JPH0418297B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for matting the front and/or back side of a recording material. Conventionally, there have been a wide variety of techniques for manufacturing recording materials, one of which is to make the front and back surfaces of photographic light-sensitive materials matte to prevent static electricity, prevent adhesion between photographic light-sensitive materials, and improve vacuum adhesion. is being carried out. For example, when conventionally, when forming an image on a photographic light-sensitive material, a film original plate is placed on the photosensitive material in the exposure process, and when exposure is carried out through the film original plate, the surface of the photosensitive layer of the photosensitive material is It is necessary to expose the stacked film originals in such a way that they are brought into perfect contact with each other to avoid blurring of the exposed image due to gaps between them. For this reason, generally, a vacuum printing frame is used, and the photosensitive material and film original are stacked and placed between the glass plate and rubber sheet of the printing frame, and a vacuum is created between the glass plate and the rubber sheet to bring them into close contact. A method (hereinafter referred to as the vacuum contact method) has been used;
As described in Japanese Patent Application No. 111102, it was thought and implemented to make the photosensitive layer matte and significantly shorten the vacuum adhesion time by providing a fine pattern consisting of coated and uncoated areas on the photosensitive layer. The formation of minute patterns (matting) on the photographic photosensitive layer is described in, for example, Japanese Patent Application Laid-Open No. 51-96604, Japanese Patent Application Laid-Open No. 51-98505, and Japanese Patent Application Laid-Open No. 55-12974. There is a way. In recent years, so-called double-sided photographic materials, in which photosensitive layers are provided on both sides of the support, have become extremely popular among photographic materials. As described in , when trying to provide a micropattern on the surfaces of both photosensitive layers using the gravure coating method, the micropattern is first applied to one side, dried, and then the micropattern is applied to the other side. It has to be dried, and this series of equipment becomes quite large-scale. Moreover, the part where the micropattern is applied on the back side provided by the above method is not used in the process until it is cut to the desired size. It is often rubbed by conveying rollers and peeled or crushed, and when image exposure is performed on the photosensitive layer on the back side, the vacuum adhesion time is longer than that on the front side. In addition, in the exposure process, there is a problem that the applied part of the micro pattern on the back side, which will be exposed later, is compressed and crushed by the printer during vacuum exposure on the front side, and it takes a long time to vacuum when exposing the back side. Ta. Also, JP-A-51-
Publication No. 98505 discloses that in order to solve the problem that the coating layer for improving vacuum adhesion stains the original film, a wax-like or fine powder resin with mold releasability is dispersed in a low boiling point organic solvent and air sprayed. A coating method is shown, but this coating layer has a weak adhesion to the surface of the photosensitive printing plate, so it easily falls off.
As expected, there were the same problems as mentioned above. Moreover, the use of organic solvents is not preferable from the viewpoint of safety during production. Furthermore, JP-A-55-12974 discloses a method of spreading solid powder and fixing it onto a photosensitive printing plate using heat. There is a problem in that the mat layer on one side is crushed when it is conveyed by rollers after it has been placed and before it is cooled, and on the other hand, it is difficult to convey it without using rollers.
Another drawback was that the resin had to be crushed and dispersed in order to make powder, resulting in high costs. Furthermore, JP-A-55-101951 discloses a method for uniformly dispersing solid powder onto the surface of a continuously running photosensitive printing plate, but it requires a pressurized air supply device, a powder supply device, an ejector, and a distributor. viewer,
A cyclone or the like is required, and the device is quite complex and large-scale. Moreover, in the case of a double-sided type photosensitive printing plate, there is a drawback that the solid powder tends to fall off when the photosensitive printing plate is transported after being simultaneously attached with solid powder. In order to solve these problems,
Publication No. 34558 discloses a method in which an aqueous liquid in which a resin is dissolved or dispersed is sprayed onto the surface of a photosensitive printing plate having a photosensitive layer on a support, and then dried. Although the performance of the mat is very good in this method, there are some difficulties in terms of suitability for production. In other words, when using air spray, the adhesion rate of fine droplets is very low (about 10%), so
The unattached droplets contaminate the inside of the coating chamber as overspray, and in extreme cases, they end up adhering to the plate being coated as unnecessary resin lumps. To reduce this overspray, an electrostatic coating method can be considered (adhesion rate approximately 90%).
%that's all). However, when applying an aqueous liquid by electrostatic coating, there are the following problems. First, in the case of the electrostatic coating method, fine droplets are electrostatically attached to the surface of the object to be coated, so it is impossible to make strong contact with the surface of the object to be coated, for example, especially when it is atomized and then it dries before it adheres. Very small particles have a small contact area and weak adhesion, and in the extreme, they end up merely being electrostatically attached to the surface. As a result, if the photosensitive material is conveyed while being in contact with a roll or the like, the adhered particles will fall off, making it impossible to achieve the desired shortening of the vacuum adhesion time, and the film original or conveyance roller This results in contamination. Furthermore, in the case of a bell type or a disc type, the aqueous liquid dries in areas where the liquid flow of the thin film on the bell or disc is poor, resulting in the resin precipitating, which may impede atomization or cause the precipitated resin to be covered. It may adhere to painted objects. These are examples of improving the vacuum adhesion of photographic light-sensitive materials, but matting of photographic light-sensitive materials is also done to prevent static electricity charging, adhesion between photographic light-sensitive materials, and adhesion. The portion is not limited to the surface of the photosensitive layer, and the back surface may also be matted. Even in the matting performed for these purposes, the same problems as those for improving vacuum adhesion described above occurred. Magnetic recording materials may also need to be matted. In recent years, there has been a trend toward significantly smoothing the surface of magnetic recording tapes in order to improve recording density. Therefore, when a magnetic tape is run by a narrow pressure roller in a magnetic recording/reproducing device, there is a problem in that the running performance is deteriorated. Therefore, a mat is provided on the back side of the magnetic tape in order to suppress the deterioration of the running performance of the tape. Furthermore, in the case of magnetic sheets, etc., it is thought that in the future there will be a device that handles many stacked magnetic sheets, and in that case, it is necessary to prevent pecking due to the adhesiveness between stacked magnetic sheets or the generation of static electricity. , it is effective to provide a layer of mat on the back side. The present inventors improved the electrostatic coating technology as a means of matting, and applied this to solve the problems of the conventional method as described above, and also studied to develop a new method. and discovered the present invention. It is an object of the present invention to provide a method in which fine droplets of a resin that has been melted or decomposed are electrostatically flung to form a mat by adhering to the front or back surface of a recording material. The object of the present invention is to provide a method for firmly adhering materials so that they do not fall off during handling. An object of the present invention is to provide a method for electrostatically flying fine droplets of a coating liquid in which a resin is dissolved or dispersed and depositing them on the front or back surface of a recording material to form a mat. Prevents the precipitation of
The objective is to provide a method for stable production over a long period of time. Another object of the present invention is to electrostatically fly and adhere fine droplets, and to apply a coating solution with a boiling point of 130°C.
It is an object of the present invention to provide a recording material matting method that can control the height and shape of matte particles formed from attached droplets by containing the above-mentioned solvent, and can be carried out continuously. The present invention achieves the above-mentioned objects, and its structure is to electrostatically attach fine droplets of a coating liquid in which a resin is dissolved or dispersed to the front and/or back surface of a recording material.・When dried, the coating amount on the front and/or back surface is 0.3 g/m ² or less, the height is 0.5 to 20 μ, the size (diameter) is 1 to 200 μ, and the distribution is 1 to 1000 pieces/mm ² A method of matting by providing mutually independent protrusions made of the resin, wherein the coating liquid is an aqueous liquid containing 5 to 40% by weight of a water-soluble solvent with a boiling point of 130°C or higher. This is a method for matting a recording material, which is characterized by the following. The present invention will be explained in detail below. First, the recording material in the present invention basically has a recording layer provided on a support, and the recording layer may include a photographic photosensitive layer, a magnetic recording layer, or various other recording layers. There are various types depending on the purpose and use. For example, recording materials with a photographic light-sensitive layer include general photographic materials,
There are many examples such as microphotographic materials, radiation-sensitive materials, photographic materials for printing, photographic materials for scientific use, photographic paper, and heat-developable materials. Numerous examples can be cited, such as magnetic recording tape and magnetic recording film. As will be described later, the fundamental technical idea of the present invention is to provide fine mats on the surface of an object, so recording materials are specifically specified as useful objects. Of course, there is no need to ask. In other words, the provision of fine mats can be applied to the surface of any material, but the most effective example of the object to which the present invention can be applied is recording materials, and therefore the present invention is applied to the surface of the material. This invention clarifies the invention by limiting it to recording materials. The support in the recording material of the present invention has a dimensionally stable surface, and in the case of a photosensitive material, it is preferably in the form of a sheet or plate for convenience in handling. In the case of a magnetic recording material, it is in the form of a tape or a sheet, and a preferable form is selected as appropriate depending on the practical use of the recording material or the equipment used. The support material may be paper; for example, paper coated with heat-melting plastic such as polyethylene, polypropylene, or polystyrene, aluminum, various aluminum alloys, metal plates such as zinc, iron, copper, etc.; Cellulose acetate, cellulose butyrate, cellulose acetate butyrate, cellulose propionate, cellulose triacetate, cellulose nitrate,
polyethylene terephthalate, polypropylene,
Plastic films such as polycarbonate, polyvinyl acetal, etc.; paper or plastic films coated with the aforementioned metals by lamination or vapor deposition. The material of the support is also appropriately selected depending on the purpose and use of the recording material. Further, as the recording layer of the recording material, for example, as the photosensitive layer of the photographic light-sensitive material, there are many known ones such as a silver halide-gelatin emulsion photosensitive layer, a diazo resin photosensitive layer, a photosensitive resin photosensitive layer, and others. It is used as a photosensitive layer of the photographic light-sensitive material of the present invention. The same applies to laser recording materials and magnetic recording materials, and known techniques may be used for the other configurations, materials, manufacturing processes, and recording processes and uses of these recording materials, and detailed information is provided here. It seems that no explanation is necessary. The present invention is a method of matting the front and/or back surfaces of the recording material described above, and for this purpose, coating the desired surface with a solvent containing 5 to 40% by weight of a solvent with a boiling point of 130°C or higher in which the resin is dissolved or dispersed. Microscopic droplets of liquid are deposited electrostatically and then dried. Such a coating liquid is preferably one that adheres to the front or back surface of the recording material in a uniformly electrostatically dispersed state. Therefore,
In the case of photographic light-sensitive materials, laser recording materials, etc., the resin for the coating liquid is, for example, JP-A-57-34558.
Copolymers of acrylic esters and acrylic acid or methacrylic acid; copolymers of styrene, acrylic esters, acrylic acid or methacrylic acid; copolymers of acrylic esters, styrene, acrylonitrile, etc. and acrylic Acids or copolymers of methacrylic acid, maleic acid, itaconic acid, etc.; vinyl polymers such as polyvinyl alcohol, polyvinyl acetate, polyvinylpyrrolidone, etc., and these resins are appropriately selected,
A solvent having a boiling point of 130 DEG C. or higher is dissolved or dispersed in a coating solution containing 5 to 40% by weight by a conventionally known method. Solvents with a boiling point of less than 130°C will not provide sufficient effects of the present invention. The solvent having a boiling point of 130°C or higher is preferably a water-soluble solvent, and the amount added is preferably 5 to 40% by weight in the coating solution. If the high boiling point solvent is less than 5% by weight, the effect of the combined use of water will not be sufficiently exerted, while if it is more than 40% by weight, the drying load will be heavy and post-drying will likely be insufficient. Examples of water-soluble solvents with a boiling point of 130℃ or higher include ethylene glycol (boiling point: 197.85℃) ethylene glycol monomethyl ether acetate (boiling point: 145.1℃) ethylene glycol monoethyl ether (boiling point: 134.8℃) ethylene glycol monoethyl ether acetate (Same: 156.4℃) Ethylene glycol monobutyl ether (Same: 171.2℃) Ethylene glycol isoamyl ether (Same: 181℃) Methoxymethoxyethanol (Same: 167.5℃) Ethylene glycol monoacetate (Same: 182℃) Ethylene glycol diacetate (Same: 182℃) Diethylene glycol monomethyl ether (194.2°C) Diethylene glycol monoethyl ether (201.9°C) Diethylene glycol monoethyl ether acetate (217.4°C) Diethylene glycol monobutyl ether (230.4°C) ) Diethylene glycol dimethyl ether (Boiling point: 162℃) Diethylene glycol methyl ether (Boiling point: 145℃) Diethylene glycol diethyl ether (Boiling point: 188.4℃) Diethylene glycol acetate (Boiling point: 250℃) Triethylene glycol (Boiling point: 278.31℃) Triethylene glycol monomethyl ether ( Triethylene glycol monoethyl ether (255.9℃) Tetraethylene glycol (327.3℃) Propylene glycol (188.2℃) Propylene glycol monoethyl ether (132.2℃) 1-Butoxyethoxypropanol (Boiling point: 229.4℃) Dipropylene glycol (Boiling point: 231.8℃) Dipropylene glycol monomethyl ether (Boiling point: 190℃) Dipropylene glycol monoethyl ether (Boiling point: 197.8℃) Tripropylene glycol monomethyl ether (Boiling point: 243℃) Methylene glycol (210-211℃) Butanediol (207.4℃) 1,5-pentanediol (242.5℃) Hexylene glycol (197.1℃) Glycerin (290.0℃) Glycerin acetate (290.0℃) : 158℃) Glycerin diacetate (Boiling point: 259-261℃) etc. As an example of a method for preparing an aqueous liquid, the above-mentioned copolymer can be prepared by emulsifying the raw material monomers in water using a surfactant and using a polymerization initiator such as potassium persulfate, in the same manner as the usual latex synthesis method. It may also be an aqueous dispersion obtained by emulsion polymerization using acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc., or a copolymer aqueous solution may be prepared by adding a portion of acrylic acid, methacrylic acid, maleic acid, itaconic acid, etc. to sodium salt, potassium salt, or ammonium salt. A coating liquid can be prepared by adding a water-soluble solvent having a boiling point of 130° C. or higher to a content of 5 to 40% by weight to these aqueous liquids. These coating solutions may contain fillers such as other water-soluble substances, fine particle powders of inorganic substances, and powders of polymers, which do not affect the photosensitive layer or the attached droplets. In addition, in the case of a mat provided on the back side of a magnetic recording tape, the aqueous resin may be a latex of a copolymer of vinylidene chloride and acrylic ester or acrylic acid, vinyl chloride and vinyl acetate, styrene, etc. copolymer latex,
These include styrene-butadiene copolymer latex, water-soluble polymers of maleic anhydride and acrylic esters, and inorganic powder fillers such as carbon black and colloidal silica, as well as emulsions of fatty acids, fatty acid esters, oils and fats, etc. The boiling point of an aqueous liquid to which substances or salts have been added as a lubricant
A coating solution can be prepared by adding a soluble solvent to water at 130°C or higher. The concentration of the resin in the aqueous liquid is preferably about 5 to 50% by weight. The above-mentioned aqueous liquid is usually made into fine droplets in a process or device that electrostatically deposits the droplets. Such processes or equipment include the conventionally practiced or known electrostatic air spray method, electrostatic airless spray method, rotary atomization electrostatic coating method, and electrostatic coating as described in Japanese Patent Publication No. 55-28740. There are methods such as methods and devices based on each method,
Basically, in both methods, the coating liquid is made into fine particles and electrostatically charged, and the electric field between the electrode and the adhering surface is used to electrostatically coat fine droplets of aqueous liquid. It is attached to the surface. One suitable method for carrying out the present invention is rotary atomization electrostatic coating. This method has been explained in detail in many documents, and many improvements have been made since then. According to this type of device, an aqueous liquid is sprayed onto the inner peripheral surface of the rear part of a cup-shaped spray head that rotates at a speed of 10,000 to 50,000 per minute.
The aqueous liquid in the spray head is continuously supplied at a rate of ~1000 c.c./min, and the aqueous liquid in the spray head is formed into a thin film on the inner peripheral surface by the centrifugal force caused by rotation, and this thin film is flowed onto the cup-shaped surface along with the supply. A voltage of -50 to -120 KV is applied to the tip of the spray head along with its centrifugal force, and the electrostatic action of the tip causes the spray to be emitted and atomize, resulting in a high voltage formed between the rotating cup spray head and the surface of the recording material. The action of the electric field causes atomized and charged fine droplets to fly and adhere to the surface of the recording material. The most distinctive feature of the present invention is that, as described above, the coating solution contains a solvent with a boiling point of 130° C. or higher, and the droplets are electrostatically attached. boiling point
If no solvent is used at a temperature of 130°C or higher, the charged and atomized fine droplets will dry while flying to the surface of the recording material, resulting in droplets with a higher concentration than the initial concentration, resulting in extremely fine droplets. In some cases, it becomes a fine powder of dried resin. Therefore, when a droplet adheres to the surface of a recording material, it is difficult for the droplet to wet and spread, and because the contact area becomes small, it easily falls off, and when it becomes a dry fine powder, it is because the spherical fine powder is electrostatically attached. It gets too old. To prevent this phenomenon, a solvent with a boiling point of 130°C or higher is added.
By adding a high-boiling point solvent, the solvent does not dry completely even when it is blown onto the recording material, making it easier to wet and spread on the surface of the recording material, thereby forming a firmly fixed mat. This high boiling point solvent can be reduced to a level that does not affect product performance through a drying process after mat formation. Another effect of the present invention is that in the above-mentioned rotary atomization electrostatic coating method, the flow of the thin film coating liquid within the rotating cup-shaped spray head tends to be partially impaired, and when the coating liquid is continuously operated for a long period of time, the resin However, by adding a high boiling point solvent, drying and precipitation can be suppressed and stable production can be carried out for a long time. In the process of the present invention, the concentration of the resin and high boiling point solvent in the coating solution, the size of the atomized droplets, the surface temperature of the recording material, the running speed of the recording material, and the time after the droplets are attached to the surface are determined. The time taken to dry affects the form of the pine that is formed. By changing these various conditions, the height of the pine after being dried can be arbitrarily controlled. As described above, the recording material to which fine droplets of a coating liquid containing a solvent with a boiling point of 130°C or higher are attached is dried, and the solid portion of the droplets is firmly adhered to the surface to form a mat. . The added high-boiling solvent is then reduced to a level that does not adversely affect the performance of the product. For drying and its conditions, techniques conventionally known in the art may be used, such as blowing warm air onto the recording material, passing it through a high temperature and low humidity room, or drying with an infrared heater. The dried mats are scattered as independent protrusions on the surface of the recording material, and in the case of photographic materials, the coating amount is
0.3g/ ^m2 or less, preferably 0.15g/ ^m2 or less, distribution amount 1 to 1000 pieces/ ^mm2 , preferably 5 to 500 pieces/mm2.
The diameter of ^each pine particle is preferably in the range of about 0.5 to 20 μm in height and 1 to 200 μm in size (diameter). If the coating amount is 0.3 g/m ² or more, it becomes difficult to remove the high boiling point solvent by post-drying. In addition, for materials other than photographic materials, the distribution amount is 10 to 500.
pieces/mm ² , the height of the pine particles is about 0.03 to 1.5 μ, and the diameter of the pine particles is about 10 to 1000 μ. Hereinafter, the present invention will be specifically explained based on Examples. Example 1 Both sides of an aluminum plate with a thickness of 0.24 mm were grained using a nylon brush and 400 mesh of pumice stone-water suspension, and thoroughly washed with water. This board was placed in an aqueous solution of tribasic sodium phosphate (5%) at 70°C for 3 minutes.
After soaking for a minute, it was washed with water and dried. This support is mixed with part by weight of naphthoquinone-1,2-cyazido-5-sulfonic acid ester of polyhydroxyphenyl obtained by polycondensation of acetone and pyrogallol as described in Japanese Patent Publication No. 43-28403, and novolac type phenol. 2 parts by weight of formaldehyde resin and 20 parts by weight of 2-methoxyethyl acetate
A photosensitive solution was prepared by dissolving it in 20 parts by weight of methyl ethyl ketone, and it was sequentially applied to one side of the support and dried, and matt was applied by spraying as described below to prepare a double-sided photosensitive lithographic printing plate. The printing plate thus prepared was cut into four pieces measuring 1003 mm x 800 mm and designated as samples A, B, C, and D, respectively. The composition of the coating liquid for each of these samples is shown in Table 1.

【table】

[Table] These coating solutions were coated using an electrostatic coating device having a cup-shaped rotating atomizing head under the following conditions. Amount of water-based paint sent: 50 milliliters per minute Voltage applied to the electrostatic coating head: -90 kilovolts Atomization head rotation speed: 30,000 revolutions per minute The fine droplets of the applied coating solution were dried. The time from application to the drying room was approximately 3 seconds for both samples, and samples A and B were dried in an atmosphere of 60°C and 10% humidity.
Samples C and D were dried with dry hot air at 120°C for 15 seconds. At the start of production for each sample, the coating amount of mats formed after drying was 0.06 g/m ² for each sample, with a distribution of 50 to 100 pieces/mm ² .
The height was about 2-6μ, and the diameter was about 10-50μ. The dirt on the transport roll when the sample prepared as above was brought into contact with the transport roll, and the vacuum adhesion time (unit: (Second), the dirt on the original film plate after vacuum adhesion and the state of resin precipitation on the bell were investigated. The stains were classified into four ranks: ○, Δ, ×, and XX, with ○ indicating no stains and XX indicating extremely dirty stains. The results are shown in Table 2.

[Table] In A using a conventional coating liquid, the conveying roller and film base plate were dirty, and the mat was easy to come off, resulting in poor vacuum adhesion on the back side. In addition, precipitation in the coating bell was severe, and defective mats were produced within one hour, making it necessary to stop production and clean the bell. On the other hand, when a solvent is added, isopropyl alcohol has no effect at all, and ethylene glycol monomethyl ether (boiling point 124.4°C) has an effect, but it is found to be insufficient. Sample D according to the present invention could be operated continuously for a long time without causing resin precipitation on the bell or staining of the conveying roller or film original plate. Furthermore, it was confirmed that the vacuum adhesion time was also stable. Example 2 The double-sided type photosensitive lithographic printing plate in Sample D of Example 1 was changed to a single-sided type, and a similar test was conducted. The surface exhibited vacuum adhesion similar to that of Sample D of Example 1, and neither the conveying roll nor the film original plate was observed to be stained. Example 3 One side of the double-sided photosensitive lithographic printing plate in Sample D of Example 1 was coated at 4000 revolutions per minute using a disk instead of the cup-shaped rotating atomizing head in Sample D of Example 1. As a result, Example 1
Good results similar to those of sample D were obtained. Example 4 Styrene-butadiene copolymer latex “NIPOL-LX-204” (Nippon Zeon Co., Ltd.), colloidal silica “Snowtex OL” (Nissan Chemical Co., Ltd.)
), 2, 1 and 2 parts by weight of sodium stearate (first class reagent) as solid content, 8 parts by weight of methoxymethoxyethanol (boiling point 167.5°C),
An aqueous dispersion of a synthetic resin was prepared in which the remaining 87 parts by weight was water, and it was applied to the back side of a VHS type magnetic tape for long-term recording to form a mat in the same manner as in the above example. The shape of the pine is 10 to 60μ in diameter.
Height 0.03~0.3μ, distribution amount of pine 10~80 pieces/ ^mm2
It was hot. When this sample and a similar type of magnetic tape without a mat were run on a video tape recorder to examine the tape's ejection and running conditions, the sample of this example showed good results, but the tape of the comparative sample was slightly inferior. The results were as follows. Also, the adhesion of the mats was good and did not come off at all during several driving tests. The present invention described in detail above is applicable to forming a mat by electrostatically depositing fine droplets of aqueous liquid on the front or back surfaces of various recording materials and drying them. In other words, it improves the vacuum adhesion of various recording materials, prevents mutual adhesion or adhesion, prevents static electricity, provides writability, improves the running properties of tape-shaped recording materials in cassettes, and prevents magnetic films from sticking. Various objectives can be achieved, such as prevention. According to the present invention, it is possible to uniformly distribute and provide fine mats on the recording material, and the mats attached to the recording material are extremely firmly attached and do not fall off easily. . Therefore, even in the case of photographic light-sensitive materials, the reproducibility of halftone dots is good without impairing the original photographic properties. In addition, it is a method that allows the height of the pine to be adjusted appropriately according to the various intended uses as mentioned above, and it also allows stable production with simpler equipment than conventional methods. be.

Claims (1)

[Claims] 1. Fine droplets of a coating liquid in which a resin is dissolved or dispersed are electrostatically adhered to the front and/or back surface of a recording material and dried to form a coating amount on the front and/or back surface. 0.3g/ ^m2 or less, height 0.5~20μ, size (diameter) 1~200μ, distribution amount 1~1000 pieces/ ^mm2
A method of matting by providing mutually independent protrusions made of the resin, wherein the coating liquid is an aqueous liquid containing 5 to 40% by weight of a water-soluble solvent with a boiling point of 130°C or higher. A method for matting a recording material, characterized in that: 2. The matting method according to claim 1, wherein the recording material is a photosensitive lithographic printing plate.