requirements of silicone for making cups
Food safety requirements
Food grade standards: The silicone used in silicone cups must meet food grade standards. This means that during the production process, the raw materials must be of high purity and must not contain harmful substances, such as heavy metals (lead, mercury, cadmium, etc.) and toxic chemicals (such as polycyclic aromatic hydrocarbons, etc.). For example, in the European Union, food-grade silicone needs to comply with the requirements of (EU) No 10/2011 regulations, and its heavy metal migration has strict restrictions, and the migration limit of lead is 0.05mg/kg to ensure the safety of users during drinking.
No odor: Silicone should have no odor, because odor may affect the taste of water and may be a signal of the volatilization of harmful chemicals. After opening the package, a high-quality silicone cup should only have a faint smell of the silicone itself, which will disappear quickly after cleaning.
Chemical stability: Silicone should have good chemical stability. When it comes into contact with various common beverages, such as water, juice, coffee, tea, etc., it cannot undergo chemical reactions and will not release substances that are harmful to the human body. It needs to be able to withstand a certain range of pH values, for example, drinks with a pH value between 2 and 10 will not cause damage to the silicone cup.
Physical performance requirements
Flexibility and elasticity: Silicone should have good flexibility and elasticity, which makes the cup not easy to break when squeezed or collided. For example, when the cup accidentally falls to the ground, the elasticity of silicone can help it absorb the impact and reduce the possibility of damage. Generally speaking, the Shore hardness of silicone is between 30 and 70A, which ensures that the cup has a certain shape stability and sufficient flexibility.
Strength and durability: Silicone needs to have enough strength to withstand the pressure of daily use. During repeated filling, pouring and carrying, the silicone cup should not be torn or damaged. For some cups with handles, hooks and other structures, the silicone should be able to withstand the corresponding tension in these parts. For example, the silicone in the handle of the cup should be able to withstand at least 5kg of tension without breaking after testing.
Transparency and appearance quality (if it is transparent silicone): If the cup is made of transparent silicone, the transparency of the silicone should be high, and there should be no obvious turbidity, bubbles, etc. that affect the appearance. Silicone with high transparency allows users to clearly see the liquid in the cup, and also improves the overall quality of the cup. Generally, the light transmittance of transparent silicone is required to be above 85%.
Thermal performance requirements
Heat resistance: Silicone cups may be used to hold hot water, so silicone needs to have good heat resistance. It should be able to withstand higher temperatures, for example, at least 100°C without deformation, softening, etc. Some silicone cups may also be used in high-temperature disinfection processes, so silicone that can withstand 120°C or even higher temperatures is more advantageous.
Heat insulation (if required): If the cup design needs to have heat insulation function, the heat insulation performance of silicone itself is also a consideration. Although silicone is not the best heat insulation material, it can be improved through reasonable design, such as a double-layer silicone structure with an air layer formed in the middle. Or combined with other heat insulation materials, the outside of the cup will not be too hot when holding hot water.
Processing performance requirements
Moldability: Silicone should be easy to process and can be made into various shapes of cups through injection molding, extrusion and other processes. For example, during the injection molding process, the fluidity of silicone should be good, and it can evenly fill the mold cavity to ensure that the dimensions of each part of the cup are accurate and the wall thickness is uniform.
Compatibility with other components: If the cup has other components, such as plastic covers, stainless steel filters, etc., silicone should be able to combine well with these components. For example, when silicone and plastic covers are connected by glue or mechanical structure, silicone cannot react chemically with glue, and the firmness of the connection must be ensured.