JP2025028798A - One-component moisture-curing urethane resin composition and coating material using same - Google Patents

Abstract

To provide a one-pack moisture-curable urethane resin composition that excels in storage stability and curability as one liquid, and exhibits sufficiently high weather resistance and impact resistance after curing, and a coating material prepared using the same.SOLUTION: Disclosed is a one-pack moisture-curable urethane resin composition comprising a urethane prepolymer and oxazolidine, wherein the urethane prepolymer is synthesized from a polyisocyanate and a polyol, which comprises a polycarbonate polyol (PC) and an acrylic polyol (AC) with a hydroxyl value of 60-150 mgKOH/g. Also disclosed is a coating material comprising the one-pack moisture-curable urethane resin composition and an aromatic solvent and/or an ether-based solvent.SELECTED DRAWING: None

Description

The present invention relates to a one-component moisture-curing urethane resin composition and a coating material using the same. More specifically, the present invention relates to a one-component moisture-curing urethane resin composition having excellent weather resistance and a coating material using the same.

One-component moisture-curing urethane resins are used in adhesives, paints, coating materials, sealants, etc., due to their adhesion to substrates, ease of adjusting physical properties, and ease of handling. Here, a high level of weather resistance is required of urethane resins, particularly in paints and coating materials that are exposed directly to sunlight. On the other hand, paints and coating materials also require durability against external forces, such as impact resistance.

As a one-component moisture-curing urethane resin with excellent weather resistance, Patent Document 1 proposes one that contains a resin made of acrylic polyol and hydroxyl-containing oxazolidine, and a urethane prepolymer. This is a resin made of acrylic polyol, polyisocyanate, and hydroxyl-containing oxazolidine, and is expected to exhibit a certain degree of weather resistance. However, when used in paints, coating materials, etc., the resins used therein are required to have an even higher level of weather resistance, and urethane resins made of this composition do not have sufficient weather resistance.

On the other hand, as a highly weather-resistant coating composition, a urethane resin made of polycarbonate polyol, acrylic polyol, and polyisocyanate is widely known as a two-component curing type (Patent Document 2, etc.).

However, it is difficult to achieve both weather resistance and impact resistance with these compositions, and they do not suggest a one-component moisture-curing urethane resin composition.

JP 2002-20425 A Patent No. 7051971 JP 2021-98774 A JP 2021-98775 A JP 2020-94085 A JP 2016-113551 A JP 2016-785 A JP 2013-116993 A

The object of the present invention is to provide a one-component moisture-curable urethane resin composition that has excellent storage stability and curing properties as a one-component, and has excellent weather resistance and impact resistance after curing, and a paint using the same.

The object of the present invention is achieved by a one-component moisture-curing urethane resin composition comprising a urethane prepolymer and oxazolidine, the urethane prepolymer being synthesized from a polyol comprising a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH/g, and a polyisocyanate, and by a coating material containing the one-component moisture-curing urethane resin composition and an aromatic solvent and/or an ether solvent.

The urethane resin composition of the present invention has excellent storage stability as a one-part component, and because it has moisture curing properties, it cures with moisture in the air to form a cured product. Furthermore, the cured product of this one-part moisture curing urethane resin composition has excellent effects such as high weather resistance and impact resistance.

The urethane prepolymer used is a urethane prepolymer with isocyanate groups at the end, synthesized from polyol and polyisocyanate, with the polyol consisting of polycarbonate polyol (PC) and acrylic polyol (AC).

Examples of polycarbonate polyols include those obtained by reacting at least one aliphatic polyhydric alcohol, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, or cyclohexanedimethylol, with a dialkylene carbonate or dialkyl carbonate, such as diethylene carbonate, dimethyl carbonate, or diethyl carbonate. Here, the number of carbon atoms in the alkylene group or dialkyl group is 2 to 10. As such polycarbonate polyols, those having a number average molecular weight Mn of 500 to 3000 are preferably used, and commercially available products such as UBE products ETERNACOLL UH-50, UH-100, UH-200, UH-300, PH-50, PH-100, PH-200, PH-300, UC-100, UM-90U, and Tosoh products Nipporan 981, 980R, 982R, 965, 963, 964, 968 can be used as they are.

Examples of acrylic polyols with a hydroxyl value of 60 to 150 mgKOH/g include homopolymers or copolymers of (meth)acrylic monomers having hydroxyl groups, or copolymers of (meth)acrylic monomers having hydroxyl groups with other monomers having polymerizable unsaturated bonds, which have a specified hydroxyl value. The acrylic polyols used in one-component moisture-curing urethane resins preferably have an average of 2 to 8 hydroxyl groups per molecule.

Examples of (meth)acrylic monomers having a hydroxyl group include hydroxyalkyl (meth)acrylic acid esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, as well as (meth)acrylic acid monoesters of triols such as (meth)acrylic acid monoesters of trimethylolpropane. These may be used alone or in combination of two or more.

Other monomers having polymerizable unsaturated bonds can also be used in combination, such as alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, and 3-methoxybutyl (meth)acrylate; unsaturated carboxylic acids such as (meth)acrylic acid, maleic acid, and itaconic acid; unsaturated amides such as (meth)acrylamide and N-methylol (meth)acrylamide; styrene, vinyl toluene, vinyl acetate, and acrylonitrile. These may be used alone or in combination of two or more. Among these, from the viewpoint of weather resistance, (meth)acrylic acid esters such as alkyl (meth)acrylate and/or alkoxyalkyl (meth)acrylate are preferably used.

As polyisocyanates, aliphatic, aromatic or alicyclic polyisocyanates are used. For example, MDI (diphenylmethane diisocyanate), hydrogenated MDI, 1,5-naphthalene diisocyanate, tolylene diisocyanate, 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, tetramethylxylene diisocyanate (TMXDI), 1,8-diisocyanatomethyloctane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, bicycloheptane triisocyanate, and derivatives thereof (biuret, allophanate, isocyanurate), trimethylolpropane adduct, etc., and preferably, from the viewpoint of weather resistance, aliphatic polyisocyanates such as isophorone diisocyanate and their derivatives.

As the polyol, other polyols can be used to adjust the physical properties, as long as the weather resistance of the cured product is not impaired, specifically, in a proportion of less than 20 mass% of the total polyols. Here, if other polyols are used in a proportion of 20 mass% or more, it may become difficult to achieve both weather resistance and impact resistance, which is not preferable. Examples of such other polyols include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, trimethylolpropane, 1,2,5-hexanetriol, 1,3-butanediol, 1,4-butanediol, 4,4'-dihydroxyphenylpropane, 4,4'-dihydroxyphenylmethane, pentaerythritol propylene oxide, ethylene oxide, butylene oxide, styrene oxide, tetramethylene glycol, polytetramethylene glycol, polyoxypropylene polyol, etc., and preferably polytetramethylene glycol.

When synthesizing the urethane prepolymer, a hydroxyl group-containing oxazolidine can be used in a ratio of 0.5 equivalents or less to the remaining isocyanate groups. Examples of hydroxyl group-containing oxazolidine include hydroxyalkyl oxazolidines such as 2-isopropyl-3-(2-hydroxyethyl)oxazolidine, 2-(1-methylbutyl)-3-(2-hydroxyethyl)oxazolidine, N-hydroxyethyl-2-phenyloxazolidine, and 2-(p-methoxyphenyl)-3-(2-hydroxyethyl)oxazolidine, and 2-isopropyl-3-(2-hydroxyethyl)oxazolidine is preferred from the standpoints of storage stability, curing properties, and physical properties after curing. These hydroxyalkyl oxazolidines are synthesized by known methods from the corresponding aldehydes or ketones and hydroxyalkylamines.

The acrylic polyol to be used has a hydroxyl value of 60 to 150 mgKOH/g, and preferably has a glass transition temperature Tg of 0 to 60°C. The hydroxyl value of the acrylic polyol affects the viscosity of the urethane prepolymer, which in turn affects the workability of the paint. If the hydroxyl value is less than 60 mgKOH/g, the strength and weather resistance of the coating film tend to decrease. On the other hand, if the hydroxyl value exceeds 150 mgKOH/g, the impact resistance tends to decrease. In addition, the viscosity of the prepolymer increases, which is also a problem in prepolymer production. If the glass transition temperature Tg is less than 0°C, the impact resistance is excellent, but the weather resistance may decrease, while if it exceeds 60°C, the weather resistance is excellent, but the impact resistance may decrease.

The mass ratio of polycarbonate polyol (PC) and acrylic polyol (AC) that make up the urethane prepolymer, PC/AC, is 60/40 to 90/10, with the amount of PC exceeding the amount of AC. If these ratios are not met, it may be difficult to achieve both weather resistance and impact resistance.

In addition, the total amount of PC and AC in the polyol is 80% by mass or more, which makes it possible to provide a resin with excellent weather resistance and impact resistance.

Here, Patent Documents 3 to 8 disclose the combined use of PC and AC as polyols for synthesizing NCO group-containing prepolymers in moisture-curing urethane materials. However, none of these documents teach or suggest that weather resistance is improved by using an acrylic polyol with a hydroxyl value of 60 to 150 mgKOH/g.

The urethane prepolymer can also contain an oxazolidine compound in which a hydroxyl-containing oxazolidine has been reacted with a polyisocyanate in advance, preferably a compound in which a hydroxyl-containing oxazolidine (OH) has been reacted with an isocyanate group (NCO) in a ratio of NCO/OH = 1/0.1 to 1/1. Here, an aliphatic polyisocyanate is preferably used as the polyisocyanate.

The equivalent ratio of isocyanate groups (NCO) to oxazolidine groups (OX) in the urethane resin composition is preferably NCO/OX = 1.0 to 3.0. If the NCO/OX equivalent ratio is less than 1.0, the amount of oxazolidine will be in excess of the isocyanate groups, which will result in unreacted amino groups remaining during curing, causing poor weather resistance. On the other hand, if the NCO/OX equivalent ratio exceeds 3.0, the amount of oxazolidine groups, which are the curing agent, will be significantly less than the amount of isocyanate groups, causing poor curing properties.

The moisture-curable urethane resin composition consisting of the above components is dissolved in an aromatic solvent and/or an ether solvent to form a paint with a solids concentration of 40-80% by mass, from the viewpoints of ensuring coating thickness and workability.

Examples of solvents include aromatic hydrocarbons such as toluene, xylene, solvent naphtha 100, and solvent naphtha 150, 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 may be used alone or in combination of two or more.

Other additives may be used as appropriate, such as anti-aging agents, UV absorbers, pigments, thixotropic agents, anti-sagging agents, matting agents, and fillers. Here, preferred examples of thixotropic agents include finely powdered silica and amide-based thixotropic agents.

Next, the present invention will be explained using examples.

Example 1
(1) 66.7 g of propylene glycol monobutyl ether acetate was charged into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the mixture was heated to 92°C while replacing with nitrogen. Next, a mixture of 59.0 g of cyclohexyl methacrylate, 14.5 g of n-butyl acrylate, 14.0 g of 2-hydroxyethyl methacrylate, 12.5 g of 2-hydroxyethyl acrylate, and 2.9 g of tert-butylperoxy-2-ethylhexanoate was fed over 4 hours. One hour and two hours after the end of the feed, 0.2 g each of tert-butylperoxy-2-ethylhexanoate was added, and the mixture was allowed to react for another 2 hours to obtain acrylic polyol A.
(2) In a 500 ml separable flask equipped with a stirring blade, 35.0 g of dried polycarbonate diol (ETERNACOLL PH-200, hydroxyl value 56 mg KOH/g), 35.0 g of polycarbonate diol (Nippolan PC-982R, hydroxyl value 56 mg KOH/g), and 50.0 g (equivalent to 30.0 g) of acrylic polyol A (number average molecular weight Mn 1830, hydroxyl value 120 mg KOH/g, Tg 28°C, propylene glycol butyl ether acetate 60 mass% solution) were dissolved in 89.0 g of aromatic solvent (Shin Nippon Kagaku Products R100), and then 36.4 g of isophorone diisocyanate and 0.02 g of dibutyl dilaurate were added and stirred at room temperature for 1 hour, followed by 2-isopropyl-3-(2-hydroxyethyl)oxazolidine. The mixture was gradually heated to 80° C. in a nitrogen stream and reacted at 80° C. for 2 hours to obtain 250.4 g of urethane prepolymer A.

(3) Urethane prepolymer A 250.4g
Leveling agent (BYK Japan product 0.2g
BYK-UVUV3576)
UV absorber (Ciba-Geigy UV1164) 5g
Light stabilizer (Ciba-Geigy product HALS292) 5g
Hardener 13.9g
[2-isopropyl-3-(2-hydroxyethyl)
2 moles of oxazolidine and hexamethylene
Adduct with 1 mole of diisocyanate;
Molecular weight 486.68]
Octyl acid 0.03g
The mixture was thoroughly stirred to obtain a transparent one-component moisture-curable urethane resin composition A (viscosity 273 mPa·s at 25°C using an E-type viscometer at 100 rpm). The equivalent ratio of isocyanate group/oxazolidine group (NCO/OX) was 1.84.

(4) The obtained one-liquid moisture-curing urethane resin composition A was applied to a thickness of 0.3 mm on a Nichiha ceramic siding board coated with a urethane primer obtained by reacting 3.0 g of 3-aminopropyltriethoxysilane with 200.0 g of acrylic polyol (Toa Gosei product Alfon UH2041), 200.0 g of aromatic solvent (Shin-Nihon Kagaku product R100), 94.1 g of isophorone diisocyanate, and 0.3 g of dibutyl dilaurate to a thickness of 0.15 mm, and cured and aged for 2 weeks under an environment of 23 (± 2) ° C. and 50 (± 10) % RH to obtain a paint cured product on the siding board. Weather resistance test and impact resistance test were performed using the obtained paint cured product.

[Weather resistance test]
Testing equipment: Iwasaki Electric Co., Ltd. Eye Super UV Tester Testing conditions: UV illuminance: 150±8mW/ ^cm2
Temperature: 63°C
Wavelength: 295-450nm
Cycle: 63℃±3℃, 50% RH, 4 hours of exposure ⇒ 4 hours of condensation Test result evaluation: 1600 hours no change A, 1200 hours no change B, 800 hours no change
C: Whitening or cracking occurs after 800 hours. D:

[Impact resistance test]
Test method: JIS K5600-5-3 (1999) General test method for paints, Part 5: Mechanical properties of coating film, Section 3: Resistance to falling weight, based on DuPont method
The paint was applied to a thickness of 0.3 mm on a 2 mm thick acrylic resin cut to 50 mm x 50 mm, and left to harden and cure for 2 weeks in an environment of 23 (±2) °C and 50 (±10) % RH. Next, a 6.35 mm radius shot mold and a receiving stand were attached so that the coated surface was facing up, and a 300 g weight was dropped from a height of 40 cm, 30 cm, or 20 cm, and the appearance of the coating film was observed. Test result evaluation: A: no cracks in the coating film at a height of 40 cm, B: B at 30 cm, C: C at 20 cm, and D: D: D

Example 2
In Example 1, the amounts of the two types of polycarbonate polyols in (2) were each changed to 30 g, the amount of acrylic polyol A to 66.7 g (equivalent to 40 g), the amount of aromatic solvent to 85.3 g, and the amount of isophorone diisocyanate to 38.8 g, and further the amount of curing agent in (3) was changed to 16 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.78, viscosity at 25°C at 100 rpm with an E-type viscometer of 310 mPa s).

Example 3
In Example 1, the amounts of the two types of polycarbonate polyols in (2) were each changed to 40 g, the amount of acrylic polyol A to 33.3 g (equivalent to 20.0 g), the amount of aromatic solvent to 92.7 g, the amount of isophorone diisocyanate to 33.9 g, and the amount of curing agent in (3) to 11.6 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.92, viscosity at 25°C at 100 rpm with an E-type viscometer of 248 mPa s).

Example 4
In Example 1, the amounts of the two types of polycarbonate polyols in (2) were each changed to 45 g, the amount of acrylic polyol A to 16.7 g (equivalent to 10.0 g), the amount of aromatic solvent to 87.3 g, the amount of isophorone diisocyanate to 31.5 g, and the amount of curing agent in (3) to 9.5 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 2.01, viscosity at 25°C at 100 rpm with an E-type viscometer 218 mPa s).

Example 5
In Example 1, the amounts of the two types of polycarbonate polyols in (2) were each changed to 25 g, the amount of acrylic polyol A to 83.3 g (equivalent to 50.0 g), the amount of aromatic solvent to 83.3 g, the amount of isophorone diisocyanate to 41.4 g, and the amount of curing agent in (3) to 18 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.76, viscosity at 25°C at 100 rpm with an E-type viscometer 417 mPa s).

Example 6
In Example 1, the amounts of the two types of polycarbonate polyols in (2) were changed to 47.5 g each, the amount of acrylic polyol A to 8.3 g (equivalent to 5.0 g), the amount of aromatic solvent to 98.7 g, the amount of isophorone diisocyanate to 30.0 g, and the amount of curing agent in (3) to 8.3 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 2.04, viscosity at 25°C at 100 rpm with an E-type viscometer 203 mPa s).

Example 7
The amount of curing agent in Example 1(3) was changed to 7.0 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 2.71, viscosity at 25° C. at 100 rpm using an E-type viscometer 268 mPa·s).

Example 8
A one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.05, viscosity 285 mPa·s at 25° C. at 100 rpm using an E-type viscometer) was obtained by changing the amount of curing agent in Example 1(3) to 30.0 g.

Example 9
In Example 1, the amount of cyclohexyl methacrylate in (1) was changed to 55.0 g, the amount of n-butyl acrylate to 12.0 g, the amount of 2-hydroxyethyl methacrylate to 18.0 g, and the amount of 2-hydroxyethyl acrylate to 15.0 g, respectively, to obtain acrylic polyol B (number average molecular weight Mn 1860, hydroxyl value 150 mgKOH/g, Tg 30°C, propylene glycol butyl ether acetate 60 wt% solution), and the amount of acrylic polyol A in (2) was changed to the same amount of acrylic polyol B, the amount of aromatic solvent to 92.0 g, the amount of isophorone diisocyanate to 39.9 g, and the amount of curing agent in (3) to 16.8 g, respectively, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.78, viscosity at 25°C at 100 rpm with an E-type viscometer of 373 mPa·s).

Example 10
In Example 1, the amount of cyclohexyl methacrylate in (1) was changed to 67.0 g, the amount of n-butyl acrylate to 20.0 g, the amount of 2-hydroxyethyl methacrylate to 6.6 g, and the amount of 2-hydroxyethyl acrylate to 6.4 g, respectively, to obtain acrylic polyol C (number average molecular weight Mn 1840, hydroxyl value 60 mgKOH/g, Tg 26°C, propylene glycol butyl ether acetate 60 wt% solution), and the amount of acrylic polyol A in (2) was changed to the same amount of acrylic polyol C, the amount of aromatic solvent to 81.0 g, the amount of isophorone diisocyanate to 29.3 g, and the amount of curing agent in (3) to 10.1 g, respectively, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.79, viscosity at 25°C at 100 rpm with an E-type viscometer of 188 mPa·s).

Example 11
In Example 1, the amount of cyclohexyl methacrylate in (1) was changed to 38.5 g and the amount of n-butyl acrylate was changed to 35 g, respectively, to obtain acrylic polyol D (number average molecular weight Mn 1810, hydroxyl value 120 mgKOH/g, Tg 60°C, 60 wt% solution of propylene glycol butyl ether acetate), and the acrylic polyol A in (2) was changed to the same amount of acrylic polyol D, and the amount of isophorone diisocyanate was changed to 36.3 g, respectively, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.83, viscosity at 25°C at 100 rpm with an E-type viscometer 348 mPa s).

Example 12
In Example 1, the amount of cyclohexyl methacrylate in (1) was changed to 47.5 g and the amount of n-butyl acrylate was changed to 26 g, respectively, to obtain acrylic polyol E (number average molecular weight Mn 1820, hydroxyl value 120 KOHmg/g, Tg 12°C, 60 wt% solution of propylene glycol butyl ether acetate), and the acrylic polyol A in (2) was changed to the same amount of acrylic polyol E, and the amount of isophorone diisocyanate was changed to 36.4 g, respectively, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.84, viscosity at 25°C at 100 rpm with an E-type viscometer 223 mPa s).

Example 13
In Example 1, the acrylic polyol A in (2) was changed to the same amount of acrylic polyol F (Toa Gosei product Alfon UH2041, hydroxyl value 120 mgKOH/g, Tg -55°C, 60 wt% solution of propylene glycol butyl ether acetate), and the amount of isophorone diisocyanate was changed to 36.3 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.83, viscosity at 25°C at 100 rpm with an E-type viscometer 262 mPa s).

Comparative Example 1
In Example 1, the total amount of polycarbonate polyol in (2) was changed to 70 g of polytetramethylene glycol (Mitsubishi Chemical product PTMG 2000 hydroxyl value 56.0 mg KOH/g), 2-isopropyl-3-(2-hydroxyethyl) oxazolidine was not used, the amount of isophorone diisocyanate was changed to 29.8 g, and the amount of curing agent in (3) was changed to 17.8 g, to obtain a one-liquid moisture-curable urethane resin composition (viscosity at 25°C at 100 rpm using an E-type viscometer: 288 mPa·s). The equivalent ratio of isocyanate group/oxazolidine group (NCO/OX) was 1.83.

Comparative Example 2
In Example 1, the two types of polycarbonate diols in (2) were not used, and acrylic polyol A was changed to 100 g of acrylic polyol F (Alphon UH2041), the amount of aromatic solvent was changed to 38.4 g, and the amount of isophorone diisocyanate was changed to 47.0 g. Furthermore, 66.6 g of propylene glycol butyl ether acetate was added, and the amount of curing agent in (3) was changed to 16.0 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.83, viscosity at 25°C at 100 rpm with an E-type viscometer 248 mPa s).

Comparative Example 3
In Example 1(2), the acrylic polyol A was changed to the same amount of acrylic polyol G (Toa Gosei Co., Ltd., Alfon UH2000, hydroxyl value 20 mgKOH/g, Tg -55°C, 60 wt% solution of propylene glycol butyl ether acetate) 50.0 g (equivalent to 30 g), and the amount of isophorone diisocyanate was changed to 24.6 g, to obtain a moisture-curable resin composition (NCO/Ox equivalent ratio 1.86, viscosity at 25°C at 100 rpm with an E-type viscometer 248 mPa S).

The results obtained in the above examples and comparative examples are shown in the following table.

table
Examples: Weather resistance , impact resistance
Example 1 A
〃 2 A B
〃 3 A A
4 B A
5 A C
6 B A
7 B A
8 A A
9 A B
〃 10 B A
11 A A
〃 12 B A
13 C A
Comparative Example 1 C B
〃 2 B C
〃 3D A

The one-component moisture-curable urethane resin composition of the present invention is effectively used as a sealant, adhesive, paint, topcoat material, etc., because the cured product cured by atmospheric moisture has excellent weather resistance and impact resistance.

The object of the present invention is achieved by a one-component moisture-curable urethane resin composition composed of a urethane prepolymer and oxazolidine, the urethane prepolymer being synthesized from a polycarbonate polyol (PC), a polyol composed of an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH/g and a glass transition temperature Tg of 0 to 60°C , and a polyisocyanate, and by a coating material containing this one-component moisture-curable urethane resin composition and an aromatic solvent and/or an ether solvent.

The acrylic polyol used has a hydroxyl value of 60-150 mgKOH/g and a glass transition temperature Tg of 0-60°C. The hydroxyl value of the acrylic polyol affects the viscosity of the urethane prepolymer, and as a result, affects the workability of the paint. If the hydroxyl value is less than 60 mgKOH/g, the strength and weather resistance of the coating film tend to decrease. On the other hand, if the hydroxyl value exceeds 150 mgKOH/g, the impact resistance tends to deteriorate. In addition, the viscosity of the prepolymer increases, which causes problems in prepolymer production. If the glass transition temperature Tg is less than 0°C, the impact resistance is excellent, but the weather resistance may decrease, while if it exceeds 60°C, the weather resistance is excellent, but the impact resistance may decrease.

The urethane prepolymer may also contain an oxazolidine compound in which a hydroxyl-containing oxazolidine has been reacted in advance with a polyisocyanate, preferably a compound in which a hydroxyl-containing oxazolidine (OH) has been reacted with an isocyanate group (NCO) in a ratio of NCO/OH = 1/0.1 to 1/1 . Here, an aliphatic polyisocyanate is preferably used as the polyisocyanate.

(3) Urethane prepolymer A 250.4g
Leveling agent (BYK Japan product 0.2g
BYK- UV 3576)
UV absorber (Ciba-Geigy UV1164) 5g
Light stabilizer (Ciba-Geigy product HALS292) 5g
Hardener 13.9g
[2-isopropyl-3-(2-hydroxyethyl)
2 moles of oxazolidine and hexamethylene
Adduct with 1 mole of diisocyanate;
Molecular weight 486.68]
Octyl acid 0.03g
The mixture was thoroughly stirred to obtain a transparent one-component moisture-curable urethane resin composition A (viscosity 273 mPa·s at 25°C using an E-type viscometer at 100 rpm). The equivalent ratio of isocyanate group/oxazolidine group (NCO/OX) was 1.84.

Comparative Example 1
In Example 1, the acrylic polyol A in (2) was changed to the same amount of acrylic polyol F (Toa Gosei product Alfon UH2041, hydroxyl value 120 mgKOH/g, Tg -55°C, 60 wt% solution of propylene glycol butyl ether acetate), and the amount of isophorone diisocyanate was changed to 36.3 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.83, viscosity at 25°C at 100 rpm with an E-type viscometer 262 mPa s).

Comparative Example 2
In Example 1, the total amount of polycarbonate polyol in (2) was changed to 70 g of polytetramethylene glycol (Mitsubishi Chemical product PTMG 2000 hydroxyl value 56.0 mg KOH/g), 2-isopropyl-3-(2-hydroxyethyl) oxazolidine was not used, the amount of isophorone diisocyanate was changed to 29.8 g, and the amount of curing agent in (3) was changed to 17.8 g, to obtain a one-liquid moisture-curable urethane resin composition (viscosity at 25°C at 100 rpm using an E-type viscometer: 288 mPa·s). The equivalent ratio of isocyanate group/oxazolidine group (NCO/OX) was 1.83.

Comparative Example 3
In Example 1, the two types of polycarbonate diols in (2) were not used, and acrylic polyol A was changed to 100 g of acrylic polyol F (Alphon UH2041), the amount of aromatic solvent was changed to 38.4 g, and the amount of isophorone diisocyanate was changed to 47.0 g. Furthermore, 66.6 g of propylene glycol butyl ether acetate was added, and the amount of curing agent in (3) was changed to 16.0 g, to obtain a one-component moisture-curable urethane resin composition (NCO/OX equivalent ratio 1.83, viscosity at 25°C at 100 rpm with an E-type viscometer 248 mPa s).

Comparative Example 4
In Example 1(2), the acrylic polyol A was changed to the same amount of acrylic polyol G (Toa Gosei Co., Ltd., Alfon UH2000, hydroxyl value 20 mgKOH/g, Tg -55°C, 60 wt% solution of propylene glycol butyl ether acetate) 50.0 g (equivalent to 30 g), and the amount of isophorone diisocyanate was changed to 24.6 g, to obtain a moisture-curable resin composition (NCO/Ox equivalent ratio 1.86, viscosity at 25°C at 100 rpm with an E-type viscometer 248 mPa S).

The results obtained in the above examples and comparative examples are shown in the following table.

table
Examples: Weather resistance , impact resistance
Example 1 A
〃 2 A B
〃 3 A A
4 B A
5 A C
6 B A
7 B A
8 A A
9 A B
〃 10 B A
11 A A
〃 12 B A
Comparative Example 1 C A
〃 2 C B
〃 3 B C
〃 4D A

The object of the present invention is achieved by a one-component moisture-curable urethane resin composition comprising a urethane prepolymer and an oxazolidine compound , wherein the urethane prepolymer is a urethane prepolymer having an isocyanate group at a terminal synthesized from a polyol comprising a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH/g and a glass transition temperature Tg of 0 to 60°C, and a polyisocyanate, and the total amount of PC and AC in the polyol is 80 mass% or more, and by a paint comprising this one-component moisture-curable urethane resin composition and an aromatic solvent and/or an ether solvent.

Example 1
(1) 66.7 g of propylene glycol monobutyl ether acetate was charged into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the mixture was heated to 92°C while replacing with nitrogen. Next, a mixture of 59.0 g of cyclohexyl methacrylate, 14.5 g of n-butyl acrylate, 14.0 g of 2-hydroxyethyl methacrylate, 12.5 g of 2-hydroxyethyl acrylate, and 2.9 g of tert-butylperoxy-2-ethylhexanoate was fed over 4 hours. One hour and two hours after the end of the feed, 0.2 g each of tert-butylperoxy-2-ethylhexanoate was added, and the mixture was allowed to react for another 2 hours to obtain acrylic polyol A.
(2) In a 500 ml separable flask equipped with a stirring blade, 35.0 g of dried polycarbonate diol (ETERNACOLL PH-200, hydroxyl value 56 mg KOH/g), 35.0 g of polycarbonate diol (Nipporan PC-982R, hydroxyl value 56 mg KOH/g), and 50.0 g (equivalent to 30.0 g) of acrylic polyol A (number average molecular weight Mn 1830, hydroxyl value 120 mg KOH/g, Tg 28°C, propylene glycol butyl ether acetate 60 mass% solution) were dissolved in 89.0 g of aromatic solvent (Shin Nippon Kagaku Products R100), and then 36.4 g of isophorone diisocyanate and 0.02 g of dibutyltin dilaurate were added and stirred at room temperature for 1 hour, followed by 2-isopropyl-3-(2-hydroxyethyl)oxazolidine. The mixture was gradually heated to 80° C. in a nitrogen stream and reacted at 80° C. for 2 hours to obtain 250.4 g of urethane prepolymer A.

(4) The obtained one-liquid moisture-curing urethane resin composition A was applied to a thickness of 0.3 mm on a Nichiha ceramic siding board coated with a urethane primer obtained by reacting 3.0 g of 3-aminopropyltriethoxysilane with 200.0 g of acrylic polyol (Toa Gosei product Alfon UH2041), 200.0 g of aromatic solvent (Shin-Nihon Kagaku product R100), 94.1 g of isophorone diisocyanate, and 0.3 g of dibutyltin dilaurate to a thickness of 0.15 mm, and cured and aged for 2 weeks under an environment of 23 (± 2) ° C. and 50 (± 10) % RH to obtain a paint cured product on the siding board. Weather resistance test and impact resistance test were performed using the obtained paint cured product.

[Weather resistance test]
Testing equipment: Iwasaki Electric Co., Ltd. Eye Super UV Tester Testing conditions: UV illuminance: 150±8mW/ ^cm2
Temperature: 63°C
Wavelength: 295-450nm
Cycle: 63℃±3℃, 50% RH, 4 hours of exposure ⇒ 4 hours of condensation Test result evaluation: 1600 hours no change A, 1200 hours no change B, 800 hours no change
C: Whitening or cracking occurs after 800 hours. D:

[Impact resistance test]
Test method: JIS K5600-5-3 (1999) General test method for paints, Part 5: Mechanical properties of coating film, Section 3: Resistance to falling weight, based on DuPont method
The paint was applied to a thickness of 0.3 mm on a 2 mm thick acrylic resin cut to 50 mm x 50 mm, and left to harden and cure for 2 weeks in an environment of 23 (±2) °C and 50 (±10) % RH. Next, a 6.35 mm radius shot mold and a receiving stand were attached so that the coated surface was facing up, and a 300 g weight was dropped from a height of 40 cm, 30 cm, or 20 cm, and the appearance of the coating film was observed. Test result evaluation: A: no cracks in the coating film at a height of 40 cm, B: B at 30 cm, C: C at 20 cm, and D: D: D

The object of the present invention is achieved by a one-component moisture-curable urethane resin composition comprising a urethane prepolymer and an oxazolidine compound , wherein the urethane prepolymer is a urethane prepolymer having an isocyanate group at a terminal synthesized from a polyol comprising a polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH/g and a glass transition temperature Tg of 0 to 60°C, and a polyisocyanate, and the total amount of PC and AC in the polyol is 80 mass% or more, and by a paint comprising this one-component moisture-curable urethane resin composition and an aromatic solvent and/or an ether solvent.

Example 1
(1) 66.7 g of propylene glycol monobutyl ether acetate was charged into a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen inlet tube, and the mixture was heated to 92°C while replacing with nitrogen. Next, a mixture of 59.0 g of cyclohexyl methacrylate, 14.5 g of n-butyl acrylate, 14.0 g of 2-hydroxyethyl methacrylate, 12.5 g of 2-hydroxyethyl acrylate, and 2.9 g of tert-butylperoxy-2-ethylhexanoate was fed over 4 hours. One hour and two hours after the end of the feed, 0.2 g each of tert-butylperoxy-2-ethylhexanoate was added, and the mixture was allowed to react for another 2 hours to obtain acrylic polyol A.
(2) In a 500 ml separable flask equipped with a stirring blade, 35.0 g of dried polycarbonate diol (ETERNACOLL PH-200, hydroxyl value 56 mg KOH/g), 35.0 g of polycarbonate diol (Nipporan PC-982R, hydroxyl value 56 mg KOH/g), and 50.0 g (equivalent to 30.0 g) of acrylic polyol A (number average molecular weight Mn 1830, hydroxyl value 120 mg KOH/g, Tg 28°C, propylene glycol butyl ether acetate 60 mass% solution) were dissolved in 89.0 g of aromatic solvent (Shin Nippon Kagaku Products R100), and then 36.4 g of isophorone diisocyanate and 0.02 g of dibutyltin dilaurate were added and stirred at room temperature for 1 hour, followed by 2-isopropyl-3-(2-hydroxyethyl)oxazolidine. The mixture was gradually heated to 80° C. in a nitrogen stream and reacted at 80° C. for 2 hours to obtain 250.4 g of urethane prepolymer A.

(4) The obtained one-liquid moisture-curing urethane resin composition A was applied to a thickness of 0.3 mm on a Nichiha ceramic siding board coated with a urethane primer obtained by reacting 3.0 g of 3-aminopropyltriethoxysilane with 200.0 g of acrylic polyol (Toa Gosei product Alfon UH2041), 200.0 g of aromatic solvent (Shin-Nihon Kagaku product R100), 94.1 g of isophorone diisocyanate, and 0.3 g of dibutyltin dilaurate to a thickness of 0.15 mm, and cured and aged for 2 weeks under an environment of 23 (± 2) ° C. and 50 (± 10) % RH to obtain a paint cured product on the siding board. Weather resistance test and impact resistance test were performed using the obtained paint cured product.

[Weather resistance test]
Testing equipment: Iwasaki Electric Co., Ltd. Eye Super UV Tester Testing conditions: UV illuminance: 150±8mW/ ^cm2
Temperature: 63°C
Wavelength: 295-450nm
Cycle: 63℃±3℃, 50% RH, 4 hours of exposure ⇒ 4 hours of condensation Test result evaluation: 1600 hours no change A, 1200 hours no change B, 800 hours no change
C: Whitening or cracking occurs after 800 hours. D:

[Impact resistance test]
Test method: JIS K5600-5-3 (1999) General test method for paints, Part 5: Mechanical properties of coating film, Section 3: Resistance to falling weight, based on DuPont method
The paint was applied to a thickness of 0.3 mm on a 2 mm thick piece of acrylic resin cut to 50 mm x 50 mm, and left to harden and cure for 2 weeks in an environment of 23 (±2) °C and 50 (±10) % RH. Next, a 6.35 mm radius shot mold and a receiving stand were attached so that the coated surface was facing up, and a 300 g weight was dropped from a height of 40 cm, 30 cm, or 20 cm, and the appearance of the coating film was observed. Test result evaluation: A: no cracks in the coating film at a height of 40 cm, B: B at 30 cm, C: C at 20 cm, and D: D: D

Claims (8)

A one-component moisture-curing urethane resin composition consisting of a urethane prepolymer and oxazolidine, in which the urethane prepolymer is synthesized from a polyol consisting of polycarbonate polyol (PC) and an acrylic polyol (AC) having a hydroxyl value of 60 to 150 mgKOH/g, and a polyisocyanate. The moisture-curable urethane resin composition according to claim 1, wherein the glass transition temperature Tg of AC is 0 to 60°C. The one-component moisture-curable urethane resin composition according to claim 1, in which a urethane prepolymer consisting of polycarbonate polyol, acrylic polyol and hydroxyl group-containing oxazolidine is used. The one-component moisture-curable urethane resin composition according to claim 1, wherein the polyisocyanate is an aliphatic polyisocyanate. A one-component moisture-curable urethane resin composition according to any one of claims 1 to 4, in which an oxazolidine compound in which a hydroxyl-containing oxazolidine has been reacted in advance with a polyisocyanate is blended with a urethane prepolymer. The one-component moisture-curable urethane resin composition according to claim 1 or 3, in which the mass ratio of PC/AC is 60/40 to 90/10, and the total of PC and AC in the polyol is 80 mass% or more. The one-component moisture-curable urethane resin composition according to claim 1 or 3, in which the equivalent ratio of isocyanate groups (NCO) to oxazolidine groups (OX) in the composition is NCO/OX = 1.5 to 3.0. A coating material comprising the one-component moisture-curable urethane resin composition according to claim 1 or 3 and an aromatic solvent and/or an ether solvent.