Note: Descriptions are shown in the official language in which they were submitted.
35~
The present invention relates to a solution wel-
ding agent or medium for bonding; i.e., welding together
molded articles or components, especially flat articles,
such as sealing sheets of synthetic resins, which agent
contains a solvent mixture or a solvent mixture with dissolved
synthetic resin, respectively.
The present invention also relates to a process
for solution welding of molded articles, especially flat
shapes such as sealing sheets Eor the construction industry
made of solution-weldable synthetic resins.
Solution welding is a type of bonding for two
components, especially based on the same material, wherein
the mutually facing surfaces to be bonded together are
softened by means of a readily volatile solvent and pressed
against each other. After volatilization of the solvent,
a homogeneous bond is obtained without an intermediate layer
of a heterogeneous material. Solution welding can be uti-
lized in a large sector of thermoplastic synthetic resins;
in this connection, reference is had, for example, to the
known solution welding of sealing sheets of plasticized PVC
or polyisobutylene, described, for instance, in the book
Bauen mit Kunststoffen (Building with Synthetic Resins) by
Hansjurgen Saechtling, Carl Hanser Publishers, Munich tl973),
pages 127, 235 and 237, etc. A specific solution welding agent
containing a solvent and/or a solvent mixture as well as
synthetic resin additives, especially for polyisobutylene
sheets, is described, for example, in DAS (German Published
Application) 2,506,881.
The conventional solution welding agents, for
example, on the basis of tetrahydrofuran for plasticized
PVC, or petroleum spirits or carbon tetrachloride or cyclo-
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. . ~
: ! J
~Z~3~
hexanone for polyisobutylene are, however, incapable of
solution welding, with sufficient homogeneousness, molded
articles on the basis of elastomeric synthetic resins,
especially on the basis of ethylene-propylene-diene terpo-
lymers or ethylene-propylene copolymers. The invention is
based on the object of discovering a suitable solution
welding agent and a process technique to homogeneously bond
together molded articles on the basis of elastomeric synthetic
resins, likewise utilizing the solution welding method.
According to the present invention there is pro-
vided a process for the solution welding of molded or shaped
polymeric articles formed of solution-weldable synthetic
resin, to one another, which comprises applying a solution
welding agent to one or both of the synthetic resin surfaces
to be bonded together, said agent containing an organic
solvent mixture or an organic solvent mixture containing
synthetic resin dissolved therein, and then pressing the
surfaces to be bonded against each other; the molded synthetic
resin articles being formed of an ethylene-propylene~diene
terpolymer and/or ethylene-propylene copolymer co~taining
conventional additives for said resin, and said solvent
mixture containing 20-60% by volume of an aromatic solvent
and 80-40% by volume of an alipahtic solvent with a boiling
range of 60-160C-
Preferably, in the process the solution weldingagent may contain 75-90% by weight of the solvent mixture
and, dissolved therein, 25-10% by weight of elastomeric syn-
thetic resin on the basis of EPDM and/or EPM dissolved therein.
Preferably, the solvent mixture may contain 20-30%
by volume of toluene and 80-70% by volume of petroleum
spirits with a boiling range from 95 to 160C for solution-
welding the molded synthetic resin articles at temperaturefrom 15 and thereabove.
Preferably, the solvent mixture may contain 40-60%
by volume of toluene and 60-40% by volume of petroleum spirits
with a boiling range from 60 to 95C for solution-welding
the molded synthetic resln articles at temperatures from
5C and thereabove.
The resin articles are preferably devoid of vulca-
nization accelerator and contain additives.
The additives may comprise: fillers which may
comprises carbon black, silicic acid anhydride and silica,
extenders, stabilizers, antiaging compounds, mold release
agents, processing aids, or pigments.
According th the present invention there is also
provided process for the solution welding of molded or shaped
polymeric articles formed of a synthetic resin comprising
an ethylene-propylene-diene terpolymer and/or ethylene-
propylene copolymer that is devoid of vulcanization accele-
rator and contains conventional additives for said resin,
to one another, which comprises applying a solution welding
agent to one or both of the synthetic resin surfaces to be
bonded together, said agent containing an organic solvent
mixture or an organic solvent mixture containing said synthetic
resin dissolved thereln, and then pressing the surfaces to
be bonded against each other; said solvent mixture containing
20-50% by volume of an aromatic solvent and 80-40~ by volume
of an aliphatic solvent with a boiling range of 60-160C
and the applying of the solution welding agent and the pressing
of the surfaces against each other being effected at tempera-
ratures starting at 5C and thereabove.
.
~22~ 6
Accord.ing to the present lnvention also provided
a process for the solut.ion welding of molded or shaped poly-
meric articles formed of a synthetic resin comprising an
ethylene-propylene-diene terpolymer and/or ethylene-propylene
copolymer that is devoid of vulcani.zation accelerator and
contains conventional additives for said resin, to one another,
which comprises applying a solution welding agent to one or
both of the synthetic resin surfaces to be bonded together,
said agent containing an organic solvent mixture or an organic
solvent mixture containing said synthetic resin dissolved
therein, and then pressing the surfaces to be bonded against
each other; said solvent mixture containing 20-60% by volume
of an aromatic solvent selected from the group consisting
of xylene and toluene and 80-40% by volume of an aliphatic
solvent comprises petroleum spirits containing 5 to 12
atoms with a boiling range of 60-160C and the applying of
the solution welding agent and the pressing of the surfaces
against each other being effected at temperatures starting at
5C and thereabove.
In the present invention, there is used a solution
welding agent for welding together molded or shaped polymeric
articles of synthetic elastomeric resins, on the basis of
ethylene-propylene-diene terpolymers and/or ethylene-propylene
copolymers, which comprises an organic solvent mixture con-
taining 20-60% by volume of an aromatic solvent and 80 40%
by volume of an aliphatic solvent with a boiling rang from
60 to 160C.
Preferably, the solution welding agent contains
customary additives.
It is possible by means of the solution welding
agent proposed in this invention to apply the
3~6
solution welding method even in case of the specific elasto-
meric synthetic resins recited above, and to obtain homo-
geneous, tight bonds with adequate dissolving effect (surface
dissolution) after evaporation of the solvent.
The essential aspect of the invention is the use
of a solvent mixture with an aliphatic proportion (or compo-
nent) and an aromatic proportion.
Toluene (methylbenzene) is preferably employed as
the aromatic proportion. Xylene is likewise possible as
the aromatic solvent, but toluene proves to be more effectlve.
~ suitable aliphatic solvent is, in particular,
petroleum spirits on the basis of a mixture of saturated
aliphatic hydrocarbons containing 5-12 carbon atoms. The
petroleum spirits can also contain additionally unsaturated
naphthenic and aromatic hydrocarbons is small amounts; e.g.,
1 to 5% by weight. An essential advantage of the solution
welding agent proposed in accordance with the invention is
its inexpensive manufacture.
Depending on the application range for processing,
varying compositions of the solvent mixture are provided
according to the invention. When solution welding is effected
at temperatures starting with 15C and above, a solution
welding agent is preferably utilized consisting essentially
of a solvent mixture containing 20-30% by volume of toluene
and 80-70% by volume of petroleum spirits with a boiling
range of 95-160C. ~owever, if circumstances make it neces-
sary to conduct the solution welding step at even lower tem-
peratures, then a solution welding agent is suggested in
accordance with this invention consisting essentially of a
solvent mixture containing 40-60% by volume of toluene and
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,~ ,
60-40% by volume of petroleum spirits with a boiling range
of 60-95C. With this agent, the process can be carried out
at a temperature as low as 5C and above. It may be advanta-
geous for certain bonding areas of molded synthetic resin
articles, for example also the filling of joints or the use
of smaller amounts of solvent, to add to the solvent mixture
a dissolved synthetic resin.
A preferred composition of such a solution welding
agent provides the use of 75-90% by weight of solvent mixture
and 25-10% by weight of elastomeric synthetic resin on the
basis of EPDM and/or EPM dissolved therein, optionally with
conventional additives for these elastomers. In this case,
the solvent mixture can be combined either with merely the
elastomeric synthetic resin or also a synthetic resin molding
composition additionally containing additives, such as sta-
bilizers, mold release agents, extenders, pigments, carbon
black. However, it is more pratical not to add fillers,
such as chalk, talc, silica, etc., as additives to the solu-
tion welding agent, since this addition could reduce the
strength of the welding bond.
Generally, the sheet comprises from 40 to 58%
by weight of the fillers; whereas the other additives may
25 vary from 7 to 18% by weight and 35 to 46 by weight of elasto-
meric resin.
The sealing sheet material, used in the present
invention, combines advantageously the benefits of the
elastomeric, vulcanizable but not completely vulcanized
synthetic resinsl especially regarding weathering stability,
with the benefits provided by the thermoplastic synthetic
resins; namely, weldability, especially solution weldability,
attained by means of the solution welding agent proposed by
-- 6
the present invention.
The multiple-layer sealing sheet material can be
manufactured, for example, by calendering of sheets, espe-
cially in thicknesses of 0.6 to 0.9 mm, in accordance withthe individual layers, and rolling or laminating these sheets
together with the use of heat and pressure, with the embed-
ding of the reinforcing insert therein. It is economical,
in this connection, to employ the same sheeting for each
of the outer layers.
In a advantageous composition of the sealing sheet,
the synthetic resin layers may contain the following:
35-46% by weight of EPDM or EPM or mixture of
EPDM or EPM
40-58% by weight of fillers, of these up to 50
by weight of carbon black
5-12% by weight of extenders
10- 0.1% by weight of stabilizers and antiaging
coupounds
5- 1.9% by weight of mold release agents and
auxiliary processing media.
Preferably, the layers contain as fillers:
19-22% by weight of carbon black, reinfcrcing
or semi-reinforcing types
26-31% by weight of silicic acid anhydride or
of silica (silicic acid anhydride and
kaolinite with a particle size smaller
than 20 ~m and at least 40% proportion
of smaller than 2 ~m3,
based on 100% by weight of layer, for an economical manufac-
ture of the sealing sheet, for improving the strength, and as
a processing aid. This composition provides good processa-
bility, especially, suitability for calendering.
The elastomeric synthetic resins selected are in
particular, partially crys-talline ethylene-propylene-diene
terpolymers (EPDM) or partially crystalline ethylene-pro-
pylene copolymers (EPM) and/or mixtures thereof in order to
ensure the high demands to be met by a sealing sheet with
respect to mechanical properties, low-temperature stability,
perforation strength even at higher temperatures, low shrinkage,
tear strength, extensibility, and dimensional stability. An
EPM is preferred with an ethylene content of 65% by weight
or larger and a propylene content of 35% by weight or smaller
and an EPDM is preferred with an ethylene content of at least
65% by weight, a propylene content of not more than 30% by
weight and maximally up to 8% by weight of a diene component,
preferably less than 5~ by weight of a diene component. A
suitable diene component is, for example, ethylidene norbornene
hexadiene or cyclopentadiene. The minimum degree of partial
crystallinity of the EPDM or EPM employed is determined
according to the DSC method in a differential scanning calori-
meter measuring the melting curve. The maximum of the melting
peak, measured at temperature TS in C according to the DSC
curve is designated as an endothermal peak which can be verynarrowly defined, but can also encompass a range. With
ethylene-propylene terpolymers, the temperature TS is in the
range around 50C. The amount of heat required for melting,
the so-called melting heat ~Hs, likewise measured according
to the DSC method, then yields information on the presence
of crystalline blocks in the ethylene-propylene-diene ter-
polymer or ethylene-propylene copolymer. Those partially
crystalline EPDM or EPM elastomers with a melting heat of
at least 10 J/g are preferably employed.
For selecting suitable elastomeric synthetic resins,
especially EPDM and EPM, the strength thereof is likewise of
importance, those EPDM and EPM being utilized which exhibit
a tear strength of at least 5 N/mm measured according to
3~
DIN 53 455 (~erman Industrial Standard).
The high parting strength of at least 100 N/5 cm
of the multiplelayer sealing sheet is attained especially by
choosing suitable reinforcing inserts with correspondingly
large air interspaces between the warp and weft threads,
making i~ possible for the synthetic resin layers to extend
therethrough to an adequate degree and thereby to form a
substantially homogeneous bond. In this connection, glass
fabrics are preferably employed, imparting to the multiple-
layer sealing sheet a high dimensional stability and diminish-
ing the shrinkage, much feared in the building industry,
under alternating temperature stresses during the course
of summer/winter weathering.
~ ikewise of decisive importance is the selection
of suitable fillers for the synthetic resin layers and
additives which cooperate synergistically and which improve
the properties of the sealing sheet, especially its mechanical
characteristics. In this connection, an essential component
is constituted by semiactive or active carbon blacks, so-
called reinforcing blacks, wherein the layers contain between
19 and 25~ by weight, preferably 19-22% by weight of carbon
blacks. For example, suitable are carbon blacks produced
according to the furnace method exhibiting average particle
sizes of between 30 and 60 nm and a BET surface of between
30 and 60. Especially the carbon black improves the strenght
of the sheet and improves the processability.
As reinforcing filler and simultaneously for making
the product less expensive, silicic acid anhydride or silica
is preferably employed; i.e., silica is a mixture of silicic
acid anhydride and kaolinite, wherein the particle sizes
should be smaller than 20 ~m, and of these at least 40%
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~2Z~
should be smaller than 2 ~m. ~owever, it is also possible
to replace up to 2/3 of the silica proportion by other selected
fillers, likewise in a very fine-grained form, such as chalk,
kaolin, talc, baryte, silicic acid anhydride and/or glass
fibers, or mix-tures thereof.
Additionally, the layers of the sealing sheet con-
tain stabilizers and antiaging agents, especially on the basis
of sterically hindered phenolic antioxidants, phenolic phosphites,
thioesters of aliphatic carboxylic acids, and similar materials.
Especially suitable as mold release agents for processing
are metallic soaps, for example, calcium soaps, calcium
stearate, zinc stearate, and as auxiliary processing agents
especially montanic acid esters and/or hydrogeneted hydro-
carbon resins. Moreover, for processing EPDM and EPM, the
use of extender oils on an aliphatic and/or naphthenic basis
is required. A preferred structure for the synthetic resin
layers according to the invention provides that they contain
35-46% by weight of EPDM and/or EPM, 31-26% by weight of
fillers, such as chalk, kaolin, talc, baryte, silicic acid
anhydride and/or glass fibers in mixtures with silica or
solely silica, 12-7% by weight of aliphatic and/or naphthenic
extender oils, 1.0 - 0.1% by weight of stabilizers and
antiaging agents on the basis of sterically hindered phenolic
antioxidants, phenolic phosphites, thioesters of aliphatic
carboxylic acids or the like, 25-19% by weight of reinforcing
carbon blacks, 5.0 - 0.1% by weight of mold release agents
on the basis of metallic soaps, 2.3 - 1.8% by weight of
processing aids, such as montanic acid esters, hydrogenated
hydrocarbon resins. Additionally t the sealing sheet can
be provided with other customary additives, such as pigments
for coloring and other materials.
The properties of the sealing sheet of this
invention are excellently adapted to all demands to be met
in the building industry. Besides showing high performance
_ g
3~
at room temperature, the sealing sheet performs at low
temperatures of down to -60 C as well as at high temperatures
up to about 100C. Weathering stability and biological
resistance are likewise present.
It is, moreover, an objective of the invention to
provide a sealing sheet on the basis of elastomeric synthetic
resins which can be bonded also by means of the well-proven
solution welding or room-temperature welding (cold welding)
method. The sealing sheet can be solution-welded advan-
tageously by means of a solution welding agent on the basis
of a mixture of toluene and petroleum spirits, it being
possible to produce seam bonds of flawless quality starting
with temperatures as low as above 0C, especially above 5C,
in the open air at the building site~
The following examples serve for explaining the
invention without limiting same.
EXAMP~E 1
For obtaining the multiple-layer sealing sheet
material according to the sole figure in the accompanying
drawing, sheets having a thickness of 0.75 mm made up of
a material composition A according to Table 1, are utilized
for the outer layers 1, 3; and a glass fabric with a weight
per unit area of 30 g/m2 with a nonslip finish on the basis
of vinyl propionate dispersion is used for the reinforcing
insert 2; these layers are combined into the multiple layer
sealing sheet by calendering.
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TABLE 1
_ _ _ __
Composition A Parts by Weight
_ .
EPDM with
67% by weight ethylene
27% by weight propylene
6% by weight ethylidene 40.0
norbornene
s 14 J/g, 2
Tear strength 11.2 N/mm
_ _ ~ - ~ ~
Sillitin*(Silica) 27.0
I _ i .
Extender oil 8.0
Hydrocarbon resin 2.0
_ .
Carbon black, semiactive 22.5
Calcium soap 0.3
Antioxidants 0.2
The thus-produced multiple-layer sealing sheet has
the following properties:
Thickness DIN 53370 1.5 mm
Tear strength DIN 53354 longitudinal/
transverse, fabric
~400/ >400 N/5 cm
* Sillitin is a Trade mark
3~
Tear strength DIN 53354 longitudinal/transverse,
sheet
>450/ >450 N/5 cm
Elongation at rupture DIN 53354 long.itudinal/transverse,
fabric
2/2%
Elongation at rupture DIN 53354 longitudinal/transverse,
sheet
>450/ >450~
Specific gravity DIN 53479 1270 kg/m3
Parting strength of
layers DIN 53357 ~100 N/5 cm
Dimensional change at + ~0C, 6 hour period DIN 53377 <0.5%
Cold impact strength VDCH 22-02 218 K
To weld the sealing sheets together with one
another, the solution welding agent employed is, for example,
a mixture of 1 part by volume of toluene and 3 parts by
volume of petroleum spirits with a boiling range from 100
to 140C. The sealing sheet is welded in this case at
temperatures starting from 15C on upward by coating the
overlapping seams of the sheets to be welded in a width of
about 5 to 8 cm with a brush or the like with the solution
welding agent and continously directly after the coating the
seams are pressed together with a pressure of about 0,01 to
0~1 N/cm2 during a time of about 10 to 30 sec. by means of
a sandbag or pressure roll.
If the above-described sealing sheets are to be
welded together at even lower temperatures, the step can be
performed, for example, with a solution welding agent made
up of 1 part by volume of toluene and 1 part by volume of
petroleum spirits with a boiling range from 60 to 95C, in
which case the operation can be performed even starting at
temperatures of 5C on upward in the outside air, and
adequate venting and evaporation of the solvents is possible
- ~.2 -
to establish a flawless homogeneous bond by means of solution
welding. In case the temperature during installation i~
very low, 5C or less, it is possible to warm up the sheets
by hot air before or after applying the solution welding
agent to accelerate the welding.
EXAMPLE 2
For the solution welding of joints and optionally
for the securing of seam junctions, or the like, it is also
possible to employ a solution welding agent which contains
a synthetic resin dissolved therein. For the sealing sheet
of the composition set forth in Table 1, for example, a so-
lution welding agent, called "liquid film," having the follow-
ing composition is utilized for securing of joints:
84% by weight of solvent mixture made up ot
3 parts by volume of petroleum spirits,
boiling point 100-160C, and 1 part by
volume of toluene
16% by weight of a synthetic resin composition
of 40 parts by weight of EPDM (according
to Table l);
8 parts by weight of extender oil;
2 parts by weight of hydrocarbon resin;
22.5 parts by weight of semiactive carbon
black;
0.3 part by weight of calcium soap; and
0.2 part by weight of antioxidants.
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