CN110818842A

CN110818842A - Reaction method of vinyl acetate monomer and grafted polyethylene matrix

Info

Publication number: CN110818842A
Application number: CN201810901902.0A
Authority: CN
Inventors: 张海瑜; 孙伟; 张中超
Original assignee: Yanya Branch Of Shandong Ruifeng Polymer Materials Co Ltd
Current assignee: Yanya Branch Of Shandong Ruifeng Polymer Materials Co Ltd
Priority date: 2018-08-09
Filing date: 2018-08-09
Publication date: 2020-02-21

Abstract

The invention relates to a reaction method of vinyl acetate monomer and grafted polyethylene matrix, wherein the reaction monomers are vinyl acetate and polyvinyl ester, and the specific method comprises the following steps: under the action of an initiator, a vinyl acetate monomer and a polyethylene matrix are subjected to grafting reaction to prepare grafted polyethylene with a functional group on a side chain. The preparation method of the invention can produce polyethylene with high melt strength by a polyethylene graft modification method, and has the advantages of excellent performance, low cost and high productivity.

Description

Reaction method of vinyl acetate monomer and grafted polyethylene matrix

Technical Field

The invention relates to an organic chemical product, in particular to a reaction method of a vinyl acetate monomer and a grafted polyethylene matrix.

Background

The polyethylene is a thermoplastic resin prepared by polymerizing ethylene, has a saturated main chain structure, excellent low-temperature resistance (the lowest use temperature can reach-70 to-100 ℃), good chemical stability, resistance to most of acid-base erosion (resistance to acid with oxidation property), insolubility in common solvents at normal temperature, small water absorption and excellent electrical insulation performance. The polyethylene has good low-temperature toughness and high cost performance, and is widely applied to modification of non-polar plastics such as polypropylene and the like. However, polyethylene is a non-polar material, and in order to further widen the application field of polyethylene and meet the application requirements of polar plastics or fillers, polyethylene needs to be chemically modified, i.e., a functional group is introduced into the main chain of a polyethylene molecule, so as to improve the chemical properties of polyethylene. The preparation method of the invention can produce polyethylene with high melt strength by a polyethylene graft modification method, and has the advantages of excellent performance, low cost and high productivity.

Disclosure of Invention

The invention aims to provide a method for grafting and modifying polyethylene so as to greatly improve the chemical properties of the polyethylene.

In order to achieve the purpose, the invention adopts the following technical scheme: a method for grafting and modifying polyethylene comprises the following steps:

A. preparation of grafted polyethylene

Under the action of an initiator, carrying out grafting reaction on a vinyl acetate monomer and a polyethylene substrate to prepare grafted polyethylene with a functional group on a side chain;

the raw materials and the weight portion ratio in the step A are as follows:

80-90 parts of a polyethylene matrix;

5-15 parts of vinyl acetate;

0.5-5 parts of an initiator.

The grafting reaction in the step A adopts a solution grafting reaction:

the solution grafting reaction is: adding various materials except the initiator into dimethylbenzene or chloroform, gradually heating and stirring to form a uniform solution with the polyethylene content of 5-15%, introducing nitrogen to remove oxygen, gradually adding the initiator for 3-5 times, maintaining the reaction for 2-4 hours, cooling the reaction solution after the reaction is finished, separating out solids, and filtering and drying to obtain grafted polyethylene;

in the solution grafting reaction, if the reaction temperature is lower than 100 ℃, the polyethylene may be incompletely dissolved, making the grafting reaction difficult to proceed. If the reaction temperature is too high, the solvent is vigorously boiled so that the grafting reaction cannot be stably conducted.

The polyethylene substrate is selected from one or more of high density polyethylene, low density polyethylene and linear low density polyethylene. The melt flow rate is between 0.1g/10min and 50g/10 min. Too large or too small a melt flow rate is disadvantageous for the grafting reaction of the polyethylene resin, thereby reducing the reaction efficiency.

The grafting monomer is vinyl acetate.

The initiator is selected from one or more of dicumyl peroxide, benzoyl peroxide and azobisisobutyronitrile. Too high or too low an amount of the initiator may reduce the reaction efficiency of polyethylene grafting and affect the use performance of the polyethylene grafting.

The invention is further illustrated by the following examples:

example 1:

80 parts of polyethylene (melt index: 8.0 g/10 min) was taken, and the mixture was charged into a 2000ml three-neck flask, 800 parts of xylene were added, and the temperature was gradually raised to 130 ℃. After the solid is completely dissolved, 15 parts of vinyl acetate is added, and then 5 parts of benzoyl peroxide are added into the flask in 30min in 5 times, and the reaction is maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Example 2:

85 parts of polyethylene (melt index 8.0 g/10 min) was taken, and the mixture was charged into a 2000ml three-necked flask, and 850 parts of xylene was added thereto, and the temperature was gradually raised to 130 ℃. After the solid was completely dissolved, 10 parts of vinyl acetate was added, and then 5 parts of benzoyl peroxide were added to the flask in 30 minutes 5 times, and the reaction was maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Example 3:

90 parts of polyethylene (melt index 8.0 g/10 min) was taken, and the mixture was put into a 2000ml three-neck flask, 900 parts of xylene was added, and the temperature was gradually raised to 130 ℃. After the solid is completely dissolved, 5 parts of vinyl acetate is added, and then 5 parts of benzoyl peroxide are added into the flask in 30min in 5 times, and the reaction is maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Example 4:

80 parts of polyethylene (melt index: 8.0 g/10 min) was taken, and the mixture was charged into a 2000ml three-neck flask, 800 parts of xylene were added, and the temperature was gradually raised to 130 ℃. After the solid was completely dissolved, 15 parts of vinyl acetate was added, and then 10 parts of benzoyl peroxide was added to the flask in 5 portions over 30min, and the reaction was maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Example 5:

80 parts of polyethylene (melt index: 8.0 g/10 min) was taken, and the mixture was charged into a 2000ml three-neck flask, 800 parts of xylene were added, and the temperature was gradually raised to 130 ℃. After the solid is completely dissolved, 15 parts of vinyl acetate is added, and then 12 parts of benzoyl peroxide are added into the flask in 5 times within 30min, and the reaction is maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Example 6:

80 parts of polyethylene (melt index: 8.0 g/10 min) was taken, and the mixture was charged into a 2000ml three-neck flask, 1000 parts of xylene was added, and the temperature was gradually raised to 130 ℃. After the solid is completely dissolved, 15 parts of vinyl acetate is added, and then 5 parts of benzoyl peroxide are added into the flask in 30min in 5 times, and the reaction is maintained at 130 ℃. After the reaction is finished, cooling the flask to room temperature, adding 100 parts of acetone, stirring until the solid is completely separated out, and drying in a vacuum oven to obtain the grafted polyethylene.

Tests show that 80 parts of polyethylene forms a 10% uniform solution, 15 parts of vinyl acetate and 5 parts of benzoyl peroxide are added and reacted for 4 hours at 130 ℃, and the obtained grafted polyethylene has the highest melt strength and the best performance.

Claims

1. A method for grafting and modifying polyethylene is characterized by comprising the following steps:

A. preparation of grafted polyethylene

the process for the graft modification of polyethylene according to claim 1, wherein: the raw materials and the weight portion ratio in the step A are as follows:

80-90 parts of a polyethylene matrix;

5-10 parts of vinyl acetate;

0.5-5 parts of an initiator.

2. The process for the graft modification of polyethylene according to claim 1, wherein: the grafting reaction in the step A adopts a solution grafting reaction:

the solution grafting reaction is: adding various materials except the initiator into toluene or chloroform, gradually heating and stirring to form a uniform solution with the polyethylene content of 10-15%, introducing nitrogen to remove oxygen, gradually adding the initiator for 3-5 times, maintaining the reaction for 2-4 hours, cooling the reaction solution after the reaction is finished, separating out solids, and filtering and drying to obtain the grafted polyethylene.

3. Process for the graft modification of polyethylene according to claim 1 or 2 or 3, characterized in that: the polyethylene substrate is selected from one or more of high density polyethylene, low density polyethylene and linear low density polyethylene.

4. The melt flow rate is between 0.1g/10min and 50g/10 min.

5. Process for the graft modification of polyethylene according to claim 1 or 2 or 3, characterized in that: the grafting monomer is vinyl acetate.

6. Process for the graft modification of polyethylene according to claim 1 or 2 or 3, characterized in that: the initiator is selected from one or more of dicumyl peroxide, benzoyl peroxide and azobisisobutyronitrile.