JPH10134782A - Synthetic resin jar and cover for sealed strorage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a jar and a cover excellent in balance in the moldability, mechanical strength and heat resistance thereof, as well as excellent in the barrier performance against water vapor thereof, ensuring the long service life of a sealed storage battery. SOLUTION: A resin compound composed of 50-90 parts by weight of polyphenylene ether and 5-50 parts by weight of high density polyethylene is molded into a mold to be used as a jar and a cover, where the configuration in which the polyphenylene ether resin component forms at least a matrix and the configuration in which the high density polyethylene component forms at least a matrix are scattered. The water vapor transmission coefficient at the 90% moisture condition according to the JISK 7129 B method is 0.7gmm/m24 h or less at the temp. of 25 deg.C. Accordingly, it is possible to provide the jar and cover with the same moldability and mechanical strength as those of conventional ABS resin made jar and cover, as well as excellent heat resistance and water vapor barrier characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery case and lid (hereinafter referred to as a battery case) for a sealed storage battery having an excellent balance between mechanical strength and heat resistance and having excellent steam barrier properties.

[0002]

2. Description of the Related Art Rechargeable batteries are widely used as power sources for vehicles such as automobiles, large vehicles, special vehicles, various electric products, and industrial equipment. In addition, demand for various batteries such as a lead storage battery, a nickel-cadmium battery, and a lithium battery is increasing. Along with this, there is a demand for larger storage battery cases, diversified designs, lighter weight, thinner, etc.
Demands for materials used for the molding, strength, heat resistance and the like are becoming strict.

Conventionally, for example, ABS (acrylonitrile butadiene-styrene copolymer) has been used as a resin for a battery case of a storage battery. ABS has excellent moldability,
It is a resin with excellent balance of rigidity, strength, and dimensional accuracy. For this reason, it has many achievements as a resin for storage battery case. However, ABS sometimes lacks heat resistance and strength. In such a case, modified polyphenylene ether is used. This modified polyphenylene ether is a mixture of polyphenylene ether and polystyrene, and the desired heat resistance can be obtained by arbitrarily changing the ratio thereof. Also suitable when flammability is required.

[0004] However, both resins have a disadvantage that they are inferior in water vapor barrier properties (permeate water vapor).

[0005] This is a phenomenon in which water in an electrolyte contained in a storage battery evaporates as water vapor during long-term use, passes through a storage battery case, and is dissipated to the outside.

[0006] As the use environment of the storage battery becomes high temperature and low humidity, and the expected life is prolonged, the tendency to decrease the electrolyte of the storage battery is increasing. When the amount of the electrolyte decreases, the internal resistance of the storage battery increases, which seriously impairs the discharge performance. Therefore, such a phenomenon is not preferable, and it is desired to use a resin that transmits as little water vapor as possible.

On the other hand, from this viewpoint, use of polypropylene may be considered. Polypropylene is a resin having excellent steam barrier properties and excellent moldability. However, from the viewpoint of mechanical strength and heat resistance, it is not always sufficient, and studies have been made on blending inorganic fillers such as talc, but when talc is blended, there has been a problem that impact resistance is reduced. . JP-A-60-3420 describes a composition in which talc and ethylene propylene rubber are blended to improve the balance. However, molded articles using these compositions are also not always sufficient in mechanical strength and balance of dimensional characteristics, and when flame retardancy is required, it is difficult to impart flame retardancy. However, there is a disadvantage that a large amount of a flame retardant must be added.

[0008] Under such circumstances, the current situation is that none of the materials for the storage battery case is necessarily satisfactory.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a battery case having an excellent balance of moldability, mechanical strength, and heat resistance and an excellent steam barrier property. It was made for the purpose.

[0010]

According to the present invention, there is provided a resin composition comprising (a) 50 to 95 parts by weight of a polyphenylene ether-based resin and (b) 5 to 50 parts by weight of a high-density polyethylene. A) a form in which the component forms at least a matrix (continuous phase), and a form in which the component (b) forms at least the matrix are dispersed bodies, and the humidity is 90% based on the method B of JISK7129.
Has a water vapor transmission coefficient of 0.7 g · mm /
An object of the present invention is to solve the above-mentioned problem by using a synthetic resin battery container or a lid for a sealed storage battery characterized by having a capacity of m ² · 24 h or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

Polyphenylene ether resin (a) The polyphenylene ether resin used in the present invention is polyphenylene ether or a mixture of polyphenylene ether and styrene resin.

Here, the polyphenylene ether used in the present invention is:

(Equation 1) Is a homopolymer or a copolymer having a structure represented by the general formula:

[0014]

Wherein Q ¹ represents a halogen atom, a primary or secondary alkyl group, an aryl group, an aminoalkyl group, a hydrocarbonoxy group or a halohydrocarbonoxy group, and Q ² represents Atom, a halogen atom, a primary or secondary alkyl group, an aryl group, a haloalkyl group, a hydrocarbonoxy group or a halohydrocarbonoxy group, and m represents a number of 10 or more. It is a polymer or a copolymer. Preferred examples of the primary alkyl group for Q ¹ and Q ² include methyl, ethyl, n-propyl, n-
Butyl, n-amyl, isoamyl, 2-methylbutyl,
n-hexyl, 2,3-dimethylbutyl, 2-, 3- or 4-methylpentyl or heptyl. Suitable examples of secondary alkyl groups are isopropyl, sec-butyl or 1-ethylpropyl. In many cases, Q ¹ is an alkyl group or a phenyl group, particularly an alkyl group having 1 to 4 carbon atoms, and Q ² is a hydrogen atom. Suitable polyphenylene ether homopolymers include:
For example, it is composed of 2,6-dimethyl-1,4-phenylene ether units. Suitable copolymers include:
A random copolymer comprising a combination of the above units and 2,3,6-trimethyl-1,4-phenylene ether units. Many suitable homopolymers or random copolymers are described in patents and literature. For example, molecular weight,
Also suitable are polyphenylene ethers containing molecular moieties that improve properties such as melt viscosity and / or impact strength.

The polyphenylene ether used here preferably has an intrinsic viscosity at 30 ° C. of 0.2 to 0.8 dl / g measured in chloroform. More preferably, the intrinsic viscosity is 0.2 to 0.7 dl / g, and particularly preferably, it is 0.25 to 0.6 dl / g. If the intrinsic viscosity is less than 0.2 dl / g, the impact resistance of the composition will be insufficient, and if it exceeds 0.8 dl / g, the moldability will be unsatisfactory.

The styrene resin used in the present invention is polystyrene or rubber-reinforced polystyrene. These blending amounts are 10 to 90 when the total of polyphenylene ether and these styrene resins is 100% by weight.
% By weight is preferred.

If it is less than 10% by weight, the moldability is unsatisfactory, and if it exceeds 90% by weight, the heat resistance is too low, which is not preferred.

The high-density polyethylene used in the present invention is a homopolymer of ethylene or a copolymer containing ethylene as a main component with an α-olefin. The above α
The olefin is, for example, propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1 and the like, and C3-C8 is preferred from the viewpoint of easy availability.

The high-density polyethylene used in the present invention is:
The density according to JIS K-6760 is 0.940 to 0.9
It is preferably 80 g / cm ³ , more preferably 0.945 to 0.970 g / cm ³ , and particularly preferably 0.950 to 0.965 g / cm ³ . If the density is less than 0.940 g / cm ³ , heat resistance and rigidity are insufficient, and if it exceeds 0.980, it is difficult to manufacture.

The high-density polyethylene has a melt flow rate (MFR; 190 ° C., load 2.16 kg) of 0.1.
The range is preferably from 0.05 to 100 g / 10 minutes, more preferably from 0.1 to 80 g / 10 minutes, and particularly preferably from 0.5 to 50 g / 10 minutes. If the value of MFR is lower than this range, there is a problem in moldability, and if it is higher than this range, the level of mechanical strength is not preferable.

In the present invention, a block copolymer comprising a vinyl aromatic compound polymer block A and a conjugated diene compound polymer B and / or a hydrogenated product thereof are added to improve the impact strength. Is preferred. The block copolymer referred to herein is a vinyl aromatic compound-conjugated diene block copolymer having a structure having at least one each of a chain block A derived from a vinyl aromatic compound and a block B derived from a conjugated diene,
The arrangement of the blocks A and B includes those having a linear structure, a branch structure, or a taper structure. Further, a part of these structures may include a random chain derived from a random copolymer part of a vinyl aromatic compound and a conjugated diene. Among them, those having a linear structure are preferable, and those having a triblock structure are more preferable.

The hydrogenated product of the block copolymer is a block copolymer in which the aliphatic unsaturated groups of block B have been reduced by hydrogenation, and the proportion of the unsaturated bonds remaining without hydrogenation. Is preferably 20% or less,
% Or less is more preferable, but is not limited. Also,
You may use together with the block copolymer which is not hydrogenated.

The vinyl aromatic compound is preferably styrene, α-methylstyrene, paramethylstyrene, vinyltoluene, vinylxylene, more preferably styrene.

The conjugated diene is preferably 1, 3
-Butadiene, isoprene, 2-methyl-1,3 butadiene.

Specific examples of the block copolymer include a styrene-butadiene-styrene block copolymer and a styrene-isoprene-styrene block copolymer, and a plurality of these may be used.

The proportion of the repeating unit derived from the vinyl aromatic compound in the vinyl aromatic compound-conjugated diene block copolymer is preferably in the range of 10 to 70% by weight, and more preferably in the range of 15 to 50% by weight. More preferred.

The block copolymer and its hydrogenated product preferably have a toluene solution viscosity at 25 ° C. in the range of 30,000 to 10 cps, more preferably 10,000 to 30 cps, as a measure of their molecular weight. is there. In the range of more than 30,000 cps, there is a problem in molding processability of the final composition, and 10 c
In the range of values smaller than ps, the mechanical strength level is low, which is not preferable.

Further, other components that can be added to the composition of the present invention as necessary include, for example, antioxidants, weathering improvers, nucleating agents, impact modifiers, plasticizers, which are well-known to thermoplastic resins. Fluidity improvers and the like can be used. Also, organic fillers,
Addition of a reinforcing agent, an inorganic filler, for example, glass fiber, talc, mica, calcium carbonate, silica, clay, etc. is effective in improving rigidity, heat-resistant dimensional characteristics and the like. For practical use, well-known colorants and their dispersants can be used. In the present invention, it is practically preferable to add a flame retardant in order to impart flame retardancy. As the flame retardant used in the present invention, various known flame retardants can be used, and there is no particular limitation, and the amount of the flame retardant is an amount required to obtain a target flame retardant level. Preferably, a phosphorus-based, halogen-based, inorganic-based flame retardant, a flame retardant auxiliary, or a combination thereof is used.
1 to 50 parts by weight is blended with respect to 00 parts by weight.

[Structure of Resin Molded Body] The present invention comprises a composition containing a polyphenylene ether-based resin (a) and a crystalline resin (b), and the component (a) forms at least a matrix (continuous phase). It is characterized in that the form and the form in which the component (b) forms at least a matrix (continuous phase) are dispersed.

For example, component (a) forms a matrix (continuous phase), component (b) forms a domain (A), and component (b) forms a matrix (continuous phase). Wherein component (a) forms a domain (B),
The form (C) in which the components (a) and (b) take a continuous phase with each other is considered. The form in which the component (a) forms at least a matrix (continuous phase) and the form in which the component (b) is at least The form in which the matrix (continuous phase) is formed is present in a dispersed state when the form (A) appears at various places of the composition and the molded product, the form (B) appears, Or the appearance of form (C).

For example, in the vicinity of the surface layer of the molded product, the shape (A)
On the inside, there is a form in which the form (B) appears, and conversely, in the vicinity of the surface layer, the form (B) is formed, and inside the form, the form (A) is formed. Of course, the forms (A), (B) and (C) may appear twice or more in the thickness direction of the molded body. Also, a form of only (C) is also conceivable.

Here, this embodiment (A), (B), (C)
Can be confirmed by dyeing the composition or molded article with ruthenium tetroxide, forming an ultrathin section, and observing the section using a transmission electron microscope.

[Composition Ratio of Constituent Components] The composition ratio of the components (a) and (b) described above is as follows, with the total amount of (a) + (b) being 100% by volume.

Component (a): 50 to 95% by weight, preferably 60 to 95% by weight, particularly preferably 70 to 95% by weight.

Component (b): 5 to 50% by weight, preferably 5 to 40% by weight, particularly preferably 5 to 30% by weight.

When component (a) is less than 50% by weight, heat resistance, rigidity and flame retardancy are unsatisfactory.
If it is less than the weight percentage, the water vapor permeability is unsatisfactory.

[Melting Shear Viscosity Ratio of Each Component and Dependence of Melting Shear Viscosity Ratio on Shear Rate] The form in the composition of the present invention is the same as the form in which the polyphenylene ether-based resin (a) forms at least a matrix (continuous phase). And a form in which the high-density polyethylene (b) forms at least a matrix (continuous phase).

The conditions that can take the form of the present invention are as follows: at a certain composition ratio, the melt shear viscosity ratio (A) of component (a) and component (b) at 280 ° C. and γ30 is the viscosity ratio at which the sea-sea structure is formed. When the value is larger than the value (W1), the melt shear viscosity ratio (B) of the component (a) and the component (b) at 300 ° C. and γ300 becomes smaller than the viscosity ratio (W2) taking the sea-sea structure, or
When (A) is smaller than (W1), (B) is larger than (W2).

The preferred conditions for taking the form of the present invention are that the volume ratio of component (a) to component (b) is 15 / 85-9.
When it is within the range of 5/5 and (A) is larger than (W1) and smaller than 100, (B) is smaller than (W2) or (A) is smaller than (W1) and 0.1. If it is larger, (B) will be larger than (W2).

More preferably, the volume ratio of component (a) to component (b) is in the range of 25/75 to 95/5, and (A) is greater than (W1) and less than 50. When (B) is less than (W2), or when (A) is less than (W1) and greater than 0.2, (B) is greater than (W2).

More preferably, the volume ratio of component (a) to component (b) is 35/65 to 90/10.
And (A) is larger than (W1) by 20
If smaller, (B) will be smaller than (W2) or
Alternatively, when (A) is smaller than (W1) and larger than 0.6, (B) is larger than (W2).

The term "melt shear viscosity" used herein means JIS K
The method described as a reference test of No. 7210, that is, a shear viscosity (shear viscosity) when a molten resin is extruded from a capillary at a constant speed. As a specific device, a Koka type flow tester (instrument) is used. Ron Capillary Rheometer). Using this device, for example, at various temperatures, the nozzle diameter is 1 mm and the nozzle length is 1
The measurement can be performed by setting the distance to 0 mm and changing the extrusion speed.

[Production and Molding Method of Composition] As a method for obtaining the thermoplastic resin composition of the present invention, various kneaders, for example, a single-shaft and multi-shaft kneader, a Banbury mixer, a roll, a Brabender plastogram In the like, after kneading the above components, a method and a suitable solvent for cooling and solidifying, for example, hexane, heptane, benzene, toluene, the above components are added to hydrocarbons such as xylene and derivatives thereof,
A solution mixing method or the like in which soluble components are mixed together or a soluble component and an insoluble component are mixed in a suspended state is used. From the industrial cost, the melt-kneading method is preferred, but not limited.

The method of molding the composition of the present invention is not particularly limited, and molding methods generally used for thermoplastic resin compositions, for example, injection molding, hollow molding, extrusion molding, sheet molding, thermoforming , Rotational molding, lamination molding and the like can be applied.

[Water Vapor Permeability of Molded Article] The water vapor permeability coefficient of the molded article of the present invention at 25 ° C. is JIS K712.
The value at a humidity of 90% measured according to the method B of Example 9 is 0.
7 g · mm / m ² · 24 h or less, preferably 0.
6 g · mm / m ² · 24h or less, particularly preferably 0.5 g · mm / m ² · 24h or less.

If this value exceeds 0.7 g · mm / m ² · 24 h, the period leading to dry-up described later is short, which is not preferable.

[0047]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these ranges.

The following components were used as each component.

1. Polyphenylene ether: Poly-2,6-
Dimethyl-1,4-phenylene ether (Mitsubishi Gas Chemical Company)
The intrinsic viscosity measured at 30 ° C in chloroform is 0.
1. 40 dl / g) (hereinafter abbreviated as PPE) 2. Polystyrene: HT478 (rubber reinforced polystyrene) manufactured by Mitsubishi Chemical Corporation (hereinafter abbreviated as PS) High-density polyethylene: Mitsubishi Polyethylene manufactured by Mitsubishi Chemical Corporation
-HD HY340 MFR: 1.4 (hereinafter abbreviated as PE-1) Shorex Super 4551H M manufactured by Showa Denko KK
FR: 0.02) (hereinafter abbreviated as PE-2). 4. Hydrogenated vinyl aromatic compound-conjugated diene block copolymer: Clayton G1652 (Styrene butadiene-styrene copolymer hydrogenated styrene content 30% by weight) manufactured by Shell Co. (hereinafter abbreviated as SEBS) Flame retardant: Saytex8010 manufactured by Albemarle
(Hereinafter abbreviated as S8010) Antimony trioxide (hereinafter Sb ₂ O ₃ ) manufactured by Sumitomo Metal Mining Co., Ltd.
5. Triphenyl phosphate (hereinafter abbreviated as TPP) manufactured by Daihachi Chemical Co., Ltd. Polypropylene: Mitsubishi Polypropylene BC manufactured by Mitsubishi Chemical Corporation
6. 03C (hereinafter abbreviated as PP) ABS: TAFLEX TFX-21 manufactured by Mitsubishi Chemical Corporation
0 (hereinafter abbreviated as ABS) [General physical property evaluation method] Using a twin-screw extruder (manufactured by Nippon Steel Works Ltd.), the resin component is melt-kneaded at a cylinder temperature of 210 ° C. and a screw rotation speed of 250 rpm to obtain a resin composition. Obtained.

Next, the resin composition was subjected to an injection molding machine (manufactured by Nippon Steel Works, mold clamping force: 55 T) at a cylinder temperature of 24.
Injection molding was performed under the conditions of 0 ° C. and a mold temperature of 60 ° C. to form a molded product, which was evaluated by the following method.

Table 1 shows the results.

(1) Izod Impact Test A notched Izod impact test was performed in accordance with ASTM D256.

(2) Flexural Modulus A three-point bending test was performed according to a bending test method according to ASTM D790.

(3) Heat Deformation Temperature A load deflection test was performed under the conditions of 18.6 kg / cm ^{2 in} accordance with ASTM D648.

(4) Combustion test According to UL94, a test was performed using a test piece having a thickness of 1/16 inch.

[Water Vapor Permeability] The above resin composition was prepared using an injection molding machine (manufactured by Nippon Steel Works, mold clamping 150T) under the conditions of a cylinder temperature of 240 ° C. and a mold temperature of 60 ° C. at 150 mm ×
A sheet having a thickness of 150 mm and a thickness of 1 mm was formed and evaluated at 25 ° C. at a humidity of 90% based on the method B of JIS K7129. Table 1 shows the results.

[0057]

[Table 1] [Morphological observation] A test piece obtained by injection molding was cut out, subjected to a face-out operation perpendicular to the injection molding direction, stained with ruthenium tetroxide and osmium tetroxide, and 0.1 μm thick using a microtome with an ultra-thin section. Make an ultra-thin section of the sample. Using a transmission electron microscope (TEM: JEM10 manufactured by JEOL Ltd.)
0CX).

One example is shown in FIGS. 1 and 2
A molded article of the composition of Example 1 was subjected to the above pretreatment, and then to a magnification of 1
FIG. 1 is a photograph observed 0.2 mm inside the surface layer, and FIG. 2 is a photograph observed 1.0 mm inside the surface layer. In the figure,
The part that looks white is PPE / PS, the part that looks black is PE, and the part that looks like salami is HIPS-derived butadiene rubber.

In FIG. 1, PO is a matrix, and FIG.
In this example, PPE / PS is a matrix, which indicates that the component (a) matrix and the component (b) matrix are mixed.

[Evaluation as a Storage Battery] A sealed lead-acid storage battery having a capacity of 7 hours was prototyped and tested and evaluated.

The battery case materials used for the trial production were an ABS resin (Comparative Example-4), a polypropylene resin (Comparative Example-5), a conventional polyphenylene ether resin (Comparative Example-1), and a resin according to the present invention (Example-1). ). The prototype storage battery was subjected to a life test in an environment with a humidity of 30% and a temperature of 60 ° C. The capacity test during the life test was performed at an hourly rate. Table 2 shows the results.

[0062]

[Table 2] In the storage battery using the ABS battery case, the electrolytic solution permeated from the battery case and the internal resistance increased, that is, the battery life was shortened by dry-up. The electrode plate was still in a state where the discharge function could be maintained. Due to the high temperature, the storage battery using polypropylene resin did not surpass the internal pressure of the storage battery, the battery case expanded, the internal resistance increased, and the capacity rapidly decreased. Batteries using conventional polyphenylene ether resin have the same bending strength as ABS resin,
And since the water vapor permeability coefficient is about 60%,
The time to dry-up increased, but was still at an inadequate level. On the other hand, the storage battery using the resin according to the present invention has the same bending strength as that of the ABS resin, and the water vapor transmission coefficient can be reduced to about 30%. The maximum life performance.

As described above, since water cannot be supplemented during the use period in the sealed storage battery, if the life is extended by dry-up, the life performance may not be the original life of the storage battery plate. all right. It has been found that suppressing the permeation of the electrolyte by the material of the battery case is effective in increasing the life performance of the storage battery.

[0064]

According to the present invention, it is possible to extend the life of the sealed storage battery by suppressing the dry-up by applying a battery case resin suitable for the sealed storage battery. Because small storage batteries have a large surface area, they tend to dry up easily,
Long life is a necessary condition for a small storage battery to be used everywhere in the market, and the present invention has made it possible to provide an inexpensive and long life sealed lead storage battery. Its industrial value is extremely large.

[Brief description of the drawings]

FIG. 1 is a photograph taken at a magnification of 10,000 times using a transmission electron microscope at an inside of 0.2 mm from the surface layer of a molded article of the composition of Example 1.

FIG. 2 is a photograph taken at a magnification of 10,000 times using a transmission electron microscope at an inner side of 1.0 mm from the surface layer of a molded article of the composition of Example 1.

[Explanation of symbols]

 None

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Koji Nishida, Inventor Mitsubishi Engineering Plastics Co., Ltd. 1-1-1, Kyobashi, Chuo-ku, Tokyo (72) Inventor Masashi Iwata Shono Nishino, Kichijoin, Minami-ku, Kyoto-shi No. 1, Nobaba-cho, Japan Battery Co., Ltd. (72) Inventor Isamu Kurisawa, No. 1, Nishino-sho, Inosinaba-cho, Minami-ku, Kyoto-shi, Japan

Claims (1)

[Claims] 1. (a) Polyphenylene ether resin 5
A resin composition comprising 0 to 95 parts by weight and (b) 5 to 50 parts by weight of a high-density polyethylene, wherein the component (a) forms at least a matrix (continuous phase);
(B) A molded product in which the component forms at least a matrix in a dispersed state, and has a water vapor transmission coefficient at 90% humidity of 0.7 g · mm / m ^{2 at} 25 ° C.
-A synthetic resin battery case or lid for a sealed storage battery characterized by being 24 hours or less.