DE3938552A1 - Crosslinking polyethylene and polyamide by organic peroxide - esp. re-use of composite packaging material - Google Patents

Abstract

Polyethylene and polyamides are cross-linked by radical agents of formula R-O-O-R, esp. 0.001-10% w.r.t. the PE/PA mixt., of 1,3-bis(tert.butyl-peroxyisopropyl) benzene, opt with a co-reagent. R=Ph, aralkoxy, aroyl, alkoxy and/or alkyl. USE/ADVANTAGE- The PE/PA ratio is 50:50-99:1. and the material is a composite packaging film. The process gives a uniform melt, which can be re-processed.

Description

Due to the enormous need for packaging, fall with increasing There is a tendency for ever larger quantities of PE / PA composite films and composite materials which are increasingly being recycled Need to become.

The separation of the products is not without great expenditure on equipment possible and not responsible for the costs. Due to the different physical and rheological properties the products are not uniform even after regranulation Product before, which according to the known methods without problems can be processed further.

A process and co-agents have now been developed with which a homogeneous, chemically bonded PE / PA melt and good processability is given.

Processes and products for peroxidic crosslinking of polyethylene are sufficiently known and described (Plastics Handbook, Volume III Polyolefins).

Peroxidic crosslinking and crosslinking with polyisocyanates polyamides are also known and described (plastics handbook, Volume 6, page 55/56).

Double and triple C bonds are used as coagents containing substances, preferably with triple-C bonds, e.g. B. 2-butyne-1,4-diol

HIGH₂C≡CCH₂OH

wherein the reaction with the NH group of the polyamide is as follows Scheme expires:

where R is the polyamide residue and the resulting double bond for further peroxidic crosslinking with the polyethylene Available.

The amount added, based on the PA content, is 0.5 to 10.0%, with a side effect of a reduction in corrosion Iron is reached.

Further coagents are substances that are functional with isocyanate groups, preferably addition products of diisocyanates with diols, where the diols preferably contain double bonds and an isocyanate group the resulting polydiisocyanate is saturated. There are also addition products with diol adipates and polymers of these products can be used with a functional isocyanate group in the molecule. The isocyanate group reacts with the NH group of the polyamide Formation of urea groups, while the double bonds, the CH₂ group of diphenylmethane diisocyanate and / or the α-CH₂ group the adipic acid for peroxidic crosslinking with the polyethylene is available.

The peroxides and co-agents are the PE-PA mixture, which in Agglomerate or granulate form, or may be present as a regrind and reacted in the melt in the extruder. Preferably, the coagents are added when moving in and the Peroxides are added to the degassing to make the reactions sequential to be able to run out. The peroxides and coagents on the other hand also mixed with the extruded PE / PA mixture, or the Agglomerate or regrind and during processing in the injection molding machine or polymerized in the extruder to the finished product. For setting the melt index and modifying the properties of the PE / PA product, parts of the PE / PA mixture are still 1 to 50% polypropylene added. While networking with PE / PA degradation occurs at the same time with polypropylene, which adjusts the sprayability and other properties can be.

Claims (2)

Polyethylene and polyamide are crosslinked with radical donors of the general formula ROO-R, where R can be phenyl-aralkoxy, aroyl, alkoxy and / or alkyl radical. Crosslinking with 1,3-bis (t-butylperoxyisopropyl) benzene is preferred with or without co-agents. The amounts added range between 0.001 and 10.0% on the amount of PE / PA used, the PE / PA ratio being 50/50 can be up to 99/1.