U.S. patent application number 11/374268 was filed with the patent office on 2006-12-07 for microgels combined with functional additives.
Invention is credited to Achim Fessenbecker, Thomas Fruh, Patrick Galda, Werner Obrecht, Gunther Steppan, Torsten Ziser.
Application Number | 20060275691 11/374268 |
Document ID | / |
Family ID | 36609243 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060275691 |
Kind Code |
A1 |
Fessenbecker; Achim ; et
al. |
December 7, 2006 |
Microgels combined with functional additives
Abstract
The invention relates to a composition comprising at least one
microgel and at least one functional additive, to processes for the
preparation thereof, to uses of the compositions, and to
microgel-containing polymers, rubbers, lubricants, coatings, etc.
prepared therefrom.
Inventors: |
Fessenbecker; Achim;
(Waghausel, DE) ; Galda; Patrick; (Karlsruhe,
DE) ; Ziser; Torsten; (Birkenau, DE) ; Fruh;
Thomas; (Limburgerhof, DE) ; Steppan; Gunther;
(Oftersheim, DE) ; Obrecht; Werner; (Moers,
DE) |
Correspondence
Address: |
LANXESS CORPORATION
111 RIDC PARK WEST DRIVE
PITTSBURGH
PA
15275-1112
US
|
Family ID: |
36609243 |
Appl. No.: |
11/374268 |
Filed: |
March 13, 2006 |
Current U.S.
Class: |
430/137.15 |
Current CPC
Class: |
C08K 5/0008 20130101;
C08J 2321/00 20130101; C08K 5/0008 20130101; C08L 21/00 20130101;
C08J 3/075 20130101 |
Class at
Publication: |
430/137.15 |
International
Class: |
G03G 5/00 20060101
G03G005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 24, 2005 |
DE |
10 2005 014271.0 |
Claims
1. Composition, containing at least one microgel (B) and at least
one functional additive (C).
2. Composition according to claim 1, comprising at least one
non-crosslinkable organic medium (A).
3. Composition according to either claim 1 or claim 2,
characterised in that the primary particles of the microgel (B)
have approximately spherical geometry.
4. Composition according to any one of claims 1 to 3, characterised
in that the deviation in the diameter of an individual primary
particle of the microgel (B), defined as [(d1-d2)/d2].times.100,
wherein d1 and d2 are two arbitrary diameters of the primary
particle and d1>d2, is less than 250%.
5. Composition according to claim 4, wherein the above-mentioned
deviation is less than 50%.
6. Composition according to any one of claims 1 to 5, characterised
in that the primary particles of the microgel (B) have an average
particle size from 5 to 500 nm.
7. Composition according to any one of claims 1 to 6, characterised
in that the primary particles of the microgel (B) have an average
particle size of less than 99 nm.
8. Composition according to any one of claims 1 to 7, characterised
in that the microgels (B) comprise fractions which are insoluble in
toluene at 23.degree. C. of at least approximately 70% by
weight.
9. Composition according to any one of claims 1 to 8, characterised
in that the microgels (B) have a swelling index of less than 80 in
toluene at 23.degree. C.
10. Composition according to any one of claims 1 to 9,
characterised in that the microgels (B) have glass transition
temperatures from -100.degree. C. to +120.degree. C.
11. Composition according to any one of claims 1 to 10,
characterised in that the microgel (B) is a crosslinked microgel
not crosslinked by high-energy radiation.
12. Composition according to any one of claims 1 to 11,
characterised in that the microgels (B) have a glass transition
range greater than approximately 5.degree. C.
13. Composition according to any one of claims 1 to 12,
characterised in that the microgels (B) are obtainable by emulsion
polymerisation.
14. Composition according to any one of claims 1 to 13,
characterised in that the microgel (B) is based on rubber.
15. Composition according to any one of claims 1 to 14,
characterised in that the microgel (B) is based on homopolymers or
random copolymers.
16. Composition according to any one of claims 1 to 15,
characterised in that the microgel (B) is modified by functional
groups reactive toward C.dbd.C double bonds.
17. Composition according to any one of claims 1 to 16, wherein the
functional additive (C) is at least one compound containing at
least one heteroatom selected from the group consisting of sulphur,
phosphorus, halogen, oxygen and metals.
18. Composition according to any one of claims 1 to 17, wherein the
functional additive (C) is at least one compound containing at
least two heteroatoms selected from the group consisting of
sulphur, phosphorus, halogen, oxygen and metals.
19. Composition according to any one of claims 1 to 16, wherein the
functional additive (C) is at least one compound selected from the
group consisting of: compounds suitable as high-pressure additives
such as organic polysulphides based on sulphurized olefins, organic
polysulphides based on sulphurized triglycerides, fatty acid
esters, fatty alcohols, etc., organic polysulphides based on
sulphurized oils; other sulphur-containing compounds such as
xanthogenates, thiourea derivatives, etc.; organic chlorine
compounds such as, for example, chlorinated paraffins, etc.;
organic nitrogen compounds such as, for example, carbamic acid
esters, etc.; compounds suitable as antiwear additives such as
phosphorus-containing components, for example phosphoric acid
esters, phosphonates, alkyl aryl phosphines, phosphites, etc.;
phosphorus- and sulphur-containing derivatives such as, for
example, metal dialkyl dithiophosphates, diaryl and dialkyl
dithiophosphates, monoalkyl and monoaryl dithiophosphates, etc.;
phosphorus- and nitrogen-containing compounds such as, for example,
amine-neutralised phosphoric acid derivatives, etc.; phosphorus-
and chlorine-containing compounds such as, for example,
chlorine-containing phosphorus compounds; compounds suitable as
antiwear additives such as neutralised alkali and alkaline-earth
salts of sulphonic acids and the derivatives thereof such as, for
example, esters, etc., neutralised monocarboxylic and dicarboxylic
acids such as, for example, naphthenic acid, salicylic acid, etc.,
and the derivatives thereof such as, for example, alkali and
alkaline-earth salts, esters, amides, etc.; fatty oil and fatty
acid derivatives; compounds suitable as non-ferrous metal
inhibitors such as triazole derivatives, for example benzotriazole,
thiadiazole derivatives such as, for example,
dimercaptothiadiazoles, etc.; compounds suitable as antioxidants
such as alkyl/aryl-substituted phenol derivatives,
alkyVaryl-substituted amine derivatives; other phosphorus or
sulphur-containing phenol/amine derivatives; compounds suitable as
friction modifiers such as metal-containing organic compounds such
as, for example, molybdenum, antimony, dithiocarbamates or
dithiophosphates, etc.; fatty acid or fatty alcohol derivatives
such as, for example, fatty acid amides, polyolesters, phthalates,
sebacates, benzoates, adipates, etc.; compounds suitable as
surface-active substances such as detergents, for example
alkyl/aryl fatty acid derivatives, alkyVaryl sulphonic acid
derivatives, alkyl phenol derivatives, etc.; compounds suitable as
dispersing agents such as, for example, esterification products of
dicarboxylic acids and glycols, etc.; also pour-point depressants,
viscosity index improvers, defoaming agents, deaerators, flow
control agents, tackifiers, etc.; compounds suitable as catalysts
such as, for example, accelerators such as, for example,
mercaptobenzothiadiazole derivatives, etc., compounds suitable as
crosslinking agents such as, for example, urea, triazine, carbamic
acid derivatives, etc.
20. Composition according to any one of claims 1 to 19, wherein at
a temperature of 120.degree. C. the functional additive has a
viscosity of less than 1,000 mPas.
21. Composition according to any one of claims 1 to 20, containing
no component (A).
22. Composition according to any one of claims 1 to 21, consisting
of the components (B) and (C).
23. Composition according to any one of claims 1 to 22, containing
from 0.1 to 99.9, preferably from 10 to 90, % by weight of the
microgel (B), based on the total quantity of the composition.
24. Composition according to any one of claims 1 to 23,
characterised in that it contains from 0.1 to 99.9, preferably from
10 to 90, % by weight of the functional additive (C).
25. Composition according to any one of claims 1 to 24,
characterised in that it additionally contains fillers.
26. Composition according to any one of claims 1 to 21,
characterised in that it was prepared by mixing the functional
additive (C), the microgel (B) and optionally also the
non-crosslinkable organic medium (A) using a homogeniser, a bead
mill (attrition mill), a triple roller, a single or multiple
extruder screw, a kneader, an Ultra-Turrax device and/or a
dissolver.
27. Composition according to claim 26, characterised in that it was
prepared using a homogeniser, a bead mill (attrition mill), a
triple roller or a dissolver.
28. Composition according to any one of claims 1 to 27,
characterised in that it has a viscosity from 2 mPas up to
50,000,000 mPas at a speed of rotation of 5 s.sup.-1, determined
using a cone-and-plate measuring system to DIN 53018 at 20.degree.
C.
29. Composition according to any one of claims 1 to 28,
characterised in that the microgel (B) has a swelling index from 1
to 15 in toluene at 23.degree. C.
30. Composition according to any one of claims 1 to 29,
characterised in that the microgels (B) comprise fractions which
are insoluble in toluene at 23.degree. C. of at least 95% by
weight.
31. Composition according to any one of claims 1 to 30,
characterised in that the microgel is not modified by hydroxyl
groups.
32. Composition according to any one of claims 1 to 31,
characterised in that the microgel is not modified.
33. Use of the composition according to any one of claims 1 to 32
for incorporation into thermoplastic polymers, rubbers or
thermoplastic elastomers.
34. Use of the composition according to any one of claims 1 to 22
for the preparation of microgel-containing polymers.
35. Use according to claim 34 for the preparation of
microgel-containing rubbers.
36. Use according to claim 34 for the preparation of
microgel-containing thermoplastic elastomers.
37. Use of the compositions according to any one of claims 1 to 32
for the preparation of lubricants, mouldings or coatings.
38. Use of the composition according to claim 37 for the
preparation of lubricating grease or modified lubricating oils.
39. Use of the compositions according to any one of claims 1 to 32
as an additive for plastics materials, rubbers, coating agents or
lubricants.
40. Plastics materials, rubbers, thermoplastic elastomers, coating
agents or lubricants containing the compositions according to any
one of claims 1 to 32.
Description
[0001] The invention relates to a composition comprising at least
one microgel and at least one functional additive, to processes for
the preparation thereof, to uses of the compositions, and to
microgel-containing polymers, rubbers, lubricants, coatings, etc.
prepared therefrom.
[0002] It is known to use rubber gels, including modified rubber
gels, in mixtures with a wide range of rubbers, for example to
improve rolling resistance in the manufacture of motor vehicle
tyres (see, for example, DE 42 20 563, GB-PS 10 78 400 EP 405 216
and EP 854 171).
[0003] Dispersions of silicone-containing graft polymers in liquid
amides, which are also prepared from aqueous lattices, are known
from DE-A-3742180. However, in the case of the dispersions
described in said document, the water is only substantially
separated off, and complete separation is difficult.
[0004] Compositions containing microgels and organic media have
basically been described in non-anticipatory international
application PCT/EP2004/052290 of the present applicant.
[0005] The inventors of the present invention have found that it is
possible finely to disperse microgels, in particular in liquid
functional additives, for example using a homogeniser. The division
of the microgels into the primary particle range is, for example, a
prerequisite for rendering the nano-characteristics of the
microgels particularly useful. The compositions according to the
invention containing the specific microgels can open up a large
number of microgel applications that were not previously accessible
using the microgels themselves.
[0006] The microgel/additive combinations have highly beneficial
characteristics, for example rheology, consistency, shear
stability, thickening effect, etc. The inventors were thus able to
prepare combinations of conventional commercial liquid lubricant
additives and microgels that, in combination, incorporate positive
characteristics of both systems. It has thus been found that a
liquid additive is bound by the microgel at the surface or in the
network and can be introduced in bound form into a lubricant, for
example, from where it is also released again under specific
conditions. Surprisingly, it has been found not only that additives
allow paste- or fat-like combinations to be obtained, but also that
these combinations in fact develop synergistic effects. A
transparent "additive fat" having consistency values (dripping
temperature, penetration) typical of fats, in contrast to opaque
fat structures, is thus obtained, for example, from the combination
of a sulphur-functionalised olefin and a microgel. If this additive
fat is introduced into base fluids in conventional concentrations,
a lubricant formulation that behaves synergistically with respect
to the measured values determined for the individual components,
additive or microgel, is obtained. Further combinations of
sulphur-containing additives or phosphorus-containing additives
display a similar, usually paste-like consistency, in some cases a
fat-like consistency.
[0007] The present invention therefore provides a composition
containing at least one microgel (B) and at least one functional
additive (C).
Microgels (B)
[0008] The microgel (B) used in the composition according to the
invention is a crosslinked microgel. In a preferred embodiment, the
microgel is not crosslinked by high-energy radiation. The term
"high-energy" radiation expediently refers, in this context, to
electromagnetic radiation having a wavelength of less than 0.1
.mu.m. The use of microgels crosslinked by high-energy radiation,
as described for example in Chinese Journal of Polymer Science,
Vol. 20, No. 2, (2002), 93-98, is disadvantageous, as it is
virtually impossible to prepare on an industrial scale microgels
crosslinked by high-energy radiation. The use of high-energy
radiation from radioactive sources such as radioactive cobalt is
also associated with serious safety problems.
[0009] In a preferred embodiment of the invention, the primary
particles of the microgel (B) have an approximately spherical
geometry. According to DIN 53206:1992-08, the microgel particles,
which may be recognised as individual entities using suitable
physical methods (electron microscope) and are dispersed in the
coherent phase, are designated as primary particles (cf., for
example, R6 mpp Lexikon, Lacke und Druckfarben, Georg Thieme
Verlag, 1998). The term an "approximately spherical" geometry means
that, on viewing the composition, for example using an electron
microscope, the dispersed primary particles of the microgels may be
seen to have a substantially circular surface. Since the microgels
do not substantially change their form or morphology during
processing of the compositions according to the invention, the
foregoing and following remarks similarly also apply to the
microgel-containing compositions obtained using the composition
according to the invention such as, for example, plastics
materials, coating agents, lubricants or the like.
[0010] In the primary particles of the microgel (B) that are
contained in the composition according to the invention, the
deviation in the diameter of an individual particle, defined as
[(d1-d2)/d2].times.100, wherein d1 and d2 are two arbitrary
diameters of the primary particle and d1>d2, is preferably less
than 250%, more preferably less than 100%, even more preferably
less than 80%, even more preferably less than 50%.
[0011] Preferably at least 80%, more preferably at least 90%, even
more preferably at least 95% of the primary particles of the
microgel exhibit a diameter deviation, defined as
[(d1-d2)/d2].times.100, wherein d1 and d2 are two arbitrary
diameters of the primary particle and d1>d2, of less than 250%,
preferably less than 100%, more preferably less than 80%, even more
preferably less than 50%.
[0012] The above-mentioned deviation in the diameters of the
individual particles can be determined by the following method.
First of all, a thin section of the compacted composition according
to the invention is prepared. A transmission electron micrograph
enlarged by a factor of, for example, 10,000 or 200,000 is then
prepared. In an area of 833.7.times.828.8 nm, the largest and the
smallest diameter of 10 microgel primary particles are determined
as d1 and d2. If the above-defined deviation is in each case less
than 250%, preferably less than 100%, even more preferably less
than 80%, even more preferably less than 50%, in at least 80%,
preferably at least 90%, more preferably at least 95% of the
measured microgel primary particles, the microgel primary particles
exhibit the above-defined feature of deviation.
[0013] If the concentration of the microgels in the composition is
sufficiently high that the visible microgel primary particles are
markedly superimposed, evaluation may be facilitated by appropriate
prior dilution of the test sample.
[0014] In the composition according to the invention, the primary
particles of the microgel (B) preferably exhibit an average
particle diameter from 5 to 500 nm, more preferably from 20 to 400
nm, more preferably from 20 to 300 nm, more preferably from 20 to
250 nm, even more preferably from 20 to 99, even more preferably
from 40 to 80 (diameters to DIN 53206). The preparation of
particularly finely divided microgels by emulsion polymerisation
takes place by controlling the reaction parameters in a manner
known per se (see, for example, H. G. Elias, Makromolekule, Vol. 2,
Technologie, fifth edition, page 99 ff.).
[0015] Since the morphology of the microgels basically does not
change during further processing of the composition according to
the invention, the average particle diameter of the dispersed
primary particles substantially corresponds to the average particle
diameter of the dispersed primary particles, in the products of
further processing obtained using the composition according to the
invention such as microgel-containing plastics materials,
lubricants, coatings, etc. This is a particular advantage of the
composition according to the invention. Customers may in some cases
be provided with tailor-made, liquid microgel formulations, which
are stable in storage, have a defined microgel morphology and may
easily be processed by customers in the desired applications.
Complex prior dispersion, homogenisation or even preparation of
microgels is no longer required, so it is expected that microgels
of this type will also be used in fields in which their use
previously seemed excessively complex.
[0016] In the composition according to the invention, the microgels
(B) expediently comprise fractions which are insoluble in toluene
at 23.degree. C. (gel content) of at least approximately 70% by
weight, more preferably at least approximately 80% by weight, even
more preferably at least 90% by weight.
[0017] The fraction that is insoluble in toluene is determined in
toluene at 23.degree. C. 250 mg of the microgel are steeped in 20
ml toluene for 24 hours at 23.degree. C. while shaking. After
centrifugation at 20,000 rpm, the insoluble fraction is separated
and dried. The gel content is determined from the quotient of the
dried residue and the weighed portion and is given as a percentage
by weight.
[0018] In the composition according to the invention, the microgels
(B) expediently exhibit a swelling index of less than approximately
80, more preferably of less than 60, even more preferably of less
than 40 in toluene at 23.degree. C. The swelling indices of the
microgels (Qi) may thus particularly preferably be between 1-15 and
1-10. The swelling index is calculated from the weight of the
solvent-containing microgel steeped in toluene for 24 hours at
23.degree. C. (after centrifugation at 20,000 rpm) and the weight
of the dry microgel: Qi=Wet weight of the microgel/dry weight of
the microgel.
[0019] In order to determine the swelling index, 250 mg of the
microgel is steeped in 25 ml toluene for 24 hours while shaking.
The gel is centrifuged off, weighed and then dried at 70.degree. C.
until a constant weight is reached and dried again.
[0020] In the composition according to the invention, the microgels
(B) expediently exhibit glass transition temperatures Tg from
-100.degree. C. to +120.degree. C., more preferably from
-100.degree. C. to +100.degree. C., even more preferably from
-80.degree. C. to +80.degree. C. In rare cases, microgels which,
owing to their high degree of crosslinking, do not exhibit a glass
transition temperature may also be used.
[0021] Moreover, the microgels (B) used in the composition
according to the invention preferably exhibit a glass transition
temperature range greater than 5.degree. C., preferably greater
than 10.degree. C., more preferably greater than 20.degree. C.
Microgels that exhibit such a glass transition temperature range,
in contrast to completely homogeneously radiation-crosslinked
microgels, are generally not completely homogenised. As a result,
the change in modulus from the matrix phase to the dispersed phase
is not direct in the microgel-containing plastics material
compositions prepared, for example, from the compositions according
to the invention. Accordingly, in the event of these compositions
being subjected to abrupt stress, there are no tearing effects
between the matrix and the dispersed phase, so the mechanical
characteristics, the swelling behaviour and the stress corrosion
cracking, etc. are advantageously influenced.
[0022] The glass transition temperatures (Tg) and the glass
transition temperature range (.DELTA.Tg) of the microgels are
determined by differential scanning calorimetry (DSC). under the
following conditions: Two cooling/heating cycles are carried out
for determining Tg and .DELTA.Tg. Tg and .DELTA.Tg are determined
in the second heating cycle. In order to determine these values,
10-12 mg of the selected microgel are placed in a Perkin-Elmer DSC
sample container (standard aluminium pan). The first DSC cycle is
carried out by first cooling the sample with liquid nitrogen to
-100.degree. C. and then heating it at a rate of 20 K/min to
+150.degree. C. The second DSC cycle is started by immediate
cooling of the sample as soon as a sample temperature of
+150.degree. C. has been reached. The cooling takes place at a rate
of approximately 320 K/min. In the second heating cycle, as in the
first cycle, the sample is heated once again to +150.degree. C. The
heating rate in the second cycle is again 20 K/min. Tg and
.DELTA.Tg are determined graphically on the DSC curve of the second
heating process. For this purpose, three straight lines are plotted
on the DSC curve. The first straight line is plotted on the curved
portion of the DSC curve below Tg, the second straight line on the
branch of the curve extending through Tg with a turning point and
the third straight line on the branch of the DSC curve above Tg.
Three straight lines with two intersections are thus obtained. Each
intersection is characterised by a characteristic temperature. The
glass transition temperature Tg is obtained as an average value of
these two temperatures and the glass transition temperature range
.DELTA.Tg is obtained from the difference between the two
temperatures.
[0023] The microgels that are contained in the composition
according to the invention and are preferably not crosslinked by
high-energy radiation may be prepared in a manner known per se
(see, for example, EP-A-405 216, EP-A-854 171, DE-A 4220563, GB-PS
1078400, DE 197 01 489.5, DE 197 01 488.7, DE 198 34 804.5, DE 198
34 803.7, DE 198 34 802.9, DE 199 29 347.3, DE 199 39 865.8, DE 199
42 620.1, DE 199 42 614.7, DE 100 21 070.8, DE 100 38 488.9, DE 100
39 749.2, DE 100 52 287.4, DE 100 56 311.2 and DE 100 61 174.5).
Patents (applications) EP-A-405 216, DE-A 4220563 and GB-PS 1078400
claim the use of CR, BR and NBR microgels in mixtures with double
bond-containing rubbers. DE 197 01 489.5 discloses the use of
subsequently modified microgels in mixtures with double
bond-containing rubbers such as NR, SBR and BR.
[0024] The term "microgels" expediently refers to rubber particles
obtained, in particular, by crosslinking the following rubbers:
[0025] BR: polybutadiene, [0026] ABR: butadiene/acrylic acid/C1-4
alkylester copolymers, [0027] IR: polyisoprene, [0028] SBR:
styrene/butadiene copolymers having styrene contents from 1-60,
preferably 5-50 percent by weight, [0029] X-SBR: carboxylated
styrene/butadiene copolymers [0030] FKM: fluorine rubber, [0031]
ACM: acrylate rubber, [0032] NBR: polybutadiene/acrylonitrile
copolymers having acrylonitrile contents from 5-60, preferably
10-50 percent by weight, [0033] X-NBR: carboxylated nitrile rubbers
[0034] CR: polychloroprene [0035] IIR: isobutylene/isoprene
copolymers having isoprene contents from 0.5-10 percent by weight,
[0036] BIIR: brominated isobutylene/isoprene copolymers having
bromine contents from 0.1-10 percent by weight, [0037] CIIR:
chlorinated isobutylene/isoprene copolymers having bromine contents
from 0.1-10 percent by weight, [0038] HNBR: partially and
completely hydrogenated nitrile rubbers [0039] EPDM:
ethylene/propylene/diene copolymers, [0040] EAM: ethylene/acrylate
copolymers, [0041] EVM: ethylene/vinyl acetate copolymers [0042] CO
and ECO: epichlorohydrin rubbers, [0043] Q: silicone rubbers,
except silicone graft polymers, [0044] AU: polyester urethane
polymers, [0045] EU: polyether urethane polymers [0046] ENR:
epoxidized natural rubber or mixtures thereof.
[0047] The uncrosslinked microgel starting products are expediently
prepared by the following methods: [0048] 1. Emulsion
polymerisation [0049] 2. Solution polymerisation of rubbers not
accessible via variant 1 [0050] 3. Naturally occurring latices such
as, for example, natural rubber latex may of course also be
used.
[0051] In the thermosetting plastics composition according to the
invention, the microgels (B) used are preferably ones that may be
obtained by emulsion polymerisation and crosslinking.
[0052] In the preparation of the microgels used according to the
invention by emulsion polymerisation, the following radically
polymerizable monomers, for example, are used: butadiene, styrene,
acrylonitrile, isoprene, acrylic and methacrylic acid ester.
Tetrafluoroethylene, vinylidene fluoride, hexafluoropropene,
2-chlorobutadiene, 2,3-dichlorobutadiene and double bond-containing
carboxylic acids such as, for example, acrylic acid, methacrylic
acid, maleic acid, itaconic acid, etc., double bond-containing
hydroxy compounds such as, for example, hydroxyethyl methacrylate,
hydroxyethyl acrylate, hydroxybutyl methacrylate,
amine-functionalised (meth)acrylate, acrolein,
N-vinyl-2-pyrrolidone, N-allyl-urea und N-allyl-thiourea, secondary
amino-(meth)-acrylic ester and 2-tert-butylaminoethyl methacrylate
and 2-tert-butylaminoethyl methacrylamide, etc. The rubber gel may
be crosslinked directly during emulsion polymerisation, for example
by copolymerisation with crosslinking multifunctional compounds, or
by subsequent crosslinking as described below. Direct crosslinking
constitutes a preferred embodiment of the invention. Preferred
multifunctional comonomers are compounds comprising at least two,
preferably two to four copolymerizable C.dbd.C double bonds, such
as diisopropenylbenzene, divinylbenzene, divinylether,
divinylsulphone, diallyl phthalate, triallyl cyanurate, triallyl
isocyanurate, 1,2-polybutadiene, N,N'-m-phenylene maleimide,
2,4-toluylenebis(maleimide) and/or triallyl trimellitate. Other
suitable compounds include the acrylates and methacrylates of
polyhydric, preferably dihydric to tetrahydric C2 to C10 alcohols
such as ethylene glycol, propanediol-1,2, butanediol, hexanediol,
polyethylene glycol comprising 2 to 20, preferably 2 to 8
oxyethylene units, neopentyl glycol, bisphenol-A, glycerol,
trimethylolpropane, pentaerythritol, sorbitol comprising
unsaturated polyesters of aliphatic diols and polyols, and also
maleic acid, fumaric acid and/or itaconic acid.
[0053] The crosslinking to rubber microgels during emulsion
polymerisation may also take place by continuing polymerisation
until high conversions are achieved or, in the monomer feed
process, by polymerisation with high internal conversions. It is
also possible to carry out emulsion polymerisation in the absence
of regulators.
[0054] For crosslinking the uncrosslinked or lightly crosslinked
microgel starting products after emulsion polymerisation, it is
best to use the latices that are obtained during emulsion
polymerisation. In principle, this method may also be applied to
non-aqueous polymer dispersions accessible in a different manner,
for example by redissolving. Natural rubber latices may also be
crosslinked in this way.
[0055] Examples of suitable crosslinking chemicals include organic
peroxides such as dicumyl peroxide, t-butylcumyl peroxide,
bis-(t-butyl-peroxy-isopropyl)benzene, di-t-butyl peroxide,
2,5-dimethylhexane-2,5-dihydroperoxide,
2,5-dimethylhexine-3,2,5-dihydroperoxide, dibenzoyl peroxide,
bis-(2,4-dichlorobenzoyl)peroxide, t-butyl perbenzoate and also
organic azo compounds such as azo-bis-isobutyronitrile und
azo-bis-cyclohexanenitrile and dimercapto und polymercapto
compounds such as dimercaptoethane, 1,6-dimercaptohexane,
1,3,5-trimercaptotriazine und mercapto-terminated polysulphide
rubbers such as mercapto-terminated reaction products of
bis-chloroethyl formal with sodium polysulphide.
[0056] The optimum temperature for carrying out the post-curing is
of course dependent on the reactivity of the crosslinking agent. It
may be carried out at temperatures from ambient temperature to
approximately 180.degree. C., optionally under elevated pressure
(see in this regard Houben-Weyl, Methoden der organischen Chemie,
fourth edition, Vol. 14/2, page 848). Peroxides are particularly
preferred crosslinking agents.
[0057] C.dbd.C double bond-containing rubbers may also be
crosslinked to microgels in dispersion or emulsion with
simultaneous partial or complete hydrogenation of the C.dbd.C
double bond by hydrazine, as disclosed in U.S. Pat. No. 5,302,696
or U.S. Pat. No. 5,442,009 or optionally other hydrogenation
agents, for example organometallic hydride complexes.
[0058] Before, during or after the post-curing, the particles may
optionally be enlarged by agglomeration.
[0059] In the preparation process preferably used according to the
invention without the application of high-energy radiation,
microgels that are incompletely homogeneously crosslinked and may
exhibit the above-described advantages are always obtained.
[0060] Rubbers prepared by solution polymerisation may also be used
as starting products for the preparation of the microgels. In such
cases, suitable organic solutions of these rubbers are used as
starting materials.
[0061] The desired sizes of the microgels are prepared by mixing
the rubber solution in a liquid medium, preferably in water,
suitable surface-active auxiliaries such as, for example,
surfactants optionally being added using suitable units, so a
dispersion of the rubber in the appropriate particle size range is
obtained. For crosslinking the dispersed solution rubbers, the
procedure is the same as that previously described for the
subsequent crosslinking of emulsion polymers. Suitable crosslinking
agents include the above-mentioned compounds, wherein the solvent
used for preparing the dispersion may optionally be removed, for
example by distillation, prior to crosslinking.
[0062] Both non-modified microgels comprising substantially no
reactive groups, in particular at the surface, and modified
microgels comprising functional groups, in particular at the
surface, may be used as microgels for preparing the composition
according to the invention. Said modified microgels may be prepared
by chemical reaction of the microgels that have already been
crosslinked with chemicals that are reactive toward C.dbd.C double
bonds. These reactive chemicals are, in particular, compounds by
means of which polar groups such as, for example, aldehyde,
hydroxyl, carboxyl, nitrile, etc., groups and sulphur-containing
groups such as, for example, mercapto, dithiocarbamate,
polysulphide, xanthogenate, thiobenzothiazole and/or
dithiophosphoric acid groups and/or unsaturated dicarboxylic acid
groups may be chemically bound to the microgels. This also applies
to N,N'-m-phenylenediamine. The aim of the microgel modification is
to improve the microgel compatibility if the composition according
to the invention is used for preparing the subsequent matrix, into
which the microgel is incorporated, or the composition according to
the invention is used for incorporation into a matrix to achieve
effective dispersibility during the preparation process and
effective linking.
[0063] Particularly preferred modification methods include the
grafting of the microgels with functional monomers and the reaction
with low-molecular agents.
[0064] The starting material for the grafting of the microgels with
functional monomers is expediently the aqueous microgel dispersion,
which is reacted under the conditions of radical emulsion
polymerisation with polar monomers such as acrylic acid,
methacrylic acid, itaconic acid, hydroxyethyl-(meth)-acrylate,
hydroxypropyl-(meth)-acrylate, hydroxybutyl-(meth)-acrylate,
acrylamide, methacrylamide, acrylonitrile, acrolein,
N-vinyl-2-pyrrolidone, N-allyl-urea and N-allyl-thiourea and also
secondary amino-(meth)-acrylic esters such as
2-tert-butylaminoethyl methacrylate und 2-tert-butylaminoethyl
methacrylamide. Microgels having a core/shell morphology are thus
obtained, wherein the shell is to exhibit a high degree of
compatibility with the matrix. It is desirable that the monomer
used in the modification step grafts as quantitatively as possible
onto the unmodified microgel. Expediently, the functional monomers
are added prior to the complete crosslinking of the microgels.
[0065] In principle, grafting of the microgels in non-aqueous
systems is also conceivable, thus also allowing monomer
modification using ionic polymerisation methods.
[0066] The following reagents are particularly suitable for a
surface modification of the microgels with low-molecular agents:
elemental sulphur, hydrogen sulphide and/or alkylpolymercaptans
such as 1,2-dimercaptoethane or 1,6-dimercaptohexane, and also
dialkyl and dialkylaryl dithiocarbamate and the alkali-metal salts
of dimethyl dithiocarbamate and/or dibenzyl dithiocarbamate, also
alkyl and aryl xanthogenates such as potassium ethyl xanthogenate
und sodium isopropyl xanthogenate and the reaction with the alkali
or alkaline-earth salts of dibutyldithiophosphoric acid and
dioctyidithiophosphoric acid and dodecyldithiophosphoric acid. The
aforementioned reactions may also advantageously be carried out in
the presence of sulphur, wherein the sulphur is also incorporated,
with the formation of polysulphide bonds. For the addition of this
compound, radical initiators such as organic and inorganic
peroxides and/or azo initiators may be added.
[0067] Modification of double bond-containing microgels, for
example by ozonolysis and by halogenation with chlorine, bromine
and iodine, is also possible. A further reaction of modified
microgels, for example the preparation of hydroxyl group-modified
microgels from epoxidised microgels, is also understood as a
chemical modification of microgels.
[0068] In a preferred embodiment, the microgels are modified by
hydroxyl groups, in particular at the surface thereof. The hydroxyl
group content of the microgels is determined by reaction with
acetic anhydride and titration of the acetic acid hereby released
with KOH to DIN 53240 as a hydroxyl value having the units mg KOH/g
polymer. The hydroxyl value of the microgels is preferably between
0.1 and 100, more preferably between 0.5 and 50 mg KOH/g
polymer.
[0069] The amount of modification agent used is determined by the
efficacy thereof and individual requirements, and is in the range
from 0.05 to 30 percent by weight, based on the total amount of
rubber microgel used, 0.5 to 10 percent by weight being
particularly preferred.
[0070] The modification reactions may be carried out at
temperatures from 0-180.degree. C., preferably 20-95.degree. C.,
optionally under a pressure of 1-30 bar. The modifications may be
carried out on rubber microgels in substance or in the form of the
dispersion thereof, wherein inert organic solvents or even water
may be used as a reaction medium in the latter case. Particularly
preferably, the modification is carried out in an aqueous
dispersion of the crosslinked rubber.
[0071] The average diameter of the prepared microgels may be
adjusted with high accuracy, for example, to 0.1 micrometres (100
nm)+/-0.01 micrometre (10 nm), so a particle size distribution, for
example, wherein at least 75% of all of the microgel particles are
between 0.095 micrometres and 0.105 micrometres, is achieved. Other
average diameters of the microgels, in particular in the range
between 5 and 500 nm, may be prepared and used with equal accuracy
(at least 75% by weight of all of the particles lie in a range of
+10% above and below the peak of the integrated particle size
distribution curve (determined by light scattering)). This allows
the morphology of the microgels dispersed in the composition
according to the invention to be adjusted with almost "pinpoint"
accuracy, and hence the properties of the composition according to
the invention and the plastics materials prepared therefrom, for
example, to be adjusted.
[0072] The microgels prepared in this manner, which are preferably
based on BR, SBR, NBR, SNBR, or acrylonitrile or ABR, may be worked
up, for example, by evaporation, coagulation, by co-coagulation
with a further latex polymer, by freeze coagulation (cf. U.S. Pat.
No. 2,187,146) or by spray-drying. In the case of working up by
spray-drying, conventional commercial flow promotion agents such as
CaCO.sub.3 or silicic acid may be added.
[0073] In a preferred embodiment of the composition according to
the invention, the microgel (B) is based on rubber.
[0074] In a preferred embodiment of the composition according to
the invention, the microgel (B) is modified by functional groups
reactive toward C.dbd.C double bonds.
[0075] In a preferred embodiment, the microgel (B) has a swelling
index from 1 to 15 in toluene at 23.degree. C.
[0076] The composition according to the invention preferably has a
viscosity from 2 mPas up to 50,000,000 mPas, preferably 50 mPas up
to 3,000,000 mPas, at a speed of rotation of 5 s.sup.-1, measured
using a cone-and-plate viscometer to DIN 53018 at 20.degree. C.
Organic Non-Crosslinkable Medium (A)
[0077] The composition according to the invention may contain one
or more organic media (A) having a viscosity of less than 30,000
mPas, more preferably of less than 1,000 mPas, more preferably of
less than 200 mPas, more preferably of less than 100 mPas, even
more preferably of less than 20 mPas at a temperature of
120.degree. C.
[0078] A medium of this type is preferably in a liquid to solid,
preferably liquid to free-flowing state at ambient temperature
(20.degree. C.).
[0079] The term "organic medium", as used in the present invention,
refers to a medium containing at least one carbon atom.
[0080] The term "non-crosslinkable media", as used in the present
invention, refers, in particular, to media of the type not
containing any groups that are crosslinkable via
heteroatom-containing functional groups or C.dbd.C groups such as,
in particular, conventional monomers or prepolymers that are
crosslinked or polymerised, in the conventional manner, radically,
with UV radiation, thermally and/or by polyaddition or
polycondensation, crosslinking agents (for example polyisocyanates,
polyamines, acid anhydrides, etc.) being added and oligomers or
polymers being formed. According to the invention, organic,
non-crosslinkable media used may also be media that contain, for
example, specific fractions of unsaturated bonds (specific
polyester oils, rape-seed oil, etc.) or hydroxy groups (polyether),
but are not crosslinked or polymerised in the conventional manner
to form oligomers or polymers. The non-crosslinkable media are
also, in particular, solvents, especially solvents to DIN 55
945.
[0081] Preferred are non-reactive solvents to DIN 55 945 such as
hexane, special boiling-point spirits, petroleum spirits, xylene,
solvent naphtha, balsam turpentine, methyl ethyl ketone, methyl
isobutyl ketone, methylamyl ketone, isophorone, butyl acetate,
1-methoxy propyl acetate, butyl glycol acetate, ethyl diglycol
acetate and N-methyl pyrrolidone (Brock, Thomas, Groteklaes,
Michael, Mischke, Peter, Lehrbuch der Lacktechnologie, Curt R.
Vincentz Verlag, Hanover, (1998) 93ff).
[0082] Particularly preferred non-crosslinkable media include:
polyether, for example Baylube 68CL, naphthenic oils, for example
Nynas T 110, paraffinic, highly refined mineral oils, for example
Shell Catenex S 932, ester oils, for example methyl ester SU, oils
based on renewable raw materials, for example refined rape-seed
oil. Particularly preferred non-crosslinkable media (A) include the
main class of hydrocarbons such as, for example, poly-alpha
olefins, hydrocrack oils, hydrotreated oils, etc., the polyether
oils, and the solvents to DIN 55 945.
[0083] In a preferred embodiment, the composition according to the
invention does not contain component (A).
[0084] In a further preferred embodiment, the composition according
to the invention consists only of components (B) and (C).
Functional Additives (C)
[0085] The term "functional additives (C)", as used in the present
application, refers to all substances that are added in small
quantities to other substances or substance mixtures in order to
alter in a desirable manner their characteristics or to facilitate
their processability. Such additives are in particular, but not
exclusively organic compounds comprising functional groups.
[0086] Preferably, the functional additive (C) is at least one
compound containing at least one heteroatom, preferably at least
two heteroatoms, selected from the group consisting of sulphur,
phosphorus, nitrogen, halogen and oxygen.
[0087] The functional additive (C) is preferably a compound
selected from the group consisting of: compounds suitable as
high-pressure additives such as organic polysulphides based on
sulphurized olefins, organic polysulphides based on sulphurized
triglycerides, fatty acid esters, fatty alcohols, etc. organic
polysulphides based on sulphurized oils; other sulphur-containing
compounds such as xanthogenates, thiourea derivatives, etc.;
organic chlorine compounds such as, for example, chlorinated
paraffins, etc.; organic nitrogen compounds such as, for example,
carbamic acid esters, etc.; compounds suitable as antiwear
additives such as phosphorus-containing compounds, for example
phosphoric acid esters, phosphonates, alkyl aryl phosphines,
phosphites, etc.; phosphorus- and sulphur-containing derivatives
such as, for example, metal dialkyl dithiophosphates, diaryl and
dialkyl dithiophosphates, monoalkyl and monoaryl dithiophosphates,
etc.; phosphorus- and nitrogen-containing compounds such as, for
example, amine-neutralised phosphoric acid derivatives, etc.;
phosphorus- and chlorine-containing compounds such as, for example,
chlorine-containing phosphorus compounds; compounds suitable as
antiwear additives such as, for example, neutralised alkali salts
and alkaline-earth salts of sulphonic acids and the derivatives
thereof such as, for example, esters, etc.; neutralised
monocarboxylic and dicarboxylic acids such as, for example,
naphthenic acid, salicylic acid, etc. and the derivatives thereof
such as, for example, alkali and alkaline-earth salts, esters,
amides, etc.; fatty oil and fatty acid derivatives; compounds
suitable as non-ferrous metal inhibitors such as triazole
derivatives, for example, benzotriazole, thiadiazole derivatives
such as, for example, dimercaptothiadiazoles, etc.; compounds
suitable as antioxidants such as alkyl/aryl-substituted phenol
derivatives, alkyl/aryl-substituted amine derivatives; other
phosphorus or sulphur-containing phenol/amine derivatives;
compounds suitable as friction modifiers such as metal-containing
organic compounds such as, for example, molybdenum, antimony,
dithiocarbamates or dithiophosphates, etc.; fatty acid or fatty
alcohol derivatives such as, for example, fatty acid amides,
polyolesters, phthalates, sebacates, benzoates, adipates, etc.;
compounds suitable as surface-active substances such as detergents,
for example alkyl/aryl fatty acid derivatives, alkyl/aryl sulphonic
acid derivatives, alkyl phenol derivatives, etc.; compounds
suitable as dispersing agents such as, for example, esterification
products of dicarboxylic acids and glycols, etc.; also pour-point
depressants, viscosity index improvers, defoaming agents,
deaerators, flow control agents, tackifiers, etc.; compounds
suitable as catalysts such as, for example, accelerators such as,
for example, mercaptobenzothiadiazole derivatives, etc., compounds
suitable as crosslinking agents such as, for example, urea,
triazine, carbamic acid derivatives, etc.
[0088] Component (C) is particularly preferably one of the
following compounds: compounds suitable as high-pressure additives
such as organic polysulphides based on sulphurized olefins, organic
polysulphides based on sulphurized triglycerides, fatty acid
esters, fatty alcohols, etc., organic polysulphides based on
sulphurized oils; organic chlorine compounds such as, for example,
chlorinated paraffins, etc.; organic nitrogen compounds such as,
for example, carbamic acid esters, etc.; compounds suitable as
antiwear additives such as phosphorus-containing components, for
example phosphonates, phosphites, etc.; phosphorus and
sulphur-containing derivatives such as, for example, metal dialkyl
dithiophosphates, diaryl and dialkyl dithiophosphates, etc.;
phosphorus- and nitrogen-containing compounds such as, for example,
amine-neutralised phosphoric acid derivatives, etc.; compounds
suitable as antiwear additives such as, for example, neutralised
alkali salts and alkaline-earth salts of sulphonic acids and the
derivatives thereof such as, for example, esters, etc. neutralised
monocarboxylic and dicarboxylic acids such as, for example,
naphthenic acid, salicylic acid, etc. and the derivatives thereof
such as, for example, alkali and alkaline-earth salts, esters,
amides, etc.; fatty oil and fatty acid derivatives; compounds
suitable as non-ferrous metal inhibitors such as triazole
derivatives, for example, benzotriazole, thiadiazole derivatives
such as, for example, dimercaptothiadiazoles, etc.; compounds
suitable as antioxidants such as alkyl/aryl-substituted phenol
derivatives, alkyl/aryl-substituted amine derivatives; compounds
suitable as friction modifiers such as metal-containing organic
compounds such as, for example, molybdenum, antimony,
dithiocarbamates or dithiophosphates, etc.; fatty acid or fatty
alcohol derivatives such as, for example, fatty acid amides,
phthalates, sebacates, adipates, etc.; compounds suitable as
surface-active substances such as detergents such as, for example,
alkyl/aryl sulphonic acid derivatives, alkyl phenol derivatives,
etc.; compounds suitable as dispersing agents such as, for example,
esterification products of dicarboxylic acids and glycols, etc.;
also defoaming agents, deaerators, flow control agents, tackifiers,
etc.; compounds suitable as catalysts such as, for example,
accelerators such as, for example mercaptobenzothiadiazole
derivatives, etc., compounds suitable as crosslinking agents such
as, for example, carbamic acid derivatives, etc.
[0089] The functional additive (C) preferably has a viscosity of
less than 1,000 mPas at a temperature of 120.degree. C.
Particularly preferably, it is in a liquid or free-flowing state at
ambient temperature.
[0090] The composition according to the invention preferably
contains 0.5 to 99.9% by weight, more preferably 10 to 90% by
weight, even more preferably 20 to 70% by weight, of the microgel
(B), based on the total quantity of the composition, wherein each
of the aforementioned upper and lower limits may also be
independent of one another.
[0091] The composition according to the invention also preferably
contains 0.1 to 99.5% by weight, more preferably 10 to 90% by
weight, more preferably 30 to 80% by weight, more preferably 40 to
97% by weight, even more preferably 50 to 95% by weight, even more
preferably 60 to 90% by weight, of the functional additive (C),
wherein each of the aforementioned upper and lower limits may also
be independent of one another.
[0092] The composition according to the invention preferably
consists of the microgel (B) and the functional additive. The
presence of water is, in particular, not preferred. The
compositions according to the invention preferably contain less
than 0.8% by weight, even more preferably less than 0.5% by weight,
of water. Most preferably, the presence of water is ruled out
(<0.1% by weight).
[0093] The composition according to the invention may contain one,
two, three or more of the functional additives. According to the
invention, what are known as additive packets, which contain more
than one functional additive bound or absorbed by the microgel (B),
in particular, are preferred.
[0094] The composition according to the invention may also contain
pigments and fillers such as inorganic and organic pigments,
siliceous fillers such as kaolin, talc, carbonates such as calcium
carbonate and dolomite, barium sulphate, metal oxides such as zinc
oxide, calcium oxide, magnesium oxide, aluminium oxide, highly
disperse silicas (precipitated and thermally prepared silicas),
metal hydroxides such as aluminium hydroxide and magnesium
hydroxide, glass fibres and glass-fibre products (slats, strands or
glass micro-beads), carbon fibres, thermoplastic fibres (polyamide,
polyester, aramide), rubber gels based on polychloroprene and/or
polybutadiene or else any other of the above-described gel
particles having a high degree of crosslinking and a particle size
from 5 to 1,000 nm.
[0095] The aforementioned fillers may be used individually or in a
mixture. In a preferred embodiment, the composition according to
the invention is prepared by mixing at least one functional
additive (C), in particular one having a viscosity of less than
30,000 mPas at a temperature of 120.degree. C., and at least one
dry microgel powder (B) (preferably less than 1% by weight, even
more preferably less than 0.5% by weight, of volatile fractions (no
microgel latices are used when mixing the components (A) and (B)),
using a homogeniser, a bead mill, a triple roller, a single or
multiple extruder screw, a kneader and/or a dissolver, preferably
using a homogeniser, a bead mill or a triple roller.
[0096] As far as the viscosity of the composition to be prepared is
concerned, the kneader, in which only very highly viscous (almost
solid to solid) compositions may preferably be used, is the most
limited option, i.e. it may be used only in special cases.
[0097] The drawbacks of the bead mill are the comparatively limited
viscosity range (usually low-viscosity compositions), the high
degree of effort required for cleaning it, the complex exchange of
product of the compositions that may be used, and also the wear to
the balls and grinding equipment.
[0098] Particularly preferably, the compositions according to the
invention are homogenised by a homogeniser or a triple roller. The
drawbacks of the triple roller are the comparatively limited
viscosity range (usually very high-viscosity compositions), the low
throughput and unenclosed mode of operation (poor protection during
operation). Very preferably, the compositions according to the
invention are therefore homogenised by a homogeniser. The
homogeniser allows low-viscosity and high-viscosity compositions to
be processed at a high throughput (high degree of flexibility).
Exchanges of product are comparatively rapid and simple.
[0099] The microgels (B) may be dispersed in liquid additives in a
surprising and novel manner. The fact that even the primary
particles could be dispersed is particularly surprising.
[0100] The microgels (B) are dispersed in liquid additives (C) in
the homogenising valve in the homogeniser (see FIG. 1).
[0101] In the process preferably used according to the invention,
agglomerates are broken down into aggregates and/or primary
particles. Agglomerates are physically separable units, during the
dispersion of which the primary particle size remains
unaltered.
[0102] FIG. 1 shows the mode of operation of the homogeniser
valve.
[0103] In the diagram, the terms used are: [0104] "basic product",
[0105] "valve seat", [0106] "valve" and [0107] "homogenised
product".
[0108] The product to be homogenised enters the homogenising valve
at a slow speed and is accelerated to high speeds in the
homogenising gap. Dispersion takes place after the gap principally
as a result of turbulence and cavitation (William D. Pandolfe,
Peder Baekgaard, Marketing Bulletin of the APV Homogeniser
Group--"High-pressure Homogenisers: Processes, Product and
Applications").
[0109] The temperature of the composition according to the
invention, on entering the homogeniser, is expediently
-40-140.degree. C., preferably 20-80.degree. C.
[0110] The composition according to the invention to be homogenised
is expediently homogenised in the device at a pressure from 20 to
4,000 bar, preferably 100 to 4,000 bar, preferably 200 to 4,000
bar, preferably 200 to 2,000 bar, very preferably 500 to 1,500 bar.
The number of cycles is determined by the desired dispersion
quality and may vary between one and 20, preferably between one and
ten, more preferably between one and four, cycles.
[0111] The compositions prepared according to the invention
accordingly have a particularly fine particle distribution, which
is achieved, in particular, using the homogeniser, which is also
extremely advantageous in terms of the flexibility of the process
with regard to varying viscosities of the liquid additives and the
resultant compositions, and necessary temperatures, and also in
terms of the quality of dispersion.
[0112] The invention further relates to the use of the composition
according to the invention for the preparation of
microgel-containing polymers or plastics materials.
[0113] The invention will be described in greater detail with
reference to the following examples. The invention is, of course,
not restricted to these examples.
EXAMPLE
[0114] The following additive/microgel combinations according to
the invention were prepared and then incorporated into a
lubricating oil.
[0115] A combination of additive and microgel in mineral oil was
tested both in comparison to pure mineral oil and in comparison to
mixtures of the individual additive in mineral oil or of the
microgel in mineral oil. A dispersing agent promoting stabilisation
was added to the microgel.
[0116] Typical characteristics of the stress and wear behaviour of
lubricants were tested to DIN 51350 in what is known as the
four-ball tester. The description of the test equipment and of the
tests carried out may be inferred from DIN 51350, Part 1 to Part 3.
The load limit up to the point of fusion--known as the fusion
load--was determined in N in accordance with DIN 51350, Part 2.
[0117] The wear characteristic--known as the cap diameter--was
determined in mm in accordance with DIN 51350, Part 3.
Results:
[0118] Whereas the additive/mineral oil combination results in an
improved fusion load compared to the mineral oil, without
significantly affecting the cap diameter, the microgel/stabilising
dispersing agent combination results in a significant improvement
in the cap diameter compared to the mineral oil, without
significantly reducing the fusion load.
[0119] Finally, the combination of additive, microgel/stabilising
dispersing agent and mineral oil results in a significant
improvement in both variables compared to the mineral oil, i.e. the
fusion load is increased and the cap diameter decreased.
TABLE-US-00001 Composition Mixture 1 Mixture 3 2% additive, 0.66%
Base medium Mixture 2 0.66% microgel, 1% microgel/1% dispersing
Pure 2% additive, dispersing agent, agent, 96.37% mineral oil
mineral oil 98% mineral oil 98.37% mineral oil Four-ball tester,
4,600 N 800 N 3,000 N 1,400 N fusion load [DIN 51350, Part 2]
Four-ball tester, cap 0.63 mm 0.68 mm 0.70 mm 0.50 mm [DIN 51350,
Part 3], 1 hour/1,500 rpm/300 N
CONCLUSION
[0120] The tests demonstrate a synergistic effect of the
microgel/additive combination used. It is believed that by adding
the microgel, the additive may be bound partly at the surface,
partly by diffusion in a kind of top structure. On the one hand, it
seems that the additive may have a more targeted effect in mixtures
during the measuring process either as a result of homogeneous
incorporation or as a result of slow release.
[0121] In lubricants, in particular, mainly fats and pastes, but
also solutions, the additive/microgel combinations according to the
invention are capable of achieving a more efficient effect for a
lubricant, for example, by means of a targeted release of additive.
The combinations are notable for significantly simpler handling of
the fat/pastes compared to the individual components, liquid
additive and microgel powder. In the case of lubricating greases,
in particular, combinations of this type are able to prevent the
loss in consistency that otherwise occurs in fats when liquid
additives are added.
* * * * *