A PC / polyester alloy material special for automobile grilles and a preparation method thereof

Abstract

The application relates to the field of high polymer materials, in particular to a PC / polyester alloy material special for automobile grilles, which is composed of the following components and the following weight parts: PC resin 30-70 parts, polyester a 10-40 parts, polyester b 1-20 parts, toughening agent 1-10 parts, antioxidant 0.1-1 part, lubricant 0.1-1 part, ester exchange inhibitor 0.1-3 parts and nucleating agent 0.1-3 parts. The application further provides a preparation method of the PC / polyester alloy. The alloy material has good thermal stability in a forming process; after paint spraying, the alloy material still has good impact toughness and size stability after long-term placement, and is particularly suitable for automobile grille products.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a PC / polyester alloy material for automotive grilles and its preparation method. Background Technology

[0002] The front grille is a key component of a car's exterior, serving not only functions such as heat dissipation, air intake, and impact protection, but also playing a crucial role in showcasing the brand's design language and the vehicle's visual impact. As automotive design increasingly leans towards personalization, luxury, and low-tolerance assembly, the performance requirements for grille materials are also rising: they need to possess excellent aesthetic appeal (high gloss, easy painting, scratch resistance), superior mechanical properties (high rigidity, high impact toughness), outstanding weather resistance, and good processability.

[0003] Currently, the main materials used to manufacture high-end automotive grilles are electroplating-grade ABS, ASA, and polycarbonate (PC) and its alloys. Polycarbonate (PC) is a linear polycarbonate, an amorphous engineering plastic with good toughness, transparency, and heat resistance. Crystalline PET has high rigidity, strength, and chemical resistance, allowing products to maintain dimensional stability over a wider temperature range and meet the environmental requirements of the automotive engine compartment. Therefore, PC / PET polyester materials are often used as dedicated materials for automotive grille products. However, PC and PET are thermodynamically incompatible systems. Simple blending leads to weak interfacial bonding, becoming a weak point in the material's mechanical properties. Furthermore, both PC and PET are polyester structures, prone to transesterification reactions during melt blending. If the degree of transesterification is low, the two materials have poor compatibility and cannot exhibit good mechanical properties. Excessive transesterification can severely damage the structure of both PC and PET, producing too many small molecules, leading to serious performance degradation. Especially after painting, the slow corrosion from the paint significantly impacts impact resistance. The crystallization rate and crystallinity of PET are sensitive to the processing temperature. Uneven crystallization may cause warping and deformation of the product, affecting the high-precision assembly of the grille and the car body.

[0004] Therefore, the development of a PC / polyester alloy with stable long-term performance and dimensions after painting is of great significance for the application of automotive grilles.

[0005] Chinese patent document CN107556724A discloses a high-flowability, high-toughness PC / PET composite material. This composite material, without the use of compatibilizers or chain extenders, utilizes a toughening agent with a special structure, exhibiting extremely high toughening efficiency with minimal impact on the composite's flowability. This improves the composite's thermal stability and ensures its mechanical properties. The flowability, toughness, and thermal stability of this composite material are significantly optimized, making it particularly suitable for applications with high flowability requirements and demanding environmental conditions. This patent achieves toughening and reduces the impact of the toughening agent on flowability by using a styrene-butadiene-glycidyl methacrylate terpolymer (SBG) instead of glycidyl methacrylate as the toughening agent. The patent does not address the long-term performance stability after painting.

[0006] Chinese patent document CN101712794B discloses a low-temperature resistant PC / PET composite material and its preparation method. This composite material is prepared by drying and stirring PC, PET, compatibilizer, toughening agent, low-temperature modifier, and antioxidant, followed by melt extrusion granulation in a twin-screw extruder. The material retains over 90% of its notched cantilever beam strength at -30°C relative to room temperature, reaching nearly 700 J / m. However, this patent does not address the long-term performance stability after painting.

[0007] However, there are currently no reports on a PC / polyester alloy material with long-term performance and dimensional stability after painting suitable for automotive grilles, nor on its preparation method. Summary of the Invention

[0008] The purpose of this invention is to provide a PC / polyester alloy material for automotive grilles and its preparation method.

[0009] In a first aspect, the present invention provides a PC / polyester alloy material for automotive grilles, comprising the following components in the following weight proportions:

[0010] 30-70 parts of PC resin

[0011] Polyester a 10-40 parts,

[0012] Polyester b 1-20 parts,

[0013] 1-10 parts toughening agent

[0014] Antioxidant 0.1-1 part,

[0015] Lubricant 0.1-1 part,

[0016] Transesterification inhibitor 0.1-3 parts,

[0017] Nucleating agent 0.1-3 parts;

[0018] Further, the PC resin is a bisphenol A type polycarbonate with a weight-average molecular weight of 17,000–30,000 g / mol and a glass transition temperature of 145–150 °C. Specifically, it can be Teijin Chemical L-1225Y, Shengxi'ao PC 1201-10 or PC1201-22, Hunan Petrochemical PC1100 or PC1220, or Covestro PC 2800 or PC 2400. Shengxi'ao PC 1201-10 or PC 1201-22 is preferred.

[0019] Furthermore, the polyester a is polyethylene terephthalate (PET) with an intrinsic viscosity of 0.75–1.0 dl / g. Specifically, CB608S from Taiwan Far Eastern Textile Co., Ltd. can be used, with an intrinsic viscosity of 0.8 dl / g.

[0020] Further, the polyester b is polyethylene terephthalate-1,4-cyclohexanediethanol (PCTG) or polyethylene terephthalate-1,4-cyclohexanediethanol (PETG), with an intrinsic viscosity of 0.70–1.0 dl / g. Specifically, SK's JN200 resin can be used for PCTG, with an intrinsic viscosity of 0.75 dl / g; SK's IT-806 resin can be used for PETG, with an intrinsic viscosity of 0.75 dl / g.

[0021] Further, the toughening agent is a methyl methacrylate-butadiene-styrene copolymer (MBS) or a methyl methacrylate / acrylic acid polymer (ACR) with a particle size of 50-700 nm and a glue content of 40 wt%-90 wt%. Specifically, LG's EM500, Kaneka's M521, Dow's EXL-2620, and EXL-2330 can be selected; wherein EM500, M521, and EXL-2620 are all methyl methacrylate-butadiene-styrene copolymers (MBS), and EXL-2330 belongs to methyl methacrylate / acrylic acid polymers (ACR); Dow's EXL-2620 is preferred.

[0022] Furthermore, the antioxidant is selected from one or more of phosphite antioxidant 168, phosphite antioxidant S-9228, hindered phenolic antioxidant 1010, hindered phenolic antioxidant 1098, and hindered phenolic antioxidant 1076. Preferably, phosphite antioxidant S-9228 and hindered phenolic antioxidant 1010 are used in combination at a weight ratio of 1:1.

[0023] Furthermore, the lubricant is selected from one or more of silicone powder, pentaerythritol ester (PETS), and ethylene bis-stearamide. Pentaerythritol ester (PETS) is preferred.

[0024] Furthermore, the transesterification inhibitor is selected from one or more of phosphites, epoxy compounds, and carbodiimides. Preferably, Basf's ADR-4368 epoxy resin and Changhe Chemical's triphenyl phosphite are used in a compound ratio of 1:1 by weight.

[0025] Furthermore, the nucleating agent is one or more of ultrafine talc powder and ionic polymers. The ultrafine talc powder has a D50 of 0.65 μm. Preferably, it is HTPULTRA 5 from Immelfab, with a D50 of 0.65 μm.

[0026] In a preferred embodiment of the present invention, the automotive grille-specific PC polyester alloy material is composed of the following components in the following weight parts:

[0027] PC resin 62.6-63.1 parts,

[0028] Polyester a 20 parts,

[0029] Polyester b 10 parts,

[0030] 5 parts toughening agent

[0031] 0.4 parts antioxidant,

[0032] 0.6 parts lubricant,

[0033] Transesterification inhibitor 0.4 parts,

[0034] Nucleating agent 0.5-1 part;

[0035] In the preferred embodiment described above,

[0036] The selected PC resin is Shengxi's PC 1201-22;

[0037] The selected polyester resin was CB608S from Taiwan Far Eastern Textile Co., Ltd., with an intrinsic viscosity of 0.8 dl / g.

[0038] The selected polyester resin was SK's JN200, with an intrinsic viscosity of 0.75 dl / g;

[0039] The toughening agent selected was Dow's EXL-2620;

[0040] The selected antioxidants are Basf antioxidants S-9228 and 1010, with a weight ratio of 1:1.

[0041] The lubricant selected is pentaerythritol ester (PETS).

[0042] The selected transesterification inhibitors were Basf's ADR-4368 epoxy resin and Changhe Chemical's triphenyl phosphite, with a weight ratio of 1:1.

[0043] The nucleating agent selected was Im-Mefavi HTPULTRA 5, with a D50 of 0.65 μm.

[0044] A second aspect of the present invention provides a method for preparing the PC polyester alloy material for automotive grilles as described above, comprising the following steps:

[0045] S1. Prepare the raw materials according to the weight ratio, put them into the premixer to mix the raw materials evenly, heat to 60°C and keep warm for 15 minutes to obtain the premix.

[0046] S2. Add the premix obtained in step S1 into a twin-screw extruder, extrude and pelletize to obtain PC / polyester alloy material, wherein the barrel speed of the twin-screw extruder is 15-35 rpm and the barrel temperature is 220-270℃.

[0047] S3. The PC / polyester material obtained in step S2 is injection molded to obtain the finished product.

[0048] Furthermore, in step S2, six sets of shear blocks are used in the screw assembly.

[0049] Compared with the prior art, the advantages of the PC / polyester alloy material for automotive grilles and its preparation method of the present invention are as follows:

[0050] 1. Regarding the chemical resistance and stability of the material after painting: 1) The impact performance was improved by adding amorphous PCTG; 2) The risk of excessive transesterification degradation of PC and polyester was further reduced by the combined use of transesterification inhibitor ADR-4368 epoxy resin and triphenyl phosphite; 3) The risk of transesterification degradation was also significantly reduced by reducing the number of shear blocks in the screw assembly from 9 to 6, which significantly improved the impact performance and thermal stability.

[0051] 2. Regarding dimensional stability: 1) Because PET is a semi-crystalline material, post-crystallization may occur during subsequent storage, leading to dimensional changes. This invention improves the dimensional stability of the material by adding amorphous PCTG, thereby reducing the amount of PET added. 2) The addition of ultrafine talc powder (D50 of 0.65um) promotes uniform nucleation and reduces post-crystallization; it also increases rigidity and inhibits shrinkage deformation.

[0052] 3. The alloy material of the present invention has excellent thermal stability during the molding process; after being painted and left for a long time, it still has excellent impact toughness and dimensional stability, making it particularly suitable for automotive grille products. Detailed Implementation

[0053] The specific implementation methods provided by the present invention will be described in detail below with reference to the embodiments.

[0054] In the following embodiments and comparative examples, the raw materials use the following components:

[0055] The selected PC resin is Shengxi's PC 1201-22;

[0056] The selected polyester resin is CB608S from Taiwan Far Eastern Textile Co., Ltd.

[0057] The selected polyester resin is SK's JN200 or IT-806;

[0058] The toughening agent selected was Dow's EXL-2620;

[0059] The selected antioxidants are a combination of antioxidants 1010 and S-9228 produced by Basf, in a weight ratio of 1:1.

[0060] The lubricant selected is pentaerythritol ester (PETS).

[0061] The selected transesterification inhibitors were Basf's ADR-4368 epoxy resin and Changhe Chemical's phosphite, with a weight ratio of 1:1.

[0062] The nucleating agent selected was Im-Mefavi HTPULTRA 5, with a D50 of 0.65 μm.

[0063] Table 1. Components and proportions of Comparative Examples 1–6

[0064]

[0065] Table 2 Components and proportions of Examples 1-3

[0066]

[0067] Comparative Examples 1-6:

[0068] S1. Prepare the raw materials according to the weight ratio, put them into the premixer to mix the raw materials evenly, heat to 60°C and keep warm for 15 minutes to obtain the premix.

[0069] S2. Add the premix obtained in step S1 into a twin-screw extruder, extrude and pelletize to obtain PC / polyester alloy material, wherein the barrel speed of the twin-screw extruder is 15-35 rpm, the barrel temperature is 220-270℃, and 9 sets of shear blocks are used.

[0070] S3. The PC / polyester alloy material obtained in step S2 is injection molded to obtain the finished product.

[0071] Examples 1-2:

[0072] S1. Prepare the raw materials according to the weight ratio, put them into the premixer to mix the raw materials evenly, heat to 60°C and keep warm for 15 minutes to obtain the premix.

[0073] S2. Add the premix obtained in step S1 into a twin-screw extruder, extrude and pelletize to obtain PC / polyester alloy material, wherein the barrel speed of the twin-screw extruder is 15-35 rpm, the barrel temperature is 220-270℃, and 9 sets of shear blocks are used in the screw assembly.

[0074] S3. The PC / polyester alloy material obtained in step S2 is injection molded to obtain the finished product.

[0075] Example 3:

[0076] S1. Prepare the raw materials according to the weight ratio, put them into the premixer to mix the raw materials evenly, heat to 60°C and keep warm for 15 minutes to obtain the premix.

[0077] S2. Add the premix obtained in step S1 into a twin-screw extruder, extrude and pelletize to obtain PC / polyester alloy material, wherein the barrel speed of the twin-screw extruder is 15-35 rpm, the barrel temperature is 220-270℃, and 6 sets of shear blocks are used in the screw assembly.

[0078] S3. The PC / polyester alloy material obtained in step S2 is injection molded to obtain the finished product.

[0079] Example 4: Evaluation of Implementation Results

[0080] The PC / polyester prepared in Comparative Examples 1-6 and Examples 1-3 were subjected to relevant tests:

[0081] Melt flow index was determined according to ISO 1133-1, at a test temperature of 260℃. 5kg;

[0082] Notched impact strength was tested according to ISO 179-1 at 23°C.

[0083] Chemical resistance assessment involves taking samples from injection-molded parts that have been coated with exterior paint and then placing them for different periods of time as required, and then performing notched impact tests on the parts.

[0084] Thermal stability was assessed on an injection molding machine. The machine was set to a heating temperature of 270℃. PC / polyester materials were left in the injection molding machine for 7 minutes and 10 minutes respectively, and then injection molded samples were made. The presence of silver streaks on the sample surface was observed. Generally, the more severe the silver streaks, the worse the thermal stability of the material.

[0085] Dimensional stability was achieved during injection molding at 270℃ and a mold temperature of 80℃ for 100 seconds. 150 A 3mm sample is then treated in an 80℃ oven for 24 hours, and the dimensional changes before and after the experiment are measured. This dimensional change is the material's post-shrinkage.

[0086] Table 3 Test results of Comparative Examples 1–6

[0087]

[0088] Table 4 Test results of Examples 1-3

[0089]

[0090] As can be seen from Comparative Examples 1, 2, and 4, since both PCTG JN200 and PETG IT-806 are amorphous polyester materials, they have better toughness than PET materials, resulting in better impact performance after painting. Compared with PETG, PCTG has a better Vicat softening temperature, making it a better choice.

[0091] As can be seen from Comparative Examples 1 and 2-3, the impact performance is significantly improved with the increase of PCTG addition. This is because amorphous PCTG has better impact performance than semi-crystalline PET. However, the Vicat softening temperature is lower. In terms of dimensional stability, since amorphous PCTG does not have the problem of shrinkage after crystallization, the addition of PCTG helps with dimensional stability.

[0092] As can be seen from Comparative Examples 2, 5, and 6, the addition of epoxy resin ADR-4368 and phosphite greatly improves impact performance because these two additives can reduce the transesterification degradation of PC and polyester. The reduction of small molecules generated by transesterification degradation also ensures long-term impact stability after painting. Because there are fewer thermally degradable small molecules, it maintains excellent thermal stability in the 270°C heat dwell test.

[0093] As can be seen from Comparative Examples 2 and 5, and Examples 1 and 2, the addition of ultrafine talc HTPULTRA 5 can accelerate the crystallization rate of PET materials, thus significantly improving the post-crystallization of the materials and resulting in a noticeable improvement in post-shrinkage. A significant effect is achieved at an addition level of 0.5%, but further increasing the proportion to 1% has some negative impact on impact performance because it is an inorganic substance.

[0094] As seen in Examples 1 and 3, while nine shear blocks are conventionally used in the extrusion granulation process of PC / polyester materials, Example 3 reduces the number of shear blocks to six. This significantly reduces the degree of transesterification reaction between PC and polyester, resulting in a marked improvement in impact performance and thermal stability. Example 3 ultimately achieves excellent retention of impact performance, good thermal stability, and dimensional stability after painting, making it ideal for automotive grille products and representing the optimal solution.

[0095] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A PC / polyester alloy material specifically for automotive grilles, characterized in that, It is composed of the following ingredients in the following parts by weight: 30-70 parts of PC resin Polyester a 10-40 parts, Polyester b 1-20 parts, Toughening agent 1-10 parts, Antioxidant 0.1-1 part, Lubricant 0.1-1 part, Transesterification inhibitor 0.1-3 parts, Nucleating agent 0.1-3 parts; The polyester a is polyethylene terephthalate (PET) with an intrinsic viscosity of 0.75–1.0 dl / g; The polyester b is poly(1,4-cyclohexanediethanol terephthalate) PCTG or polyethylene terephthalate (PETG), with an intrinsic viscosity of 0.70–1.0 dl / g.

2. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The PC resin is a bisphenol A type polycarbonate with a weight-average molecular weight of 17,000 to 30,000 g / mol and a glass transition temperature of 145 to 150 °C.

3. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The toughening agent is a methyl methacrylate-butadiene-styrene copolymer (MBS) or a methyl methacrylate / acrylic polymer (ACR) with a particle size of 50-700 nm and a glue content of 40 wt%-90 wt%.

4. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The antioxidant is selected from one or more of the following: phosphite antioxidant 168, phosphite antioxidant S-9228, hindered phenolic antioxidant 1010, hindered phenolic antioxidant 1098, and hindered phenolic antioxidant 1076.

5. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The lubricant is selected from one or more of silicone powder, pentaerythritol ester, and ethylene bis-stearamide.

6. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The transesterification inhibitor is selected from one or more of phosphites, epoxides, and carbodiimides.

7. The PC / polyester alloy material for automotive grilles according to claim 6, characterized in that, The transesterification inhibitor is ADR-4368 epoxy resin and triphenyl phosphite in a weight ratio of 1:

1.

8. The PC / polyester alloy material for automotive grilles according to claim 1, characterized in that, The nucleating agent is one or more of ultrafine talc powder and ionic polymer; the ultrafine talc powder has a D50 of 0.65 μm.

9. A method for preparing a PC / polyester alloy material for automotive grilles as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Prepare the raw materials according to the weight ratio, put them into the premixer to mix the raw materials evenly, and heat to... After holding at 60℃ for 15 minutes, a premix is ​​obtained. S2. Add the premix obtained in step S1 into a twin-screw extruder, extrude and pelletize to obtain PC / Polyester alloy material, wherein the barrel speed of the twin-screw extruder is 15-35 rpm and the barrel temperature is 220-270℃; S3. The PC / polyester material obtained in step S2 is injection molded to obtain the finished product.

10. The method for preparing the PC / polyester alloy material for automotive grilles according to claim 8, characterized in that, In step S2, six sets of shear blocks are used in the screw assembly.

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