Everyone is familiar with sponges. Many of the sponges for dishwashing, sofa cushions, seat backs, mattress pillows, toy fillers, and puff makeup eggs in our daily life are made of sponge. If you have seen SpongeBob SquarePants, you must know that sponge is a porous elastic material. Simple but powerful sponges can actually be divided into many types, such as memory foam, PU foam, rubber foam, etc. that are often heard, but they are used as mattress fillers. Which sponge would be more suitable? Today, I will take you to a thorough understanding of [the sponge in the mattress].
1. Raw materials of sponge mattress
The chemical name of the sponge is polyurethane foam, and our commonly used sponges are made of wood cellulose fibers or foamed plastic polymers. The main raw materials for making mattresses are polyether and TDI/MDI (25%-35%), plus some foaming agents and catalysts.
2. Foaming principle of sponge
Sponge has a porous honeycomb structure, and has good softness and water absorption, and is widely used in sofas, mattresses, clothing, flexible packaging and other industries. In order to increase the flexibility and elasticity of the sponge, it is often foamed. There are four main processes for foaming:
a. Prepolymer foaming method
Polyether polyol and diisocyanate are first made into prepolymer, and then water, catalyst, surfactant, and other additives are added to the prepolymer, mixed under high-speed stirring for foaming, and then cured at a certain temperature after curing. .
b. Semi-prepolymer foaming method
Part of the polyether polyol (white material) and diisocyanate (black material) are made into prepolymer first, and then another part of the white material and black material, catalyst, water, surfactant and other additives are added at high speed. Mix with stirring for foaming. This foaming method has certain similarities with the prepolymer foaming method.
c. One-step foaming method
The raw materials such as polyether or polyester polyol and polyisocyanate, water, catalyst, surfactant, foaming agent, and other additives are added in one step, and foaming is carried out after mixing under high-speed stirring. The one-step foaming process is currently a commonly used process.
d. Manual foaming method
This is an easy way to accurately weigh all the ingredients, place them in a container, and immediately mix them well and inject them into a mold or space that needs to be filled with foam. The polyisocyanate is weighed in last.
The above are the four commonly used foaming methods. After foaming treatment, the sponge can obtain better elasticity and water absorption, which can meet the needs of many industries for sponges.
3. Classification of sponges
a. Chemical classification
From the point of chemical subjects, sponges can be divided into: ordinary sponges, slow-rebound sponges, and high-resilience sponges.
b. Process classification
According to the production process of the sponge, the sponge can be divided into: cutting type and molding type.
The cutting category is further divided into ordinary sponge, slow rebound sponge (memory foam: warm/non-warm), high rebound sponge, and imitation latex sponge.
The molding category is divided into air-sensing sponge, warm-sensing sponge, ordinary slow rebound, ordinary high rebound, and imitation latex sponge. Conventional pillows and mattresses generally use three types of sponges: [air, temperature, and ordinary slow rebound]. General cushions use ordinary high-rebound sponges as raw materials, such as lavender and coconut. My pillows often use imitation latex sponges. make.
The difference between cutting and molding: There are differences in the process and raw materials. The cutting sponge is a sponge foamed by an assembly line, and the molding sponge is a product molded by a mold. The molding process of some special-shaped products will be simpler, and it will reduce the waste of raw materials. .
To sum up, from the classification point of view, it can be concluded that: sponge > memory foam > non-warm memory foam, that is to say, non-warm memory foam belongs to memory foam, and memory foam belongs to sponge. In the market, ordinary foam and memory foam are generally used as the filling layer of the mattress.
4, sponge density and hardness
a. The density of sponge is generally represented by D
D=kg/m³. Take a chestnut: 25D means that each cubic sponge weighs 25kg.
Ordinary sponge: 18D-40D
Air sponge: 28D-55D
Imitation latex sponge: 50D-55D
Slow rebound sponge: 33D-80D
The higher the density, the harder the sponge: In general, the hardness and softness of the sponge have no great relationship with the density. The softness and hardness are mainly changed by adjusting the formula. The same density of sponges can be made with different hardnesses.
b. The hardness of sponge is expressed by ILD
The higher the ILD, the harder the sponge. Take a chestnut: 20 pounds of ILD sponge means that the material requires 20 pounds of pressure to compress the sponge by 25%.
Soft sponge: 20-35ILD
Neutral sponge: 36-40ILD
Hard sponge: 41-45ILD
Hard sponge (full attack type): 46-55ILD
Super hard type ≈ 56ILD
The normal range of slow rebound ILD is 9-15, and the range of ordinary cotton ILD is 32-45.
When the sponge is used in the mattress, its softness and hardness can be adjusted through different ratios, and mattresses with suitable hardness and softness can be made for different groups of people.
