Harold E. Reymore

Isocyanu rate Foams: Chemistry, Properties and Processing

The literature has become replete with references to the physical and mechanical properties of laboratory prepared isocyanurate foams and methods of modifying these products. Little attention has been given to the chemistry and mechanism of isocyanurate formation, or to methods of adopting this reaction to produce foams on a commercial scale. Accordingly, the purpose of this paper is to review the chemistry of isocyanurates and the mechanism for their formation. Also presented are general chemical formulations, physical properties and processing conditions for continuous lamination, bun, pour and spray applications. Typical physical properties of these low density isocyanurate foams, including laboratory flammability characteristics,

Novel Isocyanurate Foams Containing No Flame Retardant Additives

these chemicals [4, 5] . The toxicity of the gases generated during the combustion of cellular polymer containing these flame retaidant additives in a real fire situation, however, are now known [6-8]. It is reasonable to assume that cellular plastics insulation used in building construction which do not contain halogen or phosphorus additives should generate less noxious gases during combustion. Accordingly, the purpose of this paper is to describe a significant technical advancement toward the development of improved isocyanurate foam insulation. These urethane modified isocyanurate foams contain no added flame suppressing agents. The absence of flame retardants permits the preparation of isocyanurate foams with improved thermal stabilities, lower smoke values and friabilities while still meeting model building code requirements of less than 751 flame spreads and less than 4501 smoke densities when tested in accordance with the ASTM E-84 Steiner tunnel.

Thermal Degradative Behavior of Selected Urethane Foams Related to Variations of Constituents Part II. Chemical Reactions in Urethane Decomposition

arylisocyanates), carbon dioxide and olefin, the olefin having arisen from the polyol part, and (3) a different cleavage involving loss of CO2 and coupling of the polyol residue with the aromatic amine to form secondary amines. These most important reactions are indicated in Figures 12 and 13. Later reactions may occur involving all these fragments, especially those not distilling off and perhaps certain oxidations in the presence of air. In summary, there can be (1) fragmentation, (2) interaction of fragments. (3) air oxida-

Thermal Degradative Behavior of Selected Urethane Foams Related to Variations of Constituents: Part I. Thermal Stability and Test Methods

Relating the thermal stability of a rigid urethane foam to its chemical composition and structure is made difficult by two basic characteristics. These are the overall composition of the urethane foam and the perhaps vague term, thermal stability. A typical urethane foam formulation includes at least six components: isocyanate and polyol comprising the bulk, with lesser amounts of fire retardants, fillers, catalysts, and blowing agent. Thermal stability is a rather vague term. Each problem encountered in studying heat stability might itself be considered as a working definition of such stability and could establish criteria. Among these are: weight and strength loss versus time and

A New Generation of Structural Foam Polymers

pioblem of designing a functional or decorative part he has many choices of materials before him. Should the part be fabricated from metal by conventional pressing and assembly techniques or should the part under consideration be made from plastic? If a plastic part is feasible or indicated, the engineci is now faced with the difficult choice of which polymer and which process should be used to arrive at the most satisfactory part, with regard to function, at the lowest possible cost. The engineer will consider the dimensions and complexity of the part, together with the stress and temperature environment to which it will be exposed in finishing and in service. This knowledge will suggest possible polymers and processes, however, before any final decisions can be made consideration must inevitably be given to such factors as the volume of production required, the tooling cost, capital investment related to possible

Computer Simulation of Isocyanate Based Structural Foam Molding

Table 1. Formulation of Dermathane ID-386-12. over designed and sometimes parts were underdesigned. Material suppliers have recognized this problem but to date very little of this needed information has been published. To appreciate why, let us define the problem. What are the physical properties of non-cellular structural materials such as, ABS, epoxy, steel? They are numbers, absolute values. Flexural strength, flexural modulus, tensile strength etc.,

Polyurethane Chair Shells

but is reprinted here as a service to our subscribers. shapes. However, it is more expensive to fabricate and difficult to attach padding and fabrics. Rigid low density polyurethane foam is the first serious competition for the hardwood skeletons. It competes with extreme design versatility and it competes economically. To substantiate this, consider the process. Two reactive liquids are mechanically mixed and poured into a chair shell mold

Unisystem—A New Concept in Urethane Foam Moldings

The literature has become replete with references to various polyurethane foam formulations and their applications. Each reference generally describes a limited number of formulations directed to specific applications. Anyone involved in a molding operation, and in particular molding parts for the automotive industry, fully realizes that specific requirements and formulations are needed for each part being molded. If a large number of parts are being manufactured, with diverse property requirements, than an inventory of a variety of chemicals are required to produce these parts. This can become an expensive proposition in terms of inventory and quality control requirements, and needless to say, that purchasing of fewer chemicals in large volume could be made more economically. This article describes the UNISYSTEM approach to urethane foam technology wherein semiflexible, integral skin flexible, microcellular and integral skin rigid foams, suitable for a variety of applications, can be prepared from a basic set of