Q My company manufactures a standard range of bulk containers for
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road vehicles. We understand that a container can be insulated by pumping a plastics foam material into the cavity between the walls of a double-skinned container. Is this possible and if so could you give the name and address of a company providing such an insulating service?
A Bibby and Sons Ltd., King Edward
Street, Liverpool 3, produces a type of polyurethane that can be injected in liquid form (Bibbithane) into the cavity to produce a foam. In another form (Bibbicote) it can be sprayed on to a surface.
This company provide a nationwide insulating service for which approved contractors are employed, who will arrange to visit a customer's works with the necessary equipment to insulate a vehicle. Personnel engaged in the service are trained by Bibby.
For the application of Bibbithane, light jigging of the structure is required. Insulating a typical 20ft container takes about a day.
It is notable, incidentally, that polyurethane rigid foams have a high strength-to-weight ratio and low water permeability in addition to low thermal conductivity. In its latest form, the foam has a low volatility which reduces toxic hazards when the material is being applied, and the fact that the two components of the foam are mixed in a ratio of 1 to 1 simplifies its application.
Characteristics of the foam can be varied to cater for specific density and strength requirements to suit the operator. The low viscosity of the foam enables it to be used at low temperatures.
Mixing of the two basic components can be performed with the aid of a special machine, or in a bucket by hand, and results in spontaneous polymerization and progressive solidification. At the same time a blowing agent vaporizes with the rise in temperature and forms a large number of small, closed cells of regular shape. The foam expands during the process and expansion is completed in a few minutes.
Bibbithane is available in densities from 1.8/30Ihicu.ft, the closed-cell content being well over 90 per cent in each case. Bibbicote has a density of 2/31b/cu.ft. and is applicable to a wide variety of surfaces, including metals and timbers. No bonding agent is required.