Polypropylene composition as well as preparation method and application thereof

Abstract

The invention discloses a polypropylene composition, and belongs to the field of high polymer materials and technologies. Specifically, the polypropylene composition provided by the invention comprises the following components: 29-61 parts of polypropylene; 1 to 8 parts of maleic anhydride grafted polypropylene; 5 to 25 parts of acrylate elastomer; 1-6 parts of an azo initiator; and 35-45 parts of glass fiber. The polypropylene composition disclosed by the invention has the advantages of high strength, high weather resistance and color change resistance, and can be applied to preparation of water purification processor parts.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and technology, and in particular relates to a polypropylene composition and a preparation method thereof. Background Art

[0002] Polypropylene (PP) is a polymer compound made from propylene. The main characteristics of PP materials are low density, light weight, good insulation, corrosion resistance, wear resistance and impact resistance. In addition, PP has a high melting point, so it can withstand higher operating temperatures. These characteristics make PP materials have excellent performance in packaging, medical, construction, home appliances, automobiles and other fields.

[0003] However, PP materials also face some challenges during their application. For example, factors such as ultraviolet radiation, high temperature environment and chemical corrosion may cause problems such as material discoloration and performance degradation.

[0004] Chinese invention patent CN115010920A discloses a high melt strength polypropylene and its preparation method. The high melt strength polypropylene is obtained by a synthetic reaction between polypropylene and a hyperbranched crosslinking agent. The crosslinking degree of the high melt strength polypropylene can be controlled, the formation of gel can be controlled, and the problem of reduced material processing performance caused by the formation of gel can be avoided. While improving the melt strength, the overall structural strength is enhanced, but there is no mention of improving the color change problem.

[0005] Chinese invention patent CN102532701A discloses a low-warpage, creep-resistant polypropylene composition and its preparation method, which uses a compatibilizer and a nucleating agent to improve the creep resistance and warpage performance of polypropylene. The invention can improve the overall creep performance of the material, thereby improving its structural strength, but the improvement is not enough, and the problem of cracking still occurs at 23°C and 6 bar pressure.

[0006] Therefore, the prior art lacks a polypropylene composition having high compressive strength and being not easy to discolor. Summary of the invention

[0007] The object of the present invention is to overcome the above technical problems and provide a polypropylene composition with high strength, high weather resistance and color change resistance.

[0008] Another object of the present invention is to provide a method for preparing the polypropylene composition.

[0009] Another object of the present invention is to provide application of the polypropylene composition.

[0010] The present invention is achieved through the following technical solutions: A polypropylene composition, comprising the following components by weight: Polypropylene 29-61 parts; Maleic anhydride grafted polypropylene 1-8 parts; 5-25 parts of acrylic elastomer; 1-6 parts of azo initiator; Glass fiber 35-45 parts; Wherein, the polypropylene is selected from homopolypropylene.

[0011] Preferably, the melt mass flow rate of the polypropylene is 5-30 g / 10 min, and the testing conditions are: 230° C., 2.16 kg.

[0012] In the present invention, the mass percentage of the polypropylene in the polypropylene composition is not less than 29%.

[0013] Preferably, the melt mass flow rate of the maleic anhydride grafted polypropylene is 80-140 g / 10 min, the testing conditions are: 190° C., 2.16 kg, and the testing standard is: ISO 1133-1:2022.

[0014] Preferably, the density of the maleic anhydride grafted polypropylene is 0.900-0.915 g / cm 3 , grafting rate 0.8-1.2%.

[0015] Maleic anhydride grafted polypropylene as a compatibilizer can improve the compatibility of polypropylene and glass fiber.

[0016] Preferably, the butyl acrylate content in the acrylic elastomer is 17-30wt%; Further preferably, the butyl acrylate content in the acrylic elastomer is 20-30wt%.

[0017] Specifically, the acrylic elastomer can be selected from: ethylene-methacrylic acid-butyl acrylate terpolymer and zinc ion ionomer, ethylene-methacrylic acid-butyl acrylate terpolymer, ethylene-butyl acrylate-glycidyl methacrylate terpolymer or ethylene-butyl acrylate copolymer.

[0018] Acrylic elastomers have a certain improvement on the weather resistance of polypropylene compositions, and the improvement on burst pressure performance is more obvious. Butyl acrylate in acrylic elastomers can increase the degree of cross-linking of polypropylene molecular chains during processing, causing the system to form a more complex network structure, thereby improving the structural strength of the polypropylene composition.

[0019] According to the test results, the bursting pressure of the polypropylene composition can be increased by increasing the addition amount of acrylic elastomer, but the higher the addition amount of acrylic elastomer is, the better. After reaching a certain upper limit, the effect of increasing the bursting pressure of the polypropylene composition gradually weakens, and continuing to increase the addition amount of acrylic elastomer has no change on the bursting pressure.

[0020] The test results further show that as the butyl acrylate content in the acrylic elastomer increases, the bursting pressure of the polypropylene composition increases.

[0021] Preferably, the molecular weight of the azo initiator is 150-300; More preferably, the molecular weight of the preferred azo initiator is 200-300.

[0022] The molecular weight of azo initiators has a great influence on the entanglement of molecular chains, thus affecting the bursting pressure.

[0023] The composite material changes color because the antioxidant generates by-product anthraquinone substances when it takes effect. This substance itself is yellow. The present invention can neutralize the anthraquinone substances generated during the antioxidant processing by adding an azo initiator, thereby reducing the yellow substance and further improving the problem of discoloration.

[0024] According to the test results, the color change of the polypropylene composition decreases with the increase of the azo initiator content. However, continuing to increase the azo initiator content after reaching the upper limit is likely to cause material degradation. After the material is degraded, the molecular chain breaks, the performance drops sharply, and the material becomes powdery.

[0025] Preferably, the processing aid includes a primary antioxidant and a secondary antioxidant.

[0026] Preferably, the primary antioxidant is selected from hindered phenols, and the secondary antioxidant is selected from phosphites.

[0027] Those skilled in the art can add 0-5 parts of auxiliary agents by weight according to actual needs.

[0028] Preferably, the auxiliary agent is selected from: 0-2 parts of colorant; 0-1 parts of antioxidant; 0-1 parts of light stabilizer.

[0029] Preferably, the colorant can be added in the form of masterbatch.

[0030] The present invention also provides a method for preparing the above-mentioned polypropylene composition, comprising the following steps: weighing each component except the azo initiator according to weight, putting it into a high-speed stirrer and mixing it evenly to obtain a mixture; adding the mixture into a twin-screw extruder, adding the azo initiator through side feeding, melt-kneading, extruding and granulating to obtain a polypropylene composition.

[0031] Preferably, the melt mixing temperature is 180-210° C., and the screw speed is 450-500 rpm.

[0032] The present invention also provides application of the polypropylene composition for preparing water purification processor components.

[0033] The present invention has the following beneficial effects: Compared with the prior art, the present invention improves the bursting pressure performance of the polypropylene composition by adding an acrylic elastomer; at the same time, by adding an azo initiator, anthraquinone substances appearing during the processing and use of the antioxidant can be neutralized, thereby improving discoloration. The polypropylene composition provided by the present invention has good pressure resistance, weather resistance and anti-discoloration performance. DETAILED DESCRIPTION

[0034] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0035] The raw materials used in the present invention come from: Polypropylene 1: M1200HS, homopolypropylene, with a melt mass flow rate of 5-15 g / 10 min at 230° C. and 2.16 kg load, purchased from Sinopec.

[0036] Polypropylene 2: Z30S, homopolypropylene, with a melt mass flow rate of 10-30 g / 10 min at 230° C. and 2.16 kg load, purchased from Sinopec.

[0037] Polypropylene 3: SP179 (Lanhua), copolymer polypropylene, with a melt mass flow rate of 5-15 g / 10 min at 230° C. and 2.16 kg load, purchased from Sinopec.

[0038] Maleic anhydride grafted polypropylene: BONDYRAM 1001CN, having a melt volume flow rate of 80-140 g / 10 min at 190° C. and 2.16 Kg load, purchased from Polyram.

[0039] Glass fiber: ECS13-4.5-T538D, monofilament diameter 13 μm, short cut length 4.0-5.5 mm, purchased from Taishan Glass Fiber Co., Ltd.

[0040] Acrylic elastomer 1: Surlyn® 9320, ethylene-methacrylic acid-butyl acrylate terpolymer and zinc ion ionomer, butyl acrylate content 23%, purchased from DuPont.

[0041] Acrylic elastomer 2: Elvaloy AC3117, ethylene-methacrylic acid-butyl acrylate terpolymer, butyl acrylate content 17%, purchased from Dow.

[0042] Acrylic elastomer 3: LOTADER® AX8750, ethylene-butyl acrylate-glycidyl methacrylate terpolymer, butyl acrylate content 25%, purchased from Arkema.

[0043] Acrylic elastomer 4: Elvaloy@AC 3427, ethylene-butyl acrylate copolymer, butyl acrylate content 27%, purchased from DuPont.

[0044] Azo initiator 1: PERKADOX AIBN, molecular weight about 164.2, purchased from Nouryon.

[0045] Azo initiator 2: PERKADOX AMBN, molecular weight about 192.3, purchased from Nouryon. Azo initiator 3: 1,1'-azo(cyanocyclohexane) PERKADOX ACCN, molecular weight about 244.3, purchased from Nouryon.

[0046] Colorant: PLASBLAK® PE2772KF, purchased from CABOT.

[0047] Antioxidant 1: SONOX 1010, hindered phenol, purchased from Shandong Linyi Sanfeng Chemical Co., Ltd.

[0048] Antioxidant 2: SONOX 168, phosphite, purchased from Shandong Linyi Sanfeng Chemical Co., Ltd.

[0049] Various test methods: (1) Color change test: The comparative example and the embodiment were directly injection molded into a 100*100*3 mm square plate, and tested for 2 cycles according to the PV3930 standard. The gray card grade and △E data were evaluated after 3200 hours. The gray card grade is used to reflect the level of material color change, and △E reflects the color difference. In the present invention, the gray card grade is required to be ≥4 and △E ≤3.2.

[0050] (2) Pressure resistance test: The examples and comparative examples were injection molded into finished products, and then subjected to a static pressure test at room temperature 23°C, and the pressure at which the parts burst was recorded.

[0051] Table 1 Weight parts of each component of polypropylene composition of Examples 1-12 and test results

[0052] It can be seen from Examples 1-12 that the gray card grade of the polypropylene composition provided by the present invention is ≥4, the bursting pressure is ≥6 Bar, and ΔE is ≤3.2.

[0053] Table 2 Weight parts of each component of the polypropylene composition of Comparative Examples 1-4 and test results

[0054] It can be seen from Comparative Example 1 that without adding acrylic elastomer and azo initiator, the gray card grade is reduced to 3, ΔE>3.2, and the burst pressure is <6. The polypropylene composition does not achieve high compressive strength and is not easy to change color.

[0055] It can be seen from Comparative Example 2 that the color difference of the polypropylene composition without adding azo initiators changes significantly.

[0056] It can be seen from Comparative Example 3 that increasing the amount of azo initiator added will cause material degradation. After the material is degraded, the molecular chain breaks and the performance drops sharply.

[0057] It can be seen from Comparative Example 4 that when copolymer polypropylene is used instead of homopolymer polypropylene, its bursting pressure is only 4.5 Bar, which cannot meet the pressure resistance requirement of the material.

Claims

1. A polypropylene composition, characterized in that By weight, it includes the following components Polypropylene 29-61 parts; Maleic anhydride grafted polypropylene 1-8 parts; 5-25 parts of acrylic elastomer; 1-6 parts of azo initiator; Glass fiber 35-45 parts; Wherein, the polypropylene is selected from homopolypropylene.

2. The polypropylene composition according to claim 1, characterized in that The melt mass flow rate of the polypropylene is 5-30 g / 10 min, and the testing conditions are: 230° C., 2.16 kg.

3. The polypropylene composition according to claim 1, characterized in that The density of the maleic anhydride grafted polypropylene is 0.900-0.915 g / cm 3 , grafting rate 0.8-1.2%.

4. The polypropylene composition according to claim 1, characterized in that The butyl acrylate content in the acrylic elastomer is 17-30wt%, preferably 20-30wt%.

5. The polypropylene composition according to claim 1, characterized in that The molecular weight of the azo initiator is 150-300, preferably 200-300.

6. The polypropylene composition according to claim 1, characterized in that The antioxidant comprises a primary antioxidant and a secondary antioxidant, wherein the primary antioxidant is selected from hindered phenols, and the secondary antioxidant is selected from phosphites.

7. The polypropylene composition according to claim 1, characterized in that By weight, the invention further comprises 0-5 parts of auxiliary agents; the auxiliary agents are preferably 0-2 parts of colorants; 0-1 parts of antioxidants; and 0-1 parts of light stabilizers.

8. The method for preparing a polypropylene composition according to any one of claims 1 to 8, characterized in that The method comprises the following steps: weighing each component except the azo initiator according to weight, putting the components into a high-speed stirrer and mixing them evenly to obtain a mixture; adding the mixture into a twin-screw extruder, adding the azo initiator through side feeding, melting and mixing, extruding and granulating to obtain a polypropylene composition.

9. Use of the polypropylene composition according to any one of claims 1 to 8, characterized in that Used to prepare water purification processor components.

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