Cailong

A pouch that looks normal after filling can become visibly swollen during air transport. Buyers considering BOPP SiOx Film need to separate two questions: how the film limits oxygen and moisture transmission, and how a sealed package responds when external pressure changes. A low transmission result does not establish that the pouch, seals and outer carton can accommodate expanding headspace.

The transparent barrier products in Cailong's film portfolio provide material options for packaging development. For an air freight project, the useful starting point is the actual filled pack and route. Record whether expansion occurs only in transit, remains after arrival, or develops progressively in storage. Those observations help distinguish a pressure response from other causes that require a separate investigation.

Why a barrier pouch can still expand

Gas enclosed during filling remains part of the package. When surrounding pressure falls, that gas can occupy more volume if the pouch can move. The resulting shape depends on available headspace, film flexibility, restraint from the product and carton, and the package construction. Oxygen barrier describes transmission through a material under defined conditions; it is not a measure of resistance to this outward loading.

Do not conclude that swelling proves excessive oxygen entry. Equally, do not dismiss an expanding package simply because the incoming film met its OTR requirement. A package can retain its contents while developing deformation that interferes with stacking, presentation or seal reliability. The investigation needs evidence about the pack's response, rather than an immediate change to a lower OTR film.

Give each layer a defined job

Cailong lists its BOPP SiOx material as a transparent barrier film. The supplied TZ technical sheet identifies BOPP / BOPP SiOx / RCPP as a recommended laminate construction. This is a material arrangement for evaluation, with an outer BOPP layer, a coated barrier component and a sealing component. It is not a declaration that every pouch using those layer names is suitable for air freight.

The same sheet describes a retort condition of 121°C for 30 minutes. That condition concerns a thermal process and cannot be converted into an altitude or pressure rating. Keep thermal processing, barrier performance and transportation loading as separate requirements. The selected adhesive system, layer thicknesses and package dimensions must be specified before any comparison becomes meaningful.

Start with headspace and geometry

Two pouches made from the same laminate can respond differently if their fill volumes or shapes differ. Record the amount and type of gas introduced, product quantity, pouch dimensions, gussets and the position of rigid product features. A wide unsupported panel may visibly move before another part of the package. Expansion can also change how adjacent packs press against each other inside a carton.

Avoid reducing headspace without checking the filling process and product requirements. A nominal volume written on a drawing may not describe the gas present in production packs. Compare samples prepared on the intended equipment, with the normal filling variation represented. If a flushing process is used, its gas composition and residual gas volume belong in the sample record.

Evaluate seals under outward loading

Seal strength measured on a narrow strip answers a different question from the behavior of a complete expanding pouch. During pressure exposure, corners, transitions and local contamination can influence where loading concentrates. Review these areas on filled samples. Observe whether the seal opens, stretches, channels or remains intact while the pouch body changes shape.

For a useful investigation, retain unexposed controls and examine samples before and after the agreed pressure cycle. Record the pressure profile, hold periods, temperature, orientation and packaging restraint. Use conditions established for the intended distribution route and customer requirement. There is no universal chamber setting in the film information that can replace that route-specific decision.

Keep the carton in the trial

A loose laboratory pouch does not reproduce every contact inside a shipping case. Carton fit, dividers, stacking and neighboring packs can limit movement or create contact points. Run the agreed comparison with the intended secondary packaging as well as any isolated pouch specimens needed for diagnosis. Document the difference between cosmetic bulging and actual loss of package integrity.

After exposure, assess the outcomes that matter to the product. These may include leakage, seal continuity, visible distortion and retained barrier performance. Select suitable methods with the packaging laboratory. An unchanged visual appearance cannot establish unchanged transmission, and a transmission result alone cannot confirm an intact seal around the entire pouch perimeter.

Decide what actually needs to change

If the barrier remains adequate but the package cannot accommodate expansion, the improvement may involve headspace control, pouch dimensions, seal design or secondary packaging. If converted samples lose barrier after the transport simulation, investigate the coating and laminate response as well. Keeping these failure modes separate makes the next material trial more informative and avoids solving the wrong problem.

A change from an opaque barrier structure to transparent BOPP SiOx may be considered when product visibility matters. Maintain the same distribution requirements during that comparison. Transparency and a PP-based material direction do not remove the need to qualify the complete construction. Any recycling statement also requires its own evidence for the actual laminate and intended market.

Information to send with a sample request

Provide Cailong with the current layer construction, filled pouch dimensions, product type, filling conditions and the route-related problem. Include photographs at the point where swelling is observed and identify whether the product or only empty pouches has been tested. Request the specification for the particular supplied film rather than relying on a general product category.

The objective is a pack that combines the required product protection with acceptable behavior in distribution. BOPP SiOx can be evaluated for its transparent barrier role, while pressure resistance is established on the filled package. Approving those two functions with separate evidence gives purchasing and packaging teams a clearer basis for selecting the material.