U.S. patent application number 11/598906 was filed with the patent office on 2008-05-15 for process for crosslinking thermoplastic polymers with silanes employing peroxide blends, the resulting crosslinked thermoplastic polymer composition and articles made therefrom.
This patent application is currently assigned to General Electric Company. Invention is credited to Eric R. Pohl.
Application Number | 20080114134 11/598906 |
Document ID | / |
Family ID | 39370038 |
Filed Date | 2008-05-15 |
United States Patent
Application |
20080114134 |
Kind Code |
A1 |
Pohl; Eric R. |
May 15, 2008 |
Process for crosslinking thermoplastic polymers with silanes
employing peroxide blends, the resulting crosslinked thermoplastic
polymer composition and articles made therefrom
Abstract
In one embodiment herein there is provided a composition
comprising (i) one or more unsaturated silane compounds according
to the Formula (1): G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein
G.sup.1 is an olefinically unsaturated hydrocarbon group optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and (ii) a system of at least two peroxides comprising
a first peroxide having a first 0.1 hour half-life temperature and
a second peroxide having a second 0.1 hour half-life temperature,
the first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C. In another embodiment herein there is provided a
process for producing a silane-grafted thermoplastic polymer. In
yet a further embodiment herein there is provided a process for
producing a crosslinked thermoplastic polymer. In yet an even
further embodiment there is provided an article.
Inventors: |
Pohl; Eric R.; (Mount Kisco,
NY) |
Correspondence
Address: |
DILWORTH & BARRESE, LLP
333 EARLE OVINGTON BLVD., SUITE 702
UNIONDALE
NY
11553
US
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
39370038 |
Appl. No.: |
11/598906 |
Filed: |
November 14, 2006 |
Current U.S.
Class: |
525/474 ;
526/228 |
Current CPC
Class: |
C08K 5/5425 20130101;
C08K 5/14 20130101; C08K 2201/014 20130101 |
Class at
Publication: |
525/474 ;
526/228 |
International
Class: |
C08F 283/12 20060101
C08F283/12; C08F 4/38 20060101 C08F004/38 |
Claims
1. A composition comprising: (i) one or more unsaturated silane
compounds according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group, optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolysable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and (ii) a system of at least two peroxides comprising
a first peroxide having a first 0.1 hour half-life temperature and
a second peroxide having a second 0.1 hour half-life temperature,
the first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.
2. The composition of claim 1, wherein the unsaturated silane
compound is characterized in that G.sup.1 is vinyl or allyl,
R.sup.1 is a straight alkyl group having from one to six carbon
atoms, a branched alkyl having from 3 to 6 carbon atoms, an
unbranched cycloalkyl group of from 6 to 8 carbon atoms or a
branched cycloalkyl of from about 6 to 8 carbon atoms, and each of
X.sup.1 and X.sup.2 is independently an alkoxy group having one to
six carbon atoms.
3. The composition of claim 1, wherein the unsaturated silane
compound is selected from the group consisting of
vinylmethyldimethoxysilane vinylethyldimethoxysilane,
vinylmethyldiethoxysilane, vinylethyldiethoxysilane,
3-methacryloxypropylmethyldimethoxysilane,
N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations
thereof.
4. The composition of claim 1, wherein one or more of the
unsaturated silane compounds are according to the Formula (2):
G.sup.1R.sup.1SiZ (2) wherein G.sup.1 is an olefinically
unsaturated hydrocarbon group, optionally heteroatom-substituted
with one or more oxygen and/or nitrogen atoms; R.sup.1 is selected
from the group consisting of alkyl, aryl, aralkyl and arenyl; and Z
is a divalent hydrolyzable alkanedioxy group that forms a cyclic
structure with the silicon atom of Formula (2).
5. The composition of claim 4, wherein the unsaturated silane
compound of formula (2) is characterized in that G.sup.1 is vinyl
or allyl, R.sup.1 is a straight alkyl group having from one to six
carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an
unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a
branched cycloalkyl of from 6 to 8 carbon atoms and Z is a divalent
hydrolyzable alkanedioxy group having two to about 30 carbon
atoms.
6. The composition of claim 4, wherein the crosslinkable
unsaturated silane compound of Formula (2) is
2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane;
2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane,
2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and
combinations thereof.
7. The composition of claim 1, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 5.degree. C. to
about 110.degree. C.
8. The composition of claim 1, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 30.degree. C.
to about 90.degree. C.
9. The composition of claim 1, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 45.degree. C.
to about 70.degree. C.
10. The composition of claim 1, wherein the first peroxide is
selected from the group consisting of
bis-(2,4-dichlorobenzoyl)peroxide, tert-butylperoxypivalate,
dilauroyl peroxide, dibenzoyl peroxide,
tert-butylperoxy-2-ethylhexanoate,
1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane,
bis-(tert-butylperoxy)cyclohexane, tert-butyl
peroxy-3,5,5-trimethylhexanoate, tert-butylperoxyacetate,
tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide,
bis-(tert-butyl peroxyisopropyl)benzene,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and combinations
thereof; and the second peroxide is selected from the group
consisting of tert-butylperoxyacetate, tert-butylperoxybenzoate,
di-tert-amyl peroxide, dicumylperoxide,
bis(tert-butylperoxyisopropyl)benzene,
2,5-dimethyl-2,5-bis-(t-butylperoxy)hexane, tert-butylcumyl
peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne,
di-tert-butylperoxide and combinations thereof; wherein at least
one first peroxide is different from at least one second
peroxide.
11. The composition of claim 1, wherein the first peroxide is
selected from the group consisting of
bis-(2,4-dichlorobenzoyl)peroxide, dilauroyl peroxide, dibenzoyl
peroxide, 1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane,
tert-butylperoxybenzoate, dicumyl peroxide and combinations
thereof; and the second peroxide is selected from the group
consisting of tert-butylcumyl peroxide,
2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne and combinations
thereof; wherein at least one first peroxide is different from at
least one second peroxide.
12. A composition comprising: (i) one or more unsaturated silane
compounds according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group, optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the silane; (ii) a system of
at least two peroxides comprising a first peroxide having a first
0.1 hour half-life temperature and a second peroxide having a
second 0.1 hour half-life temperature, the first and second 0.1
hour half-life temperatures having a temperature differential in
said composition of at least about 5.degree. C.; and (iii) one or
more thermoplastic polymers; the composition optionally containing
one or more additional components capable of inhibiting silane
grafting and/or crosslinking during storage.
13. The composition of claim 12, wherein the thermoplastic polymer
comprises one or more polyolefins.
14. The composition of claim 13, wherein the one or more
polyolefins are polyethylene polymers or copolymers.
15. The composition of claim 13, wherein the one or more
polyolefins are selected from the group consisting of high-pressure
low-density polyethylene, medium- or low-pressure high-density
polyethylene, low-pressure low-density polyethylene, medium-density
polyethylene, ethylene-.alpha.-olefin copolymers, polypropylene,
ethylene-ethyl acrylate copolymers, ethylene-vinyl acetate
copolymers, ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers, ethylene-butene copolymers, polymethylpentene,
polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl
acetate terpolymers, and combinations thereof.
16. A composition comprising: (i) one or more unsaturated silane
compounds according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group, optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); (ii) a system of at least two peroxides comprising a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.; (iii) one or more thermoplastic polymers; and (iv)
one or more crosslinking catalysts; the composition optionally
containing one or more additional components capable of inhibiting
silane grafting and/or crosslinking during storage and/or
optionally at least one additive.
17. A silane-grafted thermoplastic polymer comprising a
thermoplastic polymer grafted to one or more unsaturated silane
compounds according to a process comprising subjecting a
composition comprising (i) one or more unsaturated silane
compounds, (ii) a system of at least two peroxides, and (iii) one
or more thermoplastic polymers, to conditions suitable for grafting
of the unsaturated silane compound to the thermoplastic polymer to
form a silane-grafted thermoplastic polymer, wherein: the one or
more unsaturated silane compounds are according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and the system of at least two peroxides comprises a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.
18. A process for producing a silane-grafted thermoplastic polymer,
the process comprising subjecting a composition comprising (i) one
or more unsaturated silane compounds, (ii) a system of at least two
peroxides, and (iii) one or more thermoplastic polymers, to
conditions suitable for grafting of the unsaturated silane compound
to the thermoplastic polymer to form a silane-grafted thermoplastic
polymer, wherein: the one or more unsaturated silane compounds are
according to the formula G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein
G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and the system of at least two peroxides comprising a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.
19. The process of claim 18, further comprising subjecting the
silane-grafted thermoplastic polymer to conditions suitable for
crosslinking of the silane-grafted thermoplastic polymer to produce
a crosslinked thermoplastic polymer.
20. The process of claim 18, wherein conditions suitable for
grafting of the unsaturated silane compound to the thermoplastic
polymer comprise subjecting the composition to a reaction
temperature between about a melting temperature and about a
degradation temperature of the thermoplastic polymer for a period
of time suitable for the at least partial grafting of the
unsaturated silane compound to the thermoplastic polymer.
21. The process of claim 20, wherein said reaction temperature is
in a range of about 140.degree. C. to about 260.degree. C. and said
period of time is about 0.5 to about 10 minutes.
22. The process of claim 19, wherein conditions suitable for
crosslinking of the silane-grafted thermoplastic polymer comprise
subjecting the silane-grafted thermoplastic polymer to moisture and
a crosslinking catalyst.
23. The process of claim 18, wherein the thermoplastic polymer
comprises one or more polyolefins.
24. The process of claim 23, wherein the one or more polyolefins
are polyethylene polymers or copolymers.
25. The process of claim 23, wherein the one or more polyolefins
are selected from the group consisting of high-pressure low-density
polyethylene, medium- or low-pressure high-density polyethylene,
low-pressure low-density polyethylene, medium-density polyethylene,
ethylene-a-olefin copolymers, polypropylene, ethylene-ethyl
acrylate copolymers, ethylene-vinyl acetate copolymers,
ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers, ethylene-butene copolymers, polymethylpentene,
polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl
acetate terpolymers, and combinations thereof.
26. The process of claim 18, wherein the unsaturated silane
compound is characterized in that G.sup.1 is vinyl or allyl,
R.sup.1 is a straight alkyl group having from one to six carbon
atoms, a branched alkyl having from 3 to 6 carbon atoms, an
unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a
branched cycloalkyl of from 6 to 8 carbon atoms and each of X.sup.1
and X.sup.2 is independently an alkoxy group having one to six
carbon atoms.
27. The process of claim 18, wherein the unsaturated silane
compound is selected from the group consisting of
vinylmethyldimethoxysilane vinylethyldimethoxysilane,
vinylmethyldiethoxysilane, vinylethyldiethoxysilane,
3-methacryloxypropylmethyldimethoxysilane,
N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations
thereof.
28. The process of claim 18, wherein one or more of the unsaturated
silane compounds are according to the Formula (2):
G.sup.1R.sup.1SiZ (2) wherein G.sup.1 is an olefinically
unsaturated hydrocarbon group, optionally heteroatom-substituted
with one or more oxygen and/or nitrogen atoms; R.sup.1 is selected
from the group consisting of alkyl, aryl, aralkyl and arenyl; and Z
is a divalent hydrolyzable alkanedioxy group that forms a cyclic
structure with the silicon atom of Formula (2).
29. The process of claim 28, wherein the unsaturated silane
compound of Formula (2) is characterized in that G.sup.1 is vinyl
or allyl, R.sup.1 is a straight alkyl group having from one to six
carbon atoms, a branched alkyl having from 3 to 6 carbon atoms, an
unbranched cycloalkyl group of from 6 to 8 carbon atoms, or a
branched cycloalkyl of from 6 to 8 carbon atoms and Z is an
alkanedioxy group having from 2 to about 12 carbon atoms.
30. The process of claim 28, wherein the unsaturated silane
compound of Formula (2) is
2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane;
2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane,
2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and
combinations thereof.
31. The process of claim 18, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 5.degree. C. to
about 110.degree. C.
32. The process of claim 18, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 30.degree. C.
to about 90.degree. C.
33. The process of claim 18, wherein the temperature differential
between the first and second 0.1 hour half-life temperatures of the
first and second peroxides is in the range of about 45.degree. C.
to about 70.degree. C.
34. The process of claim 18, wherein the first peroxide is selected
from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide,
tert-butylperoxypivalate, dilauroyl peroxide, dibenzoyl peroxide,
tert-butylperoxy-2-ethylhexanoate,
1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane,
bis-(tert-butylperoxy)cyclohexane, tert-butyl
peroxy-3,5,5-trimethylhexanoate, tert-butylperoxyacetate,
tert-butylperoxybenzoate, di-tert-amyl peroxide, dicumylperoxide,
bis-(tert-butyl peroxyisopropyl)benzene,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and combinations
thereof; and the second peroxide is selected from the group
consisting of tert-butylperoxyacetate, tert-butylperoxybenzoate,
di-tert-amyl peroxide, dicumylperoxide,
bis(tert-butylperoxyisopropyl)benzene,
2,5-dimethyl-2,5-bis-(t-butylperoxy)hexane, tert-butylcumyl
peroxide, 2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne,
di-tert-butylperoxide and combinations thereof; wherein at least
one first peroxide is different from at least one second
peroxide.
35. The process of claim 18, wherein the first peroxide is selected
from the group consisting of bis-(2,4-dichlorobenzoyl)peroxide,
dilauroyl peroxide, dibenzoyl peroxide,
1,1-bis-(tert-butylperoxy)-3,3,5-trimethylcyclohexane,
tert-butylperoxybenzoate, dicumyl peroxide and combinations
thereof; and the second peroxide is selected from the group
consisting of tert-butylcumyl peroxide,
2,5-dimethyl-2,5-bis-(t-butylperoxy)-3-hexyne and combinations
thereof; wherein at least one first peroxide is different from at
least one second peroxide.
36. A process for producing a crosslinked thermoplastic polymer,
the process comprising: a) subjecting a composition comprising (i)
one or more unsaturated silane compounds, (ii) a system of at least
two peroxides, and (iii) one or more thermoplastic polymers, to
conditions suitable for grafting of the unsaturated silane compound
to the thermoplastic polymer to form a silane-grafted thermoplastic
polymer; and b) subjecting the silane-grafted thermoplastic polymer
of step (a) to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer to form a crosslinked
thermoplastic polymer; wherein: the one or more unsaturated silane
compounds are according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group, optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and wherein the system of at least two peroxides
comprise a first peroxide having a first 0.1 hour half-life
temperature and a second peroxide having a second 0.1 hour
half-life temperature, the first and second 0.1 hour half-life
temperatures in said composition having a temperature differential
of at least about 5.degree. C.; the conditions for silane grafting
according to step (a) and for crosslinking according to step (b)
are the same or different, and wherein steps (a) and (b) are
conducted simultaneously or consecutively.
37. The process of claim 36, wherein the thermoplastic polymer
comprises one or more polyolefins.
38. The process of claim 37, wherein the one or more polyolefins
are selected from the group consisting of high-pressure low-density
polyethylene, medium- or low-pressure high-density polyethylene,
low-pressure low-density polyethylene, medium-density polyethylene,
ethylene-.alpha.-olefin copolymers, polypropylene, ethylene-ethyl
acrylate copolymers, ethylene-vinyl acetate copolymers,
ethylene-propylene copolymers, ethylene-propylene-diene
terpolymers, ethylene-butene copolymers, polymethylpentene,
polybutenes, chlorinated polyethylenes, chlorinated ethylene-vinyl
acetate terpolymers, and combinations thereof.
39. The process of claim 36, wherein the unsaturated silane
compound is selected from the group consisting of
vinylmethyldimethoxysilane vinylethyldimethoxysilane,
vinylmethyldiethoxysilane, vinylethyldiethoxysilane,
3-methacryloxypropylmethyldimethoxysilane,
N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations
thereof.
40. The process of claim 36, wherein the unsaturated silane
compound is 2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane;
2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane,
2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and
combinations thereof.
41. An article produced by a process comprising: a) providing a
composition comprising: (i) one or more unsaturated silane
compounds according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1) wherein G.sup.1 is an
olefinically unsaturated hydrocarbon group, optionally
heteroatom-substituted with one or more oxygen and/or nitrogen
atoms; R.sup.1 is selected from the group consisting of alkyl,
aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); (ii) a system of at least two peroxides comprising a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.; and (iii) one or more thermoplastic polymers; b)
subjecting the composition of step (a) to conditions suitable for
grafting of the unsaturated silane compound to the thermoplastic
polymer to form a silane-grafted thermoplastic polymer; c)
subjecting the silane-grafted thermoplastic polymer of step (b) to
conditions suitable for crosslinking of the silane-grafted
thermoplastic polymer to form a crosslinked thermoplastic polymer;
and, d) producing the article therefrom before, and/or during
and/or after conducting step (c), wherein the conditions for silane
grafting according to step (b) and for crosslinking according to
step (c) are the same or different, and wherein steps (b) and (c)
are conducted simultaneously or consecutively.
Description
BACKGROUND OF THE INVENTION
[0001] (1) Field of the Invention
[0002] This disclosure relates to a composition comprising a
silane, and a system of peroxides and a process of crosslinking
thermoplastic polymers with said composition. The disclosure
further relates to the moisture crosslinked thermoplastic polymers
resulting from the process and articles made therefrom.
[0003] (2) Description of Related Art
[0004] For many applications, e.g., wire and cable insulation,
weatherstripping, fibers, seals, gaskets, foams, footware, flexible
tubing, pipes, bellows, tapes, etc., certain selected properties
(e.g. tensile strength, compression set, thermal and chemical
resistance) of articles manufactured from one or more thermoplastic
polymers can be enhanced by introducing chemical linkages between
the polymeric molecular chains which constitute the polymer, during
or specifically following, the shaping or molding process. These
chemical linkages between different polymeric molecular chains are
commonly referred to as "crosslinks". Crosslinks can be introduced
between different molecular chains of a thermoplastic polymer by a
number of mechanisms, one of which is to graft to the individual
polymer backbones or chains that constitute the bulk polymer with a
chemically reactive compound in such a manner that the grafted
compound on one backbone may subsequently react with a similar
grafted compound on another backbone to form the crosslink.
Exemplary of this process is the "silane crosslinking" process.
[0005] The silane crosslinking process employs a silane-containing
thermoplastic polymer that crosslinks when exposed to moisture.
Silanes can be grafted onto a suitable thermoplastic polymer by the
use of a suitable quantity of free radical initiator, either before
or during a shaping or molding operation. Additional ingredients
such as stabilizers, pigments, fillers, catalysts, processing aids
etc., may also be included in the mixture.
[0006] When using practicing silane cross-linking for thermoplastic
polymer, a compromise must be made between grafting efficiency and
processing efficiency, such as extrusion rate and run times. The
formation of a crosslinkable material by this means is, however,
difficult to carry out since it requires critical control of the
process. If the free radical initiator, for example, reacts too
quickly with the thermoplastic polymer, then the thermoplastic
polymer may partially crosslink and solidify in the processing
apparatus, for example an extruder, with consequent difficulties in
achieving consistent and good quality products and in avoiding
delays involved in removing the partially crosslinked product from
the processing equipment.
[0007] It has been observed that gel formation, screw-build up and
scorching may result when using highly reactive silane
cross-linking blends. This gel formation is particularly
significant for processes using conditions and processing equipment
that impose severe melting and mixing conditions leading to high
shearing stresses in the thermoplastic polymer. These problems
generally arise due to early and eventually complete activation of
the free radical initiator during the initial melting and
homogenization process. The prior art has dealt with these problems
by using less reactive silane cross-linking blends but this
approach can diminish the grafting efficiency of the crosslinkable
thermoplastic polymers.
[0008] The silane compositions of the prior art can also generate
volatile organic compounds in amounts that are a potential fire or
explosion hazard and may be deleterious to the environment.
[0009] Thus, there remains a need for a means of crosslinking
polyolefins and other silane crosslinkable thermoplastic polymers
under reactive mechanical-working conditions using silane
crosslinkers and free radical initiators while minimizing such
aforenoted problems as gel formation, screw-buildup and/or
scorching, fire or explosion hazards while maintaining a high level
of grafting efficiency.
BRIEF SUMMARY OF THE INVENTION
[0010] In one embodiment herein, there is provided a composition
comprising silanes with an unsaturated organic functional group and
two hydrolyzable groups, and a system of at least two peroxides;
and there is also provided herein a process of crosslinking
thermoplastic polymers by reacting thermoplastic polymers with
novel compositions of these silanes and system of at least two
peroxides under reactive mechanical-working conditions.
[0011] In one embodiment herein, there is provided a composition
comprising:
[0012] (i) one or more unsaturated silane compounds according to
the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl, and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group, or alternatively each of
X.sup.1 and X.sup.2 is a hydrolyzable group having a direct bond to
the silicon atom and also simultaneously a direct bond to each
other to form a ring with the silicon atom of the unsaturated
silane of Formula (1); and
[0013] (ii) a system of at least two peroxides comprising a first
peroxide having a first 0.1 hour half-life temperature and a second
peroxide having a second 0.1 hour half-life temperature, the first
and second 0.1 hour half-life temperatures in said composition
having a temperature differential of at least about 5.degree.
C.
[0014] In another embodiment herein, there is provided a process
for producing a silane-grafted thermoplastic polymer, the process
comprising subjecting a composition comprising (i) one or more
unsaturated silane compounds, (ii) a system of at least two
peroxides, and (iii) one or more thermoplastic polymers, to
conditions suitable for grafting of the unsaturated silane compound
to the thermoplastic polymer to form a silane-grafted thermoplastic
polymer, wherein the one or more unsaturated silane compounds are
according to Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and the system of at least two peroxides comprising a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.
[0015] In yet another embodiment, herein there is provided an
article, produced by a process comprising:
[0016] a) providing a composition comprising: [0017] (i) one or
more unsaturated silane compounds according to the Formula (1):
[0017] G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group, or alternatively each of
X.sup.1 and X.sup.2 is a hydrolyzable group having a direct bond to
the silicon atom and also simultaneously a direct bond to each
other to form a ring with the silicon atom of the unsaturated
silane compound of Formula (1); [0018] (ii) a system of at least
two peroxides comprising a first peroxide having a first 0.1 hour
half-life temperature and a second peroxide having a second 0.1
hour half-life temperature, the first and second 0.1 hour half-life
temperatures in said composition having a temperature differential
of at least about 5.degree. C.; and [0019] (iii) one or more
thermoplastic polymers;
[0020] b) subjecting the composition of step (a) to conditions
suitable for grafting of the unsaturated silane compound to the
thermoplastic polymer to form a silane-grafted thermoplastic
polymer;
[0021] c) subjecting the silane-grafted thermoplastic polymer of
step (b) to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer to form a crosslinked
thermoplastic polymer; and,
[0022] d) producing the article therefrom before, and/or during
and/or after conducting step (c),
wherein the conditions for silane grafting according to step (b)
and for crosslinking according to step (c) are the same or
different, and wherein, optionally in one embodiment steps (b) and
(c) are conducted simultaneously or consecutively.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The expression "reactive mechanical-working conditions"
herein shall be understood to mean the conditions within a
mechanical working apparatus, such as an extruder, of elevated
temperature and sufficient residence time to bring about reactive
processing which include activating the herein described system of
at least two peroxides and graphing the herein described
unsaturated silane onto the herein described thermoplastic
polymer.
[0024] It will be understood that all ranges stated herein comprise
all subranges there between and can further comprise any
combination of ranges and/or subranges.
[0025] It will be understood that unless stated otherwise, all
percents are weight percents based on the total weight percent of
the herein described composition.
[0026] In one embodiment herein, the unsaturated silane compounds
according to the Formula (1) can comprise specifically at least one
compound of the Formula (1) and more specifically at least two
different compounds of the Formula (1). In one specific embodiment
herein, G.sup.1 represents an olefinically unsaturated hydrocarbon
group, that is optionally hetero-atom substituted with one or more
oxygen and/or nitrogen atoms. In one more specific embodiment,
G.sup.1 contains of from about 2 to about 20 carbon atoms, more
specifically of from about 2 to about 18 carbon atoms, even more
specifically of from about 2 to about 12 carbon atoms, yet even
more specifically of from about 2 to about 10 carbon atoms and most
specifically of from about 2 to about 6 carbon atoms. As used
herein, G.sup.1 is an unsaturated hydrocarbon group that contains
at least one carbon-carbon double bond. Herein, G.sup.1 can be
optionally substituted with one or more oxygen and/or nitrogen
atoms, more specifically at least one oxygen atom and at least one
nitrogen atom, and even more specifically two or more oxygen atoms
and/or two or more nitrogen atoms. The olefinically unsaturated
hydrocarbon group of G.sup.1 that is heteroatom substituted can
comprise where the heteroatom is part of an ester group
(--CO.sub.2--), ether group (--O--), ketone group (--C(.dbd.O)--),
amide group (--C(.dbd.O)N(--).sub.2) and/or an imide group
(--C(.dbd.O)N(--)C(.dbd.O)--) group. Some specific examples of
G.sup.1 include, but are not limited to alkenyl groups, such as the
non-limiting examples vinyl, allyl, butenyl, cyclohexenyl,
cyclopentenyl,and 2-[4-(2-propenyl)phenyl]ethyl; alpha,
beta-unsaturated carbonyl groups, such as the non-limiting examples
3-methacryloxypropyl, 1-methacryloxymethyl,
5-methacryloxy-3-oxapentyl, 6-methacryloxy-3-oxahexyl,
3-acryloxypropyl, 1-acryloxymethyl,
##STR00001##
and vinyl substituted aryl groups, such as the non-limiting
examples styryl and 4-vinylbenzyl.
[0027] In one embodiment herein, R.sup.1 is can be selected from
the non-limiting examples of alkyl, aryl, aralkyl, and arenyl. More
specifically, as used herein, "alkyl" includes straight, branched
and cyclic alkyl(cycloalkyl) groups, as well as cyclic alkyl groups
that are branched; "aryl" includes any aromatic hydrocarbon from
which one hydrogen atom has been removed; "aralkyl" includes, but
is not limited to, any of the aforementioned alkyl groups in which
one or more hydrogen atoms have been substituted by the same number
of like and/or different aryl (as defined herein) substituents; and
"arenyl" includes any of the aforementioned aryl groups in which
one or more hydrogen atoms have been substituted by the same number
of like and/or different alkyl (as defined herein) substituents.
When R.sup.1 herein is alkyl, R.sup.1 can contain of from 1 to
about 30 carbon atoms, more specifically of from 1 to about 20
carbon atoms, even more specifically of from 1 to about 12 carbon
atoms and most specifically of from 1 to about 6 carbon atoms,
provided that when R.sup.1 is a branched alkyl group R.sup.1
contains at least 3 carbon atoms. In another embodiment, R.sup.1 is
a cyclic alkyl group that contains at least 3 carbon atoms and
specifically wherein R.sup.1 is a branched cyclic alkyl group
R.sup.1 contains at least 4 carbon atoms. When R.sup.1 is
cycloalkyl (branched or unbranched) herein, R.sup.1 can contain
specifically of from 6 to about 8 carbon atoms. When R.sup.1 is
aryl herein, R.sup.1 can contain of from 6 to about 30 carbon
atoms, more specifically of from 6 to about 20 carbon atoms, even
more specifically of from 6 to about 12 carbon atoms and most
specifically of from 6 to about 8 carbon atoms. When R.sup.1 is
aralkyl or arenyl herein, R.sup.1 can contain of from 7 to about 30
carbon atoms, more specifically of from 7 to about 20 carbon atoms,
and most specifically of from 7 to about 12 carbon atoms. Some
specific non-limiting examples of R.sup.1, that are alkyls,
include, but are not limited to, methyl, ethyl, propyl, isopropyl,
butyl, hexyl, octyl, ethylcyclohexyl, norbornyl, cyclopentyl, and
cyclohexyl and most specifically methyl and ethyl. Some specific
non-limiting examples of R.sup.1 that are aryls include, but are
not limited to, phenyl and napthalenyl. In one other specific
embodiment some specific non-limiting examples of R.sup.1 that are
aralkyls include, but are not limited to, benzyl and phenethyl. In
yet a further embodiment some specific examples of R.sup.1 that are
arenyls include, but are not limited to, tolyl and xylyl. The
R.sup.1 group as described herein does not contain any
crosslinkable moiety in any embodiments herein, and R.sup.1 does
not contain any unsaturation that can be used in graphing as
described herein.
[0028] In a more specific embodiment herein, in Formula (1), each
X.sup.1 and X.sup.2 independently represents a hydrolyzable group,
wherein each of X.sup.1 and X.sup.2 has a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1). In one specific embodiment herein X.sup.1 and X.sup.2
are not bonded directly to each other and are hydrolyzable groups.
In another specific embodiment herein, X.sup.1 and X.sup.2 have a
direct bond to each other as described above.
[0029] X.sup.1 and X.sup.2 when not having a direct bond to each
other can each independently represent the same or different
hydrolyzable organic group such as an alkoxy group containing of
from 1 to about 30 carbon atoms, more specifically of from 1 to
about 20 carbon atoms, even more specifically of from 1 to about 12
carbon atoms and most specifically of from 1 to about 6 carbon
atoms, such as the non-limiting examples of methoxy, ethoxy,
propoxy, isopropoxy, butoxy, isobutoxy groups; acyloxy group
containing of from 1 to about 30 carbon atoms, such as the
non-limiting examples of formyloxy, acetoxy, propanoyloxy,
benzoyloxy and octanoyloxy groups; oximato groups containing of
from 1 to about 30 carbon atoms, such as
--ON.dbd.C(CH.sub.3).sub.2, --ON.dbd.C(CH.sub.3)CH.sub.2CH.sub.3,
--ON.dbd.C(CH.sub.3)CH.sub.2CH.sub.3 and
--ON.dbd.C(C.sub.6H.sub.5).sub.2 groups; or substituted amino
groups containing of from 1 to about 30 carbon atoms, such as
alkylamino and arylamino groups, some non-limiting examples of
which are --NHCH.sub.3, --NHC.sub.2H.sub.5 and
--NH(C.sub.6H.sub.5). X.sup.1 and X.sup.2 herein when not having a
direct bond to each other are each independently methoxy or
ethoxy.
[0030] In one embodiment herein of Formula (1), each X.sup.1 and
X.sup.2 have a direct bond to the silicon atom and a direct bond to
each other to form a ring with the silicon atom of the unsaturated
silane of Formula (1) by any chemical method and/or reaction that
will result in the formation of silicon-containing ring that
contains a bond of any element in X.sup.1 to any element in
X.sup.2. Such a ring can contain a group (such as the non-limiting
example of Z described herein) which is the result of any chemical
method and/or reaction that results in the direct bond of X.sup.1
and X.sup.2 to each other; so that thereby such a group can contain
the bonded reaction product of at least two of the groups
identified above for X.sup.1 and X.sup.2 when X.sup.1 and X.sup.2
do not have a direct bond to each other. In another embodiment
herein, X.sup.1 and X.sup.2 of Formula (1) have a direct bond to
silicon and to each other to form a silicon-containing ring by the
non-limiting example of the chemical method of removal of a
hydrogen atom that was previously directly bonded to a carbon atom
in X.sup.1 and X.sup.2, from each of X.sup.1 and X.sup.2
respectively and thus allowing the bonding of the two respective
carbon atoms in X.sup.1 and X.sup.2 that had hydrogen removed
therefrom. In yet a further embodiment, X.sup.1 and X.sup.2 of
Formula (1) have a direct bond to silicon and to each other to form
a silicon-containing ring by the non-limiting example of the
chemical method of removal of a hydrogen atom that was previously
directly bonded to an atom other than a carbon atom in X.sup.1 and
a hydrogen atom that was previously bonded to a carbon atom in
X.sup.2, from each of X.sup.1 and X.sup.2 respectively, and thus
allowing the bonding of the respective non-carbon atom and carbon
atom in X.sup.1 and X.sup.2 respectively that each had a hydrogen
atom removed therefrom.
[0031] In one specific embodiment, unsaturated silane compound of
the general Formula (1) when X.sup.1 and X.sup.2 have a direct bond
to each other as described above, can have the more specific
Formula (2):
G.sup.1R.sup.1SiZ (2)
wherein G.sup.1 and R.sup.1 are as defined above and wherein the Z
group is a divalent hydrolyzable group that forms a cyclic
structure with the silicon atom of formula (2). In one embodiment Z
of general formula (2) that forms a cyclic structure with the
silicon atom of formula (2) is a divalent hydrolyzable group of
specifically from 2 to about 30 carbon atoms, more specifically
from 2 to about 18 carbon atoms and most specifically from about 2
to about 12 carbon atoms. In another specific embodiment Z of
general formula (2) is a divalent hydrolyzable alkanedioxy group
that has the general Formula (3):
--O(R.sup.2CR.sup.2).sub.cO-- (3)
wherein each occurrence of R.sup.2 is hydrogen or R.sup.1 as
defined above and wherein c is an integer of from 2 to 6,
specifically 2 or 3. In one specific embodiment herein, when each
of X.sup.1 and X.sup.2 of Formula (1) have a bond to each other, as
described herein, they result in the formation of the above
described Z group. In one more specific embodiment of the Z group,
at least two R.sup.2 groups are not hydrogen. Some specific
examples of Z group include, but are not limited to,
2,3-butanedioxy, 2-methyl-1,2-propanedioxy, 2,3-hexanedioxy;
2,2-dimethyl-1,3-propanedioxy, 2-methyl-2,4-pentanedioxy,
2,3-dimethyl-2,3-butanedioxy, and
2,4-dimethyl-2,4-pentanedioxy.
[0032] In another embodiment, the unsaturated compounds of Formula
(2) are formed by the transesterification of unsaturated compounds
of Formula (1), wherein X.sup.1 and X.sup.2 are not interconnected
to each other, in which said transesterification results in X.sup.1
and X.sup.2 being replaced by a divalent hydrolyzable alkanedioxy
group, such as the non-limiting example of formula (3) and wherein
the two oxygen atoms of the structure in Formula (3) are bonded
directly to the silicon atom of the unsaturated silane of Formula
(2). In one embodiment Formula (2) can be formed by
transesterification of the silane of Formula (1), wherein X.sup.1
and X.sup.2 are not connected to each other, with an alkanediol and
optionally in the presence of a transesterfication catalyst, such
as para-toluenesulfonic acid, in which said transesterification
results in X.sup.1 and X.sup.2 being replaced by a divalent
hydrolyzable alkanedioxy group such as the non-limiting example of
formula (3) wherein the two oxygen atoms of the structure in
Formula (3) are bonded directly to the silicon atom of the
unsaturated silane of Formula (2). The term "alkanediol" as used
herein refers to an alkane in which two hydrogens have been
substituted with two hydroxyl groups and is also commonly referred
to as glycol or diol. The preparation of unsaturated silanes of
Formula (2) is disclosed in US Patent Application 2006/0036034A1,
which is incorporated herein by reference in its entirety.
[0033] The structure of Z is important in the formation of the
silicon-containing cyclic structure. R.sup.2 groups that are more
sterically hindered than hydrogen promote the formation of the ring
containing Z and the silicon atom. R.sup.2 groups that are more
sterically hindered than hydrogen can be the non-limiting examples
of specifically, alkyl groups of from 1 to about 18 carbon atoms,
more specifically of from 1 to about 3 carbon atoms and most
specifically methyl. R.sup.2 groups other than hydrogen that can be
used herein are alkyl groups, such as the non-limiting examples of
methyl, ethyl, n-propyl, isopropyl, butyl, octyl and dodecyl; aryl
groups such as the non-limiting examples of phenyl or napthalenyl;
aralkyl groups, such as the non-limiting examples of benzyl or
2-phenylethyl; and arenyl groups, such as the non-limiting examples
of tolyl and xylyl. The attachment of two R.sup.2 groups to a
single carbon atom results in a "gem dihydrocarbyl group". Gem
dihydrocarbyl group(s) further promote the formation of a ring
containing a silicon atom and Z, a divalent alkanedioxy group such
as the non-limiting group of Formula (3). Some non-limiting
examples of a gem dihydrocarbyl group are selected from the group
consisting of alkyl, aryl, aralkyl and arenyl groups described
herein. The formation of a ring structure containing a silicon atom
and the Z, alkanedioxy group such as the non-limiting example of
Formula (3) is also promoted when the values of c is 2 or 3 because
the size of the ring then becomes 5 or 6, which promotes a more
stable ring structure. It is undesirable when the two oxygens of
the Z group are attached to a different silicon atom in that it
would form a silane that has two silicon atoms that are connected
by the Z group and two unsaturated organic groups. During the
reactive mechanical-working conditions, these silanes containing
two unsaturated organic groups will crosslink the thermoplastic
polymer described herein within the mechanical-working apparatus
and cause scorch.
[0034] The unsaturated silane of Formula (1) can contain only two
hydrolyzable organic groups or in the instance where X.sup.1 and
X.sup.2 have a direct bond to silicon and a direct bond to each
other as described herein, one group in which a hydrogen atom of
each of X.sup.1 and X.sup.2 has been replaced by an oxa (--O--)
group and wherein each oxa group is bonded to the X.sup.1 and
X.sup.2 and to the silicon atom.
[0035] The unsaturated silane of Formula (1) as described above can
have one olefinically unsaturated group and two hydrolyzable groups
attached to the silicon atom or the instance where X.sup.1 and
X.sup.2 have a direct bond to silicon and a direct bond to each
other as described herein.
[0036] When these silanes described herein are graphed onto the
thermoplastic polymers described herein and crosslinked, the
polymer chains are connected to each other at crosslink points
containing three tie points. The thermoplastic crosslinked polymers
described herein will have higher elongations and are more flexible
than thermoplastic polymers crosslinked with molar equivalent
amounts of silanes outside of the scope of the disclosure herein,
which possess one unsaturated group and three hydrolyzable groups
or with two unsaturated groups and two hydrolyzable groups, wherein
said unsaturated group(s) and hydrolyzable groups are the same
group as is used in Formula (1) or (2). The crosslinked
thermoplastic polymers made using silanes of the general Formulae
(1) or (2) have an elongation of specifically from about 1 to about
100 percent, more specifically of from about 1 to about 50 percent,
and most specifically of from about 1 to about 20 percent higher
than thermoplastic polymers crosslinked with a molar equivalent
amount of silanes possessing one unsaturated group and three
hydrolyzable groups, or silanes possessing two unsaturated groups
and two hydrolyzable groups, wherein said unsaturated group(s) and
hydrolyzable groups are the same group as is used in Formula (1) or
(2). In one specific embodiment herein, the crosslinked
thermoplastic polymers made using silanes of the general Formula
(2) have a reduced level of volatile organic compound (VOC)
emission of specifically from about 30 to about 100 percent, more
specifically of from about 66 to about 100 percent, and most
specifically of from about 85 to about 100 percent lower than
thermoplastic polymers crosslinked with a molar equivalent amount
of silanes with one unsaturated group and three hydrolysable
groups, such as the low molecular weight alkoxy groups (e.g.
methoxy or ethoxy), that are commonly used; or silanes possessing
two unsaturated groups and two hydrolyzable groups, wherein said
unsaturated groups and hydrolyzable groups are the same group as is
used in Formula (1) wherein X.sup.1 and X.sup.2 are not bonded
directly to each other. The reduced levels of VOC's are due to the
high boiling points of the alkanediols that are generated after the
silane of Formula (2) reacts with moisture. These high boiling
alkanediols do not readily evaporate during processing and after
the polymer is crosslinked. In one embodiment herein, any
composition, process or article described herein has the same
levels of reduced VOC as described above. Elongation is determined
herein by the method described in ASTM D-638. In one specific
embodiment herein the crosslinked thermoplastic polymers made using
silanes of the general Formulae (1) and/or (2) are more flexible,
as determined by a lower modulus, and specifically have a modulus
from about 1 to about 200 percent, more specifically of from about
5 to about 50 percent, and most specifically of from about 10 to
about 25 percent lower modulus than polymers crosslinked with a
molar equivalent of silanes possessing one unsaturated group and
three hydrolyzable groups or silanes possessing two unsaturated
groups and two hydrolyzable groups, wherein said unsaturated
group(s) and hydrolyzable groups are the same group as is used in
Formula (1) or (2). Modulus is determined herein by the method
described in ASTM D-638. These later polymers, which are outside
the current disclosure, are crosslinked with silanes outside of the
scope of this disclosure which possess one unsaturated group and
three hydrolyzable groups or possess two unsaturated groups and two
hydrolyzable groups have crosslinks that have four tie points. In
addition, the silanes possessing two unsaturated groups and two
hydrolyzable groups, which are outside of this disclosure, can
undergo the graphing reactions with two different polymer chains.
The silane with two unsaturated groups and two hydrolyzable groups,
which are outside of this disclosure can therefore bond two polymer
chains together during graphing reactions and thus significantly
and undesirably increase the molecular weight of the polymer. The
resulting silane graphed polymers from silanes with two unsaturated
groups and two hydrolyzable groups, which are outside of this
disclosure, will have a significant decrease in melt flow index
which will make them more difficult to process and mold. In one
specific embodiment herein, the two hydrolysable groups X.sup.1 and
X.sup.2 of the silanes of Formula (1) are also more important if
X.sup.1 and X.sup.2 are connected such as is the case in one
non-limiting example of Formula 1 and also in Formula (2). In one
embodiment herein, the connected X.sup.1 and X.sup.2 group is
represented by Z. The Z groups herein can readily form cyclic
structures, especially if the Z group contain more sterically
hindered substituents other than hydrogen, such as R.sup.1, as is
described above. If the unsaturated silane herein contained three
hydrolyzable groups, which is outside the scope of the disclosure
herein, then two Z groups could react with a single silicon atom;
one of the Z groups would form a cyclic structure; the second Z
group could form a bridge between two different silicon atoms.
These bridged structures that contain two unsaturated groups are
capable of graphing reactions with two different polymer chains.
Bonding two different polymer chains together in the graphing
reactions increase the polymers molecular weight and decreases the
melt flow index, resulting in the problems of scorch such as is
discussed above.
[0037] In one specific embodiment herein, the unsaturated silane
compound of Formula (1) is characterized in that G.sup.1 is vinyl
or allyl, R.sup.1 is straight alkyl having from 1 to about 6 carbon
atoms, a branched alkyl having from 3 to 6 carbon atoms, or a
unbranched cycloalkyl group of from 6 to about 8 carbon atoms, or a
branched cycloalkyl of from 6 to 8 carbon atoms and each of X.sup.1
and X.sup.2 is independently an alkoxy group having from one to six
carbon atoms.
[0038] In one embodiment some non-limiting examples of silanes of
the general Formula (1) include vinylmethyldimethoxysilane,
vinylethyldimethoxysilane, vinylmethyldiethoxysilane,
vinylethyldiethoxysilane,
3-methacryloxypropylmethyldimethoxysilane,
N-(3-methyldimethoxysilylpropyl)methacrylamide and combinations
thereof.
[0039] In another specific embodiment herein the unsaturated silane
compound of Formula (2) is characterized in that G.sup.1 is vinyl
or allyl, R.sup.1 is a straight alkyl group having from 1 to about
6 carbon atoms, a branched alkyl having from 3 to 6 carbon atoms,
or an unbranched cycloalkyl group of from 6 to about 8 carbon atoms
or a branched cycloalkyl of from 6 to 8 carbon atoms and Z is a
alkanedioxy group having specifically from 2 to 12 carbon atoms,
more specifically from 2 to about 8 carbon atoms and most
specifically from 2 to about 6 carbon atoms.
[0040] In yet another specific embodiment herein the unsaturated
silane compound of Formula (2) is
2,4,4,6-tetramethyl-2-vinyl-[1,3,2]dioxasilinane;
2-methyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-vinyl-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-vinyl-[1,3,2]dioxasilinane,
2,4,4,6-tetramethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-methyl-5,5-diethyl-2-(3-methacryloxypropyl)-[1,3,2]dioxasilinane,
2-phethyl-5,5-diethyl-2-(1-methacryloxymethyl)-[1,3,2]dioxasilinane,
2-methyl-5-ethyl-2-(2-methacryloxyethyl)-[1,3,2]dioxasilinane and
combinations thereof.
[0041] In one embodiment herein the above described system of
peroxides comprises a first peroxide having a first 0.1 hour
half-life temperature and a second peroxide having a second 0.1
hour half-life temperature, the first and second 0.1 hour half-life
temperature having a temperature differential of specifically at
least about 5 degrees Celsius (.degree. C.), more specifically at
least about 15.degree. C. and most specifically at least about
30.degree. C.
[0042] The system of peroxides possesses a differential of 0.1 hour
half-life temperatures, as described herein, such that undesired
early and/or concentrated activation of the system of peroxides is
decreased; further, the differential of 0.1 hour half-life
temperature allows for a controlled level of activation and
grafting throughout the reactive processes described herein, which
leads to an improved level of grafting efficiency and silane
crosslinking efficiency in the grafted and/or crosslinked
thermoplastic polymers described herein. The use of peroxides
containing a range of 0.1 hour half-life temperatures, as described
herein, has been observed to reduce the level of gel formation,
screw buildup and/or scorching allowing for extended run-times.
[0043] In one embodiment herein, the amount of gel formation
obtained after crosslinking the silane-graphed thermoplastic
polymer compositions described herein is specifically of from about
10 to about 100 weight percent, more specifically of from about 50
to about 99 weight and most specifically of from about 75 to about
95 weight percent, said weight percents being based on the total
weight of the composition.
[0044] The system of peroxides comprises specifically at least two
peroxides, more specifically at least three peroxides and most
specifically at least four peroxides. In another embodiment herein,
the 0.1 hour half-life temperature of the second peroxide is
between 5.degree. C. and 110.degree. C. greater than the 0.1 hour
half-life temperature of the first peroxide. In yet another
embodiment, the 0.1 hour half-life temperature of the second
peroxide is between 30.degree. C. to 90.degree. C. greater than the
0.1 hour half-life temperature of the first peroxide. In still
another embodiment, the 0.1 hour half-life temperature of the
second peroxide is between 45.degree. C. and 70.degree. C. greater
than the 0.1 hour half-life temperature of the first peroxide.
[0045] In one embodiment, the first peroxide possesses a relatively
low 0.1 hour half-life temperature, of specifically from about
80.degree. C. to about 160.degree. C., more specifically of from
about 90.degree. C. to about 155.degree. C. and most specifically
of from about 100.degree. C. to about 135.degree. C. In one
embodiment, the specific peroxide 0.1 hour half life temperature(s)
indicated herein are calculated using the data and formulae
provided in the downloadable Arkema spreadsheet found at the
website address of www.arkema-inc.com/index.cfin?pag=353 by
downloading the link which is highlighted as "Download Half-Life
Selection Guide" on said webpage, and using the formula presented
in the "Classical Plot" page in said Half-Life Selection Guide, for
the cell identified as the 6 minutes (0.1 hour) half-life, which is
used with the data for Activation Energy (Ea (kcal/gmole)) and A
constant (A(1/sec)) being provided for individual peroxides on the
separate page in said Half Life Selection Guide entitled Data and
Configure. By utilizing the appropriate Activation Energy and A
constant data for a particular peroxide, in the formula, one
obtains a value for the 0.1 hour half-life temperature of the
peroxide in the respective solvent indicated in the spreadsheet
Data and Configure. The formula which was used for determining the
specifically provided 0.1 hour half-life temperature of the
peroxides herein is identified the "Classical Plot" page in said
Half-Life Selection Guide, for the cell identified as the 6 minutes
(0.1 hour) half-life and is: (Activation Energy/0.001987)/LN((A
Constant multiplied by 360)/0.693))-273.15. It will also be
understood herein that other conventionally known techniques for
determining 0.1 hour half-life of a particular peroxide can be used
to obtain a respective 0.1 hour half-life temperature of a
respective peroxide. LN is understood to be natural logarithm. Some
suitable first peroxides and their range of 0.1 hour half-life
temperatures are set forth in Table I as follows.
TABLE-US-00001 TABLE I First Peroxide First Peroxide 0.1 hour
half-life temperatures, .degree. C. Bis-(2,4-dichlorobenzoyl) 93
peroxide Dilauroyl peroxide 99 Dibenzoyl peroxide 113
1,1-Bis-(tert-butylperoxy)- 128 3,3,5-trimethylcyclohexane
Tert-butyl peroxybenzoate 142 Dicumyl peroxide 154
[0046] In another embodiment herein some additional first peroxides
can include tert-butyl peroxypivalate, tert-butyl
peroxy-2-ethylhexanoate, bis-(tert-butyl peroxy)cyclohexane,
tert-butyl peroxy-3,5,5-trimethylhexanoate, tert-butyl
peroxyacetate, di-tert-amyl peroxide, bis-(tert-butyl
peroxyisopropyl)benzene and 2,5-dimethyl-2,5-di-(tert-butyl
peroxy)hexane, as well as any peroxide that is conventionally used
or known. In one embodiment herein, first peroxide can comprise a
combination of any of the herein described first peroxides.
[0047] In one embodiment, the second peroxide possesses a higher
0.1 hour half-life temperature than that of the first peroxide,
specifically the 0.1 hour half-life temperatures of the second
peroxide are on the order of from about 125.degree. to about
190.degree. C., more specifically from about 140.degree. to about
170.degree. C. and most specifically of from about 155.degree. C.
to about 165.degree. C. In another embodiment some suitable second
peroxides and their range of 0.1 hour half-life temperatures are
set forth in Table II as follows.
TABLE-US-00002 TABLE II Second Peroxides Second Peroxide 0.1 hour
half-life temperatures, .degree. C. Tert-butyl peroxybenzoate 142
Dicumyl peroxide 154 Tert-butyl cumyl peroxide 159
2,5-Dimethyl-2,5-bis-(tert- 164 butyl peroxy)3-hexyne
[0048] In a further embodiment, some additional second peroxides
that can be used in addition to one or more of the above described
second peroxides can include but are not limited to tert-butyl
peroxy acetate, di-tert-amyl peroxide, bis-(tert-butyl
peroxyisopropyl)benzene, 2,5-dimethyl-2,5-bis-(tert-butyl
peroxy)hexane and di-tert-butyl peroxide, as well as any peroxide
that is conventionally used or known. In one embodiment herein,
second peroxide can comprise the combination of any of the herein
described second peroxides. In the system of peroxides herein at
least one first peroxide and at least one second peroxide are
different peroxides.
[0049] In another embodiment herein the above described composition
comprising one or more unsaturated silane compounds of the Formulae
(1) and/or (2) and the system of at least two peroxides, can
further comprise one or more thermoplastic polymers. The
thermoplastic polymer used herein is a crosslinkable thermoplastic
polymer.
[0050] The thermoplastic polymer can be a polyolefin, such as, one
or more .alpha.-olefins, .alpha.-olefin copolymers, .alpha.-olefin
terpolymers and mixtures thereof. In one more specific embodiment,
the thermoplastic polymer comprises one or more polyolefins wherein
the one or more polyolefins are polyethylene polymers or
copolymers.
[0051] Some non-limiting examples of polyolefins that can be used
herein include high-pressure low-density polyethylene,
medium/low-pressure high-density polyethylene, low-pressure
low-density polyethylene, medium-density polyethylene, an
ethylene-.alpha.-olefin copolymer, polypropylene, an ethylene-ethyl
acrylate copolymer, an ethylene-vinyl acetate copolymer, an
ethylene-propylene copolymer, an ethylene-propylene-diene
terpolymer, an ethylene-butene copolymer,
polymethylpentenepolybutene, chlorinated polyethylene, an
ethylene-vinyl acetate-chlorine terpolymer, and the like, and
mixtures thereof.
[0052] In one more embodiment herein, the herein described
composition comprising one or more unsaturated silane compounds of
the Formulae (1) and/or (2), the system of at least two peroxides
and a thermoplastic polymer can further optionally comprise one or
more additional components capable of inhibiting silane grafting
and/or crosslinking during storage. In one embodiment herein, any
of the compositions herein can be stored in the absence of
moisture. The compositions herein can further comprise one or more
additional components capable of inhibiting silane grafting and/or
crosslinking during storage wherein said additional components are
such as the non-limiting examples of a free-radical inhibitor,
free-radical stabilizer and/or free-radical scavenger. Some
specific non-limiting examples of free-radical inhibitors are
selected from the group consisting of phosphite, such as the
non-limiting examples of tris-2,4-di-tert-butylphenyl)phosphite,
tris-[2,4-di-(1,1-dimethylpropyl)phenyl]phosphite,
tris-(2-phenylphenyl)phosphite, tris(2-cyclohexylpehnyl)phosphite;
single 2,6-dialkylphenols, such as the non-limiting examples of
2,6-di-tert-butyl-4-methoxyphenol,
2,6-di-tert-butyl-4-methoxymethylphenol; bisphenols, such as the
non-limiting examples of
2,2'-methylene-bis-(6-tert-butyl-4-methylphenol),
2,2'-methylene-bis-(6-tert-butyl-4-ethylphenol),
2,2'-methylene-bis-[4-methyl-6-(alpha-methylcyclohexyl)phenol],
1,1-bis-(5-tert-butyl-4-hydroxy-2-methylphenyl)butane,
2,2-bis-(3,5-tert-butyl-4-hydroxyphenyl)propane; and hydroxyphenyl
aromatics, such as the non-limiting examples of
1,3,5-tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethoxybenzene,
dioctadecyl 2,2-bis-(3,5-di-tert-butyl-4-hydroxybenzyl)malonate,
pentaerythrilyl [3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate],
stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and
combinations thereof. Other free-radical inhibitors are disclosed
in U.S. Pat. No. 4,187,212 which is incorporated herein by
reference in its entirety. Some specific non-limiting examples of
free-radical scavengers are selected from the group consisting of
pentaerythrilyl [3-(3,5-di-tert-butyl-4-hydroxypehneyl)propionate],
stearyl 3-(3,5-di-tert-butyl-4-hydroxypehneyl)propionate and
tris-2,4-di-tert-butylphenyl)phosphate and combinations thereof. In
one other embodiment herein, the compositions herein can further
comprise moisture, which can be present as indicated herein.
[0053] In another embodiment herein, the composition described
herein further comprises optionally one or more crosslinking
catalysts which accelerate the hydrolysis of the alkoxysilyl groups
and/or condensation of the resulting silanol groups that are
graphed onto thermoplastic polymer; and, still even further
optionally, additives such as the non-limiting examples of
antioxidants, processing aids, oils, plasticizers, fillers,
colorants, pigments and lubricants.
[0054] A wide variety of materials which function as crosslinking
catalysts for silanes are known in the art and any of such
materials may be employed herein. Some non-limiting examples of
crosslinking catalysts include metal carboxylates such as
dibutyltin dilaurate, stannous acetate, stannous octanoate, lead
naphthenate, zinc octanoate, iron-2-ethylhexanoate and cobalt
naphthenate; organic metal compounds such as the titanium esters
and chelates, for example tetra-butyl titanate, tetra-nonyl
titanate and bis-(acetylacetonyl)di-isopropyl titanate; organic
bases such as ethylamine, hexylamine, dibutylamine and piperidine;
and acids such as the mineral acids and fatty acids; and
combinations of any of the foregoing crosslinking catalysts.
Crosslinking catalysts are more specifically, the organic tin
compounds, for example, the non-limiting examples of dibutyltin
dilaurate, dibutyltin diacetate, dibutyltin dioctanoate, and
combinations thereof.
[0055] In one specific embodiment herein, there is provided a
composition comprising:
[0056] (i) one or more silane compounds according to the Formula
(1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group, or alternatively each of
X.sup.1 and X.sup.2 is a hydrolyzable group having a direct bond to
the silicon atom and also simultaneously a direct bond to each
other to form a ring containing the silicon atom of the unsaturated
silane of Formula (1);
[0057] (ii) a system of at least two peroxides comprising a first
peroxide having a first 0.1 hour half-life temperature and a second
peroxide having a second 0.1 hour half-life temperature, the first
and second 0.1 hour half-life temperatures in said composition
having a temperature differential of at least about 5.degree. C.;
and
[0058] (iii) one or more thermoplastic polymers;
the composition optionally containing one or more additional
components capable of inhibiting silane grafting and/or
crosslinking during storage.
[0059] In another embodiment herein, there is provided a
composition comprising:
[0060] (i) one or more unsaturated silane compounds according to
the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring containing a silicon atom of the unsaturated silane of
Formula (1);
[0061] (ii) a system of at least two peroxides comprising a first
peroxide having a first 0.1 hour half-life temperature and a second
peroxide having a second 0.1 hour half-life temperature, the first
and second 0.1 hour half-life temperatures in said composition
having a temperature differential of at least about 5.degree.
C.;
[0062] (iii) one or more thermoplastic polymers; and
[0063] (iv) one or more crosslinking catalysts;
the composition optionally containing one or more additional
components capable of inhibiting silane grafting and/or
crosslinking during storage and/or optionally at least one
additive.
[0064] In one specific embodiment herein, there is provided a
silane-grafted thermoplastic polymer comprising a thermoplastic
polymer grafted to one or more unsaturated silane compounds
according to a process comprising subjecting a composition
comprising (i) one or more unsaturated silane compounds, (ii) a
system of at least two peroxides, and (iii) one or more
thermoplastic polymers, to conditions suitable for grafting of the
unsaturated silane compound to the thermoplastic polymer to form a
silane-grafted thermoplastic polymer wherein:
the one or more unsaturated silane compounds are according to the
Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and the system of at least two peroxides comprise a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C.
[0065] In another embodiment herein, there is provided a process
for producing a silane-grafted thermoplastic polymer, the process
comprising subjecting a composition comprising (i) one or more
unsaturated silane compounds, (ii) a system of at least two
peroxides, and (iii) one or more thermoplastic polymers, such as
those described herein, to conditions suitable for grafting of the
unsaturated silane compound to the thermoplastic polymer to form a
silane-grafted thermoplastic polymer, wherein:
the one or more unsaturated silane compounds are according to the
Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); and the system of at least two peroxides comprising a
first peroxide having a first 0.1 hour half-life temperature and a
second peroxide having a second 0.1 hour half-life temperature, the
first and second 0.1 hour half-life temperatures in said
composition having a temperature differential of at least about
5.degree. C. In one embodiment herein it will be understood that
any of the temperature differentials described herein can be used
in any embodiment herein that utilizes a system of at least two
peroxides as herein described. In another embodiment herein, the
process(es) of producing a silane-grafted thermoplastic polymer can
further comprise subjecting the silane-grafted thermoplastic
polymer to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer to produce a crosslinked
thermoplastic polymer. The conditions suitable for grafting of the
crosslinkable unsaturated silane compound to the thermoplastic
polymer comprise subjecting the crosslinkable formulation to a
reaction temperature between about a melting temperature and about
a degradation temperature of the thermoplastic polymer for a period
of time suitable for the at least partial grafting of the
crosslinkable unsaturated silane compound to the thermoplastic
polymer. The aforementioned reaction temperature and/or any
reaction temperature described herein can be in a range of
specifically about 140.degree. C. to about 260.degree. C., more
specifically about 160.degree. C. to about 250.degree. C. and most
specifically about 180.degree. C. to about 240.degree. C.; and said
period of time is specifically of from about 0.5 to about 10
minutes, more specifically of from about 1 to about 7 minutes and
most specifically of from about 2 to about 5 minutes. In yet
another embodiment herein, the conditions suitable for crosslinking
of the silane-grafted thermoplastic polymer comprise subjecting the
silane-grafted thermoplastic polymer to moisture and a crosslinking
catalyst, such as the crosslinking catalysts described herein. The
thermoplastic polymer in the process(es) herein can be any one or
more of the herein described thermoplastic polymers. The
unsaturated silane compound of Formula (1) in the process(es)
described herein can specifically be any one or more of the herein
described unsaturated silane compounds. The unsaturated silane
compound of Formula (1) in the process(es) described herein can be
any one or more of the unsaturated silane compounds of the Formula
(2) as described herein. In another embodiment herein, the system
of at least two peroxides described in any of the process(es)
herein can be any one or more of the herein described system(s) of
peroxides, and more specifically can contain temperature
differentials between the first and second 0.1 hour half-life
temperatures of the first and second peroxides in the herein
described ranges. In a further embodiment, the first and second
peroxides described in any of the process(es) herein can be any one
or more of the herein described first and second peroxides
respectively. In a further embodiment herein, any of the components
present in the composition described herein can likewise be present
in the process(es) and article(s) described herein.
[0066] In yet a further specific embodiment herein, there is
provided a process for producing a crosslinked thermoplastic
polymer, the process comprising: a) subjecting a composition
comprising (i) one or more unsaturated silane compounds, (ii) a
system of at least two peroxides, and (iii) one or more
thermoplastic polymers, such as those described herein, to
conditions suitable for grafting of the unsaturated silane compound
to the thermoplastic polymer to form a silane-grafted thermoplastic
polymer; and b) subjecting the silane-grafted thermoplastic polymer
of step (a) to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer to produce a crosslinked
thermoplastic polymer; wherein: the one or more unsaturated silane
compounds are according to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring containing the silicon atom of the silane, such as the
unsaturated silane compound of Formula (1); the system of at least
two peroxides comprises a first peroxide having a first 0.1 hour
half-life temperature and a second peroxide having a second 0.1
hour half-life temperature, the first and second 0.1 hour half-life
temperatures in said composition having a temperature differential
of at least about 5.degree. C., or any of the other temperature
differentials described herein; the conditions for silane grafting
according to step (a) and for crosslinking according to step (b)
are the same or different, such as the conditions for silane
grafting and crosslinking described herein, and optionally in one
embodiment wherein steps (a) and (b) are conducted simultaneously
or consecutively. The process(es) herein enables the crosslinking
of thermoplastic polymer to be carried out under less critical
processing conditions, such as controlling the temperature and
residence time in a very narrow range, than those which are
normally obtained in connection with conventional peroxide
crosslinking techniques.
[0067] The process(es) herein therefore lends itself to the
preparation of a crosslinked thermoplastic polymer in conventional
extrusion equipment and under conditions and in a time comparable
to those normally employed for the compounding of such materials.
The improved grafting efficiency of the present disclosure
decreases the requirement for expensive silane and peroxide.
[0068] In another embodiment, the present disclosure is directed to
a process(es) for crosslinking thermoplastic polymers under
reactive mechanical-working conditions that will minimize the
occurrence of gel formation, screw-buildup and/or scorching during
processing step (a) as described herein while maintaining high
crosslinking efficiency. Any of the herein described process(es)
can be conducted under reactive mechanical-working conditions and
compositions described herein can be used in such processes and
articles as described herein under reactive mechanical-working
conditions.
[0069] In another embodiment, the present disclosure is directed to
a process for crosslinking thermoplastic polymers under reactive
mechanical-working conditions comprising: a) subjecting a
crosslinkable formulation comprising (i) one or more unsaturated
silane compounds, (ii) a system of at least two peroxides, and
(iii) one or more thermoplastic polymers, to conditions suitable
for grafting of the unsaturated silane compound to the
thermoplastic polymer to form a silane-grafted thermoplastic
polymer; and
[0070] b) subjecting the silane-grafted thermoplastic polymer of
step (a) to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer to form a crosslinked
thermoplastic polymer;
wherein: the one or more unsaturated silane compounds are according
to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring with the silicon atom of the unsaturated silane of
Formula (1); the system of at least two peroxides comprise a first
peroxide having a 0.1 hour first half-life temperature and a second
peroxide having a second 0.1 hour half-life temperature, the first
and second 0.1 hour half-life temperatures in said composition
having a temperature differential of at least about 5.degree. C.;
and wherein the conditions for silane grafting according to step
(a) and for crosslinking according to step (b) are the same or
different, and optionally in one embodiment, wherein steps (a) and
(b) are conducted simultaneously or consecutively.
[0071] In one embodiment, the present disclosure employs a system
of at least two peroxides possessing a range of 0.1 hour half-life
temperatures such that undesired early and/or concentrated
activation of the peroxides is decreased; and the broad range of
half-life temperature allows for a controlled level of activation
and grafting throughout the reactive process which leads to an
improved level of grafting efficiency of the unsaturated silane
compound to the thermoplastic polymer. In a further embodiment, in
addition, the use of peroxides containing a range of 0.1 hour
half-life temperatures reduces the level of gel formation, screw
buildup and/or scorching allowing for extended run-times.
[0072] In one embodiment herein, in accordance with the process of
this disclosure, the reaction between the thermoplastic polymer and
the silane is carried out employing any suitable mechanical-working
apparatus heretofore employed in the processing of thermoplastic
polymers, e.g., a screw-type extruder, an internal Banbury mixer or
a roll mill, provided, of course, that it results in bringing the
composition to grafting temperature. The more specific apparatus
for use in providing the crosslinkable polyolefin silane-graphed
thermoplastic polymer of this disclosure is an extruder adapted to
effect a kneading or compounding action on its contents. Such
extruder apparatus may include such optional features as a heating
jacket to augment the heat produced within the extruder barrel and
a vacuum port whereby any unreacted silane and volatile components,
such as decompositon products of the peroxide, alcohol, and the
like, can be removed.
[0073] In one embodiment herein, the thermoplastic polymer,
unsaturated silane compound(s), system of at least two peroxides
and other components can be brought together by any convenient
means. For example, the silane can be introduced into the apparatus
in which the reaction is to take place dispersed on the surface of
the thermoplastic polymer or it can be metered directly into the
apparatus. The system of at least two peroxides can also be
introduced by way of the surface of the thermoplastic polymer and,
when possible, dissolved in the silane. The silane and/or peroxide
components can also be introduced as "dry-silanes", which are
unsaturated silanes of Formula (1), and/or at least two peroxides
and optionally other additional components and/or additives of the
composition(s), and/or process(es) and/or articles described herein
which are absorbed on suitable mineral or organic carriers.
[0074] In one embodiment herein, reaction between the unsaturated
silane and thermoplastic polymer can be carried out at any suitable
temperature between about the melting and about the degradation
temperature of the polyolefin. The actual reaction temperature
employed will normally be determined by considerations of the type
of apparatus in which the reaction is performed and where
appropriate on the power input for the apparatus and the compound
viscosity profile. When the thermoplastic polymer is polyethylene,
it is desirable to perform the reaction at temperatures similar to
those usually met during the processing of polyethylene, such as
those temperatures and times described herein.
[0075] In one embodiment, crosslinking of thermoplastic polymer
according to the process of this disclosure is accomplished in the
presence of moisture. The moisture present in the atmosphere is
usually sufficient to permit the crosslinking to occur but the rate
of crosslinking may be hastened if desired by the use of an
artificially moistened and optionally heated atmosphere, steam or
liquid water.
[0076] In one embodiment, the present disclosure is applicable to
all processes used for the manufacturing of silane crosslinkable
compounds or products where the silane is grafted onto the polymer
backbone using radical grafting. Some such non-limiting processes
include the One-Step Monosil process, the One-Step XL-PEarl
process, the One-Step Spherisil P process, the Two-Step Sioplas
process, the One-Step Soaking process and combinations thereof.
[0077] In one embodiment, while any conventional method can be used
to graft the unsaturated silane to the thermoplastic polymer, one
specific method is blending the thermoplastic polymer(s) with the
system of at least two peroxides and unsaturated silane in the
first stage of a reactor extruder, such as a single screw extruder,
specifically one with a length/diameter (L/D) ratio of specifically
of about 25:1 or greater, more specifically of about 30:1 or
greater and most specifically of about 38:1 or greater. The
grafting conditions can vary greatly depending on the compound
formulation, but the melt temperatures are specifically between
about 160.degree. and about 240.degree. C., more specifically
between about 210.degree. and about 230.degree. C., and most
specifically between about 200.degree. C. and about 220.degree. C.
depending upon the residence time and the half-life of the
peroxides.
[0078] In one embodiment herein, the articles prepared from the
crosslinked compositions of this disclosure can be filled or
unfilled. If filled, then the amount of filler present should not
exceed an amount that would cause degradation of the properties of
interest in crosslinked composition, such as the herein-noted
properties of reduced scorch, reduced gel formation, reduced screw
buildup, improved melt index, and the like. The amount of filler
present is specifically between from about 0.1 and about 80 weight
percent, and more specifically between about 20 and about 60 weight
percent based on the total weight of the composition. Some
representative fillers include the non-limiting examples of kaolin
clay, magnesium hydroxide, aluminum trihydroxide, silica and
calcium carbonate. When filler is present, the filler can be coated
with a material that will prevent or retard any tendency that the
filler might otherwise have to interfere with the silane cure
reaction. Stearic acid or silane coupling agents are non-limiting
examples of such a filler coating.
[0079] In one embodiment herein there is provided an article,
produced by a process comprising: a) providing a composition
comprising: (i) one or more unsaturated silane compounds according
to the Formula (1):
G.sup.1R.sup.1SiX.sup.1X.sup.2 (1)
wherein G.sup.1 is an olefinically unsaturated hydrocarbon group,
optionally heteroatom-substituted with one or more oxygen and/or
nitrogen atoms; R.sup.1 is selected from the group consisting of
alkyl, aryl, aralkyl and arenyl; each of X.sup.1 and X.sup.2 is
independently a hydrolyzable group or alternatively each of X.sup.1
and X.sup.2 is a hydrolyzable group having a direct bond to the
silicon atom and also simultaneously a direct bond to each other to
form a ring containing the silicon atom of the unsaturated silane
of Formula (1), such as in Formula (2) described herein; (ii) a
system of at least two peroxides comprising a first peroxide having
a first 0.1 hour half-life temperature and a second peroxide having
a second 0.1 hour half-life temperature, or any one or more of the
other systems of peroxides described herein, the first and second
0.1 hour half-life temperatures in said composition having a
temperature differential of at least about 5.degree. C.; and (iii)
one or more thermoplastic polymers, such as any of the herein
described thermoplastic polymers;
[0080] b) subjecting the composition of step (a) to conditions
suitable for grafting of the unsaturated silane compound to the
thermoplastic polymer to form a silane-grafted thermoplastic
polymer, such as those described herein;
[0081] c) subjecting the silane-grafted thermoplastic polymer of
step (b) to conditions suitable for crosslinking of the
silane-grafted thermoplastic polymer, such as those described
herein, to form a crosslinked thermoplastic polymer; and,
[0082] d) producing the article therefrom before, and/or during
and/or after conducting step (c),
wherein the conditions for silane grafting according to step (b)
and for crosslinking according to step (c) are the same or
different, and optionally in one embodiment, wherein steps (b) and
(c) are conducted simultaneously or consecutively.
[0083] The article described herein can be a molded article wherein
the composition can be more specifically provided to a mold after
subjecting the composition to grafting conditions and before
subjecting the composition to crosslinking conditions.
[0084] In one embodiment, additives can be used in the preparation
of and be present in the articles prepared from the crosslinked
thermoplastic compositions described herein, and includes the
non-limiting examples of antioxidants, processing aids, oils,
plasticizers, colorants, pigments and lubricants.
[0085] In one embodiment, the amounts of the components described
herein can vary greatly depending on the nature of the
thermoplastic polymer (e.g. polyolefin) and other components and
the process of production of articles made from the crosslinked
thermoplastic polymers (e.g., silane crosslinked polyolefin(s)).
The unsaturated silane of the general Formula (1) can comprise of
specifically of from about 0.1 to about 10 weight percent, more
specifically of from about 0.3 to about 3 weight percent and most
specifically of from about 0.5 to about 2.0 weight percent based
upon the total weight of the composition (crosslinkable
formulation) containing the thermoplastic polymer, unsaturated
silane, at least two peroxides and optionally the catalyst(s),
stabilizer(s), processing aid(s) and metal deactivator(s). The
unsaturated silane of the general Formula (2) can be present in the
amount described above for Formula (1). It will be understood
herein that Formula (2) is a more specific embodiment of Formula
(1).
[0086] In one embodiment, the system of at least two peroxides will
vary in amount as described above, depending on the desired range
of peroxide half-life temperatures and times. The amount of the
system of at least two peroxides can be varied over a wide range,
such as the non-limiting examples, of from about 0.01 to about 0.4
weight percent, more specifically from about 0.02 to about 0.2
weight percent and most specifically from about 0.05 to about 0.1
weight percent, based upon the total weight of the composition
(crosslinkable formulation) containing the thermoplastic polymer,
unsaturated silane, at least two peroxides and optionally the
catalyst(s), stabilizer(s), processing aid(s) and metal
deactivator(s).
[0087] In one embodiment herein the amount of thermoplastic polymer
in the composition (crosslinkable formulation) comprising polymer,
unsaturated silane, at least two peroxides and optionally the
catalyst(s), stabilizer(s), processing aid(s) and metal
deactivator(s) can comprise specifically of from about 97.0 to
about 99.8 weight percent, more specifically of from about 97.5 to
about 99.5 weight percent and most specifically of from about 98.0
to about 99 weight percent based on the total weight of the
composition (crosslinkable formulation).
[0088] In one embodiment, the catalyst(s) used to accelerate the
crosslinking of the silane-graphed thermoplastic polymer, if
utilized herein, will typically be present in the amount of from
0.01 to about 1.0 weight percent, more specifically from 0.05 to
about 0.5 weight percent and most specifically from about 0.1 to
about 0.2 weight percent, based upon the total weight of the
composition (crosslinkable formulation) containing the
thermoplastic polymer, unsaturated silane, at least two peroxides,
catalyst(s) and optionally the, stabilizer(s), processing aid(s)
and metal deactivator(s).
[0089] In one embodiment, the unsaturated silane(s) of Formula (1)
and system of at least two peroxides will be premixed to form a
mixture, optionally containing the catalyst(s), stabilizer(s),
processing aid(s) and metal deactivator(s), and this mixture of
will be used at loading levels of specifically from about 0.1 to
about 10, more specifically of from about 0.3 to about 3 and most
specifically of from about 0.5 to about 2.0 weight percent of the
total composition (crosslinkable formulation) containing the
thermoplastic polymer, unsaturated silane, at least two peroxides
and optionally the catalyst(s), stabilizer(s), processing aid(s)
and metal deactivator(s).
[0090] The mixture comprising the silane(s) for Formula (1), system
of at least two peroxides and optionally containing the
catalyst(s), stabilizer(s), processing aid(s) and metal
deactivator(s), shall specifically be characterized by the
unsaturated silane being present in amounts of specifically from
about 50 to about 99 weight percent, more specifically from about
75 to about 95 weight percent and most specifically of from about
85 to about 92 weight percent of the total mixture. The amount of
peroxides that are pre-blended to form a mixture with the
unsaturated silane of Formula (1) and optionally the catalyst(s),
stabilizer(s), processing aid(s) and metal deactivator(s) will be
in total weight of the mixture of specifically from about 0.5 to
about 15 weight percent and more specifically from about 2 to about
8 weight percent, and most specifically of from about 3 to about 5
weight percent. In one embodiment, the level of crosslinking
catalysts will vary in amount as described above, depending on the
desired rate for crosslinking silane-graphed thermoplastic polymer.
Specifically, herein the crosslinking catalysts can be present in
the mixture of unsaturated silane, at least two peroxides and
optionally stabilizer(s), processing aid(s) and metal
deactivator(s) in an amount of specifically from 0.001 to about 10
weight percent, more specifically of from about 0.5 to about 5
weight and most specifically of from about 1.0 to about 2.0 weight
percent based on the total weight of the mixture. The amount of one
or more peroxide inhibitors and/or stabilizers in the mixture of
unsaturated silane, at least two peroxides and optionally the
catalyst(s), processing aid(s) and metal deactivator(s) can
comprise specifically of from about 0.1 to about 10 weight percent,
more specifically of from about 1.0 to about 5.0 weight percent and
most specifically of from about 2.0 to about 3.0 weight percent
based on the total weight of the mixture.
[0091] In one embodiment herein the total level of additives,
including processing aids and metal deactivators, in the mixture of
unsaturated silane, at least two peroxides and optionally the
catalyst(s), and stabilizer(s), as described above, can each
specifically be included, in amounts of specifically from about
0.001 to about 25 weight percent, more specifically of from about
0.5 to about 5 weight percent and most specifically of from about
1.0 to about 3.0 weight percent, based on the total weight of the
mixture.
[0092] In one embodiment, the mixture comprising the unsaturated
silane of Formula (2), the system of at least two peroxides, and
optionally containing the catalyst(s), stabilizer(s), processing
aid(s) and metal deactivator(s) shall specifically be characterized
by the unsaturated silane being present in amounts of specifically
from about 50 to about 99 weight percent, more specifically from
about 75 to about 95 weight percent and most specifically of from
about 85 to about 92 weight percent of the total mixture. In
another embodiment herein, the amount of peroxides that are
pre-blended to form a mixture with the unsaturated silane of
Formula (1) and optionally the catalyst(s), stabilizer(s),
processing aid(s) and metal deactivator(s) will be in total weight
of the mixture of specifically from about 0.5 to about 15 weight
percent and more specifically from about 2 to about 8 weight
percent, and most specifically of from about 3 to about 5 weight
percent. In one embodiment, the level of crosslinking catalysts
will vary in amount as described above, depending on the desired
rate for crosslinking silane-graphed thermoplastic polymer.
Specifically, in one embodiment herein the crosslinking catalysts
can be present in the mixture of unsaturated silane, at least two
peroxides and optionally stabilizer(s), processing aid(s) and metal
deactivator(s) in an amount of specifically from 0.001 to about 10
weight percent, more specifically of from about 0.5 to about 5
weight and most specifically of from about 1.0 to about 2.0 weight
percent based on the total weight of the mixture. In one embodiment
said mixture can further comprise peroxide inhibitor in the amount
of one or more peroxide inhibitors and/or stabilizers in the
mixture of unsaturated silane, at least two peroxides and
optionally the catalyst(s), processing aid(s) and metal
deactivator(s) can comprise specifically of from about 0.1 to about
10 weight percent, more specifically of from about 1.0 to about 5.0
weight percent and most specifically of from about 2.0 to about 3.0
weight percent based on the total weight of the mixture. In one
embodiment herein the total level of additives, including
processing aids and metal deactivators, in the mixture of
unsaturated silane, at least two peroxides and optionally the
catalyst(s), and stabilizer(s), as described above, can each
specifically be included, in amounts of specifically from about
0.001 to about 25 weight percent, more specifically of from about
0.5 to about 5 weight percent and most specifically of from about
1.0 to about 3.0 weight percent, based on the total weight of the
mixture.
[0093] In one embodiment, a mixture comprising the unsaturated
silane of Formula (2), a single (first or second) peroxide and
optionally catalyst(s), stabilizer(s), processing aid(s) and metal
deactivator(s) can have better shelf stability. This mixture having
only one peroxide (first or second) achieves better
shelf-stability, because the stabilizer(s) used to prevent
premature activation of the peroxide can be specifically chosen to
match the reactivity of the single peroxide in the mixture. The
remaining peroxide not yet used (first or second depending on which
was used first) of the at least two peroxides can be added to the
mixture just prior to use or added to the mechanical working
apparatus separately from the mixture containing the silane, the
single peroxide (first or second) and other optional additional
components or additives as described herein, wherein in the
situation of the addition of the remaining peroxide to the
mechanical working apparatus would then comprise the composition as
described herein.
[0094] In one embodiment, the mixture comprising the unsaturated
silane of Formula (2), a single peroxide (first or second), and
optionally the catalyst(s), stabilizer(s), processing aid(s) and
metal deactivator(s) shall specifically be characterized by the
unsaturated silane being present in amounts of specifically from
about 50 to about 99 weight percent, more specifically from about
75 to about 95 weight percent and most specifically of from about
85 to about 92 weight percent of the total mixture. In another
embodiment herein, the amount of a single peroxide (first or
second) that is pre-blended to form a mixture with the unsaturated
silane of Formula (2) and optionally the catalyst(s),
stabilizer(s), processing aid(s) and metal deactivator(s) will be
in total weight of the mixture of specifically from about 0.5 to
about 15 weight percent and more specifically from about 2 to about
8 weight percent, and most specifically of from about 3 to about 5
weight percent. In one embodiment, the level of crosslinking
catalyst will vary in amount as described above, depending on the
desired rate for crosslinking silane-graphed thermoplastic polymer.
Specifically, in one embodiment herein the crosslinking catalysts
can be present in the mixture of unsaturated silane, the single
peroxide (first or second) and optionally stabilizer(s), processing
aid(s) and metal deactivator(s) in an amount of specifically from
0.001 to about 10 weight percent, more specifically of from about
0.5 to about 5 weight and most specifically of from about 1.0 to
about 2.0 weight percent based on the total weight of the mixture.
In one embodiment the amount of one or more peroxide inhibitors
and/or stabilizers in the mixture of unsaturated silane, a single
peroxide (first or second) and optionally the catalyst(s),
processing aid(s) and metal deactivator(s) can comprise
specifically of from about 0.1 to about 10 weight percent, more
specifically of from about 1.0 to about 5.0 weight percent and most
specifically of from about 2.0 to about 3.0 weight percent based on
the total weight of the mixture. In one embodiment herein the total
level of additives, including processing aids and metal
deactivators, in the mixture of unsaturated silane, a single
peroxide (first or second) and optionally the catalyst(s), and
stabilizer(s), as described above, can each specifically be
included, in amounts of specifically from about 0.001 to about 25
weight percent, more specifically of from about 0.5 to about 5
weight percent and most specifically of from about 1.0 to about 3.0
weight percent, based on the total weight of the mixture. It will
be understood herein that mixture comprising only one peroxide
(first or second) as described herein will have the remaining
peroxide (first or second respectively) added prior to the
formation of the composition as it is understood herein.
[0095] In one embodiment herein, the compositions, processes and
articles described herein can be used in wire and cable insulation,
weatherstripping, fibers, seals, gaskets, foams, footware, flexible
tubing, pipes, bellows, tapes and combinations thereof as well as
other applications.
[0096] The following examples are illustrative of the process
herein for preparing unsaturated silanes of Formula (2), for
preparing mixtures of unsaturated silanes, systems of peroxides,
and optionally catalysts, stabilizer(s), processing aid(s) and
metal deactivator(s), for preparing compositions (crosslinkable
formulations) containing unsaturated silanes, systems of peroxides,
thermoplastic polymers and optionally catalysts, stabilizer(s),
processing aid(s) and metal deactivator(s) and crosslinked
compositions of thermoplastic polymers.
EXAMPLE 1
[0097] 2,4,4,6-Tetramethyl-2-vinyl-[1,3,2]dioxasilinane can be
prepared by adding vinylmethyldimethoxysilane (132.2 grams, 1.0
mole) into a 500 ml round bottom flask. Sulfuric acid (0.47 grams)
can be added to the reaction flask and 2-methyl-2,4-pentanediol
(118.2 grams, 1 mole) can be added using an addition funnel. The
flask can be heated to 50.degree. C. under a vacuum of 50 torr.
Methanol can then be collected. A 21% ethanolic solution of sodium
ethoxide (3.5 grams) is added to neutralize the acid and then
stripped under reduced pressure to remove any ethanol that may be
present.
EXAMPLE 2
[0098] An extrusion molding grade of polyethylene pellets (Escorene
LD 166 BA, available from Exxon Mobile Chemical Company) having a
melt flow index of 0.2 g/10 min at 190.degree. C. under a load of
2.16 kg and density of 0.922 g/cm.sup.3 (100 parts by weight
polymer) can be coated by tumbling with a mixture (1.2 parts by
weight polymer) composed of 92.0 weight percent
vinylmethyldimethoxysilane 2.5 weight percent 1,1-bis-(tert-butyl
peroxy)-3,3,5-trimethylcyclohexane having a 0.1 hour half-life
temperature of 128.degree. C., 2.5 weight percent di-tert-butyl
peroxide having a 0.1 hour half-life temperature of 164.degree. C.
and 3 weight percent dibutyltin dilaurate crosslinking catalyst,
until all of the liquid is taken up. The composition can then be
extruded in a single screw extruder under the following
conditions:
[0099] Temperature of screw: 60.degree. C.
[0100] Temperature of barrel zone 1: 170.degree. C.
[0101] Temperature of barrel zone 2: 220.degree. C.
[0102] Screw speed: 20 rotations per minute (rpm)
[0103] The residence time of the polyethylene in the machine can be
approximately 1 to 2 minutes.
EXAMPLE 3
[0104] A composition (crosslinkable formulation) can be prepared by
mixing 9.88 kilograms of polyethylene and 0.12 kilograms of a
mixture composed of unsaturated silane, two peroxides and a
catalyst. The base polyethylene resin can be Escorene LD 166 BA,
available from Exxon Mobile Chemical Company with a melt flow index
of 0.2 g/10 min at 190.degree. C. under a load of 2.16 kg, and a
density of 0.922 g/dm.sup.3. The mixture can be prepared by
charging 111 grams of the silane from Example 1 into a 250 ml three
neck round bottom flask equipped with a mechanical stirrer, dry
nitrogen line and funnel. To which can be added 1,1-bis-(tert-butyl
peroxy)-3,3,5-trimethylcyclohexane having a 0.1 hour half-life
temperature of 128.degree. C. (2.8 grams), di-tert-butyl peroxide
having a 0.1 hour half-life temperature of 164.degree. C. (2.8
grams) and dibutyltin dilaurate (3.3 grams) slowly with
stirring.
[0105] The mixture of reactants can be pre-soaked onto the polymer
pellets prior to feeding into the extruder by mixing at room
temperature for 4 hours. The thermoplastic polymer formulation can
then be extruded on a Troester single screw extruder equipped with
a barrier screw of a diameter of 45 millimeters (mm) and a length
of 25 L/D. A breaker plate can be absent and the screw speed can be
set at 20 rotations per minute (rpm). The feeding zone and screw
can then be respectively cooled to 50.degree. C. and 60.degree. C.
The barrel temperatures can be set at 150.degree. C. for the first
zone with a regular temperature increase in each of the zones so
that the temperature in the last zone is 220.degree. C. The
resulting melt temperature can then be measured in the polymer.
EXAMPLE 4
[0106] A composition (crosslinkable formulation) can be prepared by
mixing 10.40 kilograms of polyethylene, 0.35 kilograms of a carbon
black (N339 available from Continental Carbon) and 0.12 kilograms
of a mixture composed of unsaturated silane, two peroxides,
stabilizer and catalyst. The base polyethylene resin can be
Escorene LD 166 BA, available from Exxon Mobile Chemical Company
with a melt flow index of 0.2 g/10 min at 190.degree. C. under a
load of 2.16 kg, and a density of 0.922 g/dm.sup.3. The mixture can
be prepared by charging 108 grams of the silane from Example 1 into
a 250 ml three neck round bottom flask equipped with a mechanical
stirrer, dry nitrogen and funnel.
1,3,5-Trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene
(3.0 grams), bis-2,4-dichlorobenzoyl)peroxide have a 0.1 hour
half-life of 93.degree. C. (2.8 grams), tert-butyl cumyl peroxide
having a 0.1 hour half-life of 154.degree. C. (2.8 grams) and
dibutyltin dilaurate (3.3 grams) can then be slowly added with
stirring. The mixture of reactants can be pre-soaked onto the
polymer pellets prior to feeding into the extruder by mixing at
room temperature for 4 hours. The thermoplastic polymer formulation
can then be extruded on a Troester single screw extruder equipped
with a barrier screw of a diameter of 45 millimeters (mm) and a
length of 25 L/D. A breaker plate can be absent and the screw speed
can be set at 20 rotations per minute (rpm). The feeding zone and
screw can be respectively cooled to 50.degree. C. and 60.degree. C.
The barrel temperatures can be set at 150.degree. C. for the first
zone with a regular increase in each of the zones so that the
temperature in the last zone is 220.degree. C. The resulting melt
temperature can then be measured in the polymer. The crosslinkable
silane-graphed thermoplastic can then be extruded through a die at
the end of the single screw extruder to form a pipe.
[0107] The pipe composed of the crosslinkable silane-graphed
thermoplastic polymer can then then soaked in 80.degree. C. water
for 48 hours to form the crosslinked article.
EXAMPLE 5
[0108] A shelf-stable mixture containing only a single peroxide can
be prepared by charging 108 grams of the silane from Example 1 into
a 250 ml three neck round bottom flask equipped with a mechanical
stirrer, dry nitrogen line and funnel.
1,3,5-Trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene
(3.0 grams), tert-butyl cumyl peroxide having a 0.1 hour half-life
of 154.degree. C. (5.6 grams) and dibutyltin dilaurate (3.3 grams)
can be slowly added with stirring. The mixture can then be removed
from the flask and stored under nitrogen in a 250 ml brown bottle.
This mixture can then be mixed with dibenzoyl peroxide have a 0.1
hour half-life of 113.degree. C. (5.6 grams) prior to being
extruded as indicated above.
[0109] While the invention has been described in detail in
connection with specific embodiments thereof, it should be readily
understood that the invention is not limited to such disclosed
embodiments. Rather, the invention can be modified to incorporate
any number of variations, alterations, substitutions or equivalent
arrangements not heretofore described, but which are commensurate
with the spirit and scope of the invention. Accordingly, the
invention is not to be limited by the foregoing description.
* * * * *
References