Soft foam common problems and solutions

The amount of accidents and problems encountered in the actual foam production is diverse, each incident of production are caused by many factors. In the accident analysis of complex factors, it is generally difficult to list all the factors and the main factors that really works. The following summarizes some of the causes of accidents and frequently encountered. 1, anxious (oxidation reaction temperature exceeds the central temperature of the material) (1) a polyether polyol quality problems: the production process, to the product water storage exceeded, a peroxide, the low boiling impurities content is too high, the metal ion concentration high, equipped with improper antioxidant type and concentration; (2) formulation: low density formulation, TDI index is too high, improper physical blowing agent and blowing agent proportion of water, less than normal amount of physical blowing agent, an excess of water ; (3) climate: high summer temperatures, heat slowly, high melt temperature, air humidity, oxidation reaction temperature exceeds the central temperature; (4) improper storage: TDI index when deposited increases, thermal energy increases after aging large causing the internal temperature rises and anxious. 2, a large compressive deformation (1) a polyether polyol: a functionality of less than 2.5, the ethylene oxide ratio is greater than 8%, a small molecule multi-component, degree of unsaturation greater than 0.05mol / kg; (2) Process conditions: Reaction Center temperature is too low or too high, the curing is not good, not fully or partially anxious reaction; (3) the process recipe: TDI index is too low, excess stannous octoate silicone oil, low foaming ventilation, closed cell rate. 3, the foam is too soft (hardness decreases at the same density) (1) Polyether polyols: low functionality, low hydroxyl value, high molecular weight; (2) the process recipe: a small amount of stannous octoate, gel reaction is slow in the case of the same amount of tin, less water, physical blowing agents, large amounts of silicone oil high activity, lower TDI index. 4, coarse cells (1) mixing well; uneven mixing, short Cream; (2) Formulation process: the amount of silicone oil is below the lower limit, stannous octoate and with less difference in activity, slow gelation. 5, higher than the set density (1) Polyether polyols: low activity, high molecular weight; (2) Formulation process: the amount of silicone oil is less than the lower limit value, low TDI index, low foaming index; (3) Climate conditions: low temperatures, High air pressure. 6, bubble collapse holes (gas evolution rate faster than the gel) (1) Polyether polyols: acid seriously overweight, impurities, low activity, relatively high molecular weight; (2) the process recipe: an amine with less than the amount of tin low index TDI, TDI index is too high when the same amount of tin, hair gel faster than the speed of the air, the strength of the skeleton and small bubbles or a partial collapse of holes. 1, a high closed cell (1) a polyether polyol: a high proportion of ethylene oxide, highly active, occurs in the active switch to a different polyether polyols; (2) the process recipe: more than the amount of stannous octoate, the isocyanate-reactive high, a large degree of crosslinking, high crosslinking speed, excess amine and a physical blowing agent within the foam caused by depression, open cell foam is not elastic, closed cell will lead to high .2 TDI index is too large, shrinkage (foaming gel faster than the speed) (1) closed cell high shrinkage upon cooling; (2) process conditions: low temperature and low material temperature; (3) the process recipe: silicone excessive, excessive physical blowing agent, TDI .3 index is too low, the crack (1) process conditions: low temperature, high temperature reaction center; (2) the process recipe: low index TDI, tin, high early strength foam; (3) high activity silicone oil, the amount of .4 less, capping (issued airgel velocity imbalance) (1) process conditions: low temperature and low material temperature; (2) the process recipe: less than the amount of catalyst, with less amine, a silicone oil .5 poor quality, corner cracking (excessive amount of amine, foaming speed too fast) surface macropore: excessive physical blowing agent, silicone oil, and the difference between .6 catalyst mass, low temperature performance difference foam inherent quality difference polyether polyol, hydroxyl value in the same , low functionality, unsaturation degree, when the same amount of tin, TDI index .7 low, poor ventilation (1) weather conditions: low temperature (2) Materials: high polyether polyol, a high activity silicone oil; (3) process formulation: tin, tin or less the same amount of water and the amine content, TDI index .8 high rebound and poor (1) raw materials: a polyether polyol of high activity, low molecular weightHigh activity silicone oil; (2) the process recipe: silicone large, amount of tin, the tin more water at the same dosage, TDI a high index, poor tensile strength (1) Materials: too much low-molecular polyether polyols, with a low hydroxyl value functionality; (2) the process recipe: tin less good gel reaction, when the same amount of tin, TDI high index, low cross-linking degree of less water .2, smoke excess amine and water causes foaming TDI reaction to release a large amount of heat, smoke and evaporation of low boiling materials. if not anxious, then the majority of the TDI fumes, low-boiling substances and the polyether polyol monomer cycloalkanes .3, foaming and foam with white bars gel reaction speed, transmission speed is slow in continuous foaming, the local pressing generates a dense layer, generation of white bars phenomenon should be promptly improve the transmission speed, or reducing the material temperature, reducing the amount of catalyst .4, crisp foam formulation in water more biuret dissolved in the silicone oil is not more than a tin catalyst difference, the crosslinking reaction is insufficient, small molecular weight polyether polyol high content, the reaction temperature is too high, cleavage of ether bonds reduces the strength of the foam .5, foam density is less than the set value due to inaccurate measurement of the foam index is too large, the high temperature, low pressure .6, foam skin having a bottom, side skin, at least the bottom step empty tin polyamines, slow foam, gel speed, the continuous belt foaming temperature is too low .7, large elongation (1) raw materials: a polyether polyol of high activity, low functionality; (2) the process recipe: low crosslinking index is less than the TDI, tin , silicone oils more; (3) high temperature