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Fillers and their Surface Modifiers in Polymer Applications
Applied Market Information, November 2007, Pages: 110
This report has been written to provide decision makers with an understanding of the fillers (and associated surface modifiers) industry and its main markets in plastics and rubbers (or elastomers). This industry comprises a complex set of businesses which overlap with many other business areas. It also serves of a number of almost self contained and widely differing markets within its overall scope. Many specialists within one of the specialised fillers areas, or the other business areas, need from time to time to look at filler opportunities that are outside of their own expertise. This report has been written to provide an overview of the fillers and surface modifiers businesses and markets for such people. It should have particular relevance for companies seeking new outlets for materials, where their traditional markets are mature or declining. In addition it will be of value to businesses requiring new uses for surplus or waste materials from other industries. The author has deliberately kept technical detail to a minimum and has focused on products and market opportunities. References to important publications providing greater detail have been provided.
The executive summary is followed by a description of the main features of the filler and modifier markets. There are then two chapters which outline the important technical matters influencing the use of fillers, and their surface modification. Next there are two chapters dealing with the production and properties of the main fillers and surface modifiers. This is followed by a description of the markets, broken down by filler type, applications area and polymer type. The future of the industry is then considered, with a brief discussion of supply and demand issues, followed by the main threats and opportunities that have been identified, and environmental and regulatory issues. Finally, the report concludes with listings of companies supplying fillers and modifiers, a glossary of acronyms and abbreviations, and some suggestions for further reading.
The report has been written from a European perspective, focussing primarily on the companies and markets within the enlarged European Union. However, it is impossible to study an industry such as this in isolation, when many of the markets have a global dimension and the larger companies a global presence; and hence some discussion of other regions and of world markets is also given. The European filler and polymer industries are both sectors of the broader global chemical industry, and the author has attempted to describe their significance in this context, whenever appropriate.
The report describes the use of as particulate fillers in polymer matrices. Unlike some other reports in this field, this one covers fillers for all three polymer types, i.e. thermoplastics, thermosets and rubbers. Sealants have also been included, but adhesives and surface coatings have not.
The particulate fillers covered include both natural products such as calcium carbonate and talc, and synthetics such as carbon black, precipitated silica and aluminium hydroxide. Whilst reinforcing fibres such as glass and carbon are beyond the scope of the report, some natural fibres and wood flour are included.
The term filler is taken to mean a material added at fairly high loadings, and so markets where particulate additives are used at low levels, such as pigments are excluded. One exception to this principle is the anti-block market, which uses many of the traditional fillers, albeit at very low levels, and hence it has been included. Similarly, some nanoparticulates are also included, even though they are meant for use at low levels, as their function is to replace traditional fillers used at higher loadings.
The report is also restricted to relatively small particles (under 100 micron); as particles larger than this are usually regarded as aggregates rather than fillers (although there is some overlap especially in polymer concretes and in engineered stone and some types of flooring).
Filler surface modifiers influence the interaction between a filler and a polymer, and hence they are a vital component of many filled systems, and they are included in the report for this reason. The surface modifiers covered are those that are in significant commercial use with fillers and which are capable of forming a chemical attachment to the filler surface. This excludes surfactants, which are only reversibly absorbed. The principal modifiers that are covered are fatty acids, organo-silanes and functionalised polymers.
1.1 Why This Report Has Been Written
1.2 Geographical Focus
1.3 Period under Review
1.4 Definitions and Scope
1.5 Structure of the Report
1.6 The Author
1.7 Sources of Information
2 Executive Summary and Conclusions
3 Background to the Fillers and Modifiers Businesses
4 Important Characteristics of Fillers
4.2 Chemical Composition
4.3 Specific Gravity
4.4 Powder Handling Properties
4.4.1 Bulk Density
4.6 Thermal Properties
4.6.1 Thermal Conductivity
4.6.2 Coefficient of Thermal Expansion
4.6.3 Thermal Stability
4.7 Optical Properties
4.8 Morphology (Particle Size and Shape)
4.8.1 Particle Size
4.8.2 Specific Surface Area (SSA)
4.8.3 Particle Shape
4.8.4 Oil Absorption (OA) and Particle Packing
5 Filler Surface Chemistry and Modification
5.2 Non-Coupling Modifiers
5.2.1 Fatty Acids
5.2.2 Other Non-Coupling Modifiers
5.3 Coupling Agents
5.3.2 Functionalised Polymers
5.3.3 Other Coupling Agents
5.4 Methods of Using Surface Modifiers
5.5 Use of Modifiers and the Monolayer Concept
5.5.1 Determination of the Actual Requirement
22.214.171.124 Viscosity Reduction of a Suspension
126.96.36.199 Settling Volume of a Suspension
188.8.131.52 Adsorption Isotherms
184.108.40.206 Dye Adsorption
5.6 Cost of Using Surface Modifiers
5.6.1 Modifier Costs
6 Principal Filler Types
6.1 Mineral Fillers Produced Directly from Natural Sources
6.1.1 Natural Carbonates
220.127.116.11 Calcium Carbonate (CaCO3)
18.104.22.168 Dolomite (CaCO3.MgCO3)
22.214.171.124 Magnesite MgCO3
6.1.2 Natural Crystalline Silicas, Quartz Etc
6.1.3 Diatomaceous Earths
6.1.8 Natural Fibres
126.96.36.199 Wood flours
188.8.131.52 Natural Fibres
6.2 Synthetic Fillers
6.2.1 Carbon Black
6.2.2 Synthetic Silicas
184.108.40.206 Fumed Silica
220.127.116.11 Precipitated Silica
6.2.3 Precipitated Calcium Carbonate (PCC)
6.2.4 Alumina Trihydrate (ATH)
6.2.5 Magnesium Hydroxide
7 Principal Modifiers
7.1 Fatty Acids
7.3 Functionalised Polymers
7.4 Other Modifiers (Titanates, Solplus etc)
8.2 End User Markets by Filler
8.2.1 Carbon Black
8.2.2 Precipitated Silica
8.2.3 Fumed Silica
8.2.4 Precipitated Calcium Carbonate (PCC)
8.2.5 Aluminium Hydroxide (Alumina trihydrate, ATH)
8.2.6 Magnesium Hydroxide
8.2.7 Natural Calcium Carbonates
8.2.9 Kaolins (Clays)
8.2.11 Crystalline Silicas (Quartz and cristobalite)
8.2.13 Barium Sulphate
8.2.14 Natural Fibres
8.3. Markets by Application
18.104.22.168 Non-Tyre Applications
8.3.2 Fire Retardancy
8.3.3 Electric Cables
8.3.6 Solid Surfaces
8.3.7 Household Appliances or White Goods
8.3.8 Breathable or Microporous Film
22.214.171.124 Flexible Packaging
126.96.36.199 Polymer Foam
188.8.131.52 Rigid Packaging
8.3.11 Masterbatch Production
8.3.12 Anti-Block Additives
8.3.13 Wood Polymer Composites
8.4 Markets by Polymer
8.5 Markets for Surface Modifiers
8.5.1 Fatty Acids
8.5.3 Functionalised Polymers
9 Supply and Demand Issues, Threats and Opportunities
10 Filler and Modifier Companies
10.1 Natural Product Fillers
10.2 Synthetic Product Fillers
10.3 Organo-silane Coupling agents
10.4 Functionalised polymeric modifiers
10.5 Fatty Acids
10.6 Other Modifiers
11 Abbreviations and Acronyms
12 Useful Further Reading
This report has been written to provide decision makers with an understanding of the fillers (and associated surface modifiers) industry and its main markets in plastics and rubbers.
Particulate fillers play a major role in all types of polymers; thermoplastics, rubbers and thermosets. The main fillers by tonnage are carbon blacks and calcium carbonates, and the European market, including carbon black, is estimated at over 5 million tonnes with a 2007 value of 2.3 billion Euros. Even without carbon black it is estimated at over 3 million tonnes with a value of 1 billion Euros. Rubbers consume the most filler (about 60% of total by weight and 80% by value in Europe) followed by thermoplastics (30% by weight and 16% by value) and thermosets (10% by weight and 4% by value).
Filler surface modifiers are also vital to the success of the fillers business with about 13,500 tonnes valued at over 100 million Euros being consumed in Europe. They give rise to added value well in excess of their cost. As with fillers themselves, the biggest use is in rubbers.
The fillers and modifiers business is directly dependent on the fortunes of the polymer industry and of the world economy. The largest applications are in construction, wire and cable and automotives, especially tyres. Consumer products such as appliances are also significant users.
Fillers for polymers cover a number of different product types. The main classification is between those of natural origin produced by mining and mineral processing methods, and synthetics produced by chemical methods including precipitation and pyrolysis. The natural types are typified by calcium carbonates, talcs and clays and are low to medium priced products. The synthetics are typified by products such as carbon blacks, fumed and precipitated silicas and metal hydroxides. They are medium to high priced products and bring quite significant benefits to the polymer, such as high reinforcement or flame retardancy.
Carbon black ties with calcium carbonate for the largest use by weight, but far exceeds it by value. About 1.8 million tonnes were used in Europe in 2006. Carbon black fillers are predominately used in rubber applications, with tyres dominating. This filler is expected to grow in volume significantly, but with virtually all of the new capacity being installed in Asia. Environmental issues are amongst the factors preventing new capacity in Europe, but the shift of manufacturing to Asia is the main one. Carbon black has been under increasing attack from precipitated silicas in the tyre market. These materials have already taken a significant share of the tread market, especially in Europe and are expected to make further inroads.
Natural ground calcium carbonate (GCC) remains the workhorse product for the polymer industry, with about 2 million tonnes being consumed in Europe in 2006. About half of this is thought to have been fatty acid treated. The price of GCC varies very significantly with grade, and there are some quite high volume specialist products such as those used in microporous film. The main polymers in which GCC is used are polyvinyl chloride (PVC), polyolefins, unsaturated polyester resin and elastomers. The PVC market is under threat in Europe, with declining use of this material resulting from environmental concerns, but this should be offset by the use of GCC in replacement polymers.
Companies operating in the fillers area tend to be large scale and to specialise in one or two filler types. They also have a global presence, which is now required by some of their large OEM customers (original equipment makers). In most cases the materials mined have a number of applications in addition to their use as fillers, and quite frequently these are larger than the filler one. For example; clays and calcium carbonates have wide use in the paper industry. Clays are also widely used in ceramics. Even the synthetic fillers have large non-polymer applications. Thus precipitated calcium carbonate is used in large quantities in the paper industry. Alumina trihydrate is used in paper and dentifrice (toothpaste and powders) and precipitated silica in paper and agriculture.
Filler markets are also quite diverse; ranging from low margin, high volume ones with just a few powerful customers, to low volume, high margin ones with many more small accounts. Most of the markets require a significant level of technical support and are under continual cost and substitution pressures.
Only a few of the markets are large enough in value to support the large cost of developing radically new filler and modifier types and uses. Thus applications like tyres tend to lead the way in this; as exemplified by the highly dispersing precipitated silicas, improved carbon blacks and low volatile organic compound coupling agents recently developed for low rolling resistance tyres.
While fillers are largely well established commodities, there have been some significant changes in relative consumption over recent times. The most dramatic of these has been the move of precipitated silica into automotive tyre treads at the expense of carbon black. This development has occurred due to changes in market requirements, namely for increased fuel economy. This new requirement has spurred two apparently mature technologies (carbon black and precipitated silica) to evolve new improved product forms, and also led to more efficient and environmentally friendly surface modifiers. These changes in the tyre market for fillers still have significant potential for further development.
Flame retardant fillers are another success story, driven by environmental concerns. Fillers such as aluminium and magnesium hydroxides can give high levels of fire retardancy without the smoke, corrosive and possibly toxic, gas emissions associated with competing halogen/antimony oxide combinations. As a result, they are benefiting greatly from the move to halogen-free, fire retardant specifications, a trend which is expected to continue. This growth is likely to get a boost in the medium term in Europe, due to the implementation of the Construction Product Directive (CPD). This European Directive includes acidity as an additional criterion to classify the fire performance of cables, and this is expected to accelerate the switch from PVC to halogen-free wire and cable compounds.
Wood polymer composites based on wood flour and recycled polymers have taken off spectacularly in North America, with annual growth rates of 20% or more and a present volume of about 600,000 tonnes of compound there. So far this growth has not been reflected in Europe, where only about 40,000 tonnes were used in 2006, but there are some signs that Europe is beginning to follow the North American trend.
There is also increasing interest in natural fibre based composites, which are already well established in automotive applications in both Europe and North America.
Nanoclays must currently be put into the disappointing category. As recently as 2002, there were predictions that they were going to achieve a dominant position in the major filled polyolefin markets. So far this has not been realised, mainly due to technical limitations with the current generation of products. In particular the exceptional properties seen in certain polyamides have not been achieved in polyolefins. As a result, nanoclays remain niche products, used mainly for gas barrier properties in polyamides and as flame retardant synergists. They still have considerable potential if the difficult technical challenges can be overcome at a reasonable cost.
Environmental issues are also creating another opportunity, which is the replacement of fillers containing crystalline silicas such as quartz in more than trace amounts. This is because of the health hazards associated with crystalline silicas, especially fine powders in the respirable range. Currently attention is on the very fine quartz and cristobalite flours. A number of alternatives are being investigated.
Recycling of polymers will become an increasingly important issue and must impact on patterns of filler use. It is still too early to see most of the consequences. One trend that is emerging is the use of post-consumer polyolefins, especially widely available polyethylenes, to make products such as lightweight kerbstones. Filler is necessary to achieve rigidity and heat distortion resistance and this could become a major market for calcium carbonate and talcs. This market is also beginning to see a demand for recycled fillers, so that the complete finished article can have as high a recycled content as possible. So far suitable recycled filler product does not seem to have become available.
On the downside, environmental concerns may well negatively affect some of the important volume markets. Two cases in point in Europe are microporous film and plastic bags. The main application for microporous film is in disposable nappies, which are under pressure from environmentalists. There is also a drive to significantly reduce the number of plastic bags used for shopping.
We are beginning to see serious concern in Europe over the effects of mining and the use of non-renewable resources. Very recently the European parliament has called for a reduction of at least 50% in the use of non-renewable resources by 2030. They are also holding stakeholder dialogues with the most resource-intensive extraction sectors in order to set targets and measures for improving resource use. This situation is evolving rapidly and will create both opportunities and threats for filler producers and users.
Surface modification remains a very important way of adding value to fillers, as it can improve polymer compounding and end product performance. Fatty acids and organo-silanes are used almost exclusively when the filler is pre-treated. When the modifier is added during compounding then organo-silanes and functionalised polymers are the additives most commonly used.
By far the most important modifiers by tonnage and value are the sulphur-functional silanes used with precipitated silica in the green tyre technology, which has become very popular, especially in Europe. This is partly because they are used at much higher loadings than the conventional level of about 1%. This market has been very active, both because of its value and because of the expiry of a key Degussa (now Evonik) patent covering the original tetrasulphidic products. A number of new products have been developed to meet the demands of this market and to counteract the environmental issues caused by VOC emissions (volatile organic compounds) from conventional silanes.
Functionalised polymer modifiers, especially maleic acid grafted polyolefins are also growing rapidly. This is largely due to their importance in wood polymer composites, a large market in North America with good growth prospects in Europe. They also play an important role in composites based on nanoclays, and this may become an important market for them if technical limitations of the nanoclays can be overcome and they live up to early expectations.
Natural Product Fillers
- J M Huber
- U.S. silica
- RT Vanderbilit
Synthetic Product Fillers
- Cabot Corporation
- Columbian Carbon
- Wacker Chemie
- PPG Industries
- Shiriashi Calcium
- Dead Sea Periclase (DSP)
- Kyowa Chemical Industry
- SMI (Specialty Minerals)
- Co-op Chemical Company
Organo-silane Coupling Agents
- Dow Corning
Functionalised Polymeric Modifiers
- EI DuPont
- Crompton Corporation
- Kenrich Petrochemicals
- Lubrizol Advanced Materials