Will paper cups deform or leak at high temperatures?

1. Dual Protection of Structure and Materials Most modern disposable paper cups use a PHA coating or other biodegradable plastic film as the inner layer. This coating has excellent barrier properties, maintaining the integrity of the cup wall in hot beverage environments around 90℃, preventing liquid penetration and significantly reducing the risk of deformation due to thermal expansion and contraction.

2. Actual Test Results Industry standards rigorously test the leakage performance of paper cups: hot water at 90℃±5℃ is poured into the cup, and after standing for 30 minutes, it is checked for any signs of leakage. If no leakage is found in any of the 5 samples, the cup is considered to meet the requirements for hot beverage use. Most paper cups that meet this standard maintain their shape and do not leak in actual use.

Why does a plastic coating need to be added inside the paper cup?

1. Preventing Penetration and Repelling Liquid Paper pulp itself is absorbent; direct contact with liquid can cause the paper to soften and crack. The internal plastic coating forms a non-porous barrier layer, preventing liquids from penetrating the paper base and thus preventing leakage from the cup walls and bottom. Patent documents explicitly state that using non-toxic, high-temperature resistant plastics (such as PE, PSU, PES, etc.) for both the inner and outer membranes achieves this anti-leakage function.

2. Enhanced Heat Resistance: The plastic coating provides additional mechanical support in hot beverage environments, preventing the paper cup from deforming due to thermal expansion. Experimental data on the PHA coating shows that it maintains its barrier properties at high temperatures, significantly improving the heat resistance of the paper cup, allowing it to safely hold beverages such as coffee and hot tea.

3. Maintaining Appearance and Hygiene: The coating prevents staining, odors, and bacterial growth caused by liquid seeping into the paper layer, ensuring the cup's hygiene and safety during use.

4. Recyclable and Environmentally Friendly: With the use of a biodegradable PHA coating, the paper cup retains good recyclability. PHA has a similar degradation rate to paper-based packaging, making it easy to achieve overall degradation in composting or recycling systems, which aligns with Zhejiang Jieyu's commitment to "sustainable and environmentally friendly" packaging.