白點(diǎn)氣泡：①干燥不充分

White spot bubbles: ① Insufficient drying

②上膠量不足：督辦、復(fù)溶性差、轉(zhuǎn)移率下降。。  薄膜太厚

② Insufficient glue application: poor supervision, poor solubility, and decreased transfer rate.. Thin film too thick

③復(fù)合后膠未流平：膠分子量大、熟化不夠，復(fù)合熱輥溫度太低、氣溫較低而預(yù)熱輥沒用

③ After compounding, the glue is not leveled: the molecular weight of the glue is large, the aging is not enough, the temperature of the compounding hot roller is too low, and the temperature is too low, making the preheating roller useless

一、鍍鋁膜復(fù)合印刷基材，如產(chǎn)生氣泡，在印刷膜淺色部分看起來是白點(diǎn)。氣泡部分兩層基材未密切貼合，不一定是圓鼓鼓地凸起狀。但嚴(yán)重的干燥不良形成的氣泡倒是鼓起的，大的像芝麻粒。產(chǎn)生這類氣泡的原因有的是膠黏劑未干透，有的是油墨溶劑干燥不充分造成，經(jīng)常出現(xiàn)在大面積跌印部分。某些小印刷機(jī)還在使用紅外線干燥箱。輕微的干燥不良雖然沒有鼓起大氣泡，只足夠小事，能透過某些薄膜釋放溶劑。如同樣的工藝條件，PET復(fù)鋁箔有氣泡，而BOPP復(fù)鋁箔熱化后氣泡會(huì)消失。

1、 Aluminum coated composite printing substrate, if bubbles are generated, appears as white dots in the light colored part of the printing film. The two layers of substrate in the bubble part are not closely attached, and may not be bulging. But the bubbles formed by severe poor drying are bulging, large like sesame seeds. Some of the reasons for producing such bubbles are due to incomplete drying of the adhesive, while others are due to insufficient drying of the ink solvent, often appearing in large areas of drop printing. Some small printing machines still use infrared drying boxes. Mild dryness, although not accompanied by large bubbles, is only minor enough to release solvents through certain thin films. Under the same process conditions, PET composite aluminum foil has bubbles, while BOPP composite aluminum foil will disappear after heating.

二、干燥不良形成的小氣泡和上膠量不足產(chǎn)生的氣泡用放大鏡觀察區(qū)別不大，這時(shí)需要作理性分析。任何看起來很光滑的表面，用放大鏡觀察都是凹凸不平的。膠黏劑把表面抹平需要一定厚度——也就是上膠量。普通透明復(fù)合膜用低粘度膠黏劑。印刷膜涂膠要厚點(diǎn)，如白膜，色塊下托白膜厚度就更大。里印復(fù)合墨樹脂含量少于表印白膜，所以復(fù)合白墨表面比較粗糙。粗糙苯類是復(fù)合白墨的優(yōu)點(diǎn)，有利于膠黏劑滲透產(chǎn)生足夠的剝離強(qiáng)度，反過來卻需要較多的上膠量。為了保證油墨部分有足夠的膠黏劑厚度，上膠量需3-3.5G，少于這標(biāo)準(zhǔn)也是上膠量不足。因堵版造成上膠量不足容易理解。堵版分2種：一時(shí)突發(fā)性的，因涂料復(fù)溶性差和操作中轉(zhuǎn)移率不斷下降造成。這類堵版如未找出原因及時(shí)排除，僅靠停車擦版只能維持一時(shí)。另一種堵版是漸變型的，嚴(yán)格地說不能算故障，因?yàn)槊看螐?fù)合后不可能把網(wǎng)紋輥中的殘膠完全清洗干凈，殘膠日復(fù)一日地在網(wǎng)孔底部沉積固化。上膠量慢慢變小、小氣泡也漸漸產(chǎn)生、由少變多、由小變大。終因某做要求高的產(chǎn)品和復(fù)合較厚的膜，小氣泡變得不可容忍。這時(shí)要用專門的洗版液。問題是解決了，卻不是一種好的生產(chǎn)習(xí)慣，因?yàn)橹坝写罅拷橛诤细衽c不合格之間的產(chǎn)品被生產(chǎn)出來。我們提倡定期測(cè)量上膠量，當(dāng)上膠量遞減預(yù)定值時(shí)就清洗。

2、 There is not much difference between the small bubbles formed by poor drying and the bubbles generated by insufficient glue application when observed with a magnifying glass. Therefore, rational analysis is necessary. Any surface that looks very smooth is uneven when viewed with a magnifying glass. The adhesive needs a certain thickness to smooth the surface - that is, the amount of adhesive applied. Low viscosity adhesive for ordinary transparent composite films. Printing film coating should be thicker, such as white film, and the thickness of the white film under the color block is even greater. The resin content of inner printed composite ink is less than that of surface printed white film, so the surface of composite white ink is relatively rough. Rough benzene is an advantage of composite white ink, which is beneficial for the penetration of adhesive to produce sufficient peel strength, but in turn requires a higher amount of adhesive application. In order to ensure sufficient adhesive thickness for the ink part, the adhesive amount needs to be 3-3.5G, which is also insufficient. It is easy to understand that insufficient glue application is caused by blocking the plate. There are two types of blocking: temporary and sudden, caused by poor paint re solubility and continuous decrease in transfer rate during operation. If the cause of this type of blockage is not identified and eliminated in a timely manner, relying solely on parking and wiping the plate can only maintain it for a while. Another type of blocking is a gradient type, strictly speaking, it cannot be considered a malfunction because it is impossible to completely clean the residual glue in the anilox roller after each composite, and the residual glue accumulates and solidifies at the bottom of the mesh hole day after day. The amount of glue gradually decreases, and small bubbles gradually emerge, increasing from less to more, and from small to large. Eventually, due to the production of demanding products and thick composite films one day, small bubbles became intolerable. At this point, a specialized plate washing solution needs to be used. The problem is solved, but it is not a good production habit because a large number of products were previously produced between qualified and unqualified. We advocate regularly measuring the amount of glue applied and cleaning when the amount of glue decreases to a predetermined value.

三、有時(shí)候干燥很充分，上膠量也不少，剛下機(jī)的復(fù)合膜還是有氣泡。其實(shí)剛復(fù)合好的產(chǎn)品沒有一點(diǎn)氣泡是不太可能的。小的氣泡經(jīng)過熟化能，因?yàn)椴缓軇┑珱]喲充分固化的聚氨酯膠黏劑有一定的流動(dòng)性。溫度越高流動(dòng)越大，分子量越大流動(dòng)性越小，固化的實(shí)質(zhì)就是分子量不斷增大的過程。熟化室中的復(fù)合膜，膠黏劑在溫度的作用下緩慢流平，大氣泡縮小，小氣泡消失，直膠黏劑的分子量增大到膠不能流動(dòng)為止。有經(jīng)驗(yàn)的操作工看得出多大的白點(diǎn)能消失，如沒有把握先把樣品放進(jìn)80度烘箱中30分鐘，檢查氣泡是否去除。同樣大小的氣泡，低粘度的膠能，而高粘度膠可能不行，這是因?yàn)?0%高粘度膠分子量大，流平性差。

3、 Sometimes the drying is sufficient, and the amount of glue applied is also considerable. The composite film just removed from the machine still has bubbles. In fact, it is impossible for a newly compounded product to have no bubbles at all. Small bubbles can be eliminated by aging, as polyurethane adhesives that do not contain solvents but do not fully cure have a certain degree of fluidity. The higher the temperature, the greater the flow, the larger the molecular weight, and the smaller the fluidity. The essence of solidification is the process of continuously increasing molecular weight. The composite film in the curing chamber is slowly flattened by the adhesive under the action of temperature, with large bubbles shrinking and small bubbles disappearing until the molecular weight of the adhesive increases to the point where the adhesive cannot flow. Experienced operators can see how large white spots can disappear. If unsure, it is best to first place the sample in an 80 degree oven for 30 minutes and check if bubbles are removed. Bubbles of the same size can be eliminated with low viscosity glue, while high viscosity glue may not be effective because 50% of high viscosity glue has a large molecular weight and poor leveling performance.