JP2020019914A - Polyester resin composition for reflector and reflector - Google Patents

Abstract

To provide a polyester resin composition for a reflector that is extremely low in discoloration and reflectance reduction caused by heat treatment for a short period of time and can give a reflector having less discoloration and a small reduction in reflectance after exposure to heat or light over a long period of time.SOLUTION: The polyester resin composition for a reflector includes: 30 pts.mass to 80 pts.mass of (A) a polyester resin having a melting point (Tm) or a glass transition temperature (Tg) of 270°C or higher; 0.01 pt.mass to 5 pts.mass of (B) an alkali metal salt of hypophosphorous acid; 5 pts.mass to 50 pts.mass of (C) a white pigment; and 1 pt.mass to 50 pts.mass of (D) an inorganic filler (provided that the total sum of (A), (B), (C) and (D) is 100 pts.mass).SELECTED DRAWING: None

Description

  The present invention relates to a polyester resin composition for a reflector and a reflector.

  Light sources such as light-emitting diodes (LEDs) and organic ELs are widely used for lighting and display backlights, taking advantage of their features (eg, low power and long life). In order to efficiently use light from these light sources, reflectors have been used in various aspects.

  For example, the LED element has a housing portion (reflective material) provided on a substrate and having a space for mounting the LED, an LED mounted in the space, and a sealing member for sealing the LED. . Such an LED element includes, for example, 1) a step of forming a housing portion on a substrate, 2) a step of disposing an LED inside the housing portion, and electrically connecting the LED and the substrate, and 3) an LED. It is manufactured through a step of sealing with a sealing agent.

  In the sealing step (3), the sealing agent is heated to 100 to 200 ° C. and thermally cured. Therefore, the housing is exposed to a high temperature of 100 to 200 ° C. Further, in the 2) LED mounting step, a reflow soldering step is performed to mount the LED on the board. In this case, the housing is also exposed to a temperature of 250 ° C. or more. The reflecting material such as the housing is required to be able to maintain the reflectance even after passing through such a temperature. In addition, the reflective material is required to be able to maintain the reflectance even when exposed to heat or light generated under the use environment (for example, heat or light generated from the LED) for a long time.

  In response to these demands, Patent Document 1 discloses polycyclohexylene dimethylene terephthalate, an inorganic filler such as glass fiber, a white pigment such as titanium oxide, a phenolic antioxidant, Compositions comprising an antioxidant stabilizer such as triphenyl phosphate are disclosed. Patent Document 1 states that the composition has an increased reflectance at high temperatures.

  Patent Documents 2 and 3 disclose polyester resins such as polycyclohexylene dimethylene terephthalate, inorganic fillers such as wollastonite, white pigments such as titanium oxide, and phosphorus such as sodium pyrophosphate and sodium dihydrogen phosphate. And a sodium acid salt. It is said that the resin compositions of Patent Literatures 2 and 3 contain a sodium phosphate salt so that a decrease in reflectance can be reduced even when stored for a long period of time under a high-temperature and high-humidity condition. Patent Document 4 discloses a polyester resin such as polycyclohexylene dimethylene terephthalate, an alkaline earth metal hypophosphite such as calcium hypophosphite, a white pigment such as titanium oxide, and a reinforcing material such as glass fiber. A resin composition is disclosed. It is said that the resin composition can reduce a decrease in reflectance by including an alkaline earth metal hypophosphite salt.

JP 2006-504459 A US Patent Application Publication No. 2014/0187662 JP-A-2005-105379 International Publication No. WO 2017/2091782

  However, the resin composition disclosed in Patent Literature 1 may cause discoloration due to heat or light, and it is not possible to sufficiently suppress a decrease in reflectance when exposed to heat or light. Although the cause is not clear, it is considered that organic antioxidants such as phenolic antioxidants and triphenyl phosphate are themselves responsible for coloring.

  On the other hand, the resin compositions disclosed in Patent Documents 2 to 4 contain an alkaline earth metal hypophosphite such as sodium phosphate or calcium hypophosphite, which are inorganic compounds, but are still discolored by heat or light. And so on, and it was not possible to sufficiently suppress a decrease in reflectance when exposed to heat or light.

  Furthermore, since the reflectance of the resin compositions disclosed in Patent Documents 1 to 4 is reduced by a heating process of 170 ° C. × 2 h (a short-time heating process) received in a manufacturing process of an LED element, the brightness of the LED is short. It is thought to be the cause of the decrease.

  Therefore, there is a demand for a reflective material that has little discoloration and a small decrease in reflectance even when exposed to heat received in a manufacturing process or a mounting process of an LED element, or heat or light received from a light source in a usage environment. . Further, since the performance of light sources such as high brightness of LEDs has been improved, there is a demand for further improvement in whiteness and reflectivity of reflectors.

  The present invention has been made in view of the above circumstances, is very little discoloration and a decrease in reflectance due to short-term heat treatment, and even if exposed to heat or light for a long period of time, there is little discoloration and reflectance. An object of the present invention is to provide a polyester resin composition for a reflector, which can provide a reflector having a small decrease.

[1] A polyester resin (A) having a melting point (Tm) or glass transition temperature (Tg) of at least 270 ° C. measured by a differential scanning calorimeter (DSC) of at least 30 parts by mass and at most 80 parts by mass, and hypophosphorous acid 0.01 to 5 parts by mass of the alkali metal salt (B), 5 to 50 parts by mass of the white pigment (C), and 1 to 50 parts by mass of the inorganic filler (D). A polyester resin composition for a reflector, including (but the total of (A), (B), (C) and (D) is 100 parts by mass).
[2] The polyester resin composition for a reflector according to [1], wherein the alkali metal hypophosphite (B) is a sodium hypophosphite.
[3] The content of the alkali metal hypophosphite (B) is 0.12 parts by mass or more and 3.3 parts by mass or less based on 100 parts by mass of the polyester resin (A). ] Or the polyester resin composition for a reflective material according to [2].
[4] The polyester resin (A) includes a component unit (a1) derived from a dicarboxylic acid and a component unit (a2) derived from a dialcohol, and the component unit (a1) derived from the dicarboxylic acid includes: 30 mol% or more and 100 mol% or less of the component unit derived from terephthalic acid with respect to 100 mol% in total of the component unit (a1) derived from dicarboxylic acid, and the component derived from aromatic dicarboxylic acid other than terephthalic acid. The component unit (a2) derived from the above-mentioned dialcohol contains 0 mol% or more and 70 mol% or less, and the component unit derived from an alicyclic dialcohol having 4 to 20 carbon atoms and an aliphatic dialcohol. The polyester resin composition for a reflector according to any one of [1] to [3], comprising at least one of the component units derived from:
[5] The polyester resin composition for a reflective material according to [4], wherein the component unit (a2) derived from the dialcohol includes a component unit derived from an alicyclic dialcohol having a cyclohexane skeleton.
[6] The component unit (a2) derived from the dialcohol is a component unit derived from 1,4-cyclohexanedimethanol in an amount of 30 mol% based on a total of 100 mol% of the component unit (a2) derived from the dialcohol. The polyester resin composition for a reflective material according to [4] or [5], comprising from not less than 100 mol% and not more than 100 mol%, and from 0 mol% to 70 mol% of a component unit derived from the aliphatic dialcohol.
[7] The polyester resin composition for a reflector according to any one of [1] to [6], wherein the inorganic filler (D) is a glass fiber.
[8] A phenolic antioxidant (E) is further contained, and the content ratio (B) / (E) of the alkali metal hypophosphite (B) and the phenolic antioxidant (E) is 0. The polyester resin composition for a reflector according to any one of [1] to [7], which is 1 or more and less than 2.
[9] The polyester resin composition for a reflective material according to any one of [1] to [8],
Reflective material.
[10] The reflector according to [9], which is a reflector for a light emitting diode element.

  ADVANTAGE OF THE INVENTION According to this invention, the discoloration and the fall of a reflectance by heat processing for a short period are very little, and even if it is exposed to heat and light for a long period of time, the discoloration is little and the reflection material with a little fall of a reflectance can be provided. A polyester resin composition for a reflector can be provided.

  As described above, a polyester resin having a high melting point and a high crystallization rate, such as polycyclohexane dimethylene terephthalate (PCT), is used for the resin composition for the reflector. However, in particular, polycyclohexane dimethylene terephthalate has tertiary carbon derived from a cyclohexane ring, and thus easily undergoes discoloration during high-temperature treatment and deterioration during light irradiation.

  In contrast, by incorporating organic antioxidants such as phenolic antioxidants and organic phosphorus antioxidants, it is possible to suppress the decomposition and discoloration of the resin. Therefore, it is difficult to achieve both suppression of resin decomposition and suppression of coloring by an antioxidant. Further, the alkaline earth metal hypophosphite has less decomposition and coloring of the resin than the organic antioxidant, but is still insufficient.

  The present inventors have conducted intensive studies and found that by adding a predetermined amount of an alkali metal hypophosphite (B), a conventional resin composition containing only an organic antioxidant or an alkaline earth hypophosphite was used. Even if exposed to high-temperature heat such as reflow heat treatment or light under a use environment for a long time than a resin composition containing a metal salt, for example, without decomposing the resin itself, It has been found that discoloration can be suppressed and a decrease in reflectance can be suppressed.

  In particular, since the alkali metal hypophosphite (B) has a smaller molecular size than the alkaline earth metal hypophosphite, it is easily dispersed in the polyester resin (A), and after heating for a short period of time, and It is considered that an antioxidant effect can be easily exerted even when heating or light irradiation is performed for a period. Thereby, it is considered that the decomposition of the resin can be suppressed to a high degree without causing coloring due to itself, and the decrease in reflectance after long-time heating or light irradiation can be suppressed to a higher degree.

  Further, the reason why the alkali metal hypophosphite (B) has less decrease in the reflectance after heating than the alkaline earth metal hypophosphite is that, in addition to the aforementioned molecular size, Further, it is considered that there are the following reasons. That is, unlike the alkaline earth metal hypophosphite, the alkali metal hypophosphite (B) is hydrated, so that it is easily dehydrated at the time of heating. It is considered that the decomposition of the polyester resin (A) by the compound can be suppressed to a higher degree. The present invention has been made based on these findings.

1. Polyester Resin Composition for Reflecting Material The polyester resin composition for a reflecting material of the present invention comprises a polyester resin (A), an alkali metal hypophosphite (B), titanium oxide (C), and an inorganic filler (D). ).

1-1. Polyester resin (A)
The polyester resin (A) contains a component unit (a1) derived from a dicarboxylic acid and a component unit (a2) derived from a dialcohol.

  The component unit (a1) derived from dicarboxylic acid includes a component unit derived from terephthalic acid of 30 mol% or more and 100 mol% or less, and a component unit derived from an aromatic dicarboxylic acid other than terephthalic acid of 0 mol% or more and 70 mol%. % Or less. The proportion of the component unit derived from terephthalic acid contained in the component unit (a1) derived from dicarboxylic acid is more preferably 40 mol% or more and 100 mol% or less, and still more preferably 60 mol% or more and 100 mol% or less. It is possible. When the content of the component unit derived from terephthalic acid is high, the heat resistance of the polyester resin composition is further increased. The proportion of the component unit derived from an aromatic dicarboxylic acid other than terephthalic acid contained in the component unit (a1) derived from a dicarboxylic acid is more preferably 0 mol% or more and 60 mol% or less, and still more preferably 0 mol%. It can be at least 40 mol%. However, the total amount of the component units (a1) derived from dicarboxylic acid is set to 100 mol%.

  The component unit (a1-1) derived from terephthalic acid may be a component unit derived from terephthalic acid or terephthalic acid ester. The terephthalic acid ester is preferably an alkyl ester of terephthalic acid having 1 to 4 carbon atoms, examples of which include dimethyl terephthalate.

  Examples of the component unit (a1-2) derived from an aromatic dicarboxylic acid other than terephthalic acid include component units derived from isophthalic acid, 2-methylterephthalic acid, naphthalenedicarboxylic acid and a combination thereof, and aromatic units thereof. Component units derived from esters of dicarboxylic acids (preferably alkyl esters of aromatic dicarboxylic acids having 1 to 4 carbon atoms) are included.

  The component unit (a1) derived from a dicarboxylic acid is, together with the above component units, a small amount of a component unit derived from an aliphatic dicarboxylic acid or a component unit derived from a polyvalent carboxylic acid having three or more carboxylic acid groups in a molecule. May be further included. The ratio of the component unit derived from the aliphatic dicarboxylic acid and the component unit derived from the polycarboxylic acid contained in the component unit (a1) derived from the dicarboxylic acid may be, for example, 10 mol% or less in total.

  The number of carbon atoms of the aliphatic dicarboxylic acid is not particularly limited, but is preferably 4 or more and 20 or less, and more preferably 6 or more and 12 or less. Examples of aliphatic dicarboxylic acids include adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, undecanedicarboxylic acid and dodecanedicarboxylic acid. Among them, adipic acid is preferred. Examples of polycarboxylic acids include tribasic acids, including trimellitic acid and pyromellitic acid, and polybasic acids.

  The component unit (a2) derived from a dialcohol preferably contains a component unit derived from an alicyclic dialcohol having 4 to 20 carbon atoms and / or a component unit derived from an aliphatic dialcohol.

  The component unit (a2-1) derived from the alicyclic dialcohol can increase the heat resistance of the polyester resin composition and reduce the water absorption. Examples of alicyclic dialcohols include dialcohols having an alicyclic hydrocarbon skeleton having 4 to 20 carbon atoms, such as 1,3-cyclopentanediol, 1,3-cyclopentanedimethanol, 1,4 -Cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-cycloheptanediol and 1,4-cycloheptanedimethanol. Among them, a compound having a cyclohexane skeleton is preferable, and 1,4-cyclohexanedimethanol is more preferable, from the viewpoint that the heat resistance of the polyester resin composition is further increased, the water absorption is further reduced, and the availability is easy. .

  The alicyclic dialcohol has isomers such as a cis / trans structure, but from the viewpoint of further improving the heat resistance of the polyester resin composition, the polyester resin (A) is preferably composed of an alicyclic dialcohol having a trans structure. It is preferable to include more component units derived from Therefore, the cis / trans ratio of the component unit derived from the alicyclic dialcohol is preferably 50/50 to 0/100, and more preferably 40/60 to 0/100.

  The component unit (a2-2) derived from the aliphatic dialcohol further increases the melt fluidity of the polyester resin composition. Examples of the aliphatic dialcohol include ethylene glycol, trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol and dodecamethylene glycol.

  The component unit (a2) derived from a dialcohol is a component unit (a2-1) derived from an alicyclic dialcohol and the component unit (a2-2) derived from an aliphatic dialcohol alone. It may include, or may include both. The component unit (a2) derived from a dialcohol is a component unit derived from an alicyclic dialcohol (preferably a component unit derived from a dialcohol having a cyclohexane skeleton, more preferably derived from 1,4-cyclohexanedimethanol). It is preferable that the composition contains 30 mol% or more and 100 mol% or less, and 0 mol% or more and 70 mol% or less of the component unit derived from the aliphatic dialcohol. Component unit derived from alicyclic dialcohol contained in component unit (a2) derived from dialcohol (preferably component unit derived from dialcohol having cyclohexane skeleton, more preferably derived from 1,4-cyclohexanedimethanol) Is more preferably 50 mol% or more and 100 mol% or less, and still more preferably 60 mol% or more and 100 mol% or less. The proportion of the component unit derived from the aliphatic dialcohol contained in the component unit (a2) derived from the dialcohol is more preferably 0 mol% or more and 50 mol% or less, and still more preferably 0 mol% or more and 40 mol%. It is as follows. However, the total amount of the component units (a2) derived from the dialcohol is set to 100 mol%.

  The component unit (a2) derived from a dialcohol may further include a small amount of a component unit derived from an aromatic diol, together with the above-described component unit. Examples of aromatic dialcohols include bisphenol, hydroquinone and 2,2-bis (4-β-hydroxyethoxyphenyl) propane. The proportion of the component unit derived from the aromatic dialcohol contained in the component unit (a2) derived from the dialcohol may be, for example, 10 mol% or less.

  The melting point (Tm) or glass transition temperature (Tg) of the polyester resin (A) measured by a differential scanning calorimeter (DSC) is 270 ° C. or more. When the melting point or the glass transition temperature is 270 ° C. or higher, discoloration or deformation due to heat of the molded article (reflecting material) of the polyester resin composition can be suppressed even when exposed to a high temperature in, for example, a reflow soldering step. The melting point (Tm) or glass transition temperature (Tg) of the polyester resin (A) is preferably 350 ° C. or less. When the melting point or the glass transition temperature is 350 ° C. or lower, decomposition of the polyester resin (A) is easily suppressed during melt molding. The melting point (Tm) or glass transition temperature (Tg) of the polyester resin (A) measured by a differential scanning calorimeter (DSC) is more preferably 280 ° C or more and 335 ° C or less.

  The melting point of the polyester resin (A) can be measured by a differential scanning calorimeter (DSC) in accordance with JIS-K7121. Specifically, X-DSC7000 (manufactured by SII) is prepared as a measuring device. A pan for DSC measurement in which a sample of the polyester resin (A) was sealed was set in this apparatus, the temperature was increased to 320 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere, and the temperature was maintained for 5 minutes. The temperature is lowered to 30 ° C. by measuring the temperature at 10 ° C./min. Then, the temperature at the peak top of the endothermic peak at the time of temperature rise is defined as “melting point”.

  The intrinsic viscosity [η] of the polyester resin (A) is preferably from 0.3 dl / g to 1.2 dl / g. When the intrinsic viscosity is in the above range, the fluidity during molding of the polyester resin composition is good, and the mechanical strength is also excellent. The limiting viscosity of the polyester resin (A) can be adjusted by, for example, the degree of progress of the polycondensation reaction (polymerization temperature, polymerization time) or the addition of a molecular weight modifier (such as a monofunctional carboxylic acid or a monofunctional alcohol). .

The intrinsic viscosity [η] of the polyester resin (A) can be measured by the following procedure.
The polyester resin (A) is dissolved in a mixed solvent of 50/50% by mass of phenol and tetrachloroethane to prepare a sample solution. The falling time of the obtained sample solution is measured using an Ubbelohde viscometer at 25 ° C. ± 0.05 ° C., and the intrinsic viscosity [η] is calculated by applying the following equation.
[Η] = ηSP / [C (1 + kηSP)]

In the above formula, each algebra or variable represents the following.
[Η]: Intrinsic viscosity (dl / g)
ηSP: specific viscosity C: sample concentration (g / dl)
k: constant (gradient obtained by measuring the specific viscosities of samples (three or more points) having different solution concentrations, plotting the solution concentration on the horizontal axis and plotting ηsp / C on the vertical axis)

ηSP is obtained by the following equation.
ηSP = (t−t0) / t0

In the above formula, each variable represents the following.
t: Number of seconds during which the sample solution flows down (seconds)
t0: Number of seconds during which the solvent flows down (seconds)

  The polyester resin (A) may be manufactured by a known method, or a commercially available product may be purchased. For example, the polyester resin (A) may be produced by reacting a dicarboxylic acid component and a dialcohol component in the presence of a molecular weight modifier as required. Thereby, the intrinsic viscosity [η] of the polyester resin (A) may be adjusted to the above range.

  Examples of molecular weight regulators include monocarboxylic acids and monoalcohols. Examples of monocarboxylic acids include aliphatic monocarboxylic acids having 2 to 30 carbon atoms, aromatic monocarboxylic acids, and alicyclic monocarboxylic acids. In addition, the aromatic monocarboxylic acid and the alicyclic monocarboxylic acid may have a substituent in a cyclic structure portion. Examples of aliphatic monocarboxylic acids include acetic, propionic, butyric, valeric, caproic, caprylic, lauric, tridecyl, myristic, palmitic, stearic, oleic and linoleic acids. It is. Examples of aromatic monocarboxylic acids include benzoic acid, toluic acid, naphthalene carboxylic acid, methyl naphthalene carboxylic acid and phenylacetic acid. Examples of alicyclic monocarboxylic acids include cyclohexanecarboxylic acid.

  The amount of the molecular weight modifier added is 0 mol or more and 0.07 mol or less, preferably 0 mol or more and 0.05 mol or less, based on 1 mol of the total amount of the dicarboxylic acid component when the dicarboxylic acid component and the dialcohol component are reacted. Mol or less.

  The content of the polyester resin (A) in the polyester resin composition of the present invention is the sum of the polyester resin (A), the alkali metal hypophosphite (B), the titanium oxide (C) and the inorganic filler (D). When the amount is 100 parts by mass, the amount is preferably from 30 parts by mass to 80 parts by mass. When the content of the polyester resin (A) is at least 30 parts by mass, a polyester resin composition for a reflector excellent in heat resistance that can withstand a reflow soldering step or the like without impairing the moldability is easily obtained. When the total content of the polyester resin (A), the alkali metal hypophosphite (B), the titanium oxide (C) and the inorganic filler (D) is 100 parts by mass, the content of the polyester resin (A) is 40 parts by mass. It is more preferably from 70 parts by mass to 70 parts by mass, and further preferably from 50 parts by mass to 60 parts by mass.

1-2. Alkali metal hypophosphite (B)
The alkali metal hypophosphite (B) is an alkali metal hypophosphorous acid (a metal salt of Group 2 of the periodic table). The alkali metal hypophosphite (B) may be an intramolecular condensate or an intermolecular condensate. The alkali metal hypophosphite (B) may be a hydrate or an anhydride.

  Examples of the alkali metal hypophosphite include sodium hypophosphite, potassium hypophosphite, and the like. Among them, sodium hypophosphite is more preferred because of its high reducing action.

  The average particle size of the alkali metal hypophosphite (B) is preferably from 0.01 μm to 1500 μm. When the average particle size of the alkali metal hypophosphite (B) is in the above range, it can be easily dispersed uniformly in the polyester resin (A). The average particle diameter of the alkali metal hypophosphite (B) is more preferably 0.03 μm or more and 1000 μm or less, further preferably 0.1 μm or more and 1000 μm or less.

  The average particle size of the alkali metal hypophosphite (B) can be measured by a sieve or a laser diffraction type particle distribution measuring device. Specifically, after obtaining a volume-based particle size distribution of the alkali metal hypophosphite (B) with a laser diffraction particle size distribution analyzer, the arithmetic average diameter (volume average diameter) is defined as the average particle diameter. Can be measured.

  The melting point of the alkali metal hypophosphite (B) is preferably from 50 ° C. to 250 ° C. If the melting point of the alkali metal hypophosphite (B) is 50 ° C. or higher, it is difficult to volatilize, so that it is easy to process or to suppress decomposition of itself. When the melting point of the alkali metal hypophosphite (B) is 300 ° C. or less, the dispersion in the polyester resin (A) becomes good, and the reducing action of the alkali metal hypophosphite (B) is easily developed. It is easy to suppress coloring of the resin. The melting point of the alkali metal hypophosphite (B) can be measured by a differential scanning calorimeter (DSC) as described above.

  As the alkali metal hypophosphite (B), one type may be used alone, or two or more types may be used in combination. The method of adding the alkali metal hypophosphite (B) is not particularly limited, and at least the components (A), (B), (C) and (D) are melt-kneaded as described later. (Dry method), or spraying an aqueous solution containing the component (B) on the surface of a pellet obtained by melt-kneading at least the components (A), (C) and (D). It may be a method (wet method) or a method combining these methods.

  The content of the alkali metal hypophosphite (B) in the polyester resin composition for a reflector according to the present invention may be selected from the group consisting of a polyester resin (A), an alkali metal hypophosphite (B), titanium oxide (C), and inorganic oxide. When the total amount of the filler (D) is 100 parts by mass, the amount is preferably 0.01 part by mass or more and 5 parts by mass or less. When the content of the alkali metal hypophosphite (B) is at least 0.01 part by mass, discoloration due to heat of the molded article (reflecting material) of the polyester resin composition is reduced, and the decrease in reflectance is reduced. Cheap. When the content of the alkali metal hypophosphite (B) is 5 parts by mass or less, the generation of decomposition gas of the alkali metal hypophosphite (B) is not too large, and the workability is not easily impaired. The content of the alkali metal hypophosphite (B) is 100 parts by mass of the total of the polyester resin (A), the alkali metal hypophosphite (B), the titanium oxide (C) and the inorganic filler (D). In this case, the content is more preferably from 0.05 to 1 part by mass, and still more preferably from 0.1 to 0.5 part by mass.

  The content of the alkali metal hypophosphite (B) is preferably from 0.012 parts by mass to 16.7 parts by mass, based on 100 parts by mass of the polyester resin (A), and 0.06 parts by mass. It is more preferable that it is not less than 0.1 part by mass and not more than 6.7 parts by mass, and it is even more preferable that it is 0.12 parts by mass or more and 3.3 parts by mass or less. When the content of the alkali metal hypophosphite (B) is in the above range, discoloration due to heat of the molded article (reflecting material) of the polyester resin composition is reduced, and a decrease in reflectance is easily reduced.

  The phosphorus element concentration (x) derived from the alkali metal hypophosphite (B) in the polyester resin composition for a reflective material of the present invention is the sum of the polyester resin (A) and the alkali metal hypophosphite (B). Is 100 parts by mass, preferably 230 parts by mass or more and 23000 parts by mass or less, more preferably 450 parts by mass or more and 12000 parts by mass or less. When the phosphorus element concentration (x) is within the above range, discoloration due to heat of a molded article (reflecting material) of the polyester resin composition is reduced, and a decrease in reflectance is easily suppressed.

  The phosphorus element concentration may be calculated from the mass ratio of phosphorus atoms contained in the alkali metal hypophosphite (B) and the amount charged, or the fluorescent resin X-ray analysis (XRF; X- ray Fluorescence).

1-3. White pigment (C)
The white pigment (C) contained in the polyester resin composition for a reflective material of the present invention may be any one that can whiten the polyester resin composition and improve the light reflection function. However, the white pigment (C) is a compound different from the alkali metal hypophosphite (B). Examples of the white pigment (C) include titanium oxide, zinc oxide, zinc sulfide, lead white, zinc sulfate, barium sulfate, calcium carbonate, alumina oxide, zirconium oxide, silica and the like. One of these white pigments (C) may be used alone, or two or more thereof may be used in combination. Among them, the white pigment (C) preferably has a refractive index of 2.0 or more and 4.0 or less, and titanium oxide is more preferable because the reflectance and the concealing property of the molded article are easily increased.

  Titanium oxide is preferably a rutile type.

  The white pigment (C) may be treated with a silane coupling agent, a titanium coupling agent, or the like. For example, the white pigment (C) may be surface-treated with a silane-based compound including vinyltriethoxysilane, 2-aminopropyltriethoxysilane, and 2-glycidoxypropyltriethoxysilane.

  From the viewpoint of making the reflectance of the polyester resin composition more uniform, it is preferable that the white pigment (C) has a small aspect ratio, that is, a spherical pigment.

  The average particle size of the white pigment (C) is preferably from 0.1 μm to 0.5 μm, and more preferably from 0.15 μm to 0.3 μm. The average particle diameter of the white pigment (C) is distributed by plotting the particle amount (% by mass) in each particle diameter section of the primary particles using an image diffractometer (Luzex IIIU) based on a transmission electron micrograph. A curve is obtained, a cumulative distribution curve is obtained from the obtained distribution curve, and a value when the cumulative degree of the cumulative distribution curve is 50% can be set.

  The content of the white pigment (C) in the polyester resin composition of the present invention is the total of the polyester resin (A), the alkali metal hypophosphite (B), the white pigment (C), and the inorganic filler (D). When the amount is 100 parts by mass, the amount is preferably from 5 parts by mass to 50 parts by mass. When the content of the white pigment (C) is 5 parts by mass or more, the whiteness of the polyester resin composition is easily increased, and the reflectance is easily increased. When the content of the white pigment (C) is 50 parts by mass or less, fluidity and moldability at the time of molding are not easily impaired. The content of the white pigment (C) is 10 parts by weight when the total of the polyester resin (A), the alkali metal hypophosphite (B), the white pigment (C) and the inorganic filler (D) is 100 parts by mass. The content is more preferably from 50 parts by mass to 50 parts by mass, further preferably from 20 parts by mass to 40 parts by mass, and particularly preferably from 25 parts by mass to 36 parts by mass.

1-4. Inorganic filler (D)
The inorganic filler (D) is a filler of an inorganic compound having a spherical, fibrous or plate-like shape. From the viewpoint of further increasing the strength and toughness of the polyester resin composition, the shape of the inorganic filler (D) is preferably fibrous.

  Examples of the fibrous inorganic filler (D) include glass fiber, wollastonite, potassium titanate whisker, calcium carbonate whisker, aluminum borate whisker, magnesium sulfate whisker, sepiolite, zonotolite, zinc oxide whisker, milled fiber and Cut fibers are included. One of these may be used alone, or two or more thereof may be used in combination. Among them, wollastonite, glass fiber, and potassium titanate whisker are preferable, and wollastonite or glass fiber is more preferable because the average fiber diameter is relatively small and the surface smoothness of the molded article (reflective material) is easily increased. . Wollastonite is preferred from the viewpoint of further enhancing the light shielding effect of the polyester resin composition, and glass fiber is preferred from the viewpoint of further enhancing the mechanical strength of the polyester resin composition.

  The average fiber length (l) of the fibrous inorganic filler (D) is usually 5 mm or less, and from the viewpoint of making the fibrous inorganic filler (D) hard to break and facilitating fine dispersion in the resin. And preferably 4 mm or less. The average fiber length (l) of the fibrous inorganic filler (D) is preferably 2 µm or more, more preferably 8 µm or more, from the viewpoint of further increasing the strength of the polyester resin composition.

  The aspect ratio (average fiber length (l) / average fiber diameter (d)) of the fibrous inorganic filler (D) is preferably from 5 to 2,000, more preferably from 30 to 600. The larger the aspect ratio, the higher the strength and rigidity of the polyester resin composition.

The average fiber length (l) and average fiber diameter (d) of the fibrous inorganic filler (D) in the polyester resin composition can be measured by the following method.
1) After dissolving the polyester resin composition in a hexafluoroisopropanol / chloroform solution (0.1 / 0.9% by volume), a filtrate obtained by filtration is collected.
2) Arbitrary 100 fibrous inorganic fillers (D) among the obtained filtrates were observed with a scanning electron microscope (SEM) (magnification: 50 times), and each fiber length and fiber diameter were measured. I do. Then, the average value of the fiber length can be set to the average fiber length (l), and the average value of the fiber diameter can be set to the average fiber diameter (d).

  The content of the inorganic filler (D) in the polyester resin composition for a reflector according to the present invention is as follows: polyester resin (A), alkali metal hypophosphite (B), titanium oxide (C), and inorganic filler (D). ) Is preferably 1 part by mass or more and 50 parts by mass or less, when the total of (1) is 100 parts by mass. When the content of the inorganic filler (D) is 1 part by mass or more, the heat resistance and strength of the polyester resin composition are easily increased, and when the content is 50 parts by mass or less, fluidity during molding of the polyester resin composition and Moldability is not easily impaired. The content of the inorganic filler (D) is defined assuming that the total of the polyester resin (A), the alkali metal hypophosphite (B), the titanium oxide (C) and the inorganic filler (D) is 100 parts by mass. It is more preferably from 5 parts by mass to 40 parts by mass, further preferably from 7 parts by mass to 25 parts by mass, particularly preferably from 10 parts by mass to 15 parts by mass.

1-5. Other Components The polyester resin composition for a reflector according to the present invention may contain components other than the above-mentioned components (A) to (D), for example, organic oxidants, depending on the intended use, as long as the effects of the present invention are not impaired. Inhibitors (phenols, amines, sulfurs, etc.), light stabilizers (benzotriazoles, triazines, benzophenones, hindered amines, ogizanilides, etc.), heat stabilizers (lactone compounds, vitamin Es, hydroquinones, etc.) Copper halides, iodine compounds, etc., other polymers (olefins such as polyolefins, ethylene / propylene copolymers, ethylene / 1-butene copolymers, olefins such as propylene / 1-butene copolymers) Copolymer, polystyrene, polyamide, polycarbonate, polyacetal, polysulfone, polyphenylene Oxides, fluorine resins, silicone resins, LCP, etc.), flame retardants (bromine, chlorine, phosphorus, antimony, inorganic, etc.), fluorescent brighteners, plasticizers, thickeners, antistatic agents, mold release agents And additives such as pigments, nucleating agents, and lubricants. The total content of other components can be 10% by mass or less, preferably 5% by mass or less, based on the total mass of the polyester resin composition for a reflector.

  Above all, the polyester resin composition for a reflector of the present invention contains a phenolic antioxidant (E) from the viewpoint of more highly suppressing discoloration and a decrease in reflectance when exposed to heat or light for a long period of time. Preferably, it further includes.

  The phenolic antioxidant (E) is a compound having a phenol skeleton, preferably a hindered phenol skeleton. The hindered phenol skeleton is a compound in which two ortho positions to a hydroxy group are an alkyl group and at least one of them is a tert-butyl group. The phenolic antioxidant (E) is a hindered phenolic antioxidant having a hindered phenol skeleton from the viewpoint of more highly suppressing discoloration and a decrease in reflectance when exposed to heat or light for a long period of time. It is preferred that

  Examples of hindered phenolic antioxidants include 2,6-di-t-butyl-4-hydroxytoluene (BHT), pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl). ) Propionate], octadodecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate and the like. . Examples of commercially available products include IRGANOX 1010, IRGANOX 1076, and IRGANOX 1726 (all manufactured by BASF Japan).

  The melting point of the phenolic antioxidant (E) is not particularly limited, but is preferably 60 ° C. or more from the viewpoint of easily suppressing decomposition of the phenolic antioxidant itself and making it difficult to volatilize.

  The content of the phenolic antioxidant (E) was 100 parts by mass based on the total of the polyester resin (A), the alkali metal hypophosphite (B), the white pigment (C), and the inorganic filler (D). At this time, it is preferably at most 2.5 parts by mass, more preferably at most 1 part by mass.

  The content ratio (B) / (E) of the phenolic antioxidant (E) and the alkali metal hypophosphite (B) was exposed to heat or light for a long time due to the synergistic effect of these. From the viewpoint of more highly suppressing discoloration and a decrease in reflectance at that time, it is preferably 0.1 or more and 4 or less, and more preferably 0.1 or more and less than 2.

  In addition, the polyester resin composition for a reflector of the present invention reduces the discoloration when exposed to heat or light over a long period of time, and from the viewpoint of reducing the decrease in reflectance, an organic phosphorus-based antioxidant is used. It is preferred that it is not substantially contained. The phrase “substantially not contained” means that the content is 0.05% by mass or less, preferably 0% by mass, based on the total mass of the polyester resin composition for a reflector.

1-6. Physical Properties The reflectance of the polyester resin composition for a reflector of the present invention at a wavelength of 540 nm or 620 nm is preferably 90% or more, and more preferably 94% or more. The reflectance can be measured by using a molded article obtained by molding the polyester resin composition for a reflective material of the present invention as a test piece, and measuring the reflectance of the test piece using CM3500d manufactured by Konica Minolta. The thickness of the sample piece may be 0.5 mm.

  The reflectance of the polyester resin composition for a reflective material of the present invention at a wavelength of 540 nm or 620 nm measured after heating at 150 ° C. for 500 hours can be, for example, 90% or more. The method of measuring the reflectance after heating is the same as described above. As described above, it is preferable that the polyester resin composition contains an alkali metal hypophosphite (B) in order to reduce a decrease in reflectance after heating.

2. Method for Producing Polyester Resin Composition for Reflecting Material The polyester resin composition of the present invention comprises at least the components (A), (B), (C) and (D) prepared by a known method, for example, a Henschel mixer. , V blender, ribbon blender, or tumbler blender, or after the above-mentioned mixing, further melt-kneading with a single screw extruder, a multi-screw extruder, a kneader or a Banbury mixer, and granulating or pulverizing after the above-mentioned melt kneading. It can be manufactured by a method.

  The surface of the pellets obtained by granulation or pulverization after the above-mentioned melt-kneading, or at least the surfaces of the pellets obtained by melt-kneading the components (A), (C) and (D) are required. Accordingly, the component (B) may be further attached. The method of attaching the component (B) to the surface of the pellet may be a known method. For example, a method in which a solution in which the component (B) is dissolved in a solvent such as water is sprayed on the surface of the pellet and directly attached. And so on. As a device for adhering the component (B), a known device such as a tumbler, Henschel, Proshare mixer, Nauta mixer, flow jet mixer, and Newmar can be used.

  The melt-kneading is preferably performed at a temperature 5 to 30 ° C. higher than the melting point of the polyester resin (A). A preferred lower limit of the melt-kneading temperature can be 275 ° C, more preferably 295 ° C, and a preferred upper limit can be 360 ° C, more preferably 340 ° C.

3. Reflector The reflector of the present invention is a molded article obtained by molding the polyester resin composition for a reflector of the present invention.

  The molding can be performed by a known molding method. Examples of known molding methods include injection molding, insert molding including hoop molding, melt molding, extrusion molding, inflation molding, blow molding, and the like.

  The reflecting material of the present invention is a molded article having at least a surface that reflects light, and may have any shape depending on the application. For example, the reflecting material of the present invention can be a casing or a housing having at least a surface that reflects light. The surface that reflects light may be a flat surface or a curved surface (including a spherical surface). Specifically, the surface that reflects light may have a shape such as a box shape, a funnel shape, a bowl shape, a parabolic shape, a columnar shape, a conical shape, and a honeycomb shape.

  The reflector of the present invention is used as a reflector of various light sources such as an organic EL and a light emitting diode (LED). Above all, it is preferably used as a reflector of a light emitting diode (LED), and more preferably used as a reflector of a light emitting diode (LED) corresponding to surface mounting.

  An LED package having the reflector of the present invention as a reflector of a light emitting diode (LED) includes a substrate, a housing portion provided on the substrate and having a space for mounting an LED, and mounted in the space. It may have an LED and a sealing member for sealing the LED. Then, a housing portion having a space for mounting the LED can be used as the reflecting material of the present invention. Such an LED package includes: 1) a step of forming a reflection plate on a substrate to obtain a housing portion; 2) a process of disposing an LED in the housing portion and electrically connecting the LED to the substrate; 3). Sealing the LED with a sealant. In the sealing step, the sealing agent is heated at a temperature of 100 to 200 ° C. and thermally cured. Furthermore, in the reflow soldering process when mounting the LED package on a printed circuit board, the LED package is exposed to a high temperature of 250 ° C. or more.

  The reflector obtained from the polyester resin composition for a reflector of the present invention contains an alkali metal hypophosphite (B). Thereby, even if it is exposed to high-temperature heat in the above-mentioned sealing step or reflow soldering step, or receives heat or light generated from an LED for a long time in the use environment, there is little discoloration and little decrease in reflectance. . Therefore, a high reflectance can be maintained over a long period of time.

  Such an LED package can be used, for example, for electric and electronic components, indoor lighting, outdoor lighting, automobile lighting, and the like.

  Hereinafter, the present invention will be described with reference to examples. The examples are not to be construed as limiting the scope of the present invention.

1. Preparation of material <Polyester resin (A)>
(Synthesis of polyester resin (A-1))
106.2 parts by mass of dimethyl terephthalate and 94.6 parts by mass of 1,4-cyclohexanedimethanol (cis / trans ratio: 30/70) (manufactured by Tokyo Chemical Industry Co., Ltd.) were mixed. 0.0037 parts by mass of tetrabutyl titanate was added to the mixture, and the mixture was heated from 150 ° C. to 300 ° C. over 3 hours and 30 minutes to cause a transesterification reaction.
At the end of the transesterification reaction, 0.066 parts by mass of magnesium acetate tetrahydrate dissolved in 1,4-cyclohexanedimethanol was added, followed by introduction of 0.1027 parts by mass of tetrabutyl titanate to carry out a polycondensation reaction. . In the polycondensation reaction, the pressure was gradually reduced from normal pressure to 1 Torr over 85 minutes, and the temperature was simultaneously raised to a predetermined polymerization temperature of 300 ° C. Stirring was continued while maintaining the temperature and pressure, and the reaction was terminated when a predetermined stirring torque was reached. Thereafter, the obtained polymer was taken out and subjected to solid-state polymerization at 260 ° C. and 1 Torr or less for 3 hours to obtain a polyester resin (A-1).

  The intrinsic viscosity [η] of the obtained polyester resin (A-1) was 0.6 dl / g, and the melting point was 290 ° C. The intrinsic viscosity [η] and the melting point were measured by the following methods.

(Intrinsic viscosity)
The obtained polyester resin (A-1) was dissolved in a mixed solvent of phenol and tetrachloroethane at 50/50% by mass to prepare a sample solution. The flowing seconds of the obtained sample solution was measured using an Ubbelohde viscometer at 25 ° C. ± 0.05 ° C., and the intrinsic viscosity [η] was calculated by applying the following equation.
[Η] = ηSP / [C (1 + kηSP)]
[Η]: Intrinsic viscosity (dl / g)
ηSP: specific viscosity C: sample concentration (g / dl)
t: Number of seconds during which the sample solution flows down (seconds)
t0: Number of seconds during which the solvent flows down (seconds)
k: constant (gradient obtained by measuring the specific viscosities of samples (three or more points) having different solution concentrations, plotting the solution concentration on the horizontal axis and plotting ηsp / C on the vertical axis)
ηSP = (t−t0) / t0

(Melting point (Tm))
The melting point (Tm) was measured by a differential scanning calorimeter (DSC) according to JIS-K7121. Specifically, a pan for DSC measurement in which a sample was sealed was set in X-DSC7000 (manufactured by SII), and the temperature was raised to 320 ° C. at a rate of 10 ° C./min in a nitrogen atmosphere. After holding for 10 minutes, the temperature was lowered to 30 ° C. by measuring the temperature at 10 ° C./min. The temperature at the peak top of the endothermic peak at the time of temperature rise was defined as “melting point”.

<Phosphorus compound>
(Alkali metal hypophosphite (B))
Alkali metal hypophosphite (B-1): sodium hypophosphite (manufactured by Daido Pharmaceutical Co., Ltd., molecular weight 105.99, average particle diameter 1000 μm, melting point 90 ° C.)
The average particle size of the alkali metal hypophosphite (B) was measured by the following method.

(Average particle size)
After obtaining a volume-based particle size distribution using a laser diffraction type particle size distribution meter (SALD-2100 manufactured by Shimadzu Corporation), the arithmetic average diameter (volume average diameter) was defined as the average particle diameter. The volume-based particle size distribution was obtained from the logarithm of the particle size obtained by analyzing the result of laser diffraction according to Mie's theory.

(Other phosphorus compounds)
Phosphorus compound (b-1): PEP-36 (Antioxidant, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-diphosphite (manufactured by ADEKA Corporation, molecular weight 633, melting point) 234 to 240 ° C)
Phosphorus compound (b-2): sodium pyrophosphate (manufactured by Taiyo Chemical Co., Ltd., molecular weight 265.9, melting point 79 ° C.)
Phosphorus compound (b-3): sodium dihydrogen phosphate (manufactured by Taiyo Chemical Co., Ltd., molecular weight 120.0, melting point 60 ° C.)
Alkaline earth metal hypophosphite (b-4): calcium hypophosphite (manufactured by Daido Pharmaceutical Co., Ltd., molecular weight 170.05, average particle diameter 1000 μm)

<White pigment (C)>
Titanium oxide: powder, average particle size 0.21 μm
The average particle size of the titanium oxide was measured as follows.

(Average particle size)
First, based on a transmission electron microscope photograph, the distribution curve was obtained by plotting the particle amount (% by mass) of each primary particle in each particle diameter section using an image diffractometer (Luzex IIIU). A cumulative distribution curve was obtained from the obtained distribution curve, and a value at a cumulative degree of 50% in the cumulative distribution curve was defined as an average particle size.

<Inorganic filler (D)>
Glass fiber: average fiber length (l) 3 mm, average fiber diameter (R) 6.5 μm, aspect ratio (l / R) 462 (ECS03T-171DE / P9W manufactured by NEC Corporation, treated with silane compound)
The average fiber length (l) and average fiber diameter (R) of the glass fibers were measured as follows.

(Average fiber length, average fiber diameter)
That is, the fiber length and fiber diameter of arbitrary 100 fibers of the inorganic filler (D) were measured at a magnification of 50 times using a scanning electron microscope (SEM). The average value of the obtained fiber lengths was defined as the average fiber length, and the average value of the obtained fiber diameters was defined as the average fiber diameter. The aspect ratio was defined as average fiber length / average fiber diameter.

<Phenolic antioxidant (E)>
Irganox 1010 (antioxidant): tetrakis [3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionic acid] pentaerythritol (manufactured by BASF, melting point 110 to 125 ° C.)

2. Preparation and evaluation of polyester resin composition <Examples 1 and 2 and Comparative Examples 1 to 6>
At a composition ratio shown in Table 1, a polyester resin (A), an alkali metal hypophosphite (B) or another phosphorus compound, a white pigment (C) and an inorganic filler (D) are mixed by a tumbler blender. did. The obtained mixture was melt-kneaded at a cylinder temperature of 300 ° C. with a twin-screw extruder (TEX30α manufactured by Nippon Steel Works) and extruded into strands. After the extrudate was cooled in a water bath, the strand was taken out with a pelletizer and cut to obtain a pellet-shaped polyester resin composition.

  The reflection properties (initial, after heating) of the obtained polyester resin composition were evaluated by the following methods.

<Reflection characteristics>
(Initial reflectance)
The obtained polyester resin composition was injection-molded using the following molding machine under the following molding conditions to prepare a test piece having a length of 30 mm, a width of 30 mm and a thickness of 0.5 mm.
Molding machine: manufactured by Sumitomo Heavy Industries, Ltd., SE50DU
Cylinder temperature: Melting point (Tm) of polyester resin (A) + 10 ° C
Mold temperature: 150 ° C
The reflectance of the obtained test piece in a wavelength region of 360 nm to 740 nm was determined using Minolta CM3500d. The reflectance at a wavelength of 540 nm was used as a representative value, and was used as the initial reflectance.

(Reflectance after heating)
The test piece whose initial reflectance was measured was left in an oven at 170 ° C. for 2 hours. Then, the reflectance of the obtained sample piece was measured by the same method as the initial reflectance, and was defined as the reflectance after heating.

(Reflectance after reflow test)
The sample piece whose initial reflectance was measured was left in an oven at 170 ° C. for 2 hours. Then, the sample piece was heat-treated using an air reflow soldering device (AIS-20-82-C manufactured by Atec Techtron Co., Ltd.) with a temperature profile in which the surface temperature of the sample piece was 260 ° C. and held for 20 seconds ( Heat treatment similar to the reflow soldering process). After the sample piece was gradually cooled, the reflectance was measured in the same manner as the initial reflectance, and the reflectance was taken as the reflectance after the reflow test.

(Reflectance after heating for 500 hours)
The test piece whose initial reflectance was measured was left in an oven at 150 ° C. for 500 hours. Then, the reflectance of the obtained sample piece was measured in the same manner as the initial reflectance, and was set as the reflectance after heating for 500 hours.

(Reflectance after UV light irradiation)
The test piece whose initial reflectance was measured was left for 500 hours in the following ultraviolet irradiation device. Then, the reflectance of the obtained sample piece was measured by the same method as the initial reflectance, and was defined as the reflectance after ultraviolet irradiation.
Ultraviolet irradiation device: Daipla Wintes Co., Ltd. Super Win Mini Output: 16 mW / cm ²

  Table 1 shows the compositions and evaluation results of the polyester resin compositions of Examples 1 and 2 and Comparative Examples 1 to 6.

  As shown in Table 1, in the polyester resin compositions of Examples 1 and 2 containing the alkali metal hypophosphite (B), the reflectance after heating was almost the same as the initial reflectance, or It turns out that it becomes rather high. Further, the amount of change (change amount) in the reflectance after heating at 150 ° C. for a long time is less than 3% at the wavelength of 540 nm and less than 1% at the wavelength of 620 nm, which indicates that the decrease in the reflectance after heating is small. This is considered to be because the discoloration of the polyester resin composition due to heating is small. In addition, in the polyester resin composition of Example 2, the decrease in reflectance after UV light irradiation (＠ wavelength 540 nm) is less than 0.5%, and it can be seen that the decrease in reflectance after light irradiation is small.

  In particular, it can be seen that increasing the content of the alkali metal hypophosphite (B) can further reduce the decrease in reflectance after heating (comparing Examples 1 and 2).

  On the other hand, in the polyester resin compositions of Comparative Examples 1 to 6 containing other phosphorus-based compounds, the reflectance after heating (particularly, the reflectance after heating at 540 nm) is lower than the initial reflectance. I understand. In the polyester resin compositions of Comparative Examples 1 and 3 to 6, the decrease (change) in reflectance after heating at 150 ° C. for a long time was 3% or more at a wavelength of 540 nm and 1% or more at a wavelength of 620 nm. It can be seen that the decrease in reflectance after heating is still large. In addition, in the polyester resin compositions of Comparative Examples 3 and 4, the decrease in reflectance after UV light irradiation (＠ wavelength 540 nm) is 1.3% or more, and it can be seen that the decrease in reflectance after light irradiation is also large. . It is considered that the polyester resin composition of Comparative Example 1 containing the phosphorus compound (b-1), which is an organic phosphorus compound, was because the organic phosphorus compound itself was colored. The polyester resin compositions of Comparative Examples 3 to 6 containing the phosphorus-based compound (b-2) or (b-3), which is an inorganic phosphorus-based compound, do not have a sufficient reducing action (have a sufficient antioxidant function). This is considered to be due to coloring.

  According to the present invention, the discoloration and the decrease in reflectance due to the short-term heat treatment are extremely small, and the discoloration is small even when exposed to heat or light for a long period of time, and the reflection can provide a reflective material with a small decrease in reflectance. A polyester resin composition for materials can be provided.

Claims (10)

A polyester resin (A) having a melting point (Tm) or a glass transition temperature (Tg) of at least 270 ° C. measured by a differential scanning calorimeter (DSC) of at least 30 parts by mass and at most 80 parts by mass;
0.01 to 5 parts by mass of an alkali metal hypophosphite (B),
5 to 50 parts by mass of white pigment (C),
1 to 50 parts by mass of the inorganic filler (D),
(Where the total of (A), (B), (C) and (D) is 100 parts by mass),
Polyester resin composition for reflector. The alkali metal hypophosphite (B) is sodium hypophosphite.
The polyester resin composition for a reflector according to claim 1. The content of the alkali metal hypophosphite (B) is 0.12 parts by mass or more and 3.3 parts by mass or less when the polyester resin (A) is 100 parts by mass.
The polyester resin composition for a reflector according to claim 1. The polyester resin (A) includes a component unit (a1) derived from a dicarboxylic acid and a component unit (a2) derived from a dialcohol,
The component unit (a1) derived from the dicarboxylic acid has a component unit derived from terephthalic acid of 30 mol% or more and 100 mol% or less based on 100 mol% of the total of the component units (a1) derived from the dicarboxylic acid. A component unit derived from an aromatic dicarboxylic acid other than terephthalic acid from 0 mol% to 70 mol%,
The component unit (a2) derived from the dialcohol includes at least one of a component unit derived from an alicyclic dialcohol having 4 to 20 carbon atoms and a component unit derived from an aliphatic dialcohol,
The polyester resin composition for a reflective material according to claim 1. The component unit (a2) derived from the dialcohol includes a component unit derived from an alicyclic dialcohol having a cyclohexane skeleton.
The polyester resin composition for a reflector according to claim 4. The component unit (a2) derived from the dialcohol has a component unit derived from 1,4-cyclohexanedimethanol of 30 mol% or more based on a total of 100 mol% of the component unit (a2) derived from the dialcohol. 100 mol% or less, and containing 0 mol% or more and 70 mol% or less of component units derived from the aliphatic dialcohol.
The polyester resin composition for a reflector according to claim 4. The inorganic filler (D) is a glass fiber,
The polyester resin composition for a reflector according to any one of claims 1 to 6. A phenolic antioxidant (E),
The content ratio (B) / (E) of the alkali metal hypophosphite (B) and the phenolic antioxidant (E) is 0.1 or more and less than 2.
The polyester resin composition for a reflector according to any one of claims 1 to 7. Including the polyester resin composition for a reflective material according to any one of claims 1 to 8,
Reflective material. A reflector for a light emitting diode element,
The reflector according to claim 9.