U.S. patent application number 14/123614 was filed with the patent office on 2014-05-08 for vulcanization composition for unsaturated polymers.
This patent application is currently assigned to MLPC INTERNATIONAL. The applicant listed for this patent is Thierry Aubert, Pierre Lugez, Isabelle Yarzabel. Invention is credited to Thierry Aubert, Pierre Lugez, Isabelle Yarzabel.
Application Number | 20140128538 14/123614 |
Document ID | / |
Family ID | 46420427 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140128538 |
Kind Code |
A1 |
Yarzabel; Isabelle ; et
al. |
May 8, 2014 |
VULCANIZATION COMPOSITION FOR UNSATURATED POLYMERS
Abstract
The present invention relates to the field of the vulcanization
of unsaturated polymers, in particular unsaturated halogenated
polymers and more particularly unsaturated chlorinated polymers,
such as, for example, polychloroprene, by using, as vulcanization
agent, a mixture of bis(2,5-dimercapto-1,3,4-thiadiazole) and at
least one organic base. The present invention relates to the
process for the vulcanization of the said polymers with the said
vulcanization mixture.
Inventors: |
Yarzabel; Isabelle; (Herm,
FR) ; Aubert; Thierry; (Lescar, FR) ; Lugez;
Pierre; (Dax, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yarzabel; Isabelle
Aubert; Thierry
Lugez; Pierre |
Herm
Lescar
Dax |
|
FR
FR
FR |
|
|
Assignee: |
MLPC INTERNATIONAL
ROM-DES-LANDES
FR
|
Family ID: |
46420427 |
Appl. No.: |
14/123614 |
Filed: |
June 5, 2012 |
PCT Filed: |
June 5, 2012 |
PCT NO: |
PCT/FR2012/051249 |
371 Date: |
December 3, 2013 |
Current U.S.
Class: |
524/567 ;
252/182.19; 524/574; 524/575; 525/346 |
Current CPC
Class: |
C08L 11/00 20130101;
C08L 23/16 20130101; C08K 5/47 20130101; C08K 5/0025 20130101; C08L
9/06 20130101; C08J 3/24 20130101; C08K 5/47 20130101; C08F 8/34
20130101; C08K 5/47 20130101; C08K 5/47 20130101; C08J 2309/06
20130101; C08J 2311/00 20130101; C08L 11/00 20130101; C08L 9/00
20130101; C08L 23/283 20130101; C08L 7/00 20130101; C08L 9/06
20130101; C08L 23/283 20130101; C08K 5/47 20130101; C08J 2309/00
20130101; C08K 5/47 20130101 |
Class at
Publication: |
524/567 ;
525/346; 524/575; 524/574; 252/182.19 |
International
Class: |
C08L 23/16 20060101
C08L023/16; C08L 11/00 20060101 C08L011/00; C08L 9/06 20060101
C08L009/06; C08F 8/34 20060101 C08F008/34 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 2011 |
FR |
1154904 |
Claims
1-8. (canceled)
9. A composition for the vulcanization of unsaturated polymers,
comprising a mixture of bis(2,5-dimercapto-1,3,4-thiadiazole) and
at least one organic base.
10. The composition according to claim 9, wherein the at least one
organic base is chosen from nitrogenous organic bases.
11. The composition according to claim 10, wherein the at least one
organic base comprises a guanidine.
12. The composition according to claim 10, wherein the at least one
organic base comprises a substituted guanidine.
13. The composition according to claim 12, wherein the at least one
organic base is a guanidine substituted by one or more aryl
groups.
14. The composition according to claim 12, wherein the at least one
organic base comprises diphenylguanidine.
15. The composition according to claim 9, wherein the
bis(2,5-dimercapto-1,3,4-thiadiazole) to organic base molar ratio
is between 1:99 and 99:1.
16. The composition according to claim 15, wherein the
bis(2,5-dimercapto-1,3,4-thiadiazole) to organic base molar ratio
is between 25:75 and 75:25.
17. The composition according to claim 15, wherein the
bis(2,5-dimercapto-1,3,4-thiadiazole) to organic base molar ratio
is approximately 50:50.
18. A process for the vulcanization of an unsaturated polymer,
comprising: mixing the unsaturated polymer with a mixture of
bis(2,5-dimercapto-1,3,4-thiadiazole) and at least one organic
base, and vulcanizing the unsaturated polymer.
19. The process according to claim 18, wherein mixing the
unsaturated polymer with a mixture of
bis(2,5-dimercapto-1,3,4-thiadiazole) and at least one organic base
further comprises mixing the unsaturated polymer with sulphur
and/or one or more inorganic vulcanization agents.
20. The process according to claim 18, further comprising adding
one or more additives chosen from lubricants, fillers, colourants,
preservatives, antioxidants, heat stabilizers, UV stabilizers, and
vulcanization inhibitors or retardants.
21. The process according to claim 18, wherein the unsaturated
polymer is chosen from natural, artificial or synthetic rubbers,
poly(butadienes), styrene and butadiene copolymers (SBRs),
acrylonitrile and butadiene copolymers (NBRs),
ethylene/propylene/diene copolymers (EPDMs), butyl rubbers,
poly(styrene-butadiene styrene) copolymers (SBSs), halogenated
polyalkadienes, and mixtures thereof.
22. The process according to claim 21, wherein the unsaturated
polymer comprises a chlorinated polyalkadiene.
23. The process according to claim 21, wherein the unsaturated
polymer is chosen from chioroprene rubbers or polychloroprenes,
chlorinated natural rubbers, chlorinated polyolefins, chlorinated
butyl rubbers, and mixtures thereof
24. The process according to claim 23, wherein the unsaturated
polymer comprises polychioroprene.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the U.S. National Phase application of
PCT International Application No. PCT/FR2012/051249, filed Jun. 6,
2012, and claims priority to French Patent Application No. 1154904,
filed Jun. 6, 2011, the disclosures of which are incorporated by
reference in their entirety for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of the
vulcanization of unsaturated polymers, in particular unsaturated
halogenated polymers, more particularly unsaturated chlorinated
polymers, such as, for example, polychloroprene. The present
invention relates in particular to the vulcanization agents which
are employed in these processes as vulcanization accelerators.
BACKGROUND OF THE INVENTION
[0003] The accelerators used in the vulcanization of unsaturated
polymers, polyolefins or rubbers, in particular halogenated
rubbers, such as polychloroprene, are generally thiourea-based
accelerators which today compose the crosslinking systems for
rubbers having the best performance.
[0004] Ethylene thiourea (ETU) is the reference thiourea used today
for the vulcanization of chlorinated rubbers, in particular
polychloroprene. However, ETU is toxic in itself, classified in
carcinogenic group 2, according to the classification of the
European Union, the IARC (International Agency for Research on
Cancer) and the EPA (Environmental Protection Agency).
[0005] It is consequently necessary to henceforth look for
replacement products which are less toxic, which are more
environmentally friendly and which exhibit an effectiveness at
least as good as that of thiourea-based accelerators, in particular
ETU, in vulcanization processes.
[0006] The literature already provides some examples of
vulcanization agents or vulcanization accelerators other than
thiourea derivatives. For example, Patent U.S. Pat. No. 4,288,576
describes the use of 2,5-dimercapto-1,3,4-thiadiazole for the
vulcanization of saturated chlorinated polymers, in the presence of
a basic compound chosen from amines, amine salts, quaternary
ammonium salts, aromatic guanidines and the condensation products
of aniline with an aldehyde.
[0007] As other examples, Patent U.S. Pat. No. 5,391,621 describes
the use of certain organopolysulphide compounds derived from
1,3,4-thiadiazole as agents for the vulcanization of chlorinated
polymers. Other polysulphides,
poly[2,5-bis(polysulphano)-1,3,4-thiadiazoles], are described
in
[0008] Patent U.S. Pat. No. 5,563,240, where they are of use as
agents for the vulcanization of polychloroprene.
[0009] Patent Application EP 0 796 890 describes the vulcanization
of halogenated acrylic rubbers in the presence of
2,5-dimercapto-1,3,4-thiadiazole or derivatives and of a metal
dialkyldithiocarbamate.
[0010] More recently, Patent Application US 2003/153652 also
presents compositions for vulcanizing chlorinated polymers, the
said compositions resulting from the mixing of a zeolite compound
with a vulcanization agent chosen from mercaptotriazines,
thiadiazoles and thiurams.
[0011] The publication "An improved curing system for
chlorine-containing polymers", by R. F. Ohm and T. C. Taylor (which
appeared in "Rubber World", March 1997, pages 33 to 38), presents a
comparative study between ETU and DMTD
(2,5-dimercapto-1,3,4-thiadiazole), which are used as agents for
the vulcanization of polychloroprene in combination with
vulcanization activators.
[0012] Despite these solutions already put forward for the
replacement of ETU, a need remains, however, for vulcanization
compositions which are even more effective, in particular for the
vulcanization of unsaturated polymers, especially of unsaturated
halogenated polymers and more particularly of unsaturated
chlorinated polymers, more environmentally friendly and capable of
conferring, on the vulcanized polymers, mechanical properties and
properties of resistance to ageing which are further improved.
SUMMARY OF THE INVENTION
[0013] A first objective of the present invention consists in
providing an agent (or accelerator) for the vulcanization of
unsaturated polymers, in particular of polyalkadienes, more
particularly of unsaturated halogenated polymers, typically of
unsaturated chlorinated polymers and in particular polychloroprene,
the said agent or accelerator advantageously having to be nontoxic
or only very slightly toxic and more environmentally friendly.
[0014] Another objective of the present invention consists in
providing a vulcanization accelerator which is less toxic than ETU
and in particular which does not release compounds of nitrosamine
type.
[0015] Yet another objective consists in providing a vulcanization
agent which confers, on the unsaturated polymers, in particular
unsaturated halogenated polymers, for example unsaturated
chlorinated polymers, in particular of polychloroprene type,
mechanical properties equivalent to those obtained with systems
employing toxic accelerators.
[0016] As another objective of the present invention, the
vulcanization agent provided can confer good ageing properties on
the polymers. In addition, an objective also consists in providing
a vulcanization accelerator which makes it possible to increase the
scorch time (or prevulcanization time).
[0017] Yet another objective consists in reducing the amount of
inorganic vulcanization agents, generally metal oxides, in
particular zinc and/or magnesium oxides, used in the vulcanization
of unsaturated polymers, in particular unsaturated halogenated
polymers, more specifically unsaturated chlorinated polymers,
without affecting the mechanical, rheological and other properties
thereof, thus making it possible to also reduce the amount of toxic
effluents associated with the process, while also reducing the
production costs.
[0018] The Applicant Company has now discovered that the
abovementioned objectives can be achieved in all, or at least in
part, by virtue of the use of the vulcanization accelerator which
is a subject-matter of the invention which will be described in
detail below.
BRIEF DESCRIPTION OF THE DRAWING
[0019] FIG. 1 is a graph of the change in torque as a function of
time for mixtures containing vulcanization formulations.
DETAILED DESCRIPTION OF THE INVENTION
[0020] According to a first aspect, the invention relates to the
use, as agent for the vulcanization of unsaturated polymers, in
particular unsaturated halogenated polymers, more particularly
unsaturated chlorinated polymers, of at least one mixture
comprising bis(2,5-dimercapto-1,3,4-thiadiazole), denoted bis-DMTD
in the continuation of the present description, and at least one
organic base.
[0021] bis-DMTD corresponds to one of the two following structures,
depending on the tautomeric forms selected:
##STR00001##
[0022] The process for the manufacture of bis-DMTD has been known
for many years and is, for example, described in Patent Application
CN-A-101096366. A process for the preparation of bis-DMTD which is
even more environmentally friendly has recently been described in
Patent Application EP-A-2 272 836.
[0023] bis-DMTD is today mainly used in lubricant compositions but
is used to a very slight extent in compositions comprising natural,
artificial or synthetic rubbers, where it generally acts as
preservative and has never been described as such as an additive
for the vulcanization of unsaturated polymers. bis-DMTD does not
generate nitrosamines.
[0024] The organic base used in combination (mixture) with the
bis-DMTD can be of any type known to a person skilled in the art.
However, preference is given to nitrogenous organic bases and more
particularly guanidines, which are optionally substituted, with
which an entirely unexpected effect of improving the kinetics of
vulcanization and the scorch time has been observed, when they are
used in combination with bis-DMTD.
[0025] Entirely noteworthy results have been obtained with
guanidines substituted by one or more aryl groups, preferably by
one or two aryl groups, preferably by two aryl groups. An organic
base which is altogether preferred in the context of the present
invention is diphenylguanidine.
[0026] As a general rule, the bis-DMTD/organic amine molar ratio is
between 1:99 and 99:1, preferably between 25:75 and 75:25, for
example approximately 50:50.
[0027] According to an alternative form of the invention,
preference is given to a vulcanization composition in which the
bis-DMTD/organic amine molar ratio is between 40:60 and 99:1,
preferably between 50:50 and 99:1, more preferably between 60:40
and 99:1, entirely preferably between 70:30 and 99:1.
[0028] The polymers which can advantageously be vulcanized by
virtue of the abovementioned mixture are unsaturated polymers, in
particular unsaturated halogenated polymers, more particularly
unsaturated chlorinated polymers. More specifically, the polymers
targeted in the present invention are all the polymers and
copolymers comprising at least one ethylenic unsaturation, among
which may be mentioned, as nonlimiting examples, natural,
artificial or synthetic rubbers, poly(butadienes), styrene and
butadiene copolymers (SBRs), acrylonitrile and butadiene copolymers
(NBRs), ethylene/propylene/diene copolymers (EPDMs), butyl rubbers,
SBSs, halogenated polyalkadienes, in particular chlorinated
polyalkadienes, and others, as well as the mixtures of these
homopolymers and copolymers in all proportions.
[0029] According to a preferred aspect, the chlorinated
polyalkadienes comprise more than 1% by weight of chlorine,
preferably more than 2% by weight of chlorine and more preferably
approximately 5% by weight of chlorine. The chlorine content can
reach up to 40% by weight of chlorine, with respect to the total
weight of the polymer.
[0030] Mention may be made, as examples of such chlorinated
polyalkadienes, without implied limitation, of chloroprene rubbers
or polychloroprenes, chlorinated natural rubbers, chlorinated
polyolefins, chlorinated butyl rubbers and others.
[0031] According to one embodiment of the present invention,
preference is very particularly given to the use of the
abovementioned vulcanization mixture for the vulcanization of
polychloroprene, denoted CR in the continuation.
[0032] Such mixtures can comprise from 10% by weight to 90% by
weight of each of the polymers, preferably from 25% by weight to
75% by weight, with respect to the total weight of the polymers in
the mixtures.
[0033] According to a preferred embodiment, the chlorinated
polymers which can be used in the context of the present invention
are chlorinated polymers comprising one or more ethylenic
unsaturations and, entirely preferably, the chlorinated polymers
targeted in the present invention are polychloroprenes, alone or as
blends with other homopolymers and/or copolymers, as indicated
above.
[0034] The bis-DMTD, in combination with an organic base, in
particular a nitrogenous organic base, more particularly a
guanidine, acts synergistically in the vulcanization of the
unsaturated polymers. bis-DMTD appears to be a good sulphur donor,
which makes it a good vulcanization agent. The amine bases promote,
on the one hand, the release of the sulphur present in the
bis-DMTD, which improves the properties of the vulcanisate, and, on
the other hand, they improve the kinetics of vulcanization, while
maintaining a certain scorch safety.
[0035] According to another embodiment, sulphur can be added to the
vulcanization process employing the vulcanizing composition
according to the present invention. This is because it has been
discovered that the addition of a small amount of sulphur to the
bis-DMTD can catalyse the reaction and thus increase the bridging
density. This makes it possible to obtain a very high degree of
crosslinking, which confers excellent compression set properties
and also very slight swellings in oil of the vulcanized polymer
thus obtained.
[0036] According to yet another embodiment, the bis-DMTD can
additionally be employed on an elastomer support, in order to
promote the dispersion thereof and thus to reduce the mixing
times.
[0037] The use of bis-DMTD, in combination with at least one
organic base, for example a guanidine, as vulcanization accelerator
has proved to be entirely effective during the vulcanization of
polychloroprene. In particular, the kinetics of vulcanization
employing a bis-DMTD/organic base mixture have proven to be
comparable, indeed even superior, to the kinetics of vulcanization
observed in the presence of ETU.
[0038] In addition to rapid kinetics of vulcanization, the use of
the bis-DMTD/organic base mixture in place of ETU as vulcanization
agent makes it possible to confer, on the unsaturated polymers, in
particular unsaturated halogenated polymers, a good tear strength
and a good tensile strength, and also good resistance to
ageing.
[0039] A decrease in the crystallization effect by an increase in
the bridging degree has also been observed. This represents a
considerable advantage when it is known that the crystallization is
a very harmful phenomenon well known to a person skilled in the art
which brings about hardening of the CR-base mixtures, which limits
their lifetime.
[0040] As another advantage, it has likewise been observed that the
scorch time of the unsaturated polymers vulcanized by the
bis-DMTD/organic base mixture can be effectively controlled by
means of retardants appropriate to this novel vulcanization system
(for example MBTS and/or CTPI in polychloroprene).
[0041] According to an embodiment of the present invention, the
bis-DMTD/organic base mixture is advantageously used as
accelerating agent for the vulcanization of chlorinated polymers,
in combination with one or more inorganic vulcanization agents well
known to a person skilled in the art. According to a preferred
aspect, the inorganic vulcanization agents are chosen from metal
oxides and in particular from zinc oxide (ZnO), magnesium oxide
(MgO) and others, and also the mixtures of two or more of them in
all proportions.
[0042] According to another aspect, the present invention relates
to the process for the vulcanization of an unsaturated polymer, the
said process comprising at least the following stages: [0043]
mixing the said unsaturated polymer with the bis-DMTD/organic base
mixture, optionally sulphur and optionally one or more inorganic
vulcanization agents, as described above, [0044] vulcanizing the
said unsaturated polymer, according to procedures known to a person
skilled in the art, and [0045] recovering the said vulcanized
unsaturated polymer.
[0046] The mixing of the unsaturated polymer with the
bis-DMTD/organic base combination can be carried out according to
any technique known per se, for example as a masterbatch (with
regard to molten polymer, solid polymer, as granules, as chips, and
others) or in paste form (for example with regard to wax or with a
high oil content). The bis-DMTD and the organic base can be added
simultaneously or separately. As indicated above, the bis-DMTD can
be introduced in the supported form, for example supported on an
olefin, in order to reduce the mixing time of the said bis-DMTD
with the polymer to be vulcanized.
[0047] In order to carry out the vulcanization, as a function of
the final properties required, sulphur can be added simultaneously
or before or subsequently to the bis-DMTD/organic base mixture and
simultaneously or before or subsequently to the inorganic agents
(in particular metal oxides). A person skilled in the art, familiar
with the techniques and conditions for the vulcanization of
unsaturated polymers, will know how to adapt the process of the
invention as a function of the nature of the vulcanization agents
and of the polymers which he wishes to vulcanize.
[0048] Thus, the vulcanization is carried out according to any
procedure known to a person skilled in the art, at a temperature,
at a pressure and for a period of time which is appropriate
according to the nature and the type of vulcanization carried
out.
[0049] Various additives can be added during the vulcanization
process according to the present invention. These additives are
well known to a person skilled in the art and can be chosen, as
nonlimiting examples, from lubricants, fillers, colourants,
preservatives, antioxidants, heat stabilizers, UV stabilizers,
vulcanization inhibitors or retardants, such as MBTS
(mercaptobenzothiazole disulphide), CTPI
(N-cyclohexylthiophthalimide), and others.
[0050] According to a preferred alternative form of the process of
the present invention, the vulcanization can be carried out by
simultaneously adding a mixture of the vulcanization agents, in or
not in combination with the covulcanization agents and other
additives. Such a mixture ("mixture for vulcanization") can thus
comprise one or more of the following ingredients, which will be
premetered according to the nature of the chlorinated polymer and
the degree of vulcanization thereof desired: sulphur, bis-DMTD,
organic base, inorganic agents and additive(s).
[0051] The present invention is now illustrated by means of the
examples which follow and which do not have any limiting aim from
the viewpoint of the scope of the present invention, which is
defined by the appended claims.
EXAMPLES
Example 1
Polychloroprene (CR) Vulcanization Test
[0052] All the mixtures are prepared in a 2.5 1 Repiquet internal
mixer with a stirring speed of 50 revolutions/min and a filling
coefficient of 1.4. The CR base used exhibits the following
composition (denoted "CR A base" in the continuation), in which the
parts are expressed by weight:
TABLE-US-00001 CR A base - Materials Parts Neoprene WRT 100 N550
(carbon black) 50 Kaolin grade B 20 DINP (phthalate oil) 20
Elastomag .RTM. 170 (MgO) 4 Stearin 0.5 Total 194.5
[0053] The mercaptan-grade neoprene WRT is generally vulcanized in
the presence of ETU, used as vulcanization accelerator, which
confers the best results in terms of compression set (CS) and
ageing. As indicated above, ETU is a toxic product due to its
chemical nature and exhibits risks when used: ETU is regarded as
carcinogenic by ingestion, mutagenic or also as exhibiting risks of
sterility by simple contact with the skin.
[0054] The present study shows that ETU can be advantageously
replaced by the vulcanization mixture according to the invention.
This study is carried out using an appropriate 3.times.3
experimental plan. This experimental plan makes it possible to
simultaneously vary three parameters over three levels by using the
symmetry conditions of a cube. For this plan, the working
hypotheses are as follows: [0055] linear incrementation in the
variables X1, X2 and X3; [0056] variation in the calculation values
from -1 to +1 (methods); [0057] necessary changes in variables:
experimental parameters towards the calculation variables, for the
interpretation of the results; [0058] no taking into account of the
cross interactions: X1X2, X1X3, X2X3; [0059] no equidistances
between the values; [0060] accuracy of 10 to 15%; [0061]
second-degree equations.
[0062] This experimental plan makes it possible to obtain the
change in the properties with 9 mixtures instead of 27. The
following parameters were used: [0063] X1: bis-DMTD: 0.5/0.75/1
(proportions by weight) [0064] X2: DPG: 0.1/0.2/0.3 (proportions by
weight) [0065] X3: sulphur: 0/0.25/0.5 (proportions by weight)
[0066] The respective proportions by weight (parts by weight) of
the variables X1, X2 and X3 for the 9 tests (formulations F1 to F9)
are collated in the following Table 1, in which the bis-DMTD is in
the powder form (sold by MLPC International), the DPG is
Mixland.RTM.+DPG 80 GA F140 (sold by MLPC International), and the
sulphur is Mixland.RTM.+SM300 80 GA F140 (sold by MLPC
International):
TABLE-US-00002 TABLE 1 F1 F2 F3 F4 F5 F6 F7 F8 F9 bis-DMTD 0.5 0.75
1 1 0.5 0.75 0.75 1 0.5 DPG 0.1 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.3
Sulphur 0 0.25 0.5 0 0.25 0.5 0 0.25 0.5
[0067] These 9 formulations are used to prepare 9 mixtures M1 to M9
respectively, with 194.5 parts by weight of the CR A base, 5 parts
by weight of Mixland.RTM.+ZnO 90 GA F100 (zinc oxide, ZnO, sold by
MLPC International), 1 part by weight of paraffin and 1 part by
weight of antioxidant Ekaland.RTM. 100, sold by MLPC International.
A control mixture, denoted MO, devoid of sulphur, is similarly
prepared with 194.5 parts by weight of the CR A base and 0.75 part
by weight of ETU, instead of the bis-DMTD +DPG mixture.
[0068] The mixtures are prepared so as to obtain a blank weighing
approximately 600 g, corresponding to 2 plaques with a thickness of
2 mm, and the production of the CS graphs. Vulcanization is carried
out to T.sub.90 (vulcanization time for obtaining 90% of the
maximum torque) at 170.degree. C.
[0069] The mixtures M1 to M9 and M0 are characterized mechanically
(rheometric study). The change in the torque as a function of time,
at a temperature of 170.degree. C., is shown in FIG. 1. It is
noticed that the mixtures M2 to M9 according to the invention
exhibit a greater torque than that of the control mixture M0, where
the vulcanization agent used is ETU.
[0070] The mixtures M1 to M9 are characterized mechanically and the
data collected are used in the matrix of the experimental plan,
which makes it possible to obtain a theoretical change in the
properties of the mixtures vulcanized with bis-DMTD. The
experimental plan makes it possible to obtain a change in 3D of the
properties.
[0071] From this experimental plan, it can be accepted that DPG has
a synergistic effect with the bis-DMTD, favouring the release of
the sulphur atoms present in the bis-DMTD and thus improving the
final properties of the material. It can also be deduced that the
sulphur acts as catalyst of the reaction.
[0072] In conclusion, at the end of this experimental plan, two
formulae can be selected as a function of the specifications to be
achieved: [0073] the mixture M7, which gives excellent results in
ageing, better than with the ETU-base control formula MO; [0074] an
optimized mixture M10 (cf. Table 2), the composition of which was
deduced from the experimental plan and which gives better results
than with ETU at 70.degree. C., in CS and in terms of swelling with
oil.
TABLE-US-00003 [0074] TABLE 2 M0 M7 M10 CR A base 194.5 194.5 194.5
Ekaland .RTM. + 100 (antioxidant) 1 1 1 Paraffin 1 1 1 Mixland
.RTM. + ZnO 90 GA F100 5 5 5 Mixland .RTM. + ETU 80 GA F140 0.75 --
-- bis-DMTD powder (MLPC International) -- 0.75 0.5 Mixland .RTM. +
SM300 80 GA F140 -- 0.3 0.25 Mixland .RTM. + DPG 80 GA F140 -- --
0.2 Rheometry on an MDR at 170.degree. C. - according to Standard
NFT 46-006 (or ISO 6502) C.sub.max-C.sub.min (dN m) 14.1 14.6 --
t.sub.s 1 (min) 1.1 0.82 -- t.sub.c 90 (min) 12.3 15.2 -- Scorch
time on a Mooney viscometer at 125.degree. C. - according to
Standard NFT 43-004 (or ISO 289-2) MS t3 9.25 6.1 -- MS t10 13.3
10.5 -- MS t18 24.3 14.8 -- Dynamometric properties - according to
Standard NFT 46-002 (or ISO 37) TS: Tensile strength (MPa) 17 17
17.5 Eb: Elongation at break (%) 360 437 438 M100: Modulus at 100%
(MPa) 3.9 3.9 3.8 M200: Modulus at 200% (MPa) 8.5 7.9 7.9 M300:
Modulus at 300% (MPa) 14.1 12.2 12.6 Tearing (kN/m) according to
Standard 41 44 44 NFT 46-033 (or ISO 34-2) Shore A hardness
according to 67 67 64 Standard NFT 46-052 (or ISO 868) M0 M7 M10
Ageing, air, 72 hours, at 100.degree. C. - according to Standard
NFT 46-004 (or ISO 188) TS (MPa) 16.8 -1.4% 16.9 -0.7% 17.4 -1.0%
Eb (%) 298 -17.3% 329 -24.6% 354 -19.1% M100 (MPa) 5.3 36.3% 5.6
44.5% 5.5 43.3% M200 (MPa) 11.5 30.1% 10.9 37.9% 10.7 36.5% M300
(MPa) -- -- 15.7 28.3% 15.5 23.8% Ageing, air, 7 days, 100.degree.
C. - according to Standard NFT 46-004 (or ISO 188) TS (MPa) 17
-0.1% 16.3 -3.9% -- -- Eb (%) 275 -23.5% 293 -32.8% -- -- M100
(MPa) 6.3 62.3% 6.3 61.6% -- -- M200 (MPa) 12.8 50.3% 12 52.0% --
-- Ageing, air, 10 days, 100.degree. C. - according to Standard NFT
46-004 (or ISO 188) TS (MPa) 18 5.1% 16.4 -3.2% -- -- Eb (%) 273
-24.1% 291 -33.3% -- -- M100 (MPa) 7.2 85.0% 6.5 66.0% -- -- M200
(MPa) 13.7 61.0% 12.2 55.3% -- -- Ageing, air, 72 hours, at
70.degree. C. - according to Standard NFT 46-004 (or ISO 188) M0 M7
M10 Swelling in oil (%) ISO R1817 39.3 40.6 32.8 CS at 25% (%)*
21.5 21.4 11.7 *according to standard NFT 46-011 (or ISO 815)
[0075] The coupling of bis-DMTD with an organic base (in this case,
a guanidine, DPG), with or without the use of sulphur as catalyst,
meets the environmental requirements by providing an unclassified
system and not producing nitrosamines, while guaranteeing, to the
users, the final properties expected for a polychloroprene
mixture.
[0076] In addition, this bis-DMTD/organic base (in the example,
DPG) mixture makes it possible to reduce the content of ZnO
necessary, without affecting the properties of the final product.
In point of fact, reducing the metal oxides is one of the major
ways of improving the environmental impact. The coupling provided
in the present invention, due to the reduction in the content of
ZnO, thus contributes to new environmental regulations.
[0077] Two mixtures are prepared from the mixture M7, which
mixtures are denoted M7-2 and M7+2 and in which the zinc oxide
contents are respectively -2 parts and +2 parts, with respect to
the 5 parts present in the mixture M7. The results obtained with
use of metal oxides are presented in the following Table 3:
TABLE-US-00004 TABLE 3 M0 M7 M7 - 2 M7 + 2 CR A base 194.5 194.5
194.5 194.5 Ekaland .RTM. 100 1 1 1 1 Paraffin 1 1 1 1 Mixland
.RTM. + ZnO 90 GA F100 5 5 3 7 Mixland .RTM. + ETU 80 GA F140 0.75
Ekaland .RTM. bis-DMTD 0.75 0.75 0.5 Mixland .RTM. + DPG 80 GA F140
0.2 0.2 0.2 Rheometry on an MDR at 170.degree. C. - according to
Standard NFT 46-006 (or ISO 6502) C.sub.max-C.sub.min (dN m) 14.1
14.6 14 14.25 t.sub.s 1 (min) 1.1 0.76 0.77 0.76 t.sub.c 90 (min)
12.3 14.2 14 14.2 Scorch time on a Mooney viscometer at 125.degree.
C. according to Standard NFT 43-004 (or ISO 289-2) MS t3 9.7 6.1
5.9 6 MS t10 13.3 10.5 10.5 10.5 MS t18 24.3 14.8 15.2 14.9
[0078] Tests were also carried out in order to measure the
influence of certain known retardants used to increase the scorch
time. The retardants tested here are MBTS (mercaptobenzothiazole
disulphide) and CTPI (N-cyclohexylthiophthalimide). The mixtures
M11 and M12 were prepared and tested. The compositions of the
mixtures M11 and M12, and their performances, with respect to the
mixtures M0 and M7, are presented in the following Table 4:
TABLE-US-00005 TABLE 4 M0 M7 M11 M12 CR A base 194.5 194.5 194.5
194.5 Ekaland .RTM. 100 1 1 1 1 Paraffin 1 1 1 1 Mixland .RTM. +
ZnO 90 GA F100 5 5 5 5 Mixland .RTM. + ETU 80 GA F140 0.75 -- -- --
bis-DMTD powder (MLPC 0.75 0.75 0.75 International) Mixland .RTM. +
SM300 80 GA F140 -- -- -- 0.5 Mixland .RTM. + DPG 80 GA F140 -- 0.2
0.2 0.2 Mixland .RTM. + CTPI 80 GA F500 -- -- -- 1 Mixland .RTM. +
MBTS 80 GA F140 -- -- 2 -- Rheometry on an MDR at 170.degree. C. -
according to Standard NFT 46-006 (or ISO 6502) C.sub.max-C.sub.min
(dN m) 14.1 14.6 12.6 15.7 t.sub.s 1 (min) 1.1 0.76 0.8 0.9 t.sub.c
90 (min) 12.3 14.2 9 9.8 Scorch time on a Mooney viscometer at
125.degree. C. according to Standard NFT 43-004 (or ISO 289-2) MS
t3 9.7 6.1 8.5 9.1 MS t10 13.3 10.5 13.1 14.5 MS t18 24.3 14.8 16.4
18.1
Example 2
Styrene/Butadiene Rubber (SBR) Vulcanization Test
[0079] As for Example 1 above, the mixing of components is carried
out in a 2.5 l Repiquet internal mixer at 50 revolutions/min with a
filling coefficient of 1.4.
[0080] An "SBR base" is thus prepared, for which the natures and
amounts of materials introduced into the mixer are as follows (the
parts are expressed by weight):
TABLE-US-00006 Materials Parts SBR 1502 100 N220 (carbon black) 51
Exarol 25 oil 11.5 Total 162.5
[0081] Two formulations S1 and S2 for vulcanization are prepared
which have the characteristics presented in the following Table
5:
TABLE-US-00007 TABLE 5 S1 S2 SBR base 162.5 162.5 Mixland .RTM. +
ZnO 90 GA F100 5 5 Stearic acid 3 3 Ekaland .RTM. DPG c 0 0.5
bis-DMTD powder (MLPC Intl) 0.5 0.5 Mixland .RTM. + SM300 80 GA
F140 2 2 Rheometry on an MDR at 170.degree. C. - according to
Standard NFT 46-006 (or ISO 6502) .DELTA.C (dN m) 9.32 11.35
t.sub.s 1 (min) 2.16 1.72 t.sub.c 90 (min) 23.9 16.3
[0082] The amine compounds (in this instance DPG) act
synergistically with the bis-DMTD: the DPG promotes the release of
sulphur, which increases the bridging degree and improves the
kinetics of vulcanization.
Example 3
EPDM Vulcanization Test
[0083] As for the preceding examples, the mixing is carried out in
a 2.5 l Repiquet internal mixer at 50 revolutions/min and a filling
coefficient of 1.4.
[0084] The "EPDM base" used exhibits the following composition, in
which the parts are expressed by weight:
TABLE-US-00008 Materials Parts EPDM Keltan .RTM. 512x50 150 ZnO,
active 4 Carbon black N550 111 Liquid paraffin 17 Total 282
[0085] The results of tests carried out with 4 formulations denoted
E1, E2, E3 and E4 and prepared from the above EPDM base are
presented in the following Table 6:
TABLE-US-00009 TABLE 6 E1 E2 E3 E4 EPDM base 282 282 282 282
Stearic acid 2 2 2 2 Ekaland .RTM. ZBEC pd 1.4 1.4 1.4 1.4 Mixland
.RTM. + ZDTP 50 GA F500 3 3 3 3 Mixland .RTM. + DPG 80 GA F140 0.5
0 0.5 0.5 bis-DMTD powder (MLPC Intl) 0 0.5 0.5 1 Mixland .RTM. +
SM300 80 GA F140 2 2 2 2 Rheometry on an MDR at 170.degree. C. -
according to Standard NFT 46-006 (or ISO 6502) .DELTA.C (dN m) 10.8
10.6 10.9 11.3 t.sub.s 1 (min) 0.36 0.43 0.39 0.43 t.sub.c 90 (min)
3.38 3.41 3.32 3.28
[0086] On comparing the formulations E1 and E2, it is found that
bis-DMTD is equivalent in rheometry as replacement for DPG with a
better scorch safety. On comparing the formulations E2 and E3, a
synergistic effect is observed between bis-DMTD and DPG: a better
bridging degree and a reduced vulcanization time are obtained,
while maintaining the scorch safety. Finally, on comparing the
results obtained with formulations E3 and E4, it is noted that the
increase in the amount of bis-DMTD further accentuates the
synergistic effect.
* * * * *