HDPE Bottles – A Complete Guide

Few could argue about the indispensable nature of high-density polyethylene (HDPE) bottles in our daily lives. They assist us in safely containing and carrying water, medication, cosmetics and many other liquid substances. Curious about who first invented them? Want to know more about their industrial value? How essential it is that we recycle them? Learn the answers to these questions and more here.

 

CONTENTS

1. HDPE Bottles: A Definition
2. Types of HDPE Bottles and Containers
3. A timeline of HDPE bottles
4. In the factory
5. Blow versus injection versus stretch
6. Global recycling initiatives
7. Benefits over other materials
8. Industrial Uses 2016 to 2026
9. Range of Sizes
10. UN certification
11. Bottom Line

 

HDPE Bottles: A Definition

 

HDPE plastic is one of the most common plastics used in manufacturing, due to the material’s durability and strength. While not as clear as Polyethylene Terephthalate (PET) plastic, HDPE bottles and containers can be translucent so that you are still able to see your product inside it. This type of plastic can also be colour matched and is popular in white.

Other identifying characteristics, which may cause a producer to specify the use of it rather than any other type of plastic, include the fact that it has a high-density, is taut with a good temperature resistance, all of which relates to its lack of chemical branching, and has an excellent water-vapour barrier.

HDPE bottles are also lightweight and food-and-beverage safe. The translucent nature of HDPE bottles makes it possible for consumers to view the amount of product still inside.

 

 

 

Types of HDPE Bottles & Containers

 

Because HDPE has moisture-barrier properties and chemical resistance, it has been found to be a perfect fit for many different bottling applications by organizations such as the American Chemistry Council, for example.

Examples of the types of HDPE bottles you are likely to come across in daily life include:

• blow-molded bottles;
• injection-molded bottles;
• non-carbonated beverage bottles, such as those for milk; and
• bottles designed to hold industrial chemicals, household cleaners and detergents.

HDPE bottles come in all shapes, sizes and colours.

 

A Timeline of HDPE Bottles

 

Inventor of the first man-made plastic, Alexander Parkes, claimed the substance was more versatile than rubber.

1862: Alexander Parkes invented Parkesine, the first man-made plastic, derived from cellulose. He presented his finding at the Great International Exhibition in London, but investors lost interest due to the cost of the raw materials.

1868: John Wesley Hyatt developed celluloid from a mixture of shred tissue paper, nitric acid and sulfuric acid. This first man-made thermoplastic is still used today for photographic film.

1891: Rayon was developed by Louis Marie Hilaire Bernigaut which, along with cellophane, were the precursors to the “plastics craze” of the roaring 1920s.

1907: New York chemist Leo Bakeland created Bakelight, which the military found useful in the production of weapons, as well as for electrical insulators, radios, cups, buttons, false gums and silverware handles.

1908: Dr Jacques Edwin Brandenberger discovered cellophane by applying liquid viscose to cloth – the aim being to make it waterproof. Although the experiment failed, the substance peeled off the cloth in a transparent film, which was a breakthrough.

1940s: Nylon, acrylic, neoprene, SBR and polyethylene were becoming widespread. In fact, between 1940 and 1945, the demand for plastic in the US grew immensely, tripling in production due to the war, public funding, oversight and the material’s versatility.

A range of inventions and discoveries gave way to various different types of plastic, including PVC or vinyl (found in vegetable oil bottles and food wraps), SaranTM, Teflon, PET (used in beverage and food containers), HDPE used in the making of milk and detergent bottles), LDPE (creates plastic bags and shrink wrap), PP (found in margarine and yoghurt containers) and PS (used to make egg cartons and disposable utensils).

1970s: Plastic bottles first came into regular use for soft drinks.

1977: The weight of these bottles was reduced from around 60 grams to just 48 grams.

1990: The highly progressive Coca-Cola Company began blending recycled plastic into its plastic beverage bottles.

2010: David de Rothschild led a crew on a 12 000-nautical-mile sea mission on Plastiki, which was the first ever ship created from recycled plastic bottles – with the movement towards sustainable living being a top priority among the eco-conscious.

In The Factory

 

 

Time to have a look at exactly how HDPE bottles are manufactured in the factory.

First off, three heated holding tanks commence the process – the primary one containing a natural gas derivative called ethane. The ethane is heated to well above boiling point (i.e. above +100°C) and is then pumped into a mixing tank.

From the third tank comes benzene which, when combined with UV radiation from a set of overhead lamps, serves to bring about the polymerization of ethane.

While this process describes how polyethylene is made, there is still a treatment process that the polyethylene needs to go through to become high-density polyethylene (HDPE). This involves pumping the chemical into a series of metal troughs that are wide, shallow and board-like. Instead of being allowed to cool, it is cooked at a low heat to allow for the release of any captured air and oxygen.

Next up, the troughs drain into a further series of upright metal molds that contain shredded wood fibre. Once the material has been allowed to cool for approximately eight hours, the HDPE boards can be shipped to retailers and wholesalers for use in various products.

 

For an in-depth look at HDPE follow this link to “HDPE A Complete Buyer’s Guide“

 

Concerned with keeping such shipments on schedule?

 

The secret is to take action early to avoid stress close to delivery date, by taking onboard the following vital tips:

• Set quality standards and deadlines at the outset;
• Request regular updates on progress;
• Hire a professional third party to carry out a pre-shipment inspection; and
• Persist through hickups and, ultimately, both timing and quality issues will be resolved.

 

Bottle Blow Molding

 

In bottle production, the process is identical to that described above, except that the HDPE is allowed to drain from the sitting troughs. The material is then kept in an air-tight heated tank, where a valve places measured dollops of it onto the heads of a series of air compressors, each of which fits into a metal mold shaped exactly like a bottle.

While the compressor pours air into the mold, ballooning out of the HDPE into the mold, another compressor functions to pump air out of the mold so the HDPE fits perfectly. To rid the air compressor of any excess plastic, a circular razor cuts it away; then it undergoes an acid bath and a separate water bath to clean it of any remaining residue so that it is ready for its next use.

When the ends of the cooling HDPE bottles-to-be have the consistency of putty, they are stamped into the shape of a bottle’s mouth and screw top. And, when cooled entirely, the mold splits in half to allow the new bottle that has been created to fall into a hopper or drum.

Last up, factory workers clean the bottles and buff off any rough edges or imperfections, resulting in the perfect bottles we see all around us in shops, homes and businesses.

 

Blow Versus Injection Versus Stretch

 

The world of plastics is certainly a complex one, but the most popular method of mass-producing bottles is the blow-molding process described above.

However, there are subtle differences between extrusion blow molding, injection blow molding and stretch blow molding. To differentiate these processes, see our bulleted explanations below:

• extrusion blow molding: air-blown into the desired shape while still warm; often chosen for its fast production rates and ability to produce complex parts.

• injection blow molding: plastic is injected into a core pin which is then rotated until the plastic has been inflated into the desire shape; cooling and ejection happen in one simple process, which takes longer than the other methods and is therefore used less often.

• stretch blow molding: small plastic resins are first stretched vertically and then horizontally to give the plastic’s molecules a cross shape, which has increased barrier strength; often chosen for low-volume speciality orders.

For buyers concerned about minor defects that may crop up during the injection-molding process, it is good to know these can typically be avoided simply by going with a supplier who knows to adjust the flow rate, temperature or pressure of the mold being employed.

Best to test a supplier’s knowledge beforehand!

However, quality issues can also extend from such minor faults in the surface of a product to more serious problems affecting its safety, performance or function.

Therefore, always go with a supplier who values the importance in their manufacturing work of: 1) the molding process, 2) the use of materials, 3) the design of tools and equipment, and 4) how these work in tandem.

 

Global Recycling Initiatives

 

According to the Institute of Scrap Metal Recycling Industries, the business potential of recycling plastics is seeing incremental growth.

In 2010, the US exported more than $940 million in plastic scrap for use in industry, which requires an 80 to 90% reduction in energy consumption when compared to producing plastic from virgin materials. Unfortunately, the country which used to accept up to 30% of the US’s recyclables – China – has taken steps to change this by informing the World Trade Organization that it will stop accepting imports of used plastic in 2018 in a bid to clean up its industrial pollution according to the Bloomberg article “China’s Blow to Recycling Boosts U.S.’s $185 Billion Plastic Bet”

While most of the recycled scrap is still “finding a home”, Peter Spendelow, a recycling policy analyst for the Oregon Department of Environmental Quality has commented, the situation could get a lot worse if new recycling markets are not found.

Fortunately, new markets are cropping up in India and Malaysia, with the latter having nearly quadrupled its US-sourced imports of mixed plastics last year, jumping from about 9 600 metric tons in 2016 to nearly 38 000 metric tons, according to the Institute of Scrap Recycling Industries.

Malaysia also imported substantially more recycled polyethylene, as did Thailand and Vietnam.

Brent Bell, president of recycling for Waste Management, the largest US landfill and recycling company, explains that as exports to China dropped, as part of the country’s broad campaign against “yang laji” or foreign garbage”, the US recycling industry had “really ramped up its volumes to India (and other countries in Southeast Asia).

In general the global economy hasn’t gone down, which means the demand for recycled feedstocks is still there,” he said, “We’re seeing these alternative markets really stepping up.”

 

UK Recycling Factoids

 

• HDPE milk bottles are one of the most widely recycled packaging items in the UK, with recoup figures showing they are recycled up to 79% of the time.

• On average, HDPE milk bottles in the UK are now 15% lighter than they were just three years ago.

• Additionally, innovative designs like the multi-award-winning Infini bottle mean it is now possible to reduce the weight of a standard bottle by up to 25%.

• On average, HDPE milk bottles in the UK contain up to 15% recycled material.

• But, in 2013, Nampak achieved a world first by incorporating 30% recycled HDPE into its Infini milk bottle – two years ahead of industry targets.

 

Benefits of HDPE bottles

 

In what ways are HDPE bottles superior to those made from other materials?

• it’s more impact resistant

• it’s more economical

• it has a greater barrier against moisture

• it provides a safer barrier against chemicals (specifically caustics and acids)

• it is light and therefore cheaper to transport

• it is recycled with greater ease

• it is weather resistant

• it resists mold and bacteria

 

 

Industrial Uses 2016 to 2026

 

On the basis of end users/consumers, the global HDPE bottles market can be divided up into the following four categories:

· Domestic use;
· Chemical industries;
· Cosmetic industries; and
· Pharmaceutical industries.

Because of the many benefits of the material, as mentioned in the infographic above, HDPE bottles are now used in the packaging of chemicals, detergents, cosmetics and fruit juices – over and above their traditional use in soft drinks and milk.

Based on the geographies, the global HDPE bottles market is segmented into five regions – North America, Latin America, Europe, APAC, and the Middle East & Africa.

Among the regions mentioned above, North America accounts for a significant share of HDPE bottles market, owing to the stringent regulations and norms in using a particular grade of plastic bottles.

HDPE bottles have gained a substantial proportion due to its chemical composition which poses the lowest threat to life and health as regards products fruit juices, milk, detergents and cleaners. The fact that all of these different products are primarily packaged in HDPE bottles today has given a massive boost to HDPE bottles market.

Europe is followed by the North American market in size, with Asia-Pacific emerging and anticipated to grow substantially in the near future due to its booming F&B industries, pharmaceutical industries, and increasing households with population rise.

In the Middle East & Africa, the market of HDPE bottles are in a nascent stage, while Latin America has witnessed a decent start. This market is primarily driven by household and individual demand, which is increasing worldwide.

A significant proportion of the working population, for example, travel for work and require and easy to carry, sturdy bottles for their needs. Additionally, HDPE bottles have been able to meet the requirements of a highly demanding global FMCG market.

The fact that these bottles can be recycled and therefore save energy and the environment has increased their popularity – research shows that in the US alone, one billion HDPE bottles were recycled in 2012.

A key driver in the HDPE bottle market is the stringent rules imposed by the US and other governments which inhibit the use of harmful plastic in manufacturing, which can emit harmful gasses and (oestrogenic) chemicals. Because of the high-quality demands of the HDPE bottles market, and the potential risks of poor-quality plastics contaminating the products once these bottles are filled, HDPE bottles have become the natural choice.

One restraint of this market is, however, the petroleum price. Because HDPE granules are made from petroleum, any price fluctuations in the product can have a knock-on effect on the prices of HDPE-produced bottles as well.

source: High Density Polyethylene (HDPE) Bottles Market: Global Industry Analysis and Opportunity Assessment 2016-2026

 

 

Range of Sizes

 

Any world-class plastic-production facility will be able to produce an extensive range of bottle sizes and neck finishes for their clients. For example, HDPE bottles can range from 250ml to five litres, on average, have up to 38mm necks for foil or screw cap closures, and can be clear or pigmented as per client specifications.

A frequently unknown fact about HDPE bottles is the wide variety of closure types available – from child-resistant, flip spout and lotion cap, to lock-down lotion pump, spouted cap, spray pump, trigger spray and ribbed screw cap, among others.

 

UN Certification

 

The United Nations (UN) Code is a mark indicating that the packaging in question has been tested in accordance with the recommendations of the United National Committee of Experts on the Transport of Dangerous Goods.

In place for almost 30 years since January 1991, all UN certified/approved packaging must first have passed a range of rigorous testing procedures, which were implemented to ensure that packaging for potentially hazardous materials can withstand normal conditions of transportation and represent the minimum acceptable design standards/requirements.

Packaging testing under the code includes:

• the drop test;
• the stacking test;
• the leak-proof test; and
• the hydrostatic test.

If all these tests are passes, the bottle in question is certified to be in “as for shipment” condition.

All jokes aside, the primary UN requirements document alone weighs 2kg (4.4lbs).

But, it makes senses that any type of packaging or bottles, when filled and closed for shipment, will consistently perform at a specific level.

source: http://www.contapack.com.au/UN–packaging–certification

On another note, we’d like to remind our readers that it is not just the HDPE products – in this case bottles – that should be certified as safe and above board as per international recommendations.

Additionally, the premises (factories and testing facilities) should also meet the necessary quality control and/or quality assurance specifications.

Laboratories and factories that have been certified in this way are likely to refer to such certifications on a regular basis, and will also display this information for all to see. So, if a third party is carrying out your premises inspection for you, tell him to keep his eyes peeled for this info, ideally posted up on the wall.

 

Bottom Line

 

High-density polyethylene: we know it for its superior bottle-making qualities when compared to other materials, including its benefits over and above other types of plastics.

It has a growing market, despite the recent China shut down, and that for both consumer and industrial purposes HDPE is preferred for its safety-related qualities.

Next up is the research and development (R&D) aspect of HDPE bottles. Who is doing this research; what scientific breakthroughs are they making; and why should you choose HDPE for your bottling range now, and in the future, over any other material currently on the market?

Follow JM Garcia as she transitions through the future of plastics recycling and production during the course of her scientific research – Catalyst:
Design Challenges for the Future of Plastics Recycling. We challenge you.

Do you have anything to add to the HDPE Bottle conversation? Then please feel free to leave a comment in the comments section below.