WO2007023745A1

WO2007023745A1 - Mirror rear face-coating composition and mirror

Info

Publication number: WO2007023745A1
Application number: PCT/JP2006/316251
Authority: WO
Inventors: Hirokazu Tanaka; Shigeki Tanaka; Yasuo Kotani; Katsuaki Ninomiya
Original assignee: Nippon Sheet Glass Company, Limited; Shinto Paint Co., Ltd.
Priority date: 2005-08-22
Filing date: 2006-08-18
Publication date: 2007-03-01
Also published as: JP4975989B2; JP2007056054A

Abstract

A coating composition for a mirror rear face comprising a binder and a pigment, wherein the content of the pigment in a coating sheet formed using the composition is 5 to 15% by volume and the epoxy resin has an epoxy equivalent of 160 to 3300; and a mirror comprising a glass substrate and a silver mirror sheet, a metal protection coating sheet, and a rear face protection coating sheet laminated on the glass substrate in this order, wherein the content of the pigment in the rear face protection coating sheet is 5 to 15% by weight and the epoxy resin has an epoxy equivalent of 160 to 3300. The mirror shows excellent corrosion resistance, chemical resistance and the like without using lead as the pigment, and can retain a good mirror quality stably for a long period even in a severe use environment.

Description

Specification

Mirror backside coating composition and mirror

Technical field

TECHNICAL FIELD [0001] The present invention relates to a coating composition for forming a back surface protective coating film in a mirror in which a silver mirror film, a metal protective film and a back surface protective coating film are laminated on a glass substrate. Excellent in chemicals and chemical resistance, and even in harsh usage environments, it contains virtually no lead compounds for the formation of back surface protective coatings that can stably obtain good mirror quality for a long period of time! The present invention relates to a composition and a mirror using the coating composition as a back surface protective coating film.

Background art

[0002] Mirrors reflect visible light and the like on a silver mirror surface, and are used in ordinary homes and offices. The backside protective coating film provides resistance to chemicals such as water, various gases, acids, and alkalis according to the usage environment of the mirror, as well as to increase mechanical strength and prevent damage. To be applied. Paints for forming the backside protective coating include lacquer, alkyd resin, epoxy resin, and other binders. In the past, those containing lead pigments such as these have been widely used.

Lead-based pigments formulated as anticorrosives usually have a function of suppressing ionization and alteration of silver, copper, etc. by lead, which has a higher ionization tendency than metals such as silver and copper used in mirrors. The interface with the metal film serves as a reducing atmosphere, and has a function of preventing the oxidation of the metal film. Furthermore, the basic substance generated from the lead-based pigment neutralizes the acidity of the corroded part and prevents the oxidation of the metal film, and the lead-based pigment force elutes anions such as cyanamide and metal ions derived from the metal film. It has the function of reacting to form a passive film and preventing corrosion of the metal film.It has also been performed by using two-component epoxy resin as a binder for the purpose of improving chemical resistance. .

[0003] However, in recent years, from the viewpoint of environmental protection from pollution and hygiene, it has been required to reduce the lead content in the pigment and to make it lead-free without containing lead. Has been made. For example, a mirror in which a silver mirror film, a metal protective layer, and a backing coating layer are formed on a glass substrate, and the backing coating layer is applied and cured with a coating composition containing an epoxy resin and a curing agent imidazole derivative. Improved mirror (Patent Documents 1 and 2, refer to the scope of patent request), and a coating composition containing an epoxy resin and a curing agent aminotriazole or dicyandiamide as a backing coating layer and cured. An improved mirror (see Patent Document 3, claims) is proposed.

However, these improved mirrors have poor chemical resistance, particularly acid resistance, as compared to conventional mirrors having a backing coating layer using a lead-containing coating composition. This is probably because the water permeability increased and the chemical resistance deteriorated as a result of suppressing the amount of the epoxy resin component in the coating film in order to obtain corrosion resistance, workability and durability.

Further, in a mirror in which a silver mirror film, a metal protective film, and a back surface protective film are sequentially laminated on a glass substrate, the back surface protective film contains a pigment (P ) And binder (B) consisting of 40 to 85 parts by weight of epoxy resin and hardener and 15 to 60 parts by weight of ketone formaldehyde resin and its derivatives (PZB) is 1.2 to 4. A mirror has been proposed in which a coating consisting of 0 is applied and cured (see Patent Document 4 and Claims). However, the mirror proposed here has a high water permeability of the coating film due to the low content of the epoxy resin used for the protective film on the back surface.For example, the coating film is used in a high humidity environment such as a bathroom. Moisture that has passed through the surface may corrode the silver mirror film, so-called surface corrosion.

[0004] Patent Document 1: Japanese Patent Laid-Open No. 6-284948

Patent Document 2: JP-A-6-277138

Patent Document 3: Japanese Patent Laid-Open No. 6-253963

Patent Document 4: Japanese Patent Laid-Open No. 7-13006

Disclosure of the invention

[0005] In view of the above-mentioned problems, the object of the present invention is excellent in corrosion resistance, chemical resistance, etc. without using a lead-based pigment as a pigment, and has a good quality as a mirror even in a severe use environment. The present invention provides a coating composition for forming a back surface protective coating obtained by stabilizing for a long period of time, and a mirror using the coating composition for the back surface protective coating. [0006] As a result of intensive studies to achieve the above object, the inventors of the present invention have developed a coating composition for mirror back surface containing a binder and a pigment, in a coating film formed by the coating composition. It has been found that a coating composition for a mirror back surface with a pigment volume concentration in a specific range can solve the above problems. The present invention has been completed on the basis of strong knowledge.

That is, the present invention provides:

(1) A coating composition for a mirror back surface containing a binder and a pigment, wherein the binder is an epoxy resin and a curing agent, and the pigment volume concentration in the coating film obtained using the composition is 5 to 15 %, And the coating composition for the back of the mirror whose epoxy equivalent of epoxy resin is 160-3300, and

(2) A mirror in which a silver mirror film, a metal protective film, and a back surface protective coating film are sequentially laminated on a glass substrate, and the back surface protective coating film contains a binder and a pigment such as an epoxy resin and a curing agent. The coating composition for mirror back surface is applied, the pigment volume concentration in the back surface protective coating film is 5 to 15%, and the epoxy equivalent of epoxy resin is 160 to 3300 Mirror.

[0008] According to the present invention, the back surface is excellent in corrosion resistance, chemical resistance, etc. without using a lead-containing compound as a pigment, and can stably obtain a good quality as a mirror for a long period of time even in a severe use environment. A coating composition for forming a protective coating film and a mirror using the coating composition as a back surface protective coating can be produced.

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] The coating composition for mirror back surface of the present invention comprises a needle and a pigment. Various types of rosin can be used as the noder, but it is also preferable to have epoxy resin and hardener power. Epoxy resins having an epoxy equivalent of 160-3300 are preferred, such as bisphenol A type, bisphenol F type epoxy resins, hydrogenated epoxy resins, alicyclic epoxy resins, etc. Among them, bisphenol type epoxy resin can be preferably used. Commercially available from Mitsui Chemicals, Epomic R301, 3002, 304, 307, Asahi Kasei Chemicals, AER # 661, 662, 664, 66 7 669, manufactured by Asahi Denki Co., Ltd., Adeka Resin EP-5100, 5400, 5700, 5900, 4100, Janon Epoxy Resin Co., Ltd. 007, 1009, 815, 825, 828, etc. can be selected as appropriate.

[0010] As the curing agent for epoxy resin, those used for ordinary epoxy resin curing agents such as amines and acid anhydrides can be used without any problem, and among them, amine curing agents can be preferably used. The Specific examples include aromatic amine curing agents, aliphatic amine amine curing agents, amidopolyamine curing agents, polyamide curing agents, and the like. Commercially available curing agents include Fuji Kasei Kogyo ( Toomide 410N, 215-70 X, ST-23, Daito Industries, Ltd. Daitokurar HD-325, D-677, HD-801CB, M-154 0, P-4730, manufactured by Air Products Japan, Inc., Sunmide 153-60S, X-2700-49, X-2015, E-1001, Ancamin 2143, 1618, Ancamide 350A, etc.

[0011] Regarding the pigment used in the present invention, those usually used for the mirror back surface coating composition can be used without any problem. For example, an extender pigment, a coloring pigment, an antifungal pigment, and the like are combined. Can do.

The extender pigment can be selected from those used in ordinary paints according to the chemical resistance, heat resistance, etc. of the pigment itself. For example, talc, barium sulfate, magnesium silicate, my strength, Selected from kaolin, calcium carbonate and the like.

Color pigments can be selected from those used in ordinary paints according to the chemical resistance, heat resistance, etc. of the pigment itself, such as titanium oxide, carbon black, black iron oxide, and second oxide. Iron, yellow ferric, chlorinated phthalocyanine green, odor chlorinated lid mouth cyanine green, phthalocyanine blue, etc. are also selected.

The anti-glare pigment is not particularly limited as long as it is a lead-free type among those used as ordinary paints, and can be appropriately selected according to the chemical resistance, heat resistance, etc. of the pigment itself. Specifically, zinc oxide, zinc phosphate, zinc polyphosphate, calcium phosphate, calcium zinc phosphate, aluminum phosphate, magnesium phosphate, zinc phosphite, zinc molybdate, zinc calcium molybdate, calcium molybdate, Zinc phosphomolybdate, calcium phosphomolybdate, aluminum phosphomolybdate, aluminum zinc phosphomolybdate, cyanamide zinc, calcium cyanamide zinc, barium metaborate and the like can be selected. [0012] In the solid content in the coating composition, the content of the epoxy resin is not particularly limited as long as the pigment volume concentration in the coating film is in the range of 5 to 15%. Although it depends mainly on the density of the pigment to be used, it is usually desirable that the content of the pigments including 55 to 70% by weight and the extender pigments, coloring pigments and antifouling pigments is 20 to 40% by weight. The amount of the epoxy resin hardener is appropriately determined depending on the type of epoxy resin, epoxy equivalent, and the amount of epoxy resin, but it should be 5 to 15% by weight in the solid content of the coating composition. Is desirable.

[0013] The coating composition of the present invention is characterized in that the pigment volume concentration in the coating film obtained by using the composition is 5 to 15%, and when the pigment volume concentration is lower than 5%, the coating film Becomes softer and the mirror releasability becomes worse. On the other hand, if the pigment volume concentration exceeds 15%, the coating film easily allows chemicals such as acids to permeate, and the chemical resistance such as acid resistance decreases.

[0014] In the coating composition of the present invention, a solvent can be used for dissolving a binder or a curing agent in order to obtain appropriate pigment dispersion and coating workability. An appropriate amount of a known solvent such as an aromatic or aliphatic hydrocarbon, ester, ether, ketone, ester ether, or alcohol can be used. In addition, additives such as dispersants, anti-settling agents, antifoaming agents, surface conditioners, surfactants, etc., which are usually used in coating compositions for improving workability and the appearance of the coating film can be used. Needless to say.

[0015] Next, the mirror of the present invention will be described in detail below. The mirror of the present invention is a mirror in which a silver mirror film, a metal protective film, and a mirror back protective film are sequentially laminated on a glass substrate in the same manner as a normal mirror. Needless to say, the coating film for mirror back surface is a dry coating film obtained from the coating composition for mirror back surface of the present invention. The glass substrate used here is not particularly limited, but the use of soda lime plate glass is most preferable from the viewpoint of economy.

[0016] The silver mirror film in the present invention is formed on a glass substrate by a chemical plating method using a so-called silver mirror reaction, a vacuum deposition method, or other known physical and chemical film formation methods. Thickness should be in the range of 60 ~: LOOnm! / ,.

The film thickness of the silver mirror film is preferably 60 nm or more. The reason is that the silver mirror film needs to have a sufficient reflectivity in almost all the wavelength range of incident visible light. This is because the reflectivity may be insufficient if it is less than Onm. The silver mirror film thickness is 10 The reason why the thickness is preferably Onm or less is not particularly limited from the viewpoint of reflectivity, but if the film thickness is larger than necessary, the manufacturing cost increases.

[0017] Further, the metal protective film is designed to prevent corrosion of the silver mirror film by using copper, tin, or an alloy thereof having a higher ionization tendency than silver and being eroded by itself. . Similarly to the silver mirror film, the metal protective film is preferably formed to a film thickness of 20 to 50 nm by chemical plating or other film forming methods.

The reason why the thickness of the metal protective film is preferably 20 nm or more is that when the film thickness is 20 nm or less, the adhesion to the silver mirror film is inferior and the silver mirror film may be insufficiently protected. Moreover, the reason why the thickness of the metal protective film is preferably 50 nm or less is that although there is no particular upper limit to the viewpoint of protecting the silver mirror film, if the film thickness is larger than necessary, the manufacturing cost increases.

Example

Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Evaluation methods

The mirrors obtained in each Example and Comparative Example were evaluated by the following methods.

(1) Film thickness of coating film: Measured by using a stylus step gauge ("Dial Depth Gauge" manufactured by Teclock Corporation).

(2) Pencil hardness: Measured according to JIS K5600-5-4.

(3) Adhesiveness: The force cut number according to JIS K5600-5-6 was set to 11 in each direction, and the interval was lmm. The cellophane tape was pressure-bonded to the cell and immediately peeled off, and the number of cells remaining was evaluated. The number of remaining squares is expressed as Z100.

(4) Detachability: The glass was cut with a cutter on the side of the glass surface of the mirror, and the releasability of the coating film for the back of the mirror was evaluated. When the coating film can be cut together with the glass part and the cut edge of the coating film can be cut in a straight line, the coating film cannot be cut, or the cut edge is not linear even if it can be cut, or peeling or floating occurs Was regarded as defective.

(5) Acid resistance: Aqua regia having the composition shown in Table 1 was prepared, and the state of the coating film was visually observed after the entire mirror was immersed in the aqua regia for 10 days at room temperature. Good with strong corrosion resistance A case where the coating film was corroded and a part or all of the coating film was peeled off was regarded as defective.

(6) Salt spray resistance; evaluated according to JIS K-5600-7-1. The test piece was cut out from a 100 x 75 mm mirror, and a marking line reaching the substrate (glass) was put in each diagonal direction from the back protective coating side (hereinafter referred to as “cross-cut section”) using a phonograph. After exposure to the salt spray test for 250 hours continuously, the progress of corrosion on the cross-cut silver mirror film was observed, and the corrosion width was measured. In addition, the state of the mirror surface other than the cross-cut portion was visually observed, and the case where there was no change in the reflection surface before and after the saltwater spray test was considered good.

(7) Cast test: The test was performed in accordance with JIS H8681-2. A 100 × 75 mm mirror was cut out, and the two long sides were lightly rubbed with sandpaper and used as the side for observing the vignetting width. The mirror was exposed for 5 consecutive days at 50 ± 2 ° C. in a 5% saline spray (acetic acid salt water spray containing copper salt) atmosphere. The corrosion width from the observation side to the silver mirror film was observed and measured from the mirror surface (denoted as pitting corrosion in the table). In addition, the state of the mirror surface (general surface) other than the peripheral edge was visually observed, and the case where there was no change in the reflection surface before and after the test was determined to be good.

[table 1]

table 1

Examples 1-3 and Comparative Examples 1-4

(1) Preparation of coating composition for mirror back

Based on the formulation described in Table 2, a base material for a mirror back surface was prepared by a conventional method. The solvent used was a mixed solvent of xylene / butyl solvate, and the mixing ratio was 4: 6 by weight. Moreover, the curing agent shown in Table 2 was dissolved in the same mixed solvent to obtain a curing agent solution. Next, the base and the curing agent solution were mixed and stirred at the ratios shown in Table 2 to obtain a coating composition for the mirror back surface. In addition, each compounding quantity of a base material and a hardening | curing agent is represented by weight%.

(2) Mirror production A glass substrate (made by Nippon Sheet Glass, size 1830mm X 915mmX 5mm) is thoroughly cleaned by brushing, and a silver mirror reaction is performed on one side of the glass substrate by a conventional method (a solution containing silver nitrate that precipitates silver and reducing silver). A silver plating solution was then sprayed with the reducing solution to form an 80 nm silver mirror film. After the surface of the film was washed with water, a copper metal protective film having a thickness of 30 nm was formed by copper using an electroless plating method. Thereafter, it was washed again with water and dried.

On the copper protective film of the glass substrate on which the silver mirror film and the copper protective film are formed, the mirror back surface composition prepared in (1) is applied by a flow coater method so that the dry film thickness is 50 m. Subsequently, the glass substrate was baked for 20 minutes so that the temperature of the glass substrate was 170 ° C., and a mirror was produced. Table 3 shows the evaluation results of the mirrors produced in each example and comparative example.

[Table 2]

Table 2

Examples Comparative examples

Ingredient 1 2 3 1 2 3 4 Base material Binder epoxy resin '1.2 34 41 32 30 50 —— ———

(Mass ¹ ½)

Epoxy resin B * ² 1.2 —One — —— —— ——One 38 —— Alkyd resin ”1.1 —— —— —— ——— ——— One one— 30 Melamine resin * ⁴ 1.1 —One —— — -------6 Pigment Talc 2.7 5-5 5 --- 5 5 Barium sulfate 4.3 3 1 4.5 7 ——— 3 3 Yellow iron oxide 4.0 1 1 1 1 1 1 1 Titanium oxide 4.3 1.87 1.87 1.87 1.87 1.87 1.87 1.87 Car pump hook 1.8 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Odor chlorinated lid

Cyanine Green 1.6 0.03 0.03 0.03 0.03 0.03 0.03 0.03 Zinc oxide 5.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 Acrylic surface

Additive 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Tension modifier ^t5

Xylene, butyl

Solvent-39.00 37.56 39.91 39.83 27.71 40.1 1 44.00 Cellosolve

Hardener Aliphatic amine hardener W 1.1 5.00 6.03 4.71 4.41 7.35 1.35 —— Xylene, butyl

Solvent-2.00 2.41 1.88 1.76 2.94 0.54--Cellosolve

Total (<½) 100 100 100 100 100 100 100 Epoxy resin solids (%) 57.6 68.3 55.0 51.4 72.1 64.0 ―— Pigment solids (%) 33.1 20.8 36.1 40.2 16.6 32.9 34.8 Additive solids (<½) 0.8 0.8 0.9 0.9 0.7 0.8 0.9 Pigment volume concentration (<½) 12.7 5.9 14.2 16.4 4.5 12.7 12.7 [0022] * 1 Epoxy resin A: “Epicoat # 1004” (epoxy equivalent 940) manufactured by Japan Epoxy Resin Co., Ltd.

* 2 Epoxy resin B: Japan Epoxy Resin Co., Ltd. “Epicoat # 1010” (epoxy equivalent 4000)

* 3 Alkyd resin; “Atari Reset AZ— X 663— X 50” manufactured by Nippon Shokubai Co., Ltd.

* 4 Melamine oil; “Melan 265” manufactured by Hitachi Chemical Co., Ltd.

* 5 Acrylic surface tension modifier; “Miki Leveling MK Conch” manufactured by Kyoeisha Igaku Co., Ltd.

* 6 Aliphatic amine-based curing agent; “Daitoclar D-677” manufactured by Daito Sangyo Co., Ltd.

[0023] [Table 3]

Table 3

Industrial applicability

[0024] According to the present invention, the back surface protection can be stably obtained with good quality as a mirror for a long period of time even in a harsh usage environment, excellent in corrosion resistance and chemical resistance without using lead as a pigment. A coating composition for forming a coating film and a mirror using the coating composition as a back protective coating film can be provided.

Claims

The scope of the claims

[1] A coating composition for mirror back surface comprising a noinder and a pigment, wherein the binder comprises an epoxy resin and a curing agent, and the pigment volume concentration in the coating film obtained using the composition is 5 to 15%. And a coating composition for a mirror back surface, wherein the epoxy equivalent of the epoxy resin is 160-3300.

[2] A mirror in which a silver mirror film, a metal protective film, and a back surface protective coating film are sequentially laminated on a glass substrate, and the back surface protective coating film includes a binder and a pigment such as an epoxy resin and a curing agent. A mirror obtained by applying a coating composition for a back surface of a mirror, wherein the pigment volume concentration in the back surface protective coating film is 5 to 15%, and the epoxy equivalent of the epoxy resin is 160 to 3300.