CN111849065B

CN111849065B - Foamed polypropylene composition, foamed polypropylene plate and preparation method thereof

Info

Publication number: CN111849065B
Application number: CN201910340215.0A
Authority: CN
Inventors: 郭鹏; 吕明福; 张师军; 解娜; 徐耀辉; 陈若石; 白弈青
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: 2019-04-25
Filing date: 2019-04-25
Publication date: 2021-11-19
Anticipated expiration: 2039-04-25
Also published as: CN111849065A

Abstract

The invention relates to the field of polypropylene foaming materials, and discloses a foaming polypropylene composition, a foaming polypropylene plate and a preparation method thereof. A composition comprising: 100 parts of high melt strength polypropylene, 0.05-2 parts of guanidine salt composite antibacterial agent, 0.05-5 parts of mildew preventive and 1-15 parts of foaming agent; wherein the high melt strength polypropylene comprises the following components: 100 parts of polypropylene, 0.1-0.3 part of antioxidant and 0.25-10 parts of mixed butylene-maleic anhydride copolymer microspheres; wherein the particle size of the copolymer microsphere is 0.1-10 μm. The foamed polypropylene which has compact pores, uniform pore size distribution, smooth surface, high thermal-oxidative aging resistance and non-crosslinking and can be recycled can be prepared by an extrusion molding mode.

Description

Foamed polypropylene composition, foamed polypropylene plate and preparation method thereof

Technical Field

The invention relates to the field of polypropylene foaming materials, in particular to a foaming polypropylene composition, a foaming polypropylene plate and a preparation method thereof.

Background

Polymer foams are composed of very small cells and thin cell films enclosing the cells, and have a high volume fraction of gas, good heat insulation, cushioning properties, floatability, and high cost performance, and thus are widely used. In recent years, polypropylene resin foams have been widely used in the fields of heat-insulating building materials, automobile members, packaging cushioning materials, and the like, because of their excellent balance of performance and cost, and their ability to be recycled. For example, polypropylene resin foamed sheets are widely used in the market as heat insulating building materials because they exhibit excellent heat insulating properties when used in floors and walls of buildings.

The method for preparing polypropylene foam mainly comprises a plate method and an extrusion method. In the former method, polypropylene particles dispersed in water are impregnated with a blowing agent such as carbon dioxide or a hydrocarbon in a pressurized closed container at high temperature and high pressure, and the resulting product is rapidly released under atmospheric pressure to obtain a foamed sheet, which is then molded to obtain a molded product. However, the method is a batch production method, and has the characteristics of complicated manufacturing procedures, various capacities, and incapability of continuous production, so that the manufacturing cost is high. In the latter, polypropylene composition particles are put into an extruder, carbon dioxide, hydrocarbons, chemical foaming agents or crosslinking agents are used according to requirements, and the polypropylene composition particles are subjected to extrusion foaming after being melted and mixed under heating and pressurizing, but a foamed plate obtained by using the carbon dioxide as the foaming agent has high aperture ratio and poor mechanical property; the foaming plate obtained by using the chemical foaming agent has low foaming multiplying power, unobvious weight reduction and narrower application field.

CN101175801A discloses a crosslinked polyolefin resin foam formed from a polyolefin resin composition containing 20 to 50 wt% of a polypropylene resin (A) having at least 1 endothermic peak as measured by a differential scanning calorimeter of 160 ℃ or more, 20 to 50 wt% of a polypropylene resin (B) having an endothermic peak as measured by a differential scanning calorimeter of less than 160 ℃, and 20 to 40 wt% of a polyethylene resin (C). Although the foam has good heat resistance, the polypropylene foam cannot be recycled due to the use of a crosslinking aid during foaming, which is likely to cause environmental pollution.

CN1944032A discloses a method for manufacturing polypropylene foamed sheets, which comprises the following steps: the foaming agent comprises homopolymerized polypropylene, silicon carbonate and AC foaming agent, polypropylene foaming materials with the weight ratio of 70-80, 10-20 and 10-15 are respectively put into a hopper of an extruding machine, the temperature of the extruding machine is raised to 100-280 ℃, the polypropylene foaming materials are smelted, a screw of the extruding machine is started to rotate, the smelted polypropylene foaming materials are extruded from the inside of the hopper to a T-shaped head die with the temperature of 100-280 ℃, the foamed polypropylene foaming materials are extruded to flow to two roller slot wedges of a plate extruding machine set, and are rolled into sheet materials, and the sheet materials are cut into sheets with certain specifications according to requirements after being naturally cooled to room temperature, so that a finished product is obtained. However, the method uses chemical foaming agents such as an AC foaming agent, has low foaming multiplying power, and is not suitable for the field of foaming materials with high requirements on weight reduction.

Therefore, there is a need to provide better methods for preparing polypropylene foams.

Disclosure of Invention

The invention aims to solve the problems that the mechanical property of a material is influenced and the thermal-oxidative aging resistance needs to be improved due to poor forming foam cell quality of a polypropylene foaming material, and provides a foaming polypropylene composition, a foaming polypropylene plate and a preparation method thereof. The provided foamed polypropylene can have compact cells, uniform pore size distribution and smooth surface.

In order to achieve the above object, a first aspect of the present invention provides an expanded polypropylene composition comprising: 100 parts of high melt strength polypropylene, 0.05-2 parts of guanidine salt composite antibacterial agent, 0.05-5 parts of mildew preventive and 1-15 parts of foaming agent; wherein the high melt strength polypropylene comprises the following components: 100 parts of polypropylene, 0.1-0.3 part of antioxidant and 0.25-10 parts of mixed butylene-maleic anhydride copolymer microspheres; wherein the particle size of the copolymer microsphere is 0.1-10 μm.

Preferably, the content of the maleic anhydride structural unit in the mixed butylene-maleic anhydride copolymerized microsphere is 30-70 mol%.

Preferably, the mixed butene-maleic anhydride copolymerized microspheres are a copolymer of maleic anhydride and a carbon tetraene prepared by copolymerizing mixed carbon four and maleic anhydride in the presence of nitrogen, an initiator and an organic solvent.

Preferably, the weight ratio of the mixed C4 to the maleic anhydride is (0.2-3): 1.

preferably, the initiator is used in an amount of 0.05 to 20 mol% based on the maleic anhydride.

Preferably, the copolymerization reaction temperature is 50-100 ℃, the copolymerization reaction pressure is 0.2-2MPa, and the copolymerization reaction time is 5-10 h.

The second aspect of the present invention provides a method for preparing foamed polypropylene, comprising:

(1) mixing 100 parts by weight of polypropylene, 0.1-0.3 part by weight of antioxidant and 0.25-10 parts by weight of mixed butylene-maleic anhydride copolymer microspheres to obtain a blend; extruding and granulating the blend to obtain high-melt-strength polypropylene;

(2) mixing 100 parts by weight of high melt strength polypropylene, 0.05-2 parts by weight of guanidine salt composite antibacterial agent, 0.05-5 parts by weight of mildew preventive and 1-15 parts by weight of foaming agent to obtain premix;

and carrying out extrusion foaming molding on the premix to obtain the foamed polypropylene.

The third aspect of the invention provides a foamed polypropylene sheet prepared by the preparation method.

Through the technical scheme, the foamed polypropylene composition provided by the invention can be prepared into foamed polypropylene with compact pores, uniform pore size distribution, smooth surface and high thermal-oxidative aging resistance in an extrusion molding manner.

Drawings

FIG. 1 is an SEM image of a cross section of expanded polypropylene obtained in example 15 of the present invention;

FIG. 2 is an SEM image of a cross section of expanded polypropylene obtained in example 23.

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 present invention provides in a first aspect a foamed polypropylene composition comprising: 100 parts of high melt strength polypropylene, 0.05-2 parts of guanidine salt composite antibacterial agent, 0.05-5 parts of mildew preventive and 1-15 parts of foaming agent; wherein the high melt strength polypropylene comprises the following components: 100 parts of polypropylene, 0.1-0.3 part of antioxidant and 0.25-10 parts of mixed butylene-maleic anhydride copolymer microspheres; wherein the particle size of the copolymer microsphere is 0.1-10 μm.

Mixed butene-maleic anhydrideCopolymer microspheres

The particle size can be measured by a scanning electron microscope method. The particle size of the copolymer microspheres is preferably 0.2-2 μm.

In the present invention, preferably, the mixed butene-maleic anhydride copolymerized microspheres are maleic anhydride and tetraolefin copolymerized microspheres prepared by copolymerizing mixed C4 and maleic anhydride in the presence of nitrogen, an initiator and an organic solvent. The copolymerization may be a one-step reaction using a precipitation polymerization method. Preferably, the mixed butylene-maleic anhydride copolymer microspheres are copolymer microspheres of maleic anhydride, n-butylene and isobutylene.

In the present invention, preferably, the content of the maleic anhydride structural unit in the mixed butene-maleic anhydride copolymerized microsphere is 30 to 70 mol%. Preferably, the content of maleic anhydride structural units is from 48 to 55 mol%. In the mixed butylene-maleic anhydride copolymer microsphere, the maleic anhydride structural unit can be in a main chain, a side chain or an end group. The content of the maleic anhydride structural unit can be determined by¹H and¹³c nuclear magnetic measurement. The mixed butylene-maleic anhydride copolymer microspheres may further contain olefin structural units formed by at least one of 1-butylene, 1, 3-butadiene and isobutylene. The content of the olefin structural unit in the mixed butylene-maleic anhydride copolymerized microsphere can be determined by¹H and¹³c nuclear magnetic measurement. The olefin building block content may be from 30 to 70 mol%. Preferably, the olefin building block content is from 45 to 52 mol%.

In the present invention, it is preferable that the mixed butene-maleic anhydride copolymerized microspheres contain structural units derived from n-butene and isobutylene mainly in an amount of 30 to 70 mol%, and it is preferable that the structural units derived from n-butene and isobutylene are 45 to 52 mol%.

The mixed butylene-maleic anhydride copolymerized microspheres used in the invention can use mixed C4 as a raw material, wherein the mixed C can be obtained from various petroleum processing and refining processes, and can be C₄A mixture of hydrocarbon compounds. Preferably, the mixed C4 contains 1-butylene, isobutylene and 1, 3-butyleneAt least one of the olefins, n-butane, isobutane, cis-2-butene and trans-2-butene may be, for example, liquefied fuel produced in a petroleum refining process, cracked gas produced by cracking naphtha, gas produced by producing olefins from methanol, and the like. The composition of the mixed C.sub.D can be analyzed by gas chromatography using Agilent's 7890A Gas Chromatograph (GC).

Preferably, the compositional content of the mixed C.sub.D can be 1-99 wt% of 1-butene, 1-99 wt% of isobutylene, 0-99 wt% of 1, 3-butadiene, 0-50 wt% of 1, 2-butadiene, 0-99 wt% of n-butane, 1-99 wt% of isobutane, 5-20 wt% of vinyl acetylene, 0-99 wt% of cis-2-butene, and 1-99 wt% of trans-2-butene.

According to a preferred embodiment of the present invention, the composition content of the mixed C.sub.D may be 5-10 wt% of 1-butene, 5-15 wt% of isobutene, 10-20 wt% of 1, 3-butadiene, 5-15 wt% of 1, 2-butadiene, 0.5-5 wt% of n-butane, 0.5-2 wt% of isobutane, 20-40 wt% of cis-2-butene, 2-10 wt% of trans-2-butene, 5-20 wt% of vinyl acetylene.

According to another preferred embodiment of the present invention, the composition content of the mixed C.sub.D may be 0.1-2 wt% of 1-butene, 10-30 wt% of isobutene, 0.01-0.1 wt% of 1, 3-butadiene, 0.5-5 wt% of n-butane, 30-40 wt% of isobutane, 20-40 wt% of cis-2-butene, 5-20 wt% of trans-2-butene.

According to another preferred embodiment of the present invention, the compositional content of mixed C.sub.D may be 5-15 wt% of 1-butene, 0.5-3 wt% of isobutene, 20-30 wt% of n-butane, 15-30 wt% of cis-2-butene, 35-45 wt% of trans-2-butene.

In the present invention, 1-butene, isobutylene and 1, 3-butadiene among the mixed carbons can be copolymerized with maleic anhydride. Preferably, the weight ratio of the mixed C4 to the maleic anhydride is (0.2-3): 1; preferably (0.8-3): 1.

in the invention, the initiator is used in an amount which ensures that the copolymerization reaction is carried out. Preferably, the initiator is used in an amount of 0.05 to 20 mol% based on the maleic anhydride. The initiator may be dibenzoyl peroxide or azobisisobutyronitrile.

In the present invention, the organic solvent is an inert solvent that does not participate in the copolymerization reaction, and provides a dispersion medium for the copolymerization reaction. Preferably, the concentration of maleic anhydride in the organic solvent is from 5% to 25% by weight; preferably 10 wt% to 20 wt%. The organic solvent is preferably at least one of isoamyl acetate, butyl acetate, isopropyl acetate and ethyl acetate.

In the present invention, the copolymerization reaction conditions may be conditions that enable the copolymerization reaction of the carbon tetraene and the maleic anhydride in the mixed carbon four. Preferably, the copolymerization reaction temperature is 50-100 ℃, preferably 70-90 ℃; the copolymerization pressure is 0.2-2MPa, preferably 0.5-1 MPa; the copolymerization reaction time is 5-10 h.

In the invention, a certain amount of mixed C4 is introduced into a reaction kettle containing a certain amount of maleic anhydride, an initiator and an organic solvent to carry out copolymerization reaction under the conditions of nitrogen atmosphere and the copolymerization reaction, and then the reaction product is subjected to flash separation and centrifugal separation to obtain the mixed butene-maleic anhydride copolymerized microspheres. Wherein, the mixed C4, the maleic anhydride, the initiator and the organic solvent are used in the same amount as described above. The flash separation may be carried out in a flash separator at about 25 ℃ and 0 MPa. The centrifugation may be carried out at a rotation speed of about 4000rpm for about 20 min. The obtained microspheres can be further washed by hexane and filtered by a sand core to obtain a filter cake, and after the filter cake is dried in vacuum at about 90 ℃ for about 8 hours, the obtained product is the mixed butylene-maleic anhydride copolymerized microspheres with the particle size of 0.05-2 mu m, preferably 0.2-2 mu m, and the composition structure and the content of the mixed butylene-maleic anhydride copolymerized microspheres can be further analyzed and used for the high-melt-strength polypropylene.

Polypropylene

In the present invention, the polypropylene is preferably a polypropylene having a high melt strength. Preferably, the polypropylene is selected from homopolypropylenes; the melt flow rate of the polypropylene at 230 ℃ and under a 2.16kg load is 0.1 to 3g/10min, the molecular weight distribution Mw/Mn of the polypropylene is 5 to 20, and the dispersion index of the polypropylene is 5 to 16. Preferably, the poly (I) sThe density of the propylene is 0.895-0.905g/cm³。

In the present invention, the polypropylene may be obtained by itself or commercially, for example, homopolymeric high melt strength polypropylene may be prepared by the methods disclosed in CN102134291A and CN102134290A (the entire contents of CN102134291A and CN102134290A are incorporated herein by reference) or may be obtained from polypropylene under the brand name HMS 20Z.

Composite antioxidant

In the present invention, the complex antioxidant may include at least one selected from hindered phenol antioxidants, phosphite antioxidants, and thioester antioxidants. Specifically, the hindered phenol antioxidant may be monophenol, bisphenol, and polyphenol; the phosphite antioxidant comprises alkyl phosphite and aryl phosphite; the sulfofat antioxidant comprises a sulfofat antioxidant, a sulfophenol antioxidant and a sulfobisphenol antioxidant. The hindered phenol antioxidant, phosphite antioxidant and thioester antioxidant are known substances and are commercially available. For example, antioxidant 1010 (hindered phenol antioxidant), antioxidant 168 (phosphite antioxidant). Preferably, the composite antioxidant can also be added with calcium stearate to increase the antioxidant effect of the polypropylene. For example, the composite antioxidant is preferably composed of a mixture of the antioxidant 1010, the antioxidant 168 and calcium stearate in a weight ratio of 2:2: 1.

Foaming agent

In the present invention, the blowing agent may be used in an amount of preferably 1 to 10 parts by weight, more preferably 5 to 7 parts by weight. The blowing agent may be an organic chemical blowing agent, for example, one of azo type blowing agents, which may be preferably Azodicarbonamide (AC), Azodiisobutyronitrile (AIBN), barium azodicarboxylate (BaAC), and azodicarboxylate, nitroso type blowing agents, which may be preferably Dinitrosopentamethylenetetramine (DPT), N ' -dinitrosopentamethylenetetramine, N ' -dimethyl-N, N-dinitrosoterephthalamide (NTA), and trinitrotrimethylenetriamine, and hydrazide type blowing agents, which may be preferably 4,4' -oxybis-benzenesulfonylhydrazide (OBSH), Toluenesulfonylaminourea (TSSC), triphosphonyltriazine (CTHT), and 5-phenyltetrazole; more preferably Azodicarbonamide (AC). The blowing agent may also be an inorganic gaseous blowing agent, such as one or more of carbon dioxide, nitrogen, air and water. When carbon dioxide is selected as the blowing agent, the carbon dioxide is 1 to 10 parts by weight corresponding to 100 parts by weight of the high melt strength polypropylene.

Guanidine salt composite antibacterial agent

In the invention, the guanidine salt composite antibacterial agent can contain a guanidine salt polymer, a zinc salt and/or a copper salt, an anti-migration agent, nano-scale powder rubber and a dispersing agent.

Preferably, the zinc salt and/or the copper salt is 0.01 to 40 parts by weight, the anti-migration agent is 0.1 to 10 parts by weight, the nano-sized powder rubber is 0.5 to 100 parts by weight, and the dispersant is 0.1 to 10 parts by weight, relative to 100 parts by weight of the guanidine salt polymer. Preferably, the zinc salt and/or the copper salt, the anti-migration agent, the nano-scale powder rubber and the dispersant are 5 to 25 parts by weight, 0.5 to 5 parts by weight, 4.5 to 50 parts by weight and 0.5 to 5 parts by weight, respectively, relative to 100 parts by weight of the guanidine salt polymer.

In the present invention, the guanidine salt polymer may be selected from at least one of an inorganic acid salt and/or an organic acid salt of polyhexamethylene (bis) guanidine, and polyoxyethylene guanidine; preferably at least one selected from the group consisting of polyhexamethylene (bis) guanidine hydrochloride, polyhexamethylene (bis) guanidine phosphate, polyhexamethylene (bis) guanidine acetate, polyhexamethylene (bis) guanidine propionate, polyhexamethylene (bis) guanidine stearate, polyhexamethylene (bis) guanidine laurate, polyhexamethylene (bis) guanidine benzoate and polyhexamethylene (bis) guanidine sulfonate; further preferred is polyhexamethylene (bis) guanidine hydrochloride and/or polyhexamethylene (bis) guanidine propionate.

In the invention, the zinc salt and/or the copper salt can be inorganic zinc salt and/or inorganic copper salt; preferably at least one selected from the group consisting of zinc sulfate, zinc nitrate, zinc chloride, copper sulfate, copper nitrate and copper chloride; further preferably zinc sulfate and/or copper sulfate.

In the present invention, the anti-migration agent may be a blocked polyisocyanate, preferably at least one selected from the group consisting of phenol blocked polyisocyanate, caprolactam blocked polyisocyanate, and butanone oxime blocked polyisocyanate.

In the invention, the nano-scale powder rubber can be at least one of fully vulcanized styrene-butadiene rubber, fully vulcanized carboxyl styrene-butadiene rubber, fully vulcanized nitrile-butadiene rubber, fully vulcanized carboxyl nitrile-butadiene rubber, fully vulcanized acrylate rubber, fully vulcanized ethylene vinyl acetate rubber, fully vulcanized silicon rubber and fully vulcanized butadiene-styrene-pyridine rubber which are subjected to radiation crosslinking; preferably fully vulcanized styrene-butadiene rubber and/or fully vulcanized silicone rubber.

In the invention, the content control of the nano-powder rubber can help to reduce the moisture absorption of the guanidine salt composite antibacterial agent during storage, and increase the operability and the use timeliness in practical application.

In the invention, the dispersant can be nano-scale inorganic powder, preferably at least one selected from nano-scale calcium carbonate, silicon dioxide, montmorillonite, zinc oxide, talcum powder, titanium dioxide, carbon nano tube, graphene, carbon fiber, boron nitride, zirconium dioxide, wollastonite and zeolite; further preferred is nanoscale calcium carbonate and/or nanoscale fumed silica.

In the invention, the preparation method of the guanidine salt composite antibacterial agent comprises the following steps:

a. contacting an aqueous solution of a guanidinium polymer with an aqueous solution of a zinc salt and/or a copper salt to form a transparent liquid mixture;

b. mixing the liquid mixture obtained in the step a with a latex solution after radiation crosslinking, and then adding an anti-migration agent to obtain a mixture;

c. and c, carrying out spray drying on the mixture obtained in the step b to obtain solid powder, and then mixing the solid powder with a dispersing agent to obtain the guanidine salt composite antibacterial agent.

Wherein the latex can be determined according to the type of the finally required powdered rubber, and the latex can be at least one of styrene-butadiene latex, carboxylic styrene-butadiene latex, butyronitrile latex, carboxylic butyronitrile latex, acrylate latex, ethylene vinyl acetate latex, silicon rubber latex and styrene-butadiene-pyridine latex; preferably styrene-butadiene latex and/or silicone rubber latex.

A large number of experiments show that the guanidine salt composite antibacterial agent can be prepared more smoothly when the concentrations of a guanidine salt polymer aqueous solution, a zinc salt and/or copper salt aqueous solution and a latex solution are in a certain range. The concentrations of the guanidine salt polymer aqueous solution, the zinc salt and/or copper salt aqueous solution and the latex emulsion are not high enough, otherwise, the uniform stirring is not facilitated, the coagulation phenomenon can occur, and the subsequent spray drying operation can not be carried out; the concentration should not be too low, otherwise, the production efficiency will be low, and water and energy resources will be wasted. Specifically, the mass concentration of the aqueous solution of the guanidinium polymer may be 10% to 40%, preferably 15% to 25%. The mass concentration of the aqueous solution of the zinc salt and/or the copper salt can be 15-30%, and preferably 20-25%. The mass concentration of the latex solution is 30-40%.

Wherein the spray drying may be carried out in a spray dryer. The mixing of the solid powder and the dispersing agent can be carried out in a high-speed stirrer, and the guanidine salt composite antibacterial agent of the invention is obtained after high-speed stirring and dispersing.

The aqueous guanidinium polymer solution may be obtained by dissolving a guanidinium polymer solid in water or may be obtained commercially directly. Preferably, the weight ratio of the guanidine salt polymer in the guanidine salt polymer aqueous solution, the zinc salt and/or copper salt in the zinc salt and/or copper salt aqueous solution, the solid solution in the latex solution, the anti-migration agent and the dispersant is 100: 0.01-40: 0.5-100: 0.1-10: 0.1 to 10; the preferable weight ratio is 100: 5-25: 4.5-50: 0.5-5: 0.5-5.

Mildew preventive

In the present invention, the mildewcide may be various mildewcides conventionally used for thermoplastic resin compositions in the art, preferably one selected from the group consisting of pyrithione compounds, isothiazolinone compounds, 10 ' -oxodiphenol Oxazine (OBPA), 3-iodo-2-propynyl butyl carbamate (IPBC), 2,4,4' -trichloro-2 ' -hydroxydiphenyl ether (triclosan) and 2- (thiazol-4-yl) benzimidazole (thiabendazole), and is preferably a pyrithione compound.

The pyrithione compound is preferably zinc pyrithione, copper pyrithione, or dipyrithione.

The isothiazolinone compound is preferably at least one of 2-methyl-1-isothiazolin-3-one (MIT), 5-chloro-2-methyl-1-isothiazolin-3-one (CMIT), 2-n-octyl-4-isothiazolin-3-One (OIT), 4, 5-dichloro-2-n-octyl-3-isothiazolinone (DCOIT), 1, 2-benzisothiazolin-3-one (BIT), 4-methyl-1, 2-benzisothiazolin-3-one (MBIT), 4-n-butyl-1, 2-benzisothiazolin-3-one (BBIT).

In the present invention, it is preferable that the mildewcide is zinc pyrithione and/or DCOIT.

Other auxiliaries

In the invention, the composition can also contain other auxiliary agents, and the performance of the polypropylene is not affected. The auxiliary may be at least one selected from a slipping agent, an antistatic agent, a lubricant and a plasticizer. Preferably, the high melt strength polypropylene further comprises glycerol monostearate in an amount of 1 to 10% by weight of the copolymer microspheres. Can help to improve the dispersibility of the mixed butylene-maleic anhydride copolymerized microspheres in the polypropylene.

In the preparation method provided by the invention, glycerol monostearate can be added into the mixture in the step (1), and the addition amount is 1-10 wt% of the mixed butylene-maleic anhydride copolymer microspheres. Other adjuvants may also be added, as described above. The mixing may be performed at normal temperature. The temperature of the extrusion granulation in the step (1) is 180-230 ℃. The polypropylene added in step (1) of the above preparation method is preferably homopolypropylene. The high melt strength polypropylene obtained in the step (1) can be subjected to mechanical property, thermal deformation and oxidation induction period tests.

According to the invention, the mixed butene-maleic anhydride copolymer microspheres obtained by processing the mixed C4 are utilized, so that the composition structure of the obtained high-melt-strength polypropylene contains maleic anhydride structural units, and the high-melt-strength polypropylene has obviously improved mechanical properties, thermal aging resistance, thermal deformation temperature and oxidation induction period. The method provided by the invention is simple and operable, is easy for industrial popularization, can effectively reduce waste of mixed carbon four resources, and has good economic and social benefits.

The step (2) of the invention can be carried out at normal temperature when the material mixing is carried out. The temperature of the extrusion foaming molding can be 150-280 ℃, and preferably 160-180 ℃. Different die molds are arranged on the extruder for extrusion foaming molding, so that a polypropylene molding foaming finished product to be molded can be obtained, and the temperature of the die molds can be controlled at 160-180 ℃. The neck ring mold can be a flat neck ring mold, a T-shaped neck ring mold, a round hole neck ring mold or a circular ring neck ring mold according to actual needs, and the polypropylene foaming plate with the corresponding structure is obtained.

If the foaming agent is an inorganic gas foaming agent, the inorganic gas foaming agent can be added by using a special foaming extruder with a gas injection device. At the moment, the premix in the step (2) does not contain a foaming agent, and an inorganic gas foaming agent is added during extrusion foaming molding.

Preferably, the foamed polypropylene sheet obtained by the invention can have a density of 0.2-0.41g/cm³(determined by GB/T1033.1-2008), tensile strength is 4.1-5.5MPa, bending strength is 3.7-4.8MPa, and impact strength of a simple beam notch (23 ℃) is 1.5-2.7KJ/m²And the oxidative induction period OIT is 31.2-34.9 min. Compared with the polypropylene foaming material obtained by using the prior art such as chemical or physical crosslinking, the polypropylene foaming material obtained by the invention does not contain a crosslinking structure, the product is environment-friendly and recyclable, the influence on the environment is reduced, and the economic requirement of the cycle is compounded.

The polypropylene foamed sheet prepared by the method has the advantages of compact pores, uniform pore size distribution, smooth surface, high thermal-oxidative aging resistance and the like, and can be applied to occasions with high requirements on thermal-oxidative aging resistance and light weight of plastic products, such as automobile parts, food and electronic packaging, architectural decoration and the like.

The present invention will be described in detail below by way of examples.

In the following examples and comparative examples, the relevant data were obtained according to the following test methods:

melt flow rate MI: the measurement is carried out according to the method specified in GB/T3682-2000, wherein the test temperature is 230 ℃, and the load is 2.16 kg;

density of polypropylene: measuring by a density gradient column method according to a method specified in GB/T1033.2-2010;

the density of the foamed sheet is measured by GB/T1033.1-2008;

the tensile properties are tested according to ISO-527 standard;

the bending property is tested according to the ISO-178 standard;

the impact performance is tested according to the standard of a simply supported beam notch ISO-179;

testing the heat distortion temperature according to ISO-75 standard;

the oxidation induction period is tested according to ISO11357-6, the test temperature is 200 ℃;

and (3) antibacterial testing: the detection is carried out according to QB/T2591-2003A 'antibacterial property test method and antibacterial effect of antibacterial plastics': escherichia coli (Escherichia coli) ATCC 25922, Staphylococcus aureus (Staphylococcus aureus) ATCC 6538.

The sample piece is soaked in hot water at 50 ℃ for 16h before the antibacterial test. The test procedure was as follows: and (3) sterilizing a sample to be detected by using 75% ethanol, drying the sample, and diluting the strain into a bacterial suspension with a proper concentration by using sterile water for later use. 0.2mL of the bacterial suspension was dropped on the surface of the sample, and a polypropylene film (4.0 cm. times.4.0 cm) having a thickness of 0.1mm was coated thereon to form a uniform liquid film between the sample and the film. Culturing at 37 deg.C under relative humidity of 90% for 18-24 h. The bacterial liquid is washed by sterile water, diluted to a proper concentration gradient, and 0.1mL of the bacterial liquid is uniformly coated on the prepared sterile agar culture medium. Culturing at 37 deg.C for 18-24h, and observing the result. The negative control was replaced with a sterile plate and the other operations were identical.

Mildew resistance test, according to ASTM G21-96: the growth of the mold was observed for 28 days:

level 0: no growth, i.e. no growth observed under microscope (magnification 50);

level 1: trace growth, i.e., growth visible to the naked eye, but growth coverage area is less than 10%;

and 2, stage: the growth coverage area is not less than 10%.

The bacteria for detection are shown in Table 5:

TABLE 5

Serial number	Name (R)	Bacterial number
			1	Aspergillus niger (Aspergillus niger)	AS3.4463
2	Aspergillus terreus (Aspergillus terreus)	AS3.3935
			3	Aureobasidium Pullulans (Aureobasidium Pullulans) u	AS3.3984
4	Paecilomyces Varioti (Paecilomyces Varioti)	AS3.4253
			5	Penicillium funiculosum (Penicillium funiculosum)	AS3.3872
6	Ball shell (Chaetomium globosum)	AS3.4254

The mixed C-C A comprises (by weight percent) 1, 2-butadiene, 8.92%; 1, 3-butadiene, 14.14%; 1-butene, 8.38%; trans-2-butene, 5.84%; cis-2-butene, 31.7%; vinyl acetylene, 10.99%; isobutane, 1.3%; isobutene, 12.78%; n-butane 2.58%, others, 3.37%.

The mixed C-B comprises the following components in percentage by weight: 1, 3-butadiene, 0.06%; trans-2-butene, 12.67%; isobutane, 37.09%; 19.48 percent of isobutene; cis-2-butene, 27.79%; 1-butene, 1.02%; others, 1.89%.

The mixed C-C comprises the following components in percentage by weight: trans-2-butene, 40.83%; cis-2-butene, 18.18%; 24.29 percent of n-butane; 1-butene, 9.52%; isobutene, 2.78%; others, 4.4%.

Homo-polypropylene: polypropylene of HMS20Z, chinese petrochemical (melt flow rate at 230 ℃ and 2.16kg load of 2.2g/10min, molecular weight distribution Mw/Mn of 8.8, dispersion index PI of 7.9, density of 0.902g/cm³)。

polypropylene-DPP: china petrochemical company T03 brand (melt flow rate at 230 ℃ and 2.16kg load of 1.9g/10min, molecular weight distribution Mw/Mn of 4, dispersion index PI of 3.6, density of 0.901g/cm³)。

Preparation example 1

Polypropylene HMSPP101 and HMSPP102 were prepared according to CN102134290A, examples 1 and 2, respectively.

HMSPP 101: the melt flow rate at 230 ℃ and 2.16kg load was 1.6g/10min, the molecular weight distribution Mw/Mn was 11.2 and the dispersion index PI was 15.0. The density is 0.895-0.905g/cm³Within the range.

HMSPP 102: the melt flow rate at 230 ℃ and 2.16kg load was 2.7g/10min, the molecular weight distribution Mw/Mn was 11.1 and the dispersion index PI was 9.3. The density is 0.895-0.905g/cm³Within the range.

Preparation example 2

Preparation of mixed butylene-maleic anhydride copolymer microspheres

Mixed butene-maleic anhydride copolymerized microsphere powder a:

under the protection of nitrogen, 15kg of mixed C-IV A is introduced into a 200L reaction kettle containing organic reaction liquid of 22kg of maleic anhydride, 2.6kg of azodiisobutyronitrile and 100L of isoamyl acetate for copolymerization reaction, the copolymerization reaction pressure is 0.98MPa, the copolymerization reaction temperature is 75 ℃, and the copolymerization reaction time is 6 h;

and introducing the copolymerization reaction product into a flash separator for gas-liquid separation at the temperature of 25 ℃ and under the pressure of 0MPa, continuously carrying out liquid-solid separation on the obtained liquid-solid mixture in a centrifugal separator at the rpm of 4000 for 20min to obtain a solid product, washing with hexane, and carrying out vacuum drying on a filter cake obtained by suction filtration through a sand core funnel for 8h at the temperature of 90 ℃ to obtain mixed butene-maleic anhydride copolymerized microsphere powder A. The copolymer powder was subjected to a test in which the content of maleic anhydride structural units was 32 mol%; the average particle diameter was 2 μm.

Mixed butene-maleic anhydride copolymerized microsphere powder B:

under the protection of nitrogen, 15.5kg of mixed C-IV B is introduced into a 200L reaction kettle containing 21.2kg of maleic anhydride, 3.9kg of dibenzoyl peroxide and 100L of isoamyl acetate to carry out copolymerization reaction, wherein the copolymerization reaction pressure is 1.05MPa, the copolymerization reaction temperature is 85 ℃, and the copolymerization reaction time is 6 h;

and introducing the copolymerization reaction product into a flash separator for gas-liquid separation at 30 ℃ and 0MPa, continuously performing liquid-solid separation on the obtained liquid-solid mixture in a centrifugal separator at 4000rpm for 20min to obtain a solid product, washing with hexane, and performing vacuum drying on a filter cake obtained by suction filtration of a sand core funnel at 90 ℃ for 8h to obtain mixed butene-maleic anhydride copolymerized microsphere powder B. The copolymer powder was tested, wherein the content of maleic anhydride structural units was 48 mol%; the average particle diameter was 5 μm.

Obtaining mixed butene-maleic anhydride copolymerized microsphere powder C:

introducing 15.6kg of mixed C-C into a 200L reaction kettle containing 19.8kg of maleic anhydride, 4.0kg of dibenzoyl peroxide and 100L of isoamyl acetate to carry out copolymerization reaction, wherein the copolymerization reaction pressure is 1.3MPa, the copolymerization reaction temperature is 80.5 ℃, and the copolymerization reaction time is 10 h;

and introducing the copolymerization reaction product into a flash separator for gas-liquid separation at 30 ℃ and 0MPa, continuously performing liquid-solid separation on the obtained liquid-solid mixture in a centrifugal separator at 8000rpm for 20min to obtain a solid product, washing with hexane, and performing vacuum drying on a filter cake obtained by suction filtration of a sand core funnel at 90 ℃ for 8h to obtain mixed butene-maleic anhydride copolymerized microsphere powder C. The copolymer powder was subjected to a test in which the content of maleic anhydride structural units was 55 mol%; the average particle diameter was 0.1. mu.m.

Preparation example 3

And preparing the guanidine salt composite antibacterial agent.

1# of composite antibacterial agent:a. 1000.0g of polyhexamethylene guanidine hydrochloride (practice Co., Ltd., Shanghai) was dissolved in water to prepare an aqueous solution having a mass concentration of 20%; 50.0g of zinc sulfate is prepared into an aqueous solution with the mass concentration of 25 percent, and 125.0g of styrene-butadiene latex solution is directly used after radiation crosslinking, and the concentration is 40 percent. b. Will be preparedAdding the guanidine salt polymer aqueous solution into a container containing the zinc-containing aqueous solution, stirring while adding until the guanidine salt polymer aqueous solution and the zinc-containing aqueous solution are uniformly mixed to form a transparent liquid mixture. c. Adding the liquid mixture of step b to the latex solution while stirring until uniformly mixed, and then adding 5.0g of an anti-migration agent (Coresi wound) to the mixture

2794 XP). d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; transferring the obtained solid powder to a high-speed stirrer, adding 5.0g of fumed silica serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent 1 #.

Composite antibacterial agent 2 #:a. 1000.0g of polyhexamethylene guanidine propionate (Utility Co., Ltd., Shanghai mountain) was dissolved in water to prepare an aqueous solution having a mass concentration of 40%; 100.0g of zinc acetate is prepared into an aqueous solution with the mass concentration of 15 percent, and 150.0g of butyronitrile latex solution is directly used after radiation crosslinking, and the concentration is 30 percent. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, stirring while adding until the guanidine salt polymer aqueous solution and the zinc-containing aqueous solution are uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 5.0g of an anti-migration agent (Colesine) was added to the mixture

2794 XP). d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; transferring the obtained solid powder to a high-speed stirrer, adding 15.0g of nano calcium carbonate as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent No. 2.

Composite antibacterial agent 3 #:a. 1000.0g of polyhexamethylene biguanide hydrochloride (practice Co., Ltd., Shanghai mountain) was dissolved in water to prepare an aqueous solution having a mass concentration of 10%; 200.0g of zinc nitrate is prepared into 30 percent aqueous solution, 125.0g of silicon rubber latex solution is directly used for radiation crosslinkingFor use, the concentration was 40%. b. Adding the prepared guanidine salt polymer aqueous solution into a container containing a zinc-containing aqueous solution, stirring while adding until the guanidine salt polymer aqueous solution and the zinc-containing aqueous solution are uniformly mixed to form a transparent liquid mixture. c. And c, adding the liquid mixture obtained in the step b into the latex solution, and stirring while adding until the mixture is uniformly mixed. Then, 5.0g of an anti-migration agent (Colesine) was added to the mixture

2794 XP). d. C, drying the mixture obtained in the step c by using a spray dryer to obtain solid powder; and transferring the obtained solid powder into a high-speed stirrer, adding 30.0g of talcum powder serving as a dispersing agent, and mixing and dispersing at a high speed to obtain the guanidine salt composite antibacterial agent # 3.

Examples 1 to 14

Preparing the high melt strength polypropylene.

Mixing the mixed butene-maleic anhydride copolymer microspheres, a composite antioxidant (an antioxidant 1010: an antioxidant 168: calcium stearate 2:2:1 (weight ratio)), and glycerol monostearate (Dada, ATMER 129V) according to a ratio shown in Table 1, and stirring by using a dry powder machine to obtain a uniformly mixed mixture;

adding the mixture and polypropylene (HMSPP101, HMSPP102, HMS20Z or DPP) into a high-speed mixer according to the mixture ratio in Table 1, and mixing to obtain a blend; the blend was then fed into a twin-screw extruder and extruded and pelletized at 195-210 ℃ to obtain high melt strength polypropylene (designated as HPP) and test specimens were prepared and the heat distortion temperature and oxidation induction period were measured, the results are shown in Table 2.

Comparative examples 1 to 6

Mixing butene-maleic anhydride copolymer microspheres and a composite antioxidant (antioxidant 1010: antioxidant 168: calcium stearate 2:2:1 (weight ratio)) according to the mixture ratio shown in Table 1, and stirring the mixture by using a dry powder machine to obtain a uniformly mixed mixture;

adding the mixture and polypropylene (HMSPP101, HMSPP102 or HMS20Z) into a high-speed mixer for mixing to obtain a blend; the blend was then fed into a twin-screw extruder and extruded at 195-210 ℃ for pelletization to give polypropylene (CPP) and test specimens were prepared for measurement of the heat distortion temperature and the oxidation induction period, the results of which are shown in Table 2.

TABLE 1

Note: the dosage is weight portion.

TABLE 2

Numbering	Heat distortion temperature (0.45MPa) (. degree.C.)	Oxidative induction period OIT (min)
			Example 1	95.6	36.5
Example 2	96.1	36.8
			Example 3	97.2	37.4
Example 4	94.5	36.6
			Comparative example 1	89.5	28.5
Comparative example 2	84.1(HMSPP101 pure resin)	9.9
			Example 5	92.9	35.6
Example 6	93.7	35.2
			Example 7	94.9	34.5
Example 8	95.6	33.6
			Comparative example 3	88.1	25.3
Comparative example 4	82.6(HMS20Z pure resin)	9.7
			Example 9	10.2	33.5
Example 10	68.6	31.6
			Example 11	90.5	33.5
Example 12	91.6	34.1
			Example 13	92.1	35.2
Example 14	91.1	34.3
			Comparative example 5	85.6	19.6
Comparative example 6	79.5	9.1

As can be seen from the data in tables 1 and 2, the heat distortion temperature of the polypropylene composition increases and the oxidation induction period is prolonged with the addition of the copolymerized microspheres. However, when the amount of the copolymerized microspheres exceeds 10 parts by weight, the heat distortion temperature and the oxidation induction period are similar to those of the virgin polypropylene. Therefore, the heat resistance and the thermo-oxidative aging resistance of the polypropylene base resin need to be effectively improved by controlling the addition ratio of the good copolymerization microspheres.

Examples 15 to 28

Preparing the foamed polypropylene.

Mixing polypropylene (HPP-1 to HPP-14), a composite antibacterial agent (prepared in preparation example 3), a mildew preventive and a foaming agent according to the mixture ratio in a table 3 to obtain a premix; and then the premix is foamed and extruded to form a foamed plate.

The results of the property measurements of the foamed sheet obtained are shown in Table 4.

Comparative examples 7 to 12

Mixing polypropylene (CPP-1 to CPP-6), a composite antibacterial agent (prepared in preparation example 3), a mildew preventive and a foaming agent according to the mixture ratio in Table 3 to obtain a premix; and then the premix is foamed and extruded to form a foamed plate.

Comparative example 13

Mixing polypropylene (HPP-1), polyhexamethylene biguanide hydrochloride (antibacterial agent) and a foaming agent to obtain a premix according to the mixture ratio in the table 3; and then the premix is foamed and extruded to form a foamed plate.

TABLE 3

Note: the dosage is weight portion.

The results of SEM image observation of the expanded polypropylene obtained in each of examples 15 and 23 are shown in FIGS. 1 and 2. It can be seen that example 15 uses the polypropylene numbered HMSPP101, extrusion foamed polypropylene, and SEM images of the cross-section (shown in figure 1) show good cell morphology without cell rupture. Whereas example 23 uses DPP-numbered polypropylene, the parameters are not within the ranges defined by the technical solution of the present invention, and the SEM image (shown in fig. 2) of the cross section of the obtained expanded polypropylene shows that the cells collapse, the cell morphology is poor, corresponding to lower mechanical properties.

In the examples and comparative examples provided by the present invention, examples 1 to 4 and comparative examples 1 to 2 using HMSPP101 were grouped according to the polypropylene numbers used, and the corresponding foamed products were examples 15 to 18 and comparative examples 7 and 9; and wherein, example 18 corresponds to example 15 less glycerol monostearate. Examples 5-8 and comparative examples 3-4 using HMS20Z are one set, corresponding to foamed products of examples 19-22 and comparative examples 8, 10; and wherein example 22 corresponds to example 19 with less glyceryl monostearate. Examples 11-14 and degree ratios 5-6 using HMSPP102 are in one group, corresponding to foamed products being examples 25-28 and comparative examples 11, 12; and wherein, example 28 corresponds to example 25 less glycerol monostearate. The polypropylene used in examples 9 to 10 did not have the parameters of the polypropylene defined in the present invention, and the other compositions corresponded to examples 1, 5 and 11, but example 10 contained less glyceryl monostearate than example 9. Comparative examples 1,3 and 5 correspond to examples 1, 5 and 11, respectively, and the amount of the mixed butene-maleic anhydride copolymer microspheres is outside the range defined by the present invention and is free of glycerol monostearate; comparative examples 2,4, and 6 are also comparative examples 1,3, and 5, in which no mixed butene-maleic anhydride copolymer microspheres were added. The composition of comparative example 13 was altered from that of example 15 in that polyhexamethylene biguanide hydrochloride was used as the antimicrobial agent and no mildewcide was used.

As can be seen from the examples, comparative examples and data in tables 1 to 4 of the present invention, the foamed polypropylene composition provided by the present invention comprises mixed butene-maleic anhydride copolymer microspheres as a cell nucleating agent, and a foamed sheet which can be prepared by extrusion foaming in combination with other components can contain maleic anhydride structural units, and the sheet has the effects of dense and uniform cells, no fracture, and better thermal-oxidative aging resistance. In addition, the invention can use organic chemical foaming agent or inorganic gas foaming agent to foam and form. The foamed polypropylene plate provided by the invention has antibacterial and mildewproof properties.

The foamed polypropylene composition provided by the invention also selects specially limited homo-polypropylene such as HMS20Z, HMSPP101 and HMSPP102, and can be mixed with the mixed butylene-maleic anhydride copolymer microspheres to improve the mechanical property of the prepared foamed polypropylene board. Furthermore, the mechanical properties of the foamed polypropylene sheet obtained by using the mixed butene-maleic anhydride copolymer microspheres can be improved compared with those of the foamed polypropylene sheet obtained by using inorganic nucleating agents (such as talcum powder and silicon dioxide). for example, the inorganic cell nucleating agents used in comparative examples 9, 10 and 12 have poorer mechanical properties compared with examples 15, 19 and 25 which are compositions corresponding to the present invention and use the mixed butene-maleic anhydride copolymer microspheres as cell nucleating agents.

In addition, the foaming polypropylene provided by the invention is not chemically or physically crosslinked, but has good mechanical and thermal oxidation resistance, is more widely applied, is environment-friendly, can be recycled and meets the economic requirement of recycling.

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 foamed polypropylene composition comprising: 100 parts of high melt strength polypropylene, 0.05-2 parts of guanidine salt composite antibacterial agent, 0.05-5 parts of mildew preventive and 1-15 parts of foaming agent; wherein the high melt strength polypropylene comprises the following components: 100 parts of polypropylene, 0.1-0.3 part of composite antioxidant and 0.25-10 parts of mixed butylene-maleic anhydride copolymer microspheres; wherein the particle size of the copolymer microsphere is 0.1-10 μm.

2. The composition of claim 1, wherein the mixed butene-maleic anhydride copolymerized microspheres have a maleic anhydride structural unit content of 30 to 70 mol%.

3. The composition of claim 2, wherein the mixed butene-maleic anhydride copolymerized microspheres have a maleic anhydride structural unit content of 48 to 55 mol%.

4. The composition of any of claims 1-3, wherein the mixed butene-maleic anhydride copolymerized microspheres are a copolymer of maleic anhydride and a carbon tetraene prepared by copolymerization of mixed carbon four and maleic anhydride in the presence of nitrogen, an initiator, and an organic solvent.

5. The composition of claim 4, wherein the mixed butene-maleic anhydride copolymer microspheres are copolymer microspheres of maleic anhydride and n-butene, isobutylene.

6. The composition of claim 4, wherein the weight ratio of mixed C4 to maleic anhydride is (0.2-3): 1;

and/or the initiator is used in an amount of 0.05 to 20 mol% based on the maleic anhydride.

7. The composition of claim 6, wherein the weight ratio of mixed C4 to maleic anhydride is (0.8-3): 1.

8. the composition of claim 5, wherein the weight ratio of mixed C4 to maleic anhydride is (0.2-3): 1;

9. The composition of claim 8, wherein the weight ratio of mixed carbon four to maleic anhydride is (0.8-3): 1.

10. the composition of claim 4, wherein the concentration of maleic anhydride in the organic solvent is 5-25% by weight.

11. The composition of claim 10, wherein the concentration of maleic anhydride in the organic solvent is 10-20% by weight.

12. The composition of claim 5, wherein the concentration of maleic anhydride in the organic solvent is 5-25% by weight.

13. The composition of claim 12, wherein the concentration of maleic anhydride in the organic solvent is 10-20% by weight.

14. The composition of claim 4, wherein the copolymerization temperature is 50-100 ℃; the copolymerization pressure is 0.2-2 MPa; the copolymerization reaction time is 5-10 h.

15. The composition of claim 14, wherein the copolymerization temperature is 70-90 ℃; the copolymerization pressure is 0.5-1 MPa.

16. The composition of any one of claims 5-13, wherein the copolymerization temperature is 50-100 ℃; the copolymerization pressure is 0.2-2 MPa; the copolymerization reaction time is 5-10 h.

17. The composition of claim 16, wherein the copolymerization temperature is 70-90 ℃; the copolymerization pressure is 0.5-1 MPa.

18. The composition according to any one of claims 1-3, 5-15, 17, wherein the polypropylene is selected from homopolypropylene; the melt flow rate of the polypropylene at 230 ℃ and under a load of 2.16kg is 0.1 to 3g/10min, the molecular weight distribution M of the polypropylene_w/M_nIs 5-20, and the polypropylene has a dispersion index of 5-16.

19. According toThe composition of claim 4, wherein the polypropylene is selected from the group consisting of homopolypropylene; the melt flow rate of the polypropylene at 230 ℃ and under a load of 2.16kg is 0.1 to 3g/10min, the molecular weight distribution M of the polypropylene_w/M_nIs 5-20, and the polypropylene has a dispersion index of 5-16.

20. The composition of claim 16, wherein the polypropylene is selected from the group consisting of homopolypropylene; the melt flow rate of the polypropylene at 230 ℃ and under a load of 2.16kg is 0.1 to 3g/10min, the molecular weight distribution M of the polypropylene_w/M_nIs 5-20, and the polypropylene has a dispersion index of 5-16.

21. The composition of claim 1 wherein the high melt strength polypropylene further comprises glycerol monostearate in an amount of 1 to 10 wt% of the copolymer microspheres.

22. A preparation method of a foamed polypropylene plate comprises the following steps:

and carrying out extrusion foaming molding on the premix to obtain the foamed polypropylene plate.

23. A foamed polypropylene sheet produced by the production method as claimed in claim 22.