JP2013127067A - Heat-resistant and light-resistant polymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-resistant and light-resistant polymer composition.SOLUTION: The invention relates to: a polymer composition; and articles such as LED devices comprising at least one polyester, at least one hindered amine compound, and at least one phosphorus compound selected from phosphonite esters, phosphonites and mixtures thereof.

Description

  The present invention relates to a polymer composition comprising at least one polyester, at least one hindered amine compound, and at least one phosphorus compound selected from the group consisting of phosphite esters, phosphonites and mixtures thereof.

  The present invention further provides articles, such as components of light emitting diode (LED) devices, comprising the composition of the present invention.

  LEDs are increasingly being used as light sources in many applications because they have many advantages over conventional light sources. LEDs generally consume significantly less power than incandescent and other light sources, require lower operating voltages, and are mechanical shock resistant. As a result, they are replacing incandescent and other light sources in many applications and are applied in different fields such as traffic signals, indoor and outdoor lighting, mobile phone displays, automotive displays and flashlights. Yes.

  LED components, such as housings, reflectors and reflectors, require a particularly demanding combination of very good color and improved physical properties. Although ceramics may advantageously be used in these applications, they are still very expensive and require demanding processing techniques. Therefore, polymer compositions have been extensively studied and developed to replace ceramic as a lower cost material. The great advantage of polymers is that they may be injection molded and thus can provide considerable design flexibility. LED applications require polymer compositions that have sufficient opacity and good reflective properties. One problem that has been pointed out with respect to polymer compositions used for the manufacture of LED components is that they tend to yellow when exposed to light and high temperatures. For example, during manufacture, the LED component is heated to about 180 ° C. to cure the epoxy or silicon encapsulant. Also, LED components are exposed to temperatures above 260 ° C. during the soldering operation. In addition, while in use, LED components such as automobile parts are routinely exposed to temperatures in excess of 80 ° C. This high temperature exposure causes yellowing of the polymer composition used to form the LED component.

  Desirably, LED reflectors and ultimately the polymer compositions from which they are made have high reflectivity of light (typically visible light), high whiteness, good processability (eg, good moldability). Suitability), high dimensional stability (significantly low linear expansion), high mechanical strength, high heat deflection temperature, and high heat resistance (low discoloration and low reflectivity when exposed to high temperatures) It is better to satisfy a series of requirements.

  Unfortunately, various prior art polymer compositions used in LED applications tend to yellow when exposed to light and heat.

  U.S. Patent No. 6,099,077 discloses a light emitting diode assembly housing comprising a poly (1,4-cyclohexanedimethanol terephthalate) (PCT) composition. More specifically, (Patent Document 1) includes PCT 40 to 95% by weight, titanium dioxide 5 to 60% by weight, at least one inorganic reinforcing agent or filler 0 to 40% by weight, and at least one oxidation stabilizer 0. For light emitting diode assembly housing compositions comprising ˜3 wt%, the weight percentage is based on the total weight of the composition.

  Those skilled in the art recognize that further improvements in thermal stability, molding performance and reflectivity are advantageous for the development of LED devices.

  The inventors have discovered that the presence of two specific additives synergistically greatly enhances the properties of the polyester composition when exposed to heat and light simultaneously.

  The polyester composition according to the present invention meets the above-mentioned requirements and is described in detail below.

International Publication No. 2007/033129 Pamphlet

Plastics Additives Handbook, 5th edition, Hanser, 2001 Additives for Plastics Handbook, 2nd edition, chapter 5.2.3 by John Murphy, pages 43-48

In a first aspect, the present invention provides:
-At least one polyester;
-At least one hindered amine compound;
-Relates to a polymer composition comprising at least one phosphorus compound selected from the group consisting of phosphite esters, phosphonites and mixtures thereof.

  In a second aspect, the present invention relates to an article comprising at least one component comprising the polymer composition of the present invention, in particular to a component of an LED device made from such a composition.

The polymer composition according to the present invention comprises three essential components which are described in detail below.
Polyester The term “polyester” refers to a polymer comprising at least 50 mol%, preferably at least 85 mol%, of repeating units comprising at least one ester moiety (generally described by the formula R— (C═O) —OR). Intended to mean. Polyesters can be produced by ring-opening polymerization of cyclic monomers (M _A ) containing at least one ester moiety, by polycondensation of monomers (M _B ) containing at least one hydroxyl group and at least one carboxylic acid group, or at least two Obtained by polycondensation of at least one monomer (M _C ) (diol) containing a hydroxyl group and at least one monomer (M _D ) (dicarboxylic acid) containing at least two carboxylic acid groups.

Non-limiting examples of monomers (M _A ) include lactide and caprolactone.

Non-limiting examples of monomers (M _B ) include glycolic acid, 4-hydroxybenzoic acid, 6-hydroxynaphthalene-2-carboxylic acid and the like.

Non-limiting examples of monomers (M _C ) include 1,4-cyclohexanedimethanol, ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6- Although there are hexanediol and neopentyl glycol, 1,4-cyclohexanedimethanol and neopentyl glycol are preferred.

Non-limiting examples of monomers (M _D ) include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, cyclohexanedicarboxylic acid, succinic acid, sebacic acid, and adipic acid, with terephthalic acid and cyclohexanedicarboxylic acid being preferred. .

  Depending on the choice of monomer, the polyester can be either fully aliphatic, semi-aromatic, or fully aromatic.

  The polyester of the composition of the present invention may be a copolymer or a homopolymer.

  When the polyester of the composition of the present invention is a copolymer, preferably at least 50 mol%, more preferably at least 60 mol%, even more preferably at least 70 mol%, even more preferably at least 80 mol% of repeating units, and Most preferably at least 90 mol% is obtained by polycondensation of terephthalic acid. More preferably, at least 50 mol%, even more preferably at least 60 mol%, even more preferably at least 70 mol%, and most preferably at least 80 mol% of the repeating units are terephthalic acid and 1,4-cyclohexylene di- Obtained by polycondensation with methanol.

  When the polyester of the composition of the present invention is a homopolymer, it may be polyglycolide or polyglycolic acid (PGA), polylactic acid (PLA), polycaprolactone (PCL), polyethylene adipate (PEA), polyhydroxyalkanoate (PHA). ), Polybutylene terephthalate (PBT), polypropylene terephthalate (PPT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), poly (1,4-cyclohexylenedimethylene terephthalate) (PCT) ), And liquid crystal polyester (LCP). It is preferably selected from the group consisting of PBT, PTT, PEN, PET, PCT and LCP. More preferably it is selected from the group consisting of PBT, PCT and LCP. Most preferably it is PCT (ie a homopolymer obtained by polycondensation of terephthalic acid and 1,4-cyclohexylenedimethanol).

  The polymer composition according to the invention may also comprise at least two polyesters. In such cases, the polyester is preferably selected from a blend of PCT and LCP or PBT and PCT.

  The polyester used herein advantageously has an intrinsic viscosity number of about 0.6 to about 2.0 dl / g when measured at about 30 ° C. in a 60:40 phenol / tetrachloroethane mixture or similar solvent. Have. Particularly suitable polyesters for the present invention have an intrinsic viscosity number of 0.6 to 1.4 dl / g.

  The polyester used here advantageously has a melting point of at least 250 ° C., preferably at least 260 ° C., more preferably at least 270 ° C. and most preferably at least 280 ° C. as measured by DSC according to ISO-11357-3. Have. Furthermore, their melting points are at most 350 ° C., preferably at most 340 ° C., more preferably at most 330 ° C. and most preferably at most 320 ° C.

  Polyesters particularly suitable for the present invention have a melting point in the range of 280 ° C to 320 ° C.

  The polyester is preferably present in an amount of at least 48 wt%, more preferably at least 50 wt%, even more preferably at least 52 wt%, and most preferably at least 54 wt%, based on the total weight of the composition.

  Also, the polyester is advantageously at most 90%, preferably at most 85%, more preferably at most 80%, even more preferably at most 75%, based on the total weight of the composition. It is present in an amount of wt%, and most preferably at most 70 wt%.

  Very good results have been obtained when the polyester is present in the composition in an amount of from about 48 to about 90% by weight, preferably from about 50 to about 70% by weight, based on the total weight of the composition.

Hindered amine compound The polymer composition according to the invention comprises at least one hindered amine compound in addition to the polyester.

  The term “hindered amine compound” is intended to mean a derivative of 2,2,6,6-tetramethylpiperidine known in the art (see, for example, (Non-patent Document 1)). The hindered amine compound of the composition according to the present invention may be either low molecular weight or high molecular weight.

  Low molecular weight hindered amine compounds typically have a molecular weight of at most 900, preferably at most 800, more preferably at most 700, even more preferably at most 600 and most preferably at most 500 g / mol. Have

  Examples of low molecular weight hindered amine compounds are listed in Table 1 below.

  Among these low molecular weight compounds, the hindered amine is preferably selected from the group consisting of hindered amines corresponding to formulas (a1), (a2), (a11) and (a12). More preferably, the hindered amine is selected from the group consisting of hindered amines corresponding to formulas (a1), (a2), and (a12). Even more preferably, the hindered amine is a hindered amine corresponding to formula (a2).

  The high molecular weight hindered amine compound is typically a polymer and typically has a molecular weight of at least 1000, preferably at least 1100, more preferably at least 1200, even more preferably at least 1300 and most preferably at least 1400 g / mol.

  Examples of high molecular weight hindered amine compounds are listed in Table 2 below.

  “N” in the formulas (b1) to (b6) in Table 2 represents the number of repeating units in the polymer, and is usually an integer of 4 or more.

  Among these high molecular weight compounds, the hindered amine is preferably selected from the group consisting of hindered amines corresponding to formulas (b2) and (b5). More preferably, the hindered amine is a hindered amine corresponding to formula (b2).

  The hindered amine compound is typically advantageously at least 0.05%, more preferably at least 0.1%, even more preferably at least 0.15%, and most preferably based on the total weight of the composition. Present in an amount of at least 0.2% by weight.

  Also, the hindered amine compound is typically advantageously at most 3.5 wt%, preferably at most 3 wt%, more preferably at most 2.5 wt%, based on the total weight of the composition, Even more preferably it is present in an amount of at most 2.0% by weight, even more preferably at most 0.8% by weight and most preferably at most 0.6% by weight.

  The hindered amine compound is present in the composition in an amount of from about 0.05 to about 2%, preferably from about 0.1 to about 0.8%, more preferably from about 0.2 to about 0. 0%, based on the total weight of the composition. Very good results were obtained when present in an amount of 6% by weight.

Phosphorus Compound The polymer composition according to the present invention comprises, in addition to the polyester and at least one hindered amine compound, at least one phosphorus compound selected from the group consisting of phosphite esters, phosphonites and mixtures thereof.

The phosphite ester may be represented by the formula P (OR) ₃ and the phosphonite may be represented by the formula P (OR) ₂ R, wherein each of R may be the same or different, typically And independently selected from the group consisting of C _1-20 alkyl, C _3-22 alkenyl, C _6-40 cycloalkyl, C _7-40 cycloalkylene, aryl, alkaryl, or arylalkyl moieties.

  The phosphorus compounds present in the composition according to the invention are known in the art and are described in detail, for example, in (Non-Patent Document 1).

  Examples of phosphite esters are listed in Table 3 below.

Among these phosphite esters, the phosphorus compound is preferably selected from the group consisting of phosphorus compounds corresponding to formulas (α5), (α9) and (α12). More preferably, the phosphorus compound is selected from the group consisting of phosphorus compounds corresponding to formulas (α5) and (α9). Even more preferably, the phosphite ester is a phosphite ester corresponding to formula (α5).
Examples of phosphonites are listed in Table 4 below.

  Preferably, the phosphonite is a phosphonite corresponding to formula (β1).

  The phosphorus compound is preferably a phosphite ester, and most preferably a phosphite ester corresponding to the above formula (α5).

  The phosphorus compound is preferably at least 0.3 wt%, more preferably at least 0.5 wt%, even more preferably at least 0.7 wt%, and most preferably at least 0.8 wt%, based on the total weight of the composition. Present in an amount of% by weight.

  Also, the phosphorus compound is preferably at most 5% by weight, more preferably at most 3% by weight, even more preferably at most 2.5% by weight, even more preferably based on the total weight of the composition. It is present in an amount of at most 2% by weight and most preferably at most 1.8% by weight.

  The phosphorus compound is about 0.3 to about 5%, preferably about 0.5 to about 2%, more preferably about 0.7 to about 1.8% by weight in the composition, based on the total weight of the composition. Very good results were obtained when present in an amount of%.

Optional Ingredients The composition of the present invention may contain other ingredients in addition to the three described above. In particular, the polymer composition may further comprise at least one reinforcing filler.

  Reinforcing fillers are known to those skilled in the art and may be added to the composition according to the invention. They are preferably selected from fiber fillers and particulate fillers. More preferably, the reinforcing filler is an inorganic filler (eg, talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate), glass fiber, carbon fiber, synthetic polymer fiber, aramid fiber, aluminum fiber, titanium fiber, magnesium. Selected from fiber, boron carbide fiber, rock wool fiber, steel fiber, wollastonite and the like. Even more preferably, it is selected from talc, mica, kaolin, calcium silicate, magnesium carbonate, glass fiber, carbon fiber and wollastonite. Even more preferably, the reinforcing filler is selected from glass fibers, wollastonite, carbon fibers, talc, mica and kaolin.

Fiber fillers particular class consists of a variety of sources, for example, _{Al 2 O 3, SiC, BC} , whiskers made of Fe and Ni, i.e. single-crystal fibers. Of the fiber fillers, glass fibers are preferred. They include chopped strands A-, E-, C-, D-, S- and R-glass fibers, as described in (Non-patent Document 2). Preferably, the filler is selected from fiber fillers.

  In a preferred embodiment of the invention, the reinforcing filler is selected from wollastonite and glass fiber. Very good results have been obtained when wollastonite and / or glass fiber are used. The glass fibers may have a round cross section or an elliptical cross section (also called flat fibers).

  When present, the reinforcing filler is preferably at least 2%, more preferably at least 4%, even more preferably at least 5%, and most preferably, based on the total weight of the composition according to the invention. Present in an amount of at least 10% by weight. When present, the reinforcing filler is also preferably at most 40% by weight, more preferably at most 30% by weight, even more preferably at most 25, based on the total weight of the composition according to the invention. It is present in an amount of wt%, and most preferably at most 20 wt%.

  When the reinforcing filler is present in the composition in an amount of from about 5 to about 40%, preferably from about 5 to about 25%, more preferably from about 10 to about 20% by weight, based on the total weight of the composition. Very good results were obtained.

  The polymer composition according to the invention may also comprise at least one white pigment different from the reinforcing filler defined above.

The white pigment is preferably selected from the group consisting of TiO ₂ , ZnS ₂ , ZnO, and BaSO ₄ .

  The white pigment is advantageously in the form of particles, preferably having a weight average particle size (equivalent diameter) of less than 5 μm. Larger particle sizes can adversely affect the properties of the composition. Preferably, the weight average particle size of the particles is less than 1 μm. Furthermore, it is preferably greater than 0.1 μm.

  The shape of the particles is not particularly limited. They may in particular be round, flaky, flat and so on.

The white pigment is preferably titanium dioxide (TiO ₂ ). The form of titanium dioxide is not particularly limited, and various crystal forms such as anatase form, rutile form, and monoclinic type can be used. However, the rutile form is preferred because of its higher refractive index and its very good light stability. Titanium dioxide may or may not be treated with a surface treatment agent. Preferably, the average particle diameter of titanium oxide is in the range of 0.15 μm to 0.35 μm.

  The surface of the titanium dioxide particles is preferably coated. The titanium dioxide is preferably first coated with an inorganic paint and then with an organic paint, which is applied over the inorganic paint. The titanium dioxide particles may be coated using any method known in the art. A preferred inorganic coating contains a metal oxide. The organic paint may contain one or more of carboxylic acids, polyols, alkanolamines, and / or silicon compounds.

  When present, the white pigment is preferably at least 1%, preferably at least 6%, more preferably at least 8%, even more preferably at least 10% by weight, based on the total weight of the composition, and Most preferably it is present in an amount of at least 15% by weight. Furthermore, when present, the white pigment is also preferably at most 50% by weight, preferably at most 40% by weight, more preferably at most 35% by weight, based on the total weight of the composition, Even more preferably it is present in an amount of at most 30% by weight and most preferably at most 25% by weight.

  Very good results have been obtained when titanium dioxide is used in an amount of 10-30% by weight, preferably 15-25% by weight, based on the total weight of the composition.

  The composition may also optionally contain up to about 15% by weight of one or more polymer toughening agents. The toughener is typically an elastomer having a relatively low melting point, generally less than 200 ° C., preferably less than 150 ° C., with functional groups capable of reacting with the polyester (and optionally other polymers present). Combined with it. Since polyesters typically have carboxyl and hydroxyl groups present, the toughener is generally selected from those containing functional groups that can react with carboxyl and / or hydroxyl groups. Examples of such functional groups include epoxy, carboxylic acid anhydride, hydroxyl (alcohol), carboxyl, and isocyanate. Preferred functional groups are epoxies and carboxylic anhydrides, with epoxies being particularly preferred. Such functional groups are usually copolymerized with monomers containing the desired functional groups by grafting small molecules onto already existing polymers or when the polymer toughener molecules are produced by copolymerization. Is “bound” to the polymer toughener. As an example of grafting, maleic anhydride may be grafted onto a hydrocarbon rubber using free radical grafting techniques. The resulting grafted polymer has carboxylic anhydride and / or carboxyl groups attached to it.

  Also, the composition according to the present invention may optionally contain up to about 5% of at least one nucleating agent. Non-limiting examples of nucleating agents include sodium benzoate and structures derived therefrom, linear alcohols with 30-50 carbon atoms, talc, boron nitride, and LCP.

  The composition may optionally further contain up to about 3% by weight of a UV stabilizer or UV blocker. Examples include triazole and triazine, oxanilide, hydroxybenzophenone, benzoate, and α-cyanoacrylate. When present, the UV stabilizer is preferably about 0.1 to about 3%, or preferably about 0.1 to about 1%, or more preferably about 0.1% by weight of the total weight of the composition. Present in an amount of about 0.6% by weight. The composition according to the invention is a melt-mixed blend in which all of the polymer components are well dispersed in each other and all of the non-polymer components are well dispersed in and bound by the polymer matrix, As a result, the blend is formed as a whole.

  The composition according to the invention may also comprise other polymers than the above-mentioned polyesters such as, for example, polycarbonate, polyethylene glycol, polysulfone, PEEK and polyphthalamide.

  The composition according to the invention may also contain other optional ingredients such as mold release agents, plasticizers, lubricants and other stabilizers different from those mentioned above.

  Any melt mixing method may be used to combine the polymeric and non-polymeric components of the present invention. For example, the polymer component and the non-polymer component are added all at the same time or stepwise to a melt mixer such as, for example, a single or twin screw extruder, blender, kneader, or Banbury mixer, by a single step addition, and then It may be melt mixed. When the polymer component and non-polymer component are added stepwise, a portion of the polymer component and / or non-polymer component is first added and melt mixed, and the remaining polymer component and non-polymer component are then added Further melt mixing until a mixed composition is obtained.

  Another aspect of the invention relates to an article comprising the above-described polymer composition, in particular, a component of an LED device.

  As used herein, the terms “light emitting diode device” and “LED device” refer to a device that includes at least one light emitting diode, an electrical connection that can connect the diode to an electrical circuit, and a diode in part. It is intended to mean an enclosing enclosure. The LED device may optionally have a lens that completely or partially covers the LED.

  Articles made from the composition according to the present invention may be formed from the composition of the present invention by any suitable melt processing method known to those skilled in the art, such as injection molding.

  The articles of the present invention are preferably LED device components such as housings, reflectors and reflectors.

  The article may be overmolded onto a metal (eg copper coated with copper or silver) leadframe that can be used to make an electrical connection to the encased LED. The article preferably has a cavity in a portion of the enclosure surrounding the LED, which serves to reflect the LED light in the outward direction and, if present, in the direction of the lens. The cavity may be cylindrical, conical, parabolic, or other curved form, and preferably has a smooth surface. Alternatively, the cavity walls may be parallel or substantially parallel to the diode. The lens may be formed over the diode cavity and may comprise an epoxy or silicone material.

  Articles of the invention include, for example, traffic signals, large area displays (such as video displays), video screens, indoor and outdoor lighting, mobile phone display backlights, automotive displays, car brake lights, car headlamps, It may be incorporated into LED devices used in applications such as laptop computer display backlights, pedestrian floor lighting, and flashlights.

  Although the present disclosure is now described with working examples, it is intended to illustrate the invention and is not intended to imply any limitation on the scope of the disclosure.

The following commercially available materials were used.
Polyester: PCT polyester glass fiber manufactured by Eastman ™ Chemical Products:
Glass fiber-1: OCV995 manufactured by OCV (trademark) Reinforcements
Glass fiber-2: OCV952A manufactured by OCV (trademark) Reinforcements
-Glass fiber-3: T-127H manufactured by NEG (Nippon Electric Glass)

titanium dioxide:
-TiO ₂ -1: DuPont Titanium Technologies Ltd. of Ti-Pure (R) R-350- manufactured by the chloride process rutile _TiO 2 treated with silica and alumina.
-TiO ₂ -2: Ishihara Sangyo Tipaque Co., Ltd. (registered trademark) manufactured by PC-3- chloride process rutile _TiO 2 treated with silica and alumina.

Stabilizers and additives:
Phosphorus compound 1 (PC-1): ULTRANOX® 626 is a phosphite ester stabilizer— (2,4-di-t-butylphenyl) pentaerythritol of the formula (α5) detailed above Diphosphite, manufactured by Chemtura.
Phosphorus compound 2 (PC-2): IRGAFOS® P-EPQ is a phosphonite stabilizer—tetrakis (2,4-di-tert-butylphenyl) of the formula (β1) described in detail above [ 1,1-biphenyl] -4,4′diylbisphosphonite, manufactured by Ciba.
Hindered amine: NYLOSTAB® S-EED stabilizer is a hindered amine corresponding to formula (a2) and is described in Clariant Corp. It is made.
-Talc: Imi Fabi L. L. C. Imi-Fabi ™ HTP-4 manufactured by
-LLDPE: linear low density polyethylene GRSN-9820NT7 made by DOW.

General Procedure for Preparation of Composition The polyester resin described above was fed to the first barrel of a ZSK26 twin screw extruder containing 12 zones by a loss-in metered feeder. The barrel set temperature was in the range of 240-300 ° C. and the resin was melted in front of zone 5. The other ingredients were fed into area 5 through a side ram extruder by a loss-in metered feeder. The screw speed was 175 rpm. The extrudate was cooled and pelletized using conventional equipment.

  The properties and amounts of the various components used are summarized in Table 5 and the amount of each component is given in weight percent.

Reflectance measurements The properties of parts made from the composition of the present invention in LED devices were simulated by exposing the sample to light at 180 ° C. for 12 days. Therefore, a disk having a diameter of about 50 mm and a thickness of about 1.6 mm was prepared using each of the compositions of Example E4 and Comparative Examples CE1-CE3.

  The discs were placed in a 180 ° C. oven equipped with a luminaire including a lamp 400 W UV F / 2 and an Optivex ™ UV filter for 12 days. The reflectance was measured with a BKY-Gardner spectrophotometer. The reflectivity results of the as-cast disk and the disk after exposure to light and high heat (180 ° C.) for 12 days, and the percentage retention of reflectivity at a wavelength of 460 nm are listed in Table 6.

Results Compositions E6 and E7 according to the invention surprisingly show a higher reflectivity retention after molding and exposure to light and heat for 12 days compared to Comparative Examples CE1-CE5.

  The data listed in Table 6 was observed between phosphite ester compounds such as Ultranox® 626 or Irgafos® P-EPQ and hindered amine compounds such as Nylostab® S-EED. It shows a synergistic effect well. The composition according to the invention relates both to the raw molded article and to the same material that has been subjected to light and heat treatment, intended to mimic the conditions under which the material may be exposed during the manufacture of LED devices. Achieves excellent optical properties.

  Comparative examples CE1 and CE3 provide evidence that phosphorus compounds alone are not sufficient to provide the excellent optical properties obtained by the examples according to the invention.

  Comparative Examples CE2 and CE5 are not efficient in the presence of a hindered amine compound to provide sufficient stability to the composition when exposed to both light and high heat (180 ° C.) for extended periods (12 days). Clearly show not.

  Examples E6 and E7 are a combination of a phosphorous compound (ULTRANOX® 626 stabilizer or IRGAFOS® P-EPQ) and a hindered amine compound (Nylostab® S-EED) Achieve unexpected results with respect to reflectivity retention after exposure to high heat. This result was obtained even when less total amount of additive was used when compared to the amount used in CE1 and CE3.

  Examples E6 and E7 according to the invention fulfill a broad set of requirements (particularly good processability, high dimensional stability, high mechanical strength) previously indicated, and surprisingly light and high Characterized by a reflectivity greater than 62% after heat treatment. These compositions are therefore very good candidates for the manufacture of LED components.

Claims (10)

At least one polyester;
At least one hindered amine compound;
A polymer composition comprising at least one phosphorus compound selected from the group consisting of phosphite esters, phosphonites and mixtures thereof,
A polymer composition wherein at least one phosphorus compound is present in an amount of 0.3 to 5% by weight, based on the total weight of the composition.   The polymer composition according to claim 1, wherein at least 50 mol% of the repeating units of the polyester are obtained by polycondensation of terephthalic acid and 1,4-cyclohexylenedimethanol.   The polymer composition according to any one of claims 1 to 2, wherein the polyester is poly (1,4-cyclohexylenedimethylene terephthalate).   4. The polymer composition according to claim 1, wherein the at least one hindered amine compound is present in an amount of 0.05 to 2% by weight, based on the total weight of the composition.   The polymer composition according to any one of claims 1 to 4, further comprising at least one white pigment. The white pigment is selected from _{TiO 2,} ZnS _{2, ZnO,} and BaSO _4, polymer composition according to claim 5.   The polymer composition according to any one of claims 1 to 6, further comprising at least one reinforcing filler.   8. A polymer composition according to claim 7, wherein the reinforcing filler is selected from glass fibers, wollastonite, carbon fibers, talc, mica and kaolin.   An article comprising the polymer composition according to any one of claims 1-8.   The article of claim 9, which is a component of an LED device.