeating units represented by the formulas (1) and (3).

Further, a method for producing a polymer particle according to another aspect of the present invention is a method for producing the polymer particle, wherein the imino compound represented by the following formula (5) and the imino compound represented by the following formula (6) are provided. A first step of polymerizing a monomer composition containing (meth) acrylic acid and a second step of nitroxidizing the polymer obtained in the first step.

In the formula (5), R ⁶ represents a hydrogen atom or a methyl group.

In the formula (6), R ⁷ represents a hydrogen atom or a methyl group.

According to such a configuration, it is possible to suitably produce polymer particles that become electrodes suitable for a lithium secondary battery when included in an electrode provided in the lithium secondary battery.

This is thought to be due to the following.

First, in the first step, by polymerizing a monomer composition containing an imino compound represented by the formula (5) and (meth) acrylic acid represented by the formula (6), A copolymer containing the repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) in the molecule is obtained. In the second step, the copolymer (the polymer obtained in the first step) is nitroxidized, so that the imino group contained in the copolymer is nitroxidized. A part of the repeating unit represented is a repeating unit represented by the formula (1). From this, a copolymer containing the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the repeating unit represented by the formula (3) in a molecule is can get.

The polymer obtained in the first step is obtained in the form of particles, and the particles containing the polymer are in the form of a particulate polymer obtained by polymerizing only the imino compound represented by the formula (5). Since particles smaller than the coalesced particles are obtained, the particles containing the copolymer obtained in the second step are also reduced. From this, a copolymer containing the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), and the repeating unit represented by the formula (3) in a molecule is used. Thus, polymer particles having an average primary particle diameter of 0.01 to 20 μm are obtained.

In the method for producing polymer particles, the monomer composition preferably contains a crosslinking agent represented by the following formula (7).

According to such a configuration, among the polymer particles, polymer particles containing a copolymer further containing a repeating unit represented by the formula (4) in the molecule can be suitably produced. This is because the monomer composition to be polymerized in the first step contains the crosslinking agent represented by the formula (7), whereby the repeating unit represented by the formula (4) can be produced in the first step. It is considered that a copolymer crosslinked by the above is obtained.

In the method for producing polymer particles, it is preferable that the polymerization in the first step is suspension polymerization, emulsion polymerization, or dispersion polymerization.

According to such a configuration, the polymer particles can be produced more suitably. This is thought to be because the polymerization in the first step is suspension polymerization, emulsion polymerization, or dispersion polymerization, whereby a suitable particulate polymer is easily obtained in the first step. Can be

Further, in the method for producing polymer particles, the monomer composition is polymerized by adding a water-soluble solvent solution containing the monomer composition to an aqueous solution containing a surfactant and a polymerization initiator. Is preferred.

According to such a configuration, the polymer particles can be produced more suitably.

This is thought to be due to the following.

First, it is considered that the unreacted monomer, that is, the unreacted imino compound represented by the formula (5) or the like remaining in the particulate polymer obtained in the first step can be suppressed. . Specifically, the imino compound represented by the formula (5) is hydrophobic. The hydrophobic imino compound disperses as oil droplets in an aqueous solution containing a surfactant. When the monomer composition is polymerized in this state, the unreacted imino compound represented by the formula (5) precipitates in the aqueous solution together with the polymer, and is surrounded by the obtained polymer. Thus, it is considered that the unreacted imino compound represented by the formula (5) remains. The water-soluble solvent is water-soluble and can dissolve a monomer contained in the monomer composition, for example, an imino compound represented by the formula (5). By containing the water-soluble solvent, the obtained polymer swells. Therefore, the polymer existing so as to surround the unreacted imino compound represented by the formula (5) also swells, and from the state surrounded by the polymer, the unreacted formula Since the imino compound represented by the formula (5) can be eluted, the unreacted monomer, that is, the unreacted imino represented by the formula (5) is added to the particulate polymer obtained in the first step. It is considered that the compound and the like can be prevented from remaining.

Further, in the first step, by polymerizing a monomer composition containing an imino compound represented by the formula (5) and (meth) acrylic acid represented by the formula (6), It is considered that a copolymer containing the repeating unit represented by formula (2) and the repeating unit represented by formula (3) in a molecule can be suitably obtained. Specifically, as described above, the unreacted imino compound represented by the formula (5) remains so as to be surrounded by the obtained polymer. In this state, if the water-soluble solvent does not exist, the imino compound represented by the formula (5) exists while being surrounded by the polymer, and the (meth) acrylic acid represented by the formula (6) is present. Is thought to diffuse into an aqueous solution preferentially over the imino compound represented by the formula (5). In such a case, the polymerization of only the (meth) acrylic acid represented by the formula (6) takes precedence, and the repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) are intramolecularly combined. It is thought that it becomes difficult to obtain a copolymer containing. On the other hand, as described above, when a water-soluble solvent is contained, as described above, the imino compound represented by the formula (5) is also eluted from the state surrounded by the polymer, Such homopolymerization of the (meth) acrylic acid represented by the formula (6) is suppressed, and the imino compound represented by the formula (5) and the (meth) acrylic acid represented by the formula (6) are suppressed. It is considered that the polymerization of the copolymer containing the repeating unit represented by the formula (2) and the repeating unit represented by the formula (3) in the molecule is favorably polymerized.

From the above, by adding a water-soluble solvent solution containing the monomer composition to an aqueous solution containing a surfactant and a polymerization initiator, the monomer composition can be suitably polymerized, The united particles can be produced more suitably.

According to the present invention, it is possible to provide polymer particles capable of producing an electrode suitable for a lithium secondary battery when included in an electrode provided in the lithium secondary battery. Further, a method for producing the polymer particles can be provided.

本 Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto.

[Example 1]
(First step: polymerization step)
First, a first step of polymerizing a monomer composition containing the (meth) acrylic acid imino compound, the (meth) acrylic acid, and the crosslinking agent was performed. Specifically, in a 200 mL Erlenmeyer flask, 22.50 g (100 mmol) of 2,2,6,6-tetramethyl-4-piperidinyl methacrylate and 0.198 g (1.0 mmol) of ethylene glycol dimethyl methacrylate were added. ), 0.172 g (2.0 mmol) of methacrylic acid, 0.16 g (1.0 mmol) of α, α'-azobisisobutyronitrile as a polymerization initiator, and 30 mL of toluene, and mixed to obtain a uniform mixture. A solution was obtained.

Next, 200 mL of water and 0.5 g of sodium dodecylbenzenesulfonate as a surfactant were charged into a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser, and mixed. While maintaining the solution at 25 ° C., the homogeneous solution was added and dispersed with stirring. Subsequently, after oxygen in the reaction system was removed through nitrogen gas, the mixture was reacted at 60 ° C. for 6 hours with stirring. After completion of the reaction, the reaction solution was cooled to room temperature, filtered, washed with 500 mL of water and then with 500 mL of hexane, and dried under reduced pressure to obtain 21.2 g (yield: 93%) of a white powder. The obtained white powder contains a repeating unit represented by the formula (2), a repeating unit represented by the formula (3), and a repeating unit represented by the formula (4) in a molecule. Polymer particles composed of a copolymer (crosslinked polymethacrylic acid-based imino copolymer).

(Second step: nitroxidation)
Next, a second step of nitroxidation of the polymer obtained in the polymerization step was performed. Specifically, 10 g of the white powder obtained in the polymerization step, 0.73 g (2.2 mmol) of sodium tungstate dihydrate as a catalyst, and 300 mL of methanol were mixed with a stirrer, a nitrogen gas inlet tube, and a thermometer. , A reflux condenser, and a dropping funnel into a 500 mL four-necked flask. After removing oxygen in the reaction system through nitrogen gas while maintaining the temperature at 30 ° C., 50.40 g of 30% hydrogen peroxide solution ( (445 mmol) was added dropwise over 3 hours. After maintaining the temperature at 30 ° C. for 8 hours, the reaction solution was filtered, washed with 500 mL of methanol and then with 500 mL of water, and dried under reduced pressure to obtain 9.8 g of a red powder. This red powder is represented by the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4). (Cross-linked polymethacrylic acid-based nitroxide copolymer) containing a repeating unit in the molecule. The particle size distribution of the obtained red powder was observed with a scanning electron microscope (VE-8800 manufactured by Keyence Corporation) at a magnification of 1000 to 10,000 times and an acceleration voltage of 10 kV. A region containing 50 or more polymer particles in the observation field of view is randomly selected, a dark contrast is observed in the observed image, and a site that is connected continuously and linearly is determined as the contour of the primary particle, and the scale and By comparison, the diameters of the 50 or more primary particles were measured, and a graph of the particle size distribution was obtained using the horizontal axis as the diameter and the vertical axis as the number. From the obtained particle size distribution, the volume average particle diameter of the primary particle diameter was determined. The volume average particle diameter (average primary particle diameter) of the obtained primary particle diameter was 0.80 μm.

(Measurement of the content of the above (1) by a chemical titration method)
The content of (1) in the copolymer was measured by a chemical titration method based on a redox reaction (redox titration method). Specifically, 100 mg of a sample (copolymer) was weighed, swollen with chloroform and acetic acid, and then added with a 0.2 N potassium iodide aqueous solution, and the released iodine was back titrated with a 0.050 N aqueous sodium thiosulfate solution. It calculated by doing. In the test, two samples were analyzed, and the average value was used as the analysis value.

(Measurement of the content of (3) by the chemical titration method)
The content of (3) in the copolymer was measured by a chemical titration method based on a neutralization reaction. Specifically, 1.0 g of a sample (copolymer) was weighed, swollen with toluene, and then titrated with an ethanol solution of 0.050 N potassium hydroxide. In the test, two samples were analyzed, and the average value was used as the analysis value.

As a result of the measurement, the content of (3) [(3) / (1) + (3)] with respect to 100 parts by mass of the total content of (1) and (3) in the copolymer was , 0.65 parts by mass.

(Measurement of the content of the above (2))
The content of the repeating unit represented by the formula (2) was measured by a chemical titration method. Specifically, 1.0 g of a sample (copolymer) was weighed, swollen with methanol, and then titrated with 0.050N hydrochloric acid. In the test, two samples were analyzed, and the average value was used as the analysis value.

As a result of the measurement, the content of (1) [(1) / (1) + (2)] with respect to 100 parts by mass of the total content of (1) and (2) in the copolymer was , 91 parts by mass.

(Measurement of the content of the above (4))
The content of (4) is measured by subtracting the content of (1), the content of (2), and the content of (3) when the amount of the copolymer is 100 parts by mass. did.

As a result of the measurement, the content of (4) [(4) / (1) + (3)] with respect to 100 parts by mass of the total content of (1) and (3) in the copolymer was , 0.89 parts by mass.

[Example 2]
(First step)
A step similar to the first step in Example 1 was performed, except that 0.5 g of polyoxyethylene nonylphenyl ether was used instead of 0.5 g of sodium dodecylbenzenesulfonate. By the first step, 21.0 g (yield 92%) of white powder was obtained.

(2nd process)
The second step in Example 1 was repeated except that 0.54 g (2.2 mmol) of sodium molybdate dihydrate was used instead of 0.73 g (2.2 mmol) of sodium tungstate dihydrate. Similar steps were performed.

によって 9.8 g of red powder was obtained by the first step and the second step performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 4.6 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.66 parts by mass. The ratio of (1) / (1) + (2) was 94 parts by mass. The ratio of (4) / (1) + (3) was 0.85 parts by mass.

[Example 3]
(First step)
A step similar to the first step in Example 1 was performed, except that ethylene glycol dimethyl methacrylate was not used. By the first step, 20.4 g (yield 90%) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.7 g of red powder was obtained by the first step and the second step (the second step similar to Example 1) performed after the first step. The obtained red powder contains a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a repeating unit represented by the formula (3) in a molecule. Polymer particles composed of a copolymer (polymethacrylic acid-based nitroxide copolymer). The average primary particle size of the obtained red powder was 17 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.58 parts by mass. The ratio of (1) / (1) + (2) was 94 parts by mass. The ratio of (4) / (1) + (3) was 0 parts by mass.

[Example 4]
(First step)
In a 200 mL Erlenmeyer flask, 22.50 g (100 mmol) of 2,2,6,6-tetramethyl-4-piperidinyl methacrylate, 0.198 g (1.0 mmol) of ethylene glycol dimethyl methacrylate, 8 methacrylic acid 0.6 mg (0.1 mmol) and methanol (30 mL) were charged and mixed to obtain a homogeneous solution.

Next, 200 mL of water, 0.27 g (1.0 mmol) of potassium peroxodisulfate as a polymerization initiator were placed in a 500 mL four-necked flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, and a reflux condenser. And 0.5 g of sodium dodecylbenzenesulfonate as a surfactant was charged and mixed. While maintaining this solution at 25 ° C., the homogeneous solution was added and dispersed with stirring. Subsequently, after oxygen in the reaction system was removed through nitrogen gas, the mixture was reacted at 60 ° C. for 6 hours with stirring. After completion of the reaction, the reaction solution was cooled to room temperature, filtered, washed with 500 mL of water and then with 500 mL of hexane, and dried under reduced pressure to obtain 22.6 g (yield: 99%) of a white powder.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.9 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 1.8 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.04 parts by mass. The ratio of (1) / (1) + (2) was 95 parts by mass. The ratio of (4) / (1) + (3) was 0.70 parts by mass.

[Example 5]
(First step)
A step similar to the first step in Example 4 was performed, except that 0.086 g (1.0 mmol) of methacrylic acid was used instead of 8.6 mg (0.1 mmol) of methacrylic acid. By this first step, 21.2 g (94% yield) of white powder was obtained.

(2nd process)
A process similar to the second process in Example 1 was performed, except that 300 mL of toluene, 30 mL of water, and 1.0 g of trioctylmethylammonium chloride were used instead of 300 mL of methanol.

によって 9.9 g of red powder was obtained by the first step and the second step performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 0.53 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.38 parts by mass. The ratio (1) / (1) + (2) was 96 parts by mass. The ratio of (4) / (1) + (3) was 0.78 parts by mass.

[Example 6]
(First step)
A step similar to the first step in Example 4 was performed, except that 0.516 g (6.0 mmol) of methacrylic acid was used instead of 8.6 mg (0.1 mmol) of methacrylic acid. By this first step, 21.6 g (yield 93%) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.8 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 0.081 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 2.04 parts by mass. The ratio of (1) / (1) + (2) was 97 parts by mass. The ratio of (4) / (1) + (3) was 0.76 parts by mass.

[Example 7]
(First step)
A step similar to the first step in Example 4 was performed, except that 0.2 g of sodium dodecylbenzenesulfonate was used instead of 0.5 g of sodium dodecylbenzenesulfonate. By the first step, 20.9 g (yield 92%) of white powder was obtained.

(2nd process)
A step similar to the second step in Example 1 was performed, except that 300 mL of N, N-dimethylformamide was used instead of 300 mL of methanol.

によって 9.8 g of red powder was obtained by the first step and the second step performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was measured by the same method as in Example 1 and found to be 7.1 μm.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.35 parts by mass. The ratio of (1) / (1) + (2) was 90 parts by mass. The ratio of (4) / (1) + (3) was 0.77 parts by mass.

Example 8
(First step)
Using 200 mL of toluene instead of 200 mL of water, not using sodium dodecylbenzenesulfonate, and using 0.258 g (3.0 mmol) of methacrylic acid instead of 0.172 g (2.0 mmol) of methacrylic acid Steps similar to the first step in Example 1 except that 0.594 g (3.0 mmol) of ethylene glycol dimethyl methacrylate was used instead of 0.198 g (1.0 mmol) of ethylene glycol dimethyl methacrylate Was done. By this first step, 20.6 g (90% yield) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 8.9 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 5.9 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, (3) / (1) + (3) in the copolymer was 0.36 parts by mass. The ratio of (1) / (1) + (2) was 83 parts by mass. The ratio of (4) / (1) + (3) was 2.22 parts by mass.

[Example 9]
(First step)
A step similar to the first step in Example 4 was performed, except that 0.861 g (10.0 mmol) of methacrylic acid was used instead of 8.6 mg (0.1 mmol) of methacrylic acid. By this first step, 21.2 g (90% yield) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.7 g of red powder was obtained by the first step and the second step (the second step similar to Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 0.047 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 6.40 parts by mass. The ratio of (1) / (1) + (2) was 92 parts by mass. The ratio of (4) / (1) + (3) was 0.77 parts by mass.

[Comparative Example 1]
(First step)
A step similar to the first step in Example 1 was performed, except that methacrylic acid was not used. By the first step, 18.8 g (83% yield) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.8 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder contains a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a repeating unit represented by the formula (4) in a molecule. The polymer particles were composed of a copolymer (crosslinked polymethacrylic acid-based nitroxide copolymer). The average primary particle diameter of the obtained red powder was 34 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0 parts by mass. The ratio of (1) / (1) + (2) was 77 parts by mass. The ratio of (4) / (1) + (3) was 1.05 parts by mass.

[Comparative Example 2]
(First step)
A step similar to the first step in Example 4 was performed except that methacrylic acid was not used. By this first step, 19.3 g (yield 85%) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 9.6 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder contains a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a repeating unit represented by the formula (4) in a molecule. The polymer particles were composed of a copolymer (crosslinked polymethacrylic acid-based nitroxide copolymer). The average primary particle diameter of the obtained red powder was 38 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0 parts by mass. The ratio (1) / (1) + (2) was 67 parts by mass. The ratio of (4) / (1) + (3) was 0.90 parts by mass.

[Comparative Example 3]
(First step)
A process similar to the first process in Comparative Example 2 was performed, except that 0.396 g (2.0 mmol) of ethylene glycol dimethyl methacrylate was used instead of 0.198 g (1.0 mmol) of ethylene glycol dimethyl methacrylate. By this first step, 20.0 g (yield 87%) of white powder was obtained.

(2nd process)
1.45 g (4.4 mmol) of sodium tungstate dihydrate was used instead of 0.73 g (2.2 mmol) of sodium tungstate dihydrate, and 50.40% of a 30% aqueous hydrogen peroxide solution. (445 mmol) was replaced by 100.8 g (890 mmol) of 30% aqueous hydrogen peroxide, and the holding time at 30 ° C. after the dropwise addition of the 30% aqueous hydrogen peroxide was 16 hours. Except for this, the same step as the second step in Example 1 was performed.

によって 9.7 g of red powder was obtained by the first step and the second step performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 23 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0 parts by mass. The ratio of (1) / (1) + (2) was 64 parts by mass. The ratio of (4) / (1) + (3) was 0.94 parts by mass.

[Comparative Example 4]
(First step)
Using 200 mL of toluene instead of 200 mL of water, not using sodium dodecylbenzenesulfonate, and using 0.086 g (1.0 mmol) of methacrylic acid instead of 0.172 g (2.0 mmol) of methacrylic acid Except for this, the same step as the first step in Example 1 was performed. By the first step, 20.1 g (88% yield) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

によって 8.9 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 41 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.35 parts by mass. The ratio (1) / (1) + (2) was 59 parts by mass. The ratio of (4) / (1) + (3) was 0.49 parts by mass.

[Comparative Example 5]
(First step)
30 mL of THF was used instead of 30 mL of toluene, 200 mL of THF was used instead of 200 mL of water, no sodium dodecylbenzenesulfonate was used, and 0.172 g (2.0 mmol) of methacrylic acid was used instead of methacrylic acid 0 A step similar to the first step in Example 1 was performed, except that 0.086 g (1.0 mmol) was used. By the first step, 20.3 g (89% yield) of white powder was obtained.

(2nd process)
The same second step as in Example 1 was performed.

赤色 9.0 g of red powder was obtained by the first step and the second step (the second step similar to that in Example 1) performed after the first step. The obtained red powder is composed of the repeating unit represented by the formula (1), the repeating unit represented by the formula (2), the repeating unit represented by the formula (3), and the formula (4) The polymer particles consisted of a copolymer (cross-linked polymethacrylic acid-based nitroxide copolymer) containing the repeating unit represented by in the molecule. The average primary particle diameter of the obtained red powder was 29 μm as measured by the same method as in Example 1.

測定 When measured by the same method as in Example 1, the ratio (3) / (1) + (3) in the copolymer was 0.33 parts by mass. The ratio of (1) / (1) + (2) was 74 parts by mass. The ratio of (4) / (1) + (3) was 0.76 parts by mass.

粒子 The particles according to Examples 1 to 9 and Comparative Examples 1 to 5 were evaluated by the following method.

[Battery characteristics]
1 g of each of the particles according to Examples 1 to 8 and Comparative Examples 1 to 5, an aqueous binder composed of styrene butadiene fine particles (SBR) and sodium carboxymethyl cellulose (CMC-Na) (5% by mass based on each particle), A black slurry was obtained by mixing, pressing, kneading and stirring 1.0 g of carbon powder Super-P (manufactured by TIMCAL) and ion-exchanged water for adjusting the slurry viscosity. This slurry was applied on the surface of an aluminum foil (current collector) having a thickness of 18 μm using a late stage and an applicator with an application clearance of 100 μm, and then dried under reduced pressure at 120 ° C. for 3 hours. By doing so, electrodes were obtained in which the composite films of the particles and the carbon powder according to Examples 1 to 8 and Comparative Examples 1 to 5 were bound to the current collector. The obtained electrode was dried, and the dried electrode was subjected to a rolling treatment with a load of 4 tons using a roll press (manufactured by Hosen Co., Ltd.) and dried again.

複合 This composite electrode was cut out in a circle having a diameter of 13 mm and used as a positive electrode of a coin cell. On the other hand, a lithium metal foil (thickness 0.2 m, diameter 16 mm) is used for the counter electrode (negative electrode), a polypropylene-based separator (Celgard # 2400 manufactured by Polypore) is used for the separator, and an electrolyte is used for the electrolyte. Lithium secondary was added to a mixed solution of ethylene carbonate and dimethyl carbonate (mass ratio 3: 7) using an electrolytic solution in which LiPF6 was dissolved at 1 mol / L in a glove box under an argon atmosphere. A battery (coin half cell) was produced.

With respect to each lithium secondary battery having the above-described configuration, charge / discharge evaluation was performed at a constant current (33 μA / cm ² , 25 ° C.) using a charge / discharge test apparatus (TOSCAT3100 manufactured by Toyo System Corporation). Specifically, 1C discharge capacity, 10C discharge capacity, 10C charge capacity, and 10C discharge capacity retention rate (capacity retention rate at 10C discharge) were measured. The 10C discharge capacity retention rate is a discharge capacity in 1/10 hour (6 minutes) from a fully charged state, and indicates a capacity retention rate after high-speed discharge charging. The 10C discharge capacity retention rate is an index for a high-output secondary battery.

These results are shown in Table 1. In Table 1, “(3) / (1) + (3)” means the content (parts by mass) of (3) based on 100 parts by weight of the total content of (1) and (3). Show. “(1) / (1) + (2)” indicates the content (parts by mass) of (1) based on 100 parts by weight of the total content of (1) and (2). “(4) / (1) + (3)” indicates the content (parts by mass) of (4) relative to 100 parts by weight of the total content of (1) and (3).

From Table 1, it can be seen that the lithium secondary battery using the electrodes obtained using the particles according to Examples 1 to 9 has a 1 C discharge capacity, a 10 C discharge capacity, and a higher discharge capacity than the case using the particles according to Comparative Examples 1 to 5. It can be seen that both the 10C charge capacity and the 10C charge capacity maintenance rate are high. Specifically, the lithium secondary batteries using the electrodes obtained by using the particles according to Examples 1 to 9 showed a high actual capacity with respect to the theoretical charge capacity, and had high capacity efficiency.

From the above, a copolymer containing a repeating unit represented by the formula (1), a repeating unit represented by the formula (2), and a repeating unit represented by the formula (3) in a molecule It has been found that it is necessary that the average primary particle diameter is 0.01 to 20 μm in order to exhibit sufficiently good battery characteristics.

This application is based on Japanese Patent Application No. 2018-135624 filed on Jul. 19, 2018, the contents of which are included in the present application.

Although the present invention has been described above appropriately and sufficiently through the embodiments to express the present invention, those skilled in the art can easily modify and / or improve the above-described embodiments. Should be recognized. Therefore, unless a modification or improvement performed by those skilled in the art is at a level that departs from the scope of the claims set forth in the claims, the modification or the improvement will not be included in the scope of the claims. Is interpreted as being included in

According to the present invention, there is provided a polymer particle capable of producing an electrode suitable for a lithium secondary battery when included in an electrode provided in the lithium secondary battery. Further, according to the present invention, there is provided a method for producing the polymer particles.

Claims

Including a repeating unit represented by the following formula (1), a repeating unit represented by the following formula (2), and a copolymer containing a repeating unit represented by the following formula (3) in a molecule,
Polymer particles having an average primary particle diameter of 0.01 to 20 μm.

[In the formula (1), R 1 represents a hydrogen atom or a methyl group. ]

[In the formula (2), R 2 represents a hydrogen atom or a methyl group. ]

[In the formula (3), R 3 represents a hydrogen atom or a methyl group. ]
In the copolymer, the content of the repeating unit represented by the formula (3) is the same as the content of the repeating unit represented by the formula (1) and the content of the repeating unit represented by the formula (3). 2. The polymer particles according to claim 1, wherein the amount is 0.01 to 5 parts by mass based on 100 parts by mass in total.
3. The polymer particle according to claim 1, wherein the copolymer further contains a repeating unit represented by the following formula (4) in the molecule. 4.

[In the formula (4), R 4 and R 5 each independently represent a hydrogen atom or a methyl group, and Z represents an ethylene group, a propylene group, a butylene group, or —C 2 H 4 OC 2 H 4 −. Represents a group. ]
The method for producing polymer particles according to any one of claims 1 to 3, wherein
A first step of polymerizing a monomer composition containing an imino compound represented by the following formula (5) and (meth) acrylic acid represented by the following formula (6):
A second step of nitroxidizing the polymer obtained in the first step.

[In the formula (5), R 6 represents a hydrogen atom or a methyl group. ]

[In the formula (6), R 7 represents a hydrogen atom or a methyl group. ]
The method for producing polymer particles according to claim 4, wherein the monomer composition contains a crosslinking agent represented by the following formula (7).

[In the formula (7), R 8 and R 9 each independently represent a hydrogen atom or a methyl group, and Z represents an ethylene group, a propylene group, a butylene group, or —C 2 H 4 OC 2 H 4 −. Represents a group. ]
The method according to claim 4 or 5, wherein the polymerization in the first step is suspension polymerization, emulsion polymerization, or dispersion polymerization.
The first step polymerizes the monomer composition by adding a water-soluble solvent solution containing the monomer composition to an aqueous solution containing a surfactant and a polymerization initiator. A method for producing the polymer particles according to claim 5.