JPH028273A - Silicon alkoxide-based coating material - Google Patents

Abstract

PURPOSE:To obtain the subject coating material, capable of forming films, having a high hardness and excellent in weather resistance without causing cracking, peeling, etc., even in substrates having a relatively large dimensional change for a long period by using colloidal silicas having different particle diameters in combination as a filler. CONSTITUTION:The objective coating material formed by using silicas, containing colloidal silica in an amount of 2-12wt.% expressed in terms of solid content dispersed in water and/or an organic solvent as a filler and two or more of the silicas having different particle diameters in combination, hydrolyzing and polycondending monomers consisting essentially of silicon alkoxides. Two or more thereof are kept at average particle diameter ratio of 1.6/1 (average particle diameter of the silica particles having a larger particle diameter)/(average particle diameter of the silica particles having a smaller particle diameter).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to silicon alkoxide coating materials.

[Conventional technology]

Silicon alkoxide coating materials have excellent weather resistance and form a highly hard coating film, so they can be applied to the surface of substrates made of plastic, wood, cement, etc., which have the disadvantage of being chemically weak. It is widely used to protect these base materials, and is particularly known as a hard coating material for plastics.

Research and development regarding this coating material can be found in, for example, JP-A-49-14535 and JP-A-50-116600.
As seen in the above publications, it has been actively promoted for some time, and demands for improvement of the physical properties of the coating film are also increasing.

[Problem to be solved by the invention]

However, when such silicon alkoxide-based coating materials are applied to base materials that undergo relatively large dimensional changes, such as cement-based building materials, there is a problem in that the coating film is likely to crack or peel. In order to overcome this point, there is a method of including a large amount of a dialkyldialkoxysilane component, but this causes another problem in that the hardness of the coating film decreases significantly.

In view of the above circumstances, the present invention has been developed to ensure that even when painted on base materials with relatively large dimensional changes such as cement-based building materials and wood, they will not develop cracks over a long period of time, and will also have high hardness and weather resistance. An object of the present invention is to provide a silicon alkoxide coating material that can form an excellent coating film.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a silicon alkoxide-based coating material obtained by hydrolysis and polycondensation of a monomer containing silicon alkoxide as a main component, which is dispersed in water and/or an organic solvent as a filler. Contains colloidal silica in a solid content of 2 to 12% by weight,
In addition, two or more types of colloidal silica with different particle sizes are used in combination, and any two of them are used in combination.
In both cases, the average particle size ratio of the seeds is: average particle size of larger silica particles/average particle size of smaller silica particles = 1.6
/ Make sure it is kept at 1 or higher.

[For production]

In the silicon alkoxide coating material of this invention,
Since a combination of colloidal silica with different particle sizes is used as a filler, the packing of silica particles as a reactive filler approaches close-packing, and as a result, the vehicle hardens while shrinking during curing. The impact can be reduced. That is, it is possible to form a stable coating film that does not cause cracks, peeling, etc. even on a substrate with relatively large dimensional changes. At that time, for any two types of the same silica particles, the average particle size of the larger silica particle/the average particle size of the smaller silica particle is 1.6
/ If it is less than 1, the above-mentioned effects of the present invention cannot be sufficiently obtained. In addition, if the content of colloidal silica in the coating material is less than 2% by weight in terms of solid content, it may not be possible to obtain a sufficient film thickness when used as a clear coating, and the smoothness of the coating may be affected. It also becomes inferior. On the other hand, if the solid content exceeds 15% by weight, the coating film will become too hard, causing cracking and peeling.

〔Example〕

The present invention will be explained in detail below.

The silicon alkoxide which is the heptamer component of the silicon alkoxide coating material in this invention has the general formula R
, Si (OR')4-0 [wherein R and R' are alkyl groups having 1 to 4 carbon atoms, and n is 01 or 2], for example, in the above formula, n= Examples of n=0 include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, etc., n-1 include methyltrimethoxysilane, methyltriethoxysilane, etc., and n=2 include dimethyldimethoxysilane. Moreover, a part of the above R may be an epoxy group, an amino group, or the like.

This 7-mer component has the following compounding ratio;
(OR') Silicon alkoxide 0-1 composed of 4
00 parts by weight (a) 100 parts by weight of silicon alkoxide formed by the general formula R3i (OR') 15 to 50 parts by weight of silicon alkoxide formed by the general formula Rt S t (OR') It is preferable, but not limited to this.

Catalysts added for the hydrolytic double condensation of the above monomers include dilute solutions of inorganic acids such as hydrochloric acid, phosphoric acid, and sulfuric acid, and organic acids such as formic acid, acetic acid, oxalic acid, and chloroacetic acid. Examples include acidic catalysts, quaternary ammonium salts or amine salts of the above-mentioned inorganic and organic acids, organometallic compounds such as organic tin compounds, and metal salts with organic acids, but are not limited to these. The above-mentioned amines include trimethylamine, triethylamine n-butylamine, etc., and the above-mentioned organometallic compounds or metal salts with organic acids include dibutyltin dilaurate diacetate or diacetate, tin octylate, zirconocene dichloride, titanocene dichloride, and lead naphthenate. etc. can be exemplified. These catalysts may be used alone or in combination, and are blended within an appropriately set amount.

As the curing agent, water or the like can be used, and if necessary, a curing accelerator may be added. The amount added is not particularly limited, and the amount necessary for smooth curing (hydrolysis and polycondensation) can be set as appropriate.

Furthermore, when carrying out hydrolytic monopolycondensation, it is preferable to use various diluting solvents. Examples of this solvent include lower alcohols such as methanol, ethanol, propatool, and isopropyl alcohol (IPA), diols such as ethylene glycol, and cellosolves such as ethylene glycol monomethyl ether. Or multiple types are used together.

Next, colloidal silica will be explained.

First, this filler may be added before or after the hydrolytic 9-polycondensation of the monomers,
The timing of addition is not particularly limited. No matter which stage the filler is added to, it is recommended that the filler be sufficiently dispersed and mixed using a dispersion machine such as a dispersion machine.

The particle size of the silica particles is as described above, and for example, when using three types of silica particles A, B, and C with different particle sizes (average particle size A>B>C), A/B2
! :1.6/1. It is necessary that B/c≧1.6/1. Moreover, it is preferable that the particle diameter of the large and small silica particles is within the range of about 5 to 1100 nm. If it is too large, the smoothness of the coating film tends to deteriorate, and if it is too small, it may not be effective as a filler. Further, the amount of these silica particles added is not particularly limited, but it is preferable that the larger silica particles are contained in an equal or more weight amount than the smaller silica particles.

The organic solvent for dispersing the silica particles is not particularly limited, but it is preferable to use alcohols, cellosolves, etc., for example. Water and these organic solvents are
Either one can be used alone or multiple types can be used in combination. Note that commercially available colloidal silica dispersed in such a solvent can also be used.

The silicon alkoxide-based coating material prepared as described above is prepared as a siloxane prepolymer solution (liquid A) having an alkoxide group at the end, and at the time of use, a curing agent, etc. is further added to this liquid A to form the final product. It can be made to harden. In this way, the product may be stored in two packages, but it is also possible to use a single package in which all the ingredients are mixed in advance and stored in one container. In the case of a two-pack type, the curing agent and catalyst added at the time of use can be the same as those added at the monomer stage, and the same diluent solvent as above may also be added.

The coating method is spray painting.

Roll coating, flow coater coating, dipping coating, etc. are not particularly limited. Further, the conditions for drying and baking after painting are not particularly limited, but it is preferably carried out at about 50 to 200°C.

In addition, the silicon alkoxide coating material according to the present invention may further contain various ordinary colorants, as required.
Fillers other than the colloidal silica (alumina sol, fumed silica, etc.), surfactants, thickeners, ultraviolet absorbers, etc. may be added as appropriate.

Next, more detailed examples of the present invention will be described together with comparative examples.

Examples 1 to 5. Comparative Examples 1 to 4 - Methyltrimethoxysilane as the silicon alkoxide of Co.
Tetraethoxysilane and methyltrimethoxysilane, IN hydrochloric acid as a catalyst, water as a curing agent, IPA as a diluting solvent, IPA organosilica sol as a colloidal silica filler [Catalyst Chemical Industry side layer 0SCAL 1436
(Average particle size φ72 nm).

Same 1454 (φ25nm), Same 1432 (φ12n
m), 1431 (8 nm); 5iOz content 30%, the above 1436 and 1431 are prototypes], the respective components were mixed in the amounts shown in Table 1, and the mixture was heated at 25°C.
The mixture was stirred for 30 minutes at 500 rpm.

The resulting two-pack type coating material A solution was stored in a sealed state at 25°C for one week, and at the time of use, water and IPA were added in the amounts shown in Table 1 for 100 parts by weight of the same A solution. and stirring at 500 rpm for 10 minutes at 25°C.

■ Kamiahihiki flag: An inorganic hardened body obtained by paper-making and press-forming a raw material slurry mainly consisting of blast furnace slag, Portland cement, silica sand, pulp, asbestos, and vinylon fiber as a bond base material, and then steam-curing. It was used. The bulk density of this base material is 1.8 g/cut, and the dimensional change from saturated water absorption to absolute dry state (after drying at 105°C for 24 hours) is 0.3.
It was 0%.

A primer layer with a film thickness of 10 μm was previously formed on the above base material using a urethane-modified silicone primer (manufactured by Toshiba Silicone Co., Ltd.), and the above coating material was spray-painted on top of this at 150°C for 1 hour. Burnt.

For each coating film obtained (all film thickness 10n), 60
A cycle test was conducted under the conditions of immersion in warm water at 10°C for 8 hours and drying at 60°C for 16 hours, and the properties of the coating film after 10 or 30 cycles were observed.

Furthermore, for a coating film similarly formed on an alumina substrate (no primer layer), the JIS standard number is -5400.
Pencil hardness was measured according to .

The above results are also shown in Table 1.

As shown in Table 1, the coating materials of Examples were able to sufficiently respond to dimensional changes in the substrate and provide a highly hard coating film. On the other hand, in Comparative Example 1, the particle size of colloidal silica is single, in Comparative Example 2, the particle size ratio of large particles to small particles is less than 1°6/1, and in Comparative Example 3, the colloidal silica content is 2% by weight. % (solid content), whereas in Comparative Example 4, the same content exceeded 12% by weight,
The resulting coating films are all prone to cracking.

〔Effect of the invention〕

The silicon alkoxide coating material according to the present invention does not cause cracks or peeling over a long period of time, even on base materials with relatively large dimensional changes such as cement building materials, and has high hardness and excellent weather resistance. Enables the formation of a coating film.

1986

Claims (1)

[Claims] 1 A silicon alkoxide-based coating material obtained by hydrolysis and polycondensation of a monomer containing silicon alkoxide as a main component, in which colloidal silica dispersed in water and/or an organic solvent as a filler has a solid content of 2 to 2.
12% by weight of colloidal silica, and two or more types of colloidal silica with different particle sizes are used in combination, and the average particle size ratio of any two of them is the larger silica particle. A silicon alkoxide coating material characterized in that the average particle diameter of the smaller silica particles is maintained at a ratio of 1.6/1 or more.