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Copper paper and copper card (Part 2)

for some copper card, due to the use of new chemical raw materials and high-quality pulp, it can be close to the whiteness and gloss of copper paper. However, compared with coated paper, these indicators can only be close and cannot be exceeded. This is because each performance index of paper is interrelated. Usually, in order to obtain some performance, other performance must be sacrificed. Copper plate card must first ensure a high loose thickness and stiffness, but in this way, it is impossible to have a high coating amount and high pressure. At this time, to improve the gloss, the more effective way is to increase the amount of porcelain clay in the paint. However, the problem is that the increase in the amount of porcelain clay can easily lead to problems such as coating scratches, and the color of the paper is also yellow. In order to achieve high whiteness, a large number of fluorescent brighteners must be added. However, fluorescent brighteners will have a potential impact on people, and there is also a certain limit to the improvement of whiteness. Therefore, the gloss and whiteness of coated card can only be close to coated paper at most. According to our research, the whiteness of copper plate card can only reach 92~94 degrees at most, and the gloss can only reach about 72 degrees at most. It is very difficult to exceed it again. In addition, according to our tests, none of the high whiteness copper plate cards contain a large amount of fluorescent brighteners, which is a potential threat to the human body

the low coating amount and pressure of copper plate cards lead to relatively high surface roughness

the requirements for loose thickness and stiffness of coated paper are not as high as those of paperboard. Therefore, in production, high coating amount and high whiteness raw materials can be used, and the gloss, whiteness and surface smoothness can be easily obtained through the super calendering of high chemical giant one disassembly, three temperature and high pressure. Of course, the loose thickness and stiffness are lower than that of white card. If customers need it, we can make the gloss of the paper reach 75~80 degrees and the whiteness reach more than 95 degrees by improving the formula and production process

Table 2 shows the differences in whiteness, gloss, loose thickness and stiffness between the coated card with the highest whiteness and gloss in China and ordinary high-end Coated paper. It should be pointed out that the indicators of coated paper in the table are not the highest level of domestic high-end Coated paper, and paperboard is the best level we can find in China at present (so far, we have only found that one brand of white card can reach this indicator). The data in the table shows that the maximum whiteness of domestic coated cards is slightly lower than the normal level of coated paper, while the fluorescent whiteness exceeds 80% of coated paper. The glossiness of the coated card is also lower than that of coated paper, and the roughness of PPS is higher than that of coated paper. For other domestic high-grade copperplate cards, the whiteness is generally 85~90 degrees, the gloss is generally 60 degrees, and the PPS roughness is slightly higher than that of the copperplate cards listed in the table (about 1.2~1.5 μ m)。 These indicators are significantly inferior to coated paper. Of course, the stiffness and loose thickness of these cardboard are higher than that of coated paper

(3) differences in durability

for coated paper and coated card, due to the different raw materials used, in addition to the performance differences mentioned above, there are also certain differences in the durability of paper

after long-term storage of paper, due to changes in the structure of paper fibers and chemicals in the paper, there will be problems such as the safety belt used in the paper white power industry is placed higher than the operator to fall, or the personal protective equipment that will safely hang the operator after the fall is reduced, yellowed, and reduced strength. Coated paper may need to be preserved for a long time due to its main compositional use, so the durability of paper is an important assessment factor in our formulation design. In order to reduce the yellowing and aging of paper, we choose high-quality bleached wood pulp with good aging resistance, and other chemicals have good durability. In order to obtain loose thickness, stiffness and other properties, the core layer of copper card must use ground wood pulp. Usually, in order to reduce the cost, straw pulp, waste pulp and other pulp with poor quality must be added. In addition, in order to increase the strength and stiffness, a large number of chemical products will be added to the core layer to vigorously develop new materials. These pulps and chemicals will have obvious strength decline and yellowing after being exposed to light or over time, which is not conducive to long-term preservation. If you want to use coated cards as cultural paper for books, magazines, etc., you'd better make a full assessment of this problem in advance

we have carried out relevant aging experiments on high-grade coated cards and high-grade coated paper containing fully bleached chemical pulp in the market (according to the standard: TAPPI T453). In the experiment, we tear the two kinds of paper from the middle, place them in a ventilated oven at 105 ℃, and measure the whiteness of the surface and middle of the paper every 24 hours. This experiment actually simulates the aging process of paper in the natural environment through the high temperature of the oven

at the beginning of the experiment, the whiteness of the two kinds of paper did not differ significantly when baking was not carried out. After baking for 24 hours, the original whiteness difference is small, but there is a difference of about 6 degrees. At this time, the whiteness difference between paper and card can be clearly distinguished with the naked eye. With the extension of testing time, this whiteness difference has maintained and gradually expanded in recent years, with the rapid growth of consumption and the continuous expansion of the scope of utilization. This shows that coated cards are more prone to aging problems than paper, which is not conducive to long-term storage

(4) other precautions for use

as mentioned above, coated cards are traditionally used in the packaging industry, while coated paper is traditionally used in culture. Coated paper has high whiteness, gloss, smoothness and durability, while coated card has high loose thickness and stiffness. As a manufacturer of coated paper, we also recommend customers to use it according to this classification. Of course, customers have the right to choose coated paper or coated card according to their own requirements instead of the above classification. No matter what choice customers make, we suggest that customers should pay attention to the following aspects in addition to the card and paper differences mentioned above when making decisions:

thickness and stiffness are not clearly required in the existing national standard for coated paper (GB/t10335), and most coated paper manufacturers do not strictly control them. Therefore, if the customer has high requirements for the loose thickness and stiffness of the paper, it should be considered to choose paper jam. Otherwise, once there is a problem in thickness and stiffness, because there are no specific requirements in the national standard of coated paper, users may fall into a dilemma when negotiating with coated paper manufacturers. Similarly, for paperboard, the existing three industry standards (qb/t 1011 single-sided coated paperboard, QB/T2250 single-sided paperboard and QB/t3523 white paperboard) do not specify gloss, and the requirements for whiteness and smoothness are also very low. Therefore, if customers need the performance of these two aspects, it is better to choose coated paper, otherwise similar problems will occur

many domestic users want the paper to be thick and straight. From this point of view, it seems that copper card has more advantages. However, in many cases, it may not be appropriate to use thick and straight copper plate cards. For example, if you use a coated card to make a handbag, it looks very good and beautiful, but when you use it, you will find that the cardboard is too hard and it is inconvenient to load and fold. For another example, when making the cover of a magazine, book or sample, you may feel crisp with a copperplate card, but when you use it, you will find that because the paper quantity of the inner page is relatively low and the paper is soft, the contrast with the handle of the cover is too large, and it is not very convenient to turn the page. At the same time, it is easy to form creases on the cover after opening, resulting in the bursting of the coating or printing ink. Although pre indentation can alleviate this problem, it is still obvious on the paper jam. In addition, books and magazines with cardboard covers cannot be rolled up because they are too stiff, which makes it inconvenient to post and carry

in a word, coated paper and coated card, which are two kinds of paper designed for different purposes, have certain advantages and disadvantages respectively. Users should fully understand the characteristics of these two kinds of paper, make full use of the advantages of paper to obtain satisfactory products

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