Application of Light Stabilizers in Plastic Product Production

Light stabilizer is the core anti-aging additive in plastic production. By absorbing, shielding or quenching ultraviolet energy, it can inhibit the molecular chain fracture and oxidative degradation of plastics caused by ultraviolet radiation, avoid discoloration, embrittlement and cracking of products in the later period, and extend the service life of outdoor and light environment. The addition of light stabilizer in plastic production (such as extrusion, injection molding, blow molding) can endow products with anti-aging performance from the source, solve the pain point of failure of products not added outdoor for 6 months, and adapt to almost all plastic categories such as PE, PP, PVC, PET, PC, etc. According to their mechanisms of action, they are divided into ultraviolet absorbers, quenchers, shielding agents, and free radical scavengers. Currently, they are developing towards high efficiency, low migration, and green multifunctional directions, which is the core support for the expansion of outdoor applications of plastic products.

1、 The core function logic of light stabilizers: blocking the aging source from the production end

Plastic molecular chains are easily damaged by 290-400nm ultraviolet radiation. Light stabilizers are blended with raw materials or processed in the later stage of production to build a full chain protection and avoid aging problems from burying hidden dangers in the production process

Production adaptability: Compatible with mainstream plastic production processes such as extrusion, injection molding, blow molding, and rolling, with heat resistance covering processing temperatures of 150-320 ℃, without affecting product formability;

Protection pathway: UV absorbers (such as UV-327) absorb light energy and convert it into heat energy, free radical scavengers (such as HALS 944) terminate the degradation chain reaction, shielding agents (such as carbon black) physically block UV radiation, and quenching agents (such as nickel complexes) transfer excited state energy;

Core value: Adding during the production stage can extend the outdoor life of plastic from a few months to 3-10 years, while ensuring the mechanical properties and appearance stability of the product, and reducing the cost of replacement in the later stage.

2、 Types and production adaptability of mainstream light stabilizers

Different light stabilizers have significant differences in heat resistance, compatibility, and transparency, and should be selected based on the type of plastic, production process, and product use

1. UV absorbers: preferred for transparent product production

Representative products: Benzotriazole (UV-327, UV-326), Benzophenone (UV-531);

Adaptation process: injection molding, blow molding, extrusion, heat-resistant temperature 180-280 ℃;

Compatible plastics: PET, PC, PP transparent grade, PVC transparent film;

Production scenario: PET beverage bottle blow molding, PC lampshade injection molding, PP transparent lunch box production, without affecting product transparency (retention rate>90%).

2. Hindered amine light stabilizers (HALS): the mainstay of long-term protection

Representative products: Low molecular weight (HALS 770), high molecular weight (HALS 944);

Adaptation process: All plastic production processes, heat-resistant temperature 160-300 ℃;

Suitable for plastics: PE, PP, PVC, ABS;

Production scenarios: PE agricultural film extrusion, PP car bumper injection molding, PVC door and window profile production, outdoor protection period can reach 5-10 years.

3. Shielding agent: Suitable for low-cost opaque products

Representative products: carbon black, nano TiO ₂ ZnO；

Adaptation process: extrusion, injection molding, heat-resistant temperature 150-250 ℃;

Suitable for plastics: PE water supply pipes, PVC pipes, PP outdoor trash cans;

Production scenario: Extrusion of black PE drip irrigation pipes and production of dark PVC drainage pipes, with low cost and direct protection.

4. Quenching agent: specialized for dark colored products

Representative product: Nickel complex (UV-1084);

Adaptation process: injection molding, extrusion, heat-resistant temperature 160-200 ℃;

Compatible with plastics: PP, PE dark grade, ABS black parts;

Production scenario: Injection molding of black PP automotive parts, production of dark PE outdoor products, with strong weather resistance but not suitable for transparent products.

3、 Application Practice in Key Plastic Product Production

1. Production of polyolefin products (PE, PP)

PE agricultural film extrusion:

Formula: PE raw material+0.2% UV-327+0.3% HALS 770+0.15% antioxidant 1010;

Process: Extrusion temperature 150-180 ℃, inflation ratio 2.5-3.0;

Effect: After 12 months of outdoor use, the light transmittance is greater than 85%, the tensile strength retention rate is greater than 70%, and there is no brittle fracture.

PP car bumper injection molding:

Formula: PP raw material+0.5% HALS 944+0.2% UV-531+0.2% antioxidant 168;

Process: Injection molding temperature 180-200 ℃, mold temperature 50-60 ℃;

Effect: Outdoor for 3 years without discoloration or cracks, with a retention rate of impact strength greater than 80%.

2. Production of engineering plastic products (PET, PC)

PET beverage bottle blow molding:

Formula: PET raw material+0.15% UV-326+0.2% antioxidant 1010;

Process: Drying temperature of 160 ℃, blow molding temperature of 270-280 ℃;

Effect: Block UV rays, prevent beverage spoilage, and the bottle body remains yellow for 6 months.

PC outdoor lampshade injection molding:

Formula: PC raw material+0.3% UV-327+0.4% HALS 944;

Process: Injection molding temperature 280-300 ℃, holding time 15-20 seconds;

Effect: Outdoor light transmittance>80% for 5 years, no cracking or discoloration.

3. Production of building materials and plastic products (PVC, PE)

Extrusion of PVC door and window profiles:

Formula: PVC resin+2% carbon black+0.3% UV-531+2% calcium zinc heat stabilizer;

Process: Extrusion temperature 150-170 ℃, traction speed 5-8m/min;

Effect: There is no significant aging for 10 years outdoors, and the retention rate of tensile strength is greater than 65%.

PE water supply pipe extrusion:

Formula: PE raw material+0.6% HALS 944+3% carbon black+0.2% antioxidant 1010;

Process: Extrusion temperature 160-180 ℃, pressure 10-15MPa;

Effect: The outdoor section is UV resistant, the buried section is corrosion-resistant, and the service life is up to 50 years.

4. Production of food contact plastics (PP, PET)

PP microwave lunch box injection molding:

Formula: PP raw material+0.1% UV-327+0.1% antioxidant 1010;

Process: Injection molding temperature 170-190 ℃, cooling time 10-15 seconds;

Effect: Migration rate<0.01mg/kg, in line with food grade standards, resistant to light without aging.

4、 Application Challenges and Development Trends

1. Existing challenges

Compatibility issue: Some light stabilizers have poor compatibility with plastics, which can easily precipitate and cause the surface of the product to become sticky and foggy;

Cost effectiveness balance: Efficient light stabilizers (such as high molecular weight HALS) have high costs and are difficult to meet long-term needs at low dosages;

Environmental compliance pressure: Some nickel complexes and halogen containing light stabilizers do not comply with EU REACH and other environmental standards.

2. Development Trends

Efficient and low migration: Developing high molecular weight, reactive light stabilizers to reduce migration and precipitation during production and use, suitable for high-end scenarios;

Biobased: Developing biodegradable and low toxicity light stabilizers using rosemary extract and tea polyphenol derivatives as raw materials, in line with the dual carbon policy;

Multi functional integration: Developing "light stable+antioxidant+anti-static" composite additives, simplifying production formulas, and reducing processing costs.

5、 Summary

Light stabilizers, through precise addition during the production stage, build UV protection barriers for plastic products from the source. They are indispensable additives for plastic products in outdoor and light environments. It is compatible with various plastic production processes, and through type selection and formula optimization, it can balance the weather resistance, appearance, and safety of products. In the future, with breakthroughs in efficient and green technologies, light stabilizers will further support the high-end and long-term development of plastic products, and expand more outdoor application scenarios.