One-component moisture-curing paint

Abstract

Provided is a novel one-component moisture-curing coating material for treating concrete panels that has good concrete release properties and is capable of forming a highly durable coating film. The present invention relates to a one-component moisture-curing paint for treating concrete panels, which contains a urethane prepolymer and a moisture-curing latent curing agent.

Description

[Technical Field]

[0001] The present invention provides Formwork plywood for manufacturing concrete products (hereinafter referred to as Concrete panels Also called This relates to paints for treating [Background technology]

[0002] Conventionally, paint has been applied to the surface of concrete panels to improve the release properties of the concrete.

[0003] As such a paint, for example, a paint containing (A) animal and vegetable oil and (B) a fatty acid polyoxyethylene glycerin ester having a linear / branched alkyl group with carbon numbers of C8 to C22 has been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-131464 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional paints for treating concrete panels have insufficient concrete release properties, which can leave concrete on the concrete panel, preventing the production of good concrete products, and the need to clean the concrete panel after application is time-consuming. Furthermore, the paint film does not adhere well to the surface of the concrete panel, which can easily peel or crack, necessitating frequent reapplication of the paint.

[0006] An object of the present invention is to provide a novel one-component moisture-curing coating material for treating concrete panels, which has good concrete release properties and is capable of forming a highly durable coating film. [Means for solving the problem]

[0007] As a result of intensive research aimed at solving the above problems, the inventors discovered that a one-component moisture-curing paint for treating concrete panels, which contains a urethane prepolymer and a moisture-curing latent curing agent, is suitable for surface treatment of concrete panels, and thus completed the present invention.

[0008] That is, the present invention is as follows. [1] A one-component moisture-curing paint for treating concrete panels, which contains a urethane prepolymer and a moisture-curing latent curing agent. [2] The one-component moisture-curing paint for treating concrete panels according to [1] above, characterized in that the pencil hardness after curing is HB or higher. [3] The one-component moisture-curing paint for treating concrete panels according to [1] or [2] above, characterized in that the urethane prepolymer is a composite of diphenylmethane diisocyanate and a polyol containing polytetramethylene glycol. [4] The one-component moisture-curing coating material for treating concrete panels according to [3] above, characterized in that the reactivity ratio (NCO / OH) of the hydroxyl group (OH) of the polyol to the isocyanate group (NCO) of the polyisocyanate is 3 to 10. [5] A one-component moisture-curing paint for treating concrete panels according to [3] or [4] above, characterized in that the molecular weight of the polytetramethylene glycol is 1,000 or less. [6] The one-component moisture-curing paint for treating concrete panels according to any one of [3] to [5] above, characterized in that the diphenylmethane diisocyanate is a mixture of diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-2,2'-diisocyanate. [7] The one-component moisture-curing coating material for treating concrete panels according to any one of [1] to [6] above, further comprising a trialkoxysilane and / or a condensate thereof. [8] The one-component moisture-curing paint for treating concrete panels according to [7] above, wherein the trialkoxysilane is vinyltrimethoxysilane.

[0009] [9] A concrete panel having a layer of the cured product of the one-component moisture-curing coating material for treating concrete panels according to any one of [1] to [8] above on its surface.

[10] A method for producing a surface-treated concrete panel, comprising applying the one-component moisture-curing coating material for treating concrete panels according to any one of [1] to [8] above to the surface of a concrete panel and curing it.

[11] A method for treating the surface of a concrete panel, comprising applying the one-component moisture-curing coating material for treating a concrete panel according to any one of [1] to [8] above to the surface of a concrete panel and curing the coating material. [Effects of the Invention]

[0010] The one-component moisture-curing paint for treating concrete panels of the present invention has good concrete releasability and can form a highly durable coating film. DETAILED DESCRIPTION OF THE INVENTION

[0011] <paint> The one-component moisture-curing paint for treating concrete panels of the present invention (hereinafter sometimes simply referred to as a paint for treating concrete panels) is characterized by containing a urethane prepolymer and a moisture-curing latent curing agent.

[0012] The paint for treating concrete panels of the present invention has good concrete release properties. That is, it can suppress the adhesion of concrete to concrete panels. Therefore, good concrete products can be produced, and cleaning of the concrete panels after application is easy. In addition, it has high adhesion to concrete panels, is resistant to peeling and cracking of the coating film, and is highly durable. Therefore, there is no need to frequently repaint the paint, and it can be reused, for example, 10 or more times.

[0013] In addition, because it is a one-component paint, there is no need for mixing before application as with two-component paints, improving work efficiency. Also, because it is a moisture-curing paint, a uniform coating is formed by natural drying.

[0014] Furthermore, the coating material of the present invention has weather resistance and stain resistance, and exhibits stable performance even in outdoor environments. When used on metal substrates such as steel plates, it also exhibits anti-rust effects.

[0015] The coating material for treating concrete panels of the present invention can be applied by a brush or roller, or by spraying with an air spray.

[0016] (urethane prepolymer) The urethane prepolymer in the present invention is an unreacted polyurethane precursor having an isocyanate group (-NCO) at the molecular terminal, obtained by reacting an excess of polyisocyanate with a polyol. For example, the reaction is preferably carried out at a reaction ratio (NCO / OH) of the isocyanate group (NCO) to the hydroxyl group (OH) of the polyol of 3.0 or more, more preferably 3 to 10.

[0017] The polyisocyanate used in the present invention is not particularly limited as long as it can react with a polyol to form a urethane prepolymer, and aliphatic, aromatic, alicyclic, or combinations thereof can be used. The polyisocyanate may be used alone or in combination of two or more kinds.

[0018] The polyisocyanate used in the present invention is preferably diphenylmethane diisocyanate (MDI). Examples of diphenylmethane diisocyanate include diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-2,2'-diisocyanate. Diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-2,2'-diisocyanate are preferred, and a mixture containing these three is particularly preferred. In particular, it is preferred that diphenylmethane-4,4'-diisocyanate accounts for 30 to 70 mass% of the total MDI.

[0019] The polyol used in the present invention is not particularly limited as long as it can react with polyisocyanate to form a urethane prepolymer, and examples thereof include polyether polyols, polyester polyols, polycarbonate polyols, polyacrylic polyols, etc. The polyols may be used alone or in combination of two or more.

[0020] The polyol used in the present invention is preferably a polyether polyol, and among these, polytetramethylene glycol (PTMG), which has particularly high cohesive strength, is particularly preferred.

[0021] That is, in the present invention, it is preferable to use a polyol containing polytetramethylene glycol. The molecular weight of polytetramethylene glycol (PTMG) is preferably 5,000 or less, more preferably 3,000 or less, and even more preferably 1,000 or less. In particular, using polytetramethylene glycol having a molecular weight of 1,000 or less is preferable in that high strength of the coating film can be obtained. Here, the molecular weight means the weight average molecular weight converted into polystyrene as measured by gel permeation chromatography.

[0022] Specifically, a suitable example of the urethane prepolymer of the present invention is a compound of diphenylmethane diisocyanate and a polyol containing polytetramethylene glycol.

[0023] (Moisture-curing latent curing agent) The moisture-curable latent curing agent in the present invention reacts with moisture in the air after application to promote the crosslinking reaction of the urethane prepolymer. The moisture-curable latent curing agent is preferably an oxazolidine compound or an aldimine compound. The amount of the moisture-curable latent curing agent added is preferably such that NCO / (oxazolidine group or aldimine group)=0.5 to 1.0.

[0024] (trialkoxysilane) The coating material for treating concrete panels of the present invention preferably further contains trialkoxysilane and / or a condensate thereof, which can improve the storage stability of the urethane resin composition of the present invention.

[0025] Examples of trialkoxysilanes include vinyltrimethoxysilane, methyltrimethoxysilane, phenyltrimethoxysilane, and epoxy group-containing trimethoxysilane.

[0026] (solvent) Examples of solvents contained in the coating material for treating concrete panels of the present invention include aromatic hydrocarbons and ethers. Examples include aromatic hydrocarbons such as toluene, xylene, Solvent Naphtha 100, and Solvent Naphtha 150; hydrogenated high-boiling aromatic solvents such as Swaclean 150; carbonate solvents such as dimethyl carbonate, diethyl carbonate, and ethylene carbonate; and ethers such as diethyl ether, dimethyl ether, ethylene glycol mono-n-butyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination. The amount of solvent used in the one-component moisture-curable urethane resin composition is 10 to 50% by mass, from the viewpoints of ensuring coating thickness and workability.

[0027] (additives) The coating material for treating concrete panels of the present invention may contain commonly used additives. Specific examples include leveling agents, curing accelerators, rust inhibitors, antioxidants, antifoaming agents, preservatives, ultraviolet absorbers, pigments, etc. These additives may be used alone or in combination of two or more.

[0028] <Method for manufacturing concrete panels and method for treating the surface of concrete panels> The method for producing a surface-treated concrete panel and the method for treating the surface of a concrete panel of the present invention are characterized by applying the above-mentioned paint for treating concrete panels to the surface of a concrete panel and allowing it to harden.

[0029] Here, the application of the present invention includes a process using a brush or roller, as well as a spraying process using an air spray or the like. After application, curing may be carried out by natural drying or by heating. This causes the urethane prepolymer to react with moisture in the air and crosslink, forming a coating film with physical strength.

[0030] The pencil hardness of the coating film obtained by curing the coating material for treating concrete panels of the present invention is preferably HB or higher, and more preferably H or higher. The pencil hardness can be measured in accordance with JIS K 5600-5-4:1999 General test methods for paints - Part 5: Mechanical properties of coating films - Section 4: Scratch hardness (pencil method). [Example]

[0031] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0032] <Preparation of the Urethane Resin Composition of the Present Invention> Example 1 A 1000 ml separable flask equipped with a stirring blade was charged with 60 g of polytetramethylene glycol (PTMG650, hydroxyl value 171.5 mg KOH / g, manufactured by Mitsubishi Chemical Corporation), 10 g of polycarbonate polyol (Nippolan 981, hydroxyl value 112.0 mg KOH / g, manufactured by Tosoh Corporation), 10 g of polypropylene triol (Sanix GP1000, hydroxyl value 160.0 mg KOH / g, manufactured by Sanyo Chemical Industries, Ltd.), and 20 g of acrylic polyol (ARUFON UH-2401, hydroxyl value 120.0 mg KOH / g, manufactured by Toagosei Co., Ltd.), and the mixture was dried under reduced pressure at 100°C for 4 hours. After cooling, 40 g of an aromatic high-boiling solvent (Ipzol 100, manufactured by Idemitsu Co., Ltd.), 50 g of dimethyl carbonate, and 125 g of carbodiimide-modified MDI (Millionate MX, NCO% 29.2%, manufactured by Tosoh Corporation) were added, and the mixture was gradually heated to 80 ° C. under a nitrogen atmosphere and reacted at 80 ° C. for 2 hours. After that, 30 g of 2-isopropyl-3-(2-hydroxyethyl)oxazolidine was added, and the mixture was reacted at 60 ° C. for 1 hour. After cooling, 200 g of vinylsilane, 3.0 g of a leveling agent (Polyflow KL-401, manufactured by Kyoeisha Chemical Co., Ltd.), and 1 g of octylic acid as a curing accelerator were added and stirred to prepare a one-component moisture-curing concrete panel treatment paint according to Example 1.

[0033] <evaluation> (Concrete adhesion prevention (mold release) test) The one-component moisture-curing concrete panel treatment paint (hereinafter simply referred to as the paint) according to Example 1 was applied to a plywood formwork in a film thickness of approximately 1 mm using a roll, and then allowed to dry and harden for one day (check that it was dry). Subsequently, ordinary mortar was used for pouring and demolding, and the formwork after construction was visually evaluated for its ability to prevent concrete adhesion. The evaluation criteria are shown below, and the results are shown in Table 1.

[0034] (Evaluation criteria) ◎: No adhesion of concrete observed ○: Almost no adhesion to concrete observed △: Concrete adhesion is observed in some areas ×: Clear adhesion of concrete is observed

[0035] (Paint adhesion test to concrete panel) As in the above test, the paint of Example 1 was applied to a plywood formwork, and ordinary mortar was used to pour the paint into the formwork, followed by removal of the formwork. After construction, the formwork was visually inspected for peeling, lifting, swelling, or peeling from the substrate of the paint film. The evaluation criteria are shown below, and the results are shown in Table 1.

[0036] (Evaluation criteria) ○: No peeling of the coating film is observed △: Some lifting or peeling is observed in the coating ×: Extensive peeling of the coating film is observed

[0037] (Repeated use test) As in the above test, the paint according to Example 1 was applied to a plywood formwork, and ordinary mortar was used to repeatedly pour and remove the formwork. This was repeated until either the adhesion prevention property or the adhesion property was rated as "x", and the number of repetitions was evaluated. Note that if the evaluation was "x" after one application, the number of repetitions was 0.

[0038] (Storage stability test) 90 g of the paint according to Example 1 was placed in a 100 ml glass bottle and left in an oven at 60° C. for 3 days, after which the viscosity was measured. The evaluation criteria are shown below, and the results are shown in Table 1.

[0039] (Evaluation criteria) ○: Viscosity increase was less than 10% and the liquid state was maintained △: Viscosity increase was less than 50%, and slight viscosity change was observed, but the liquid state was maintained ×: Viscosity increase of 50% or more, hardening of the liquid was observed

[0040] (Rust prevention test for steel panel) The paint according to Example 1 was applied to a steel formwork panel and allowed to harden. On the first day of hardening, watering (0.5 mm / h) was performed twice for 1 hour. After leaving the panel for 20 days after hardening, the formwork surface was visually observed to check for the occurrence of red rust. The evaluation criteria are shown below, and the results are shown in Table 1.

[0041] (Evaluation criteria) ○: No rust ×: Rust present

[0042] Example 2 A urethane resin composition (Example 2) was prepared in the same manner as in Example 1, except that the amount of MDI was changed to 208 g, the amount of curing agent was changed to 60 g, and the NCO / OH ratio was changed to 5.2, and various evaluations were carried out.

[0043] Example 3 A urethane resin composition (Example 3) was prepared in the same manner as in Example 1, except that the amount of MDI was changed to 291 g, the amount of curing agent was changed to 91 g, and the NCO / OH ratio was changed to 7.3, and various evaluations were carried out.

[0044] Example 4 A urethane resin composition (Example 4) was prepared in the same manner as in Example 1, except that the amount of MDI was changed to 375 g, the amount of curing agent was changed to 120 g, and the NCO / OH ratio was changed to 9.4, and various evaluations were carried out.

[0045] Example 5 A urethane resin composition (Example 5) was prepared in the same manner as in Example 3, except that the MDI was changed to 255 g of pure MDI (Millionate MT, manufactured by Tosoh Corporation), and various evaluations were carried out.

[0046] Example 6 A urethane resin composition (Example 6) was prepared in the same manner as in Example 3, except that the MDI was changed to 268 g of polymeric MDI (Millionate MR-200, manufactured by Tosoh Corporation) with an NCO / OH ratio of 7.1, and various evaluations were carried out.

[0047] Example 7 A urethane resin composition (Example 7) was prepared in the same manner as in Example 3, except that the MDI was changed to 266 g of isomer-containing MDI (Millionate NM, 4,4' / (4,2'+2,2')=45 / 55, manufactured by Tosoh Corporation) with an NCO / OH ratio of 7.7, and various evaluations were carried out.

[0048] Example 8 A urethane resin composition (Example 8) was prepared in the same manner as in Example 3, except that the MDI was changed to 225 g of isophorone diisocyanate (IPDI) (manufactured by Evonik), and various evaluations were carried out.

[0049] Example 9 A urethane resin composition (Example 9) was prepared in the same manner as in Example 3, except that the curing agent was changed to 94 g of aldimine (a compound of 1 mol of isophoronediamine and 2 mols of benzaldehyde), and various evaluations were carried out.

[0050] Example 10 A urethane resin composition (Example 10) was prepared in the same manner as in Example 3, except that the silane compound was changed to epoxy silane, and various evaluations were carried out.

[0051] Example 11 A urethane resin composition (Example 11) was prepared in the same manner as in Example 3, except that the silane compound was changed to phenyltrimethoxysilane, and various evaluations were carried out.

[0052] Example 12 A urethane resin composition (Example 12) was prepared in the same manner as in Example 3, except that the amount of MDI was changed to 104 g and the NCO / OH ratio was changed to 2.5, and various evaluations were carried out.

[0053] (Comparative Example 1) Each evaluation was carried out using a self-crosslinking acrylic emulsion, Semiflon Aqua, 3-minute gloss (manufactured by KF Chemical Co., Ltd.). After application to the plywood formwork, it was dried at 23°C for 14 days to harden.

[0054] [Table 1]

[0055] As shown in Table 1, the one-component moisture-curing paints for treating concrete panels according to Examples 1 to 12 showed good results in all evaluation items including concrete adhesion prevention (mold releasability), adhesion to concrete panels, application durability, and storage stability. They also had rust prevention properties. [Industrial Applicability]

[0056] The one-component moisture-curing coating material for treating concrete panels of the present invention is industrially useful because it can be used as a coating material for architectural concrete panels.

Claims

1. A paint to be applied to plywood forms for manufacturing concrete products, Contains a urethane prepolymer and a moisture-curing latent curing agent, the urethane prepolymer is a compound of diphenylmethane diisocyanate and a polyol containing polytetramethylene glycol; The reaction ratio (NCO / OH) of the hydroxyl group (OH) of the polyol to the isocyanate group (NCO) of the diphenylmethane diisocyanate is 3 to 10. A one-component moisture-curing paint characterized by:

2. 2. The one-component moisture-curing paint according to claim 1, wherein the molecular weight of said polytetramethylene glycol is 1,000 or less.

3. 2. The one-component moisture-curing coating material according to claim 1, wherein the diphenylmethane diisocyanate is a mixture of diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-2,2'-diisocyanate.

4. 2. The one-component moisture-curing paint according to claim 1, further comprising a trialkoxysilane and / or a condensate thereof.

5. 5. The one-component moisture-curing coating according to claim 4, wherein the trialkoxysilane is vinyltrimethoxysilane.

6. A plywood formwork for producing concrete products, characterized in that it has a layer of the cured product of the one-component moisture-curing paint according to any one of claims 1 to 5 on its surface.

7. A method for producing formwork plywood for producing surface-treated concrete products, comprising applying the one-component moisture-curing paint according to any one of claims 1 to 5 to the surface of formwork plywood and curing it.

8. A method for treating the surface of formwork plywood for producing concrete products, comprising applying the one-component moisture-curing paint according to any one of claims 1 to 5 to the surface of formwork plywood and curing the paint.

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