2021 Raw Materials, Chemicals, Polymers, and Additives Handbook

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.

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, 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, Diisooctyl Phthalate

Material used as a crosslinking agent or plasticizer.

Plasticizers, Diisononyl Phthalate

Phthalate used as a 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.