JP2010194409A - Coating method in car coating line - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating method in a car coating line, in which a chipping-resistant coating material stuck to an unintended portion can be removed easily without increasing a baking step and a subsequent step of applying another coating material can be carried out in a wet state. <P>SOLUTION: An ultraviolet-curable resin composition, which contains 100 pts.mass of an acrylic resin or vinyl chloride resin and 15-150 pts.mass of a reactive acrylate oligomer, is applied to a predetermined portion of the body of a car by a spray. The applied ultraviolet-curable resin composition is cured by irradiating the predetermined portion with ultraviolet rays. The ultraviolet-curable resin composition stuck to the portions other than the predetermined portion is removed. Both of the ultraviolet-curable resin composition-applied portion and the ultraviolet-curable resin composition-removed portion are recoated with another coating material in the wet state. The recoated coating material is baked/cured together with the ultraviolet-curable resin composition. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coating method in an automobile production line in which a paint is applied on an ultraviolet curable resin composition applied to a car rocker panel, a door lower part, a fender and the like for protecting a vehicle body.

Generally, compositions applied for the purpose of anti-chipping of automobiles include those based on vinyl chloride resins and those based on acrylic resins that have begun to be used as alternatives.
These chipping-resistant materials are usually applied directly to the electrodeposition plate that constitutes the automobile body by spraying, and then applied by laminating an intermediate paint, base paint, clear paint, etc., and baking and curing. Let
In the above process, if the spray dust of the chipping-resistant material adheres to an unintended part, it becomes a protrusion to the paint applied later on the part or the paint applied later is exposed, resulting in the exposure of the groundwork. A bad appearance of the paint, such as, is a serious problem.

For this reason, in a conventional automobile painting line, after spraying a chipping-resistant material, the chipping-resistant paint adhering to an unintended part is wiped off, and an intermediate paint is applied thereon.
However, since the conventional chipping-resistant paint was wiped off in an undried state, there was a problem that wiping residue was generated in a stretched state on the adherend surface.
In addition, after leaving the wiping residue of the chipping-resistant paint, after applying the intermediate paint from the top, after baking and curing these, the protrusions produced on the painted surface are scraped with sandpaper or the base is exposed For this reason, a portion that is recessed with respect to the other intermediate coating portion is smoothed by sandpaper, and the top coating material is applied thereon, so that there is a problem that the coating efficiency in the coating line is very poor.

On the other hand, for the purpose of shortening the process of automobile painting lines and reducing oven fuel and CO ₂ recently, intermediate coating, base coating and There is a tendency for 3WET lines to be baked only once after the clear paints are sequentially laminated and applied in a wet state (see, for example, Patent Document 1).
In the case of such a 3WET line, the baking and the subsequent smooth finish performed after the conventional intermediate coating is applied cannot be performed. Therefore, it is necessary to completely remove the chipping-resistant coating with only a dust wipe.
However, the dust generated by spraying is easy to miss when visually discriminating because the droplet size is small, and conversely, depending on the way of wiping, the sol-like chipping resistant paint is stretched to form a streak. The area that repels the paint applied from above is widened, which is a problem when the 3WET line is introduced.

In order to solve this problem in introducing the 3WET line, a method of curing with a calcining furnace before applying another paint on the chipping resistant paint can be considered, but this introduces the 3WET line. Therefore, the purpose of shortening the painting line and reducing the fuel for the oven, which is the original purpose, is not achieved.
Further, when the chipping-resistant paint is baked at a high baking temperature, there is a problem that dust that needs to be wiped adheres to the adherend surface and cannot be sufficiently wiped off with a cloth or the like. Further, when the chipping resistant paint is baked at a low baking temperature, there is a problem that a fine residue of clay-like dust remains.

JP 2007-83201 A

  Therefore, in order to solve the above problems, the present invention can remove the anti-chipping paint adhering to an unintended part without increasing the baking process, and the subsequent coating process of other paints in a wet state. It is an object of the present invention to provide a painting method in an automobile painting line that can be performed.

In order to solve the above-mentioned problem, the coating method in the automobile painting line of the present invention is as described in claim 1, wherein a predetermined part of the body of the automobile is provided for 100 parts by mass of acrylic resin or vinyl chloride resin. The ultraviolet curable resin composition containing 15 to 150 parts by mass of a reactive acrylate oligomer was applied by spraying, and the ultraviolet curable resin composition was cured by irradiating with ultraviolet rays, and then adhered to other than the predetermined part. The UV curable resin composition is removed, and another paint is applied in a wet state to both the site where the UV curable resin composition is applied and the site where the UV curable resin composition is removed. The other paint is baked and cured together with the ultraviolet curable resin.
Moreover, the present invention described in claim 2 is characterized in that, in the coating method in the automobile coating line according to claim 1, the ultraviolet curable resin composition is removed by wiping.
The present invention according to claim 3 is characterized in that, in the coating method for an automobile painting line according to claim 1 or 2, the other paint is an intermediate paint, a base paint, and a clear paint. .
According to a fourth aspect of the present invention, there is provided the coating method for an automobile painting line according to any one of the first to third aspects, wherein the ultraviolet curable resin composition is an acrylic resin or a vinyl chloride resin 100. It is characterized by containing 15 to 100 parts by mass of a reactive acrylate oligomer and 0.15 to 30 parts by mass of a polymerization initiator with respect to parts by mass.

  According to the present invention, since the composition is cured by ultraviolet irradiation, it is not stretched during wiping, and the ultraviolet curable resin composition is an adherend (electrodeposition) that is cured by ultraviolet irradiation. Since it is not in close contact with the plate, it can be easily wiped off. And 3WET coating can be efficiently performed by using this ultraviolet curable resin composition.

Table 1 showing evaluation of Examples and Comparative Examples

In the present invention, an ultraviolet curable resin composition containing 15 to 150 parts by mass of a reactive acrylate oligomer is applied to a predetermined part of an automobile body by spraying with respect to 100 parts by mass of an acrylic resin or a vinyl chloride resin. After the ultraviolet curable resin composition is cured by irradiating with ultraviolet rays, the ultraviolet curable resin composition adhered to other than the predetermined part is removed, and the part where the ultraviolet curable resin composition is applied and the ultraviolet ray are removed. The other paint is applied in a wet state to both the parts from which the cured resin composition has been removed, and the other paint is baked and cured together with the ultraviolet curable resin.
Examples of the member constituting the predetermined part of the vehicle body to which the ultraviolet curable resin composition is applied include an electrodeposition plate constituting the outer plate thereof. An ultraviolet curable resin composition is applied to the predetermined portion by spraying and then cured by irradiation with ultraviolet rays. In this state, the ultraviolet curable resin composition is not in close contact with a predetermined site because it does not cause a gelling reaction to take in a plasticizer such as a vinyl chloride resin or an acrylic resin. For this reason, the paint adhering to other than the predetermined part can be easily removed by wiping manually with a cloth or the like. Accordingly, a plurality of other paints can be laminated and applied in a wet state (a state where baking is not performed) on the predetermined portion from which the ultraviolet curable resin composition has been removed.

  The ultraviolet curable resin composition used in the present invention can be applied by spraying, contains 15 to 100 parts by weight of a reactive acrylate oligomer with respect to 100 parts by weight of an acrylic resin or vinyl chloride resin, and by ultraviolet light. If it contains a polymerization initiator so that it may harden | cure, it will not restrict | limit in particular.

  As the acrylic resin, for example, a single polymer or copolymer of a monomer selected from alkyl acrylate, alkyl methacrylate, and the like can be used. Specific examples of the monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, ter-butyl acrylate, cyclohexyl acrylate, benzyl acrylate, and methyl methacrylate. , Ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, ter-butyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate and the like. As the copolymer component, styrene, α-methylstyrene, methacrylic acid, acrylic acid, itaconic acid, crotonic acid, and the like can also be used.

The vinyl chloride resin includes (1) a vinyl chloride paste resin produced by emulsion polymerization of vinyl chloride alone or a comonomer copolymerizable with vinyl chloride in the presence of an emulsifier and a water-soluble polymerization initiator; or (2) Those produced by a fine suspension polymerization method in which vinyl chloride alone or a comonomer copolymerizable with vinyl chloride is mechanically finely dispersed and then polymerized in the presence of a dispersant and an oil-soluble polymerization initiator. Can be mentioned. In addition to these, a vinyl chloride resin having a relatively large particle size produced by ordinary suspension polymerization may be used in combination. Examples of the copolymerizable comonomer include vinyl esters such as vinyl acetate, vinyl propionate, and vinyl laurate; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and hydroxyethyl acrylate; methyl methacrylate, ethyl Methacrylic acid esters such as methacrylate and hydroxyethyl methacrylate; Maleic acid esters such as dibutyl maleate and diethyl maleate; Fumarate esters such as dibutyl fumarate and diethyl fumarate; Vinyl methyl ether, vinyl butyl ether, vinyl octyl ether Vinyl ethers such as acrylonitrile, methacrylonitrile, etc. vinyl cyanides; α-olefins such as ethylene, propylene, styrene, etc .; vinylidene chloride Or vinylidene halide or other vinyl halide such as vinyl bromide and the like, these one or more thereof, 30 wt% or less, preferably can be copolymerized with less than 20%.
The degree of polymerization is preferably 500 to 2500, preferably 850 to 2000, and more preferably 1200 to 1800, as a result of polymerizing the above vinyl chloride alone or a comonomer copolymerizable with vinyl chloride.

Examples of the polymerization initiator include benzoin, alkylphenone (benzyldimethyl ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, etc.), acylphosphine oxide (monoacylphosphine oxide, bisacylphosphine oxide). Etc.), sulfur compounds such as titanocene, oxime ester, oxyphenylacetate, tetramethylthiuram disulfide, etc. can be used.
This polymerization initiator is preferably contained in an amount of 0.15 to 30 parts by mass with respect to 100 parts by mass of the vinyl chloride resin or acrylic resin. When the amount is less than 0.15 parts by mass, ultraviolet curing becomes insufficient, and when it exceeds 30 parts by mass, a large amount of unreacted substances remain and the coating film performance is deteriorated.
Among the polymerization initiators, it is preferable to use an acyl phosphine oxide-based compound because it is necessary to cure to the deep part of the thick film with ultraviolet rays. Furthermore, it is preferable to mix an alkylphenone-based α-hydroxyalkylphenone compound with the acylphosphine oxide-based compound. This is because the polymerization efficiency can be improved and surface hardening can be promoted.
Furthermore, in order to increase the photopolymerization initiation efficiency, a photosensitizer may be used in combination. Examples of the photosensitizer include aromatic and aliphatic tertiary amines.

In addition, as the reactive acrylate oligomer, an oligomer having a molecular skeleton of urethane, ether, ester, epoxy, silicon or the like and an acryloyl group at the molecular end can be used, and among these, a polyester acrylate oligomer and a urethane acrylate oligomer In general, epoxy acrylate oligomers are used.
The polyester acrylate oligomer is obtained by reacting a terminal hydroxyl group of a polyester obtained from a dibasic acid and a diol with (meth) acrylic acid.
In the urethane acrylate oligomer, an acrylic monomer having a hydroxyl group, a diisocyanate, and a diol undergo an addition reaction to generate urethane having an acrylic double bond.
The epoxy acrylate oligomer is an epoxy resin obtained by addition reaction of (meth) acrylic acid.
The content of the oligomer is 15 to 100 parts by mass with respect to 100 parts by mass of the vinyl chloride resin or the acrylic resin. When the amount is less than 15 parts by mass, curing by ultraviolet rays is insufficient. When the amount exceeds 100 parts by mass, the molecular weight is higher than that of the monomer, so that the viscosity is high and the coating workability tends to be remarkably deteriorated.

In addition, about the application | coating conditions and hardening conditions of the ultraviolet curable resin composition of this invention, although it does not restrict | limit, if an example is given, application | coating conditions will be about 0.2-2 mm in film thickness, and normal temperature-40. in was coated approximately ° C., UV curing conditions ^may be the ^{1000mJ / cm 2 ~6000mJ / cm 2} .

  In addition to the essential components described above, a latent curing agent, an adhesive, a plasticizer, a filler, and the like may be included as necessary.

  Examples of the latent curing agent include polyamines and modified products, aromatic amines and modified products, hydrazides, etc., which are inactive at room temperature, but are particularly activated by heating and react with isocyanate. Any of them can be used, and it is preferable to contain 2.5 to 10 parts by mass with respect to 100 parts by mass of the acrylic resin.

Moreover, as an adhesive agent, a polyamidoamine or a blocked isocyanate-containing urethane prepolymer can be used. The blocked isocyanate-containing urethane prepolymer is obtained by blocking residual isocyanate of polyurethane obtained by reacting isocyanate and α-polyol such as polyether polyol and polyester polyol with a blocking agent.
In addition, it is preferable to use a block isocyanate-containing prepolymer in terms of stability with the reactive acrylate oligomer.

The blocked isocyanate-containing urethane prepolymer can be produced according to the following procedure.
First, a polyol and an excess polyisocyanate compound are reacted to obtain a terminal NCO-containing urethane prepolymer.
Examples of the polyol include polyoxyalkylene polyol (PPG), polyether polyol modified, polyether polyol containing polytetramethylene ether glycol; condensed polyester polyol, lactone polyester polyol, polyester polyol containing polycarbonate diol; Polyol; Polyolefin-based polyol; Acrylonitrile alone or a mixed monomer of acrylonitrile and at least one selected from the group of styrene, acrylamide, acrylic ester, methacrylic ester and vinyl acetate in the polyether polyol is polymerized or graft polymerized. And polymer polyols.

  Examples of the polyisocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, 1,3-cyclohexane. Pentane diisocyanate, 1,6-hexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate), methyl 2,4-cyclohexane diisocyanate, methyl 2,6- Cyclohexane diisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, 1,3-bis (isocyanatemethyl) cyclohexane, m-pheny Diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, crude MDI, 2,4- or 2,6-tolylene diisocyanate, 4,4 '-Toluidine diisocyanate, dianidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 1,3- or 1,4-xylylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, And dimer acid diisocyanate, ω, ω unit-diisocyanate-1,4-diethylbenzene, and the like.

Next, by reacting the terminal NCO-containing urethane prepolymer with an appropriate blocking agent to block free NCO, the target blocked isocyanate-containing urethane prepolymer is obtained.
Examples of the blocking agent include monohydric alcohols such as methanol, ethanol, propanol, butanol, isobutanol, isononyl alcohol, stearyl alcohol or isomers thereof; phenol, cresol, xylol, p-nitrophenol, alkylphenol, and the like. Phenols; Active methylene compounds such as methyl malonate, ethyl malonate, dimethyl malonate, diethyl malonate, ethyl acetoacetate, methyl acetoacetate, acetylacetone; acid amides such as acetamide, acrylamide, acetanilide; succinimide, malee Acid imides such as acid imides; imidazoles such as 2-ethylimidazole and 2-ethyl-4-methylimidazole; lactams such as 2-pyrrolidone and ε-caprolactam; acetoxime and methyl ethyl Ketone oxime, methyl isobutyl ketoxime, cyclohexanone oxime, ketone or aldehyde oximes such as acetaldoxime; glycol derivatives such as methyl glycol, ethyl glycol, ethyl diglycol, ethyl triglycol; amine compounds such as dicyclohexylamine, and other ethylene Examples include imine and bisulfite.
This adhesion agent is preferably contained in an amount of 15 to 150 parts by mass with respect to 100 parts by mass of the acrylic resin or vinyl chloride resin. If the amount is less than 15 parts by mass, the adhesion to the adherend is insufficient, and if it exceeds 150 parts by mass, the coating workability tends to be remarkably deteriorated.

As a plasticizer, well-known plasticizers, such as a phthalic acid ester, phosphoric acid ester, adipic acid ester, a sebacic acid ester type plasticizer, can be used, for example. For example, phthalate ester plasticizers include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dihexyl phthalate (DHP), di-2-ethylhexyl phthalate (DOP), diisodecyl phthalate (DIDP) , Butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), dinonyl phthalate (DNP), etc., and phosphate ester plasticizers such as tricresyl phosphate (TCP), trixylylene phosphate (TXP), adipic acid ester Examples of the plasticizer include dioctyl adipate (DOA) and diisodecyl adipate (DIDA), and examples of the sebacate ester plasticizer include dibutyl sebacate (DBS) and dioctyl sebacate (DOS). , It can be used alone or in combination of two or more of these one in particular phthalate-based plasticizer is preferable.
Since the plasticizer can be varied by adjusting the viscosity, the amount is not particularly specified. However, if the amount is too small, the elongation is lowered. If the amount is too large, the paint adhesion may be affected. Usually, it is adjusted to about ± 20% with respect to the basic amount of the plasticizer to be added.

  Examples of the filler include inorganic fillers such as calcium carbonate, barium sulfate, clay, diatomaceous earth, silica, and talc, and these can be used alone or in combination of two or more. Further, if necessary, hollow particles such as a glass balloon, a resin balloon, or a resin balloon that expands when heated can be blended.

  Moreover, as another coating material applied in a wet state from the top of the ultraviolet curable resin composition, either an intermediate coating material, a base coating material, or a clear coating material, or these are sequentially laminated and applied. In addition, about these coating materials, a well-known thing can be used.

Examples of the present invention will be described together with comparative examples, but the present invention is not limited thereby.
The following raw materials were used, and the ultraviolet curable resin composition of Examples 1-14 and Comparative Examples 1-4 was created by the mixing | blending shown by FIG.

[Combined raw materials]
(1) Acrylic resin: Acrylic powder for plastisol (Dianar LP-3106 manufactured by Mitsubishi Rayon Co., Ltd.)
(2) Vinyl chloride resin: (Tosoh Corporation Leuron paste 850)
(3) Reactive acrylate oligomer:
・ Epoxy acrylate oligomer (CN111US, manufactured by Sartomer)
・ Polyester acrylate oligomer (CN2300 manufactured by Sartomer)
・ Urethane acrylate oligomer (CN978, manufactured by Sartomer)
(4) Polymerization initiator: Acylphosphine oxide (Ciba Specialty Chemicals Co., Ltd. IRGACURE 819)
(5) Latent curing agent (powder): Polyamine type (EH3731S manufactured by Adeka Co., Ltd.)
(6) Adhesive agent: Blocked isocyanate-containing urethane prepolymer (Q9494 manufactured by Adeka Corporation)
(7) Filler, silica, calcium carbonate (8) Plasticizer, sulfonic acid polyester: (Mezzamol manufactured by LANXESS)
DINP: diisononyl phthalate (manufactured by J Plus Corporation)

Using the examples and comparative examples, an evaluation test was conducted under the following conditions, and the results are shown in Table 1 (FIG. 1).
(1) Curability: Each example was applied to a test piece made of an electrodeposited steel sheet of 10 cm × 10 cm with a film thickness of 2 mm, irradiated with ultraviolet rays, and then pressed with a finger to change the surface tack state and its deformation. Confirmed by finger touch. The evaluations in Table 1 are as follows: “◎” indicates “no surface tack, no deformation”, “◯” indicates “slight surface tack, no deformation”, “Δ” indicates “surface tack, no deformation”, “ "-" Is "uncured".
(2) Wipeability: After applying the composition of each example to a test piece made of an electrodeposited steel sheet of 10 cm × 30 cm with only dust by airless spray, each tag lag (Rusher adhesive dustless wiping cloth) )) The degree of wiping was confirmed. The evaluation in Table 1 is that “◎” is “easy to wipe off and there is no trace”, “○” is “wipe off when a little force is applied, there is no trace”, and “△” is “after wiping” Remains streaked. "
(3) Paintability after wiping: Apply the intermediate coating (first base), topcoat (second base), and clear to each test piece after the above wiping performance, and check the appearance after baking. did. In the above coating, after intermediate coating and top coating, preheating at 80 ° C. was performed for 3 minutes, and baking after clear coating was performed at 130 ° C. for 18 minutes. The film thickness during coating was 20 μm for the intermediate coating, 13 μm for the top coating, and 35 μm for clear. Further, in the evaluation in Table 1, “◯” indicates “no unevenness” and “Δ” indicates “with unevenness”.
(4) Nut drop performance: A test piece of 10 cm × 15 cm electrodeposited steel sheet was coated with the composition of each example at a film thickness of 300 μm, and after ultraviolet irradiation, coating and baking were performed in the same manner as in (3). . Each test piece is fixed to a table inclined at 60 °, and an M4 size nut is dropped on the test piece through a vinyl chloride pipe with a diameter of 20 mm from a height of 2 m until the electrodeposited steel plate surface is exposed. The weight was measured.
(5) Adhesion to water-resistant paint: A test piece of a 10 cm × 15 cm electrodeposited steel sheet was coated with the composition of each example at a film thickness of 300 μm, and after UV irradiation, painted and baked in the same manner as (3) It was.
Each test piece was immersed in warm water of 40 ° C., and coating adhesion after 10 days was confirmed by cross-cut peeling. In addition, grid cross-cutting was performed by making 11 cuts in a cross-cut pattern on the coating surface of each test piece, vertically and horizontally at 2 mm intervals to form 100 2 mm square coated pieces. The Nichiban industrial cellophane tape was stuck on the coated piece, and the number of pieces peeled off by abruptly peeling off one end of the tape was counted.
In addition, for the ultraviolet irradiation of the above (1), (4) and (5), “Iglandage ECS-401GX” manufactured by Eye Graphics was used, the output was 4 kW, and the distance to the object was 100 mm. .

From Table 1 above, the following can be understood.
(1) Curability Since Comparative Examples 1 and 2 do not contain a polymerization initiator, they do not cure even when irradiated with ultraviolet rays. In Comparative Examples 3 and 4, the content of reactive acrylate oligomer is acrylic resin or vinyl chloride. It is because it was less than 15 mass parts with respect to 100 mass parts of the system resin.
On the other hand, it was found that Examples 1 to 14 were all cured well.
(2) Wiping property Since Comparative Examples 1 and 2 were not cured, they extended to the adherend surface during wiping and could not be wiped off, and Comparative Examples 3 and 4 had a reactive acrylate oligomer content. Since the amount was less than 15 parts by mass with respect to 100 parts by mass of the acrylic resin or vinyl chloride resin, the ultraviolet curable resin composition remained on the adherend surface as in Comparative Examples 1 and 2.
On the other hand, in Examples 1-14, it turned out that the ultraviolet curable resin composition of the to-be-adhered surface was able to wipe off favorably.
(3) Paintability after wiping Since Comparative Examples 1 to 4 showed that the ultraviolet curable resin composition remained on the adherend surface of the ultraviolet curable resin composition, as can be seen from the results of (1) and (2) above. Then, when another coating was applied, irregularities due to unwiping of the UV curable resin composition appeared on the surface of the other coating.
On the other hand, in Examples 1 to 14, since the ultraviolet curable resin composition was sufficiently wiped off, irregularities due to unwiping of the ultraviolet curable resin composition appeared on the surface of the other paint.
(4) Nut dropping performance In Examples 1 to 14 and Comparative Examples 1 to 4, the target nut weight was 20 kg or more, but the reactive acrylate oligomer exceeded 150 parts by mass as in Comparative Examples 5 and 6. Was confirmed to be less than 20 kg.
(5) Adhesion to water-resistant paint In Examples 1 to 14 and Comparative Examples 1 to 4, the target peeling was 0, but the reactive acrylate oligomer exceeded 150 parts by mass as in Comparative Examples 5 and 6. It was confirmed that the adhesiveness was inferior and peeled off.

  The coating method of the present invention can be widely used for structures such as automobiles to improve the appearance of coating on the 3WET line, which is expected to increase in the future.

Claims (4)

  An ultraviolet curable resin composition containing 15 to 150 parts by mass of a reactive acrylate oligomer is applied to a predetermined part of an automobile body with 100 parts by mass of an acrylic resin or a vinyl chloride resin by spraying, and the ultraviolet curing is performed. After the resin composition is cured by irradiating with ultraviolet rays, the ultraviolet curable resin composition adhering to other than the predetermined part is removed, and the part where the ultraviolet curable resin composition is applied and the ultraviolet curable resin composition A coating method in an automobile painting line, wherein another part of the paint is applied in a wet state to both parts of the part from which the resin has been removed, and the other paint is baked and cured together with the ultraviolet curable resin.   The said ultraviolet curable resin composition is removed by wiping off, The coating method in the automobile painting line of Claim 1 characterized by the above-mentioned.   The painting method for an automobile painting line according to claim 1 or 2, wherein the other paints are an intermediate paint, a base paint, and a clear paint.   The ultraviolet curable resin composition contains 15 to 100 parts by weight of a reactive acrylate oligomer and 0.15 to 30 parts by weight of a polymerization initiator with respect to 100 parts by weight of an acrylic resin or a vinyl chloride resin. The painting method in the automobile painting line of any one of Claims 1 thru | or 3 characterized by these.

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