WO2015091416A1

WO2015091416A1 - Polyamide-polyester blends with improved properties

Info

Publication number: WO2015091416A1
Application number: PCT/EP2014/077864
Authority: WO
Inventors: Suresh R. Sriram
Original assignee: Solvay Specialty Polymers Usa, Llc
Priority date: 2013-12-20
Filing date: 2014-12-16
Publication date: 2015-06-25

Abstract

The present invention relates to certain polyamide-polyester blends and more particularly to certain polymer compositions (C) comprising from 30 to 50 wt. % of a poly(m-xylylene adipamide), from 5 to 20 wt. % of poly(butylene terephthalate), and from 10 to 60 wt. % of a reinforcing filler, based on the total weight of the polymer composition (C). Such compositions present very good and balanced properties which make them very well suited for the manufacture of thin parts of mobile electronic devices.

Description

Polyamide-polyester blends with improved properties

This application claims priority to U.S. provisional application

No. 61/919262 filed December 20, 2014, the whole content of this application being incorporated herein by reference for all purposes.

Field of the invention

The present invention relates to certain polyamide-polyester blends and more particularly to certain polymer compositions comprising poly(m-xylylene adipamide) (hereinafter PMXD6 polymer), poly(butylene terephthalate)

(hereinafter PBT polymer) and reinforcing fillers suited for the manufacture of thin parts of mobile electronic devices.

Background of the invention

Electronic devices, and in particular mobile electronic devices, such as mobile telephones, personal digital assistants, laptop computers, tablet computers, global positioning system receivers, portable games, radios, cameras and camera accessories, and the like are becoming increasingly widely used in many different environments. It is often important that the parts of such devices be made from materials that are easy to process into various end-use articles, are able to withstand the rigors of frequent use of such articles and can meet challenging aesthetic demands while not interfering with their intended operability. It is often desirable that such materials have good impact resistance, flame resistance, moisture resistance, tensile strength, stiffness and that they exhibit minimal warpage and low flash when they are formed (as by injection molding, for example) into the end use articles or parts of articles.

The warpage is a term designating dimensional distortion in the molded parts leading to their concave or convex curvature. An inherent shrinkage occurs during any injection molding process because the density of the polymer varies from the processing temperature to the ambient temperature. During injection molding, the variation in shrinkage creates internal stresses which lead to the warpage of the part upon ejection from the mold. If the shrinkage throughout the part is uniform, the molded part will not deform or warp, it will simply become smaller. However, achieving low and uniform shrinkage is a complicated task due to the presence and interaction of many factors such as molecular and fiber orientations, mold cooling, part and mold designs, and process conditions. Flash formation in thermoplastics is another one of the major problems encountered during injection molding. Flash is referring to polymer that has flowed into the space between the split halves of the mold cavity and then solidified resulting in excess material exceeding the normal shape of the molded part.

Aromatic polyamides feature a set of superior properties which have been recognized in a variety of demanding applications for many years. Among aromatic polyamides, PMXD6's exceptional properties such as high stiffness, superior strength, good surface aesthetics and low moisture absorption (when compared to other polyamides) have made of it an excellent candidate for the manufacture of articles such as electronic device housings, and in particular mobile electronic device housings such as mobile phone housings. The use of PMXD6 taken alone comes unfortunately with a few drawbacks such as a too low impact resistance and a flash/warpage issue, which makes their use as such not suitable for certain demanding applications.

On the other hand, polyesters combine excellent mechanical, electrical and thermal properties with very good chemical resistance and dimensional stability. In general, polyesters also offer low moisture absorption and have good flow properties. They are thus widely used in various applications where their specific properties are valued.

Certain blends of polyamides and polyesters have already been described in the past. In particular, small amounts of PMXD6 have been used in polyesters to improve the barrier properties against oxygen of polyesters in applications such as films or bottles used for food packaging.

For example, US 6,933,055 discloses compositions useful as a barrier layer comprising a blend of PET and PMXD6.

US 2013/0089686 relates to a plastic material for packaging applications comprising a composition including among other ingredients 80 to 98.9 wt. % of a polyester and from 1 to 10 wt. % of PMXD6.

JP 2002/069276 discloses also specific PBT-PMXD6 blends for food packaging applications where PBT is present from 40 to 95 wt. %.

JP 2002/127337 relates to transparent stretched polyamide films for packaging applications comprising at least one layer of a 75 to 99 wt. % of a polyamide such as PMXD6 and 1 to 25 wt. % of PBT. In particular, JP' 337 discloses in its example a film comprising one layer of a 85/15 or

a 95/5 PMXD6-PBT blend. There is still a need on the market for a polymer composition suitable for the manufacture of parts of mobile electronic devices presenting all the good properties of PMXD6 (i.e. high stiffness, superior strength, good surface aesthetics and low moisture absorption) while featuring improved impact resistance properties, low flash and low warpage.

The Applicant has found that the incorporation of low amounts of PBT into reinforced PMXD6 compositions surprisingly improves certain mechanical properties (such as elongation at break and impact resistance), reduces the above mentioned warpage and flash issues while substantially maintaining all the advantageous attributes of PMXD6-based compositions.

Summary of the Invention

The present invention relates thus to a polymer composition (C) comprising :

- from 30 to 50 wt. % of a poly(m-xylylene adipamide) (PMXD6 polymer); - from 5 to 20 wt. % of poly(butylene terephthalate) (PBT polymer), and

- from 10 to 60 wt. % of at least one reinforcing filler, based on the total weight of the polymer composition (C).

In a second aspect, the present invention discloses a method for improving the mechanical properties of a reinforced polymer composition (C) comprising from 30 to 50 wt. % of PMXD6 polymer and from 10 to 60 wt. % of a reinforcing filler, based on the total weight of the polymer composition (C), including the step of adding from 5 to 20 wt. % of PBT polymer, based on the total weight of the polymer composition (C).

In a third aspect, the present invention relates to a method for the manufacture of the polymer composition (C).

In a fourth aspect, the present invention relates to an article comprising the above mentioned polymer composition (C) and in particular to a part of a mobile electronic devices comprising the same.

Finally, the invention also pertains to a method for the manufacture of the above part of said mobile electronic device including the step of injection molding the above mentioned polymer composition (C).

Detailed Description of the Invention

The polymer composition (C) of the present invention comprises three essential ingredients that are described in detail here below : The poly( m-xylylene adipamide)

The polymer composition (C) comprises from 30 to 50 wt. % of a poly(m-xylylene adipamide) (PMXD6 polymer), based on the total weight of the polymer composition (C).

The expressions "poly(m-xylylene adipamide)" and "PMXD6 polymer" as used within the frame of the present invention are intended to denote a polymer comprising recurring units, more than 50 mol. % of which are obtained through the polycondensation of m-xylylene diamine and/or p-xylylene diamine and adipic acid. Preferably, at least 80 mol. % of the recurring units of the polymer are recurring units obtained through the polycondensation of m-xylylene diamine and/or p-xylylene diamine and adipic acid. Even more preferably, the polymer consists essentially of such recurring units.

In a first preferred embodiment, the PMXD6 is a polymer comprising recurring units at least 80 mol. % of the recurring units of which are recurring units obtained through the polycondensation of m-xylylene diamine and adipic acid. Even more preferably, the polymer consists essentially of such recurring units.

In a second preferred embodiment, the PMXD6 is a polymer comprising recurring units, from 10 to 50 mol. , preferably from 20 to 40 mol. % of which are obtained through the polycondensation of m-xylylene diamine and adipic acid and from 50 to 90 mol. , preferably from 60 to 80 mol. , of which are obtained through the polycondensation of p-xylylene diamine and adipic acid.

In a third preferred embodiment, the PMXD6 is a polymer comprising recurring units, from 40 to 80 mol. , preferably 50 to 70 mol. % of which are obtained through the polycondensation of m-xylylene diamine and adipic acid and from 20 to 60 mol. , preferably from 30 to 50 mol. % of which are obtained through the polycondensation of p-xylylene diamine and adipic acid.

Excellent results were obtained when using the PMXD6 polymer obtained through the polycondensation of adipic acid with meta-xylylene diamine and optionally p-xylylene diamine, which are notably commercially available as IXEF^® polyarylamides from Solvay Specialty Polymers U.S. A, L.L.C..

The PMXD6 polymer is preferably present in an amount of at least 31, more preferably at least 32, still more preferably at least 33, most preferably at least 34 wt. , based on the total weight of the polymer composition (C). The PMXD6 polymer is also preferably present in an amount of at most 48, more preferably at most 46, still more preferably at most 44, most preferably at most 42 wt. , based on the total weight of the polymer composition (C).

Excellent results were obtained when the PMXD6 polymer was present in an amount of from 32 to 42 wt. , based on the total weight of the polymer composition (C).

The poly(butylene terephthalate)

The polymer composition (C) comprises also from 5 to 20 wt. % of poly(butylene terephthalate) (PBT polymer), based on the total weight of the polymer composition (C).

The expressions "poly(butylene terephthalate)" and "PBT polymer"as used within the frame of the present invention are intented to denote a polymer comprising recurring units, more than 50 mol. % of which are obtained through the polymerization of butanediol and terephthalic acid. Preferably, at least 80 mol. % of the recurring units of the polymer are recurring units obtained through the polymerization of butanediol and terephthalic acid. Even more preferably, the polymer consists essentially of such recurring units.

The PBT polymer is preferably present in an amount of at least 6, more preferably at least 7, still more preferably at least 8, most preferably at least 9 wt. , based on the total weight of the polymer composition (C). The PBT polymer is also preferably present in an amount of at most 19, more preferably at most 18, still more preferably at most 17, most preferably at most 16 wt. , based on the total weight of the polymer composition (C).

Excellent results were obtained when the PBT polymer was present in an amount of from 9 to 16 wt. , based on the total weight of the polymer composition (C). The reinforcing filler

Finally, the polymer composition (C) comprises from 10 to 60 wt. % of at least one reinforcing filler, based on the total weight of the polymer

composition (C).

Reinforcing fillers may be particulate or fibrous. They are preferably fibrous. More preferably, the reinforcing filler is selected from glass fibers, carbon fibers, synthetic polymeric fibers, aramid fibers, aluminum fibers, titanium fibers, magnesium fibers, boron carbide fibers, rock wool fibers, steel fibers, woUastonite, etc. Still more preferably, it is selected from glass fibers and woUastonite. Most preferably, the reinforcing filler is glass fibers. The term glass fibers include chopped of strand A-, E-, C-, D-, S- T- and R-glass fibers, as described in chapter 5.2.3, p. 43-48 of Additives for Plastics Handbook, 2nd ed., John Murphy. Glass fibers may have a round cross- section or an elliptic cross- section (also called flat fibers).

The reinforcing filler is preferably present in an amount of at least 15, more preferably at least 20, still more preferably at least 25, most preferably at least 30 wt. , based on the total weight of the polymer composition (C). The reinforcing filler is also preferably present in an amount of at most 59, more preferably at most 58, still more preferably at most 57, most preferably at most 55 wt. , based on the total weight of the polymer composition (C).

Excellent results were obtained when the reinforcing filler was present in an amount of from 45 to 55 wt. , based on the total weight of the polymer composition (C).

Optional ingredients

The polymer composition (C) of the present invention may also comprise other optional ingredients such as a halogen free flame retardant.

Halogen free flame retardants may thus also be present in the polymer composition (C) and are well known in the art. As halogen free flame retardants, the polymer composition (C) may notably comprise at least one

organophosphorous compound selected from the group consisting of phosphinic salts (phosphinates), diphosphinic salts (diphosphinates) and condensation products thereof. Preferably, the organophosphorous compound is selected from the group consisting of phosphinic salt (phosphinate) of the formula (I), a diphosphinic salt (diphosphinate) of the formula (II) and condensation products thereof :

wherein : Ri, R₂ are identical or different and each of Ri and R₂ is a hydrogen or a linear or branched C1-C6 alkyl group or an aryl group; R₃ is a linear or branched CI -CIO alkylene group, a C6-C10 arylene group, an alkyl- arylene group, or an aryl-alkylene group; M is selected from calcium ions, magnesium ions, aluminum ions, zinc ions, titanium ions, and combinations thereof; m is an integer of 2 or 3; n is an integer of 1 or 3; and x is an integer of 1 or 2.

Preferably, Ri and R₂ are independently selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, n-pentyl, and phenyl; R₃ is selected from methylene, ethylene, n-propylene, isopropylene, n-butylene, tert-butylene, n-pentylene, n-octylene, n-dodecylene, phenylene, naphthylene,

methylphenylene, ethylphenylene, tert-butylphenylene, methylnaphthylene, ethylnaphthylene, tert-butylnaphthylene, phenylmethylene, phenylethylene, phenylpropylene, and phenylbutylene; and M is selected from aluminum and zinc ions.

Phosphinates are preferred as organophosphorous compound. Suitable phosphinates have been described in US 6,365,071. Particularly preferred phosphinates are aluminum phosphinates, calcium phosphinates, and zinc phosphinates. Excellent results were obtained with aluminum phosphinates. Among aluminum phosphinates, aluminium ethylmethylphosphinate and aluminium diethylphosphinate and combinations thereof are preferred. Excellent results were in particular obtained when aluminium diethylphosphinate was used.

The polymer composition (C) of the present invention comprises advantageously from 0 to 20 wt. % of a halogen free flame retardant, based on the total weight of the polymer composition (C). When present, the halogen free flame retardant is comprised in the polymer composition (C) in an amount of preferably at least 1 wt. , more preferably of at least 5 wt. , still more preferably of at least 10 wt. % and most preferably of at least 15 wt. , based on the total weight of the polymer composition (C). Besides, if present, the halogen free flame retardant is preferably comprised in the polymer composition (C) in an amount of at most 25 wt. , more preferably of at most 23 wt. , still more preferably of at most 20 wt. % and most preferably of at most 18 wt. , based on the total weight of the polymer composition (C).

The polymer composition (C) may also comprise, in addition to the halogen free flame retardant, a flame retardant synergist (FRS-A), preferably phosphorus and/or nitrogen-containing synergists. Indeed, synergistic combinations of phosphinates with nitrogen-containing compounds, known to have more effective action than the phosphinates alone in many polymers (see e.g. US 6,365,071, US 6,207,736, US 6,509,401) are also in accordance with the invention. The flame retardant synergist (FRS-A) preferably comprise benzoguanamine, tris(hydroxyethyl) isocyanurate, allantoin, glycoluril, melamine, melamine cyanurate, dicyandiamide, guanidine, carbodiimides, and condensation products thereof. The flame retardant synergist (FRS-A) preferably comprise condensation products of melamine. By way of example, condensation products of melamine are melem, melam, or melon, or compounds of this type with a higher condensation level, or else a mixture of the same, and, by way of example, may be prepared by the process described in US 5,985,960.

The polymer composition (C) may also comprise, in addition to the halogenated flame retardant system, a flame retardant synergist (FRS-B), different from the flame retardant synergist (FRS-A). The flame retardant synergist (FRS-B) may comprise antimony trioxide, antimony dioxide, sodium antimonate, iron oxide, zinc phosphate and/or a metal salt of boric acid or stannic acid, wherein said metal is selected from the group consisting of zinc, an alkali metal (metal of group I of the Periodic Table) and an alkaline earth metal (metal of group II of the Periodic Table). Suitable metal salts of stannic acid include, for example, zinc stannate, zinc hydro xystannate, magnesium stannate, sodium stannate and potassium stannate. Suitable metal salts of boric acid include, for example, zinc borate, calcium borate and magnesium borate. Of these metal salts, zinc borate and zinc stannate, and mixtures thereof are preferred. More preferably, polymer composition (C) comprises sodium antimonate and/or zinc borate.

When present, the flame retardant synergist (FRS-A) is preferably comprised in the polymer composition (C) in an amount of 0.1-10 wt. , more preferably 0.5-8 wt. , still more preferably 1-5 wt. , relative to the total weight of the polymer composition (C).

When present, the flame retardant synergist (FRS-B) is preferably comprised in the polymer composition (C) in an amount of 0.1-20 wt. , more preferably 1-15 wt. , still more preferably 5-10 wt. , relative to the total weight of the polymer composition (C).

The polymer composition (C) may also comprise other polymers than the above mentioned PMXD6 polymer and PBT polymer such as polyamides

(notably PA6,6, PA9T, PA10T and PA12T) polycarbonate, polyethylene glycol, polyolefins, polysulfone, PEEK and PTFE.

The polymer composition (C) can further contain one or more impact modifiers. The impact modifiers can be reactive with the PMXD6 polymer and/or with the PBT polymer or can be non-reactive. In certain specific embodiment, the polymer composition (C) contains at least one reactive impact modifier and at least one non-reactive impact modifier.

Reactive impact modifiers that may be used include ethylene- maleic anhydride copolymers, ethylene- alkyl (meth)acrylate-maleic anhydride copolymers, ethylene- alkyl (meth)acrylate-glycidyl (meth)acrylate copolymers, and the like. An example of such reactive impact modifier is a random

terpolymer of ethylene, methylacrylate and glycidyl methacrylate.

Non-reactive impact modifiers that may be blended into the polymer composition (C) generally include various rubber materials, such as acrylic rubbers, ASA rubbers, diene rubbers, organosiloxane rubbers, EPDM rubbers, SBS or SEBS rubbers, ABS rubbers, NBS rubbers and the like. Particular examples of non-reactive impact modifiers include ethyl butylacrylate, ethyl (methyl)acrylate or 2 ethyl hexyl acrylate copolymers.

If present, the impact modifier is preferably comprised in the polymer composition (C) in an amount of at least 2 wt. , more preferably at

least 4 wt. , still more preferably at least 5 wt. , and most preferably at least 10 wt. , based on the total weight of the polymer composition (C). When present, the impact modifier is also preferably comprised in the polymer composition (C) in an amount of at most 20 wt. , more preferably at

most 15 wt. , still more preferably at most 10 wt. , and most preferably at most 5 wt. , based on the total weight of the polymer composition (C).

The polymer composition (C) may optionally further contain up to about 3 wt. % of ultraviolet light stabilizers or UV blockers, based on the total weight of the polymer composition (C). Examples include triazoles and triazines, oxanilides, hydroxybenzophenones, benzoates, and a-cyanoacrylates. When present, the ultraviolet light stabilizers are preferably comprised in the polymer composition (C) in an amount of about 0.1 to about 3 wt. , or preferably about 0.1 to about 1 wt. , or more preferably about 0.1 to about 0.6 wt. , of the total weight of the polymer composition (C).

The polymer composition (C) may also comprise other optional ingredients such as mold release agents, lubricants, nucleating agents, fillers, plasticizers, optical brighteners and other stabilizers, different from the ones described above.

In particular, the polymer composition (C) may comprise a nucleating agent. When present, the nucleating agent is preferably comprised in the polymer composition (C) in an amount of about 0.5 to about 3 wt. , or more preferably of about 0.8 to about 1.2 wt. , and most preferably of about 1 wt. , of the total weight of the polymer composition (C).

The nucleating agent may be advantageously selected from the group consisting of talc, silica, talc, clay, alumina, mica, zirconia, tin oxide, tin indium oxide, antimony tin oxide, kaolin, calcium silicate, calcium carbonate, magnesium carbonate, zeolites, and the like. Excellent results were obtained when talc was used as nucleating agent.

In a second aspect, the present invention relates to a method for improving the mechanical properties of a reinforced polymer composition (C) comprising from 30 to 50 wt. % of PMXD6 polymer and from 10 to 60 wt. % of a reinforcing filler, based on the total weight of the polymer composition (C), including the step of adding from 5 to 20 wt. % of PBT polymer, based on the total weight of the polymer composition (C).

In a third aspect, the present invention relates to a method for the manufacture of the polymer composition (C). Any melt-mixing method may be used to combine the ingredients to prepare the polymer composition (C). For example, the different ingredients may be added to a melt mixer, such as, for example, a single or twin-screw extruder, a blender or a Banbury mixer, either all at once through a single step addition, or in a stepwise fashion, and then melt- mixed. When adding the ingredients in a stepwise fashion, part of them are first added and melt-mixed with the remaining ingredients are subsequently added and further melt-mixed until a well-mixed composition is obtained.

In a fourth aspect, the present invention relates to an article comprising the above mentioned polymer composition (C) and in particular to a part of an articles used in an electric/electronic application.

In a preferred embodiment, the article according to the present invention is a part of a mobile electronic device.

The term "mobile electronic device" is intended to denote an electronic device that is designed to be conveniently transported and used in various locations. Representative examples of mobile electronic devices include mobile phones, personal digital assistants, laptop computers, tablet computers, radios, cameras and camera accessories, watches, calculators, music players, global positioning system receivers, portable games, hard drives and other electronic storage devices, and the like.

The part of the mobile electronic device according to the present invention may be selected from a large list of articles such as fitting parts, snap fit parts, mutually moveable parts, functional elements, operating elements, tracking elements, adjustment elements, carrier elements, frame elements, switches, connectors and housings. In particular, the polymer composition (C) is very well suited for the production of housing parts of mobile electronic device.

Therefore, the part of the mobile electronic device according to the present invention is advantageously a mobile electronic device housing. By "mobile electronic device housing" is meant one or more of the back cover, front cover, antenna housing, frame and/or backbone of a mobile electronic device. The housing may be a single article or comprise two or more components. By "backbone" is meant a structural component onto which other components of the device, such as electronics, microprocessors, screens, keyboards and keypads, antennas, battery sockets, and the like are mounted. The backbone may be an interior component that is not visible or only partially visible from the exterior of the mobile electronic device. The housing may provide protection for internal components of the device from impact and contamination and/or damage from environmental agents (such as liquids, dust, and the like). Housing components such as covers may also provide substantial or primary structural support for and protection against impact of certain components having exposure to the exterior of the device such as screens and/or antennas.

In a preferred embodiment, the mobile electronic device housing is selected from the group consisting of a mobile phone housing, a tablet housing, a laptop computer housing and a tablet computer housing. Excellent results were obtained when the part of the mobile electronic device according to the present invention was a mobile phone housing.

The part of the mobile electronic device according to the present invention is advantageously characterized by a thickness of a flat portion of said part being 0.9 mm or less, preferably 0.8 mm or less, more preferably 0.7 mm or less, still more preferably 0.6 mm or less and most preferably 0.5 mm or less on average. The term "on average" is herein intended to denote the average thickness of the part based on the measurement of its thickness on at least 3 points of at least one of its flat portions.

Another objective of the present invention is to provide a method for the manufacture of the above described mobile electronic device comprising at least one part comprising the polymer composition (C), said method including the steps of :

- providing as components at least a circuit board, a screen and a battery; - providing at least one part comprising the polymer composition (C);

- assembling at least one of said components with said part or mounting at least one of said components on said part.

Further, the invention also pertains to a method for the manufacture of the above part of said mobile electronic device, including the step of injection molding the above mentioned polymer composition (C). Such method is not specifically limited. The polymer composition (C) may be generally processed by injection molding, extrusion or other shaping technologies. It preferably comprises the injection molding of the polymer composition (C). Thus, the method for the manufacture of the above described part of a mobile electronic device includes preferably the step of injection molding and solidification of the polymer composition (C).

Mobile electronic devices are very often commercialized in a black color. However, there is a growing market interest in colored mobile electronic devices. The present invention allows the manufacture of colored mobile electronic device, and in particular colored mobile electronic device housings.

The above described method for the manufacture of the mobile electronic device may thus further include an additional step of painting or coating said part comprising the polymer composition (C).

Excellent results were obtained when the mobile electronic device was first painted with a primer coating paint and then with a top coating paint. These coatings gave surprisingly excellent results in adhesion tests. In addition, the present invention provides the great benefit that the polymer composition (C) has an excellent colorability using the above described pigments and also an excellent paintability using the above mentioned paints.

In another preferred embodiment, the article according to the present invention is an electric or electronic part selected from the group consisting of electrical connectors, (such as cable connectors, single point connectors, male and female connectors, blade connectors, circular connectors, minibridges, maxibridges, pin headers, plug and socket connectors, male and female USB connectors), circuit breaker housings, battery housings and solenoid housings. It is preferably a circuit breaker housing or a solenoid housing.

Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence. The present invention is intended to be explained in more detail with reference to the subsequent examples without wishing to restrict the latter by the special embodiments shown here.

EXAMPLES

The disclosure will now be illustrated with working examples, which are intended to illustrate the present invention and are not intended to restrictively imply any limitations on the scope of the present disclosure.

The following commercially available materials were used :

PMXD6 polymer : IXEF^® PARA from Solvay Specialty Polymers U.S.A, L.L.C. PBT polymer : Celanex^® PBT 1400A NAT from Celanese Corporation

Glass fibers : CSG 3PA 820 from FRP Services & Co (America) Inc. NY.

PA 6,6 : STAB AMID^® Nylon 66 27 AE1 from Solvay Polyamide &

Intermediates.

Lubricant : Calcium stearate from Nexeo Solutions.

Additive package : IRGANOX^® B 1171 from BASF Corporation

Nucleating agent : Steamic Talc from Imerys Talc Luzenac Company, France. General procedure for the preparation of the compositions

The PMXD6 and PBT polymers described above as well as the other ingredients listed in Table 1 (except the glass fibers) were fed to the first barrel of a ZSK-26 twin screw extruder comprising 12 zones via a loss in weight feeder. The barrel set-point temperatures were in the range of 250-330°C and the resins were melted before zone 5. The glass fibers were fed at zone 5 through a side stuffer via a loss in weight feeder. The screw rate was 250 rpm. The extrudates were cooled and pelletized using conventional equipment. The nature and quantity of the various ingredients used are summarized in Table 1, indicating the amount of each ingredient in wt. %.

Table 1 : Nature and quantity of the ingredients used

The presence of PA 6,6 and talc in CE-1 is necessary to reach good crystallization levels and therefore the best mechanical and thermal properties of the compound.

Mechanical Properties of the compounds

The pellets obtained as above described were molded into tensile bars as per ISO molding procedures. Compounds of examples E-l and E-2 were easier to mold and had significantly lower injection pressure (about 20-30 % lower) when compared to the compound of example CE-1. The parts made from the compounds of E-l and E-2 also featured a smooth surface appearance.

The ISO bars were then tested for tensile and impact properties as per ISO testing standards. The mechanical properties of the examples and comparative examples are summarized in the Table 2.

The mechanical properties of the compounds according to the invention were excellent and in particular the Notched Izod values were significantly greater than the ones obtained for CE-1 and CE-2. Good strength and stiffness were observed for the compounds according to the present invention when compared to 50 % glass filed compounds of CE-1 and CE-2.

In addition to the mechanical properties, the heat deflection

temperatures (HDT) of the compounds according to the present invention were greater than the value obtained for CE-1 or CE-2 (see Table 2). Finally, the moisture absorptions of the compounds of E-l and E-2 were lower than the compound of CE-1 despite the fact that MXD6 was the main resin component. Table 2 : Properties of the compositions obtained

Warpage and flash behavior of the compounds

In addition to the above detailed properties, the warpage and flash performance of the obtained compounds were also evaluated. The warpage was measured on the standard ISO 60x60x2mm plaques and the shrinkage of the molded of the plaque was evaluated using a microscope as per ISO procedure by measuring the distance between the cross hatches on the plaques in the flow and transverse flow directions. As general rule, it is widely acknowledged in this field that a direct correlation between the shrinkage anisotropy and the warpage of molded product exists. Compounds of examples E-l and E-2 were found to possess almost 50 % lower shrinkage in the transverse direction when compared the compounds of CE-1 and CE-2. The results of the shrinkage test are summarized in Table 3.

Table 3 : Shrinkage and flash properties of the obtained compositions

The flash performance of the compounds were evaluated by visually inspecting molded parts obtained from the compounds of examples E-l, E-2, CE-1 and CE-2 and observing the material in excess that comes out of the mold using a microscope at the parting line. This visual test is a typical pass or fail type test assessment. Results summarized in Table 3 show that the compounds of example E- 1 and E-2 lead to the lowest amount of shrinkage and lower flash. Compounds of examples E- 1 and E-2 feature thus an outstanding balance of good mechanical properties combined to low warpage and low flash behavior which make them very well suited for the manufacture of thin parts of mobile electronic devices.

Claims

C L A I M S

1. A polymer composition (C) comprising :

- from 30 to 50 wt. % of a poly(m-xylylene adipamide) (PMXD6 polymer);

- from 5 to 20 wt. % of poly(butylene terephthalate) (PBT polymer), and - from 10 to 60 wt. % of at least one reinforcing filler, based on the total weight of the polymer composition (C).

2. The polymer composition (C) according to claim 1, wherein the PMXD6 polymer is present in an amount of from 32 to 42 wt. , based on the total weight of the polymer composition (C).

3. The polymer composition (C) according to anyone of the preceding claims, wherein the PBT polymer is present in an amount of from 9 to 16 wt. , based on the total weight of the polymer composition (C).

4. The polymer composition (C) according to anyone of the preceding claims, wherein the reinforcing filler is present in an amount of from 45 to 55 wt. , based on the total weight of the polymer composition (C).

5. The polymer composition (C) according to anyone of the preceding claims, wherein the reinforcing filler is glass fibers.

6. The polymer composition (C) according to anyone of the preceding claims, further comprising a halogen free flame retardant.

7. The polymer composition (C) according to anyone of the preceding claims, further comprising one or more impact modifiers.

8. The polymer composition (C) according to anyone of the preceding claims, further comprising a nucleating agent.

9. An article comprising the polymer composition (C) according to anyone of claims 1 to 8.

10. The article according to claim 9, wherein it is a part of a mobile electronic device.

11. The article according to claim 10, wherein it is a housing part of mobile electronic device.

12. The article according to claim 9, wherein it is a circuit breaker housing or a solenoid housing.

13. A method for the manufacture of the article of anyone of claims 9 to 12 including the step of injection molding the polymer composition (C) according to anyone of claims 1 to 8.