WO2012161266A1

WO2012161266A1 - Reaction vessel and method for producing polymer using said vessel

Info

Publication number: WO2012161266A1
Application number: PCT/JP2012/063356
Authority: WO
Inventors: 大見　忠弘; 井上　利洋; 充則元田
Original assignee: 国立大学法人東北大学; 日本ゼオン株式会社
Priority date: 2011-05-25
Filing date: 2012-05-24
Publication date: 2012-11-29
Also published as: JPWO2012161266A1

Abstract

[Problem] The purpose of the invention is to provide a reaction vessel which uses an aluminum alloy vessel main body which has high thermal conductivity and in which excellent heat removal efficiency is expected, and which is capable of reducing generation of polymeric scales and microscopic condensates. [Solution] The aluminum alloy reaction vessel according to the present invention is characterized in that the inner surface of the aluminum alloy vessel main body is formed with an anodic oxide coating and an antistaining coating in this order.

Description

Reaction vessel and polymer production method using the vessel

The present invention relates to a reaction vessel, and more particularly, to a reaction vessel that can efficiently remove reaction heat, has little polymerization scale adherence and fine coagulum formation during the reaction, and can be operated for a long time. The present invention also relates to a method for producing a polymer using such a reaction vessel, particularly a binder for an electrochemical element (binder).

Polymer latex is widely used as a binder for fixing an electrode active material or the like to a current collector in an electrochemical element such as a secondary battery or a capacitor. These polymer latexes are usually produced by emulsion polymerization. In emulsion polymerization, typically, a polymerizable monomer (hereinafter sometimes simply referred to as “monomer”) is emulsified and dispersed in a dispersion medium using a surfactant or a water-soluble polymer protective colloid. It is done in the state. For emulsion polymerization, various monomers are used alone or in combination of two or more.

During emulsion polymerization, polymerization is performed while stirring the monomer emulsion with a stirring blade. At this time, the polymer particles aggregate due to mechanical shearing force due to stirring, and the particles adhere to the reaction vessel wall and the stirring blade (the deposit is called a polymerization scale), or a fine coagulum (fine coagulum). The situation that exists in the dispersion medium is likely to occur. If the polymerization scale adheres to the reaction vessel wall, the heat removal capability is lowered and it becomes difficult to control the reaction, so it is necessary to remove it. However, the removal work of a polymerization scale requires time and expense, and causes a decline in productivity. In addition, when the polymer latex containing this is used in the various applications described above, the fine coagulum is reduced by pre-filtering in order to significantly reduce operability and make the final product non-uniform. It is necessary to separate and remove the coagulum. This is economically disadvantageous because it leads to an increase in process and a decrease in polymer yield. In addition, depending on the size of the fine coagulum, it cannot be separated and removed by filtration or the like, and may remain as coarse particles in the product latex. If such a polymer latex containing coarse particles is used for, for example, an electrochemical device, it causes streaks and further causes contamination of the coating apparatus and peripheral equipment, which is not preferable.

Therefore, in order to prevent aggregation of polymer particles and to reduce the occurrence of polymerization scale, it has been proposed to provide a non-contaminating film on the inner surface of the reaction vessel (Patent Document 1, etc.).

Further, Patent Document 2 proposes to provide a non-contaminating film in order to prevent the adhesion of contaminants to the building exterior and vehicle exterior. In the example of Patent Document 2, the anti-contamination property is evaluated by providing a coating on an aluminum plate.

JP-A-5-023652 JP-A-8-337771

However, the reaction vessel main body in Patent Document 1 is made of glass. Glass reactors have low thermal conductivity and inadequate heat removal efficiency. Especially when a polymerization reaction with a high calorific value is performed, continuous operation becomes impossible unless measures such as forced cooling are used, which is economically disadvantageous. become.

Further, as a result of investigation by the present inventors, when a non-contaminating film is directly provided on the inner surface of an aluminum container body as in Patent Document 2, aluminum is eluted from the aluminum container body depending on reaction conditions. It has been found that polymer coagulation is more likely to occur.

The present invention has been made in view of the prior art as described above, and uses an aluminum alloy container main body that has high thermal conductivity and is expected to have excellent heat removal efficiency. It aims at providing the reaction container which can reduce generation | occurrence | production. Another object of the present invention is to provide a method for producing a polymer using such a reaction vessel. As a result of intensive studies to achieve this purpose, the aluminum body of the aluminum alloy was anodized and the surface of the container body was passivated. It has been found that elution is prevented and the occurrence of polymerization scale can be reduced, and the present invention has been completed.

The present invention for solving the above-mentioned problems includes the following matters as a gist.
(1) An aluminum alloy reaction vessel in which an anodized film and a non-contaminating film are formed in this order on the inner surface.

(2) The aluminum alloy reaction vessel according to (1), wherein the anodized film is a nonporous anodized film.

(3) The aluminum alloy reaction vessel according to (1), wherein the anodic oxide coating is a nonporous anodic oxide coating anodized using a non-aqueous solution.

(4) A method for producing a polymer, wherein a polymerizable monomer is polymerized in the reaction vessel described in any one of (1) to (3) above.

(5) The polymerizable monomer is an aliphatic conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, an ethylenically unsaturated carboxylic acid ester monomer, an alkenyl aromatic monomer, or cyanide. The method for producing a polymer according to (4), wherein the polymer is one or more monomers selected from the group consisting of vinyl monomers and unsaturated carboxylic acid amide monomers.

(6) The method for producing a polymer according to (5), wherein the polymerizable monomer further contains a monomer copolymerizable with the monomer described in (5).

(7) The method for producing a polymer according to (4), wherein emulsion polymerization is performed by adding at least a part of the polymerizable monomer in a reaction vessel in the form of an emulsion.

(8) The method for producing a polymer according to (7), wherein a surfactant, a water-soluble polymer protective colloid or an alkali-soluble resin is used as an emulsifier for the preparation of the monomer emulsion.

(9) The method for producing a polymer according to (7), wherein the monomer emulsion does not contain a polymerization initiator.

(10) The method for producing a polymer according to (7), wherein all of the polymerizable monomer is added to the reaction vessel in the form of an emulsion.

(11) The method for producing a polymer according to (4), wherein the polymerization is started after supplying the entire amount of the polymerizable monomer to the reaction vessel.

(12) After supplying a part of the polymerizable monomer to the reaction vessel, the polymerization is started, and the remaining polymerizable monomer is sequentially supplied to the reaction vessel, The production of the polymer according to (4) Method.

(13) The method for producing a polymer according to (4), wherein the polymerizable monomer is supplied after the seed latex is charged in a reaction vessel in advance.

(14) The method for producing a polymer according to (13), wherein the total monomer composition of the polymerizable monomer and the monomer composition of the latex for seed are the same.

(15) The method for producing a polymer according to (13), wherein a total monomer composition of the polymerizable monomer is different from a monomer composition of the seed latex.

(16) The method for producing a polymer according to any one of (4) to (15), wherein the obtained polymer is a binder for an electrochemical element.

According to the present invention, there can be provided a reaction vessel that can efficiently remove reaction heat, has little polymerization scale adherence and fine coagulated product during the reaction, and can be operated for a long time. Moreover, this invention provides the manufacturing method of the polymer using this reaction container, especially the binder for electrochemical elements.

1 is a cross-sectional view of an embodiment of an aluminum alloy reaction vessel according to the present invention.

Hereinafter, an aluminum alloy reaction vessel and a polymer production method using the same according to the present invention will be sequentially described.

(Aluminum alloy reaction vessel)
FIG. 1 shows a schematic cross-sectional view of an embodiment of an aluminum alloy reaction vessel according to the present invention, but the shape and the like of the reaction vessel of the present invention are not limited to this. As shown in FIG. 1, an aluminum alloy reaction vessel 10 has an anodized film 2 and a non-contaminating film 3 formed in this order on the inner surface of an aluminum alloy container body 1.
In the present invention, the anodic oxide coating refers to an oxide coating formed using the inner surface of the container as an anode.

The aluminum alloy container body 1 is made of a metal mainly composed of aluminum. The metal mainly composed of aluminum is a metal containing 50% by mass or more of aluminum, and may be pure aluminum. Preferably, the metal contains 80% by mass or more of aluminum, more preferably 90% by mass or more, and still more preferably 94% by mass or more of aluminum. The metal containing aluminum as a main component may be pure aluminum, but may contain any other metal capable of forming an alloy with aluminum as necessary, or may contain two or more kinds. Although the kind of metal is not specifically limited, As a preferable metal, at least 1 or more types of metal chosen from the group which consists of magnesium, titanium, and a zirconium is mentioned. Of these, magnesium is particularly preferred because it has the advantage of improving the strength of the aluminum substrate.

Furthermore, the metal mainly composed of aluminum may be a metal mainly composed of high-purity aluminum in which the content of specific elements (iron, copper, manganese, zinc, chromium) is suppressed. The total content of these specific elements is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. The metal containing high-purity aluminum as a main component may be pure aluminum, but may contain any other metal capable of forming an alloy with aluminum as required, or may contain two or more kinds. . The type of metal is not particularly limited as long as it is other than the above-mentioned specific elements, but preferred metals include at least one metal selected from the group consisting of magnesium, titanium and zirconium. Of these, magnesium is particularly preferred because it has the advantage of improving the strength of the aluminum substrate. The magnesium concentration is not particularly limited as long as it can form an alloy with aluminum, but is usually 0.5% by mass or more, preferably 1.0% by mass or more, in order to provide sufficient strength improvement. Preferably it is 1.5 mass% or more. In order to form a uniform solid solution with aluminum, it is preferably 6.5% by mass or less, more preferably 5.0% by mass, still more preferably 4.5% by mass or less, and most preferably 3% by mass. It is as follows.

In addition, the metal mainly composed of aluminum or the metal mainly composed of high-purity aluminum may contain other metal components as a crystal modifier. There is no particular limitation as long as it has a sufficient effect on crystal control, but zirconium or the like is preferably used.

When these other metals are included, the content thereof is usually 0.01% by mass or more, preferably 0.05% by mass or more, based on the whole metal mainly containing aluminum or high-purity aluminum. More preferably, the content is 0.1% by mass or more. This is because the characteristics of the other added metals are sufficiently exhibited. However, it is usually 20% by mass or less, preferably 10% by mass or less, more preferably 6% by mass or less, particularly preferably 4.5% by mass or less, and most preferably 3% by mass or less. Aluminum and other metal components form a uniform solid solution, and in order to maintain good material properties, it is better to have less than this.

The shape, size, side wall thickness, etc. of the aluminum alloy container main body 1 may be appropriately set according to the purpose and environment of use of the reaction container. Moreover, the shaping | molding method of the aluminum alloy container main body 1 is not specifically limited, It shape | molds in a predetermined shape by various methods.

An anodized film 2 is formed on the inner surface of the aluminum alloy container body 1. The anodic oxide coating 2 is formed by anodizing the inner surface of the aluminum alloy container body 1 in a chemical conversion solution having a predetermined composition.

The anodized film 2 is a film made of an oxide of a metal whose main component is aluminum and has a thickness of 10 nm or more. This film is a passive film, and when it is formed on the inner surface of the aluminum alloy container body 1, it exhibits high performance as a protective film.

The film thickness of the anodized film 2 is preferably 100 μm or less. If the film is thick, cracks are likely to occur and outgas is likely to be released. Therefore, the thickness of the anodic oxide coating 2 is more preferably 10 μm or less, still more preferably 1 μm or less, still more preferably 0.8 μm or less, and particularly preferably 0.6 μm or less. However, the film thickness is 10 nm or more. If the thickness of the anodic oxide coating 2 is too thin, sufficient corrosion resistance cannot be obtained. Therefore, the thickness of the anodic oxide coating 2 is preferably 20 nm or more, more preferably 30 nm or more.

As such an anodic oxide coating 2, an oxide film of a non-porous metal having no micropores or pores is suitable. Compared to the porous metal oxide film having a porous structure that has been used in the past, the nonporous metal oxide film is thin but has excellent corrosion resistance and has almost no fine pores or pores, so that moisture and the like can be removed. There is an advantage that it is difficult to adsorb.

The anodized film 2 is obtained by anodizing the inner surface of the aluminum alloy container body 1 using a chemical conversion solution having a pH of 4 to 10. This method has an advantage that a dense and non-porous anodic oxide coating 2 can be obtained.

Further, this method has a function of repairing defects caused by non-uniformity of the metal surface, and therefore has an advantage that a dense and smooth anodic oxide film 2 can be formed. The chemical conversion liquid is usually pH 4 or higher, preferably 5 or higher, more preferably 6 or higher. The pH of the chemical conversion solution is usually 10 or less, preferably 9 or less, more preferably 8 or less. In order to prevent the anodic oxide coating 2 formed by anodic oxidation from being dissolved in the chemical conversion liquid, it is desirable that the pH of the chemical conversion liquid is close to neutrality.

The chemical conversion liquid preferably exhibits a buffering action in the range of pH 4 to 10 in order to buffer the concentration fluctuation of various substances during anodization and keep the pH within a predetermined range. For this reason, it is desirable to include compounds such as acids and salts that exhibit a buffering action. The type of such a compound is not particularly limited, but is preferably at least one selected from the group consisting of boric acid, phosphoric acid, organic carboxylic acid, and salts thereof from the viewpoint of high solubility in the chemical conversion solution and good dissolution stability. is there. More preferably, it is an organic carboxylic acid or a salt thereof that hardly contains boron or phosphorus elements in the anodic oxide coating 2.

The organic carboxylic acid only needs to have one or more carboxyl groups, and may have a functional group other than the carboxyl group. For example, formic acid can also be preferably used. In terms of high solubility in the chemical conversion solution and good dissolution stability, aliphatic carboxylic acids are preferable, and aliphatic dicarboxylic acids having 3 to 10 carbon atoms are particularly preferable. Examples of the aliphatic dicarboxylic acid include, but are not limited to, malonic acid, maleic acid, fumaric acid, succinic acid, tartaric acid, itaconic acid, glutaric acid, dimethylmalonic acid, citraconic acid, citric acid, adipic acid, heptanoic acid, pimeline. Examples include acid, suberic acid, azelaic acid, and sebacic acid. Of these, tartaric acid, citric acid, and adipic acid are particularly preferred for reasons such as solution stability, safety, and good buffer action. Of these, one type may be used, or two or more types may be used in combination.

The salt of boric acid, phosphoric acid and organic carboxylic acid may be a salt of these acids with an appropriate cation. The cation is not particularly limited, and for example, ammonium ion, primary, secondary, tertiary or quaternary alkyl ammonium ion, alkali metal ion, phosphonium ion, or sulfonium ion can be used. Of these, ammonium ions, primary, secondary, tertiary or quaternary alkylammonium ions are preferred in that they are less affected by residual metal ions on the surface, ion diffusion, and the like. The alkyl group of the alkyl ammonium ion may be appropriately selected in consideration of the solubility in the chemical conversion solution, but is usually an alkyl group having 1 to 4 carbon atoms.

These compounds may be used alone or in combination of two or more. Further, the chemical conversion liquid may contain other compounds in addition to the above compounds.

The concentration of these compounds may be appropriately selected according to the purpose, but is usually 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 1% by mass or more with respect to the whole chemical conversion liquid. . In order to increase the electrical conductivity and sufficiently form the anodic oxide coating 2, it is desirable that the concentration of the compound be as high as possible. However, it is usually 30% by mass or less, preferably 15% by mass or less, more preferably 10% by mass or less from the viewpoint of keeping the performance of the anodic oxide coating 2 high and reducing the cost.

The chemical conversion liquid preferably contains a non-aqueous solvent. The use of a chemical conversion solution containing a non-aqueous solvent has an advantage that it can be processed at a high throughput because the time required for the constant current conversion is shorter than that of an aqueous chemical conversion solution. In addition, when an aqueous solution is used as a chemical conversion solution, OH ions generated by water electrolysis etch the anodic oxide film to make it porous, so a main solvent having a low dielectric constant that can suppress water electrolysis is used. It is preferable to use it.

The type of the non-aqueous solvent is not particularly limited as long as it can be anodized satisfactorily and has sufficient solubility in a solute, but a solvent having one or more alcoholic hydroxyl groups and / or one or more phenolic hydroxyl groups, Or an aprotic organic solvent is preferable. Among these, a solvent having an alcoholic hydroxyl group is preferable from the viewpoint of storage stability.

Examples of the compound having an alcoholic hydroxyl group include monohydric alcohols such as methanol, ethanol, propanol, isopropanol, 1-butanol, 2-ethyl-1-hexanol and cyclohexanol; ethylene glycol, propylene glycol, butane-1,4 -Dihydric alcohols such as diol, diethylene glycol, triethylene glycol, and tetraethylene glycol; trihydric or higher polyhydric alcohols such as glycerin and pentaerythritol can be used. Moreover, the solvent which has functional groups other than alcoholic hydroxyl group in a molecule | numerator can also be used. Among these, those having two or more alcoholic hydroxyl groups are preferable in view of miscibility with water and vapor pressure, more preferably dihydric alcohols and trihydric alcohols, and particularly preferably ethylene glycol, propylene glycol, and diethylene glycol.

Examples of the compound having a phenolic hydroxyl group include unsubstituted phenol having one hydroxyl group, alkylphenols such as o- / m- / p-cresols and xylenols, and resorcinols having two hydroxyl groups. However, pyrogallol and the like can be used as those having three hydroxyl groups.

These compounds having an alcoholic hydroxyl group and / or a phenolic hydroxyl group may further have other functional groups in the molecule. For example, a solvent having an alkoxy group together with an alcoholic hydroxyl group such as methyl cellosolve and cellosolve can also be used.

As the aprotic organic solvent, either a polar solvent or a nonpolar solvent may be used.

The polar solvent is not particularly limited, and examples thereof include cyclic carboxylic acid esters such as γ-butyrolactone, γ-valerolactone, and δ-valerolactone; chain carboxylic acid esters such as methyl acetate, ethyl acetate, and methyl propionate. Cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate; chain carbonates such as dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, N-methylformamide, N-ethylformamide, N, N— Amides such as dimethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpyrrolidone, acetonitrile, glutaronitrile, adiponitrile, methoxya Tonitoriru, 3-methoxy nitriles such as propionitrile; trimethyl phosphate, phosphates such as triethyl phosphate.

The nonpolar solvent is not particularly limited, and examples thereof include hexane, toluene, and silicone oil.

These solvents may be used alone or in combination of two or more. Particularly preferable as the non-aqueous solvent of the chemical conversion liquid used for forming the anodic oxide coating 2 is ethylene glycol, propylene glycol, or diethylene glycol, which may be used alone or in combination. Moreover, if it contains the nonaqueous solvent, you may contain water.

The non-aqueous solvent is usually contained in an amount of 10% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, particularly preferably 55% by mass or more, and usually 95% by mass or less, based on the whole chemical conversion liquid. , Preferably 90% by mass or less, particularly preferably 85% by mass or less.

When the chemical conversion liquid contains water in addition to the non-aqueous solvent, the content thereof is usually 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 15% with respect to the whole chemical conversion liquid. The content is usually at least 85% by mass, preferably at most 50% by mass, particularly preferably at most 40% by mass.

The ratio of water to the non-aqueous solvent is preferably 1% by mass or more, preferably 5% by mass or more, more preferably 7% by mass or more, particularly preferably 10% by mass or more, and usually 90% by mass or less, preferably 60%. It is not more than mass%, more preferably not more than 50 mass%, particularly preferably not more than 40 mass%.

The chemical conversion liquid may contain other additives as necessary. For example, an additive for improving the film formability and film characteristics of the anodized film 2 may be contained. The additive is not particularly limited and may be used by adding one or more substances selected from known additives and other substances. At this time, there is no special restriction | limiting in the addition amount of an additive, What is necessary is just to consider an effect, cost, etc., and to make it an appropriate amount.

The electrolytic method for anodizing is not particularly limited. As the current waveform, for example, in addition to direct current, a pulse method in which an applied voltage is periodically interrupted, a PR method in which the polarity is inverted, other alternating current, AC / DC superimposition, incomplete rectification, modulation current such as a triangular wave, or the like can be used. However, preferably a direct current is used.

The method for controlling the current and voltage of anodic oxidation is not particularly limited, and conditions for forming an oxide film on the inner surface of the aluminum alloy container body 1 can be appropriately combined. Usually, it is preferable to anodize at a constant current and a constant voltage. In other words, it is preferable that the formation is performed at a constant current up to a predetermined formation voltage Vf, and after the formation voltage is reached, the voltage is held for a certain period of time to perform anodization.

At this time, in order to efficiently form an oxide film, the current density is usually 0.001 mA / cm ² or more, preferably 0.01 mA / cm ² or more. However, in order to obtain an oxide film with good surface flatness, the current density is usually 100 mA / cm ² or less, preferably 10 mA / cm ² or less.

Further, the formation voltage Vf is usually 3 V or more, preferably 10 V or more, more preferably 20 V or more. Since the obtained oxide film thickness is related to the formation voltage Vf, it is preferable to apply the voltage or more in order to give a certain thickness to the oxide film. However, it is usually 1000 V or less, preferably 700 V or less, more preferably 500 V or less. Since the obtained oxide film has high insulating properties, it is preferable to carry out at the voltage or lower in order to form a high-quality oxide film without causing high dielectric breakdown.

Note that it is also possible to use a method in which an alternating current having a constant peak current value is used in place of the direct current power source until the formation voltage is reached, and when the formation voltage is reached, the direct current voltage is switched to the direct current voltage and held for a certain time.

Other conditions for anodic oxidation are not particularly limited. However, the temperature at the time of anodization is set to a temperature range in which the chemical conversion liquid exists stably as a liquid. Usually, it is −20 ° C. or higher, preferably 5 ° C. or higher, more preferably 10 ° C. or higher. In consideration of production, energy efficiency, and the like at the time of anodization, it is preferable to perform the treatment at the temperature or higher. However, it is usually 150 ° C. or lower, preferably 100 ° C. or lower, more preferably 80 ° C. or lower. In order to maintain the composition of the chemical conversion solution and perform uniform anodic oxidation, the treatment is preferably performed at the temperature or lower.

The anodic oxidation includes a first step in which an inner surface of the aluminum alloy container body 1 and a counter electrode (for example, platinum) are disposed in the chemical conversion solution, and a plus is applied to the aluminum alloy container body 1 as the electrode. A second step of applying a negative current to pass a constant current for a predetermined time; and a third step of applying a constant voltage between the aluminum alloy container body 1 and the electrode for a predetermined time. Is preferred. The predetermined time of the second step is until the voltage between the aluminum alloy container body 1 and the predetermined electrode reaches a predetermined value (for example, 200 V when ethylene glycol is used). Preferably there is.

The predetermined time of the third step is preferably until the current between the aluminum alloy container body 1 and the predetermined electrode reaches a predetermined value, but the current value is the voltage described above. When it becomes, it decreases rapidly, and then gradually decreases with time. The smaller the residual current is, the better the quality of the oxide film is. However, for example, if a constant voltage treatment is performed for 24 hours, the film quality becomes equivalent to that obtained by heat treatment. In order to increase productivity, the constant voltage treatment may be stopped and heat treatment (annealing) may be performed at an appropriate time. The heat treatment is preferably performed at 150 ° C. or more and about 300 ° C. for 0.5 to 1 hour.

In the second step, a current of 0.01 to 100 mA, preferably 0.1 to 10 mA, more preferably 0.5 to 2 mA is applied per square centimeter.

As described above, in the third step, the voltage is set such that the chemical conversion liquid does not cause electrolysis. The thickness of the anodic oxide coating 2 depends on the voltage in the third step.

Although not bound by any theory, it is considered that the nonporous anodic oxide coating 2 formed during the chemical conversion treatment has an amorphous structure as a whole, and there are almost no grain boundaries such as crystals. . Further, by adding a compound having a buffering action or using a non-aqueous solvent as a solvent, a trace amount of carbon component is taken into the anodized film 2 and the bonding strength of Al—O is weakened. Thus, it is presumed that the amorphous structure of the entire film is stabilized.

The anodic oxide coating 2 manufactured as described above may be subjected to heat treatment for the purpose of removing moisture in the film. In particular, a metal oxide film mainly composed of high-purity aluminum that does not substantially contain the specific element has high thermal stability, and voids and gas reservoirs are not easily formed. For this reason, voids and seams are unlikely to enter the anodic oxide coating 2 even by annealing at about 300 ° C. or higher, and aluminum elution into the reaction solution due to generation of particles and exposure of aluminum can be suppressed. The heat treatment method is not particularly limited, but an annealing treatment in a heating furnace or the like is simple and preferable.

The temperature of the heat treatment is not particularly limited, but is usually 100 ° C. or higher, preferably 200 ° C. or higher, more preferably 250 ° C. or higher. In order to sufficiently remove moisture on the surface and inside of the metal oxide film by heat treatment, it is preferable to perform the treatment at the above temperature or more. However, it is usually 600 ° C. or lower, preferably 550 ° C. or lower, more preferably 500 ° C. or lower. In order to maintain the amorphous structure of the metal oxide film and maintain the flatness of the surface, it is preferable to perform the treatment at the temperature or lower. In the case of annealing treatment, the set temperature of the heating furnace is usually regarded as the heat treatment temperature.

The time for the heat treatment is not particularly limited, and may be appropriately set in consideration of surface roughness due to the heat treatment, productivity, etc., but is usually 1 minute or more, preferably 5 minutes or more, particularly preferably 15 minutes or more. is there. In order to sufficiently remove moisture on the surface and inside of the metal oxide film, it is preferable to perform the treatment for the above time or more. However, it is usually 180 minutes or less, preferably 120 minutes or less, more preferably 60 minutes or less. In order to maintain the metal oxide film structure and surface flatness, it is preferable to perform the treatment within the above time.

The gas atmosphere in the furnace during the annealing treatment is not particularly limited, but usually nitrogen, oxygen, or a mixed gas thereof can be appropriately used. Of these, an atmosphere having an oxygen concentration of 18 vol% or higher is preferable, a condition of 20 vol% or higher is more preferable, and a condition of oxygen concentration of 100 vol% is most preferable.

Next, a non-contaminating film 3 is provided on the anodic oxide film 2. The non-contaminating film 3 has a property that the contact angle with pure water on the surface is preferably 90 ° or more, more preferably 95 ° or more, and the polymer scale or the like is difficult to adhere. When the contact angle with pure water on the surface is less than 90 °, it is easy to get wet with the polymerization solvent, and a polymerization scale during the reaction is easily generated.

By providing such a non-contaminating coating 3 on the inner surface of the reaction vessel made of aluminum alloy, even if the polymer particles collide against the vessel wall at the time of stirring, it is difficult for them to adhere. The power is small. For this reason, it becomes difficult for polymer particles to aggregate, and generation | occurrence | production of a polymerization scale and a fine solidified material is reduced.

The non-contaminating film 3 is not particularly limited as long as it exhibits the above-mentioned non-contaminating property. For example, the non-contaminating film 3 is a film made of a polymer having a fluorine-containing aliphatic ring structure described in Patent Document 1, or a heat described in Patent Document 2. Examples thereof include a film made of an antifouling agent containing a compound having a dissociable fluorine-containing protecting group.

Although it is not limited at all, for example, a polymer having a fluorine-containing aliphatic ring structure is obtained by polymerizing a monomer having a fluorine-containing ring structure, or a fluorine-containing polymer having at least two polymerizable double bonds A polymer having a ring structure in the main chain obtained by cyclopolymerizing monomers is preferred.

The polymer having a ring structure in the main chain obtained by polymerizing a monomer having a fluorine-containing ring structure is, for example, a monomer having a fluorine-containing ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole). It can be obtained by homopolymerization or copolymerization with a radical polymerizable monomer such as tetrafluoroethylene.

Polymers having a ring structure in the main chain obtained by cyclopolymerization of a fluorine-containing monomer having at least two polymerizable double bonds are, for example, perfluoro (allyl vinyl ether), perfluoro (butenyl vinyl ether), etc. It is obtained by copolymerization with a radically polymerizable monomer such as tetrafluoroethylene.

Further, a monomer having a fluorine-containing ring structure such as perfluoro (2,2-dimethyl-1,3-dioxole) and at least two polymerizable double molecules such as perfluoro (allyl vinyl ether) and perfluoro (butenyl vinyl ether). A polymer obtained by copolymerizing a fluorine-containing monomer having a bond may also be used.

The polymer having a fluorine-containing aliphatic ring structure is preferably a polymer having a ring structure in the main chain, but a polymer containing 20% or more of the ring structure is preferable from the viewpoints of transparency and mechanical properties.

Although there is no particular limitation on the method of providing the non-staining coating 3 by coating the polymer having a fluorine-containing aliphatic ring structure on the anodic oxide coating 2, a commonly used coating or laminating method is appropriately used. Can do. For example, it is possible to apply the polymer solution after drying the solvent, or to coat the polymer film by laminating in a usual manner.

Stain-proofing agent comprising a compound having a dissociative fluorinated protecting group, for example, formula (I): Z-X- O-R f (I)
(Wherein Z is an organic group having or not having a functional group, X is C═O or SO ₂ , R _f is a hydrogen atom partially or entirely substituted with a fluorine atom, and an oxygen atom It is an organic group which may contain a compound having a thermally dissociable fluorine-containing protecting group.

Here, —R _f in the above formula (I) is preferably represented by the following formula (II) or (III).

In the formula, R ¹ , R ² and R ³ are the same or different and each is a hydrogen atom or an organic group having 1 to 18 carbon atoms and optionally containing a fluorine atom, R ⁴ is a hydrogen atom having 1 to 18 carbon atoms Is an organic group partially or entirely substituted with a fluorine atom.

In the formula, R ¹ , R ² , R ³ , R ⁴ and R ⁵ are the same or different, and any of them may be a hydrogen atom or 1 to 18 carbon atoms, and a part or all of the hydrogen atoms may be substituted with fluorine atoms. It is a good organic group, and at least one of R ¹ , R ² , R ³ , R ⁴ and R ⁵ is a fluorine atom-containing group.

The non-contaminating film 3 may be obtained by applying the above-mentioned anti-contamination agent on the anodized film 2, and the anti-contamination agent, the crosslinking functional group-containing coating resin, the curing agent and / or the curing. A coating composition comprising a catalyst may be obtained, and this may be applied onto the anodized film 2 to obtain the non-contaminating film 3.

The crosslinkable functional group-containing coating resin may be, for example, a solvent-soluble fluorine coating resin containing a hydroxyl group and / or a carboxyl group, or may be an acrylic silicon coating resin having an alkoxysilyl group.

The thickness of the non-contaminating film 3 is not particularly limited, but is preferably about 0.1 to 200 μm, more preferably about 0.5 to 100 μm.

As described above, the aluminum alloy reaction vessel 10 according to the present invention has the anodized film 2 and the non-contaminating film 3 formed in this order on the inner surface of the aluminum alloy container main body 1. In addition, for example, a stirring blade may be provided, and a heating mechanism, a cooling mechanism, a raw material supply port, a product outlet, and the like may be provided. In addition, a contaminated film may be formed on the stirring blade in the same manner as the container.

Since the aluminum alloy reaction vessel 10 of the present invention is mainly composed of an aluminum alloy, it has high thermal conductivity and can efficiently remove reaction heat. In addition, since the non-contaminating film 3 is formed on the inner surface of the container, it can be operated for a long time with little adhesion of polymerization scale and generation of fine solidified products during the reaction. Furthermore, since the surface of the aluminum alloy container main body 1 is provided with an anodic oxide coating 2 and is passivated, elution of aluminum from the main body 1 is prevented, and aggregation of polymer particles caused by the eluted aluminum is also prevented. Reduced.

Therefore, the reaction vessel 10 of the present invention is used for various reactions, and is particularly preferably used for a reaction in which a monomer is polymerized to obtain a polymer, particularly a polymer particle, specifically, a binder for an electrochemical device. It is done. Furthermore, since the container 10 of the present invention hardly adheres to the polymer particles on the wall surface of the container, the container 10 can be used as a mixing container for preparing a slurry for electrode formation, for example, using an electrochemical element binder. .

Examples of the monomer used for the polymerization include various monomers that have been used in the production of binders for electrochemical devices, such as aliphatic conjugated diene monomers and ethylenically unsaturated carboxylic acid monomers. And ethylenically unsaturated carboxylic acid ester monomers, alkenyl aromatic monomers, vinyl cyanide monomers, unsaturated carboxylic acid amide monomers, and the like. These monomers can be used individually by 1 type or in combination of 2 or more types, There is no limitation in the composition.

Specific examples of the aliphatic conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene. Examples thereof include butadiene and 1,3-pentadiene.

Specific examples of the ethylenically unsaturated carboxylic acid monomer include monovalent carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; polyvalent carboxylic acids such as maleic acid, fumaric acid, and itaconic acid; or monoethyl maleate, And partial esters of polycarboxylic acids such as monobutyl fumarate. Specific examples of the ethylenically unsaturated carboxylic acid ester monomer include acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate and 2-ethylhexyl acrylate; methacrylic acid esters such as methyl methacrylate and ethyl methacrylate; dimethyl fumarate, And polyvalent carboxylic acid esters such as diethyl fumarate, dimethyl maleate, diethyl maleate and dimethyl itaconate. These esters are not limited to alkyl esters, such as glycidyl acrylate, glycidyl methacrylate, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate. , Di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate, aminoethyl acrylate, aminoethyl methacrylate, dimethyl Aminoethyl acrylate, dimethylaminoethyl methacrylate, diethylamino Ethyl acrylate, as diethylaminoethyl methacrylate, glycidyl group, hydroxyl group, may have a functional group such as amino groups.

Specific examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, vinyltoluene and the like.

Specific examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and α-ethylacrylonitrile.

Specific examples of the unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N-dimethylacrylamide and the like.

Further, as the monomer, another monomer copolymerizable with the above monomer may be contained. Examples of such other monomers include aliphatic vinyl ester monomers such as vinyl acetate and vinyl propionate; methyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, Vinyl ether monomers such as t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; basic monomers such as 2-vinyl pyridine and 4-vinyl pyridine; ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamide -Sulphonic acid group-containing monomers such as 2-methylpropanesulfonic acid; Vinylsilane monomers such as vinyltrimethoxysilane; 3-acrylamidopropyltrimethylammonium chloride, 3-methacrylamidopropyltrimethylammo It can also be used for (co) polymerization of such monomer having a quaternary ammonium group such as Umukuroraido.

Furthermore, in addition to the above, a crosslinkable monomer such as divinylbenzene, ethylene glycol dimethacrylate, or trimethylolpropane triacrylate can be used in combination as the monomer.

In the present invention, from the viewpoint of obtaining polymer particles used as a binder for an electrochemical element, it is preferable to emulsion polymerize the monomer. For this reason, at least a part of the monomer is added to the reaction vessel in the form of an emulsion. Hereinafter, although emulsion polymerization is taken as an example and described in more detail, the polymerization form in the present invention is not limited to emulsion polymerization. The monomer emulsion in the following is adjusted when emulsion polymerization is carried out, but when taking a polymerization form other than emulsion polymerization, the monomer may be supplied to the reaction vessel in a form other than the emulsion. .

The composition of the monomer emulsion may be unchanged from the start point to the end point of the polymerization or may be changed over time as the polymerization progresses. The change in the composition of the monomer emulsion may be continuous or discontinuous. In order to change the composition of the monomer emulsion, the monomer may be supplied to a container for preparing the monomer emulsion at any time. To prepare the monomer emulsion, two or more A so-called power feed method may be employed using a container.

In the present invention, the emulsifier used for preparing the monomer emulsion is not particularly limited as long as it is conventionally used in emulsion polymerization. As the emulsifier, a water-soluble polymer protective colloid can be used in addition to the surfactant. Further, an alkali-soluble resin as described in, for example, JP-A-3-269032 can also be used.

Examples of surfactants include anionic surfactants such as sulfate esters of higher alcohols, alkylbenzene sulfonates, aliphatic sulfonates, aliphatic carboxylates, sulfate esters of nonionic surfactants; polyethylene glycol Nonionic surfactants such as alkyl ester type, alkylphenyl ether type, and alkyl ether type are used singly or in combination. Cationic surfactants and amphoteric surfactants can also be used.

Water-soluble polymer protective colloids include polyvinyl alcohol and various modified products; polyacrylic acid or polymethacrylic acid and salts thereof; polyvinyl alkyl ethers; copolymers of vinyl acetate and acrylic acid, methacrylic acid or maleic anhydride, and These saponified products; lower alkyl vinyl ether-maleic anhydride copolymer; cellulose derivatives such as alkyl cellulose, hydroxyalkyl cellulose, alkyl hydroxyalkyl cellulose, and carboxymethyl cellulose; starch derivatives such as alkyl starch, carboxymethyl starch, and oxidized starch; Examples thereof include rubber, tragacanth rubber; polyalkylene glycol and the like.

The amount of the emulsifier used for preparing the monomer emulsion is not particularly limited, and is usually 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the monomer. is there.

All monomers used for the emulsion polymerization may be supplied as a monomer emulsion, and a part of the monomer is charged into the reaction vessel separately from the monomer emulsion, The body may be supplied as a monomer emulsion. It is preferable to supply all monomers as a monomer emulsion. The start time of the supply of the monomer emulsion is not particularly limited. For example, the polymerization may be started after a part or all of the monomer emulsion is supplied to the reaction vessel, or the monomer is charged into the reaction vessel separately from the monomer emulsion. You may start supply of a monomer emulsion after starting. In these cases, the ratio of the amount of monomer charged into the reaction vessel in advance and the amount of monomer supplied to the reaction vessel later is not particularly limited.

Thus, at the time of polymerization, all of the polymerizable monomer may be added to the reaction vessel in the form of an emulsion, and after the entire amount of the polymerizable monomer is supplied to the reaction vessel, the polymerization is started. May be. Furthermore, after a part of the polymerizable monomer is supplied to the reaction vessel, the polymerization may be started, and the remaining polymerizable monomer may be sequentially supplied to the reaction vessel to carry out the polymerization.

Furthermore, it is also possible to decompose the polymerization initiator in the reaction vessel in a state where no monomer is present in the reaction vessel, and to supply the monomer emulsion to this.

It is also possible to cause the latex for seed to exist in the reaction vessel, and to carry out the polymerization by supplying a monomer emulsion to this. Thereby, it is possible to control the particle size of the obtained polymer latex.

What are the monomer composition in the monomer emulsion and the monomer composition in the reaction container and the monomer composition of the latex for seeding when polymerizing a part of the monomer in the reaction container in advance? , Not necessarily the same, but can be different as desired.

The supply of the monomer emulsion to the reaction vessel may be continuous or intermittent. There is no particular limitation on the supply start and end times. Further, the supply speed (supply amount per unit time) may be uniform or non-uniform. Further, the time required for supply is not limited.

Usually, the polymerization is carried out using a polymerization initiator. Any polymerization initiator may be used as long as it is conventionally used in emulsion polymerization, and the amount used is not particularly limited. Specific examples of the polymerization initiator include water-soluble polymerization initiators such as potassium persulfate, ammonium persulfate, sodium persulfate, hydrogen peroxide, and t-butyl hydroperoxide; azobisisobutyronitrile, 2,2-azobis Oil-soluble polymerization initiators such as -2,4-dimethylvaleronitrile, benzoyl peroxide, and di-t-butyl peroxide can be used. Preferably, a water-soluble polymerization initiator is used. Further, these polymerization initiators can be used as a redox polymerization initiator in combination with a reducing agent.

In a preferred embodiment, these polymerization initiators are charged into a reaction vessel at the start of polymerization. This is different from microsuspension polymerization (microsuspension polymerization) in which a polymerization initiator is formed into microdroplets together with a monomer and a dispersant. Adding a polymerization initiator into a container for preparing a monomer emulsified liquid and emulsifying with the monomer may start polymerization due to heat of stirring or the like, which is problematic in terms of safety. In addition, a polymerization initiator may be added all at once, and the method of adding continuously or dividing according to progress of superposition | polymerization can also be taken.

In addition to the preparation of the monomer emulsion, an emulsifier can be used as necessary. The amount used is not particularly limited. As an example of such use, a mode in which the monomer is added in advance to the reaction vessel before supplying the monomer, a part of the monomer is polymerized in the reaction vessel and then the monomer emulsion is supplied to the reaction vessel. When starting, the aspect used as the emulsifier of the one part monomer, the aspect which adds an emulsifier separately in parallel with supply of a monomer emulsion, etc. can be shown.

Examples of the emulsifier used for purposes other than the preparation of the monomer emulsion include those similar to those used for the preparation of the monomer emulsion.

Moreover, various chain transfer agents can be used during the polymerization. The amount of the chain transfer agent used is not particularly limited, but is usually 0 to 10 parts by mass with respect to 100 parts by mass of the monomer. The chain transfer agent may be added directly to the reaction vessel or may be added as an emulsion together with the monomer. The type of chain transfer agent is not particularly limited, and specific examples thereof include n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexadecyl mercaptan, n-tetradecyl mercaptan, 2,2,4 Mercaptan compounds such as 1,6,6-pentamethylheptane-4-thiol and 2,4,6-trimethylnonane-4-thiol; Halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; Dimethylxanthogen disulfide, diethyl Xanthogen compounds such as xanthogen disulfide and diisopropylxanthogen disulfide; thiuram compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetrabutylthiuram disulfide; thioglycolic acid, octyl thioglycolate Thioglycolic acid compounds such as 2-ethylhexyl thioglycolate; α-methylstyrene dimers such as 2,4-diphenyl-4-methyl-1-pentene; terpinolene, α-terpinene, β-terpinene, γ-terpinene, dipentene, etc. Terpene compounds; phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol; allyl compounds such as acrolein, methacrolein and allyl alcohol; α-benzyloxystyrene, α-benzyloxy And vinyl ether compounds such as acrylonitrile and α-benzyloxyacrylamide; aldehydes such as benzaldehyde; polycyclic aromatic hydrocarbons such as triphenylmethane and pentaphenylethane; 2,5-dihydrofuran and the like. These chain transfer agents can be used singly or in combination of two or more.

In emulsion polymerization, other commonly used additives such as electrolytes (sodium pyrophosphate, sodium polyacrylate, sodium hexametaphosphate, etc.), antifoaming agents (polyglycol, fatty acid ester, phosphate ester, silicone oil) Etc.), polymerization accelerators, chelating agents, and the like can be used. A polymerization retarder can also be used for the purpose of controlling the reaction rate. Specific examples thereof include 2,4-dinitrochlorobenzene. There is no restriction | limiting in particular about the addition method of the said additive component, Any of a batch addition method, a division | segmentation addition method, and a continuous addition method can be employ | adopted.

The polymer particles obtained by the polymerization as described above are preferably used as a binder for an electrochemical element, and particularly preferably used as a binder for a lithium ion secondary battery electrode.

An electrode for a secondary battery such as a lithium ion secondary battery has an electrode mixture layer containing a binder and an electrode active material attached to a current collector. Here, the binder obtained by the above polymerization is used as the binder, and the electrode active material may be any material that can reversibly insert and release lithium ions by applying a potential in the electrolyte. Organic compounds can also be used.

Electrode active materials (positive electrode active materials) for lithium ion secondary battery positive electrodes are broadly classified into those made of inorganic compounds and those made of organic compounds. Examples of the positive electrode active material made of an inorganic compound include transition metal oxides, composite oxides of lithium and transition metals, and transition metal sulfides. As the transition metal, Fe, Co, Ni, Mn and the like are used. Specific examples of the inorganic compound used for the positive electrode active material include LiCoO ₂ , LiNiO ₂ , LiMnO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , LiFeVO ₄ and other lithium-containing composite metal oxides; TIS ₂ , TIS ₃ , non- Transition metal sulfides such as crystalline MoS ₂ ; transition metal oxides such as Cu ₂ V ₂ O ₃ , amorphous V ₂ O—P ₂ O ₅ , MoO ₃ , V ₂ O ₅ , V ₆ O ₁₃ It is done. These compounds may be partially element-substituted. As the positive electrode active material made of an organic compound, for example, a conductive polymer such as polyacetylene or poly-p-phenylene can be used. An iron-based oxide having poor electrical conductivity may be used as an electrode active material covered with a carbon material by allowing a carbon source material to be present during reduction firing. These compounds may be partially element-substituted.

The positive electrode active material for a lithium ion secondary battery may be a mixture of the above inorganic compound and organic compound. The particle diameter of the positive electrode active material is appropriately selected in consideration of other constituent elements of the battery. From the viewpoint of improving battery characteristics such as load characteristics and cycle characteristics, the 50% volume cumulative diameter is usually 0.1. It is ˜50 μm, preferably 1 to 20 μm. When the 50% volume cumulative diameter is within this range, a secondary battery having a large charge / discharge capacity can be obtained, and handling of the slurry for electrodes and the electrodes is easy. The 50% volume cumulative diameter can be determined by measuring the particle size distribution by laser diffraction.

Examples of electrode active materials (negative electrode active materials) for negative electrodes of lithium ion secondary batteries include carbonaceous materials such as amorphous carbon, graphite, natural graphite, mesocarbon microbeads, pitch-based carbon fibers, and high conductivity such as polyacene. Examples include molecules. In addition, as the negative electrode active material, metals such as silicon, tin, zinc, manganese, iron, nickel, alloys thereof, oxides or sulfates of the metals or alloys are used. In addition, lithium alloys such as lithium metal, Li—Al, Li—Bi—Cd, and Li—Sn—Cd, lithium transition metal nitride, silicon, and the like can be used. As the electrode active material, a material obtained by attaching a conductivity imparting material to the surface by a mechanical modification method can be used. The particle diameter of the negative electrode active material is appropriately selected in consideration of other constituent elements of the battery. From the viewpoint of improving battery characteristics such as initial efficiency, load characteristics, and cycle characteristics, a 50% volume cumulative diameter is usually The thickness is 1 to 50 μm, preferably 15 to 30 μm.

The electrode mixture layer may contain a conductivity imparting material or a reinforcing material. As the conductivity-imparting material, conductive carbon such as acetylene black, ketjen black, carbon black, graphite, vapor-grown carbon fiber, and carbon nanotube can be used. Examples thereof include carbon powders such as graphite, and fibers and foils of various metals. As the reinforcing material, various inorganic and organic spherical, plate-like, rod-like or fibrous fillers can be used. By using the conductivity imparting material, the electrical contact between the electrode active materials can be improved, and the discharge rate characteristics can be improved when used in a lithium ion secondary battery. The amount of the conductivity-imparting material used is usually 0 to 20 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the electrode active material.

The electrode mixture layer can be formed by adhering an electrode-forming slurry containing a binder, an electrode active material and a solvent (hereinafter sometimes referred to as “mixture slurry”) to a current collector.

Any solvent may be used as long as it can dissolve or disperse the binder into particles. When a solvent that dissolves the binder is used, the dispersion of the electrode active material and the like is stabilized by the adsorption of the binder to the surface.

The mixture slurry contains a solvent and can be obtained by dispersing optional components such as an electrode active material, an essential component of a binder, and a conductivity-imparting material.

As a solvent used for the mixture slurry, either water or an organic solvent can be used. Examples of organic solvents include cycloaliphatic hydrocarbons such as cyclopentane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; ketones such as ethyl methyl ketone and cyclohexanone; ethyl acetate, butyl acetate, γ-butyrolactone, ε -Esters such as caprolactone; Acylonitriles such as acetonitrile and propionitrile; Ethers such as tetrahydrofuran and ethylene glycol diethyl ether; Alcohols such as methanol, ethanol, isopropanol, ethylene glycol and ethylene glycol monomethyl ether; N-methyl Amides such as pyrrolidone and N, N-dimethylformamide are exemplified. These solvents may be used alone or in admixture of two or more and appropriately selected from the viewpoint of drying speed and environment.

The mixture slurry may further contain additives that exhibit various functions such as a thickener. Examples of thickeners include, for example, cellulosic polymers such as carboxymethyl cellulose, methyl cellulose, hydroxypropyl cellulose, and ammonium and alkali metal salts thereof; modified or unmodified poly (meth) acrylic acid, and ammonium thereof. Salts and alkali metal salts; polyvinyl alcohols such as modified or unmodified polyvinyl alcohol, copolymers of acrylic acid or acrylates and vinyl alcohol, maleic anhydride, maleic acid or copolymers of fumaric acid and vinyl alcohol Polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, modified polyacrylic acid, oxidized starch, phosphate starch, casein, various modified starches, acrylonitrile-butadiene copolymer hydride, etc. That.

In addition to the above components, the mixture slurry contains trifluoropropylene carbonate, vinylene carbonate, catechol carbonate, 1,6-dioxaspiro [4,4] nonane-2,7 in order to increase the stability and life of the battery. -Dione, 12-crown-4-ether and the like can be used. These may be used by being contained in an electrolyte solution described later.

The amount of the solvent in the mixture slurry is adjusted so as to have a viscosity suitable for coating depending on the type of the electrode active material, the binder and the like. Specifically, the solid concentration of the mixture slurry in the mixture slurry is preferably 30 to 90% by mass, and more preferably 40 to 80% by mass. Used by adjusting.

The mixture slurry is obtained by mixing an electrode active material, a binder, a conductivity-imparting material added as necessary, other additives, and a solvent using a mixer. Mixing may be performed by supplying the above components all at once to a mixer (preferably the reaction vessel of the present invention). When using an electrode active material, binder, conductivity-imparting material, and thickener as components of the mixture slurry, mix the conductivity-imparting material and thickener in a solvent to disperse the conductive material in the form of fine particles. Then, it is preferable to add a binder and an electrode active material and then mix them, because the dispersibility of the slurry is improved. As a mixer, a ball mill, a sand mill, a pigment disperser, a pulverizer, an ultrasonic disperser, a homogenizer, a planetary mixer, a Hobart mixer, and the like can be used. It is preferable because aggregation of the resin can be suppressed.

The particle size of the mixture slurry is preferably 35 μm or less, and more preferably 25 μm or less. When the particle size of the slurry is in the above range, the conductive material is highly dispersible and a homogeneous electrode can be obtained.

The current collector is not particularly limited as long as it is an electrically conductive and electrochemically durable material. From the viewpoint of having heat resistance, for example, iron, copper, aluminum, nickel, stainless steel, etc. Metal materials such as titanium, tantalum, gold, and platinum are preferable. Among these, aluminum is particularly preferable for the positive electrode of the lithium ion secondary battery, and copper is particularly preferable for the negative electrode. The shape of the current collector is not particularly limited, but a sheet shape having a thickness of about 0.001 to 0.5 mm is preferable. In order to increase the adhesive strength of the electrode mixture layer, the current collector is preferably used after being roughened. Examples of the roughening method include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method. In the mechanical polishing method, an abrasive cloth paper with a fixed abrasive particle, a grindstone, an emery buff, a wire brush provided with a steel wire or the like is used. Further, an intermediate layer may be formed on the current collector surface in order to increase the adhesive strength and conductivity of the electrode mixture layer.

The method for producing the electrode mixture layer may be any method in which the electrode mixture layer is bound in layers on at least one side, preferably both sides of the current collector. For example, the mixture slurry is applied to a current collector and dried, and then heated at 120 ° C. or higher for 1 hour or longer to form an electrode mixture layer. The method for applying the mixture slurry to the current collector is not particularly limited. Examples thereof include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, and a brush coating method. Examples of the drying method include drying by warm air, hot air, low-humidity air, vacuum drying, and drying by irradiation with (far) infrared rays or electron beams.

Next, it is preferable to lower the porosity of the electrode mixture layer by pressure treatment using a mold press or a roll press. The preferable range of the porosity of the electrode mixture layer is 5% to 15%, more preferably 7% to 13%. If the porosity is too high, charging efficiency and discharging efficiency are deteriorated. On the other hand, when the porosity is too low, there is a problem that it is difficult to obtain a high volume capacity, or the electrode mixture layer is easily peeled off and a defect is likely to occur. Further, when a curable polymer is used as the binder, it is preferably cured.

The thickness of the electrode mixture layer is usually 5 to 300 μm, preferably 10 to 250 μm, for both the positive electrode and the negative electrode.

(Example)
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto. In addition, unless otherwise indicated, the part and% in a present Example are a mass reference | standard.

In Examples and Comparative Examples, the amount of polymerization scale, the amount of fine solidified matter, and charge / discharge cycle characteristics were evaluated as follows.

[Temperature rise during reaction]
Using a thermometer attached to the reaction vessel, the internal temperature of the reaction vessel was measured continuously from the start of polymerization to the end of polymerization (before cooling), and the temperature deviation from the set temperature was confirmed.

[Amount of polymerization scale]
After completion of the polymerization reaction, the polymerization scale attached to the reaction vessel wall and the stirring blade is collected, and the mass after the drying (polymerization scale amount) is measured. The ratio of the polymerization scale amount to the total mass of the monomers used for the polymerization is expressed as a percentage.

[Amount of fine solidified product]
The copolymer latex (weight: W2) having a solid content of 45%, which has been precisely weighed, is filtered through a 325 mesh wire mesh, the coagulum remaining on the wire mesh is dried in an infrared oven for 20 minutes, and the weight (W3) is precisely weighed. To do. The ratio of W3 to W2 was expressed as a percentage.

[Charge / discharge cycle characteristics]
Using the secondary batteries obtained in the examples and comparative examples, charging was performed at a constant current until the voltage reached 4.2 V by a constant current constant voltage charging method of 0.1 C at 25 ° C., and then charged at a constant voltage. Moreover, the charge / discharge cycle which discharges to 3.0V with a constant current of 0.1 C was performed. The charge / discharge cycle was performed up to 100 cycles, and the ratio of the discharge capacity at the 50th cycle to the initial discharge capacity was taken as the capacity maintenance rate, and the determination was made based on the number of batteries generated with this capacity maintenance rate of 80% or less. The discharge capacity at the 50th cycle was defined as the battery capacity, and the test was performed with 50 batteries each manufactured. It shows that it is excellent in charging / discharging cycling characteristics, so that this number is small.

Example 1
(Create reaction vessel)

<Creation of container body>
A cylindrical container body was prepared by bending and arc welding a plate (3 mm thick) of aluminum alloy A5083.

<Formation of anodized film>
After dissolving 1.8 parts of tartaric acid in 39.5 parts of water, 158 parts of ethylene glycol (EG) was added and mixed with stirring.
While this solution was stirred, 29% aqueous ammonia was added until the pH of the solution reached 7.1 to prepare a chemical conversion solution a.
In this chemical conversion solution, the container body was formed at a constant current of 1 mA / cm ² up to a chemical conversion voltage of 50V. After reaching 50V, the container body was maintained at a constant voltage for 30 minutes for anodization.
After the reaction, the product was sufficiently washed with pure water and then dried at room temperature. The obtained aluminum sample piece with an oxide film was annealed in an IR furnace at 300 ° C. for 1 hour, then opened to the atmosphere and left at room temperature for 48 hours. The thickness of the nonporous metal oxide film was measured and found to be 0.08 μm.

<Formation of non-contaminating film>
The surface of the anodized film is degreased with an organic solvent, and PES primer 462-Z-68501 manufactured by DuPont is spray-coated so that the thickness after firing is 8 μm, and dried at 100 ° C. for 10 minutes. On top of this, PFA paint AD-2CR manufactured by Daikin Industries, Ltd. was spray-coated to a thickness of 25 μm after firing, and baked at 380 ° C. for 20 minutes to form a non-staining film.

Thus, an aluminum alloy reaction vessel of the present invention was obtained.
Separately from the above, a glass five-hole separable cover was prepared as a reaction vessel lid, and a cooling device, a thermometer, and a stirring blade were attached thereto to constitute a reaction apparatus.

(Manufacture of polymer)
In an emulsification tank equipped with a stirrer, 50 parts of water, 31 parts of butadiene, 32 parts of styrene, 10.5 parts of methyl methacrylate, 6 parts of acrylonitrile, 0.5 part of acrylic acid, 0.6 part of t-dodecyl mercaptan and dodecylbenzenesulfone 0.3 parts of sodium acid salt was added and stirred to obtain a monomer emulsion.

Separately from the preparation of the monomer emulsion, 70 parts of water, 4 parts of butadiene, 7 parts of styrene, 4 parts of methyl methacrylate, 2 parts of acrylonitrile, in a prepared aluminum alloy reaction vessel (internal volume 3 liters), 2 parts of itaconic acid, 1 part of acrylic acid, 0.3 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate and 0.6 part of n-dodecyl mercaptan were added and reacted at 70 ° C. for 2 hours.

Subsequently, the monomer emulsion prepared above was continuously supplied to the reaction apparatus over 5 hours for polymerization. In order to complete the polymerization, the reaction was further continued for 4 hours after the completion of the supply of the monomer emulsion to obtain a copolymer latex having a polymerization conversion rate of 98%. After cooling, the pH was adjusted to 8.5 using 5% sodium hydroxide. A copolymer latex having a solid content concentration of 45.2% and a viscosity of 80 mPa · s was obtained. The amount of polymerization scale was 0.0003%, and the amount of fine solidified product was 0.0015%.

(Example 2)
In an emulsification tank equipped with a stirrer, 30 parts of water, 35 parts of butadiene, 39 parts of styrene, 14.5 parts of methyl methacrylate, 8 parts of acrylonitrile, 0.5 part of acrylic acid, 0.6 part of t-dodecyl mercaptan and dodecylbenzenesulfone 0.3 parts of sodium acid salt was added and stirred to obtain a monomer emulsion.

Separately from the preparation of the monomer emulsion, 70 parts of water, 0.3 part of sodium dodecylbenzenesulfonate, 2 parts of itaconic acid are contained in the reaction vessel made of aluminum alloy (internal volume 3 liters) prepared in Example 1. Parts, 1 part of acrylic acid and 5.5 parts of styrene-acrylic acid copolymer latex (average particle size 0.05 microns) were charged and the temperature was raised to 70 ° C. Next, 1 part of potassium persulfate was added to initiate the polymerization. Subsequently, the monomer emulsion prepared above was continuously supplied to the reactor over 5 hours to perform polymerization. In order to complete the polymerization, the reaction was further continued for 4 hours after the completion of the monomer emulsion supply to obtain a copolymer latex having a polymerization conversion rate of 98%. After cooling, the pH was adjusted to 8.5 using 5% sodium hydroxide. A copolymer latex having a solid content concentration of 50.5% and a viscosity of 120 mPa · s was obtained. The amount of polymerization scale was 0.0004%, and the amount of fine coagulum was 0.0018%.

(Comparative Example 1)
In the production of the reaction container of Example 1, an aluminum alloy reaction container was produced in the same manner as in Example 1 except that the non-contaminating film was formed directly on the container body without forming the anodized film. .

A polymerization reaction was performed in the same manner as in Example 1 except that the obtained reaction vessel was used. A copolymer latex having a polymerization conversion of 98%, a solid content concentration of 45.1% and a viscosity of 80 mPa · s was obtained. The pH of the copolymer latex was adjusted to 8.5 using 5% sodium hydroxide. The amount of polymerization scale was 0.0005%, and the amount of fine coagulum was 1.5%. The inner surface after the polymerization reaction was discolored.

(Comparative Example 2)
In the production of the reaction vessel of Example 1, an aluminum alloy reaction vessel was produced in the same manner as in Example 1 except that the non-contaminating film was not formed after the formation of the anodized film.

The polymerization reaction was performed in the same manner as in Example 1 except that the obtained reaction vessel was used. A copolymer latex having a polymerization conversion rate of 95%, a solid content concentration of 44.3%, and a viscosity of 80 mPa · s was obtained. The pH of the copolymer latex was adjusted to 8.5 using 5% sodium hydroxide. The amount of polymerization scale was 0.5%, and the amount of fine coagulum was 0.20%.

(Comparative Example 3)
In the production of the reaction vessel of Example 1, a cylindrical vessel body was produced by bending and arc welding using a SUS electrolytic polishing plate (3 mm thick) instead of the plate of aluminum alloy A5083. A SUS reaction vessel was prepared in the same manner as in Example 1 except that this vessel body was used.

A polymerization reaction was carried out in the same manner as in Example 1 except that the obtained reaction vessel was used. A copolymer latex having a polymerization conversion of 98%, a solid content concentration of 44.8% and a viscosity of 80 mPa · s was obtained. The pH of the copolymer latex was adjusted to 8.5 using 5% sodium hydroxide. The amount of polymerization scale was 0.0005%, and the amount of fine coagulum was 0.0025%, which was as good as in the examples. However, since the heat conduction in the SUS reaction vessel is low, the removal efficiency of the polymerization reaction heat is high. Unfortunately, the temperature during the reaction increased as a result.
The above results are summarized in the table below.

(Example 3)
(Production of slurry composition for secondary battery negative electrode)
Carboxymethylcellulose (CMC, “BSH-12” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was prepared as a thickener. The polymerization degree of the thickener was 1700, and the etherification degree was 0.65.

To the reaction vessel prepared in Example 1, 100 parts of artificial graphite (average particle size: 24.5 μm) as a negative electrode active material and 1 part of a 1% aqueous solution of the above thickener were added, respectively, and the solid content concentration in ion-exchanged water After adjusting to 55%, the mixture was mixed at 25 ° C. for 60 minutes. Next, after adjusting the solid content concentration to 52% with ion-exchanged water, the mixture was further mixed at 25 ° C. for 15 minutes to obtain a mixed solution.

In the above mixed solution, 1 part of the copolymer latex prepared in Example 1 (based on solid content) and ion-exchanged water were added, adjusted to a final solid content concentration of 42%, and further mixed for 10 minutes. This was defoamed under reduced pressure to obtain a slurry composition for a secondary battery negative electrode having good fluidity.

(Manufacture of batteries)
The slurry composition for secondary battery negative electrode was applied on a copper foil having a thickness of 20 μm with a comma coater so that the film thickness after drying was about 200 μm, and dried for 2 minutes (0.5 m / min). Speed, 60 ° C.), and further heat-treated (120 ° C.) for 2 minutes to obtain an electrode raw material. This raw electrode was rolled with a roll press to obtain a secondary battery negative electrode having a negative electrode active material layer thickness of 80 μm.

The negative electrode is cut into a disk shape having a diameter of 15 mm, and a separator made of a disk-shaped porous polypropylene film having a diameter of 18 mm and a thickness of 25 μm, a metal lithium used as the positive electrode, and an expanded metal are sequentially laminated on the negative electrode active material layer surface side. This was stored in a stainless steel coin-type outer container (diameter 20 mm, height 1.8 mm, stainless steel thickness 0.25 mm) provided with polypropylene packing. The electrolyte is poured into the container so that no air remains, and the outer container is fixed with a 0.2 mm thick stainless steel cap through a polypropylene packing, and the battery can is sealed, and the diameter is A half cell (secondary battery) having a thickness of 20 mm and a thickness of about 2 mm was produced.

In addition, as an electrolytic solution, LiPF ₆ was added at 1 mol / liter in a mixed solvent obtained by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) at EC: DEC = 1: 2 (volume ratio at 20 ° C.). A solution dissolved at a concentration was used. The evaluation results of the charge / discharge cycle characteristics of this half cell are shown in Table 2.

(Comparative Example 4)
A half cell was prepared in the same manner as in Example 3 except that the reaction container and copolymer latex prepared in Comparative Example 1 were used as the reaction container and polymer latex used in the preparation of the slurry composition. The results are shown in Table 2.

(Comparative Example 5)
A half cell was prepared in the same manner as in Example 3 except that the reaction container and copolymer latex prepared in Comparative Example 2 were used as the reaction container and polymer latex used in the preparation of the slurry composition. The results are shown in Table 2.

(Comparative Example 6)
A half cell was prepared in the same manner as in Example 3 except that the reaction container and copolymer latex prepared in Comparative Example 3 were used as the reaction container and polymer latex used in the preparation of the slurry composition. The results are shown in Table 2.

DESCRIPTION OF SYMBOLS 1 ... Aluminum alloy main body 2 ... Anodized film 3 ... Non-contaminating film 10 ... Aluminum alloy reaction vessel

Claims

An aluminum alloy reaction vessel in which an anodized film and a non-contaminating film are formed in this order on the inner surface.
The reaction vessel made of aluminum alloy according to claim 1, wherein the anodized film is a nonporous anodized film.
The aluminum alloy reaction vessel according to claim 1, wherein the anodized film is a non-porous anodized film anodized using a non-aqueous solution.
A method for producing a polymer, wherein a polymerizable monomer is polymerized in the reaction vessel according to any one of claims 1 to 3.
The polymerizable monomer is an aliphatic conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, an ethylenically unsaturated carboxylic acid ester monomer, an alkenyl aromatic monomer, a vinyl cyanide monomer The method for producing a polymer according to claim 4, wherein the polymer is one or more monomers selected from the group consisting of unsaturated carboxylic acid amide monomers.
The method for producing a polymer according to claim 5, wherein the polymerizable monomer further contains a monomer copolymerizable with the monomer according to claim 5.
The method for producing a polymer according to claim 4, wherein at least a part of the polymerizable monomer is added to the reaction vessel in the form of an emulsion and emulsion polymerization is performed.
The method for producing a polymer according to claim 7, wherein a surfactant, a water-soluble polymer protective colloid or an alkali-soluble resin is used as an emulsifier for preparing the monomer emulsion.
The method for producing a polymer according to claim 7, wherein the monomer emulsion does not contain a polymerization initiator.
The method for producing a polymer according to claim 7, wherein all of the polymerizable monomer is added to the reaction vessel in the form of an emulsion.
The method for producing a polymer according to claim 4, wherein the polymerization is started after the entire amount of the polymerizable monomer is supplied to the reaction vessel.
The method for producing a polymer according to claim 4, wherein after a part of the polymerizable monomer is supplied to the reaction vessel, the polymerization is started and the remaining polymerizable monomer is sequentially supplied to the reaction vessel.
The method for producing a polymer according to claim 4, wherein the polymerizable monomer is supplied after the latex for seed is charged in a reaction vessel in advance.
14. The method for producing a polymer according to claim 13, wherein the total monomer composition of the polymerizable monomer and the monomer composition of the seed latex are the same.
The method for producing a polymer according to claim 13, wherein the total monomer composition of the polymerizable monomer and the monomer composition of the seed latex are different.
The method for producing a polymer according to any one of claims 4 to 15, wherein the obtained polymer is a binder for an electrochemical element.