JP2010110770A - Parting agent for casting lattice body for electrode plate of lead battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cork powder-containing parting agent which hardly falls from a die face and imparts suitable thermal insulation properties upon casting a lattice body for an electrode plate used for a lead battery, and which has a remarkably long life as a result, also which enables the molten metal of lead alloy to be uniformly spread to all the corners of the whole of the die, and enables the molten metal of the lead alloy to be solidified in a short period of time, and therefore achievs production of an extremely homogeneous lattice body for the electrode plate with remarkably high productivity by the synergistic action of the above effects. <P>SOLUTION: In the cork powder-containing parting agent used for casting a lattice body for a lead battery electrode plate, the cumulative value of grains with a grain size of ≥100 μm in the cork powder is 1 to 10 mass%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a mold release agent applied to a mold of a grid used for an electrode plate of a lead storage battery, and more particularly to the mold release agent containing cork powder.

Gravity casting method and continuous casting method are widely used as a method of manufacturing a lattice used as an electrode plate of a lead storage battery. For example, in the gravity casting method, first, a mold release agent is applied to the mold surface, then molten lead alloy hot water is poured into the mold, and after the hot water is cooled and solidified, it is removed from the mold, Cut into dimensions to make a grid.

As the mold release agent, a dispersion in which cork powder containing sodium silicate is dispersed in water is usually used, and the dispersion is applied to the mold surface with a spray gun or the like. In this way, the layer of cork powder applied to the mold surface acts as a heat insulating layer to improve the heat retention of the poured lead alloy hot water, and thereby uniformly distribute the hot water to every corner of the mold. In addition to being able to act as a mold release agent, the solidified lead alloy can be easily taken out of the mold. However, since the cork powder layer is inferior in heat resistance and weak against mechanical shock, it gradually falls off the mold surface when repeated casting is performed. Therefore, it becomes necessary to apply a layer of cork powder again during the casting operation. Accordingly, not only will the productivity be reduced, but also the weight and thickness of the lattice produced will be subject to variations due to the dropping of the cork powder layer.

Therefore, various efforts have been made to prevent the cork powder layer from falling off and to increase its lifetime. For example, a solution obtained by adding a predetermined amount of a thermosetting resin water-soluble varnish having heat resistance to a solution in which cork powder having a particle size of about 1 to 100 microns is dispersed at a predetermined concentration is applied to the inner surface of a lattice casting mold. A grid casting method for a lead storage battery in which casting is performed using the mold after spraying is known (Patent Document 1). Further, a lead grid casting mold is known in which a protective layer made of an inorganic substance powder and an inorganic substance binder is formed on the upper surface of a heat insulating layer made of cork powder and a binder (Patent Document 2). However, these inventions have a problem that a predetermined water-soluble varnish and a protective layer are necessary, and the work becomes complicated and the cost is increased.

Furthermore, in a lead storage battery casting mold having an engraved surface of a lead storage battery grid, a lead storage battery grid casting mold having a coating layer with a maximum surface roughness of 70 μm or less on the engraving surface is known. (Patent Document 3). However, in the present invention, in order to obtain a predetermined surface roughness, an operation such as rubbing the surface of the coating layer using sandpaper or the like is necessary, which is extremely complicated and deteriorates productivity.

Moreover, in the Example of patent document 1, the cork powder with a particle size of about 1-5 microns is used. However, if the particle size is too fine as described above, a strong heat insulating layer can be formed, but an appropriate air layer is not formed in the cork layer, and the heat insulating effect is lowered.

Japanese Patent Laid-Open No. 58-20364 JP-A-8-229665 JP-A-8-197230

The present invention provides a cork powder-containing mold release agent that imparts appropriate heat insulation as well as very little drop-off from the mold surface when casting a grid used for an electrode plate of a lead storage battery.

In the method of mixing a binder such as a water-soluble varnish in the cork powder as in the above prior art, the method of coating the cork powder layer with a protective layer, or the method of mechanically adjusting the surface roughness of the cork layer, The performance is significantly reduced and the cost is increased. Therefore, the present inventors have conventionally considered that the cork powder layer may fall out in a short period of time because there is a problem in the particle size distribution, and the basis is that the particle size distribution of the cork powder is adjusted. We returned and made various studies. As a result, the inventors have found that the above problems can be solved by adjusting the particle size of the cork powder used for the release agent as follows, and have completed the present invention.

That is, the present invention
(1) In a cork powder-containing mold release agent used for casting of a lead-acid battery electrode plate, the cumulative value of particles having a particle size of 100 μm or more in the cork powder is 1 to 10% by mass. It is a mold.

As a preferred embodiment,
(2) The mold release agent according to the above (1), wherein the cumulative value of particles having a particle size of 100 μm or more in the cork powder is 2 to 7% by mass,
(3) The release agent according to (1) above, wherein the cumulative value of particles having a particle size of 100 μm or more in the cork powder is 2 to 5% by mass,
(4) The mold release agent according to any one of (1) to (3) above, wherein the cork powder has an average particle size of 30 to 70 μm.
(5) The mold release agent according to any one of (1) to (3) above, wherein the cork powder has an average particle size of 30 to 60 μm,
(6) The mold release agent according to any one of (1) to (3) above, wherein the cork powder has an average particle size of 30 to 50 μm,
(7) The mold release agent according to any one of (1) to (6) above, wherein the cumulative value of particles having a particle size of 10 μm or less in the cork powder is 1 to 12% by mass,
(8) The mold release agent according to any one of (1) to (6) above, wherein the cumulative value of particles having a particle size of 10 μm or less in the cork powder is 1 to 10% by mass,
(9) The mold release agent according to any one of (1) to (6) above, wherein the cumulative value of particles having a particle size of 10 μm or less in the cork powder is 5 to 10% by mass,
(10) In the particle size distribution of the cork powder, the release agent according to any one of (1) to (9) above, wherein particles having a particle size of 0.1 to 200 μm are 90% by mass or more,
(11) In the particle size distribution of the cork powder, the release agent according to any one of the above (1) to (9), wherein particles having a particle size of 0.1 to 200 μm are 95% by mass or more,
(12) In the particle size distribution of the cork powder, the release agent according to any one of the above (1) to (9), wherein the particle having a particle size of 0.1 to 200 μm is 98% by mass or more. be able to.

The cork powder-containing release agent of the present invention has very little drop-off from the mold surface when casting a grid used for the electrode plate of a lead storage battery. Therefore, its lifetime is remarkably long. In addition, since it is possible to impart appropriate heat insulation to the release agent layer, the lead alloy hot water can be uniformly distributed to every corner of the entire mold, while the lead alloy hot water can be solidified within a short time. it can. Therefore, by synergistic action of these effects, it is possible to manufacture a very homogeneous electrode plate lattice body with extremely high productivity.

In the cork powder-containing release agent of the present invention, the upper limit of the cumulative value of particles having a particle size of 100 μm or more in the cork powder is 10% by mass, preferably 7% by mass, more preferably 5% by mass, and the lower limit is 1% by mass, preferably 2% by mass. If the above upper limit is exceeded, the unevenness of the release agent layer becomes severe when applied to the mold surface. Therefore, the mold release agent layer easily falls off due to the flow of the lead alloy hot water during the production of the electrode plate lattice. If it is less than the above lower limit, a strong release agent layer is formed and its drop-off is reduced, while a release agent layer containing an appropriate amount of air cannot be obtained, and the heat insulation is improved more than necessary, The solidification time of lead alloy hot water increases. Therefore, the time required for one casting cycle becomes long, and the productivity is lowered.

The upper limit of the cumulative value of particles having a particle size of 10 μm or less in the cork powder is preferably 12% by mass, more preferably 10% by mass. On the other hand, the lower limit is preferably 1% by mass, more preferably 5% by mass. Exceeding the above upper limit, the air layer necessary for the formed release agent layer is filled with cork particles of 10 μm or less, so that a release agent layer having heat insulation higher than necessary is formed. Accordingly, the solidification rate of the lead alloy hot water may be significantly reduced, and the casting cycle may be increased. If it is less than the lower limit, the bond between the mold release agent layer and the mold surface and the bond between the cork particles forming the mold release agent layer become weak, and the mold release agent layer is likely to fall off due to mechanical impact. By adjusting the cumulative value of particles having a particle size of 10 μm or less in the cork powder to the above range, an appropriate air layer is formed in the release agent layer, and cork particles having a particle size of 10 μm or less are larger cork. By entering a proper amount between the particles of the particles, the bond between the mold release agent layer and the mold surface and the bond between the cork particles forming the mold release agent layer are strengthened, so that there is less loss and more appropriate A release agent layer having heat insulation properties can be formed.

The upper limit of the average particle diameter of the cork powder is preferably 70 μm, more preferably 60 μm, and still more preferably 50 μm. On the other hand, the lower limit is preferably 30 μm. If the above upper limit is exceeded, the unevenness of the release agent layer becomes severe when applied to the mold surface. Therefore, the mold release agent layer easily falls off due to the flow of the lead alloy hot water during the production of the electrode plate lattice. Further, it is not easy to control the cumulative value of particles having a particle size of 10 μm or less in the cork powder to the predetermined value. On the other hand, if it is less than the above lower limit, an appropriate air layer is not formed in the release agent layer, and the heat insulating effect is lowered. Further, it is not easy to control the cumulative value of particles having a particle size of 100 μm or more in the cork powder to the predetermined value.

In the particle size distribution of the cork powder of the present invention, particles having a particle size of 0.1 to 200 μm are preferably present at 90% by mass or more, more preferably 95% by mass or more, and further preferably 98% by mass or more. Preferably, particles having a particle size of 10 to 100 μm are present at 80% by mass or more, more preferably 85% by mass or more. The particle size distribution shows a continuous single peak around a predetermined particle size. A cork powder having a particle size within the above range, the cumulative value of particles having a particle size of 100 μm or more is within the range of the present invention, and preferably the cumulative value and average particle size of particles having a particle size of 10 μm or less are the present invention. Within this range, the change in the particle size distribution of the entire cork powder does not significantly affect the effect of the present invention.

All the above values for the particle size of the cork powder are based on values obtained using laser diffraction and scattering particle size distribution measurements. However, regarding the cumulative value of particles having a particle size of 100 μm or more and the cumulative value of particles having a particle size of 10 μm or less, sieve the cork powder using a sieve having an opening of 100 μm square and a sieve having an opening of 10 μm square, respectively. Thus, the predetermined value can be adjusted.

The cork powder used in the present invention is obtained by pulverizing natural cork, that is, granular cork obtained by pulverizing and purifying bark of cork oak. A commercial item can be used as this granular cork, for example, 200A (trademark) by Nagayanagi Kogyo Co., Ltd. etc. can be mentioned.

There is no particular limitation on the method of pulverizing the granular cork to produce the cork powder having the particle size distribution of the present invention. A well-known thing can be used as a grinder, for example, a jet grinder, a ball mill, a vibration mill, a disk mill, a hammer mill etc. can be used.

The cork powder of the present invention can be easily produced by appropriately changing the pulverization conditions of the above pulverizers. For example, when using a dry jet pulverizer, cork powder having a desired particle size distribution and average particle size is produced by appropriately adjusting the amount of granular cork fed to the pulverizer, the supply pressure, and the pulverization pressure. be able to. In addition, the cork powder obtained in this manner can be appropriately adjusted using a sieve having 100 μm squares and 10 μm square sieves, and appropriately adjusting the cumulative values of particles having a particle size of 100 μm or more and particles having a particle size of 10 μm or less.

The cork powder produced as described above is used as a mold release agent in the casting of a lattice used as an electrode plate of a lead storage battery according to a conventional method. In addition to the cork powder of the present invention, the mold release agent includes binders such as sodium silicate (water glass) and varnish, and inorganic substances such as silica and diatomaceous earth fine powder, as long as the effects of the present invention are not impaired. Etc. can be included.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples.

[Manufacture of cork powder]
The equipment and raw materials used are as follows.
<Crusher>
Dry jet crusher: manufactured by Seishin Corporation, STJ-200 (trademark)
<Particle size measuring device>
Laser diffraction / scattering type particle size distribution analyzer: LMS-30 (trademark) manufactured by Seishin Enterprise Co., Ltd.
<Raw material>
Natural cork powder: manufactured by Nagayanagi Industry Co., Ltd., 200A (trademark), average particle size: 60 μm, particle size range: about 10 to 200 μm

(Production of cork powder having an average particle size of 50 μm, 40 μm and 30 μm)
The raw natural cork powder was pulverized in the dry jet pulverizer to produce cork powder having each average particle size. The raw material charges to the pulverizer were all 10 kg, and the raw material supply pressure was 0.7 MPa. In addition, cork powders having an average particle size of 50 μm, 40 μm, and 30 μm were manufactured at pulverization pressures of 1.0 MPa, 0.7 MPa, and 0.35 MPa, respectively. Table 1 shows the particle size range of each cork powder having an average particle size of 50 μm, 40 μm, and 30 μm and the raw natural cork powder, the cumulative value of particles having a particle size of 100 μm or more, and the cumulative value of particles having a particle size of 10 μm or less. The average particle size and the particle size range are measured by the laser diffraction / scattering particle size distribution analyzer. Each cumulative value is measured using a sieve having openings of 100 μm square and 0 μm square.

(Adjustment of cumulative value of particle size 100μm or more)
The cork powder having each average particle diameter produced as described above was fractionated into a particle diameter of 100 μm or less and a particle diameter of 100 μm or more using a sieve having an opening of 100 μm square. Here, the particle size on the sieve was 100 μm or more, and the particle size on the sieve was 100 μm or less. Subsequently, both samples were collected and mixed so that the accumulated value of particle diameters of 100 μm or more was a predetermined mass%, and each sample was prepared. Here, for the cork powder having an average particle size of 40 μm, due to the shortage of cork particles having a particle size of 100 μm or more, and for the cork powder having an average particle size of 30 μm, due to the total amount of cork particles having a particle size of 100 μm or more, A sample was prepared using cork particles having a particle diameter of 100 μm or more obtained by sieving the raw natural cork powder. When collecting each particle, each of the separated particles was mixed well so that an average particle could be collected, and then a conic quadrant method was used according to JIS Z8816.

(Adjustment of cumulative value of particle size of 10 μm or less)
In the same manner as described above, a sieve having an aperture of 10 μm was used to separate into a particle size of 10 μm or less and a particle size of 10 μm or more. Here, the sieve size was set to 10 μm or less, and the sieve size was set to 10 μm or more. Next, both samples were collected and mixed so that the cumulative value of particle size of 10 μm or less was a predetermined mass%, and each sample was prepared. When collecting each particle, average particles were collected in the same manner as described above.

[Manufacture of release agent]
45 g of the cork powder obtained as described above and 500 ml of water were mixed, and then stirred at room temperature for about 10 hours to thoroughly disperse the cork in water to prepare liquid A. Separately, 15 grams of hydrophilic fumed silica (manufactured by Nippon Aerosil Co., Ltd., AEROSIL200 (trademark)) and 500 ml of water are mixed and dispersed well so that no fumed silica lump remains. Liquid B was produced by leaving it for 10 hours. Next, the total amount of the liquid A and the total amount of the liquid B were mixed and stirred at room temperature for about 10 hours. Next, 40 grams of sodium silicate was mixed with the mixed solution and further stirred at room temperature for about 10 hours to produce a release agent.

[Applying mold release agent to mold]
The mold release agent obtained as described above was spray-applied uniformly using a spray gun so that a cork layer of about 0.1 mm was formed on the entire mold surface previously maintained at 200 ° C. Next, in order to make the lead alloy hot water easily flow to the lattice forming part of the mold, the release agent is further sprayed uniformly only on the outer frame part of the lattice forming part, and the cork layer of the outer frame part The total thickness was about 0.3 mm.

[Casting lattice]
A calcium lead alloy lattice body having a width of 285 mm, a height of 130 mm and a thickness of 1.45 mm was cast using the mold produced as described above and coated with a release agent. The mold temperature during casting was 200 ° C, and the molten metal temperature was 600 ° C. The mass of the manufactured grid was about 90 grams. Next, a calcium lead alloy lattice was cast using the same mold and under the same conditions, and the mass of the produced lattice was measured. This operation was repeated until the mass of the manufactured grid was 100 grams or more. The operation of repeatedly manufacturing the grid body involves pouring the molten metal into the mold, visually confirming that the molten metal accumulated in the gate has solidified, taking out the completed grid body from the mold, and then pouring the molten metal into the mold again. This was done by repeating. Therefore, if the time required for solidification of the molten metal fluctuates, the time required for one cycle of manufacturing the lattice also varies. In the following Tables 2 to 5, the number of cast surfaces refers to the total number (surfaces) of the lattice bodies produced as described above, and the casting time refers to the time required to produce the entire lattice body [ Time]. Moreover, comprehensive evaluation was judged from the number of casting surfaces and casting time, and each symbol in a table | surface means (circle): very favorable, (DELTA): favorable, and x: defect.

[Examples 1-4 and Comparative Examples 1-3]
Using the above natural cork powder 200A (trademark) having an average particle diameter of 60 μm, the cumulative values of particle diameters of 100 μm or more as described above are 20% by mass, 15% by mass, 10% by mass, 5% by mass, Seven types of cork powders were produced by adjusting the content to 2% by mass, 1% by mass, and 0% by mass. In the cork powder, the cumulative value with a particle size of 10 μm or less was 0% by mass. Using the cork powder, a release agent was produced as described above and applied to a mold. A grid was manufactured using the mold. The results are shown in Table 2.

In Examples 1 to 4, a cork powder having an average particle diameter of 60 μm was used, and the cumulative value of particle diameters of 100 μm or more was changed within the scope of the present invention. All showed good casting time and number of cast surfaces. In Examples 1 to 3, the casting time and the number of cast surfaces tended to increase as the cumulative value of particle sizes of 100 μm or more increased. In Example 4, although the casting time and the number of casting surfaces were slightly reduced as compared with Example 3, the effect of the present invention could be sufficiently exhibited.

On the other hand, Comparative Examples 1-3 used the cork powder with an average particle diameter of 60 micrometers, and made the cumulative value with a particle diameter of 100 micrometers or more out of the range of this invention. Comparative Example 1 does not include particles having a particle size of 100 μm or more. Compared to Example 1, a stronger cork layer was formed and the casting time was increased. However, the heat insulating property of the cork layer was increased more than necessary, and the solidification time of the melt became longer. As a result, the time required for one cycle of manufacturing the lattice body was increased, and the number of cast surfaces was reduced. In Comparative Examples 2 and 3, the cumulative value of the particle size of 100 μm or more exceeded the range of the present invention. In the operation of repeatedly producing the lattice body, the cork layer dropped out, and as a result, the casting time and the number of cast surfaces were significantly reduced.

[Examples 5 to 8]
Cork powder having an average particle size of 50 μm produced as described above was used. First, in the same manner as in Example 3, adjustment was made so that the cumulative value of particle diameters of 100 μm or more was 5% by mass. Next, the cumulative values of particle diameters of 10 μm or less were adjusted to 0 mass%, 5 mass%, 10 mass%, and 15 mass%, respectively. Using the cork powder, a release agent was produced as described above and applied to a mold. A grid was manufactured using the mold. The results are shown in Table 3.

[Examples 9 to 12]
The cork powder having an average particle size of 40 μm produced as described above was used, and the cumulative values of the particle size of 10 μm or less were adjusted to 0 mass%, 5 mass%, 10 mass%, and 15 mass%, respectively. Except for this, the same procedure as in Example 5 was performed. However, when adjusting so that the cumulative value of the particle size of 100 μm or more is 5% by mass, the particle size of 100 μm or more obtained by sieving the raw material natural cork powder with the particle size of 100 μm or more of the shortage Replenished from cork particles. The results are shown in Table 4.

[Examples 13 to 16]
The cork powder having an average particle size of 30 μm produced as described above was used, and the cumulative values of the particle size of 10 μm or less were adjusted to 0 mass%, 5 mass%, 10 mass%, and 15 mass%, respectively. Except for this, the same procedure as in Example 5 was performed. However, when adjusting so that the cumulative value of particle size of 100 μm or more is 5% by mass, cork particles of particle size of 100 μm or more obtained by sieving the raw natural cork powder as particles of particle size of 100 μm or more used. The results are shown in Table 5.

In each of Examples 5 to 8, a cork powder having an average particle size of 50 μm was used, the cumulative value of particle size of 100 μm or more was adjusted to 5 mass%, and the cumulative value of particle size of 10 μm or less was 0 mass respectively. %, 5% by mass, 10% by mass and 15% by mass. Example 5 was the same as the result of Example 3 in which cork powder having an average particle diameter of 60 μm was used and the cumulative value of particle diameters of 100 μm or more was 5% by mass, and the casting time and the number of cast surfaces were good. . In Example 6, although the casting time was not much different from Example 5, the number of casting surfaces was remarkably increased. It has been found that when the cumulative value of the particle size of 10 μm or less is changed from 0 mass% to 5 mass%, the number of cast surfaces can be remarkably increased. In Example 7, in which the cumulative value of the particle size of 10 μm or less was larger than that in Example 6, the number of cast surfaces was further increased remarkably. In Example 8, the casting time was almost the same as in Examples 5 and 6. Although the number of cast surfaces was somewhat reduced, the effect of the present invention was not impaired.

Examples 9 to 12 all use cork powder with an average particle size of 40 μm, adjust the cumulative value of particle size of 100 μm or more to 5% by mass, and set the cumulative value of particle size of 10 μm or less to 0% by mass, respectively. %, 5% by mass, 10% by mass and 15% by mass. In Example 9, the casting time and the number of casting surfaces were slightly increased as compared with Example 5 in which cork powder having an average particle diameter of 50 μm was used. In Examples 10 and 11, the casting time and the number of cast surfaces increased significantly. On the other hand, in Example 12, in which the cumulative value of the particle size of 10 μm or less was further increased from that in Examples 10 and 11, the casting time and the number of cast surfaces were reduced. However, the effect of the present invention can be sufficiently exhibited.

In each of Examples 13 to 16, a cork powder having an average particle size of 30 μm was used, the cumulative value of particle size of 100 μm or more was adjusted to 5% by mass, and the cumulative value of particle size of 10 μm or less was 0 mass respectively. %, 5% by mass, 10% by mass and 15% by mass. Example 13 had the same casting time and number of casting surfaces as Example 9 using cork powder having an average particle size of 40 μm. In Examples 14 and 15, the casting time and the number of casting surfaces were remarkably increased as in the case of the average particle size of 40 μm. On the other hand, in Example 16, in which the cumulative value of the particle size of 10 μm or less was larger than those in Examples 14 and 15, the casting time and the number of cast surfaces were reduced. However, the effect of the present invention can be sufficiently exhibited.

From the results of the above examples and comparative examples, the casting time and the number of casting surfaces of the lattice body are remarkably increased by setting the cumulative value of the particle size of 100 μm or more of the cork powder used as the release agent to 1 to 10% by mass. It turns out that it can be made. Moreover, it turned out that the casting time and the number of casting surfaces of a grid | lattice body can be further increased notably by making the cumulative value of a particle size 10 micrometers or less into 5 mass% and 10 mass%. In addition, it became clear that the casting time and the number of cast surfaces of the lattice body were remarkably good when the average particle size of the cork powder was in the range of 30 μm to 50 μm.

The cork powder-containing release agent of the present invention can produce an extremely homogeneous electrode plate lattice with extremely high productivity when casting an electrode plate lattice used in a lead-acid battery. Therefore, it is useful for inexpensively and efficiently producing a high-quality, high-performance lead-acid battery.

Claims (3)

In the cork powder-containing mold release agent used for casting the grid for lead-acid battery electrode plates, the mold release agent is characterized in that the cumulative value of particles having a particle size of 100 μm or more in the cork powder is 1 to 10% by mass. The mold release agent according to claim 1, wherein the cork powder has an average particle size of 30 to 50 µm and a cumulative value of particles having a particle size of 10 µm or less in the cork powder is 1 to 10% by mass. The release agent according to claim 1 or 2, wherein a cumulative value of particles having a particle diameter of 10 µm or less in the cork powder is 5 to 10% by mass.