High-performance modified polypropylene for thin-wall products as well as preparation method and application of high-performance modified polypropylene

Abstract

The invention discloses high-performance modified polypropylene for thin-wall products, which comprises a homo-polypropylene matrix and a non-uniformly distributed surface-treated co-polypropylene dispersed phase, and the surface of the surface-treated co-polypropylene is partially or completely wrapped with chlorinated polypropylene. The invention also discloses a preparation method of the high-performance modified polypropylene, application of the high-performance modified polypropylene as a thin-wall product, and a method for preparing the thin-wall product from the high-performance modified polypropylene. The modified polypropylene provided by the invention contains two main phase components, one main phase component is that a homo-polypropylene matrix can provide high rigidity, and the other main phase component is that the homo-polypropylene matrix can be stretched into a microfiber-shaped co-polypropylene dispersed phase by a mold flow in the processing process, so that the situation that the compatibility of the homo-polypropylene matrix and the co-polypropylene dispersed phase is too high, co-melting and co-crystallizing are generated, and the generation of microfibers is influenced is prevented; a chlorinated polypropylene micro-interface is attached to the surface layer of the co-polypropylene; finally, the modified polypropylene provided by the invention realizes balance and collective improvement of melt flowability, rigidity and impact resistance of the modified polypropylene.

Description

Technical Field

[0001] The present invention relates to the technical field of modified polypropylene materials, and in particular to a high-performance modified polypropylene for thin-wall products and a preparation method and application thereof. Background Art

[0002] Polypropylene (PP) has low density, excellent mechanical properties, good stress crack resistance, fatigue yield resistance and chemical resistance, and has the advantages of low cost, easy processing, non-toxicity, easy recovery and recyclability, and has been widely used. However, as a cheap general-purpose plastic, the performance of PP is still limited by its performance in some special applications. For example, thin-walled products require materials to meet good rigidity, excellent toughness, and high fluidity at the same time. These three are difficult for PP to meet at the same time, and alloying modification is required.

[0003] CN109401045B discloses a high-performance functional alloy-modified polypropylene corrugated pipe special material and a preparation method thereof. A special material for producing corrugated pipes is prepared by using homopolymer polypropylene powder, block copolymer polypropylene powder, filler, volume increaser and toughening agent, fluidity modifier, flame retardant, antioxidant, ultraviolet absorber, etc., and relatively good mechanical properties, low-temperature impact resistance, high heat deformation temperature, etc. are obtained, but the material is only suitable for use in corrugated pipes.

[0004] CN111269490A discloses a high-rigidity flame-retardant polypropylene alloy material and a preparation method thereof. A polypropylene alloy having the advantages of high strength, high modulus, environmental protection, flame retardancy, low water absorption, etc. is prepared by combining polypropylene, polyamide, glass fiber, halogen-free flame retardant, compatibilizer, micro-crosslinking agent, modified inorganic nanofiller, coupling agent, flow modifier and other additives. The polypropylene alloy contains a large amount of polyamide and inorganic components and is not suitable for thin-walled products.

[0005] CN111117073A discloses a blended ultra-high molecular weight polypropylene / polypropylene alloy and a preparation method thereof. Based on the principle of like-is-compatible, ultra-high molecular weight polypropylene and polypropylene have similar molecular segments and ordinary polypropylene has excellent processing properties. A small amount of ultra-high molecular weight polypropylene and polypropylene are melt-blended and extruded to prepare an ultra-high molecular weight polypropylene / polypropylene alloy. This alloy has good properties, but has high melt strength and low fluidity.

[0006] None of the above-mentioned related technologies have achieved the balance of rigidity, toughness and fluidity when the main material is polypropylene, and all of them have a homogeneous structure. There is also a lack of technology in the market that uses in-situ shearing to generate an inhomogeneous microfiber phase inside the material. Summary of the invention

[0007] Based on the above, the purpose of the present invention is to provide a high-performance modified polypropylene for thin-wall products and its preparation method and application. The high-performance modified polypropylene provided by the present invention includes a non-uniformly distributed homopolymerized polypropylene matrix and a surface-treated copolymerized polypropylene dispersed phase. Unlike the general method of promoting the compatibility modification of components in traditional polymers, the present invention takes the opposite approach, and the homopolymerized polypropylene matrix and the surface-treated copolymerized polypropylene dispersed phase are non-uniformly distributed.

[0008] To this end, in a first aspect, the present invention provides a high-performance modified polypropylene for thin-walled products, comprising a homopolymer polypropylene matrix and a non-uniformly distributed surface-treated copolymer polypropylene dispersed phase, wherein the surface of the surface-treated copolymer polypropylene is partially or completely coated with chlorinated polypropylene.

[0009] Specifically, the surface-treated copolymer polypropylene has an obvious interface structure that is closely integrated with the matrix. Under the action of these interfaces, surface-treated copolymer polypropylene oriented microfibers can be formed inside the final product during shearing, thereby improving the overall performance of the material.

[0010] As a specific embodiment of the present invention, preferably, the modified polypropylene comprises 71.2-88.6 parts of homopolypropylene and 6-18 parts of surface-treated copolymer polypropylene by weight.

[0011] As a specific embodiment of the present invention, preferably, the surface treatment method of the surface-treated copolymer polypropylene comprises: soaking the copolymer polypropylene powder in a chlorinated polypropylene xylene solution, and vacuum drying to remove the xylene; further preferably, the amounts of the xylene, the chlorinated polypropylene and the copolymer polypropylene powder are 5-10 parts, 1-3 parts and 5-15 parts by mass, respectively.

[0012] As a specific embodiment of the present invention, preferably, the temperature at which xylene dissolves chlorinated polypropylene is 20-50°C, and more preferably 25-35°C.

[0013] As a specific embodiment of the present invention, preferably, the comonomer of the copolymerized polypropylene powder is ethylene, and more preferably, the content of ethylene monomer is 8-15%; and / or the copolymerized polypropylene powder has a melt index of 20-55 g / 10 min at 230°C and 2.16 kg according to GB / T3682.1-2018 standard.

[0014] As a specific embodiment of the present invention, preferably, the particle size of the copolymerized polypropylene powder is 80-1000 mesh, more preferably 80-200 mesh, and further preferably the copolymerized polypropylene for fiber or biaxially stretched film; and / or the chlorine content of the chlorinated polypropylene is 26%-36%.

[0015] As a specific embodiment of the present invention, preferably, the isotacticity of the homopolypropylene is not less than 95%. Further preferably, according to GB / T 3682.1-2018 standard, the melt index is 30-60 g / 10 min at 230° C. and 2.16 kg.

[0016] As a specific embodiment of the present invention, preferably, it also includes a nucleating agent and an antioxidant. More preferably, the amount of the nucleating agent is 0.3-0.5 parts by mass, and the amount of the antioxidant is 0.1-0.3 parts by mass; further preferably, the nucleating agent is Milliken 20E, and / or the antioxidant is BASF's 225.

[0017] To this end, in a second aspect, the present invention also provides a method for preparing the above-mentioned modified polypropylene, comprising the following steps: fully mixing the surface-treated copolymer polypropylene powder with the homopolymer polypropylene powder to obtain the modified polypropylene; preferably, the particle size of the homopolymer polypropylene powder is 80-1000 mesh, more preferably 80-200 mesh; further preferably, the mixing conditions are: rotation speed 100-300rpm, temperature 25-35°C, time 10-30min.

[0018] As a specific embodiment of the present invention, preferably, a nucleating agent and an antioxidant are also added.

[0019] To this end, in a third aspect, the present invention also provides a use of the modified polypropylene as a thin-walled product.

[0020] To this end, in a fourth aspect, the present invention also provides a method for preparing thin-walled products from modified polypropylene, comprising the following steps: subjecting the modified polypropylene to injection molding or extrusion granulation and then injection molding to obtain a thin-walled product; preferably, the temperature of the injection molding nozzle is 200-220°C, and the melt flow rate at the nozzle during injection is 100-200mm / s; further preferably, the temperature of the extrusion granulation is 190-220°C, and the rotation speed is 40-80rpm.

[0021] Specifically, since the fully mixed surface-treated copolymer polypropylene powder and homopolymer polypropylene powder have good fluidity, a relatively high injection speed should be used during the injection molding process to ensure that the injection molding material flow rate reaches 100-200 mm / s, so that the surface-treated copolymer polypropylene dispersed phase can be oriented and microfibrillated under the action of high-speed mold flow, thereby improving the rigidity and impact resistance of the final product.

[0022] The present invention has the following advantages and beneficial effects:

[0023] (1) The modified polypropylene provided by the present invention contains two main phase components, one of which is a homopolymer polypropylene matrix that can provide high rigidity, and the other is a surface-treated copolymer polypropylene dispersed phase that can be stretched into microfibers by mold flow during processing. In order to prevent the two from being too compatible to produce eutectic and affect the generation of microfibers, a layer of chlorinated polypropylene micro-interface is attached to the surface of the surface-treated copolymer polypropylene;

[0024] (2) The modified polypropylene provided by the present invention achieves a balance and collective improvement in the melt fluidity, rigidity and impact resistance of the modified polypropylene.

[0025] (3) Although the modified polypropylene material technology provided by the present invention adopts a two-step production method, the production technology is simple, the amount of toughness component used is small, and it can be achieved by using traditional plastic modification processing methods. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0027] In the following examples and comparative examples, the homopolymer polypropylene has a melt index of 50 g / 10 min at 230° C. and a load of 2.16 kg, an isotacticity of 97%, and a particle size of 80 mesh; the copolymer polypropylene has a melt index of 30 g / 10 min at 230° C. and a load of 2.16 kg, wherein the ethylene monomer content is 12%, and the particle size is 80 mesh; the chlorinated polypropylene is Nippon Paper 830L, wherein the chlorine content is 26%; the nucleating agent is Milliken 20E; and the antioxidant is BASF's 225.

[0028] Example 1

[0029] The modified polypropylene for thin-walled products provided in this embodiment has the following formula:

[0030] Homopolymer polypropylene 88.6 parts,

[0031] 5 parts of copolymerized polypropylene,

[0032] 0.3 parts of nucleating agent,

[0033] 1 part of chlorinated polypropylene,

[0034] Antioxidant 0.1 part,

[0035] 5 parts of xylene (used in the pretreatment process, but after the pretreatment, the xylene is removed by vacuum drying).

[0036] The preparation method of the modified polypropylene is as follows:

[0037] The preparation method is prepared by a two-step method. First, a xylene solution in which chlorinated polypropylene is dissolved is used to soak copolymer polypropylene powder for 5 minutes at room temperature. After the soaking is completed, the xylene solution of excess chlorinated polypropylene is drained off, and then the xylene component in the soaked copolymer polypropylene is removed by vacuum drying at 70°C for 24 hours to obtain a surface-treated copolymer polypropylene powder. Then, the surface-treated copolymer polypropylene powder is fully mixed with a homopolymer polypropylene powder and a nucleating agent in a high-speed mixer at a speed of 150 rpm at room temperature for 15 minutes to obtain modified polypropylene for thin-walled products.

[0038] The prepared thin-walled products were directly injection molded into thin-walled products using modified polypropylene in an injection molding machine. The temperature of the injection molding nozzle was set to 210° C. The melt flow rate at the nozzle during injection was 100 mm / s. The products were cut into standard specimens and tested.

[0039] Example 2

[0040] The modified super polypropylene for thin-walled products provided in this embodiment has the following formula:

[0041] Homopolymer polypropylene 71.2 parts

[0042] Copolymer polypropylene 15 parts

[0043] Nucleating agent 0.5 parts

[0044] 3 parts of chlorinated polypropylene

[0045] 0.3 parts of antioxidant

[0046] 10 parts of xylene (used in the pretreatment process, but after the pretreatment, the xylene is removed by vacuum drying).

[0047] The preparation method of the modified polypropylene is as follows:

[0048] The preparation method is prepared by a two-step method. First, a xylene solution in which chlorinated polypropylene is dissolved is used to soak copolymer polypropylene powder for 5 minutes at room temperature. After the soaking is completed, the xylene solution of excess chlorinated polypropylene is drained off, and then the xylene component in the soaked copolymer polypropylene is removed by vacuum drying at 70°C for 24 hours to obtain a surface-treated copolymer polypropylene powder. Then, the surface-treated copolymer polypropylene powder is fully mixed with a homopolymer polypropylene powder and a nucleating agent in a high-speed mixer at a speed of 150 rpm at room temperature for 15 minutes to obtain modified polypropylene for thin-walled products.

[0049] The modified polypropylene for the prepared thin-walled products was first extruded into granules by a single screw at 205°C and 50rpm, and then injection molded into thin-walled products in an injection molding machine. The injection nozzle temperature was set to 210°C, and the melt flow rate at the nozzle during injection was 200mm / s. The products were cut into standard strips for testing.

[0050] Example 3

[0051] The modified super polypropylene for thin-walled products provided in this embodiment has the following formula:

[0052] Homopolymer polypropylene 77.2 parts

[0053] Copolymer polypropylene 10 parts

[0054] Nucleating agent 0.5 parts

[0055] 2 parts of chlorinated polypropylene

[0056] 0.3 parts of antioxidant

[0057] 10 parts of xylene (used in the pretreatment process, but after the pretreatment, the xylene is removed by vacuum drying).

[0058] The preparation method of the modified polypropylene is as follows:

[0059] The preparation method is prepared by a two-step method. First, a xylene solution in which chlorinated polypropylene is dissolved is used to soak copolymer polypropylene powder for 5 minutes at room temperature. After the soaking is completed, the xylene solution of excess chlorinated polypropylene is drained off, and then the surface-treated copolymer polypropylene powder is prepared by vacuum drying at 70°C for 24 hours to remove the xylene component therein; then the surface-treated copolymer polypropylene powder is fully mixed with homopolymer polypropylene powder and a nucleating agent in a high-speed mixer at a speed of 150 rpm at room temperature for 15 minutes to prepare a modified super polypropylene for thin-walled products.

[0060] The modified super polypropylene for the prepared thin-walled products was first extruded into granules by a single screw at 205°C and 50rpm, and then injected at high speed in an injection molding machine to form thin-walled products. The injection nozzle temperature was set to 210°C, and the melt flow rate at the nozzle during injection was 200mm / s. The products were cut into standard strips and tested.

[0061] Comparative Example 1

[0062] The modified polypropylene formula is as follows:

[0063] Homopolymer polypropylene 88.6 parts,

[0064] 5 parts of copolymerized polypropylene,

[0065] 0.3 parts of nucleating agent,

[0066] 1 part of chlorinated polypropylene,

[0067] Antioxidant 0.1 part,

[0068] The preparation method of modified polypropylene is as follows:

[0069] The above raw materials were directly added into a twin-screw extruder, and the modified polypropylene material was extruded at a processing temperature of 220° C. and a rotation speed of 200 rpm. In this comparative example, all components were almost evenly dispersed.

[0070] Comparative Example 2

[0071] The modified polypropylene formula is as follows:

[0072] Homopolymer polypropylene 71.2 parts,

[0073] 15 parts of copolymerized polypropylene,

[0074] 0.5 parts of nucleating agent,

[0075] 3 parts of chlorinated polypropylene,

[0076] 0.3 parts of antioxidant,

[0077] The preparation method is as follows:

[0078] The above raw materials were directly added into a twin-screw extruder, and the modified polypropylene material was extruded at a processing temperature of 220° C. and a rotation speed of 200 rpm. In this comparative example, all components were almost evenly dispersed.

[0079] The modified polypropylene materials prepared in the above examples and comparative examples and the commercially available modified polypropylene materials were tested respectively, and the test results are listed in Table 1.

[0080] The test standards and conditions are as follows:

[0081] Bending performance test: According to GB / T 9341-2008 standard, the prepared specimens were subjected to a bending test.

[0082] Impact strength test: The impact performance test was carried out on the prepared standard impact specimens according to GB / T 1843-2008.

[0083] Melt index test: The melt flow rate of the prepared material is tested at 230°C and 2.16 kg load according to GB / T 3682.1-2018.

[0084] Table 1 Test data of modified polypropylene materials for thin-walled products and performance comparison of comparative examples and commercially available polypropylene

[0085]

[0086] Note: The comparative examples and commercial brands mentioned above use standard plastic strips, while the examples use thin-walled strips.

[0087] In summary, the modified polypropylene provided by the present invention contains two main phase components, one is a homopolymer polypropylene matrix that can provide high rigidity, and the other is a surface-treated copolymer polypropylene dispersed phase that can be stretched into microfibers by mold flow during processing. In order to prevent the two from being too compatible to produce eutectic and affect the generation of microfibers, a layer of chlorinated polypropylene micro-interface is attached to the surface of the surface-treated copolymer polypropylene; finally, the modified polypropylene provided by the present invention achieves a balance and collective improvement in the melt fluidity, rigidity and impact resistance of the modified polypropylene.

[0088] In addition, although the modified polypropylene material technology provided by the present invention is produced by a two-step method, the production technology is simple, the amount of toughness component used is small, and it can be achieved by using traditional plastic modification processing methods.

[0089] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0090] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A high-performance modified polypropylene for thin-wall products, characterized in that: The invention comprises a homopolymer polypropylene matrix and a non-uniformly distributed surface-treated copolymer polypropylene dispersed phase, wherein the surface of the surface-treated copolymer polypropylene is partially or completely coated with chlorinated polypropylene.

2. The modified polypropylene according to claim 1, characterized in that The modified polypropylene comprises, by weight, 71.2-88.6 parts of homopolymer polypropylene and 6-18 parts of surface-treated copolymer polypropylene.

3. The modified polypropylene according to claim 1 or 2, characterized in that: The surface treatment method of the surface-treated copolymer polypropylene comprises: soaking copolymer polypropylene powder in a chlorinated polypropylene xylene solution, and vacuum drying to remove xylene; preferably, the amounts of the xylene, the chlorinated polypropylene and the copolymer polypropylene powder are 5-10 parts, 1-3 parts and 5-15 parts by mass, respectively.

4. The modified polypropylene according to claim 3, characterized in that The comonomer of the copolymerized polypropylene powder is ethylene, and preferably the content of ethylene monomer is 8-15%; and / or the copolymerized polypropylene powder has a melt index of 20-55 g / 10 min at 230° C. and 2.16 kg according to GB / T 3682.1-2018 standard.

5. The modified polypropylene according to claim 3 or 4, characterized in that: The particle size of the copolymerized polypropylene powder is 80-1000 mesh, preferably 80-200 mesh, more preferably copolymerized polypropylene for fiber or biaxially stretched film; and / or the chlorine content of the chlorinated polypropylene is 26%-36%.

6. The modified polypropylene according to any one of claims 1 to 5, characterized in that: The isotacticity of the homopolypropylene is not less than 95%. Preferably, according to GB / T 3682.1-2018 standard, the melt index is 30-60 g / 10 min at 230° C. and 2.16 kg.

7. The modified polypropylene according to any one of claims 1 to 6, characterized in that: It also includes a nucleating agent and an antioxidant. Preferably, the amount of the nucleating agent is 0.3-0.5 parts by weight, and the amount of the antioxidant is 0.1-0.3 parts by weight; more preferably, the nucleating agent is Milliken 20E, and / or the antioxidant is BASF's 225.

8. A method for preparing high-performance modified polypropylene for thin-wall products according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: fully mixing the surface treated copolymer polypropylene powder with homopolymer polypropylene powder to obtain modified polypropylene; preferably, the particle size of the homopolymer polypropylene powder is 80-1000 mesh, more preferably 80-200 mesh; preferably, the mixing conditions are: rotation speed 100-300rpm, temperature 25-35°C, time 10-30min.

9. The preparation method according to claim 8, characterized in that: Nucleating agents and antioxidants are also added.

10. Use of the modified polypropylene according to any one of claims 1 to 7 as a thin-walled product.

11. A method for preparing thin-walled products by modified polypropylene, characterized in that: The method comprises the following steps: subjecting the modified polypropylene according to any one of claims 1 to 7 to injection molding or extrusion granulation and then injection molding to obtain a thin-walled product; preferably, the temperature of the injection molding nozzle is 200-220° C., and the melt flow rate at the nozzle during injection is 100-200 mm / s; preferably, the temperature of the extrusion granulation is 190-220° C., and the rotation speed is 40-80 rpm.

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