Process For Preparing A Polypropylene-Based Object Having An Increased Surface Energy
Process for preparing a polypropylene-based object having an increased surface energy The present invention relates to a process for preparing a polypropylene-based object having an increased surface energy, said process comprising the subsequent steps of a) providing a polypropylene resin, b) forming an object of said polypropylene resin, and c) subjecting the surface of the object to a surface energy increasing treatment step, Characterized in that the polypropylene resin comprises A) at least one secondary antioxidant of formula (I) in which n is 0 or 1, each R may be the same or different and is an unsubstituted phenyl group or a phenyl group substituted by one or two alkyl groups having from 1 to 12 carbon atoms, and X is a residue of a monofunctional or difunctional phenyl group, diphenyl group, diphenyl ether group or dibenzofuranyl group and/or of formula (II)
1 . Process for preparing a polypropylene-based object having an increased surface energy, said process comprising the subsequent steps of
a) providing a polypropylene resin,
b) forming an object of said polypropylene resin, and
c) subjecting the surface of the object to a surface energy increasing treatment step,
wherein the polypropylene resin comprises
A) at least one secondary antioxidant
of formula (I)
wherein
n is 0 or 1,
each R may be the same or different and is an unsubstituted phenyl group or a phenyl group substituted by one or two alkyl groups having from 1 to 12 carbon atoms, and
X is a residue of a monofunctional or difunctional phenyl group, diphenyl group, diphenyl ether group or dibenzofuranyl group
and/or of formula (II)
wherein
R 1 is C 12 -C 20 -alkyl or phenyl substituted with C 1 -C 6 -alkyl groups.
2 . Process according to claim 1 , wherein A) is an at least one secondary antioxidant of formula (I).
3 . Process according to claim 1 , wherein A) is an at least one secondary antioxidant of formula (II) in which R 1 is a C 18 H 37 group or is a phenyl group substituted with two tert.-butyl groups.
4 . Process according to claim 1 , wherein the total amount of the at least one secondary antioxidant A ranges from 0.01 wt.-% to 0.5 wt.-%, based on the total weight of the polypropylene resin.
5 . Process according to claim 1 , wherein the polypropylene resin further comprises B) at least one primary antioxidant.
6 . Process according to claim 5 , wherein the total amount of the at least one primary antioxidant B ranges from 0.01 wt.-% to 0.5 wt. %, based on the total weight of the polypropylene resin.
7 . Process according to claim 1 , wherein the polypropylene resin further comprises C) at least one acid scavenger.
8 . Process according to claim 7 , wherein the total amount of the at least one acid scavenger C ranges from 0.05 wt.-% to 0.5 wt.-%, based on the total weight of the polypropylene resin.
9 . Process according to claim 1 , wherein the surface energy increasing surface treatment step involves corona discharge treatment, plasma treatment and/or surface flaming.
10 . Process according to claim 1 , wherein the surface of the object is coated with a layer after the surface energy increasing treatment step.
11 . Polypropylene resin as used in the process according to claim 1 , characterized by
A) at least one secondary antioxidant of formula (I) and/or formula (II).
12 . Composition for use in a polypropylene resin according to claim 11 , characterized by
A) at least one secondary antioxidant of formula (I).
13 . Polypropylene-based object obtainable by the process according to claim 1 , the surface of which having at least 14 days after the surface energy increasing treatment step a dyne level of at least 36 dyne/cm.
14 . Polypropylene-based object according to claim 13 , characterized in that it is in the form of a film.
15 . Multi-layer structure comprising a polypropylene-based object according to claim 14 and a layer applied thereon.
16 . A surface energy retention agent comprising a compound according to formula (I)
wherein
n is 0 or 1,
each R may be the same or different and is an unsubstituted phenyl group or a phenyl group substituted by one or two alkyl groups having from 1 to 12 carbon atoms, and
X is a residue of a monofunctional or difunctional phenyl group, diphenyl group, diphenyl ether group or dibenzofuranyl group
and/or of formula (II)
wherein
R 1 is C 12 -C 20 -alkyl or phenyl substituted with C 1 -C 6 -alkyl groups.
17 . Process according to claim 1 , wherein the total amount of the at least one secondary antioxidant A ranges from 0.03 wt.-% to 0.2 wt.-%, based on the total weight of the polypropylene resin.
18 . Process according to claim 5 , wherein the at least one primary antioxidant is selected from the group consisting of a sterically hindered phenol and a sterically hindered amine.
19 . Process according to claim 5 , wherein the total amount of the at least one primary antioxidant B ranges from 0.03 wt.-% to 0.2 wt.-%, based on the total weight of the polypropylene resin.
20 . Process according to claim 5 , wherein the total amount of the at least one primary antioxidant B ranges from 0.03 wt.-% to 0.2 wt.-%, based on the total weight of the polypropylene resin.
21 . Process according to claim 7 , wherein the at least one acid scavenger is selected from the group consisting of a hydrotalcite, a metal stearate and a metal oxide.
22 . Process according to claim 7 , wherein the total amount of the at least one acid scavenger C ranges from 0.1 wt.-% to 0.2 wt.-%, based on the total weight of the polypropylene resin.
23 . Polypropylene resin as used in the process according to claim 1 , characterized by
A) at least one secondary antioxidant of formula (I) and/or formula (II), the secondary antioxidant being in combination with a further secondary antioxidant A1 selected from the group consisting of a phosphite, phosphonite and other phosphorous based antioxidant.
24 . Polypropylene resin as used in the process according to claim 11 , the polypropylene resin further comprising
B) at least one primary antioxidant, and
C) at least one acid scavenger.
25 . Polypropylene resin as used in the process according to claim 24 , wherein the at least one primary antioxidant is selected from the group consisting of a sterically hindered phenol and a sterically hindered amine, and wherein the at least one acid scavenger is selected from the group consisting of a hydrotalcite, a metal stearate and a metal oxide.
26 . Composition for use in a polypropylene resin according to claim 11 , the composition further comprising
B) at least one primary antioxidant, and
C) at least one acid scavenger.
27 . Composition for use in a polypropylene resin according to claim 26 , wherein the at least one secondary antioxidant of formula (I), the secondary antioxidant being in combination with a further secondary antioxidant A1 selected from the group consisting of a phosphite, phosphonite or other phosphorous based antioxidant, wherein the at least one primary antioxidant is selected from the group consisting of a sterically hindered phenol and a sterically hindered amine, and wherein the at least one acid scavenger is selected from the group consisting of a hydrotalcite, a metal stearate and a metal oxide.