JP2002097277A - Method of producing additive for lead storage battery and lead storage battery using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lead storage battery having a long life. SOLUTION: This additive for a lead storage battery is obtained by the steps of adding an acid to a lignocellulosic substance comprising a phenol derivative having a methoxy group, mixing and separating to obtain lignin, and polymerizing the lignin using formaldehyde. This lead storage battery uses the additive for the negative electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to extending the life of a lead storage battery.

[0002]

2. Description of the Related Art Lead-acid batteries are used in a wide range of fields such as uninterruptible power supplies, automobile batteries, and electric vehicles because of their excellent cost and reliability. Recently, it has been strongly desired to extend the life of lead-acid batteries used in these batteries.

To extend the life of a lead-acid battery, the active material used in the negative electrode plate is made finer or porous to increase the electrode reaction area of the negative electrode plate, and the state of the negative electrode plate is extended over a long period of time. Need to be retained.

There is lignin as a material (hereinafter, referred to as an expander) for making the negative electrode active material finer or porous, and the lignin is added to the negative electrode active material layer or a retainer is provided at a portion in contact with the negative electrode plate. It is known that a technique of impregnating the sapphire is effective.

[0005] On the other hand, the above-mentioned lignin can be obtained as a by-product of a process of producing pulp (cellulose) from lignocellulose (constituent substance of vegetation such as wood) in the papermaking industry. The lignin is present in a three-dimensional network between cells forming wood, and functions as a binder connecting the cells.

[0006] In the paper industry, chips obtained by crushing wood are
It is separated into cellulose and lignin by digestion and treatment under conditions of high temperature and high pressure by alkaline cooking method (also called kraft cooking method) or sulfite cooking method.

[0007] In the lignin obtained by these techniques (hereinafter referred to as industrial lignin), the lignin obtained by alkaline cooking is called kraft lignin, and the lignin obtained by sulfite cooking is called lignin sulfonic acid. I'm calling

[0008]

However, since the production of industrial lignin in the paper industry described above is performed under high temperature and high pressure conditions, a part of the three-dimensional structure of lignin is destroyed. The resulting industrial lignin has its structure destroyed randomly and is highly modified at the molecular level, resulting in inactivation of its constituent functional groups and its stability. Has been impaired.

When these industrial lignins are used in lead storage batteries used in a high-temperature environment exceeding 60 ° C., there is a problem that the effect as an expander is lost in a short time.

Various organic compounds (sulfonic acid-based surfactants, formalin condensates of β-naphthalenesulfonic acid, polymer-based surfactants, etc.) have been studied as additives replacing these industrial lignins. . However, in reality, no substitute for the above-mentioned industrial lignin has been found up to the present.

The present invention has been made in consideration of the above circumstances, and has as its object to provide a long-life lead-acid battery by using lignin having a more excellent effect as an expander.

[0012]

In order to solve the above-mentioned problems, the present invention provides an additive prepared by a method in which lignin is extracted by adding an acid to wood powder to which a phenol derivative is added, and lignin is subjected to addition polymerization. The agent is used as an expander for a lead storage battery.

That is, the first invention is to add an acid to a lignocellulosic substance to which a phenol derivative is added,
A lignin is prepared by mixing and separating, and the lignin is polymerized using a polymerization agent.The second invention is characterized in that the phenol derivative has a methoxy group, and the phenol derivative has a methoxy group. The invention is characterized in that formaldehyde is used as the polymerization agent.

A fourth invention is characterized in that the additive for a lead storage battery produced by the above-mentioned method is used in a negative electrode plate of a lead storage battery.

[0015]

Embodiments of the present invention will be described below.

1. Preparation of Lignin 1 Lignin 1 as an expander was prepared by the following method. That is, as lignocellulose powder,
Beech wood flour, a hardwood, was used. The average particle diameter of the wood flour is about 0.5 mm.

As a phenol derivative, 2,6-dimethoxyphenol was used. 10 g of the 2,6-dimethoxyphenol was dissolved in an amount of acetone in which the wood flour was completely immersed to form a solution. This is added to 10 g of the wood flour, and the acetone is covered with a lid so as not to volatilize and left for 24 hours to sufficiently penetrate into the wood flour.

Then, acetone was spontaneously vaporized in the air to obtain wood powder impregnated with 2,6-dimethoxyphenol.

Thereafter, 50 ml of 70% by weight sulfuric acid is added to the wood powder impregnated with 2,6-dimethoxyphenol, and the mixture is vigorously stirred at room temperature for 60 minutes. Here, when 50 ml of phenol: benzene = 8: 2 (vol%) is added, the wood flour is separated into a sulfuric acid phase containing cellulose and a phenol phase containing lignin.

In this state, using a centrifuge, 3500
After treatment at 10 rpm for 10 minutes, the phenol phase containing lignin was added dropwise to a large excess of ethyl ether to give 2,2.
Lignin into which 6-dimethoxyphenol was introduced was extracted. Hereinafter, this lignin is temporarily referred to as lignin 1.

2. Preparation of Lignin 2 As an expander, Lignin 2 having an increased molecular weight by subjecting the above lignin 1 to addition condensation with formaldehyde was prepared.

That is, the lignin 1 is 32.0 g,
After mixing 12.3 g of a 37% by mass formaldehyde solution, the mixture is mixed while adding an aqueous sodium hydroxide solution to adjust the alkali concentration in the solution to 0.2N.
After the solution is reacted at 70 ° C. for 2 hours, 10% by mass of sulfuric acid is added to adjust the pH of the solution to 3-4. Lignin, which is a sedimentation section of this solution, was collected, dried, and ground in a mortar to obtain lignin as a powder. Hereinafter, this lignin is temporarily referred to as lignin 2.

3. Preparation of Lignin 3 As an expander, lignin 3 was prepared by subjecting the above-mentioned lignin 1 to addition condensation with formaldehyde by a method different from that of the above-mentioned lignin 2 to increase the molecular weight.

That is, 44.0 g of lignin 1 and 37
9.2 g of a mass% formaldehyde solution and 1.3 g of water are mixed, and 0.2 g of 10% sulfuric acid is added. The acidic solution is heated to reflux using a reflux condenser for 1.5 hours. Lignin, which is a sedimentation section of this solution, was collected, dried, and ground in a mortar to obtain lignin as a powder. Hereinafter, this lignin is temporarily referred to as lignin 3.

4. A commercially available lignin powder (trade name: INDULIN, manufactured by Westvaco), which has been conventionally used as a commercially available lignin expander, was used. This lignin powder is obtained by producing wood crushed chips by an alkaline cooking method.

The above-mentioned lignins 1 to 3 and commercially available lignin are THF as a solvent and KF804, KF as a column.
The weight average molecular weight was measured with a high performance liquid chromatograph (manufactured by Shimadzu Corporation) using 803, KF802, and KF801.

5. Anode plate 100 parts by mass of lead powder mainly composed of lead oxide (PbO)
A mixture is prepared by adding and mixing 1 part by mass of barium sulfate and 0.2 part by mass of the various lignin powders described above. Then, 10 parts by mass of dilute sulfuric acid having a specific gravity of 1.26 and 7 parts by mass of water were added to 100 parts by mass of the lead powder in the mixture and kneaded to prepare a paste-like active material for a negative electrode.

[0028] The paste active material, ^l 70mm × ^w 4
Filled into a 5 mm × ^t 2.4 mm lead-calcium-tin alloy current collector grid, temperature 45 ° C., humidity 98 RH
%, And dried at an atmosphere temperature of 60 ° C. for 16 hours to obtain an unplated plate. This unplated plate,
A negative electrode plate was formed by chemical conversion in dilute sulfuric acid having a specific gravity of 1.050 for 24 hours.

6. Positive Electrode Plate A conventionally used positive electrode plate was used. That is, 12 parts by mass of dilute sulfuric acid having a specific gravity of 1.34 and 100 parts by mass of lead powder containing lead oxide (PbO) as a main component,
5 parts by mass were added and kneaded to prepare a paste-like active material for a positive electrode.

The paste-like active material was obtained by adding ¹ 69 mm × ^w 4
4 mm × ^t 3.7 mm of lead - calcium - was filled in a collector Taikakuko consisting of tin alloy, the temperature 45 ° C, humidity 98RH
%, And dried at an atmosphere temperature of 60 ° C. for 16 hours to obtain an unplated plate. This unplated plate,
A positive electrode plate was formed by chemical conversion in dilute sulfuric acid having a specific gravity of 1.050 for 24 hours.

7. Manufacturing and Testing of Lead-Acid Batteries The above-mentioned four negative plates and three positive plates are laminated and welded via a conventionally used retainer to assemble an electrode group. Was assembled in an ABS battery case, and a lid was attached. A dilute sulfuric acid electrolyte solution having a specific gravity of 1.31 (20 ° C.) was placed in the battery case.
After injecting 6 ml, the container was sealed to produce a 7Ah-2V small-sized control valve type lead storage battery.

The initial discharge capacity of the small control valve type lead-acid battery was measured at 25 ° C. by discharging at a current value of 21 A (3 CA) (discharge end voltage: 1.3 V). The life of the control valve type lead-acid battery was determined by using an accelerated test method. That is, 6
8 at a constant voltage of 2.275 V / cell in a temperature atmosphere of 0 ° C.
After performing continuous overcharge for a month and periodically cooling to 25 ° C., the battery was discharged at a current value of 21 A (3 CA), and the discharge capacity was measured and compared with the initial discharge capacity.

Incidentally, the discharge capacity after the above-mentioned continuous overcharge test at 60 ° C. for 8 months is generally expected to correspond to the discharge capacity after use for 7 years in an environment of 25 ° C. .

[0034]

Embodiments of the present invention will be described below.

Comparative Example 1 0.2 mass parts of the above-mentioned commercially available lignin powder (trade name: INDULIN, manufactured by Westvaco) as an expander was added to 100 parts by weight of lead powder mainly composed of lead oxide (PbO). A negative electrode plate prepared by addition was used.
The specifications of the negative electrode plate are those conventionally used. The other conditions for producing the negative electrode plate and the small control valve type lead-acid battery and the test conditions for the small control valve type lead-acid battery are as described above.

Comparative Example 2 A negative electrode plate prepared by adding 0.2 parts by weight of the above-mentioned lignin 1 powder as an expander to 100 parts by weight of lead powder containing lead oxide (PbO) as a main component was used. . The other conditions for producing the negative electrode plate and the small control valve type lead-acid battery and the test conditions for the small control valve type lead-acid battery are as described above.

Example 1 A negative electrode plate prepared by adding 0.2 parts by weight of the above-mentioned lignin 2 powder as an expander to 100 parts by weight of lead powder mainly containing lead oxide (PbO) was used. . The other conditions for producing the negative electrode plate and the small control valve type lead-acid battery and the test conditions for the small control valve type lead-acid battery are as described above.

(Example 2) A negative electrode plate prepared by adding 0.2 parts by mass of the above-mentioned lignin 3 powder as an expander to 100 parts by weight of lead powder containing lead oxide (PbO) as a main component was used. . The other conditions for producing the negative electrode plate and the small control valve type lead-acid battery and the test conditions for the small control valve type lead-acid battery are as described above.

Table 1 shows the specifications of the various expanders and the discharge time of the small control valve type lead-acid battery at the initial stage and at 60 ° C. for 8 months. As shown in Table 1, it can be seen that the batteries of Examples 1 and 2 using the present invention have a longer life than the batteries of Comparative Examples 1 and 2. Then, as shown in the results of Examples 1 and 2, the molecular weight of the lignin compound was 10,000 to 2,000.
It can be seen that it is preferable to set to 0.

The lignin obtained by the conventional kraft digestion or sulfite digestion has a variable molecular weight due to random depolymerization or self-condensation of molecules, and has a phenol group or methoxy group which effectively acts as an expander. This is probably because the group has been lost.

On the other hand, when the present invention is used, the molecular weight can be made substantially constant, and the presence of a phenol group or a methoxy group which effectively acts as an expander makes it possible to reduce the length of a small control valve type lead-acid battery. It is considered that the life was extended.

[0042]

[Table 1]

In the above-described embodiment, the case where the present invention is applied to a small-sized control valve type lead-acid battery has been described. However, the present invention is not limited to the use and shape of the lead-acid battery, but may be used in the above-described claims. Can be.

In the examples, 2,6-dimethoxyphenol was used as the phenol derivative.
Cresol, catechol, 2-methoxyphenol,
2,6-dimethylphenol and the like can also be used.

[0045]

As described above, the use of the present invention makes it possible to extend the life of a lead storage battery, which is industrially excellent.

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Claims (4)

[Claims] An additive for a lead storage battery, comprising adding an acid to a lignocellulosic substance to which a phenol derivative has been added, mixing and separating to form lignin, and polymerizing the lignin using a polymerizing agent. Method of manufacturing the agent. 2. The method for producing an additive for a lead storage battery according to claim 1, wherein a phenol derivative having a methoxy group is used. 3. The method for producing an additive for a lead storage battery according to claim 1, wherein formaldehyde is used as said polymerizing agent. 4. A lead-acid battery, wherein the additive for a lead-acid battery according to claim 1 is used in a negative electrode plate of the lead-acid battery.