Formaldehyde acetal copolymers

Acetal homopolymers are polymerized from purified anhydrous formaldehyde. Acetal copolymers are copolymerized from cychc 1,3,5-tri-oxane cychc trimer (CsHeOa) of formaldehyde, tjrpically with a cychc ether comonomer such as ethylene oxide [1]. Ethylene glycol is the product of hydrolysis of ethylene oxide. 

The polymer also can be made from trioxane (the trimer of formaldehyde), usually as a copolymer with ethylene oxide. The —CH2CH2— fragments in the copolymer chain prevent depolymerization acetal copolymer was developed by Celanese (10). 

The first commercially available acetal resin was marketed by Du Pont in 1959 under the trade name Delrin after the equivalent of ten million pounds had been spent in research or polymers of formaldehyde. The Du Pont monopoly was unusually short lived as Celcon, as acetal copolymer produced by the Celanese Corporation, became available in small quantities in 1960. This material became commercially available in 1962 and later in the same year Farbwerke Hoechst combined with Celanese to produce similar products in Germany (Hostaform). In 1963 Celanese also combined with the Dainippon Celluloid Company of Osaka, Japan and Imperial Chemical Industries to produce acetal copolymers in Japan and Britain respectively under the trade names Duracon and Alkon (later changed to Kematal). In the early 1970s Ultraform GmbH (a joint venture of BASF and Degussa) introduced a copolymer under the name Ultraform and the Japanese company Asahi Chemical a homopolymer under the name Tenal. 

Poly(vinyl alcohol) is utilized as a component of starch-based adhesives.11121114 Other patents report the use of partially oxidized starch,1115 dextrins,1116 dextrins and urea,1117 borax,1118 boric acid,1119 and vinyl methyl ether-maleic acid copolymers.1120 Other patents indicate the use of poly (vinyl alcohol) with partially hydrolyzed poly(vinyl acetate),1121 nonhy-drolyzed poly(vinyl acetate),1122 and poly(vinyl chloride).1123 A few patents have reported such poly acrylic additives as poly (acrylic acid)1124 and its salts,1125 poly(acrylamide),1126 1127 A-methylacrylamide or poly(A-acryl-amide),1128 and polyethyleneimine.1129 Polystyrene has also been used,1130 as well as more complex copolymers such as a maleic acid monobutyl ester-methyl vinyl ether copolymer, together with dextrin and polyacrylamide),1131 carboxylated ethyl acrylate-styrene zinc salt copolymer,1132 ethylene-methyl acrylate-vinyl acetate copolymer,1133 vinyl acetate-vinyl pyr-rolidone copolymer,1134 and ethylene-vinyl acetate copolymer.1135 Some adhesives are compounded with SBR latex1136 1138 and phenol-formaldehyde resins.1139... 

Stable acetal copolymers of formaldehyde, called Hostoform and Celcon were also produced commercially by the cationic copolymerization of formaldehyde with ethylene oxide — ... 

Reduction of acetals with NaBH4 was reported,1369 but no applications of the products were given. Crosslinking of starch acetals with epichlorohydrin and similar compounds was also described.1370 A urea-formaldehyde-starch copolymer reacted with hydrogen peroxide and Cu(II) catalysts, thereby producing a starch solution with improved stability of viscosity.1371... 

VdC/EA/MMA teipolymer (latex) Vinyl chloride/vinyl acetate copolymer Vinylidene chloride Vinylidene chloride/vinyl chloride copolymer Formaldehyde Vinyl chloride Epichlorbhydrin Polyvinyl chloride (latex) Polyvinyl chloride (general) Thermoplastic polyurethane Polycarbonate (flame resistant) Polyurethane flexible foam Polycarbonate (general) Polyurethane rigid foam Acrolein MDI Phosgene TDI... 

PREPARATIVE TECHNIQUES The homopolymer is prepared by anionic polymerization of purified formaldehyde with the addition of an initiator such as an amine, phosphine, or metal alcohol. The copolymers are manufactured commercially by copolymerization of trioxane, the cyclic trimer of formaldehyde, with small amounts of a comonomer. T5qjically, acetal copolymer reisns have 95% or more oxymethylene units. 

Ultraform W 2320] Ultraform W2320-003] Ultraform W2540X, Ultraform Z 2320-003] Ultraform Z 2330-003. See Acetal copolymer Ultrahold 8 Ultrahold Strong. See Acrylates/t-butylacrylamide copolymer Ultralac N. See Tosylamide/formaldehyde resin... 

Styrene/butadiene polymer Styrene/methyl methacrylate copolymer Styrene/a-methyl styrene resin Tall oil rosin Tallow amide Terpene resin Tetrasodium pyrophosphate Trimethylolpropane Urea-formaldehyde resin Urea-formaldehyde resin, butylated Vinyl chloride/vinyl acetate copolymer Vinyl chloride/vinylidene chloride copolymer coatings, food-contact acrylate ester copolymer Sodium borate... 

Polyacetal can be divided into two basic types, acetal homoploymer and acetal copolymer. Both homopolymer and copolymer are available in a range of molecular weights (M = 20 000-100 000). The homopolymer is a polymer of formaldehyde with a molecular structure of repeated oxymethylene units (Staudinger, 1932). Large-scale production of polyformaldehyde, i.e. polyacetal, commenced in 1958 in the USA (US Patent 2 768 994,1956) (British patent 770 717,1957). Delrin (1959) was the first trade mark for this polymer by Du Pont Company. The copolymers were introduced by the Celanese Corporation of America, and the first commercial product named Celcon (1960). One of the major advantages of copolymerization is to stabilize polyacetal because the homopolymer tends to depolymerize and eliminate formaldehyde. The most important stabilization method is structural modification of the polymer by, for example, copolymerization with cyclic ether. 

Phenylene oxide-based resins (Noryl ) epoxy, polyisocyanate, polyvinyl butyral, nitrile rubber, neoprene rubber, polyurethane rubber, polyvinyUdene chloride, and acrylic. Polyethylene-nitrile rubber, polyisobutylene rubber, flexible epoxy, nitrile-phenolic, and water-based (emulsion) adhesives. Polystyrene for these foams (expanded polystyrene (EPS)), aromatic solvent adhesives (e.g., toluol) can cause collapse of the foam cell walls. For this reason, it is advisable to use either 100% solids adhesives or water-based adhesives based on SBR or polyvinyl acetate. Specific adhesives recommended include urea-formaldehyde, epoxy, polyester-isocyanate, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, and reclaim rubber. Polystyrene foam can be bonded satisfactorily with any of the following general adhesive types ... 

Phenolic epoxy, polyester-isocyanate, polyvinyl acetate, vinyl chloride-acetate copolymer, polyvinyl formal-phenolic, nitrile rubber, nitrile rubber-phenolic, reclaim rubber, neoprene rubber, polyurethane rubber, butyl rubber, melamine-formaldehyde, neoprene-phenolic, and polyvinyl formal-phenolic. 

Water-based dispersions or emulsions such as polyvinyl acetate, acrylics, polyvinyl chloride and polyvinyl alcohol with plasticizers and tackifiers. In addition, this range can include urea formaldehyde and phenolic adhesives, resins, natural adhesives produced from starch, dextrin, casein, animal glues (see Polyvinyl alcohol in adhesives, Phenolic adhesives single-stage resoles. Phenolic adhesives two-stage novolacs. Animal glues and technical gelatins) and rubber latex (see Emulsion and dispersion adhesives). Solvent-free 100% solids such as polyurethane. Hot melt adhesives include Ethylene-vinyl acetate copolymers, polyolefins, polyamides, polyesters with tackifiers and waxes. More recent additions include cross-linkable systems. 

The Desmocoll polymers show compatibility with some or all of the following polymers to the extent that they give clear solutions and films phthalic resins, xylene-formaldehyde resin, cyclohexanone-formaldehyde resin, highly chlorinated terphenyl, terpene-phenolic resin, acetyl cellulose, nitrocellulose, nitrile rubber, chlorinated PVC, vinyl chloride-vinyl acetate copolymer, rosin esters and coumarone resin. 

The most common types of acetal polymers are the acetal homopolymer (Delrin by Du Pont) and the acetal copolymer (Celcon by Hoescht Celanese-Ticona). The homopolymer is produced from polyformaldehyde and the copolymer from trioxane (a crystalline form of formaldehyde). 

Linear, hard, tough synthetic resins produced by the polymerisation of formaldehyde (for acetal homopolymers) or of formaldehyde with trioxane (for acetal copolymers). Acetal resins are also called as polyacetals and are used as substitutes for metals. 

Formaldehyde is a strong electrophile, allowing acetal to polymerize by nucleophilic, anionic, or cationic addition of an alcohol to ketene carbonyl groups. Relatively weak bases such as pyridine initiate anionic addition polymerization cationic addition polymerization is catalyzed by strong acids. When the cyclic trimer trioxane is used as a copolymer to polymerize acetal copolymers, Lewis acids such as boron tiifluoride promote copolymerization. A more fundamental description is polymerization of an aldehyde or ketone -l- alcohol -i- an acid or base catalyst to form hemiac-etal, which further converts to acetal. The hemiacetal reaction is reversible to aldehyde and alcohol. 

Acetal homopolymer has a T oi about 175°C (347°F) and specific gravity of 1.41 g/cc acetal copolymer has a T oi about 165°C (329°F) and specific gravity of 1.42 [5]. Acetal polymers are synthesized entirely from formaldehyde directly, as noted earlier, or by copolymerization of the formaldehyde cyclic trimer (cyclic oligomer) trioxane and cyclic ethers. 

The heat distortion temperature at 1.80 Mpa is the temperature that causes a beam loaded to 1.80 to deflect by 0.3 mm. If the heat distortion temperature is lower than the ambient temperature, -20 C is given. Polymers such as low-density polyethylene, styrene ethylene-butene terpolymer, ethylene-vinyl acetate copolymer, polyurethane, and plasticized polyvinyl chloride distort at temperatures below <50°C, whereas others, such as epoxies, polyether ether ketone, polydiallylphthalate, polydiallyl isophthalate, polycarbonate, alkyd resins, phenol formaldehyde, polymide 6,10 polyimide, poly-etherimides, polyphenylene sulfide, polyethersulfone, polysulfonates, and silicones, have remaikably high distortion temperatures in the range of 150°C to >300 C. Thermomechanical analysis has been used to determine the deflection temperature of polymers and sample loading forces (i.e., plots of temperature vs. flexure). 

Acetal copolymers thermoplastic materials produced by polymerisation of formaldehyde with other monomers, as opposed to polyacetal (qv). 

Polyacetals prepared from formaldehyde are engineering thermoplastics, which have found use in traditional metal applications. Some trade names of these polymers are Delrin acetal homopolymer (DuPont) Celcon acetal copolymer (Celanese/Hoechst) Duracon acetal copolymer (Celanese and Diacel—joint venture) Tenac acetal homopolymer by Asahi Chemical in Japan and Ultraform acetal copolymer jointly by BASF and Degussa, in Germany. The polymers have the basic structure shown below ... 

Polyoxymethylene (Acetal) Acetal resins are derived primarily from formaldehyde although copolymers are common. Endcapping is done to reduce the rate of d rada-tion. These polymers are strong, tough, and stiff, and they have a low coefficient of friction against many materials. They are creep resistant and are extremely resistant to... 

Acetal homopolymer is a highly crystalline thermoplastic manufactured by polymerization of formaldehyde and capping the two ends of the polymer chain with acetate groups (Table 6.2). It is called polyoxymethylene (POM) and has a backbone consisted of repeating —CH2O—units. Acetal copolymers are produced by copolymerization of trioxane and small amounts of a comonomer. The comonomer randomly distributes carbon—carbon bonds in the polymer chain, which stabilizes the resin against environmental degradation. The low cost of acetals compared to other polymers with similar performance and their mechanical, chemical, and electrical properties, allows them to replace metal and other structural materials in many applications. 

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