Changed CTP Plate Performance

Effectively improve the performance of CTP media, reduce its cost, meet the requirements of various customers, and ultimately will occupy the mainstream position of the lithography. There are various methods for CTP, and the wet-developed plate is required as it is in the existing PS plate. It has been used first. During the development process, management is important to ensure the quality of the printing plate. Accompanying developer preparation, developing operation, waste management/waste sheet processing, and developing device cleaning, the burden on the work environment will increase. The abolition of the development process is not only for the purpose of stabilizing the quality of the printing plate, but also for responding to the call from the eco-environmental department to reduce non-renewable waste, while also improving the working environment. Therefore, it is necessary to develop and develop a plate that does not require wet development. Moreover, starting from the new market demand, it is also necessary to develop and develop non-developed plates to meet new needs.

The biggest technical problem in the development of CTP is how to form a non-graphical part with high printing capacity. The blank part of the currently used PS plate relies on the formation of sand on the surface of the aluminum plate after grinding, anodization, or further hydrophilization. In addition, there is a non-aluminum-based silver salt diffusion method (need wet development), the hydrophilicity of which is formed using gelatin or a polymer material coated on the surface of gelatin. The phase change method generally seeks hydrophilic parts that are not related to aluminum plates. Therefore, according to different uses of plastics, water-resistant paper, etc., the plate base material is more selective.

1. There are many known hydrophilic functional groups of chemically modified lithographic printing methods.

The chemical change method refers to a photochemical reaction mode caused by light irradiation, or a heat reaction mode caused by converting the absorbed light into heat energy. Do not use the thermal reaction (thermal-sensitivity CTP) for the most publicly disclosed plates. Specifically, a photothermal conversion dye capable of absorbing laser light energy is added to the recording layer, and the irradiated light energy is converted into heat energy. The laser in the near-infrared wavelength range near 800 to 1060 nm is generally used. The chemically modified CTP plate has a negative pattern converted into a lipophilic part by a laser irradiation and a positive pattern converted into a hydrophilic one.

(1) Negative version

Negative-graphic version means that the exposed part is lipophilic, and the unexposed part is hydrophilic. After exposure, it turns into lipophilicity. The non-photosensitive hydrophilic layer may be an organic compound that forms a water-soluble film, a metal surface, a monomer/polymer organic acid (or inorganic acid), an organic acid/inorganic acid salt, etc., and absorbs light energy in the hydrophilic layer. The material forms the recording layer. The exposed portion of the recording layer becomes hydrophobic, intrinsic and insoluble in water. This is due to the polymerization or bridging reaction of some of the molecules of the recording layer irradiated by the laser, and the hydrophilic group -OH is decomposed or becomes a hydrophobic group. The results of the printing test show that the resistance to imprint can reach 1 to 35,000 impressions.

The urea or the initial condensate of melamine and formaldehyde forms a hydrophilic layer on the surface of the substrate and can be used as a plate for printing. This type of plate does not use laser for printing, and the heated stylus directly depicts the graphic on the hydrophilic layer, and the printing effect is good. The use of CTP is not clear. If a photothermal conversion dye is used, it may become a CTP plate.

A plate produced by thermal decomposition of sulfonic acid. This plate is used to introduce sulfonic acid groups into plastic structures (such as sulfonated polyethylene). When heated with a stylus or laser, the sulfonic acid groups in the light receiving/heating part undergo decomposition reactions and become lipophilic. Report.

(2) Positive chart version

The positive version refers to the exposed portion becoming hydrophilic and the unexposed portion remains oleophilic to accept the ink. The heat sensitive film is a flat printing plate that is heated to make it more hydrophilic without the need for dissolution treatment. Using a carboxylic acid ester that is easily decomposed in an acidic solution, the carboxylic acid ester absorbs light energy to generate heat, and the acid produced by heat/light acts as a catalyst to eventually produce a carboxylic acid to have hydrophilicity. This technology is the same as the principle of making semiconductor resist materials.

Using the current PS plate as a support, it is possible to produce a plate that does not require wet development, and it is also possible to make a wet plate that is the same as the current PS plate. Laser printing and printing test results are all displayed. From the principle of the carboxy acid inducer used by 3M Corporation, the hydrophilic group is introduced into the recording layer, and it loses its hydrophilicity, and it is restored to the original hydrophilic material upon irradiation with laser light, and is used as a CTP plate that is not developed. Material will also appear.

(3) Positive and Negative Graphs Dual-Use Types: Utilization of Metal Oxides The above describes the hydrophilic and lipophilic technologies that focus on the Palace Energy Group. Using the characteristics of the hydrophilic and lipophilic elements formed by the photochemical reaction of metal oxides and their different oxidation states, it is also possible to produce a plate that is not developed. Recently, elimination and: renewable CTP plates have also been developed. Titanium oxide is hydrophobic in the dark and becomes hydrophilic when exposed to ultraviolet light. With this characteristic of titanium oxide, a plate that is not developed can be made. It is also possible to produce a printing apparatus that forms a latent image recording layer on a machine with titanium oxide as a main component. After printing, the plate is washed and reheated to a predetermined temperature, and it can be recycled.

2, composition changes

The feature of the composition change type is to keep the hydrophilic material and the lipophilic material in the recording layer in a separated state, break their separation state under irradiation of laser light, and make the surface of the recording layer hydrophilic and intimacy. This method began when the thermal recording head was used as a recording means. There are mainly two methods: First, the particulate lipophilic substances are dispersed in the hydrophilic substance so that the two substances are kept in separate states. First, the hydrophilic substance and the lipophilic substance are layered and coated to form a multilayer structure.

The recording layer can also be produced by encapsulating a photopolymerizable monomer, a photosensitive resin, and a UV curing catalyst in a hydrophilic surface layer and applying it to a substrate. After the laser is used to heat the print, it is cured by proper light irradiation. In the unprinted part of the microcapsules, a polymerization reaction occurs and the hardening occurs. The printed part of the microcapsules releases a photosensitive substance and sees light and hardens to form lipophilicity.

The microcapsule is composed of a hydrophilic polymer film-forming agent that includes a bridging function and an oleophilic material that can react with it. This type of plate material causes the macromolecule film forming agent to chemically react with a graphic portion released by heating during printing to form lipophilicity, and the image-resistance due to bridging reaction results in high printing force.

A plate in which a hydrophilic and oleophilic material is separated and uniformly mixed in a recording layer using a microcapsule: a recording layer composed of an inorganic pigment, a film former, and a wax, and an expansive capsule containing propane, butane, and light Heat transfer agents (pigment, carbon black) are dispersed therein.

On the hydrophilic material layer, a lithographic plate formed by applying a sol-gel layer is used, and inorganic fine particles, inorganic pigments, and the like are used.

3, liquid crystal array change type

Using the characteristics of the liquid crystal alignment method, a flat printing plate for multi-recording and a plate-making integrated printing apparatus using such a plate (a type of CTPress) are manufactured. This plate utilizes the hydrophilic and oleophilic properties of the surface of the polymer liquid crystal compound due to the different arrangement states. Instability can become hydrophilic under the effect of heat.

Morphological change method The CTP form change method is similar to the phase change method. Here we mainly introduce the CTP plate material technology based on the change of surface roughness. The unpolished aluminum plate surface is scanned with a laser to roughen it to form a non-developed plate material that is not imaged. The type of laser printing has not yet been disclosed. In contrast, the surface of the aluminum plate having a sand day is irradiated with a CO 2 laser so that the rough surface becomes a smooth surface and forms lipophilicity. After processing, the number of imprints on the offset printing press is about 1,000 impressions.

The non-graphical parts of the above two methods all depend on the rough part of the layout. From this, it can be seen that the aluminum plate with a relatively high hydrophilicity in the metal is more hydrophilic than the aluminum plate without surface treatment. In addition to this, there are other CTP plates that are not developed with heat energy generated by laser irradiation to change the surface smoothness. For example, the surface-roughened polytetrafluoroethylene is heated by laser scanning to make its surface tear-free and turn into a lipophilic technique. The transfer temperature of 50 ~ 100 °C thermoplastic resin and silicone rubber layer is fixed on the plate material, and then made of polyester protective layer, the surface of the light receiving part after laser irradiation becomes concave and convex to form a oleophilic plate material. Specific crystalline polymer materials such as fluorinated vinylidene and trifluoroethylene have different degrees of crystallinity when rapidly cooled or gradually cooled, and the smoothness (roughness) of the surface is not a problem. Using this property, a flat printing plate material can be produced.

Source: Coinprint