A laminate comprising a layer of a synthetic linear polyester, a plasticizer-free primer coating applied to at least one surface of the polyester layer and comprising a cross-linked composition comprising a polymer of at least one monomer selected from the esters of acrylic acid and methacrylic acid, and optionally acrylic and/or methacrylic acid, and at least one layer made from a plasticized vinyl chloride polymer composition which is bonded to the linear polyester layer through the intermediary of the primer coating. The primer coating preferably includes the condensation product of an amine with formaldehye to effect cross-linking.

The present invention relates to a laminate and to a method for its 
production. 
It has been found difficult to produce laminates of linear polyesters such 
as polyethylene terephthalate and vinyl chloride polymers since these two 
types of polymers do not usually adhere well to each other; indeed 
polyethylene terephthalate is often used as a release layer for sheets or 
films of vinyl chloride polymers. 
This invention provides a well adhered laminate of a synthetic linear 
polyester and a plasticised vinyl chloride polymer, the effective bonding 
between these two particular polymers being promoted by an intermediary 
primer coating comprising a certain polymeric composition. 
According to the present invention there is provided a laminate comprising 
a layer of a synthetic linear polyester, a plasticiser-free polymeric 
primer coating applied to at least one surface of the polyester layer and 
comprising a cross-linked composition comprising a polymer of at least one 
monomer selected from the esters of acrylic acid and methacrylic acid, and 
at least one layer made from a plasticised vinyl chloride polymer 
composition which is bonded to the linear polyester layer through the 
intermediary of the primer coating. 
According to another apsect of the invention there is provided a process 
for the production of a laminate which comprises applying an aqueous or 
organic dispersion of a polymeric primer composition to at least one 
surface of a layer of a synthetic linear polyester, said primer 
composition comprising a plasticiser-free cross-linkable composition 
comprising a polymer of at least one monomer selected from the esters of 
acrylic acid and methacrylic acid, removing the dispersing medium and 
cross-linking the primer composition, and bonding to one or both sides of 
the polyester layer, through the intermediary of the primer coating so 
formed, a layer made from a plasticised vinyl chloride polymer 
composition. 
According to a further aspect of the invention there is provided the use of 
a plasticiser-free cross-linkable composition, comprising a polymer of at 
least one monomer selected from the esters of acrylic acid and methacrylic 
acid, for the production of a primer coating for a layer of a synthetic 
linear polyester which coating acts, when cross-linked, as an 
adhesion-promoting agent between the layer of polyester and a layer made 
of a plasticised vinyl chloride polymer which is bonded thereto. 
It is to be understood that the term "layer" embraces foils, films and 
sheets. 
The polymer of the primer composition may be a homopolymer or a copolymer. 
The polymer may optionally include a copolymerised component derived from 
acrylic acid and/or methacrylic acid. Preferably the primer composition is 
cross-linked by virtue of the inclusion therein of a condensation product 
of an amine, such as melamine, urea and diazines or their derivatives, 
with formaldehyde, which may be alkylated. 
The above defined primer coating promotes excellent adhesion between the 
linear polyester layer and the plasticised vinyl chloride polymer layer. 
An example of a composition used for the primer coating comprises a 
copolymer of ethyl acrylate, methyl methylacrylate and methacrylamide, 
which has been cross-linked with an ethylated melamine/formaldehyde 
condensation product. The primer composition is preferably cross-linked 
with the aid of a suitable added cross-linking catalyst, e.g. ammonium 
chloride, ammonium nitrate, ammonium thiocyanate, ammonium dihydrogen 
phosphate, ammonium sulphate, diammonium hydrogen phosphate, para toluene 
sulphonic acid, maleic acid stabilised by reaction with a base, or 
morpholinium para toluene sulphonate. The cross-linking is preferably 
effected before the laminating operation begins. The primer coating may be 
applied to the linear polyester layer from an aqueous or organic medium 
but preferably is applied as an aqueous dispersion. The polyester layer 
bearing the dispersion should be dried, preferably by heating to a 
temperature exceeding 70.degree. C. and up to a maximum temperature 
determined by the nature of the polyester employed. Heating not only 
serves to drive off the aqueous or organic medium but also to facilitate 
the cross-linking reactions. 
The primed polyester layer (before lamination) is not at all sticky and can 
be stored (e.g. wound up in a roll) like an unprimed polyester film 
without any problems. 
Examples of suitable synthetic linear polyesters which may be used for the 
laminates of the invention include those polyesters which may be obtained 
by condensing one or more dicarboxylic acids or their lower alkyl 
diesters, e.g. terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 
2,6- and 2,7-naphthalene dicarboxylic acids, succinic acid, sebacic acid, 
adipic acid, azelaic acid, diphenyl dicarboxylic acid, and 
hexahydroterephthalic acid or bis-p-carboxylphenoxy ethane, and optionally 
a monocarboxylic acid, such as pivalic acid, with one or more glycols, 
e.g. ethylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol 
and 1,4-cyclohexanedimethanol. Biaxially oriented and heat-set films or 
sheets of polyethylene terephthalate are particularly preferred for the 
production of laminates according to the invention. 
When the layer of the linear synthetic polyester is an oriented film, e.g. 
a biaxially oriented film of polyethylene terephthalate, the primer 
coating composition may be applied to the polyester layer before or 
between the stretching operations employed to achieve orientation. A 
convenient procedure is to coat the polyester film between the two 
stretching operations which are applied in mutually perpendicular 
directions to orient the film. The heat treatment of the film during the 
stretching operation(s) and heat setting serves also to remove the 
dispersing medium and to effect cross-linking. 
Any suitable vinyl chloride polymer may be employed in the laminates of the 
invention. By a vinyl chloride polymer, is meant a vinyl chloride 
homopolymer or a vinyl chloride copolymer containing at least 50% molar 
(preferably at least 80% molar) of polymerised vinyl chloride. The vinyl 
chloride polymer may be prepared by any suitable polymerisation process, 
e.g. polymerisation in aqueous emulsion, suspension or microsuspension, or 
in bulk, provided the properties (particularly the morphology) of the 
resulting polymer are such that the polymer is siuitable for use in the 
particular lamination procedure envisaged. 
The presence of the plasticiser in the vinyl chloride polymer layer is an 
essential requirement for the achievement of a strong bond. The optimum 
amount or range of plasticiser to be used for any particular laminate 
should be determined experimentally as this depends, inter alia, on the 
minimum acceptable level of adhesion required, on the type of plasticiser 
employed, on the nature of the linear polyester employed, on the nature of 
the vinyl chloride polymer employed and on the method of bonding used to 
form the laminate. However an amount of plasticiser within the range 20% 
to 120% by weight based on the weight of the vinyl chloride polymer is 
usually acceptable for most laminates. Suitable plasticisers for use in 
the laminates of the invention include phthalate esters such as dioctyl 
phthalate, di-iso-octyl phthalate, C7-C9 alkyl phthalate and butyl benzyl 
phthalate, phosphates such as tricresyl phosphate, carboxylic acid esters 
such as di-iso-octyl adipate, di-2-ethylhexyl azelate and dioctyl 
sebacate, compounds derived from soya bean oil such as epoxidised soya 
bean oil, liquid polyester plasticisers such as polypropylene laurate and 
chlorinated substances such as the chlorinated paraffins. The preferred 
plasticisers are the alkyl phthalates, particularly dioctyl phthalate, 
di-iso-octyl phthalate, C7-C9 alkyl phthalate and butyl benzyl phthalate. 
The layer of plasticised vinyl chloride polymer may be incorporated into 
the laminate of the invention by any suitable technique. 
In one method a plastisol or an organosol derived from a vinyl chloride 
polymer (the polymer normally being made by polymerisation in aqueous 
emulsion or microsuspension) is spread onto a primed layer of a linear 
polyester and the assembly is heated to gel the plastisol or (after 
removal of the diluent) the organosol into a coherent layer. The heating 
may also cause the vinyl chloride polymer layer to become acceptably 
bonded to the linear polyester layer. If the adhesion is insufficient, 
further heating and/or pressure may be applied to effect a strong bond. 
Alternatively the plastisol may be embossed. The plastisol in some cases 
may advantageously be foamable, so that the plastisol fusing step also 
causes a foamed vinyl chloride polymer layer to be formed. 
In another method, a pre-formed plasticised film containing a plasticised 
vinyl chloride polymer (the polymer normally being made by polymerisation 
in aqueous suspension, microsuspension or emulsion) and a primed film of a 
linear polyester (usually polyethylene terephthalate) are fed through hot 
rollers (provided e.g. by a calender) in order to bond the polyester film 
to the plasticised vinyl chloride polymer film. 
The laminates of the invention find uses in many applications. For example 
they may form the basis of laminated cushioned flooring, the cushioned 
flooring comprising e.g. a support polyethylene terephthalate film 
laminated on its lower side, through the intermediary of a primer coating 
(as defined), to a filled unfoamed plasticised vinyl chloride polymer 
layer forming the base of the flooring (the filler e.g. being a heat 
stabilised TiO.sub.2 composition), and on its upper side, again through 
the intermediary of a primer coating (as defined) to a foamed layer of a 
plasticised vinyl chloride polymer which has been applied by spreading a 
plastisol as described above, the upper surface of the foam being suitably 
patterned (e.g. by printing) and normally protected by a clear 
wear-resistant layer. 
The laminates of the invention may also be used as the basis of solid (i.e. 
entirely unfoamed) floor or wall tiles which comprise e.g. a filled 
plasticised vinyl chloride base layer suitably patterned on its upper 
surface (e.g. by printing) and laminated, through the intermediary of a 
primer coating (as defined), to a clear wear-resistant layer of 
polyethylene terephthalate, the lamination being effected by calendering 
the vinyl chloride layer (pre-formed) and the primed polyethylene 
terephthalate layer. 
Another use for laminates of the invention is as protective, tamper-proof 
coverings for identification cards such as security cards, bank cards, 
credit cards, identity cards and the like. These can be prepared by 
covering the card on each surface with facing polyester/vinyl chloride 
polymer laminates according to the invention the layers being in the form 
of flexible or stiff films) each laminate extending beyond the card 
perimeter and the linear polyester layers of the laminates being outermost 
and the plasticised vinyl chloride polymer layers being innermost; the 
assembly can then be heat-sealed e.g. by passing it through hot rollers, 
the innermost plasticised vinyl chloride polymer layers enabling each 
laminate to be bonded to the card and also to the part of the opposite 
laminate which is beyond the perimeter of the card. 
Another possible application for laminates according to the invention is 
their use as cladding for various substrates, e.g. GRP sheet, where the 
linear polyester layer improves the ageing performance of the substrate 
while the vinyl chloride polymer layer (situated outermost) decreases the 
susceptibility of the polyester to degradation by ultra-violet light. 
Another use for laminates according to the invention is as adhesive tapes 
in packaging and electrical applications where the laminated tapes replace 
those made solely from vinyl chloride polymers which are known to suffer 
from poor transverse tensile strength. The polyester layer (when biaxially 
oriented) significantly improves the transverse tensile strength of the 
tape while the plasticised vinyl chloride layer enables a very thin 
polyester layer (e.g..about.10-15.mu.) to be employed without detracting 
from the tape's improved tensile properties; a thick polyester tape would 
be economically less attractive. The plasticised vinyl chloride polymer 
layer should also be very thin (e.g..about.12-18.mu.) in order for the 
total tape thickness to be acceptably thin, and so the lamination is 
preferably effected by the application of an organosol of the vinyl 
chloride polymer to the primed polyester film and (after removing the 
volatile diluent) gelling the organosol.

The laminate of FIG. 1 has a plasticised film 1 of a vinyl chloride polymer 
bonded, through the intermediary of a primer coating 2 according to the 
invention, to a biaxially oriented film 3 of polyethylene terephthalate. 
The laminate of FIG. 2 consists of a foamed plasticised layer 4 of a vinyl 
chloride polymer bonded, through the intermediary of a primer coating 5 
according to the invention, to a biaxially oriented film 6 of polyethylene 
terephthalate. 
The solid floor or wall tile of FIG. 3 consists of a base sheet 7 of a 
filled plasticised vinyl chloride polymer bonded through the intermediary 
of a primer coating 8 according to the invention to a wear-resistant 
biaxially oriented film 9 of polyethylene terephthalate. The sheet 7 has a 
printed pattern, denoted by 10, on its upper side. 
The cushioned flooring of FIG. 4 consists of a biaxially oriented film 11 
of polyethylene terephthalate primed on each side with primer coatings 12 
and 13 and bonded through the intermediary of the primer coatings 
respectively to a base sheet 14 made from a filled plasticised vinyl 
chloride polymer and to a foamed layer 15 made from a plasticised vinyl 
chloride polymer. The foamed layer 15 has a printed pattern, denoted by 
16, on its upper side which is protected by a wear-resistant layer 17. 
The present invention is further illustrated by the following Examples. 
Unless otherwise specified, all parts and percentages are by weight. 
EXAMPLE 1 
A biaxially oriented film of polyethylene terephthalate was prepared by 
stretching in mutually perpendicular directions at 90.degree.-95.degree. 
C. followed by heat-setting at about 210.degree. C.; after the first 
stretching operation the film was coated on one side with a primer 
composition derived from an aqueous latex of 9.6 parts of a cross-linkable 
acrylic composition consisting of 87% of a copolymer of ethyl acrylate, 
methyl methacrylate and methacrylamide (45%, 50% and 5%) and 13% of 
ethylated melamine formaldehyde, 0.3 parts of poly(ethylene oxidepropylene 
oxide) emulsifier, 0.1 parts ammonium chloride (catalyst) in 90 parts 
water, the heating during the second stretching operation and heat setting 
serving to remove the water and cross-link the acrylic composition. The 
film was coated on the primed side with a plastisol composition having the 
following formulation: 
Vinyl chloride homopolymer (K65) (prepared by microsuspension 
polymerisation): 100 parts 
Di-iso-octyl phthalate: 80 parts 
Ground limestone (filler): 100 parts 
Ba/Cd based liquid (stabiliser) 2 parts 
The plastisol was produced by mixing the constituents in a planetary mixer 
and was spread as a 3 mm thick layer on the coated polyethylene 
terephthalate film using knife-over-roll coating. The coated assembly was 
passed through a circulating air oven at 190.degree. C. for 3 minutes to 
fuse the plastisol and to generate a bond between the vinyl chloride 
homopolymer and the polyethylene terephthalate film. The laminate was 
cooled and reeled. 
The bond between the vinyl chloride homopolymer film and the polyethylene 
terephthalate film was found to be very strong. The type of laminate 
formed is illustrated in FIG. 1. 
EXAMPLE 2 
The procedure used was substantially that of Example 1. However the vinyl 
chloride homopolymer plastisol employed was foamable and had the following 
formulation: 
Vinyl chloride homopolymer (K65) (prepared by microsuspension 
polymerisation): 100 parts 
Butyl benzyl phthalate: 30 parts 
C7-C9 alkyl phthalate: 20 parts 
Chlorinated paraffin wax: 12 parts 
Azodicarbonamide (blowing agent): 2 parts 
Dibasic lead phosphate (stabiliser): 3 parts 
TiO.sub.2 (pigment): 5 parts 
The assembly (having an unfoamed plastisol layer 1 mm thick) was heated at 
195.degree. C. for 3.5 minutes, producing a foamed vinyl chloride polymer 
layer 3.5 mm thick bonded strongly to the polyethylene terephthalate film. 
The type of laminate formed is illustrated in FIG. 2. 
EXAMPLE 3 
The coated polyethylene terephthalate film as used in Examples 1 and 2 was 
used for this Example. A calendered vinyl chloride copolymer sheet having 
the following formulation was prepared: 
Vinyl chloride/vinyl acetate (85/15) copolymer (prepared by suspension 
polymerisation): 100 parts 
Dioctyl phthalate: 35 parts 
Calcium carbonate (filler): 360 parts 
Asbestos powder (filler): 90 parts 
Heat stabiliser: 3 parts 
This calendered sheet was press laminated (160.degree. C., 4 minutes 
pressing) to the primed polyethylene terephthalate film. The bond formed 
was very strong. 
The type of laminate formed is illustrated in FIG. 1 (with the vinyl 
chloride layer being made from a calendered sheet and not from a plastisol 
as in Example 1). 
EXAMPLE 4 
Cushion flooring of the type illustrated in FIG. 4 was prepared, starting 
from biaxially oriented polyethylene terephthalate film coated on both 
sides with the primer composition used in Examples 1 to 3. 
Firstly, a layer of filled unfoamed vinyl chloride polymer (e.g. made from 
the formulation used in Example 1 or Example 3) was bonded to the 
polyester layer using any suitable technique (plastisol spreading, 
calendering, pressing) so as to form the base of the flooring. Next, a 
foamable plastisol derived from a vinyl chloride polymer (having the 
formulation of the plastisol composition used in Example 2) was spread 
onto the upper side of the primed polyester layer and foamed and gelled by 
heating. The cushion flooring was suitably patterned by printing and 
finished with a wear-resistant layer.