JPH06166847A - Hard coat - Google Patents

Abstract

PURPOSE:To obtain a hard coat excellent in scratch resistance, transparency, heat resistance, weather resistance and adhesion. CONSTITUTION:This hard coat is prepared by applying a primer comprising a coating composition obtained by adding a curing catalyst to a mixture comprising an alkoxysilane (a), a hydroxy(meth)acrylate copolymer (b) and an organic solvent (c) in a weight ratio of (a) to (b) of 1/0 to below 1/3 and hydrolyzing the mixture to a substrate and applying an overcoating agent comprising a coating composition obtained by adding a curing catalyst to a mixture comprising an alkoxysilane (a), a hydroxy(meth)acrylate copolymer (b) and an organic solvent (c) in a weight ratio of (a) to (b) of 1/3 to 1/20 and hydrolyzing the mixture to the primer coat.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to hard coats and more particularly to scratch resistance formed on the surface of plastics, wood, cement, iron, stainless steel, aluminum and other metals, and other products. The present invention relates to a hard coat excellent in transparency, heat resistance, weather resistance and adhesion.

[0002]

2. Description of the Related Art Hitherto, as a coating composition for improving scratch resistance, it has been disclosed in JP-A-53-2565.
JP-A-56-22365 and JP-A-61-1668.
No. 24, etc., there is a method using a hydrolyzate of alkoxysilane. In addition, as a coating composition containing organoalkoxysilane and colloidal silica or colloidal alumina as main components, Japanese Patent Publication No. 52-39691.
No. 5, Japanese Patent Publication No. 53-5042, Japanese Patent Laid-Open No. 54-87736.
JP-A-55-94971, JP-A-56-9923
6, the method according to JP-A-59-68377, and the like.

Furthermore, as a coating composition obtained by curing an acrylic copolymer containing an alkoxysilyl group, JP-A-3-47871 and JP-A-3-3787 are available.
-54278 etc. are mentioned. However, when these coating compositions were used, there were drawbacks such as scratch resistance of the obtained hard coat layer, adhesion to the substrate, and poor storage stability of the solution.

[0004]

In view of the above circumstances, it is an object of the present invention to provide a hard coat having excellent scratch resistance, transparency, heat resistance, weather resistance and adhesion.

[0005]

Means for Solving the Problems In the present invention, as a result of extensive studies to solve the above problems, a specific hydroxy (meth) acrylate copolymer and an alkoxysilane were mixed in a specific ratio and hydrolyzed. The inventors have found that the above objects can be achieved by using the above products, and have reached the present invention.

That is, the gist of the present invention resides in a hard coat obtained by applying a primer comprising the following coating composition onto a substrate, and then applying an overcoat comprising the following coating composition thereon. Primer: alkoxysilane (1), hydroxy (meth) acrylate copolymer (2) and organic solvent (3)
A coating composition obtained by adding the curing catalyst (4) to the mixture and hydrolyzing the mixture, which comprises (1) / (2) is 1/0 or more and less than 1/3 (weight ratio).

Overcoat: consisting of alkoxysilane (1), hydroxy (meth) acrylate copolymer (2) and organic solvent (3), and (1) /
A coating composition obtained by adding a curing catalyst (4) to a mixture in which (2) is 1/3 or more and 1/20 or less (weight ratio) and hydrolyzing the mixture. Hereinafter, the present invention will be described in detail.

The alkoxysilane (1) used in the present invention is not particularly limited, but tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetraptoxysilane, tetraphenoxysilane and the like, and 50 to 60% thereof. Hydrolysis products of Preferably, a silicate oligomer represented by the following general formula (I) is used.

[0009]

[Chemical 2]

(N represents an integer of 1 to 20. R represents a true or branched alkyl group having 1 to 6 carbon atoms or an aryl group. Of R, CH ₃ and C ₂ are preferable.
H _5, C ₃ H _7, is _{C 4 H 9, C 6 H} 5. ) The hydroxy (meth) acrylate copolymer (2) used in the present invention is not particularly limited as long as it is an acrylic copolymer containing a hydroxy (meth) acrylate component, but as a condition compatible with the silicate oligomer, It is important to have a hydroxyl group in the copolymer. Preferably, it is a copolymer of at least one selected from a hydroxy acrylate component and a hydroxy methacrylate component and at least one selected from a methacrylic acid ester component and an acrylic acid ester component.

The hydroxy acrylates which give the hydroxy acrylate component include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and 4
-Hydroxybutyl acrylate and the like can be mentioned. As hydroxymethacrylate that gives a hydroxymethacrylate component, 2-hydroxyethylmethacrylate, 2-hydroxypropylmethacrylate, 4-hydroxymethacrylate
Examples thereof include hydroxybutyl methacrylate.

Further, as the methacrylic acid ester which gives the methacrylic acid ester component, methyl methacrylate,
Examples thereof include ethyl methacrylate, butyl methacrylate, lauryl methacrylate and the like. Examples of the acrylate ester that provides the acrylate component include methyl acrylate, ethyl acrylate, butyl acrylate, and lauryl acrylate.

The hydroxyacrylate component and / or hydroxymethacrylate component is preferably 1 to 20% by weight, and the methacrylic acid ester component and / or acrylic acid ester component is preferably 80 to 99% by weight in the copolymer. If the hydroxyacrylate component or hydroxymethacrylate component is less than 1% by weight, the transparency will be poor, and if it exceeds 20% by weight, the hardness will be lowered and the abrasion resistance will be poor, such being undesirable.

The methacrylic acid ester component and the acrylic acid ester component may be used alone, but are preferably used in combination. When used in combination, the ratio of the methacrylic acid ester component to the acrylic acid ester component is such that the methacrylic acid ester component: acrylic acid ester component = 2: 1 to 1:
5, preferably 1: 1 to 1: 3, particularly preferably about 1:
2 (weight ratio). Further, after the coating composition of the present invention is hydrolyzed and coated, when a coating film is formed, the glass of the copolymer is used in order to prevent curing shrinkage and internal stress, which causes problems such as cracking of the coating film. It is necessary to set the transition temperature low.

A desirable glass transition temperature for this purpose is -20 ° C to 40 ° C, and it is necessary to select an acrylic composition so as to fall within this range. Such a copolymer can be easily synthesized by radical polymerization. The organic solvent (3) that can be used varies depending on the material of the substrate to be coated, but for example, alcohols, glycol derivatives, hydrocarbons, esters, ketones, ethers, or a mixture of two or more thereof. Can be used.

Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, and octanol, and examples of glycol derivatives include ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene. Examples thereof include glycol mono n-propyl ether and ethylene glycol mono n-butyl ether.

The hydrocarbons include benzene, kerosene,
Toluene, xylene, etc. can be used, and as esters,
Methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, ethyl acetoacetate and the like can be used. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and acetylacetone, and ethers such as ethyl ether, butyl ether, z-methyl cellosolve, ethyl cellosolve, dioxane, furan and tetrahydrofuran can be used.

The amount of the organic solvent used is preferably about 1 to 10 times the weight of the organic solvent-soluble resin in terms of operability. The curing catalyst (4) is, for example, hydrochloric acid,
Inorganic acids such as acetic acid, nitric acid, formic acid, sulfuric acid and phosphoric acid, organic acids such as paratoluene sulfonic acid, benzoic acid and phthalic acid,
Organotin compounds such as dibutyltin dilaurylate, dibutyltin dioctiate, dibutyltin diacetate,
Alkali catalysts such as potassium hydroxide and sodium hydroxide are effective, but inorganic acids, organic tin compounds and organic acids are particularly effective.

The hard coat of the present invention is based on a primer comprising a coating composition obtained by hydrolyzing a mixture of the above-mentioned alkoxysilane, hydroxy (meth) acrylate copolymer and organic solvent in the presence of a curing catalyst. It is applied on a material, and an overcoat made of the same coating composition is applied thereon.

As the primer of the present invention, the weight ratio (1) / (2) of the alkoxysilane (1) and the hydroxy (meth) acrylate copolymer (2) is 1/0 or more and 1/3.
It is less than 1, preferably in the range of 1/0 to 1/2. If there is no primer, there arises a problem that the adhesion to the overcoat is slightly lowered. Also, (1) /
If (2) is ⅓ or more, there arises a problem that the adhesiveness to the base material is lowered when the base material is plastic or stainless steel.

In the case of an overcoat, the weight ratio (1) / (2) of alkoxysilane (1) to hydroxy (meth) acrylate copolymer (2) is 1/3 or more and 1/20.
The range is preferably 1/3 or more and 1/10 or less. If (1) / (2) is smaller than 1/3, the abrasion resistance by the Taber abrasion test is not sufficient, and if it is larger than 1/20, curing shrinkage occurs after heating and curing, and thus adhesion to the plummer. Undesirably occurs.

More specifically, the method for producing the coating composition used in the present invention will be described. First, for the production of the primer, a hydroxy (meth) acrylate copolymer and an alkoxysilane are preferably used in an organic solvent, preferably the above-mentioned general. A method in which a silicate oligomer represented by the formula (I) is added and an acid such as hydrochloric acid, dibutyltin dilaurate, or paratoluenesulfonic acid is added to carry out the hydrolysis reaction can be mentioned.

The overcoat is produced by adding a hydroxy (meth) acrylate copolymer and an alkoxysilane to an organic solvent in the same manner as in the method of producing a primer.
A method of adding an acid such as hydrochloric acid, dibutyltin dilaurate, or paratoluenesulfonic acid to carry out the hydrolysis reaction can be mentioned. For the hard coat of the present invention, first, a primer is applied and dried at 18 to 30 ° C. for 30 minutes, then an overcoat is applied and dried at 18 to 30 ° C. for 30 minutes, and then 120 ° C.
It is obtained by curing for 1 hour.

The base material to which the hard coat obtained by the present invention can be applied includes plastic, wood, cement, iron, stainless steel, aluminum and other metals. For the hard coat obtained by the present invention, a coating means such as a brush, spin coat spray, dipping, roll, or gravure printing method can be used on the surface of the object. At this time, the film thickness of the formed film is usually about 0.1 to 50 μm, preferably 0.1 to 20 μm.
It is a degree. If it is less than 0.1 μm, sufficient scratch resistance cannot be obtained, and if it is more than 50 μm, the film is likely to be cracked.

[0025]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In the following examples, all "parts" are "parts by weight".

<Synthesis of acrylic resin (I)> Tetrahydrofuran 1425 using a 3000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer.
After 164 g of methyl methacrylate, 300 g of ethyl acrylate, and 27 g of 2-hydroxyethyl acrylate were added to g, the mixture was stirred. After heating the solution to 65 ° C,
A solution prepared by dissolving 7.5 g of 2,2′-azobisisobutylnitrile in 75 g of tetrahydrofuran was added dropwise, and 6
The mixture was stirred at 5 ° C for 7 hours. After distilling off the tetrahydrofuran, it was dried to obtain an acrylic resin (I).

<Synthesis of acrylic resin (II)> Tetrahydrofuran 1425 was used using a 3000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer.
After 491 g of methyl methacrylate was added to g, the mixture was stirred. After the temperature of the solution was raised to 65 ° C., 7.5 g of 2,2′-azobisisobutylnitrile was added to tetrahydrofuran 7
What was dissolved in 5 g was added dropwise, and the mixture was stirred at 65 ° C. for 7 hours. After removing the tetrahydrofuran by distillation, drying was performed to obtain an acrylic resin (II).

<Synthesis of acrylic resin (III)> Tetrahydrofuran 1425 was used using a 3000 ml separable flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer.
After 343 g of methyl methacrylate and 148 g of ethyl acrylate were added to g, the mixture was stirred. After raising the temperature of the solution to 65 ° C., 2,2′-azobisisobutylnitrile 7.
What melt | dissolved 5 g in 75 g of tetrahydrofuran was dripped, and it stirred at 65 degreeC for 7 hours. After the tetrahydrofuran was distilled off, the residue was dried to obtain an acrylic resin (III).

<Preparation of Coating Liquid (I) for Primer> 10 equipped with a nitrogen inlet tube, a reflux condenser and a stirrer
Using a 0 ml four-necked flask, 5 g of acrylic resin (I) was added to 15 g of ethanol and dissolved at 65 ° C.
To this was added 5 g of MS-51 (trade name, MKC silicate MS51 manufactured by Mitsubishi Kasei Co., Ltd .: a product obtained by hydrolyzing 50% of tetramethoxysilane). 1N HC in this solution
0.95 g of 1 was added and stirred at 65 ° C. for 30 minutes to prepare the coating liquid (I) for primer.

<Preparation of Coating Liquid (II) for Primer> 10 equipped with a nitrogen introducing pipe, a reflux condenser and a stirrer
Using a 0 ml four-necked flask, add 5 g of the acrylic alcohol-soluble resin (I) to 15 g of ethanol, and add 65
Dissolved at ° C. 20 g of MS-51 was added to this.
3.8 g of 1N HCl was added to this solution, and the mixture was stirred at 65 ° C. for 30 minutes to prepare a coating liquid (II) for primer.

<Example 1> (Coating of primer) A coating solution (I) for primer was used as a polycarbonate solution (manufactured by Mitsubishi Kasei Co., Ltd. 1
(00 mm × 100 mm × 2 mm) using a # 8 bar coater, and dried at 20 ° C. for 30 minutes. (Coating of overcoat) Using a 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer, 5 g of acrylic resin (I) was added to 30 g of ethanol and dissolved at 65 ° C. Add MS-51 to this
g was added. After adding 2.47 g of water to this solution, 1N
2.38 g of HCl was added and the mixture was stirred at 65 ° C. for 1 hour. This solution was applied to the above-mentioned primer-coated polycarbonate plate using a # 10 bar coater,
After drying at 20 ° C. for 30 minutes, it was cured at 120 ° C. for 1 hour.

The total light transmittance and haze are JIS K-71.
When measured according to 05, 92%,
The transparency was as good as 0.5%. (Base material polycarbonate plate thickness 2 mm) Further, in order to test the degree of scratches, a Taber-type wear test (wear wheel CS-10F, 50) was used.
When subjected to 0 g load and 100 rotations), the change in haze was 5% and the scratch resistance was excellent.

11 parallel and 11 vertical and horizontal lines perpendicular to the center of the coating film surface were drawn at intervals of 1 mm until reaching the substrate surface, and a grid pattern was formed so that 100 squares could be formed in 1 cm ² . . Stick cellophane adhesive tape (product name cellophane tape manufactured by Nichiban Co., Ltd.) firmly on the grid and press 90
It was peeled off rapidly in the direction of the angle, and the presence or absence of peeling of the coating film was examined. 100/100 when the number of films that did not peel
The adhesion was also good.

Example 2 (Coating with Primer) A polycarbonate plate (100 mm × 100 mm × 2 mm) was coated in the same manner as in Example 1. (Coating of overcoat) Using a 100 ml four-necked flask equipped with a nitrogen inlet tube, a reflux condenser and a stirrer, 5 g of acrylic resin (I) was added to 40 g of ethanol and dissolved at 65 ° C. MS-51 35
g was added. After adding 3.20 g of water to this solution, 1N
3.33 g of HCl was added, and the mixture was stirred at 65 ° C. for 30 minutes. This solution was applied to the polycarbonate plate coated with the above primer using a # 10 bar coater, and 2
After drying at 0 ° C. for 30 minutes, it was cured at 120 ° C. for 1 hour.

When the total light transmittance and the haze were measured in the same manner as in Example 1, the transparency was 91% and 0.5%, respectively, indicating good transparency. (Base material polycarbonate plate thickness 2 mm) When this coating film was tested and evaluated in the same manner as in Example 1, the change in haze was 3% and the scratch resistance was excellent. When a paint film peeling test was conducted in the same manner as in Example 1, the adhesion was 100/100 and the adhesion was good.

Example 3 (Coating with Primer) A polycarbonate plate (100 mm × 100 mm × 2 mm) was coated in the same manner as in Example 1. (Coating of overcoat) Using a 100 ml four-necked flask equipped with a nitrogen introduction tube, a reflux condenser and a stirrer, 5 g of acrylic system (I) was added to 50 g of ethanol.
The mixture was added and dissolved at 65 ° C. To this, 45 g of MS-51 was added. After adding 4.12 g of water to this solution, 1 NHC
4.28 g of 1 was added and stirred at 65 ° C. for 30 minutes. The solution was applied to the above-mentioned primer-coated polycarbonate plate using a # 10 bar coater,
After drying at 30 ° C. for 30 minutes, it was cured at 120 ° C. for 1 hour.

When the total light transmittance and the haze were measured in the same manner as in Example 1, the transparency was good at 91% and 0.5%. (Base material polycarbonate plate thickness 2 mm) When this coating film was tested and evaluated in the same manner as in Example 1, the change in haze was 2% and the scratch resistance was excellent. When a paint film peeling test was conducted in the same manner as in Example 1, the adhesion was 100/100 and the adhesion was good.

<Example 4> (Coating of primer) The coating solution (I) for primer was applied to a polymethylmethacrylate plate (100 mm).
× 100 mm × 2 mm) using a # 8 bar coater, and dried at 20 ° C. for 30 minutes. (Overcoat coating) Overcoat coating and curing were performed in the same manner as in Example 1 except that the above-described primer-coated polymethylmethacrylate plate was used.

When the total light transmittance and the haze were measured in the same manner as in Example 1, the transparency was 94% and 0.4%, which was a good transparency. (Base material polymethylmethacrylate plate thickness 2 mm)
When this coating film was tested and evaluated for the degree of scratches in the same manner as in Example 1, the change in haze was 5% and the scratch resistance was excellent. When a paint film peeling test was conducted in the same manner as in Example 1, the adhesion was 100/100 and the adhesion was good.

<Example 5> (Coating of primer) A coating solution (I) for primer was applied to a polyvinyl chloride plate (manufactured by Takiron Co., Ltd.,
100 mm × 100 mm × 2 mm) using a # 8 bar coater, and dried at 20 ° C. for 30 minutes. (Overcoat coating) Overcoat coating and curing were carried out in the same manner as in Example 2 except that the above-mentioned primer-coated polyvinyl chloride plate was used.

When the total light transmittance and the haze were measured in the same manner as in Example 1, it showed good transparency of 87% and 0.7%. (Base material polyvinyl chloride plate thickness 2 mm) When this coating film was tested and evaluated for the degree of scratches in the same manner as in Example 1, the change in haze was 3% and the scratch resistance was excellent. When a paint film peeling test was conducted in the same manner as in Example 1, the adhesion was 100/100 and the adhesion was good.

Comparative Example 1 The polycarbonate coating was directly coated with the overcoat coating solution used in Example 2 without a primer. When the total light transmittance and the haze were measured in the same manner as in Example 2, the results were 91% and 0.5%.
And showed good transparency. (Base material polycarbonate plate thickness 2 mm) However, when this coating film was tested and evaluated in the same manner as in Example 1, the change in haze was 15% and partial peeling occurred. When a coating film peeling test was conducted in the same manner as in Example 1, the adhesiveness was 0/100 and the adhesion was poor.

Comparative Example 2 Coating of Primer A polycarbonate plate (100 mm × 100 mm × 2 mm) was coated in the same manner as in Example 1. (Coating of overcoat) A 100 ml four-necked flask equipped with a nitrogen introduction tube, a reflux condenser and a stirrer was used, and an acrylic resin (I
5 g of I) was added and dissolved at 65 ° C. MS-51
35 g was added. After adding 3.20 g of water to this solution, 3.33 g of 1N HCl was added, and the mixture was stirred at 65 ° C. for 30 minutes. This solution was coated on the above-mentioned primer-coated polycarbonate plate using a # 10 bar coater in the same manner as in Example 1, but the coating film became cloudy during coating and a good coating film was not obtained. <Comparative example 3>

(Coating of Primer) Polycarbonate plate (100 mm × 100 mm ×)
2 mm) was coated. (Coating of overcoat) A 100 ml four-necked flask equipped with a nitrogen introduction tube, a reflux condenser and a stirrer was used, and the acrylic resin (III) was added to 40 g of ethyl cellosolve.
5 g was added and dissolved at 65 ° C. Add MS-51 to this
5 g was added. After adding 3.20 g of water to this solution, 1
3.33 g of N HCl was added, and the mixture was stirred at 65 ° C. for 30 minutes. This solution was coated on the above-mentioned primer-coated polycarbonate plate using a # 10 bar coater in the same manner as in Example 1, but the coating film became cloudy during coating and a good coating film was not obtained.

<Comparative Example 4> (Coating of primer) A coating solution (II) for primer was applied to a polycarbonate plate (1 manufactured by Mitsubishi Kasei Co., Ltd.).
(00 mm × 100 mm × 2 mm) using a # 8 bar coater, and dried at 20 ° C. for 30 minutes. (Overcoat coating) Overcoat coating and curing were performed in the same manner as in Example 1 except that the above-mentioned primer-coated polycarbonate plate was used.

When the total light transmittance and haze were measured in the same manner as in Example 1, the transparency was 91% and 0.5%, which were excellent transparency. (Base polycarbonate plate thickness 2mm) However,
When this coating film was tested and evaluated for the degree of scratches in the same manner as in Example 1, the change in haze was 18% and partial peeling occurred. When a coating film peeling test was conducted in the same manner as in Example 1, the adhesiveness was 0/100 and the adhesion was poor.

[0047]

The hard coat of the present invention is excellent in scratch resistance, transparency, heat resistance, weather resistance and adhesion, and is
A good coating film can be formed on the surface of metals such as stainless steel, plastics, and wood.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C09D 133/06 PGC 7921-4J 183/06 PMU 8319-4J

Claims (3)

[Claims] 1. A hard coat obtained by applying a primer comprising the following coating composition onto a substrate, and then applying an overcoat comprising the following coating composition thereon. Primer: alkoxysilane (1), hydroxy (meth) acrylate copolymer (2) and organic solvent (3), and (1) / (2) is 1/0 or more and less than 1/3 (weight ratio) A coating composition obtained by adding a curing catalyst (4) to a certain mixture and hydrolyzing the mixture. Overcoat: Alkoxysilane (1), hydroxy (meth) acrylate copolymer (2) and organic solvent (3), and (1) / (2) is 1/3 or more 1 /
A coating composition obtained by adding a curing catalyst (4) to a mixture having a ratio of 20 or less (weight ratio) and hydrolyzing the mixture. 2. The hard coat according to claim 1, wherein the alkoxysilane (1) is a silicate oligomer represented by the following general formula (I). [Chemical 1] (N represents an integer of 1 to 20. R represents a true or branched alkyl group having 1 to 6 carbon atoms or an aryl group.) 3. A hydroxy (meth) acrylate copolymer (2) comprises at least 80 to 99% by weight of (a) a methacrylic acid ester component and an acrylic acid ester component.
And (b) at least one selected from a hydroxyacrylate component and a hydroxymethacrylate component in an amount of 1 to 20% by weight, the hard coat according to claim 1 or 2.