Polypropylene composition, process for its preparation and use thereof

Abstract

The application discloses a polypropylene composition. The polypropylene composition comprises the following components in parts by weight: 29-51 parts of polypropylene melt-blown material, 20-30 parts of polypropylene resin, 5-15 parts of toughening agent, 2-20 parts of filler, 2-5 parts of compatilizer and 0-2 parts of auxiliary agent. The polypropylene resin is a copolymerized polypropylene resin, the content of EPR rubber phase in the polypropylene resin is 18-28%, the melt flow rate of the polypropylene resin under the condition of 230 DEG C and 2.16 kg is 10-58 g / 10 min, the melt flow rate of the polypropylene melt-blown material under the condition of 230 DEG C and 2.16 kg is 62-140 g / 10 min, and the toughening agent is a terpolymer of ethylene-propylene rubber, the Mooney viscosity of which under the condition of 125 DEG C is 20-40 MU. The polypropylene composition has smaller cell size, no bubble and hole is generated, and has good appearance and foaming effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and more particularly relates to a polypropylene composition, a preparation method and application thereof. BACKGROUND

[0002] Polypropylene is widely used in automobiles due to its small density, high cost performance, excellent heat resistance, rigidity, chemical corrosion resistance, easy processing and molding, and recycling, etc., and has become the largest and fastest-growing variety in plastics. In recent years, a large number of disposable epidemic prevention masks with melt-blown cloth as the material have been produced globally, and a large amount of melt-blown material and melt-blown cloth have been used as intermediate raw materials. With the end of the epidemic, a large amount of melt-blown material, melt-blown cloth and masks have been accumulated in stock in related factories; in addition, a large amount of polypropylene melt-blown material has been recycled from disposable masks, and how to better utilize these recycled materials is an important issue.

[0003] In recent years, with the development of household appliances or daily use industries, higher and higher requirements have been put forward for polypropylene materials for household appliances or daily use (such as door panels, hat racks, glove boxes and rear luggage compartment panels, etc.). In addition to basic performance and appearance requirements, lightweight requirements have also been put forward. In order to meet the lightweight requirements of parts, many non-safety parts consider using foaming process. The existing conventional foaming process usually foams polypropylene material into a foamed part with a wall thickness of 2.0 mm. However, with the increasing demand for lightweight, some manufacturers gradually develop foamed parts with a wall thickness of 1.5 mm or a thin wall of 1.2 mm. However, the foamed parts made from the existing polypropylene material after foaming often have problems such as air mark whitening, flow stress mark, large foaming cell size, and cell coalescence, which greatly affect the appearance of the foamed parts. Therefore, how to provide a polypropylene composition with small cell size and excellent appearance after foaming has become a technical problem to be solved. SUMMARY

[0004] In view of the above existing technical problems, the primary purpose of the present application is to provide a polypropylene composition having a small cell size, no cell coalescence, and good appearance and foaming effect.

[0005] The second purpose of the present application is to provide a preparation method of the polypropylene composition.

[0006] The third purpose of the present application is to provide an application of the polypropylene composition in the field of household appliances or daily use.

[0007] The fourth purpose of the present application is to provide a foamed part.

[0008] In order to achieve the above purposes, the present application is implemented by the following technical solutions:

[0009] A polypropylene composition comprises the following components in parts by weight: polypropylene melt-blown material 29-51 parts, polypropylene resin 20-30 parts, toughening agent 5-15 parts, filler 2-20 parts, compatibilizer 2-5 parts, and auxiliary 0-2 parts; the polypropylene resin is a copolymer polypropylene resin, the content of EPR rubber phase in the polypropylene resin is 18-28%, the melt flow rate of the polypropylene resin under the condition of 230 DEG C and 2.16 kg is 10-58 g / 10 min, the melt flow rate of the polypropylene melt-blown material under the condition of 230 DEG C and 2.16 kg is 62-140 g / 10 min, and the toughening agent is a terpolymer ethylene-propylene rubber, the Mooney viscosity of the toughening agent under the condition of 125 DEG C is 20-40 MU.

[0010] In the present application, the EPR rubber phase in the copolymer polypropylene and the ethylene-propylene rubber in the toughening agent terpolymer ethylene-propylene rubber are compatible, and can form a certain crosslinked network structure, which provides a suitable viscosity and network structure for micro-foaming, so that the cell size of the polypropylene composition is stable, and the problems such as coexistence of cells, stress whitening, and pits are reduced or eliminated. Further, the inventors find that when the content of the EPR rubber phase in the polypropylene resin is kept within a certain range, the polypropylene composition has good appearance. When the content of the EPR rubber phase in the copolymer polypropylene is low or high, the cell size of the polypropylene composition increases, and problems such as pits, stress whitening, and the like occur.

[0011] Further, the inventors find that the melt flow rate of the polypropylene resin and the melt flow rate of the polypropylene melt-blown material also have a significant influence on the appearance and cell formation of the polypropylene composition system. When the melt flow rate of the polypropylene resin or the polypropylene melt-blown material is low or high, the cell size of the polypropylene composition increases significantly, and problems such as pits, stress whitening, and the like occur, and the flowability of the molten material is not enough when foaming, so that the foamed plate cannot be filled.

[0012] The inventors find that the Mooney viscosity of the terpolymer ethylene-propylene rubber also greatly affects the appearance and foaming of the polypropylene composition. When the Mooney viscosity is low, the polypropylene composition is prone to coexistence of cells; and when the Mooney viscosity is high, the polypropylene composition is not easy to foam.

[0013] The present application uses a terpolymer ethylene-propylene rubber with a specific Mooney viscosity, a polypropylene resin with a specific content of EPR rubber phase, a polypropylene resin and a polypropylene melt-blown material with a specific melt flow rate, and other components in the composition, which effectively reduces the cell size of the polypropylene composition, and improves the problems such as coexistence of cells, stress whitening, pits, and the like. The polypropylene composition prepared by the present application has good appearance and foaming effect.

[0014] Specifically, the melt flow rate of the polypropylene melt-blown material in the present application can be 62 g / 10 min, 80 g / 10 min, 100 g / 10 min, 120 g / 10 min, 140 g / 10 min, etc., or an interval range formed by any of the above values, such as 62-100 g / 10 min, 80-120 g / 10 min, etc., and the present application is not limited thereto. The detection method of the melt flow rate of the polypropylene melt-blown material is ISO 1133-2011. Specifically, in some embodiments, recycled polypropylene melt-blown material can be used, which is conducive to the recycling of existing polypropylene melt-blown material, reduces production costs, and can realize industrial large-scale production.

[0015] Specifically, the melt flow rate of the polypropylene resin in the present application can be 10 g / 10 min, 20 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min, 58 g / 10 min, etc., or an interval range formed by any of the above values, such as 10-30 g / 10 min, 20-58 g / 10 min, etc., and the present application is not limited thereto. The detection method of the melt flow rate of the polypropylene resin is ISO 1133-2011.

[0016] Specifically, in the present application, the test method of the EPR rubber phase in the polypropylene resin is GPC test.

[0017] Specifically, in the present application, the mass percentage of the polypropylene resin in the polypropylene composition is not less than 22%. More specifically, in the present application, the mass percentage of the polypropylene melt-blown material in the polypropylene composition is not less than 34%.

[0018] Preferably, the filler is selected from one or more of talc, calcium carbonate, barium sulfate, wollastonite, glass microbeads, or magnesium silicate.

[0019] Preferably, the filler is talc, and the mesh number of the filler is 1250-5000. Preferably, the mesh number of the filler is 2500-3500. Within this preferred range, the polypropylene composition has a smaller cell size. The particle size range of the filler in the present application can be 1250 mesh, 1500 mesh, 2000 mesh, 2500 mesh, 3000 mesh, 3500 mesh, 4000 mesh, 4500 mesh, 5000 mesh, etc., or an interval range formed by any of the above values, such as 2500-3500 mesh, 3500-5000 mesh, etc., and the present application is not limited thereto.

[0020] Preferably, the compatibilizer is selected from one or more of polymeric polyol (POP), polyolefin copolymer (PO), very low density polyethylene (VLDPE). Further preferably, the compatibilizer is a polyolefin copolymer.

[0021] Preferably, the auxiliary agent is selected from one or more of an antioxidant, a light stabilizer, a lubricant, a toner.

[0022] Specifically, the antioxidant is selected from one or both of a hindered phenol antioxidant and a phosphite antioxidant, the hindered phenol antioxidant is selected from one or more of tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]pentaerythritol ester, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxyphenylmethyl)-2,4,6-trimethylbenzene, 6-tert-butyl-2,4-dimethylphenol, 2-tert-butyl-4,6-dimethylphenol, or 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, and the phosphite antioxidant is selected from one or more of tris[2,4-di-tert-butylphenyl] phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, or bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite. Specifically, the light stabilizer is a hindered amine light stabilizer, including but not limited to 2,2,6,6-tetramethyl-4-piperidinostearate. Specifically, the lubricant is a stearate lubricant, including but not limited to magnesium stearate, etc. Specifically, the toner can be selected from pigments commonly used in the art, such as carbon black, titanium dioxide, etc.

[0023] Specifically, the testing method of the Mooney viscosity of the toughening agent is ASTM D1646-2007.

[0024] Further, the present application also claims a method for preparing the polypropylene composition, wherein the polypropylene melt-blended material, the polypropylene resin, the toughening agent, the filler, the compatibilizer, and the optional auxiliary agent are mixed, melt-extruded, and granulated to obtain the polypropylene composition.

[0025] Preferably, the temperature during the melt-extrusion is 170-220°C.

[0026] Preferably, the screw rotation speed during the melt-extrusion is 350-450 rpm.

[0027] Further, the present application also claims the use of the above-mentioned polypropylene composition in the field of household appliances or daily use. Specifically, the polypropylene composition can be used to prepare products such as the outer shell of a thermally insulated box, the outer shell of an electrical appliance, a foamed decorative plate, a door panel, a coat rack, a glove box, and a rear luggage compartment panel, etc., especially in occasions with high requirements for the appearance and foaming of the polypropylene composition.

[0028] Further, the present application claims a foamed product prepared by injection molding the above-mentioned polypropylene composition.

[0029] Preferably, the injection foaming can be chemical foaming. More specifically, the foaming agent used in the chemical foaming process can be sodium bicarbonate or the like. More specifically, the mass ratio of the polypropylene composition and the foaming agent is 100:2-3.5.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] The present application uses EPDM rubber with a specific Mooney viscosity, polypropylene resin with a specific EPR rubber phase content, polypropylene resin with a specific melt flow rate, and polypropylene melt-blown material in combination with other components in the composition, effectively reducing the cell size of the polypropylene composition, improving the cell structure and appearance problems such as stress whitening, dimples, etc. The polypropylene composition prepared by the present application has good appearance and foaming effect. DETAILED DESCRIPTION

[0032] The present application is further illustrated below in conjunction with the specification and specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0033] Raw material description of examples and comparative examples:

[0034] Polypropylene resin:

[0035] PP1: Copolymerized polypropylene resin, melt flow rate under the condition of 230℃, 2.16kg is 9g / 10min, the content of EPR rubber phase is 21%, brand K8009, purchased from Sinopec.

[0036] PP2: Copolymerized polypropylene resin, melt flow rate under the condition of 230℃, 2.16kg is 58g / 10min, the content of EPR rubber phase is 27%, brand K9960, purchased from Sinopec.

[0037] PP3: Copolymerized polypropylene resin, melt flow rate under the condition of 230℃, 2.16kg is 110g / 10min, the content of EPR rubber phase is 18%, brand BI997, purchased from Hanwha Total.

[0038] PP4: Copolymerized polypropylene resin, melt flow rate under the condition of 230℃, 2.16kg is 10g / 10min, the content of EPR rubber phase is 16.3%, brand EP300M, purchased from China Shell.

[0039] PP5: Copolymerized polypropylene resin, melt flow rate under the condition of 230℃, 2.16kg is 30g / 10min, the content of EPR rubber phase is 31%, brand K9829H, purchased from Sinopec.

[0040] PP6: Copolymer polypropylene resin, melt flow rate of 10 g / 10 min at 230 °C, 2.16 kg, EPR rubber phase content of 18%, grade HHP-8, purchased from Sinopec.

[0041] PP7: Copolymer polypropylene resin, melt flow rate of 30 g / 10 min at 230 °C, 2.16 kg, EPR rubber phase content of 28%, grade K9930H, purchased from Sinopec.

[0042] PP8: Homopolymer polypropylene resin, melt flow rate of 53 g / 10 min at 230 °C, 2.16 kg, grade S980, purchased from Sinopec.

[0043] Polypropylene melt blown 1: Melt flow rate of 45 g / 10 min at 230 °C, 2.16 kg, grade MM45-S, purchased from Sinopec.

[0044] Polypropylene melt blown 2: Melt flow rate of 62 g / 10 min at 230 °C, 2.16 kg, grade MR60MC2, purchased from Hanwha-Dow.

[0045] Polypropylene melt blown 3: Melt flow rate of 140 g / 10 min at 230 °C, 2.16 kg, grade MH140CN0, purchased from Hanwha-Dow.

[0046] Polypropylene melt blown 4: Melt flow rate of 150 g / 10 min at 230 °C, 2.16 kg, grade MH7900, purchased from LG, Korea.

[0047] Toughener 1: Terpolymer ethylene-propylene rubber, Mooney viscosity of 20 MU at 125 °C, grade 3722P, purchased from Dow, USA.

[0048] Toughener 2: Terpolymer ethylene-propylene rubber, Mooney viscosity of 40 MU at 125 °C, grade 4640, purchased from Dow, USA.

[0049] Toughener 3: Ethylene-butene copolymer, Mooney viscosity of 24 MU at 125 °C, grade POE ENGAGE 7367, purchased from Dow Chemical.

[0050] Toughener 4: Terpolymer ethylene-propylene rubber, Mooney viscosity of 19 MU at 125 °C, grade 3722P, purchased from Dow Chemical.

[0051] Toughener 5: Terpolymer ethylene-propylene rubber, Mooney viscosity of 70 MU at 125 °C, grade 4770R, purchased from Dow Chemical.

[0052] Filler 1: talcum powder, mesh number 1250, grade TYT-8875B, purchased from Liaoning Tianyuan.

[0053] Filler 2: talcum powder, mesh number 5000, grade TYT-3000A, purchased from Liaoning Tianyuan.

[0054] Filler 3: talcum powder, mesh number 3000, grade TYT-777A, purchased from Liaoning Tianyuan Company.

[0055] Compatibilizer 1: polyolefin copolymer, grade ENGAGE 11527, purchased from the United States Dow.

[0056] Color powder: carbon black BP717, commercially available.

[0057] Antioxidant: tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, commercially available.

[0058] Light stabilizer: 2,2,6,6-tetramethyl-4-piperidine stearate, commercially available.

[0059] Lubricant: magnesium stearate, commercially available.

[0060] Unless otherwise specified, each component (such as color powder, antioxidant, etc.) used in each parallel example and comparative example is the same commercially available product.

[0061] Example 1

[0062] The weight parts of the raw materials used in Example 1 are shown in Table 1.

[0063] A method for preparing a polypropylene composition, the specific steps include:

[0064] The polypropylene melt-blown material, polypropylene resin, toughening agent, filler, compatibilizer and additive were weighed according to the weight parts in Table 1, mixed in a high-speed mixer for 30 s, then transferred to a twin-screw extruder for melt mixing, the temperature of melt mixing was 200°C, the screw rotation speed was 400 r / min, and then extruded and granulated to obtain a polypropylene composition.

[0065] Examples 2-9

[0066] The weight parts of the raw materials used in each of the following examples are shown in Table 1.

[0067] The specific preparation steps of each of the following examples are the same as those of Example 1.

[0068] Comparative Examples 1-10

[0069] The weight parts of the raw materials used in each of the following comparative examples are shown in Table 2.

[0070] The specific preparation steps of each of the comparative examples are the same as those of Example 1.

[0071] Table 1 is the formulation components of each example:

[0072] Table 1

[0073]

[0074] Table 2 is the formulation components of each comparative example:

[0075] Table 2

[0076]

[0077]

[0078] The polypropylene compositions prepared in the above examples and comparative examples were injection foamed, using an injection molding machine, an injection speed of 100 mm / s, a foaming agent of EE25C from Taiwan Yonghe, a mass ratio of polypropylene composition to foaming agent of 100:3, an injection molding temperature of 200°C, and a foaming mold size of 110*326*1.2 mm, to obtain foamed plates. The foamed plates prepared in the above examples and comparative examples were tested according to the following test methods:

[0079] (1) Flow length: the flow length was tested using a spiral mold of Jinfa; the longer the flow, the better it is suitable for injection foaming of thin plate parts, and the thinner the wall thickness.

[0080] (2) Cell uniformity: the foamed plate was cut open with a slicing machine and observed with the naked eye (or a microscope).

[0081] (3) Cell size: the foamed plate was cut open with a slicing machine, and the cell size was observed and measured using a microscope, and the average cell size was counted.

[0082] (4) Appearance: the foamed plate was placed horizontally on the desktop, and the appearance of the foamed plate was checked for fullness (i.e. not reaching the end of the plate), air marks, stress whitening, impact marks, dimples, air cyclones, and other appearance defects.

[0083] Table 3 and Table 4 are the performance test results of each example and comparative example, respectively.

[0084] Table 3

[0085]

[0086]

[0087] Table 4

[0088]

[0089]

[0090] As can be seen from the data of the examples, the present application effectively reduces the cell size of the polypropylene composition, improves the cell and hole and appearance problems such as stress whitening, dimples and the like by using the toughening agent with specific Mooney viscosity, the polypropylene resin with specific EPR rubber phase content, the polypropylene resin with specific melt flow rate and the polypropylene melt blown material and matching other components in the composition. The prepared polypropylene composition does not have cell and hole and has smaller cell size, the cell size is ≤175 μm, and has good appearance.

[0091] As can be seen from Example 1, Comparative Examples 1-4 and Comparative Example 10, when using the copolymerized polypropylene, or the content of the EPR rubber phase in the polypropylene resin is in the range of 18-28%, or the melt flow rate is in the range of 10-58 g / 10 min, the prepared polypropylene composition has smaller cell size, no cell and hole, and no appearance problems such as stress whitening, dimples and the like.

[0092] As can be seen from Example 1 and Comparative Examples 5-6, when the melt flow rate of the polypropylene melt blown material is in a specific range, the prepared polypropylene composition has smaller cell size, no cell and hole, and no appearance problems such as stress whitening and the like.

[0093] As can be seen from Example 1 and Comparative Examples 7-9, when the toughening agent is the EPDM rubber with specific Mooney viscosity, the prepared polypropylene composition has smaller cell size, no cell and hole, and no appearance problems such as stress whitening and the like.

[0094] The foregoing examples are illustrative only and are not meant to limit the scope of the application as described in the claims. The examples presented herein are intended to demonstrate the actual results obtained by the inventors. Accordingly, the inventors intend that the appended claims be construed as broadly as possible to encompass the features of the methods described herein. Some numerical ranges are included in the claims. Such ranges are intended to cover every possible subrange found within the broader range. Variations to the disclosed embodiments can become apparent to those of ordinary skill in the art upon reading this disclosure. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the claimed subject matter to include all such variations.

Claims

1. A polypropylene composition for foamed articles, characterized in that, The polypropylene melt-blown material, the polypropylene resin, the toughening agent, the filler, the compatibilizer and the optional auxiliary are mixed, melt-extruded, and granulated to obtain the polypropylene composition for the foamed product. The polypropylene resin is a copolymerized polypropylene resin, and the content of EPR rubber phase in the polypropylene resin is 18-28%; the melt flow rate of the polypropylene resin at 230℃ and under a load of 2.16 kg is 10-58 g / 10 min. The melt flow rate of the polypropylene melt-blown material at 230℃ and under a load of 2.16 kg is 62-140 g / 10 min. The toughening agent is a terpolymerized ethylene-propylene rubber, and the Mooney viscosity of the toughening agent at 125℃ is 20-40 MU.

2. The polypropylene composition for a foamed article according to claim 1, characterized in that, The filler is selected from one or more of talc, calcium carbonate, barium sulfate, wollastonite, glass microbeads or magnesium silicate.

3. The polypropylene composition for a foamed article according to claim 2, characterized in that, The filler is talc, and the mesh number of the filler is 1250-5000.

4. The polypropylene composition for a foamed article according to claim 1, characterized in that, The compatibilizer is selected from one or more of polymeric polyol, polyolefin copolymer and very low density polyethylene.

5. The polypropylene composition for a foamed article according to claim 4, characterized in that, The compatibilizer is a polyolefin copolymer.

6. The polypropylene composition for a foamed article according to claim 1, characterized in that, The auxiliary is selected from one or more of antioxidant, light stabilizer, lubricant and colorant.

7. The polypropylene composition for a foamed article according to claim 6, characterized in that, The antioxidant is selected from one or both of phenolic antioxidant and phosphite antioxidant; the light stabilizer is a hindered amine light stabilizer; and the lubricant is a stearic acid lubricant.

8. Process for the production of a polypropylene composition for foamed articles according to any one of claims 1 to 7, characterized in that, The polypropylene melt-blown material, the polypropylene resin, the toughening agent, the filler, the compatibilizer and the optional auxiliary are mixed, melt-extruded, and granulated to obtain the polypropylene composition for the foamed product.

9. Use of the polypropylene composition for the foamed product according to any one of claims 1-7 in the field of household appliances or daily use.

10. A foamed article characterized by, The polypropylene composition for the foamed product according to any one of claims 1-7 is foamed by injection molding.

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