2022 Raw Materials, Chemicals, Polymers, and Additives Handbook

Resins and Base Polymers, A-E

Acrylic Resins

Acrylic resins are prepared by polymerizing acrylate and methacrylate resins. A range of homopolymers and copolymers is available, ranging from simple plastics like polymethylmethacrylate to complex copolymers incorporating several monomers. Uses range from clear plastics and floor polishes to solvent solutions or emulsions used in both pressure-sensitive and liquid adhesives for a wider range of applications, including packaging, carpet manufacture, and construction. The solid resins can also be used as inert thickeners in adhesives like cyanoacrylates and an aerobics.

Acrylic Resins, Acrylic Copolymers

A copolymer is a polymer that is derived from more than one species of monomer. (See also Acrylic Resins.)

Acrylic Resins, Ethylene-Acrylic Ester Copolymers

Copolymer of ethylene and acrylic ester.

Acrylic Resins, Ethylene-Acrylic Ester-GMA Terpolymers

Terpolymer of ethylene, acrylic ester, and glycidyl methacrylate (GMA).

Acrylic Resins, Ethylene-Acrylic Ester-Maleic Anhydride Terpolymers

Terpolymer of ethylene, acrylic ester, and maleic anhydride.

Acrylic Resins, Ethylene-n-Butylacrylate Copolymers

Copolymer of ethylene and n-butylacrylate.

Acrylic Resins, Polymer Emulsions

Polymer emulsions consist of minute particles of polymer dispersed in water.

Acrylic Resins, Solid

Solid acrylic resins are comprised completely of solid content. They can be used as inert thickeners in adhesives like cyanoacrylates and an aerobics.

Acrylic Resins, Solution

(See Acrylic Resins.)

Acrylic Resins, Water-Reducible

Water-reducible resins can be useful for waterborne and solvent-based inks, adhesives, powder coatings, and anti-corrosive coatings.

Alkyd Resins

Alkyd resins are the reaction product of an oil or fatty acid, polyol(s), and polyacids. These polymers are supplied in solvents and can cure by reaction with oxygen or amino-based crosslinking resins to form tough, durable films. The choice and amount of oil in the polymer determines the dry rate and solubility of the polymer in aliphatic solvents.

Long (over 60%) and medium (40-60%) oil alkyds are supplied in low-odor aliphatic solvents and are suitable for architectural and maintenance finishes. Short (under 40%) oil alkyds are supplied in aromatic solvents and are used in fast air-dry and bake finishes. Alkyds can also be modified or co-reacted with many other material types (rosin, phenolic, urethane, vinyl monomers, etc.). The precise combination of the many possible ingredients, together with careful control of the reaction, influences the final properties of the alkyd produced.

Alkyd Resins, Water-Reducible

Water-reducible resins can be useful for waterborne and solvent-based inks, adhesives, powder coatings, and anti-corrosive coatings.

Amorphous Polypropylene

Polypropylene without a clearly defined shape or form.

Block Copolymers

Block copolymers are formed when the two monomers comprising the copolymer form groups (blocks) of repeating units.

Butadiene-Acrylonitrile Rubber

Also known as NBR, a synthetic rubber copolymer of acrylonitrile and butadiene.

Butyl Rubber

Butyl rubber is mainly polyisobutylene, but with about 1-3% polyisoprene added to it so that it is possible to crosslink it by conventional means. It is a little darker in color, with an available molecular weight range of around 350,000-450,000. Thus, much of what is said about polyisobutylene applies to butyl rubber, recognizing the molecular-weight difference between the two. It is also very stable to aging and ultraviolet light.

In addition to standardized grades, some specialized grades are manufactured. Should some specific end use call for a variation from the ordinary, elastomer manufacturers should be contacted. One major source of butyl rubber for underground pipe-wrap tapes was reclaim butyl from automotive inner tubes, but with the advent of tubeless tires this source has been reduced to truck inner-tube reclaim, along with some mechanical goods and one or two other minor sources. Butyl latex has been used as a base for prime-coat formulae for polyolefin films where it shows preferential bonding.²

Chlorinated Rubber

White powder formed by reacting carbon tetrachloride with chlorine.

Cyanoacrylates

Any of a number of cyanoacrylic esters that quickly cure to form a strong bond.

Dispersions

The term dispersion is normally used to describe a solid finely dispersed in a liquid. In contrast to solutions, dispersions are heterogeneous on a microscopic scale. Colloid chemists refer to them as “sols.” In practice, many materials can be supplied as dispersions, including things like polyurethane adhesive dispersions in water.

Dispersions are also used widely in plastics and rubber processing, where companies supply master batches of additives in water, plasticizers, or process oils. Typical additives are colorants, slip aids, antioxidants, polymer accelerators, UV inhibitors, and polymer stabilizers. Some manufacturers of synthetic latex adhesives have started to call their products dispersions to avoid using the term latex. This is to avoid association with the latex allergy issue, which is in fact unique to natural rubber latex.

Epoxy Films and Paste

Epoxy in film or paste form.                

Epoxy Flexibilizers/Diluents

Flexibilizers improve peel and impact strength generally by allowing the adhesive to deform under the application of stress. They reduce mechanical damage by lowering modulus or plasticization, which allows the adhesive to become distorted.

The primary function of a diluent in an epoxy resin formulation is to reduce its viscosity to either make it easier to compound with fillers, improve filler loading capacity, or to improve application properties.

Epoxy Hardeners

A catalytic or reactive agent used to react with the epoxide group on an epoxy resin to promote, enhance, or control the curing reaction and aid in property development of the final epoxy thermoset. The hardener (also called a curing agent) typically has active hydrogen attached to nitrogen, oxygen, or sulfur. Amine curing agents are the most common and can be primary or secondary, aliphatic or aromatic, or cycloaliphatic. The amines typically have greater than three reactive sites per molecule that facilitate the formation of a three-dimensional polymer network when mixed with the epoxy resin.

Epoxies can be cured in several ways. Single-component epoxies usually contain hardeners like dicyanamide and are cured by heating at moderately high temperatures. Two-component systems can be cured at room temperature or higher by a condensation mechanism involving the glicydyl groups of the epoxy resins and primary or secondary amines. Strong acids or acid-generating molecules such as anhydrides can also act as hardeners.

Epoxy Resins

A thermosetting resin based on the reactivity of the epoxide group. One type is made from epichlorohydrin and bisphenol A. Aliphatic polyols such as glycerol may be used instead of aromatic bisphenol A. Molecules of this type have glycidyl ether structures, --OCH₂CHOCH₂, have many hydroxyl groups in the terminal positions, and cure readily with amines. Another type is made from polyolefins oxidized with peracetic acid. These have epoxide groups within the molecule as well as in terminal positions, and can be cured with anhydrides, but require high temperatures.

Many modifications of both types are made commercially. Halogenated bisphenols can be used to add flame-retardant properties. The reactive epoxies form a tight crosslinked polymer network and are characterized by toughness and good adhesion, corrosion resistance, chemical resistance, and dielectric properties.

Epoxy Resins, Liquid/Solution

Liquid hydrocarbon resins are used almost exclusively for solvent-free systems. The main reasons for their application are improved miscibility of polyol and aromatic isocyanate, adjustment of mix ratio, increased moisture resistance, greater water repellent properties, improved adhesion and better flexibilization. (See also Hydrocarbon Resins.)

Epoxy Resins, UV-Curing

Materials that are polymerized and cured by ultraviolet light.

Ethylene-Propylene Rubber

EPM is a type of synthetic elastomer.