Rigidity and Elasticity of Silica Gel Board

The quality of silica gel board is the most important condition that guarantees even heat-seal pressure, so silica gel board must have certain rigidity and elasticity. After long time operation, if silica gel board appears damage or the rubber losses elasticity because of aging, it is unable to guarantee even heat-seal pressure, moreover the scar of the silica gel board surface will cause air bubble in the heat-seal, seriously affecting the heat-seal intensity. Therfore, when selects silica gel board,must pay attention to the rigidity and elasticity of the silica gel board. The required rigidity of silica gel board is generally: when heat-seal aluminum foil bags, the rigidity is HS70; when heat-seal common material, the rigidity is HS50—HS60.

The even rigidity of silica gel board is extremely important to making bags, especially when making bags for frozen food and cooking food, everyday the silica gel board will be pressed continuously 100,000 times to 300,000 times by heat-seal knief which is at 150℃ above high temperature. If the elasticity of silica gel board is not good, or the deviation of the rigidity is above 10℃, will seriously affect the heat-seal intensity. In every 100 bags ,there may be several bags which occasionally occur leak phenomenon, but it is extremely difficult for the quality inspecting personnel to detect, it will cause serious quality accident. We adopt food grade silica gel fo rnipple produced by Toshiba, in which silicon dioxide is Fumed Silica ,made in America. The price of silicon dioxide is 90,000Yuan/1 ton, therefore the deviation of the rigidity is within 5℃ in the continuous bag-making. Because we adopt die-casting method, the superficial flat degree is within 0.05mm.

Other domestically produced silica gel boards are the industrial grade silica gel, which does not conform to food security. Its silicon dioxide uses the precipitation method, the granule is big. Each ton is only about 10,000 Yuan. Therefore its even rigidity cannot guarantee within 10℃, moreover they adopt pushing and extending method, therefore the error of superficial flat degree is above 0.2mm. Durability is not good, the elasticity is extremely easy to aging, it is easy to cause bubble at the heatseal place. The useful life of the silica gel board produced by our company is 2 to3 times than it produced by other companies.