Multi-layer thermoplastic composites

Details Multi-layer thermoplastic composites Multi-layer thermoplastic composites

1998-12-22

2001-09-04

Kiliman, Leszek (Department: 1773)

Stock material or miscellaneous articles

Hollow or container type article

Polymer or resin containing

C428S036910, C428S476300, C428S477400, C428S524000

Reexamination Certificate

active

06284334

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to multi-layer thermoplastic composites.
Polyamides (hereinafter abbreviated to PA) generally have good mechanical properties, in particular high strength, but also exhibit a poor barrier effect; thus polar substances can easily migrate through polyamides. This constitutes a major problem for fuel lines, for example, in which alcohol-containing felt is transported.
Ketone resins are formed from alkaline-catysed self condensation of ketones cyclohexanone, methylcyclohexanone), or from co-condensation of ketones (acetone, butanone, acetophenone, cyclohexanone, methylcyclohexanone) with formaldehyde-producing, nonsaponifiable and neutral reacting resins (synthetic resins) of light colour and softening ranges of 80-130 C. Co-condensates of ketones (e.g., cyclohexanone) with long chain aldehydes are of no technical significance. The ketones can be divided into acetone, acetophenone resins, etc., depending ion the starting ketone. Ketones from mixtures of different ketones are also known.
Polyketone polymers (hereinafter abbreviated to PK) are known in the art. As an example, United States patent U.S. Pat. No. 4,880,903 describes linear alternating polyketone terpolymers based on carbon monoxide, ethylene and other olefmically unsaturated hydrocarbons such as propylene.
U.S. Pat. No. 4,843,144 describes a process for the production of linear alternating polyketone-polymers from carbon monoxide and at least one ethylenically unsaturated hydrocarbon, employing palladium catalysts.
Other aliphatic polyketones based on ethylene, carbon monoxide and propylene have been described, for example in European patents EP-A-0,457,374 and EP-A-0,569,101, and are sold under a variety of trade names.
U.S. Pat. No. 5,232,786 describes multi-layer structures containing aliphatic polyketones and polyamides. The individual layers are, however, only mechanically bonded and characterized in that the individual layers can easily be separated by hand. In practice, in particular when used in car manufacturing in which hoses and pipes are constantly in contact with fuiels, a permanent bond which cannot be separated by external influences is required. U.S. Pat. No. 5,232,786 describes a terpolymer based on PA6, PA66 and PA12, which inseparably bonds to the polyketone. Copolymers, however, have the disadvantage of having low melting points, low crystallinity and poor crystallisability, which results in reduced resistance to gasoline and slow processing.
EP-A-0,569,101 describes multi-layer systems of polyketone polymers (PK) and polyamides (PA) which contain polymerised-in units of hexamethylenediamine and adipic acid. However, the layers in pipes manufactured from the two materials can be separated by hand. Such bond strengths are not suitable when making pipes and hoses specifically for transporting fuel. The swelling stress caused by contact with gasoline then leads to delamination of the layers.
Composite materials from polyamide and polyketone polymers with adhesively bonded layers are not so far known. The prior art only indicates the use of binding agents or compatibilising layers between layers of polyamides and polyketone which produce an adhesive bond. An adhesively bonded thermoplastic multi layer composite is vital for technical use, for example in automobile hoses.
The aim of the invention is thus to provide thermoplastic multi-layer composites in which for the first time, a polyamide layer is adhesively bonded to a polyketone layer.
SUMMARY OF THE INVENTION
The present invention includes a thermoplastic multi-layer composite having a first layer that includes a first moulding compound and a second layer that includes a second moulding compound, with at least part of the second layer located adjacent and adhesively bonded to at least part of the first layer. In the thermoplastic multi-layer composite, the first moulding compound is based on a polyamide that has a ratio of amino to carboxyl end groups greater than 1, and, the second moulding compound is based on a linear alternating polyketone that is based on carbon monoxide and an ethylenically unsaturated hydrocarbon compound. The present invention further includes a use of the thermoplastic multi-layer composite.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention provides a thermoplastics multi-layer composite according to claim
1
, which comprises at least a layer a) formed from a moulding compound based on a polyamide and b) a second layer formed from a moulding compound based on a linear alternating polyketone polymer from carbon monoxide and an ethylenically unsaturated hydrocarbon compound which is adjacent at least in part to layer a). The special polyamide of the invention, which has a ratio of amino to carboxyl groups of more than 1, for the first time enables polyamides to be adhered to polyketone layers without bonding agent layers therebetween.
The dependent claims define advantageous embodiments of the invention.
The multi-layer composite can also be in the form of a hose or pipe line (claim
13
). In this case, the PK layer forms the inner layer. At least one PA layer is adjacent it. Aliphatic mono- and co-polymers can be used for the polyamides in layer a). Examples are PA6, PA66, PA612, PA8, PA88, PA9, PA11, PA12, PA1212, PA1012, PA1112 and the like The polyamide reference is in accordance with international standards, in which the first number(s) represents the number of carbon atoms of the starting diamine and the last number(s) represent the number of carbon atoms in the dibasic carboxylic acid. If only one number is given, this means that the starting material is the a, (o-aminocarboxylic acid or the lactam derived therefrom.
When copolymers are used, these can contain adipic acid, sebacic acid, suberic acid, isophthalic acid, or terephthalic acid as co-acids, or (4′-aminocyclohexyl) methane, trimethylhexamethylenediamine, hexamethylenediamine or the like as the co-diamine.
The preparation of this co-polyamide is described, for example, in German patent DE-A-2 152 194.
Mixed aliphatic/aromatic polycondensates, such as those described in U.S. Pat. No. 2,071,250, U.S. Pat. No. 2,071,251 etc., are also suitable polyamides. Poly(etheresteramide)s and poly(etheramide)s are also suitable polycondensates for the polyamide. Products of this type are described in DE-A-2,712,987, for example.
If necessary, the polyamides can be impact resistant. Examples of suitable modifiers are ethylene/propylene or ethylene/propylene-diene-copolymers or impact resistance producing rubbers.
The polyketone contained in the multi-layer composite of the invention has the following general formula I:
—[CO(—CH2-CH2)]
x
[CO—(—G—)—]
y
where G is derived from an &agr;-olefm monomer containing at least 3 carbon atoms, bonded together with at least one or more ethylenically unsaturated compounds, x and y are whole numbers, and the ratio of y to x is no more than 0.5.
In particular, polymer G; in formula I is propylene and the ratio of y to x is in the range 0.01 to 0.1.
The polyketone of the invention is characterized in that it is an alternating copolymer of ethylene and carbon monoxide, into which a firther olefin such as propylene or butylene can be polymerised.
Polyketone polymers with a melting point of 175° C. to 300° C., in particular 210° C. to 270° C., are inserted into the multi-layer composite of the invention. The polymers typically have a limiting viscosity number (LVN), determined in m-cresol at 60° C., of 0.5 dl/g to 10 dl/g, preferably 0.8 dl/g to 4 dl/g.
Polyketone polymers are known from U.S. Pat. No. 4,880,903 and from U.S. Pat. No. 4,843,144.
In addition to layers a) and b) of the invention, the thermoplastic multi-layer composite can include a further layer c). This layer is adjacent layer a) and arranged opposite layer b). Layer c) is also adhesively bonded to layer a). A chemical reaction apparently occurs between the polyamide of the invention with excess amino end groups and the polyketone polymer in the boundary layer. If a polyamide wit

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