CA2194652C - Peroxide-cured blends of polyacrylate and partially hydrogenated nitrile rubbers - Google Patents

Abstract

Blends of a polyacrylate elastomer with a partially hydrogenated rubber, when peroxide-cured, provide a product which is excellent in resistance to degradation by heat or contact with oil, and which is particularly suitable for making belts, hoses, gaskets and the like for use in automobile engines.

Description

~~9~652 PEROXIDE-CURED BLENDS OF POLYACRYLATE
AND PARTIALLY HYDROGENATED NITRILE RUBBERS
This invention relates to peroxide-curable blends of acrylate elastomers and partially hydrogenated nitrile rubbers, and to the blends which have been peroxide-cured. The cured blends exhibit excellent resistance to the degrading effects of oil and heat and are particularly useful as belts, hoses, seals, gaskets and the like in automobile engines.
Hackqround of the Invention Polyacrylates are elastomeric polymers or copolymers of acrylic acid esters having a saturated main chain with the ester groups constituting side chains on the main chain. Polyacrylates are resistant to ozone and to aging in air at moderately elevated temperatures up to about 200°C, and resist swelling, hardening, and other changes that take place when contacted with hot oils in an automobile engine.
Partially hydrogenated nitrile rubbers have excellent resistance to degradation when contacted by hot oils but are not as resistant to high temperatures as are polyacrylates. Unlike polyacrylates made by polymerizing mixtures of alkyl acrylate esters, partially hydrogenated nitrile rubbers contain carbon-carbon unsaturation and are readily peroxide-curable. Peroxide curing is advantageous in that a good cure is obtained with a minimum of scorch (premature crosslinking during cure?, and the cured product, where the polymer chains are crosslinked by carbon-carbon linkages, is generally more stable than a product obtained by vulcanization with nitrogen- or sulfur-containing compounds.
It is, therefore, an object of the present invention to provide a blend of elastomers which can be peroxide-cured to yield a cured product which is resistant to deterioration caused by exposure to both heat and oil.

2~ 94652 Brief Summary of the Invention It has now been discovered that the desirable properties of oil-resistance and high service temperature in a blend of elastomers can be realized in a peroxide-cured composition which comprises from 10 to 90 parts by weight of a particular polyacrylate elastomer and 90 to 10 parts by weight of a partially hydrogenated nitrite rubber.
Brief Description of the Invention In one composition aspect, the present invention is a peroxide-cured blend comprising:
10 to 90 parts by weight of a polyacrylate elastomer comprising at least 10 mole % of the structural unit --f-CHzCH~
C=O

wherein R1 is a C4_B alkyl group;
up to 30 mole % and preferably 20 to 30 mole % of the structural unit -(-CHZ CH-~-C=O

wherein R2 is an alkoxyalkyl group containing 2-12 carbon atoms;

~~946~2 and the balance to a total of 100 mole % of the structural unit -f-CHz CHI
C=O

wherein R3 is a Cl_3 alkyl group; and 90 to 10 parts by weight of a partially hydrogenated nitrile rubber having a degree of unsaturation of from 0.1 to 20%.
Particularly preferred are blends wherein the polyacrylate elastomer additionally contains 1 to 10% of structural units derived from acrylonitrile. Such polyacrylate elastomers comprise at least 10 mole % of the structural unit -~-CHZCH-~-C=O
2 0 ORi wherein Rl is a C4_8 alkyl group;
up to 30 mole % and preferably 20 to 30 mole % of the structural unit --E-CHZCH-~-C=O
3 0 . ORz wherein RZ is an alkoxylakyl group containing 2-12 carbon atoms;
1 to 20 mole % of the structural unit -~CHZCH-~-CN

2~ 94652 and the balance to a total of 100 mole % of the structural unit -~-CH2CH~
C=O

wherein R3 is a Cl_3 alkyl group .

The present invention also contemplates curable compositions comprising the above-described blends and containing a peroxide curing system, particularly a peroxide curing system comprising an organic peroxide and m-phenylenediamine biS-maleimide.
Detailed Description of the Invention The polyacrylate elastomers utilized in practicing the method of the present invention are copolymers formed by copolymerizing a mixture containing two alkyl acrylates and containing at least 10 mole % of a CQ_e acrylate, wherein the alkyl groups may be straight-chain or branched-chain alkyl groups such as isobutyl, n-pentyl, isoamyl, n-hexyl, 2-ethylhexyl and n-octyl, with n-butyl acrylate being preferred. The other alkyl acrylate monomer may be a C1_3 acrylate, such as methyl, ethyl or propyl acrylate, where the alkyl groups may be straight-chain or branched-chain alkyl groups; and/or an alkoxyalkyl group containing 2-12 carbon atoms, such as methoxyethyl, methoxymethyl, ethoxyethyl, butoxyethyl and ethoxypropyl and with methoxyethyl being preferred. Preferably, the mixture may contain 1 to 20 mole %, of structural units derived from acrylonitrile. These polyacrylates do not contain reactive sites, such as chlorine or an epoxy group in their side chains, characteristic of sulfur and nitrogen-vulcanizable polyacrylates.
Polyacrylate elastomers or rubbers are prepared by emulsion, suspension, solution or bulk polymerization. Emulsion and suspension polymerization are more commonly employed, and polymerization is generally initiated by free-radical generating agents. Methods for making polyacrylates are well known to those skilled in the art and are not part of the present invention.

~~ ~~.65~
The nitrile rubbers blended with t a polyacrylate elastomers are partially hydrogenated copolymers of 75-25 parts of 1,3-butadiene and 25-50 parts acrylonitrile having a degree of unsaturation of from 0.1 to 20a. Partially hydrogenated nitrile rubbers having a degree of unsaturation lower than O.lo are not readily peroxide curable. And those having a degree of unsaturation above 20% are less resistant to heat aging and to attack by ozone.
The curable blends of the present invention are cured by heating at 140-220°C for up to 30 minutes, preferably 4-10 minutes, with a peroxide-curing system containing a dialkyl peroxide such as di-1,1-bis(t-butylperoxy)-3,3,5 trimethylcyclohexane as the peroxide curing agent and m ph~n~l~nedl~mine bis-maleimide as the coagent or promoter. A
polyscrylate elastomer and hydrogenated nitrile rubber masterbatch is prepared in the customary manner and admixed with the curing system using conventional equipment, such as blenders, mixers, extruders or the like. The curable or vulcanizable composition, may contain, in addition to the curing system, a conventional lubricant such as stearic acid, a carbon black filler and an antioxidant. As is well known to those skilled in the art, compression set is an art-recognized measure of the extent of curing and is determined by compressing an article between flat plates for a specified time at the test temperature, after which the compressing force is released and the article allowed to recover for a specified period of time. The amount of unrecovered height, calculated as a percentage, is compression set.
Articles made from acrylic elastomer and hydrogenated nitrile rubber blends are processed in the same general manner as articles made from other elastomers, and can be shaped by compression, transfer or injection molding, with the latter being preferred. Articles made from conventionally vulcanized or cured polyacrylate parts are usually post-cured after primary curing because of the stringent requirements for articles to be used in 2~94~52 automotive applications. As shown by their compression set values, articles made from the peroxide-cured polyacrylates of the present invention do not require post-curing.
Our invention is further illustrated by means of the following non-limiting examples:
_Example 1 This example illustrates compositions comprising a variety of polyacrylate elastomers admixed with the same l0 partially hydrogenated nitrile rubber. (Example lA does not contain a polyacrylate rubber and is not a composition according to the present invention).
The curable compositions were prepared by mixing all components, except for the curing system, in a Banbury mixer. The curing system, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane and m-phenylenediamine bis-maleimide, and antioxidant when utilized, were added, and the compositions uniformly blended using the Bandury mixer. The components of the curable compositions, the times and temperatures of curing, processing properties during curing and the properties of the cured product, including the results of tests on aged products, are summarized below.

lA 1B 1C 1D lE 1F

Nitrile rubber 100.0 80.0 80.0 80.0 80.0 80.0 Polyacylate I 20.0 Polyacylate ii 20.0 Polyacylate III 20.0 Polyacylate IV 20.0 Polyacylate V 20.0 Carbon black 50.0 50.0 50.0 50.0 50.0 50.0 Magnesium oxide 5.0 5.0 5.0 5.0 5.0 5.0 1 Plasticizer 5.0 5.0 5.0 5.0 5.0 5.0 Amine antioxidant 1.5 1.5 1.5 1.5 1.5 1.5 2-mercaptolimidazone 0.5 0.5 0.5 0.5 0.5 0.5 Peroxide 8.0 8.0 8.0 8.0 8.0 8.0 Bis-maleimide 2.0 2.0 2.0 2.0 2.0 2.0 1 172.0 172.0 172.0 172.0 172.0 172.0 The nitrile rubber is a partially hydrogenated nitrile rubber containing about 36% of acrylonitrile having a degree of 20 unsaturation of about 40. Polyacrylate I contains about 55% by weight of structural units derived from ethyl acrylate and 45%
by weight of structural units derived from n-butyl acrylate.
Polyacrylates II-V contain about 6-23% by weight of structural units derived from ethyl acrylate, 47-62% by weight of structural 25 units derived from butyl acrylate, about 26-30% by weight of structural units derived from methoxyethyl acrylate and 4-9% by weight of structural units derived from acrylonitrile.
The processess properties of the curable compositions were measured using a Mooney Viscometer, large rotor, at 125°C, and 30 a rheometer oscillating disc using a microdie at 100 cpm, 3° arc at 190°C.

~194 E~52 lA 1B 1C 1D lE 1F

MOONEY VISCOMETER:

VISC. MINIMUM 58 45 47 47 47 45 T5, minutes 12.2 10.7 9.7 9.6 9.5 8.9 REHEOMBTER, MICRODIE

ML,lbfin 17.9 14.8 15.114.9 14.8 14.1 ML,Nm 2.0 1.6 1.7 1.6 1.6 1.6 MH,lbfin 121.0 91.7 98.298.2 100.096.0 1 ~ MH,Nm 13.4 10.2 10.910.9 11.1 10.7 Ts2, minutes 1.2 1.1 1.1 1.1 1.1 1.0 T90, minutes 13.0 11.9 11.511.3 11.6 11.8 CURE RATE 11.8 10.8 10.210.5 10.5 10.8 Properties of the cured composition, 20 minutes cure time at 170°C with no post-cure, are as follows:
lA 1B 1C 1D 18 1F

2 0 STRESS 1001, psi 1175 945 1010 1060 1065 1045 STRESS 1001, MPs 8.1 6.5 7.0 7.3 7.3 7.2 TENSILE, pal 3990 3150 3240 3435 3490 3200 TENSILE, MPs 27.5 21.7 22.4 23.7 24.1 22.1 ELONGATION, ~ 255 240 235 250 260 230 2 5 HARDNESS, A pta 75 72 73 71 70 74 COMPRESION SET, METHOD
B, BUTTONS

3 0 70hrs ~ 150C 19 23 25 24 27 23 168hr8 O 150C 21 30 34 34 37 34 GEHMAN LOW TEMPERATURE
TORISON

TEST, ASTM D1053 ORIGINAL ANGLE TWIST

3 5 T2,C -20 -16 -16 -16 -15 -15 T5,C -30 -32 -33 -32 -32 -32 LOW TSMPBRATURB BRITTLBNESS, Tp, C -33 -2? -30 -30 -26 -36 Stability of the peroxide cured acrylates to oxidation was measured using accelerated aging tests in which dumbbells cut from the material to be tested were exposed to circulating hot air in an oven. Their stability, when exposed to hot oil, a 2~94~52 particularly important property from articles intended for automotive applications, was also measured. The results of aging the cured composition are summarized below:

~~ 94652 - H~A'1'1NU 1N H1K
UVk~t~

lA 1B 1C 1D lE 1F

70 hours at 150C

TENSILE, psi 4195 3195 3615 3465 3265 3365 TENSILE, MPa 28.9 22.0 24.9 23.9 22.5 23.2 TENSILE CHANGE, t S 1 12 1 -6 5 ELONGATION, t 220 215 230 220 200 205 ELONG, CHANGE, ~ -14 -10 -2 -12 -23 -11 HARDNESS A, pt's 81 79 79 80 79 80 HARD CHANGE, pt'a 6 7 6 9 9 6 168 hours at 150C

TENSILE, psi 3905 2895 3155 3135 3290 2825 TENSILE, MPa 26.9 20.0 21.8 21.6 22.7 19.5 TENSILE CHANGE, t -2 -8 -3 .9 -6 -12 ELONGATION, t 205 195 185 200 195 165 ELONG, CHANGE t -20 -19 -21 -20 -25 -28 HARDNESS A, pt's 79 77 81 82 81 80 HARD CHANGE, pt's 4 5 8 11 11 6 504 hours at 150C

TENSILE, psi 3420 2705 3005 2980 3080 2875 TENSILE,' MPa 22.4 18.7 20.7 20.6 21.3 19.8 TENSILE CHANGE, k -19 -14 -7 -13 -12 -10 ELONGATION, ~ 120 120 120 120 130 110 ELONG, CHANGE t -53 -50 -49 -52 -50 -52 HARDNESS A, pt's 84 80 84 87 87 85 HARD CHANGE, pt's 9 8 11 16 17 11 1008 hours at 150C

TENSILE, psi 3420 2560 2775 2920 2720 2540 TENSILE, MFe 23.6 17.7 19.1 20.1 18.8 17.5 TENSILE CHANGE, ~ -14 -19 -14 -15 -22 -21 ELONGATION, ~ 75 55 55 65 60 SO

ELONG CHANGE, t -71 -77 -77 -74 -77 -78 HARDNESS A, pt's 91 90 87 92 92 87 HARD CHANGE, pt's 16 18 14 21 22 13 70 hours at 150C

TENSILE, psi 3540 2750 3130 3095 3415 2875 TENSILE, MPa 25.1 19.0 21.6 21.9 23.6 19.8 TENSILE CHANGE, t -9 -13 -3 -10 -2 -10 ELONGATION, t 220 200 215 220 230 205 ELONG, CHANGE, t -14 -17 -9 -12 -12 -11 HARDNESS A, pt's 69 64 67 67 67 64 HARD CHANGE, pt's -6 -8 -6 -4 -3 -10 VOLUME CHANGE, t 14 15 14 12 12 15 168 hours at 150C

TENSILE, psi 3640 2040 3165 2775 3265 2840 TENSILE, MPa 25.1 14.1 21.8 19.1 22.5 19.6 TENSILE CHANGB, t -9 -35 -2 -19 -6 -11 ELONGATION, t 250 160 215 195 215 205 ELONG CHANGE, t -2 -33 -9 -22 -17 -11 HARDNESS A, pt's 63 62 67 65 66 64 HARD CHANGE, pt's -12 -10 -6 -6 -4 -10 VOLUME CHANGE, t 1~

2 ~ 9465 Example 2 This example illustrates compositions comprising a variety of partially hydrogenated nitrile rubbers admixed with the same polyacrylate elastomer. The experimental and test procedures utilized were the same as those of Example 1. The polyacrylate contains about 55% by weight of structural units derived from ethyl acrylate and about 45% by weight of structural units derived from n-butyl acrylate. The nitrile rubbers are partially hydrogenated nitrile rubbers containing from about 17 to 50% by weight of acrylonitrile and having a degree of unsaturation in the range of about 91-99%. Those partially hydrogenated rubbers containing about 17-25% of acrylonitrile also contain units derived from a third monomer, such as an alkyl ester or a dialkyl ester of an unsaturated carboxylic acid. The components of the curable compositions, the times and temperatures of curing, processing properties during curing, and the properties of the cured product, including the results of tests on aged products, are summarized below:

p ppooopp a __ N ~ v1 M h NI ~ N ~ M N M N ~ ~ ep~1 O~ '~ ~ M .-~ N ~ V N 00 ~ ~ V 'Q ~ ~ ~ M
O O O p O O O ~ ~ N h < V h NI ~ N ~ M N M N ~ Nv O O r ~ M ,r N ~ V ~ 00 N ~ V < ~ ~ N M M
O O O O O O O "; N ~'! W M h NI ~pp N $ M N M N ~ V e0~t ... '~ ~ ~ '~ N t~~1 h N ~ ~ O P CO O ~D N V1 V1 h h PI V .-. fV 1~1 t~1 O O O O O O O ~' N ~' e~1 ~1 ~O
NI O N ,~ M N M N ~ ~ t0~1 O~ "~ ~ P1 .-. N ~ h M O ~ 0v O~ CT h N
fn < .r Nt h ~ n O O O O O O O O M ~ ~O ~ .., M
O n N M N O O ,.", eo O c~~1 ~ O
NI N ~ .h-.. ~ Nf .. eil ~ ~' ~ ~ ~ ~ a ~ ~ ~ h ~ ~ 1~1 O O O p p O O O t~1 ~ < ~p ,., yp NI ~ N $ M N M N ~ ,'~ e0'1 .~ 'y tNf M .' N N ~ ~ h ~ O H V O p~ h O 1~1 h .~ N h < h .~ H1 1 ~1 O O ~ O O O O O O N ~O
~D ?
NI ~ N $ M N M N ~ ,~ t0"f ..~ '~ M Hf .~ N ~ V1 ~ Ov ~ ~ V h ~ ~ ~ 1~1 M
O O. O O O O O ~ ~'! M ~ N t~1 h M Ov NI ~ N $ M "N M N ~ ~ t0~1 .., 'y N M ~ N ~ h ~ V' B O O Y1 ~ O N V
h N h V v1 .. N en en 0 0 0 0 0 0 0 ° ~ ,., 00 0, .. oo v v, M
000 N $ M N M N ~ V1 O ~ .r 'Q nj ..n N h $ f~
N ~ M M ~ ~ ~ ~ V h ~ ~ N M N
O O O O O O O O r rf ~ < N h va~1 N v1 V1 NIA N $~NMN~ V t0~t ..n'.'M~.rN ~h~GT~n hh ~~~t~lN
O O O O O O O ~ ~'1 ~ 1~ h N p~
NI ~ N $ M t~l M N ~ V e0y1 .~ " m M .' N O ~O ~ 00 ~ Ov h ~ t.1 O Ov O
V H .-. fV fV
O O O O O O O O r M M ~ N ~D 00 O O~
NI ~ N $ M N M N f? C t0~1 ... " ~ M ~' N M VI ~ Ov ~ r V h ~ N N M M
a0 n f V V
it Z
a a o o M
a ~ ~
d ~ ~ U
..C.~~»»ZSSCS2~ ~ a ~ U~ ~ YG~~ ~~~c~o~Zl~U:~a U
g a a .~o ~ a a a a ~ .o a a a v o 9 Z > Z ~ 5 Z ~ g g ~ o °
= > > ~ ~ a ~ ~ a .° a ~ o ~ ~ ~ .~ N Y~ ~ S ~ E. .5 'L ~ .5 'E V 5 yr ~, ' ~ V z N Z ~°~n ~ a ~ ac ~ oe cc oc r~ r~ a a x a ~ o ., w a a Z E "a .5 p a a a a a a y a a a a a o ,5 a ~° is g o E ~ oH,~oaaxac~i~~~ ~~zzo~~~o~~uu~°~i~
o'&'s~s~s-s~s~s~s~ys-s ~ ~~ ~ ~, o o»w~~~~~~ NN~~'r~s~ooG" ° °
c8 azzzzz'zzzzzz'zu~ am a. ~ ~d t 94b52 h ra o oohalN In InmoNN orlrnoulallcrl r1u11llcrlh wlnolnNm.~ In rlmrnN.-1 N N

MN; h aN ~m I w ro ro ~ ~

m 111 U1 1f1 U7 O N ri I(1 N N h h r~l 10 N
m N VI N

1l1 v0 01 f~1 m IO h If1 01 I sh h Ov N N
rl h N N m Ii N

~, m r1 N ro m N N ro rl m I ro N m I W I W r1 OI

h O

O 1I1 O 01 111 1'1 t1 111 U1 O O 01 O O ri .-1 h VI m r1 h I-1 o 10 rl N m 01 N 'I
h N m m '-I N

1'7 H rl rl ro O N h 1 ro t0 e-1 I ro NI rl I W wI I ,-1 W rl rl W

t0 01 tl1 tl1 I1 111 u1 t~1 O 1l1 O O O r1 h rl m N N rl II1 N

01 h O O h O ID h O m h VI m a1 N .-1 ra N e-i N

H O N N ro O N N ro f'1 01 I ro I rl 1 GI rl 1 W H W
N

N

If1 If1 T IJ1 rv1 O 1l1 tl1 r1 t0 O V~ 10 f1 rl f~l O N O h a P'1 01 O 01 Ov N ID ~O m m H Ov Q1 N rl ? m H N 01 rl H

N rl W H ml W N rl W

M

tI1 1f1 rl O N 1f1 Il1 O O O O Ifi Ip l0 rl f~l fy1 N 10 l0 N

t0 h u1 l0 VI o1 OW l1 r~1 m r-1 01 01 N rl N m H N m rl 111 I ri I m rl I I
ro ~ ~ N ,-1 W ~ W

ri O tl1 m t'1 O N 1t1 01 O rl O O 01 10 dl ri ~1 N 10 V' N

N 01 tW I1 VI rl rl t~f O VI N m m -1 .-I
m1 m rl N m rl N

W M I PI 1 ro !~) 01 I rl 41 1'1 I ro I ro I '-1 CL ri W rl rl W
N

N

W O 1I1 trf 1IW 1 1f1 m O ml rl III m f'1 1'X1 N
O O N N N N

N m O f'1 h 'i ri 01 10 rl ID VI h 01 N N
m rl N m rl N

I ro 01 mI I
ro ~ ~ ~ ~ IL
~

O m O 1l1 m m u1 O O ri O VI 111 m 1l1 VI N rl O 01 VI rl N 41 tlf m N1 10 01 01 N r1 N m rl W 111 01 r1 N

pI I rl I ~ I N
ro ro N
I W

W p .
, i m In ohalmN omlnoaIhNN ohwulomrl.-1 rlolmNHm N m rIrINmr1 a Mrlalm,-f-.a N

rv ~ I a ~ m o ~ W
~ w I ~ I- .
1 ~ ~
I

h O 111 01 h U1 H If1 10 O rl 10 m N 111 rl O N rl O rl N

4G r1 Q1 t'~1 r~ h Ifi OW f~l m 1f1 T ri rl 01 1~1 m rl -1 N
N

NI w r1 1 ro r1 m I ro rW c m ro rl W H W N rl I W

N

a, 111 O t0 rl III fv1 U1 O O If1 N 111 O ri 01 N If1 VI N O
N

N f~l O1 h ID If1 I V N 1'X1 01 f~1 m T N ri -1 m N m rl N

~1 I ,~ 1 ro M a ~ I ro w I ro ri W r-1 W H W

a x N c>r x N w x N
x ro 1~-~ v x m ~ o ~n a za ai . .~ a ,~' a ra - a o, xo ca a a ~o trlxap, Wo ~xww Wln C7xww ~wE.~a~rCrn ~~ ~o,E~zoa~ ~L ~wE~zoa~
x a o.a rev x.~ uo~ ~~ x ro o~
H N ~ ~ ~ri U N C; H ro H U) H H (Il ro v v v a1 N .G v ri ri w E. cn N ca ~.i w t-I cn ..~.-~.-~ ro ~ v um ~ N aaa~ ~w oa ~ s~ aaaa ~~ m N ~.1~'1-./ UI01 11 HHN [~z ~ HHH(7('J
H N N N (.' 4'.~'Oo ~ tpUffOxx o O UIt/llllzz ~ ~ G O O H H O ~~ o 0 0 ~ ~ o ~. ~ ~ ~ ~ °a °a 0 o m m a r1.1 ro ro m o .c c~ ~ ~,,~ a m c~
z .C E~ H H W W aC aC rl z E~ E~ H W W ~-1 z m F N N W W H
H H m H O
U' O ~D U' O
R' h ri R' r-1 If1 01 N 1f1 O ~O tD 1(1 O Ov I~ Vf O T I~ t(1 (~1 m V' V' r1 U1 ry1 r1 r1 r1 In rl r~l tl1 O N
0! N M

rl V 10 r-I l~ V' IO u1 1 tl1 N ~ I (1 N 10 1 r1 r1 sN m t1 tn VI 10 I ,-I N ,i N
N N

n ~ I I-1' l0 V I ei ~ I~ rl I (~ r) I
I I '1 I

~

o N m o r In r w In In omc In In In am In ul r-mn .r rl r1 In w m rI '-r 1n .-1 '-~ m W W m 111 f1 f~ m VI l~ rl VI I IW -1 N I l0 n-1 ~O
ri 1~1 t~1 r~l t'1 VI 1D i -1 N ' rl 0 V N Ul l~ Ill I I-1 l0 VI I 1 ~ I~ rI I ~ l~ rI I
1 I ' I ro ro N

NI ~ ~ ~

O rl ml IJ1 O ri N ul O f~1 10 1l1 O f1 l0 II1 m t0 O O V~ '-1 O O V m f~ M m Ol l~ Pp t~ N
UI N

01 f~1 U) m (y1 ~p m1 I rl M Ill I rl t'1 r1 ~ 1'1 r/ V f'f 10 I N tD I 01 ('1 N f1 N

ro m ID 1-1 I m '-1 ~ m -I I
m '~ I I-1 ro ro ro ' NI y y y ~
~

1f1 I~ 01 O ri tD O O m m O u1 If1 m m O 1l1 If1 m 01 O 01 I~ t~l t11 n-i m I~ r1 m N
t~ r1 N N Ul I~ N m 1 V' ~ m r1 t~ I 1l1 N 1p I r1 N IO
t1 N r1 N r1 N r1 N 10 I G7 I tq H T 10 I ri I~ II1 I ei N m rl i ro '-1 m rl 1 ro ' b I I ro NI ~, ~, '~ ~, ., O O V If1 tf1 N N 1I1 IJ1 OW l1 O O OW 11 1I1 V
1D rl N 01 N rl N OI VI U1 r~W m N 10 N
N N O N

N N N N II1 O t~l rl O N V OI I~ O N I!1 OI I~
N N W t1 1f1 N Ul Ul N W

ro Q1 10 I rl O l0 1 n-1 ~ 10 I f~l [\ I H 1 I I 1 M
ro ro NI ~ ~ ~
~

O ~D 10 1f1 U7 O N O 01 VI V m O N 1I1 V m 1l1 N
r1 l0 V -I l~ f~1 rl r1 ri ~O N V rl ID N
N N

1I1 W 10 I~ N 1l1 ri O II1 I~ N O1 II1 1~ tp N VI N t~1 N V' N r~l W
N O!

~ ~ I ~ 1 m ~0 I r/ m ~ 1 m I
I n I ro ro NI a ~ ~ ~
~

o P1 m II1 O rl 1l1 o O 01 lD If1 1I1 O1 l0 Il1 f1 tl1 t~ ri t0 10 ar o N 10 VI (1 N ~D O!
O 0 o fll N

v-1 P1 10 ov rl UI V e-1 N t~l r~ r-1 O f1 l~
i ? N t~l N V N f1 t~ I N I W
N N

W 01 10 I r/ m lp I f-) W/ 1~ I rl M ~ I W I ro 1 I ro I I ro I ro NI ~I ~, ''1 t(1 01 O 1I1 Il1 to V O u1 OI rl O u1 aW 1 u1 V1 a0 O O O u1 r1 01 V1 u1 VI I~ O u1 ~D N
W O N N

O P'1 m I U1 f'~1 O\ m I-1 f~ Ii l0 rl tl1 rl V fn f1 N I VI N fv1 10 I W P I 01 N

ro Q1~O 1 / ~m W 1 ~m 1 -) I
~ I ~ I ro ro N
O

NI ~ y y ~
' -//

1l1 I~ m 111 O rl V II1 1IW '1 r1 O O t1 ri UI O m N VI m t~ N M 01 t~ O l~ 111 1D t0 ~O Ul l~ N N N OI r1 N N V I m tI1 O 1 O Ill l~
tl1 rl N U1 rl N U1 t~ N 01 N

01 l0 I 11 m 1D I r1 ~ 01 I ~ ~ yro n I I ~ ro ro NI y ~

O V N 1I1 tl1 O t0 111 O 01 Ill O 1l1 O1 tf1 O V
l~ 01 10 i rl V l~ V V rl U1 U7 ri 1f1 N
I~ N N M

t~ N f~l I~ t1 r-I VI r1 N f~ t~l 01 N I~ I
I yl N N N tl1 N N I N (71 0! U1 u o r I .-1 m ~a I .~ ~r al rl ~ r, o, I ro I ro I I ro ro I r1 W W r1 W e-I W
N

1l1 ll1 V~ U1 01 N II1 1l1 Ill N !!1 V1 U1 N O O r1 O f'1 VI \O N I~ N O 01 m 111 m If1 W
f'1 h N 01 VI N N N u1 n1 rl N I u1 tD r1 I f~ m I O1 It1 N N tp N Iff N N t 01 N

N m If1 I r/ ~ m rl ~ m ~ ~ I ~ I I I ro I ro NI ~ ~ ~

O m I1 O U1 1!1 O 01 o u1 m r1 111 o m ri O Uf O
O N N W vi t1 01 tI1 0f NI m 10 01 N N I~ ro m 1'1 m 1 t~ M t~ r1 M N m U1 1D f"1 N II1 I!1 VI PI f~1 VI N I~1 I W I~ I N
01 Ql 01 10 I rl m 1p I e~ ~ [~ I I ~ l~ I I-/ I
I I I ro ro ro NI ~ ~ ~

N
ll y W y ~ k N k N
X W ~ k H a .1~ m W x x m ~ x a x m a x o W - a p, O U W a p, O o , W ai C~ U w - a.l G1 o °a.ra a ca o °~.w w w ao °.rw w ra ao c~xw n. w r1 0 ..I ro C9 - C7 r1 In ..~ ro t7 ~ C9 H o ~.~ ro C9 . t7 H In ~.i ro C7 -oll,mw w oHUla oll,ma w o.-Imw w ~., w~~x~.~~a°~~ ~L w~ o a ~ o.~ wE~o~.tc~~~ o~ a~~o~a°~~
y! H In 10 ~ H U1 Vl V~ a - H UI ~j ? ro H N
N W W W H~' Il7 W W W H~' ul tn 3 ro W W W H~' u1 3 W W W H N
NHNN~f~J~ W ~ ~ HNHH~[~"j., w~ ~-' NHNN~U"'~,', w W i HHHH~(~~ W~
w~nm~nxx ~a~ a~n~n~nzx ~a~ H~n~n~nzz ~a~ ~~n~n~nxx i~o~d~~°,.~a~°~om i~.c°~~~.°a°a°~~o ° i~oc~~i~°a°a~~om i~~°c~~~°aa~°~~m z.dHHHww ~.-I 2 HHHWw >.-r x~CHHHWW >.n x HHHwW >~1 H H m H H m p: O A', r1 ~ O R' r1 2~9~6~~
Example 3 This example illustrates the effect of varying the relative proportions of the polyacrylate elastomer and the partially hydrogenated nitrile rubber in the mixture being peroxide-cured.
Examples 3A and 3B are for comparative purposes and do not represent compositions within the scope of the present invention.
The experimental and testing procedures utilized were the same as those of Example 1. The components of the curable compositions, the times and temperatures of curing, processing properties during curing and the properties of the cured product, including the results of aging tests, are summarized below:

~19~b52 00000000 h rl O M O tf1 II1 O ~ tf1 M O
N
O
Il1 H tf1 . . . h If1 O M . . eh O . N
O
M m N h M
N
O

M N r1 IO
r~ M 01 V' ri V' M
IO N
h I

r1 rl M rl r1 O O
O
O
O
O
O
O
O

rl Q1 M ll7 M
O O M
tf1 O
1l1 N
O

,'I,' u1 N tl1 O M 1f1 O rl O
M m N h N
N
~

M 1I e-1 h V1 .~ V1 M
~O N
IO

'i fi M H
ri O h O
O
O
O
O
O
O

01 h M O U1 01 M O

O
M

U' V1 h V' ~ M V1 O IO
O

M h N
M
N
O

M rl ri ID
h O1 M 10 M ri V~ r1 l0 N
h rl rl N rl rl 00000000 h 010 olMONto.r o wo oMO

O V' . . . m O M . . y1 O . ~
M
N
N
N

M rl r1 IO
h T M IO
M ri V1 ri ID N
IO

'i rl N ri rl O

O N
O
O
O
O
O
O

O O m V

O

W ~M . . ,..~~~p y, OOOMNNNIO . . 1n . ( M ri r1 10 m !f1 M
N N r1 01 rl I

r1 N rl O

O M
O
O
O
O
O
O

Qt III 1l1 M U1 O
O O m tl1 O
1p m O
m (a ~ . . . N ep U1 M . . eh II1 . h O
M er N t0 N
N
t0 M ri ri IO
m If1 N
rl N H m t0 M N
ri l r1 N H

O

O m O
O
O
O
O
O

m w u1 M tn h tp o o m In M o ~
ul ov UI V'M V'Mh M

M r-1 rl 111 01 If1 r1 rl N rl m lD M N
rl 'i N r1 O
O
O
O
O
O
O
O

N h N O O V1 O h t11 h tl1 O
O
h (p V . . . N M
1l1 M . . N
1l1 . ri O
M h N ID
N
N
~

M O r-1 W

10 rl M h 1p N

ri r1 N rl O
O
O
O
O
O
O

Ino NoloNtn.r ohomm~ 01 O M . . . In M
O M . .
M . m N
N N
N 1f1 a M m O O N
O N rl rl l M

-/ N
rl U

M

H

O

H E U U

p, 0 0 U O O

01 . 01 o rl Op H

o U

1-1 a.1 A il o m v~ro o ro o W W ~

,. W 1 m ~ m ., -1-a ro a a E
a a ada a ,~ ~ OI S
x o v ~ O ~ O ~N ~
W P Y
~

H ~1 v ~ st H .
w ~ i x I
x W E
1 ~
.
Eoo ~x v -.~ xF H H ty W p, m v W v ~ ~ ~ ~ o W
O T! % O x o 'O a O
, . .i O U H .,~ VW I0 O

11 ri ~ -ei rl -1 L', ml H
fll N U .i C7 ~ E W ~lZ h ~ E t~ G 0. * * -.a ~ W
H

rlu ZH ~a U wEwEE WN~naa.t(r]oW
.i H E W . N ~VIfIIHH('' Hfn v ~ 4 t T
4*

dl v . H W , U~o.-~ cn . N , ~'v O
.~x.-,x _ ~. ~o Na, H ~ NHO
ro.~~oavXE w~ H1n Ea, ] ~ ~O w ~~w ?~ U ~ O ~
N z H .~ ~~~Hf.
.d N
C
O

--l O W
a O ~ u~~
H w~
v .1 H
m ~' ~

n ro ,zu~a a o 'w ~' 19465 ~!1 fn O (.~ V1 00 '~ ~ M O ~ O OWO Ov N
"M" ~ ~ ~ ~ ..~.~ .-M. p N per" ~ Ov ~ N N et fV N
0.
x oo N V' ~ ~ ~ °i ea ~ ~ N N ~ ~ 00 O~ ~ ~~r1 O ~ N i ~ N N
M
00 ,~ ~ ~ .-~ N N ~ ~ N pp N N ~ ~ fV M c'~p M ~ p, ~, ~ p, Pr C .-. ~", C vp oO ~ H M ~ O p et WO p H M ~ ~ ~ O ~ 1~ N H
O ; ~ Y ~ ~ ~ ~ ~ N ~ ' ~ ~ 00 N N ~ ~ tV M
... M O tr1 00 00 H ~ Y1 p ~ N a0 Own ~: N ~ ~ ~ ~ ~ H
p~ ' ~ ~ ~ n ~ ~ O~ N ~ ~ ~ ~ ~O n N n ~ ..Mr ~ f~1 00 ~ N V1 ~ (V ~ 'O p 00 ~ H l~ ~ M N ~ M M M
r., r ~ ~ ~ ~ 00 ' N ~ ~ 00 ~O ~ N
V ~ 41 O ~ ~ ~D n n ~ ~ e'~' V~.f ~ V~'1 O O ~ N I1 OM p M ~O M ~O
M OW O (V M 00 .~ ~ ~ I~ N i ~ ~ 00 Y1 N ~ M r1 M N i-1 ' ~ P4 LL
00 00 ~ M d' r N ~ ~ .r ,_~., ~ M ~ ~ H M ~ ~ O .~-v tMY1 t~~1 M N
OMO V'1 n N ~i ~ ~i y0 M i ~ I~ ~!1 ~i N n n O ~' N pip N ~ 00 ~ 1' "' v~'1 O' ~ oo .-N. H ~ N N ~ N N ~ va M r ~O N i n ~ O~ ~O ' M ~y «., z M
~' a B°. H ~ ~ H~ zU
V til W o W ~n o. W
~~°~ awz A .N w ~ ~ ~ a ~ ~ A .N w ~ p ~ a ~ x ~ N ._ a. ~ ~ ~ d z x > ~ a ~ V ., v~ ~ ~ ~ a ~ V E--~ U ~ ~ V ~1 > 'o n. ~ C~ H U ~ ~ V C7 z o Gt7 fa7 W d U ~ V ~ ~ ~ W Lil W ~ ~ V ~ W W ~ u7 u7 W Q z U ~ W
'~~zzzooz oo~zzzooZ ao~~zzzoo~~.~o ~, www..~a~~~~ www..~..a~~o~ wwwa.~
HE-.E-'ww -.a HE-'Hww >-.a HE-.c-'wwxx>-.

~' 194652 Example 4 This example, like the previous example, illustrates the effect, in a somewhat different formulation, of varying the proportions of the polyacrylate elastomer and the partially hydrogenated nitrile rubber in the mixture being peroxide-cured.
Examples 4A and 4B are.for comparative purposes and do not represent compositions within the scope of the present invention.
The experimental and test procedures utlized were the same as those of Example 1. The components of the curable composition, the times and temperatures of curing, processing conditions during curing and the properties of the cured product, including the results of testing of the aged products, are summarized below:

~19~65~
O O tl1 u1 u1 10 1t1 O O If1 h N u1 1f1 O
O

N 10 LII 10 10m fy1 O m O 1f1 1'X1 Ifi O

(7 O r1 h C V' mi h O h N ri O O O 01 rl N h N
1t1 m N N
O N r1 t~1 h I1 tp h rl m rl ~-1 h I I
~ m 01 n N I
I

H rl rl N rl O O u1 u1 a~ 111 O O VI O H N

O

Nd. . . . . ohlnmu111r rlNa~oo . .

O O rl h V' r~l fi N m N rl O tl1 O H O 'i N h N
O m N1 N
W N f~1 rl V~ h to m rl 01 ri ri h O I 1 tf H H N v I I

~-1 r1 rl t~1 N

O O u1 tl1 rl h O
O O u1 N1 N u1 u1 O
O

m ~ . . . . If1 01 V~111 . . 1l1 O N
O II1 V~
O

O O H O h V' .-1 1f1 w1 V~ 10 N ri O It1 m N ri rl h h N
O N r1 N
W f'1 N

V' m 10 rl O H H h V~ I 1 N 1I1 H h rl I
I I
I

ri H n-1 N
ri O O W l1 u1 V~ l0 O
O O U1 f'~1 N
tI O Ifl O

m V, . . . . Iff ,-1 1p1l1 . . ul 171 ,-1 IIW l1 r1 O
h O O rl h V' V' fi N h 10 N I-1 O 1f1 O ni H M N h N
O m N
L1 N rv1 N

V' m ID m ei O rl H m N I I
N tl1 ri N N I

I

ri v-i rl rl t'~f N

m O O O O 111 111 tl1 O O U1 m O m I~1 rl h N m . . . . . . In 1(1 O r~l tl1 h M h N V' O O
U) O O O U1 O ~-1 O m N ID 171 ~ ID i-1 If1 N H r~l r1 ~ h ~ r1 h N '-1 N N
ry1 t~1 ~~ 01 ,~ Ifl rl 41 rl ra e-i rl N m l0 1f1 N I I I I t ri rl H P1 N
O O O O tI1 IJ1 1I1 O O U1 If1 01 O rl M O
If1 V~ O n-i O 1l1 N h N V~ O T
[I~~ O 111 O 1I1 O e1 O m N N I(1 ~ h ri m r1 rl r~1 h m ~ lD h N r~i N N f~'1 N
h m rW W -I ri O h h 1D N I I I I I
rl rl rl ~-W 1 rh N
O O O UI O 1I1 If1 O O 1f1 m 10 O m 1'X1 1f1 m rl ~ ~ ~ ~ ~ ~ O r~1 O N 111 M mi m (y1 ID N ~i A,'I O O 111 O U1 rl O m N N W N VW -1 V1 N .-1 N 10 ~ V~ 10 h N rl N N r~1 r'1 O W h n-1 ~-1 rl r1 O h 01 h N I 1 1 1 t H rl rl n-1 t~1 N
O
H

"' z a o o xH
a n - U pG
w O
0 o H
o a Ao ro o In H W H Cl ~ri N D
" w wu1 °o ~' r~ ~ ~~ x w~ w v ~ w HN m~ w~.~ - ...~ ro Exw w 'O 'O O W~~m ~ m~ OExxmol ftW
v .~ .~ v p; E H v H x ~ ~ rx o o a f z m o ~ v ,n x Xb x ro w o -zu F H a a.~, aooo o - hH o v o o -.~ N o ~.~ a s~ H o . ~.~ a E N ~ ~ H ~n z a ro U dl ~.~ E C9 tp o E ~ w ~ ~.i A W W F Vl O of 3 a rorl E ro NuH ~.a x H~ w a .a Ew E E - wwmv~aa~~HxO H
-~ ,L7 ~ ~r1 v G1 H > O E W U .-1 a ,q a o N E m v1 H H m O La U c>, ~.~UU~~b.~ ~n xU He x~x ~~, HH ~nv~~x ~Wn~, uo ~.'ii ro O vC~S~a~ C1 X~~ W dHll1 r,.~,.~ N.. H ~f0.7~~~e a o -N

~.~~ 0 N Nau7.-rol'i ~ u.~ ~ ~ ~9H OrI~~~~HH cnVIHHW~~''''~~LLPO -oW
N Ill n1 'i xwu~~nwr~>ww w fa ~ro U C9HHHH~

c194652 O h O 1f1 ~0 O~ 10 O O O~ O m N
m rl O m ~0 m r-1 h m N -1 CD rl 10 r1 N m a ao o, ,-r I ro M to I ~ I I
ro N 'i W N H PI

1f1 V~ 01 Il1 N m Il1 N V' U1 U1 W m -1 N O m fa, O I h N h 01 V' N m rl ~D
r1 N m .r m m ,.i I ro M vo ~ .1 I
~ ro N .~ a N rl a ovoMON.wom moNmaoaoho,m w ao M o~ .-m m o ~ M M vo I I m H N

M N Lw LL N rl u~MMwo,riwm ~woonwnOmm q h o I ao m ao I .-r mo ~ ~ m ar M M N ro Of O N I ro M N W N N (~

1I1 10 M O tf1 r1 tn M N U1 V' V' m d0 01 h m W o I o eI w m N rl N I vo ~ .~ m ~n~ N I ro NN I N ro M N On M N W

tl1 O h O N O If1 m If1 O W tll O 1D Q1 h m W In ~ M rl W m h ~ t M rl 1D I e-1 m sh O CD N I ro V' V~ N I ro V~ N LL M N W N
If1 V) tI1 O 01 O h m 1I1 M N If1 01 1(1 ED M m fi,' M ~ V~ 1 f7D m CO ~ N e-I r~1 10 I rl m V~ rl m N ro O rl I N I ro V~ N Gn M N W
a H
M
O
O~
V

r~
a~ x m x m ro x m. x m. x . a EEz..
~.a ro~ CW7 °~a ~o -.~ ro~x~ ~aCW7 o~.°~ w~~o~a~~ a~ wE~o~a~~
wwwLH-ncNry~ ~ ro wwwNU~~
aaart wVCa aaa~e ~W wcn H H H ~J (,h ,'Y., m H H H (7 (h ,7., ~~~i°a°a m ~o ~'v~~noo ao ~~~aaa~~om HcY. HE-INWW 1-1 H~~ HE~NWW >~
lo2a a°

Our invention has been described in terms of specific embodiments and non-limiting examples. Various modifications in the compositions of the present invention will be apparent to those skilled in the art and are included within the scope of the invention.

Claims (12)

1. A peroxide-cured blend comprising:
to 90 parts by weight of a polyacrylate elastomer comprising at least 10 mole % of the structural unit wherein R1 is a C4-8 alkyl group;
0 mole % to 30 mole % of the structural unit wherein R2 is an alkoxyalkyl group containing 2-12 carbon atoms;
and the balance to a total of 100 mole % of the structural unit wherein R3 is a C1-3 alkyl group; and 90-10 parts by weight of a partially hydrogenated nitrile rubber having a degree of unsaturation of from 0.1 to 20%.

2. A peroxide-cured blend according to claim 1, comprising to 30 mole % of the structural unit

3. A peroxide-cured blend according to claim 1, wherein R1 is n-butyl, R2 is methoxyethyl and R3 is ethyl.

4. A peroxide-cured blend comprising:
to 90 parts by weight of a polyacrylate elastomer comprising at least 10 mole % of the structural unit wherein R1 is a C4-8 alkyl group;
0 mole % to 30 mole % of the structural unit wherein R2 is an alkoxyalkyl group containing 2-12 carbon atoms;
1 to 10 mole % of the structural unit and the balance to a total of 100 mole % of the structural unit wherein R3 is a C1-3 alkyl group; and 10 to 90 parts by weight of a hydrogenated nitrile rubber having a degree of unsaturation of 1 to 20%.

5. A peroxide-cured blend according to claim 4, comprising 20 to 30 mole % of the structural unit

6. A peroxide-cured blend according to claim 4, wherein R1 is n-butyl, R2 is methoxyethyl and R3 is ethyl.

7. A peroxide-curable composition comprising a blend of:
to 90 parts by weight of a polyacrylate elastomer comprising at least l0 mole % of the structural unit wherein R1 is a C4-8 alkyl group;
0 mole % to 30 mole % of the structural unit wherein R2 is an alkoxyalkyl group containing 2-12 carbon atoms;
and the balance to a total of 100 mole % of the structural unit wherein R3 is a C1-3 alkyl group;

90 to 10 parts by weight of a hydrogenated nitrite rubber having a degree of unsaturation of from 0.1 to 20%; and a peroxide curing system.

8. A peroxide-curable composition according to claim 7 wherein the peroxide curing system comprises di-1,1-bis (t-butylperoxy)-3,3,4-trimethylcyclohexane and m-phenylenediamine bis-maleimide.

9. A peroxide-curable composition according to claim 7, comprising 20 to 30 mole % of the structural unit

10. A peroxide-curable composition which comprises a blend of:
to 90 parts by weight of a polyacrylate elastomer comprising at least 10 mole % of the structural unit wherein R1 is a C4-8 alkyl group;
0 mole % to 30 mole % of the structural unit wherein R2 is an alkoxylalkyl group containing 2-12 carbon atoms;
1 to 10 mole % of the structural unit and the balance to a total of 100 mole % of the structural unit wherein R3 is a C1-3 alkyl group;
90 to 10 parts by weight of a hydrogenated nitrile rubber having a degree of unsaturation of from 0.1 to 20%; and a peroxide curing system.

11. A peroxide-curable composition according to claim 10, wherein the peroxide curing system comprises an organic peroxide and m-phenyenediamine bis-maleimide.

12. A peroxide-curable composition according to claim 10, comprising 20 to 30 mole % of the structural unit