Long-term aging-resistant compounded antioxidant for PC and preparation method therefor

Abstract

The present invention relates to the field of antioxidants, and in particular to a long-term aging-resistant compounded antioxidant for PC and a preparation method therefor. Raw materials for preparing the long-term aging-resistant compounded antioxidant for PC provided by the present invention include a phosphite antioxidant, a hindered amine antioxidant, a thioester antioxidant, and a light stabilizer, wherein the mass ratio of the phosphite antioxidant to the hindered amine antioxidant to the thioester antioxidant to the light stabilizer is (5-8): (1-3): (1-2): (1-2). The four raw material components of the long-term aging-resistant compounded antioxidant for PC in the present invention have a synergistic effect. In practical applications, PC processing-derived products exhibit relatively low YI values after extrusion at 280°C and 300°C and aging at 80°C for 15 days, thereby providing PC materials with excellent long-term aging-resistance.

Description

A long-lasting, aging-resistant compound antioxidant for PC and its preparation method Technical Field

[0001] This invention relates to the field of antioxidants, and more specifically, to a long-lasting, aging-resistant compound antioxidant for PC and its preparation method. Background Technology

[0002] Polycarbonate (PC) is a high-performance thermoplastic engineering plastic containing carbonate groups in its molecular chain. Due to its excellent overall properties, it is widely used in various industrial fields. PC material has high transparency, with a light transmittance of over 90%, and excellent impact resistance, reaching 250 times that of ordinary glass. Furthermore, its glass transition temperature (Tg) is approximately 147℃, giving it excellent heat resistance. Currently, PC material has become an important chemical raw material in the electronics, automotive, medical device, optics, building materials, and packaging industries. For example, in the electronics field, PC is used to manufacture mobile phone casings, laptop screens, and LED lamp covers; in the automotive industry, PC is used in headlight covers, dashboards, and sunroofs; and in the medical field, due to its high-temperature sterilization resistance, it is often used in the manufacture of clinical medical devices.

[0003] However, despite its many advantages, PC also has certain limitations in practical applications. First, PC has low hydrolytic stability, easily undergoing hydrolysis in high-temperature and high-humidity environments, leading to molecular chain breakage and a significant decrease in mechanical properties. Second, PC is sensitive to notches, easily cracking due to stress concentration upon impact, limiting its application in precision structural components. Furthermore, PC has poor resistance to organic chemicals, easily swelling or corroding when in contact with oils, solvents, or strong acids and alkalis, affecting its service life. More importantly, PC is susceptible to thermal oxidation and ultraviolet radiation during processing and use, triggering molecular chain degradation, causing yellowing and a significant increase in the yellowing index, severely impacting the aesthetics and optical stability of processed products.

[0004] During PC processing, high-temperature extrusion and injection molding processes exacerbate oxidation reactions. The traditional solution is to add antioxidants to inhibit oxidation. For example, Chinese invention patent application CN104419185A discloses a modified high-toughness PC, whose raw materials include PC, hindered phenolic antioxidant 1010, and phosphite antioxidant 168. Hindered phenolic antioxidants primarily capture free radicals, but their ability to decompose hydroperoxides is limited; while phosphites can decompose hydroperoxides, they cannot effectively terminate the chain reaction. Therefore, while simple binary or ternary compound antioxidants can improve short-term color protection during processing, their synergistic effect is insufficient under long-term heat aging or UV exposure, failing to maintain the required long-term aging resistance.

[0005] Studies show that the yellowing of PC due to aging is the result of multiple factors, including thermal oxidation, photo-oxidation, and the catalytic effect of trace metal ions. Therefore, there is an urgent need to develop a multi-component synergistic antioxidant system that can inhibit oxidative yellowing during high-temperature processing and has good compatibility with the PC matrix. This is of great significance for improving the practical application value of PC materials. Summary of the Invention

[0006] To address the aforementioned technical problems, the first aspect of this invention provides a long-lasting, aging-resistant compound antioxidant for PC, the raw materials of which include antioxidants and light stabilizers; the antioxidants include at least three of the following: hindered phenolic antioxidants, phosphite antioxidants, hindered amine antioxidants, and thioester antioxidants.

[0007] As an implementable example, the grades of the hindered phenolic antioxidants include one or more of the following: antioxidant 1010, antioxidant 1076, antioxidant 2246, or antioxidant BHT (2,6-di-tert-butyl-4-methylphenol).

[0008] Hindered phenolic antioxidants are a class of phenolic compounds with sterically hindered structures, primarily used to prevent the aging and degradation of polymeric materials due to oxidation. The mechanisms of action of hindered phenolic antioxidants include scavenging free radicals, terminating free radical chain reactions, decomposing hydrogen peroxides, and synergistic effects with other antioxidants, thereby effectively delaying the oxidation process of materials.

[0009] As an implementable example, the phosphite antioxidants include: monophosphite antioxidants or diphosphite antioxidants.

[0010] As an implementable example, the grades of the monophosphite antioxidants include: Antioxidant 168 or Antioxidant TPP (triphenyl phosphite).

[0011] As an implementable example, the grades of the bisphosphite antioxidants include one or more of the following: antioxidant 626, antioxidant 618, antioxidant P-EPQ (tetra(2,4-di-tert-butylphenyl)-4,4'-biphenyl diphosphite) or antioxidant AS-4500 (4,4'-butylidene bis-(3-methyl-6-tert-butylphenyl)-tetra(tetrazyl) diphosphite).

[0012] Furthermore, the brand name of the phosphite antioxidant is Antioxidant 168.

[0013] The main mechanisms of action of phosphite antioxidants include: first, decomposing hydroperoxides and converting them into harmless alcohols, thereby inhibiting the propagation of free radical chain reactions; second, capturing peroxide free radicals and alkoxy free radicals, terminating free radical chain reactions, and reducing oxidative degradation; in addition, when phosphite antioxidants are used in combination with other types of antioxidants, they can significantly improve the heat resistance, color protection, and light stability of polymers such as PC.

[0014] As an implementable example, the grades of the hindered amine antioxidants include one or more of the following: antioxidant 944, antioxidant 770, antioxidant 711, antioxidant 622, antioxidant 783, antioxidant 292, antioxidant 123, or antioxidant 2020.

[0015] The mechanism of action of hindered amine antioxidants is primarily based on the activity of nitrile oxide (NO·) free radicals in their molecular structure. When polymeric materials are exposed to light and heat, a large number of reactive free radicals are generated, initiating a chain oxidation reaction and leading to material aging. Hindered amine antioxidants capture these free radicals and convert them into relatively stable compounds, thereby interrupting the propagation of the free radical chain reaction. Simultaneously, they can decompose hydroperoxides, preventing further decomposition and the generation of free radicals. Furthermore, hindered amine antioxidants can quench excited-state singlet oxygen, reducing the occurrence of photo-oxidation reactions. In addition, the nitrile oxide free radicals in hindered amine antioxidants have regenerative capabilities during the reaction process, allowing them to cyclically participate in the reaction and continuously exert a stabilizing effect, thus exhibiting long-lasting aging resistance and stability.

[0016] Furthermore, the hindered amine antioxidants include antioxidant 944.

[0017] As an implementable example, the grades of the thioester antioxidants include one or more of the following: antioxidant 636, antioxidant 412S, antioxidant DLTP (dilauryl thiodipropionate), antioxidant DSTDP (distearate thiodipropionate), or antioxidant DMTDP (dimyristyl thiodipropionate).

[0018] Furthermore, the brand name of the sulfur ester antioxidant is antioxidant DLTP.

[0019] As an implementable example, the light stabilizer includes one or more of the following: benzotriazole light stabilizers, triazine light stabilizers, hindered amine light stabilizers, and benzophenone light stabilizers.

[0020] As an implementable example, the grades of the benzotriazole light stabilizers include one or more of the following: Tinuvin 1130, Tinuvin 234, Tinuvin 328, Tinuvin 326, Tinuvin 384, Tinuvin 171, Tinuvin 900, Tinuvin 571, and Tinuvin 928.

[0021] As an example of an implementable approach, the triazine light stabilizer grades include one or more of Tinuvin 400, Tinuvin 477, Tinuvin 405, and Tinuvin 479.

[0022] As an implementable example, the grades of the hindered amine light stabilizers include one or more of Tinuvin 770, Tinuvin 292, Tinuvin 123, Tinuvin 144, and Tinuvin 152.

[0023] As an implementable example, the brands of the benzophenone light stabilizers include one or more of Tinuvin 531 (2-hydroxy-4-methoxybenzophenone), 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, and 2-hydroxy-4-octyloxybenzophenone.

[0024] Furthermore, the light stabilizer is designated Tinuvin 531.

[0025] Furthermore, the compound antioxidants for PC include phosphite antioxidants, hindered amine antioxidants, thioester antioxidants, and light stabilizers.

[0026] Furthermore, the mass ratio of the phosphite antioxidant, hindered amine antioxidant, thioester antioxidant and light stabilizer is (5-8):(1-3):(1-2):(1-2).

[0027] Furthermore, the grades of the compound antioxidants for PC include antioxidant 168, antioxidant 944, antioxidant DLTP, and Tinuvin 531 in a mass ratio of 6:2:1:1.

[0028] Antioxidant 168, as the main component of the compound antioxidant, can inhibit the propagation of free radical chain reactions by decomposing hydroperoxide (ROOH) into harmless alcohols (ROH). Simultaneously, it can also capture peroxide free radicals (ROO·) and alkoxy free radicals (RO·), terminating free radical chain reactions and reducing oxidative degradation. Antioxidant 944 inhibits photo-oxidation reactions by capturing free radicals and quenching singlet oxygen. Its generated nitroxide free radicals (NO·) have regenerative capabilities, can cyclically participate in reactions, and continuously exert a stabilizing effect. Antioxidant DLTP can decompose hydroperoxides in a superstoichiometric manner, generating stable alcohols, and further catalyzes the decomposition of hydroperoxides through the generated acidic substances such as sulfenic acid, enhancing antioxidant performance. Meanwhile, light stabilizer Tinuvin 531 absorbs ultraviolet light and converts it into harmless heat energy, preventing photo-oxidative degradation of PC materials due to ultraviolet radiation, further improving the product's long-term aging resistance.

[0029] In the compound system, antioxidant 168 and antioxidant 944 work synergistically; the former decomposes hydroperoxides, while the latter captures free radicals, jointly inhibiting the oxidation chain reaction. The thioester antioxidant DLTP further enhances the decomposition ability of hydroperoxides, especially under high-temperature conditions, providing additional thermal stability. A synergistic effect exists between the light stabilizer Tinuvin 531 and the hindered amine antioxidant 944. Under high-temperature aging conditions, the nitroxide free radicals generated by the hindered amine antioxidant interact with the alkyl hydroxylamine transition product of the light stabilizer, regenerating two active chain terminators, further improving the stabilizing effect. The synergistic effect of antioxidants 168, 944, DLTP, and Tinuvin 531 not only improves the stability of PC materials under high-temperature and light-exposed conditions but also significantly extends the product's service life.

[0030] The second aspect of the present invention provides a method for preparing a long-lasting and aging-resistant compound antioxidant for PC, comprising: mixing an antioxidant and a light stabilizer evenly to obtain a compound antioxidant for PC. Beneficial effects

[0031] (i) The compound antioxidant for PC provided by this invention has low YI (yellowing index) values ​​after actual use, when the product is extruded at 280℃ and 300℃ and aged at 80℃ for 15 days. Therefore, the compound antioxidant system can effectively protect the color stability of PC materials during processing and long-term use.

[0032] (II) In this invention, the compound antioxidants for PC utilize the following methods: By adding phosphite antioxidants, hydrogen peroxide can be effectively decomposed and free radicals captured; by adding hindered amine antioxidants, singlet oxygen can be effectively quenched and photo-oxidation reactions inhibited; by adding thioester antioxidants, the decomposition capacity of hydrogen peroxide can be effectively enhanced; and by adding light stabilizers, ultraviolet light can be effectively absorbed. The phosphite antioxidants, hindered amine antioxidants, thioester antioxidants, and light stabilizers work synergistically, thus significantly improving the heat resistance of PC materials and exhibiting better thermal stability during high-temperature processing and long-term aging.

[0033] (III) In this invention, the quaternary compound system of phosphite antioxidants, hindered amine antioxidants, thioester antioxidants and light stabilizers can not only play an inhibitory role in the long-term aging process of the product, but also effectively protect the color and performance of PC materials, so that they can maintain good appearance and physical properties in long-term use and extend the service life of the product.

[0034] (iv) In this invention, there is a synergistic effect between antioxidant 168, antioxidant 944, antioxidant DLTP and Tinuvin 531. The components work together to inhibit the oxidation chain reaction and improve the stability of PC material under high temperature and light conditions. Compared with ordinary binary and ternary compound antioxidant systems, it has a better long-term aging resistance effect.

[0035] (v) The compound antioxidant system provided by the present invention has good compatibility with PC material and will not have a negative impact on the processing performance of the material. It can play a stable role in processing such as high-speed stirring and twin-screw extrusion, ensuring the quality stability of the material during processing and improving production efficiency and product quality. Detailed Implementation

[0036] Example 1

[0037] The first aspect of this example provides a long-lasting, aging-resistant compound antioxidant for PC, which is prepared by the following raw materials in parts by mass: 6 parts of phosphite antioxidant, 2 parts of hindered amine antioxidant, 1 part of thioester antioxidant, and 1 part of light stabilizer.

[0038] The aforementioned phosphite antioxidant is designated as Antioxidant 168.

[0039] The hindered amine antioxidant is designated as Antioxidant 944.

[0040] The brand name of the sulfur ester antioxidant is antioxidant DLTP.

[0041] The light stabilizer is designated as Tinuvin 531.

[0042] The second aspect of this example provides a method for preparing a long-lasting and aging-resistant compound antioxidant for PC, specifically: mixing a phosphite antioxidant, a hindered amine antioxidant, a thioester antioxidant, and a light stabilizer evenly to obtain a compound antioxidant for PC; the product is designated as Antioxidant 1#.

[0043] Comparative Example 1

[0044] The first aspect of this example provides an antioxidant for PC, the raw materials for which are prepared by mass parts are: 2 parts hindered phenolic antioxidant and 8 parts phosphite antioxidant.

[0045] The aforementioned phosphite antioxidant is designated as Antioxidant 168.

[0046] The hindered phenolic antioxidant is designated as Antioxidant 1010.

[0047] The second aspect of this example provides a method for preparing an antioxidant for PC, specifically: a hindered phenolic antioxidant and a phosphite antioxidant are mixed evenly to obtain a compound antioxidant for PC; the product is designated as antioxidant #2.

[0048] Comparative Example 2

[0049] The first aspect of this example provides an antioxidant for PC, the raw materials for which are prepared by mass parts are: 6 parts of phosphite antioxidant, 3 parts of hindered phenolic antioxidant, and 1 part of thioester antioxidant.

[0050] The aforementioned phosphite antioxidant is designated as Antioxidant 168.

[0051] The hindered phenolic antioxidant is designated as Antioxidant 1010.

[0052] The brand name of the sulfur ester antioxidant is antioxidant DLTP.

[0053] The second aspect of this example provides a method for preparing an antioxidant for PC, specifically: mixing a phosphite antioxidant, a hindered phenolic antioxidant, and a thioester antioxidant evenly to obtain a compound antioxidant for PC; the product is designated as antioxidant #3.

[0054] Comparative Example 3

[0055] The first aspect of this example provides an antioxidant for PC, the raw materials for which are prepared by mass parts are: 6 parts of phosphite antioxidant, 3 parts of hindered amine antioxidant, and 1 part of thioester antioxidant.

[0056] The aforementioned phosphite antioxidant is designated as Antioxidant 168.

[0057] The hindered amine antioxidant is designated as Antioxidant 944.

[0058] The brand name of the sulfur ester antioxidant is antioxidant DLTP.

[0059] The second aspect of this example provides a method for preparing an antioxidant for PC, specifically: mixing a phosphite antioxidant, a hindered amine antioxidant, and a thioester antioxidant evenly to obtain a compound antioxidant for PC; the product is designated as antioxidant #4.

[0060] Comparative Example 4

[0061] This example provides an antioxidant for PC, specifically prepared by mass fraction of 10 parts of phosphite antioxidant, which is antioxidant 168; the product is designated as antioxidant #5.

[0062] Comparative Example 5

[0063] This example provides an antioxidant for PC, specifically prepared by mass fraction of 10 parts of a thioester antioxidant, which is DLTP antioxidant; the product is designated as antioxidant #6.

[0064] Unless otherwise specified, all raw materials used in Example 1 and Comparative Examples 1-5 above are commercially available products.

[0065] Comparative Example 6

[0066] The first aspect of this example provides a long-lasting, aging-resistant compound antioxidant for PC, which is prepared by the following raw materials in parts by mass: 3 parts phosphite antioxidant, 5 parts hindered amine antioxidant, 1 part thioester antioxidant, and 1 light stabilizer.

[0067] The aforementioned phosphite antioxidant is designated as Antioxidant 168.

[0068] The hindered amine antioxidant is designated as Antioxidant 944.

[0069] The brand name of the sulfur ester antioxidant is antioxidant DLTP.

[0070] The light stabilizer is designated as Tinuvin 531.

[0071] The second aspect of this example provides a method for preparing a long-lasting and aging-resistant compound antioxidant for PC, specifically: mixing a phosphite antioxidant, a hindered amine antioxidant, a thioester antioxidant, and a light stabilizer evenly to obtain a compound antioxidant for PC; the product is designated as Antioxidant No. 8.

[0072] Performance Evaluation

[0073] 1. Test Object

[0074] Antioxidant #1 and PC material are mixed evenly at a mass ratio of 0.1:100 to obtain PC processing material #1.

[0075] Antioxidant #2 and PC material are mixed evenly at a mass ratio of 0.1:100 to obtain PC processing material #2.

[0076] Antioxidant #3 and PC material are mixed evenly at a mass ratio of 0.06:100 to obtain PC processing material #3.

[0077] Antioxidant #4 and PC material are mixed evenly at a mass ratio of 0.06:100 to obtain PC processing material #4.

[0078] Antioxidant #5 and PC material are mixed evenly at a mass ratio of 0.06:100 to obtain PC processing material #5.

[0079] Antioxidant #6 and PC material are mixed evenly at a mass ratio of 0.06:100 to obtain PC processing material #6.

[0080] The control group consisted of blank PC material (pure polycarbonate) without antioxidants, denoted as 7# PC processed material.

[0081] Antioxidant #8 and PC material are mixed evenly at a mass ratio of 0.1:100 to obtain PC processing material #8.

[0082] 2. High-temperature aging resistance test

[0083] The 1-8# PC processing material was added to a twin-screw extruder (L / D=42) and extruded once at 280℃ and 60rpm. Then, the 1-8# PC processing material was extruded twice at 300℃ and 60rpm. The YI (yellowing index) value of the products was sampled and tested. The experimental results are detailed in Table 1.

[0084] Table 1

[0085] As can be seen from the experimental results in Table 1, the use of antioxidant #1 in Example 1 of this invention can effectively improve the high-temperature aging resistance of PC during processing. The YI values ​​of the products extruded at 280℃ and 300℃ are both low, and it has better high-temperature aging resistance than antioxidants #2-6 and #8.

[0086] 3. Long-term aging resistance test

[0087] The 1-8# PC processing material was added to a twin-screw extruder (L / D=42) and extruded once at 280℃ and 60rpm. Then, the 1-8# PC processing material was extruded twice at 300℃ and 60rpm. The resulting product was then aged at 80℃ for 15 days. Samples were taken to test the YI (yellowing index) value of the product. The experimental results are detailed in Table 2.

[0088] Table 2

[0089] As can be seen from the experimental results in Table 1, the use of antioxidant #1 in Example 1 of this invention can effectively reduce the YI value of PC processed materials after aging at 80°C for 15 days, and has better long-term aging resistance than antioxidants #2-6 and #8.

Claims

1. A long-lasting, aging-resistant compound antioxidant for PC, characterized in that, The raw materials for preparation include antioxidants and light stabilizers; The antioxidants mentioned include at least three of the following: hindered phenolic antioxidants, phosphite antioxidants, hindered amine antioxidants, and thioester antioxidants.

2. The long-lasting, aging-resistant compound antioxidant for PC according to claim 1, characterized in that, The hindered phenolic antioxidants include one or more of the following: antioxidant 1010, antioxidant 1076, antioxidant 2246, or antioxidant BHT.

3. The long-lasting, aging-resistant compound antioxidant for PC according to claim 1, characterized in that, The phosphite antioxidants mentioned include monophosphite antioxidants or diphosphite antioxidants.

4. The long-lasting, aging-resistant compound antioxidant for PC according to claim 3, characterized in that, The grades of the monophosphite antioxidants include antioxidant 168 or antioxidant TPP.

5. The long-lasting, aging-resistant compound antioxidant for PC according to claim 3, characterized in that, The grades of the bisphosphite antioxidants include one or more of antioxidant 626, antioxidant 618, antioxidant P-EPQ, or antioxidant AS-4500.

6. The long-lasting, aging-resistant compound antioxidant for PC according to claim 1, characterized in that, The hindered amine antioxidants include one or more of the following grades: antioxidant 944, antioxidant 770, antioxidant 711, antioxidant 622, antioxidant 783, antioxidant 292, antioxidant 123, or antioxidant 2020.

7. The long-lasting, aging-resistant compound antioxidant for PC according to claim 1, characterized in that, The grades of the sulfur ester antioxidants include one or more of antioxidant 636, antioxidant 412S, antioxidant DLTP, antioxidant DSTDP, or antioxidant DMTDP.

8. The long-lasting, aging-resistant compound antioxidant for PC according to any one of claims 1-7, characterized in that, The light stabilizer includes one or more of benzotriazole light stabilizers, triazine light stabilizers, hindered amine light stabilizers, or benzophenone light stabilizers.

9. The long-lasting, aging-resistant compound antioxidant for PC according to claim 1, characterized in that, The raw materials for preparing the compound antioxidant for PC include phosphite antioxidants, hindered amine antioxidants, thioester antioxidants, and light stabilizers; The mass ratio of the phosphite antioxidant, hindered amine antioxidant, thioester antioxidant and light stabilizer is (5-8):(1-3):(1-2):(1-2).

10. A method for preparing a long-lasting, aging-resistant compound antioxidant for PC according to any one of claims 1-9, characterized in that, include: The antioxidant and light stabilizer are mixed evenly to obtain a long-lasting and aging-resistant compound antioxidant for PC.

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