JPH0572708B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to manganese oxide for dry batteries.
More specifically, a manganese oxide for dry batteries that is active and has good discharge characteristics is characterized by mixing chemical manganese dioxide that has a specific X-ray diffraction peak with natural manganese dioxide that also has a specific X-ray diffraction peak. Regarding. Conventional technology Manganese oxide, especially manganese dioxide, is used as a depolarizing material among the main materials of dry batteries, but its properties have a very large effect on the performance of dry batteries, such as discharge life, so it is difficult to design dry batteries. It has become a very big factor. Among various types of batteries, manganese dry batteries in particular have been widely used in the past, probably because manganese dioxide ore is relatively inexpensive and available in large quantities as a natural product. However, in recent years, it has become increasingly difficult to obtain high-quality manganese oxide for dry batteries from natural ores, and as a result, many attempts have been made to artificially produce high-quality manganese dioxide. The best known example is electrolytic manganese dioxide. This electrolytic manganese dioxide is usually obtained by anodizing manganese sulfate and has a crystalline phase mainly consisting of gamma (γ) type MnO ₂ (see X-ray spectrum chart (d) in attached Figure 6). , is generally considered to be the most suitable depolarizing material. However, in order to obtain electrolytic manganese dioxide, an electrolytic oxidation step is essential and requires a large amount of electric power, resulting in problems such as high product cost and significant energy consumption. Therefore, it is desired to develop a technology that is more economically efficient without sacrificing the battery characteristics as a product as much as possible. Recently, attempts have been made to synthesize active manganese dioxide, which is made highly active by chemically treating inert natural manganese dioxide, for use in dry batteries, and to synthesize chemical manganese dioxide from manganese ore and manganese salts using chemical methods. . Examples of such chemical manganese dioxide include:
Examples include those described in JP-A-60-170891 by the present inventors, which can be produced by the following method. That is, manganese ore or manganese salt is heated to 400℃.
After roasting at the above temperature, acid treatment is performed to produce manganese dioxide, and the manganese dioxide can be made heavier. In particular, chemical manganese dioxide obtained by roasting and acid-treating manganese ore can be used as an inexpensive depolarizing material for dry batteries, but the quality of manganese dioxide is 91 to 92% that of electrolytic manganese dioxide. On the other hand, it is low at around 75-82%, and is not as good as electrolytic manganese dioxide in terms of light discharge performance with a high utilization rate of manganese dioxide. Hereinafter, in this specification, relatively low-grade manganese oxide obtained by roasting and acid-treating manganese ore will be referred to as chemical manganese dioxide. In other words, the utilization rate of manganese dioxide in dry cell discharge is generally lower in heavy discharge (low resistance).
While it is 35-40%, in light discharge (high resistance) it reaches 80-100%, and most of the manganese dioxide contained in the dry battery anode mixture is used for discharge. Therefore, in light discharge, the quality of manganese dioxide has a close relationship with battery performance. Generally, as a method of improving the light discharge performance of low-grade manganese dioxide, a method of mixing this with high-grade electrolytic manganese dioxide is adopted. However, as mentioned above, electrolytic manganese dioxide is an expensive manganese oxide and has the drawback that the price of the dry battery product is also high. Problems to be Solved by the Invention As mentioned above, the conventional manganese oxide for dry batteries has various drawbacks that need to be solved, and from the viewpoint of cost and battery performance, it is difficult to improve light discharge performance. This is an extremely important issue. From the viewpoint of battery performance, as mentioned above, it is possible to achieve the objective with electrolytic manganese dioxide or a mixture of this and low-grade manganese dioxide, but as long as electrolytic manganese dioxide is used, the price is significantly lower. It is disadvantageous. Therefore, from an economic point of view, it is desirable to use low-grade manganese dioxide or chemically modified manganese dioxide to obtain a product that is above the practical level, or equivalent to or better than electrolytic manganese dioxide or its mixture with low-grade products. Most desirable. Therefore, an object of the present invention is to provide a manganese oxide for dry batteries that is highly active, exhibits excellent performance particularly in light load discharge performance, and is significantly cheaper than when electrolytic manganese dioxide is used. Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have conducted various studies and, as a result of their consideration, have found that chemical manganese dioxide exhibiting a specific X-ray diffraction peak and chemical manganese dioxide exhibiting a specific X-ray diffraction peak The present invention has been completed based on the discovery that the combination with natural manganese dioxide having the following properties is extremely effective for achieving the above object. That is, the manganese oxide for dry batteries of the present invention has
12.8°, 18.1°, 22.4°, 28.8°, 34.7°, 37.1 in the diffraction lines by X-ray diffraction using CuXα rays as the radiation source
°,
37.6°, 38.8°, 41.9°, 42.6°, 44.1°, 49.8°, 56
.1°,
Chemical manganese dioxide has unique peaks near 57.4°, 60.0°, 65.6°, and 68.8°, and diffraction lines of 9.4°, 12.3°, 18.7°, 22.4°, and 28.6° by the same method.
,
34.7°, 37.1°, 38.8°, 42.6°, 44.1°, 56.1°, 57
.4°,
It is characterized by consisting of natural manganese dioxide having unique peaks near 65.6° and 68.8°. Such a combination greatly improves light load discharge performance and enables cost reduction. A similar effect can also be obtained from electrolytic manganese dioxide, chemically synthesized manganese dioxide, and natural manganese dioxide having peaks other than around 9.4°, 12.3°, and 18.7° among the peaks of the above natural manganese dioxide. This can also be achieved by adding at least one member selected from the group consisting of: This embodiment also falls within the scope of the present invention. In the manganese oxide for dry batteries of the present invention,
At the line diffraction peak, the diffraction lines are approximately 9.4°, 12.3°, 18.7°,
22.4°, 28.6°, 34.7°, 37.1°, 38.8°, 42.6°, 44
.1°,
Examples of natural manganese dioxide having characteristic peaks at 56.1°, 57.4°, 65.6° and 68.8° include, in particular, those from Gabon in Africa. Among the diffraction lines, 22.4°, 34.7°, 37.1°, 38.8°, 42.6°, 44
.1°,
What has diffraction peaks at 56.1°, 57.4°, 65.6°, and 68.8°, respectively, is called gamma (γ) type-MnO ₂ and is electrochemically extremely active manganese dioxide. Additionally, 9.4°, 12.3°, 18.7°
Those with diffraction peaks in (Mn,
Ca) Mn ₅ O _{11.4H 2} O, which is a manganese oxide that is considered to be the main cause of the effects of the manganese oxide of the present invention. The diffraction peak shown at 28.6° is the strongest peak of beta (β) type MnO ₂ , which is electrochemically inert manganese dioxide, but due to its good crystallinity, it is extremely sharp even if it is contained in small amounts. Appears as a diffraction peak. These three types of manganese oxides exist extremely stably at a certain ratio in the ore, and the ore itself is inexpensive and widely available. On the other hand, similarly, 12.8°, 18.1°, 22.4°, 28.8°,
34.7°, 37.1°, 37.6°, 38.8°, 41.9°, 42.6°, 44
.1°,
Chemical manganese dioxide having diffraction peaks around 49.8°, 56.1°, 57.4°, 60.0°, 65.6°, and 68.8° can be obtained by a method for which a patent application has been separately filed by the present inventors. 60-170891). That is, manganese ore or manganese salt is heated to 400℃.
After roasting at the above temperature, acid treatment is performed to produce manganese dioxide, and the manganese dioxide can be made heavier. The manganese ore used as a raw material here is preferably one whose main components are MnO ₂ (soft manganese ore), MnCO ₃ (rhomganese ore), Mn ₂ O ₃ , Mn ₃ O ₄ , etc., and as the manganese salt, _MnSO4 ,
MnCO ₃ , Mn(NO ₃ ) _2, etc. are used. Generally, manganese oxide and MnCO ₃ become Mn ₂ O ₃ from around 400 to 500℃ by heating in an autogenous atmosphere, and further from around 800 to 1000℃.
Mn ₂ O ₃ becomes Mn ₃ O ₄ . Furthermore, MnSO ₄ decomposes at 850°C to become Mn ₃ O ₄ , and when further heated at 530 to 940°C, it is oxidized to generate Mn ₂ O ₃ . Furthermore, when soft manganese ore (MnO ₂ ) is used, reduction roasting is performed to produce Mn ₂ O ₃ or Mn ₃ O ₄ . Mn ₂ O ₃ or
Mn ₃ O ₄ using an acid such as H ₂ SO ₄ , HCl, HNO ₃ , etc.
Manganese dioxide (MnO ₂ ) is obtained by acid treatment at a predetermined temperature and acid concentration. Chemical manganese dioxide, which is a component of manganese oxide for dry batteries as intended by the present invention, can be obtained by following the procedures described above, but if necessary, potassium, gangue components, By removing heavy metal components and the like, a more electrically advantageous manganese oxide can be obtained. This acid treatment is usually performed using an acid solution of about 0.5 to 6N at 60 to 95°C for about 30 to 120 minutes. These processing conditions are not particularly critical, and vary depending on conditions such as the particle size of the crushed manganese ore and manganese salt, and the amount to be processed. For example, treatment with sulfuric acid yields a solid content mainly consisting of manganese dioxide and a solution containing soluble manganese sulfate, but most of the impurities remain in the latter solution. The solid content is recovered as a final product. Of course, wash thoroughly with water to remove soluble potassium and heavy metals. It is also possible to neutralize with an alkali such as NH ₄ OH, which is free from contamination with K, etc., then wash with water and dry. The manganese dioxide thus obtained is then made heavy. This weighting is carried out by compressing the acid-treated manganese dioxide in a powder state into a flat plate by roll pressing under pressure, and then pulverizing it to a desired particle size. The manganese oxide of the present invention can be obtained by mixing the chemical manganese dioxide thus obtained with natural manganese dioxide and/or at least one of the other components mentioned above, which have been similarly ground and adjusted to a predetermined particle size. Incidentally, the weighting can also be carried out all at once after mixing these components. Function Thus, according to the present invention, light discharge performance can be significantly improved by mixing natural manganese dioxide having a specific X-ray diffraction peak with chemical manganese dioxide. FIG. 1 shows the X-ray diffraction pattern of the manganese dioxide,
FIG. 2 shows an example of such an effect of the present invention. The data in the figure shows the relationship between the mixing ratio and the 10 ohm continuous discharge duration, which is an example of light discharge performance. It is shown that when manganese alone is mixed for 32.0 hours, the performance is significantly improved at all mixing ratios. Generally, it is well known that when high-performance manganese dioxide and low-performance manganese dioxide are mixed, the performance decreases linearly (indicated by the dotted line in the figure) according to the mixing ratio. However, the manganese dioxide mixture of the present invention shows a convex curve above the straight line without decreasing linearly, indicating that the performance is improved at all mixing ratios. Furthermore, the manganese oxide for dry batteries according to the present invention contains one or more types of electrolytic manganese dioxide, chemically synthesized manganese dioxide, and approximately
22.4°, 34.7°, 37.1°, 38.8°, 42.6°, 44.1°, 56
.1°,
Even when natural manganese dioxide having diffraction peaks at 57.4°, 65.6°, and 68.88° is added and mixed, the performance of the manganese dioxide for dry batteries according to the present invention can be sufficiently achieved. There are no particular restrictions on the weight ratio that can be added and mixed, but it is preferably small in terms of price and manufacturing cost. As mentioned above, electrolytic manganese dioxide has excellent quality as manganese dioxide for dry batteries and the discharge characteristics of batteries obtained using it.
It is clear that if this is mixed with other manganese dioxide, the light discharge characteristics of the battery will be improved. For example, it is a common practice to mix electrolytic manganese dioxide with natural manganese dioxide from Gabon to achieve desired performance, and one example is shown in FIG. As is clear from the figure, the battery performance obtained by mixing changes almost linearly according to the mixing ratio, and the discharge duration is also long. However, electrolytic manganese dioxide has the disadvantage that it is significantly more expensive than chemical manganese dioxide, and the resulting dry battery product is also expensive. Therefore, as already mentioned, it is desirable that the manganese oxide to be added to chemical manganese dioxide be inexpensive. However, not all low-priced manganese oxides are effective; for example, among the many natural manganese dioxides, some are used as manganese dioxide for batteries because they have relatively large reserves and are cheap. When natural manganese dioxide produced in Mexico is mixed with chemical manganese dioxide according to the present invention, as shown in Fig. 4, the battery performance changes only linearly according to the mixing ratio; The absolute value of the discharge duration is also lower compared to the manganese oxide of the present invention. Thus, the manganese oxide according to the present invention can be effectively used, for example, as a depolarizing material for manganese dry batteries, etc., which are produced in the largest quantity, by utilizing such properties, and can improve light discharge characteristics and reduce the price. It is also fully satisfactory in terms of. Examples The method of the present invention will be specifically explained below based on Examples, but the scope of the present invention is not limited in any way by these Examples. Example 1 After crushing manganese ore to 5 mm or less, it was crushed in the atmosphere.
It was roasted at a temperature of 800°C for 1 hour to obtain manganese oxide. The manganese oxide was mixed with 2N−H ₂ SO ₄ and 1.5
Acid treatment was carried out by reacting for a period of time. After washing the obtained solid with water, the pH was adjusted to 7.5 with a dilute NH ₄ OH solution.
After drying at 120℃, the diffraction lines were determined by X-ray diffraction using CuKα as the X-ray source.
12.8°, 18.1°, 22.4°, 28.8°, 34.7°, 37.1°, 37
.6°,
38.8°, 41.9°, 42.6°, 44.1°, 49.8°, 56.1°, 57
.4°,
Chemical manganese dioxide having unique peaks at 60.0°, 65.6°, and 68.8° was obtained. In addition, during X-ray analysis
When CuKα is used as a radiation source, the baseline of the diffraction peak becomes high due to the influence of X-ray scattering, making it difficult to determine the peak, so a monochromator, which acts as a filter, was used. However, even if a monochromator is used, the angle of the diffraction peak does not change. The measurement voltage was 30KV, the current was 15mA, and the full scale was 400cps. The manganese oxide thus obtained was then placed in a roll press and pressed at a pressure of 5 tons/ ^cm2 .
It was pressed to make it heavier and ground to a particle size smaller than 100 mesh. Next, natural manganese dioxide from Gabon was crushed using a roll crusher and a vibrating ball mill to obtain a -200 mesh particle size. The chemical manganese dioxide thus obtained and the natural manganese dioxide from Gabon were mixed in a weight ratio of 100:0,90.
vs. 10, 80 vs. 20, 70 vs. 30, 60 vs. 40, 50 vs. 50, 40 vs.
60:60, 30:70, 20:80, 10:90, and 0:100 were mixed using a forced stirring type mixer to obtain 9.6 kg of manganese oxide for dry batteries, respectively. JIS-
Three hundred single-type dry batteries were manufactured in accordance with the dry battery prototype testing method described in No. K1467. In the discharge test, continuous discharge was performed under a resistance of 10 ohms at a temperature of 20±2° C., and the discharge duration until the discharge end voltage (0.9 volts) was measured. The results are shown in Figure 2. The dotted line indicates the general tendency observed in such mixtures. Examples 2 to 7 Manganese dioxide mixtures were obtained in the same manner as in Example 1 using the raw materials shown in Tables 1 and 2 below, and batteries were produced in the same manner and their characteristics were evaluated.
Note that Example 2 is a reference example, and Examples 3 and 4
is a comparative example. The test methods and results from Example 1 to Example 7 are shown in Table 1, Table 2, and FIG. 6. Here, as a method of expressing the effect of the present invention,
The case where the performance improves in an arcuate manner according to the mixing ratio is referred to as ``there is an arcuate phenomenon,'' and the case where it simply changes linearly is referred to as ``there is no arcuate phenomenon.''

【table】

【table】

【table】

[Table] Effects of the invention As described in detail above, according to the manganese oxide for dry batteries of the present invention, it is possible to improve the light discharge performance of chemical manganese dioxide by mixing inexpensive natural manganese dioxide. In turn, it becomes possible to significantly reduce the cost of the manganese dry battery product. From the above, it can be said that the manganese oxide for manganese dry batteries of the present invention is industrially extremely useful.

[Brief explanation of the drawing]

Figure 1 shows chemically converted manganese dioxide (a) and natural manganese dioxide useful in the manganese oxide of the present invention.
FIG. 2 is a diagram showing the X-ray diffraction peak of (b), and FIG.
This is a graph showing the relationship between the mixing ratio of chemical manganese dioxide and natural manganese dioxide produced in Gabon and the discharge duration of a dry battery. 4 is a graph showing the relationship between the discharge duration and the mixing ratio of chemical manganese dioxide and natural manganese dioxide produced in Mexico and the dry battery discharge duration,
FIG. 5 is a graph showing the relationship between the mixing ratio of electrolytic manganese dioxide and natural manganese dioxide produced in Mexico and the dry cell discharge duration, and FIG.
X of various manganese oxides used in the examples
It is a diagram showing the line diffraction patterns of chemical manganese dioxide (a) according to the present invention, natural manganese dioxide from Gabon (b) according to the present invention, natural manganese dioxide from Mexico (c), and international common sample No. 17, respectively. Electrolytic manganese dioxide (d) International common sample No. 12 shows chemically synthesized manganese dioxide (e).

Claims (1)

[Claims] 1. 12.8°, 18.1°, 22.4°, 28.8°, 34.7° in diffraction lines by X-ray diffraction using CuKα rays as an X-ray source
,
37.1°, 37.6°, 38.8°, 41.9°, 42.6°, 44.1°, 49
.8°,
Chemical manganese dioxide has unique peaks near 56.1°, 57.4°, 60.0°, 65.6° and 68.8°, and diffraction lines of 9.4°, 12.3°, 18.7°, 22.4°,
28.6°, 34.7°, 37.1°, 38.8°, 42.6°, 44.1°, 56
.1°,
A manganese oxide for dry batteries consisting of natural manganese dioxide having unique peaks near 57.4°, 65.6°, and 68.8°. 2 The chemical manganese dioxide mentioned above is soft manganese, rhodochrosite, Mn ₂ O ₃ , Mn ₃ O ₄ , MnCO ₃ , Mn
The manganese oxide for dry batteries according to claim 1, which is obtained by roasting at least one of (NO ₃ ) ₂ at a temperature of 400° or higher and then treating with an acid. . 3. The manganese oxide for dry batteries according to claim 1 or 2, wherein the natural manganese dioxide is natural manganese dioxide produced in Gabon. 4 12.8°, 18.1°, 22.4°, 28.8°, 34.7° in the diffraction lines by X-ray diffraction using CuKα rays as the X-ray source
,
37.1°, 37.6°, 38.8°, 41.9°, 42.6°, 44.1°, 49
.8°,
Chemical manganese dioxide has unique peaks near 56.1°, 57.4°, 60.0°, 65.6° and 68.8°, and diffraction lines of 9.4°, 12.3°, 18.7°, 22.4°,
28.6°, 34.7°, 37.1°, 38.8°, 42.6°, 44.1°, 56
.1°,
A mixture with natural manganese dioxide having unique peaks around 57.4°, 65.6°, and 68.8°, and diffraction lines other than those around 9.4°, 12.3°, and 18.7° of electrolytic manganese dioxide, chemically synthesized manganese dioxide, and the natural manganese dioxide. A manganese oxide for dry batteries, characterized in that it contains at least one member selected from the group consisting of natural manganese dioxide having a peak of 5 The chemical manganese dioxide mentioned above is soft manganese, rhodochrosite, Mn ₂ O ₃ , Mn ₃ O ₄ , MnCO ₃ , Mn
The manganese oxide for dry batteries according to claim 4, which is obtained by roasting at least one type of (NO ₃ ) ₂ at a temperature of 400° or higher and then treating with an acid. . 6. The manganese oxide for dry batteries according to claim 4 or 5, wherein the natural manganese dioxide is natural manganese dioxide produced in Gabon.