Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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me present invention relates to flame resistant l a ates comprising
a length of sheeting, in particular a textile sheeting, and a polyurethane foam
bonded thereto, said foam having been rendered flame resistant by treatment witha mixture of an elastQmer latex and a flame retarding additive followed by cross-
linking of the latex, to a prooe ss for the manufacture of such laminates and totheir use for covering combustible upholstery materials.
It is already kncwn frQm British Patent No. 977,929 to reduce the
flammability of foams by treatment with vulcanizable elastomer latices in which
vulcanization is carried out in the usual manner with sulphur, with the additionof knGwn sulphur-containing vulcanization accelerators.
In the process according to German Offenlegungsschrift No. 2,649,222,
inorganic flame retarding additives such as magnesium carbonate or alumLnium
hydroxide are intrcduced into a foam in order to render it more flame resistant
by means of elastomer latices, and the latices are subsequently cross-linked with
sul~hur.
In German Auslegeschrift No. 2,618,216 and in German Offenlegungsschrift
No. 2,659,886 it is proposed to reduce the combustibility of upholstery by cover-
ing it with a polychloroprene foam containing a hydrated inorganic compound and
cptionally a substance which promotes cæbonization.
It has now been found that laminates comprising a polyurethane foam
which has been rendered flame resistant and a length of sheeting, preferably a
textile sheeting, onded thereto æe flame resistant or self-extin B shing and
eminently suitable for use as fire protection materials, e.g. for covering com-
bustible upholstery.
me present invention provides a flame resistant
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laminate comprising
a) A textile sheeting in the form of a woven or kn;tted fabric
or non-woven bonded web of natural and/or synthetic fibres.
b) A polyurethane foam bonded to at least one side thereof,
said foam being a polyether or polyester foam which has
been rendered flame resistant by treatment with a mixture
of polychloroprene latex containing carboxyl groups and
aluminium hydroxide followed by cross-linking of the latex
with zinc oxide or magnesium oxide.
The present invention also provides a process for the preparation
of a flame resistant laminate which comprises (i) bonding a textile in the
form of a woven or knitted fabric or non-woven bonded web of natural and/or
synthetic fibres to a polyurethane foam which is a polyester or polyether
urethane foam by gluing, flame laminating or direct foaming, (ii) treating
the foam with a mixture of a chloroprene latex containing carboxyl groups and
aluminum hydroxide and (iii) subsequently cross-linking the latex with zinc
oxide or magnesium oxide.
The present invention also provides a process for the manufacture
of flame resistant upholstery materials by partial or complete covering or
enveloping of combustible upholstery materials with the flame resistant
laminates of the present invention.
The laminates of the present invention may be constructed of a
single layer, for example by the application of only one layer of polyurethane
foam to the length of sheeting. Multi-layered laminates may be obtained,
for example by bonding a layer of polyurethane foam to each side of the length
of sheeting. The thickness of the laminates is generally from 2 to 50 mm and is
preferably fronl 5 to 30 mm. As a textile sheeting in the form of a woven or
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knitted fabric or non-woven web of natural and/or synthetic fibres, a cotton
weave optionally pretreated with a flame retarding additive is particularly
preferred.
The polyester or polyether urethane foams used in the construction
of the laminates of the present invention may be any of the so-called flexible
polyurethane foams which are mainly open celled
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or reticulated. Polyurethane foams having a unit weight of 10 to 50 kg/m3
are preferred.
The bond between the sheeting and the polyurethane foam may be produced
in known manner, e.g. by gluing or by flame laminating, or by direct foaming
preferably, however, the bond is produced by flame laminatingor by direct
foaming. The sheeting used may have a solid surface or else it may be per-
forated, for example with slits or holes, but combinations of these types
of sheeting may also be used.
The substance used for treating the polyurethane foam is polychloro-
prene in the form of the latex, generally having a solids content of from 30 to
70% by weight, preferably of from 40 to 60% by weight. Latex containing small
quantities of the usual additives such as methyl cellulose may also be used.
The polychloroprene used in the present invention contains carboxyl groups
and are capable of being cross-linked with zinc oxide or magnesium oxide.
Copolymers of chloroprene with acrylic acid and/or methacrylic acid containing
from 1 to 7% by weight, preferably from 3 to 5% by weight of carboxylic acid
units incorporated by polymerisation are particu1arly preferred.
A mixture of the above mentioned latex and a flame retarding compound
is used for impregnating the polyurethane foam. The flame retarding compounds
used in the present invention is aluminium hydroxide.
A particularly suitable impregnating mixture is pre
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pared by incorporating aluminium hydroxide in a polychlorcprene latex containing
carboxyl groups, the quantity of aluminium hydroxide incorporated being approxi-
mately 1 to 5 times by weight, preferably 1 to 2 times by weight, based on the
solids content of the latex. In order to facilitate the incorporation of
aluminium hydroYide and obtain a stable latex, surface active substan oes such as
ethoxylated alkyl phenols and/or sulphonated wetting agents such as aIkyl sul-
phonates are generally added in quantities of from 5 to 10% by weight, based on
the latex. Silicone oil emulsions may also be added to prevent exoessive foam-
ing.
In addition to aluminium hydroxide, other flame retarding ccmpounds,
e.g. halogenated hydrocarbons such as pentabrcmltoluene and/or antimony trioxide
may be added to the latex in quantities of from 5 to 30% by wt., based on the
latex. Such a preferred impregnating mixture also contains magnesium oxide or
zinc oxide which serve partly as cross-linking agents for the elastomer. The
~ixture contains the cross-linking agent in a quantity of from 1 to 3 mol, pre-
ferably from 1.5 to 2.5 mol, based on 1 mol of carboxyl groups of the elastomer.
Ihe total amount of zinc oxide or magnesium oxide in the mixture is from 5 to 15
parts by weight, preferably from 7.5 to 10 parts by weight, based on 100 parts
by weight of dry rubber substance.
In addition to the constituents mentioned above, the mixture may also
contain other additives such as pigments and age resistors.
me mixture used for the treatment of the polyurethane foam which is
obtained, for example, from a polychloroprene latex by addition of the above men-
tioned constituents, is in the form of a dispersion or suspension generally hav-
ing a solids content of from 40 to 80% by weight, preferably of from 60 to 70%
by weight. The quantity of mixture used for treating the polyurethane foam de-
pends mainly upon the requirement of fire resistance which the laminate of the
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present invention is subsequently required to meet. The polyurethane foam is
generally treated with 0.1 to 10 times its weight of the mixture so that the
solids content of substance taken up thereby amounts to from 10 to 1,000%, pre-
ferably fram 15 to 350~ of its original weight. The polyurethane foam may be
completely or only partly impregnated, e.g. only on its surface. The mixture
may then be applied accordingly by spraying, casting, immersion, slop padding or
~ith doctors. For complete impregnation of the polyurethane foam the laminate
may be saturated, for example with the mixture, e.g. by immersing it in the mix-
ture and then sq~eezing off the exoe ss.
After the treatment, the moisture in the polyurethane foam is removed
by drying at an elevated temperature and the elastomer introduced into the poly-
urethane foam is cross-linked. me presence of zinc oxide or magnesium oxide as
cross-linking agents in the latices containing carboxyl groups has the advantage
that cross-linking of the elastamers will take place at the temperature used for
drying, i.e. at about 100C or slightly higher.
m e laminates of the present invention have the advantage that their
flame resistance can easily be adjusted according to the required specifications
and fire characteristics. Both the quantity of latex mixture used for impregna-
tion and the camposition thereof can be varied for this purpose by a suitable
choice of the elastomers and of the nature and quantity of the flame retarding
compounds and other additives. Multi-layered laminates consisting of sheetings
bonded with polyurethane foam on both sides afford a special advantage in that
they are very soft, flexible materials which are in no way hardened and are there-
fore suitable for the manufacture of very oomfortable reclining furniture. In
addition, the laminates of the present invention have very high dimensional
stability and can easily be manufactured and processed as endless goods on con-
tinuously operating machines.
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Additionally they have the advantage of being easier to handle on tex-
tile finishing machines such as spread coating, slop padding and impregnating
apparatus than flexible polyurethane foam used alone. ~he material is more
easily and firmly supported and guided by virtue of its laminate base, e.g. in
the form of a continuous textile web. This is particularly important where the
material is subjected to lateral pull, e.g. in tenter frames.
The following example further illustrates the present invention.
Example
An 8 mm thick laminate was produoe d in each case by flame laminating
polyester or polyether urethane foam on a cotton fabric (150 g/m ) and the foam
was then impregnated with a latex mixture cc~ntaining the follcwing main con-
stituents.
104 parts by weight of a 50% by weight latex of a copolymer of 96% by
weight of chloroprene and 4% by weight of methacrylic acid; 116 parts by weight
of a mixture of aluminium hydroxide/water/pentabromotoluene/antimony trioxide/
zinc c~icle in proportions by weight of 50:25:6:4:3 and l paxt by weight of an
organic red pigment suspended in 2 parts by weight of water.
m e mixture was applied to the laminate using slop padding rollers so
that the laminate was completely impregnated with the mixture. After drying at
130 C, the laminate shcwed a weight increase of 300%. The laminates obtained
were tested for their flame resistance according to DIN 4102, ASTM D 1692-74 andVehicle Safety Standard No. 302. m ey were also tested by the application of
methamine tablets ("Pill test") and by the application of burning cigarettes
("California Test") as ignition sources. The results of the tests were positive
and showed the efficient inhibition of fire by the laminates of the present inven-
tion.
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