A polyamide molding composition and its preparation method and application

Abstract

The present invention belongs to the field of polymer technology, and specifically relates to a polyamide molding composition, a preparation method thereof and an application thereof. The polyamide molding composition comprises the following components in parts by weight: 40-75 parts of PAXC / YC resin, 15-45 parts of white pigment, 5-20 parts of reinforcing filler, and 0.5-5 parts of anti-yellowing aid; the terminal amino content [n] of the PAXC / YC resin satisfies the following range: 10mol / t≤[n]≤100mol / t; the anti-yellowing aid comprises at least one of magnesium titanate and magnesium phosphate. The polyamide molding composition prepared by the present invention can effectively inhibit the yellowing of the resin during high-temperature baking, and significantly improve the reflectivity of 450nm wavelength blue light in the LED packaging process.

Description

Technical Field

[0001] The invention belongs to the technical field of polymers, and in particular relates to a polyamide molding composition and a preparation method and application thereof. Background Art

[0002] LED light sources are mainly composed of semiconductor chips, LED light source reflective brackets, gold wires, and packaging glue. The LED light source reflective bracket is the "skeleton" of the LED light source and is also a functional part. The LED packaging process requires solid crystal, wire bonding, and packaging glue curing, and other materials and components are integrated here. The LED reflective bracket needs to reflect the light emitted by the LED chip at a certain angle to reduce light loss, and then pass it through packaging materials such as epoxy resin or silicone to form a light source for LED lighting or display. The LED reflective bracket material is a core material for LED lighting, which is directly related to the performance and life of the LED light source.

[0003] In the field of lighting sources and backlight applications, in order to reduce the number of lamp beads used and achieve energy-saving and environmental protection effects, the brightness of a single lamp bead light source is a very important indicator. The brightness of a single lamp bead light source is related to the chip power and the reflectivity of the LED light source bracket: the greater the chip power, the higher the brightness of a single LED lamp bead, but the higher the melting point requirement for the LED light source bracket; at the same time, the higher the reflectivity of the LED light source bracket, the higher the brightness of a single lamp bead light source. In the prior art, ultra-high content (more than 65wt%) of titanium dioxide is added to increase the surface whiteness to improve the light reflectivity, but this will lead to a decrease in processing performance and easily cause the surface of the LED light source bracket to be uneven, which will reduce the light reflectivity and increase the difficulty of processing. The traditional LED light source bracket material is mainly a combination of semi-aromatic high-temperature resistant polyamide material, reinforced filler, and white pigment. However, the semi-aromatic polyamide material contains unsaturated bonds of the benzene ring. It is affected by shear and heat during processing. Under high-power LED light source conditions, it is easy to yellow, affecting the brightness of the material. In addition, in the material system filled with high white pigment, the dispersibility of the white pigment will also affect the brightness of the material. In addition, the LED packaging process needs to go through SMT, and the SMT process temperature range is between 230-265℃. The LED light source bracket is prone to yellowing when undergoing high-temperature SMT, so the yellowing resistance of the LED light source bracket material directly affects the brightness and reliability of the lamp beads.

[0004] Chinese patent CN102482492A discloses a reflector for LED, wherein a polyamide containing 80-100 mol% of dicarboxylic acid units of 1,4-cyclohexanedicarboxylic acid units and 50-100 mol% of diamine units of aliphatic diamine units having 4-18 carbon atoms is disclosed, and the illumination of the LED reflector at a wavelength of 300-400 nm is 10 mW / cm 2Position, at 120°C, in air, after being irradiated for 336 hours with light from a metal halide lamp through a color filter that transmits light of 295nm-780nm, the reflectivity of the reflector to light of a wavelength of 460nm is more than 90%. However, the patent ignores the packaging process that the LED reflector bracket needs to undergo dehumidification at 180°C for 4 hours, high-temperature baking at 170°C for 2-4 hours for the solid chip, and high-temperature baking at 150-170°C for 4-6 hours for the curing of the encapsulation glue. The final LED reflector has poor yellowing resistance. If the LED light source bracket material has poor yellowing resistance, it will affect the initial brightness of the lamp beads and the reliability during long-term use. Therefore, the present invention focuses on the improvement and improvement of the yellowing resistance of the LED light source bracket material. Summary of the invention

[0005] The present invention aims to provide a polyamide molding composition and a preparation method and application thereof. The polyamide molding composition prepared by the present invention can effectively inhibit the yellowing of resin during high-temperature baking, and significantly improve the reflectivity of the light source bracket material to 450nm wavelength blue light after undergoing the LED packaging process.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme: a polyamide molding composition, comprising the following components in parts by weight: 40-75 parts of PAXC / YC resin, 15-45 parts of white pigment, 5-20 parts of reinforcing filler, and 0.5-5 parts of anti-yellowing additive;

[0007] The PAXC / YC resin has an XC unit content of 60-100 mol% and a YC unit content of 0-40 mol% based on the molar percentage of PAXC / YC; wherein the XC unit is composed of 1,4-cyclohexanedicarboxylic acid and a diamine unit X, and the diamine unit X is selected from at least one of a 1,9-nonanediamine unit, a 1,10-decanediamine unit, and a 1,12-dodecanediamine unit; and the YC unit is composed of 1,4-cyclohexanedicarboxylic acid and a diamine unit Y, and the diamine unit Y is selected from at least one of aliphatic diamine units having 5 to 13 carbon atoms;

[0008] The terminal amino group content [n] of the PAXC / YC resin satisfies the following range: 10 mol / t≤[n]≤100 mol / t; the terminal amino group content [n] of the PAXC / YC resin is obtained by measuring with an automatic potentiometric titrator;

[0009] The anti-yellowing additive includes at least one of magnesium titanate and magnesium phosphate.

[0010] Preferably, the polyamide molding composition comprises the following components in parts by weight: 60-65 parts of PAXC / YC resin, 30-40 parts of white pigment, 10-15 parts of reinforcing filler, and 1-4 parts of anti-yellowing additive.

[0011] Preferably, the white pigment includes at least one of titanium dioxide and zinc sulfide.

[0012] Preferably, the terminal amino group content [n] of the PAXC / YC resin satisfies the following range: 20 mol / t≤[n]≤70 mol / t.

[0013] Preferably, the reinforcing filler includes at least one of glass fiber, wollastonite, potassium titanate and calcium sulfate.

[0014] Preferably, the average particle size D90 of the anti-yellowing aid is 0.5-8 μm.

[0015] More preferably, the average particle size D90 of the anti-yellowing aid is 1-6 μm.

[0016] Preferably, the average particle size D90 of the white pigment is 0.05-0.6 μm.

[0017] More preferably, the average particle size D90 of the white pigment is 0.1-0.5 μm.

[0018] The average particle size D90 of the anti-yellowing additive and the white pigment of the present invention is obtained by dispersing the filler in an ethanol solution and testing with a Malvern particle size distribution instrument.

[0019] Preferably, when the white pigment is selected from titanium dioxide, the anti-yellowing aid is selected from magnesium titanate; when the white pigment is selected from zinc sulfide, the anti-yellowing aid is selected from magnesium phosphate.

[0020] Preferably, the mass ratio of the titanium dioxide to magnesium titanate is (15-45):(0.5-5); the mass ratio of the zinc sulfate to magnesium phosphate is (15-45):(0.5-5).

[0021] Preferably, the mass ratio of the white pigment to the anti-yellowing additive is (10-40):1.

[0022] Preferably, the aliphatic diamine having 5 to 13 carbon atoms in the PAXC / YC resin is at least one selected from 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and 1,13-tridecanediamine.

[0023] Preferably, the PAXC / YC resin has an XC unit content of 65-90 mol % and a YC unit content of 10-35 mol %, based on the PAXC / YC molar percentage.

[0024] More preferably, the PAXC / YC resin has an XC unit content of 70-79.99 mol % and a YC unit content of 20.01-30 mol % based on the PAXC / YC molar percentage.

[0025] Preferably, the melting point of the PAXC / YC resin is greater than 320°C.

[0026] The polymerization method of PAXC / YC resin is as follows: Prepolymerization: Put polymerization monomers (diacid, diamine), end-capping agent benzoic acid and deionized water into a stainless steel high-pressure reactor equipped with mechanical stirring. After vacuuming and replacing with N2 three times, start heating and stirring, and heat to 170-190℃ at a rate of 4-6℃ / min. After constant temperature for 1-2 hours, heat to 260-280℃ at a rate of 1-3℃ / min and slowly stir and keep constant temperature for 3-5h to allow the prepolymerization reaction to proceed fully. After the constant temperature is over, slowly increase the temperature to 270-290℃ and start draining to normal pressure. When the pressure drops to normal pressure, close the drain valve, the reaction is over, and the material is discharged at room temperature. Solid phase viscosity enhancement: Put the material prepared in the prepolymerization process into a vacuum drum, the drum speed is set to 10-15r / min, and the vacuum degree is set to 25-35Pa. Raise the temperature at a rate of 15-25°C / min. When the temperature reaches 260-270°C, take a sample to test the viscosity. Determine the discharging end point based on the viscosity result.

[0027] Preferably, the polyamide molding composition has a reflectivity of >90% for blue light with a wavelength of 450 nm.

[0028] The present invention also claims a method for preparing the polyamide molding composition, comprising the following steps:

[0029] The various components are mixed, extruded and pelletized to prepare the polyamide molding composition.

[0030] Preferably, the temperature of the extrusion granulation is 280-330°C and the rotation speed is 400-500r / min.

[0031] The present invention also claims to protect the use of the polyamide molding composition in preparing LED reflective materials. The LED reflective materials include LED reflective brackets and the like.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention selects PAXC / YC resins with higher melting points, better yellowing resistance and the ability to withstand higher power light sources, and controls the terminal amino group content of the PAXC / YC resins during the polymerization process to make the resins have excellent yellowing resistance. At the same time, the resins can effectively inhibit the yellowing of the resins during high-temperature baking through the interaction between the resins and components such as anti-yellowing aids with specific contents, and significantly improve the reflectivity of 450nm wavelength blue light of the polyamide molding composition after the LED packaging process (indicating that the LED reflective bracket can achieve a higher light source reflectivity), thereby solving the problem of severe yellowing of the PAXC / YC resins during the LED packaging process and high-temperature lighting aging. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] In the following examples and comparative examples, the experimental methods used are conventional methods unless otherwise specified.

[0036] The raw materials used in the examples and comparative examples are shown in Table 1.

[0037] Table 1

[0038]

[0039]

[0040]

[0041]

[0042]

[0043] Examples 1 to 28 and Comparative Examples 1 to 5

[0044] The components and weight proportions of the polyamide molding compositions of Examples 1 to 28 and Comparative Examples 1 to 5 are shown in Tables 2 to 4.

[0045] The preparation method of the polyamide molding composition of Examples 1 to 28 and Comparative Examples 1 to 5 comprises the following steps:

[0046] The components are added into a mixer and mixed evenly, and then extruded and granulated by a twin-screw extruder to obtain a polyamide molding composition; wherein the screw temperature range is 280-330°C and the rotation speed is 400-500r / min.

[0047] Table 2 Component dosage in the examples (parts by weight)

[0048]

[0049]

[0050] Table 3 Component dosage in the examples (parts by weight)

[0051]

[0052]

[0053] Table 4 Component dosage in comparative example (parts by weight)

[0054]

[0055] Performance Testing

[0056] The polyamide molding compositions prepared in the examples and comparative examples were tested for their yellowing resistance.

[0057] Yellowing resistance: Characterized by the reflectivity difference ΔR of the blue light source (450nm) before and after SMT. A test piece with a length of 60mm, a width of 60mm and a thickness of 1mm was prepared by injection molding the polyamide molding composition. The reflectivity R1 of the test piece to 450nm wavelength light was measured using a Color Eye 7000A colorimeter, and then the test piece was baked in an SMT reflow soldering device once, and the reflectivity R2 of the test piece to 460nm wavelength light was tested. ΔR = R1-R2, and the smaller the ΔR value, the better the yellowing resistance of the composition.

[0058] The test results are shown in Table 5.

[0059] Table 5

[0060]

[0061]

[0062]

[0063] It can be seen from the experimental data in Table 5 that the emissivity of the polyamide molding composition prepared in the embodiment of the present invention at a wavelength of 450nm blue light is greater than 90%, which can be achieved in the range of 92.02 to 95.17%. At the same time, after packaging treatment, the emissivity of the blue light at a wavelength of 450nm is greater than 89.23%, which can be maintained in the range of 89.23 to 93.57%. The reflectivity change rate of the polyamide molding composition changes less and can be maintained in the range of 1.6 to 3.82.

[0064] In Comparative Example 1, the type of resin component selected is not appropriate, and in Comparative Example 2, no anti-yellowing additive is added. The initial reflectivity of the obtained polyamide molding composition at 450nm wavelength blue light is reduced, and the reflectivity after the packaging process is significantly reduced, and the degree of change in the reflectivity change rate is large; in Comparative Example 3, the type of anti-yellowing additive selected is not appropriate, resulting in the reflectivity of the final polyamide molding composition at 450nm wavelength blue light and the reflectivity after the packaging process being significantly worse than those in the embodiment, and the reflectivity retention rate is worse than that without adding the anti-yellowing additive; the terminal amino group content of the PAXC / YC resin selected in Comparative Examples 4-5 is not appropriate, resulting in the yellowing resistance of the final polyamide molding composition being significantly worse than that in the embodiment.

[0065] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A polyamide molding composition, characterized in that The composition comprises the following components in parts by weight: 40-75 parts of PAXC / YC resin, 15-45 parts of white pigment, 5-20 parts of reinforcing filler, and 0.5-5 parts of anti-yellowing additive; The PAXC / YC resin has an XC unit content of 60-100 mol% and a YC unit content of 0-40 mol% based on the molar percentage of PAXC / YC; wherein the XC unit is composed of 1,4-cyclohexanedicarboxylic acid and a diamine unit X, and the diamine unit X is selected from at least one of a 1,9-nonanediamine unit, a 1,10-decanediamine unit, and a 1,12-dodecanediamine unit; and the YC unit is composed of 1,4-cyclohexanedicarboxylic acid and a diamine unit Y, and the diamine unit Y is selected from at least one of aliphatic diamine units having 5 to 13 carbon atoms; The terminal amino group content [n] of the PAXC / YC resin satisfies the following range: 10 mol / t≤[n]≤100 mol / t; The anti-yellowing additive includes at least one of magnesium titanate and magnesium phosphate.

2. The polyamide molding composition according to claim 1, characterized in that The invention comprises the following components in parts by weight: 60-65 parts of PAXC / YC resin, 30-40 parts of white pigment, 10-15 parts of reinforcing filler and 1-4 parts of anti-yellowing additive.

3. The polyamide molding composition according to claim 1, characterized in that At least one of the following (1) to (3): (1) The white pigment comprises at least one of titanium dioxide and zinc sulfide; (2) The terminal amino group content [n] of the PAXC / YC resin satisfies the following range: 20 mol / t≤[n]≤70 mol / t; (3) The reinforcing filler includes at least one of glass fiber, wollastonite, potassium titanate, and calcium sulfate.

4. The polyamide molding composition according to claim 1, characterized in that At least one of the following (1) to (2): (1) The average particle size of the anti-yellowing additive is 0.5 to 8 μm; (2) The average particle size of the white pigment is 0.05-0.6 μm.

5. The polyamide molding composition according to claim 3, characterized in that When the white pigment is selected from titanium dioxide, the anti-yellowing aid is selected from magnesium titanate; when the white pigment is selected from zinc sulfide, the anti-yellowing aid is selected from magnesium phosphate.

6. The polyamide molding composition according to claim 1, characterized in that At least one of the following (1) to (3): (1) The aliphatic diamine having 5 to 13 carbon atoms in the PAXC / YC resin is at least one selected from 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and 1,13-tridecanediamine; (2) the PAXC / YC resin has an XC unit content of 65-90 mol % based on the molar percentage of PAXC / YC; (3) The melting point of the PAXC / YC resin is greater than 320°C.

7. The polyamide molding composition according to claim 1, characterized in that The polyamide molding composition has a reflectivity of more than 90% to blue light with a wavelength of 450 nm.

8. A method for preparing a polyamide molding composition as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: The various components are mixed, extruded and pelletized to prepare the polyamide molding composition.

9. The preparation method according to claim 8, characterized in that: The temperature of the extrusion granulation is 280-330° C. and the rotation speed is 400-500 r / min.

10. Use of the polyamide molding composition according to any one of claims 1 to 7 in the preparation of LED reflective materials.

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