Integral skin foams

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

Isoderm Urethane integral-skinning foam Upjohn... 

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). 

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. 

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). 

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. 

Properties of Integral-Skin Flexible Urethane Foams. The foam densities of integral-skin foams of commercial products are in the range of about 300 to 950 kg/m and their Shore A hardnesses are in the range of about 90. Shore D hardnesses are about 40 to 90. Figure 13 shows an example of density distribution of integral-skin foams. 

The scope of the applications of integral-skin foams depends mainly on the foam densities, as shown below ... 

The polyether polyols based exclusively on ACN are commercialised because of their high glass transition temperature (T ) of the polyacrylonitrile solid fraction. However, they are not used for production of slabstock foams, but for PU elastomers (microcellular elastomers for shoe soles) and integral skin foams. 

The alkoxylation process is easy to apply to PU foams having a low concentration of urethane and urea groups such as flexible and semiflexible foams, integral skin foams, PU elastomers and so on. Urea groups react in a similar way with urethane groups, with the formation of oxazolidones and amines by an intramolecular alcoholysis of urea groups (reaction 20.15). 

Elastofoam . [BASF BASF AG] Srrft intend polyurethane foam systems for flexfole integral skin foams, arm rests, steering wheels, spoilers. 

Aromatic urethanes have been stabilized by complexation of peroxides in the polymer and the effect of prior y-irradiation has been investigated, on polyurethanes.The ageing of polyurethane coatings has been investigated, and light-stable integral skin foams have been developed for polyurethanes. Creep behaviour of polyurethanes on ultraviolet exposure has also been investigated. ... 

Replacement of upper mold half — PP integral skin foam still a long way from satisfying current standards... 

Other modified AZs have been developed for the manufacture of integral-skin foams by extrusion and injection molding. These contain additives that modify the usual decomposition process of AZ and suppress the formation of cyanuric acid, which causes plateout on the surfaces of molds, dies, and screws. The additives used include zinc oxide and/or silicic acid (a colloidal silica) with a very low water content. The additives also act as nucleating agents, producing a cell structure that is both uniform and fine-celled. 

In-mould coating should be mentioned here for completeness. This technique is widely used for integral skin foam components in PUR, principally in the passenger compartment. It is also used to prime SMC parts, as an aid to producing a Class A finish on the topcoat. The RTM methacrylic resin panels of the Alfa Romeo SZ were in-mould coated to a Class A finish. As this was a specialist vehicle and no other painted panels were involved, the usual problems of reduced production rate and poor colour matching did not apply. 

Usually a combination of catalysts is required to achieve proper structure and properties, especially in applications such as integral skin foams or reaction injection molding (RIM). The mechanism of the catalysis of isocyanate-alochol reaction in presence of amines is assumed to proceed through an activated complex between amine and isocyanate [15,16]... 

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