Nano-compatible polypropylene / polystyrene composition and method for producing the same

Abstract

The present invention relates to a nano-compatible polypropylene-polystyrene composition and a method for preparing the same. The weight components of the composition are 60-80 parts of polypropylene resin, 20-40 parts of modified polystyrene nanofiber nonwoven fabric, 0.1-1 part of antioxidant, and 0.1-1 part of lubricant. The polypropylene resin, antioxidant, and lubricant are added to a mixer and mixed well, and then fed into the main feed of a screw machine, and the modified polystyrene nanofiber nonwoven fabric is added to the side feed port of the 8th zone by weight loss control at the same time. The melt extrusion is carried out at an extrusion temperature of 180-210°C and a screw speed of 200-500 rpm, and then cooled and granulated to obtain a nano-compatible polypropylene-polystyrene composition. Compared with the existing technology, the present invention can effectively improve the compatibility of polystyrene and polypropylene, and the obtained polystyrene / polypropylene resin composition has excellent toughness, chemical resistance, high strength, is easy to manufacture, has low material cost, and can make up for the performance deficiencies of polystyrene and polypropylene.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to a nano-compatible polypropylene-polystyrene composition and a method for producing the same.

Background Art

[0002] Polypropylene materials are widely used in the fields of plastics and films because of their simple raw materials and low cost. However, due to the low steric hindrance of the molecular chain of polypropylene materials, although they have good toughness, their mechanical strength is low and their rigidity is poor. Furthermore, since this material is prone to crystallization and has a large shrinkage rate, its dimensional stability during the injection molding process is poor and it is prone to deformation, so its scope of use is greatly limited. Polystyrene (PS) is a polymer material obtained by free radical polymerization of styrene, and has high rigidity, high transparency, and low impact properties due to the steric hindrance of the benzene ring in the side chain. Similarly, since its raw materials are also easily available and the cost is low, it is widely used in the field of plastics. Therefore, in order to combine the advantages of these two materials to obtain a comprehensively excellent material with high toughness, high rigidity, and low shrinkage, it is very necessary to make these two materials into an alloy material. However, since the solubility parameters of polyolefin and polystyrene are very different, their compatibility becomes poor.

[0003] Traditional compatibilization methods involve adding a compatibilizer to both materials. For example, Chinese invention patent application, publication number CN108276657A, discloses the use of PP-g-maleic anhydride as a phase solvent, directly blending it with polypropylene and polystyrene, and then melt-extruding the mixture. However, this direct blending method often requires the addition of large amounts of compatibilizer, significantly increasing manufacturing costs. At the same time, the compatibilizer cannot be reliably positioned between the polypropylene and polystyrene phases, and therefore a good compatibility effect cannot be obtained. Chinese invention patent application, publication number CN102643484B, discloses in-situ compatibilized polyolefin / polystyrene alloys, their manufacturing method, and applications. This technology achieves the objective of compatibilizing polyolefins and polystyrene by directly adding a compatibilization initiation mother liquor, consisting of a crosslinking agent, a co-crosslinking agent, and an oily carrier, to the polyolefins and polystyrene. However, when the mother liquor is added directly to the mixture, it is not easy to uniformly disperse the mother liquor within the substrate, and aggregation is likely to occur. As a result, excessive crosslinking occurs locally, which can affect the physical properties. This can reduce the compatibility efficiency and make process control difficult.

[0004] Currently, there is no efficient, low-cost, and controllable method for compatibilizing polypropylene and polystyrene to prepare high-performance polypropylene-polystyrene compositions. [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a nano-compatible polypropylene-polystyrene composition and a method for producing the same for improving the compatibility between polystyrene and polypropylene. [Means for solving the problem]

[0006] The object of the present invention can be achieved by the following technical solution: the nano-compatible polypropylene-polystyrene composition contains, by weight, the following components: 60-80 parts polypropylene resin, 20-40 parts modified polystyrene nanofiber nonwoven fabric, 0.1-1 part antioxidant, and 0.1-1 part lubricant.

[0007] The modified polystyrene nanofiber nonwoven fabric is preferably a nanofiber nonwoven fabric with a fiber diameter in the range of 100 to 600 nm, obtained by electrospinning a polystyrene resin and a PP-g-MAH composition.

[0008] More preferably, a polystyrene resin and a PP-g-MAH composition are mixed in a DMF solution, and a nanofiber nonwoven fabric is obtained by electrospinning.

[0009] More preferably, the polystyrene resin and PP-g-MAH composition comprises, by weight, the following components: 98-99 parts polystyrene resin and 1-2 parts PP-g-MAH.

[0010] More preferably, a method for producing a modified polystyrene nanofiber nonwoven fabric includes the following steps. (1) Dissolve polystyrene resin and PP-g-MAH in DMF to prepare a solution with a polymer concentration of 15-25% by weight. (2) The solution obtained in step (1) is electrospinned to produce a modified polystyrene nanofiber nonwoven fabric. The electrospinning voltage is controlled to 25-35kV, the forward speed to 4-6μl / min, and the ambient temperature and humidity to 20-25°C and 25-35%. (3) The modified polystyrene nanofiber nonwoven fabric obtained in (2) is crushed to obtain small pieces of nonwoven fabric.

[0011] Preferably, in step (1), a solution with a polymer concentration of 20% by weight is prepared.

[0012] Preferably, in step (2), the electrospinning voltage is controlled to 30kV, the forward speed is controlled to 5μl / min, and the ambient temperature and humidity are controlled to 23°C and 30%.

[0013] More preferably, the melt index flow rate MI (200°C × 5kg) of the polystyrene resin is 3 to 8 g / 10 min.

[0014] The polypropylene resin preferably contains either or both copolymerized polypropylene resin and homopolymerized polypropylene resin.

[0015] Preferably, the antioxidant is a mixture of one or more of 2,6-di-tert-butyl-4-methylphenol, dilauryl thiodipropionate, thiodipropionate distearate, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butyl)quaternary tetrahydrol diphosphite, or pentaerythritol bisphosphite di(octadecanol) ester.

[0016] Preferably, the lubricant is one or a mixture of ethylene bis-stearamide, stearate, and silicone lubricants.

[0017] A method for preparing the above-mentioned nano-compatible polypropylene / polystyrene composition, comprising the following steps: adding polypropylene resin, antioxidant and lubricant to a high-speed mixer and mixing thoroughly, then feeding it into the main feed of a screw machine; after a period of time, adding modified polystyrene nanofiber nonwoven fabric to the side feed port of the 8th zone by weight reduction control, and performing melt extrusion at an extrusion temperature of 180-210°C and a screw rotation speed of 200-500 rpm; and then cooling to obtain the nano-compatible polypropylene / polystyrene composition. Preferably, during the preparation process, the temperature of the seventh zone is set to 100°C. [Effects of the Invention]

[0018] Compared to conventional technology, the present invention has the following advantages. 1. The present invention can effectively improve the compatibility of polystyrene and polypropylene, thereby improving the overall mechanical properties of polystyrene / polypropylene alloys.

[0019] 2. In this invention, polystyrene and PP-g-MAH are mixed and electrospinned to form nanofibers, which are then added to a polypropylene molten material by side feeding. This allows polystyrene to be directly integrated into polypropylene in a nanophase state. As a result, the phase state of polystyrene is reduced, and the compatibility between the two is greatly improved.

[0020] 3. In this invention, the PP-g-MAH compatibilizer is first mixed with polystyrene, and then melt-mixed with polypropylene. When polystyrene nanofibers are blended with polypropylene in this way, PP-g-MAH has better compatibility with polypropylene, so it easily comes out of the polystyrene phase and enters between them, improving the efficiency of the compatibilizer and increasing the compatibility between the two.

[0021] 4. The present invention involves cooling the polypropylene molten material before adding polystyrene nanofibers and lowering the temperature to 100°C before side feeding to prevent premature melting of polystyrene nanofibers and ensure a smooth blending effect.

[0022] 5. The polystyrene / polypropylene resin composition obtained by the present invention has excellent toughness, chemical resistance, and high strength, is easy to manufacture, has low material costs, and high production efficiency, and can compensate for the performance shortcomings of polystyrene and polypropylene. [Modes for carrying out the invention]

[0023] Embodiments of the present invention will be described in detail below, but the following examples are based on the technical solutions of the present invention and provide detailed embodiments and specific operating processes, without limiting the scope of protection of the present invention.

[0024] (Implementation Example) A method for preparing a nanocompatible polypropylene and polystyrene composition, the method comprising the following steps. (1) According to the weight percentages of the compounding components in Table 1, dissolve in DMF to prepare a solution with a polymer concentration of 20 wt%.

[0025]

Table 1

[0026] (2) Electrospin the solution obtained in step (1) to produce a modified polystyrene nanofiber non-woven fabric. The electrospinning voltage is controlled at 30 kV, the forward speed is controlled at 5 μl / min, and the ambient temperature and humidity are controlled at 23 °C and 30% respectively.

[0027] (3) Grind the modified polystyrene nanofiber non-woven fabric obtained in (2) to obtain small pieces of the non-woven fabric.

[0028] (4) Add the compounding components in Table 2 in parts by weight to a high-speed mixer, mix them completely, and then put them into the main feed of a screw machine. At the same time, add the modified polystyrene nanofiber non-woven fabric in the parts by weight described in Table 2 to the side feed port of the eighth zone by weight control. Perform melt extrusion at an extrusion temperature of 180 - 210 °C (the temperature of the seventh zone is set at 100 °C) and a screw rotation speed of 400 rpm, and cool and pelletize to obtain a product.

[0029]

Table 2

[0030] Among these, the materials in Table 2 are as follows. Polypropylene 1: PP1120, homopolymer PP, Formosa Plastics. Polypropylene 2: PP4204, impact-resistant copolymer PP, Formosa Plastics. Antioxidant: 1:1 mixture of IG-1076 and IG-168, BASF. Lubricants: EBS, Sunkoo.

[0031] (Performance evaluation methods and implementation standards) Charpy-notch impact strength: The impact energy is measured at 4 J and 23°C according to the ISO 179-1:2010(E) standard. Tensile strength: Measured according to ISO 527:2010(E) standard. Measurement conditions are 5 kg, 50°C / h. Shrinkage rate: Measured according to GB / T 15585 standard. Compatibility: Observe the delamination of the gate area after injection molding.

[0032] (Comparative Examples 1-4) Comparative Examples 3 and 4 involved adding the raw materials to a high-speed mixer according to the parts by weight of the components listed in Table 3, mixing thoroughly, then placing the mixture into a screw machine, performing melt extrusion at an extrusion temperature of 180-210°C and a screw rotation speed of 400 rpm, and finally cooling and granulating to obtain the product.

[0033] The manufacturing method for Comparative Example 1 is the same as that for Example 1, except that the temperature of Zone 7 is set to 210°C.

[0034] The manufacturing method for Comparative Example 2 is the same as that for Example 1, except that PP-g-MAH is not added to the polystyrene nanofiber nonwoven fabric 3 during the manufacturing process.

[0035] [Table 3]

[0036] Comparative Example 3, compared to Example 1, does not use a nanofiber compatibilization method, resulting in poor compatibility between polypropylene and polystyrene, no improvement in physical properties, and even worse performance than the original polypropylene 1.

[0037] In Comparative Example 1, the temperature in Zone 7 did not decrease compared to Example 1, and the physical properties of the composition were slightly reduced.

[0038] In Comparative Example 2, compared to Example 1, the compatibilizer PP-g-MAH was not added, resulting in slightly worse compatibility between polypropylene and polystyrene, and a decrease in the physical properties of the composition.

[0039] In Example 1, compared to Comparative Example 4, nano-compatibilization improved the compatibility between polystyrene and polypropylene, reducing the shrinkage rate of the polystyrene-added polypropylene, increasing its impact resistance and strength, and resulting in optimized and improved performance.

[0040] The above description of embodiments is intended to enable persons with ordinary skill in the art to understand and use the present invention. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments without ingenuity, and that the general principles described herein can be applied to other embodiments. Therefore, the present invention is not limited to the embodiments described above, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the invention, are protected by the present invention.

Claims

1. A method for producing a nano-compatible polypropylene / polystyrene composition comprising, by weight, 60 to 80 parts of polypropylene resin, 20 to 40 parts of modified polystyrene nanofiber nonwoven fabric, 0.1 to 1 part of antioxidant, and 0.1 to 1 part of lubricant, The modified polystyrene nanofiber nonwoven fabric is a nanofiber nonwoven fabric with a fiber diameter of 100 to 600 nm obtained by electrospinning a polystyrene resin and a PP-g-MAH composition. The aforementioned polystyrene resin and PP-g-MAH composition comprises, by weight, 98 to 99 parts of polystyrene resin and 1 to 2 parts of PP-g-MAH. The modified polystyrene nanofiber nonwoven fabric is (1) A step of dissolving polystyrene resin and PP-g-MAH in DMF to prepare a solution with a polymer concentration of 15-25% by weight, (2) A process in which the solution obtained in step (1) is electrospinned, the electrospinning voltage is controlled to 25-35kV, the forward speed is controlled to 4-6μl / min, and the ambient temperature and humidity are controlled to 20-25°C and 25-35%, respectively. (3) A nanofiber nonwoven fabric manufactured by a process that includes the step of crushing the modified polystyrene nanofiber nonwoven fabric obtained in step (2) to obtain small pieces of nonwoven fabric, The mixture of the polypropylene resin, the modified polystyrene nanofiber nonwoven fabric, the antioxidant, and the lubricant is melt-extruded and then cooled and granulated. A method for producing a nano-compatible polypropylene / polystyrene composition characterized by the following:

2. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 1, characterized in that the melt index flow rate MI (200°C × 5 kg) of the polystyrene resin is 3 to 8 g / 10 min.

3. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 1, wherein the polypropylene resin comprises one or both of a copolymerized polypropylene resin and a homopolymerized polypropylene resin.

4. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 1, characterized in that the antioxidant is one or a mixture of several of the following: 2,6-di-tert-butyl-4-methylphenol, dilauryl thiodipropionate, thiodipropionate distearate, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butyl) quaternary tetrahydrol diphosphite, and pentaerythritol bisphosphite di(octadecanol) ester.

5. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 1, characterized in that the lubricant is a mixture of one or more of ethylene bis-stearamide, stearate, and silicone lubricants.

6. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 1, characterized in that a polypropylene resin, an antioxidant, and a lubricant are added to a mixer and thoroughly mixed, then placed into the main feed of a screw machine, and at the same time, a modified polystyrene nanofiber nonwoven fabric is added to the side supply port by weight reduction control, and then melt extrusion is performed at an extrusion temperature of 180 to 210°C and a screw speed of 200 to 500 rpm, followed by cooling and granulation.

7. A method for producing a nano-compatible polypropylene / polystyrene composition according to claim 6, characterized in that, during the manufacturing process, the temperature of the temperature control zone immediately preceding the side supply port is set to 100°C.

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