JP3316886B2 - Urethane resin composition and paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a urethane resin composition and a paint using the same.

[0002]

2. Description of the Related Art Acrylic urethane resin coatings using resins obtained by reacting acrylic polyols and polyisocyanates cure at low temperatures and have excellent chemical resistance, solvent resistance, weather resistance, etc. It is used for applications that cannot be processed at high temperatures, such as for building materials such as plastic, paper, concrete, and other large structures. However, since a large amount of solvent evaporates into the air after being coated on the object, there is a problem in terms of resource saving and low pollution.

[0003] To solve this problem, Japanese Patent Laid-Open No. 4-1 is disclosed.
No. 17418 proposes a method of reducing the volatilization of a solvent by combining a low molecular weight polyol as a reactive diluent with an acrylic polyol and a polyisocyanate. However, in this method, volatility is improved, but there is still room for improvement in curability.

On the other hand, Japanese Patent Application Laid-Open No. 61-151223 discloses a method of obtaining a polymer by reacting a mixture of a bicyclic amide acetal, a low molecular weight polyol and a polyisocyanate in a molding machine. Since it is difficult to control the properties, the pot life is short, and there are problems such as foaming and heat generation. No application of this polymer to a paint has been suggested.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and provides a urethane-based resin composition which hardly volatilizes during solvent coating, has excellent curability, and can be cured at room temperature or at low temperature. A paint using the same is provided.

[0006]

That is, the present invention relates to (A) a vinyl copolymer having a hydroxyl group, (B) a polyisocyanate and (C) a bicyclic amide acetal comprising 5 to 9 carbon atoms.
9% of 5% by weight and polyol (excluding component (A))
The present invention relates to a urethane-based resin composition containing a reactive diluent consisting of 5 to 5% by weight, and a paint containing the same.

The hydroxyl group-containing vinyl copolymer (A) used in the present invention can be obtained by copolymerizing a hydroxyl group-containing vinyl monomer with another copolymerizable vinyl monomer. .

The vinyl monomers having a hydroxyl group include:
For example, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, 5
-Hydroxyalkyl acrylates such as hydroxypentyl acrylate, or methacrylates having a similar hydroxyalkyl group, further glycerin, monoacrylates or monomethacrylates of polyhydric alcohols such as trimethylolpropane, N-methylolacrylamide, N-methylolmethacrylamide and the like, Further, there are compounds obtained by ring-opening addition of ε-caprolactone to these.

The vinyl monomer having a hydroxyl group is preferably blended so that the copolymer (A) has a hydroxyl value of 20 to 200. When the hydroxyl value is less than 20, urethane bonds formed later are small, and curability, chemical resistance,
A decrease in solvent resistance and the like is likely to occur. On the other hand, when it exceeds 200, a large amount of isocyanate described later is required, and the pot life tends to be short.

Other vinyl monomers constituting the copolymer of component (A) include methyl acrylate,
Cyanation of alkyl or cycloalkyl acrylate such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, stearyl acrylate, cyclohexyl acrylate or similar methacrylate, acrylonitrile, methacrylonitrile, etc. Vinyl esters of saturated monobasic acids such as vinyl, vinyl acetate, vinyl propionate and vinyl stearate, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, octyl vinyl ether, lauryl vinyl ether and phenyl vinyl ether; amides such as acrylamide and methacrylamide Group-containing unsaturated monomer, styrene or vinyl toluene, α- Styrene, substituted styrenes such as chlorostyrene, tricyclodecyl-α-chloroacrylate, acrylates of hydrogenated dicyclopentadiene derivatives such as tricyclodecylethyl acrylate or similar methacrylates, and further, if necessary, acrylic acid, methacrylic acid, etc. Phosphate group-containing acrylates such as unsaturated monobasic acid, ethylene phosphate acrylate, trimethylene phosphate phosphate, 1-chloromethylethylene acrylate phosphate or similar phosphate group-containing methacrylates, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, etc. And an epoxy group-containing unsaturated monomer such as amino group-containing acrylate or similar amino group-containing methacrylate, glycidyl acrylate and glycidyl methacrylate.

A copolymer of the component (A) can be obtained by blending one or more of these monomers and polymerizing them. The polymerization can be carried out by a known method such as a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, a bulk polymerization method, etc., but the solution polymerization method is industrially preferable. Furthermore, when finally reacting with a polyisocyanate as in the present composition, an organic solvent containing no hydroxyl group such as toluene, xylene, butyl acetate, ethyl acetate, methyl ethyl ketone, and methyl isobutyl ketone is usually used as a reaction solvent. In the case of the present invention, it is most industrially preferable to use the polyol (C), which will be described in detail later, as a reaction solvent. Here, the polymerization initiator is not particularly limited, and a known radical polymerization initiator can be used. For example, benzoyl peroxide,
Examples include peroxide radical initiators such as di-tert-butyl peroxide and azo radical initiators such as azobisisobutylnitrile and azobisvaleronitrile. If necessary, a molecular weight modifier such as mercaptan, carbon tetrachloride, carbon tetrabromide and the like can be used.

The weight average molecular weight of the copolymer thus obtained is preferably from 2,000 to 20,000. Where 2
When the molecular weight is less than 000, the curability and durability of the cured film are poor. On the other hand, when it exceeds 20,000, the solubility in a reactive diluent, the appearance of the film and the workability of the film are poor. In addition, the weight average molecular weight in this specification is a value measured by gel permeation chromatography and converted using a calibration curve of standard polystyrene.

The urethane resin composition of the present invention further contains a polyisocyanate as the component (B). Examples of the polyisocyanate include aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, methylcyclohexane diisocyanate, and isopropylidene bis (4-cyclohexyl isocyanate). Aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenylmethane diisocyanate; Compounds having two or more isocyanate groups such as burettes and isocyanurates to which the diisocyanates are added; Diisocyanates and low molecular polyols Produced by the reaction with
There are compounds in which two or more isocyanate groups remain. Here, as the low molecular polyols, the same low molecular polyols as those used in the component (C) described later can be used.

The reactive diluent of the component (C) comprises 5 to 95% by weight of the bicyclic amide acetal and 95 to 5% of the polyol.
% By weight. When the amount of the bicyclic amide acetal is less than 5% by weight, the curability is inferior. Even if the curability is improved by using an accelerated catalyst or the like, the pot life becomes shorter. Conversely, when the content of the low-molecular polyol is less than 5% by weight, it becomes difficult to obtain the component (A) by an industrially preferable method as described above. Most preferably, the bicyclic amide acetal is from 20 to 80% by weight.

Here, the bicyclic amide acetal preferably has the following structural formula.

Embedded image (Wherein, R represents a hydrocarbon group having 1 to 18 carbon atoms, R ¹ can be independently selected, and hydrogen, carbon atom 1
Hydrocarbon groups having -18, or 2-18 carbon atoms
R ² represents hydrogen, a hydrocarbon group having 1 to 18 carbon atoms and an ether group having 1 to 18 carbon atoms. In particular, 5-methyl-4,6-dioxa-1-azabicyclo [3.3.0] octane (in the above general formula, R
Is a methyl group, and R ¹ and R ² are hydrogen).

The polyol as the component (C) is not particularly limited. For example, ethylene glycol, diethylene glycol, triethylene glycol, pentaethylene glycol, polyethylene glycol, 1,4-butanediol, propylene glycol, dipropylene glycol, tripropylene Glycol, polypropylene glycol, 2,2-dimethyl-1,3-propanediol,
2-methyl-1,3-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 2-methyl-1,3-pentanediol, 1,2-cyclohexanediol, 1,4-cyclohexanediol, 1,2-
Bis (hydroxymethyl) cyclohexane, 2,2-diethylpropanediol-1,3,2,2-diethylbutanediol-1,3, butene-2-diol-1,
4, trimethylolpropane, trimethylolethane,
Glycerol, 1,2-4-butanetriol, 1,
2,6-hexanetriol, erythritol, D-threitol, L-threitol, sorbitol, D-mannitol, dichryserol, ethiterdiol 204
(2,2-dimethyl-3-hydroxypropyl 2,2-
Dimethyl-3-hydroxypropionate), 1,4-
Aliphatic polyhydric alcohols such as cyclohexane dimethanol, xylene alcohol, ethyl resorcinol, propyl resorcinol, 2,4-dimethyl resorcinol, 3,6-dimethyl-1,2,4-benzenetriol, ethyl pyrogallol, 2, 4-dimethyl-1,4-
Dihydroxynaphthalene, 3-methyl-1,4,5-naphthalenetriol, dimethyloltoluene, dimethylolxylene, resorcinol, bishydroxyethyl or bishydroxypropylether of catechol or hydroquinone, 1,5-dihydroxynaphthalene,
There are aromatic polyhydric alcohols such as 4,4-isopropylidene-bisphenol. Further, a compound having at least two hydroxyl groups per molecule generated from these substances and other substances and having an equivalent weight in the range of 200 to 5,000 can also be used. For example, by homopolymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide, or epichlorohydrin, or ethylene glycol, propylene glycol, trimethylolpropane,
Also included are polyether polyols, urethane diols, polyester polyols, polythioether polyols, polyacetal polyols, polycarbonate polyols, polyester amide polyols and the like, which are formed by addition to 4,4'-dihydroxyldiphenylpropane. However, when used as component (C), component (A)
It is preferable that the component and the component (B) have excellent dilutability, and a polyol having a hydroxyl equivalent of 2000 or less is more preferable.
Tripropylene glycol, polyethylene glycol having a hydroxyl equivalent of 500 or less, polypropylene glycol,
Polyester diol and the like are most preferred.

The vinyl copolymer of the component (A) and the reactive diluent of the component (C) are used in an amount of 1/2 to 5 in terms of the former / latter weight ratio.
/ 1 is preferably contained. This ratio is 1
If it is less than / 2, the curability and cracking properties of the coating film tend to be inferior, while if it exceeds 5/1, the viscosity of the solution tends to be too high and the coating workability tends to be inferior.

The proportions of the copolymer of the component (A), the reactive diluent of the component (C) and the polyisocyanate of the component (B) are as follows: hydroxyl groups in the components (A) and (C); The equivalent ratio of the sum of hydroxyl groups / isocyanate group calculated as two hydroxyl groups when one molecule of the cyclic amide acetal reacts with water to form the corresponding amide diol is 1/3 to 1/1. It is preferable to mix them. If the equivalent ratio is less than 1/3, the amount of unreacted polyisocyanate tends to increase and the properties of the coating film tend to decrease, while if it exceeds 1/1, the reactive diluent volatilizes and the coating film appearance. And the gasoline resistance tends to decrease.

In the present invention, it is preferable that the polyisocyanate of the component (B) is a two-pack type which is mixed immediately before use. When the thus obtained urethane-based resin composition of the present invention is used as a paint, pigments, dyes, ultraviolet absorbers, light stabilizers, various additives and various solvents such as a surface conditioner used in general paints are used. Can be blended. If necessary, a urethanization-promoting catalyst such as an organic metal salt such as a tertiary amine or dibutyltin dilaurate generally used in polyurethane technology is used as the component (A) and the component (C).
It can also be blended with the components and uniformly mixed.

The paint of the present invention can be used for wood, paper, plastic,
It may be applied directly to materials such as concrete and various metals, or may be used in combination with one or more of ordinary coating systems (primer, intermediate coating, top coating) on these materials.

The paint of the present invention can be applied by any method such as brush coating, dipping, spray coating, roll coating, flow coater coating, shibori (shigoki) coating, and knife coater coating.

[0022]

In the urethane resin composition of the present invention,
The reactive diluent of the component (C) functions as a diluent when applying a mixture of the hydroxyl group-containing vinyl copolymer of the component (A) and the polyisocyanate of the component (B), and at the same time, ( At the time of the curing reaction of the component (A) and the component (B), the component (C) also participates in the reaction and is incorporated into a part of the cured coating film component, and does not volatilize in the air unlike a general organic solvent.

Although the exact mechanism of the reaction of the bicyclic amide acetal in the component (C) is not known, it is supposed that the bicyclic amide acetal reacts with the moisture in the air to form a coating film. It is thought that the corresponding amide diol is formed, and then this amide diol reacts with the isocyanate group and acts as an accelerator for the reaction between the hydroxyl group and the isocyanate group of the components (A) and (B). It is considered that the above reaction mechanism acts to improve the curability of the coating film without impairing the pot life.

[0024]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto.

Examples 1 to 3 and Comparative Examples 1 to 3 (1) Synthesis Examples 1 to 4 Production of Copolymers Four ports equipped with a stirrer, thermometer, nitrogen gas blowing tube, reflux cooling tube and dropping funnel The solvent shown in Table 1 was charged into the flask, and a mixture obtained by dissolving the polymerization catalyst in the monomer mixture having the composition shown in Table 1 was added dropwise over 2 hours while keeping the flask at 140 to 150 ° C. Hold for 2 hours. Table 1 shows the properties of the obtained copolymer solution.

[0026]

[Table 1] * Measured without solvent (tripropylene glycol or xylene).

(2) Preparation and coating of paint The copolymer solution, solvent and polyisocyanate obtained in (1) above (polymethyl polyphenyl isocyanate manufactured by Sumitomo Bayer Urethane Co., Ltd., isocyanate group content about 31% by weight, Trade name: Sumidur 44V-20) and a urethanization reaction catalyst were blended in the proportions shown in Table 2 to obtain a paint.

The obtained paint was applied to a steel plate substrate by using a bar coater # 4.
And dried at 60 ° C. for 10 minutes. The properties of the paint and the performance of the coating film were determined by the following methods, and the results are shown in Table 2.

(A) Application Solid The weight of a steel sheet substrate is x, the weight immediately after coating is y, the weight after drying and curing is Z, and application solid = Z−x / y−x × 100
(%).

(B) Pot life 100 g of the coating material was sealed in a round can, left at 20 ° C., and indicated by the time until gelling. (C) Curability Pencil hardness was evaluated in a room at 23 ° C. according to JIS K5400.

[0031]

[Table 2]

[0032]

The urethane-based resin composition and paint of the present invention have low pollution and excellent work hygiene, and have excellent curability because they have little volatilization of the solvent. It can be cured at low temperatures and has a sufficient pot life.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08G 18/00-18/87 C09D 175/00-175/12

Claims (7)

(57) [Claims] (A) a vinyl copolymer having a hydroxyl group,
A coating composition containing a reactive diluent comprising (B) 5 to 95% by weight of a polyisocyanate and (C) a bicyclic amide acetal and 95 to 5% by weight of a polyol (excluding the component (A)). Urethane resin composition for use . 2. The weight average molecular weight of the vinyl copolymer (A) is 2,000 to 20,000, and the hydroxyl value is 20 to 20.
The urethane-based resin composition for a paint according to claim 1, which is 0. 3. The urethane resin composition for a coating according to claim 1, wherein the copolymer of the component (A) is obtained by a solution polymerization method using the polyol in the component (C) as a solvent. . (4) The bicyclic amide acetal of the component (C) contains 5
-Methyl-4,6-dioxa-1-azabicyclo [3.
3.0] The paint according to claim 1, 2 or 3, which is octane.
Urethane resin composition for use . 5. The compounding ratio of the vinyl copolymer (A) and the reactive diluent (C) is 1/2 to 5/1 by weight of the former / the latter. The mixing ratio of the polyisocyanate of the component (B) to the total of the components (A) and (C) is such that the hydroxyl groups in the components (A) and (C) and 2
The equivalent ratio of the sum of hydroxyl groups / isocyanate groups when the cyclic amide acetal reacts with water to form the corresponding amide diol is 1/3 to 1/1.
The urethane-based resin composition for a coating according to 2, 3, or 4. 6. A paint comprising the urethane resin composition for a paint according to claim 1, 2, 3, 4, or 5. 7. (A) a vinyl copolymer having a hydroxyl group,
(B) polyisocyanate and (C ) bicyclic amide ace
5 to 95% by weight of tar and polyol (provided that (A)
% Of the reactive diluent).
A urethane-based resin composition having the component (A)
The polymer uses the polyol in the component (C) as a solvent.
Urethane resin obtained by a solution polymerization method
Composition.