A foamed polypropylene base material, its preparation method and application

Abstract

The present invention provides a foamed polypropylene base material with excellent processing performance, melt index MFR [g·10min ‑1 , melt strength MS [N] at 200 °C, viscous flow activation energy E η [kJ·mol ‑1 at a shear rate ≥500 rpm, primary melting temperature [°C], flexural modulus FM [MPa], relative molecular weight distribution PD, and melt flow rate ratio FRR satisfy certain relational expressions. The foamed polypropylene base material prepared by the present invention has excellent comprehensive properties, such as a lower primary melting temperature, a wider melting range, a higher flexural modulus, etc. In addition, the present invention discloses a polymerization method for the foamed polypropylene, which is a binary or ternary copolymer base material synthesized from propylene, ethylene, and / or an α-olefin having 4-10 carbon atoms as raw materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of foamed polypropylene base materials, and relates to a foamed polypropylene base material, a preparation method thereof, and an application thereof. Background Art

[0002] Foamed polypropylene is a new type of material. It is a composite material formed by taking a polymer as a matrix and a large number of bubbles as fillers. In life, it is an essential material for modern production and life. However, general polypropylene (PP) has poor toughness, low melt strength, and poor foaming performance, making it difficult to prepare foamed materials by foaming ordinary PP, which limits its application in the fields of thermoforming and foaming. The reason is that PP has a long-chain structure and a tendency to crystallize, and its softening point and melting point are close, resulting in a narrow processing temperature window suitable for extrusion foaming. Below the melting point, the viscosity of the system is high and it is difficult to form pores. However, when the processing temperature is higher than the melting point of PP, the viscosity of PP is low, resulting in low melt strength, and the formed bubbles are difficult to be wrapped in the melt. At the same time, during the cooling stage, PP crystallizes with a large heat release and the viscosity of the system is relatively low, causing the formed bubbles to be further damaged.

[0003] Therefore, how to find a more suitable way to solve the above technical problems of the existing foamed polypropylene has become one of the problems that many front-line researchers in the industry urgently need to solve. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a foamed polypropylene base material, a preparation method thereof, and an application thereof, especially a foamed polypropylene base material. The foamed polypropylene base material provided by the present invention has a lower foaming temperature and a wider foaming temperature range.

[0005] The present invention provides a foamed polypropylene base material, and the melt strength MS [N] of the foamed polypropylene base material satisfies formula (1):

[0006] 13×MFR -4.29 ≤MS≤30×MFR -3 (1);

[0007] The viscous flow activation energy E η [kJ·mol -1 of the foamed polypropylene base material satisfies formula (2):

[0008] 1.0×MFR≤E η ≤1.8×MFR 1.43 (2);

[0009] Wherein, the melt index MFR of the foamed polypropylene base material is 5-10 g·10 min -1 ;

[0010] The flexural modulus FM [MPa] of the foamed polypropylene base material and the primary melting temperature satisfy Equation (3):

[0011] 4 × primary melting temperature ≤ FM ≤ 2 × primary melting temperature + 520 (3);

[0012] Among them, the primary melting temperature of the foamed polypropylene base material is 140 - 150 °C;

[0013] The melt flow rate ratio FRR of the foamed polypropylene base material and the relative molecular weight distribution PD satisfy Equation (4):

[0014] 1.6 × PD 1.53 ≤ FRR ≤ 2.0 × PD 2.1 (4);

[0015] Among them, the relative molecular weight distribution PD of the foamed polypropylene base material is 3.0 - 4.5.

[0016] Preferably, the melt strength is the melt strength at 200 °C;

[0017] The viscous flow activation energy is the viscous flow activation energy when the shear rate ≥ 500 rpm;

[0018] The melting range is 25 - 35 °C, and the primary melting temperature is 140 - 150 °C.

[0019] Preferably, the foamed polypropylene base material is foamed polypropylene pellets;

[0020] The foamed polypropylene base material is a base material for preparing polymers;

[0021] The preparation raw materials of the foamed polypropylene base material include foamed polypropylene powder and additives;

[0022] The additives include one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents.

[0023] Preferably, the foamed polypropylene powder includes polypropylene or a binary or ternary copolymer of propylene and one or more of ethylene and / or α-olefins having 4 - 10 carbon atoms;

[0024] The antioxidants include one or more of antioxidant 1010, antioxidant 3114, antioxidant 168, antioxidant DLTDP, and antioxidant DSTDP;

[0025] The plasticizers include one or more of calcium stearate, plasticizer DOP, plasticizer DBP, plasticizer DOS, and plasticizer TCP;

[0026] The fillers include one or more of talc powder, calcium carbonate, wollastonite, kaolin, and silica;

[0027] The nucleating agent includes one or more of nucleating agent 3988, nucleating agent NX8000, sodium benzoate, nucleating agent NA-21, and nucleating agent NA-11;

[0028] The antistatic agent includes one or more of antistatic agent GMS90, antistatic agent GMS60, antistatic agent ABPS, antistatic agent SN, and antistatic agent LDN.

[0029] Preferably, the mass content of the antioxidant in the foamed polypropylene base material is 0 to 2000 ppm;

[0030] The mass content of the plasticizer in the foamed polypropylene base material is 0 to 1000 ppm;

[0031] The mass content of the filler in the foamed polypropylene base material is 0 to 2000 ppm;

[0032] The mass content of the nucleating agent in the foamed polypropylene base material is 0 to 3000 ppm;

[0033] The mass content of the antistatic agent in the foamed polypropylene base material is 0 to 1000 ppm.

[0034] The present invention provides a method for preparing a foamed polypropylene base material, comprising the following steps:

[0035] 1) After carrying out a polymerization reaction on a monomer, a Ziegler-Natta catalyst, an alkylaluminum cocatalyst, an external electron donor, and hydrogen, a foamed polypropylene powder is obtained;

[0036] 2) After granulating the foamed polypropylene powder obtained in the above step and an additive, a foamed polypropylene base material is obtained.

[0037] Preferably, the polymerization includes bulk polymerization;

[0038] The monomer includes propylene;

[0039] The Ziegler-Natta catalyst includes a porous particulate or spherical catalyst containing a titanium compound with a magnesium halide as a carrier;

[0040] The alkylaluminum cocatalyst includes one or more of triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, and isobutyldichloroaluminum;

[0041] The external electron donor includes a silicon compound;

[0042] The temperature of the polymerization reaction is 0 to 150 °C.

[0043] Preferably, the monomer further includes propylene, and one or more of ethylene and / or an α-olefin having 4 to 10 carbon atoms;

[0044] The external electron donor includes one or more of cyclohexylmethyldimethoxysilane, cyclohexylmethyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, diisopropyldimethoxysilane, and phenyltrimethoxysilane;

[0045] The polymerization method includes direct polymerization or a two-stage polymerization method;

[0046] The temperature of the polymerization reaction is lower than the melting temperature of the copolymer.

[0047] The present invention provides an application of the foamed polypropylene base material described in any one of the above technical solutions or the foamed polypropylene base material prepared by the preparation method described in any one of the above technical solutions in the preparation of a polymer.

[0048] Preferably, the polymer includes a polymer for fields with lightweight requirements;

[0049] The fields with lightweight requirements include the packaging field.

[0050] The present invention provides a foamed polypropylene base material. Compared with the prior art, the present invention believes that to solve the above technical problems of the existing foamed polypropylene, it is necessary to adjust the structure and optimize the performance of PP, reduce its melting point, broaden its foaming temperature range, and improve its melt strength to meet the relevant requirements for foaming. Based on this, the present invention creatively designs a foamed polypropylene base material with specific properties. This foamed polypropylene base material has excellent processing performance, and its melt flow index MFR [g·10min -1 , melt strength MS [N] at 200 °C, viscous flow activation energy E η [kJ·mol -1 at a shear rate ≥ 500 rpm, primary melting temperature [°C], flexural modulus FM [MPa], relative molecular weight distribution PD, and melt flow rate ratio FRR satisfy certain relational expressions, and it has a lower foaming temperature and a wider foaming temperature range.

[0051] The foamed polypropylene base material provided by the present invention has excellent comprehensive properties, such as a lower primary melting temperature, a wider melting range, a higher flexural modulus, etc. In addition, the present invention discloses a polymerization method for this foamed polypropylene, which is a binary or ternary copolymer base material synthesized from propylene, ethylene, and / or an α-olefin having 4 to 10 carbon atoms. The foamed polypropylene base material provided by the present invention is more suitable for the packaging field or other fields with lightweight requirements. Detailed embodiments

[0052] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the invention.

[0053] There are no particular restrictions on the sources of all raw materials of the present invention, and they can be purchased on the market or prepared by conventional methods well-known to those skilled in the art.

[0054] There are no particular restrictions on the purity of all raw materials of the present invention. The present invention preferably uses analytical pure or the purity requirements conventional in the field of polypropylene foam material preparation.

[0055] All raw materials of the present invention, their grades and abbreviations belong to the conventional grades and abbreviations in the field. Each grade and abbreviation is clear and definite in the field of its related uses. Those skilled in the art can obtain them from the market or prepare them by conventional methods according to the grade, abbreviation and corresponding uses.

[0056] The present invention provides a polypropylene foam base material, and the melt strength MS [N] of the polypropylene foam base material satisfies formula (1):

[0057] 13×MFR -4.29 ≤MS≤30×MFR -3 (1);

[0058] The viscous flow activation energy E of the polypropylene foam base material η [kJ·mol -1 satisfies formula (2):

[0059] 1.0×MFR≤E η ≤1.8×MFR 1.43 (2);

[0060] wherein, the melt flow rate MFR of the polypropylene foam base material is 5-10 g·10 min -1 ;

[0061] The flexural modulus FM [MPa] of the polypropylene foam base material and the primary melting temperature satisfy formula (3):

[0062] 4×primary melting temperature≤FM≤2×primary melting temperature + 520 (3);

[0063] wherein, the primary melting temperature of the polypropylene foam base material is 140-150 °C;

[0064] The melt flow rate ratio FRR of the polypropylene foam base material and the relative molecular weight distribution PD satisfy formula (4):

[0065] 1.6×PD1.53 ≤FRR≤2.0×PD 2.1 (4);

[0066] Wherein, the relative molecular weight distribution PD of the foamed polypropylene base material is 3.0 to 4.5.

[0067] In the present invention, the melt flow index MFR of the foamed polypropylene base material is 5 to 10 g·10min -1 , and can be 6 to 9 g·10min -1 , preferably 7 to 8 g·10min -1 .

[0068] In the present invention, the primary melting temperature of the foamed polypropylene base material is 140 to 150 °C, can be 142.5 to 148.5 °C, and preferably 143 to 147 °C.

[0069] In the present invention, the relative molecular weight distribution PD of the foamed polypropylene base material is 3.0 to 4.5, can be 3.2 to 4.3, and preferably 3.4 to 4.0.

[0070] In order to complete and refine the overall technical solution of the present invention, better ensure the composition and properties of the foamed polypropylene base material, and further improve the polymerization performance of the foamed polypropylene base material, the above-mentioned foamed polypropylene base material specifically may include the following:

[0071] A foamed polypropylene base material, the melt flow index MFR of the polypropylene base material is 5 - 10 g·10min -1 , the melt strength MS [N] at 200 °C, and the viscous flow activation energy E η [kJ·mol -1 and the melt flow index satisfy the following formulas (1) and (2); the primary melting temperature is 140 - 150 °C, the flexural modulus FM [MPa] and the primary melting temperature satisfy the following formula (3); the relative molecular weight distribution PD is 3 - 4.5, and the melt flow rate ratio FRR and the relative molecular weight distribution PD satisfy the following formula (4).

[0072] 13×MFR -4.29 ≤MS≤30×MFR -3 (1)

[0073] 1.0×MFR≤E η ≤1.8×MFR 1.43 (2)

[0074] 4×primary melting temperature≤FM≤2×primary melting temperature + 520 (3)

[0075] 1.6×PD 1.53 ≤FRR≤2.0×PD2.1 (4).

[0076] Specifically, its melt flow index MFR is measured under a load of 2.16 kg and a test temperature of 230 °C, and the melt flow index is preferably 5-10 g·10 min -1 .

[0077] Specifically, its primary melting temperature is measured by a differential scanning calorimeter, and the obtained DSC curve is processed to obtain a primary melting temperature of 140-150 °C and a melting range of 25-35 °C (end melting temperature - start melting temperature).

[0078] Specifically, its relative molecular weight distribution PD is measured by gel permeation chromatography. Using trichlorobenzene as the solvent, the obtained relative molecular weight distribution PD is 3-4.5.

[0079] Furthermore:

[0080] The foamed polypropylene base material provided by the present invention has a melt flow index MFR of 5-10 g·10 min -1 , the melt strength MS [N] at 200 °C, and the viscous flow activation energy E η [kJ·mol -1 and the melt flow index satisfy the following formulas (1) and (2); the primary melting temperature is 140-150 °C, the flexural modulus FM [MPa] and the primary melting temperature satisfy the following formula (3); the relative molecular weight distribution PD is 3-4.5, and the melt flow rate ratio FRR and the relative molecular weight distribution PD satisfy the following formula (4).

[0081] 13×MFR -4.29 ≤MS≤30×MFR -3 (1)

[0082] 1.0×MFR≤E η ≤1.8×MFR 1.43 (2)

[0083] 4×primary melting temperature≤FM≤2×primary melting temperature + 520 (3)

[0084] 1.6×PD 1.53 ≤FRR≤2.0×PD 2.1 (4).

[0085] The melt flow rate MFR of the foamed polypropylene base material of the present invention is usually 5-10 g·10 min -1 , more preferably 7-8 g·10 min -1 , and this melt flow rate is measured according to the method described in GB / T 3682.1-2018 under a load of 2.16 kg and a test temperature of 230 °C.

[0086] The melt strength MS [N] of the foamed polypropylene base material of the present invention at 200 °C and its melt flow rate MFR satisfy the relationship of formula (1).

[0087] 13 × MFR -4.29 ≤ MS ≤ 30 × MFR -3 (1)

[0088] The foamed polypropylene base material of the present invention has good foaming properties. When the relationship of MS ≥ 13 × MFR in formula (1) is not satisfied, that is, when the melt strength is too low, it is difficult to maintain the cell morphology during foaming processing, resulting in cell collapse, coalescence and cell stringing phenomena. And when the relationship of MS ≤ 30 × MFR in formula (1) is not satisfied, that is, when the melt strength is too high, the bubble growth is too slow during the foaming process. -4.29 When the relationship of MS ≤ 30 × MFR in formula (1) is not satisfied, that is, when the melt strength is too high, the bubble growth is too slow during the foaming process. -3 When the relationship of MS ≤ 30 × MFR in formula (1) is not satisfied, that is, when the melt strength is too high, the bubble growth is too slow during the foaming process.

[0089] The preferred relationship satisfied by the foamed polypropylene base material of the present invention is: 15 × MFR -4.29 ≤ MS ≤ 28 × MFR -3 ,

[0090] More preferably: 17 × MFR -4.29 ≤ MS ≤ 26 × MFR -3 .

[0091] The melt strength MS in the above formula (1) is measured using a capillary rheometer. The test parameters are as follows: the die diameter of the instrument is 2 mm, the length is 20 mm, the test temperature is 200 °C, and the initial extrusion stretching speed is 5 mm·min -1 , and the rotation speed reaches 80 m·min at a certain acceleration -1 , and the scanning time is 12 min. The melt of the foamed polypropylene base material is uniaxially stretched, and the force received during stretching is the uniform acceleration rotation of the traction roller until the melt bundle breaks. At this time, the force received is the melt strength in formula (1).

[0092] The viscous flow activation energy E of the foamed polypropylene base material of the present invention η [kJ·mol -1 and its melt flow rate MFR satisfy the relationship of formula (2).

[0093] 1.0 × MFR ≤ E η ≤ 1.8 × MFR 1.43 (2).

[0094] The molecular chain of the foamed polypropylene base material of the present invention has good flexibility, and when the processing shear speed ≥ 500 rpm, when E in formula (2) ηWhen the relationship of ≥ 1.0 × MFR is not satisfied, that is, when the viscous flow activation energy is too small, it indicates that the entanglement degree of molecular chains is too low, which will cause the cell morphology to be unable to be maintained during the foaming process; when E η ≤ 1.8 × MFR 1.43 is not satisfied, that is, when the viscous flow activation energy is too large, it indicates that the entanglement degree of molecular chains is too high, which will cause the cells to be difficult to form or grow slowly during the foaming process; then when the shear rate is relatively high (≥ 500 rpm) and the viscous flow activation energy is moderate, it is beneficial to its foaming processing.

[0095] The relational expression satisfied by the foamed polypropylene base material of the present invention is preferably: 1.05 × MFR ≤ E η ≤ 1.75 × MFR 1.43 ,

[0096] More preferably: 1.1 × MFR ≤ E η ≤ 1.7 × MFR 1.43 .

[0097] By using the Arrhenius equation η = Aexp(E η / RT), taking the logarithm of both sides of the above formula gives the formula: lnη = lnA + (E η / RT), where η - shear viscosity [Pa·s], A - pre-exponential factor, R - molar gas constant [8.314 J·(mol·K) -1 , T - thermodynamic temperature [K], plotting lnη against 1 / T, the viscous flow activation energy E η [kJ·mol -1 data in the above formula (2) can be obtained from the slope of the resulting straight line.

[0098] Among them, the shear viscosity η is measured using a capillary rheometer. The foamed polypropylene base material is melted by electric heating in the barrel. A capillary die (diameter 1 mm, length 16 mm) is installed at the lower part of the barrel. After the temperature is stabilized, the plunger at the upper part of the barrel drives the material to be extruded from the die of the capillary at a certain speed under the drive of the driving motor. During the extrusion process, the shear viscosity of the melt can be calculated through various parameters.

[0099] The melt flow rate MFR in formula (2) is the same as the melt flow rate MFR in formula (1).

[0100] The primary melting temperature of the foamed polypropylene base material of the present invention is usually 140 - 150 °C, preferably 142.5 - 148.5 °C, more preferably 143 - 147 °C. This primary melting temperature is measured using a differential scanning calorimeter according to the method described in GB / T 1946.6 - 2009, and the obtained DSC curve is processed. By the same method, the melting range of the foamed polypropylene base material is 25 - 35 °C (termination melting temperature - starting melting temperature).

[0101] The flexural modulus FM [MPa] of the foamed polypropylene base material of the present invention and its primary melting temperature satisfy the relationship of formula (3),

[0102] 4 × primary melting temperature ≤ FM ≤ 2 × primary melting temperature + 520 (3).

[0103] The foamed polypropylene base material of the present invention has good foaming processability. When the relationship of FM ≥ 4 × primary melting temperature in formula (3) is not satisfied, that is, when the flexural modulus is too low, the overall rigidity of the product after foaming processing cannot be guaranteed. When the relationship of FM ≤ 2 × primary melting temperature + 520 in formula (3) is not satisfied, that is, when the flexural modulus is too high, the bubble growth during the foaming process is too slow or even no foaming can occur.

[0104] The relational expression satisfied by the foamed polypropylene base material of the present invention is preferably:

[0105] 4 × primary melting temperature + 25 ≤ FM ≤ 2 × primary melting temperature + 495,

[0106] More preferably:

[0107] 4 × primary melting temperature + 50 ≤ FM ≤ 2 × primary melting temperature + 470.

[0108] The flexural modulus in the above formula (3) is measured according to the method described in GB / T 9341 - 2008. Using a universal testing tensile machine, the specific testing method is the three - point loading test method, that is, the standard specimen is supported as a crossbeam, and it is bent at a constant speed (2 mm·min -1 ) at the center of the span (64 mm) until the specimen breaks or the deformation reaches a predetermined value (6 mm), and the pressure applied to the specimen during this process is measured. The ratio of the stress difference to the corresponding strain difference is the flexural modulus in formula (3), in units of MPa.

[0109] The relative molecular mass distribution PD of the foamed polypropylene base material of the present invention is usually 3.0 - 4.5, more preferably 3.4 - 4.0, and this relative molecular mass distribution PD is measured by gel permeation chromatography with trichlorobenzene as the solvent.

[0110] The melt flow rate ratio FRR of the foamed polypropylene base material of the present invention and its relative molecular mass distribution PD satisfy the relationship of formula (4),

[0111] 1.6 × PD 1.53 ≤ FRR ≤ 2.0 × PD 2.1 (4).

[0112] When the foamed polypropylene base material of the present invention satisfies formula (4), the relative molecular mass distribution is moderate, the processing rheological properties during processing the product are good, and the toughness and strength of its product are better.

[0113] The foamed polypropylene base material of the present invention preferably satisfies the relational expression: 1.65×PD 1.53 ≤FRR≤1.95×PD 2.1

[0114] More preferably: 1.7×PD 1.53 ≤FRR≤1.9×PD 2.1 。

[0115] The melt flow rate ratio FRR in the above formula (4) is the value obtained by dividing the melt index measured at 230 °C under a load of 10 kg by the melt index measured under a load of 2.16 kg according to GB / T 3682.1-2018.

[0116] The foamed polypropylene base material of the present invention is a copolymer, a binary or ternary copolymer containing repeating units of propylene, ethylene and / or repeating units of α-olefins having 4 to 10 carbon atoms.

[0117] The α-olefins having 4 to 10 carbon atoms include 1-butene, 4-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-nonene, 1-decene, etc., and preferably 1-butene.

[0118] The content of the repeating unit of propylene is 85 to 98% based on the total weight (100 wt%) of the copolymer of propylene, ethylene and / or α-olefins having 4 to 10 carbon atoms, the content of the repeating unit of ethylene is 0 to 5% based on the total weight (100 wt%) of the copolymer of propylene, ethylene and / or α-olefins having 4 to 10 carbon atoms, and the content of the repeating unit of α-olefins having 4 to 10 carbon atoms is 0 to 10% based on the total weight (100 wt%) of the copolymer of propylene, ethylene and / or α-olefins having 4 to 10 carbon atoms.

[0119] The copolymer of propylene, ethylene and / or α-olefin of the present invention is preferably an α-olefin having 4 to 8 carbon atoms, more preferably an α-olefin having 4 to 6 carbon atoms. Among various copolymers of propylene, ethylene and / or α-olefins having 4 to 6 carbon atoms, propylene-ethylene or propylene-1-butene or propylene-ethylene-1-butene copolymers are preferred.

[0120] In the present invention, the foamed polypropylene base material is preferably foamed polypropylene pellets.

[0121] In the present invention, the foamed polypropylene base material is preferably a base material for preparing polymers.

[0122] In the present invention, the raw materials for preparing the foamed polypropylene base material preferably include foamed polypropylene powder and additives. Among them, the additives preferably include one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents, and more preferably include multiple ones among antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents.

[0123] In the present invention, the foamed polypropylene powder preferably includes polypropylene or a binary or ternary copolymer of propylene and one or more of ethylene and / or an α-olefin having 4 to 10 carbon atoms, more preferably polypropylene or a binary or ternary copolymer of propylene and one or more of ethylene or an α-olefin having 6 to 9 carbon atoms, more preferably polypropylene or a binary or ternary copolymer of propylene and one or more of ethylene or an α-olefin having 7 to 8 carbon atoms, and more preferably a binary or ternary copolymer of propylene and one or more of ethylene and / or an α-olefin having 4 to 10 carbon atoms.

[0124] In the present invention, the antioxidant preferably includes one or more of antioxidant 1010, antioxidant 3114, antioxidant 168, antioxidant DLTDP, and antioxidant DSTDP, and more preferably antioxidant 1010, antioxidant 3114, antioxidant 168, antioxidant DLTDP, or antioxidant DSTDP.

[0125] In the present invention, the plasticizer preferably includes one or more of calcium stearate, plasticizer DOP, plasticizer DBP, plasticizer DOS, and plasticizer TCP, and more preferably calcium stearate, plasticizer DOP, plasticizer DBP, plasticizer DOS, or plasticizer TCP.

[0126] In the present invention, the filler preferably includes one or more of talc powder, calcium carbonate, wollastonite, kaolin, and silica, and more preferably talc powder, calcium carbonate, wollastonite, kaolin, or silica.

[0127] In the present invention, the nucleating agent preferably includes one or more of nucleating agent 3988, nucleating agent NX8000, sodium benzoate, nucleating agent NA-21, and nucleating agent NA-11, and more preferably nucleating agent 3988, nucleating agent NX8000, sodium benzoate, nucleating agent NA-21, or nucleating agent NA-11.

[0128] In the present invention, the antistatic agent preferably includes one or more of antistatic agent GMS90, antistatic agent GMS60, antistatic agent ABPS, antistatic agent SN, and antistatic agent LDN, and more preferably antistatic agent GMS90, antistatic agent GMS60, antistatic agent ABPS, antistatic agent SN, or antistatic agent LDN.

[0129] In the present invention, the mass content of the antioxidant in the foamed polypropylene base material is preferably 0 to 2000 ppm, more preferably 10 to 1800 ppm, and even more preferably 100 to 1600 ppm.

[0130] In the present invention, the mass content of the plasticizer in the foamed polypropylene base material is preferably 0 to 1000 ppm, more preferably 10 to 900 ppm, and even more preferably 50 to 800 ppm.

[0131] In the present invention, the mass content of the filler in the foamed polypropylene base material is preferably 0 to 2000 ppm, more preferably 10 to 1800 ppm, and even more preferably 100 to 1600 ppm.

[0132] In the present invention, the mass content of the nucleating agent in the foamed polypropylene base material is preferably 0 to 3000 ppm, more preferably 100 to 2750 ppm, and even more preferably 500 to 2500 ppm.

[0133] In the present invention, the mass content of the antistatic agent in the foamed polypropylene base material is preferably 0 to 1000 ppm, more preferably 10 to 900 ppm, and even more preferably 50 to 800 ppm.

[0134] The present invention provides a method for preparing a foamed polypropylene base material, comprising the following steps:

[0135] 1) subjecting a monomer, a Ziegler-Natta catalyst, an alkyl aluminum co-catalyst, an external electron donor, and hydrogen to a polymerization reaction to obtain a foamed polypropylene powder;

[0136] 2) The foamed polypropylene powder and additives obtained in the above steps are granulated to obtain a foamed polypropylene base material.

[0137] The invention firstly carries out polymerization reaction on monomers, Ziegler-Natta catalyst, alkyl aluminum co-catalyst, external electron donor and hydrogen to obtain foamed polypropylene powder.

[0138] In the present invention, the polymerization preferably includes bulk polymerization.

[0139] In the present invention, the monomer preferably includes propylene.

[0140] In the present invention, the Ziegler-Natta catalyst preferably comprises a porous granular or spherical catalyst containing a titanium compound and using a magnesium halide as a carrier.

[0141] In the present invention, the alkylaluminum cocatalyst preferably includes one or more of triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, and isobutyldichloroaluminum, and more preferably is triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, or isobutyldichloroaluminum.

[0142] In the present invention, the external electron donor preferably includes a silicon compound.

[0143] In the present invention, the temperature of the polymerization reaction is preferably 0 to 150 °C, more preferably 30 to 120 °C, and even more preferably 60 to 90 °C.

[0144] In the present invention, the monomer further preferably includes propylene, and one or more of ethylene and / or an α-olefin having 4 to 10 carbon atoms, more preferably propylene, and ethylene or an α-olefin having 6 to 9 carbon atoms, and even more preferably propylene, and ethylene or an α-olefin having 7 to 8 carbon atoms.

[0145] In the present invention, the external electron donor preferably includes one or more of cyclohexylmethyldimethoxysilane, cyclohexylmethyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, diisopropyldimethoxysilane, and phenyltrimethoxysilane, and more preferably is cyclohexylmethyldimethoxysilane, cyclohexylmethyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, diisopropyldimethoxysilane, or phenyltrimethoxysilane.

[0146] In the present invention, the polymerization method preferably includes direct polymerization or a two-stage polymerization method.

[0147] In the present invention, the temperature of the polymerization reaction is preferably less than the melting temperature of the copolymer. Among them, the melting temperature of the copolymer in the present invention refers to the melting temperature of the foamed polypropylene powder.

[0148] Finally, in the present invention, the foamed polypropylene powder and the additive obtained in the above steps are granulated to obtain a foamed polypropylene base material.

[0149] To complete and refine the overall technical solution of the present invention, better ensure the composition and properties of the foamed polypropylene base material, and further improve the polymerization performance of the foamed polypropylene base material, the preparation method of the above-mentioned foamed polypropylene base material may specifically include the following content:

[0150] A foamed polypropylene base material, the melt flow index MFR of the polypropylene base material is 5 to 10 g·10 min -1 , the melt strength MS [N] at 200 °C, and the viscous flow activation energy E η [kJ·mol -1satisfies the following formulas (1) and (2); the primary melting temperature is 140 - 150 °C, the flexural modulus FM [MPa] and the primary melting temperature satisfy the following formula (3); the relative molecular weight distribution PD is 3.0 - 4.5, and the melt flow rate ratio FRR and the relative molecular weight distribution PD satisfy the following formula (4).

[0151] 13×MFR -4.29 ≤MS≤30×MFR -3 (1)

[0152] 1.0×MFR≤E η ≤1.8×MFR 1.43 (2)

[0153] 4×primary melting temperature≤FM≤2×primary melting temperature + 520 (3)

[0154] 1.6×PD 1.53 ≤FRR≤2.0×PD 2.1 (4).

[0155] The preparation method is to add monomers, Ziegler - Natta catalyst, alkyl aluminum cocatalyst, external electron donor and hydrogen into a polymerization reactor, and carry out polymer synthesis at a certain temperature by bulk polymerization process. After the reaction is completed, unreacted monomers and hydrogen are removed under reduced pressure to obtain foamed polypropylene powder; after adding various additives, the powder is granulated using a twin - screw extruder to obtain foamed polypropylene base material.

[0156] Specifically, the polymerization reactor is any one of a stainless - steel pressure - resistant reaction kettle with a temperature - controlled jacket and a mechanical stirring device, a tubular reactor or a stirred - tank reactor.

[0157] Specifically, the monomers are propylene, ethylene and / or α - olefins with 4 - 10 carbon atoms.

[0158] Specifically, the Ziegler - Natta catalyst is a porous particulate or spherical catalyst containing a titanium compound with a magnesium halide as the carrier; the titanium compound is selected from any one of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide; the magnesium halide is selected from any one of magnesium dichloride, magnesium dibromide, and magnesium diiodide.

[0159] Specifically, the alkyl aluminum cocatalyst is an aluminum compound; the aluminum compound is selected from any one or more of triisobutyl aluminum, triethyl aluminum, dimethyl aluminum chloride, diethyl aluminum chloride, and isobutyl aluminum dichloride.

[0160] Specifically, the external electron donor is a silicon compound; the silicon compound is selected from any one or more of cyclohexylmethyl dimethoxysilane, cyclohexylmethyl trimethoxysilane, dicyclopentyl dimethoxysilane, dicyclohexyl dimethoxysilane, diisopropyl dimethoxysilane, and phenyltrimethoxysilane.

[0161] Specifically, the bulk polymerization process is used for direct polymerization or two-stage polymerization.

[0162] Specifically, the polymerization reaction temperature should be lower than the melting temperature of the copolymer, and the temperature range is 0 to 150 °C.

[0163] Specifically, the foamed polypropylene base material is a mixture, and the mixture contains additives; the additives are selected from any one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents.

[0164] More specifically:

[0165] The preparation method of the foamed polypropylene base material of the present invention is to add monomers, Ziegler-Natta catalysts, alkylaluminum cocatalysts, external electron donors, and hydrogen into a polymerization reactor, and carry out polymer synthesis by using a bulk polymerization process. After the reaction is completed, unreacted monomers and hydrogen are removed under reduced pressure to obtain foamed polypropylene powder. After adding various additives, a twin-screw extruder is used for powder granulation to obtain the foamed polypropylene base material.

[0166] Preferably, the polymerization reactor is any one of a stainless steel pressure-resistant reaction kettle with a temperature control jacket and a mechanical stirring device, a tubular reactor, or a stirred tank reactor; preferably, the reactor is a kettle reactor.

[0167] Further, the monomers are propylene, ethylene, and / or α-olefins having 4 to 10 carbon atoms.

[0168] Further, the Ziegler-Natta catalyst is a porous particulate or spherical catalyst containing a titanium compound with a magnesium halide as a carrier; the titanium compound is selected from any one of titanium tetrachloride, titanium tetrabromide, and titanium tetraiodide; the magnesium halide is selected from any one of magnesium dichloride, magnesium dibromide, and magnesium diiodide.

[0169] Further, the alkylaluminum cocatalyst is an aluminum compound; the aluminum compound is selected from any one or more of triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, and isobutyldichloroaluminum.

[0170] Further, the external donor is a silicon compound; the silicon compound is selected from any one or more of cyclohexylmethyldimethoxysilane, cyclohexylmethyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, diisopropyldimethoxysilane, and phenyltrimethoxysilane.

[0171] Further, a direct copolymerization or two-stage polymerization method of a bulk polymerization process is adopted. The two-stage polymerization divides the polymerization process into two stages. The first-stage reaction is carried out at a lower temperature, and the conversion rate is controlled at a lower level (10-30%). At this time, the system viscosity is low, heat dissipation is easy, and there is no sticking to the kettle; the second-stage reaction gradually raises the temperature to improve the conversion efficiency. Therefore, the two-stage polymerization method is preferably used.

[0172] Further, the polymerization reaction temperature should be lower than the melting temperature of the copolymer, and the temperature range is 0-150 °C, more preferably 20-80 °C.

[0173] Further, the foamed polypropylene base material is a mixture, and the mixture contains additives; the additives are selected from any one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents.

[0174] The present invention also provides the use of the foamed polypropylene base material described in any one of the above technical solutions or the foamed polypropylene base material prepared by the preparation method described in any one of the above technical solutions in the preparation of polymers.

[0175] In the present invention, the polymer preferably includes polymers for fields with lightweight requirements.

[0176] In the present invention, the fields with lightweight requirements preferably include the packaging field.

[0177] Specifically, the foamed polypropylene base material and the foamed polypropylene base material obtained by the preparation method described in the above technical solution are applied to the packaging field or other fields with lightweight requirements.

[0178] The above content of the present invention provides a foamed polypropylene base material, its preparation method, and application. The present invention designs a foamed polypropylene base material with specific properties. This foamed polypropylene base material has excellent processing performance, and its melt index MFR [g·10min -1 , melt strength MS [N] at 200 °C, viscous flow activation energy E η [kJ·mol -1 , primary melting temperature [°C], flexural modulus FM [MPa], relative molecular weight distribution PD, and melt flow rate ratio FRR satisfy certain relationships, and it has a lower foaming temperature and a wider foaming temperature range.

[0179] The foamed polypropylene base material provided by the present invention has excellent comprehensive properties, such as a relatively low primary melting temperature, a relatively wide melting range, a relatively high flexural modulus, etc. In addition, the present invention discloses a polymerization method for the foamed polypropylene, and the method is a binary or ternary copolymer base material synthesized from propylene, ethylene, and / or an α-olefin having 4 to 10 carbon atoms as raw materials. The foamed polypropylene base material provided by the present invention is more suitable for the packaging field or other fields with lightweight requirements.

[0180] In order to further illustrate the present invention, the following is a detailed description of a foamed polypropylene base material provided by the present invention, its preparation method, and its application in combination with embodiments. However, it should be understood that these embodiments are implemented on the premise of the technical solution of the present invention, and detailed implementation manners and specific operation processes are given, only to further illustrate the features and advantages of the present invention, rather than a limitation on the claims of the present invention. The protection scope of the present invention is not limited to the following embodiments.

[0181] Example 1

[0182] Sufficient liquid-phase propylene and 1-butene were refined through a refining system respectively. A 10L jacketed stainless-steel pressure polymerization kettle with mechanical stirring was heated to 60 °C. After being replaced with high-purity nitrogen and evacuated, it was cooled to 25 °C for standby. First-stage reaction: 0.65 kg of propylene monomer, 0.15 kg of 1-butene monomer, 0.21 g of catalyst, 6 mL of triethylaluminum, 0.44 mL of external electron donor, and 4.5 L of hydrogen were successively added into the reaction kettle. The reaction kettle was heated to 40 °C and kept at a constant temperature for 20 min. After the first-stage reaction ended, the pressure in the kettle was completely emptied, and the temperature in the kettle was lowered to 25 °C to prepare for the second-stage reaction. Second-stage reaction: 1.02 kg of propylene monomer (the total proportion of propylene feed in the two-stage reaction is 83.5%) and 0.18 kg of 1-butene monomer (the total proportion of 1-butene feed in the two-stage reaction is 16.5%), 7 mL of triethylaluminum, and 5.5 L of hydrogen were added into the reaction kettle again. The reaction kettle was heated to 60 °C and kept at a constant temperature for 40 min. After the second-stage reaction was completed, the pressure in the kettle was emptied, and it was replaced with high-purity nitrogen 3 times. The reaction kettle was cooled to room temperature. A variety of additives were added to the obtained propylene-1-butene copolymer powder, and then it was extruded and pelletized. The pellets were injection-molded into standard specimens. The physical property evaluation results of the obtained copolymer are shown in Table 1, and Table 1 is the physical property evaluation results of the copolymers prepared in the examples and comparative examples of the present invention.

[0183] Table 1

[0184]

[0185]

[0186] Example 2

[0187] Refine sufficient liquid-phase propylene and gaseous ethylene separately through the refining system. Heat a 10L jacketed stainless steel pressure polymerization kettle with mechanical stirring to 60°C. After purging with high-purity nitrogen and vacuum treatment, cool it to 25°C for standby. For the first-stage reaction, sequentially add 0.77 kg of propylene monomer, 0.03 kg of ethylene monomer, 0.21 g of catalyst, 6 mL of triethylaluminum, 0.44 mL of external electron donor, and 4.5 L of hydrogen into the reaction kettle. Heat the reaction kettle to 40°C and keep it at a constant temperature for 20 min. After the first-stage reaction is completed, evacuate all the pressure in the kettle, and cool the temperature in the kettle to 25°C to prepare for the second-stage reaction. For the second-stage reaction, add 1.16 kg of propylene monomer (the total proportion of propylene feed in the two-stage reaction is 96.5%), 0.04 kg of ethylene monomer (the total proportion of ethylene feed in the two-stage reaction is 3.5%), 7 mL of triethylaluminum, and 5.5 L of hydrogen into the reaction kettle again. Heat the reaction kettle to 60°C and keep it at a constant temperature for 40 min. After the second-stage reaction is completed, evacuate the pressure in the kettle, and replace it with high-purity nitrogen 3 times. Cool the reaction kettle to room temperature. Add various additives to the taken-out propylene-ethylene copolymer powder and then extrude and pelletize it. Inject the pellets into standard specimens. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0188] Example 3

[0189] Refine sufficient liquid-phase propylene, gaseous ethylene, and liquid-phase 1-butene separately through the refining system. Heat a 10L jacketed stainless steel pressure polymerization kettle with mechanical stirring to 60°C. After purging with high-purity nitrogen and vacuum treatment, cool it to 25°C for standby. For the first-stage reaction, sequentially add 0.67 kg of propylene monomer, 0.02 kg of ethylene monomer, 0.11 kg of 1-butene monomer, 0.21 g of catalyst, 6 mL of triethylaluminum, 0.44 mL of external electron donor, and 4.5 L of hydrogen into the reaction kettle. Heat the reaction kettle to 40°C and keep it at a constant temperature for 20 min. After the first-stage reaction is completed, evacuate all the pressure in the kettle, and cool the temperature in the kettle to 25°C to prepare for the second-stage reaction. For the second-stage reaction, add 1.04 kg of propylene monomer (the total proportion of propylene feed in the two-stage reaction is 85.5%), 0.03 kg of ethylene monomer (the total proportion of ethylene feed in the two-stage reaction is 2.5%), 0.13 kg of 1-butene monomer (the total proportion of 1-butene feed in the two-stage reaction is 12%), 7 mL of triethylaluminum, and 5.5 L of hydrogen into the reaction kettle again. Heat the reaction kettle to 60°C and keep it at a constant temperature for 40 min. After the second-stage reaction is completed, evacuate the pressure in the kettle, and replace it with high-purity nitrogen 3 times. Cool the reaction kettle to room temperature. Add various additives to the taken-out propylene-ethylene-1-butene copolymer powder and then extrude and pelletize it. Inject the pellets into standard specimens. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0190] Comparative Example 1

[0191] Refine sufficient liquid-phase propylene and 1-butene respectively through a refining system. Heat a 10L jacketed stainless-steel pressure polymerization kettle with mechanical stirring to 60°C. After replacement with high-purity nitrogen and evacuation, cool it to 25°C for standby. For the first-stage reaction, add 0.64 kg of propylene monomer, 0.16 kg of 1-butene monomer, a catalyst system, and 1.5 L of hydrogen into the reaction kettle in sequence. Heat the reaction kettle to 40°C and keep the temperature constant for 20 min. After the first-stage reaction ends, evacuate all the pressure in the kettle, and cool the temperature in the kettle to 25°C to prepare for the second-stage reaction. For the second-stage reaction, add 0.96 kg of propylene monomer (the total proportion of propylene feed in the two-stage reaction is 80%), 0.24 kg of 1-butene monomer (the total proportion of 1-butene feed in the two-stage reaction is 20%), a catalyst system, and 2.5 L of hydrogen into the reaction kettle again. Heat the reaction kettle to 60°C and keep the temperature constant for 40 min. After the second-stage reaction is completed, evacuate the pressure in the kettle, and replace it with high-purity nitrogen 3 times. Cool the reaction kettle to room temperature. Add various additives to the taken-out propylene-1-butene copolymer powder and then extrude and pelletize it. Inject the pellets into standard splines. The physical property evaluation results of the obtained copolymer are shown in Table 1.

[0192] The above has introduced in detail a foamed polypropylene base material, its preparation method, and its application provided by the present invention. Specific examples are used herein to elaborate on the principle and implementation mode of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those of ordinary skill in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention. The protection scope of the present invention patent is defined by the claims and may include other embodiments that can be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the literal description of the claims, or if they include equivalent structural elements that have no substantial difference from the literal description of the claims, then these other embodiments should also be included within the scope of the claims.

Claims

1. Application of foamed polypropylene base material in preparing polymers; The polymer is a polymer used in fields with lightweight requirements; The melt strength MS [N] of the foamed polypropylene base material satisfies formula (1): 13 × MFR -4.29 ≤ MS ≤ 30 × MFR -3 (1); The viscous flow activation energy E of the foamed polypropylene base material η [kJ·mol -1 satisfies Equation (2): 1.0×MFR ≤ E η ≤ 1.8×MFR 1.43 (2); Among them, The melt flow index MFR of the foamed polypropylene base material is 5 to 10 g·10 min -1 ; The flexural modulus FM [MPa] of the foamed polypropylene base material and the primary melting temperature satisfy formula (3): 4 × primary melting temperature ≤ FM ≤ 2 × primary melting temperature + 520 (3); Among them, the primary melting temperature of the foamed polypropylene base material is 140 - 150 °C; The melt flow rate ratio FRR and the relative molecular weight distribution PD of the foamed polypropylene base material satisfy formula (4): 1.6×PD 1.53 ≤FRR≤2.0×PD 2.1 (4); Among them, the relative molecular weight distribution PD of the foamed polypropylene base material is 3.0 - 4.

5.

2. The application according to claim 1, characterized in that, The melt strength is the melt strength at 200 °C; The viscous flow activation energy is the viscous flow activation energy when the shear rate ≥ 500 rpm; The melting range is 25 - 35 °C, and the primary melting temperature is 140 - 150 °C.

3. The application according to claim 1, characterized in that, The foamed polypropylene base material is foamed polypropylene pellets; The foamed polypropylene base material is a base material for preparing polymers; The preparation raw materials of the foamed polypropylene base material include foamed polypropylene powder and additives; The additives include one or more of antioxidants, plasticizers, fillers, nucleating agents, and antistatic agents.

4. The application according to claim 3, wherein The foamed polypropylene powder includes polypropylene or a binary or ternary copolymer of propylene with one or more of ethylene and / or α-olefins having 4 - 10 carbon atoms; The antioxidants include one or more of antioxidant 1010, antioxidant 3114, antioxidant 168, antioxidant DLTDP, and antioxidant DSTDP; The plasticizers include one or more of calcium stearate, plasticizer DOP, plasticizer DBP, plasticizer DOS, and plasticizer TCP; The fillers include one or more of talc powder, calcium carbonate, wollastonite, kaolin, and silica; The nucleating agents include one or more of nucleating agent 3988, nucleating agent NX8000, sodium benzoate, nucleating agent NA-21, and nucleating agent NA-11; The antistatic agents include one or more of antistatic agent GMS90, antistatic agent GMS60, antistatic agent ABPS, antistatic agent SN, and antistatic agent LDN.

5. The application according to claim 3, wherein The mass content of the antioxidant in the foamed polypropylene base material is 0 - 2000 ppm; The mass content of the plasticizer in the foamed polypropylene base material is 0 - 1000 ppm; The mass content of the filler in the foamed polypropylene base material is 0 - 2000 ppm; The mass content of the nucleating agent in the foamed polypropylene base material is 0 - 3000 ppm; The mass content of the antistatic agent in the foamed polypropylene base material is 0 - 1000 ppm.

6. The application according to claim 1, characterized in that, The fields with lightweight requirements include the packaging field.

7. A method for preparing a foamed polypropylene base material in the application according to any one of claims 1 to 6, characterized in that, Including the following steps: 1) After carrying out a polymerization reaction on a monomer, a Ziegler-Natta catalyst, an alkylaluminum cocatalyst, an external electron donor, and hydrogen, foamed polypropylene powder is obtained; 2) After granulating the foamed polypropylene powder and additives obtained in the above step, a foamed polypropylene base material is obtained.

8. The preparation method according to claim 7, wherein The polymerization includes bulk polymerization; The monomer includes propylene; The Ziegler-Natta catalyst includes a porous particulate or spherical catalyst containing a titanium compound with a magnesium halide as the carrier; The alkylaluminum cocatalyst includes one or more of triisobutylaluminum, triethylaluminum, dimethylaluminum chloride, diethylaluminum chloride, and isobutyldichloroaluminum; The external electron donor includes a silicon compound; The temperature of the polymerization reaction is 0 to 150 °C.

9. The preparation method according to claim 7, wherein The monomer includes propylene, and one or more of ethylene and / or α-olefins having 4 to 10 carbon atoms; The external electron donor includes one or more of cyclohexylmethyldimethoxysilane, cyclohexylmethyltrimethoxysilane, dicyclopentyldimethoxysilane, dicyclohexyldimethoxysilane, diisopropyldimethoxysilane, and phenyltrimethoxysilane; 10. The preparation method according to claim 7, characterized in that The polymerization method includes direct polymerization or a two-stage polymerization method; The temperature of the polymerization reaction is lower than the melting temperature of the copolymer.

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