JP2005349787A - Manufacturing method of resin coated metal sheet excellent in adhesion of resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing at a relatively low cost a polyolefin resin coated metal sheet having superior adhesion. <P>SOLUTION: The manufacturing method of the resin coated metal sheet comprises coating a composite resin 5 on a metal sheet 2. The method is characterized in that, of polyolefin resin layers 3, 4 which constitute the composite resin 5, the innermost polyolefin resin layer 3 which is located in contact with the metal sheet 2 is formed by extruding a molten maleic acid-modified polyolefin resin from a T die 6 on the metal sheet 2 having a temperature which is the temperature of the molten maleic acid-modified polyolefin resin or higher and 340°C or lower; that the metal sheet on which the composite resin 5 has been formed is pressed with a first roll 7 and a second roll 8 controlled to a temperature of ≥10°C and <50°C so that the outermost polyolefin resin layer 4 may contact the first roll 7; and that, even after the pressing, the contacting condition of the metal sheet 2 and the first roll 7 is maintained until the pressing position of the first roll 7 rotates in the range of less than one revolution. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a resin-coated metal plate which is constituted by lamination of a polyolefin resin and a metal plate and has excellent resin adhesion.

  Thermoplastic resins are not only used as film, sheet or molded container materials because they are easy to process, but are also widely used as laminates with various resin films, paper, metal foils and the like. Thermoplastic resins such as polyolefin and polyester are mainly used for these laminates, and a film laminating method in which a resin film is pressure-bonded to a heated base material, or a base material and a film are pressure-bonded while being heated, or heat-melted heat Generally, it is manufactured by an extrusion laminating method in which a plastic resin is directly laminated on a substrate. Among these, the extrusion laminating method is economical because it does not require the cost of film formation.

  A laminate in which a metal plate and a resin are laminated is widely used for building materials and containers. In particular, so-called laminated steel sheets obtained by laminating various steel sheets and thermoplastic resins are excellent in corrosion resistance, insulation, and the like, and therefore are widely used for building materials such as interior and exterior and cans.

  In these resin-coated metal plates such as laminated steel plates, adhesion between the metal plate and the resin is required, but generally satisfactory adhesion is hardly obtained even if a thermoplastic resin is thermally fused onto the metal plate. Therefore, some measure for obtaining good adhesion is required.

For example, Patent Document 1 discloses a method for manufacturing a surface-treated metal plate in which a molten resin is pressure-bonded by a heating roll and a cooling roll on a metal substrate preheated to 50 to 170 ° C. The preheating temperature is set to be equal to or lower than the temperature of the molten resin, preferably lower by 50 ° C. than the temperature of the molten resin. In Patent Document 2, a molten film of a thermoplastic resin and a metal substrate heated to Tm−80 ° C. to Tm + 50 ° C. (Tm is the melting point of the resin) are fused using a warm laminating roll. A method for producing a resin-metal laminate material that is then rapidly cooled is disclosed. However, neither of the methods of Patent Documents 1 and 2 has sufficient resin adhesion. Moreover, since the method of patent document 2 requires a quick cooling means, the space and cost which an apparatus occupies become large.
Japanese Patent Publication No. 3-41342 Japanese Patent No. 3470527

Further, Patent Documents 3 and 4 describe a method for producing a laminated metal plate (thermoplastic resin-coated metal plate) in which a molten thermoplastic resin flows down between a preheated metal plate and a roll to coat the resin on the metal plate. Both disclose that the preheating temperature of the metal plate is equal to or lower than the temperature of the molten resin. However, in any of these methods, since the preheating temperature of the metal substrate is too low, sufficient resin adhesion cannot be obtained. Moreover, since the cooling means is essential in the method of Patent Document 4, the space occupied by the apparatus and the cost increase.
JP-A-6-64019 JP-A-6-71777

Patent Document 5 discloses a method for manufacturing a thermoplastic resin-coated corrugated metal plate in which a molten thermoplastic resin flows down on a metal plate preheated to about 100 to 300 ° C. and pressed against the metal plate with a cooled crimping roll. Has been. In this case, the cooling temperature of the pressure-bonding roll is not specified, but as a guideline, the glass transition temperature or lower of the flowing thermoplastic resin is preferred. When this is applied to a polyolefin resin, the cooling temperature of the pressure-bonding roll is preferably about −80 ° C. or less for polyethylene and about −10 ° C. or less for polypropylene, and cannot be carried out by a simple method such as water cooling. Also, condensation occurs on the roll surface during operation, which hinders operation.
JP 2000-202943 A

Patent Document 6 discloses a method of manufacturing a laminated metal plate in which a molten thermoplastic resin film is flowed between a preheated metal plate wound around a cooling roll and a nip roll to cover the metal plate with the thermoplastic resin film. Is disclosed. However, in this method, since the metal plate is cooled by the cooling roll rather than the thermoplastic resin film constituting the laminated metal plate, sufficient resin adhesion cannot be obtained.
JP-A-4-299140

  An object of the present invention is to provide a method for producing a polyolefin resin-coated metal sheet having excellent adhesion at a relatively low cost.

  In the prior arts disclosed in Patent Documents 1 to 4 and 6, it is difficult to satisfy the resin adhesion. In addition, the prior arts disclosed in Patent Documents 2 and 4 have the disadvantage that the cost is relatively high. The prior art disclosed in Patent Document 5 has been difficult to apply to polyolefin resins.

  Accordingly, the inventors have intensively studied to solve the above problems in the resin-coated metal plate coated with a composite resin composed of a plurality of polyolefin resin layers. As a result, the maleic acid-modified polyolefin resin is obtained by a predetermined method using an extrusion laminating method. A pair of rolls including a temperature-controlled first roll (preferably a metal crimping roll) that is extruded onto a metal plate preheated to a temperature and is in contact with the composite resin. The inventors have newly found that it is effective for resin adhesion that the resin layer is brought into contact with the peripheral surface of the first roll, and the present invention has been completed.

That is, the gist configuration of the present invention is as follows.
(1) In the method for producing a resin-coated metal plate in which a metal plate is coated with a composite resin composed of a plurality of polyolefin resin layers,
Among the polyolefin resin layers constituting the composite resin, the innermost polyolefin resin layer positioned in contact with the metal plate is a temperature of the molten maleic acid-modified polyolefin resin in the molten state from the T die. Above, formed by extruding onto a metal plate at a temperature of 340 ° C or lower,
The outermost polyolefin resin constituting the uppermost layer of the composite resin with a pair of rolls composed of a first roll and a second roll in which the metal plate on which the composite resin is formed is controlled to a temperature of 10 ° C. or higher and lower than 50 ° C. The layer is pressure-bonded so as to be in contact with the first roll, and also after the pressure bonding, until the contact position between the metal plate and the first roll is rotated within a range of less than one rotation. A method for producing a resin-coated metal plate excellent in resin adhesion, characterized in that the method is maintained.

(2) The method for producing a resin-coated metal plate having excellent resin adhesion as described in (1) above, wherein the composite resin is coated on the metal plate by a coextrusion laminating method.

(3) The contact state between the metal plate after the crimping and the first roll is maintained until the crimping position of the first roll rotates by a quarter or more, (1) or (2) The manufacturing method of the resin-coated metal plate excellent in resin adhesion.

  According to the present invention, a polyolefin resin-coated metal plate having excellent resin adhesion can be produced at a relatively low cost.

Hereinafter, embodiments of the present invention will be described in detail.
This invention is a method for producing a resin-coated metal plate for coating a metal plate with a composite resin composed of a plurality of polyolefin resin layers. In such a method, the metal plate of the polyolefin resin layer constituting the composite resin is applied to the metal plate. The innermost polyolefin resin layer located in contact with each other and functioning as an adhesive layer is formed of a metal having a temperature of not less than 340 ° C. and not less than the temperature of the molten maleic acid-modified polyolefin resin from the T-die. It is formed by extruding onto a plate.

  The maleic acid-modified polyolefin resin has a carboxyl group in the molecule and therefore has excellent adhesion to metals and polar molecules. By using this maleic acid-modified polyolefin resin for the adhesive layer in contact with the metal plate, the composite resin can be formed with good adhesion to the metal plate. Furthermore, greater adhesion can be obtained by bringing the innermost polyolefin resin layer into contact with the metal plate in a molten state using an extrusion laminating method. In particular, the extrusion laminating method has an advantage that the manufacturing cost can be suppressed lower than the film laminating method because the film forming step is unnecessary.

  Here, the extrusion laminating method is a method of forming a thermoplastic resin film using a screw and a T-die. For example, a pellet-like thermoplastic resin is put into a cylinder containing a screw, and the resin is put into the cylinder. The mixture is fed into the T-die while being kneaded by rotating the screw while being heated and melted. The discharge die of the T die has a slit shape, and the molten resin becomes a film (film) shape by being extruded from the T die. The temperature of the maleic acid-modified polyolefin resin during extrusion is preferably 180 ° C. or higher from the viewpoint of ensuring fluidity. The upper limit of the temperature of the maleic acid-modified polyolefin resin during extrusion is not particularly limited, but is more preferably about 300 ° C. from the viewpoint of preventing thermal decomposition of the maleic acid-modified polyolefin resin.

  Further, in the present invention, in order to minimize the heating step of the metal plate and the maleic acid-modified polyolefin resin, to prevent thermal decomposition of the maleic acid-modified polyolefin resin, and to reduce the manufacturing cost, the maleic acid-modified polyolefin resin is used. In addition to this, a composite resin composed of the innermost polyolefin resin layer and one or more polyolefin resin layers including the outermost polyolefin resin layer needs to be coated on the metal plate in the same process.

  As a method for forming (covering) one or more polyolefin resin layers including the outermost polyolefin resin layer, any of an extrusion laminating method and a film laminating method may be used. However, more preferable is an extrusion laminating method, and in particular, a co-extrusion laminating method in which a plurality of layers of resin are extruded by a single T-die simultaneously coats a plurality of polyolefin resin layers containing the maleic acid-modified polyolefin resin on a metal plate. It is optimal because it can.

  The co-extrusion method using a T die includes a feed block method, a multi-manifold method, a dual slot method, and the like, and laminating the molten resin before the die, in the die, and after coming out of the die, Any method may be used.

  FIG. 1 schematically shows a production apparatus for carrying out a method for producing a resin-coated metal plate according to the present invention. Specifically, when a co-extrusion laminating method is used as a coating method for a composite resin. It is an example.

  A manufacturing apparatus 1 shown in FIG. 1 extrudes a molten maleic acid-modified polyolefin resin fed from a cylinder containing a screw (not shown) and another polyolefin resin in a molten state in the same process to form a metal plate. 2, a co-extrusion T die 6 for forming (coating) a composite resin 5 composed of the innermost polyolefin resin layer 3 and the outermost polyolefin resin 4 and a molten resin extruded by the T die 6 are pressure-bonded. It is mainly comprised by the rolls 7 and 8 which make the pair which consists of the roll 7 and the 2nd roll 8, and the heating apparatus 9 for heating the metal plate 2 which forms the composite resin 5 previously.

  The first roll 7 is a pressure-bonding roll with which the outermost polyolefin resin layer 4 constituting the uppermost layer of the composite resin 5 comes into contact, and is controlled to a temperature of 10 ° C. or higher and lower than 50 ° C.

  And when the manufacturing method of the resin coating metal plate of this invention is implemented using the said manufacturing apparatus 1, the temperature of the metal plate 2 at the time of contact with the maleic acid modified polyolefin is demonstrated for the metal plate 2 with the heating apparatus 9. FIG. Is heated to a temperature not lower than the temperature of the molten maleic acid-modified polyolefin resin and not higher than 340 ° C., and then the plurality of polyolefin resins 3 and 4 from the T-die 6 for coextrusion are applied to the heated metal plate 2. A composite resin 5 is laminated by extrusion in a molten state, and a pair of a first roll 7 and a second roll 8 in which the metal plate on which the composite resin 5 is formed is controlled to a temperature of 10 ° C. or more and less than 50 ° C. Resin-coated metal having excellent resin adhesion by pressing the outermost polyolefin resin layer 4 constituting the uppermost layer of the composite resin 5 with the rolls 7 and 8 so as to come into contact with the peripheral surface of the first roll 7. Made board 10 It can be. In order to heat the metal plate 2 at the time of contact with the maleic acid-modified polyolefin so that the temperature is higher than the temperature of the molten maleic acid-modified polyolefin and not higher than 340 ° C., the metal plate and the maleic acid-modified polyolefin are heated. A relationship between the temperature of the metal plate 2 at the contact location and the heating temperature in the heating device 9 may be obtained in advance, and the heating temperature in the heating device 9 may be determined.

  FIG. 2 schematically shows a production apparatus 11 for carrying out another method for producing a resin-coated metal plate according to the present invention. Specifically, the production apparatus 11 is extruded as a method for coating the composite resin 5. In this case, both the laminating method and the film laminating method are used. 2 denote the same parts as those constituting the manufacturing apparatus shown in FIG.

  The manufacturing apparatus 11 shown in FIG. 2 is basically the same as the configuration of the manufacturing apparatus 1 shown in FIG. 1, but only the innermost polyolefin resin layer 3 constituting the composite resin 5 is formed by the extrusion laminating method. In order to form the outermost polyolefin resin layer 4 constituting the composite resin 5 by a film laminating method in addition to the single layer extrusion T die 12 instead of the coextrusion T die 6 shown in FIG. A film supply reel 14 for supplying the resin film 13 is further provided. FIG. 2 shows a case where the polyolefin resin constituting the composite resin 5 has two layers, but in the case of three or more layers, the film laminating method and the extrusion laminating method may be appropriately combined. From the viewpoint of work efficiency, it is preferable to use the coextrusion T die 6 shown in FIG. 1 instead of the single layer extrusion T die 12.

  As the metal plate, various surface-treated steel plates can be used in addition to a steel plate, an aluminum plate and the like. As the surface-treated steel sheet, a steel sheet plated with tin, zinc or the like, a steel sheet subjected to chemical conversion treatment such as chromic acid treatment or phosphate treatment, a steel plate combining these several types of treatment, or the like can be used. Although the dimensions of these steel plates are not particularly defined, a strip-like shape that can be wound in a coil shape can be continuously processed in large quantities, which is preferable from the viewpoint of productivity and application.

  The temperature of the metal plate (hereinafter referred to as the preheating temperature of the metal plate) when contacting the molten maleic acid-modified polyolefin resin is the temperature of the molten maleic acid-modified polyolefin. As described above, it is necessary to heat in advance so that the temperature is 340 ° C. or lower.

  By setting the preheating temperature of the metal plate to be equal to or higher than the temperature of the molten maleic acid-modified polyolefin, the wetness at the time of contact between the molten maleic acid-modified polyolefin resin and the metal plate becomes sufficient, which greatly contributes to adhesion. When the preheating temperature of the metal plate is lower than the temperature of the molten maleic acid-modified polyolefin resin, the wet state between the molten maleic acid-modified polyolefin resin and the metal plate becomes insufficient, and good adhesion cannot be obtained. More preferably, the temperature is higher than that of the molten maleic acid-modified polyolefin. Here, in order to set the preheating temperature of the metal plate to be equal to or higher than the temperature of the maleic acid-modified polyolefin resin in the molten state, the temperature should be equal to or higher than the temperature of the maleic acid-modified polyolefin resin when extruded from the T die.

  Conventionally, in the extrusion laminating method, it has been considered preferable to set the preheating temperature of the metal plate to about the temperature of the molten resin or less in order to avoid decomposition of the resin.

  However, in the present invention, there is no problem even if the preheating temperature of the metal plate is equal to or higher than the temperature of the molten maleic acid-modified polyolefin resin extruded from the T die. The reason for this is not clear, but the use of maleic acid-modified polyolefin resin as the innermost polyolefin resin in the molten state to be brought into contact with the metal plate, and the first pressure bonding after contacting the molten resin with the metal plate Controlling the temperature of the first roll on the side in contact with the outermost polyolefin resin in the pair of rolls that are considered to be related to the ability to increase the preheating temperature of the metal plate.

  The preheating temperature of the metal plate is more preferably the melting point of maleic acid-modified polyolefin to be brought into contact with the metal plate + 50 ° C. or more in order to improve the wettability between the maleic acid-modified polyolefin resin and the metal plate.

  On the other hand, when the preheating temperature of the metal plate exceeds 340 ° C., cooling with a first roll (for example, a metal roll) described later, the temperature drop is insufficient, so the outermost polyolefin constituting the composite resin formed on the metal plate As a result of not being able to sufficiently solidify the resin, the outermost polyolefin resin is easily wound around the first roll, making it difficult to continue the operation.

  In addition, as a means to heat a metal plate, all well-known methods, such as electricity heating, electromagnetic induction heating, and heating with a heater, can be used, for example. In addition, it is preferable that the heating device is provided at a position immediately before the metal plate comes into contact with the molten resin in terms of suppressing a temperature drop of the metal plate after the heating until the molten resin is brought into contact.

  The adhesion between the metal plate and the composite resin is enhanced by press-bonding with a pair of rolls composed of a first roll and a second roll. Of the rolls forming the press-bonding, the outermost polyolefin in a molten state It is necessary to control the temperature of the first roll, which is the roll in contact with the resin, to 10 ° C. or more and less than 50 ° C. When the temperature of the first roll is less than 10 ° C., the amount of heat transferred from the molten resin and the metal plate to the first roll increases, and the amount of heat necessary for the adhesion between the molten resin and the metal plate is insufficient. The temperature must be 10 ° C or higher. Further, if the temperature of the first roll is set to 50 ° C. or higher, the ability to cool the molten resin is insufficient, and the wrapping of the resin around the first roll occurs. Keep at 45 ° C or lower.

  The material of the first roll is preferably a material having excellent thermal conductivity, and examples thereof include metals such as steel and aluminum. If the material of the first roll is a rubber material or the like, it is inferior in heat conduction, and as a result of the surface temperature of the first roll rising rapidly due to contact with the resin-coated metal plate, the temperature of the first roll is less than 50 ° C. This is because it becomes difficult to control the temperature and the resin is likely to be wound.

  In addition, it is preferable that the 2nd roll located in the side which contacts a metal plate consists of material with small heat conductivity in order to maintain the calorie | heat amount of a metal plate, and in addition, resin protruded from the metal plate to the 2nd roll From the viewpoint of preventing the wrapping of the second roll, it is preferable that at least the surface of the second roll is made of a material to which resin is difficult to adhere, such as silicon rubber.

  A pair of rolls to be crimped may be composed of a plurality of pairs of rolls in addition to the case of being composed of a pair of rolls as shown in FIG. The formed roll may be configured as described above.

  In the present invention, the uppermost layer of the composite resin is formed by a pair of rolls composed of a first roll and a second roll in which the metal plate on which the composite resin is formed is controlled to a temperature of 10 ° C. or higher and lower than 50 ° C. The outermost polyolefin resin layer to be formed is pressure-bonded so as to be in contact with the first roll, and after the pressure bonding, the contact state between the metal plate and the first roll is less than one rotation. It is necessary to maintain until it rotates in the range.

  The temperature-controlled first roll is brought into contact not only at the time of pressure bonding but over a predetermined period after pressure bonding, specifically, a period until the pressure bonding position of the first roll rotates in a range of less than one rotation, By continuously cooling the resin and the metal plate, the cooling means after pressure bonding, which has been conventionally required, becomes unnecessary. At this time, the contact state between the metal plate after the crimping and the first roll is preferably maintained until the crimping position of the first roll is rotated by a quarter or more in that sufficient cooling is obtained. Then, it is conveyed to the next process.

  Examples of the maleic acid-modified polyolefin resin that forms the innermost polyolefin resin layer include maleic acid-modified polyethylene resin and maleic acid-modified polypropylene resin.

  As the polyolefin resin forming the outermost polyolefin resin layer, all polyolefin resins that can be formed can be used. Of these, polyethylene and polypropylene are suitable. As described above, the outermost polyolefin resin layer can be formed by either an extrusion laminating method or a film laminating method.

  In the present invention, as each polyolefin resin layer constituting the composite resin, a resin to which various components are added may be used in order to improve various characteristics within a range not impairing the effects of the present invention.

[Example 1]
As the metal plate, an electrolytic chromic acid-treated steel strip having a thickness of 0.2 mm and a width of 300 mm was used. This steel strip was subjected to electrolytic chromic acid treatment as chromic acid treatment on both sides of the cold rolled steel strip. The electrolytic chromic acid treatment is performed on the same line with the treatment liquid composition and treatment conditions shown in Table 1 and then continuously with the treatment liquid composition and treatment conditions shown in Table 2 to form a chemical conversion film (chromium). An adhesion amount of 115 mg / m ² ) was formed. The electrolytic chromic acid-treated steel strip is heated with an infrared heater so that the preheating temperature becomes 260 ° C., and then, using an extruder equipped with two short shaft screws and a T-die for coextrusion (feed block method). Steel strip so that methylene acid-modified polyethylene having a melting point of 107 ° C. and a modification amount of 0.5% by mass is in contact with the steel strip, and low density polyethylene having a melting point of 127 ° C. (density 0.93 g / cm ³ ) is the upper layer. The composite resin was laminated (coated) by continuously extruding to one side. Extrusion lamination conditions are: T-die lip width 400 mm, lip opening 0.5 mm, air gap (distance from T-die outlet to laminate) 80 mm, resin discharge 10 kg / h (maleic acid-modified polyethylene 5 kg / h, low Density polyethylene 5 kg / h), line speed 6 m / min. The resin temperature during extrusion was 210 ° C. The crimping of the steel strip and the resin was performed by using a pair of rolls and causing the molten resin to flow between the rolls through which the steel strip passes in the same manner as shown in FIG. The first roll was made of metal (steel chrome plating roll), and the second roll was a roll covered with silicon rubber. The temperature of the first roll for pressure-bonding the resin to the steel strip was controlled at 30 ° C. by circulating water inside. After maintaining the contact state between the steel strip after the press-bonding and the first roll until the press-bonding position of the first roll was rotated by 3/8, it was conveyed to the next step.

[Example 2]
Resin coating was performed in the same manner as in Example 1 except that a steel plate having a thickness of 0.2 mm and a width of 300 mm was applied to tin plating (adhesion amount 2.8 g / m ² ) as a metal plate. A metal plate was produced. Table 3 shows the treatment liquid composition and treatment conditions for the tin phosphate treatment.

[Example 3]
A resin-coated metal plate was produced in the same manner as in Example 1 except that an aluminum strip having a thickness of 0.2 mm and a width of 300 mm was used as the metal plate.

[Example 4]
As the polyolefin resin, a maleic acid-modified polypropylene was used on the side in contact with the steel strip, and the upper layer was polypropylene, and a resin-coated metal plate was produced in the same manner as in Example 1 except that the resin temperature during extrusion was 240 ° C. .

[Example 5]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the preheating temperature of the steel strip was 210 ° C.

[Example 6]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the preheating temperature of the steel strip was 340 ° C.

[Example 7]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the resin temperature during extrusion was 180 ° C. and the preheating temperature of the steel strip was 203 ° C.

[Example 8]
Resin coating was performed in the same manner as in Example 1 except that the temperature of the first roll was controlled at 15 ° C.

[Example 9]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the temperature of the first roll was controlled at 45 ° C.

[Example 10]
The same method as in Example 1 except that the contact state between the steel strip after the press-bonding and the first roll is maintained until the press-bonding position of the first roll makes a quarter turn and then conveyed to the next step. A resin-coated metal plate was produced.

[Example 11]
A resin-coated metal plate was produced in the same manner as in Example 1 except that a low-density polyethylene to be laminated on the upper layer of maleic acid-modified polyethylene was formed by a film lamination method using a film previously formed to a thickness of 20 μm. .

[Comparative Example 1]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the resin temperature during extrusion was 180 ° C. and the preheating temperature of the steel strip was 170 ° C.

[Comparative Example 2]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the preheating temperature of the steel strip was 205 ° C.

[Comparative Example 3]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the preheating temperature of the steel strip was 350 ° C.

[Comparative Example 4]
Resin coating was performed in the same manner as in Example 1 except that the temperature of the first roll was controlled at 5 ° C.

[Comparative Example 5]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the temperature of the first roll was controlled at 55 ° C.

[Comparative Example 6]
A resin-coated metal plate was produced in the same manner as in Example 1 except that the steel strip after the crimping was transported to the next process without being brought into contact with the first roll.

The production conditions for the examples and comparative examples are summarized in Table 4. Each resin-coated metal plate thus obtained was evaluated for adhesion by an Erichsen test. The procedure is described below.
As shown in FIG. 3, two 50 mm × 50 mm test pieces 15 are vertically and horizontally spaced at a distance of 2.5 mm across the center position 17 of the test piece 15. Make a cut 18 of. A sharp blade is used to form the cut 18 and only the resin coating layer (composite resin) is cut. The punch of the Eriksen tester specified in JIS B 7729 is aligned with the center position of the test piece, and 6 mm extrusion is performed so that the laminate surface is convex. The test piece is allowed to stand at room temperature for 24 hours, and it is examined whether or not the resin has been peeled off visually. The superiority or inferiority of the resin adhesion was evaluated in five stages according to the following criteria. Table 5 shows the evaluation results of the resin film thickness and the resin adhesion for the inventive examples and the comparative examples.
<Evaluation criteria for resin adhesion>
1: When peeling is seen over the entire surface of the convex processing part 2: When peeling is seen along each incision 3: When peeling is seen only along the notch near the center part 4: Only at the intersection of the notches When peeling is observed 5: When no peeling is observed

The resin-coated metal plates of Examples 1 to 11 produced according to the present invention all showed good resin adhesion.
On the other hand, in Comparative Examples 1 and 2, the preheating temperature of the steel strip is too low, and in Comparative Example 4, the temperature of the first roll is too low. Since it was conveyed to the next process without being brought into contact with each other, the resin adhesion was poor. Moreover, since the preheating temperature of the steel strip is too high in the proportional example 3, the temperature of the first roll is too high in the comparative example 5, so that the molten resin is wound around the first roll, and the resin-coated metal plate (band) ) Was impossible to produce.

  According to the present invention, a polyolefin resin-coated metal plate having excellent resin adhesion can be produced at a relatively low cost.

It is a schematic diagram of the typical manufacturing apparatus for embodying the manufacturing method of the resin coating metal plate according to this invention. It is a schematic diagram of the other manufacturing apparatus for embodying the manufacturing method of the resin coating metal plate according to this invention. It is a top view for demonstrating the test piece used for an Erichsen test.

Explanation of symbols

1, 11 Production equipment for resin-coated metal plates 2 Metal plates (bands)
3 innermost polyolefin resin layer 4 outermost polyolefin resin layer 5 composite resin 6 T-die for coextrusion 7 first roll 8 second roll 9 heating device
10 Resin coated metal plate
12 Extruded T-die for single layer
13 Polyolefin resin film
14 Film supply reel
15 specimens
16 Resin coated surface
17 Specimen center position

Claims (3)

In the method for producing a resin-coated metal plate for coating a metal plate with a composite resin composed of a plurality of polyolefin resin layers,
Among the polyolefin resin layers constituting the composite resin, the innermost polyolefin resin layer positioned in contact with the metal plate is a temperature of the molten maleic acid-modified polyolefin resin in the molten state from the T die. Above, formed by extruding onto a metal plate at a temperature of 340 ° C or lower,
The outermost polyolefin resin constituting the uppermost layer of the composite resin with a pair of rolls composed of a first roll and a second roll in which the metal plate on which the composite resin is formed is controlled to a temperature of 10 ° C. or higher and lower than 50 ° C. The layer is pressure-bonded so as to be in contact with the first roll, and also after the pressure bonding, until the contact position between the metal plate and the first roll is rotated within a range of less than one rotation. A method for producing a resin-coated metal plate excellent in resin adhesion, characterized in that the method is maintained.   The method for producing a resin-coated metal plate with excellent resin adhesion according to claim 1, wherein the coating of the composite resin on the metal plate is performed by a coextrusion laminating method.   The said contact state of the metal plate after the said crimping | compression-bonding and a 1st roll is maintained until the said crimping | compression-bonding position of a 1st roll rotates by 1/4 or more, The Claim 1 or 2 characterized by the above-mentioned. A method for producing a resin-coated metal plate having excellent resin adhesion.

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