Extruded micro-foaming high-density polyethylene and preparation method and device thereof

Abstract

The invention relates to the technical field of foaming materials, and discloses extruded micro-foamed high-density polyethylene and a preparation method and device thereof, and the preparation method comprises the following steps: step 1, mixing raw materials containing high-density polyethylene, expanded microspheres, a filler and an interfacial compatibilizer to obtain a premix; and 2, drying the premix, carrying out melt blending extrusion, and carrying out high-temperature steam-assisted foaming. According to the invention, the expanded microspheres are used as a foaming agent, the expanded microspheres are subjected to micro-foaming during melt extrusion through melt blending extrusion and high-temperature steam assisted foaming, and then are subjected to secondary foaming through high-temperature steam, so that the effect of the expanded microspheres as a light filler and the foaming agent is fully exerted, and a highly controllable and stable foaming effect is realized; a fine and uniform foam structure is obtained in the material, and the polyethylene foam material with relatively high mechanical property and foaming ratio is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of foaming materials, and in particular to an extruded micro-foamed high-density polyethylene and a preparation method and a device thereof. Background Art

[0002] The molecular structure of high-density polyethylene is mainly linear, with high crystallinity, high operating temperature, mechanical strength and chemical resistance, and can be used to produce products in the fields of pipes, home furnishings, etc. In the context of carbon neutrality, in order to achieve the goals of carbon reduction and weight reduction, microporous structures are usually introduced into high-density polyethylene to reduce material costs, improve the performance of polyethylene foam materials, and expand the application areas of polyethylene foam materials.

[0003] Chinese invention patent CN102229708A discloses a high-foaming ratio high-density polyethylene microporous foam profile and its preparation method. The characteristics are that the foam profile is directly prepared by physical gas foaming method using high-density polyethylene raw material in the presence of physical gas foaming agent, and its foaming density is 0.032-0.20g / cm 3 The expansion ratio is 5-30 times, the average pore size of the pores is 10-120μm, the pores are evenly distributed, and the diameter deviation of 95% of the pores does not exceed 15% of the average pore size. There is no skin structure and the material can be of any shape. This high-expansion ratio high-density polyethylene microporous foam material has the characteristics of high mechanical strength, good resilience, good heat resistance, good chemical corrosion resistance, and waste recyclability, which can make up for the shortcomings of existing foaming materials.

[0004] Chinese invention patent CN103554626A discloses a micro-foamed polyethylene-based wood-plastic composite material and its preparation method. The micro-foamed polyethylene-based wood-plastic composite material is prepared by stirring and heating the matrix polyethylene resin, modified wollastonite powder and talcum powder, cross-linking agent, lubricant, heat-balanced foaming agent, antioxidant, UV inhibitor, pigment, and modified plant fiber, mixing them evenly and then cooling and unloading to obtain a premix. The modified plant fiber is selected from a mixture of one or more of wood powder, bamboo powder, and rice husk powder in any proportion; the premix is ​​placed in an extruder for granulation, extrusion foaming, and cooling and shaping. By adding high-filling plant fiber, a density of 0.81~0.91g / cm 3 , flexural strength 16.56~17.54MPa micro-foamed polyethylene-based wood-plastic composite material.

[0005] How to reduce density while maintaining high strength is a common problem for foaming materials. As the number of cells in the foaming material increases, the gas filling amount increases, the density gradually decreases, but the fulcrum also decreases, and the mechanical strength decreases. In addition, when high-filling fillers are added to the polymer matrix, there are problems of poor compatibility and difficulty in foaming, which affects the foaming performance and mechanical properties of microporous foaming materials and limits the application range of the materials. Summary of the invention

[0006] Aiming at the problem that the foaming property and mechanical property of micro-foamed resin cannot be achieved simultaneously, the present invention provides a method for preparing extruded micro-foamed high-density polyethylene. By combining extrusion and high-temperature steam-assisted foaming, a polyethylene foam material with both mechanical property and high foaming density property can be prepared with a low amount of foaming filler.

[0007] To achieve the above object, the technical solution adopted by the present invention is: A method for preparing extruded micro-foamed high-density polyethylene comprises the following steps: Step 1, mixing raw materials including high-density polyethylene, expanded microspheres, fillers, and interfacial compatibilizers to obtain a premix; Step 2, drying the premix, melt blending and extruding, foaming the molten mixture leaving the die with the aid of high temperature steam, cooling and shaping, drying and cutting to obtain the extruded micro-foamed high-density polyethylene; The raw materials include, by weight: 65-95 parts of high-density polyethylene, 3-15 parts of expanded microspheres, 1-15 parts of fillers, and 1-3 parts of interfacial compatibilizers.

[0008] In the present invention, expanded microspheres are used as foaming agents, and through melt blending extrusion and high-temperature steam assisted foaming, the expanded microspheres are micro-foamed during melt extrusion, and then further foamed by high-temperature steam, giving full play to the role of expanded microspheres as lightweight fillers and foaming agents, achieving a highly controllable and stable foaming effect, and obtaining a fine and uniform pore structure inside the material. No excessive amount of chemical foaming agents is required, and no complicated N 2 or CO 2 Physical foaming technology such as PE foam material with high mechanical properties and foaming ratio is produced.

[0009] The high-temperature steam-assisted foaming in the present invention is to foam the molten mixture through an extrusion channel into which high-temperature steam is continuously introduced; The high-temperature steam is saturated water vapor with a temperature of 85-230° C. and an absolute pressure of 57.88-2798.59 kPa.

[0010] Preferably, the temperature of the high-temperature steam is not lower than the puffing temperature of the puffed microspheres.

[0011] The expanded microspheres are at least one of dry unexpanded microspheres, dry expanded microspheres, wet unexpanded microspheres, and wet expanded microspheres.

[0012] The expanded microspheres are Nouryon's expanded microspheres Expancel, such as any one or more of 920 DU20, 950 DU80, 044 DU40, 980 DU100, 031 DU40 and other models.

[0013] The filler includes at least one of talc, attapulgite, calcium carbonate, modified wollastonite, carbon black, white carbon black, boron nitride, aluminum nitride, aluminum oxide, diatomaceous earth, zirconium phosphate, montmorillonite, activated clay, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, kaolin, silicon oxide, glass powder, and silicon dioxide.

[0014] The high-density polyethylene includes at least one of high-density polyethylene powder, high-density polyethylene pellets or high-density polyethylene recycled materials.

[0015] The raw materials also include one or more additives such as pigments, UV inhibitors, and antioxidants, and the dosage of each additive is 0.1-5 parts. Other additives can be added to the raw materials according to the actual application scenarios to improve the antioxidant and anti-aging properties of the materials.

[0016] The pigment includes at least one of masterbatch, carbon black, titanium dioxide, red iron oxide or yellow iron oxide; The interfacial compatibilizer includes at least one of maleic anhydride grafted polyethylene, acrylic acid grafted polyethylene, or acrylic acid grafted metallocene ethylene-1-octene copolymer; The anti-ultraviolet agent includes 2-hydroxy-4-n-octyloxybenzophenone UV531; The antioxidant includes at least one of a hindered phenol antioxidant 1010 and a phosphite antioxidant 168 .

[0017] The temperature of the melt blending is 110-160° C.; the die for melt blending extrusion is one of a strip die, a T-shaped die, a circular die or a tubular die.

[0018] The present invention also provides an extruded micro-foamed high-density polyethylene obtained by the preparation method, wherein the density of the extruded micro-foamed high-density polyethylene is 0.50-0.80 g / cm 3 ; Static bending strength is above 9.5MPa.

[0019] The invention also provides a device for extruding micro-foamed high-density polyethylene, comprising a screw extruder and a steam-assisted foaming device; the steam-assisted foaming device is connected to the extrusion die of the screw extruder and is provided with a steam inlet and a steam outlet.

[0020] The screw extruder includes a single screw or a twin screw extruder.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation method of the present invention uses an extruder with high-temperature steam-assisted foaming, and the pore structure can be customized by controlling the decomposition temperature of the expanded microspheres. The product pore structure is uniform and the material has high mechanical strength.

[0022] (2) The extruded micro-foamed high-density polyethylene material of the present invention uses a series of expanded microspheres, without the need to add chemical foaming agents or modify equipment to implement N 2 or CO 2 Physical foaming technology has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the equipment structure of the extruded micro-foamed high-density polyethylene of the present invention, wherein 1 is a screw extrusion device, 2 is a feed port, 3 is an extrusion screw, 4 is a mixed material, 5 is an extrusion die, 6 is a steam-assisted foaming device, and 7 is an extruded micro-foamed high-density polyethylene material.

[0024] Figure 2 It is a schematic diagram of the cross-sectional structure of the high-temperature steam-assisted foaming device of the present invention.

[0025] Figure 3 This is a SEM image of the microporous structure of the extruded micro-foamed high-density polyethylene prepared in Example 1.

[0026] Figure 4 This is the SEM image of the microporous structure of the extruded micro-foamed high-density polyethylene prepared in Comparative Example 1. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical scheme of the present invention without departing from the spirit and scope of the technical scheme of the present invention, and all should be included in the protection scope of the present invention.

[0028] The raw materials used in the following specific embodiments are all purchased from the market, wherein the high-density polyethylene is specifically the high-density polyethylene produced by Yanshan Petrochemical and Saudi Basic Company, the expanded microspheres are specifically the expanded microspheres Expancel series produced by Nouryon, the interfacial compatibilizer is the maleic anhydride compound grafted polyethylene PE-g-MAH series, the acrylic acid compound grafted polyethylene PAA-g-PE series or the acrylic acid compound grafted metallocene ethylene-1-octene copolymer PAA-g-MAH series, the hindered phenol antioxidant 1010 or the phosphite antioxidant 168, and the UV inhibitor includes 2-hydroxy-4-n-octyloxybenzophenone UV531.

[0029] The device and basic preparation process of extruded micro-foamed high-density polyethylene are as follows: A device for extruding micro-foamed high-density polyethylene Figure 1 As shown, it includes a screw extruder 1 and a steam-assisted foaming device 6; the cross section of the steam-assisted foaming device 6 is as shown Figure 2 As shown, it is connected to the extrusion die 5 of the screw extruder and is provided with a steam inlet A1 and a steam outlet A2.

[0030] When preparing micro-foamed high-density polyethylene, the mixed material 4 enters the extrusion screw 3 from the feed port 2, is melt-mixed and extruded from the extrusion die 5, and is immersed in the steam-assisted foaming device. High-temperature steam enters from the steam inlet A1 and leaves through the steam outlet A2, acting on the molten mixture to promote secondary foaming to obtain the extruded micro-foamed high-density polyethylene material 7.

[0031] Example 1 Step 1, weighing 60 parts by weight of high-density polyethylene powder, 20 parts by weight of high-density polyethylene recycled material, 10 parts by weight of dry unexpanded microspheres Expancel 950 DU80, 6 parts by weight of attapulgite, 1 part by weight of masterbatch, 2 parts by weight of interfacial compatibilizer (PAA-g-PE), 0.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a T-type extrusion die, the extrusion die width is 20CM and the thickness is 3cm, controlling the melt temperature in the extruder to be around 130°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 180°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0032] The microscopic morphology of the extruded micro-foamed high-density polyethylene material prepared in this example is shown in SEM. Figure 3 As shown, the pores are uniform and the material density is 0.68 g / cm 3The static bending strength is 11.6MPa according to GB / T 9341-2008 test.

[0033] Example 2 Step 1, weighing about 85 parts by weight of high-density polyethylene pellets, 5 parts by weight of wet unexpanded microspheres Expancel921 WE40, 5 parts by weight of calcium carbonate, 2 parts by weight of masterbatch, 2 parts by weight of interfacial compatibilizer (PE-g-MAH), 0.4 parts by weight of antioxidant 168, and 0.6 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a circular extrusion die with a diameter of 1 cm, controlling the melt temperature in the extruder to be around 115°C for extrusion processing to obtain a molten mixture, subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 200°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0034] The density of the extruded micro-foamed high-density polyethylene prepared in this example is 0.74 g / cm 3 , the static bending strength is 14.8MPa.

[0035] Example 3 Step 1, weighing about 70 parts by weight of high-density polyethylene recycled material, 15 parts by weight of dry expanded microspheres Expancel 920DU 40, 10 parts by weight of barium carbonate, 1 part by weight of masterbatch, 1 part by weight of interfacial compatibilizer (PAA-g-POE), 1 part by weight of antioxidant 1010, and 2 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 3, adding the premix into an extruder, a T-shaped extrusion die, an extrusion die width of 50CM and a thickness of 10cm, controlling the melt temperature in the extruder to be around 160°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 160°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0036] The density of the extruded micro-foamed high-density polyethylene prepared in this example is 0.75 g / cm 3 , the static bending strength is 12.5MPa.

[0037] Example 4 Step 1, weighing about 68 parts by weight of high-density polyethylene recycled material, 10 parts by weight of high-density polyethylene powder, 12 parts by weight of dry expanded microspheres Expancel 920 DU 120, 7 parts by weight of barium carbonate, 1 part by weight of masterbatch, 1 part by weight of interfacial compatibilizer (PAA-g-PE), 0.5 parts by weight of antioxidant 168, and 0.5 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into an extruder, a T-shaped extrusion die, an extrusion die width of 10CM and a thickness of 2cm, controlling the melt temperature in the extruder to be around 135°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 200°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0038] The density of the extruded micro-foamed high-density polyethylene prepared in this example is 0.65 g / cm 3 , the static bending strength is 11.9MPa.

[0039] Comparative Example 1 Step 1, weighing about 70 parts by weight of high-density polyethylene powder, 20 parts by weight of high-density polyethylene recycled material, 6 parts by weight of attapulgite, 1 part by weight of masterbatch, 2 parts by weight of interfacial compatibilizer (PAA-g-PE), 0.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a T-type extrusion die, the extrusion die width is 20CM and the thickness is 3cm, controlling the melt temperature in the extruder to be around 130°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 180°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0040] The extruded micro-foamed high-density polyethylene prepared in this embodiment has no obvious pores, and its microscopic morphology is as follows Figure 4 , and the density is relatively high. Due to the lack of expanded microspheres, there is no obvious weight loss effect, and the density is 0.92 g / cm 3 , the static bending strength is 13.8MPa.

[0041] Comparative Example 2 Step 1, weighing about 60 parts by weight of high-density polyethylene powder, 20 parts by weight of high-density polyethylene recycled material, 10 parts by weight of dry unexpanded microspheres Expancel 950 DU80, 6 parts by weight of attapulgite, 1 part by weight of masterbatch, 2 parts by weight of interfacial compatibilizer (PAA-g-PE), 0.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a T-shaped extrusion die with a width of 20 cm and a thickness of 3 cm, controlling the melt temperature in the extruder to be around 130°C for extrusion processing to obtain a molten mixture; the molten mixture is allowed to foam freely after leaving the die, cooled and shaped, and cut to obtain an extruded micro-foamed high-density polyethylene material.

[0042] The extruded micro-foamed high-density polyethylene prepared in this embodiment has uniform pores, but without the auxiliary foaming of high-temperature steam, the density is still relatively large, and the foaming effect is not obvious. The density is 0.88 g / cm 3 , there is no obvious weight reduction effect, and the static bending strength is 13.1MPa.

[0043] Comparative Example 3 Step 1, weighing about 66 parts by weight of high-density polyethylene powder, 20 parts by weight of high-density polyethylene recycled material, 10 parts by weight of dry unexpanded microspheres Expancel 950 DU80, 1 part by weight of masterbatch, 2 parts by weight of interfacial compatibilizer, 0.5 parts by weight of antioxidant, and 0.5 parts by weight of anti-ultraviolet agent, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a T-type extrusion die, the extrusion die width is 20CM and the thickness is 3cm, controlling the melt temperature in the extruder to be around 130°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to high-temperature steam-assisted foaming at 180°C, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0044] The extruded micro-foamed high-density polyethylene prepared in this example has uniform pores and a density of 0.62 g / cm 3 The static bending strength is 8.2MPa, but without adding fillers, the mechanical strength is low.

[0045] Comparative Example 4 Step 1, weighing 60 parts by weight of high-density polyethylene powder, 20 parts by weight of high-density polyethylene recycled material, 10 parts by weight of dry unexpanded microspheres Expancel 950 DU80 (the expansion temperature of this series of products is 136-200°C), 6 parts by weight of attapulgite, 1 part by weight of masterbatch, 2 parts by weight of interfacial compatibilizer (PAA-g-PE), 0.5 parts by weight of antioxidant 1010, and 0.5 parts by weight of anti-ultraviolet agent UV531, and uniformly mixing to obtain a premix; Step 2, adding the premix into the extruder, selecting a T-type extrusion die, the extrusion die width is 20CM and the thickness is 3cm, controlling the melt temperature in the extruder to be around 130°C for extrusion processing to obtain a molten mixture; subjecting the molten mixture leaving the die to 80°C high-temperature steam-assisted foaming, cooling and shaping, drying, and cutting to obtain an extruded micro-foamed high-density polyethylene material.

[0046] Since the steam temperature is lower than the expansion temperature of the expanded microspheres, the extruded micro-foamed high-density polyethylene material prepared in this embodiment has no obvious cellular structure and the material density is 0.90 g / cm 3 , the static bending strength is 13.1MPa.

[0047] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing extruded micro-foamed high-density polyethylene, characterized in that: Includes steps: Step 1, mixing raw materials including high-density polyethylene, expanded microspheres, fillers, and interfacial compatibilizers to obtain a premix; Step 2, drying the premix, melt blending and extruding, foaming the molten mixture leaving the die with the aid of high temperature steam, cooling and shaping, drying and cutting to obtain the extruded micro-foamed high-density polyethylene; The raw materials include, by weight: 65-95 parts of high-density polyethylene, 3-15 parts of expanded microspheres, 1-15 parts of fillers, and 1-3 parts of interfacial compatibilizers.

2. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The high-temperature steam-assisted foaming is to foam the molten mixture through an extrusion channel into which high-temperature steam is continuously introduced; The high-temperature steam is saturated water vapor with a temperature of 85-230° C., and the absolute pressure of the saturated water vapor is 57.88-2798.59 kPa.

3. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The expanded microspheres are at least one of dry unexpanded microspheres, dry expanded microspheres, wet unexpanded microspheres, and wet expanded microspheres.

4. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The expanded microspheres are Expancel microspheres produced by Nouryon.

5. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The filler includes at least one of talc, attapulgite, calcium carbonate, modified wollastonite, carbon black, white carbon black, boron nitride, aluminum nitride, aluminum oxide, diatomaceous earth, zirconium phosphate, montmorillonite, activated clay, magnesium carbonate, barium carbonate, calcium sulfate, magnesium sulfate, kaolin, silicon oxide, glass powder, and silicon dioxide; The interfacial compatibilizer includes at least one of maleic anhydride grafted polyethylene, acrylic acid grafted polyethylene, or acrylic acid grafted metallocene ethylene-1-octene copolymer.

6. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The raw materials also include one or more auxiliary agents selected from the group consisting of pigments, anti-ultraviolet agents, and antioxidants, and the dosage of each auxiliary agent is 0.1-5 parts.

7. The method for preparing extruded micro-foamed high-density polyethylene according to claim 6, characterized in that: The pigment includes at least one of masterbatch, carbon black, titanium dioxide, red iron oxide or yellow iron oxide; The anti-ultraviolet agent includes 2-hydroxy-4-n-octyloxybenzophenone UV531; The antioxidant includes at least one of a hindered phenol antioxidant 1010 and a phosphite antioxidant 168 .

8. The method for preparing extruded micro-foamed high-density polyethylene according to claim 1, characterized in that: The temperature of the melt blending is 110-160° C.; the die for melt blending extrusion is one of a strip die, a T-shaped die, a circular die or a tubular die.

9. The extruded micro-foamed high-density polyethylene obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The density of the extruded micro-foamed high-density polyethylene is 0.50-0.80 g / cm 3 ; Static bending strength is above 9.5MPa.

10. A device for extruding micro-foamed high-density polyethylene, characterized in that: The invention comprises a screw extrusion device and a steam-assisted foaming device; the steam-assisted foaming device is connected with the extrusion die of the screw extrusion device and is provided with a steam inlet and a steam outlet.

Images