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‘Flattening’ refers toThe book back can be completely flattened, and the cross page image is not broken by the middle seamAlbums, photography collections, recipes, map books, hardcover brochures, business notebooks, and other books that need to be spread out for reading or display are required to be spread out 180 degrees. Ordinary back glue often cannot do it – it will bounce back when opened, the back of the book will arch up, and it is easy to crack at the cross page. This article clarifies:What problems should be solved with a 180 ° flat layout, what scenarios is S-391 suitable for, how to choose, and which pitfalls are easiest to step on.
180 ° Flat Spread=After the book is spread out, the left and right pages can be flattened into a nearly 180 ° plane, without arching or rebounding the back of the book, and with continuous cross page images.
Typical scenarios that require it:
If a booklet can be easily flipped over and does not need to be completely flattened, it can be covered with universal adhesive;Only when leveling itself is a part of the reading experience, is it worth spreading glue.
Applicable to:albumPhoto bookrecipeBusiness Notebook
After the adhesive is cured, ifSlightly hard and brittleThe back of the book becomes a rigid hinge: when opened, it has a large rebound force, the back of the book arches, and the thin film at the cross page is stretched, which is prone to breakage and bursting over time.
The core of spreading is not “sticking more firmly”, butThe adhesive film should be flexible enough——It can stick together and bend with the pages without rebounding or breaking. This is the fundamental difference between flat glue and ordinary book and magazine back glue.
According to Sunlife product information,S-391 belongs to high-end flat adhesiveIt is characterized by a soft texture and supports 180 ° flat spreading, commonly used in binding scenarios such as business laptops that require flat spreading.
It is more suitable for:
Attention should be paid before use（The following are the items that need to be confirmed through actual testing, marked as’ Product knowledge to be confirmed ‘）：
Also known as “sharing”, the glue for different orders should also be divided into:
| variable | What need to be confirmed |
|---|---|
| Paper weight/coated or not | Copperplate paper, matte paper, and adhesive have different wettability, and thick paper tests flexibility and adhesive application more |
| Book core thickness | The thicker, the more the book backing adhesive layer and curing time need to be calculated separately |
| Binding speed | High speed lines should be matched with shorter opening times (about 15-20 seconds for low speeds, 5-10 seconds for medium speeds, and 2-7 seconds for high speeds) |
| Equipment temperature | Book adhesive is recommended to have the best viscosity and wettability at 160-180 ℃ |
| workshop environment | Temperature of 15-26 ℃ and humidity of about 50% are more stable |
promptIf there is a problem of “falling pages and not sticking firmly” after binding, don’t rush to replace the glue – according to Sunlife’s experience, about 90% of after-sales problems are caused by equipment temperature control failure (temperature control meter shows 160 ℃, actual glue slot is too low). Calibrating the equipment first is more effective than replacing the glue.
Q: Do I have to use specialized leveling glue for a 180 ° flat spread?
A: If leveling is the core experience (brochure, recipe, notebook), it is recommended to use a more flexible leveling adhesive; Ordinary booklets can be accessed with universal adhesive backing.
Q: Can S-391 be used on all books?
A: No. It is designed for the scenario of flat distribution. The suitability of extremely thick book cores and special paper needs to be tested, and it is recommended to conduct a small sample installation first.
Q: Why did you switch to flat glue or broken back?
A: First, check if the temperature is too high (carbonization becomes brittle), the amount of glue applied, the edge glue fit, and the equipment temperature control. Flattening is the result of the entire process, not just the glue.
Q: How do I determine if my order should be split equally?
A: See if readers will spread the book flat. Yes, it’s worth it; No, just regular adhesive backing.
Guangzhou Sunlife Trading Co., Ltd. specializes in the supply and application services of hot melt adhesive, covering back glue, edge glue, and flat glue for book binding. We can recommend models according to paper, equipment, and process conditions.
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