TH
URETHANE POLYMERS IN A MODERN
OFFICE BUILDING
HE erection of a new headquar- ters for the Dyestuffs Division of Imperial Chemical Industries Limit- ed in Manchester gave an ideal op- portunity for testing the developing uses of rigid and flexible urethane surface coatings in modern building construction and fitting out. Eigh- teen months of normal occupation of the offices has given an opportunity to review the performance of the many novel materials and structural techniques used.
Imperial Chemical Industries has been associated with the chemistry and technology of urethane polymers since their discovery in the late 1930s. and has contributed greatly to their rapid commercial development. It was therefore natural that every effort
was made to ensure that polyurethane materials were used wherever possible in the construc- tion of the new building. Now. after the building has been in use for some eighteen months. the company feels that their faith in these ma- terials, then new to the building in- dustry, has been justified.
The building industry today has available a wide range of thermal
insulation materials. the economics of which are well known. The com- parative performance of the available insulating materials has been review- ed (2) and their principal properties are summarised in the accompanying table. The initial decision whether to insulate a building must be made. after comparing the cost of the in- sulation (materials and labour) with the economies resulting from (i) the lower capital cost on boilers for cen- tral heating, (ii) oby us savings in lower running costs of installed heating, (iii) less obvious savings in the reduced heating needed to raise the building temperature after shut- down for holidays and weekends, and (iv) in reduced absenteeism brought about by improved working conditions. It can be shown (1) that the cost of insulation can be recover- ed through the savings listed above in a period of only a few years.
Because of its unique physical properties. rigid urethane foam is an excellent insulating material. A thermal insulant acts by restricting
Figure -Spraying a layer of a Daltolac 41/Suprasec
D composition on to the interior wall.
the movement of gases (which would otherwise give rise to losses by con- vection) and ideally comprises a mass of small gas bubbles emmeshed in a solid of low heat conductivity. In rigid urethane foam 95% of the volume is made up of fine discrete cells which restrict convection losses, and the remaining 5% of the volume is occupied by the load-bearing fibrillar structure of the foam.
Furthermore, if the cells contain a of low high-molecular-weight gas thermal conductivity, such as the
of vapour
trichlorofluoromethane (Arcton 11). the thermal conductivi- ty of the foam is correspondingly re duced. Only rigid urethane foam can be formulated in this manner. The foam is thus a thermally efficient insulant of low K value and high strength/weight ratio. and it also satisfies other criteria of an insulat- ing material as quoted elsewhere (2).
It is sufficiently strong to contri bute to the structural strength of as- sociated materials, and to resist oc- casional damage. It is resistant to moisture. chemicals, vermin. mould,
Figure 4 - Main entrance flanked by urethane foam panels faced with ceramic tiles and backed by plywood.▼
THE HONG KONG & FAR EAST BUILDER-VOLUME 18. NUMBER 2
101