Polypropylene micro-foam material and its manufacturing method and use

Abstract

This invention discloses a polypropylene microcellular foam and its manufacturing method and use. The polypropylene microcellular foam contains polypropylene, sodium maleate-grafted poly-1-butene, ethylene-octene random copolymer, filler, lubricant, and antioxidant. In this invention, the combination of polypropylene with an appropriate melt index and ethylene-octene random copolymer ensures smooth foaming of the material. Furthermore, the addition of sodium maleate-grafted poly-1-butene significantly improves the interfacial adhesion between the filler and polypropylene due to its unique low melting point and polar graft modification, further enhancing foam molding. The polypropylene microcellular foam obtained by adding a blowing agent and extruding the foam exhibits excellent appearance, dense and uniform cells (grade 1), a high closed cell rate of 92.3%-94.3%, a weight loss rate of 22.7%-27.2%, and a density of 0.661-0.928 g / cm after foaming. 3 reaches.

Description

[Technical Field]

[0001] The present invention relates to the field of polypropylene materials, and in particular to polypropylene microcellular foams and their methods of manufacture and use. [Background technology]

[0002] Polypropylene (PP) is a crystalline polymer with a regular structure. It is an odorless, non-toxic, lightweight thermoplastic resin that usually exists as white particles or powder. It has advantages such as ease of processing, impact strength, flexibility, and electrical insulation, as well as excellent chemical resistance. It is widely used in the automotive industry, home appliances, electronics, packaging, building materials, and furniture.

[0003] With the trend toward lightweighting in industries such as automobiles, foaming has become an important method for achieving this. Among these, micro-foamed polypropylene (EPP) has attracted significant attention and has been extensively studied for use in interior and exterior components such as door panels, interior door handles, and seat guide guards. Expanded polypropylene (EPP) is a highly crystalline polymer / gas composite with excellent performance. Its unique and outstanding properties have made it the fastest-growing new, environmentally friendly pressure-resistant, buffer, and insulating material. EPP products offer excellent impact absorption, a high recovery rate after deformation, excellent heat resistance, chemical resistance, oil resistance, and thermal insulation properties. Furthermore, their lightweight design significantly reduces the mass of products. Furthermore, EPP is an environmentally friendly material that is prone to beta-cleavage. PP foam is easily recyclable and more environmentally friendly than other foam materials, earning it the nickname "green" foam. Due to its excellent performance, expanded polypropylene materials are becoming a new foam material with greater application value and market potential, following polystyrene (EPS) and polyurethane (EPU) foam materials. However, conventional foamed polypropylene materials have drawbacks such as an orange peel-like appearance, poor bubble uniformity, and a tendency for bubble fusion and bubble bursting. Summary of the Invention [Problem to be solved by the invention]

[0004] In light of this, the present invention overcomes the drawbacks of the prior art and provides a polypropylene microcellular foam, a manufacturing method thereof, and uses thereof. The polypropylene microcellular foam is extruded and foamed with a blowing agent, resulting in a product with good appearance, dense and uniform cells, a high closed cell rate of 92% or more, and a high weight loss rate after foaming. [Means for solving the problem]

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A polypropylene micro-foam material, comprising, as components, 45-96 parts by weight of polypropylene, 1-5 parts by weight of sodium maleate grafted poly-1-butene, 2-10 parts by weight of ethylene-octene random copolymer, 3-40 parts by weight of filler, 0.1-0.4 parts by weight of lubricant, and 0.1-0.4 parts by weight of antioxidant; The polypropylene has a melt index of 0.5 to 3 g / 10 min measured under conditions of 230°C and 2.16 kg in accordance with measurement standard ISO 1133-1 / 2: 2012. If the melt index of the polypropylene is too low, its melt strength will be too high, resulting in poor foaming effect, while if the melt index is too high, its melt strength will be too low, resulting in defects such as bubble bursting and bubble fusion.

[0006] The ethylene-octene random copolymer has a melt index of 5 to 13 g / 10 min measured under the conditions of 190°C and 2.16 kg in accordance with the measurement standard ISO 1133-1 / 2:2012. Octene has a high molecular weight and exhibits excellent entanglement with polypropylene, achieving good foaming while preventing cell rupture due to insufficient ductility. If the ethylene-octene random copolymer has a melt index that is too high, cell fusion occurs during foaming, while if the melt index is too low, the foaming effect is poor.

[0007] Preferably, the polypropylene micro-foamed material contains, as components, 53 to 62 parts by weight of polypropylene, 2 to 3 parts by weight of sodium maleate-grafted poly-1-butene, 5 to 7 parts by weight of ethylene-octene random copolymer, 10 to 30 parts by weight of filler, 0.1 to 0.4 parts by weight of lubricant, and 0.1 to 0.4 parts by weight of antioxidant; Preferably, the filler is at least one of talc, calcium carbonate, and basic magnesium sulfate whiskers.

[0008] Preferably, the lubricant is a stearate.

[0009] Preferably, the antioxidant is a hindered phenol and / or a phosphite.

[0010] In this application, sodium maleate-grafted poly-1-butene with a melting point of 104°C is used, which is much lower than that of ordinary maleic anhydride-grafted polypropylene (melting point 165°C). Its unique low melting point and polar graft modification can significantly improve the interfacial adhesion between the filler and polypropylene, solving the problems of uneven bubble formation and bubble bursting, and providing greater advantages for foam molding.

[0011] Preferably, the sodium maleate-grafted poly-1-butene is produced by the following method: Poly-1-butene, sodium maleate, and an antioxidant are uniformly mixed to obtain a mixture; an initiator, α-methylstyrene (AMS), and 1-octene are dissolved in acetone, and the resulting mixture is uniformly mixed with the resulting mixture; after the acetone has evaporated, the resulting mixture is melted and extruded to carry out a grafting reaction, thereby obtaining sodium maleate-grafted poly-1-butene. The graft ratio of the sodium maleate-grafted poly-1-butene is 0.8 to 1.5%.

[0012] Preferably, the initiator is di-tert-butyl peroxide (DTBP).

[0013] Preferably, the antioxidant is a hindered phenol and / or a phosphite antioxidant.

[0014] Preferably, in the production of the sodium maleate-grafted poly-1-butene, the amounts of each component used are 100 parts by weight of poly-1-butene, 1.5 to 4.5 parts by weight of sodium maleate, 0.2 to 0.4 parts by weight of antioxidant, 0.2 to 0.4 parts by weight of initiator, 2 to 3 parts by weight of α-methylstyrene, and 1 to 1.5 parts by weight of 1-octene.

[0015] Preferably, a twin-screw extruder is used for the melt extrusion, and the temperature is set to 135 to 150°C.

[0016] Preferably, the sodium maleate-grafted poly-1-butene is purified by the following method: dissolving the sodium maleate-grafted poly-1-butene in xylene, then precipitating it with acetone, washing and drying the precipitate to obtain a primary purified product, and repeating the above purification process to obtain purified sodium maleate-grafted poly-1-butene.

[0017] The method for producing the polypropylene micro-foamed material includes the steps of uniformly mixing the components, melting and extruding the mixture, granulating the mixture, adding a foaming agent, and extruding the mixture to foam the mixture, thereby obtaining the polypropylene micro-foamed material.

[0018] Preferably, a 75D co-rotating twin-screw extruder is used for the melt extrusion and granulation, with temperatures ranging from the feed zone to the head in order of 170°C, 200°C, 200°C, 210°C, 210°C, 205°C, 205°C, 205°C, 200°C, and 200°C.

[0019] Preferably, the amount of the foaming agent added is 1 to 3% of the polypropylene micro-foam material.

[0020] Use of the above polypropylene micro-foam material in the production of pressure-resistant buffer insulation materials such as car seat side guards and spare tire covers for car trunks. [Effects of the Invention]

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention combines polypropylene with an appropriate melt index and an ethylene-octene random copolymer to ensure smooth foaming. The addition of sodium maleate-grafted poly-1-butene significantly improves the interfacial adhesion between the filler and polypropylene due to its unique low melting point and polar graft modification, further enhancing foam molding. The products obtained by adding a blowing agent to a polypropylene micro-foam material and extruding the foam exhibit excellent appearance, dense, uniform, and first-class foaming, with a high closed cell rate of 92.3% to 94.3%, a weight loss rate of 22.7% to 27.2%, and a foamed density of 0.661 to 0.928 g / cm. 3 The polypropylene micro-foam material of the present invention can be produced by a simple process and is suitable for mass production. DETAILED DESCRIPTION OF THE INVENTION

[0023] In order to better illustrate the objectives, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific examples.

[0024] In the examples, unless otherwise specified, the experimental methods used are conventional methods, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0025] In the following examples and comparative examples, unless otherwise specified, the antioxidants and lubricants were commercially available, and the same antioxidants and lubricants were used in parallel experiments.

[0026] The melt index of the following PP is measured at 230°C and 2.16 kg in accordance with the measurement standard ISO 1133-1 / 2:2012.

[0027] The melt index of the following ethylene-octene random copolymer is measured under the measurement conditions of 190°C and 2.16 kg in accordance with the measurement standard ISO 1133-1 / 2:2012.

[0028] The raw materials used in the examples and comparative examples are as follows.

[0029] PP-1: B8101 (copolymer, melt index 0.5 g / 10 min), manufactured by Yanshan Petrochemical Co., Ltd. PP-2: K8303 (copolymer, melt index 3g / 10min), manufactured by Yanshan Petrochemical Co., Ltd. PP-3: EP548R (copolymer, melt index 30g / 10min), manufactured by Shell Petrochemical Co., Ltd. PP-4: R4220 (copolymer, melt index 0.3 g / 10 min), manufactured by Yanshan Petrochemical Co., Ltd. Maleic anhydride grafted polypropylene: PC-1, manufactured by Foshan Nanhai Bochen Co., Ltd. Calcium carbonate: 75T, manufactured by Choko Europe Asia Co., Ltd. Basic magnesium sulfate whiskers: WS-1S2, manufactured by Yingkou Kangru Technology Co., Ltd. Talc: AH-51210, 3000 mesh, manufactured by Liaoning AH Group Ethylene-octene random copolymer: 8842 (melt index 1g / 10min), manufactured by Dow Chemical Company, USA Ethylene-octene random copolymer: 8200 (melt index 5g / 10min), manufactured by Dow Chemical Company, USA Ethylene-octene random copolymer: 8407 (melt index 30 g / 10 min), manufactured by Dow Chemical Company, USA Ethylene-octene random copolymer: 8137 (melt index 13 g / 10 min), manufactured by Dow Chemical Company, USA Thermoplastic elastomer SEBS:G1657, manufactured by Dow Chemical Company, USA Hindered phenolic antioxidant: SONOX 1010, commercially available Phosphite ester antioxidant: SONOX 168, commercially available Zinc stearate: BS-2818, commercially available Inorganic foaming agent: EE25C, manufactured by Nippon Eiwa Fine Chemicals Co., Ltd.

[0030] Poly-1-butene grafted sodium maleate (PB-1-g-sodium maleate) is produced by the following method. Poly-1-butene, sodium maleate, and antioxidant 168 are mixed uniformly to obtain a mixture. The initiator di-tert-butyl peroxide (DTBP), α-methylstyrene (AMS), and 1-octene are dissolved in acetone and mixed uniformly with the mixture. After the acetone has evaporated, the mixture is melted and extruded at 150°C in a twin-screw extruder to carry out the graft reaction, yielding sodium maleate grafted poly-1-butene. The amounts of each component used are 100 parts by weight of poly-1-butene, 3 parts by weight of sodium maleate, 0.3 parts by weight of antioxidant, 0.2 parts by weight of di-tert-butyl peroxide, 3 parts by weight of α-methylstyrene, and 1.5 parts by weight of 1-octene. The resulting sodium maleate grafted poly-1-butene is purified as follows. That is, sodium maleate-grafted poly-1-butene was dissolved in xylene, then precipitated with acetone, and the precipitate was washed and dried to obtain a primary purified product. The above purification process was repeated twice to obtain purified sodium maleate-grafted poly-1-butene (grafting rate 1.2%), which was used to produce polypropylene microcellular foam. Examples and Comparative Examples

[0031] The components, amounts used, and performance of the polypropylene micro-foam materials used in the examples and comparative examples are shown in Tables 1 and 2.

[0032] The method for producing the polypropylene micro-foam material in the examples and comparative examples includes the following steps.

[0033] All ingredients except the foaming agent were added to a high-speed mixer and mixed for 3 minutes. The mixer was set to a rotation speed of 800 rpm. The mixed ingredients were added to a 75D co-rotating twin-screw extruder, melted, extruded, granulated, dried, and cooled to obtain a polypropylene microcellular foam. The twin-screw extruder was maintained at temperatures of 170°C, 200°C, 200°C, 210°C, 210°C, 205°C, 205°C, 205°C, 200°C, and 200°C from the feed zone to the head. The polypropylene microcellular foam was uniformly mixed with 2% inorganic foaming agent, foamed, and extruded into a 100 x 100 x 2 mm square plate by injection molding, and performance testing was performed. Performance Test

[0034] Performance tests were carried out on the products of the examples and comparative examples, and the specific test methods were as follows.

[0035] Appearance: The surface of a 100 x 100 mm square plate is observed with the naked eye, and the number of defects such as orange peel is counted. Excellent: 0 orange peel spots found Good: 1 to 3 orange peel spots Normal: Orange peel is visible in 4-6 places

[0036] Cell density and uniformity: The cell size of a 100 x 100 mm square plate was measured in accordance with GB / T 12811-1991. Class 1: 0~20μm Class 2: 21~40μm Grade 3: 41~60μm Grade 4: 61~80μm Grade 5: 81~100μm Grade 6: 101~120μm Grade 7: 121~140μm Cannot be foamed Foaming and bursting

[0037] Density: Measured in accordance with ISO 1183-1:2019.

[0038] Weight loss rate: [(density before foaming - density after foaming) / density before foaming] x 100%

[0039] Closed cell ratio: GB / T 10799-2008 Measurements were made in accordance with the

[0040] [Table 1]

[0041] [Table 2]

[0042] As can be seen from the results, the polypropylene microcellular foam of Comparative Example 1 did not contain sodium maleate-grafted poly-1-butene. The product had significantly lower weight loss and closed cell ratio than Example 1, poor cell density and uniformity, and a fair appearance. The polypropylene microcellular foam of Comparative Example 2 was extrusion foamed using polypropylene with a melt index of 30 g / 10 min. The product had significantly lower weight loss and closed cell ratio than Example 1, poor cell density and uniformity, and a good appearance. The polypropylene microcellular foam of Comparative Example 3 used maleic anhydride-grafted polypropylene instead of sodium maleate-grafted poly-1-butene. The product had significantly lower weight loss and closed cell ratio than Example 1, poor cell density and uniformity, and a fair appearance. Comparative Examples 4 and 5 used ethylene-butene random copolymers with melt indices of 1 g / 10 min and 30 g / 10 min, respectively. The weight loss rate and closed cell rate of the product were lower than those of Example 1, and the appearance was "good." Furthermore, in Comparative Example 4, the density and uniformity of the cells were poor, and in Comparative Example 5, the density and uniformity of the cells were also poor. In Comparative Example 6, SEBS was used instead of the ethylene-octene random copolymer. Sink marks occurred on the surface of the product, and the density and uniformity of the cells were poor. In Comparative Example 7, the amount of PB-1-g-sodium maleate used was too small, so the weight loss rate and closed cell rate of the product were lower than those of Example 1, the appearance was "good," and the density and uniformity of the cells were poor. In Comparative Example 8, the amount of ethylene-octene random copolymer used was too small, so the weight loss rate and closed cell rate of the product were lower than those of Example 1, the appearance was "good," and the density and uniformity of the cells were poor. .Compare In Comparative Example 9, the amount of sodium maleate-grafted poly-1-butene used was too large, resulting in poor cell density and uniformity, and the appearance was "average." In Comparative Example 10, extrusion foaming was performed using polypropylene with a melt index of 0.3 g / 10 min, which made molding difficult, resulted in a small weight loss rate, and a low closed cell rate.

[0043] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and do not limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A polypropylene micro-foam material, The composition comprises 45 to 96 parts by weight of polypropylene, 1 to 5 parts by weight of sodium maleate grafted poly-1-butene, 2 to 10 parts by weight of an ethylene-octene random copolymer, 3 to 40 parts by weight of a filler, 0.1 to 0.4 parts by weight of a lubricant, and 0.1 to 0.4 parts by weight of an antioxidant; The melt index of the polypropylene is 0.5 to 3 g / 10 min, The polypropylene micro-foam material is characterized in that the melt index of the ethylene-octene random copolymer is 5 to 13 g / 10 min.

2. 2. The polypropylene micro-foamed material according to claim 1, comprising, as components, 53 to 62 parts by weight of polypropylene, 2 to 3 parts by weight of sodium maleate-grafted poly-1-butene, 5 to 7 parts by weight of an ethylene-octene random copolymer, 10 to 30 parts by weight of a filler, 0.1 to 0.4 parts by weight of a lubricant, and 0.1 to 0.4 parts by weight of an antioxidant.

3. 3. The polypropylene micro-foam material according to claim 1, wherein the filler is at least one of talc, calcium carbonate, and basic magnesium sulfate whiskers.

4. 3. The polypropylene micro-foam material according to claim 1, wherein the lubricant is a stearate salt.

5. 3. The polypropylene micro-foam material according to claim 1, wherein the antioxidant is a hindered phenol and / or a phosphite ester.

6. A method for producing the polypropylene micro-foamed material according to any one of claims 1 to 5, A manufacturing method comprising the steps of uniformly mixing the components, melting and extruding the mixture, granulating the mixture, adding a foaming agent, and foaming the mixture by extrusion to obtain a polypropylene micro-foamed material.

7. 7. The method for producing a polypropylene micro-foamed material according to claim 6, wherein the amount of the foaming agent added is 1 to 3 wt % of the polypropylene micro-foamed material.

8. Use of the polypropylene micro-foam material according to any one of claims 1 to 5 in the production of a pressure-resistant cushioning insulating material.

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