U.S. patent application number 12/862116 was filed with the patent office on 2011-07-21 for nano-sized hydrogenated diene-based latex particles.
This patent application is currently assigned to UNIVERSITY OF WATERLOO. Invention is credited to Qinmin Pan, Garry L. Rempel.
Application Number | 20110178231 12/862116 |
Document ID | / |
Family ID | 41478823 |
Filed Date | 2011-07-21 |
United States Patent
Application |
20110178231 |
Kind Code |
A1 |
Pan; Qinmin ; et
al. |
July 21, 2011 |
Nano-sized hydrogenated diene-based latex particles
Abstract
The present invention relates to hydrogenated nano-sized
diene-based latex particles, a method for their production and
their use.
Inventors: |
Pan; Qinmin; (Waterloo,
CA) ; Rempel; Garry L.; (Waterloo, CA) |
Assignee: |
UNIVERSITY OF WATERLOO
Waterloo
CA
|
Family ID: |
41478823 |
Appl. No.: |
12/862116 |
Filed: |
August 24, 2010 |
Current U.S.
Class: |
524/565 |
Current CPC
Class: |
C08L 15/005 20130101;
C08C 19/02 20130101; C08L 9/04 20130101; Y10T 428/2982
20150115 |
Class at
Publication: |
524/565 |
International
Class: |
C08L 9/04 20060101
C08L009/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 26, 2009 |
EP |
09 168 709.5 |
Claims
1. Diene-based hydrogenated polymer latex particles having a
particle size measured as d.sub.90-value of less than 60 nm.
2. Latex particles according to claim 1, wherein the diene-based
latex particles are acrylonitrile-butadiene polymers.
3. Process for the selective hydrogenation of diene-based
unsaturated polymer particles in latex form, comprising a)
providing diene-based unsaturated polymer particles having a
particle size measured as d.sub.90-value of less than 60 nm b)
combining the diene-based unsaturated polymer in latex form with
hydrogen or a hydrogen-source in the presence of c) a transition
metal containing catalyst and preferably d) maintaining a
temperature of from about 35.degree. C. to about 180.degree. C.,
preferably from about 80.degree. C. to about 160.degree. C.
4. Process according to claim 3, wherein the particle size of the
polymer particles measured as d.sub.90-value is less than 20
nm.
5. Process according to claim 3, wherein the metal atom of the
catalyst is a group VIII-B metal of atomic number from 44 to 76
including Ru, Rh, Ir and Os.
6. Process according to claim 3, wherein the metal atom of the
catalyst is rhodium.
7. Process according to claim 3, wherein the catalyst corresponds
to the formula RhQL.sub.x wherein Q is hydrogen or an anion,
preferably a halide and more preferably a chloride or bromide ion
wherein L is a ligand compound of the formula R.sub.mB, wherein R
is a C.sub.1-C.sub.8-alkyl group, a C.sub.4-C.sub.8-cycloalkyl
group a C.sub.6-C.sub.15-aryl group or a C.sub.7-C.sub.15-aralkyl
group, B is phosphorus, arsenic, sulfur, or a sulphoxide group, and
m is 2 or 3, preferably m is 2 when B is sulphur or sulphoxide, and
m is 3 when B is phosphorus or arsenic, and wherein x is 2, 3 or 4,
preferable x is 3 when Q is halogen and preferably x is 4 when Q is
hydrogen.
8. Process according to claim 3, wherein the hydrogenation is
conducted at a temperature of 35 to about 180.degree. C.
9. Process according to claim 3, wherein the hydrogenation is
carried out with essentially pure hydrogen gas at a pressure of 0.1
to about 20 MPa.
10. Process according to claim 3, wherein the unsaturated polymer
is composed of a conjugated diene D, a copolymerizable monomer A
containing a nitrile group and optionally further copolymerizable
monomers C.
11. Process according to claim 3, wherein the unsaturated polymer
is an acrylonitrile/butadiene copolymer.
12. Process according to claim 3, wherein the hydrogenation is
conducted in a batch mode.
13. Process according to claim 3, wherein the hydrogenation is
conducted in a continuous or semi-batch mode.
14. Shaped article comprising a hydrogenated polymer obtained
according to claim 3.
Description
FIELD OF THE INVENTION
[0001] The invention relates to nano-sized hydrogenated diene-based
latex particles, a method for producing such particles and methods
of using them as rubber.
BACKGROUND OF THE INVENTION
[0002] Diene-based unsaturated polymers, for example nitrile
butadiene rubbers, also known as NBR, produced through
polymerization of acrylonitrile and butadiene are well-known in the
art. Processes for copolymerization of acrylonitrile and butadiene
are described for example in U.S. Pat. No. 3,690,349 and U.S. Pat.
No. 5,770,660. Depending on production conditions such polymers can
be obtained as latex in aqueous medium. Unsaturated diene-based
polymers such as NBR are used for a variety of purposes in
industry, moreover processes for hydrogenating such unsaturated
polymers are well-known in the art.
[0003] It has been known that carbon-carbon double bonds in
diene-based polymers may be selectively hydrogenated by treating
the polymer in an organic solution with hydrogen in the presence of
a catalyst to produce their saturated polymers which have
significantly improved end-use properties. Such processes can be
selective in the double bonds which are hydrogenated so that, for
example, the double bonds in aromatic or naphthenic groups are not
hydrogenated and double or triple bonds between carbon and other
atoms such as nitrogen or oxygen are not affected. This field of
art contains many examples of catalysts suitable for such
hydrogenations, including catalysts based on cobalt, nickel,
rhodium, ruthenium, osmium, and iridium. The suitability of the
catalyst depends on the extent of hydrogenation required, the rate
of the hydrogenation reaction and the presence or absence of other
groups, such as carboxyl and nitrile groups, in the polymers.
[0004] Hydrogenation of diene-based polymers has been very
successful, if organometallic catalysts or some special metal salt
catalysts and high-pressure gaseous hydrogen are used. Such success
has been realized in solution hydrogenation, bulk hydrogenation and
direct latex hydrogenation. For the solution hydrogenation of a
diene-based polymer, the polymer is first dissolved in an organic
solvent and then hydrogenation is carried out; after the
hydrogenation, post-treatment is applied to recycle the organic
solvent and to recover the metal catalyst. In this field, there
have been already many patents and patent applications filed in
this area, such as U.S. Pat. No. 6,410,657, U.S. Pat. No.
6,020,439, U.S. Pat. No. 5,705,571, U.S. Pat. No. 5,057,581, and
U.S. Pat. No. 3,454,644.
[0005] In direct latex hydrogenation, a catalyst is directly added
into the latex of a diene-based polymer for the hydrogenation
operation. Many diene based polymers, copolymers or terpolymers are
made by emulsion polymerization processes and they are in a latex
form when they are discharged from polymerization reactors.
Therefore it is very desirable to directly hydrogenate a
diene-based polymer in latex form which is receiving increasing
attention in the recent decade. Many efforts have been made to
realize such a process. U.S. Pat. No. 7,385,010 has disclosed a
process of directly hydrogenating diene-based polymer latex by
using organometallic catalysts and high-pressure gaseous
hydrogen.
[0006] In bulk hydrogenation, a catalyst is directly mixed with a
diene-based polymer or a catalyst is entrapped into the polymer,
and then hydrogenation is applied. U.S. Pat. No. 7,345,115 teaches
a process of using an organometallic catalyst and high-pressure
gaseous hydrogen to hydrogenate bulk diene-based polymers at a
temperature higher than 100.degree. C., in which the polymer is
directly mixed with the catalystasn particles.
[0007] A significant characteristic of the above processes is that
they all involve catalysts in which a noble metal is involved, that
they all require high-pressure hydrogen and that they may need a
relatively long reaction time.
[0008] To avoid using noble metals and avoid being operated under
high-pressure, significant attention has been paid to the
hydrogenation of C.dbd.C bonds using hydrazine or a derivative of
hydrazine as a reducing agent together with an oxidant like oxygen,
air or hydrogen peroxide. The hydrogen source to saturate the
C.dbd.C bonds is then generated in-situ as a result of the redox
reactions in which diimide is also formed as intermediate. In U.S.
Pat. No. 4,452,950 the latex hydrogenation is performed using the
hydrazine hydrate/hydrogen peroxide (or oxygen) redox system to
produce diimide in situ. CuSO.sub.4 or FeSO.sub.4 is used as a
catalyst. U.S. Pat. No. 5,039,737 and U.S. Pat. No. 5,442,009
provide a more refined latex hydrogenation process which treats the
hydrogenated latex with ozone to break the cross-linked polymer
chains which form during or after the latex hydrogenation using the
diimide approach. U.S. Pat. No. 6,552,132 B2 discloses that a
compound can be added before, during or after the latex
hydrogenation to break crosslinks formed during the hydrogenation
using the diimide hydrogenation route. The compound can be chosen
from primary or secondary amines, hydroxylamine, imines, azines,
hydrazones and oximes. U.S. Pat. No. 6,635,718 B2 describes the
process for hydrogenating C.dbd.C bonds of an unsaturated polymer
in the form of an aqueous dispersion by using hydrazine and an
oxidizing compound in the presence of a metal compound containing a
metal atom in an oxidation state of at least 4 (such as Ti(IV),
V(V), Mo(VI) and W(VI)) as the catalyst.
[0009] In Applied Catalysis A: General 276 (2004) 123-128 and
Journal of Applied Polymer Science Vol. 96, (2005) 1122-1125
detailed investigations relating to the hydrogenation of nitrile
butadiene rubber latex via utilization of the diimide hydrogenation
route are presented which cover examining hydrogenation efficiency
and degree of hydrogenation.
[0010] It has been found that there are side reactions at the
interphase of the latex particles and within the polymer phase,
which generate radicals to initiate the crosslinking of polymers in
the latex form. Using radical scavengers did not show any evidence
in helping to suppress the degree of gel formation. Although there
are methods developed to reduce the crosslinking, the
aforementioned diimide route still encounters gel formation
problems, especially when high hydrogenation conversion is
achieved. Therefore, the resulting hydrogenated rubber mass is
difficult to process or is unsuitable for further use because of
its macroscopic three dimensional cross-linked structure.
SUMMARY OF THE INVENTION
[0011] It was an object of the present invention to provide new
diene-based hydrogenated polymers. A further object of the present
invention was to provide processes for producing same hydrogenated
polymers.
[0012] The present invention provides new nanosized diene-based
hydrogenated polymer particles in latex form wherein the particles
have a particle size measured as d.sub.90-value of less than 60 nm,
preferably less than 40 nm, more preferably less than 30 nm and
most preferably less than 20 nm. In one embodiment the diene-based
unsaturated polymer is an acrylonitrile/butadiene polymer.
[0013] Furthermore, the present invention provides a process for
the selective hydrogenation of diene-based unsaturated polymer
particles in latex form, comprising [0014] a) providing diene-based
unsaturated polymer particles having a particle size measured as
d.sub.90-value of less than 60 nm [0015] b) combining the
diene-based unsaturated polymer in latex form with hydrogen or a
hydrogen-source in the presence of [0016] c) a transition metal
containing catalyst and preferably [0017] d) maintaining a
temperature of from about 35.degree. C. to about 180.degree. C.,
preferably from about 80.degree. C. to about 160.degree. C.
[0018] For the purposes of the present invention the
d.sub.90-diameter means that 90% of the particles have a diameter
less than the value indicated.
[0019] For the purpose of the present invention selective
hydrogenation preferably means the hydrogenation of carbon-carbon
double bonds.
DETAILED DESCRIPTION OF THE INVENTION
I) Preparation of the Diene-Based Unsaturated Polymer Particles to
be Hydrogenated According to the Present Invention.
[0020] The diene-based unsaturated polymer particles may be
prepared as a latex by a method comprising [0021] a) polymerization
of at least one diene D and optionally at least one copolymerizable
monomer A [0022] b) in an aqueous medium, preferably water [0023]
c) in the presence of a surfactant, preferably alkylsulfate,
especially a Gemini surfactant, wherein [0024] d) diene D and
optionally at least one copolymerizable monomer A are continuously
preferably in slow and steady feeding rate charged into a reactor
containing the aqueous medium, a polymerization initiator and the
surfactant.
[0025] In one preferred embodiment the diene D and optionally
monomer A are added continuously and slowly. The length of the
addition period depends on reaction conditions, which in principle,
does not allow the monomers D and A to be accumulated into droplets
in the waster phase and usually is at least 10 minutes. In a
further preferred embodiment an amount of less than 1% (in weight,
based on the amount of water), preferably less than 0.1% (in
weight, based on the amount of water) of unreacted diene D and
optionally monomer A in the water phase in the reactor is
maintained.
[0026] In a further preferred embodiment a small amount of a redox
polymerization initiator is used, which is in the range of 0.0.5%
to 5%, preferably 0.1%-1% in weight based on the total amount of
the monomers. The term "diene D and optionally at least one
copolymerisable monomer A are continuously charged into a reactor"
means that not the complete nor almost the complete amount of
reactants are put together into the reactor at the very beginning
of the reaction. The term includes feeding the reactants with
essentially the same feeding rate and concentration including
increasing and decreasing such rates. Furthermore, the term
includes addition of the reactants in small portions during the
reaction.
[0027] The process is useful for the production of nanosize
particles having a d.sub.90-diameter of less than 60 nm.
[0028] The diene-based latex particles are based on at least one
diene monomer, preferably at least one conjugated monomer D. The
diene D can be of any nature. In one embodiment (C.sub.4-C.sub.6)
conjugated dienes are used. Preference is given to 1,3-butadiene,
isoprene, 1-methylbutadiene, 2,3-dimethylbutadiene, piperylene,
chloroprene, or mixtures thereof. Particular preference is given to
1,3-butadiene and isoprene or mixtures thereof. Special preference
is given to 1,3-butadiene.
[0029] Suitable copolymerizable monomers A include acrylonitrile,
methacrylonitrile, styrene, alphamethyl styrene, propyl acrylate,
butyl acrylate, propyl methacrylate, butyl methacrylate, and
unsaturated carboxylic acids selected from fumaric acid, maleic
acid, acrylic acid and methacrylic acid.
[0030] The conjugated diene D forms from about 15 to about 100% by
weight of the carbon-carbon double bond containing polymer in the
latex form. If copolymerizable monomers A are used and selected
from styrene and alphamethyl styrene, the styrene and/or a methyl
styrene monomer preferably forms from about 15 to about 60% by
weight of the polymer. If the other copolymerizable monomers A are
used and selected from acrylonitrile and methacrylonitrile, the
acrylonitrile and/or methacrylonitrile monomer preferably forms
from about 15 to about 50% by weight of the polymer, with the
conjugated diolefin forming from about 50 to about 85% by weight of
the polymer.
[0031] If other copolymerizable monomers A are used and selected
from acrylonitrile and methacrylonitrile and additionally from an
unsaturated carboxylic acid, the acrylonitrile or methacrylonitrile
forms from about 15 to about 50% by weight of the polymer, the
unsaturated carboxylic acid forms from about 1 to about 10% by
weight of the polymer and the conjugated diolefin forms from about
40 to about 85% by weight of the polymer.
[0032] Preferred products include styrene-butadiene polymers of the
random or block types, butadiene-acrylonitrile polymers and
butadiene-acrylonitrile-methacrylic acid polymers. Preferred
butadiene-acrylonitrile polymers have an acrylonitrile content of
from about 25 to about 45% by weight.
[0033] A particularly suitable copolymer to be used is a nitrile
rubber this being a copolymer of an .alpha.,.beta.-unsaturated
nitrile, particularly preferred acrylonitrile, and a conjugated
diene, particularly preferred 1,3-butadiene and optionally one or
more further copolymerizable monomers, such as
.alpha.,.beta.-unsaturated monocarboxylic or dicarboxylic acids,
their esters or amides.
[0034] As .alpha.,.beta.-unsaturated monocarboxylic or dicarboxylic
acids in such nitrile rubbers preference is given to fumaric acid,
maleic acid, acrylic acid and methacrylic acid.
[0035] As esters of .alpha.,.beta.-unsaturated carboxylic acids in
such nitrile rubbers preference is given to using their alkyl
esters and alkoxyalkyl esters. Particularly preferred alkyl esters
of .alpha., .beta.-unsaturated carboxylic acids are methyl
acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate,
tert-butyl acrylate, propyl methacrylate, n-butyl methacrylate,
tert-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl
methacrylate and octyl acrylate. Particularly preferred alkoxyalkyl
esters of .alpha.,.beta.-unsaturated carboxylic acids are
methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate and
methoxyethyl (meth)acrylate. It is also possible to use mixtures of
alkyl esters, e.g. those mentioned above, with alkoxyalkyl esters,
e.g. in the form of those mentioned above.
[0036] A preferred terpolymer is a terpolymer of acrylonitrile,
1,3-butadiene and a third monomer selected from the group
consisting of fumaric acid, maleic acid, acrylic acid, methacrylic
acid, n-butyl acrylate, and tert-butyl acrylate.
[0037] The synthesis of the polymer can be undertaken in latex
form. The polymers are in nanoparticles in the latex.
[0038] The synthesis process can be achieved with use of a chemical
redox initiator, such as ammonium persulphate (APS). Further
polymerisation initiators include thermal initiators such as
potassium persulfate, dialkylperoxides or azocompounds and redox
initiators, for example alkylhydroperoxides such as
diisopropylbenzine, p-menthane and pinane hydroperoxides,
optionally in combination with cholated salts and suitable reducing
agent.
[0039] The initiator can be used in small quantities. An amount of
APS with respect to the total monomers is in the range of 0.0.5% to
5%, preferably 0.1%-1% in weight based on the total amount of the
monomers.
[0040] The synthesis process is preferred carried out with a
surfactant, such as sodium dodecyl sulfate (SDS) and Gemini
16-3-16. The amount of the surfactant can be from about 0.1% to
about 15%, preferably 0.1 to 1% in weight based on the total
monomer amount used.
[0041] In a preferred embodiment water is used as the medium for
the monomers. The amount of water is from about 2 times to about 30
times, preferably from 5 times to 10 times, in weight based on the
amount of the monomers used.
[0042] The synthesis process can be undertaken in a suitable
reactor equipped with temperature regulating and monomer feeding
and agitating means.
[0043] Generally, the reaction temperature suitable for the present
invention is from about 0.degree. C. to about 100.degree. C.,
preferably from about 15.degree. C. to about 70.degree. C.
[0044] According to a preferred embodiment, during the course of
the reaction, the reaction time is from about 0.25 of an hour to
about 100 hours, preferably from about 1 hour to 20 hours,
depending on operational conditions.
[0045] According to a preferred embodiment, during the course of
the reaction, the monomer feeding time is from about 0.25 of an
hour to about 50 hours, preferably from about 1 hour to 10 hours,
depending on operational conditions.
[0046] According to a preferred embodiment, during the course of
the reaction, after the monomer feeding is finished, an aging time
is preferred and it is from about one quarter of an hour to about
50 hours, preferably from about 1 hour to 10 hours, depending on
operational conditions.
[0047] According to a preferred embodiment, when the reaction is
complete, to the extent desired, the reaction vessel can be cooled
(if applicable) and the polymer latex is obtained.
II) Hydrogenation
II.1 Catalysts
[0048] The metal atom of the catalyst is a transition metal,
preferably a noble metal. In one preferred embodiment, the catalyst
is a metal of atomic number 44 to 76 including Ru and Os,
especially Rh.
[0049] In a further preferred embodiment the catalyst is an
organometallic catalyst comprising at least one organic ligand and
a transition metal.
[0050] Preferred organometallic catalysts for the hydrogenation
comprise the following compounds:
Cat 1
[0051] Compounds of the formula L.sub.nMX.sub.2 known from U.S.
Pat. No. 3,454,644 wherein L is a complexing ligand, n is a whole
number from 3 to 4 inclusive, M is a group VIII-A metal of atomic
number from 44 to 76 inclusive, i.e. ruthenium to osmium and X is
halogen. Preferred ligands L are olefins, phenols, thiophenols and
more preferably a carbonyl ligand or a tertiary phosphine
ligand.
[0052] In a further preferred embodiment divalent ruthenium
catalysts of the formula RuXY(CO)ZL.sub.2 or RuX(NO)(CO)L.sub.2
known from U.S. Pat. No. 5,057,581 are preferred wherein X is a
halogen atom or a carboxylate group, Y is a halogen atom, a
hydrogen atom, a phenyl group, a carboxylate group, or a
phenylvinyl group, Z is CO, pyridine, benzonitrile,
trimethylphosphite and L is a phosphine ligand having at least one
bulky alkyl substituent.
Cat 2
[0053] In a further preferred embodiment the organometallic
catalyst is a catalyst combination known from U.S. Pat. No.
5,705,571 including at least one catalyst (A) and at least one
catalyst (B), wherein the catalyst (A) is an unsubstituted or
substituted bis(cyclopentadienyl) Group VIII transition metal
compound, which is represented by the following formula:
(C.sub.5R.sub.nR'.sub.5-n)(C.sub.5R.sub.mR''.sub.5-m)M
wherein
R, R' and R''
[0054] are the same or different and are selected from the group
consisting of hydrogen, C.sub.1-C.sub.8 alkyl and alkoxy groups,
C.sub.6-C.sub.8 aryl and aryloxy groups, C.sub.6-C.sub.8 cycloalkyl
and cycloalkoxy groups, C.sub.1-C.sub.5 hydroxyalkyl groups,
aldehyde groups, carboxyl groups, silyl groups. m and n [0055] are
integers independently from 0 to 5,
C.sub.5R.sub.nR'.sub.5-n and C.sub.5R.sub.mR''.sub.m
[0055] [0056] are the same or different unsubstituted or
substituted cyclopentadienyl groups,
M
[0056] [0057] is a Group VIII transition metal selected from the
groups consisting of cobalt, nickel, rhodium, palladium, platinum
and iridium, wherein the catalyst (B) is an organic lithium
compound having at least one lithium atom or is lithium hydride,
[0058] wherein the organic lithium compound is selected from the
group consisting of R'''Li and R'''Li.sub.2, [0059] wherein R''' is
a C.sub.1-C.sub.30 hydrocarbon moiety or a polymeric moiety, [0060]
wherein the molar ratio of lithium atom to M atom is from 0.1 to
100.
Cat 3
[0061] In a further preferred embodiment the organometallic
catalyst is a catalyst comprising monocyclopentadienyl titanium
compound represented by the following general formula I as main
catalyst:
##STR00001##
wherein R.sub.1, R.sub.2 and R.sub.3 may be the same or different
and are independently selected from the group consisting of halogen
groups, C.sub.1-C.sub.8 alkyl groups, C.sub.1-C.sub.8 alkoxy
groups, C.sub.6-C.sub.20 aryloxy groups, C.sub.6-C.sub.20
cycloalkyl groups, silyl groups, and carbonyl groups; [0062] and an
alkoxylithium compound represented by the following general formula
II as cocatalyst:
[0062] R.sub.4O--Li (II)
wherein R.sub.4 is a substitute group.
Cat 4
[0063] In a particularly preferred embodiment the hydrogenation
process of the present invention can be achieved with use of a
rhodium containing catalyst. Preferably the catalyst is of the
formula:
RhQL.sub.x
wherein Q is hydrogen or an anion, preferably a halide and more
preferably a chloride or bromide ion wherein [0064] L is a ligand
compound of the formula R.sub.mB, wherein [0065] R is a
C.sub.1-C.sub.8-alkyl group, a C.sub.4-C.sub.8-cycloalkyl group a
C.sub.6-C.sub.15-aryl group or a C.sub.7-C.sub.15-aralkyl group,
[0066] B is phosphorus, arsenic, sulfur, or a sulphoxide group, and
[0067] m is 2 or 3, preferably m is 2 when B is sulphur or
sulphoxide, and m is 3 when B is phosphorus or arsenic, and wherein
[0068] x is 2, 3 or 4, preferable x is 3 when Q is halogen and
preferably x is 4 when Q is hydrogen.
[0069] Preferred catalysts include
tris-(triphenylphosphine)-rhodium(I)-chloride,
tris(triphenylphosphine)-rhodium(III)-chloride and
tris-(dimethylsulphoxide)-rhodium(III)-chloride, and
tetrakis-triphenylphosphine)-rhodium hydride, and the corresponding
compounds in which triphenylphosphine moieties are replaced by
tricyclohexylphosphine moieties. The catalyst can be used in small
quantities. An amount in the range of 0.01 to 5.0% preferably 0.02%
to 2.0% by weight based on the weight of the polymer solids content
of the latex.
[0070] The catalyst can be used with a co-catalyst that is a ligand
of formula
R.sub.mB, where
R, m and B are as defined above, and m is preferably 3.
[0071] Preferably B is phosphorus, and the R groups can be the same
or different. Thus, there can be used a triaryl, trialkyl,
tricycloalkyl, diaryl monoalkyl, dialkyl monoaryl diaryl
monocycloalkyl, dialkyl monocycloalkyl, dicycloalkyl monoaryl or
dicycloalkyl monoaryl co-catalysts. Examples of suitable
co-catalyst ligands are given in U.S. Pat. No. 4,631,315, the
disclosure of which is incorporated by reference. The preferred
co-catalyst ligand is triphenylphosphine. The co-catalyst ligand is
preferably used in an amount in the range 0 to 5000%, more
preferably 500 to 3000% by weight, based on the weight of catalyst.
Preferably also the weight ratio of the co-catalyst to the
rhodium-containing catalyst compound is in the range 0 to 50, more
preferably in the range 5 to 30.
11.2 Hydrogenation Process
[0072] The hydrogenation process of the present invention is
preferably carried out with essentially pure hydrogen gas at a
pressure of from about 0.1 to about 20 MPa, preferably at a
pressure of from about 1 to about 16 MPa.
[0073] The hydrogenation process of the present invention can be
undertaken in a suitable reactor equipped with temperature
regulating and agitating means. According to the present invention
polymer latex can be fed into the reactor and degassed as required,
the catalyst can then be added as a pure material or in some cases
as a solution with a small amount of organic solvent and the
reactor can then be pressurized with hydrogen or, in the
alternative, the reactor can be pressurized with hydrogen and the
catalyst added as a pure material or as a solution. Or, according
to the present invention, the catalyst can be added as a pure
material into reactor, and then the polymer latex can be fed into
the reactor and degassed as required.
[0074] Generally, according to the present invention, it is
preferred to heat the reactor device and the polymer latex before
the catalyst is added. The hydrogenation temperature suitable for
the present invention is from about 35.degree. C. to about
180.degree. C., preferably from about 80.degree. C. to about
160.degree. C.
[0075] During the course of the hydrogenation reaction of the
present invention, the hydrogen may be added to the reactor. The
reaction time is from about one quarter of an hour to about 100
hours, depending on operational conditions. The extent to which the
carbon-carbon double bonds in the polymer can be hydrogenated is
from about 80 to about 99.5%, preferably from about 90 to about
99.5%.
[0076] When the hydrogenation reaction is complete to the extent
desired, the reaction vessel can be cooled and vented. The
resultant hydrogenated latex can be used in latex form if required
or be coagulated and washed, to obtain the hydrogenated polymer in
solid form.
[0077] In a preferred embodiment the resulting latex may be blended
with additives known in the art for example an antioxidant and may
be transferred to coagulation and washing vessels with sufficient
agitation to prevent agglomeration. Subsequently, the product may
be fed into a final dewatering device, pelletized, coated with a
partitioning agent and transferred to suitable dryers.
[0078] Nanosized hydrogenated diene-based polymers according to the
present invention can generally be used for the same technical
applications as known latex particles with a higher particle size
as rubber but showing improved properties, especially with respect
to the resistance to degradation by heat, oxygen, and ozone. The
invention is further illustrated but is not intended to be limited
by the following examples in which all parts and percentages are by
weight unless otherwise specified.
EXAMPLES
[0079] The materials which were used in the reaction and analysis
are listed in Table 1.
TABLE-US-00001 TABLE 1 Specification of the Materials Material
Supplier Potassium persulfate Aldrich Chemical Company (KPS, 98%
purity) Sodium dodecyl sulfate Sigma-Aldrich Company (SDS, 95%
purity) NBR latex As described in the examples Acrylonitrile
Aldrich Chemical Company Butadiene LANXESS Inc.
RhCl(PPh.sub.3).sub.3 Synthesized according to literature
procedures (Osborn, J. A.; Jardine, F. H.; Young, J. F.; Wilkinson,
G., J. Chem. Soc. A 1966, 1711-1732) Triphenylphosphine (99%) Strem
Chemicals Hydrogen (99.999%) Praxair
[0080] The following Examples illustrate the scope of the invention
and are not intended to limit the same.
Example 1
NBR Preparation
[0081] 0.2 g of APS, 2 g of Gemini 16-3-16, and 80 ml of water were
put into a 300 mL stainless steel high-pressure reactor (Parr
Instruments) equipped with a impeller stirrer, an addition tube and
a thermal couple. After the temperature was raised to 70.degree.
C., the mixture of 2.5 ml of acrylonitrile and 7.5 ml of butadiene
was added as small portions over a period of 60 min. After addition
of the monomer mixture, an additional 20 min was applied before
cooling to halt the reaction.
Hydrogenation Operation
[0082] A 300 ml glass lined stainless steel autoclave having
temperature control means, an agitator and hydrogen gas addition
points was used. A latex of a butadiene-acrylonitrile polymer
synthesized as above was used. The solid content in the latex was
13% by weight. The mean diameter of the polymer particles in the
latex was about 26 nm. 100 ml of such a latex, 0.13 gram of the
catalyst RhCl(PPh.sub.3).sub.3 and 1.3 gram of PPh.sub.3 were
charged into the reactor. The agitation speed was 600 rpm. The
latex was then degassed with hydrogen. The temperature was
increased to 160.degree. C. and hydrogen pressure was raised up to
1000 psi (6.8 MPa). The reaction time was 0.25 hr. The
hydrogenation degree was 43.2%.
[0083] The result indicates that when such synthesized latex of
nanosized diene-based polymer particles, the hydrogenation speed
can be significantly speeded up.
Example 2
[0084] The same procedures and reaction conditions as described in
Example 1 were employed except the hydrogenation reaction time was
0.38 hr. 81.9% of hydrogenation degree was obtained.
Example 3
[0085] The same procedures and reaction conditions as described in
Example 1 were employed except the hydrogenation reaction time was
1 hr. A hydrogenation degree of 91% was achieved.
[0086] The result indicated that within 1 hour the hydrogenation
degree reached over 90%.
[0087] Although the invention has been described in detail in the
foregoing for the purpose of illustration, it is to be understood
that such detail is solely for that purpose and that variations can
be made therein by those skilled in the art without departing from
the spirit and scope of the invention except as it may be limited
by the claims.
* * * * *