additives for plastics handbook || an overview of additives

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CHAPTER 1 An Overview of Additives From the very beginnings of the plastics industry, it has been necessary to add materials to a basic polymer resin in order, at least, to make it processable. It has also been clear that additive materials are necessary to modify a resin, to improve properties that are desirable, and to eliminate or mitigate properties that are undesirable. In developing additive systems, the plastics industry has learnt much from the earlier experience of the rubber industry, but the pace of development responding to market needs has produced research in completely new fields, developing additive systems using new chemistry. While the plastics industry is a major user of additives, it is not the only one. Additives overall can be classified as follows: Table 1.1 Types and uses of additives Type Main applications Additives Antimicrobials Coatings Colours Fine chemicals Heat and light stabilizers Optical brighteners Products, normally used in small quantities, which enhance the value of materials such as plastics, paints, colour prints, and lubricants, by improving their processability, performance, and appearance during manufacture and in use. Substances that prevent the growth of microbes and give consumer products such as soaps and toothpastes a medicated property. The broad term for paints, inks, and lacquers. While often associated with decoration, coatings also protect surfaces from corrosion and damage. Can be soluble dyes for textiles, leather, paper, or insoluble pigments for plastics, coatings, and printing inks. Highly complex functional intermediates or ingredients for 'high-tech' applications; for example, in the pharmaceutical, agrochemical, and electronic industries. Additives that prevent the degradation of plastics and coatings under the effects of heat, oxygen, and light. Chemicals which impart whiteness to textiles, detergents, paper, fibres, and plastics.

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Page 1: Additives for Plastics Handbook || An Overview of Additives

CHAPTER 1

An Overview of Additives

From the very beginnings of the plastics industry, it has been necessary to add materials to a basic polymer resin in order, at least, to make it processable. It has also been clear that additive materials are necessary to modify a resin, to improve properties that are desirable, and to eliminate or mitigate properties that are undesirable. In developing additive systems, the plastics industry has learnt much from the earlier experience of the rubber industry, but the pace of development responding to market needs has produced research in completely new fields, developing additive systems using new chemistry.

While the plastics industry is a major user of additives, it is not the only one. Additives overall can be classified as follows:

Table 1.1 Types and uses of additives

Type Main applications

Additives

Antimicrobials

Coatings

Colours

Fine chemicals

Heat and light stabilizers

Optical brighteners

Products, normally used in small quantities, which enhance the value of materials such as plastics, paints, colour prints, and lubricants, by improving their processability, performance, and appearance during manufacture and in use.

Substances that prevent the growth of microbes and give consumer products such as soaps and toothpastes a medicated property.

The broad term for paints, inks, and lacquers. While often associated with decoration, coatings also protect surfaces from corrosion and damage.

Can be soluble dyes for textiles, leather, paper, or insoluble pigments for plastics, coatings, and printing inks.

Highly complex functional intermediates or ingredients for 'high-tech' applications; for example, in the pharmaceutical, agrochemical, and electronic industries.

Additives that prevent the degradation of plastics and coatings under the effects of heat, oxygen, and light.

Chemicals which impart whiteness to textiles, detergents, paper, fibres, and plastics.

Page 2: Additives for Plastics Handbook || An Overview of Additives

2 An Additives for Plastics Handbook

Type Main applications

Photo/repro additives

Pigments

UV curing

Water treatments

Additives that, when irradiated with light, promote the hardening of printing inks, coatings, and adhesives, and chemically fix images used in electronic or graphic materials.

Colorants that remain undissolved before, during, and after application: they are used to colour plastics, inks, paints, and synthetic fibres.

Hardening of coatings and adhesives by means of ultraviolet light.

Help purify water for industrial and domestic applications. They also modify water as an agent for the processing of minerals and oils, and have a variety of properties to process water (for example, flocculants separate water from solid particles).

Source: Ciba Specialty Chemicals

For plastics, the range of additives is very large, involving the improvement of many properties:

Table 1.2 The main effect of additives on the properties of a compound

Physical properties Thermal conductivity Heat deflection temperature Abrasion resistance Impact strength Tensile strength Flexural strength Compressive strength Dielectric constant

Processing Exotherm Thixotropy Machinability Cost reduction

Calcium carbonate, calcium silicate. powdered aluminium. or copper

++ ++

= ----++

-= ++

-

Alumina, flint powder. carborundum. silica, molybdenum disulphide

++ ++

+ +

-= = = + +

----

Chopped glass

++ ++

+ + ++ ++ + + + + ++

---=

Mica, silica. powdered or flaked glass

++ ++

+ +

----++

-= --

Metallic fillers or alumina

++ ++

-++

= = = ++

-= ++

-

Colloidal silica, bentonite clay

-=

-= = = -=

-++ + + + +

Key: - decreases; ++ increases; = essentially no effect.

Page 3: Additives for Plastics Handbook || An Overview of Additives

An Overview of Additives 3

Table 1.3 Main types of additive for plastics^ and their functions

Type Examples Functions

Calcium carbonate, talc, mica Fillers and mineral reinforcements

Fibre reinforcements Aramid, carbon, glass, natural fibres

Colorants

Black and white pigments

Heat resistance

UV resistance

Flame retardants

Antistatics, conductives

Curing systems for thermosets

Cross-linking, coupling, compatibilizing

Plasticizers

Process modifiers, processing aids

Blowing agents

Lubricants

Other types

RecycUng additives

Pigments, liquid colours, colour pastes, dyestuffs, special effects

Carbon black, titanium dioxide

Antioxidants and stabilizers

UV stabilizers

Reactive, additive, other systems

Antistatic/conductive additives

Accelerators, curing agents, and catalysts

Forming cross-links between suitable polymer and other molecules

Mainly phthalates, but many systems are used

Lubricants and plasticizers, nucleating agents

Inert gas or gas-forming chemicals injected or mixed into a compound to react during processing

Lubricants, mould release agents, slip and anti-block

Barrier properties, shrinkage, acoustics, surfactants, antimicrobials

Impact modifiers, stabilizers

Adding bulk to a compound: increasingly used to improve stiffness, surface hardness

Mechanical strength: used as short fibre, long fibre, spheres

Virtually unlimited, added as powders or liquids: easier mixing, replacement of heavy metals

Also for improved UV resistance and (carbon black) electrical conductivity

Act to delay/prevent oxidation of polymer under heat, during processing or application

Delay/prevent oxidation of end-product under prolonged exposure to sunlight

Prevent ignition of polymer, promote extinguishing: types not producing smoke or fumes

Increase electrical conductivity, to prevent electrostatic discharge, sticking/clinging (e.g. films)

Initiate and control the cure of thermosetting resins

Cross-linking agents for thermoplastics; coupling agents, compatibilizers to promote bonds between polymers and additives

Improvement in processability, flexibility: used mainly in PVC, but limited use in other plastics

Improvement of mixing/blending; control of viscosity

Production of foams and expanded plastics; replacement of chlorofluorocarbons (CFCs)

Improvement in processing; release properties; reduced slippage and blocking with films

Giving specific properties

Used to improve/protect properties of waste plastics during mechanical recycling