JP2001149852A - Coating film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a laminated coating film wherein, when a second coating film and a final coating film are formed on a first coating film formed from a porous material such as that of a PVC coating film containing a plasticizer by a wet-on-wet coating process, a boil or blister, or the like, due to a difference in the rate of a reaction at an interface between coated layers is controlled. SOLUTION: In the coating film forming method for forming a second coating film and a final coating film on a base material on which an electro-deposit and a PVC coating film are formed by a wet-on-wet process, the relationship between a reaction start time of the final coating T1t and a reaction start time of the second coating T1p is T1p>=T1t.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin plastisol coating film (hereinafter referred to as P
(Referred to as VC coating film) and a laminated coating film obtained by the method.

[0002]

2. Description of the Related Art A number of proposals have been made on so-called wet-on-wet painting, in order to respond to the need for two-tone painting, or so-called two-tone painting, and to contradict the need for labor saving. It has been done.

[0003] For example, in Japanese Patent Application Laid-Open No. 11-165123, in the two-tone coating finish, the intermediate coating 1 is the first coating.
, The first top coat base paint starts curing faster than the first top coat clear paint, and the middle coat paint 2 starts curing earlier than the first top coat clear paint. Two-tone paint finishing methods have been proposed.

[0004] On the other hand, as shown in FIG. 1, a lower surface of a car body, a side sill portion, a wheel house portion, or a floor back has conventionally been coated with a vinyl chloride resin on a coating film surface which has been subjected to chemical conversion treatment and electrodeposition coating. Plastisol paint (hereinafter, PVC)
The coating is obtained by heating and drying the coating, and the so-called chipping, which is caused by the collision of pebbles and gravel that the tire of the vehicle rolls up while the vehicle is running, causes the coating to peel off. I'm preventing.

[0005] Generally, a PVC coating is applied to the surface of an electrodeposited coating by airless spray coating or the like, and then pre-baked. Thereafter, an intermediate coating film was formed by the intermediate coating material, and after being cured, a top coating film was formed by the upper coating material.

[0006] The method according to the above publication is not sufficient for processes in which a PVC coating film is formed as a base, such as an automobile body. In particular, when the top coat forms a metallic coating formed by a metallic base coating and a clear coating, the reaction rates of the three different coatings are relatively controlled, for example, It is necessary to suppress problems such as swelling, swelling and the like.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to coat an intermediate coating film and a top coating film on an undercoat film formed of a porous material containing a plasticizer such as a PVC coating film by wet-on-wet. It is an object of the present invention to provide a method for forming a laminated coating film in which a bubble, a blister, and the like due to a difference in reaction rate at an interface between coating film layers are controlled.

Another object of the present invention is to provide a two-tone coating finish by wet-on-wet coating on an existing coating line, and to provide a two-tone coating formed by the method.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a method for forming an intermediate coating film and a top coating film on a base material on which an electrodeposition coating film and a PVC coating film are formed by wet-on-wet. The reaction start time T ₁ t of the top coat and the reaction start time T ₁ p of the intermediate coat are T ₁ p ≧ T ₁ t.
A coating film forming method characterized by the following relationship:

The present invention also relates to a method for forming a coating film, wherein the top coating film comprises a metallic base coating film and a clear coating film.
₁ b and the reaction start time T ₁ p of the intermediate coating film are T ₁
An object of the present invention is to provide a method for forming a coating film, wherein p ≧ T ₁ b.

In the present invention, further, in a two-tone coating finish in which the coating film surface is finished with a color 1 coating film and a color 2 coating film, an intermediate coating film 1 and a color 1 coating film are formed by the above-mentioned method and baked. Thereafter, the present invention provides a two-tone coating finishing method characterized by further forming a color 2 coating film.

Further, a two-tone coating finishing method is characterized in that after the intermediate coating film 1 is formed, the intermediate coating film 2 is formed at the color 2 coating film forming portion, and further the color 1 coating film is formed. Is provided.

Further, the present invention provides a laminated coating film formed by the above method. Hereinafter, the present invention will be described in more detail.

[0014] In the coating film formation method of a coating film forming method The present invention, after forming an electrocoating film, on uncured or cured electrodeposition coating film, to form a PVC coating film PVC coating, temporary baking or heat curing After that, an intermediate coating film and a top coating film are sequentially formed by wet-on-wet using the intermediate coating paint and the top coating paint, and the laminated coating film is finished.

Conventionally, it has been considered that the appearance of a laminated coating film formed by general wet-on-wet coating is established by curing the lower coating film in order.

However, as in the coating film forming method of the present invention, P
On the VC coating film, the reaction start time T ₁ t of the coating film formed by the top coat and the reaction start time T ₁ p of the intermediate coating film satisfy the relationship of T ₁ p ≧ T ₁ t. is important.
In addition, satisfying that T ₁ p−T ₁ t ≦ 2 minutes is satisfied.
It is more preferable from the viewpoint of improving the appearance and curability of the coating film.

That is, the fact that the reaction start time T ₁ t of the top coat as the upper layer is equal to or shorter than the reaction start time T ₁ p of the middle coat means that the reaction speed of the top coat is lower than that of the middle coat. Is equal to or greater than the reaction rate of By satisfying the above relationship, defects such as blisters and wrinkles caused by the PVC coating film as the undercoat layer can be contained.

In the coating film forming method of the present invention, the reaction start time T ₁ of each coating film is, as shown in FIG. The time when the coating film temperature reached the predetermined baking temperature was defined as zero (± 0), and the decrease start time determined from the plot of the vibration period measurement value was determined as the reaction start time. It is.

That is, the reaction start time T ₁ of the coating film in the coating film forming method of the present invention is, as shown in FIG.
In the vibration cycle-temperature graph, it is also the time from when the coating film reaches a predetermined baking temperature to when an inflection point at which the value of the vibration cycle sharply decreases due to the reaction of the paint appears.

More specifically, the measurement of the reaction start time T ₁ was performed using a rigid pendulum type physical property tester “DDV-OP” manufactured by Orientec.
AIII ", a dry film thickness on a metal support, an intermediate coating film of 30 μm, a metallic base coating film of 12 μm,
After applying each paint so that the clear coating film becomes 40 μm and setting in a room at a temperature of 25 ° C. and 60% RH for 3 minutes, the temperature of the coating film is raised to 30 ° C. and 30 ° C. after 1 minute.
10 minutes later, the temperature was raised to 140 ° C.
The test was carried out under the condition of keeping at 20 ° C. for 20 minutes. The reaction start time T ₁ was defined as a point at which the temperature of the coating film reached 140 ° C. ± 0.0 minutes.

On the other hand, when the top coat is a metallic coat formed by a metallic base coat and a clear coat, the reaction start time T ₁ b of the metallic base coat
And the reaction start time T ₁ p of the intermediate coating film, T ₁ p ≧ T ₁
It is important to satisfy the relationship of b. Further, more preferably _{T 1 p-T 1 b ≦} 2 minutes.

That is, it is necessary that the reaction start time T ₁ b of the metallic base coating film is equal to or smaller than the reaction start time T ₁ p of the intermediate coating film. The fact that the reaction start time is short indicates that the time required to start the reaction is short and the reaction is quick. The above conditions show that the reaction rate of the metallic base coating film is faster than that of the intermediate coating film.

Further, the reaction start time T ₁ c of the clear coating film
Relationship with is to satisfy the relationship of _{T 1 c> T 1 p ≧} T 1 b is, it is possible to preferably form an excellent multilayer coating film more appearance. That is, on the PVC coating film, it is preferable that the reaction rate of the metallic base coating film is the fastest, the next is the intermediate coating film, and the next is the clear coating film.

As one embodiment of the present invention, there is a method in which one part of a two-tone paint finish is applied by the coating film forming method of the present invention, and then a two-color top coat is formed. In the case of this two-tone coating, a PVC coating film is formed with a PVC coating material, and after pre-baking or heat curing, an intermediate coating film is applied to the color 1 coating film forming portion using the intermediate coating material used in the coating film forming method of the present invention. Then, an intermediate coating film 2 is formed at a position where a color 2 coating film is to be formed, while a partially overlapping portion is wet-on-wet coating. In addition, the intermediate coating film 2 can also be formed by an existing intermediate coating. Thereafter, a color 1 coating film is further formed on the intermediate coating film 1 by wet coating on the intermediate coating film 1 by wet-on-wet coating. Next, the laminated coating film finished by wet-on-wet is heat-cured to obtain an intermediate coating film and a color 1 coating film. Thereafter, a method of applying a top coat paint for forming the remaining color 2 coating film to the other top coat portions to complete two-tone coating is adopted.

In the case of the two-tone paint finish, PVC
The reactivity of the intermediate coating film and the top coating film finished by wet-on-wet coating on the coating film is the same as that of the above-mentioned coating film forming method, and the reaction start time of the top coating paint is changed to the reaction start time of the intermediate coating film. It must be the same or smaller than the time.

When the two-tone color 1 coating film is a metallic coating film, the intermediate coating film 1 and the intermediate coating film 2 are formed, setting is performed if necessary, and then the intermediate coating film 1 is formed. A metallic base coating film is formed on the metallic base coating film by wet-on-wet, and then a clear coating film is formed on the metallic base coating film by a clear coating by wet-on-wet and simultaneously baked and dried.

In addition to the metallic base coating and clear coating, a three-coat top coat of metallic base coating, mica base coating and clear coating can also be formed.

The intermediate coating film 2 and the top coating film 2 corresponding to the part where the color 2 coating film of the two-tone coating is to be formed are coated with a top coating material for forming the color 2 coating film after the intermediate coating film 2 is baked and cured. Since it is painted, it is not particularly limited, and an existing general intermediate paint or top coat may be used. The same paint system paint as the above-mentioned intermediate coat 1 or another paint, the top coat 2 is A functional paint such as an acid rain paint, an abrasion paint or a stain resistant paint may be used. Further, a highly decorative coating film, which is generally referred to as a mica coating film, can be formed by combining a metallic base paint with a mica base paint and a clear paint.

In the method for forming a coating film according to the present invention, by using a coating material which satisfies the conditions for the start time of the vibration cycle of each coating film due to FDOM, ie, the reaction starting time to be in the above order, the appearance of the coating film can be reduced. In addition, coating film defects such as wrinkles and reduced smoothness are less likely to occur, and a multicolor coating finish excellent in finished appearance can be obtained.

The film thickness of the laminated coating film formed in the present invention is usually 50 to 300 μm. Preferably 60-2
50 μm. If it exceeds the upper limit, the physical properties of the film such as a thermal cycle decrease, and if it falls below the lower limit, the strength of the film itself decreases.

After the application of the laminated coating film, the curing temperature for curing the coating film is 100 to 180 ° C., preferably 120 to 16 ° C.
A cured coating film having a high degree of crosslinking at 0 ° C. can be obtained. When the amount exceeds the upper limit, the coating film becomes hard and brittle, and when the amount is less than the lower limit, curing is not sufficient. The curing time varies depending on the curing temperature.
A temperature of 160 ° C. for 10 to 30 minutes is appropriate.

Intermediate coating film In the coating film forming method of the present invention, an intermediate coating material is used for forming the intermediate coating film.
Various inorganic pigments, extenders, thermosetting film-forming resins, curing agents and the like are included. However, the intermediate coating is not particularly limited, and may be any as long as it conceals base defects, ensures surface smoothness after top coating, and imparts coating properties such as impact resistance.

The above-mentioned intermediate coating composition may be prepared, for example, by adjusting the hydroxyl value or acid value of the curable film-forming resin, selecting a kind of a crosslinking agent such as an amino resin as a curing agent, and a kind of a curing catalyst to be combined with the crosslinking agent. The curing start time can be adjusted by selecting the amount, amount and the like.

The thickness of the intermediate coating film varies depending on the application, but in most cases, a thickness of 10 to 60 μm is useful. If it exceeds the upper limit, the sharpness may decrease, or problems such as unevenness or flow may occur at the time of painting.
The base cannot be concealed and the film breaks.

Examples of the color pigments contained in the intermediate coating composition include organic azo chelate pigments, insoluble azo pigments, condensed azo pigments, phthalocyanine pigments, indigo pigments, perinone pigments, perylene pigments, and dioxane. Pigments, quinacridone pigments, isoindolinone pigments, metal complex pigments, and the like. Inorganic pigments include graphite, yellow iron oxide, red iron oxide, carbon black, and titanium dioxide. As the extender, calcium carbonate, barium sulfate, clay, talc and the like are used.
Further, flat pigments such as aluminum powder and mica powder may be added.

As a standard, a gray intermediate paint containing carbon black and titanium dioxide as main pigments is used. Further, it is also possible to use a so-called color intermediate coating which is a combination of a set gray having a hue with the top coat and various kinds of coloring pigments.

The thermosetting film-forming resin used in the intermediate coating composition is not particularly limited, and may be a film-forming resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, or a urethane resin. Is available,
These are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. A combination of an alkyd resin and / or a polyester resin and an amino resin is preferred from the viewpoint of pigment dispersibility or workability.

Further, it is preferable to add a viscosity controlling agent to the above-mentioned intermediate coating material in order to prevent adaptation to the top coating film and to secure workability of coating. As the viscosity control agent, those having a thixotropic property can be generally used.

Examples of such a material include swelling dispersions of fatty acid amides, polyamides such as amide fatty acids and phosphates of long-chain polyaminoamides, and polyethylenes such as colloidal swelling dispersions of polyethylene oxide. , Organic acid smetite clay, organic bentonite type such as montmorillonite, aluminum silicate, inorganic pigments such as barium sulfate, flat pigments that exhibit viscosity depending on the shape of the pigment, non-crosslinking utilizing the interaction of polar groups or Crosslinkable resins or particles can be mentioned as viscosity control agents.

However, those which do not affect gloss when formed into a coating film are particularly preferred. Particularly preferred viscosity control agents include non-crosslinked or crosslinked resins or particles utilizing the interaction of polar groups. It can be used as a control agent.

Among the preferred crosslinkable resin particles,
Insoluble in organic solvents, average particle size is 0.02-0.5 μm
Is preferable. If the average particle size exceeds the upper limit, the stability will decrease. The above-mentioned crosslinkable resin particles include a resin having an emulsifying ability such as an alkyd resin or a polyester resin synthesized with a monomer having a zwitterionic group in the molecule as one of the polyhydric alcohol components, and the presence of a polymerization initiator. Below, what is obtained by carrying out emulsion polymerization of an ethylenically unsaturated monomer in an aqueous medium is preferable.

Examples of the monomer having a zwitterionic group in the molecule include -N ⁺ -R-COO ^- or -N ⁺ -RS.
O ₃ ^— (wherein R represents a C ₁ -C ₆ linear or branched alkylene group), and those having two or more hydroxyl groups can be used. As such a monomer, a hydroxyl group-containing aminosulfonic acid-type zwitterionic compound is preferable from the viewpoint of resin synthesis. Specific examples include bishydroxyethyl taurine.

The resin having an emulsifying zwitterionic group in the molecule, which is synthesized using the above monomer, has an acid value of 30 to 150 mgKOH / g, preferably 40 to 1 mgKOH / g.
50 mgKOH / g, number average molecular weight of 500 to 500
It is good to use 0, preferably 700-3000 polyester resin. If the upper limit is exceeded, the handleability of the resin will be reduced. If the lower limit is not reached, the resin having emulsifying ability will be desorbed when the coating film is formed, or the solvent resistance will be reduced.

In the synthesis of the crosslinkable resin particles, it is preferable to include a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule as the ethylenically unsaturated monomer to be emulsion-polymerized. Such a monomer having two or more radically polymerizable ethylenically unsaturated groups in the molecule is preferably contained in the range of 0.1 to 10% by weight of all the monomers. The amount is selected to provide sufficient crosslinking to dissolve the particulate polymer in the solvent.

The crosslinkable resin particles are generally contained in an emulsion resin, do not contain a low-molecular emulsifier or a protective colloid that lowers the performance when formed into a coating film, and are capable of polymerizing two or more radicals in a molecule. Since the polymer is crosslinked by copolymerizing a monomer having a suitable ethylenically unsaturated group, the coating film is excellent in water resistance, solvent resistance, gloss and the like.

The amount of the viscosity control agent is 0.01 to 15 parts by weight, preferably 0.1 to 13 parts by weight, more preferably 0.1 to 13 parts by weight, based on 100 parts by weight of the resin solid content of the intermediate coating composition. It is added in an amount of 2 to 12 parts by weight. If the amount of the viscosity control agent exceeds 15 parts by weight, the appearance is reduced and the viscosity control agent is added in an amount of 0.1%.
If the amount is less than 01 parts by weight, the effect of controlling the viscosity cannot be obtained, which may cause the layer to become familiar or inverted.

The method for producing the coating composition used in the present invention is not particularly limited, including those described below, and those skilled in the art such as kneading and dispersing a compound such as a pigment using a kneader or a roll. All known methods can be used.

The topcoat topcoat coating film, a solid coating generally does not contain the bright pigment can be classified in the metallic coating containing bright pigment, the topcoat in the coating film forming method of the present invention ,
It may be a solid coating formed by a solid paint, or a metallic coating formed by a metallic base coating and a clear coating. Each of these paints for forming the overcoating film contains a film-forming thermosetting resin, a curing agent, and, if necessary, a coloring pigment, a glittering pigment, and the like.

The above-mentioned top coating composition is prepared by, for example, adjusting the hydroxyl value or acid value of the thermosetting resin for forming a coating film, selecting a crosslinking agent such as an amino resin as a curing agent, and a curing catalyst used in combination with the crosslinking agent. The curing start time can be adjusted by selecting the type, amount, etc.

The thickness of the above-mentioned top coat varies depending on the desired use, but in most cases, a thickness of 10 to 60 μm is useful.
If the upper limit is exceeded, the sharpness may deteriorate, or problems such as unevenness or flow may occur at the time of coating. If the lower limit is not reached, the base material cannot be concealed and the film is cut.

The film-forming thermosetting resin contained in the top coating composition is not particularly limited, and may be a film-forming resin such as an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin, or a urethane resin. They can be used and are used in combination with a curing agent such as an amino resin and / or a blocked isocyanate resin. From the viewpoint of pigment dispersibility or workability, a combination of an acrylic resin and / or a polyester resin with a melamine resin is preferred.

As the above-mentioned coloring pigment, for example, those mentioned in the description of the above-mentioned intermediate coating material can be used. Furthermore, it is preferable to add a viscosity control agent to the top coat, like the above-mentioned intermediate coat, in order to ensure coating workability. The viscosity controlling agent is used for favorably forming a coating film without unevenness and sagging, and generally, those exhibiting thixotropic properties can be used. As such a material, for example, those described in the description of the intermediate coating material can be used.

The total solid content of the top coat used in the present invention is 15 to 70% by weight, preferably 18 to 50%.
% By weight. Exceeding the upper and lower limits lowers the paint stability. If the upper limit is exceeded, the viscosity is too high and the appearance of the coating film is reduced, and if it is lower than the lower limit, the viscosity is too low and poor appearance such as adaptability and unevenness occurs.

In general, a solution type paint is preferably used as the top coat used in the present invention. If the solution type is a solution type, an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion) or a non-aqueous type can be used. Either may be used.

Metallic Coating In the case where the above top coat is a metallic coating formed by a metallic base coating and a clear coating, the metallic base coating used for forming the metallic base coating is as described above. In addition to the resin component described in the top coat, a glitter pigment is further contained.

As in the case of the above top coat, for example, adjustment of the hydroxyl value or acid value of the film-forming thermosetting resin, selection of a kind of a crosslinking agent such as an amino resin as a curing agent, and curing in combination with a crosslinking agent. The curing start time can be adjusted by selecting the type and amount of the catalyst.

The brilliant pigment contained in the metallic base paint is not particularly limited in its shape, and may be further colored. For example, the brilliant pigment having an average particle size (D ₅₀ ) of 2 to 5 may be used.
It is preferable that the thickness is 0 μm and the thickness is 0.1 to 5 μm. Those having an average particle size in the range of 10 to 35 μm are excellent in glitter and are more preferably used.

The pigment concentration (PW) of the bright pigment in the paint
C) is generally at most 20.0%. If it exceeds the upper limit, the appearance of the coating film will be reduced. Preferably, 0.01% to 1%
8.0%, and more preferably 0.01% to 16%.
0%.

The glitter pigments include aluminum,
Non-colored or colored metal glitters such as metals or alloys such as copper, zinc, iron, nickel, tin and aluminum oxide, and mixtures thereof. Further, interference mica pigments, white mica pigments, graphite pigments, and other colored or colored flat pigments may be used in combination.

The total pigment concentration (PWC) in the paint, including the glitter pigments and all other pigments, is set to 0.1.
1% to 50%, preferably 0.5% to 40%, more preferably 1.0% to 30%. If it exceeds the upper limit, the appearance of the coating film will be reduced.

When the above metallic base paint is used as an aqueous paint, US Pat.
Thermosetting film-forming resins specifically described in, for example, JP-A-151125 and JP-A-5183504 can be used. Particularly, a thermosetting film-forming resin obtained by combining an acrylic resin having an acrylamide group, a hydroxyl group and an acid group described in U.S. Pat. No. 5,183,504 with a melamine resin is excellent in finish and appearance.

Clear Coating When the top coat is a metallic coating, the clear coating forming the clear coating is not particularly limited, and a clear coating containing a film-forming thermosetting resin and a curing agent. Can be used.

In the same manner as in the above-mentioned top coating, for example, the above-mentioned clear coating is used to adjust the hydroxyl value or acid value of the thermosetting resin for forming a coating film, to select the kind of a cross-linking agent such as an amino resin as a hardening agent, and to perform cross-linking. The curing start time can be adjusted by selecting the type and amount of the curing catalyst to be combined with the agent.

The thickness of the clear coating film varies depending on the desired use, but in most cases, 10 to 60 μm is useful. If it exceeds the upper limit, sharpness may deteriorate, or problems such as unevenness, pinholes or flow may occur at the time of coating. If it is less than the lower limit, the substrate cannot be concealed and the film may be cut.

The film-forming thermosetting resin contained in the clear coating is not particularly limited, and for example, those mentioned in the description of the intermediate coating can be used. Further, in the clear paint,
Like the above-mentioned intermediate coating, it is preferable to add a viscosity control agent in order to secure the coating workability. The viscosity controlling agent is used for favorably forming a coating film without unevenness and sagging, and generally, those exhibiting thixotropic properties can be used. As such a material, for example, those described in the description of the intermediate coating material can be used.

The clear paint is applied in an uncured state after the mica base paint having an interference color is applied.
To prevent break-in, inversion, or sagging between layers,
It is preferable to contain the viscosity control agent described above. The added amount of the viscosity controlling agent is 10% of the resin solid content of the clear coating composition.
0 to 10 parts by weight, preferably 0.02 to 8 parts by weight, more preferably 0.03 to 6 parts by weight with respect to 0 parts by weight.
It is added in parts by weight. When the amount of the viscosity controlling agent exceeds 10 parts by weight, the appearance is deteriorated, and when the amount is less than 0.1 part by weight, the effect of controlling the viscosity cannot be obtained, which causes problems such as sagging.

The solid content in the clear paint is from 20 to
It is 60% by weight, preferably 35 to 55% by weight. The solid content at the time of application is 10 to 50% by weight, preferably 20 to 50% by weight.

The coating form of the clear coating used in the present invention may be any of an organic solvent type, an aqueous type (water-soluble, water-dispersible, emulsion), a non-aqueous-dispersion type and a powder type. A catalyst, a surface preparation agent and the like can be used.

Substrates The coating film forming method of the present invention can be advantageously used for various substrates, for example, metals, plastics, foams and the like, particularly metal surfaces and castings. Can be particularly preferably used.

The metal products include, for example, iron, copper,
Aluminum, tin, zinc, and the like, and alloys containing these metals are included. Specific examples include automobile bodies and parts such as passenger cars, trucks, motorcycles, and buses. It is particularly preferable that these metals have been previously subjected to a chemical conversion treatment with a phosphate, a chromate or the like.

PVC Coating PVC Used in the Method for Forming a Metallic Coating of the Present Invention
A PVC coating material for forming a coating film contains a vinyl chloride-based polymer or copolymer resin, a plasticizer, a filler, an adhesion-imparting agent, and the like as main components.

As the vinyl chloride resin contained in the PVC coating, a resin appropriately selected from homopolymers such as vinyl chloride monopolymer and vinylidene chloride monopolymer and copolymers with vinyl acetate is used. it can.

A plasticizer is required to make these resins into a paint. DOP, DEP, DB
Phthalate plasticizers such as P, DMP, and GIMP;
It is appropriately selected from phosphate ester plasticizers such as TEP and TCP, other aliphatic monobasic acid esters, aliphatic dibasic acid esters, and dihydric alcohol esters, and used.

Examples of the filler include powdery fillers such as calcium carbonate, barium sulfate, calcium oxide, clay and talc, flake-like fillers such as mica and graphite, acicular calcium metasilicate, zonolite and potassium titanate. , Rock wool staple fiber, glass fiber staple fiber, aluminum silicate, carbon fiber staple fiber, aramid fiber staple fiber, etc. needle-like filler, glass balloon, silica balloon, carbon inorganic hollow sphere etc., inorganic hollow filler, vinylidene chloride An organic hollow filler such as a plastic balloon made of an organic synthetic resin such as acrylonitrile, a coloring agent, and the like can be used.

In addition to the above components, one or more active hydrogen-containing components selected from polyamines, polyamides, polyols and the like as an adhesion-imparting agent, and a polyisocyanate having a terminal NCO group blocked by a suitable blocking agent And mixtures with prepolymers. Polyisocyanate prepolymers are aromatic or aliphatic diisocyanates, for example, hexamethylene diisocyanate, diphenylmethane diisocyanate, octane methylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, phenyl diisocyanate, tetramethylene diisocyanate, methyl xylylene diisocyanate, etc. One or more selected ones can be used, and tolylene diisocyanate is particularly preferably used.

As a blocking agent for blocking the NCO group, phenol, acid amide, lactam, lower monohydric alcohol, cellosolve, caprolactam, oximes and the like can be used, and methyl ethyl ketoxime is particularly preferably used. It is appropriate that the blocking agent starts dissociating at a temperature of about 100 ° C. or more,
The O group is regenerated and undergoes an addition reaction with an active hydrogen-containing component such as polyamide, polyamine or polyol. In this way, strong adhesion can be imparted to the vinyl chloride plastisol paint.

If necessary, a polyfunctional monomer having one or more double bonds, such as diallyl phthalate, ethylenediamine methacrylate, triallyl isocyanurate, trimethylolpropane trimethacrylate, can be compounded as a crosslinking assistant. . These can increase the elasticity of the vinyl chloride plastisol coating film by improving the crosslinking efficiency of the crosslinking reaction of the vinyl chloride resin, and can improve the chipping property. Organic peroxides can also be blended because they can achieve substantially the same role and effect as the crosslinking assistant. Peroxyketal, which is relatively stable, of radicals generated by thermal decomposition,
Dialkyl peroxides can be used. In addition, a foaming agent can be included. As such, dinitrosopentamethylenetetramine, azodicarbonamide,
4,4 ′ oxybisbenzenesulfonyl hydrazide,
Examples thereof include p-toluenesulfonyl hydrazide, p-toluenesulfonylacetone hydrazone, and hydrazodicarbonamide. These generate gas by heating of coating film drying, fill the inside of the coating film with the gas,
This is for improving the chipping property by increasing the thickness of the coating film.

Electrodeposition Coating As the electrodeposition coating which is applied on the chemical conversion-treated steel sheet and forms an undercoat layer used in the method for forming a metallic coating film of the present invention, cationic and anionic types can be used. The electrodeposition coating composition is preferable because it gives a laminated coating film having excellent corrosion resistance.

[0079]

EXAMPLES The present invention will be described in detail with reference to specific examples, but the present invention is not limited to the following examples. In the following, “parts” means “parts by weight”.

Preparation Example Preparation of Crosslinkable Resin Particles In a reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube, a cooling tube and a decanter, 213 parts of bishydroxyethyl taurine, 208 parts of neopentyl glycol, 296 parts of phthalic anhydride , 376 parts of azelaic acid and 30 parts of xylene were charged and heated. Water generated by the reaction was removed by azeotropic distillation with xylene. The temperature of the reaction solution was set to 210 ° C. over about 3 hours from the start of reflux, and stirring and dehydration were continued until the acid value equivalent to carboxylic acid reached 135 mgKOH / g (solid content).

After cooling the liquid temperature to 140 ° C., 500 parts of Kjular E10 (trade name; versidic acid glycidyl ester manufactured by Shell Co.) was added dropwise over 30 minutes, and then the reaction was continued for about 2 hours while stirring. finished. Acid value 55 mgKOH / g of solid content, hydroxyl value 91 mgKOH / g
g and a zwitterionic group-containing polyester resin having a number average molecular weight of 1250 were obtained.

This amphoteric ion-containing polyester resin 10
Parts, 140 parts of deionized water, dimethylethanolamine 1
Parts, 50 parts of styrene and 50 parts of ethylene glycol dimethacrylate were vigorously stirred in a stainless steel beaker to prepare a monomer suspension. Also, an aqueous initiator solution was prepared by mixing 0.5 parts of azobiscyanovaleric acid, 40 parts of deionized water and 0.32 parts of dimethylethanolamine.

A reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen inlet tube and a cooling tube was charged with 5 parts of the amphoteric group-containing polyester resin, 280 parts of deionized water, and 0.5 part of dimethylethanolamine. The temperature rose.
Here, 251 parts of the monomer suspension and 40.
82 parts were simultaneously added dropwise over 60 minutes, and the reaction was further continued for 60 minutes, and then the reaction was terminated.

A crosslinkable resin particle emulsion having a particle diameter of 55 nm as measured by the dynamic light scattering method was obtained. Xylene was added to this crosslinkable resin particle emulsion, water was removed by azeotropic distillation under reduced pressure, and the medium was replaced with xylene to obtain a xylene solution of crosslinkable resin particles having a solid content of 20% by weight.

Preparation of Intermediate Paint 1 The intermediate paint 1 for forming the intermediate coat 1 was prepared with the following composition (PWC = 36%). The reaction start time was measured using a rigid pendulum type physical property tester “DDV-OPAIII” manufactured by Orientec Co., Ltd. so that the dry film thickness of the intermediate coating film on the metal support was 30 μm. After setting for 3 minutes in a room at a temperature of 25 ° C. and 60% RH, the temperature of the hot plate was raised to 30 ° C.
After 10 minutes from 0 ° C., the temperature was raised to 140 ° C. and 1
The test was performed under the condition of holding at 40 ° C. for 20 minutes. Intermediate coating 1
The reaction start time T ₁ p at 140 ° C. baking was 0.3
Minutes. 13.20 parts of Taipaque R-820 (titanium oxide pigment manufactured by Ishihara Sangyo Co., Ltd.) 0.05 parts of Mitsubishi Carbon MA-100 (black pigment manufactured by Mitsubishi Chemical Corporation) 6.30 parts of Variace B-30 (barium sulfate pigment manufactured by Sakai Chemical Co., Ltd.) ) Thermosetting acrylic resin A 16.90 parts (Nippon Paint Co., Ltd., hydroxyl value 63, acid value 15, number average molecular weight 1630, solid content 65%) Thermosetting acrylic resin B 17.70 parts (Nippon Paint Co., Ltd.) , Hydroxyl value 92, acid value 8, number average molecular weight 1840, solid content 70%) 13.75 parts of imino group type methyl / butyl mixed etherified melamine resin (solid content 80%, polymerization degree α = 2.1) acrylic 0.30 parts CAB-381-0.5 2.00 parts (cellulose viscosity control agent manufactured by Eastman Chemical Co.) Crosslinked resin particles (solid content 20) %) 2.50 parts n-butanol 4.50 parts xylol 2.60 parts ethylethoxypropionate 10.20 parts butyl acetate 10.00 parts total 100.00 parts

Preparation of Intermediate Paint 2 An intermediate paint 2 for forming the intermediate coat 2 was prepared with the following composition (PWC = 42%). When the reaction start time was measured in the same manner as for the intermediate coat 1, the reaction start time T ₁ p of the intermediate coat 2 after baking at 140 ° C. was 3.9 minutes. Taipaek R-820 17.70 parts (Titanium oxide pigment manufactured by Ishihara Sangyo) Mitsubishi Carbon 100 0.02 parts (Black pigment manufactured by Mitsubishi Chemical) Variace B-30 10.40 parts (Barium sulfate pigment manufactured by Sakai Chemical) Heat 19.20 parts of curable acrylic resin B (manufactured by Nippon Paint Co., Ltd., hydroxyl value 92, acid value 8, number average molecular weight 1840, solid content 70%) 13.30 parts of thermosetting acrylic resin C (manufactured by Nippon Paint Co., Ltd.) Hydroxyl value 30, acid value 5, number average molecular weight 4100, solid content 50%) methylol group type methylated melamine resin 15.30 parts (solid content 90%, polymerization degree α = 2.6) butyl etherified melamine resin 7. 70 parts (solid content 60%) Acrylic surface conditioner 0.20 part n-butanol 4.50 parts xylol 5.90 parts butyl acetate 5.78 parts Total 100.00 parts

Example 1 Formation of Laminated Coating Film After zinc phosphate treatment, a cationic electrodeposition coating material “Power Top U-50” (manufactured by Nippon Paint Co., Ltd.) was dried at a dry film thickness of 20%.
In a side sill portion of an automobile body, which is electrodeposited to a thickness of μm and baked at 160 ° C. for 30 minutes, contains a PVC paint (30% by weight of a vinyl chloride resin, GIMP, calcium carbonate, an adhesion promoter, a solvent, etc.). (PVC resin plastisol paint, solid content: about 70%) was airless spray-coated to form a PVC coating film on the side sill portion. Next, temporary baking was performed at 120 ° C. for 10 minutes.
Next, the gray intermediate coating material 1 prepared in advance was spray-coated to form an intermediate coating film 1. In addition, intermediate coating film 1
The reaction start time T ₁ p was 0.3 minutes.

Next, a metallic base paint “OTO-H” was applied on the obtained intermediate coating film 1 by wet-on-wet.
330 champagne silver mica ”(Nippon Paint Co., Ltd., acrylic / melamine resin paint) with a dry film thickness of 1
Spray coating was performed to a thickness of 5 μm. The reaction starting time T ₁ b of the metallic base coating film was -0.5 min. After an interval of 4 minutes, a clear paint “OTO-567 Clear” (acrylic melamine resin paint, manufactured by Nippon Paint Co., Ltd.) was further spray-coated on a wet-on-wet basis so that the dry film thickness became 30 μm. . The reaction start time T ₁ c of the clear coating film
Was 2.9 minutes. After 7 minutes setting, 1
Baking was performed at 40 ° C. for 20 minutes to form a laminated coating film. The laminated coating film obtained on the side sill was free from defects such as blisters and wrinkles, and an automobile body having an excellent appearance was obtained.

Example 2 Formation of Two- Tone Coating Film A cationic electrodeposition coating material “Power Top U-50” (manufactured by Nippon Paint Co., Ltd.) was applied to a zinc phosphate-treated automobile door member.
Is electrodeposited to a dry film thickness of 20 μm.
Bake at 0 ° C. for 30 minutes. Next, a PVC paint (30% by weight of vinyl chloride resin, GIM
Vinyl chloride resin plastisol paint containing P, calcium carbonate, adhesion promoter, solvent, etc., solid content about 70%)
Was subjected to airless spray coating to form a PVC coating film such that a boundary was formed at about a half portion from the lower part of the door member. Next, temporary baking was performed at 120 ° C. for 10 minutes.

Next, as shown in FIG. 2, the pre-adjusted gray intermediate coating material 1 is applied so that the dry film thickness is 25 μm, and about 1/2 of the boundary from the lower part of the door member is a boundary. To form an intermediate coating film 1 on the lower half of the door member. After setting for 2 minutes, the preliminarily prepared intermediate coating material 2 was spray-coated so that about 1/2 of the upper part of the door member became a boundary, and the intermediate coating film 2 was formed on the upper half of the door.

Next, as shown in FIG. 2, a metallic base paint “OTO-H330 champagne silver mica” was applied on the obtained intermediate coating film 1 by wet-on-wet.
(Nippon Paint Co., Ltd. acrylic / melamine resin paint)
Was spray-coated so that the dry film thickness became 15 μm. After an interval of 4 minutes, clear paint "OTO-567 clear" is applied on a wet-on-wet basis.
(Nippon Paint Co., Ltd. acrylic / melamine resin paint)
Was spray-coated so that the dry film thickness was 30 μm. After setting for 7 minutes, it was baked at 140 ° C. for 20 minutes to form a cured color 1 coating film.

Next, a masking tape is applied to the boundary so that the paint for forming the color 2 coating does not scatter on the color 1 coating, and the intermediate coating 2 is covered from the boundary of the color 1 coating. ,
Gray metallic base paint “OT” on the upper half of the door member
O-H400 20D Metallic "(Nippon Paint Co., Ltd., acrylic / melamine resin paint) having a dry film thickness of 1
Spray coating was performed to a thickness of 5 μm. After an interval of 4 minutes, the clear paint “MAC-O 600 Clear” (Nippon Paint Co., Ltd., acrylic melamine resin paint) was further wet-on-wet to a dry film thickness of 3
It was spray-coated so as to have a thickness of 0 μm. After setting for 7 minutes, it was baked at 140 ° C. for 20 minutes to form a color 2 coating film.

The resulting two-tone laminated coating film was free from defects such as blisters and wrinkles, and an automobile door member having an excellent appearance was obtained.

From the above results, it can be seen that the laminated coating films of Examples 1 and 2 according to the present invention have excellent laminated coating films free from defects such as blisters and wrinkles despite being formed on PVC coating films. I got it.

[0095]

According to the method of the present invention, the intermediate coating film and the metallic base coating film can be controlled by controlling the reaction start time of the laminated coating film even though the base material is the PVC coating film which is a porous material. In addition, three layers of different materials, namely, a clear coating film and a clear coating film, could be coated by wet-on-wet, and a laminated coating film could be formed without causing problems such as blisters and wrinkles.

Further, by forming a laminated coating film on a wet-on-wet basis, the need for forming a multicolored coating film and the economics of a coating line can be achieved. A two-ton coating formed could be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an automobile body part on which a PVC coating film is formed.

FIG. 2 is a cross-sectional view showing the structure of a two-tone coating film formed on a door member of an automobile by the coating film forming method of the present invention.

FIG. 3 is a graph showing a vibration cycle curve and a temperature rising curve in a free damping vibration type viscoelasticity measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Automobile door member 2 ... PVC coating 3 ... Side sill portion of automobile body 4 ... Intermediate coating 2 5 ... Top coating 2 6 ... Intercoat 1 7: Metallic base coating 8: Clear coating

Claims (5)

[Claims] In a method of forming an intermediate coating film and a top coating film on a substrate on which an electrodeposition coating film and a PVC coating film are formed by wet-on-wet, the reaction of the top coating film is started. A coating film forming method, wherein a time T ₁ t and a reaction start time T ₁ p of the intermediate coating film are in a relationship of T ₁ p ≧ T ₁ t. 2. A method for forming a coating film, wherein the top coat film comprises a metallic base coat film and a clear coat film, wherein a reaction start time T ₁ b of the metallic base coat film and a reaction of the intermediate coat film 2. The coating film forming method according to claim 1, wherein the start time T ₁ p is in a relationship of T ₁ p ≧ T ₁ b. 3. A two-tone paint finish in which the paint film surface is finished with a color 1 paint film and a color 2 paint film.
3. A two-tone coating finishing method, wherein a coating film is formed by the method according to claim 1 or 2, and after baking, a two-color coating film is further formed. 4. The method according to claim 1, wherein after the intermediate coating film 1 is formed, an intermediate coating film 2 is formed at a color 2 coating film forming portion, and further a color 1 coating film is formed. 3. The two-tone paint finishing method according to any one of 3. 5. A laminated coating film formed by the method according to claim 1.