FLAME RETARDANT POLYCARBONATE COMPOSITIONS AND THIN-WALL ARTICLES MADE THEREFROM

Abstract

A flame retardant composition comprising: 34-94 wt % of a homopolycarbonate, acopolycarbonate, or a combination thereof; 5-85 wt % poly(carbonate-siloxane), in an amount effective to provide 2-6 wt % dimethyl siloxane; 0.05-0.6 w t%, preferably 0.2-0.4 wt%, of a C.sub.1-16 alkyl sulfonate salt flame retardant; 1-15 wt % of a mineral-filled silicone flame retardant synergist; 0.05-0.5 wt % of an anti-drip agent; wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %; and wherein a molded sample of the flame retardant composition has a Vicat softening temperature of greater than or equal to 140° C. as measured according to the ISO-306 standard at a load of 10 N and a heating rate of 50° C. per hour, and a flame test rating of V0 as measured according to UL-94 at a thickness of 1.0 millimeter, or at a thickness of 0.8 millimeter.

Claims

1. A flame retardant composition comprising: 34-94 wt % of a homopolycarbonate, a copolycarbonate, or a combination thereof; 5-85 wt % poly(carbonate-siloxane), in an amount effective to provide 2-6 wt % dimethyl siloxane; 0.05-0.6 wt % of a C.sub.1-16 alkyl sulfonate salt flame retardant; 1-15 wt % of a mineral-filled silicone flame retardant synergist; 0.05-0.5 wt % of an anti-drip agent; optionally, 0.001-10 wt % of an additive composition, or 0.1-20 wt % of a glass fiber composition, or a combination thereof wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %; and wherein a molded sample of the flame retardant composition has a Vicat softening temperature of greater than or equal to 140° C. as measured according to the ISO-306 standard at a load of 10 N and a heating rate of 50° C. per hour, and a flame test rating of V0 as measured according to UL-94 at a thickness of 1.0 millimeter, or at a thickness of 0.8 millimeter.

2. The flame retardant composition according to claim 1, wherein a molded sample of the flame retardant composition has a notched Izod impact resistance measured according to the ISO-180:2000 standard with a 5.5 joule hammer on a 4 millimeter specimen at −30° C. of greater than or equal to 35 kilojoules per square meter; a melt volume rate of greater than or equal to 5 centimeters cubed per 10 minutes at 300° C. using a 1.2-kilogram weight, in accordance with ASTM D1238-04; or a combination thereof.

3. The flame retardant composition of claim 1, wherein the homopolycarbonate or copolycarbonate comprises bisphenol A repeating units.

4. The flame retardant composition of claim 1, wherein the homopolycarbonate is present, and comprises a bisphenol A homopolycarbonate having a weight average molecular weight from 20,000 to 30,000 grams/mole; a bisphenol A homopolycarbonate having a weight average molecular weight from 25,000 to 35,000 grams/mole; or a combination thereof, each as measured via gel permeation chromatography using bisphenol A homopolycarbonate standards.

5. The flame retardant composition of claim 1, wherein the poly(carbonate-siloxane) comprises 5 to 99 weight percent of bisphenol A carbonate units and 1 to 50 weight percent of dimethylsiloxane units, each based on the weight of the polydimethylsiloxane.

6. The flame retardant composition of claim 1, wherein the silicone of the mineral-containing silicone flame retardant synergist is a polydiorganosiloxane.

7. The flame retardant composition of claim 1, wherein the C.sub.1-16 alkyl sulfonate salt flame retardant comprises potassium perfluorobutane sulfonate, potassium perfluoroctane sulfonate, tetraethyl ammonium perfluorohexane sulfonate, or a combination thereof.

8. The flame retardant composition of claim 1, wherein the mineral-filled silicone flame retardant synergist comprises 1-20 wt % silicon, or 2-18 wt % silicon, or 3-15 wt % silicone, or 5-12 wt % silicon, or 6-10 wt % silicon, or 7-8 wt % silicon; or wherein the mineral-filled silicone flame retardant synergist is a silicone flame retardant additive present in an amount of 1-99 wt %, or 1-75 wt %, or 1-50 wt %, or 1-25 wt %, or 1 to 20 wt % in combination with a mineral filler synergist present in an amount of 1-99 wt %, or 25-99 wt %, or 50-99 wt %, or 75-99 wt %, or 80-90 wt %, each based on the total weight of the combination.

9. The flame retardant composition of claim 1, wherein the anti-drip agent comprises a fluoropolymer.

10. The flame retardant composition of claim 1 comprising 65-75 wt % of a bisphenol homopolycarbonate a weight average molecular weight from 25,000 to 35,000 grams/mole; 15-70 wt % of the poly(carbonate-siloxane); 0.05-0.6 wt % of potassium perfluorobutane sulfonate as the C.sub.1-16 alkyl sulfonate salt flame retardant; 1-10 wt % of the mineral-filled poly(dimethylsiloxane) flame retardant synergist; 0.01-0.5 wt % anti-drip agent; optionally, 0.01-5 wt % of an additive composition, or 1-20 wt % of a glass fiber composition, or a combination thereof; wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %.

11. The flame retardant composition of claim 1, wherein the additive is present and the additive comprises a filler, a reinforcing agent, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet light stabilizer, a plasticizer, a lubricant, a mold release agent, an antistatic agent, a surface effect additive, a radiation stabilizer, a flame retardant different from the C.sub.1-16 alkyl sulfonate salt flame retardant and the mineral-filled poly(dimethylsiloxane) flame retardant synergist, or a combination thereof.

12. An article of claim 1, wherein the article is an extruded article, a molded article, pultruded article, a thermoformed article, a foamed article, a layer of a multi-layer article, a substrate for a coated article, or a substrate for a metallized article.

13. The article of claim 12, wherein the article is a molded housing.

14. The article of claim 12, wherein the article is an electrical circuit housing.

15. A method for forming the article of claim 12, comprising molding, casting, or extruding the article.

16. The flame retardant composition of claim 1, wherein the homopolycarbonate is present, and comprises a bisphenol A homopolycarbonate having a weight average molecular weight from 20,000 to 25,000 grams/mole; a bisphenol A homopolycarbonate having a weight average molecular weight from, preferably 27,000 to 32,000 grams/mole; or a combination thereof, each as measured via gel permeation chromatography using bisphenol A homopolycarbonate standards.

17. The flame retardant composition of claim 1, wherein the polydiorganosiloxane is a polydimethylsiloxane.

18. The flame retardant composition of claim 1, wherein the C.sub.1-16 alkyl sulfonate salt flame retardant comprises potassium perfluorobutane sulfonate.

19. The flame retardant composition of claim 1 comprising 65-75 wt % of a bisphenol homopolycarbonate a weight average molecular weight from 27,000 to 32,000 grams/mole; 15-70 wt % of the poly(carbonate-siloxane); 0.2-0.4 wt % of potassium perfluorobutane sulfonate as the C.sub.1-16 alkyl sulfonate salt flame retardant; 1-10 wt % of the mineral-filled poly(dimethylsiloxane) flame retardant synergist; 0.01-0.5 wt % anti-drip agent; optionally, 0.01-5 wt % of an additive composition, or 1-20 wt % of a glass fiber composition, or a combination thereof; wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %.

20. The article of claim 12, wherein the article is a molded article.

Description

EXAMPLES

[0067] The materials in Table 1 were used.

TABLE-US-00001 TABLE 1 Component Description (Trade name) Source PC-2 Linear poly (bisphenol A carbosate), Mw = 30,000-31,000 g/mol per SABIC GPC using bisphenol A homopoly carbonate standards PC-Si Polydimethylsiloxane)-bisphenol A polycarbonate SABIC copolymer, produced via interfacial polymerization, 20 wt % siloxane, average PDMS block length of 45 units (D45), Mw = 29,000 to 31,000 g/mol, as determined by GPC using bisphenol A homopolycarbonate standards, para- cumylphenol (PCP) end-capped, PDI = 2-3 Rimar Potassium perfluorobutane sulfonate 3M KSS Potassium diphenylsulfone sulfonate Sloss Industries AO Hindered phenolic antioxidant, available as Ciba IRGANOX 1076 PETS Pentaerythritol tetrastearate Faci TSAN Styrene-acrylonitrile (SAN)-encapsulated PTFE SABIC Stab Tris(2,4-di-tert-butylphenyl) phosphite, Ciba-Geigy available as IRGAFOS 168 Si-FR DynaSil ™ 1350N2 from Polymer Dynamix Dynamix MBS Methyl methacrylate-butadiene-styrene Dow Chemical

[0068] The samples were prepared as described below and the following test methods were used.

All powder additives were combined together with the polycarbonate powder(s), using a paint shaker, and fed through one feeder to an extruder. Extrusion for all combinations was performed on a 25 mm twin screw extruder according to the extrusion profile in Table 2.

TABLE-US-00002 TABLE 2 Parameters Unit Typical values Feed ° C.  40 Zone 1 Temp ° C. 200 Zone 2 Temp ° C. 250 Zone 3 Temp ° C. 270 Zone 4-9 Temp ° C. 310 Screw Speed rpm 300 Throughput kg/h ~14 Torque % Max.

[0069] Molding of specimens for testing was performed on an Engel 45 Ton injection molding machine equipped with insert molds from AXXICON. Temperature profiles and general molding parameters used for standard and abusive conditions are reported in Table 3.

TABLE-US-00003 TABLE 3 Parameters Unit Conditions Drying Temperature ° C. 120 Drying Time h  2 Hopper temperature ° C.  40 Nozzle Temperature ° C. 305 Rear-Zone 1 Temperature ° C. 290 Middle-Zone 2 Temperature ° C. 300 Front-Zone 3 Temperature ° C. 310 Residence time min  5

[0070] Melt volume rate (MVR) was determined at 300° C. using a 1.2-kilogram weight, over 300 seconds in accordance with ASTM D1238-04.

[0071] ISO notched Izod impact measurements (INI) were performed on notched 4 mm-thick ISO bars at -30° C., in accordance with the ISO-180:2000 standard with a 5.5 J hammer.

[0072] Vicat softening temperature (Vicat) was measured on 4 mm thick ISO bars in accordance with the ISO-306 standard at a load of 10 N and a heating rate of 50° C./hr (B50).

[0073] Flammability was determined by using the UL-94 standard (Table 4). Vx vertical flammability tests were performed at 1.0 mm and 0.8 mm. V-ratings were obtained for every set of 5 bars. In some cases, a second set of 5 bars was tested to give an indication of the robustness of the rating.

TABLE-US-00004 TABLE 4 t.sub.1 and/or t.sub.2 5-bar FOT* burning drips V0 <10  <50 no V1 <30 <250 no V2 <30 <250 yes N.R. (no rating) >30 >250 *FOT: total flame-out-time for all 5 bars (FOT = t1 + t2)

Examples 1-13

[0074] The formulations and properties of Example 1-13 are shown in Table 5.

TABLE-US-00005 TABLE 5 Unit 1* 2* 3* 4* 5* 6* 7 8* 9* 10* 11 12 13* PC-2 wt % 98.95 93.95 94.25 94.95 89.95 76.95 71.95 71.95 72.35 77.25 74.75 72.25 69.75 PC-Si wt % 22 22 22 22 22 22 22 22 Stab wt % 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 PETS wt % 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 MBS wt % 4 4 TSAN wt % 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Rimar wt % 0.4 0.4 0.1 0.4 0.4 0.4 0.4 0.1 0.1 0.1 0.1 KSS wt % 0.4 Si-FR wt % 5 5 5 5 5 5 2.5 5 7.5 Total wt % 100 100 100 100 100 100 100 100 100 100 100 100 100 Vicat ° C. 145.6 144.7 145.1 144.8 144.1 143.8 143.7 142.9 143.5 144.3 143.6 143.1 142.8 B/50 INI kj/m.sup.2 12.3 15.4 18.8 49.5 41.2 68.2 63.3 50.1 54.6 64.1 45.5 39.3 44.4 −30° C. MVR cm.sup.3/ 5.9 6.1 6.3 4.2 3.8 4.2 4.4 5.0 3.8 4.7 4.9 6.0 5.3 10 min UL94 V0 V1 NR NR NR V1 V0 V1 V0 V1 V0 V0 V1 1.0 mm FOT, s 12 36 115 170 192 79 39 68 37 42 30 26 66 1.0 mm UL94 V0 V1 NR NR NR V1 V0 V2 V2 NR V0 V0 NR 0.8 mm FOT, s 17 74 96 154 174 35 38 64 99 83 27 10 193 0.8 mm *Comparative examples

[0075] Comparative Example 1 shows that the absence of Si-FR and PC-Si resulted in a V0 UL94 rating at thicknesses of 1.0 mm and 0.8 mm and poor low temperature impact resistance. The addition of Si-FR to the flame retardant compositions wherein PC-Si was absent and Rimar loading was 0.4 wt % failed to improve the low-temperature impact resistance and adversely affected the flame test rating in improved impact resistance (compare Comparative Example 2 with Comparative Example 1). Reducing the Rimar loading from 0.4 wt % to 0.1 wt % resulted in both poor flame test rating at 1.0 mm and 0.8 mm thicknesses and poor low-temperature impact resistance (compare Comparative Example 3 with Comparative Example 2). Comparative Example 4 shows that incorporation of an impact modifier (i.e. MBS) in a composition wherein Si-FR and PC-Si are absent resulted in an improvement in the low-temperature impact resistance, but a deterioration of the flame test ratings (compare Comparative Example 4 with Comparative Example 3). The combination of Si—FR and MBS failed to improve the low-temperature impact resistance (compare Comparative Example 5 with Comparative Example 4). As shown in Example 7, the combination of PC—Si and Si—FR in a composition with 0.4 wt % Rimar salt loading resulted in a flame test rating of V0 at both the 1.0 mm and 0.8 mm thicknesses, as well as an improved low-temperature impact resistance (INI, −30 C>60 kJ/m.sup.2). Replacement of Rimar salt with KSS resulted in an adverse effect on the flame test ratings at both 1.0 mm and 0.8 mm thicknesses (compare Comparative Example 8 with Example 7). A composition having a combination of PC—Si and Si—FR and excluding Rimar salt and KSS flame retardants resulted in V0 at a thickness of 1.0 mm and V2 at a thickness of 0.8 mm (see Comparative Example 9). Comparative Example 10 shows that a composition having PC—Si, but not Si—FR at a lower loading of Rimar salt (i.e., 0.1 wt %) failed to provide improved flame test ratings at the 1.0 mm and 0.8 mm thicknesses (compare Comparative Example 10 with Comparative Example 6). However, the combination of PC—Si and Si—FR, even at the lower Rimar salt loading of 0.1 wt % resulted in the combination of V0 flame test ratings at both 1.0 mm and 0.8 mm thicknesses and good low-temperature impact resistance (Example 11). Example 12 shows that when the loading of Si-FR is increased from 2.5 wt % to 5 wt %, that the desired combination of V0 flame test ratings at both 1.0 mm and 0.8 mm thicknesses and good low-temperature impact resistance is obtained. Comparative Example 13 shows that in compositions having a combination of PC—Si (22 wt %) and Si—FR wherein Rimar salt is present at 0.1 wt % loading, that increasing the Si-FR loading from 5 wt % to 7.5 wt % resulted in a loss of V0 flame test ratings at both the 1.0 mm and 0.8 thicknesses. To summarize, the combination of PC—Si, Si—FR, and Rimar resulted in the desired combination of V0 flame test ratings at both 1.0 mm and 0.8 mm thicknesses and good low-temperature impact resistance (i.e., greater than 35 kJ/m.sup.2 at −30° C.).

[0076] The following aspects are illustrative of possible embodiments.

[0077] Aspect 1. A flame retardant composition comprising: 34-94 wt % of a homopolycarbonate, a copolycarbonate, or a combination thereof; 5-85 wt % poly(carbonate-siloxane), in an amount effective to provide 2-6 wt % dimethyl siloxane; 0.05-0.6 wt %, preferably 0.1-0.4 wt %, of a C.sub.1-16 alkyl sulfonate salt flame retardant; 1-15 wt % of a mineral-filled silicone flame retardant synergist; 0.05-0.5 wt % of an anti-drip agent; optionally, 0.001-10 wt % of an additive composition, or 0.1-20 wt % of a glass fiber composition, or a combination thereof, wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %; and wherein a molded sample of the flame retardant composition has a Vicat softening temperature of greater than or equal to 140° C. as measured according to the ISO-306 standard at a load of 10 N and a heating rate of 50° C. per hour, and a flame test rating of V0 as measured according to UL-94 at a thickness of 1.0 millimeter, or at a thickness of 0.8 millimeter.

[0078] Aspect 2. The flame retardant composition according to claim 1, wherein a molded sample of the flame retardant composition has a notched Izod impact resistance measured according to the ISO-180:2000 standard with a 5.5 joule hammer on a 4 millimeter specimen at −30° C. of greater than or equal to 35 kJ/m.sup.2; a melt volume rate of greater than or equal to 5 centimeters cubed per 10 minutes at 300° C. using a 1.2-kilogram weight, in accordance with ASTM D1238-04; or a combination thereof.

[0079] Aspect 3. The flame retardant composition of any one of the preceding claims, wherein the homopolycarbonate or copolycarbonate comprises bisphenol A repeating units.

[0080] Aspect 4. The flame retardant composition of any one of the preceding claims, wherein the homopolycarbonate is present, and comprises a bisphenol A homopolycarbonate having a weight average molecular weight from 20,000 to 30,000 grams/mole, preferably 20,000 to 25,000 grams/mole; a bisphenol A homopolycarbonate having a weight average molecular weight from 25,000 to 35,000 grams/mole, preferably 27,000 to 32,000 grams/mole; or a combination thereof, each as measured via gel permeation chromatography using bisphenol A homopolycarbonate standards.

[0081] Aspect 5. The flame retardant composition of any one of the preceding claims, wherein the poly(carbonate-siloxane) comprises 5 to 99 weight percent of bisphenol A carbonate units and 1 to 50 weight percent of dimethylsiloxane units, each based on the weight of the polydimethylsiloxane.

[0082] Aspect 6. The flame retardant composition of any one of the preceding claims, wherein the silicone of the mineral-containing silicone flame retardant synergist is a polydiorganosiloxane, preferably a polydimethylsiloxane.

[0083] Aspect 7. The flame retardant composition of any one of the preceding claims, wherein the C.sub.1-16 alkyl sulfonate salt flame retardant comprises potassium perfluorobutane sulfonate, potassium perfluoroctane sulfonate, tetraethylammonium perfluorohexane sulfonate, or a combination thereof, preferably potassium perfluorobutane sulfonate.

[0084] Aspect 8a. The flame retardant composition of any one of the preceding claims, wherein the mineral-filled silicone flame retardant synergist is a silicone flame retardant additive present in an amount of 1-99 wt %, or 1-75 wt %, or 1-50 wt %, or 1-25 wt %, or 1 to 20 wt % in combination with a mineral filler synergist present in an amount of 1-99 wt %, or 25-99 wt %, or 50-99 wt %, or 75-99 wt %, or 80-90 wt %, each based on the total weight of the combination.

[0085] Aspect 8b. The flame retardant composition of any one of the preceding claims, wherein the mineral-filled silicone flame retardant synergist comprises 1-20 wt % silicon, or 2-18 wt % silicon, or 3-15 wt % silicone, or 5-12 wt % silicon, or 6-10 wt % silicon, or 7-8 wt % silicon.

[0086] Aspect 9. The flame retardant composition of any one of the preceding claims, wherein the anti-drip agent comprises a fluoropolymer, preferably a polymer-encapsulated fluoropolymer, more preferably a polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer, or a combination thereof.

[0087] Aspect 10. The flame retardant composition of any one or more of the preceding claims comprising 65-75 wt % of a bisphenol homopolycarbonate a weight average molecular weight from 25,000 to 35,000 grams/mole, preferably 27,000 to 32,000 grams/mole; 15-70 wt % of the poly(carbonate-siloxane);0.2-0.6 wt %, preferably 0.2-0.4 wt % of potassium perfluorobutane sulfonate as the C.sub.1-16 alkyl sulfonate salt flame retardant; 1-10 wt % of the mineral-filled poly(dimethylsiloxane) flame retardant synergist; 0.01-0.5 wt % anti-drip agent; optionally, 0.01 to 5 wt % of an additive composition, or 0.1-10 wt % of a glass fiber composition, or a combination thereof wherein each amount is based on the total weight of the flame retardant composition, which sums to 100 wt %.

[0088] Aspect 11. The flame retardant composition of any one of the preceding claims, wherein the additive is present and the additive comprises a particulate filler, reinforcing agent (e.g, glass fibers), antioxidant, heat stabilizer, light stabilizer, ultraviolet light stabilizer, plasticizer, lubricant, mold release agent, antistatic agent, surface effect additive, radiation stabilizer, a flame retardant different from the C.sub.1-16 alkyl sulfonate salt flame retardant and the mineral-filled poly(dimethylsiloxane) flame retardant synergist, or a combination thereof

[0089] Aspect 12. An article of any one of the preceding claims, wherein the article is an extruded article, a molded article, pultruded article, a thermoformed article, a foamed article, a layer of a multi-layer article, a substrate for a coated article, or a substrate for a metallized article, preferably wherein the article is a molded article.

[0090] Aspect 13. The article of claim 12, wherein the article is a molded housing.

[0091] Aspect 14. The article of claim 12 or 13, wherein the article is an electrical circuit housing.

[0092] Aspect 15. A method for forming the article of any one or more of the preceding claims, comprising molding, casting, or extruding the article.

[0093] The compositions, methods, and articles may alternatively comprise, consist of, or consist essentially of, any appropriate materials, steps, or components herein disclosed. The compositions, methods, and articles may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any materials (or species), steps, or components, that are otherwise not necessary to the achievement of the function or objectives of the compositions, methods, and articles.

[0094] All ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt %, or, more specifically, 5 wt % to 20 wt %”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt % to 25 wt %,” etc.). “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “some aspects,” “an aspect,” and so forth, means that a particular element described in connection with the aspect is included in at least one aspect described herein, and may or may not be present in other aspects. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various aspects. A “combination thereof” is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

[0095] Unless specified to the contrary herein, all test standards are the most recent standard in effect as of the filing date of this application, or, if priority is claimed, the filing date of the earliest priority application in which the test standard appears.

[0096] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0097] Compounds are described using standard nomenclature. For example, any position not substituted by any indicated group is understood to have its valency filled by a bond as indicated, or a hydrogen atom. A dash (“-”) that is not between two letters or symbols is used to indicate a point of attachment for a substituent. For example, -CHO is attached through carbon of the carbonyl group.

[0098] The term “alkyl” means a branched or straight chain, unsaturated aliphatic hydrocarbon group, e.g., methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, t-butyl, n-pentyl, s-pentyl, and n- and s-hexyl. “Alkenyl” means a straight or branched chain, monovalent hydrocarbon group having at least one carbon-carbon double bond (e.g., ethenyl (—HC═CH.sub.2)). “Alkoxy” means an alkyl group that is linked via an oxygen (i.e., alkyl-O—), for example methoxy, ethoxy, and sec-butyloxy groups. “Alkylene” means a straight or branched chain, saturated, divalent aliphatic hydrocarbon group (e.g., methylene (—CH.sub.2—) or, propylene (—(CH.sub.2).sub.3-)). “Cycloalkylene” means a divalent cyclic alkylene group, wherein x is the number of hydrogens replaced by cyclization(s). “Cycloalkenyl” means a monovalent group having one or more rings and one or more carbon-carbon double bonds in the ring, wherein all ring members are carbon (e.g., cyclopentyl and cyclohexyl). “Aryl” means an aromatic hydrocarbon group containing the specified number of carbon atoms, such as phenyl, tropone, indanyl, or naphthyl. “Arylene” means a divalent aryl group. “Alkylarylene” means an arylene group substituted with an alkyl group. “Arylalkylene” means an alkylene group substituted with an aryl group (e.g., benzyl). The prefix “halo” means a group or compound including one more of a fluoro, chloro, bromo, or iodo substituent. A combination of different halo groups (e.g., bromo and fluoro), or only chloro groups may be present. The prefix “hetero” means that the compound or group includes at least one ring member that is a heteroatom (e.g., 1, 2, or 3 heteroatom(s)), wherein the heteroatom(s) is each independently N, O, S, Si, or P. “Substituted” means that the compound or group is substituted with at least one (e.g., 1, 2, 3, or 4) substituents that may each independently be a C.sub.1-9 alkoxy, a C.sub.1-9 haloalkoxy, a nitro (—NO.sub.2), a cyano (—CN), a C.sub.1-6 alkyl sulfonyl (—S(═O).sub.2-alkyl), a C.sub.6-12 aryl sulfonyl (—S(═O).sub.2-aryl)a thiol (—SH), a thiocyano (—SCN), a tosyl (CH.sub.3C.sub.6H.sub.4SO.sub.2—), a C.sub.3-12 cycloalkyl, a C.sub.2-12 alkenyl, a C.sub.5-12 cycloalkenyl, a C.sub.6-12 aryl, a C.sub.7-13 arylalkylene, a C.sub.4-12 heterocycloalkyl, and a C.sub.3-12 heteroaryl instead of hydrogen, provided that the substituted atom's normal valence is not exceeded. The number of carbon atoms indicated in a group is exclusive of any substituents. For example —CH.sub.2CH.sub.2CN is a C.sub.2 alkyl group substituted with a nitrile.

[0099] While particular aspects have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.