Is there a lot of glue in things around us

The glue accounts for less than a percent of the mass and about 5% of the cost of complex machines – cars, computers, smartphones, aircraft, space rockets. But without glue, all of the above cannot be assembled – at least in our usual compact form. Correspondent «PM “visited Dusseldorf at the headquarters of Henkel – the world leader in the adhesive technology market – and learned, why our life without glue would be much harder, than it is.

Henkel’s headquarters in Düsseldorf is a city within a city: it employs 10 thousand people, has its own streets and even a “historic center” – a neatly restored building rented by Fritz Henkel in 1878 to produce the popular “Bleaching Soda”. Almost 150 years later, Henkel has grown into a huge company with nearly $ 20 billion in annual revenues and factories around the world.

Henkel headquarters in Düsseldorf
Henkel headquarters in Düsseldorf In the homeland of the company, in Dusseldorf (Germany), Henkel’s headquarters is a city within a city. It houses a small part of production, offices and a research center. The industrial premises of the last century have been reconstructed and used as offices.

The company now continues to produce laundry detergents and other household chemicals, as well as cosmetics (the range has expanded greatly after the merger with Schwarzkopf in 1995) and after the acquisition of Sichel-Werke in 1962 – adhesives. The famous Moment glue (look abroad for it under the name Pattex) has been one of Henkel’s most recognizable brands since the late 1970s. But in Düsseldorf, we were more interested in the lesser-known things – the huge variety of adhesive solutions used in industry to assemble everything from smartphones to electric vehicles. If anyone understands them, it is Henkel specialists: the company provides more than half of the market demand for adhesive solutions. It is very likely that the high-tech adhesives created in Düsseldorf hold the parts of the computer or smartphone from which you are reading this article together.

Henkel's story began with laundry detergents
Henkel’s story began with laundry detergents Persil, one of the first Henkel brands, recently celebrated its 110th anniversary.

Smaller and stronger

The compacting of electronic devices is achieved not least through gluing. Take a look at a smartphone camera, for example: it’s like a layer cake of dozens of lenses, filters, and electronic components, all held together by very thin glue lines. Now imagine that at least one mechanical element was used to fasten each of them – a bolt, a screw, or at least a fastener like a carpentry “dovetail”. How much would the chamber’s mass and dimensions increase? How complicated and, therefore, would the assembly cost rise?

To create one chamber, not one glue is used, but several adhesives with very different properties. Some conduct electricity, others work as insulators, some serve as UV filters, others are completely transparent, and all of them ensure the fastening of parts and their reliable fixation under temperature extremes and shock loads.

The smartphone camera uses about 20 types of adhesive solutions
The smartphone camera uses about 20 types of adhesive solutions
Different types of adhesives hold camera parts, provide electrical conductivity and insulation, and protect lenses from mechanical damage.

And this is just a camera (and there can be from three to eight of them in the newest models of smartphones). In total, there are more than twenty parts in a mobile phone, for the assembly of which fifty varieties of glue are used. Touchscreen glass is placed on conductive electricity and absolutely transparent glue; A thin, flexible adhesive layer holds the fingerprint sensor in place; the data buses are coated with special adhesive coatings for flexibility. Some of the compounds play a protective role, some fills cavities, protects the electronics from moisture, vibration and shock.

Lighter and greener

Without adhesive joints, the car would weigh 15% more – for a car, this is equivalent to the difference between an empty cabin and five passengers. The lighter the vehicle weight, the lower the fuel consumption, which means that the car pollutes the environment less. But glued joints simplify not only operation, but also the assembly of the car: it is easier to glue the parts than to weld or connect with bolts and nuts, which means that less energy and labor will be spent on production at the plant.

Electric cars are unthinkable without many types of adhesive solutions
Electric cars are unthinkable without many types of adhesive solutions
Adhesive solutions allow joining parts of machines and mechanisms, while maintaining a minimum specific weight of the structure. This is especially true for electric vehicles with their heavy batteries.

The more manufacturers care about the environment, the more important the adhesive bonds become. Without them, for example, it is impossible to imagine an electric car. Adhesive substances with exceptional thermal conductivity protect batteries from overheating; assembly adhesives reduce the weight of the battery, and sealants and functional coatings protect batteries from vibration and other external influences, and parts surrounding the battery from leaks, making the electric car reliable and safe.

To each his own

Whenever we need to glue a broken flower pot or join parts of a joinery, we go to the store and buy glue for ceramics, glass, wood – or general purpose. But in industry, things are a little more complicated. More than one million customers turn to Henkel Adhesive Technology every year. Many of them are satisfied with existing solutions – of those 80 thousand options that have already been developed by the company’s technologists. And when none of the ready-made solutions meets the technical specifications, scientists from R&D centers get down to business (there are already more than 20 of them in the world, and new ones are constantly being opened). Based on 40 basic technologies, they create new materials – with properties that meet the needs of the customer.

The path from TK to a ready-made solution can take years. Car companies, for example, turn to Henkel one and a half to two years before a new model appears on the market. During this time, the company manages to select and test several options that meet the specified requirements. Then, from the proposed options, one is chosen – using computer simulations (if the adhesive is required, for example, to absorb vibrations) or using field tests – if we are talking, for example, about compounds that will hold together the chassis of a car.

Looking ahead

When the PM reporter asked Henkel to name a couple of the most amazing products, he thought he would be told about the world’s strongest glue. Or about the lightest, or about the most transparent – in a word, something from the “Book of Records”. But it turned out that the company does not think of superlatives. Instead, we were told about perhaps the most amazing Henkel technology, which allows you to turn wood into a strong, durable and environmentally friendly building material.

The company has been producing Loctite wood structural adhesives since the late eighties, and during this time has made great strides in both strengthening the bond strength and getting rid of toxic solvents – today’s Loctite solutions do not contain them at all.

Without these adhesives, today’s “green” turn in architecture would not have been possible, they explained to us in Dusseldorf. These amazing substances make it possible to securely anchor wooden beams and logs and even erect multi-story buildings from wood (the most famous example is the 18-story student residence in Vancouver).

Thanks to adhesive solutions, the architects manage to erect monumental and at the same time harmoniously complementing the natural landscape structures – such as the famous Neckertal tree path in Switzerland or the Swiss elephant enclosure at the Zurich Zoo. Free from toxic solvents, Loctite wood adhesives maintain the properties of wood – and at the same time make it as reliable as concrete. Henkel hopes that in the near future, thanks to their development, wood will be able to, if not replace concrete, then make it a worthy “green” alternative.

Iron pull

Despite the fact that the company is more willing to talk about the environment than about its super adhesives, the company has something to brag about. At least by the experiment of 2017, in which three grams of Loctite HY 4070 universal glue managed to hold a 208-ton freight train.

A spectacular demonstration was held at the Düsseldorf railway station. Three grams of Loctite glue from a special syringe was applied to a thick metal plate, which was then screwed to the carriage and glued to another similar plate. We waited half an hour, and the train started off – and with it the 208-ton train, which was glued tightly.

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