JPH02236950A - Cell - Google Patents

Abstract

PURPOSE:To improve crack resistance by filling the dent portion between positive and negative electrodes exposed to the same plane with ultraviolet curing resin whose photopolymerizing prepolymer and photopolymerizing monomer are specified respectively. CONSTITUTION:An insulating member 1 consisting of ultraviolet curing resin is cured after a dent portion B formed of a terminal assembly 2 which doubles as a positive electrode terminal, a metal case 3 which contains a generating element A and doubles as the terminal of a negative electrode and an insulating packing 4 is filled with the insulating member 1. Photopolymerizing prepolymer used for ultraviolet curing resin 1 consists of urethane acrylate resin and photopolymerizing monomer used therefore consists of acryl resin. Thus, it is possible to reduce an internal strain after curing and also improve crack resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a battery constructed by filling an exposed terminal surface of the battery with an ultraviolet curing resin.

Conventional technology Conventionally, an insulating material is interposed between the positive and negative terminals of a battery that are exposed on the same surface to prevent short circuits caused by contact with external metal parts or liquid leaks caused by condensation. Efforts were made to prevent the phenomenon. Especially in the case of high-output batteries such as lithium batteries or alkaline batteries, when a short circuit occurs, a large current will flow, the battery itself will generate heat, the battery seal may become deformed, and the built-in electrolyte may damage the device in which it is used. When water or other liquid is present between the two electrode terminals and a liquid junction occurs, electrolysis of water occurs in batteries with a potential of 3V, such as lithium batteries, which corrodes the metal terminals. There were other problems. Insulating materials that solve these problems are those that have better adhesion to metals than conventional ones. Polymeric materials have been used that provide adhesive properties. These adhesives are mainly solvent-soluble or two-component adhesive compositions, but they require a long time to harden.
Solvent-soluble types require a step to scatter the solvent in the production line, which increases battery manufacturing costs. On the other hand, UV-curable adhesive compositions are solvent-free and consist of a photopolymerizable prepolymer with a reactive group such as a double bond in the molecule, a photopolymerizable monomer as a diluent, and a photoreaction initiator as the main components. It is a mold adhesive composition that instantly cures the adhesive by irradiating it with ultraviolet light, so it is becoming widely used.

Problems to be Solved by the Invention As described above, the adhesive curing reaction of an ultraviolet curable resin is caused by a polymerization reaction between a photopolymerizable prepolymer and a photopolymerizable monomer when irradiated with ultraviolet rays, resulting in adhesive curing. For this reason, if the resin is thick, specifically o. When the wall thickness is 3"g or more, the photopolymerization reaction starts from the surface layer of the resin, so the curing rate of the resin is different between the surface layer and the inner layer. Since the degree of polymerization is different, the hardening rate of the resin after curing is Adhesive curing reaction takes place in a state where strain is contained inside the resin.In this way, when the resin adheres and hardens on the exposed surface of the terminal as an insulating member with the strain remaining inside the resin, it will cause damage during battery storage and use. Cracks often occur on the resin surface due to long-term environmental stress caused by the natural environment or significant environmental stress such as short-term thermal shock, rendering it useless as an insulating member. .

Means for Solving the Problems The present invention has solved the above-mentioned problems by conducting intensive studies on 4@materials and using 20 to 40 parts by weight of urethane acrylate resin as a photopolymerizable prepolymer. By using an ultraviolet curable resin containing 60 to 80 parts by weight of acrinole resin as a photopolymerizable monomer, the internal strain after curing is small, and an insulating member with excellent crack resistance is interposed in the exposed terminal part K of the battery. be.

Effect: Compared to other general-purpose UV-curable resins, the UV-curable resin with the above-mentioned formulation forms a polyurethane structure and produces a relatively viscous and elastic cured product. It is thought that this has the effect of absorbing the residual strain generated inside the cured product.

Embodiment FIG. 1 is a sectional view of a main part of a battery showing an embodiment of the present invention.

1 in the figure is an insulating member made of ultraviolet curable resin,
This consists of a terminal board 2 that also serves as the positive terminal, a metal container 3 that houses the power generating element and also serves as the negative terminal, and insulation between both terminals inside the battery, as well as to prevent the built-in power generating element from leaking outside. The concave portion B formed by the insulating packing 4 to prevent this is filled and hardened. Reference numeral 5 denotes a lead wire derived from the active material of Japanese birch of the power generation element, and is electrically connected to the inner surface of the positive electrode terminal 2. The ultraviolet curable resin includes 20 to 40 parts by weight of urethane acrylate resin as a prepolymer and 60 to SOFI parts of acrylic resin as a monomer. Penzophenone is commonly used as a photopolymerization initiator. A carbonyl compound such as penzoin isoptynolether is comprised in an amount of 0.6 to 1.0 parts by weight. Note that this is a prepolymer of UV-curable resin. The blending amount of the monomer material as a diluent as described above is the optimum blend to obtain the viscosity necessary to pour the resin uniformly into the recess B of the battery with good workability, and it is also It is also a general-purpose blending ratio for ultraviolet curable resins. In addition, as the acrylic) V resin as the diluent monomer,
Min-I amount is about 100-300 viscosity is 1-eocpS
Specific substances include 2-ethylhexyl acrylate, 2-hydroxyglovir acrylate, 1,6-hexane diacrylate, and 1,3-butanediol diacrylate. Next, the urethane acrylate resin is an unterminated -HOO obtained by reacting an acrylate with an -OH group with a diisocyanate.
It is obtained by reacting a polyester polyol with an acrylate having a group, and has a molecular weight of 1000 to 80.
It is a resin of about 0.00. Next, regarding the effects of the present invention, Table 1 shows the results of a comparative experiment with ultraviolet curable resins using other prepolymer resins. In addition, monomer resin was used in the experiment. All polymerization initiators were mixed under the same conditions, that is, 20 to 40 parts by weight of the prepolymer. The monomer resin was in the range of 60 to 80 parts by weight, and the photopolymerization initiator Q was in the range of 5 to 1.0 parts by weight. Ultraviolet light is 160% using a high-pressure mercury lamp as a light source.
0 [I! IJ/cI] for 30 seconds to cure the resin. The numbers shown in Table 1 are the heat applied to the terminal recess B of a cylindrical lithium battery with ultraviolet curable resin and the cured resin heated to -40'C and 86°C alternately for 2 hours. The impact tester was subjected to 1o cycles at 1 cycle/L'4 hours. These are the results of an investigation and comparison of 100 samples each regarding cracking of the resin when thermal shock was applied for 30 cycles and 100 cycles.

(Left below) Effects of the invention As is clear from the experimental results in Table 1, 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. This provides a battery with excellent long-term reliability.

[Brief explanation 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... Ultraviolet curing resin, 2.3...
Positive/negative terminals, 4... Insulation packing, ▲...
...Power generation element, B...Indentation. Name of agent: Patent attorney Shigetaka Awano and one other person
1 卜玖石sarakakug, Yoryu 2-LPI! % ÷ A - 11 strokes

Claims (2)

[Claims] (1) A battery in which a recess 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, and the photopolymerizable prepolymer of the ultraviolet curable resin is A battery characterized in that a urethane acrylate resin and a photopolymerizable monomer are made of an acrylic resin. (2) The amount of UV curable resin is 20 to 40 parts by weight of photopolymerizable prepolymer and 60 to 60 parts by weight of photopolymerizable monomer.
80 parts by weight of the battery according to claim 1.