Multilayer composite

Details Multilayer composite Multilayer composite

2000-06-29

2002-03-12

Hampton-Hightower, P. (Department: 1711)

Stock material or miscellaneous articles

Composite

Of polyamide

C428S034100, C428S034700, C428S036900, C428S036910, C428S411100, C428S475200, C428S480000, C525S420000, C156S325000, C156S326000, C156S327000, C264S176100, C264S506000, C264S508000, C264S510000, C264S512000

Reexamination Certificate

active

06355358

ABSTRACT:

BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an adhesion promoter for a multilayer composite, and to a multilayer composite which contains this adhesion promoter.
Individual polymers such as polyamides or polyesters are unsuitable for many applications. For example, polyamides are not resistant to weathering since they age upon exposure to the UV radiation from sunlight, extremes of heat and cold, and can absorb atmospheric moisture. This results in discoloration, impairment of the mechanical properties and warping phenomena. In addition, although polyamides have good mechanical properties, particularly good toughness, they provide a poor barrier to the diffusion of molecules: polar substances in particular can easily diffuse through polyamides. Thus, polyamides are unsuitable for use in fuel lines in which alcohol-containing fuel is conveyed, because the alcohol component of the fuel can easily diffuse through the polyamide.
Polyesters generally have good weathering resistance and provide an excellent barrier to the diffusion of both polar and non-polar molecules. However, polyesters are generally impact-sensitive; the notched impact strength of polyesters in particular is frequently inadequate for many applications. Polyesters therefore cannot be used by themselves in many applications in which their other properties, such as their excellent barrier properties, high heat resistance and good rigidity, would be desired.
Similarly, other polymers also exhibit a mix of desirable and undesirable properties such as those described for polyamides and polyesters, and are consequently unsuitable for many applications.
If various polymers could be strongly bonded into laminated articles, it would be possible to combine the complementary properties of various polymers in order to form articles which exhibit some of the best properties of each of the polymer employed. For example, it may be possible to protect polyamide moldings against light and humidity (i.e., weathering) by coating them with a polyester. Similarly, polyester moldings could be weathering) by coating them with a polyester. Similarly, polyester moldings could be protected against chemical and mechanical attack by coating them with a polyamide. Thus, if different polymers could be strongly bonded together, it would be possible to provide articles such as fuel lines, which usually consist of a polyamide (PA), such as PA 6, PA 11 or PA 12 (i.e., poly(&ohgr;-aminocaproic acid), poly(&ohgr;-amino-undecanoic acid), poly(&ohgr;-amino-dodecanoic acid), respectively), with a barrier layer to fuel, in particular to alcohol-containing fuel. In addition, such laminates comprising various layers of different polymers having different functions are more suitable than monolayers for food packaging.
Composites of polyamides and polyesters are already known in principle. EP-A-0 336 806 describes the coextrusion of PA 12 and polybutylene terephthalate (PBT) to give a two-layer pipe. German Patent 38 27 092 describes a multilayer pipe which has, from the inside outward, layers of polyamide, polyvinyl alcohol, polyamide and polyester. However, it is well known that the majority of polymers, including polyamides and polyesters, are incompatible with one another, which is why adhesion is poor between the laminate layers of polymer laminates. However, a strong bond between the individual polymer layers is absolutely necessary in conventional industrial applications.
DE-A 196 33 133 describes a multilayer pipe comprising at least two layers bonded well to one another, where the first layer is a barrier layer and the thermoplastic of the second layer has been treated with polyethyleneimine as adhesion promoter. However, when this process was repeated, the desired bonding did not occur.
A typical approach to bonding, for example polyester and polyamide layers, would be to use an adhesion promoter consisting of a mixture of polyamide and polyester. However, blends of this type, which are usually prepared by mixing the melts in an extruder, are very brittle. Corresponding coextrusion experiments in which the polyamide and polyester are bonded with such polyamide/polyester blend adhesion promoters either exhibit adhesion of the adhesion promoter to the polyamide or to the polyester, but never to both of the two polymers simultaneously.
EP-A-0 509 211 describes thermoplastic multilayer composites in which a layer of a polyamide molding composition and a layer of a polyester molding composition are bonded by means of an adhesion promoter which comprises a mixture of polyamide and polyester. Since the problems discussed above occur here, in a preferred embodiment at least part of the polyamide content and of the polyester content in the adhesion promoter are in the form of a polyamide-polyester block copolymer. However, the preparation of polyamide-polyester block copolymers of this type is not easy and requires the addition of auxiliaries or catalysts. Furthermore, because the block copolymers are prepared by linking suitable end groups of polyamide and/or polyester polymers, precise control of the end groups is necessary in order to ensure that the appropriate end groups are present in sufficient concentration. Since commercial grades of polyamide or polyester polymers do not meet these requirements, specialty grades of these polymers must be prepared and subsequently converted into a block copolymer. The production of adhesion promoters of this type therefore requires considerable effort. This is more particularly true of the block copolyester-amides employed in the process of EP-A-0 837 088 as adhesion promoters in polyamide-polyester multilayer composites.
Composites comprising other materials are also known, but due to the abovementioned incompatibility of most polymer materials, similar types of individually matched adhesion promoters are usually required.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an inexpensive, easy-to-prepare, but nonetheless effective adhesion promoter for a multilayer composite. In a multilayer composite of this type, the layer adhesion should be maintained for a long time, even in contact with reagents such as, for example, fuel, solvents, oil or greases and at elevated temperatures.
This object has been achieved by a thermoplastic multilayer composite comprising at least one layer I of a thermoplastic molding composition, at least one layer II of a further thermoplastic molding composition and, in between layer I and layer II, a layer of an adhesion promoter which comprises at least 5% by weight, preferably at least 10% by weight and particularly preferably at least 20% by weight of a graft copolymer prepared using the following monomers:
a) from 0.5 to 25% by weight, preferably from 1 to 20% by weight and particularly preferably from 1.5 to 16% by weight, based on the graft copolymer, of a polyamine having at least 4, preferably at least 8 and particularly preferably at least 11 nitrogen atoms and having a number average molecular weight M
n
of at least 146 g/mol, preferably of at least 500 g/mol and particularly preferably of at least 800 g/mol, and
b) polyamide-forming monomers selected from lactams, &ohgr;-aminocarboxylic acids and/or equimolar combinations of diamine and dicarboxylic acid.
DETAILED DESCRIPTION OF THE INVENTION
The polyamine component of the graft copolymer can be, for example, the following classes of polyamines:
polyvinylamines (Römpp Chemie Lexikon {Römpp's Lexicon of Chemistry}, 9th Edition, Volume 6, page 4921, Georg Thieme Verlag, Stuttgart, 1992);
polyamines prepared from alternating polyketones (DE-A 196 54 058);
dendrimers, such as, for example, ((H
2
N—(CH
2
)
3
)
2
N—(CH
2
)
3
)
2
—N(CH
2
)
2
—N((CH
2
)
2
—N((CH
2
)
3
—NH
2
)
2
)
2
(DE-A-196 54 179) or tris(2-aminoethyl)amine, N,N-bis(2-aminoethyl)-N′,N′-bis{2-{bis(2-aminoethyl)amino}ethyl}-1,2-ethanediamine or 3,15-bis(2-aminoethyl)-6,12-bis{2-{bis(2-aminoethyl)amino}ethyl}-9-{2-{bis{2-bis(2-

Affiliated with

Also associated with

Rating

Multilayer composite does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Multilayer composite, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Multilayer composite will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2855926