JP4659432B2 - Resin-coated metal plate with excellent releasability and method for producing the same - Google Patents

Description

  The present invention relates to a functional composite metal plate obtained by laminating or bonding a functional coating material such as gypsum board, urethane foam, or decorative paper to a resin-coated metal plate to improve the functionality. In particular, the present invention relates to an improved resin-coated metal plate and a method for producing the same so that the functional coating layer can be easily peeled off and easily recovered when the metal plate is collected and recycled as a used material.

  Regarding resin coatings for coating metal plates, many resin compositions have been proposed according to their uses and purposes. For example, Patent Document 1 discloses a coating composition containing a water-absorbing resin for the purpose of masking during painting. This coating composition exhibits a certain degree of hydrophilicity due to the action of the water-absorbing resin blended in the coating, but this coating film has a slow water permeation rate to the lamination interface. Even if it is applied as a release coating film for dismantling (peeling) and facilitating recovery and recycling, the peeling-promoting effect as intended in the present invention cannot be obtained.

  Patent Document 2 discloses a water-absorbing paint containing a resin binder, a water-insoluble water-absorbing resin powder, and a water-soluble organic compound or a salt thereof, and a water-absorbing material obtained by applying the paint to a base sheet. A functional sheet is disclosed. However, this water-absorbent sheet is used for waterproof cables, for example, and is intended to prevent further water ingress and running (diffusion) by swelling due to water absorption. There is no technical idea to promote and improve the peelability.

Further, Patent Document 3 discloses an invention relating to a magnet fixing adhesive that is different from the present invention. However, it has a technical idea relatively similar to that of the present invention. Is described, and an adhesive is described that has improved easy releasability when the magnet is peeled from the base sheet and recycled. However, when such an adhesive is applied to a precoat metal plate as intended by the present invention, the heat-expandable particles expand in the coating line. The peeling promoting effect is not exhibited.
Japanese Examined Patent Publication No. 61-17553 Japanese Patent Laid-Open No. 5-214268 JP 2003-176659 A

  The present invention has been made under the circumstances as described above, and the object thereof is to laminate or bond a functional coating material such as gypsum board, urethane foam, or decorative paper on a resin-coated metal plate as described above. When manufacturing composite metal plates with added functionality, the functional coating layer can be easily peeled off when the metal plates are collected as used materials and recycled. An object of the present invention is to provide a resin-coated metal plate modified so that it can be recovered and a method for producing the same.

  The resin-coated metal plate excellent in easy peelability according to the present invention that has solved the above problems is a resin-coated metal plate in which a coating resin layer is formed on the surface of the metal plate, and the coating resin layer is It is characterized by including a matrix resin, a water-absorbing polymer, and a water-permeable portion.

  The specific structure of the water-permeable portion in the resin-coated metal plate of the present invention is as follows: 1) a foam layer formed by applying a foaming agent to a metal plate and foaming, or 2) a hydrophilic nonwoven fabric layer And those formed by combining these 1) and 2) are preferable because they exhibit further excellent peelability.

  In addition, it is preferable to add a water-soluble resin as another component in the coating resin layer, since the peeling of the functional coating layer from the metal plate can be further promoted. The coating resin layer may have a single layer structure in which a layer containing a water-absorbing polymer and a water-permeable portion are combined, or at least two layers of the water-absorbing polymer-containing layer and the water-permeable portion. It may be of a multilayer structure made of

  Furthermore, as a coating material for forming the coating resin layer according to the present invention, a) matrix resin: 10 to 50% by mass, water-absorbing polymer: 40 to 80% by mass, and foaming agent: 3 to 50% by mass Or b) a matrix resin: 10-50 mass%, a water-absorbing polymer: 40-80 mass%, a foaming agent: 3-50 mass%, and a water-soluble resin: 10-50 mass% preferable.

  The production method according to the present invention is positioned as a preferred method for forming a coating resin layer using a paint containing a foaming agent as described above. The above-mentioned paint is applied to one or both surfaces of a metal plate and applied. It is characterized in that a water permeable part is formed in the coating resin layer by drying after foaming the foaming agent in the film.

  The resin-coated metal plate of the present invention has a water-absorbing polymer and a water-permeable portion in the matrix resin layer as described above, and water penetration and diffusion are remarkably accelerated in this portion. In addition, for example, a composite metal plate that has been enhanced by laminating or pasting functional coating materials such as gypsum board, urethane foam, and decorative paper to improve the functionality is collected, and the functional coating layer is peeled off to remove the metal. When recycling as a plate, the peeling operation between the functional coating layer and the metal plate can be remarkably simplified.

  In order to recover the metal plate by peeling the functional coating layer from the functional composite metal plate in which various functional coatings are formed on the metal plate as described above, it is necessary to reduce the adhesive force between the two. The simplest method for that purpose is to contain a water-absorbing polymer in the matrix resin constituting the coating film, and bring the bonding interface of the functional composite metal plate to be peeled into contact with water. This is a method of reducing the bonding force by swelling the coating film. However, even if only the edge of the bonding interface absorbs water and swells, the easy peelability (improvement of the peeling speed) cannot be improved unless the water absorption / swelling proceeds rapidly toward the center of the bonding interface. .

  Therefore, in the present invention, in addition to containing a water-absorbing polymer for water absorption / swelling together with the matrix resin in the resin coating layer, the water-permeable portion is provided so that water absorption / swelling can proceed rapidly toward the center of the bonding interface. Form.

  This water permeable portion exhibits an action of promptly inducing moisture invading from the edge of the functional composite metal plate to the direction of the central portion. A water-absorbing polymer and a foaming agent are blended in the matrix resin to be applied, and this is applied to a metal plate and then foamed to form a foamed layer, which is used as a water-permeable portion. That is, when a matrix resin is coated with a water-absorbing polymer and a foaming agent and then foamed, countless bubbles containing the water-absorbing polymer on the wall surface are formed in the matrix resin layer. Then, when water comes into contact with the bubble-containing layer, first, the water-absorbing polymer absorbs water and dissolves to break the wall surface of the bubble, and the water flows in the bubble toward the next wall surface and reaches the next wall surface. By destroying the wall surface and sequentially repeating this, the bubbles become water-permeable portions, and the wall surfaces of all the bubbles are destroyed by moisture. As a result, the functional coating and the metal plate formed thereon are easily peeled off with the paint coating layer as a boundary.

  As an example other than the above, it is also effective to form a water permeable portion with a hydrophilic nonwoven fabric layer. That is, in the case of this example, a hydrophilic nonwoven fabric is impregnated with a mixture of a matrix resin and a water-absorbing polymer, or is laminated to form a water permeable portion. In this example, the hydrophilic non-woven fabric is present in the matrix resin in contact with the water-absorbing polymer, and the hydrophilic polymer in the paint exposed at the joining edge between the functional coating and the metal plate. When water comes into contact with water, water adheres to the hydrophilic non-woven fabric in contact with the polymer, and water passes through the hydrophilic non-woven fabric and sequentially penetrates and penetrates from the side edge toward the central portion. The water-absorbing polymer in contact with the nonwoven fabric is swollen and dissolved, and the bonding force in the stacking direction is drastically reduced at this portion. As a result, the metal plate and the functional coating constituting the substrate can be easily peeled from the nonwoven fabric layer portion.

  In the present invention, as described above, the coating resin layer includes bubbles or hydrophilic non-woven fabric constituting the water-permeable portion and a water-absorbing polymer, and these actions make it possible for water to enter and diffuse quickly. The water-absorbing polymer not only has the effect of accelerating the penetration of water into the bonding interface, but also absorbs water and swells to produce a force in the peeling direction at the bonding interface with the metal plate. Therefore, peeling of the metal plate is further facilitated. At this time, if a water-soluble resin is contained in addition to the water-absorbing polymer as a constituent component of the coating, the diffusion rate to the bonding interface is further increased by water-absorbing and dissolving the water-soluble resin in addition to water absorption and swelling of the water-absorbing polymer. It is preferable because it is accelerated.

  In addition, the water-permeable portion and the water-absorbing polymer as described above can coexist in one coating layer, but in addition, a layer having a water-permeable portion and a layer containing the water-absorbing polymer are formed as separate layers, It is also possible to form a coating resin layer having a multilayer structure of two or more layers.

  In the case where the water-permeable portion is constituted by bubbles formed by foaming of the foaming agent as described above, the coating component for forming the bubble-containing layer includes 10 to 50% by mass of a matrix resin and a water-absorbing polymer 40 to 40%. It is desirable to use a paint containing 80% by mass and 3 to 50% by mass of a foaming agent, which is diluted with a solvent. By the way, when the amount of the matrix resin is relatively insufficient, it is difficult to form a coating film. Conversely, when the content ratio of the matrix resin is too large, the amount of other components, that is, the water-absorbing polymer and the foaming agent is relatively large. Therefore, the easy peelability cannot be sufficiently improved.

  Moreover, if the blending amount of the water-absorbing polymer and the foaming agent is too large, the easy peelability is improved, but it becomes difficult to form a coating film for coating. Conversely, if the blending ratio is too small, the peelability is sufficiently enhanced. Can not be.

  More preferable blending ratio of each component in consideration of both adhesion and easy peelability as a coating film for coating is 20 to 50% by mass of the matrix resin, 50 to 70% by mass of the water-absorbing polymer, and 10 to 50 of the foaming agent. It is in the mass% range.

  In the case of a paint containing a water-soluble resin as another component, for the same reason, the matrix resin is 10 to 50% by mass, the water-absorbing polymer is 40 to 80% by mass, the foaming agent is 3 to 50% by mass, and the water-soluble Resin: Used in a ratio of 10 to 50% by mass, and these may be used by dispersing or dissolving in a solvent. More preferable blending ratios are matrix resin: 20-40% by mass, water-absorbing polymer: 50-65% by mass, blowing agent: 10-40% by mass, and water-soluble resin: 10-30% by mass. In addition, when the compounding quantity of water-soluble resin is insufficient, there exists a tendency for the easy-peelability improvement effect to become somewhat insufficient, and conversely, when too large, there exists a possibility that coating-film adhesiveness may become insufficient.

  The “mass%” defining the content of the paint constituent component means the ratio of the foaming agent in the paint to the total solid component before foaming. Therefore, for use as a paint, the above components are diluted with water or a solvent as described later to a concentration of, for example, about 5 to 70% by mass.

  As described above, as a specific method for forming the water permeable part by foaming using a foaming agent, a paint having the above-described component composition is used, and this is applied to one or both surfaces of a metal plate. The method of drying after heating and foaming is recommended as the simplest method. Prior to applying these paints, a hydrophilic non-woven fabric is impregnated with the same or different resin liquid as the paint, and then the paint is further applied thereon to form a multilayered coating layer. It is also possible.

  In the present invention, various organic solvents can be used as the solvent for preparing the coating composition. Organic solvents that can be used include alcohols such as methanol, ethanol, isopropanol and butanol; ethers such as methyl cellosolve and ethyl cellosolve; ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol and propylene glycol And esters thereof, esters such as ethyl acetate and butyl acetate, hydrocarbons such as xylene and toluene, but of course are not limited thereto.

  The matrix resin is not particularly limited as long as it has film-forming properties and coating film adhesion as a coating forming component. For example, polyester resin, epoxy resin, polyamide resin, urethane resin, acrylic resin, vinyl These resins or various modified resins thereof can be arbitrarily selected and used.

  As the water-absorbing polymer, various polymers that swell by absorbing water can be used. Among them, starch modified with acrylic acid or acrylonitrile, PVA (polyvinyl alcohol), carboxymethylcellulose, polyacrylic acid is preferable. A highly water-absorbing polymer such as a salt system is particularly preferred, and a water-absorbing polymer capable of being finely divided, such as sodium polyacrylate, is particularly preferred.

  Examples of the blowing agent include azodicarbonamide, barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, 4,4-oxybis (benzenesulfonylhydrazide), hydradicarbonamide, diphenylsulfone-3,3-disulfonylhydrazide. Non-limiting examples include p-toluenesulfonyl semicarbazide, trihydrazinotriazine, biurea, sodium hydrogen carbonate, zinc carbonate, and various thermally expandable microcapsules and various foaming agent master batches.

  Specific examples of the water-soluble resin include various water-soluble resins such as PVA, starch, and cellulose.

  The resin-coated metal plate of the present invention is prepared by applying the paint prepared as described above to one or both sides of a metal plate and, when using a foaming agent, heating it to an appropriate temperature to cause foaming and drying. It is manufactured by forming a resin coating layer on the surface of the plate.

  When using a hydrophilic non-woven fabric as the water permeable part, attach a sheet-like non-woven fabric made of hydrophilic fibers to the surface of the metal plate and apply paint from the top, or impregnate the non-woven fabric with a paint component. A method of bonding to the surface of the metal plate may be employed. When the coating resin layer has a multilayer structure, for example, after the non-woven fabric impregnated with the coating component as described above is bonded to the metal plate or before that For example, a method may be employed in which a foaming agent-containing coating is applied and foamed to form a coating in layers.

  Specific examples of the hydrophilic fibers constituting the nonwoven fabric include cellulose fibers, hydrophilic polyester fibers, viscose rayon, etc., or other synthetic fibers such as acrylic fibers, which are subjected to water absorption treatment or the like to make them hydrophilic. All of the fibers that have been applied can be used. In particular, in the present invention, in order to provide water permeability quickly in contact with moisture, for example, a nonwoven fabric obtained by subjecting acrylic fiber or the like to water absorption treatment with a highly hydrophilic surfactant or the like is preferably used.

  There are no restrictions on the type of metal plate, and it includes cut plates and strip-like metal plates of any size. Specific examples include hot-rolled steel sheets, cold-rolled steel sheets, hot-dip galvanized steel sheets; alloyed hot-dip galvanized steel sheets. Examples thereof include, but are not limited to, various types of plated steel sheets such as electrogalvanized steel sheets and electro-Zn-Ni alloy-plated steel sheets; stainless steel sheets; non-ferrous metals such as aluminum, titanium, and zinc; In addition, with the aim of further improving the corrosion resistance and adhesion of metal plates, phosphate treatment, chromate treatment, pickling treatment, alkali treatment, electrolytic reduction treatment, cobalt plating treatment, nickel plating treatment, silane coupling treatment, inorganic Surface-treated metal plates that have undergone silicate treatment are also targeted.

  And when this resin-coated metal plate is put into practical use as a functional composite metal plate, an easily peelable coating resin layer is formed on one side or both sides of the metal plate as described above, and then a plaster board or urethane is formed thereon. What is necessary is just to form arbitrary functional coating layers, such as foam and decorative paper, and to make a composite metal plate. In addition, since the functional composite metal plate using the resin-coated metal plate of the present invention as a base material is easily peeled off from the functional coating layer and the metal plate when it is applied to a part in contact with water or a humid part due to its characteristics, Avoid the use to such a part as much as possible, and when you have to use it, seal the edge with a sealing material so that the joint edge is not directly exposed, and peel off the sealing material at the time of collection and recycling Thus, it is desirable that the peripheral edge is opened to provide easy peeling.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, and is suitable as long as it can meet the purpose described above and below. It is also possible to carry out with modification, and any of them is included in the technical scope of the present invention.

Example (Production Example 1 of Resin Coated Metal Sheet)
1) A polyester resin (trade name “Byron” manufactured by Toyobo Co., Ltd.) is used as a base resin, and a water-absorbing polymer and various additives are added and mixed uniformly to prepare a coating composition.
2) Apply the obtained paint to the surface of the steel sheet using an applicator (approx. 200 μm for the purpose of WET film thickness).
3) Next, the resin coating layer is formed by heating and drying in a hot air oven.
・ When a water-soluble resin is used in combination, heat at 150 ° C. for 5 minutes to dry.
-When a foaming agent is used In the case of the foaming agent A, it heats and dries at 150 degreeC x 5 minutes.
In the case of the foaming agent B, it is dried for one day and then heated to 150 ° C. for 5 minutes to cause foaming.
4) Adhesive (modified silicone resin adhesive manufactured by Konishi Co., Ltd., trade name “Silex”) using a coating bar with a 500 μm thick spacer sandwiched between the surfaces of the resulting resin-coated metal plate. Apply.
5) A 9.5 mm thick gypsum board (manufactured by Yoshino Gypsum Co., Ltd.) is pasted on it, and a weight is placed on it and air-dried for one week to obtain a functional composite metal plate.
6) To examine the easy peelability of the metal plate from the functional composite metal plate, a test piece of 15 cm × 7 cm was cut out from the center of the test plate in order to bring out the edge of the resin coating, and the following easy peelability Conduct an evaluation test.

(Production example 2 of resin-coated metal sheet)
1) A polyester resin (trade name “Byron” manufactured by Toyobo Co., Ltd.) solution is applied onto a steel plate using an applicator so that the dry film thickness is 75 μm.

  2) A non-woven fabric (trade name “Lan Seal” manufactured by Toyobo Co., Ltd., thickness of about 10 μm) is placed on the coating film.

  3) After volatilizing and removing the solvent, the polyester resin (trade name “Byron” manufactured by Toyobo Co., Ltd.) containing water-absorbent resin (trade name “SunFresh” manufactured by Sanyo Chemical Co., Ltd.) is applied with an applicator. Then, the solvent is volatilized again at about 150 ° C. for about 5 minutes (about 40 to 80 μm in total film thickness).

  4) An adhesive (modified silicone resin-based adhesive manufactured by Konishi Co., Ltd., trade name “CYREX”) is applied thereon with a bar coater with a 500 μm spacer sandwiched therebetween.

  5) A 9.5 mm thick gypsum board (manufactured by Yoshino Gypsum Co., Ltd.) is bonded onto the adhesive layer, and a weight is placed on it and air-dried for one week to obtain a functional composite metal plate.

  6) To examine the easy peelability of the metal plate from the functional composite metal plate, a test piece of 15 cm × 7 cm was cut out from the center of the test plate in order to bring out the edge of the resin coating, and the following easy peelability Perform the test.

Evaluation test (easy peelability);
The test piece of each functional composite metal plate obtained above is immersed in warm water maintained at 70 ° C., subjected to a high frequency of about 30 kHz, measured for the time until the gypsum board peels, and evaluated according to the following criteria. .
◎: peeled off in less than 10 minutes, ○: peeled off in 10 minutes or more and less than 30 minutes,
(Triangle | delta): It peels in 30 minutes or more, x: It does not peel.

  The results are collectively shown in Table 1.

  From Table 1, it can be analyzed as follows.

  Reference numerals 1 to 8 are examples that satisfy the requirements of the present invention, and have a water-permeable polymer and a water-permeable portion made of a foamed layer or a hydrophilic nonwoven fabric together with a water-absorbing polymer. Have. Among them, the symbols 3, 4, and 5 including the three of the water-absorbing polymer, the water-permeable portion, and the water-soluble resin have particularly excellent easy peelability.

  On the other hand, reference numerals 9 to 13 are comparative examples lacking one or more of the requirements defined in the present invention, and all have poor peelability. From these results, it can be seen that even if it contains a water-absorbing polymer or a water-soluble resin, it does not satisfy the level of easy peelability intended in the present invention unless it has a water-permeable portion.

  Also, in accordance with the above method, a resin binder, a water-absorbing resin, a foaming agent and a water-soluble resin are blended in the ratios shown in Table 2 below to prepare paints A to C, and each paint is applied onto a steel plate with an applicator. However, since the amount of the matrix resin was too small, it could hardly be formed.

Claims (4)

A resin-coated metal plate having a coating resin layer formed on a surface of a metal plate, the coating resin layer including a matrix resin, a water-absorbing polymer, a water-soluble resin, and a water-permeable portion, and the water-permeable portion is a matrix resin: By applying a paint containing 20 to 40% by mass, water-absorbing polymer: 50 to 60% by mass , foaming agent: 10 to 40% by mass and water-soluble resin: 10 to 30% by mass to a metal plate, and foaming. A resin-coated metal plate excellent in easy releasability, characterized by being formed bubbles. The resin-coated metal plate according to claim 1, further comprising a water-permeable portion formed by a hydrophilic nonwoven fabric layer . The coating resin layer is a resin-coated metal plate according to claim 1 or is composed of two or more layers having a layer and a water permeable portion comprising a water-absorbing polymer. A method for producing a resin-coated metal plate excellent in easy peelability, characterized in that the coating material according to claim 1 is applied to one or both surfaces of a metal plate, the foaming agent in the coating film is foamed and dried. .