Polypropylene foamed beads and molded polypropylene foamed beads, their preparation methods and applications

Abstract

This invention relates to the field of polymer materials technology, and discloses a polypropylene foamed bead, a molded polypropylene foamed bead, its preparation method, and its application. The polypropylene foamed beads are obtained by foaming a foaming composition containing polypropylene microparticles; the average particle size of the polypropylene microparticles is ≤1 mm, the aspect ratio of the polypropylene microparticles is ≤1.2, the ash content is ≤400 ppm, and the bulk density is >0.35 g / cm³. 3 The polypropylene foam beads have a particle size of less than 1 mm, a bulk ratio to apparent size ratio of ≤1.6, and a closed-cell rate of ≥99%. This significantly reduces energy consumption during foam bead molding, and the foam bead molded bodies prepared from these beads exhibit superior appearance, mechanical properties, and thermal insulation properties. The shrinkage rate of the polypropylene foam bead molded bodies is less than 1.5%. This is particularly advantageous for preparing thin-walled or complex-shaped EPP molded products.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polypropylene foamed bead and a molded polypropylene foamed bead, as well as their preparation method and application. Background Technology

[0002] Polypropylene foam materials possess numerous advantages, including lightweight, high strength, heat and corrosion resistance, thermal insulation, shock absorption, sound absorption, reusability, adjustable closed-cell ratio for various applications, and environmentally friendly production processes and raw materials. The greatest advantage of autoclaved polypropylene beads (EPP beads) lies in their malleability. The uniform size and stable expansion ratio of EPP beads make them ideal for molding, enabling the production of products with complex geometries and high dimensional accuracy, making them suitable for the high-end market.

[0003] For EPP beads, in-mold secondary molding performance is crucial. This requires selecting polypropylene microparticles with regular shapes (ideally approximately spherical) and small particle sizes as the foaming material. Foamed beads prepared from relatively regular spherical microparticles are also approximately spherical, facilitating close packing during molding and reducing the formation of large pores. During molding, high-temperature steam (approximately 0.2MPa-0.4MPa pressure) is injected into the mold cavity, softening and melting the bead skin while simultaneously penetrating the interior of the bead and being compressed into a liquid state. Upon depressurization, the liquid water inside the cells vaporizes and expands along with the internal air, causing the contacting bead surfaces to adhere to each other. After cooling and solidification, the bead surfaces solidify, forming an effective bond between them. The bead molding process within the mold cavity is as follows: Figure 1 As shown, a represents the initial state, b represents the intermediate state, and c represents the molded product. At the same expansion ratio, smaller PP microparticles result in smaller foamed beads, which facilitates the transport of EPP beads in the process piping of the molding equipment, reduces clogging, and allows for tighter packing within the mold cavity. This leads to better adhesion between the beads during molding, resulting in superior mechanical and thermal insulation properties of the finished product. Furthermore, smaller particle size is advantageous for preparing thin-walled, complex-structured products, and also improves the surface finish of the finished product.

[0004] Currently, EPP manufacturers mainly use traditional methods such as strand granulation and underwater pelletizing to prepare polypropylene microparticles. The technical characteristics of strand granulation are well-known in the industry and will not be described in detail here. Its advantages are low equipment investment, ease of operation and maintenance, simple process conditions, and low energy consumption. However, its disadvantages are that it is difficult to control the particle size and aspect ratio of the microparticles. Typically, the particle size is above 1 mm, and the aspect ratio is around 2-3.

[0005] The underwater pelletizing system mainly consists of a gear pump, connecting components, an underwater pelletizer, a process water system, and a particle dryer. After the PP melt is melted in the screw heating section, it is pressurized at the gear pump (positive displacement pump), filtered, and quantitatively delivered to the pelletizer. Under thrust, the melt passes through the template holes to form a melt strip, which enters the water-filled pelletizing chamber. Rapidly rotating blades immediately cut the melt strip into pellets. Due to the large temperature difference between the melt and water, the granulated melt solidifies immediately, forming the spherical shape characteristic of underwater pelletizing (sphericity depends on the product's viscosity). A glass window allows observation of the pellets and water mixture leaving the pelletizing chamber. Particles suspended in the process water flow out of the pelletizing chamber and are separated from the process water in a centrifugal dryer. The process water is filtered, adjusted to the process temperature, and then pumped back into the pelletizing chamber. The microparticles are carried to the top by high-speed rotating blades and exit from the pelletizing outlet, where they are dried by the airflow of a blower. By adjusting the template orifice size (typically between 0.4-1mm), uniform and regular granules with a near-spherical appearance can be prepared, better meeting the requirements for foaming PP microparticles. However, underwater pelletizing systems are expensive, complex to operate and maintain, and typically operate at temperatures above 230℃, resulting in high energy and water consumption. Furthermore, the template orifice diameter cannot be too small, otherwise the extrusion pressure will increase dramatically, posing safety hazards; additionally, the melt expansion effect will cause the diameter of the extruded melt stream to exceed the orifice diameter, making it still difficult to control the particle size below 0.5mm.

[0006] The polypropylene autoclaved foam beads prepared by the above two processes usually have a particle size of more than 2 mm. Therefore, when they are stacked, the internal voids are very large, and the ratio between the bulk density and the apparent density is usually more than 1.8.

[0007] There is an urgent need to provide a polypropylene foam bead with a small particle size and a small ratio of bulk density to apparent density. Summary of the Invention

[0008] To address the shortcomings of the prior art, the present invention aims to provide polypropylene foam beads and polypropylene foam bead molded bodies, as well as their preparation methods and applications. The polypropylene foam beads are obtained by foaming a foaming composition containing polypropylene microparticles. The particle size of the polypropylene foam beads is less than 1 mm, and can be controlled to be less than 0.1 mm, thereby significantly reducing the energy consumption during foam bead molding. Furthermore, the foam bead molded bodies prepared from these beads have superior appearance, mechanical properties, and thermal insulation properties, and are particularly advantageous for preparing thin-walled or complex-shaped EPP molded body products.

[0009] To achieve the above objectives, the present invention provides polypropylene foamed beads, characterized in that the polypropylene foamed beads are obtained by foaming a foaming composition containing polypropylene microparticles.

[0010] The polypropylene microparticles have an average particle size of ≤1mm, an aspect ratio of ≤1.2, and an ash content of ≤400ppm.

[0011] A second aspect of the present invention provides a method for preparing the above-mentioned polypropylene foamed beads, characterized in that the method includes: foaming a foaming composition containing polypropylene microparticles in the presence of a foaming agent.

[0012] A third aspect of the present invention provides a polypropylene foamed bead molded body, characterized in that the molded body is made from the above-mentioned polypropylene foamed beads.

[0013] The fourth aspect of the present invention provides a method for preparing the above-mentioned polypropylene foamed bead molded body, characterized in that the above-mentioned polypropylene foamed beads are molded and cured in the presence of steam to obtain the polypropylene foamed bead molded body.

[0014] The fifth aspect of the present invention provides the application of the above-mentioned polypropylene foam beads or polypropylene foam bead molded bodies in the production and manufacturing of autoclaved polypropylene foam materials.

[0015] Through the above technical solutions, the polypropylene foamed beads, polypropylene foamed bead molded bodies, preparation methods, and applications provided by the present invention achieve the following beneficial effects:

[0016] (1) The polypropylene foamed beads provided by the present invention are obtained by foaming a foaming composition containing uniform and regular spherical polypropylene microparticles with a particle size of less than 1 mm, thereby eliminating the industry-standard step of first granulating polypropylene powder and then preparing the granules into microparticles. On the one hand, this reduces processing steps, labor intensity and energy consumption, and saves resin raw materials and water resources; more importantly, the obtained foamed beads have a particle size of less than 1 mm, with a minimum particle size of less than 0.05 mm, which is much smaller than the foamed beads (greater than 2 mm) prepared by current technology.

[0017] (2) Since the ash content of the polypropylene microparticles provided by the present invention is ≤400ppm, the pore wall stretching growth is more uniform during the foaming process. The pore wall will not crack due to stress concentration points caused by the presence of too much ash in the melt, thus bringing a higher closed-cell rate to the foamed beads and molded body.

[0018] (3) When the EPP beads prepared by the present invention are used to prepare foamed products in the mold, the particle size is very small, so the void ratio between the particles is very low. The ratio between the packing ratio and the apparent ratio is less than 1.6, which is lower than the ratio of the two of EPP beads prepared by the prior art (>1.8). The contact with molding steam is more sufficient, which can significantly shorten the production time of in-mold molding, reduce the amount of molding steam used, and reduce the energy consumption during in-mold molding.

[0019] (4) The EPP beads prepared by the present invention have small particle size and high closed-cell rate. Therefore, the molded body prepared by using them as raw materials has excellent surface quality, lower shrinkage rate, and better mechanical and thermal insulation properties than the EPP molded body prepared by the prior art at the same ratio.

[0020] (5) The EPP beads prepared by the present invention have a small particle size, so they can be used as raw materials to make thin-walled EPP molded bodies with complex shapes.

[0021] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the bead forming process inside the mold cavity. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] The first aspect of the present invention provides polypropylene foam beads, characterized in that the polypropylene foam beads are obtained by foaming a foaming composition containing polypropylene microparticles.

[0025] The polypropylene microparticles have an average particle size of ≤1mm, an aspect ratio of ≤1.2, and an ash content of ≤400ppm.

[0026] The polypropylene foamed beads provided by this invention are obtained by foaming a foaming composition containing uniformly shaped polypropylene microparticles with a particle size of less than 1 mm. This eliminates the need for the commonly used process of granulating polypropylene powder and then preparing the granules into microparticles. This reduces processing steps, labor intensity and energy consumption, and saves resin raw materials and water resources. Furthermore, due to the low ash content of the polypropylene microparticles, foamed beads with fewer pores on the pore walls can be prepared, thereby improving the various properties of the foamed molded articles. More importantly, the resulting foamed beads have a particle size of less than 1 mm, with a minimum particle size of less than 0.05 mm, which is far smaller than foamed beads (greater than 2 mm) prepared by current technologies.

[0027] Furthermore, the average particle size of the polypropylene microparticles is ≤0.2mm; the aspect ratio of the polypropylene microparticles is ≤1.15; and the ash content of the polypropylene microparticles is ≤350ppm.

[0028] Furthermore, the average particle size of the polypropylene microparticles is ≤0.2mm; the aspect ratio of the polypropylene microparticles is ≤1.1; and the ash content of the polypropylene microparticles is ≤200ppm.

[0029] According to the present invention, the bulk density of the polypropylene microparticles is >0.35 g / cm³. 3 Preferred concentration >0.40 g / cm³ 3 .

[0030] In this invention, at 230°C and a load of 2.16 kg, the melt flow rate index of the polypropylene microparticles is 2-45 g / 10 min, preferably 5-40 g / 10 min.

[0031] Foaming composition

[0032] In this invention, the foaming composition containing polypropylene microparticles further includes conventional additives in the art. Specifically, the foaming composition also includes a dispersion medium, a surfactant, a dispersant, and a dispersion reinforcing agent. Preferably, relative to 100 parts by weight of polypropylene microparticles, the content of the dispersion medium is 1000-10000 parts by weight, the content of the surfactant is 0.1-3 parts by weight, the content of the dispersant is 1-10 parts by weight, and the content of the dispersion reinforcing agent is 0.05-1 parts by weight.

[0033] In this invention, the dispersion medium can be a conventional dispersion medium used in polypropylene foaming compositions, such as deionized water. The surfactant can be a conventional surfactant used in polypropylene foaming compositions, such as sodium dodecylbenzenesulfonate. The dispersant can be a conventional dispersant used in polypropylene foaming compositions, such as kaolin. The dispersion reinforcing agent can be a conventional dispersion reinforcing agent used in polypropylene foaming compositions, such as aluminum sulfate.

[0034] According to the present invention, the particle size of the polypropylene foam beads is 0.03-3 mm; the aspect ratio of the polypropylene foam beads is 1-1.1:1.

[0035] In this invention, the polypropylene foam beads are spherical particles with uniform particle size and small particle size. Therefore, the porosity between particles is very small, which significantly reduces the ratio of the packing ratio to the apparent ratio of the polypropylene foam beads and increases the closed-cell rate of the polypropylene foam beads. Specifically, the ratio of the packing ratio to the apparent ratio of the polypropylene foam beads is ≤1.6, and the closed-cell rate of the polypropylene foam beads is ≥99%.

[0036] Furthermore, the particle size of the polypropylene foam beads is 0.1-1 mm; the aspect ratio of the polypropylene foam beads is 1.01-1.05:1.

[0037] Furthermore, the ratio of the bulk density to the apparent density of the polypropylene foam beads is ≤1.5.

[0038] Furthermore, the closed-cell rate of the polypropylene foam beads is ≥99.5%.

[0039] Polypropylene microparticles

[0040] The present invention does not impose any particular limitation on the preparation method of polypropylene microparticle powder, and it can be prepared by the polypropylene resin polymerization preparation method existing in the art.

[0041] In a preferred embodiment of the present invention, the polypropylene microparticles are prepared by means of polymerizing propylene-containing olefins in the presence of a catalyst.

[0042] In this invention, to obtain a catalyst suitable for olefin polymerization, particularly propylene polymerization, the catalyst preferably contains a spherical support, a titanium halide compound, and an electron donor compound. Preferably, the titanium halide is selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetrabutoxy, titanium tetraethoxy, titanium monochlorotributoxy, titanium dichlorodibutoxy, titanium trichloro-n-butoxy, titanium monochlorotriethoxy, titanium dichlorodiethoxy, titanium trichloroethoxy, and titanium trichloride. Preferably, the electron donor compound is selected from at least one of diisobutyl phthalate, carboxylic acid diol ester, and phosphate ester. Furthermore, this invention does not impose particular limitations on the content of each component in the catalyst; those skilled in the art can make reasonable adjustments and designs according to actual needs.

[0043] In a preferred embodiment of the present invention, propylene-containing olefins are polymerized in the presence of a catalyst and an antioxidant to obtain the polypropylene microparticles. This allows the antioxidant to be directly distributed on the surface and inside the polypropylene microparticles, thereby improving the overall performance of the polypropylene foamed beads and foamed molded articles.

[0044] In this invention, there are no particular restrictions on the type of antioxidant, and those skilled in the art can make reasonable adjustments and designs according to actual needs. Regarding the amount of antioxidant, in order to achieve better overall performance in the polypropylene foamed beads and the molded polypropylene foamed bead body, preferably, based on the amount of polypropylene microparticles, the amount of antioxidant is 0.01wt%-0.5wt%.

[0045] The present invention does not impose any particular limitation on the preparation method of the catalyst, which can be prepared by existing methods for preparing olefin polymerization catalysts in the art. The specific operation process is described in the embodiments below, and should not be construed as a limitation of the present invention by those skilled in the art.

[0046] According to the present invention, the average particle diameter of the spherical carrier is 2-100 micrometers; the particle size distribution is less than 2.

[0047] In this invention, in the presence of a spherical carrier having the above-mentioned average particle diameter and particle size distribution, polypropylene microparticles with good spherical morphology, uniform particle size, average particle size ≤1mm, aspect ratio ≤1.2, and ash content ≤400ppm can be obtained, thereby obtaining polypropylene foamed beads with a particle size of less than 1mm.

[0048] In this invention, the average particle diameter refers to D50.

[0049] In this invention, the particle size distribution is obtained based on (D90-D10) / D50.

[0050] In this invention, the average particle diameter and particle size distribution of the catalyst support are measured using a laser particle size analyzer such as the Master Sizer 2000 laser particle size analyzer (manufactured by Malvern Instruments Ltd).

[0051] Furthermore, the average particle diameter of the spherical carrier is 2-19 micrometers, and the particle size distribution is 0.6-1.6.

[0052] In one specific embodiment of the present invention, the spherical carrier has the structure shown in formula (1):

[0053]

[0054] In equation (1), R1 is selected from C 1-10 Alkyl groups;

[0055] R2 and R3 are each independently selected from H and C. 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 alkyl halogenates;

[0056] R4 is selected from C atoms that are substituted with at least one halogen atom. 1-10 Halogenated alkyl groups and C groups substituted with at least one halogen atom 6-20 Halogenated aromatic groups;

[0057] R5 is selected from C 1-5 Alkyl groups;

[0058] X is selected from fluorine, chlorine, bromine, and iodine;

[0059] m is 0.1-1.9, n is 0.1-1.9, and m+n=2; 0 <q<0.2;0<a<0.1。

[0060] In this invention, in formula (1) Partial representation (OC2H2XR2R3) n .

[0061] In this invention, R1 is selected from C 1-10 The alkyl group, wherein R1 is a straight-chain, branched, or cyclic alkyl group, including but not limited to methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, n-hexyl, isohexyl, cyclohexyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, etc.

[0062] In this article, the alkyl substituents of R1 have similar definitions as described above, except that the number of carbon atoms is different. They will not be described in detail in the following text.

[0063] To obtain a spherical carrier with better performance, R1 is preferably selected from C. 1-8 Alkyl groups; more preferably, R1 is selected from C1. 1-6 Alkyl groups.

[0064] In this invention, R2 and R3 are each independently selected from H and C. 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 alkyl halogenates.

[0065] When R2 and R3 are selected from C 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 When the alkyl group is a haloalkyl group, the alkyl group is a straight-chain or branched group, and the C 1-10 The alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, neopentyl, n-hexyl, isohexyl, 1-ethylpropyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, etc. The haloalkyl group is a straight-chain or branched group, and the C atoms substituted with 1-10 halogen atoms... 1-10 The alkyl halo group refers to C 1-10A group formed by replacing 1-10 hydrogen atoms in an alkyl group with halogen atoms. This replacement can involve multiple hydrogen atoms on the same carbon atom or hydrogen atoms on different carbon atoms. When multiple halogen atoms are substituted, the halogen atoms can be the same or different, and can be fluorine, chlorine, bromine, or iodine atoms. Examples include, but are not limited to, -CF3, -CH2CF3, -CH2CF2H, -CF2CF3, -CF2CH2CF2H, -CH2CF2CF2H, -CH2CH2CH2Cl, and -CH2CH2CH2Br.

[0066] In this article, the alkyl substituents and haloalkyl substituents of R2 and R3 have similar definitions as described above, except that the number of carbon atoms is different. They will not be described in detail below.

[0067] To obtain a spherical carrier with better performance, preferably, R2 and R3 are each independently selected from H and C. 1-5 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-5 alkyl halogenates.

[0068] In this invention, R4 is selected from C atoms substituted with at least one halogen atom. 1-10 Halogenated alkyl groups and C groups substituted with at least one halogen atom 6-20 The halogenated aromatic group. The C group substituted with at least one halogen atom. 1-10 The alkyl halide and C substituted with at least one halogen atom 6-20 The halogenated aromatic group refers to C 1-10 alkyl, C 6-20 A group formed by replacing at least one hydrogen atom in an aromatic group with a halogen atom, wherein the halogen atom is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Wherein, the C... 1-10 The alkyl halogroup can be a straight-chain, branched, or cyclic group, such as, but not limited to, CF3, -CH2CF3, -CH2CF2H, -CF2CF3, -CF2CH2CF2H, -CH2CF2CF2H, -CH2CH2CH2Cl, -CH2CH2CH2Br, etc. The C 6-20 The halogenated aromatic group refers to the halogenated aromatic group containing 6-20 carbon atoms.

[0069] In this article, the substituents of R4 have similar definitions as described above, except that the number of carbon atoms is different. They will not be described in detail in the following text.

[0070] To obtain a spherical support with better performance, R4 is preferably selected from C atoms substituted with at least two halogen atoms. 1-10 Halogenated alkyl groups and C atoms substituted with at least two halogen atoms6-20 The halogenated aromatic group, wherein the halogen atom is preferably selected from at least one of chlorine, bromine and iodine atoms.

[0071] In this invention, the substitution of C by at least two halogen atoms refers to... 1-10 alkyl and C 6-20 At least two hydrogen atoms in the aromatic group are replaced by halogen atoms, wherein the hydrogen atoms can be hydrogen atoms on one carbon or hydrogen atoms on different carbons, and the halogen atoms can be the same or different.

[0072] In this invention, R5 is selected from C. 1-5 alkyl group, the C 1-5 Alkyl groups refer to alkyl groups having 1 to 5 carbon atoms, such as including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, etc.

[0073] In this article, the substituents of R5 have similar definitions as described above, except that the number of carbon atoms is different. They will not be described in detail in the following text.

[0074] To obtain a spherical carrier with better performance, R5 is preferably selected from C. 1-2 Alkyl groups.

[0075] To obtain a spherical carrier with better performance, X is preferably selected from chlorine and bromine.

[0076] In one specific embodiment of the present invention, the method for preparing the spherical carrier includes the following steps:

[0077] (1) Component A is subjected to first contact and emulsification in sequence to obtain a first product, wherein component A contains magnesium halide with the general formula MgXY and a first alcohol compound with the general formula R1OH;

[0078] (2) The first product is brought into a second contact with component B to obtain a second product, wherein component B contains an ethylene oxide compound having the structure shown in formula (2);

[0079] (3) The second product is brought into a third contact with component C to obtain a third product, wherein component C contains a haloalcohol with the general formula R4OH and a second alcohol compound with the general formula R5OH;

[0080] (4) The third product is spray-dried;

[0081]

[0082] In the formula R1OH, R1 is selected from C 1-10 Alkyl groups;

[0083] In equation (2), R2 and R3 are each independently selected from H and C. 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 alkyl halogenates;

[0084] In formula R4OH, R4 is chosen from C atoms substituted with at least one halogen atom. 1-10 Halogenated alkyl groups and C groups substituted with at least one halogen atom 6-20 Halogenated aromatic groups;

[0085] In the formula R5OH, R5 is selected from C. 1-5 Alkyl groups;

[0086] In the formula MgXY, X is selected from fluorine, chlorine, bromine, and iodine; Y is selected from fluorine, chlorine, bromine, iodine, and C. 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl and C 6-14 aryloxy groups;

[0087] The amounts of component A, component B, and component C are such that the resulting spherical carrier has the structure shown in formula (1):

[0088]

[0089] In equation (1), m is 0.1-1.9, n is 0.1-1.9, and m+n=2; <q<0.2;0<a<0.1;

[0090] In step (3), the amount of haloalcohol used is 0.05-6.5 mol relative to 1 mol of magnesium halide, and the amount of the second alcohol compound used is 5-100 mol.

[0091] In this invention, the definitions of the substituent groups R1, R2, R3, R4 and R5 in the preparation method of the spherical carrier correspond to the same definitions of the spherical carrier mentioned above in this invention, and will not be described in detail here.

[0092] In this invention, in the formula MgXY, when Y is selected from C 1-6 alkyl, C 1-6 When the alkoxy group is used, the alkyl group and the alkoxy group are straight-chain or branched alkyl and alkoxy groups, and the C 1-6 The alkyl group refers to an alkyl group having 1-6 carbon atoms, such as, but not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, etc.; the C 1-6Alkoxy refers to an alkoxy group having 1 to 6 carbon atoms, such as including but not limited to methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, n-pentoxy, isopentoxy, etc.

[0093] The C 6-14 The aryl group refers to an aryl group having 6-14 carbon atoms, such as including but not limited to phenyl, o-tolyl, m-tolyl, p-tolyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, naphthyl, etc.

[0094] The C 6-14 The aryloxy group refers to an aryloxy group having 6-14 carbon atoms, such as including but not limited to phenoxy, naphthoxy, o-methylphenoxy, o-ethylphenoxy, m-methylphenoxy, etc.

[0095] In this paper, the substituents of Y in the formula MgXY, such as alkyl, alkoxy, aryl and aryloxy groups, have similar definitions as described above, except that the number of carbon atoms is different. These will not be described in detail in the following text.

[0096] According to a preferred embodiment of the present invention, in the formula MgXY, X is selected from chlorine and bromine, and Y is selected from chlorine, bromine, and C. 1-5 alkyl, C 1-5 alkoxy, C 6-10 aryl and C 6-10 aryloxy groups.

[0097] To obtain spherical carriers with smaller particle size and better performance, more preferably, the magnesium halide is selected from at least one of magnesium chloride, magnesium bromide, magnesium phenoxy chloride, magnesium isopropoxy chloride, and magnesium n-butoxy chloride, and even more preferably magnesium chloride.

[0098] According to another preferred embodiment of the present invention, in the formula R1OH, R1 is selected from C 1-8 Alkyl groups.

[0099] In order to obtain spherical carriers with smaller particle size, more uniform particle size distribution and better performance, more preferably, the first alcohol compound is selected from at least one of ethanol, propanol, isopropanol, n-butanol, isobutanol, pentanol, isoamyl alcohol, n-hexanol, n-octanol and 2-ethylhexanol.

[0100] According to another preferred embodiment of the present invention, in formula (2), R2 and R3 are each independently selected from H and C. 1-5 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-5 alkyl halogenates.

[0101] To obtain spherical carriers with smaller particle size, more uniform particle size distribution, and better performance, more preferably, the ethylene oxide compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, epichlorohydrin, chlorobutane, bromopropane, and bromobutane.

[0102] According to the present invention, the haloalcohol can be a monohaloalcohol or a polyhaloalcohol, preferably a chloroalcohol, a bromoalcohol, or an iodoalcohol, such as 2,2,2-trichloroethanol, 2,2-dichloroethanol, 2-chloroethanol, 3-chloro-1-propanol, 6-chloro-1-hexanol, 3-bromo-1-propanol, 5-chloro-1-pentanol, 4-chloro-1-butanol, 2-chlorocyclohexanol, 1,2-dichloroethanol, 1,3-dichloropropanol, 1,4-dichlorobutanol, or 2-iodoethanol, etc.

[0103] However, in order to obtain a spherical carrier with better performance, according to another preferred embodiment of the present invention, in formula R4OH, R4 is selected from C atoms substituted with at least two halogen atoms. 1-10 Halogenated alkyl groups and C atoms substituted with at least two halogen atoms 6-20 The halogenated aromatic group is selected from at least one of chlorine, bromine and iodine atoms.

[0104] Preferably, the haloalcohol is selected from at least one of 2,2,2-trichloroethanol, 2,2-dichloroethanol, 1,2-dichloroethanol, 1,3-dichloropropanol, and 1,4-dichlorobutanol.

[0105] According to the present invention, the second alcohol compound is selected from C 1-5 At least one of the alcohol compounds, such as ethanol, methanol, n-propanol, isopropanol, n-butanol, or isobutanol. However, in order to obtain a spherical support with better performance, according to another preferred embodiment of the present invention, in formula R5OH, R5 is selected from C 1-2 The alkyl group, i.e., the second alcohol compound, is methanol and / or ethanol.

[0106] According to the present invention, the inventors have discovered that when the amount of the haloalcohol compound and the alcohol compound is too large, the resulting spherical carrier becomes agglomerated and cannot be used for subsequent operations.

[0107] Preferably, relative to 1 mol of the magnesium halide, the amount of the first alcohol compound is 1-30 mol, and the amount of the ethylene oxide compound is 1-10 mol.

[0108] More preferably, relative to 1 mol of the magnesium halide, the amount of the first alcohol compound is 6-22 mol, the amount of the ethylene oxide compound is 2-6 mol, the amount of the haloalcohol is 1-5 mol, and the amount of the second alcohol compound is 8-80 mol, more preferably 31-50 mol.

[0109] In this invention, it should be noted that the trace amounts of water carried in the reactants will also participate in the reaction to form the spherical carrier. Therefore, the prepared spherical carrier may contain trace amounts of water from the reactants and reaction medium. This should not be construed as a limitation of the invention by those skilled in the art.

[0110] Preferably, in step (1), the first contact is carried out under stirring conditions, which include a temperature of 80-120°C and a time of 0.5-5h.

[0111] More preferably, in step (1), the conditions for the first contact include: a temperature of 80-100°C and a time of 0.5-3h.

[0112] In step (1), the present invention does not particularly limit the specific operation method of emulsification, and methods known to those skilled in the art can be used. For example, emulsification can be performed using low-speed shearing or high-speed shearing. Preferably, when using low-speed shearing, the stirring rate of the low-speed shearing is 400-800 rpm. The method of high-speed shearing is known to those skilled in the art, for example, using the high-speed stirring speed disclosed in CN1330086A. In addition, the emulsification operation can also be performed with reference to the methods disclosed in the following patent applications, such as the rotary dispersion of a solution containing liquid magnesium halide compounds in a hypergravity bed (rotation speed of 100-3000 rpm) disclosed in CN1580136A; another example is the output of a solution containing liquid magnesium halide adducts in an emulsifier at a speed of 1500-8000 rpm disclosed in CN1463990A; and yet another example is the emulsification of a solution containing liquid magnesium halide adducts by spraying method disclosed in US6020279A.

[0113] Preferably, in step (2), the conditions for the second contact include: a temperature of 50-120°C and a time of 20-60 min;

[0114] More preferably, in step (2), the conditions for the second contact include: a temperature of 80-100°C and a time of 20-50 min.

[0115] According to a preferred embodiment of the present invention, step (3) further includes washing the second product with an inert solvent and then making the third contact with each component in component C. Preferably, the inert solvent is selected from at least one of pentane, hexane, heptane, petroleum ether and gasoline.

[0116] The present invention does not impose any particular restrictions on the specific conditions of the third contact in step (3), as long as the component C and the second product can be fully contacted to form a fluid. However, in order to have a catalyst support with better performance, preferably, the conditions of the third contact in step (3) include: being carried out under stirring conditions, with a temperature of 0-120°C and a time of 0.5-6h.

[0117] The present invention does not impose any particular restrictions on the specific method of the third contact in step (3). The haloalcohol and the second alcohol compound can be mixed and contacted with the second component simultaneously, or the haloalcohol and the second alcohol compound can be contacted with the second component separately in sequence.

[0118] In this invention, the spray drying conditions can employ existing conditions capable of forming spherical carriers for olefin polymerization. However, to obtain spherical carriers with better performance, according to a preferred embodiment of the invention, the spray drying is carried out in a sprayer with an atomizing nozzle. The atomizing nozzle includes a material conduit and a nozzle head. The third product is led to the nozzle head through the material conduit and sprayed through the nozzle head into a tower containing an inert medium within the sprayer for solidification. Preferably, the temperature of the third product in the material conduit is between 0°C and 80°C, and the temperature of the third product in the nozzle head is 80-180°C; more preferably, the temperature of the third product in the nozzle head is 120-180°C.

[0119] In this invention, in step (4), preferably, the conditions for spray drying include a temperature of 60-200°C, more preferably 90-150°C. In this invention, the temperature of spray drying refers to the temperature of the inert medium in the sprayer.

[0120] In this invention, the inert medium may include a protective gas medium and / or an inert liquid medium. There is no particular limitation on the type of the protective gas medium. For example, it may be nitrogen, an inert gas medium such as helium, or other suitable gases such as carbon dioxide. The inert liquid medium is a liquid medium commonly used in the art that does not chemically react with reactants and reaction products. Preferably, the inert liquid medium is silicone oil and / or an inert liquid hydrocarbon solvent. More preferably, the inert liquid medium is selected from at least one of kerosene, paraffin oil, petrolatum oil, white oil, methyl silicone oil, ethyl silicone oil, methyl ethyl silicone oil, phenyl silicone oil, and methyl phenyl silicone oil. Even more preferably, white oil is selected.

[0121] In this invention, the amount of inert liquid medium in the sprayer can be selected according to the amount of magnesium halide with the general formula MgXY, preferably 0.8-10L, more preferably 2-8L.

[0122] The method for preparing the spherical carrier described in this invention also includes conventional post-processing methods in the art, such as solid-liquid separation, washing, and drying, and this invention does not impose any particular limitations on these methods. The solid-liquid separation can employ various existing methods capable of separating the solid and liquid phases, such as vacuum filtration, pressure filtration, or centrifugation. Preferably, the solid-liquid separation method is pressure filtration. This invention does not particularly limit the conditions for pressure filtration, aiming to achieve the most complete separation of the solid and liquid phases possible. The washing can be performed using methods known to those skilled in the art to wash the obtained solid product, for example, using inert hydrocarbon solvents (such as pentane, hexane, heptane, petroleum ether, and gasoline). This invention does not particularly limit the specific conditions for drying; for example, the drying temperature can be 20-70°C, the drying time can be 0.5-10 hours, and the drying can be carried out under normal or reduced pressure conditions.

[0123] The inventors discovered that by using specific types and amounts of alcohol compounds and haloalcohol compounds in combination with components such as magnesium halides and ethylene oxide compounds, and simultaneously matching a specific spray drying method, it is possible to obtain spherical carriers with novel compositions and good particle morphology, wherein the spherical carriers are basically free of irregular particles; and the preparation process does not require the addition of surfactants and is stable.

[0124] In particular, the method provided by the present invention can prepare spherical supports with very small particle sizes, which greatly expands the range of particle sizes that can be prepared for the supports; and the catalyst prepared by the spherical supports has high hydrogen sensitivity when used for olefin polymerization.

[0125] A second aspect of the present invention provides a method for preparing the above-mentioned polypropylene foamed beads, characterized in that the method includes: foaming a foaming composition containing polypropylene microparticles in the presence of a foaming agent.

[0126] According to some specific embodiments of the present invention, the foamed beads can be produced by impregnation foaming in a reaction vessel, and the foaming conditions can be conventionally selected in the art. The specific process is known to those skilled in the art and will not be described in detail here.

[0127] When the polypropylene composition is formed into foamed beads, a foaming agent is typically added. The foaming agent can be a chemical foaming agent or a physical foaming agent, and the physical foaming agent can be an organic or inorganic physical foaming agent. Examples of chemical foaming agents include, but are not limited to, at least one of azoformamide (AC foaming agent), p-toluenesulfonyl hydrazine, aminoureas, tetrazolium, sodium bicarbonate, and sodium citrate. Examples of organic physical foaming agents include, but are not limited to, at least one of aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclobutane and cyclohexane; and halogenated hydrocarbons such as at least one of chlorofluoromethane, trifluoromethane, 1,2-difluoroethane, 1,2,2,2-tetrafluoroethane, methyl chloride, ethyl chloride, and dichloromethane. Examples of inorganic physical foaming agents include, but are not limited to, at least one of air, nitrogen, carbon dioxide, oxygen, and water.

[0128] In one specific embodiment of the present invention, the foaming temperature is 120-180℃; the foaming pressure is 0.5-16MPa; and the saturated impregnation time of the foaming is 1-90min.

[0129] Furthermore, the foaming temperature is 130-170℃; the foaming pressure is 1.5-10MPa; and the saturated impregnation time is 5-60min.

[0130] A third aspect of the present invention provides a polypropylene foamed bead molded body, characterized in that the molded body is made from the above-mentioned polypropylene foamed beads.

[0131] In this invention, the molded body is obtained by molding the above-mentioned polypropylene foamed beads.

[0132] In this invention, the molding process can be carried out in various existing molding machines, and the molding conditions can be conventionally selected in the field, which will be known to those skilled in the art and will not be elaborated here.

[0133] According to the present invention, the shrinkage rate of the polypropylene foamed beads is ≤1.5, preferably ≤1.2.

[0134] The fourth aspect of the present invention provides a method for preparing polypropylene foamed beads, characterized in that the polypropylene foamed beads are shaped and cured in the presence of steam to obtain the polypropylene foamed beads.

[0135] According to the present invention, the pressure of the steam is 1.3-1.8 kg; preferably 1.2-1.6 kg.

[0136] According to the present invention, the molding conditions include: a molding temperature of 110-130°C, preferably 115-125°C, and a molding time of 5-20 min, preferably 8-15 min.

[0137] According to the present invention, the curing conditions include: a curing temperature of 80-120°C, preferably 90-110°C; a curing time of 12-36 h, preferably 18-30 h; and a curing pressure of 1-1.1 atm, preferably 1-1.05 atm.

[0138] The fifth aspect of the present invention provides the application of the above-mentioned polypropylene foam beads or the above-mentioned polypropylene foam bead molded body in the production and manufacturing of autoclaved polypropylene foam materials.

[0139] In the following embodiments and comparative examples, the relevant data were obtained using the following test methods:

[0140] 1. Average particle diameter and particle size distribution of catalyst support: measured using a Masters Sizer 2000 particle size analyzer manufactured by Malvern Instruments.

[0141] 2. Morphology of the catalyst support: Observed using an XL-30 field emission electron microscope manufactured by FEI Corporation, USA;

[0142] 3. Structure and composition of catalyst support: The support was analyzed by 1H-NMR using an AVANCE 300 nuclear magnetic resonance spectrometer from Bruker, Switzerland, and by a PY-2020iD pyrolyzer from Fronteerlab, a TraceGC Ultra chromatograph from Thermo Fisher, and a DSQⅡ mass spectrometer.

[0143] 4. Catalyst activity: evaluated by the ratio of the weight of the product obtained after polymerization to the weight of the catalyst used;

[0144] 5. Bulk density of polypropylene microparticles and polypropylene foamed beads: The bulk density is determined according to the method specified in GB / T 1636-2008. In general, the foaming industry uses 0.9 divided by the bulk density of the foamed beads to define the bulk expansion ratio of the foamed beads.

[0145] 6. Melt flow rate index of polypropylene microparticles: measured according to ISO 1133, 230℃, 2.16kg load;

[0146] 7. The compressive strength of the foamed molded body shall be measured according to the method of GB / T8813-2008 for the determination of compressive properties of rigid foamed plastics, and the flexural strength of the foamed molded body shall be measured according to the method of GB / T 8812-2007 for the determination of flexural properties of rigid foamed plastics.

[0147] 8. Test method for apparent expansion ratio of foamed beads: The apparent density of polypropylene foamed beads is obtained by water displacement method using the density accessory YDK01 of the German Satorius CPA225D balance. The measurement is carried out according to the methods described in national standard GB / T1033.1-2008 and ISO1183-1:2012. In general, the foaming industry uses 0.9 divided by the apparent density of foamed beads to define the apparent expansion ratio of foamed beads.

[0148] 9. Scanning Electron Microscope: XL-30, FEI Corporation, USA. Test Method: The particle size and aspect ratio of polypropylene microparticles in the examples and comparative examples were examined using a scanning electron microscope (SEM).

[0149] 10. The thermal conductivity was tested according to the heat flow meter method of GB / T10295-2008 Determination of steady-state thermal resistance and related properties of thermal insulation materials. The sample size was 500mm×500mm×25mm.

[0150] 11. Closed-Porosity Tester: ULTRAFOAM 1200e, Quantachrome Instruments, USA. Testing was conducted according to GB / T10799-2008. Applying Archimedes' principle—the gas expansion and displacement method—it utilizes Bohr's law (PV = nRT) for small-molecule inert gases under certain conditions. The sample's skeletal volume (including closed pores) is accurately determined by measuring the decrease in gas volume in the sample testing chamber caused by the insertion of the sample, thus obtaining its true density. True density = mass / skeletal volume. The closed-porosity of the sample is obtained by comparing the true density with the apparent density.

[0151] 12. Determination of Ash Content in Polypropylene Microparticles: The direct calcination method in GB / T 9345.1-2008 "Determination of Ash Content in Plastics Part 1: General Method" was adopted. The crucible was calcined at 900℃ until constant weight, and the mass of the crucible and the total mass after adding the sample were recorded. The sample and crucible were then calcined at 600℃ until constant weight, and the mass of the crucible and sample was recorded again. The entire assembly was then calcined at 850℃ until constant weight. After cooling in a desiccator, the mass of the crucible and sample was recorded. The ash content of the sample was obtained by dividing the mass of the calcined sample by the mass of the sample before calcination.

[0152] In the following examples, unless otherwise specified, emulsification was carried out by stirring at 600 rpm during the preparation of the catalyst support.

[0153] The materials used in the following embodiments and comparative examples are as follows:

[0154] In the following examples, unless otherwise specified, all raw materials used are commercially available products.

[0155] 1,3-Dichloropropanol was purchased from Bailingwei Company;

[0156] Epichlorohydrin was purchased from Bailingwei Company;

[0157] Diisobutyl phthalate was purchased from Bailingwei Company;

[0158] Titanium tetrachloride was purchased from Bailingwei Company;

[0159] Triethylaluminum was purchased from Bailingwei Company;

[0160] Methylcyclohexyldimethoxysilane was purchased from Bailingwei Company.

[0161] Antioxidant 1010, manufactured by BASF Ciba in Germany;

[0162] The polypropylene used is FL7540l from TPC Singapore, with a melting point of 138℃ and a melt index of 8 g / 10 min.

[0163] Example 1 of catalyst microsphere support preparation

[0164] (1) In a 0.6L reactor, add 0.08mol magnesium chloride and 1.7mol ethanol (first alcohol compound), heat to 90℃ with stirring, and react at a constant temperature for 1h to carry out the first contact, and then emulsify to obtain the first product;

[0165] (2) The first product is subjected to a second contact with 0.48 mol of epichlorohydrin to obtain a second product. The conditions for the second contact are: temperature of 90°C and time of 30 min.

[0166] (3) After the second product is filtered, it is thoroughly mixed and stirred with 2.5 mol of ethanol (second alcohol compound) and 0.35 mol of 1,3-dichloropropanol (halogenated alcohol) to form a third fluid and obtain the third product;

[0167] (4) The third product is sprayed into the spray tower of the sprayer tower at 100°C using a sprayer B-290 containing a nozzle head and a material conduit for spray drying. The temperature of the third product in the material conduit is 15°C and the temperature in the nozzle head is 120°C, to obtain a spherical carrier Z1.

[0168] The structure and composition of the obtained spherical catalyst support Z1 were determined by testing as follows:

[0169]

[0170] Tests showed that the average particle diameter (D50) of the spherical catalyst support Z1 was 4 micrometers, and the particle size distribution ((D90-D10) / D50) was 0.9.

[0171] Observations showed that the spherical catalyst support Z1 had a relatively regular particle shape, a smooth surface, and was mostly spherical. The particle size distribution was relatively concentrated, and there were basically no irregularly shaped particles.

[0172] During the preparation of the catalyst spherical support Z1, no clogging occurred at the nozzle head of the sprayer, and a total of 11.8g of support Z1 was obtained.

[0173] Example 2 of catalyst microsphere support preparation

[0174] (1) In a 0.6L reactor, add 0.08mol magnesium chloride and 1.4mol ethanol (first alcohol compound), heat to 90℃ with stirring, and react at a constant temperature for 1.5h to carry out the first contact. Then, emulsify to obtain the first product.

[0175] (2) The first product is subjected to a second contact with 0.35 mol epichlorohydrin to obtain a second product. The conditions for the second contact are: temperature of 90°C and time of 30 min.

[0176] (3) After the second product is filtered, it is thoroughly mixed and stirred with 2.5 mol of ethanol (second alcohol compound) and 0.25 mol of 1,3-dichloropropanol (halogenated alcohol) to form a third fluid and obtain the third product;

[0177] (4) The third product is sprayed into the spray tower of the sprayer tower at 100°C using a sprayer B-290 containing a nozzle head and a material conduit for spray drying. The temperature of the third product in the material conduit is 15°C and the temperature in the nozzle head is 120°C, thus obtaining the catalyst spherical support Z2.

[0178] The structure and composition of the obtained spherical catalyst support Z2 were determined by testing as follows:

[0179]

[0180] Tests showed that the average particle diameter (D50) of the spherical catalyst support Z2 was 4 micrometers, and the particle size distribution ((D90-D10) / D50) was 0.8.

[0181] Observations showed that the spherical carrier Z2 for olefin polymerization has a relatively regular particle shape, a smooth surface, and is basically spherical. The particle size distribution is relatively concentrated, and there are basically no irregular particles.

[0182] During the preparation of the catalyst spherical support Z2, no clogging occurred at the nozzle head of the sprayer, and a total of 11.9g of the catalyst spherical support Z2 was obtained.

[0183] Example 3 of catalyst microsphere support preparation

[0184] (1) In a 0.6L reactor, add 0.08mol magnesium chloride and 1.4mol ethanol (first alcohol compound), heat to 90℃ with stirring, and react at a constant temperature for 1.5h to carry out the first contact, and then emulsify to obtain the first product;

[0185] (2) The first product is brought into a second contact with 0.35 mol epichlorohydrin to obtain a second product. The conditions for the second contact are: temperature of 90°C and time of 30 min.

[0186] (3) After the second product is filtered, it is mixed with 2.5 mol of ethanol (second alcohol compound) and 0.1 mol of 1,3-dichloropropanol (halogenated alcohol) and stirred until a third contact is made to form a fluid, thereby obtaining the third product;

[0187] (4) The third product is sprayed into the circulating nitrogen gas at 100°C in the spray tower using a sprayer B-290 containing a nozzle head and a material conduit. The temperature of the third product in the material conduit is 15°C and the temperature in the nozzle head is 120°C, to obtain a spherical carrier Z3.

[0188] The structure and composition of the obtained spherical catalyst support Z3 were determined by testing as follows:

[0189]

[0190] Tests showed that the average particle diameter (D50) of the spherical catalyst support Z3 was 5 micrometers, and the particle size distribution ((D90-D10) / D50) was 0.8.

[0191] Observations showed that the spherical catalyst support Z3 had a relatively regular particle shape, a smooth surface, and was mostly spherical. The particle size distribution was relatively concentrated, and there were basically no irregularly shaped particles.

[0192] During the preparation of the catalyst spherical support Z3, no clogging occurred at the nozzle head of the sprayer, and a total of 12.0 g of the catalyst spherical support Z3 was obtained.

[0193] Comparative Example 1 of Catalyst Microsphere Support

[0194] (1) In a 0.6L reactor, add 0.08mol magnesium chloride and 1.6mol ethanol, and heat to 80℃ with stirring. After reacting at a constant temperature for 1 hour, add 0.2mol ethylene oxide and react for 0.5 hours to form a fluid mixture;

[0195] (2) The fluid mixture is sprayed into circulating nitrogen gas at 100°C using a sprayer containing a nozzle head and a material conduit. The temperature of the fluid mixture in the material conduit is 60°C and the temperature in the nozzle head is 160°C, to obtain catalyst support DZ1 for olefin polymerization.

[0196] During the spraying process, no clogging occurred at the nozzle of the sprayer. The obtained cured product was washed four times with hexane and vacuum dried for 1 hour to obtain 12g of catalyst support DZ1.

[0197] The catalyst support DZ1 for olefin polymerization has an average particle diameter (D50) of 15 micrometers and a particle size distribution ((D90-D10) / D50) of 1.3.

[0198] Comparative Example 2 of Catalyst Microsphere Support

[0199] The catalyst spherical support was prepared in a manner similar to that in Example 1, except that in step (3), the second alcohol compound was not used, but only a haloalcohol (1,3-dichloropropanol) was used to thoroughly mix and stir with the second product for the third contact, and the amount of haloalcohol used was the same as in Example 1, thus obtaining catalyst support DZ2.

[0200] During the preparation of catalyst support DZ2, the support clumps together, making subsequent operations impossible.

[0201] Example 1 of polypropylene microparticle preparation

[0202] (1) Preparation of catalysts for olefin polymerization

[0203] In a 300 mL reaction flask, 100 mL of titanium tetrachloride was added and cooled to -20 °C. 8 g of the spherical catalyst support Z1 obtained from Catalyst Microsphere Support Preparation Example 1 was then added, and the mixture was stirred at -20 °C for 30 min. The temperature was then slowly increased to 110 °C, and 1.5 mL of diisobutyl phthalate was added during the heating process. The mixture was maintained at 110 °C for 30 min, and the liquid was filtered off. The mixture was then washed twice with 90 mL of titanium tetrachloride, and finally three times with hexane, and dried to obtain catalyst C1 for olefin polymerization.

[0204] (2) Propylene polymerization reaction

[0205] In a 5L stainless steel high-pressure reactor, under a nitrogen protective atmosphere, 1 mmol of triethylaluminum in hexane solution (triethylaluminum concentration 0.5 mmol / mL), 0.05 mmol of methylcyclohexyldimethoxysilane, 10 mL of anhydrous hexane, 0.5 g of antioxidant 1010, 10 mg of the olefin polymerization catalyst C1 obtained in step (1), 1.5 L (standard volume) of hydrogen, and 2.5 L of liquid propylene monomer were added. The temperature was raised to 70°C, and the reaction was carried out at this temperature for 1 h. Then, the temperature was lowered, the pressure was released, the material was discharged, and dried to obtain 322 g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.16 wt%.

[0206] The catalyst prepared in this test example has an activity of 32.2 kgPP / g·Cat;

[0207] The bulk density of the obtained polypropylene microparticles was 0.41 g / cm³. 3 The melt flow rate index is 10.1 g / 10 min. The polypropylene particles have good morphology, with virtually no irregular shapes. The average particle size is 0.150 mm, the aspect ratio is 1.02, and the ash content is 190 ppm. See Table 1 for details.

[0208] Example 2 of polypropylene microparticle preparation

[0209] Polypropylene was prepared in a manner similar to that in Example 1 of polypropylene microparticle preparation, except that the volume of hydrogen used in step (2) was different, while the rest were the same as in Example 1 of polypropylene microparticle preparation.

[0210] Specifically: 1.5L (standard volume) of hydrogen was replaced with 6.5L (standard volume) of hydrogen to obtain 320g of polypropylene powder microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant was 0.16wt%.

[0211] The catalyst prepared in this test example has an activity of 32.0 kgPP / g·Cat;

[0212] The bulk density of the obtained polypropylene powder particles was 0.41 g / cm³. 3 The melt flow rate index is 40.4 g / 10 min. The polypropylene powder has good particle morphology, with almost no irregular particles. The average particle size is 0.150 mm, the aspect ratio is 1.15, and the ash content is 190 ppm. See Table 1 for details.

[0213] Example 3 of polypropylene microparticle preparation

[0214] Polypropylene was prepared in a manner similar to that in Example 1 of polypropylene microparticle preparation, except that the type of catalyst support used in step (1) was different, while the rest were the same as in Example 1 of polypropylene microparticle preparation.

[0215] Specifically: the catalyst spherical support Z2 prepared in Example 2 was used to replace the catalyst spherical support Z1 to obtain olefin polymerization catalyst C2; then, 329g of polypropylene powder microparticles were prepared using olefin polymerization catalyst C2 according to step (2) of polypropylene microparticle preparation Example 1. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.15wt%.

[0216] The catalyst prepared in this test example has an activity of 32.9 kgPP / g·Cat;

[0217] The bulk density of the obtained polypropylene powder particles was 0.41 g / cm³. 3 The melt flow rate index is 9.8 g / 10 min. The polypropylene powder has good particle morphology, with almost no irregular particles. The average particle size is 0.086 mm, the aspect ratio is 1.04, and the ash content is 180 ppm. See Table 1 for details.

[0218] Example 4 of polypropylene microparticle preparation

[0219] Polypropylene was prepared in a manner similar to that in Example 3 of polypropylene microparticle preparation, except that the volume of hydrogen gas used in step (2) was different, while the rest was the same as in Example 3 of polypropylene microparticle preparation.

[0220] Specifically: 1.5L (standard volume) of hydrogen was replaced with 6.5L (standard volume) of hydrogen to obtain 327g of polypropylene powder microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.15wt%.

[0221] The catalyst prepared in this test example has an activity of 32.7 kgPP / g·Cat;

[0222] The bulk density of the obtained polypropylene powder particles was 0.41 g / cm³. 3The melt flow rate index is 36.7 g / 10 min. The polypropylene powder has good particle morphology, with almost no irregular particles. The average particle size is 0.018 mm, the aspect ratio is 1.01, and the ash content is 150 ppm. See Table 1 for details.

[0223] Example 5 of polypropylene microparticle preparation

[0224] Polypropylene was prepared in a manner similar to that in Example 1 of polypropylene microparticle preparation, except that the type of catalyst support used in step (1) was different, while the rest were the same as in Example 1 of polypropylene microparticle preparation.

[0225] Specifically: the catalyst spherical support Z3 prepared in Example 3 was used to replace the catalyst spherical support Z1 to obtain olefin polymerization catalyst C3; then, 334g of polypropylene powder microparticles were prepared using olefin polymerization catalyst C3 according to step (2) of polypropylene microparticle preparation Example 1. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.15wt%.

[0226] The catalyst prepared in this test example has an activity of 33.4 kgPP / g·Cat;

[0227] The bulk density of the obtained polypropylene powder particles was 0.41 g / cm³. 3 The melt flow rate index is 8.8 g / 10 min. The polypropylene powder has good particle morphology, with almost no irregular particles. The average particle size is 0.066 mm, the aspect ratio is 1.02, and the ash content is 190 ppm. For details, please refer to Table 1.

[0228] Example 6 of polypropylene microparticle preparation

[0229] Polypropylene was prepared in a manner similar to that in Example 5 of polypropylene microparticle preparation, except that the volume of hydrogen used in step (2) was different, while the rest were the same as in Example 5 of polypropylene microparticle preparation.

[0230] Specifically: 1.5L (standard volume) of hydrogen was replaced with 6.5L (standard volume) of hydrogen to obtain 331g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.15wt%.

[0231] The catalyst prepared in this test example has an activity of 33.1 kgPP / g·Cat;

[0232] The bulk density of the obtained polypropylene microparticles was 0.41 g / cm³. 3The melt flow rate index is 35.8 g / 10 min. The polypropylene microparticles have good particle morphology, with almost no irregularly shaped particles. The average particle size is 0.052 mm, the aspect ratio is 1.05, and the ash content is 170 ppm. For details, please refer to Table 1.

[0233] Example 7 of polypropylene microparticle preparation

[0234] Polypropylene microparticles were prepared in a manner similar to that in Example 1, except that in step (2), 1.25 mmol of a triethylaluminum hexane solution (the concentration of triethylaluminum was 0.5 mmol / mL) was added to obtain 322 g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.16 wt%.

[0235] The catalyst prepared in this test example has an activity of 32.2 kgPP / g·Cat;

[0236] The bulk density of the obtained polypropylene microparticles was 0.40 g / cm³. 3 The melt flow rate index is 10.3 g / 10 min. The polypropylene microparticles have good particle morphology, with almost no irregularly shaped particles. The average particle size is 0.138 mm, the aspect ratio is 1.07, and the ash content is 370 ppm. For details, please refer to Table 1.

[0237] Example 8 of polypropylene microparticle preparation

[0238] Polypropylene microparticles were prepared in a manner similar to that in Example 1, except that the amount of antioxidant added in step (2) was 1 g, yielding 322 g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.31 wt%.

[0239] The catalyst prepared in this test example has an activity of 32.2 kgPP / g·Cat;

[0240] The bulk density of the obtained polypropylene microparticles was 0.40 g / cm³. 3 The melt flow rate index is 8.1 g / 10 min. The polypropylene microparticles have good particle morphology, with almost no irregularly shaped particles. The average particle size is 0.125 mm, the aspect ratio is 1.09, and the ash content is 250 ppm (0.030 wt%). See Table 1 for details.

[0241] Example 9 of polypropylene microparticle preparation

[0242] Polypropylene microparticles were prepared in a manner similar to that in Example 1, except that in step (2), the reaction was carried out at 70°C for 0.5 h, yielding 322 g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant used was 0.16 wt%.

[0243] The catalyst prepared in this test example has an activity of 32.2 kgPP / g·Cat;

[0244] The bulk density of the obtained polypropylene microparticles was 0.41 g / cm³. 3 The melt flow rate index is 11.5 g / 10 min. The polypropylene microparticles have good particle morphology, with almost no irregularly shaped particles. The average particle size is 0.109 mm, the aspect ratio is 1.18, and the ash content is 190 ppm. For details, please refer to Table 1.

[0245] Comparative Example 1 of Polypropylene Microparticles

[0246] (1) Preparation of catalysts for olefin polymerization

[0247] In a 300 mL reaction flask, 100 mL of titanium tetrachloride was added and cooled to -20 °C. 8 g of catalyst support DZ1 was added and stirred at -20 °C for 30 min. Then, the temperature was slowly increased to 110 °C. During the heating process, 1.5 mL of diisobutyl phthalate was added. The temperature was maintained at 110 °C for 30 min, and the liquid was filtered off. Then, 90 mL of titanium tetrachloride was added to wash twice, and finally, the mixture was washed three times with hexane and dried to obtain catalyst DC1 for olefin polymerization.

[0248] (2) Preparation of polypropylene microparticles: The method was the same as in Example 1, except that olefin polymerization catalyst DC1 was used to prepare 313g of polypropylene microparticles. Based on the amount of polypropylene microparticles used, the amount of antioxidant was 0.16wt%.

[0249] The catalyst prepared in this comparative example has an activity of 31.3 kgPP / g·Cat;

[0250] The bulk density of the obtained polypropylene microparticles was 0.39 g / cm³. 3 The polypropylene microparticles exhibit a well-defined spherical morphology under an optical microscope, with virtually no irregularly shaped particles. The average particle size is 0.085 mm, the melt flow rate index is 8.2 g / 10 min, the aspect ratio is 1.22, and the ash content is 430 ppm (0.043 wt%). See Table 1 for details.

[0251] Comparative Example 2 of Polypropylene Microparticles

[0252] Polypropylene was prepared in a manner similar to that in Example 1 of polypropylene microparticle preparation, except that in step (2), a catalyst C1 for olefin polymerization was used instead of DQ catalyst purchased from Sinopec Catalyst Beijing Aoda Branch.

[0253] The DQ catalyst contained a spherical support with an average particle diameter (D50) of 65 micrometers and a particle size distribution ((D90-D10) / D50) of 1.6; all other components were the same as in Example 1 of polypropylene microparticle preparation. 485 g of polypropylene microparticles were obtained. Based on the amount of polypropylene microparticles used, the amount of antioxidant was 0.1 wt%.

[0254] The catalyst prepared in this test example has an activity of 48.5 kgPP / g·Cat;

[0255] The bulk density of the obtained polypropylene powder particles was 0.46 g / cm³. 3 The melt flow rate index was 5.1 g / 10 min, the average particle size was 1.8 mm, the ash content was 550 ppm (0.055 wt%), and the aspect ratio was 1.27. For details, please refer to Table 1.

[0256] Comparative Example 3 of Polypropylene Microparticles

[0257] 100 parts of polypropylene FL7540L were mixed with antioxidants (0.1 parts hindered phenolic antioxidant 1010 and 0.05 parts phosphite antioxidant 168) in a high-speed mixer. The mixture was then melted in a twin-screw extruder at 300 rpm and a die temperature of 200°C. After pelletizing, 1 kg of polypropylene microparticles were obtained. The melt flow rate index was 8.63 g / 10 min, and the bulk density was 0.30 g / cm³. 3 The average particle size was 1.57 mm, the aspect ratio was 2.49, and the ash content was 830 ppm (0.083 wt%).

[0258] Comparative Example 4 of Polypropylene Microparticles

[0259] 100 parts of polypropylene FL7540L were mixed with antioxidants (0.1 parts hindered phenolic antioxidant 1010 and 0.05 parts phosphite antioxidant 168) in a high-speed mixer. The mixture was then melted in a twin-screw extruder at 300 rpm, and subsequently fed into a LabLine100 underwater microparticle preparation system. The extrusion temperature was 235℃, and the torque was controlled at approximately 65%. Underwater pelletizing yielded 1 kg of polypropylene microparticles. The melt flow rate index was 8.58 g / 10 min, and the bulk density was 0.34 g / cm³. 3 The average particle size is 0.95 mm, the aspect ratio is 1.68, and the ash content is 780 ppm (0.078 wt%).

[0260] Table 1

[0261]

[0262] Test Case I

[0263] Examples and comparative examples of autoclaved foam beads

[0264] In an autoclave, a certain amount of the polypropylene microparticles prepared in the above-mentioned example or comparative example were added and mixed at once with 300g of dispersion medium (deionized water), 0.3g of surfactant (sodium dodecylbenzenesulfonate), 6g of dispersant (kaolin), and 0.12g of dispersion enhancer (aluminum sulfate). CO2 was used as a foaming agent to remove residual air from the reactor. After removing the air, the reactor lid was tightened. Carbon dioxide was fed into the autoclave, and the pressure was initially adjusted until it stabilized. The dispersion in the autoclave was then stirred and heated at a constant foaming temperature and 4MPa foaming pressure for 0.5 hours. Then, the outlet of the autoclave was opened, allowing the material in the reactor to drain into a collection tank to obtain polypropylene foam beads EPP-A1 to EPP-D8. The feed amount of microparticles, foaming temperature and pressure, foaming ratio, particle size, and aspect ratio of the foam beads are shown in Table 2.

[0265] Table 2

[0266]

[0267] As shown in Table 2, by controlling the particle morphology of the olefin polymerization catalyst support during polypropylene polymerization, uniformly shaped spherical polypropylene microparticles with a particle size ranging from a minimum of 0.01 mm to a maximum of 0.5 mm can be directly prepared for EPP foaming. This eliminates the industry-standard step of first granulating polypropylene powder and then preparing the granules into microparticles. The lowest particle size of the foamed beads that can be obtained directly is less than 0.05 mm, which is much smaller than the foamed beads (above 1.5 mm) prepared by current technologies. In particular, the polypropylene microparticles described in this invention have low ash content, resulting in a significantly improved closed-cell rate for the EPP foamed beads prepared from these polypropylene microparticles.

[0268] Among them, compared with the EPP beads made from the polypropylene microparticles provided in Preparation Example 1, the polypropylene microparticles prepared in Preparation Examples 7 and 8, due to their higher ash content, resulted in a significantly lower closed-cell rate for similar EPP beads under the same foaming process conditions. Furthermore, the polypropylene microparticles prepared in Preparation Example 9 had a large aspect ratio, leading to a larger aspect ratio in the EPP beads made from them.

[0269] The spherical polypropylene microparticles used in this invention have a small diameter, making it difficult for them to collide with each other. Therefore, even with a large feed volume, it is still possible to obtain EPP foam beads that meet the requirements, thereby improving production efficiency. Test examples I-D6 and I-D8 show that currently, commonly used raw material microparticles cannot produce qualified EPP beads at this feed volume.

[0270] Test Case II

[0271] Examples and comparative examples of foamed bead moldings

[0272] 1 kg of foamed beads obtained from the different foaming processes described above were molded using a molding machine under a certain steam pressure and time. The resulting molded body was then cured for 24 hours at 100℃ and standard atmospheric pressure to obtain the foamed bead molded body. The molding steam pressure and holding time, as well as the compressive strength and flexural strength of the foamed bead molded body, are shown in Table 3.

[0273] Table 3

[0274]

[0275]

[0276] As shown in Table 3, the EPP beads prepared by this invention, when used in in-mold molding to produce foamed products, have a smaller particle size, resulting in a lower proportion of voids when the beads are stacked compared to EPP beads prepared by existing technologies. This allows for more thorough contact with molding steam, significantly shortening the in-mold molding production time, reducing the amount of molding steam used, and lowering energy consumption during in-mold molding. In contrast, beads obtained by directly pressing powder polymerized using conventional catalyst processes are too large and have irregular shapes, making in-mold molding impossible.

[0277] Among them, compared with the EPP beads made from polypropylene microparticles provided in Preparation Example 1, the polypropylene microparticles prepared in Preparation Examples 7 and 8 contained higher ash content, resulting in a significantly lower closed-cell rate in the EPP beads. Consequently, the performance of the molded body made from these EPP beads was lower than that of the molded body made from EPP beads EPP-A1. Furthermore, the polypropylene microparticles prepared in Preparation Example 9 had a large aspect ratio, and the EPP beads EPP-A9 made from them also had a large aspect ratio. Although this had little impact on other properties of the molded body, the shrinkage rate of the molded body was significantly increased.

[0278] The EPP beads prepared by this invention have a small particle size and high closed-cell rate, resulting in a smoother, more delicate surface of the molded body made from them. The shrinkage rate of the finished product is significantly reduced, leading to higher dimensional accuracy. At a similar apparent foaming ratio, the mechanical and thermal insulation properties are also superior to those of EPP molded bodies prepared using existing technologies.

[0279] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A type of polypropylene foamed beads, characterized in that, The polypropylene foam beads are obtained by foaming a foaming composition containing polypropylene microparticles. The average particle size of the polypropylene microparticles is ≤1mm, the aspect ratio of the polypropylene microparticles is ≤1.2, and the ash content of the polypropylene microparticles is ≤400ppm. The polypropylene microparticles were prepared according to the following method: In the presence of a catalyst, propylene-containing olefins undergo polymerization. The catalyst system comprises: a spherical support, a titanium halide compound, and an electron donor compound; The spherical carrier has the structure shown in formula (1): Equation (1) In equation (1), R1 is selected from C 1-10 Alkyl groups; R2 and R3 are each independently selected from H and C. 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 alkyl halogenates; R4 is selected from C atoms that are substituted with at least one halogen atom. 1-10 Halogenated alkyl groups and C groups substituted with at least one halogen atom 6-20 Halogenated aromatic groups; R5 is selected from C 1-5 Alkyl groups; X is selected from fluorine, chlorine, bromine, and iodine; m is 0.1-1.9, n is 0.1-1.9, and m+n=2; 0 <q<0.2;0<a<0.1。 2. The polypropylene foam beads according to claim 1, wherein, The average particle size of the polypropylene microparticles is ≤0.2 mm; And / or, the aspect ratio of the polypropylene microparticles is ≤1.15; And / or, the ash content of the polypropylene microparticles is ≤350ppm; And / or, the bulk density of the polypropylene microparticles is >0.35 g / cm³. 3 .

3. The polypropylene foamed beads according to claim 2, wherein, The bulk density of the polypropylene microparticles is >0.40 g / cm³. 3 .

4. The polypropylene foam beads according to claim 1, wherein, The particle size of the polypropylene foam beads is 0.03-3 mm; And / or, the aspect ratio of the polypropylene foam beads is 1-1.1:1; And / or, the ratio of the bulk expansion ratio to the apparent expansion ratio of the polypropylene foam beads is ≤1.6; And / or, the closed-cell rate of the polypropylene foam beads is ≥99%.

5. The polypropylene foam beads according to claim 1, wherein, The particle size of the polypropylene foam beads is 0.1-1 mm; And / or, the aspect ratio of the polypropylene foam beads is 1.01-1.05:1; And / or, the ratio of the bulk expansion ratio to the apparent expansion ratio of the polypropylene foam beads is ≤1.5; And / or, the closed-cell ratio of the polypropylene foam beads is ≥99.5%.

6. The polypropylene foam beads according to claim 1, wherein, The average particle diameter of the spherical carrier is 2-100 micrometers; the particle size distribution is less than 2.

7. The polypropylene foam beads according to claim 1, wherein, The average particle diameter of the spherical carrier is 2-19 micrometers; the particle size distribution is less than 0.6-1.

6.

8. The polypropylene foam beads according to claim 1, wherein, In equation (1), R1 is C 1-8 Alkyl groups; And / or, R2 and R3 are each independently selected from H, C 1-5 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-5 alkyl halogenates; And / or, R4 is selected from C atoms substituted with at least two halogen atoms. 1-10 Halogenated alkyl groups and C atoms substituted with at least two halogen atoms 6-20 Halogenated aromatic groups; And / or, R5 is selected from C 1-2 Alkyl groups; And / or, X is selected from chlorine and / or bromine.

9. The polypropylene foam beads according to claim 8, wherein, R1 is C 1-6 Alkyl groups.

10. The polypropylene foamed beads according to claim 1 or 2, wherein, The method for preparing the spherical carrier includes the following steps: (1) Component A is subjected to first contact and emulsification in sequence to obtain a first product, wherein component A contains magnesium halide with the general formula MgXY and a first alcohol compound with the general formula R1OH; (2) The first product is brought into a second contact with component B to obtain a second product, wherein component B contains an ethylene oxide compound having the structure shown in formula (2); (3) The second product is brought into a third contact with component C to obtain a third product, wherein component C contains a haloalcohol with the general formula R4OH and a second alcohol compound with the general formula R5OH; (4) Spray-dry the third product; Equation (2), In the formula R1OH, R1 is selected from C 1-10 Alkyl groups; In equation (2), R2 and R3 are each independently selected from H and C. 1-10 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-10 alkyl halogenates; In formula R4OH, R4 is chosen from C atoms substituted with at least one halogen atom. 1-10 Halogenated alkyl groups and C groups substituted with at least one halogen atom 6-20 Halogenated aromatic groups; In the formula R5OH, R5 is selected from C. 1-5 Alkyl groups; In the formula MgXY, X is selected from fluorine, chlorine, bromine, and iodine; Y is selected from fluorine, chlorine, bromine, iodine, and C. 1-6 alkyl, C 1-6 alkoxy, C 6-14 aryl and C 6-14 aryloxy groups; The amounts of component A, component B, and component C are such that the resulting spherical carrier has the structure shown in formula (1): Equation (1), In equation (1), m is 0.1-1.9, n is 0.1-1.9, and m+n=2; <q<0.2;0<a<0.1; In step (3), the amount of haloalcohol used is 0.05-6.5 mol relative to 1 mol of magnesium halide, and the amount of the second alcohol compound used is 5-100 mol.

11. The polypropylene foam beads according to claim 10, wherein, In the formula R1OH, R1 is selected from C. 1-8 Alkyl groups; And / or, in equation (2), R2 and R3 are each independently selected from H, C 1-5 Alkyl groups and C atoms substituted with 1-10 halogen atoms 1-5 alkyl halogenates; And / or, in formula R4OH, R4 is chosen from C atoms substituted with at least two halogen atoms. 1-10 Halogenated alkyl groups and C atoms substituted with at least two halogen atoms 6-20 Halogenated aromatic groups; And / or, in formula R5OH, R5 is selected from C. 1-2 Alkyl groups; And / or, in the formula MgXY, X is selected from chlorine and bromine; Y is selected from chlorine, bromine, and C. 1-5 alkyl, C 1-5 alkoxy, C 6-10 aryl and C 6-10 aryloxy groups.

12. The polypropylene foamed beads according to claim 10, wherein, The magnesium halide is selected from at least one of magnesium chloride, magnesium bromide, magnesium phenoxy chloride, magnesium isopropoxy chloride, and magnesium n-butoxy chloride; And / or, the first alcohol compound is selected from at least one of ethanol, n-propanol, isopropanol, n-butanol, isobutanol, n-pentanol, isopentanol, n-hexanol, n-octanol, and 2-ethylhexanol; And / or, the ethylene oxide compound is selected from at least one of ethylene oxide, propylene oxide, butane oxide, epichlorohydrin, chlorobutane, bromopropane, and bromobutane. And / or, the haloalcohol is selected from at least one of 2,2,2-trichloroethanol, 2,2-dichloroethanol, 1,2-dichloroethanol, 1,3-dichloropropanol, and 1,4-dichlorobutanol; And / or, relative to 1 mol of the magnesium halide, the amount of the first alcohol compound is 6-22 mol, the amount of the ethylene oxide compound is 2-6 mol, the amount of the haloalcohol is 1-5 mol, and the amount of the second alcohol compound is 8-80 mol.

13. The polypropylene foam beads according to claim 10, wherein, The first contact is carried out under stirring conditions, which include a temperature of 80-120°C and a time of 0.5-5 hours. And / or, the conditions for the second contact include: a temperature of 50-120°C and a time of 20-60 min; And / or, the conditions for spray drying include a temperature of 60-200°C.

14. The polypropylene foamed beads according to claim 13, wherein, The first contact is carried out under stirring conditions, which include a temperature of 80-100℃ and a time of 0.5-3h. And / or, the conditions for the second contact include: a temperature of 80-100°C and a time of 20-50 min; And / or, the conditions for spray drying include a temperature of 90-150°C.

15. The polypropylene foamed beads according to claim 1 or 2, wherein, The titanium halide compound is selected from at least one of titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, titanium tetra-n-butoxy, titanium tetraethoxy, titanium monochlorotri-n-butoxy, titanium dichlorodi-n-butoxy, titanium trichloro-n-butoxy, titanium monochlorotriethoxy, titanium dichlorodiethoxy, titanium trichloroethoxy, and titanium trichloride. And / or, the electron-donating compound is selected from at least one of diisobutyl phthalate, carboxylic acid diol ester, and phosphate ester.

16. A method for preparing polypropylene foamed beads according to any one of claims 1-15, characterized in that, The method includes foaming a foaming composition containing polypropylene microparticles in the presence of a foaming agent.

17. The method for preparing polypropylene foamed beads according to claim 16, wherein, The foaming temperature is 120-180℃, the foaming pressure is 0.5-16MPa, and the saturated impregnation time is 1-90min.

18. A polypropylene foamed bead molded body, characterized in that, The molded body is made from polypropylene foam beads as described in any one of claims 1-15.

19. The polypropylene foamed bead molded article according to claim 18, wherein, The shrinkage rate of the polypropylene foamed beads is ≤1.5%.

20. The polypropylene foamed bead molded body according to claim 19, wherein, The shrinkage rate of the polypropylene foamed beads is ≤1.2%.

21. A method for preparing polypropylene foamed beads according to any one of claims 18-20, characterized in that, In the presence of steam, the polypropylene foam beads according to any one of claims 1-15 are molded and cured to obtain the polypropylene foam bead molded body.

22. The method for preparing polypropylene foamed beads according to claim 21, wherein, The pressure of the steam is 1.3-1.8 kg; And / or, the molding conditions include: molding temperature of 110-130℃ and molding time of 5-20min; And / or, the curing conditions include: curing temperature of 80-120℃, curing time of 12-36h, and curing pressure of 1-1.1atm.

23. The application of the polypropylene foamed beads according to any one of claims 1-15 or the polypropylene foamed bead molded body according to any one of claims 18-20 in the production of autoclaved polypropylene foamed materials.

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