Selection Guide for Blow Film LLDPE with Pre-Blended Slip & Antiblock Additives: Full Introduction to SABIC 218WJ
Common Pain Points: Production Losses from Self-Blending Additives
Most film processors purchase unmodified base LLDPE and manually add slip agents and antiblock powders to improve film opening performance. This approach triggers multiple production defects:
Manual mixing cannot achieve uniform additive dispersion, causing uneven haze and unstable heat-seal strength. Powder dust contaminates extruder equipment and increases cleaning frequency. Slip agent dosage relies on empirical judgment — excessive amounts cause poor ink adhesion and weak seals; insufficient amounts lead to film adhesion and machine downtime during high-speed bag making.
Factory pre-blended additive LLDPE eliminates these troubles. This guide takes SABIC 218WJ, a mainstream butene copolymer grade, as the core case to explain complete selection criteria, parameter logic and practical processing tips for additive-containing film resins.
Four Core Selection Criteria for General Food & Industrial Film LLDPE
Copolymer Structure Determines Film Toughness
LLDPE is divided into butene, hexene and octene copolymer systems. Butene copolymer offers mature technology and wide market circulation, balancing production cost and low-temperature impact resistance for shopping bags, food storage bags and lightweight industrial liners. Hexene and octene long-chain grades deliver higher puncture resistance but carry higher costs, mainly for heavy-gauge films. SABIC 218WJ adopts butene copolymer structure, making it the mainstream choice for general packaging.
Additive Formulation Impacts High-Speed Line Efficiency
The industry standard additive ratio is 1500ppm slip agent and 3500ppm antiblock agent. Different manufacturers fine-tune slip within 1200–1800ppm and antiblock within 3000–4000ppm. 218WJ strictly follows this standard formula.
Insufficient additives cause film layer adhesion and frequent machine halts. Excessive additives migrate to the film surface, damaging ink adhesion and weakening heat-seal strength, generating defective products with leaking seals.
Slip agents also have a migration cycle: 218WJ uses erucamide-based slip agents. Films require 24–72 hours after extrusion for additives to fully migrate to the surface and form a lubricating layer. Newly produced films have temporarily high friction coefficients — manufacturers switching to this grade may misjudge its slip performance.
Optical Properties Match End-Use Requirements
Supermarket retail and fresh food packaging require low haze and high gloss; industrial liners and garbage bags allow relaxed optical standards. 218WJ offers haze of 13% (ASTM D-1003, typical; some batches range 13–15%) and 60° gloss of 80 (ASTM D-2457) — balanced optical performance satisfying both food display and industrial film needs.
Food Compliance Defines Application Scope
Films for direct food contact require complete food contact certification. Industrial liners and garbage bags can adopt looser standards. Formulated without TNPP stabilizers, 218WJ holds globally recognized food contact certificates, supporting both food packaging and general industrial packaging applications.
Universal benchmark parameters for film-grade LLDPE
Density: 0.918g/cm³ (ASTM D-1505)
Melt flow rate: 2.0g/10min (190°C/2.16kg, ASTM D-1238)
Vicat softening point: 98°C (ASTM D-1525, typical value)
Broad heat-sealing window, compatible with monolayer and multi-layer co-extrusion equipment
Core Performance & Application Scenarios of SABIC 218WJ
218WJ is a butene copolymer blow-film LLDPE from SABIC, factory pre-blended with standardized slip and antiblock agents — eliminating the need for processors to mix powders. This TNPP-free grade serves as a benchmark resin for mass production of general packaging among small and medium film manufacturers.
Key Performance Advantages
Balanced mechanical properties
Dart drop impact: 85g (ASTM D-1709, typical; supplier datasheets range 85–120g)
Elongation at break: MD 700%, TD 750% (ASTM D-882)
Elmendorf tear strength: MD 130g, TD 320g (ASTM D-1922)
Minimal deviation between MD and TD tensile/tear strengths — films resist rupture during filling and stacking. Stable ESCR performance suitable for long-term storage of grease and daily chemical solvents.
Stable processing performance
Uniform melt fluidity, low gel count, consistent additive distribution across batches — stable defect rate control during continuous mass production.
Wide application coverage
Food flexible packaging: fresh produce bags, freezer bags, composite food outer films
Civil packaging: supermarket shopping bags, household garbage bags
Industrial films: lightweight chemical liners, cargo wrapping films
Agricultural films: ground mulch films, greenhouse inner insulation films
Compared with unmodified base resins, 218WJ removes manual mixing, reduces powder dust pollution, and simplifies production workflow. It is ideal for film factories equipped with high-speed automatic bag making machines.
4. Standard Processing Guidelines for SABIC 218WJ
For monolayer and multi-layer co-extrusion production, follow these process control standards
Extruder barrel temperature: 185–205°C. Excessively high temperatures accelerate slip agent migration, weakening printing and heat-sealing performance. 218WJ features a TNPP-free formulation with optimized thermal stability, allowing higher processing temperatures without easy degradation. However, prolonged overheating should still be avoided to prevent excessive slip agent blooming.
Blow-up ratio: 2.0–3.0 — fine-tune according to film thickness and equipment; optimal thickness uniformity is achieved within this range.
Film thickness range: 15–80μm. For heavy-gauge films exceeding 80μm, co-blend with high-toughness hexene/octene LLDPE.
Industry standard co-blending ratios:
10%–30% LDPE to improve flexibility and heat-seal performance
5%–15% HDPE to increase stiffness
Actual ratios require small-scale trial production based on thickness, equipment and end-product requirements.
5. Selection Summary: Which Film Factories Are Suitable for 218WJ?
Factories with high-speed automatic bag making machines facing film adhesion and feeding issues
Manufacturers producing fresh food storage bags, supermarket shopping bags and lightweight industrial liners, requiring both transparency and production efficiency
Processors wanting to eliminate slip powder purchases and mixing stations, simplifying workflows and reducing labor and defect costs
Factories producing both food packaging and general industrial packaging, requiring full food contact compliance certificates
Before placing bulk orders for 218WJ, request the official complete technical datasheet and conduct small-batch trial production with your own extruder equipment. Test film haze, friction coefficient and heat-seal peel strength. Confirm all indicators match order requirements before mass purchasing.
