Application of ASA Powder in Injection Molding

Abstract: A new type of powder used to improve the mechanical properties of AS resin such as impact resistance, increase the strength of the product and improve the aging performance of the product—ASA powder JCS-885, applied to AS resin injection molding. It is a product of core-shell emulsion polymerization and has good compatibility with AS resin. It can improve the mechanical properties of the product without reducing the aging performance of the product and is used in injection molding.
Keywords: AS resin, ASA powder, mechanical properties, weathering resistance, injection molding.
By: Zhang Shiqi, Shandong Jinchangshu New Material Technology Co., Ltd., Weifang, Shandong

1 Introduction

Generally, ASA resin, a terpolymer consisting of acrylate-styrene-acrylonitrile, is prepared by grafting styrene and acrylonitrile polymers into acrylic rubber and is commonly used in outdoor electronic parts, construction materials, and sporting goods due to its good properties, including weather resistance, chemical resistance, and workability. However, the use of ASA resins in materials requiring colors such as red, yellow, green, etc. is limited because the styrene and acrylonitrile compounds do not graft adequately into the acrylate rubber during its preparation and expose the acrylate rubber present therein, resulting in poor color matching and residual gloss. Specifically, the refractive indices of the monomers used to prepare the ASA resin were 1.460 for butyl acrylate, 1.518 for acrylonitrile, and 1.590 for styrene, such that there was a large difference between the refractive index of the acrylate rubber used as the core and the refractive index of the compounds grafted into it. Therefore, ASA resin has poor color matching properties. Since ASA resin is opaque and non-excellent mechanical properties such as impact properties and tensile strength of pure resin, this brings us to the current R&D direction and R&D route.

The common thermoplastic compositions currently available are acrylonitrile-butadiene-styrene (ABS) polymers joined with rubber as butadiene polymers. ABS polymers have excellent impact strength even at very low temperatures, but have poor weathering and aging resistance. Therefore, it is necessary to remove unsaturated ethylene polymers from graft copolymers in order to prepare resins with excellent impact strength along with excellent weathering and aging resistance.

The ASA powder JCS-885 developed by our company is more compatible with AS resin, and it has the advantages of high impact resistance, excellent processing performance, excellent weather resistance, and increased product strength. It is applied in AS resin injection molding.

2 Recommended Dosage

AS resin/ASA powder JCS-885=7/3, that is, for every 100 parts of AS resin alloy, it is composed of 70 parts of AS resin, and 30 parts of ASA powder JCS-885.

3 Performance comparison with domestic and foreign mainstream ASA powder

1. The AS resin alloy was prepared according to the formula in Table 1 below.

Table 1

Type Mass/g
AS Resin 280
ASA Powder JCS-885 120
Lubricating Formula 4
Compatibility Agent 2.4
Antioxidant 1.2

2. Processing steps of AS resin alloy: Compound the above formula, add the compound to the granulator for initial fusion of granules, and then put the granules into the injection molding machine for injection molding.
3. Test to compare the mechanical properties of the sample strips after injection molding.
4. The performance comparison between ASA powder JCS-885 and foreign samples is shown in Table 2 below.

Table 2

Item Test Method Experimental Conditions Unit Technical Index (JCS-885) Technical Index (Comparison Sample)
Vicat Softening Temperature GB/T 1633 B120 90.2 90.0
Tensile Strength GB/T 1040 10mm/min MPa 34 37
Tensile Elongation at Break GB/T 1040 10mm/min % 4.8 4.8
Bending Strength GB/T 9341 1mm/min MPa 57 63
Bending Modulus of Elasticity GB/T 9341 1mm/min GPa 2169 2189
Impact Strength GB/T 1843 1A KJ/m2 10.5 8.1
Shore Hardness GB/T 2411 Shore D 88 88

4 Conclusion

After experimental verification, the ASA powder JCS-885 developed by our company and AS resin injection molding, all aspects of mechanical properties have been improved, and in all aspects is not inferior to other powder at home and abroad.

Post time: Jun-18-2022