JP2009138130A - Method for producing composite and composite produced by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyquinoxaline compound having sufficient electrochemical properties without using a diaminobenzidine having a benzidine skeleton having extremely high toxicity as a raw material of a polyphenylquinoxaline compound of a negative electrode active material for a proton battery. <P>SOLUTION: The method for producing the composite of the polyquinoxaline compound represented by formula (1) (wherein, n is an integer of ≥20 and ≤200) and a carbon material includes polycondensing bisbenzyl and 3, 3', 4, 4'-tetraaminodiphenylmethane in the presence of the carbon material. The composite of the polyquinoxaline compound and the carbon material is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention produces a composite of a carbon material and a polymer by synthesizing a polymer having a specific quinoxaline skeleton by reacting a specific tetraketone compound and a specific tetraamine compound in the presence of a carbon material. And a composite produced by the method.

  Conventionally, nickel hydride batteries, nickel cadmium batteries, lithium batteries, and the like have been used as batteries used for portable terminals, portable electronic devices, and the like. These batteries are harmful or rare, sometimes cause fire accidents, and have problems in terms of pollution, resource depletion, and safety. Furthermore, there are problems such as slow charging, IR drop due to rapid discharge, and battery deterioration. In order to solve these problems, a proton battery has been proposed in which both positive and negative electrodes are organic molecules, an acidic solution having high conductivity is used as an electrolyte, and protons are used as electron carriers (Patent Document 1).

  In the original proton battery, polyaniline was used for both the positive and negative electrodes, but the energy density, electromotive force, etc. were not fully satisfactory. By using a composite in which the surface of powdery carbon is coated with an organic material as an electrode active material, the performance of the proton battery is greatly improved (Patent Document 2). Polypyridine was used for the negative electrode, but there were problems with energy density and cycleability, and sufficient practical performance was not achieved. By using polyphenylquinoxaline (PPQ) for the negative electrode and combining powdered carbon and polyphenylquinoxaline, sufficient energy density, electromotive force, and cycleability were achieved, and it was possible to put to practical use (Patent Document 3). .

  The proton battery negative electrode active material is polyphenylquinoxaline, which is synthesized by a polycondensation reaction of bisbenzyl (BBZ) and 3,3'-diaminobenzidine (DABZ) (reaction formula (A)). 3,3'-Diaminobenzidine has a strong mutagenic benzidine skeleton, and has a problem of containing benzidine as a production prohibition substance in its synthesis intermediate.

Patent No. 3039484 Japanese Patent No. 2974012 Japanese Patent No. 3144410

  An object of the present invention is to provide a polyquinoxaline compound having sufficient electrochemical performance without using a diaminobenzidine having a highly toxic benzidine skeleton as a raw material of a polyphenylquinoxaline compound as a proton battery negative electrode active material.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by using a polyquinoxaline compound having a non-benzidine skeleton as a negative electrode material of a proton battery, and completed the present invention. .
That is, the present invention relates to the following [1] to [8] polyquinoxaline composite and a method for producing the same.

[1] Condensation polymerization of bisbenzyl and 3,3 ′, 4,4′-tetraaminodiphenylmethane in the presence of a carbon material is represented by the following formula (1)

で示されるポリキノキサリン化合物（式中ｎは２０以上２００以下の整数を示す。）と炭素材料との複合物の製造方法。
［２］炭素材料が導電性炭素材料である［１］に記載の製造方法。
［３］導電性炭素材料が、カーボンブラック、アセチレンブラック、ケッチェンブラック、気相法炭素繊維からなる群から選ばれる少なくとも１種の炭素材料である［２］に記載の製造方法。
［４］溶媒の存在下に縮合重合を行うことを特徴とする［１］から［３］のいずれかに記載の製造方法。
［５］溶媒がジメチルホルムアミド、ジメチルアセトアミド、ｍ−クレゾール、ｏ−クレゾールからなる群から選ばれる少なくとも１種の溶媒である［４］に記載の製造方法。
［６］ビスベンジルと３，３’，４，４’−テトラアミノジフェニルメタンを炭素材料の存在下に縮合重合することを特徴とする
下記式（１）

A method for producing a composite of a polyquinoxaline compound (wherein n represents an integer of 20 or more and 200 or less) and a carbon material.
[2] The production method according to [1], wherein the carbon material is a conductive carbon material.
[3] The production method according to [2], wherein the conductive carbon material is at least one carbon material selected from the group consisting of carbon black, acetylene black, ketjen black, and vapor grown carbon fiber.
[4] The production method according to any one of [1] to [3], wherein condensation polymerization is performed in the presence of a solvent.
[5] The production method according to [4], wherein the solvent is at least one solvent selected from the group consisting of dimethylformamide, dimethylacetamide, m-cresol, and o-cresol.
[6] A condensation polymerization of bisbenzyl and 3,3 ′, 4,4′-tetraaminodiphenylmethane in the presence of a carbon material, the following formula (1)

で示されるポリキノキサリン化合物（式中ｎは２０以上２００以下の整数を示す。）と炭素材料との複合物。
［７］炭素材料が導電性炭素材料である［６］に記載の複合物。
［８］導電性炭素材料が、カーボンブラック、アセチレンブラック、ケッチェンブラック、気相法炭素繊維からなる群から選ばれる少なくとも１種の炭素材料である［７］に記載の複合物。

A composite of a polyquinoxaline compound (wherein n represents an integer of 20 or more and 200 or less) and a carbon material.
[7] The composite according to [6], wherein the carbon material is a conductive carbon material.
[8] The composite according to [7], wherein the conductive carbon material is at least one carbon material selected from the group consisting of carbon black, acetylene black, ketjen black, and vapor grown carbon fiber.

  The composite produced by the production method of the present invention is a material having performance equivalent to that of a polymer having a conventional quinoxaline skeleton, and a raw material having a highly toxic benzidine skeleton is not used. It can be manufactured safely.

The specific contents of the present invention will be described in detail below.
The composite of the polyquinoxaline compound (PPQM) of the present invention and a carbon material is obtained by dehydrating bisbenzyl (BBZ) and 3,3 ′, 4,4′-tetraaminodiphenylmethane (TADM) in a solvent in the presence of the carbon material. It is synthesized by condensation (reaction formula (B)). Here, “composite” is a generic term for a state in which a polymer is coated on the surface of a carbon material, or a state in which a carbon material and a polymer are mixed.

この重縮合に際しては、溶媒の存在下において行うことが好ましい。ここで、重合時の溶媒中のモノマー濃度としては、ビスベンジルと３，３’，４，４’−テトラアミノジフェニルメタンの質量の総計が全質量の５質量％以上４０質量％以下が好ましく、８質量％以上３０質量％以下が特に好ましい。モノマー濃度が低すぎると重合が進みにくく分子量が伸びない。ポリキノキサリン化合物（ＰＰＱＭ）と炭素材料との複合は、ポリキノキサリン化合物（ＰＰＱＭ）が炭素材料を被覆する形式が好ましいが、モノマー濃度が高すぎると重合溶液の粘度が上がり、混合しづらくなり、炭素材料への被覆が不均一となる。また、重合体の析出が早期に起こり分子量が伸びにくい。

This polycondensation is preferably performed in the presence of a solvent. Here, as a monomer concentration in the solvent at the time of polymerization, the total mass of bisbenzyl and 3,3 ′, 4,4′-tetraaminodiphenylmethane is preferably 5% by mass or more and 40% by mass or less, and 8% by mass. % To 30% by mass is particularly preferable. If the monomer concentration is too low, polymerization does not proceed easily and the molecular weight does not increase. The composite of the polyquinoxaline compound (PPQM) and the carbon material is preferably a type in which the polyquinoxaline compound (PPQM) coats the carbon material. However, if the monomer concentration is too high, the viscosity of the polymerization solution increases and mixing becomes difficult. The coating on the material becomes non-uniform. Moreover, polymer precipitation occurs early and the molecular weight is difficult to increase.

The reaction temperature is from room temperature to the reflux temperature of the solvent. It is preferably 100 ° C to 180 ° C.
The reaction time is 10 to 60 hours, preferably 20 to 40 hours.
After completion of the reaction, the copolymer is usually formed as a precipitate. The precipitate is removed by filtration, the solvent adhering to the precipitate is washed with an organic solvent having a low boiling point, such as methanol, and the removed wet solid is dried with a drier to obtain a copolymer. The drying conditions may be any conditions that allow the solvent used in the copolymerization reaction to evaporate. In general, heating drying is used, and heating vacuum drying is preferably used.

  The higher the molecular weight of the polyquinoxaline compound obtained by the present invention, the better the durability as an electric material. The weight average molecular weight is preferably 20000 or more, and more preferably 40000 or more. Moreover, it is more preferable that the low molecular weight body less than 5000 is 5 mass% or less. In addition, in this specification, a weight average molecular weight means the weight average molecular weight of polystyrene conversion measured by GPC.

That is, in terms of the molecular weight, in other words, using the number of repeating units n in the polyquinoxaline compound described in the formula (1), in the present invention, n is an integer of 20 or more and 200 or less, preferably 41 or more, 81 or more is more preferable. Moreover, it is more preferable that the low molecular weight material having n of less than 11 is 5% by mass or less.

  Although there is no restriction | limiting in particular in the solvent which can be used by this invention, If the monomer to be used is easy to melt | dissolve and does not react, what can be used can be used. Nitrogen-containing solvents such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone, sulfur-containing solvents such as dimethyl sulfoxide and sulfolane, phenol-based solvents such as m-cresol and o-cresol, etc. Are preferably used.

The carbon material used in the present invention will be described. The carbon material in the present application is a material mainly composed of simple carbon. A fine powdery carbon material is generally preferable because it exhibits conductivity, and a so-called conductive carbon material is preferable. The conductive carbon material for coating the polyquinoxaline compound is not particularly limited, but a material having high conductivity, a large specific surface area, and a small particle size is preferable. However, if the specific surface area is too large or the particle size is too small, the activity becomes high and side reactions are likely to occur, and the resulting composite becomes bulky and the energy density per volume (Wh / L) is high. Sometimes it gets smaller. Accordingly, preferred ranges thereof include a conductivity of 0.1 S / cm or more at room temperature, a specific surface area of 1,000 to 100,000 m ² / g by BET method, an average particle size (secondary measured by a centrifugal sedimentation type particle size distribution meter). The agglomerated particle diameter is 1 μm or more and 20 μm or less. Specific examples of these conductive carbon materials include carbon blacks such as ketjen black and acetylene black, activated carbons such as coconut shell activated carbon, carbon fibers such as air-layer carbon fiber, carbon fiber and carbon nanotube, natural graphite, artificial graphite Examples thereof include graphites such as graphite.

  The carbon material can be added together with the raw materials bisbenzyl (BBZ) and 3,3 ′, 4,4′-tetraaminodiphenylmethane (TADM) in a solvent. The amount of the carbon material added is preferably in the range of 5/95 to 50/50, particularly preferably 8/92 to 30/70, with respect to the resulting copolymer. If the amount of the carbon material added is too small, the coating amount of the polymer is too large, and the electrical conductivity is lowered. If the carbon material is added too much, the resulting composite becomes bulky and difficult to mold, and the amount of the copolymer containing the quinoxaline structural unit, which is the active substance in the electrode, as a repeating structure decreases, resulting in a composite. This is not preferable because the battery capacity per unit volume and mass is reduced.

  In order to use the composite of the polyquinoxaline compound and the carbon material in the present invention as an electrode, appropriate conductivity is required. For this purpose, the composite is preferably used after being pulverized to an appropriate particle size. As a preferable particle diameter, an average particle diameter (for example, a secondary aggregation particle diameter measured by a centrifugal sedimentation type particle size distribution meter) is 1 μm or more and 20 μm or less, and a maximum particle diameter is 200 μm or less. More preferably, the average particle size is 1 μm or more and 15 μm or less, and the maximum particle size is 100 μm or less. Here, the method for measuring the maximum particle size is the same as that for measuring the average particle size. The pulverization method is not particularly limited, and examples thereof include wet methods such as a bead mill, and dry methods such as a pulverizer, a bantam mill, a ball mill, a jet mill, and a pin mill. The conductivity of the composite thus pulverized is preferably 0.1 S / cm or more, and more preferably 0.2 S / cm or more as a volume conductivity at 25 ° C.

  The composite of the polyquinoxaline compound and the carbon material in the present invention can be used as an electrode material for a battery, particularly a proton battery. The structure of the proton battery basically has a laminated structure of a positive electrode / ion conductive layer / negative electrode, but the composite of the polyquinoxaline compound and the carbon material of the present invention is useful as a negative electrode material.

  Hereinafter, the present invention will be described in detail by way of typical examples. These are merely examples for explanation, and the present invention is not limited to these.

<Preparation of each composite>
Example 1 Synthesis of Polyquinoxaline Compound / Ketjen Black Complex (PPQM · KB) 1 L with a capacity of 600 g of N, N-dimethylformamide (hereinafter abbreviated as “DMF”, a reagent special grade manufactured by Pure Chemical Co., Ltd.) 34.2 g (100 mmol) of bisbenzyl and 22.3 g (100 mmol) of 3,3 ′, 4,4′-tetraaminodiphenylmethane were added to a glass separable flask (with stirring and cooling tube), and a nitrogen atmosphere at room temperature Stirred under for 10 minutes. Thereafter, 18.5 g of ketjen black (ECP600JD was used, hereinafter abbreviated as “KB”) was added, and the mixture was allowed to react at 130 ° C. for 20 hours while introducing air by bubbling. The obtained yellow-orange precipitate was filtered, washed with methanol, and vacuum dried at 130 ° C. for 12 hours to obtain 68.7 g of PPQM · KB black powder. The elemental analysis values (wt%) of this powder were C: 86.77, H: 3.29, N: 8.60, and the composite ratio was calculated as PPQ: KB = 76: 24 by mass ratio. Further, the absolute molecular weight (weight average) by light scattering from GPC using hexafluoroisopropanol as an eluent was 32,000.

Comparative Example 1 Synthesis of Polyphenylquinoxaline / Ketjen Black Complex (PPQ · KB) Using 34.24 g (100 mmol) of bisbenzyl (BBZ) and 22.23 g (100 mmol) of 3,3′-diaminobenzidine, Without using aldehyde (TPAL)
68.6 g of PPQ · KB black powder was obtained in the same manner as in Example 1 except that polymerization was performed in a nitrogen atmosphere instead of air bubbling. The elemental analysis values (wt%) of this powder were C: 86.75, H: 3.30, N: 8.61, and the composite ratio was calculated as PPQ: KB = 76: 24 in terms of mass ratio. The absolute molecular weight (weight average) was 27000.

<Measurement of conductivity of each composite>
Example 2: Conductivity measurement of composite (PPQM · KB) The black powder (PPQM · KB) obtained in Example 1 was vacuum-dried at 100 ° C for 14 hours and then weighed about 0.9 g in a dry air atmosphere. In addition, about 0.1 g of Polyflon (registered trademark, manufactured by Daikin Industries, Ltd.) as a binder was pulverized with an analytical mill (20000 rpm). About 0.1 g of this pulverized product was press-molded with a tablet molding machine having a diameter of 13 mm to obtain a pellet electrode. The conductivity of these pellet electrodes was measured by a 4-terminal direct current method. The results are shown in Table 1.
Comparative Example 2: Conductivity Measurement of Composite (PPQ · KB) The conductivity of the black powder (PPQ · KB) obtained in Comparative Example 1 was measured in the same manner as in Example 2. The results are shown in Table 1.

＜電池の調製＞
参考例１：ポリアニリン（ＰＡｎ）の合成
１Ｎ塩酸５００ｍｌ中アニリン０．２２モルを０．０５モル過硫酸アンモニウム存在下１時間攪拌した。反応液が青緑に変化し得られた沈殿物をガラスフィルターで濾過し、これを１Ｎ塩酸で洗浄後、１００℃１４時間真空乾燥し青緑色の目的物１２ｇを得た。目的物をアンモニア水溶液で中和し得られた濃紫色の元素分析、ＩＲから目的物はポリアニリ
ンの構造であると推定された。Ｎーメチルピロリドン中でのＧＰＣの結果から、分子量（ＰＭＭＡ換算）は数平均で約５００００、重量平均で約１２００００であった。

<Preparation of battery>
Reference Example 1: Synthesis of polyaniline (PAn) 0.22 mol of aniline in 500 ml of 1N hydrochloric acid was stirred for 1 hour in the presence of 0.05 mol of ammonium persulfate. The precipitate obtained by changing the reaction solution to blue-green was filtered through a glass filter, washed with 1N hydrochloric acid, and then vacuum-dried at 100 ° C. for 14 hours to obtain 12 g of a blue-green target product. From the IR analysis of the deep purple color obtained by neutralizing the target product with an aqueous ammonia solution, the target product was estimated to have a polyaniline structure. From the result of GPC in N-methylpyrrolidone, the molecular weight (in terms of PMMA) was about 50,000 in terms of number average and about 120,000 in terms of weight average.

Reference Example 2: Production of PAn positive electrode An excess of the PAn powder synthesized in Reference Example 1, acetylene black, VGCF (registered trademark, Showa Denko vapor phase carbon fiber), and polyvinylidene fluoride 85: 7: 1: 7 N-methylpyrrolidone was added to obtain a gel composition. After applying this composition onto a platinum mesh current collector 1 × 1 cm on a platinum plate with lead wires, press molding of 1 ton and vacuum drying at 80 ° C. for 8 hours to prepare a PAn electrode (average 200 mg) did.

Example 3 Preparation of Proton Battery of Composite (PPQM · KB) The PAn positive electrode manufactured in Reference Example 2 and then a 1 mm thick glass fiber separator (25 μm, 1.2 × 1.2 cm) were stacked. Subsequently, the composite electrode manufactured in Example 2 formed by pressure molding on a platinum net on a platinum plate with a lead wire was stacked. After pressurizing and adhering these laminated bodies, both ends were fixed with a polyimide tape. Then, this laminate was put in an aluminum laminate outer package and taken out outside so as not to short-circuit the two platinum lead wires. Next, 20% sulfuric acid aqueous solution was injected into the exterior body as an electrolyte, and the exterior body was brought into close contact while extracting excess sulfuric acid aqueous solution under reduced pressure, then sealed by heat fusion, and then PPQM / KB composite PAn proton Batteries (secondary batteries) (each n = 3) were prepared. When this battery was charged / discharged at 25 ° C., operating voltage 0-0.8 V, current 2 mA, 10 mA, a clear charge / discharge behavior was shown, and the maximum maximum discharge capacity per 1 g PPQ was measured. The results are shown in Table 2.

Comparative Example 3 Preparation of Proton Battery of Composite (PPQ · KB) Using the composite electrode (PPQ · KB) manufactured in Comparative Example 2, a proton battery was prepared in the same manner as in Example 3 (n = 3) The maximum discharge capacity was measured. The results are shown in Table 2.

Claims (8)

Bisbenzyl and 3,3 ′, 4,4′-tetraaminodiphenylmethane are subjected to condensation polymerization in the presence of a carbon material.

A method for producing a composite of a polyquinoxaline compound (wherein n represents an integer of 20 or more and 200 or less) and a carbon material.   The manufacturing method according to claim 1, wherein the carbon material is a conductive carbon material.   The production method according to claim 2, wherein the conductive carbon material is at least one carbon material selected from the group consisting of carbon black, acetylene black, ketjen black, and vapor grown carbon fiber.   The production method according to any one of claims 1 to 3, wherein the condensation polymerization is carried out in the presence of a solvent.   The production method according to claim 4, wherein the solvent is at least one solvent selected from the group consisting of dimethylformamide, dimethylacetamide, m-cresol, and o-cresol. Bisbenzyl and 3,3 ′, 4,4′-tetraaminodiphenylmethane are subjected to condensation polymerization in the presence of a carbon material.

A composite of a polyquinoxaline compound (wherein n represents an integer of 20 or more and 200 or less) and a carbon material.   The composite according to claim 6, wherein the carbon material is a conductive carbon material.   The composite according to claim 7, wherein the conductive carbon material is at least one carbon material selected from the group consisting of carbon black, acetylene black, ketjen black, and vapor grown carbon fiber.