A tensile necking-resistant polypropylene composite material, a preparation method and application thereof

Abstract

The application discloses a kind of anti-stretch necking polypropylene composite material and its preparation method and application, belong to high polymer technical field.The anti-stretch necking polypropylene composite material of the application includes the following weight parts of component: polypropylene 82-96 parts, toughening agent 4-13 parts, compatible agent 0-8 parts, polyether 0-5 parts;The toughening agent is linear low density polyethylene, and the melt mass flow rate of the linear low density polyethylene under the condition of 190 DEG C, 2.16kg is 1-5g / 10min;The compatible agent is propylene-ethylene block copolymer.The yield elongation and bending part width of polypropylene composite material can be improved by selecting linear low density polyethylene as toughening agent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and particularly relates to a tensile necking-resistant polypropylene composite material and a preparation method and application thereof. BACKGROUND

[0002] Polypropylene has the advantages of low cost, good comprehensive performance, rich raw material resources, environmental protection, non-toxicity and easy recycling, and is often used as a raw material to be injection molded into different parts in automobile decoration and household appliances. However, the PP tubular part appears tensile necking when being bent, causing uneven fluctuations on the surface of the material and affecting the use of the part. In the prior art, the improvement is mainly aimed at the stress whitening resistance of PP. For example, the patent "Low-temperature bending whitening-resistant polypropylene composite material" improves the dispersibility of POE in the polypropylene matrix by using a mixed dispersant obtained by compounding polyvinyl alcohol and alkyl phenol polyoxyethylene ether, and improves the low-temperature bending whitening phenomenon of the polypropylene material. However, the low-temperature bending whitening resistance does not mean that the tensile necking resistance of the polypropylene is high. The patent "High-flow bending-resistant halogen-free flame-retardant glass fiber reinforced polypropylene composite material" improves the bending resistance of the composite material by adding an alpha nucleating agent, and improves the flowability of the composite material by adding a hyperbranched polymer. However, due to too many raw materials used in the patent, the processing is difficult, and the tensile necking resistance of the polypropylene composite material is poor. Nowadays, it is necessary to develop a polypropylene composite material with tensile necking resistance. SUMMARY

[0003] The application aims to overcome the shortcomings of the prior art, and provides a tensile necking-resistant polypropylene composite material and a preparation method and application thereof, which solve the problem of uneven fluctuations on the surface of the material caused by tensile necking of the PP tubular part when being bent, and affect the use of the part.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the application is as follows:

[0005] A tensile necking-resistant polypropylene composite material comprises the following components by weight: copolymerized polypropylene 82-96 parts, toughening agent 4-13 parts, compatibilizer 0-8 parts, and polyether 0-5 parts. The toughening agent is linear low-density polyethylene, and the melt mass flow rate of the linear low-density polyethylene is 1-5 g / 10 min at 190 DEG C and under a load of 2.16 kg. The compatibilizer is a propylene-ethylene block copolymer.

[0006] The necking problem is caused by the slippage between molecular chains during the stretching of the polypropylene material, and the yield elongation is the key factor for controlling the necking, the greater the yield elongation, the longer the elastic stage of the material, and the later the necking occurs, so improving the yield elongation of the material is the key point for improving the necking phenomenon. In the anti-stretching necking polypropylene composite material of the present application, the addition of the toughening agent can improve the yield elongation and the width of the bending part of the polypropylene composite material. When the melt mass flow rate of the linear low density polyethylene is within the above range, the molecular weight distribution of the linear low density polyethylene is narrow, the structure is regular, and the mechanical properties are good, which can effectively improve the mechanical properties and anti-stretching necking properties of the polypropylene composite material. The melt mass flow rate of the linear low density polyethylene is one of the key factors affecting the performance of the product, and if the melt mass flow rate of the linear low density polyethylene is too high, the mechanical properties and anti-stretching necking properties of the product will decrease significantly. If homopolypropylene is used to replace copolypropylene, the anti-stretching necking properties of the obtained product are good, but other properties of the product cannot meet the requirements, among which the impact properties, especially the low-temperature impact properties, are mainly affected.

[0007] The present application improves the compatibility between polypropylene and toughening agent by selecting propylene-ethylene block copolymer as a compatibilizer, further improves the yield elongation and bending part width of the polypropylene composite material. In addition, polyether is a linear polymer prepared by ring-opening homopolymerization or copolymerization of monomers such as ethylene oxide, propylene oxide and butylene oxide under the action of a catalyst; the inventors found that the addition of polyether to the system can improve the softness of the polypropylene composite material chain segment, thereby further improving the yield elongation and bending part width of the polypropylene composite material and improving the stretching necking phenomenon of the polypropylene material.

[0008] The copolymerized polypropylene in the melt flow rate range commonly sold in the market can be used in the present application, and optionally, the melt mass flow rate of the copolymerized polypropylene is 1-20 g / 10 min under the condition of 230℃ and 2.16 kg.

[0009] It should be noted that the melt mass flow rate of the copolymerized polypropylene in the present application is tested according to the method of ISO 1133-2011.

[0010] As a preferred embodiment of the anti-stretching necking polypropylene composite material of the present application, the content of the toughening agent is 8-12 parts by weight.

[0011] The inventors of the present application found through further research that the content of the toughening agent is an important factor affecting the polypropylene composite material; if the content of the toughening agent is too small, the yield elongation and bending part width of the polypropylene composite material are improved to a low degree; if the content of the toughening agent is too large, the beneficial effects of the product will not be further improved, and even decreased.

[0012] As a preferred embodiment of the anti-stretch neck polypropylene composite material, the content of the polyether is 2-3 parts by weight; the content of the compatilizer is 3-5 parts by weight.

[0013] As a preferred embodiment of the anti-stretch neck polypropylene composite material, the average molecular weight of the polyether is 1100-9000; preferably, the average molecular weight of the polyether is 2000-8350.

[0014] In the present application, the test method of the average molecular weight of the polyether comprises the following steps: the polyether is added into 1,2,4-trichlorobenzene and completely dissolved at a temperature of 145℃, to prepare a solution with a concentration of 2mg / mL, and the obtained solution is tested on a high temperature gel chromatograph equipped with an ultraviolet detector, at a elution rate of 1mL / min.

[0015] In the polypropylene composite material, the addition amount or molecular weight of the polyether also affects the performance of the polypropylene composite material, for example, if the addition amount of the polyether is too large, the beneficial effect of the product is not obviously increased. If the molecular weight of the polyether is too small, the yield elongation and the width of the bending part of the product cannot be obviously improved.

[0016] As a preferred embodiment of the anti-stretch neck polypropylene composite material, the density of the propylene-ethylene block copolymer is 0.879-0.910g / cm 3 ; the melt mass flow rate of the propylene-ethylene copolymer is 1-30g / 10min under the condition of 230℃ and 2.16kg. Preferably, the density of the propylene-ethylene block copolymer is 0.88-0.89g / cm 3 .

[0017] It should be noted that the melt mass flow rate of the propylene-ethylene block copolymer in the present application is tested according to the method of ISO1133-2011.

[0018] As a preferred embodiment of the anti-stretch neck polypropylene composite material, the density of the linear low density polyethylene is 0.910-0.930g / cm 3 .

[0019] The test standard of the density of the propylene-ethylene block copolymer and the density of the linear low density polyethylene in the present application is ISO 1183-2019, and the test condition is 23℃.

[0020] As a preferred embodiment of the anti-stretch neck polypropylene composite material, the anti-stretch neck polypropylene composite material further comprises 0.5-2 parts by weight of black color masterbatch and 0.2-0.8 parts by weight of antioxidant.

[0021] As a preferred embodiment of the anti-stretch necking polypropylene composite material of the present application, the antioxidant is a primary antioxidant and a secondary antioxidant; the primary antioxidant is a hindered phenol; and the secondary antioxidant is a phosphite.

[0022] In the present application, the primary antioxidant and the secondary antioxidant are added to improve the stability of the polypropylene composite material. Optionally, the mass ratio of the primary antioxidant to the secondary antioxidant is 1:1.

[0023] Another object of the present application is to provide a preparation method of the anti-stretch necking polypropylene composite material, comprising the following steps: uniformly mixing the components in proportion, and then melt-extruding and granulating at 180-220°C to obtain the anti-stretch necking polypropylene composite material.

[0024] Preferably, the mixing is carried out in a high-speed mixer, and the rotation speed of the high-speed mixer is 700-800 rpm.

[0025] Preferably, the extrusion is carried out in a twin-screw extruder, and the rotation speed of the twin-screw extruder is 400-450 rpm, and the length-diameter ratio of the twin-screw extruder is 48:1.

[0026] Still another object of the present application is to provide the application of the anti-stretch necking polypropylene composite material in the preparation of automobile parts.

[0027] Preferably, the automobile parts are automobile brake pipelines and cooling pipelines.

[0028] Compared with the prior art, the present application has the following beneficial effects: by selecting linear low-density polyethylene as a toughening agent, the toughness of the polypropylene composite material is improved, and the necking problem of the polypropylene material is solved. The notched impact strength of the polypropylene composite material of the present application is 57-78 KJ / m 2 , the flexural modulus is 907-1050 MPa, the yield elongation is 9.5-18.8%, and the width of the bending part is 673-865 μm. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the necking evaluation method of the present application. DETAILED DESCRIPTION

[0030] In order to better illustrate the purpose, technical scheme and advantages of the present application, the present application will be further described below in combination with specific examples and drawings, the purpose of which is to understand the content of the present application in detail, rather than to limit the present application. All other examples obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application. The experimental reagents and instruments involved in the implementation of the present application are common ordinary reagents and instruments unless otherwise specified.

[0031] The raw materials used in the examples and comparative examples are described as follows, but are not limited to these materials:

[0032] Polypropylene:

[0033] PP-1 : Copolymerized polypropylene, PP 3010, melt flow rate of 1.5 g / 10 min at 230°C under a load of 2.16 kg, density of 0.90 g / cm 3 , purchased from Taiwan Chemical Fibre Co., Ltd.;

[0034] PP-2: Copolymerized polypropylene, PP K9010, melt flow rate of 10.0 g / 10 min at 230°C under a load of 2.16 kg, density of 0.90 g / cm 3 , purchased from Taiwan Chemical Fibre Co., Ltd.;

[0035] PP-3: Copolymerized polypropylene, PP K9017, melt flow rate of 17.0 g / 10 min at 230°C under a load of 2.16 kg, density of 0.90 g / cm 3 , purchased from Taiwan Chemical Fibre Co., Ltd.;

[0036] Toughener 1: Linear low-density polyethylene, LLDPE EXCEED 3518PA, melt flow rate of 3.5 g / 10 min at 190°C under a load of 2.16 kg, density of 0.913 g / cm 3 , purchased from ExxonMobil;

[0037] Toughener 2: Linear low-density polyethylene, LLDPE 5220G, melt flow rate of 3.5 g / 10 min at 190°C under a load of 2.16 kg, density of 0.915 g / cm 3 , purchased from DOW;

[0038] Toughener 3: Linear low-density polyethylene, LLDPE HP3518CN, melt flow rate of 4.5 g / 10 min at 190°C under a load of 2.16 kg, density of 0.918 g / cm 3 , purchased from LG Chemical;

[0039] Toughener 4: Linear low-density polyethylene, LLDPE DFDA-7042 (ZHENHAI), melt flow rate of 1.5 g / 10 min at 190°C under a load of 2.16 kg, density of 0.915 g / cm 3 , purchased from Zhenhai Refinery;

[0040] Toughener 5: Linear low density polyethylene, LLDPE M2320, melt flow rate at 190°C, 2.16 kg load of 20 g / 10 min, density of 0.913 g / cm 3 , purchased from SINOPEC;

[0041] Toughener 6: Ethylene-butene copolymer, POE ENGAGE 7467, melt flow rate at 190°C, 2.16 kg load of 1.3 g / 10 min, density of 0.862 g / cm 3 , purchased from DOW;

[0042] Toughener 7: Low density polyethylene, LDPE 2426H, melt flow rate at 190°C, 2.16 kg load of 1.9 g / 10 min, density of 0.925 g / cm 3 , purchased from CNOOC SHELL;

[0043] Compatibilizer 1: Propylene-ethylene block copolymer, PE D5535.00, melt flow rate at 230°C, 2.16 kg load of 6.5 g / 10 min, density of 0.879 g / cm 3 , purchased from DOW;

[0044] Compatibilizer 2: Propylene-ethylene block copolymer, PE D5545.00, melt flow rate at 230°C, 2.16 kg load of 9.5 g / 10 min, density of 0.905 g / cm 3 , purchased from DOW;

[0045] Polyether 1: Polyether L31, average molecular weight of 1100, purchased from Nantong Chenrun Chemical Co., Ltd.;

[0046] Polyether 2: Polyether L61, average molecular weight of 2000, purchased from Nantong Chenrun Chemical Co., Ltd.;

[0047] Polyether 3: Polyether L38, average molecular weight of 5000, purchased from Nantong Chenrun Chemical Co., Ltd.;

[0048] Polyether 4: Polyether L68, average molecular weight of 8350, purchased from Nantong Chenrun Chemical Co., Ltd.;

[0049] Black color masterbatch: PE2772KF, density of 1.2 g / cm 3 , melt mass flow rate at 190°C, 21.6 kg load of 27 g / 10 min, purchased from CABOT;

[0050] Primary antioxidant: Hindered phenol, antioxidant 1010, purchased from BASF;

[0051] Secondary antioxidant: Phosphite, antioxidant 168, purchased from BASF.

[0052] Examples 1-20 and Comparative Examples 1-5

[0053] The components and weight parts of the tensile necking-resistant polypropylene composite materials of the examples and comparative examples are shown in Tables 1 and 2, wherein the preparation method of the tensile necking-resistant polypropylene composite materials of Examples 1-20 and Comparative Examples 1-5 comprises the following steps:

[0054] The components were added into a high-speed mixer in the proportions shown in Tables 1 and 2, and mixed at a speed of 700 rpm. After uniform mixing, the mixture was obtained. Then, it was added to a twin-screw extruder, and melt-extruded, granulated at 180-220°C (Zone 1: 80°C, Zone 2: 180°C, Zone 3: 200°C, Zone 4: 200°C, Zone 5: 210°C, Zone 6: 220°C, Zone 7: 220°C, Zone 8: 220°C) at a speed of 450 r / min, to obtain the tensile necking-resistant polypropylene composite material.

[0055] Table 1 Content of each component in the tensile necking-resistant polypropylene composite material of Examples 1-12 (weight parts)

[0056]

[0057] Table 2 Content of each component in the tensile necking-resistant polypropylene composite material of Examples 13-20 and Comparative Examples 1-5 (weight parts)

[0058]

[0059] Performance test:

[0060] The polypropylene composite materials prepared in the above examples and comparative examples were injection molded to obtain ISO mechanical samples. After injection molding, the ISO mechanical samples were conditioned in a standard environment (23°C, 50% relative humidity) for 24 hours, and then the performance test was performed. The specific test items and methods are as follows:

[0061] 1. Yield elongation: The sample was injection molded to meet the test requirements of ISO 527-2012 standard (the sample was type 1A, and the sample thickness was 4 mm). The test was performed using a German ZWICK / Z010 universal material testing machine under the conditions of a test rate of 50 mm / min, a clamp distance of 115 mm, and a test temperature of 23°C.

[0062] 2. Bending modulus: The sample was injection molded to meet the test requirements of ISO 178-2014 standard bending modulus (the sample parameters were: 80x10x4 mm). The test was performed under the conditions of a test speed of 2 mm / min and a test temperature of 23°C.

[0063] 3. Notched impact strength: the polypropylene composite material prepared in the above examples and comparative examples was injection molded into a sample bar (sample bar parameters: 80 x 8 x 4 mm, A-type notch) in accordance with the requirements of the notched impact strength test of ISO 179-2010 standard, and the test was performed at a test temperature of 23°C using a ZWICK 5.5P pendulum impact testing machine.

[0064] 4. Necking evaluation method: the polypropylene composite material prepared in the above examples and comparative examples was injection molded into a part, and then the part was bent, the width of the necking part after bending was tested, and the severity of necking was evaluated according to the width, the smaller the width, the more serious the necking (as shown in the following table). Figure 1

[0065] The test results are shown in Table 3.

[0066] Table 3 Performance test results

[0067]

[0068]

[0069] As can be seen from Table 3, the polypropylene composite material has high mechanical properties (notched impact strength > 59 KJ / m 2 , bending modulus > 810 MPa), and also has excellent tensile necking resistance (yield elongation > 11.5%, bending part width > 710 μm).

[0070] As can be seen from Comparative Example 1-2, the yield elongation and bending part width of the product are at a relatively low level, indicating that the tensile necking problem of the polypropylene is serious without the addition of a toughening agent.

[0071] As can be seen from Comparative Example 1-3, the melt flow rate of the polypropylene has a certain influence on the performance of the product, the tensile necking resistance of the product is increased to a certain extent, and the mechanical properties are slightly decreased.

[0072] As can be seen from the comparison of Comparative Example 1-5, Example 1-2 and Example 4-6, the type of toughening agent will affect the mechanical properties and tensile necking resistance of the product, when the toughening agent is linear low density polyethylene, the obtained product has good tensile necking resistance; and the melt flow rate of the linear low density polyethylene has a certain influence on the mechanical properties and tensile necking resistance of the product, the melt flow rate of the linear low density polyethylene in the product of Comparative Example 3 is relatively high, and the mechanical properties and tensile necking resistance of the obtained product are significantly decreased.

[0073] ​From the comparison of Example 1 and Examples 7-9, it can be seen that the content of the toughening agent has certain influence on the performance of the product, too little content of the toughening agent, the improvement of the yield elongation and the width of the bending part of the product is not obvious; too much content of the toughening agent, the beneficial effect of the product is not obviously increased.

[0074] From the comparison of Example 1, Examples 10-12 and Example 20, it can be seen that the addition of the compatilizer or the polyether can further improve the toughness and the tensile necking resistance of the product.

[0075] From the comparison of Example 10 and Examples 13-19, it can be seen that the polyether can significantly improve the mechanical properties and the tensile necking resistance of the product, especially when the average molecular weight of the polyether is 2000-8350, the mechanical properties and the tensile necking resistance of the product are obviously increased, when the content of the polyether reaches 2 parts, further increasing the content of the polyether, the mechanical properties and the tensile necking resistance of the product are not obviously improved.

[0076] Finally, it should be noted that the above examples are used to illustrate the technical solutions of the present application, but not to limit the protection scope of the present application, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced with the same, without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A stretch neck resistant polypropylene composite material, characterized in that, The components include the following parts by weight: copolymerized polypropylene 82-96 parts, toughening agent 4-13 parts, compatibilizer 0-8 parts, polyether 1-5 parts; the toughening agent is linear low density polyethylene, the melt mass flow rate of the linear low density polyethylene is 1-5 g / 10 min under the condition of 190 DEG C, 2.16 kg; the compatibilizer is propylene-ethylene block copolymer; the average molecular weight of the polyether is 1100-9000.

2. The neck-stretch-resistant polypropylene composite of claim 1, wherein, The content of the toughening agent is 8-12 parts by weight.

3. The neck-stretch-resistant polypropylene composite of claim 1, wherein, The content of the polyether is 2-3 parts by weight; the content of the compatibilizer is 3-5 parts by weight.

4. The neck-stretch-resistant polypropylene composite of claim 1, wherein the polypropylene is a homopolymer of propylene. The average molecular weight of the polyether is 2000-8350.

5. The neck-stretch-resistant polypropylene composite of claim 1, wherein, The propylene-ethylene block copolymer has a density of 0.879 to 0.910 g / cm 3 ; and a melt mass-flow rate of 1 to 30 g / 10 min at 230 °C, 2.16 kg.

6. The neck-stretch-resistant polypropylene composite of claim 1, wherein, The linear low density polyethylene has a density of 0.910 to 0.930 g / cm 3 .

7. The neck-stretch-resistant polypropylene composite of claim 1, wherein the polypropylene is a homopolymer of propylene. The anti-stretching necking polypropylene composite material further includes 0.5-2 parts by weight of black color masterbatch and 0.2-0.8 parts by weight of antioxidant.

8. The neck-stretch-resistant polypropylene composite of claim 7, wherein the polypropylene is a homopolymer of propylene. The antioxidant is primary antioxidant and secondary antioxidant; the primary antioxidant is hindered phenol; the secondary antioxidant is phosphite.

9. A process for the production of the tensile necking resistant polypropylene composite according to any one of claims 1 to 8, characterized in that, The method includes the following steps: after mixing the components uniformly according to the proportion, melt extruding and granulating under 180-220 DEG C to obtain the anti-stretching necking polypropylene composite material.

10. The use of the anti-stretching necking polypropylene composite material according to any one of claims 1-8 in the preparation of automobile parts.

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