Materials Handbook

Catalysts

"Initiators," used to cure or cross-link monomers and polymers. Typical types include organic peroxides and hydro-peroxides, sulfur compounds used in rubber vulcanization, and UV initiators used in adhesives and coatings.

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 (aka 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.

Ethyl Ether

A colorless and extremely flammable solvent.

Polyethylene

A commodity thermoplastic produced by the polymerization of ethylene gas. Various polymerization methods lead to polymers with varying degrees of chain branching and thus a varying tendency to crystallize. Highly branched polymers don't crystallize easily and give low-density polyethylene (LDPE), whereas very linear polymers crystallize well and give high-density polyethylene (HDPE). Modern developments include new metallocene catalysts that give polymers with very controllable molecular weights and chain structures, ultra-high-molecular-weight polyethylene and the so-called plastomers, which are copolymers of ethylene with high levels of 1-olefins that give properties intermediate between plastics and elastomers.

Isocyanate resins

A linear alkyd resin lengthened by reaction with isocyanates, then treated with a glycol or diamine to crosslink the molecular chain.

Thiourea

A lustrous white crystalline compound (NH2)2CS, used in various organic syntheses.

Surface conditioners and Modifiers

A material used to make a surface suitable for adhesive joining.

Dicyandiamide

A solid curing agent for epoxy resins.

Surfactants and dispersing Agents

A surface-active compound that reduces surface tension when dissolved in water or water solutions, or that reduces inter-facial tension between two liquids, or between a liquid and a solid. There are 3 categories of surface-active agents: detergents, wetting agents and emulsifier. All 3 have the same basic chemical mechanism and differ chiefly in the nature of the surfaces involved.

Epoxy Resins

A thermosetting resin based on the reactivity of the epoxide goup. One type is made from epichlorhydrin and bisphenol A. Aliphatic polyols such as glycerol may be used instead of aromatic bisphenol A. Molecules of the type have glycidyl ether structure, --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. Hydrogenated bisphenols can be used to add flame-retardant properties. The reactive epoxies form a tight cross-linked polymer network and are characterized by toughness and good adhesion, corrosion resistance, chemical resistance, and dielectric properties.

Polyvinyl Alcohol

A type of thermoplastic, polyvinyl acetate is a rubbery synthetic polymer with the structure (C4H6O2)N

Isononyl alcohol

AKA iso-nonanol, is predominantly used as an alcohol component in plasticizer manufacturing.

Water-based

Added to a formula to increase viscosity.

Plasticizers

Added to a stabilized elastomer or blend to obtain the balance of properties required to meet design requirements. A good plasticizer should be incompatible with the elastomer and thus have little or no effect on the glass-transition temperature (Tg) of the adhesive. It is intended to increase the overall softness, by may also increase apparent tack by providing greater deformability.

Impact modifiers

Added to improve toughness in a formulation.

Liquefiers

Additive used to turn a solid or a gas into a liquid state.

Humectants

Agents that have a pronounced effect on the ability of moisture to adhere to a substance. Sometimes used in anti-static coatings for plastics.

Carboxymethyl Cellulose

An acid derivative of cellulose whose sodium salt is used in manufacturing as a stabilizing and emulsifying agent. Cellulose derivative formed by its reaction with alkali and chloroacetic acid. CMC dissolves rapidly in cold water and is mainly used for controlling viscosity without gelling. as its viscosity drops during heating, it may be used to improve the volume yield during baking by encouraging gas bubble formation. Its control of viscosity allows its use as a thickener, phase and emulsion stabilizer (ie with milk casein), and as a suspending agent.

Defoamers

An additive that, when added to a liquid, breaks foam. This is in contrast to anti-foam, which prevents foam formation.

Epoxidized

An additive used as a plasticizer in plastic materials, especially PVC and its copolymers.

MICA

Any group of chemically and physically related aluminum silicate minerals.

Elastomers

Any of various polymers having the elastic properties of natural rubber.

Introduction to Fillers

Any solid powdered material that would be added in bulk to an adhesive is a filler.

Polyethylene/EVA Copolymers

EVA's are random copolymers of ethylene and vinyl acetate. Polymers with up to 16% vinyl acetate are used widely in packaging, particularly as adhesive tie-layers in multiwall packages. Polymers with vinyl acetate content above 18% are the most common resins used in hot-melt adhesives. In adhesives, EVA is essential in creating a variable-temperature-activated adhesive that provides flexibility at low temperatures and sufficient open time and hot tack at high temperatures. The combination of various EVA grades allows customization of products without changing the overall EVA-copolymer content. In sealants, EVA allows for high mineral content, better processability in compounds and the ability to be expanded with chemical blowing agents.

Sodium silicates

Can be used as a cost-effective extender for adhesive and sealant formulations. It is a clear, colorless liquid with a viscosity of 42*Baume.

Talc

Can be used as an extender in adhesive and sealant formulations. Talc is frequently added to reduce the manufacturing cost of the formulated adhesive.

Fatty Acids

Carboxylic acid with a long unbranched aliphatic tail, which is either saturated or unsaturated.

Pigment Dispersions

Certain pigments are affected by heat (when they will change color, and so a check is necessary on the heat stability of the colors chosen relative to the manufacturing process and end use. Pigments can contain a metal, which might deteriorate the elastomer used, calling either for the use for a chelating agent or the selection of an alternate pigment. Dispersing a pigment directly into an adhesive can be difficult, and is better performed either by pre-dispersing the pigment is a suitable carrier with the use of a commercial dispersing agent or by using commercially pre-dispersed pigment system.

Nitroparaffins

Characterized by a nitro group (NO2) attached to a one-two or three-member carbon chain. Some of the nitroparaffins functions include agricultural and pharmaceutical intermediates, specialty solvents for coatings or industrial processes, and fuel and fuel additives.

Persulfates

Chemical compounds that contain either the peroxomonosulfate (or peroxymonosulfate) ion, or the peroxodisulfate (or peroxydisulfate) ion. Persulfates are used in the preparation of adhesive films and metal bonding adhesives.

Dispersing Agents

Chemical compounds that, when added to a colloidal suspension, tend to make the particles more disperse.

Dithiocarbamates

Chemical used as an accelerating and vulcanizing agent.

Stabilizers

Chemicals added to a formulation to inhibit reactions between two or more chemicals.

Diethylene Glycol Dibenzoate

Clear, colorless to slightly straw colored liquid with faint aromatic odor and is slightly soluble in water. Produced from benzoic acids, and belongs to the glycol benzoate ester group, which is chemically stable and has high boiling point diesters. DGD is very soluble in defferent polymers, and is used as a plasticizer in Polyvinyl acetates (PCAc) and PVC coatings, in floor coverings, and plastisols (roof coatings). Other applications include as a platicizer in glue, caulks, sealants and paints. It is approved by the FDA for use in plastic and glues for food packaging.

Driers

Compound that catalyzes or accelerates the drying (curing) of a paint or adhesive, or the cross-linking of polymers or drying oils. Driers are not the same as curing agents, which chemically react with the polymeric material.

Antioxidants

Compounds that inhibit chemical reactions with oxygen. Oxidation reaction may involve highly reactive molecules called free radicals. Free radicals are molecules that have lost an electron and try to replace it by reacting with other molecules. This causes the substance to break down. Metals often catalyze reactions with oxygen. Antioxidants inhibit these changes by reacting with the free radicals before they can react with oxygen (free radical scavenging or by reacting with the metals.

UV-Curing Resins

Comprised of acrylate and methacrylate monomers and oligomers. They are formulated with photoinitiators (chemicals that decompose with the energy from UV or visible light) and cure by free-radical-initiated polymerization. Newer systems involve monomers like cycloaliphatic epoxies and vinyl ehters, which cure by a cationic mechanism initiated by stong acids generated from the UV decomposition of novel ionic salts. UV systems are very valuable as very-fast-curing coatings, adhesives, sealants and gasketing compounds in a range of industries.

Block polymers

Comprised of blocks of differ polymerized monomers, block copolymers are used in heat activate or pressure sensitive adhesives.

Crosslinking and Curing Agents

Crosslinking improves three basic properties of the adhesive: it provides a higher temperature resistance, it provides improved shear resistance and it increases solvent resistance. All of these stem from the same cause- reduction of mobility of the polymer. An added benefit to crosslinking, which is not readily apparent, is that the product is less prone to oxidation, which increases working life. The degree of crosslinking can be manipulated by the quantity of crosslinking agent used. A crosslinked polymer is often referred to as "having been cured."

Dipropylene Glycol Dibenzoate

DPGDB has a number of specialized applications. It is used as a plasticizing agent in polymers, particularly in the packaging industry for carton sealing, book binding and labeling purposes. It also finds uses in paste dispersions and cosmetics.

Styrene Butadiene Rubber

Derived from the random copolymerization of styrene and butadiene. Two predominant technologies currently prevail. Solution S"BR is polymerized in a hydrocarbon medium. Emulsion SBR polymerization takes place in an aqueous medium and soap as an ingredient in the coagulation process.

Polymers

Describes long chain natural and synthetic molecules, and describes materials that are commonly called plastics, rubbers, and resins.

Styrene Resins

Describes materials like acrylonitile butadiene styrene (ABS)

Urethane Resins

Describes polyurethane polymers used in the adhesives, sealants, coatings, and elastomers markets. Urethane resins can be supplied as polyurethane prepolymers, fully reacted thermoplastic polyurethane polymers or waterborne polyurethane dispersions. for adhesive applications, polyurethane prepolymers can be moisture cured or cured by combination with a second component containing hydroxyl or amine groups. Fully reacted thermoplastic polyurethane polymers and waterborne polyurethane dispersions are typically heat-activated and bonded with pressure.

Water-Treatment Chemicals

Eliminate impurities used is feed water for process applications. They are also used to control corrosion and other damage to water-tube boilers, heat ex-changers, cooling towers and chillers. Water-treatment chemicals include ion exchange systems, chemical softening systems, de-mineralizers and other chemical-control systems.

Epoxy Curing Agents

Epoxies can be formulated as one-component or two-component systems. One-component systems are heat-cured and usually use dicyandiamide (DiCy) as a curing agent. Two-component epoxies are more common, and a range of curing agents is available. The cure kinetics and the glass-transition temperature (Tg) of the cured resin are dependent on the molecular structure of the curing agent. Curing agents include aliphatic amines, amidoamines, aromatic amines, cycloaliphatic amines, imidazoles, polyamides, anhydrides, polysulfides, and boron trifluoride adducts.

Ester

Epoxy ester resins are based on epoxy resins that have been esterified with a fatty acid. Epoxy esters generally dry or cure by reaction with oxygen, similar to alkyl resins. Epoxy esters offer higher performance than alkyl resins with the ease of handling a one-component system.

Polychloroprene

Especially resistant to oil. It was the first synthetic elsastomer, or rubber, to be a hit commercially. Invented by Arnold Colling while working under the same fellow who invented nylon, Wallace Carothers

Carbon Black

Essentially synthetic soot produced by the incomplete combustion of natural gas. Its major use is as a reinforcing filler and pigment for rubber compounds, the largest application being in tires.

Polyolefins

Most important plastics used worldwide and comprise polymers and copolymers of olefins, such as ethylene, propylene, butane, and hexene. The polymers range from rigid plastics like polypropylene and high-density polyethylene to soft, rubbery materials called plastomers, which are intermediates between plastics and rubbers. The so-called thermoplastic olefins (TPO) are blends of polyolefins like polypropylene with rubbers such as ethylene propylene dienemonomer (EPDM) and are very widely used as plastic films in automotive interiors.

Phosphite

Phosphite antioxidants are high-performance solid antioxidants. They offer processing stability, color stability and protection porperties for thermoplastic polymers(polypropylene, high-density polyethylene, low-density polyethylene, polycarbonate,etc). They produce excellent effects when used with phenolic antioxidants and contribute significantly in achieving color stability during compounding.

Inorganic Pigment Dispersions

Pigment dispersions that comprise inorganic pigments.

Polybutadienes

Polybutadiene rubber was first manufactured in Russia and Germany in the 1920's by polymerizing butadiene with sodium. This was called "Buna" rubber. Today most polybutadiene is produce in solution with alkyl lithium catalysts and is used in tire production. Latices of polybutadiene are still manufactured and used in adhesives. Polybutadiene is a very tacky polymer with a very low glass-transition temperature (Tg) of -79*C. Latices are used for manufacturing low-temperature pressure-sensitive adhesives for tapes and labels. They are also used as heat-curable adhesives/sealants in the automotive industry.

Polyester Resins

Polyesters are formed from the reaction of a di-acid and a glycol, and are available as saturated or unsaturated polyesters. Saturated polyesters include common thermoplastics such as polyethylene terphthalate (PET), and are frequently used as thickeners and and performance improvers in adhesives and sealants. Unsaturated polyesters, usually diluted with styrene, are crosslinked with peroxide initiators and are used to make chemically resistant tanks and piping, countertops, and sanitaryware, plus a range of materials like automotive body fillers and impregnation/coating resins for metals and electrical items.

Sorbitol

Polyhydric alcohol used as a component of alkyd-type resins.

Polymer Emulsion

Polymer emulsions of acrylics are the most versatile of the synthetic emulsions (or latex) polymers. Acrylic emulsions are the fastest-growing category of adhesives emulsions and are low-cost alternatives to polyurethanes in many flexible-packaging applications. They are also one of the leading technologies for producing high-performance pressure-sensitive adhesives and high-performance sealants.

Flame and Smoke Retardants

Polymers initiate or propagate fires bc they decompose to volatile, combustible products when they are exposed to heat. However, in many fields, the use of polymers is restricted by their flammability, whatever the importance of the advantages their use may bring. The present diffusion of synthetic polymers has greatly increased the "fire risk" and the "fire hazard," that is, respectively, the probability of fire occurrence and its consequence either to humans or to structures. To fulfill these requirements, flame retardants need to be added into the polymer. The role of these additives is to slow down polymer combustion and degradation (fire extinctions), reduce smoke emission and avoid dripping.

Pure monomer resins

Polymers or copolymers of varying ratios manufactured from pure monomers, such as styrene.

Organic Pigment Dispersions

Popular in various industries. They can prove to be a clean and cost-effective way of coloring many products. The basic idea is to take an organic/inorganic pigment and disperse it into a liquid solution made up of a resin (or surfactant) and solvent (or water/oil/other carrier). The process involves a pre-mix (all the ingredients mixed together using a high-speed mixer) being passed through a bead mill ( a horizontal or vertical chamber filled with tiny beads being agitated) until the required level of dispersion is achieved. The amount of dispersion required will also depend on the ingredients being used and the end application.

Acrylic Resins

Prepared by polymerizeing acrylate and methacrylate resins. A range of homopolymers and copolymers is available, ranging from simple plastics like polymethyl methacrylate to complex coploymers 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 applicaions, including packaging, carpet manufacture, and construction. The sold resins can also be used as inert thickeners in adhesives like cyanoacrylates and anaerobics.

Hexamine

Prepared by the reaction of formaldehyde and ammonia, which yields crystalline hexamine. Hexamine is used as a crosslinking agent for hardening phenol formaldehyde resins and for vulcanizing rubber.

Aliphatic Hydrocarbon Resins

Primarily in hot-melt adhesives, coatings and pressure-sensitive adhesives.

Softeners and Anti-blocking Agents: Hydrogenated Castor Oil

Produced when castor oil is hydrogenated with nickel catalyst. Its white flakes are extremely insoluble and are water resistant.

Glycerine

Products composed primarily of glycerol. Clear, almost colorless liquid with a molecular weight of 92.09

Protein-Based

Protein resins used in structural adhesives come from several sources, such as animal blood, fish, milk, connective tissue and soybeans. Protein-based adhesives have been used throughout history Their primary use in modern times is in the production of plywood for interior applications.

Silica, Quartz and Diatomaceous

Quartz silica is a colorless, white, variable, black, purple, or green crystal. It is odorless and will not burn. A form of hydrous silica, diatomaceous silica is processed from natural diatomate, a sedimentary rock of varying degrees of consolidation that is composed essentially of the fossilized siliceous skeletal remains of single-cell aquatic plant organisms called diatoms. It consists of 83-89% silica, and its many uses include fillers for plastics. Known as diatomaceous earth, it has a particle size of 6-10 micrometers.

Polyvinyl alcohol

Used as very important additives or modifiers in polyvinyl acetate emulsion-based adhesives, or as the major component in solid fiber laminating and spiral-tube winding adhesives. Polyvinyl alcohol adheres particularly well to cellulosic substrates such as paper and wood. Adding it to a polyvinyl acetate emulsion will increase the efficiency as well as the tensile strength of the resulting adhesive.

Plasticizer alcohol

Used for the production of a PVC plasticizer, which transforms PVC, a naturally brittle plastic, into a flexible material.

Mineral Oil

Used in hot-melt and pressure-sensitive adhesives manufacturing to adjust properties such as viscosity and hardness.

Anti-Foaming Agents

Used in water-based systems to minimize the generation of foam, particularly during high-shear mixing operations. Anti-foams are usually immiscible with water, and very small amounts are usually very effective. De-foamers are additives that, when added to a liquid, break foam.

Vulcanizing Agents

Used to crosslink rubber compounds. The most commonly used material is elemental sulfur, although peroxides are used with some elastomer types.

Polyols

Used to describe a short-chain molecule or polymer with two or more alcohol groups. Polyols can comprise hydrocarbon backbones with alcohol functionality, but the two most common types are polyester and polyether polyols. These are used as precursors to acrylic monomers and are used widely in the manufacture of polyurethanes.

Phthalates

Used to manufacture viscosity control agents, gelling agents, film formers, stabilizers, dispersants, lubricants, binders, emulsifying agents, and suspending agents for end used applications in adhesives, glue, coatings, printing inks, and more.

Azelaic acid

Used to prepare esters that are excellent low-temperature plasticizers for polyvinyl choride (PVC). the most common plasticizer is di-2-ethylhexyl azelate, known generically as DOZ

Accelerating Agents

Used to speed up the vulcanization process and improve the properties of the vulcanized material. Ex: amine-aldehydes, thiazoles, guanidines, sulfenamides, dithiocarbamates and xanthates.

Non-Silicone

Typically based on polyalkylene/polyethylene glycols and refined hydrocarbon oils.

Sodium, Potassium and ammonium alginates/ polyacrylates

'Algin'~alginic acid, alginates (salts of alginic acid) and PGAs (alginate propylene glycol esters). Alginates were first isolated from seaweeds over a century ago an have been in commercial use for the better part of a century. Consequently, they are one of the most well established hydrocolloids in the market today. All hydrocolloids have two basic functions: they either thicken or gel water. Their ability to do this gives rise to many useful properties- viscosity control; stabilization of suspensions, emulsions and foams; improved freeze/thaw stability; film formation; rheology control; and more. Alginic acid, an intermediate in the alginate manufacturing process and also a line product, is insoluble in water. However, when added to water it swells. Alginates, the water-soluble forms of the product, are made by neutralizing alginic acid to give the appropriate soluble-salt forms, most notably the sodium, potassium, and ammonium salts. These so-called monovalent salts are the water-soluble forms of algin that are most commonly used as thickeners.

Vinyl Resins

(CH2==CH--), specifically vinyl chloride, vinyl acetate and simlar esters, but also referring more generally to other types of compounds. Polyvinyl chloride (PVC) is a hard, rigid polymer that can be plasticized to make a soft, flexible version. PVC is the second-larges-volume polymer produced in the world (after polyethylene), and its main application areas are in construction (Ie, vinyl siding), furniture, and packaging. The vinyl compounds are highly reactive and polymerize easily.

Caustics and Caustic Soda

(NaOH) is a base material used in the manufacture of pulp and paper, detergents, foodstuffs, textiles, and more.

Perchloroethylene

(PERC) is a colorless, nonflammable liquid. It can be added to aerosol formulations, solvent soaps, printing inks, adhesives, sealants, polishes, lubricants, and silicones.

Sebacates

Esters produced from 2-ethylhexanol and higher alcohols with linear aliphatic acids that are used in demanding flexible PVC applications where superior low-temperature performance is required. They give superior low-temperature performance to adipates, but also command a significant premium, and their usage is generally limited to extremely demanding low-temperature flexibility solutions.

Vinyl Acetate Ethylene Emulsions

Ethylene vinyl acetate copolymers (EVA) are conventionally regarded as those copolymers of ethylene and vinyl acetate where the weight percentage of ethylene in the polymer molecule exceeds that of the vinyl acetate. Adhesive grades generally fall in the range of 14% to 35% vinyl acetate and have a melt index (a measure of tendency to flow at elevated temperature) in the range of 5-2,500. The vinyl acetate content and the molecular-weight range influence adhesive properties and hot-melt rheology. The higher the ethylene content, the better the specific adhesion to non-polar substrates, such as polyolefins. The polymers higher in vinyl acetate show improved adhesion to polar substrates such as paper. Lower-molecular weight polymers yield lower-melt-viscosity hot melts that are easier to process and apply. These also provide better wetting and, thus, improved mechanical adhesion to porous substrates, such as paper and wood. Higher-molecular-weight polymers are used for applications requiring optimum cohesive strength at elevated temperatures and good low-temperature flexibility.

Rheology Modifiers (Viscosity- and flow-control agents)

Every adhesive and sealant has to have the correct flow properties to work in its targeted application. These flow properties are the result of the rheology of the material. This is true of such diverse materials as spray-applied adhesives ad caulks. Rheological modifiers are used to control how the product will respond to a variety of shear conditions. For example, a caulk must thin out as it passes through the nozzles of the applicator, but it must regain its viscosity quickly so that it forms the proper bead. Spray applied adhesives must also thin out during application, but they need to recover their viscosity more slowly to allow for the proper flow-out on the substrate.

Citric Acid Esters

Exhibit a low order of toxicity and provide superior processing properties with PVC and other prevalent polymers.

Foaming Agents

Facilitates foam formation (ie, surfactant)

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.

Castor Oil (polymerized/Oxidized)

Frequently used as a plasticizer for inks, lacquers and adhesives.

Hydrocarbon Resins

Generally made from petroleum-based feedstocks, either aliphatic (C-5) or aromatic (C9), or dicyclopentadiene (DCPD), or mistures of these. the monomers are polymerized using catalysts such as AlCl3 or BF3, or in the case of DCPD, thermal polymerization can be employed. These resins can be sold as is or after they have been dydrogentated to reduce either color or levels of unsaturation.

Pine Oil

Generated by the steam distillation of needles, twigs and cones from a variety of species of pine trees.

Solid Hydrocarbon resins

Typically found in pastille or flake form

Silica

Ground silica performs as a functional extender to add durability and anti-corrosion and weathering properties to epoxy-based compounds, sealants, and caulks.

Natural Latex

Harvested from the tree Hevea Brasiliensis, a tree native to South America that is harvested on rubber plantations in Southeast Asia. The latex can be used in the latex form or coagulated as so-called, "natural rubber." The latex finds many uses, including adhesives and foam manufacture. Disposable medical gloves have provided a major growth area in recent years, but concerns have arisen due to severe latex allergies in some users caused by residual proteins found in the gloves.

Phosphates

Impart flame-resistant properties to adhesives, sealants, and plastics.

Coalescing Agents

Improve the curing or film formation of a resin and are specific to the resin chosen. Very slow evaporating solvents are commonly used because the coalescing solvent must remain in the voids between the resin particles during the early stages of evaporation, and still be in the film during the late stages so it forms evenly and doesn't clump. After the film formation is complete, the coalescing solvent evaporates altogether.

Thickening agents

Increases viscosity

Anticorrosive Pigments

Inhibit or prevent metal corrosion

Drying salts

Inorganic agent that readily takes up water to become hydrated. Several such salts are commonly used as drying agents: CaCl2, CaSO4, MgSO4, K2CO3, and NaSO4. Of these salts, magnesium sulfate is a fine powder and the rest are of a larger particle size.

Kaolin and Clays

Kaolin (aka China clay) is a pure form of hydrated aluminum silicate clay and is best known as the precursor of porcelain. Various forms of this mineral are found in many parts of the world. When used as a filler in adhesives, sealants, rubbers, or coatings, its hydrophobic nature leads to a lowering of moisture absorption and an increase in dielectric strength.

Aluminum Silicate

Kaolin, often called China clay, is a pure form of hydrated aluminum silicate clay and is best known as the precursor of porcelain. When used as a filler in rubbers, coatings, sealants, or adhesives, its hydrophobic nature leads to a lowering of moisture absorption and an increase in dielectic strength.

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 ration, increased moisture resistance, greater water repellent properties, improved adhesion and better flexibilization.

Resin Intermediates

Low- molecular-weight materials with a silanol or methoxy functionality.

Butyl Rubber

Mainly polyisobutylene, but with ~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 ~350-450,000. 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 UV 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.

Inorganic pigments

Mainly useful where high opacity is needed. They can also protect against heat, light and weather, and offer light and ink stability. These pigments include carbonates, sulfides, silicates, chromates, metallic oxides, sulfates, ferrocyanides and carbon. Basically, they can be broken down into two categories: white and colored iron oxides.

Palmitic Acid

Major component of the oil from palm trees. As a defoamer, it can reduce and mitigate the formation of foam.

Phenolic

Many antioxidants are phenolic compounds. Phenolic antioxidants are excellent hydrogen donors and are widely used to stabilize polymers.

Corrosion Inhibitors

Material that provides physical protection against corrosive attack or reduces the open-circuit potential difference between local anodes and cathodes. EX: hexamine, phenylenediamine, dimethylethanolamine, sodium nitrite, and others.

Additives

Material used to change, or prevent or minimize changes in properties in a formulation.

Emulsifying Agents

Materials added to an emulsion to prevent the coalescence of the globules of the dispersed phase.

Hydrogenated Hydrocarbon Resins

Materials used as tackifiers in hot-melt and pressure-sensitive adhesives.

Thixotropes

Materials used to modify adhesive rheology

Melamine and Melamine-type Resins

Melamine is widely used in wood-panel glue systems. Melamine urea formaldehyde resins are used in the production of particleboard, plywood, oriented-strand board and fiberboard where the resin is part of the binding system used to form the panel. The panels derive their improved durability, low formaldehyde emissions and moisture resistance from the melamine resins.

Latex resins

Milky, aqueous dispersion of a natural or synthetic rubber or resin. This term is also frequently applied to synthetic emulsion polymers.

Natural Rubber

Most useful elastomer for pressure-sensitive adhesives, consisting largely of cis-polyisoprene. With a broad molecular weight, ranging ~500,000-2,000,000, there is much that can be done with natural rubber. There is a twin spread of molecular-weight distribution in natural rubber, and the higher fraction contributes considerably to shear resistance. Natural rubber is very compatible with many raw materials and offers a good balance of properties when used in a PSA. Is is soluble in a variety of aliphatic and aromatic hydrocarbons and chlorinated hydrocarbons, but is insoluble in ketones and alcohols. It is forgiving in that the ratio of natural rubber to tackifier used in formulations is usually non-critical: it takes a change of around 5% before any noticeable change in properties occurs. There is a reasonable quantity of protein present that acts as a natural preservative. It is available in a wide range of grades.

Microspheres

Multi-functional additive for use in adhesives and sealants. The heat-activated unexpanded form is used in heat-cured materials as a foaming or expanding agent. When used in the pre-expanded form, microspheres are an ultra low-density, compressible hollow particle. They are used to reduce shrink and drying time, cut cost, increase compressibility and resilience, and lower the weight of materials.

Bentonites

Naturally occurring material used to thicken adhesive and sealant formulations.

Benzoates

Obtained by trans-esterification of methyl benzoate with the corresponding diol (glycol-, dithylenglycol-, and triethyleneglycol esters)

Casein

Obtained from milk by precipitation induced by acids such as lactic acid. Milk-based adhesives are called casein-based adhesives.

Benzoic Acid

Occurs naturally in a variety of products but is also industrially synthesized. Benzoic acid is used in the manufacture of plasticizers, resin coatings and caprolactam. It is an antiseptic, anti-fungal and anti-pyretic agent, and can be used as an alkali-metric standard.

Guar gums

Off-white powder that can bind solids and water through hydrogen bonding; control the viscosity of aqueous solutions; and form strong, tough films.

Liquid Hydroxyl-terminated Polybutadienes

Offer good transparence, low viscosity, age resistance, low temperature performance, and good process capability.

PVC

One material used as both a surfactant and part of a colloid protection system is hydrolyzed polyvinyl acetate (PVAc). The material is either polyvinyl alcohol (PVA) or PVA-co_PVAc. These combinations of surfactants and cellulosic protective colloids optimize properties, provide improved wettability on various surfaces, or have the potential for crosslinking.

Waxes

One of the most important ingredients in a hot-melt adhesive formulation is the wax. Waxes decrease the viscosity of the melt and the surface tension of the liquid adhesive. As hydrocarbon-type materials, waxes, in general, have a lower surface tension than the base polymer of the hot melt, and thus lower the surface tension of the overall adhesive. Certain waxes, known as micro-crystalline waxes, not only reduce melt viscosity and melt surface tension but they also reinforce the hot melt by forming crystallites that resist deformation under load.

Urea

Organic compound (aka carbamide) used in various adhesives (ie, urea-formaldehyde or the urea-melamine-formaldehyde used in marine plywood).

Polyvinyl Alcohols

PVAs are used as very important additives or modifiers in polyvinyl acetate emulsion-based adhesives, or as the major component in solid-fiber laminating and spiral tube winding adhesives. Polyvinyl alcohol adheres particularly well to cellulosic substrates such as paper and wood. Adding it to polyvinyl acetate emulsion will increase the efficiency as well as the tensile strength of the resulting adhesive.

Reasons for adding filler:

Reduces overall cost (ie clay or CaCO3); creates an opaque adhesive (ie masking tape~titanium oxide); gives color with pigments [which tend to contain metal (which might deteriorate the elastomer used)] or dyes (which tend to migrate/bleed); to reinforce, which will improve holding power and possibly adhesion (ie zinc oxide) as well as reducing tendency to cold flow; to dry a too-tacky adhesive system (ie starch, talc and colloidal silica); to provide flame retardance (ie antimony oxide); to provide artificial thickening by thixotropy (ie colloidal silicon dioxide);to provide electrical conductivity (ie carbon black, aluminum, or silver particles); to aid in a chemical reaction (ie zinc oxide supporting a phenolic cure)

Rosins

Resins extracted from several types of pine trees. They can be distilled to remove volatiles like turpentine and polymerized to form a range of resins and oils, which are useful as base materials and tackifiers in solvent-based and hot-melt adhesives, sealants, and coatings.

Maleic Resins

Resins produced from maleic anhydride monomer, such as styrene maleic anhydride copolymer, an alternating copolymer of styrene and maleic anhydride that is produced by the free-radical polymerization of the mixed comonomers.

High-solids Resins

Resins with a high solids content.

Pentaerythritol esters

Rosin esters used to aid adhesion in a formulation

Stearic Acid

Saturated fatty acid with an 18 carbon chain, waxy solid.

Silicone

Silicone anti-foams are typically formulations of dimethylpolysiloxane fluids and silica. They are chemically inert and insoluble in most foaming systems. This enables them to retain their activity over a long period of time.

Silicone dispersions

Silicones are polymeric materials that have alternating silicon and oxygen atoms in their backbone. They are available in various molecular weights and forms. Emulsions or dispersions in water are used as lubricants and defoamers. Crosslinked polymers are formed using two-component systems that cure with atmospheric moisture. These polymers are high-performance elastomers with very high flexibility and outstanding high-temperature performance. Very highly crosslinked systems are more rigid and are known as silicone resins. The resins are used in high-temperature electrical applications.

Monomers

Single unit molecule used to make polymers, many of which are sued in the adhesives industry (ie, ethylene is polymerized to polyethylene).

Solid acrylic resins

Solid acrylic resins are comprised completely of sold content. They can be used as inert thickeners in adhesives like cyanoacrlates and anaerobics

Dispersions

Solid finely dispersed in a liquid. In contrast to solutions, dispersions are heterogeneous on a microscopic scale. Colloid chemist 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.

E Solvents

Solvents are used in the manufacture of solvent-borne pressure-sensitive or contact adhesives. Can also be used to remove adhesive residue or to soften an adhesive to facilitate removal.

Tackifiers

Specialty resins used in formulation of adhesives and sealants to add "tack" and improve adhesion. They may be hydrocarbon resins, rosin esters, phenolic resins, coumarone-indene resins or terpene phenol resins, depending on the raw material. Tackifiers provide increased tack and adhesion by creating a physical bond with the surface material, which may be paper or an elastomer. They also deliver other performance advantages, such as improved hardness and reduced viscosity. Low molecular weight tackifiers, in particular, enable formulators to achieve low-viscosity formulations. This improves compatibility with the system, making it easier and faster to incorporate all materials, including fillers and plasticizers. Tackifying resins enhance a broad range of adhesives and sealants, from hot-melts to packaging adhesives. Depending on the level of tack required for the specific application, various levels of adhesion can be achieved simply by modifying system components. In general, the tackifier may account for up to 80-90% of a typical adhesive or sealant formulation.

Anti-Skinning Agents

Substance added to a material to prevent or retard the processes of oxidation or polymerization, which result in the formation of an insoluble skin on the surface of the material.

Wet-state

Substance added to protect, prevent, or retard day, discoloration, or spoilage during use or storage.

Wetting Agents

Substance used to reduce surface tension, thereby facilitating spreading or impregnation of a surface. Media that dry out commonly fail to re-wet properly for a number of reasons. Waxes, resins, organic acids and other chemicals present in organic-media components are inherently water-repellent. Water repellency (hydrophobicity) is a condition that prevents water from adhering to and moving uniformly into and through a medium. The reason media do not wet consistently is that the particle surfaces and pores within these media are constantly changing every time they undergo we-to-dry cycles. A wetting agent imparts a "film" to all of the particle surfaces within the medium and allows the medium to retain its ability to uniformly wet-out for several days to several weeks.

Detergents

Surfactants or mixtures of surfactants that offer cleaning properties in dilute solutions.

Fluoropolymers

Synthestic carbon-based resins used in the manufacture of high-performance industrial coatings.

Polyisobutylene

Synthetic rubber, or elastomer. It is the only rubber that is gas impermeable; that is, it is the only rubber which can hold air for long periods of time.

Trimellitic anhydride

TMA is a chemical used in the manufacture of coatings, epoxy curing agents, printing inks and vinyl plasticizers.

Colloidal Stabilizers

The adsorption of homopolymers and block copolymers at sold-liquid interfaces is crucial for controlling the colloidal stability and, hence, the rheology of concentrated suspensions used in many applications, including adhesives, ceramics for electronic and structural purposes, paint, pharmaceutical products, and paper coatings. Block copolymers that form self-assembled brush layers have proven to be particularly effective colloidal stabilizers.

Preservatives

The microbial contamination of adhesives and sealants can cause undesirable effects such as odor, discoloration, loss of stability or viscosity, changes in pH, and gas generation. Consequently, the contaminated products are unusable and unsatisfactory to customers, and the recovery operations costly and time consuming. Microbial contamination can occur during manufacture and/or storage of finished products prior to use by the consumer; this is known as in-can contamination. Alternatively, once the adhesive or sealant is applied, fungi and yeasts can colonize the surface film, causing discoloration and degradation; this is known as dry-film contamination. Antimicrobial agents provide both fungicidal and bactericidal activity, making them ideal for use as in-can preservatives for a range of adhesives and silicone emulsions.

Sodium Benzoate

The sodium salt of benzoic acid, sodium benzoate, fulfills an antibacterial and anti-fungal role.

Polyamino Co-reactant

These resins are solvent-free, amine-functional reactive partners for polyisocyantates.

Zinc Oxide

This fine-particle-size mineral is a white powder widely used as a pigment and accelerator. It is an excellent UV absorber and valued as an additive for outdoor applications.

Zinc Oxides

This fine-particle-size mineral is a white powder widely used as a pigment and accelerator. It is an excellent UV absorber and valued as an additive for outdoor applications.

Phenolic resins

Type of synthetic thermosetting resin invented by Leo Baekeland, PhD(1907). AKA Bakelite. The resins are used in the production of molded products such as billiard balls and laboratory counter-tops, and as adhesives and coatings.

Adhesion promoters

Usually acid-modified or hydroxyl monomers. Their dual functionality helps formulators increase adhesion and lower viscosity. Depending on the application, polyester oligomers and specialty resins may also function as adhesion promoters. AP crosslink on the surface, which may be glass plastic or another substrate. The surface material plays a critical role in product selection because different materials require specific APs in order to achieve optimal results. APs reactive sites must be adaptable to reacting with the surface material. Dual functionality monomers are often used as APs for this reason bc they help activate many surface materials and make them more responsive. Additionally, acid esters are often used bc they provide a proton or neutron that can be linked on the surface. Commonly found in laminating adhesives.

Extender pigments

Usually chemically inert compounds that can be found naturally or made synthetically. Extenders provide characteristics to pigments such as thickness, gloss and durability.

Extenders and Fillers

Usually relatively inert natural or synthetic substances such as chalk, talc, clay or calcium carbonate. Extenders and fillers generally can be classified in to two categories. The first is to reduce the quantity of the more expensive functional components in an adhesive or sealant. These extend the effectiveness of the functional components and may also fill open space in the structure of the adhesive/sealant system.In either case, the extender-filler does not interfere with the function of the other components. The second category is functional extenders and fillers, which contribute to the overall performance of the product in which they are used. These occupy space and extend the basic adhesive/sealant system, but also improve physical properties, particularly hardness, stiffness, and impact strength, as well as provide improved processing, density control, optical effects, thermal conductivity, control of thermal expansion, electrical properties, magnetic properties, and flame retardancy. Fillers differ from reinforcing agents in that they are small particles and do not markedly improve the tensile strength of the base material.

Nitromethane

Volatile liquid that is added in small amounts to many halogenated solvents and aerosol propellants as a stabilizer. It is also used as a polar solvent for certain polymers and resins.

Silane

When added to adhesives, silanes can provide improvement in adhesion by reducing moisture attack at the interface. This results in improved moisture, temperature and chemical resistance.

Titanium Dioxide

White pigment and filler produced mainly from ilmenite (iron titanate) and natural rutile (titanium dioxide). It is widely used in adhesives, paints, paper, plastics, ceramics, rubber, inks and a variety of other products.

Sodium Fluorides

White, crystalline, water-soluble powder used in a variety of industrial applications.

Calcium Carbonate

Widely used due to low cost, availability, low oil absorption and high brightness. It is also non-abrasive to processing equipment. Finer grades, including precipitated, are recommended in high-gloss applications, while coarser grades are used for gloss control in matte and low-gloss products.

Choosing a Resin

With so many resins available, how does one choose the right one for a particular application? Basic criteria narrow down the choice, and then a number of secondary filters are applied. Resin suppliers really sell two basic properties: compatibility and stability. In most formulations, especially adhesives, the polymer is the starting point of the mixture, which means that the resin must have a known and understood compatibility with the polymer and with other ingredients. Viscosity, color, and oxidative stability are very important criteria if not understood, can affect application and end used properties, resulting in blocked nozzles, poor coatings, and failed or discolored adhesives. Stability is proportional to cost, so choices are made around what stability is really required for the adhesive. With basic criteria of compatibility and stability in place, secondary filters come into play: FDA clearances; odor; color; cost. New resins are often developed as a response to market and polymer changes. Trends such as biodegradability and re-pulpability will result in new polymers with a different structure that will require different resins and other additives. Advances in radiation-curing techniques will also result in new polymers and resins with the required ability to add adhesion and modify rheology without impacting curing mechanisms.

Introduction to Resins

resin comes form resinous, the description of materials that are amorphous, brittle, and yet soft and tacky. Rosin from trees is the easiest example to relate to- gymnasts and baseball players use it for grip. Rosin derivatives form the oldest group of tackifier resins. The term resin is sometimes used to describe materials like PVC and acrylonitrile butadiene styrene (ABS) which do not fit the description used here for tackifier resins as follows: low molecular weight, less than 20,000 Mz, typically less than 5,000Mz; amorphous; melting points from liquid to 180*C; glass transition temperatures (Tg) from liquid to 130*C; colors from water white to brown. Resins are used to modify the bulk rheology and surface adhesion properties of a variety of polymers for many applications, including adhesives, paints, inks, was compounds, and chewing gum. In some cases, resins provide tackiness and an increase in specific adhesion, and in other cases they provide film forming and reduction in viscosity. When mixed with a polymer, a compatible resin will increase the Tg and reduce viscosity or hardness in contrast to a plasticizer, which generally will not modify Tg. There are many types of resins available from a range of suppliers. There are also a number of ways that they can be grouped. The most common way is by the feedstock used to producer them: hydrocarbon resins; rosin resins; terpene resins. Hydrocarbon resins are generally made from petroleum-based feedstocks, either aliphatic (C5) or aromatic (C9), or dicyclopentadiene (dcpd), or mixtures of these. The monomers are polymerized using catalysts such as AlCl3 or BF3, or in the case of dcpd, thermal polymerizatin can be empolyed. These resins can be sold as is or after they have been hydrogenated to reduce either color or levels of unsaturation. Rosin acids are derived from the root (wood resin) or sap (gum resin) or from the kraft process (tall oil rosin). Rosin acids can be tackifiers themselves, but is more common to use their ester derivatives. Terpene resins are derived from terpene feed-stocks, either from wood sources or from citrus fruit. AlCl3 also polymerizes these resins.