CN106397828A - Recycling method of polyethylene in superfine fiber preparation - Google Patents

Abstract

The invention discloses a method for recovering and reusing polyethylene in the preparation of superfine fibers. Part of the solid waste in the production of superfine fibers is crushed and soaked in hydrochloric acid; the pretreated solids are treated with a compound organic solvent. Extraction, while adding some auxiliary agents, extraction; the remaining solids after extraction are added to the toluene solution, and then heated at a controlled temperature until the solids are completely dissolved; the adsorption column equipped with XDA‑1 macroporous adsorption resin is placed in a constant temperature box, through The adsorption column is cooled, and high-purity polyethylene is precipitated.

Description

Method for recovery and reuse of polyethylene in the preparation of superfine fibers

technical field

The invention relates to a method for recycling chemical material waste, in particular to a method for recycling polyethylene in the preparation of superfine fibers.

Background technique

When preparing ultrafine fibers, when using toluene to leach polyethylene, the toluene solution contains polyethylene, silicone oil or polyurethane and other leaching substances. At present, the treatment method of microfiber production enterprises for toluene leachate is mainly to concentrate it and reuse the obtained toluene, but the solid waste containing polyethylene obtained after concentration is generally sold directly at a low price.

Contents of the invention

The purpose of the present invention is to provide a method for recycling polyethylene in the preparation of ultrafine fibers, which separates and purifies polyethylene in solid waste to obtain high-purity polyethylene, and reuses it as a raw material, thereby Reduce the raw material cost of the enterprise and improve the competitiveness of the enterprise.

To achieve the above object, the solution of the present invention is:

A method for recovering and reusing polyethylene in the preparation of superfine fibers, the steps comprising:

Step 1, taking part of the solid waste in the production of superfine fibers and crushing, then soaking the crushed matter with 4%-8% hydrochloric acid, the mass ratio of the crushed matter to hydrochloric acid is 1:4;

Step 2. Extract the solid pretreated in step 1 with a compound organic solvent for silicone oil, and add additives at the same time. The heating temperature during extraction is 70-100°C, and the extraction time is 1-3 hours;

Step 3. Add the remaining solid extracted in step 2 into the toluene solution with a mass ratio of 1:5-10, then control the temperature at about 40-80°C, heat until all the solids are dissolved, and keep the temperature constant for 30-80 minutes;

Step 4. Put the adsorption column equipped with XDA-1 macroporous adsorption resin in a constant temperature box, adjust the temperature of the constant temperature box to 40-80°C, and pass the 40-80°C constant temperature solution in step 3 through the adsorption column, After cooling, high-purity polyethylene is precipitated.

The soaking time of the step 1 is 10-15 hours.

The mass ratio of the solid to the composite organic solvent in the step 2 is about 1:8-12.

The auxiliary agent is oleic acid or Tween-80, and the volume ratio of the auxiliary agent to the composite organic solvent is 1:6-12.

After adopting the above scheme, the working principle of the present invention is:

In the production of ultrafine fibers, the main components of solid waste are mixed silicone oil, polyurethane and polyethylene. Since polyurethane is insoluble in toluene, its content in toluene leachate is very low, and polyurethane is also one of the raw materials for preparing ultrafine fibers. Therefore, when recycling polyethylene, the focus is on how to separate polyethylene from mixed silicone oil.

(1) Properties of silicone oil and polyethylene

(a) Silicone oil usually refers to a linear polysiloxane product that maintains a liquid state at room temperature. It is generally divided into two types: methyl silicone oil and modified silicone oil. Its structure is shown in Figure 1. The most commonly used silicone oil is monomethyl silicone oil, also known as ordinary silicone oil, whose organic groups are all methyl groups, and methyl silicone oil has good chemical stability, good insulation and hydrophobic properties. Silicone oil is insoluble in water, methanol, glycol and -ethoxyethanol, miscible with benzene, dimethyl ether, methyl ethyl ketone, carbon tetrachloride or kerosene, slightly soluble in acetone, dioxane, ethanol and butanol .

(R is alkyl, aryl, R' is alkyl, aryl, hydrogen, etc.; X is alkyl, aryl,, hydrogen, hydroxyl, etc.; n, m=0, 1, 2, 3...)

(b) Polyethylene is the polymer with the simplest structure, which is formed by addition polymerization of ethylene (CH ₂ =CH ₂ ) and linked by repeating –CH ₂ – units. At present, the polyethylene used in the production of microfibers is generally low-density polyethylene (LDPE), which is free radically polymerized under high pressure (100-300MPa), high temperature (190-210°C), and peroxide catalyzed conditions. Compounds with branched chain structures were obtained. Polyethylene is insoluble in any known solvents at room temperature, and can be dissolved in a small amount in solvents such as toluene, amyl acetate, and trichloroethylene above 70°C. Polyethylene has excellent chemical stability, and is resistant to corrosion by various chemical substances such as hydrochloric acid, hydrofluoric acid, phosphoric acid, formic acid, amines, sodium hydroxide, and potassium hydroxide at room temperature, but nitric acid and sulfuric acid have strong corrosion effects on polyethylene. destructive effect.

(2) Comparison of the properties of silicone oil and polyethylene

The mixed silicone oil used in the production of microfiber, whether it is methyl silicone oil or modified silicone oil, has the following two main differences from polyethylene:

The structure of silicone oil is linear, while that of polyethylene is branched.

Silicone oil contains a variety of hydrophobic substituents such as alkyl groups and aryl groups, and its hydrophobicity is greater than that of polyethylene.

(c) Silicone oil has poorer acid and alkali resistance than polyethylene.

(3) Separation mechanism of silicone oil and polyethylene

(a) Pulverize the microfiber waste and pretreat it with hydrochloric acid to destroy the structure of the silicone oil to a certain extent.

(b) Purification of solid waste with mixed reagents.

(c) Based on the polarity difference between polyethylene and silicone oil, a small amount of silicone oil in polyethylene solution is adsorbed by macroporous adsorption resin, so that the purity of recovered polyethylene is further improved.

Description of drawings

Fig. 1 is the schematic flow chart of the recycling process of polyethylene in the production of microfibers of the present invention.

detailed description

As shown in Figure 1, the present invention discloses a method for recycling polyethylene in the preparation of ultrafine fibers, the specific steps of which include:

Step 1, take part of the solid waste in the production of superfine fibers and pulverize, then soak the pulverized material with 4%-8% hydrochloric acid, the soaking time is 10-15 hours, and the mass ratio of the pulverized material to hydrochloric acid is 1: 4;

Step 2, the pretreated solid in step 1 is extracted with silicone oil with a composite organic solvent, the mass ratio of the solid to the composite organic solvent is about 1:8-12, and an auxiliary agent is added at the same time, and the auxiliary agent is oleic acid or Tween- 80, the volume ratio of additives and compound organic solvents is 1:6~12, the heating temperature during extraction is 70-100°C, and the extraction time is 1~3 hours;

Step 3. Add the remaining solid extracted in step 2 into the toluene solution with a mass ratio of 1:5-10, then control the temperature at about 40-80°C, heat until all the solids are dissolved, and keep the temperature constant for 30-80 minutes;

Step 4. Put the adsorption column equipped with XDA-1 macroporous adsorption resin in a constant temperature box, adjust the temperature of the constant temperature box to 40-80°C, and pass the 40-80°C constant temperature solution in step 3 through the adsorption column, After cooling, high-purity polyethylene is precipitated.

Example 1:

Step 1. Take 20 grams of solid waste in the production of superfine fibers and crush them, then soak the crushed matter with 100 milliliters of 5.0% hydrochloric acid for about 12 hours;

Step 2. Extract the pretreated solid in step 1 with 200 ml of toluene-ethanol composite organic solvent with a volume ratio of 1:1 (the composite organic solvent contains about 20 ml of Tween-80). The heating temperature is about 90°C, and the extraction time is about 1 hour;

Step 3. Add the remaining solid extracted in step 2 into the toluene solution with a mass ratio of 1:8, then control the temperature at about 60°C, heat until the solid is completely dissolved, and keep the temperature constant for 30 minutes;

Step 4. Put the adsorption column equipped with XDA-1 macroporous adsorption resin in a constant temperature box, adjust the temperature of the constant temperature box to about 60°C, and pass the 60°C constant temperature solution in step 3 through the adsorption column, and cool it down, that is High-purity polyethylene was precipitated.

Example 2:

Step 1. Take 20 grams of solid waste in the production of superfine fibers and crush them, then soak the crushed matter with 100 milliliters of 5.0% hydrochloric acid for about 12 hours;

Step 2. Extract the pretreated solid in step 1 with 200 milliliters of toluene-acetone composite organic solvent with a volume ratio of 1:1 (the composite organic solvent contains about 20 milliliters of oleic acid), and the heating temperature during extraction About 90°C, the extraction time is about 1 hour;

Step 3. Add the remaining solid extracted in step 2 into the toluene solution with a mass ratio of 1:8, then control the temperature at about 60°C, heat until the solid is completely dissolved, and keep the temperature constant for 30 minutes;

Step 4. Put the adsorption column equipped with XDA-1 macroporous adsorption resin in a constant temperature box, adjust the temperature of the constant temperature box to about 60°C, and pass the 60°C constant temperature solution in step 3 through the adsorption column, and cool it down, that is High-purity polyethylene was precipitated.

The above is only an embodiment of the present invention, and does not limit the technical scope of the present invention in any way. Therefore, any minor modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the present invention. within the scope of the technical program.

Claims (4)

1. a method for recovering and reusing polyethylene in the preparation of superfine fibers, the steps comprising: Step 1, taking part of the solid waste in the production of superfine fibers and crushing, then soaking the crushed matter with 4%-8% hydrochloric acid, the mass ratio of the crushed matter to hydrochloric acid is 1:4; Step 2. Extract the solid pretreated in step 1 with a compound organic solvent for silicone oil, and add additives at the same time. The heating temperature during extraction is 70-100°C, and the extraction time is 1-3 hours; Step 3. Add the remaining solid extracted in step 2 into the toluene solution with a mass ratio of 1:5-10, then control the temperature at about 40-80°C, heat until all the solids are dissolved, and keep the temperature constant for 30-80 minutes; Step 4. Put the adsorption column equipped with XDA-1 macroporous adsorption resin in a constant temperature box, adjust the temperature of the constant temperature box to 40-80°C, and pass the 40-80°C constant temperature solution in step 3 through the adsorption column, After cooling, high-purity polyethylene is precipitated. 2. The method for recycling polyethylene in the preparation of ultrafine fibers according to claim 1, characterized in that: the soaking time of the step 1 is 10-15 hours. 3. The recycling method of polyethylene in the preparation of microfiber as claimed in claim 1, characterized in that: the mass ratio of solid and composite organic solvent in step 2 is about 1:8-12. 4. the recycling method of polyethylene in the microfiber preparation as claimed in claim 1, is characterized in that: the auxiliary agent in described step 2 is oleic acid or Tween-80, the mixture of auxiliary agent and composite organic solvent The volume ratio is 1:6~12.