JP2001207652A - Method of repairing exterior-wall coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of repairing exterior-wall coating, by which a firm foundation layer and a topcoating layer can be formed even when an old film remains. SOLUTION: A repair agent, which contains a polyisocyanate compound and an organic solvent and has a 5-70 mass % nonvolatile content, is rubbed on an old topcoating layer requiring repair by a roller, the foundation layer is formed by curing the old film after the remelting of the old film, and the topcoating layer is formed onto the foundation layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for repairing a building outer wall.

[0002]

2. Description of the Related Art An outer wall of a building is damaged or peeled off for various reasons, so that it has to be repaired. The main ones are:
Peeling due to poor adhesion to the undercoat layer, cracking due to aging of the top coat layer, blistering due to water circulation, blistering due to solar heat, cracking due to stress, and the like.

Conventionally, the outer wall to be repaired for the above-mentioned various reasons has conventionally been obtained by sufficiently peeling off the top coat layer and the base layer with kerosene, exposing the base material coated with the sealer, and then again applying the primer layer with the primer. It was common to form and then form a topcoat layer.

[0004]

As described above, the conventional method of repairing an outer wall requires a great deal of time to remove the old paint film by using kerane. An object of the present invention is to provide a method for repairing an outer wall coating capable of forming a strong underlayer and a topcoat layer even when an old coating film remains.

[0005]

According to the present invention, there is provided a method for repairing an exterior wall coating, wherein a polyisocyanate compound and an organic solvent are contained on an old top coat layer requiring repair, and the nonvolatile content is 5 to 70% by mass. The repair agent is rubbed with a roller, the old coating film is redissolved, and then cured to form an underlayer, and a topcoat layer is formed on the underlayer.

[0006] The above-mentioned rubbing step of the repairing agent is performed twice, the non-volatile content (NVa) of the repairing agent (a) used in the first rubbing step is 5 to 50% by mass, and the repairing agent (b) used in the subsequent rubbing step is used. )), The nonvolatile content (NVb) may be 10 to 70% by mass, and NVa ≦ Nb. Also,
The polyisocyanate compound may be a burette type isocyanate prepolymer.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

[0008] The repair method of the present invention is applied to a multi-layer hard coating, a multi-layer elastic coating, a waterproof multi-layer coating, a thick coating, a mastic coating as long as it has a layer containing a synthetic resin. It can be used for any type of outer wall, such as a moisture-permeable coating.

The outer wall has, for example, the following configuration. That is, the sealer layer, the base layer, and the elastic or inelastic top coat layer, the sealer layer fills holes and steps on the outer wall surface, sucks the base layer, and prevents alkali leaching from the outer wall surface, and It prevents the neutralization of the outer wall. Examples of the resin used for the sealer include a solvent type or an aqueous emulsion such as an acrylic resin, an epoxy resin, and a urethane resin, and an aqueous emulsion of an acrylic resin is most commonly used.

The base layer (and, if necessary, the pattern layer) is formed of an intermediate coating, and is required to have some degree of elasticity and moisture permeability. Examples of the resin used for the intermediate coating material include an aqueous emulsion of an acrylic resin, a solvent-type epoxy resin, an aqueous emulsion-type epoxy resin, and a solvent-type urethane resin.
Aqueous emulsions of acrylic resins, as well as sealers, are most commonly used.

On the other hand, the elastic or inelastic top coat layer is a layer which is required to have crack followability, weather resistance, light resistance, water resistance, stain resistance, etc., and is a solvent type or aqueous emulsion of the acrylic resin or urethane resin. In addition, solvent-based and aqueous emulsions of fluorine resin or silicone resin are used.

[0012] The coating material for forming the sealer layer, the base layer, the pattern layer and the top coat layer contains various additives. Examples of additives include organic and inorganic coloring pigments and extenders, aggregates such as silica sand and shirasu balloons, and others, defoamers, plasticizers, rust inhibitors, preservatives, plasticizers, dispersants, solvents, In the case of an aqueous emulsion, a deicing agent or PH
Modifiers are included.

In order to repair the outer wall having the above structure,
First, the above-mentioned repair agent is rubbed with a roller on the coating film of the top coat layer. Then, the top coat film that could not be removed (or was not removed) is dissolved in the organic solvent in the repair agent.

In the repair method of the present invention, the water contained in the old top coat film dissolved in the organic solvent and the active hydrogen such as hydroxyl group and carboxyl group present in the resin constituting the film are formed by: It is presumed to react with the polyisocyanate compound in the repair agent. In addition, the repair agent penetrates into the old top coat layer remaining without being dissolved and the underlying layer adjacent to this layer, and the water contained in each layer and the active hydrogen group-containing resin also react with the polyisocyanate compound. I think that the. As a result, it is presumed that a high tensile strength serving as an underlayer of the new top coat layer is high, and a uniform underlayer without cracks can be formed.

The repair agent used in the present invention is a urethane resin solution containing 5 to 70% by mass, preferably 10 to 60% by mass of a nonvolatile component. Examples of usable polyisocyanate compounds include aliphatic polyisocyanate compounds such as hexane diisocyanate and trimethylhexamethylene diisocyanate, and aromatics such as 4,4'-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI) and hydrogenated MDI. And alicyclic polyisocyanate compounds such as isophorone diisocyanate, hydrogenated xylylene diisocyanate, and cyclohexylmethane diisocyanate. Further, in the present invention, a buret type isocyanate prepolymer obtained by reacting each of the above polyisocyanate compounds with water or a tertiary alcohol such as t-butanol is also preferably used because it has good reactivity and can shorten a recoating interval. Can be

Organic solvents suitable as a thinner for the above-mentioned polyisocyanate compound and isocyanate prepolymer include hydrocarbons such as toluene and xylene, ethyl acetate, and the like.
Esters such as n-butyl acetate, methyl ethyl ketone,
Ketones such as methyl isobutyl ketone; Also,
In order to control the viscosity of the repair agent, a thixotropic agent such as hydrophobic silica and aliphatic polyamide wax can be used in combination. In the repair method of the present invention, a catalyst for curing the polyisocyanate compound is not particularly required. Even without a catalyst,
The polyisocyanate compound reacts sufficiently as described above to form an underlayer having high tensile strength.

The rubbing application with the above-mentioned repair agent depends on the condition of the old coating film, but it is often better to carry out the application in two parts. When applying twice, first dissolve the old coating with a repair agent with a high organic solvent content, and then
It is treated with a repair agent having a large content of a polyisocyanate compound, that is, NVa ≦ NVb. As the repairing agent a to be used first, the nonvolatile content NVa is 5 to 50% by mass,
Further, the content is preferably 10 to 30% by mass. In this range, the old top coat layer can be efficiently dissolved and reacted with the polyisocyanate compound so that the dissolved matter does not flow down. Further, as the repairing agent b to be used next, the nonvolatile content NVb is 10 to 70% by mass,
0-60 mass% is preferable. Within this range, it is possible to achieve smoothing by re-dissolving the melt and formation of an underlayer having high tensile strength.

After the repair agent is rubbed and applied, a new top coat layer is applied after the repair surface is dried. The paint for the top coat layer used for repainting is not particularly limited, for example, a solvent type urethane paint, a solvent type silicone paint,
Aqueous acrylic emulsion paints and aqueous urethane emulsion paints can be mentioned. When the construction site is in a warm region, any of the above paints can be suitably used. However, in a cold region, it is preferable to use a solvent type urethane resin, a solvent type silicon paint or the like.

On the underlayer formed by the repair agent, a cement-based or synthetic resin-emulsion-based finish adjusting material for finish coating is applied for the purpose of imparting a design property. It is also preferable to form a coat layer.

[0020]

Next, the present invention will be described more specifically with reference to examples and comparative examples.

Example 1 Preparation of repair agent 4,4'-diphenylmethane diisocyanate (MDI) was used as a polyisocyanate compound component, and a 1: 1 (mass ratio) mixture of xylene and toluene was used as an organic solvent component. After adjusting to 10% by mass, Repair Agent 1 was prepared.

Further, a repairing agent 2 was prepared by using MDI as the polyisocyanate compound component and a 1: 1 mixture of xylene and toluene as the organic solvent component, and adjusting the nonvolatile content to 50% by mass.

The above-mentioned repair agent 1 was sufficiently rubbed with a roller onto the solvent-type acrylic resin top coat layer of the multilayer elastic coating film in which repair peeling and blistering of the outer wall surface occurred. Further, after confirming that the organic solvent was volatilized, the repairing agent 2 was similarly rubbed to smooth the surface of the underlayer. After standing for a whole day, a new top coat layer was formed with a solvent type urethane resin, and the repair of the multilayer elastic coating film was completed.

Evaluation of Coating Film Evaluation of the coating film was carried out using a part of the outer wall surface one year after the repair, and the adhesion and the presence or absence of blister were evaluated as follows. <Adhesion> The powdery material and dirt on the outer wall coating film were removed, and a cutting line having a total length of 2 cm reaching the substrate was crossed into a cross using a cutter. Then, after adhering the transparent adhesive tape to the cut line so as to completely adhere thereto, the tape was peeled off at a stretch, and the adhesiveness was determined based on the state of peeling of the coating film. 10 points …………………………………………………………………………………………………………………………… 8 8-10 points less than 8 points are not noticeable and less than 8 points. There is peeling. (The lower the score, the greater the peeling.)
Judgment was made by comparing with a standard photograph according to 714-56. The blister size and density are scored according to Table 1 below.

[0025]

[Table 1]

The state of blistering of the multilayer elastic coating before repair is as follows:
Table 1 shows the two levels. Peeling occurred in some places, and the evaluation of adhesion was 4 points. On the contrary,
No peeling or blistering was observed in the multilayer elastic coating film repaired in this example. Table 2 shows the results.

Examples 2 to 7, Comparative Examples 1 to 3 Same as Example 1 except that the composition of the repair agent (polyisocyanate type, nonvolatile content) and the type of paint for the new top coat layer in Example 1 were changed. Then the outer wall was repaired. Table 2 shows the results.

[0028]

[Table 2]

As is clear from the results shown in Table 2, whether the outer wall repaired by this embodiment has no peeling or blisters,
If any, it was slight, and a good appearance was maintained.

[0030]

According to the method for repairing an outer wall of the present invention, a polyisocyanate compound and an organic solvent are contained on an old top coat layer requiring repair, and the nonvolatile content is 5 to 70% by mass.
Is rubbed with a roller, the old coating film is redissolved, and then cured to form an underlayer. That is, the re-dissolved resin component reacts with the polyisocyanate component in the repair agent and cures to form a new underlayer.

Therefore, according to the repair method of the present invention, it is possible to perform repair without peeling off the top coat layer at all, or even without peeling off the top coat layer so completely. Therefore, there is no need to remove the old top coat layer by using kerosene or the like, which has conventionally been very troublesome.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Saito 4-1-1-15 Minamishinagawa, Shinagawa-ku, Tokyo F-term in Japan Paint Co., Ltd. (Reference) 2E176 AA05 BB04 4D075 AE07 AE08 AE15 BB20X CA47 DA27 DB43 DB50 DC02 EB38 EC07 EC37

Claims (3)

[Claims] Claims 1. A repair agent containing a polyisocyanate compound and an organic solvent and having a nonvolatile content of 5 to 70% by mass is rubbed with a roller on an old top coat layer requiring repair, and the old coating film is redissolved. A method for repairing an outer wall coating, comprising forming an underlayer by curing, and forming a topcoat layer on the underlayer. 2. The repairing agent used in the rubbing step is performed twice, the non-volatile content (NVa) of the repairing agent (a) used in the first rubbing step is 5 to 50% by mass, and the repairing agent used in the subsequent rubbing step. The method for repairing an exterior wall coating according to claim 1, wherein the nonvolatile content (NVb) of (b) is 10 to 70% by mass and NVa ≤ NVb. 3. The method according to claim 1, wherein the polyisocyanate compound is a burette type isocyanate prepolymer.