JPH0793131B2 - Battery - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery configured by filling a terminal exposed surface of the battery with an ultraviolet curable resin.

2. Description of the Related Art Conventionally, a positive electrode terminal of a battery and a negative electrode terminal exposed on the same surface between the terminals have an insulating member interposed between them to cause a short circuit due to contact with a metal piece from the outside or a liquid junction due to dew condensation. It was intended to prevent the phenomenon. Especially in the case of high output batteries such as lithium batteries and alkaline batteries, when a short circuit occurs, a large current flows, the battery itself generates heat, the battery sealing part is deformed, and the built-in electrolyte leaks out and damages the equipment used. Or, when water or the like exists between both terminals and becomes a liquid junction, electrolysis of water occurs in a battery showing a potential of 3V class such as a lithium battery, and the terminal metal is corroded. There was a problem. As an insulating member that solves these problems, a polymer material having excellent adhesion and adhesion to a metal has been used conventionally. These adhesives are mainly solvent-soluble type or two-liquid mixed type adhesive compositions, but it takes a long time to cure, and solvent-soluble type adhesives have a production line. In this case, a step of scattering the solvent is required, which increases the battery manufacturing cost. On the other hand, a UV-curable adhesive composition is a solvent-free composition containing a photopolymerizable prepolymer having a reactive group such as a double bond in the molecule, a photopolymerizable monomer as a diluent, and a photoreaction initiator as main components. It is a mold-bonding composition and is being widely used because it is instantly cured by irradiation with ultraviolet rays.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the adhesive curing reaction of an ultraviolet curable resin, a polymerization reaction of a photopolymerizable prepolymer and a photopolymerizable monomer occurs by being irradiated with ultraviolet rays as described above, and the adhesive is cured. For this reason, when the resin has a large thickness, specifically, when it has a thickness of 0.3 m / m or more, the photopolymerization reaction is started from the surface layer of the resin, so that the resin in the surface layer and the inner layer of the resin Since the curing speed and the degree of polymerization of the resin are different, the adhesive curing reaction is carried out in the state where the strain is contained in the cured resin. When the resin adheres and cures to the exposed surface of the terminal as an insulating member while the strain remains inside the resin, long-term environmental stress caused by the natural environment during storage or use of the battery, or short-term environmental stress In many cases, the surface of the resin was cracked by human environmental stress such as thermal shock, so that the resin could not be used as an insulating member.

Means for Solving the Problems The present invention has been made by solving the above-mentioned problems by intensively studying a resin material, wherein a urethane acrylate resin as a photopolymerizable prepolymer is 20 to 40 parts by weight, and as a photopolymerizable monomer. By using an ultraviolet curable resin composed of 50 to 80 parts by weight of an acrylic resin, an insulating member having a small internal strain after curing and excellent in crack resistance is interposed in a terminal exposed portion of a battery.

The UV-curable resin with the above composition has a polyurethane structure as compared with other general-purpose UV-curable resins, and produces a relatively viscous and elastic cured product. Therefore, it is considered to have an action of absorbing the residual strain generated inside the cured product.

Example FIG. 1 is a cross-sectional view of a main part of a battery showing an example of the present invention.

In the figure, 1 is an insulating member made of an ultraviolet curable resin,
This is because the terminal plate 2 also serving as the positive electrode terminal, the metal container 3 having the power generating element A built therein and also serving as the negative electrode terminal, both terminals are insulated inside the battery, and the built-in power generating element A leaks to the outside. It is filled and hardened in the recess B formed by the insulating packing 4 for preventing the above. Reference numeral 5 is a lead wire derived from the positive electrode active material of the power generation element, and is electrically connected to the inner surface of the positive electrode terminal 2. As UV curable resin, urethane acrylate resin as prepolymer is 20-40 parts by weight, acrylic resin as monomer is 50-
80 parts by weight, 0.5 to 1.0 part by weight of carbonyl compounds such as benzophenone and benzoin isobutyl ether that are commonly used as photopolymerization initiators. The prepolymer of the UV-curable resin and the monomer material as a diluent are blended in the amounts as described above in order to obtain the viscosity required for pouring the resin uniformly into the recess B of the battery with good workability. Is the most suitable compounding ratio, and is also a general-purpose compounding ratio for ordinary UV-curable resins. The acrylic resin as a monomer of the diluent has a molecular weight of about 100 to 300 and a viscosity of about 1 to 60 cps, and specific substances include 2-ethylhexyl acrylate, 2-hydroxypropyl acrylate, and 1.6-hexane. Examples thereof include diacrylate and 1.3-butanediol diacrylate.
Next, the urethane acrylate resin is obtained by reacting a polyester polyol with an acrylate having a terminal -NCO group obtained by reacting an acrylate having a -OH group with a diisocyanate in an equimolar manner, and has a molecular weight of 1,000.
It is about 8000 resin. Next, regarding the effect of the present invention,
Table 1 shows the results of a comparison experiment with an ultraviolet curable resin using another prepolymer resin. In addition, in the experiment, the monomer resin, the polymerization initiator, etc. all had the same compounding conditions,
That is, 20-40 parts by weight of prepolymer resin and 50 parts of monomer resin
-80 parts by weight and 0.5 to 1.0 part by weight of the photopolymerization initiator. Ultraviolet rays were irradiated for 30 seconds with a light amount of 1500 [mJ / cm ² ] using a high pressure mercury lamp as a light source to cure the resin. The numbers shown in Table-1 are thermal shocks in which UV curable resin is applied to the terminal recess B of a cylindrical lithium battery and the cured product is alternately exchanged for 2 hours under the temperature conditions of -40 ° C and 85 ° C. 1 for testing machine
A cycle of 4 hours, 10 cycles, 30 cycles, 100 cycles, 10 cycles each for resin cracking when thermal shock was applied
It is the result of the investigation and comparison of 0 samples.

Effects of the Invention As is clear from the experimental results in Table 1 above, the ultraviolet-curable resin containing the urethane acrylate resin of the present invention as a prepolymer is extremely effective against environmental stress such as thermal shock, It is intended to provide a battery with excellent reliability.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a battery using the ultraviolet curable resin of the present invention as an insulating member. 1 ... UV curable resin, 2, 3 ... Positive / negative electrode terminals, 4 ...
… Insulating packing, A… Power generation element, B… Dimple.

Claims (2)

[Claims] 1. A battery in which a recessed portion formed between a positive electrode terminal and a negative electrode terminal exposed on the same surface is filled with an ultraviolet curable resin as an insulating member, which is a photopolymerizable prepolymer of the ultraviolet curable resin. A battery in which the polymer is a urethane acrylate resin and the photopolymerizable monomer is an acrylic resin. 2. The ultraviolet curable resin is compounded in an amount of 20 to 40 parts by weight of a photopolymerizable prepolymer and 50 to 50 parts of a photopolymerizable monomer.
The battery according to claim 1, which is 80 parts by weight.