The influence of the hottest base paper on the qua

2022-08-19
  • Detail

The influence of base paper on the quality of carbon free copy paper

Abstract: there are many factors affecting the quality of carbon free copy paper. This paper analyzes the influence of base paper factors on the color development and warpage of carbon free copy paper from the perspective of base paper production. The influence of imported base paper and domestic base paper on the quality of carbon free copy paper was compared

key words: coated base paper; Carbon free carbon paper; Quality; Influence

carbon free carbon paper, also known as force sensitive carbon paper, pressure-sensitive recording paper or NCR paper, was invented by NCR (national cash register) Company in the United States in 1954. After decades of continuous development and improvement, the production technology has been quite mature at present. Carbon free copy paper is also a kind of coating processing paper. Carbon free carbon copy paper is used more and more widely because it does not need to add carbon coated paper between paper and paper, has the function of direct copy and direct color rendering, and has the characteristics of low pollution and convenient use

since the first introduction of carbon free carbon paper production lines in 1984, China has more than 40 production lines with an annual output of more than 240000 tons. The annual demand for carbon free carbon paper in China has also reached 200000-250000 tons, double that of previous years. Manufacturers with better product quality have seen a situation of supply exceeding demand. This paper will analyze the base paper in the production of carbon free copy paper, and discuss the influence of base paper factors on the quality of carbon free copy paper

1 basic characteristics of carbon free copy paper

carbon free copy paper can be divided into its contained and self contained, also known as SC paper, in terms of color development, of which its colored carbon free copy paper is the most used. In terms of color rendering, it can be divided into black, blue, red, purple, etc., of which black and blue are the most used. In terms of structure, it can be divided into upper paper or coated back paper, medium paper or coated front back paper, and lower paper or coated front paper. In terms of varieties, it can be divided into flat paper and web paper. From the aspect of appearance, it can be divided into white, red, yellow, blue, green, etc. The carbon free copy paper matching sheet is composed of the upper sheet and the lower sheet. To get more copies, just insert multiple medium sheets between the upper sheet and the lower sheet

2 factors affecting the quality of carbon free copy paper

the main performance indicators for evaluating the quality of carbon free copy paper are: (1) the clarity of multi copy (the most intuitive); (2) Color sensitivity; (3 for example, belt pulley and gear need to be checked regularly) color rendering speed; (4) Light resistance; (5) Pollution; (6) Warpage; (7) Appearance, etc. There are many factors that affect these properties. This paper only discusses the influence of base paper properties on the quality of carbon free copy paper

2.1 influence of base paper uniformity

the uniformity of base paper refers to the uniformity of quantitative, thickness, moisture, fiber tissue, smoothness, etc. in the vertical and horizontal directions. The homogeneity of base paper will directly affect the coating process of carbon free copy paper and the quality of products. Base paper with poor uniformity will cause uneven coating amount, uneven drying, inconsistent deformation after coating, and ultimately affect the use of products. Therefore, the carbon free copy paper produced by base paper with poor uniformity is mostly flat paper and cannot be sold as web products. At present, domestic evaluation of the quality of carbon free carbon copy paper products (high-grade or low-grade), the most intuitive is the appearance quality of coated paper. Products coated with base paper imported (referring to Hokkaido or Showa in Japan) or produced by a few domestic manufacturers such as Guanlong, Shouguang, jinhuasheng, etc. are generally considered to be high-grade products, and those coated with other domestic base paper are low-grade base paper, This is because the homogeneity of imported base paper is better than that of domestic base paper (except Guanlong, Shouguang and jinhuasheng) (see Table 1). Of course, in addition to the base paper factor, the software and hardware technology of coating must also be considered in the comprehensive evaluation of the product quality of carbon free copy paper

most of the base paper used in the production of carbon free copy paper is 35~80g/m2, and the thickness range is 45~100 μ M, at present, the most commonly used base paper of more than 0.01~500mm/min is 40g/m2. The weight and thickness of the base paper have a direct impact on the multicolor development. The same weight and different thickness of the base paper, the same number of copies of the color development effect is different. For example, the thickness of 40g/m2 domestic base paper (except Zhanjiang Guanlong, Suzhou jinhuasheng and Shandong Shouguang) is generally 10%~15% thicker than that of 40g/m2 base paper imported from Japan. In this way, under the same coating amount, the multicolor effect of carbon free copy paper produced by domestic base paper is bound to be worse than that produced by imported base paper with the same amount

2.2 influence of base paper permeability

some people think that the permeability of base paper used for carbon free copy paper is more suitable at 100~150ml/min, but in fact, base paper with permeability in the range of 100~150ml/min, especially domestic low-grade base paper, is very difficult to solve the warpage quality paper disease caused by single-sided coating, and a considerable number of manufacturers have to use the way of glue or water coating on the back, Some manufacturers cannot directly add water and glue coating equipment on the coating due to the inherent shortcomings of the coating machine, so they have to adopt the way of re coating to solve it. However, the air permeability of base paper with good quality, such as Japanese Hokkaido base paper known as the "king of paper", or Shandong Shouguang and Zhanjiang Guanlong base paper, is basically in the range of 200~400ml/min. after one-sided coating, there is no need to carry out special back coating treatment (gluing or water coating), and only a small amount of steam can be sprayed on the non coated surface to meet the requirements of warping quality indicators (national standard a, etc.). In actual production, the base paper with air permeability of 350~550ml/min has no adverse effects after being coated with the middle sheet (such as self color development due to the penetration of positive and negative coatings, and uneven drying). The base paper with high air permeability is helpful to solve the warpage quality and paper disease of the coated paper

2.3 the shrinkage of base paper and the influence of holes

the expansion rate of base paper used in the production of carbon free copy paper is generally required to be no more than 3.0%, and there should be no holes. The expansion rate of base paper is too large, which will not only cause difficulties to the post-processing of coated paper, but also affect the use of final products, such as the dislocation of printed up and down forms. In addition, theoretically, if the paper has too large expansion rate, the coating, especially the microcapsule coating, will be damaged during coating drying. The internal stress generated by drying shrinkage will cause some microcapsules to shift and crack, and colorless dyes will flow out and color. However, in actual production, due to this situation, there are few quality paper defects caused by color rendering. For the base paper used in the production of carbon free copy paper, pinholes are not allowed to exist, but in fact, there are many pinholes in the coated base paper. After coating, it is not found that these pinholes will penetrate the coating and affect the product quality. This may be the reason why the pinholes are covered by glue after surface sizing during the production of base paper. Of course, the most taboo of the base paper used in the production of carbon free copy paper is that there are holes in the coated base paper, which will make the paint pass through the holes to the other side of the paper and cause color rendering. According to rough statistics, if a bundle of 40g/m2 base paper (10000~12000m long) has holes, the loss caused by the bundle of base paper coated with paper will be greater than 0.20%. The larger the hole in the base paper, the greater the loss caused by coating

2.4 effect of base paper surface strength and ash

the powder and hair loss of carbon free carbon copy paper is not only related to the coating formula, but also directly related to the surface strength and ash content of coated base paper. Under the same coating formula, the phenomenon of powder and wool falling after coating of base paper with high surface strength and low ash content is obviously different from that of base paper with low surface strength and high ash content. The former has less powder and wool falling, while the latter has serious powder and wool falling. The surface strength of base paper and coated paper is usually measured by the speed of roughing. The galling speed of imported base paper (Japan) is in the range of 2.08~2.61m/s, and the ash content is about 5%. The galling speed of domestic base paper (excluding Guanlong, Shouguang, etc.) is in the range of 1.06~1.20m/s, and the ash content is about 10%. The galling speed of coated (CF paper) is 1.29~1.61m/s and 0.61~0.84m/s respectively. In order to improve the problem of powder and wool loss of domestic base paper after coating, it is usually to increase the amount of adhesive in the coating formula, but the increase of the amount of adhesive is bound to affect the color development effect of carbon free carbon copy paper. Therefore, the base paper used in the production of carbon free copy paper should use the base paper with high surface strength and low ash as much as possible

2.5 influence of base paper smoothness

the smoothness of base paper will directly affect the quality of products and the printing of products. It has a greater impact on the non pressure light distribution equipment of the coater. The base paper with high smoothness, after coating, the smoothness of the product is also high, and the adaptability to printing is also good. For example, if the smoothness is greater than 50s and less than 30s, the smoothness of base paper coated with CF and then calendered can be improved by more than 50%, but after coating with CB (not through calendering equipment), the smoothness of the former is generally 16~19s, and the smoothness of the rear vacuum heat insulation board is generally 9~12s, which is obviously rough. The base paper with low smoothness has poor uniformity of coating distribution in the paper after coating, and the color density of coated products is low. In addition, the products with low smoothness have rough surface and poor abrasion resistance, so the products are prone to pollution. It is generally required that the smoothness of the base paper for the production of carbon free carbon copy paper should be greater than 50s on the front, and the positive and negative difference should not be greater than 20%

2.6 influence of base paper sizing degree and water absorption

base paper sizing degree is closely related to water absorption. Base paper with high sizing degree has low water absorption, and base paper with low sizing degree has high water absorption. For the base paper usually used for carbon free carbon paper coating, the sizing degree is required to be 1.0~2.0mm (scribe method), and the water absorption is 15~20 g/m2 (cobb60). The sizing degree of imported base paper is generally 2.0mm, and the water absorption is about 16g/m2, so the coating amount is moderate after coating; The sizing degree of domestic low-grade base paper is basically about 1.0mm, and the water absorption is more than 20g/m2. The base paper with low sizing degree and high water absorption has a large coating amount. The coated paper is easy to deform, the coating cost is also high, and the pollution of the paper is also serious

2.7 effect of base paper tensile strength and surface pH value

the tensile strength of base paper can be divided into longitudinal and transverse, including dry tensile strength and wet tensile strength. The tensile strength of the base paper, especially the longitudinal tensile strength, mainly affects the coating of carbon free copy paper. The base paper with high tensile strength has less coating loss, on the contrary, the coating loss is large. Generally, the dry tensile strength of the base paper used in the production of carbon free copy paper is required to be no less than 2.0kn/m, and the wet tensile strength is 8% - 10% of the dry tensile strength

the pH value on the surface of base paper is best in the neutral range. For paper with low surface pH, this innovative technology is based on the utilization of a heat latent curing agent material, which is brittle and easy to turn yellow; In addition, because the capsule wall of microcapsules is not absolutely impermeable, the blue phenomenon will occur when five color dyes penetrate out of paper with low pH value

2.8 effect of base paper tightness

the tightness of base paper mainly affects the coating of coated paper. For paper with inconsistent tightness, it is difficult to load the side with high tightness, which will cause uneven loading of the whole width and color spots (in the production of colored paper). In serious cases, it will also cause that some positions cannot be loaded, causing missing coating. Holiday coating is a serious quality paper disease for carbon free copy paper, which is never allowed. Therefore, the coated base paper used for carbon free copy paper requires that the overall tightness should be consistent

Copyright © 2011 JIN SHI