JP7288575B2 - Urethane coating composition, coating structure and construction method - Google Patents

Description

The present invention relates to urethane coating compositions, coating structures and methods of application.

For example, on the roof, outer wall, etc. of a building, a structure in which the target surface is covered with a coating layer composed of a polyurethane resin is sometimes used for the purpose of waterproofing, peeling prevention, sealing, etc. (for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-295428

In recent years, the covering structure is required to reduce the impact on the environment and to improve the safety of work.

An object of one aspect of the present invention is to provide a urethane coating material composition, a coating structure, and a construction method capable of suppressing adverse effects on the environment and improving work safety.

One aspect of the present invention provides a urethane coating composition comprising a polyurethane-based resin containing a polyisocyanate compound containing a non-MDI polyisocyanate and having a theoretical MDI monomer content of 0% by mass.

Preferably, said non-MDI polyisocyanate is XDI.

Another aspect of the present invention provides a coating structure comprising a coating layer formed from the urethane coating composition.

Yet another aspect of the present invention is the preparation of a urethane coating composition composed of a polyurethane-based resin having a theoretical MDI monomer content of 0% by mass, using a polyisocyanate compound containing a non-MDI polyisocyanate. and a coating layer forming step of forming a coating layer covering a surface to be coated with the urethane coating material composition.

The polyisocyanate compound is preferably composed of non-MDI polyisocyanate only.

In the application method, the polyisocyanate compound includes non-MDI polyisocyanate and MDI, and the preparation step includes a first step of reacting a portion of the polyisocyanate compound with a curing agent to obtain an intermediate compound. and a second step of obtaining the urethane coating material composition using the intermediate compound and the other part of the polyisocyanate compound, wherein the entire amount of the MDI is used as the polyisocyanate compound in the first step. may be used.

According to one aspect of the present invention, there is provided a urethane coating material composition, a coating structure, and a construction method capable of suppressing adverse effects on the environment and enhancing work safety.

It is a perspective view which shows typically the covering structure by embodiment. It is explanatory drawing explaining the detail of the construction method by embodiment. It is explanatory drawing explaining the detail of the construction method by embodiment. It is explanatory drawing explaining the detail of the construction method by embodiment.

Hereinafter, urethane coating material compositions, coating structures, and construction methods according to embodiments will be described in detail with reference to the drawings.

[Coating structure]
FIG. 1 is a perspective view schematically showing a covering structure 10 according to an embodiment. As shown in FIG. 1 , the coating structure 10 includes a primer layer 1 , a coating layer 2 (waterproof coating layer), and a topcoat 3 . The covering structure 10 is a waterproof structure having a foundation 101 as a construction target.

The base 101 is, for example, a flat surface 103 surrounded by the parapet section 102 on the roof of the building and an inner surface (rising surface) 104 of the parapet section 102 . The foundation 101 is, for example, a surface to be constructed made of concrete.

The primer layer 1 is formed of a primer composed of, for example, polyurethane-based resin, epoxy-based resin, or the like. The primer layer 1 enhances the adhesion of the covering layer 2 to the substrate 101 .

The coating layer 2 is formed on the surface of the primer layer 1 with a urethane coating material composition composed of a polyurethane resin. The urethane coating material composition may be composed of a two-component polyurethane resin, or may be composed of a one-component (moisture-curable) polyurethane resin.

The two-liquid type urethane coating material composition contains a main agent containing a polyisocyanate compound and a curing agent.
The main component has, for example, an isocyanate group-terminated prepolymer containing a polyisocyanate compound as a main component. The isocyanate group-terminated prepolymer is a polymer having an isocyanate group at the molecular end. The isocyanate group-terminated prepolymer is obtained, for example, by reacting a polyisocyanate compound and a polyol compound. The term "main component" means that the ratio (by mass) of the component in the main agent exceeds 50%.
A polyisocyanate compound may be used as the main agent.

Polyisocyanate compounds include non-MDI polyisocyanates. A "non-MDI polyisocyanate" is a polyisocyanate other than MDI. MDI here means, for example, 4,4′-diphenylmethane diisocyanate (4,4′-MDI), 2,4′-diphenylmethane diisocyanate (2,4′-MDI), 2,2′-diphenylmethane diisocyanate (2 , 2′-MDI).

Non-MDI polyisocyanates include xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI), tolidine diisocyanate (TODI), 1,5-naphthalene diisocyanate (NDI), triphenylmethane triisocyanate, 1,4-phenylene diisocyanate, aromatic polyisocyanate such as polymethylene polyphenylene polyisocyanate; norbornane diisocyanate (NBDI), aliphatic polyisocyanate such as lysine diisocyanate; isophorone diisocyanate (IPDI), bis(isocyanatomethyl)cyclohexane (H6XDI), dicyclohexylmethane diisocyanate (H12MDI) ), and alicyclic polyisocyanates such as transcyclohexane-1,4-diisocyanate.

The non-MDI polyisocyanate may be a cyclized trimer (isocyanurate modified product), biuret modified product, allophanate modified product, etc. of the above polyisocyanate compound.
Examples of non-MDI polyisocyanates include adduct modified products of the above polyisocyanate compounds and polyol compounds. Examples of the polyol compound include ethylene glycol, 1,4-butanediol, propylene glycol, dipropylene glycol, trimethylolpropane, polyether polyol, polymer polyol, polytetramethylene ether glycol, polyester polyol, acrylic polyol, and polyalkadiene polyol. , hydrides of polyalkadiene polyols, partially saponified ethylene-vinyl acetate copolymers, pepper oil-based polyols, and the like can be used.
These non-MDI polyisocyanates may be used alone or in combination of two or more.

Xylylene diisocyanate (XDI) is preferred as the non-MDI polyisocyanate. Since XDI is a substance that has little adverse effect on the human body, the use of XDI can reduce the impact on the environment and improve work safety.

The polyisocyanate compound preferably comprises only non-MDI polyisocyanates, but MDI may be used as well as non-MDI polyisocyanates. That is, as the polyisocyanate compound, a non-MDI polyisocyanate and MDI may be used in combination.
The blending amount of the constituent components of the polyisocyanate compound is determined so that the theoretical content of the MDI monomer in the urethane coating material composition, which is the final product, is 0% by mass. MDI monomer may also be referred to as free MDI, unreacted MDI, or residual MDI, as it has not reacted with active hydrogen groups such as curatives.

The polyol compound used for the isocyanate group-terminated prepolymer is not particularly limited as long as it has two or more active hydrogen groups in one molecule. The active hydrogen groups react with the isocyanate groups of the polyisocyanate compound.
Polyol compounds include, for example, polyether polyols, polyester polyols, polytetramethylene glycol and the like. Examples of polyether polyols include polypropylene ether diol (polypropylene glycol: PPG) and polypropylene ether triol. These polyol compounds may be used alone or in combination of two or more.

The curing agent contains a compound having two or more active hydrogen groups in one molecule. The active hydrogen groups react with the isocyanate groups of the polyisocyanate compound. Examples of the curing agent include polyamine compounds, polyol compounds, and water.
Examples of the polyamine compounds include aromatic polyamines and aliphatic polyamines. Specifically, diethyltoluenediamine, dialkyl-4,4′-methylenedianiline, tetraalkyl-4,4′-methylenedianiline, 4,4′-methylenebis(2-chloroaniline), bismethylthiotoluenediamine, Polyoxyalkylenediamine, m-xylylenediamine, ethylenediamine, isophoronediamine and the like can be mentioned. These polyamine compounds may be used alone or in combination of two or more.
As the polyol compound, the aforementioned polyol compounds can be used.

One-liquid (moisture-curable) urethane coating compositions can be classified into two types. One is a type in which the moisture in the air reacts directly with the isocyanate component in the urethane coating composition to cure. This type is called the first type. The other is the type that contains at least two components, Component 1 and Component 2, in the urethane coating composition. Component 2 does not react with component 1, but becomes component 2' with moisture in the air, and component 2' reacts with component 1 to proceed curing. Component 2 is generally referred to as a latent hardener. This type is called the second type.

The first type of waterproof material includes, for example, the aforementioned polyisocyanate compound and the aforementioned polyol compound. The first type waterproof material may be, for example, an isocyanate group-terminated prepolymer obtained by reacting the aforementioned polyisocyanate compound and the aforementioned polyol compound.

The second type of waterproof material contains, for example, the aforementioned polyisocyanate compound (component 1) and a latent curing agent (component 2). Component 1 may be, for example, an isocyanate group-terminated prepolymer obtained by reacting the aforementioned polyisocyanate compound with the aforementioned polyol compound.

A latent curing agent reacts with moisture to generate an active hydrogen group. Examples of latent curing agents include hydrolytic latent curing agents and thermal latent curing agents. A hydrolyzable latent curing agent does not function as a curing agent in an environment without water, but hydrolyzes and functions as a curing agent in the presence of water (humidity). Examples of hydrolyzable latent curing agents include oxazolidine compounds and ketimine compounds. The heat-latent curing agent does not function as a curing agent at room temperature, but functions as a curing agent by melting, dissolving or activating when heat is applied above a certain level. Examples of heat-latent curing agents include dicyandiamide and imidazoles.

The theoretical content of the MDI monomer in the polyurethane resin constituting the urethane coating composition is 0% by mass. Therefore, it is possible to suppress the influence on the environment and improve the safety of the work.

The urethane coating composition may optionally contain plasticizers, solvents, surfactants (antifoaming agents, filler dispersants, viscosity modifiers, etc.), pigments, dyes, fillers, curing acceleration catalysts, antioxidants, agents, UV absorbers, light stabilizers and various other additives can be added.

A top coat 3 is formed on the surface of the coating layer 2 . For the top coat 3, an acrylic resin (for example, an acrylic urethane resin, an acrylic silicone resin, etc.), a fluorine resin, a silicone resin, or the like can be used. The top coat 3 is formed for the purpose of protecting the coating layer 2 by shielding ultraviolet rays and the like, and improving the appearance of the coating structure 10 .

[Construction method]
The construction method of the embodiment has a preparation step and a coating layer forming step.

(Preparation process)
In the case of a two-liquid type urethane coating composition, the urethane coating composition is prepared by mixing the main agent and the curing agent. In the case of a one-liquid type urethane coating composition, a urethane coating composition is prepared by blending the aforementioned polyisocyanate compound. The urethane coating material comprising the urethane coating material composition is preferably liquid.

When the aforementioned polyisocyanate compound is composed only of non-MDI polyisocyanate, MDI is not used, so the polyurethane-based resin constituting the urethane coating material composition does not contain MDI monomer. The theoretical content of the MDI monomer in the polyurethane resin is 0% by mass.

When a non-MDI polyisocyanate and MDI are used together as the aforementioned polyisocyanate compound, the preparation process has a first step and a second step.
In the first step, an intermediate formulation is obtained by mixing a portion of the polyisocyanate compound with the aforementioned curing agent. Polyisocyanate compounds used herein include MDI. The entire amount of MDI is used in the first step and not used in the second step.

The mixing ratio of the polyisocyanate compound and the curing agent in the first step is, for example, the equivalent ratio (NCO group/OH group) between the isocyanate group of the polyisocyanate compound and the active hydrogen group (hydroxyl group) of the curing agent is 2 or less. is determined to be As a result, the isocyanate groups of the polyisocyanate compound and the active hydrogen groups of the curing agent are equivalent (i.e., conditions under which they react without excess or deficiency), or conditions in which the active hydrogen groups are excessive with respect to the isocyanate groups. react with.

Among the polyisocyanate compounds, MDI is used under the condition that the equivalent ratio (NCO group/OH group) is 2 or less, so theoretically, the entire amount thereof reacts with the curing agent and the like. Therefore, the theoretical content of MDI monomer in the reaction product (intermediate compound) is 0% by mass.

For example, when the monomer (OCN-R-NCO), which is a polyisocyanate compound, and the polyol compound (HO-R'-OH) are blended so that the equivalent ratio (NCO group/OH group) is 2, the following As shown in the formula, the total amount of the monomer theoretically reacts with the polyol compound. Therefore, the theoretical content of the monomer in the reaction product (intermediate compound) is 0% by mass.

Intermediate formulations may be measured for MDI monomer content. As a measuring method, for example, a method conforming to JIS K1603-1 (2007) can be adopted. This confirms that the content of MDI monomer in the intermediate formulation is sufficiently low.

In the second step, the intermediate composition and the other portion of the polyisocyanate compound (the remaining portion of the polyisocyanate compound) are used to obtain a urethane coating material composed of the urethane coating composition. In this step, for example, the intermediate compound and the other part of the polyisocyanate compound are mixed. Another portion of the polyisocyanate compounds are non-MDI polyisocyanates, such as XDI.
The equivalent ratio of isocyanate groups to active hydrogen groups (NCO groups/OH groups) in the mixture is higher than in the intermediate compound. This equivalent ratio (NCO groups/OH groups) is greater than 2, for example.

Depending on the type of polyisocyanate compound, the viscosity of the urethane coating can be lowered by mixing the intermediate formulation with other parts of the polyisocyanate compound (eg, XDI). As a result, the handleability of the urethane coating material is improved.

As described above, in the first step, the theoretical content of MDI monomer in the intermediate formulation is 0% by mass, so the theoretical content of MDI monomer in the final urethane coating material composition is also 0% by mass. . Thus, a urethane coating with a very low MDI monomer content is obtained.

(Coating layer forming step)
The urethane coating material forms a coating layer that covers the surface to be applied. This process will be described in detail below with reference to FIGS. 2 to 4 are explanatory diagrams explaining the details of the construction method according to the embodiment.

As shown in FIG. 2, a primer layer 1 is formed by applying a primer to a substrate 101 .
As shown in FIG. 3, the coating layer 2 is formed by applying the urethane coating material to the surface of the primer layer 1 . The covering layer 2 covers at least a partial area of the underlayer 101 .

The urethane coating material can be applied by hand coating, pressure feeding hand coating, pressure feeding blowing (spray), or the like. In the case of hand coating, for example, the urethane coating material is spread over the substrate 101 using a roller, rake, trowel, or the like. In the case of pressure-feeding hand coating, the urethane coating material discharged from a pressure-feeding pump-equipped coating device is spread over the substrate 101 . In the case of pressurized spraying, a urethane coating material that is sent from a coating apparatus with a pressurized pump and sprayed from a spray nozzle is sprayed onto the substrate 101 .

As shown in FIG. 4, a topcoat 3 is formed by applying a coating material to the surface of the coating layer 2 . A covering structure 10 is thereby obtained.

Since the urethane coating material composition has a low MDI monomer content, it is possible to suppress adverse effects on the environment and improve work safety.

In the coating structure 10 shown in FIG. 1, the coating layer 2 is formed by a urethane coating material with a low MDI monomer content. Therefore, it is possible to suppress adverse effects on the environment and improve work safety.

According to the construction method, since the urethane coating material having a low content of MDI monomer is used, it is possible to suppress adverse effects on the environment and improve work safety.

The polyisocyanate compound is preferably composed only of non-MDI polyisocyanate. As a result, the content of the MDI monomer in the urethane coating material composition can be reduced, which is advantageous in terms of environmental impact and work safety.

When a non-MDI polyisocyanate and MDI are used together as the polyisocyanate compound, if the entire amount of MDI is used in the first step of the preparation process, the content of the MDI monomer in the urethane coating material composition as the final product rate can be low enough. In this case, since inexpensive MDI is used as part of the polyisocyanate compound, cost reduction is possible.

As described above, the urethane coating material composition, coating structure, and construction method according to the embodiments of the present invention have been described, but the present invention is not limited to the above-described embodiments, and can be freely modified within the scope of the present invention. .
In the construction method of the above embodiment, the coating layer was formed by applying the urethane coating material composition, but the coating layer is not limited to the coating film. The coating layer may be formed into a sheet prior to construction. In this case, a sheet-like coating layer is laid on the construction target surface.
The mixing ratio of the polyisocyanate compound and the curing agent is such that the equivalent ratio (NCO group/OH group) of the isocyanate group of the polyisocyanate compound and the active hydrogen group (hydroxyl group) of the curing agent is 1.5 or less, or 1 or less. It may be determined so that

In the covering structure of the above embodiment, the concrete foundation on the roof of the building was exemplified as a construction target, but the construction target is not limited to this. The construction target may be a wall surface of a concrete structure, an inner surface of a water shielding work, an outer surface of a bridge pier, a ground surface, or the like.
In the covering structure of the above-described embodiment, the covering layer is used as a waterproof layer (see FIG. 1), but the construction purpose is not particularly limited. waterproofing, ensuring airtightness, etc.).

2 covering layer 10 covering structure

Claims (1)

A method for producing a urethane coating composition, the method comprising:
a first step of reacting MDI with a curing agent containing a polyol compound and water to obtain an intermediate formulation; and a second step of reacting XDI with the intermediate formulation to obtain a urethane coating composition. death,
The total amount of the MDI is consumed in the first step, so that the theoretical content of the MDI monomer in the urethane coating composition is 0% by mass,
A method for producing a urethane coating material composition, wherein the urethane coating material composition is used for a concrete construction target surface having a raised surface.

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