| HS Code | 788826 |
| Product Name | TianjinSunray Transparent cross-linked EVA interlayer Film |
| Manufacturer | Tianjin Sunray |
| Material | Ethylene-vinyl acetate copolymer |
| Appearance | Transparent film |
| Color | Clear |
| Thickness | 0.38 mm, 0.76 mm, 1.14 mm, 1.52 mm |
| Width | 1000 mm to 2500 mm |
| Density | 0.92-0.95 g/cm³ |
| Cross Linking Degree | ≥75% |
| Light Transmittance | ≥90% |
| Haze | ≤1.0% |
| Tensile Strength | ≥18 MPa |
| Elongation At Break | ≥500% |
| Peel Adhesion To Glass | ≥40 N/cm |
| Water Absorption | ≤0.1% |
| Softening Point | 70-80°C |
| Thermal Shrinkage | ≤3% |
| Uv Resistance | High |
| Weather Resistance | Excellent |
| Storage Conditions | Cool, dry, avoid direct sunlight, below 30°C |
| Shelf Life | 12 months |
| Application | Laminated glass, architectural glass, automotive glass, photovoltaic modules |
As an accredited TianjinSunray Transparent cross-linked EVA interlayer Film factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
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In conventional 60-cell and 72-cell crystalline silicon module construction, the TianjinSunray transparent cross-linked EVA interlayer film is positioned as both the front-side encapsulant and the rear-side bonding layer. The basic layup is 3.2 mm tempered low-iron soda-lime glass / 0.45 mm to 0.55 mm EVA / cell matrix / 0.45 mm to 0.65 mm EVA / backsheet. The film is cut with an edge offset of 2 mm to 5 mm beyond the cell perimeter to permit controlled melt flow without extrusion into the laminate perimeter. Lamination is performed on a dual-chamber oil-heated membrane laminator with platen temperature uniformity of ±1.5 K. The vacuum sequence pulls to -90 kPa to -100 kPa gauge before the platen temperature is raised. Peak laminate temperature is held at 145 °C to 155 °C for 8 min to 15 min. Under these conditions, peroxide decomposition produces a final gel content of 80 % to 90 % as measured by ASTM D2765. Crosslink density directly controls post-lamination creep and adhesion retention. Under-cure below 70 % gel content produces edge delamination at busbar crossings after thermal cycling. Over-cure above 95 % shifts the film into a brittle regime and raises yellowness index. The processed module is qualified under IEC 61215-1 and IEC 61730-2. Damp-heat exposure is conducted at 85 °C and 85 % RH for 1000 h per IEC 61215-2. Humidity-freeze cycling is performed under IEC 61215-2 as well. In production, moisture uptake above 0.1 % by film weight causes bubble formation during lamination. Pre-drying at 40 °C to 50 °C for 4 h to 8 h is required if storage relative humidity exceeds 60 % RH. The terminal products are framed utility-scale PV modules and distributed-generation roof modules. The main bottleneck on the line is the timing of vacuum release. The membrane must remain under vacuum until the EVA network reaches sufficient gel structure. Premature release before the gel point allows entrapped air to expand at cell edges.
Overhead glazing laminates using EVA are processed without an autoclave, which changes the lamination envelope relative to plasticized PVB. A typical glass package is 6 mm to 10 mm heat-strengthened top glass / 0.76 mm or 1.52 mm EVA / 6 mm to 10 mm heat-strengthened bottom glass. The stack is placed in a vacuum bag oven with vacuum held at -80 kPa to -95 kPa gauge under atmospheric membrane pressure. Heating is ramped at 5 K/min to 8 K/min until the glass surface reaches 140 °C to 150 °C. Dwell is held for 20 min to 35 min. This temperature window is narrow. If the peak temperature falls below 135 °C, final gel content measured by ASTM D2765 remains below 70 % and the interlayer exhibits edge creep at 50 °C under long-duration dead load. If the peak temperature exceeds 158 °C, volatile by-products from the peroxide cure are released faster than the vacuum bag can extract them, producing microvoids along the glass interface. The cured EVA interlayer does not require autoclave pressure for bubble dissolution. Conformity for laminated safety glass is evaluated under ISO 12543-2 and impact behavior under EN 12600. Overhead installations are also assessed for glass strength using ASTM E1300 and for residual load-bearing capacity after breakage. EVA’s lower shear modulus at 50 °C compared with PVB means that unsupported glass panels with high slenderness ratios require a thicker interlayer or closer point fixings. The terminal products are skylights, canopies, sloped facades, and horizontal glass roofs. The main production failure mode is edge displacement during lamination when the glass sheets are not pinned at the corners. Edge alignment must be maintained with stainless steel fixtures because the low melt viscosity of EVA at 110 °C to 130 °C allows the interlayer to extrude under uneven bag pressure.
| Parameter | Backsheet c-Si PV | Overhead laminated glass | Glass-glass bifacial PV | Security anti-spall |
|---|---|---|---|---|
| Peak laminate temperature | 145–155 °C | 140–150 °C | 138–145 °C | 128–135 °C |
| Dwell at peak | 8–15 min | 20–35 min | 10–18 min | 20–35 min |
| Vacuum level | -90 to -100 kPa | -80 to -95 kPa | -90 to -100 kPa | -80 to -95 kPa |
| Final gel content | 80–90 % | 70–85 % | 75–85 % | 70–80 % |
| Governing standard | IEC 61215-1 | ISO 12543-2 / EN 12600 | IEC 61215-2 | EN 356 / ISO 16933 |
During dual-glass bifacial module production, the same EVA interlayer is used symmetrically on both sides of the cell plane, replacing a polyester backsheet with 2.0 mm or 2.5 mm heat-tempered glass. The stack becomes glass / EVA / cell plane / EVA / glass. The two sheets of glass approximately double the thermal mass compared with a backsheet module, so the platen setpoint is reduced by 5 K to 10 K and the dwell is extended by 2 min to 4 min. Peak laminate temperature is controlled to 138 °C to 145 °C to avoid glass warpage. Final gel content is set at 75 % to 85 % per ASTM D2765, which is sufficient for adhesion retention but leaves a small thermoplastic fraction that assists stress relaxation during thermal cycling. Vacuum level is maintained at -90 kPa to -100 kPa gauge. The main process defect is cell displacement. The EVA melt viscosity drops sharply between 110 °C and 130 °C, allowing the cell matrix to float if the glass is not restrained. Cell position is fixed with edge tape or a perforated stainless steel fixture. The perimeter of a glass-glass module is a direct moisture ingress path along the exposed EVA edge. A polyisobutylene edge seal or framed silicone seal is required for long-duration damp-heat performance. The completed module is tested under IEC 61215-2 damp-heat, humidity-freeze, and thermal-cycling sequences. Optical transmission through the transparent rear side is evaluated using ASTM E313 yellowness index after 1000 h damp heat. Terminal products include BIPV facade panels, balcony modules, carport modules, and agrivoltaic systems where rear-side light collection is required. On production-scale laminators, bubble formation at the cell gaps is the most common rear-side defect. The bubble source is residual moisture desorbing from the glass at temperatures above 120 °C. Pre-drying of the glass at 60 °C to 80 °C for 10 min before layup reduces the failure rate.
Security glazing with spall containment uses the EVA interlayer to bond tempered or chemically strengthened glass to polycarbonate or PET anti-spall sheets. A representative stack is 6 mm tempered glass / 0.76 mm EVA / 0.25 mm PET / 0.76 mm EVA / 4 mm soda-lime glass or 4 mm polycarbonate. The function of the EVA is not only adhesion but also energy transfer across the laminate. Lamination is performed in a vacuum bag at a lower peak temperature of 128 °C to 135 °C because polycarbonate undergoes dimensional distortion above 140 °C. The dwell is extended to 20 min to 35 min to achieve a gel content of 70 % to 80 % per ASTM D2765. Cooling is rate-controlled at ≤3 K/min to avoid optical waviness in the polycarbonate layer. Adhesion to polycarbonate requires corona pre-treatment to a surface energy of at least 38 mN/m, measured with dyne test inks. Without pre-treatment, edge delamination appears within 48 h of lamination. The completed laminate is tested under EN 356 for manual attack resistance and EN 12600 for impact safety. Blast-resistant configurations are evaluated under ISO 16933. Published data for EVA-specific anti-spall configurations is limited, so project-specific testing is mandatory before specification. The terminal products are ground-floor facades, safe rooms, blast-resistant windows, and hurricane-impact glazing. The main production failure mode is residual air trapped between the PET sheet and the EVA layer. This is controlled by introducing a 30 min vacuum soak at 90 °C before the temperature is raised above the film melt point.
Interior decorative lamination uses the transparent cross-linked EVA interlayer to encapsulate fabrics, printed PET films, wood veneer, wire mesh, and perforated metal sheets between two or more glass panes. A typical layup is 4 mm or 5 mm low-iron glass / 0.38 mm or 0.76 mm EVA / decorative insert / 0.38 mm or 0.76 mm EVA / 4 mm or 5 mm low-iron glass. The stack is processed in a vacuum bag laminator at 120 °C to 140 °C. The lower temperature is used for printed PET and wood veneer because these inserts release volatile compounds above 150 °C. The dwell time is 30 min to 60 min, longer than PV or architectural glass lamination, because the insert acts as a thermal insulator and slows the EVA cure front. Final gel content is 65 % to 80 % per ASTM D2765. This range is selected to retain some thermoplastic character for post-lamination trimming and edge polishing. Organic inserts are pre-dried at 50 °C for 6 h to 12 h until moisture content is below 0.5 % by weight. The absence of autoclave pressure prevents fabric distortion and metal mesh crushing. Fire performance of the finished panel is assessed under EN 13501-1 for reaction to fire. The terminal products are interior partitions, door panels, table surfaces, backsplashes, and elevator cab linings. The main defect is optical haze at the EVA-insert boundary. Haze is controlled by using clear EVA with a melt flow index below 20 g/10 min at 190 °C and 2.16 kg per ISO 1133-1, which limits flow-induced orientation at the insert surface.
Thick load-bearing glass laminates for floors, stairs, and balustrades use multiple EVA interlayers to bond glass plies and polycarbonate backing sheets. A representative structural stack is 10 mm tempered glass / 1.52 mm EVA / 10 mm tempered glass / 1.52 mm EVA / 6 mm polycarbonate. The laminate is assembled with the same vacuum bag technique, but the heating ramp is reduced to 2 K/min to 4 K/min because the thick glass stack develops temperature gradients across its thickness. Dwell at peak temperature is extended to 40 min to 70 min to allow the mid-plane EVA to reach gel content above 75 % per ASTM D2765. Cooling is strictly controlled at ≤2 K/min from 140 °C to 40 °C to minimize residual stress. Edge stress is checked with a polarimeter; values above 6 MPa cause post-installation edge cracking. Structural laminated glass with EVA is assessed under ASTM E1300 for glass strength and EN 1991 load combinations. Interlayer shear transfer is ignored in the conservative design method described in ISO 12543-1. Terminal products include glass floors, stair treads, balustrades, and swimming pool enclosures. The main production failure mode is delamination at the glass-polycarbonate interface caused by unequal thermal expansion. This is controlled by priming the polycarbonate surface and by maintaining ambient relative humidity below 50 % RH during layup. The EVA film should not be combined with amine-based sealants or cleaning agents. Amine compounds attack the adhesion promoter and reduce peel strength by more than 30 % in edge-exposed laminates.
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TianjinSunray Transparent cross-linked EVA interlayer Film is a peroxide-cured ethylene-vinyl acetate copolymer sheet supplied in roll form for safety-glass lamination and photovoltaic encapsulation. The product descriptor does not use a conventional alphanumeric model code; procurement documentation identifies the grade by nominal thickness, roll width, and post-lamination gel-content class. Common thicknesses are 0.25 mm, 0.38 mm, 0.50 mm, and 0.76 mm, with roll widths up to 2200 mm. Typical roll lengths are 100–200 m depending on thickness and core type. The compound is formulated with a vinyl acetate co-monomer fraction of 28–33 wt%, a dialkyl peroxide crosslinking initiator, a silane coupling agent, and UV/thermal stabilisers. The transparent cross-linked architecture is intended to form a three-dimensional network during lamination, suppressing cold flow above the melting range and improving creep resistance compared with uncross-linked thermoplastic EVA.
In service, the material acts as both optical coupling medium and structural adhesive. In glass-glass photovoltaic modules, it bonds front glass, cell strings, and rear glass or backsheet; in safety glazing, it contributes to glass fragment retention after impact. Because the network is thermosetting, the layer does not remelt during short-term temperature excursions to 90°C. The material remains more compliant than ionomer interlayers and provides less penetration resistance at equal thickness, which restricts its use in severe forced-entry or ballistic glazing without additional glass or polycarbonate layers.
Incoming film and post-lamination acceptance criteria are evaluated using the methods below. Values are representative of supplier-controlled data for transparent cross-linked EVA interlayers; published data for this specific TianjinSunray configuration may vary by batch and should be confirmed against the shipping certificate.
| Property | Test method | Acceptance range |
|---|---|---|
| Nominal thickness | ISO 4593 | 0.25–0.76 mm; tolerance ±0.03 mm |
| Density | ISO 1183-1:2019 | 0.94–0.96 g/cm³ |
| Total luminous transmittance, film-only | ASTM D1003-21 | ≥91% at 0.38 mm |
| Haze | ASTM D1003-21 | ≤1.5% |
| Yellowness index | ASTM E313-20 | ≤1.0 |
| Tensile strength at break, post-cure | ISO 527-3:2018 | 12–18 MPa |
| Elongation at break, post-cure | ISO 527-3:2018 | 400–600% |
| Gel content after cure | ASTM D2765-16 Method A | ≥70% after 145°C / 15 min |
| Melt flow rate, pre-cure | ISO 1133-1:2022 | 20–60 g/10 min at 190°C / 2.16 kg |
| Water absorption | ISO 62:2008, 24 h / 23°C | ≤0.5% |
| Glass peel adhesion, post-cure | ASTM D903-98 | ≥40 N/15 mm |
Glass adhesion after cure is commonly specified for photovoltaic applications as a minimum 180° peel strength of 40 N/15 mm when tested according to ASTM D903-98 on 10 mm wide specimens. Silane-containing EVA grades frequently reach 50–80 N/15 mm on clean float glass after damp-heat aging for 1000 h, but published data for TianjinSunray Transparent Cross-linked EVA Interlayer Film on all glass coatings and backsheet combinations is limited. Low-iron patterned PV glass can reduce adhesion by 20–30% relative to unpatterned float glass because the effective contact area at the interface is reduced.
Cross-linked EVA processes at lower moisture-control intensity than PVB and bonds to unprimed polycarbonate and PET. PVB is generally selected for automotive windshields where its plasticized glass transition near 25–30°C provides viscoelastic damping and established penetration resistance. EVA has a lower glass transition near -30°C and remains ductile at low temperatures; however, its tensile modulus is lower than ionomer. The comparative ranges below are representative of published interlayer property ranges, not supplier warranties.
| Parameter | Method | TianjinSunray cross-linked EVA | PVB | Ionomer |
|---|---|---|---|---|
| Tensile storage modulus at 25°C, 1 Hz | ISO 6721-1:2019 | 10–20 MPa | 3–10 MPa | 200–400 MPa |
| Glass transition region, tan δ peak | ISO 6721-1:2019 | -30 to -15°C | 25–30°C | 40–60°C |
| Equilibrium moisture content at 23°C/50% RH | ISO 62:2008 | ≤0.1 wt% | 0.4–0.6 wt% | ≤0.1 wt% |
| Post-lamination gel content | ASTM D2765-16 | ≥70% | no chemical gel | ionic network, no extractable gel |
| Adhesion to unprimed polycarbonate | Qualitative | high | low | moderate |
| Processing moisture limit | Production practice | ≤60% RH short layup | 23°C/28% RH conditioned | dry-handling recommended |
PVB requires controlled moisture because its adhesion to glass is highest near 0.4 wt% water content and falls if the sheet is too dry or too wet. EVA does not rely on water for glass adhesion; silane coupling forms siloxane bridges with glass-surface silanol groups. This permits EVA layup in clean-room conditions at up to 60% RH for short windows, though extended exposure above 70% RH generates interfacial bubble defects during heating as moisture desorbs.
Ionomer interlayers provide higher modulus and superior tear strength for hurricane-resistant glazing and structural balustrades. They require higher processing temperatures and dry handling. Cross-linked EVA processes at 130–150°C, compatible with standard PV vacuum laminators and many autoclave-capable glass lines. Compared with aliphatic TPU interlayers, cross-linked EVA provides higher optical clarity at lower cost and lower processing temperature; TPU is preferred where very high impact toughness and polycarbonate adhesion are critical. Uncross-linked EVA flows above 70–80°C, causing edge flow and reduced damp-heat stability. The cross-linked form maintains shape above the crystalline melting point and resists creep at module operating temperatures up to 85°C.
Thermal crosslinking of EVA interlayer film is the critical control point. The dialkyl peroxide initiator commonly used in EVA encapsulant compounds has a 10-hour half-life temperature in the range of 115–120°C and a 1-minute half-life near 165–170°C. At a lamination plateau of 145–150°C, gel content rises to ≥70% within 12–18 min. If the glass or module surface temperature does not exceed 138°C for at least 10 min, extraction testing per ASTM D2765-16 may show gel content below 60%. Under-cured film exhibits edge creep, lower glass adhesion, and early delamination in damp-heat aging.
Temperature mapping on flat-plate vacuum laminators with heated platen sizes of 2200 mm × 3600 mm has recorded 6–8°C edge-to-centre differences during the first 5 min of the plateau. The result is a non-uniform crosslink density across the laminate unless the cycle is extended or edge zones are compensated. In silicone-membrane laminators, increasing membrane thickness from 3 mm to 5 mm can require 3–5 min additional time for core temperature equilibrium. A three-stage vacuum profile is commonly used for photovoltaic laminates: cold evacuation at 25–60°C for 3–5 min, heating to 145°C under vacuum below 3 mbar, and a final consolidation ramp of 50–80 kPa above the membrane. If vacuum is released too early or diaphragm pressure is applied below 60 kPa, gas bubbles remain at the glass-interlayer interface.
For safety-glass autoclaving, the recommended sequence is vacuum bag de-airing at 80–110°C for 10–20 min, followed by autoclave exposure at 130–140°C and 12–14 bar for 30–60 min. Pressure suppresses bubble growth while the EVA network cures. Post-cure gel content should be checked on production samples per ASTM D2765-16, not inferred from platen or autoclave setpoint alone. In hot climates, container or warehouse temperatures above 30°C may reduce available peroxide over extended storage and shift gel content; pallets should be stacked no more than 2 high and stored upright.
The film should be stored in the original sealed packaging at 5–25°C, protected from direct sunlight and strong UV sources. If the roll is removed from packaging in a clean room at 23°C and 50% RH, the layup window is typically 8 h; at 60% RH, the window shortens to 4 h. Moisture uptake above 0.4 wt% during storage or unwrapped layup can produce interfacial bubbles during lamination because water vapour desorbs at 100–140°C and is trapped before full crosslinking. Conditioning at 40°C for 4 h in a dehumidifying oven reduces surface moisture; conditioning above 60°C should be avoided because premature peroxide decomposition and roll blocking may occur.
Incoming slitting should use rotary shear or razor slitting with dust extraction. Slitting dust generated from EVA film is a known cause of optical defects after lamination; if slit edges show white dust or fibre formation, blade speed and sharpness must be corrected before layup. The slit roll should be re-inspected for contamination using dark-field inspection at 800 lux. Fisheyes, gels, or thickness bands larger than 0.5 mm in diameter are not acceptable for architectural safety glass. For photovoltaic use, defect tolerance may be relaxed outside the cell active area, but contamination within the cell string area increases the risk of microbubble formation. Glass surfaces should be cleaned with low-residue detergent and rinsed to conductivity below 5 µS/cm before layup. Do not bring the film into contact with copper stearate, amine-based slip additives, or solvent-based cleaning agents; these can alter peroxide decomposition or silane coupling kinetics.
Qualification of a cross-linked EVA interlayer in a photovoltaic module is not complete without damp-heat, humidity-freeze, and UV exposure. Damp-heat testing at 85°C and 85% RH for 1000 h per IEC 61215-1:2021 MQT 13 is the primary screen for adhesion loss and yellowing. Modules using EVA encapsulants can develop a yellowness-index increase of 1.0–3.0 after 1000 h depending on stabilizer package and cure level; transparent grades with low free-peroxide residues generally exhibit less colour shift.
Humidity-freeze cycling per IEC 61215-1:2021 MQT 12 alternates between 85°C/85% RH and -40°C. The resulting interfacial tensile stress can initiate edge delamination if adhesion drops below 40 N/15 mm. Cross-linked EVA with gel content above 70% and clean glass surfaces typically retains adhesion after 10 humidity-freeze cycles; published data for this specific TianjinSunray configuration on all glass types and backsheet combinations remains limited. For safety glazing, impact performance is evaluated under EN 12600 or ANSI Z97.1; the interlayer contributes to retained fragment adhesion rather than providing all penetration resistance in thick multi-layer laminates.
Xenon-arc weathering per ISO 4892-2:2013 with 0.35 W/m² at 340 nm and black-standard temperature 65°C is used to assess UV stability. Transparent EVA interlayer film should maintain yellowness index below 2.0 and haze below 3.0% after 1000 h of exposure when the outer glass contains a UV filter. Without a UV-filtering outer glass layer, degradation kinetics accelerate, and the film is not suitable as an exposed surface. Regulatory documentation for the transparent grade should confirm compliance with RoHS 2011/65/EU Annex II restricted substances and REACH EC 1907/2006 Article 33 SVHC communication; photovoltaic qualification is performed at the module level under IEC 61215-1:2021 and IEC 61730-2:2016, not as a standalone certified component.
