Preparation method of continuous high-melt-strength polypropylene based on grafting reaction

Abstract

The invention relates to a preparation method of a continuous high-melt-strength polypropylene based on a grafting reaction. The continuous high-melt-strength polypropylene comprises the following components: 100 parts by weight of polypropylene, 0.01-1 part by weight of initiator, 0.1-5 parts by weight of a first grafting monomer and 0.1-5 parts by weight of a second grafting monomer. The first grafting monomer is a vinyl silicone oil compound, and the second grafting monomer is a C5-C10 monoolefin or polyene compound. The preparation method comprises the following steps: weighing the polypropylene, the initiator, the first grafting monomer and the second grafting monomer, adequately mixing the mixture, and then, adding the mixture to a twin-screw extruder, milling, extruding and granulating the mixture at 140-250 DEG C. The invention provides a method for preparing the high-melt-strength polypropylene which has no gelatin, has favorable color and luster and contains a long branch chain through a one-step silane method which has a simple process, flexibility in operation and an industrial implementation foreground, and a high-melt-strength polypropylene material obtained by the preparation method is applicable to the application fields of foaming, thermal forming, film blow molding, extrusion coating and the like.

Description

【Technical field】 [0001] The invention relates to the technical field of polypropylene, in particular to a method for preparing continuous high-melt strength polypropylene based on grafting reaction. 【Background technique】 [0002] Polypropylene (PP) is one of the most widely used and fastest growing resins in the world. However, the common commodity PP produced by Ziegler-Natta and metallocene catalysts has a linear structure, which leads to its relatively narrow molecular weight distribution, low melt strength and poor sag resistance, which greatly limits its use in foaming, Applications in thermoforming, blow molding, extrusion coating, etc. Therefore, improving the melt strength of PP is an important topic in the development of new PP products. [0003] At present, there are three main methods to improve the melt strength of PP: (1) Reactor modification method to increase the relative molecular weight of PP, that is, grafting reaction is carried out during the resin po...

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Problems solved by technology

[0006] Although the method of electron radiation is relatively common in industrial production at present, the process is complicated and the safety protection requirements are relatively high, so people are keen to use the method of reactive extrusion to develop

[0007] Chinese patent (publication number CN101125947A) has announced the method for preparing HMSPP by reaction of polypropylene graft (such as polypropylene grafted maleic anhydride) and molecule containing amino or hydroxyl functional group in screw extruder, although this process No gel is produced, but the color of the product is poor and the cost is high

M.Kster (M.Kster and G. Hellmann.Macromolecular Materials and Engineering, 2001, 286(12), 769-773) and Li, S (Li, S., et al. Polymer, 2009, 50(25), 6121-6128) etc. also adopt the reactive extrusion method to prepare PP-g-MAn and PP-g-GMA respectively with maleic anhydride (MAn) and glycidyl methacrylate (GMA) as grafting monomers, and then It and the polyfunctional chain extender with amino groups are again prepared by extrusion reaction with HMSPP containing long branched chain structure. Although this method does not contain gel, this method not only requires a second high temperature reaction extrusion process to affect product performance, but also The color of the product will turn yellow due to the presence of amino groups

[0008] Nachtigall, S (Nachtigall, S., et al. Journal of Applied Polymer Science, 1999, 72 (10), 1313-1319) etc. and Wang, Z (Wang, Z., et al. Polymer International, 2005, 54 ( 2), 442-447), etc., use vinyl siloxane as grafting monomer to prepare vinyl silane grafted polypropylene (PP-g-VTES) by reactive extrusion method, and then boil PP-g-VTES Cross-linking forms high-melt-strength polypropylene with long-chain branches and cross-linked structures. Although this method only requires one-step reaction extrusion, it needs to go through a subsequent water boiling process. The procedure is complicated and the thickness of the molded product is very high.

Chinese patent (publication number 1869119A) discloses the technology of one-step silane method to prepare partially crosslinked high melt strength polypropylene, that is, polypropylene, unsaturated silane and silane alcoholysis agent, organically modified layered silicate, silanol Condensation catalyst, organic peroxide initiator, and grafting aid are pre-mixed, and then fed together into a screw extruder for melt extrusion, so as to achieve grafting and crosslinking of polypropylene and silane in one step. Although this method simplifies The traditional silane method is a complex process, but it is difficult to control the degradation and crosslinking degree of polypropylene

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