PS version of the key to development

PS version must be developed after the exposure to form images, and made on the machine printing plate. The development of the PS plate is actually the dissolution of the exposed, decomposed resin with a basic solvent. This process seems simple, but it is really necessary to show a qualified plate, and there are still strict requirements on the developer and the development process.

Developer

1. Composition of developer

The PS version of the developer consists primarily of salts formed by alkali or weakly basic weak acids, specifically NaOH (KOH) or Na2SiO3 or a mixture of NaOH (KOH) and Na2SiO3.

The components of the developer include not only the main components NaOH, KOH (NaOH in our country, KOH in Europe and America), but also Na2Sio3 or NaOH and Na2Sio3 in a certain proportion; but also The buffering agent, Na2SiO3, actually has a certain buffering effect; and the inhibitor, KCl or NaCl or trisodium phosphate, is used to prevent the formation of acid in the air by the CO2 in the air during the use and storage of the developing main agent. N a OH produces a neutralization reaction to reduce the drug; also add a certain amount of wetting agent, such as sodium dodecyl sulphonate, Tween and other surfactants, the amount should not be much, and many easy to produce a large number of bubbles and affect the development Processing. If using tap water to prepare the developer, it is best to add a small amount of EDTA -2 sodium, complex calcium, magnesium ions in water. To prevent air bubbles from developing, it is best to add a small amount of defoamer, such as n-butanol, to the developer.

2. Selection of developer

For PS version of the development, the choice of developer is a prerequisite.

In actual operation, there are many users who use self-developed developer, that is, NaOH or Na2SiO3 or both are mixed in a certain proportion to be developed into a certain concentration of aqueous solution for development. Although this can achieve the purpose of development, the development effect is not Too ideal. Some manufacturers use Na2SiO3 single component formulated developer, this approach is not desirable. Because if the concentration is low, the developing ability is not enough; if the concentration is too large, it will easily form crystal scale and affect the use.

In recent years, due to the development of technology and the progress of society, developing machines have become more and more popular. Most printing companies now use machine displays. Developers also purchase special concentrate developers from the market. When used as long as the water is diluted in a certain proportion, it is convenient and quality assured. The machine has a high requirement for the developer. The developer used in the machine can not be said to change. The developer must be used for a period of time. According to the amount of the plate, it can be replaced once a week or two weeks. This requires that the developer be stable, durable, and has good impact resistance. Of course, the developer must be continuously replenished in order to maintain the drug.

As the PS version of the resin continues to improve, the PS version of the photographic performance is also constantly improving, the exposure time is short, the development is often not too strong developer, this will not only reduce the cost of the development process, but also conducive to environmental protection. Therefore, the traditional NaOH as the main developer has evolved to Na2SiO3 as the main developer, NaOH has become a development accelerator.

At present, most PS sets of pharmaceutical companies use Na2SiO3 and NaOH to prepare the developer at a certain proportion. The proportion is appropriate. Both have strong developing ability and good stability and impact resistance.

When all major PS manufacturers in China sell their own PS versions, they also deliver special developer solutions. Some manufacturers do not distribute them, and they also sell supporting developer solutions. Users do not have such problems if they use the manufacturer's specified developer dilution density and the recommended development processing conditions.

When buying, please be careful not to use brand-name, inferior developer in the market. In these years of market technical services, we often encountered some users with poor quality developing solution and appeared to be not clean, out of print, low print resistance and other issues. Because many of the cheap no-brand developers are made from cheap, low-grade raw materials by the manufacturer, they are often vulnerable to photosensitive coatings when developing, light affects printing, and heavy printing, and cannot be printed on the machine. In the spring of 2004, many users in the East China region reported that the printing plate was not able to print or print. After investigation, all manufacturers who used to reflect the non-resistance of India were using the same brand of developer. After analysis, they used poor quality developer with unqualified raw materials.

In addition, different grades of PS version, because of its different choice of resin, the adaptability of the developer is often not the same. As we all know, if we use the processing conditions of Fuji PS version to develop Agfa's version, it is often not easy to clean; and if we use Fujifilm's version of the processing conditions to develop Fuji PS version, often thin coating, affect the network, network cable Quality, reduced version of the resistance to printing force, the severer ones are the sensitization of the photosensitive resin layer, resulting in the printing plate being scrapped.

Huaguang PS version, the early release of Y P-I type positive PS version is resistant to alkali, such as the developer is often weak is not clear, the printing plate on the machine to print dirty. The YP-II positive PS version, which was later introduced, does not need to be developed with too much alkaline developer. The YP-S positive PS version, which was later introduced, is suitable for developing weaker developers, which is also environmentally friendly. If the YP-S version is developed with processing conditions of Y P-I type, it may be obvious that similar problems have occurred in Guangdong in 2004. Huaguang YP-S positive PS version, because of its fast speed, only Y P-II version of the 2/3 exposure, outlets, network cable quality is good, many manufacturers choose. At that time, Huaguang PS version did not deliver the drug, and users used the locally produced developer to process it. As a result, many users reported that the Huaguang PS version was not printing or was out of print. For this purpose, we collect the developer from the market specifically for comparative testing and analysis. As a result, the developer of this grade was too basic, and further analysis revealed that too little buffer was added to the developer. Low developer concentration, insufficient developing ability, large developer concentration, and too strong alkalinity tend to corrode the resin layer of the plate and are not yet resistant to impact. For this reason, this information is timely fed back to the manufacturer of the kit (this kit manufacturer is well-known in Guangzhou). The manufacturer adjusts the formula of the kit in a timely manner, and later the user no longer reflects that the PS version of Huaguang is not printing. Off the plate.

Therefore, the PS version of the processing, the choice of developer is the primary. China's Huaguang, Taihang, Keyi, Abixi and other brands of PS version of the developer quality is still trustworthy.

Development process

After the developer is selected, the concentration, temperature and time of the developer become the three elements of the quality of the printing plate.

Development density

The concentration of self-aligning developer is generally known to the operator based on his or her own experience. On the other hand, the developing kits used for the machine must strictly control the dilution ratio. The developer kit manufacturers generally recommend a dilution ratio, which is generally 1:1:1 to 1:8. The ratios used by different users are different. The developer concentration is very important for the quality of the PS plate. Huaguang YP-S PS version used Huaguang PD type developer as an example, we do a set of tests with different dilution ratios. The results are shown in Table 1.

It is apparent from Table 1 how much the dilution ratio of the developer concentrate affects the development result. For a condition of 1 minute of development at 23C, the dilution ratio of the developer is 1:6.

With the PS version developer quality monitoring, the pH value did not change significantly with the developer concentration, and the developer corrosion to the electrode was severe. Measuring the conductivity of the developer is an effective method. The corresponding conductivity of different concentrations of PD type developer is shown in Table 2.

The positive-discharge version of the PD-type positive-acting PS plate developer is diluted to 1:6 by one liter of the original solution, and can be flushed by 20.63 m2/L without replenishment. This is the plate size obtained in the case of continuous stencil printing. the amount.

2. Development temperature

For the PS version of the control of the development temperature, machine display is generally not a problem, usually controlled at 23 ~ 28 °C, the development temperature of this range is the most suitable for the PS version of the processing. The developing temperature is too low, and the developing speed is too slow; if the developing ability of the developing solution is further reduced, it is often still not clear. If the development temperature is high, the entire coating layer is often thinned during the development, which reduces the printing plate's resistance to printing. Furthermore, the resin layer of the plate may be destroyed, and printing on the machine may not be possible.

For manual development, the temperature of the developer must be controlled. When the PS version is developed, the temperature of the developer is often well controlled in northern China. Because there is heating in the winter and the interior is not too hot in the summer, in the south, sometimes the temperature in the summer is too high, the developing temperature tends to fall, and there is no room in the winter. Heating, room temperature is very low, sometimes only a dozen degrees or even less than 10 degrees, such a low temperature is difficult to clear the exposed PS version. Over the past few years, we have encountered this situation from time to time when we are providing technical services to the market. Once a customer in a certain area of ​​Jiangsu Province reflected many small blue dots on the layout. For this reason, we went to the scene to check, the layout is not a small blue point, is a small green point, is not clear and left the green resin point. Measurement of the development temperature, only 14 °C, the developer concentration is not high, the development time is not long. The development temperature was raised to 23°C on the spot, and the plate was clean after development. The same situation was encountered from time to time in southern China in the past few years, mostly unskilled plate-making workers, often without paying attention to the development temperature.

For the development temperature, we also performed a set of tests. The results are shown in Table 3. The printing plate was Huaguang YP-S type positive PS plate, and the developer was Huaguang PD type developer. The developer concentration was 1:6 and the developing time was 1 minute. As is apparent from Table 3, if the development temperature is too low, the exposed PS plate is not clean.

3. Development time

The development time has a great influence on the quality of the printing plate. Early introduction of the PS version of the book, the development time is often recommended to control between 30 seconds to 2 minutes. In previous years, manufacturers of PS versions often recommended to develop for one minute when recommending the conditions for use of the PS version. In these years, we learned that few users have developed a product for 1 minute when it comes to technical services in the market. It takes more than 20 to 40 seconds to develop the product, regardless of whether it is a machine display or a manual display.

For machine display, the development time of the developing machine is set in the range of 10 to 70 seconds, and the actual control is within the range of 20 to 30 seconds. Of course, for the industries that print different prints, the control of the development temperature is also inconsistent. For exquisite color platemaking, the development conditions are often mild, ie, the developer concentration is not too concentrated (generally controlled in stock solution: water = 1:4 to 1:6). The development temperature is not too high, generally 23 to 26 °C, the development time is generally controlled between 30 and 60 seconds. With this type of display, the quality of outlets and network cables is good; printed products are vivid and vivid. Of course, the exposure is usually controlled at level 3 clean, even level 2 clean.

For newspaper printing, it is usually the first consideration of timeliness, and the shorter the time required for making plates, the better. They often use high-exposure, strong-develop processing, that is, the exposure is overexposed, and the printing plate is controlled to a Class 5 cleanness. Some newspaper printing companies still have control of Class 7 or even Class 8 clean. For the processing of the sunned version, the stronger the developer concentration is, the better the control is in the stock solution: water = 1:2 to 1:4, there are many manufacturers with a developer concentration of 1:2, and there are even newspaper printing houses. Develop at a 1:1 concentration. The shorter the development time, the better. Generally, it is controlled in the range of 20 to 30 seconds. There are a few factory development time of only 7 to 8 seconds, and there are also a lot of manufacturers that control between 10 and 20 seconds. The control of the development temperature is high, with a minimum of 25°C and a high of more than 28°C. In this way, the time for making plates is shortened, but the quality of the manufactured plates is often not ideal, and sometimes even such problems occur.

Of course, for a newspaper printing company, the exposure control is more than 5 grades. The general version will not leave leather stamps and no revision is required.