JP2003055581A - Inorganic coating material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an inorganic coating material affording a scarcely fouling film with suppressed occurrence of microcracks, or the like, and excellent weather resistance. SOLUTION: This inorganic coating material comprises colloidal silica and sepiolite in an amount of 5-200 pts.wt. based on 10 pts.wt. of the colloidal silica as principal components. The colloidal silica is used for imparting hydrophilicity to the inorganic coating material. The occurrence of the cracks of the resultant film is suppressed by compounding the colloidal silica with the sepiolite.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inorganic coating material which is an inorganic coating material.

[0002]

2. Description of the Related Art For outer walls of houses and concrete structures,
Paint is applied for the purpose of protecting the base material and improving the design. In recent years, the use of acrylic silicone paints and fluororesin paints, which have excellent weather resistance in terms of durability, has been increasing. Further, there is a demand for a paint that is less likely to get dirty due to its durability, and for that reason, as for dirt, a coating film having a hydrophilic property so that the dirt can be washed away with rainwater is mainly used. Among them, inorganic coatings have been attracting attention as a material having both weather resistance and stain resistance. However, the inorganic coating material has a drawback that cracks easily occur, and prevention of such cracks is an issue.

For example, Japanese Patent Application Laid-Open No. 1-163275 discloses an invention in which a needle-like inorganic substance is added to alkoxysilane as a filler to prevent cracks.
Japanese Patent Publication No. 27424/1996 discloses an invention in which alkali titanate is added to colloidal silica to prevent cracks. However, alkoxysilane has a drawback that a large amount of alcohol is generated during curing, which is environmentally unfavorable, and alkali titanate exhibits an oxidative action due to ultraviolet rays, thereby oxidatively degrading an organic component.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an inorganic coating composition that does not adversely affect the environment, has excellent weather resistance in which the occurrence of microcracks and the like is suppressed, and is resistant to stains.

[0005]

Means for Solving the Problems The present inventor has studied a large number of inorganic materials in order to suppress cracks in inorganic coating materials and has found that sepiolite is superior to colloidal silica. The present invention is based on this finding.
That is, the inorganic coating material of the present invention is characterized by mainly containing colloidal silica and 5 to 200 parts by weight of sepiolite with respect to 100 parts by weight of the colloidal silica. In the inorganic coating material of the present invention, colloidal silica is used to impart hydrophilicity. The colloidal silica is mixed with sepiolite, which is an acicular inorganic substance, to prevent cracking of the coating film obtained.

Examples of the colloidal silica include an aqueous silica sol in which high-molecular-weight silicic acid fine particles are dispersed in water, or an organosilica sol in which a solvent such as methyl alcohol or isopropyl alcohol is dispersed. From the viewpoint of workability and economy, it is preferable to use an aqueous silica sol.

As a sepiolite, the longest needle-like distance /
A large aspect ratio, which is a ratio of thickness (diameter), is preferable. It is preferable to use a material having an aspect ratio of substantially 10 to 100.

The particle size of colloidal silica is usually 2 to
It is about 100 nm. Sepio Ray is 50μ in length
m or less, preferably 30 μm or less. If a large one is used, it will also protrude from the obtained coating film, and the appearance and coating characteristics of the coating film will deteriorate.

The mixing ratio of sepiolite is 5 to 200 parts by weight, more preferably 25 to 75 parts by weight, based on 100 parts by weight of colloidal silica. When the blending ratio of sepiolite is relatively increased, the crack resistance of the coating film is improved,
Properties such as hydrophilicity deteriorate.

The colloidal silica itself has a function as a binder, but it is preferable to use a binder in order to enhance the film forming property of the coating film and further prevent the coating film from cracking. As a binder, metal alkoxide, water glass,
A resin emulsion can be used.

Examples of the metal alkoxide include alkoxysilane. Alkoxysilanes are preferred from the viewpoints of flexibility and performance such as heat resistance and price.

The mixing ratio of the metal alkoxide is 10 to 1 based on 100 parts by weight of colloidal silica in terms of solid content.
00 parts by weight, preferably 20 to 50 parts by weight. When the compounding ratio of the metal alkoxide is less than 10 parts by weight, the resulting coating film is less likely to follow expansion and contraction due to changes in the temperature and humidity of the adherend, so that hair cracks and the like are likely to occur. Is also unfavorable because the affinity of is also reduced. On the other hand, if the amount of metal alkoxide is too large, the film hardness, fire resistance and heat resistance will decrease, which is not preferable.

As the resin emulsion, known ones such as acrylic resin emulsion, silicone resin emulsion and fluororesin emulsion can be used. The resin emulsion is superior in film forming property to alkoxysilane and water glass, but is inferior in fire resistance and heat resistance. The mixing ratio of the water glass and the resin emulsion to the colloidal silica may be about the same as the alkoxysilane in terms of solid content.

As other components, a pigment such as an extender pigment, a thickener, a defoaming agent, and a surface conditioner can be blended.

Examples of the inorganic pigments include titanium white, titanium yellow, red iron oxide, chromium oxide green, ultramarine blue,
Examples thereof include graphite.

These other components are colloidal silica 10
About 40 parts by weight can be mixed with 0 part by weight.

In producing the inorganic coating material of the present invention, it can be produced according to a conventional method for producing an aqueous coating material. As a coating method, it is preferable to coat the solution as it is, or to add a dispersion medium such as water, if necessary, with an aqueous brush, a roll brush, an air sprayer, an airless sprayer or the like to a coating film thickness of 20 to 50 μm. After coating, the inorganic coating material of the present invention can be air-dried at room temperature or heated and forcedly dried with hot air.

A method for preparing a coating material using an alkoxysilane as a binder, which is a typical inorganic coating material of the present invention, will be described in a little more detail.

The alkoxysilane has a general formula of Rn
Si (OR ′) 4 n [wherein R is a methyl group, an ethyl group, or a propyl group, R ′ is an alkyl group having 1 to 4 carbon atoms, and n is 0.1 or 2]. Can be used. For example, in the above equation, n = 0
Examples thereof include tetramethoxysilane, tetrapropoxysilane and the like, examples of n = 1 include methyltrimethoxysilane and methyltriethoxysilane, and examples of n = 2 include dimethyldimethoxysilane and the like. Further, the R may be an epoxy group, an amino group or the like.

A catalyst may be added for the hydrolysis and polycondensation of the alkoxysilane. Examples of the catalyst include acidic catalysts represented by dilute solutions of inorganic acids such as hydrochloric acid and phosphoric acid and organic acids such as formic acid and acetic acid, quaternary ammonia salts or amine salts of these inorganic and organic acids, and organic tin compounds. Examples thereof include organic metal compounds such as and metal salts with organic acids.

Water or the like can be used as a curing agent, and if necessary, a curing accelerator may be added. The blending amount thereof is not particularly limited, and it is preferable that an amount necessary for curing (hydrolysis and polycondensation) to proceed smoothly is appropriately added. For example, the blending amount of water with respect to the silicon alkoxide is 1% by weight to 12
It is appropriate to set it to about wt%.

The coating composition comprising the above-mentioned alkoxysilane, catalyst, curing agent, colloidal silica and flaky inorganic material is preferably prepared in a solution having an appropriate concentration with a diluting solvent. Examples of the diluting solvent include lower alcohols such as methanol, ethanol, propanol and isopropyl alcohol (IPA), ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and butyl acetate, diols such as ethylene glycol and ethylene. Examples thereof include cellosolves such as gucol monotyl ether, and these can be used alone or in combination of two or more kinds.

In order to uniformly disperse the colloidal silica and the scaly inorganic material in the coating composition-containing solution, it is preferable to use a disperser such as a disper.

The inorganic coating material obtained is not particularly limited and may be spray coating, roll coating, flow coater coating, dip coating or the like. Also, the drying and baking conditions after coating are not particularly limited, but it is preferable to carry out at 10 to 200 ° C, and if the temperature is lower than 10 ° C, the coating film is hard to cure.
If the temperature exceeds 00 ° C, the coating film tends to crack easily.

By using the inorganic coating material of the present invention, it can be used as a construction industrial material in the field of construction or plant such as an inorganic fiber board, a fireproof coating material, a cement board, a calcium silicate board, a gypsum slag cement board, a brick and a steel sheet. On the adherend,
Heat resistance, weather resistance, fire resistance, rust resistance, and designability can be imparted, and high durability and maintenance-free can be realized.

[0026]

Since the inorganic coating material of the present invention contains colloidal silica as a main component, the resulting coating film has hydrophilicity and does not adhere strongly to oil components. Washed away.

Further, sepiolite is blended. Sepiolite mechanically connects colloidal silica particles to each other, and imparts durability such as crack resistance to the resulting coating film. The coating film obtained by blending a binder in addition to colloidal silica and sepiolite is significantly strengthened, and the coating film forming ability is also enhanced.

A typical inorganic coating material of the present invention, which uses colloidal silica, sepiolite, and alkoxysilane as a binder, will be described. By adding sepiolite, a filling effect and a reinforcing effect due to the needle-like shape are obtained, and shrinkage during drying is reduced, and as a result, cracking is reduced. Further, the alkoxysilane reacts with the colloidal silica to increase the binding force between the colloidal silica particles and to suppress the cracks by the filling effect by filling the space between the colloidal silica particles.

By using colloidal silica, sepiolite and alkoxysilane in combination as described above, cracking of the coating film obtained can be prevented. Further, since the colloidal silica itself has hydrophilicity, it does not adhere to the stain component (mostly oily) to the coating film and can be easily washed off with rainwater.

[0030]

[Examples] Test examples will be described below.

Table 1 shows the composition and evaluation. 1 to No. Four kinds of inorganic paints of No. 4 were prepared, and the obtained coating films were evaluated. In this test example, an acrylic resin emulsion was used as the binder. As the colloidal silica used in this test, Silica Doll 50 (Nippon Kagaku Kogyo) was used. Satinton Special (Sobueclay) was used as kaolin. Toda color KNO (Toda Kogyo) was used as the bento.

The sepiolite, wollastonite, basic magnesium sulfate and tetrapot zinc oxide used in this test have the shapes shown in Table 2.

[0033]

[Table 1]

[0034]

[Table 2]

In order to prepare the inorganic coating material, first, colloidal silica, kaolin, rouge, dispersant, sepiolite, wollastonite, one of basic magnesium sulfate and tetrapot type zinc oxide, and an acrylic emulsion are used. The resulting mixture was mixed with water as a dispersion medium, and then sufficiently dispersed and stirred with a dispenser using water as a dispersion medium. Then, using these four types of inorganic coating materials obtained, the film forming properties of the coating film and the presence or absence of cracks in the formed coating film were first examined. As the adherend, a commercially available siding board coated with a primer (urethane emulsion type) by air spray and then dried at 80 ° C. for 3 minutes was used. Then, the No. 1 to No. Four kinds of inorganic coatings of No. 4 were applied by air spray, dried at 80 ° C. for 3 minutes, and then cured at room temperature for 1 week.

Using each test body thus obtained,
First, the film forming property and the presence or absence of cracks were visually examined. The results are also shown in Table 1. The symbol ◯ of the appearance in Table 1 indicates a coating film in which a film was formed and no cracks occurred. A mark indicates that a film was formed but cracks occurred, a mark indicates that a film was not formed, and a mark indicates that a film could not be applied.

The stability shown in Table 1 means the stability as an inorganic paint, and No. The inorganic paint of No. 3 gelled and had no stability as a paint. Safety means the safety of the composition, and all inorganic paints were judged to be safe.

The weather resistance is the result of the accelerated weather resistance test, and N
o. The weather resistance of the inorganic coating material No. 1 was good. N
o. 2 to No. No accelerated weathering test was performed on the inorganic coating material of No. 4. In addition, No. For the inorganic paint of No. 1, see JI
The alkali resistance test and the acid resistance test were performed by the method described in SK5400, the water resistance test in which the sample was immersed in water at 20 ° C. for 1 month, and the freeze resistance test was performed by the method described in JIS A5422. No abnormality was found in the coating film in any of the alkali resistance test, acid resistance test, water resistance test and freeze resistance test.

Of the tested high aspect ratio inorganics, it was sepiolite that was effective in crack resistance. Wollastonite has no problem in shape but has no effect because it is easily broken, and it is considered that the shape of tetratpot-type zinc oxide was not suitable. Furthermore, basic magnesium sulfate reacts with colloidal silica as a binder to form a gel, which is problematic in stability.

As a result, sepiolite was preferable as an inorganic substance of the inorganic coating material without any problems in all aspects.

Further, sepiolite is a naturally occurring fibrous mineral, and the entanglement of these fibers can suppress the volume shrinkage during drying. Further, since the material itself has a water retention property, the drying progresses slowly, resulting in internal stress. Is moderated. The shape and water retention effectively suppress the occurrence of cracks. Further, since the amount of eluted ions is small and it does not affect other materials, the stability is good. Furthermore, since sepiolite requires a small amount to be added, it has an effect of producing a low-cost inorganic coating material.

Sepiolite showed excellent crack resistance even in the case of an inorganic paint using water glass and colloidal silica instead of the acrylic resin emulsion used as the binder.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsushi Mase             Okawagahara, Iino, Fujioka-cho, Nishikamo-gun, Aichi             1141 Address 1 Aisin Kako Co., Ltd. (72) Inventor Toshio Teramoto             Okawagahara, Iino, Fujioka-cho, Nishikamo-gun, Aichi             1141 Address 1 Aisin Kako Co., Ltd. F-term (reference) 4J038 AA011 CG141 DL021 DL031                       HA441 HA446 HA451 HA456                       KA04 KA06 KA19 MA08 MA10                       NA01 NA03 NA05 NA06 NA11                       NA14 NA27 PC02 PC03 PC04

Claims (3)

[Claims] 1. An inorganic coating material comprising, as main components, colloidal silica and 5 to 200 parts by weight of sepiolite with respect to 100 parts by weight of the colloidal silica. 2. The inorganic coating composition according to claim 1, which contains 10 to 100 parts by weight of a binder based on 100 parts by weight of the colloidal silica. 3. The binder is alkoxysilane,
The inorganic coating material according to claim 2, which is one of water glass and a resin emulsion.