Note: Descriptions are shown in the official language in which they were submitted.
"EPDXY RESIN COMPOSITION WITH REDUCED TOXICITY"
[0002] The present invention relates to a two-component adhesive based
on a specific epoxy resin system. The epoxy resin system according to the
present invention makes it possible to provide, without the use of components
that are categorized as toxic, irritating, or sensitizing and that would
require
corresponding labeling under European law, adhesives that are equivalent in
quality to conventional adhesives in terms of utilization properties.
[0003] Epoxy-based resin systems have been successfully used for some
time as adhesives or repair compounds for consumers, hobbyists, and
craftsmen, and in the aviation, automotive, or electrical industry, as
adhesives
or sealants or for the coating of surfaces, or as resin systems with a number
of
different materials for the manufacture of composite materials. Hardenable
formulations that contain epoxy/hardener mixtures are suitable in particular
as
structural adhesives. One important property of the unhardened resin system is
its viscosity, which is significant in terms of handling and processability.
Important material properties of the hardened formulations are, among others,
adhesive power (often determined as tensile shear strength) and modulus of
elasticity.
[0004] Reactive epoxy resin systems of the existing art often contain
constituents that have been categorized as toxic, irritating, sensitizing,
and/or
hazardous to water resources, and can result, for example, in contact
dermatitis during processing. According to European law, such preparations
must be provided with the corresponding hazard label (e.g. C, Xn, Xi, N). For
reasons of environmental protection, safety, and industrial hygiene, there is
a
desire for reactive epoxy resin-containing preparations that do not require
labeling under European law and that exhibit a reduced sensitizing potential,
but that meet technical requirements with regard to processability and
adhesive properties.
[0005] It is known that reactive epoxy resins having a molar weight above
700 g/mol are not sensitizing and are not subject to labeling requirements.
CA 2788739 2017-09-14
Examples thereof are high-molecular-weight solids based on DGEBA
(diglycidyl ethers of bisphenol A), and liquid epoxy-terminated polyethers
with a
high epoxy equivalent weight. These do not, however exhibit the viscosity
properties necessary for processing prior to curing, and/or the necessary
strength properties after curing. High-molecular-weight solid epoxy novolacs
have the high epoxy functionality necessary for high strength (and,
correspondingly, a low epoxy equivalent weight), but are not processable
because of their high viscosity at room temperature.
[0006] An object of the present invention was therefore to develop a
hardenable epoxy resin that is advantageous in toxicological and
dermatological terms and nevertheless has no disadvantages in the context of
utilization properties, in particular viscosity during processing and/or
strength
after curing.
[0007] It has now been found, surprisingly, that suitable mixtures of
different
reactive epoxy resins result in the desired property combination of freedom
from labeling requirements, processability, and adhesive properties.
[0008] A first subject of the present invention is therefore a two-
component
composition
whose first component is a mixture of reactive epoxy resins and optionally
further formulation constituents which contains, based on the mass of all
epoxy
resins,
a) at least 10 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy
equivalent weight of at least 250 g/eq, and
b) at least 10 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent
weight of at least 175 g/eq,
and
whose second component contains at least one thiol group-containing
hardener for epoxy resins.
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[0008A] In one embodiment, there is provided a two-component
composition comprising a first component and a second component, wherein
the first component is a mixture of reactive epoxy resins comprising, based on
the mass of all epoxy resins,
a) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq;
b) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight of
at
least 175 g/eq;
c) 10 to 40 wt% of an epoxy group-containing reaction product of
epichlorohydrin with bisphenol A which has an epoxy equivalent weight of at
least 500 g/eq; and
d) optionally, further formulation constituents; and
wherein the second component contains at least one thiol group-containing
hardener for epoxy resins; and
wherein the two-component composition, upon cure, has a tensile shear
strength of greater than 8 MPa, measured in accordance with DIN EN 1465.
2a
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[0009] According to the present invention, a "reactive epoxy resin" is
understood as a prepolymer that has an average epoxy functionality greater
than 1. Because of the reactive epoxy groups, the prepolymer can be reacted
with further molecules (called "hardeners") that are reactive with respect to
epoxy groups, and thereby be "cured" or "hardened."
[0010] The composition according to the present invention contains, as a
first component a) essential to the invention, at least 10 wt% of an epoxy
group-containing reaction product of epichlorohydrin with polypropylene glycol
which has an epoxy equivalent weight of at least 250 g/eq.
[0011] In a preferred embodiment, the composition according to the
present
invention contains 10 to 60 wt% of component a). A quantity range from 30 to
45 wt% is especially preferred. The quantity indications refer in each case to
the mixture of all epoxy resins, without the further formulation constituents.
[0012] In the context of the work on which this invention is based, it
was
possible to show that epoxy group-containing reaction products of
epichlorohydrin with polypropylene glycol having an epoxy equivalent weight of
at least 300 g/eq exhibit particularly advantageous properties.
[0013] Particularly preferred components a) are, according to the present
invention, the reactive epoxy resins marketed by the Dow company under the
commercial designations DER 732 (EEW 310 to 330 g/eq) and DER 732P
(EEW 310 to 330 g/eq).
[0014] It is particularly advantageous according to the present invention
if
corresponding epoxy group-containing reaction products of epichlorohydrin
with polypropylene glycol having an epoxy equivalent weight of less than 300
g/eq are contained in the compositions at a proportion of at most 3 wt%, in
particular at most 1 wt%, based in each case on the first component made up
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of a mixture of reactive epoxy resins and optionally further formulation
constituents.
[0015] As a second component b) essential to the invention, the
composition according to the present invention contains at least 10 wt% of an
epoxy group-containing reaction product of epichlorohydrin with a novolac
resin
which has an epoxy equivalent weight of at least 175 g/eq.
[0016] In a preferred embodiment, the composition according to the
present
invention contains 10 to 85 wt% of component b). A quantity range from 30 to
45 wt% is especially preferred. The quantity indications refer in each case to
the mixture of all epoxy resins, without the further formulation constituents.
[0017] In the context of the work on which this invention is based, it
was
possible to show that epoxy group-containing reaction products of
epichlorohydrin with a novolac having an epoxy equivalent weight of at least
180 g/eq, and in particular of at least 190 g/eq, exhibit particularly
advantageous properties.
[0018] Novolacs preferred according to the present invention are the
polycondensation products of formaldehyde with phenol and/or cresol.
[0019] It has furthermore proven to be advantageous if the reaction
products of epichlorohydrin and novolac have an epoxy functionality of at
least
3, in particular of at least 3.5.
[0020] Reaction products of epichlorohydrin and novolac which have an
epoxy equivalent weight of at least 175 g/eq and simultaneously an epoxy
functionality of at least 3 were found to be particularly convincing in terms
of
the objects stated according to the present invention. Reaction products of
epichlorohydrin and novolac having an epoxy equivalent weight of at least 180
g/eq and an epoxy functionality of at least 3, in particular reaction products
of
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epichlorohydrin and novolac having an epoxy equivalent weight of at least 190
g/eq and an epoxy functionality of at least 3.5, are particularly preferred.
[0021] The desired property combination of processability prior to
curing,
and adhesion strength after curing, are most effectively achieved thereby.
[0022] Particularly preferred components b) are, according to the present
invention, the reactive epoxy resins marketed under the commercial
designations DEN 439 (EEW 191 to 210 g/eq, functionality 3.8; Dow), Araldite
ECN 1299 (cresol-formaldehyde novolac, EEW 235 g/eq, functionality 2.5 to
5.5; Huntsman), Epikote 154 (EEW 176 to 181 g/eq; Hexion). DEN 439 is very
particularly preferred according to the present invention.
[0023] It is particularly advantageous according to the present invention
if
corresponding reaction products of epichlorohydrin with novolac having an
epoxy equivalent weight of less than 175 g/eq are contained at a proportion of
at most 3 wt%, in particular at most 1 wt%, based in each case on the first
component made up of the mixture of reactive epoxy resins and optionally
further formulation constituents.
[0024] In order to ensure optimum processability of the compositions
according to the present invention, it has proven particularly advantageous
according to the present invention if the epoxy-containing compositions have
viscosities below 3000 Pas. Epoxy-containing preparations having a viscosity
below 500 Pas are very particularly preferred. Viscosity measurements are
accomplished according to the present invention at 25 C using a rheometer
and the following viscosity-dependent settings:
- at a viscosity < 0.25 Pa*s, measurement was performed using a cone and
plate (0.04 /25 mm) at a shear rate of 0 to 100/s;
- viscosities > 0.25 Pa*s and < 10,000 Pa*s were measured using parallel
plates (25 mm/25 mm) at a shear rate of 0 to 100/s; and
- viscosities > 10,000 Pa*s were measured using parallel plates (25 mm/25
mm) and at an angular frequency of 100 rad/s.
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According to the present invention, a measurement at a "shear rate of 0 to
100/s" is understood as a measurement in which the shear speed is increased,
within 100 s, from 0/s to 100/s. The shear speed is then held constant for 30
s,
and then the result is determined.
[0025] A further essential property of the agents according to the
present
invention is the so-called tensile shear strength. This is determined by means
of the following experimental setup:
[0026] Two sandblasted, cold-rolled steel specimens are wetted with the
adhesive to be tested, on an overlap area of 2.5 cm2 with a layer thickness of
0.2 mm, and bonded. After corresponding curing, the tensile shear strength of
the adhesive is tested in accordance with DIN EN 1465 at a rate of 15 mm/min.
[0027] It has proven to be advantageous according to the present
invention
if the adhesives exhibit, after they have cured, a tensile shear strength
above 8
MPa, in particular above 10 MPa. The speed of the curing process plays no
essential role in this context.
[0028] As a third component essential to the invention, the composition
according to the present invention contains at least one thiol group-
containing
hardener for epoxy resins.
[0029] According to the present invention, a "thiol group-containing
hardener for epoxy resins" is understood as a compound that comprises at
least two thiol groups per molecule. It is particularly preferred according to
the
present invention if the compound is one that is liquid at 22 C.
[0030] According to the present invention it may be preferred, in a
specific
embodiment, if the thiol group-containing hardener is a polymeric compound.
[0031] Thiol group-containing hardeners preferred according to the
present
invention are the compounds known by the commercial designations:
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- Capcure 3-800, Capcure 3830-81, Capcure LOF, Capcure WR6, Capcure
WR35, Capcure 40 SEC HV (Cognis),
- GPM 800, GPM 800 LO, GPM 830 CB, GPM 845 MT, GPM 888, GPM 890
CB, GPM 891, GPM 895 FC (Gabriel Performance Products),
- Karenz MT [pentaerythritol tetrakis(3-mercaptobutylate); CAS 31775-89-0]
(Showa Denko),
- dipentenedimercaptan (CAS 4802-20-4), Mercaptized Soy Oil, PM 407, PM
358, Mercaptized Castor Oil: 805-C (Chevron Phillips),
- Thiocure GDMA (glycol dimercaptoacetate; CAS 123-81-9), Thiocure
TMPMA (trimethylpropane trimercaptoacetate; CAS 10193-96-1), Thiocure
PETMA (pentaerythritol tetramercaptoacetate; CAS 10193-994), Thiocure
TMPMP (trimethylopropane tris-3-mercaptopropionate; CAS 33007-83-9),
Thiocure PETMP (pentaerythritol tetra-3-mercaptopropionate; CAS 7575-
23-7), Thiocure8 ETTMP (ethoxylated trimethyl
propane tris-3-
mercaptopropionate (polymer), CAS 345352-19-4) (Bruno Bock).
[0032] The
following compounds are also thiol group-containing hardeners
preferred according to the present invention:
- DMDO (3,6-dioxa-1,8-octanedithiol),
- hardenable DMDO reaction product,
- 3-oxa-1,5-pentanedithiol,
- 1,2-ethanedithiol T,
- 1,3-propanedithiol,
- 1,2-propanedithiol,
- 1,4-butanedithiol,
- 1,3-butanedithiol,
- 2,3-butanedithiol,
- 1,5-pentanedithiol,
- 1,3-pentanedithiol,
- 1,6-hexanedithiol,
- 1,3-d ithio-3-methylbutane,
- ethylcyclohexyldithiol (ECH DT),
- methylcyclohexyldithiol,
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- methyl-substituted dimercaptodiethyl sulfide,
- dimethyl-substituted dimercaptodiethyl sulfide,
- 2,3-dimercapto-1-propanol,
- bis-(4-mercaptomethylphenyl) ether,
- 2,2'-thiodiethanethiol.
[0033] Thiol group-containing hardeners that are particularly preferred
according to the present invention are:
- Capcure 3-800, Capcure 3830-81, and Capcure LOF (Cognis),
- GPM 800, GPM 800 LO, GPM 830 CB, and GPM 888 (Gabriel
Performance Products),
- Mercaptized Soy Oil, PM 407, PM 358, and Mercaptized Castor Oil 805-C
(Chevron Phillips),
- Thiocure ETTMP (ethoxylated trimethylpropane tris-3-mercaptopropionate
(polymer); CAS 345352-19-4) (Bruno Bock),
- 1,5-pentanedithiol,
- 1,3-pentanedithiol, and
- 1,6-hexanedithiol.
[0034] It may be preferred according to the present invention if the
second
component of the composition contains less than 25 wt%, in particular less
than 20 wt%, in particular less than 10 wt%, of one or more of the following
compounds, the quantity indications being based on the entire composition of
the second component:
- pentaerythritol tetrakis(3-mercaptobutylate) (CAS 31775-89-0),
- dipentenedimercaptan (CAS 4802-20-4),
- glycol dimercaptoacetate (CAS 123-81-9),
- trimethylopropane tris-3-mercaptopropionate (CAS 33007-83-9),
- pentaerythritol tetra-3-mercaptopropionate (CAS 7575-23-7),
- DMDO (3,6-dioxa-1,8-octanedithiol),
- 1,2-ethanedithiol,
- 1,3-propanedithiol,
- 1,4-butanedithiol,
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- 1,3-butanedithiol,
- 2,3-butanedithiol, and
- 2,3-dimercapto-1-propanol.
[0035] The thiol group-containing hardeners are used by preference at a
ratio of 1 thiol equivalent hardener per 1 to 2 epoxy equivalent. This means
that the utilization mixture preferably comprises an excess of reactive epoxy
groups with respect to the reactive thiol groups.
[0036] In a preferred embodiment of the present invention, the first
component further contains at least 10 wt% of an epoxy group-containing
reaction product of epichlorohydrin with bisphenol A which has an epoxy
equivalent weight of at least 500 g/eq.
[0037] In this embodiment, compositions that contain, based on the mass
of
all epoxy resins, the following components:
- a) 10 to 60 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
- b) 15 to 85 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq, and
- c) 0 to 70 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
are accordingly particularly preferred.
[0038] Compositions that contain, based on the mass of all epoxy resins,
the following components:
- a) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
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CA 2788739 2017-09-14
- b) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq, and
- c) 10 to 40 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
are particularly preferred according to the present invention.
[0039] Compositions that contain, based on the mass of all epoxy resins,
the following components:
- a) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
- b) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq and an epoxy functionality of at least 3, and
- c) 10 to 40 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
are furthermore particularly preferred according to the present invention.
[0040] It has proven to be particularly advantageous according to the
present invention if the composition according to the present invention
contains
0 to 70 wt% of an epoxy group-containing reaction product of epichlorohydrin
with bisphenol A which has an epoxy equivalent weight of at least 500 g/eq. A
quantity range from 10 to 40 wt% is especially preferred. The quantity
indications refer in each case to the mixture of all epoxy resins, without the
further formulation constituents.
[0041] In the context of the work on which this invention is based, it
was
possible to show that epoxy group-containing reaction products of
epichlorohydrin with bisphenol A having an epoxy equivalent weight of at least
560 g/eq exhibit particularly advantageous properties.
CA 2788739 2017-09-14
[0042] Epoxy group-containing reaction products of epichlorohydrin with
bisphenol A which have an epoxy equivalent weight of at least 500 g/eq that
are particularly preferred according to the present invention are the epoxy
resins marketed under the commercial designations:
- Epikote8 1002 (EEW 575 to 700 g/eq; epoxy functionality 2; Hexion),
- DER 662E (EEW 590 to 630 g/eq; epoxy functionality 2),
- Epon8 1002F (EEW 600 to 700 g/eq; epoxy functionality 2),
- DER 662UH (EEW 675 to 750 g/eq; epoxy functionality 2),
- DER 663U (EEW 730 to 820 g/eq; epoxy functionality 2),
- DER 664U (EEW 875 to 955 g/eq; epoxy functionality 2),
- Epon 1009F (EEW 2300 to 3800 g/eq; epoxy functionality 2; Hexion),
- Epon 1007F (EEW 1700 to 2300 g/eq; epoxy functionality 2; Hexion),
- Epon 1004F (EEW 800 to 950 g/eq; epoxy functionality 2; Hexion),
- DER 692H (EEW 660 to 720 g/eq; epoxy functionality 2; Dow),
- DER 692 (EEW 660 to 720 g/eq; epoxy functionality 2; Dow).
The products marketed under the commercial designations Epikote 1002,
DER 662E, and Epon 1002F are very particularly preferred according to the
present invention. Epon8 1002F is very particularly preferred according to the
present invention.
[0043] It is particularly advantageous according to the present invention
if
corresponding epoxy group-containing reaction products of epichlorohydrin
with bisphenol A which have an epoxy equivalent weight below 500 g/eq are
contained in the compositions at a proportion of at most 3 wt%, in particular
at
a proportion of at most 1 wt%, based in each case on the first component
made up of a mixture of reactive epoxy resins and optionally further
formulation
constituents.
[0044] Especially in toxicological terms, it has proven to be
advantageous if
the compositions according to the present invention contain, in addition to
the
aforesaid epoxy group-containing reaction products a), b), and c) that are
essential to the invention, less than 3 wt%, in particular less than 1 wt%, of
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further epoxy group-containing reaction products, based in each case on the
first component made up of the mixture of reactive epoxy resins and optionally
further formulation constituents.
[0045] In a particularly preferred embodiment of this subject, the
mixture of
the epoxy resins is made up of
- a) 10 to 60 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
- b) 15 to 85 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq, and
- c) 0 to 70 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
the quantities of constituents a), b), and c) adding up to 100 wt%.
[0046] In a very particularly preferred embodiment of this subject, the
mixture of the epoxy resins is made up of
- a) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
- b) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq, and
- c) 10 to 40 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
the quantities of constituents a), b), and c) adding up to 100 wt%.
[0047] In a further very particularly preferred embodiment of this
subject,
the mixture of the epoxy resins is made up of
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CA 2788739 2017-09-14
- a) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with polypropylene glycol which has an epoxy equivalent
weight of at least 250 g/eq,
- b) 30 to 45 wt% of an epoxy group-containing reaction product of
epichlorohydrin with a novolac resin which has an epoxy equivalent weight
of at least 175 g/eq and an epoxy functionality of at least 3, and
- c) 10 to 40 wt% of an epoxy group-containing reaction product of
epichlorohydrin with at least one bisphenol which has an epoxy equivalent
weight of at least 500 g/eq,
the quantities of constituents a), b), and c) adding up to 100 wt%.
[0048] It has furthermore proven to be advantageous, in an embodiment of
the present invention, if the second component of the two-component
composition according to the present invention contains, in addition to the
thiol
group-containing hardener, an amine group-containing hardener for epoxy
resins.
[0049] These amine group-containing hardeners for epoxy resins can be
selected, for example, from the following compounds: cyclic tertiary amines
such as, for example, 1,5-diazabicyclo[4.3.]non-5-ene (DBN) or 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU), aromatic amines, and/or mixtures
thereof. The hardeners can be incorporated stoichiometrically into the
hardening reaction, but they can also be catalytically active.
[0050] Adducts of amino compounds with epoxy resins are furthermore
suitable as accelerating additives. Suitable amino compounds are tertiary
aliphatic, aromatic, or cyclic amines. Suitable epoxy compounds are, for
example, polyepoxides based on glycidyl ethers of bisphenol A or F, or of
resorcinol. Concrete examples of such adducts are adducts of tertiary amines
such as 2-dimethylaminoethanol, N-substituted piperazines, N-substituted
homopiperazines, N-substituted aminophenols with di- or polyglycidyl ethers of
bisphenol A or F or of resorcinol.
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[0051] Suitable for this, for example, are the di- or trifunctional
aminoterminated polyalkylene glycols known as "Jeffamine TM D" or
"JeffamineTm T," especially based on ethylene oxide and/or propylene oxide.
Further examples are polyaminoamides (preferably various grades of
Versamid TM, Aradur TM , or AncamideTm), polyamines
(preferably
diethylenetriamine, triethylenetetramine,
tetraethylenepentaamine,
pentaethylenehexamine, AradurTM, AncaminTM, LaurominTm), cycloaliphatic
polyamines (preferably AncamineTM, LauromineTm), polyaminoimidazoline
(preferably VersamidTm), aralkylamines (preferably MXDA), aromatic amines
(preferably 4,4"-diaminodiphenyl sulfone, MDA), tertiary amines (preferably
Versamine EH-30, Versamine EH-50).
[0052] The amino
group-containing hardener or hardeners for epoxy resins
are contained in the agents according to the present invention by preference
in
quantities from 0 to 20 wt%, based on the second component made up of
hardeners and optionally further formulation constituents.
[0053] In a
preferred embodiment, the tertiary amines in particular have
proven to be particularly advantageous. They are contained in the agents
according to the present invention by preference in a quantity from 0 to
20 wt%, in particular in quantities from 0.1 to 18 wt%, very particularly
preferably in quantities from 5 to 15 wt%, based in each case on the second
component made up of hardeners and optionally further formulation
constituents.
[0054] Compositions whose second component contains or represents a
hardener for epoxy resins that is effective in a temperature range from 0 to
60 C, in particular from 0 to 25 C, are particularly preferred according to
the
present invention.
[0055] In order to
improve fracture behavior, in particular at temperatures
below 0 C, the preparations according to the present invention can contain one
or more different so-called toughness improvers or "tougheners." Such
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tougheners are known to those skilled in the art of epoxy adhesives. They can
be selected, for example, from: thermoplastic isocyanates or polyurethanes,
rubber particles, in particular those having a core-shell structure, and block
copolymers, in particular those that contain a first polymer block having a
glass
transition temperature of less than 15 C and a second polymer block having a
glass transition temperature of more than 25 C. Such block copolymers are by
preference selected from those in which a first polymer block is selected from
a
polybutadiene or polyisoprene block, and a second polymer block is selected
from a polystyrene or polymethyl methacrylate block. Specific examples
thereof are block copolymers having the following block structure: styrene-
butadiene-(meth)acrylate, styrene-butad iene-(meth)acrylic acid
esters,
ethylene-(meth)acrylic acid ester-glycidyl (meth)acrylic acid ester, ethylene-
(meth)acrylic acid ester-maleic acid anhydride, methyl methacrylate-butyl
acrylate-methyl methacrylate.
[0056] It has
furthermore proven advantageous according to the present
invention if the first component of the compositions according to the present
invention contains, in addition to the mixture of epoxy resins, at least one
inorganic and/or organic filler.
[0057] In a
further embodiment, it has proven advantageous if the second
component of the composition according to the present invention contains, in
addition to the hardeners that are essential to the invention, at least one
inorganic and/or inorganic filler.
[0058] Fillers
preferred according to the present invention are, for example,
the various ground or precipitated chalks, carbon black, calcium-magnesium
carbonates, talc, barite, and in particular silicate fillers of the aluminum-
magnesium-calcium silicate type, for example wollastonite, chlorite. It may
furthermore be preferred to use calcium sulfate as a filler.
[0059] For weight
reduction, the preparation can also contain, in addition to
the aforesaid "normal" fillers, so-called lightweight fillers. These can be
CA 2788739 2017-09-14
selected from the group of the hollow metal spheres such as, for example,
hollow steel spheres, hollow glass spheres, fly ash (fillite), hollow plastic
spheres based on phenol resins, epoxy resins, or polyesters, expanded hollow
microspheres having a wall material made of (meth)acrylic acid ester
copolymers, polystyrene, styrene/(meth)acrylate copolymers, and in particular
of polyvinylidene chloride as well as copolymers of vinylidene chloride with
acrylonitrile and/or (meth)acrylic acid esters, ceramic hollow spheres, or
organic lightweight fillers of natural origin such as ground nut shells, for
example the shells of cashew nuts, coconuts, or peanuts, as well as cork flour
or coke powder. Particularly preferred in this context are those lightweight
fillers, based on hollow microspheres, that ensure high compressive strength
in
the cured preparation.
[0060] The formulations according to the present invention can in
principle
be formulated to be free of fillers. In the context of this embodiment, the
term
"free of" is to be understood as a filler content of less than 0.5 wt%, by
preference less than 0.1 wt%, based in each case on all formulation
constituents of the respective component.
[0061] In the case of formulations that are liquid at room temperature, a
filler content from 0 to 65 wt%, by preference from 20 to 40 wt%, based in
each
case on all formulation constituents of the respective component, has proven
particularly advantageous.
[0062] In the case of formulations that are solid at room temperature, a
filler
content from 25 to 95 wt%, by preference from 40 to 75 wt%, based in each
case on all formulation constituents of the respective component, has proven
particularly advantageous.
[0063] In addition, the curable preparations according to the present
invention can contain further usual adjuvants and additives such as, for
example, plasticizers, rheology adjuvants, wetting agents, adhesion promoters,
aging protection agents, stabilizers, and/or color pigments.
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[0064] The two-component adhesives according to the present invention
can be used as adhesives, or as a matrix for a composite, a further
embodiment of the present invention being constituted thereby. The adhesive
can be utilized in particular for joining and repairing parts in shipbuilding,
aircraft construction, and vehicle construction. It is notable for good
processability and high strength on the one hand, and particularly low health
risk on the other. Further areas of application for the systems according to
the
present invention are the do-it-yourself sector, as well as the maintenance,
repair, and overhaul sector for vehicles, machines, and aviation, but areas of
application in other sectors of general industry are also encompassed
according to the present invention.
[0065] The agents according to the present invention are made up of two
components. These must be stored separately from one another until
immediately before utilization.
[0066] This can preferably be done by packaging in separate containers.
Removal of the preparation can then be accomplished immediately before
utilization. This can be accomplished by manually measuring out the requisite
quantities from storage vessels, for example drums.
[0067] In addition to purely manual measuring, dispensing can also be
accomplished using simple manual dispensing units or even fully automated
systems. Such systems are marketed, for example, by the Loctite company.
Examples of such automated systems are volumetric double gear pumps,
double precision piston dispensers, double screw pump dispensers, or drum
pump systems.
[0068] In a particularly preferred embodiment of the present invention,
the
preparation according to the present invention are offered in corresponding
cartridges having a volume ratio of 1 : 1, 1 : 2, or 1 : 10 (component having
epoxy resin mixture: component having thiol group-containing hardeners). The
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selection of such double cartridges is intended, according to the present
invention, to ensure consistent dispensing and thus a constant mixing ratio
between the two components. The cartridges according to the present
invention can be emptied, upon utilization, with the aid of simple manual
dispensing units, but also using pneumatic and/or completely automated
systems.
[0069] A second subject of the present invention is therefore a
dispensing
system that comprises two separate containers which, separately from one
another, contain the first and the second component of the compositions
according to the present invention, as well as a dispensing apparatus.
[0070] In another packaging form, the two components of the composition
according to the present invention can be coextruded and accordingly
manufactured so as to be present directly next to one another until
utilization.
The two components must then be thoroughly mixed with one another at the
time of utilization. This can be accomplished, for example, by kneading the
coextrudates.
[0071] A third subject of the present invention is therefore a
composition
according to one of Claims 1 to 9 that is presented as a coextrudate.
[0072] In the context of this embodiment, it has proven to be
advantageous
if one or both components of the coextrudate have small quantities of a dye
added to them. The different coloring of the components of the coextrudate
makes it possible to track the degree of intermixing of the two components of
the coextrudate.
[0073] A fourth subject of the present invention is a method for joining
and/or repairing parts, in which method, in a first step, the two components
of
the compositions according to the present invention are mixed with one
another, the resulting utilization mixture is applied onto the overlapping
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surfaces of the parts to be joined, the parts are then brought into contact
with
one another, and the utilization mixture then cures.
[0074] The curing time depends, in this context, on the exact composition
of
the system, the quantity applied, and the layer thickness, and can be between
a few minutes and several days.
EXEMPLIFYING EMBODIMENTS
Resin mixtures
1.1 Producing the resin mixtures
[0075] The following resin mixtures were produced by mixing the
individual
components and stirring vigorously at 70 to 100 C for 1 hour.
1.2 Measuring viscosities
[0076] Viscosities were measured on an ARES unit of the TA Instruments
company, New Castle, DE 19720, USA, at a temperature of 25 C, and
evaluated using TA Orchestrator software. At a viscosity < 0.25 Pa*s,
measurement was performed using a cone and plate (0.04 /25 mm) at a shear
rate of 0 to 100/s. Viscosities > 0.25 Pa*s and < 10,000 Pa*s were measured
using parallel plates (25 mm/25 mm) at a shear rate of 0 to 100/s. Viscosities
>
10,000 Pa*s were measured using parallel plates (25 mm/25 mm) and at an
angular frequency of 100 rad/s.
[0077] 1.3 Compositions and results
DER 732 DEN 439 Epikote Viscosity EEW*
[g] [g] 1002 [Pa*s] [g/eq]
[9]
H1 40 40 20 80 281
H2 40 30 30 106 311
H3 40 20 40 180 348
H4 40 10 50 320 395
H5 30 40 30 680 294
Ni 20 0 80 20,000 532
N2 15 0 85 75,000 555
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N3 85 0 15 0.375 345
[0078] The EEW* value indicated in the last column was calculated from
the
weighted EEW values of the individual components. As compared with resin
mixtures H1 to H5 according to the present invention, resin mixtures N1 and
N2 not according to the present invention exhibit viscosities that are much
too
high. Optimum utilization is not possible at such viscosities.
2 Determining tensile shear strengths
[0079] To determine the tensile shear strengths, components I and ll as
indicated in Table 2 were thoroughly mixed with one another. Immediately
thereafter, two sandblasted, cold-rolled steel specimens with an overlap area
of 2.5 cm2 were wetted with the resulting adhesive at a layer thickness of 0.2
mm, and bonded. The specimens were then cured for 7 days at room
temperature.
[0080] After that time, the tensile shear strength of the adhesive was
tested
in accordance with DIN EN 1465 at a speed of 15 mm/min.
[0081] Table 2:
Component I Component II Eq Cu/ LSS
Resin Fillers Hardener Catalyst Eq CI I
[N/mnril
3.13 g
2.09 g Luzenac 2;
4.48 g H1 Capcure 3830-
0.30 g Cabosil TS- 1.6 15
(0.0159 Eq) 81
720
(0.0100 Eq)
1.56 g Omyacarb 3.0 g
4.94 g H1 0.37 g
4HD; 0.13 g Capcure 3-800 1.6 12
(0.0176 Eq) Versamine EH-30
Cabosil TS-720 (0.0108 Eq)
5.9 g
10.0 g H5 0.74 g
Capcure 3-800 1.6 12
(0.0340 Eq) Versamine EH-30
(0.0212 Eq)
3.67 g
5.96 g H1 0.37 g
Capcure 3-800 1.6 16
(0.0212 Eq) Versamine EH-30
(0.0132 Eq)
10.0 g H3 5.0g 0.64g 1.6 15
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(0.0287 Eq) Capcure 3-800 Versamine EH-30
(0.0180 Eq)
5.6g
10.09 H2 0.70 g
Capcure 3-800 1.6 12
(0.0322 Eq) Versamine EH-30
(0.0201 Eq)
4.4 g
10.0 g H4 0.559
Capcure 3-800 1.6 16
(0.0253 Eq) Versamine EH-30
(0.0158 Eq)
2.34g
7.42 g N2 0.23 g
Capcure 3-800 1.6 <0.1
(0.0138 Eq) Versamine EH-30
(0.0084 Eq)
3.23g
6.45 g N3 0.32 g
Capcure 3-800 1.6 2
(0.0187 Eq) Versamine EH-30
(0.0116 Eq)
2.41 g
7.42 g Ni 0.24 g
Capcure 3-800 1.6 <0.1
(0.0139 Eq) Versamine EH-30
(0.0087 Eq)
4.90 g DER 4.54 g
0.56 g
331 Capcure 3-800 1.6 11
Versamine EH-30
(0.0262 Eq) (0.0163 Eq)
[0082] In determining the quantities of raw materials caused to react
with
one another, care was taken to maintain a constant ratio between reactive
epoxy components and reactive thiol groups in the utilization mixture. The
respective equivalents used, and their ratios, are likewise evident from Table
2.
[0083] The measured tensile shear strengths (LLS) clearly show that the
two-component compositions according to the present invention having resins
H1 to H3 are clearly superior to the two-component compositions not according
to the present invention having resins N1 to N3. It was additionally possible
to
show by way of these measurements that the tensile shear strengths of the
systems according to the present invention in fact turn out to be higher than
the
tensile shear strength of a conventional adhesive based on DER 331, which
has a high sensitizing potential and is subject to labeling requirements.
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[0084] In a further
embodiment of the Examples, the fillers Luzenac 2,
Cabosil TS-720, and Omyacarb 4HD associated with component I in the
context of the Examples were also incorporated into components II.
3 List of raw materials used
[0085] Cabosil TS-720 Silicon dioxide, pyrogenic amorphous silicic acid;
manufacturer: Cabot
Capcure 3-800 Mercaptan-terminated liquid polymer; mercaptan number
at least 3.0 meq/g; mercaptans equivalent weight 278
g/eq.; manufacturer: Cognis
Capcuree 3830-81 Mixture of 8 parts by weight Capcure 3-800 and 1 part by
weight Versamine EH-30; manufacturer: Cognis
DEN 439 Reaction product of epichlorohydrin
with a
phenol/formaldehyde novolac; EEW 200g/eq; epoxy
functionality 3.8; manufacturer: Dow
DER 331 Reaction product of bisphenol A with epichlorohydrin;
EEW 187 g/eq; manufacturer: Dow
DER 732 Reaction product of epichlorohydrin with polypropylene
glycol; EEW 320 g/eq; manufacturer: Dow
Epikote 1002 Reaction product of epichlorohydrin with bisphenol A;
EEW 638 g/eq; manufacturer: Hexion;
Luzenac 2 Natural association of talc, chlorite, and dolomite;
manufacturer: Luzenac Group
Omyacarb 4HD Calcium carbonate (limestone flour; manufacturer: Onnya
GmbH
Versamine EH-30 2,4,6-Tris(dimethylaminomethyl)phenol; 100%
active
substance content; manufacturer: Cognis.
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