JPH0248081A - Method for finishing cement molded body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for decorating cement excipients, and more particularly to a method for obtaining a decorative layer of cement products with excellent weather resistance.

[Conventional technology]

Cement products have water absorption and water permeability, so it is inconvenient to use them as roofing materials or exterior wall panels without any surface treatment. Painting is common.

Conventionally, as a means of surface painting of such cement products, a colored cement slurry is applied to the surface of the shaped body immediately after shaping with a cement mixture, and then an emulsion resin is applied as an undercoat to prevent precipitation of Eflo components during curing. Generally, after preventing and curing this, a final coat is applied.

[Problems with conventional technology]

However, in the case of the above-mentioned coating method, even if an emulsion resin undercoat is applied, water vapor bones evaporate as the hardening reaction of the cement slurry layer accelerates during curing.
Countless micropores are formed in the emulsion paint layer, and on the other hand, the Eflo component that oozes out during the curing reaction of cement over time is eluted into water from rainfall, and as the water containing the Eflo component evaporates, the Eflo component forms an undercoat film. Remains between the top coat and
It had the disadvantage of reducing interlayer adhesion. In addition, deterioration is accelerated by infiltration of rainwater, oxidation by air, and ultraviolet rays from sunlight, resulting in cracking and chalking of the top coat.

[Problem to be solved by the invention]

In view of the above-mentioned drawbacks, this invention was made with the aim of suppressing the exudation of Eflo components from cement slurry as much as possible, and effectively preventing cracking and chalking of the top coat due to deterioration due to ultraviolet rays of sunlight. It is something.

(Technology for Solving the Problems) That is, in the method of decorating a cement extruded body of the present invention, a colored slurry is applied immediately after cement extrusion, an undercoat emulsion paint is applied, and an undercoat is applied in the step of applying a topcoat after curing. Pigment to resin ratio of 5 as emulsion paint
It is characterized by using an emulsion paint containing ~15%.

(Function) The process order of the method for decorating cement excipients in the present invention is the same as the conventional process.

In the present invention, the undercoat emulsion paint to be applied contains, unlike conventional emulsion paints, a filler containing pigment in an amount of 5 to 15% relative to the resin component.

This pigment preferably has a particle size distribution of 0.1 to 0.
If the undercoat emulsion paint is transparent, a pigment such as carbon white or alumina white that does not lose its transparency is used.

The reason for this pigment addition is the v! Increased I-density,
This is to suppress the oozing of the Eflo component from the cement excipient, and the reason why it is set at 5 to 15% with respect to the emulsion resin is that if it is less than 5%, the eflo oozing cannot be suppressed sufficiently.
This is because even if it is increased by more than 15%, it will only increase the cost and become uneconomical.

This pigment-added undercoat emulsion paint considerably suppresses the precipitation of the Eflo component from the cement excipient or the cement slurry layer, and as a result, the retention of the Eflo component at the interface with the top coat layer is suppressed. This also prevents cracks in the top coat.

〔Example〕

Next, the present invention will be explained in detail.

A colored slurry layer made by adding cement, a pigment, a water reducing agent, and water is applied to the surface of a cement excipient obtained by a conventional method of mixing cement, aggregate, reinforcing fibers, and water, and
Immediately after that, an undercoat emulsion paint consisting of an emulsion polymer of acrylic styrene and 10% carbon white pigment with a particle size distribution of 0.1 to 0.5μ is added for 50 to 50 minutes.
It is applied at a rate of 60 g/r+(), then cured, and then a top coat emulsion paint containing no pigment is applied at a rate of 50 to 60 g/r+.
It was applied at a rate of 0g/rrr.

After drying this, a test piece was obtained.

The obtained test piece was irradiated with ultraviolet rays for 16 hours and 60 hours in a dry state.
±3℃, UV source 230W/bo, 8 hours in wet condition 50
A weather resistance test was conducted by repeated irradiation under the conditions of ±3°C2 water sprinkling for 81/8 hours.

As a result, the decorative cement board obtained according to the present invention has a
There was no abnormality in the topcoat or undercoat film even after 0 hours had passed.
Only slight chalking occurred after 2000 hours, but chalking occurred after 1500 hours on the decorative cement board obtained by the conventional method, and obvious abnormalities were observed in the appearance.
After 000 hours, chalking occurred over the entire surface and the appearance became extremely poor.

〔effect〕

As explained above, this invention can effectively prevent the precipitation of Eflo components from cement excipients by simply adding a pigment to the undercoat emulsion paint, and as a result, the weather resistance of the surface decorative layer of cement products is significantly improved. It is.

Claims (1)

[Claims] (1) Immediately after forming the cement, apply a colored slurry, then apply an undercoat emulsion paint, and use an emulsion paint containing 5 to 15% pigment to resin as the undercoat emulsion paint in the process of applying a topcoat after curing. A method for applying makeup to a cement excipient.