Urethane Phenolics

According to Robins and Graham, a two-part phenolic-urethane system gives effective wood bonding and also metal bonding. 

Using heat-reactive p-alkylphenolic resins or ortho-ortho resole resins in aromatic solvent and a polymeric isocyanate in the presence of a small amount of tertiary amine, a rapidly curing adhesive system of good overlap shear for both wood and aluminum can be obtained. The best metal and wood adhesive is based on p-cresol or a straight phenolic ortho-ortho resole in combination with a polymeric aromatic isocyanate such as PAPI or Mondur MRS.  

---

The existence of microcells in the structure of oligomeric foams was confirmed by studies on other types of oligomeric foams phenolic polyurethane and urethane-phenolic multicomponent oligomeric foams ... 

In this section, the future developments will be discussed that might be expected in commercial polymer blends comprising at least one of the constituents from the class of commodity polymers. Generally, the commodity polymers considered include polyethylene (and variants LDPE, HOPE, LLDPE, VLDPE and ethylene copolymers), polypropylene (PP), ethylene-propylene rubber (EPR and EPDM), polyvinylchloride (PVC), polystyrene (PS), ABS, and poly(methyl methacrylate) (PMMA). Elastomeric polymers commonly used in tire and associated applications are important in polymer blends as many tire component constructions employ polymer blends to maximize performance. However, these will not be considered here. Thermosetting polymers which could be classified as commodity polymers (urethane, phenolics, epoxies) will also not be covered, but will be mentioned in a later section discussing new polymer blends designed for specific applications (e.g., water based coatings). 

Figure 6. Strength reduction curves for the automatic boil test. (1) Solid wood (2) fast-cure epoxy, slow-cure epoxy, phenolic-resorcinol, urethane, phenol (3) casein, melamine-urea, melamine (4) urethane, urea. After ref. 32.

Thermoset plastics are cross-linked by chemical reaction so that their molecules cannot slip by one anotber. They are rigid when cool and cannot be softened by the action of heat. If excessive heat is applied, thermoset plastics will degrade. Consequently, they are not weldable. Because of their chemical resistance, they cannot be solvent cemented. Thermoset plastics are usually joined by either adhesive bonding or mechanical fastening. Typical thermosetting plastics are epoxy, urethane, phenolic, and melamine formaldehyde. 

Eng. resins incl. olefins, nylons, polyesters thermosets-urethane, phenolic, polyester, etc. RRIM injection molding. 

Urethane formation. See (C) below. This reaction should be used for crystalline derivative formation, and not as a general reaction for phenols. 

Naphthol Antipyrine, camphor, phenol, iron(III) salts, menthol, oxidizing materials, permanganates, urethane... 

Catalysis is usually accompHshed through the use of tertiary amines such as triethylenediamine. Other catalysts such as 2,4,6-/m(/V,/V-dimethylaminomethyl)phenol are used in the presence of high levels of cmde MDI to promote trimerization of the isocyanate and thus form isocyanurate ring stmctures. These groups are more thermally stable than the urethane stmcture and hence are desirable for improved flammabiUty resistance (236). Some urethane content is desirable for improved physical properties such as abrasion resistance. 

Acetoiicetyliition Reactions. The best known and commercially most important reaction of diketene is the aceto acetylation of nucleophiles to give derivatives of acetoacetic acid (Fig. 2) (1,5,6). A wide variety of substances with acidic hydrogens can be acetoacetylated. This includes alcohols, amines, phenols, thiols, carboxyHc acids, amides, ureas, thioureas, urethanes, and sulfonamides. Where more than one functional group is present, ring closure often follows aceto acetylation, giving access to a variety of heterocycHc compounds. These reactions often require catalysts in the form of tertiary amines, acids, and mercury salts. Acetoacetate esters and acetoacetamides are the most important industrial intermediates prepared from diketene. 

Polymers. AH nitro alcohols are sources of formaldehyde for cross-linking in polymers of urea, melamine, phenols, resorcinol, etc (see Amino RESINS AND PLASTICS). Nitrodiols and 2-hydroxymethyl-2-nitro-l,3-propanediol can be used as polyols to form polyester or polyurethane products (see Polyesters Urethane polymers). 2-Methyl-2-nitro-l-propanol is used in tires to promote the adhesion of mbber to tire cord (qv). Nitro alcohols are used as hardening agents in photographic processes, and 2-hydroxymethyl-2-nitro-l,3-propanediol is a cross-linking agent for starch adhesives, polyamides, urea resins, or wool, and in tanning operations (17—25). Wrinkle-resistant fabric with reduced free formaldehyde content is obtained by treatment with... 

The rate of stripping or the stripabiUty on cataly2ed urethane and epoxy resin finishes can be increased by adding formic acid, acetic acid, and phenol. Sodium hydroxide, potassium hydroxide, and trisodium phosphate [10101-89-0] may be added to the formula to increase the stripabiUty on enamel and latex paints. Other activators include oleic acid [112-80-17, trichloroacetic acid [76-85-9], ammonia, triethanolamine [102-71-6], and monoethyl amine. Methylene chloride-type removers are unique in their abiUty to accept cosolvents and activators that allow the solution to be neutral, alkaline, or acidic. This abihty gready expands the number of coatings that can be removed with methylene chloride removers. 

Benzene, toluene, and xylene are made mosdy from catalytic reforming of naphthas with units similar to those already discussed. As a gross mixture, these aromatics are the backbone of gasoline blending for high octane numbers. However, there are many chemicals derived from these same aromatics thus many aromatic petrochemicals have their beginning by selective extraction from naphtha or gas—oil reformate. Benzene and cyclohexane are responsible for products such as nylon and polyester fibers, polystyrene, epoxy resins (qv), phenolic resins (qv), and polyurethanes (see Fibers Styrene plastics Urethane POLYiffiRs). 

One-part urethane sealants (Table 3) are more compHcated to formulate on account of an undesirable side reaction between the prepolymer s isocyanate end and water vapor which generates carbon dioxide. If this occurs, the sealant may develop voids or bubbles. One way to avoid this reaction is to block the isocyanate end with phenol and use a diketamine to initiate cure. Once exposed to moisture, the diketamine forms a diamine and a ketone. The diamine reacts with the isocyanate end on the prepolymer, creating a cross-link (10). Other blocking agents, such as ethyl malonate, are also used (11). Catalysts commonly used in urethane formulations are tin carboxylates and bismuth salts. Mercury salt catalysts were popular in early formulations, but have been replaced by tin and bismuth compounds. 

Asphalt, unmodified Coal tar Coal tar— epoxy Coal tar— nretlianes Epoxy phenolic- baked Epoxy amine- cnred Epoxy ester Fnrfnryl alcohol Phenolics, baked Polyesters (nnsati i-rated) Polyvinyl cliloracetates Vinyl ester Urethanes Vinylidene cliloride Clilorinated rubber... 

Trimethylsilyl trichloroacetate, K2CO3, 18-crown-6, 100-150°, 1-2 h, 80-90% yield.This reagent silylates phenols, thiols, carboxylic acids, acetylenes, urethanes, and /3-keto esters, producing CO2 and chloroform as byproducts. 

Common plasticizers are used to reduce viscosity and to aid adhesion. Most plasticizers commonly utilized in PVC are also used in urethanes. One of the most common plasticizers is diisodecyl phthalate, though many others are used equally effectively. In some cases tackifiers, such as certain esters or terpine phenolics, are utilized to obtain specific adhesion characteristics. 

A hindered phenol is one of the most common antioxidants used in urethanes. This antioxidant traps radicals, which can degrade the polymer chain. The proposed mechanism is as follows [87] ... 

The miotic effect induced by physostigmine lends itself to investigation of the interrelation of chemical constitution and pharmacological action, and Stedman has devoted much attention to this subject. Eseroline is devoid of miotic activity, so that the latter action in physostigmine must be mainly due to the fact that it is a methylurethane, and, since activity only becomes evident in the urethanes of phenolic bases or phenols with a basic side-chain, a basic nucleus for the urethanes appears also to be essential. 

Among the reactions appended to this preparation, the foi-mation of phenylcaibiniide from phenyl mustard oil is desciibetl. It should be noted that phenyl carbimide, like the thiocarbiniide, unites with ammonia, amines, and more especially with alcohols and phenols. The bases yield urea derivatives the alcohols and phenols foim urethanes. 

Silicone alkyds Urethane alkyds Epoxy esters Tung oil phenolic... 

When samples of about 1 cm were taken from a single cast film of 100 X 200 mm of a number of paint and varnish films, their resistances varied with the concentration of potassium chloride solution in one of two ways (Fig. 14.2). Either the resistance increased with increasing concentration of the electrolyte (inverse or / conduction) or the resistance of the film followed that of the solution in which it was immersed (direct or D conduction). The percentage of / and D samples taken from different castings varied, but average values for a number of castings were 50% D for the pentaerythritol alkyd and the tung oil phenol formaldehyde varnishes, 57% for urethane alkyd, 76% for epoxypolyamide and 78% for polyurethane varnishes... 

Certain plastics provide higher strength and stiffness a broad range of properties exit. Even though there are literally over 35,000 plastics available worldwide (for all plastic fabricating processes) only a few hundred are used in RPs. In turn only a few of those are predominantly used in most of the RPs. The thermoplastics (TPs) include principally nylons and polypropylenes, as well as polycarbonates, acetals and polyesters. Thermosets (TSs) include predominantly polyesters as well as epoxies, phenolics and urethanes. 

Synthetic resins Acrylic Alkyd. Chiorobenzols Chlorodiphenyls Chloro-naphthalenes Chlorophenols Cumaron Epoxies Melamine formaldehyde Phenol formaldehyde Polyesters Sulphonamide formaldehyde Urea formaldehyde Urethane Vinyl Others Enzymes derived from B. subtilis... 

---