JP2001303287A - Pole plate for electrolytic refining of zinc - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulating protector which is welded to a pole plate for electrolytic refining of zinc and is excellent in adhesiveness, water resistance and acid resistance by blending denatured polyolefin. SOLUTION: In the pole plate for electrolytic refining of zinc in which the insulating protector is welded onto an end edge of the pole plate made of aluminum, the insulating protector is a mixture of the denatured polyolefin formed by copolymerization of a polyolefin and an unsaturated carboxylic acid and the denatured polyolefin formed by copolymerization of the polyolefin and an unsaturated carboxylic acid derivative.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode plate for electrolytic refining of zinc, and more particularly to an electrode plate for electrolytic refining of zinc in which an insulating protective body is fused to an edge of an electrode plate made of aluminum.

[0002]

2. Description of the Related Art In an electrode plate for electrolytic refining of zinc, an insulating strip (insulating protective body) is provided on a peripheral edge of the electrode plate where phenomena such as zinc precipitation and aluminum corrosion are particularly likely to occur. It is known to prevent the above disadvantageous phenomena, and it is also known to use a copolymer polyolefin resin, for example, a copolymer of a polyolefin and an aliphatic carboxylic acid, as the insulating protective material. (See Japanese Patent No. 2596648).

[0003]

However, even when a copolymer polyolefin resin is used as in the above-mentioned prior art, when the copolymer polyolefin is a simple substance,
It was confirmed by experiments by the inventors that none of them could secure sufficient adhesive strength, water resistance and acid resistance, and they did not satisfy the insulation protection function of the electrode plate for electrolytic refining. In other words, some copolymer polyolefins have low adhesion to aluminum plates, and other copolymer polyolefins have high initial adhesion, but hydrolyze when immersed in sulfuric acid, an electrolyte. It was confirmed that the adhesion strength was remarkably reduced. On the other hand, the present inventors have confirmed that even with a polyolefin resin, it is possible to secure the adhesiveness and water resistance / acid resistance of the insulating protective body by mixing a plurality of copolymers or by a structural combination. .

The present invention has been made in view of the above circumstances, and is directed to an insulating protective body to be welded to an electrode plate for electrolytic refining of zinc, which is excellent in adhesiveness, water resistance and acid resistance by mixing a modified polyolefin. The purpose is to provide. Also,
Another object of the present invention is to improve the adhesiveness and the resistance to water and acid by the arrangement structure of the insulating protective body.

[0005]

According to the present invention, there is provided an electrode plate for electrolytic refining of zinc in which an insulating protective member is fused on an edge of an electrode plate made of aluminum. A modified polyolefin obtained by copolymerizing an unsaturated carboxylic acid (hereinafter referred to as a first modified resin) and a modified polyolefin obtained by copolymerizing a polyolefin and a derivative of an unsaturated carboxylic acid (hereinafter referred to as a second modified resin) It is a mixture (claim 1). The polyolefin includes ethylene, propylene, 1-butene,
An α-olefin homopolymer or copolymer such as 1-pentene, or a mixture of these polymers is used.

[0006] The first modified resin has a lower adhesive strength than the second modified resin, but has better water resistance and acid resistance than the second modified resin. Examples of the unsaturated carboxylic acid forming the first modified resin include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid. Also, the second modified resin is
Although the initial adhesive strength is high, the adhesive strength is greatly reduced due to hydrolysis that occurs when the joint surface with the electrode plate comes into contact with the electrolytic solution. Derivatives of the unsaturated carboxylic acid forming the second modified resin include acid anhydrides such as maleic anhydride and citraconic anhydride, such as ester-based methyl acrylate and butyl methacrylate, amide-based acrylamide, and maleic acid monoamide. And metal salt-based sodium acrylate such as imide-based maleimide. The modification rates of the first modified resin and the second modified resin can be adjusted by a known method. However, in the present invention, when the modification rate is less than 5%, a predetermined adhesive strength cannot be obtained, and %, The adhesive strength is not increased for the cost. Therefore, the one in the range of 5 to 50%, more preferably in the range of 11 to 30% is used.

According to the mixture of the first modified resin and the second modified resin, the adhesive strength is mainly ensured by the second modified resin, and the water resistance and the acid resistance are reinforced by the first modified resin, so that the mixture can be used during refining. Adhesive strength is ensured.

[0008] The insulating protective body of the present invention may be a mixture of a carboxylic acid having excellent water resistance and acid resistance in addition to the first modified resin and the second modified resin. ). Palmitic acid, myristic acid, and the like are used as the carboxylic acid (hereinafter referred to as an additive) having excellent water resistance and acid resistance, and their adhesive strength is lower than that of the first modified resin. According to the mixture of the first modified resin, the second modified resin, and the additive, the water resistance and the acid resistance of the second modified resin are further reinforced, and a decrease in the adhesive strength during refining can be suppressed. Furthermore, the insulating protective body of the present invention may be a mixture of the second modified resin and the additive (claim 3). According to this, compared with the case where the first modified resin is mixed, Adhesive strength can be increased.

The insulating protective body is fused to the electrode plate while forming the mixture described above into a substantially U-shaped cross section by compression molding, extrusion molding, or injection molding.
It is also characteristic that the second modified resin and the additive have low compatibility with each other and are difficult to mix. By utilizing this fact, the second modified resin, which mainly ensures the adhesive strength, and the first modified resin and / or the additive are bonded to the electrode plate in a state of being uniformly dispersed, and this dispersion state is changed. Thereby, it is possible to adjust the balance between the adhesive strength of the insulating protective body and the resistance to water and acid.

As one of means for adjusting the dispersion state of the mixture, the particle sizes of the first modified resin, the second modified resin, and the additives are made different. For example, a pellet material is used for the second modified resin, and a powder material is used for the first modified resin and the additive, so that the second modified resin is uniformly dispersed. As another means, the first modified resin, the second modified resin, the MFR (melt flow rate) of the additive, the molding temperature or the molding method may be changed. The molding method may be compression molding or extrusion molding, Any of injection molding may be used.
In the case of compression molding, more uniform dispersion is possible, but the production cost is higher.

Further, the present invention can also solve the above-mentioned problems by an arrangement structure of an insulating protective body and the additive having excellent water resistance and acid resistance. That is, an arrangement structure in which the electrolytic solution (sulfuric acid) does not intrude into the joint surface between the insulating protective body and the electrode plate, specifically, excellent water resistance and acid resistance at the joint end between the insulating protective body and the electrode plate. A configuration in which carboxylic acid (the above-mentioned additive) is interposed in a fused state as a seal layer (claims 4 and 5). In that case, the insulating protection body is the first
Although a mixture of the modified resin and the second modified resin may be used (claim 5), the sealing property to the joint surface between the insulating protective body and the electrode plate is strengthened, so that the insulating protective body is second modified. Only resin may be used (claim 4).

In view of the fact that the first modified resin and the second modified resin are costly, the insulating protective body is made of an insulating protective layer having the above-mentioned improved adhesive strength and water and acid resistance as an insulating inner layer. It is preferable that the outer layer has a two-layer structure in which ordinary polyolefin is applied (claim 6). In this case, the insulating inner layer has a thickness of about 0.1 to 1.0 mm, and the outer layer has a thickness of 1.0 to 1.0 mm. To about 5.0 mm.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described. FIG. 1 shows an outline of a conventionally known electrolytic cell 1 for electrolytic refining of zinc, and reference numeral 2 in the figure denotes a sulfuric acid solution. Electrolyte, 3 is an electrode plate (cathode plate) made of aluminum, 4 is an electrode plate holding device, and 5 is a conductor rail. Electrode plate 3
The insulating protective body 10 of the present invention is attached by fusing to the left and right sides or both the left and right sides and the bottom side of the part immersed in the electrolyte 2. The electrode plate 3 is configured such that the edge 3b is
a, which is thinner than a (FIGS. 2, 3, 4 (1),
5), and as shown in FIG. 4 (2), there is a case where it is formed to have the same thickness as the main body portion 3a, and the insulating protection body 10 having a substantially U-shaped cross section is fitted to the edge 3b. It fuses together. Although not shown, in the case of FIGS. 2, 3 and 5, the edge 3b may have the same thickness as the main body 3a as in FIG. 4 (2). When the edge 3b is formed to be thinner than the main body 3a, it is preferable to attach the insulating protective body 10 and the main body 3a of the electrode plate 3 so as to be flush as shown in the figure.

Since the insulating protective body 10 includes a plurality of embodiments having different mixed compositions, for convenience, reference numerals 10a to 10e,
Description will be made with reference to 11a to 11e. Insulation protection body 10a
Is a mixture of the first modified resin and the second modified resin described above,
Specifically, a copolymer of polyethylene and methacrylic acid was selected as a first modified resin example, and a copolymer of polyethylene and maleic anhydride was selected as a second modified resin example. It is a mixture of polymers (FIG. 2). The insulating protective body 10b is obtained by further mixing the mixed composition of the insulating protective body 10a with a palmitic acid selected as an example of an additive, that is, a copolymer of polyethylene and methacrylic acid, and a copolymer of polyethylene and maleic anhydride. It is a mixture of a polymer and palmitic acid (FIG. 2). The insulating protective body 10c is a mixture of the second modified resin example and the additive example, that is, a mixture of a copolymer of polyethylene and maleic anhydride and palmitic acid (FIG. 2).

The insulating protective body 11a is provided with the insulating protective body 10a.
a having an insulating cover layer 11 on the outer surface thereof, and an insulating protector 11b having a two-layer structure in which the insulating cover layer 11 is provided on the outer surface of the insulating protector 10b.
Has a two-layer structure in which an insulating jacket layer 11 is applied on the outer surface of the insulating protection body 10c (FIG. 3). The insulating jacket layer 11
The purpose of the present invention is to reduce the amount of use of the insulating protection members 10a, 10b, and 10c.
10c functions as an adhesive layer and an insulating layer, and the insulating outer layer 1
1 mainly has the function of an insulating layer. This insulating coating layer 1
For 1, an ordinary polyolefin, specifically, polyethylene is used.

The insulating protective body 10d is provided on the main body 3a of the electrode plate 3.
The above-mentioned additive example (paltimic acid) is applied to the side end face of the sealing layer 12.
And then fused to the edge 3b.
This is a modified resin example, that is, a structure in which a copolymer of polyethylene and maleic anhydride is fused and arranged (FIG. 4).
The insulating protective body 10e is one in which the insulating protective body 10a, that is, a mixture of the first modified resin and the second modified resin is disposed instead of the second modified resin example (FIG. 4). The insulating protective body 11d is obtained by attaching an insulating covering layer 11 on the outer surface of the insulating protective body 10d.
Is obtained by applying an insulating coating layer 11 on the outer surface of the insulating protective body 10e (FIG. 5). The edge 3b of the electrode plate 3 and the insulating protective body 10d or 1
The sealing property of the joining surface with 0e, that is, infiltration of the electrolytic solution 2 into the joining surface is prevented.

An example for confirming the adhesive strength will be described below. In addition, since the adhesive characteristics of the insulating protective bodies 10a to 10e have the same tendency as the characteristics of the insulating protective bodies 11a to 11d, examples of the insulating protective bodies 11a to 11e will be described. (Example 1) Regarding the insulating protective body 11a, the first modified resin example (copolymer of polyethylene and methacrylic acid) 50 parts (MFR10 (g / 10 minutes), melting point 94 ° C, modification rate 12%, pellet) 2 Modified resin example (copolymer of polyethylene and maleic anhydride) 50 parts (MFR 0.4 (g / 10 min), melting point 122 ° C., modification rate 25%, pellets) were mixed and melted, and polyethylene (MFR1 .1 (g
/ 10 min), melting point 131 ° C., 100 parts of pellets) are similarly melted. They are extruded by the simultaneous two-layer molding method to produce the insulating protection body 11a (see FIG. 6).
In addition, the thickness of the insulating cover layer 11 is 1.2 m.
m, and the thickness of the inner layer (insulating protective body 10a) was made 0.4 mm (the same applies to the following). A part of the insulating protective body 11a was cut out into a test piece 11a ', which was placed on and bonded to a test piece 3' made of the same material as the electrode plate 3 subjected to the degreasing and cleaning treatment. The bonding conditions were 200 ° C. and 44.1 kPa (0.45 kgf / c
m ² ) for 1 minute. The result of the 180 degree peel test was that the initial adhesive strength was 137 (N / 15 mm),
Adhesive strength over time: 131 (N / 15 mm). In addition,
The time-dependent adhesive strength is obtained by performing a peel test under the same conditions after immersion in a 20% sulfuric acid solution (20 ° C.) for 72 hours (the same applies to the following Examples and Comparative Examples).

Example 2 Regarding the insulating protective body 11b, 30 parts of a first modified resin example (copolymer of polyethylene and methacrylic acid) (MFR10 (g / 10 minutes), melting point 94 ° C., modification rate 12%, Pellet) Second modified resin example (copolymer of polyethylene and maleic anhydride) 67 parts (MFR 0.4 (g / 10 min), melting point 122 ° C., modification rate 25%, pellet) Palmitic acid (melting point 62.65) 3 ° C., powder) and mixed and melted with polyethylene (MFR1.1 (g
/ 10 min), melting point 131 ° C., 100 parts of pellets) are similarly melted. They are extruded by the simultaneous two-layer molding method to produce the insulating protection body 11b. The test piece of the insulating protection body 11b was placed on and bonded to the test piece of the electrode plate 3 under the same bonding conditions as in Example 1. The result of the 180 degree peel test was that the initial adhesive strength was 134 (N / 15
mm), adhesive strength with time: 132 (N / 15 mm).

Example 3 Regarding the insulating protective body 11c, 97 parts of a second modified resin example (copolymer of polyethylene and maleic anhydride) (MFR 0.4 (g / 10 min), melting point 122 ° C., modification rate) 25%, pellets) 3 parts of palmitic acid (melting point 62.65 ° C, powder) were mixed and melted, and polyethylene (MFR1.1 (g
/ 10 min), melting point 131 ° C., 100 parts of pellets) are similarly melted. They are extruded by the simultaneous two-layer molding method to produce the insulating protection body 11c. The test piece of the insulating protection body 11c was placed on and bonded to the test piece of the electrode plate 3 under the same bonding conditions as in Example 1. The result of the 180 degree peel test was that the initial adhesive strength was 145 (N / 15
mm), and the adhesive strength with time was 143 (N / 15 mm).

(Embodiment 4) Regarding the insulating protection body 11d,
In order to confirm the adhesive strength, test pieces having substantially the same arrangement structure as shown in FIG. 7 were prepared. That is, the second modified resin example (copolymer of polyethylene and maleic anhydride) (MFR 0.4 (g / 10 minutes), melting point 122 ° C., modification rate 25%, pellets) was melted, and polyethylene (MFR1 .3 (g / 10 min), melting point: 120 ° C., pellets) are similarly melted, and extruded by a simultaneous two-layer molding method to produce a test piece 11 d ′ of an insulating protective body. On the other hand, a seal layer 12 ′ made of palmitic acid is previously fused to both sides of the test piece 3 ′ of the electrode plate 3, and the second modified resin example 13 is located between the two seal layers 12 ′. Then, the test piece 11d 'was placed thereon and bonded under the same bonding conditions as in Example 1. The result of the 180 degree peel test was that the initial adhesive strength was 145 (N / 15 mm),
Adhesion over time was 145 (N / 15 mm).

Example 5 In Example 4, instead of the second modified resin example 13, a mixture 10a of a first modified resin example and a second resin example (see Example 1) was adhered. The result of the 180 degree peel test was that the initial adhesive strength was 14
2 (N / 15 mm), adhesive strength over time: 142 (N / 15
mm).

Next, a comparative example in which each of the first modified resin example and the second modified resin example is used alone will be described. (Comparative Example 1) A first modified resin example (copolymer of polyethylene and methacrylic acid) (MFR10 (g / 10 min), melting point 94 ° C, denaturation) At a rate of 12%, pellets), and polyethylene (MFR 1.3 (g / 10 min), melting point 120 ° C., pellets). They were extruded by a simultaneous two-layer molding method to produce an insulating protective body, and a test piece cut from the protective body was placed on a test piece of an electrode plate on an electrode plate at 170 ° C. and 44.1 kPa (0.45 kgf). / Cm
² ) Bonded for 1 minute. The result of the 180 degree peel test was that the initial adhesive strength was 113 (N / 15 mm),
Adhesive strength over time: 85 (N / 15 mm).

(Comparative Example 2) With respect to the insulating protective body using the second modified resin alone, the second modified resin (copolymer of polyethylene and maleic anhydride) (MFR 0.4 (g
/ 10 min), melting point 122 ° C, denaturation rate 25%, pellet)
Is melted, and polyethylene (MFR1.1 (g / 10
Min), melting point 131 ° C., pellet). They were extruded by a simultaneous two-layer molding method to produce an insulating protective body, and a test piece cut from the protective body was placed on a test piece of an electrode plate, and adhered at 200 ° C., 44.1 kPa.
(0.45 kgf / cm ² ) for one minute. The result of the 180 degree peel test was that the initial adhesive strength was 15
2 (N / 15 mm), Adhesion over time: 16 (N / 15
mm).

As is clear from the comparison between the above example and the comparative example, the insulating protective body of the comparative example has a remarkably reduced adhesive strength with time with respect to the initial adhesive strength. Although the decrease in the adhesive strength was remarkable, it was confirmed that in the case of the product of the present invention shown in the examples, the decrease in the adhesive strength with time was slight.

[0025]

According to the electrode plate for electrolytic refining of the present invention, the insulating protective body is composed of a copolymer of polyolefin and unsaturated carboxylic acid or a copolymer of polyolefin and unsaturated carboxylic acid derivative alone. Unlike the case, the copolymer of the polyolefin and the derivative of the unsaturated carboxylic acid ensures the main adhesive strength, and the copolymer of the polyolefin and the unsaturated carboxylic acid and / or the water- and acid-resistant carboxylic acid Water and acid resistance are reinforced by the mixing of. Therefore, when the electrode plate is immersed in the electrolytic solution (sulfuric acid solution) during electrolytic refining, it is possible to suppress the adhesive property from being significantly reduced due to hydrolysis, and to maintain a high adhesive strength and to insulate the electrode plate It is possible to secure the protection function and perform the electrolytic refining process with high productivity.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an outline of an electrolytic cell for electrolytic refining of the present invention.

FIG. 2 is a cross-sectional view taken along (2)-(2) of the electrode plate in FIG.

FIG. 3 is a sectional view showing another embodiment of the electrode plate.

FIG. 4 is a cross-sectional view showing still another embodiment of the electrode plate. (2) is a partial sectional view showing another embodiment of the electrode plate shape.

FIG. 5 is a sectional view showing still another embodiment of the electrode plate.

FIG. 6 is an explanatory diagram of a test piece manufactured as an insulating protection body.

FIG. 7 is a sectional perspective view showing another test piece.

[Explanation of symbols]

3: Electrode plate (cathode plate) 3a: Main body
3b: Edge 10: Insulating protective body 10a to 10e: Insulating protective body 11a to 11e: Insulating protective body 11: Insulating jacket 12: Seal layer

Claims (6)

[Claims] 1. A zinc electrolytic refining electrode plate in which an insulating protective body is fused to an edge of an aluminum electrode plate, wherein the insulating protective body is obtained by copolymerizing a polyolefin and an unsaturated carboxylic acid. An electrolytic zinc refining electrode plate comprising a mixture of a modified polyolefin and a modified polyolefin obtained by copolymerizing a polyolefin and a derivative of an unsaturated carboxylic acid. 2. The electrode plate for electrolytic refining of zinc according to claim 1, wherein said insulating protective body is a mixture further containing a carboxylic acid having water resistance and acid resistance. 3. An electrode for electrolytic refining of zinc in which an insulating protective body is fused to an electrode plate made of aluminum, wherein the insulating protective body is made of a modified polyolefin obtained by copolymerizing a derivative of a polyolefin and an unsaturated carboxylic acid. An electrode for electrolytic refining of zinc, which is a mixture with a carboxylic acid having water resistance and acid resistance. 4. An electrode plate for electrolytic refining of zinc in which an insulating protective body is fused on an edge of an electrode plate made of aluminum, wherein the insulating protective body copolymerizes a polyolefin and a derivative of an unsaturated carboxylic acid. Modified polyolefin,
An electrode plate for electrolytic refining of zinc, characterized in that a sealing layer made of a carboxylic acid having water resistance and acid resistance is interposed in a fused state at a joint end portion between the insulating protective body and the electrode plate. 5. The electrode plate for electrolytic refining of zinc according to claim 4, wherein the insulating protective body is the mixture according to claim 1. 6. The electrolytic refining of zinc according to any one of claims 1 to 5, wherein the insulating protective body is constituted by applying an insulating jacket layer made of a normal polyolefin on the surface of the mixture. Electrode plate.