Patent Description:
Polymer compositions are provided. The polymer compositions have excellent thermal conductivity and include a liquid crystal polymer ("LCP"), a flat glass fiber, and boron nitride and zinc oxide. Articles incorporating the polymer compositions as well as methods of making the polymer composition and articles are also provided.

As the power density of electrical components increases, so does thermal output of the electrical component, at least in part due to the resistance of the current carriers. The result is significantly increased heat accumulation in the electrical component. For example, there is a continuous demand to increase the power density in electric motors for electric vehicles (e.g. automobiles, motorcycles, boats and planes), concomitant with increasing consumer demand for higher performing vehicles. However, as power density increases, so does the heat accumulation in and around the electric motor, which can significantly reduce motor efficiency.

<CIT> (D1) discloses a polymer composition having an in-plane thermal conductivity of about <NUM> W/m-K or more, wherein the composition comprises: <NUM> parts by weight of at leats one aromatic LCP; from about <NUM> to about <NUM> parts by weight of an inorganic material having a hardness value of about <NUM> or more; from about <NUM> to about <NUM> parts by weight of a thermally conductive particulate material having an average size of from about <NUM> to about <NUM> micrometers.

<CIT> (D2) discloses a liquid crystal polymer material reinforced by glass fibers with non-circular cross sections. <CIT> (D3) discloses a thermoplastic resin for light-emitting elements. <NPL> (D4) relates to the progress of liquid crystal polyester (LCP) for <NUM> application.

The polymer composition of the invention is defined in claim <NUM>.

In some embodiments, the polymer composition has a through-plane thermal conductivity of from <NUM> W/m-K to <NUM> W/m-k, as measured according to ASTM E1461-<NUM>. In some embodiments, the polymer composition has a flexural strength of from <NUM> MPa to <NUM> MP, according to ASTM D790. In some embodiments, the polymer composition has a flexural strain of from <NUM> MPa to <NUM> MPa, as measured according to ASTM D790. In some embodiments, the polymer composition has an apparent viscosity of from <NUM> Pa·s to <NUM> Pa·s at shear rate of <NUM>-<NUM>; from <NUM> Pa·s to <NUM> Pa·s at a shear rate of <NUM>-<NUM>; or of from <NUM> Pa·s to <NUM> Pa·s at a shear rate of <NUM>-<NUM>, as measured according to ASTM D3835.

In some embodiments, the polymer composition is free of round glass fibers.

Described herein is a polymer composition as defined in claim <NUM>. It was surprisingly discovered that polymer compositions including the LCP as defined in claim <NUM> in conjunction with a combination of flat glass fibers and boron nitride and zinc oxide had improved thermal conductivity and flexural properties, relative to analogous polymer compositions having round glass fibers in place of the flat glass fibers. As used herein, weight percent ("wt. %") is relative to the total weight of the polymer composition, unless explicitly stated otherwise.

Any description, even though described in relation to a specific embodiment, is applicable to and interchangeable with other embodiments of the present disclosure; where an element or component is said to be included in and/or selected from a list of recited elements or components, it should be understood that in related embodiments explicitly contemplated here, the element or component can also be any one of the individual recited elements or components, or can also be selected from a group consisting of any two or more of the explicitly listed elements or components; any element or component recited in a list of elements or components may be omitted from such list; and any recitation herein of numerical ranges by endpoints includes all numbers subsumed within the recited ranges as well as the endpoints of the range and equivalents.

The polymer compositions are defined in the claims. These polymer compositions surprisingly have improved thermal conductivity and flexural properties, relative to analogous polymer compositions having round glass fibers in place of the flat glass fibers. Additionally, in some embodiments, the polymer compositions have particularly desirable apparent viscosity for injection molding of thin-walled articles.

The polymer compositions have surprisingly improved thermal conductivity. As noted above, especially in high power density electrical component applications (e.g. electric motors for electric vehicles), there is a significantly increased thermal output, which results in heat accumulation in and around the electrical component. Therefore, there is a concomitant need to improve cooling. The polymer compositions described here have significantly improved thermal conductivity to help conduct heat away from electrical motor components. Of course, the same applies to any article (e.g. power supplies) that carries significant current or has large power density requirements. In some embodiments, the polymer composition has a through-plane thermal conductivity of at least <NUM> Watts per meter-Kelvin ("W/m-K"), at least <NUM> W/m-K, at least <NUM> W/m-K, at least <NUM> W/m-K, at least <NUM> W/m-K, at least <NUM> W/m-K, at least <NUM> W/m-K, at least <NUM> W/m-K or at least <NUM> W/m-K. In some embodiments, the polymer composition has a through-plane thermal conductivity of no more than <NUM> W/m-K or no more than <NUM> W/m-K. In some embodiments, the polymer composition has a through-plane thermal conductivity of from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K or from <NUM> W/m-K to <NUM> W/m-K. In some embodiments, the polymer composition has a through-plane thermal conductivity of from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K, from <NUM> W/m-K to <NUM> W/m-K or from <NUM> W/m-K to <NUM> W/m-K. Through-plane thermal conductivity can be measured as described in the Examples section.

The polymer compositions also exhibit enhanced flexural properties. In some embodiments, the polymer composition has a tensile strength at break ("tensile strength") of from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa or from <NUM> MPa to <NUM> MPa. In some embodiments, the polymer composition has a tensile strength of from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa or from <NUM> MPa to <NUM> MPa. In some embodiments, the polymer composition has a tensile strength of from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa or from <NUM> MPa to <NUM> MPa. In some embodiments, the polymer composition has a tensile strength of from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa, from <NUM> MPa to <NUM> MPa or from <NUM> MPa to <NUM> MPa. In some embodiments, the polymer composition has a tensile strain at break ("tensile strain") of from <NUM>% to <NUM>%, from <NUM>% to <NUM>% or from <NUM>% to <NUM>%. In some embodiments, the polymer composition has a tensile strain of from <NUM>% to <NUM>%, from <NUM>% to <NUM>% or from <NUM>% to <NUM>%. Tensile strength and tensile elongation can be measured as described in the Examples section.

In some embodiments, the polymer composition has an apparent viscosity ("η"), at a shear rate of <NUM> seconds-<NUM>, ("s-<NUM>") of from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa-s or from <NUM> Pa·s to <NUM> Pa·s. In some embodiments, the polymer compositions has an η, at a shear rate of <NUM>-<NUM>, of from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa·s or from <NUM> Pa·s to <NUM> Pa·s. In some embodiments, the polymer compositions has an η, at a shear rate of <NUM>-<NUM>, of from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa·s, or from <NUM> Pa·s to <NUM> Pa·s. In some embodiments, the polymer compositions has an η, at a shear rate of <NUM>-<NUM>, of from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa·s, from <NUM> Pa·s to <NUM> Pa·s or from <NUM> Pa·s to <NUM> Pa·s. η can be measured as described in the Examples section.

In some embodiments, the polymer composition has a melting temperature ("Tm") of at least <NUM>° C, at least <NUM>° C, or at least <NUM>° C. In some embodiments, the polymer composition has a Tm of no more than <NUM>° C, no more than <NUM>° C, or no more than <NUM>° C. In some embodiments, the polymer composition has a Tm of from <NUM>° C to <NUM>° C, from <NUM>° C to <NUM>° C, or from <NUM>° C to <NUM>° C. Tm can be measured according to ASTM D3418.

The LCP is formed from the polycondensation of the following monomers: terephthalic acid, an aromatic diol (<NUM>,<NUM>'-biphenol), an aromatic dicarboxylic acid distinct from terephthalic acid (isophthalic acid), and an aromatic hydroxycarboxylic acid (<NUM>-hydroxybenzoic acid).

The aromatic diol is <NUM>,<NUM>'-biphenol. The aromatic dicarboxylic acid distinct from terephthalic acid is isophthalic acid. The aromatic hydroxycarboxylic acid is <NUM>-hydroxybenzoic acid.

The LCP formed from the aforementioned monomers has recurring units RLCP1 to RLCP4. Recurring unit RLCP1 is represented by the following formula:
<CHM>.

Recurring unit RLCP2 is represented by formula (<NUM>):
<CHM>
Recurring unit RLCP3 is represented by formula (<NUM>):
<CHM>
Recurring unit RLCP4 is represented by formula (<NUM>):
<CHM>.

The person of ordinary skill in the art will recognize that RLCP1 according to formula (<NUM>) is formed from terephthalic acid; RLCP2 according to formula (<NUM>) is formed from isophthalic acid; RLCP3 according to formula (<NUM>) is formed from isophthalic acid; and RLCP4 according to formula (<NUM>) is formed from <NUM>-hydroxybenzoic acid.

In some embodiments, the total concentration of recurring units RLCP1 to RLCP4 is at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, at least <NUM> mol%, or at least <NUM> mol%. In some embodiments, the concentration of the terephthalic acid is from <NUM> mol% to <NUM> mol%, preferably from <NUM> mol% to <NUM> mol%. In some embodiments, the concentration of the aromatic diol is from <NUM> mol% to <NUM> mol%, preferably from <NUM> mol% to <NUM> mol%. In some embodiments, the concentration of the first aromatic dicarboxylic acid is from <NUM> mol% to <NUM> mol%, preferably from <NUM> mol% to <NUM> mol%. In some embodiments, the concentration of the aromatic hydrocarboxylic acid is from <NUM> mol% to <NUM> mol%, preferably from <NUM> mol% to <NUM> mol%, most preferably from <NUM> mol% to <NUM> mol%. As used herein, mol% of each recurring unit is relative to the total number of moles of recurring units in the polymer, unless explicitly indicated otherwise. For clarity, "derived from" refers the recurring unit formed from polycondensation of the recited monomer, for example, as described above with respect to the relationship between formulae <NUM> to <NUM> and <NUM> to <NUM>.

In some embodiments, the LCP has a Tm of at least <NUM>° C, at least <NUM>° C, or at least <NUM>° C. In some embodiments, the LCP has a Tm of no more than <NUM>° C, no more than <NUM>° C, or no more than <NUM>° C. In some embodiments, the LCP has a Tm of from <NUM>° C to <NUM>° C, from <NUM>° C to <NUM>° C, or from <NUM>° C to <NUM>° C.

In some embodiments, the LCP has a number average molecular weight ("Mn") of at least <NUM>,<NUM>/mol. In some embodiments, the LCP has an Mn of no more than <NUM>,<NUM>/mol. In some embodiments, the LCP has an Mn of from <NUM>,<NUM>/mol to <NUM>,<NUM>/mol. The number average molecular weight Mn can be determined by gel permeation chromatography (GPC) according to ASTM D5296 and using hexafluoroisopropanol solvent and poly(methyl methacrylate) standard.

The LCP concentration in the polymer composition is at least <NUM> wt %. In some embodiments, it is at least <NUM> wt. %, at least <NUM> wt. % or at least <NUM> wt. In some embodiments, the LCP concentration in the polymer composition is no more than <NUM> wt. %, no more than <NUM> wt. % or no more than <NUM> wt. In some embodiments, the LCP concentration in the polymer composition is from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt. In some embodiments, the LCP concentration in the polymer composition is from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt. In some embodiments, the LCP concentration in the polymer composition is from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt.

The LCP described herein can be prepared by any conventional method adapted to the synthesis of LCPs.

The polymer composition includes boron nitride and zinc oxide. As used herein and unless explicitly stated otherwise, "free of" a component means that the concentration of the component in the polymer composition is no more than <NUM> wt. %, no more than <NUM> wt. %, no more than <NUM> wt. % or no more than <NUM> wt.

The total concentration of boron nitride and zinc oxide in the polymer composition is from <NUM> wt. % to <NUM> wt. In some embodiments, the total concentration of boron nitride and zinc oxide is at least <NUM> wt. In some embodiments, the total concentration of boron nitride and zinc oxide is no more than <NUM> wt. %, no more than <NUM> wt. In some embodiments, the total concentration of boron nitride and zinc oxide is from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt. In some embodiments, the total concentration of boron nitride and zinc oxide is from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt. The relative concentration of the boron nitride to the zinc oxide (weight of boron nitride in the polymer composition / weight of zinc oxide in the polymer compositions) is from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM> or from <NUM> to <NUM>.

The polymer composition further includes a flat glass fiber. Glass fibers are silica-based glass compounds that contain several metal oxides which can be tailored to create different types of glass. The main oxide is silica in the form of silica sand; the other oxides such as calcium, sodium and aluminum are incorporated to reduce the melting temperature and impede crystallization. The glass fibers may be added as endless fibers or as chopped glass fibers. All glass fiber types, such as A, C, D, E, M, S, R, T glass fibers (as described in <NPL>), or any mixtures thereof or mixtures thereof may be used. For example, R, S and T glass fibers are high modulus glass fibers that have typically an elastic modulus of at least <NUM>, preferably at least <NUM>, more preferably at least <NUM>, and most preferably at least <NUM> GPa as measured according to ASTM D2343.

E, R, S and T glass fibers are well known in the art. They are notably described in <NPL>. R, S and T glass fibers are composed essentially of oxides of silicon, aluminium and magnesium. In particular, those glass fibers comprise typically from <NUM>-<NUM> wt. % of SiO<NUM>, from <NUM>-<NUM> wt. % of Al<NUM>O<NUM> and from <NUM>-<NUM> wt. % of MgO, based upon the total weight of the glass fibers. To the contrary of the regular E-glass fibers widely used in polymer compositions, R, S and T glass fibers comprise less than <NUM> wt. % of CaO, based upon the total weight of the glass composition.

Generally, the glass fiber has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness of at least <NUM>, at least <NUM>, at least <NUM> or at least <NUM>. In some embodiments, the glass fiber has an average length of from <NUM> to <NUM>. In some such embodiments, the glass fiber has an average length of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. In alternative embodiments, the glass fiber has an average length of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM> or from <NUM> to <NUM>. The average length of the glass fiber can be taken as the average length of the glass fiber prior to incorporation into the polymer composition or can be taken as the average length of the glass fiber in the polymer composition.

The flat glass fibers are glass fibers that have a non-circular cross-section, including oval, elliptical or rectangular.

In some embodiments, the glass fiber has a cross-sectional longest diameter of at least <NUM>, preferably at least <NUM>, more preferably at least <NUM>, still more preferably at least <NUM>. Additionally or alternatively, in some embodiments, the glass fiber has a cross-sectional longest diameter of at most <NUM>, preferably at most <NUM>, more preferably at most <NUM>, still more preferably at most <NUM>. In some embodiments, glass fiber has a cross-sectional longest diameter from <NUM> to <NUM>, preferably from <NUM> to <NUM> and more preferably from <NUM> to <NUM>. In some embodiments, the glass fiber has a cross-sectional shortest diameter of at least <NUM>, preferably at least <NUM>, more preferably at least <NUM>, still more preferably at least <NUM>. Additionally or alternatively, in some embodiments, the glass fiber has a cross-sectional shortest diameter of at most <NUM>, preferably at most <NUM>, more preferably at most <NUM>, still more preferably at most <NUM>. In some embodiments, the glass fiber has a cross-sectional shortest diameter of from <NUM> to <NUM>, preferably from <NUM> to <NUM> and more preferably from <NUM> to <NUM>. In some embodiments, the glass fiber has an aspect ratio of at least <NUM>, preferably at least <NUM>, more preferably at least <NUM>, still more preferably at least <NUM>. The aspect ratio is defined as a ratio of the longest diameter in the cross-section of the glass fiber to the shortest diameter thereof. In some embodiments, the glass fiber has an aspect ratio of at most <NUM>, preferably at most <NUM>, more preferably of at most <NUM>. In some embodiments, the glass fiber has an aspect ratio of from <NUM> to <NUM> or from <NUM> to <NUM>.

The shape of the cross-section of the glass fiber, its length, its cross-sectional diameter and its aspect ratio can be easily determined using optical microscopy. For example, the aspect ratio of the fiber cross-section may be determined using an Euromex optical microscope and an image analysis software (Image Focus <NUM>) by measuring the largest (width) and smallest (height) dimensions of the fiber cross-section and dividing the first number by the second number.

In some embodiments, the glass fibers have an elastic modulus of at least <NUM> GPa as measured according to ASTM C1557-<NUM>, of preferably at least <NUM>, more preferably at least <NUM>, even more preferably at least <NUM> and most preferably at least <NUM> GPa. In some embodiments, glass fibers have a tensile strength of at least <NUM> GPa as measured according to ASTM C1557-<NUM>, of preferably at least <NUM>, more preferably at least <NUM>, even more preferably at least <NUM> and most preferably at least <NUM> GPa. This level of elastic modulus and tensile strength is typically reached when using a specific chemical composition of the glass used to manufacture the glass fibers. Glass is a silica-based glass compound that contain several metal oxides which can be tailored to create different types of glasses. The main oxide is silica in the form of silica sand; the other oxides such as calcium, sodium and aluminum are incorporated to reduce the melting temperature and impede crystallization. It is well known in the art that when using a glass with a high loading of Al<NUM>O<NUM>, the glass fiber derived therefrom exhibit a high elastic modulus. In particular, those glass fibers comprise typically from <NUM>-<NUM> wt. % of SiO<NUM>, from <NUM>-<NUM> wt. % of Al<NUM>O<NUM> and from <NUM>-<NUM> wt. % of MgO, based on the total weight of the glass composition. To the contrary of the regular E-glass fibers widely used in polymer compositions, the high modulus glass fibers comprise less than <NUM> wt. % of B<NUM>O<NUM>, preferably less than <NUM> wt. %, based on the total weight of the glass composition.

The flat glass fiber concentration in the polymer composition is from <NUM> wt. % to <NUM> wt. In some embodiments, the flat glass fiber concentration in the polymer composition is from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. %, from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt. %, based on the total weight of the polymer composition.

In some embodiments, the polymer composition also includes an additive selected from the group consisting of additional reinforcing agents, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, nucleating agents and antioxidants.

A large selection of additional reinforcing agents can be added to the polymer composition. The additional reinforcing agent can be selected from fibrous and particulate reinforcing agents. A fibrous reinforcing agent is considered herein to be a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Generally, such a material has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness of at least <NUM>, at least <NUM>, at least <NUM> or at least <NUM>. In some embodiments, the fibrous reinforcing agents have an average length of from <NUM> to <NUM>. In some such embodiments, the fibrous reinforcing agents have an average length of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, or from <NUM> to <NUM>. In alternative embodiments, the fibrous reinforcing agents have an average length of from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM>, from <NUM> to <NUM> or from <NUM> to <NUM>. The average length of the fibrous reinforcing agents can be taken as the average length of the fibrous reinforcing agents prior to incorporation into the polymer composition or can be taken as the average length of the fibrous reinforcing agents in the polymer composition. Examples of fibrous reinforcing agents include, but not limited to, additional glass fibers (e.g. round glass fibers), carbon fibers, synthetic polymeric fibers, aramid fibers, aluminum fibers, titanium fibers, magnesium fibers, boron carbide fibers, rock wool fibers, and steel fibers. Round glass fibers are glass fibers having a substantially circular cross section (e.g. a cross section having perpendicular axes within the cross sectional plane that differ in length by no more than <NUM>%, no more than <NUM>%, or no more than <NUM>%) Particulate reinforcing agents include, but not limited to, talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate and wollastonite).

In some embodiments, the reinforcing agent concentration in the polymer composition is at least <NUM> wt. %, at least <NUM> wt. %, at least <NUM> wt. % or at least <NUM> wt. In some embodiments, the reinforcing agent concentration is no more than <NUM> wt. In some embodiments, the reinforcing agent concentration is from <NUM> wt. % to <NUM> wt. % or from <NUM> wt. % to <NUM> wt.

In some embodiments, the polymer composition is free of a reinforcing agent. In some embodiments, the polymer composition is free of additional glass fibers. In some embodiments, the polymer composition is free of round glass fibers. With respect to reinforcing agents (e.g. additional glass fibers or round glass fibers) free of means the concentration of the reinforcing agent is less than <NUM> wt. %, less than <NUM> wt. %, less than <NUM> wt. % or less than <NUM> wt.

The polymer composition may also comprise a toughener. A toughener is generally a low glass transition temperature (Tg) polymer, with a Tg for example below room temperature, below <NUM> or even below -<NUM>. As a result of its low Tg, the toughener are typically elastomeric at room temperature. Tougheners can be functionalized polymer backbones.

The polymer backbone of the toughener can be selected from elastomeric backbones comprising polyethylenes and copolymers thereof, e.g. ethylene-butene; ethylene-octene; polypropylenes and copolymers thereof; polybutenes; polyisoprenes; ethylene-propylene-rubbers (EPR); ethylene-propylene-diene monomer rubbers (EPDM); ethylene-acrylate rubbers; butadiene-acrylonitrile rubbers, ethylene-acrylic acid (EAA), ethylene-vinylacetate (EVA); acrylonitrile-butadiene-styrene rubbers (ABS), block copolymers styrene ethylene butadiene styrene (SEBS); block copolymers styrene butadiene styrene (SBS); core-shell elastomers of methacrylate-butadiene-styrene (MBS) type, or mixture of one or more of the above.

When the toughener is functionalized, the functionalization of the backbone can result from the copolymerization of monomers which include the functionalization or from the grafting of the polymer backbone with a further component.

Specific examples of functionalized tougheners are notably terpolymers of ethylene, acrylic ester and glycidyl methacrylate, copolymers of ethylene and butyl ester acrylate; copolymers of ethylene, butyl ester acrylate and glycidyl methacrylate; ethylene-maleic anhydride copolymers; EPR grafted with maleic anhydride; styrene copolymers grafted with maleic anhydride; SEBS copolymers grafted with maleic anhydride; styrene-acrylonitrile copolymers grafted with maleic anhydride; ABS copolymers grafted with maleic anhydride.

In some embodiments, the toughener concentration is at least <NUM> wt. %, at least <NUM> wt. % or at least <NUM> wt. Additionally or alternatively, in some embodiments the toughener concentration is no more than <NUM> wt. %, no more than <NUM> wt. %, no more than <NUM> wt. % or no more than <NUM> wt.

The polymer composition may also include other conventional additives commonly used in the art, including plasticizers, colorants, pigments (e.g. black pigments such as carbon black and nigrosine), antistatic agents, dyes, lubricants (e.g. linear low density polyethylene, calcium or magnesium stearate or sodium montanate), thermal stabilizers, light stabilizers, nucleating agents and antioxidants.

The polymer compositions can be prepared by melt-blending the LCP and the specific components (e.g. the flat glass fiber and the boron nitride and zinc oxide), and of any other additives.

Any suitable melt-blending method known in the art may be used for mixing polymeric ingredients and non-polymeric ingredients. For example, polymeric ingredients and non-polymeric ingredients may be fed into a melt mixer, such as single screw extruder or twin screw extruder, agitator, single screw or twin screw kneader, or Banbury mixer, and the addition step may be addition of all ingredients at once or gradual addition in batches. When the polymeric ingredient and non-polymeric ingredient are gradually added in batches, a part of the polymeric ingredients and/or non-polymeric ingredients is first added, and then is melt-mixed with the remaining polymeric ingredients and non-polymeric ingredients that are subsequently added, until an adequately mixed composition is obtained. If a reinforcing agent presents a long physical shape (for example, a long glass fiber), drawing extrusion molding may be used to prepare a reinforced composition.

The polymer compositions can be desirably incorporated into articles. The article can notably be used in application settings where thin-walled articles are molded (e.g. injection molded) from the polymer composition.

As used herein a thin-walled article is an article that has a portion with a maximum thickness (along a line perpendicular to the surface at which the measurement is taken) of no more than <NUM>, no more than <NUM>, no more than <NUM> or no more than <NUM>. Preferably, the portion is a region on the surface of the article having an area of at least <NUM><NUM>, at least <NUM><NUM>, at least <NUM><NUM>, or at least <NUM><NUM>.

In some embodiments, the article is an automotive component, an aerospace component or a watercraft component (including but not limited to boats and jet skis). In some embodiments, including but not limited to the aforementioned embodiments, the articles is an electrical component (e.g. an electrical automotive component). In some embodiments, the electrical component is in contact with, or includes, a current carrier. In some embodiments, including but not limited to the aforementioned embodiments, the article is an electric motor component (e.g. an electrical automotive motor component). In some embodiments, the article is a slot liner. Slot liners are incorporated into the stators or rotors of electric motors (including generators). Slot liners provide insulation between the stator core or motor core and, respectively, the stator windings or rotor winding. As mentioned above, the polymer compositions described herein are particularly desirable for high power density motor applications at least because of the significantly improved through-plane thermal conductivity. For clarity, the articles described above can be thin-walled articles or non-thin-walled articles. Preferably the articles are thin-walled articles.

Melt extrusion involves forcing molten polymer or polymer composition through a die or orifice. The molten polymer can be formed during melt-blending, as described above, or it can be formed by melting pre-formed polymer or polymer composition, for example, in the form of pellets. For injection molding applications, the molten polymer is forced into a mold, where it solidifies prior to being ejected (removed from the mold). In some embodiments where molten polymer is formed by melt-blending (e.g. extrusion), the mold can be directly or indirectly coupled to the melt-blending apparatus (e.g. extruder) such that the polymer composition is forced into the mold before significantly cooling. In other embodiments, solid pellets of polymer or polymer composition can be melted and the melting apparatus can be directly or indirectly coupled to the mold so that molten polymer or polymer composition can be fed into the mold. The mold corresponds to the shape of the article to be formed. As noted above, the polymer compositions have extremely desirable melt viscosities for injection molding applications, particularly with respect to thin-walled articles formed by injection molding.

The article can be printed from the polymer composition, by a process comprising a step of extrusion of the material, which is for example in the form of a filament, or comprising a step of laser sintering of the material, which is in this case in the form of a powder.

A method for manufacturing a three-dimensional (3D) object with an additive manufacturing system is also provided, comprising: providing a part material comprising the polymer composition, and printing layers of the three-dimensional object from the part material.

The polymer composition can therefore be in the form of a thread or a filament to be used in a process of 3D printing, e.g. Fused Filament Fabrication, also known as Fused Deposition Modelling (FDM).

The polymer composition can also be in the form of a powder, for example a substantially spherical powder, to be used in a process of 3D printing, e.g. Selective Laser Sintering (SLS).

The following examples demonstrate the film forming capabilities and the dielectric and mechanical performance of the polymer compositions. The following materials were used in the examples:.

To synthesize the LCP, the dicarboxylic acid monomers (terephthalic acid (<NUM>, Flint Hills Resources), isophthalic acid (<NUM>, Lotte Chemicals), p-hydroxybenzoic acid (<NUM>, Sanfu), <NUM>,<NUM>'-biphenol (<NUM>, SI Group) and acetic anhydride (<NUM>, Aldrich)) were charged into a <NUM>-L glass reactor. Potassium acetate (<NUM>, Aldrich) and magnesium acetate (<NUM>, Aldrich) were used as catalysts. The mixture was heated to <NUM> and the acetylation reaction under reflux condition was allowed to proceed for 1hr. The heating then continued to <NUM> at the rate of <NUM> per minute while distilling off acetic acid from the reactor. The pre-polymer was discharged and allowed to cool down. The material was then ground into powder for solid-state polymerization. The resin was advanced in a rotatory oven using the following profile: 1hr at <NUM>, 1hr at <NUM> and <NUM> hrs at <NUM> under continuous nitrogen purging. The resulting high molecular resin had melt viscosity between <NUM>-<NUM> Pa-s at <NUM>.

Samples were formed by melt blending the polymer compositions in an extruder and cut into pellets. Samples for thermal testing and mechanical testing were formed by injection molding. Sample parameters are displayed in Table <NUM>. All values in Table <NUM> are in wt. %, and are based upon the total weight of the polymer composition.

This Example demonstrates the thermal, mechanical and rheological performance of the samples.

To demonstrate thermal performance, through plane conductivity was measured by the flash method using a Netzsch LFA <NUM> HyperFlash instrument and according to ASTM E1461-<NUM>, "Standard Test Method for Thermal Diffusivity by the Flash Method". To demonstrate mechanical performance, flexural strength and flexural strain were measured according to ASTM D790. To demonstrate rheological performance, η (apparent viscosity) was measured according to ASTM D3835. The results of thermal, mechanical and rheological performance are displayed in Table <NUM>.

The samples having a combination of flat glass fiber and boron nitride had improved through-plane conductivity, flexural strength at break, and flexural strain at break, relative to samples having a combination of round glass fiber and boron nitride. Referring to Table <NUM>, comparison of C1 and E4 demonstrates that the addition of boron nitride to a flat glass fiber filed LCP composition (E4) results in a through plane conductivity of <NUM> W/m-K, representing about a <NUM>% improvement relative to an analogous LCP composition free of boron nitride (C1). Comparison of C2 and C3 demonstrates that addition of boron nitride to a round glass fiber filled LCP composition (C3) results in a through plane conductivity of only about <NUM> W/m-K, which is less than that for E4 and which represents only about a <NUM>% improvement relative to an analogous LCP composition free of boron nitride (C2). Still further, while the addition of boron nitride in E4, relative to C1, and C3, relative to C2, decreases the flexural strength at break and flexural strain at break, E4 has improved flexural strength at break and flexural strain at break, relative to C3.

Similarly, the samples having a combination of flat glass fiber and zinc oxide had improved through-plane conductivity, flexural strength at break, and flexural strain at break, relative to samples having a combination of round glass fiber and zinc oxide. Referring to Table <NUM>, comparison of C1 and E5 demonstrates that the addition of zinc oxide to a flat glass fiber filed LCP composition (E5) results in a through plane conductivity of <NUM> W/m-K, representing about a <NUM>% improvement relative to an analogous LCP composition free of zinc oxide (C1). Comparison of C2 and C4 demonstrates that addition of zinc oxide to a round glass fiber filled LCP composition (C4) results in a through plane conductivity of only about <NUM> W/m-K, which is slightly less than that for E4 and which represents about a <NUM>% reduction relative to an analogous LCP composition free of zinc oxide (C2). Still further, while the addition of zinc oxide in E5, relative to C1, and C4, relative to C2, decreases the flexural strength at break and flexural strain at break, E5 has improved flexural strength at break and flexural strain at break, relative to C4.

Claim 1:
A polymer composition consisting of:
- at least <NUM> wt.% of a liquid crystal polymer ("LCP") formed from the polycondensation of the following monomers: terephthalic acid; <NUM>,<NUM>'-biphenol; isophthalic acid; and <NUM>-hydroxybenzoic acid;
- from <NUM> wt.% to <NUM> wt.% of a flat glass fiber; and
- boron nitride and zinc oxide, wherein the total concentration of boron nitride and zinc oxide is from <NUM> wt.% to <NUM> wt.%.;
- optionally an additive selected from the group consisting of tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, thermal stabilizers, light stabilizers, nucleating agents and antioxidants;
- wherein the relative concentration of boron nitride to zinc oxide expressed as weight of boron nitride in the polymer composition / weight of zinc oxide in the polymer composition is from <NUM> to <NUM>.