JPH06287512A - Polyurethane coating material made by using specified curing agent based on polyisocyanate - Google Patents

Abstract

PURPOSE:To obtain a coating material excellent in heat resistance, weatherability, curability, adhesiveness, stain resistance and abrasion resistance, by using a specified curing agent and a specified polyol as the constituents. CONSTITUTION:This coating material is obtained by using as the constituents: a curing agent consisting of an isocyanuratemodified hexamethylene diisocyanate which has a urethane linkage and an isocyanurate ring structure and is prepared by reacting hexamethylene diisocyanate and a di- or trifunctional polyol (e.g. 1,3-butanediol) in the presence of a trimerization catalyst (e.g. potassium caprate), and an NCO-terminated prepolymer (e.g. a prepolymer obtained from diphenylmethane diisocyanate and diethylene glycol); and a polyol (e.g. polyester polyol) having a molecular weight of 500 or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane paint using a specific polyisocyanate curing agent, and more specifically, it uses a specific polyisocyanate curing agent useful for any object such as metal, plastic and wood. It relates to polyurethane paint.

[0002]

2. Description of the Related Art It is well known that polyurethane derived from hexamethylene diisocyanate (hereinafter referred to as HDI) has excellent weather resistance due to its characteristics. Therefore, a polyol adduct of HDI or a modified product by buret bond is used as a polyisocyanate curing agent for paints. However, both the polyol adduct and the modified product due to the buret bond are likely to be decomposed and deteriorated by heating, and the weather resistance is limited. Further, the HDI-based compound has a slow reaction with the active hydrogen compound, so that in order to increase the crosslink density and obtain excellent durability, it is necessary to rely on baking and drying. On the other hand, aromatic diisocyanates are superior to aliphatic diisocyanates such as HDI in decomposition and deterioration due to heating, but aromatic diisocyanates are not suitable as weather resistant paints because they yellow due to light. However, the reactivity is faster than that of the HDI system and there is no limitation as seen in the HDI system even under the baking condition. Therefore, isocyanates having weather resistance, heat resistance, and curability are desired.

[0003]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventors of the present invention have conducted extensive studies to improve the conventional problems, and as a result,
The inventors have found that the improvement can be achieved by using a modified form of HDI (A) having a urethane bond and an isocyanurate ring structure in I and an NCO group-terminated prepolymer (B) in combination to achieve the present invention.

[0004]

Means for Solving the Problems That is, the present invention is directed to a urethane bond and an isocyanate obtained by reacting in the presence of hexamethylene diisocyanate, a polyol (d) having a molecular weight of 62 to 3000 and a functional number of 2 to 3, and a trimerization catalyst. A polyurethane coating characterized by using a curing agent comprising a modified isocyanurate of hexamethylene diisocyanate having a nurate ring structure (A) and an NCO group-terminated prepolymer (B) and a polyol (C) having a molecular weight of 500 or more. is there.

The polyisocyanate curing agent of the present invention contains H
A modified isocyanurate of HDI having a urethane bond and an isocyanurate ring structure in the molecule obtained by reacting in the presence of DI, a polyol (d) and a trimerization catalyst (hereinafter referred to as a modified HDI (A)) and NCO. It is composed of a group-terminated prepolymer (B). In the modified HDI (A), a part (15% by weight or less) of all NCO groups before the reaction of HDI has a urethane bond.

The polyol (d) has a molecular weight of 62-
It has 3000 functional groups and 2 to 3 functional groups. Bifunctional polyols include, for example, ethylene glycol, diethylene glycol (DEG), 1,3-butanediol (1,3
-BD), 1,4-butanediol (1,4-BD),
Propylene glycol, dipropylene glycol, neopentyl glycol, 1,6-hexanediol (1,
6-HD), 3-methyl-1,5-pentanediol,
Examples include diols such as 2,2′-diethyl-1,3-propanediol and butylethylpropanediol, divalent polyester polyols, and polyether polyols.

Examples of trifunctional polyols include triols such as glycerin, trimethylolethane, and trimethylolpropane (TMP), and trivalent polyether polyols. Further, bifunctional or higher functional polyester polyols may be mentioned. These polyols can be used alone or as a mixture of two or more. The preferred molecular weight of these polyols is 62-2000.

The urethane bond in the modified HDI (A) is
It is preferably 15% by weight or less based on all the isocyanate groups before the start of the reaction. If it is 15% by weight or more, the features of the isocyanurate-forming bond produced thereafter cannot be sufficiently exhibited. More preferably, it is 10% by weight or less.

The catalyst used to obtain the modified HDI (A) is a potassium or sodium salt of an organic acid represented by the general formula CnH _{2n + 1} COOH, which may be used alone or in combination, and may be used as a co-catalyst. Can also be used together, and the reaction can be carried out at 100 ° C. or lower. As a catalyst that can be used,
Examples thereof include propionic acid, butyric acid, valeric acid, caproic acid, heptanoic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, and potassium or sodium salts of these branched fatty acids.

If a phenolic hydroxy compound, an alcoholic hydroxy compound, or a tertiary amine is used as a cocatalyst at the same time as these catalysts, the reaction proceeds more easily. In such a urethanization and isocyanurate-forming reaction of HDI, the progress of the reaction can be known by measuring the NCO content during the reaction. The NCO content of the HDI modified product (A) is 16.5 to 23.5% by weight.

NCO group-terminated prepolymer (B) of the present invention
Aromatic, aliphatic, alicyclic and the like are used as the polyisocyanate for obtaining the above. Examples of aromatic polyisocyanates include 2,4- or 2,6-tolylene diisocyanate, naphthylene-1,5-diisocyanate, 4,4 ′, 4 ″ -triisocyanatotriphenylmethane, 2,4,6. -Triisocyanatotoluene, or polyphenylene polymethylene polyisocyanate (polymeric MDI), diphenylmethane diisocyanate (MDI), etc., such as those produced by aniline-formaldehyde condensation and subsequent phosgenation, and as the aliphatic or alicyclic polyisocyanate, , For example, tetramethylene diisocyanate, decamethylene diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, 1-isocyanato-3,3,5-trimethyl- -
Isocyanatomethylcyclohexane (IPDI), perhydro-2,4- and / or -2,6-diisocyanatotoluene or perhydro-2,4'- and / or -4,
4'-diisocyanatodiphenylmethane, 2-methylpentanemethylene diisocyanate, HDI and the like.

Preferred NCO-terminated prepolymer (B)
Is a prepolymer using an aromatic polyisocyanate, particularly preferably 2,2'-MDI, 2,4 '.
-MDI, 4,4'-MDI, polymeric MDI, etc., alone or in any mixture, or a part of these isocyanates modified into burette, allophanate, carbodiimide, oxazolidone, amide, imide, etc. and an active hydrogen group-containing compound Is obtained by reacting with an excess of isocyanate groups. The NCO content of such prepolymer is 16.0 to 30.0% by weight.
Is preferred.

As the compound having an active hydrogen group for obtaining the NCO group-terminated prepolymer (B), a low molecular weight polyol having a molecular weight of 62 to 500, preferably a molecular weight of 6 is used.
2 to 300. Further, the molecular weight of polyether polyol, polyester polyol, castor oil-based polyol, etc. is 300 to 5000, preferably 500 to 3000.
The following are listed. These can be used alone or as a mixture of two or more kinds. As the low molecular weight polyol, ethylene glycol, DEG, propylene glycol, 1,3-BD, 1,4-BD, 1,6-HD,
Examples include dipropylene glycol, glycerin, TMP, hexanetriol, tripropylene glycol, pentaerythritol, sorbitol, sucrose and the like. Examples of other polyols include polyethylene glycol, polypropylene glycol, poly (butylene adipate) polyol, poly (ethylene adipate) polyol, and poly (hexamethylene carbonate) polyol. In this case, when the isocyanate is solid at room temperature, a stable prepolymer which is liquid at room temperature can be obtained by using propylene glycols to form a prepolymer.

The polyisocyanate curing agent of the present invention comprises H
The DI modified product (A) and the NCO group-terminated prepolymer (B) can be arbitrarily mixed and used within the range of 10 to 90% by weight: 90 to 10% by weight.

A molecular weight of 50 which can be used in the present invention
As the polyol (C) having 0 or more, there are polyester polyol, polyether polyol, polycarbonate polyol, acrylic polyol and the like, and as the polyester polyol, those having a molecular weight of 500 to 9000 are exemplified, for example, ethylene glycol, DEG, triethylene glycol, 1 , 2-propylene glycol, trimethylene glycol, 1,3-BD, 1,4-BD, 1,6-
HD, decamethylene glycol, glycerin, TMP,
One or more monomolecular compounds having two or more hydroxyl groups such as pentaerythritol and sorbitol, and adipic acid, succinic acid, malonic acid, maleic acid, tartaric acid, sebacic acid, phthalic acid, terephthalic acid, isophthalic acid , A monomolecular compound having two carboxyl groups such as trimellitic acid, or a compound obtained by a condensation reaction with one or more kinds of castor oil fatty acid and ring-opening such as ε-caprolactone and methyl-δ-valerolactone. A lactone ester produced by polymerization is used.

The polyether polyol has a molecular weight of 500 to 5,000, for example, glycols such as ethylene glycol, DEG, propylene glycol and dipropylene glycol, and polyols such as glycerin, trimethylolethane, TMP and pentaerythritol. Examples thereof include hydroxyl group-containing polyether polyols obtained by additionally polymerizing alkylene oxides such as oxides and propylene oxides.

The polycarbonate polyol has a molecular weight of 500 to 3,000, for example, a dealcoholization condensation reaction of glycols with a dialkyl carbonate such as dimethyl or diethyl, a dephenol condensation reaction of glycols with diphenyl carbonate, or a glycols with ethylene. Examples thereof include those obtained by deethylene glycol condensation reaction of carbonate. Examples of the glycols include 1,6-HD, DEG, propylene glycol, 1,4-BD, 3-methyl-1,5.
Examples thereof include aliphatic diols such as pentanediol and NPG, and alicyclic diols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol.

The acrylic polyol has a molecular weight of 50.
For example, hydroxyalkyl acrylate is used as a hydroxyl source, and alkyl acrylate and a compound that can be copolymerized therewith are combined and copolymerized. As the hydroxyalkyl alkylate, 2-hydroxyethyl acrylate,
There are 2-hydroxypropyl acrylate, hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, hydroxybutyl methacrylate and the like, and the alkyl acrylate has an alkyl group having 2 to 16 carbon atoms, such as ethyl acrylate. Butyl acrylate, 2-
Ethylhexyl acrylate, methyl methacrylate,
There are ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate and the like. In addition, examples of the copolymerizable compound include styrene, dibutyl fumarate, dibutyl malate, and allyl alcohol. When the molecular weight of the polyol is less than 500, the coating film becomes extremely hard and brittle, and is not suitable as a paint. When the molecular weight exceeds 100,000 and becomes large, the viscosity becomes high and the workability becomes poor, and the coating film becomes too soft and is not suitable as a coating material.

In the polyurethane coating material of the present invention, the HDI modified product (A), the NCO group-terminated prepolymer (B) and the polyol (C) are NCO / OH (molar ratio) = 0.8-1.
The solvent obtained by blending 2 can be a solvent commonly used in this field, and examples thereof are as follows. That is, toluene, xylene, ethyl acetate, butyl acetate, cello acetate, methyl ethyl ketone and the like can be mentioned. If necessary, other components such as a pigment,
Plasticizers, leveling agents, surfactants and other fillers, additives and the like can be used in combination. For oil modification, dry oil such as castor oil is used.
Various coating auxiliary materials such as a catalyst such as an organic metal salt, a filler, a flow improver, a drying modifier, and a matting agent can be used.

Since the paint according to the present invention is excellent in heat resistance and weather resistance, it can sufficiently exhibit its performance as a weather resistant paint without adding an antioxidant, an ultraviolet absorber or the like. The paint formulated as described above, for example,
Any of commonly used coating methods such as spraying, brush coating, dipping, flow coating, roll and knife coating can be applied, and curing may be performed at room temperature or by heating, although the conditions vary depending on the substrate. Further, if necessary, a catalyst can be added to accelerate curing. Since the coating material obtained by the present invention has excellent heat resistance and weather resistance, it can be widely applied to various base materials such as various metals, plastics, leathers, glasses and woods. Also,
The specific polyisocyanate curing agent of the present invention accelerates curing not only for paints, but also as an adhesive resin, a synthetic leather resin, a fiber resin, and a magnetic recording medium resin by applying it as a curing agent. Further, it is possible to improve and improve all physical properties such as heat resistance, abrasion resistance and chemical resistance of the obtained cured product.

[0021]

EXAMPLES The present invention will be described more specifically below with reference to Examples and Comparative Examples. However, the present invention is not limited to these. All "parts" and "%" in Examples and Comparative Examples are "parts by weight" and "% by weight" unless otherwise specified.

Production of modified HDI (A) Production of A-1 300 parts of HDI and polyol (d) were placed in a 500 ml separable flask equipped with a thermometer, a stirrer and a nitrogen seal tube.
1,3-BD 2.4 parts, potassium caprate 0.06 parts as a catalyst, and phenol 0.3 parts as a co-catalyst were added, the air in the flask was replaced with nitrogen, and the reaction temperature was raised to 70 ° C with stirring. The mixture was heated and reacted at the same temperature for 4 hours. To this reaction solution, 0.042 parts of phosphoric acid was added as a terminating agent, and the mixture was stirred at the reaction temperature for 1 hour, and then free HDI was removed by a molecular distillation apparatus. The obtained liquid is a pale yellow transparent liquid with an NCO content of 20.8% and a viscosity of 2200 mPa · s / 25.
C., free HDI content 0.3%. This modified product is A
-1.

Manufacture of A-2 Using the same apparatus as A-1, 300 parts of HDI, 1, 3
The reaction was performed in the same manner as in A-1 using 10.2 parts of BD, 0.06 parts of potassium propionate as a catalyst, 0.3 parts of phenol, and 0.072 parts of phosphoric acid. After distillation, NCO
The content was 19.1%, the viscosity was 2800 mPa · s / 25 ° C., and the free HDI content was 0.3%. This modified product is designated as A-2.

Manufacture of A-3 Using the same apparatus as A-2, HDI 300 parts, 1,6
-HD 3.3 parts, sodium undecylate 0.03
And 0.198 parts of phosphoric acid, the reaction was carried out in the same manner as in A-2. After distillation, NCO content 20.3%, viscosity 300
The free HDI content was 0.2% at 0 mPa · s / 25 ° C. This modified product is designated as A-3.

Production of A-4 (for Comparative Example) Using the same apparatus as A-3, 300 parts of HDI and 60 parts of trimethylolpropane were reacted at 80 ° C. for 5 hours to give an NCO content of 26.0% and a viscosity. 69000 mPa · s / 2
A 5 ° C. prepolymer was obtained. This prepolymer was designated as A-4
And

Manufacture of NCO group terminated prepolymer (B) Manufacture of B-1 MDI (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Millionate MT) 318 was prepared using the same apparatus as used for the modified product manufacture (A).
Part and 15 parts of DEG are reacted at 80 ° C. for 4 hours to obtain NCO
A prepolymer having a content of 28.0% and a viscosity of 80 mPa · s was obtained. This prepolymer is designated as B-1.

Preparation of B-2 Carbodiimide-modified MDI was prepared using the same equipment as B-1.
(Nippon Polyurethane Industry, trade name Millionate MT
L) 233 parts and PPG-2000 (Asahi Denka Kogyo polyether) 115 parts were reacted at 80 ° C. for 4 hours to obtain NCO.
A prepolymer having a content of 18.0% and a viscosity of 800 mPa · s / 25 ° C. was obtained. This prepolymer is designated as B-2.

Production of B-3 Using the same apparatus as B-1, 319 parts of MDI (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name Millionate MT) and 1,3-
BD 7 parts and dipropylene glycol 12 parts were reacted at 80 ° C. for 4 hours to give an NCO content of 27.5% and a viscosity of 150 m.
A prepolymer of Pa · s / 25 ° C. was obtained. This prepolymer is designated as B-3.

Examples 1 to 8 and Comparative Examples 1 to 4 Preparation of paint and coating film test Paints were prepared at the ratios shown in Table 1. The heat resistance of this paint,
Weather resistance and curability were measured by the following test methods. The results are shown in Table 2. Heat resistance: Apply this paint to release paper and keep it at 20 ℃, 65
The film was allowed to stand for 1 week in an environment of% RH to obtain a film having a dry film thickness of 100μ. And the film is JIS K 6
In accordance with No. 301, punching test pieces were prepared with a No. 4 dumbbell. The film 50 ° C., the film properties of each elapsed time under the conditions of 0.99 ° C., a tensile strength (T _B), was measured retention of elongation (E _B) (%) of.

Weather resistance: Steel sheet obtained by degreasing the above paint with trichlorethylene (JIS G 3141 <SPCC-
SB>, specifications: PF-1077, manufactured by Nippon Test Panel Industry Co., Ltd .; Bonde steel plate) and left for 1 week in an environment of 20 ° C. and 65% RH to form a coating film having a dry film thickness of 40 to 50 μm. It was Then, with a sunshine weatherometer (manufactured by Suga Test Instruments Co., Ltd.), black panel temperature = 63 ± 3 ° C., spraying time = 120 minutes, and JIS K 5
Gloss retention (%) after 2,000 hours according to 400,
The degree of color change (ΔE) was measured. Curability: Cut a film prepared by the same method as the heat resistance test into small pieces, put it in a Soxhlet extraction device, use acetone as the extraction solvent, and perform extraction operation with acetone under reflux at its boiling point (56 ° C) for 4 hours. I did. Then, the gel fraction value (%) was determined by the following formula.

[0031]

[Table 1]

Note in Table 1 1) Polyester polyol manufactured by Nippon Polyurethane Industry 2) Acrylic polyol manufactured by Dainippon Ink & Chemicals Co., Ltd .; solvent (toluene: ethyl acetate: butyl acetate: cellosolve acetate acetate = 1: 1: 1: 1) Resin content 3
It was set to 5%.

[0033]

[Table 2]

Examples 9 to 16 and Comparative Examples 5 to 7 A coating material was prepared in the same manner as in Example 1 and a coating film test was conducted. The paints are shown in Table 3. The coating film test results are shown in Table 4.

[0035]

[Table 3]

Note in Table 3 1) Polyester polyol manufactured by Nippon Polyurethane Industry 2) Acrylic polyol manufactured by Dainippon Ink and Chemicals Incorporated with a solvent (toluene: ethyl acetate: butyl acetate: cellosolve acetate acetate = 1: 1: 1: 1) Was 35%.

[0037]

[Table 4]

Examples 17 to 21, Comparative Examples 8 and 9 Preparation of Paint and Coating Film Test Paints were prepared in the proportions shown in Table 5. Then, using a bar coater, the polyvinyl chloride flooring material was applied so that the dry film thickness was 100 μ, and after forced drying at 80 ° C. for 20 minutes, it was applied at room temperature for 15 minutes.
After curing for a period of time, a coating film test was conducted. The results are shown in Table 5. Adhesion test: According to JIS K 5400. Stain resistance: Magic ink was applied to the surface of the coating film, and after 5 minutes, it was wiped off with a cloth impregnated with butanol. ○ Good △ Poor × Poor Abrasion resistance: According to JIS K5400 (Taber test method). Worn wheel CS-17, load 1000g

[0039]

[Table 5]

Note in Table 5 1) Castor oil-based polyester polyol, acid value 2, hydroxyl value 74, molecular weight 2040 (castor oil 545 parts, diethylene glycol 140 parts, 1,4-butanediol 15)
7 parts and 446 parts of adipic acid were obtained by an esterification reaction. ) The coating composition was diluted with a solvent in the same manner as in Example 1 to make the resin content 35%.

Examples 22 to 24 Preparation of coating materials and coating film tests were carried out in the same manner as in Example 1. The coating materials are shown in Table 6 and the coating film test results are shown in Table 7.

[0042]

[Table 6]

[0043]

[Table 7]

EFFECT OF THE INVENTION As a curing agent, a part of the NCO group of HDI is urethane-bonded with a polyol, and at the same time, a component composed of a modified isocyanurate-modified HDI and an NCO group-terminated prepolymer is used as a curing agent. As a result, excellent performance with good mutual balance in heat resistance, weather resistance, curability and the like is exhibited. It also has excellent physical properties in terms of adhesion, stain resistance, wear resistance and the like.

Claims (2)

[Claims] 1. Hexamethylene diisocyanate, polyol (d) having a molecular weight of 62 to 3000 and a functional number of 2 to 3.
And an isocyanurate modified product (A) of hexamethylene diisocyanate having a urethane bond and an isocyanurate ring structure obtained by reacting in the presence of a trimerization catalyst and NC
A polyurethane coating material comprising a curing agent composed of an O group-terminated prepolymer (B) and a polyol (C) having a molecular weight of 500 or more. 2. A polyurethane coating material, wherein the polyol (C) according to claim 1 is one or more of polyester polyols, polyether polyols, polycarbonate polyols and acrylic polyols having a molecular weight of 500 to 9000.