COMPLIANCE INFO_PRE 2019 - Laserfiche WebLink

Home Browse Search

i /¢ l• R values increase, it can mean incorrect proportions of the chemical ingredients has taken place. An increase in normal compression set values does require im- mediate action to determine the cause. Another accelerated test for urethane foam is humidity aging. Resistance to humidity or more precisely, the change in the physical properties of the foam after this accelerated aging is the last of the physical properties we will examine. Various conditions for this accelerated test have been established, the most common and most severe is a 5 hour period at 250 degrees F. or approximately 15 lbs. saturated steam pressure. It is possible for any physical test we have discussed to be repeated after the accelerated aging and the change in measurement evaluated. Low density foams with their larger percentage of urea cross links and large exotherm do give excellent results in the two areas most closely examined, namely compression set and 25% ILD. Both values will remain fairly constant. Their resistance to this test should not be interpreted as giving "trouble-free" use in service. Conditions of high humidity and high temperatures will attack the urethane linkage to a somewhat greater degree. High density foams with their greater concentration of these urethane linkages may have a greater change in properties after humidity aging. This greater change should not give concern to the user. What must be examined are the severity of the conditions of test and their relationship to service life. High density polyether urethane foams have been in service for approximately ten years and no indication of failure because of humid conditions is evident. As with the other properties there is a normal value for each formu- lation and the continuous monitoring will indicate a production varia- tion when it occurs. We have examined the chemistry and properties of the present foams available. What new products does the urethane industry have to offer? The tire and rubber industry have for years used carbon blacks to reinforce their products. The urethane foam industry is turning to this same concept of reinforcement to increase foam firmness. Union Carbide has recently introduced a new polyol. Incorporated into the polyol chain are different chemical groups. The first polyol they have offered contains vinyl groups. These groups physically reinforce the urethane chains to produce firmness. In addition to these organic materials, finely divided inorganic materials will also contribute a reinforcing action. Most of the rein- forced or heavy density foams on the market today use this technique. 11