JP2011201119A - Resin-coated metal sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin-coated metal sheet which is used in an insert molding or a hot press and is electro conductive.SOLUTION: The resin-coated metal sheet is laminated with an ornamental resin coating film on one surface of a metal sheet and an adhesive layer on the rear surface; wherein the resin-coated metal sheet can be connected with a plastic member and/or a metal member by an adhesive layer. The adhesive layer contains a resin of 30°C or more in glass transition temperature and a conductive filler whose ball tack at a pitch angle of 30° is 0 when measured at 100°C, and 5 or more when measured at 120°C.

Description

  The present invention relates to a resin-coated metal plate having a design resin coating on the front surface and an adhesive layer laminated on the back surface, and relates to a resin-coated metal plate used by being joined to a plastic member and / or a metal member. .

  A member in which a metal and a resin are combined is often used for home appliances and information devices. For example, Patent Document 1 discloses a composite member in which a urethane curable coating agent is applied to a metal plate, inserted into a mold for injection molding, and a polyamide-based resin composition is injected to be integrated. ing.

  There are many other similar techniques for insert molding. For example, Patent Document 2 describes a method of manufacturing an electronic device casing in which a rib portion and a boss portion are formed of resin by insert molding after applying an adhesive to a metal plate. Further, in Patent Document 3, a metal plate laminated or precoated with a thermoplastic resin is used for insert molding, and portions such as ribs and bosses are formed on the laminate layer or precoat layer. In any of these techniques, the resin applied to the metal plate is an insulator.

  Therefore, after forming the resin member by insert molding through the resin layer on the metal plate, even if the portion other than the resin member formed is joined to the metal plate, it cannot be made conductive. When a composite of a metal plate and a resin member is used for home appliances and information equipment, conductivity may be required to stabilize the operation of electronic devices and to block noise. Since the resin applied to the plate is an insulator, there is a problem that the conductivity cannot be secured unless the resin is removed.

JP-A-2005-67111 JP-A-7-124995 JP 2001-315162 A

  If the resin-coated metal plate used for insert molding has electrical conductivity, the resin-coated metal plate portion other than the portion where the resin member is formed by insert molding is connected to the internal electronics of home appliances and information equipment. In addition to stabilization of operation, resistance welding can be performed, which facilitates processing and reduces the cost of the product. However, a resin-coated metal plate that can be used for insert molding and has conductivity has not been known conventionally.

  Therefore, in the present invention, the provision of a resin-coated metal plate that can be used for insert molding and hot pressing and has conductivity is listed as an object.

  The present invention is a resin-coated metal plate in which a design resin coating film is laminated on the surface of a metal plate and an adhesive layer is laminated on the back surface, and the resin-coated metal plate is formed of a plastic member and / or by an adhesive layer. Bondable to a metal member, the adhesive layer contains a resin having a glass transition temperature of 30 ° C. or higher and a conductive filler, and has a ball tack of 30 ° when measured at 100 ° C., 120 When measured at ° C., the ball tack is 5 or more.

  The resin contained in the adhesive layer is preferably a polyurethane resin, a modified polyolefin resin, or a polyester resin. Also preferred is an embodiment in which the conductive filler is at least one selected from the group consisting of nickel, iron phosphide and magnetic powder. It is preferable that 10-40 mass% of this conductive filler is contained in the adhesive layer.

  Since the resin-coated metal plate of the present invention has an adhesive layer formed in advance, a step of applying an adhesive before insert molding is not necessary. In addition, since the adhesive layer does not peel from the metal plate during insert molding, insert molding can be performed with good yield. Furthermore, since the adhesive layer has conductivity, it can be conducted when another metal plate is laminated after insert molding, and welding is also possible. Therefore, it can be advantageously applied as an exterior cover of a product having an electric circuit inside such as home appliances and information equipment.

It is a schematic diagram which shows the measurement location of an electrical resistance value.

  In the resin-coated metal plate of the present invention, a design resin coating film is laminated on the front surface (Otemen), and an adhesive layer is laminated on the back surface. First, the adhesive layer which is the point of this invention is demonstrated.

[Adhesive layer]
The adhesive layer must have a conductive filler. Examples of the conductive filler include conductive layer-containing particles in which a conductive layer made of a metal or the like is formed on the surface of inorganic or organic polymer particles, and metal fine particles. In the present invention, it is preferable to use metal fine particles because the adhesive strength when heat-bonding to other members by molding or hot pressing (hereinafter sometimes simply referred to as heat-bonding) can be increased. Examples of the metal fine particles include nickel, iron phosphide, magnetic powder, zinc, aluminum, silver, and copper. Among these, nickel, iron phosphide, and magnetic powder are preferable. When there is a need to impart electromagnetic wave attenuation performance to the resin-coated metal plate of the present invention, it is preferable to use magnetic powder that has good conductivity and also has electromagnetic wave attenuation properties. Examples of such magnetic powder include permalloy (Ni-Fe alloy having a Ni content of 35% by mass or more) and sendust (Si-Al-Fe alloy).

  The conductive filler is preferably 10 to 50% by mass, more preferably 10 to 40% by mass, and more preferably 20 to 40% by mass when the total of the resin and the conductive filler in the adhesive layer is 100% by mass. % Is more preferable. If the amount is too large, the adhesiveness of the adhesive layer may be lowered. If the amount is too small, conductivity may not be exhibited.

  As the metal fine particles, those having an average particle diameter of 1 to 10 μm are preferably used. If it is smaller than 1 μm, the weldability is lowered, and if it exceeds 10 μm, the preferred film thickness of the adhesive layer is exceeded, which causes surface irregularities leading to a decrease in the adhesion area, which is not preferable. A more preferable range of the average particle diameter is 3 to 8 μm. In addition, an average particle diameter can be measured by a well-known method, such as observing with an electron micrograph etc.

  As the resin constituting the adhesive layer, polyurethane resin; (modified) polyolefin resin such as polypropylene and chlorinated polypropylene; thermoplastic polyester resin such as copolymer polyester; nylons; styrene resin; polyvinyl chloride resin Rubbers such as chloroprene rubber, urethane rubber and SBR; thermoplastic elastomers and the like. These may be cured with a known curing agent.

  Among these, polyurethane resins, modified polyolefin resins, and polyester resins are preferable. The polyurethane resin may be either a thermoplastic type or a partially thermoset type.

  The glass transition temperature (Tg) of the resin in the adhesive layer must be 30 ° C. or higher. When Tg is less than 30 ° C., an adhesive layer adheres to a mold or the like during heat bonding and peels off from the metal plate of the base material. However, if the Tg is too high, the tack development temperature, which will be described later, becomes too high and the adhesiveness becomes poor.

  The adhesive layer must have a tack development temperature of more than 100 ° C. During insert molding, the mold is heated to around 100 ° C. At this time, if there is a part where the resin-coated metal plate and the mold are in contact, the adhesive layer adheres to the mold and the base metal plate It is because it will peel from. The onset temperature of the tack is confirmed by ball tack. That is, when the ball tack test was performed by heating the adhesive layer to 100 ° C., there was no ball that stopped on the adhesive layer (ball tack was 0), and tack was developed when the temperature was 120 ° C. The adhesive layer has a ball tack of 5 or more. The ball tack test is performed by the tilting ball tack method defined in JIS Z 0237, and the tilt angle is 30 °. In addition, heating of an adhesive bond layer is possible if a silicone rubber heater etc. are arrange | positioned under the resin coating metal plate (designing resin coating-film surface side).

  In order to increase the tack development temperature above 100 ° C., as described above, it is necessary to use a resin having a Tg of 30 ° C. or higher.

  In addition, the adhesive layer may contain known additives such as an adhesion-imparting agent and an ultraviolet absorber.

[Designable resin film]
The design resin coating film is a resin coating film colored with a known pigment. As the resin, polyester resins, acrylic resins, polyurethane resins, epoxy resins, melamine resins, and the like are preferable. These are preferably cured with a curing agent. Since the resin-coated metal plate of the present invention is often press-molded, a polyester resin excellent in workability is preferable. In the case of a polyester resin, it can be cured with a melamine resin or the like. The curing agent is preferably blended so as to be 0.5 to 30% by mass (more preferably 5 to 25% by mass) when the total of the resin and the curing agent is 100% by mass.

  Examples of the pigment include inorganic pigments such as titanium dioxide, zinc white, and carbon black, and organic pigments such as azo and phthalocyanine.

  If the film thickness of the designable resin coating film is too thick, the workability deteriorates, so about 5 to 50 μm is preferable and 10 to 30 μm is more preferable.

[Metal plate]
The metal plate that can be used in the present invention is not particularly limited as long as resistance welding is possible, such as a steel plate or a non-ferrous metal plate, or a plated metal plate obtained by plating a single metal or various alloys on these. included. Specifically, for example, steel plates such as hot-rolled steel plates, cold-rolled steel plates, stainless steel plates, etc .; Examples thereof include non-ferrous metal plates such as aluminum, titanium, and zinc, or plated non-ferrous metal plates obtained by plating them. These may be subjected to, for example, phosphate treatment, chromate treatment, pickling treatment, alkali treatment, electrolytic reduction treatment, silane coupling treatment, inorganic silicate treatment, etc. as surface treatment.

[Production method]
In order to produce the resin-coated metal plate of the present invention, it is preferable to employ a method in which a composition for a designable resin coating film and a composition for an adhesive layer are prepared, and these are applied to a metal plate and dried. As the composition for a designable resin coating film, a resin, a pigment, and a curing agent or an additive that are added as necessary are diluted with an organic solvent to obtain a viscosity suitable for coating. Moreover, the composition for adhesive layers uses what diluted the resin, the electroconductive filler, the hardening | curing agent added as needed, an additive, etc. with the organic solvent etc.

  The organic solvent is not particularly limited, but aromatic hydrocarbons such as toluene and xylene; aliphatic esters such as ethyl acetate and butyl acetate; alicyclic hydrocarbons such as cyclohexane; aliphatic carbonization such as hexane and pentane. Hydrogen etc .; Ketones such as methyl ethyl ketone and cyclohexanone are listed. These may be used as a mixture.

  Various known additives used in the field of resin-coated metal sheets, such as matting agents, rust preventives, anti-settling agents, and waxes, may be added to the above-mentioned composition for designable resin coating films. You may add the well-known additive, rust preventive agent, etc. which are known in the conductive adhesive field | area to the said composition for adhesive bond layers.

  The method for applying each of the above compositions to the metal plate is not particularly limited, and a bar coater method, a roll coater method, a spray method, a curtain flow coater method, or the like can be employed. Either the design resin coating composition or the adhesive layer composition may be applied to the metal plate first, or both may be applied at once. The design resin coating film is molecularly designed to have better heat resistance than the adhesive layer, and even when subjected to two thermal histories, the effect is small. It is preferable to apply.

  After application, heat drying is performed. The heating temperature is not particularly limited, and when a curing agent is included, baking may be performed at the curing temperature.

[Heat bonding]
The resin-coated metal plate of the present invention can be bonded to a plastic member by insert molding or hot pressing. In addition, since the resin-coated metal plate of the present invention is configured such that tack does not appear at 100 ° C. and tack appears at 120 ° C. or higher, the adhesive layer is 120 ° C. or higher in heat bonding. Perform under conditions. After cutting the resin-coated metal plate to a predetermined size, usually bending, placing the design resin coating surface in contact with the mold in the mold for injection molding, and performing injection molding An insert-molded product is obtained. As a plastic material used for injection molding, any thermoplastic resin known in the field of injection molding can be used. Moreover, it can also join to a plastic member also by arrange | positioning the design resin film surface in contact with a hot press on the heated hot press, mounting a plastic member, and pressing from the top. At this time, when the plastic member is not bonded to the entire surface of the resin-coated metal plate after cutting, it is possible to bond another plastic member or metal plate to a portion where the plastic member is not bonded.

  The present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the present invention, and modifications within the scope of the present invention are included in the present invention. Unless otherwise specified, “%” indicates “mass%” and “part” indicates “part by mass”.

Experiment No. 1
[Metal plate]
An electrogalvanized steel sheet (EG) having a thickness of 0.6 mm was used as the original sheet. Plating was performed on both surfaces of the metal plate, and the adhesion amount was 20 g / m ^{2 on} each side. The plated steel sheet was subjected to a ground treatment using “CTE-213” manufactured by Nihon Parkerizing Co., Ltd. so that the adhesion amount was 100 mg / m ² .

[Lamination of design resin film]
20 parts by mass of melamine resin ("Summar (registered trademark) M-40ST": manufactured by Sumitomo Chemical Co., Ltd .: xylene solution; solid content 80%) in 100 parts by mass of polyester resin "Byron (registered trademark) 296" manufactured by Toyobo Co., Ltd. 10 parts by mass of titanium dioxide (“JR-603”; manufactured by Teica; average particle size 0.28 μm) and an appropriate amount of xylene / cyclohexanone (mass ratio 50:50) were added and mixed well, A composition for an adhesive resin coating film was prepared.

  This composition for design resin coating film was applied to one side of the steel plate with a bar coater so that the coating thickness was 20 μm, and baked in a baking oven for 60 seconds. The ultimate plate temperature was 230 ° C. A coated steel sheet on which a design resin film was laminated was produced.

(Lamination of adhesive layer)
Chlorinated polypropylene resin (“Hamatite (registered trademark) Y-6360”; manufactured by Yokohama Rubber; solid content 8%; Tg 80 ° C.) and Fe—Ni alloy magnetic powder (Mitsubishi Steel Permalloy; 78Ni-1Mo-FP; average) Particle diameter 7.6 μm; abbreviated as Fe—Ni in the table, nickel powder (“CNS-10” manufactured by Nikko Rica Co., Ltd .; average particle diameter 6.3 μm), or iron phosphide powder (manufactured by Fukuda Metal Foil Industry Co., Ltd.) P-Fe-350 "was pulverized with a pulverizer so that the average particle size was 7.0 m; abbreviated as FeP in the table) was added as a conductive filler to the concentration shown in Table 1 and adhered. An agent layer composition was prepared.

  This adhesive layer composition was applied to the opposite surface of the above-mentioned design-coated film-laminated steel sheet with a bar coater so that the film thickness was 10 μm, and baked in a baking furnace for 60 seconds. The ultimate plate temperature was 230 ° C. A resin-coated steel sheet was obtained.

[Ball tack]
The tilting ball tack method defined in JIS Z 0237 was used, and the tilt angle was 30 °. The adhesive layer was heated by placing a silicone rubber heater or the like on the lower side of the resin-coated metal plate (designed resin film surface side). Measurements were made at 100 ° C. and 120 ° C., and the results are shown in Table 1.

〔Breaking strength〕
The resin-coated steel sheet was cut into a 20 mm × 100 mm strip and placed on a hot press heated to 180 ° C. so that the design resin coating film was in contact with the hot press and left for 5 minutes. Similarly, a polypropylene sheet (thickness 1 mm) cut into a strip of 20 mm × 100 mm is placed on a heated resin-coated steel sheet so that the overlapped portion is 20 mm × 20 mm, and pressed at a pressure of 1 MPa for 30 seconds. A test piece was prepared. The obtained test piece was pulled at a tensile speed of 10 mm / min in an environment at an ambient temperature of 23 ° C. to determine the breaking strength. The results are shown in Table 1.

[Electric resistance value]
As shown in FIG. 1, an electrogalvanized steel sheet (20 mm × 40 mm) was placed on a portion where the resin-coated steel sheet and the polypropylene sheet did not overlap, and the electrical resistance values at points A and B were measured with a tester. The results are shown in Table 1.

  As is apparent from Table 1, the examples of the present invention showed zero ball tack at 100 ° C., but showed 5 or more at 120 ° C. The breaking strength was about the same. Moreover, since the adhesive bond layer contains a conductive filler, the embodiment of the present invention has a low electric resistance value. In Comparative Example 1 in which the conductive filler was not blended in the adhesive layer, the electric resistance was at a level that could not be measured.

Experiment No. 2
Except for changing to the adhesive layer having the structure shown in Table 2, the experiment No. In the same manner as in No. 1, a resin-coated steel plate was produced. In Table 2, “Byron (registered trademark)” is an organic solvent-soluble amorphous polyester resin manufactured by Toyobo Co., Ltd. In addition, “UBS” of the conductive filler is silver plated glass beads (“UBS-0010LAg”; average particle diameter of 6.1 μm) manufactured by Unitika. The evaluation results are also shown in Table 2. The breaking strength test was performed in the same manner as described above except that a polyethylene terephthalate sheet (thickness 1 mm) was used instead of the polypropylene sheet. Tg is a value obtained by the following method.

[Tg]
Based on JIS K7121, it measured using the differential scanning calorimeter (Thermo Pris DSC8230; made by Rigaku Corporation). Specifically, the adhesive layer was collected, set in a differential scanning calorimeter, cooled to −100 ° C., and when stabilized, the temperature was raised to 180 ° C. at 20 ° C./min. From the obtained DSC curve , Tg was determined.

  The comparative example using polyester with low Tg already has a high ball tack value at 100 ° C, and it can be confirmed that there is a large possibility of causing problems such as mold adhesion when heat bonding such as insert molding is performed. It was. In addition, the example using silver-plated glass beads has a lower breaking strength than other conductive fillers when any resin is used, but glass beads have a lower thermal conductivity than other conductive fillers. This is probably because the adhesive layer could not be sufficiently softened at the time of pressure bonding and the adhesion area could not be secured.

Experiment No. 3
For Comparative Examples 2 to 4, 6 to 8, and Examples 10 to 12, steel sheet adhesion tests were performed assuming the presence or absence of mold adhesion. The results are shown in Table 3.

[Steel adhesion]
A test piece having the same size as the break strength test was cut out, placed on a hot press heated to 100 ° C. so that the design resin coating film was in contact with the hot press, and left for 5 minutes. Similarly, a galvanized steel sheet (thickness 1 mm) cut into a strip shape of 20 mm × 100 mm was placed on a heated resin-coated steel sheet so that the overlapped portion was 20 mm × 20 mm, and pressed at a pressure of 1 MPa for 30 seconds. Then, it was allowed to cool to room temperature. Then, it was investigated whether the steel plate piled up and the adhesive bond layer of the resin coating steel plate adhered.

  As is apparent from Table 3, all of the comparative examples assumed to be attached to the mold adhered to the steel sheet, but the adhesive layer of the example does not exhibit tack at 100 ° C. It did not adhere.

Experiment No. 4
The configuration of the adhesive layer was changed as shown in Table 4. In this experiment, it was examined by the following method whether the adhesive layer would cohesively break and peel from the steel plate together with the film placed thereon. The results are shown in Table 4.

[Film adhesion]
A test piece having the same size as the breaking strength test was cut out, placed on a hot press heated to 120 ° C. so that the design resin coating film was in contact with the hot press, and left for 5 minutes. Next, a 30 mm × 150 mm polyester film (thickness 25 μm; manufactured by Unitika; Emblet (registered trademark) standard type) was placed on the adhesive layer and heated at 120 ° C. with a hot press upper die at a pressure of 1 MPa. Pressed for seconds. Immediately thereafter, the polyester film overlaid thereon was sandwiched and lifted with tweezers, and the adhesion state of the film, the adhesive layer and the steel plate was confirmed.

  In the comparative examples, the polyester film was peeled off from the steel sheet due to cohesive failure of the adhesive layer, but in the examples, all were in a beautiful bonded state.

  Since the resin-coated metal plate of the present invention is excellent in adhesiveness at an appropriate temperature, insert molding and hot pressing are possible without causing troubles such as adhesion of a mold. Moreover, the electroconductivity of the level which can be resistance heating welding is shown. Therefore, it is useful for exterior covers of home appliances and information devices.

Claims (4)

A resin-coated metal plate in which a design resin coating film is laminated on the surface of a metal plate and an adhesive layer is laminated on the back surface,
The resin-coated metal plate can be joined to a plastic member and / or a metal member by the adhesive layer,
The adhesive layer contains a resin having a glass transition temperature of 30 ° C. or more and a conductive filler, and has a ball tack of 30 ° when measured at 100 ° C. and 0 when measured at 120 ° C. A resin-coated metal plate having a tack of 5 or more.   The resin-coated metal sheet according to claim 1, wherein the resin contained in the adhesive layer is any one of a polyurethane resin, a modified polyolefin resin, and a polyester resin.   The resin-coated metal plate according to claim 1 or 2, wherein the conductive filler is at least one selected from the group consisting of nickel, iron phosphide, and magnetic powder.   The resin-coated metal sheet according to any one of claims 1 to 3, wherein the conductive filler is contained in an amount of 10 to 40% by mass in the adhesive layer.