A heat-aging-resistant, toluene-resistant, high-light-shielding PC plastic and its preparation method and application

Abstract

The invention discloses a heat-resistant, toluene-resistant, high-light-shielding PC plastic and its preparation method and application. In terms of weight, the raw material composition includes: 75-90 parts of PC resin, 1-2 parts of anti-aging agent, 7-25 parts of light-shielding agent, and 0.1-3 parts of other auxiliary agents. The preparation method includes the steps of: mixing all the raw materials evenly according to the ratio, feeding them into a twin-screw extruder through the main feed for plasticization, exhausting, re-plasticization, vacuuming, decompression, extrusion and granulation. The high temperature and high humidity resistant flame-retardant PC plastic of the present invention is suitable for LED lighting appliances, IT, mobile phones, etc.

Description

Technical Field

[0001] The invention relates to the technical field of engineering plastics, and in particular to a PC plastic that is resistant to heat aging, toluene and high in light shielding, and a preparation method and application thereof. Background Art

[0002] PC resin is a high molecular polymer made by polycondensation of bisphenol A and diphenyl carbonate or phosgene. PC has excellent comprehensive performance and many advantages. Its impact resistance is the best among thermoplastics. PC has good tensile strength and bending strength, and is less affected by temperature. PC has good creep resistance and dimensional stability. Thermal properties: PC has good high and low temperature resistance and can be used in the temperature range of -130 to 130°C. Its thermal conductivity and linear expansion coefficient are relatively small, and it has good flame retardancy and is a self-extinguishing material. The electrical properties of PC change little over a wide temperature and temperature range. The light transmittance of PC can reach 89%, which is second only to plexiglass among transparent plastics.

[0003] PC has an increasingly important position in the LED field due to its unique high light transmittance, high refractive index, high impact resistance, excellent dimensional stability and easy processing and molding characteristics among engineering plastics. Various optical materials made of optical-grade PC are unmatched by traditional inorganic glass in terms of impact resistance and molding processing performance.

[0004] Although PC has many advantages, the conventional PC light transmittance is 88-90%, which cannot meet the light-proof requirements of the LED light shielding part. In order to reduce the light transmittance of PC and improve the light shielding effect of PC materials, a large amount of sunscreen agents need to be added for modification. These sunscreen agents are mostly inorganic particles, such as titanium dioxide, zinc oxide, glass beads, carbon black, etc. These inorganic powders have poor compatibility with PC. While improving the light shielding effect, they are prone to uneven dispersion, which can cause a serious decrease in the toughness of PC materials. The temperature rise of high-power LED lamps can reach 100 degrees during operation. Under high temperatures, sunscreen agents will accelerate the catalytic degradation of PC, and parts often break after long-term use.

[0005] At the same time, when LED is packaged, its packaging resin contains trace amounts of organic solvents such as toluene. The volatilization of toluene at a high temperature of 180-110 degrees will induce stress cracking of the light-shielding PC. The light-shielding outer surface of the finished LED lamp may be sprayed or labeled for aesthetic purposes. The organic solvents in the spraying or labeling will also swell the PC. Long-term use at high temperatures may cause stress cracking of the light-shielding PC.

[0006] A large number of literatures have shown that the long-term aging resistance of materials is improved by adding antioxidants, the toluene resistance of materials is improved by adding ABS, PBT, PET, and olefin elastomers to prepare alloyed PC, and the shading rate of materials is improved by increasing the amount of shading agents.

[0007] A Chinese patent document with publication number CN 104962056 A discloses a high light-shielding PC material and a method for manufacturing the same, which improves the toughness of the material by modifying titanium dioxide with organic silicone oil, but no data on solvent resistance and long-term aging under high light-shielding conditions are found.

[0008] A Chinese patent document with publication number CN110734653A discloses a light-shielding, high-temperature-resistant, flame-retardant PC material and a method for manufacturing the same. The material improves its temperature resistance by using a sulfonate flame retardant instead of a bromine-based flame retardant and a phosphate flame retardant, but no data on solvent resistance and long-term aging under high light-shielding conditions are found.

[0009] The technical solutions disclosed in the above patents are to improve the light-shielding property of the material by adding a large amount of sunscreen to the matrix PC resin; alloying PC to improve the material's resistance to toluene, and adding high-temperature-resistant antioxidants to improve the material's long-term thermal aging resistance. However, these solutions all have extremely obvious side effects, such as the large amount of sunscreen added makes it difficult to disperse the sunscreen in PC and has poor impact; alloying PC leads to a serious decrease in the material's heat resistance and flame retardancy; adding antioxidants is only effective for material aging at room temperature, but does not improve the long-term aging of the parts at high temperatures, even if the amount of antioxidant is increased. Since the fields of LEDs, mobile phones, etc. have strict requirements and certifications for the comprehensive performance of materials (solvent resistance, thermal aging, sunscreen, flame retardancy), the comprehensive performance of the products in the above technical solutions cannot meet the requirements, and the application is greatly limited. Summary of the invention

[0010] In order to overcome the problem in the prior art that spray-coated or silk-screen-printed light-shielding PC plastic products are prone to breakage due to long-term heat aging, the present invention provides a method for preparing heat-aging-resistant, toluene-resistant and high-light-shielding PC plastic.

[0011] A heat-resistant, toluene-resistant, high-light-shielding PC plastic, the raw materials of which are composed of the following components by weight:

[0012] 80-90 parts of PC resin,

[0013] 1-2 parts of anti-aging agent,

[0014] Sunscreen 2-10

[0015] Other additives 0.1~3 parts.

[0016] The inventors have unexpectedly discovered through a large number of experiments that the use of anti-aging additives in the PC composition formula can not only significantly improve the long-term heat aging resistance of the light-shielding PC composition, but also can replace part of the light-shielding agent to significantly improve the light-shielding performance, and the anti-aging additives also improve the PC toluene solvent resistance. The resulting flame-retardant PC plastic has good light-shielding properties, excellent long-term heat aging properties, and good toluene additive resistance, and is particularly suitable for LED lighting appliances, IT, and mobile phone industries.

[0017] The PC resin is selected from bisphenol A type PC produced by ester exchange method and phosgene method, and the melt flow rate of the PC resin under the conditions of 300° C. and 1.2 kg is 9-25 g / 10 min.

[0018] The anti-aging agent can be a high molecular polymer with epoxy functional groups, such as acrylonitrile-styrene-glycidyl ester terpolymer, epoxy grafted silicon acrylate core-shell polymer, etc.

[0019] The sunscreen is rutile titanium dioxide with a particle size of 150-300um, preferably produced by chlorination method with a diameter of 150-200um, and the surface is treated with inorganic and organic double-layer coating.

[0020] In addition, in order to improve other properties of the product, other additives can be adaptively added, including common lubricants, flame retardants, anti-dripping agents, etc.

[0021] The lubricant can be one or more of the commonly used lubricants in the art, and specifically can be selected from one or more of amide lubricants, PE wax lubricants, silicone lubricants and ester lubricants.

[0022] The invention also discloses a preparation method of the heat-resistant, toluene-resistant and high-light-shielding PC plastic, which comprises the steps of: uniformly mixing all raw materials according to a proportion, feeding them into a twin-screw extruder through a main feeder for plasticization, exhausting, re-plasticization, vacuuming, reducing pressure, and extruding and granulating to obtain the PC plastic.

[0023] Preferably, the screw aspect ratio of the twin-screw extruder is 36:1, and the screw speed is 350-450 rpm.

[0024] It has been found through experiments that the use of the above process conditions combined with the above formula composition can further improve the heat aging resistance, toluene resistance and light-shielding properties of the PC material.

[0025] The invention also provides the application of the heat-aging-resistant, toluene-resistant and high-light-shielding PC plastic in LED lighting appliances, IT and mobile phones.

[0026] Compared with the prior art, the present invention has the following main advantages:

[0027] The heat-resistant, toluene-resistant, high-light-shielding PC plastic of the present invention mainly solves the problem of serious degradation of physical properties of LED light-shielding PC materials when used in high-temperature environments; at the same time, it solves the problem of PC cracking due to residual toluene solvent during LED painting, silk-screen printing, and packaging. At the same time, by selecting a heat-resistant aging agent and utilizing the difference in refractive index between it and PC resin to form a pearlescent effect, the amount of light-shielding agent can be greatly reduced to replace part of the light-shielding agent, greatly improving the toughness and long-term aging resistance of the material. Therefore, by optimizing the formula, the long-term aging resistance and resistance to organic solvent toluene of the material are improved while satisfying the light-shielding characteristics of the material, and it is particularly suitable for indoor and outdoor use in high-temperature environments and spraying LED lighting appliances, IT, and mobile phones. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. Specific Tables 1 and 2.

[0029] The performance test standards and methods are as follows:

[0030] Tensile strength: measured according to GB / T1040.2-2006, test conditions: temperature 23°C, air humidity 50%, tensile speed, 20mm / min;

[0031] Tensile strength retention rate (high temperature): Tensile strength retention rate = tensile strength (after high temperature) / tensile strength × 100%;

[0032] Simply supported beam impact strength: measured according to GB / T1043.1-2008: test conditions: temperature 23°C, air humidity 50%, pendulum energy 4 J;

[0033] Simply supported beam notch impact strength retention rate (high temperature): Simply supported beam notch strength retention rate = Simply supported beam notch strength (after high temperature aging) / Simply supported beam notch strength × 100%;

[0034] Simply supported beam notched impact strength retention rate (toluene): Simply supported beam notched strength retention rate = Simply supported beam notched strength (toluene) / Simply supported beam notched strength × 100%;

[0035] Flame retardant test: According to GB / T2408-2008 standard, the test specimen thickness is 1.6 mm;

[0036] Light transmittance test: According to GB / T2410-2008 standard, the test strip is 50mm long, 50mm wide and 1mm thick.

[0037] High temperature aging test: put the tensile, impact and flame retardant specimens into the test environment at a temperature of 100℃ and conduct 1000 h aging test.

[0038] Notched impact strength (toluene resistance) test: Soak the notched impact specimen in a 99.9% analytical pure toluene solution for 10 minutes, then place it in a 100-degree oven for 1 hour, and cool it to room temperature of 23 degrees for toluene resistance notched impact strength test.

[0039] The raw material ratios and performance test results of the PC plastics of Examples 1 to 8 and Comparative Examples 1 to 8 are shown in Tables 1 and 2, respectively. The test results are rounded to a certain number of significant digits.

[0040] The raw material grades and sources in Tables 1 and 2 are as follows:

[0041] PC: 1920T-11 Melt index 20 g / 10 min (300℃, 1.2 kg) Shandong Luxi Chemical;

[0042] Heat aging agent 1: EXL-2314 rubber core particle size 180-240nm epoxy grafted core-shell acrylate American DOW Company;

[0043] Heat aging agent 2: S2200 rubber core particle size 120-160nm epoxy grafted core-shell silicone acrylate Japan Mitsubishi Rayon;

[0044] Heat aging agent 3: SAG-008 Glycidyl methacrylate grafted acrylonitrile-styrene Shanghai Rizhisheng Company;

[0045] Sunscreen 1: R103 titanium dioxide, rutile type, DuPont, USA;

[0046] Sunscreen 2: R-216 titanium dioxide, rutile type, China National Nuclear Huayuan Titanium Dioxide Company;

[0047] Sunscreen 3: KRONOS2233, rutile type, KRONOS, Germany;

[0048] Flame retardant: FR-5100 (potassium perfluorobutanesulfonate) Dongguan Quansheng Chemical;

[0049] Lubricant: P861 / 3.5 ester lubricant from Corning, Germany;

[0050] Antioxidant: S-9928 phosphite antioxidant, American Dow Chemical Company

[0051] Other additives: B449 anti-drip agent AS coated polytetrafluoroethylene GE fine chemicals.

[0052] The preparation methods of PC plastics in Examples 1 to 8 and Comparative Examples 1 to 8 are the same, including the steps of: mixing all raw materials in a uniform ratio and then feeding them into a twin-screw extruder through a main feeder for plasticization, exhausting, re-plasticization, vacuuming, decompressing, and extruding and granulating. The twin-screw extruder has a screw length-to-diameter ratio of 36:1 and a screw speed of 400 rpm.

[0053] Table 1 Specific proportions (parts by weight) of Examples 1 to 8 and their test performance results

[0054]

[0055] Table 2 Specific proportions (weight parts) of comparative examples 1 to 8 and their test performance results

[0056]

[0057] From the comparison of each embodiment 1-8 and comparative example 1-8 in Tables 1 and 2, it can be seen that by adding heat-resistant aging additives instead of antioxidants, the long-term heat aging, toughness, flame retardancy and light-shielding properties of the material can be significantly improved by shading. Among them, Mitsubishi Rayon S2200 has better physical properties, and its optimal addition amount is 1.5%. It not only has the best long-term heat aging properties, but also has the highest toluene resistance. Under the condition of using 20-30% less sunscreen, its light-shielding effect and toughness are both good; different sunscreens will affect the various short-term physical properties of the material. It can be seen from the table that the sunscreen Connos 2233 titanium dioxide has better physical properties than other sunscreens, but the degree of change in long-term aging physical properties is not much different. While significantly improving the high temperature and high humidity resistance of flame-retardant PC materials, it will not cause the degradation of other properties, and can meet the strict requirements of LED lighting appliances, IT, mobile phones, and other fields for the comprehensive performance of materials.

[0058] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A heat aging resistant, toluene resistant, high light shielding PC plastic, characterized in that: The raw material composition includes, by weight: 75 to 90 parts of PC resin, 1 to 2 parts of anti-aging agent, 7 to 25 parts of sunscreen agent, and 0.1 to 3 parts of other additives; the anti-aging agent is S2200 of Mitsubishi Rayon of Japan, and the sunscreen agent is rutile titanium dioxide.

2. The heat aging resistant, toluene resistant, high light shielding PC plastic according to claim 1, characterized in that: The PC resin is selected from bisphenol A PC produced by phosgene method or transesterification method, and the melt flow rate of the PC resin at 300° C. and 1.2 kg is 9 to 25 g / 10 min.

3. The heat aging resistant, toluene resistant, high light shielding PC plastic according to claim 1, characterized in that: The particle size of the sunscreen used is between 150 and 300 μm.

4. The heat aging resistant, toluene resistant, high light shielding PC plastic according to claim 1, characterized in that: The other auxiliary agents include one or more of an anti-dripping agent and a lubricant.

5. The method for preparing the heat-resistant, toluene-resistant and high-light-shielding PC plastic according to any one of claims 1 to 4, characterized in that All raw materials are mixed evenly according to the ratio and then fed into a twin-screw extruder through the main feed for plasticization, exhaust, re-plasticization, vacuumization, decompression, and extrusion granulation. The twin-screw extruder has a screw length-to-diameter ratio of 36:1 and a screw speed of 350-450 rpm.

6. Application of the heat-aging-resistant, toluene-resistant and high-light-shielding PC plastic according to any one of claims 1 to 4 in LED lighting appliances and IT.

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