JPH0461789B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel image forming method that can be easily carried out in a bright room. Conventionally, silver salt films and sensitizers using organic photosensitizers such as diazo have been widely used for forming positive and negative images, but silver salt films, of course, cannot be handled in a bright room. Even with organic photosensitizers that are said to be possible, they cannot be handled freely in general indoor work, and there are significant operational restrictions. On the other hand, with the rapid progress of electrical and optical signal conversion technology, methods of converting electrically transmitted information or information stored in a computer into optical signals and forming images without camera work are also being developed, including plate making and electronic circuit creation. There is a need for an inexpensive image forming method suitable for such systems. As a result of intensive studies to address the above-mentioned problems, the inventors of the present invention have developed a recording layer coating mainly composed of a particulate resin whose surface is hydrophilic and whose interior is hydrophobic. The present inventors have now completed the present invention by discovering that a novel image forming method can be obtained that allows image formation to be carried out freely in a room environment and does not require the use of expensive materials such as silver salts or organic photosensitizers. That is, in the present invention, an aqueous dispersion coating containing (a) a colorant and (b) a particulate resin whose surface is hydrophilic and whose interior is hydrophobic is applied onto a support substrate, and the particulate resin is a recording layer coating forming step in which a recording layer coating is formed by drying while maintaining the particle morphology; and a predetermined portion of the recording layer coating corresponding to a desired image pattern is heated to eliminate the particle morphology. A fixing step in which the image pattern is fixed on the support substrate; and a developing step in which the recording layer coating film on which the image pattern is fixed is treated with an alkaline aqueous solution and the non-heated portions of the coating film are peeled off and removed. The image forming method is a constituent element. Hereinafter, the constituent elements of the present invention will be explained in detail together with its effects. The coloring agent (a) used in the present invention is used to color the fixed part of the coating film corresponding to the image pattern in a specific color so that the part can be visually identified, and in some cases, to color the fixed part of the coating film in a specific color. It also has a light-shielding function of absorbing light of specific wavelengths in the visible and infrared regions, allowing the formed image to be used as a positive film or a negative film. Further, when an exposure light source as described below is used as a heating heat source in the fixing process, it is made to also function as a sensitizer in converting absorbed light into heat. Examples of such colorants include carbon colorants such as carbon black and graphite powder, metal oxides such as titanium oxide, iron oxide, zinc oxide, chromium oxide, molybdenum oxide, tellurium oxide, alumina, and silica, and yellow. Gold salts such as lead, barium sulfate, calcium oxide, ultramarine, and cadmium sulfide, fine metal powders such as iron, chromium, manganese, cobalt, aluminum, copper, and zinc, organic pigments such as phthalocyanine blue and phthalocyanine green, and acid dyes. , basic dyes, disperse dyes, fluorescent dyes, etc.
Without being limited to these examples, any colorant may be used in a discernible amount as long as the imaged area can be identified in the fixing and developing steps of the present invention. It is preferable that the above-mentioned colorant is uniformly distributed in the planar and longitudinal directions in the recording layer coating film of the present invention, so it is preferable that the colorant dissolves in the aqueous dispersion coating, or if it does not dissolve, it disperses without agglomerating. From this point of view, when a colorant is used as the latter dispersion state, the average particle size is preferably 1 μm or less, more preferably 0.1 μm.
It is more preferable that it is below. Colorants have the ability to absorb light at specific wavelengths, such as the visible region (including near-infrared and near-ultraviolet regions), and use the light-shielding function for that wavelength to transfer images formed onto positive or negative film. It can be applied. In such cases, the type and amount of colorant to be used is selected depending on the desired absorption wavelength and amount of absorbed light, and the amount of colorant used is usually 0.1 to 50% by weight based on the resin component in the recording layer.
Preferably it is about 1 to 50% by weight. Among the above colorants, carbon colorants such as carbon black and graphite powder and fine metal powders (usually have an average particle size of 1000 mm or less) absorb light in the near-infrared region. Since it generates heat by absorbing light, it not only functions as a light-shielding agent for identification and image areas, but also acts as a sensitizer that enables fixing by light. The sensitizer function of such a colorant is hardly necessary when using laser light as a light source;
For example, it is useful when using a xenon lamp light source. Generally, to impart such a function, the above-mentioned colorant is generally used in an amount of 5 to 50% by weight based on the resin component in the recording layer. In the present invention, the supporting substrate on which the recording layer coating is to be formed is a sheet or film that can be arbitrarily selected depending on the intended use. That is, when using this film as a positive film or a negative film, various transparent plastic films such as polyester, polycarbonate, polystyrene, polymethacrylate, cellulose acetate, polyamide, polyimide, polyarylate, and polysulfone are useful, but fixing Glass transition temperature or primary transition temperature that does not cause thermal deformation during heating in the process is 80℃
The above plastics are preferable. In addition, an image is formed on a metal plate such as aluminum and used as an offset printing original plate, or an image is formed on a metal plate such as copper or aluminum or a material laminated with metal foil and the image part is etched, plated, etc. It can also be used as a material. In order to improve the adhesion with the recording layer coating, the supporting substrate may be subjected to primer treatment, surface roughening treatment, or activation treatment. In the present invention, an aqueous dispersion paint containing as main components (a) the colorant and (b) a particulate resin whose surface is hydrophilic and whose interior is hydrophobic is applied onto a support substrate. Such a particulate resin can be obtained by using a hydrophobic vinyl monomer in combination with a hydrophilic monomer that imparts hydrophilicity to the surface, or by emulsion polymerization in the presence of a water-soluble resin. Usually this is 0.05~0.8μ
Since it is obtained as an aqueous dispersion having a particle size of about m, the dispersion can be used as it is as an aqueous dispersion paint by adding a colorant and appropriately diluting it. Incidentally, the particle size of the resin particles is not limited to the above-mentioned range, and may of course be smaller than or larger than this range. The hydrophobic vinyl monomer used here is
For example, methyl acrylate, ethyl acrylate,
Acrylic acid esters such as propyl acrylate, butyl acrylate, octyl acrylate, cyclohexyl acrylate, benzyl acrylate, methoxyethyl acrylate, glycidyl acrylate;
Methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, octyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, benzyl methacrylate,
Methacrylic acid esters such as methoxyethyl methacrylate, butoxyethyl methacrylate, glycidyl methacrylate; styrene, vinyltoluene,
Aromatic vinyl monomers such as paramethylstyrene, α-methylstyrene, and parachlorostyrene; Halogen-containing vinyl monomers such as vinyl chloride and vinylidene chloride; Unsaturated nitriles such as acrylonitrile and methacrylonitrile; dimethyl fumarate , diesters of unsaturated dibasic acids such as dibutyl fumarate, dimethyl itaconate, dibutyl itaconate, dioctyl itaconate, and dicyclohexyl itaconate. In addition, examples of the hydrophilic monomer used in the present invention include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, and maleic anhydride; monomethyl fumarate, monobutyl itaconate, and monoethyl maleate. Monoesters of unsaturated dibasic acids such as; hydroxy-containing unsaturated monomers such as hydroxyethyl acrylate and hydroxyethyl methacrylate; unsaturated amides such as acrylamide, methacrylamide, and methylolacrylamide are used; The proportion of hydrophilic monomers in the total monomers is 0.5 to 8% by weight, particularly preferably 1 to 5% by weight. Note that when emulsion polymerization is carried out in the presence of a water-soluble resin described below, the use of the above-mentioned hydrophilic monomer is not an essential requirement. The aqueous dispersion paint obtained as described above is usually coated on a supporting substrate by any method such as roll coating, spin coating, spraying, dipping, etc.
It is applied to a dry coating thickness of ~100 μm, preferably 3 to 30 μm. In the present invention, the aqueous dispersion coating coated on the supporting substrate is dried to form a recording layer coating while maintaining the particle form of the particulate resin in the coating. For this purpose, the drying is carried out at room temperature or at a forced heating temperature within a range where the particulate resins do not fuse or fuse with each other and lose their particle form. This condition is usually satisfied by setting the temperature of the forced heating below the glass transition point of the particulate resin and evaporating the dispersion medium at a temperature within this range. Therefore, from the above requirements regarding the drying temperature,
The glass transition point of the resin is 40°C or higher, preferably 50°C.
It is desirable that the temperature be at least 0.degree. C., and the selection of monomers must also take this point into consideration. In addition, in order to ensure that the particulate resin further maintains the particulate form as specified in the present invention, for example,
A small amount of so-called polyvalent vinyl oligomers such as divinylbenzene, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and polypropylene glycol dimethacrylate, and dienes such as butadiene and isoprene may be copolymerized with the above monomers. In the present invention, the recording layer coating film formed as described above (corresponding to the desired image pattern) is
By heating a predetermined portion to fuse and fuse the particles with each other, the particle shape disappears, and the particles are fixed together with the colorant on the support substrate. This is the fixing process. In this fixing process, various heat sources can be used to heat and fix a predetermined area, such as a thermal pen, high frequency heating, or electrical heating between opposing voltages. For example, a YAG laser can be used. Exposure can be carried out by directing light to the desired area and fixing it with the heat generated by the absorption of laser light, by using a xenon lamp light source, passing it through a photomask, or by using the light reflected from the original. A method of fixing using heat generated by light absorption in the exposed area is particularly preferred from the viewpoint of forming a fine image pattern. After the fixing step, the recording layer coating film is treated with an alkaline aqueous solution, and the non-heated portions of the coating film are peeled off to form an image pattern on the supporting substrate.
This is the developing process. That is, due to the heating operation in the fixing process, the particulate resin in the heated part loses its particle form, fuses and firmly adheres to the supporting substrate, and since the inside of the particle is hydrophobic, this part is exposed to an alkaline aqueous solution due to the fusion. In contrast, in the non-heated part, individual particles exist while maintaining their particle morphology.
Moreover, since the surface of each particulate resin is hydrophilic, it can be easily peeled off and removed from the supporting substrate by treatment with an alkaline aqueous solution. Examples of alkaline aqueous solutions include caustic soda, caustic potash, soda carbonate,
Alkaline aqueous solution such as potassium carbonate, or, for example, triethylamine, triethanolamine,
Aqueous amine solutions such as dimethylethanolamine and ammonia are used. In a further preferred embodiment of the present invention, a hydrophilic resin is interposed between particulate resins in the recording layer coating so as to form a substantially continuous phase. When a recording layer coating film is formed using only a particulate resin as a main component, the recording layer coating film may sometimes fall off from the support substrate. 〓
By interposing the particles, it is possible to more reliably bind the particles to each other and the particles to the supporting substrate. Any means may be adopted for this purpose, but
For example, a method of mixing a carboxyl-containing water-soluble resin such as a water-soluble acrylic resin or a styrene maleic acid resin, or emulsion polymerization of the above-mentioned monomer groups in the presence of a carboxyl-containing water-soluble resin such as a so-called protective colloid emulsion. Particularly preferred is a method in which a particulate resin aqueous dispersion in which the particle interface is covered with a water-soluble resin is used. However, if the amount of the above water-soluble resin component increases too much,
Even the parts fixed by heating tend to peel off due to the phenomenon caused by aqueous alkaline solutions, so at least 60% by weight of the total resin component, especially
Preferably, 70% to 90% by weight is particulate resin. Incidentally, a small amount of auxiliary agents such as an organic solvent, a leveling agent, and an antifoaming agent may be added to the water-dispersed paint. As described above, the image forming method of the present invention can be carried out in a completely bright room, and is an inexpensive method that does not require silver salts or special photosensitizers. It can be widely applied to The present invention will be specifically explained using examples, but these are merely illustrative and the technical scope of the present invention (Article 70 of the Patent Law) should be construed as being limited by these examples. must not. Examples and Comparative Examples (a) Production of particulate resin (1); In a reactor equipped with a stirrer, 68 parts by weight of deionized water, water-soluble acrylic resin () (methyl methacrylate 50 parts by weight)
wt%, styrene 20 wt%, hydroxyethyl methacrylate 15 wt%, ammonium acrylate 15
60 parts by weight of a 25% aqueous solution of copolymer) and 0.5 parts by weight of potassium persulfate were placed in a reactor and heated to 70°C.
After raising the temperature to The particle surface is covered with a hydrophilic resin and the inside of the particle is hydrophobic by polymerizing by continuously dropping the resin at the same temperature for 3 hours (A). ,
(B) and (C) were obtained. The resin solid content, viscosity, and glass transition point (measured by DSC method) of the resins (A), (B), and (C) are also listed in Table 1. (b) Production of particulate resin (2); 100 parts by weight of deionized water in a reactor equipped with a stirrer;
Charge 0.5 parts by weight of potassium persulfate and 0.1 parts by weight of sodium alkylbenzenesulfonate into the reactor.
After raising the temperature to 70℃, (D), (E), (F) shown in Table 2,
An emulsion consisting of the monomer raw materials (G) and (H), tertiary decyl mercaptan, sodium alkylbenzenesulfonate, and deionized water was continuously added dropwise over a period of 5 hours, and after the addition was completed, the emulsion was continued at the same temperature. Polymerization was carried out by keeping it for 3 hours for (D) without adding a water-soluble resin, and (E), (F), (G), and (H) in the first stage.
The aforementioned water-soluble acrylic resin () or water-soluble acrylic resin () (styrene 40% by weight,
A 25% aqueous solution of a copolymer of 40% by weight of butyl acrylate, 15% by weight of itaconic acid monobutyl ester, and 5% by weight of maleic anhydride neutralized with dimethylethanolamine was added to each particle to make the surface hydrophilic. Aqueous dispersions (D), (E), (F), (G) and (H) of particulate resins having hydrophobic particle interiors were obtained. Resin solid content of (D), (E), (F), (G) and (H),
The viscosity and the glass transition point (according to the DSC method) of the particulate resin before addition of the water-soluble acrylic resin are
It is listed in the table. (c) Production of colored water-dispersed paint and formation of recording layer coating; 100 parts by weight of the aqueous dispersion of each of the particulate resins described in (A) to (H) above was adjusted to pH 7.5-8.0 with ammonia. ,
Put 10 parts by weight of carbon black into a sand mill.8
A colored paste is made by dispersing it for a while, and then an aqueous dispersion of particulate resin is added and mixed so that the weight ratio of resin solid content and carbon black is 100:5, and then filtered through a cartridge type filter. Each colored water-dispersed paint was obtained. Each water-dispersed paint corresponding to (A) to (H) was diluted with water to adjust the viscosity to 200 to 400 CPS, and then applied to a 75μ polyester film to a dry film thickness of approximately 10μ. It was dried for 1 hour in a hot air drying oven at .degree. C. to remove water by evaporation, and a black opaque (that is, completely light-shielding) recording layer coating was formed on the polyester support substrate as shown in FIG.

【table】 All raw material numbers in the table are parts by weight.

[Table] All values for raw materials in the table are parts by weight.
(d) Evaluation of image formation; Regarding each of the above recording layer coatings corresponding to the particulate water dispersions (A) to (H), first check the adhesion to the polyester support by rubbing with gauze to see if there is any peeling. It was determined by Next, a spot beam (beam diameter a = 50 μm) of a YAG laser (output 0.3 W) was applied to each recording layer coating film at a distance of 20 cm/20 cm according to pattern A shown in Figure 2.
The exposed area was fixed on the supporting substrate by scanning at a speed of 1.5 sec, and then it was immersed in a 5% aqueous solution of sodium carbonate and developed by lightly rubbing the surface with a nylon brush, as shown in Figure 3. An image pattern was obtained. Here, A is the fixed light-shielding image pattern (exposed area), and B is the area where the recording layer coating has been completely peeled off and the surface of the transparent polyester support base is exposed (unexposed area). shows. The image formability of this image pattern was evaluated by examining the presence or absence of peeling in unexposed areas and exposed areas. The evaluation results are listed in Table 3. Note that (A), (B), (D), (E), (F), and (G) are examples of the present invention, and (C) and (H) are comparative examples.

【table】

【table】 [Brief explanation of the drawing]

1 to 3 are plan views showing the recording layer coating film of the present invention. In the figure, Figure 1 is before exposure;
FIG. 2 shows the state during exposure (fixing step), and FIG. 3 shows the state after development. Also, a=50μm, b=30
mm, c=25mm, d=20mm, e=15mm, f=10mm,
g=5mm.

Claims (1)

[Claims] 1. (a) the colorant and (b) the surface are hydrophilic;
Forming a recording layer coating film by coating a water-based dispersion coating material containing a particulate resin with a hydrophobic interior on a supporting substrate and drying the particulate resin while maintaining its particle form to form a recording layer coating film. a fixing step of heating a predetermined portion of the recording layer coating corresponding to a desired image pattern to eliminate the particle morphology and fixing it together with a colorant on a supporting substrate; An image forming method comprising the steps of treating a coating film with an alkaline aqueous solution and peeling off and removing non-heated areas of the coating film.