阅读说明：本技术 马来酸酐/N-苯基马来酰亚胺/α-甲基苯乙烯共聚物微球及其制备方法与应用 (Maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere as well as preparation method and application thereof ) 是由 刘振杰 张洁 宋文波 邹发生 于 2019-10-25 设计创作，主要内容包括：本发明涉及高分子聚合领域,公开了一种马来酸酐/N-苯基马来酰亚胺/a-甲基苯乙烯共聚物微球及其制备方法与应用。所述共聚物微球中的共聚物包含式(1)所示的结构单元、式(2)所示的结构和式(3)所示的结构单元；基于共聚物各结构单元的总摩尔量,所述式(1)所示结构单元的摩尔含量为30-52％,式(2)所述结构单元的摩尔含量为5-30％,式(3)结构单元的摩尔含量为20-45％。共聚物微球表面洁净,且颗粒粒径均匀,制备工艺简单,且所述共聚物微球能够作为耐热改性剂用于聚合物,特别是聚丙烯,提高聚合物的耐热温度。(The invention relates to the field of high polymer polymerization, and discloses maleic anhydride/N-phenylmaleimide/a-methylstyrene copolymer microspheres and a preparation method and application thereof. The copolymer in the copolymer 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 moles of the structural unit represented by the formula (1) based on the total molar amount of the structural units of the copolymerThe content is 30-52%, 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%. The copolymer microsphere has the advantages of clean surface, uniform particle size and simple preparation process, and can be used as a heat-resistant modifier for polymers, particularly polypropylene, to improve the heat-resistant temperature of the polymers.)

1. A maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere, wherein a copolymer in the copolymer 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 30-52%, 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 of the copolymer.

2. The copolymer microspheres of claim 1, wherein the molar content of the structural unit represented by formula (1) is 30 to 50%, the molar content of the structural unit represented by formula (2) is 5 to 25%, and the molar content of the structural unit represented by formula (3) is 20 to 40%, based on the total molar amount of the structural units of the copolymer.

3. The copolymer microsphere according to claim 1 or 2, wherein the average particle size of the copolymer microsphere is 1500-.

4. A method for preparing maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres, the method 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/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres;

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

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

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

The comonomer III has a structure represented by the formula (6)

5. The production method according to claim 4, wherein the mass concentration of the polymerized monomer is 5 to 25 wt%, preferably 10 to 20 wt%, based on the total weight of the homogeneous solution;

preferably, the comonomer I is used in an amount of 30 to 50 wt%, the comonomer II is used in an amount of 20 to 50 wt%, and the comonomer III is used in an amount of 20 to 50 wt%, based on the total weight of the polymerized monomers;

more preferably, the comonomer I is used in an amount of 39 to 45 wt%, the comonomer II is used in an amount of 25 to 42 wt%, and the comonomer III is used in an amount of 19 to 47 wt%, based on the total weight of the polymerized monomers.

6. The production method according to claim 4 or 5, wherein the initiator is an organic peroxide and/or an azo compound;

preferably, the organic peroxide is selected from at least one of dibenzoyl peroxide, dicumyl peroxide, ditert-butyl peroxide, lauroyl peroxide, tert-butyl peroxybenzoate, diisopropyl peroxydicarbonate and dicyclohexyl peroxydicarbonate;

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

preferably, the mass concentration of the initiator is from 0.1 to 4 wt%, preferably from 0.5 to 4 wt%, more preferably from 1 to 3 wt%, based on the total weight of the homogeneous solution.

7. The production method according to any one of claims 4 to 6, wherein the reaction medium is an organic acid alkyl ester;

preferably, the organic acid alkyl ester has the general formula R₁COOR₂Wherein R is₁Selected from H, C_1-4At least one of alkyl, phenyl and benzyl of (A), R₂Is C_1-10Alkyl groups of (a);

more preferably, R₁Is C_1-4Alkyl and/or phenyl of R₂Is C_1-7Alkyl groups of (a);

more preferably, 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.

8. The production method according to any one of claims 4 to 7, wherein the conditions of the polymerization reaction include: the polymerization temperature is 60-90 ℃, preferably 60-80 ℃; the polymerization time is 3 to 24 hours, preferably 4 to 8 hours.

9. Maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres obtained by the method according to any one of claims 4 to 8, wherein the copolymer microspheres have an average particle size of 1500-.

10. Use of maleic anhydride/N-phenylmaleimide/α -methylstyrene copolymer microspheres according to any one of claims 1 to 3 and 9 as a heat resistance modifier in a polymer; preferably, the polymer is polypropylene.

Technical Field

The invention relates to the field of high-molecular polymerization, in particular to maleic anhydride/N-phenylmaleimide/a-methylstyrene copolymer microspheres 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 (proceedings of Wuhan engineering university, 2019, 41 (1): 65-68).

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

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

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

In the prior art, the copolymer containing maleic anhydride is not mentioned as a heat-resistant modifier to be added to a polymer system such as polyolefin.

Disclosure of Invention

The invention aims to solve the problems of polymer surface pollution and environmental pollution caused by addition of auxiliary agents such as reaction solvents, stabilizers and the like in the prior art, and provides maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres and a preparation method and application thereof. The copolymer microsphere has the advantages of clean surface, uniform particle size and simple preparation process, and can be used as a heat-resistant modifier for polymers, particularly polypropylene, to improve the heat-resistant temperature of the polymers.

In order to achieve the above object, a first aspect of the present invention provides maleic anhydride/N-phenylmaleimide/α -methylstyrene copolymer microspheres, wherein a copolymer in the copolymer microspheres 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 30-52%, 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 of the copolymer.

The second aspect of the present invention provides a method for preparing maleic anhydride/N-phenylmaleimide/α -methylstyrene copolymer 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/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres;

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

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

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

The comonomer III has a structure represented by the formula (6)

The third aspect of the invention provides maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres prepared by the preparation method of the invention, wherein the average particle size of the copolymer microspheres is 1500-2500nm, preferably 1500-2000 nm.

The fourth aspect of the invention provides an application of the maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere.

Through the technical scheme, the maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere and the preparation method and application thereof provided by the invention have the following beneficial effects:

the maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere provided by the invention realizes the self-stabilization precipitation polymerization reaction of the comonomer I, the comonomer II and the comonomer III by selecting a specific reaction medium and matching the specific reaction medium with a specific amount of monomers, no stabilizer or co-stabilizer is required to be added into a polymerization reaction system, the polymer microsphere can be dispersed in a continuous phase of a reaction solvent in a suspension state without corresponding agglomeration, and the self-stabilization dispersion of the polymerization system is realized. The obtained polymer microspheres have clean and pollution-free surfaces, can realize the control of the particle size of the microspheres, and obtain the polymer microspheres with the particle size range of 1500-2500 nm.

Furthermore, the composite microsphere provided by the invention can be used as a heat-resistant modifier in polymers, particularly polypropylene, and can improve the heat-resistant temperature of the polymers.

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 ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres, wherein a copolymer in the copolymer microspheres 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 30-52%, 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 the copolymer.

According to the invention, the specific comonomer is copolymerized according to the dosage ratio limited by the invention, so that the obtained maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer has microspheres with good uniformity, and the prepared copolymer microspheres have good dispersibility in a medium, and are not easy to aggregate.

Further, in order to obtain copolymerized microspheres with more excellent properties and more uniform microsphere morphology, the molar content of the structural unit represented by formula (1) is 30 to 50%, the molar content of the structural unit represented by formula (2) is 5 to 25%, and the molar content of the structural unit represented by formula (3) is 20 to 40%, based on the total molar amount of the copolymer.

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

In the present invention, the content of each structural unit in the copolymer is used¹H NMR is used for testing, and the testing method is to pass¹And 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 copolymer microspheres is 1500-2500nm, preferably 1500-2000 nm.

In the invention, the copolymer microsphere has the average particle size of 1500-2500nm, can be used as a heat-resistant modifier to be added into a polymer, and is particularly used as a heat-resistant modifier for polypropylene to improve the heat resistance of the polypropylene.

The second aspect of the present invention provides a method for preparing maleic anhydride/N-phenylmaleimide/α -methylstyrene copolymer 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/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres;

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

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

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

The comonomer III has a structure represented by the formula (6)

In the invention, a copolymerization mode is adopted to carry out copolymerization on a specific comonomer, so that the prepared maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer is in a microspherical shape with excellent uniformity.

In the invention, the maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer is obtained by copolymerizing a comonomer I, a comonomer II and a comonomer III. Specifically, the introduction of the comonomer I and the comonomer II enables the copolymer to form a self-stable dispersion system, and the polymer microsphere material is obtained.

According to the invention, the concentration by mass 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 comonomer I is used in an amount of 30 to 50 wt%, the comonomer II is used in an amount of 20 to 50 wt%, and the comonomer III is used in an amount of 20 to 50 wt%, based on the total weight of the polymerized monomers.

In the invention, in order to obtain maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres with uniform particles and excellent morphology, the inventor researches the respective use amounts of the comonomer I, the comonomer II and the comonomer III in the polymerization process, and the research shows that when the respective polymerization monomers meet the ranges, the prepared terpolymer microspheres have uniform particles, excellent particle morphology and clean particle surfaces, can be used as modified polymers for heat-resistant modifiers, particularly for polypropylene, and can remarkably improve the heat-resistant temperature of the polypropylene.

Still further, the comonomer I is used in an amount of 39 to 45 wt%, the comonomer II is used in an amount of 25 to 42 wt%, and the comonomer III is used in an amount of 19 to 47 wt%, 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 0.1 to 4% by weight, preferably from 0.5 to 4% by weight, more preferably from 1 to 3% by weight, based on the total weight of the homogeneous solution.

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

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

In the invention, organic acid alkyl ester is selected as a reaction medium, and can be matched with the comonomer I, the comonomer II and the comonomer III with specific dosage, so that the self-stabilizing precipitation polymerization reaction of the comonomer I, the comonomer II and the comonomer III can be realized, and the polymerization reaction system does not need to add any stabilizer or co-stabilizer and has a self-stabilizing dispersion effect.

According to the invention, the organic acid alkyl ester has the general formula R₁COOR₂Wherein R is₁Selected from H, C_1-4At least one of alkyl, phenyl and benzyl of (A)，R₂Is C_1-10Alkyl group of (1).

Preferably, R₁Is C_1-4Alkyl and/or phenyl of R₂Is C_1-7Alkyl group of (1).

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.

According to the invention, the polymerization conditions comprise: the polymerization temperature is 60-90 ℃, preferably 60-80 ℃; the polymerization time is 3 to 24 hours, preferably 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/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres.

In the present invention, a solid-liquid separation method, preferably, a centrifugal separation method, 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 10-30 min.

The third aspect of the invention provides maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microspheres prepared by the preparation method of the invention, wherein the average particle size of the copolymer microspheres is 1500-2500nm, preferably 1500-2000 nm.

The fourth aspect of the invention provides an application of the maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer microsphere as a heat-resistant modifier in a polymer; preferably, the polymer is polypropylene.

In the present invention, the maleic anhydride/N-phenylmaleimide/α -methylstyrene copolymer microspheres are used in an amount of 0.1 to 2 wt%, preferably 0.5 to 1.5 wt%, relative to the total weight of the polymer.

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 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 adopted¹H NMR is used for testing, and the testing method is to pass¹Measuring 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 heat resistance of the polypropylene is measured by a GB/T1634.2-2004 method;

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.;

comonomer III, having the structure shown in formula (6), was purchased from carbofuran technologies, Inc.

Examples and comparative examples all other materials were commercially available.

Example 1

10g of comonomer I, 0.8g of azobisisobutyronitrile, 5.9g of comonomer III, 8.65g of comonomer II 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 90 ℃, the reaction is carried out for 3 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, the polymer microsphere A117.89g is obtained, and the corresponding polymer yield is 73.5%. The polymeric microspheres were 1500 nm in size.

Subjecting the polymer microsphere A1 to¹H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 52%, the molar content of the structural unit represented by the formula (2) was 29%, and the molar content of the structural unit represented by the formula (3) was 19%, based on the total molar amount of the structural units in the polymer.

FI-IR chart of copolymer microspheres as shown in FIG. 1, 1785cm^-1、1850cm^-1Characteristic absorption peak of anhydride group, 709cm^-1Is a special absorption peak of a benzene ring, 1020-1300cm^-1Is a characteristic peak of the C-N group, based on which the polymer can be determined to be a maleic anhydride/N-phenylmaleimide/alpha-methylstyrene copolymer.

As shown in the SEM image of the copolymer microsphere in FIG. 2, it can be seen that the particles of the copolymer microsphere are uniform and the surface of the particles is clean and not contaminated.

Example 2

Adding 15g of comonomer I, 0.3g of azobisisobutyronitrile, 7g of comonomer III, 8g of comonomer II and 120g of butyl benzoate into a 500mL three-neck flask, uniformly mixing the materials, introducing nitrogen for 20 minutes, moving the three-neck flask into a water bath at 60 ℃, reacting for 24 hours, and centrifugally separating the obtained polymer milky suspension for 20 minutes by a centrifuge at the rotating speed of 2000rad/min to obtain the polymer microspheres A218.32g, wherein the corresponding polymer yield is 77%. The polymer microspheres were 2000nm in size.

Subjecting the polymer microsphere A2 to¹H 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 30 m%, and the molar content of the structural unit represented by the formula (3) was 22%, based on the total molar amount of the structural units in the polymer.

Example 3

14g of comonomer I, 1.2g of azobisisobutyronitrile, 8g of comonomer III, 8g of comonomer II and 120g 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, and 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 to obtain polymer microspheres A319.2g, wherein the corresponding polymer yield is 82.6%. The polymer microsphere size was 2400 nm.

Subjecting the polymer microsphere A2 to¹H 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 29%, and the molar content of the structural unit represented by the formula (3) was 21%, based on the total molar amount of the structural units in the polymer.

Example 4

Adding 6g of comonomer I, 0.89g of azobisisobutyronitrile, 10g of comonomer III, 4g of comonomer II and 82g of butyl butyrate 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 centrifugally separating the obtained polymer milky suspension for 20 minutes by a centrifuge at the rotating speed of 2000rad/min to obtain polymer microspheres A419.85g, wherein the corresponding polymer yield is 87.4%. The polymer microspheres were 2500nm in size.

Subjecting the polymer microsphere A4 to¹H NMR measurement, it was determined that the molar content of the structural unit represented by the formula (1) was 30%, the molar content of the structural unit represented by the formula (2) was 30%, 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 5

9g of comonomer I, 0.7g of azobisisobutyronitrile, 10.62g of comonomer III, 1.73g of comonomer II and 87.8g of isoamyl 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, polymer microspheres A516.69g are obtained, and the corresponding polymer yield is 75.3%. The polymer microspheres were 2000nm in size.

Subjecting the polymer microsphere A5 to¹H NMR measurement revealed that the molar content of the structural unit represented by the formula (1) was 50% and the molar content of the structural unit represented by the formula (2) was 50%, based on the total molar amount of the structural units in the polymer5% and the molar content of structural units of formula (3) is 45%.

Example 6

Adding 10.1g of comonomer I, 0.89g of azobisisobutyronitrile, 4.72g of comonomer III, 10.38g of comonomer II and 87.8g of isoamyl 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 centrifugally separating the obtained polymer milky suspension for 20 minutes by a centrifuge at the rotating speed of 2000rad/min to obtain 617.15g of polymer microspheres, wherein the corresponding polymer yield is 68.9%. The polymer microspheres had a size of 1800 nm.

Subjecting the polymer microsphere A6 to¹H NMR measurement revealed that the molar content of the structural unit represented by the formula (1) was 52 m%, the molar content of the structural unit represented by the formula (2) was 20%, 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.

Comparative example 1

Copolymers were prepared according to the amounts of the various materials charged in example 1, except that: acetone was used instead of isoamyl acetate. The polymer microspheres can not be obtained, and the solution of the polymer is obtained after the reaction.

Comparative example 2

Copolymer microspheres were prepared according to the method of example 1, except that: the amount of comonomer I was 20g, the amount of comonomer II was 20g and the amount of comonomer III was 10 g. After the reaction is finished, the polymer system is solidified, and the polymer microspheres cannot be obtained.

Test example

The polymer microspheres prepared in the examples and comparative examples were mixed with polypropylene in the amounts shown in table 1, and then subjected to extrusion granulation to obtain polypropylene particles. The rotating speed of the extruder screw is 120r/min, the temperature of the extruder barrel is set to be 175-.

The polypropylene and the polypropylene granules were subjected to a heat resistance temperature test according to GB/T1843-2008, and the test results are shown in Table 1.

TABLE 1

As can be seen from Table 1, the composite microspheres of methylstyrene multipolymers provided by the invention are added to polymers as heat-resistant modifiers, so that the heat-resistant temperature of the polymers can be improved.

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.