How to select the appropriate adhesive type, determine the dilution ratio, and specify the application thickness for the contraction sleeve bonding method with palm-to-palm contact
- PVC shrink sleeve labels (shrinkage rate ≤65%, suitable for flat beverage bottles): 1) Main adhesive types (industry-standard现货 options): 1. Economical high-speed welding adhesive (preferred): Brands: Beno BN-PVC01, Hecreat HC-508, Tianyang TY-PVC palm-adhesive (dichloromethane solvent-based); 2. Low-speed machine resin adhesive (for low-shrinkage applications): Model: NC nitrocellulose palm-adhesive HC-NC03.2) Dilution ratios (by weight): -Original solution: Special diluent = 100:15–30; -Diluent formula: 75% dichloromethane + 25% ethyl acetate; ⚠ Strictly avoid using cyclohexanone or DBE as strong solvents to prevent whitening of joints; -Viscosity control (25°C): 1200–2200 CPS; set to minimum value for high-speed machines, slightly thicker for low-speed machines. 3) Adhesive thickness and application amount: -Dry film thickness: **4–6 μm; -Wet adhesive application: 2.0–2 g/m² per side; -Joint width: 3–4 mm, applied only on single-side overlap surfaces; Key note: thinner adhesive layers are preferable; thickness>8 μm may cause hardening and thermal shrinkage cracking. 4) Process parameters: Initial curing time: 3–6 seconds; Application pressure: 0.3–0.5 MPa.
- PETG High-Shrinkage Labeling(Shrinkage Rate: 70%–80%; Suitable for irregular-shaped bottles; Most commonly used) Solution A: Solvent-based weakly soluble PU joint adhesive (90% used in factories) 1. Adhesive type (high elasticity, non-burst seam): Beno BN-PETG08, Ripu PUJ-C296, Songyu SY-G808 – Alcohol-soluble elastic PU adhesives 2. Dilution ratio (by weight): Original solution: Weak solvent diluent = 100:20–35; Diluent components: 78% 1,3-dioxane + 22% ethyl acetate (no strong ketone content; prevents PETG white fog formation); Viscosity: 1500–2500 cps (add more ethyl acetate for faster drying in summer; increase 1,3-dioxane proportion in winter) 3. Application specifications (critical): – Dry adhesive thickness: 5–8 μm (slightly thicker than PVC to ensure elasticity) – Wet adhesive application rate: 2.5–8 g/m² – Joint width: 3.5–4.5 mm – Excessive thinness may cause joint separation; excessive thickness may lead to hardening and shrinkage-induced chipping Solution B: High-speed line UV solvent-free elastic adhesive (for production lines exceeding 350 m/min) 1. Type: Jiamu JM311 or UV639 polyurethane-modified UV joint adhesive (high elongation resistance, no cracking) 2. No dilution required; apply directly from the original solution 3. Dry adhesive thickness: 6–9 μm; Application rate: 3.0–4.0 g/m² 4. Curing: Using a 365 nm LED UV lamp with light energy ≥ 1000 mJ/cm² for instant curing without re-adhesion
- Dual-function operation (the same production line alternates between manufacturing PVC and PETG): Standard adhesive: HC-UP110 – Universal alcohol-soluble PU bonding adhesive; 2. Dilution ratio: Original solution: Specialized alcohol ester diluent = 100:20; 3. Viscosity: 1800–2300 cps; 4. Uniform dry film thickness control: 5–7 μm; application rate: 2.3–3.5 g/m². Advantages: Non-corrosive to PVC, meets high-shrinkage elasticity requirements for PETG, and eliminates the need for tank cleaning.
- Additional parameters for OPS shrink film: 1. Adhesive: Modified weakly soluble PU adhesive SY-OPS66; 2. Dilution ratio: 100:18; 3. Film thickness after drying: 4–7 μ
- Standardized Application Procedures (to prevent blistering, whitening, and re-adhesion): 1. Environmental Temperature: 18–28°C; Humidity <65%. Reduce ethylene glycol proportion during humid conditions to prevent surface dryness and internal non-drying. 2. Application Method: Use a roller applicator with narrow gaps; avoid thick-layer application or excessive glue accumulation. 3. Product Inspection: After shrinkage in a 105°C steam oven, the adhesive joints shall show no cracks or whitening; when stored at room temperature for 3 days, there shall be no adhesion. 4. Food-grade labeling: Replace with halogen-free, environmentally friendly water-based PU bonding adhesive that exhibits no solvent volatilization and complies with national standards for beverage packaging.
- Simple Comparison Table| Film Material | Glue Type Reference | Base Solution: Diluent | Dry Glue Thickness | Wet Application Amount
Standard PVC | BN-PVC01 solvent-based adhesive | 100:15–30 | 4–6 μm | 2.0–3.2 g/m² |
PETG custom-shaped bottle | BN-PETG08 elastic PU | 100:20–35 | 5–8 μm | 2.5–3.8 g/m² |
PETG High-Speed Compound | JM311 UV-Elastic Adhesive | Undiluted base solution | 6–9 μm particle size | 3.0–4.0 g/m² |
Suitable for both PVC and PETG applications | HC-UP110 Universal PU | 100:20 composition ratio | 5–7 μm particle size | 2.3–3.5 g/m²
