High-temperature-resistant and anti-yellowing LED packaging glue

Abstract

The invention discloses high-temperature-resistant and anti-yellowing LED (light-emitting diode) packaging glue which comprises glue A, glue B and powder C, the adhesive A comprises epoxy resin, a flexibilizer, a flatting agent, a main antioxidant, an auxiliary antioxidant, a diluent, a defoaming agent and a silane coupling agent; wherein the main antioxidant is a hindered phenol antioxidant; the auxiliary antioxidant is a phosphite ester antioxidant; the glue B comprises an anhydride curing agent and an accelerant; and the powder C comprises diffusion powder and matte powder. The hindered phenol antioxidant and the phosphite antioxidant have a synergistic effect, and the phosphite antioxidant reduces an oxidation product of the hindered phenol antioxidant, namely a benzoquinone chromophoric group, so that the color of a system is protected, and the long-term stability of the material is ensured; the heat resistance, the aging resistance, the oxidation resistance and the UV resistance of the packaging glue are improved, so that the packaging glue does not generate color change, the color of a system is protected, the long-term stability of a material is ensured, the yellowing delaying rate reaches 50% or above, and the high temperature resistance can reach 260 DEG C.

Description

Technical Field

[0001] The invention relates to the technical field of LED packaging, and in particular to a high temperature resistant and yellowing resistant LED packaging glue. Background Art

[0002] The structure of outdoor LED lamp beads is generally composed of brackets, chips, packaging glue, and wires, among which the packaging glue is mainly composed of epoxy resin and filler. Affected by the high-temperature curing of LED lamp bead solder paste, higher requirements are placed on the heat resistance of the packaging glue. Secondly, for outdoor use environments, in some places with high temperatures all year round, the LED packaging glue needs to have better high-temperature resistance and anti-yellowing effects, so that the product module color cast problem can be solved and the light decay will be reduced accordingly.

[0003] The existing LED packaging technology mainly uses a one-time dispensing packaging method using a packaging glue containing fillers, because the packaging glue with fillers can effectively improve the matte problem of lamp beads and soften the light source. However, the use environment of outdoor LED lamp beads is relatively harsh. Due to the energy impact of high outdoor temperatures, the packaging glue is prone to yellowing; and the packaging glue must also undergo long-term high-temperature baking during the curing process; at the same time, the LED display screen must also undergo a high-temperature baking process during the production process. Therefore, LED packaging glue has a greater problem of yellowing due to heat, which in turn causes the problem of uneven yellowing of outdoor LED modules, and also causes a significant attenuation of light intensity. Therefore, the development of a high-temperature and yellowing-resistant LED packaging glue formula can greatly improve the heat resistance of LED packaging glue, making it less likely to yellow and reduce light decay. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a high-temperature resistant and yellowing resistant LED packaging glue. A hindered phenol antioxidant and a phosphite antioxidant are added to glue A. The two antioxidants work synergistically to improve the heat resistance, aging resistance, oxidation resistance and UV resistance of the packaging glue, prevent discoloration, protect the color of the system, and ensure the long-term stability of the material.

[0005] In order to solve the above technical problems, the present invention provides a high temperature resistant and yellowing resistant LED packaging glue, which is measured by weight.

[0006] The packaging glue comprises 80-120 parts of A glue, 80-120 parts of B glue and 5-35 parts of C powder;

[0007] The A glue comprises 70-110 parts of epoxy resin, 1-10 parts of toughening agent, 0.1-1 parts of leveling agent, 0.1-1 parts of primary antioxidant, 0.05-0.5 parts of secondary antioxidant, 10-30 parts of diluent, 0.1-1 parts of defoaming agent, and 0.01-1 parts of silane coupling agent;

[0008] The main antioxidant is a hindered phenol antioxidant with a melting point of 159-163°C; the auxiliary antioxidant is a phosphite antioxidant with a melting point of 220-230°C;

[0009] The B glue comprises 80-120 parts of anhydride curing agent and 0.01-2 parts of accelerator;

[0010] The C powder includes 1-5 parts of diffusion powder and 10-30 parts of matte powder.

[0011] The present invention adds a main antioxidant, a hindered phenol antioxidant, and a secondary antioxidant, a phosphite antioxidant, to the A glue, and the two work synergistically. Among them, the hindered phenol antioxidant captures peroxide free radicals, terminates the free radical chain transfer and growth in the oxidation process, thereby preventing the aging of the polymer material; the phosphite antioxidant mainly decomposes the peroxide (ROOH / ROOR) generated during the thermal aging of the polymer to form a stable alcohol or ether structure (ROH / ROOR), further enhancing the antioxidant effect. During use, the hindered phenol antioxidant and the phosphite antioxidant are used in combination, and the phosphite antioxidant reduces the oxidation product of the hindered phenol antioxidant, that is, the benzoquinone chromophore, thereby protecting the color of the system and ensuring the long-term stability of the material.

[0012] Furthermore, the viscosity of the glue is 7000-10000 mPa·s.

[0013] Furthermore, the hindered phenol antioxidant is selected from one or more of monohydric hindered phenol, polyhydric hindered phenol, alkylated monophenol, bisphenol structure antioxidant, semi-hindered phenol antioxidant, and asymmetric hindered phenol antioxidant.

[0014] Furthermore, the phosphite antioxidant is selected from one or more of bisphenol A phosphite, antioxidant 168, antioxidant 6260, and antioxidant S-9228.

[0015] Furthermore, the hindered phenol antioxidant is selected from the compounds of the following structural formula:

[0016]

[0017] This structural compound is a hindered phenol antioxidant with three functional groups, which has higher steric hindrance efficiency, no pollution and no coloring. Due to its high molecular weight and melting point, it has extremely low volatility, low migration, good water extraction resistance, and can give the encapsulation glue excellent thermal oxidation resistance and light oxidation resistance;

[0018] And / or, the phosphite antioxidant is selected from the compounds of the following structural formula:

[0019]

[0020] Furthermore, the epoxy resin is selected from one or more of glycidyl ethers, glycidyl esters, glycidyl amines, aliphatic epoxy resins and epoxidized olefins. Epoxy resin is the main component of packaging glue, plays a sealing role, and achieves a good packaging effect.

[0021] Furthermore, the toughening agent is selected from one or more of polyamide toughening agents, polyether toughening agents, polyester toughening agents, polyimide toughening agents, polyurethane toughening agents, thermoplastic toughening agents, thermosetting toughening agents, active toughening agents and inactive toughening agents. The toughening agent eliminates internal stress and makes the encapsulated colloid have better resistance to cold and heat shock.

[0022] Furthermore, the leveling agent is selected from one or more of silicone leveling agents, acrylate leveling agents and fluorocarbon leveling agents. The leveling agent is used to make the encapsulation glue have better leveling properties and make the surface of the colloid smooth and flat.

[0023] And / or, the defoamer is selected from one or more of silicone oil defoamers, surfactant defoamers, organic defoamers and polymer defoamers. The defoamer is used to eliminate bubbles in the colloid and is not easy to produce cavities.

[0024] Further, the silane coupling agent is selected from one or more of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, vinyl silane coupling agent, bis-[γ-(triethoxysilyl)propyl] tetrasulfide and γ-glycidyloxypropyl trimethoxysilane. The silane coupling agent is used to improve the dispersibility and bonding strength of the epoxy resin and the inorganic filler, and also to enhance the airtightness of the packaging glue.

[0025] Furthermore, the diluent is selected from active diluent and / or inactive diluent. The diluent is used to reduce the viscosity of the resin, so as to achieve better dispensing effect and machine operability.

[0026] Furthermore, the acid anhydride curing agent is selected from one or more of aromatic acid anhydrides, aliphatic acid anhydrides, aliphatic acid anhydrides, halogen-containing acid anhydrides, and low eutectic point acid anhydrides; the acid anhydride curing agent is a substance that plays a chemical role in the ring opening of epoxy resin;

[0027] And / or, the accelerator is selected from one or more of organic amine salts, acetylacetonate metal salts, triphenylphosphine or phosphonium salts, organic carboxylates and halide quaternary ammonium salts; the accelerator is a chemical substance that accelerates the reaction between the anhydride curing agent and the epoxy resin and improves the chemical reaction activity.

[0028] Furthermore, the particle size of the diffusion powder is 1-5 μm and the density is 1-3 g / cm 3; Wherein, the diffusion powder is used to even out the light and make the light emission softer; preferably, the diffusion powder is a silicon dioxide sphere;

[0029] And / or, the matte powder has a particle size of 4-7 μm and a density of 0.1-0.5 g / cm 3 ; Wherein, the matte powder is for matte effect, and the surface does not have a mirror effect; preferably, the matte powder is cotton-like silicon dioxide;

[0030] And / or, the whiteness hue of the diffusion powder and the matte powder is ≥92%.

[0031] Beneficial effects of the present invention:

[0032] The present invention adds hindered phenol antioxidants and phosphite antioxidants to the glue. The hindered phenol antioxidants capture peroxide free radicals and terminate the free radical chain transfer and growth in the oxidation process, thereby preventing the aging of the polymer material; the phosphite antioxidant mainly decomposes the peroxide (ROOH / ROOR) generated in the thermal aging process of the polymer to form a stable alcohol or ether structure (ROH / ROOR), thereby further enhancing the antioxidant effect.

[0033] The hindered phenol antioxidant and the phosphite antioxidant of the present invention work synergistically. The phosphite antioxidant reduces the oxidation product of the hindered phenol antioxidant, namely, the benzoquinone chromophore group, thereby protecting the color of the system and ensuring the long-term stability of the material.

[0034] The encapsulating glue of the invention improves the heat resistance, anti-aging, anti-oxidation and anti-UV performance of the encapsulating glue, prevents discoloration, protects the system color, ensures the long-term stability of the material, delays the yellowing rate by more than 50%, and can withstand high temperatures of up to 260°C. DETAILED DESCRIPTION

[0035] The technical solution of the present invention will be described clearly and completely below in conjunction with the specific 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 creative work are within the scope of protection of the present invention.

[0036] The present embodiment provides a high temperature resistant and yellowing resistant LED packaging glue, which comprises 80-120 parts of A glue, 80-120 parts of B glue and 5-35 parts of C powder by weight; the A glue comprises 70-110 parts of epoxy resin, 1-10 parts of toughening agent, 0.1-1 parts of leveling agent, 0.1-1 parts of primary antioxidant, 0.05-0.5 parts of secondary antioxidant, 10-30 parts of diluent, 0.1-1 parts of defoaming agent, and 0.01-1 parts of silane coupling agent; wherein the primary antioxidant is a hindered phenol antioxidant with a melting point of 159-163°C; the secondary antioxidant is a phosphite antioxidant with a melting point of 220-230°C; the B glue comprises 80-120 parts of anhydride curing agent and 0.01-2 parts of accelerator; the C powder comprises 1-5 parts of diffusion powder and 10-30 parts of matte powder.

[0037] As a specific example, the viscosity of the glue is 7000-10000 mPa·s.

[0038] As a preferred embodiment, the hindered phenol antioxidant is selected from one or more of monohydric hindered phenol, polyhydric hindered phenol, alkylated monophenol, bisphenol structure antioxidant, semi-hindered phenol antioxidant, and asymmetric hindered phenol antioxidant. More preferably, the hindered phenol antioxidant is selected from the following compounds:

[0039]

[0040] As a preferred embodiment, the phosphite antioxidant is selected from one or more of bisphenol A phosphite, antioxidant 168, antioxidant 6260, and antioxidant S-9228. More preferably, the phosphite antioxidant is selected from the compounds of the following structural formula:

[0041]

[0042] As a specific example, the epoxy resin is selected from one or more of glycidyl ethers, glycidyl esters, glycidyl amines, aliphatic epoxy resins and epoxidized olefins. Epoxy resin is the main component of packaging glue, plays a sealing role, and achieves a good packaging effect.

[0043] As a specific example, the toughening agent is selected from one or more of polyamide toughening agents, polyether toughening agents, polyester toughening agents, polyimide toughening agents, polyurethane toughening agents, thermoplastic toughening agents, thermosetting toughening agents, active toughening agents and inactive toughening agents. The toughening agent plays a role in eliminating internal stress, so that the encapsulated colloid has a better resistance to cold and heat shock.

[0044] As a specific example, the leveling agent is selected from one or more of silicone leveling agents, acrylate leveling agents and fluorocarbon leveling agents. The leveling agent is to make the encapsulation glue have better leveling properties and make the colloid surface smooth and flat. The defoamer is selected from one or more of silicone oil defoamers, surfactant defoamers, organic defoamers and polymer defoamers. The defoamer is to eliminate bubbles in the colloid and is not easy to produce voids. The silane coupling agent is selected from one or more of γ-aminopropyl triethoxysilane, γ-aminopropyl trimethoxysilane, vinyl silane coupling agent, bis-[γ-(triethoxysilyl)propyl] tetrasulfide and γ-glycidyl ether oxypropyl trimethoxysilane. On the one hand, the silane coupling agent is to make the epoxy resin and the inorganic filler have better dispersibility and bonding force, and on the other hand, it is also conducive to enhancing the airtightness effect of the encapsulation glue. The diluent is selected from active diluents and / or inactive diluents. The diluent is used to reduce the viscosity of the resin, resulting in better dispensing effect and machine operability.

[0045] As a specific example, the anhydride curing agent is selected from one or more of aromatic anhydrides, aliphatic anhydrides, aliphatic anhydrides, halogen-containing anhydrides, and low eutectic point anhydrides; the anhydride curing agent is a substance that plays a chemical role in the ring opening of epoxy resin; the accelerator is selected from one or more of organic amine salts, acetylacetone metal salts, triphenylphosphine or phosphonium salts, organic carboxylates and halide quaternary ammonium salts; the accelerator is a chemical substance that is used to accelerate the reaction of the anhydride curing agent with the epoxy resin and improve the chemical reaction activity.

[0046] As a specific example, the particle size of the diffusion powder is 1-5 μm, and the density is 1-3 g / cm 3 ; The diffusion powder is used to even out the light and make the light softer; preferably, the diffusion powder is a silicon dioxide sphere; the particle size of the matte powder is 4-7 μm, and the density is 0.1-0.5 g / cm 3 ; Wherein, the matte powder has a mirror-like surface in order to achieve matte effect; preferably, the matte powder is cotton-like silica; the whiteness hue of the diffusion powder and the matte powder is ≥92%.

[0047] The following are specific embodiments.

[0048] Example 1

[0049] This embodiment relates to a high temperature resistant and yellowing resistant LED packaging glue and a preparation method thereof, which comprises, by mass: 100 parts of A glue, 90 parts of B glue and 20 parts of C powder;

[0050] Glue A, by mass, includes 87.15 parts of aliphatic epoxy resin, 0.2 parts of silicone leveling agent, 2 parts of active toughening agent, 0.4 parts of primary antioxidant, 0.1 parts of auxiliary antioxidant, 0.1 parts of organic defoamer, 10 parts of active diluent, and 0.05 parts of γ-aminopropyl triethoxysilane. Glue B, by mass, includes 89.5 parts of aliphatic anhydride curing agent and 0.5 parts of triphenylphosphine accelerator. Powder C, by mass, includes 5 parts of diffusion powder spherical silica and 15 parts of matte powder cotton-like silica.

[0051] Wherein, the primary antioxidant is selected from the compounds of the following structural formula:

[0052]

[0053] The secondary antioxidant is selected from the compounds of the following structural formula:

[0054]

[0055] Glue A, glue B and powder C were mixed evenly by a vacuum stirring and degassing machine to obtain packaging glue with a viscosity of 7500 mPa·s.

[0056] Example 2

[0057] The difference between this embodiment and embodiment 1 is that: the main antioxidant is 0.3 parts, the auxiliary antioxidant is 0.2 parts, and the other components and steps remain unchanged.

[0058] Example 3

[0059] The difference between this embodiment and embodiment 1 is that: 87.05 parts of aliphatic epoxy resin, 0.5 parts of primary antioxidant, 0.1 parts of secondary antioxidant, and other components and steps remain unchanged.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that the primary antioxidant and the secondary antioxidant are replaced by antioxidant 1010, the amount of antioxidant 1010 is 0.5 parts, and the other components and steps remain unchanged.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that no auxiliary antioxidant is added, and the amount of the main antioxidant is adjusted to 0.5 parts, and the other components and steps remain unchanged.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is that no primary antioxidant is added, and the amount of the secondary antioxidant is adjusted to 0.5 parts, and the other components and steps remain unchanged.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 1 is that no primary antioxidant and secondary antioxidant are added, and the amount of aliphatic epoxy resin is adjusted to 87.65 parts, and other components and steps remain unchanged.

[0068] Comparative Example 5

[0069] The difference between this comparative example and Example 1 is that: 85.65 parts of aliphatic epoxy resin, 1.6 parts of primary antioxidant, 0.4 parts of secondary antioxidant, and other components and steps remain unchanged.

[0070] Test Case

[0071] Prepare an aluminum box with a diameter of 5 cm and a height of 4 cm, add the glue mixed in the embodiment and the comparative example into 11 aluminum boxes respectively, the glue thickness is 2 cm, use an oven for heat curing and molding, peel off the aluminum box, and perform 10 reflow oven tests. After each reflow, keep a piece of glue cake, and then use a whiteness meter to test the whiteness value of the glue cake. Among them, the reflow adopts a segmented temperature zone design, 180℃*2min+200℃*2min+240℃*2min+260℃*2min+250℃*2min, and the highest temperature zone temperature is 260℃.

[0072] The whiteness value was determined by using a microcomputer-based desktop whiteness meter from Hangzhou Qiwei Instrument Co., Ltd., model WSB-3C, power supply voltage: 220V. After the machine was turned on, whiteness calibration was first performed. The first step was to place the black tube on the test port for calibration, and the second step was to place the white plate on the test port for calibration. After the calibration was completed, the glue block to be tested was placed on the test port, and the measurement key was pressed to obtain the whiteness value and record it. Generally, the higher the whiteness value, the higher the whiteness of the product, and the smaller the difference, the smaller the color difference of the product. The whiteness values ​​of the glue obtained in Examples 1-3 and Comparative Examples 1-5 were measured at the beginning and after 1-10 reflow soldering, respectively, as shown in Table 1.

[0073] Table 1

[0074]

[0075]

[0076] It can be seen from Table 1 that the glue prepared in Examples 1-3 of the present invention has excellent high temperature resistance, with a high temperature resistance of up to 260°C. It also has excellent anti-yellowing performance, and the whiteness attenuation rate after 10 reflow solderings is low, among which the whiteness attenuation rate of Example 1 is only 6.45%.

[0077] From the comparison between Example 1 and Comparative Example 1, it can be seen that after adding common antioxidant 1010 to the glue, the yellowing degree is more serious after 10 high-temperature reflow soldering, and the whiteness decay rate reaches 41.53%. From the comparison between Example 1 and Comparative Examples 2-3, it can be seen that the heat resistance effect of adding the main antioxidant and the auxiliary antioxidant of the present invention alone is relatively poor, because the main antioxidant and the auxiliary antioxidant work together, and a single component cannot play a synergistic role. The glue compounded with the two antioxidants in Example 1 has a higher whiteness, a slower yellowing degree, and a rate delay of 70.6%.

[0078] From the comparison between Example 1 and Comparative Example 4, it can be seen that the high temperature resistance without adding an antioxidant is poor and the whiteness decay rate is high. At the same time, from the comparison between Example 1 and Comparative Example 5, it can be seen that when the amount of the antioxidant added is not within the range specified by the present invention, the glue components cannot cooperate with each other and the whiteness decay rate is high.

[0079] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A high temperature resistant and yellowing resistant LED packaging glue, characterized in that: By weight, The packaging glue comprises 80-120 parts of A glue, 80-120 parts of B glue and 5-35 parts of C powder; The A glue comprises 70-110 parts of epoxy resin, 1-10 parts of toughening agent, 0.1-1 parts of leveling agent, 0.1-1 parts of primary antioxidant, 0.05-0.5 parts of secondary antioxidant, 10-30 parts of diluent, 0.1-1 parts of defoaming agent, and 0.01-1 parts of silane coupling agent; The main antioxidant is a hindered phenol antioxidant with a melting point of 159-163°C; the auxiliary antioxidant is a phosphite antioxidant with a melting point of 220-230°C; The B glue comprises 80-120 parts of anhydride curing agent and 0.01-2 parts of accelerator; The C powder includes 1-5 parts of diffusion powder and 10-30 parts of matte powder.

2. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The hindered phenol antioxidant is selected from one or more of monohydric hindered phenol, polyhydric hindered phenol, alkylated monophenol, bisphenol structure antioxidant, semi-hindered phenol antioxidant and asymmetric hindered phenol antioxidant.

3. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The phosphite antioxidant is selected from one or more of bisphenol A phosphite, antioxidant 168, antioxidant 6260, and antioxidant S-9228.

4. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The hindered phenol antioxidant is selected from the compounds of the following structural formula: And / or, the phosphite antioxidant is selected from the compounds of the following structural formula:

5. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The epoxy resin is selected from one or more of glycidyl ethers, glycidyl esters, glycidyl amines, aliphatic epoxy resins and epoxidized olefins.

6. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The toughening agent is selected from one or more of polyamide toughening agents, polyether toughening agents, polyester toughening agents, polyimide toughening agents, polyurethane toughening agents, thermoplastic toughening agents, thermosetting toughening agents, active toughening agents and inactive toughening agents.

7. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The leveling agent is selected from one or more of an organic silicon leveling agent, an acrylate leveling agent and a fluorocarbon leveling agent; And / or, the defoaming agent is selected from one or more of silicone oil defoaming agents, surfactant defoaming agents, organic defoaming agents and polymer defoaming agents.

8. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The silane coupling agent is selected from one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, vinyl silane coupling agent, bis-[γ-(triethoxysilyl)propyl]tetrasulfide and γ-glycidyloxypropyltrimethoxysilane.

9. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The acid anhydride curing agent is selected from one or more of aromatic acid anhydride, aliphatic acid anhydride, aliphatic acid anhydride, halogen-containing acid anhydride, and low eutectic point acid anhydride; And / or, the accelerator is selected from one or more of organic amine salts, acetylacetonate metal salts, triphenylphosphine or phosphonium salts, organic carboxylates and halide quaternary ammonium salts.

10. The high temperature resistant and yellowing resistant LED packaging glue according to claim 1, characterized in that: The particle size of the diffusion powder is 1-5 μm, and the density is 1-3 g / cm 3 ; And / or, the matte powder has a particle size of 4-7 μm and a density of 0.1-0.5 g / cm 3 ; And / or, the whiteness hue of the diffusion powder and the matte powder is ≥92%.

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