CN112708020B

CN112708020B - Maleic anhydride terpolymer microsphere and preparation method and application thereof

Info

Publication number: CN112708020B
Application number: CN201911024610.4A
Authority: CN
Inventors: 宋文波; 刘振杰; 张洁; 袁浩
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2019-10-25
Filing date: 2019-10-25
Publication date: 2023-02-28
Anticipated expiration: 2039-10-25
Also published as: CN112708020A

Abstract

The invention relates to the field of preparation of polymer microspheres and discloses a maleic anhydride terpolymer microsphere, wherein a copolymer in the terpolymer microsphere comprises a structural unit shown in a formula (1), a structure shown in a formula (2) and a structural unit shown in a formula (3);

the molar content of the structural unit shown in the formula (1) is 48-51%, the molar content of the structural unit shown in the formula (2) is 5-30%, and the molar content of the structural unit shown in the formula (3) is 20-45% based on the total molar amount of all the structural units in the polymer. The maleic anhydride terpolymer microsphere provided by the invention has a clean and pollution-free surface and uniform microsphere particles, is easy to disperse in a polymer processing process when being used as an opening agent for a polyolefin film, and can obviously improve the opening performance of the polyolefin film.

Description

Maleic anhydride terpolymer microsphere and preparation method and application thereof

Technical Field

The invention relates to the field of high molecular polymers, in particular to a maleic anhydride terpolymer microsphere and a preparation method and application thereof.

Background

In the prior art, the maleic anhydride-containing copolymers are mostly prepared by solution or conventional precipitation polymerization. Shenrong et al, in "Styrene-maleic anhydride copolymerization in different solvents" disclose that maleic anhydride and styrene were reacted in ethyl acetate and N, N-dimethylformamide, and after completion of the reaction, a polymer of maleic anhydride and styrene was prepared by using ethanol as a precipitant (Wuhan university Proc., 2019, 41 (1): 65-68).

In "Synthesis of styrene-maleic anhydride alternating copolymer with Low relative molecular weight" in Liuting, et al, styrene-maleic anhydride copolymer was synthesized by precipitation polymerization in toluene.

Synthesis and characterization of styrene-maleic anhydride random copolymer in Green solvent of Gekko Swinhonis et al (plastics science 2019, 47 (2): 24-28) styrene-maleic anhydride random copolymer was prepared by solution polymerization using dimethyl carbonate as a Green solvent.

Multipolymers of maleic anhydride have many uses. The study of Liangshujun et al on an alpha-methylstyrene/styrene/maleic anhydride terpolymer functional polypropylene and compatibilized polypropylene/nylon 6 blending system, the report on high polymer, 2011,2: 180-185' using butanone as solvent to synthesize the terpolymer of maleic anhydride, styrene and alpha-methyl styrene, and the terpolymer has in-situ compatibilization effect on the polypropylene/nylon 6 blending system, so that the particle size of the dispersed phase nylon 6 is obviously reduced.

In the prior art, when a polyolefin film is prepared, a large number of exposed molecular chain ends and migrated oligomer micromolecules are arranged on the surface layer of the polyolefin film, and after two layers of films are attached, the leaked molecular chain ends and the micromolecules and the molecular chain ends mutually permeate and entangle, so that the polyolefin film is difficult to open; after the films are tightly attached, the Van der Waals force between molecules is obviously reflected due to the close distance; in the film blowing process, the film forms a vacuum sealing state in the film bubble clamping roller and the winding process, and the films are not easy to separate; along with the increase of the film-making speed, the static accumulation on the surface of the film is increased, and the electrostatic adsorption among films is shown, so that the opening of the polyethylene film is difficult due to the reasons, and the finished product quality and the product percent of pass of the polyolefin film are greatly influenced.

In order to overcome the problem of difficult opening of polymer films, it is generally necessary to add corresponding fillers or auxiliaries to the films. Adding inorganic opening agent to make the surface of the film uneven to increase the film distance and reduce the vacuum degree between films; adding slipping agent to form one layer of slipping agent between two adjacent layers of film to reduce the entanglement of exposed molecular chain ends and reduce the dynamic and static friction coefficient between two layers of film, and adding antistatic agent to eliminate electrostatic adsorption.

However, inorganic opening agents are generally poorly compatible with polymers, and suffer from clumping and difficult dispersion during processing. The addition of slipping agents such as oleamide and other antistatic agents can negatively affect the surface properties of the film and the printing.

Disclosure of Invention

The invention aims to overcome the problem that films are easy to adhere in the preparation process of polyolefin films in the prior art, and provides maleic anhydride terpolymer microspheres and a preparation method and application thereof.

In order to achieve the above object, a first aspect of the present invention provides a maleic anhydride terpolymer microsphere, wherein a copolymer in the terpolymer microsphere comprises a structural unit represented by formula (1), a structure represented by formula (2), and a structural unit represented by formula (3);

the molar content of the structural unit shown in the formula (1) is 48-51%, the molar content of the structural unit shown in the formula (2) is 5-30%, and the molar content of the structural unit shown in the formula (3) is 20-45% based on the total molar amount of all the structural units in the copolymer.

The second aspect of the present invention provides a method for preparing maleic anhydride terpolymer microspheres, comprising the steps of:

(1) Dissolving a polymerization monomer and an initiator in a reaction medium in an inert atmosphere to form a homogeneous solution;

(2) After the homogeneous solution is subjected to polymerization reaction to obtain copolymer emulsion suspension, performing centrifugal separation to obtain the maleic anhydride terpolymer microspheres;

wherein the polymerization monomer is maleic anhydride, a comonomer I and a comonomer II;

the comonomer I has a structure shown as a formula (4)

The comonomer II has a structure represented by the formula (5)

In a third aspect of the present invention, there is provided maleic anhydride terpolymer microspheres prepared by the preparation method of the present invention, wherein the average particle size of the copolymer microspheres is 500-1600nm, preferably 600-1200nm.

The fourth aspect of the invention provides the application of the maleic anhydride terpolymer microspheres as an opening agent in a polyolefin film; preferably, the polyolefin film is a polyethylene film.

Through the technical scheme, the maleic anhydride terpolymer microsphere, the preparation method thereof and the opening agent containing the maleic anhydride terpolymer microsphere provided by the invention have the following beneficial effects:

the maleic anhydride terpolymer microsphere provided by the invention realizes the self-stabilization precipitation polymerization reaction of maleic anhydride, a comonomer II and a comonomer I by selecting a specific reaction medium and matching the specific reaction medium with a specific amount of monomers, the polymerization reaction system does not need to add any stabilizer or co-stabilizer, the self-stabilization dispersion effect is realized, and the obtained polymer microsphere has uniform particle size and clean and pollution-free surface.

Further, the maleic anhydride terpolymer microspheres provided by the invention can be used as an opening agent for polyolefin, particularly for polyethylene, so as to improve the opening performance of a polyethylene film.

Drawings

FIG. 1 is an infrared spectrum of the copolymer of example 1;

FIG. 2 is a scanning electron micrograph of the copolymer of example 1.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.

The invention provides a maleic anhydride terpolymer microsphere, wherein a copolymer in the terpolymer microsphere comprises a structural unit shown as a formula (1), a structure shown as a formula (2) and a structural unit shown as a formula (3);

In the present invention, the total content of the structural unit represented by the formula (1), the structural unit represented by the formula (2), and the structural unit represented by the formula (3) is 100%.

According to the invention, the maleic anhydride and the specific comonomer are copolymerized according to the dosage ratio limited by the invention, so that the obtained maleic anhydride terpolymer has microspheres with good uniformity, and the copolymer has a clean surface, good dispersibility in a medium and no aggregation.

In the invention, the maleic anhydride terpolymer comprises structural units shown in formulas (1) and (3), wherein the maleic anhydride copolymer has the advantages of good balling and good stability due to the introduction of the structural units shown in the formulas (1) and (2).

Furthermore, in order to obtain copolymer microspheres with more excellent performance and more uniform microsphere morphology, the molar content of the structural unit represented by the formula (1) is 48 to 49%, the molar content of the structural unit represented by the formula (2) is 5 to 30%, and the molar content of the structural unit represented by the formula (3) is 22 to 45%, based on the total molar amount of the structural units in the copolymer.

In the present invention, the molar content of each structural unit in the copolymer is used ¹ H NMR is used for testing, and the testing method is to pass ¹ And calculating the ratio of the peak area corresponding to the characteristic hydrogen in the corresponding structural unit in H NMR.

According to the invention, the average particle size of the terpolymer microspheres is 500-1600nm, preferably 600-1200nm.

In the invention, the average particle size of the terpolymer microsphere is 500-1600nm, and the terpolymer microsphere can be used as an opening agent in the field of films, particularly polyethylene films.

(2) After the homogeneous solution is subjected to polymerization reaction to obtain copolymer emulsion suspension, performing solid-liquid separation to obtain the maleic anhydride terpolymer microspheres;

the comonomer I has a structure shown as a formula (4)

The comonomer II has a structure represented by the formula (5)

In the invention, a copolymerization mode is adopted to carry out the copolymerization of the maleic anhydride monomer and a specific comonomer, so that the prepared maleic anhydride terpolymer is in a microspherical shape with excellent uniformity, and the copolymer has the characteristic of clean surface, has good dispersibility in a medium and does not generate aggregation.

In the invention, the maleic anhydride terpolymer is obtained by copolymerizing a maleic anhydride monomer with a comonomer I and a comonomer II. Specifically, the introduction of the comonomer I and the comonomer II ensures that the maleic anhydride copolymer has the advantages of good balling and uniform dispersion.

According to the invention, the mass concentration of the polymerized monomers is from 5 to 25% by weight, preferably from 10 to 20% by weight, based on the total weight of the homogeneous solution;

according to the invention, the maleic anhydride is used in an amount of 46 to 50 wt.%, the comonomer I in an amount of 4 to 26 wt.%, and the comonomer II in an amount of 24 to 50 wt.%, based on the total weight of the polymerized monomers.

In the present invention, the total amount of the maleic anhydride, the comonomer I, the comonomer II, the initiator and the reaction medium is 100wt%

In the invention, in order to obtain the maleic anhydride terpolymer microspheres with uniform particles and excellent morphology, the inventor researches the respective use amounts of maleic anhydride, a comonomer I and a comonomer II in the polymerization process, and researches show that when the respective polymerization monomers meet the ranges, the prepared maleic anhydride terpolymer microspheres have uniform particles, excellent particle morphology and clean particle surfaces, and are used as an opening agent for films, particularly polyethylene films, so that the films have good opening performance.

Still further, the maleic anhydride is used in an amount of 48 to 50wt%, the comonomer I is used in an amount of 5 to 25wt%, and the comonomer II is used in an amount of 25 to 45wt%, based on the total weight of the polymerized monomers.

According to the invention, the initiator is an organic peroxide and/or an azo compound;

according to the present invention, the organic peroxide is at least one selected from the group consisting of dibenzoyl peroxide, dicumyl peroxide, ditert-butyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate.

According to the invention, the azo compound is selected from azobisisobutyronitrile and/or azobisisoheptonitrile.

According to the invention, the mass concentration of the initiator is from 0.05 to 5% by weight, preferably from 1 to 4% by weight, based on the total weight of the homogeneous solution.

According to the invention, the reaction medium is an organic acid alkyl ester.

According to the invention, the organic acid alkyl ester is selected as a reaction medium, and can be matched with the maleic anhydride, the comonomer I and the comonomer II with specific dosage, so that the self-stabilization precipitation polymerization reaction of the maleic anhydride, the comonomer II and the comonomer I can be realized, no stabilizer or co-stabilizer needs to be added into a polymerization reaction system, the self-stabilization dispersion effect is realized, and the surface of the obtained polymer microsphere is clean and pollution-free.

More preferably, the alkyl group is an alkyl group having 1 to 10 carbon atoms, preferably an alkyl group having 1 to 7 carbon atoms.

Still further, the reaction medium is selected from at least one of ethyl formate, propyl formate, isobutyl formate, pentyl formate, ethyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, pentyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate, and ethyl phenylacetate.

In the present invention, the polymerization reaction is carried out in an inert atmosphere, which may be provided by an inert gas conventional in the art, such as nitrogen.

According to the invention, the polymerization conditions comprise: the polymerization temperature is 50-100 ℃, preferably 60-80 ℃; the polymerization time is from 2 to 24 hours, preferably from 4 to 8 hours.

In the present invention, a water bath and/or an oil bath is used to provide the heat required for the polymerization of the present invention.

In the invention, the copolymer emulsion suspension obtained by the polymerization reaction is separated by adopting a solid-liquid separation mode to obtain the maleic anhydride terpolymer microspheres.

In the present invention, a solid-liquid separation method, preferably, centrifugal separation, which is conventional in the prior art, may be employed.

In the invention, when centrifugal separation is adopted, the centrifugal rotating speed is 1000-3000rad/min, and the centrifugal time is 10-30min.

In the present invention, a third aspect of the present invention provides maleic anhydride terpolymer microspheres prepared by the preparation method of the present invention, wherein the average particle size of the copolymer microspheres is 500-1600nm, preferably 600-1200nm.

In the present invention, the maleic anhydride terpolymer microspheres are used in an amount of 0.05 to 1.5wt%, preferably 0.1 to 1wt%, relative to the total weight of the polyolefin.

The present invention will be described in detail below by way of examples. In the following examples of the present invention,

the polymerization yield (C) was determined by the following formula _p ) Perform calculation

Cp＝Mp×100％/Mm

Wherein Mp is the mass of the resulting polymer; mm is the total mass of the monomers added;

observing and measuring the shape and the size of the copolymer microsphere by adopting a Scanning Electron Microscope (SEM);

the infrared spectrogram of the copolymer is tested by FI-IR;

the content of each structural unit in the copolymer is adopted ¹ H NMR is used for testing, and the testing method is to pass ¹ Measuring the content of each structural unit according to the ratio of the peak areas corresponding to the characteristic hydrogen in the corresponding structural unit in H NMR;

the openness of the polyethylene film is measured by a cohesive force tester according to the method of GB 8808-1988;

comonomer I, having the structure of formula (4), was purchased from carbofuran technologies, inc.;

comonomer II, having the structure shown in formula (5), was purchased from carbofuran technologies, inc.

Linear low density polyethylene, designation 1820, available from orthopetrochemical company;

examples and comparative examples all other materials were commercially available.

Example 1

9.8g of maleic anhydride, 0.9g of azobisisobutyronitrile, 5.9g of comonomer II, 4.3g of comonomer I and 87.8g of isoamyl acetate are added into a 500mL three-neck flask, after the materials are uniformly mixed, nitrogen is introduced for 20 minutes, the three-neck flask is moved into a 70 ℃ water bath for reaction for 5 hours, after the reaction is finished, the obtained polymer emulsion suspension is centrifugally separated for 20 minutes by a centrifuge at the rotating speed of 2000rad/min, so that 10.99g of polymer microspheres A are obtained, and the corresponding polymer yield is 54.95%. The polymeric microspheres were 1400 nm in size.

Subjecting the polymeric microspheres A1 to ¹ H NMR measurement, it was determined that the molar content of the structural unit formula (1) was 51%, the molar content of the structural unit formula (2) was 30%, and the molar content of the structural unit formula (3) was 19%, based on the total molar amount of the respective structural units in the polymer.

As can be seen from FIG. 1, 1786cm ^-1 、1890cm ^-1 Characteristic absorption peak of anhydride group, 710cm ^-1 Is a special absorption peak of benzene ring, 1300cm ^-1 Is the stretching vibration peak of C-O, and based on this, the polymer can be determined to be a copolymer of maleic anhydride, alpha-methylstyrene and vinyl acetate.

FIG. 2 is an SEM image of copolymer microspheres, from which it can be seen that the particles of the copolymer microspheres are uniform and the surfaces of the particles are clean and uncontaminated.

Example 2

Adding 10g of maleic anhydride, 0.9g of azobisisobutyronitrile, 7.08g of comonomer II, 3.44g of comonomer I and 87.8g of butyl acetate into a 500mL three-neck flask, uniformly mixing the materials, introducing nitrogen for 20 minutes, moving the three-neck flask into a 70 ℃ water bath, reacting for 5 hours, and after the reaction is finished, centrifugally separating the obtained polymer milky suspension for 20 minutes at the rotating speed of 2000rad/min by a centrifugal machine to obtain 11.88g of polymer microspheres A, wherein the corresponding polymer yield is 58.46%. The size of the polymeric microspheres was 1500 nanometers.

Subjecting polymeric microspheres to ¹ H NMR measurement revealed that the molar content of the structural unit represented by the formula (1) was 48%, the molar content of the structural unit represented by the formula (2) was 15% and the molar content of the structural unit represented by the formula (3) was 37%, based on the total molar amount of the structural units in the polymer.

Example 3

9.8g of maleic anhydride, 0.89g of azobisisobutyronitrile, 8.26g of comonomer II, 2.58g of comonomer I and 87.8g of butyl benzoate are added into a 500mL three-neck flask, after the materials are uniformly mixed, nitrogen is introduced for 20 minutes, the three-neck flask is moved into a 70 ℃ water bath for reaction for 5 hours, after the reaction is finished, the obtained polymer emulsion suspension is centrifugally separated by a centrifuge at the rotating speed of 2000rad/min for 20 minutes to obtain 10.7g of polymer microspheres A, and the corresponding polymer yield is 51.84%. The polymer microspheres were 1600nm in size.

Subjecting the polymer microspheres A3 to ¹ H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 50%, the molar content of the structural unit represented by the formula (2) was 10%, and the molar content of the structural unit represented by the formula (3) was 40%, based on the total molar amount of the structural units in the polymer.

Example 4

10g of maleic anhydride, 0.89g of azobisisobutyronitrile, 9.44g of comonomer II, 1.72g of comonomer I and 87.8g of butyl butyrate are added into a 500mL three-neck flask, after the materials are uniformly mixed, nitrogen is introduced for 20 minutes, the three-neck flask is moved into a 70 ℃ water bath for reaction for 5 hours, after the reaction is finished, the obtained polymer emulsion suspension is centrifugally separated for 20 minutes by a centrifuge at the rotating speed of 2000rad/min, so that 12.9g of polymer microspheres A are obtained, and the corresponding polymer yield is 61.54%. The polymeric microspheres were 1300 nm in size.

Subjecting the polymeric microspheres A4 to ¹ H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 49%, the molar content of the structural unit represented by the formula (2) was 23%, and the molar content of the structural unit represented by the formula (3) was 28%, based on the total molar amount of the structural units in the polymer.

Example 5

9.7g of maleic anhydride, 0.89g of azobisisobutyronitrile, 10.62g of comonomer II, 0.86g of comonomer I and 87.8g of isoamyl acetate are added into a 500mL three-neck flask, after the materials are uniformly mixed, nitrogen is introduced for 20 minutes, the three-neck flask is moved into a water bath at 70 ℃, the reaction is carried out for 5 hours, after the reaction is finished, the obtained polymer emulsion suspension is centrifugally separated for 20 minutes by a centrifuge at the rotating speed of 2000rad/min, and the polymer microsphere A5.5 g is obtained, wherein the corresponding polymer yield is 58.7%. The polymeric microspheres were 1100 nm in size.

Subjecting the polymeric microspheres A5 to ¹ H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 50%, the molar content of the structural unit represented by the formula (2) was 5%, and the molar content of the structural unit represented by the formula (3) was 45%, based on the total molar amount of the structural units in the polymer.

Example 6

9.6g of maleic anhydride, 0.89g of azobisisobutyronitrile, 4.72g of comonomer II, 5.16g of comonomer I and 87.8g of isoamyl acetate are added into a 500mL three-neck flask, after the materials are uniformly mixed, nitrogen is introduced for 20 minutes, the three-neck flask is moved into a 70 ℃ water bath for reaction for 5 hours, after the reaction is finished, the obtained polymer emulsion suspension is centrifugally separated for 20 minutes by a centrifuge at the rotating speed of 2000rad/min, so that 12.1g of polymer microspheres A are obtained, and the corresponding polymer yield is 61.5%. The polymer microspheres have a size of 1000 nm.

The polymer microspheres A6 are subjected to ¹ H NMR measurement of the total based on the individual structural units in the polymerThe molar amount of the structural unit represented by the formula (1) is 50%, the molar content of the structural unit represented by the formula (2) is 25%, and the molar content of the structural unit represented by the formula (3) is 25%.

Example 7

Adding 2.45g of maleic anhydride, 0.21g of azobisisobutyronitrile, 1.18g of comonomer II, 1.29g of comonomer I and 87.8g of isoamyl acetate into a 500mL three-neck flask, uniformly mixing the materials, introducing nitrogen for 20 minutes, transferring the three-neck flask into a 70 ℃ water bath, reacting for 5 hours, and after the reaction is finished, centrifugally separating the obtained polymer emulsion suspension for 20 minutes by a centrifuge at the rotating speed of 2000rad/min to obtain 7g of polymer microspheres A, wherein the corresponding polymer yield is 60.98%. The polymeric microspheres were 500 nanometers in size.

Subjecting the polymeric microspheres A7 to ¹ H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 50%, the molar content of the structural unit represented by the formula (2) was 24%, and the molar content of the structural unit represented by the formula (3) was 26%, based on the total molar amount of the structural units in the polymer.

Comparative example 1

Terpolymer microspheres were prepared according to the method of example 1, except that: acetone is used for replacing isoamyl acetate to obtain a dispersion liquid of the polymer microspheres, and a solution of the polymer is obtained.

Comparative example 2

Terpolymer microspheres were prepared according to the method of example 1, except that: the dosage of maleic anhydride is 20g, the dosage of comonomer II is 10g, the dosage of comonomer I is 20g, after polymerization is finished, a polymerization system is coagulated, and a dispersion system of the polymer microspheres cannot be obtained.

Test example

Extrusion granulation

The polymer microspheres A1 to A7 prepared in examples 1 to 7 were added to high-pressure polyethylene in the amounts shown in Table 1, respectively, and subjected to extrusion granulation under the following experimental conditions: a feeding section is 150-170 ℃; a plasticizing section is 165-200 ℃; the homogenization section is 165-200 ℃; the die head is 160-180 ℃ and the rotating speed is 90-120rad/min.

Blow molding

The films of test examples 1 to 10 in Table 1 were blown with linear low density polyethylene and the above polyethylene pellets under the following conditions, and the resulting films were respectively tested for the opening property, and the results are shown in Table 1.

The film blowing conditions are as follows: zone 1: 140-160 ℃; zone 2, zone 3: 150-170 ℃; zone 4, zone 5: 160-180 ℃; zone 6: 150-170 ℃; the rotating speed is 60-100rad/min.

TABLE 1

Test example	Polymeric microspheres in an amount	Opening force, N/cm
			1	A1，0.8wt％	0.01
2	A1，0.3wt％	0.015
			3	A1，0.1wt％	0.018
4	A2，0.8wt％	0.01
			5	A3，0.8wt％	0.011
6	A4，0.8wt％	0.014
			7	A5，0.8wt％	0.017
8	A6，0.8wt％	0.018
			9	A7，0.8wt％	0.023
10	--	0.025

As shown in Table 1, when the maleic anhydride terpolymer microspheres provided by the invention are added into linear low density polyethylene for film blowing, the prepared film has excellent opening performance.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A maleic anhydride terpolymer microsphere, wherein a copolymer in the terpolymer microsphere comprises a structural unit shown in a formula (1), a structure shown in a formula (2) and a structural unit shown in a formula (3);

formula (1);

formula (2);

formula (3)

2. The terpolymer microspheres according to claim 1, wherein the molar content of the structural unit represented by formula (1) is 48-49%, the molar content of the structural unit represented by formula (2) is 5-30%, and the molar content of the structural unit represented by formula (3) is 22-45%;

in the copolymer, the sum of the contents of the structural units is 100%.

3. The terpolymer microspheres according to claim 1 or 2, wherein the average particle size of the terpolymer microspheres is 500-1600nm.

4. The terpolymer microspheres of claim 1 or 2, wherein the average particle size of the terpolymer microspheres is 600-1200nm.

5. A method for preparing maleic anhydride terpolymer microspheres according to any one of claims 1-4, comprising the steps of:

the comonomer I has a structure shown as a formula (4)

Formula (4);

the comonomer II has a structure represented by the formula (5)

Formula (5);

the mass concentration of the polymerized monomer is 5 to 25wt% based on the total weight of the homogeneous solution;

the reaction medium is an organic acid alkyl ester.

6. The production method according to claim 5, wherein the mass concentration of the polymerized monomer is 10 to 20wt% based on the total weight of the homogeneous solution.

7. The preparation method of claim 5, wherein the maleic anhydride is used in an amount of 46 to 50wt%, the comonomer I is used in an amount of 4 to 26wt%, and the comonomer II is used in an amount of 24 to 50wt%, based on the total weight of the polymerized monomers.

8. The preparation method according to claim 5, wherein the maleic anhydride is used in an amount of 48 to 50wt%, the comonomer I is used in an amount of 5 to 25wt%, and the comonomer II is used in an amount of 25 to 45wt%, based on the total weight of the polymerized monomers.

9. The production method according to claim 5, wherein the initiator is an organic peroxide and/or an azo compound.

10. The production method according to claim 9, wherein the organic peroxide is at least one selected from the group consisting of dibenzoyl peroxide, dicumyl peroxide, di-t-butyl peroxide, lauroyl peroxide, t-butyl peroxybenzoate, diisopropyl peroxydicarbonate, and dicyclohexyl peroxydicarbonate;

and/or, the azo compound is selected from azobisisobutyronitrile and/or azobisisoheptonitrile;

and/or the mass concentration of the initiator is 0.05 to 5wt% based on the total weight of the homogeneous solution.

11. The production method according to claim 10, wherein the mass concentration of the initiator is 1 to 4wt% based on the total weight of the homogeneous solution.

12. The production method according to claim 5, wherein the alkyl group is an alkyl group having 1 to 10 carbon atoms.

13. The production method according to claim 5, wherein the alkyl group is an alkyl group having 1 to 7 carbon atoms.

14. The production process according to claim 5, wherein the reaction medium is at least one selected from the group consisting of ethyl formate, propyl formate, isobutyl formate, amyl formate, ethyl acetate, butyl acetate, isobutyl acetate, sec-butyl acetate, amyl acetate, isoamyl acetate, benzyl acetate, methyl propionate, ethyl propionate, butyl propionate, methyl butyrate, ethyl butyrate, butyl butyrate, isoamyl butyrate, ethyl isovalerate, isoamyl isovalerate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, isoamyl benzoate, methyl phenylacetate and ethyl phenylacetate.

15. The production method according to claim 5, wherein the conditions of the polymerization reaction include: the polymerization temperature is 50-100 ℃; the polymerization time is 2-24h.

16. The production method according to claim 5, wherein the conditions of the polymerization reaction include: the polymerization temperature is 60-80 ℃; the polymerization time is 4-8h.

17. A maleic anhydride terpolymer microsphere obtained by the method of any one of claims 5-16, wherein the copolymer microsphere has an average particle size of 500-1600nm.

18. The maleic anhydride terpolymer microsphere of claim 17, wherein the copolymer microsphere has an average particle size of 600-1200nm.

19. Use of maleic anhydride terpolymer microspheres according to any of claims 1-4 or 17-18 as an opening agent in polyolefin films.

20. Use according to claim 19, wherein the polyolefin film is a polyethylene film.