WO2016136099A1

WO2016136099A1 - Resin-coated metal plate, method for producing resin-coated metal plate, and metal container

Info

Publication number: WO2016136099A1
Application number: PCT/JP2015/085028
Authority: WO
Inventors: 安秀大島; 北川　淳一; 克己小島; 中村　紀彦; 裕樹中丸
Original assignee: Ｊｆｅスチール株式会社
Priority date: 2015-02-27
Filing date: 2015-12-15
Publication date: 2016-09-01
Also published as: JPWO2016136099A1

Abstract

This resin-coated metal plate is provided with a resin coating layer on both surfaces of a metal plate, and is characterized in that a resin coating layer, which is positioned on the outer surface side of a container after shaping, is formed of a resin material that has an ethylene terephthalate unit of 97 mol% or more and contains a wax component within the range of from 0.05 PHR to 5 PHR (inclusive), while having a difference between the crystallization enthalpy and the melting enthalpy within the range of from 1 J/g to 20 J/g (inclusive) per unit weight after being provided on the metal plate.

Description

Resin-coated metal plate, method for producing resin-coated metal plate, and metal container

The present invention relates to a resin-coated metal plate provided with a resin film layer on both surfaces of the metal plate, a method for producing the resin-coated metal plate, and a metal container.

Generally, metal containers are roughly divided into 2-piece cans and 3-piece cans. A two-piece can is a metal container composed of two parts, a can body integrated with a can bottom and a lid. A three-piece can is a metal container composed of three parts: a can body, an upper lid, and a bottom lid. A two-piece can body has a beautiful appearance because it does not have a seam portion (welded portion), but is manufactured by a drawing method or the like, and therefore generally requires a high degree of processing. In contrast, the can body of the three-piece can has a seam portion, so that the appearance is inferior to that of the two-piece can body, but a high degree of processing is not necessary. In the processing of two-piece cans, the degree of processing increases as the capacity of the metal container increases, so generally two-piece cans are used for small-capacity metal containers and three-piece for large-capacity metal containers. Cans tend to be used.

As a material for two-piece cans, a technology has been proposed in which a can body is manufactured by a drawing method or DI (Draw & Ironing) processing method using a resin-coated metal plate having a resin coating layer on both sides of the metal plate. (See Patent Documents 1 to 3). In addition, in order to enhance the design of the can body formed with such a resin-coated metal plate, a technique of adding a white pigment to the resin film layer located on the outer surface side of the metal container after the molding process so that printing processing and the like are possible Has also been proposed (see Patent Documents 4 and 5). However, these are limited to applications such as food cans with a relatively low degree of processing, and among the two-piece cans, the can size is large and the drawing processing degree is high, such as an aerosol can, and the height of the can In the molding of a two-piece can having a high degree of stretching in the direction, that is, a two-piece can having a high degree of processing, it is difficult to apply defects such as molding scratches and irregularities in the coated resin. Especially for cans molded with a metal plate coated with a resin with a white pigment added to improve design, appearance defects tend to occur and the design is greatly reduced, so it cannot be used for high processing applications. It was. As such a two-piece can material having a high degree of processing, a technique has been proposed in which appearance defects due to heat treatment after molding are suppressed by controlling the crystallinity of the resin coating layer (see Patent Document 6).

Japanese Examined Patent Publication No. 7-106394 Japanese Patent No. 2526725 JP 2004-148324 A Japanese Patent Laid-Open No. 8-169098 JP 2004-130536 A International Publication No. 2013/030972

The inventors of the present invention use a resin-coated metal plate to form a two-piece can body having a high degree of processing, the adhesion between the processed resin film layer and the metal plate, and the inner surface of the metal container after the forming process. As a result of heat treatment for the purpose of improving the covering property of the resin coating layer located on the side and the design property of the resin coating layer on the outer surface side of the metal container after the molding process, forming into the resin coating layer on the surface side It has been found that defects in appearance due to scratches and micro unevenness occur. For this reason, in order to manufacture a two-piece can body having a high degree of processing using a resin-coated metal plate, it is necessary to prevent appearance defects from being caused by molding and heat treatment.

The present invention has been made in view of the above, and an object of the present invention is to provide a resin-coated metal plate, a method for producing a resin-coated metal plate, and a metal that can suppress appearance defects due to molding and heat treatment. To provide a container.

The inventors of the present invention have intensively studied, and as a result, have found that molding flaws are caused by insufficient slidability between the tool and the resin coating layer during molding. In addition, defects in appearance caused by heat treatment are caused by the residual stress in the resin coating layer generated during the molding process being relaxed by the heat treatment, causing the resin coating layer to deform non-uniformly, resulting in non-uniform pigment formation. It was found that this occurs because the distribution is formed. As a result of further research based on this finding, the inventors of the present invention have suppressed molding flaws by adding wax to the resin coating layer, and the micro unevenness after heat treatment has a specific resin composition. The inventors have come up with a technical idea that the resin film layer can be controlled by reducing the residual stress of the resin film layer after molding by controlling the crystallinity of the resin film layer.

The resin-coated metal plate according to the present invention is a resin-coated metal plate provided with a resin film layer on both surfaces of the metal plate, and the resin film layer located on the outer surface side of the container after molding processing has an ethylene terephthalate unit of 97 mol% or more. 1J in terms of the difference between the amount of heat of crystallization and the amount of heat of fusion after being coated on a metal plate, containing a wax component in the range of 0.05 PHR to 5 PHR, based on resin. / G or more and 20 J / g or less.

It is preferable that the resin coating layer located on the outer surface side of the container after the molding process contains 5 PHR or more and 30 PHR or less of titanium oxide.

The resin coating layer located on the outer surface side of the container after molding has a structure of two or more layers, and the resin coating layers of each layer are mainly composed of a resin having an ethylene terephthalate unit of 97 mol% or more, and from 1 μm to 5 μm from the outermost surface. It has a layer containing the following wax components, and the amount of wax relative to the amount of resin in the layer containing wax and the amount of wax relative to the resin amount of the entire resin coating layer are both in the range of 0.05 PHR to 5 PHR. The difference between the heat of crystallization and the heat of fusion of the resin film layer after being coated on the metal plate is preferably in the range of 1 J / g or more and 20 J / g or less in terms of unit weight.

The resin coating layer located on the outer surface side of the container after molding has a structure of two or more layers, and the resin coating layers of each layer are mainly composed of a resin having an ethylene terephthalate unit of 97 mol% or more, and from 1 μm to 5 μm from the outermost surface. It has a layer containing the following wax components, and the amount of wax relative to the amount of resin in the outermost surface layer containing wax and the amount of wax relative to the amount of resin in the entire resin coating layer are both in the range of 0.05 PHR to 5 PHR. The amount of titanium oxide with respect to the resin amount of the entire resin coating layer is in the range of 5 PHR to 30 PHR, and at least at a depth of 1 μm from the outermost surface, the amount of titanium oxide is in the range of 2 PHR or less, The difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the plate is in the range of 1 J / g or more and 20 J / g or less in terms of unit weight. It is preferred that in.

The resin coating layer located on the outer surface side of the container after molding has a structure of three or more layers consisting of an outermost surface layer, at least one intermediate layer, and the lowermost layer, and each resin coating layer is 97 mol of ethylene terephthalate unit. % Of the resin as a main component and a layer containing a wax component of 1 μm or more and 5 μm or less from the outermost surface and the lowermost surface, respectively, and the amount of wax relative to the amount of resin in the layer containing wax and the entire resin coating layer The amount of wax relative to the amount of resin is in the range of 0.05 PHR to 5 PHR, and the difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the metal plate is 1J in terms of unit weight. / G or more and 20 J / g or less is preferable.

The amount of titanium oxide with respect to the resin amount of the entire resin coating layer is in the range of 5 PHR to 30 PHR, and the amount of titanium oxide in the range of at least 1 μm from the outermost surface and 1 μm from the lowermost surface is 2 PHR or less. It is preferable to be within.

The difference between the amount of heat of crystallization and the amount of heat of fusion after the resin coating layer located on the inner surface side of the container after molding is coated on the metal plate is in the range of 1 J / g or more and 20 J / g or less in terms of unit weight. It is preferable that it is formed of the resin material inside.

It is preferable that the resin coating layer located on the inner surface side of the container after the molding process is formed of a resin material having an ethylene terephthalate unit of 97 mol% or more.

It is preferable that the contact angle with water of the resin coating layer located on the outer surface side of the container after the molding process is in the range of 82 ° to 100 ° after the molding process.

In the method for producing a resin-coated metal plate according to the present invention, a biaxially stretched film is used to form a resin-coated layer, and the film is heat-sealed on both sides of a metal plate heated to the melting point of the resin or higher. It is characterized by. It is more preferable that the heating temperature of the metal plate is (melting point of resin + 50 ° C.) or less.

The metal container according to the present invention is a metal container formed by molding the resin-coated metal plate according to the present invention, and the contact angle with water of the resin film layer located on the outer surface side of the metal container is 82. It is in the range of not less than 100 ° and not more than 100 °.

According to the resin-coated metal plate, the method for producing a resin-coated metal plate, and the metal container according to the present invention, the molding flaw and the residual stress of the resin film layer located on the outer surface side of the container can be reduced after the molding process. It is possible to suppress appearance defects from occurring due to the heat treatment.

FIG. 1 is a cross-sectional view showing a configuration of a resin-coated metal plate according to an embodiment of the present invention.

Hereinafter, a resin-coated metal plate according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view showing a configuration of a resin-coated metal plate according to an embodiment of the present invention. As shown in FIG. 1, a resin coated metal plate 1 according to an embodiment of the present invention includes a metal plate 2, a resin coated layer 3 formed on one surface side of the metal plate 2, and the other of the metal plate 2. And a resin coating layer 4 formed on the surface side. The resin coating layer 3 and the resin coating layer 4 are respectively positioned on the outer surface side and the inner surface side of the metal container after the molding process.

The metal plate 2 is formed of a steel plate such as tinplate or tin-free steel. As the tinplate, one having a tin plating amount of 0.5 to 15 g / m ² is preferably used. Tin-free steel, a metal layer of chromium coating weight 50 ~ 200 mg / ^{m 2,} may deposition amount of chromium metal converted to its upper layer and a 3-chromium oxide layer of 30 mg / ^{m 2.} The type of steel plate is not particularly limited as long as it can be formed into a desired shape, but the following components and manufacturing methods are preferable.

(1) Recrystallized annealed by box annealing using low carbon steel with C (carbon) content of about 0.01-0.10%.
(2) A low-carbon steel having a C content of about 0.01 to 0.10% and recrystallized by continuous annealing.
(3) Low carbon steel with a C content of about 0.01 to 0.10%, recrystallized and overaged by continuous annealing.
(4) A low carbon steel having a C content of about 0.01 to 0.10%, which is subjected to secondary cold rolling (DR (Double Reduced) rolling) after recrystallization annealing by box annealing or continuous annealing.
(5) Recrystallization annealing by continuous annealing using IF (Interstitial Free) steel to which elements that fix solute C such as Nb and Ti are added to ultra low carbon steel with C content of about 0.003% or less What you did.

The mechanical properties of the steel sheet are not particularly limited as long as they can be formed into a desired shape, but the yield strength YP is about 220 MPa or more and 580 MPa or less in order to maintain sufficient can body strength without impairing workability. It is desirable to use one. It is desirable that Rankford (r value), which is an index of plastic anisotropy, is 0.8 or more, and the in-plane anisotropy Δr of r value has an absolute value of 0.7 or less. desirable. The plate thickness of the steel plate can be set as appropriate from the shape of the target can and the required strength of the can. From the viewpoint of suppressing an increase in the cost of the steel sheet itself and the can body, it is desirable to use a sheet having a thickness of about 0.15 to 0.4 mm.

In addition, although the component of steel for achieving said characteristic is not specifically limited, For example, what is necessary is just to contain components, such as Si, Mn, P, S, Al, N, and the content of Si is Within 0.001 to 0.1%, Mn content within 0.01 to 0.6%, P content within 0.002 to 0.05%, S content Is in the range of 0.002 to 0.05%, the Al content is in the range of 0.005 to 0.100%, and the N content is in the range of 0.0005 to 0.020%. preferable. Moreover, although other components, such as B, Cu, Ni, Cr, Mo, and V, may be contained, the content of these other components is 0.02% or less in total from the viewpoint of ensuring corrosion resistance and the like. It is desirable to be.

The resin coating layer 3 is formed of a resin material having an ethylene terephthalate unit of 97 mol% or more, preferably 98 mol% or more. When the ethylene terephthalate unit is less than 97 mol%, the resin is softened by heat generated by sliding with the tool during molding, so that molding flaws are likely to occur and surface irregularities after heat treatment are likely to occur. The resin coating layer 3 may be a single layer or a structure of two or more layers, but the resin in each layer is such that the ethylene terephthalate unit is 97 mol% or more.

Since the resin coating layer 4 is bonded to both surfaces of the resin coating layer 3 and the metal plate 2, it is easy to manufacture when melted at a temperature close to the resin of the resin coating layer 3, and therefore the melting point equivalent to the resin of the resin coating layer 3 It is preferable that the ethylene terephthalate unit is 97 mol% or more. The resin coating layer 4 may also be a single layer or a structure having two or more layers, but the resin in each layer preferably has 97 mol% or more of ethylene terephthalate units.

The resin in the resin coating layers 3 and 4 may be copolymerized with other dicarboxylic acid components and glycol components as long as the heat resistance and workability are not impaired. Here, in the case of the resin coating layer 3, it shall be in the range of less than 3 mol% in resin. Moreover, also in the case of the resin film layer 4, it is preferable to set it in the range of less than 3 mol% in resin. Examples of the dicarboxylic acid component include isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenoxyethanedicarboxylic acid, 5-sodium sulfoisophthalic acid, aromatic dicarboxylic acid such as phthalic acid, oxalic acid, succinic acid, Examples thereof include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, dimer acid, maleic acid and fumaric acid, alicyclic carboxylic acids such as cyclohexanedicarboxylic acid, and oxycarboxylic acids such as p-oxybenzoic acid. Examples of glycol components include aliphatic glycols such as propanediol, butanediol, pentanediol, hexanediol, and neopentylglycol, alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bisphenol A and bisphenol S, and diethylene glycol. It can be illustrated. These dicarboxylic acid components and glycol components may be used in combination of two or more.

The resin material for forming the resin coating layers 3 and 4 is not limited by the manufacturing method. For example, (1) a method in which terephthalic acid, ethylene glycol, and a copolymer component are esterified and then a reaction product obtained is subjected to a polycondensation reaction to form a copolymer polyester, or (2) dimethyl terephthalate, ethylene glycol, A resin material can be formed by utilizing a method in which a copolymer component is subjected to a transesterification reaction and then a reaction product obtained is subjected to a polycondensation reaction to obtain a copolymer polyester. Further, another resin such as ethylene terephthalate resin and butylene terephthalate resin may be mixed to form a resin material. In the production of the copolyester, additives such as a fluorescent brightener, an antioxidant, a heat stabilizer, an ultraviolet absorber, and an antistatic agent may be added as necessary. Addition of a fluorescent brightening agent is effective for improving the whiteness. It is preferable to use a biaxially stretched film produced by melt-extruding a resin having such a composition from a T-die and forming it into a thin film and then stretching it in the longitudinal and transverse directions.

It is desirable that the time during which the resin coating layers 3 and 4 are heated to the melting point or higher when coating the metal plate 2 is in the range of 1 to 30 msec. The pressurizing pressure at the time of coating is not particularly limited, but the surface pressure is preferably in the range of 9.8 to 294 N (1 to 30 kgf / cm ² ). When the surface pressure is smaller than this range, even if the temperature at the interface between the metal plate 2 and the resin coating layers 3 and 4 is equal to or higher than the melting point, the time for which the temperature is equal to or higher than the melting point is short, the resin coating layer The melting of 3 and 4 becomes insufficient, and sufficient adhesion between the resin coating layers 3 and 4 and the metal plate 2 may not be obtained. On the other hand, when the surface pressure is larger than this range, the resin coating layers 3 and 4 may melt and adhere to the roll.

The resin coating layer 3 on the outer surface side of the container has a difference between the heat of crystallization and the heat of fusion after coating on the metal plate 2 of 1 J / g or more and 20 J / g or less, preferably 1 J / g in terms of unit weight. g or more and 15 J / g or less, more preferably 3 J / g or more and 10 J / g or less. The heat of crystallization and the heat of fusion can be measured using a differential scanning calorimeter (Differential Scanning Calorimetry: DSC). The difference between the heat of crystallization and the heat of fusion serves as an index of the crystallinity of the resin coating layer 3 after coating. When the difference between the amount of heat of crystallization and the amount of heat of fusion of the resin coating layer 3 is less than 1 J / g, the residual stress after molding is reduced, but the impact resistance is reduced, and when a certain level of impact is applied, Resin film cracking occurs. On the other hand, if the difference between the amount of heat of crystallization and the amount of heat of fusion is greater than 20 J / g, the degree of crystallinity of the resin coating layer 3 is increased, and the residual stress after molding is increased. Will occur. From the above, the difference between the heat of crystallization and the heat of fusion of the resin coating layer 3 on the outer surface side of the container is 1 J / g or more and 20 J / g or less.

The resin coating layer 4 on the inner surface side of the container has a difference between the heat of crystallization and the heat of fusion after being coated on the metal plate 2 in the range of 1 J / g or more and 20 J / g or less in terms of unit weight. It is desirable that it be formed of a resin material. When the difference between the amount of heat of crystallization and the amount of heat of fusion is less than 1 J / g, the impact resistance after the molding process decreases, and when an impact of a certain level or more is applied, a resin film crack may occur. On the other hand, when the difference between the heat of crystallization and the heat of fusion is greater than 20 J / g, the degree of crystallinity of the resin coating layer 4 increases, and the residual stress after molding increases. For this reason, corrosion resistance may deteriorate due to the occurrence of cracks in the resin coating layer 4.

The degree of crystallinity of the resin coating layers 3 and 4 is the orientation degree and melting point of the resin coating layers 3 and 4 before coating, and coating conditions (steel plate heating temperature, surface pressure during coating, time to cooling after coating, after coating Can be controlled by adjusting the cooling temperature and the line speed. For example, the crystallinity of the resin coating layers 3 and 4 can be lowered by increasing the heating temperature of the metal plate 2 during coating. The heating temperature of the metal plate 2 is higher than the melting point of the resin coating layers 3 and 4, but is preferably about 10 to 50 ° C. Moreover, the crystallinity degree of the resin film layers 3 and 4 can be made low by reducing a surface pressure and making the cooling effect of the resin film layers 3 and 4 by the pressurization at the time of covering small. In addition, the crystallization degree of the resin coating layers 3 and 4 is reduced by shortening the time until the cooling starts after coating and suppressing the crystallization of the resin coating layers 3 and 4 in the cooling process after coating. Can do. The time until the start of cooling after coating is in the range of 0.5 to 10 seconds, depending on the length of the line and the line speed. Further, by increasing the line speed, the crystallinity of the resin coating layers 3 and 4 can be lowered even under the same heating temperature. This is because the influence of cooling or the like from heating to coating is reduced.

The melting point of the resin coating layer 3 is in the range of 250 ° C. or more and 265 ° C. or less. When the resin coating layer 3 has a structure of two or more layers, the melting point difference between the layers is preferably 10 ° C. or less. More preferably, it is 6 ° C. or less, and further preferably 3 ° C. or less. When the melting point of the resin coating layer 3 is less than 250 ° C., the resin coating layer 3 is easily softened due to surface sliding during processing, processing heat generated by the metal plate 2, etc., and molding scratches are generated on the surface of the resin coating layer 3. Or may lead to resin breakage. On the other hand, when the melting point of the resin coating layer 3 is higher than 265 ° C., the crystallinity of the resin coating layer 3 is high, and there is a possibility that the processing with a high degree of processing cannot be followed. Further, when the difference in melting point of each layer is larger than 10 ° C., the melting state of each layer by heat treatment is greatly different, so that defects in appearance are likely to occur due to non-uniform displacement (flow).

The melting point of the resin coating layer 4 is also in the range of 250 ° C. or more and 265 ° C. or less from the viewpoint of bonding with the resin coating layer 3, and when the resin coating layer 4 has a structure of two or more layers, The melting point difference between the resin coating layer 3 and the resin is desirably 10 ° C. or less, more desirably 6 ° C. or less, and further desirably 3 ° C. or less. Further, when the melting point difference between each layer and the resin coating layer 3 is greater than 10 ° C., the melting state of each layer and the resin coating layer 3 due to the heat treatment is greatly different, so that defects are likely to occur due to non-uniform displacement (flow). Become.

A wax component is added to the resin coating layer 3 in order to suppress the occurrence of molding flaws in the resin coating layer 3 when a molding process with a high degree of processing is performed. The wax component to be added is not particularly limited, but an organic lubricant is preferable, and fatty acids such as stearic acid, stearic acid ester, palmitic acid, palmitic acid ester, fatty acid ester, paraffin, polyethylene, etc., which have good compatibility with the polyester resin. Although chain aliphatics can be used, it is particularly desirable to use carnauba wax having good compatibility with the polyester resin and a high melting point.

The amount of wax component added is in the range of 0.05 PHR to 5 PHR. When the added amount of the wax component is less than 0.05 PHR, the effect of lubrication is small, and the effect of suppressing appearance defects due to molding flaws cannot be obtained. On the other hand, when the added amount of the wax component is more than 5 PHR, there is a problem that the transfer of the wax component occurs when the resin coating layer 3 is wound in a roll shape, and the printability may be deteriorated. The amount of the wax component added is preferably in the range of 0.10 PHR to 3 PHR, more preferably in the range of 0.20 PHR to 2 PHR.

In the container molding process, when the resin coating layer 3 is subjected to a thermal history by molding processing or painting baking, the wax component tends to precipitate on the surface and the slidability tends to improve. If the added amount of the wax component is 0.05 PHR to 5 PHR, the position of the wax component in the thickness direction of the resin coating layer 3 is not limited, but it is added to the outermost surface layer of the resin coating layer 3. In this case, the outermost surface layer is preferably 1 μm or more and 5 μm or less from the outermost surface. The wax component of the outermost surface layer has a high effect of improving the slidability, and when added to the outermost surface layer, the effect of improving the slidability is enhanced even if the addition amount of the wax component is small. Moreover, it is preferable to add to the lowest layer of the resin film layer 3, and it is preferable that the lowest layer in that case is 1 micrometer or more and 5 micrometers or less from the lowest surface. The lowermost wax component has an effect of improving the resin adhesion at the time of molding by relaxing the stress generated at the interface between the resin layer and the metal plate during processing. When the film thickness of the outermost surface layer and the lowermost layer to which the wax component is added is smaller than 1 μm, the molding damage of the resin coating layer 3 may not be sufficiently suppressed or the resin adhesion during molding may be inferior. In some cases, the gloss of the surface of the resin coating layer 3 cannot be sufficiently secured. On the other hand, the film thickness of the outermost surface layer and the lowermost layer to which the wax component is added may be larger than 5 μm. However, since the improvement effect is further reduced, it is preferably 5 μm or less.

In the metal container formed by molding the resin-coated metal plate according to the present invention, the contact angle with water of the resin film layer 3 located on the outer surface side of the metal container is in the range of 82 ° to 100 °. Preferably, it is more preferably in the range of 85 ° to 95 °. Immediately after the production of the resin-coated metal plate, since the heating time is usually short, the wax component is often present in the initially added layer, but in the container molding process, the resin film layer 3 is When a thermal history is received by molding or painting baking, the wax component tends to precipitate on the surface and improve the slidability. In the metal container formed by molding the resin-coated metal plate according to the present invention by adding the wax component defined in the present invention, the resin film layer 3 located on the outer surface side of the metal container and the water The contact angle is in the range of 82 ° to 100 °, indicating that suitable molding has been performed. In addition, in order to estimate and evaluate the contact angle with water of the resin coating layer 3 after container molding before container molding, it is preferable to give a thermal history to the resin coating layer 3 and evaluate the contact angle with water after cooling. The conditions of the heat history are not particularly limited, but it is preferable to hold at a temperature of melting point −50 ° C. or higher and melting point + 30 ° C. or lower for 30 seconds or longer. For example, in the present invention, using a hot air drying furnace, the contact angle with water after heating to reach 240 ° C. in 90 seconds and forcibly cooling with cold air is a resin located on the outer surface side of the molded container It was confirmed that there was a good correlation with the contact angle of the coating layer 3 with water. The optimum contact angle range with water is 27 to 33 mN / m in terms of the optimum surface free energy range.

In order to prevent the resin coating layer 4 from being damaged, a wax component may be added to the resin in the same manner as the resin coating layer 3. In this case, the addition amount of the wax component is also preferably in the range of 0.05 PHR to 5 PHR.

The resin coating layer 3 may be required to be white so that a process for improving design properties such as a printing process is possible. Therefore, the resin coating layer 3 desirably contains titanium oxide within a range of 5 PHR to 30 PHR, preferably 10 PHR to 25 PHR, more preferably 12 PHR to 20 PHR. When the content of titanium oxide is less than 5 PHR, sufficient whiteness may not be ensured after processing. On the other hand, when the content of titanium oxide is more than 30 PHR, the adhesiveness and workability between the metal plate 2 and the resin coating layer 3 may become a problem when a forming process with a high workability is performed.

In order to ensure whiteness, it is preferable that the amount of titanium oxide with respect to the resin amount of the entire resin coating layer 3 is in the range of 5 PHR to 30 PHR, and the film thickness is 10 μm or more. Further, when the amount of titanium oxide in the vicinity of the outermost surface is high, it is easy to detach from the surface after molding. Therefore, the amount of titanium oxide at a position from the outermost surface of the resin coating layer 3 to at least 1 μm is preferably 2 PHR or less. . In addition, when the amount of titanium oxide in the vicinity of the lowermost surface is high, the adhesion with the base metal tends to be lowered. Therefore, the amount of titanium oxide in the range from the lowermost surface to at least 1 μm is more preferably 2 PHR or less.

The titanium oxide added to the resin coating layer 3 is not particularly limited, but it is preferable to use a rutile-type titanium oxide having a content of 90% or more. When the rutile type titanium oxide is lower than 90%, the dispersibility of the titanium oxide is not good when mixed with the resin material, and the molecular weight of the resin material may be lowered. In Examples and Comparative Examples of the present application, rutile type titanium oxide was used. As a method for adding titanium oxide, various methods as shown in the following (1) to (3) can be used. In addition, when adding titanium oxide using method (1), it is desirable to add titanium oxide to the reaction system as a slurry in which glycol is dispersed. In addition, the thickness of the resin coating layer 3 to which titanium oxide is added is desirably in the range of 10 to 40 μm, preferably 12 to 35 μm, more preferably 15 to 25 μm in order to ensure the whiteness after processing. . When the thickness of the resin coating layer 3 is less than 10 μm, the resin coating layer 3 is easily cracked during processing. On the other hand, when the thickness of the resin coating layer 3 is larger than 40 μm, the residual stress due to molding becomes too large and the adhesion may be inferior.

(1) Method of adding titanium oxide before transesterification or esterification reaction at the time of synthesis of copolymerized polyester or before the start of polycondensation reaction (2) Method of adding to copolymerized polyester and melt-kneading (3) Method In (1) and (2), a method for producing a master pellet to which a large amount of titanium oxide is added, kneading with a copolymerized polyester not containing particles, and containing a predetermined amount of titanium oxide

Also, in order to improve the adhesion between the titanium oxide and the film resin, it is preferable to treat the surface of the titanium oxide with silica, alumina or the like.

As described above, the resin coating layers 3 and 4 may be a single layer having the same composition or a multilayer structure. Further, the resin coating layers 3 and 4 are preferably in the range of 10 μm or more and 40 μm or less in the case of a single layer or multiple layers. If it is less than 10 μm, the resin coating layer 3 may be cracked during processing and the coverage may be inferior, and if it exceeds 40 μm, the residual stress due to molding becomes too large and the adhesion may be inferior. In addition, as long as the resin coating layers 3 and 4 have a predetermined configuration, the layer forming method is not limited. For example, a plurality of films having different components may be laminated, or a plurality of components may be formed on the film by a melt extrusion method. In addition, when forming a film by laminating a film having a plurality of components different from each other, the thickness of each layer is preferably 1 μm or more from the viewpoint of adhesion and the like. When forming a plurality of layers simultaneously by forming a layer or by melt extrusion, the thickness of each layer may be further reduced, and the layers may not be clearly separated.

Using T3CA (JIS G 3303) having a thickness of 0.23 mm, TFS (Tin Free Steel, metal Cr layer: 120 mg / m ² , Cr oxide layer: 10 mg / m ^{2 in} terms of metal Cr) as the metal plate, film heat The resin coating layers of Examples 1 to 38 and Comparative Examples 1 to 12 shown in Tables 1A and 1B below were formed on both surfaces of the metal plate using a pressure bonding method. Specifically, in a state where the metal plate is heated to a temperature 20 ° C. higher than the melting point of the resin coating layer, a film-like resin coating layer produced by a biaxial stretching method using a nip roll is thermocompression bonded to the metal plate, Subsequently, the resin film layer was coat | covered on both surfaces of the metal plate by cooling by water cooling within 5 second. In addition, on one surface side of the metal plate located on the outer surface side of the container after molding processing, a resin coating layer (outer surface resin layer) with and without titanium oxide is positioned on the inner surface side of the container after molding processing. The other surface side of the metal plate was coated with a resin coating layer (inner surface resin layer) not containing titanium oxide. Moreover, about the obtained resin film metal plate, melting | fusing point of the resin film layer, the crystallization heat amount of the resin film layer, and the heat of fusion of the resin film layer were measured using the method shown below. Moreover, about the outer surface resin layer, the contact angle with the whiteness and the water after heat processing was measured. The measurement results are shown in Tables 1A and 1B below.

(1) Melting point of resin coating layer When the temperature of the resin coating layer before coating is increased from room temperature to 290 ° C. at a rate of temperature increase of 10 ° C./min and a flow rate of nitrogen gas of 50 ml / min using a differential scanning calorimeter. The endothermic peak was measured, and the peak temperature of the endothermic peak measured between 200 and 280 ° C. was defined as the melting point of the resin coating layer.

(2) Heat of crystallization and heat of fusion The metal surface of the resin-coated metal plate was dissolved with diluted hydrochloric acid to peel off the resin coating layer, and the peeled resin coating layer was sufficiently washed with distilled water and dried. Hereafter, this method was used when it was necessary to evaluate the peeled resin coating layer. Then, using a differential scanning calorimeter, an exothermic peak and an endothermic peak are measured when the temperature of the resin coating layer is increased from −50 ° C. to 290 ° C. at a rate of temperature increase of 10 ° C./min and a flow rate of nitrogen gas of 50 ml / min. Then, the heat of crystallization was calculated from the area of the exothermic peak observed between 100 to 200 ° C., and the heat of fusion was calculated from the area of the endothermic peak observed between 200 ° C. and 280 ° C. For the outer surface resin layer, the amount of crystallization heat and the amount of heat of fusion per unit weight of the resin were calculated using the weight excluding the titanium oxide content as the amount of resin.

(3) Whiteness Using a spectral color difference meter, the whiteness of the resin coating layer 3 of the resin-coated metal plate was evaluated by the method shown in JIS Z 8722. The measurement area was 30 mmφ, the measurement light source was the C condition, and the L value of the Hunter Lab value measured under the observation condition of the 2 ° visual field with respect to the measurement light source was defined as whiteness. In addition, when L value is 75 or more, it is suitable as a white film.

(4) Contact angle with water after heat treatment Using a hot air drying furnace, the metal plate was heated in 90 seconds until the temperature reached 240 ° C. and forcedly cooled with cold air, and then contact angle meter (Kyowa Interface Science ( The static contact angle of water with respect to the resin coating layer 3 was measured using a CA-DT type).

[Evaluation]
The resin-coated metal plates described in Tables 1A and 1B were evaluated for formability, appearance, corrosion resistance, post-processing adhesion, and impact resistance using the methods described below. The evaluation results are shown in Table 2 below. As shown in Table 2, in the resin-coated metal plates of Examples 1 to 38, the moldability and appearance scores were “◎◎◎”, “◎◎”, “◎”, or “○”, In the resin-coated metal plates of Comparative Examples 1 to 11, the formability and appearance scores were “Δ” and “X”. Here, referring to Tables 1A and 1B, in the resin-coated metal plates of Examples 1 to 38, the outer surface resin layer has an ethylene terephthalate unit of 97 mol% or more and a wax component in the range of 0.05 PHR to 5 PHR. The difference between the amount of heat of crystallization and the amount of heat of fusion after being coated on the metal plate is formed of a resin material of 1 J / g or more and 20 J / g or less in terms of unit weight. In contrast, in the resin-coated metal plates of Comparative Examples 1 to 11, either the resin composition, the wax component, or the difference between the heat of crystallization and the heat of fusion of the outer surface resin layer is different. In the metal plate, the outer surface resin layer is formed of a resin material having a difference between the amount of heat of crystallization and the amount of heat of fusion of 0 J / g in terms of unit weight.

(1) Formability A 123 mm diameter disc was punched into the resin-coated metal plate described in Tables 1A and 1B, and a shallow drawn can was formed at a drawing ratio of 1.7. Next, redrawing and DI processing were performed on the shallow drawn can with a drawing ratio of 1.4 to form a deep drawn can. The deep drawn can thus obtained was heated in a hot air drying oven for 2 minutes until the can body temperature reached 250 ° C. in order to simulate the thermal history of subsequent printing and baking, and then cooled to cold air. Forced cooling. And the molding flaw on the surface of the resin film was visually observed after molding, and a score was given according to the following criteria.
Rating "◎◎◎": No film forming flaws are observed.
Rating “◎◎”: When a film molding flaw occurs at a height within 1 mm from the can flange.
Score “◎”: When a film molding flaw occurs at a height position within 3 mm exceeding 1 mm from the can flange portion.
Score “◯”: When a film forming defect occurs at a height position exceeding 3 mm and within 5 mm from the can flange portion.
Score “Δ”: When a film molding flaw occurs at a height position of more than 5 mm and within 10 mm from the can flange portion.
Score “X”: When a film molding flaw occurs up to a height position exceeding 10 mm from the can flange portion.

(2) Appearance A 158 mm diameter disc was punched into the resin-coated metal plate described in Tables 1A and 1B to obtain a shallow drawn can with a drawing ratio of 1.7. Next, the shallow drawn can was redrawn at a drawing ratio of 1.5 to form a deep drawn can. The deep drawn can thus obtained was heated in a hot air drying oven for 2 minutes until the can body temperature reached 250 ° C. in order to simulate the thermal history of subsequent printing and baking, and then cooled to cold air. Forced cooling. The state of the outer surface film after cooling was visually observed and scored according to the following criteria.
Rating "◎◎◎": When surface irregularities are not observed at all.
Score “◎◎”: When surface irregularities occur at a height within 1 mm from the can flange.
Score “◎”: When a surface irregularity defect occurs at a height position within 2 mm exceeding 1 mm from the can flange portion.
Score “◯”: When a surface irregularity defect occurs at a height of 3 mm or more exceeding 2 mm from the can flange portion.
Rating “Δ”: When a surface irregularity defect occurs at a height position within 3 mm exceeding 3 mm from the can flange portion.
Score “X”: When a surface irregularity defect occurs at a height position exceeding 5 mm from the can flange portion.

(3) Corrosion resistance The resin film layer of the can flange part of the deep drawn can which was molded and heat-treated in appearance evaluation was shaved to expose the metal plate. Thereafter, 5% saline solution is poured into the can, and the platinum electrode is immersed therein (the position where the immersion is performed is the center of the can), and the platinum electrode and the flange portion of the can (exposed portion of the steel plate) are used as a cathode and an anode, respectively. A voltage of 6 V was applied between the electrodes, and the current value after 4 seconds was read. And the average value of the electric current value after 10 cans measurement was calculated | required, and the score was attached according to the reference | standard shown below.
Rating “◎◎”: Current value less than 0.001 mA Rating “◎”: Current value 0.001 mA or more, less than 0.01 mA Rating “◯”: Current value 0.01 mA or more, less than 0.1 mA Rating “△”: Current Value 0.1 mA or more, less than 1.0 mA Rating “×”: Current value 1.0 mA or more

(4) Adhesiveness after processing A sample for peel test (width 15 mm × length 120 mm) was cut out from the can body of the deep-drawn can formed in the appearance evaluation. The resin film layer on the outer surface of the can is partly peeled off from the long side end of the cut sample, and the peeled resin film layer is opened in the direction opposite to the metal plate from which the resin film layer has been peeled (angle: 180 degrees). A peel test was conducted at a tensile speed of 30 mm / min, and the adhesion per 15 mm width was evaluated according to the following criteria.
Score “◎”: 3.0 N / 15 mm or more Score “◯”: 2.0 N / 15 mm or more, less than 3.0 N / 15 mm “Δ”: 1.0 N / 15 mm or more, less than 2.0 N / 15 mm “×” ": Less than 1.0N / 15mm

(5) Impact resistance A sample for impact test (width 80 mm x length 80 mm) was cut out from the can body of a deep-drawn can that was molded and heat-treated in appearance evaluation, and the outer surface side of the can became convex, and the tip A DuPont impact test with a radius of 6.35 mm, a load of 300 g, and a height of 100 mm was performed (based on JIS K 5600). Then, a sponge dipped in 5% saline was applied to the impact portion on the convex portion side (can outer surface side), and a platinum electrode was applied thereto. Using the platinum electrode and impact test sample end (steel plate exposed portion) as the cathode and anode, respectively, a voltage of 6.2 V was applied between the electrodes, the current value after 4 seconds was read, and the average value after 10 cans was measured.
Rating “◎”: Current value less than 0.05 mA Rating “◯”: Current value 0.05 mA or more, less than 0.5 mA Rating “Δ”: Current value 0.5 mA or more Rating less than 5 mA “X”: Current value 5 mA or more

Using T3CA (JIS G 3303) having a thickness of 0.23 mm, TFS (Tin Free Steel, metal Cr layer: 120 mg / m ² , Cr oxide layer: 10 mg / m ^{2 in} terms of metal Cr) as the metal plate, film heat Resin coating layers of Examples 101 to 141 and Comparative Examples 101 to 112 shown in Tables 3A to 3D below were formed on both surfaces of a metal plate by using a pressure bonding method. Specifically, two or three resin coating layers shown in Tables 3A to 3D are laminated as a film, and the metal plate is the melting point of the resin coating layer (if each layer has a different melting point, the melting point of the highest layer is used). ) In a state heated to a temperature higher by 20 ° C., a film-like resin coating layer produced by a biaxial stretching method using a nip roll is thermocompression bonded to a metal plate, and then cooled by water cooling within 5 seconds, The resin film layer was coat | covered on both surfaces of the metal plate. In addition, on one surface side of the metal plate located on the outer surface side of the container after molding processing, a resin coating layer (outer surface resin layer) with and without titanium oxide is positioned on the inner surface side of the container after molding processing. The other surface side of the metal plate was coated with a resin coating layer (inner surface resin layer) not containing titanium oxide. Moreover, about the obtained resin film metal plate, the melting | fusing point of the resin film layer, the crystallization heat amount of the resin film layer, and the heat of fusion of the resin film layer were measured using the same method as the above [Example 1]. Moreover, about the outer surface resin layer, the contact angle with the whiteness and the water after heat processing was measured. The measurement results are shown in Tables 3A to 3D below.

[Evaluation]
For the resin-coated metal plates described in Tables 3A to 3D, the formability, appearance, corrosion resistance, post-processing adhesion, and impact resistance were evaluated using the same methods as in [Example 1] above. The evaluation results are shown in Table 4 below. As shown in Table 4, in the resin-coated metal plates of Examples 101 to 141, the score of formability and appearance was “◎◎◎”, “◎◎”, “◎”, or “○”, In the resin-coated metal plates of Comparative Examples 101 to 110, 112, the formability and appearance scores were “◯”, “Δ”, and “X”. Here, referring to Tables 3A to 3D, in the resin-coated metal plates of Examples 101 to 141, the outer surface resin layer has a structure of two or more layers, and the film thickness of the outermost surface layer is 1 μm or more. Each of the resin coating layers is 97 mol% or more of ethylene terephthalate unit, the outermost surface layer contains a wax component in the range of 0.05 PHR or more and 5 PHR or less, and the amount of the wax component is based on the resin amount of the entire resin coating When converted, it is 0.05 PHR or more and 5 PHR or less, and the difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the metal plate is a range of 1 J / g or more and 20 J / g or less in terms of unit weight. It is formed by the resin material inside. In contrast, in the resin-coated metal plates of Comparative Examples 101 to 110, 112, either the resin composition, the wax component, or the difference between the heat of crystallization and the heat of fusion of the outer resin layer is different. In the resin-coated metal plate, the outer resin layer is formed of a resin material having a difference between the amount of crystallization heat and the heat of fusion converted to 0 J / g per unit weight.

Using T3CA (JIS G 3303) having a thickness of 0.23 mm, TFS (Tin Free Steel, metal Cr layer: 120 mg / m ² , Cr oxide layer: 10 mg / m ^{2 in} terms of metal Cr) as the metal plate, film heat The resin coating layers of Examples 201 to 237 and Comparative Examples 201 to 211 shown in Tables 5A to 5E below were formed on both surfaces of a metal plate by using a pressure bonding method. Specifically, the films are laminated in the configurations shown in Tables 5A to 5E, and the metal plate is heated to a temperature 20 ° C. higher than the melting point of the resin coating layer (if each layer has a different melting point, the melting point of the highest layer). In this state, a resin film layer formed on the both sides of the metal plate is obtained by thermocompression bonding the film-like resin film layer produced by the biaxial stretching method using a nip roll to a metal plate and then cooling with water cooling within 5 seconds. Was coated. In addition, on the surface side of the metal plate located on the outer surface side of the container after the molding process, a resin coating layer (outer surface resin layer) with or without titanium oxide, the metal plate positioned on the inner surface side of the container after the molding process A resin coating layer (inner surface resin layer) that does not contain titanium oxide was coated on the back surface side. Moreover, about the obtained resin film metal plate, melting | fusing point of a resin film layer, the crystallization calorie | heat amount of a resin film layer, and melting | fusing of a resin film layer using the same method as said [Example 1] and [Example 2]. The amount of heat was measured. Moreover, about the outer surface resin layer, the contact angle with the whiteness and the water after heat processing was measured. The measurement results are shown in Tables 5A to 5E below.

[Evaluation]
For the resin-coated metal plates described in Tables 5A to 5E, the moldability, appearance, corrosion resistance, post-processing adhesion, and impact resistance are obtained using the same methods as in [Example 1] and [Example 2]. Evaluated. The evaluation results are shown in Table 6 below. As shown in Table 6, in the resin-coated metal plates of Examples 201 to 237, the moldability and appearance scores were “◎◎◎”, “◎◎”, “◎”, or “○”, In the resin-coated metal plates of Comparative Examples 201 to 210, the scores of formability and appearance were “◎”, “◯”, “Δ”, and “×”. Here, referring to Tables 5A to 5E, in the resin-coated metal plates of Examples 201 to 237, the outer resin layer has a three-layer structure including an outermost surface layer, an intermediate layer, and a lowermost layer. Each of the coating layers has an ethylene terephthalate unit of 97 mol% or more, has a layer containing a wax component of 1 μm or more and 5 μm or less from the outermost surface and the lowermost surface, respectively, and the amount of wax relative to the amount of resin in the layer containing wax The amount of wax relative to the amount of resin in the entire resin coating layer is in the range of 0.05 PHR to 5 PHR, and the difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the metal plate is per unit weight. The resin material is in the range of 1 J / g or more and 20 J / g or less. In contrast, in the resin-coated metal plates of Comparative Examples 201 to 210, either the resin composition, the wax component, or the difference between the heat amount of crystallization and the heat of fusion of the outer surface resin layer is different, and the resin film of Comparative Example 211 is used. In the metal plate, the outer surface resin layer is formed of a resin material having a difference between the amount of heat of crystallization and the amount of heat of fusion of 0 J / g in terms of unit weight.

According to the present invention, it is possible to provide a resin-coated metal plate, a method for producing a resin-coated metal plate, and a metal container that can suppress appearance defects due to molding and heat treatment.

1 resin-coated metal plate 2 metal plate 3,4 resin-coated layer

Claims

A resin-coated metal plate provided with a resin film layer on both surfaces of the metal plate, the resin film layer located on the outer surface side of the container after the molding processing is mainly composed of a resin having an ethylene terephthalate unit of 97 mol% or more, and 0.05 PHR The wax component in the range of 5 PHR or less is contained, and the difference between the heat of crystallization and the heat of fusion after being coated on the metal plate is within the range of 1 J / g or more and 20 J / g or less in terms of unit weight. A resin-coated metal plate characterized by being.
2. The resin-coated metal sheet according to claim 1, wherein the resin coating layer located on the outer surface side of the container after molding processing contains 5 PHR or more and 30 PHR or less of titanium oxide.
The resin coating layer located on the outer surface side of the container after molding has a structure of two or more layers, and the resin coating layers of each layer are mainly composed of a resin having an ethylene terephthalate unit of 97 mol% or more, and from 1 μm to 5 μm from the outermost surface. It has a layer containing the following wax components, and the amount of wax relative to the amount of resin in the layer containing wax and the amount of wax relative to the resin amount of the entire resin coating layer are both in the range of 0.05 PHR to 5 PHR. The resin film layer after being coated on the metal plate is formed of a resin material in which the difference between the heat of crystallization and the heat of fusion is within a range of 1 J / g or more and 20 J / g or less in terms of unit weight. The resin-coated metal plate according to claim 1.
The resin coating layer located on the outer surface side of the container after molding has a structure of two or more layers, and the resin coating layers of each layer are mainly composed of a resin having an ethylene terephthalate unit of 97 mol% or more, and from 1 μm to 5 μm from the outermost surface. It has a layer containing the following wax components, and the amount of wax relative to the amount of resin in the outermost surface layer containing wax and the amount of wax relative to the amount of resin in the entire resin coating layer are both in the range of 0.05 PHR to 5 PHR. The amount of titanium oxide with respect to the resin amount of the entire resin coating layer is in the range of 5 PHR to 30 PHR, and at least at a depth of 1 μm from the outermost surface, the amount of titanium oxide is in the range of 2 PHR or less, The difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the plate is in the range of 1 J / g or more and 20 J / g or less in terms of unit weight. Of claims 1 to 3, characterized in that the resin coating the metal plate according to any one.
The resin coating layer located on the outer surface side of the container after molding has a structure of three or more layers consisting of an outermost surface layer, at least one intermediate layer, and the lowermost layer, and each resin coating layer is 97 mol of ethylene terephthalate unit. % Of the resin as a main component and a layer containing a wax component of 1 μm or more and 5 μm or less from the outermost surface and the lowermost surface, respectively, and the amount of wax relative to the amount of resin in the layer containing wax and the entire resin coating layer The amount of wax relative to the amount of resin is in the range of 0.05 PHR to 5 PHR, and the difference between the heat of crystallization and the heat of fusion of the resin coating layer after being coated on the metal plate is 1J in terms of unit weight. The resin-coated metal plate according to claim 1 or 3, wherein the resin-coated metal plate is in a range of not less than / g and not more than 20 J / g.
The amount of titanium oxide with respect to the resin amount of the entire resin coating layer is in the range of 5 PHR to 30 PHR, and the amount of titanium oxide in the range of at least 1 μm from the outermost surface and 1 μm from the lowermost surface is 2 PHR or less. 6. The resin-coated metal plate according to claim 1, wherein the resin-coated metal plate is in the interior.
The difference between the amount of heat of crystallization and the amount of heat of fusion after the resin coating layer located on the inner surface side of the container after molding is coated on the metal plate is in the range of 1 J / g or more and 20 J / g or less in terms of unit weight. The resin-coated metal plate according to any one of claims 1 to 6, wherein the resin-coated metal plate is formed of an internal resin material.
The resin coating layer located on the inner surface side of the container after the molding process is formed of a resin material having an ethylene terephthalate unit of 97 mol% or more, according to any one of claims 1 to 7. Resin coated metal plate.
9. The contact angle with water of the resin coating layer located on the outer surface side of the container after the molding process is in the range of 82 ° to 100 ° after the molding process. 2. The resin-coated metal plate according to item 1.
The method for producing a resin-coated metal plate according to any one of claims 1 to 9, wherein the biaxially stretched film is heat-sealed to both surfaces of the metal plate heated to the melting point of the resin or higher. A method for producing a resin-coated metal sheet.
A metal container formed by molding the resin-coated metal plate according to any one of claims 1 to 9, wherein the resin film layer located on the outer surface side of the metal container is in contact with water. A metal container having an angle in the range of 82 ° to 100 °.