Soft PU foam technology

Intermittent box method
It is simpler and suitable for small-scale factory production. It mixes all the components in the formula at high speed and pours them into a box to foam them into pieces.

Continuous block method
It is divided into three types: dome foaming method (ie, traditional foaming method), horizontal flat-top foaming method and vertical foaming method.
1. The foam utilization rate of the dome foaming method is only about 85%, and there are many corner scraps.
2, horizontal flat-top foaming method: foam utilization increased to 90-92%, of which foaming technology is divided into: overflow trough, turbulent plate type, low pressure top type and high pressure top type.
3, vertical foaming method: the foam utilization rate is further increased to 95-98%, the corner scrap is less, and the equipment footprint is small, the isocyanate diffusion is less, the color choice, shape and variety are easy to change.

Molding
The main products are mats, mostly applied in the user site, reducing transportation costs.

Example 1: The box method foaming formula is
Polyether (molecular weight 3000) 100
Toluene diisocyanate (80/20) 47
Triethylenediamine 0.2
Stannous octoate 0.3
Silicone oil 2.3
Distilled water 3.5
The process conditions are: 20-25 ° C, and the stirring time is 8 seconds.

Example 2: Polyisocyanurate foam
Ordinary PU foams have poor heat resistance and can only be used below 100 °C. The polyisocyanurate foam (PIR) has a long-term use temperature of 150-180 ° C, and the flame retardancy is better than PU.
Modified isocyanurate varieties include: urethane, epoxy resin, polyimide, carbodiimide and the like.
PIR Formulation I Formulation II
Crude MDI: 80.5 polyisocyanate 100
Hydroxyl-containing compound 6.1 Phosphorus-containing polyether 10
Propylene oxide 1.43 (including trimerization catalyst)
Silicone oil surfactant 0.86 3003 polyether 20
Blowing agent F-II 10.0 Alkyl phosphorus compound 0.5
Trisphenol 0.58 Surfactant 0.5
Azacyclopropene 0.58
The emulsification time is 18 seconds.
Curing time 45 seconds
Example 3: Molded high resilience soft polyurethane foam
The high-rebound soft foam, called HR foam, is a high-performance cushion material that can be cold-cured and reduced from the 23 minutes used in a production cycle to 13 minutes.

There are currently three technical synthetic routes for the production of HR foam:
1. Graft polymerization of a vinyl monomer and a polyol: a polymer polyol, and the product is a dispersion.
2. From the polyamine polyol, a stepwise polyaddition reaction occurs to form a branched copolyol, that is, a polyurea polyol route.
3. Modified MDI synthetic HR route: cold curing HR foam with all diphenylmethane diisocyanate (MDI). The advantages of this method are: short production cycle, fast demoulding and low toxicity.
Formulation 1: high activity polyether 60, polyurea polyol 40, crosslinker 1, catalyst 0.6, water foaming agent 2.5, stabilizer 1.0
Formulation 2: high activity polyether 60, polymer polyol 40, crosslinked Liu 2.5, catalyst 0.6, water foaming agent 2.7, stabilizer 0.02
Formulation 3: high activity polyether 100, crosslinker 2.5, catalyst 0., 8, water foaming agent 3.5
Formulation 4: high activity polyether 65, polyurea polyol 35, crosslinker 3.0, amine catalyst 0.5, organotin catalyst 0.02, water foaming agent 2.5, stealing agent 0.75