WO2016105162A1 - Polyamide resin composition and moulded article produced from same - Google Patents

Abstract

The present invention concerns a polyamide resin composition and a moulded article produced from same, and the polyamide resin composition may comprise: (A) a polyamide resin; (B) a white pigment; (C) approximately 0.01 to approximately 10 parts by weight of a sodium phosphate salt, with respect to 100 parts by weight of the sum of the polyamide resin (A) and the white pigment (B); and (D) approximately 0.01 to approximately 10 parts by weight of magnesium oxide. The polyamide resin composition of the present invention has outstanding reflectance and anti-yellowing properties and thus has the advantage that the reflectance rate is maintained even as time passes.

Description

Polyamide Resin Compositions and Molded Articles Made therefrom

The present invention relates to a polyamide resin composition and a molded article prepared therefrom, and more particularly, to a polyamide resin composition excellent in reflectivity and yellowing resistance and a molded article prepared therefrom.

Polyamide resins have excellent performance in heat resistance, abrasion resistance, chemical resistance, and flame retardancy, and are used in a wide range of fields such as electric parts, electronic parts, and automobile parts.

These polyamide resins are rapidly replacing many conventional light sources due to their excellent energy efficiency and lifespan, and are reflectors, scramblers or housings, which are the accessories of light emitting diodes (LEDs), which are in the spotlight. ) Is used as a material.

The reflector for light emitting diode is a component material that improves luminous efficiency by reflecting light from the light emitting diode chip to the front while wrapping and protecting the light emitting diode chip from the outside. There is a problem that falls and the light extraction ability is also lowered.

Accordingly, a method of introducing an inorganic pigment having a large refractive index into a reflector material has been proposed. However, in the case of the above method, although the initial reflectance can be improved to some extent, there is a problem that color change occurs during molding and the reflectance decreases significantly with time, so that sufficient luminance cannot be obtained.

In addition, while attempting to produce a reflector with a ceramic different from the material, while the ceramic material is excellent in heat resistance and chemical resistance, there is a disadvantage in that the productivity is low.

Therefore, there is a need for a study of a polyamide resin composition capable of maintaining excellent reflectivity and yellow color change because the characteristics of reflectance and whiteness do not change even when used for a long time to extend the life of the light emitting diode illumination.

An object of the present invention is to solve such a conventional problem, and to provide a polyamide resin composition having excellent reflectivity and yellowing resistance.

In order to achieve the above object, the polyamide resin composition according to an embodiment of the present invention (A) polyamide resin; (B) white pigments; (C) about 0.01 to about 10 parts by weight based on 100 parts by weight of the sum of the polyamide resin (A) and the white pigment (B); And (D) about 0.01 to about 10 parts by weight of magnesium oxide.

The polyamide resin composition may comprise about 40 to about 95 weight percent of the polyamide resin (A) based on 100 weight percent of the polyamide resin (A) and the white pigment (B); And about 5 to about 60% by weight of the white pigment (B).

The polyamide resin (A) may be an aromatic polyamide resin.

The polyamide resin (A) may have a melting point of about 200 ° C to about 350 ° C.

The white pigment (B) may be selected from the group consisting of titanium oxide, zinc oxide, zinc sulfide, lead white, zinc sulfate, barium sulfate, calcium carbonate, aluminum oxide and combinations thereof.

The sodium phosphate salt (C) and the magnesium oxide (D) may be included in a weight ratio of about 1:10 to about 10: 1.

The sodium phosphate salt (C) may be selected from the group consisting of sodium pyrophosphate, sodium triphosphate, sodium tetrapolyphosphate, sodium pentapolyphosphate, sodium hexametaphosphate, and combinations thereof.

The concentration of magnesium ion (Mg ^{+ 2)} contained in the polyamide resin composition may be from about 60 to about 60,000ppm.

The molded article according to one embodiment of the present invention may be prepared from the polyamide resin composition described above.

The molded article may have an initial reflectance measured at 440 nm with a color difference meter of about 90 or more, and a reflectance measured at 440 nm after standing at a temperature of 85 ° C. and a relative humidity of 85% for 1,000 hours.

The molded article is a non-(R ₁ / R ₀₎ of the initial reflectance (R ₀₎ and then the temperature allowed to stand at 85 ℃, relative humidity 85% 1000 hours a reflectance measurement from the color difference to step 440nm (R ₁₎ measured at the color difference to step 440nm About 0.75 to about 0.99.

The molded article has an initial yellowness (Y ₀ ) of less than about 6.5 measured by a color difference meter, and yellowness measured by a color difference meter (Y ₁₎ after 144 hours at an initial yellowness (Y ₀ ), a temperature of 85 ° C., and a relative humidity of 85%. Ratio (Y ₁ / Y ₀ ) may be from about 1.5 to about 2.9.

The molded article may be a reflector for a light emitting diode (LED).

The polyamide resin composition according to the present invention is excellent in initial reflectance by simultaneously adding sodium phosphate salt and magnesium oxide, and maintains a high level of reflectance even after being left for a long time under constant temperature and constant humidity.

In addition, the polyamide resin composition according to the present invention has excellent yellowing resistance, and when applied as a reflector of a light emitting diode, it is possible to realize improved light extraction ability even for long-term use.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail. However, the present invention is not limited to the embodiments disclosed below, but can be implemented in various different forms, and only the embodiments make the disclosure of the present invention complete, and the general knowledge in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.

Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used in a sense that can be commonly understood by those skilled in the art. In addition, the terms defined in the commonly used dictionaries are not ideally or excessively interpreted unless they are specifically defined clearly.

Hereinafter, the polyamide resin composition according to an embodiment of the present invention will be described.

The polyamide resin composition according to the present invention contains (A) polyamide resin, (B) white pigment, (C) sodium phosphate salt and (D) magnesium oxide.

Each component of the polyamide resin composition according to an embodiment of the present invention will be described in detail.

(A) polyamide resin

Polyamide resin (A) is a basic resin which comprises a polyamide resin composition, Preferably an aromatic polyamide resin can be used.

The aromatic polyamide resin may have a structure including a benzene ring in the main chain and may be formed by using an aromatic dicarboxylic acid and an aliphatic or alicyclic diamine as a repeating unit.

The aromatic dicarboxylic acid unit is, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4- Derived from at least one selected from phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, 4,4'-oxydibenzoic acid, and diphenylmethane-4,4'-dicarboxylic acid. It may be.

The aliphatic diamine units are, for example, 1,6-hexanediamine, 1,7-heptane diamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1-butyl-1 , 2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1 , 4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5 -Pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1 , 6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2,2-diethyl-1,7-heptane diamine, 2,3-dimethyl-1,7-heptane diamine, 2,4-dimethyl-1,7-heptane diamine, and 2,5-dimethyl-1,7 It may be derived from at least one diamine selected from -heptane diamine.

In addition, the polyamide may have a melting point of about 200 ° C to about 350 ° C, preferably about 250 ° C to 320 ° C. When the melting point of the polyamide satisfies the above range, the heat resistance is excellent.

Specific examples of the polyamide include polytetramethylene adipamide (PA 46), polycaproamide / polyhexamethylene terephthalamide copolymer (PA 6 / 6T), polyhexamethylene adipamide / polyhexamethylene terephthalamide copolymer (PA 66 / 6T), polyhexamethylene adipamide / polyhexamethylene isophthalamide copolymer (PA 66 / 6I), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (PA 6T / 6I), Polyhexamethylene terephthalamide / polydodecaneamide copolymer (PA 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (PA66, 6T, 6I), poly Silylene Adipamide (PA MXD6), Polyhexamethylene Terephthalamide / Poly 2-methylpentamethylene Terephthalamide Copolymer (PA 6T, M5T), Polyhexamethylene Terephthalamide (PA 6T), Polynonnamethyl Lene terephthalamide (PA 9T), polydecamethylene terephthalamide (PA 10T), mixtures thereof, and the like.

Preferably, it may be polyhexamethylene terephthalamide (PA 6T) or polydecamethylene terephthalamide (PA 10T).

The polyamide resin may be included in an amount of about 40 wt% to about 95 wt%, preferably about 50 wt% to about 90 wt%, based on 100 wt% of the total polyamide resin and the white pigment. When the content of the polyamide resin is within the above range, the heat resistance or mechanical strength is excellent.

(B) white pigment

White pigment (B) can be used in the present invention to realize sufficient reflectance.

Specifically, the white pigment may be titanium oxide, zinc oxide, zinc sulfide, lead white, zinc sulfate, barium sulfate, calcium carbonate, or aluminum oxide, and may be used by mixing two or more kinds.

The white pigment may be used by treating with a silane coupling agent or a titanium coupling agent on its surface for stable bonding with the polyamide resin (A), and the silane coupling agent may be used in vinyltriethoxysilane, 2-aminopropyltri Methoxysilane, 2-glycidoxypropyltriethoxysilane, and the like.

The white pigment may be used by modifying the surface with an inorganic surface treatment agent or an organic surface treatment agent, the surface modification may be carried out a plurality of times.

The inorganic surface treatment agent may be aluminum oxide, silicon dioxide (silica), zirconium dioxide (zirconia), sodium silicate, sodium aluminate, sodium aluminum silicate, zinc oxide or mica. The organic surface treating agent may be polydimethylsiloxane, trimethylpropane or pentaerythritol. Preferably, aluminum oxide can be used.

The inorganic surface treating agent or the organic surface treating agent may be included in an amount of 0.1 to 1 parts by weight based on 100 parts by weight of the white pigment.

The white pigment may be included in an amount of about 5 wt% to about 60 wt%, preferably about 10 wt% to about 50 wt%, based on 100 wt% of the polyamide resin and the total amount of the white pigment. All of these compositions can be obtained.

(C) sodium phosphate salt

Sodium phosphate salt (C) is added in order to achieve sufficient reflectivity while at the same time realizing sufficient reflectivity.

The sodium phosphate salt is excellent in water stability and thermal stability and can be added to the polyamide resin composition to maintain whiteness even after constant temperature and humidity, and to reduce the decrease in reflectance, thereby achieving high reflectance and at the same time ensuring excellent heat resistance. .

The sodium phosphate salt is, for example, sodium pyrophosphate, sodium triphosphate, sodium tetrapolyphosphate, sodium tetrapolyphosphate, sodium pentapolyphosphate, and sodium hexametaphosphate (soate hexametaphosphate). It may include any one or a mixture of two or more selected from.

Sodium phosphate salt in the present invention may preferably comprise sodium pyrophosphate or sodium hexametaphosphate. When the sodium phosphate salt is used, even when the molded article manufactured from the resin composition is exposed to high temperature and high humidity conditions for a long time, the reflectance and the light efficiency are not lowered, and excellent light stability and discoloration resistance can be exhibited.

The sodium phosphate salt may be used that is surface-treated with a surface treatment agent to improve the adhesion and dispersibility with the polyamide resin.

Examples of the surface treatment agent include silane coupling agents such as silane and epoxy silane, titanium coupling agents, organic acids such as organic acids, polyols, and silicon.

The sodium phosphate salt may be included in an amount of about 0.01 to about 10 parts by weight, preferably about 0.1 to about 7 parts by weight, based on 100 parts by weight of the polyamide resin and the white pigment. If the sodium phosphate salt is less than 0.01 parts by weight, the reflectivity may be lowered. If it exceeds 10 parts by weight, impact resistance and yellowing resistance may be lowered.

(D) magnesium oxide

By adding magnesium oxide (D) together with the sodium phosphate salt (C), it is possible to suppress the decrease in the light reflectance of the polyamide resin composition and to improve the reflectance and the retention of the reflectance.

The magnesium oxide has an ultraviolet absorbing effect, excellent in the ability to trap radicals, and when used in combination with the sodium phosphate salt to suppress the increase in yellowness can further improve the reflectance.

By using sodium phosphate salt and magnesium oxide simultaneously, the inventors of the present invention not only realize excellent whiteness of the polyamide resin composition, but also discoloration does not occur well even after long-term exposure to light, so that the light extraction ability can be maintained to a similar level as the initial stage. I found out.

The magnesium oxide may be included in an amount of about 0.01 to about 10 parts by weight, preferably about 0.1 to about 7 parts by weight, based on 100 parts by weight of the polyamide resin and the white pigment. When the content of magnesium oxide is less than 0.01 parts by weight, it is difficult to prevent discoloration when the molded article prepared from the polyamide resin composition is exposed to light, and when the content is more than 10 parts by weight, the effect of improving the reflectance is insignificant.

In addition, the polyamide resin composition including magnesium oxide may include magnesium ions (Mg ^{2 +} ) of 60 to 60,000 ppm concentration, preferably magnesium ions (Mg ^{2 +} ) of 600 to 40,000 ppm concentration. can do. Within this range, discoloration prevention and reflectance improvement effects are excellent. In the composition of the present invention, the sodium phosphate salt and the magnesium oxide may be included in a weight ratio of about 1:10 to about 10: 1, preferably in a weight ratio of about 1: 5 to about 5: 1. Can be. When the content ratio of sodium phosphate salt and the magnesium oxide satisfies the above range, the effect of preventing discoloration and improving the reflectance retention is more excellent.

The polyamide resin composition may optionally further include an additive according to its use. The additive may further include a filler, a flame retardant, a lubricant, a plasticizer, a heat stabilizer, an antioxidant, a light stabilizer, or a colorant, and may be used by mixing two or more kinds according to the properties of the final molded product.

The filler may be added to improve the mechanical properties, heat resistance and dimensional stability of the polyamide resin composition. The fillers include carbon fibers, glass fibers, boron fibers, glass beads, glass flakes, carbon black, talc, clay, kaolin, talc, mica, calcium carbonate, and mixtures thereof. Calcium whisker, aluminum borate whisker, zinc oxide whisker, calcium whisker and the like.

Preferably, glass fibers may be used, and the glass fibers are conventional ones used in the art, and those having a diameter of 8 to 20 μm and a length of 1.5 to 8 mm may be used. When the diameter of the glass fiber is in the above range can be obtained an effect of excellent strength reinforcement, when the length of the glass fiber has the above range it is easy to put into the processing equipment such as an extruder and the strength reinforcement effect can also be greatly improved.

The glass fiber may have an aspect ratio of less than 1.5, and specifically, a circular shape having an aspect ratio of 1 may be used. The aspect ratio is then defined as the ratio of the longest diameter to the smallest diameter in the cross section of the glass fiber. When using a glass fiber having an aspect ratio of the cross section, it is possible to lower the unit cost of the product in terms of cost, and to improve the dimensional stability and appearance by using a glass fiber having a circular cross section.

The flame retardant is a material for reducing combustibility, and includes a phosphate compound, a phosphite compound, a phosphonate compound, a polysiloxane, a phosphazene compound, a phosphinate compound or a melamine compound It may include at least one of, but is not limited thereto.

The lubricant is a material that helps the flow or movement of the resin composition by lubricating the metal surface in contact with the polyamide resin composition during processing, molding, extrusion, may be used a commonly used material.

The plasticizer is a material that increases the flexibility, processing workability, or expandability of the polyamide resin composition, and may be a material commonly used.

The heat stabilizer is a material that suppresses thermal decomposition of the polyamide resin composition when kneading or molding at a high temperature, and may be a material that is commonly used.

The antioxidant is a substance that prevents decomposition of the resin composition and loss of intrinsic properties by inhibiting or blocking a chemical reaction between the polyamide resin composition and oxygen, and is a phenol type, phosphite type, thioether type or amine type antioxidant. It may include at least one of, but is not limited thereto.

The light stabilizer is a material for inhibiting or blocking the polyamide resin composition from being decomposed from ultraviolet rays and changing color or losing mechanical properties, preferably titanium oxide.

The colorant may be used conventional pigments or dyes.

The additive may be included in about 1 to 15 parts by weight based on 100 parts by weight of polyamide resin.

The polyamide resin composition according to the present invention can be prepared by a known method, for example, in the form of pellets by mixing the components of the present invention and other additives at the same time and then melt extrusion in an extruder. Can be.

The molded article according to one embodiment of the present invention may be prepared from the polyamide resin composition described above. The polyamide resin composition is excellent in reflectance, retention of reflectance and yellowing resistance.

The molded article may have an initial reflectance of about 90 or more measured at 440 nm with a color difference meter, and a reflectance measured at 440 nm after 1,000 hours at a temperature of 85 ° C. and a relative humidity of 85% of about 70 or more, preferably about 70 to about 90 , More preferably about 73 to about 90.

In addition, the molded article is a ratio (R ₁ / R ₀ ) of the initial reflectance (R ₀ ) measured at 440 nm with a color difference meter and the reflectance (R ₁ ) measured at 440 nm with a color difference meter after 1,000 hours at 85 ° C. and 85% relative humidity _. ) May be about 0.75 to about 0.99, preferably about 0.78 to about 0.99.

In addition, the molded article has an initial yellowness (Y ₀ ) measured by a color difference meter of less than about 6.5, and the yellowness measured by a color difference meter after 144 hours at an initial yellowness (Y ₀ ), a temperature of 85 ° C., and a relative humidity of 85% ( Y ₁₎ may be a ratio (Y ₁ / Y ₀₎ is about 1.5 to about 2.9. Preferably, the initial yellowness (Y ₀₎ is from about 6 or less, the ratio (Y ₁ / Y ₀₎ of the Y ₁ to Y ₀ may be about 1.5 to about 2.8.

The polyamide resin composition according to the present invention is excellent in reflectance, retention of reflectance, and yellowing resistance, and can be used without limitation in a molded article requiring such properties, and specifically, may be usefully applied as a reflector for a light emitting diode (LED). Can be.

Hereinafter, the result of having performed the experiment for demonstrating the outstanding effect of the polyamide resin composition of this invention is shown.

The component used for the polyamide resin composition of the following Example and a comparative example is as follows.

(a) polyamide resin

An aromatic polyamide resin having a melting point of 305 ° C / 295 ° C and an intrinsic viscosity (IV) of 0.78 dl / g was used. (The intrinsic viscosity was measured using a Ubbelodhde viscometer at 25 ° C. after dissolving the sample in 98% sulfuric acid solution.)

(b) white pigment

A product of SAOMAI SM2515, titanium oxide of Wooshin Peakment, was used.

(c) sodium phosphate salt

Sodium hexametaphosphate from INNOPHOS was used.

(d) magnesium oxide

Konarmsma's magnesium oxide, STARMAG 150, was used.

(e) antioxidants

A product of Irganox 1010, a hindered phenolic antioxidant of Ciba Geigy, was used.

The components shown in Table 1 were put into a mixer and dry mixed. Then, using a twin screw extruder having a diameter of 36 mm was processed at a barrel temperature of 250 ℃ to 310 ℃ to prepare a thermoplastic resin composition in the form of pellets through the extruder. The prepared pellets were dried at 80 ° C. for at least 4 hours, and then the specimens were injected.

The content of each component listed in Table 1 is based on (a) and (b) 100% by weight of the total (a) and (b), the content of (c), (d) and (e) A total of 100 parts by weight of (a) and (b) was described, and the content of magnesium ions (Mg ²⁺ ) relative to the total polyamide resin composition was described in ppm.

Example Comparative example One 2 3 4 One 2 3 4 (a) 60 60 60 60 60 60 60 60 (b) 40 40 40 40 40 40 40 40 (c) 0.5 0.5 3 3 3 3 - - (d) 0.5 3 0.5 3 - - 3 3 (e) - - - - - 0.5 - 0.5 Mg ²⁺ content (ppm) 3,000 18,000 3,000 18,000 - - 18,000 18,000

Reflectance and yellowing resistance of the polyamide resin compositions of Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated. The evaluation method of the evaluation item is as follows, and the evaluation result of each item is described in Table 2.

<Evaluation of Reflectance>

Minolta 3600D CIE Lab. The initial reflectance (SCI, specular component included) of 440 nm was measured with a color difference meter, and the reflectance was measured again after 1,000 hours at 85 ° C. and 85% relative humidity to evaluate the retention of the reflectance.

<Yellowing resistance>

Minolta 3600D CIE Lab. The initial yellowness (Yellow Index) was measured by a color difference meter, and the yellowness was measured again after being left for 144 hours at a temperature of 85 ° C. and a relative humidity of 85% to evaluate the change in yellowness.

Example Comparative example One 2 3 4 One 2 3 4 reflectivity R ₀ 94.5 94.1 94.9 94.8 93.4 93.6 93.0 93.2 R ₁ 75.8 76.4 74.5 75.6 65.8 66.1 66.5 66.7 R ₁ / R ₀ 0.80 0.81 0.79 0.80 0.70 0.71 0.72 0.72 Yellow road Y ₀ 5.0 5.2 4.6 4.8 7.2 6.9 6.6 6.4 Y ₁ 11.9 10.5 12.8 12.3 20.7 20.3 19.8 19.5 Y ₁ / Y ₀ 2.38 2.02 2.78 2.56 2.88 2.94 3.00 3.05

From Table 1 and Table 2, it was found that the polyamide resin compositions of Examples 1 to 4 were excellent in both reflectance and yellowness.

When magnesium oxide is not added (Comparative Example 1), or when sodium phosphate salt is not added (Comparative Example 3), the initial reflectance is smaller than that of the embodiments, and the reflectance is long when left at a constant temperature and constant humidity. It was greatly dropped, and the change in the initial yellowness and the yellowness was also greatly measured, indicating that the yellowing discoloration resistance was remarkably decreased and the retention of the reflectance was lowered.

Also, an example in which magnesium oxide and sodium phosphate salt were added simultaneously, even though antioxidant was added instead of magnesium oxide (Comparative Example 2) or antioxidant was added instead of sodium phosphate salt (Comparative Example 4). The reflectance was measured lower than that of the light bulbs, and the initial yellowness was also high, and the color variation also increased with time, and thus, the initial reflectance was greatly decreased and the light extraction ability was deteriorated with time.

Thus, it can be seen that sodium phosphate salt and magnesium oxide have a major influence on the reflectivity and yellowing resistance of the polyamide resin composition, and the retention of reflectance can be maintained at an excellent level by adding an optimal content of sodium phosphate salt and magnesium oxide. .

The scope of the present invention is not limited to the above-described embodiment, but may be embodied in various forms of embodiments within the scope of the appended claims. Without departing from the gist of the present invention as claimed in the claims, any person having ordinary skill in the art to which the present invention pertains is considered to be within the scope of the claims described in the present invention to various extents which can be modified.

Claims (13)

(A) polyamide resin; (B) white pigments; To 100 parts by weight of the total of the polyamide resin (A) and the white pigment (B), (C) about 0.01 to about 10 parts by weight of sodium phosphate salt; And (D) Polyamide resin composition comprising about 0.01 to about 10 parts by weight of magnesium oxide. The method of claim 1, To 100% by weight of the sum of the polyamide resin (A) and the white pigment (B), About 40 to about 95 weight percent of the polyamide resin (A); And Polyamide resin composition comprising about 5 to about 60% by weight of the white pigment (B). The method of claim 1, The polyamide resin (A) is a polyamide resin composition is an aromatic polyamide resin. The method of claim 2, The polyamide resin (A) has a melting point of about 200 ℃ to about 350 ℃. The method of claim 1, The white pigment (B) is a polyamide resin composition selected from the group consisting of titanium oxide, zinc oxide, zinc sulfide, lead white, zinc sulfate, barium sulfate, calcium carbonate, aluminum oxide and combinations thereof. The method of claim 1, Wherein said sodium phosphate salt (C) and said magnesium oxide (D) are included in a weight ratio of about 1:10 to about 10: 1. The method of claim 1, The sodium phosphate salt (C) is polyamide resin composition selected from the group consisting of sodium pyrophosphate, sodium triphosphate, sodium tetrapolyphosphate, sodium pentapolyphosphate, sodium hexametaphosphate and combinations thereof. The method of claim 1, The polyamide resin composition having a concentration of magnesium ions (Mg ^{2 +} ) contained in the polyamide resin composition is about 60 to about 60,000 ppm. The molded article manufactured from the polyamide resin composition of any one of Claims 1-8. The method of claim 9, The molded article has an initial reflectance of about 90 or more measured at 440 nm with a color difference meter, and a reflectance measured at 440 nm of about 70 or more after 1,000 hours at 85 ° C. and 85% relative humidity. The method of claim 9, The molded article is a non-(R ₁ / R ₀₎ of the initial reflectance (R ₀₎ and then the temperature allowed to stand at 85 ℃, relative humidity 85% 1000 hours a reflectance measurement from the color difference to step 440nm (R ₁₎ measured at the color difference to step 440nm Molded article that is about 0.75 to about 0.99. The method of claim 9, The molded article has an initial yellowness (Y ₀ ) of less than about 6.5 measured by a color difference meter, and an yellowness (Y ₁₎ measured by a color difference meter after 144 hours at an initial yellowness (Y ₀ ), a temperature of 85 ° C., and a relative humidity of 85%. Molded article having a ratio (Y ₁ / Y ₀ ) of about 1.5 to about 2.9. The method of claim 9, The molded article is a molded article is a reflector for a light emitting diode (LED).