Preparation method of polypropylene foaming sheet material

Abstract

The invention provides a preparation method of a polypropylene foaming sheet material. Homo-polypropylene as base resin and ammonium polyphosphate as a fire retardant undergo foaming in the presence of a supercutical fluid foaming agent so that the polypropylene foaming sheet material is prepared. The preparation method comprises that two or more stages of propylene homopolymerization reactions occur in two or more reactors connected in series, wherein external electron donors used in the two or more stages of reactions respectively are silane and diether compounds. The halogen-free flame-retardation polypropylene foaming sheet material obtained by the preparation method has the advantages of low production cost, short production period, compact foam apertures, uniform aperture distribution and high burning oxygen index and can be used in occasions of automobile parts, steamships and aircraft weight reduction assemblies, and electronic packaging and building decoration having high flame-retardation requirements.

Description

technical field [0001] The invention relates to the field of macromolecules, in particular to a method for preparing a halogen-free flame-retardant polypropylene foam board. Background technique [0002] Polymer foam is composed of extremely small air cells and a thin air cell film that surrounds the air cells. Due to the high volume ratio of gas, good heat insulation, cushioning, and floating properties, and high cost performance, it can be used in a wide range of fields. In recent years, polypropylene resin foam has been widely used in thermal insulation building materials, automotive components, packaging cushioning materials and other fields due to its good performance and cost balance, and can be recycled. For example, as a thermal insulation building material, polypropylene resin foamed boards are used in building floors or inside walls, showing good thermal insulation performance, and are widely recognized and used in the market. [0003] The methods for preparing po...

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Problems solved by technology

However, this method is produced in batches, the manufacturing process is complicated, the energy consumption is high, and continuous production cannot be performed, so it has the characteristics of high manufacturing cost.

The latter is to put polypropylene composition particles into the extruder, use carbon dioxide, hydrocarbons, chemical blowing agents or crosslinking agents as needed, melt and knead under heat and pressure, and extrude foaming, but use carbon dioxide The foamed sheet obtained by using a foaming agent has a high opening rate and poor mechanical properties; the foamed sheet obtained by using a chemical foaming agent has a low foaming ratio, no obvious weight loss, and narrow application fields

For example, a cross-linked polyolefin resin foam is introduced in Chinese patent CN200680017108.5. Although the foam has good heat resistance, the polypropylene foam cannot Recycling is easy to cause environmental pollution

Chinese patent CN200510057317.X introduces a method for manufacturing polypropylene foam sheets, but this method uses chemical foaming agents such as AC foaming agents, and the expansion ratio is low, so it is not suitable for foaming materials that require high weight loss field

Chinese patent 201210298715.0 introduces a manufacturing method of a halogen-free flame-retardant polypropylene foam. The foam uses a halogen-free phosphorus flame retardant, but the foaming process requires irradiation cross-linking, which also makes the product unrecyclable.

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