JPH04339868A - Hard coating composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which forms a hard coating film excellent in hardness and flexibility by compounding a specific organosol of an inorg. substance, a binder consisting of an isocyanate compd. and/or a melamine compd., and a solvent. CONSTITUTION:The title compsn. is prepd. by compounding an organosol of an inorg. substance contg. at least one metal selected from the group consisting of these of the group III (B, Al, Ga, In, Tl. Sc, Y, La, and Ac), the group IV (Si, Ge, Sn, Pb, Ti, Zr, and Hg), and the group V (As, Sb, Bi, V, Nb, and Ta) in the long-form periodic table, at least one binder selected from the group consisting of an isocyanate compd. having at least two isocyanate groups and a melamine compd., and a solvent. The amt. compounded of the organosol is 30-75wt.% of the compsn. based on the solid content. The isocyanate compd. having no isocyanate group directly attached to an arom. ring is pref. to prevent the yellowing of a coating film.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard coat composition with excellent flexibility.

The hard coat composition of the present invention contains an inorganic substance (
It is useful as a paint or coating agent for the surfaces of steel plates, aluminum plates, glass, tiles, slate plates, etc.) and organic materials (wood, paper, cellophane, plastics, organic paint films, etc.). The steel plates targeted in the present invention include, for example,
Hot-rolled steel sheets, cold-rolled steel sheets, electrogalvanized steel sheets, hot-dip galvanized steel sheets, alloy-plated steel sheets, or chromic acid,
These include materials that have undergone chemical conversion treatment such as phosphoric acid, as well as tinplate, chin-free steel, stainless steel plates, etc. It is particularly useful in the field of home appliances, architecture and civil engineering (buildings, houses, curtain walls, tanks, plants, marine structures, bridges, etc.), and the field of transportation vehicles (automobiles, train cars, aircraft, etc.).

0003

BACKGROUND OF THE INVENTION As so-called hard coats having a pencil hardness of 6H or more, organopolysiloxane materials, polyfunctional acrylate materials, amino resin materials, etc. are used.

[0004] The use of organosilica sol is also being considered, and the isopropyl alcohol sol is added to melamine-alkyd resin (ceramics 20
(1985) No. 4, pp. 280-285) or using an organosilica sol obtained by hydrolysis of silicate esters with different hydrolyzability (Japanese Patent Publication No. 5
No. 2-17836), etc. are known.

[0005]

[Problems to be Solved by the Invention] Conventional hard coats generally have low flexibility and therefore are inferior in processability.

[0006] Furthermore, in the case of the two-component type, there is a problem that the pot life is relatively short.

[0007] Products using organosilica sol also have the problem that the pencil hardness is insufficient at 6H or less, and that flexibility decreases when trying to increase the hardness.

[0008]

[Means for solving the problem] The present inventors have developed an inorganic organosol (A), a binder (B), and a solvent (C).
By applying a coating composition containing the above to a substrate and then curing at room temperature or baking, the inorganic organosol and binder are uniformly dispersed through urethane bonds or ether bonds, improving hardness and flexibility. The present invention was completed based on the discovery that an excellent hard coat can be formed.

In the inorganic organosol (A) used in the present invention, the metal is a group III metal (B, Al, Ga, In, Tl, S
c, Y, La, Ac), IV group metals (Si, Ge, Sn
, Pb, Ti, Zr, Hf) and group V metals (As, Sb
, Bi, V, Nb, Ta) and mixtures thereof, preferably the metal is selected from Si, Al, Sn, Ti and Zr. It is a metal oxide sol.

The binder (B) is selected from isocyanate compounds having two or more functional groups, blocked isocyanate compounds, and melamine compounds. These alone,
Alternatively, two or more types can be mixed and added.

[0011] As the isocyanate compound, aliphatic,
Alicyclic, aromatic, and other polyisocyanate compounds and modified products thereof may be used. However, the weather resistance of the coating film,
In particular, in order to prevent yellowing, so-called non-yellowing polyisocyanate compounds that do not contain isocyanate groups directly bonded to aromatic nuclei are preferred. Non-yellowing polyisocyanate compounds include, for example, hexamethylene diisocyanate, 1,4-cyclohexane bis(methyl isocyanate), methylene bis(cyclohexyl isocyanate), cyclohexylmethane diisocyanate, isophorone diisocyanate, 2-isocyanate ethyl 2,6-diisocyanate hexanoate. ate, 2,6-diisocyanate methyl caproate, dimeryl diisocyanate, dianisidine diisocyanate, cyanuric acid, isocyanuric acid, and modified products thereof. Examples of modified products include trimer type, dimer type, prepolymer type, biuret type, urea type, and other modified types.In particular, trimer type, prepolymer type such as trimethylolpropane modified, biuret type, etc. Modified products are suitable. In some cases, aromatic yellowing polyisocyanate compounds may be used in place of or in addition to these non-yellowing polyisocyanate compounds.

[0012] In this specification, the term "blocked isocyanate compound" refers to a blocked isocyanate compound that can be deblocked under the following curing conditions to produce an isocyanate group, and can be produced by blocking the above polyisocyanate compound. Can be done. The blocking agent used for this blocking can be appropriately selected from various known blocking agents depending on the application and curing conditions. For example, lactam blocking agents such as ε-caprolactam, acetoxime, methyl ethyl ketoxime, methyl isoamyl ketoxime, methyl isobutyl ketoxime, other oxime blocking agents, phenol, cresol, catechol, nitrophenol, and other phenolic blocks. blocking agents, isopropanol, trimethylolpropane, other alcohol-based blocking agents, malonic acid esters,
Examples include, but are not limited to, acetoacetate and other active methylene blocking agents. Preferred blocking agents are, for example, lactam blocking agents and oxime blocking agents.

[0013] Generally, when the composition is used as a cold-curable hard coat composition, it is preferable to use a solvent that does not contain a hydroxyl group and an isocyanate compound that does not contain a blocking agent. When the composition is used as a baking-type hard coat composition and the solvent contains a solvent having a hydroxyl group such as water or alcohol, it is preferable to contain a blocked isocyanate compound. When a baking type is used and the solvent does not contain a hydroxyl group, an isocyanate compound or a blocked isocyanate compound may be used alone or as a mixture.

Examples of the melamine compound include dimethylolmelamine, trimethylolmelamine, tetramethylolmelamine, pentamethylolmelamine, hexamethylolmelamine, isobutyl ether type melamine, n-butyl ether type melamine, and butylated benzoguanamine.

The composition of the present invention preferably contains a catalyst for accelerating the reaction (D), since curing is accelerated and workability is improved.

As the catalyst (D), a basic or acidic curing catalyst can be used. Typical basic catalysts include dibutyltin dilaurate, dibutyltin diacetate, stannath octoate, other organotin compounds, methylimidazole, acridine, triethylamine, hexadecyltrimethylammonium stearate, and other amine catalysts. It is a compound. Typical examples of acidic catalysts include organic sulfonic acids such as methanesulfonic acid, dodecylbenzenesulfonic acid, and toluenesulfonic acid. As the catalyst (D), at least one of these basic catalysts and acidic catalysts is used, but a promoter or the like may also be used in combination. The proportion of the inorganic organosol (A) in the solid content of the paint is 30 to 75% by weight, preferably 40 to 70% by weight, based on the solid content. When the content of inorganic organosol exceeds 75%, the flexibility decreases, making it easy to peel off and making it difficult to form a coating, while below 30%, there is a surplus of low molecular weight binder, resulting in a decrease in hardness. At the same time, the flexibility also decreases.

[0017] As the solvent (C), a suitable amount of a solvent capable of dissolving each of the above ingredients may be used. In particular, organic solvents with high solubility in the inorganic organosol (A) are suitable, such as xylene, toluene, other aromatic hydrocarbon solvents, butyl acetate, other ester solvents, methyl isobutyl ketone, cyclohexanone, Examples include other ketone solvents, ethyl cellosolve, other glycol ether solvents, carbitol acetate, other diethylene glycol ester solvents, and various thinners. Of course, it is not limited to these, but may include other hydrocarbons, halogenated hydrocarbons, alcohols,
Phenolic, acetal, ester, ether, ketone, and other solvents may be used. However, when using an isocyanate as a binder for a hard coat composition that cures at room temperature, if a hydroxyl group-containing solvent such as alcohol or phenol is used as the solvent, the reaction between the binder and the solvent will result in a good coating film. difficult to obtain. Therefore, in this case, it is preferable to use a solvent that does not contain hydroxyl groups.

[0018] The above-mentioned solvent can be appropriately selected in consideration of the type and condition of the object to be coated, evaporation rate, working environment, and other conditions, but ketone solvents are particularly preferred since they provide a particularly good coating film.

The hard coat composition of the present invention contains the above-mentioned essential components (A), (B), and (C) and a catalyst (D).
Other components may be optionally added depending on the purpose. For example, in order to further improve the flexibility and weather resistance of the hard coat, a hydroxyl group-containing resin (fluororesin, acrylic polyol resin, polyester resin, urethane resin, etc.) can be added as necessary.

A pigment (E) can also be added if necessary.

Pigments (E) include yellow lead, molybdate orange, navy blue, cadmium pigments, titanium white, complex oxide pigments, inorganic pigments such as transparent iron oxide, cyclic high pigments, soluble azo pigments, and insoluble azo pigments. pigment, copper phthalocyanine pigment,
Examples include organic pigments such as dyeing pigments and pigment intermediates.

[0022] Colorants, thixotropic agents, fillers, thickeners, leveling agents, antifoaming agents, stabilizers and other additives can also be blended.

The hard coat composition of the present invention can be produced by mixing the above-mentioned components by a conventional method.

The hard coat composition of the present invention is applied onto a substrate by a known and commonly used method such as spray coating, brush coating, or roll coater, and left to cure at room temperature for about 1 to 10 days, or Cure by baking at 60-250°C for 1-30 minutes.

[0025]

[Examples] The present invention will be explained in more detail below with reference to Examples and Comparative Examples. However, these do not limit the present invention at all.

Examples and Comparative Examples A coating composition was prepared by mixing the following formulations in the composition shown in Table 1. The blending amount is expressed in parts by weight based on 100 parts by weight of organosilica sol dispersed in cyclohexanone. The substrate is a 0.4mm thick stainless steel plate (SUS3
04), the above coating composition was applied using a wire bar coater so that the dry film thickness was about 20μ, and the baking temperature was 1.
It was cured at 80°C for a baking time of 30 minutes. The physical properties of the resulting coating film were measured and the results are shown in Table 1.

■ Organosilica sol (A) non-volatile content: 3
0%, Solvent: Cyclohexanone ■ Blocked isocyanurate (B) Non-volatile content: 75%, Solvent: Ethyl acetate ■ Solvent (C) Cyclohexanone solvent

[0028]

[Table 1]

[0029] Paint film performance test method ■ Pencil hardness: Pencil hardness according to JIS K 5400 ■ Grid grid: Grid grid 1 mm width Cellotape peeling remaining number ■ Grid grid bending: Bending test machine φ2mm ○ Pass × Fail ■ Gloss: Specular gloss according to JIS K 5400 xylene: Xylene wiping test>200 indicates that the base was not exposed even after wiping 200 times.

[0030]

Effects of the Invention The hard coat obtained from the hard coat composition of the present invention has an excellent surface hardness (pencil hardness of 6H or more) equivalent to or higher than that of conventional hard coats, and has an inorganic organosol and a binder. Because it is uniformly dispersed through newly formed bonds, it has excellent flexibility and is suitable for use in the architectural and civil engineering fields such as curtain walls, sashes, plants, and marine structures, as well as automobiles and train cars. It can be used in the transportation vehicle field, etc.

Claims (5)

[Claims] [Claim 1] Metal is a long-period element in the periodic table.
Group III (B, Al, Ga, In, Tl, Sc, Y, L
a, Ac), IV group metals (Si, Ge, Sn, Pb, T
i, Zr, Hf) and group V metals (As, Sb, Bi, V
, Nb, Ta) and one or more inorganic organosols (A) selected from mixtures thereof, isocyanate compounds having two or more functional groups, and melamine compounds. binder (B) and solvent (C), and the blending ratio of inorganic organosol (A) in the solid content (based on solid content) is 30 to
75% by weight of a hard coat composition. 2. The composition further comprises a catalyst for promoting reaction (D).
The composition according to claim 1, comprising: [Claim 3] As an inorganic organosol (A),
3. The composition according to claim 1, wherein a metal oxide sol is used in which the metal is selected from Si, Al, Sn, Ti and Zr. Claim 4: Inorganic organosol (A
) The composition according to any one of claims 1 to 3, wherein the blending ratio (solid content basis) of the composition is 40 to 70% by weight. 5. The composition according to claim 1, further comprising a pigment (E).