Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a method ~or
permanently bonding shaped parts of soft PVC with shaped parts
of polyolefine polymer by heating.
~ itherto, it has not been possible to bond togethex
shaped parts made of soft PVC with sllaped parts made of polyole-
fines satisfactorily by flame laminating because the melted-on
polyolefine material displays no adllesion to the soft PVC. Even
laminating processes using an adhesive layer result in only sli~ht
adhesive strengths and no permanent adhesion. There are two
essential reasons for this. One is to ~e seen in the poor
adhesion of the adhesives to the polyolefines, the other in the
presence of softeners in the soft PVC, which in the course of
time leads to a softener migration from the PVC into the adhesive
and thus results in a decrease in adhesion.
The adhesion problems encountered in producing a
composite material from a polyethylene foam and a coated or
uncoated synthetic fabric by using heat, have already been
described in German published application D.O.S. 2,261,299.
According to said German D.O.S. 2,261,299, the composite
laminated material is manufactured by coating the synthetic
fabric with a polyur~t~ane resin comprising one or two components,
using temperatures above the melting range of the ~olyethylene
foam material and applying additional pressure to the coated ;
synthetic fabric when bringing the same in contact with the
polyethylene foam. This Icnown method for bonding polyethylene
foam with synthetic fahrics however is not suitable for
permanently bonding shaped parts of soft PVC with shaped parts
of polyolefine polymer, since no adequate softener blocking
action, i.e. no adequate prevention of the migration of the
softener from the soft PVC into the intermediate layer can be
obtained with the polyurethane resins that are used. Furthermore,
the application of pressure is disadvantageous for the foams used
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in the layer structure since it leads -to permanent de~ormations.
The above recited dra~tbacks are also encountered in
the method disclosed in German published application D.O.S.
2,246,750 wherein likewise a pol~urethane foam sheet is used as
adhesion promoter for manufacturing composite ma-terials from foams
consisting of non-cross-linked thermoplastics and other laminar
products, such as textiles, fleeces, etc., by using heat and
pressure.
German published application D.O.S. 2,~35,510, discloses
a method of producing a composite material comprisin~ a layer
of pol~ethylene foam, wherein a polyurethane resin is applied
to the polyethylene foam as adhesion promoter and then the
bonding of the coated polyethylene foam is continued. This
method also fails when a soft PVC shaped part is to be bonded
to the coated polyethylene foam by flame laminating.
The present invention proposes a method of
permanently bonding with good adhesion, i.e. a high separating
resistance, shaped parts made of soft PVC with shaped parts made of
a polyolefine polymer by applying heat without adclitional pressure.
In this regard, the achievement of a good adhesion must he
considered as well as the avoidance of softener migration out
of the shaped part of soft PVC.
The method according to the pres~nt invention
comprises the steps of applying a layer of a cross-linking
synthetic resin made of acrylic resins containing
hydroxyl groups to the surfaces to be bonded of the shaped parts
made of soft PVC and flame-laminating the so-coated parts of soft
PVC o~to tn~ sh~ped parts of polyolefine pnlymer before c~,mp]etion
of the coating synthetic resin cross linking.
Surprisingly, it was found that a coating made of a
cross-linking acrylic resin containing hydroxyl grollps was a
good adhesion promoter with a high adhesive strength as well as
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a softener barrier against sof-tener migration from the PVC.
This method permits to bond shaped parts made of soft
PVC with shaped parts made of polyolefine polymer by flame
laminating a-t an extremely economical cost, that is a-t a very
low cost.
The resistance to separation of the bond obtained
through use of the method according the invention is higher
than the strengths of the ma-terials forming the individual
shaped parts. Therefore, in accordance wi-th the inven-tion, a
bonding of shaped parts of soft PVC with shaped parts of
polyolefine polymer can be obtained in an economical manner,
with small expenditure, wherein the various physical properties
of the materials can be fully used so that even subsequent
deformations of the bond can be made without fear of a later
separation thereof.
The shaped parts to be bonded are preferably in the
form of sheets, foils, plates, capable of being continuously
flame laminated. The use of the invention, however, is not
restricted to these flat laminar structures.
As shaped ~arts made of soft PVC, use can be made
of shaped parts made of soft PVC only or of a copolymer of
solft PVC with vinyl acetate or vinylidenfluoride, in the shape
of foils or foams.
The PVC used in accordance with the invention may
contain additional thermoplastics substances such as acrylic
resins or ethylene or butadiene polymers.
The PVC used in accordance with the invention may
also contain, as additives, suitable amounts of stabilizators,
pigments, extenders, fillers, lubricants, etc
The term "soft PVC" means a PVC bulk mass having a
ratio of PVC to softener comprised between 80/20 and 50/50
by weight, calculated on a total weight of 100. As softeners,
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use can be made of all the known so:Eteners for PVC, such as
phthalate, dioxylphthalate, phosphate softeners, adipates,
etc...
As polyolefine shaped parts, use can be made of foils
or foams of both non-cross-linked and cross-linked polyolefines
selected among all the easy-melted polyolefines, such as
polyethylene, polypropylene or copolymers thereof. Preferably,
use will be made of cross-linked polyethylene foams, such as,
for example, those disclo.sed in U.S. Patent N 3,651,183.
Those polyethylene foams the cross-linking of which ranges
from 70 to 80%, are made of high pressure polyethylene with
a molecular weight of about 40,000 and are manufactured by
using dicumyl peroxide as cross-linking agent and azodicarbona
mide as propellant.
As heat-hardening acrylic resins con-taining hydroxyl
groups use can be made of copolymers of acrylic or methacrylic
acid esters obtained by partial esterification of bifunctional
alcohols such as ethylglycol, diethyglycol or propan-1,3-diol
with acrylic or methacrylic acid . :
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Cross-linking occurs during hea~ hardening. In accordance
with the invention, the cross-]inking of -the acrylic resin~
containing hydroxyl groups is effected in particular by using
isocyanate hardeners.
In accordance wi~h the present invention ,it is essential
that the coating of the synthetic resin is applied to the soft
PVC, for example by injection, pressing, pouring, doctor-knife
coating, spreading or spraying, to obtain a good adhesion
between the selected coating synthetic resin and the soft PVC
and, simultaneously, to avoid migration of the softener, the
applied layer forming a softener barrier having a blocking
effect onto the migration of the softener from the PVC.
If the coating is initially applied onto the polyolefine,
no adequate bond can be obtained with soft PVC.
Bonding of shaped parts made of PVC base and coated
in accordance with the invention, to shaped parts made of
polyolefine polymer can be effected by flame laminating either
immediately or later, but in any case before the end of the
cross-linking reaction of the synthetic resin forming the
coating. The length of time between the application of the
coating and the completion the cross-linking reaction can be
up to one day or more, it all depends on the composition of the
coating synthetic resin used for the coating. The reaction time
of the coating synthetic resin may be from some minutes to a
number of hours. Preferably, the synthetic resin may be from
some minutes to a number of hours. Preferably, the synthetic
resin made of polyacrylates or polymethacrylates containing hydroxyl
groups is used together with an isocyanate hardener. To vary
the reaction time, the coating synthetic resin may have the
following composition: 10 to 100 % by weight of acrylic resin
containing hydroxyl groups; 1 to 50 % by weight of a isocyanate
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hardener; 0 to 90 % by weight of solvents, for example, esters,
ketones, aromatic hydrocarbon or glycoletheracetates; and 0 to
70 ~ by weight of fillers, for example chalk ,siLicates or
pigments.
An essenti~l characteristic of the method according to
the invention lies in the properties of the coating ~hich may
show good to very good adhesion on the soft PVC or the polyolefine
material harden through cross-linking ahility, and react out.
Preferably, as already stated, reactive polyacrylates containing
hydroxyl groups are used as coating.
The flame laminating ~ethod according to the present
invention produces unexpectedly high resistance to separation
between the bonded polyolefine materials and the soft PVC materials,
which is higher than the strengths of the individual materials.
This method is very particularly advantaqeous sincc these high
separating resistances are obtained by flame laminating without
additional contact pressu^e processes or further procedural steps.
Depending on the composition of the coating synthetic
resin for the coating or the method of applying such coating,
for example by pressingj injection, pouring, doctor-knife
coating, spreading, spraying, etc., the degree of wetness o the
coating is more or less great. In accordance to another
prefered embodiment of the invention it is therefore proposed
that the layer of coating synthetic resin be dried beore being
flame laminated. The applied layer of c~ating synthetic resin
is relatively thin and it preferably has a thickness of
approximately 10 to 50~ when wet. ~fter drying, it is correspond-
ingly reduced.
The finished bond between the two shaped parts of
different materials can, if necessary, be subjected to an
annealing process, i.e. a heat treatment, in order to reduce
stresses and disl~cations linked with this.
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The me-thod in accordance with the invenkion is prefer-
ably used for continuously bonding sheets or plates of cross-
linked polye-thylene foam sheets or sof-t PVC foils by flame
laminating. Such composite ma-terials are suitable as heat
insulating or sound insulating or impact-absorbing covering$,
linings, etc.
The method according to invention will be better
understood with reference -to the following non-restrictive
examples and the accompanying drawing, showing a composite
plate obtained in accordance with the present invention, in
cross-section.
Example 1
A coating of synthetic resin was applied onto the ':.
reverse of a chemically expanded PVC foam sheet having a ratio
of PVC to softener, e.g. benzyl butyl phthalate, of 63 : 37, and
fed in roll form in 2 pressing machines, by means of a 48 screen
roller. The synthetic resin consisted of 35% by weight of
acrylic resin containing hydroxyl groups, e.g. PARALOID OL-42*
of the firm Rohm & Haas, USA, or DEGALAN LS 50/100*or DEGLAN
150/300*of the firm Degussa, or MACRYNAL SM500*of the firm
; Hoechst AG, 32% by weight of fillers (chalk, silicates and
pigments), 13% by weight of ~ylol, 12% by weight of ethyl glycol
~: acetate and 8% by weight of isocyanate hardeners (e.g. DESMODUR
(trademark) N, IL) of the firm Bayer AG. In an adjoining
drying channel, the layer of synthetic resin was dried to a
degree of dryness designated as dust dry. The dried layer
had a thickness of about 6 to 7u, whilst previously the applied,
wet layer had a wet thickness of 30u~.
In this regard, it should be noted that it is not
absolutely necessary for the coating to~be dried.
Subsequently the thus coated sheet was run into a
flame laminating device with a flame beam, and was bonded
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directly behind the flame beam with a continuously onflowing
cross-linked polyethylene foam sheet on passing hrough a
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subse~uently disposed pair of rollers forming a roll~r gap of,
for example, 19 ~m. The total material thickness was 20 mm,
and was thereafter deflected to the desired size.
The so obtained composite platcs were stored for one to
two days on flat storage blocks for cooling and hardening.
These plates can, if ncccssary, be subjected ~o an
annealing process to reduce stresses and dislocations.
Subse~uently these plates were edge-trimmed and
packaged.
~xample 2
A coating of synthetic resin having the same composition
as specified in example 1 was applied onto one side of a
commercial soft PVC roof-insulation sheet having a ratio of
PVC to softener of 62 : 38, according to a continuous process in
a pressing maclline, by means of a 48 screen roller. After the
coating was dried, the coated sheet was run into a flame laminat-
ing device and was bonded as in E~ample 1 with a continuously fed
cross-linked polyethylene foam sheet. The bonded sheets were
then rolled on rollers and deflected as desired and kept for
one to two days on storage blocks. They were annealed if
necessary before being packaged.
The so obtained composite materials can be used
e.g. in heat insulating coverings.
The method according the invention is not restricted
only to shaped parts com~risiny one layer of YVC or polyolefine.
It is also possible to bond multi~layer shaped parts, which, in
each case, have one layer of polyolefine or soft PVC and to
obtain strongly adhesive bond of poly~l~fine materials wi-th
soft PVC materials.
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