JP2014019037A - Pipe and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe capable of achieving an improvement in corrosion resistance or a reduction in cost, and a method of manufacturing the same.SOLUTION: A pipe 1 includes: a tube 2; a first coat layer 3 which is formed of a first coating composition containing water, an organic solvent, a granular metal, a silane coupling agent, and a wetting agent and is formed on an inner surface of the tube 2; and a second coat layer 4 which is formed of a second coating composition containing both an organic component containing either a monomer containing a specific urethane bond-containing diol (meth)acrylate compound or a polymer obtained by polymerizing the monomer and an inorganic component and is formed on a surface of the first coat layer 3.

Description

  The present invention relates to a pipe and a manufacturing method thereof, and more particularly, to a pipe used for an engine system of an automobile and a manufacturing method thereof.

  2. Description of the Related Art Conventionally, in an automobile engine system, various pipes such as an intake pipe for supplying air to the engine, an exhaust pipe for discharging exhaust gas from the engine, and a fuel for supplying fuel to the engine, for example. A supply pipe, a cooling water supply pipe for supplying engine cooling water, and the like are used.

  Such pipes, especially pipes with liquids such as fuel and water on the inside, are corroded with long-term use and may cause liquid leakage. Improvement is demanded.

  As such a method, it has been studied to form a coating layer having excellent corrosion resistance on the inner surface of the pipe. Specifically, for example, (A) water, (B) low-boiling organic liquid, (C) granular metal , (D) a coating composition comprising an organofunctional silane binder and (E) a wetting agent is coated on a support and thermally cured by heating at about 204-343 ° C. for about 5 minutes or more to form a coating layer Has been proposed (see, for example, Patent Document 1).

  Further, in some cases, further excellent corrosion resistance may be required. In such a case, it is possible to improve the corrosion resistance by forming a similar coating layer on the coating layer. Have been studied (2-coat 2-bake method).

JP 2002-121485 A

  However, depending on the use of the pipe, as described above, there may be a case where even better corrosion resistance is required than when two coating layers described in Patent Document 1 are formed.

  Moreover, when forming two coating layers, since it is necessary to heat the apply | coated coating composition to high temperature (about 204-343 degreeC) in each layer, there exists a malfunction that cost starts.

  An object of the present invention is to provide a pipe capable of improving the corrosion resistance or reducing the cost, and a method for manufacturing the pipe.

  In order to achieve the above object, the pipe of the present invention comprises a pipe, a first coat layer formed on the inner surface of the pipe, and a second coat layer formed on the surface of the first coat layer, The first coat layer is formed from a first coating composition containing water, an organic solvent, a particulate metal, a silane binder, and a wetting agent, and the second coat layer is represented by the following general formula (1). An organic component containing a monomer containing a urethane bond-containing diol (meth) acrylate compound or a polymer obtained by polymerizing the monomer, and a second coating composition containing an inorganic component It is a feature.

(Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkylene group having 1 to 4 carbon atoms.)
The pipe manufacturing method of the present invention includes a step of preparing a pipe, and a first coating composition containing water, an organic solvent, a particulate metal, a silane binder and a wetting agent is applied to the inner surface of the pipe. And a monomer containing a urethane bond-containing diol (meth) acrylate compound represented by the following general formula (1): a step of forming a first coat layer on the inner surface of the tube by heating to 300 to 500 ° C. Or the 2nd coating composition containing the organic component containing the polymer obtained by superposing | polymerizing the monomer and an inorganic component is applied to the surface of the said 1st coating layer, and it heats at 50-200 degreeC. And a step of forming a second coat layer on the surface of the first coat layer.

(Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkylene group having 1 to 4 carbon atoms.)

  In the pipe of the present invention and the manufacturing method thereof, the pipe is formed from the second coating composition by heating at a relatively low temperature on the first coating layer formed from the first coating composition by heating at a relatively high temperature. A second coat layer is laminated.

  As such a pipe, for example, when a plurality of first coat layers (two layers) are stacked and a pipe is manufactured without stacking the second coat layer, excellent corrosion resistance can be secured, while the first coat layer is secured. There is a problem that the cost is increased because high temperature heating is required a plurality of times (twice) in forming the film.

  On the other hand, in the pipe of the present invention and the manufacturing method thereof, if one first coat layer and one second coat layer are formed, the number of times of heating at the time of forming the first coat layer is reduced, and the cost is reduced. Can be reduced. In addition, two layers of the first coat layer can be stacked, and excellent corrosion resistance comparable to that of a pipe manufactured without stacking the second coat layer can be ensured.

  Furthermore, in the pipe of the present invention and the manufacturing method thereof, two first coat layers are laminated, and if the second coat layer is laminated, two first coat layers are laminated, and the second coat layer is laminated. It is possible to ensure even better corrosion resistance than pipes manufactured without any problems.

It is a schematic sectional drawing which shows one Embodiment of the pipe of this invention. It is process drawing which shows the manufacturing method of the pipe shown in FIG. 1, (a) The process of preparing a pipe | tube, (b) The process of forming a 1st coating layer, (c) is a 2nd coating layer. The process to form is shown. It is a schematic sectional drawing which shows other embodiment of the pipe of this invention.

  FIG. 1 is a schematic sectional view showing an embodiment of the pipe of the present invention.

  In FIG. 1, a pipe 1 includes a pipe 2, a first coat layer 3 formed on the inner surface of the pipe 2, and a second coat layer 4 formed on the surface of the first coat layer 3.

  The pipe 2 is, for example, an intake pipe for supplying air to the engine in an engine system, an exhaust pipe for discharging exhaust gas from the engine, a fuel supply pipe for supplying fuel to the engine, an engine cooling water, for example It is a tubular member used as a cooling water supply pipe for supplying water, and is formed from a known metal material.

  The wall thickness and inner diameter of such a tube 2 are not particularly limited, and are appropriately set according to the purpose and application.

  The first coat layer 3 is formed from a first coating composition containing water, an organic solvent, a particulate metal, a silane binder, and a wetting agent.

  In the first coating composition, the content ratio of water is, for example, 20 to 70 parts by mass, preferably 25 to 60 parts by mass, and more preferably 30 to 100 parts by mass with respect to the total amount of the first coating composition. 60 parts by mass.

  Examples of the organic solvent include a low boiling point organic solvent and a high boiling point organic solvent.

  The low-boiling organic solvent is an organic solvent having a boiling point of less than 100 ° C. at normal pressure. Specifically, for example, low molecular weight alcohols such as methanol, ethanol, n-propanol, and isopropanol, such as acetone and methyl ethyl ketone And low boiling point ketones.

  These low boiling point organic solvents can be used alone or in combination of two or more.

  In the first coating composition, the content ratio of the low-boiling organic solvent is, for example, 1 to 30 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the first coating composition.

  The high-boiling organic solvent is an organic solvent having a boiling point of 100 ° C. or higher at normal pressure. Specifically, for example, glycols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, and tripropylene glycol; For example, the above-mentioned glycols such as monomethyl ether, dimethyl ether, ethyl ether and the like, for example, low molecular weight liquid polypropylene glycols such as diacetone alcohol, 1-nitropropane and the like can be mentioned.

  These high boiling point organic solvents can be used alone or in combination of two or more.

  In the first coating composition, the content of the high-boiling organic solvent is, for example, 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of the first coating composition.

  As these organic solvents, a low-boiling organic solvent or a high-boiling organic solvent can be used alone, or they can be used in combination. Preferably, the low boiling point organic solvent is used alone, or the low boiling point organic solvent and the high boiling point organic solvent are used in combination.

  The granular metal is granular, specifically, spherical or flaky (leaf-like) metal such as aluminum, manganese, cadmium, nickel, stainless steel, tin, iron, magnesium, zinc, and alloys thereof. Can be mentioned.

  These granular metals can be used alone or in combination of two or more.

  As a granular metal, Preferably, aluminum and zinc are mentioned.

  As for the size of the granular metal, all particles pass through 100 mesh, and most of them pass through 325 mesh (note that the mesh is an American standard sieve series).

  In the first coating composition, the content ratio of the granular metal is, for example, 10 to 35 parts by mass with respect to 100 parts by mass of the total amount of the first coating composition.

  Examples of the silane binder include a silane compound that can be diluted in water without causing gelation, for example, a trialkoxysilane in which a hydrogen atom is substituted with a monovalent organic functional group (hereinafter referred to as an organic functional group-containing trioxide). Alkoxysilane).

  Examples of the organic functional group include a vinyl group, a methacryloxyalkyl group, an aminoalkyl group, and an epoxy group.

  These organic functional groups can be used alone or in combination of two or more.

  The organic functional group is preferably an epoxy group.

  Examples of trialkoxysilanes include trimethoxysilane, triethoxysilane, tri-n-propoxysilane, and the like.

  These trialkoxysilanes can be used alone or in combination of two or more.

  Specific examples of the organofunctional group-containing trialkoxysilane include, for example, vinyl-substituted trialkoxysilanes (eg, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane), such as methacryloxyalkyl-substituted trialkoxysilane. Alkoxysilanes (eg, methacryloxypropyl-trimethoxysilane, methacryloxypropyl-triethoxysilane, methacryloxypropyl-trimethoxysilane, etc.), for example, aminoalkyl-substituted trialkoxysilanes (eg, 3-amino-propyltrimethoxy) Silane, 3-amino-propyltriethoxysilane, 3-amino-propyltripropoxysilane, etc., for example, epoxy-substituted trialkoxysilane (for example, β- (3,4-epoxysilane) Hexyl) ethyltrimethoxysilane - silane, 4- (trimethoxysilyl) butane-1,2 epoxide, such as γ- glycidoxypropyltrimethoxysilane), and the like.

  These organofunctional group-containing trialkoxysilanes can be used alone or in combination of two or more.

  The organofunctional group-containing trialkoxysilane is preferably an epoxy-substituted trialkoxysilane.

  In the first coating composition, the content ratio of the silane binder is, for example, 3 to 20 parts by mass, preferably 5 to 12 parts by mass with respect to 100 parts by mass of the total amount of the first coating composition.

  The blending ratio of the silane binder is, for example, 4.5 moles as the number of moles of alkoxy groups (trialkoxysilane alkoxy groups) bound to silane atoms with respect to the number of moles of water molecules in the first coating composition. , Preferably more than 5, more preferably more than 6.

  The wetting agent is a particulate metal dispersant (surfactant), and examples thereof include a nonionic wetting agent and an anionic wetting agent.

  Examples of the nonionic wetting agent include nonionic alkylphenol polyethoxy adducts (for example, ethoxylated nonylphenol and the like).

  Examples of the anionic wetting agent include organophosphates and diester sulfosuccinates (for example, sodium bistridecyl sulfosuccinate).

  These wetting agents can be used alone or in combination of two or more.

  The humectant is preferably a nonionic humectant.

  In the first coating agent, the content ratio of the wetting agent is, for example, 0.01 to 3 parts by mass with respect to 100 parts by mass of the total amount of the first coating agent.

  The first coating composition may be, for example, a corrosion inhibitor (for example, inorganic salt, boric acid, etc.), a rust inhibitor, a pH adjuster (for example, an alkali metal oxide, hydroxide, etc.), if necessary. Additives such as thickeners (for example, celluloses) and pigments (for example, phosphoric acids) can be contained.

  These additives can be used alone or in combination of two or more.

  The content ratio of the additive is not particularly limited, and is appropriately set according to the purpose and application.

  The first coating agent preferably contains chromium ions that do not contain chromium, specifically, trivalent or hexavalent chromium ions, such as ionic chromium ions provided by chromic acid or dichromate. It does not contain.

  The method for obtaining the first coating composition is not particularly limited, and the above-described components may be mixed by a known method at the above-described blending ratio.

  Specific examples of such a first coating composition include a coating composition obtained by the formulation and method described in paragraphs [0016] to [0043] of JP-A No. 2002-121485.

  And although mentioned later in detail, the 1st coat layer 3 is formed from said 1st coating composition.

The adhesion amount of the 1st coat layer 3 is 1-5 g / m < ² >, for example, Preferably, it is 2-4 g / m < ² >.

  The second coat layer 4 includes an organic component containing a monomer containing a urethane bond-containing diol (meth) acrylate compound represented by the following general formula (1) or a polymer obtained by polymerizing the monomer, and , Formed from a second coating composition containing an inorganic component.

(Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkylene group having 1 to 4 carbon atoms.)
In said formula (1), as R1, a hydrogen atom and a methyl group are mentioned, Preferably a hydrogen atom is mentioned.

  In the above formula (1), R2 is a linear alkylene group having 1 to 4 carbon atoms, specifically, a methylene group, an ethylene group, a trimethylene group, or a tetramethylene group, preferably a methylene group, An ethylene group is mentioned.

  Specific examples of such urethane bond-containing diol (meth) acrylate compounds include glycerol-1-methacryloyloxyethyl urethane and glycerol-1-acryloyloxyethyl urethane.

  These urethane bond-containing diol (meth) acrylate compounds can be used alone or in combination of two or more.

  As the urethane bond-containing diol (meth) acrylate compound, glycerol-1-methacryloyloxyethyl urethane is preferably used from the viewpoint of ease of synthesis.

  The method for synthesizing the urethane bond-containing diol (meth) acrylate compound is not particularly limited. For example, the method described in International Publication Pamphlet WO 2007/062304 [0014] to [0025] can be employed.

  Specifically, for example, first, a cyclic ketal and (meth) acryloyloxyethyl isocyanate are urethanated.

  Examples of the cyclic ketal include (R, S) -1,2-isopropylideneglycerol, (R, S) -sec-butylideneglycerol, and the like.

  These cyclic ketals can be used alone or in combination of two or more.

  The cyclic ketal is preferably (R, S) -1,2-isopropylideneglycerol from the viewpoint of easy reaction.

  Examples of (meth) acryloyloxyethyl isocyanate include methacryloyloxyethyl isocyanate and acryloyloxyethyl isocyanate.

  These (meth) acryloyloxyethyl isocyanates can be used alone or in combination of two or more.

  The (meth) acryloyloxyethyl isocyanate is preferably methacryloyloxyethyl isocyanate from the viewpoint of availability.

  In the urethanization reaction between the cyclic ketal and (meth) acryloyloxyethyl isocyanate, the blending ratio thereof is, for example, 1.1 to 3 mol of cyclic ketal with respect to 1 mol of (meth) acryloyloxyethyl isocyanate. It is.

  In the urethanization reaction, if necessary, a urethanization catalyst can be blended in order to shorten the reaction time.

  Examples of the urethanization catalyst include N-methylmorpholine, N-ethylmorpholine, dimorpholinomethane, ethylmorpholinoacetic acid, N- (3-dimethylaminopropyl) morpholine, N-methylpiperidine, quinoline, and 1,2-dimethylimidazole. N-methyldicyclohexylamine, triethylamine, pyridine, 1,4-diazabicyclooctane, tetramethyl-1,3-butanediamine, tetramethyl-1,3-propanediamine, dimethyldiethyl-1,3-propanediamine, Pentamethyldiethylenediamine, tetraethylmethanediamine, bis (2-dimethylaminoethyl) adipate, bis (2-diethylaminoethyl) adipate, dimethylcyclohexylamine, diethylcyclohexylamine, methyloctylcy Tertiary amine compounds such as rohexylamine and methyldodecylcyclohexylamine, such as tin chloride, tetra-N-butyltin, tetraphenyltin, tri-n-butyltin acetate, dimethyldichlorotin, di-n-butyltin diacetate, di Examples thereof include tin compounds such as -n-butyldichlorotin, di-n-butyltin dilaurate, di-n-butyltin dilaurate mercaptide, bis (2-ethylhexyl) tin oxide, and di-n-butyltin sulfide.

  These urethanization catalysts can be used alone or in combination of two or more.

  The urethanization catalyst is preferably a tertiary amine compound from the viewpoint of safety when the urethanization catalyst remains in the reaction product.

  In the case where the urethanization catalyst is blended, the blending ratio is, for example, 0.001 to 50 parts by weight, preferably 0.01 to 30 parts by weight with respect to 100 parts by weight of (meth) acryloyloxyethyl isocyanate. More preferably, it is 0.1-10 mass parts.

  Moreover, a solvent can also be mix | blended in a urethanation reaction.

  The solvent is not particularly limited as long as it does not react with (meth) acryloyloxyethyl isocyanate, and examples thereof include acetone, methyl ethyl ketone, acetonitrile, chloroform, carbon tetrachloride, dichloromethane, benzene, toluene, hexane, pyridine and the like. It is done.

  These solvents can be used alone or in combination of two or more.

  As a solvent, Preferably, acetone is mentioned from a viewpoint of the ease of solvent removal after reaction.

  When the solvent is blended, the blending ratio is, for example, 0.1 to 1000 parts by mass with respect to 100 parts by mass of (meth) acryloyloxyethyl isocyanate.

  The reaction temperature of the urethanization reaction is, for example, 0 to 100 ° C., preferably 25 to 80 ° C., more preferably 40 to 60 ° C., and the reaction time varies depending on the reaction temperature and the type and amount of the catalyst. For example, 6 to 24 hours.

  Thereby, a urethanization reaction product can be obtained.

  Examples of the urethanization reaction product include (R, S) -1,2-isopropylideneglycerol-3-methacryloyloxyethylurethane, (R, S) -sec-butylideneglycerol-3-methacryloyloxyethylurethane, and the like. Preferably, (R, S) -1,2-isopropylideneglycerol-3-methacryloyloxyethyl urethane is used.

  Next, in this method, the urethanization reaction product (the product obtained by the urethanation reaction) is subjected to a ring-opening reaction in a water-containing solvent in the presence of a catalyst.

  Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, and phosphoric acid, and organic acids such as p-toluenesulfonic acid.

  These catalysts can be used alone or in combination of two or more.

  As a catalyst, Preferably, hydrochloric acid is mentioned from a viewpoint of the ease of catalyst removal after reaction.

  The blending ratio of the catalyst is, for example, 0.1 to 10.0% by mass with respect to the entire reaction system.

  Examples of the water-containing solvent include water and a mixed solvent of water and a water-soluble solvent, and preferably a mixed solvent of water and a water-soluble solvent.

  Examples of the water-soluble solvent include methanol, ethanol, isopropanol, tetrahydrofuran (THF), acetonitrile, acetone, methyl ethyl ketone, dimethylformamide, dimethyl sulfoxide, dimethylacetamide and the like.

  These water-soluble solvents can be used alone or in combination of two or more.

  The water-soluble solvent is preferably methanol from the viewpoint of easy removal after the reaction.

  In the mixed solvent, the mixing ratio of water and the water-soluble solvent is not particularly limited, and is appropriately set depending on the purpose and application.

  The reaction temperature of the hydrolytic ring-opening reaction is, for example, 0 to 50 ° C., and the reaction time is, for example, 1 to 6 hours, although it varies depending on the reaction temperature, the type and amount of the catalyst, and the like. In the hydrolytic ring-opening reaction, a carbonyl compound may be by-produced in the reaction system as the reaction proceeds. In order to shorten the reaction time, the by-product carbonyl compound is reacted by, for example, distillation under reduced pressure. It can be removed from the system.

  Thereby, the urethane bond containing diol (meth) acrylate compound shown by the said Formula (1) can be obtained.

  Moreover, the monomer should just contain the urethane bond containing diol (meth) acrylate compound as an essential component, and can contain another monomer as an arbitrary component.

  Examples of other monomers include (meth) acrylic acid ester monomers, vinyl monomers, vinyl ether monomers, epoxy group-containing monomers, polyfunctional monomers, and crosslinkable monomers.

  Examples of the (meth) acrylic acid ester monomer include methyl (meth) acrylate, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 3-methacryloyloxypropyltrimethoxylsilane, pentachlorophenyl (meth) acrylate, α-naphthyl (meth) acrylate, pentabromophenyl (meth) acrylate, 2-methyl-2-adamantyl (meth) acrylate, 2- (perfluorohexyl) ) Ethyl (meth) acrylate, 1H-1- (trifluoromethyl) trifluoroethyl acrylate, and the like.

  Examples of the vinyl monomer include styrene, 2-chlorostyrene, β-bromostyrene, vinyl carbazole, and perfluorohexylethylene.

  Examples of vinyl ether monomers include methyl vinyl ether.

  Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate and 3,4-epoxycyclohexylmethyl (meth) acrylate.

  Examples of the polyfunctional monomer include ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and bisphenolethanol full orange acrylate.

  Examples of the crosslinkable monomer include N-methylol acrylamide and 4-hydroxybutyl acrylate glycidyl ether.

  These other monomers can be used alone or in combination of two or more.

  When the other monomer is included as a monomer, the content (total amount) of other monomers other than the crosslinkable monomer is 100 parts by mass with respect to the total amount of the organic component and the inorganic component described later. For example, it is 10-60 mass parts, Preferably, it is 10-40 mass parts.

  Moreover, when a monomer contains a crosslinkable monomer, the content rate of a crosslinkable monomer is 5-20 mass parts with respect to 100 mass parts of total amounts of an organic component and the inorganic component mentioned later, Preferably it is 5 parts. -10 parts by mass.

  As the organic component, a polymer of the above monomer can be used.

  Examples of the method for obtaining the polymer include radical polymerization and photopolymerization.

  In radical polymerization, for example, the above-described monomer is polymerized in the presence of a radical polymerization initiator.

  Examples of the radical polymerization initiator include organic peroxides such as benzoyl peroxide and t-butylperoxyneodecanoate, such as 2,2′-azobisisobutyronitrile and 2,2′-azobisisobutyric acid. Examples include azo compounds such as dimethyl.

  These radical polymerization initiators can be used alone or in combination of two or more.

  The radical polymerization initiator is preferably dimethyl 2,2'-azobisisobutyrate from the viewpoint of workability.

  The usage-amount of a radical polymerization initiator is 0.1-5.0 mass parts with respect to 100 mass parts of monomers, for example.

  The polymerization temperature and polymerization time vary depending on the type of radical polymerization initiator, the presence or absence of the other monomer, and the type thereof. For example, the above formula (1) is used without using the other monomer. In the case where only the urethane bond-containing diol (meth) acrylate compound represented by (2) is used and dimethyl 2,2′-azobisisobutyrate is used as the radical polymerization initiator, the polymerization temperature is, for example, 50 to 70 ° C. The polymerization time is, for example, 8 to 48 hours.

  In photopolymerization, polymerization is performed, for example, by irradiation with ultraviolet rays, visible light, electron beams, etc., utilizing the photopolymerizability of the urethane bond-containing diol (meth) acrylate compound represented by the above formula (1).

  Preferably, the photopolymerization is performed, for example, by irradiation with ultraviolet rays (UV) having a wavelength of 254 nm or electron beams (EB) with an acceleration voltage of 150 to 300 kV.

  Moreover, in photopolymerization, a photoinitiator can be used from a viewpoint of shortening reaction time as needed.

  Examples of the photopolymerization initiator include 2-hydroxy-2-methyl-1-phenyl-1-propanone and 1-hydroxy-cyclohexyl phenyl ketone.

  As the photopolymerization initiator, 2-hydroxy-2-methyl-1-phenyl-1-propanone is preferably used from the viewpoint of solubility in raw materials.

  The blending ratio of the photopolymerization initiator is, for example, 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the monomer.

  The polymerization temperature and polymerization time in photopolymerization vary depending on the type of photopolymerization initiator, the presence or absence of the above-mentioned other monomers, the type thereof, and the like, and are appropriately set according to the purpose and application.

  The polymer thus obtained is a structural unit derived from the urethane bond-containing diol (meth) acrylate compound represented by the above formula (1), specifically represented by the following general formula (2). It has a structural unit.

  The weight average molecular weight of a polymer is 5000-1 million, for example.

  In the second coating composition, the content ratio of the organic component is not particularly limited, but from the viewpoint of adhesion and coating workability, 1 to 80 parts by mass with respect to 100 parts by mass of the organic component and the inorganic component, Preferably, it is 10-80 mass parts.

  Examples of the inorganic component include an inorganic component that hybridizes with a urethane bond-containing diol (meth) acrylate compound (the above formula (1)) or a polymer thereof, for example, by a chemical bond such as a hydrogen bond, in an organic component. .

  The hydrogen bond is, for example, an oxygen atom present on the surface of the inorganic component, a functional group such as a hydroxyl group, an amino group, or a carboxyl group, and a urethane bond-containing diol (meth) acrylate compound (the above formula (1)) or It is formed between the hydroxyl group of the structural unit (formula (2)) in the polymer, the> N—H group, the> C═O group, etc. in the urethane bond portion. By such hydrogen bonding, a film having excellent durability can be obtained when the second coating composition is cured.

  Therefore, as an inorganic component, Preferably, the inorganic component which has functional groups, such as an oxygen atom, a hydroxyl group, an amino group, and a carboxyl group, on the surface is mentioned. In addition, these functional groups can also be obtained by surface-treating an inorganic component not having these functional groups by a known method.

  Specific examples of such inorganic components include metal alkoxides or hydrolysis condensates thereof.

  As a metal alkoxide, the compound represented by following General formula (3) is mentioned, for example.

M (OY) _m (X) _a-m (3)
(In the formula, M represents Si, Al, Ti, Zr, Ca, Fe, V, Sn, Li, Be, B, or P, and Y represents an alkyl group having 1 to 5 carbon atoms, or 2 carbon atoms. -4 represents an acyl group, and X is an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a functional group, and an aromatic group having 6 to 10 carbon atoms which may have a functional group. A hydrocarbon group or a halogen atom, a represents the same number as the valence of M, and m represents an integer from 1 to a.)
In the above formula (3), M is silicon (Si), aluminum (Al), titanium (Ti), zirconium (Zr), calcium (Ca), iron (Fe), vanadium (V), tin (Sn), It is selected from the group consisting of lithium (Li), beryllium (Be), boron (B) and phosphorus (P).

  M is preferably silicon (Si) from the viewpoints of easy availability and environmental load during use.

  In the above formula (3), Y represents an alkyl group having 1 to 5 carbon atoms or an acyl group having 2 to 4 carbon atoms.

  Examples of the alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, and isopentyl group. Etc.

  Examples of the acyl group having 2 to 4 carbon atoms include an acetyl group, a propionyl group, and a butyryl group.

  Y is preferably an alkyl group having 1 to 5 carbon atoms, more preferably a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and more preferably a methyl group from the viewpoint of volatility after hydrolysis. Group and ethyl group.

  In the above formula (3), X is an aliphatic hydrocarbon group having 1 to 10 carbon atoms which may have a functional group, or an aromatic hydrocarbon having 6 to 10 carbon atoms which may have a functional group. A group or a halogen atom;

  Examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n- Linear aliphatic alkyl groups such as pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group and n-decyl group, for example, alicyclic alkyl groups such as cyclohexyl group, etc. Preferably, a C2-C6 linear aliphatic alkyl group, More preferably, a methyl group and an ethyl group are mentioned.

  Examples of the aromatic hydrocarbon group having 6 to 10 carbon atoms include aryl groups such as a benzyl group and a phenyl group, and a phenyl group is preferable.

  Moreover, these C1-C10 aliphatic hydrocarbon groups and C6-C10 aromatic hydrocarbon groups may have a functional group, and as such a functional group, for example, a carboxyl group , A carbonyl group, an amino group, a vinyl group, an epoxy group, etc., preferably an epoxy group.

  As a halogen atom, a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom are mentioned, for example, Preferably, a chlorine atom is mentioned.

  As such a metal alkoxide, preferably, as described above, a metal alkoxide in which M is silicon (Si) can be mentioned. Specifically, for example, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane , Methyltriisopropoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, i-propyltrimethoxysilane, i-propyltriethoxysilane, butyltrimethoxysilane, Alkyl group-containing organoalkoxysilanes such as pentyltriethoxysilane, octyltriethoxysilane, decyltriethoxysilane, 2-norbornenetriethoxysilane, such as phenyltrimethoxysilane, phenyltrieth Phenyl group-containing alkoxysilanes such as silane, phenyltripropoxysilane, phenyltributoxysilane, phenyltriacetoxysilane, and benzyltriethoxysilane, and the phenyl of these phenyl group-containing alkoxysilanes are methyl, ethyl, and n-propyl. An organoalkoxysilane substituted with a group, isopropyl group, t-butyl group or halogen, and further, for example, tetramethoxysilane, tetraethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ- Methacryloxypropyltrimethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, -Chlorophenyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, 3- Phenylaminopropyltrimethoxysilane, 3-cyclohexylaminopropyltrimethoxysilane, 3- (2-aminoethylaminopropyl) trimethoxysilane, 3-benzylaminopropyltrimethoxysilane, mercaptomethyltrimethoxysilane, γ-mercaptopropyltri Methoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, ali Triethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, 2- (3,4-epoxy And organoalkoxysilanes such as (cyclohexylethyl) trimethoxysilane and 2- (3,4-epoxycyclohexylethyl) triethoxysilane.

  These metal alkoxides can be used alone or in combination of two or more.

  The metal alkoxide is preferably tetramethoxysilane, tetraethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltrimethoxysilane. Examples include propoxysilane and methyltriisopropoxysilane.

  The hydrolysis condensate of a metal alkoxide can be obtained by hydrolyzing a metal alkoxide using a catalyst that promotes hydrolysis.

  Examples of the catalyst for promoting the hydrolysis of the metal alkoxide include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, boric acid, and phosphoric acid, such as tartaric acid, maleic acid, acetic acid, citric acid, dodecyl succinic acid, hexahydrophthalic acid, Organic acids such as methyl nadic acid, pyromellitic acid, benzophenone tetracarboxylic acid, dichlorosuccinic acid, chlorendic acid, p-toluenesulfonic acid and their anhydrides, such as alcoholic potassium hydroxide, alcoholic sodium hydroxide, etc. Examples include alkali catalysts.

  These catalysts can be used alone or in combination of two or more.

  The blending ratio of the catalyst varies depending on the type of the catalyst and is 0.1 to 5.0 parts by mass with respect to 100 parts by mass of the metal alkoxide.

  In addition to the above-described metal alkoxide or its hydrolysis condensate, examples of the inorganic component include metal particles and inorganic particles (excluding metal alkoxide or its hydrolysis condensate).

  As the metal particles, metal (for example, strontium (Sr), barium (Ba), manganese (Mn), cobalt (Co), nickel (Ni), aluminum (Al), copper (Cu), iron (Fe), titanium (Ti), zinc (Zn), silicon (Si), zirconium (Zr), lead (Pb), tin (Sn), antimony (Sb), bismuth (Bi), silver (Ag), gold (Au), platinum (Pt), tungsten (W), tantalum (Ta), cerium (Ce), niobium (Nb), neodymium (Nd), indium (In), alnico alloy (alloy of Al, Ni, Co), rare earth cobalt metal Compound, Fe—Ni alloy, Co—Fe alloy, Fe—Si—Al alloy (Sendust) and the like.

Examples of the inorganic particles include layered particles such as graphite, clay mineral, swellable layered silicate, montmorillonite, transition metal chalcogenide, zirconium phosphate, sepiolite, and synthetic fluorine mica, for example, oxide particles of the above metals, for example, Magneto-plumbite type complex oxide (MO · 6Fe ₂ O ₃ (M = Ba, Sr, Pb)) containing the above metal, for example, magnetic material particles such as Ni—Zn ferrite, Nd—Fe—B ceramics, For example, light emitting material particles such as barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, lead zirconate, barium zirconate and composite dielectric material particles such as ZnS, CaS, ZnSe; _{Na 2 O-B 2 O 3} -SiO 2 based glass, glass such as quartz Material particles, for example, silicon oxide, silicon carbide, silicon nitride, aluminum nitride, boron nitride, boron carbide, titanium carbide, high-strength ceramic particles of tantalum carbide and the like; silsesquioxane, hollow silica particles, MgF _2, clay particles, And apatite particles.

  In addition, inorganic particles can be obtained as commercial products. Examples of such commercially available products include Snowtex series (silica oxide, manufactured by Nissan Chemical Industries), and organosilica series (silica oxide, manufactured by Nissan Chemical Industries). , Nano use series (zirconia oxide, manufactured by Nissan Chemical Co., Ltd.), alumina sol series (aluminum oxide, manufactured by Nissan Chemical Co., Ltd.), and the like.

  These inorganic components can be used alone or in combination of two or more.

  The shape of the inorganic component is not particularly limited, and examples thereof include a spherical shape and a layer shape, and include an indefinite shape.

  As for the size of the inorganic component, the particle diameter measured by the dynamic light scattering method is, for example, 2 nm to 100 μm, preferably 2 nm to 10 μm, more preferably 3 nm to 1 μm.

  If the particle diameter is less than the above range, the dispersibility may be inferior due to aggregation of the particles, while if it exceeds the above range, the dispersibility may be inferior due to sedimentation of the particles.

  In the second coating composition, the content ratio of the organic component and the inorganic component is such that the mass ratio of the organic component to the inorganic component is, for example, 1:99 to 99: 1, preferably 1:19 to 80: 1. Preferably, it is 1: 8 to 75: 1, more preferably 1: 7 to 70: 1.

  When the content ratio of the inorganic component is less than the above lower limit, for example, the strength and refractive index of the resulting film may be inferior, and when the content ratio of the inorganic component exceeds the above range, the obtained first 2 The viscosity of the coating composition may increase and handleability may be poor.

  When the inorganic component is metal particles and / or inorganic particles (metal alkoxide or hydrolysis condensate thereof), the content ratio of the inorganic component is, for example, with respect to 100 parts by mass of the total amount of the organic component and the inorganic component. It is 99 mass parts or less, Preferably, it is 80 mass parts or less, More preferably, it is 50 mass parts or less, for example, 10 mass parts or more.

  In addition, when a polymer of a monomer containing a urethane bond-containing diol (meth) acrylate compound is used as the organic component and a metal alkoxide or a hydrolysis condensate thereof is used as the inorganic component, the second coating is used. If necessary, the composition can be blended with a condensation catalyst that promotes the condensation of the polymer with the metal alkoxide or its hydrolysis condensate.

  Examples of the condensation catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, and boric acid, such as tartaric acid, acetic acid, maleic acid, succinic acid, dodecyl succinic acid, hexahydrophthalic acid, methyl nadic acid, pyromellitic acid, benzophenone tetra Examples thereof include organic acids such as carboxylic acid, dichlorosuccinic acid, chlorendic acid and p-toluenesulfonic acid and anhydrides thereof, for example, alkali catalysts such as alcoholic potassium hydroxide and alcoholic sodium hydroxide.

  These condensation catalysts can be used alone or in combination of two or more.

  The blending ratio of the condensation catalyst is, for example, 0.1 to 5 parts by mass with respect to 100 parts by mass of the total amount of the second coating composition.

  Further, the second coating composition may be a curing agent such as an aminoplast, a polyisocyanate compound, a blocked polyisocyanate compound, and an acid anhydride, for example, a viscosity modifier, a leveling agent, an antifoaming agent, an organic, if necessary. Color pigments, dyes, paints (including resin paints such as epoxy resins, fluororesins, polyester resins, urethane resins), antioxidants, UV absorbers, stabilizers, plasticizers, waxes, additive UV rays Known additives such as a stabilizer and a solvent for adjusting solubility can be contained.

  These additives can be used alone or in combination of two or more.

  The content ratio of the additive is not particularly limited, and is appropriately set according to the purpose and application.

  Specific examples of such a second coating composition include inorganic / organic hybrid compositions obtained by the formulations and methods described in International Publication Pamphlet WO 2007/062304 [0014] to [0043].

  And although mentioned later in detail, the 2nd coating layer 4 is formed from said 2nd coating composition.

The adhesion amount of the second coat layer 4 is, for example, 0.2 to 1.0 g / m ² , preferably 0.3 to 0.7 g / m ² .

  FIG. 2 is a process diagram showing a manufacturing method of the pipe shown in FIG.

  Below, the manufacturing method of the pipe shown in FIG. 1 is demonstrated with reference to FIG.

  In this method, first, a tube 2 is prepared as shown in FIG.

  Next, in this method, the first coating composition described above is applied to the inner surface of the tube 2 as shown in FIG.

  The coating method of the first coating composition is not particularly limited, and can be appropriately selected depending on the purpose and application thereof, for example, brush coating, spray coating, flow coating, and the like.

The coating amount of the first coating composition is not particularly limited, but the adhesion amount of the first coat layer 3 after drying is, for example, 1 to 5 g / m ² , preferably ² to 4 g / m ^2. Adjusted to

  In this method, the coated first coating composition is preheated (for example, 80 to 120 ° C.) as necessary, and then cured by heating to form the first coat layer 3 on the inner surface of the tube. To do.

  As heating temperature of a 1st coating composition, it is 300-500 degreeC, for example, Preferably, it is 320-355 degreeC.

  Next, in this method, as shown in FIG. 2C, the above-described second coating composition is applied to the surface of the first coat layer 3.

  The method for applying the second coating composition is not particularly limited, and can be appropriately selected depending on the purpose and application thereof, for example, brush coating, spray coating, flow coating, and the like.

The coating amount of the second coating composition is not particularly limited, but the adhesion amount of the second coat layer 4 after drying is, for example, 0.2 to 1.0 g / m ² , preferably 0.3 to 0. It is adjusted to be 7 g / m ² .

  In this method, the coated second coating composition is cured by heating to form the second coat layer 4 on the surface of the first coat layer 3.

  As heating temperature of a 2nd coating composition, it is 50-200 degreeC, for example, Preferably, it is 150-190 degreeC.

  Thereby, the pipe 1 is manufactured.

  In the pipe 1 and the manufacturing method thereof, the pipe 1 is formed from the second coating composition by heating at a relatively low temperature on the first coating layer 3 formed from the first coating composition by heating at a relatively high temperature. A second coat layer 4 is laminated.

  As such a pipe, for example, when the pipe 1 is manufactured without laminating the second coat layer 4 while laminating the first coat layer 3 in a plurality of layers (two layers), excellent corrosion resistance can be secured. Since the formation of one coat layer 3 requires high-temperature heating a plurality of times (twice), there is a problem that the cost increases.

  On the other hand, in the pipe 1 described above, one first coat layer 3 and one second coat layer 4 are formed.

  Therefore, the number of times of heating at the time of forming the first coat layer 3 can be reduced, and the cost can be reduced. In addition, in such a pipe 1 and its manufacturing method, when forming the 2nd coating layer 4, although the cost which heats a 2nd coating composition starts, since the heating temperature is comparatively low temperature, The cost can be reduced as compared with the case where two coat layers 3 are formed.

  Moreover, in such a pipe 1 and its manufacturing method, since the 1st 1st coat layer 3 and the 1st 2nd coat layer 4 are formed, while the 1st coat layer 3 is laminated | stacked two layers, Excellent corrosion resistance comparable to that of a pipe manufactured without laminating the two coat layers 4 can be ensured.

  FIG. 3 is a schematic cross-sectional view showing another embodiment of the pipe of the present invention.

  In the above description, one layer of the first coat layer 3 and one layer of the second coat layer 4 are laminated on the inner surface of the tube 2, but for example, two layers of the first coat layer 3 and One layer of the second coat layer 4 can be sequentially laminated.

  In such a case, although not shown in detail, for example, the first coating composition is applied to the inner surface of the tube 2 and is heated and dried under the above-described conditions, whereby the first coating layer of the first layer is formed. 3a is formed. Thereafter, the first coating composition is applied again to the surface of the first coat layer 3a, and is heated and dried to form the second first coat layer 3b.

In such a case, the adhesion amount of the first first coat layer 3a is, for example, 1 to 5 g / m ² , preferably 1 to 4 g / m ² , and the second first coat layer 3b. The adhesion amount is, for example, 1 to 5 g / m ² , preferably 1 to 4 g / m ² .

Further, the total adhesion amount of the first coating layer 3a and the second coating layer 3b is, for example, 2 to 6 g / m ² , preferably ^{2 to 4} g. / M ² .

  Next, in this method, the second coating composition 4 is formed by applying the second coating composition described above to the surface of the second first coating layer 3b and heating and drying under the above-described conditions. The Thereby, the pipe 1 is manufactured.

  In such a pipe 1 and its manufacturing method, the first coat layer 3 is laminated in two layers, and the second coat layer 4 is laminated on the surface thereof, so that the first coat layer 3 is laminated in two layers, As compared with a pipe manufactured without laminating the second coat layer 4, it is possible to ensure further superior corrosion resistance.

Production Example 1 <Preparation of First Coating Composition>
While stirring 18.9 g of deionized water, 3 parts by weight of γ-glycidoxypropyltrimethoxysilane and 0.6 g of orthoboric acid were gently added. After continuing stirring for 3 hours, an additional 29.2 g of deionized water was added to the mixture and an ethoxylated nonylphenol wetting agent (nenw) (nonionic wetting agent, molecular weight 396, specific gravity at 20/20 ° C. 1.0298). A wetting agent mixture containing 5 g and 1.5 g of another type of ethoxylated nonylphenol wetting agent (nonionic wetting agent, molecular weight 616, specific gravity at 20/20 ° C. of 1.057) was added.

  Next, 2 g of the silane (γ-glycidoxypropyltrimethoxysilane), 4.1 g of acetone and 0.7 g of 1-nitropropane were added to the mixture, and a zinc flake paste (zinc particle thickness: 0) was added. 0.1 to 0.5 μm, length in the longitudinal direction 80 μm) was added to 35.2 g.

  The total amount of all these ingredients was then ground for about 3 hours with a Cowles dissolver operating at about 960 revolutions per minute (rpm).

Thereafter, 0.4 g of sodium bistridecyl sulfosuccinate (anionic surfactant) was added while stirring the resulting micronized mixture for 1 hour, and then continued to mix overnight and aged for 6 days Then, an additional 2.9 g of γ-glycidoxypropyltrimethoxysilane was added with mixing. This obtained the 1st coating composition. In the first coating composition, the molar ratio of water: silane alkoxy group was 26.7: 1.
Production Example 2 <Preparation of Second Coating Composition>
To the eggplant-shaped flask, 6.60 g of (R, S) -1,2-isopropylideneglycerol and 1 mL of pyridine were added, and a dropping funnel and a calcium tube were attached.

  Weigh 7.37 g of methacryloyloxyethyl isocyanate (manufactured by Showa Denko KK), slowly drop methacryloyloxyethyl isocyanate slowly at room temperature under light shielding, and then react for 7 hours in an oil bath set at 50 ° C. It was. After completion of the reaction, pyridine and excess (R, S) -1,2-isopropylideneglycerol are distilled off under reduced pressure to give (R, S) -1,2-isopropylideneglycerol-3-methacryloyloxy as a white solid. 12.7 g of ethyl urethane was obtained.

  Thereafter, a magnetic stirrer was placed in the screw tube, and 1.0 g of synthesized (R, S) -1,2-isopropylideneglycerol-3-methacryloyloxyethylurethane, 3.9 mL of methanol and 100 μL of 4N hydrochloric acid were added, and Under stirring for 30 minutes, the mixture was allowed to react, and the suspension became a clear solution. The mixture was further stirred for 60 minutes, reacted, and then dried under reduced pressure to obtain 852 mg of colorless viscous liquid glycerol-1-methacryloyloxyethylurethane (abbreviated as GLYMOU).

  By repeating the above reaction, 990 mg of GLYMOU was produced, and 990 mg of the obtained GLYMOU and 0.01 g of N-methylolacrylamide (crosslinkable monomer) were mixed to obtain a polymerizable raw material. 1 g of this polymerizable raw material, 5 mL of ethanol / water mixed solvent (4/1 (v / v)) and 2,2-azobisisobutyronitrile (1% by mass with respect to the total monomers) Weighed and mixed uniformly, and the inside of the test tube was replaced with nitrogen gas.

  Then, it was sealed and reacted at 70 ° C. for 24 hours to obtain 0.95 g of a polymer containing a glycerol-1-methacryloyloxyethylurethane: N-methylolacrylamide copolymer having a weight average molecular weight of 51,000.

  Next, 0.4 g of the obtained polymer was weighed, and 2 g of a methanol / water mixed solvent (4/1 (v / v)) was added and dissolved to obtain a polymer solution.

  On the other hand, 7.32 g of water, 6.52 mg of phosphoric acid and 910 mg of methanol were added to 4.23 g of tetraethoxysilane, and the mixture was stirred at 40 ° C. for 4 hours and hydrolyzed to obtain 12.5 g of a metal alkoxide hydrolysis condensate solution. Got.

Thereafter, 1.2 g of the polymer solution and 650 mg of the metal alkoxide hydrolysis condensate solution were mixed so that the mass ratio of the polymer and tetraethoxysilane was polymer: tetraethoxysilane = 48: 52. Thus, a second coating composition was obtained.
Example 1 <First coat layer 1 layer / Second coat layer 1 layer>
The first coating composition obtained in Production Example 1 is uniformly applied to the inner surface of an iron tube (thickness 0.7 mm, inner diameter 10.0 mm) using a centrifugal shaker, and preheated at 100 ° C. for 15 Then, the mixture was heated at 340 ° C. for 40 minutes to be cured. As a result, a first coat layer having an adhesion amount of 3.2 g / m ² was formed.

Next, the second coating composition obtained in Production Example 2 was uniformly applied to the surface of the formed first coat layer using a centrifugal shaker and heated at 180 ° C. for 25 minutes to be cured. . As a result, a second coat layer having an adhesion amount of 0.5 g / m ² was formed.

As a result, a pipe having one first coat layer and one second coat layer was obtained.
Example 2 <first coat layer 2 layers / second coat layer 1 layer>
The first coating composition obtained in Production Example 1 is uniformly applied to the inner surface of an iron tube (thickness 0.7 mm, inner diameter 10.0 mm) using a centrifugal shaker and heated at 340 ° C. for 40 minutes. And cured. As a result, a first coat layer (first layer) having an adhesion amount of 1.4 g / m ² was formed.

Next, the first coating composition obtained in Production Example 1 is again uniformly applied to the surface of the formed first coating layer (first layer) using a centrifugal shaker, and the coating is applied at 40 ° C. at 40 ° C. Heated for minutes and allowed to cure. As a result, a first coat layer having an adhesion amount of 1.5 g / m ² was formed.

Next, the second coating composition obtained in Production Example 2 is uniformly applied to the surface of the formed first coat layer (second layer) using a centrifugal shaker and heated at 180 ° C. for 25 minutes. And cured. As a result, a second coat layer having an adhesion amount of 0.5 g / m ² was formed.

Thereby, a pipe provided with two first coat layers and one second coat layer was obtained.
Comparative Example 1 <1 first coat layer / no second coat layer>
Except that the second coat layer was not formed, a pipe without the second coat layer was obtained in the same manner as in Example 2 while having the two first coat layers.

Evaluation Test pieces corresponding to Examples 1 and 2 and Comparative Example 1 were produced in the same manner as in Examples 1 and 2 and Comparative Example 1, except that an iron plate was used instead of the iron pipe.

  The surface of the obtained test piece on which the first coat layer and the second coat layer were formed was sprayed with salt water according to JIS H 8502 (1999) 8.1 neutral salt spray cycle test method. The spraying time was 100 cycles.

  Thereafter, the corroded material was removed with acid, and the thickness (minimum thickness) of the corroded portion was measured to determine the depth of corrosion.

  Corrosion resistance was evaluated by obtaining the corrosion depth (relative depth) of the test pieces corresponding to Examples 1 and 2 when the corrosion depth of the test piece corresponding to Comparative Example 1 was 1. The results are shown in Table 1.

  From Table 1, in the test piece of Example 1 in which one first coat layer and one second coat layer are formed, two first coat layers are formed, while the second coat layer is It turns out that it has the corrosion resistance comparable as the test piece of the comparative example 1 which is not formed.

  In addition, since the first coat layer is formed by heating the first coating composition at a relatively high temperature, the test piece of Example 1 having a small number of first coat layers is the same as that of Comparative Example 1 having a large number of first coat layers. Compared to the test piece, it could be manufactured at a low cost. In addition, in the test piece of Example 1, when the second coating layer is formed, the cost of heating the second coating composition is high, but since the heating temperature is relatively low, the first coating layer is Compared with the case of forming two layers, the cost can be reduced.

  Furthermore, from Table 1, the first coat layer is laminated in two layers, and the test piece of Example 2 in which the second coat layer is laminated on the surface of the first coat layer is laminated in two layers. It was confirmed that the test piece of Comparative Example 1 manufactured without laminating the coat layer was provided with further superior corrosion resistance.

1 pipe 2 pipe 3 first coat layer 4 second coat layer

Claims (2)

Tube,
A first coat layer formed on the inner surface of the tube;
A second coat layer formed on the surface of the first coat layer,
The first coating layer is formed from a first coating composition containing water, an organic solvent, a particulate metal, a silane binder and a wetting agent;
The second coat layer is an organic component containing a monomer containing a urethane bond-containing diol (meth) acrylate compound represented by the following general formula (1) or a polymer obtained by polymerizing the monomer, and A pipe formed from a second coating composition containing an inorganic component.

(Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkylene group having 1 to 4 carbon atoms.) Preparing a tube;
A first coating composition containing water, an organic solvent, a particulate metal, a silane binder and a wetting agent is applied to the inner surface of the tube and heated to 300-500 ° C., whereby the first coating composition is applied to the inner surface of the tube. Forming a coat layer;
An organic component containing a monomer containing a urethane bond-containing diol (meth) acrylate compound represented by the following general formula (1) or a polymer obtained by polymerizing the monomer, and an inorganic component containing an inorganic component 2 coating composition on the surface of the first coat layer, and heating to 50-200 ° C. to form a second coat layer on the surface of the first coat layer. And a method of manufacturing a pipe.

(Wherein R1 represents a hydrogen atom or a methyl group, and R2 represents a linear alkylene group having 1 to 4 carbon atoms.)

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