High-resilience flexible foams

With amine initiators the so-called self-catalyzed polyols are obtained, which are used in the formulation of rigid spray foam systems. The rigidity or stiffness of a foam is increased by aromatic initiators, such as Mannich bases derived from phenol, phenolic resins, toluenediamine, or methylenedianiline (MDA). In the manufacture of highly resilient flexible foams and thermoset RIM elastomers, graft or polymer polyols are used. 

The polyisocyanates which can be used for preparing isocyanate-based foams are mainly aromatic compounds and some aliphatic or aralkyl polyisocyanates. TDI (toluene diisocyanate) is widely used for flexible foams. Pure MDI (diphenylmethane diisocyanate) is used for elastomers and coatings. Modified TDI and modified MDI are used for high-resilience flexible foams. Polymeric isocyanates (polymeric MDI or oligomeric MDI) are mostly used for preparing rigid urethane and isocyanurate foams, and in part, for preparing flexible and semi-flexible foams. 

Classification. Flexibie urethane foams have the largest market of all polyurethane products. The production properties and applications of various flexible urethane foams are described in the following sections. Flexible urethane foams are defined as open-cell urethane foams having the property of complete recovery immediately after compression. They can be classified into two kinds, i.e., polyether foams and polyester foams. Polyether foams are further classified as follows conventional flexible foams, high-resilience flexible foams (HR foams), cold-molded foams, super-soft foams, and viscoelastic foams. 

Crude MDI and PAPI are especially used in highly crosslinked polyurethanes, such as rigid polyurethane foams. Polymeric MDI have lower vapour pressures than TDI. Mixtures of TDI with polymeric MDI are also used in many applications, (e.g., in high resilience flexible foams). Aliphatic diisocyanates have a much lower reactivity than aromatic isocyanates. The most important aliphatic diisocyanates are presented in Figure 2.5 [1-3, 6, 23-25] ... 

Dimethylaminoethoxy)ethanol N,N-Dimethyl-diglycolamine EINECS 216-940-1 Ethanol, 2-(2-(dimethylamino)ethoxy)- NSC 3146 Texacat ZR-70, Catalyst for polyurethane molded high resilience flexible foam, ether slabstock, packaging foam. Texaco. 

CCRIS 6690 1,4-Dimethylpipera2ine EINECS 203-412-0 Lupelazine N.N -Dimethylpiperazine NSC 41177 Piperazine, 1,4-dimethyl- Texacat DMP. Catalyst for polyurethane molded high resilience flexible foam, ester slabstock. Liquid bp = 131" d " = 0,8600 very soluble in H2O, EtOH, Et20, Texaco. 

Uses Catalyst for PU (RIM, high-resilience flexible foam heat stabilizer for PVC Trade Name Synonyms Therm-Chek 840 [Ferro/Polymer Addit. http //www.ferro.com]... 

N,N,N, N -Tetramethyl-1,3-butanediamine catalyst, high-resilience flexible foam Dibutyltin bisisooctyl thioglycolate Dioctyltin diisooctylthioglycollate catalyst, hydration Silver... 

In the manufacture of highly resilient flexible foams and some thermoset RIM elastomers, graft or polymer polyols are used. Graft polyols are dispersions of free-radical-polymerized mixtures of acrylonitrile and styrene partially grafted to a polyol. Polymer polyols are available from BASF, Dow, and Union Carbide. In situ polyaddition reaction of isocyanates with amines in a polyol substrate produces polyharnstoff dispersion (PHD) polyols, which are marketed by Bayer (53). In addition, blending of polyether polyols with diethanolamine, followed by reaction with TDI, also affords a urethane/urea dispersion (54). The polymer or PHD-type polyols increase the load bearing properties and stiffness of flexible foams. Interreactive dispersion polyols are also used in RIM applications where elastomers of high modulus, low thermal coefficient of expansion, and improved paintability are needed. 

Uses Surfactant for use in high resiliency flexible foams in TDI, MDI / TDI and MDI based cold-cure flexible molded PU systems cell regulator and surface stabilizer Features Eliminates basal cell formation low vise. exc. vent stability and foam surface appearance, even at broad mold temp, latitude (55-70 C)... 

The effect of the balance between gas generation and polymer formation on foam-cell structure is shown in Figure 12. A formulation for high-resilience, flexible urethane foams is shown in Table 20. 

Priester et al (141) have found a method of controlling the amine-isocyanate reaction by using substituted-amine-terminated polyethers, and they obtained high-resiliency polyurea foams by this method. Ashida et al (81) prepared low-density flexible polyurea foams by using a primary-amine-terminated polyether (Jefhunine D-2000, Texaco Chemical). 

ASTM D 3770-79 (1985) Standard Specification for Flexible Cellular Materials - High Resilience Polyurethane Foam (HR), 2 pp (Comm D-11)... 

The growth of urethane foam was accelerated in 1972 with the development of high resilience flexible urethane foam for automotive deep foam seating. One of the first significant uses... 

Applications Cold moulded high resilience flexible PU foams for car seats, semiflexible ... 

In order to avoid these extremely dangerous phenomena, methods of treatment of PO with adsorbents (active carbon, charcoal, attapulgite, diatomaceous earth) were devised. By the treatment at room temperature of PO with these adsorbents (0.1-1% adsorbent in liquid PO), after a short contact time of about 15 minutes the high MW polyether is almost quantitatively retained by adsorption. The PO resulting after the filtration of the solid adsorbent is practically free of high MW polymers, and the polyethers obtained with the treated PO can be used to manufacture resilient flexible foams which will not collapse, with high rise and free of blow hole formation. 

PHD polyols are successfully used for high resilience flexible PU foams (made by the cold cure process), for continuous slabstock flexible PU foams and for elastomers obtained especially by reaction injection moulding (RIM) technology. 

Chem. Descrip. Triettrylenediamine (33%) in dipropylene glycol (67%) Uses Catalyst for PU high resiliency flexible and rigid slabsto and moidkl foam, elastomers, shoe soles, coating Properties Liq. sol. in water sp.gr. 1.13 (24 C) vise. 100 cps (24 C) vapor pressure 2 mm Hg (38 C) hyd. no. 560 flash pt. (PMCC) > 110 C Dabco Crystalline [Air Prods/Perf. Chems.)... 

Uses Stabilizer/surfactant for flexible and semiflexible molded and slabsfock high-resiliency PU foam... 

Uses Surfactant for the production of high resilience flexible slabstock foams, esp. 

Uses Surfactant for use in high-resiliency, flexible polyurethane foam based on high m.w. polyols and polymeric isocyanates Properties Cl. liq. sp.gr. 0.919 vise. 5.0 cs flash pt. (CC) 138 C ref. index 1.3966. Dabco DC2517 [Air Prods./Perf. Chems,]... 

Commonly used isocyanates are toluene dhsocyanate, methylene diphenyl isocyanate, and polymeric isocyanates. Polyols used are macroglycols based on either polyester or polyether. The former [poly(ethylene phthalate) or poly(ethylene 1,6-hexanedioate)] have hydroxyl groups that are free to react with the isocyanate. Most flexible foam is made from 80/20 toluene dhsocyanate (which refers to the ratio of 2,4-toluene dhsocyanate to 2,6-toluene dhsocyanate). High-resilience foam contains about 80% 80/20 toluene dhsocyanate and 20% poly(methylene diphenyl isocyanate), while semi-flexible foam is almost always 100% poly(methylene diphenyl isocyanate). Much of the latter reacts by trimerization to form isocyanurate rings. 

Flexible foams are used in applications where a high degree of resiliency is required with moderate load-bearing capacity. Essentially all foam seating is urethane based, including the furniture and automotive markets. Other examples are packaging, textiles, filters, sports equipment, and recreational items. 

The resulting slate of polyols has been demonstrated in conventional flexible slabstock foam [143], viscoelastic foam [144], and high resiliency slabstock and molded foams [145],... 

By crosslinking, the viscosity of EVA at high temperatures is increased and the individual cells are kept in a stable condition without rupture or agglomeration. A low density microcellular foam can be thus obtained. By selecting the vinyl acetate content, the EVA foam is flexible and highly resilient with easy coloring and adherent to other materials. The application is used widely in shoe soles, sandals and cushion materials. 

The steric effects in isocyanates are best demonstrated by the formation of flexible foams from TD1. In the 2.4-isomer (4), the initial reaction occurs at the nonhindered isocyanate group in the 4-position. The unsyinmeli ically substituted ureas formed in the subsequent reaction with water are more soluble in the developing polymer matrix. Low density flexible foams are not readily produced from MDi or PMDi enrichment of PMDI with Ihe 2,4 -isomcr of MDi (5) affords a steric environment similar to the one in TDI, which allows the production of low density flexible foams that have good physical properties. The use of high performance polyols based on a copolymer polyol allows production of high resiliency (HR) slabstock foam from either TDI or MDI. 

Flame retardants are incorporated into the formulations in amounts necessary to satisfy existing requirements. There are four main types of flexible slabstock foam conventional, high resiliency, filled, and high load-bearing foam. 

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