A modifier for improving the hardness of PC resin and a preparation method of modified PC resin

Abstract

This invention relates to the field of polymer materials technology, specifically to a modifier for improving the hardness of PC resin and a method for preparing the modified PC resin. The method for preparing the modifier for improving the hardness of PC resin includes the following steps: S1, under nitrogen protection, terephthalic acid, pentaerythritol triacrylate, a catalyst, and a polymerization inhibitor are added to toluene to react and obtain a compound; S2, the compound obtained in step S1 and the polymerization inhibitor are added to acetone and stirred, then nitrogen is introduced, and glycidyl methacrylate and N,N-dimethylbenzylamine are added to react and obtain a product; S3, under nitrogen protection, the product obtained in step S2 is copolymerized with acrylate monomers to obtain the modifier. The modifier prepared by this invention modifies PC resin, resulting in modified PC resin with high hardness and transparency.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a modifier for improving the hardness of PC resin and a method for preparing modified PC resin. Background Technology

[0002] Polycarbonate (PC), as a high-performance thermoplastic engineering plastic, has been widely used in many core fields such as electronics, automotive manufacturing, optical devices, and architectural lighting due to its excellent impact resistance, high transparency, wide temperature range, and good processability. With the upgrading of global manufacturing, the advancement of lightweighting trends in new energy vehicles, and the accelerated iteration of consumer electronics, the market is placing higher demands on the performance of polycarbonate materials, especially on improving hardness and rigidity. While traditional polycarbonate possesses excellent toughness, its low surface hardness and insufficient flexural modulus make it prone to scratches and deformation, failing to meet the application requirements of high-end structural components, optical components, and automotive exteriors. Therefore, the research and industrialization of high-hardness polycarbonate has become a core direction for industry development.

[0003] Patent CN117327321A discloses a transparent, high-hardness polycarbonate material, its preparation method, and its applications, comprising a polycarbonate structural layer and a functional coating. The functional coating, by weight, consists of: 20-50 parts of an organosilicon compound; 0-10 parts of nano-silica; 5-30 parts of macromolecular-weight acrylate; 30-60 parts of a diluent; and 0.1-10 parts of a photoinitiator. The polycarbonate structural layer, by weight, consists of: 80-100 parts of polycarbonate; 0-20 parts of a styrene-based polymer; 0-10 parts of a flame retardant; and 0.001-2 parts of an antioxidant. This invention also provides a method for preparing the aforementioned transparent, high-hardness polycarbonate material. The prepared transparent, high-hardness polycarbonate material has been applied in fields such as communication electronics, home appliances, automobiles, and industry, achieving good technical results. The patented solution involves a two-step process (first forming a PC structural layer, then coating and curing a functional coating). Compared to materials that are injection molded in one step, the production process is longer, there are more quality control points, and there is a risk of peeling during long-term use.

[0004] Patent CN115707735B discloses a high-hardness transparent polycarbonate material, its preparation method, and its applications. By weight, it comprises the following components: 50-85 parts polycarbonate, 15-50 parts bisphenol A polyester, and 1-10 parts hardener. This invention introduces bisphenol A polyester and hardener to form a co-compatible system between polycarbonate and hardener, solving the problems of poor surface hardness, poor flowability, and low transparency of polycarbonate materials in the prior art. The prepared polycarbonate material can be used in electronic material components such as high-frequency communication mobile phones, automotive dashboards, and LED displays.

[0005] Although existing modifiers have improved the transparency and hardness of polycarbonate materials, they still cannot meet the application requirements in some special fields. Therefore, there is an urgent need to develop a modifier that can improve the hardness of PC materials without reducing their transparency. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to obtain a PC resin modifier that can improve the hardness of PC resin without reducing its transparency.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing a modifier to improve the hardness of PC resin, comprising the following steps: S1. Under nitrogen protection, terephthalic acid, pentaerythritol triacrylate, catalyst, and polymerization inhibitor are added to toluene, stirred and heated to 100-110℃, nitrogen is introduced, and the reaction is carried out for 3-5 hours. After post-treatment, the compound is obtained. S2. Add the compound and polymerization inhibitor obtained in step S1 to acetone, stir for 20-30 min, then introduce nitrogen gas, add glycidyl methacrylate and N,N-dimethylbenzylamine, react at 100-110℃ for 4-5 h, filter, distill and wash, and dry to obtain the product. S3. Under nitrogen protection, the product obtained in step S2 is added to a solvent along with acrylate monomers and an initiator and reacted at 65-75°C to obtain a modifier.

[0008] To increase the hardness of PC materials, the commonly used methods are blending modification, which involves directly adding rigid inorganic fillers or blending with other high-hardness polymers. While this method can improve hardness, it often comes at the cost of severely sacrificing transparency, impact toughness, and processing fluidity. Secondly, surface coating can be used, applying a UV-cured or thermosetting high-hardness coating to the surface of the PC product. This method suffers from insufficient adhesion between the coating and the PC substrate, potential peeling over long-term use, complex processing, and strict requirements on the thickness and shape of the substrate. Additionally, chemical grafting modification can be used, introducing rigid groups into the PC molecular chain through a chemical reaction. This method may disrupt the PC main chain structure, leading to a significant decrease in its core mechanical properties, such as impact strength.

[0009] This invention utilizes terephthalic acid and pentaerythritol triacrylate as raw materials to generate an acrylate compound with terephthalic acid ester as a rigid center through esterification. The product of step S1 is reacted with glycidyl methacrylate and further polymerized with acrylate monomers to obtain a multifunctional modifier. PC materials prepared using this modifier exhibit improved hardness, as well as good transparency and impact resistance. This may be due to the extremely high rigidity and strength of the aromatic ring structure, which allows for uniform dispersion in the PC matrix. During the high-temperature processing of PC, the acrylate double bonds and hydroxyl groups carried on the modifier molecules can undergo local cross-linking under the influence of residual initiators or heat, forming dense cross-linking points that effectively resist external scratches and indentation, thus improving the surface hardness of the PC material. Furthermore, the good compatibility avoids light scattering and stress concentration points caused by phase separation, resulting in PC materials with high transparency.

[0010] In some embodiments, the molar ratio of terephthalic acid to pentaerythritol triacrylate is 1:(1-1.2).

[0011] In some embodiments, the mass ratio of the compound in step S2 to glycidyl methacrylate is (0.3-0.4):1.

[0012] In some embodiments, the mass ratio of the product to the acrylate monomer in step S3 is (0.04-0.1):1.

[0013] In some embodiments, the molecular weight of the modifier Mn is 40,000-50,000.

[0014] In some embodiments, the polymerization inhibitor is any one or more of p-methoxyphenol, hydroquinone, or p-benzoquinone.

[0015] In some embodiments, the acrylate monomer is a mixture of methyl methacrylate, methacrylic acid and ethyl methacrylate, wherein the mass ratio of the three is (1.8-2.2):(0.05-0.2):1.

[0016] This invention limits the ratio of terephthalic acid to pentaerythritol triacrylate, ensuring that after one carboxyl group of terephthalic acid reacts with pentaerythritol triacrylate, one carboxyl group remains capable of reacting with the epoxy group of glycidyl methacrylate. Following this, a polymerization reaction occurs. The molecular weight of the modifier is controlled to ensure good dispersibility and compatibility in the PC melt, preventing small molecule migration. Furthermore, the acrylate chain acts as a compatibilizer, buffering the interfacial stress between the rigid aromatic ring and the PC matrix, resulting in a PC material with excellent impact resistance.

[0017] A second aspect of the present invention provides a method for preparing modified PC resin, comprising the following steps: adding a modifier and PC resin to a twin-screw extruder for co-extrusion.

[0018] In some embodiments, the extrusion temperature of the twin-screw extruder is 260-300°C.

[0019] In some embodiments, the mass ratio of the modifier to the PC resin is (0.1-0.4):1.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention provides a modifier that can improve the hardness of PC and a method for preparing modified PC resin. The modified PC resin prepared has high transparency and hardness.

[0021] (2) The present invention prepares a multifunctional organic modifier, and finally combines the modifier with PC resin by melt blending. This method solves the problems of traditional blending modification that easily sacrifices transparency and toughness, poor surface coating adhesion and complex process, and chemical grafting that may destroy the PC main chain structure and lead to a decrease in mechanical properties. It significantly improves the surface hardness of PC material while maintaining its excellent transparency. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of the invention. Various modifications and variations to the specific embodiments described in this specification are apparent to those skilled in the art without departing from the scope or spirit of the invention. Other embodiments derived from this specification will be apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0025] In the following examples and comparative examples, the compounds and related reagents used were all commercially available. The polycarbonate used was bisphenol A type polycarbonate, grade 1320C-07, and branded by LG Korea.

[0026] Unless otherwise specified, the post-processing steps such as "washing", "drying", "filtration", "rotary evaporation", and "distillation" used below are routine operations for those skilled in the art, and can be selected according to actual operations.

[0027] Example 1 A method for preparing a modifier to improve the hardness of PC resin includes the following steps: S1. Under nitrogen protection, 1 mol of terephthalic acid, 1.1 mol of pentaerythritol triacrylate, 9 g of p-toluenesulfonic acid, and 0.9 g of p-methoxyphenol were added to 1000 g of toluene. The mixture was stirred and heated to 105 °C, nitrogen was introduced, and the reaction was carried out for 4 h. The mixture was washed successively with saturated sodium carbonate solution and saturated brine, dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the compound. S2. Add 3.7g of the compound obtained in step S1 and 0.02g of p-methoxyphenol to 50g of acetone, stir for 25min, then purge with nitrogen, add 10g of glycidyl methacrylate and 0.15g of N,N-dimethylbenzylamine, react at 105℃ for 4.5h, filter, distill and wash, and dry to obtain the product. S3. Under nitrogen protection, 6g of the product obtained in step S2, 100g of acrylate monomers, and 0.5g of benzoyl peroxide were added to 100ml of toluene and reacted at 70℃. During the reaction, Mn was detected by gel permeation chromatography, and a modifier with Mn=48243 was obtained. A mixture of methyl methacrylate, methacrylic acid, and ethyl methacrylate was prepared with a mass ratio of 2:0.1:1.

[0028] The method for preparing modified PC resin in this embodiment includes the following steps: adding modifier and PC resin to a twin-screw extruder at a mass ratio of 0.3:1 and mixing them together, then extruding at 280°C to obtain modified PC resin.

[0029] Example 2 A method for preparing a modifier to improve the hardness of PC resin includes the following steps: S1. Under nitrogen protection, 1 mol of terephthalic acid, 1 mol of pentaerythritol triacrylate, 9 g of p-toluenesulfonic acid, and 0.9 g of p-methoxyphenol were added to 1000 g of toluene. The mixture was stirred and heated to 100 °C, nitrogen was introduced, and the reaction was carried out for 5 h. The mixture was washed successively with saturated sodium carbonate solution and saturated brine, dried over anhydrous sulfuric acid, filtered, and rotary evaporated to obtain the compound. S2. Add 3g of the compound obtained in step S1 and 0.02g of p-methoxyphenol to 50g of acetone, stir for 20min, then introduce nitrogen gas, add 10g of glycidyl methacrylate and 0.15g of N,N-dimethylbenzylamine, react at 100℃ for 5h, filter, distill and wash, and dry to obtain the product. S3. Under nitrogen protection, 4g of the product obtained in step S2, 100g of acrylate monomers, and 0.5g of benzoyl peroxide were added to 100ml of toluene and reacted at 65℃. During the reaction, Mn was detected by gel permeation chromatography, and a modifier with Mn=47236 was obtained. The mixture of methyl methacrylate, methacrylic acid, and ethyl methacrylate had a mass ratio of 1.8:0.12:1.

[0030] The method for preparing modified PC resin in this embodiment includes the following steps: adding modifier and PC resin to a twin-screw extruder at a mass ratio of 0.1:1 and mixing them together, then extruding at 260°C to obtain modified PC resin.

[0031] Example 3 A method for preparing a modifier to improve the hardness of PC resin includes the following steps: S1. Under nitrogen protection, 1 mol of terephthalic acid, 1.2 mol of pentaerythritol triacrylate, 9 g of p-toluenesulfonate, and 0.9 g of p-methoxyphenol were added to 1000 g of toluene. The mixture was stirred and heated to 110 °C, and nitrogen was introduced. The reaction was carried out for 3 h. The mixture was washed successively with saturated sodium carbonate solution and saturated brine, dried over anhydrous magnesium sulfate, filtered, and rotary evaporated to obtain the compound. S2. Add 4g of the compound obtained in step S1 and 0.02g of p-methoxyphenol to 50g of acetone, stir for 20min, then introduce nitrogen gas, add 10g of glycidyl methacrylate and 0.15g of N,N-dimethylbenzylamine, react at 110℃ for 4h, filter, distill and wash, and dry to obtain the product. S3. Under nitrogen protection, 10g of the product obtained in step S2, 100g of acrylate monomers, and 0.5g of benzoyl peroxide were added to 100ml of toluene and reacted at 75℃. During the reaction, Mn was detected by gel permeation chromatography, and a modifier with Mn=49583 was obtained. The mixture of methyl methacrylate, methacrylic acid, and ethyl methacrylate had a mass ratio of 2.2:0.2:1.

[0032] The method for preparing modified PC resin in this embodiment includes the following steps: adding modifier and PC resin to a twin-screw extruder at a mass ratio of 0.4:1 and mixing them together, then extruding at 300°C to obtain modified PC resin.

[0033] Example 4 A modifier for improving the hardness of PC resin and a method for preparing modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that terephthalic acid is replaced with succinic acid in an equal amount.

[0034] Example 5 A modifier for improving the hardness of PC resin and a method for preparing modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that the amount of pentaerythritol triacrylate added is 1.6 mol.

[0035] Example 6 A modifier for improving the hardness of PC resin and a method for preparing modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that the amount of compound added in step S2 is 5g.

[0036] Example 7 A modifier for improving the hardness of PC resin and a method for preparing modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that the amount of product added in step S3 is 12g.

[0037] Example 8 A modifier for improving the hardness of PC resin and a method for preparing modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that the mixture of methyl methacrylate, methacrylic acid and ethyl methacrylate has a mass ratio of 2.5:0.1:1.

[0038] Example 9 A modifier for improving the hardness of PC resin and a method for preparing the modified PC resin are disclosed. The specific implementation method is the same as in Example 1, except that the acrylate monomer is methacrylate.

[0039] Performance testing The modified PC resins obtained in each embodiment were used to make injection molded samples with a thickness of 2 mm, and the following tests were performed: 1. Light transmittance: The light transmittance of the injection molded sample was measured according to ASTM D1003; 2. Surface hardness: The surface hardness was tested using a pencil hardness tester according to ASTM D3363.

[0040] The test results are shown in Table 1: Table 1 As shown in Table 1, the modified PC resins prepared in Examples 1-3 exhibit good transparency and hardness. A comparison of the data from Example 4 and Example 1 shows that replacing terephthalic acid with succinic acid in equal amounts may decrease the rigidity of the modifier's molecular chain and weaken its compatibility with PC resin, resulting in a decrease in both transparency and hardness of the modified PC resin. A comparison of the data from Example 5 and Example 1 shows that changing the ratio of terephthalic acid to pentaerythritol triacrylate increases the branching degree and crosslinking points of the synthesized modifier, making it prone to gelation and leading to a decrease in the transparency of the modified PC resin. A comparison of the data from Example 6 and Example 1 shows that the compound and glycidyl methacrylate... Changes in the formulation ratio may lead to increased side reactions and a wider molecular weight distribution, resulting in a decrease in the hardness of the modified PC resin. A comparison of Example 7 and Example 1 shows that changes in the ratio of the product to the acrylate monomers may cause a small amount of modifier to precipitate or form micro-aggregates, reducing the transparency of the modified PC resin. A comparison of Example 8 and Example 1 shows that changes in the ratio of the various substances in the acrylate monomers result in an excessive amount of PMMA segments in the modifier, leading to a larger difference between the overall refractive index of the modifier and the refractive index of the PC matrix, thus reducing the transparency of the modified PC resin. A comparison of Example 9 and Example 1 shows that using only a single acrylate monomer reduces the number of crosslinking sites, resulting in a decrease in the hardness of the modified PC resin.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present application in any way. Although the present application discloses the preferred embodiment as described above, it is not intended to limit the present application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of the present application using the disclosed technical content are equivalent to equivalent implementation cases. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A method for preparing a modifier to improve the hardness of PC resin, characterized in that, Includes the following steps: S1. Under nitrogen protection, terephthalic acid, pentaerythritol triacrylate, catalyst, and polymerization inhibitor are added to toluene, stirred and heated to 100-110℃, nitrogen is introduced, and the reaction is carried out for 3-5 hours. After post-treatment, the compound is obtained. S2. Add the compound and polymerization inhibitor obtained in step S1 to acetone, stir for 20-30 min, then introduce nitrogen gas, add glycidyl methacrylate and N,N-dimethylbenzylamine, react at 100-110℃ for 4-5 h, filter, distill and wash, and dry to obtain the product. S3. Under nitrogen protection, the product obtained in step S2 is added to a solvent along with acrylate monomers and an initiator and reacted at 65-75°C to obtain a modifier.

2. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The molar ratio of terephthalic acid to pentaerythritol triacrylate is 1:(1-1.2).

3. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The mass ratio of the compound in step S2 to glycidyl methacrylate is (0.3-0.4):

1.

4. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The mass ratio of the product to the acrylate monomer in step S3 is (0.04-0.1):

1.

5. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The molecular weight of the modifier is Mn = 40,000-50,000.

6. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The polymerization inhibitor is any one or more of p-methoxyphenol, hydroquinone, or p-benzoquinone.

7. The method for preparing the modifier for improving the hardness of PC resin according to claim 1, characterized in that, The acrylate monomers are a mixture of methyl methacrylate, methacrylic acid and ethyl methacrylate, in a mass ratio of (1.8-2.2):(0.05-0.2):

1.

8. A method for preparing a modified PC resin, characterized in that, The method includes the following steps: adding a modifier and PC resin to a twin-screw extruder for co-extrusion; wherein the modifier is obtained by the preparation method according to any one of claims 1-7.

9. The method for preparing the modified PC resin according to claim 8, characterized in that, The extrusion temperature of the twin-screw extruder is 260-300℃.

10. The method for preparing the modified PC resin according to claim 8, characterized in that, The mass ratio of the modifier to the PC resin is (0.1-0.4):1.

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