What are the consequences of improper use of the rubber roller? First of all, in the printing quality, the uneven color of the printed matter, the color is not full, the mottled color, the ink stick, the dot gain and the like are all caused by the rubber roller.
1. Cobalt oxide: usually cobalt oxalate or cobalt carbonate as raw materials calcined at 500-600 ℃ cobalt oxide, the main reaction is as follows:
CoC2O4 == CoO + CO + CO2; CoCO3 == CoO + CO2
2. Cobalt hydroxide: It can usually be neutralized with sodium hydroxide solution in cobalt chloride solution or cobalt sulfate solution. The main reactions are as follows:
Co2 ++ 2OH - == Co (OH) 2 Co (OH) 2 + O2 + 2H2O == 4Co (OH) 3
3. Cobalt chloride: usually available cobalt powder with dilute hydrochloric acid into cobalt chloride solution, and then crystallized by evaporation of cobalt chloride crystals, the main reaction is as follows: Co + HCl --- COCl2; Co + H2SO4 --- COSO4
4. Cobalt sulfate: usually cobalt oxide as raw material, dissolved in sulfuric acid after evaporation crystallization of pink cobalt sulfate crystals, the main reaction is as follows: CoO + H2SO4 == CoSO4 + H2O
5. Cobalt carbonate: It can usually be obtained by precipitation with sodium carbonate solution in cobalt chloride solution or cobalt sulfate solution. The main reactions are as follows:
CoCl2 + Na2CO3 == CoCO3 + 2NaCl
6. Cobalt oxalate: It can usually be precipitated with ammonium oxalate solution in cobalt chloride solution or cobalt sulfate solution. The main reactions are as follows:
(NH4) 2C2O4 + CoCl2 == CoC2O4 + 2NH4Cl
7. Oxidation of high cobalt: cobalt carbonate or cobalt oxalate can usually be heated in oxygen, further oxidation obtained, the main reaction is as follows:
3CoCO3 + O2 ==== Co2O3 ++ CO2; CoC2O4 + O2 ==== Co2O3 + CO2 + CO
8. Cobalt Hydroxide: 4Co (OH) 2 + O2 + 2H2O === 4Co (OH) 3; 2Co (OH) 2 + NaClO + H2O == 2Co (OH) 3 +
2Co (OH) 3 + 6HCl == 2CoCl2 + Cl2 + 6H2O
Analysis of the causes of improper use of rubber rollers
Established in 2001, Dongguan Haichang Hardware & Rubber Co., Ltd. is a professional manufacturer of various industrial rubber rollers and printing machinery rubber rollers. Over the years, relying on strong technical force, advanced machinery and equipment "target=_blank> mechanical equipment, scientific management mode and pragmatic spirit of refinement, with integrity and quality as the purpose, the market share continues to expand, praised by the majority of users .
First, the reasons for the improper use of rubber rollers:
What are the consequences of improper use of the rubber roller? First of all, in the printing quality, the uneven color of the printed matter, the color is not full, the mottled color, the ink stick, the dot gain and the like are all caused by the rubber roller. Second, the hidden behind the impact of quality, that is the cost. Improper use of the rubber roller can cause downtime and increase the extra cost of the enterprise.
In addition, it will also reduce the life of the rubber roller, so we need to spend more money to buy more rubber rollers.
In general, improper use or selection of rubber rollers will reduce the company's profits. Therefore, we must properly adjust and maintain the rubber roller to reduce costs. How is the rubber roller made? Rubber technology is an esoteric science, and print users only need to understand its basic structure.
The hardness of raw rubber is generally 60 to 80 degrees. If it becomes a rubber roller, we need to use a vulcanizing agent to vulcanize the rubber at a high temperature. If the structure of the raw rubber is regarded as a chain structure, the rubber molecular chain will cross after vulcanization. The structure is structural and has a certain elasticity, and the rubber can be processed into a desired shape. At the same time, this structure can also lock the plasticizer in the rubber roller to prevent the rubber roller from shrinking. Thereafter, the plasticizer is used to reduce the hardness of the green rubber to the desired hardness.
In addition, some additives such as additives and fillers are added to enhance the performance of the rubber roller, and these adjuvants are also the core technology of Norden.
At present, there are more than 200 kinds of plasticizers on the market, and the rubber rollers of poor quality will ooze out after plasticizing for a period of time, causing the rubber rollers to shrink, and for good rubber roller products, the plasticizers. It will not leak out. What is the surface of the rubber roller? The surface of the rubber roller is like a hill. The printing factory calls it the printing surface of the rubber roller. How is such a surface formed?
First, the rubber roller rubs against the grinding tool to form a hill-shaped printing surface on the surface of the rubber roller, and such a printing surface can achieve good ink transfer and water transfer. But be aware that we need to protect this surface very well. Just like we use a clean brush to paint the wall, the wall must be very clean and beautiful. If it is not cleaned in time after brushing the wall, the brush will dry out and be connected to the rubber roller, that is to say, the surface of the rubber roller will be knotted. Glaze, it does not transfer ink and water well.
Usually, every time the printing machine is used for one month, it should be checked whether the surface of the rubber roller is glazed. The usual method is to touch it by hand. If there is resistance on the surface of the rubber roller, the rubber roller can continue to be used. Slippery, the rubber roller has been glazed. Why pay attention to the rubber roller of the rubber roller? Do we need to relate the width of the ink bar?
Yes, this is very important.
As you can see, in the printing process, the ink roller, the water roller, the plate roller, and the pressure plate roller have contact points for each other. If we choose the appropriate ink bar, then the printing pressure is appropriate. The rubber roller can transfer ink well, so that the rubber roller keeps the temperature low during the operation and prolongs its service life.
We recommend that customers use the ink bar to maintain the accuracy of the ink bar. Of the large customers we often touch, very few people will be able to recognize at a glance that the width of the ink bar is 4 mm or 6 mm, so the most Good use of the ink bar.
The rotation of the hard roller is driven by the gear, so the pressure in each place is the same. When the ink roller and the hard roller are in contact, a nip is formed. At the contact point, the speed of the rubber surface is lowered to be smaller than that of the hard roller, which causes a speed difference, which is called shearing force, which is why the rubber roller can transfer ink. the reason.
Second, the effect of the width of the ink bar does not match:
If it requires a 4 mm ink bar and our ink bar is 4 mm, then the pressure is uniform. If the ink bar is too large, the ink will cause ink in the nip during the transfer. The accumulation of ink makes the ink convey unevenly, eventually causing chromatic aberration. What effect does the width of the ink stick do not match?
(1) If we want to make a 4 mm ink bar, but it is 8 mm, the printing pressure will cause the rubber roller to rub and heat. After a few weeks, we will find that the rubber roller is glued. . If the ink bar is only a little wider, after 6 to 8 months of use, the rubber molecular chain will also be broken, and the rubber roller will be glued.
(2) If there is a depression in the middle of the ink stick, this problem cannot be solved by adjusting the rubber roller. There are many reasons for this, such as the rubber roller being accidentally bumped during use. At this point, only one rubber roller can be replaced.
(3) If the middle of the ink stick is small, it means that the pressure of the rubber roller and the squeezing roller is too large.
We did a survey and tracked the use of different products. In the first month, the printing pressure was relatively large; in the second month, the pressure was reduced by about 50%. Statistics showed that the second month saved 59% of the electricity, the ink saved nearly 27%, and the dampening solution used also saved. 15%.
Therefore, it is recommended that when the customer touches the ink bar, the pressure value should refer to the parameters provided by the machine manufacturer. Do I need to reposition my position when installing a new rubber roller? Always re-adjust the position of the rubber roller before installing a new rubber roller!
If the rubber roller has been used for one year, it needs to be replaced with a new one. If we do not adjust the position of the rubber roller first, the rubber roller will be deformed when it is installed. At present, the outer diameter of the new rubber roller of Norden is larger than the previous one. Therefore, if the original pressure and nip are used without re-adjustment during installation, the rubber roller will be deformed.
Why not adjust the position of the new rubber roller, the rubber roller will be deformed? That is because during the rotation of the rubber roller, the speed of the rubber roller surface at the nip will decrease, the surface speed will decrease, and then the deformation will rebound and heat will be generated.
For example, if the speed of the printing press is 10,000 sheets per hour, the number of deformations of the rubber roller at the contact point is as high as 50,000 times; if it happens that the rubber roller is against the plate roller, then it is in contact with the plate roller, and the number of deformations thereof It can reach 150,000 times; for web presses, it runs faster than a sheet-fed press, and the number of times the rubber roll can be deformed is 450,000.
The rubber roller frequently rebounds and deforms, so that the rubber generates heat, which will reduce its service life. Does the idle rubber roller need to be protected? First look at a few questions that customers often ask:
“My press is six-color, but I only use five color groups. Does the rubber roller in the idling color set need maintenance?â€
“My press has a speed of only 10,000 sheets per hour. Do I need to protect the rollers?â€
“The plasticizer in the rubber roller will seep out and cool the rubber roller, so the rubber roller does not need special protection?â€
Third, then which one is right:
In fact, the plastic roller of a good rubber roller will not penetrate out, so the correct answer is that no matter whether the machine is fast or slow, you need to use the anti-static protective paste to protect the rubber roller. In one hour of operation, the rubber roller will produce tens of thousands of deformations. If there is no protection for the rubber roller during idling, although the rubber roller will not be abnormal in a short time, it will affect it in the long run. The service life.
Other customers will say that it is not possible to use oil instead of a special idler paste, because the oil will stick to the rubber roller and cannot be washed off. Can you use vegetable oil? The answer is also not acceptable. Although vegetable oil can be used as a lubricant, it is equivalent to the oil in our food. It is easy to generate heat and cause damage to rubber. Therefore, we recommend that customers use a special idling protection cream.
The use of a good idler paste will reduce the heat of the rubber roller, reduce the number of downtimes, and better clean. How should I clean the rubber roller? First understand the ingredients that form dirt on the rubber roller.
The surface of the rubber roller is in the shape of a hill. After a period of use, the surface will have water-soluble particles soluble in the solution, as well as insoluble particles. If these things are not cleaned in time, the rubber rollers will glaze and will not be able to transfer water or transfer ink.
Fourth, then, how to clean the rubber roller:
Some customers will say that they use a rubber roller cleaner because it removes insoluble particles, such as ink. However, if only the rubber roller cleaning agent is used, only the surface particles may be washed away, and the place deep in the rubber roller is not easily washed away. Some people wash the rubber roller with water, of course, it can wash away the soluble particles, but the insoluble particles can not be washed away.
In fact, rubber roller cleaning was not an important issue 25 years ago, because more and more recycled paper is now used, which is an already printed product. In order to make it white, its composition contains A lot of calcium and magnesium components, after printing for a period of time on recycled paper, there will be white matter on the surface of the rubber roller, which is the calcification of the rubber roller. How can these things be removed? We recommend that customers use cleaning products that are specifically designed to clean insoluble particles. They contain minerals and, in addition, use specialized decalcification products to thoroughly clean the rubber rollers.
5. In addition, when cleaning the rubber roller, you should also pay attention to the following items.
(1) After the rubber roller is glazed, do not use a rough rag to wipe the rubber roller. Otherwise, the printing surface of the rubber roller will be damaged, and it is easier to accumulate impurities. After the damage, the surface will be glazed, forming a vicious circle. Finally, the rubber roller can only be scrapped. .
(2) Automatic cleaning device: Some devices have automatic cleaning device, only one water tank, which is filled with car wash water. After washing the water, it is not washed with water. The rubber roller is easy to glaze, so it is recommended to clean the device automatically. With two water tanks. In addition, we recommend that the customer still use manual cleaning methods, so that the rubber roller can be thoroughly cleaned. There are ten cases of rubber roller deformation. Some customers often complain that the size of the rubber roller has been deformed. In fact, there are many reasons:
(1) Using a strong solvent or ink, such as UV ink, if the correct rubber roller is not used, the rubber roller will expand.
(2) The content of soybean oil in the ink is high, and the speed is relatively high in the rotary printing machine.
(3) The use of a strong cleaning product also causes the rubber roller to swell.
(4) Some reducing agents do not allow the rubber roller to rebound, and it is not recommended to use on rubber rollers that have been used for more than one year.
(5) The cleaning agent contains aromatics such as gasoline.
(6) Residual solvent remains and is not well cleaned after cleaning.
(7) Use a poor quality cleaning blade.
(8) Dampening solution: There is no alcohol dampening solution in the US market. All of them use alternative products. Some dampening solution with low p H value will cause orange peel phenomenon in the rubber roller.
(9) If the pressure is too heavy, it will cause heat and deformation of the rubber roller, affecting the ink transfer effect, and degumming the rubber roller.
(10) Room temperature is too high or too low. It is recommended to leave the rubber roller at room temperature for more than 24 hours before use.
*The rubber roller produced by our company has excellent formula, superior materials and advanced technology. The products include: ink roller, water roller, alcohol water roller, ink roller, polishing roller, oil roller, paper roller, laminating roller, film blowing roller, gravure roller (copper roller), offset roller, paper roller, Printing and dyeing roller, circuit board acid-resistant roller, circuit board high temperature roller, shoe composite roller, hardware, wood machinery and other rubber rollers, its performance: corrosion resistance, acid resistance, alkali resistance, wear resistance, oil resistance. It is resistant to tearing, high temperature, water, anti-static, anti-fouling, elastic and long-lasting. Can be well satisfied with paper color printing, carton printing, plastic bag printing and printing and so on.
The company has always been "customer first, quality first" as its purpose, "professional to do better, service and thoughtful" as the company's quality policy, "reputation-based, service sincerity" as the operating policy. With this, we will continue to improve and make unremitting efforts. Adhering to quality, advanced equipment, professionally designed and timely service is our commitment to every customer.
Information Sources:
Http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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