Note: Descriptions are shown in the official language in which they were submitted.
CA 02350719 2001-05-07
W O 00/27915 PCT/N L99/00683
Title: Rubber composition
The invention is in the field of recycling used
vulcanised, natural and synthetic rubber, more in particular
in the field of recycling vulcanised, ground tire rubber,
profiles, production waste and post consumer waste, to
produce polymer blends having useful properties.
In the recycling of used car tires, the re-use of the
rubber part of the tires has always posed substantial
problems. As the tire rubber scrap is vulcanised, regular
processing methods, like those used for recycling
l0 thermoplastic polymers, cannot be used. The rubber scrap is
substantially inert. Incineration and landfill are still the
major methods for disposal of old tires and recycling is
limited.
In a review article on the re-use of ground rubber
tire scrap (GRT) in Scheirs, J.; Polymer Recycling-Science,
Technology and Applications; John Wiley & Sons; Chichester,
1998; pag. 411-457, it has been indicated that filler
applications are still the main use of GRT. Re-use in virgin
material is still possible only to extends below about 10
wt.%, as the GRT acts as filler only.
In the past some experiments have been done with re-
use of vulcanised, ground rubber scrap from tires, by
blending them with polyolefins, using compatibility
enhancers, such as functionalized olefin polymers. In US
patent specification 5,157,082 various compatibility
enhancers have been disclosed. However, this method has only
limited use because of the expense of the specific additives.
Further, the properties of the final material are still not
sufficient to gain wide market acceptance.
Accordingly, there is a need in the art for systems,
wherein vulcanised, ground rubber scrap can be used in such a
way that useful rubber compositions are obtained; more in
particular in useful blends with the same material as the
CA 02350719 2001-05-07
WO OOI279I5 PCT/NL99/00683
2
origin of the rubber. Further, there is a need for the use of
this rubber scrap in said compositions, which compositions
may have a wide variety of physical and mechanical properties
such as useful hardness, values, ozone resistance, and the
ability to process the material on conventional rubber
processing equipment. More in particular there is a need for
re-use of ground rubber scrap in applications, wherein the
scrap replaces virgin rubber, while maintaining the
properties of the original virgin rubber. In this respect the
to term 'virgin rubber' is intended to indicate rubber that has
not yet undergone a vulcanisation or other crosslinking
treatment. The term 'rubber' is used in the conventional
sense of a polymeric substance having a glass transition
temperature well below -35°C, as defined in ASTM D3418.
The present invention is accordingly directed to a
rubber composition comprising
- an amount of 5 to 70 parts by weight of vulcanised,
ground rubber scrap,
- an amount of 1 to 30 parts by weight of a combination
of at least one EPDM rubber and at least one EVA copolymer,
the EPDM rubber and the EVA copolymer having undergone a
partial condensation reaction with an ethylene copolymer
having short chain branching
- an amount of 20 to 95 parts by weight of virgin
rubber .
Surprisingly, it has been found that such a rubber
composition, comprising on the one hand ground rubber scrap
and on the other hand the reaction product of EPDM and EVA
provides a superior quality rubber composition having
properties that may range from thermoplastic rubbers to
vulcanisable rubbers.
According to a first embodiment such a rubber
composition comprises 10 - 40 parts by weight of vulcanised,
ground rubber scrap, 15 - 45 wt.~ of the condensation product
of EPDM rubber and EVA copolymer and 20 to 75 parts by weight
of virgin rubber. According to another embodiment the rubber
CA 02350719 2001-05-07
WO 00/27915 PCT/NL99_/00683
3
composition comprises additionally an amount of from 1 to 20
parts by weight of oil, preferably a paraffinic oil.
When preparing the rubber composition according to
the invention it is preferred to react EPDM, EVA, ethylene
copolymer and (optional) other components together to give
the reaction product, which is then blended with the rubber
scrap, the virgin rubber and optional further components.
It is to be noted that the method of making a
reaction product from EPDM, EVA and other polymers have been
to described in various patent publications, such as US patent
numbers 4,877,827, 5,001,195, 4,997,880 and 5,017,659. In the
invention the product prepared according to these patents may
be used, or products having minor modifications thereof. The
contents of the said US patent specifications are
incorporated herein by way of reference.
In the composition of the present invention at least
one EPDM rubber should be present. This rubber is based on
ethylene, propylene and at least one diene monomer, such as
those conventionally used. Examples are dicyclopentadiene,
hexadiene, ethylidene-norbornene and the like. It is
preferred to use an EPDM that has a Mooney viscosity ML(1+4)
at 125°C between 8 and 60.
With respect to the EVA component, the copolymer of
ethylene and vinylacetate, it is to be noted that the same
comments apply. According to a preferred embodiment at least
one ethylene vinylacetate copolymer having a vinylacetate
content of between 25 and 40 wt.% is used. In accordance with
another preferred embodiment a combination of at least 2 EVA
copolymers is being used, one having a vinylacetate content
between 25 and 40 wt.%, whereas the other one has a
vinylacetate content between 10 and 20 wt.%. The relative
amounts of the two products are preferably between 1 . 2 to
2 :1.
As has been indicated previously the invention
requires that part of the EPDM and part of the EVA have
undergone a chemical reaction. In the preparation, the
CA 02350719 2001-05-07
WO 00/27915 4 PGT/NL99/00683
reaction conditions disclosed in the cited US patents can be
used.
According to the invention the condensation product
has undergone a reaction with an ethylene polymer having
short'chain branching. This polymer is suitably a linear low
density polyethylene, based on ethylene and at least one C4
to Cg copolymer. The amount of the copolymer ranges between 5
and 40 wt.~s calculated on the weight of EPDM, EVA and the
copolymer together.
In the present invention it is possible to use
vulcanised, ground rubber scrap, such as ground tire rubber
(GTR), which forms the largest amount of the rubber to be
recycled. However, it is also possible to use other
vulcanised natural or synthetic rubbers in the present
invention such as vulcanised SBR, vulcanised blends of
natural rubber and SBR, and vulcanised EPDM, BAN, butyl,
chlorobutyl or chloroprene rubber. Before use in the present
invention the vulcanised rubber is comminuted, preferably
grinded, preferably under cryogenic conditions until a
particle size preferably between 0.05 and 1.0 mm, preferably
between 0.05 and 0.5 mm has been obtained. It is to be noted
that GTR usually does not contain substantial amounts of
fibres or steel from the tires.
It is to be noted that the amounts of the
condensation product and the grinded rubber scrap are
related. Preferably the amount of scrap is at most 5 time the
amount of the condensation product, taking into account the
particle size of the scrap, finer particles requiring higher
amounts of condensation product.
Further a preferred component of the polymer
composition according to the invention is an oil component,
such as a paraffinic oil. This oil is preferably a regular
paraffinic oil that is used for extending rubbers.
The product of the invention further contains an
amount of virgin rubber, preferably of the same or comparable
type as the scrap. Virgin rubbers suitable are both natural
CA 02350719 2001-05-07
WO 00/Z7915 PCT/NL99/00683
and synthetic rubbers, or blends of two or more types of
rubber. As synthetic rubbers one may use nitril rubber, SBR,
EPDM rubber, butadiene rubber, butyl rubber, chlorinates
polyethylene (CPE), neoprene rubber, polyisoprene, and the
5 like.
The composition can be processed into conventional
rubber compositions, having the same properties as those
based on virgin rubbers, using the same or comparable recipes
as those valid for virgin materials. In this respect it is to
be noted that the recipes can be used as such, just replacing
the virgin material by the combination of the scrap and the
condensation product. The amounts of rubber that may be
replaced vary in dependence of the type of final product. For
thermoplastic rubber compositions this may be up to 70 wt.%
of the total composition, whereas for vulcanisable materials
this may be up to 40 wt.%.
Depending on the required properties the recipe may
be changed, such as the type of vulcanisation (or not),
amount of oil, fillers and the like.
The rubber composition according to the invention can
be used as such, as a thermoplastic elastomer. By careful
selection of the rubber, which is usually applied in an
amount of 20 to 40 wt.% based on the final blend, it is
possible to prepare a whole range of products from
(re)vulcanisable rubbers to thermoplastic elastomers having a
very high hardness value of up to 50 Shore D. Those products
may be used in the conventional manner just as the regular
virgin products would be used. This means that the rubbers
may for example be filled with carbon and other conventional
components. It is also possible to vulcanise the rubber
composition of the invention.
The invention is now elucidated on the basis of the
following examples.
CA 02350719 2001-05-07
WO 00/27915 6 PCT/NL99/00683
Example
A blend was prepared from 50 wt.% grinded tire scrap,
based on a vulcanised blend of NBR and SBR, 10 wt.% oil (OBI
10) and 40 wt.% of the reaction product of 47.5 wt.% of an
EVA copolymer having 28 wt.% vinylacetate, 47.5 wt.% EPDM and
5 wt.% of LLDPE, as described in Example 5 of US patent
specification No. 4,877,827.
This blend was mixed in a Banbury mixer at a
temperature of 180°C and granulated. The resulting material
was tested and the results were as follows:
Hardness (ISO 7619) 57
Hardness (168h at 70C) 51
Tensile strength (ISO 37) 2.9 MPa
Tensile strength (168h at 70C) 3.0 MPa
Elongation at break (ISO 37) 400%
Elongation at break(168h at 70C) 360%
Ozone resistance (ISO 1431-1)
480 h, 200 pphm, 40c, 50% elong. no effect
Liquid resistance (ISO 1817) 0% [v/v]
Example 2
Various compounds were prepared, based on EPDM rubber scrap
and virgin EPDM, with various.additives as enumerated in
Table 1. The amounts given in table 1 are based in wt.%. The
results of various tests, showing the importance of adding
the reaction product to obtain good properties, have been
included in the tables 2-4.
CA 02350719 2001-05-07
WO 00/27915 ~ PCT/NL99/00683
N
~
C
'O
C
N
t,:.
~O
N
v~ ~ O ~ ~ N d
~ ~
E
0
,ao ~ aN e~ r~ ss o 0
~n .- M 00 i
o ~ N
N ~ ~ -M dp .r ~ - '
a- N M
e-
E
> > ~, w
~ ~ ~M ~ ~ ~
M ~ ~
~ ~ <t N ~ O
U
~j U c
c
0
V L
E
c
o ~ o
U V
.
'E 'vi E O
N
O ~ t~
O O M "..'
o a o c
0
N > M
W a E ~n a
J ~ o c ~'-
00 0 ~ ~ L
Q a o a ca
c'o o
E E E fl c
L
L
,. V~ C
y, o
a a a
c c
o o
R
L
H V U7 U N tn U
V
3 7 .C
0 = ~ p p - ~2
CY a
1 ~ 4
p a ,
Q o p a a o o
o ~
~
c v c ~ a > a c
' a 1 'o
'
n o W ~ o_ v~
c_ o o_ c u
uJ c u
C 'D C 'O ~ C ~ O
U '~ ~ O 7 ~
~ ~
N W N cC
'>c~~a N '>c
>o~aV~
CA 02350719 2001-05-07
WO 00/27915 8 PCT/NL99/00683
~ r~ ao ~- ~ ao ° ~ o ~ o ~ ,- o co r~
~ t0 t0 .* N N + r- N N ~ j oo ~ N e~1 C~
00 O) N G1 ~ N ~ O O M m ~ ~ O>
t CO (~ + ~- N <'~7 ~. ~, ~ ~ ~' r. M tf1
'O
C
D. l~ d' Of M N M N ~°O M ~ N ~ N l0 f~-
1~ IO ~ ~ ~ + M M ' M N C~ 1~ Of r.
O
U
Q Q Q
0 0 o a a aaa
v c=n c'~n ~ g o ~~~ . ~ oe o
c c c
s s
U U U
V o 0
0
0 r'~ E
0 m ~
o
L L Q
U U c"w ~ L '
o
L ~
L
c o
O O t n
~
r.,_ N
N ~ ~
M
c c o)
J t t G~
C)
aoao c U
c
Q o ~ ~ U U U U
~
- r- ca ~ ~ o
co L
O y - M O O O
C C N N M 1'~~
~
~'
M
L L.
~ c ~ N C
O 0
c0N N
N
.C ~ ~ .~ L t ~ Z
t L
O
c0c0 ~ ~ ~ N N N N N
~
~G ~C~C
N N ~ : " .:.:.~:
.
~ ~ ~ N N N N tA
C
O y p7 ~ m
~ \ 'J ~
\
\
0
0
0
C C O ~ ~ c
G O p O O O O O
O
O N C C C C ~N ~N~t/f~i/fVi
M
~ ~ O O O N O C N V7tnN tn
~ U 'J
N /7 ~ tn ~ N ~ ~ N ~
N tn
NO O N ~ O O C W C ~ ~ O
~ O c '
D. O.G.d a.
O O
O O O O ~ y 'pO O O
O
O
i 1 ~ , U U U U U
O
IZ Z E....~ ~ W t t I- Q
~ ~ t 1
~
CA 02350719 2001-05-07
WO 00/27915 9 PCT/NL99/00683
~ a, N M 'a: ao r- ~; N ~"~ r.
_ ~ cc + ~ ~ .a~ co ~a ~ ~t
c
O tb f~ a0 ~ ~ ~ N '~ c0 a0 c'~
~G ~O + ~ C~7 00 r M e' '
O
U
Q Q Q
E
r s r a aaa ~ o
a~
v~
c
s
U
U U
0 0
0 0
M
J
00~
Q t f 0
0 0
H ~ ~ C
p)p7 C
C C
m N r
n
n
O N t0
~ ._.. ~ d
'
w. ,~ o o .C a
.. ~ w
w
c o C _
o
cp .
' C
p ~
tnN Vl CV f ~ N
~7 '
t~
VftAtn N U7 N _ 07
N
G C ~ ~ ~ O
C r
-o c ~ ~
E
~~ ~ C
'
z z z t ~ w r
-
CA 02350719 2001-05-07
WO 00/27915 10 PC'f/NL99/00683
~ c~ v, ao ~- ~o °- ~ o o r~
(O ~ O N O r + r- M sf ~ ~ ~ r ~ ~ ~ m
r r
'~~oON~' N Mrs rNr Oa00~p 000 ~j u'i
= t0 I~ . f ~ Oi a i , c~i P. C~ M N , ~ M N t- r
C
O l~ M N O 0D ap 1n 00 st' t~ O M r ~ P- n; 1n
N ~ M M O r' T O
E ~ 1~ I~ t ~ ~ ~ t M ~0 0 M F7 , ~ M N N T
O
U
Q Q Q
a~ a~ N ~ W ca co co ~ ~'
,ctr o ~yo Z~ E ~o\°o o\°
cn tn v~ ~ g a° ~ ~ ~ ~ E
a~
c
ca
U
U U
U U
0 0
~ h
o
O c~0~
r' L 4
V
O O
!~ C C
_
L L L
=
J L = ~ fafC
C _ _
pp
Q o ~ ~ ~ ~ U U U
o U
'
r r O ~ ~ 0 0 0
r 0
c c ~ asw ~-r oo
~ N N i~
I~
_ _ t s _
O O ~ _ _ _ _ lC
p L L N N ~C
L Q~~ L L L
L
0
L (~Cp N O N
ca~o
O .~CY ~C N P-N
N
'd ~ N d N .:.~.~:
..-%
t ~ ~ o L3 ~ ~ N ~ f0/7
t N
L L - 0 0
C C \ \
\
d ~ 000 p N N ~ 0 0 0
~ 0
_
O ~ J ~ O O O m _
L O
r N
M
N ,~, p O N U tnV)
N C
,
>
o~ d > > m m m N ~ a a n
~ ~ o
~ _ .
~
o ~ ~ ~ -w c c c ~ , E E E
~ ~ ~ E
~
0 c~ 0 0 0 0 0 0 0 0 0 0
0 ~ 0
0 o ~ ~ u u uJ h ~ U U U
~ Q U
Z Z I ~ h h J J
2
