How to choose hot melt adhesive for book and magazine binding according to machine speed? Matching opening hours with production pace

Many book and magazine factories only ask “whether it sticks firmly” when changing the glue, but ignore itHow fast does the machine runThis key variable. The same glue, when used properly on a low-speed machine, may not be able to be brushed, adhered firmly, or have uneven book backs when used on high-speed lines. The root is there“Opening hoursWith yourstakt timeNo match. Let’s explain the matter of “selecting glue according to machine speed” in detail below (the specific model opening time is subject to Sunlife’s accompanying “Instructions/Process Card”).

1、 First of all, let me answer directly: the opening time is the “window period for glue to stick”

Hot melt adhesive applied to the back of a book is liquid, and when it comes into contact with air, the film gradually loses its stickiness. This “still sticky, permeable, and compact window” is calledOpening hoursThe book block must fall within this window from “gluing” to “pressing and shaping”, otherwise the glue has already formed a film and cannot penetrate even when pressed, resulting in falling pages, empty glue, and uneven book backs.The faster the machine, the shorter the time it takes for the book core to be glued and pressed, and the required opening time can actually be shorter; The slower the machine, the longer the adhesive is exposed, and the longer the opening time is required to provide a safety net. But the longer the opening time, the better – too long will slow down the shaping and make it easier to draw.

2、 Select the opening time according to the production pace (training actual testing interval)

The matching range provided by Sunlife’s “Instructions for the Use of Hot Melt Adhesive in Book Binding” is:

The logic is straightforward:Slow lines provide a long opening time as a backup (fearing that the glue will dry too quickly and be replenished), while fast lines provide a short opening time (fearing that the glue will be too sticky and slow to form)Choosing the wrong direction, using high-speed short open glue on low-speed lines will result in “peeling off the film before the book is pressed”, while using low-speed long open glue on high-speed lines will result in “sticking, drawing, and sticking on the back of the book”.

3、 In addition to speed, it also depends on these three supporting parameters

1. Operating temperature 160-180 ℃The optimal range for viscosity and wettability, incorrect temperature will change the actual opening time performance (training emphasizes glue pot temperature control, showing that 160 ℃ may actually only be 100 ℃, which is one of the root causes of “90% after-sales comes from temperature control”).
2. Curing time 3-5 minutesThe time from pressing the book to being able to cut and package is two different things from the opening time – the opening time is controlled by “gluing to pressing the book”, and the curing time is controlled by “pressing to being movable”.
3. Adhesive layer thicknessThe thin book core is about 0.4mm, the thick book core is about 0.8-1.0mm, and the adhesive layer will also slightly affect the penetration window.

4、 Practical selection list (for book and magazine factories)

1. First, calculate your own lineActual beat (Ben/Hour)Refer to the table above to set the opening time range.
2. Within the same gear, carefully select the model based on the paper (copperplate/adhesive/double adhesive/thin paper) and whether to spread it evenly (such as S-391).
3. Before changing models/accelerating,Try it in small batches firstSunlife has a 10 item acceptance checklist process, which involves running the “paper temperature machine glue” process before increasing the quantity.
4. After going online, use a temperature gun to check the actual temperature of the glue pot and maintain it at 160-180 ℃. Do not let the temperature control deviation “secretly” change the opening time.

5、 Relationship with Sunlife’s real business

Sunlife (Sunlife) hot melt adhesive for books and periodicals is divided into edge adhesive/back adhesive according to the scene, and regular flat adhesive and S-391 according to the flexibility. The opening time and usage temperature of different models are different. It is manufactured by Foshan Jucai Base and has been specializing in book binding for many years. When customers choose, Sunlife usually first asks “how fast is your line running, what kind of paper is it, and do you want it to be spread out”, and then matches the model corresponding to the opening time, instead of only giving “the stickiest one”. The accompanying “Instructions/Process Card” will clearly state the opening time, temperature, and adhesive layer of the model, and include the “Choose adhesive according to the rhythm” before shipment.

Explanation: The opening time interval of this article is a general reference provided in the training “Instructions for Use”. The specific model opening time is subject to Sunlife’s accompanying “Instructions for Use/Process Card”; Before speeding up/changing paper, it is necessary to conduct sample verification.