Molded foam articles prepared with reduced mold residence time and improved quality

A reaction system suitable for the production of expanded moldings by the RIM process comprising:

• a polyisocyanate composition including a polyisocyanate having a number averaged isocyanate group functionality of at least 1.8;
• an isocyanate reactive organic composition including at least one organic polyol having a number averaged functionality of primary and/or secondary alcohol groups of at least 1.8;
• at least one blowing agent;
• at least one fatty polyester compound of 20 carbon atoms or greater, the fatty polyester containing at least 4 ester groups per molecule;
• and
• a polysiloxane composition including an effective amount of at least one polydimethylsiloxane polyoxyalkylene copolymer containing from greater than 70 to less than 150 siloxane linkages;
• wherein the polydimethylsiloxane polyoxyalkylene copolymer containing greater than 70 to less than 150 siloxane linkages conforms to the following formula I:
• R3Si—[O—SiR′R″]n[O—SiR′″R″″]m-O SiR′″″3 (I)
• wherein R, R′, R″, and R′″″ may be the same or different and at least 90 mole percent of the groups R, R′, R″, and R′″″ are CH3 groups;
• all of the groups R, R′, R″, and R′″″ are hydrocarbon groups of 4 carbons or fewer;
• the number averaged value of n is at least 60;
• the number averaged value of m is from 2 to 8;
• the groups R′″ and R″″ may be the same or different and are selected from the group consisting of aliphatic hydrocarbons of 4 carbons or fewer and polyoxyalkylene blocks according to formnula II;
• and at least one of the groups selected from R′″ and R″″ is a polyoxyalkylene block according to formula II:
• -L-O—[PO]x[EO]y-O-T (II)
• wherein PO denotes an oxypropylene unit and EO denotes an oxyethylene unit;
• the number averaged value of x is from 15 to 30;
• the number averaged value of y is from 8 to 40;
• the ratio of x/y is from 1.1 to 3;
• the group L is an optional divalent linking group which, when present, is a divalent aliphatic hydrocarbon group having fewer than 10 carbon atoms;
• and the group T is selected from the group consisting of hydrocarbon groups of less than 10 carbon atoms.

A reaction system suitable for the production of expanded moldings by the RIM process comprising:

• a polyisocyanate composition, including a polyisocyanate having a number averaged isocyanate group functionality of at least 1.8;
• an isocyanate reactive organic composition including at least one organic polyol having a number averaged functionality of primary and/or secondary alcohol groups of at least 1.8;
• at least one blowing agent;
• at least one fatty polyester compound of 20 carbon atoms or greater, the fatty polyester containing at least 4 ester groups per molecule;
• and
• an effective amount of at least one polydimethylsiloxane polyoxyalkylene copolymer containing from greater than 70 siloxane linkages, to 100 siloxane linkages;
• wherein the at least one fatty polyester compound is free of aromatic rings;
• wherein the polydimethylsiloxane polyoxyalkylene copolymer is further characterized by containing from 35 to 70% of its molecular weight in the form of dimethylsiloxane units, by having a molecular weight in the range of 10000 to 18000, by containing a plurality of aliphatic ether linkages, and by containing less than 10 mole percent of oxyalkylene units other than oxyethylene or oxypropylene units;
• and
• wherein the polydimethylsiloxane polyoxyalkylene copolymer containing from greater than 70 to 100 siloxane linkages conforms to the following formula I:
• R3Si—[O—SiR′R″]n[O—SiR′″R′″″]m-O SiR′″″3 (I)
• wherein R, R′, R″, and R′″″ may be the same or different and at least 90 mole percent of the groups R, R′, R″, and R′″″ are CH3 groups;
• all of the groups R, R′, R″, and R′″″ are hydrocarbon groups of 4 carbons or fewer;
• the number averaged value of n is at least 65;
• the number averaged value of m is from 3 to 6;
• the groups R′″ and R″″ are individually selected from the group consisting of CH3 groups and polyoxyalkylene blocks according to formula II;
• and one of the groups selected from R′″ and R″″ is a polyoxyalkylene block according to the following formula II:
• -L-O—[PO]x[EO]y[AO]z-O-T (II)
• wherein PO denotes an oxypropylene unit, EO denotes an oxyethylene unit, and AO denotes an optional oxyalkylene unit of greater than 3 but fewer than 6 carbons;
• the number averaged value of x is from 18 to 25;
• the number averaged value of y is from 12 to 20;
• the ratio of x/y is from 1.2 to 2;
• the group L is a divalent linking group which is a divalent aliphatic hydrocarbon group having fewer than 10 carbon atoms;
• and the group T is selected from the group consisting of hydrocarbon groups of fewer than 5 carbon atoms.