JP2013086357A - Composite for which coated stainless steel plate and molded body of polycarbonate resin composition are bonded, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite which is one wherein a coated stainless steel plate and a molded body of a polycarbonate resin composition are bonded, and is excellent in joining property, and can be manufactured by the pre-coating method.SOLUTION: The coated stainless steel plate includes a stainless steel plate, a chemical treatment film, an undercoating film, and a top coating film. The undercoating film consists of the hardened material of a self-crosslinking type epoxy based resin composition, the hardened material of a non-self-crosslinking type epoxy based resin composition, or the hardened material of a polyester based resin composition. The top coating film consists of the hardened material of a polyester based resin composition including a polyester resin which contains a crosslinking functional group of which the number average molecular weight is 10,000 to 30,000, and an isocyanate, and also, of which the mass ratio of the polyester resin and the isocyanate is 70:30 to 95:5. The total film thickness of the undercoating film and the top coating film is 20 μm or lower.

Description

  The present invention relates to a composite in which a coated stainless steel plate and a molded article of a polycarbonate resin composition are joined, and a method for producing the same.

  A composite in which a metal plate and a molded body of a resin composition are joined has higher strength than a component made only of resin, and is used in various applications such as a mobile phone and a personal computer.

  Conventionally, such a composite has been manufactured by fitting a metal plate and a molded body of a resin composition. However, such a manufacturing method has many work processes and low productivity. Therefore, in recent years, it is common to manufacture a composite by joining a metal plate and a molded body of a resin composition by insert molding.

  When producing a composite by insert molding, it is important to improve the adhesion between the metal plate and the molded body of the resin composition. As a method for improving the adhesion between the metal plate and the molded body of the resin composition, for example, it is proposed to laminate a resin film on the surface of the metal plate before insert molding (see Patent Document 1). . Thus, by laminating the resin film on the surface of the metal plate, the adhesion between the metal plate and the molded body of the resin composition can be improved. However, the laminated metal plate has a problem that the resin film is easily peeled off from the metal plate when forming (for example, pressing).

  As a method for solving the above problem, a method of forming a resin coating film (adhesive layer) on the surface of a metal plate after forming has been proposed (see Patent Document 2). In the method described in Patent Document 2, since a resin coating film (adhesive layer) is formed after the metal plate is molded (post-coating method), there is no problem of peeling of the resin coating film by the molding process.

JP 2010-162758 A JP 2009-073088 A

  In the case of producing a composite using the method described in Patent Document 2, it is conceivable to use a stainless steel plate as a metal plate in order to improve strength and corrosion resistance. However, since the stainless steel plate has a passive film on its surface, the adhesion of the resin coating film (adhesive layer) is poor. For this reason, when a stainless steel plate is used in the method described in Patent Document 2, the adhesion between the stainless steel plate and the molded body of the resin composition may be insufficient. Moreover, since the method described in Patent Document 2 is a post-coating method in which a resin coating film (adhesive layer) is formed after a metal plate is molded, there is a problem that productivity is low.

  The present invention has been made in view of this point, and is a composite in which a coated stainless steel plate and a molded body of a polycarbonate resin composition are joined, and has excellent adhesion and can be manufactured by a precoat method. It is an object to provide a complex that can be produced.

  The present inventors have found that the above problems can be solved by forming a chemical conversion coating on the surface of the stainless steel plate and adjusting the composition and film thickness of the resin coating, and further studies are completed to complete the present invention. I let you.

That is, the present invention relates to the following composites.
[1] A composite in which a coated stainless steel plate and a molded body of a polycarbonate resin composition are joined: the coated stainless steel plate includes a stainless steel plate and a chemical conversion formed on the surface of the stainless steel plate. The undercoating film formed on the treated film, the chemical conversion film, and the overcoating film formed on the undercoating film, wherein the undercoating film is a phenoxy resin or an epoxy resin A cured product of a self-crosslinking epoxy resin composition containing phenoxy resin or a cured product of an epoxy resin composition containing an epoxy resin and a curing agent, or a polyester resin and isocyanate containing a crosslinkable functional group A cured product of a polyester-based resin composition containing; the top coat film has a crosslinkable functional group having a number average molecular weight of 10,000 to 30,000. A polyester resin composition containing a polyester resin and an isocyanate, and a mass ratio of the polyester resin to the isocyanate of 70:30 to 95: 5; a total of the undercoat film and the topcoat film A composite having a film thickness of 20 μm or less.
[2] The chemical conversion film is an organic resin film containing one or more organic resins selected from the group consisting of urethane resin, phenol resin, N-methylglucamine resin, tannic acid and polyacrylic acid. The complex according to [1].
[3] The chemical conversion film includes one or more organic resins selected from the group consisting of urethane resin, phenol resin, N-methylglucamine resin, tannic acid and polyacrylic acid, silane compound, titanium [1] The composite according to [1], which is an organic-inorganic composite film containing one or more inorganic compounds selected from the group consisting of a compound, a fluorine compound and a zirconium compound.

Moreover, this invention relates to the manufacturing method of the following composites.
[4] A method for producing a composite in which a coated stainless steel plate and a molded body of a polycarbonate resin composition are joined: a step of preparing a coated stainless steel plate and inserting the coated stainless steel plate into an injection mold And a step of injecting a polycarbonate resin composition into the injection mold and joining a molded body of the polycarbonate resin composition to the surface of the coated stainless steel plate; And a chemical conversion treatment film containing an organic resin formed on the surface of the stainless steel plate, an undercoat film formed on the chemical conversion treatment film, and a topcoat film formed on the undercoat film. The undercoating film is a cured product of a self-crosslinking epoxy resin composition containing a phenoxy resin or an epoxy resin, a phenoxy resin, or A cured product of an epoxy resin composition containing a poxy resin and a curing agent, or a cured product of a polyester resin composition containing a crosslinkable functional group-containing polyester resin and isocyanate; From the hardened | cured material of the polyester-type resin composition which contains the polyester resin and isocyanate containing a crosslinkable functional group with an average molecular weight of 10,000-30000, and whose mass ratio of the said polyester resin and the said isocyanate is 70: 30-95: 5 The total film thickness of the undercoat film and the topcoat film is 20 μm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the composite_body | complex which is excellent in the adhesiveness of a coated stainless steel plate and the molded object of a polycarbonate resin composition, and can be manufactured efficiently by a precoat system can be provided.

It is a schematic diagram of the punching process of a coated stainless steel plate. It is a graph which shows the relationship between the total film thickness of a coating film, and the floating width of a coating film. It is a figure which shows the composite_body | complex with which the coated stainless steel plate and the molded object of polycarbonate resin were joined.

1. Composite The composite of the present invention is a composite in which a coated stainless steel plate and a molded body of a polycarbonate resin composition are joined. One feature of the composite of the present invention is that a chemical conversion treatment film, an undercoat film and an overcoat film are formed on the surface of a stainless steel plate.

  Hereinafter, each element of the composite of the present invention will be described.

(1) Coated stainless steel plate The composite of the present invention uses a coated stainless steel plate having a chemical conversion treatment film, an undercoat film, and a topcoat film as a metal plate.

A) Stainless steel plate In the present invention, a stainless steel plate is used as the metal plate in order to achieve the strength and corrosion resistance required in various applications. Although the kind of stainless steel plate is not particularly limited, it is preferable that the Vickers hardness measured in accordance with JIS Z2244 is in the range of HV250 to HV530. By using such a stainless steel plate, it is possible to ensure the strength required for electronic equipment and the like while reducing the plate thickness. When an aluminum plate, a magnesium alloy plate, or the like is used, it is necessary to increase the plate thickness in order to ensure sufficient strength, and it is difficult to apply to electronic devices. Examples of suitable stainless steel grades include SUS301-CSP EH, SUS304-CSP 1 / 2H, etc. according to JIS G4313. The components and metal structure of the stainless steel plate are not particularly limited, and steels having an arbitrary composition can be used in a metal structure such as austenite, martensite, ferrite, and ferrite / martensite two-phase.

  A plating layer may be formed on the surface of the stainless steel plate. That is, the stainless steel plate may be a plated stainless steel plate. For example, after forming a nickel plating layer or a copper plating layer on both surfaces of a stainless steel plate, a coating film (a chemical conversion film, an undercoat film, and an overcoat film) described later may be formed only on one surface. Thereby, the adhesiveness of a polycarbonate resin composition can be improved in the surface in which the coating film was formed, and electroconductivity can be provided in the surface in which the coating film was not formed.

  The plate | board thickness of a stainless steel plate is not specifically limited, According to a use, it can set suitably. For example, when the composite of the present invention is applied to an electronic device such as a mobile phone, the thickness of the stainless steel plate is about 0.2 to 0.5 mm.

B) Chemical conversion treatment film The chemical conversion treatment film is formed on the surface of the stainless steel plate, and improves the adhesion between the stainless steel plate and the undercoat film. Although the chemical conversion treatment film should just be formed in the area | region (joint surface) joined to the molded object of a polycarbonate resin composition among the surfaces of a stainless steel plate, it is normally formed in the whole surface of a stainless steel plate.

  The type of the chemical conversion coating is not particularly limited as long as the adhesion between the stainless steel plate and the undercoat coating can be improved. For example, the chemical conversion film is the following organic resin film or organic-inorganic composite film.

[Organic resin film]
The organic resin film is a film mainly made of an organic resin. Although the kind of organic resin which comprises an organic resin film is not specifically limited, From a viewpoint of workability (flexibility) and adhesiveness, urethane resin, phenol resin, N-methylglucamine resin, tannic acid, or polyacrylic acid It is preferable that These organic resins may be used alone or in combination of two or more.

[Organic-inorganic composite coating]
The organic-inorganic composite film is a film further containing an inorganic compound in addition to the organic resin. By mix | blending an inorganic compound, the adhesiveness of the chemical conversion treatment film (organic-inorganic composite film) with respect to a stainless steel plate can further be improved.

  The type of organic resin constituting the organic-inorganic composite film is not particularly limited, but for the same reason as the organic resin film, it may be urethane resin, phenol resin, N-methylglucamine resin, tannic acid or polyacrylic acid. preferable. These organic resins may be used alone or in combination of two or more.

  The kind of the inorganic compound is not particularly limited as long as the adhesion of the chemical conversion coating (organic-inorganic composite coating) can be improved. Examples of the inorganic compound include a silane compound, a titanium compound, a fluorine compound, or a zirconium compound. These inorganic compounds may be used alone or in combination of two or more.

  The silane compound is bonded to the stainless steel plate and the organic resin to improve the adhesion of the organic-inorganic composite film to the stainless steel plate. Examples of the silane compound include alkyl silane, alkoxy silane, epoxy silane, amino silane and the like. The amount of the silane compound in the organic-inorganic composite film is preferably in the range of 30 to 60% by mass. When content of a silane compound is less than 30 mass%, the effect by adding a silane compound cannot fully be improved. On the other hand, when the content of the silane compound exceeds 60% by mass, the effect of improving the adhesion is saturated and no further improvement is observed.

The titanium compound is bonded to the stainless steel plate and the organic resin through oxygen, and improves the adhesion of the organic-inorganic composite film to the stainless steel plate. Examples of titanium compounds include KnTiF ₆ (K: alkali metal or alkaline earth metal, n: 1 or 2), K ₂ [TiO (COO) ₂ ], (NH ₄ ) ₂ TiF ₆ , H ₂ TiF ₆ , TiCl ₄ , TiOSO ₄ , Ti (SO ₄ ) ₂ , Ti (OH) _{4 and the} like are included. The amount of the titanium compound in the organic-inorganic composite film is preferably in the range of ² to 50 mg / m ^{2 in} terms of Ti equivalent adhesion amount. When the amount of Ti-equivalent adhesion is less than 2 mg / m ^{2, the} effect of adding the titanium compound cannot be sufficiently improved. On the other hand, when the adhesion amount in terms of Ti exceeds 50 mg / m ² , the effect of improving the adhesion is saturated and no further improvement is observed.

The fluorine compound improves the adhesion of the organic-inorganic composite film to the stainless steel plate by etching the surface of the stainless steel plate (effect of fluoride ions) and activating the surface of the stainless steel plate. Examples of the fluorine compound include (NH ₄ ) ₂ TiF ₆ , H ₂ TiF ₆ , KnTiF _{6 and the} like. The amount of the fluorine compound in the organic-inorganic composite film is preferably in the range of 7 to 50 mg / m ^{2 in} terms of F-equivalent adhesion. When the F conversion adhesion amount is less than 7 mg / m ^{2, the} effect of adding the fluorine compound cannot be sufficiently improved. On the other hand, when the F conversion adhesion amount is more than 50 mg / m ² , a large amount of metal is eluted in the organic-inorganic composite coating, and the strength of the organic-inorganic composite coating may be weakened.

Similar to the titanium compound, the zirconium compound is bonded to the stainless steel plate and the organic resin through oxygen to improve the adhesion of the organic-inorganic composite film to the stainless steel plate. Examples of the zirconium compound include zirconates such as zirconium oxide and sodium zirconate, and fluorinated zirconates such as fluorinated zirconium acid and sodium fluorinated zirconate. The amount of the zirconium compound in the organic-inorganic composite film is preferably in the range of 5 to 50 mg / m ^{2 in} terms of Zr equivalent adhesion. When the amount of adhesion in terms of Zr is less than 5 mg / m ^{2, the} effect of adding the zirconium compound cannot be sufficiently improved. On the other hand, when the adhesion amount in terms of Zr exceeds 50 mg / m ² , the effect of improving the adhesion is saturated, and no further improvement is observed.

The film thickness of a chemical conversion treatment film will not be specifically limited if the adhesiveness of a stainless steel plate and an undercoat coating film can be ensured. For example, in the case of the above-mentioned organic-inorganic composite film, the total of the Ti conversion deposit and the Zr conversion deposit is preferably in the range of ² to 50 mg / m ² and more preferably in the range of ^{2 to} 30 mg / m ^2. preferable.

C) Undercoat film The undercoat film is formed on the chemical conversion film. The undercoat film improves the adhesion of the topcoat film to the stainless steel plate together with the chemical conversion film. Similar to the chemical conversion coating, the undercoat coating film may be formed on the joining surface of the stainless steel plate surface, but is usually formed on the entire surface of the stainless steel plate.

  The undercoat coating is a coating made of a cured product of a self-crosslinking epoxy resin composition, a coating made of a cured product of a non-self-crosslinking epoxy resin composition, or a cured product of a polyester resin composition. It is a coating film.

  When the undercoat coating film is a coating film formed of a cured product of a self-crosslinking epoxy resin composition, the epoxy resin composition contains a self-crosslinking phenoxy resin or a self-crosslinking epoxy resin. The self-crosslinking resin has a blocked reactive (crosslinkable) functional group (for example, an isocyanate group) and another functional group that can react with the reactive functional group (for example, a hydroxy group). ing. When the reactive functional group reacts with another functional group during baking of the paint, a cured product of the resin composition is formed.

  When the undercoat coating film is a coating film made of a cured product of a non-self-crosslinking type epoxy resin composition, the epoxy resin composition includes a phenoxy resin or an epoxy resin and a curing agent. The kind of hardening | curing agent is not specifically limited, For example, they are a polyamine, an acid anhydride, etc.

  In the case where the undercoat coating film is a coating film made of a cured product of a polyester resin composition, the polyester resin composition contains a polyester resin and an isocyanate (curing agent).

  The polyester resin used as the main resin is a polyester resin having a crosslinkable functional group. Examples of the crosslinkable functional group include a hydroxy group, a carboxy group, and an alkoxysilane group. The polyester resin preferably has two or more of these crosslinkable functional groups per molecule.

  The number average molecular weight of the polyester resin is not particularly limited, but is preferably in the range of 8000 to 40000 from the viewpoint of workability. When the number average molecular weight is less than 8000, the crosslink density between molecules becomes too high, and the processability is lowered. On the other hand, when the number average molecular weight is more than 40,000, the viscosity becomes large and it is difficult to prepare a paint.

  The type of isocyanate used as the curing agent is not particularly limited, but a blocked isocyanate compound in which an isocyanate group is blocked with a blocking agent is preferable from the viewpoint of the pot life of the paint. Examples of isocyanate compounds include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, aliphatic diisocyanates such as hexamethylene diisocyanate and dimer acid diisocyanate, alicyclics such as isophorone diisocyanate and cyclohexane diisocyanate. Diisocyanates, burette type adducts or isocyanuric ring type adducts of these isocyanates are included. These isocyanates may be used alone or in combination of two or more. Examples of the blocking agent include phenols, oximes, active methylenes, ε-caprolactams, triazoles, pyrazoles and the like.

  The amount of isocyanate is preferably in the range of 5 to 30% by mass when the total amount of the polyester resin and isocyanate is 100% by mass. When the isocyanate is less than 5% by mass, the cross-linking density between molecules becomes too small, and there is a risk that cohesive failure occurs due to shear stress during molding. Moreover, when isocyanate exceeds 30 mass%, the crosslink density between molecules will become large too much and workability will fall.

  The film thickness of the undercoat film is not particularly limited as long as the total film thickness of the undercoat film and the topcoat film is 20 μm or less, as will be described later. For example, the film thickness of the undercoat coating film is 3 μm or more. When the film thickness of an undercoat coating film is less than 3 micrometers, there exists a possibility that the adhesiveness of the topcoat film with respect to a stainless steel plate cannot fully be improved.

D) Top coat film The top coat film is made of a cured product of a polyester resin composition containing a polyester resin and an isocyanate. The top coat film improves the adhesion of the molded article of the polycarbonate resin composition to the stainless steel plate. The top coat film may be formed on the joining surface of the stainless steel plate surface as in the case of the chemical conversion treatment film and the undercoat film, but is usually formed on the entire surface of the stainless steel plate.

  The polyester resin used as the main resin is a polyester resin having a crosslinkable functional group. Examples of the crosslinkable functional group include a hydroxy group, a carboxy group, and an alkoxysilane group. The polyester resin preferably has two or more of these crosslinkable functional groups per molecule.

  The number average molecular weight of the polyester resin is preferably in the range of 10,000 to 30,000. When the number average molecular weight is less than 10,000, the crosslink density is high and the compatibility with the polycarbonate resin composition is lowered, so that the adhesion may be lowered. On the other hand, when the number average molecular weight is more than 30000, the crosslinking density is low, and burrs may occur during insert molding. Moreover, if it is in the said range, the workability of a coating film is ensured.

  The kind of isocyanate used as the curing agent is not particularly limited, and for example, those described above can be used.

  It is preferable that the compounding quantity of isocyanate is 5-30 mass% when the sum total of a polyester resin and isocyanate is 100 mass%. When the isocyanate is less than 5% by mass, the cross-linking density between molecules becomes too small, and there is a risk that cohesive failure occurs due to shear stress during molding. On the other hand, when the isocyanate is more than 30% by mass, the cross-linking density between molecules becomes too large, and the processability is lowered.

  The glass transition point of the top coat film is preferably in the range of 50 to 150 ° C. When the glass transition point is less than 50 ° C., the adhesion of the molded article of the polycarbonate resin composition to the stainless steel plate may be lowered at room temperature. On the other hand, when the glass transition point is higher than 150 ° C., the molded article of the polycarbonate resin composition may not be bonded at the time of insert molding.

  The film thickness of the top coat film is not particularly limited as long as the total film thickness of the undercoat film and the top coat film is 20 μm or less, as will be described later. For example, the film thickness of the top coat film is about 3 to 15 μm. When the film thickness of a top coat film is less than 3 micrometers, there exists a possibility that the adhesiveness of the molded object of the polycarbonate resin composition with respect to a stainless steel plate cannot fully be improved. On the other hand, when the film thickness of the top coating film is more than 15 μm, the coating film may be peeled off during molding (for example, pressing).

  The coated stainless steel plate contained in the composite of the present invention can be manufactured by a precoat method. For that purpose, the total film thickness of the undercoat film and the topcoat film is preferably 20 μm or less, more preferably 15 μm or less, and particularly preferably 10 μm or less. When the total film thickness exceeds 20 μm, the coating film may be peeled off during forming (for example, pressing), making it difficult to use the coated stainless steel sheet as a precoated steel sheet.

(2) Molded body of polycarbonate resin composition The molded body of the polycarbonate resin composition is bonded to the surface of the above-mentioned coated stainless steel sheet (more precisely, the surface of the top coat film). The shape of the molded article of the polycarbonate resin composition is not particularly limited, and can be appropriately selected depending on the application.

  The polycarbonate resin composition may contain various additives in addition to the polycarbonate as the main resin. For example, the polycarbonate resin composition may contain various fillers in order to adjust the molding shrinkage rate and material strength. Examples of fillers include fiber fillers such as glass fiber, carbon fiber, and aramid resin; carbon black, calcium carbonate, calcium silicate, magnesium carbonate, silica, talc, glass, clay, lignin, mica, quartz powder, glass sphere Powder fillers such as: pulverized carbon fiber or aramid fiber. Although the compounding quantity of a filler is not specifically limited, The inside of the range of 5-60 mass% is preferable, and the inside of the range of 10-40 mass% is more preferable.

  As mentioned above, since the chemical conversion treatment film and the predetermined undercoat film are formed on the surface of the stainless steel plate, the composite of the present invention has high adhesion of the top coat film to the stainless steel plate. Accordingly, when the composite of the present invention is produced, the top coat film does not peel off even if a molding process (for example, press work) is performed after the top coat film is formed. That is, the composite (coated stainless steel plate) of the present invention can be manufactured by a precoat method.

  In addition, the composite of the present invention is excellent in adhesion between the stainless steel plate and the molded article of the polycarbonate resin composition because a predetermined top coat film having excellent adhesion to the undercoat film and the polycarbonate resin composition is formed. ing.

  The method for producing the composite of the present invention is not particularly limited. For example, the composite of the present invention can be produced by the following procedure.

2. Manufacturing method of composite body The manufacturing method of the composite body of the present invention includes 1) a first step of preparing a coated stainless steel plate, 2) a second step of inserting the coated stainless steel plate into an injection mold, and 3). And a third step of joining a molded body of the polycarbonate resin composition to the surface of the coated stainless steel plate.

  Hereinafter, each process of the present invention will be described.

1) 1st process In the 1st process, the above-mentioned coated stainless steel plate is prepared. For example, the above-mentioned coated stainless steel sheet may be produced by sequentially forming a chemical conversion film, an undercoat film, and a topcoat film on the surface of a stainless steel sheet.

  The chemical conversion treatment film can be formed by applying a chemical conversion treatment solution to the surface of a stainless steel plate and drying it. The method for applying the chemical conversion liquid is not particularly limited, and may be appropriately selected from known methods. Examples of such a coating method include a roll coating method, a curtain flow method, a spin coating method, a spray method, and a dip pulling method. What is necessary is just to set suitably the drying conditions of a chemical conversion liquid according to the composition of a chemical conversion liquid, etc. For example, a stainless steel plate coated with a chemical conversion treatment solution is placed in a drying oven without being washed with water, and heated so that the ultimate plate temperature is in the range of 80 to 250 ° C. A treatment film can be formed.

  The undercoat coating is applied by baking the above-mentioned self-crosslinking epoxy resin composition, non-self-crosslinking epoxy resin composition, or polyester resin composition on the chemical conversion coating film, and baking. Can be formed. The method for applying the undercoat paint is not particularly limited, and may be appropriately selected from known methods. Examples of such a coating method include a roll coating method, a curtain flow method, a spin coating method, a spray method, and a dip pulling method. The baking condition of the undercoat paint may be appropriately set according to the composition of the undercoat paint. For example, a chemical conversion treated stainless steel plate coated with a primer coating is put into a drying oven and heated so that the ultimate plate temperature is in the range of 160 to 230 ° C., thereby providing a uniform primer coating on the chemical conversion coating. Can be formed.

  The top coat film can be formed by applying and baking a top coat paint containing the above-mentioned polyester resin composition on the undercoat coat film. The method for applying the top coat is not particularly limited, and may be appropriately selected from known methods. Examples of such a coating method include a roll coating method, a curtain flow method, a spin coating method, a spray method, and a dip pulling method. The baking condition of the top coating material may be appropriately set according to the composition of the top coating material. For example, by putting a coated stainless steel plate coated with a top coat into a drying oven and heating it so that the ultimate plate temperature is in the range of 180 to 250 ° C., a uniform top coat is formed on the undercoat. Can be formed.

2) Second Step In the second step, the coated stainless steel plate prepared in the first step is inserted into the injection mold. The coated stainless steel plate may be processed into a desired shape by pressing or the like.

3) Third Step In the third step, a high-temperature polycarbonate resin composition is injected at a high pressure into the injection mold in which the coated stainless steel plate is inserted in the second step. At this time, it is preferable to provide a gas vent in the injection mold so that the polycarbonate resin composition flows smoothly. A high temperature polycarbonate resin composition contacts the top coat film formed on the surface of the coated stainless steel sheet. The temperature of the injection mold is preferably near the melting point of the polycarbonate resin composition.

  After completion of injection, the mold is opened and released to obtain a composite. The composite obtained by injection molding may be annealed after molding to eliminate internal distortion due to molding shrinkage.

  By the above procedure, the molded body of the polycarbonate resin composition can be joined to the surface of the coated stainless steel sheet, and the composite of the present invention can be manufactured.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail with reference to an Example, this invention is not limited by these Examples.

[Example 1]
In Example 1, the influence of the chemical conversion coating on the bending workability and press workability of the coated stainless steel sheet was examined.

1. Preparation of coated stainless steel plate (1) Stainless steel plate A stainless steel plate (SUS304-CSP 1 / 2H) having a thickness of 0.3 mm was prepared as a coating original plate.

(2) Chemical conversion treatment film The surface of the coating original plate was degreased by spraying the surface of the coating original plate with an alkaline degreasing aqueous solution having a liquid temperature of 60 ° C. for 20 seconds and then washing with hot water. Next, the chemical conversion treatment liquid shown in Table 1 is applied to the surface of the degreased coating original plate with a bar coater at room temperature, and heated under conditions of an in-furnace temperature of 50 seconds and an ultimate coating temperature of 100 ° C. to form a chemical conversion treatment film. did. Table 2 shows the type of each component added to the chemical conversion treatment liquid and the concentration of each component in the chemical conversion treatment liquid.

(3) Undercoat coating The surface of the chemical conversion coating was coated with a self-crosslinking phenoxy resin coating having a number average molecular weight of 10,000 at room temperature using a bar coater so that the coating thickness would be 5 μm. Next, the furnace was heated for 50 seconds under the condition of an ultimate material temperature of 200 ° C. to form an undercoat coating film.

(4) Top coating film A polyester resin paint prepared by adding a hydroxyl group-containing polyester resin having a number average molecular weight of 12000 and an isocyanate and having a mass ratio of 85:15 to the surface of the undercoating film The coater was applied at room temperature so that the coating thickness was 5 μm. Next, the coating was heated for 50 seconds under the condition that the material temperature reached 230 ° C. to form a top coat film. By these steps, each coated stainless steel sheet having a total thickness of 10 μm of the undercoat film and the topcoat film was obtained.

2. Evaluation of bending workability The bending workability was evaluated by performing 180 degree bending of each coated stainless steel sheet and by the presence or absence of cracking and peeling of the coating film. Specifically, two plates having the same thickness as the test piece were stacked on the surface of the test piece (50 mm × 40 mm) cut out from each coated stainless steel plate on which the coating film was not formed. Next, the test piece was bent 180 degrees at 25 ° C. so that the coating film was on the outside, and a cellophane tape peeling test was performed on the bent portion. Table 3 shows the evaluation criteria for bending workability, and Table 4 shows the evaluation results for each coated stainless steel sheet.

3. Evaluation of press workability Press workability was evaluated by punching a coated stainless steel plate and using the float width of the coating film. FIG. 1 is a schematic diagram of punching processing of a coated stainless steel sheet. As shown in FIG. 1, punching was performed using a 2000 kN servo press with a clearance of 7% and a punch radius of 0 mm. By observing the cross section after punching, the distance at which the stainless steel plate was peeled from the undercoat film and the topcoat film was defined as the floating width. Table 4 shows the evaluation results of each coated stainless steel sheet.

4). Evaluation of the relationship between the total film thickness of the coating film and the floating width of the coating film About each stainless steel plate produced using the chemical conversion liquid of 1, 8, 17, 18 or 22, it investigated about the relationship between the total film thickness of a base coat film and a top coat film, and the floating width of the paint film after press work It was. The undercoat paint was applied on the chemical conversion coating so that the thickness was 3 to 10 μm. The top coat was applied onto the undercoat so that the thickness was 3 to 20 μm. Through these steps, each coated stainless steel sheet having a total thickness of 6 to 30 μm of the undercoat film and the topcoat film was obtained. The press working is as described above.

5. Results Table 4 shows the evaluation results of bending workability and press workability when the film thickness of the undercoat film and the topcoat film is 5 μm, respectively, and the overall evaluation based on these results. Moreover, the relationship between the total film thickness of a coating film and the floating width of a coating film is shown in FIG.

  As shown in Table 4, no. When the chemical conversion treatment liquid of 18 to 22 was used (when an inorganic film was formed), bending workability was poor and the float width of the coating film was long. On the other hand, no. When the chemical conversion treatment solutions 1 to 7 were used (when an organic resin film was formed), the bending workability was improved and the float width of the coating film was short. In addition, No. containing organic resin and inorganic compound. When the chemical conversion treatment liquids 8 to 17 were used (when the organic-inorganic composite film was formed), the bending workability was further improved and the float width of the coating film was the shortest.

  Further, as shown in FIG. 2, by setting the total film thickness of the undercoat film and the topcoat film to 20 μm or less, the floating width of the coating film could be remarkably suppressed to 30 μm or less (Patent Document 1). (The film thickness is 55 μm or more in the case of the film-laminated metal plate described in 1).

[Example 2]
In Example 2, the adhesion of the molded body of the polycarbonate resin composition to the coated stainless steel plate was examined.

1. Preparation of coated stainless steel plate (1) Stainless steel plate A stainless steel plate (SUS304-CSP 1 / 2H) having a thickness of 0.3 mm was prepared as a coating original plate.

(2) Chemical conversion treatment film The surface of the coating original plate was degreased by spraying the surface of the coating original plate with an alkaline degreasing aqueous solution having a liquid temperature of 60 ° C. for 20 seconds and then washing with hot water. Next, No. 1 shown in Table 1 was applied to the surface of the degreased coated original plate. The chemical conversion treatment solution of 8 or 17 was applied with a bar coater at room temperature, and heated in the in-furnace temperature for 50 seconds under the condition that the ultimate coating temperature was 100 ° C. to form a chemical conversion treatment film.

(3) Undercoat coating film The undercoat paint shown in Table 5 was applied to the surface of the chemical conversion coating film at room temperature with a bar coater so that the coating film thickness was 5 μm. Next, the furnace was heated for 50 seconds under the condition of an ultimate material temperature of 200 ° C. to form an undercoat coating film.

(4) Top coat The top coat containing the hydroxyl group-containing polyester resin and isocyanate (curing agent) shown in Table 6 was applied to the surface of the undercoat at room temperature using a bar coater so that the thickness of the coat was 5 μm. did. Next, the coating was heated for 50 seconds under the condition that the material temperature reached 230 ° C. to form a top coat film. By these steps, each coated stainless steel sheet having a total thickness of 10 μm of the undercoat film and the topcoat film was obtained.

2. Joining molded articles of polycarbonate resin composition (insert molding)
FIG. 3 is a view showing a composite in which a coated stainless steel plate and a polycarbonate (PC) resin are joined. Insert molding was performed using a 15-ton horizontal electric injection molding machine. First, each obtained stainless steel sheet was inserted into an injection mold having a cavity of 60 mm × 20 mm heated to 110 ° C. Subsequently, a polycarbonate resin containing 10% by mass of glass fiber (Iupilon; Mitsubishi Engineering Plastics Co., Ltd.) was injected onto the surface of the top coat film and thermally welded. The size of the joint surface between the top coat film and the polycarbonate resin is 10 mm × 10 mm.

3. Measurement of Shear Bond Strength Shear bond strength was measured by pulling a coated stainless steel plate and a molded article of polycarbonate resin in the same plane direction using a 2-ton autograph. Tables 7 and 8 show the shear bond strength of each composite and its overall evaluation. When the shear bond strength was 80 kgf / cm ² or less, “X” was evaluated, and when the shear bond strength was more than 80 kgf / cm ^2, “◯” was evaluated.

4). Results From Table 7 and Table 8, the number average molecular weight of the polyester resin is not in the range of 10,000 to 30,000. In the composites of 55 to 66, the adhesion between the coated stainless steel plate and the molded article of the polycarbonate resin composition was poor. On the other hand, the number average molecular weight is in the range of 10,000 to 30,000. In the composites 1 to 54, the adhesion between the coated stainless steel plate and the molded body of the polycarbonate resin composition was excellent, and exceeded 80 kgf / cm ² which was a guideline for use in a housing member such as an electronic device. .

  Since the composite of the present invention is excellent in adhesion and can be produced by a precoat method, it is useful, for example, as a component of electronic equipment.

Claims (4)

A composite body in which a coated stainless steel plate and a molded body of a polycarbonate resin composition are joined,
The coated stainless steel plate includes a stainless steel plate, a chemical conversion treatment film containing an organic resin formed on the surface of the stainless steel plate, an undercoat film formed on the chemical conversion treatment film, and the undercoat film. Having a formed top coat film,
The undercoat coating film is a cured product of a self-crosslinking epoxy resin composition containing a phenoxy resin or an epoxy resin, a cured product of an epoxy resin composition containing a phenoxy resin or an epoxy resin and a curing agent, Or it consists of the hardened | cured material of the polyester-type resin composition containing the polyester resin and isocyanate containing a crosslinkable functional group,
The top coat film comprises a polyester resin containing a crosslinkable functional group having a number average molecular weight of 10,000 to 30,000 and an isocyanate, and the polyester resin and the isocyanate have a mass ratio of 70:30 to 95: 5 It consists of a cured product of a resin composition,
The total film thickness of the undercoat film and the topcoat film is 20 μm or less.
Complex.   The chemical conversion treatment film is an organic resin film containing one or more organic resins selected from the group consisting of urethane resin, phenol resin, N-methylglucamine resin, tannic acid and polyacrylic acid. Item 11. The complex according to Item 1.   The chemical conversion coating is composed of one or more organic resins selected from the group consisting of urethane resin, phenol resin, N-methylglucamine resin, tannic acid and polyacrylic acid, silane compound, titanium compound, fluorine The composite according to claim 1, which is an organic-inorganic composite film containing one or more inorganic compounds selected from the group consisting of a compound and a zirconium compound. A method for producing a composite in which a coated stainless steel plate and a molded article of a polycarbonate resin composition are joined,
Preparing a coated stainless steel sheet;
Inserting the coated stainless steel sheet into an injection mold;
Injecting a polycarbonate resin composition into the injection mold, and bonding a molded body of the polycarbonate resin composition to the surface of the coated stainless steel plate,
The coated stainless steel plate includes a stainless steel plate, a chemical conversion treatment film containing an organic resin formed on the surface of the stainless steel plate, an undercoat film formed on the chemical conversion treatment film, and the undercoat film. Having a formed top coat film,
The undercoat coating film is a cured product of a self-crosslinking epoxy resin composition containing a phenoxy resin or an epoxy resin, a cured product of an epoxy resin composition containing a phenoxy resin or an epoxy resin and a curing agent, Or it consists of the hardened | cured material of the polyester-type resin composition containing the polyester resin and isocyanate containing a crosslinkable functional group,
The top coat film includes a polyester resin containing a crosslinkable functional group having a number average molecular weight of 10,000 to 30,000 and an isocyanate, and the polyester resin and the isocyanate have a mass ratio of 70:30 to 95: 5 It consists of a cured product of a resin composition,
The total film thickness of the undercoat film and the topcoat film is 20 μm or less.
A method for producing a composite.

Images