Thermoplastic ABS composition reinforced with natural fibres

Abstract

The present invention relates to a thermoplastic ABS composition reinforced with natural fibres, which comprises an ABS polymer, natural fibres, a compatibilizing polymer, and processing aids comprising a lubricant and titanium dioxide. It relates also to a moulded article prepared from the thermoplastic composition and to its use in extrusion, injection, compression moulding and 3D printing.

Claims

1. Thermoplastic composition comprising: 1) an acrylonitrile-butadiene-styrene (ABS) polymer, 2) natural fibres, 3) a compatibilizing polymer, and 4) processing aids comprising a lubricant and titanium dioxide, wherein the amount of titanium dioxide is comprised from 1 to 10 wt. % wherein the compatibilizing polymer is a copolymer of styrene and maleic anhydride or a copolymer of styrene maleic anhydride and N-phenylmaleimide.

2. Thermoplastic composition according to claim 1, wherein the amount of ABS polymer is comprised from 40 to 90 wt. %.

3. Thermoplastic composition according to claim 1, wherein the ABS polymer comprises at least one grafted ABS polymer, with a glass transition temperature Tg<0 C.

4. Thermoplastic composition according to claim 3, additionally comprising at least one rubber-free copolymer.

5. Thermoplastic composition according to claim 3, wherein the grafted ABS is obtainable by bulk polymerization process containing at least 50 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, in the presence of from 3 to 50 parts of a butadiene polymer.

6. Thermoplastic composition according to claim 3, wherein the grafted ABS is obtainable by emulsion polymerization process containing at least 25 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, in the presence of not more than 75 parts a butadiene polymer.

7. Thermoplastic composition according to claim 6, wherein the grafted ABS is obtainable by emulsion polymerization process containing at least 40 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, in the presence of at least 50 parts of a butadiene polymer.

8. Thermoplastic composition according to claim 4, wherein the rubber-free copolymer is comprised of styrene and acrylonitrile in a weight ratio of from 90:10 to 50:50.

9. Thermoplastic composition according to claim 1, wherein the natural fibres are cellulose based natural fibres or wood fibres.

10. Thermoplastic composition according to claim 1, wherein the lubricant is selected from the group consisting of stearates, paraffin oils, polyethylene waxes, lauric acid, palmitic acid, stearic acid, stearic acid amides, ethylenediamine, glycerol, and mixtures thereof.

11. Thermoplastic composition according to claim 1, further comprising antioxidants, antistatic agents, mould releasing agents, colorants, pigments, mineral fillers, visible light and UV stabilizers, and mixtures thereof.

12. A moulded article prepared from the thermoplastic composition of claim 1.

13. A method of manufacturing an article comprising using the thermoplastic composition of claim 1 in extrusion, injection, compression moulding or 3D printing.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIGURE

(2) The FIGURE illustrates the surface appearance of the thermoplastic composition of the invention prepared according to Example 2 in comparison to the surface appearance of the thermoplastic composition prepared according to Comparative example, which does not contain titanium dioxide.

DETAILED DESCRIPTION OF THE INVENTION

(3) The object of the present invention is a thermoplastic composition comprising: 1) an acrylonitrile-butadiene-styrene (ABS) polymer, 2) natural fibres, 3) a compatibilizing polymer, and 4) processing aids comprising a lubricant and titanium dioxide, wherein the amount of titanium dioxide is comprised from 1 to 10 wt. %.

(4) In the description, the components of the thermoplastic composition are referred as shown in Table I:

(5) TABLE-US-00001 TABLE I Component Definition A Acrylonitrile-butadiene-styrene (ABS) polymer B Natural fibres C Compatibilizing polymer D Lubricant E Titanium dioxide

(6) The authors of the present invention have developed a thermoplastic composition showing an optimized impact resistance/flow ability ratio, which is obtained by a simple process, easy to implement industrially. The composition shows well-balanced mechanical and thermal properties, it is environmentally friendly and can be used in a wide range of applications, such as extrusion, injection, compression moulding and 3D printing. Surprisingly, the moulded articles obtained from the thermoplastic composition show a uniform distribution of the natural fibre and an elegant surface appearance.

(7) In the present description as well as in the claims, the singular forms a and an include also the plural reference unless the context clearly indicates otherwise.

(8) In the present description the specified parts are always parts by weight and the specified % values are always wt. % unless otherwise stated. The sum of the percentages of the components in the thermoplastic composition of the invention are 100 wt. %. In the context of the present invention percentages have 10% of margin. In the context of the present invention the term about means 10%.

(9) The glass transition temperature (Tg) of compounds disclosed in this description is determined using standard methods and devices, such as the differential scanning calorimeter (DSC) performed on a DSC/TGA STARe (mettler-toledo). Standard parameters are applied on a sample mass of for example about 60 mg. Standard conditions are for example the temperature program between 35 C. and 220 C., two times heating and one cooling, both at a rate of 10 C./min and an air flow of 20 ml/min; or the temperature program between 130 C. and 200 C., two times heating and one cooling, both at a rate of 20 C./min and an nitrogen flow of 50 ml/min.

(10) ABS Polymer

(11) The thermoplastic composition of the invention comprises an acrylonitrile-butadiene-styrene (ABS) polymer (Component A).

(12) The ABS polymer is a well-known polymer comprising acrylonitrile, butadiene and styrene as monomers. In the present invention, the expression ABS is used in the generic sense and includes known equivalents for acrylonitrile, such as methacrylonitrile and propacrylonitrile, among others; for butadiene, such as isoprene, and chloroprene, among others, and for styrene such as -methyl styrene and halostyrene, among others.

(13) Usually component A comprises at least one grafted ABS polymer, with a glass transition temperature Tg<0 C., (Component A1). In a preferred embodiment it comprises additionally at least one rubber-free copolymer (Component A2).

(14) The amounts of components A1 and optionally A2 are given in wt. %. Generally in the thermoplastic composition of the invention the amount of ABS polymer is comprised from 40 to 90 wt. %, preferably from 50 to 80 wt. %, and more preferably from 60 to 75 wt. %.

(15) In the thermoplastic composition of the invention the content of grafted ABS polymer is generally comprised from 15 to 70 wt. %, preferably from 18 to 50 wt. %, and more preferably from 20 to 35 wt. %; and the content of rubber-free polymer, if present, is comprised from 25 to 65 wt. %, preferably from 30 to 60 wt. %, and more preferably from 35 to 50 wt. %.

(16) The determination of the average molecular weight Mw of component A2 is carried out by using standard methods well known by the skilled person, for example, using Gel Permeation Chromatography (GPC), with tetrahydrofuran as solvent, polystyrene as standard polymer, and detection by refractive index.

(17) Grafted ABS polymer

(18) The grafted ABS polymer can be obtained by either by bulk polymerization or by emulsion polymerization. Preferably it is obtained by emulsion polymerization. Methods for preparing grafted ABS polymer by emulsion polymerization are disclosed, for example, in EP-A-0436381 and EP-A-0522710. Methods for preparing grafted ABS polymer by bulk polymerization are disclosed, for example, in EP-A-0810242.

(19) In a preferred embodiment the grafted ABS is obtainable by bulk polymerization process containing at least 50 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of from 3 to 50 parts of a butadiene polymer. Preferably a butadiene polymer containing an average particle diameter d.sub.50 from 100 to 10000 nm, preferably 200 to 5000 nm, more preferably 400 to 2000 nm. In a preferred embodiment, the butadiene rubber content is comprised from 3 to 50 wt. %, more preferably from 5 to 30 wt. %, and yet more preferably from 6 to 25 wt. %.

(20) In a preferred embodiment the grafted ABS is obtainable by emulsion polymerization process containing at least 25 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of not more than 75 parts a butadiene polymer. Preferably a mono, bi-, tri- or multimodal butadiene polymer containing particle populations showing an average particle diameter d.sub.50 from 50 to 600 nm with a butadiene rubber containing from 35 to 97 (wt. %).sup.1 of gel content determined using, for example, Time-Domain NMR devices, such as Minispec mq20 NMRPolymer Research System (Bruker).

(21) In a preferred embodiment the grafted ABS is obtainable by emulsion polymerization process containing at least 40 parts, preferably from 40 to 48, more preferably from 42 to 48, of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of at least 50 parts, preferably from 52 to 60, more preferably 52 to 58, of a butadiene polymer. Preferably a mono-, bi-, tri- or multimodal butadiene polymer containing particle populations showing an average particle diameter d.sub.50 selected from 50 to 200 nm, preferably from 65 to 150 nm, more preferably from 120 to 130 nm; from 220 to 340 nm, preferably from 240 to 320 nm, more preferably from 260 to 300; and from 340 nm to 480 nm, preferably from 350 to 450 nm, more preferably from 360 to 420. In a preferred embodiment, the butadiene rubber contains 35 to 97 (wt. %).sup.1 of gel content.

(22) In another embodiment, the grafted ABS is a polymer wherein styrene is replaced wholly or partially by -methyl styrene, maleic anhydride, methyl methacrylate or N-phenyl maleimide.

(23) In another embodiment, the grafted ABS is a polymer, which further comprises small amounts, 1 wt. % to 10 wt. %, of (meth)acrylate linear or branched C.sub.2-C.sub.8 alkyl esters, such as ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate.

(24) Grafted ABS are available commercially, for example, through the companies ELIX polymers and Korea Kumho Petrochemical: Grafted ABS polymer produced by emulsion polymerization with a butadiene content comprised between 51 and 54 wt. % commercially available under the trade name ELIX 152I (ELIX Polymers); Grafted ABS polymer produced by emulsion polymerization with a butadiene content comprised between 54 and 58 wt. % commercially available under the trade name ELIX 158I (ELIX Polymers); Mono-modal grafted ABS polymer produced by emulsion polymerization with a butadiene content comprised between 50 and 60 wt. % commercially available under the trade name KUMHO HR181 (Korea Kumho Petrochemical); grafted ABS produced by bulk polymerization is commercially available under the trade name MAGNUM 3504 (Trinseo).

(25) Rubber-Free Copolymer

(26) The optional rubber-free copolymer is generally comprised of styrene and acrylonitrile in a weight ratio of from 90:10 to 50:50, preferably from 90:10 to 60:40, and more preferably from 90:10 to 70:30, the styrene being able to be replaced wholly or partially by -methyl styrene, maleic anhydride or N-phenylmaleimide. Preferably the rubber-free copolymer comprises styrene and acrylonitrile as monomers, more preferably in a ratio of 70:30 to 80:20, and yet more preferably 73:27.

(27) In a preferred embodiment the rubber-free component forms a hard phase with a glass transition temperature Tg of at least 20 C.

(28) In a preferred embodiment the rubber-free copolymer has a molecular weight comprised from 20,000 to 300,000 Da; preferably from 100,000 to 200,000 Da; and more preferably from 100,000 to 145,000 Da.

(29) Rubber-free polymers are available commercially, for example, through the company ELIX polymers: SAN polymer showing a molecular weight of about 105,000 Da, wherein the styrene:acrylonitrile ratio is 73:27, commercially available under the trade name ELIX 230G (ELIX Polymers); SAN molecular weight of about 140,000, wherein the styrene:acrylonitrile=73:27, commercially available under the trade name ELIX 260G (ELIX Polymers); SAN molecular weight of about 165,000, wherein the styrene:acrylonitrile=73:27, commercially available under the trade name ELIX 280G (ELIX Polymers).

(30) Natural Fibres

(31) The thermoplastic composition of the invention comprises natural fibres (Component B)

(32) Natural fibres are selected from flax, hemp, palm, cellulose, sisal, kenaf, bamboo, jute, sisal, wheat straw, wood fibres, and mixtures thereof.

(33) Preferably natural fibres are cellulose based natural fibres or wood fibres, more preferably wood fibres; yet more preferably refined wood fibres; even more preferably thermo-mechanically treated wood fibres.

(34) In a preferred embodiment a major fraction of the natural fibres have an aspect ratio of at least 10:1, more preferably at least 20:1, and yet more preferably at least 25:1.

(35) In a preferred embodiment a minimum of 98 wt. % of the natural fibres shows an average length of >200 m and a maximum of moisture content of 7%.

(36) Thermo-mechanically treated wood fibres can be obtained as disclosed in International patent applications WO-A-2006/001717 or WO-A-2011/002314. They can also be obtained commercially under the trade name Woodforce Natural FAST and Woodforce Natural Standard in natural colour, or in black colour as Woodforce Black FAST and Woodforce Black Standard (Sonae Industria).

(37) Generally the amount of natural fibres in the thermoplastic composition is below 40 wt. %, preferably it is comprised from 5 to 37 wt. %, more preferably from 10 to 35 wt. %, more preferably from 15 to 33 wt. %, and yet more preferably from 18 to 30 wt. %.

(38) Compatibilizing Polymer

(39) The thermoplastic composition of the invention includes a compatibilizing polymer (Component C), which is a polymer with a reactive group. The reactive group is preferably an epoxy group, N-phenylmaleimide(N-PMI) group and maleic anhydride (MAH) group. Any compatibilizer having these reactive groups may be used without limitation in the present invention. The compatibilizer is preferably a polymer, which includes any of the following monomers glycidyl methacrylate, maleic anhydride, N-phenylmaleimide, and mixtures thereof in combination with styrene or -methylstyrene. More preferably the compatibilizer is a copolymer of styrene and maleic anhydride (SMA) or a copolymer of styrene, maleic anhydride and N-phenylmaleimide (SMI); yet more preferably it is a copolymer of styrene and maleic anhydride (SMA).

(40) Generally the molecular weight of the styrene maleic anhydride copolymer (SMA) is 20,000-300,000 Da, wherein the content of MAH is below 50 wt. %; preferably it is 50,000-180,000 Da with MAH content preferably from 15 wt. % to 35 wt. %.

(41) Generally the molecular weight of the styrene, maleic anhydride and N-phenylmaleimide copolymer (SMI) is 20,000-300,000 Da, wherein the content of MAH is below 30 wt. % and the content of N-PMI is below 55 wt. %; preferably a molecular weight 90,000-200,000 Da with the content of MAH preferably from 1 wt. % to 25 wt. % and the N-PMI content preferably from 10 wt. % to 55 wt. %. and more preferably from 10 wt. % to 35 wt. %.

(42) The polymeric compatibilizers are commercially available. Suitable compatibilizers are, for example, SMA polymer showing a molecular weight of about 110,000, MAH content of 23 wt. %, commercially available under the trade name XIRAN SZ23110 (Polyscope Polymers), SMA polymer showing a molecular weight of about 120,000, MAH content of 26 wt. %, commercially available under the trade name XIRAN SZ26120 (Polyscope Polymers), SMI polymer showing a molecular weight of about 145,000, MAH content of 10 wt. %, N-PMI content of 18 wt. %, commercially available under the trade name XIRAN IZ1018M (Polyscope Polymers), SMI polymer showing a molecular weight of about 150,000, MAH content of 7 wt. %, N-PMI content of 21 wt. %, commercially available under the trade name XIRAN 0721M (Polyscope Polymers).

(43) Generally the amount of compatibilizing polymer in the thermoplastic composition is from 1 to 10 wt. %, preferably it is comprised from 2 to 8 wt. %, and more preferably from 2 to 5 wt %.

(44) Processing Aids

(45) The thermoplastic composition of the invention comprises a lubricant (Component D) and titanium dioxide (Component E) as processing aids.

(46) The lubricant includes stearates, paraffin oils, polyethylene waxes, lauric acid, palmitic acid, stearic acid, stearic acid amides, ethylenediamine, glycerol, and mixtures thereof; preferably it is ethylene bis stearamide (EBS), pentaerythritol tetrastearate (PETS), paraffin oils, stearic acid, glycerol monostearate, stearyl stearate, butyl strearate, polyethylene waxes, or mixtures thereof; more preferably it is ethylene bis stearamide (EBS).

(47) In a preferred embodiment, the processing aid consists of a lubricant and titanium dioxide. In a more preferred embodiment the processing aid consists of a combination of ethylene bis stearamide (EBS) and titanium dioxide.

(48) Generally the amount of lubricant in the thermoplastic composition is from 1 to 5 wt. %, preferably it is comprised from 1.5 to 3.5 wt. %, and more preferably from 1.8 to 2.5 wt.

(49) The amount of titanium dioxide in the thermoplastic composition of the invention is comprised from 1 to 10 wt. %, preferably from 1.5 to 7 wt. %, more preferably from 2 to 5 wt. %.

(50) As shown in Comparative example, the use of the moulding compositions of the prior art not including a specific amount of titanium dioxide produces moulded parts with bad surface finishes, in particular, flow lines described as visible marks on the moulded articles surfaces that indicate the direction of the flow of the melt into the mould and wavy surface appearances caused by improper flow of the melt into the mould due to unavoidable difference between melt flow of the composite. The use of a specific amount of titanium dioxide in the thermoplastic composition of the invention surprisingly accomplishes the uniform distribution of the natural fibres in the polymeric matrix and prevents the formation of flow marks improving the surface appearance of the articles, avoiding additional surface treatments of the object.

(51) The colouring of thermoplastic compositions is being used for article design since it is excellent in colour properties. In this context, the use of titanium dioxide pigment produced also an excellent pre-coloured matrix base natural fibre reinforced thermoplastic with high deep colour shade. This pre-coloured matrix base can be used with other pigments or dyes for new colour development, even not only for a single colour tone, to obtain good aesthetics surface finish moulded parts in natural-fibres reinforced ABS thermoplastics compositions, in a single stage.

(52) Additives

(53) The necessary or advantageous additives, for example, antioxidants, mould releasing agents, pigments, visible light stabilizers, UV stabilizers, blowing agents, foaming additives, antistatic agents, antiblocking agents, heat stabilizers, impact modifiers, plasticizers, biocides, flame retardants, tackifiers, colorants, pigments, mineral fillers, and mixtures thereof, can be added to the thermoplastic compositions during their preparation, further processing, working up and final forming.

(54) In a preferred embodiment, the thermoplastic composition comprises antioxidants, antistatic agents, mould releasing agents, colorants, pigments, mineral fillers, visible light and UV stabilizers, and mixtures thereof.

(55) Said antioxidants include, for example, phosphorus-based antioxidants (i.e. phosphites), phenol-based antioxidants, thioesters, and hindered phenolic anti-oxygen scavengers.

(56) Said antistatic agents include, for example, cationic compounds (quaternary ammonium, phosphonium or sulfonium salts), anionic compounds (alkylsulfonates, alkyl sulfates, alkyl phosphates, carboxylates in the form of alkali or alkaline earth metal salts), non-ionic compounds (polyethylene glycol esters, polyethylene glycol ethers, fatty acid esters, ethoxylated fatty amines) and polyol derivatives; preferably they are non-ionic compounds, more preferably they are selected from polyethylene glycol esters, polyethylene glycol ethers, fatty acid esters, polyalkylene ethers, ethoxylated fatty amines and polyol derivatives, and yet more preferably they are polyethylene ethers.

(57) Said UV stabilizers include, for example, benzotriazoles and Hindered Amine Light Stabilizer (HALS).

(58) Said mould release agents include, for example, silicone-based release agents magnesium stearates, calcium stearates, zinc stearate and magnesium oxides; preferably they are magnesium stearates, magnesium oxides, silicone-based release agents or mixtures thereof, more preferably they are silicone-based release agent, magnesium stearate, or mixtures thereof, and yet more preferably they are a combination of magnesium stearate and a silicone based release agent.

(59) Those additives are well known by the skilled person and are available commercially. Light stabilizers and antioxidants are offered under, for example, the trade names IRGANOX, IRGAFOS, TINUVIN (BASF). Releasing agents are available, for example, under the tradenames KEMILUB (UNDESA) and WACKER AK (Wacker).

(60) The thermoplastic composition of the invention can include further colorants, pigments and mineral fillers to obtain coloured articles. It can be included, for example, carbon black, calcium carbonate, iron oxides, or mixtures thereof. Generally the amount of colorant or pigments is comprised from 0.1 to 5 wt. %, preferably from 0.5 to 4 wt. %, and more preferably 1 to 3 wt. %.

(61) Process for Preparing the Thermoplastic Composition

(62) The process for preparing the thermoplastic composition of the invention is simple and can be carried out in standard industrial equipment, such as screw machine for extrusion granulation. For example, that process can include, for example, the mixing of the components in a high speed mixer for a period of time enough to get a homogeneous distribution, e.g. 1-10 min, then the mixture is fed in a screw machine at a speed between 100 and 400 rpm, maintaining the melt temperature below about 200 C. to avoid fibre degradation. The compounding step is generally carried out at a temperature comprised between 170 and 210 C.

(63) Processing of the Thermoplastic Composition

(64) The processing of the thermoplastic composition can be carried out using conventional processing equipment and includes, for example, processing by injection moulding, sheet extrusion with subsequent thermoforming, calendaring and 3D printing.

(65) The injection process using the thermoplastic composition of the invention can achieve a temperature of about 220 C. using high speed and pressure. Under such circumstances, no product degradation is shown. It forms also part of the object of the present invention a moulded article prepared from the thermoplastic composition of the invention.

(66) It forms also part of the object of the present invention the use of the thermoplastic composition of the invention in extrusion, injection, compression moulding and 3D printing.

(67) The thermoplastic composition of the invention shows the following advantages.

(68) It has well-balanced mechanical and thermal properties as shown in Example 10, which provide capacity to be processed and used in a wide range of applications. This balance between high stiffness and heat resistance with an optimized impact resistance/flow ability ratio that makes it suitable to be used in different processing methods such as extrusion and injection.

(69) Surprisingly, articles obtained from the thermoplastic composition in a single stage process show an improved homogeneity of the distribution of the fibre giving better technical performance in terms of mechanical and thermal properties and the use of a specific amount of titanium dioxide allowed an improvement of the surface appearance in comparison to other natural fibre reinforced composites. The improvement of the surface appearance extends its application to objects that remain visible in the final use, without needing any further surface treatment.

(70) The use of natural fibres in thermoplastic compositions is gaining preference over glass fibres and carbon filler due to their low cost and low-weigh characteristics.

(71) The thermoplastic composition is suitable to be used in injection moulding applications; additionally, it can be used on complex moulds and even for thin walled parts.

(72) The thermoplastic composition of the invention is suitable for use in 3-D printing applications with homogenous distribution of the natural fibre over the whole polymer and obtaining articles with excellent surface appearance as shown in the FIGURE.

(73) The thermoplastic composition is suitable to incorporate different pigments in order to obtain a coloured article with an excellent surface finishing without the need of any additional surface treatment.

(74) The invention comprises the following embodiments:

(75) 1.Thermoplastic composition comprising: 1) an acrylonitrile-butadiene-styrene (ABS) polymer, 2) natural fibres, 3) a compatibilizing polymer, and 4) processing aids comprising a lubricant and titanium dioxide, wherein the amount of titanium dioxide is comprised from 1 to 10 wt. %.

(76) 2.Thermoplastic composition according to embodiment 1, wherein the amount of ABS polymer is comprised from 40 to 90 wt. %.

(77) 3.Thermoplastic composition according to embodiment 1, wherein the ABS polymer comprises at least one grafted ABS polymer, with a glass transition temperature Tg<0 C.

(78) 4.Thermoplastic composition according to embodiment 3, wherein the content of grafted ABS polymer is comprised from 15 to 70 wt. %.

(79) 5.Thermoplastic composition according to embodiment 3, wherein it comprises additionally at least one rubber-free copolymer.

(80) 6.Thermoplastic composition according to embodiment 5, wherein the content of rubber-free polymer is comprised from 25 to 65 wt. %.

(81) 7.Thermoplastic composition according to any one of embodiments 3 to 6, wherein the grafted ABS is obtainable by bulk polymerization process containing at least 50 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of from 3 to 50 parts of a butadiene polymer.

(82) 8.Thermoplastic composition according to any one of embodiments 3 to 6, wherein the grafted ABS is obtainable by emulsion polymerization process containing at least 25 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of not more than 75 parts a butadiene polymer.

(83) 9.Thermoplastic composition according to embodiment 8, wherein the grafted ABS is obtainable by emulsion polymerization process containing at least 40 parts of a grafted vinyl aromatic compound and vinyl cyanide compound in a weight ratio of 90:10 to 50:50, preferably styrene and acrylonitrile, in the presence of at least 50 parts of a butadiene polymer.

(84) 10.Thermoplastic composition according to embodiment 9, wherein the butadiene polymer contains an average particle diameter d.sub.50 from 50 to 600 nm.

(85) 11.Thermoplastic composition according to embodiment 10, wherein the butadiene polymer contains particle populations showing an average particle diameter d.sub.50 selected from 50 to 200 nm; from 220 to 340 nm; and from 340 nm to 480 nm.

(86) 12.Thermoplastic composition according to embodiments 10 or 11, wherein the butadiene polymer contains from 35 to 97 (wt. %).sup.1 of gel.

(87) 13.Thermoplastic composition according to embodiment 5, wherein the rubber-free copolymer is comprised of styrene and acrylonitrile in a weight ratio of from 90:10 to 50:50.

(88) 14.Thermoplastic composition according to embodiment 13, wherein the rubber-free copolymer is comprised of styrene and acrylonitrile in a weight ratio of from 73:27.

(89) 15.Thermoplastic composition according to any of embodiments 1 to 14, wherein the natural fibres are cellulose based natural fibres or wood fibres.

(90) 16.Thermoplastic composition according to embodiment 15, wherein the natural fibres are thermo-mechanically treated wood fibres.

(91) 17.Thermoplastic composition according to any of embodiments 1 to 16, wherein the compatibilizing polymer is a polymer with a reactive group selected from the group consisting of epoxy group, N-phenylmaleimide group and maleic anhydride group.

(92) 18.Thermoplastic composition according to embodiment 17, wherein the compatibilizer is a polymer, which includes any of the following monomers glycidyl methacrylate, maleic anhydride, N-phenylmaleimide, and mixtures thereof in combination with styrene or -methylstyrene.

(93) 19.Thermoplastic composition according to embodiment 18, wherein the compatibilizer is a copolymer of styrene and maleic anhydride or a copolymer of styrene, maleic anhydride and N-phenylmaleimide.

(94) 20.Thermoplastic composition according to any of embodiments 1 to 19, wherein the amount of compatibilizing polymer in the thermoplastic composition is from 1 to 10 wt. %.

(95) 21.Thermoplastic composition according to any of claims 1 to 20, wherein the lubricant is selected from the group consisting of stearates, paraffin oils, polyethylene waxes, lauric acid, palmitic acid, stearic acid, stearic acid amides, ethylenediamine, glycerol, and mixtures thereof.

(96) 22.Thermoplastic composition according to embodiment 21, wherein the lubricant is ethylene bis stearamide.

(97) 23.Thermoplastic composition according to embodiment 22, wherein the amount of lubricant in the thermoplastic composition is from 1 to 5 wt. %.

(98) 24.Thermoplastic composition according to any of embodiments 1 to 23, wherein it further comprises antioxidants, antistatic agents, mould releasing agents, colorants, pigments, mineral fillers, visible light and UV stabilizers, and mixtures thereof.

(99) 25.Thermoplastic composition according to embodiment 24, wherein it comprises carbon black, calcium carbonate, iron oxides, or mixtures thereof.

(100) 26.A moulded article prepared from the thermoplastic composition of any one of embodiments 1 to 25.

(101) 27.Use of the thermoplastic composition of any one of embodiments 1 to 25 in extrusion, injection, compression moulding and 3D printing.

(102) Next, several examples of the invention are provided for illustrative purposes.

EXAMPLES

Examples 1-8 and Comparative Example: ABS Thermoplastic Compositions

(103) The components listed in the Table 1 were premixed in a high speed in a turbo-mixer for 5 minutes and then placed in a twin screw machine, at 400 rpm of rotational speed of 400 rpm and at a temperature of 200 C., to obtain the thermoplastic composition by extrusion granulation. Amounts in the table are expressed in parts by weight:

(104) TABLE-US-00002 TABLE 1 Example Component 1 2 3 4 5 6 7 8 Comp. A.1.1-1 27.84 27.84 27.84 27.84 27.84 25.73 23.91 A.1.1-2 26.00 A.1.1-3 23.34 A.2 42.44 44.76 42.44 42.44 42.44 40.44 38.80 46.94 50.81 B-1 22.02 22.02 22.02 22.02 22.02 22.02 22.00 B-2 22.02 22.02 C-1 3 3 5 7.97 3 3 C-2 3 C-3 3 C-4 3 D 2 1.65 2 2 2 2 2 2 2 E 2.22 1.42 2.22 2.22 2.22 2.22 2.22 2.22 2.22 Other 0.48 1.15 0.48 0.48 0.48 0.48 1.28 0.48 0.48 additives

(105) The following components were used in the previous examples 1-8: Component A.1.1-1=Grafted ABS polymer produced by emulsion polymerization with a butadiene content between 51-54 wt. % commercially available under the trade name ELIX 152I (ELIX Polymers). Component A.1.1-2=Grafted ABS polymer produced by emulsion polymerization with a butadiene content between 54-58 wt. % commercially available under the trade name ELIX 158I (ELIX Polymers). Component A.1.1-3=Mono-modal grafted ABS polymer produced by emulsion polymerization with a butadiene content between 50-60 wt. % commercially available under the trade name KUMHO HR181 (Korea Kumho Petrochemical). Component A.2: SAN polymer showing a molecular weight of 105,000, wherein the styrene:acrylonitrile ratio is 73:27, commercially available under the trade name ELIX 230G (ELIX Polymers). Component B-1: Wood fibres thermo-mechanically treated, commercially available under the trade name Woodforce Natural FAST (Sonae Industria). Component B-2: Wood fibres thermo-mechanically treated, commercially available under the trade name Woodforce Black FAST (Sonae Industria). Component C-1=SMA polymer showing a molecular weight of 110,000, MAH content of 23 wt. %, commercially available under the trade name XIRAN SZ23110 (Polyscope Polymers). Component C-2=SMA polymer showing a molecular weight of 120,000, MAH content of 26 wt. %, commercially available under the trade name XIRAN SZ26120 (Polyscope Polymers). Component C-3: SMI polymer showing a molecular weight of 145,000, MAH content of 10 wt. %, N-PMI content of 18 wt. %, commercially available under the trade name XIRAN IZ1018M (Polyscope Polymers). Component C-4: SMI polymer showing a molecular weight of 150,000, MAH content of 7 wt. %, N-PMI content of 21 wt. %, commercially available under the trade name XIRAN 0721M (Polyscope Polymers). Component D: ethylene bis stearamide (EBS). Component E: Titanium dioxide, commercially available under the trade name TRONOX CR-470 (Tronox). Other additives: antioxidants, releasing agents, UV stabilizers, which are already well known to the skilled person.

(106) Comparative example has been prepared according to an analogous process as Examples 1 to 8, but it does not include component E.

Example 9

Mechanical Testing of ABS Thermoplastic Compositions

(107) Thermoplastic compositions according to examples 1-8 were tested performing the following tests: Tensile Strength test: in accordance with ISO 527-1, -2 standard test, tensile speed of 50 mm/min. Units: MPa. Izod Notched Impact Strength: according to ISO 180 standard test. Units: KJ/m2. Vicat B120: according to the ISO 306 standard test; 120 C./h. Units: C. Melt Volume Rate (MVR): according to the ISO 1133-1 standard test; 220 C., 10 Kg. Units: cm.sup.3/10

(108) In Table 2, mechanical properties of the thermoplastic compositions of examples 1-9 are shown:

(109) TABLE-US-00003 TABLE 2 Example Parameter 1 2 3 4 5 6 7 8 Comp. Tensile 51.42 47.05 49.08 49.03 48.43 50.20 52.19 46.90 50.7 Strength IZOD 6.5 3.7 3.8 3.6 4 3.7 3.7 3.6 4.2 Impact VICAT 100.4 103.8 103.3 102.0 103.3 105.8 101.9 97.4 B120 MVR 7.08 7.35 9.47 8.51 5.03 5.79 5.96 10.2

(110) The thermoplastic compositions of examples 1 to 8 showed a good balance between toughness (Izod notched impact >3.5 MPa) and fluidity (MVR, 220 C., 10 Kg, cm.sup.3/10=>5) and tensile strength (about 50 MPa) with stiffness and thermal properties (softening point, Vicat B120 >100 C.). These material compositions are suitable for injection moulding and extrusion process.

(111) When these thermoplastic compositions were extruded/injected, moulded parts showed an excellent surface appearance as shown in the FIGURE, where the composition of Example 2, in part (A) of the FIGURE, and the composition of Comparative example, in part (B) of the FIGURE, were injected. It can be seen that the former shows an excellent surface finishing, whereas the latter shows marks distributed over the entire surface.