Insulating material

An insulating material in the form of a body comprising expanded plastics beads which are each encapsulated in bitumen or a bituminous compound which has a softening point more than 10.degree. C. higher than the melting point of the beads and is free from solvents, light oils, emulsifiers or other liquifying agents, such encapsulation having been formed with the bitumen or bituminous compound in liquid form in a hot process, the encapsulated beads having been expanded prior to processing with the bitumen or bituminous compound and, subsequent to this processing, pressed together and distorted to form a body with voids between the heads substantially eliminated.

A method of making an insulating material which comprises heating bitumen or a bituminous compound which is free from solvents, light oils, emulsifiers or other liquifying agents to a temperature appreciably above its softening point in order to make it liquid and free running and processing expanded plastics beads therewith so as to completely encapsulate each of the beads, the bitumen or bituminous compound having a softening point which is more than 10.degree. C. higher than the melting point of the beads.

A method of making an insulating material body which comprises heating bitumen or a bituminous compound which is free from solvents, light oils, emulsifiers or other liquifying agents to a temperature appreciably above its softening point in order to make it liquid and free running, processing expanded plastics beads therewith so as to completely encapsulate each of the beads, and, while the encapsulating bituminous material is in a semi-liquid state, pressing the encapsulated beads together and distorting them so as substantially to eliminate voids between the beads, the bitumen or bituminous compound having a softening point which is more than 10.degree. C. higher than the melting point of the beads.