Modified polypropylene material and its preparation method and application

Abstract

The present application provides a modified polypropylene material and its preparation method and application, wherein the material comprises: 40-75% copolymer PP, 10-30% homopolymer PP, 3-20% toughening agent, 1-5% scratch resistant agent, 0.2-5% compatibilizer, 1-3% titanium dioxide, 0.2-2% lubricant, 0.2-1.5% light stabilizer, and 0.2-1.5% antioxidant. The freezer lining prepared by the material solves the problem that the freezer lining is prone to warping and deformation. The preparation method of the modified polypropylene material provided by the present application can optimize the performance of copolymer PP and homopolymer PP to obtain better low-temperature impact resistance and rigidity. The freezer lining prepared by the material is lower in cost than the freezer lining prepared by ABS material, is suitable for industrial application, and has outstanding application effect.

Description

Technical Field

[0001] The present application relates to the field of polymer materials, and in particular to a modified polypropylene material and a preparation method and application thereof. Background Art

[0002] The lining of the freezer uses an integral injection molding structure of acrylonitrile butadiene styrene (ABS). Special structural requirements will use a splicing structure of ABS injection molding and PVC extrusion. Due to cost limitations, the ABS used in the lining is generally a conventional ABS brand.

[0003] The freezer is assembled from an outer shell and a lining. The outer shell of the freezer is made of metal, which has a small thermal expansion and contraction coefficient. The lining is made of plastic, which has a large thermal expansion and contraction coefficient. During the use of the freezer, the thermal expansion and contraction coefficients of the two materials, metal and plastic, differ greatly, and the corners or weak parts of the plastic lining are prone to cracking. In addition, the foaming material system of the freezer tends to be a multi-component foaming system, which has a lower thermal conductivity, but the chemical corrosion of the multi-component foaming material system is higher than that of the cyclopentane system. The ABS material has poor resistance to the chemical corrosion of the multi-component foaming system, and the lining is prone to chemical corrosion cracking.

[0004] Polypropylene (PP) material has the advantages of low density, good heat resistance, low cost, good chemical corrosion resistance, etc. It is also resistant to folding and not easy to break. If PP lining is used, the physical stress cracking and chemical corrosion cracking of the lining can be improved, and the cost of the parts can be reduced.

[0005] However, due to the large shrinkage rate of PP material, the large size of the freezer lining, and the special structure, the large shrinkage rate can easily cause the PP lining parts to warp and deform. In addition, PP material has poor low-temperature resistance and its surface hardness is worse than that of ABS material, which also limits the application of PP material in freezer linings. Summary of the invention

[0006] The present application provides a modified polypropylene material and a preparation method and application thereof, so as to solve the problem of warping and deformation of linings made of PP material.

[0007] In the first aspect, the present application provides a modified polypropylene material, which includes: 40-75% copolymer PP, 10-30% homopolymer PP, 3-20% toughening agent, 1-5% scratch resistant agent, 0.2-5% compatibilizer, 1-3% titanium dioxide, 0.2-2% lubricant, 0.2-1.5% light stabilizer, and 0.2-1.5% antioxidant.

[0008] Optionally, the copolymer PP has a melt mass flow rate greater than 10 g / 10 min at 230° C. and a load of 2.16 kg.

[0009] Optionally, the copolymer PP has an Izod notched impact strength greater than 6 Kj / m 2 .

[0010] Optionally, the melt mass flow rate of the homopolymer PP at 230° C. and a load of 2.16 kg is greater than 2 g / 10 min.

[0011] Optionally, the homopolymer PP has an Izod notched impact strength greater than 3 Kj / m 2 .

[0012] Optionally, the toughening agent is any one or more combinations of ethylene propylene diene monomer rubber EPDM and polyolefin elastomer POE.

[0013] Optionally, the anti-scratch agent is silicone masterbatch.

[0014] In a second aspect, the present application provides a method for preparing the modified polypropylene material according to the first aspect, comprising:

[0015] Add copolymer PP, homopolymer PP, toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant into a high-speed mixer and mix for 3-5 minutes to obtain a mixture;

[0016] The mixture is added into a twin-screw extruder and extruded into pellets to obtain a modified polypropylene material.

[0017] Optionally, the temperature range of the twin-screw extruder is 180-220° C., and the screw speed range of the twin-screw extruder is 300-500 rpm / min.

[0018] In a third aspect, the present application provides the use of the modified polypropylene material described in the first aspect in a freezer lining.

[0019] The present application provides a modified polypropylene material and its preparation method and application, wherein the material comprises: 40-75% copolymer PP, 10-30% homopolymer PP, 3-20% toughening agent, 1-5% scratch resistant agent, 0.2-5% compatibilizer, 1-3% titanium dioxide, 0.2-2% lubricant, 0.2-1.5% light stabilizer, and 0.2-1.5% antioxidant. The freezer lining prepared by the material solves the problem of warping and deformation of the freezer lining. It can obtain better assembly performance with the metal shell, and the freezer lining prepared by the material has qualified appearance after high and low temperature tests, without cracking and the like.

[0020] The preparation method of the modified polypropylene material provided in the present application can optimize the performance of copolymer PP and homopolymer PP to obtain better low-temperature impact resistance and rigidity. The preparation method is not only simple in process, but also easy to scale up production, and has industrial application prospects.

[0021] The modified polypropylene material provided in the present application has a lower cost for a freezer lining made from the material than a freezer lining made from ABS material, is suitable for industrial applications, and has an outstanding application effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the embodiments are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0023] Figure 1 The figure is a schematic diagram of the process for preparing modified polypropylene material. DETAILED DESCRIPTION

[0024] The following embodiments are described in detail, and examples thereof are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementations described in the following embodiments do not represent all implementations consistent with the present application. They are only examples of systems and methods consistent with some aspects of the present application as detailed in the claims.

[0025] The freezer lining is a part installed on the freezer body and cooperates with the door to form a closed space with the door. In the process of producing the lining, due to cost requirements, in some embodiments, the lining is made of ABS material. When the outer shell of the freezer is made of metal, the thermal expansion and contraction coefficient of the metal material is small, and the thermal expansion and contraction coefficient of the ABS material is large. Due to the large difference in the thermal expansion and contraction coefficients of the two, the freezer lining is prone to cracking during use, which deteriorates the sealing of the freezer and affects its use. PP material has the characteristics of being resistant to folding and not easy to break. When the lining is made of PP material, due to the large shrinkage rate of PP material and the special structure of the freezer lining, the freezer lining is prone to warping and deformation.

[0026] Some embodiments of the present application provide a modified polypropylene material, whose components, measured by mass percentage, include: 40-75% copolymer PP, 10-30% homopolymer PP, 3-20% toughening agent, 1-5% scratch resistant agent, 0.2-5% compatibilizer, 1-3% titanium dioxide, 0.2-2% lubricant, 0.2-1.5% light stabilizer, and 0.2-1.5% antioxidant.

[0027] Copolymer PP is a random copolymer polypropylene, which is obtained by copolymerizing propylene monomer and 1-4% ethylene monomer under heating, pressure and catalyst. The solvent is evaporated and removed by high-temperature gas stripping method to obtain molten polypropylene, which is then extruded and granulated to obtain a granular product. Copolymer PP has low strength, high rigidity, good heat resistance, good dimensional stability and good low-temperature toughness.

[0028] Homopolymer PP is homopolymer polypropylene, which is polymerized from a single propylene monomer. The molecular chain does not contain ethylene monomer. It uses high-boiling point straight-chain hydrocarbons as solvents and operates at a temperature higher than the melting point of polypropylene. The resulting polymer is completely dissolved in the solvent and distributed homogeneously. Homopolymer PP has high strength, poor impact resistance, poor low-temperature toughness, poor dimensional stability, easy aging, and poor long-term heat stability.

[0029] In order to obtain a freezer lining material with high strength and good low temperature toughness, in some embodiments, the melt mass flow rate MFR of the copolymer PP at 230°C and 2.16Kg load is greater than 10g / 10min, and the Izod notched impact strength of the copolymer PP is greater than 6Kj / m 2 In some embodiments, the melt mass flow rate MFR of homopolymer PP at 230°C and 2.16Kg load is greater than 2g / 10min. The Izod notched impact strength of homopolymer PP is greater than 3Kj / m 2 After blending the copolymer PP and homopolymer PP materials, the properties of the copolymer PP and homopolymer PP can be optimized to obtain a freezer lining material with higher strength and good low-temperature toughness.

[0030] During the use of the freezer lining, in order to provide a better use experience, its toughness and scratch resistance are necessary. In order to obtain a modified polypropylene material that is more suitable for the freezer lining, the various substances are mixed evenly according to the ratio shown in Table 1 to prepare the modified polypropylene materials of Examples 1-7 and Comparative Examples 1-2 for testing.

[0031] Table 1

[0032]

[0033] Table 2

[0034]

[0035] Referring to Table 1 and Table 2, in order to obtain better strength, low temperature toughness and scratch resistance, experiments were conducted using materials of different types and percentages.

[0036] In some embodiments, the toughening agent is a combination of any one or more of ethylene propylene diene monomer rubber EPDM and polyolefin elastomer POE, for example: Example 1 is a combination of ethylene propylene diene monomer rubber EPDM and polyolefin elastomer POE, wherein the polyolefin elastomer POE is 6% and the ethylene propylene diene monomer rubber EPDM is 2%; for another example: the toughening agent is selected from any one of ethylene propylene diene monomer rubber EPDM and polyolefin elastomer POE, wherein Examples 4 and 5 respectively select 14% of ethylene propylene diene monomer rubber EPDM and 9% of polyolefin elastomer POE.

[0037] Since the percentage of toughening agent is different in different embodiments, different effects will appear. When the ratio of toughening agent is Comparative Example 1 and Comparative Example 2, the percentage of toughening agent is 2.3%; when the ratio of toughening agent is Example 1, Example 2, Example 3 and Example 5, the percentage of toughening agent is 8-9%. At this time, the toughness of modified polypropylene material at low temperature is better than that of Comparative Example 1 and Comparative Example 2; when the ratio of toughening agent is Example 4, the percentage of toughening agent is 14%. At this time, the toughness of modified polypropylene material at low temperature is better than that of modified polypropylene material with a toughening agent percentage of 2.3%, but worse than that of modified polypropylene material with a toughening agent percentage of 8-9%; that is, when the percentage of toughening agent is 8-9%, the toughness of modified polypropylene material is better, and it has nothing to do with the selection of polyolefin elastomer POE or ethylene propylene diene monomer rubber EPDM. Therefore, in some embodiments, the percentage of toughening agent is 8-9%.

[0038] In use, in order to reduce the marks left after the lining is scratched, thereby affecting the use, in some embodiments, the scratch-resistant agent is a silicone masterbatch.

[0039] In order to better adjust and control the microscopic phase structure of copolymer PP and homopolymer PP, thereby achieving high performance and functional effects, in some embodiments, the modified polypropylene material also includes a compatibilizer, the percentage of the compatibilizer is 0.3%, and the compatibilizer can be any one or more combinations of silane coupling agents and titanate coupling agents.

[0040] Titanium dioxide can be used as a colorant and has reinforcing, anti-aging and filling effects. In some embodiments, the modified polypropylene material also includes titanium dioxide. For example, rutile titanium dioxide is selected. The lattice of rutile titanium dioxide is more stable, water-resistant and not easy to turn yellow.

[0041] Based on the above modified polypropylene material, some embodiments of the present application also provide a method for preparing the modified polypropylene material, see Figure 1 ,include:

[0042] It can be understood that, since the melt index of copolymer PP and homopolymer PP is small, the properties of copolymer PP and homopolymer PP such as breaking strength, hardness, toughness and aging resistance stability can be improved, so that the freezer lining prepared by this preparation method has better performance.

[0043] S100: adding copolymer PP, homopolymer PP, toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant into a high-speed mixer and mixing for 3-5 minutes to obtain a mixture;

[0044] Since the properties of copolymer PP and homopolymer PP are different, in order to optimize the properties of the two, first, the copolymer PP and the homopolymer PP are blended, and then the toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added to a high-speed mixer. Exemplarily, the mixing time of the mixer is 3 minutes, 4 minutes, and 5 minutes.

[0045] S200: adding the mixture into a twin-screw extruder, extruding and granulating, and obtaining a modified polypropylene material.

[0046] In some embodiments, the temperature range of the twin-screw extruder is 180-220° C., and the screw speed range of the twin-screw extruder is 300-500 rpm / min. Exemplarily, the temperature of the twin-screw extruder can be 180° C., 190° C., 200° C., 210° C., 220° C., and the screw speed of the twin-screw extruder is 300 rpm / min, 400 rpm / min, 500 rpm / min.

[0047] Without considering the effects of toughening agents, scratch resistant agents, compatibilizers, titanium dioxide, lubricants, light stabilizers and antioxidants on the modified polypropylene material, Examples 12, 13 and Comparative Example 3 were used to test the effects of the percentages of copolymer PP and homopolymer PP on the performance of the modified polypropylene material.

[0048] In Example 12, copolymer PP, homopolymer PP, toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added into a high-speed mixer for blending, wherein the percentage of copolymer PP is 70%, the percentage of homopolymer PP is 15%, and the percentage of other materials is 15%.

[0049] Example 13, copolymer PP, homo PP, toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added into a high-speed mixer for blending, wherein the percentage of copolymer PP is 65%, the percentage of homo PP is 20%, and the percentage of other materials is 15%.

[0050] In Comparative Example 3, copolymer PP, homopolymer PP, toughening agent, scratch resistance agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added into a high-speed mixer for blending, wherein the percentage of copolymer PP is 90%, the percentage of homopolymer PP is 5%, and the percentage of other materials is 5%.

[0051] It is understood that the mixing time, the temperature of the twin-screw extruder and the screw speed in Examples 12-13 and Example 3 are the same.

[0052] Table 3

[0053]

[0054] It can be seen from Table 3 that the performance difference between the modified polypropylene materials of Example 12 and Example 13 is relatively small, that is, when the percentage of copolymer PP and homopolymer PP is 85%, the difference in the impact on the performance is relatively small. When the percentage of copolymer PP and homopolymer PP is 95%, except that the cantilever beam notched impact strength is slightly different from that of Example 12 and Example 13, the other performance indexes are quite different. Therefore, in some embodiments, the percentage of copolymer PP and homopolymer PP is 85%.

[0055] In addition to the influence of the percentage of copolymer PP and homopolymer PP on the modified polypropylene material, the mixing time also has an influence on the modified polypropylene material. Example 14 and Comparative Example 4 were used for testing.

[0056] Example 14, copolymer PP, homo PP, toughening agent, scratch resistant agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added to a high-speed mixer for blending, wherein the percentage of copolymer PP is 70%, the percentage of homo PP is 15%, and the percentage of other materials is 15%; the mixing time is 3 minutes, the mixture is added to a twin-screw extruder, extruded and granulated to obtain a modified polypropylene material, wherein the temperature of the twin-screw extruder is 200°C and the screw speed is 400rpm / min.

[0057] In Comparative Example 4, copolymer PP, homopolymer PP, toughening agent, scratch resistant agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant are added to a high-speed mixer for blending, wherein the percentage of copolymer PP is 70%, the percentage of homopolymer PP is 15%, and the percentage of other materials is 15%; the mixing time is 6 minutes, and the mixture is added to a twin-screw extruder, extruded and granulated to obtain a modified polypropylene material, wherein the temperature of the twin-screw extruder is 200°C and the screw speed is 400rpm / min.

[0058] Table 4

[0059] Test items Test Method Test conditions unit Embodiment 14 Comparative Example 4 Tensile Strength GB / T1040 50mm / min MPa 26 25 Elongation at break GB / T1040 50mm / min ％ 55 53 Bending Strength GB / T9341 2mm / min MPa 32 30 Flexural modulus GB / T9341 2mm / min MPa 1450 1400 Izod notched impact strength GB / T1843 4mm,23℃ Kj / m2 12 10 Rockwell hardness GB / T3398 R scale / 95 93

[0060] Referring to Example 14 and Comparative Example 4, since the blending time of Example 14 is different from that of Comparative Example 4, when the blending time is 6 min, it can be seen from Table 4 that the various performance indexes of Comparative Example 4 are smaller than those of Example 14, that is, the blending time will affect the various properties of the modified polypropylene material.

[0061] Based on the above-mentioned modified polypropylene material and preparation method thereof, some embodiments of the present application also provide application of the modified polypropylene material in the lining of a freezer.

[0062] The present application provides a modified polypropylene material and its preparation method and application, the material includes: copolymer PP is 40-75%, homopolymer PP is 10-30%, toughening agent is 3-20%, scratch resistance agent is 1-5%, compatibilizer is 0.2-5%, titanium dioxide is 1-3%, lubricant is 0.2-2%, light stabilizer is 0.2-1.5%, antioxidant is 0.2-1.5%. The freezer lining prepared by the material solves the problem that the freezer lining is prone to warping and deformation. It can obtain better assembly performance with the metal shell, and the freezer lining prepared by the material has a qualified appearance after high and low temperature tests, without cracking and other phenomena. The preparation method of the modified polypropylene material provided by the present application can optimize the performance of copolymer PP and homopolymer PP to obtain better low-temperature impact resistance and rigidity. The freezer lining prepared by the material is lower in cost than the freezer lining prepared by ABS material, is suitable for industrial applications, and has outstanding application effects.

[0063] Similar parts between the embodiments provided in this application can be referenced to each other. The specific implementation methods provided above are only a few examples under the general concept of this application and do not constitute a limitation on the protection scope of this application. For those skilled in the art, any other implementation methods expanded based on the scheme of this application without creative work belong to the protection scope of this application.

Claims

1. A modified polypropylene material, characterized in that: The composition thereof comprises, by mass percentage, 40-75% copolymer PP, 10-30% homopolymer PP, 8-9% toughening agent, 1-5% scratch resistant agent, 0.3% compatibilizer, 1-3% titanium dioxide, 0.2-2% lubricant, 0.2-1.5% light stabilizer, and 0.2-1.5% antioxidant. The toughening agent is any one or more combination of EPDM and POE, and the compatibilizer is any one or more combination of silane coupling agent and titanate coupling agent. The melt mass flow rate of the copolymer PP at 230°C and 2.16Kg load is greater than 10g / 10min, and the notched cantilever beam impact strength of the copolymer PP is greater than 6Kj / m 2 The melt mass flow rate of the homopolymer PP at 230°C and 2.16Kg load is greater than 2g / 10min, and the Izod notched impact strength of the homopolymer PP is greater than 3Kj / m 2 .

2. The modified polypropylene material according to claim 1, characterized in that: The anti-scratch agent is silicone masterbatch.

3. The method for preparing the modified polypropylene material according to any one of claims 1 to 2, characterized in that: include: Add copolymer PP, homopolymer PP, toughening agent, scratch resistant agent, compatibilizer, titanium dioxide, lubricant, light stabilizer and antioxidant into a high-speed mixer and mix for 3-5 minutes to obtain a mixture, wherein the copolymer PP is 40-75%, the homopolymer PP is 10-30%, the toughening agent is 8-9%, the scratch resistant agent is 1-5%, the compatibilizer is 0.2-5%, the titanium dioxide is 1-3%, the lubricant is 0.2-2%, the light stabilizer is 0.2-1.5%, and the antioxidant is 0.2-1.5%. The toughening agent is any one or more combinations of ethylene propylene diene monomer rubber EPDM and polyolefin elastomer POE, the compatibilizer is any one or more combinations of silane coupling agent and titanate coupling agent, the melt mass flow rate of the copolymer PP at 230°C and 2.16Kg load is greater than 10g / 10min, and the notched cantilever beam impact strength of the copolymer PP is greater than 6Kj / m 2 The melt mass flow rate of the homopolymer PP at 230°C and 2.16Kg load is greater than 2g / 10min, and the Izod notched impact strength of the homopolymer PP is greater than 3Kj / m 2 ; The mixture is added into a twin-screw extruder and extruded into pellets to obtain a modified polypropylene material.

4. The preparation method according to claim 3, characterized in that: The temperature range of the twin-screw extruder is 180-220° C., and the screw speed range of the twin-screw extruder is 300-500 rpm / min.

5. Use of the modified polypropylene material according to any one of claims 1 to 2 in the lining of a freezer.

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