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不干胶印刷的时候出现白点怎么办?

来源:http://www.shengfengyinshua.com/ 日期:2019-12-07 发布人:admin   我们在不干胶印刷的时候,总会发现印刷的时候出现了白点,怎么都解决不好,接下来我就出现白点问题的原因和解决办法,详细的给大家介绍一下。总的来说,造成印刷白点问题的原因主要有以下四点:标签材料粗糙、材料掉粉、静电以及车间环境粉尘。本文将就上述四个方面的问题,分别给出解决方案。
不干胶标签印刷
  When we are printing with self-adhesive, we always find that there are white spots in the printing process, which can not be solved well. Next, I will introduce the causes and solutions of the problem in detail. Generally speaking, there are four main reasons for the problem of printing white spots: rough label materials, material powder, static electricity and workshop environment dust. This paper will give solutions to the above four problems.
  一 、材料表面粗糙造成的白点
  I. white spots caused by rough surface of materials
  目前在我国,不干胶标签的印刷主要以凸版和柔性版两种印刷方式为主。这两种印刷方式对不干胶材料的表面粗糙度要求都很高。例如铜版纸面材不干胶材料,如果采用胶印,其表面粗糙度(材料表面高低差异)小于1.4微米即可;但采用凸版和柔性版印刷时,其表面粗糙度需要小于0.7微米才能保证印刷过程中不出白点。这是因为后两种印刷方式的印刷压力要比胶印小得多,如果不干胶材料表面不够平滑就会造成部分材料表面印不上油墨,从而形成印刷白点,这种现象尤其容易出现在印刷大面积网点图文的过程中。在高倍放大镜下看,其特点是白点区域完全没有油墨。这是因为白点区域相对其他区域较低,印版上的油墨没有转移到材料表面。由于材料表面不够平滑导致的印刷白点,还有一个明显的特征,那就是白点往往是大面积的,多数情况下满版都是,非常明显。
  At present, in our country, the printing of self-adhesive label is mainly in letterpress and flexographic printing. These two printing methods require high surface roughness of self-adhesive materials. For example, if offset printing is used, the surface roughness (material surface height difference) of the self-adhesive material of copper plate paper can be less than 1.4 μ m; however, when letterpress and flexographic printing are used, the surface roughness needs to be less than 0.7 μ m to ensure no white spots in the printing process. This is because the printing pressure of the latter two printing methods is much smaller than that of offset printing. If the surface of self-adhesive material is not smooth enough, some materials will not be printed with ink, thus forming a printing white dot. This phenomenon is especially easy to appear in the process of printing large-area dot graphics. Under high magnification, the white dot area is completely free of ink. This is because the white spot area is lower than other areas, and the ink on the plate is not transferred to the material surface. There is also an obvious feature of the printing white spots caused by the lack of smoothness of the material surface, that is, the white spots are often large-area, and in most cases, the full page is very obvious.
  遇到这类印刷白点问题,我们可以通过以下方式来解决:
  In case of this kind of printing white dot problem, we can solve it by the following ways:
  1、更换合格的材料。不干胶材料表面不够平滑属于材料质量问题,我们可以要求材料供应商更换达标的材料来进行生产。
  1. Replace qualified materials. The surface of self-adhesive material is not smooth enough, which is a matter of material quality. We can ask the material supplier to replace the qualified material for production.
  2、但据笔者所知,在多数情况下,更换材料就无法保证工期,因为不干胶标签印刷企业的生产周期相当紧凑。况且印刷厂更换活件需要一系列的准备工作,一旦材料有问题不能印刷,那么准备工作就是白做,这对于印刷厂来说严重影响生产效率。如果遇到这种情况,我们可以考虑先在材料表面印刷一层底涂油或是冲淡剂(撤淡剂)。这两种印刷助剂基本上是无色的,不会对印刷品的颜色造成太大影响。印刷这两种助剂后材料表面会被填平,人为提高材料的平滑度,印刷白点现象会大大减少。
  2. As far as I know, in most cases, the replacement of materials cannot guarantee the construction period, because the production cycle of self-adhesive label printing enterprises is quite compact. In addition, a series of preparations are needed to replace the movable parts in the printing factory. Once there is a problem with the materials that can't be printed, the preparations are done in vain, which seriously affects the production efficiency of the printing factory. If this happens, we can consider printing a layer of primer or diluent on the surface of the material first. These two printing aids are basically colorless and will not have a great impact on the color of the printed matter. After printing these two additives, the surface of the material will be filled up. If the smoothness of the material is artificially improved, the phenomenon of printing white spots will be greatly reduced.
  二、材料掉粉造成的白点
  II. White spots caused by material falling
  材料掉粉也是造成不干胶标签印刷白点的常见原因之一。这种原因导致的印刷白点有一个显著特征,那就是刚开始印刷时白点比较轻微,但随着印刷时间的增加,白点会越来越多,同时在印刷设备上也能够明显看到有白色粉尘。这时候如果停机对印刷设备和印版进行清理,那么清理后白点会减少,可再印刷一段时间以后,白点和粉尘仍然不断增多,这是因为材料表面的粉尘会逐渐积累到印刷设备和印版上。由掉粉引起的印刷白点,在高倍放大镜下可以看到白点区域是有油墨的,但会有某些颜色的油墨没有印刷上,原因是在印刷该颜色时材料表面有粉尘脱落,从而导致油墨没印上。由掉粉所导致的印刷白点往往只会零星出现在印刷品表面,但会随着印刷时间的增加而增多。
  Material powder is also one of the common causes of white spots in label printing. The white dot caused by this reason has a significant feature, that is, the white dot is slight at the beginning of printing, but with the increase of printing time, the white dot will be more and more, and the white dust can be obviously seen on the printing equipment. At this time, if the printing equipment and plates are stopped for cleaning, the white spots will be reduced after cleaning. After printing for a period of time, the white spots and dust will continue to increase, because the dust on the material surface will gradually accumulate on the printing equipment and plates. For the printing white spots caused by powder dropping, ink can be seen in the white spot area under the high-power magnifying glass, but there will be some colors of ink that are not printed. The reason is that there is dust falling off on the surface of the material when printing the color, so the ink is not printed. The printing white spots caused by the powder dropping often only appear sporadically on the surface of the printed matter, but will increase with the increase of printing time.
  如果对这种现象进行细分,可以分为以下几种情况:
  If this phenomenon is subdivided, it can be divided into the following situations:
  1、面材掉粉
  1. Flour falling
  面材掉粉多发生于纸张类不干胶材料。因为多数纸张类材料在制造过程中都需要经过超压处理,以保障纸张更加紧密不容易掉粉。但如果超压过程控制不好,面材表面强度不够,就会出现在印刷过程中掉粉的情况。
  Surface material powder loss occurs in paper type self-adhesive materials. Because most of the paper materials need to be overpressured in the manufacturing process to ensure that the paper is more compact and not easy to lose powder. But if the overpressure process is not well controlled and the surface strength of the surface material is not enough, the powder will be dropped in the printing process.
  2、底纸掉粉
  2. The bottom paper is out of powder
  不干胶材料是一种复合材料,除了面材以外还有底纸。底纸一般有格拉辛、SCK、涂塑牛皮纸等几种。由于底纸也属于纸张,因此同样会出现掉粉的现象。同时,不干胶材料在制造过程中需要对底纸进行补水(回湿)处理,如果补水量过大,也会导致底纸的表面强度降低从而造成掉粉。
  Self adhesive material is a kind of composite material, in addition to the surface material, there is also the base paper. There are several kinds of backing paper, such as grazin, SCK, plastic coated kraft paper, etc. Because the backing paper also belongs to paper, so there will be the phenomenon of powder falling. At the same time, in the manufacturing process of self-adhesive material, it is necessary to make up water (rewetting) for the base paper. If the amount of water is too large, the surface strength of the base paper will also be reduced, resulting in powder loss.
  3、分切粉尘
  3. Cutting dust
  我们知道不干胶材料多数为卷到卷加工,因此供应商需要根据印刷厂的要求将大卷材料分切成不同宽度的小卷。在分切过程中,如果车间环境灰尘较多,就很容易导致材料表面落有粉尘;如果分切设备刀具比较钝,就有可能导致小卷材料两端落上粉尘。
  We know that most of the self-adhesive materials are roll to roll processing, so the supplier needs to divide the large roll materials into small rolls of different width according to the requirements of the printing factory. In the cutting process, if there is more dust in the workshop environment, it is easy to cause dust on the surface of the material; if the cutting tools of the cutting equipment are relatively blunt, it is likely to cause dust on both ends of the small coil material.
  那么,在实际生产中我们应如何判断是上述哪种掉粉导致的印刷白点?其实很简单,可以用3M810胶带分别对不干胶材料的面层和底纸进行测试。具体的测试方法是:先将不干胶材料面层与底纸表面的浮尘擦干净,再用胶带分别粘不干胶材料的面层和底纸。我们可以多粘几次,然后分别看面层和底纸上是否能粘下粉尘,哪一面能粘下粉尘,就是哪一面掉粉;如果两者都没有粘下明显的粉尘,那就是分切生产环境中的粉尘。
  So, in the actual production, how should we judge which of the above powdering causes the printing white spots? In fact, it is very simple to use 3m810 tape to test the surface layer and backing paper of self-adhesive material respectively. The specific test method is: first wipe the floating dust on the surface of the adhesive material and the bottom paper, and then stick the adhesive tape on the surface of the adhesive material and the bottom paper respectively. We can stick it several times, and then we can see whether the dust can be stuck on the surface layer and the bottom paper, which side can stick the dust, which is which side of the dust; if there is no obvious dust stuck on both sides, it is the dust in the slitting production environment.
  遇到这种情况,我们需要分别对待。譬如,如果是面材或者底纸自身掉粉导致的印刷白点,印刷企业很难解决,更好的办法就是更换合格的材料;如果是分切过程中的粉尘导致的印刷白点,那么可以考虑在印刷设备上加装除尘布或者除尘胶辊来解决。
  In this case, we need to treat them separately. For example, if it is the printing white spot caused by the surface material or the bottom paper's own powder falling, it is difficult for the printing enterprise to solve it. The best way is to replace the qualified material; if it is the printing white spot caused by the dust in the cutting process, it can be considered to add the dust removal cloth or the dust removal rubber roller on the printing equipment to solve it.
  4、油墨太粘
  4. The ink is too sticky
  有的时候油墨粘度太高也容易导致印刷白点。这是因为在印刷过程中油墨粘性太高会把材料表面的涂层粘掉,就如同用胶带去粘材料表面一样。这种现象多发生在凸版印刷纸张类面材不干胶材料上。我们知道纸张类材料具有一定的表面抗撕裂强度,但是在凸版印刷中,油墨是直接从印版转移到承印材料表面。同时凸版印刷采用的油墨为膏状,属于高粘油墨,因此在印刷过程中,印版在油墨的作用下会对承印材料表面形成一定的撕扯力。在这种力的作用下,一些纸张材料表面的涂层可能会脱落。
  Sometimes ink viscosity is too high also easy to cause printing white spots. This is because in the printing process, too high ink viscosity will stick off the coating on the material surface, just like using tape to stick on the material surface. This kind of phenomenon often occurs on the surface material of letterpress paper. We know that paper materials have certain surface tear strength, but in letterpress printing, ink is directly transferred from the plate to the substrate surface. At the same time, the ink used in letterpress printing is paste, which belongs to high viscosity ink. Therefore, in the printing process, the printing plate will form a certain tearing force on the surface of the substrate under the effect of ink. Under the action of this force, the coating on the surface of some paper materials may fall off.
  由此情况导致的印刷白点,一般有一定的规律性和周期性,且印刷品上的白点不会太多。因为印版将不干胶材料表面的涂层粘下来后,有时候会留在印版上,因此在后面的几个印刷周期内,印刷品上同样的位置也会有相同形状的白点。
  The printing white spots caused by this situation generally have certain regularity and periodicity, and there are not too many white spots on the printed matter. Because the plate will stick the coating on the surface of the adhesive material, sometimes it will stay on the plate, so in the following several printing cycles, the same position on the printed matter will also have the same shape of white spots.
  遇到此类问题,可以尝试降低油墨的粘度。降低油墨粘度的方法有很多,例如在油墨中加入调墨油、减粘剂等助剂。这里要说明的是助剂的添加都有一定的比例,一般在5%—10%,因为加得太多会使油墨变得过于稀释从而影响到印刷效果。同时,也可尝试“深墨薄印”法,即在墨斗中将油墨打薄,并通过加大墨斗辊转动速度的方式来保证油墨供给。这样做的好处是在墨斗辊转动搅拌过程中会使油墨稀释。因为高粘油墨具有触变性,即在经过一段时间搅拌后油墨的粘性会下降。当然,也可以利用油墨的这种特性来解决油墨过粘的问题。
  Encounter such problems, you can try to reduce the viscosity of the ink. There are many ways to reduce the viscosity of ink, such as adding inking oil, viscosity reducer and other additives to the ink. It should be noted that there is a certain proportion of additives, generally 5% - 10%, because too much additives will make the ink become too diluted and affect the printing effect. At the same time, we can also try the "deep ink thin printing" method, that is, to thin the ink in the ink bucket, and to ensure the ink supply by increasing the rotation speed of the ink bucket roller. The advantage of this is that the ink will be diluted during the mixing process of the ink bucket roll rotation. Because the high viscosity ink has thixotropy, that is, after a period of time mixing, the viscosity of the ink will decrease. Of course, the ink can also be used to solve this problem.
  此类问题是所有问题中更好判断并且也更容易解决。首先印刷车间一定要干净、整洁,如果车间卫生环境不好就不能印刷,尤其是在印刷大面积网点或者实地的活件时,对车间的环境清洁度要求就更高。这种印刷白点,只要注意车间卫生就能够解决。
  This kind of problem is the best judgment and the easiest to solve. First of all, the printing workshop must be clean and tidy. If the sanitary environment of the workshop is not good, it can not be printed, especially when printing large-area outlets or live parts on the spot, the environmental cleanliness requirements of the workshop will be higher. This kind of printing white spot can be solved only by paying attention to workshop sanitation.

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