CN113930096A

CN113930096A - Composite material, method for the production thereof and use thereof

Info

Publication number: CN113930096A
Application number: CN202010608119.2A
Authority: CN
Inventors: 齐藤俊
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2020-06-29
Filing date: 2020-06-29
Publication date: 2022-01-14

Abstract

The invention discloses a composite material, a manufacturing method and application thereof. The composite material comprises in sequence: a metal substrate; a zinc coating layer on the metal substrate; a zinc phosphate layer on the zinc coating, wherein the zinc content of the zinc phosphate layer is 0.001-1.0 g/m²(ii) a And a fluorine-containing coating film on the zinc phosphate layer, the fluorine-containing coating film containing less than 70 fluorine atomsAmount% of fluororesin.

Description

Composite material, method for the production thereof and use thereof

Technical Field

The present invention relates to a composite material having improved corrosion resistance and long-term weathering life. The invention also relates to a manufacturing method of the composite material and application of the composite material, such as railways, bridges, transmission towers, communication towers and the like made of the composite material.

Background

At present, with the advance of a new infrastructure construction policy, construction projects such as intercity railways, bridges, transmission towers, communication towers and the like are laid in various places and are actively developed. These infrastructure facilities use a large number of metal structures such as steel structures, and the steel structures are generally made of galvanized steel.

The protective effect of the zinc coating on the steel structure is dual, firstly, the zinc coating with good anti-permeability performance completely isolates the protected metal from the corrosive environment, thereby completely eliminating the electrolyte which is a main condition for the corrosion of the metal; secondly, the chemical activity of zinc is higher than that of iron, so that the zinc is easier to be corroded and dissolved (sacrificed), once a zinc coating is locally damaged and steel is exposed, the zinc becomes an anode and corrodes before the iron, and the purpose of protecting the steel is achieved.

In summer, Xin ' coating for hot-dip galvanized steel ' (see the known net) ' in order to save steel, reduce maintenance and further prolong the service life, the galvanized steel is required to be protected, namely the coating is coated on the surface of the galvanized steel to form a double-layer anti-corrosion system in a matching way ', ' the problem of poor adhesion of a coating film on the hot-dip galvanized steel exists at home and abroad ', and the pretreatment of the surface of the galvanized layer ' comprises ' wind erosion, oil removal, phosphorization and chromate treatment '.

Phosphorization is a common pretreatment technology, belongs to chemical conversion film treatment in principle, and is mainly applied to the phosphorization of steel surfaces, and nonferrous metal (such as aluminum and zinc) parts can also be applied to phosphorization. Phosphating is a process in which chemical and electrochemical reactions form a phosphate chemical conversion coating, which is referred to as a phosphating coating. The purpose of the phosphorization is mainly as follows: the base metal is protected, and the metal is prevented from being corroded to a certain extent; the primer is used for priming before painting, and the adhesive force and the corrosion resistance of a paint film layer are improved.

Shenzhou in "galvanized steel coating" ("Shanghai paint" volume 44, 8 th 2006, 8 th month) "mentions that" although the galvanized layer has good corrosion resistance and protective properties, "in some cases, it is necessary to apply a liquid paint or a powder paint on the surface of the galvanized layer," and "the steel structure has a longer service life due to the double protection of an organic coating layer and a galvanized layer in a severe corrosion environment," coating systems for galvanized steel exemplified by "epoxy primer", "acrylic primer and topcoat", "alkyd paint", and the like. It also mentions: "As with all steel structure painting operations, the key to the painting of galvanized steel structures is the surface pretreatment prior to painting. However, the surface conditions of the galvanized steel structure are different from those of the common steel structure, and the surface pretreatment of the galvanized steel structure before painting cannot be completely applied to the treatment method of the common steel structure.

Polyurethane resin, chlorinated rubber, alkyd resin, and the like are known as organic coatings applied to the surface of galvanized steel, but these coatings have insufficient effects of prolonging the service life of steel, may rust and corrode after five years in coastal environments, and have basically no finish function after twenty years. In addition, the liquid coating is inconvenient to operate when coating galvanized steel, and particularly has large engineering quantity when coating large-scale facilities such as a power transmission iron tower, is easy to cast all around, has wide influence range and is unfavorable for the environment.

In recent years, fluororesin coatings, particularly fluorine-containing powder coatings, have been developed for coating the surface of galvanized steel. The fluorine-containing powder coating has the corrosion resistance effect on the aspects of reagent resistance and insolation resistance which is obviously better than that of coatings such as polyurethane resin, chlorinated rubber, alkyd resin and the like, has super weather resistance and high corrosion resistance, can protect steel products for a long time, reduces the recoating times and greatly prolongs the service life of the steel products. Furthermore, the fluororesin coating can be cured under a wide range of temperature conditions from normal temperature to high temperature, and can be coated either in a factory or on site. For example, in the construction of a power transmission tower, steel materials of each part are coated with a fluororesin coating material to perform an anticorrosive treatment, and then assembled at a construction site.

Korea-Yan et al, "research progress of anticorrosive coating of polytetrafluoroethylene" ("plastics", volume 36, No. 2, 2007) points out: the organic fluorine polymer has excellent chemical resistance, heat resistance, weather resistance, non-stick performance, lubricating performance and the like, is more and more emphasized by people, and is widely used for heavy corrosion protection. High-grade decoration. Anti-sticking and lubricating treatment. Of all organofluoropolymers, Polytetrafluoroethylene (PTFE) has the best corrosion resistance and is most widely used.

To further improve the corrosion resistance of galvanized structures, attempts have been made to apply a PTFE coating to the galvanized structure by phosphating the galvanized surface with zinc phosphate prior to application to improve the adhesion (or adhesion) of the galvanized surface to the galvanized structure.

Pipes were mentioned from "organofluoropolymer coatings and their use in corrosion protection" by westerner et al (corrosion science and protection technology, vol. 12, vol. 3, month 5, 2000): numerous studies have demonstrated that the reasons for coating failure are: (1) poor surface treatment (40%), poor coating selection (20%), non-uniform coating thickness (20%), and (4) inadequate coating preparation (coating, etc.) (20%).

It is clear that the choice of the surface treatment method and the coating compatible therewith has a critical effect on the corrosion resistance of the final coated product.

Accordingly, there remains a need to provide a composite material having improved corrosion protection and long-term weathering life, and methods of making and using the same.

Disclosure of Invention

It is an object of the present invention to provide a composite material having improved corrosion protection and long-term weathering life.

It is another object of the present invention to provide a method for manufacturing the composite material.

It is also an object of the present invention to provide uses of the composite material.

Accordingly, one aspect of the present invention relates to a composite material comprising, in order: a metal substrate; a zinc coating layer on the metal substrate; a zinc phosphate layer on the zinc coating, wherein the zinc content of the zinc phosphate layer is 0.001-1.0 g/m²(ii) a And a fluorine-containing coating film on the zinc phosphate layer, the fluorine-containing coating film containing a fluorine resin having a fluorine atom content of less than 70 mass%.

Another aspect of the invention relates to a method of making the composite material, comprising: forming a zinc coating layer on a metal substrate; phosphating the metal base material with zinc phosphate to form zinc content of 0.001-1.0 g/m²A zinc phosphate layer of (a); and coating a fluorine-containing powder coating on the surface of the zinc phosphate to form a fluorine-containing coating film, wherein the fluorine-containing powder coating contains a fluorine resin having a fluorine atom content of less than 70 mass%.

A further aspect of the invention relates to the use of the composite material according to the invention for construction.

Detailed Description

The inventionThe composite material comprises the following components in sequence: a metal substrate; a zinc coating layer on the metal substrate; a zinc phosphate layer on the zinc coating, wherein the zinc content of the zinc phosphate layer is 0.001-1.0 g/m²(ii) a And a fluorine-containing coating film on the zinc phosphate layer, the fluorine-containing coating film containing a fluorine resin having a fluorine atom content of less than 70 mass%.

[ Metal base Material ]

The metal substrate in the composite material of the present invention is not particularly limited and may be a conventional metal material known in the art. In one example of the invention, the metallic material comprises a ferrous alloy, steel, or a steel clad non-metallic material. In one embodiment of the present invention, the metal substrate is a metal material, preferably a steel material, which is commonly used in construction projects such as railways, bridges, power transmission towers, and communication towers.

[ Zinc plating layer ]

The zinc coating in the composite material of the present invention serves primarily to prevent corrosion of the metal substrate in contact with, for example, air and water. The zinc coating layer suitable for the composite material of the present invention is not particularly limited and may be a conventional zinc coating layer known in the art.

In an embodiment of the present invention, the thickness of the galvanized layer is 30 to 500 μm, preferably 40 to 200 μm, more preferably 50 to 100 μm, and even more preferably 60 to 80 μm. When the thickness of the galvanized layer is within the above range, the corrosion resistance and the acid resistance are excellent, and cracks do not occur in the water resistance test.

In one embodiment of the present invention, the zinc-coated layer has a zinc adhesion amount of 200 to 1000g/m²Preferably 300 to 900g/m²More preferably 400 to 800g/m²Most preferably 500 to 700g/m². When the zinc adhesion amount of the zinc plating layer is within the above range, the corrosion resistance and the acid resistance are excellent, and cracks do not occur in the water resistance test.

The method for forming the zinc plating layer in the composite material of the present invention is not particularly limited, and may be a conventional method known in the art. In one example of the present invention, the zinc coating layer may be formed by immersing the metal substrate in a zinc melt at 400 to 1000 ℃.

[ Zinc phosphate layer ]

The inventor of the invention researches and discovers that the combination of a specific zinc phosphate layer and a special fluorine resin layer can favorably improve the interlayer adhesiveness and the corrosion resistance of the composite material and further prolong the weather-proof life of the composite material. The present invention has been completed based on this finding.

Thus, the composite material of the present invention includes a specific zinc phosphate layer on the zinc coating layer. The zinc content of the zinc phosphate layer is 0.001-1.0 g/m²Preferably 0.001 to 0.6g/m²More preferably 0.001 to 0.3g/m²Further, it is preferably 0.001 to 0.2g/m²Or preferably 0.001 to 0.1g/m². The zinc content of the zinc phosphate layer is within a specified range, so that the corrosion resistance and the adhesion with the upper fluorine-containing coating can be effectively obtained at the same time, and the long-term weather aging resistance is achieved.

In one embodiment of the present invention, the ratio of zinc in the zinc phosphate layer to zinc in the zinc plating layer (zinc in the zinc phosphate layer/zinc in the zinc plating layer) is in the range of 0.0005 to 0.005, more preferably in the range of 0.0005 to 0.002, and further preferably in the range of 0.0005 to 0.001. In the case where seawater is splashed in large quantities in coastal areas, zinc is easily converted into water-soluble substances such as zinc chloride, and the long-term corrosion resistance cannot be maintained if the zinc is quickly dissolved out. If the ratio of zinc in the zinc phosphate layer to zinc in the zinc-plated layer is within the above-mentioned predetermined range, the zinc is less likely to be changed to zinc chloride or the like, so that the zinc phosphate layer can always be kept in close contact with the fluorine-containing coating film while covering the entire surface of the zinc-plated layer.

The zinc phosphate layer in the composite material of the present invention can be obtained by subjecting the metal base material on which the zinc plating layer has been formed to phosphating with zinc phosphate. The specific phosphating treatment method is not particularly limited, and may be a zinc phosphating treatment method known in the art. For example, a zinc phosphate layer can be formed on a galvanized layer by a T Wash method (T Wash is a treatment agent which stabilizes an oxide on the surface of a galvanized metal structure and is a modified aqueous zinc phosphate solution containing a small amount of copper salt), or by treating the surface of a galvanized layer with a phosphating primer, or the like.

[ fluorine-containing coating film ]

The composite material of the present invention includes a fluorine-containing coating film on a zinc phosphate layer, the fluorine-containing coating film containing a fluorine resin having a fluorine atom content of less than 70 mass%. In one example of the present invention, the fluorine-containing coating film contains a fluorine resin having a fluorine atom content of less than 50 mass%. In one embodiment of the present invention, the fluorine-containing coating film is a crosslinked film. In one embodiment of the present invention, the fluorine-containing coating film is a crosslinked film containing a crosslinked product of a fluororesin having a crosslinkable group. In one embodiment of the present invention, the fluorine-containing coating film is formed by coating a fluorine-containing powder coating material containing a fluorine resin.

In one embodiment of the present invention, the fluorine-containing coating film has a film thickness of 30 to 200 μm, preferably 50 to 150 μm, more preferably 80 to 120 μm, and still more preferably 90 to 110 μm.

In one embodiment of the present invention, the fluorine-containing coating film has an elongation of 30 to 200%, preferably 50 to 150%, more preferably 60 to 120%, and still more preferably 70 to 110%.

In one embodiment of the present invention, the fluorine-containing coating film has a breaking strength of 5 to 100MPa, preferably 10 to 80MPa, more preferably 10 to 50MPa, and still more preferably 10 to 40 MPa.

In one embodiment of the present invention, the fluorine-containing coating film is a crosslinked film having a crosslinking density of 0.5X 10^－4～10×10^－4(mol/cm)³) Preferably 1X 10^－4～9×10^－4(mol/cm)³) More preferably 3X 10^－4～8×10^－4(mol/cm)³) More preferably 7X 10^－4～8×10^－4(mol/cm)³)。

In one embodiment of the present invention, the fluorine-containing coating film is preferably a crosslinked film containing a crosslinked product of a fluororesin having a crosslinkable group. The crosslinkable group may, for example, be a hydroxyl group, a carboxyl group, an amino group, an alkoxysilyl group or an epoxy group, and preferably a hydroxyl group or a carboxyl group from the viewpoint of water resistance, chemical resistance, impact resistance and the like of the fluorine-containing coating film.

In one embodiment of the present invention, the powder coating material can be prepared by feeding the fluororesin and optionally other components such as the non-fluororesin, the curing agent and the pigment into a kneading extruder to perform melt-kneading, cooling and pulverizing.

In one example of the present invention, a powder coating material can be produced by melt-kneading a fluororesin and optionally a non-fluororesin, cooling and pulverizing, followed by mixing it with a curing agent and other ingredients.

< fluororesin >

The fluororesin used as a raw material contains a fluoropolymer containing a fluoroolefin-based unit. The fluoroolefin is an olefin in which 1 or more hydrogen atoms are replaced by fluorine atoms. The number of fluorine atoms in the fluoroolefin is preferably 2 or more, more preferably 3 to 4. In the fluoroolefin, 1 or more of hydrogen atoms not substituted by fluorine atoms may be substituted by chlorine atoms.

As a specific example of the fluoroolefin, CF is exemplified₂＝CFCl、CF₂＝CHF、CH₂＝CF₂、CF₂＝CFCF₃、CF₂＝CHCF₃、CF₃CH＝CHF、CF₃CF＝CH₂From the viewpoint of polymerizability, CF is preferred₂＝CFCl、CF₃CHF or CF₃CF＝CH₂. The fluoroolefin may be used in combination of 2 or more.

The fluorine-containing polymer may contain only the fluoroolefin-based unit, may contain a unit based on a fluorine-containing monomer other than the fluoroolefin, and may contain a unit based on a non-fluorine-containing monomer.

The fluoropolymer containing only a fluoroolefin-based unit may, for example, be a homopolymer of a fluoroolefin or a copolymer of two or more fluoroolefins, and specifically may, for example, be polychlorotrifluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, or polyvinylidene fluoride.

As the fluorine-containing polymer containing a unit based on a fluorine-containing monomer other than the fluoroolefin, a fluoroolefin-perfluoro (alkyl vinyl ether) copolymer may be mentioned, and a fluoroolefin-perfluoro (C) is preferred_1-10Alkyl vinyl ether) copolymer, more preferably fluoroolefin-perfluoro (C)_1-6Alkyl vinyl ether) copolymer, specifically, tetrafluoroethylene-holo-copolymerFluoro (alkyl vinyl ether) copolymers, preferably tetrafluoroethylene-perfluoro (C)_1-10Alkyl vinyl ether) copolymer, more preferably tetrafluoroethylene-perfluoro (C)_1-6Alkyl vinyl ether) copolymer.

The content of the fluoroolefin-based unit in the entire units contained in the fluoropolymer is preferably 5 to 100 mol%, more preferably 20 to 70 mol%, and particularly preferably 40 to 60 mol%.

When the fluoropolymer contains a unit based on a non-fluorine monomer, the unit preferably contains a unit based on a monomer having a crosslinkable group. In this case, if a curing agent is contained as a raw material, the crosslinkable group serves as a crosslinking point, and the crosslinking reaction of the fluoropolymer bond proceeds through the curing agent, thereby improving the physical properties of the cured film. The crosslinkable group may, for example, be a hydroxyl group, a carboxyl group, an amino group, an alkoxysilyl group or an epoxy group, and from the viewpoint of water resistance, chemical resistance, impact resistance and the like of the cured film, a hydroxyl group or a carboxyl group is preferred, and a hydroxyl group is more preferred.

Examples of the monomer having a crosslinkable group include carboxylic acids polymerizable with vinyl alcohol or fluoroolefin, and vinyl ethers, vinyl esters, allyl ethers, allyl esters, acrylic esters, and methacrylic esters having a crosslinkable group, and specifically, may include CH₂＝CHCOOH、CH(CH₃)＝CHCOOH、CH₂＝C(CH₃) COOH, formula CH₂＝CH(CH₂)_n2A compound represented by COOH (wherein n2 represents an integer of 1 to 10), and CH₂＝CHO-CH₂-Ring C₆H₁₀-CH₂OH、CH₂＝CHCH₂O-CH₂-Ring C₆H₁₀-CH₂OH、CH₂＝CHOCH₂CH₂OH、CH₂＝CHCH₂OCH₂CH₂OH、CH₂＝CHOCH₂CH₂CH₂CH₂OH、CH₂＝CHCH₂OCH₂CH₂CH₂CH₂OH、CH₂＝CHCOOCH₂CH₂OH、CH₂＝C(CH₃)COOCH₂CH₂And (5) OH. In addition, "-Ring C₆H₁₀- "denotes cyclohexylidene," -ring C₆H₁₀The bonding site of the- "is usually 1, 4-.

The monomer having a crosslinkable group may be used in combination of 2 or more.

The content of the unit based on the monomer having a crosslinkable group in all the units contained in the fluoropolymer is preferably 0.5 to 35 mol%, more preferably 3 to 30 mol%, particularly preferably 5 to 25 mol%, most preferably 5 to 20 mol%, from the viewpoint of excellent physical properties of the cured film.

The fluoropolymer may also contain units based on monomers that do not contain fluorine atoms and do not have crosslinkable groups. The above-mentioned unit may, for example, be an olefin, a vinyl ether, a vinyl ester, an allyl ether, an allyl ester, an acrylic ester, a methacrylic ester or the like, and specific examples thereof may, for example, be ethylene, propylene, ethyl vinyl ether, 2-ethylhexyl vinyl ether, vinyl acetate, vinyl benzoate, methyl acrylate, methyl methacrylate, butyl acrylate or butyl methacrylate.

Among them, the fluoropolymer preferably contains units based on a monomer having an alkyl group having a tertiary carbon atom having 3 to 9 carbon atoms or a cycloalkyl group having 4 to 10 carbon atoms in a side chain, from the viewpoint of Tg of the fluoropolymer. However, this unit does not contain a fluorine atom and a crosslinkable group.

Examples of the alkyl group having a tertiary carbon atom and having 3 to 9 carbon atoms or the cycloalkyl group having 4 to 10 carbon atoms include a tert-butyl group, a neononyl group, a cyclohexyl group, a cyclohexylmethyl group, a 4-cyclohexylcyclohexyl group, and a 1-decahydronaphthyl group.

Specific examples of the above units include cyclohexyl vinyl ether, t-butyl vinyl ether, vinyl pivalate, vinyl t-butyl benzoate and vinyl neononanoate. The above units may be used in combination of 2 or more.

The content of the unit based on the monomer having no fluorine atom and no crosslinkable group in all the units contained in the fluoropolymer is preferably 5 to 60 mol%, more preferably 10 to 50 mol%, from the viewpoint of Tg of the fluoropolymer and flexibility of the cured film.

The content of the fluoroolefin-based unit, the crosslinkable group-containing monomer-based unit, and the fluorine atom-free crosslinkable group-free monomer-based unit in the fluoropolymer are preferably 20 to 70 mol%, 0.5 to 35 mol%, and 5 to 60 mol% in this order based on all units of the fluoropolymer.

The Mn of the fluoropolymer is preferably 3000 to 50000, more preferably 5000 to 30000, from the viewpoint of water resistance and smoothness of the cured film.

When the fluororesin contains a fluoropolymer having hydroxyl groups, the hydroxyl value is preferably 5 to 200mg KOH/g, more preferably 10 to 150mg KOH/g, from the viewpoint of adhesion.

When the fluororesin contains a fluorine-containing polymer having a carboxyl group, the acid value is preferably 1 to 150mg KOH/g, more preferably 3 to 100mg KOH/g, and particularly preferably 5 to 50mg KOH/g, from the viewpoint of adhesion.

The fluoropolymer may have only either one of the acid value and the hydroxyl value, or both of them. When the fluoropolymer has both an acid value and a hydroxyl value, the total of the acid value and the hydroxyl value is preferably 1 to 80mg KOH/g. When the total of the acid value and the hydroxyl value is within the above range, the Tg of the fluoropolymer can be appropriately adjusted, and the cured film has excellent physical properties.

The melting point of the fluororesin is preferably 300 ℃ or lower, more preferably 200 ℃ or lower, and particularly preferably 180 ℃ or lower. The fluororesin preferably has a Tg of 30 to 150 ℃, more preferably 40 to 120 ℃, and still more preferably 50 to 100 ℃ from the viewpoint of blocking resistance of the powder coating and smoothness of the cured film.

The fluorine atom content of the fluororesin is a ratio (% by mass) of a mass of a fluorine atom to a total mass of the fluororesin. In the present invention, the fluorine atom content of the fluororesin is less than 70% by mass, more preferably less than 50% by mass. In one embodiment of the present invention, the fluorine atom content of the fluororesin is 10 to 70% by mass, preferably 15 to 50% by mass, and more preferably 20 to 30% by mass. When the fluorine atom content of the fluororesin is within the above range, the adhesion between the fluorine-containing coating film and the lower layer is more excellent, and the effects of corrosion resistance, water resistance and acid resistance are more excellent, thereby achieving long-term weather resistance.

In one embodiment of the present invention, the method for producing a fluororesin includes introducing an organic solvent, a fluoroolefin monomer, an optional non-fluorine monomer, and a polymerization initiator into an autoclave, and heating the autoclave to perform a polymerization reaction to obtain a powdery fluororesin.

< non-fluororesin >

The raw material for the fluorine-containing powder coating material may optionally contain a non-fluororesin in addition to the fluororesin. The non-fluororesin is preferably a resin having low compatibility with the fluororesin. For example, the difference between the SP value of the fluororesin and the SP value of the non-fluororesin is preferably 0.6 to 0.9. Examples of the non-fluororesin include polyester resins, acrylic resins, epoxy resins, polyethylene resins, and urethane resins. Among them, from the viewpoint of the balance between weather resistance and cost, polyester resins or acrylic resins are preferable, and polyester resins are more preferable. These resins may be used in combination of 2 or more.

When the polyester resin is contained as a non-fluororesin, the polyester resin has a structure in which a unit based on a polycarboxylic acid compound and a unit based on a polyol compound are bonded to each other via an ester bond. The polyester resin may also contain a hydroxycarboxylic acid-based unit or the like as a unit other than the carboxylic acid unit and the alcohol unit.

The polyester resin can be, for example, a polymer having a unit derived from an aromatic polycarboxylic acid compound having 8 to 15 carbon atoms and a unit derived from a polyhydric alcohol compound having 2 to 10 carbon atoms.

The hydroxyl value of the polyester resin is preferably 20 to 100mg KOH/g, more preferably 30 to 80mg KOH/g. The acid value of the polyester resin is preferably 1 to 80mg KOH/g, more preferably 3 to 50mg KOH/g.

In view of the melt viscosity of the powder coating material, the polyester resin preferably has Mn of 5000 or less and Mw of 6000 to 20000, and more preferably has Mn of 5000 or less and Mw of 6000 to 10000.

Specific examples of the polyester polymer include "CryLCOAT (registered trademark) 4642-3", "CryLCOAT (registered trademark) 4890-0", manufactured by Nippon Cyanite industries, Ltd. "GV-250", "GV-740" and "GV-175", manufactured by Nippon Youbijia Ltd.

The acrylic resin preferably contains a unit based on one or more selected from acrylic acid and methacrylic acid, and a unit based on one or more selected from acrylic acid esters and methacrylic acid esters.

Specific examples of the acrylic resin include "ファインディック (registered trademark) A-249", "ファインディック (registered trademark) A-251", "ファインディック (registered trademark) A-266", available from DIC corporation, "アルマテックス (registered trademark) PD 6200", "アルマテックス (registered trademark) PD 7310", available from Sanyo chemical corporation, "サンペックス PA-55", available from Sanyo chemical corporation.

The epoxy resin is a compound having 2 or more epoxy groups in a molecule. As the curable epoxy resin, aromatic compounds having a glycidyloxy group such as bisphenol a-diglycidyl ether are preferable.

Specific examples of the epoxy resin include "エピコート (registered trademark) 1001", "エピコート (registered trademark) 1002", "エピコート (registered trademark) 4004P" manufactured by mitsubishi chemical corporation, "エピクロン (registered trademark) 1050", "エピクロン (registered trademark) 3050" manufactured by DIC corporation, "エポトート (registered trademark) YD-012", "エポトート (registered trademark) YD-014" manufactured by seikagaku chemical co., ltd, "デナコール (registered trademark) EX-711" manufactured by changi chemical technology corporation, and "EHPE 3150" manufactured by cellosolve corporation.

The urethane resin is a mixture of a polyol (acrylic polyol, polyester polyol, polyether polyol, propylene glycol, etc.) and an isocyanate compound, or a resin obtained by reacting the mixture, and is preferably a mixture of a powdery polyol (acrylic polyol, polyester polyol, polyether polyol) and a powdery isocyanate.

The non-fluororesin is preferably a solid non-fluororesin having a softening point of 100 to 150 ℃ at room temperature, a glass transition temperature Tg of 30 to 60 ℃ and a melting point of 200 ℃ or less.

In one embodiment of the present invention, the content of the fluororesin in the raw material of the fluorine-containing powder coating material is 5 to 95% by mass, preferably 8 to 80% by mass, more preferably 10 to 70% by mass, and most preferably 20 to 50% by mass, based on the total amount of the raw material.

In one embodiment of the present invention, the mass ratio of the fluororesin to the non-fluororesin (mass of fluororesin/mass of non-fluororesin) contained in the raw material for the fluorine-containing powder coating material is 70/30 to 10/90, preferably 50/50 to 30/70.

In one embodiment of the present invention, the total mass of the fluororesin and the non-fluororesin may be 30 to 100% by mass, 40 to 90% by mass, or 50 to 80% by mass based on the total mass of the raw material or the fluorine-containing powder coating material.

< curing agent >

In one embodiment of the present invention, it is preferable that the raw material of the fluorine-containing powder coating material may contain a curing agent in addition to the fluororesin and the non-fluororesin. However, the curing agent may be added after the fluororesin and the non-fluororesin are kneaded and pulverized, without adding the curing agent at the stage of the raw material. In addition, the fluororesin and the non-fluororesin may not be added with the curing agent if they can be cured by other methods without the curing agent.

As the curing agent, a known compound can be used, and examples thereof include blocked isocyanate-based curing agents, amine-based curing agents such as melamine resins, guanamine resins, sulfonamide resins, urea resins and aniline resins, β -hydroxyalkylamide-based curing agents and triglycidyl isocyanurate-based curing agents. The curing agent may be used in combination of 2 or more.

The softening temperature of the curing agent is preferably 10-120 ℃, and more preferably 40-100 ℃. When the softening temperature is 10 ℃ or higher, the powder coating material can be prevented from being cured at room temperature and forming granular lumps. When the temperature is 120 ℃ or lower, the curing agent can be homogeneously dispersed in the raw material in the kneading step, and the smoothness of the obtained cured film, the strength of the cured film, and the like can be improved.

The content of the curing agent is preferably 1 to 50% by mass, and more preferably 3 to 30% by mass, based on 100% by mass of the raw material of the powder coating material.

< other ingredients >

The raw material of the fluorine-containing powder coating material may optionally contain other components in addition to the fluororesin, the non-fluororesin and the curing agent. Examples of the other components include pigments, curing catalysts, degassing agents, surface conditioning agents, ultraviolet absorbers, matting agents such as ultrafine synthetic silica, nonionic, cationic or anionic surfactants, leveling agents, fillers, heat stabilizers, tackifiers, dispersants, antistatic agents, rust inhibitors, silane coupling agents, antifouling agents, and low-fouling treatment agents.

By including the pigment in the fluororesin coating powder, the ultraviolet rays can be blocked and the UV deterioration of the zinc phosphate layer can be prevented.

As the pigment, at least 1 selected from the group consisting of a bright pigment, an anticorrosive pigment, a coloring pigment and a filling pigment is preferable. Examples of the bright pigment include aluminum powder, nickel powder, stainless steel powder, copper powder, bronze powder, gold powder, silver powder, mica powder, graphite powder, glass flake, and scale-like iron oxide powder. As the rust preventive pigment, preferred are lead-free rust preventive pigments which are small in load on the environment, and examples thereof include zinc cyanamide, zinc oxide, zinc phosphate, calcium magnesium phosphate, zinc molybdate, barium borate, calcium cyanamide zinc, and the like. The coloring pigment is a pigment for coloring the cured film. Examples of the coloring pigment include titanium oxide, carbon black, iron oxide, phthalocyanine blue, phthalocyanine green, quinacridone, isoindolinone, benzimidazolone, and dioxazine. Examples of the filler pigment include talc, barium sulfate, mica, and calcium carbonate.

The content of the pigment in the fluororesin coating powder coating material is preferably 20 to 200% by mass, more preferably 50 to 150% by mass, based on 100% by mass of the fluororesin in the fluororesin coating powder coating material.

The curing catalyst may be, for example, a tin catalyst such as tin octylate, tributyltin dilaurate or dibutyltin dilaurate. The curing catalyst may be used in combination of 2 or more. The content of the curing catalyst is preferably 0.0001 to 10.0 parts by mass based on 100 parts by mass of the total solid content other than the pigment.

< method for coating fluorine-containing powder coating >

The above components are mixed, the obtained mixture is melt-kneaded as a raw material, the obtained kneaded product is cooled at 0 to 40 ℃, and the obtained kneaded product is pulverized by a pulverizer such as a rolling mill or a mill to obtain a powder composition, and the powder composition is classified to obtain a powder coating material. The cooling may be rapid cooling or slow cooling. In the powder coating material obtained by pulverization, the average particle diameter of the powder particles may be 120 μm or less, preferably 90 μm or less, from the viewpoint of surface smoothness of the cured film.

The method of coating the fluorine-containing powder coating material of the present embodiment may, for example, be an electrostatic coating method, an electrostatic spraying method, an electrostatic dipping method, a spraying method, a fluidized dipping method, a spraying method, a thermal spraying method, a plasma spraying method, or the like. Among them, the flow impregnation method is preferable. The metal base material on which the zinc plating layer and the zinc phosphate layer have been formed is immersed in a fluidized tank in which a fluorine-containing powder coating material is fluidized, and cured to form a fluorine-containing coating film.

In one embodiment of the present invention, the curing temperature is 150 to 250 ℃, preferably 180 to 230 ℃, and more preferably 190 to 210 ℃.

The fluorine-containing coating film formed by the method of the present invention has good followability to an underlayer and a substrate, has improved adhesion to a zinc phosphate layer, has an increased elongation, is less likely to peel off even if it expands and contracts by heat, and is less likely to cause problems such as coating film curling and warping by relaxing stress concentration at the coating film interface even if a crack is formed in the coating film.

The thickness of the fluorine-containing coating film formed from the fluorine-containing powder coating material may be 30 to 200. mu.m, preferably 50 to 150. mu.m, more preferably 80 to 120. mu.m, and still more preferably 90 to 110. mu.m. The fluorine-containing coating film having a thickness within the above range can prevent UV deterioration of the zinc phosphate layer by making it difficult for ultraviolet rays to pass therethrough, and is excellent in mechanical strength and visual properties.

[ method for producing composite Material ]

The method for manufacturing the composite material of the present invention comprises: forming a zinc coating layer on a metal substrate; phosphating the metal base material with zinc phosphate to form zinc content of 0.001-1.0 g/m²A zinc phosphate layer of (a); and coating a fluorine-containing powder coating on the surface of the zinc phosphate to form a fluorine-containing coating film, wherein the fluorine-containing powder coating contains a fluorine resin having a fluorine atom content of less than 70 mass%.

Thus, a composite material is produced by the manufacturing method of the present invention, which comprises, in order: a metal substrate; a zinc coating layer on the metal substrate; a zinc phosphate layer on the zinc coating, wherein the zinc content of the zinc phosphate layer is 0.001-1.0 g/m²(ii) a And a fluorine-containing coating film on the zinc phosphate layer, the fluorine-containing coating film containing a fluorine resin having a fluorine atom content of less than 70 mass%.

The composite material has improved anti-corrosion performance and long-term weather aging resistance life, can highly prevent corrosion even in a severe environment, has an ultra-long service life, and can be widely applied to construction projects such as intercity railways, bridges, transmission towers, communication towers and the like.

Examples

The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples.

Production example

[ production of fluororesin F1 ]

Xylene (503g), ethanol (142g), CTFE (387g), CHVE (326g), HBVE (84.9g), potassium carbonate (12.3g) and a xylene solution (20mL) containing 50 mass% t-butylperoxypivalate were introduced into the autoclave, and polymerization was carried out at 65 ℃ for 11 hours. Then, the autoclave solution was filtered to obtain a solution containing a fluorine resin F1 composed of a fluorine-containing polymer. The solvent in the resulting solution was removed by vacuum drying at 65 ℃ for 24 hours, and further vacuum dried at 130 ℃ for 20 minutes. The obtained block-shaped fluororesin F1 was pulverized to obtain a powdery fluororesin F1.

The fluororesin F1 thus obtained was a polymer containing, in the stated order, 50 mol% of units based on CTFE, 39 mol% of units based on CHVE, and 11 mol% of units based on HBVE (hydroxyl value: 50mg KOH/g, glass transition temperature Tg: 52 ℃, number average molecular weight Mn: 10000, fluorine atom content: 24 mass%) relative to the total units contained in the fluororesin F1.

[ production of fluororesin F2 ]

Tert-butanol (422g), xylene (106g), CTFE (465g), PV (440g) and UDA (103g) were introduced into the autoclave, and the temperature was raised, and a xylene solution (47mL) containing 50 mass% of tert-butylperoxypivalate as a polymerization initiator was continuously added thereto to carry out polymerization. After 11 hours, the autoclave was cooled with water to stop the polymerization, and the solution in the autoclave was filtered to obtain a solution containing a fluorine resin F2 composed of a fluorine-containing polymer. The solvent in the resulting solution was removed by vacuum drying at 65 ℃ for 24 hours, and further vacuum dried at 130 ℃ for 20 minutes. The obtained block-shaped fluororesin F2 was pulverized to obtain a powdery fluororesin F2.

The fluororesin F2 thus obtained was a polymer containing 41 mol% of units based on CTFE, 50 mol% of units based on PV and 9 mol% of units based on UDA in that order relative to the total units contained in the fluororesin F2 (hydroxyl value: 33mg KOH/g, glass transition temperature Tg: 52 ℃, number average molecular weight Mn: 16000, fluorine atom content: 24 mass%).

[ abbreviation in production example ]

CTFE: chlorotrifluoroethylene

PV: vinyl pivalate

UDA: undecylenic acid

CHVE: cyclohexyl vinyl ether

HBVE: 4-hydroxybutyl vinyl ether

Examples 1 to 10

[ production of fluorine-containing powder coating ]

Each of the components of the fluorine-containing powder coating material shown in Table 1 below was mixed for 10 seconds by a high-speed mixer (manufactured by Lingyu Co., Ltd.) to obtain a powdery mixture. The obtained mixture was used as a raw material, and melt-kneaded using a 2-axis extruder (a 25 mm-diameter screw extruder, manufactured by the company of space) to obtain a kneaded product.

The resulting kneaded mixture was gradually cooled to 23 ℃ and pulverized at 23 ℃ using a pulverizer (product name: DJ-05, manufactured by Ringyu Co., Ltd.) to obtain a powder composition, which was classified by 200 mesh to obtain a powder coating material (average particle diameter: 70 μm).

The components (% by mass) of the fluorine-containing powder coating material used in each example are shown in table 1 below.

TABLE 1

	1	2	3	4	5	6	7	8	9	10
											F1	68.1	68.1	68.1	68.1	－	－	－	35.3	68.1	68.1
F2	－	－	－	－	83.4	－	－	－	－	－
											PVDF	－	－	－	－	－	59.5	－	－	－	－
PTFE	－	－	－	－	－	－	100	－	－	－
											Polyester resin	－	－	－	－	－	－	－	35.3	－	－
Acrylic resin	－	－	－	－	－	25.5	－	－	－	－
											PFC105	15.0	15.0	15.0	15.0	15.0	15.0	－	15.0	15.0	15.0
B1530	16.9	16.9	16.9	－	－	－	－	14.4	16.9	16.9
											BF1540	－	－	－	16.9	－	－	－	－	－	－
Primid XL-552	－	－	－	－	1.6	－	－	－	－	－
											Degassing agent	0.4	0.4	0.4	0.4	0.4	0.4	－	0.4	0.4	0.4
Surface conditioner	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1	0.1

[ detailed description of the respective ingredients in Table 1 ]

F1: fluororesin F1 produced in production example 1

F2: fluororesin F2 produced in production example 2

PTFE: polytetrafluoroethylene, trade name "Fluon PTFE AD 911E" manufactured by AGC Co., Ltd "

PVDF: polyvinylidene fluoride, trade name "DS 203" of Dongye corporation "

Polyester resin: trade name "CryLCOAT (registered trademark) 4890-0" manufactured by Zhanxin Co., Ltd, Mn: 2500

Acrylic resin: DIC Kabushiki Kaisha "ファインディック A-254"

B1530: blocked isocyanate curing agent (product name of Degussa "Vestagon B1530")

BF 1540: isocyanate curing agent without blocking agent (product name "Vestagon BF 1540" from Degussa)

Primid XL-552: n, N, N ', N' -tetrakis- (2-hydroxyethyl) -adipamide, a curing agent having 2 or more beta-hydroxyalkylamides in one molecule, under the trade name "Primid XL-552" from EMS "

The PFC 105: titanium oxide pigment (Stone Material industry Co., Ltd.)

Benzoin: degassing agent

[ preparation of test piece ]

The steel material is immersed in a zinc bath in which zinc is hot-melted to form a zinc coating layer on the steel material. Then, zinc phosphate-based chemical conversion treatment is performed on the zinc plating layer to form a zinc phosphate layer. Then, the coating layer was formed by immersing the coating layer in a fluidized tank in which the fluorine-containing powder coating material flowed, and the coating layer was cured by holding the coating layer in an atmosphere at 200 ℃ for 20 minutes to form a fluorine-containing coating film. Thus, a composite material having a zinc plating layer, a zinc phosphate layer, and a fluorine-containing coating film in this order from the substrate side was obtained, and the following evaluation was performed using the composite material as a test piece. The evaluation results are shown in Table 2 below.

[ measurement method ]

Hydroxyl value and acid value: JIS K0070-3 (1992)

Glass transition temperature Tg: mid-point glass transition temperature of polymers as determined by Differential Scanning Calorimetry (DSC)

Number average molecular weight Mn: value obtained by measuring polystyrene as a standard substance by gel permeation chromatography

A unit: the unit is a general term for a radical which is directly formed by polymerization of a monomer and is derived from 1 molecule of the monomer and a radical obtained by chemically converting a part of the radical. The polymer was analyzed by Nuclear Magnetic Resonance (NMR) method, and the content (mol%) of each unit with respect to the total units contained in the polymer was determined.

Fluorine atom content: the fluorine atom content is a ratio (% by mass) of a mass of a fluorine atom to a total mass of the fluororesin, and is measured by a Nuclear Magnetic Resonance (NMR) method.

Crosslinking density: a film containing only a fluorine-containing coating film was prepared, and measurement was performed in a tensile mode using a fixed viscoelasticity measuring apparatus to find the temperature dependence of the storage elastic modulus (E'). The crosslinking density was calculated from the value of the flat region of the storage elastic modulus obtained according to the following equation.

Formula for calculating crosslink density:

n＝E'/3RT

n: crosslink Density (mol/cc) 1cm³＝1cc

R: gas constant (8.31J/k · mol ═ N · m/k · mol ═ 10⁷Dyne cm/k mol)

T: absolute temperature (K) of flat zone storage modulus of elasticity

E': flat area storage modulus of elasticity (dyne/cm)²)

Elongation and breaking strength: a film containing only a fluorine-containing coating film was prepared, and a tensile test and a breaking strength test were performed under the conditions that the size of the fluorine-containing coating film was 10mm × 100mm, the chuck pitch was 50mm, the tensile speed was 50 mm/min, and the temperature of a tensile constant temperature bath was 23 ℃.

Zinc adhesion on the zinc plating layer: measured by the direct method according to JIS H0401 (2007). Weighing the test piece before galvanization, then weighing the test piece after galvanization, and calculating the attachment amount by increment; alternatively, the thickness of the plated film of the product is measured by a magnetic measuring device, and the amount of adhesion is determined by conversion from the thickness of the plated film.

The conversion of the amount of deposit was such that the density of the zinc-plated film was 7.2g/cm³The counting is carried out by the following steps of,

A＝7.2×t

a: zinc adhesion (g/m)²)

t: coating thickness (mum)

Zinc content of the zinc phosphate layer: measured with an energy dispersive fluorescent X-ray analyzer manufactured by Nippon electronic Co.

[ evaluation method ]

Corrosion resistance

According to the salt water spray test method (JIS K5600-7-1: 1999). The corrosion-resistant treated surface side of the test piece was subjected to salt water spraying after crosscut, and after 3000 hours, the state of corrosion generated in the crosscut portion was observed and evaluated according to the following criteria.

A: rust is less, and the crosscut part can be clearly identified.

B: rust and difficulty in identifying the transected part.

C: a large amount of rust was generated, and cross-sectional site swelling and peeling were also observed.

Water resistance

The test piece was subjected to the following steps 1 to 3 of 30 cycles, and the abnormality of the anticorrosive treated surface of the test piece was visually observed and evaluated according to the following criteria.

Step 1: soaking in water at 20 deg.C for 16 hr

And a step 2: standing at-20 deg.C for 4 hr

Step 3: standing at 50 deg.C under high humidity environment with humidity of 98% for 4 hr

A: no abnormal condition on the anti-corrosion treated surface

B: swelling of the fluorine-containing coating film on the anticorrosive treated surface was observed

C: peeling or cracking of the fluorine-containing coating film on the anticorrosive treated surface was observed

Acid resistance

After the test piece was immersed in an aqueous sulfuric acid solution for 10 days, the state of the anticorrosive-treated surface of the test piece was visually observed, and evaluated according to the following criteria.

A: no abnormal condition on the anti-corrosion treated surface

B: swelling or discoloration of the fluorine-containing coating film on the anticorrosive treated surface was observed

C: peeling of the fluorine-containing coating film on the anticorrosive treated surface was observed

As is clear from the results shown in table 2, examples 1 to 2, 4 to 6 and 8 all showed good effects in corrosion resistance, water resistance and acid resistance, and particularly examples 1 to 2, 5 and 8 showed excellent adhesion between the fluorine-containing coating film and the lower layer, no corrosion of the coating film and no swelling of the coating film edge portion, and were extremely excellent in corrosion resistance, water resistance and acid resistance. In example 3, the zinc phosphate layer had a high zinc content, and therefore, the adhesion to the fluorine-containing coating film was poor, and the corrosion resistance and the water resistance were poor. In example 7, the fluororesin was PTFE having a high fluorine atom content, and the fluorine-containing coating film had poor adhesion to the lower layer, and was not excellent in corrosion resistance, water resistance, and acid resistance. In example 9, the zinc phosphate layer was not phosphated, the fluorine-containing coating film was hard to adhere to the zinc plating layer, and the corrosion resistance and the water resistance were not good, though the coating film had acid resistance. In example 10, the zinc adhesion amount of the zinc plating layer and the zinc content of the zinc phosphate layer were both high, and the zinc content was too high, and although corrosion was not easy, adhesion between the layers was difficult, and the water resistance was not good, and cracks were generated in the zinc plating layer.

Possibility of industrial utilization

Claims

1. A composite material comprising, in order:

a metal substrate;

a zinc coating layer on the metal substrate;

a zinc phosphate layer on the zinc coating, wherein the zinc content of the zinc phosphate layer is 0.001-1.0 g/m²(ii) a And

a fluorine-containing coating film on the zinc phosphate layer, the fluorine-containing coating film containing a fluorine resin having a fluorine atom content of less than 70 mass%.

2. The composite material of claim 1, wherein the metal substrate comprises steel.

3. The composite material according to claim 1, wherein the galvanized layer has a thickness of 30 to 500 μm and a zinc adhesion amount of 200 to 1000g/m²。

4. The composite material of claim 1, wherein the zinc phosphate layer has a zinc content of 0.001 to 0.3g/m²。

5. The composite material of claim 1, wherein the ratio of zinc in the zinc phosphate layer to zinc in the zinc coating layer is in the range of 0.0005 to 0.005.

6. The composite material according to claim 1, wherein the fluorine-containing coating film has a film thickness of 30 to 200 μm, an elongation of 30 to 200%, and a breaking strength of 5 to 100 MPa.

7. The composite material according to claim 1, wherein the fluorine-containing coating film is a crosslinked film having a crosslink density of 0.5 x 10^－4～10×10^－4Mole/cm³。

8. The composite material according to claim 1, wherein the fluorine-containing coating film contains a fluorine resin having a fluorine atom content of less than 50 mass%.

9. The composite material according to any one of claims 1 to 8, wherein the fluorine-containing coating film is a crosslinked film comprising a crosslinked product of a fluororesin having a crosslinkable group.

10. The composite material of claim 9, wherein the crosslinkable group is a hydroxyl group or a carboxyl group.

11. The composite material according to any one of claims 1 to 8, wherein the fluororesin comprises a fluoroolefin-based unitA member of the group consisting of fluoropolymers, said fluoroolefin being selected from CF₂＝CFCl、CF₂＝CHF、CH₂＝CF₂、CF₂＝CFCF₃、CF₂＝CHCF₃、CF₃CH＝CHF、CF₃CF＝CH₂At least one of (1).

12. The composite material according to any one of claims 1 to 8, wherein the fluororesin comprises a fluoropolymer comprising units based on a fluoroolefin selected from CF and units based on a non-fluorine monomer₂＝CFCl、CF₂＝CHF、CH₂＝CF₂、CF₂＝CFCF₃、CF₂＝CHCF₃、CF₃CH＝CHF、CF₃CF＝CH₂At least one of (1).

13. The composite material according to claim 12, wherein the unit based on the non-fluorine monomer contained in the fluororesin contains a unit based on a monomer having a crosslinkable group selected from CH₂＝CHCOOH、CH(CH₃)＝CHCOOH、CH₂＝C(CH₃)COOH、CH₂＝CH(CH₂)_n2COOH、CH₂＝CHO-CH₂-Ring C₆H₁₀-CH₂OH、CH₂＝CHCH₂O-CH₂-Ring C₆H₁₀-CH₂OH、CH₂＝CHOCH₂CH₂OH、CH₂＝CHCH₂OCH₂CH₂OH、CH₂＝CHOCH₂CH₂CH₂CH₂OH、CH₂＝CHCH₂OCH₂CH₂CH₂CH₂OH、CH₂＝CHCOOCH₂CH₂OH、CH₂＝C(CH₃)COOCH₂CH₂At least one of OH, wherein n2 represents an integer of 1 to 10.

14. A method of making a composite material comprising:

forming a zinc coating layer on a metal substrate;

phosphating the metal base material with zinc phosphate to form zinc content of 0.001-1.0 g/m²A zinc phosphate layer of (a); and

and coating a fluorine-containing powder coating on the surface of the zinc phosphate layer to form a fluorine-containing coating film, wherein the fluorine-containing powder coating comprises a fluorine resin with a fluorine atom content of less than 70 mass%.

15. The method for producing a composite material according to claim 14, wherein a fluorine-containing powder coating is applied to the surface of the zinc phosphate layer by a flow dip method.

16. Use of a composite material according to any one of claims 1 to 13 in construction.

17. Use according to claim 16, for railways, bridges, pylons and pylons.