2022 Raw Materials, Chemicals, Polymers, and Additives Handbook

Additives and Chemical Specialties, F-Z

INTRODUCTION TO FILLERS

The term filler is a catchall for any solid powdered materials that would be added in bulk to an adhesive. The reasons for the addition can include the following:

• To reduce the overall cost of the adhesive, using fillers such as clay or calcium carbonate.

• To give color. The choice can be either pigments or dyes, but dyes have a tendency to migrate and also to bleed. 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 of 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 in a suitable carrier with the use of a commercial dispersing agent or by using commercially pre-dispersed pigment systems.

• To reinforce, which will improve the holding power, with a possible increase in adhesion, by use of additives such as zinc oxide or a silicate. The reinforcing action will also reduce any tendency to cold flow, as in a polyisobutylene adhesive system.

• To dry a too-tacky adhesive system, as is sometimes encountered, particularly induct tapes. Starch works well in this role, as do talc and colloidal silica.

• To provide artificial thickening by thixotropy, using an extremely fine particle-size filler such as colloidal silicon dioxide.

• To provide flame retardance, with an additive such as antimony oxide.

• To provide electrical conductivity. A suitable particle-size carbon black or aluminum or silver particles will do so.

• To aid in a chemical reaction, such as zinc oxide supporting a phenolic cure.

Extenders and Fillers

These are usually relatively inert natural or synthetic substances such as chalk, talc, clay or calcium carbonate. Extenders and fillers generally can be classified into 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.

Extenders and Fillers, Aramid Pulp

Heat-resistant synthetic aromatic polyamide materials.

Extenders and Fillers, Asphalts

Asphalts are highly viscous hydrocarbons produced during the commercial refining of crude oil or from natural sources and are used in sealants, primarily to impart water-resistant properties.

Extenders and Fillers, Calcium Carbonate

Calcium carbonate finds wide use due to its 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. (See also Extenders and Fillers.)

Extenders and Fillers, Carbon Black

Carbon black is 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. (See also Introduction to Fillers.)

Extenders and Fillers, Cellulose Fibers

Fibers obtained from the bark, wood, or leaves of plants, or from other plant-based material.

Extenders and Fillers, Cotton Fibers

Raw fibers from the cotton plant.

Extenders and Fillers, Coumarone Indene Resins

Any of a group of thermoplastic resins obtained by polymerizing mixtures of coumarone and indene.

Extenders and Fillers, Hydrocarbon Resins

Resins produced from petroleum-derived monomers.

Extenders and Fillers, Kaolin and Clays

Kaolin, often called 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. (See also Extender Pigments, Aluminum Silicate.)

Extenders and Fillers, Mica

Any of a group of chemically and physically related aluminum silicate minerals.

Extenders and Fillers, Microspheres

Thermoplastic microspheres are a multifunctional 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.

Extenders and Fillers, Polyester Fibers

Fiber made from ethylene glycol and terephthalic acid or its dimethyl ester.

Extenders and Fillers, Rosin Derivatives

A chemical substance made from rosin. Rosin derivatives form the oldest group of tackifier resins.

Extenders and Fillers, Silane

Silane is an inorganic compound with chemical formula SiH₄.

Extenders and Fillers, Silica

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

Extenders and Fillers, Sodium Silicates

Sodium silicate (Na₂SiO₃) 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.

Extenders and Fillers, Talc

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.

Extenders and Fillers, Terpene Resins

Terpenic resins, or polyterpenes, are the group of glass-like oligomers based on natural-product-sourced feedstocks such as alpha and beta pinene, di-pentene, di-limonene, and di-carene. These products originated from the polymerization of fractions of turpentine obtained from pine gum. More recently, the principal sources of feedstock have been turpentine, a byproduct of kraft paper pulping, and di-limonene, a byproduct of citrus juice production.

Extenders and Fillers, Wollastonite

A white or grayish mineral that typically occurs in tabular masses in metamorphosed limestone.

Flame and Smoke Retardants

In most cases, polymers initiate or propagate fires because, being organic compounds, 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 extinction), reduce smoke emission, and avoid dripping.

Foaming Agents

A material that facilitates formation of foam.

HUMECTANTS

Humectants are substances that promote the retention of moisture.

Humectants, Sorbitol

Sugar alcohol with high water solubility.

Humectants, Hexylene Glycol

Clear, colorless liquid that is fully miscible in water.

Impact Modifiers

Impact modifiers are added to improve toughness in a formulation.

Isocyanate Hardeners

Isocyanates are reacted with polyether or polyester polyols to form polyurethanes. The most commonly used isocyanates are aromatic, namely methylene diphenyl diisocyanate (MDI) and toluene diisocyanate (TDI). Isocyanates are also used as one-component binders to manufacture oriented-strand board (OSB), medium-density fiberboard (MDF), and particleboard, where they react with water to form urea linkages and bind together wood strands, fibers, and chips.

LIQUEFIERS

An additive used to turn a solid or gas into a liquid state.

Liquefiers, Thiourea

A white crystalline solid that is soluble in water.

Moisture Scavengers

In polyurethane adhesives, moisture scavengers are substances that remove humidity from compounds so they cannot generate any unwanted secondary reactions with isocyanates. In other adhesive systems, desiccants are used to absorb moisture from elastomeric systems, imparting excellent protection against porous substrates.

Moisture Scavengers, p-Toluene Sulfonyl Isocyanate (PTSI)

PTSI (para toluene sulfonyl isocyanate) is used in adhesives and coatings systems as a moisture scavenger. It chemically reacts with water to remove it from the system, which may cause detrimental effects. (See also Moisture Scavengers.)

Monomers

A single-unit molecule used to make polymers, many of which are used in the adhesives industry. For example, ethylene is polymerized to polyethylene.

Perfuming and Masking Agents

Agents used in the formulation and manufacture of adhesives and sealants.

Perfuming and Masking Agents, Oil of Peppermint

Colorless to pale yellow clear liquid used as perfuming agent.

Perfuming and Masking Agents, Oil of Wintergreen

Pale yellow to reddish brown clear oil used as masking or perfuming agent.

Perfuming and Masking Agents, Terpinol

Material used as perfuming agent.

Peroxides

A group of compounds with the structure R−O−O−R. The O−O group in a peroxide is called the peroxide group or peroxo group.

Petrolatum

A petroleum-based semi solid.

Photo-Curing Materials/Photoinitiators

Molecules that create reactive species in the form of free radicals, cations, or anions when exposed to UV or visible radiation are called photoinitiators. They add themselves to monomers or oligomers to initiate the polymerization process. Photoinitiators are used in combination with monomers and oligomers in UV-curing systems.

Plasticizers

Plasticizers are among the modifiers 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, but may also increase apparent tack by providing greater deformability.²

Plasticizers, Adipates

Salts and esters of adipic acid.

Plasticizers, Benzoates

Benzoate plasticizers, such as the glycol-, diethylengylcol-, and triethyleneglycol esters, are obtained by transesterification of methyl benzoate with the corresponding diol.

Plasticizers, Butyl Benzyl Phthalate

Clear, colorless liquid with a mild odor. Finds use in sealants, foams, adhesives, and coatings.

Plasticizers, Castor Oil (Raw/Refined)

Castor oil is frequently used as a plasticizer for inks, lacquers, and adhesives.

Plasticizers, Dibutyl Phthalate

A colorless, odorless liquid commonly used as a solvent and plasticizer.

Plasticizers, Dicyclohexyl Phthalate

A phthalate ester and a diester.

Plasticizers, Diethylene Glycol Dibenzoate

Diethylene glycol dibenzoate is a clear and colorless to slightly straw-colored liquid. The substance has a faint aromatic odor and is slightly soluble in water. The substance is produced from benzoic acids and belongs to the glycol benzoate ester group, which is chemically stable and has high-boiling-point diesters.

Diethylene glycol dibenzoate is very soluble in different polymers and is used as a plasticizer in polyvinyl acetates (PCAc) and polyvinyl chloride (PVC) coatings, in floor coverings, and plastisols (roof coatings). Other applications include as a plasticizer in glue, caulks, sealants, and paints. It is approved by the Food and Drug Administration (FDA) for use in plastic and glues for food packaging.

Plasticizers, Diisobutyl Adipate

A fatty acid ester.

Plasticizers, Diisodecyl Adipate

Light-colored, oily liquid used as a plasticizer for polymers.

Plasticizers, Diisononyl Phthalate

Phthalate used as a plasticizer.

Plasticizers, Diisooctyl Phthalate

Material used as a crosslinking agent or plasticizer.

Plasticizers, Dioctyl Adipate

Raw material used as a way to disperse pigments.

Plasticizers, Dioctyl Phthalate

Raw material used as a plasticizer.

Plasticizers, Diphenyl Phthalate

The diphenyl ester ofbenzene-1, 2-dicarboxylic acid, used as a phthalate ester and a diester.

Plasticizers, Dipropylene Glycol Dibenzoate

Dipropylene glycol dibenzoate, or 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.

Plasticizers, Epoxidized

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

Plasticizers, Mineral Oil

Petroleum-based additives used to increase the plasticity or decrease the viscosity of a material.

Plasticizers, Phosphates

Phosphate plasticizers are most commonly used to impart flame-resistant properties to adhesives, sealants, and plastics.

Plasticizers, Phthalates

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

Plasticizers, Polymerics

Polymerics are high-molecular-weight plasticizers used for demanding applications where typical plasticizers fail from migration out of the adhesive or sealant overtime. These plasticizers provide the highest levels of permanence and superior performance under demanding conditions such as heat, humidity, and weathering, as well as soapy water and solvent extraction.

Plasticizers, 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.

Plasticizers, Silicone

Silicone plasticizers can be added to soften sealant and adhesive formulations while avoiding problems (e.g., yellowing, shrinkage) associated with organic plasticizers.

Plasticizers, Tricresyl Phosphate

Abbreviated TCP, tricresyl phosphate is an organophosphate compound that is used as a plasticizer.

Plasticizers, Trimellitates

Colorless to slightly yellow liquid used as a plasticizer.

Plasticizers, Triphenyl Phosphate

Derived from a phenol, it is used as a flame retardant and a plasticizer.

Plastisols

A plastisol is a liquid that can be converted into a solid plastic by heating.

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.

Preservatives, Benzoic Acid

A white crystalline substance present in benzoin and other plant resins.

Preservatives, Biocides

A biocide is a chemical agent capable of killing organisms responsible for microbiological degradation.

Preservatives, Fungicides

Chemical compounds used to destroy or inhibit the growth of fungi or fungal spores.

Preservatives, Sodium Benzoate

The sodium salt of benzoic acid.

Preservatives, Wet-State

Wet-state preservatives are added to protect, prevent, or retard decay, discoloration, or spoilage during use or storage. (See also Preservatives, Biocides and Preservatives, Fungicides.)

Pressure-Sensitive Substrates

Adhesive products that provide permanent adhesion on a variety of dissimilar materials with the use of minimal pressure and without the need for solvents, water, or heat for activation. Adhesives may be cast as free transfer films on paper release liners or on various film backings for laminating to paper, plastic, metal, glass, wood, low-energy surfaces, and other substrates in industrial applications. Good cohesive strength allows clean removal of these high-tack materials without adhesive residue.

Pressure-Sensitive Substrates, Film

Materials commonly used for plastic films include: polyester; polyolefins; polyvinyl chloride; cellulose acetate; cellophane; most thermoplastics; and additives such as processing aids, colorants, and stabilizers.⁴ (See also Pressure-Sensitive Substrates.)

Pressure-Sensitive Substrates, Foam

The use of foam for a tape backing, particularly for double-sided tapes, is increasing in popularity. Not only does foam backing enable intimate contact of the coated pressure-sensitive adhesive to the irregular surfaces, but also, in remove the adhesive from the surface, expansion of the foam absorbs some of the applied stress. Foams are available in a range of materials, including polyethylene, polypropylene, natural and synthetic rubbers, polyvinyl chloride, acrylic, polyurethane, and silicone.² (See also Pressure-Sensitive Substrates.)

Pressure-Sensitive Substrates, Foil

Aluminum foil is the most common metal foil used in adhesive-tape backings, with some copper foil and very little lead foil. Most of it is produced by transfer spread and sold with the release paper liner in place.² (See also Pressure-Sensitive Substrates.)

Pressure-Sensitive Substrates, Papers

Paper that is used for pressure-sensitive adhesives is commercially available in two major forms: creped and flat back. Each is available in various weights. They must be porous enough to adsorb the saturants quickly during the saturation process, and the raw paper must have enough wet strength to maintain integrity following saturation and during the initial drying process until enough water has been removed. This is usually aided by incorporating a wet-strength additive as a beater addition during the paper making process, often a trace of melamineformaldehyde.² (See also Pressure-Sensitive Substrates.)

Pressure-Sensitive Substrates, Tape

A strong, narrow strip or band of paper that is permanently tacky at room temperature and will adhere to a surface with only light pressure. It requires no water, solvent, or heat to activate the adhesive to create a bond.⁴ (See also Pressure-Sensitive Substrates.)

Processing Aids

Additive designed to be added to a water bath to prevent sticking of hot-melt adhesives.

Release Agents

Chemical used to prevent other materials from bonding to surfaces.

Release Coatings

Since the1950s, silicone coatings have been widely used on many paper and film liners for the purpose of releasing a variety of pressure-sensitive adhesive-coated materials. Up until the 1970s, these silicone release chemistries were based on high-molecular-weight reactive silicone polymers dissolved at low solids in such flammable/toxic solvents as toluene and xylene, and they all required high-temperature oven processing to cure them into durable release coatings.

The 1970s introduced a series of governmental regulations that put serious restrictions on the handling/disposal of the carrier solvents, driving the release-coating industry to push for friendlier silicone chemistries such as water-based silicone emulsions and thermal, solventless chemistries based on reactive silicone fluids.

The 1980s saw the commercialization of two families of ultraviolet light (UV)-and electron beam (EB)-curable silicone release coatings that, along with being 100% convertible, provided for non-thermal, room-temperature-curing chemistries—UV/EB “free radical”-curable acrylate silicones and UV/EB “cationic acid”-curable epoxy silicones.

By 1990, a new generation of cationic UV-cure epoxy-silicone chemistries was developed. The current generation of cationic UV-silicone technology provides a variety of targeted release characteristics on both paper and film substrates.

Rheology Modifiers

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 and 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.

Softeners and Anti-Blocking Agents

Substances that reduce hardness, or reduce blocking to allow easier processing and handling.

Softeners and Anti-Blocking Agents, Beeswax

Natural wax composed mainly of esters of fatty acids and various long-chain alcohols.

Softeners and Anti-Blocking Agents, Coal Tar Oils

Oils obtained by the destructive distillation of bituminous coal.

Softeners and Anti-Blocking Agents, Hydrogenated Vegetable Oils

Oils made solid by way of hydrogenation process.

Softeners and Anti-Blocking Agents, Paraffin Waxes

Waxes used as a softener in a formulation. (See also Waxes.)

Softeners and Anti-Blocking Agents, Stearic Acid

Stearic acid is a waxy solid used in making candles, plastics, and other products, and for softening rubber.

Stabilizers

Stabilizers are chemicals added to a formulation to inhibit reactions between two or more other chemicals.

Stabilizers, Stearates

Stearates are the salts and esters of stearic acid.

Surface Conditioners and Modifiers

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

Surfactants and Dispersing Agents

A surface-active compound that reduces surface tension when dissolved in water or water solutions, or that reduces interfacial tension between two liquids, or between a liquid and a solid. There are three categories of surface-active agents: detergents, wetting agents, and emulsifiers. All three have the same basic chemical mechanism and differ chiefly in the nature of the surfaces involved. (See also Dispersing Agents.)

Surfactants and Dispersing Agents, Detergents

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

Surfactants and Dispersing Agents, Dispersing Agents

Additive used to make the dispersion process easier and more stable.

Surfactants and Dispersing Agents, 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 chemicals resistance.

Surfactants and Dispersing Agents, Wetting Agents

Substance used to reduce surface tension, thereby facilitating spreading or impregnation of a surface.

Tackifiers

Tackifiers are specialty resins used in the 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 maybe 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.

Thickening Agents

All adhesives and sealants must have the proper consistency or viscosity. If the combination of binders, pigments, fillers, and other additives results in a formulation that is too thin, thickening agents will be added to increase the viscosity. (See also Rheology Modifiers.)

Thickening Agents, Bentonites

Absorbent aluminum phyllosilicate clay consisting mostly of montmorillonite.

Thickening Agents, Methyl Cellulose

Methylcellulose is a chemical compound derived from cellulose. It is a hydrophilic white powder in pure form and dissolves in cold (but not in hot) water, forming a clear, viscous solution or gel.

Thickening Agents, Water-Based

Water-based agents are added to a formula to increase viscosity.            

Thixotropes

Thixotropes are materials used to modify adhesive rheology.

UV Absorbers

UV light can cause the degradation and discoloration of many polymeric materials. UV absorbers are stabilizers that are added to polymers that are usually exposed in an outdoor environment. While many plastics and rubbers are intrinsically protected from UV radiation because of high levels of pigment loadings such as carbon black or titanium dioxide, clear resins or coatings need protection from UV radiation. The most commonly used UV absorbers/stabilizers are called hindered-amine light stabilizers (HALS) and are based on piperidine structures.

Viscosity-and Flow-Control Agents

(See Thickening Agents and Rheology Modifiers.)

Water Repellents

Water repellents are used to make a substance hydrophobic.

Water-Treatment Chemicals

Water-treatment chemicals eliminate impurities used in feed water for process applications. They are also used to control corrosion and other damage to water-tube boilers, heat exchangers, cooling towers, and chillers. Water-treatment chemicals include ion exchange systems, chemical softening systems, demineralizers, and other chemical-control systems.

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 microcrystalline waxes, not only reduce melt viscosity and melt surface tension but also reinforce the hot melt by forming crystallites that resist deformation under load.³

Waxes, Dispersions

Material used as a surface modifier.

Waxes, Emulsions

A stable mixture of one or more waxes in water.

Waxes, Microcrystalline

Microcrystalline waxes can reinforce a hot melt by forming crystallites that resist deformation under load.

Waxes, Synthetic

A synthetic wax is made from animal, mineral, or vegetable sources but is altered and refined.

Wetting Agents

Substance used to reduce surface tension, thereby facilitating spreading or impregnation of a surface.