JP2021126821A - Composite, gasket, method for producing composite, and coated metal plate - Google Patents

Abstract

To provide a composite which can be obtained by a simple method and has good antifreeze resistance and high-temperature sliding resistance.SOLUTION: The composite includes a coated metal plate 110 and a rubber layer 120 joined thereto. The coated metal plate includes a metal plate 111, a chemical conversion coating 112, and a primer layer 113 in this order. The rubber layer is formed of a crosslinked product of a rubber layer coating composition containing a fluorine-containing polymer and a polyol-based crosslinking agent. The primer layer is formed of a cured product of an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2-10 μm. The primer layer has a swelling part on a surface layer part on the rubber layer side, and the surface roughness Ra on the rubber layer side of the primer layer is 0.1-10 μm.SELECTED DRAWING: Figure 1

Description

The present invention relates to composites, gaskets, methods for manufacturing composites and coated metal plates.

As a gasket to be mounted on an engine cylinder head of an automobile or the like, a gasket having a stainless steel plate and a fluorine rubber layer laminated on the stainless steel plate is generally used. A vulcanized adhesive for fluororubber is used to bond the stainless steel plate and the fluororubber layer in such a gasket.

As a vulcanization adhesive for fluororubber, for example, a vulcanization adhesive obtained by diluting a resin composition containing a silane coupling agent with an alcohol solvent is known. In addition, for example, a vulcanized adhesive composition containing (a) a phenol resin or an epoxy resin, (b) a solvent-dispersible silica and a hydrotalcite-related compound, and (c) a fluororubber compound solution or a fluororubber solution ( (Refer to Patent Document 1), and thermosetting phenol resin-based vulcanizing adhesives containing a specific novolak type epoxy resin, a curing accelerator, and silica (see Patent Documents 2 and 3) and the like are known. The vulcanized adhesive layer obtained from such a vulcanized adhesive containing silica is said to have good antifreeze resistance and water resistance.

A gasket using such a vulcanization adhesive is manufactured by the following procedure. First, a vulcanization adhesive is applied onto the stainless steel sheet or its surface-treated layer, and then the solvent component of the vulcanization adhesive is volatilized (dried) to form a vulcanization adhesive layer. Next, a coating composition for a rubber layer in which a fluorine-containing polymer and a cross-linking agent are dissolved is applied to the obtained vulcanization adhesive layer, and the mixture is heated to volatilize the solvent contained in the coating composition while containing fluorine. By cross-linking the polymer, a fluororubber layer is formed on the stainless steel plate.

Japanese Unexamined Patent Publication No. 2011-57986 International Publication No. 2009/122618 Japanese Unexamined Patent Publication No. 2006-218629

By the way, a gasket having a stainless steel plate and a fluororubber layer, which is attached to an automobile engine cylinder head or the like, can 1) maintain the adhesion between the stainless steel plate and the fluororubber even when immersed in an antifreeze solution (hereinafter, "" It is required to be able to maintain the adhesion between the stainless steel sheet and the fluororubber even when sliding under high temperature and high load (hereinafter referred to as “high temperature sliding resistance”).

That is, since the antifreeze liquid easily deteriorates the fluorine rubber layer, the vulcanization adhesive layer, the surface treatment layer of the stainless steel plate, and the like, the antifreeze liquid tends to reduce the adhesion between the stainless steel plate or the vulcanization adhesive layer and the fluorine rubber layer. Therefore, it is desired that the gasket having the stainless steel plate and the fluororubber layer has high resistance to antifreeze (antifreeze resistance). Further, when engine vibration or the like is applied at a high temperature, stress is concentrated on the vulcanization adhesive layer, and it is easy to peel off at that portion, and the adhesion between the vulcanization adhesive layer and the fluorine rubber layer is likely to decrease. Therefore, it is also desired that the gasket having the stainless steel plate and the fluororubber layer have high temperature sliding resistance. As described above, in order to use it as a gasket to be mounted on an engine cylinder head or the like, it is desired to sufficiently improve the adhesion between the fluorine rubber layer and the vulcanization adhesive layer.

Further, in the conventional method for manufacturing a gasket as shown in Patent Documents 1 to 3, a step of applying a vulcanization adhesive on a stainless steel plate is required. Therefore, not only the process tends to be complicated, but also the adhesiveness may vary depending on the coating conditions. Therefore, without applying a vulcanization adhesive, the stainless steel sheet and the fluororubber layer can be obtained by simply applying the coating composition for the rubber layer directly to the stainless steel sheet (which has been subjected to the easy adhesive treatment) and cross-linking. It is also desired to be able to bond.

The present invention has been made in view of the above circumstances, and is a method for producing a composite, gasket, composite, which can be obtained by a simple method and has good antifreeze resistance and high temperature sliding resistance. It is an object of the present invention to provide a painted metal plate.

The present invention relates to the following composites, gaskets, methods for manufacturing composites and coated metal plates.

The composite of the present invention is a composite having a coated metal plate having a metal plate, a chemical conversion coating, and a primer layer in this order, and a rubber layer bonded to the primer layer of the coated metal plate, and the rubber. The layer comprises a crosslinked product of a coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based crosslinking agent, and the primer layer is an epoxy containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm. The primer layer is made of a cured product of the resin composition, has a swollen portion on the surface layer portion on the rubber layer side, and has a surface roughness Ra on the rubber layer side of the primer layer of 0.1 to 10 μm. be.

The gasket of the present invention comprises the composite of the present invention.

The method for producing a composite of the present invention has a metal plate, a chemical conversion coating, and a primer layer in this order, and the primer layer has an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm. A step of preparing a coated metal plate composed of a cured product of the material and having a surface roughness Ra of the primer layer of 0.1 to 10 μm, and a fluorine-containing polymer and a polyol on the primer layer of the coated metal plate. It comprises a step of applying a coating composition for a rubber layer containing a system-crossing agent and then cross-linking to form a rubber layer bonded to the primer layer.

The coated metal plate of the present invention is a coated metal plate for joining with a rubber layer composed of a crosslinked product of a coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based cross-linking agent, and is a metal plate and a chemical conversion treatment. The primer layer has a film and a primer layer in this order, and the primer layer is arranged on the outermost layer of the coated metal plate, and cures an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm. The primer layer is made of a material and has a surface roughness Ra of 0.1 to 10 μm.

According to the present invention, it is possible to provide a composite, a gasket, a method for manufacturing the composite, and a coated metal plate which can be obtained by a simple method and have good antifreeze resistance and high temperature sliding resistance. ..

FIG. 1A is a schematic cross-sectional view showing an example of the composite of the present invention, and FIG. 1B is a partially enlarged schematic cross-sectional view of FIG. 1A.

The present inventors satisfactorily joined the metal plate and the rubber layer only by directly applying the coating composition for the rubber layer and cross-linking without applying the vulcanization adhesive as in the conventional case. The method for producing the complex was examined.

Then, the present inventors include silica particles having a large particle size in the primer layer so that the surface roughness Ra of the primer layer of the coated metal plate (which becomes the bonding surface with the rubber layer) is within a predetermined range. It has been found that the adhesiveness between the primer layer and the rubber layer can be well maintained even when the primer layer and the rubber layer are slid while being immersed in an antifreeze solution or when a load is applied to the joint surface at a high temperature.

The reason for this is not clear, but it is speculated as follows. That is, by incorporating silica particles in the primer layer, irregularities can be formed on the surface of the primer layer, so that an anchor effect with the rubber layer can be easily obtained. Therefore, it is considered that good adhesiveness can be maintained between the primer layer and the rubber layer even when immersed in an antifreeze solution.

Further, the rubber layer is formed by volatilizing the solvent and cross-linking the fluorine-containing polymer from the coating film of the coating composition for the rubber layer in which the fluorine-containing polymer and the polyol-based cross-linking agent are dispersed or dissolved in the solvent. It is formed. Here, the surface layer portion of the primer layer to which the coating composition for the rubber layer is applied is swollen by the permeation of the solvent or the like contained in the coating composition. Since the swelling portion of such a primer layer has a relatively low coating film cohesive force, the coating film cohesive force cannot be maintained under high temperature sliding, and when vibration is applied at high temperature, the primer layer and the rubber layer become Peeling is likely to occur due to the cohesive failure of the interface or the primer layer. On the other hand, by appropriately increasing the particle size of the silica particles contained in the primer layer, the coating film cohesive force of the primer layer (particularly the swollen portion) can be effectively increased. As a result, even if vibration is applied at a high temperature, the coating film cohesive force of the primer layer (particularly the swollen portion) near the interface with the rubber layer can be maintained, which is good between the primer layer and the rubber layer. It is considered that the adhesiveness can be maintained.

Further, since the polyol-based cross-linking agent (for example, bisphenol AF) constituting the rubber layer has a high affinity with the epoxy resin (for example, bisphenol type epoxy resin) constituting the primer layer, it is between the primer layer and the rubber layer. It is considered that good adhesiveness can be maintained.

Further, by arranging the chemical conversion treatment film between the metal plate and the primer layer, it is possible to prevent the adhesion between the metal plate and the primer layer from being impaired even if silica particles having a large particle size are contained.

That is, the composite of the present invention simply applies the coating composition for a rubber layer directly on (the primer layer) of the coated metal plate and crosslinks the composite without applying a vulcanization adhesive as in the conventional case. Can be obtained at. Further, the coated metal plate used for producing the composite can exhibit good adhesiveness even if the primer layer does not contain a rubber component or the like. Therefore, even when the coated metal plate is wound into a coil, it is possible to prevent the primer layers from fusing (hereinafter, referred to as "blocking"). The present invention has been made based on such findings.

Hereinafter, embodiments of the present invention will be described in detail.

1. 1. Composite The composite of the present invention has a coated metal plate and a rubber layer bonded to a primer layer of the coated metal plate.

1-1. Painted metal plate The painted metal plate has a metal plate, a chemical conversion coating, and a primer layer in this order.

[Metal plate]
Examples of metal plates include steel sheets (including cold-rolled steel sheets, hot-rolled steel sheets, and their annealed sheets), stainless steel sheets, or plated steel sheets obtained by plating these steel sheets, aluminum plates, aluminum alloy plates, and copper plates. Metal plate is included. Among them, cold-rolled steel sheets, stainless steel sheets, and plated steel sheets are preferable from the viewpoint of having good heat resistance and strength, and stainless steel sheets and plated steel sheets are particularly preferable from the viewpoint of having high heat resistance.

The stainless steel plate is not particularly limited, and may be any of austenitic, martensitic, ferrite, and ferrite / martensitic two-phase systems. Examples of stainless steel sheets include stainless steel sheets for springs such as SUS301H-CSP and SUS410.

A plated steel sheet is one in which the surface of the steel sheet is coated with a plating layer containing a metal other than iron. Examples of metals other than iron that make up the plating layer include zinc, aluminum, magnesium, and alloys of these metals. Examples of the plated steel sheet include a galvanized steel sheet, a Zn-Al alloy plated steel sheet, a Zn-Al-Mg alloy plated steel sheet, an aluminum plated steel sheet and the like.

If necessary, the metal plate may be subjected to known pre-painting treatment such as degreasing treatment, surface cleaning by corona discharge, or roughening by mechanical polishing, pickling, shot blasting, or the like.

The thickness of the metal plate can be appropriately set according to the application, but when used for a gasket for an engine cylinder head, it can be, for example, 0.1 to 0.4 mm.

[Chemical conversion coating]
The chemical conversion treatment film is formed between the metal plate and the primer layer, and improves the adhesion between the metal plate and the primer layer. The chemical conversion treatment film may be formed on at least the region (joint surface) of the surface of the metal plate to be joined with the rubber layer, but may be formed on the entire surface of the metal plate.

The type of the chemical conversion treatment film is not particularly limited, and may be a chromate film such as a chromate-based or chromium phosphate-based film, or a chromate-free film. For example, from the viewpoint of reducing the environmental load, the chemical conversion coating is preferably a chromate-free coating.

The chromate-free film contains an inorganic compound containing no chromate and an organic resin.

The inorganic compound is selected from the group consisting of a titanium compound (for example, Ti-Mo composite material), a fluoroacid compound (for example, hexafluorotitanic acid), a zirconium compound (for example, hexafluorozirric acid), and a silane coupling agent. These inorganic compounds may be used alone or in combination of two or more. Above all, the inorganic compound is preferably a silane coupling agent from the viewpoint of easily improving the adhesion between the metal plate and the primer layer.

The silane coupling agent is not particularly limited, but preferably has an amino group, preferably a primary amino group. When the organic resin further contains an isocyanate compound or a polycarbodiimide compound, the silane coupling agent having a primary amino group is crosslinked with the isocyanate compound or the polycarbodiimide compound to form a dense chemical conversion treatment film having a high barrier property. Because it can be done.

Examples of silane coupling agents include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropyltrimethoxysilane, N- (2-aminoethyl) aminopropylmethyl. Dimethoxysilane, N- (2-aminoethyl) aminopropyltriethoxysilane, N- (2-aminoethyl) aminopropylmethyldiethoxysilane, N- (2-aminoethyl) aminopropylmethyldimethoxysilane and the like are included.

The type of the organic resin is not particularly limited, but may be a resin such as a urethane resin or a phenol resin. Since these resins have polar groups, it is easy to improve the adhesion to the metal plate. These organic resins may be used alone or in combination of two or more. Further, these organic resins may be cured with a curing agent such as an isocyanate compound or a polycarbodiimide compound.

The amount of the chemical conversion coating adhered is not particularly limited as long as it can improve the adhesion between the metal plate and the primer layer. For example, in the case of a chromate film, the total Cr equivalent adhesion amount is preferably 5 to 100 mg / m ² . Also, chromate-free case of the coating, the coating comprising a titanium compound all Ti equivalent coating weight of 1 to 100 mg / ^{m 2,} the fluoro acid based coating fluorine equivalent coating weight or total metal element equivalent coating weight of 3 to 100 mg / ^{m 2} In the film containing the silane coupling agent, the adhesion amount of the silane coupling agent is preferably ^{, for example, 3 to 200 mg / m 2.}

[Primer layer]
The primer layer is on the chemical conversion treatment film and is arranged on the outermost layer of the coated metal plate, and adheres (or joins) the metal plate and the rubber layer. The primer layer is preferably composed of a cured product of a resin composition containing a curable resin, a curing agent, and an inorganic aggregate from the viewpoint of enhancing the adhesiveness (or bondability) between the metal plate and the rubber layer.

(Curable resin)
The curable resin is not particularly limited as long as it has good adhesion to the chemical conversion treatment film. Above all, from the viewpoint that good adhesion without peeling of the coating film during molding is easily obtained, or when the chemical conversion coating contains a silane coupling agent having an amino group, good adhesion with the chemical conversion coating can be obtained. The curable resin is preferably an epoxy resin from the viewpoint of easy susceptibility.

That is, the primer layer is preferably composed of a cured product of an epoxy resin composition containing an epoxy resin, a curing agent, and an inorganic aggregate.

The number average molecular weight of the epoxy resin is not particularly limited, but is preferably about several thousand from the viewpoint of the strength and processability of the coating film. Specifically, the number average molecular weight of the epoxy resin is preferably 2000 to 8000. When the number average molecular weight of the epoxy resin is 2000 or more, it is easy to obtain a coating film having good strength, and it is easy to improve corrosion resistance and the like. When the number average molecular weight of the epoxy resin is 8000 or less, the viscosity of the coating liquid does not become too high, so that the coating workability and workability by a roll coater or the like are not easily impaired. Moreover, since the ratio of the solid content in the paint does not decrease too much, the productivity is not easily impaired. From the above viewpoint, the number average molecular weight of the epoxy resin is more preferably 3000 to 7000. The number average molecular weight of the epoxy resin can be measured in terms of polystyrene by a gel permeation chromatography method. The specific measurement conditions may be the same as in the examples described later.

The epoxy resin is not particularly limited, and may be an aliphatic epoxy resin, an alicyclic epoxy resin, or an aromatic epoxy resin. Among them, an alicyclic epoxy resin or an aromatic epoxy resin is preferable from the viewpoint of having good heat resistance. Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, and hydride bisphenol A type epoxy resins. Among them, an aromatic epoxy resin is preferable, and a bisphenol type epoxy resin is more preferable, from the viewpoints of adhesion to a metal plate (having a chemical conversion film), coating cohesiveness of a primer layer, heat resistance, and the like. , Bisphenol A type epoxy resin is more preferable.

Further, the epoxy resin may be a modified epoxy resin having a functional group that reacts with an isocyanate group such as an amino group or a hydroxy group (for example, an epoxy resin modified with an alkanolamine). Above all, the epoxy resin is a modified epoxy resin having a functional group that reacts with an isocyanate group from the viewpoint of enhancing the affinity with the components contained in the chemical conversion treatment film and the rubber layer and facilitating the acquisition of good adhesion. Is preferable.

The content of the epoxy resin is preferably 55 to 94% by mass with respect to the solid content of the epoxy resin composition. When the content of the epoxy resin is 55% by mass or more, the obtained primer layer can not only have sufficient coating film cohesive force, but also has good scratch resistance, corrosion resistance, water resistance, chemical resistance, and the like. Can have. When the content of the epoxy resin is 94% by mass or less, the viscosity of the epoxy resin composition when forming the primer layer does not become too high, so that the coating workability and workability are not easily impaired. From the above viewpoint, the content of the epoxy resin is more preferably 65 to 87% by mass with respect to the solid content of the epoxy resin composition.

(Hardener)
The curing agent is not particularly limited as long as it can cure the curable resin. Examples of curing agents for curing epoxy resins include amine compounds, acid anhydrides and imidazole compounds. Further, when the epoxy resin is a modified epoxy resin having a functional group that reacts with the isocyanate group as described above, an isocyanate compound can also be used as a curing agent. Above all, the isocyanate compound is preferable from the viewpoint of enhancing the affinity with the components contained in the chemical conversion treatment film and the rubber layer and facilitating good adhesion even in the processed portion.

Examples of isocyanate compounds include aliphatic isocyanate compounds such as hexamethylene diisocyanate (HDI) and lysine diisocyanate; alicyclic isocyanate compounds such as isophorone diisocyanate (IPDI), cyclohexanediisocyanate and dicyclohexylmethane diisocyanate; methylenediphenyldiisocyanate (MDI), Aromatic isocyanate compounds such as tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), naphthylene 1,5-diisocyanate (NDI), tetramethylene xylylene diisocyanate (TMXDI), and phenylenedi isocyanate are included.

Further, these curing agents may be a curing agent having an aromatic ring (aromatic curing agent) or a curing agent having no aromatic ring (aliphatic curing agent). Above all, an aromatic curing agent is preferable from the viewpoint of easily increasing the heat resistance of the primer layer.

That is, from the viewpoint of obtaining a primer layer having good adhesion and heat resistance, the curing agent is preferably an aromatic isocyanate compound.

The content of the curing agent is preferably 5 to 50% by mass with respect to the epoxy resin. When the content of the curing agent is 5% by mass or more, the epoxy resin can be sufficiently cured. As a result, a primer layer having sufficient coating film cohesive force can be easily obtained, and adhesiveness (or bondability) between the primer layer and the rubber layer can be easily obtained. When the content of the curing agent is 50% by mass or less, the primer layer is not excessively cured, and the processability of the primer layer can be easily obtained. From the above viewpoint, the content of the curing agent is more preferably 10 to 30% by mass with respect to the epoxy resin.

(Inorganic aggregate)
The inorganic aggregate enhances the film hardness of the primer layer to enhance the high temperature sliding resistance, and imparts unevenness to the surface of the primer layer to enhance the adhesion to the rubber layer. The inorganic aggregate may be any granular or lumpy inorganic aggregate, and is not particularly limited, and examples thereof include titania particles and silica particles. Among them, silica particles are preferable from the viewpoints that the strength of the primer layer can be easily increased and the cost is low.

The average particle size of the silica particles may be set so that the surface roughness Ra of the primer layer is in the range described later, and may be, for example, 2 to 10 μm. For example, when the thickness of the primer layer is 7 μm or less and the average particle size of the silica particles exceeds 10 μm, the silica particles are likely to fall off, so that the adhesion is likely to be extremely lowered. On the other hand, when the average particle size of the silica particles is within the above range, not only the surface roughness Ra of the primer layer can be adjusted to the range described later, but also the silica particles are less likely to fall off. Further, when the average particle size of the silica particles is less than 2 μm, it is difficult to sufficiently obtain the coating film cohesive force of the primer layer, so that the high temperature slidability tends to decrease. Further, the surface roughness Ra of the primer layer is unlikely to fall within the range described later, and the adhesion between the primer layer and the rubber layer is also difficult to obtain. From these viewpoints, the average particle size of the silica particles is more preferably 3 to 7 μm.

The content of the silica particles may be set so that the surface roughness Ra of the primer layer is in the range described later, and is preferably 1 to 20% by mass with respect to the epoxy resin. When the content of the silica particles is 1% by mass or more, not only the surface roughness Ra of the primer layer is easily increased to improve the adhesion to the rubber layer, but also the cohesive force of the coating film is easily increased, so that it has high temperature sliding resistance. Is also easy to raise. When the content of the silica particles is 20% by mass or less, the primer layer is less likely to undergo agglutination fracture when processing a metal plate, for example, and the processability and adhesiveness are less likely to be impaired. From the above viewpoint, the content of the silica particles is more preferably 5 to 20% by mass with respect to the epoxy resin.

(Layer state)
The primer layer has a swollen portion on the surface layer portion on the rubber layer side. The swollen portion includes a solvent component contained in the coating composition when the coating composition for a rubber layer is applied onto the primer layer of the coated metal plate in the composite manufacturing step (step (2)) described later. Is formed by penetrating into the primer layer.

The swollen portion is preferably formed only on the surface layer portion on the rubber layer side of the thickness direction of the primer layer from the viewpoint of not impairing the adhesion between the metal plate (or chemical conversion treatment film) and the primer layer. .. The thickness of the swollen portion is preferably about 1 to 90% of the thickness of the primer layer. Whether or not there is a swollen portion can be confirmed by, for example, low vacuum SEM observation of the cross section of the primer layer.

(Physical characteristics)
The surface roughness Ra of the primer layer (surface roughness Ra on the rubber layer side) is preferably 0.1 to 10 μm. When the surface roughness Ra of the primer layer is 0.1 μm or more, not only the anchor effect is easily obtained, but also the high temperature slidability is likely to be enhanced, so that interfacial peeling with the rubber layer is unlikely to occur, which is good. Adhesion is easy to obtain. When the surface roughness Ra of the primer layer is 10 μm or less, not only is it difficult for silica particles to fall off from the primer layer, but also the proportion of the resin component is not too small, so that the adhesion to the rubber layer is not easily impaired. .. The surface roughness Ra of the primer layer is more preferably 0.5 to 3 μm.

The surface roughness Ra of the primer layer can be measured as an arithmetic mean roughness according to JIS B0601-2001. Specifically, the surface roughness Ra (arithmetic mean roughness) of the surface of the primer layer is measured with a contact roughness meter.

The surface roughness Ra of the primer layer can be adjusted by, for example, the content of silica particles and the average particle size. In order to keep the surface roughness Ra of the primer layer above a certain level, it is preferable that, for example, the content of silica particles and the average particle size are both above a certain level.

The thickness of the primer layer is not particularly limited, but may be, for example, 3 to 7 μm. When the thickness of the primer layer is 3 μm or more, good adhesion to the rubber layer can be easily obtained. Further, when the thickness of the primer layer is 7 μm or less, the coated metal plate can be easily thinned. From the above viewpoint, the thickness of the primer layer is more preferably 4 to 6 μm.

1-2. Rubber layer The rubber layer is joined to the primer layer of the painted metal plate. The rubber layer is composed of a crosslinked product of a coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based crosslinking agent. The coating composition for a rubber layer is a coating composition in which a fluorine-containing polymer and a polyol-based cross-linking agent are dispersed or dissolved in a solvent.

(Fluorine-containing polymer)
The fluorine-containing polymer is not particularly limited, and examples thereof include a copolymer of vinylidene fluoride and a fluorine-containing olefin other than vinylidene fluoride, and a copolymer of a fluorine-containing olefin and propylene. Examples of fluorine-containing olefins include vinylidene fluoride, hexafluoropropene, pentafluoropropene, tetrafluoroethylene, trifluorochloroethylene, vinyl fluoride, and perfluoro (methyl vinyl ether).

Examples of the fluorine-containing polymer include vinylidene fluoride copolymers such as vinylidene fluoride / hexafluoropropene binary copolymer and vinylidene fluoride / hexafluoropropene / tetrafluoroethylene ternary copolymer.

(Polyprethane cross-linking agent)
Examples of polyol-based cross-linking agents include polyhydroxyaromatic compounds such as 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) perfluoropropane, and hydroquinone.

The content of the polyol-based cross-linking agent is preferably 2.5 to 10% by mass with respect to the fluorine-containing polymer. When the content of the polyol-based cross-linking agent is 2.5% by mass or more, it is easy to sufficiently cross-link the fluorine-containing polymer and the cross-linking density can be appropriately increased, so that not only sufficient rubber elasticity can be easily obtained but also sufficient rubber elasticity can be easily obtained. Easy to reduce rubber flow. Further, since the reaction point with the epoxy resin contained in the primer layer also increases, the adhesiveness between the rubber layer and the primer layer is likely to be further enhanced. When the content of the polyol-based cross-linking agent is 10% by mass or less, the cross-linking density does not become too high, so that the rubber elasticity is not easily impaired. The content of the polyol-based cross-linking agent is more preferably 3 to 6% by mass with respect to the fluorine-containing polymer.

(PTFE particles)
The composition containing the fluorine-containing polymer and the polyol-based cross-linking agent preferably further contains PTFE particles from the viewpoint of adjusting the coating film cohesive force of the rubber layer.

The PTFE particles preferably have an average particle size of 3 to 6 μm and a content of 1 to 5% by mass with respect to the fluorine-containing polymer. When the average particle size of the PTFE particles is 3 μm or more and the content of the PTFE particles with respect to the fluorine-containing polymer is 1% by mass or more, the cohesive force of the coating film of the rubber layer can be appropriately reduced. When the average particle size of the PTFE particles is 6 μm or less and the content of the PTFE particles with respect to the fluorine-containing polymer is 5% by mass or less, the coating film cohesive force of the rubber layer is unlikely to be excessively reduced. From the same viewpoint, it is more preferable that the PTFE particles have an average particle size of 4 μm and a content of 1.5 to 2.5% by mass with respect to the fluorine-containing polymer.

As described above, by setting the average particle size of the PTFE particles to 3 to 6 μm and the content with respect to the fluorine-containing polymer to 1 to 5% by mass, the coating film cohesive force of the rubber layer is appropriately lowered within a predetermined range. Can be made to. As a result, even when immersed in an antifreeze solution, good adhesiveness between the primer layer and the rubber layer can be further maintained.

(solvent)
The solvent may be any one that dissolves the fluorine-containing polymer, and examples thereof include isophorone and cyclohexanone.

(Other ingredients)
The coating composition for a rubber layer may further contain components other than the fluorine-containing polymer, if necessary. Examples of other components include reinforcing materials such as carbon black and silica, acid acceptors such as magnesium oxide, zinc oxide and hydrotalcite, lubricants such as stearic acid, tetramethyltyuralam disulfide and N-cyclohexyl-2-. Includes cross-linking accelerators such as benzothiazyl sulfenamide. Above all, from the viewpoint of increasing the interfacial strength with the primer layer and making it easier to further enhance the high temperature sliding resistance, the rubber layer preferably further contains a reinforcing material.

The content of the reinforcing material is preferably, for example, 50% by mass or less, and more preferably 5 to 20% by mass, based on the fluorine-containing polymer. The total content of the other components is preferably 15% by mass or less with respect to the crosslinked product of the coating composition for the rubber layer.

The thickness of the rubber layer is preferably, for example, 5 to 40 μm from the viewpoint of satisfying the performance required for the gasket for the engine cylinder head. When the thickness of the rubber layer is 5 μm or more, sufficient sealing property is likely to be exhibited, and when it is 40 μm or less, the gasket does not become too thick. From the above viewpoint, the thickness of the rubber layer is more preferably 12 to 30 μm.

1-3. Layer structure The composite of the present invention may further have other layers, if necessary.

FIG. 1A is a schematic cross-sectional view showing an example of the composite of the present invention, and FIG. 1B is a partially enlarged schematic cross-sectional view of FIG. 1A.

As shown in FIGS. 1A and 1B, the composite 100 has a coated metal plate 110 and a rubber layer 120. The coated metal plate 110 has a metal plate 111, a chemical conversion treatment film 112, and a primer layer 113. The primer layer 113 has a swelling portion 113A on the surface layer portion on the side where the rubber layer 120 is laminated (see FIG. 1B).

As described above, the primer layer 113 maintains the coating film cohesive force by containing silica particles having an average particle size of micron order while having a swelling portion 113A on the surface layer portion on the side where the rubber layer 120 is laminated. can do. As a result, good adhesion to the rubber layer 120 can be maintained even when vibration is applied at a high temperature.

2. Method for Producing Composite The method for producing a composite of the present invention is as follows: (1) a step of preparing a coated metal plate, and (2) applying a coating composition for a rubber layer on a primer layer of the coated metal plate and then cross-linking. It has a step of forming a rubber layer.

About the step (1) First, a chemical conversion treatment liquid is applied to the surface of a metal plate to form a chemical conversion treatment film.

As the metal plate, the above-mentioned one can be used. If necessary, the metal plate may be subjected to known pre-painting treatment such as degreasing and pickling.

The chemical conversion treatment liquid may be an aqueous solution containing the above-mentioned silane coupling agent and an organic resin. If necessary, the chemical conversion treatment liquid may further contain a small amount of alcohol, a ketone, a cellosolve-based water-soluble organic solvent, or the like, in addition to water.

The chemical conversion treatment liquid may further contain a curing agent for curing the organic resin, if necessary. Examples of the curing agent include isocyanate compounds such as diisocyanate compounds having an aromatic ring and aliphatic diisocyanate compounds, and polycarbodiimide compounds.

The solid content concentration of the chemical conversion treatment liquid is preferably 0.1 to 40% by mass. When the solid content concentration is 0.1% by mass or more, a chemical conversion-treated film having a sufficient thickness can be easily obtained. On the other hand, when the solid content concentration is 40% by mass or less, the storage stability of the chemical conversion treatment liquid is not easily impaired. The pH of the chemical conversion treatment liquid is preferably adjusted in the range of 3 to 12.

Then, the chemical conversion treatment liquid is applied to the surface of a metal plate that has been subjected to alkaline degreasing by a roll coating method, a spray method, a curtain flow method, a spin coating method, a dip coating method, etc., and dried at room temperature without washing with water. .. Although it is possible to form a chemical conversion treatment film by drying at room temperature, it is preferable to shorten the drying time at a temperature of 50 ° C. or higher in consideration of continuous operation. However, from the viewpoint of surely suppressing the thermal decomposition of the organic component contained in the chemical conversion treatment film, the drying temperature is preferably 200 ° C. or lower.

Next, an epoxy resin composition (resin composition for a primer layer) containing the above-mentioned epoxy resin, a curing agent, and silica particles is applied onto the chemical conversion-treated film of the obtained steel sheet, and baked to form a primer layer. Form.

When the curing agent is an isocyanate compound, the isocyanate compound in the resin composition for the primer layer is blocked with alcohol or the like from the viewpoint of enhancing the storage stability (from the viewpoint of enhancing the pot life of the composition for the primer layer). Is preferable.

The resin composition for the primer layer may further contain a solvent, if necessary, from the viewpoint of improving coating workability. The solvent is not particularly limited, but examples thereof include alcohol solvents such as methanol, ethanol, isopropanol and 1-butanol, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, and benzene solvents such as xylene. Is included. These solvents may be one kind or a combination of two or more kinds.

The method for applying the resin composition for the primer layer is not particularly limited, and a known method may be appropriately selected.

The baking method of the resin composition for the primer layer is not particularly limited, and the solvent may be volatilized. The baking temperature may be a temperature at which the solvent can be volatilized within a range in which the curable resin in the coating film is not completely cured, and is not particularly limited. For example, the ultimate plate temperature at the time of baking is 180 to 210 ° C. Is preferable.

The coating composition for a rubber layer containing the above-mentioned fluorine-containing polymer, polyol-based cross-linking agent, and solvent is applied onto the primer layer of the obtained coated metal plate in the step (2).

The method for applying the coating composition for the rubber layer is not particularly limited, and may be, for example, a screen printing method, a roll coating method, a curtain flow method, a dip coating method, or the like.

Next, the coating composition for a rubber layer applied on the primer layer of the coated metal plate is dried and crosslinked to form a rubber layer.

The coating composition for a rubber layer is preferably dried and crosslinked by heating. The heating method is not particularly limited, but may be, for example, heating with hot air.

Further, the coating composition for the rubber layer may be dried and crosslinked at the same time or sequentially. From the viewpoint of joining the rubber layer and the primer layer with sufficient adhesiveness, for example, it is preferable to dry the coating composition for the rubber layer (drying step) and then crosslink the rubber layer (crosslinking step).

The drying temperature may be a temperature such that the solvent of the coating composition for the rubber layer volatilizes, and may be, for example, 150 to 200 ° C. The drying time can be, for example, about 5 to 30 minutes.

The cross-linking temperature may be any temperature as long as the fluorine-containing polymer of the rubber layer coating composition is cross-linked, and may be, for example, 200 to 260 ° C., depending on the composition of the rubber layer coating composition. The cross-linking time can be, for example, about 5 to 60 minutes.

3. 3. Applications of the composite The composite of the present invention can be used in various applications where heat resistance and sealing properties are required. Above all, the composite of the present invention has good heat resistance and sealing property, and therefore can be preferably used as a gasket for an engine cylinder head.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to these Examples.

1. 1. Material preparation (1) Metal plate <Metal plate M1>
SUS301-CSP-H (Austenitic stainless steel plate, thickness 0.2 mm)

<Metal plate M2>
NSS431-DP2 manufactured by Nisshin Steel Co., Ltd. (ferritic stainless steel, thickness 0.2 mm)

<Metal plate M3>
Hot-dip galvanized steel sheet in which both sides of a steel sheet with a thickness of 0.5 mm are hot-dip galvanized (plating single-sided adhesion amount 90 g / m ² )

<Metal plate M4>
Hot-dip plated steel sheet with both sides of a 0.8 mm thick steel sheet plated with hot-dip aluminum (plating single-sided adhesion amount 40 g / m ² )

(2) Chemical conversion treatment liquid <Preparation of chemical conversion treatment liquid C1>
A chemical conversion treatment solution having a solid content concentration of 5% by mass by adding a mixture of N- (2-aminoethyl) aminopropyltriethoxysilane and a urethane resin (mass ratio 6: 4) to water containing 10% by mass of ethanol. Obtained C1.

<Preparation of chemical conversion treatment liquid C2>
A chromate-free chemical conversion treatment liquid was obtained by adding 20 g / L of Ti compound and 40 g / L of phenol resin to pure water (solvent).

<Preparation of chemical conversion treatment liquid C3>
A coating type chromate treatment agent (Surfcoat NRC300, manufactured by Nippon Paint Co., Ltd.) was used.

(3) Resin composition for primer layer (epoxy resin composition)
<Preparation of resin composition PC1 for primer layer>
20% by mass of curing agent (methylenediphenyldiisocyanate) and 10% by mass of inorganic aggregate (average particle size 5 μm) with respect to epoxy resin (modified bisphenol A type epoxy resin modified with a compound having a hydroxyl group and an amino group). Was dissolved in a mixed solvent of xylene, cyclohexanone and 1-butanol) to obtain a primer resin composition PC1.

<Preparation of resin composition PC2-12 for primer layer>
Primer layer resin compositions PC2-12 were obtained in the same manner as the primer layer resin composition PC1 except that the number average molecular weight of the epoxy resin and / or the type of curing agent was changed as shown in Table 1.

<Preparation of resin compositions PC13 to 47 for primer layer>
Primer layer resin compositions PC13-47 were obtained in the same manner as the primer layer composition PC3, except that the average particle size and / or content of the silica particles was changed as shown in Table 2 or 3.

<Preparation of resin composition PC48 for primer layer>
A primer layer resin composition PC48 was obtained in the same manner as the primer layer resin composition PC1 except that the type of resin was changed as shown in Table 3.

The compositions of the obtained primer layer resin compositions PC1 to 12 are shown in Table 1, the compositions of PC13 to 33 are shown in Table 2, and the compositions of PC34 to 48 are shown in Table 3.

The abbreviations in the table are as follows.
MDI: Methylene diphenyl diisocyanate (aromatic)
TDI: Tolylene diisocyanate (aromatic)
XDI: Xylylene diisocyanate (aromatic)
HDI: Hexamethylene diisocyanate (aliphatic)
IPDI: Isophorone diisocyanate (alicyclic)
2E4MZ: 2-Ethyl-4-methylimidazole polyester resin: Hydroxy group-containing polyester resin

The number average molecular weight of the epoxy resin and the average particle size of the silica particles contained in the resin composition for the primer layer were measured by the following methods.

(Number average molecular weight)
The number average molecular weight of the epoxy resin was measured by the gel permeation chromatography method. Specifically, the measurement was performed under the following measurement conditions.
A GPC apparatus HLC-8010 manufactured by Tosoh Corporation was used as the GPC apparatus, two columns K-800D and K805L manufactured by Shodex Co., Ltd. were used as columns, and chloroform was used as the eluent. The values of weight average molecular weight (Mw) and number average molecular weight (Mn) were converted from standard polystyrene.

(Average particle size)
The average particle size of the silica particles in the resin composition was measured by a laser particle size distribution meter (SALD7100, manufactured by Shimadzu Corporation).

(4) Paint composition for rubber layer <Preparation of paint composition R1 for rubber layer>
5% by mass polyol cross-linking agent, 15% by mass carbon black and 10% by mass PTFE particles (PTFE micropowder, molecular weight 100,000, average particle diameter 4 μm) are dispersed in isophorone with respect to a ternary fluororubber polymer. Then, a coating composition R1 for a rubber layer was obtained.

<Preparation of paint composition R2 for rubber layer>
A rubber layer coating composition R2 was obtained in the same manner as the rubber layer coating composition R1 except that PTFE particles were not added.

2. Preparation and evaluation of complex <Preparation of complex 1>
(1) Preparation of Painted Metal Plate PCM1 First, the surface of SUS301-CSP-H (metal plate M1) having a thickness of 0.2 mm was alkaline degreased. The chemical conversion treatment liquid C1 prepared above was applied onto the alkali degreased surface of the steel sheet by a bar coating method and then dried to form a chemical conversion treatment film having ^{a film adhesion amount of 100 mg / m 2.} Next, the resin composition PC1 for a primer layer is applied onto the chemical conversion-treated film by a bar coating method, and then baked at a plate reaching temperature of 200 ° C. to form a primer layer having a thickness of 5 μm and a surface roughness of Ra 0.8 μm, which is then coated. A metal plate PCM1 was obtained.

The surface roughness Ra of the primer layer of the coated metal plate PCM1 was measured by the following method.

(Surface roughness Ra)
The surface roughness Ra (arithmetic mean roughness) of the primer layer of the coated metal plate PCM1 was measured using SURFCOM 130A manufactured by Tokyo Seimitsu Co., Ltd. in accordance with JIS B0601-2001.

(2) Preparation of Composite 1 Next, the prepared coating composition R1 for a rubber layer was screen-printed on the obtained coated metal plate PCM1 and temporarily dried at a temperature of 170 ° C. for 20 minutes (drying step). Then, the rubber layer was further dried (crosslinked step) at 250 ° C. for 30 minutes to laminate a rubber layer having a thickness of 20 μm. As a result, a composite 1 of a coated metal plate PCM1 and a rubber layer was obtained.

In the obtained composite 1, a swelling portion formed by permeation of the solvent component of the rubber layer coating composition R1 is formed on the surface layer portion of the primer layer on the rubber layer side. It was confirmed by low vacuum SEM observation of the cross section.

<Preparation of complexes 2-55>
Composites 2 to 55 were obtained in the same manner as in Complex 1 except that the types of the coated metal plates were changed as shown in Tables 4 to 6.

<Preparation of complexes 56 and 59>
Composites 56 and 59 were obtained in the same manner as in composites 3 and 34, respectively, except that the types of the coating composition for the rubber layer were changed as shown in Table 7.

<Preparation of complexes 57 and 58>
Composites 57 and 58 were obtained in the same manner as in Complex 3 except that the thickness of the rubber layer was changed as shown in Table 7.

The antifreeze resistance and high temperature sliding resistance of the obtained composites 1 to 59 were evaluated by the following methods.

(Antifreeze resistance)
The obtained composite was half-immersed in a 50% by volume aqueous diluted solution of antifreeze (long life coolant manufactured by Toyota) and kept at 150 ° C. for 24 hours in a pressure vessel. After that, a spiral with a radius of 4.5 mm was drawn 25 times on the surface of the composite pulled up from the antifreeze according to the drawing test specified in JIS K6894, and the boundary between the unimmersed part (gas phase) and the immersed part (liquid phase) was drawn. The peeled state of the rubber layer (gas-liquid interface) was evaluated according to the following criteria.
◯: The thickness of the drawing line is less than 300 μm and the rubber layer is not peeled off. Δ: The thickness of the drawing line is 300 μm or more and the rubber layer is not peeled off. Peeling occurred at one or more places (site). If it was Δ or more, it was judged to be good.

(High temperature sliding resistance)
The high temperature sliding resistance of the obtained composite was performed by a rubbing tester (manufactured by Ohira Rika Kogyo). Specifically, the composite is fixed on a stage heated to 150 ° C., and a SUS304 steel ball having a diameter of about 5 mm is used as a friction partner, and the stage is rubbed under the conditions of a stage moving width of 50 mm, a frequency of 50 Hz, and a load of 400 g. A dynamic test (friction wear test) was performed.
Then, the evaluation of the high temperature slidability was performed by the number of reciprocations until the primer layer became visible due to wear or peeling of the rubber layer in 80% of the portions where the steel balls came into contact. Specifically, the evaluation was made according to the following criteria.
◯: The number of round trips is 20 times or more Δ: The number of round trips is 10 times or more and less than 20 times ×: The number of round trips is less than 10 times Δ or more is judged to be good.

The evaluation results of complexes 1 to 12 are shown in Table 4, the evaluation results of complexes 13 to 38 are shown in Table 5, the evaluation results of complexes 39 to 55 are shown in Table 6, and the evaluation results of complexes 56 to 59 are shown. Each is shown in 7.

As shown in Tables 4 and 5, it has a chemical conversion coating and a primer layer, the primer layer contains silica particles having an average particle diameter of 2 to 10 μm, and the surface roughness Ra is 0.1 to 1. It can be seen that the composites 1 to 38 having a thickness of 10 μm have good antifreeze resistance and high temperature sliding resistance.

In particular, it can be seen that when the curing agent is a curing agent containing an aromatic ring, the high temperature sliding resistance is further enhanced (compared with composites 3, 4, 10 and 11). It is considered that this is because the heat resistance of the primer layer is increased and the adhesiveness between the primer layer and the rubber layer can be maintained.

Further, it can be seen that when the number average molecular weight of the epoxy resin is 2000 or more, the antifreeze resistance is enhanced, and when it is 8000 or less, the high temperature sliding resistance is enhanced (comparison of composites 1 to 5, 8 and 9). ..

Further, as shown in Table 7, it can be seen that the antifreeze resistance of the complex is improved by containing the PTFE particles in the rubber layer (comparison between the complexes 56 and 3 and a comparison between the complexes 59 and 34). ). It is considered that this is because the addition of the PTFE particles weakened the cohesive force of the crosslinked product (fluorine rubber) of the fluorine-containing polymer, and the cohesive force of the primer layer and the cohesive force of the rubber layer were balanced.

On the other hand, as shown in Table 6, the composites 39, 41, 45, 49, 51 and 54 having an average particle size of silica particles contained in the primer layer of less than 1 μm have a surface roughness Ra of 0. It was as small as less than 1 μm. Therefore, it can be seen that the high temperature sliding resistance is low. Further, it can be seen that the composites 40, 42, 46, 50 and 52 having an average particle size of the silica particles contained in the primer layer exceeding 10 μm have low antifreeze resistance and high temperature sliding resistance. Further, it can be seen that the composite 53 having no chemical conversion treatment film has low antifreeze resistance and high temperature sliding resistance. Further, in the composite 54 having both the thickness of the primer layer and the average particle diameter of the silica particles of 1 μm, the surface roughness Ra of the primer layer is as small as less than 0.1 μm, and both antifreeze resistance and high temperature sliding resistance are low. Recognize.

According to the present invention, it is possible to provide a composite, a gasket, and a method for producing a composite, which can be obtained by a simple method and has good antifreeze resistance and high temperature sliding resistance.

100 Composite 110 Painted metal plate 120 Rubber layer 111 Metal plate 112 Chemical conversion coating 113 Primer layer 113A Swelling part

Claims (15)

A composite having a coated metal plate having a metal plate, a chemical conversion coating film, and a primer layer in this order, and a rubber layer bonded to the primer layer of the coated metal plate.
The rubber layer is composed of a crosslinked product of a coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based crosslinking agent.
The primer layer comprises a cured product of an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm.
The primer layer has a bulging portion on the surface layer portion on the rubber layer side, and the surface roughness Ra on the rubber layer side of the primer layer is 0.1 to 10 μm.
Complex. The thickness of the primer layer is 3 to 7 μm.
The complex according to claim 1. The content of the silica particles is 1 to 20% by mass with respect to the epoxy resin.
The complex according to claim 1 or 2. The number average molecular weight of the epoxy resin is 2000 to 8000.
The complex according to any one of claims 1 to 3. The curing agent is an isocyanate compound and
The epoxy resin is a modified epoxy resin having a functional group that reacts with an isocyanate group.
The complex according to any one of claims 1 to 4. The curing agent is an aromatic isocyanate compound.
The complex according to claim 5. The coating composition for a rubber layer further contains PTFE particles.
The complex according to any one of claims 1 to 6. The chemical conversion coating is a chromate-free coating containing an amino group-containing silane coupling agent and an organic resin.
The complex according to any one of claims 1 to 7. Consists of the complex according to any one of claims 1 to 8.
gasket. It has a metal plate, a chemical conversion coating, and a primer layer in this order.
The primer layer is a cured product of an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm, and the surface roughness Ra of the primer layer is 0.1 to 10 μm. The process of preparing the board and
A coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based cross-linking agent is applied onto the primer layer of the coated metal plate and then cross-linked to form a rubber layer bonded to the primer layer. Process and
Have,
Method of manufacturing the complex. A coated metal plate for joining with a rubber layer composed of a crosslinked product of a coating composition for a rubber layer containing a fluorine-containing polymer and a polyol-based cross-linking agent.
It has a metal plate, a chemical conversion coating, and a primer layer in this order.
The primer layer is arranged on the outermost surface layer of the coated metal plate, and is composed of a cured product of an epoxy resin composition containing an epoxy resin, a curing agent, and silica particles having an average particle diameter of 2 to 10 μm.
The surface roughness Ra of the primer layer is 0.1 to 10 μm.
Painted metal plate. The thickness of the primer layer is 3 to 7 μm.
The coated metal plate according to claim 11. The curing agent is an isocyanate compound and
The epoxy resin is a modified epoxy resin having a functional group that reacts with an isocyanate group.
The coated metal plate according to claim 11 or 12. The curing agent is an aromatic isocyanate compound.
The coated metal plate according to claim 13. The chemical conversion coating is a chromate-free coating containing an amino group-containing silane coupling agent and an organic resin.
The coated metal plate according to any one of claims 11 to 14.

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