JPH0625110B2 - Heat resistant charge transfer complex - Google Patents

Description

TECHNICAL FIELD The present invention relates to a charge transfer complex having excellent conductivity and heat resistance. The present invention also relates to a solid electrolytic capacitor using the above charge transfer complex.

(Prior Art) In recent years, with the development of digital equipment, there is an increasing demand for a large-capacity capacitor having a low impedance in a high frequency region and an excellent high frequency characteristic.

Conventionally, films, mica, and ceramic capacitors have been used as capacitors having excellent high frequency characteristics, but when the capacity is increased, the shape becomes larger and the cost becomes higher.

Further, electrolytic capacitors as large-capacity capacitors include electrolytic solution type and solid electrolyte type using manganese dioxide.
The former has poor capacitor characteristics over time, and also has high frequency characteristics because the electrolyte is ionic conductive. The latter has a high impedance or loss in the high frequency region because the oxide film is easily damaged during the thermal decomposition of manganese nitrate.

In order to solve the above drawbacks of conventional capacitors, 7,7,
An electrolytic capacitor has been proposed which uses 8,8-tetracyanoquinodimethane (hereinafter abbreviated as TCNQ) as an acceptor and a charge transfer complex composed of a combination with various donors as a solid electrolyte. The donor of the proposed TCNQ charge transfer complex is Nn-hexylquinoline, N-ethylisoquinoline, or Nn-butylisoquinoline (Japanese Patent Laid-Open Publication No. 5 (1999) -58242).
8--19144), N-n-amylisoquinoline, or N-isoamylisoquinoline (JP-A-62-1165).
52) and so on.

On the other hand, miniaturization and thinning of electronic devices, and further resource saving have made it necessary to make electronic components into chips.
In this chip component, a land which is a circuit pattern and a terminal of the chip component are soldered by a reflow soldering method or a dip soldering method. Therefore, the TCNQ charge transfer complex is also required to have heat resistance of 230 ° C. or higher.

(Problems to be Solved by the Invention) However, the TCNQ charge transfer complex proposed up to now is thermally melted at a temperature lower than 230 ° C., and if left in this state for a period of time or longer, oxidative decomposition occurs. Therefore, the loss of the capacitor characteristics becomes large especially when soldering,
The conductivity is also lowered and the high frequency characteristics are deteriorated.

An object of the present invention is to solve the above problems, and firstly to provide a charge transfer complex having excellent heat resistance and conductivity, and secondly to use the charge transfer complex as an electrolyte of a capacitor. Another object of the present invention is to provide an electrolytic capacitor having excellent characteristics that can withstand soldering.

(Means for Solving the Problems) As a result of intensive studies conducted by the present inventors for the above purpose, they are represented by the following general formula I. Two 3,5-lutidine alkylene bridges (wherein R represents alkylene having 1 to 12 carbon atoms) are used as a donor,
A heat-resistant charge-transfer complex using 7,7,8,8-tetracyanoquinodimethane as an acceptor solves the above problems, and a capacitor using these complexes as an electrolyte is a solid electrolytic capacitor with excellent heat resistance. After finding out the above, the present invention has been completed.

Next, a method for synthesizing the complex of the present invention will be described. When 3,5-lutidine and alkylene diiodide are reacted in an alcoholic solvent or an acetonitrile solvent to obtain a donor in which N-positions are crosslinked with alkylene, and the donor and TCNQ are reacted in acetonitrile, The heat resistant charge transfer complex of the present invention is obtained.

The corresponding alkylene is straight-chain or branched alkylene having 1 to 12 carbon atoms, but is preferably alkylene having 5 to 8 carbon atoms. Further, it is generally known that the charge transfer complex has a molar ratio of acceptor to donor of 1 or 2, but the molar ratio of the complex of the present invention is 3 to 5,
It is preferably 3.5 to 4.5.

Heat-melting the charge transfer complex thus obtained,
It is impregnated between both electrodes of an element composed of an anode body and a cathode body and then cooled to attach a complex to form a capacitor element, which is incorporated into a solid electrolytic capacitor.

Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 3.24 g of 1,5-diiodo-n-pentane, 2.14 g of 3,5-lutidine and 5 ml of acetonitrile were placed in a flask equipped with a reflux condenser and a stirrer and reacted under reflux for 1 hour. After the reaction was completed, acetonitrile was distilled off under reduced pressure,
The solid residue was washed twice with 30 ml of ethyl ether to obtain N, N'-pentamethylene-di-3,5-lutidinium-diaiodide (5.29 g) as yellowish white crystals. Next, 120 ml of acetonitrile and 4.25 g of TCNQ were placed in a four-necked flask equipped with a reflux condenser and a stirrer and heated, and N, N '
40 ml of an acetonitrile solution in which 4.2 g of -pentamethylene-di-3,5-lutidinium-diaiodide was dissolved was added dropwise, and the mixture was refluxed for 20 minutes. After cooling the reaction solution, the precipitated crystals were separated by filtration and washed twice with 50 ml of methyl alcohol to obtain 5.33 g of N, N'-pentamethylene-di-3,5-rutidinium.TCNQ complex.

The results of elemental analysis of the complex are shown below.

Elemental analysis value C ₆₇ H ₄₄ N ₁₈ Calculated value: C%: 73.08, H%: 4.03, N%: 22.89 Actual value: C%: 73.14, H%: 4.01, N%: 22.85 Further, a thermal analyzer was used. Results of differential thermal analysis (Fig. 1),
The melting point of the complex was 247 ° C, and the exothermic decomposition point was 263 ° C. The infrared absorption spectrum of this complex is shown in FIG.

Examples 2-4 1 mol of 3,5-lutidine and 1/2 mol of 2,4-diiodine
n-Pentane, 1,6-diiodo-n-hexane and 1,8-diiodo-n-octane are each reacted in acetonitrile according to Example 1 to obtain the corresponding diiodide. The TCNQ charge transfer complex was synthesized in accordance with Example 1 below, and the melting point and exothermic decomposition point were measured from the results of differential thermal analysis using a thermal analyzer, and the results are shown in Table 1. The differential thermal analysis data and infrared absorption spectrum of the corresponding complex are shown in Fig. 2 and Fig. 7, N, N for N, N'-1,3-dimethyltrimethylene-di-3,5-rutidinium-TCNQ complex. ′
-Hexamethylene-di-3,5-lutidinium / TCNQ
The complex is shown in FIGS. 3 and 8, and the N, N'-octamethylene-di-3,5-rutidinium.TCNQ complex is shown in FIGS. 4 and 9, respectively.

Comparative Example 1 1.84 g of n-butyl iodide and 1.29 g of quinoline were reacted in acetonitrile according to Example 1 and then Nn-butylquinolinium TCN was obtained according to Example 1.
The Q complex was synthesized, and the melting point and exothermic decomposition point were measured from the differential thermal analysis data (FIG. 5) using a thermal analyzer, and the results are shown in Table 1. The infrared absorption spectrum is shown in FIG.

From Table 1, it can be seen that the complexes having two 3,5-lutidines having N-positions cross-linked with alkylene as a donor have a uniformly high melting point of 230 ° C. or higher, and the N-n Since the exothermic decomposition point is higher than that of the -butylquinolinium complex or the conventionally known complex, it was found that the thermal stability is extremely excellent.

Examples 5 to 8 60 mg of each of the complexes obtained in Examples 1 to 4 was filled in an aluminum case having a diameter of 6.3 mm, dissolved by heating to immerse a wound aluminum electrolytic capacitor unit, and immediately cooled to obtain a capacitor. It was As the capacitor unit, an aluminum surface was subjected to chemical conversion treatment to form an oxide film, and the capacitor unit was preheated before immersion. The characteristics of the obtained capacitor are shown in the column before the heat resistance test in Table 2. Next, this capacitor was put together with the case in a solder bath at 230 ° C. for 30 seconds and left at room temperature, and the capacitor characteristics were measured again. This value is shown in the column after the heat resistance test in Table 2.

Comparative Example 2 A capacitor was prepared from the complex obtained in Comparative Example 1 according to Examples 5 to 8 and the capacitor characteristics before and after the heat resistance test were measured. The results obtained are shown in Table 2.

In Table 2, Cap is capacitance (μF) at 20 ° C. and 120 Hz, tan δ is dielectric loss tangent (%) at 20 ° C. and 120 Hz, and ESR is equivalent series resistance (mΩ) at 20 ° C. and 100 KHz. △ C / C is 85 for 20 ° C
This is the change rate (%) of the electrostatic capacity at ° C.

From Table 2, it was found that the characteristics of the capacitors made of the complexes shown in the examples after being placed in the solder bath did not change much compared to the initial characteristics, and showed excellent capacitor characteristics.

(Effect of the invention) The charge transfer complex of the present invention, which has TCNQ as an acceptor and a donor in which two N-positions of two 3,5-lutidines are bridged with alkylene, has a melting point of 230 ° C or higher, and the thermal stability is remarkably improved. Was done. In addition, the solid electrolytic capacitor using the complex of the present invention as an electrolyte exhibits heat resistance that can withstand soldering, and therefore has a small loss, a low conductivity, and a high frequency characteristic.

[Brief description of drawings]

1 to 4 and 6 to 9 show a first embodiment of the present invention.
4 is the differential thermal analysis data and infrared absorption spectrum of the complexes, and FIGS. 5 and 10 are the differential thermal analysis data and infrared absorption spectrum of the complex obtained in Comparative Example 1.

Claims (2)

[Claims] 1. A general formula I (However, R represents an alkylene having 1 to 12 carbon atoms), an alkylene crosslinked product of two 3,5-lutidines is used as a donor, and 7,7,8,8-tetracyanoquinodimethane is used as an acceptor. Heat resistant charge transfer complex. 2. A heat-resistant solid electrolytic capacitor using the heat-resistant charge transfer complex according to claim 1 as an electrolyte.