WO2025238239A1

WO2025238239A1 - Thermoplastic composition

Info

Publication number: WO2025238239A1
Application number: PCT/EP2025/063603
Authority: WO
Inventors: Jiawei REN; Ying XI; Kevin DI; Qiang Fu; Gang Wang; Tongmin CUI; Sijun LI; Yu Ding
Original assignee: SABIC Global Technologies BV
Current assignee: SABIC Global Technologies BV
Priority date: 2024-05-16
Filing date: 2025-05-16
Publication date: 2025-11-20
Anticipated expiration: 2026-11-16

Abstract

The invention relates to a thermoplastic composition comprising, based on the weight of the composition: A) at least 90.0 wt.% of polycarbonate, B) from 0.01 – 1.0 wt.% of at least one flame retardant additive selected from the group consisting of potassium perfluorobutane sulfonate, sodium toluene-sulfonate and potassium diphenyl sulfone sulfonate, C) from 2.0 – 6.0 wt.% of a masterbatch containing C1) one or more copolymers containing structural units derived from an olefin and structural units derived from a polar comonomer, C2) a vulcanized silicone elastomer, D) from 0.0 – 3.0 wt.% of further components wherein the sum of the components A) - D) is 100 wt.%, wherein the content of polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer in the thermoplastic composition is less than 0.3 wt% with respect to the total thermoplastic composition.

Description

THERMOPLASTIC COMPOSITION

The present invention relates to a thermoplastic composition. The invention further relates to articles comprising or consisting such composition such as automotive articles.

Noise reduction is an important issue for the automotive industry. When two materials slide over each other, "squeaking" sound may be heard. Such sounds are not always desirable and accordingly the industry has developed several approaches. One solution is to apply coatings, but this has a disadvantage that it is time-consuming and expensive.

Flame retardancy is also an important property for automotive applications of polycarbonate compositions, for example an infotainment panel or electronics screen framework.

It is an objective of the present invention to provide a thermoplastic composition having a combination of good anti-squeak property and good flame retardancy.

Accordingly, the invention provides a thermoplastic composition comprising, based on the weight of the composition:

A) at least 90.0 wt.% of polycarbonate,

B) from 0.01 - 1.0 wt.% of at least one flame retardant additive selected from the group consisting of potassium perfluorobutane sulfonate, sodium toluene-sulfonate and potassium diphenyl sulfone sulfonate,

C) from 2.0 - 6.0 wt.% of a masterbatch containing

C1) one or more copolymers containing structural units derived from an olefin and structural units derived from a polar comonomer,

C2) a vulcanized silicone elastomer,

D) from 0.0 - 3.0 wt.% of further components, wherein the sum of the components A) - D) is 100 wt.%, wherein the content of polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer in the thermoplastic composition is less than 0.3 wt% with respect to the total thermoplastic composition. The invention further provides a thermoplastic composition comprising, based on the weight of the composition:

A) at least 90.0 wt.% of polycarbonate,

C) from 2.0 - 6.0 wt.% of a masterbatch containing

C1) one or more copolymers containing structural units derived from an olefin and structural units derived from a polar comonomer, wherein the polar comonomer is represented by CH₂=CR¹C(=O)OR² or CH₂=CR³OC(=O)R⁴ wherein R¹, R², R³, R⁴ is individually selected from H and C1-C8 linear or branched alkyl, C2) a vulcanized silicone elastomer,

D) from 0.0 - 3.0 wt.% of further components, wherein the sum of the components A) - D) is 100 wt.%, wherein the content of polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer in the thermoplastic composition is less than 0.3 wt% with respect to the total thermoplastic composition.

It was surprisingly observed that the type of flame retardant additive heavily influenced the anti-squeak property of the composition and that the flame retardant additive used according to the invention resulted in a thermoplastic composition having a combination of good anti-squeak property and good flame retardancy.

It was further surprisingly observed that the (substantial) absence of polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer in the thermoplastic composition leads to good flame retardancy.

It is noted that US2023/220196 discloses use of a commercially available anti-squeak agent HMB1903 in a polycarbonate blend comprising PC/ABS. HMB1903 is known for use only for improving anti-squeak property of a PC/ABS composition and is sold as such.

CN117402477 discloses a flame-retardant polycarbonate material comprising polycarbonate resin, modified silicone rubber, sulfonate flame retardant, anti-drip agent, and optional processing aid. CN 117402477 discloses that PE-GMA is used for coating the silicone rubber and vulcanization reaction of the silicone rubber and the PE- GMA is used. A) polycarbonate

The thermoplastic composition according to the invention comprises polycarbonate. The amount of polycarbonate in the thermoplastic composition is at least 90.0 wt%, for example 90.0 to 97.5 wt% or 93.0 to 97.0 wt%.

Polycarbonate and its production methods are per se well-known and is further described in detail e.g. in WO2014130751 , [0037]-[0082], incorporated herein by reference.

The polycarbonate in the polycarbonate composition can be one type of polycarbonate or a mixture of at least two polycarbonates which each may be a homopolymer or a copolymer. It is preferred that the polycarbonate is a polycarbonate homopolymer obtained by reacting a bisphenol, such as bisphenol A, with a carbonate source such as phosgene or a diarylcarbonate such as diphenyl carbonate. Accordingly the polycarbonate of the composition according to the invention may be prepared using the so called interfacial process, wherein BPA reacts with phosgene, or may be prepared by means of the so-called melt or direct transesterification process, wherein BPA reacts with diphenyl carbonate. These two types of polycarbonate are known to the skilled person and may be further referred to herein as interfacial polycarbonate and melt polycarbonate. The skilled person knows that these two types of polycarbonate differ in amount of Fries branching, which only exists in melt polycarbonate and further in the terminal hydroxyl content, which is typically much lower for interfacial polycarbonate.

In some preferred embodiments, the polycarbonate is an interfacial polycarbonate, i.e. a polycarbonate obtained via the interfacial process. The interfacial process typically provides polycarbonate with a low number of hydroxyl chain ends compared to the melt process. A low amount of hydroxyl chain ends is advantageous for heat stability and color retention of the polycarbonate.

In other preferred embodiments, the polycarbonate is a melt polycarbonate, i.e. a polycarbonate obtained via the melt process.

In some embodiments, the polycarbonate is a mixture of at least one polycarbonate obtained via the interfacial process and at least one polycarbonate obtained with the melt process. In such an embodiment the amount of melt polycarbonate may be from 30 - 70 wt.% and the amount of interfacial polycarbonate from 70 - 30 wt.%, based on the combined weight of the melt polycarbonate and the interfacial polycarbonate.

The polycarbonate may comprise or consist of interfacial polycarbonate. It is preferred that the interfacial polycarbonate is prepared by reacting bisphenol A and phosgene. Accordingly it is preferred that the polycarbonate is a bisphenol A polycarbonate or a bisphenol A polycarbonate homopolymer.

Preferably, the polycarbonate, or mixture of polycarbonates, has a melt flow rate according to ISO1133-1 :2011 at 300 °C and 1.2 kg of from 3.0 to 35 g/10min, preferably from 6.0 to 25 g/10min, more preferably from 14 to 21 g/10min.

In some preferred embodiments, the thermoplastic composition comprises a first polycarbonate having a melt flow rate according to ISO1133-1:2011 at 300 °C and 1.2 kg of 3.0 to 15 g/10min and a second polycarbonate having a melt flow rate according to ISO1133-1 :2011 at 300 °C and 1.2 kg of 20 to 35 g/10min.

A specific example of polycarbonate in the thermoplastic composition is a mixture consisting of bisphenol A polycarbonate homopolymer and a polycarbonatepolysiloxane copolymer.

In some embodiments, the polycarbonate comprises post-consumer recycled (PCR) polycarbonate or post-industrial recycled (PIR) polycarbonate.

B) flame retardant additive

The thermoplastic composition according to the invention comprises a flame retardant additive selected from the group consisting of potassium perfluorobutane sulfonate, sodium toluene-sulfonate and potassium diphenyl sulfone sulfonate. The amount of such flame retardant additive is from 0.01 to 1.0 wt.%, for example 0.02 to 0.50 wt%. Preferably, the flame retardant additive comprises or is potassium perfluorobutane sulfonate.

The thermoplastic composition according to the invention preferably does not contain other types of flame retardant additives, in particular does not contain bisphenol A bis(diphenyl phosphate).

C) masterbatch The thermoplastic composition according to the invention comprises a masterbatch solid at room temperature containing

C1) one or more copolymers containing structural units derived from an olefin and structural units derived from a polar comonomer, C2) a vulcanized silicone elastomer.

The masterbatch C) used in the composition according to the invention may be those described in detail in US20230220196, [0120]-[0218] as follows:

A masterbatch is an additive for polymers to endow these with certain properties. An additive as the actual active ingredient is encapsulated at high concentration in a carrier resin at elevated temperature. Cooling of the carrier resin is typically followed by pelletization to obtain and easily meterable form. This allows additives which may be liquid and therefore difficult to introduce into a polymer alone to be admixed easily.

In component C, component C1 is this carrier resin. Component C1 is a copolymer containing structural units derived from an olefin and structural units derived from a polar comonomer. Suitable olefins include in particular ethylene and propylene and particularly preferred comonomers are acrylic acid, methacrylic acid and vinyl acetate. Further preferred comonomers are methyl acrylate, ethyl acrylate, 2-chloroethyl vinyl ether, 2-ethylhexyl acrylate, butyl acrylate and trimethylolpropane triacrylate. It is also possible to employ mixtures of such polyolefin copolymers.

In preferred embodiments, the polar comonomer in C1) is represented by CH₂=CR¹C(=O)OR² or CH₂=CR³OC(=O)R⁴ wherein R¹, R², R³, R⁴ is individually selected from H and C1-C8 linear or branched alkyl. Preferably, the polar comonomer in C1) is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic acid, methacrylic acid and vinyl acetate. Preferably, the polar comonomer in C1) is selected from the group consisting of acrylic acid, methacrylic acid and vinyl acetate.

In preferred embodiments, the masterbatch contains as C1) one or more copolymers containing structural units derived from an olefin and structural units derived from a polar comonomer, wherein the olefin is selected from ethylene and propylene and the polar comonomer is the polar comonomer in C1) is represented by CH₂=CR¹C(=O)OR² or CH₂=CR³OC(=O)R⁴ wherein R¹, R², R³, R⁴ is individually selected from H and C1-C8 linear or branched alkyl. A particularly suitable carrier resin (C1) is Elvaloy™ AC 1609 (Dupont), which is an ethylene acrylate copolymer.

The proportion of component C1 is 40 to 80% by weight based on component C.

A polysiloxane contains a plurality of Si — O — Si bonds which form a polymer chain, wherein the backbone of the polymer chain consists of — (Si — O) — repeating units.

An organopolysiloxane contains repeating (Si — O) units where at least one Si atom carries at least one organic group, i.e. group containing at least one carbon atom.

A silane is a compound derived from Si — H4 and often contains at least one Si — C bond. Unless otherwise stated a silane contains only one Si atom.

A polysiloxane comprises end groups and side groups. An end group is a chemical group attached to a Si atom located at one end of the polymer chain. A side group is a group attached to a Si atom, wherein the Si atom is not located at the end of the chain.

An organopolysiloxane typically contains a mixture of the following structures:

(iv)

(M)

(D)

(T)

(Q) wherein M, D, T and Q independently of one another represent the functionality of structural groups of organopolysiloxane. In particular, M represents a monofunctional group RaSiOi/2; D represents a difunctional group R2SiO2/2 ; T represents a trifunctional group RSiC>3/2; and Q represents a tetrafunctional group SiC>4/2. Thus for example linear organopolysiloxanes have a backbone of D units and the end groups are M units while branched organopolysiloxanes may have for example a backbone of D units interspersed with T and/or Q units.

A crosslinking reaction is a reaction in which two or more molecules, wherein at least one of the molecules is a polymer, are joined together to cure the polymer.

A crosslinker is a compound capable of bringing about a crosslinking reaction of a polymer. The process of mixing the elastomer and thermoplastic matrix and curing the elastomer using a crosslinker (or catalyst) during the mixing process is known as dynamic vulcanization. The resulting blend consisting of a thermoplastic matrix and a crosslinked (vulcanized) elastomer is referred to as a thermoplastic vulcanizate. When the crosslinked (vulcanized) elastomeric component is a silicone polymer while the thermoplastic component is an organic non-silicone polymer this is referred to as a thermoplastic silicone vulcanizate.

The vulcanized silicone elastomer (C2) may be produced by curing any of the following compositions: a diorganopolysiloxane having on average at least two alkenyl groups per molecule (C2a1) and either

(i) an organopolysiloxane having at least two Si-bonded hydrogen atoms, alternatively at least three Si-bonded hydrogen atoms, per molecule (C2a2) and a hydrosilylation catalyst (C2a3) and optionally a catalyst inhibitor (C2a5) or

(ii) a free-radical initiator (C2a4).

Alternatively, the vulcanized silicone elastomer (C2) may be produced by curing a composition comprising a silanol-terminated diorganopolysiloxane (C2b1), organopolysiloxane having at least two Si-bonded hydrogen atoms, alternatively at least three Si-bonded hydrogen atoms, per molecule (C2a2) and a condensation catalyst (C2b3).

The proportion of component C2 is preferably 20% to 60% by weight based on component C.

Diorganopolysiloxane Having on Average at Least Two Alkenyl Groups Per Molecule (C2a1) The silicon-bonded organic groups of component (C2a1) are independently of one another selected from hydrocarbon or halogenated hydrocarbon groups.

This may be selected for example from alkyl groups having 1 to 20 carbon atoms such as methyl, ethyl, propyl, butyl, pentyl and hexyl; cycloalkyl groups such as cyclohexyl and cycloheptyl; alkenyl groups having 2 to 20 carbon atoms such as vinyl, allyl and hexenyl; aryl groups having 6 to 12 carbon atoms such as phenyl, tolyl and xylyl; aralkyl groups having 7 to 20 carbon atoms such as benzyl and phenethyl and halogenated alkyl groups having 1 to 20 carbon atoms such as 3,3,3-trifluoropropyl and chloromethyl.

These groups are selected such that the diorganopolysiloxane has a glass transition temperature (or melting point) below room temperature, thus causing this component to form an elastomer upon curing.

It is preferable when the at least 85 mol %, more preferably at least 90 mol %, of the silicon-bonded organic groups in component (C2a1) are methyl groups.

Polydiorganosiloxane (C2a1) may accordingly be a homopolymer, a copolymer, or a terpolymer containing such organic groups. Examples include silicone liquids or silicone rubbers comprising dimethylsiloxy units, dimethylsiloxy units and phenylmethylsiloxy units; dimethylsiloxy units and diphenylsiloxy units; and dimethylsiloxy units, diphenylsiloxy units and phenylmethylsiloxy units, among others. Molecular structure is likewise not critical and linear and/or partially branched structures may be concerned, wherein linear dimethylsiloxy units are preferred. Examples include a,w-vinyldimethylsiloxypolydimethylsiloxane, an a,w- vinyldimethylsiloxy copolymer of methylvinylsiloxane and dimethylsiloxane units, and/or an a,w-trimethylsiloxy copolymer of methylvinylsiloxane and dimethylsiloxane units.

The diorganopolysiloxane polymer (C2a1) may have a viscosity of at least 100 000 mm²s^-1(cSt) at 25° C. but typically at least 1 000 000 mm²-s'¹ (cSt) at 25° C. measured using an AR 2000 Rheometer from TA Instruments, New Castle, Del., USA or a suitable Brookfield viscometer fitted with the most suitable spindle for the viscosity to be measured. The diorganopolysiloxane polymer (C2a1) may be an uncured silicone rubber characterized by a Williams plasticity value of at least 100 mm/100 measured according to ASTM D-926-08 using a Williams parallel plate plastometer. An alternative to the use of Williams plasticity the rubber may also be evaluated by its shore A hardness according to ASTM D2240-03, wherein the values are typically at least 30. The diorganopolysiloxane polymer (C2a1) may be modified with a small amount of a non-reactive silicone such as a trimethylsilyl-terminated polydimethylsiloxane. In one alternative the diorganopolysiloxane polymer (C2a1) is an unvulcanized silicone rubber.

Organopolysiloxane Having at Least Two Si-Bonded Hydrogen Atoms, Alternatively at Least Three Si-Bonded Hydrogen Atoms, Per Molecule (C2a2)

The organopolysiloxane having at least two Si-bonded hydrogen atoms, alternatively at least three Si-bonded hydrogen atoms, per molecule (C2a2) may be for example an organosilicon resin having a low molecular weight or a short- or long-chain organosiloxane polymer, which may be linear or cyclic. The silicon-bonded organic groups of component (C2a2) are independently of one another selected from any of the hydrocarbon or halogenated hydrocarbon groups described above in connection with diorganopolysiloxane (C2a1 and C2b1) including preferred embodiments thereof. The molecular structure of component (C2a2) is likewise not critical and linear, partially branched, cyclic and network structures are possible, wherein linear polymers or copolymers are preferred, and this component should be effective in the curing of components (C2a1) and (C2b1).

(C2a2) preferably has at least three silicon-bonded hydrogen atoms per molecule that are capable of reacting with the alkenyl or other aliphatically unsaturated groups of the diorganopolysiloxane polymer (C2a1) and the — OH groups of (C2b1). The position of the silicon-bonded hydrogen in component (C2a2) is not critical, i.e. the Si — H groups may be terminal groups or side groups in non-terminal positions along the molecular chain or at both positions. To ensure crosslinking when (C2a2) has only two Si — H bonds at least a portion of the respective polymer (C2a1) or (C2b1) must have at least three groups capable of reacting with (C2a2) molecules. The organopolysiloxane having at least two Si-bonded hydrogen atoms, alternatively at least three Si-bonded hydrogen atoms, per molecule (C2a2), may have for example the general formula:

R³R⁴ ₂SIO (R⁴ ₂SiO)^(R⁴HSiO)_gSiR⁴ ₂R³ or

(V) 4⁴ wherein R⁴ presents an alkyl or aryl group having up to 10 carbon atoms and R³ represents a group R⁴ or a hydrogen atom, p has a value of 0 to 20 and q has a value of 1 to 70 and wherein at least 2 or 3 silicon-bonded hydrogen atoms are present per molecule. R⁴ may be for example a lower alkyl group having 1 to 3 carbon atoms, for example a methyl group. The organopolysiloxane having at least two Si-bonded hydrogen atoms, alternatively at least three Si-bonded hydrogen atoms, per molecule (C2a2) may have a viscosity of 0.5 to 1000 mm² s^-1 (cSt), preferably 2 to 100 mm² s^-1(cSt) more preferably 5 to 60 mm² s^-1 (cSt), at 25° C. for example, typically measured with a Brookfield viscometer fitted with the most suitable spindle for the viscosity to be measured. The average degree of polymerization of (C2a2) may for example be in the range from 30 to 400 siloxane units per molecule.

Component (C2a2) may be elucidated by the following siloxanes which typically have a viscosity of 0.5 to 1000 mm² s^-1 (cSt) at 25° C.: low molecular weight siloxanes, such as PhSi(OSiMe2H)3; trimethylsiloxy-endblocked methylhydridopolysiloxanes; trimethylsiloxy-endblocked dimethylsiloxane-methylhydridosiloxane copolymers; dimethylhydridosiloxy-endblocked dimethylpolysiloxanes; dimethylhydrosiloxy-endblocked methylhydropolysiloxanes; dimethylhydridosiloxy-endblocked dimethylsiloxane-methylhydridosiloxane copolymers; cyclic methylhydropolysiloxanes; cyclic dimethylsiloxane-methylhydridosiloxane copolymers; tetrakis(dimethylhydrosiloxy)silane; silicone resins consisting of (CH3)2HSiOi/2, (CH3)3SiOi/2 and SiC>4/2 units; and silicone resins consisting of (CH3)2HSiOi/2, (CH3)3SiOi/2 CHsSiCh^, PhSiC>3/2 and SiC>4/2 units.

(C2a2) may comprise a mixture of more than one of these materials.

The molar ratio of Si — H groups in (C2a2) to aliphatically unsaturated groups in the diorganopolysiloxane polymer (C2a1) is preferably at least 1 :1 and may be up to 8:1 or 10:1. The molar ratio of Si — H groups to aliphatically unsaturated groups is preferably in the range from 1 .5: 1 to 5: 1.

(C2a2) is used in an amount such that the molar ratio of Si — H therein to Si — OH in component (C2b1) is about 0.5 to 10, preferably 1 to 5 and most preferably about 1.5. These Si — H functional materials are well known in the art and many are commercially available.

Hydrosilylation Catalyst (C2a3)

The hydrosilylation catalyst (C2a3) is preferably a platinum group metal (platinum, ruthenium, osmium, rhodium, iridium and palladium) or a compound thereof.

Preferred catalysts include platinum and/or platinum compounds, for example finely powdered platinum; a chloroplatinic acid or an alcohol solution of a chloroplatinic acid; an olefin complex of a chloroplatinic acid; a complex of a chloroplatinic acid and an alkenylsiloxane; a platinum-diketone complex; metallic platinum on silicon dioxide, aluminum dioxide, carbon or a similar support; or a thermoplastic resin powder containing a platinum compound.

The catalyst (C2a3) is preferably used in an amount of 0.5 to 100 ppm (by weight) of platinum group metal based on the polyorganosiloxane composition (C), more preferably 1 to 50 ppm. The hydrosilylation catalyst (C2a3) catalyzes the reaction of the alkenyl groups of the diorganopolysiloxane polymer (C2a1) with the Si — H groups of (C2a2).

Inhibitor (C2a5)

If a hydrosilylation catalyst is used for curing the diorganopolysiloxane polymer (C2a1) the composition may optionally contain an inhibitor (C2a5) to retard the curing process. The term “inhibitor” is herein to be understood as meaning a material which retards the curing of component component (C2a1) when incorporated in small amounts, such as for example less than 10 percent by weight based on the siloxane composition of (C2a1), without affecting the overall curing of the mixture.

Inhibitors of platinum group-based catalysts (C2a5), in particular platinum-based catalysts (C2a5), are known. These include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, nitriles and diaziridines.

The inhibitor (C2a5) is preferably selected from the group consisting of 1-ethynyl-1- cyclohexanol, 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 2- phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2- propynol and mixtures thereof.

The inhibitor (C2a5) may be added in an amount in the range from 0% to 10% by weight based on component (C2), preferably 0.05% to 5% by weight of component (C2), but is generally used in an amount sufficient to retard the curing of the diorganopolysiloxane (C2a1). This amount may be optimized for a particular system by routine experimentation.

Radical Initiator (C2a4)

The radical initiator (C2a4) is a compound that decomposes at elevated temperature to form free-radical species. The latter promote the crosslinking reaction between the alkenyl groups of diorganopolysiloxanes (C2a1) during the dynamic vulcanization step of the present process. This component is selected for example from azo compounds, carbon compounds and organic peroxy compounds such as hydroperoxides, diacyl peroxides, ketone peroxides, peroxy esters, dialkyl peroxides, diaryl peroxides, arylalkyl peroxides, peroxydicarbonates, peroxyketals, peroxyacids, acylalkyls and alkyl monoperoxydicarbonates.

For the purposes of the present invention the radical initiator (C2a4) is selected such that the difference between the 6 minute half-life of the initiator and the process temperature is between -60° C. and 20° C. The following condition is met: -60° C <{T(6)-T(0)}<20° C., wherein T(6) represents the temperature (° C.) at which the initiator has a half-life of 6 minutes and T(0) represents the processing temperature (° C.) before initiator addition (i.e. the actual temperature of the mixture of components (C1) to (C2)). The value of T(6) is available from the manufacturer of the initiator or may be determined by methods known in the art. After introduction of the initiator the temperature generally rises slightly as dynamic vulcanization occurs unless intentional cooling is carried out. However, such cooling is generally unnecessary unless the temperature rises dramatically (for example more than about 30° C.).

Examples of suitable radical initiators include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2- methylbutyronitrile), dibenzoyl peroxide, tert-amyl peroxyacetate, 1 ,4-di(2-tert- butylperoxyisopropyl)benzene, tert-butylcumyl peroxide, 2,4,4-trimethylpentyl-2- hydroperoxide, diisopropylbenzene monohydroperoxide, cumyl hydroperoxide, tertbutyl hydroperoxide, tert-amyl hydroperoxide, 1,1-di(tert-butylperoxy)cyclohexane, tertbutylperoxycyclohexane, tert-butylperoxyperoxybenzoate, dicumyl peroxide, 2,5- dimethyl-2,5-di-tert-butylperoxyhexanebis(1-methyl-1-phenylethyl)peroxide, 2,5- dimethyl-2,5-di-(tert-butylperoxy)-3-hexyne, di-tert-butyl peroxide, a,a- dimethylbenzylhydroperoxide and 3,4-dimethyl-3,4-diphenylhexane.

The initiator (C2a4) is used in an amount sufficient to cure the diorganopolysiloxane (C2a1) and this amount is optimized for a particular system by routine experimentation.

An insufficient amount results in insufficient crosslinking and poor mechanical properties. On the other hand, addition of excess initiator results in uneconomic and undesired side reactions such as polymer degradation. The initiator (C2a4) is preferably added in an amount of 0.05 to 6 parts by weight, alternatively 0.2 to 3 parts by weight, per 100 parts by weight of diorganopolysiloxane (C2a1).

Diorganopolysiloxane (C2b1)

The diorganopolysiloxane (C2b1) is a silicone liquid or a silicon rubber in each case terminated with silanol (i.e. — SiOH) group and has a viscosity of at least 100 000 mm²s"¹(cSt) at 25° C., preferably at least 1 000 000 mm²s"¹(cSt) at 25° C. The silicon- bonded organic groups of component (C2b1) are independently of one another selected from hydrocarbon or halogenated hydrocarbon groups as defined hereinabove for (C2a1). Again, methyl preferably accounts for at least 85 mol %, more preferably at least 90 mol %, of the silicon-bonded organic groups in component (C2b1).

Polydiorganosiloxane (C2b1) may accordingly be a homopolymer, a copolymer, or a terpolymer containing such organic groups. Examples include silicone liquids or silicone rubbers comprising dimethylsiloxy units and phenylmethylsiloxy units; dimethylsiloxy units and diphenylsiloxy units; and dimethylsiloxy units, diphenylsiloxy units and phenylmethylsiloxy units, among others. Molecular structure is likewise not critical and may comprise linear or partially branched structures, wherein linear structures are preferred.

Specific examples of organopolysiloxane (C2b1) include: dimethylhydroxysiloxy- endblocked dimethylsiloxane homopolymers; dimethylhydroxysiloxy-endblocked methylphenylsiloxane-dimethylsiloxane copolymers and dimethylhydroxysiloxy- endblocked methylphenylpolysiloxanes. Preferred systems for low temperature applications include silanol-functional methylphenylsiloxanedimethylsiloxane copolymers and diphenylsiloxane-dimethylsiloxane copolymers, wherein the preferred mole content of dimethylsiloxane units is about 93%. Component (C2b1) may also consist of combinations of two or more organopolysiloxane liquids or rubbers. Component (C2b1) is most preferably a polydimethylsiloxane homopolymer terminated with a silanol group at each end of the molecule.

The molecular weight of the diorganopolysiloxane is preferably sufficient to impart a Williams plasticity number of at least about 30 as determined by ASTM D-926-08. The plasticity number, as used herein, is defined as the thickness in millimeters* 100 of a cylindrical test specimen having a volume of 2 cm³ and a height of approximately 10 mm after subjecting the specimen to a compressive load of 49 Newtons at 25° C. for three minutes. Although there is no absolute upper limit for the plasticity of (C2b1), processability in conventional mixing equipment generally limits this value. The plasticity number should preferably be about 100 to 200, most preferably about 120 to 185. Such uncrosslinked silicone rubbers may easily be dispersed in the one or more thermoplastic organic materials (C1) without the need for a filler (C2c).

However, it has been found that liquid diorganopolysiloxanes having a viscosity of about 10 to 100 Pa-s at 25° C. often cannot be readily dispersed in further thermoplastic resin. In these circumstances the liquid must be mixed with up to about 300 parts by weight of filler (C2c), as described below, per 100 parts by weight (C2b1) to facilitate dispersion. The liquid and the filler are preferably mixed before adding to this combination to additional thermoplastic resin, though they may also be added separately.

Condensation Catalyst (C2b3)

The condensation catalyst (C2b3) of the present invention is any desired compound that promotes the condensation reaction between the Si — OH groups of diorganopolysiloxane (C2b1) and the Si — H groups of the organopolysiloxane having at least two Si-bonded hydrogen atoms, preferably at least three Si-bonded hydrogen atoms, per molecule (C2a2) to cure the diorganopolysiloxane by forming — Si — O — Si — bonds. However, the catalyst (C2b3) cannot be a platinum compound or a complex since the use of such a condensation catalyst often results in poor processing and poor physical properties of the resulting thermoplastic silicone vulcanizate. The condensation catalyst (C2b3) is present in an amount sufficient to cure the diorganopolysiloxane (C2b1) and the organopolysiloxane having at least two, preferably at least three, Si-bonded hydrogen atoms (C2a2) as defined above.

Examples of suitable catalysts include metal carboxylates such as dibutyltin diacetate, dibutyltin dilaurate, tin tripropyl acetate, tin octoate, tin oxalate, tin naphthanate; amines such as triethylamine, ethylene triamine; and quaternary ammonium compounds such as benzylttrimethylammonium hydroxide, beta-hydroxyethyltrimethylammonium 2- ethythexanoate and beta-hydroxyethylbenzyltrimethyldimethylammonium butoxide (see for example U.S. Pat. No. 3,024,210).

Optional Reinforcing Filler (C2c)

The composition used to produce the vulcanized silicone elastomer may contain a reinforcing filler (C2c). The reinforcing filler (C2c) may be silicon dioxide for example. The silicon dioxide may be, for example, pyrogenic silicon dioxide, for example that marketed by Cabot under the trade name Cab-O-Sil MS-75D, or may be precipitated silicon dioxide. The particle size of the silica is for example in the range from 0.5 m to 20 m, preferably from 1 to 10 m. The silicon dioxide may be a surface-treated silicon dioxide. The surface treatment can be carried out for example with a silane or with a polysiloxane. The silane or polysiloxane used for treatment of the silicon dioxide typically contains hydrophilic groups which bond to the silicon dioxide surface and aliphatically unsaturated hydrocarbon or hydrocarbonoxy groups and/or Si-bonded hydrogen atoms.

For example, the silicon dioxide may be treated with 2% to 60% by weight, based on the silica, of an alkoxysilane containing alkenyl groups or an oligomeric organopolysiloxane containing alkenyl groups.

Preferably, the vulcanized silicone elastomer is not grafted with the one or more copolymers.

The process for producing the masterbatch (C) can comprise the steps of:

(i) mixing components used to produce the vulcanized silicone elastomer (C2) to form a silicone composition and vulcanizing the silicone composition to form the vulcanized silicone elastomer (C2) and

(ii) mixing the vulcanized silicone elastomer (C2) with component (C1). The process for producing the masterbatch (C) can comprise the steps of:

(i) mixing components used to produce the vulcanized silicone elastomer (C2) to form a silicone composition,

(ii) mixing the silicone composition with component (C1),

(iii) vulcanizing the silicone composition to form the vulcanized silicone elastomer (C2).

The masterbatch may also be produced by the following procedure, wherein the sequence of the steps may also be varied:

1. The one or more thermoplastic organic materials (C1) are first softened or melted as required at a suitable temperature.

2. The components of (C2) involved in the dynamic vulcanization of the diorganopolysiloxane (C2a1) or (C2b1) to form the proportion of the vulcanized silicone elastomer portion in the masterbatch composition are then incorporated into the one or more thermoplastic organic materials (C1) at elevated temperature.

Several alternatives may be used for the processes described above.

The performance of the recited step is carried out in such a way as to allow heating and commixing of the constituents. Component (C1) must be softened. Temperatures between 185° C. and 310° C. are suitable therefor.

The mixing can be achieved, for example, by compounding using a single-axis extruder, a dual-axis extruder or a multi-axis extruder. Alternatively, mixing can be performed using for example an internal batch mixer such as a Z-blade mixer or a Banbury mixer, wherein sufficient mixing time must be ensured to achieve a uniform distribution of the components.

The masterbatch may then be pelletized.

The vulcanized silicone elastomer (C2) is produced by dynamic curing of one of the following curing compositions which optionally also contains component (C2c):

1) a diorganopolysiloxane (C2a1) having on average at least two alkenyl groups per molecule and an organopolysiloxane having at least two Si-bonded hydrogen atoms, preferably at least three Si-bonded hydrogen atoms, per molecule (C2a2) and a hydrosilylation catalyst (C2a3) and optionally a catalyst inhibitor (C2a5);

2) a diorganopolysiloxane (C2a1) having on average at least two alkenyl groups per molecule and a radical initiator (C2a4) and optionally organopolysiloxane having at least two Si-bonded hydrogen atoms, preferably at least three Si-bonded hydrogen atoms, per molecule (C2a2); or

3) a silanol-terminated diorganopolysiloxane (C2b1), an organopolysiloxane having at least two Si-bonded hydrogen atoms (C2a2) and a condensation catalyst (C2b3). The diorganopolysiloxane (C2a1) or (C2b1) is metered in and distributed into the softened or melted matrix of the one or more thermoplastic organic materials (C1) with input of mechanical mixing energy.

The ingredients of the alternative curing packages are then metered into the mixture separately (no preferred order) or in combination to initiate and complete vulcanization of the respective polyorganosiloxane.

A hydrosilylation reaction inhibitor (addition curing reaction inhibitor) (C2a5) may be added to the mixture to increase the residence time before completion of the vulcanization reaction in a hydrosilylation (addition) curing process.

If used, the inhibitor (C2a5) is metered into the composition either before the catalyst and/or before the crosslinker.

The optional additives (C2c) may be introduced as required simultaneously or separately and during or after completion of the dynamic curing process.

Instead of introducing each constituent individually as described above it is alternatively possible to introduce predispersed organopolysiloxane compositions into the one or more thermoplastic organic materials (C1) at elevated temperature.

In a further alternative the components of the composition used for producing the vulcanized silicone elastomers may be premixed and cured, so that the ready- vulcanized silicone elastomer is incorporated into the one or more thermoplastic organic materials (C1).

An example of suitable melt mixing equipment is a twin-screw extruder.

Suitable masterbatches and the production thereof are disclosed in

WO 2019/195516 A1. A suitable commercially available product is Dow Corning™ HMB-1903 Masterbatch (Dow Chemical). The amount of such masterbatch is from 2.0 to 6.0 wt%, for example 2.5 to 5.0 wt%, with respect to the thermoplastic composition.

D) Further components

The thermoplastic composition of the present invention may optionally include additives which do not interfere with the previously mentioned desirable properties but enhance other favorable properties.

Optional additives that may be compounded or blended into the composition of the invention in customary amounts include inert inorganic pigments, dyestuffs, lubricants, UV absorbers, UV stabilizers, anti-oxidants, anti-ozonants, stabilizers, stain- proofing agents, anti-static additives, anti-microbial agents, melt viscosity enhancers, impact modifiers, quenchers, processing aids, and the like. The different additives that can be incorporated in the compositions are commonly used and known to one skilled in the art. Illustrative descriptions of such additives may be found in R. Gachter and H. Muller, Plastics Additives Handbook, 6th edition, 2009.

The further components may comprise a mold release agent, which may also be referred to as a lubricant or a plasticizer. Examples include phthalic acid esters such as dioctyl-4,5-epoxy-hexahydrophthalate; tris-(octoxycarbonylethyl)isocyanurate; tristearin; di- or polyfunctional aromatic phosphates such as resorcinol tetraphenyl diphosphate (RDP), the bis(diphenyl)phosphate of hydroquinone and the bis(diphenyl)phosphate of bisphenol-A; poly-alpha-olefins; epoxidized soybean oil; silicones, including silicone oils; esters, for example, fatty acid esters such as alkyl stearyl esters, e.g., methyl stearate; stearyl stearate, pentaerythritol tetrastearate, and the like; mixtures of methyl stearate and hydrophilic and hydrophobic nonionic surfactants comprising polyethylene glycol polymers, polypropylene glycol polymers, and copolymers thereof, e.g., methyl stearate and polyethylene-polypropylene glycol copolymers in a suitable solvent; waxes such as beeswax, montan wax, paraffin wax or the like.

In some preferred embodiments, the mold release agent is poly-alpha-olefin or pentaerythritol tetrastearate or combination thereof. Preferably, the amount of mould release agent is from 0.1 - 1.0 wt.% with respect to the thermoplastic composition.

The thermoplastic composition according to the invention does not comprise or substantially does not comprise polytetrafluoroethylene (PTFE)-encapsulated styrene- acrylonitrile copolymer (TSAN). If present, the content of TSAN in the thermoplastic composition is less than 0.3 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt%, less than 0.005 wt% with respect to the thermoplastic composition. The (substantial) absence of anti-drip agent was found to be beneficial for the improvement of flame retardancy of the thermoplastic composition.

Polytetrafluoroethylene (PTFE)-encapsulated styrene-acrylonitrile copolymer (TSAN) is known as an anti-drip agent. Another known anti-drip agent is polytetrafluoroethylene (PTFE). Preferably, the thermoplastic composition does not comprise or substantially does not comprise TSAN and PTFE. If present, the total content of TSAN and PTFE is preferably less than 0.3 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt%, less than 0.005 wt% with respect to the thermoplastic composition.

Preferably, the thermoplastic composition does not comprise or substantially does not comprise an anti-drip agent. If present, the content of anti-drip agent (the total content of anti-drip agent in case two or more types of anti-drip agent are present) is preferably less than 0.3 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt%, less than 0.005 wt% with respect to the thermoplastic composition.

The amount of the further components is 0.0 to 2.0 wt%, for example 0.1 to 1.0 wt% with respect to the thermoplastic composition.

Preferably, the thermoplastic composition does not comprise or substantially does not comprise acrylonitrile-butadiene-styrene (ABS). If present, the content of ABS in the thermoplastic composition may e.g. be less than 1.0 wt% or less than 0.1 wt% with respect to the thermoplastic composition.

Preferably, the thermoplastic composition does not comprise or substantially does not comprise an impact modifier selected from the group consisting of styrene-butadiene- styrene (SBS), styrene-butadiene (SBR), styrene-ethylene-butadiene-styrene (SEBS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-ethylene-propylene-diene-styrene (AES), styrene-isoprene-styrene (SIS), methyl methacrylate-butadiene (MB) and methyl methacrylate-butadiene-styrene (MBS). If present, the content of the impact modifier in the thermoplastic composition may e.g. be less than 1.0 wt% or less than 0.1 wt% with respect to the thermoplastic composition. Preferably, the thermoplastic composition has a melt flow rate according to ISO1133- 1 :2011 at 300 °C and 1.2 kg of from 3.0 to 35 g/10min, preferably from 6.0 to 25 g/10min, more preferably from 8.0 to 15 g/10min.

Preferably, the composition has or is selected to have a LIL94 rating of at least V2, more preferably at least V1 , more preferably V0, at a sample thickness of 1.5 mm. Preferably, the composition has or is selected to have a LIL94 rating of at least V2, more preferably at least V1 , more preferably V0, at a sample thickness of 0.8 mm.

The invention further provides a process for making the thermoplastic composition according to the invention comprising melt-mixing components A)-D) e.g. in an extruder.

The invention further provides an article comprising or consisting of the thermoplastic composition according to the invention. Preferably, the article is automotive interior or exterior article, in particular a screen bezel, a screen frame or a frame for electronic components, for example an infotainment panel or electronics screen framework.

The article may be obtained by molding the composition of the invention, such as by injection molding. The article may also be obtained by extrusion followed by thermoforming.

It is noted that the invention relates to the subject-matter defined in the independent claims alone or in combination with any possible combinations of features described herein, preferred in particular are those combinations of features that are present in the claims. It will therefore be appreciated that all combinations of features relating to the composition according to the invention; all combinations of features relating to the process according to the invention and all combinations of features relating to the composition according to the invention and features relating to the process according to the invention are described herein.

It is further noted that the term ‘comprising’ does not exclude the presence of other elements. However, it is also to be understood that a description on a product/composition comprising certain components also discloses a product/composition consisting of these components. The product/composition consisting of these components may be advantageous in that it offers a simpler, more economical process for the preparation of the product/composition. Similarly, it is also to be understood that a description on a process comprising certain steps also discloses a process consisting of these steps. The process consisting of these steps may be advantageous in that it offers a simpler, more economical process.

When values are mentioned for a lower limit and an upper limit for a parameter, ranges made by the combinations of the values of the lower limit and the values of the upper limit are also understood to be disclosed.

The invention is now elucidated by way of the following examples, without however being limited thereto.

Compounding and injection moulding:

Compositions of Table 5 were prepared and various properties were measured according to test methods of Table 1. All the ingredients were dry blended for 3-5 minutes in a super-floater. The resins were pre-dried at 100 °C for about 4hrs before extrusion. The blends were added at the throat feeder. Formulations were compounded on a 37mm Toshiba twin-screw. The details of conditions of extrusion and moulding are in Table 2 and Table 3.

Table 1. Testing methods and standards Table 2. Extrusion profile of PC composition

Table 3. Moulding profile of PC composition

Table 4. Raw material details Table 5 summarizes the formulations and test results of PC compositions. The antisqueak performance was tested by a Ziegler Stick-Slip testing machine under two loading force (10N and 40N) at testing speed of 1mm/S. The testing result RPN value reveals the risk to generate noise. Number 1, 2, 3 represents low risk, 4 and 5 means medium risk whereas 6 to 10 indicates high risk.

Table 5. Formulations and key test results of PC composition Comparative composition C1 without the masterbatch HMB-1903shows good flame retardancy, but RPN values are high, indicating medium to high risk of generating noise.

Comparative composition C2 without flame retardant shows good anti-squeak performance, but no rating at LIL94 at 0.8mm and 1.5mm. Comparative composition C3 comprising BPADP as the flame retardant shows good flame retardancy, but RPN values are very high, indicating high risk of generating noise.

Comparative composition C4 comprising rimar salt as the flame retardant and TSAN shows no rating at LIL94 at 0.8mm and 1.5mm.

Inventive composition E1 comprising rimar salt as the flame retardant and free of TSAN shows a combination of good flame retardancy and good anti-squeak performance.

Claims

1 . A thermoplastic composition comprising, based on the weight of the composition:

A) at least 90.0 wt.% of polycarbonate,

C) from 2.0 - 6.0 wt.% of a masterbatch containing

C2) a vulcanized silicone elastomer,

D) from 0.0 - 3.0 wt.% of further components wherein the sum of the components A) - D) is 100 wt.%, wherein the content of polytetrafluoroethylene-encapsulated styrene-acrylonitrile copolymer in the thermoplastic composition is less than 0.3 wt% with respect to the total thermoplastic composition.

2. The thermoplastic composition according to claim 1 , wherein the polar comonomer in C1) is represented by CH2=CR¹C(=O)OR² or CH2=CR³OC(=O)R⁴ wherein R¹, R², R³, R⁴ is individually selected from H and C1-C8 linear or branched alkyl.

3. The thermoplastic composition according to any one of the preceding claims, wherein the polar comonomer in C1) is selected from the group consisting of methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylic acid, methacrylic acid and vinyl acetate.

4. The thermoplastic composition according to any one of the preceding claims, wherein the polar comonomer in C1) is selected from the group consisting of acrylic acid, methacrylic acid and vinyl acetate.

5. The thermoplastic composition according to any one of the preceding claims, wherein the olefin in C1) is ethylene or propylene. The thermoplastic composition according to any one of the preceding claims, wherein the olefin in C1) is ethylene or propylene.

6. The thermoplastic composition according to any one of the preceding claims, wherein the content of polytetrafluoroethylene encapsulated styrene-acrylonitrile copolymer is less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt% or less than 0.005 wt% with respect to the thermoplastic composition, preferably the thermoplastic composition does not comprise polytetrafluoroethylene encapsulated styrene-acrylonitrile copolymer.

7. The thermoplastic composition according to any one of the preceding claims, wherein the composition has or is selected to have a LIL94 rating of at least V2 at a sample thickness of 1.5 mm and/or a LIL94 rating of at least V2 at a sample thickness of 0.8 mm.

8. The thermoplastic composition according to any one of the preceding claims, wherein the polycarbonate is a bisphenol A polycarbonate or a bisphenol A polycarbonate homopolymer.

9. The thermoplastic composition according to any one of the preceding claims, wherein the polycarbonate comprises a first polycarbonate having a melt flow rate according to ISO1133-1:2011 at 300 °C and 1.2 kg of 3.0 to 15 g/10min and a second polycarbonate having a melt flow rate according to ISO1133-1:2011 at 300 °C and 1.2 kg of 20 to 35 g/1 Omin.

10. The thermoplastic composition according to any one of the preceding claims, wherein the thermoplastic composition has a melt flow rate according to ISO1133- 1:2011 at 300 °C and 1.2 kg of from 3.0 to 35 g/1 Omin, preferably from 6.0 to 25 g/1 Omin, more preferably from 8.0 to 15 g/1 Omin.

11. The thermoplastic composition according to any one of the preceding claims, wherein the polycarbonate comprises post-consumer recycled (PCR) polycarbonate or post-industrial recycled (PIR) polycarbonate.

12. The thermoplastic composition according to any one of the preceding claims, wherein the flame retardant additive comprises or is potassium perfluorobutane sulfonate.

13. The thermoplastic composition according to any one of the preceding claims, wherein the thermoplastic composition does not comprise or substantially does not comprise acrylonitrile-butadiene-styrene, wherein the content of acrylonitrile- butadiene-styrene in the thermoplastic composition is less than 1.0 wt% or less than 0.1 wt% with respect to the thermoplastic composition.

14. The thermoplastic composition according to any one of the preceding claims, wherein the thermoplastic composition does not comprise or substantially does not comprise an impact modifier selected from the group consisting of styrene- butadiene-styrene (SBS), styrene-butadiene (SBR), styrene-ethylene-butadiene- styrene (SEBS), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-ethylene- propylene-diene-styrene (AES), styrene-isoprene-styrene (SIS), methyl methacrylate-butadiene (MB) and methyl methacrylate-butadiene-styrene (MBS), wherein the content of the impact modifier in the thermoplastic composition may e.g. be less than 1.0 wt% or less than 0.1 wt% with respect to the thermoplastic composition.

15. The thermoplastic composition according to any one of the preceding claims, wherein the further components comprise a mold release agent, preferably wherein the amount of the mold release agent is 0.1 to 1.0 wt% with respect to the thermoplastic composition.

16. The thermoplastic composition according to any one of the preceding claims, wherein the thermoplastic composition does not comprise or substantially does not comprise an anti-drip agent, wherein the content of anti-drip agent in the thermoplastic composition is less than 0.3 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt%, less than 0.005 wt%, with respect to the thermoplastic composition.

17. The thermoplastic composition according to any one of the preceding claims, wherein the amount of the polycarbonate is 90.0 to 97.5 wt%, the amount of the flame retardant additive is 0.01 to 1.0 wt%, the amount of the masterbatch is 2.0 to 5.0 wt%, with respect to the total composition.

18. An article comprising or consisting of the thermoplastic composition according to any one of the preceding claims.

19. The article according to claim 18, wherein the article is an automotive interior or exterior article.

20. The article according to claim 18 or 19, wherein the article is a screen bezel, a screen frame or a frame for electronic components, for example an infotainment panel or electronics screen framework.