Quality problems that appear in the book pages after book binding are widespread in printing plants across the country, and now continue to be a difficult problem in processing and binding, which is detrimental to the overall quality of the book. In recent years, the reflection has been more serious. Many studies have been made to create favorable conditions, but so far it has not been solved well due to various reasons. Let's talk about the causes and solutions of the folds and hilly folds on the pages of the book after binding.
1. The effect of humidity on sheet folds
The paper contains a certain amount of moisture, which makes the paper flexible and peaceful. The approximate moisture content of 7% is reasonable. If this amount is exceeded, the paper may become brittle, moist or deformed. Now the quality of books and papers is getting better and better, and the grammage is getting higher and higher. If the production workshop does not pay attention to the specification of humidity, it will cause serious losses. At present, there are hundreds of thousands of bookbinding factories in the country, and the conditions are good (about 1/10 of the total) can also guarantee the temperature and relative humidity of the production workshop, and the poor conditions can not be guaranteed. Some processing plants also pay attention to scientific management, stacking book pages, signatures and semi-finished book blocks, etc., some are stacked against the wall, some are stacked on the ground (without paper table), and some are placed near the heater. Once these paper products are wet or dried, the reasonable moisture inside the paper is destroyed, and the pages are hydrocarbon-shaped. The page sent to the Lord was flat and flat. After the phase, the whole book core appeared hilly wrinkles, and the publisher was very dissatisfied with it. These are all caused by management problems, so management personnel must take it seriously, strengthen scientific process management, rearrange the site facilities and rational layout, ensure reasonable temperature and relative humidity in the workshop, and prevent book paper from being damaged.
2. There are too many page folds when designing typesetting or imposition
When the pages are folded, the more the number of folds, the greater the error, and the greater the number of overlaps, the greater the possibility of wrinkles. This is because the air in the overlapped signatures cannot be released, causing wrinkles. . For a long time, it has been stipulated that up to four folds should be broken and air must be broken. However, the weight of book block paper used in the past is generally about 52g / m2 of relief paper or newsprint, but now the book block paper is mainly about 65g / m2 offset paper or 80g / m2 coated paper. The weight of the book block paper is increased, and the thickness is increased. If you still use the thin paper to make the four-fold or three-fold, there will of course be problems. At this point, the design departments of publishing houses and printing houses must draw attention to them. They can no longer follow the old regulations and do not think that the number of folds saves labor. In fact, this does not take into account the quality of the processed products. Because there is no output without quality, the relationship between quantity and quality must be clarified. This will never change.
According to these circumstances and the reality of increased paper weight, the revised national industry standard CY / T27ï¼1999.3, 3.1.2 clearly stipulates that: papers under 59g / m2 can be folded up to fourfold; papers from 60g / m2 to 80g / m2 Fold in three folds; papers over 81g / m2 can be folded up to two folds. The stipulations ensure that no wrinkles will appear in the pages after book binding. However, according to the understanding of printing factories across the country, many units have not paid attention to this problem so far, and some have blindly pursued output and did not implement national industry standards. As a result, the book has many wrinkles, dead folds, and products that are not bound. The serious consequences of qualifying.
3. The machine folding is not equipped with a rip knife
The folding roller of the current folding machine is equipped with a crease cutting device for book signature creases. This type of rupture knife device cuts the dead seam of the signature into regular patterns through the transmission of pages and the transmission of the folding roller. The small mouth of the book, in order to expel the air in the signature, to prevent the dead folds caused by the pressure after the book is processed. However, it is understood that in a large part of the factories with folding machines in the country, when using the folding machine, because of the fear that the slitting knife is not accurate (it can not be accurately drawn on the crease line), the tearing knife device is unloaded Don't use it, this is extremely undesirable. The inaccuracy of nicking is the technical problem of adjusting and mastering the folding machine. It is impossible to dismantle the nicking device at will because of the failure of the technology. As a result, all the signatures inevitably appear wrinkled. This phenomenon of the technology, otherwise can not guarantee the product quality of the unit.
At present, the commonly used H660 folio four-fold grid knife hybrid folding machine, if there is no break device on the third fold (the folio is four-fold), it should be modified to solve the problem that the four-fold signature is not broken. A wrinkled quality problem occurs.
4. Manual folding is not broken
3.1.1 of CY / T27ï¼1999.3 also stipulates that: three folds (referring to paper of 6g / m2 or more) and signatures of more than three folds shall be cut out to exclude air. This article is also to ensure that the signature does not crease after folding. Manually folded four folds (50g / m2 and below paper) or manually folded three folds (60g / m2 ~ 80g / m2 paper) should be broken in the penultimate folding fold of the signature to exclude the signature There is air inside to prevent wrinkles from appearing, but many units now know that they should be broken when folding manually, but blindly pursuing output is not to break, and the final wrinkles after book binding are extremely serious and cannot be remedied. This approach is extremely undesirable. The factory should implement the national standard seriously and cannot be ignored.
5. The impact of improper processing
In addition to the above reasons, it is also important whether the process is reasonable. Binding books or books is inseparable from adhesives. Nowadays, binding adhesives are more water-soluble. These adhesives contain a lot of water, especially cold glue, almost all are water-soluble. On paper, it has a certain effect on paper. Some pages are wrinkled and deformed as soon as they are glued, so the viscosity of the glue must be reasonable and appropriate. Some factories use adhesives that are not sufficiently viscous, and use more dosage to make up for it, causing too much water in the pages to deform the paper and wrinkles. In general, the adhesive used should keep the viscosity at the most suitable lower limit, and the dosage is based on less and even, so as to ensure that the book is firmly bonded, and the book pages are not immersed in water to ensure the flatness of the book. You should also pay attention to which kind of adhesive is used, and there are some inappropriate ones. Because there are many types of adhesives nowadays, some are suitable and some are not. The selection must be based on the texture of the adherend and the required viscosity and other requirements.
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