Content

1) An Introduction to Plastics Additives 
1.1 Mixing and Blending Thermoplastic Compounds and Masterbatches 
1.2 Colouring Thermoplastics

2) Additives & Masterbatch
2.1  Anti Counterfieting
2.2  Antimicrobials / Biostabilisers
2.3  Antioxidants
2.4  Antistatic Agents
2.5  Biodegradable Plasticiser
2.6 Black Masterbatch
2.7  Blowing Agents
2.8  External Lubricants
2.9  Fillers/Extenders
2.10  Flame Retardants
2.11  Fragrances
2.12 Heat Stabilisers
2.13 Impact Modifiers
2.14 Internal Lubricants
2.15 Light Stabilisers
2.16 Pigments
2.17 Plasticisers
2.18 Process Aids
2.19 Reinforcements

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3) What do additives add to plastics?
3.1 Make Plastics Easier to Process
3.2 Make Plastics Look Good
3.3 Additives Save Money
3.4 Make Plastics Safe and Sound
3.5 Make Plastics Clean and Healthy
3.6 Make Plastics Work Longer
3.7 Additives Respect the Environment

4) Additives: A Buyers Guide

1. An Introduction To Plastics Additives

Every activity in modern life is influenced by plastics and many depend entirely on plastics products. Imagine cars without synthetic bumper, dashboards, steering wheels and switches; medicine without plastic hypodermic syringes and artificial hip joints. And what about telecommunications, dependent on plastic telephones, circuit boards and cable insulation. Our entertainment and leisure relies on the unique combination of characteristics offered by plastics in sports equipment and clothing, CDs, video and audio tape, television and cinema - indeed you wouldn't be able to read this over the internet without plastics!

All these plastics products are made from the essential polymer mixed with a complex blend of materials known collectively as additives. Without additives, plastics would not work, but with them they can be made safer, cleaner, tougher and more colourful. Additives cost money, of course, but by reducing production costs and making products last longer, they help us to save money and conserve the world's precious raw material reserves. In fact, our world to day would be a lot less safe, a lot more expensive and a great deal duller without the additives that turn basic polymers in to useful plastics.

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1.1 Mixing and Blending Thermoplastic Compounds and Masterbatches

Firstly we need to know the difference between Compound and Masterbatch/ Concentrates. Compound is compounded as a whole and purchased ready to use straight away ‘as is.’ Whereas Masterbatch is a pre-dispersed colour concentrate that is let down with natural polymer in ratios typically 1 to 5 % but can be much higher even up to 50%

There are different ways of mixing thermoplastics for compounding (Compounds & Masterbatches / Concentrates).. The choice of blender type and size are many and varied, the most common being Tumble, Ribbon or High Speed Blenders. Blends can be as little as 25kgs or 5 tonnes plus, depending on the size of the blending vessel being used though typically they are sized to make between 100 to 500kg batches.

Most Compound blends involve pellet feed and contain pigment levels of less than 1% and these are often made in Tumble or Ribbon blenders because they do not normally need high speed mixing to develop or homogenise the blend.

Masterbatches on the other hand, because they have pigment loadings of up to 75% and are usually made using powder polymers, often need high speed mixing in order to develop and homogenise the pigments within the blend.

Mixing can take place off line or on line. Both – (Compound & Masterbatch) are considered batch procedures where   the components are mixed with the polymer (in powder or pellet form) e.g. colourants, additives, fillers etc. These can be just single blends or multiple blends depending on the size of the production order and the blender capacity.

Read more about Mixing and Blending Thermoplastic Compounds and Masterbatches.

1.2 Colouring Thermoplastics

In order to offer the best colouring solution, one must first know the following criteria:

1. The polymer to be coloured.
2. The end application.
3. The processing conditions, temperature, and dwell time.
4. The type of process such as injection or blow moulding, film or sheet extrusion etc.
5. Indoor or outdoor use (if outdoor what country)
6. Lifetime colour expectation e.g., years or just a few months or weeks.
7. Minimum thickness of the end product.
8. Opacity requirements, e.g., fully opaque, translucent, transparent.
9. Food, toys, or medical applications.
10. Countries where the end product could be used.
11. Any extreme conditions of use during the lifetime of the end product e.g., in contact with temperatures in excess of 100c for long periods of time,
12. Chemical resistance requirements e.g., resistance to Acidic or Alkaline conditions or other specific chemicals.
13. Is the potential for warpage/distortion of real concern.

If the customer is able to divulge this information the experienced colour formulator can then select the most appropriate colourants for the application.

The key to any successful colour match is to ensure the most cost-effective formulation has been derived based on the information supplied.

Sometimes the customer is unable to gather all the information, it is then often left to the experienced colourist to come up with a formula that they consider to be a suitable for the application. The minimum information needed for an experienced colourist to offer a formula is for them to at least know the end application and the country or countries where the end product is likely to be used.

Read more about Colouring Thermoplastics.

2. Additives

 

2.1 Anti Counterfeiting

Function: 
 There are a number of ways manufacturers and brand owners can combat counterfeiting by employing one of several or indeed multilayer anti-counterfeiting technologies. Optical brighteners absorb ultraviolet and violet light then re-emit this energy at a higher wavelength, normally as a blue glow.

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2.2 Antimicrobials/Biostabilisers

Function: 
Help prevent deterioration of plastic materials where part of the material might be susceptible to microbiological attack. Such attacks can cause staining, discolouration, odour and loss of aesthetics but more importantly, loss of electrical insulating properties, hygiene and overall loss of mechanical properties in the material.

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2.3 Antioxidants

Function:
Help prevent "oxidation", the polymer reacting with oxygen. Oxidation can cause loss of impact strength, elongation, surface cracks and discolouration. Antioxidants help prevent thermal oxidation reactions when plastics are processed at high temperatures and light-assisted oxidation when plastics are exposed to UV light.

2.4 Antistatic Agents

Function:
Help to prevent the build up of static electric charge.  Plastics are generally insulating and so have the capacity to build up static charges on the surface which greatly disturb processing procedures and can be an issue for hygiene and aesthetics.

2.5 Biodegradable Plasticisers

Function:
Used to make plastics softer and more flexible and to enhance the degradability of the product.

2.5 Black Masterbatch

Function:

Black masterbatches have many uses and are a key material to everyday life, ranging from commodity applications such as waste bags to technical applications like pressure pipes. 

2.7 Blowing Agents

Function:
Form gases in the plastic to produce a foam material.  The blowing agents form gases by breaking down on heating at a pre-determined temperature and form a foam structure within the plastic's polymer matrix.

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2.8 External Lubricants

Function:
To prevent damage to plastics or the mould during processing. Applied to the material or directly to the machine to allow processing without damage.

2.9 Fillers/Extenders

Function:
Natural substances used to improve strength and lower the cost of the material. Usually mineral-based, fillers/extenders literally increase the overall "bulk" of the plastic.

2.10 Flame Retardants 

Function:
To prevent ignition or spread of flame in plastic material.  Plastics see substantial use in critical construction, electrical and transport applications which have to meet fire safety standards either by mandatory regulations or voluntary standards.  Flame retardants are added to plastics to meet these requirements.

2.11 Fragrances

Function:
Fragrances and deodorants for plastics are used in a variety of applications and arer products for the home.

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2.12 Heat Stabilisers

Function:
To prevent decomposition of the polymer during processing. Processing usually results in temperatures well above 180 deg celsius, which without the addition of heat stabilisers would result in the plastic material literally falling apart

2.13 Impact Modifiers

Function:
Enables plastic products to absorb shocks and resist impact without cracking. Particularly relevant for polyvinyl chloride (PVC), polystyrene (PS) and polypropylene (PP) materials.

2.14 Internal Lubricants

Function:
Used to improve processability of plastics by increasing the flowability. Internal lubricants improve the melt flow of material by lowering the viscosity and heat dissipation (also see Processing Aids)

2.15 Light Stabilisers

Function:
Used to inhibit the reactions in plastics which cause undesirable chemical degradation from exposure to UV light.

2.16 Pigments

Function:
Tiny particles used to create a particular colour.

2.17 Plasticisers

Function:
Used to make plastics softer and more flexible.

2.18 Process Aids

Function:
Used to improve processability of plastics by increasing the flowability.  Internal lubricants improve the melt flow of material by lowering the viscosity and heat dissipation (Also see Internal Lubricants) High-polymeric processing aids also improve flowability of PVC compounds.

2.19 Reinforcements

Function:
Used to reinforce or improve tensile strength, flexural strength and stiffness of the material. Often fibre-based.

3) What do Additives Add to Plastics?

Antiblock Additives in Flexible Packaging

At Flex-Pack Engineering we have many years of experience in developing antiblock solutions for our customers. But what is “blocking”?

Blocking is when your packaging or film sticks to itself. This happens due to a glass plate effect where all of the air between the layers of packaging has been removed or squeezed out, usually due to the polymer being extruded very smoothly and then wound tightly on to a roll. To avoid this sticking, you can put antiblock additives into the plastic which are usually inorganic minerals such as talc, synthetic silicas, or polymeric materials that are added into the polymer that create a rough surface on a micro layer. This rough surface on the polymer allows the two packaging layers to come into contact with each other and not stick or cling to one another. This is very desirable for the end-use consumer as it helps in the opening of flexible packaging products.

Finding Antiblock Solutions for Flexible Packaging

At Flex-Pack Engineering we have a great deal of experience in antiblock additive design and a robust network of trusted mineral suppliers and polymer additive vendors. When working with antiblock additives there are many factors to consider such as mineral selection, particle size, particle size distribution, top cut, and color. It is critical to design and choose minerals for antiblock additives that will not alter the color or clarity of the final flexible packaging product. We understand minerals, mineralogy, optimum particle size and particle size distributions to create the best antiblock additive effectiveness to be able to optimize your antiblock performance in end-use applications. We do this by selecting a number of mineral types and go through a compounding step to create very well disbursed masterbatches that will then be tested for their dispersion, to ensure their dispersion is pristine.

The second step is to take those masterbatches and use a second compounding step where we let those masterbatches down into a final resin that doesn’t contain any other antiblock additives. Our goal is to fully evaluate through the experiment the mineral or polymer additive loading level to be able to determine the optimum loading level for the best antiblock performance without impacting clarity, gloss, coefficient of friction, yellowness index or any other color performance criteria.

After these first two compounding steps are completed, we will do a third processing step which is making film. We’ll make a thin film usually on a blown film line because that process is most common and the particles are free to move within the polymer matrix so that they get to the surface, and you are not hindering the particles with anything but air, so they create a nice, rough surface to keep the subsequent layers from sticking together.

Once we make the film, we take it into the laboratory and perform tests to evaluate the performance of the antiblock additive. We look at blocking force, coefficient of friction, haze transmission and clarity, color change or effect, and also any gloss changes. We want the film to stay as glossy as possible yet still be somewhat rough so we can trap air between the layers so that the film will open up easily.

In the flexible packaging industry, the idea of using antiblock additives in films is well known but not usually studied under controlled conditions. As mineral companies find different minerals to be used as an antiblock additive, or they look at different blends of antiblock additives, they can improve the performance, especially around clarity and color. At Flex-Pack Engineering, we can bring our knowledge of the latest trends in antiblock mineral additives to optimize a high-performance solution for your situation.

Oftentimes in the production process if films are blocking, (sticking together), personnel don’t always take into consideration if they can use a better antiblock additive in the film formula. We have seen production problems related to sticking dealt with by turning up the feeder or using more antiblock additive than is really necessary. While these actions may reduce blocking, the other factors such as clarity, color, and gloss can be hindered because there is too much mineral in the process. It’s important to know and consider for each antiblock additive that you use what is the optimal loading level to give you the best performance so you can save money and produce a good and consistent product. This is where Flex-Pack Engineering can really help optimize your antiblock additive strategy.

Choose Flex-Pack Engineering for the Best Antiblock Solutions

While the concept of antiblock additives seems simple – you roughen the film surface to mitigate the film sticking together – if you really want to optimize for best performance, efficiency and cost, you really have to understand the type of antiblock additive you are working with, and what the limitations are so that you don’t use too little or too much antiblock in your process. If your customers can’t open their bags due to poor performing antiblock, ultimately they will stop buying from you.

It’s really important to understand how to best optimize antiblock additives to ensure high performance. And this also goes for all the additives you are using in your production process such as antistatic, slips, UV absorbers and hinderers, antifogs, and everything else. As the film manufacturer you really have to understand what it is you are buying from your masterbatch suppliers and how to best use them. The companies that do invest the time and resources to understand how to use additives are the world-class film producers.

At Flex-Pack Engineering we will bring our over 30 years of experience to guide the mineral suppliers, polymer additive suppliers, the compounders who are making the masterbatches, and ultimately the film manufacturers in terms of understanding their additives and impacts of those additives. We have been working with anti-block additives for a very long time. We are very technically and detail oriented. We have the knowledge and expertise to provide optimal antiblock additive solutions for the best performance.

Ready to have a conversation? Give us a call at 330-704- or fill out the request form on this page.

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