Note: Descriptions are shown in the official language in which they were submitted.
~ 200303~ ::
TITLE
ALUMINUM $ILICATE-FILLED POLYOLEFIN COMPOSITIONS - -
The present invention relates to filled
thermoplastic polymer compositions and especially to
filled polyolefin compositions adapted to be
fabricated into articles having stiffness and
toughness properties that are superior to those ~ -
obtained with articles of the un-filled polyolefin; as
used herein, toughness refers in particular to impact
strength and ultimate tensile strength properties.
The filler is a modified aluminum silicate. As used
herein, aluminum silicate includes both~synthetic
aluminum silicates and naturally occurring aluminum
silicates e.g. clay and kaolin.
Polyolefins are used in a wide variety of end
uses, including in the form of film, fibres, moulded
or thermoformed articles, pipe and/or coatings. In
some end-uses, especially when the polyolefin is
fabricated into articles by moulding, extrusion or
thermoforming techniques, it is important that the
fabricated article exhibit stiffness and toughness -
properties that are superior to those obtainable from
- the polyolefin per se. Techniques for modification of ~;
the properties of polyolefins are known, including
cross-linking the polymer or incorporating additives -
or fillers into the polymer. Articles formed from
filled thermoplastic polymer compositions tend to
exhibit a higher stiffness than articles m~nufactured ` ;~
30 from thè corresponding uh-filled polymer, but such an i
increase in stiffness with filled compositions is
usually accompanied by a decrease in other important `
properties, including toughness.
Filled thermopolastic polymer compositions
containing a so-called "reinforcement promoter" are
known, and are discussed in published European patent
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application No. 257 796 of M.G. Dokurno, D.A.
Harbourne, and E. M. Lundhild, published 1988 ; ;
March 02. In addition, that publication discloses a
composition comprising 30-90 parts by weight of a
polyolefin, 10-70 parts by weight of a modified
polyethylene and 20-70% by weight based on the amount
of polymer of at least one filler selected from
magnesium hydroxide, calcium hydroxide, alumina
trihydrate, hydroxyl-containing carbonates of
magnesium and hydroxyl-containing carbonates of
calcium. The modified polyethylene is formed by
grafting at least one ethylenically unsaturated
carboxylic acid o~ anhydride thereof onto a
polyethylene. Other filled compositions are discussed
in that patent publication.
U.S. Patent 4 711 673 of L.L. Musselman et
al, issued 1987 December 08, discloses a filler
composition containing at least two surface modifiers -
and comprising a powdered inorganic filler, a
carboxylic acid or mixture of carboxylic acids and an
organosilane. Preferred organosilanes are stated to - ;
be vinyl-tris(2-methoxyethoxy) silane, organosilane
esters and methyl vinyl siloxane fluid. The filler
composition may be blended with thermoplastic
25 poly~ers. -
Japanese 57 172 940 of F. Iwami et al,
published 1982 October 25, discloses compositions that - ~
are obtained by admixing an inorganic filler that has - ~ -
been pre-coated with an organosilane compound, a ,
30 polyolefin ~polyprowlene), an unsaturated carboxyIic -
acid and an organic peroxide, in the presence of a ; ,
dispersing agent and an antioxidant. The resultant
compositions are stated to have excellent mechanical
strength and heat resistance, the examples ~ ~ `
illustrating compositions having Izod impact strengths
of 6.5 kg.cm/cm (63.8 Joules/m).
It has now been found that compositions of
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- - 3 - -
imp~oved impact strength may be obtained using -~
compositions of polyolefin, modified polyethylene and
amino silane-treated aluminum silicate.
Accordingly, the present invention provides a
composition comprising:
(a) 0-80% by weight of the composition of a
polyolefin selected from the group consisting of
homopolymers of ethylene and copolymers of ethylene
with at least one C3-C10 alpha-olefin, and
mixtures thereof;
(b) 10-70% by weight of the composition of a modified
polyethylene, said polyethylene being selected from
the group consisting of homopolymers of ethylene and
copolymers of ethylene with at least one C4-C10
alpha-olefin, and mixtures thereof, said polyethylene
having been modified by grafting at least one of an
ethylenically unsaturated carboxylic acid and an
ethylenically unsaturated carboxylic acid anhydride
onto said polyethylene, such that the resultant -
2Q modified polyethylene contains a total amount of -~
between 0.05 and 5.0% by weight, based on the weight
of polyethylene, of said acid and said anhydride; and
(c) 10-70% by weight of the composition of aluminum
silicate, said aluminum silicate having been surface
treated with an amino-silane compound.
In a preferred embodiment of the composition
of the present invention, the ethylenically
unsaturated carboxylic acid is maleic acid and the ; -~ -
ethylenically unsaturated carboxylic acid anhydride is
30 maleic anhydride. ' ; ~ ~ ;
The present invention also provides a process
for the manufacture of a polyolefin composition,
comprising~
(i) feeding to apparatus adapted for the admixing of
molten thermoplastic polymers with other materials, an
admixture of: (a) 0-80% by weight of the composition
of a polyolefin selected from the group consisting of
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homopolymers of ethylene and copolymers of ethylene :
with at least one C3-C10 alpha-olefin, and
mixtures thereof; (b) 10-70% by weight of the
composition of a modified polyethylene, said
polyethylene being selected from the group consisting
of homopolymers of ethylene and copolymers of ethylene
with at least one C4-C10 alpha-olefin, and
mixtures thereof, said polyethylene having been
modified by grafting at least one of an ethylenically
unsaturated carboxylic acid and an ethylenically
unsaturated carboxylic acid anhydride onto said
polyethylene, such that the resultant modified
polyethylene contains a total amount of between 0.05 ~ ~ .
and 5.0% by weight, based on the weight of
15 polyethylene, of said acid and said anhydride; and (c) .
10-70% by weight of the composition of aluminum - .
silicate, said aluminum silicate having been surface
treated with an amino-silane compound;
(ii) admixing (a), (b), and (c) at a temperature
above the melting point of the polyners of (a) and
(b), said temperature being below the temperature of
decomposition of both said filler and the polymers of :~
-, ., .. , ,:
(a) and (b); and .
(iii) extruding from the apparatus a composition
25 formed from (a), (b) and (c). ~: .:.
The present invention also provides a process
for the manufacture of articles comprising the steps
of feeding a composition to extrusion or moulding
apparatus, and forming said article by extruding or
moulding said composition into a shapéd article and
cooling the article so formed, said composition
,:. .: . ..- ~
comprising~
(a) 0-80% by weight of the composition of a :~
polyolefin selected from the group consisting of
homopolymers of ethylene and copolymers of ethylene `~
with at least one C3-C10 alpha-olefin, and -:
mixtures thereof;
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(b) 10-70% by weight of the composition of a modified
polyethylene, said polyethylene being selected from
the group consisting of homopolymers of ethylene and
co-polymers of ethylene with at least one C4-C10
alpha-olefin, and mixtures thereof, said polyethylene
having been modified by grafting at least one of an
ethylenically unsaturated carboxylic acid and an
ethylenically unsaturated carboxylic acid anhydride
onto said polyethylene, such that the resultant
lo modified polyethylene contains a total amount of
between 0.05 and 5.0% by weight, based on the weight
of polyethylene, of said acid and said anhydride; and
(c) 10-7Q% by weight of the composition of aluminum ~
silicate, said aluminum silicate having been surface ~ -
treated with an amino-silane compound.
The present invention also provides articles
manufactured using the processes described herein. ;
In embodiments of the compositions, processes :; ;
and articles of the present invention, a portion of
the aluminum silicate is replaced with a second
filler.
In another embodiment of the compositions,
processes and articles of the present invention, a -~
portion of the polymeric component is replaced with a
polar polymer.
The polyolefin of the composition of the
present invention is comprised of 0-80% by weight of
homopolymers of ethylene and/or copolymers of ethylene - ;~
with at least one C3-C10 hydrocarbon
alpha-olefin.l Examples of such alpha?olefins are
propylene, butene-l, hexene-l and octene-l. The
density of the polyolefin will normally be in the
range of about 0.895 to 0.965 g/cm3, especially in
the range of 0.920-0.960 g/cm3. The melt index of
35 the polyolefin is preferably in the range of 0.5-20 -
dg/min, especially in the range of 0.5-15 dg/min.
The density and melt index of the polyolefin
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used to form the compositions of the invention may be
varied over a wide range and will depend, in
particular, on the intended end-use of the articles
formed e.g. by injection moulding techniques, from the
compositions. Higher densities will tend to give
relatively stiff articles whereas lower densities will
tend to give more flexible articles.
The compositions of the invention also
contain a modified polyethylene. The polyethylene of
the modified polyethylene is a homopolymer of ethylene
and/or a copolymer of ethylene and at least one -
C4-c10 hydrocarbon alpha-olefin. Examples of such ;-
alpha-olefins are butene-l, hexene-l, and octene-l. ~ -
The polyethylene is modified by grafting the ;
15 polyethylene with at least one of an ethylenically -~
unsaturated carboxylic acid and an ethylenically
unsaturated carboxylic acid anhydride. Preferably the
acid is maleic acid and the anhydride is maleic
anhydride. The polyethylene that is modified by
20 grafting should have a density of at least 0.910, ;
preferably 0.920 g/cm3 and in particular at least -;
~ , , ~, .. .
0.950 g/cm', especially as the filled compositions
formed using such modified polyethylene tend to
exhibit flexural modulus properties that are superior
to the unfilled polymer.
Techniques for the preparation of grafted
copolymers are known in the art, preferred examples of
which are disclosed in published European Patent
Application No. 0 172 650 of G. White, published 1986 -~ -
February 26,ila~d i~ b.s. Patent 4 612 155 of C.S.! Wong
and R.A. Zelonka, which issued 1986 September 16.
Grafted copolymers may also be prepared by the thermal ~-
reaction of maleic anhydride with polyethylene or
elastomers at temperatures of at least about 375-C. ~ `
The modified polyethylene should have between
0.05 and 5.0%, by weight, of monomer grafted onto the
backbone thereof, and especially between 0.2 and 2.0%
. ~:
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200303~7
of grafted monomer. Both the amount of grafted
monomer on the polyethylene and the amount of the
grafted polyethylene in the composition will affect
the flow properties of the compositions of the
invention. For instance, higher amounts of ~rafted
monomer will result in higher interactions between the
grafted monomer and the filler, and consequently a
decrease in the flowability of the compositions. This
may be advantageous for some processes e.g. extrusion
and blow moulding processes, and disadvantageous for
other processes e.g. injection moulding processes.
Amounts of grafted monomer below 0.2 and especially
below 0.05~ by weight may not provide sufficient
improvements in the toughness of the resultant
15 products. ~-
The compositions of the invention contain
0-80% by weight of the composition of polyolefin and
10-70% by weight of the composition of modified
polyethylene, and especially 30 to 60% by weight of
polyolefin and 20 to 50% by weight of the modified
polyethylene.
The compositions of the invention also
contain 10-70% by weight of the composition of
aluminum silicate filler that has been treated with an
amino silane compound so as to modify the surface of
the filler. Examples of such fillers are available as
Translin~* 445 and 555 from Engelhard Corporation of
Edison, NJ, U.S.A. Translink fillers are described in
literature from the manufacturer as surface modified ~-
calcined aluminium;sllicates, the surface modification
providing hydrophobicity and dispersion properties.
Translink 445 grade is stated to be designed to be -
compatible with polyamides, polyesters and other polar
polymers, and to reduce water absorption, increase
tensile and flexural strength, increase the heat
deformation temperature and increase temperature
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stability. Translink 555 grade is stated to be
similar but with a finer particle size to increase
impact strength and flexural modulus.
In embodiments of the invention, the aluminum
silicate filler is prepared by calcining
air-classified or water-classified ground kaolin, in
order to dehydrate the kaolin, and then treating the -
resultant product with the amino-silane compound. The -
amino silane may of the formula R-Si X3 where R is
an organofunctional group, especially an alkyl
radical, and X is a hydrolyzable group e.g chlorine, -~
methoxy, ethoxy or acetoxy, and at least one of X and
R contains an amino radical. An example of such a
compound is 3-aminopropyl trimethoxy silane viz.
H2NCH2CH2CH2Si(OCH3)3- The hydrolyzable
radical is believed to react with -OH groups on the
surface of the filler particle, and the amino radical
is believed to provide a site that will react with the
monomer grafted on the polyethylene. -~
In preferred embodiments, the compositions
contain between 20 and 50% by weight of the aluminum -~
silicate filler. The particle size of the filler may
be important. It is known in the art that fine
particle size fillers tend to provide products of
higher impact strength than larger particle size
fillers.
The compositions of the invention may be `
manufactured by feeding the components of the ; ~ -
composition to apparatus adapted for the admixing of ~ ~-
thermoplast~ic !compositions. In particular, such !
components may be fed to a twin-screw extruder, a
high-intensity fluxing mixer e.g. a Gelimat* mixer or
a Farrell* continuous mixer. All of such apparatus is ~ -~
adapted for intensive mixing or compounding of
compositions. The apparatus is operated at
temperatures above the melting point of the polymers
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g
of (a) and (b) viz polyolefin and modified
polyethylene, and above the melting point of polar
polymers, if present.
After ad~ixing the compositions, the
compositions may be fed directly to apparatus for the
manufacture of articles, especially injection moulding ~ -
apparatus or apparatus for the extrusion of sheet or -
other profiles or blow moulding apparatus. However,
the compositions will usually be first formed into
comminuted shapes, for example, into pellets and other
comminuted shapes, and subsequently fed to apparatus
for the manufacture of articles.
The compositions may be subjected to a number -
of processes, especially injection moulding processes, -~ -
15 sheet-forming and blow-moulding processes. In ~ -
particular, the compositions may be injection mo~lded
or formed into articles that have a useful combination
of toughness and stiffness for many end-uses. For ; ~-
instance, the articles may be useful for sports and
20 recreation equipment, safety and personal protection `
eguipment, transportation and packaging equipment,
blow moulded containers and the like.
The present invention is illustrated by the
following examples:
Exam~le I
A number of compositions were made from
SCLAIR* 2907 polyethylene, which is an ethylene
homopolymer having a density of 0.960 g/cm3 and a
melt index of 5.0 dg/min.
0 ` The compositions were made using a twin-screw
compounding extruder from the polyethylene and one or ~
more of the following: ;
(a) MA-g-2909, an experimental grafted polymer formed ;
by melt grafting polyethylene with 0.62% by weight of ; ;~
maleic anhydride, the polyethylene being SCLAIR 2909
polyethylene, a homopolymer of ethylene having a
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density of 0.960 g/cm3 and a melt index of 13.5
dg/min;
(b) Zytel* 101 polyamide, a nylon 66
(polyhexamethylene adipamide polymer) available from
Du Pont Canada Inc.;
(c) Translink 555, an amino-silane surface treated
aluminum silicate having an average particle size of '
0.8 microns and a pH of 8.5-9.5: -
(d) Translink 445, an amino-silane surface treated -
aluminum silicate having an average particle size of
1.4 microns and a pH of 8.5-9.5; -
(e) Micropflex* 1200, a surface treated talc filler ;
available from Pfizer Minerals Division;
(f) Huber 70C calcined kaolin, an unmodified clay
with median particle size of 1.5 microns;
(g) Huber 80C calcined kaolin, an unmodified clay
with median particle size of 1.2 microns. -
Notched Izod impact strength was measured at -
23-C and at -40-C using the procedure of ASTM D-256.
The bars used were injection moulded at 200-C, except
for compositions containing the polyamide which were -
moulded into bars at 290-C. The bars had a thickness -~
of 0.32 cm. Flexural modulus was measured at 23-C ; ; ~ `
using the procedure of ASTM D-790. Tensile strength -
and elongation were measured using the procedure of
ASTM D-638, using Type IV dumbbells specified in that
procedure.
Further details and the results obtained are -~
given in Table 1.
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TABLE I
Grafted ~ :
Polymer Polyamide Filler
Run* Amount Amount Type Amount
No. (%) (%) (%~ ;~
; :
2 43.3
~: , ;,~ . . .' :. ~ '.
lo 3 - ~ c 30
: - ~," -.:
4 - - f 30
g 25
~ -
6 30 - c 30
'
7 26 - c 40 :;:~
8 30 - d 30
,.. . .
9 26 - d 40
c 30
11 25 20 c 30
,. . . ,~. .. ...
12 30 10 d 30
13 30 - c) 30) ;
e) 10) :
~:
~,. ..
Notei The amounts sho~ are on the basis of the final
~35 composition
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TABLE I (cont.
Notched Izod FlexuralTensileElongation
Run Impact Str. Modulus Strength at Break
No.(Joules/m) (GPa~ (MPa) (%~
23C -40JC
1 165 125 1.03 24.7 165 ; ~;
2 85 60 0.86 27.6 1200
10 3 50 45 1.54 29.0 315
4 35 NA 1.90 27.6 30 ~ -
~; '',. ' ,~''.:
NA 1.73 27.6 765
15 6 610 635 1.50 31.1 155
7 475 490 1.87 33.9 70
20 8 465 340 1.41 29.2 500
- :- -, :,
9 290 240 1.76 31.5 75
300 290 1.76 33.1 70
2 11 200 120 1.97 34.6 75
12 340 300 1.52 31.1 115
i3 ~ 300 275 ;' 1.6334.0 ~ 75 ~
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In Example I:
Run 1 is a comparative run using the polyethylene ::~
per se;
Run 2 is a comparative run using the polyethylene
and modified polyolefin, in the ratio that : - :
corresponds to Runs 7 and 9; ~-:
Run 3 is a comparative run of polyethylene and ~;
filler but without modified polyethylene, -~
which shows improvements in stiffness and
tensile strength over Run 1 but a decrease
in impact strength;
Run 4 is a comparative run of polyethylene and
untreated filler and shows similar r~sults
to Run 3;
Run 5 is a comparative run similar to Run 4 but
with a different untreated filler;
Runs 6-13 are runs of the present invention that show
major increases in the impact strength of ~ ;
the resultant products in comparison to
Runs 1-5. In addition both flexural
modulus and tensile strength show increases -~
over polyethylene;
Runs 10-12 are runs of compositions that contain
polyamide. The addition of polyamide
decreases impact strength but increases
tensile strength of the composition.
~ " '-:
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