There are two peak periods for the use of hot melt adhesives throughout the year, from June to September in summer and November to February in winter. These two seasons are catching up with the highest and lowest temperatures throughout the year. All this brings certain difficulties to the book binding.
According to the author's practice over the years, there has never been a problem with winter glue. The quality problems such as loose pages and degumming are all in the summer.
Why do quality problems occur with summer glue? I think the main reason is that the temperature in summer is too high, the operator's energy is not good, and the temperature of the glue and some small problems are not paid enough attention.
Let's take the example of the loose pages in the summer textbooks of 2009 as an example. Although the frequency of loose pages appeared in the textbooks of the season was only three, and the number was small, few were few and many were dozens. But the impact is not good, especially caused huge pressure on the printing house.
Loose book one: loose book pages
The reason is that the back of the book is not slotted (brushed). The unit removes the grooving knife, and uses the notch of the back milling knife to leave scratches on the spine instead of grooving.
Loose book 2: degumming
The adhesive layer is completely peeled off from the back of the book, and the back of the book is clean and there is no glue on it.
Loose book 3: The first 11 pages of this book, the last 65 pages are unbreakable.
From the analysis of the above three samples, combined with some practical problems we have encountered in the past, the following suggestions are made for the use of hot melt adhesive in high temperature weather in summer:
One is to make the slot as deep as possible and the slot as wide as possible. This can increase the amount of glue into the back of the book.
The second is to always pay attention to the glue temperature.
Due to the hot weather, operators often ignore the glue temperature. If the temperature of the glue is too low, the adhesion, permeability and tensile strength will also decrease, and the peeling of the glue layer is likely to occur. It is recommended that each machine is equipped with a thermometer to measure the temperature of the glue pot frequently. Don't believe the temperature control meter on the machine. Because of the long time, many temperature control meters are no longer allowed. The use temperature of glue is generally controlled at 155 ℃ ~ 160 ℃ is more appropriate.
The third is to concentrate on the operation.
Due to the hot weather, in order to catch up with the progress of some units, even 24 hours of shaft rotation, the operator is extremely fatigued, and it is easy to ignore some small problems. Such as:
(1) The first few books should be taken out every time the machine is turned on, because the books in the machine have been cured with adhesive backing when the machine is shut down. After restarting the machine, the cover is no longer glued. Recently, the author also received a book sent from Jiangxi, this is the case. This situation also occurs frequently.
(2) The stickers must be clipped during the travel to prevent the back of the book from tilting.
(3) The glue roller should be adjusted well. Too high, causing the glue layer to be too thin. If it is too low, the glue will not enter the slot, which may cause degumming.
(4) Be careful not to get dirty rubber rollers. Dirty rubber rollers (paper scraps, paper dust, etc.) can make the rubber rollers unevenly glued, which can easily cause a small amount of glue on some signatures.
(5) Strengthen the adjustment of the machine, even if it is a small problem, don't let it go, especially pay attention when making 80 grams of offset paper.
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