Melt reinforced polypropylene composition and preparation method thereof

Abstract

The invention belongs to the technical field of polypropylene modification, and particularly relates to a melt reinforced polypropylene composition and a preparation method thereof. The polypropylene composition comprises (A) polypropylene matrix resin, (B) a polyolefin elastomer graft, and (C) polyethylene glycol and / or polyoxyethylene, the total weight of the polypropylene composition is 100 parts by weight, and the polypropylene composition comprises the following components in parts by weight: 0.1-10 parts of polyolefin elastomer graft, 0.1-8 parts of polyethylene glycol and / or polyoxyethylene, and the balance of polypropylene matrix resin, the molecular weight of the polyethylene glycol and / or polyoxyethylene is 2000-200000. According to the invention, the melt strength and processability of the obtained polypropylene composition can be improved, and the processing energy consumption (torque reduction) can be reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene modification, and in particular relates to a melt-enhanced polypropylene composition and a preparation method thereof. Background Art

[0002] Polypropylene (PP) has the advantages of low density, low cost, excellent processing performance and physical properties, and is widely used in many fields. During use, many parts require the material to have high melt strength during processing, and the softening point of polypropylene is close to the melting point. When the temperature is higher than the melting point, its melt strength and melt viscosity drop sharply, resulting in melt processing defects such as cell collapse during extrusion foaming, edge curling and shrinkage during high-speed extrusion coating, and uneven product wall thickness during thermoforming. Therefore, the melt strength characteristics of polypropylene are modified by various means in this field, aiming to prepare modified polypropylene materials with high melt strength.

[0003] Chinese patent document CN101423615A discloses a method for improving the melt strength of thermoplastic polymers, wherein a polytetrafluoroethylene (PTFE) with fibrillation characteristics is directly added to the melt of thermoplastic polymers by an online drying method, with the purpose of improving the stability of processing processes such as extrusion, blow molding, and foaming and the anti-dripping property of flame retardant materials. The method directly uses high molecular weight polytetrafluoroethylene (PTFE) dispersed in an emulsion as a melt enhancer, mixes it with a thermoplastic resin, and then dries it online with hot air through a vertical drying system, PTFE does not produce fibrillation, and the fallen resin particles directly enter the mixing system for mixing and extrusion, solving the problem of feeding PTFE with fibrillation characteristics. This method is a universal and simple method, suitable for all thermoplastic polymers, characterized by not affecting the molecular weight and physical and mechanical properties of the polymer, low cost, significant effect, and easy to achieve large-scale production; however, the melt enhancer added is a high molecular weight polytetrafluoroethylene with fibrillation characteristics, with a high molecular weight, high processing temperature and energy consumption, and complex processing technology.

[0004] Chinese patent document CN108530746A discloses a method for preparing a foamed polypropylene sheet based on elongational rheology technology, including: ① premixing: adding homopolymerized polypropylene, copolymerized polypropylene, melt-enhanced masterbatch, foaming nucleating agent, chemical foaming agent, lubricant, etc. to a high mixer for premixing; ② foaming molding: adding the premixed materials to the elongational rheology plasticizing extrusion equipment to plasticize them, and allowing the gas after the decomposition of the foaming agent to be evenly dispersed in the polypropylene melt, and then extruding through the foaming sheet die and rolling by three rollers to obtain the foamed polypropylene sheet. The foamed polypropylene sheet prepared by the inventive method has uniform and fine pores, high foaming ratio and low open porosity compared to the foamed material extruded by the traditional screw equipment. At the same time, the product has excellent mechanical properties, simple production process, low cost, and is suitable for large-scale industrial production. Among them, the melt-enhanced masterbatch as a melt enhancer is a composite of ethylene-octene copolymer and polyethylene, which is prepared by elongational rheology plasticizing extrusion equipment, and has high molecular weight, processing temperature and energy consumption.

[0005] Chinese patent document CN112063048A discloses a low-dielectric and high-melt-strength flame-retardant polypropylene material and a preparation method thereof. The raw materials used include polypropylene, polyethylene, a toughening agent, a flame retardant, an organically modified POSS, a coupling agent, an initiator, an anti-dripping agent and other additives. The invention utilizes the synergistic flame retardant effect of the organically modified POSS and the flame retardant system to reduce the amount of the flame retardant by 20% and still achieve a flame retardant grade of V0. The organically modified POSS and the toughening agent have a synergistic melt-enhancing effect, and the melt strength of the composite material can be increased by 20-100 Pa·s to 70-150 Pa·s, thereby ensuring the melt integrity of the material under vacuum forming / foaming / extrusion conditions. At the same time, due to the hollow structure of the POSS itself, the dielectric constant of the composite material can be reduced, thereby expanding the application field. In this invention, a synergistic melt strengthening effect is exerted by polyhedral oligomeric silsesquioxane (POSS) (organically modified POSS) and a toughening agent (at least one of ethylene propylene diene monomer rubber EPDM, styrene-ethylene-butylene-styrene copolymer SEBS, and ethylene-octene copolymer POE). However, there are many components in the formula, the processing temperature and energy consumption are high, and the processing technology is complicated.

[0006] Chinese patent document CN115403863A discloses a polypropylene composition and its preparation method and application, wherein the polypropylene composition comprises the following components in parts by weight: 40-75 parts of polypropylene, 5-10 parts of toughening agent, 7-15 parts of melt enhancer, 0.5-5 parts of molecular chain repair agent, 20-50 parts of filler, and 0.5-2 parts of auxiliary agent; the molecular chain repair agent is vinyl trimethoxysilane and diisopropylbenzene peroxide. The polypropylene composition obtained by the invention has high melt strength and mechanical properties, and can be applied to multi-layer extrusion and complex internal hollow structures. At the same time, the polypropylene composition has good extrusion stability, can be repeatedly broken and reused, and is conducive to recycling; wherein the melt enhancer used is polypropylene with a melt flow rate of <5g / 10min and a weight average molecular weight of >1 million; the processing temperature and energy consumption are high, and the processing technology is complex.

[0007] In summary, it can be seen that the existing technology mainly uses high molecular weight polytetrafluoroethylene particles, high molecular weight polypropylene, organic modified POSS, etc. as melt enhancers for melt enhancement modification, which leads to high processing temperature and energy consumption and complex processing technology. In view of this, it is worthwhile to continue to explore modification methods that can improve the melt strength and processability of materials while reducing processing energy consumption. Summary of the invention

[0008] In view of the problems of high processing energy consumption and complex process in the prior art for modifying the melt strength of polypropylene, the object of the present invention is to provide a melt-enhanced polypropylene composition and a preparation method thereof, which can improve the melt strength and processability of the obtained polypropylene composition while reducing processing energy consumption (torque reduction).

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] In a first aspect, a melt-enhanced polypropylene composition is provided, the polypropylene composition comprising: (A) a polypropylene matrix resin, (B) a polyolefin elastomer graft, (C) polyethylene glycol and / or polyethylene oxide;

[0011] Taking the total weight of the polypropylene composition as 100 parts by weight, the contents of the components in the polypropylene composition are as follows:

[0012] The amount of the polyolefin elastomer graft is 0.1-10 parts by weight (e.g., 0.2 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.8 parts by weight, 1.5 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 8 parts by weight), preferably 1-6 parts by weight;

[0013] The amount of polyethylene glycol and / or polyethylene oxide is 0.1-8 parts by weight (e.g., 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, 0.8 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 7 parts by weight), preferably 0.5-6 parts by weight;

[0014] The balance is polypropylene matrix resin.

[0015] According to the polypropylene composition provided by the present invention, in some embodiments, the molecular weight of component (C) is 2000-200000 (for example, 2500, 4000, 5000, 8000, 10000, 20000, 40000, 50000, 60000, 80000, 90000, 120000, 150000, 180000), preferably 3000-100000, and more preferably 3000-30000.

[0016] For example, the molecular weight of the polyethylene glycol may be 2000-200000; the molecular weight of the polyethylene oxide may be 2000-200000.

[0017] In some embodiments, the polyolefin elastomer graft is selected from at least one of polyolefin elastomer grafted maleic anhydride (POE-g-MAH), polyolefin elastomer grafted glycidyl methacrylate (POE-g-GMA) and derivatives thereof.

[0018] In some embodiments, the polyolefin elastomer graft is polyolefin elastomer grafted with maleic anhydride (POE-g-MAH).

[0019] In some embodiments, the polyolefin elastomer graft is at least one selected from the group consisting of a graft of ethylene and 1-butene copolymer, a graft of ethylene and 1-hexene copolymer, and a graft of ethylene and 1-octene copolymer.

[0020] In some embodiments, the polyolefin elastomer graft is a graft of ethylene and 1-octene copolymer.

[0021] In some embodiments, the polyolefin elastomer graft has a melt index of 0.5-15 g / 10 min (e.g., 0.6 g / 10 min, 1.0 g / 10 min, 2 g / 10 min, 5 g / 10 min, 8 g / 10 min, 12 g / 10 min, 14 g / 10 min) at 190°C and a load of 2.16 kg, preferably 0.5-10 g / 10 min.

[0022] In some embodiments, the density of the polyolefin elastomer graft is 0.86-0.89 g / cm 3(For example, 0.865 g / cm 3 , 0.87g / cm 3 , 0.872g / cm 3 , 0.875g / cm 3 , 0.88g / cm 3 , 0.882g / cm 3 , 0.885g / cm 3 ).

[0023] In some embodiments, the grafting rate of the polyolefin elastomer graft is greater than or equal to 0.2% (e.g., 0.25%, 0.4%, 0.5%, 0.6%, 0.8%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%), preferably 0.3%-2.0%.

[0024] In some embodiments, the weight ratio of the polyolefin elastomer graft to the polyethylene glycol and / or polyethylene oxide is (0.1-10):1 (e.g., 0.2:1, 0.4:1, 0.6:1, 1:1, 2:1, 4:1, 5:1, 6:1, 9:1), preferably (0.5-8):1, and more preferably (0.8-5):1.

[0025] In some embodiments, the polypropylene matrix resin is selected from polypropylene homopolymers and / or polypropylene random copolymers.

[0026] In some embodiments, the polypropylene base resin is a polypropylene homopolymer having a melt index of 1-100 g / 10 min (e.g., 2 g / 10 min, 4 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min, 60 g / 10 min, 70 g / 10 min, 90 g / 10 min) at 230 ° C and a load of 2.16 kg, preferably 1-80 g / 10 min.

[0027] In some embodiments, the polypropylene matrix resin is a polypropylene random copolymer, which has a melt index of 1-60 g / 10 min (for example, 2 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, 40 g / 10 min, 50 g / 10 min) at 230°C and a load of 2.16 kg, wherein the comonomer is ethylene and the comonomer content is 0-5% (for example, 0.1%, 0.2%, 0.5%, 1.0%, 2.0%, 4.0%, 4.5%).

[0028] In some embodiments, the polypropylene matrix resin is a polypropylene random copolymer having a melt index of 1-55 g / 10 min at 230° C. and a load of 2.16 kg, wherein the comonomer is ethylene and the comonomer content is 0-4%.

[0029] In a second aspect, a method for preparing the polypropylene composition as described above is provided, wherein the preparation method comprises the following steps:

[0030] The polypropylene matrix resin, the polyolefin elastomer graft, polyethylene glycol and / or polyethylene oxide are mixed, and then the obtained mixture is melt-extruded and granulated to obtain the melt-enhanced polypropylene composition.

[0031] According to the preparation method provided by the present invention, in some embodiments, the melt extrusion is carried out in a twin-screw extruder;

[0032] In some embodiments, the twin-screw extruder has a screw aspect ratio of 10-100 (e.g., 15, 20, 25, 30, 50, 80), and an extrusion temperature of 110-220°C (e.g., 115°C, 120°C, 130°C, 140°C, 150°C, 160°C, 180°C, 200°C).

[0033] In the preparation method of the present invention, melt extrusion and granulation can be achieved by conventional operations in the art; the equipment and process conditions involved in the melt extrusion and granulation process can also be conventionally selected in the art, which will not be described in detail here.

[0034] In the polypropylene composition of the present invention, the melt enhancer selected is polyolefin elastomer graft + polyethylene glycol and / or polyethylene oxide; by synergistically adding polyolefin elastomer graft and polyethylene glycol and / or polyethylene oxide, the melt strength and processability of the polypropylene composition material can be improved, and the processing energy consumption (torque reduction) can also be reduced. DETAILED DESCRIPTION

[0035] In order to understand the technical features and content of the present invention in detail, the preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described in the embodiments, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. For those who do not specify specific conditions in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer.

[0036] <Source of raw materials>

[0037] In the following examples and comparative examples, the sources of some reagents or raw materials used, without specifying the manufacturer, are all conventional products that can be purchased commercially.

[0038] Polypropylene matrix resin: homopolymer polypropylene H 1500 (Korea Lotte PPH), homopolymer polypropylene K1870, copolymer polypropylene EP300K;

[0039] Polyolefin elastomer graft (POE-MAH): GR216, melt index at 190°C and load of 2.16 kg is 1.25 g / 10 min, density is 0.875 g / cm 3 , the grafting rate is 0.5%-1%;

[0040] Polyethylene glycol: PEG-4000, PEG-8000, PEG-20000;

[0041] Polyethylene oxide: PEO-50000, PEO-100000, PEO-300000.

[0042] <Test Method>

[0043] 1. Melt index: The melt index of the obtained polypropylene composition sample was tested using a CEΛST 7026 melt index meter produced in Italy in accordance with ASTM D-1238. The test temperature was 230° C. and the load was 2.16 kg.

[0044] 2. Zero shear viscosity (210°C): The frequency scanning was performed using a DHR-2 rotational rheometer from TA Company of the United States. The frequency scanning program was set as follows: angular frequency scanning range 100 rad / s-0.05 rad / s, strain 1.25%, and scanning temperature 210°C.

[0045] After the test is completed, the frequency scan results are converted into flow curves through Cox-Merz transformation, and the zero shear viscosity data are obtained through Williamson model fitting.

[0046] 3. Torque: According to the formulations of the embodiments and comparative examples, polypropylene matrix resin, polyolefin elastomer graft, polyethylene glycol and / or polyethylene oxide were mixed, and the resulting mixture was melt-extruded and granulated; a German HAAKE parallel co-rotating twin-screw extruder HAAKE Rheomex PTW 16OS was used for melt blending and extrusion, and the real-time torque of the mixture was tested using PolyLab OS software.

[0047] In each embodiment and comparative example, the preparation method of the polypropylene composition comprises the following steps:

[0048] A polypropylene matrix resin, a polyolefin elastomer graft, polyethylene glycol and / or polyethylene oxide are mixed, and the obtained mixture is melt-extruded and granulated; a German HAAKE parallel co-rotating twin-screw extruder HAAKE RheomexPTW 16OS is used for melt-blending and extrusion, and the real-time torque of the mixed material is tested by PolyLab OS software; the 10-stage screw temperature of the twin-screw extruder is: 120°C-150°C-175°C-180°C-185°C-190°C-195°C-195°C-205°C-200°C, wherein the temperature of the first stage is 120°C, the temperature of the tenth stage is 200°C, and the rotation speed is 100r / min; and the aspect ratio of the screw is 40 / 1.

[0049] In each embodiment, the raw material components (polypropylene matrix resin, polyolefin elastomer graft, polyethylene glycol and / or polyethylene oxide) in the polypropylene composition and their contents, as well as the performance test results of the obtained products are shown in Table 1-2.

[0050] In each comparative example, the raw material components and their contents in the polypropylene composition, as well as the performance test results of the obtained products are shown in Tables 3-5.

[0051] Table 1 Composition formula and product performance test

[0052]

[0053] Table 2 Composition formula and product performance test

[0054]

[0055]

[0056] Table 3 Composition formula and product performance test

[0057]

[0058] Table 4 Composition formula and product performance test

[0059]

[0060] Table 5 Composition formula and product performance test

[0061]

[0062] It can be seen from the experimental results in Tables 1-2 that by adopting the technical scheme of the present invention, selecting polyolefin elastomer grafts and polyethylene glycol or polyethylene oxide and controlling the ratio of the two within an appropriate range, the melt strength and processability of the polypropylene composition obtained can be improved while reducing processing energy consumption.

[0063] For the polypropylene matrix H1500 system, it can be seen from Example 1 compared with the comparative examples shown in Table 3 that POE-MAH+PEG as a melt enhancer has a synergistic melt enhancement effect on the PP composition system, and also reduces the processing torque (reduces processing energy consumption); if the polyolefin elastomer graft and polyethylene glycol or polyethylene oxide are not added at the same time, or the ratio and amount of the two are not within the appropriate range, the synergistic effect cannot be exerted, and the melt strength of the polypropylene composition cannot be improved, the processing performance deteriorates, and the processing energy consumption is also high. In addition, it can be seen from the results of Comparative Example 6 that when synergistically acting with polyethylene glycol or polyethylene oxide, the improvement effect of using POE-MAH on the product is better than that of PP-MAH.

[0064] For the polypropylene matrix K1870 system, it can be seen from Examples 5-9 compared with the comparative examples shown in Table 4 that POE-MAH+PEG / PEO as a melt enhancer has a synergistic melt enhancing effect on the PP composition system; if the molecular weight of the selected polyethylene glycol or polyethylene oxide is inappropriate, the extrusion processing performance of the product will be very poor; or if the polyolefin elastomer graft and polyethylene glycol or polyethylene oxide are not added at the same time, a good synergistic effect cannot be exerted, and the melt strength of the polypropylene composition cannot be improved.

[0065] For the polypropylene matrix EP300K system, POE-MAH+PEG as a melt enhancer has a synergistic melt strengthening effect on the PP composition system, and also reduces the processing torque (reduces processing energy consumption); it can also be seen from Example 4 compared with the comparative examples shown in Table 5 that if the polyolefin elastomer graft and polyethylene glycol or polyethylene oxide are not added at the same time, the melt strength of the polypropylene composition cannot be improved, and the processing energy consumption is also high.

[0066] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the spirit of the present invention.

Claims

1. A melt-enhanced polypropylene composition, wherein: The polypropylene composition comprises: (A) a polypropylene base resin, (B) a polyolefin elastomer graft, and (C) polyethylene glycol and / or polyethylene oxide; Taking the total weight of the polypropylene composition as 100 parts by weight, the contents of the components in the polypropylene composition are as follows: The amount of the polyolefin elastomer graft is 0.1-10 parts by weight, preferably 1-6 parts by weight; The amount of polyethylene glycol and / or polyethylene oxide is 0.1-8 parts by weight, preferably 0.5-6 parts by weight; The balance is polypropylene matrix resin.

2. The polypropylene composition according to claim 1, wherein The molecular weight of component (C) is 2,000-200,000, preferably 3,000-100,000, more preferably 3,000-30,000.

3. The polypropylene composition according to claim 1, wherein The polyolefin elastomer grafted product is selected from at least one of polyolefin elastomer grafted maleic anhydride, polyolefin elastomer grafted glycidyl methacrylate and derivatives thereof; Preferably, the polyolefin elastomer grafted product is polyolefin elastomer grafted with maleic anhydride.

4. The polypropylene composition according to any one of claims 1 to 3, wherein The polyolefin elastomer graft is selected from at least one of a graft of ethylene and 1-butene copolymer, a graft of ethylene and 1-hexene copolymer, and a graft of ethylene and 1-octene copolymer; Preferably, the polyolefin elastomer graft is a graft of ethylene and 1-octene copolymer.

5. The polypropylene composition according to any one of claims 1 to 4, wherein The polyolefin elastomer graft has a melt index of 0.5-15 g / 10 min, preferably 0.5-10 g / 10 min, at 190° C. and a load of 2.16 kg; the density of the polyolefin elastomer graft is 0.86-0.89 g / cm 3 .

6. The polypropylene composition according to any one of claims 1 to 5, wherein The grafting rate of the polyolefin elastomer graft is greater than or equal to 0.2%, preferably 0.3%-2.0%.

7. The polypropylene composition according to any one of claims 1 to 6, wherein The weight ratio of the polyolefin elastomer graft to the polyethylene glycol and / or polyethylene oxide is (0.1-10):1, preferably (0.5-8):1, and more preferably (0.8-5):

1.

8. The polypropylene composition according to any one of claims 1 to 7, wherein The polypropylene matrix resin is selected from polypropylene homopolymer and / or polypropylene random copolymer; Preferably, the polypropylene matrix resin is a polypropylene homopolymer, and its melt index at 230° C. and a load of 2.16 kg is 1-100 g / 10 min, preferably 1-80 g / 10 min; Preferably, the polypropylene matrix resin is a polypropylene random copolymer, whose melt index at 230°C and a load of 2.16 kg is 1-60 g / 10 min, wherein the comonomer is ethylene and the comonomer content is 0-5%; more preferably, the polypropylene matrix resin is a polypropylene random copolymer, whose melt index at 230°C and a load of 2.16 kg is 1-55 g / 10 min, wherein the comonomer is ethylene and the comonomer content is 0-4%.

9. The method for preparing a polypropylene composition according to any one of claims 1 to 8, wherein: The preparation method comprises the following steps: The polypropylene matrix resin, the polyolefin elastomer graft, polyethylene glycol and / or polyethylene oxide are mixed, and then the obtained mixture is melt-extruded and granulated to obtain the melt-enhanced polypropylene composition.

10. The preparation method according to claim 9, wherein: The melt extrusion is carried out in a twin-screw extruder; Preferably, the screw aspect ratio of the twin-screw extruder is 10-100, and the extrusion temperature is 110-220°C.

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