一、紙張?zhí)匦詫?duì)印刷品光澤的影響
1、 Influence of paper characteristics on the gloss of printed matter
在印刷過程中，墨膜轉(zhuǎn)移到紙張表面，并填充了紙面的凹凸不平，使印刷品表面相當(dāng)平滑。印刷品墨膜表面對(duì)光的鏡面反射決定著印刷品光澤的大小，而墨膜表面又同紙張?zhí)匦悦芮邢嚓P(guān)。
In the printing process, the ink film is transferred to the paper surface and filled with the uneven surface of the paper, making the surface of the printed matter quite smooth. The specular reflection of light on the ink film surface of printed matter determines the gloss of printed matter, and the ink film surface is closely related to the characteristics of paper.
墨膜厚度是影響印刷品光澤的主要因素。在紙張更大限度吸收油墨的連結(jié)料以后，剩余的連結(jié)料仍保留在墨膜中，它可以有效地提高印刷品的光澤。墨膜越厚，剩余的連結(jié)料越多，越有利于提高印刷品的光澤。研究發(fā)現(xiàn)：光澤隨墨膜厚度提高的趨勢(shì)，因不同的紙張而有所不同。圖1為相同油墨在四種不同紙張上印刷所得印刷品光澤與墨膜厚度的關(guān)系曲線。從圖上可見，盡管油墨相同，但不同紙張所形成的印刷品光澤隨墨膜厚度而變化的趨勢(shì)是不同的。高光澤涂料紙?jiān)谀ぽ^薄時(shí)，其印刷品光澤隨墨膜厚度的增加而降低，這是由于墨膜掩蓋了紙張本身原有的較高的光澤，而墨膜本身形成的光澤又由于紙張吸收而降低。隨著墨膜厚度的增加，紙張本身原有的較高的光澤就越難透過墨膜反映出來。當(dāng)墨膜厚度達(dá)到1.5μm時(shí)，紙張對(duì)連結(jié)料的吸收基本飽和。之后，隨著墨膜厚度的繼續(xù)增加，保留連結(jié)料越多，光澤也就不斷提高。涂料紙板印刷品在墨膜較薄時(shí)光澤隨墨膜厚度的增加迅速提高，在墨膜厚度增加到3.8μm以后，光澤便不再隨墨膜厚度的增加而提高。但是無論何種紙張，光澤隨墨膜厚度增加而提高的量都應(yīng)有一定的限度。
Ink film thickness is the main factor affecting the gloss of printed matter. After the paper absorbs the binder of the ink to a greater extent, the remaining binder is still retained in the ink film, which can effectively improve the luster of the printed matter. The thicker the ink film, the more remaining binder, which is more conducive to improving the luster of the printed matter. It is found that the trend of gloss increasing with ink film thickness varies with different paper. Figure 1 shows the relationship between the gloss of printed matter printed with the same ink on four different papers and the thickness of ink film. It can be seen from the figure that although the inks are the same, the variation trend of print gloss formed by different papers with ink film thickness is different. When the ink film of high gloss coating paper is thin, the print gloss decreases with the increase of the ink film thickness, because the ink film masks the original high gloss of the paper itself, and the gloss formed by the ink film itself decreases due to the absorption of the paper. With the increase of ink film thickness, the original high gloss of the paper itself is more difficult to be reflected through the ink film. When the ink film thickness reaches 1.5 μ M, the absorption of paper to binder is basically saturated. Then, as the thickness of the ink film continues to increase, the more binder is retained, and the luster will continue to improve. When the ink film of Coated Paperboard Printing is thin, the gloss increases rapidly with the increase of ink film thickness, and the ink film thickness increases to 3.8 μ M later, the gloss no longer increases with the increase of ink film thickness. However, no matter what kind of paper, the gloss should be improved with the increase of ink film thickness.
紙張?zhí)匦詫?duì)印刷品光澤的影響
Influence of paper characteristics on the gloss of printed matter
紙張由于纖維交織而形成毛細(xì)管網(wǎng)絡(luò)結(jié)構(gòu)，具有大量孔隙，成為吸收油墨的基礎(chǔ)。紙張毛細(xì)管網(wǎng)絡(luò)對(duì)油墨連結(jié)料的吸收時(shí)間和連結(jié)料固著時(shí)間之間的平衡決定著印刷品光澤形成時(shí)連結(jié)料滲透的程度。一般印刷品光澤均隨紙張吸收能力的增強(qiáng)而降低。
Paper forms capillary network structure due to fiber interweaving, which has a large number of pores and becomes the basis of absorbing ink. The balance between the absorption time of ink binder by paper capillary network and the fixing time of binder determines the degree of binder penetration during the formation of printing gloss. Generally, the gloss of printed matter decreases with the enhancement of paper absorption capacity.
紙張平滑度及本身光澤影響印刷品光澤。平滑度高有利于形成均勻平滑的墨膜，從而提高印刷品光澤。紙張本身的光澤好則能提高墨膜的反射率，尤其對(duì)于透明油墨更是如此。兩種油墨印刷在4種光澤不同的涂料紙上的結(jié)果。從圖可見，兩種油墨的印刷品光澤均隨紙張本身光澤的提高而提高。印刷品光澤與紙張本身光澤之間的相關(guān)性比印刷品光澤與紙張吸收能力之間的相關(guān)性還強(qiáng)。
The smoothness of paper and its own gloss affect the gloss of printed matter. High smoothness is conducive to the formation of uniform and smooth ink film, so as to improve the gloss of printed matter. Good gloss of the paper itself can improve the reflectivity of the ink film, especially for transparent ink. The results of printing two inks on four kinds of coated paper with different gloss. It can be seen from the figure that the print gloss of the two inks increases with the improvement of the gloss of the paper itself. The correlation between print gloss and paper gloss is stronger than that between print gloss and paper absorption capacity.
從上面的討論中可以發(fā)現(xiàn)，紙張平滑度、光澤和吸收能力之間也存在著相關(guān)性。從造紙過程很容易解釋這一點(diǎn)。例如，壓光處理能改進(jìn)紙張平滑度和光澤，同時(shí)也減少紙張的孔隙量，從而降低紙張的吸收能力。此外，紙張表面的pH值也是印刷品光澤形成的一個(gè)不可忽視的因素，ph值高，有利于油墨干燥，因而有利于提高印刷品的光澤。
From the above discussion, it can be found that there is also a correlation between paper smoothness, gloss and absorption capacity. It is easy to explain this from the papermaking process. For example, calendering can improve the smoothness and luster of the paper, but also reduce the porosity of the paper, thus reducing the absorption capacity of the paper. In addition, the pH value of the paper surface is also a factor that can not be ignored in the formation of print gloss. High pH value is conducive to ink drying, so it is conducive to improve the gloss of print.
二、紙張?zhí)匦詫?duì)印刷圖像階調(diào)再現(xiàn)的影響
2、 Influence of paper characteristics on tone reproduction of printed image
理想階調(diào)再現(xiàn)是獲得高質(zhì)量印刷圖像重要的工藝環(huán)節(jié)，大多數(shù)不良印刷品都是由于階調(diào)再現(xiàn)方面的問題造成的。
Ideal tone reproduction is an important process to obtain high-quality printed images. Most bad prints are caused by the problems of tone reproduction.
圖像復(fù)制首要的要求是被復(fù)制的圖像在視覺上跟原稿匹配。但事實(shí)上大多數(shù)情況下是不可能實(shí)現(xiàn)的。表1列出了不同類型紙張復(fù)制圖象的密度范圍，而原稿的密度范圍在0~2.7（3.0）。顯然在大多數(shù)情況下，原稿的密度范圍比印刷圖像的密度范圍大，而且隨著紙張質(zhì)量的降低，可復(fù)制的密度范圍越小，對(duì)于飽和度和色彩來說也是如此。
The primary requirement of image reproduction is that the copied image visually matches the original. But in fact, it is impossible in most cases. Table 1 lists the density range of copied images on different types of paper, while the density range of originals is 0 ~ 2.7 (3.0). Obviously, in most cases, the density range of the original is larger than that of the printed image, and with the decrease of paper quality, the smaller the reproducible density range, as well as for saturation and color.
解決的方法是壓縮原稿的階調(diào)范圍，使其和紙張等能夠再現(xiàn)的密度范圍相匹配。
The solution is to compress the gradient range of the original to match the density range that can be reproduced by paper, etc.
三、紙張?zhí)匦詫?duì)網(wǎng)點(diǎn)加大量的影響
3、 Influence of paper characteristics on dot gain
1. 網(wǎng)點(diǎn)加大
1. Increased outlets
網(wǎng)點(diǎn)加大對(duì)復(fù)制色相變化的影響比任何其它變量都大。在紙張上印刷的墨量會(huì)影響網(wǎng)點(diǎn)加大，而網(wǎng)點(diǎn)加大則影響印刷反差。在印刷黑白或彩***目調(diào)圖像時(shí)，網(wǎng)點(diǎn)加大會(huì)改變畫面反差并引起圖像細(xì)節(jié)與清晰度的損失。在多色印刷中，網(wǎng)點(diǎn)加大會(huì)導(dǎo)致反差丟失、圖像深暗、網(wǎng)點(diǎn)糊死并引起急劇的色彩變化。
The effect of dot enlargement on the change of reproduction hue is greater than any other variable. The amount of ink printed on the paper will affect the dot increase, and the dot increase will affect the printing contrast. When printing black-and-white or color * * * eye tone images, dot addition will change the picture contrast and cause the loss of image detail and clarity. In multicolor printing, dot enlargement will lead to loss of contrast, dark image, dot paste and sharp color change.
紙張?zhí)匦詫?duì)網(wǎng)點(diǎn)加大量的影響
Influence of paper characteristics on dot gain
油墨的光滑表面在較高質(zhì)量的紙上產(chǎn)生了佳的實(shí)地密度，當(dāng)紙張質(zhì)量降低時(shí)，實(shí)地油墨密度降低，產(chǎn)生一定的網(wǎng)點(diǎn)擴(kuò)大，影響了印刷品的質(zhì)量。
The smooth surface of ink produces a good field density on high-quality paper. When the paper quality is reduced, the field ink density is reduced, resulting in a certain dot expansion, which affects the quality of printed matter.
網(wǎng)線數(shù)越高，網(wǎng)點(diǎn)直徑越小，紙面上微小的凹坑也能歪曲或遺漏細(xì)小的印版網(wǎng)點(diǎn)。因此，網(wǎng)線數(shù)越高的精細(xì)印品，要求紙張平滑度越高。這是選用紙張的一個(gè)原則。但是實(shí)際工作中，也可以適當(dāng)調(diào)節(jié)油墨的某些性能或改變工藝參數(shù)來適應(yīng)紙張的這一特性。
The higher the number of wires, the smaller the dot diameter, and the small pits on the paper can also distort or omit small printing plate dots. Therefore, the higher the number of screen lines, the higher the smoothness of the paper. This is a principle of paper selection. However, in practice, some properties of ink can also be adjusted appropriately or process parameters can be changed to adapt to this characteristic of paper.
四、紙張?zhí)匦詫?duì)印刷品套印精度的影響
4、 Influence of paper characteristics on overprint accuracy of printed matter
對(duì)于精細(xì)的印刷品，套準(zhǔn)要求較高，一般允許誤差在0.05mm內(nèi)。多色印刷中，引起套印不準(zhǔn)的原因很多，但印刷過程中紙張因含水量變化而產(chǎn)生的紙張變形是一個(gè)重要因素。
For fine prints, the registration requirements are high, and the general allowable error is within 0.05mm. In multicolor printing, there are many reasons for inaccurate overprint, but the paper deformation caused by the change of water content in the printing process is an important factor.
眾所周知，紙張含水量改變不僅導(dǎo)致紙張的膨脹或收縮，而且由于含水量變化使得紙張局部尺寸變化，從而產(chǎn)生其它形式的變形，如卷曲、皺摺等。這種變形嚴(yán)重地影響印刷品的印刷工作者關(guān)心的是相對(duì)濕度對(duì)紙張含水量的影響
As we all know, the change of water content of paper not only leads to the expansion or contraction of paper, but also changes the local size of paper due to the change of water content, resulting in other forms of deformation, such as curling, folding and so on. This deformation seriously affects the quality of printed matter. The printer is concerned about the influence of relative humidity on the water content of paper
① 室溫一定，高濕度時(shí)相對(duì)濕度變化引起含水量的變化率比中濕度時(shí)相對(duì)濕度變化引起含水量的變化率大得多；低濕度時(shí)也是如此。從這一角度看，印刷在中等濕度條件下進(jìn)行有利
① At a certain room temperature, the change rate of water content caused by the change of relative humidity at high humidity is much greater than that caused by the change of relative humidity at medium humidity; The same is true at low humidity. From this point of view, printing is advantageous under medium humidity conditions
② 兩者組成一個(gè)閉合的滯后回路，這種現(xiàn)象稱為紙張的調(diào)濕滯后現(xiàn)象。表現(xiàn)為：某一相對(duì)濕度條件下達(dá)到平衡水量的紙張，如果再經(jīng)吸濕（脫濕）后，重新回到原有相對(duì)濕的環(huán)境空氣中，其含水量比原來的要有所增加（減少）。
② The two form a closed hysteresis loop, which is called the humidity regulation hysteresis of paper. The performance is as follows: if the paper that reaches the equilibrium water content under a certain relative humidity condition returns to the original relatively wet ambient air after moisture absorption (dehumidification), its water content will increase (decrease) compared with the original.
為了使紙張的含水量在整個(gè)紙面上保持均勻一致，并且與印刷車間的溫濕度相適應(yīng)；同時(shí)為了使紙張對(duì)環(huán)境濕度的敏感程度有所降低，提高紙張尺寸的穩(wěn)定性，一般在印刷之前，要進(jìn)行調(diào)濕（吊晾）處理。
In order to keep the moisture content of the paper uniform on the whole paper surface and adapt to the temperature and humidity of the printing workshop; At the same time, in order to reduce the sensitivity of paper to environmental humidity and improve the stability of paper size, humidity regulation (hanging) treatment is generally carried out before printing.
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