Polyurethane binder

Chalking also occurs to some extent with several other types of polymers. It does not directly affect corrosion protection but is a concern because it eventually results in a thinner coating. The problem is easily overcome with epoxies, however, by covering the epoxy layer with a coating that contains a UV-resistant binder. Polyurethanes are frequently used for this purpose because they are similar in chemical stfucture to epoxies but are not susceptible to UV breakdown. 

Gun Propellents. Low sensitivity gun propeUants, often referred to as LOVA (low vulnerabUity ammunition), use RDX or HMX as the principal energy components, and desensitizing binders such as ceUulose acetate butyrate or thermoplastic elastomers (TPE) including poly acetal—polyurethane block copolymers, polystyrene—polyacrjiate copolymers, and glycidyl azide polymers (GAP) to provide the required mechanical... 

The mixed Hquid is pumped into the area, where it cures and forms a slab. It may be poured in two layers to eliminate imperfections in the base. The first layer may be a preformed mbber slab which is glued to the base, or a mixture of reground mbber and binders or mbber and polyurethane. A textured surface maybe imparted to the second coat with sand or chips. 

Water-borne adhesives are preferred because of restrictions on the use of solvents. Low viscosity prepolymers are emulsified in water, followed by chain extension with water-soluble glycols or diamines. As cross-linker PMDI can be used, which has a shelf life of 5 to 6 h in water. Water-borne polyurethane coatings are used for vacuum forming of PVC sheeting to ABS shells in automotive interior door panels, for the lamination of ABS/PVC film to treated polypropylene foam for use in automotive instmment panels, as metal primers for steering wheels, in flexible packaging lamination, as shoe sole adhesive, and as tie coats for polyurethane-coated fabrics. PMDI is also used as a binder for reconstituted wood products and as a foundry core binder. 

In 1993, a total of over 6 x 10 t of polyurethanes were consumed worldwide (Table 8). The flexible foam market in the United States totaled 932,000 tons in 1994. Flexible slab foam is used predominantly in furniture, carpet underlay, and bedding molded foam is used extensively in transportation. Carpet underlay is manufactured from either virgin or scrap polyurethane foam, which is combined with a binder adhesive. The consumption of flexible polyurethane foam in the various U.S. markets in 1994 is shown in Table 9. 

Glassy, or vitreous, carbon is a black, shiny, dense, brittle material with a vitreous or glasslike appearance (10,11). It is produced by the controUed pyrolysis of thermosetting resins phenol—formaldehyde and polyurethanes are among the most common precursors. Unlike conventional artificial graphites, glassy carbon has no filler material. The Hquid resin itself becomes the binder. 

This includes wire enamels on a base of polyvinyl formal, polyurethane or epoxy resins as well as moulding powder plastics on phenol-formaldehyde and similar binders, with cellulose fillers, laminated plastics on paper and cotton cloth base, triacetate cellulose films, films and fibres of polyethylene terephthalate. 

Paints are complex formulations of polymeric binders with additives including anti-corrosion pigments, colors, plasticizers, ultraviolet absorbers, flame-retardant chemicals, etc. Almost all binders are organic materials such as resins based on epoxy, polyurethanes, alkyds, esters, chlorinated rubber and acrylics. The common inorganic binder is the silicate used in inorganic zinc silicate primer for steel. Specific formulations are available for application to aluminum and for galvanized steel substrates. 

Solvent resistance This varies from very poor (for chlorinated rubbers) to good (for polyurethanes). All paint binders have specific susceptibilities and the presence of small quantities of the appropriate solvent in the atmosphere in the region of an item of plant can cause rapid failure. 

Binder Nomenclature Identification a - Polyvinyl butyral resin - Monsanto Co b - Hexafluoropropylene/vinylidme. fluoride 1 2 c - Polyurethane so in system — B.F. Goodrich Co d - Polytrifluorochloroethylene - 3M Co... 

Polyglycidyl Nit rata (Polyurethane) Propellants (PGN). A series of proplnt compns developed by both JPL of Cal Tech and the Aerojet-General Corp in the late 1950 s (Refs 2 3), using as the binder fuel a polyurethane resin prepd from PGN. JPL used either Amm Nitrate or Amm Perchlorate as the oxidizer (Ref 2), while Aerojet used Amm Perchlorate with plasticizers such as 4-Nitrazapentanonitrile (NPN) and 2,2-Pentanoate (TNENP) in a plasticizer-to-binder wt ratio of 0.6 (Ref 3). 

Polymerized Alcohols. Polyhydric alcohols (qv) such as pentaerythritol, sorbitol and glycerin can be used as the polyol component of polyethers (qv) which are used as expl and propint binders. Polyoxypropylene derivs of sorbitol have been employed extensively as components of polyurethane resins (qv), also employed as a propint binder... 

Composite proplnts, which are used almost entirely in rocket propulsion, normally contain a solid phase oxidizer combined with a polymeric fuel binder with a -CH2—CH2— structure. Practically speaking AP is the only oxidizer which has achieved high volume production, although ammonium nitrate (AN) has limited special uses such as in gas generators. Other oxidizers which have been studied more or less as curiosities include hydrazinium nitrate, nitronium perchlorate, lithium perchlorate, lithium nitrate, potassium perchlorate and others. Among binders, the most used are polyurethanes, polybutadiene/acrylonitrile/acrylic acid terpolymers and hydroxy-terminated polybutadienes... 

T.L. Boggs et al, AIAA J 8 (2), 370-72 (1970) CA 72, 113371 (1970) Scanning electron microscopy is used to study the surface structure of solid proplnts, prepd from AP (1) and polyurethane or caiboxylated polybutadiene. Polyurethane proplnts are self-extinguish-ing at high pressure due to the flow of molten binder over I crystals. I crystals formed a thin surface melt with gas liberation in the molten phase... 

Both pigmented and unpigmented polyurethane paints have been prepared using a polyester resin containing hydroxyl functional groups and the biuret trlmer of hexamethylenedllsocyanate as a crosslinker. The molar ratio of hydroxyl/isocyanate has been chosen 1.0 and the pig-ment/binder ratio 0.6. 

Polyurethanes are used in many other applications, which we do not have room to discuss. These applications include paints, varnishes, adhesive binders for chipboard and plywood, hoses, timing belts, athletic tracks and playing surfaces, and the encapsulation of electrical components. 

PPG bildet zusammen mit Diisocyanaten Polyurethane als Binder in - Verbundtreibsatzen (..composite propellants 1). 

Die heute gebrauchlichen hochpolymeren Binder sind Polysulfide ( PS ), Polybutadien-Acrylsaure ( PBAA ), Polybutadien-Acrylsaure-Acrylonitril ( PBAN ), Polyurethan ( PU ) und Polybutadien mit Carbo-xyl-Endgruppen ( CTPB ) und mit Hydroxylendgruppen ( HTPB ). 

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