GB1586910A

GB1586910A - Thermoplastic moulding compositions of polycarbonates and abs-polymers

Info

Publication number: GB1586910A
Application number: GB15424/78A
Authority: GB
Original assignee: Bayer AG
Current assignee: Bayer AG
Priority date: 1977-04-19
Filing date: 1978-04-19
Publication date: 1981-03-25
Also published as: DE2717165A1; NL7804125A; JPS53130749A; FR2388011A1; IT7848917A0

Description

(54) THERMOPLASTIC MOULDING COMPOSITIONS OF POLYCARBONATES AND ABS-POLYMERS (71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised under the Laws of Germany of 509 Leverkusen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to thermoplastic moulding compositions of polycarbonates and ABS - polymers.

More particularly, this invention relates to a process for the production of moulding compositions based on polycarbonates of aromatic hydroxy compounds and ABS polymers, in which polycarbonate and ABS are mixed in solution or in suspension and, after pre-concentration by evaporation, are extruded from an evaporation extruder.

Mixture of aromatic polycarbonates and ABS-polymers are already known (cf: German Auslegeschrift No. 1,170,141 and German Auslegeschrift No. 1,810,993).

For their production, polycarbonate and ABS are mixed with one another in the melt in conventional mixing machines, such as kneaders, mixing rolls or screw extruders and subsequently extruded.

As a result of extrusion (for example from screw extruders or kneaders), the polymer "alloy" is obtained in a particular form which primarily determines its physical properties. Thus, a composition containing an aromatic polycarbonate, in which the polycarbonate forms the continuous phase (matrix), mainly has the mechanical properties of the aromatic polycarbonate. If a styrene-acrylonitrile copolymer is the continuous phase, it is this phase which mainly determines the mechanical properties.

When mixtures of aromatic polycarbonates and ABS-polymers are made in screw extruders or kneaders, a continuous polycarbonate matrix is obtained only at polycarbonate contents of more than 700/ by weight. At lower polycarbonate contents almost complete mixing and, hence, a lower heat distortion temperature (determined according to Vicat B) are observed.

The present invention provides a process for the production of a thermoplastic moulding composition comprising: 1. 40 to 70 parts by weight of a polycarbonate based on at least one aromatic hydroxy compound; 2. 60 to 30 parts by weight of an ABS-polymer comprising a graft polymer of 15 to 60 parts by weight of a monomer mixture of 95 to 50% by weight of styrene, methyl methacrylate or a mixture thereof and 50 to 5 /n by weight of acrylonitrile, methacrylonitrile or mixtures thereof, graft polymerised onto 85 to 40 parts by weight of a rubber, wherein components 1 and 2 are dissolved or suspended in at least one organic solvent, wherein a major portion of the at least one solvent is removed in a first stage and the solid obtained is post-treated in an evaporation screw.

According to a particular embodiment of the invention, the ABS-polymer consists of 25 to 100/n by weight of the graft polymer and 3. 0 to 75/n by weight of a copolymer comprising 95 to 50% by weight of styrene, methyl styrene, methyl methacrylate or mixtures thereof, 50 to 5% by weight of acrylonitrile, methacrylonitrile, methyl methacrylate or mixtures thereof.

The moulding compositions show improved heat distortion and elongation at break compared with moulding compositions produced by melt-mixing in screw extruders or kneaders. The Vicat temperature is around 10"C higher and elongation at break increase from around 50/ to around 100/ by comparison with a comparable moulding composition produced by melt-mixing in a twin-screw extruder.

The moulding compositions produced in accordance with the present invention have a continuous polycarbonate matrix, even with polycarbonate contents of less than 70/, although a more homogeneous mixture (and hence no distinct phase formation) is to be expected.

In the context of the invention, aromatic polycarbonates (1) are homopolycarbonates and conolycarbonates based, for example, on one or more of the following bisphenols: hydroquinone, resorcinol, dihydroxy diphenyls, bis (hydroxy - phenyl) - alkanes, bis - (hydroxyphenyl) - cycloalkanes, bis - (hydroxyphenyl) - sulphides, bis - (hydroxyphenyl) - ethers, bis (hydroxyphenyl) - ketones, bis - (hydroxyphenyl) - sulphoxides, bis (hydroxyphenyl)- sulphones, and a,a - bis - (hydroxyphenyl) - diisopropyl benzenes and their nucleus-alkylated and nucleus-halogenated compounds. These and other suitable aromatic dihydroxy compounds are described, for example, in U.S.Patent Nos. 3,028,365; 2,999,835; 3,148,172; 3,271,368; 2,991,273; 3,271,367; 3,280,078; 3,014,891 and 2,999,846, in German Offenlegungsschrifts Nos. 1,570,703; 2,063,050; 2,063,052; 2,211,956; 2,211,957, in French Patent No. 1,561,518 and in H.

Schnell, "Chemistry and Physics of Polycarbonates", Interscience Publishers, New York, 1964.

Preferred bisphenols correspond to formula I

in which the R's may be the same or different and represents H, C -C4- alkyl, Cl or Br and in which X represents a direct bond, C1-C8-alkylene, C2Ca-alkylidene, CsC,5-cycloalkylene, C,-C,,-cycloalicyiidene, --SO,- or

Specific Examples are: 4,4'-dihydroxyphenyl; 2,2-bis-(4-hydroxyphenyl)-propane; 2,4-bis-(4-hydroxyphenyl)-2-methyl butane; 1,1 -bis-(4-hydroxyphenyl)-cyclohexane; a,-bis-(4-hydroxyphenyl)-p-diisopropyl benzene; 2,3,-bis-(3-methyl-4-hydroxyphenyl)-propane; 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane; bis-(3,4-dimethyl-4-hydroxyphenyl)-methane; 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane; bis-(3,5-dimethyl-4-hydroxyphenyl)-sulphone; 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane; bis-(3 ,5-dimethyl-4-hydroxyphenyl)-sulphone; 2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methyl butane; 1, -bis-(3 ,5-dimethyl-4-hydroxyphenyl)-cyclohexane; a,a-bis-(3,5-dimethyl-4-hydroxyphenyl)-pdiisopropyl benzene; 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane; and 2,2-bls-(3 ,5-dibromo-4-hydroxyphenyl)-propane.

Particularly preferred bisphenols are: 2,2-bis-(4-hydroxyphenyl)-propane; 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane; 2,2-bis-(3,5-dichloro-4-hydroxyphenyl)-propane; 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane; and 1,1 -bis-(4-hydroxyphenyl)-cyclohexane.

Preferred aromatic polycarbonates are those based on one or more of the preferred bisphenols mentioned above. It is particularly preferred to use copolycarbonates based on 2,2 - bis - (4 - hydroxyphenyl) - propane and one of the other particularly preferred bisphenols mentioned above. It is also particularly preferred to use monopolycarbonates based on 2,2 - bis - (4 - hydroxyphenyl) propane or 2,2 - bis - (3,5 - dimethyl - 4 - hydroxyphenyl) - propane.

The aromatic polycarbonates can be produced by known methods, for example by the melt transesterification process from bisphenols and diphenyl carbonate and by the two-phase interfacial process from bisphenols and phosgene, as described in the above-mentioned literature.

The aromatic high molecular weight polycarbonates can be branched by the incorporation of small quantities, preferably between 0.05 and 2 mol / (based on the diphenols used), of trifunctional or more than trifunctional compounds, particularly those having three or more phenolic hydroxy groups.

Polycarbonates of this type are described, for example, in German Offenlegungsschriften Nos. 1,570,533; 1,595,762; 2,116,974; 2,113,347 in British Patent Specification No. 1,079,821, in U.S. Patent Specification No. 3,544,514 and in German Offenlegungsschrift No. 25 00 092.

Some of the compounds containing three or more than three phenolic hydroxy groups which may be used are, for example, phloroglucinol, 4,6 - dimethyl 2,4,6 - tri - (4 - hydroxyphenyl) -2 - heptane, 4,6 - dimethyl - 2,4,6 - tri - (4 hydroxyphenyl) - heptane, 1,4,5 - tri - (4 - hydroxyphenyl) - benzene, 1,1,1 - tri (4 - hydroxyphenyl) - ethane, tri - (4 - hydroxyphenyl) - phenyl methane, 2,2 bis - [4,4 - bis - (4 - hydroxyphenyl) - cyclohexyl] - propane, 2,4 - bis - (4 hydroxyphenylisopropyl) - phenol, 2,6 - bis - (2 - hydroxy - 5' - methylbenzyl) 4 - methyl phenol, 2 - (4 - hydroxyphenyl) - 2 - (2,4 - dihydroxyphenyl)propane, hexa - [4 - (4 - hydroxyphenylisopropyl) - phenyl] - orthoterephthalic acid ester, tetra - (4 - hydroxyphenyl)- methane, tetra - [4 - (4 hydroxyphenylisopropyl) - phenoxy] - methane and 1,4 - bis - [4',4"dihydroxytriphenyl) - methyl] - benzene. Some of the other trifunctional compounds are 2,4 - dihydroxy benzoic acid, trimesic acid, cyanuric chloride and 3,3 - bis - (4 - hydroxyphenyl) - 2 - oxo - 2,3 - dihydroindole.

The aromatic high molecular weight polycarbonates generally have average (numerical average) molecular weights mW of at least 10,000, more especially from 10,000 to 200,000 and preferably from 20,000 to 80,000, as determined by measuring the relative viscosity in CH2Cl2 at 250C for a concentration of 0.5/ by weight.

The graft polymers (2) are produced by polymerising the monomers, preferably styrene and acrylonitrile, in the presence of a diene rubber. In these products, a monomer mixture of from 95 to 50/ by weight of styrene, methyl methacrylate or mixtures thereof and 5 to 50/ by weight of acrylonitrile, methacrylonitrile or mixtures thereof are polymerised in the presence of a rubber.

The graft copolymer can consist of 80 to 10 parts by weight of rubber and 20 to 90 parts by weight of a copolymer, preferably a styrene-acrylonitrile copolymer which is at least partly chemically attached to the rubber ("grafted on"). In general, only part of the styrene and acrylonitrile is in fact grafted on, since, non-grafted styreneacrylonitrile copolymer is generally present as well.In the context of the present invention, diene rubbers are, in particular, polybutadiene, butadiene/styrene copolymers containing up to 30% by weight of copolymerised styrene, copolymers of butadiene and acrylonitrile containing up to 20/ by weight of acrylonitrile, and copolymers of butadiene with up to 20 /n by weight of a lower alkyl ester of acrylic or methacrylic acid (for example methylacrylate, ethylacrylate, methyl methacrylate and ethyl methacrylate).

Ethylenëpropylene/diene polymers, so-called EPDM rubbers, are also suitable. Basically, all elasticising components can be used, provided, they show rubber-elastic behaviour.

The graft copolymers can be obtained in known manner by the radical polymerisation of styrene and acrylonitrile in the presence of the rubber in bulk, emulsion, suspension and by combined processes such as bulk/suspension polymerisation or solution/precipitation polymerisation. For example graft polymers based on polybutadiene are often made by polymerising the monomers, such as styrene and acrylonitrile, in the presence of a latex of the butadiene polymer, i.e. by emulsion polymerisation. The polymer particles in the latex of the butadiene polymer, generally, have a size in the range from 0.2 to 5 flw.

The thermoplastic moulding compositions of the present invention are obtained by initially dissolving or suspending the constituents polycarbonate and ABS-polymer in a solvent. Suitable solvents are, for example, methylene chloride, chloroform, chlorobenzene, tetrahydrofuran, dioxane, dimethyl formamide and dimethyl sulphoxide. The polycarbonate mostly dissolves completely, the ABSpolymer, generally, forms a suspension, the styrene-acrylonitrile copolymer dissolving whilst the rubber is insoluble.

The two solutions or suspensions are then mixed together in the required ratio and concentrated by evaporation in suitable evaporators to form an approximately 45 to 98% by weight melt. Any known apparatus can be used which is suitable for the concentration of polymer solutions by evaporation (ef R. Erdmenger in "Maschinenmarkt", Wiirzburg, 80 (1974) 1,).

The residual solvents are then removed in intensive kneading machines, for example self-cleaning twin-screw extruders rotating in the same direction, and the solvent-free polymer melt is extruded and granulated by known methods.

Even after further extrusion, the continuous polycarbonate matrix remains intact. Thus, fillers, glassfibres, pigments or other additives, such as stabilisers, flameproofing agents, flow aids, lubricants, mould release agents, antistatic agents, can, be added to the moulding compositions.

The moulding compositions according to the invention can be used for the production of any type of mouldings. In particular, by injection moulding shaped articles can be obtained which are, in particular, useful for applications requiring high dimensional stability under heat, good ball identation-hardness according to VDE 0470 and high elongation at break.

I. Aromatic polycarbonates.

General procedure for producing polycarbonates Approximately 454 parts of 4,4' - dihydroxydiphenyl - 2,2 - propane and 9.5 parts of p-tert. - butyl phenol were suspended in 1.5 litres of water. In a threenecked flask equipped with a stirrer and gas inlet pipe, the oxygen was removed from the reaction mixture by passing nitrogen through with stirring for 15 minutes.

355 parts of a 45/ sodium hydroxide solution and 1000 parts of methylene chloride were then added. The mixture was cooled to 250C. 237 parts of phosgene were then added over a period of 120 minutes during which the above-mentioned temperature was maintained by cooling. An additional quantity of 75 parts of a 45/ sodium hydroxide solution was added after 15 to 30 minutes when the phosgene had begun to be taken up. 1.6 parts of triethylamine were added to the solution formed and the mixture was stirred for another 15 minutes. A highly viscous solution was obtained, its viscosity being adjusted by the addition of methylene chloride. The aqueous phase was separated off and the organic phase was washed with water until free from salt and alkali. The polycarbonate was isolated from the washed solution and dried.The polycarbonate had a relative viscosity of from 1.29 to 1.30, as measured on a 0.5% solution of methylene chloride at 200C. This corresponds approximately to a molecular weight of 32,000. The polycarbonate thus obtained was extruded and granulated.

A.) Polycarbonate based on 4,4' - dihydroxy diphenyl propane - 2,2 (bisphenol A) having a relative viscosity 71rel of 1.30, M,s=28,000.

B.) Polycarbonate based on 90 mole / bisphenol A and 10 mole / of 4,4' dihydroxy - 3,3',5,5' - tetrabromodiphenyl propane - 2,2 (tetrabromobisphenol A) having a relative viscosity 17rel of 1.33s MLs=37L000 II. ABS-polymers C.) ABS-polymer of: 30 parts by weight of a graft polymer produced by grafting 35 parts by weight of styrene and 15 parts by weight of acrylonitrile onto 50 parts by weight of a coarsely divided polybutadiene (according to German Auslegeschrift Nos.

1,247,665 and 1,269,360 by emulsion polymerisation), the polybutadiene graft base present in latex form having an average particle diameter of from 0.3 to 0.42 and 70 parts by weight of a styrene-acrylonitrile copolymer with a styreneacrylonitrile ratio of 70:30 and a relative viscosity of 1.45 (as measured in CH2Cl2 at 25"C with a concentration of 5 g/l).

D.) ABS-polymer of: 30 parts of weight of a graft polymer produced by grafting 25 parts by weight of a styrene and 5 parts by weight of acrylonitrile onto 70 parts by weight of a coarsely divided polybutadiene (according to German Auslegeschrift Nos. 1,247,665 and 1,269,360), the polybutadiene graft base present in latex form having an average particle diameter of from 0.3 to 0.4 ,u, and 70 parts by weight of a copolymer of styrene and acrylonitrile in a ratio of 70:30 having a relative viscosity of 1.65.

EXAMPLE 1 (Comparison Example) 50 parts by weight of polycarbonate A were mixed with 50 parts by weight of ABS-polymer C in a twin screw extruder at 2600C and subsequently granulated.

EXAMPLE 2 18 kg of ABS-polymer C were dissolved or suspended in a solvent mixture of 265 kg of methylene chloride and 175 kg of chlorobenzene. 42 kg of polycarbonate A were then added in portions, followed by stirring until the polycarbonate had completely dissolved.

The polymer solution was then introduced with thorough stirring into a suitable evaporator and concentrated by evaporation at around 150 C to form a 40/ solid-containing rational which was then fully evaporated in a unidirectionally rotating self-cleading twin screw extruder (ZSK 53). The maximum screw temperature was adjusted to 2700 C, the melt temperature was 2600C.

EXAMPLES 3 TO 6 The moulding compositions of Examples 3 to 6 were produced in the required compositions by the process described in principle in Example 2.

The corapositions and some characteristics mechanical data are shown in the following Table: TABLE 2 3 4 5 6 Examples I (Comparison) (Comparison) Polycarbonate A) / by weight 50 50 65 - 45 60 Polycarbonate B) / by weight - - 60 55 - ABS-polymer C) / by weight 50 50 - 40 - 40 ABS-polymer D) / -by weight - ~ 35 i - - Vicat B-temperature "C 113 125 133 136 120 131 Ball identation hardness VDE 0470 OC 111 123 130 135 116 128 Elongation at break / 40 100 125 130 90 125 Vicat B temperature, measured in accordance with DIN 53 460 Ball identation Hardness, measured in accordance with VDE 0470 Elongation at break, measured in accordance with DIN 53 455.

WHAT WE CLAIM IS: 1. A process for the production of a thermoplastic moulding composition comprising: 1.) 40 to 70 parts by weight of a polycarbonate based on at least one aromatic hydroxy compound; and 2.) 60 to 30 parts by weight of an ABS-polymer comprising a graft polymer of 15 to 60 parts by weight of a monomer mixture of 95 to 50% by weight of styrene, methyl methacrylate or a mixture thereof, and 50 to 5 /n by weight of acrylonitrile, methacrylonitrile or a mixture thereof, graft polymerised onto 85 to 40 parts by weight of a rubber, wherein the components 1 and 2 are dissolved or suspended in at least one organic

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

D.) ABS-polymer of:

30 parts of weight of a graft polymer produced by grafting 25 parts by weight of a styrene and 5 parts by weight of acrylonitrile onto 70 parts by weight of a coarsely divided polybutadiene (according to German Auslegeschrift Nos. 1,247,665 and 1,269,360), the polybutadiene graft base present in latex form having an average particle diameter of from 0.3 to 0.4 ,u, and

70 parts by weight of a copolymer of styrene and acrylonitrile in a ratio of 70:30 having a relative viscosity of 1.65.

EXAMPLE 1 (Comparison Example)

50 parts by weight of polycarbonate A were mixed with 50 parts by weight of ABS-polymer C in a twin screw extruder at 2600C and subsequently granulated.

EXAMPLE 2

18 kg of ABS-polymer C were dissolved or suspended in a solvent mixture of

265 kg of methylene chloride and 175 kg of chlorobenzene. 42 kg of polycarbonate A were then added in portions, followed by stirring until the polycarbonate had completely dissolved.

The polymer solution was then introduced with thorough stirring into a suitable evaporator and concentrated by evaporation at around 150 C to form a 40/ solid-containing rational which was then fully evaporated in a unidirectionally rotating self-cleading twin screw extruder (ZSK 53). The maximum screw temperature was adjusted to 2700 C, the melt temperature was 2600C.

EXAMPLES 3 TO 6 The moulding compositions of Examples 3 to 6 were produced in the required compositions by the process described in principle in Example 2.

The corapositions and some characteristics mechanical data are shown in the following Table: TABLE

2 3 4 5 6 Examples I (Comparison) (Comparison) Polycarbonate A) / by weight 50 50 65 - 45 60 Polycarbonate B) / by weight - - 60 55 - ABS-polymer C) / by weight 50 50 - 40 - 40 ABS-polymer D) / -by weight - ~ 35 i - - Vicat B-temperature "C 113 125 133 136 120 131 Ball identation hardness VDE 0470 OC 111 123 130 135 116 128 Elongation at break / 40 100 125 130 90 125 Vicat B temperature, measured in accordance with DIN 53 460 Ball identation Hardness, measured in accordance with VDE 0470 Elongation at break, measured in accordance with DIN 53 455.

WHAT WE CLAIM IS: 1. A process for the production of a thermoplastic moulding composition comprising: 1.) 40 to 70 parts by weight of a polycarbonate based on at least one aromatic hydroxy compound; and 2.) 60 to 30 parts by weight of an ABS-polymer comprising a graft polymer of

15 to 60 parts by weight of a monomer mixture of 95 to 50% by weight of styrene, methyl methacrylate or a mixture thereof, and 50 to 5 /n by weight of acrylonitrile, methacrylonitrile or a mixture thereof, graft polymerised onto 85 to 40 parts by weight of a rubber, wherein the components 1 and 2 are dissolved or suspended in at least one organic

solvent, wherein a major portion of the at least one solvent is removed in a first stage and the solid obtained is post-treated in an evaporation screw.
2. A process, as claimed in claim 1, wherein the ABS-polymer consists of 25 to 100/ by weight of the graft polymer and 3.) 0 to 75% by weight of a copolymer comprising: 95 to 50/ by weight of styrene, methyl styrene methyl methacrylate or a mixture thereof and 50 to 5% by weight of acrylonitrile, methacrylonitrile, methyl methacrylate or a mixture thereof and wherein the component 3 is also dissolved or suspended in at least one organic solvent with components 1 and 2.
3. A process as claimed in claim 1 or 2, wherein the organic solvent is methylene chloride, chlorobenzene or a mixture thereof.
4. A process as claimed in any of claims 1 to 3, wherein the polycarbonate is a copolycarbonate based on 2,2 - bis - (4 - hydroxyphenyl) - propane and 2,2 - bis (3,5 - dimethyl - 4 - hydroxyphenyl) - propane, 2,2 - bis - (3,5 - dichloro - 4 hydroxyphenyl)- propane, 2,2 - bis - (3,5 - dibromo - 4 - hydroxyphenyl) - propane or 1,1 - bis - (4 - hydroxyphenyl) - cyclohexane.
5. A process as claimed in any of claims 1 to 3, wherein the polycarbonate is a monopolycarbonate based on 2,2 - bis - (4 - hydroxyphenyl) - propane or 2,2 bis - (3,5 - dimethyl - 4 - hydroxyphenyl) - propane.
6. A process as claimed in any of claims 1 to 5, wherein the polycarbonate has a molecular weight (numerical average) of from 20,000 to 80,000 as determined by the relative viscosity in CH2Cl2 at 250C for a concentration of 0.5% by weight.
7. A process as claimed in any of claims 1 to 6, wherein the graft copolymer 2 comprises styrene and acrylonitrile.
8. A process as claimed in claim I for the production of a thermoplastic moulding composition substantially as herein described with reference to any of the specific Examples 2 to 4 and 6.
9. A thermoplastic moulding composition when prepared by a process as claimed in any of claims 1 to 8.
10. A moulded article produced from a thermoplastic moulding composition as claimed in claim 9.