Integrally skinned

The sandwich-type stmcture of polyurethanes with a smooth integral skin produced by the reaction injection molding process provides a high degree of stiffness as weU as exceUent thermal and acoustical properties necessary for its use in housing and load-bearing stmctural components for the automotive, business machine, electrical, furniture, and materials-handling industry. 

Semiflexible molded polyurethane foams are used in other automotive appHcations, such as instmment panels, dashboards, arm rests, head rests, door liners, and vibrational control devices. An important property of semiflexible foam is low resiHency and low elasticity, which results in a slow rate of recovery after deflection. The isocyanate used in the manufacture of semiflexible foams is PMDI, sometimes used in combination with TDI or TDI prepolymers. Both polyester as well as polyether polyols are used in the production of these water-blown foams. Sometimes integral skin molded foams are produced. 

Integral-skin polyurethane products - The current alternatives for these products include HCFC-22, hydrocarbons, carbon dioxide/water, HFC-134a, pentanes, and HCFC-141b. The long-term alternate is expected to be carbon dioxide/water. 

Insertion mechanism, 231 Integral skin foams, 205 Integrated circuit modules, dielectrics for, 270-271... 

Unlike other polymers, we have no universally accepted chemical nomenclature for polyurethanes. Instead, we typically refer to polyurethanes in terms of their general characteristics. Thus we refer to flexible polyurethane foams , polyurethane elastomers , integral skin polyurethane foams , and others. 

Rigid integral skin polyurethane foams are used to make seat pans, office equipment housings, tanning beds, water skis, and surfboards, all of which must be light and stiff. 

The European Parliament has adopted phase-out dates for the use of HCFCs in rigid foam applications which are basically in line with those in the USA and Japan. From 1 January 2000, the use of HCFCs for integral skin PU and PE foams is prohibited. From 1 January 2002, the use of HCFCs in expanded PS foams is prohibited. From 1 January 2003, the use of HCFCs in flexible-faced PU foam laminates, appliances and sandwich panels is prohibited. EUROPEAN PARLIAMENT... 

Kulprathipanja and coworkers reported the preparation of integrally skinned siUcaUte-1/cellulose acetate flat sheet asymmetric mixed-matrix membranes via phase inversion technique in 1992 [73]. The O2/N2 separation performance of these membranes was investigated. It was demonstrated that the separation factor of... 

MOULD EPP BEAD FOAM WITH AN INTEGRAL SKIN... 

The article describes the process of producing expanded polypropylene foam parts with a solid integral skin on one side, citing a bicycle helmet moulded from BASF s Neopolen EPP bead, as an illustration. The self-skinning EPP process reqnires some modification of standard beadmoulding equipment, needing an extra steam chamber. Automotive interior trim is a potential application for the process. 

Isoderm Urethane integral-skinning foam Upjohn... 

The rigid urethane foam concept with integral skins has also found considerable interest in the automotive industry for exterior body parts, such as engine or trunk compartment lids, fenders and even full roofs. These parts can be reinforced with metal inserts where necessary or hinges and fasteners can be molded in for ready mounting. 

Here, the case of free rise in an open mold is analyzed. Because of the very low thermal conductivity of a plastic foam, an adiabatic process will be considered. The nonadiabatic case in a closed mold leads to integral-skin foams. These foams exhibit a mass density gradient, with unfoamed skins in contact with the mold walls (Marciano et al., 1986). 

Integral skinned These integral skin urethanes are designed to have an outer layer that is not foamed, with a foamed inner section. This provides a firm feel without the dirt trapping of the cut cells. Typical examples of this style are steering wheels and motor car fascias. 

The cell density (number of cells per unit cross-section area or volume) is also used to characterize the coarseness or fineness of foam. Foamed products can feature a deliberately created inhomogeneous (nonuniform) morphology. An example is when a foamed core is sandwiched between solid skins as in so-called structural foams, or in elastomeric products with so-called integral skins. With cells elongated in the direction of foam rise or melt flow, the process will give an anisotropic structure and properties (Chapter 15). 

Use is made of integral skin foams. They are flexible urethane foams with a high density skin. They are used in applications such as steering wheels, arm rests, and protective covers that must combine a tough surface and a soft feel. 

Integral Skin Foam Protects Fancy Tires, PT, Sep. 2002. 

Semi-flexible foams (or semi-rigid foams) are sometimes classified as subdivisions of flexible foam because the foams have higher load-bearing properties and good compression recovery. Microcellular flexible foams and integral-skin flexible foams may also be classified in this category. In some classifications, however, microcellular foams are classified as elastomers. 

Foamed urethane elastomers are also called microcellular elastomers. The densities are in the range of about 20 to 60 pcf (320 to 960 kg/m. Integral-skin foams having a density of ca. 700 to 1,000 kg/m are sometimes referred to as microcellular elastomers. 

Integral-skin foam is referred to as self-skinning foam or self-skiimed foam. The foams have high-density skin layers and low-density cores. The overall densities vary in the range of about 200 to 1,100 kg/m (12 to 70 px f). 

Integral-skin urethane foams are classified into two types, flexible and rigid. The former foams will be described here, and the latter will be described in the rigid-foam section. 

Preparation of Integral-Skin Flexible Foams. The major polyisocyanates for use in making integral-skin flexible urethane foams are liquid MDl and TDl prepolymers. In order to make light-stable integral-skin foams, aliphatic diisocyanates, e.g., HDl (hexamethylene diisocyanate) and IPDl (isophorone diisocyanate) in modified forms are used. 

---