GB2338241A

GB2338241A - Chlorinated polyolefin adhesive compositions

Info

Publication number: GB2338241A
Application number: GB9912945A
Authority: GB
Inventors: Alan Gray; Anthony Keith Powell; Paul Robert Rostron
Original assignee: BP Chemicals Ltd
Current assignee: BP Chemicals Ltd
Priority date: 1998-06-11
Filing date: 1999-06-03
Publication date: 1999-12-15
Also published as: GB9912945D0; GB9812640D0

Abstract

Chlorinated polyolefin adhesive compositions for bonding linear alternating polyketones to polyolefins.

Description

2338241 Case 8968(2) CELORINATED POLYOLEFIN ADIHESIVE COMPOSITIONS The

present invention relates to adhesive compositions and multi-layered structures comprising the adhesive compositions, in particular, multilayered structures comprising at least one layer of a polyketone composition.

For the purposes of this patent, polyketones are defined as linear polymers having an alternating structure of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds. Although for the purposes of this patent polyketones correspond to this idealised structure, it is envisaged that materials corresponding to this structure in the main but containing small regimes (i.e. up to 1 Owt%) of the corresponding homopolymer or copolymer derived from the olefinically unsaturated compound, also fall within the definition.

Such polyketones have the formula: 0 [(CR2-CR2)C1m (1) where the R groups are independently hydrogen or hydrocarbyl groups, and m is a large integer; they are disclosed in several patents e.g. US 3694412. Processes for preparing the polyketones are disclosed in US 3694412 and also in EP 181014 and EP 121965.

Polyolefin-containing blends suitable for use as adhesive layers in multilayered structures are known. These adhesive blends are commonly referred to as tie-layers. For example, US Patent 2081723 discloses a modified polyolefin adhesive blend comprising (A) a graft copolymer of a polyethylene back-bone grafted with at least one polymerisable ethylenically unsaturated carboxylic acid or carboxylic acid anhydride and (B) a blending resin mixture comprising a linear low density polyethylene and 1 \.--. 1 polypropylene. The patent states that the adhesive blends can be used to join polypropylene to a number of polar materials or to join two polar materials together.

WO 9509212 relates to a polyolefin-containing adhesive blend suitable for bonding polyolefins, in particular, polyethylene or polypropylene to polyketones which 5 blend has good adhesion to polyolefins while maintaining good adhesion to the polyketone. The polyolefin-containing adhesive blend is said to comprise: (A) 1 to 30 parts by weight of a graft copolymer having a polyolefin backbone grafted with 0.001 to 30% by weight of at least one polymerisable ethylenically unsaturated carboxylic acid or derivative thereof, (B) 70 to 99 parts by weight of a polyolefin provided that at least 5 parts by weight of (B) is (C) a polyolefin having a density of less than 930kgm wherein the graft copolymer (A) has been reacted with a compound (D) which has at least two primary or secondary amino groups at least one of which is a primary amino group, the sum of (A), (B) and (C) being 100 parts by weight.

There remains the need for further adhesive compositions which have good adhesion to both polyolefins and polyketones.

Thus, according to the present invention there is provided an adhesive composition comprising a chlorinated polyolefin.

The chlorinated polyolefin can be a chlorinated homopolymer of an olefin e.g. ethylene or propylene, in particular a chlorinated high density polyethylene (Cl-HDPE), a chlorinated low density polyethylene (Cl-LDPE), a chlorinated linear low density polyethylene (Cl-LLDPE) or a chlorinated very low density polyethylene (Cl-VMPE), preferably Cl-LLDPE, or a chlorinated copolymer of an olefin e.g. propylene with ethylene, butene or other unsaturated aliphatic hydrocarbons or a chlorinated terpolymer of an olefin e.g. ethylene with propylene and a diene. Blends of two or more chlorinated polyolefins can be used.

Where the adhesive composition of the present invention is used tobond a polyolefin to a polyketone it is preferred that the chlorinated polyolefin is selected such that the polyolefin which is chlorinated is the same as the polyolefin to which the polyketone is to be bonded. Alternatively, the adhesive composition may comprise a blend of a chlorinated polyethylene and the polyolefin to which the polyketone is to be 2 1 bonded.

Where the adhesive composition comprises a blend of a chlorinated polyethylene and the polyolefin to which the polyketone is to be bonded, it is preferred that the chlorinated polyethylene comprises 1 to 99, more preferably 1 to 90, most preferably 1 to 50, for example, 5 to 20% by weight of the adhesive composition.

The adhesive composition of the present invention may further comprise a polyketone (i.e. a blend of a chlorinated polyolefin and a polyketone). Where the adhesive composition is used to bond a polyolefin to a polyketone it is preferred that the optional polyketone is the same as the polyketone to which the polyolefin is bonded.

The adhesive composition may comprise a blend of a chlorinated polyethylene, the polyolefin to which the polyketone is to be bonded and the polyketone which is to be bonded.

Where the adhesive composition comprises a blend of a chlorinated polyolefin and a polyketone, it is preferred that the chlorinated polyolefin comprises 1 to 99, more preferably 1 to 90, most preferably 1 to 50, for example, 5 to 20% by weight of the adhesive composition.

Methods for preparing chlorinated polyolefins are well known and any suitable method can be used to prepare the chlorinated polyolefin. One such suitable method comprises treating the polyolefin, for example a polyethylene, with chlorine. The chlorination reaction proceeds via a free-radical mechanism, usually catalysed by ultraviolet fight or initiators. Thus, a chlorine radical abstracts a hydrogen atom from the polymer chain leaving a carbon radical which reacts with a molecule of chlorine to attach one chlorine atom to the polymer chain and liberate the other to continue the chain reaction.

The chlorinated polyolefin may contain 5 to 50% by weight chlorine, preferably 20 to 50 %, more preferably 23 to 48%, most preferably 25 to 40% by weight chlorine.

Optionally, a polyolefin is added to the adhesive composition of the present invention to modify the rheological, viscoelastic or adhesive properties of the composition ('modifying polyolefin"). Any suitable polyolefin can be used e.g.

polyethylene, polypropylene, copolymers of ethylene or copolymers of propylene with one or more comonomers e.g. butene, vinyl acetate, ethyl acrylate and methyl acrylate.

3 ill 1 1 -1 Suitably, the polyolefin may be a very low density polyethylene (VLDPE), linear low density polyethylene (LLDPE) or ethylene propylene rubbers. A mixture of two or more polyolefins can be added to the adhesive composition of the present invention, preferably two polyolefins.

Where a "modifying polyolefin" is added to the adhesive composition of the present invention, the "modifying polyolefin' is present in amounts of from 1 to 50% by weight, preferably 1 to 30% by weight based on the total amount of the composition.

The chlorinated polyolefin and the optional "modifying polyolefie' or the chlorinated polyethylene, the polyolefin to which the polyketone is to be bonded and the 10 optional "modifying polyolefin" can be blended using known techniques and equipment for batch or continuous blending.

The adhesive composition according to the present invention may also contain conventional additives such as, for example, antioxidants, stabilisers, and mould release agents.

is The adhesive composition according to the present invention is particularly suitable for bonding polyolefins to polyketones. Methods for using adhesive compositions to bond polyolefins to polar substrates are known and include lamination, coextrusion, extrusion lamination and coextrusion coating.

The present invention includes multi-layered structures comprising a first layer comprising a polyolefin composition and a second layer comprising a polyketone cornposition,. the first and second layers being bonded together with an intermediate layer of an adhesive composition according to the present invention. In particular, the present invention relates to such multi-layered structures when prepared by co-extrusion e.g. multilayered film produced by co-extrusion. The polyolefin composition of the first layer may comprise a polyolefin, blends of polyolefins or blends of a polyolefin and a polymer other than a polyolefin (for example, a blend of a polyolefin and a polyamide). Preferably, the polyolefin composition of the first layer comprises a major proportion of an olefin homopolymer, copolymer or terpolymer. The polyolefin composition of the first layer may comprise a recycled polyolefin or a mixture of recycled and virgin polyolefin. The polymer composition of the first layer may contain conventional fillers. The second layer comprises a polyketone composition. As noted above for the purposes of this patent, polyketones are defined as linear polymers having an alternative structure 4 of (a) units derived from carbon monoxide and (b) units derived from one or more olefinically unsaturated compounds. Suitable olefinic units are those derived fromC2 to C12alpha-olefins or substituted derivatives thereof or styrene or alkyl substituted derivatives of styrene. It is preferred that such olefin or olefins are selected from C2 to C6normal alpha-olefins (i.e. straight chain alpha-olefins) and it is particularly preferred that the olefin units are either derived from ethylene or most preferred of all from a mixture of ethylene and one or moreC3 to C6normal alpha-olefin(s) especially propylene. In these most preferable materials it is further preferred that the molar ratio of ethylene units toC3 to C6normal alpha-olefin units is greater than or equal to 1 most preferably between 2 and 30.

The multi-layered structures according to the present invention can include further layers in addition to the three layers hereinbefore defined- For example, a fivelayered structure can comprise a first layer of a polyolefin composition, a second layer of an adhesive composition according to the present invention, a third layer of a polyketone composition, a fourth layer of an adhesive composition according to the present invention and a fifth layer of a polyolefin composition.

The present invention includes articles produced by thermoforming a multilayered film or sheet comprising a first layer comprising a polymer composition e.g. a polyolefin composition and a second layer comprising a polyketone composition, the first layer and the second layer being bonded together by an intermediate layer of an adhesive composition according to the present invention.

The invention is illustrated by the following example:

Materials Polyketone (PK): Melting point 203'C, melt flow rate) 80 g/10 minutes (250'C, 5 kg load); Polyethylene (PE): LL 0220 AA supplied by BP Chemicals Lirnited.

Chlorinated polyethylene (CPE): TYRIN CM 674 supplied by Du Pont Dow Elastomers which contains 23-27% by weight chlorine.

Chlorinated polyethylene (CPE): Tyrin BH 9000 supplied by Du Pont Dow Elastomers which contains 40% by weight chlorine. Detern-dnation of Melt Flow Rate The melt flow rate) of the polyketone (PK) was measured using a 1 Davenport Melt Index Tester. Tests were carried out at a temperature of 250C and an applied load of 5 kg. The N1FR was calculated from the mass of extrudate pushed through a die (2.095 mm diameter) over a 30 second period on application of the load 4 minutes after charging the polymer into the barrel of the instrument at a temperature of 250'C. Otherwise, standard procedures were followed (e.g. ISO 1133).

ExaWle Compression moulded sheets (150 pLm) of the chlorinated polyethylene polymers (CPE) were produced using a 20 tonne Moore press under the following conditions: a 15 x 15 cm x 130 pLm "picture ftame" mould was preheated for 5 minutes at 20WC, pressed at 15 tonnes for 5 minutes and crash cooled to room temperature.

Polyketone (PK) and polyethylene (PE) sheets were made using a similar procedure to that given above.

Multilayer structures of P&CPE/PE were prepared via the following procedure:

three individual sheets (PK/CPEIPE) were placed within a 15 x 15 cm x 3 90 PLm picture frame mould. This was preheated at 22CC for 30 seconds, pressed at 10 tonnes for 10 seconds and then crash cooled to room temperature. The resultant multilayer structure was then cut into 2.5 cm wide strips and the level of adhesion between each layer was assessed using a standard T-peel test (in accordance with BS 5350).

The chlorinated polyethylene (CPE) layer could not be peeled from either the polyketone (PK) or polyethylene (PE) sheets of the multilayer structure.

6 Case 8968(2)

Claims

Claim:

1. An adhesive composition comprising a chlorinated polyolefin.

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