JPH01258355A - External can for dry cell - Google Patents

Abstract

PURPOSE:To ensure the complete coverage of a seam part and improve adhesion by applying a correction coat in such a way that the coat and the like applied to both side edge parts at the butt position of an external can for dry cell are removed by the predetermined width before welding and the correction coat is so applied to the external surface of the welded part as to give the required film thickness over the width larger than the the seam width by the predetermined size. CONSTITUTION:Both ends of the metal plate 3 of an external can 1 for a dry cell are connected to each other at a weld seam 2 and a cylindrical form is thereby obtained. A paint 4 applied to the external surface of the metal plate 3 of the can 1 via a printing process and the like is removed from the ends 3a and 3b over the width of 0.5 to 3mm. Also, a correction paint 6 of 5 to 30mum thick film is applied to the external side of the weld part over the width larger than the width of the seam 5 by 1.0 to 8 mm. By applying the correction paint 6 to the weld part, the occurrence of rust and corrosion at the time of laser beam welding is prevented and the coverage of the seam 5 is made com plete and superior in adhesion.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a laser welding can, and more specifically, the generation of soot during laser welding is prevented, and the negative effects caused by the generation of soot are eliminated. The present invention relates to an exterior can for a dry battery, in which the correction paint applied to the welded portion is complete and has excellent adhesion.

(Prior art and its problems) Conventional outer cans for dry batteries are made by forming a surface-treated steel plate such as tinplate or tin-free steel (TFS) into a cylindrical shape, and joining both edges of the can with solder, adhesive, etc. The former case, which uses solder or adhesive, requires a considerable area to form the joint.
There is a problem in terms of saving resources, and since there is a considerable step at the side seam, there is a problem that leakage often occurs at the step when both ends are tightened.

As for the latter type of welded exterior cans, those made by resistance welding are widely used, and in this case, even if it is a lap seam can, the seam area is smaller than the former, but
Satisfactory results have not been obtained for small cans such as outer cans for dry batteries.)

Laser welding is known to solve this problem, but when laser welding is used to form outer cans for dry batteries, when the laser beam is irradiated to the welding position of the metal plate, the polymer compound applied to the metal plate There is a problem in that the paint and other materials burnt and soot is generated. This generated soot adheres to the vicinity of the welding position, impairing the appearance of the can, and adheres to the optical lens of the laser irradiation device.Furthermore, some of the generated soot melts into the molten metal plate. There is a problem in that the welding strength decreases due to this, and it is necessary to leave the area to be welded free of paint or the like.

For this reason, in the past, when printing designs etc. on large metal plates, they were printed at several intervals to avoid applying paint, etc. to the areas to be welded, but some exterior cans for dry batteries small,
Since several hundred cans are taken from a large metal plate, there is a problem in that errors occur during cutting.

Furthermore, in the case of a seam in which bare metal is exposed without being coated with paint or the like, it is necessary to coat the joint with an organic resin in order to prevent rust and corrosion.

Therefore, an object of the present invention is to provide an exterior can for a dry cell in which the generation of soot during laser welding is prevented, the adverse effects caused by this are eliminated, and the generation of rust and corrosion are also prevented.

(Means for Solving the Problems) According to the present invention, the edges of both sides of metal plates, which have been coated with paint or the like on at least one of the surfaces or inner surfaces, are butted together, and the butted positions are laser welded. In the outer can for dry batteries, the paint etc. applied to the edge parts on both sides at the butting position are 0.5 to 3 mm from the edge parts respectively.
The width of the joint is removed before welding, and the outer surface of the weld area is coated with correction paint to a thickness of 5 to 30 μm over a width of 1 to 8 mrrr larger than the width of the seam. An exterior can for a dry battery is provided.

(Function) In FIG. 1 showing the entire exterior can for a dry battery of the present invention, the exterior can for a dry battery 1 has a cylindrical shape in which metal plates are joined together by a welded seam 2.

In FIG. 2, which is an enlarged sectional view of the welded part 2 of the outer can for a dry battery according to the present invention, ink or paint 4 is applied by printing or the like on the outer surface side of the metal plate 3; Part 3
In a and 3b, the ink and paint have been removed from the ends thereof over a distance of 60.5 to 3 mt, particularly 1 to 2 mm (indicated by Wl in FIG. 2).

The width of the welding area from which this ink and paint has been removed is larger than the spot diameter of the laser beam during the laser welding process. Since the laser beam is not irradiated to the area, the generation of soot due to ink etc. is prevented.

When removing ink, etc. from the edges of the metal that are to be welded, remove the edges by approximately 1m+w to create a space for printing.)
Although it is possible to easily remove it by scraping it off with a hard member, it is not limited to this method (although various other methods can be adopted).

Laser welding makes it possible to reduce the area of the welded part by taking advantage of the property that the laser beam is a coherent light that can be focused on a minute spot and obtain a locally extremely high energy density. This is what I did. In other words, when a laser beam is irradiated to the butt position of both ends of the metal plate, the minute portion at the end of the metal plate melts.
They are glued together.

Compared to conventional welding methods, seam formation using laser welding causes the welded part to protrude less to the inside and outside of the can, so it is not possible to use unit cells using zinc cans, which are larger due to this difference in thickness. , it becomes possible to increase the capacity of the battery.

As the laser welding method, various conventionally known methods can be used, but for example, US Pat. No. 4,152,573
Like the device described in the specification, the two ends of the metal plate are brought together, and the fixed laser irradiation device and the area to be welded face each other, and the can is moved along the seam direction while the laser is applied. An example of this method is to irradiate. In this case, it is necessary to remove paint, etc. from both ends of the metal plate before installing the metal plate in this device, but it goes without saying that removing the paint, etc. and welding the joints can be done in the same device. stomach.

In the present invention, the bare metal is exposed at the seam 5 of the can immediately after welding, and if left as is, rust and corrosion will occur, so it is necessary to apply a correction paint 6 to the outer surface of the seam. It is also important that the thickness of this correction paint (indicated by h in Figure 2) is within the range of 5 to 30 μm, especially 7 to 20 μm; if this thickness is smaller than the above range, metal corrosion may be prevented and rust may occur. It is unsatisfactory in terms of prevention, etc., and if it is larger than the above range, it is economically disadvantageous and
When a polymerizable paint is used, the polymerization rate decreases, resulting in a decrease in the physical properties of the coating and its barrier properties against corrosive components.

In addition, this correction paint is applied on the printing ink, paint, etc. applied to the metal plate with a thickness of 0.5 to 2 mm, especially 1 to 1.5 m.
It is also important to apply the coating layer m (indicated as W2 in FIG. 2) in multiple layers. If the overlapping portion is less than the above range, the metal is likely to be exposed, which is unfavorable from the viewpoint of preventing rust and corrosion, while if it is more than the above range, it is only economically disadvantageous.

In the outer can for dry cell batteries of the present invention, it is preferable to provide a notch as shown at 7 in FIG. 1. Laser welded cans have extremely strong tensile strength in the radial direction, If it is used incorrectly, such as during charging, or left in a high-temperature atmosphere of 85° C. or higher, it may expand in the height direction and the sealing plate integrated with the upper anode cap may come off.

It is desirable to provide this notch 7 in order to release the pressure in the height direction that occurs in such a case.

(Preferred embodiment of the invention) As the metal plate constituting the Kuramasa Tsuta welded can, a known metal plate for cans, particularly a surface-treated steel plate, is used, such as a tin-plated steel plate (tinplate), a nickel-plated steel plate, a tin-plated steel plate, etc. - Examples include nickel-plated steel sheets, tin-free steel (electrolytic chromic acid treated steel sheets), etc. Among these, the surface-treated steel sheet with excellent welding workability is tinplate, and the amount of tin plating is generally 1 to 12 g/m", especially 2.8 to 5.6 g/m".
Those within the range are advantageously used. The thickness of the metal plate varies depending on the use of the can, but when used as an exterior can for dry batteries, a thickness within the range of 0.1 to 0.25 mm is generally used.

A protective coating film known per se can be provided on the surface of the metal plate that will become the inner surface of the can or the outer surface of the can, and this protective coating can be any paint made of thermoplastic or thermosetting resin:
Modified epoxy paints such as phenol-epoxy paints and amino-epoxy paints: for example, vinyl chloride-vinyl acetate copolymers, partially saponified vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinyl acetate-maleic anhydride copolymers Vinyl or modified vinyl paints such as , epoxy-modified, epoxyamino-modified, or epoxyphenol-modified vinyl resin paints, acrylic resin paints, and synthetic rubber paints such as styrene-butadiene copolymers are used.

The thickness of the coating is generally 2 to 20 μm, especially 3 to 15 μm.
Preferably, it is in the μm range.

As the correction paint used in the present invention, it is possible to use the above-mentioned protective paint as a correction paint, but from the viewpoint of the adhesion of the paint film, in particular, a liquid polymerizable composition containing a photoinitiator is used. Preferably, the product is used as a correction paint.

Since this liquid polymerizable composition containing a photoinitiator is a liquid, it has the characteristic that it can uniformly wet the entire surface of the welding area, including minute irregularities and splash areas, and uniformly cover the welding surface. has.

In addition, this liquid composition has the characteristic that it is cured by ultraviolet irradiation in the liquid coated state, so there is no need for heating, and the polymerization and curing proceeds while maintaining the viscosity at the time of initial application. Therefore, problems such as exposure of the bare metal due to the resin component flowing out from the corners and generation of bubbles due to solvent evaporation are also solved.

As the photoinitiator and the liquid polymerizable composition, any known ones can be used as long as the polymerization can be initiated and cured by light. Particularly satisfactory results are obtained by using a bisepoxy prepolymer or a combination thereof with a monoepoxy compound, in which the photoinitiator is a photosensitive diazonium double salt or a photosensitive aromatic onium salt.

As the bis-epoxy monomer or bis-epoxy prepolymer, any compound having substantially two epoxy groups (oxirane rings) at the end of the molecule can be used. Here, "substantially two" means that the main component of the compound used is a bisepoxy compound, and that it is permissible for some monoepoxy compounds and trisepoxy compounds to be included. The monomer or prepolymer used in the present invention has a molecular weight of 100 to 4000, particularly 130 to 2
000 epoxy equivalent weight.

Suitable examples of bisepoxy monomers are:

fi) Bisepoxy compound represented by the general formula, where Y represents an ether (-0-) group or an oxycarbonyl (-0-C-) group, and 2 represents a divalent hydrocarbon group: for example, 1 .4-butanediol glycidyl ether, bisphenol A glycidyl ether, bisphenol F glycidyl ether, phthalic acid glycidyl ester, adipic acid glycidyl ester.

fiil general formula, where R is a hydrogen atom or a methyl group, Y and 2 have the above-mentioned meanings, p is zero or 1, and when p is zero, two Y represent an oxycarbonyl group Bisepoxy compounds represented by: for example, adipic acid 3,4-epoxy-6-methylcyclohexylmethyl ester, 3,4-epoxy-6-methylcyclohexanecarboxylate.

(iii) Other compounds vinylcyclohexene oxide, l-methyl-4-isopropenylcyclohexene oxide.

Examples of the bisepoxy prepolymer include bisepoxy prepolymers derived from polyester glycol or polyether glycol and shrimp herohydrin, and epoxy resins of the formula.

These bisepoxides can be used alone or in combination of two or more. What should be noted here is that the liquid as a whole should be suitable for painting; for example, even if it is extremely viscous or solid, it can be dissolved in a low-viscosity liquid bis-epoxide. , can be used for the purpose of the present invention.

In the present invention, the above bisepoxy monomer or bisepoxy prepolymer can also be used in combination with a monoepoxy compound conventionally used as a diluent for epoxy resins. By using this monoepoxy compound in combination, the viscosity of the epoxy composition used for coating can be reduced to a level suitable for coating, and the stress remaining in the cured coating can be effectively alleviated. Of course, the monoepoxy compound used will also participate in the polymerization reaction by ring opening and will be effectively incorporated into the polymer chain.

As the monoepoxy compound, for example, alicyclic epoxy compounds such as butyl glycidyl ether, allyl glycidyl ether, styrene oxide, cyclopentene oxide, cyclohexene oxide, bicyclo(3°4)nonene-1,2, oxide, etc. can be used. can.

Suitable bis-epoxide coatings generally have a viscosity of 600 cps to 80 cps, particularly 160 cps to 400 cps, as measured on a Type B viscometer at 25°C.

As the photoinitiator, preferably used is a substance that initiates the cationic ring-opening polymerization of the bisepoxide described above under irradiation with ultraviolet light. Such a photoinitiator is known per se, and for example, a double salt of a Lewis acid and a photosensitive diazonium (Japanese Patent Publication No. 17040/1982) is used. Such a double salt liberates the Lewis acid catalyst by photolysis of the diazonium salt and initiates ring-opening polymerization of the bisepoxide. Other examples of photoinitiators include photosensitive aromatic onium salts (e.g., JP-A-50-151996, JP-A-50-151997, JP-A-50-158698, JP-A-51-5688).
No. 5, see Japanese Unexamined Patent Publication No. 53-124590).

These photoinitiators are generally used in catalytic amounts, in particular from 0.1 to 10% by weight, in particular from 0.3 to 3% by weight, based on bisepoxide.
is added to the bisepoxide in an amount of In order to blend the photoinitiator with the bisepoxide, the photoinitiator may be blended as is, or it may be blended after being dissolved in a solvent.

Of course, one or more of dyes, pigments, extender pigments, leveling agents, lubricants, viscosity modifiers, rust preventive pigments, and rust preventive agents can be blended into this coating composition.

This coating resin composition does not substantially contain a diluent.
This means that the content of diluents such as solvents per bis-epoxide does not exceed 10% by weight, and addition of a minute amount of solvent for the purpose of adding the photoinitiator is permitted.

Coating can be carried out by any means such as dip coating, roller coating, spray coating, or brush coating, but roller coating is preferred for the purpose of applying the coating thinly to the thickness described above.

(Effects of the Invention) According to the present invention, the generation of soot during laser welding is prevented by removing paint etc. from the edge of the metal plate in advance, and the negative effects caused by the generation of soot are eliminated. In addition, by applying a correction paint to the welded parts, rust and corrosion can be prevented, and especially when a photoinitiator-containing liquid polymerizable composition is used as a correction paint, the joints can be completely covered and have good adhesion. It has excellent performance and can be manufactured on a relatively short line.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the entire exterior can for a dry battery according to the present invention, and FIG. 2 is an enlarged sectional view of a welded portion of the exterior can for a dry battery according to the present invention. 3...Metal plate, 4...-ink, etc., 5...-joint, 6
...Correction paint.

Claims (1)

[Claims] (1) In an exterior can for dry batteries, which is made by butting together the edges of both sides of metal plates that have been coated with paint or the like on at least one of the surfaces or inner surfaces, and laser welding the butt points, the edges of both sides at the butt points. Before welding, the paint applied to the weld area is removed from each edge in a width of 0.5 to 3 mm, and the outer surface of the weld area is removed over a width of 1.0 to 8 mm larger than the width of the seam. An exterior can for a dry battery, characterized in that a correction paint is applied to a film thickness of 5 to 30 μm.