Resin Manufacture

Different resins are manufactured from different petroleum based feedstocks (Table 1.1). Monomers, compounds which can be used to react with itself or another similar compound or molecule, form polymers. The feedstocks shown in Table 1.1 are either monomers or used to form monomers. For example, ethylene is a monomer for producing polyethylene, and benzene is used to produce styrene, the monomer for polystyrene. 

The glass transition temperature (Tg) refers to the midpoint temperature of a temperature band. When the temperature is above the midpoint, the resin structure is unfrozen and in a rubbery state and will eventually melt with increasing temperature. When the temperature is below the midpoint, the resin is in a hard, glassy condition. 

Polymers are characterized according to many parameters. Some of the more basic characterizations are the molecular weight (MW) of the polymer produced, density and the melt point. The density is affected by the MW of the polymer produced, among other things. The melt flow index (MFI) is a simplified measurement for determining grades 

Polypropylene (PP) The basic structure of homopolymer PP is linked propylene monomer. 

Copolymerization with ethylene also occurs frequently. Hundreds of grades of PP are sold in the U.S. Its density is among the lowest of 1 plastics. 

In addition to the above possible mechanisms the possibility of reaction at OT-positions should not be excluded. For example, it has been shown by Koebner that o- and p-cresols, ostensibly difunctional, can, under certain conditions, react with formaldehyde to give insoluble and infusible resins. Furthermore, Megson has shown that 2,4,6-trimethylphenol, in which the two ortho- and the one para-positions are blocked, can condense with formaldehyde under strongly acidic conditions. It is of interest to note that Redfam produced an infusible resin from 3,4,5,-trimethylphenol under alkaline conditions. Here the two m- and the p-positions were blocked and this experimental observation provides supplementary evidence that additional functionalities are developed during reaction, for example in the formation of quinone methides. 

In the manufacture of novolaks, 1 mole of phenol is reacted with about 0.8 mole of formaldehyde (added as 37% w/w formalin) in the presence of some acid as catalyst. A typical charge ratio would be  

100 parts by weight 70 parts by weight 1.5 parts by weight 

The reaction mixture is heated and allowed to reflux, under atmospheric pressure at about 100°C. At this stage valve A is open and valve B is closed. Because the reaction is strongly exothermic initially it may be necessary to use cooling water in the jacket at this stage. The condensation reaction will take a number of hours, e.g. 2-4 hours, since under the acidic conditions the formation of phenol-alcohols is rather slow. When the resin separates from the aqueous phase and the resin reaches the requisite degree of condensation, as indicated by refractive index measurements, the valves are changed over (i.e. valve A is closed and valve B opened) and water present is distilled off. 

In the case of novolak resins the distillation is normally carried out without the application of vacuum. Thus, as the reaction proceeds and the water is driven off, there is a rise in the temperature of the resin which may reach as high as 160°C at the end of the reaction. At these temperatures the fluid is less viscous and more easily stirred. In cases where it is important to remove the volatiles present, a vacuum may be employed after the reaction has been completed, but for fastcuring systems some of the volatile matter (mainly low molecular weight phenolic bodies) may be retained. 

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Throughout the remainder of this article the term homopolymer refers to Delrin acetal resin manufactured and sold by Du Pont the term copolymer refers to Celcon acetal copolymer resins (registered trademark of Hoechst Celanese Corporation). 

Phosgene (for toluene diisocyanate, dipbenylmetbane diisocyanate, and polycarbonate resin manufacture), cbloroisocyanuric acid, cyanuric cbloride. 

Paraformaldehyde is used by resin manufacturers seeking low water content or more favorable control of reaction rates. It is often used in making phenol—, urea—, resorcinol—, and melamine—formaldehyde resins. 

Melt Viscosity. Viscosities of resins at standard temperatures yield information about molecular weight and molecular weight distribution, as weU as valuable information with respect to appHcation logistics. Some customers prefer to receive resins in molten form. Melt viscosities help to determine the required temperature for a resin to be pumpable. Temperature—viscosity profiles are routinely suppHed to customers by resin manufacturers. In general, a molten viscosity of 1—1.1 Pa-s (1000—1100 cP) or less at process temperatures is convenient for the pumping and handling of molten resin. 

Phenols. The first stable ozone oxidation product of phenol in water is ds ds-raucomc acid, which requires - 2 mol O /mol phenol. In practice, larger dosage levels of ozone are required because other ozone-reactive substances are present in most wastes. Ozone oxidation of phenoHc effluents is employed in paper mills, coke mills, oil refineries, and thermoplastic resin manufacture, producing effluents that are safe to freshwater biota (122,123) (see Lignin Pulp). 

U.S. phenoHc resin manufacturers include AHiedSignal Inc./Bendix Ashland Chemical, Inc. Borden, Inc. Dexter Corp. Dyno Polymers Georgia-Pacific Corp. Neste Resins Corp. Occidental Chemical Corp. Owens-Corning Corp. Plastics Engineering Co. PMC, Inc. Resinoid Engineering... 

Fig. 2. Functional end groups and solution viscosity during polyester resin manufacture. Acid value is defined as the milligrams of KOH required to neutralize 1 g of polymer hydroxyl value is defined as the milligrams of acid equivalent required to neutralize 1 g of polymer. Solution viscosities are...

If the total alkyds consumed in recent years is classified by their dibasic acid component, about 50% belongs to the unmodified phthaHc type, about 28% modified phthaHc type, about 13% based on isophthaHc, and the balance based on polybasic acids other than phthaHc or isophthaHc. The top alkyd resin manufacturers in the U.S. are Cargill, Reichhold, a subsidiary of Dainippon Ink Chemicals, Inc., and Spencer KeUog, now a part of NL Industries, Inc. The median price (52,53), of general types of alkyd resin, soHds base, was 1.98/kg in Nov. 1990 compared to about 440 in 1955, about 660 in 1975, and about 1.54 in 1983, reflecting the increases in raw material cost. 

Several factors were utilized in bringing formaldehyde release down. In particular, resin manufacturer executed more careful control of variables such as pH, formaldehyde content, and control of methylolation. There has also been a progressive decrease in the resin content of pad baths. The common practice of applying the same level of resin to a 50% cotton—50% polyester fabric as to a 100% cotton fabric was demonstrated to be unnecessary and counter productive (89). Smooth-dry performance can be enhanced by using additives such as polyacrylates, polyurethanes, or siUcones without affecting formaldehyde release. 

Compound Manufacture. AH PVC must be compounded before used. Por the wide variety of requirements where PVC performs, it is usually not feasible to maintain a technical compounding knowledge at the user level. Often processors and original equipment manufacturers (OEMs) purchase compound already balanced to meet the range of properties required and to do the best job economically. Some resin manufacturers are integrated to supply these compounds. 

Benzoin, [119-53-9] 2-hydroxy-2-phenylacetophenone, CgH CH(OH)COCgH (mp, 133—137°C bp, 343—344°C at 101.3 kPa), is formed by the self-condensation of benzaldehyde in the presence of potassium cyanide. It is used on a small scale as a polymerization catalyst in polyester resin manufacture. 

Vehicles are selected by two methods. In one a concentrate is designed directiy for a resin system, the resin itself, or a compatible resin. Thus when the concentrate is made there is a minimal effect on the properties of the final color. In PVC, often a plasticizer such as dioctyl phthalate (DOP) is used. In the other method, concentrates are made with a commercial universal concentrate vehicle. Concentrate manufacturers and some resin manufacturers have developed vehicles that can incorporate many types of colorants and can be used across many classes of polymers without adversely affecting final product performance. 

Most of the resin systems used in commodity composites are slight modifications of the standard commercial mol ding grade material. Usually certain selected properties, such as purity or molecular weight range or distribution, are enhanced or carehiUy selected. In addition, special additives, such as flow controllers, thermal stabilizers, or antioxidants, are often added by the resin manufacturer prior to shipment. Many of the conventional or commodity-type resins used in thermoplastic composites are Hsted in Table 1 and the preparation of each of these is described. AH resins and blends described in the hterature are not Hsted, and the synthesis described is not the only procedure available, but is usually the most common commercial process. 

Paint and varnish manufacturing Resin manufacturing closed reaction vessel Varnish cooldng-open or closed vessels Solvent thinning Acrolein, other aldehydes and fatty acids (odors), phthalic anhydride (sublimed) Ketones, fatty acids, formic acids, acetic acid, glycerine, acrolein, other aldehydes, phenols and terpenes from tall oils, hydrogen sulfide, alkyl sulfide, butyl mercaptan, and thiofen (odors) Olefins, branched-chain aromatics and ketones (odors), solvents Exhaust systems with scrubbers and fume burners Exhaust system with scrubbers and fume burners close-fitting hoods required for open kettles Exhaust system with fume burners... 

At one time the requirement for phenol (melting point 41°C), eould be met by distillation of eoal tar and subsequent treatment of the middle oil with eaustic soda to extraet the phenols. Such tar acid distillation products, sometimes containing up to 20% o-cresol, are still used in resin manufacture but the bulk of phenol available today is obtained synthetically from benzene or other chemicals by such processes as the sulphonation process, the Raschig process and the cumene process. Synthetic phenol is a purer product and thus has the advantage of giving rise to less variability in the condensation reactions. 

The method for producing formaldehyde was described in Chapter 19. In aminoplastics manufacture it is used in the form of formalin (36-37% w/w CH2O). As in the case of phenolic resin production, formalin with both high and low methanol content is used according to the needs of the manufacturer. The low methanol content formalin is more reactive but is also less stable and must be used soon after its preparation. For this reason some resin manufacturers prefer to use formalin with a high 7-10%) methanol content. 

Since both phenol and acetone are available and the bis-phenol A is easy to manufacture, this intermediate is comparatively inexpensive. This is one of the reasons why it has been the preferred dihydric phenol employed in epoxide resins manufacture. Since most epoxide resins are of low molecular weight and because... 

Aluminium chloride Resin manufacture by polymerization of low molecular-weight hydrocarbons Friedel-Crafts reactions to manufacture detergent alkylate, agrochemicals, drugs Irritation due to formation of HCI with moisture... 

It is traditional to divide phenolics into two main categories. These are novolacs and resoles. This system of classification is consistent with the division of applications as well as the compositions and conditions of resin manufacture. Novolacs are used primarily in the molding industries and electronics applications. Resoles are used primarily as binders for other materials. 

Table 3 lists the selected properties [16] that we have measured for several commercially available acrylate resins manufactured by the Sartomer Company and the Rohm and Haas Company. The resins were cured in an AECL Gammacell Model 240. The temperature rise was measured for an 8-g sample using Acsion s (formerly AECL Radiation Applications Branch) Gamma Calorimetry method [17]. All of this information is being used to evaluate the applicability of EB-cured acrylate adhesives for repairing composite structures. Combinations of these adhesives can be used to create electron-curable adhesives suitable for composite repair. 

Conversations with engineers of plastics resin manufacturers. 

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