Cross-linked polycarbonate resin with improved chemical and flame resistance

Patent metadata

Field	Value
Publication number	US-9303120-B2
Application number	US-201314137532-A
Country	US
Kind code	B2
Filing date	Dec 20, 2013
Priority date	Dec 20, 2012
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Processes for increasing the chemical resistance of a surface of a formed article are disclosed. The formed article is produced from a polymeric composition comprising a photoactive additive containing photoactive groups derived from a monofunctional benzophenone. The surface of the formed article is then exposed to ultraviolet light to cause crosslinking of the photoactive additive and produce a crosslinked surface. The crosslinking enhances the chemical resistance of the surface. Various means for controlling the depth of the crosslinking are also discussed.

First claim

The invention claimed is:

1. A method for preparing an article that has a high probability of passing a UL94 V1 test, comprising:
(a) designing a polymeric composition to be exposed to a designed dosage (D) of UV radiation, wherein the polymeric composition comprises:
(i) a cross-linkable polycarbonate resin having endcaps derived from 4-monohydroxybenzophenone and a weight average molecular weight of 15,000 to 30,000, and
(ii) optionally one or more polymeric base resins, and
wherein the polymeric composition has a designed weight percentage of the endcaps derived from 4-monohydroxybenzophenone (HBP), a designed melt flow rate (MF) and a designed weight average molecular weight (MW);

(b) preparing the cross-linkable polycarbonate resin by interfacial polymerization;
(c) optionally blending the cross-linkable polycarbonate resin with the optional one or more polymeric base resins to form the polymeric composition;
(d) forming an article from the polymeric composition; and
(e) exposing the formed article to the designed UV dosage;
wherein D, HBP, MF, and MW are selected based on an flame performance equation as follows:
Sqrt( p ( FTP )+0.01)=−0.37308+(0.05345× D )+(0.22797 ×HBP )−(2.06081×10 −6 × MW )−(0.092440× MF )+(2.81460×10 −6 × MW×MF )+(0.000583× D 2 )

wherein p(FTP) is the probability of a first time pass in a UL94 V1 test at 1.2 mm thickness after UV exposure and after 7 days of aging at 70° C.; p(FTP) is 0.7 or greater; D is at least 12 J/cm 2 of UVA radiation; and MF is from 7 to 20 g/10 min measured at 300° C./1.2 kg/360 sec dwell.

2. The method of claim 1 , wherein the UV radiation is filtered to provide at least 12 J/cm 2 of UVA radiation and no detectable UVC radiation, as measured using an EIT PowerPuck.

3. The method of claim 1 , wherein the UV radiation is unfiltered and provides at least 12 J/cm 2 of UVA radiation and and at least 0.45 J/cm 2 of UVC radiation, as measured using an EIT PowerPuck.

4. The method of claim 1 , wherein D, HBP, MF, and MW are also selected based on a percentage retention of tensile elongation equation as follows:
Sqrt( ER+ 1.04)=−29.23264+(0.62157× D )+(1.57655× HBP )+(1.27584×10 −3 × MW )−(1.63711×10 −5 ×D×MW )−(0.002382 × D 2 )

wherein ER is the percentage retention of tensile elongation after exposure to acetone at a thickness of 3.2 mm; wherein the UV radiation is provided by a UV light source that provides at least 12 J/cm 2 of UVA radiation and at least 0.45 J/cm 2 of UVC radiation as measured using an EIT PowerPuck; and ER is 85% or higher.

5. The method of claim 1 , wherein D and MF are also selected based on a Delta YI equation as follows:
Ln(Delta YI)=1.01074+(0.08387× D )−(0.041908× MF )−(0.00077× D 2 )+(2.41546×10 −3 × MF 2 )

wherein Delta YI is the change in YI after exposure to at least 12 J/cm 2 of UVA radiation and at least 0.45 J/cm 2 of UVC radiation at 3.2 mm thickness, measured before UV exposure and at least 48 hours after UV exposure; wherein the UV radiation is provided by a UV light source that provides at least 12 J/cm 2 of UVA radiation and at least 0.45 J/cm 2 of UVC radiation; and wherein the delta YI is 15 or less.

6. The method of claim 5 , wherein the delta YI is 10 or less.

7. The method of claim 5 , wherein the delta YI is 8 or less.

8. The method of claim 1 , wherein D, HBP, MF, and MW are also selected based on a percentage retention of tensile elongation equation as follows:
Sqrt( ER+ 1.04)=−30.25285+(0.62157× D )+(1.57655× HBP )+(1.27584×10 −3 ×MW)−(1.63711×10 −5 ×D×MW )−(0.002382 × D 2 )

wherein ER is the percentage retention of tensile elongation after exposure to acetone at a thickness of 3.2 mm; wherein the UV radiation is provided by a filtered UV light source that provides at least 12 J/cm 2 of UVA radiation and no detectable UVC radiation, as measured using an EIT PowerPuck; and ER is 85% or higher.

9. The method of claim 1 , wherein D and MF are also selected based on a Delta YI equation as follows:
Ln(Delta YI)=0.44154+(0.07712× D )−(0.041908× MF )−(0.00077× D 2 )+(2.41546×10 −3 ×MF 2 )

wherein Delta YI is the change in YI after exposure to at least 12 J/cm 2 of UVA radiation and no detectable UVC radiation at 3.2 mm thickness, measured before UV exposure and at least 48 hours after UV exposure; wherein the UV radiation is provided by a filtered UV light sourcethat provides at least 12 J/cm 2 of UVA radiation and no detectable UVC radiation, as measured using an EIT PowerPuck; and wherein the delta YI is 15 or less.

10. The method of claim 9 , wherein the delta YI is 10 or less.

11. The method of claim 9 , wherein the delta YI is 8 or less.

12. The method of claim 1 , wherein MW is from 15,000 to 30,000.

13. The method of claim 1 , wherein HBP is from 1.2 wt % to 4 wt %.

14. The method of claim 1 , wherein the polymeric composition comprises a polymeric base resin, and the polymeric base resin is a polycarbonate resin that does not contain photoactive groups.

15. The method of claim 14 , wherein the weight ratio of the cross-linkable polycarbonate resin to the polymeric base resin is from about 50:50 to about 85:15.

16. The polymeric composition prepared by the method of claim 1 .

17. A method for preparing an article that has a low delta YI after exposure to unfiltered UV radiation, comprising:
(a) designing a polymeric composition to be exposed to a designed dosage (D) of unfiltered UV radiation, wherein the polymeric composition comprises:
(i) a cross-linkable polycarbonate resin having endcaps derived from 4-monohydroxybenzophenone and a weight average molecular weight of 15,000 to 30,000, and
(ii) optionally one or more polymeric base resins, and
wherein the polymeric composition has a designed weight percentage of the endcaps derived from 4-monohydroxybenzophenone (HBP), a designed melt flow rate (MF) and a designed weight average molecular weight (MW);

(b) preparing the cross-linkable polycarbonate resin by interfacial polymerization;
(c) optionally blending the cross-linkable polycarbonate resin with the optional one or more polymeric base resins to form the polymeric composition;
(d) forming an article from the polymeric composition; and
(e) exposing the formed article to the designed UV dosage;
wherein D and MF are selected based on a Delta YI equation as follows:
Ln(Delta YI)=1.01074+(0.08387× D )−(0.041908× MF )−(0.00077× D 2 )+(2.41546×10 −3 × MF 2 )

wherein Delta YI is the change in YI after exposure to at least 12 J/cm 2 of UVA radiation and at least 0.45 J/cm 2 of UVC radiation at 3.2 mm thickness, measured before UV exposure and at least 48 hours after UV exposure; wherein the unfiltered UV radiation provides at least 12 J/cm 2 of UVA radiation and at least 0.45 J/cm 2 of UVC radiation; and wherein the delta YI is 15 or less.

18. The method of claim 17 , wherein D, HBP, MF, and MW are also selected based on a retention of tensile elongation equation as follows:
Sqrt( ER+ 1.04)=−29.23264+(0.62157× D )+(1.57655× HBP )+(1.27584×10 −3 × MW )−(1.63711×10 −5 ×D×MW )−(0.002382 × D 2 )

wherein ER is the percentage retention of tensile elongation after exposure to acetone at a thickness of 3.2 mm; and ER is 85 % or higher.

19. The method of claim 18 , wherein the delta YI is 10 or less.

20. The method of claim 18 , wherein the delta YI is 8 or less.

21. The method of claim 17 , wherein MF is from 7 to 20 g/10 min measured at 300° C./1.2 kg/360 sec dwe

Assignees

• Sabic Innovative Plastics Ip
• Sabic Global Technologies Bv

Inventors

• Sybert Paul Dean
• Flores Amanda
• Johnson Peter
• Morizur Jean-Francois
• Frazee Andrew
• Evans Thomas L

Classifications

• C08L69/00

  Compositions of polycarbonates; Compositions of derivatives of polycarbonates · CPC title

• C08K5/549

  containing silicon in a ring · CPC title

• C08G64/24

  and phenols · CPC title

• C08L2201/02

  Flame or fire retardant/resistant · CPC title

• C08K5/42

  Sulfonic acids; Derivatives thereof · CPC title