Sponges can be divided into high-rebound sponges and slow-rebound sponges. Both types of sponges have high density and low density. Of course, the degree of softness and hardness is different.

The high-resilience sponge is produced and processed by polyurethane (PU)-high, medium and low density high-resilience foam composite material. Its main component is polyurethane. It has a large opening rate, and when it is under pressure, it will produce different supporting forces and rebound forces under different deformation states, so it is called a high-resilience sponge.

1. Commonly used sponges are divided into three types: high-density sponge, medium-density sponge and low-density sponge according to their structure. 2. Commonly used sponges are divided into 30-55 degrees according to the hardness (from soft to hard), and the thickness is generally between 0.3-2.3mm. Although the sponges produced by different manufacturers sometimes have the same degree, but the elasticity is still different. Pay attention when purchasing.

3. Commonly used sponges are divided into reverse rubber sponges (with reverse rubber) and positive rubber sponges (with positive rubber)

Density is an important indicator of matter. The high density of sponge means that the voids inside are small and the quality is greater. According to the interpretation of the customs department, the density >=45 is high density, the medium density is <45>18, and the low density is <18.

Sponges are divided into high-density sponges, medium-density sponges, and low-density sponges.

The high-resilience sponge process adopts the cold-molding process to form the high-resilience cold-cured polyurethane foam, which has excellent mechanical properties (high resilience, low hysteresis loss); high compression load ratio, so it has a significant sitting comfort. type; feel similar to latex surface; good air permeability and flame retardant properties.

At the same time, due to the short production cycle, high efficiency and low energy consumption, it has replaced the traditional heat-cured polyurethane foam. At present, there are many large-scale professional PU manufacturers in China.

Common sponges on the market are also divided into two categories: imported and domestic. In the past, it can be easily distinguished from the appearance and feel. The imported sponge has good elasticity, uniform thickness, light weight and slightly soft feel.

The arc ball has strong rotation and the line is standardized. Domestic sponges are heavier in weight, slightly different in elasticity, and feel slightly harder. The arc ball floats and sinks (as the saying goes). Professional players in my country generally use domestic sponges for the forehand, and imported sponges for the backhand. However, the appearance and performance of many joint venture brand sponges are close to imported products, so it is generally difficult to distinguish them.

High-density sponges are sponges with a weight of more than 45 kilograms per cubic meter of sponge.