U.S. patent application number 10/354665 was filed with the patent office on 2003-07-24 for rubber mixtures for roller coatings.
Invention is credited to Fuchs, Erich.
Application Number | 20030139493 10/354665 |
Document ID | / |
Family ID | 7921130 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030139493 |
Kind Code |
A1 |
Fuchs, Erich |
July 24, 2003 |
Rubber mixtures for roller coatings
Abstract
This invention relates to a rubber mixture containing a nitrile
rubber, a metal salt of an acrylate, a liquid acrylate and
optionally other additives, a process for its preparation, and use
for all types of molded articles, in particular roller
coatings.
Inventors: |
Fuchs, Erich; (Leverkusen,
DE) |
Correspondence
Address: |
BAYER POLYMERS LLC
100 BAYER ROAD
PITTSBURGH
PA
15205
US
|
Family ID: |
7921130 |
Appl. No.: |
10/354665 |
Filed: |
January 30, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10354665 |
Jan 30, 2003 |
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09653972 |
Sep 1, 2000 |
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6538071 |
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Current U.S.
Class: |
523/202 ;
524/492; 524/495; 525/244; 525/274 |
Current CPC
Class: |
C08K 5/098 20130101;
C08L 15/005 20130101; C08L 9/02 20130101; C08K 5/098 20130101; F16C
13/00 20130101; C08K 5/098 20130101 |
Class at
Publication: |
523/202 ;
524/492; 524/495; 525/244; 525/274 |
International
Class: |
C08G 002/00; C08F
257/00; C08K 003/04; C08K 003/34 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 7, 1999 |
DE |
19942743.7 |
Claims
What is claimed is:
1. A rubber mixture comprising: a) at least one nitrile rubber; b)
at least one metal salt of an acrylate; c) at least one liquid
acrylate, optionally applied to a carrier, and d) optionally other
additives and/or fillers.
2. A rubber mixture according to claim 1, wherein said at least one
nitrile rubber is selected from the group consisting of NBR,
partially hydrogenated NBR and completely hydrogenated NBR or
mixtures of two or more of these.
3. A rubber mixture according to claim 1, wherein said at least one
metal salt of an acrylate is a zinc diacrylate or a zinc
dimethylacrylate or a mixture.
4. A rubber mixture according to claim 1, wherein the liquid
acrylate is butanediol dimethacrylate or trimethylolpropane
trimethacrylate or a mixture.
5. A rubber mixture according to claim 1, wherein said rubber
mixture also contains a siliceous filler, carbon black, zinc oxide,
magnesium oxide or a mixture of two or more of these components. A
rubber mixture according to claim 1, wherein said rubber mixture
contains vulcanization retarders and/or vulcanization accelerators.
A cross-linkable rubber mixture comprising a rubber mixture,
wherein said rubber mixture comprises: a) at least one nitrile
rubber; b) at least one metal salt of an acrylate; c) at least one
liquid acrylate, optionally applied to a support, and d) optionally
other additives and/or fillers.
8. A crosslinkable rubber mixture according to claim 7 wherein said
at least one nitrile rubber is selected from the group consisting
of NBR, partially hydrogenated NBR and completely hydrogenated NBR
or mixtures of two or more of these.
9. A crosslinkable rubber mixture according to claim 7, wherein
said at least one metal salt of an acrylate is a zinc diacrylate or
a zinc dimethylacrylate or a mixture.
10. A crosslinkable rubber mixture according to claim 7, wherein
the liquid acrylate is butanediol dimethacrylate or
trimethylolpropane trimethacrylate or a mixture.
11. A crosslinkable rubber mixture according to claim 7, wherein
said rubber mixture also contains a siliceous filler, carbon black,
zinc oxide, magnesium oxide or a mixture of two or more of these
components.
12. A crosslinkable rubber mixture according to claim 7, wherein
said rubber mixture contains vulcanization retarders and/or
vulcanization accelerators.
13. A process for the preparation of a rubber mixture comprising
the step of mixing in a mixing unit: a) at least one nitrile
rubber; b) at least one metal salt of an acrylate; c) at least one
liquid acrylate,, optionally applied to a carriers and d)
optionally other additives and/or fillers.
14. A process according to claim 13, wherein said mixture is
crosslinked.
15. A process according to claim 14, wherein said mixture is
crosslinked with a peroxide.
16. A molded article comprising a rubber mixture comprising a) at
least one nitrile rubber; b) at least one metal salt of an
acrylate; c) at least one liquid acrylate, optionally applied to a
carrier, and d) optionally other additives and/or fillers.
17. A coating for a roller comprising a rubber mixture comprising:
a) at least one nitrile rubber; b) at least one metal salt of an
acrylate; c) at least one liquid, acrylate, optionally applied to a
support and d) optionally other additives and/or fillers.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a rubber mixture containing a
nitrile rubber, a metal salt of an acrylate, a liquid acrylate and
optionally other additives, a process for its preparation, and use
for all types of molded articles, in particular roller
coatings.
BACKGROUND OF THE INVENTION
[0002] Rollers having a rubber coating are used in many fields,
including the print and textile industry, in machines, such as, for
example, fax machines and in the steel industry and paper
industry.
[0003] Roller coatings are subjected to extreme stresses,
particularly in the steel and paper industries. In such
applications, the coatings are required to have a combination of
the following properties:
[0004] low compression set;
[0005] low abrasion;
[0006] little swelling in the media used;
[0007] good resistance to heat and chemicals;
[0008] excellent adhesion to the metal surface under the coating;
and/or
[0009] low build-up of heat under stress.
SUMMARY OF THE INVENTION
[0010] It has now been found that a rubber mixture which contains a
nitrile rubber and, in addition, a metal salt of an acrylate and a
liquid acrylate is particularly suitable as raw material for rubber
coatings for rollers.
[0011] This application accordingly provides a rubber mixture,
containing
[0012] a) one or more nitrite rubbers
[0013] b) one or more metal salts of an acrylate
[0014] c) one or more liquid acrylates, optionally applied to a
carrier, and
[0015] d) optionally other additives and/or fillers.
[0016] Nitrite rubbers are meant to be diene-(meth)acrylonitrile
copolymers. The preferred dienes here are isoprene and, in
particular, butadiene. The copolymers have a content of
copolymerized acrylonitrile units and/or methacrylonitrile units of
5 to 60 wt. %, preferably 10 to 50 wt. %.
[0017] Moreover, the term explicitly includes hydrogenated nitrite
rubbers. According to this invention, "hydrogenated nitrite rubber"
or "HNBR" means nitrite rubbers, the C.dbd.C double bonds of which
are selectively (that is, without hydrogenation of the C.ident.N
triple bond) partially or completely hydrogenated. Preferred
hydrogenated nitrile rubbers are those having a degree of
hydrogenation, based on the C.dbd.C double bonds originating from
the butadiene, of at least 75%, preferably of at least 95%, in
particular of at least 98%. The degree of hydrogenation can be
determined by NMR spectroscopy and IR spectroscopy.
[0018] The hydrogenation of nitrite rubber is known: U.S. Pat. No.
3,700,637, DE-A 2,539,132, DE-A 3,046,008, DE-A 3,046,251, DE-A
3,227,650, DE-A 3,329,974, EP-A 111,412, FR-B 2,540,503.
Hydrogenated nitrite rubbers are distinguished by having high
tensile strength, low abrasion, low residual deformation after
compressive stress and tensile load and good resistance to oil, but
primarily by a notable resistance to thermal and oxidative
influences. Accordingly, hydrogenated nitrite rubbers are preferred
in this invention.
[0019] Suitable nitrite rubbers generally have Mooney viscosities
(DIN 53 523, ML 1+4) of 25 to 100 Mooney units, in particular 40 to
80 Mooney units.
[0020] The addition of metal salts of an acrylate to mixtures
containing nitrile rubbers is known. Suitable acrylates may be
unsubstituted or substituted. Methacrylates are an example of
substituted acrylates.
[0021] The person skilled in the art knows of suitable acrylates
from EP-A1 0,319,320, in particular page 3, lines 16 to 35; from
U.S. Pat. No. 5,208,294, in particular column 2, lines 25 to 40 and
from U.S. Pat. No. 4,983,678, in particular column 2, lines 45 to
62. Zinc acrylate, zinc diacrylate and zinc dimethylacrylate, in
particular, are mentioned there.
[0022] It may be advantageous to use the metal salt of the acrylate
together with a scorch retarder. Suitable examples here are
hindered phenols, such as methyl-substituted aminoalkylophenols, in
particular 2,6-ditert.-butyl-4-(dimethylamino)phenol.
[0023] The liquid acrylate may be any acrylate which is known to
the person skilled in the art and is in liquid form at room
temperature.
[0024] Trimethylolpropane trimethacrylate (TRIM), butanediol
dimethacrylate (BDMA) and ethylene glycol dimethacrylate (EDMA) are
particularly preferred.
[0025] In order to achieve an improved incorporation, it may be
advantageous to use the liquid acrylate bound to a carrier.
Examples of suitable carriers are silicates, precipitated silicas,
clays, carbon black, talc or polymers. In general, mixtures
containing 5 to 50 wt. % carrier are used.
[0026] Other suitable additives include those known to the person
skilled in the art, for example, vulcanization activators, in
particular metal oxides, such as zinc oxide or magnesium oxide,
antidegradants, such as alkyl-substituted diphenylamines,
mercaptobenzimidazoles, unsaturated ethers, such as Vulkazon.RTM.
AFD (Bayer AG, D) or cyclic, unsaturated acetals, such as
Vulkazon.RTM. AFS/LG (Bayer AG, D). The following may also be
mentioned as additives:
[0027] plasticizers, in particular carboxylic esters, as well as
sebacic acid and its derivatives or trimellitic acid and its
derivatives
[0028] processing aids, in particular stearic acid and its
derivatives, such as zinc stearate, or polymers, such as
poly(ethylene vinyl acetate) (Levapren.RTM. from Bayer AG, D) or
poly(ethylene vinyl acrylate)VAMAC.RTM. from DuPont).
[0029] It may also be advantageous to introduce fillers into the
rubber mixture according to the present invention. These may be
non-reinforcing or reinforcing.
[0030] Examples of fillers which may be mentioned are:
[0031] carbon blacks, such as MT, GPF, SRF blacks and primarily FEF
blacks;
[0032] metal oxides, such as titanium dioxide (primarily as white
pigment);
[0033] silicates, such as sodium aluminium silicate;
[0034] silicas, in particular precipitated silicas;
[0035] To improve the abrasion, so-called active fillers in
accordance with the DIN 66131 are preferred, published, for
example, on page 535 of "Handbuch fur die Gummiindustrie", Bayer
AG, 1992, Leverkusen.
[0036] Clays, mica, talc.
[0037] In addition, it may be advantageous to use extra activators
in order to improve the adhesion between filler and rubber, such
as, for example, silanes, such as Silquest.RTM. RC-1 (Union
Carbide, US). Pigments may also be added.
[0038] The quantities of the individual components of the mixture
depend on the intended use of the mixture and can be determined by
a few preliminary tests.
[0039] The materials are generally used in the following quantities
(in each case, in phr=per hundred parts of rubber):
[0040] metal salt of an acrylate: 10 to 120 phr, preferably 10 to
85 phr, most preferably, 20 to 65 phr,
[0041] liquid acrylate: 5 to 80 phr, preferably 20 to 60 phr, in
each case calculated without carrier,
[0042] antidegradant: 0 to 4 phr,
[0043] retarder: 0 to 2 phr,
[0044] metal oxides, such as ZnO: 0 to 30 phr,
[0045] fillers: 0 to 150 phr, preferably active fillers,
[0046] plasticizer: 0 to 20 phr,
[0047] processing aids: 0 to 2 phr.
[0048] The invention also provides crosslinkable mixtures
containing the rubber mixtures according to the present invention,
as well as a process for the preparation of the rubber mixtures
according to the present invention and of cross-linkable rubber
mixtures, characterized in that the components are mixed in a
mixing unit.
[0049] In order to produce crosslinkable mixtures from the mixtures
according to the present invention, crosslinking agents are added
to the rubber mixtures according to the present invention. Peroxide
systems are suitable crosslinking agents.
[0050] Preferred peroxide systems include dialkyl peroxides, ketal
peroxides, aralkyl peroxides, peroxide ethers, peroxide esters,
such as, for example: di-tert.-butyl peroxide,
bis(tert.-butylperoxyisopropyl)benz- ene, dicumyl peroxide,
2,5-dimethyl-2,5-di(tert.-butylperoxy)hexane,
2,5-dimethyl-2,5-di(tert.-butylperoxy)-3-hexene,
1,1-bis(tert.-butylperox- y)-3,3,5-trimethylcyclohexane, benzoyl
peroxide, tert.-butyl cumyl peroxide and tert.-butyl
perbenzoate.
[0051] The quantities of peroxide are within the range of 1 to 10
phr, preferably within the range of 4 to 8 phr, based on rubber.
The cross-linking can be effected at temperatures of 100.degree. C.
to 200.degree. C., preferably 130.degree. C. to 180.degree. C.,
optionally at a pressure of 10 to 200 bar. Subsequent to the
crosslinking, the vulcanizates can be post-cured by being stored at
elevated temperature.
[0052] The peroxides can advantageously also be used in
polymer-bound form. Appropriate systems are commercially available,
for example, Poly-Dispersion.RTM. T (VC) D-40 P from Rhein Chemie
Rheinau GmbH, D (=polymer-bound
di-tert.-butylperoxyisopropylbenzene).
[0053] The crosslinking can also be achieved by high-energy
radiation.
[0054] Crosslinking according to the present invention means that
less than 10 wt. %, preferably less than 5 wt. %, based on rubber,
is extractable during extraction for 10 hours in a Soxhlet
attachment with toluene as extracting agent.
[0055] The optimal quantity of crosslinking agent is easily
determined by preliminary experiments.
[0056] Any apparatus for mixing rubbers which is known to the
person skilled in the art may be used as the mixing apparatus, in
particular internal mixer, open mills and screw-type machines.
[0057] Here, care should be taken to ensure that the rubber is not
degraded during the mixing procedure. It may be advantageous to
cool the mixture during the mixing procedure. In order to avoid
scorch, the peroxide is frequently added as the last component,
optionally in a separate mixing procedure.
[0058] The invention also provides the use of the rubber mixtures
according to the present invention for the production of all types
of molded articles, in particular coatings for rollers, most
particularly rollers for the paper, textiles, printing and steel
industries.
[0059] Rollers generally consist of a metal core having a variable
diameter, metal cores with a diameter of 1 to 5 m being preferred.
The metal core generally consists of steel of various compositions,
onto which the crosslinkable rubber mixture is drawn by means of
conventional prior art methods and subsequently cross-linked. A
good adhesion of coating to metal and inside the coating is crucial
here. It may be advantageous to improve the adhesion of coating to
metal by means of adhesion promoters, such as dispersions/solutions
of halogenated polymers, optionally with crosslinking
agents/fillers/pigments. These substances are commercially
available.
[0060] The rubber mixtures according to the present invention are
particularly suitable for use on rollers, as in the crosslinked
condition they combine an excellent hardness in the range above 20
Shore D (DIN 53 505), even at elevated service temperatures, with a
good resistance to abrasion, heat, water and chemicals. This
balanced range of properties is not achieved in prior art. The
rubber mixtures according to the present invention are, of course,
also suitable for the production of other molded articles, such as
profiles, belts, rings, seals, damping elements, etc.
[0061] Accordingly, molded articles, in particular rollers and
belts, obtainable using a rubber mixture according to the present
invention are also provided by the invention.
[0062] To the person skilled in the art, it is a trivial matter to
modify specifically the properties of the mixtures according to the
present invention by adding other polymers, such as BR, NR, IIR,
IR, EPDM, EPM, CR, SBR, AEM, ACM or fluoropolymers.
[0063] The following Examples are intended to illustrate the
invention, without thereby limiting it.
EXAMPLES
A. Methods of Measurement
[0064]
1 Residual double-bond content IR spectroscopy Mooney viscosity
ASTM D 1646 (ML 1 + 4 (100.degree. C.)) (given in Mooney units)
Volatile constituents (wt. %) ASTM D 1416 Ash content (wt. %) ASTM
D 1416 Acrylonitrile (ACN) content in accordance with the (wt. %
bound in the polymer) instructions below.
B. Brief Description of the Method
[0065] In the analysis, the rubber is pyrolyzed at 900.degree. C.
on a catalyst in a stream of oxygen. The unused oxygen is absorbed
on a copper reduction reactor and the NO.sub.x gases formed are
reduced to nitrogen. Then the CO.sub.2 present in the stream of
sample gas is withdrawn in an Na.sub.2CO.sub.3/NaOH trap and the
water present in the stream of sample gas is withdrawn in an
MgClO.sub.4 trap. The change in the thermal conductivity of the
stream of sample gas compared with the stream of carrier gas is a
measure of the nitrogen content of the sample.
C. Equipment
[0066] Protein analyzer, product of Fisons, Model NA 2000
[0067] Microbalance, product of Sartorius, Model Micro
[0068] Analytical unit, product of Digital, Model DECpc Lpx 433 dx,
with interfaces to the NA 2000 and balance interface, and the
software EAGER 200
D. Chemicals and Solvents
[0069] Methionine, product of Hekatech
E. Constituents of Formulation
[0070]
2 Therban .RTM. C 3467 Bayer AG HNBR with 5.5% RDB 34% ACN, 68
Mooney units Zinkoxyd Aktiv Bayer AG active zinc oxide Scorchguard
.RTM. O Rhein Chemie Rheinau magnesium oxide paste GmbH Naugard 445
Uniroyal subst. diphenylamine Vulkanox .RTM. ZMB 2 Bayer AG zinc
methylmercapto- benzimidazole Tronox .RTM. R-UF Kerr-McGee Pigments
titanium dioxide, rutile GmbH & Co. KG type Vulkasil .RTM. S
Bayer AG precipitate silica Vulkasil .RTM. A 1 Bayer AG sodium
aluminum silicate Sartomer SR633 Sartomer zinc diacrylate with
retarder additive TRIM SR-350 Sartomer trimethylolpropane
trimethacrylate Rhenofit .RTM. TRIM/S Rhein Chemie Rheinau
trimethylolpropane GmbH trimethacrylate 70% bonded to silica 30%
BDMA ATM Ancomer butanediol dimethacrylate Ethanox 703 Albemarle,
BE 2,6-ditert.-butyl-4-(di- methylamino)phenol Poly-Dispersion
.RTM. Rhein Chemie Rheinau di(tert.-butylperoxy-iso- T (VC) D-40 P
GmbH propyl)benzene, poly- merically bonded
F. Preparation of the Mixtures
[0071] The mixtures were prepared in an internal mixer GK 1.5 E
product of Krupp Elasto-mertechnik, Hamburg). Cooling-water
temperature 50.degree. C.; rotor speed 50 rpm; ram pressure 6 bar;
proportion of internal mixer filled 70-80%, based on the volume of
the mixing compartment.
[0072] Mixing procedure: The rubber is placed in the internal
mixer. After an operating time of 1 minute, the remaining
constituents are added. The internal mixer emptied at a batch
temperature of >125.degree. C. The peroxide is subsequently
mixed on a roll mill (Krupp Elastomertechnik; diameter 200 mm,
working width 350 mm) at a cooling-water temperature of 40.degree.
C.
[0073] The sheets for the determination of the mechanical
properties were cross-linked/vulcanized under the stated
conditions, between Teflon sheets, in a vulcanizing press (Krupp
Elastomertechnik).
3 Properties: Value: Dimension Test Standard: ML-1 + 4/ Mooney
units Mooney viscosity DIN 53525 Part 3 100.degree. C.
MS-T5/120.degree., and min Mooney pre- DIN 53525 Part 4 140.degree.
C. vulcanization behavior (time for 5 Mooney units above minimum)
MDR rheometer S'd Nm Course of DIN 53529 Part 3 minimum, or
vulcanization. maximum or Torque- MAX - Min minimum- maximum or
difference max./min. T10, T50, T80, min Time for 10%, T90 50%, 80%,
90% of full cure F MPa Tensile strength DIN 53504 D % elongation at
DIN 53504 break S xxx MPa Tensile strength DIN 53504 at xxx %
elongation H Shore A/D Hardness DIN 53505 E % Rebound DIN 53512
resilience Abrasion cmm Abrasion DIN 53516 Compression set %
Compression set DIN 53517 Sample II Hot-air aging Aging in hot air
delta F, delta D, %, or Shore Change in tensile DIN 53508 delta H
A/D strength, elongation at break, hardness Distilled water
Immersion in distilled water delta F, delta D, %, or Shore D Change
in tensile, DIN 53521 delta H, delta G strength, elongation at
break, hardness weight
G. Testing of the Mixtures
Example 1
[0074]
4 Parts Example 1 Therban C 3467 100 Sartomer SR 633 60 Rhenofit
TRIM/S 57 Naugard 445 2 Poly-Dispersion T (VC) D-40 P 6 Ethanox 703
1 Properties of the mixtures ML-1 + 4/100.degree. C. (Mooney units)
24 120/140.degree. C. MS-T5/120.degree. C. (min) >45/>45 MDR
Rheometer 170.degree. C./ operating time 45 min MINIMUM (S'dNm) 0.3
MAXIMUM 160.4 MAX - MIN 160.1 T 10 (min) 3.5 T 50 6.8 T 80 11.6 T
90 15.2 Vulcanization 170.degree. C. (min) 17 F (MPa) 20.3 D (%)
110 S 20 (MPa) 12.8 S 50 (MPa) 15.9 S 100 (MPa) 20.5 H 23.degree.
C. (Sh. A) 97 H 23.degree. C. (Sh. D) 55 Vulcanization 170.degree.
C. (min) 23 Abrasion DIN 53516 (cmm) 63 Example 2 Therban C 3467
100 Zinkoxyd aktiv 2 Scorchguard O 2 Vulkasil S 20 Vinylsilane (1)
3 Naugard 445 2 Vulkanox ZMB-2 0.5 Tronox R-UF 3 Rhenofit TRIM/S 57
Sartomer SR 633 (3) 60 Ethanox 703 1 Poly-Dispersion T (VC) D-40 P
6 Properties of the mixture ML-1 + 4/100 C. (Mooney units) 37
MS-T5/135 C. (min) 43.2 MDR Rheometer 152.degree. C./ operating
time 180 min. MINIMUM (S'dNm) 0.9 MAXIMUM 195.7 MAX - MIN 194.9 T
10 (min) 8.7 T 50 11.4 T 80 14.4 T 90 16.2 Vulcanization 90 min
152.degree. C. F (MPa) 20.8 D (%) 46 S 20 (MPa) 17.3 S 50 (MPa)
21.3 S 100 (MPa) -- H 23.degree. C. (Sh. A) 99 H 23.degree. C. (Sh.
D) 69 Hot-air aging 21 d 100.degree. C. .DELTA. F (%) +22 .DELTA.D
(%) -20 .DELTA. U (Sh. D) +3 Distilled water 90.degree. C. .DELTA.
F (%) 7 d +1 14 d +1 .DELTA. D (%) 7 d +22 14 d +17 .DELTA. H (Sh.
A) 7 d -1 14 d -1 .DELTA. U (Sh. D) 7 d -7 14 d -9 .DELTA. G (%) 7
d +2.5 14 d +1.7 Vulcanization 180 min. 152.degree. C. Abrasion DIN
53516 (cmm) 129
[0075] 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.
* * * * *