JP5773672B2 - Resin-coated metal plate for surface processing, method for producing the same, and method for producing metal decorative plate - Google Patents

Description

  The present invention relates to a resin-coated metal plate for surface processing suitable for surface processing such as mechanical polishing and blasting, a manufacturing method thereof, and a method of manufacturing a metal decorative plate using the resin-coated metal plate for surface processing.

  The surface of a metal plate such as a stainless steel plate that has been finished to a mirror or semi-mirror surface may be subjected to surface treatment to draw a pattern. The surface treatment is usually performed by masking a part of the surface of the metal plate; performing mechanical polishing such as hairline polishing or vibration polishing or shot blasting processing such as bead shot or sand shot on an unmasked portion; Next, a step of removing the masking is included. With this surface treatment, a metal with a pattern that is a combination of a mirror or semi-finished surface and a hairline or vibration-finished surface, or a combination of a mirror or semi-mirror-finished surface and a shot blasted surface A decorative board can be manufactured.

  It is known that a masking layer for mechanical polishing is formed by screen printing or pad printing of an oxidation polymerization type ink, a synthetic resin ink or a natural resin ink (see Patent Documents 1 and 2). Furthermore, it has also been proposed that the masking layer is formed by sticking a pre-cut adhesive sheet made of vinyl chloride or soft resin (see Patent Documents 3 to 5).

  It has been proposed that a masking layer for shot blasting is formed by screen printing with an ink based on a rubber resin having high impact resistance (see Patent Document 6). In addition, a predetermined pattern portion is formed on the surface of the metal plate using a photosensitive resist; a silicon rubber-based resin is applied to the exposed surface of the metal plate; There has also been proposed a method of simultaneously performing exposure of a portion and surface processing of the exposed portion (see Patent Document 7).

  The metal plate for resin coating is usually washed and dried after degreasing treatment such as alkali degreasing, solvent degreasing, or electrolytic degreasing. In addition, the metal plate may be further pickled after being degreased and then washed and dried. However, a thick oxide film is often formed on the surface of the metal plate. For this reason, even when sufficient degreasing treatment is performed, the adhesion between the resin film and the metal plate is often insufficient. If the adhesion between the resin film and the metal plate is insufficient, the resin film functioning as a masking layer is peeled off during mechanical polishing or shot blasting. Therefore, it is required that the resin film serving as a masking layer for mechanical polishing or shot blasting has sufficient adhesion to the metal plate.

  In order to improve adhesion to a metal plate, an ink to which a phosphate ester-based polymerizable compound is added has been proposed (see Patent Documents 8 and 9). In addition, a coating material in which a phosphate ester-based polymerizable compound, a polyurethane resin, an amine compound, and an α-hydroxyketone-based initiator are added has been proposed (see Patent Document 10).

Japanese Patent Laid-Open No. 7-213398 Japanese Patent Laid-Open No. 10-130869 JP-A-6-304857 JP-A-8-2193 JP-A-10-166798 Japanese Patent Laid-Open No. 10-202818 JP 2005-223187 A JP 2006-328227 A JP 2009-235272 A JP 2008-30474 A

  However, it is difficult to form a high-definition masking layer having a line width of 1 mm or less with an adhesive sheet. Moreover, since the cutting process and bonding process of an adhesive sheet are needed, productivity is inferior compared with the method of forming a masking layer by screen printing.

  Moreover, in the method of masking by screen-printing oxidative polymerization type ink etc., a screen printing plate is required. For this reason, it is difficult to apply to printing with a small number of lots, and also causes an increase in cost. Furthermore, there is a problem that VOC occurs during printing and plate cleaning. In addition, even the methods described in Patent Documents 8 to 10 cannot achieve both sufficient adhesion to the metal plate and sufficient UV curability.

  An object of the present invention is for surface processing that has sufficient adhesion to a metal plate, has impact resistance capable of surface processing such as mechanical polishing and shot blasting, and is formed with a high-definition partial resin film The object is to provide a resin-coated metal plate and a method for producing the same.

  Moreover, the subject of this invention is providing the manufacturing method of the metal decorative board which can respond to a design change easily, is excellent in workability | operativity, and can perform high-definition processing.

  The present inventors can achieve the above object by forming a resin film having a predetermined yield stress and a predetermined thickness using an inkjet ink composition containing an appropriate amount of a polymerizable phosphate ester compound. The inventors have found that this is possible and have completed the present invention.

  That is, according to the present invention, there are provided the following resin-coated metal sheet for surface processing, a method for manufacturing a resin-coated metal sheet for surface processing, and a method for manufacturing a metal decorative sheet.

[1] A metal plate and a resin film made of a cured product of an ink composition that covers a part of the surface of the metal plate,
The ink composition contains a polymerizable monomer that can be polymerized by active energy rays and a photopolymerization initiator, and has a viscosity at 25 ° C. of 3 to 50 mPa · s,
0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass is in the molecule. A monofunctional monomer having one ethylenic double bond group and no phosphate ester group;
A resin-coated metal sheet for surface processing, wherein the resin film has a thickness of 5 to 80 μm, and the yield stress of the resin film is 20 MPa or more.

  [2] The resin-coated metal sheet for surface processing according to [1], wherein the polymerizable phosphate compound is a compound represented by any one of the following general formulas (A1) to (A4).

［式中、Ｒは水素原子又はメチル基を表し、Ｒ_１は炭素数が１〜４のアルキレン基を表す］

［式中、ＲとＲ_１はそれぞれ前記一般式（Ａ１）と同様に定義される］

［式中、ＲとＲ_１はそれぞれ前記一般式（Ａ１）と同様に定義され、Ｒ_２は炭素数が１〜１０のアルキレン基を表す］

［式中、Ｒ、Ｒ_１およびＲ_２はそれぞれ前記一般式（Ａ３）と同様に定義される］

[Wherein, R represents a hydrogen atom or a methyl group, and R ₁ represents an alkylene group having 1 to 4 carbon atoms]

[Wherein, R and R ₁ are defined as in the general formula (A1), respectively]

[Wherein, R and R ₁ are each defined in the same manner as in the general formula (A1), and R ₂ represents an alkylene group having 1 to 10 carbon atoms]

[Wherein, R, R ₁ and R ₂ are defined in the same manner as in the general formula (A3)]

  [3] The photopolymerization initiator is composed of an acyl phosphine oxide-based initiator and an α-hydroxyketone initiator having one or less phenyl groups in the skeleton. ] The resin-coated metal plate for surface processing as described in the above.

  [4] 10 to 75% by mass of the polymerizable monomer is a polyfunctional monomer having two or more ethylenic double bond groups in the molecule and having no phosphate ester group. The resin-coated metal sheet for surface processing according to any one of 1] to [3].

[5] Forming a resin film by patterning and coating the ink composition on a metal plate by an inkjet method, and curing the patterned coating material of the ink composition by irradiation with active energy rays from a metal halide lamp doped with gallium. A process for producing a resin-coated metal sheet for surface processing comprising the steps of:
The resin film has a thickness of 5 to 80 μm and a yield stress of 20 MPa or more;
The ink composition contains a polymerizable monomer that can be polymerized by the active energy ray, and a photopolymerization initiator, and has a viscosity at 25 ° C. of 3 to 50 mPa · s,
0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass is in the molecule. The manufacturing method which is a monofunctional monomer which has one ethylenic double bond group, and does not have a phosphate group.

  [6] A step of mechanically polishing and / or blasting the surface of the resin-coated metal plate for surface processing according to any one of [1] to [4], which is not coated with the resin film. And a step of removing the resin film from the metal plate.

  On the surface of the resin-coated metal plate for surface processing of the present invention, a resin film having sufficient adhesion to the metal plate and having excellent impact resistance is patterned. Moreover, the resin film formed on the surface of the resin-coated metal plate for surface processing of the present invention is formed by printing and curing a predetermined ink composition by an ink jet printing method. For this reason, it is possible to produce a high-definition and excellent design decorative metal plate by subjecting the resin-coated metal plate for surface processing of the present invention to surface processing such as mechanical polishing or shot blasting.

  In the present invention, the coated material is cured with active energy rays while the ink composition is coated by an ink jet method, so that a photosensitive resist mask and a screen printing plate are not required. Further, it can be directly printed on a metal plate and masked from CAD and various image data, and VOC is not generated. For this reason, the metal decorative plate manufacturing method of the present invention is suitable for small lot production and multi-type production because it is excellent in workability and can easily cope with design changes.

It is a graph which shows a contact pressure-strain curve. It is a schematic diagram which shows an example of UV irradiation apparatus. It is a schematic diagram which shows a part of measuring method of the yield stress of a resin film. It is a schematic diagram which shows an example of a vibration grinding | polishing apparatus.

1. Resin-coated metal plate for surface processing The resin-coated metal plate for surface processing of the present invention (hereinafter also simply referred to as “resin-coated metal plate”) comprises (1) a metal plate and (2) a part of the surface of the metal plate. And a resin film to be coated. And the yield stress of a resin film is 20 Mpa or more, and the thickness of a resin film is 5-80 micrometers. Hereinafter, details of the resin-coated metal plate of the present invention will be described.

(1) Metal plate The metal plate is not particularly limited as long as its surface can be processed by a processing method such as mechanical polishing or blasting. Examples of the metal plate include austenitic stainless steel such as SUS304 and SUS316; and ferritic stainless steel such as SUS410 and SUS430. For applications where mechanical strength is required, use austenitic or ferritic stainless steel work-hardened material, martensitic stainless steel plate such as SUS420, or precipitation strengthened stainless steel plate such as SUS631. Is preferred. In addition to the stainless steel plate, copper, carbon steel, or iron-nickel alloy may be used.

  Moreover, it is preferable that the metal plate is surface-finished which improves designability. For example, in the case of a stainless steel plate, a BA finish for increasing glossiness, a mirror finish such as No8, and a hairline finish such as HL may be applied.

(2) Resin film The resin film covers a part of the surface of the metal plate. For this reason, the surface of a metal plate has the non-processed surface covered with the resin film, and the process surface not covered with the resin film. The resin film has impact resistance against surface processing such as mechanical polishing and shot blasting, and has a function as a masking layer.

(2-1) Yield Stress of Resin Film Conventionally, an ink composition used as a constituent material for a masking layer for shot blasting is a rubber having excellent impact resistance in order to improve the impact resistance of the masking layer. System resin is added. However, it is difficult to apply a high-viscosity ink composition to which a rubber-based resin is added by an inkjet method. On the other hand, in the present invention, although it is a masking layer (resin film) formed by applying an ink composition by an ink jet method, it has the same wear resistance and impact resistance as when a rubber-based resin is used. A masking layer (resin film) having excellent properties can be formed. That is, in the present invention, paying attention to the yield stress having a correlation with the degree of cure, the yield stress is set to a predetermined value or more by increasing the degree of cure of the resin film. As a result, a resin-coated metal plate capable of surface processing such as mechanical polishing and shot blasting was realized.

  The yield stress of the resin film constituting the resin-coated metal plate of the present invention is 20 MPa or more, preferably 40 MPa or more, more preferably 60 MPa or more. By setting the yield stress of the resin film to 20 MPa or more, impact resistance to surface processing such as mechanical polishing and shot blasting is exhibited. The upper limit of the yield stress of the resin film is not particularly limited, but may be substantially 100 MPa or less. The yield stress of the resin film is adjusted, for example, by the type and composition ratio of the polymerizable monomer contained in the ink composition, the type and composition ratio of the photopolymerization initiator, or the irradiation conditions (integrated light amount, etc.) of the active energy ray. It can be adjusted by doing.

The yield stress of the resin film can be measured by a spherical nanoindentation method without peeling the resin film from the metal plate. The spherical nanoindentation method is a method of quantifying the hardness and elastic modulus of the outermost surface micro-part layer to be measured from the load-displacement curve obtained by pushing the spherical indenter into the measurement object with an extremely small load. . In Hertz's contact theory, the relationship between the average contact pressure P _m and the composite elastic modulus _Er is expressed by the following equation.

In the above formula, h represents the indentation depth, and R represents the tip pole radius of the spherical indenter. The contact area A _p of the spherical indenter and the measurement object can be approximated as "A _{p =} PaiRh". Therefore, when the load is P, the average pressure P _m is expressed by the following formula. That is, by applying the law of Hook relative weighting displacement curve generated using a spherical pressure of tip curvature radius R, "contact pressure" and P _m and the (h / R) ^0.5 and "distortion" It can be converted to a contact pressure-strain curve.

  The “yield stress” in the present invention is a pressure deviating from an elastic curve (contact pressure-strain curve) drawn from the analyzed composite elastic modulus after analyzing the composite elastic modulus by a spherical nanoindentation method using a Berkovich indenter. .

(2-2) Thickness of Resin Film The thickness (total film thickness) of the resin film is 5 to 80 μm, preferably 10 to 80 μm, and more preferably 20 to 60 μm. When the thickness of the resin film is less than 5 μm, the impact resistance is insufficient, and the resin film is easily peeled off by surface processing such as mechanical polishing or shot blasting. On the other hand, if the thickness of the resin film exceeds 80 μm, it is difficult to obtain sufficient resolution, and fine patterning becomes difficult. The thickness of the resin film can be controlled, for example, by adjusting the number of printings by the ink jet method.

(3) Ink composition The resin film is a cured product obtained by curing the ink composition with active energy rays. The ink composition contains a polymerizable monomer that can be polymerized by active energy rays and a photopolymerization initiator. And 0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass of the polymerizable monomer is a molecule. It is a monofunctional monomer having one ethylenic double bond group therein and no phosphate ester group.

(3-1) Polymerizable phosphate ester compound The polymerizable phosphate ester compound is a compound having a phosphate ester group and an ethylenic double bond group in the molecule. A compound having a phosphate group is likely to improve metal adhesion as compared with a compound having a carboxyl group. Therefore, even an ink composition containing a small amount of a polymerizable phosphate ester compound has sufficient metal adhesion. An ink composition containing a small amount of a polymerizable phosphoric ester compound has an advantage that it can be stably ejected and applied by inkjet since the viscosity does not increase excessively.

The phosphate ester group refers to a group represented by any of the following formulas (a1) to (a3). As the phosphate group, a group represented by the formula (a2) or the formula (a3), a so-called acidic phosphate group is preferable. This is because these groups have a phosphoric acid group, so that they undergo a condensation reaction with a hydroxyl group present on the metal surface to improve adhesion to the metal. The composition containing a compound having a group represented by the formula (a3) gives a resin film particularly excellent in adhesion to a metal. Moreover, the composition containing the phosphate ester group represented by the formula (a2) has an advantage that the viscosity is extremely low. Therefore, the structure of the phosphate ester group may be appropriately selected according to the intended physical properties.

  The ethylenic double bond group refers to a group having a carbon-carbon double bond. The ethylenic double bond group may have a substituent. Examples of the ethylenic double bond group include (meth) acryloyl group, vinyl group and vinylidene group. Especially, since acquisition is easy, it is preferable that an ethylenic double bond group is a (meth) acryloyl group. The (meth) acryloyl group means a methacryloyl group or an acryloyl group. Therefore, the polymerizable phosphoric acid ester compound is preferably a compound obtained by esterifying a compound having a (meth) acryloyl group and a hydroxyl group in the molecule with phosphoric acid.

Examples of compounds having a (meth) acryloyl group and a hydroxyl group in the molecule include the following.
2-hydroxymethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, etc. Hydroxyalkyl (meth) acrylate.

  (Poly) ethylene glycol (meth) acrylates such as ethylene glycol (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, and tetraethylene glycol (meth) acrylate.

Especially, the compound represented by the following general formula (A1)-(A4) is preferable as a polymerizable phosphate ester compound. This is because it is easy to improve the adhesion of the resin film to the metal and it is easy to obtain.

In the formula (A1), R represents a hydrogen atom or a methyl group, and R ₁ represents an alkylene group having 1 to 4 carbon atoms. R is preferably a methyl group in order to reduce the viscosity of the compound. R ₁ is preferably an ethylene group in order to improve the balance between adhesion to metal and alkali peelability. A compound in which R ₁ is an ethylene group is also called 2- (meth) acryloyloxyethyl acid phosphate or 2- (meth) acryloyloxyethyl phosphate.

In the formula (A2), R independently represents a hydrogen atom or a methyl group, and R ₁ independently represents an alkylene group having 1 to 4 carbon atoms. “Independently” means that two or more R or R ₁ may be the same or different from each other. R is preferably a methyl group in order to reduce the viscosity of the compound. R ₁ is preferably an ethylene group in order to enhance the adhesion and solubility of the compound with the metal. The compound in which R ₁ is an ethylene group is also called di {2- (meth) acryloyloxyethyl} acid phosphate or di-2- (meth) acryloyloxyethyl phosphate.

In the formula (A3), R each independently represents a hydrogen atom or a methyl group, R ₁ represents an alkylene group having 1 to 4 carbon atoms, and R ₂ represents an alkylene group having 1 to 10 carbon atoms. R is preferably a methyl group in order to reduce the viscosity of the compound. R ₁ is preferably an ethylene group in order to enhance the adhesion between the compound and the metal, and R ₂ is preferably a pentene group.

In formula (A4), each R independently represents a hydrogen atom or a methyl group, each R ₁ independently represents an alkylene group having 1 to 4 carbon atoms, and each R ₂ independently represents 1 to 10 carbon atoms. Represents an alkylene group. R is preferably a methyl group in order to reduce the viscosity of the compound. R ₁ is preferably an ethylene group in order to increase the balance between the adhesion and solubility of the compound with the metal, and R ₂ is preferably a pentene group.

  0.5-13 mass% of the polymerizable monomers contained in the ink composition is a polymerizable phosphate ester compound. When the content of the polymerizable phosphoric ester compound is less than 0.5% by mass, the adhesion of the cured product of the ink composition (hereinafter also referred to as “cured film”) to the metal becomes insufficient. For this reason, the impact resistance of the resin film is lowered, and the resin film is easily lost or peeled off by surface processing such as mechanical polishing or shot blasting, so that the function as a masking layer cannot be maintained. When the content exceeds 13% by mass, not only the physical strength of the resin film (scratch hardness (pencil method)) is not sufficient, but also the viscosity of the ink composition at 25 ° C. exceeds 50 mPa · s, There is a high possibility that the ink jet method cannot be ejected. Since the cured film has excellent adhesion and physical strength (scratch hardness (pencil method)) and can maintain an appropriate viscosity range of the ink, the content of the polymerizable phosphate ester compound is 4 to 13 masses. % Is more preferable.

  Since the ink composition contains a polymerizable phosphoric ester compound, the cured film of the ink composition formed on the surface of the metal plate can be peeled off by a simple technique such as immersing in an alkaline aqueous solution.

(3-2) Multifunctional monomer The ink composition preferably includes a polyfunctional monomer having two or more ethylenic double bond groups in the molecule and having no phosphate group. Of the polymerizable monomers contained in the ink composition, 10 to 75% by mass, preferably 55 to 65% by mass, are polyfunctional monomers.

  Examples of the polyfunctional monomer include compounds containing 2 to 6 ethylenic double bond groups in the molecule. Especially, as a polyfunctional monomer, the compound which has a 2 or more (meth) acryloyl group in a molecule | numerator is preferable. This is because it is easily available and is easily polymerized by active energy rays. When the ink composition contains a polyfunctional monomer, the crosslinking density is further improved, and the strength of the cured film is further improved. However, if the polyfunctional monomer is added too much, the crosslinking density becomes too high, and the adhesiveness may decrease due to the curing shrinkage of the cured film. Therefore, the content of the polyfunctional monomer is preferably set in an appropriate amount from the balance between the physical strength of the cured film and the solubility of the photopolymerization initiator.

A known polyfunctional monomer may be used. However, in the present invention, it is preferable to use a compound represented by the following general formula (B1) or (B2).

In general formula (B1), R represents a hydrogen atom or a methyl group each independently. R < ₁₀ > represents a C1-C5 alkyl group each independently. P represents the number of R ₁₀ substituted on the benzene ring and is an integer of 0 to 4. X represents a single bond, a methylene group, or an isopropylidene group, and n and m each represents a number of 0 to 6. Such a compound is available as (meth) acrylate of ethylene glycol-modified bisphenol. Such a compound can be obtained by reacting bisphenol modified with ethylene glycol and acrylic acid. n + m is preferably 3 to 5, and more preferably 4.

In the general formula (B2), R each independently represent a hydrogen atom or a methyl group, R ₂₀ represents an alkylene group having 3-9 carbon atoms. The alkylene group having 3 to 9 carbon atoms is preferably a hexyl group or a pentyl group.

(3-3) Monofunctional monomer The ink composition contains a monofunctional monomer having one ethylenic double bond group and no phosphate group in the molecule. Examples of the monofunctional monomer include the following compounds.

  2-phenoxyethyl acrylate, acryloylmorpholine, N-vinylcaprolactam, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, isobutyl acrylate, t-butyl acrylate, isooctyl acrylate, isobornyl acrylate, Cyclohexyl acrylate, 2-methoxyethyl acrylate, methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate, tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate, benzyl acrylate, ethoxyethyl acrylate, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydipropylene Glycol acrylate, methylphenoxy ethyl Acrylate, dipropylene glycol acrylate.

  Especially, as a monofunctional monomer, the compound which contains a (meth) acryloyl group in a molecule | numerator is preferable. This is because it is easily available and is easily polymerized by active energy rays.

  A monofunctional monomer may be used independently and may use multiple types together. Ink compositions containing these monofunctional monomers exhibit low viscosity and can be stably ejected by inkjet. 10-75 mass% of the polymerizable monomers contained in the ink composition is a monofunctional monomer. If the content of the monofunctional monomer is less than 10% by weight, the resulting ink composition has a high viscosity, which may make it difficult to eject by ink jet. When the content exceeds 75% by weight, the physical strength (scratch hardness (pencil method)) of the cured film may be lowered. For this reason, the impact resistance of the cured film is lowered, and the cured film is likely to be lost or peeled off by surface processing such as mechanical polishing or shot blasting, and the function as a masking layer may not be maintained.

(3-4) Carboxyl group-containing polymerizable compound The ink composition preferably contains 1 to 30% by mass of the carboxyl group-containing polymerizable compound represented by the following general formula (I) in all monomers.

  In general formula (I), X represents an alkylene group having 1 to 3 carbon atoms, Y represents an alkylene group having 2 or 3 carbon atoms, and R represents a hydrogen atom or a methyl group.

  The carboxyl group-containing polymerizable compound represented by the general formula (I) gives a cured product having excellent adhesion to metal, etching resistance, and alkali peelability. The adhesion to the metal is considered to be improved because the carboxyl group of the carboxyl group-containing polymerizable compound reacts with a hydroxyl group or the like present on the metal surface. It is considered that the etchant resistance is improved by the carboxyl group-containing polymerizable compound having a stable chemical structure with respect to the etchant and forming a cross-linked structure with other monomers to give a hardened product. The alkali peelability is considered to be improved by the hydrolysis of the carboxyl group of the carboxyl group-containing polymerizable compound or the ester group derived therefrom with an alkali.

Further, the carboxyl group-containing polymerizable compound is likely to associate in the molecule as shown by the following general formula (1). Therefore, unlike a compound having a general carboxyl group, it is difficult to form a dimer (see the following general formula (2)) with other molecules. Therefore, the carboxyl group-containing polymerizable compound can be used even if a sufficient amount is added to the ink composition in order to sufficiently improve the adhesion between the cured product and the metal, the etching solution resistance, and the alkali peelability. The viscosity of the composition is difficult to increase.

  In the formulas (1) and (2), Z represents an arbitrary organic group, and X represents an alkylene group having 1 to 3 carbon atoms.

  In the general formula (I), when X is a methylene group, the carbonyl group and the carboxyl group are likely to approach each other, so that intramolecular association shown in the general formula (1) is likely to occur. Further, when X is an ethylene group or a propylene group, although the distance between the carbonyl group and the carboxyl group is slightly separated, intramolecular association is likely to occur because the carbon-carbon bond in the alkylene group is rotatable. On the other hand, when X is an alkylene group having 4 or more carbon atoms, the distance between the carbonyl group and the carboxyl group becomes too long, so that intramolecular association hardly occurs. Further, when X is an aromatic hydrocarbon group such as a 1,2-phenylene group, the bond between two carbons on the aromatic ring to which the carbonyl group is bonded cannot be rotated, so that intramolecular association is less likely to occur. As described above, a compound that hardly causes intramolecular association is likely to dimerize by associating with other molecules as represented by the above formula (2).

  Examples of the alkylene group having 1 to 3 carbon atoms include methylene group, ethylene group, propylene group, isopropylene group and isopropylidene group. Among these, X is preferably a methylene group or an ethylene group, and particularly preferably an ethylene group, because intramolecular association is likely to occur. In the carboxyl group-containing polymerizable compound, a compound in which X is a methylene group is also called a malonic acid ester compound, a compound in which X is an ethylene group is also called a succinic acid ester compound, and a compound in which X is a propylene group is also called a glutaric acid ester compound.

  Examples of the alkylene group having 2 or 3 carbon atoms represented by Y in the general formula (I) include an ethylene group, a propylene group, an isopropylene group, and an isopropylidene group. As described above, the carboxyl group is bonded to a hydroxyl group on the metal surface, and the polymerizable functional group undergoes a polymerization reaction with another polymerizable functional group. As the number of carbon atoms in Y increases, the molecular weight between the polymerizable functional group and the carboxyl group increases, so the distance between the bonding site with the metal and the polymerization site becomes longer, and moisture easily penetrates during this time. There is. As a result, when the carbon number of Y increases, the water resistance of the cured product may decrease. For this reason, Y is preferably an ethylene group. R is a hydrogen atom or a methyl group.

  Specific examples of the carboxyl group-containing polymerizable compound include 2-acryloyloxyethyl succinic acid, 2-methacryloyloxyethyl succinic acid, 2-acryloyloxypropyl succinic acid, 2-acryloyloxyethyl malonic acid, and 2 -Acrylroyoxyethyl glutaric acid is included.

  The viscosity of 2-acryloyloxyethyl succinic acid at 25 ° C. is 180 mPa · s. The viscosity of 2-methacryloyloxyethyl succinic acid at 25 ° C. is 160 mPa · s. On the other hand, the viscosity at 25 ° C. of 2-acryloyloxyethyl hexahydrophthalic acid which is a polymerizable compound not included in the general formula (I) is about 4000 mPa · s, which is higher than the viscosity of the carboxyl group-containing polymerizable compound. high. The viscosity of these compounds is measured at 25 ° C. with a cone plate viscometer. A known cone plate viscometer may be used. The measurement conditions are preferably a shear rate: 230 (1 / s) and a rotation speed: 60 rpm.

  Some carboxyl group-containing polymerizable compounds are commercially available, but may be synthesized. The carboxyl group-containing polymerizable compound is, for example, (1) a step of reacting a dicarboxylic acid such as succinic acid with a diol such as ethylene glycol to obtain a monoester, (2) a monoester obtained in the previous step, acrylic acid or And a step of reacting methacrylic acid. Each step may be performed by a regular method.

  1-30 mass% of the polymerizable monomers contained in an ink composition, Preferably 1-10 mass% is a carboxyl group-containing polymeric compound.

(3-5) Photopolymerization initiator The ink composition contains a photopolymerization initiator. The type of the photopolymerization initiator is not particularly limited as long as it is a component capable of initiating polymerization of a polymerizable monomer that is also contained in the ink composition. However, the photopolymerization initiator preferably includes an acyl phosphine oxide initiator and an α-hydroxyketone initiator having one or less phenyl groups in the skeleton; an acyl phosphine oxide initiator. More preferably, it comprises an agent and an α-hydroxyketone initiator having one or less phenyl groups in the skeleton. The reason will be described below.

  The α-hydroxyketone initiator contributes to the improvement of the surface curability of the photocurable ink composition. For this reason, when an α-hydroxyketone-based initiator is used as a photopolymerization initiator, the surface curability of each ink droplet is improved. On the other hand, the acylphosphine oxide-based initiator has an absorption region on the long wavelength side as compared with the α-hydroxyketone-based initiator, and thus contributes to the improvement of the internal curability of the photocurable ink composition. For this reason, when an acylphosphine oxide-based initiator is used as a photopolymerization initiator, the internal curability of the thick film formed by overlapping ink droplets is improved.

  In addition, photopolymerization initiators other than acylphosphine oxide initiators and α-hydroxyketone initiators are often not suitable as the photopolymerization initiator of the present invention. For example, an amine photoinitiator added as a general means for improving polymerization inhibition by oxygen and obtaining sufficient UV curability reacts with a polymerizable phosphate ester compound to form a salt. To precipitate. For this reason, the amine photoinitiator aid cannot be used in combination with the polymerizable phosphate compound. For the same reason, α-aminoketone initiators cannot be used to react with the polymerizable phosphate compound. Since these basic polymerization initiators and photoinitiator aids cannot be used, the types of polymerization initiators that can be used are greatly limited.

  In contrast, the combined use of an acylphosphine oxide initiator and an α-hydroxyketone initiator can be used because it does not form a salt with the polymerizable phosphate compound. However, an α-hydroxyketone initiator having two or more phenyl groups contained in the skeleton is hardly compatible with other ink components, so that the viscosity of the obtained ink composition is excessively increased. Furthermore, the α-hydroxyketone initiator having two or more phenyl groups contained in the skeleton has an ink composition as compared with the α-hydroxyketone initiator having one or less phenyl groups in the skeleton. Low solubility in products. For this reason, it is difficult to add a sufficient amount of an α-hydroxyketone initiator having two or more phenyl groups contained in the skeleton to the ink composition for inkjet.

  Therefore, in the present invention, an α-hydroxyketone initiator having one or less phenyl groups in the skeleton is used as a component constituting the photopolymerization initiator together with the acylphosphine oxide initiator. By using an α-hydroxyketone initiator having one or less phenyl groups in the skeleton instead of an α-hydroxyketone initiator having two or more phenyl groups in the skeleton, a sufficient amount can be obtained. Even when a polymerizable phosphoric acid ester compound is added, an ink composition having an appropriate viscosity that can be ejected for inkjet use can be obtained without excessively increasing the viscosity. It is preferable that the ink composition does not substantially contain an α-hydroxyketone initiator having 2 or more phenyl groups in the skeleton.

Examples of the acylphosphine oxide initiator include the following compounds.
Bis (2,4,6-trimethylbenzyl) -phenylphosphine oxide (trade name “Irgacure 819” manufactured by BASF), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (trade name “manufactured by BASF” Darocur TPO ").

Examples of the α-hydroxyketone photopolymerization initiator in which the number of phenyl groups contained in the skeleton is 1 or less include the following compounds.
2-hydroxy-2-methyl-1-phenylpropan-1-one (trade name “Darocur 1173” manufactured by BASF), 4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone ( BASF, trade name “Irgacure 2959”), 1-hydroxycyclohexyl-phenyl ketone (BASF, trade name “Irgacure 184”).

  The addition amount of the photopolymerization initiator is preferably 1.0 to 20.0% by mass, and more preferably 10.0 to 17.0% by mass with respect to the ink composition. When the addition amount of the photopolymerization initiator is less than 1.0% by mass, the ink composition tends not to be sufficiently cured. On the other hand, when the addition amount of the photopolymerization initiator exceeds 20.0% by mass, the viscosity of the ink composition tends to increase excessively, and it may be difficult to discharge from the inkjet head.

  The content mass ratio between the acylphosphine oxide initiator (A) and the α-hydroxyketone photopolymerization initiator (B) in which the number of phenyl groups contained in the skeleton is 1 or less is (A) / ( B) = 2/1 to 1/3 is preferable, and (A) / (B) = 1/1 to 1/2 is more preferable. By setting the content ratio of the components to the above range, both the surface curability and the internal curability of the ink composition can be achieved.

(3-6) Other additives Furthermore, the ink composition is a compound other than the above and not reacting with other components, a resin, an inorganic filler, an organic filler, a coupling agent, if necessary. A tackifier, an antifoaming agent, a leveling agent, a plasticizer, an antioxidant, a polymerization inhibitor, an ultraviolet absorber, a flame retardant, a pigment, or a dye can be appropriately used in combination.

  The ink composition is not particularly required to be colored, but may be colored for confirmation of printing quality such as pinhole check. The color pigment that can be used in that case is not particularly limited.

  The ink composition does not substantially require a solvent. For example, ketones such as methyl ethyl ketone and methyl isobutyl ketone, acetates such as ethyl acetate and butyl acetate, aromatic hydrocarbons such as benzene, toluene and xylene, , Ethylene glycol monoacetate, propylene glycol monomethyl ether, alcohols such as butyl alcohol, and other commonly used organic solvents may be included.

(3-7) Viscosity The viscosity of the ink composition at 25 ° C. is preferably 3 to 50 mPa · s. Further, the ink composition generally has a viscosity of 3 to 35 mPa · s, more preferably 7 to 20 mPa · s, at 25 to 80 ° C., which is generally a discharge temperature in inkjet. An ink composition having a viscosity within the above temperature range is excellent in ejection stability. That is, the ink composition used in the present invention can be printed by being ejected onto a metal plate by an inkjet method. For this reason, a resin film (cured film) that functions as a masking layer with high definition and high designability can be formed on the surface of the metal plate.

  When the viscosity at 25 ° C. of the ink composition is less than 3 mPa · s, a decrease in ejection followability may be observed in a high-frequency piezoelectric inkjet head of 10 to 50 kHz. If the viscosity at 25 ° C. exceeds 50 mPa · s, ejection may become unstable even if the heating device is arranged in an inkjet head. The viscosity of the ink composition can be adjusted mainly by the content of the polymerizable phosphate compound. The viscosity is preferably measured with a cone plate viscometer.

(3-8) Surface tension The surface tension of the ink composition is preferably 20 to 40 mN / m. The surface tension affects the ejection properties from the inkjet head and the resolution when drawing a pattern on a metal plate. An ink composition having a surface tension in the above range is excellent in dischargeability and the resolution. The surface tension is adjusted by a known method such as adding various surfactants. The surface tension may be measured by a known method, for example, a hanging drop method or a ring method, but is preferably measured by a plate method. For example, the surface tension can be measured using a trade name “CBVP-Z type” manufactured by Kyowa Interface Science Co., Ltd.

(3-9) Method for Producing Ink Composition The ink composition is produced by dispersing or dissolving each component using a mixer, a disperser, and a stirrer. As a stirring mixer, a propeller type stirrer, a dissolver, a homomixer, a ball mill, a sand mill, an ultrasonic disperser, a kneader, a line mixer, and the like can be used. Dispersers include propeller type stirrers, piston type high pressure emulsifiers, homomixers, ultrasonic emulsifier dispersers, pressure nozzle emulsifiers, high speed rotating high shear type stirrers, colloid mills, media type dispersers, etc. Can be used. The media type disperser is an apparatus that performs pulverization and dispersion using a medium such as glass beads and steel balls. Examples include sand grinders, agitator mills, ball mills and attritors. These dispersers may be used in combination of two or more. Also, a stirring mixer can be used in combination. The ink composition can be filtered with a filter having a pore size of 3 μm or less, preferably 1 μm or less.

2. Method for Producing Resin-Coated Metal Plate By using the ink composition described above, the resin-coated metal plate of the present invention in which the metal plate is partially coated with a resin film can be produced. The resin-coated metal plate may be arbitrarily produced as long as the effects of the present invention are not impaired, but a preferable method will be described below. The resin-coated metal plate is a method comprising: (a) a step of patterning and applying an ink composition to a metal plate by an inkjet method; and (b) a step of curing the patterning coating material of the ink composition by irradiation with active energy rays. It is preferable to be manufactured.

  In the step (a), the ink composition is discharged and applied to the surface of the metal plate using a normal ink jet recording apparatus. The ink jet recording apparatus preferably includes an ink composition supply unit, a temperature sensor, and an active energy ray irradiation unit. The ink composition supply means preferably includes an original tank for filling the ink composition, a supply pipe, an ink supply tank disposed in front of the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head is preferably a multidot of 1 to 100 pl. The resolution is preferably 320 × 320 to 4000 × 4000 dpi. The dpi is the number of dots per 2.54 cm.

  The discharge of the ink composition is preferably performed while heating the ink composition in the inkjet head to 35 to 100 ° C. The image quality of printing by the ink jet method is affected by a change in the viscosity of the ink composition due to a temperature change. Therefore, it is preferable to keep the temperature constant while raising the temperature of the ink composition. The control range of the temperature of the ink composition is preferably ± 5 ° C. with respect to the set temperature, more preferably ± 2 ° C., and further preferably ± 1 ° C.

  In printing by the ink jet method, ink droplets are usually ejected and applied to the same location in a superimposed manner. In this case, it is preferable to irradiate an active energy ray every time an ink droplet is ejected to cure (pre-bake) each ink droplet. Thereby, the prebaked ink composition can be superimposed and a thick cured film can be formed.

The active energy rays are preferably irradiated by 0.01 to 2.0 seconds after the ink droplets adhere to the metal plate, and more preferably by 0.01 to 1.0 seconds. preferable. By making the irradiation timing earlier, a high-definition image can be formed. Moreover, it is preferable to use an active energy ray having a maximum illuminance of 500 to 6000 mW / cm ² in a wavelength range effective for curing.

  In the step (b), an active energy ray is applied to the coating film applied by the ink jet method to cure (mainly bake) the ink composition. Thereby, it hardens even to the inside of the coating film which consists of an ink composition. Active energy rays refer to infrared rays, visible rays, ultraviolet rays, X-rays, electron beams, alpha rays, beta rays, gamma rays, and the like. Preferred examples of the active energy ray source include a mercury lamp, a low pressure mercury lamp, various metal halide lamps, a low pressure / solid state laser, a xenon flash lamp, a black light, a germicidal lamp, a cold cathode tube, a light emitting diode (LED) and a laser diode (LD). ) Is included.

  A preferable active energy ray source is a lead-based metal halide lamp, an iron-based metal halide lamp, or a gallium-based metal halide lamp that emits light with a wavelength of 380 to 450 nm. A gallium metal halide lamp that strongly emits light having a wavelength of 400 to 430 nm is particularly preferable because the internal curability of the cured film (resin film) becomes good. In addition, GaN-based ultraviolet LEDs and ultraviolet LDs are preferable from the viewpoint of environmental protection because they do not use mercury. The ultraviolet LED is small, has a long life, is highly efficient, and is low in cost, and is expected as a light source for photo-curable ink jet.

A preferable active energy ray preferably has a maximum illuminance of 500 to 6000 mW / cm ² in a wavelength range effective for curing.

FIG. 2 is a schematic diagram illustrating an example of a UV irradiation apparatus. As shown in FIG. 2, the UV irradiation device 20 includes a UV lamp 12 and a reflection plate 16 that covers the opposite side of the irradiation direction of the UV lamp 12. In the step (b), the coating film 24 made of the ink composition formed in the step (a) is cured to the inside. For this purpose, it is preferable to place the metal plate on which the coating film 24 is formed on the conveyor 30 and irradiate the coating film 24 with the UV light 18 while transporting the metal plate at a speed of 1 to 50 m / min. Also, repeatedly irradiated with UV light 18, preferably the integrated light quantity is 800~20000mJ / cm ^2, more preferably by a 2000~18000mJ / cm ^2, given the yield stress of the cured film (resin film) formed Or more. The integrated light amount is measured using an ultraviolet illuminometer / light meter (trade name: UV351-42 manufactured by Oak Manufacturing Co., Ltd.) having a measurement wavelength region of 340 to 490 nm and a measurement wavelength center of 420 nm.

  In the ink composition of the present invention, the α-hydroxyketone-based initiator that contributes to the improvement of the surface curability of the ink coating and the acylphosphine oxide-based initiator that contributes to the improvement of the internal curability. Contains a photopolymerization initiator. Therefore, a thick coating film can be formed while curing the surface of the ink droplets ejected in the step (a), and the inside of the coating film formed in the step (b) can be sufficiently cured.

  (B) You may heat-process a cured film (resin film) as needed after a process. Adhesion may be improved by effects such as internal stress relaxation of the cured film (resin film).

3. Manufacturing method of metal decorative plate If the resin-coated metal plate of the present invention is used, a metal decorative plate having a processed surface subjected to surface processing and a non-processed surface not subjected to surface processing on the same surface is manufactured. can do. The metal decorative plate includes (1) a step of processing the surface of the above-described resin-coated metal plate that is not coated with the resin film, and (2) a step of removing the resin film from the metal plate. Preferably it is manufactured by a method.

  As described above, the surface of the metal plate constituting the resin-coated metal plate has a non-processed surface covered with the resin film and a process surface not covered with the resin film. (1) In the step, the surface to be processed that is not covered with the resin film is processed among the surface of the metal plate. Examples of the method for processing the surface to be processed include mechanical polishing and blasting. A plurality of processing methods may be combined.

  Specific examples of the mechanical polishing include hairline polishing and vibration polishing. Hairline polishing is a polishing method in which long and continuous polishing eyes are formed on the surface of the metal plate by rubbing the abrasive on the surface of the metal plate in one direction or reciprocatingly. As the abrasive, non-woven pads, cloths, felts, buffs obtained by applying an abrasive to skin, etc. can be used.

  Vibration polishing (multi-axis horizontal polishing) is a polishing method in which an infinite number of non-directional thread-like polishing eyes are formed on the surface of a metal plate by repeatedly rubbing an abrasive on the surface of the metal plate in a random direction. It is. As an abrasive, the same one used in hairline polishing can be used.

  As a specific example of the blasting process, a shot blasting process in which irregularities are formed by polishing the surface of the metal plate by spraying a shot material (abrasive grains) on the surface of the metal plate can be exemplified. As the shot material, glass beads, steel shots, steel grids, cut wires, silica sand, alumina and the like can be used.

  In the step (2), after the processed surface of the metal plate is processed, the resin film functioning as the masking layer is removed. By removing the resin film, a metal decorative plate having a processed surface (design surface) subjected to a desired surface processing and a non-processed surface (glossy surface) not subjected to surface processing in the same plane Can be obtained.

  The method for removing the resin film is not particularly limited, and the resin film can be mechanically peeled off. However, since the resin film of the resin-coated metal plate of the present invention is alkali-soluble, it is preferable to dissolve or peel it off using an alkaline aqueous solution because it can be easily and massively processed. As the alkali component contained in the alkaline aqueous solution, sodium hydroxide, potassium hydroxide, or the like can be used. The pH of the alkaline aqueous solution is usually about 14. Moreover, the temperature of aqueous alkali solution should just be about 30-80 degreeC normally.

The following polymerizable monomer and photopolymerization initiator were prepared.
[Compound of Formula (A1)]
2-Methacryloyloxyethyl acid phosphate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester P-1M”)
[Compound of Formula (A2)]
Di (2-methacryloyloxyethyl) acid phosphate (manufactured by Kyoeisha Chemical Co., Ltd., trade name “Light Ester P-2M”)

[Multifunctional monomer]
Tripropylene glycol diacrylate (trade name “anilox M-220” manufactured by Toagosei Co., Ltd.)
EO-modified bisphenol A diacrylate n + m≈4 (Kyoeisha Chemical Co., Ltd., trade name “Light acrylate BP-4EA”, ethylene oxide unit repeat number n + m is about 4 diacrylate)

[Monofunctional monomer]
Dodecyl Acrylate (Kyoeisha Chemical Co., Ltd., trade name “Light Acrylate LA”)

[Α-hydroxyketone initiator]
1-hydroxycyclohexyl-phenyl ketone (trade name “Irgacure 184” manufactured by BASF)
2-hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by BASF, trade name “Darocur 1173”)

[Acylphosphine oxide initiator]
Bis (2,4,6-trimethylbenzyl) -phenylphosphine oxide (BASF, trade name “Irgacure 819”)
2,4,6-Trimethylbenzoyl-diphenylphosphine oxide (manufactured by BASF, trade name “Darocur TPO”)

[Example 1]
7.0 parts by weight of di (2-methacryloyloxyethyl) acid phosphate, 28.0 parts by weight of EO-modified bisphenol A diacrylate n + m≈4, 32.0 parts by weight of tripropylene glycol diacrylate, 24.0 parts by mass of dodecyl acrylate was put into a homomixer and stirred for 1 hour while heating to 35 ° C. in a dry air atmosphere under light shielding to obtain a mixture.

  To the resulting dispersion, 4.5 parts by weight of “Irgacure 184” and 4.5 parts by weight of “Irgacure 819”, which are photopolymerization initiators, are added and gently stirred until the photopolymerization initiator is dissolved. To obtain a mixture. The obtained mixture was pressure filtered through a membrane filter having a pore size of 2 μm to obtain an ink composition. The viscosity of the obtained ink composition at 25 ° C. was measured using a cone plate viscometer (trade name “TVE-22L”) manufactured by Toki Sangyo Co., Ltd.

The obtained ink composition was ejected onto the surface of 0.5 mm thick SUS304 BA using an inkjet printer equipped with one piezo-type inkjet head, and 1 cm × 1 cm solid images were spaced at 0.5 cm intervals. A plurality of drawings (printing). The mounted inkjet head was trade name “KM512SH, manufactured by Konica Minolta IJ” (droplet volume: 4 pl), or trade name “KM1024SH, manufactured by Konica Minolta IJ” (droplet volume: 6 pl)).
The conveyance speed of the metal plate during discharge was set to 555 mm / sec.

The ink droplets ejected from the inkjet head were irradiated with UV about 0.4 seconds after landing on the metal plate. Drawing by inkjet was performed by 8-pass printing, and the UV irradiation device reciprocated 8 times on the image. For irradiation, a UV irradiation apparatus (trade name “CoorArc”) manufactured by Nordson Corporation equipped with one of the following two light sources was used.
1) Gallium-based metal halide lamp (manufactured by Nordson, trade name “UV Star Gallium Lamp”, 240 W / cm)
2) High-pressure mercury lamp (trade name “UV Star Mercury Lamp”, 240 W / cm, manufactured by Nordson)

  Next, the obtained printed matter was irradiated with UV using a conveyor-type UV irradiation device (trade name “ECS-301”) manufactured by Eye Graphics, to obtain a resin-coated metal plate. The UV irradiation apparatus was equipped with a gallium metal halide lamp (high power metal halide lamp manufactured by Eye Graphics, model “MA03-L31”, 120 W / cm). The lamp output was 100%. The conveyor speed was 5 m / mim. Scanning by the conveyor was repeated 10 times, and irradiation was performed 10 times.

  Then, it heat-processed for 3 minutes in oven with an atmospheric temperature of 170 degreeC.

  The resin-coated metal plate thus obtained was evaluated as follows.

(1) Yield stress of resin film (cured film) The yield stress of the resin film was measured by the spherical nanoindentation method. Specifically, as shown in FIG. 3, the tip of a Barkovic spherical indenter 32 is pushed into the resin film 14. In this case, the contact theory of Hertz, the average pressure P _m of the contact, the relationship between the composite elastic modulus E _r, is expressed by the following equation.

In the above formula, h represents the indentation depth, and R represents the tip pole radius of the spherical indenter. The contact area A _p of the spherical indenter and the measurement object can be approximated as "A _{p =} PaiRh". Therefore, when the load is P, the average pressure P _m is expressed by the following formula. That is, by applying the law of Hook relative weighting displacement curve generated using a spherical pressure of tip curvature radius R, "contact pressure" and P _m and the (h / R) ^0.5 and "distortion" It can be converted to a contact pressure-strain curve. The pressure deviating from the obtained contact pressure-strain curve was defined as “yield stress (MPa)”.

The detailed measurement conditions for the yield stress are as follows.
Measuring device: “Nano Indenter XP / DCM” manufactured by Agilent Technologies
・ Analysis software: “Test Works 4” manufactured by Agilent Technologies
・ Measurement items: Hardness and Young's modulus ・ Indenter head: XP
Indenter: spherical indenter (curvature radius R (actual value): 6.5 μm)
・ Measurement mode: Basic (load-unloading method)
・ Maximum load load: 0.02 gf
・ Loading time: 50 seconds ・ Load holding time: 1 second ・ Unloading time: 5 seconds ・ n number: 20 times ・ Measurement point interval: 100 μm
・ Measurement temperature: Room temperature (23 ℃, use air conditioner)

(2) Cross-cut adhesion Adhesive cuts were made in accordance with JIS G3320 in the cured film on the metal plate. Next, the adhesive tape was stuck on the cured film and peeled off to observe the peeled state of the cured film. The adhesion of the cured film was evaluated based on the number of grids without peeling per 100 grids. It is practical at 50/100 or more.

(3) Scratch hardness (pencil method)
In accordance with JIS K5600-5-4, the scratch hardness was evaluated by the pencil hardness at which the cured film on the metal plate was coherently broken (scratched or broken when the cured film was removed) using a pencil. It can be evaluated that the scratch hardness of 3H or more is practical.

(4) Hairline polishing treatment A non-woven pad having a particle size of 320 (manufactured by Sumitomo 3M, trade name “Scotch Bright # 320”) was placed on the surface of the resin-coated metal plate, pressure 80 g / cm ² , moving speed 10 m / By operating at min and a feed pitch of 25 mm, a dry hairline polishing treatment was performed. The resin-coated metal plate after the hairline polishing treatment was immersed in a 4.0 mass% sodium hydroxide aqueous solution at 60 ° C. for 12 hours to peel the cured film. The surface of the metal plate was visually observed and evaluated for adaptability to the hairline polishing treatment according to the following criteria.
○: Scratches and dents due to polishing were not observed.
X: Scratches or dents due to polishing were observed.

(5) Vibration polishing treatment The resin-coated metal plate 10 was subjected to vibration polishing treatment. The vibration polishing process includes a main shaft 40, a motor 44 attached so that the rotating shaft 42 is eccentric with respect to the main shaft 40, a disc-shaped sponge 46 attached to the motor 44, and a surface of the sponge 46. This was performed using a vibration polishing apparatus 50 (see FIG. 4) provided with a disk-shaped nonwoven fabric pad 48 attached. In FIG. 4, the code | symbol 2 shows a metal plate and the code | symbol 4 shows a resin film. As the nonwoven fabric pad 48, a trade name “Scotch Bright # 180” (grain size 180) manufactured by Sumitomo 3M Co. was used.

The vibration polishing treatment was performed ^{twice with} a pressure of 20 g / cm ² , a spindle rotation speed of 1000 rpm, a spindle movement speed of 10 m / min, and a feed pitch of 50 mm. The resin-coated metal plate after the vibration polishing treatment was immersed in a 4.0 mass% sodium hydroxide aqueous solution at 60 ° C. for 12 hours to peel the cured film. The surface of the metal plate was visually observed, and the adaptability to the vibration polishing treatment was evaluated according to the following criteria.
○: Scratches and dents due to polishing were not observed.
X: Scratches or dents due to polishing were observed.

(6) Shot blast treatment A resin-coated metal plate is placed on a belt conveyor that operates at a moving speed of 0.5 m / min, and shot material (with an average particle size of 300 to 400 μm is used from above at a blade rotation speed of 4500 rpm. A blast shot process of spraying glass beads (# 46, manufactured by Toshiba Barotini Co., Ltd.) for 18 seconds was performed by an impeller method. The resin-coated metal plate after the shot blasting treatment was immersed in a 4.0 mass% sodium hydroxide aqueous solution at 60 ° C. for 12 hours to peel the cured film. The surface of the metal plate was visually observed and evaluated for adaptability to shot blasting according to the following criteria.
○: Scratches and dents due to shot blast were not observed.
X: Scratches or dents due to shot blasting were observed.

[Examples 2 to 18]
An ink composition was obtained in the same manner as in Example 1 using the monomers and photopolymerization initiator as shown in Table 1. Using the obtained ink composition, a resin-coated metal plate was prepared in the same manner as in Example 1. The film thickness of the formed cured film was adjusted by appropriately changing the type of inkjet head, the number of times of printing, and the resolution. And each resin-coated metal plate was evaluated. The results are shown in Tables 1 and 2.

[Comparative Examples 1-4]
An ink composition was obtained in the same manner as in Example 1 using the monomers and photopolymerization initiator as shown in Table 3. Using the obtained ink composition, a resin-coated metal plate was prepared and evaluated in the same manner as in Example 1. The results are shown in Table 3. Since the viscosity of the ink composition obtained in Comparative Example 2 was too high, the ink composition could not be discharged from the inkjet head, and a cured film could not be formed. For this reason, various evaluations could not be performed for Comparative Example 2.

  From the results shown in Tables 1 and 2, the cured films (resin films) of the resin-coated metal plates of Examples 1 to 18 have good cross-cut adhesion with the metal plates and have high scratch hardness (pencil method). Is clear. Moreover, if the resin-coated metal plate of Examples 1-18 is used, it turns out that it can surface-process only the desired processed surface, without damaging the surface of the metal plate coat | covered with the resin film.

  On the other hand, as shown in Table 3, the resin-coated metal plates of Comparative Examples 1, 3, and 4 were all scratched on the surface of the metal plate coated with the resin film. Thereby, it turns out that the resin-coated metal plates of Comparative Examples 1, 3 and 4 are not suitable as resin-coated metal plates for surface processing.

[Reference experiment]
As a reference experiment, the relationship between the type of UV source, the integrated light quantity of the irradiated UV light, and the yield stress of the formed resin film was examined.

  The ink composition prepared in Example 6 was discharged onto the surface of SUS304 BA having a thickness of 0.5 mm by an inkjet method to form a coating film having a thickness of 38 μm. A UV irradiation device 20 (see FIG. 2) equipped with a gallium metal halide lamp (120 W / cm) or a high-pressure mercury lamp (120 W / cm) as a UV lamp 12 (UV source) irradiates the coating film 24 with UV light 18. The coating film 24 was cured to obtain a resin film. The integrated light quantity was adjusted by irradiating UV light repeatedly with the speed of the conveyor 30 being 5 m / min. The integrated light amount was measured using an ultraviolet illuminometer / light meter (trade name: UV351-42, manufactured by Oak Manufacturing Co., Ltd.) having a measurement wavelength region of 340 to 490 nm and a wavelength center of 420 nm.

  About the formed resin film, the contact pressure-strain curve was created according to the measurement method of “(1) Yield stress of resin film (cured film)” described above, and the yield pressure was calculated. FIG. 1 is a graph showing a contact pressure-strain curve.

  As shown in FIG. 1, according to the contact pressure-strain curve ((1) to (4)) of the resin film cured using a gallium metal halide lamp as the UV source, the yield stress increases as the integrated light quantity increases. It can be seen that the number is also increasing. On the other hand, according to the contact pressure-strain curve ((5)) of the resin film cured using a high pressure mercury lamp as the UV source, the yield stress does not reach the desired 20 MPa or more, and elasticity No pressure increase due to deformation was observed. From the above, it is clear that it is effective to use a gallium metal halide lamp that emits intense light at 400 to 430 nm as an active energy ray source for irradiating the ink composition.

  By using the resin-coated metal plate of the present invention, a metal decorative plate having high definition and excellent design can be easily produced.

2 Metal plate 4, 14 Resin coating 10 Resin coated metal plate 12 UV lamp 16 Reflector 18 UV light 20 UV irradiation device 24 Coating film 30 Conveyor 32 Spherical indenter 40 Spindle 42 Rotating shaft 44 Motor 46 Sponge 48 Nonwoven pad 50 Vibration polishing device

Claims (5)

A metal plate and a resin film made of a cured product of an ink composition that covers a part of the surface of the metal plate;
The ink composition contains a polymerizable monomer that can be polymerized by active energy rays and a photopolymerization initiator, and has a viscosity at 25 ° C. of 3 to 50 mPa · s,
0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass is in the molecule. A monofunctional monomer having one ethylenic double bond group and no phosphate ester group;
The photopolymerization initiator comprises an acyl phosphine oxide-based initiator and an α-hydroxyketone-based initiator having one or less phenyl groups in the skeleton,
The resin film has a thickness of 5 to 80 μm, and the yield stress of the resin film is 20 MPa or more.
Resin-coated metal plate for surface processing. The resin-coated metal sheet for surface processing according to claim 1, wherein the polymerizable phosphate compound is a compound represented by any one of the following general formulas (A1) to (A4).

[Wherein, R represents a hydrogen atom or a methyl group, and R ₁ represents an alkylene group having 1 to 4 carbon atoms]

[Wherein, R and R ₁ are defined as in the general formula (A1), respectively]

[Wherein, R and R ₁ are each defined in the same manner as in the general formula (A1), and R ₂ represents an alkylene group having 1 to 10 carbon atoms]

[Wherein, R, R ₁ and R ₂ are defined in the same manner as in the general formula (A3)] Wherein 10-75 wt% of the polymerizable monomers have two or more ethylenic double bond group in the molecule, a polyfunctional monomer having no phosphoric acid ester group, according to claim 1 or The resin-coated metal plate for surface processing according to claim 2 . Patterning and applying the ink composition to the metal plate by an inkjet method;
A step of curing the patterned coating material of the ink composition by irradiation with active energy rays from a metal halide lamp doped with gallium to form a resin film having a thickness of 5 to 80 μm and a yield stress of 20 MPa or more. When,
Only including,
The ink composition contains a polymerizable monomer that can be polymerized by the active energy ray, and a photopolymerization initiator, and has a viscosity at 25 ° C. of 3 to 50 mPa · s,
0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass is in the molecule. It has one ethylenic double bond group, Ri monofunctional monomer der that do not have a phosphorus acid ester group,
The photopolymerization initiator is composed of an acyl phosphine oxide-based initiator and an α-hydroxyketone-based initiator having one or less phenyl groups in the skeleton.
A method for producing a resin-coated metal sheet for surface processing . Surface processing resin comprising a metal plate and a resin film having a thickness of 5 to 80 μm and a yield stress of 20 MPa or more, comprising a cured product of an ink composition covering a part of the surface of the metal plate Mechanical polishing and / or blasting the surface of the metal plate that is not coated with the resin film of the coated metal plate;
Removing the resin film from the metal plate;
Only including,
The ink composition contains a polymerizable monomer that can be polymerized by active energy rays and a photopolymerization initiator, and has a viscosity at 25 ° C. of 3 to 50 mPa · s,
0.5 to 13% by mass of the polymerizable monomer is a polymerizable phosphate compound having a phosphate group and an ethylenic double bond group in the molecule, and 10 to 75% by mass is a molecule. A monofunctional monomer having one ethylenic double bond group therein and no phosphate ester group,
A method for producing a metal decorative board.

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