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Preparation method of ADC (azodicarbonamide) foaming agent with uniform grain diameter

A kind of ADC foaming agent, uniform technology, applied in the field of preparation of ADC foaming agent, can solve the problems of short decomposition process, delayed foaming, large specific surface area, etc., to achieve the effect of avoiding difficulties

Active Publication Date: 2013-12-11
HANGZHOU HI TECH FINE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The use of a foaming agent with a wide particle size distribution will cause many difficulties in the foaming process: the ADC foaming agent with a small particle size that exists in a foaming agent with a wide particle size distribution has a large specific surface area, strong activity, and a short decomposition process. , it is bound to foam in advance, resulting in high defective and reject rate of foamed products
The ADC foaming agent with large particle size, due to its small specific surface area, weak activity, and long decomposition process, will inevitably delay foaming or even not foam, making the surface of foamed products turn yellow, seriously affecting the color of foamed products and quality

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] 1. Preparation of ultrafine ADC foaming agent powder:

[0017] The ADC foaming agent is pulverized by high-speed airflow through a high-speed airflow pulverizer to obtain ultrafine ADC foaming agent powder with an average particle size of 3-4 μm.

[0018] 2 Add the superfine ADC foaming agent powder seed crystal to the reaction system:

[0019] Add 100 g of biurea to 1000 ml of water to form a suspension, add sulfuric acid to make the acidity 3N, then add 2 g of potassium bromide as a catalyst, stir and raise the temperature to 60°C.

[0020] Then add 20 grams of ultrafine ADC blowing agent powder with an average particle size of 3-4 μm as seed crystals.

[0021] 3. Synthesis of ADC blowing agent with uniform particle size

[0022] 32 grams of sodium chlorate was subjected to oxidation reaction at a reaction temperature of 60°C to prepare ADC foaming agent with uniform particle size.

Embodiment 2

[0024] 1 Preparation of ultrafine ADC foaming agent powder:

[0025] The ADC foaming agent is classified by a classifier to obtain ultrafine ADC foaming agent powder with an average particle size of 4-5 μm.

[0026] 2 Add the superfine ADC foaming agent powder seed crystal to the reaction system:

[0027] Add 150 g of biurea into 1000 ml of water to form a suspension, add hydrochloric acid to make the acidity 4N, and then add 3 g of sodium bromide as a catalyst, stir and raise the temperature to 50°C.

[0028] Finally, 75 grams of ultrafine ADC foaming agent powder with an average particle size of 4-5μm is added as a seed crystal.

[0029] 3. Synthesis of ADC blowing agent with uniform particle size

[0030] Adding 180 ml of 27.5% hydrogen peroxide for oxidation reaction, the reaction temperature is 50 DEG C, the uniform particle size ADC foaming agent is prepared.

Embodiment 3

[0032] 1 Preparation of ultrafine ADC foaming agent powder:

[0033] The ultrafine ADC foaming agent powder with an average particle size of 5-6μm obtained from the cyclone trap behind the pulverizer is used.

[0034] 2 Add the superfine ADC foaming agent powder seed crystal to the reaction system:

[0035] Add 200 grams of biurea into 1000 milliliters of water to form a suspension. Add hydrochloric acid to make the acidity at 5N, then add 4g of potassium bromide as a catalyst, stir and raise the temperature to 40°C.

[0036] Finally, 150 grams of ultrafine ADC foaming agent powder with an average particle size of 5-6 μm is added as a seed crystal.

[0037] 3. Synthesis of ADC blowing agent with uniform particle size

[0038] Chlorine gas is used to carry out the oxidation reaction, and the reaction temperature is 40°C until the oxidation reaction is complete, and the ADC blowing agent with uniform particle size is prepared.

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Abstract

The invention provides a preparation method of ADC (azodicarbonamide) foaming agent with uniform grain diameter, which comprises the following steps: (1) preparing superfine ADC foaming agent powder with the average grain diameter of 3-6 microns; (2) adding biurea into water to prepare suspension containing 8-32wt% of biurea, adding inorganic acid to control the acidity to be 2-8N, adding potassium bromide or sodium bromide catalyst, controlling the concentration of the catalyst to be 1-5g / l, stirring and heating up to 20-65 degrees centigrade, and then adding the superfine ADC foaming agent powder which is 5-100% of the mass of biurea to serve as seed crystals; (3) adding an oxidant to carry out oxidization reaction to prepare the ADC foaming agent with uniform grain diameter, wherein the reaction temperature is 20-65 degrees centigrade. The preparation method provided by the invention has advantages as follows: the ADC foaming agent with uniform grain diameter can be directly prepared in a process of oxidizing biurea to prepare the ADC foaming agent; the foaming agent is capable of effectively avoiding a difficult foaming process caused by over wide grain diameter distribution of the foaming agent, and is particularly suitable for the foaming production having a higher requirement on the granularity distribution of the foaming agent, such as process for continuously foaming crosslinked polyethylene foaming sheets (XPE and IXPE).

Description

Technical field [0001] The invention relates to the field of ADC foaming agents, and is mainly a preparation method of ADC foaming agents with uniform particle size. Background technique [0002] The chemical name of ADC foaming agent is azodicarbonamide. It has the advantages of non-toxic and odorless, stable at room temperature, large gas generation, and no pollution to products. It is a chemical foaming agent with the widest application range and the largest usage. Used in the foaming of thermoplastic resins such as polyvinyl chloride, polyethylene, polystyrene, ethylene-vinyl acetate, natural rubber, butyl rubber, styrene butadiene rubber, and silicone rubber. However, the ADC foaming agents produced on the market now have the problem of excessively wide particle size distribution of the foaming agent. Using a blowing agent with a too wide particle size distribution will cause many difficulties in the foaming process: the blowing agent with a too wide particle size distribut...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C281/20
Inventor 谢雪源陈海贤
Owner HANGZHOU HI TECH FINE CHEM