JPH0411672A - Coating material for metallic plate, metallic plate coated therewith, and manufacture of coated metallic plate - Google Patents

Abstract

PURPOSE:To obtain the title coating material which can form a coating film excellent in marring resistance, abrasion resistance, etc., with a soft matte appearance by incorporating acrylic polymer beads containing a specified amount of a crosslinking agent into a coating material composed mainly of a polyvinylidene fluoride and an acrylic resin. CONSTITUTION:A coating material composed mainly of a polyvinylidene fluoride and an acrylic resin is mixed with 0.1-30wt.%, based on the coating solids, acrylic polymer beads containing 2-20wt.% crosslinking agent and, if necessary, an inorganic aggregate (e.g. glass beads), an organic aggregate (e.g. nylon beads), a pigment, a solvent, etc., to produce a coating material for metallic plates. By applying this coating material to a metallic plate and heating the plate to 100 deg.C or above for baking and curing, a coated metallic plate suitable for electrical machinery, vehicle interior, etc., can be obtained.

Description

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

More specifically, a finishing paint that is applied to a metal plate used for electrical equipment, indoor equipment, vehicle interiors, building interiors and exteriors, etc. to give it a unique appearance, and a painted metal plate produced using the paint; and its manufacturing method.

[Conventional technology]

Painted metal sheets that are widely used in parts that require long-term durability such as roofs and building exteriors, electrical equipment, indoor equipment, vehicle interiors, and building interiors are generally called prepainted steel sheets.

Commonly used materials for painted metal plates include hot-dip galvanized steel plates, zinc/aluminum alloy plated steel plates, aluminum plated steel plates, stainless steel plates, and aluminum plates.

In recent years, market demands have become increasingly strict for painted metal temporary used for roofs, building exteriors, etc., and long-term durability and long-term warranties are now required. Fluororesin paints containing 70% by weight or more of polyvinylidene fluoride are becoming mainstream as paints for this purpose, and the quality standards for these paints are as follows: (1) Accelerated weather resistance test: Discoloration after 1,500 hours of NBS color difference ( △E) is 7 or less, ■ Salt water spray test 2.0
Currently, they must have a performance of ASTM 8F or higher at 00 hours, and are required to have a long-term warranty.

[Problem to be solved by the invention]

However, current fluororesin paints still have potential problems such as pressure marks during coiling and scratches during molding and construction.

In JP-A No. 61-236869, inorganic aggregate (glass fiber, etc.) is blended into the above-mentioned fluororesin paint to improve the strength and hardness of the paint film, and improve processability such as scratch resistance and abrasion resistance. Paints with excellent water permeability and other properties have been disclosed. However, since this paint uses hard aggregate,
There is a risk of new problems such as abrasion of the forming roll and abrasion of the shearing blade during the forming process.

The purpose of the present invention is to almost eliminate pressure marks during winding, scratches on the painted surface during forming and construction, and wear of forming rolls and shearing blades, while at the same time providing an excellent new warm and soft design. The present invention provides a paint for metal plates that has a good finish, as well as the formability and long-term durability of conventional coated metal plates, a coated metal plate coated with the paint, and a method for manufacturing such coated metal plates. It is on offer.

[Means to solve the problem]

As a result of intensive research to achieve the above object, the present inventors have found that a finish with a unique design can be obtained without compromising good moldability or durability in the slightest. They discovered this and completed the present invention.

That is, the present invention provides a paint whose main component is a resin component consisting of polyvinylidene fluoride and an acrylic resin, in which the solid content of the paint contains 0.0% of acrylic polymer beads containing 2 to 20% by weight of a crosslinking agent. The object of the present invention is to obtain a paint for a metal plate characterized in that the content is 1 to 30% by weight.

Another object of the present invention is to obtain a coated metal plate having a top coat formed on the plate surface by applying the above-mentioned paint.

Further, the present invention provides a method for producing a coated metal plate, which comprises applying the above-mentioned coating material to a metal plate and then heating the metal plate to reach a temperature of 100° C. or more, and baking and curing the coating.

As polyvinylidene fluoride, the weight average molecular weight is 400.
,000 or more and a melting point of 150-180°C. For example, Kynar 500 (trade name of Nippon Pennwalt ■, weight average molecular weight 650゜000, melting point 160~1
65℃).

As the acrylic resin, 70% by weight or more of the polymerized units are (meth)acrylic acid alkyl ester monomers having 1 to 10 carbon atoms, such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate. , propyl (meth)acrylate, amyl (meth)acrylate,
It is composed of one or more of hexyl (meth)acrylate and octyl (meth)acrylate, and has a weight average molecular weight of 50,000 to 200,000. More preferably, 50% by weight or more of the polymerized units constituting the acrylic resin are methyl methacrylate.

Similarly, as the polymer constituting 30% by weight or less of the polymerized units of the acrylic resin, any material that can be copolymerized with the above-mentioned acrylic resin may be used. Examples of such monomers include (meth)acrylic acid, styrene, vinyltoluene, (meth)acrylonitrile, (meth)acrylamide, and vinyl chloride. The mixing ratio of the above polyvinylidene fluoride and acrylic resin is 90:10 to 40.
:60 weight ratio is preferred.

In the present invention, the acrylic polymer beads mixed into the conventional paint must have a quality that does not impair the excellent properties of the conventional paint and its coating film. Specifically, it is required that it hardly dissolves in the solvents in conventional paints, that it does not reduce the storage stability of paints, and that it has compatibility with acrylic resins in paints.

Therefore, the monomer composition and crosslinking density of the acrylic polymer forming the beads include 80 to 98% by weight of MMA (methyl methacrylate), 18% by weight or less of monomers copolymerizable with MMA, and a crosslinking agent (ethylene glycol dimethacrylate). ) is preferably 2 to 20% by weight, preferably 5 to 10% by weight.

If the crosslinking agent exceeds 20% by weight, the beads will be too hard.
This is undesirable since there is a risk of scratches on the back surface or other problems when winding up the metal plate.

The particle size of acrylic polymer beads is 10 to 50 μm.
φ, preferably 20 to 40 μmφ.

If the diameter is less than 10 μm, the unique design which is the object of the present invention cannot be obtained, and if it exceeds 50 μm, the sedimentation of the beads in the paint becomes significant, and both are not preferred.

Acrylic polymer beads may be mixed into the paint as is, but in order to improve their affinity and dispersibility in the paint and reduce the risk of sedimentation, the beads may be surface-treated with a coupling agent. It can also be mixed into paints later.

As a specific surface treatment method, an aluminum-based coupling agent, such as Plenac) ALM (trade name of Ajinomoto, chemical name: acetalkoxyaluminum diisopropylate, -max (I))] (R: c + ~ C8 alkyl After dissolving 3% by weight of acrylic polymer beads in isophorone, Heavy's was added therein to bring them into good contact.

The proportion of acrylic polymer beads mixed into the paint is 0.1 to 30% by weight, preferably 5 to 20% by weight. If it is less than 0.1% by weight, the unique design which is the object of the present invention will be impaired, and if it exceeds 30% by weight, the properties of the paint will deteriorate, the workability of the paint will be affected, and the finish of the painted surface will deteriorate, resulting in unsatisfactory results. be.

A conventional method for incorporating acrylic polymer beads into a paint is to add the acrylic polymer beads to the paint while gently stirring the paint and mix uniformly.

In the paint for metal plates of the present invention, inorganic or organic aggregates, coloring pigments, extender pigments, solvents, additives, and the like can be blended as necessary in addition to the above-mentioned essential components.

Examples of the inorganic aggregate include glass beads, glass fibers, alumina fibers, alumina particles, silica, and calcined silica.

Examples of organic aggregates include polyacrylonitrile beads, benzoguanamine beads, and nylon beads.

Examples of color pigments include titanium oxide, carbon blank, iron oxide, lead chromate, metal powder (AI, Cu),
Examples include fired pigments (cobalt blue, green), pearl pigments, etc. Burl pigment is a pigment obtained by coating the surface of a piece of mica with titanium oxide or the like, and is preferable when blended into the paint for metal plates of the present invention since it has the effect of improving the design. For example, Exterior Marlin Bright White (trade name of Marl Corporation), Iriodin 103W2 (
Examples include Merck Japan (product name).

Examples of extender pigments include calcium carbonate, clay, talc, antimony trioxide, barium sulfate, and kaolin.

Examples of the solvent include toluene, xylene, ethyl acetate, butyl acid, cellosolve solvents, methyl isobutyl ketone, methyl ethyl ketone, diisobutyl ketone, isophorone, and cyclohexanone.

Examples of additives include antifoaming agents, pigment dispersants, anti-sagging agents, and anti-scratch agents. Among them, a polytetrafluoroethylene powder resin having a melting point of 30° C. or more is effective as a remarkable anti-scratch agent. For example, Fosterflon TF-9205 (trade name of Hoechst Japan ■) can be mentioned.

Next, a method for producing a coated metal plate using the metal plate paint prepared as described above will be described. As the metal plate to be coated, for example, a hot dip galvanized steel plate, a zinc/aluminum alloy plated steel plate, an aluminum plated steel plate, a cold rolled mesh plate, a stainless steel plate, an aluminum plate, etc. are generally used.

These metal plates are usually degreased before being painted, and in some cases, chemical rust removal such as pickling or electrolytic pickling is performed, followed by chemical conversion coating treatment such as chromate treatment or phosphoric acid treatment. be done.

The paint for metal plates 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 necessary to It is desirable to apply a used undercoat, such as an epoxy resin undercoat, and then bake it.

The viscosity of the paint during application may be a commonly used viscosity, and in the case of roll coating, Ford Cup #4 (25
C) for 40 to 180 seconds.

There are no particular restrictions on the coating method, and methods commonly used for conventional solvent-based coatings, such as brush coating, tampo coating, roll coating, and spray coating, can be used; Roll coating is the most common method of painting. The coating film thickness is in the range of 5 to 80 μm, preferably 10 to 50 μm before baking and hardening.

The baking hardening conditions include heating the metal plate for 15 to 180 seconds to bring the metal plate temperature to 100°C or higher. If the baking time is less than 15 seconds, the curing of the resin component will be insufficient, and if it exceeds 180 seconds, the curing of the resin component will be excessive, and in either case, the original performance of the paint will not be exhibited, which is undesirable.

There are no particular restrictions on the heating method, and any method can be used, including external heating methods such as convection heating and radiation heating, and internal heating methods using high frequency waves.

[Effect]

In the painted metal plate of the present invention, the acrylic polymer beads used in the paint are polymers with a low crosslinking structure containing 2 to 20% by weight of crosslinking agent, and are hardly soluble in solvents and are not too hard. It has intermediate desirable properties. Therefore, without reducing the stability of the paint, and when forming a paint film, the surface layer of the acrylic polymer beads swells slightly and has an affinity with the paint resin component, strengthening its integrity, making the paint film more durable. properties, abrasion resistance,
It is thought that it also contributes to scratch resistance, durability, moisture resistance, etc.

〔Effect of the invention〕

A metal plate coated with the paint of the present invention can obtain a unique finished surface that has not been seen with conventional coated metal plates. In other words, by blending acrylic polymer beads, it gives a matte, textured, soft appearance with excellent design properties, and when molded, the painted surface is tough, scratch resistant, and wear resistant. It also has excellent workability, and the degree of wear on the forming roll surface and shearing blade is very slight.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples. All percentages and parts in the examples are based on weight.

Examples 1 to 6 and Comparative Examples 1 to 3 (Preparation of top coat paints) Each top coat paint was prepared in the following manner according to the formulations in Table 1. As a paint, put Precolor N [L8000 Brown (product name of NOF) into a container and stir while stirring.
Other components were added and mixed uniformly to prepare each top coat.

Below margin *1: Precolor & 8000 Brown (trade name of NOF) The composition and properties of the paint are as follows.

(1) Resin composition (solid content: total 100) Polyvinylidene difluoride 70% (Kynar 500 Nippon Penfort ■ trade name, weight average molecular weight: 65,000
0, melting point 160-165℃) Acrylic resin 30% (methyl methacrylate/ethyl acrylate = 70/3
0, Weight average molecular weight: 6300 (2) Pigment composition (total 1
00) Titanium oxide 3% fired brown 49% fired blank
43% antimony trioxide
5% (3) Pigment/resin (solid content) ratio
0.35 (4) Paint solid content (weight%)
55% (5) Paint viscosity (Ford force / #4.25℃) 105 seconds *2: Techpolymer MBX-3
0 (trade name of Building Blocks Chemical Industry ■, crosslinking agent: 5% by weight, particle size: 30 μmφ) *3: Exterior Marlin Light White (trade name of Marl Co., Ltd.) *4: Fostaflon TF-9205 (Hoechst Japan) ■Product name) *5: Micro Glass Surf Estland REV9 (
(Product name of Nippon Sheet Glass) (Preparation of test piece) The coated plate used was Gallihalium: 55% AI/
A Zn-plated steel plate was used, the back surface of which was previously coated with a back-side paint to a dry coating thickness of 5 μm.

To form a coating film on the front surface, first, apply an epoxy resin paint (product name: Precolor Primer F-1, manufactured by NOF ■) as an undercoat to the surface to be coated using a bar coater #12.
The coating was applied to a dry film thickness of 5 .mu.m, and dried at a final plate temperature of 210.degree. Next, apply each of the above top coats to a dry film thickness of 25 μm using bar coater #46.
It was applied and dried at a final board temperature of 250°C.

The test pieces prepared above were tested using the test items and methods shown below. The results are shown in Table 2.

Margin test method and evaluation method a Paint film appearance: A paint film finish that has a matte texture, softness, warmth, and lacks a metallic feel is rated as having high design (5). On the other hand, those that are hard, cold, and have a metallic feel are rated as low in design (1). Evaluation was made using this 5-point system, and a score of 4 or more was considered to be a pass.

b Pressure mark ゛ Set the temperature of the nibless machine to 40
℃), stacked the front and back sides of two test pieces together, and sandwiched them in a press at a load of 100 kg/cd for 96 hours. was observed with the naked eye. In this test method, the flatter the coating, the
An increase in the number of barbs is observed.

The evaluation method was as follows.

◎: No increase in visual gloss ○: Slight increase in visual gloss is observed.

Δ: An increase in visual gloss is clearly observed.

C Coin scratch resistance: Apply the edge of a 1,000 yen coin to the painted surface of the test piece by pressing it with your finger at an angle of about 45 degrees. While pressing firmly against the painted surface, pull in a direction perpendicular to the plane of the 1,000 yen coin to damage the painted surface. The scratch resistance and slipperiness of the coating film were observed based on the scratches. It was evaluated using the following 5-point method.

◎: Slight scratches.

○: The only scratches are scratch marks.

△: The scratches were only scratch marks, but they reached the undercoat film.

×: Scratches peel off more than scratches.

d Workability: The workability of each specimen was tested in a room at 20°C. 2T in the table means that two coated plates identical to the test specimen to be processed are sandwiched inside (for 3T to 6T, 3 to 6 plates are sandwiched) and bent 180 degrees closely. The bent tip was observed with a 10x magnifying glass to show the level at which it was crack-free. 2T to 5T was considered to be a pass.

e Bottom expansion unit stop ■Blood: 30 x 100an test piece
The sheet is molded 30 times using a roll forming machine,
Thirty sheets were passed through and the plated surface of the roll was observed. The test was carried out using the test pieces of Example 2 and Comparative Examples 1 and 3. The evaluation method was as follows.

◎: No change observed on the surface of the plated surface.

○: The gloss of the plated surface is slightly reduced.

Δ: Decreased gloss of the plated surface was observed.

f plate! Hardness: Pencil hardness was tested based on JIS-D-0202.

g Mengunibani pressure resistance: Taper wear resistance is in accordance with JIS-
Based on 6902, using wear wheel C3-10, load 1
kg, and the wear loss after 1,000 revolutions was measured. The wear loss was evaluated at ■/1.000 revolutions.

hl Sand Binhui: The sand drop test was performed based on ASTM-D96851 up to the exposure of the substrate.

i Salt syrup 11: 2 according to J I S-Z~2371
The T-processed test piece was tested for 2,000 hours, and the degree of rust in the processed area was visually determined.

j Chemical resistance: 3T processed test piece was heated to 10°C at 20°C.
% hydrochloric acid aqueous solution, 10% sulfuric acid aqueous solution, and 10% sodium hydroxide aqueous solution for 10 days, respectively.
The presence or absence of any abnormality in the coating film in the processed area was visually determined.

k Accelerated elongation property: A test piece with 3T processing was tested for 1,500 hours using the following test device and test conditions (commonly known as Ducycle Sunshine Weather-O-meter) Test device: WEL-5unshine-D C, Suga Test Test conditions: Light source carbon arc press temperature 63℃ Observe the painted surface condition after the test, and check the color difference △E between before and after the test.
% gloss retention was measured.

As is clear from Table 2, Comparative Example 1.2, which falls outside the scope of the present invention, has some unsatisfactory points in terms of coating film appearance, pre-stain marks, and forming roll abrasion properties. In Comparative Example 3, in which glass fiber was blended, there was some concern about the abrasion of the forming roll, and the design was poorer than in the Examples. It is clear that Examples 1 to 6 according to the present invention showed extremely good results in terms of coating film appearance, design, coating film toughness, durability, etc.

Procedural author's letter (spontaneous) June 8, 1990 Takashi Hane, Etsu Tani, Tsukasa Sakura, Jun I Nippon Oil & Fats Co., Ltd. 1, Indication of case 1990 Patent Application No. 113718 2, Name of invention Metal Paint for plates and painted metal plates using the same, names
(691) Yodogawa Steel Works Co., Ltd. 4, Agent 653
0 1! (06) 312-4738 Address: 3-21 Suehiro-cho, Kita-ku, Osaka (1) “Detailed Description of the Invention” column of the specification (2) Contents of document amendment proving authority of representation (No. 11 of the specification) "When winding up a metal plate" on page 7, line 11 is corrected to "when winding up a painted metal plate."

(2) The chemical formula from page 8, line 9 to line 12 of page 8 of the specification is amended as follows.

(R: c+ xc, alkyl group) (3) "Exterior armor" on page 10, line 3 of the specification
Correct "Lin Bright White" to "Exterior Marlin Bright White."

(4) “Exterior armor” on page 17, line 4 of the specification
Correct "Lin Bright White" to "Exterior Marlin Bright White."

(5) Supplement the document certifying the authority of representation as attached.

Attached documents (1) Power of attorney: 2 or more copies

Claims (1)

[Scope of Claims] 1. In a paint whose main component is a resin component consisting of polyvinylidene fluoride and an acrylic resin, the solid content of the paint contains acrylic polymer beads containing 2 to 20% by weight of a crosslinking agent. A paint for a metal plate, characterized in that it contains 0.1 to 30% by weight. 2. A top coat film formed by applying the paint according to claim 1,
Painted metal plate formed on the board surface. 3. A method for manufacturing a coated metal plate, which comprises applying the paint according to claim 1 to a metal plate, heating the metal plate to reach a temperature of 100° C. or more, and baking and curing the coating.