CN1321637A - Preparation method of tellurium diethyl dithiocarbamate - Google Patents

Abstract

A preparation method of tellurium diethyldithiocarbamate uses tellurium oxide as raw material and adopts the following steps: using caustic alkali to dissolve tellurium oxide, controlling a certain reaction condition, making alkaline solution of tellurium and sodium diethyldithiocarbamate produce reaction to prepare and obtain homogeneous phase tellurium diethyl dithiocarbamate with uniform grain size. Said method is simple and convenient in operation, and easy to implement.

Description

The preparation method of tellurium diethyldithiocarbamate

The invention relates to a preparation method of tellurium diethyldithiocarbamate.

Tellurium diethyldithiocarbamate, TDEC for short, is an additive in the production process of EPDM rubber products. Its structural formula is:

Because EPDM rubber has excellent ozone resistance, high thermal stability (485°C), good heat aging resistance, weather resistance, chemical resistance, oil resistance and excellent electrical insulation properties, it is mainly used in Heat-resistant conveyor belts, wires, cables, gaskets, etc. Tellurium diethyldithiocarbamate (TDEC) is a rapid vulcanization accelerator belonging to the dithiocarbamate class. It can not only improve the vulcanization efficiency of EPDM rubber, reduce energy consumption, but more importantly, it can improve the quality of products. Excellent foaming uniformity and mechanical strength. Therefore, TDEC is an important additive in the production of ternary isopropyl rubber products.

At present, TDEC is generally obtained by reacting soluble tellurium salt with sodium diethyldithiocarbamate. However, due to the poor stability of soluble tellurium salts such as tellurium sulfite and tellurium tetrachloride, they are easily hydrolyzed into tellurium oxide, and diethyldithiocarbamate in a homogeneous phase cannot be obtained when reacting with sodium diethyldithiocarbamate. Tellurium Carbamate. Therefore, in the production process of the ternary isopropyl rubber product, the usage amount increases due to the reduction of the effective components in the auxiliary agent, which increases the production cost of the product and wastes resources.

The purpose of the present invention is to provide a new method for preparing tellurium diethyldithiocarbamate, the method will be able to obtain tellurium diethyldithiocarbamate of homogeneous phase, thereby can overcome the existing problems of the prior art the aforementioned deficiencies.

Technical concept of the present invention is such:

The present invention uses tellurium oxide with good stability as raw material, dissolves tellurium oxide with caustic alkali such as sodium hydroxide or potassium hydroxide, and then controls certain reaction conditions to prepare by reacting tellurium alkaline solution with sodium diethyldithiocarbamate A homogeneous phase and uniform particle size tellurium diethyldithiocarbamate are obtained.

The technical scheme that realizes the object of the present invention:

Said method of the present invention comprises the steps:

① Preparation of tellurium solution:

Tellurium oxide is dissolved with lye to make a solution of tellurium, and the concentration of lye is 0.1-2moll ^-1 . When the alkali concentration is less than 0.1moll ^-1 , tellurium oxide cannot be completely dissolved in the caustic solution; and when it is greater than 2moll ^-1 , the formed tellurate is easy to precipitate, and a uniform tellurium alkaline solution cannot be obtained;

The concentration of tellurium in the alkaline solution of tellurium has no substantial influence on the next reaction, but generally 0.02～0.08moll ^-1 is appropriate;

Said alkali includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate;

Preferred is sodium hydroxide or potassium hydroxide;

②Synthesis of tellurium diethyldithiocarbamate:

The alkali solution of tellurium obtained by step 1. is reacted with sodium diethyldithiocarbamate, and the reaction conditions are as follows:

pH=7～11, reaction temperature 20～80℃;

During the reaction process of the alkaline solution of tellurium and sodium diethyldithiocarbamate, the pH is controlled between 7 and 11. If the pH is less than 7, the alkaline solution of sodium diethyldithiocarbamate and tellurium is easy to decompose, and tellurium diethyldithiocarbamate cannot be obtained; if the pH is greater than 11, tellurium cannot be completely precipitated, and the yield decreases.

pH control can be achieved by adding a pH regulator, such as adding a pH buffer solution, inorganic acids such as hydrochloric acid, acetic acid, nitric acid, etc.;

The reaction temperature is 20-80°C. If the reaction temperature is lower than 20°C, the reaction will not be complete, and the yield of TDEC will decrease; if the reaction temperature is higher than 80°C, the reaction speed will be too fast, and TDEC gel will be formed, which will increase the difficulty of post-processing, and Uneven particle size;

Sodium diethyldithiocarbamate is preferably first prepared into a solution, and the concentration is preferably 5-20wt%;

③Separation:

TDEC is separated from the reaction mixture by conventional methods, such as filtration, washing, drying and the like.

The TDEC obtained by the above-mentioned disclosed preparation method can obtain tellurium diethyldithiocarbamate in a homogeneous phase, which provides conditions for reducing the production cost of ternary isopropyl rubber products, and it can be seen from the above-mentioned disclosed technical scheme, The method of the invention has the advantages of simple operation and easy implementation, and the yield can be higher than 96%.

The present invention will be further described by way of examples below.

Example 1

Add 40g _TeO2 into 500ml 1mol l ^-1 NaOH solution and heat until _TeO2 is completely dissolved. Take 10% (wt) 2260g sodium diethyldithiocarbamate solution, control the reaction temperature to 50°C, add the above-mentioned NaOH solution of tellurium dropwise to the sodium diethyldithiocarbamate solution under stirring condition. During the dropwise addition, the pH of the system was adjusted between 8 and 9 with borax-dipotassium hydrogen phosphate buffer solution (pH 8.4), and the bright yellow precipitate was TDEC. After washing by filtration and vacuum drying at 80°C, 182g of TDEC was obtained, with a tellurium content of 16.9%, a melting point of 110-118°C, and a particle size of 2-10 μm.

Example 2

Add 40g _TeO2 into 1000ml 0.5mol l ^-1 KOH solution and heat until _TeO2 is completely dissolved. Take a 10% (wt) 2260 g sodium diethyldithiocarbamate solution, control the reaction temperature to 50° C., and add it dropwise into the KOH solution of tellurium under the condition of stirring. During the dropwise addition, adjust the pH of the system to 8-10 with 0.1mol l ^-1 HCl, and the bright yellow precipitate is TDEC. After filtration and washing, vacuum drying at 80°C yielded 177.5 g of TDEC with a tellurium content of 18%, a melting point of 113-117°C, and a particle size of 2-8 μm.

Example 3

Using the same operating method as in Example 1, replacing NaOH with a mixed solution of KOH and NaOH (1:1 by mass), 174 g of TDEC was obtained, wherein the tellurium content was 18.5%, the melting point was 113-117° C., and the particle size was 2-8 μm.

Example 4

Using the same operating method as in Example 1, sodium carbonate solution was used instead of NaOH to obtain 160 g of TDEC, wherein the tellurium content was 19.5%, the melting point was 113-117° C., and the particle size was 2-8 μm.

Example 5

Using the same operating method as in Example 1, potassium carbonate solution was used instead of NaOH to obtain 161 g TDEC, wherein the tellurium content was 19.0%, the melting point was 113-117° C., and the particle size was 2-8 μm.

Claims (8)

1. the preparation method of a tellurium diethyl dithiocarbamate is characterized in that, comprises the steps:

1. the preparation of tellurium solution: with alkali lye dissolved oxygen tellurium, the concentration of alkali lye is 0.1～2moll ^-1

2. tellurium diethyl dithiocarbamate is synthetic: the condition and the Thiocarb of alkaline solution in pH=7～11 of the tellurium that 1. step is obtained reacts;

3. separate: adopt conventional method from reaction mixture, to separate TDEC.

2. the method for claim 1 is characterized in that, said alkali comprises one or more in sodium hydroxide, potassium hydroxide, yellow soda ash, salt of wormwood, sodium bicarbonate or the saleratus.

3. method as claimed in claim 2 is characterized in that, said alkali is sodium hydroxide or potassium hydroxide.

4. the method for claim 1 is characterized in that, 2. step adds the pH of pH regulator agent with control solution in the building-up process of tellurium diethyl dithiocarbamate.

5. the method for claim 1 is characterized in that, said pH regulator agent comprises pH buffered soln or mineral acid.

6. the method for claim 1 is characterized in that, the concentration of tellurium is 0.02～0.08moll in the alkaline solution of tellurium ^-1

7. the method for claim 1 is characterized in that, Thiocarb concentration is the solution of 5～20wt%.

8. as the arbitrary described method of claim 1～7, it is characterized in that temperature of reaction is 20～80 ℃.