JPS6259603A - Impartation of electroconductivity to halogen-containing polymer - Google Patents

Abstract

PURPOSE:To impart excellent electroconductivity to a halogen-containing polymer by a simple treatment, by treating the polymer with sulfur trioxide. CONSTITUTION:A halogen-containing polymer such as polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinyl acetate copolymer or tetra fluoroethylene/propylene fluoroelastomer is prepared. Excellent electro conductivity is imparted to this halogen-containing polymer by treatment with sulfur trioxide. Examples of such a treatment include one comprising contacting a solid polymer with a vapor of sulfur trioxide or a solution containing sulfur trioxide and one comprising dissolving a polymer in a solvent inert to sulfur trioxide and either blowing a vapor of sulfur trioxide into the solution or dissolv ing sulfur trioxide in the solution.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for making a halogen-containing polymer conductive.

(Prior art) As a method for preparing a polyene polymer by dehydrochlorinating a halogen-containing polymer such as polyvinyl chloride, the halogen-containing polymer is dispersed in an aqueous medium containing an inorganic base such as sodium hydroxide and heated under pressure. A method of dehalogenation or dehydrohalogenation (JP-A-49-112979), in which a salt-containing silane polymer is heated to 160 to 500C in water MU such as sodium hydroxide to which an acid amide as a catalyst is added. method (JP-A-58-142905), a method of producing deno-hydrogenation of a halogen-containing polymer using an alkaline aqueous solution and a phase transfer catalyst (/# JP-A-58-142905), 150 in the presence of concentrated sulfuric acid over 904
A method of dehydrochlorination by heating at a temperature below the boiling point of the sulfuric acid (Japanese Patent Publication No. 55-12552) has been proposed.

(Problems with the prior art) These methods require harsh reaction conditions such as high temperature and high pressure, or the obtained polymer having polyene bonds has insufficient electrical conductivity, or the polymer has poor conductivity. It has problems such as gradually turning red (poor oxidation stability) when left in the air.

(Problems to be Solved by the Invention) The present inventor has conducted intensive studies to develop a method for converting a halogen-containing polymer into a polyene polymer having excellent conductivity using a frR process that does not have such problems. As a result, they discovered that, surprisingly, extremely good electrical conductivity could be obtained by treating a halogen-containing polymer with sulfur trioxide, which is known as a dopant. Based on this knowledge, the present invention was completed. It has arrived.

(Means for Solving the Problems) The present invention provides a method for making a halogen-containing polymer conductive by treating the halogen-containing polymer with sulfur trioxide.

The halogen-containing polymer used in the present invention (7) is a homopolymer of vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; homopolymer,
Copolymer of vinyl halide and vinylidene halide,
- Copolymerization of vinyl halide or vinylidene halide with at least one other monomer copolymerizable with them, such as vinyl acetate, acrylic acid, methacrylic acid, or esters of these acids, acrylonitrile, styrene, etc. Coalescing (random, block, graft), polychloroprene, tetrafluoroethylene/globylene fluororubber, vinylidene fluoride/propylene hexafluoride fluororubber, tetrafluoroethylene/barfluoroalkyl perfluorovinyl ether/fluororubber, etc. Examples include fluorine-based rubber, halogenated polymers such as chlorinated polyethylene, and the like. These polymers can be used alone or as a mixture. It can also be used as a mixture of a halogen-containing polymer and a halogen-free polymer, such as a mixture of polyvinyl chloride and ABS resin, or a mixture of polyvinyl chloride and acrylonitrile-butadiene copolymer rubber.

Although the halogen-containing polymer is not limited to the above examples, it is preferable to increase the chain length of the polyene bond in order to increase the conductivity, and it is preferable to increase the chain length of the polyene bond, and it is preferable to use a halogen-containing monomer and a halogen-free monomer. In the copolymer, it is desirable that the chain length of the polymer block of the halogen-containing monomer in the copolymer chain is as long as possible, and the degree of polymerization is preferably as low as 20. The content of the halogen-containing monomer is preferably 10 molar or more.

Examples of the sulfur trioxide used in the present invention include sulfur trioxide, oleum containing sulfur trioxide, and compounds that decompose to produce sulfur trioxide, such as disulfur trioxide.

Treatment of a halogen-containing polymer with sulfur trioxide is accomplished, for example, by contacting the polymer in solid or solution form with sulfur trioxide.

Methods for treating halogen-containing polymers in a solid state (e.g., films, molded articles, powders, etc.) include (1) contacting the polymer with sulfur trioxide vapor; and (2) liquid sulfur trioxide or trioxide. A method such as immersing the polymer in a solution in which sulfur is dispersed or dissolved in a poor solvent for the polymer (a bath agent in which the polymer swells) is an organic or inorganic solvent that does not react with sulfur trioxide. Illustrated.

The method for treating a halogen-containing polymer in an acid solution is as follows: (1) Sulfur trioxide vapor is added to a solution of a halogen-containing polymer (using a solvent for the polymer that does not react with sulfur trioxide). Examples include a method of blowing, and (2) a method of dissolving or dispersing sulfur trioxide in a solution of a halogen-containing polymer.

When treated in the IE liquid state, the polyene polymer precipitates.

The treatment conditions depend on the type of halogen-containing polymer, the a degree of sulfur trioxide, etc., but are usually at room temperature for several seconds to several tens of hours. The processing temperature is not limited to room temperature, but can range from room temperature to 1
This is done in the range of 00C.

Concentrated sulfuric acid treatment at such temperatures should reduce conductivity. Conductivities of 10 to 10-68/3 can be obtained by varying the processing conditions.

After completion of the treatment, the polymer in the form of a film or the separated powder polymer is thoroughly washed with alcohol or water and dried.

The polyene polymer thus obtained has excellent electrical conductivity and is also extremely stable against oxidation.

Furthermore, in order to increase the conductivity, dopant l, which is commonly used, can be doped by chemical doping and electrochemical doping.

As the dopant, known dopants disclosed in % JP-A No. 58-206065 and the like can be used.

The present invention will be specifically explained below using Examples.

Example 1 Polyvinyl chloride (degree of polymerization 1300) film (made by U by solvent casting method, 2o x 20 x length x Q
, 2 m thick) was placed in a glass reaction vessel with a two-way cock, and after degassing with a vacuum pump, SO5 vapor was introduced through a drag cooled with dry ice-methanol.
Saturated with S03 vapor. The experiment was repeated by varying the standing time at room temperature. The film has a rating of 80. It instantly turned black on contact with steam.

For comparison, dehydrochlorination using -8-diazabicyclo[5,4°0]undecene-7 (DBU) was also carried out.

Diisopropyl ether/12-dimethoxyethane (4
/1 weight ratio) The above polyvinyl chloride t-S was dissolved in a mixed solvent, and 5 mol of DBU was added per 1 mol of polyvinyl chloride,
It was treated at 50C for 5 hours under pressure. After the treatment, the precipitated polyene polymer powder was separated, thoroughly washed with methanol, and dried. A sheet having a thickness of α2■ was made by heat pressing.

The conductivity was measured immediately after treatment and after being left in air at 25C for 24 hours using a DC microvoltammeter (PM manufactured by Toa Denpasha).
-18R) at room temperature by the two-terminal method.

The results are shown in Table 1.

Table 1 Note) (1) Untreated film (2) DBU treatment After removing unreacted polyvinyl chloride from the test piece of Experiment No. 4 by washing with dimethoxyethane, elemental analysis was performed. As a result, the polymer obtained by treating polyvinyl chloride with 803 had the following structure (the number in the formula is 31! (ffil, ↓ indicates doping).

Example 2 A film of vinyl chloride and vinegar picopolymer (vinyl acetate content 23%) was treated with SO5 vapor for 20 hours as in Example 1. The conductivity of the film after treatment was determined as in Example 1. It was measured and a result of 1.8 x 10-2B/cm was obtained.

Example 3 50's of ABS resin and PVC resin.

lit ratio) mixture (Zeon Kasei product AL~4003)
(20 length x 20 length x Q, 5M thickness) was treated with SO5 steam for 20 hours in the same manner as in Example 1.

The conductivity after treatment was 5.5 x 10-28/c+a.

Claims (1)

[Claims] A method for making a halogen-containing polymer conductive, the method comprising treating the halogen-containing polymer with sulfur trioxide.