The important role of EVA foam in packaging materials.

Composition and Structure: Sponge is mainly composed of polyurethane, with the same material as foam. Different manufacturing processes create different types of sponges, classified into polyester sponge and polyether sponge. Polyester sponge is high-pressure sealed foam, while polyether sponge is box-shaped foam.

Polyester Sponge Characteristics: Polyester sponge has strong tensile strength, uniform porosity, high density, and is commonly used in electronics, automotive, printer consumables, precision instrument packaging, and electrical applications. Produced by companies like Inoac Corporation in Japan and Bridgestone Sponge Co., Ltd.

Polyether Sponge Characteristics: Polyether sponge has low density, insufficient strength, and the pore appearance is not as good as polyester. It is commonly produced in China and used in packaging, home, electronics, appliances, toys, luggage, shoe materials, clothing, and other applications.

Hardness: Sponges come in thin, medium, and thick varieties, with variations in softness and hardness. The hardness ranges are: 1. Thin (below 1.0mm-1.2mm), suitable for defensive play; 2. Medium (1.2mm-1.7mm), suitable for a balanced offensive and defensive play; 3. Thick (less than 1.7mm-2.0mm), suitable for an aggressive play. Sponge hardness ranges from 20-35° for soft sponge, 26-40° for neutral sponge, 41-45° for 46-55° for all-round attack (hard sponge), and 56° for approximately super hard.

Production Process:
A. Mix foaming resin, foaming agent, and adhesive resin to give the finished product viscosity.
B. Conduct foaming processing by combining 80 parts of ethylene vinyl acetate (EVA), 20 parts of APAOPT3385, 20 parts of azo dimethylnitrile, 19 parts of CaCO, and 0.6 parts of benzoyl peroxide. Foam the mixture in a mold, and mechanical use produces foamed sponge by breaking the closed cells. Its density (d) is 0.028g/cm, and the compression hardness at 25% is 1.9KPa.

Application Areas: PU sponge, with characteristics such as insulation, heat resistance, sound absorption, shock absorption, flame resistance, anti-static properties, and good breathability, is used in various industries, including automotive, battery, cosmetics, lingerie manufacturing, and furniture manufacturing.

Sponge Material Requirements: Sponge materials (including ultra-soft, medium-soft, super hard, high rebound sponge) must have a smooth and even surface, uniform pore size, no stains, and the same softness as the mold. The cut must be straight and uniform, without waves.

Material Composition: The internal structure of sponge material should not be mixed with other recycled cotton. Each batch of sponge material suppliers must provide product quality certification, including material composition and names, which must comply with environmental standards, maintain the required elasticity, and the density must also meet the corresponding standards.

Size and Quantity: The thickness, width, and length of the sponge must meet the requirements of the company's purchase contract. Length and width are allowed tolerances of ±10mm, and thickness is allowed a tolerance of ±1mm. The quantity, specifications, and models must comply with the order requirements.