JPS6249116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to precoated metals. Generally, precoated metal is manufactured by applying paint to a metal plate and curing it by heating.
Conventionally, aminoalkyd resins, melamine-cured acrylic polyols, or epoxy resins have been used as precoating paints. However,
It was found that these resins have poor processability (bending properties) of the coating film, and cracks occur in the coating film when bent at an angle of 90° or more. In view of these circumstances, the present inventors conducted extensive research and found that, among known organic polyisocyanates, bis(isocyanatomethyl)cyclohexane compositions blocked with a specific blocking agent have improved processability (bending and bending). found that it is possible to provide a pre-coated metal that has a coating film with good hardness, stain resistance, and chemical resistance.
Based on this knowledge, we have completed the present invention. That is, the present invention provides a metal plate containing a composition containing bis(isocyanatomethyl)cyclohexane or its adduct (A) blocked with an oxime-based blocking agent or a lactam-based blocking agent and a polyol resin (B). The present invention relates to a pre-coated metal, characterized in that it is coated on a metal and cured by heating. Bis(isocyanatomethyl)cyclohexane used in the present invention includes, for example, 1,2-bis(isocyanatomethyl)cyclohexane, 1,3-bis(isocyanatomethyl)cyclohexane,
Examples include cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, and mixtures thereof. Examples of adducts of bis(isocyanatomethyl)cyclohexane include excess of the above-mentioned isocyanate and, for example, ethylene glycol, propylene glycol, 1,3-butylene glycol,
1,4-butylene glycol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, hexamethylene glycol, cyclohexanedimethanol, cyclohexanediol, trimethylolethane, trimethylolpropane, glycerin, hexanetriol, It is obtained by reacting with low molecular weight polyols such as hydrogenated bisphenol A, sorbitol, sorbitol, sucrose, pentaerythritol, and quadrol, or with high molecular weight polyols with a molecular weight of 500 to 3000 such as polyester polyols, polyether polyols, and epoxy resins. For example, a urethanized product obtained by reacting water, a lower amine such as ethylenediamine, and an excess of bis(isocyanatomethyl)cyclohexane, or a urethanized product obtained by reacting water, a lower amine such as ethylenediamine, and an excess of bis(isocyanatomethyl)cyclohexane, or the above-mentioned low-molecular-weight polyol or high-molecular-weight polyol and an excess of bis(isocyanatomethyl)cyclohexane. Examples include allophanate compounds obtained by reacting with. Even when the above-mentioned urethane compound, binder compound or allophanate compound contains a large amount of bis(isocyanatomethyl)cyclohexane monomer, it can be used in the present invention without removing it. The blocking agents used in the present invention include oxime-based and lactam-based ones. Specific examples of blocking agents include the following. Lactam blocking agents: ε-caprolactam, δ-valerolactam, γ
-butyrolactam, β-propiolactam, etc. Oxime blocking agents: formamidoxime, acetaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexanone oxime, etc. The blocked product (A) used in the present invention is obtained by reacting bis(isocyanatomethyl)cyclohexane or its adduct with the above blocking agent at an equivalent ratio of NCO/blocking agent = about 0.9 to 1.0, preferably about 0.95 to 1.0. The means for
NCO/blocking agent = about 1.1-3.0, preferably about
After reacting at an equivalent ratio of 1.2 to 2.0, a means for reacting the above-mentioned low molecular polyol, high molecular polyol, water or lower amine, bis(isocyanatomethyl)cyclohexane and low molecular polyol, high molecular polyol, Water or lower amine with NCO/active hydrogen = about 1.5 to 10.0, preferably about
It can be obtained by reacting at an equivalent ratio of 2.0 to 7.0 and then reacting with a blocking agent. Each of the above reactions can be carried out in a solvent that does not have an active hydrogen group (e.g. ester type such as ethyl acetate, butyl acetate, ketone type such as acetone, methyl ethyl ketone, methyl isobutyl ketone, ether type such as tetrahydrofuran) or This is carried out by a known method in the absence of a suitable solvent. In the reaction, known catalysts such as tertiary amines and organic metals may be used. Examples of the polyol resin (B) used in the present invention include polyester resins, acrylic polyol resins, and mixtures thereof. Examples of the polyester resin include polybasic acids such as phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and trimethic acid, and polybasic acids such as ethylene glycol, diethylene glycol, propylene glycol, Dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, hexamethylene glycol, decamethylene glycol, hydroquinone bis(hydroxyethyl ether), 2,2,4 −
Trimethyl-1,3-pentanediol, hydrogenated bisphenol A, tromethylolethane, trimethylolpropane, hexanetriol, glycerin, pentaerythritol, tris(hydroxyethyl)isocyanurate, cyclohexanediol, cyclohexanedimethanol, xylylene glycol, It can be obtained by condensing polyols such as quadrol by a conventional method under conditions with an excess of hydroxyl groups. In this case, it is also possible to use two or more types of acids or polyols in combination. Also, castor oil, higher fatty acids, etc. may be used in combination to form a so-called oil-modified polyester polyol. The polyester resin obtained by combining the above raw materials has a molecular weight of about 500 to 20,000, preferably about
2000-10000, hydroxyl value about 10-300, preferably about
20 to 200, acid value of about 1 to 50, preferably about 2 to 20. Examples of acrylic polyol resins include (1)
2-hydroxyethyl acrylate, acrylic acid 2
-hydroxypropyl, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, allyl alcohol, cinnamon alcohol, crotonyl alcohol or e.g. acrylic acid,
Unsaturated carboxylic acids such as methacrylic acid, maleic acid, fumaric acid, crotonic acid, and itaconic acid, such as ethylene glycol, ethylene oxide, propylene glycol, propylene oxide, butylene glycol, 1,4-cyclohexyl dimethanol, phenyl glycidyl ether, A hydroxyl group-containing monomer which is a reaction product with glycidyl decanoate etc. (2) such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-acrylate Acrylic esters such as butyl, 2-ethylhexyl acrylate, such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate,
Methacrylic acid esters such as n-butyl methacrylate, tert-butyl methacrylate, and 2-ethylhexyl methacrylate; styrenic monomers such as styrene, vinyltoluene, and α-methylstyrene; other acrylic acid, methacrylic acid, and acetic acid Vinyl, vinyl propionate, acrylonitrile, vinyl stearate, allyl acetate, diallyl adipate, dimethyl itaconate, diethyl maleate, vinyl chloride, vinylidene chloride, ethylene, glycidyl methacrylate, N-methyl-
Examples include those obtained by copolymerizing one or more types of copolymerizable α/β-ethylenically unsaturated monomers such as polyacrylamide, N-butoxymethylacrylamide, acrylamide, and diacetone acrylamide. . The acrylic polyol resin obtained by combining the above raw materials has a molecular weight of about 5,000 to 100,000, preferably about 10,000 to 50,000, a hydroxyl value of about 10 to 300,
Preferably, about 20 to 200 is used. In the present invention, first, this polyol resin (B)
A composition containing the block compound (A) and the block compound (A) is applied to a metal plate. Polyol resin (B) and blocked products
The blending ratio with (A) is adjusted so that the equivalent ratio of the recycled isocyanate groups of the blocked product (A) to the hydroxyl groups of the polyol resin (B) is about 0.5 to 2.0, preferably about 0.5 to 1.5. In addition to the blocked product (A) and the polyol resin (B), this composition also contains ester types such as ethyl acetate, butyl acetate, methyl acetoacetate, 2-ethoxyethyl acetate, aromatic types such as xylene and toluene, methyl ethyl ketone, Organic solvents such as ketones such as methyl isobutyl ketone and cyclohexanone, and ethers such as diethylene glycol dimethyl ether, those having an isocyanate group at the end such as bis(isocyanatomethyl)cyclohexane, etc., such as pigments, leveling agents, antifoaming agents , a dissociation catalyst, a stabilizer, and the like. The amount of the organic solvent is about 0 to 90% by weight based on the solid content of the blocked product (A) and the polyol resin (B). In addition, if it contains a substance having an isocyanate group at the terminal such as bis(isocyanatomethyl)cyclohexane, the amount is the same as that of the blocked product (A) and the polyol resin (B).
The amount is about 0.1 to 5% by weight based on the solid content. The metal plate used in the present invention may be any metal as long as it is normally used as a metal for pre-coated metal, such as aluminum, chin-free steel, galvanized iron plate, iron plate, etc. For example, phosphate-treated metal plate may be used. It is preferable to use chemical surface treatments such as The shape of the metal plate may be, for example, flat or cylindrical. The amount applied is approximately 10% by dry weight.
About g/m ² to 30 g/m ² is preferable. Examples of the coating means include a spray gun, a roll coater, a flow coater, and the like. Next, in the present invention, a metal plate coated with a composition containing a blocked product (A) and a polyol resin (B) is heated and cured. The heating temperature varies depending on the type of blocking agent, but it is approximately 150 to 350 degrees Celsius, and the heating time is approximately 20 seconds to 120 degrees Celsius.
About seconds is preferable. By this heating operation, crosslinking occurs due to the reaction between the blocked isocyanate in the blocked product (A) and the hydroxyl group in the polyol resin (B), resulting in a tough coating film. This coating shows no signs of fading or thermal deterioration due to heating operations, and has high hardness, workability (bending ability), stain resistance, and
Since both have good chemical resistance, the precoated metal obtained by the present invention can be advantageously used for building materials such as colored galvanized iron, for example, and for electrical appliances such as refrigerators and vending machines. The present invention will be explained in more detail below using Examples. In the examples, parts and % indicate parts by weight and % by weight, respectively. Example 1 581.5 parts of isophthalic acid, 707.9 parts of sebacic acid, 624.9 parts of neopentyl glycol, and 124.1 parts of ethylene glycol were heated to 220°C, nitrous gas was blown in, and the resulting water was distilled off while reacting to determine the acid value.
2.4, a polyester polyol resin having a hydroxyl value of 55 was obtained. This resin was dissolved in a mixed solvent of equal amounts of xylene and cyclohexanone to form a solution with a solid content of 40%. On the other hand, 1,3-bis(isocyanatomethyl)
Mix 582.6 parts of cyclohexane with 326 parts of ethyl acetate and 326 parts of ethoxyethyl acetate and heat to 75-80°C. Add 134.1 parts of melted trimethylolpropane while maintaining this temperature, and heat to 75-80℃ for 5 minutes.
Allow time to react. Then methyl ethyl ketoxime
261.3 parts were added dropwise over 1 hour, and after the addition was completed, the mixture was further heated to 75-80°C for 1 hour. In this way, a blocked polyisocyanate solution with a regenerated isocyanate group content of 7.7% and a solid content of 60% was obtained. 2550 parts of the above polyester polyol resin and 898 parts of titanium oxide (Thaibake R-930: Ishihara Sangyo) were kneaded and further 1,1,3,3-tetra-butyl-
2 parts of 1,3-diacetoxydistanoxane and 545 parts of the above blocked polyisocyanate solution were mixed and a dry film thickness of 20 mm was coated on a surface-treated galvanized iron plate with a thickness of 0.3 mm.
A glossy white paint film was obtained by spray painting it to a μm and baking it for 60 seconds in an atmosphere of 280°C. The coating film performance is shown in Table 1. Comparative Example 1 504.6 parts of hexamethylene diisocyanate was mixed with 300 parts of ethyl acetate and 300 parts of ethoxyethyl acetate.
Dissolve in 1 part and heat to 75-80℃. 134.1 parts of molten trimethylolpropane is slowly added dropwise while maintaining this temperature. Another 5 hours after the completion of dripping75
Heat to ~80°C. Then methyl ethyl ketoxime
261.3 parts were added dropwise over 1 hour, and after the addition was completed, the mixture was further heated to 75-80°C for 1 hour. In this way, a blocked isocyanate solution with a regenerated isocyanate group content of 8.4% and a solid content of 60% was obtained. 2550 parts of polyester polyol resin (same as Example 1) and 880 parts of titanium oxide (same as Example 1) were kneaded, and further 1,1,3,3-tetra-n-butyl-1,3-diacetoxydistanoxane Mix 1.5 parts and 500 parts of the above block polyisocyanate solution to form a 0.3 mm
A glossy white coating was obtained by coating a thick surface-treated galvanized iron plate to a dry film thickness of 20 μm and baking it for 60 seconds in an atmosphere of 280°C. The coating film performance is shown in Table 1. Comparative Example 2 666.9 parts of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate was mixed with 354.1 parts of ethyl acetate and ethoxyethyl acetate.
Dissolve in 354.1 parts and heat to 75-80℃. 1・
After adding 0.2 parts of 1,3,3-tetra-n-butyl-1,3-diacetoxydistanoxane, 134.1 parts of molten trimethylolpropane was added dropwise over 1 hour. 75-80℃ for another 5 hours after completion of dripping
Heat to. Then methyl ethyl ketoxime 261.3
portion was added dropwise over 1 hour. After the addition is complete, the mixture is further heated to 75-80°C for 1 hour. In this way, a blocked polyisocyanate solution with a regenerated isocyanate group content of 7.1% and a solid content of 60% was obtained. 2,550 parts of polyester polyol resin (same as Example 1) and 916 parts of titanium oxide (same as Example 1) were kneaded, and 1,1,3,3-tetra-n-butyl-1,3-diacetoxydistano Mix 2 parts of xane and 590 parts of the above blocked polyisocyanate solution, apply the mixture to a surface-treated galvanized iron plate with a thickness of 0.3 mm to a dry film thickness of 20 μm, and bake it in an atmosphere of 280°C for 60 seconds to create a glossy finish. A white coating was obtained. The coating film performance is shown in Table 1. Example 2 233 parts of 1,4-bis(isocyanatomethyl)cyclohexane was dissolved in 375 parts of ethoxyethyl acetate, and methyl ethyl ketoxime was added to this solution.
Gradually drip 174.2 parts. 75-80℃ after completion of dripping
Heat for 1 hour. Next, 155.2 parts of polytetramethylene ether glycol having a molecular weight of 620 and 0.7 parts of dibutyltin dilaurate are added and reacted at 75 to 80°C for 5 hours. Thus, the recycled isocyanate group content
A blocked polyisocyanate solution having a solid content of 8.5% and a solid content of 60% was obtained. 2550 parts of polyester polyol resin (same as in Example 1) and 878 parts of titanium oxide (same as in Example 1) were kneaded, and further 1.1.3.3-
1.5 parts of tetra-n-butyl-1,3-diacetoxydistanoxane and 494 parts of the above block polyisocyanate solution were mixed and spray-painted on a surface-treated galvanized iron plate with a thickness of 0.3 mm to a dry film thickness of 20μ. When baked in an atmosphere of 280℃ for 60 seconds, a glossy white coating was obtained. The coating film performance is shown in Table 1. Example 3 700 parts of methyl methacrylate, 207 parts of n-butyl acrylate, and 93 parts of 2-hydroxyethyl methacrylate were copolymerized in 250 parts of xylene and 250 parts of butyl acetate by a conventional method to obtain a product with a molecular weight of about 15,000 and a solid content of 50%. An acrylic polyol resin with a hydroxyl value of 20 was obtained. Separately, 116.5 parts of 1,3-bis(isocyanatomethyl)cyclohexane was dissolved in 156.1 parts of ethoxyethyl acetate, and 87.1 parts of methyl ethyl ketoxime was added dropwise over 1 hour. After the addition is complete, the mixture is further heated to 75-80°C for 1 hour. Next, 0.38 parts of dibutyltin dilaurate and oil-modified polyester polyol (444 parts of phthalic anhydride, coconut oil fatty acid)
200 parts of propylene glycol, 152 parts of propylene glycol, and 268 parts of trimethylolpropane are condensed using a conventional method, and the resulting resin is made into a 70% solution of butyl acetate. acid value
4.0, hydroxyl value 115) add 122 parts of solution, 75-80
React at ℃ for 4 hours. In this way, a blocked polyisocyanate solution with a regenerated isocyanate group content of 8.3% and a solid content of 60% was obtained. 2,800 parts of the above acrylic polyol resin and 1,137 parts of titanium oxide (same as in Example 1) were kneaded and 1.1.
Mix 1.5 parts of 3,3-tetrabutyl-1,3-diacetoxydistanoxane and 508 parts of the above block polyisocyanate solution, and spray paint on a 0.3 mm thick surface-treated galvanized iron plate to a dry film thickness of 20μ. When baked for 60 seconds at 280°C, a glossy white coating was obtained. The coating film performance is shown in Table 1. Comparative Example 3 157.4 parts of 4,4'-methylenebis(cyclohexyl isocyanate) was converted into ethoxyethyl acetate.
Dissolved in 183.3 parts methyl ethyl ketoxime 87.1 parts
1 hour. Another 1 hour after completion of dripping
Heat to 75-80°C. Next, 0.44 parts of dibutyltin dilaurate and 122 parts of an oil-modified polyester resin solution (same as in Example 3) are added and reacted at 75-80°C for 6 hours. Thus the regenerated isocyanate group content is 7.3
%, a blocked polyisocyanate solution with a solid content of 60% was obtained. 2800 parts of acrylic polyol resin (same as Example 3) and titanium oxide (same as Example 1)
1,165 parts of 1,1,3,3-tetra-n-butyl-1,3-diacetoxydistanoxane were mixed and 1.7
Part and the above blocked polyisocyanate solution 579
A glossy white paint film was obtained by mixing the two parts and coating it on a 0.3 mm thick surface-treated galvanized iron plate to a dry film thickness of 20 μm and baking it in an atmosphere of 280°C for 60 seconds. The coating film performance is shown in Table 1. Example 4 361.2 parts of 1,3-bis(isocyanatomethyl)cyclohexane was converted into ethoxyethyl acetate.
Dissolved in 474.9 parts dibutyltin dilaurate 1.26
After adding 50% of the reaction mixture, molten ε-caprolactam is slowly added dropwise so that the temperature of the reaction mixture becomes 70 to 75°C. After the addition is complete, the mixture is further heated to 75-80°C for 2 hours. Next, polyester polyol resin (obtained by condensing 876.6 parts of adipic acid, 186.3 parts of ethylene glycol, 201.2 parts of trimethylolpropane, and 402.3 parts of dipropylene glycol, acid value 3.5, hydroxyl value 172, solid content 100%) Add 239 parts and heat to 75-80°C for 5 hours. In this way, a blocked polyisocyanate solution with a regenerated isocyanate group content of 7.8% and a solid content of 60% was obtained. 2550 parts of polyester polyol resin (same as Example 1) and 895 parts of titanium oxide (same as Example 1) were kneaded,
1.6 parts of 1,1,3,3-tetra-n-butyl-1,3-diacetoxydistanoxane and 538 parts of the above block polyisocyanate solution were mixed, and a dry film thickness of 0.3 mm thick surface-treated galvanized iron plate was obtained. When spray-painted to a thickness of 20μ and baked for 60 seconds at 280℃, a glossy white coating was obtained. The coating film performance is shown in Table 1. 【table】

Claims (1)

[Claims] 1. A composition comprising bis(isocyanatomethyl)cyclohexane or its adduct (A) blocked with an oxime-based blocking agent or a lactam-based blocking agent and a polyol resin (B). Pre-coated metal is characterized by being coated onto a metal plate and hardened by heating. 2. The precoated metal according to claim 1, wherein the composition containing component (A) and component (B) further contains bis(isocyanatomethyl)cyclohexane.