JPH0218478A - Production of coating for metal plate and coating metal plate - Google Patents

Abstract

PURPOSE:To obtain the title coating for electric equipment, etc., consisting essentially of thermally expansible micro-capsule, polyol, blocked polyisocyanate compound, etc. and capable of rapidly forming uniform foamed resin coating film on a metal plate and giving warm and soft feeling to appearance particular to metals. CONSTITUTION:The aimed coating consisting essentially of (A) 5-40wt.% thermally expansible micro-capsule, (B) polyol, (C) blocked polyisocyanate compound of 0.4-0.6 equivalent based on one equivalent hydroxyl group of the component B and (D) at least one kind of organic solvent selected from an aromatic hydrocarbon based solvent, alcohol based solvent, ether based solvent and ester based solvent. The coating is applied to metal surface and metal plate is heated to >=100 deg.C for 20-180sec to bake and cure the coating.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a novel paint for metal plates and a method for manufacturing coated metal plates using the paint.

More specifically, the present invention provides a foam finishing paint that can be applied to metal plates used for electrical equipment, indoor equipment, vehicle interiors, architectural interiors, etc. to provide an excellent appearance; The present invention relates to a method for producing a coated metal plate having a resin coating.

[Prior art] Unpainted metal materials have the appearance and feel unique to metal, giving the user a strong sense of security, but they have a hard, cold feel and lack of warmth, making them unsuitable for indoor decoration. It is unsuitable for this purpose.

Therefore, the problem is generally solved by improving the appearance by painting. Among such coatings, various decorative coating finishes, such as printed patterns, embossed finishes, and hammertone finishes, are used as a method to further reduce the appearance peculiar to metal. Furthermore, in order to improve the hard and cold feel of metal plates, a foam finish has been devised, and a water-based paint composition containing, for example, a foam resin has been proposed as a paint to be used (Japanese Unexamined Patent Publication No. 141072/1982).

On the other hand, regarding the coating method, conventionally users performed chemical conversion treatment and painting after molding, but in recent years metal plate manufacturers are switching to a continuous coating method, that is, a pre-coating method.

However, all of the conventional pre-coated metal plates have only improved the appearance, and have not yet overcome the disadvantages of the metal plate, such as hardness and coldness. As a means to eliminate such defects in the tactile surface of metal plates, it is possible to use, for example, a foamed resin coating.

As a paint for forming the foamed resin coating film, a water-based paint composition containing the above-mentioned foamed resin (Japanese Unexamined Patent Publication No. 141072/1982) is known, but this composition has a cationic interface which is a chain extender. It is a water-based dispersion type paint that contains an activator, and in order to volatilize the solvent water before the coating film hardens,
Requires a long pre-drying process.

However, since the pre-coated metal plate requires continuous coating and baking drying, a short baking process is essential.
If the baking treatment is carried out in a short period of time using the above-mentioned water-based paint, abnormal foaming is inevitable and a problem arises in that a homogeneous foamed coating film is not formed.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of conventional foamed resin-containing paints, forms a homogeneous foamed resin coating film on a metal plate in a short baking time, and provides a warm and To provide a paint for a metal plate that can provide a coated metal plate that is soft and has the appearance and feel of tanned leather or suede, and a method for producing a coated metal plate having the above-mentioned excellent characteristics using this paint. It was done for that purpose.

[Means for Solving the Problems] The present inventors have conducted intensive research to develop a paint for metal plates having the above-mentioned favorable properties and a method for manufacturing coated metal plates using the paint. The foamed resin paint, which consists of heat-expandable microcapsules containing low-boiling hydrocarbons, specific film-forming components, and specific organic solvents, can be baked at high temperatures for a short time, and is homogeneous and has a tanned leather. Based on this knowledge, it was possible to form a coating film that has a moist feel and a soft feel; it has elasticity and has a matte suede feel. As a result, the present invention was completed.

That is, the present invention provides (A) thermally expandable microcapsules, (B) polyols, (C) block type polyisocyanate compounds, and CD) aromatic hydrocarbon solvents, alcohol solvents, ether solvents, and ester solvents. A paint for a metal plate containing at least one organic solvent selected from among the main components, and after applying the paint to the metal surface to form a coating film, heat the metal plate for 20 to 180 seconds to bring the temperature of the metal plate to 1.
The present invention provides a method for producing a coated metal plate, characterized in that the coating film is cured by baking at a temperature of 00°C or higher.

The present invention will be explained in detail below.

In the paint of the present invention, thermally expandable microcapsules are used as component (A). This microcapsule is
The core material contains, for example, nitrogen, carbon dioxide, or a low boiling point hydrocarbon such as butane, and the wall film contains, for example, vinylidene chloride polymer,
High molecular polymers such as acrylonitrile polymers and melamine-formaldehyde resins are used. Further, the microcapsules may be obtained by any method, such as a coacervation method, an interfacial polymerization method, or an in-situ method. A specific example of this thermally expandable microcapsule is Matsumoto Microsphere F-3.
0 [manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd., trade name].

In the coating material of the present invention, the amount of the thermally expandable microcapsules is usually selected in the range of 5 to 40% by weight based on the solid content of the binder. If the amount is less than 5% by weight, the soft texture of the coating film will be poor, while if it exceeds 40% by weight, the texture of the coating film will tend to become rough, which is not preferable.

In the paint of the present invention, a combination of (B) polyol and (C) block type polyisocyanate compound is used as the binder component (coating film forming component). (B
There are no particular restrictions on the polyol of component (), and those conventionally used in urethane paints, such as polyester polyols, acrylic polyols, epoxy-modified polyols, etc., can be used. Specific examples of polyester polyols include Almatex P645, P646, P
Specific examples of acrylic polyols include 647BC1HMP15 [manufactured by Mitsui Toatsu Chemical Co., Ltd., trade name].
Acridic A-801, A-804, A-808 [
Dainippon Ink & Chemicals Co., Ltd., product name], Almatex 749-7.748-5M [Mitsui Toatsu Chemical Co., Ltd.
Specific examples of epoxy-modified polyols include Evicron H2O1-60BT and U16.
Examples include 0-60BT [manufactured by Dainippon Ink and Chemicals Co., Ltd., trade name]. These polyols are 1
A species may be used, or two or more species may be used in combination.

On the other hand, the blocked polyisocyanate compound used as component (C) is a polyisocyanate compound whose reactive incyanate groups are blocked with a blocking agent such as alcohols or phenols, and is inert at room temperature.
Examples of such substances include hexamethylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate,
Xylylene diisocyanate, dicyclohexylmethane diisocyanate, hydrogenated xylylene diisocyanate,
Polyisocyanate compounds such as naphthalene-1,5-diisocyanate and isopropylbenzene-2,4-diisocyanate whose incyanate groups are blocked with alcohols or phenols, or these polyisocyanate compounds with polyalkylene glycol or polyoxy Examples include prepolymers having terminal incyanate groups obtained by addition reaction with alkylene glycol, etc., in which the terminal isocyanate is blocked with alcohols or phenols.

A specific example of such a block type polyisocyanate compound is Oresta NP1060PB.

NPlooO, NP2O00 [manufactured by Mitsui Toatsu Chemical Co., Ltd.]
product name], etc. One type of these block type polyisocyanate compounds may be used, or two types may be used.
You may use combinations of more than one species.

The block type polyisocyanate compound of the component (C) has an isocyanate group of usually 0.4 to 1.6 equivalents, preferably 0.8 to 1.2 equivalents, per equivalent of the hydroxyl group of the polyol of the component CB). It is used in such a proportion that If this amount is less than 0.4 equivalent, the formed coating film may remain sticky and the desired coating properties may not be obtained.
．． If the amount exceeds 6 equivalents, the elasticity of the coating film will deteriorate, and the appearance of the foamed resin coating as a coating film will tend to be impaired, which is not preferable.

In the paint of the present invention, the binder component is the above-mentioned (B
A combination of component ) and component (C) is used, but if necessary, a melamine resin (amino resin) can be further blended. In this case, the ratio of melamine resin to polyol is preferably 1:99 to 30, based on weight.
: Selected from a range of 70. In the paint of the present invention, (D
The organic solvent used as component (A) must be one that does not attack the thermally expandable microcapsules of component (A), and is selected from aromatic hydrocarbon, alcohol, ether, and ester solvents; For example, if a ketone solvent is used, it is difficult to form a coating film with good foamability. Examples of the aromatic hydrocarbon solvent include benzene, toluene, xylene, methylnaphthalene, and cumene; examples of the alcohol solvent include methanol,
Ethanol, n-propertool, isopropertool, n
-butanol, isobutanol, 5ee-butanol,
t-Butanol, 2-methylbutanol, 3-methoxybutanol, isoamyl alcohol, methylamyl alcohol, 2-methylpentanol, diacetone alcohol, allyl alcohol, 2-ethylhexanol, cyclohexanol, benzyl alcohol, methylbenzyl alcohol, ethylene Glycol, propylene glycol, diethylene glycol, furfuryl alcohol, etc., and examples of ether solvents include isopropyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol heptanoethyl ether, propylene glycol monomethyl ether, diglopylene glycol. Examples of ester solvents include ethylene glycol acetate, ethylene glycol monoethyl ether acetate, ethyl acetate, n-propyl acetate, Isopropyl acetate, n-butyl acetate, isobutyl acetate, 5ec-butyl acetate, isoamyl acetate, benzyl acetate, cyclohexyl acetate, methyl propionate, 2,2,4-trimethyl-1,3-bentanediol monoisobutyrate, etc. It will be done.

These organic solvents may be used alone or
Two or more types may be used in combination as a mixed solvent, and
It is appropriately selected depending on the binder component used and the type of thermally expandable microcapsules.

Pigments such as inorganic pigments, organic pigments, and extender pigments can be blended into the paint of the present invention, if necessary. Examples of the inorganic pigments include white pigments such as titanium dioxide, zinc white, and white lead, black pigments such as carbon black, acetylene black, and graphite, red pigments such as vermilion, cadmium red, antimony vermilion, and red red, and navy blue. Examples include blue pigments such as , ultramarine, and cobalt blue; green pigments such as chromium oxide green, Guinea green, chrome green, zinc wire, and linear; and iron oxide pigments having various tones. Examples of organic pigments include azo-based, phthalocyanine-based, threne-based, quinacridone-based, dioxazine-based, and isoindolinone-based organic pigments, and extender pigments include, for example, chalk, precipitated calcium carbonate, dung, and pallite. Examples include powder, precipitated barium sulfate, clay, talc, silica powder, diatomaceous earth, alumina, and ceracola.

Furthermore, the coating composition of the present invention may optionally include additive components commonly used in conventional coating compositions, such as curing accelerators, antifoaming agents, thickeners, anti-settling agents, anti-sagging agents, anti-color separation agents,
Pigment dispersants, leveling agents, anti-skinning agents, anti-scratch agents, anti-mold agents, ultraviolet absorbers, antioxidants, antistatic agents, etc. can be added to the extent that they do not impair the purpose of the present invention. .

There are no particular restrictions on the method for preparing the paint of the present invention, and conventional methods can be used. That is, when no pigment is blended, the above (A), (B), (C), and C
It can be prepared by mixing each component of D) and any additional components used as desired and stirring thoroughly to homogeneously disperse the thermally expandable microcapsules of component (A). When blending, for example, (B
A part of the polyol of the component (D), a part of the organic solvent of the component (D), and a pigment are mixed to produce a roll mill, a cone mill, a flat stone mill, a speed dry mill, a ball mill, a sand grind mill, a pearl mill, an attriter, and a day silver. After grinding and dispersing the pigment to a desired particle size using
(C) Component block type polyisocyanate compound, (
Add the remainder of the organic solvent of component D) and any additional components used as desired, stir to mix, then add the thermally expandable microcapsules of component (A), stir thoroughly, and remove the pigment and micro-power. By homogeneously dispersing the cells, it can be prepared.

Next, a method for manufacturing a coated metal plate using the paint of the present invention prepared in this manner will be described. As the metal plate to be coated, for example, a cold rolled steel plate, various galvanized steel plates such as an electrolytic galvanized steel plate, a hot-dip galvanized steel plate, an aluminum plated steel plate, a stainless steel plate, an aluminum plate, etc. are used. These metal plates are usually degreased before being painted, and in some cases are further subjected to chemical rust removal treatment such as pickling or electrolytic pickling, and then treated with chemical conversion coatings such as chromate treatment or phosphate treatment. Processing is performed. The paint of the present invention can be applied directly onto the chemical conversion film formed in this way, but in order to improve performance such as corrosion resistance and adhesion, it is usually used on pre-coated metal plates. It is desirable to apply an epoxy resin undercoat, bake it, and then paint.

There are no particular restrictions on the coating method, and methods commonly used for conventional solvent-based coatings, such as brush coating, tampon coating, roll coater coating, spray coating, and air spray coating, can be used. The most common method for coating pre-coated steel sheets is a roll coater coating method. The coating film thickness is preferably in the range of 10 to 80 μm before baking hardening. If the film thickness is less than 10 μm, the softness of the coating film will be poor, while if it exceeds 80 pm, the texture of the coating film will become rough and the physical performance may deteriorate, which is not preferable. From the viewpoint of the appearance of the coating film, it is desirable that the film thickness before baking hardening is in the range of 20 to 40 μm.

Further, the viscosity of the paint at the time of application may be a commonly used viscosity, and in the case of roll coater application, 40 to 180 seconds at 7 ord cup #4 (25 DEG C.) is appropriate. Baking treatment involves heating the metal plate for 20 to 180 seconds to raise the temperature of the metal plate to 10
This is done by allowing the temperature to reach 0°C or higher. If the baking time is less than 20 seconds, the binder component may not be sufficiently cured, the formed coating film may be sticky, and the thermally expandable microcapsules may not be sufficiently foamed.
When the time exceeds 180 seconds, the microcapsules tend to disintegrate and the texture of the coating film tends to become rough. The temperature reached by the metal plate must be 100°C or higher in order to sufficiently foam the thermally expandable microcapsules and to harden the binder component. 40 to 1 in terms of paint film appearance, paint film physical properties, etc.
With a baking time of 00 seconds, the metal plate temperature is 120-220'C, preferably 160-210'C! It is desirable to reach this point. There is no particular restriction on the heating method, and any method can be selected and used, for example, from external heating methods such as convection heating method or radiation heating method, or internal heating method using high frequency or the like.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

The appearance and physical properties of the coating film were determined as follows.

(1) Appearance The appearance of the coating film was visually observed, and an appearance with soft elasticity was evaluated as @, and one without was evaluated as X.

(2) Pencil hardness It was determined in accordance with JIS K-5400.

(3) Make 100 cuts of 1a+mX1m#+ with an Eriksen cross cut cutter knife.
A sample was formed, extruded for 6 mrn using an Erichsen tester, and a cellophane tape peeling test was performed.

Adhesion was determined using a 10-point method.

(4) Salt water spray test JIS Z-23711: Judgment was made after spraying for 240 hours, and evaluation was made according to the following criteria.

■ = No abnormality observed Δ: Slight abnormality observed was dispersed with a disperser until the particle size was 15 μm or less, and then the remaining post-additives were added and stirred and dispersed, and the viscosity was adjusted to prepare a foamed resin coating.

Preparation of painted steel plate Plate thickness 0.2 which has been subjected to degreasing treatment and phosphate chemical treatment in advance
7111+l galvanized steel sheet was used. This was coated with an epoxy resin undercoat (commercially available paint Nippon Oil Co., Ltd., "Precolor Primer P32J") using a bar coater; then, it was baked in an atmosphere of 260° C. for 40 seconds to form a primer layer with a thickness of 5 μm.

Next, the above-mentioned foamed resin paint and comparative paint were coated with a bar coater to a wet film thickness of 30 μm, and then
A steel plate coated with a foamed resin paint and a steel plate coated with a comparative paint were obtained by baking the metal plate for a second to reach a temperature of 190°C.

Table 2 shows the appearance and physical properties of the coated steel sheet thus prepared.

Comparative Example 3 Preparation of Painted Steel Plate A primer layer was provided on a galvanized plate using an epoxy resin undercoat in the same manner as in Example 1, and then the composition shown in Table 1 was prepared in the same manner as in Example 1. A coated steel plate of Comparative Example 3 was obtained by applying the paint with a bar coater to a wet film thickness of 30 μm, and then baking the metal plate for 15 seconds to reach a temperature of 90°C.

Table 2 shows the appearance and physical properties of the coating film of this coated steel plate.

Comparative Example 4 Preparation of Painted Steel Plate A primer layer was provided on a galvanized plate using an epoxy resin undercoat in the same manner as in Example 1, and then the composition shown in Table 1 was prepared in the same manner as in Example 1. A coated steel plate of Comparative Example 4 was obtained by applying the paint with a bar coater to a wet film thickness of 30 μm, and then baking the metal plate for 200 seconds to reach a temperature of 230°C.

Table 2 shows the appearance and physical properties of the coated steel sheet thus prepared.

(Left below) As is clear from Table 2, Comparative Example 1 without thermally expandable microcapsules, Comparative Example 2 without block polyisocyanate, and Comparative Example 3 with insufficient baking time. In both cases, the appearance of the coating film in Comparative Example 4 was far inferior to that of the foamed resin steel sheet obtained in the example of the present invention. The appearance of each coating film in the Examples was warm, soft, and felt like tanned leather.

[Effects of the Invention] As explained above, according to the present invention, a coated metal plate having a uniform foamed resin coating can be rapidly manufactured.

The obtained painted metal sheet loses the hard, cold, and warm appearance and feel characteristic of metals, and has a warm, soft appearance and feel similar to tanned leather or suede, and is useful for electrical equipment, indoor equipment, It can be widely used for vehicle interiors, architectural interiors, etc. In addition, the paint of the present invention can be applied to a post-coat method in which the user paints it after molding, and in that case, it can be baked for a shorter time than conventional foamed resin paints, resulting in improved productivity, etc. It has the following advantages.

Claims (1)

[Scope of Claims] 1 (A) thermally expandable microcapsules, (B) polyol, (C) block type polyisocyanate compound, and (
D) A paint for metal plates whose main component is at least one organic solvent selected from aromatic hydrocarbon solvents, alcohol solvents, ether solvents, and ester solvents. 2. The coating according to claim 1 is applied to the surface of a metal plate to form a coating film, and then heated for 20 to 180 seconds to reach a temperature of 100°C or higher, and the coating film is cured by baking. A method for manufacturing a painted metal plate.