JP5058216B2 - Manufacturing method of plate-like molded product - Google Patents

Description

  The present invention relates to a method for producing a plate-like molded product.

  Conventionally, as a method for producing a plate-like molded product, a vinyl monomer is injected into a pair of molds made of an inorganic glass or metal plate whose four sides are sealed with a gasket such as polyvinyl chloride, and polymerized in the mold to form a plate. A cell casting method for obtaining a molded product, and a mold consisting of one endless belt of mirror-polished stainless steel plate or two endless belts of stainless steel plates arranged so as to face the upper and lower sides and between the belts on both sides Continuously supplying a vinyl monomer solution or a vinyl monomer solution in which a thermoplastic resin is dissolved (hereinafter referred to as “syrup”) to a mold formed by sealing with a gasket sandwiched between There is a continuous plate making method in which a plate-like molded product is obtained by polymerization.

  In the above manufacturing method, when the obtained plate-shaped molded product is peeled from the mold, there is a problem that the plate-shaped molded product is firmly adhered to the mold and cannot be easily peeled off.

  As a method for solving this problem, Patent Document 1 proposes a method of etching a surface of a stainless steel plate used as a mold that comes into contact with a vinyl monomer with nitric acid or the like.

  However, when manufacturing a plate-like molded article having a cured film having excellent scratch resistance and the like as disclosed in Patent Document 2, the adhesiveness between the cured film and the mold is the above vinyl weight. Since it is higher than the adhesion between the coalescence and the mold, the method disclosed in Patent Document 1 cannot be said to have sufficient peelability between the cured film and the mold. Further, as disclosed in Patent Document 2, there is a method of adding a release agent to the monomer raw material for forming a cured film, but the release agent remains on the surface of the stainless steel plate after polymerization, There is a problem of contaminating the surface.

JP 2007-230220 A Japanese Patent Publication No. 47-13147

  The object of the present invention is to select a specific part that has good releasability between a mold made of a stainless steel plate and a cured film of a monomer having at least two (meth) acryloyloxy groups in the molecule, and is safe. It is an object of the present invention to provide a method for producing a plate-shaped molded article that can be subjected to a general treatment and uses less nitric acid solution.

  The gist of the present invention is that a base material containing a nitric acid solution having a concentration of 1 to 50% by mass is brought into contact with a stainless steel plate and treated with the nitric acid solution, the surface of the mold made of the stainless steel plate after the treatment. And a step of curing the coating layer after forming a coating layer containing a monomer having at least two (meth) acryloyloxy groups in the molecule, and forming a cured coating on the surface of the cured coating. A plate shape having a step of forming a vinyl polymer layer by polymerizing the vinyl monomer layer after forming the vinyl monomer layer, and a step of peeling the vinyl polymer layer laminated with the cured film from the surface of the mold It is a manufacturing method of a molding.

  According to the present invention, it is possible to avoid the trouble of peeling failure between the cured film and the mold when producing a plate-like molded article in which a cured film having excellent scratch resistance and the like is laminated on the surface using the mold. Productivity is good, and production with a reduced mold surface cleaning process is possible.

  Moreover, by using a base material containing a nitric acid solution in contact with the stainless steel plate, the amount of nitric acid solution used can be suppressed, and a safe treatment is possible. Furthermore, in this treatment method, it is possible to selectively treat a specific part, and the amount of nitric acid solution used can be further reduced and the treatment can be performed safely.

Stainless steel sheet The material of the stainless steel sheet used in the present invention includes, for example, austenite (SUS304, SUS316, etc.), ferrite (SUS430, etc.) and martensite (SUS403, etc.). Among these, an austenitic system is preferable in terms of corrosion resistance. Moreover, as a surface state of a stainless steel plate, it is preferable that it is mirror-polished so that the surface of the hardened film obtained may become smooth.

  In the present invention, the surface of the stainless steel plate is treated with a nitric acid solution having a concentration of 1 to 50% by weight at least on the surface that comes into contact with a monomer having at least two (meth) acryloyloxy groups in the molecule described later. ing.

In addition, the nitric acid aqueous solution of pH 1-4 used in Patent Document 1 described above has a concentration of 6.3 × 10 ⁻⁴ mass% (pH 4) to 0.63 mass% (pH 1). On the other hand, in the present invention, since a nitric acid solution having a concentration of 1% by mass or more is used, in particular, a cured film of a treated stainless steel plate and a monomer having at least two (meth) acryloyloxy groups in the molecule. Peelability with respect to (hereinafter referred to as “main cured film”) becomes good. This concentration is preferably 10% by mass or more. Further, if the concentration of the nitric acid solution is 50% by mass or less, the odor when the nitric acid solution is heated is suppressed, which is preferable in terms of workability. Further, as described later, a cloth impregnated with the nitric acid solution is used. When processing the surface of a stainless steel plate using a base material, discoloration of the base material such as cloth is suppressed, which is preferable in terms of safety. The solvent used for the nitric acid solution is not particularly limited, but water is preferable from the viewpoint of handleability and safety.

  In the present invention, additives and the like can be added to the nitric acid solution as necessary.

  Although the temperature which processes a stainless steel plate with a nitric acid solution is not specifically limited, 20 degreeC or more is preferable at the point of a processing effect, and 40 degreeC or more is more preferable. Further, the upper limit temperature is preferably 90 ° C. or less from the viewpoint of safety. In order to set the treatment temperature to a desired value, for example, a method of warming a nitric acid solution or heating a stainless steel plate can be performed.

  In the present invention, a base material containing a nitric acid solution is treated by contacting with a stainless steel plate. This method is preferable from the viewpoint of safety, the case where only the surface of a specific portion is treated, and the reduction of the nitric acid solution, as compared with other treatment methods using a nitric acid solution. Here, when treating only the surface of a specific location, for example, even if it is a stainless steel plate that has been treated with a nitric acid solution, it needs to be partially reprocessed due to repair of scratches on the surface, etc. And according to the present invention, only the specific portion can be safely treated with a small amount of nitric acid solution.

  The base material contains and holds a nitric acid solution, and when the nitric acid solution oozes out onto the stainless steel plate when it is brought into contact with the stainless steel plate, the surface of the desired location of the stainless steel plate may be in contact with the nitric acid solution. . The base material is preferably made of a material that does not undergo modification such as decomposition by nitric acid. For example, acid-resistant cloth or gel can be used as the base material. As the acid-resistant cloth, a cellulose nonwoven fabric is particularly preferable. In addition, cloths made of olefin fibers such as polyethylene fibers and polypropylene fibers can also be used.

  A method for incorporating the nitric acid solution into the base material is not particularly limited. For example, a method of immersing a base material in a nitric acid solution, a method of dropping a nitric acid solution into the base material, and the like can be mentioned.

  When the base material containing the nitric acid solution is in contact with the stainless steel plate, the evaporation of the nitric acid solution can be suppressed by covering the evaporation preventing material, and the treatment can be performed more safely and efficiently. For example, it is preferable to use a film or sheet for preventing evaporation. In particular, a film or sheet made of polyethylene terephthalate (hereinafter referred to as “PET”) is preferable. In addition, a film or sheet made of polyolefin such as polyethylene or polypropylene can be used.

  As time to process the surface of a stainless steel plate with a nitric acid solution, 5 minutes or more are preferable and 30 minutes or more are more preferable. The upper limit time is not particularly limited, but a treatment of 24 hours or less is sufficient.

  If the nitric acid solution remains on the surface of the stainless steel plate treated with the nitric acid solution, the surface of the stainless steel plate may be deteriorated or the surface of the resulting plate-shaped molded product may become rough. It is preferable to do.

  The cleaning solution for the nitric acid solution is not particularly limited as long as it dissolves nitric acid, but water is preferable in terms of handleability. After washing, the stainless steel plate treated with the nitric acid solution can be obtained by drying the water adhering to the surface of the stainless steel plate.

As the monomer having at least two (meth) acryloyloxy groups in the molecule having at least two (meth) acryloyloxy groups in the molecule, for example, 1 mol of polyhydric alcohol and 2 mol Esterified products obtained from the above (meth) acrylic acid or derivatives thereof, polyhydric alcohols, polycarboxylic acids or anhydrides thereof, esterified products obtained from (meth) acrylic acid or derivatives thereof, and other polyfunctionalities Monomer.

  In the present invention, “(meth) acryloyl”, “(meth) acryl” and “(meth) acrylate” mean acryloyl or methacryloyl, acrylic or methacryl, and acrylate or methacrylate, respectively.

  Examples of the esterified product obtained from 1 mol of polyhydric alcohol and 2 mol or more of (meth) acrylic acid or a derivative thereof include diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, and tetraethylene. Poly (ethylene glycol) di (meth) acrylate such as glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) ) Acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, pentaglycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) a Relate, glycerin tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra ( Examples include (meth) acrylate, tripentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, and tripentaerythritol hepta (meth) acrylate.

  Examples of the esterified product obtained from the above polyhydric alcohol, polycarboxylic acid or anhydride and (meth) acrylic acid or derivative thereof include, for example, polyhydric alcohol / polycarboxylic acid or anhydride / The thing obtained from the combination of (meth) acrylic acid is mentioned. Examples of combinations of polyhydric alcohol / polycarboxylic acid or anhydride / (meth) acrylic acid include malonic acid / trimethylol ethane / (meth) acrylic acid, malonic acid / trimethylolpropane / (meth) acrylic acid. , Malonic acid / glycerin / (meth) acrylic acid, malonic acid / pentaerythritol / (meth) acrylic acid, succinic acid / trimethylolethane / (meth) acrylic acid, succinic acid / trimethylolpropane / (meth) acrylic acid, Succinic acid / glycerin / (meth) acrylic acid, succinic acid / pentaerythritol / (meth) acrylic acid, adipic acid / trimethylolethane / (meth) acrylic acid, adipic acid / trimethylolpropane / (meth) acrylic acid, adipine Acid / glycerin / (meth) acrylic acid, adipic acid / penta Lithritol / (meth) acrylic acid, glutaric acid / trimethylolethane / (meth) acrylic acid, glutaric acid / trimethylolpropane / (meth) acrylic acid, glutaric acid / glycerin / (meth) acrylic acid, glutaric acid / pentaerythritol / (Meth) acrylic acid, sebacic acid / trimethylolethane / (meth) acrylic acid, sebacic acid / trimethylolpropane / (meth) acrylic acid, sebacic acid / glycerin / (meth) acrylic acid, sebacic acid / pentaerythritol / (Meth) acrylic acid, fumaric acid / trimethylolethane / (meth) acrylic acid, fumaric acid / trimethylolpropane / (meth) acrylic acid, fumaric acid / glycerin / (meth) acrylic acid, fumaric acid / pentaerythritol / ( (Meth) acrylic acid, itaconic acid / g Methylolethane / (meth) acrylic acid, itaconic acid / trimethylolpropane / (meth) acrylic acid, itaconic acid / glycerin / (meth) acrylic acid, itaconic acid / pentaerythritol / (meth) acrylic acid, maleic anhydride / tri Combinations of methylolethane / (meth) acrylic acid, maleic anhydride / trimethylolpropane / (meth) acrylic acid, maleic anhydride / glycerin / (meth) acrylic acid and maleic anhydride / pentaerythritol / (meth) acrylic acid Can be mentioned.

  Examples of the other polyfunctional monomers include trimethylolpropane toluylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), isophorone diisocyanate, To 1 mol of polyisocyanate obtained by trimerization of diisocyanate such as trimethylhexamethylene diisocyanate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxy-3-methoxypropyl (meth) acrylate, N-methylol (meth) acrylamide, N-hydroxy (meth) acrylamide, 1,2,3-propanetriol-1,3 Urethane poly (meth) acrylate obtained by reacting 3 mol or more of an acrylic monomer having active hydrogen such as di (meth) acrylate and 3-acryloyloxy-2-hydroxypropyl (meth) acrylate; Examples include poly [(meth) acryloyloxyethylene] isocyanurates and epoxy poly (meth) acrylates such as di (meth) acrylate or tri (meth) acrylate of hydroxyethyl) isocyanuric acid.

  The monomers having at least two (meth) acryloyloxy groups in these molecules can be used alone or in combination of two or more.

Coating layer containing monomer having at least two (meth) acryloyloxy groups in the molecule In the present invention, it contains a monomer having at least two (meth) acryloyloxy groups in the molecule. The method for curing the coating layer (hereinafter referred to as “this coating layer”) is not particularly limited, but it is preferable to cure with an active energy ray in terms of curing time and curing temperature.

  When this coating film layer is cured with active energy rays, it is preferable that a photoinitiator is contained in the coating film layer.

  Examples of the photoinitiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, acetoin, butyroin, toluoin, benzyl, benzophenone, p-methoxybenzophenone, 2,2-diethoxyacetophenone, α , Α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4′-bis (dimethylamino) benzophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one Carbonyl compounds such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide and the like; 2,4,6-trimethylbenzoyldiphenylphosphine oxide and Emissions benzoyl diethoxy phosphine oxide. These can be used alone or in combination of two or more.

  The addition amount of the photoinitiator is preferably 0.1% by mass or more in the present coating layer in terms of curability of the present coating layer, and is 10% by mass or less in terms of improving the color tone of the resulting cured coating. preferable.

  In the present invention, if necessary, a monomer having one vinyl group in the molecule in the coating layer, a leveling agent, conductive inorganic fine particles, inorganic fine particles not having conductivity, an ultraviolet absorber, Various components such as a light stabilizer can be contained. Their added amount is preferably 10% by mass or less in the coating layer.

  Examples of monomers having one vinyl group in the molecule include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, and i-butyl (meth) acrylate. , T-butyl (meth) acrylate, amyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) ) (Meth) acrylates such as acrylates; vinyl aromatics such as styrene, α-methylstyrene, paramethylstyrene, isopropenylstyrene, vinyltoluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; methacrylic , Acrylic acid, unsaturated carboxylic acids such as maleic acid; and ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, crosslinking monomer, such as divinylbenzene. These can be used alone or in combination of two or more.

  Examples of the method for forming the coating layer on the mold surface include a method in which the raw material for the coating layer is applied to the mold surface and pressure-bonded with a rubber roll. In addition, in order to prevent air entrainment when applying the raw material of the coating layer to the mold surface, apply an excessive amount of the raw material of the coating layer to the surface of the mold and rub it with a rubber roll through the film. The method of applying is preferable. An example of the film used at this time is a PET film.

Main cured film In the present invention, the main coating layer formed on the surface of the mold made of stainless steel plate is cured to obtain the main cured film.

  Although the thickness of this hardened film is not specifically limited, 5-100 micrometers is preferable. When the thickness of the cured film is 5 μm or more, sufficient surface hardness of the cured film tends to be exhibited, and when the thickness is 100 μm or less, coloring of the cured film tends to be suppressed.

  In the present invention, examples of the active energy ray source used when the present coating layer is cured with an active energy ray to form a fully cured coating include an ultraviolet lamp.

  Examples of the ultraviolet lamp include a high-pressure mercury lamp, a metal halide lamp, and a fluorescent ultraviolet lamp.

  In the present invention, when the coating layer is formed by squeezing with a rubber roll through a film, the film may be peeled off and then irradiated with ultraviolet light, or the film may be irradiated with ultraviolet light. May be. Further, depending on the purpose, it is possible to carry out curing divided into a plurality of stages, such as irradiating ultraviolet rays through a film and pre-curing, then peeling the film, and then further irradiating with ultraviolet rays and post-curing.

Vinyl monomer layer In the present invention, after a main cured film is formed on the mold surface, a vinyl monomer layer is formed on the surface of the main cured film, and then the vinyl monomer layer is polymerized to form a vinyl polymer layer. To form.

  Examples of the vinyl monomer that is a raw material for the vinyl monomer layer include a monomer mixture containing methyl methacrylate or methyl methacrylate and another vinyl monomer that can be copolymerized.

  Examples of other copolymerizable vinyl monomers include methyl acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl ( (Meth) acrylate, amyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, etc. (Meth) acrylates; vinyl aromatics such as styrene, α-methylstyrene, paramethylstyrene, isopropenylstyrene, vinyltoluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; methacrylic acid, acrylic acid, Unsaturated carboxylic acids such as aqueous maleic acid; and ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, crosslinking monomer, such as divinylbenzene. These can be used alone or in combination of two or more.

  In the present invention, as a raw material for the vinyl monomer layer, it is possible to use a syrup such as the above monomer solution in which a thermoplastic resin such as a partial polymer solution of the above monomer or polymethyl methacrylate is dissolved. it can.

  The vinyl monomer layer can contain a polymerization initiator and, if necessary, a molecular weight modifier.

  Examples of the polymerization initiator include azo polymerization initiators such as azobisisobutyronitrile and azobisdimethylvaleronitrile, benzoyl peroxide, t-butylperoxy 2-ethylhexanoate, and t-hexylperoxypioxy. Examples thereof include organic peroxides such as barate.

  Examples of the molecular weight modifier include alkyl mercaptans such as n-butyl mercaptan, n-dodecyl mercaptan, and octyl mercaptan.

  In the present invention, if necessary, in order to facilitate the peeling of the cured film from the stabilizer, flame retardant, plasticizer, mold, etc. in the vinyl monomer layer, such as dyes, pigments, antioxidants, and UV absorbers. Additives such as a release agent, a chain transfer agent, and a crosslinking agent can be contained.

  As a method of forming the vinyl monomer layer on the surface of the main cured film, for example, the side of the surface side of the main cured film of the mold on which the main cured film is laminated is sealed with a gasket, and then the vinyl monomer layer is formed. A method of casting a raw material can be mentioned. In this case, the monomer layer may be sealed by covering the surface of the vinyl monomer layer with a film.

  In addition, as another method for forming a vinyl monomer layer on the surface of the main cured film, glass, steel plate, etc. whose sides are sealed with a gasket or the like on the surface side of the main cured film of the mold on which the main cured film is laminated There is also a method in which another mold made of is placed so that the surfaces sealed with a gasket or the like are overlapped, and the raw material of the vinyl monomer layer is injected into the formed space.

Vinyl polymer layer The vinyl polymer layer is formed by polymerizing a vinyl monomer layer.

  The polymerization temperature varies depending on the type of polymerization initiator used, but is preferably 40 to 140 ° C. in terms of ease of control of the polymerization reaction and productivity. More preferably, the polymerization is carried out in two stages, the first stage polymerization is 40 to 90 ° C., and the second stage polymerization is 100 to 140 ° C.

After the vinyl monomer layer is polymerized to form a vinyl polymer layer, the vinyl polymer layer on which the main cured film is laminated is peeled from the surface of the mold to obtain a plate-like molded product.

  Hereinafter, the present invention will be described by way of examples.

[Example 1]
A stainless steel sheet (material: SUS304, size: length 160 mm, width 160 mm, thickness 1 mm) that has been mirror-polished is held so that the surface temperature is 45 ° C., and a cellulose nonwoven fabric impregnated with 30% by mass nitric acid aqueous solution. (Vertical 180 mm, horizontal 180 mm, thickness of about 8 mm, no discoloration) was placed on a stainless steel plate, and a PET film was further placed thereon and allowed to stand for 1 hour.

  Thereafter, the PET film and the cellulose nonwoven fabric were removed, and the stainless steel plate was sufficiently washed with distilled water. After washing with water, the surface of the stainless steel plate was dried by blowing dry air.

  On the stainless steel sheet treated with the nitric acid solution obtained above, a succinic acid / trimethylolethane / acrylic acid (molar ratio: 1/2/4) condensation mixture (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name) : TAS) 50 parts by mass, 1,6-hexanediol diacrylate (Osaka Organic Chemical Industry Co., Ltd., trade name: C6DA) 50 parts by mass and benzoin ethyl ether (Seiko Chemical Co., Ltd., trade name: BEE) About 0.2 ml of a raw material for a coating layer composed of 1.5 parts by mass is dropped, and about 80 mm square with a rubber roller over a 100 μm-thick PET film (trade name: Teijin Tetron Film G2 manufactured by Teijin DuPont Films Ltd.) The coating was applied while squeezing to form a coating layer having a thickness of about 20 μm.

Next, after the PET film is peeled off, the surface of the coating layer is irradiated with ultraviolet rays so that the irradiation energy is 1,000 mJ / cm ² using an ultraviolet lamp (Igrantage ECS-401GX manufactured by IGraphic), and cured. A coating was obtained.

  A PET film similar to the above was coated on one side of a tempered glass having the same size as a separately prepared stainless steel plate. The tempered glass coated with this PET film is arranged so that the surface coated with the PET film faces the surface on which the hardened coating of the stainless steel plate is laminated, and the end portions of the four sides of the tempered glass and the stainless steel plate between them. A gasket made of polyvinyl chloride having a thickness of 2.8 mm was placed, and a stainless steel plate and tempered glass were fixed with clips to produce a mold.

  In this mold, 100 parts by mass of a solution obtained by dissolving 20 parts by mass of polymethyl methacrylate having a mass average molecular weight of 220,000 in 80 parts by mass of methyl methacrylate, t-hexyl peroxypivalate (manufactured by NOF Corporation, trade name: Perhexyl PV) 0.05 parts by mass, dioctylsulfosuccinate sodium salt (Nippon Cytec Industries, Ltd., trade name: AEROSOL OT-100) 0.003 parts by mass and ethyl acid phosphate (Johoku Chemical Industry Co., Ltd.) Manufactured, trade name: JP502) The raw material of the vinyl monomer layer consisting of 0.003 part by mass was injected, and polymerized in an 80 ° C. water bath for 30 minutes and then in an air furnace at 130 ° C. for 30 minutes. Thereafter, the mold is taken out from the air furnace, and after the temperature of the stainless steel plate reaches 110 ° C., the tempered glass and the PET film are removed, the vinyl polymer layer on which the cured coating is laminated is peeled off from the stainless steel plate, Obtained. At this time, the cured film could be easily peeled from the stainless steel plate.

[Example 2]
A plate-like molded body was obtained in the same manner as in Example 1 except that the concentration of the aqueous nitric acid solution was 10% by mass. At this time, the cured film required a little force, but could be peeled off from the stainless steel plate.

[Example 3]
The concentration of the aqueous nitric acid solution for treating the stainless steel plate was 20% by mass. Otherwise, a plate-like molded body was obtained in the same manner as in Example 1. At this time, the cured film required a little force, but could be peeled off from the stainless steel plate.

[Example 4]
First, an endless belt made of a stainless steel plate (material: SUS304, width: 1500 mm, thickness: 1 mm) subjected to mirror polishing (φ100 mm) was prepared. A specific part of the surface of the endless belt is heated with a hot plate from the bottom, the surface temperature of the part is maintained at 45 ° C., and a cellulose nonwoven fabric impregnated with 30% by mass nitric acid aqueous solution (length 130 mm, width 130 mm, thickness (Approx. 8 mm) was placed on the portion, and a PET film was further placed thereon, and allowed to stand for 1 hour.

  Thereafter, the PET film and the cellulose nonwoven fabric were removed, the portion was sufficiently washed with a cloth soaked with distilled water, and then the moisture was removed by wiping and dried.

  The raw material of the coating layer similar to Example 1 was dripped at the specific part of the endless belt which consists of a stainless steel plate processed with the nitric acid solution obtained as mentioned above. And it apply | coated, squeezing about 150 mm square through 50-micrometer-thick PET film, and the coating-film layer of thickness about 20 micrometers was formed.

  Next, the PET film was taken out and irradiated with ultraviolet rays in the same manner as in Example 1 to obtain a cured coating.

  Then, a gasket made of polyvinyl chloride was disposed between two endless belts in total, that is, the endless belt on which the cured film was formed and another endless belt of the same size, thereby completing the mold.

  In this mold, 100 parts by mass of a solution obtained by dissolving 20 parts by mass of polymethyl methacrylate having a mass average molecular weight of 220,000 in 80 parts by mass of methyl methacrylate, t-hexyl peroxypivalate (manufactured by NOF Corporation, trade name: 0.19 parts by mass of perhexyl PV), sodium salt of dioctylsulfosuccinate (manufactured by Nippon Cytec Industries, Ltd., trade name: AEROSOL OT-100) and ethyl acid phosphate (Johoku Chemical Industry Co., Ltd.) (Product name: JP502) A vinyl monomer layer raw material consisting of 0.006 parts by mass was injected and polymerized in a hot water shower at 82 ° C and then in an air furnace at 130 ° C.

  After completion of the polymerization, the vinyl polymer layer on which the cured film was laminated was peeled off from the endless belt, and a plate-like molded body was continuously obtained. At this time, the cured film could be easily peeled from the endless belt.

[Comparative Example 1]
An attempt was made to produce a plate-like molded body in the same manner as in Example 1 except that the concentration of the aqueous nitric acid solution was 0.1% by mass. However, the vinyl polymer layer on which the cured film was laminated could not be peeled from the stainless steel plate.

[Comparative Example 2]
An attempt was made to produce a plate-like molded body in the same manner as in Example 1 except that the nitric acid treatment was not performed. However, the vinyl polymer layer on which the cured film was laminated could not be peeled from the stainless steel plate.

[Comparative Example 3]
A plate-like molded body was manufactured in the same manner as in Example 1 except that the concentration of the nitric acid aqueous solution was 60% by mass. However, discoloration (yellowing) was observed in the cellulose nonwoven fabric soaked with an aqueous nitric acid solution, and the nitric acid odor was trapped when heated in the nitric acid treatment step, so production was stopped.

Claims (1)

A step of contacting a base material containing a nitric acid solution having a concentration of 1 to 50% by mass with a stainless steel plate and treating with the nitric acid solution;
After forming a coating layer containing a monomer having at least two (meth) acryloyloxy groups in the molecule on the surface of the mold made of the stainless steel plate after the treatment, the coating layer is cured and cured. Forming a film;
Forming a vinyl monomer layer on the surface of the cured film, then polymerizing the vinyl monomer layer to form a vinyl polymer layer, and peeling the vinyl polymer layer on which the cured film is laminated from the mold surface The manufacturing method of the plate-shaped molding which has a process.