Steric hindrance adjustable weak base light stabilizer and preparation method and application thereof

Abstract

The present invention is a divisional application of the Chinese invention patent application with application number 202011250638.2 and invention name “Structure of sterically hindrance adjustable weakly alkaline light stabilizer, preparation method and application thereof”. The present invention patent belongs to the field of new compounds and their synthesis methods, and specifically relates to sterically hindrance adjustable weakly alkaline light stabilizers, preparation methods and applications thereof. The innovative light stabilizer of the present invention adjusts its steric hindrance by establishing the size of the substituents that produce steric hindrance around the nitrogen atom in the general structural formula. In addition, the electronegativity of the nitrogen atom can be affected by adjusting the distance of the polar group, thereby adjusting its alkalinity or nucleophilicity. The desired effect is obtained by regulating the steric hindrance and nucleophilicity or alkalinity of the environment in which the nitrogen atom is located, thereby broadening the scope of application of this type of innovative light stabilizer, making it widely applicable to PC, polyester, PU, ​​PVC and other polymer materials that are acidic or have certain electrophilic properties as light stability protection aids.

Description

[0001] This invention is a divisional application of the Chinese invention patent application with application number 202011250638.2, application date November 11, 2020, and invention name “Structure of sterically adjustable weak base light stabilizer, preparation method and application thereof”. Technical Field

[0002] The patent of this invention belongs to the field of new compounds and their synthesis methods, and specifically relates to sterically tunable weak base light stabilizers and their preparation methods and applications. Background Art

[0003] Polymer materials play an increasingly important role in today's developed world, from simple molding of different industrial disposable products to high-tech components used in space. Such diverse and complex applications require that the different physical and chemical properties of polymer materials must meet the requirements of the diversity required by specific applications. Therefore, polymer materials have become more and more complex. They are not only composed of various basic polymers, but also require the addition of a large number of various additives including different functional additives. These functional additives play a decisive role in giving polymer materials the required unique properties. Among polymer additives, light stabilizers and antioxidant stabilizers are the most important ones. The antioxidant function is to effectively provide polymers to resist degradation caused by heat, other environmental oxidizing factors and ultraviolet light during processing and use. This is of particular significance to polymer materials. The quality of polymer antioxidant stabilizers can directly predict the service life of products and avoid the critical negative impact caused by product failure.

[0004] Light stabilizers are becoming more and more important in the use of polymer materials. They provide polymer products with very effective protection against light degradation.

[0005] The light stabilizer series includes three types based on the working mechanism of protecting polymers: ultraviolet absorber (UVA), hindered amine light stabilizer (HALS), and light quencher (Quenchers). In practical applications, these three types of light stabilizers can be used alone or as a mixture, depending on the light intensity and the required protection. Light absorber UVA absorbs and filters out harmful ultraviolet rays, converting them into heat energy, electromagnetic waves and harmless long-wave light, which helps prevent the degradation of polymer materials and can also prevent discoloration and delamination of light-sensitive coatings, adhesives and sealants.

[0006] As early as the 1970s, Mitsubishi Corporation of Japan developed LS-744, 2,2,6,6-tetramethylpiperidinyl benzoate. In 1974, Ciba-Geigy of Switzerland also synthesized the same product. The protective effect of light stabilizers on polymer materials is more than 4 times that of traditional absorption types, and they have good compatibility. The annual growth rate of hindered amine light stabilizers in the world is 20%-30%, and the total consumption has accounted for 44% of the total polymer stabilizers, ranking first among all types of stabilizers. According to the third-party forecast of the global polymer stabilizer market in 2019, light stabilizers will reach a market of 790 billion US dollars in 2019 and a market of 1415.47 billion US dollars by 2027, with an annual growth rate of about 7.6%. In recent decades, as the demand for hindered amine light stabilizers continues to expand, innovative research and development has been very active, with new small molecule and oligomeric molecule products constantly emerging, but all are based on the 2,2,6,6-tetramethylpiperidinamine hindered amine core structure.

[0007] The active functional group structure of hindered amine light stabilizer is as follows:

[0008]

[0009] In the above tetramethylpiperidinamine hindered amine core active functional group general structure, the hindered amine light stabilizer widely used in the market is structure-A type light stabilizer with the lowest cost. Common hindered amine light stabilizers on the market include cyasorb3853, Hostavin 3050, Hostavin TM N 20, Tinuvin 770, Hostavin 3052, Hostavin 3058, Hostavin 3055, Uvinul 4050H, Chimassorb 2020, Uvasorb HA 88, Chimassorb 944, etc.

[0010] However, this type of tetramethylpiperidinium hindered amine core structure hindered amine light stabilizer cannot be used in polymers such as PVC, PC, PU, ​​and polyesters. The main reason is that the N atom in the hindered amine core of tetramethylpiperidinamine exhibits relatively strong alkalinity and nucleophilicity. During processing and use, the nucleophilic nitrogen atom is easy to react with electrophilic or acidic functional groups on the polymer, thereby catalyzing and accelerating the degradation of acidic polymer materials.

[0011] Reducing the basicity or nucleophilicity of the tetramethylpiperidinamine HALS nucleus is the only way to broaden the application range of hindered amine light stabilizers. So far, there are two methods to reduce the basicity of nitrogen atoms in tetramethylpiperidinamine hindered amine HALS: (1) alkylation on the NH bond of piperidineamine to form an NR bond, which increases the steric hindrance effect around the nitrogen atom in piperidineamine, thereby achieving the purpose of reducing the basicity of piperidineamine; (2) introducing an alkoxy group to the NH bond of piperidineamine to form an N-OR bond, so that the nitrogen atom in piperidineamine reduces the basicity from the dual effects of reduced electronegativity and increased steric hindrance effect around the nitrogen atom.

[0012] Hindered amine HALS light stabilizer is a type of free radical scavenger. Its mechanism of action is very complex. It achieves light protection effect mainly through the synergistic effect of the following mechanisms: (1) capturing free radicals; (2) decomposing hydroperoxides; (3) capturing heavy metals.

[0013] The hindered amine light stabilizers with structure-B and structure-C parent core tetramethylpiperidinamine type are called weak alkaline light stabilizers. Such N-OR type light stabilizer products, such as Chimassorb 119, Tinuvin 144, Tinuvin 292, Tinuvin 152, Tinuvin 371, Flamestab 116, Tinuvin 622, Cyasorb 3529, have been used in the market.

[0014] As shown above, the structures of weak base hindered amines are more complicated than those of conventional hindered amines. In fact, both small molecule weak base hindered amine light stabilizers and oligomeric weak base hindered amine light stabilizers require additional synthesis steps to obtain these products compared with conventional hindered amines. Therefore, the cost price will be more expensive, and the additional chemical synthesis will also bring greater pressure to green environmental protection. Summary of the invention

[0015] The patent of this invention reports for the first time an innovative structural light stabilizer with adjustable steric hindrance and controllable weak base properties of nitrogen atoms and without 2,2,6,6-tetramethylpiperidinamine structural fragments.

[0016] The general formula of the innovative small molecule light stabilizer is as follows:

[0017]

[0018] Wherein, X is NH, NR3, O;

[0019] Y is H, methyl, ethyl or other alkyl;

[0020] R is -(CH2)n-, wherein n=2-22, or -(CH2) substituted by an alkyl or aromatic side chainn -, or dibenzylamine;

[0021] R1 and R2 are alkyl, or i-Pr, i-Bu, isopentyl, isooctyl, cyclohexyl, substituted cyclohexyl, cyclopentyl, benzyl, substituted benzyl, allyl, substituted allyl, alkyl containing double bonds, alkyl containing aromatic substitutions, R1 and R2 together are

[0022] R1 and R2 are the same or different; when R1 and R2 are different, R1 = Et, i-Pr, n-Pr, Bu, i-Bu, or C5-12 alkyl;

[0023] R2= Or hydroxyethyl or hydroxypropyl.

[0024] Specifically, the innovative small molecule light stabilizer structure of the present invention includes:

[0025]

[0026] The preparation method of the above-mentioned sterically hindrance adjustable weak base light stabilizer has the following reaction formula:

[0027]

[0028] The preparation steps include:

[0029] (1) Add methyl acrylate or methyl methacrylate to a reaction flask under nitrogen protection, start stirring, then add 1-3 parts of an organic solvent or no solvent, then add 0.01-30% of catalyst 1, lower the temperature to 5-20° C., and then slowly dropwise add the second amine; after the dropwise addition is completed, heat to room temperature and stir for 5-24 hours. If the reaction needs to be continued, heat to 40-80° C. and continue the reaction for 5-18 hours; monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and use the remaining reaction intermediate for the next step without further purification;

[0030] (2) Under nitrogen protection and stirring, alkyl diamine, ethylene diamine, butyl diamine, hexamethylene diamine or decanediamine are first added in batches to the intermediate obtained in the first step at room temperature, and then 0.1-5% of catalyst 2 is added. After the addition is completed, the temperature is raised to 50-70° C. and the reaction is carried out for 6-16 hours, and the temperature is further raised to 85-120° C. and the reaction is carried out for 48-96 hours. The reaction progress is monitored by TLC until the reaction is complete; the catalyst is removed, a recrystallization solvent is added for recrystallization, and the product is filtered and dried to obtain a white powder solid product.

[0031] Furthermore, the organic solvent in step (1) includes methanol, ethanol, ethyl acetate, dichloroethane, acetone, acetonitrile or DMF.

[0032] Furthermore, the catalyst 1 in step (1) is acetic acid, acidic alumina, silica gel, o-methoxyhydroquinone, 4,4-diphenolic hydroxybenzophenone or m-nitrophenol.

[0033] Furthermore, the catalyst 2 in step (2) is sodium methoxide, sodium formate, diethyltin oxide or aluminum isooctoxide.

[0034] Furthermore, the recrystallization solvent in step (2) is 0.5-20% aqueous ethanol, methanol, ethyl acetate or petroleum ether.

[0035] The invention also discloses the application of the sterically hindrance adjustable weakly alkaline light stabilizer in the field of polymer materials to provide light stability protection and anti-oxidation stability protection.

[0036] Compared with the widely used hindered amine (HALS) light stabilizer products on the market, the sterically hindrance adjustable weak base light stabilizer product designed and invented by the present invention has a more superior steric hindrance adjustable function, and the weak base property broadens the application range. Although they can provide different degrees of weather resistance protection for polymer materials, from the perspective of chemical functional group structure, hindered amine (HALS) is a type of light stabilizer that has been used for about half a century. Its structural characteristics are: each hindered amine light stabilizer product molecular structure contains 2,2,6,6-tetramethylpiperidinamine functional group structure This hindered amine functional structure can quickly transfer the active free radicals produced by light-induced degradation on the polymer, thus playing an important role in weather protection for the polymer material and also having a certain antioxidant effect.

[0037] The hindered amine HALS light stabilizer, which has been widely used for about half a century, is limited in its application in some polymer materials due to its specific chemical structure, tetramethyl piperidine amine, which has a partial alkalinity and nucleophilicity defined by its structure. For example, PVC, PC, polyester, PU, ​​etc., the nucleophilic or alkaline nitrogen atom of tetramethyl piperidine amine will react with these polymer materials with certain acidic or electrophilic properties, thereby playing a role in degrading these polymer materials. The following reaction equation shows the mechanism of how hindered amine HALS participates in the degradation of PVC polymer materials.

[0038]

[0039] In order to weaken the nucleophilicity or basicity of hindered amine light stabilizers, there are usually two methods to modify the nitrogen atom of the hindered amine: (1) introducing a methyl or alkyl group on the nitrogen atom of tetramethylpiperidinamine to increase the steric hindrance around the piperidineamine, thereby weakening its basicity or nucleophilicity; (2) introducing an alkoxy group on the nitrogen atom of tetramethylpiperidinamine, which can both reduce the electronegativity of the piperidineamine nitrogen atom and increase the steric hindrance around the nitrogen atom, thereby reducing the basicity and nucleophilicity.

[0040] Whether increasing steric hindrance by introducing alkyl groups to reduce alkalinity or nucleophilic attacking ability, or introducing alkoxy groups to reduce the electronegativity of nitrogen atoms and increasing steric hindrance to reduce their alkalinity or nucleophilic attacking ability, 1-3 steps of additional chemical reactions are required, especially oxidation, reduction or alkylation reactions. These chemical reactions not only add additional burden to environmental protection, but also increase additional product costs. Therefore, the market price of weakly basic hindered amine products is particularly high compared with ordinary hindered amine products.

[0041] The innovative photostable structure of the present invention avoids the continued use of 2,2,6,6-tetramethylpiperidinamine functional structure fragments, and designs the steric hindrance of the substituents around the nitrogen atom and the polarity control of the functional group from a completely different new perspective. By adjusting the size of the substituents around the nitrogen atom, the size of the steric hindrance around the nitrogen atom is adjustable and controllable. In this way, the hindered amine compounds with reduced alkalinity can be provided by controlling the steric hindrance characteristics around the nitrogen atom, thereby making it suitable for various polymer material photodegradation protection applications with certain electrophilic properties. In addition, the raw materials of the present invention are easy to obtain, and the designed green synthesis process greatly simplifies the synthesis steps, reduces the three synthetic wastes generated, and reduces the synthesis cost. In addition, the innovatively designed structure of the present invention provides new opportunities for the selection of polymer material light stabilizers.

[0042] The innovative light stabilizer of the present invention adjusts its steric hindrance by establishing the size of the substituents that generate steric hindrance around the nitrogen atom in the above general structural formula. In addition, the electronegativity of the nitrogen atom can be affected by adjusting the distance of the polar group, thereby adjusting its alkalinity or nucleophilicity. The desired effect is obtained by regulating the steric hindrance and nucleophilicity or alkalinity in the environment of the nitrogen atom, thereby broadening the application scope of this type of innovative light stabilizer, making it suitable for use as a light stability protection agent for acidic or electrophilic polymer materials such as PC, polyester, and PVC.

[0043] In addition, the raw materials of the product disclosed in the present invention are easily available, a green and environmentally friendly synthesis process is adopted, and less three wastes are generated, thus providing the best conditions for promotion and application.

[0044] The purpose of the present invention is to design and synthesize a sterically hindrance adjustable weak alkaline light stabilizer, which solves the defect that hindered light stabilizers (HALS) are difficult to be applied to acidic or electrophilic polymers as light stability protection agents; at the same time, due to the adjustable performance of the side chain of the structural substituent and the polarity of other polar functional groups in the molecule, the compatibility of the HALS with the high molecular polymer is increased; in addition, the innovative light stabilizer designed by the present invention breaks the nearly half-century monopoly of the fixed structure of 2,2,6,6-tetramethylpiperidinamine as the active functional group of the light stabilizer, and its characteristic structure cannot be avoided in chemical synthesis, especially the additional chemical synthesis step of converting the conventional hindered amine structure into a weak alkaline hindered amine light stabilizer is inevitable, which makes the cost and the environment present an unimprovable state.

[0045] The sterically hindrance adjustable weak-base light stabilizer of the present invention has readily available raw materials and can be synthesized into the desired product through a green and environmentally friendly process, which greatly facilitates its production and wide application, making it possible to become a valuable light stability protection auxiliary agent for all polymer materials (including PVC, PC, PU, ​​polyester, etc.).

[0046] The patent of this invention reports for the first time an innovative structural light stabilizer with adjustable steric hindrance and controllable weak base properties of nitrogen atoms and without 2,2,6,6-tetramethylpiperidinamine structural fragments.

[0047] The patented innovative chemical structure product of this invention can be directly applied to polymer materials to provide effective light stability protection and antioxidant stability protection, and can play a role in long-term preservation, color retention, and function maintenance of polymer material products during use. It can be applied to plastics, rubber, fiber, film, coating, paint, ink, petroleum and other product series, and its market is very broad.

[0048] The present invention aims to:

[0049] (1) Design and synthesize sterically tunable weakly alkaline or near-neutral light stabilizers, and make them applicable to all polymer materials (including PVC, PC, PU, ​​polyester, etc.), providing more extensive and valuable light stability protection.

[0050] (2) Providing more photostable functional group structures, breaking the long-standing situation in the international market where 2,2,6,6-tetramethylpiperidinamine is the only photostable functional group.

[0051] (3) Provide the market with a more simplified synthesis method for green and environmentally friendly light stabilizers.

[0052] Compared with the prior art, the present invention solves the following problems:

[0053] (1) Solved and changed the status of 2,2,6,6-tetramethylpiperidinamine, a sterically hindered light stabilizer, as the only choice ever.

[0054] (2) The structure of the newly designed light stabilizer can be adjusted according to the required steric hindrance and the basicity and nucleophilicity of the light stabilizer, which broadens the application range of light stabilizers in polymer materials.

[0055] (3) The designed weak alkaline and weak nucleophilic innovative structured light stabilizers provide new opportunities for polymer materials such as PVC, PC, polyester, PU, ​​etc. that cannot currently use tetramethylpiperidinamine hindered amine light stabilizers, providing these polymer materials with a better choice of UV protection agents.

[0056] (4) The problem of incompatibility between 2,2,6,6-tetramethylpiperidinamine alkaline light stabilizers and acidic additives was solved.

[0057] (5) We have broken through the complicated synthesis methods of weak-base photostabilizers on the market and synthesized new photostabilizers using an optimized, simple and green synthesis method.

[0058] (6) The sterically tunable weakly alkaline light stabilizer of the present invention exhibits better compatibility with polymer materials, thereby improving the heat aging and yellowing resistance and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Comparison of heat and light aging results of PP-T20 strips (Note: (1) The strips in the upper row are the results of heat aging in an oven at 150°C for 192 hours, and the strips in the lower row are the results of UVB aging at 70°C for 157 hours; (2) Test comparison standards: B1 is 3853, B2 is 770, and B3 is 622; (3) B4-B13 are the innovative antioxidants and air barrier adjustable light stabilizers of the present invention).

[0060] Figure 2 Comparison of the results of heat and light aging of ABS specimens (Note: (1) The upper row of specimens are the results of 178 hours of heat aging in an oven at 110°C, and the lower row of specimens are the results of 113 hours of UVB light aging at 70°C; (2) Test comparison standards: C1 is 3853, C2 is 770, and C3 is 622; (3) C4-C12 are Ruikang’s innovative antioxidants and air barrier adjustable light stabilizers).

[0061] Figure 3 PC sample UVB aging at 70°C for 47 hours result 1 (antioxidant AO + light stabilizer (2:1): 0.1%; UV aging test equipment is Q-Lab).

[0062] Figure 4PC sample UVB aging test results at 70℃ / 17 hours 2 ((1) The upper row of samples are the results of 17 hours of heat aging in a 150℃ oven, and the lower row of samples are the results of 48 hours of UVB light aging at 70℃; (2) Test comparison standards: C3 is 622, C5 is 2020; (3) C1, C2, and C4 are Ruikang’s innovative antioxidants and air-barrier adjustable light stabilizers; (4) The UVB light aging test equipment is Q-Lab UV light aging tester Suzhou Guangjun ZN-PB).

[0063] Figure 5 PC sample aging results under UVB light at 70°C 3 (Note: (1) The PC samples in the lower row are PC samples before aging; (2) The upper row are samples aged under UVB light at 70°C for 24 hours (3) Comparison standard samples: UV2020 (#3) and UV119 (#1)). DETAILED DESCRIPTION

[0064] Table 1: Example of innovative weak-base photostabilizer with adjustable air resistance Structure Mass spectrometer: Thermo Finnigan LCQAdvantage Thermo Fisher Scientific NMR equipment: Avance III 400MHz Bruker, Switzerland

[0065]

[0066]

[0067]

[0068]

[0069]

[0070] The chemical structural formula of the organic compound in Table 1 includes the example structure represented by the general structural formula of the innovative light stabilizer listed above in the present invention. The synthesis method thereof adopts a solvent-free green chemical synthesis method, and the catalyst reduces the activation energy of the reaction, so that the synthesis of the target product is successfully completed.

[0071] (1) Innovative synthesis route of light stabilizer:

[0072]

[0073] (2) General synthesis method

[0074] 1. Add methyl acrylate or methyl methacrylate (2.5-4.5mmol) to the reaction bottle under nitrogen protection, start stirring, then add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 0.01-30% of catalyst 1 (catalyst 1 is: acetic acid, acidic alumina, silica gel, o-methoxy hydroquinone, 4,4-diphenol hydroxy diphenyl ketone, m-nitrophenol), lower the temperature to 5-20°C, and then slowly add the second amine (1.90-2.05mmol). After the addition is complete, heat to room temperature and stir for 5-24 hours. If the reaction needs to be continued, continue to heat to 40-80°C and continue the reaction for 5-18 hours. Monitor the reaction progress by TLC until the reaction is complete, remove the excess methyl acrylate under vacuum, and the remaining reaction intermediate is used for the next step without further purification.

[0075] 2. Under nitrogen protection and stirring, add alkyl diamines such as ethylenediamine or butylene diamine or hexamethylenediamine or decanediamine (1.0-1.2mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1-5% catalyst 2 (catalyst 2 can be sodium methoxide, sodium formate, diethyltin oxide, aluminum isooctoxide, etc.), heat to 50-70°C after the addition is completed, react for 6-16 hours, continue to heat to 85-120°C, react for 48-96 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 0.5-20% aqueous ethanol or methanol or ethyl acetate or petroleum ether for recrystallization, filter to give a white powder solid product, dry, and the yield is 85-95%.

[0076] (3) Synthesis method of product example of general structure 3

[0077] Synthesis method of example structure A:

[0078]

[0079] 1. Add methyl acrylate (2.2-3.5mmol) to the reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 30% silica gel (400 mesh), lower the temperature to 15-20℃, and then slowly drop 3-methylpiperidinamine (1.95-2.01mmol). After the addition is complete, heat to room temperature and stir for 5-7 hours, continue to heat to 40-50℃ and continue to react for 5-10 hours. Monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and the remaining reaction intermediate is used for the next step without further purification.

[0080] 2. Under nitrogen protection and stirring, add hexamethylenediamine (1.0-1.05mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate, and after the addition, heat to 50-60°C for reaction for 10-15 hours, continue to heat to 85-120°C for reaction for 48-96 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 0.5-5% aqueous methanol or ethyl acetate or petroleum ether for recrystallization, filter to give a white powder solid product, dry, and the yield is 83.9%.

[0081] Synthesis method of example structure B:

[0082]

[0083] 1. Add methyl acrylate (2.5-4.5mmol) to the reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 100-600ppm of 4,4'-diphenol hydroxybenzophenone or o-methoxy hydroquinone or m-nitrophenol, lower the temperature to 20℃, and then slowly drop dibenzylamine (1.96-2.03mmol). After the addition is complete, stir at room temperature for 5 hours, raise the temperature to 40-60℃ and continue the reaction for 10-32 hours. Monitor the reaction progress by TLC until the reaction is complete, remove the excess methyl acrylate under vacuum, and the remaining reaction intermediate is used for the next step without further purification.

[0084] 2. Under nitrogen protection and stirring, add hexamethylenediamine (1.05-1.15mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate or no catalyst, and after the addition, heat to 50-70°C for reaction for 8-10 hours, continue to heat to 80-125°C for reaction for 32-72 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 5% aqueous ethanol or ethyl acetate or petroleum ether for recrystallization, filter to give a white powder solid product, dry, and the yield is 90.3%.

[0085] The synthesis method of example structure C:

[0086]

[0087] 1. Add methyl acrylate (2.5-3.8mmol) to the reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 200-700ppm of 4,4'-diphenol hydroxybenzophenone or o-methoxy hydroquinone or m-nitrophenol, and then slowly add dibenzylamine (1.96-2.03mmol) at room temperature. After the addition is complete, stir at room temperature for 18 hours, and if necessary, heat to 40-60℃ and continue the reaction for 5-15 hours. Monitor the reaction progress by TLC until the reaction is complete, remove the excess methyl acrylate under vacuum, and the remaining reaction intermediate is used for the next step without further purification.

[0088] 2. Under nitrogen protection and stirring, add hexamethylenediamine (1.05-1.15mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate or no catalyst, and after the addition, heat to 50-70°C for reaction for 6-8 hours, continue to heat to 80-125°C for reaction for 48-72 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 5% aqueous ethanol or ethyl acetate or petroleum ether for recrystallization, filter to give a white powder solid product, dry, and the yield is 92.6%.

[0089] The synthesis method of example structure D is:

[0090]

[0091] 1. Add methyl acrylate (2.80-4.8mmol) to the reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 200-700ppm of 4,4'-diphenol hydroxybenzophenone or o-methoxy hydroquinone or m-nitrophenol, and then slowly add diisopropylamine (1.95-2.01mmol) at room temperature. After the addition is complete, stir at room temperature for 18 hours, heat to 50-60℃ and continue to react for 18-32 hours. Monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and use the remaining reaction intermediates for the next step without further purification.

[0092] 2. Under nitrogen protection and stirring, add hexamethylenediamine (1.05-1.15mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate or no catalyst, after the addition is completed, heat to 60-70°C for reaction for 8-10 hours, continue to heat to 80-125°C for reaction for 48-72 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 0.5% ethyl acetate or petroleum ether containing water for recrystallization, filter to give a white powder solid product, dry, and the yield is 86%.

[0093] The synthesis method of example structure E:

[0094]

[0095] 1. Add methyl acrylate (2.8-3.8mmol) to a reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 20% acidic alumina, and then slowly add di(2-hydroxyethyl)amine (1.97-2.0mmol) dropwise at room temperature. After the addition is complete, stir at room temperature for 5 hours, heat to 35-60°C and continue to react for 15-24 hours. Monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and the remaining reaction intermediate is used for the next step without further purification.

[0096] 2. Under nitrogen protection and stirring, add hexamethylenediamine (1.0-1.1mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate or no catalyst, raise the temperature to 50-70°C after the addition is completed, react for 6-8 hours, continue to raise the temperature to 80-125°C for 48-72 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 5-10% aqueous ethanol or methanol for recrystallization, filter to give a colorless oily liquid product, dry, and the yield is 95.6%.

[0097] The synthesis method of example structure F:

[0098]

[0099] 1. Add methyl acrylate (2.6-3.5mmol) to the reaction bottle under nitrogen protection, start stirring, add 1-3 parts of methanol or ethanol or ethyl acetate or dichloroethane or acetone or acetonitrile or DMF or no solvent, then add 4,4-diphenol hydroxybenzophenone or o-methoxy hydroquinone or no catalyst. Slowly add diisobutylamine (1.98-2.0mmol) dropwise at room temperature. After the addition is complete, stir at room temperature for 5 hours, heat to 30-60℃ and continue to react for 15-24 hours. Monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and use the remaining reaction intermediates for the next step without further purification.

[0100] 2. Under nitrogen protection and stirring, add hexamethylenediamine (0.95-1.1mmol) in batches to the intermediate obtained in the first step at room temperature, then add 0.1% sodium methoxide or sodium formate or no catalyst, and after the addition, heat to 50-70°C for reaction for 6-8 hours, continue to heat to 80-120°C for reaction for 48-72 hours, and track the reaction progress by TLC until the reaction is complete. Remove the catalyst, add 5-15% aqueous ethanol or methanol for recrystallization, filter to give a white powder solid product, dry, and the yield is 93.5%.

[0101] The innovative light stabilizer of the present invention was tested for heat aging performance in different polymer materials and for aging performance under UVB and 300W ultraviolet light, as well as for parallel comparative tests with commonly used brands of light stabilizers in the international market. These tests were completed in PP, ABS, and PC polymer materials respectively.

[0102] (1) Comparative test of thermal aging and ultraviolet aging performance of the sterically tunable weakly alkaline light stabilizer of the present invention in PP-T20

[0103] a. Twin screw extrusion granulation

[0104] Granulation is done by extrusion granulation using a twin-screw extruder (Nanjing Keya AK36):

[0105] Extruder parameters:

[0106] Temperature of zones 1 to 10 (°C): 160, 190, 210, 220, 220, 220, 210, 210, 210, 200

[0107] Speed: 300rpm

[0108] Table 2: PP-T20 formula

[0109]

[0110]

[0111] Main antibody B215: 0.2%; (See brand Figure 1 )

[0112] Light stabilizer: 0.1% (see brand Figure 1 )

[0113] b. Preparation of PP-T20 specimens

[0114] The PP-T20 strips were produced using Haitian SA1200 injection molding machine.

[0115] Injection molding machine processing parameters:

[0116] Temperatures from 1 to 5 (°C): 200, 210, 210, 205, 190;

[0117] Injection pressure: 58 bar

[0118] c.150℃ oven thermal aging test

[0119] Oven heat aging is carried out in a heat aging oven in accordance with GB / T 7141-2008 Plastics Heat Aging Test Method.

[0120] d.UVB photoaging test

[0121] UVB light aging test was completed in a UVB light aging test chamber (Q-Lab Suzhou Guangjun) in accordance with GB / T 16422.1-2006 Plastics Laboratory Light Source Exposure Test Method Part 1 General Principles and GB / T16422.3-2014 Plastics Laboratory Light Source Exposure Test Method Part 3 Fluorescent Ultraviolet Lamp Principles.

[0122] e.150℃ oven heat aging and UVB ultraviolet aging test results ( Figure 1 )

[0123] f. Results and Discussion

[0124] From the results of PP-T20 specimens heat aging in an oven at 150°C, the comparison test of international market products B1 (3853), B2 (770) and B3 (622) are obviously darker than the specimens (B4-B13) with the product of the present invention, among which the specimen (B2) with the light stabilizer 770 has the darkest color, the specimen with the light stabilizer 622 has a lighter color, and the specimen (B1) with the light stabilizer 3853 has the lightest color among the three international companies' products. In contrast, the specimens (B4-B13) with the light stabilizer of the present invention are lighter in color than the specimens with the light stabilizer of the international market.

[0125] From the VUB UV aging test results, B7 and B13 are the lightest in color, B8 and B12 are similar in whiteness to the 3853 (B1), 770 (B2), and 622 (B3) samples, and B4, B5, and B6 are darker in color.

[0126] The sterically hindrance-adjustable weakly alkaline light stabilizer of the present invention has better compatibility with polymer materials, so it can not only provide better light stability protection, but also have better heat aging protection and anti-yellowing performance.

[0127] Mechanical properties test results:

[0128] Table 3: Comparative test of tensile properties of Ruikang innovative light stabilizer in PP-T20 (comparison samples: 3853, 770, 622) Batch number: PPT20 RK-PT-T20201014

[0129]

[0130]

[0131]

[0132] Test conditions:

[0133] Laboratory environment: temperature 23°C, humidity 45% RH; state adjustment: 23°C, 50% RH;

[0134] Implementation standard: GB / T1040.2-2006 / ISO 527-2:1993;

[0135] Stretching speed: 50mm / min

[0136] Note: The light stabilizer with the last digit of the RK brand followed by the letter L is a liquid antioxidant.

[0137] From the comprehensive mechanical tensile data: the mechanical tensile performance test results of the present invention in Table 1 are compared with the market products of major international companies. Some brands show outstanding performance in maintaining mechanical properties.

[0138] (a) From the comparison results of tensile strength before and after heat and light aging with the best market light stabilizers 3853, 770, and 622 in PP, some brands of light stabilizers of the present invention show smaller changes in physical properties in parallel aging tests. For example, the tensile strength retention rates of RK-AB75S, RK-AB-76S, RK-AB77, RK-ABUV721, and RK-AB71L all show extremely good tensile strength retention rates after 288 hours of heat aging and 207 hours of light aging. From the data, there is no obvious aging effect, and the tensile strength retention rate basically has no obvious change. From the results of heat aging, the retention rate is better than that of the reference standard.

[0139] (b) From the perspective of modulus before and after aging and tensile elongation, the light stabilizer product of the present invention presents slightly better results.

[0140] (2) Comparative test of thermal aging and ultraviolet aging performance of the sterically tunable light stabilizer of the present invention in ABS

[0141] a. Twin screw extrusion granulation

[0142] Granulation is done by extrusion granulation using a twin-screw extruder (Nanjing Keya AK36):

[0143] Extruder parameters:

[0144] Temperature of zones 1 to 10: 200, 205, 215, 215, 215, 215, 210, 210, 205, 200

[0145] Rotation speed: 300m / s

[0146] Main resistance: 0.2%; Light stabilizer: 0.1%

[0147] Standard comparison samples: C1 spline: 3808, C2 spline 770, C3 spline: 622.

[0148] b. ABS specimen preparation

[0149] The ABS splines were made using Haitian SA1200 injection molding machine.

[0150] Injection molding machine processing parameters:

[0151] Temperatures from 1 to 5: 205, 220, 220, 215, 200;

[0152] Injection pressure: 62 bar

[0153] c. 110℃ oven heat aging test

[0154] All ABS specimens were tested in a heat aging oven at 110°C in accordance with GB / T 7141-2008 plastic heat aging test method.

[0155] d.UVB photoaging test

[0156] UVB light aging test was completed in a UVB light aging test chamber (Q-Lab Suzhou Guangjun) in accordance with GB / T 16422.1-2006 Plastics Laboratory Light Source Exposure Test Method Part 1 General Principles and GB / T16422.3-2014 Plastics Laboratory Light Source Exposure Test Method Part 3 Fluorescent Ultraviolet Lamp Principles.

[0157] e. ABS specimens at 110℃ heat aging and UVB light aging test results ( Figure 2 )

[0158] f. Results and Discussion

[0159] ABS is a resin that is sensitive to yellowing caused by light aging. According to the results of the ABS specimens tested above after 110°C oven heat aging and UVB ultraviolet aging, the specimen C7 with the innovative RK-AB79 light stabilizer of the present invention and the main resistance RK-701 has the best yellowing resistance, followed by the C4 specimen (with the innovative light stabilizer RK-AB65S of the present invention), and then the specimens C9, C8, and C5. These specimens show significantly better heat aging and yellowing resistance compared with the comparative test specimens. In summary, the sterically hindrance adjustable weak alkaline antioxidant of the present invention can still show obvious performance advantages in resisting heat yellowing and light-induced yellowing in the yellowing-sensitive ABS.

[0160] (3) Comparative test of thermal aging and UVB aging performance of the sterically tunable light stabilizer of the present invention in PC

[0161] a. Sample preparation

[0162] PC resin material: PC2805 Shanghai Covestro

[0163] PC sample preparation is completed on Haitian injection molding machine SA1200 equipment

[0164] b. PC sample processing parameters

[0165] PC sample preparation was completed on Haitian injection molding machine SA1200. Processing parameters: 1-5 temperature (℃) 266, 273, 273, 268, 265

[0166] Pressure: 90bar

[0167] Speed: 44rpm

[0168] c. PC sample aging test

[0169] (I) 150℃ oven thermal aging test results

[0170] Table 4: PC board 150℃ heat aging for 4 days (96 hours) RRK-PT-PCT20201102

[0171]

[0172]

[0173] (II) UVB aging test

[0174] PC sample UVB aging at 70℃ for 47 hours results 1( Figure 3 )

[0175] The yellowing degree of PC board after light aging is arranged from small to large as follows:

[0176] C2(PC-03)&C1(PC-02) <C3(622)<C5(PC-06)<C4(2020)

[0177] PC sample UVB aging test results at 70℃ / 17 hours 2( Figure 4 )

[0178] Table 5: PC board with light stabilizer added was aged under UVB light for 17 hours at 70°C

[0179]

[0180] PC sample aging results at 70℃ UVB 3( Figure 5 )

[0181] Table 6: PC board 150℃ heat aging for 4 days (96 hours) RRK-PT-PCT20201104

[0182]

[0183] Table 6 Data results:

[0184] Color difference: PC-10 <PC-08<PC-07<UV119<UV2020<PC-11<PC-06<PC-09

[0185] YI:13.24(PC-08)<14.31(PC-07)<14.33(PC-10)<15.23(UV119)<15.66(PC-11)<15.87(UV2020)<17.05(PC-09)<18.14(PC-06)

[0186] d. Discussion of results

[0187] Polycarbonate (PC) is the most sensitive material to light-induced yellowing. In the PC sample panels thermally aged in a 150°C oven for 4 days (96 hours) as described above (see Table 4-6), the color difference was between 1-2.6, and none exceeded 3. However, according to the test results of UVB light aging for 4 days (96 hours), the color difference was significantly increased, all between 14-16. Compared with the international brands UV119 and UV2020, the three brands of the present invention, PC-10, PC-08, and PC-07, all exhibit better resistance to light-induced yellowing. In the intuitive color comparison before and after aging of each board, it can also be seen that the color of the three brands of PC samples is lighter after light aging.

[0188] In summary, the innovative steric hindrance-adjustable structural light stabilizer of the present invention has great advantages in adjusting the structural space steric hindrance, the electronegative environment around the nitrogen atom can also be adjusted, the production process is green and easy to operate, and provides a diversified product selection for polymer weather-resistant products that can reduce costs.

Claims

1. A sterically hindrance-adjustable weakly alkaline light stabilizer, characterized in that: The general structural formula includes:

2. A method for preparing a sterically tunable weakly alkaline light stabilizer as claimed in claim 1, characterized in that: The preparation steps include: (1) Add methyl acrylate to a reaction flask under nitrogen protection, start stirring, then add an organic solvent or no solvent, then add catalyst 1, lower the temperature to 5-20° C., and then slowly dropwise add the second amine; after the dropwise addition is completed, heat to room temperature and stir for 5-24 hours, if the reaction needs to be continued to heat to 40-80° C. and continue the reaction for 5-18 hours; monitor the reaction progress by TLC until the reaction is complete, remove excess methyl acrylate under vacuum, and use the remaining reaction intermediate in the next step without further purification; (2) Under nitrogen protection and stirring, hexamethylenediamine is first added in batches to the intermediate obtained by the first step reaction at room temperature, and then catalyst 2 is added. After the addition is completed, the temperature is raised to 50-70° C. and the reaction is carried out for 6-16 hours. The temperature is further raised to 85-120° C. and the reaction is carried out for 48-96 hours. The reaction progress is monitored by TLC until the reaction is complete; the catalyst is removed, a recrystallization solvent is added for recrystallization, and the product is filtered and dried to obtain a white powder solid product.

3. The preparation method according to claim 2, characterized in that: The organic solvent in step (1) includes methanol, ethanol, ethyl acetate, ethylene dichloride, acetone, acetonitrile or DMF.

4. The preparation method according to claim 2, characterized in that: The catalyst 1 in step (1) is acetic acid, acidic alumina, silica gel, o-methoxyhydroquinone, 4,4-diphenolic hydroxybenzophenone or m-nitrophenol.

5. The preparation method according to claim 2, characterized in that: The catalyst 2 in step (2) is sodium methoxide, sodium formate, diethyltin oxide or aluminum isooctoxide.

6. The preparation method according to claim 2, characterized in that: The recrystallization solvent in step (2) is 0.5-20% aqueous ethanol, methanol, ethyl acetate or petroleum ether.

7. A use of the sterically tunable weakly alkaline light stabilizer as claimed in claim 1 to provide light stability protection and anti-oxidation stability protection in the field of polymer materials.

Images