Kitty Jiao

Out Shell

When I consider the design of the product’s shape, I should also consider whether the application of the material is reasonable, and whether there is a corresponding technology to complete the design I want.

Therefore, refering to the material application of the children's safety chairs and some materials used in the pet equipments,  I tried to understand the following types deeply.

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1. PUR

Polyurethane is a polymer having urethane chain repeat structural units prepared by reacting isocyanates with polyols. PUR products are divided into two categories: foamed products and non-foamed products. Foamed products include soft, hard, semi-rigid PUR foams; non-foamed products include paints, adhesives, synthetic leathers, elastomers, and Elastic fibers. PUR material has excellent performance, wide range of applications, and many types of products, among which PUR foam is the most widely used.

Soft PuR foams and semi-rigid PUR foams are mainly used for furniture liners and decorative materials, automotive mats, carpet underlays, garment linings, construction sound-absorbing materials, sports mats, mattresses and instrument packaging materials, etc. aspect. Among them, the main uses of molded soft PUR foams are automobile seat mats, motorcycles, bike seats, and the like.

Due to the excellent plasticity of PUR and the strong practicality of materials, its application in automobiles is expanding.

2. EPP

EPP (Expanded polypropylene) is a high-performance polymer/gas composite material with excellent performance. With its unique and superior performance, EPP has become the fastest growing new environmentally-friendly compression cushion thermal insulation material. EPP products have excellent anti-seismic performance, high recovery after deformation, good heat resistance, chemical resistance, oil resistance, and heat insulation. In addition, the products have light weight and can greatly reduce the weight of articles.

Another particularly important application area is the numerous applications in the automotive industry: automotive bumpers, automotive side shock cores, automotive door shock cores, advanced safety car seats, child safety seats, tool boxes, trunks, armrests, and bottoms Pads, sun visors, dashboards, etc.

3. EPS

Expanded Polystyrene (EPS) is a lightweight polymer. It is the use of polystyrene resin to add foaming agent, while heating to soften, produce gas, forming a rigid closed-cell foam structure.

The closed cavity structure of EPS determines that it has a good thermal insulation, and its greatest feature for thermal insulation materials is its extremely low thermal conductivity. The thermal conductivity of various EPS plate types is 0.024W/mK~0.041W/mK. .

The cavity structure of the EPS makes water infiltration extremely slow. According to the actual measurement data from Norway and Japan, the EPS water absorption rate (the amount of water ingested is equivalent to the percentage of its bulk density) is not less than 1% when it is not immersed in water, 4% or less in the vicinity of groundwater table, and is about 10% when immersed in water for a long time. . Since the bulk density of the EPS is much lower than the bulk density of the soil, the 1% to 10% increase in bulk density caused by water absorption has negligible impact on the project.

EPS is currently the lightest packaging material. EPS is applied on children's safety seats and has the ability to be cracked and absorb impact forces.

At present, many people have a wrong understanding that the thicker the bubble, the better the elasticity, but this is not the case. The better elastic foam means that it has a weaker ability to absorb collision impact, because it will be released to the baby's body after absorbing the impact force, and it will not achieve cushioning and shock resistance.