ADHESIVE AND SEALING SUBSTANCE BASED ON RUBBER AND PROCESS FOR THE CONNECTION OR BONDING OF COMPONENTS OR STRUCTURAL PARTS

ADHESIF ET PRODUIT D'ETANCHEITE A BASE DE CAOUTCHOUC ET PROCEDE D'APPLICATION

English Abstract

Adhesive and sealing substances based on rubber are disclosed
which in addition to the usual components contain stereo-specific
OH-terminated polybutadiene-liquid rubber as the main
component and thus have an improved adhesion and an improved
breaking behaviour. The adhesive and sealing substances
disclosed are particularly suitable for use in car manufacture.

Claims

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Claims:
1. Adhesive and sealing substance based on rubber containing
a) 15 to 50 % by weight of stereo-specific polybutadiene-
liquid-rubber,
b) 2 to 10 % by weight of stereo-specific cis-1,4-poly-
butadiene-solid-rubber,
c) 2 to 10 % by weight of sulphur,
d) 0.5 to 10 % by weight of an organic accelerator or an
accelerator system, and
e) 30 to 70 % by weight of fillers,
characterised in that it contains OH-terminated
polybutadiene as component a).
2. Adhesive and sealing substance according to claim 1,
characterised in that the OH-terminated polybutadiene
has an OH-functionality of 2.0 to 3.0, a molecular
weight of 1000 to 5000 and a viscosity of 0.5 to 10 Pas at 30°C
and has at least 50 % of the unsaturation in the
trans-1,4-configuration and at least 10 % of the unsaturation in
the cis-1,4-configuration.
3. Adhesive and sealing substance according to claim 1
further containing 2 to 10 % by weight of adhesion
promoter.

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4. Process for the connection or bonding of components or
structural parts, characterised in that a coating is
formed with an adhesive according to one of the claims
1, 2 or 3 on at least one of the surfaces of the
components or structural parts which are to be bonded,
before or after these components or structural parts
are assembled, and if this has not yet occurred, heated
after the components or structural parts have been
joined together in order to harden the adhesive
substance.
5. Process according to claim 4, characterised in that
components or structural parts are bonded in car
manufacture.
6. Process according to claim 5 wherein the components or
structural parts are of metal.
7. Process according to claim 6 wherein the components or
structural parts are oiled metal surfaces.

Description

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The invention relates to low-viscosity adhesive and sealing
substances based on rubber which are easily pumped at in-
creased temperatures and which can be vulcanised with the
usual crosslinking systems.
Solvent-free adhesive and sealing substances based on rubber,
which are particularly suitable for use in car manufacture,
have been known for some time. An overview of the development
in the area is provided by the explanations in the European
Patent Specification 97 394 and the European Patent Applica-
tion 256 316. However, these known adhesive and sealing sub-
stances were still not completely satisfactory, and therefore
in EP-PS 97 394 the use of liquid polybutadiene which has at
least 40 $ of the unsaturation in the 1,4-configuration is
proposed. Preferably, the liquid polybutadiene is mixed with
small quantities of solid rubber, particularly solid polybuta-
diene.
In the European Patent Application 256 316 it is, however,
stated that even the adhesive and sealing substances known
from EP-PS 97 394 still have considerable defects. It is
therefore proposed that instead of solid rubbers such as solid
polybutadiene one or more chemically irreversibly depolymer-
ised solid rubbers of natural or synthetic origin are added in
quantities of 1.5 to 5 ~S by weight. Thus the adhesives should
show a better Theological behaviour. It has proved, however,
to be the case that the adhesive and sealing materials accord-
ing to the European Patent Application 256 316 not only have
the disadvantage of the additional process step of depolymeri-
sation but in addition, just as the adhesive and sealing
substances known from EP-PS 97 394, still do not have optimal
adhesive properties.

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The object of the invention is therefore to improve adhesive
and sealing substances of the type known from EP-PS 97 394 and
the European Patent Application 256 316 and in particular
their adhesion to metal and their breaking behaviour.
To achieve this object an adhesive and sealing substance based
on rubber containing
a) 15 to 50 $ by weight of stereo-specific polybutadiene-
liquid-rubber,
b) 2 to 10 ~ by weight of stereo-specific cis-1,4-poly-
butadiene-solid-rubber,
c) 2 to 10 ~ by weight of powdered sulphur,
d) 0.5 to 10 ~ by weight of an organic accelerator or an
accelerator system,
e) 30 to 70 ~S by weight of fillers and optionally
f) 2 to 10 $ by weight of adhesion promoter,
is proposed which is characterised in that it contains OH-
terminated polybutadiene as component a).
The preferred adhesive and sealing substances according to the
invention contain 30 to 40 $ by weight of component a), 3 to
5 ~ by weight of component b), 3 to 5 ~ by weight of component
c), 0.5 to 2 ~ by weight of component d), 50 to 70 ~k by weight
of component e) and optionally 3 to 10 ~ by weight of com-
ponent f). Moreover, the adhesive and sealing substances
according to the invention can contain further usual con-
stituents such as anti-ageing agents, thixotropic agents,
antioxidants etc.

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The desired improvement in the adhesive and breaking proper-
ties of the adhesive and sealing substances according to the
invention is achieved by the use of OH-terminated liquid
polybutadiene. Preferably, the liquid OH-terminated polybuta-
diene has an OH-functionality of 2.0 to 3.0, a molecular
weight of 1000 to 5000, a viscosity of 0.5 to 10 Pas (at
30° C) and has at least 50 ~ of the unsaturation in the trans-
1,4-configuration and at least 10 ~ of the unsaturation in the
cis-1,4-configuration. An example of a suitable liquid OH-
terminated polybutadiene has a molecular weight of 2800 and an
OH-functionality of 2.4 to 2.6, in which 60 $ of the unsatura-
tion is distributed on the trans-1,4-configuration, 20 ~ of
the unsaturation is distributed on the cis-1,4-configuration
and 20 g of the unsaturation is distributed on the 1,2-con-
figuration.
All other components correspond to the prior art so that for
this one can refer to EP-PS 97 394 and the European Patent
Application 256 316. It should, however, be mentioned that the
unsaturation of the component b) in the cis-1,4-configuration
should amount to at least 96 ~. The application of the ad-
hesive and sealing substances according to the invention also
has no peculiarities and takes place in the known manner as
described in the above mentioned publications.
The liquid OH-terminated polybutadienes that can be used
according to the invention, and which are usually obtained by
emulsion polymerisation, are known from polyurethane chemistry
and are used there to introduce so-called "soft segments". Due
to the terminal OH-groups contained in them the adhesive and
sealing agents according to the invention provide a consider-
ably improved adhesion to metal compared with similar agents
containing polybutadienes which are not OH-terminated. Shear-
ing strength test bodies which have been prepared with the
adhesives according to the invention thus consistently show a
cohesive appearance of fracture after vulcanisation and break-

CA 02000569 2000-O1-24
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ing, while there is a tendency towards adhesive fracture when a sealing
substance is used
on the basis of a liquid polybutadiene which is not specifically OH-
terminated.
The connection or bonding of components or structural parts can be effected
using the
adhesive and sealing substances of the present invention. The connection or
bonding of
components or structural parts can be effected by forming a coating with an
adhesive on at
least one of the surfaces of the components or structural parts which are to
be bonded,
before or after these components or structural parts are assembled, and if
that has not yet
occurred, heated after the components or structural parts have been joined
together in order
to harden the adhesive substance.
The process can be used to bond components or structural parts in car
manufacture. The
components or structural parts can be of metal and in a preferred embodiment
are oiled
metal surfaces.