Flame-retardant polycarbonate composition

Abstract

The present invention relates to a composition comprising or consisting of: (a) at least one poly (carbonate-siloxane) copolymer present in an amount of 25.0 to 55.0 wt%, based on the total weight of the composition; (b) at least one brominated polycarbonate present in an amount of 25.0% to 55.0% by weight; (c) glass fibers present in an amount of from 12.0 wt% to 20.0 wt%; and (d) at least one polycarbonate homopolymer present in an amount of 6.0% to 20.0% by weight, based on the total weight of the composition. The invention further relates to articles prepared from such compositions and to the use of such compositions.

Description

Technical Field

[0001] The present invention relates to polycarbonate compositions having improved flame retardant properties and to articles prepared from such polycarbonate compositions. The present invention further relates to the use of such polycarbonate compositions for improving the flame retardant properties of components used in mass transportation. Background Art

[0002] Although most thermoplastics are readily combustible, a major requirement for using such materials in the interior of mass transportation vehicles is to comply with the fire resistance / flame retardancy requirements set by different regulatory codes. For example, the European railway industry is regulated by EN 45545-2, which consists of three tests: heat release, smoke density, and flame spread. These define the standards that materials need to meet in order to be used in the interior of trains. The said code sets different risk and hazard levels, which define the flame retardancy standards that materials need to meet for some applications. The risks are classified using a numerical range from 1 (the most stringent) up to 26 (less stringent), where 1 is related to horizontal and vertical interior surfaces (such as ceilings, walls, window frames, or displays), and 26 is related to small electronic components.

[0003] The said hazard levels are related to the design and operation of rail vehicles and are three: HL1 (less stringent), HL2, and HL3 (the most stringent). Specifically, in order to comply with EN 45545-2 R1-HL2, a sample must have a heat release (less than or equal to) ≤90.0 kW / m 2 , Ds4 (less than or equal to) ≤300.0, VOF4 (less than or equal to) ≤600.0 (referring to smoke density), and CFE (greater than or equal to) ≥20.0 kW / m 2 (referring to flame spread).

[0004] Due to some inherent advantages, such as its mechanical properties, relatively low density, ease of processing, and ability to alter long-term stability, polycarbonate-based materials are of high interest in the mass transportation industry for making interior components of trains and airplanes. Additionally, from the perspective of cost as a sustainability consideration, for example, in terms of the CO2 emissions reduction provided by polycarbonate compared to competing materials (such as aluminum or thermosetting materials), the interest in using polycarbonate-based materials for interior components of mass transportation systems is increasing, which requires meeting strict combustion regulatory standards. Due to the challenges in enhancing flame retardant properties, the use of polycarbonate-based materials is currently limited to a few specific applications, such as handrails or lighting, where the said code is relatively less stringent or there are no regulatory requirements.

[0005] In the past, a possible solution to improve the flame retardant / fire resistant properties of thermoplastic materials was to compound the polymer with flame retardant additives. However, the flame retardant additives need to be selected and used judiciously and in limited amounts because overuse of such additives can affect polymer properties such as rheological and mechanical properties, thus affecting the processing of such polymers.

[0006] An alternative solution for improving the flame retardant properties of polycarbonates is to use polar functionalized polymers such as polyetherimides. For example, industry practitioners have previously developed polyetherimide (PEI), polyphenylene oxide (PPO), which impart fire resistance / flame retardancy to polycarbonate-based materials. However, such polar functionalized polymers exhibit processing-related drawbacks due to their higher density, lower mechanical properties, and significantly higher cost, and may thus be undesirable for price-sensitive and high-performance demanding markets such as the railway and aircraft industries.

[0007] Accordingly, one objective of the present invention is to provide a polycarbonate-based composition having desired flame retardant properties and being useful for mass transportation applications. Another objective of the present invention is to provide such a composition that meets the requirements of EN 45545-2 R1-HL2 without the need to add additional flame retardants. Another objective of the present invention is to provide an article prepared from such a polycarbonate-based composition that meets the EN 45545-2 R1-HL2 flame retardant requirements. Summary of the Invention

[0008] Accordingly, one or more objectives of the present invention are achieved by a composition that comprises or consists of, based on the total weight of the composition:

[0009] (a) 25.0 wt% - 55.0 wt% of at least one poly(carbonate-siloxane) copolymer;

[0010] (b) 25.0 wt% - 55.0 wt% of at least one brominated polycarbonate;

[0011] (c) 6.0 wt% - 20.0 wt% of at least one polycarbonate homopolymer; and

[0012] (d) 12.0 wt% to less than 20.0 wt% of glass fibers; wherein the polycarbonate homopolymer is bromine-free.

[0013] The sum of components (a)-(d) and any optional additives is 100 wt%. If present in the composition, the optional additive may be present in an amount not greater than 5.0 wt%, preferably not greater than 2.5 wt%, preferably not greater than 1.0 wt%, based on the total weight of the composition.

[0014] Preferably, based on the total weight of the composition:

[0015] (a) The poly(carbonate-siloxane) copolymer is present in an amount of 30.0 wt% - 50.0 wt%, preferably 35.0 wt% - 45.0 wt%;

[0016] (b) The brominated polycarbonate is present in an amount of 25.0 wt% - 39.0 wt%, preferably 30.0 wt% - 39.0 wt%; and

[0017] (c) The polycarbonate homopolymer is present in an amount of 8.0 wt% - 18.0 wt%.

[0018] The polycarbonate homopolymer does not contain bromine, such that such a homopolymer is different from the brominated polycarbonate. The term "does not contain bromine" means that the polycarbonate homopolymer contains 0.0 wt% of polymer units containing atomic bromine or bromine-based compounds.

[0019] Advantageously, the inventors have found that articles prepared from the compositions of the present invention exhibit excellent flame retardant properties and meet the standards of EN 45545-2 specifications. Specifically, articles prepared from the compositions of the present invention meet the strict R1-HL2 EN 45545-2 standard, where the article has a material thickness of at most 3 mm. Although the flame retardancy of polycarbonate-based compositions has been known in the past and used in railway and aerospace components, the present invention specifically addresses the requirements of the R1-HL2 EN45545-2 standard.

[0020] The composition contains less than 0.5 wt%, preferably less than 0.01 wt%, preferably 0.0 wt% of additional flame retardant compounds based on the total weight of the composition. Preferably, the additional flame retardant compounds are selected from organic phosphates / salts, polyetherimide (PEI), polyphenylene ether (PPE), aromatic organic phosphorus compounds having two or more phosphorus-containing groups, organic compounds containing phosphorus-nitrogen bonds, halogenated flame retardants, inorganic flame retardants, and combinations thereof.

[0021] The term "additional flame retardant compound" refers to a flame retardant compound other than the poly(carbonate-siloxane) copolymer, polycarbonate homopolymer, brominated polycarbonate, and glass fiber, which may or may not have some flame retardant properties of its own.

[0022] The inventors have found that the composition exhibits the R1-HL2 EN 45545-2 ("HL2") standard even without using any additional flame retardant compounds.

[0023] For example, the composition has the following or is selected to have the following:

[0024] · The smoke density (Ds4) after 4 minutes which is less than or equal to 300.0, preferably less than or equal to 250.0, preferably less than or equal to 200.0, preferably less than or equal to 150.0, preferably less than or equal to 130.0, measured according to ISO 5659-2 on a 3-mm thick board at 50.0 kW / m 2 ;

[0025] · The smoke density (VOF4) which is less than or equal to 600.0, preferably less than or equal to 500.0, preferably less than or equal to 400.0, preferably less than or equal to 300.0, preferably less than or equal to 250.0, measured according to ISO 5659-2 on a 3.0-mm thick board at 50.0 kW / m 2 ;

[0026] · The maximum average heat release (MAHRE) which is less than or equal to 90.0 kW / m 2 , preferably less than or equal to or less than 80.0 kW / m 2 , preferably less than or equal to or less than 60.0 kW / m 2 , measured according to ISO 5660-1 on a 3-mm thick board at 50 kW / m 2 ; and

[0027] · The critical heat flux at extinguishment (CFE) which is greater than or equal to 20.0 kW / m 2 , preferably greater than or equal to 22.0 kW / m 2 , preferably greater than or equal to 25.0 kW / m 2 , measured according to ISO 5658-2

[0028] The composition may have a smoke density (Ds4) after 4 minutes which is from 55.0 to less than or equal to 300.0, preferably from 60.0 to less than or equal to 250.0, preferably from 60.0 to less than or equal to 200.0, preferably from 55.0 to less than or equal to 200.0, preferably from 60.0 to less than or equal to 100.0, measured according to ISO 5659-2 on a 3.0-mm thick board at 50.0 kW / m 2 ;

[0029] The composition may have a... measured according to ISO 5659-2 on a 3.0-mm thick board at 50.0 kW / m 2The smoke density (VOF4) measured below is from 55.0 to less than or equal to 600.0, preferably from 80.0 to less than or equal to 550.0, preferably from 100.0 to less than or equal to 500.0, preferably from 100.0 to less than or equal to 500.0, preferably from 100.0 to less than or equal to 300.0, preferably from 100.0 to less than or equal to 250.0.

[0030] The composition may have a maximum average heat release (MAHRE) of from 25.0 to less than or equal to 90.0 kW / m 2 measured on a 3-mm thick plate according to ISO 5660-1 at 50 kW / m 2 , preferably from 35.0 to less than or equal to or less than 80.0 kW / m 2 , preferably from 40.0 to less than or equal to or less than 60.0 kW / m 2 .

[0031] The composition may have a critical heat flux at extinguishment (CFE) of greater than or equal to 20.0 kW / m 2 to at most 40.0 kW / m 2 , preferably greater than or equal to 22.0 kW / m 2 to at most 35.0 kW / m 2 , preferably greater than or equal to 25.0 kW / m 2 to a maximum of 35.0 kW / m 2 .

[0032] Thus, in one aspect of the present invention, the present invention relates to an article comprising the composition of the present invention, preferably wherein the article is suitable for use in a mass transportation system. Preferably wherein the article is at least any one of a railway component, an aerospace component or an automotive component. The article may comprise the composition of the present invention in an amount of at least 90.0% by weight, preferably at least 95.0% by weight, preferably at least 98.0% by weight, preferably at least 99.0% by weight, preferably 100% by weight based on the total weight of the article.

[0033] In another aspect of the present invention, the present invention relates to the use of the composition according to the present invention for improving the flame retardant properties of articles used in mass transportation systems.

[0034] In yet another aspect of the present invention, the composition does not contain a poly(carbonate-siloxane-arylate ester) copolymer, wherein the poly(carbonate-siloxane-arylate) copolymer comprises repeating units of aromatic carbonate units, siloxane units and aromatic ester (arylate) units or consists of repeating units of aromatic carbonate units, siloxane units and aromatic ester (arylate) units.

[0035] Poly(carbonate-siloxane) copolymer

[0036] The composition comprises a poly(carbonate-siloxane) copolymer, also known in the art as polysiloxane-polycarbonate or poly(diorganosiloxane)-carbonate.

[0037] The amount of the poly(carbonate-siloxane) copolymer present may be 25.0 wt% - 55.0 wt%, preferably 30.0 wt% - 50.0 wt%, more preferably 35.0 wt% - 45.0 wt% based on the total weight of the composition.

[0038] The poly(carbonate-siloxane) copolymer comprises repeating units of aromatic carbonate units and siloxane units or consists of repeating units of aromatic carbonate units and siloxane units. The poly(carbonate-siloxane) copolymer may comprise 70.0 - 98.0 wt%, preferably 75.0 - 97.0 wt% of aromatic carbonate units based on the total weight of the poly(carbonate-siloxane) copolymer. The poly(carbonate-siloxane) copolymer may comprise 2.0 - 30.0 wt%, preferably 3.0 - 25.0 wt% of siloxane units based on the total weight of the poly(carbonate-siloxane) copolymer.

[0039] Preferably, the silicon content of the poly(carbonate-siloxane) copolymer is less than 3.0 wt%, preferably less than 1.5 wt%, more preferably the silicon content is 1.0 wt% based on the total weight of the poly(carbonate-siloxane) copolymer.

[0040] Preferably, the silicon content of the poly(carbonate-siloxane) copolymer is greater than 0.0 wt% and less than 3.0 wt%, preferably greater than 0.0 and less than 1.5 wt%, more preferably the silicon content is 1.0 wt% based on the total weight of the poly(carbonate-siloxane) copolymer.

[0041] The poly(carbonate-siloxane) copolymer may have an Mw of 2,000 - 100,000 g / mol, preferably 5,000 - 50,000 g / mol, more preferably 25,000 - 40,000 g / mol. The molecular weight used herein is measured by gel permeation chromatography using a cross-linked styrene-divinylbenzene column at a sample concentration of 1 mg / mL and calibrated with polycarbonate standards. The poly(carbonate-siloxane) copolymer may have a polydispersity index of 2.0 - 3.0.

[0042] Aromatic carbonate unit

[0043] The aromatic carbonate unit is a repeating unit of formula (1):

[0044]

[0045] where at least 60% of the total number of R 1 groups are aromatic, or each R 1 contains at least one C 6-30 aromatic group.

[0046] Specifically, each R 1 may be derived from a dihydroxy compound such as an aromatic dihydroxy compound of formula (2) or a bisphenol of formula (3).

[0047]

[0048] In formula (2), each R h is independently a halogen atom such as bromine, a C 1-10 hydrocarbon group such as a C 1-10 alkyl group, a halogen-substituted C 1-10 alkyl group, a C 6-10 aryl group or a halogen-substituted C 6-10 aryl group, and n is 0 - 4.

[0049] In formula (3), R a and R b are each independently a halogen, a C 1-12 alkoxy group or a C 1-12 alkyl group, and p and q are each independently an integer from 0 - 4 such that when p or q is less than 4, the valence of each carbon in the ring is filled with hydrogen.

[0050] Preferably, each of p and q is 0, or each of p and q is 1, and R a and R b are each a C 1-3 alkyl group, especially a methyl group, which is in the meta position to the hydroxyl group on each arylene group. X ais a bridging group connecting two hydroxy-substituted aryl groups, where the bridging group and the hydroxy substituents on each C6 arylene group are in the ortho, meta, or para (especially para) positions to each other on the C6 arylene group, for example, a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, or C 1-18 an organic group, which can be cyclic or acyclic, aromatic or non-aromatic, and can further contain heteroatoms such as halogen, oxygen, nitrogen, sulfur, silicon, or phosphorus.

[0051] such as X a can be a substituted or unsubstituted C 3-18 cycloalkylene; a C c substituted by —C(R d )(R 1-25 )—, where R c and R d are each independently hydrogen, C 1-12 alkyl, C 1-12 cycloalkyl, C 7-12 arylalkyl, C 1-12 heteroalkyl, or a cyclic C 7-12 heteroarylalkyl; or a group of the formula —C(═R e )—, where R e is a divalent C 1-12 hydrocarbyl group.

[0052] Preferably, the aromatic carbonate units present in the poly(carbonate-siloxane) copolymer can include aromatic carbonate repeating units of the following formula:

[0053]

[0054] where R a and R b are each independently C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy, p and q are each independently 0-4, and X a is a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, a C c substituted by —C(R d )(R 1-11 )—, where R c and R d are each independently hydrogen or C 1-10 alkyl, or a group of the formula —C(═R e )—, where R e is a divalent C 1-10 hydrocarbyl group, preferably X a is of the formula —C(Rc )(R d )—C 1-11 alkylene, where R c and R d are each independently C 1-6 alkyl.

[0055] Preferably, the aromatic carbonate units are selected from bisphenol A carbonate units, resorcinol carbonate units, and combinations thereof. Preferably, the aromatic carbonate units are derived from bisphenol A carbonate units and resorcinol carbonate units.

[0056] Siloxane unit

[0057] The siloxane units of the poly(carbonate-siloxane) copolymer are present as poly(diorganosiloxane) (also referred to herein as "polysiloxane") blocks, which contain repeating diorganosiloxane ("siloxane") units as in formula (7)

[0058]

[0059] where each 'R' is independently a C 1-13 monovalent organic group. For example, 'R' can independently be selected from C1-C 13 alkyl, C1-C 13 alkoxy, C2-C 13 alkenyl, C2-C 13 alkenyloxy, C3-C6 cycloalkyl, C3-C6 cycloalkoxy, C6-C 14 aryl, C6-C 10 aryloxy, C7-C 13 aralkyl, C7-C 13 aralkoxy, C7-C 13 alkylaryl, or C7-C 13 alkylaryloxy. The foregoing groups can be fully or partially halogenated with fluorine, chlorine, bromine, or iodine, or a combination thereof. Preferably, in the case of a desired transparent polysiloxane-polycarbonate, 'R' is unsubstituted by halogen. Combinations of the foregoing 'R' groups can be used in the same copolymer.

[0060] The value of 'E' in formula (7) may vary widely depending on considerations such as the type and relative amount of each component in the copolymer and the composition containing the copolymer, the desired properties of the composition, etc. Generally, E may have an average value of 2.0-1000, preferably 2.0-500.0, preferably 2.0-200.0, preferably 2.0-100.0, preferably 5.0-60.0, preferably 5.0-50.0, preferably 5.0-20.0. Preferably 2.0-200.0, preferably 2.0-125.0, preferably 5.0-125.0, preferably 5.0-100.0, preferably 5.0-50.0, preferably 20.0-80.0, preferably 5.0-20.0.

[0061] The preferred range of 'E' is 5.0-25.0, preferably 5.0-15.0, preferably 30.0-80.0, preferably 30.0-70.0.

[0062] Preferably the siloxane block is of formula (8)

[0063]

[0064] wherein 'E' is as defined in formula (7); each 'R' may be the same or different and is as defined above; and 'Ar' may be the same or different and is a substituted or unsubstituted C6-C 30 Arylene groups wherein the bond is directly to the aromatic moiety.

[0065] The 'Ar' group in formula (8) may be derived from a C6-C 30 The dihydroxyarylene compound can be selected from 1,1-bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)n-butane, 2,2-bis(4-hydroxy-1-methylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, bis(4-hydroxyphenyl sulfide), and 1,1-bis(4-hydroxy-tert-butylphenyl)propane. Combinations comprising at least one of the foregoing dihydroxy compounds can also be used.

[0066] Preferably, the 'Ar' group is derived from resorcinol. Preferably, the 'Ar' group is derived from bisphenol A.

[0067] Preferably, the polydiorganosiloxane block is of formula (9)

[0068]

[0069] Where 'R' and 'E' are as described in Equation (7), and each R5 independently is a divalent C1-C 30 organic group, and wherein the polymerized polysiloxane units are the reaction residues of their corresponding dihydroxy compounds.

[0070] Preferably, the polydiorganosiloxane block is of formula (10):

[0071]

[0072] wherein 'R' and 'E' are as defined above. R in formula (10) 6 is a divalent C2-C8 aliphatic group. Each M in formula (10) can be the same or different and can be halogen, cyano, nitro, C1-C8 alkylthio, C1-C8 alkyl, C1-C8 alkoxy, C2-C8 alkenyl, C2-C8 alkenoxy, C3-C8 cycloalkyl, C3-C5 cycloalkoxy, C6-C 10 aryl, C6-C 10 aryloxy, C7-C 12 aralkyl, C7-C 12 aralkoxy, C7-C 12 alkylaryl or C7-C 12 alkylaryloxy, wherein each n is independently 0, 1, 2, 3 or 4.

[0073] Preferably, the siloxane unit is of the following formula:

[0074]

[0075] or a combination comprising at least one of the foregoing, wherein 'E' has an average value of 2.0 - 200.0, preferably 2.0 - 125.0, preferably 5.0 - 125.0, preferably 5.0 - 100.0, preferably 5.0 - 50.0, preferably 20.0 - 80.0, preferably 5.0 - 20.0.

[0076] Preferably, the poly(carbonate-siloxane) copolymer comprises repeating units derived from or consists of repeating units derived from:

[0077] (i) aromatic carbonate units of the following formula:

[0078]

[0079] wherein R a and R b are each independently C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl or C 1-12 alkoxy, p and q are each independently 0 - 4, and X ais a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, the formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d are each independently hydrogen or C 1-10 alkyl, or a group of the formula —C(═R e )—, wherein R e is a divalent C 1-10 hydrocarbyl group, preferably X a is the formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d are each independently C 1-6 alkyl, preferably the aromatic carbonate unit is derived from bisphenol A carbonate; and

[0080] (ii) a siloxane unit selected from the following formula:

[0081]

[0082] and any combination thereof, wherein 'E' has an average value of 2.0 - 200.0.

[0083] Preferably, the poly(carbonate - siloxane) copolymer comprises repeating units derived from bisphenol A (BPA) carbonate repeating units and dimethylsiloxane units or consists of repeating units derived from bisphenol A (BPA) carbonate repeating units and dimethylsiloxane units.

[0084] For example, the poly(carbonate - siloxane) copolymer can be as shown in formula (25), wherein 'x' is an integer from 1 - 100, or 5 - 85, or 10 - 70, or 15 - 65, or 40 - 60; y is an integer from 10 - 30, and z is an integer from 450 - 600.

[0085]

[0086] Polycarbonate homopolymer

[0087] The composition comprises at least one polycarbonate homopolymer. The amount of the polycarbonate homopolymer present can be 6.0 wt% - 20.0 wt%, preferably 5.0 wt% - 18.0 wt%, preferably 5.0 wt% - 15.0 wt%, preferably 10.0 wt% - 18.0 wt%, preferably 12.0 wt% - 20.0 wt%, preferably 12.0 wt% - 18.0 wt% based on the total weight of the composition.

[0088] The polycarbonate homopolymer may be selected from linear polycarbonate homopolymers, branched polycarbonate homopolymers, and combinations thereof.

[0089] Preferably, the polycarbonate homopolymer is such a linear polycarbonate homopolymer that contains or consists of aromatic carbonate repeating units of the following formula:

[0090]

[0091] wherein R a and R b are each independently C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl, or C 1-12 alkoxy, 'p' and 'q' are each independently integers from 0 to 4, and X a is a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, an alkylene of the formula —C(R c )(R d )—, wherein R 1-11 and R c are each independently hydrogen or C d alkyl, or a group of the formula —C(═R 1-10 )—, wherein R e is a divalent C e hydrocarbyl. 1-10

[0092] Preferably, X a is an alkylene of the formula —C(R c )(R d )—, wherein R 1-11 and R c are each independently C d alkyl. Preferably, the linear polycarbonate homopolymer contains or consists of repeating units derived from bisphenol A carbonate. 1-6

[0093] The polycarbonate homopolymer may have a weight-average molecular weight (Mw) of 10,000 - 50,000 g / mol. The molecular weight used herein is measured by gel permeation chromatography using a cross-linked styrene-divinylbenzene column at a sample concentration of 1 mg / mL and calibrated with polycarbonate standards.

[0094] The branched polycarbonate homopolymer may contain repeating units derived from aromatic carbonate units and units derived from a branching agent. The repeating aromatic carbonate units may have the following formula:

[0095]

[0096] wherein R a and R b are each independently C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl or C 1-12 alkoxy, p and q are each independently 0 - 4, and X a is a bridging group between two arylene groups and is a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, a C c sub - alkyl of the formula —C(R d )(R 1-11 )—, wherein R c and R d are each independently hydrogen or C 1-10 alkyl, or a group of the formula —C(═R e )—, wherein R e is a divalent C 1-10 hydrocarbyl group.

[0097] The branching agent may comprise trimellitic trichloride, 1,1,1 - tris(4 - hydroxyphenyl)ethane or a combination of trimellitic trichloride and 1,1,1 - tris(4 - hydroxyphenyl)ethane. The amount of the branching agent present may be greater than or equal to 0.2 mol% based on the total moles of the branched polycarbonate.

[0098] Brominated polycarbonate

[0099] h The composition comprises a brominated polycarbonate. For example, the brominated polycarbonate may be of formula (2) and includes at least one R 1-10 which is bromine, bromine - substituted C 6-10 alkyl or bromine - substituted C a aryl. Alternatively, the brominated polycarbonate of formula (3) may include at least one R b or R

[0100] (which is bromine).

[0101] Preferably, the brominated polycarbonate comprises or consists of repeating units derived from: (i) brominated aromatic carbonate repeating units derived from 2,2’,6,6’ - tetrabromo - 4,4’ - isopropylidenediphenol; and (ii) aromatic carbonate repeating units derived from bisphenol A.

[0102] The amount of the brominated polycarbonate present may be 25.0 wt% - 55.0 wt%, preferably 25.0 wt% - 40.0 wt%, preferably 25.0 wt% - 39.0 wt%, preferably 30.0 wt% - 39.0 wt%, based on the total weight of the composition.

[0103] Glass fiber

[0104] The composition may comprise a variety of glass fibers. The glass fibers may be flat or round fibers. The flat glass fibers may have an oval cross-section, while the round fibers have a circular cross-section, where the cross-section is measured perpendicular to the longitudinal axis of the fiber.

[0105] The glass fibers may be made of "E-glass", "A-glass", "C-glass", "D-glass", "R-glass", "S-glass", and E-glass derivatives without fluorine and / or boron. The glass fibers may have a diameter of 3 - 35 microns. The glass fibers may have a diameter of 3 - 25 microns, or 4 - 20 microns, or 8 - 15 microns. The glass fibers may comprise woven or non-woven fibers, such as forming a reinforcing layer. The glass fibers may comprise chopped fibers. The chopped fibers may have a length of 0.5 millimeters (mm) - 2 centimeters (cm), or 1 mm - 1 cm. The glass fibers may be non-bonded or bonded. An example of the bonded glass fiber is T-120, which is commercially available from Nippon Electric Glass Co., Ltd.

[0106] The amount of the glass fibers present may be 12.0 wt% - 20.0 wt%, preferably 12.0 wt% - 18.0 wt%, based on the total weight of the composition.

[0107] The presence of the glass fibers not only provides hardening of the carbonaceous protective layer produced by the poly(carbonate-siloxane) copolymer, but also helps to synergistically combine with the polycarbonate homopolymer to improve heat release and reduction of flame spread.

[0108] Preferably, the composition comprises glass fibers, the amount of the glass fibers present is 12.0 wt% - 20.0 wt%, preferably 12.0 wt% - 18.0 wt%, based on the total weight of the composition; and the amount of the polycarbonate homopolymer present is 10.0 wt% - 18.0 wt%, preferably 12.0 wt% - 18.0 wt%, based on the total weight of the composition.

[0109] The inventors further found that when using other additives or fillers such as titanium oxide, the flame properties imparted to the composition are not as effective as when using titanium oxide.

[0110] Preferably, the composition comprises or consists of the following based on the total weight of the composition:

[0111] (a) 30.0 wt% - 50.0 wt% of at least one poly(carbonate - siloxane) copolymer;

[0112] (b) 25.0 wt% - 39.0 wt% of at least one brominated polycarbonate;

[0113] (c) 10.0 wt% - 18.0 wt% of at least one polycarbonate homopolymer; and

[0114] (d) 12.0 wt% to less than 18.0 wt% of glass fiber; wherein the polycarbonate homopolymer is bromine - free.

[0115] Preferably, the composition comprises or consists of the following based on the total weight of the composition:

[0116] (a) 35.0 wt% - 45.0 wt% of at least one poly(carbonate - siloxane) copolymer;

[0117] (b) 30.0 wt% - 39.0 wt% of at least one brominated polycarbonate;

[0118] (c) 10.0 wt% - 18.0 wt% of at least one polycarbonate homopolymer; and

[0119] (d) 12.0 wt% to less than 18.0 wt% of glass fiber; wherein the polycarbonate homopolymer is bromine - free.

[0120] Additive

[0121] An additive component can be used, which comprises one or more additives selected to impart desired properties. The additive composition or individual additives can be mixed at an appropriate time during the mixing of the components forming the composition.

[0122] The additive component can include antioxidants, impact modifiers, flow modifiers, fillers (such as particulate polytetrafluoroethylene (PTFE), glass particles (such as spheres other than fibers), carbon, minerals or metals), reinforcing agents (such as other than glass fibers), heat stabilizers, light stabilizers, ultraviolet (UV) light stabilizers, UV - absorbing additives, plasticizers, lubricants, parting agents (such as mold release agents), antistatic agents, antifogging agents, antimicrobials, colorants (such as dyes or pigments), surface - effect additives, radiation stabilizers, additional flame retardants, anti - drip agents (such as PTFE - encapsulated styrene - acrylonitrile copolymer (TSAN)) or combinations thereof.

[0123] The composition may include a combination of pigments, such as titanium dioxide, carbon black, and chromium titanate. Generally, the additives are used in amounts that are generally known to be effective.

[0124] For example, the total amount of additive components (except for any impact modifier or filler) may be 0.0 - 5.0 wt%, preferably 0.001 - 2.0 wt%, more preferably 0.01 - 1.0 wt%, each based on the total weight of the composition.

[0125] Preparation method

[0126] The composition can be prepared, for example, by melt - mixing a poly(carbonate - siloxane) copolymer, a brominated polycarbonate, glass fiber, and a polycarbonate homopolymer in a batch mixer. The composition can be prepared by extruding the components in a twin - screw extruder to form an extruded composition. The mixed or extruded composition is formed into the desired shape. There is no limitation on the forming method, and it can include methods such as extrusion, molding, coating, lamination, etc.

[0127] The present invention will now be further illustrated based on the following non - limiting examples. Examples

[0128] Purpose: Demonstrate the flame - retardant effect of the composition having the formulation prepared according to the present invention and compare such properties with a control formulation.

[0129] Materials: For the purposes of this example, the following materials are used:

[0130] Table 1

[0131]

[0132] Method for preparing samples: In The compositions used in the examples are prepared by first extruding the components in a twin - screw extruder under the processing conditions described in Table 2A to form an extruded composition. Then the extruded composition is dried and extruded into sheets of different thicknesses 400 mm wide using a Cincinnati extruder under the processing parameters described in Table 2B.

[0133] As used herein, °C represents degrees Celsius, rpm represents revolutions per minute, kg / h represents kilograms per hour, and m / min represents meters per minute.

[0134] Table 2A

[0135]

[0136]

[0137] Table 2B

[0138] Parameter Unit Value Temperature of Region 1 ℃ 190 Temperature of Region 2 ℃ 200 Temperature of Region 3 ℃ 210 Temperature of Region 4 ℃ 225 Temperature of Region 5 ℃ 235 Temperature of Region 6 ℃ 240 Temperature of Region 7 ℃ 250 Temperature of Region 8 ℃ 260 Roller 1 ℃ 120 Roller 2 ℃ 125 Roller 2 ℃ 130 Roller speed m / min 0.4

[0139] Test standard: The flame retardancy characterization of Examples 1 - 6 was carried out according to EN 45545 - 2 and included measurements of heat release (ISO 5660 - 1), smoke density (ISO 5659 - 2), and flame spread (ISO 5658 - 2). The requirements needed to receive a passing rating according to R1 - HL2 and R1 - HL3 are listed in Table 3. The R1 - HL2 and R1 - HL3 requirements were measured using 3.0 mm thick samples.

[0140] Table 3

[0141]

[0142] Different compositions were prepared via an experimental design (DOE) protocol using a mixture design space, and the flame ratings were analyzed according to the EN 45545 - 2 specification.

[0143] Results and conclusions: Table 4 provides the relative amounts of the sample components.

[0144] Table 4

[0145]

[0146] Table 5 provides the flame retardant properties of the samples.

[0147] Table 5

[0148] <![CDATA[Heat release / kW / m 2 > Ds4 VOF4 CE4 Tests complied with IE1 64.2 260 506 21 HL2 IE2 66.4 256 577 23.7 HL2 IE3 61.7 179 207 20 HL2 IE4 46 286 414 22.8 HL2 CE1 67.1 289 610 25 Failed CE2 58.8 309 581 23.5 Failed CE3 66.3 353 638 25.4 Failed CE4 63 311 597 23 Failed CE5 61 316 591 25 Failed

[0149] It can be clearly seen from the data provided in Table 5 that the samples prepared according to the present invention passed the HL2 flame retardancy test. Therefore, the articles prepared from these formulations can be used in mass transportation systems that require strict compliance with these test standards.

[0150] From the above table, the presence of each component in a specific ratio relative to the other components helps to meet the requirements of HL2.

[0151] In addition, the present inventors have found that even when the formulations use the same components but are blended in different proportions, the desired flame retardant properties cannot be obtained. For example, compared with IE1-IE4, comparative sample CE1 has the same components but is blended in different proportions. However, each of the IE1-IE4 samples passed the HL2 flame retardant test, while sample CE1 did not. This is surprising because although the poly(carbonate-siloxane) copolymer used in the examples has a certain degree of flame retardant properties, it is clear that the desired flame retardant effect under the HL2 standard can only be achieved when the components are formulated in the proportions specified in the present invention, even without the addition of additional flame retardant additives.

Claims

1. A composition comprising or consisting of, based on the total weight of the composition: (a) 25.0 wt% - 55.0 wt% of at least one poly(carbonate - siloxane) copolymer; (b) 25.0 wt% - 55.0 wt% of at least one brominated polycarbonate; (c) 6.0 wt% - 20.0 wt% of at least one polycarbonate homopolymer; and (d) 12.0 wt% to less than 20.0 wt% of glass fiber; wherein the polycarbonate homopolymer is bromine - free.

2. The composition according to claim 1, wherein, based on the total weight of the composition: (a) The poly(carbonate - siloxane) copolymer is present in an amount of 30.0 wt% - 50.0 wt%, preferably 35.0 wt% - 45.0 wt%; (b) The brominated polycarbonate is present in an amount of 25.0 wt% - 39.0 wt%, preferably 30.0 wt% - 39.0 wt%; and (c) The polycarbonate homopolymer is present in an amount of 8.0 wt% - 18.0 wt%.

3. The composition according to any one of claims 1 - 2, wherein the poly(carbonate - siloxane) copolymer has a silicon content of less than 3.0 wt%, preferably less than 1.5 wt%, and preferably the silicon content is 1.0 wt%, based on the total weight of the poly(carbonate - siloxane) copolymer.

4. The composition according to any one of claims 1 - 3, wherein the glass fiber is present in an amount of 12.0 wt% - 20.0 wt%, preferably 12.0 wt% - 18.0 wt%, based on the total weight of the composition; and the polycarbonate homopolymer is present in an amount of 10.0 wt% - 18.0 wt%, preferably 12.0 wt% - 18.0 wt%, based on the total weight of the composition.

5. The composition according to any one of claims 1 - 4, wherein the composition comprises or consists of, based on the total weight of the composition: (a) 30.0 wt% - 50.0 wt% of at least one poly(carbonate - siloxane) copolymer; (b) 25.0 wt% - 39.0 wt% of at least one brominated polycarbonate; (c) 10.0 wt% - 18.0 wt% of at least one polycarbonate homopolymer; and (d) 12.0 wt% to less than 18.0 wt% of glass fiber; wherein the polycarbonate homopolymer is bromine - free.

6. The composition according to any one of claims 1 - 4, wherein the composition comprises or consists of, based on the total weight of the composition: (a) 35.0 wt% - 45.0 wt% of at least one poly(carbonate - siloxane) copolymer; (b) 30.0 wt% - 39.0 wt% of at least one brominated polycarbonate; (c) 10.0 wt% - 18.0 wt% of at least one polycarbonate homopolymer; and (d) 12.0 wt% to less than 18.0 wt% of glass fiber; wherein the polycarbonate homopolymer is bromine - free.

7. The composition according to any one of claims 1-6, wherein the polycarbonate homopolymer is selected from linear polycarbonate homopolymers, branched polycarbonate homopolymers, and combinations thereof.

8. The composition according to any one of claims 1-7, wherein the polycarbonate homopolymer is a linear polycarbonate homopolymer comprising or consisting of aromatic carbonate repeating units of the formula: wherein R a and R b each independently is C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl or C 1-12 alkoxy, p and q each independently are integers from 0 - 4, and X a is a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, the group of formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d each independently are hydrogen or C 1-10 alkyl, or the group of formula —C(═R e )—, wherein R e is a divalent C 1-10 hydrocarbyl group, preferably X a is the group of formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d each independently are C 1-6 alkyl.

9. The composition according to claim 8, wherein the linear polycarbonate homopolymer comprises or consists of repeating units derived from bisphenol A carbonate.

10. The composition according to any one of claims 1-9, wherein the poly(carbonate-siloxane) copolymer comprises or consists of repeating units derived from: (i) aromatic carbonate units of the formula: wherein R a and R b each independently is C 1-12 alkyl, C 1-12 alkenyl, C 3-8 cycloalkyl or C 1-12 alkoxy, p and q each independently are integers from 0 - 4, and X a is a single bond, —O—, —S—, —S(O)—, —S(O)2—, —C(O)—, the group of formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d each independently are hydrogen or C 1-10 alkyl, or a group of formula —C(═R e )—, wherein R e is a divalent C 1-10 hydrocarbyl group, preferably wherein X a is the group of formula —C(R c )(R d )— C 1-11 alkylene, wherein R c and R d each independently are C 1-6 alkyl, preferably wherein said aromatic carbonate unit is derived from bisphenol A carbonate; and (ii) siloxane units selected from the formula: and any combination thereof, wherein 'E' has an average value of 2.0 - 200.

0.

11. The composition according to any one of claims 1-10, wherein the brominated polycarbonate comprises repeating units derived from: (i) brominated aromatic carbonate repeating units derived from 2,2',6,6'-tetrabromo-4,4'-isopropylidenediphenol; and (ii) aromatic carbonate repeating units derived from bisphenol A.

12. The composition according to any one of claims 1-11, wherein the composition comprises less than 0.5 wt% of additional flame retardant compounds based on the total weight of the composition, preferably wherein the additional flame retardant compounds are selected from organophosphates / salts, polyetherimide (PEI), polyphenylene ether (PPE), aromatic organophosphorus compounds having two or more phosphorus-containing groups, organic compounds containing phosphorus-nitrogen bonds, halogenated flame retardants, inorganic flame retardants, and combinations thereof.

13. The composition according to any one of claims 1-12, wherein the composition has or is selected to have the following: · Smoke density (Ds4) after 4 minutes less than or equal to 300.0, determined according to ISO 5659-2 on a 3.0 mm thick panel at 50.0 kW / m 2 ; · Smoke density (VOF4) less than or equal to 600.0 measured on a 3.0 mm thick panel at 50.0 kW / m² in accordance with ISO 5659-2 2 ; · Maximum Average Heat Release (MAHRE) measured in accordance with ISO 5660-1 on a 3.0 mm thick panel at less than or equal to 50 kW / m 2 and less than or equal to 90.0 kW / m 2 ; and · Critical heat flux at extinction (CFE) greater than or equal to 20.0 kW / m as measured according to ISO 5658-2 2 ​ 14. An article comprising the composition according to any one of claims 1-12, preferably wherein the article is suitable for use in a mass transportation system, preferably wherein the article is at least one of a railway component, an aerospace component, or an automotive component. Use of the composition according to any one of claims 1-12 for improving the flame retardant properties of articles used in a mass transportation system.

Images