<P> Solo Cup Company is an American manufacturer of disposable consumer products including beverage cups, disposable plates and bowls . Solo Cup Company is located in Lake Forest, Illinois, and in 2006 had sales of $2.4 billion . On May 4, 2012, Solo Cup Company was acquired by Dart Container . </P> <P> Leo Hulseman, a former employee of the Dixie Co. in the 1930s, created the "Solo Cup", a paper cone he made at his home and sold to bottled - water companies . He founded the Solo Cup Company in 1936, and developed other products, like wax - coated cups and the plastic Cozy Cup . The wax - coated cups were added to its lineup in the 1950s, as fountain sodas gained popularity . </P> <P> In the 1970s, Hulseman's son, Robert Leo Hulseman, came up with the now - ubiquitous red Solo cup . The red Solo cups are made of thick, molded polystyrene . They are known for being able to withstand drops, easily stackable, and disposable while price accessible . Their characteristic red color may conceal the drinking contents . </P> <P> On March 1, 2004, Solo acquired Sweetheart Cup Company for $917.2 million, in part with public debt . Sweetheart was founded by Joseph Shapiro and his four brothers, emigrants from Russia . It became the largest consumer packaging company in the world and was sold several times before being acquired by Solo Cup . Following the acquisition, Solo Cup's finances suffered, and Standard & Poor's lowered their credit rating from B to CCC+ . In late 2006, Solo Cup was reported to be $1.1 billion in debt . </P>

When were red solo cups introduced to the market