| 摘要 |
In a method of mixing and dispensing liquid components to form a foamed (especially polyurethane) plastic, they are turbulently mixed by compressed air in a primary mixing chamber and then conveyed through an elongated secondary mixing chamber in which further mixing and reaction take place. In an example a partial pre-polymer having an -NCO to -OH ratio of 7,2:1 was made by heating together for 1 hour at 110 DEG C. 80 parts by weight of an 80:20 mixture of 2,4 and 2,6 tolylene di-isocyanate and 20 parts of a liquid polyester resin having an OH number of 360, an acid number of 1 and a water content of 0,1%. A mixture was also made of 91,8 parts by weight of the same polyester, 2 parts of N-methyl morpholene, 5,4 parts water and 0,8 parts sorbitan monopalmitate. 100 parts of the partial pre-polymer and 60 parts of the polyester/N-methyl morpholene mixture were supplied to the apparatus described (see Group II) at an aggregate rate of flow of 5 lb. per minute by air at 50 p.s.i. and the mixed material was discharged into a mould as a milky material in the pre-foaming stage. The air pressure is limited to a range 10-70 p.s.i., which is less than that required to atomize the components.ALSO:In a method of mixing and dispensing liquid components to form a foamed (especially polyurethane) plastic, they are turbulently mixed by compressed air in a primary mixing chamber and then conveyed through an elongated secondary mixing chamber in which further mixing and reaction take place. In an example a partial pre-polymer having an -NCO to -OH ratio of 7,2 : 1 was made by heating together for 1 hour at 110 DEG C. 80 parts by weight of an 80 : 20 mixture of 2, 4 and 2, 6 tolylene di-isocyanate and 20 parts of a liquid polyester resin having an OH number of 360, an acid number of 1 and a water content of 0,1%. A mixture was also made of 91,8 parts by weight of the same polyester, 2 parts of N-methyl morpholene, 5,4 parts water and 0,8 parts sorbitan monopalmitate. 100 parts of the partial prepolymer and 60 parts of the polyester/N-methyl morpholene mixture were supplied to the apparatus described (see Group II) at an aggregate rate of flow of 5 lb. per minute by air at 50 p.s.i. and the mixed material was discharged into a mould as a milky material in the pre-foaming stage. The air pressure is limited to a range 10-70 p.s.i., which is less than that required to atomize the components.
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