CN116554601A - A method for improving the processing fluidity of polypropylene - Google Patents

Abstract

The invention belongs to the technical field of polymer materials, and in particular relates to a method for improving the processing fluidity of polypropylene. Conventional PP materials synthesized by traditional Ziegler-Natta catalysts have high relative molecular weight and wide relative molecular weight distribution, and poor processing fluidity. In view of the above problems, the present invention provides a method for improving the processing fluidity of polypropylene, which pretreats the peroxide with a volatile organic solvent, so that the PP and the peroxide are mixed more uniformly, and the melt of the obtained modified material Mobility is significantly improved.

Description

A method for improving the processing fluidity of polypropylene

technical field

The invention belongs to the technical field of polymer materials, and in particular relates to a method for improving the processing fluidity of polypropylene.

Background technique

Polypropylene (PP) is a polymer material polymerized from propylene as a monomer. It has low density, non-toxicity, easy processing, impact resistance, flexure resistance, good electrical insulation, and relatively good mechanical properties. PP material can also be recycled.

Conventional PP materials are synthesized by traditional Ziegler-Natta catalysts. Due to the wide active point of the catalyst system, PP materials have high relative molecular mass and wide relative molecular mass distribution, high melt viscoelasticity, and poor processing fluidity.

Studies have shown that adding a small amount of peroxide to PP materials can adjust the fluidity of PP resin. This method can improve the melt flow index of PP materials to a certain extent and improve its processing fluidity. However, since the peroxide cannot be well dispersed, the processing fluidity of the obtained PP material needs to be further improved.

Contents of the invention

The problems in the prior art are: the conventional PP material synthesized by the traditional Ziegler-Natta catalyst has a high relative molecular mass and a wide relative molecular mass distribution, and poor processing fluidity. In view of the above problems, the present invention provides a method for improving the processing fluidity of polypropylene, comprising the following steps:

(1) at room temperature, the peroxide is completely dissolved in the volatile organic solvent, the mass ratio of the peroxide to the volatile organic solvent is (1-10): (90-99), to obtain a premixed solution;

(2) Add an appropriate amount of PP to the premix obtained in step (1), stir and mix evenly, the mass ratio of the PP to the peroxide in the premix is (99-99.9):(0.1-1), and obtain Pretreatment of PP modified materials;

(3) removing the volatile organic solvent in the pretreated PP modified material obtained in step (2), obtaining the PP modified material to be processed;

(4) Putting the modified PP material obtained in step (3) into an extruder for extrusion granulation to obtain a polypropylene material with improved processing fluidity.

Specifically, the peroxide includes at least one of benzoyl peroxide, dicumyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane .

Specifically, the volatile organic solvent includes at least one of absolute ethanol, benzene, chloroform, and ether.

Specifically, the PP is an isotactic homopolymer or a random copolymer.

Specifically, the extruder extruded pelletizing temperature is 180-220°C.

The present invention has following beneficial effect:

The present invention pretreats the peroxide with a volatile organic solvent, so that the PP resin and the peroxide are mixed more uniformly, and after removing the volatile organic solvent in the mixed modified material at high temperature, the peroxide can be more uniformly mixed with the PP resin In combination, the processing fluidity of the obtained modified material is significantly improved.

Detailed ways:

The present invention will be described in detail below in conjunction with the examples. However, it should be understood that the following examples are only illustrations of the embodiments of the present invention, rather than limiting the scope of the present invention.

The PP resin used in the following examples of the present invention is the same as that of Comparative Example 1.

Example 1

A method for improving the processing fluidity of polypropylene, the steps are as follows:

(1) at room temperature, dicumyl peroxide is completely dissolved in absolute ethanol, and the mass ratio of said dicumyl peroxide to absolute ethanol is 10:99 to obtain a premixed solution;

(2) Add an appropriate amount of PP to the premixed solution obtained in step (1), and stir and mix for 2 hours at 200 rpm. The mass ratio of the PP to the peroxide in the premixed solution is 99:1 to obtain a pretreated PP modified material ;

(3) placing the pretreated PP modified material obtained in step (2) in a blast drying oven at 80° C., removing the absolute ethanol in the pretreated PP modified material, and obtaining the PP modified material to be processed;

(4) Put the modified PP material obtained in step (3) into an extruder for extrusion granulation, and the extrusion temperature is 180° C. to obtain a polypropylene material with improved processing fluidity.

Example 2

A method for improving the processing fluidity of polypropylene, the steps are as follows:

(1) At room temperature, benzoyl peroxide is completely dissolved in absolute ethanol, the mass ratio of said benzoyl peroxide to absolute ethanol is 1:90, to obtain a premix;

(2) Add an appropriate amount of PP to the premixed solution obtained in step (1), and stir and mix for 2 hours at 200 rpm. The mass ratio of the PP to the benzoyl peroxide in the premixed solution is 99.5:0.5, and the pretreated PP improved sexual material;

(3) placing the pretreated PP modified material obtained in step (2) in a blast drying oven at 80° C., removing the absolute ethanol in the pretreated PP modified material, and obtaining the PP modified material to be processed;

(4) Put the modified PP material obtained in step (3) into an extruder for extrusion and granulation, and the extrusion temperature is 220°C to obtain a polypropylene material with improved processing fluidity.

Example 3

A method for improving the processing fluidity of polypropylene, the steps are as follows:

(1) At room temperature, completely dissolve 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane in absolute ethanol, the 2,5-dimethyl-2, The mass volume ratio of 5-bis(tert-butylperoxy)hexane and absolute ethanol is 5:95 to obtain a premixed solution;

(2) Add an appropriate amount of PP to the premix obtained in step (1), and stir and mix at 200rpm for 2 hours. The PP and the 2,5-dimethyl-2,5-bis(tert-butyl peroxide Oxygen group) the mass ratio of hexane is 99.9:0.1, obtains pretreatment PP modified material;

(3) placing the pretreated PP modified material obtained in step (2) in a blast drying oven at 80° C., removing the absolute ethanol in the pretreated PP modified material, and obtaining the PP modified material to be processed;

(4) Put the PP modified material to be processed obtained in step (3) into an extruder for extrusion granulation, and the extrusion temperature is 210° C. to obtain a polypropylene material with improved processing fluidity.

Example 4 is the same as Example 1, except that the volatile organic solvent used in Example 4 is diethyl ether, and its step (3) is to place the pretreated PP modified material obtained in step (2) at 80 ° C. In the blast drying oven, the absolute ethanol in the pretreated PP modified material is removed to obtain the PP modified material to be processed.

Example 5 is the same as Example 1, except that the volatile organic solvent used in Example 5 is chloroform, and its step (3) is to place the pretreated PP modified material obtained in step (2) at 80 ° C. In the blast drying oven, the absolute ethanol in the pretreated PP modified material is removed to obtain the PP modified material to be processed.

Example 6 is the same as Example 1, except that the volatile organic solvent used in Example 6 is benzene, and the step (3) is to place the pretreated PP modified material obtained in step (2) at 80 ° C. In the blast drying oven, the absolute ethanol in the pretreated PP modified material is removed to obtain the PP modified material to be processed.

Comparative example 1 is a pure PP general material synthesized by Ziegler-Natta catalyst, and its melt flow index is 6.95g/10min.

Comparative Example 2 is the same as Example 1, except that the PP material obtained in Comparative Example 2 is prepared according to the following steps:

Stir and mix PP and dicumyl peroxide at 200rpm for 2 hours according to the mass ratio of 99:1, then put the obtained modified material in an extruder for extrusion granulation, and the extrusion temperature is 180°C to obtain Polypropylene material.

Comparative Example 3 is the same as Comparative Example 2, except that in Comparative Example 3, PP and dicumyl peroxide were stirred and mixed at 200 rpm for 12 hours at a mass ratio of 99:1.

Comparative Example 4 is the same as Comparative Example 2, except that in Comparative Example 4, PP and dicumyl peroxide were stirred and mixed at 200 rpm for 24 hours at a mass ratio of 99:1.

Comparative Example 5 is the same as Comparative Example 2, except that in Comparative Example 5, PP and dicumyl peroxide were stirred and mixed at 200 rpm for 48 hours at a mass ratio of 99:1.

Performance Testing

According to the ISO 1133-1 standard, the melt flow index test was performed on the polypropylene materials obtained in Examples 1-6 of the present invention and comparative examples, and the specific test results are shown in Table 1.

Table 1

Test items The mass ratio of PP to peroxide Melt flow index (g/10min) Example 1 99:1 4.26 Example 2 99.5:0.5 3.77 Example 3 99.9:0.1 3.21 Example 4 99:1 4.25 Example 5 99:1 4.25 Example 6 99:1 4.26 Comparative example 1 100:0 3.06 Comparative example 2 99:1 3.54 Comparative example 3 99:1 3.80 Comparative example 4 99:1 3.80 Comparative example 5 99:1 3.80

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (5)

1. A method for improving the processing flowability of polypropylene comprising the steps of:

(1) At room temperature, completely dissolving peroxide in a volatile organic solvent, wherein the mass ratio of the peroxide to the volatile organic solvent is (1-10) (90-99) to obtain a premix;

(2) Adding a proper amount of PP into the premix obtained in the step (1), and uniformly stirring and mixing, wherein the mass ratio of the PP to the peroxide in the premix is (99-99.9) (0.1-1), so as to obtain a pretreated PP modified material;

(3) Removing the volatile organic solvent in the pretreated PP modified material obtained in the step (2) to obtain the PP modified material to be processed;

(4) And (3) placing the PP modified material to be processed obtained in the step (3) into an extruder for extrusion granulation, and obtaining the polypropylene material with improved processing fluidity.

2. A method of improving the processing flowability of polypropylene according to claim 1, wherein the peroxide comprises at least one of benzoyl peroxide, dicumyl peroxide, 2, 5-dimethyl-2, 5-bis (t-butylperoxy) hexane.

3. The method for improving the processing flowability of polypropylene according to claim 1, wherein the volatile organic solvent comprises at least one of absolute ethyl alcohol, benzene, chloroform and diethyl ether.

4. A method of improving the processing flowability of polypropylene according to claim 1, wherein the PP is an isotactic homopolymer or a random copolymer.

5. A method for improving the processing flowability of polypropylene according to claim 1, wherein the temperature of extrusion granulation by an extruder is 180-220 ℃.