Polyester resin composition, its manufacturing method and use

Abstract

The present invention relates to a polyester resin composition, its manufacturing method and use. The polyester resin composition includes PCT resin, white pigment, reinforcing material, polyester elastomer and other additives. The polyester resin composition according to the present invention has a strong bond with silicone, and when used as an LED reflector bracket, the LED reflector bracket and silicone are not easily separated even under high temperature and high humidity conditions, which is effective in extending the life of LED lamp beads. In addition, the polyester resin composition has excellent toughness and does not cause the problem of powder falling off when subjected to repeated force.

Description

[Technical Field]

[0001] The present invention belongs to the technical field of thermoplastic resins, and in particular to a polyester resin composition, its preparation method and use. [Background technology]

[0002] With the birth of light-emitting diodes (LEDs), the lighting industry entered the era of semiconductor lighting. LED light sources have the advantages of high reliability, high luminous power, low power consumption, fast response time, long life, low price, and a wide range of colors. Following gas lighting, incandescent lamps, and fluorescent lamps, LEDs have become the mainstream lighting technology of the new generation. With the development of the times and the advancement of science and technology, LEDs are widely used in various fields such as street lighting, indoor lighting, backlight displays, car headlights, and landscape lighting.

[0003] LED brackets act as chip carriers, conducting both electricity and heat, making them an essential auxiliary material for LED devices. Materials used for LED brackets include high-temperature polyamide (PPA) and high-temperature polyester (poly(cyclohexyldimethylene terephthalate), PCT). High-temperature polyamide (mainly PA46, PA6T, and PA9T) is currently the mainstream material for LED brackets due to its high initial whiteness, excellent heat resistance, high fluidity, suitability for injection molding processes, and low cost. However, PPA materials suffer from rapid photothermal degradation and decay, so they are currently only suitable for low-power products. With the introduction of high-voltage LEDs, PCT offers significant advantages for use in reflector brackets for medium- and high-power LEDs due to its excellent resistance to high-temperature discoloration.

[0004] The LED packaging process includes pre-baking the reflector bracket, die bonding, wire bonding, adhesive dispensing, separation, spectroscopy, and taping. Separation refers to the process of passing the die-bonded, wire-bonded, and adhesive-dispensed metal strip containing the LED lamp beads through an automatic peeling machine, which then presses and peels each LED bead off the metal strip. The protrusions of the metal strip are embedded in the grooves of the LED reflector bracket, and the automatic peeling machine repeatedly presses and peels the LED bead off. During this process, an interaction force occurs between the metal strip and the LED reflector bracket. LED reflector brackets made of PCT material have poor toughness and can break under repeated stress, resulting in powder shedding, which leads to the disposal of the LED reflector bracket and other problems, seriously affecting the subsequent packaging process.

[0005] LED packaging adhesives primarily contain epoxy resin and silicone. Silicone boasts excellent mechanical properties, aging resistance, excellent thermal stability, weather resistance, flexibility, high light transmittance, low internal stress, and low moisture absorption, making it more suitable for packaging high-power, high-brightness LED products. Therefore, silicone is rapidly replacing epoxy resin as the ideal LED packaging material for the new generation. However, LED reflector brackets made of PCT material have a weak bond with silicone, which can lead to separation between the LED reflector bracket and silicone during actual use. This separation allows oxygen and water vapor from the air to penetrate into the LED lamp bead, resulting in lamp failure and a shortened lifespan.

[0006] Patent CN102471565A discloses a flame-retardant polymer composition that solves the problem of reduced mechanical properties (elongation at break and abrasion resistance) when a flame retardant is introduced by adding a specific polyester elastomer. The resulting composition has excellent flame retardancy and excellent mechanical properties (elongation at break and abrasion resistance), and maintains these properties at a high level even after heat aging. However, this composition is primarily used to manufacture ultra-fine cables, and does not take into consideration issues such as the bonding strength between the polyester resin composition and silicone, powder shedding during the LED package separation process when used as an LED light-emitting substrate, and the lifespan of LED lamp beads.

[0007] Therefore, the development of a new polyester composition material that has strong bonding strength with silicone, prevents separation of the LED reflector bracket and silicone during the LED package separation process, and extends the life of the LED lamp bead. It also has strong toughness and will not break even when subjected to repeated stress, thereby avoiding the problem of powder shedding, has great research significance and application value. Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a polyester resin composition that overcomes the conventional problems of poor bonding strength between the polyester resin composition and silicone, which leads to easy separation of the LED reflective bracket and silicone during the LED package separation process, shortening the life of the LED lamp beads, and ineffectively preventing poor or insufficient powder shedding during the LED package separation process. The polyester composition of the present invention has strong bonding strength with silicone, and when used as an LED reflective bracket, the LED reflective bracket and silicone are unlikely to separate even in high-temperature, high-humidity environments, which is effective in extending the life of the LED lamp beads. In addition, it has excellent toughness, so the problem of powder shedding does not occur when repeatedly subjected to force.

[0009] Another object of the present invention is to provide a method for producing the above polyester resin composition.

[0010] Another object of the present invention is to provide a use of the polyester resin composition in the manufacture of LED products. [Means for solving the problem]

[0011] In order to achieve the above object of the invention, the present invention adopts the following technical solutions:

[0012] A polyester resin composition comprising: The composition comprises 40 to 80 parts by weight of a PCT resin, 10 to 40 parts by weight of a white pigment, 0 to 30 parts by weight of a reinforcing material, 0.5 to 5 parts by weight of a polyester elastomer, and 0 to 10 parts by weight of other additives; It contains a polyester hard segment and a polyether soft segment, has a Shore hardness of 40 to 74, and a melting point of 191 to 221°C.

[0013] The polyester resin composition of the present invention uses PCT resin as the matrix, and white pigment is added to adjust the color. A specific polyester elastomer is added to enhance the bonding strength and toughness with the silicone, preventing the separation of the LED reflector bracket and silicone during the LED package separation process, thereby extending the life of the LED lamp bead and preventing the problem of powder shedding when subjected to repeated force. The specific operating principle is as follows:

[0014] The polyester elastomer is composed of a polyester hard segment and a polyether soft segment, where the polyester hard segment provides good compatibility with the polyester matrix, and the polyether soft segment provides good toughness and adhesion. Through repeated research, the inventors discovered that by adjusting the specific hardness and melting point, it is possible to balance the improving effects of the polyester hard segment and the polyether soft segment. The resulting polyester composition has high notched impact strength, and LED reflector brackets made from the polyester composition are less likely to break when subjected to the force of a metal strip during bead peeling, thereby avoiding the problem of powder shedding.

[0015] On the other hand, the polyether soft segments of polyester elastomers with specific hardness and melting points contain a large amount of hydroxyl groups and ether bond active groups, which can undergo a chemical reaction with the silicon hydrogen groups on the silicone surface, further improving the bonding strength between the polyester resin composition and silicone, eliminating the problem of separation between the LED reflective bracket and silicone even in high-temperature, high-humidity environments, and extending the life of LED lamp beads.

[0016] Furthermore, the toughness can be further improved by adding an appropriate amount of reinforcing material.

[0017] Preferably, the polyester resin composition contains, as a component: It contains 50 to 70 parts by weight of PCT resin, 20 to 35 parts by weight of white pigment, 5 to 20 parts by weight of reinforcing material, 1 to 4 parts by weight of polyester elastomer, and 2 to 8 parts by weight of other additives.

[0018] Preferably, the polyester elastomer is a polyester-ether type, has a Shore hardness of 46 to 63, and a melting point of 195 to 212°C.

[0019] Any PCT resin, white pigment, reinforcing material, and suitable additives conventional in the art can be used in the present invention.

[0020] PCT resin has the structural formula (see Chemical Formula 1 below) obtained by polycondensation reaction of terephthalic acid and 1,4-cyclohexanedimethanol. [ka]

[0021] Preferably, the intrinsic viscosity of the PCT resin is 0.65 to 0.75 dL / g.

[0022] The test method for intrinsic viscosity is to weigh 0.5 g of sample and dissolve it in 100 mL of 60 / 40 (wt / wt) phenol / tetrachloroethane, and then perform the intrinsic viscosity test using an Ubbelohde viscometer at a constant temperature of 25°C.

[0023] Preferably, the PCT resin has an intrinsic viscosity of 0.71 to 0.73 dL / g.

[0024] Preferably, the white pigment is one or more of titanium dioxide, zinc oxide, zinc sulfide, white lead, zinc sulfate, barium sulfate, calcium carbonate, or alumina.

[0025] More preferably, the white pigment is titanium dioxide.

[0026] Preferably, the reinforcing material is one or more of glass fibre, wollastonite, potassium titanate whiskers, kaolin, talc or mica.

[0027] Preferably, the other additives are one or more of an antioxidant (0 to 3 parts by weight), an impact modifier (0 to 10 parts by weight), a flame retardant (0 to 10 parts by weight), a fluorescent whitening agent (0 to 5 parts by weight), a lubricant (0 to 5 parts by weight), a plasticizer (0 to 5 parts by weight), a thickener (0 to 3 parts by weight), an antistatic agent (0 to 3 parts by weight), a nucleating agent (0 to 3 parts by weight), a UV stabilizer (0 to 2 parts by weight), a release agent (0 to 3 parts by weight), a pigment (0 to 10 parts by weight), or a dye (0 to 10 parts by weight).

[0028] The method for producing the polyester resin composition includes the steps of mixing a PCT resin, a white pigment, a reinforcing material, a polyester elastomer and other additives, melt-extruding the mixture, and granulating the mixture to obtain the polyester resin composition.

[0029] The use of the polyester resin composition in the manufacture of LED products is also within the scope of protection of the present invention.

[0030] Preferably, the LED product is an LED reflector bracket. [Effects of the Invention]

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The polyester resin composition of the present invention has a strong bonding strength with silicone, and when made into an LED reflective bracket, the LED reflective bracket and silicone are unlikely to separate even in high-temperature, high-humidity environments, making it effective in extending the life of LED lamp beads.In addition, it has excellent toughness and does not cause problems with powder falling off when subjected to repeated force. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be further described below with reference to examples. These examples are used only to illustrate the present invention and are not used to limit the scope of the present invention. In the following examples, experimental methods for which specific conditions are not specified generally follow the usual conditions in the art or the conditions suggested by the manufacturer, and raw materials, reagents, etc. used are available from commercial channels such as ordinary markets unless otherwise specified. Any insubstantial modifications and substitutions made by those skilled in the art based on the present invention are within the scope of protection of the present invention.

[0034] Some of the reagents used in the examples and comparative examples of the present invention will be explained below.

[0035] PCT Resin 1#: Eastman™ Chemical Products, PCT 36296, intrinsic viscosity 0.719 dL / g (0.5 g of sample was weighed and dissolved in 100 mL of 60 / 40 (wt / wt) phenol / tetrachloroethane, and the intrinsic viscosity test was performed using an Ubbelohde viscometer at a constant temperature of 25°C. The same applies below.).

[0036] PCT resin 2#: SK Chemicals, 0302, intrinsic viscosity: 0.65 dL / g. PCT resin 3#: SK Chemicals, 0502, intrinsic viscosity: 0.75 dL / g. PCT Resin 4#: Eastman™ Chemical Products, PCT 36294, intrinsic viscosity 0.625 dL / g. White pigment: titanium dioxide (TiO2), R105, manufactured by DuPont Co., Ltd. (USA); zinc oxide (ZnO), UN3077, manufactured by LANXESS Chemical (China) Co., Ltd. Reinforcement: F7x28: CSG3PA-820 manufactured by NITTO BOSEKI Japan, fiber diameter 28 μm, wollastonite, NYGLOS 8 manufactured by NYCO Minerals, USA. Polyester-ether type polyester elastomer: manufactured by Royal DSM, Netherlands, model numbers Arnitel (registered trademark) EM400 (Shore hardness 40, melting point 191°C), EM460 (Shore hardness 46, melting point 195°C), EM550 (Shore hardness 55, melting point 207°C), EM630 (Shore hardness 63, melting point 212°C), EM740 (Shore hardness 74, melting point 221°C); manufactured by DuPont Co., Ltd. (USA), model number 8238 (Shore hardness 82, melting point 221°C), model number 4056 (Shore hardness 40, melting point 150°C). Shore hardness was measured according to GB / T 2411-2008. Melting point was measured according to ASTM D3418-2003. Polyester-polyester type polyester elastomer: Arnitel (registered trademark) UM551 (Shore hardness 55, melting point 200°C) manufactured by Royal DSM, Netherlands. Silicone: LED packaging silicone UH-6950-1 (consisting of adhesive A and adhesive B) purchased from Shenzhen Yongxin Technology Co., Ltd.

[0037] The polyester resin compositions in the examples and comparative examples of the present invention and the test specimens required for the tests are prepared as follows.

[0038] The dried PCT resin and polyester elastomer are uniformly mixed in a high-speed mixer and added to the main feed port of a twin-screw extruder, after which the white pigment, reinforcing filler, and other additives (if present) are added to the twin-screw extruder from a side feeder, and the mixture is melt-extruded and granulated using the twin-screw extruder at a set temperature of 230 to 300°C to obtain a granular polyester resin composition.

[0039] The test methods for the examples and comparative examples of the present invention are as follows.

[0040] Impact Strength Test: Notched Izod impact strength is tested according to ISO 180-2013.

[0041] Powder shedding test: The resulting polyester composition was injection molded into 28mm x 35mm square 2835 model LED reflector brackets, with 36 x 22 = 792 LED reflector brackets per metal strip. The beads were removed from the injection-molded LED brackets using an automatic peeling machine. After all LED brackets had been peeled, the number of broken LED brackets was recorded to simulate powder shedding after packaging into lamp beads. If the number of broken LED reflector brackets was 100 or less, the product met the requirements for use.

[0042] Tensile breaking strength test Test specimen preparation: Polyester resin composition test specimens measuring 80 x 20 x 2.0 mm were injection molded. Test method: Adhesive A and Adhesive B were uniformly mixed in a 1:4 mass ratio, and 0.02 g of the mixture was dropped onto one end of one test piece. One end of the other test piece was held to silicone and secured with a clip. The test piece was then placed in an oven and pre-cured at 80°C for 1 hour. The temperature was then raised to 150°C and cured for 4 hours, after which the cured spline was subjected to a tensile test at a tensile speed of 10 mm / min, and the tensile break strength was recorded. In this application, the tensile break strength represents the bonding strength between a molded product made from the polyester composition and silicone. The higher the tensile break strength, the stronger the bonding strength between the molded product made from the polyester composition and silicone. A tensile break strength of 350 N or greater meets practical needs.

[0043] Examples 1 to 18 In this example, a series of polyester resin compositions are provided in which the parts by weight of each component in the formulation are shown in Tables 1 and 2.

[0044] [Table 1]

[0045] [Table 2]

[0046] Comparative Examples 1 to 4 This comparative example provides a series of polyester resin compositions in which the parts by weight of each component in the formulation are shown in Table 3.

[0047] [Table 3]

[0048] The performance of the polyester resin compositions of the examples and comparative examples was tested using the above-mentioned performance test methods, and the results shown in Tables 1, 2 and 3 were obtained.

[0049] The above results indicate that the polyester compositions of Examples 1 to 18 have excellent toughness and high notch impact strength. The resulting LED reflector brackets broke fewer than 100 pieces when the beads were peeled off. The polyester resin composition also bonded strongly to silicone, with a tensile break strength of 324 N or greater. In Examples 1 to 5, elastic polyurethanes with different Shore hardnesses were used. As hardness increased, the notch impact strength increased and then decreased. The bonding strength between the polyester resin composition and silicone also increased and then decreased. When the Shore hardness was 46 to 63, the notch impact strength and the bonding strength with silicone further improved. The tensile break strength was 558 N or greater. The resulting LED reflector brackets broke fewer than 20 pieces when the beads were peeled off. In Examples 3, 6, and 7, increasing the amount of elastic polyurethane used increased and then decreased the notch impact strength, with Example 3 showing the best performance.

[0050] In Comparative Example 1, the resin was not modified with elastic polyurethane, resulting in low notch impact strength and poor bonding strength between the polyester resin composition and silicone. When used as an LED reflector bracket, the number of breakages upon bead peeling exceeded 600, and the tensile break strength was only 157 N. In Comparative Example 2, the LED reflector bracket manufactured using a polyester-polyester type polyester elastomer exceeded 580 breakages upon bead peeling, and the tensile break strength was only 167 N. In Comparative Example 3, the LED reflector bracket manufactured using a polyester elastomer with a hardness of 84 and a melting point of 221°C, the number of breakages upon bead peeling was 393, and the tensile break strength was 304 N, resulting in poor improvement. In Comparative Example 4, the LED reflector bracket manufactured using a polyester elastomer with a hardness of 40 and a melting point of 150°C, the number of breakages upon bead peeling was 423, and the tensile break strength was 281 N, resulting in poor improvement.

[0051] Those skilled in the art will recognize that the above examples are intended to help readers understand the principles of the present invention, and should be understood as meaning that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific modifications and combinations according to the technical suggestions disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations will still fall within the scope of protection of the present invention.

Claims

1. The composition contains 40 to 80 parts by weight of PCT resin, 10 to 40 parts by weight of white pigment, 0 to 30 parts by weight of reinforcing material, 0.5 to 5 parts by weight of polyester elastomer, and 0 to 10 parts by weight of other additives, The polyester elastomer contains a polyester hard segment and a polyether soft segment, has a Shore hardness D of 40 to 74, and a melting point of 191 to 221°C, A polyester resin composition, wherein the polyether soft segment of the polyester elastomer contains a hydroxyl group.

2. 2. The polyester resin composition according to claim 1, comprising, as components, 50 to 70 parts by weight of PCT resin, 20 to 35 parts by weight of white pigment, 5 to 20 parts by weight of reinforcing material, 1 to 4 parts by weight of polyester elastomer, and 2 to 8 parts by weight of other additives.

3. 2. The polyester resin composition according to claim 1, wherein the polyester elastomer is a polyester-ether type, has a Shore hardness D of 46 to 63, and a melting point of 195 to 212°C.

4. 2. The polyester resin composition according to claim 1, wherein the PCT resin has an intrinsic viscosity of 0.65 to 0.75 dL / g.

5. 2. The polyester resin composition according to claim 1, wherein the white pigment is one or more of titanium oxide, zinc oxide, zinc sulfide, white lead, zinc sulfate, barium sulfate, calcium carbonate, and alumina.

6. 2. The polyester resin composition according to claim 1, wherein the reinforcing material is one or more of glass fiber, wollastonite, potassium titanate whisker, kaolin, talc, and mica.

7. 2. The polyester resin composition according to claim 1, wherein the other additives are one or more of an antioxidant, an impact modifier, a flame retardant, a fluorescent whitening agent, a lubricant, a plasticizer, a thickener, an antistatic agent, a nucleating agent, a UV stabilizer, a release agent, a pigment, or a dye.

8. 8. A method for producing a polyester resin composition according to claim 1, comprising the steps of: mixing a PCT resin, a white pigment, a reinforcing material, a polyester elastomer, and other additives; melt-extruding the mixture; and granulating the mixture to obtain the polyester resin composition.

9. Use of the polyester resin composition according to any one of claims 1 to 7 in the manufacture of LED products.

10. Use of the polyester resin composition according to claim 9 in the manufacture of an LED product, comprising: The LED product is an LED reflector bracket.

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