A polypropylene composition and its preparation method and application

Abstract

The present invention discloses a polypropylene composition. The polypropylene composition comprises the following components by weight: 49-71 parts of polypropylene resin, 8-13 parts of toughening agent, 15-25 parts of filler, 1-5 parts of polyether polyol, and 0-0.8 parts of auxiliary agent. The present invention adds polyether polyol to the polypropylene composition. When the polypropylene composition is injection molded into a product, different streams of the polypropylene composition meet at the intersection of holes or the intersection of streams. The polyether polyol can promote the rapid formation of crosslinking points of different streams, so that the different streams after crosslinking tend to be flat more quickly, thereby reducing the height of the pressure line protrusion of the product and improving the appearance of the product.

Description

Technical Field

[0001] The invention belongs to the technical field of polypropylene plastics, and more specifically, relates to a polypropylene composition and a preparation method and application thereof. Background Art

[0002] Polypropylene has the advantages of high strength, low density, heat resistance, chemical resistance, and wide processing temperature range. As lightweight technology in the domestic and foreign automotive industries has become a research hotspot, polypropylene has also been rapidly applied and developed in automotive accessories and structural parts. Modified polypropylene has become the mainstream material for the production of automotive bumpers. Automotive bumper materials are required to have excellent impact resistance, fluidity, rigidity, thermal stability, and dimensional stability, and especially good sprayability and appearance.

[0003] At present, there are related patents that have been studied and improved on the appearance of polypropylene. For example, patent CN112266532A discloses a good-looking sprayable polypropylene reinforced composite material. The product has good mechanical properties and can meet the development trends of lightweight, olefinization, and high performance required by the current automotive industry. However, the appearance of the composite material still has floating fiber problems due to the addition of glass fiber, and there are problems such as appearance welding marks and flow marks. In addition, due to mold design reasons, when the automobile bumper is injected, a raised pressure line will be formed at the intersection of the holes of the mold or the intersection of the material flow due to the different pressures when the material flow contacts. The formation of this raised pressure line greatly affects the appearance of the product and affects the use of consumers. Therefore, how to reduce the pressure when the material flow intersects, and then reduce the raised height of the pressure line has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In view of the above existing technical problems, the primary purpose of the present invention is to provide a polypropylene composition which can significantly reduce the height of the protrusion of the pressure line when injection-molded into a product, thereby making the product have a good appearance.

[0005] The second object of the present invention is to provide a method for preparing the polypropylene composition.

[0006] The third object of the present invention is to provide a use of a polypropylene composition in preparing an injection molded product with a weakened pressure line.

[0007] A fourth object of the present invention is to provide an injection molded product with a weakened pressure line.

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

[0009] A polypropylene composition comprises the following components by weight: 49-71 parts of polypropylene resin, 8-13 parts of toughening agent, 15-25 parts of filler, 1-5 parts of polyether polyol and 0-0.8 parts of auxiliary agent.

[0010] The present invention adds polyether polyol to the polypropylene composition. When the polypropylene composition is injection molded into a product, different streams of the polypropylene composition meet at the intersection of holes or streams. The applicant speculates that the hydroxyl groups in the polyether polyol can "bridge" between parallel molecular chains of polypropylene, which can prompt different streams to quickly form crosslinking points for crosslinking, thereby reducing the pressure when the streams meet, so that the different streams after crosslinking tend to be flat more quickly, thereby reducing the height of the pressure line protrusion of the product and improving the appearance of the product. The toughening agent can improve the toughness of polypropylene and form a crosslinking network in the polypropylene matrix. When two streams converge, the pressure difference between the streams can be reduced, thereby reducing the formation of the pressure line.

[0011] Preferably, the polyether polyol is a polyether triol. More specifically, the polyether triol may be one or more of polyoxyethylene triol, polyoxypropylene triol, and polyoxyethylene-oxypropylene triol.

[0012] Preferably, the weight average molecular weight of the polyether polyol is 450 to 1350. Preferably, the weight average molecular weight of the polyether polyol is 650 to 1350. Further preferably, the weight average molecular weight of the polyether polyol is 1000 to 1350. At this preferred weight average molecular weight, the polypropylene composition is more likely to form crosslinking points, thereby reducing the height of the pressure line protrusion of the product. Specifically, the weight average molecular weight of the polyether polyol described in the present invention can be 450, 550, 650, 750, 850, 950, 1050, 1150, 1250, 1350, etc., or an interval range formed by any of the above values, such as 450 to 850, 1050 to 1250, etc., and the present invention is not limited thereto. Specifically, the test method for the weight average molecular weight of the polyether polyol is: high temperature GPC method.

[0013] Preferably, the melt flow rate of the polypropylene resin at 230°C and 2.16kg is 10 to 60g / 10min. Further preferably, the melt flow rate of the polypropylene resin at 230°C and 2.16kg is 30 to 60g / 10min. In this preferred range, the polypropylene composition is more likely to form crosslinking points, thereby reducing the height of the pressure line protrusion of the product. Specifically, the melt flow rate of the polypropylene resin in the present invention can be 10g / 10min, 20g / 10min, 30g / 10min, 40g / 10min, 50g / 10min, 60g / 10min, etc., or an interval range formed by any of the above values, such as 10 to 30g / 10min, 20 to 50g / 10min, etc., and the present invention is not limited thereto. Specifically, the test method for the melt flow rate of the polypropylene resin is: ISO 1133-1:2011.

[0014] Specifically, the mass percentage of the polypropylene resin in the present invention to the polypropylene composition is not less than 60%.

[0015] Preferably, the toughening agent is selected from one or more of ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene copolymer, and hydrogenated styrene-butadiene block copolymer.

[0016] Preferably, the melt flow rate of the toughener at 190°C and 2.16kg is 0.5-13g / 10min. Further preferably, the melt flow rate of the toughener at 190°C and 2.16kg is 5-13g / 10min. The melt flow rate of the toughener in the present invention can be 0.5g / 10min, 2.5g / 10min, 4.5g / 10min, 6.5g / 10min, 8.5g / 10min, 10.5g / 10min, 12.5g / 10min, etc., or an interval range formed by any of the above values, such as 0.5-6.5g / 10min, 10.5-13g / 10min, etc., and the present invention is not limited thereto. Specifically, the test method for the melt flow rate of the toughener is: ISO 1133-1:2011.

[0017] Preferably, the filler is selected from one or more of talc powder, calcium carbonate and mica powder.

[0018] Preferably, the auxiliary agent includes an antioxidant. Specifically, the antioxidant includes a primary antioxidant and a secondary antioxidant, the primary antioxidant is selected from hindered phenol antioxidants, and the secondary antioxidant is selected from phosphite antioxidants. Further, the primary antioxidant is selected from one or two of 2,6-di-tert-butyl-4-methylphenol and tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester. The secondary antioxidant is selected from one or two of tris[2.4-di-tert-butylphenyl]phosphite and bis(2,4-di-tert-butylphenol)pentaerythritol diphosphite.

[0019] Furthermore, the present invention also provides a method for preparing a polypropylene composition, which comprises mixing a polypropylene resin, a toughening agent, a filler, a polyether polyol and an auxiliary agent, melt-extruding and granulating the mixture to prepare the polypropylene composition.

[0020] Preferably, the temperature during the melt extrusion is 200-240°C.

[0021] Preferably, the screw speed during the melt extrusion is 400-450 rpm.

[0022] Furthermore, the present invention claims a use of the polypropylene composition in preparing an injection molded product with weakened pressure lines.

[0023] Specifically, the weakening of the pressure line refers to reducing the height of the protrusion of the pressure line. The injection molded product can be an automobile part. Specifically, the polypropylene composition can be used as an automobile interior material or exterior material in an instrument panel, door panel or bumper, etc., especially in situations where high requirements are placed on the appearance and flatness of the polypropylene composition.

[0024] Furthermore, the present invention seeks to protect an injection-molded product with a weakened pressure line, which is obtained by injection molding the above-mentioned polypropylene composition.

[0025] Preferably, during the injection molding process, the injection pressure is 35 to 45 Bar, and the holding pressure is 30 to 40 Bar.

[0026] Compared with the prior art, the present invention has the following beneficial effects: in the present invention, polyether polyol is added to the polypropylene composition, and when the polypropylene composition is injection molded into a product, different streams of the polypropylene composition converge at the intersection of holes or the intersection of streams, and the polyether polyol can prompt the different streams to quickly form cross-linking points, so that the different streams after cross-linking tend to be flat more quickly, thereby reducing the height of the pressure line protrusion of the product and improving the appearance of the product. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with the specification and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0028] Examples and Comparative Examples Raw Materials Description:

[0029] PP1: polypropylene resin, melt flow rate at 230°C and 2.16kg is 30g / 10min, PP EP548R, CNOOC and Shell.

[0030] PP2: polypropylene resin, melt flow rate at 230°C and 2.16kg is 10g / 10min, PP K9010, Formosa Chemical Corporation.

[0031] PP3: polypropylene resin, melt flow rate at 230°C and 2.16kg is 60g / 10min, PP BX3900, SK, Korea.

[0032] Toughener 1: ethylene-butene copolymer, melt flow rate at 190°C and 2.16 kg is 1.5 g / 10 min, POE ENGAGE 7467, DOW.

[0033] Toughener 2: ethylene-butene copolymer, melt flow rate at 190°C and 2.16 kg is 5 g / 10 min, POE ENGAGE 7447, DOW.

[0034] Toughener 3: ethylene-octene copolymer, melt flow rate at 190°C and 2.16 kg is 0.5 g / 10 min, POE ENGAGE 8842, DOW.

[0035] Toughener 4: ethylene-octene copolymer, melt flow rate at 190°C and 2.16 kg is 13 g / 10 min, POE ENGAGE 8137, DOW.

[0036] Filler: Talc, TYT-777A, Haicheng Tianyuan Chemical Co., Ltd.

[0037] Polyether triol 1: weight average molecular weight 1350, GO2280T, Arkema.

[0038] Polyether triol 2: weight average molecular weight 1000, TO2200, Arkema.

[0039] Polyether triol 3: weight average molecular weight 650, TO470, Arkema.

[0040] Polyether triol 4: weight average molecular weight 450, GO360, Arkema.

[0041] Crosslinking agent 1: vinyl triethoxysilane, A-151, Union Carbide, USA.

[0042] Cross-linking agent 2: dicumyl peroxide, Akzo Nobel.

[0043] Additives:

[0044] Primary antioxidant: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, commercially available.

[0045] Secondary antioxidant: tris[2,4-di-tert-butylphenyl]phosphite, commercially available.

[0046] Unless otherwise specified, the components (such as antioxidants, etc.) selected in the parallel examples and comparative examples are all the same commercially available products.

[0047] Example 1

[0048] The weight parts of the raw materials used in Example 1 are shown in Table 1.

[0049] A method for preparing a polypropylene composition, the specific steps comprising:

[0050] The polypropylene resin, filler, toughening agent, polyether polyol and auxiliary agent were weighed and mixed according to the weight parts in Table 1, and then melt-extruded in a twin-screw extruder (the melt extrusion temperature was 230° C. and the screw speed was 450 rpm), and granulated to obtain a polypropylene composition.

[0051] Embodiments 2 to 11

[0052] The weight parts of the raw materials used in the following examples are shown in Table 1.

[0053] The specific preparation steps of the following examples are the same as those of Example 1.

[0054] Comparative Examples 1 to 4

[0055] The weight parts of the raw materials used in the following comparative examples are shown in Table 2.

[0056] The specific preparation steps of each comparative example are the same as those of Example 1.

[0057] Table 1 is the formula components of each embodiment:

[0058] Table 1

[0059]

[0060]

[0061] Table 2 shows the formula components of each comparative example:

[0062] Table 2

[0063] Components Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 PP1 67 67 67 67 Toughener 1 10 10 10 0 filler 20 20 20 20 Polyether triol 1 0 0 0 3 Crosslinker 1 0 3 0 0 Crosslinker 2 0 0 3 0 Primary Antioxidant 0.2 0.2 0.2 0.2 Secondary antioxidant 0.2 0.2 0.2 0.2

[0064] The polypropylene compositions prepared in the above examples and comparative examples were tested according to the following test methods.

[0065] Height of pressure line protrusion: The polypropylene compositions prepared in the examples and comparative examples were injection molded into pressure line specimens using a KraussMaffei 200T injection molding machine with the injection pressure controlled at 40 Bar, the holding pressure at 35 Bar, and the time at 15 s. The pressure line protrusion heights of the pressure line specimens prepared in different comparative examples and examples were then observed under a microscope.

[0066] Table 3 and Table 4 are the performance test results of each embodiment and comparative example respectively.

[0067] Table 3

[0068]

[0069] Table 4

[0070] Test items Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Pressure line bulge height (um) 155 138 135 159

[0071] It can be seen from the data of the embodiment that after the polypropylene composition is prepared into a pressure line sample, the convex height of the pressure line is ≤65μm. Further preferably, the convex height of the pressure line is ≤32μm. The polypropylene composition provided by the present invention can prompt different streams to quickly form crosslinking points for crosslinking, thereby reducing the pressure when the streams meet, so that the different streams after crosslinking tend to be flat more quickly, thereby reducing the convex height of the pressure line of the product and improving the appearance of the product.

[0072] The results of Examples 1 and 7 to 9 show that the weight average molecular weight of the polyether polyol has a significant effect on the height of the pressure line protrusion of the product. The smaller the weight average molecular weight of the polyether polyol, the smaller the height of the pressure line protrusion of the product.

[0073] The results of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 show that when the polypropylene composition does not contain polyether polyol or other crosslinking agents are used to replace the polyether polyol in the polypropylene system, the height of the pressure line protrusion is difficult to achieve the desired effect of the present invention.

[0074] The results of Example 1 and Comparative Example 4 show that when the polypropylene composition does not contain a toughening agent, the height of the pressure line protrusion is difficult to achieve the desired effect of the present invention.

[0075] The foregoing examples are merely illustrative and are used to explain some features of the method of the present invention. The appended claims are intended to require the widest possible range that can be imagined, and the embodiments presented herein are demonstrated by the applicant's actual test results. Therefore, the applicant's intention is that the appended claims are not limited by the selection of examples that illustrate the features of the present invention. Some numerical ranges used in the claims also include sub-ranges therein, and changes in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A polypropylene composition, characterized in that The composition comprises the following components by weight: 49-71 parts of polypropylene resin, 8-13 parts of toughening agent, 15-25 parts of filler, 1-5 parts of polyether polyol, and 0-0.8 parts of auxiliary agent; The polyether polyol is a polyether triol; The weight average molecular weight of the polyether polyol is 450 to 1350; The toughening agent is selected from one or more of ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene copolymer, and hydrogenated styrene-butadiene block copolymer; The melt flow rate of the polypropylene resin at 230° C. and 2.16 kg is 10 to 60 g / 10 min; The melt flow rate of the toughening agent at 190° C. and 2.16 kg is 0.5 to 13 g / 10 min.

2. The polypropylene composition according to claim 1, characterized in that The filler is selected from one or more of talc powder, calcium carbonate and mica powder.

3. The method for preparing the polypropylene composition according to any one of claims 1 to 2, characterized in that: The polypropylene resin, toughening agent, filler, polyether polyol and auxiliary agent are mixed, melt-extruded and granulated to prepare the polypropylene composition.

4. Use of the polypropylene composition according to any one of claims 1 to 2 in the preparation of injection-molded products with weakened pressure lines.

5. An injection molded product with a weakened pressure line, characterized in that: The polypropylene composition according to any one of claims 1 to 2 is injection molded to obtain the injection molded product with weakened pressure line.

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