The main process of the photosensitive sheet in the manufacturing process is as follows: establishing a latent image on a photosensitive sheet - exposure; changing a latent image into a visible image - developing; stabilizing a visible image - fixing. First, the principle of the formation of latent image whether in the camera, imagesetter or scanner, when exposed to the correct exposure, always on the photosensitive film to form some of the desired image. Because it is not easily noticeable by human eyes, this image is called a latent image. How is a latent image formed? In the production process of the photosensitive sheet, in addition to the halogen-silver crystals, the sensitized emulsion is evenly distributed with silver atoms and silver sulfide molecules, which form many photosensitive centers on the surface of the photosensitive sheet.
Exposure, the light energy acts on the halogen silver (AgX) crystal, halogen halide (X Ì„) in the silver will lose one electron from the halogen atom (X), as in Figure B, the reaction formula is as follows:
The generated free electrons form electrons that move in the crystal. When they meet the photosensitive center, they are attracted by the center, causing the center to bear a negative charge. When it encounters a negative electric field, it concentrates on the photosensitive center. It is neutralized into silver atoms. Just like:
(When the exposure amount of the photosensitive sheet reaches a certain level, the photosensitive center is enlarged and developed into a developing center due to the increase of silver, which is a basis for the latent image, so the halogen element is generated and is absorbed by the surrounding colloid. Second, the latent image is formed and transferred. To convert a latent image into a visible image, the silver atoms at the development center must continue to increase until the human eye can clearly observe it. This is accomplished through the action of development.
The purpose of the development is to reduce the silver ions of the silver salt molecules in the photosensitive layer emulsion layer to the silver atoms, which is the same as the exposure, but it is done by drugs. Therefore, the development can be regarded as the continuation of the exposure.
There are many drugs that can reduce halogen silver in development, and they are all easily oxidizable chemicals. The principle of development is described with respect to hydroquinone as an example. The hydroquinone is ionized in the developer as follows:
The anion is the imaging ion, which is easily oxidized to acid and emits two electrons.
Halide silver gets electrons reduced to silver.
The combined reaction of halogen ions and red ions to generate halothane is as follows:
Exposure has a light receiving portion and an unlighted portion, and the developer acts on the entire surface of the photosensitive layer, but why is only the halogen silver at the developing center reduced to silver? This is because potassium bromide is added to the developer and it ionizes Br in the solution. The development center is a silver atom, it is impossible to adsorb Br, only Ag+ will adsorb it. Therefore, in addition to the development center, they are all surrounded by Br, forming a negative barrier. In this way, the developing ions enter the crystal from the gap in the developing center, so that the silver halide is reduced to silver. Third, the stable visible image The finished image can clearly see the image, but the stability is poor, will disappear after seeing light, if stored in the developer, then the film will have no image, therefore, it is necessary to use chemical drugs The necessary processing can only meet the requirements. This process is called fixing.
The function of the fixing is to dissolve the unsolvated and undeveloped silver onto the photosensitive sheet, leaving only the reduced silver atoms. Fixers therefore require the ability to dissolve halogen silver without destroying the reduced silver. There are many agents belonging to this group, but some are toxic and some can stain the negative film. Therefore, sodium thiosulfate (Na2S2O3) is usually used. In special cases, ammonium thiosulfate [(NH4)2S2O3] can also be used. The chemical reaction is as follows:
Therefore, both Na3[Ag(S2O3)2] and NaX are dissolved in water. Thus, the purpose of development is achieved.
In the developer and fixer, there are not only the developer and the fixer, but also other chemical agents, and each has its own function, so we only have to understand their role and they are justified in dealing with various phenomena. Fourth, the composition of the developer and its role Developer.
Developers are drugs that reduce silver halides to silver, the most commonly used being Metol and Hydex. However, it is easily oxidized in water and should be used in conjunction with other drugs.
Mitoul is also known as Yilun, whose scientific name is methyl-p-aminophenol sulfate. The molecular structure is as follows:
It is a white or slightly grayish acicular or powdered crystal that dissolves at 4.8 grams per 100 ml of water at 10°C. It is hardly soluble in an aqueous solution of sulfurous acid, it is a strong developing agent with strong visualization. The image appears very quickly. When the developer is strong, it can appear in the developer for 2 seconds to 3 seconds. Its main feature is that it can make the dark part and the strong light image appear simultaneously, but The degree of difference between light and shade or black and white on the film is small, that is, the contrast is small. Compatible developer and sulfite coexist with good storage performance and low temperature response to potassium bromide. It is comparable to Hydrangeol to the same extent, making it difficult to contaminate negative film.
Haidolinji is also known as dinitrone. Its scientific name is called hydroquinone and its molecular structure is:
Its color is gray or white, usually fine needle crystals. It dissolves 6 grams per 1000 ml of water at 20°C, and its aqueous solution turns yellow easily because it is an easily oxidized material. In order to prevent oxidation, it has good developing performance, and generally it is necessary to dissolve sodium sulfite first in water, and then dissolve Haidolin. Hydergine development is slow. Especially for those parts where the exposure is particularly low, the effect is slight, but once the image appears, the density will increase rapidly, so the film is often dark or black and white. With high-contrast developing effect, when using Hadozicone, the pH value and temperature of the solution have a great influence on the shadow effect. Therefore, the developer should be developed at a certain temperature in order to achieve a stable purpose. . It must be developed in alkaline solution. It is better to use PH value in the range of 9.5---11. The larger the PH value is, the more alkaline it is, and the greater the density and contrast of the negative film. If the temperature of the developer is lower than 10°C, the development is very slow. When the temperature is low, the developing effect is hardly developed. However, if the temperature is higher than 20°C, the development is quick, but the negative film is liable to be flawed. Back to this, when used, the temperature should be in a relatively stable range. It is often used in combination with Methocel to achieve correct development purposes. When combined with Metol, they are called M--Q. .
2. Preservatives.
The preservative is usually sodium sulfite, also known as sulphur oxide powder, and its function is to prevent the oxidation of mitel. There are two kinds of anhydrous and crystalline. Its molecular formula is Na2SO3 (anhydrous sodium sulfite) and Na2SO3 · 7H2O (crystalline). Colorless white powder, relatively stable in air; crystallized as white granules, easily oxidized into sodium sulphate in the air, so it should be sealed and stored, both can be used when used, but should pay attention to the amount, if not For 1 g of water, 2 g of crystalline was used because the molecular weight of anhydrous was 126 and the molecular weight of the crystalline was 252, which was exactly twice that of anhydrous. In the existing circumstances, we often use anhydrous to facilitate the preservation of the developer. Generally, when the temperature is high, the amount can be increased appropriately to increase the image contrast, but too much is not good for the quality of the negative film, and the halogen silver in the negative film is easily dissolved. Therefore, it is often required that the developer has a stable temperature.
3. Accelerator.
Accelerators are all alkaline substances. Usually there are 3 types of strong bases, weak bases and soft bases. Soft bases are commonly used.
(l) Soft Base. Soft alkali is mainly composed of sodium carbonate (Na2CO3) and potassium carbonate (K2CO3), and its aqueous solution has a PH value of 10.8. Alkaline is weaker. There are three kinds of anhydrous sodium carbonate, one water (Na2CO3 · H2O) and crystal (Na2CO3 · 10H2O), all of which can be used. The amount ratio of the sodium carbonate is: anhydrous: water: crystallization = 1:1.17:2.7. When the temperature is high, the dosage should be reduced appropriately. When the amount is too large, the negative film can be easily generated and the quality of the negative film can be affected. Potassium carbonate easily absorbs water in the air and gradually deliquesces. Its solubility in water is greater than that of sodium carbonate, and it is stronger than sodium carbonate. Use caution when using. The ratio of sodium carbonate to potassium carbonate is 1:0.77.
(2) Weak base. There is usually borax (Na2B4O7·102O). The latter is more alkaline than the former. They ionize in the hydrolyzate, but only a small fraction. When the PH value of the developer drops during use, they will again undergo ionization, so the stability of the PN value is maintained under certain conditions, which facilitates development.
(3) Strong alkali. Commonly used strong alkalis include sodium hydroxide (NaOH) and potassium hydroxide (KOH), also known as caustic soda and caustic potash, which are white crystalline blocks that are easily deliquescent in air, dissolve in water, and release a large amount of heat. Corrosion of the skin, should pay attention when using. At the same time, it should also be noted that closed storage to avoid reaction with CO2 in the air reduces the strongness of the alkali, and is often used in fast developing solutions that require a large contrast of the negative film. But the amount can not be too much, the liquid temperature can not be too high, or the film will produce a larger mask. Affect film transparency.
4. Inhibitors.
The commonly used inhibitor is potassium bromide (KBr). In addition, there are sodium bromide (NaBr), sodium chloride (NaCl), potassium iodide (KI), and the like. Both of them can improve the contrast on the negative image, reduce the blemishes, and can adjust the correct appearance of the strong light portion and the dark tone portion on the film. However, the use of too much, although the contrast can be enhanced, but the image level is very vulnerable. In the dots or small lines and text, the amount of potassium bromide is more than usual. However, it has a particularly large impact on Haidolin. The use amount is too much, and it appears to be too slow, because it suppresses the development characteristics of Hydex, and if it is used in excess, the developer will completely lose the developing effect.
Among the various chemical components of the developer, the developer is an easily oxidizable substance, and electrons are emitted due to its oxidation, so that the halogen silver obtains electrons to reduce the metallic silver, thereby achieving the purpose of development. Developers with strong stamina tend to ionize in the developer.
Benzene = phenol ionization such as:
Its comprehensive reaction in the developer is:
The role of the preservative is to prevent the developer from oxidizing when the developer is formulated or during storage. Especially Mitol, oxidation is rapid. Therefore, when prescribing drugs, a preservative should be added to control the chemical reaction of Mitol to oxygen.
Its reaction in the developer is as follows:
The resulting brewing after oxidation does not have a developing effect. The role of sulfite is to capture oxygen and prevent it from reacting with the developer so that the developer maintains the ionic development capabilities of the water.
Sodium sulphite not only prevents Haidigo from being oxidized, but also hydrates Haiduo, which has been oxidized after development, and produces a weak developer, hydroquinone sulphonate.
The role of the accelerator is to adjust the concentration of cerium ions in the developer and thereby control the ionization concentration of the developer. During the development process, the hydrogen ions released from the solution, if not controlled, will cause the concentration of hydrogen ions in the solution to continue to increase, so that the PH value will be significantly reduced, and the ionization rate of the developer will be significantly slowed, thereby seriously affecting the Development speed. The promoting effect of the alkali is that it is continuously neutralized with hydrogen ions to generate water, so that the developing ions in the developer maintain a stable concentration and the development proceeds normally. The chemical reaction is as follows:
The function of the inhibitor is to make halogen-free silver undeveloped. Because the potassium bromide ionizes in the solution, the Br (-) ions are absorbed in the photosensitive sheet where silver ions (Ag+) are present. We know that the development center is composed of metallic silver, so its ability to adsorb Br- is much smaller than that of the development center, so that there is no development center on the photosensitive film covered by Br-, and forms a negative charge barrier, repelling developing ions, So that the Ag+ can not be reduced to Ag. However, when the amount of potassium bromide is large, the concentration of Au ions is large, and the surface of the silver bromide around the development center may significantly change the developing speed due to excessive adsorption of bromide ions. Fifth, the fixing fluid composition and role In the exposure of the film after the fixing, sodium thiosulfate is generally used as a fixing agent, and anhydrous sodium sulfide to prevent the fixing solution oxidation. However, different films sometimes require different: At high temperatures, a hardener, potassium or chromium, is added to the acid fixer. Under normal circumstances may also not increase. Its formula is:
Sodium thiosulfate 250 g anhydrous sulfite 15 g acetic acid 45 ml potassium hydrazine 15 g water added to 1000 ml sodium thiosulfate fixing chemical reaction:
Since both dissolved Na3 [Ag(S2O3)2] and NaX are dissolved in water, development purposes are achieved.
Sodium thiosulfate
Exposure, the light energy acts on the halogen silver (AgX) crystal, halogen halide (X Ì„) in the silver will lose one electron from the halogen atom (X), as in Figure B, the reaction formula is as follows:
The generated free electrons form electrons that move in the crystal. When they meet the photosensitive center, they are attracted by the center, causing the center to bear a negative charge. When it encounters a negative electric field, it concentrates on the photosensitive center. It is neutralized into silver atoms. Just like:
(When the exposure amount of the photosensitive sheet reaches a certain level, the photosensitive center is enlarged and developed into a developing center due to the increase of silver, which is a basis for the latent image, so the halogen element is generated and is absorbed by the surrounding colloid. Second, the latent image is formed and transferred. To convert a latent image into a visible image, the silver atoms at the development center must continue to increase until the human eye can clearly observe it. This is accomplished through the action of development.
The purpose of the development is to reduce the silver ions of the silver salt molecules in the photosensitive layer emulsion layer to the silver atoms, which is the same as the exposure, but it is done by drugs. Therefore, the development can be regarded as the continuation of the exposure.
There are many drugs that can reduce halogen silver in development, and they are all easily oxidizable chemicals. The principle of development is described with respect to hydroquinone as an example. The hydroquinone is ionized in the developer as follows:
The anion is the imaging ion, which is easily oxidized to acid and emits two electrons.
Halide silver gets electrons reduced to silver.
The combined reaction of halogen ions and red ions to generate halothane is as follows:
Exposure has a light receiving portion and an unlighted portion, and the developer acts on the entire surface of the photosensitive layer, but why is only the halogen silver at the developing center reduced to silver? This is because potassium bromide is added to the developer and it ionizes Br in the solution. The development center is a silver atom, it is impossible to adsorb Br, only Ag+ will adsorb it. Therefore, in addition to the development center, they are all surrounded by Br, forming a negative barrier. In this way, the developing ions enter the crystal from the gap in the developing center, so that the silver halide is reduced to silver. Third, the stable visible image The finished image can clearly see the image, but the stability is poor, will disappear after seeing light, if stored in the developer, then the film will have no image, therefore, it is necessary to use chemical drugs The necessary processing can only meet the requirements. This process is called fixing.
The function of the fixing is to dissolve the unsolvated and undeveloped silver onto the photosensitive sheet, leaving only the reduced silver atoms. Fixers therefore require the ability to dissolve halogen silver without destroying the reduced silver. There are many agents belonging to this group, but some are toxic and some can stain the negative film. Therefore, sodium thiosulfate (Na2S2O3) is usually used. In special cases, ammonium thiosulfate [(NH4)2S2O3] can also be used. The chemical reaction is as follows:
Therefore, both Na3[Ag(S2O3)2] and NaX are dissolved in water. Thus, the purpose of development is achieved.
In the developer and fixer, there are not only the developer and the fixer, but also other chemical agents, and each has its own function, so we only have to understand their role and they are justified in dealing with various phenomena. Fourth, the composition of the developer and its role Developer.
Developers are drugs that reduce silver halides to silver, the most commonly used being Metol and Hydex. However, it is easily oxidized in water and should be used in conjunction with other drugs.
Mitoul is also known as Yilun, whose scientific name is methyl-p-aminophenol sulfate. The molecular structure is as follows:
It is a white or slightly grayish acicular or powdered crystal that dissolves at 4.8 grams per 100 ml of water at 10°C. It is hardly soluble in an aqueous solution of sulfurous acid, it is a strong developing agent with strong visualization. The image appears very quickly. When the developer is strong, it can appear in the developer for 2 seconds to 3 seconds. Its main feature is that it can make the dark part and the strong light image appear simultaneously, but The degree of difference between light and shade or black and white on the film is small, that is, the contrast is small. Compatible developer and sulfite coexist with good storage performance and low temperature response to potassium bromide. It is comparable to Hydrangeol to the same extent, making it difficult to contaminate negative film.
Haidolinji is also known as dinitrone. Its scientific name is called hydroquinone and its molecular structure is:
Its color is gray or white, usually fine needle crystals. It dissolves 6 grams per 1000 ml of water at 20°C, and its aqueous solution turns yellow easily because it is an easily oxidized material. In order to prevent oxidation, it has good developing performance, and generally it is necessary to dissolve sodium sulfite first in water, and then dissolve Haidolin. Hydergine development is slow. Especially for those parts where the exposure is particularly low, the effect is slight, but once the image appears, the density will increase rapidly, so the film is often dark or black and white. With high-contrast developing effect, when using Hadozicone, the pH value and temperature of the solution have a great influence on the shadow effect. Therefore, the developer should be developed at a certain temperature in order to achieve a stable purpose. . It must be developed in alkaline solution. It is better to use PH value in the range of 9.5---11. The larger the PH value is, the more alkaline it is, and the greater the density and contrast of the negative film. If the temperature of the developer is lower than 10°C, the development is very slow. When the temperature is low, the developing effect is hardly developed. However, if the temperature is higher than 20°C, the development is quick, but the negative film is liable to be flawed. Back to this, when used, the temperature should be in a relatively stable range. It is often used in combination with Methocel to achieve correct development purposes. When combined with Metol, they are called M--Q. .
2. Preservatives.
The preservative is usually sodium sulfite, also known as sulphur oxide powder, and its function is to prevent the oxidation of mitel. There are two kinds of anhydrous and crystalline. Its molecular formula is Na2SO3 (anhydrous sodium sulfite) and Na2SO3 · 7H2O (crystalline). Colorless white powder, relatively stable in air; crystallized as white granules, easily oxidized into sodium sulphate in the air, so it should be sealed and stored, both can be used when used, but should pay attention to the amount, if not For 1 g of water, 2 g of crystalline was used because the molecular weight of anhydrous was 126 and the molecular weight of the crystalline was 252, which was exactly twice that of anhydrous. In the existing circumstances, we often use anhydrous to facilitate the preservation of the developer. Generally, when the temperature is high, the amount can be increased appropriately to increase the image contrast, but too much is not good for the quality of the negative film, and the halogen silver in the negative film is easily dissolved. Therefore, it is often required that the developer has a stable temperature.
3. Accelerator.
Accelerators are all alkaline substances. Usually there are 3 types of strong bases, weak bases and soft bases. Soft bases are commonly used.
(l) Soft Base. Soft alkali is mainly composed of sodium carbonate (Na2CO3) and potassium carbonate (K2CO3), and its aqueous solution has a PH value of 10.8. Alkaline is weaker. There are three kinds of anhydrous sodium carbonate, one water (Na2CO3 · H2O) and crystal (Na2CO3 · 10H2O), all of which can be used. The amount ratio of the sodium carbonate is: anhydrous: water: crystallization = 1:1.17:2.7. When the temperature is high, the dosage should be reduced appropriately. When the amount is too large, the negative film can be easily generated and the quality of the negative film can be affected. Potassium carbonate easily absorbs water in the air and gradually deliquesces. Its solubility in water is greater than that of sodium carbonate, and it is stronger than sodium carbonate. Use caution when using. The ratio of sodium carbonate to potassium carbonate is 1:0.77.
(2) Weak base. There is usually borax (Na2B4O7·102O). The latter is more alkaline than the former. They ionize in the hydrolyzate, but only a small fraction. When the PH value of the developer drops during use, they will again undergo ionization, so the stability of the PN value is maintained under certain conditions, which facilitates development.
(3) Strong alkali. Commonly used strong alkalis include sodium hydroxide (NaOH) and potassium hydroxide (KOH), also known as caustic soda and caustic potash, which are white crystalline blocks that are easily deliquescent in air, dissolve in water, and release a large amount of heat. Corrosion of the skin, should pay attention when using. At the same time, it should also be noted that closed storage to avoid reaction with CO2 in the air reduces the strongness of the alkali, and is often used in fast developing solutions that require a large contrast of the negative film. But the amount can not be too much, the liquid temperature can not be too high, or the film will produce a larger mask. Affect film transparency.
4. Inhibitors.
The commonly used inhibitor is potassium bromide (KBr). In addition, there are sodium bromide (NaBr), sodium chloride (NaCl), potassium iodide (KI), and the like. Both of them can improve the contrast on the negative image, reduce the blemishes, and can adjust the correct appearance of the strong light portion and the dark tone portion on the film. However, the use of too much, although the contrast can be enhanced, but the image level is very vulnerable. In the dots or small lines and text, the amount of potassium bromide is more than usual. However, it has a particularly large impact on Haidolin. The use amount is too much, and it appears to be too slow, because it suppresses the development characteristics of Hydex, and if it is used in excess, the developer will completely lose the developing effect.
Among the various chemical components of the developer, the developer is an easily oxidizable substance, and electrons are emitted due to its oxidation, so that the halogen silver obtains electrons to reduce the metallic silver, thereby achieving the purpose of development. Developers with strong stamina tend to ionize in the developer.
Benzene = phenol ionization such as:
Its comprehensive reaction in the developer is:
The role of the preservative is to prevent the developer from oxidizing when the developer is formulated or during storage. Especially Mitol, oxidation is rapid. Therefore, when prescribing drugs, a preservative should be added to control the chemical reaction of Mitol to oxygen.
Its reaction in the developer is as follows:
The resulting brewing after oxidation does not have a developing effect. The role of sulfite is to capture oxygen and prevent it from reacting with the developer so that the developer maintains the ionic development capabilities of the water.
Sodium sulphite not only prevents Haidigo from being oxidized, but also hydrates Haiduo, which has been oxidized after development, and produces a weak developer, hydroquinone sulphonate.
The role of the accelerator is to adjust the concentration of cerium ions in the developer and thereby control the ionization concentration of the developer. During the development process, the hydrogen ions released from the solution, if not controlled, will cause the concentration of hydrogen ions in the solution to continue to increase, so that the PH value will be significantly reduced, and the ionization rate of the developer will be significantly slowed, thereby seriously affecting the Development speed. The promoting effect of the alkali is that it is continuously neutralized with hydrogen ions to generate water, so that the developing ions in the developer maintain a stable concentration and the development proceeds normally. The chemical reaction is as follows:
The function of the inhibitor is to make halogen-free silver undeveloped. Because the potassium bromide ionizes in the solution, the Br (-) ions are absorbed in the photosensitive sheet where silver ions (Ag+) are present. We know that the development center is composed of metallic silver, so its ability to adsorb Br- is much smaller than that of the development center, so that there is no development center on the photosensitive film covered by Br-, and forms a negative charge barrier, repelling developing ions, So that the Ag+ can not be reduced to Ag. However, when the amount of potassium bromide is large, the concentration of Au ions is large, and the surface of the silver bromide around the development center may significantly change the developing speed due to excessive adsorption of bromide ions. Fifth, the fixing fluid composition and role In the exposure of the film after the fixing, sodium thiosulfate is generally used as a fixing agent, and anhydrous sodium sulfide to prevent the fixing solution oxidation. However, different films sometimes require different: At high temperatures, a hardener, potassium or chromium, is added to the acid fixer. Under normal circumstances may also not increase. Its formula is:
Sodium thiosulfate 250 g anhydrous sulfite 15 g acetic acid 45 ml potassium hydrazine 15 g water added to 1000 ml sodium thiosulfate fixing chemical reaction:
Since both dissolved Na3 [Ag(S2O3)2] and NaX are dissolved in water, development purposes are achieved.
Sodium thiosulfate
Outdoor Sofas Furniture
Sofas furniture that is three seat seat, you can sit together with your friends or family together, or lie down for a lunch rest. Completely comfortable sofas furniture are perfect fit for arid and coastal climates alike.
· Handwoven premium resin wicker UV resistant
· Rust-resistant powder-coated frames
· Cushions included with 30 density sofa foam
· Versatile tempered glass tables
· Cushions also available with 100% waterproof fabric.
Outdoor Sofas furniture with different style and hand weaving
If you have any questions, please contact with us directly. Outdoor Sofa Furniture are produced
by Golden Eagle Outdoor Furniture With High Quality and Good Appearance. Welcome you can visit our Factory.For any inquiry,Please send mail directly to us.
Sofas Furniture
Aluminum Patio Furniture,Garden Furniture Cushions,Contemporary Outdoor Furniture,Garden Outdoor Furniture PE Wicker
Golden Eagle Outdoor Furniture Co., LTD. , http://www.geoutdoor.com