Processes for designing cross-linkable polycarbonates and articles formed therefrom

1. A process for preparing an article that has a high probability of passing UL94 V0 test, the process comprising:

(A) providing a polymeric composition to be exposed to a dosage (D) of UVA radiation, wherein the polymeric composition comprises:

(i) a cross-linkable polycarbonate resin including repeating units derived from a dihydroxybenzophenone;

(ii) a flame retardant; and

(iii) optionally one or more polymeric base resins;

(iv) wherein the cross-linkable polycarbonate resin contains a molar percentage of the dihydroxybenzophenone (MOL %); and

(v) wherein the polymeric composition has:

(a) a molecular weight increase of polymeric components therein after exposure to UV radiation (MW_I in gram/mol)

(b) a melt flow rate (MF), MF being measured in cubic centimeter per 10 minutes according to ASTM D1238-13, 1.2 kg load, 300° C. temperature, 360 second dwell, and

(c) a weight percentage of the cross-linkable polycarbonate resin (WP);

(B) forming an article from the polymeric composition; and

(C) exposing the formed article to the dosage;

wherein D, MOL %, MW_I, MF, and WP are determined based on a flame performance equation as follows:

Sqrt(V0_Avg)=−0.62315+(9.21942×10 −3 ×WP)+(0.041498×D)+(4.34876×10 −5 ×MW_I)+(6.55546×10 −3 ×MOL %)+(0.089017×MF)+(9.87122×10 −4 ×WP×D)−(4.36994×10 −6 ×WP×MW_I)−(2.43440×10 −3 ×WP×MOL %)+(2.08870×10 −3 ×WP×MF)−(4.40362×10 −6 ×D×MW_I)−(2.32567×10 −3 ×D×MOL %)−(3.75290×10 −3 ×D×MF)+(2.05611×10 −5 ×MW_I×MF)+(5.61409×10 −3 ×MOL %×MF)+(2.98567×10 −9 ×(MW_I) 2 )+(6.17229×10 −3 ×(MOL %) 2 )−(0.017115×(MF) 2 )

wherein the article has an average V0(V0_Avg) that is the average of:

(i) the probability of a first time pass in a UL94 V0 test at a thickness of 1.2 mm after UV exposure measured after 2 days of aging at room temperature, and

(ii) the probability of a first time pass in a UL94 V0 test at a thickness of 1.2 mm after UV exposure measured after 7 days of aging at 70° C.; and

wherein V0 _Avg is at least 0.7; and

wherein D is measured in J/cm 2 of UVA radiation.

2. The process of claim 1 , wherein (a) D, MOL %, MW_I, WP, and MF are also determined based on a percentage retention of tensile elongation equation as follows:

Sqrt(% RE)=+1.37235+(0.077638×WP)+(0.67685×D)−(2.39234×10 31 3 ×MW_I)−(0.23516×MOL %)−(0.57165×MF)−(9.18615×10 −3 ×WP×MF)+(6.66016×10 −5 ×D×MW_I)−(0.019526×D×MOL %)+(2.07809×10 −4 ×MW_I×MOL %)+(2.79873×10 −7 ×(MW_I) 2 )+(0.056758×(MF) 2 )

wherein % RE is the percentage retention of tensile elongation after exposure to acetone at a thickness of 3.2 mm, measured according to ASTM D638-10 Type I method at 50 mm/min; and % RE is at least 85; or

(b) wherein D, MOL %, and MW_I are also determined based on a Delta YI equation as follows:

Ln(D_YI)=−0.047177+(0.062393×D+1.81716×10 −4 ×MW_I)+(0.017370×MOL %)−(5.48288×10 −6 ×D×MW_I)

wherein D_YI is the change in YI after exposure to the dosage D, measured before UVA exposure and at least 48 hours after UVA exposure according to ASTM E313-73 (D1925); and D_YI is 6 or less; or

(c) wherein D, MOL %, MW_I, and MF are also determined based on a Delta % T equation as follows:

(D_% T+8.90) 2.65 =+343.92310−(6.75832×D)−(0.022788−MW_I)+(0.43933×MOL %)−(3.84042×MF)+(5.56692× 10 −4 ×D×MW_I)−(8.77565 ×10 −4 ×MW_I×MOL %)+(8.94844×10 −4 ×MW_I×MF)

wherein D_% T is the change in light transmission after exposure to the dosage D, measured before UVA exposure and at least 48 hours after UVA exposure according to ASTM E313-73 (D1925); and D_% T is 3.5 or less; or

(d) wherein D, MOL %, MW_I, MF, and WP are also determined based on a gel thickness equation as follows:

Sqrt(GEL)=+2.69872−(0.093035×WP)+(0.31583×D)−(5.37830×10 −4 ×MW_I)+(0.28207×MOL %)−(0.092447×MF)−(2.29409×10 − 3 ×WP×D)+(2.03257×10 31 5 ×WP ×MW_I)+(0.010073×WP×MOL %)−(1.01623×10 −7 ×(MW_I) 2 )−(0.043959×(MOL %) 2 )

wherein GEL is a gel thickness on a surface of the article, measured in microns, and is at least 5.

3. The process of claim 1 , wherein the polymeric composition comprises the one or more polymeric base resins.

4. The process of claim 1 , wherein MOL % is from 2.5 to 20; or wherein MW_I is from about 600 to about 11,000; or wherein MF is from about 5 to about 20; or wherein WP is from 50 to 100.

5. The process of claim 1 , wherein the cross-linkable polycarbonate resin is a copolymer or a terpolymer.