Glass fiber reinforced PC / ABS (Polycarbonate / Acrylonitrile Butadiene Styrene) composite material with high weld mark strength and preparation method thereof

Abstract

The invention discloses a glass fiber reinforced PC / ABS (Polycarbonate / Acrylonitrile Butadiene Styrene) composite material with high weld mark strength and a preparation method of the glass fiber reinforced PC / ABS composite material, and belongs to the technical field of polymer modified materials for automobiles. The modified material is composed of the following components in percentage by weight: 40-60 wt% of PC resin; 25 to 45 wt% of ABS resin; 3-8 wt% of a composite compatilizer; 5 to 15 wt% of surface modified flat glass fiber; 2 to 6 wt% of a flexibilizer; 0.2 to 0.5 wt% of a lubricant; 0.5 wt% of carbon black; and 0.1-3 wt% of other auxiliary agents. According to the invention, the interfacial compatibility of PC and ABS is improved through the composite compatilizer, and the weld mark strength of the PC / ABS material is remarkably improved on the basis of combination of dispersion strengthening and high interface action of the surface-modified flat glass fiber, cooperation with the synergistic toughening effect of the core-shell structure toughening agent and combination of preparation process parameters; meanwhile, excellent impact strength, tensile strength and processing fluidity of the material are kept.

Description

Technical Field

[0001] This invention relates to the field of polymer material modification technology, specifically to a glass fiber reinforced PC / ABS composite material with high weld line strength and its preparation method, which is particularly suitable for injection molding of complex structural parts in the automotive industry. Background Technology

[0002] PC / ABS alloy materials combine the excellent heat resistance, impact resistance and dimensional stability of polycarbonate (PC) with the good processing fluidity and cost advantages of acrylonitrile-butadiene-styrene copolymer (ABS), and are widely used in the manufacture of automotive interior parts (such as dashboards and door panels) and exterior parts (such as grilles and bumper brackets).

[0003] During the injection molding process of automotive parts, due to the complex structure of the product (such as the presence of holes, ribs, and complex cavities), the melt will split and then rejoin within the mold, forming weld lines (also known as weld seams). Weld lines are weak points in injection molded parts, and their strength is usually much lower than that of the material itself. During the long-term use of automotive parts, weld lines are prone to cracking and breakage, seriously affecting the product's service life and safety.

[0004] Existing technologies for improving weld line strength in PC / ABS materials mainly include: adding compatibilizers to improve the interfacial compatibility between PC and ABS, introducing reinforcing fillers to improve the bonding strength at the weld, and optimizing processing parameters. However, existing technologies have the following shortcomings: a single compatibilizer is insufficient to fully improve the interfacial bonding between PC and ABS, resulting in insufficient interfacial adhesion at the weld line; conventional glass fibers are unevenly dispersed at the weld line and have poor bonding strength with the resin matrix, failing to effectively transfer stress; toughening agents have poor compatibility with the PC / ABS matrix. Improving weld line strength can easily lead to a decrease in the material's bulk mechanical properties. Therefore, developing a PC / ABS modified material that balances high weld line strength, excellent bulk mechanical properties, and good processing flowability is of great significance for meeting the stringent requirements of the automotive industry. Summary of the Invention

[0005] To address the problem of insufficient weld line strength in existing PC / ABS materials, this invention proposes a high weld line strength PC / ABS composite material and its preparation method. By optimizing the formulation and preparation process, the weld line strength is significantly improved while ensuring the material's mechanical properties and processing fluidity, thus meeting the usage requirements of complex automotive structural components.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A glass fiber reinforced PC / ABS composite material with high weld line strength, comprising the following raw materials by weight percentage:

[0008] PC resin: 40-60 wt%;

[0009] ABS resin: 25-45 wt%;

[0010] Composite compatibilizer: 3-8 wt%;

[0011] Surface-modified flat glass fiber: 5-15 wt%;

[0012] Toughening agent: 2-6 wt%;

[0013] Lubricant: 0.2–0.5 wt%;

[0014] Carbon black: 0.5 wt%;

[0015] Other additives: 0.1-3 wt%.

[0016] The PC resin has a number-average molecular weight of 2.2w to 3w and a melt flow rate (300℃ / 1.2kg) of 10 to 20g / 10min.

[0017] The ABS resin has an acrylonitrile content of 23-30 wt%, a butadiene content of 18-26 wt%, and a melt flow rate (220℃ / 10kg) of 15-25 g / 10min.

[0018] The composite compatibilizer is a compound of maleic anhydride-grafted ABS (MAH-g-ABS) and styrene / acrylonitrile copolymer-grafted glycidyl methacrylate (SAN-g-GMA), with a weight ratio of 1:0.5 to 1:2.

[0019] The surface-modified flat glass fiber is an alkali-free chopped flat glass fiber treated with a silane coupling agent, with a flatness ratio of 1.8-4.2% and a chopped glass fiber length of 1-3 mm.

[0020] The toughening agent is a core-shell structured methyl methacrylate-butadiene-styrene terpolymer (MBS).

[0021] The lubricant is one or a combination of two of vinyl bis-stearamide (EBS) and pentaerythritol stearate (PETS).

[0022] The other adjuvants are primary antioxidants and secondary antioxidants, wherein the primary and secondary antioxidants are one or more compounds such as 1010 and antioxidant 168.

[0023] A glass fiber reinforced PC / ABS composite material with high weld line strength is prepared by the following steps:

[0024] (1) Dry the PC resin at 120℃ for 4-6 hours, the ABS resin at 80℃-90℃ for 2-3 hours, and the surface-modified flat glass fiber at 100℃-110℃ for 3-4 hours to remove moisture.

[0025] (2) First, weigh PC resin, ABS resin, compatibilizer, toughening agent, lubricant, carbon black and other additives according to the weight proportions, and then homogenize them in a high-speed mixer to obtain mixed raw materials.

[0026] (3) The above mixed raw materials are placed in the main feed bin of the co-rotating twin-screw extruder, and the surface-modified flat glass fiber is placed in the side feed bin of the co-rotating twin-screw extruder. The fiber is then fed into the barrel of the extruder through the side feed screw. After melt extrusion, cooling, granulation and drying, a glass fiber reinforced PC / ABS composite material with high weld line strength is obtained.

[0027] The beneficial effects of this invention are:

[0028] 1. A composite compatibilizer consisting of MAH-g-ABS and SAN-g-GMA is used. The maleic anhydride group of MAH-g-ABS reacts with the terminal hydroxyl group of PC, and the epoxy group of SAN-g-GMA reacts with the amino group of ABS. This synergistically strengthens the interfacial bonding between PC and ABS and significantly improves the interfacial adhesion at the weld line.

[0029] 2. Flat glass fibers treated with silane coupling agent form a strong chemical bond with the matrix on the one hand, and the flat shape increases the contact and convergence between the filler and the resin on the other hand, so that they are evenly dispersed at the weld line and effectively transfer stress. At the same time, the short glass fibers are 1-3mm to avoid the adverse effects of excessive length on the processing fluidity.

[0030] 3. The shell layer of the core-shell toughening agent MBS, PMMA, has good compatibility with PC, while the core layer, PB / PS copolymer, has good compatibility with ABS and forms an elastic network at the weld line, which can absorb impact energy and improve tear resistance. Detailed Implementation

[0031] The present invention can be further described through the following preferred embodiments, but these embodiments are only illustrative and do not define the scope of the present invention.

[0032] In the composite material formulations of the examples and comparative examples, the raw materials involved are:

[0033] The PC resin has a number average molecular weight of 2.2w to 3w and a melt flow rate (300℃ / 1.2kg) of 10 to 20g / 10min. It is commercially available.

[0034] The ABS resin has an acrylonitrile content of 23-30 wt%, a butadiene content of 18-26 wt%, and a melt flow rate (220℃ / 10kg) of 15-25 g / 10min. It is commercially available.

[0035] The composite compatibilizer is a compound of maleic anhydride-grafted ABS (MAH-g-ABS) and styrene / acrylonitrile copolymer-grafted glycidyl methacrylate (SAN-g-GMA), which is commercially available.

[0036] Surface-modified flat glass fiber is alkali-free chopped flat glass fiber treated with silane coupling agent, with a flatness ratio of 1.8-4.2% and a chopped glass fiber length of 1-3 mm, commercially available;

[0037] The toughening agent is a core-shell structured methyl methacrylate-butadiene-styrene terpolymer (MBS), which is commercially available.

[0038] The lubricant is one or a combination of two of vinyl bis-stearamide (EBS) or pentaerythritol stearate (PETS), and is commercially available.

[0039] Other adjuvants are primary antioxidants and secondary antioxidants, among which the primary and secondary antioxidants are one or more compounds such as 1010 and antioxidant 168, which are commercially available.

[0040] The test methods for the examples and comparative examples are as follows: melt flow index is tested according to ISO 1133; weld line strength is tested according to ISO 527-2; weld line strength is tested according to ISO 527-2 using injection-molded samples from weld line mold plates; and notched impact strength of simply supported beams is tested according to ISO 179-1 at 23°C.

[0041] The specific preparation methods and weight proportions of the embodiments and comparative examples are as follows:

[0042] (1) Dry the PC resin at 120℃ for 4-6 hours, the ABS resin at 80℃-90℃ for 2-3 hours, and the surface-modified flat glass fiber at 100℃-110℃ for 3-4 hours to remove moisture.

[0043] (2) First, weigh PC resin, ABS resin, compatibilizer, toughening agent, lubricant, carbon black and other additives according to the weight parts, and then homogenize them in a high-speed mixer to obtain mixed raw materials;

[0044] (3) The above mixed raw materials are placed in the main feed bin of the co-rotating twin-screw extruder, and the surface-modified flat glass fiber is placed in the side feed bin of the co-rotating twin-screw extruder. The fiber is then fed into the barrel of the extruder through the side feed screw. After melt extrusion, cooling, granulation and drying, a glass fiber reinforced PC / ABS composite material with high weld line strength is obtained.

[0045] Table 1. Parts by weight of Examples 1-3 and Comparative Examples 1-2

[0046]

[0047] Table 2 Performance test results of Examples 1-3 and Comparative Examples 1-2

[0048]

[0049]

[0050] The test results show that the weld line tensile strength of the modified materials in Examples 1-3 of this invention is above 52 MPa, the weld line strength retention rate is ≥82%, and the notched impact strength and processing fluidity are excellent. However, the weld line strength of Comparative Example 1 (single compatibilizer) and Comparative Example 2 (surface modified conventional glass fiber) is significantly reduced, with a retention rate of only 65%-71%. This proves that the formulation design and preparation method of this invention can effectively improve the weld line strength of PC / ABS materials.

[0051] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A glass fiber reinforced PC / ABS composite material with high weld line strength and a method for preparing the same, characterized in that, consists of the following weight parts: PC resin: 40-60 wt%; ABS resin: 25-45 wt%; Composite compatibilizer: 3-8 wt%; Surface modified flat glass fiber: 5-15 wt%; Toughening agent: 2-6 wt%; Lubricant: 0.2-0.5 wt%; Carbon black: 0.5 wt%; Other auxiliary agents 0.1-3 wt%.

2. The glass-fiber reinforced PC / ABS composite material with high weld line strength according to claim 1, characterized in that: The number average molecular weight of the PC resin is 2.2w-3w, and the melt flow rate (300℃ / 1.2kg) is 10-20g / 10min.

3. The high weld line strength glass fiber reinforced PC / ABS composite material according to claim 1, characterized in that: The acrylonitrile content of the ABS resin is 23-30 wt%, the butadiene content is 18-26 wt%, and the melt flow rate (220℃ / 10kg) is 15-25g / 10min.

4. The high-weld-line strength glass fiber reinforced PC / ABS composite material of claim 1, wherein: The composite compatibilizer is a combination of maleic anhydride grafted ABS (MAH-g-ABS) and styrene / acrylonitrile copolymer grafted glycidyl methacrylate (SAN-g-GMA), with a weight ratio of 1:0.5-1:

2.

5. The high-weld-line strength glass fiber reinforced PC / ABS composite material according to claim 1, characterized in that: The surface modified flat glass fiber is alkali-free short flat glass fiber treated with a silane coupling agent, with a flatness of 1.8-4.2% and a short glass fiber length of 1-3mm.

6. The high-weld-line strength glass fiber reinforced PC / ABS composite material of claim 1, wherein: The toughening agent is a methyl methacrylate-butadiene-styrene ternary copolymer (MBS) with a core-shell structure.

7. The high-weld-line strength glass fiber reinforced PC / ABS composite material according to claim 1, characterized in that: The lubricant is one of vinyl bis-stearamide (EBS) or pentaerythritol stearate (PETS) or a combination of the two.

8. The high-weld-line strength glass fiber reinforced PC / ABS composite material according to claim 1, characterized in that: The other auxiliary agents are primary antioxidants and secondary antioxidants, with the primary antioxidants being sulfur esters and the secondary antioxidants being phosphite esters.

9. The high-weld-line strength glass fiber reinforced PC / ABS composite material according to claim 1, characterized in that, The method comprises the following steps: (1) Dry the PC resin at 120℃ for 4-6h, the ABS resin at 80-90℃ for 2-3h, and the surface modified flat glass fiber at 100-110℃ for 3-4h to remove moisture; (2) First, weigh the PC resin, ABS resin, compatibilizer, toughening agent, lubricant, carbon black, and other auxiliary agents, and then homogenize them in a high-speed mixer to obtain a mixture of raw materials; (3) Place the above mixture of raw materials in the main feeding bin of a meshing co-rotating twin-screw extruder, and place the surface modified flat glass fiber in the side feeding bin of the meshing co-rotating twin-screw extruder, and then add it to the barrel of the extruder through the side feeding screw, and then melt extrude, cool, granulate, and dry to obtain a glass fiber reinforced PC / ABS composite material with high weld line strength.

Images