JP2782454B2 - Stabilized paste-like conductive composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a paste-like conductive composition, and more particularly to a heat-stabilized paste-like conductive composition.

(Prior art) In recent years, with the development of electronics, various electronic devices have been reduced in size and weight, and components, such as capacitors and batteries, constituting the devices have been small, thin and lightweight.
Further, a highly reliable one that does not leak liquid is desired.

On the other hand, in integrated circuits such as ICs and LSIs used in various electronic devices, failures due to static electricity have increased as the degree of integration has increased, and when these parts are transported or used. There is a strong demand for prevention of static electricity when using electronic devices.

Inorganic or organic conductive compositions have been developed to meet the above demand, but inorganic conductive compositions have high conductivity but have poor processability.

On the other hand, the organic polymer conductive composition is excellent in processability, and can be easily processed into any shape such as a paste-like or flexible thin film. It has great advantages in terms of size, thickness and weight reduction.

As such a polymer conductive composition, a polymer having a polar group in its molecular structure, such as polyethylene oxide (hereinafter referred to as PEO) or polypropylene oxide (hereinafter referred to as PPO), is dissolved in an organic solvent. A polymer obtained by forming a thin film by a casting method, immersing the thin film in a solution in which an alkali metal salt is dissolved in an organic solvent, and then drying.
Complexes of alkali metal salts are known [for example, Br.
olymer J., 7 , 319 (1975); Fast Ion Transfer in Ioni
cs 5 , 685 (1981)]. The composite has a relatively high ionic conductivity at room temperature.

However, a complex in which an alkali metal salt is dissolved in polyethylene oxide or polypropylene oxide alone can be in the form of a paste.However, polyethylene oxide alone has high solubility in water and can be mixed with plastic as an antistatic agent. , Which is extracted with water and the antistatic effect gradually decreases. In addition, polypropylene oxide alone has low solubility of alkali metal salts and low conductivity.

On the other hand, a complex in which polyethylene oxide and / or polypropylene oxide is polymerized with a urethane bond or the like and an alkali metal salt is dissolved can be made into a paste by adjusting the degree of cross-linking. May be unstable.

In these composites, anions such as halogen anions, halide anions, halides, and organic acid anions are used as alkali metal salts, but in order to obtain high conductivity, perchlorates such as lithium perchlorate are used. preferable. However, perchlorates are dangerous and mixtures with organic matter can even explode when heated. For this reason, the amount of perchlorate added is low, up to a few wt%. In addition, polyethylene oxide-based or polypropylene oxide-based polymers have poor thermal stability and are decomposed by heating, so there is a greater danger when a large amount of perchlorate is contained.

(Problems to be Solved by the Invention) An object of the present invention is to provide a paste-like conductive composition having a high ionic conductivity, and a conductive composition which is thermally stable and has no danger of explosion. Things can be provided.

(Means for Solving the Problems) As a result of intensive studies, the present inventors have completed a paste-like conductive composition that can achieve the above object.

That is, the content of alkali metal perchlorate is 8% by weight or more.
A stabilized paste, comprising a block copolymer of polyethylene glycol and polypropylene glycol containing not more than 10% by weight, wherein the content of ethylene oxide chains in the copolymer molecule is from 10 mol% to 50 mol%. Is a conductive composition in the form of a solid.

The paste-like conductive composition containing a large amount of the alkali metal perchlorate was thermally more stable than the block copolymer alone and the decomposition starting temperature was increased. Although the reason is not clear, it is presumed that intermolecular utilization occurs between the alkali metal perchlorate and the block copolymer, and the alkali metal perchlorate is stabilized.
In addition, this stabilization preferably includes water, and the decomposition start temperature of the paste-like conductive composition containing 13% by weight or less of water increases. If the content of water is more than 13% by weight, the surface resistance changes with time when applied as an antistatic agent for plastics.

As the cation of the alkali metal perchlorate used in the present invention, sodium, potassium, lithium, and cesium are used, but lithium is preferable from the viewpoint of good solubility. Alkali metal perchlorate should be added in an amount of 8% by weight to 25% by weight
If it is less than 8% by weight, the stabilizing effect is small, and if it is more than 25% by weight, it is difficult from the viewpoint of solubility.

The block copolymer of polyethylene glycol and polypropylene glycol has an ethylene oxide content of 10 mol% or more and 50 mol% or less. If the content of ethylene oxide exceeds 50 mol%, it becomes a solid state and handling is inconvenient. Ethylene oxide content of 10
If it is less than mol%, the solubility of the alkali metal perchlorate will be low.

The molecular weight of the polypropylene glycol is preferably from 1,000 to 2,000. If it is less than 1000, the solubility in water increases, and if it is more than 2000, the solubility of the alkali metal perchlorate decreases.

The paste-form conductive composition of the present invention thus obtained is used for batteries, capacitors, electrolytes such as electrochromic displays, carrier tapes for electronic parts such as ICs and LSIs, antistatic agents for plastics, and antifogging agents. To be served.

The stabilized paste-form conductive composition according to the present invention can be used by dissolving it in an organic solvent such as ethanol, methyl ethyl ketone or toluene.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

Examples 1, 2, 3, 4 A block copolymer of polyethylene glycol and polypropylene glycol having a molecular weight of polypropylene glycol of 1200 and an ethylene oxide chain content in the copolymer molecule of 50 mol% was obtained.

The polymer was heated to 90 ° C., and an appropriate amount of lithium perchlorate (anhydrous) was added and dissolved to obtain a paste-like conductive composition comprising lithium perchlorate and a block copolymer. 8% by weight of lithium perchlorate (Example 1), 15% by weight
(Example 2), 20% by weight (Example 3), and 25% by weight (Example 4), the composition was subjected to differential thermal analysis using a closed cell to measure the decomposition onset temperature. Table 1 shows the measurement results. For reference, the decomposition start temperature of the block copolymer alone is also shown.

Comparative Example 1 Example 1 was followed except that the addition amount of lithium perchlorate was changed to 6% by weight. Table 1 shows the decomposition onset temperatures.

When the addition amount of lithium perchlorate is 8% by weight or more, the decomposition start temperature increases as the addition amount increases. 6% by weight has no effect.

Comparative Example 2 Example 1 was followed except that the amount of lithium perchlorate added was 28% by weight. Lithium perchlorate did not dissolve uniformly and a paste-like conductive composition could not be obtained.

Examples 5 and 6 When the content of ethylene oxide chains in the copolymer molecule was 10
The procedure was the same as in Example 1 except that the mol% (Example 5) and 20 mol% (Example 6) were used. Table 1 shows the decomposition onset temperatures.

Examples 7, 8, and 9 A block copolymer of polyethylene glycol and polypropylene glycol having a molecular weight of polypropylene glycol of 1750 and an ethylene oxide chain content of 10 mol% in the copolymer was obtained.

The copolymer is heated to 60 ° C., anhydrous or water-containing lithium perchlorate is added and dissolved, and a paste-like conductive composition comprising anhydrous or water-containing lithium perchlorate and a block copolymer I got The decomposition onset temperatures of the compositions containing 0% by weight (Example 7), 5% by weight (Example 8) and 13% by weight (Example 9) were measured. The results are shown in Table 2 together with the composition of each component.

Comparative Example 3 A paste-like conductive composition was obtained in the same manner as in Example 7, except that water was 15 g, lithium perchlorate was 10 g, the copolymer was 75 g, and the water content was 15 wt%. When kneaded with polyvinyl chloride as an antistatic additive, the conductivity decreased with time and could not be used.

Examples 10 and 11 The procedure of Example 1 was repeated except that sodium perchlorate (anhydrous) (Example 10) and potassium perchlorate (anhydrous) (Example 11) were used as the alkali metal perchlorate. Table 3 shows the decomposition onset temperatures.

(Effect of the Invention) The paste-like conductive composition of the present invention is thermally stabilized and has a high thermal decomposition temperature and a low risk of explosion, so that it is easy to handle.

In particular, those containing lithium perchlorate have high conductivity and are transparent, so that they can be used for electrolytes such as batteries and as antistatic agents for plastics requiring transparency.

Further, since the content of polyethylene glycol, which is hydrophilic, is low, even when kneaded into plastic as an antistatic agent, there is no extraction with water, and the characteristics do not change with time. Further, by containing an appropriate amount of water, the thermal decomposition temperature further rises and is safe.

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C09D 5/00, 5/24, 171/02

Claims (3)

(57) [Claims] 1. An alkali metal perchlorate of not less than 8% by weight and not less than 25% by weight.
A block copolymer of polyethylene glycol and polypropylene glycol containing not more than 10% by weight, wherein the content of ethylene oxide chains in the copolymer molecule is from 10 mol% to 50 mol%. Composition. 2. The conductive composition according to claim 1, wherein the alkali metal perchlorate is lithium perchlorate. 3. The conductive composition according to claim 1, which contains 13% by weight or less of water.