Polycarbonate composition with thin-wall flame retardancy and high impact strength

Abstract

A thermoplastic composition includes (a) from 40 to 85 wt.% of a polycarbonate, (b) from 10 to 50 wt.% of a silicone-block-polycarbonate, (c) from 2 to 15 wt.% of a phosphorus flame retardant, and (d) from 1.0 to 10 wt.% of a flame-retardant synergist. The flame-retardant synergist may include clay, silicate, mica, talc, or combinations thereof. The thermoplastic composition has good flame retardancy such as V-0 rating at 1.6 mm thickness and V-1 rating at 1.5 mm thickness under UL94 standard, and good impact strength such as notched Izod impact strength of 100 J / m or more under ASTM D256.

Description

POLYCARBONATE COMPOSITION WITH THIN-WALL FLAME RETARD ANCY AND HIGH IMPACT STRENGTHCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and all benefit of U.S. Provisional Application No. 63 / 735,881, filed December 18, 2024, the entire disclosure of which is fully incorporated herein by reference.FIELD

[0002] This disclosure relates to flame retardant polycarbonate compositions, methods of manufacture thereof and articles comprising the same.BACKGROUND

[0003] Polycarbonate (PC) possesses high impact strength and toughness, heat resistance, and excellent transparency and mechanical properties. Polycarbonate also exhibits some flame retardance properties. However, dripping of particles occur when polycarbonates are exposed to flame, and the dripping worsens as wall thickness of the polycarbonate material decreases. Generally, unfilled polycarbonates may achieve a thin-wall flame retardancy of V-0 at 3.0 mm thickness under the UL94 standard, even without anti-dripping agent. When the thickness is reduced to 1.5 mm or 0.8 mm, polycarbonates without anti-dripping agent generally cannot achieve V-0 classification, as severe dripping occurs.

[0004] Polytetrafluoroethylene (PTFE) is conventionally used as an anti-dripping agent in polycarbonates. However, the decomposition of PTFE, tetrafluoroethylene monomer, and solvents used in PTFE synthesis generates perfluoroalkyl and polyfluoroalkyl substances (PF AS), which are potentially harmful to the environment. PF AS are known to accumulate in living organisms and cause toxic effect including impairing reproduction and fetal development.

[0005] Chinese Patent Application Publication No. 117327382 discloses a PC composition with good thin-wall flame retardancy and impact strength. However, the PC composition includes silicon nanotubes as an anti-dripping agent, which are costly nano materials and are difficult to disperse. Chinese Patent Application Publication No. 117511167 discloses a PC composition with good toughness and transparency, but requires at least 1.5 mm of thickness in order to achieve a thin-wall flame retardancy of V-0, and thus does not meet the thin-wall flame retardancy requirements in many applications.

[0006] Accordingly, there is a need for PFAS-free polycarbonate compositions having good thin-wall flame retardancy and impact strength.SUMMARY

[0007] The following is a brief summary of subj ect matter that is described in greater detail herein. This summary is not intended to be limiting as to the scope of the claims.

[0008] According to a first aspect of the present disclosure, a thermoplastic composition comprises (a) from 40 to 85 wt.% of a polycarbonate, (b) from 10 to 50 wt.% of a silicone-block- polycarbonate, (c) from 2 to 15 wt.% of a phosphorus flame retardant, (d) from 1.0 to 10 wt.% of a flame-retardant synergist.

[0009] The polycarbonate may comprise, for example, prime (or virgin) polycarbonate, post-consumer recycled (PCR) polycarbonate, branched polycarbonate, or combinations thereof. The phosphorus flame retardant may comprise, for example, phenoxyphosphazene, bisphenol A- bis(diphenyl phosphate) (BPADP), resorcinol bis(diphenyl phosphate) (RDP), 1,4-phenylene tetraphenyl ester (PX-220), polyphosphonates, 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10- oxide (DOPO), DOPO derivatives, or combinations thereof. The flame-retardant synergist may comprise an inorganic mineral such as clay, silicate, mica, talc, or combinations thereof. The thermoplastic composition may be free of perfluoroalkyl and polyfluoroalkyl substances (PF AS).

[0010] The thermoplastic composition may have a good flame retardancy such as, for example, at least V-0 at 1.6 mm thickness, at least V-l at 1.5 mm thickness, and at least V-l at 0.8 mm thickness, under UL94. The thermoplastic composition may also have good mechanical properties such as a notched Izod impact strength of 100 J / m or more under ASTM D256.

[0011] According to other aspects of the present disclosure, a thermoplastic pellet comprises the thermoplastic composition described above.

[0012] Yet further aspects of the present disclosure are directed to a method for producing a thermoplastic pellet comprises blending a thermoplastic masterbatch comprising the inventive thermoplastic composition provided herein, extruding the thermoplastic masterbatch through an extruder, and cutting the extruded thermoplastic masterbatch into pellets with a pelletizer.

[0013] Yet further aspects of the present disclosure are directed to a thermoplastic article comprising the inventive thermoplastic composition. The thermoplastic article can also be made from the thermoplastic pellet. The thermoplastic article may be body panels of electronic devices such as VR headsets, True Wireless Stereo (TWS), mobile phones, notebook personal computers, e-books, and tablet personal computers.DETAILED DESCRIPTION

[0014] Disclosed herein are thermoplastic compositions comprising (a) polycarbonate, (b) silicone-block-polycarbonate, (c) a phosphorus flame retardant, and (d) a flame-retardantsynergist. Also disclosed herein are thermoplastic pellets and articles produced from the thermoplastic compositions.

[0015] The terminology as set forth herein is for description of the various aspects only and should not be construed as limiting the disclosure as a whole. All references to singular characteristics or limitations of the present disclosure shall include the corresponding plural characteristic or limitation, and vice versa, unless otherwise specified or clearly implied to the contrary by the context in which the reference is made. Unless specified otherwise, “a,” “an,” “the,” and “at least one” are used interchangeably. Furthermore, as used in the description and the appended claims, the singular forms “a,” “an,” and “the” are inclusive of their plural forms, unless the context clearly indicates otherwise.

[0016] Unless otherwise expressly defined, all technical and scientific terms used herein have the same meaning as commonly understood by a person of ordinary skill in the art.

[0017] As used herein, the term “compounding” (including related terms, such as “compounded”) refers to the formation of a composition or mixture via melt mixing a neat polymer resin and at least one other ingredient including, but not limited to, one or more additives, or one or more other polymer resins, or both.

[0018] As used herein, the term “thermoplastic” refers to a polymer that softens when exposed to heat and returns to its original condition when at room temperature.

[0019] Unless otherwise expressly stated, it not intended that any method disclosed herein be construed as requiring that its steps be performed in a specific order, nor that any article set forth herein be construed as requiring specific orders or orientations to its individual components.

[0020] To the extent that the term “includes” or “including” is used in the description or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. Thus, use of the term “or” herein is the inclusive, and not the exclusive use.

[0021] Any composition described in the present disclosure can comprise, consist of, or consist essentially of the essential elements of the disclosure as described herein, as well as any additional or optional element described herein, or which is otherwise useful in plastic applications.

[0022] All percentages, parts, and ratios as used herein are by weight of the total blend on an “dry” basis, i.e., without solvents, unless otherwise specified.

[0023] All ranges and parameters, including but not limited to percentages, parts, and ratios, disclosed herein are understood to encompass any and all sub-ranges assumed and subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges beginning with a minimum value of 1 or more and ending with a maximum value of 10 or less (e.g., 1 to 6.1, or 2.3 to 9.4), and to each integer (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10) contained within the range. Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0024] The term “wt.%” or “weight percent,” as described herein, refers to the weight fraction of the individual component based on a total weight of the thermoplastic elastomer composition, unless otherwise noted.

[0025] Additionally, as used herein, the term “exemplary” is intended to mean serving as an illustration or example of something, and is not intended to indicate a preference.

[0026] As introduced above, the invention is directed to a thermoplastic composition comprising (a) polycarbonate, (b) silicone-block-polycarbonate, (c) a phosphorus flame retardant, and (d) a flame-retardant synergist. The thermoplastic composition may have flame retardant properties and mechanical properties as described below in greater detail.Polycarbonate

[0027] The polycarbonate of the thermoplastic composition may be a homopolymer made from same monomers or a copolymer of different monomers linked by carbonate or ester groups. The polycarbonate may be a linear polymer, a branched polymer, or a combination of linear and branched polycarbonates. Any polycarbonate is a candidate for use in the thermoplastic composition, whether obtained from petrochemical or bio-derived sources, and whether virginal or recycled, including prime (virgin) polycarbonate and post-consumer recycled (PCR) polycarbonate.

[0028] As used herein, the term “polycarbonate” means a composition having repeating structural carbonate units of formula (1):In formula (1), the R1groups in the repeating units may contain aromatic groups, aromatic organic groups, aliphatic groups, alicyclic groups, or combinations thereof. In any of the aspects provided herein, at least 60 percent of the total number of R1groups may contain aromatic organic groups with the balance thereof being aromatic, aliphatic, or alicyclic groups.

[0029] For example, each R1in the carbonate units of formula (1) may be a C6-C36 aromatic group in which at least one moiety is aromatic. Each R1may be an aromatic organic group, for example, a group of formula (2):- A1- Y1- A2- (2)In formula (2), each of the A1and A2may be a monocyclic divalent aryl group and Y1may be a bridging group having one or two atoms that separate A1and A2. For example, Y1may be selected from groups including -O-, -S-, -S(O) -, -S(O)2- -C(O)-, methylene, cyclohexyl-methylene, 2-[2.2.1]-bicycloheptylidene, ethylidene, isopropylidene, neopentylidene, cyclohexylidene, cyclopentadecyclidene, cyclododecylidene, and adamantylidene. The bridging group Y1may be a saturated or unsaturated hydrocarbon group such as methylene, cyclohexlylidene, or isopropylidene.

[0030] The polycarbonate may be endcapped by, for example, para-cumyl phenol, phenol, t-butyl phenol, octylphenol, or other end-capping groups compatible with polycarbonates. The polycarbonate may be synthesized by various methods including melt transesterification and phosgeneration method. The molecular weight of the polycarbonate is not particularly limited and may be, for example, a weight average molecular weight of 1,000 to 100,000 Daltons.

[0031] Exemplary polycarbonates include the homopolymer and copolymers having the structures below:

[0032] Exemplary polycarbonates include those disclosed in, for example, U.S. Pat. No. 8,841,367 and U.S. Pat. No. 10,100,192, each being incorporated by reference herein. Exemplary commercially available polycarbonates include, for example, Covestro APEC, SABIC XHT, SABIC EXL, SABIC PPC, SABIC SLX, and SABIC HFD.

[0033] The polycarbonate may be present in the thermoplastic composition in an amount of 40 wt.% to 85 wt.% based upon the total weight of the composition. For example, the polycarbonate may be present in the thermoplastic composition in an amount of 40 wt.% to 80 wt.%, 45 wt.% to 75 wt.%, 48 wt.% to 70 wt.%, 50 wt.% to 65 wt.%, 55 wt.% to 60 wt.%, or 60 wt.% to 65 wt.%, including all subranges and endpoints therebetween.Silicone-block-polycarbonate

[0034] The silicone-block-polycarbonate of the thermoplastic composition may also be referred to as a silicone-polycarbonate copolymer or polysiloxane-polycarbonate. The polycarbonate block of the silicone-block-polycarbonate may be any of the polycarbonates described above. In any of the aspects provided herein, the silicone-block-polycarbonate may be present in the thermoplastic composition in an amount of 5 wt.% to 50 wt.% based upon the total weight of the composition. For example, the silicone-block-polycarbonate may be present in the thermoplastic composition in an amount of 10 wt.% to 47 wt.%, 10 wt.% to 45 wt.%, 10 wt.% to 30 wt.%, 15 wt.% to 45 wt.%, 15 wt.% to 35 wt.%, 20 wt.% to 45 wt.%, 20 wt.% to 35 wt.%, or 30 wt.% to 35 wt.%, including all subranges and endpoints therebetween.

[0035] In the silicone-block-polycarbonate, the silicone content is greater than 0 wt.% to 50 wt.%, based on the total weight of the silicone-block-polycarbonate, including 1 wt.% to 45 wt.%, 2 wt.% to 40 wt.%, 3 wt.% to 35 wt.%, 5 wt.% to 30 wt.%, 8 wt.% to 25 wt.%, and 10 wt.% to 20 wt.%, including all subranges and endpoints therebetween. The silicone-block- polycarbonate may include any amount of the silicone block such as, for example, 1 wt.% to 99 wt.% based on the total weight of the silicone-block-polycarbonate, including 4 wt.% to 90 wt.%, 6 wt.% to 70 wt.%, 10 wt.% to 50 wt.%, and 20 wt.% to 40 wt.%, including all subranges and endpoints therebetween.

[0036] The silicone-block-polycarbonate may have a weight average molecular weight of 2,000 to 100,000 Daltons, including 5,000 to 50,000 Daltons, as measured by gel permeation chromatography using a crosslinked styrene-divinyl benzene column, at a sample concentration of 1 milligram per milliliter and as calibrated with polycarbonate standards. The silicone-block- polycarbonate may have a melt flow rate, as measured at 300°C / 1.2 kg, of 1 to 50 gram per 10 minutes (g / 10 min), including, for example, 2 to 30 g / 10 min, 5 to 20 g / 10 min, and 10 to 18 g / 10 min. Mixtures of silicone-block-polycarbonates of different flow properties may be used to achieve the overall desired flow property.

[0037] The silicone (also referred to as polysiloxane or polydiorganosiloxane) blocks of the copolymer comprise repeating diorganosiloxane units as in formula (3):In formula (3), each R is independently a C1-13 monovalent organic group. For example, each R can independently be a C1-C13 alkyl, C1-C13 alkoxy, C2-C13 alkenyl, C2-C13 alkenyloxy, C3- Ce cycloalkyl, C3-C6 cycloalkoxy, Ce-Cw aryl, Ce-Cio aryloxy, C7-C13 arylalkyl, C7-C13 aralkoxy, C7-C13 alkylaryl, or C7-C13 alkylaryloxy group. The foregoing groups can be fully or partially halogenated with fluorine, chlorine, bromine, or iodine, or a combination thereof. Combinations of the foregoing R groups can be used in the same copolymer.

[0038] The value of E in formula (3) can vary widely depending on the type and relative amount of each component in the thermoplastic composition, the desired properties of the composition, and like considerations. In any of the aspects provided herein, E may have an average value of 2 to 1,000, including 3 to 500 and 5 to 100. For example, E may have an average value of 10 to 75 or 40 to 60. Where E is of a lower value, e.g., less than 40, the thermoplastic composition may include a relatively large amount of the silicone-block-polycarbonate, e.g., 30 wt.% or more. Conversely, where E is of a higher value, e.g., 40 or more, the thermoplastic composition may include a relatively small amount of the silicone-block-polycarbonate, e.g., 15 wt.% or less.

[0039] A combination of a first and a second (or more) silicone-block-polycarbonate can be used, where the average value of E of the first copolymer is less than the average value of E of the second copolymer.

[0040] The silicone blocks may be of formula (4):In formula (4), E is as defined above; each R can be the same or different, and is as defined above; and each Ar can be the same or different, and is a substituted or unsubstituted Ce-Cso arylene group, where the bonds are directly connected to an aromatic moiety. The Ar groups in formula (4) can be derived from a C6-C30 dihydroxyarylene compound, for example a dihydroxyarylene compound. Exemplary dihydroxyarylene compounds include l,l-bis(4-hydroxyphenyl) methane, l,l-bis(4-hydroxyphenyl) ethane, 2,2-bis(4-hydroxyphenyl) propane, 2,2-bis(4-hydroxyphenyl) butane, 2,2-bis(4-hydroxyphenyl) octane, l,l-bis(4-hydroxyphenyl) propane, l,l-bis(4- hydroxyphenyl) n-butane, 2,2-bis(4-hydroxy-l -methylphenyl) propane, l,l-bis(4-hydroxyphenyl) cyclohexane, bis(4-hydroxyphenyl sulfide), and l,l-bis(4-hydroxy-t-butylphenyl) propane. Combinations comprising at least one of the foregoing dihydroxy compounds can also be used.

[0041] The silicone blocks may be of formula (5):In formula (5), R and E are as described above, and each R5is independently a divalent Ci- C30 organic group. The polymerized silicone unit may be the reaction residue of its corresponding dihydroxy compound. For example, the silicone blocks may be of formula (6):In formula (6), R and E are as defined above. R6is a divalent C2-C8 aliphatic group. Each M can be the same or different, and can be a halogen, cyano, nitro, Ci-Cs alkylthio, Ci-Cs alkyl, Ci- Cs alkoxy, C2-C8 alkenyl, C2-C8 alkenyloxy, C3-C8 cycloalkyl, C3-C8 cycloalkoxy, Ce-Cio aryl, Ce-Cio aryloxy, C7-C12 aralkyl, C7-C12 aralkoxy, C7-C12 alkylaryl, or C7-C12 alkylaryloxy group, where each n is independently 0, 1, 2, 3, or 4.

[0042] For example, M may be bromo or chloro, an alkyl group such as methyl, ethyl, or propyl, an alkoxy group such as methoxy, ethoxy, or propoxy, or an aryl group such as phenyl, chlorophenyl, or tolyl; R6may be a dimethylene, trimethylene, or tetramethylene group; and R may be a C1-8 alkyl, haloalkyl such as trifluoropropyl, cyanoalkyl, or aryl such as phenyl, chlorophenyl, or tolyl. R may be methyl, or a combination of methyl and trifluoropropyl, or a combination of methyl and phenyl. M may be methoxy, n may be 1, R2may be a divalent Ci- C3 aliphatic group, and R may be methyl.

[0043] The silicone blocks of formula (5) can be derived from the corresponding dihydroxy poly siloxane represented by formula (7):In formula (7), R, E, M, R6, and n are as defined above. Such dihydroxy polysiloxanes can be made from a platinum-catalyzed addition between an aliphatically unsaturated monohydric phenol and a siloxane hydride of formula (8):In formula (8), R and E are as previously defined. Exemplary aliphatically unsaturated monohydric phenols include eugenol, 2-alkylphenol, 4-allyl-2-methylphenol, 4-allyl-2- phenylphenol, 4-allyl-2-bromophenol, 4-allyl-2-t-butoxyphenol, 4-phenyl-2-phenylphenol, 2- methyl-4-propylphenol, 2-allyl-4,6-dimethylphenol, 2-allyl-4-bromo-6-methylphenol, 2-allyl-6- methoxy-4-methylphenol, and 2-allyl-4,6-dimethylphenol. Combinations comprising at least one of the foregoing can also be used.

[0044] The silicone-block-polycarbonate may comprise 50 to 99 weight percent of carbonate units and 1 to 50 weight percent of silicone units. For example, the silicone-block- polycarbonate may comprise carbonate units in an amount of 70 to 98 weight percent, including 75 to 97 weight percent, and silicone units in an amount of 2 to 30 weight percent, including 3 to 25 weight percent. The silicone-block-polycarbonate may be endcapped with para-cumyl phenol, phenol, t-butyl phenol, octylphenol, or other end-capping groups compatible with polycarbonates or silicones.

[0045] An exemplary silicone-block-polycarbonate is a block copolymer having the structure of formula (9) below:In formula (9), the silicone blocks are endcapped with eugenol, where x is 1 to 100, including 5 to 85, 10 to 70, 15 to 65, and 40 to 60. y may be 1 to 90 and z may be 1 to 600. For example, x maybe 30 to 50, y may be 10 to 30, and z may be 450 to 600. The silicone block may be randomly distributed or controlled distributed amongst the polycarbonate blocks.

[0046] Exemplary silicone-block-polycarbonates include those disclosed in, for example, U.S. Pat. No. 8,841,367 and PCT Publication No. WO 2013 / 100494, each being incorporated by reference herein.Phosphorus Flame Retardant

[0047] The thermoplastic composition further includes a phosphorous flame retardant. The phosphorus flame retardant of the thermoplastic composition may include, for example, phenoxyphosphazene, polyphosphazene, bisphenol A-bis(diphenyl phosphate) (BPADP), resorcinol bis(diphenyl phosphate) (RDP), 1,4-phenylene tetraphenyl ester (PX-220), polyphosphonate, 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), DOPO derivatives or combinations thereof. The phosphorus flame retardant may be present in the thermoplastic composition in an amount of 1 wt.% to 20 wt.% based upon the total weight of the thermoplastic composition. For example, the phosphorus flame retardant may be present in the thermoplastic composition in an amount of 2 wt.% to 15 wt.%, 2 wt.% to 10 wt.%, 3 wt.% to 8 wt.%, 3 wt.% to 6 wt.%, or 3 wt.% to 5 wt.%, including all subranges and endpoints therebetween.

[0048] The phenoxyphosphazene may comprise a cyclic phenoxyphosphazene represented by formula (10), a chainlike phenoxyphosphazene represented by the formula (11), a crosslinked phenoxyphosphazene compound obtained by crosslinking at least one species of phenoxyphosphazene represented by the formula (10) or (11) with a crosslinking group represented by formula (12).In formula (10) representing cyclic phenoxyphosphazene, m is an integer of 3 to 25, including an integer of 3 to 8, Ri and R2 can be the same or different and are independently a hydrogen, a halogen, a hydroxyl, a C6-30 aryl, a C1-12 allyl, a C1-12 alkoxy, or a C1-12 alkyl group.In formula (11) representing chainlike phenoxyphosphazene, Xi is — N=P(0RI)3 or — N= P(O)ORi, Yi is — P(ORi)4 or — P(O)(ORI)2, n is an integer from 3 to 10000, R1and R2are the same or different and are independently a hydrogen, a halogen, a hydroxyl, a Ce-30 aryl, a Ci- 12 allyl, a C1-12 alkoxy, or a C1-12 alkyl group.In formula (12) representing the crosslinking group, A is -C(CH3)2-, -SO2-, -S-, or -O-, and q is 0 or 1.

[0049] In some aspects, the thermoplastic composition includes at least one cyclic phenoxyphosphazene having a structure represented by formula (13):In formula (13), Ri to Re can be the same of different and are independently an aryl group, an aralkyl group, a C1-12 alkoxy group, or a C1-12 alkyl group. For example, the cyclic phenoxyphosphazene may have a structure represented by formula (14):

[0050] Examples of suitable cyclic phenoxyphosphazene include, but are not limited to, a mixture of phosphazenes in which phenoxy groups and / or alkoxy groups are introduced as substituents and which are obtainable from a mixture of cyclic and straight-chain chlorophosphazenes, e.g., hexachlorocyclotriphosphazene, octachlorocyclotetra-phosphazene and the like, prepared by reacting ammonium chloride and phosphorus pentachloride at about 120°C to about 130°C; and hexaphenoxy cyclotriphosphazene, octaphenoxy cyclotetraphosphazene, decaphenoxycyclo-pentaphosphazene, hexaalkoxycyclotriphosphazene, octaalkoxycyclotetraphosphazene, decaalkoxycyclopenta-phosphazene and like cyclic phosphazenes obtained by isolating, from the above mixture of chlorophosphazenes, hexachlorocyclotriphosphazene, octachlorocyclotetraphosphazene, decachlorocyclopenta- phosphazene or like single substances, followed by substitution with a phenoxy group and / or an alkoxy group. In some aspects, the phosphorous flame retardant comprises a polyphosphonate and the type of polyphosphonate is not particularly limited. Exemplary polyphosphonates include those disclosed in, for example, U.S. Pat. No. 7,645,850 (Freitag), U.S. Publication No. 2007 / 0032633 (Freitag et al.), U.S. Pat. No. 8,841,367, U.S. Pat. No. 9,884,961, and U.S. Pat. No. 10,100,192, each being incorporated by reference herein.

[0051] The polyphosphonate may be a homopolymer or copolymer (e.g., with polycarbonate) and may be linear or branched. In some aspects, the polyphosphonate comprises a polymer containing repeating monomer units of CEE — PO(OH)2 or CEE — PO(OH) — OR, where R represents alkyl or aryl groups, or R'O — PO(R3) — OR2, where each R1and R2is aromatic or aliphatic group and R3is Ci-Ce alkyl or aromatic group. The polyphosphonate may have a weight average molecular weight of 10,000 g / mol or higher, including 20,000 g / mol or higher. Oligomers can also be used with a weight average molecular weight greater than 800 g / mol. Suitable commercially available polyphosphonates include Nofia™ HM1100 (polyphosphonate homopolymer), Nofia™ C06000 (polyphosphonate-co-carbonate polymer), and Nofia™ OL1001, Nofia™ OL3001, Nofia™ 3000, and Nofia 5000™ (polyphosphonate oligomers) by FRX Polymers, Inc. of Chelmsford, Mass., USA.Flame-retardant Synergist

[0052] The thermoplastic composition includes a flame-retardant synergist that has surprisingly demonstrated synergistic effects with the phosphorus flame retardant to improve flame retardancy of the thermoplastic composition. The flame-retardant synergist may be present in the thermoplastic composition in an amount of 0.5 wt.% to 10 wt.% based upon the total weight of the composition. For example, the flame-retardant synergist may be present in the thermoplastic composition in an amount of 1 wt.% to 9 wt.%, 2 wt.% to 8 wt.%, 3 wt.% to 6 wt.%, 3.5 wt.% to8 wt.%, or 4 wt.% to 8 wt.%, including all subranges and endpoints therebetween. In some aspects, the combined amount of the phosphorous flame retardant and the flame-retardant synergist is at least 5 wt.% based upon the total weight of the thermoplastic composition, including at least 7 wt.%, at least 10 wt.%, at least 12 wt.%, and at least 14 wt.%, including all subranges and endpoints therebetween.

[0053] The flame-retardant synergist may comprise an inorganic mineral. The inorganic mineral may comprise clay, silicate, mica, talc, wollastonite, or combinations thereof. Examples of suitable clay include, but are not limited to, kaolin clay, talc clay, and mixtures thereof. Suitable commercially available clays include Polyfil® Clays by KaMin LLC, Georgia, USA and ADINS® Clays by Tolsa, Madrid, Spain. Examples of suitable silicates include, but are not limited to, calcium silicate, potassium silicate, magnesium silicate, aluminum silicate, and mixtures thereof. In any of the aspects provided herein, the inorganic mineral may have a Brunauer-Emmett-Teller (BET) surface area of 1 m2 / g to 100 m2 / g, including, for example, 3 m2 / g to 80 m2 / g, 5 m2 / g to 50 m2 / g, 7 m2 / g to 30 m2 / g, 10 m2 / g to 25 m2 / g, and 15 m2 / g to 20 m2 / g, including all subranges and endpoints therebetween, based on BET surface area analysis with nitrogen as adsorbate. In any of the aspects provided herein, the inorganic mineral may have a median diameter of 0.1 micron to 30 microns, including, for example, 0.2 micron to 25 microns, 2 microns to 20 microns, 3 microns to 15 microns, and 4 microns to 10 microns, including all subranges and endpoints therebetween.Filler

[0054] The thermoplastic composition may further comprise a filler. In any of the aspects provided herein, the filler may be present in the thermoplastic composition in an amount of 0 wt.% to 10 wt.% based upon the total weight of the composition. For example, the filler may be present in the thermoplastic composition in an amount from greater than 0 wt.% to 10 wt.%, 1 wt.% to 9 wt.%, 2 wt.% to 8 wt.%, 3 wt.% to 8 wt.%, and 4 wt.% to 7 wt.%, including all subranges and endpoints therebetween.

[0055] In some aspects, the filler comprises a laser direct structuring (LDS) additive, a laser marking additive, or combinations thereof. The LDS additive enables the thermoplastic composition to be used in a laser direct structuring process. In an LDS process, a laser beam exposes the LDS additive to place it at the surface of the thermoplastic composition and to activate metal atoms from the LDS additive. After being exposed to laser beam, the laser-etched area is capable of being plated to form conductive structure. On the other hand, the laser marking additive causes color change in the material under the effect of energy radiation.

[0056] Examples of suitable LDS additives include, but are not limited to, spinel based metal oxides (e.g., copper chromium oxide), organic metal complexes (e.g., palladium / palladium-containing heavy metal complexes), copper complexes, metal oxides, metal oxide-coated fillers (e.g., metal oxide containing one or more of antimony, copper, zinc, tin, magnesium, aluminum, gold, and silver, coted on a mineral such as silica), and mixtures thereof, as described in PCT Patent Publication WO 2012 / 056416, fully incorporated herein.

[0057] The filler may also comprise an impact modifier. The impact modifier may comprise high molecular weight elastomeric materials derived from olefins, monovinyl aromatic monomers, acrylic and methacrylic acids and their ester derivatives, as well as conjugated dienes. The polymers formed from conjugated dienes can be fully or partially hydrogenated. The elastomeric materials can be in the form of homopolymers or copolymers, including random, block, radial block, graft, and core-shell copolymers. Examples of suitable impact modifiers include, but are not limited to, silicone-acrylic rubber (e.g., METABLEN S-series from Mitsubishi Chemical Group), acrylic core-shell impact modifiers (e.g., KM branded series from Rohm & Haas), methacrylate / butadiene / styrene core-shell impact modifiers (e.g., Clearstrength branded series from Arkema, Inc.), ethyl ene / n-butyl acrylate / glycidyl methacrylate terpolymers (e.g., Elvaloy branded series from DuPont), n-octyl acrylate rubber / polymethylmethacrylate core-shell impact modifier (e.g., D-400 from Arkema), a linear terpolymer of (a) ethylene, (b) a lower alkyl acrylate, and (c) a monomer which contains a heterocycle containing one oxygen atom as the hetero-atom (e.g., Lotader AX 8900 from Arkema), a styrene-butadiene-methacrylate terpolymer (e.g., as disclosed in PCT Patent Publication WO 2005 / 035666), a thermoplastic vulcanizate (e.g., OnFlex™ V from PolyOne Corporation and as disclosed in PCT Patent Publication WO 2005 / 071012), and combinations thereof.

[0058] In any of the aspects provided herein, the thermoplastic composition may be free of silicon-based impact modifier filler (e.g., silicone-acrylic rubber).

[0059] The filler may also comprise a reinforcement filler. Examples of suitable reinforcement fillers include, but are not limited to, glass fibers, carbon fibers, metal fibers, and combinations thereof. In any of the aspects provided herein, the thermoplastic composition may be free of reinforcement filler.Additives

[0060] The thermoplastic composition may further include one or more additives. Suitable additives include commercially available plastics additives, including additives available in the reference E. W. Flick, “Plastics Additives Database,” Plastics Design Library (Elsevier 2004). The additives may include antimicrobial agents, mold release agents, anti-oxidants, light stabilizers such as UV stabilizers, pigments, colorants, fire retardants, lubricants such as silicone- containing lubricants, molecular sieves, chain extenders, or combinations thereof. The one ormore additives may be included in the thermoplastic composition in any amount sufficient to obtain a desired processing or performance property for the thermoplastic composition and / or the thermoplastic article. The additives may be present in the thermoplastic composition in an amount of 0 wt.% to 3 wt.%, collectively or individually, including 0.1 wt.% to 2 wt.%, 0.1 wt.% to 1 wt.%, 0.1 wt.% to 0.5 wt.%, and 0.2 wt.% to 0.5 wt.%.

[0061] In any of the aspects provided herein, the thermoplastic composition may be free of perfluoroalkyl and polyfluoroalkyl substances (PF AS).Thermoplastic Pellet and Article

[0062] In an aspect provided herein, a thermoplastic pellet is disclosed, which comprises the thermoplastic composition described above. A method for producing the thermoplastic pellet may comprise mixing and extruding a thermoplastic masterbatch comprising the thermoplastic composition, and cutting the extruded masterbatch into pellets. The method may be performed with any conventional apparatus, such as, a conventional double screw extruder and a pelletizer.

[0063] In an aspect provided herein, a thermoplastic article is disclosed. The thermoplastic article comprises the thermoplastic composition described above and may be produced from the thermoplastic pellet by, for example, injection molding, blow molding, compression molding, extrusion, or any other suitable processes for forming plastic articles.

[0064] In some aspects, the thermoplastic article is formed with thin walls and thus may have a thickness of 2 mm or less, such as, for example a thickness of 1.6 mm or less, 1.5 mm or less, 1.2 mm or less, 1.0 mm or less, 0.8 mm or less, 0.6 mm or less, or 0.4 mm or less. In any of the aspects provided herein, the thermoplastic article may have a thin-wall flame retardancy of V- 2 or better, V-l or better, or V-0 or better under UL94 standard. For example, the thermoplastic article may be body panels of electronic devices such as VR headsets, True Wireless Stereo (TW S), mobile phones, notebook personal computers, e-books, and tablet personal computers.Flame Retardant Properties

[0065] The thin-wall flame retardancy of the thermoplastic composition and thermoplastic article formed therefrom can be evaluated by testing a specimen under UL94 standard. The UL94 standard provides six classifications: HB, V-2, V-l, V-0, 5VB, and 5VA, in the order from the lowest to the highest flame retardancy. The specimen is prepared by mixing and extruding the thermoplastic composition in a conventional extruder and molding the extruded material into the thicknesses to be tested. In any of the aspects provided herein, the thermoplastic composition may have a thin-wall flame retardancy of V-0 or better at 1.6 mm thickness, at 1.5 mm thickness, at 1.2 mm thickness, 1.0 mm thickness, at 0.8 mm thickness, at 0.6 mm thickness, or even at 0.4 mm thickness. In any of the aspects provided herein, the thermoplastic composition may have a thin-wall flame retardancy of V-l or better at 1.5 mm thickness, at 1.5 mm thickness, at 1.2 mm thickness, 1.0 mm thickness, at 0.8 mm thickness, at 0.6 mm thickness, or even at 0.4 mm thickness.Mechanical Properties

[0066] The impact strength of the thermoplastic composition and thermoplastic article formed therefrom, in particular notched Izod impact strength, can be evaluated by preparing and testing specimens under ASTM D256 standard. In any of the aspects provided herein, the thermoplastic composition or article formed therefrom may have a notched Izod impact strength of 100 J / m or more under ASTM D256, including 100 J / m or more, 200 J / m or more, 300 J / m or more, 400 J / m or more, 500 J / m or more, 600 J / m or more, and 700 J / m or more.

[0067] The flexural modulus and flexural strength of the thermoplastic composition and / or thermoplastic article formed therefrom can be evaluated by preparing and testing specimens under ASTM D790 standard. In any of the aspects provided herein, the thermoplastic composition and / or article formed therefrom may have a flexural modulus of 2,000 MPa or more under ASTM D790, including, for example, 2,200 MPa or more, 2,400 MPa or more, 2,600 MPa or more, 2,800 MPa or more, 3,000 MPa or more, 3,200 MPa or more, 3,400 MPa or more, 3,600 MPa or more, 3,800 MPa or more, and 3,900 MPa or more. In any of the aspects provided herein, the thermoplastic composition and / or article formed therefrom may have a flexural strength of 80 MPa or more under ASTM D790, including 85 MPa or more, 80 MPa or more, 90 MPa or more, 95 MPa or more, 100 MPa or more, and 105 MPa or more.

[0068] The tensile modulus, tensile strength at break, and tensile elongation at break of the thermoplastic composition and article formed therefrom can be evaluated by preparing and testing specimens under ASTM D638 standard. In any of the aspects provided herein, the thermoplastic composition may have a tensile modulus of 1,800 MPa or more under ASTM D638, including 1,800 MPa or more, 2,000 MPa or more, 2,100 MPa or more, 2,150 MPa or more, 2,200 MPa or more, 2,250 MPa or more, 2,300 MPa or more, 2,350 MPa or more, and 2,400 MPa or more.

[0069] With regards to tensile strength, the thermoplastic composition and article formed therefrom may have a tensile strength at break of 40 MPa or more under ASTM D638, including 45 MPa or more, 48 MPa or more, 50 MPa or more, 52 MPa or more, 54 MPa or more, and 56 MPa or more. In any of the aspects provided herein, the thermoplastic composition may have a tensile elongation at break of 25% or more under ASTM D638, including 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, and 80% or more.Examples

[0070] The materials used in the exemplary compositions are set forth in Table 1 below.TABLE 1Compounding Conditions

[0071] In the following Examples, the ingredients are pre-blended in the form of pellets or powder, and then mixed and extruded through a twin screw extruder. The extrudate is cooled by a water bath prior to pelletizing. The extruded pellets are then dried in a dehumidifying dryer for 4 hours at 120°C, and molded into test specimens. The specimens are tested for notched Izod impact strength, flame retardancy, tensile properties (tensile modulus, tensile strength at break, and tensile elongation at break), and flexural properties (flexural modulus and flexural strength). The testing standards and the molded specimen types are listed in Table 2.Test StandardsTABLE 2Example 1: Silicone-Based Impact Modifier

[0072] Thermoplastic compositions were prepared with the compositions detailed in Table 3 below. The Comparative Examples 1-1 and 1-2 were prepared with a silicone-based impact modifier (e.g., core-shell impact modifier S2030), which is commonly used in conventional thermoplastic compositions to improve impact strength. As shown in Table 3 below, Comparative Example 1-1 comprises pure polycarbonate (no copolymer) compounded with a phosphorus flame retardant, a flame-retardant synergist (clay), and a silicone-based impact modifier, which presented good impact strength but poor flame retardancy performance. In Comparative Example 1-2, 10 wt.% of silicone-polycarbonate copolymer was introduced and resulted in some improvements in flame retardancy as well as better impact strength. Example 1-1 comprised 10 wt.% of siliconepolycarbonate copolymer with no silicone-based impact modifier. Example 1-1 demonstrated an improved flame retardancy performance, achieving a rating of V-l at 0.8 mm thickness with no dripping, without any PTFE anti-dripping agent in the composition. As demonstrated by Example 2-1, by further increasing the amount of the silicone-polycarbonate copolymer (e.g., to 30 wt.%), it is possible to maintain a good flame retardancy performance while further improving the impact strength. It has been discovered that silicone-polycarbonate copolymer can improve impact strength, while also unexpectedly providing a synergistic improvement with phosphazene or phosphate flame retardants to improve flame retardancy of the composition.TABLE 3Example 2: Flame-Retardant Synergist

[0073] To demonstrate the effect of the flame-retardant synergist, thermoplastic compositions were prepared with 4 wt.% of different types of flame-retardant synergist (clay, talc, or mica) or no flame-retardant synergist. As shown in Table 4 below, Comparative Example 3-1 without any flame-retardant synergist did not present acceptable thin-wall flame retardancy, with a V-2 rating at 0.8 mm thickness. In contrast, Examples 5-1, 5-2, and 5-3, respectively comprising clay, mica, and talc as flame-retardant synergist, achieved V-0 or V-l ratings at 0.8 mm thickness. While each of the three flame-retardant synergists improved flame retardancy, the specimen with clay achieved better impact strength than the other two.TABLE 4lammability, Vertical Bum [1,6 mm V-0 V-0 V-0 V-0Example 3: Amount of Flame-Retardant Synergist

[0074] As shown in Table 5 below, thermoplastic compositions were prepared with various amounts of clay as flame-retardant synergist. When the amount of clay was reduced, the composition became less effective in flame retardancy (See, e.g., Comparative Example 2-1 with 2 wt.% clay and V-2 rating at 0.8 mm thickness), but it was possible to maintain a good flame retardancy by increasing the amount of the phosphorus flame retardant (Example 2-4 with 2 wt.% clay and 6 wt.% phosphazene FR agent). When the amount of clay was increased, a good flame retardancy was maintained but some drop in impact strength was observed (Example 3-1 with 8 wt.% clay).TABLE 5Example 4: Amount of Flame Retardant Agent

[0075] As shown in Table 6 below, thermoplastic compositions were prepared with various amounts of phosphorus flame retardant (phosphazene). As discussed above in connection with Table 5, higher amounts of phosphorus flame retardant may help achieve good flame retardancy even with less flame-retardant synergist (see Comparative Example 2-1 and Example 2-4). Comparing Examples 3-1, 3-2, and 3-3, it can be seen that flame retardancy became better with an increasing amount of phosphorus flame retardant, where V-0 ratings were achieved at 0.6 mm thickness and even 0.4 mm thickness. The specimens in Table 6 also maintained high impact strengths.TABLE 6Example 5: Flame Retardant Agent

[0076] Exemplary thermoplastic compositions were prepared to demonstrate the effect of different phosphorus flame retardants. As shown in Table 7 below, similar flame-retardant performances were observed in Example 2-1 (phosphazene fire retardant HPCTP) and Example 4-1 (phosphate fire retardant WSFR-PX-220). Example 4-1 was found to have slightly lower heat deflection temperature (HDT) than Example 2-1 as the melting point of PX-220 (90 °C) is lower than HPCTP (118 °C).TABLE 7Example 6: Compositions with LDS Additive

[0077] As inorganic filler, LDS additive can be included in the thermoplastic composition for applications in laser directing structure (LDS) technology. As shown in Table 8 below, specimens were prepared with LDS additive and different types of clay as flame-retardant synergist (Comparative Example 4-1, Comparative Example 4-2, and Example 6-1). It can be seen that the choice of flame-retardant synergist may affect the mechanical properties and flame retardancy in thermoplastic compositions comprising an LDS matrix.

[0078] Furthermore, thermoplastic compositions were prepared with the flame-retardant synergist that resulted in the best mechanical properties and flame retardancy (Polyfil HG90 clay).Example 6-1 and Example 6-2 demonstrate that good impact strength and flame-retardant performance (V-0 at 0.8mm thickness) can be achieved by incorporating silicone-block- polycarbonate, phosphorus flame retardant, and flame-retardant synergist into the LDS matrix, without any conventional PTFE anti-dripping agent. The silicone-block-polycarbonate can be included in various amounts (e.g., from 15 to 30 wt.%) and the thermoplastic composition still maintains good impact strength and flame retardancy. Example 6-3 was prepared without any silicone containing lubricant, which maintained the flame retardancy rating of V-0 at 0.8mm thickness. Although the impact strength decreased in comparison with Example 6-1 (1 wt.% lubricant), the specimen of Example 6-3 still had high impact strength with 389 J / m of notched Izod impact strength.

[0079] Post-consumer recycled (PCR) polycarbonate can be used together with, or in alternative to, the polycarbonate in the thermoplastic composition. As can be seen from Example 6-4 and Example 6-5, when virgin polycarbonate is replaced with PCR polycarbonate, the flameretardant performance remained the same but the impact strength dropped in comparison with Example 6-1 and Example 6-2, due to lower impact strength of PCR polycarbonate.TABLE 8

[0080] It will be apparent that modifications and variations are possible without departing from the scope of the disclosure defined in the appended claims. More specifically, although some aspects of the present disclosure are identified herein as preferred or particularly advantageous, it is contemplated that the present disclosure is not necessarily limited to these aspects.

Claims

CLAIMS1. A thermoplastic composition comprising, based on total weight of the thermoplastic composition:(a) from 40 to 85 wt.% of a polycarbonate;(b) from 10 to 50 wt.% of a silicone-block-poly carbonate;(c) from 2 to 15 wt.% of a phosphorus flame retardant;(d) from 1.0 to 10 wt.% of a flame-retardant synergist.

2. The thermoplastic composition of claim 1, wherein the phosphorus flame retardant comprises phenoxyphosphazene, bisphenol A-bis(diphenyl phosphate) (BPADP), resorcinol bis(diphenyl phosphate) (RDP), 1,4-phenylene tetraphenyl ester (PX-220), polyphosphonates, 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), DOPO derivatives, or combinations thereof.

3. The thermoplastic composition of claim 2, wherein the phosphorus flame retardant comprises cyclic phenoxyphosphazene.

4. The thermoplastic composition of any one of claims 1-3, wherein the flame-retardant synergist comprises an inorganic mineral.

5. The thermoplastic composition of claim 4, wherein the inorganic mineral comprises clay, silicate, mica, talc, or combinations thereof.

6. The thermoplastic composition of claim 4, wherein the inorganic mineral comprises clay.

7. The thermoplastic composition of claim 5 or claim 6, wherein the clay comprises kaolin clay, talc clay, and mixtures thereof.

8. The thermoplastic composition of any one of claims 1-7, wherein the composition includes a combined amount of phosphorous flame retardant and flame-retardant synergist that is at least 5 wt.%.

9. The thermoplastic composition of any one of claims 1-8, further comprising from greater than 0 to 10 wt.% of a filler.

10. The thermoplastic composition of claim 9, wherein the filler comprises LDS additive, laser marking additive, or combinations thereof.

11. The thermoplastic composition of any one of claims 1-10, wherein the thermoplastic composition is free of silicon-based impact modifier filler.

12. The thermoplastic composition of any one of claims 1-11, wherein the thermoplastic composition is free of reinforcement filler.

13. The thermoplastic composition of any one of claims 1-12, further comprising no more than 3 wt.% of an additive comprising an antioxidant, silicone-containing lubricant, light stabilizer, mold release agent, chain extender, colorant, or combinations thereof.

14. The thermoplastic composition of any one of claims 1-13, wherein the thermoplastic composition is free of perfluoroalkyl and polyfluoroalkyl substances (PF AS).

15. The thermoplastic composition of any one of claims 1-14, wherein the thermoplastic composition has a thin-wall flame retardancy, tested in accordance with UL94 standard, of at least V-0 at 1.6 mm thickness.

16. The thermoplastic composition of any one of claims 1-15, wherein the thermoplastic composition has a thin-wall flame retardancy, tested in accordance with UL94 standard, of at least V-l at 1.5 mm thickness.

17. The thermoplastic composition of any one of claims 1-16, wherein the thermoplastic composition has a thin-wall flame retardancy, tested in accordance with UL94 standard, of at least V-l at 0.8 mm thickness.

18. The thermoplastic composition of any one of claims 1-17, wherein the thermoplastic composition has a notched Izod impact strength of 100 J / m or more under ASTM D256.

19. The thermoplastic composition of any one of claims 1-18, wherein the thermoplastic composition has a flexural modulus of 2000 MPa or more, tested in accordance with ASTM D790.

20. The thermoplastic composition of any one of claims 1-19, wherein the thermoplastic composition has a flexural strength of 80 MPa or more, tested in accordance with ASTM D790.

21. The thermoplastic composition of any one of claims 1-20, wherein the thermoplastic composition has a tensile modulus of 1800 MPa or more, tested in accordance with ASTM D638.

22. The thermoplastic composition of any one of claims 1-21, wherein the thermoplastic composition has a tensile strength at break of 40 MPa or more, tested in accordance with ASTM D638.

23. The thermoplastic composition of any one of claims 1-22, wherein the thermoplastic composition has a tensile elongation at break of 25% or more, tested in accordance with ASTM D638.

24. A thermoplastic pellet comprising the thermoplastic composition of any one of claims 1- 23.

25. A method for producing a thermoplastic pellet, comprising: blending a thermoplastic masterbatch comprising the thermoplastic composition of any one of claims 1-23; extruding the thermoplastic masterbatch through an extruder; and cutting the extruded thermoplastic masterbatch into pellets with a pelletizer.

26. A thermoplastic article formed from the thermoplastic composition of any one of claims 1- 23.

27. The thermoplastic article of claim 26, wherein the thermoplastic article is a body panel of an electronic device selected from VR headsets, True Wireless Stereo (TWS), mobile phones, notebook personal computers, e-books, and tablet personal computers.

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