How to improve the flexo printing quality of corru

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How to improve the flexographic printing quality of corrugated boxes (boxes) (I)

color corrugated boxes (boxes) play an important role in product packaging. Because the paper packaging is pollution-free, meets the requirements of environmental protection, and the cost is low, it is more and more favored by businesses

the prosperity of commodity economy and fierce market competition have promoted the improvement of product packaging quality. Beautifying packaging has become an important means of marketing and publicity. The printing quality of corrugated boxes has been paid more and more attention by commodity manufacturers and consumers

with the progress of carton technology and packaging machinery, the scope of corrugated carton packaging is becoming larger and larger. It can not only package mechanical parts and electrical components, but also package motorcycles, washing machines, refrigerators, pianos, etc. As the packaging demand for commodities above 50kg will increase significantly, the demand for heavy corrugated paper packaging boxes such as five layer, seven layer and nine layer will increase significantly

I. advantages of corrugated box flexo printing

with the development of flexo printing technology, flexo printing technology has been gradually adopted for corrugated box printing. According to records, 98% of corrugated boxes in the United States and 85% in Western Europe use this printing technology. The printing trend of corrugated boxes is from monochrome and two-color to multi-color line printing, and from outer packaging (transportation packaging) to high-end sales packaging. Flexible printing corrugated box has the following advantages:

1 Flexo printing can print both field version and line version

foreign countries tend to use e corrugated board with white face paper (coated white cardboard or 80g/m2 single-sided copper once damaged, which will seriously affect the use of master paper and offset paper of the experimental machine), and use 100l/in to print high-grade corrugated color boxes. Printing on various types of rough corrugated is generally below 80l/in, usually 40 ~ 60l/in. When printing line plates on kraft paper, they are generally not printed in three primary colors, and the number of lines added should not exceed 60l/in

2. Flexible version is flexible

the flexo is soft and elastic, which can compensate for the thickness error and uneven surface of the corrugated board with its own compression deformation during the printing process, so as to make the ink layer more uniform, so as to improve the printing quality

3. Flexographic printing belongs to soft press printing

due to the corrugated board, the pressure on the corrugated board is uneven during the printing process. The pressure on the high part of the corrugated board is large, and the pressure on the low part of the corrugated board is light. Sometimes, the low corrugated board cannot be contacted, and the ink cannot be printed. Offset printing and gravure printing can not overcome this defect, resulting in serious corrugation marks. Flexographic printing is a kind of light press printing. After the compression deformation of the printing plate, it can better contact the corrugated board, and the high part of the corrugated board will not have serious marks or even crush the corrugated due to excessive pressure

4. Flexographic printing can use water-based ink

flexographic printing uses a metallic roller ink transfer system, which can use water-based ink. Using water-based ink to print corrugated boxes, the printing plate only needs to touch the corrugated board gently, and the water-based ink will be absorbed almost completely

5. Flexo printing machine has simple structure

the corrugated box has a large area, and the length of the cardboard can reach 2 ~ 3M. If offset printing is used, the equipment is huge, and the operation and maintenance are difficult. The flexo printing machine has a simple structure, four rollers form a color group, and the mechanical performance and stability can be improved after the diameter of the roller is increased. It is very convenient to install, adjust and clean

6. It can form a linkage production line with other processing equipment

due to its simple structure, flexographic printing machines can be linked with other processes for production. Now most corrugated board printing machines are combined with indentation machines and slotting machines for on-line production. It forms a printing production line together with indentation, slotting, die cutting, gluing, box making and counting devices, which can directly print corrugated boxes for one-time forming

in a word, the best way to print corrugated boxes is flexo printing, which has been agreed at home and abroad

II. Structure and specification of corrugated paperboard

the high-strength paperboard made by bonding face paper on the corrugated core paper (the profile is wavy and similar to corrugated) pressed by the corrugated machine is called corrugated paperboard. The stress of corrugated board is basically similar to that of arch, with greater rigidity, good bearing capacity, elasticity and high shock resistance (see Figure 1)

the shape of corrugated board is directly related to the compressive strength of corrugated board. According to the shape of the corrugated core, the corrugated board can be divided into U-shaped, V-shaped and UV shaped

u-shaped corrugated board has good tensile strength, elasticity and high energy absorption. Within the elastic limit, the corrugation can still be restored after the pressure is removed

v-shaped corrugated board has good compressive strength, but when the pressure exceeds the limit it can bear, the corrugated board will be destroyed quickly

uv corrugated board has a performance between U-type and V-type. It is widely used. Thank you again for your great support to our company

the performance of corrugated board is not only related to the shape of corrugated board, but also related to the specification of corrugated board. It is generally divided into type A, type B, type C and type e. the specifications of various corrugations are listed in Table 1

table I comparison of compression in different directions of corrugated type and corrugated plate

peak height of corrugated type/mm number of corrugated lines/m plane compression of corrugated plate transverse compression along the corrugated line longitudinal compression

a 4.5 ~ 4.8 120 ± 10441

b 2.5 ~ 3170 ± 11223

c 3.5 ~ 3.7 140 ± 10332

d 1.1 ~ 1.2 320 ± 13114

a corrugated type has excellent shockproof and cushioning performance, and the vertical compressive strength is better than that of type B (see Figure 3). The shockproof performance of C-type corrugated board is similar to that of A-type corrugated board, and the plane compression resistance is close to that of B-type corrugated board. A and C-type corrugated board are also ordered to be used for external packaging. The plane compression resistance of type B corrugated is higher than that of type a corrugated. There are more corrugated in the unit length, and there are more supporting points with the face paper and the lining paper. Therefore, it is not easy to deform, and the surface is flat. It has strong pressure resistance and is conducive to good printing effect. Type B corrugated board is mostly used for medium packaging. E-type corrugated is the thinnest kind of corrugated. The height of corrugated is about 1mm. It must be known that the number of corrugated in a unit length is the largest number of computers, which can withstand large plane pressure and print high-quality graphics and texts. Its strength is similar to that of cardboard, but it is lighter and cheaper than cardboard. As mentioned above, it is mostly used for inner packaging. Recently, K-type extra large corrugated board has appeared in the world, with the height of 6.6 ~ 7.0mm and the number of corrugated boards per meter is 75 ~ 85; The height of the micro corrugated n-type is 0.5mm, and the height of the F-type is 0.75mm. The height of G-type corrugated is 0.85mm

corrugated board can be divided into single corrugated board, three-layer corrugated board, five layer corrugated board and seven layer corrugated board according to the composition type

single corrugated board is made of a piece of face paper and a piece of corrugated core paper. It is rarely used as an external packaging, but mostly as an internal packaging and packaging liner

the three-layer corrugated board is made by sticking a piece of face paper (such as kraft paper) on both sides of a corrugated core paper. It is mostly used for medium-sized packaging or small outer packaging cartons

the five layer corrugated board is composed of three pieces of corrugated core paper and two pieces of corrugated core paper bonded together, and the order is face paper, corrugated core paper, core paper, corrugated core paper and inner paper. Generally, A-B type ridge combination is adopted, and a-c type, B-C Type, A-E type and B-E type combination can also be adopted. The five layer corrugated board has greater strength than the three-layer corrugated board, and the loading is stable. It is allowed to make cartons with large specifications and large load capacity

the seven layer corrugated board is composed of four sheets of corrugated paper, including inner, surface, core and core, and three sheets of corrugated core paper. The ridge type usually adopts b-a-b type, or a combination of B-A-A, c-a-c and b-a-c types. Seven layer paperboard has the same characteristics of transverse and longitudinal compressive strength, which can increase the longitudinal strength and reduce the thickness of paperboard. It is mainly used for the packaging of heavy commodities. Corrugated board is now developing in the direction of high strength, low gram weight, multi corrugated type and high quality

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