In the past, binding machines offered two types of binding: milled binding and sewn binding. But today, PUR glue is one of the industrial binding systems that solves many of today’s problems.
If we talk about milled binding, although it is more economical, it has the problem that the sheets can come unstuck if the book is opened too much or if it is used a lot.
Sewn binding, on the other hand, is more resistant, but it also has disadvantages. It is more expensive, as it is a more extensive manufacturing process, which means that the sheets inside the book have to be sewn together.
Later, attempts were made to bind with normal glue, but it is very difficult to bind photographic paper or couche paper without having previously sewn it, which made it impossible for a book to open completely flat.
This is where PUR glue binding came into being, because nowadays a lot of printing is done on photographic or couche paper, in order to achieve higher quality and lower costs.
What is PUR glue?
PUR glue is an optimal type of adhesive, highly resistant to environmental elements such as heat and humidity. It is based on a glue formulated on the basis of urethane polymer (Poly Urethane Reactive).
This adhesive has characteristics that make it unique and is preferred by bookbinding professionals for its high strength and durability on books. It is called PUR paperback binding.
At Indumarsan we have a wide variety of PUR glue, ideal for your bookbinding, as well as providing you with the right advice for your projects.
Rustic PUR binding
It is a type of binding that has become popular in recent years, to provide the book with greater durability and quality at the lowest possible manufacturing cost and without being sewn.
For PUR binding to be perfect bound, the paper fibre has to be prepared. Binding machines that use PUR glue must have a different milling system than traditional glue. Therefore, both the depth and the distance between grooves must be smaller than for traditional binding, in order to achieve a better penetration of the PUR glue.
It is highly recommended that PUR binding machines have a specific milling system for this type of work, but it is not necessary, as it is possible to bind simply by changing the application system by means of carriages, and using the same binding equipment.
In addition, books bound with PUR glue require longer curing time. Today, there are different manufacturers of PUR glue, and some of them offer several references, which have indications of different curing times as well as different chemical properties of the glue.
At present, PUR glue is applied by two systems: injectors and open tank. On single jaw machines, the injector system applies the glue on the back and on the courtesy. On high-production machines with several jaws, the PUR glue is usually applied on the back.
Characteristics of binding with PUR glue
The use of PUR glue for binding has a series of essential characteristics that define this system as one of the most widely used today. These characteristics are as follows:
→ It makes it easy to open the book almost flat without detaching any sheets.
→ It allows you to bind all types of book supports such as: laminates, offset, digital printing and photographic paper.
→ It is the best successor of the sewn binding due to its adhesion and flexibility.
→ It is resistant to high temperatures, which makes it a perfect binding to be sent anywhere and in any climate.
→ It is much faster than sewn binding and more economical than other types of binding.
→ It is ecological and environmentally friendly. Less PUR glue is required to bind a book than with other types of binding. In addition, this makes the finish more elegant and the excess glue does not show through the book.
What can I use PUR glue for?
PUR glue is particularly suitable for binding the following types of print:
▷ Corporate or product manuals.
▷ Price lists and account books.
▷ Periodical spine magazines.
▷ Books with spines that are to be used continuously and intensively.
▷ Edition books, such as essays, novels…etc.
The advantages of binding with PUR glue
When binding with PUR glue, we will obtain a series of advantages that we will not enjoy using any other type of adhesive. Among these advantages, we can highlight the following:
✅ It ensures the binding of all the pages of a book even when the book is opened flat..
✅ Allows the binding of any type of support, from photographic paper to digital printing, including plastics, laminates or offset, among others.
✅ Maintains its properties over time, so the book or publication in question will remain in optimum condition for long periods of time.
✅ It is highly resistant to extreme temperatures, withstanding temperatures ranging from -40 C° to 100 C°.
✅ It is more time-efficient, as the production process is considerably shorter than with other types of binding..
✅ Less glue is required. Because of its high adhesion and unquestionable quality, it makes the material more cost-effective. It also gives a more elegant feel to the customer, as less glue is used.
How do we know if the book was bound with PUR glue?
If you have a book in front of you and you want to know the type of binding that has been applied to it, you can do so if you know a couple of tricks:
Firstly, PUR glue leaves no traces on the binding. It is cleaner and more discreet than other bindings.
If you look at the spine of the book and you can see the different sheets, we are talking about a sewn paperback. On the other hand, if you cannot see them, it is most likely to be a PUR glue or, failing that, a milled paperback.
- Grasp the spine of the book with both hands and use force as if you were trying to tear it in half. This will depend on the number of pages in the book, but in general, if the spine bends when you do this, it is a conventional milled paperback. If it shows a stiffness, it is most likely to be PUR glue.
Have you solved your doubts about the use of PUR glue in bookbinding? Keep in mind that it is a very widespread system, valid for any type of support. In addition, the proliferation of photography has led to more durable and efficient binding techniques.
Also in short runs, which until some time ago used to be made with the milling technique, the use of PUR glue binding has become widespread.
At Indumarsan we are specialists in industrial adhesives, and we can advise you at all times when it comes to applying them in your bookbinding and other processes that require adhesion.
If you have any doubts about this type of adhesive or any other industrial adhesive system, we will be delighted to help you. Contact us so that we can help you.