JP3985265B2 - Method for producing polyisocyanate for paint - Google Patents

Description

【００３６】
製造例１
攪拌機、温度計、冷却器及び窒素ガス導入管のついた容量：１Ｌの反応器に、酢酸ブチルを３００ｇ、ＴＤＩ−１００を４７４ｇ、ＰＰ−１０００を９１ｇ、１，３−ＢＤを２２ｇ、ＴＭＰを１１３ｇ仕込み、８０℃にて３時間ウレタン化反応させて、イソシアネート基含有プレポリマーＮＣＯ−Ａ１を得た。ＮＣＯ−Ａ１は、外観：淡黄色液体、イソシアネート含量：９．４％、２５℃の粘度：７０，０００ｍＰａ・ｓ、固形分：７０％であった。
【００３７】
製造例２、３
表１に示す原料を用いて、製造例１と同様にして、各イソシアネート基含有プレポリマーを得た。結果を表１に示す。
【００３８】
製造例４
攪拌機、温度計、冷却器及び窒素ガス導入管のついた容量：２Ｌの反応器に、ＴＤＩ−９０を５００ｇ、ナフテン酸マグネシウムを２ｇ仕込み、５０℃で１０時間イソシアヌレート化反応させた。その後、リン酸を０．３ｇ仕込み５０℃で１時間イソシアヌレート化停止反応させて、イソシアネート基含有プレポリマーＮＣＯ−Ｃ１を得た。ＮＣＯ−Ｃ１は、外観：淡黄色液体、イソシアネート含量：８．０％、２５℃の粘度：９００ｍＰａ・ｓ、固形分：５０％であった。
【００３９】
製造例５
表１に示す原料を用いて、製造例４と同様にして、イソシアネート基含有プレポリマーＮＣＯ−Ｃ２を得た。結果を表１に示す。
【００４０】
【表１】

【００４１】
実施例１〜３、比較例１〜２
表２に示す配合でイソシアネート基含有プレポリマーを混合し、塗料用ポリイソシアネートＮＣＯ−１〜５を調製した。
【００４２】
【表２】

【００４３】
〔塗膜物性評価〕
応用実施例１〜３、応用比較例１〜２
主剤にアルキドポリオール、硬化剤にＮＣＯ−１〜５を用いて、塗膜物性を評価した。結果を表３に示す。
【００４４】

【００４５】

【００４６】
【表３】

【００４７】
表３より、ＴＤＩのイソシアヌレート変性イソシアネート基含有プレポリマーを用いないものは、乾燥性が不十分であり、また塗膜硬度も低かった。また、液状ＭＤＩのイソシアネート基含有プレポリマーを用いないものは、塗膜の肉持ち感が不十分であり、耐溶剤性も不十分であった。一方、実施例においては、評価した物性については、全て良好な結果を示した。
【００４８】
【発明の効果】
以上説明した通り、本発明によって得られた塗料用ポリイソシアネートは、塗膜外観（特に塗膜の肉持ち感）に優れ、乾燥性、耐溶剤性、硬度に優れた塗膜が得られるものであった。なお、本発明によって得られたポリイソシアネートは二液タイプの塗料用硬化剤のみならず、一液タイプの塗料用樹脂、接着剤用の樹脂原料、二液タイプの接着剤の硬化剤、シール材、目止め材、コーティング剤に対しても有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polyisocyanate for paint. More specifically, the present invention relates to a method for producing a polyisocyanate for paints excellent in feeling of meat, solvent resistance, and hardness development.
[0002]
[Prior art]
Curing agents for paints are trimerization of urethane-modified polyisocyanate obtained by reacting organic diisocyanate and polyol, biuret-modified polyisocyanate obtained by reacting organic diisocyanate and water, organic diisocyanate or urethane-modified polyisocyanate. Isocyanurate-modified polyisocyanates obtained by reaction are widely used. For example, JP-A-3-103485 discloses a method for producing a urethane prepolymer for paint in which tolylene diisocyanate and a specific polyol are reacted. Japanese Patent Application Laid-Open No. 9-255916 discloses a moisture-curable one-component paint using a urethane prepolymer and a carbodiimide-modified diphenylmethane diisocyanate polyisocyanate in combination.
[0003]
[Problems to be solved by the invention]
However, conventional polyisocyanates for paints have not been obtained with excellent physical properties such as feeling of meat, solvent resistance and hardness development.
[0004]
In view of the above problems, an object of the present invention is to provide a method for producing a polyisocyanate for paints that is excellent in feeling of holding, solvent resistance, hardness development, and the like.
[0005]
[Means for Solving the Problems]
As a result of intensive studies, the present inventors have found that a polyisocyanate obtained by a production method using a specific raw material solves the above problems, and has completed the present invention.
[0006]
That is, in the present invention, the following (A), (B), and (C) are expressed in terms of solid content in terms of mass ratio (A) :( B) = 6/4 to 9/1, and {(A) + (B)}: (C) = 8/2 to 4/6. The method for producing a polyisocyanate for coating material, characterized by being mixed.
(A): Tolylene diisocyanate (a1) and an isocyanate content of 10 to 20 mass obtained by reacting a poly (oxypropylene) -based polyol (a2) having a nominal functional group number of 2 or more and a number average molecular weight of 200 to 2,000. % Isocyanate group-containing prepolymer.
(B): An isocyanate group-containing prepolymer having an isocyanate content of 15 to 30% by mass, obtained by reacting a carbodiimide-modified diphenylmethane diisocyanate (b1) with a low molecular polyol (b2) having a molecular weight of 250 or less and a functional group number of 2 to 3.
(C): Isocyanurate-modified prepolymer having an isocyanate content of 10 to 20% by mass, obtained by isocyanurate modification of tolylene diisocyanate (c1).
[0007]
DETAILED DESCRIPTION OF THE INVENTION
(A) in the present invention is tolylene diisocyanate (hereinafter abbreviated as TDI) (a1) and a poly (oxypropylene) -based polyol (hereinafter abbreviated as PPG-based polyol) having a number average molecular weight of 200 to 2,000. It is an isocyanate group-containing prepolymer obtained by reacting (a2).
[0008]
TDI (a1) is a single product of 2,4-tolylene diisocyanate (hereinafter abbreviated as 2,4-TDI) and 2,6-tolylene diisocyanate (hereinafter abbreviated as 2,6-TDI) or an arbitrary one. It is a mixture. Industrially, 2,4-TDI / 2,6-TDI = 100/0 to 65/35 (mass ratio) is used.
[0009]
The PPG polyol (a2) is a hydroxyl group-containing polyether having a nominal functional group number of 2 or more and a number average molecular weight of 200 to 2,000, preferably a polyether having a nominal functional group number of 2 and a number average molecular weight of 500 to 1,500. It is. When the number average molecular weight of (a2) is too large, the isocyanate content of the resulting polyisocyanate becomes small, and when this is used as a curing agent for paints, the coating film strength is hardly expressed. Moreover, when a number average molecular weight is too small, the compatibility with the polyol for main ingredients of the polyisocyanate obtained becomes small. If the nominal functional group number is too high, the resulting polyisocyanate has a higher functional group number and a higher viscosity. “Poly (oxy) propylene-based” means that the main repeating structural unit is an oxypropylene group, and that it may contain other oxyalkylene groups such as an oxyethylene group, The oxypropylene group in the repeating unit is preferably 50% by mass or more.
[0010]
(B) in the present invention is an isocyanate group obtained by reacting a carbodiimide-modified diphenylmethane diisocyanate (hereinafter abbreviated as liquid MDI) (b1) with a low molecular polyol (b2) having a molecular weight of 250 or less and having 2 to 3 functional groups. Containing prepolymer.
[0011]
Liquid MDI (b1) is obtained by decarboxylation reaction of diphenylmethane diisocyanate (hereinafter abbreviated as MDI) in the presence of a carbodiimidization catalyst. MDI (b1) is 2,2′-diphenylmethane diisocyanate (hereinafter abbreviated as 2,2′-MDI), 2,4′-diphenylmethane diisocyanate (hereinafter abbreviated as 2,4′-MDI), It is a single product or an arbitrary mixture of 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as 4,4'-MDI). Industrially, 4,4′-MDI / (2,2′-MDI + 2,4′-MDI) = 100/0 to 50/50 (mass ratio) is used.
[0012]
Examples of the low molecular polyol (b2) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5 -Pentanediol, 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,8-octanediol, 1,9-nonanediol 2,2-diethyl-1,3-propanediol, 2-n-butyl-2-ethyl-1,3-propanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl- 1,3-hexanediol, 2-n-hexadecane-1,2-ethylene glycol, 2-n-eicosane-1,2-ethylene glycol, 2 n-octacosane-1,2-ethylene glycol, diethylene glycol, dipropylene glycol, 1,4-cyclohexanedimethanol, alkylene oxide adducts such as ethylene oxide and propylene oxide of bisphenol A, hydrogenated bisphenol A, 3-hydroxy-2 , 2-dimethylpropyl-3-hydroxy-2,2-dimethylpropionate and the like, low-molecular diols such as trimethylolpropane and glycerin, and the like.
[0013]
(C) in the present invention is an isocyanate group-containing prepolymer obtained by subjecting TDI (c1) to a trimerization reaction of isocyanate groups in the presence of an isocyanuration catalyst. This (c1) may be the same as or different from the above (a1).
[0014]
If necessary, an organic diisocyanate other than (a1) may be used for (A), an organic diisocyanate other than (b1) for (B), and an organic diisocyanate other than (c1) for (C). Good. Similarly, an active hydrogen group-containing compound other than (a2) may be used for (A), and an active hydrogen group-containing compound other than (b2) may be used for (B).
[0015]
Examples of organic diisocyanates other than (a1), (b1), and (c1) include 2-nitrodiphenyl-4,4'-diisocyanate, 2,2'-diphenylpropane-4,4'-diisocyanate, 3,3 '-Dimethyldiphenylmethane-4,4'-diisocyanate,4,4'-diphenylpropane diisocyanate, m-phenylene diisocyanate, p-phenylene diisocyanate, naphthylene-1,4-diisocyanate, naphthylene-1,5-diisocyanate, 3,3 ' -Aromatic isocyanates such as dimethoxydiphenyl-4,4'-diisocyanate; aliphatic isocyanates such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, lysine diisocyanate Nate; aromatic aliphatic diisocyanates such as xylylene-1,4-diisocyanate, xylylene-1,3-diisocyanate, tetramethylxylylene diisocyanate; isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogen Examples thereof include alicyclic diisocyanates such as added tetramethylxylene diisocyanate.
[0016]
Examples of active hydrogen group-containing compounds other than (a2) and (b1) include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol and other low molecular weight monools, ethylamine, Examples include low molecular monoamines such as aniline, low molecular polyamines such as hexamethylenediamine and isophoronediamine, low molecular amino alcohols such as monoethanolamine, polymer polyols such as polyester polyol, polyether polyol, and polycarbonate polyol. .
[0017]
Next, a specific manufacturing procedure will be described.
The present invention is a production method in which (A) to (C) are produced individually and finally mixed. Hereinafter, the production methods (A) to (C) will be described.
[0018]
<Production method of (A)>
TDI (a1) and PPG polyol (a2) are reacted in an atmosphere containing excess isocyanate groups. The reaction conditions at this time are preferably a temperature of 20 to 120 ° C. and a time of 1 to 10 hours, and particularly preferably a temperature of 50 to 100 ° C. and a time of 1 to 5 hours. In this reaction, a known urethanization catalyst such as dibutyltin dilaurate or triethylenediamine can be used.
[0019]
The isocyanate content of the isocyanate group-containing urethane prepolymer thus obtained is 10 to 20% by mass, preferably 10 to 15% by mass in terms of solid content.
[0020]
<Production method of (B)>
Liquid MDI (b1) and low molecular polyol (b2) are reacted in an atmosphere containing excess isocyanate groups. The reaction conditions at this time are preferably a temperature of 20 to 120 ° C. and a time of 1 to 10 hours, and particularly preferably a temperature of 50 to 100 ° C. and a time of 1 to 5 hours. In this reaction, a known urethanization catalyst such as dibutyltin dilaurate or triethylenediamine can be used.
[0021]
The isocyanate content of the isocyanate group-containing urethane prepolymer thus obtained is 15 to 30% by mass, preferably 17 to 28% by mass in terms of solid content.
[0022]
<Production method of (C)>
TDI (c1) is heated in the presence of an isocyanurate-forming catalyst and, if necessary, a co-catalyst to cause an isocyanurate-forming reaction. The temperature in this case is preferably 30 to 70 ° C. Examples of the method for adding the isocyanurate-forming catalyst include batch charging and split charging. In the case of split charging, the catalyst charging amounts may be the same or different.
[0023]
Examples of isocyanuration catalysts include tetraalkylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and other tetraalkylammonium hydroxides, tetramethylammonium acetate, tetraethylammonium acetate, and tetrabutylammonium acetate. Weak acid salt, Trimethylhydroxypropylammonium hydroxide, Trimethylhydroxyethylammonium hydroxide, Triethylhydroxypropylammonium hydroxide, Trihydroxyhydroxyammonium hydroxide, Trihydroxyhydroxyammonium hydroxide, Trimethylhydroxypropylammonium acetate, Acetic acid Organic weak acid salts such as limethylhydroxyethylammonium salt, triethylhydroxypropylammonium acetate, triethylhydroxyethylammonium acetate, tertiary amines such as triethylamine and triethylenediamine, alkylcarboxylic acids such as acetic acid, caproic acid, octylic acid and myristic acid All known materials such as acid metal salts can be used.
[0024]
The addition amount of the isocyanurate-forming catalyst is selected from the range of 10 to 10,000 ppm with respect to (c1). Further, if the isocyanuration reaction proceeds excessively, gelation is likely to occur, and thus the desired shape cannot be obtained. Therefore, when the isocyanate content becomes 10 to 20% by mass in terms of solid content, a catalyst poison to be described later is charged to stop the isocyanuration reaction.
[0025]
The catalyst poison used for stopping the isocyanuration reaction includes acidic phosphoric acid esters such as phosphoric acid, phosphorous acid, ethyl phosphate and diethyl phosphate, and acidic phosphorous acid such as ethyl phosphite and diethyl phosphite. Examples include esters, sulfur, hydrochloric acid, nitric acid, sulfuric acid, toluenesulfonic acid, toluenesulfonic acid esters, organic peroxides such as benzoyl peroxide, and organic acid halides such as acetic acid chloride. The amount of catalyst poison used is preferably 0.8 to 2 equivalents relative to the isocyanurate-forming catalyst.
[0026]
<Common to (A) to (C)>
In addition, when obtaining (A)-(C), it is more preferable from the viewpoint of reaction control and a viscosity fall to use the organic solvent at the time of reaction. The timing of charging the organic solvent is preferably at least before the isocyanuration reaction. Examples of the organic solvent include aliphatic hydrocarbon organic solvents such as n-hexane and octane, alicyclic hydrocarbon organic solvents such as cyclohexane and methylcyclohexane, ketone organics such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Solvents, ester organic solvents such as methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate Glycol ether ester organic solvents such as diethyl ether, tetrahydrofuran, dioxane and other organic solvents such as methyl chloride, methylene chloride, chloroform, carbon tetrachloride, methyl bromide, methylene iodide, Halogenated aliphatic hydrocarbon organic solvents chloroethane, etc., N- methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, polar aprotic solvents such as hexamethylphosphoric phosphonyl amides. The said solvent can be used 1 type, or 2 or more types.
[0027]
After the isocyanuration reaction, unreacted organic diisocyanate such as TDI can be removed if necessary. Examples of methods for removing unreacted TDI and the like include known methods such as distillation, reprecipitation, and extraction.
[0028]
<Mixing of (A) to (C)>
The mixing of (A) to (C) is not particularly limited, and a known stirring device can be used. The ratios of (A) to (C) are (A) :( B) = 6/4 to 9/1, and {(A) + (B)}: C) = 8/2 to 4/6, preferably (A) :( B) = 7/3 to 9/1 and {(A) + (B)} :( C) = 7/3 ~ 5/5. When (A) is too much, the coating film strength tends to be insufficient. When (B) is too much, the storage stability tends to be insufficient. When there is too much (C), a coating film tends to become weak. When (A) is too small, the flexibility of the coating film tends to be insufficient. When there is too little (B), a feeling of flesh tends to become insufficient. When the amount of (C) is too small, the drying property tends to be insufficient.
[0029]
The viscosity of 25 ° C. paint polyisocyanates obtained by the present invention is not more than 2,000 mm ² / s, preferably 100~1,800mm ² / s.
[0030]
The polyisocyanate obtained by the present invention includes, as necessary, an antioxidant, an ultraviolet absorber, a pigment, a dye, a solvent, a flame retardant, a hydrolysis inhibitor, a lubricant, a plasticizer, a filler, and storage stability. An additive such as an agent can be appropriately blended.
[0031]
The polyisocyanate obtained by the present invention is most suitable as a curing agent for a two-component polyurethane paint. The main agent is a polyol used in the field of two-component polyurethane coatings, for example, aliphatic hydrocarbon polyols, fluorine polyols, polyether polyols, polyester polyols, polycarbonate polyols, epoxy resins, acrylic polyols, And one kind of alkyd polyols or a mixture thereof. In particular, fluorine polyols and acrylic polyols are more preferable because of their excellent weather resistance. These polyols have two or more hydroxyl groups in one molecule and are produced by known techniques such as solution polymerization and condensation reaction.
[0032]
The main component polyol preferably has a hydroxyl value of 1 to 300 mgKOH / g, preferably 10 to 150 mgKOH / g, more preferably 20 to 100 mgKOH. A hydroxyl value of less than 1 mgKOH / g is not preferable because the coating film becomes brittle. When the hydroxyl value exceeds 300 mgKOH / g, the surface smoothness of the coating film may be impaired, or the coating film may become hard and brittle, which is not preferable.
[0033]
The equivalent ratio of isocyanate group to hydroxyl group of the main component polyol and polyisocyanate is isocyanate group / hydroxyl group = 9/1 to 1/9, preferably 8/2 to 2/8. When the hydroxyl group is excessive from the above range, the coating film may become brittle. When the isocyanate group is excessive, the coating film may become brittle because a large amount of polyisocyanate that does not participate in crosslinking exists.
[0034]
【Example】
The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited thereto. Unless otherwise indicated in Examples and Comparative Examples, “%” means “mass%” and the ratio means mass ratio.
[0035]
[Production of isocyanate group-containing prepolymer]
The raw materials used in each production example are as follows.

[0036]
Production Example 1
Capacity with stirrer, thermometer, cooler and nitrogen gas inlet tube: 1L reactor, 300g butyl acetate, 474g TDI-100, 91g PP-1000, 22g 1,3-BD, TMP Preparation of 113 g and urethane reaction at 80 ° C. for 3 hours gave an isocyanate group-containing prepolymer NCO-A1. NCO-A1 had an appearance: a pale yellow liquid, an isocyanate content: 9.4%, a viscosity at 25 ° C .: 70,000 mPa · s, and a solid content: 70%.
[0037]
Production Examples 2 and 3
Each isocyanate group-containing prepolymer was obtained in the same manner as in Production Example 1 using the raw materials shown in Table 1. The results are shown in Table 1.
[0038]
Production Example 4
500 g of TDI-90 and 2 g of magnesium naphthenate were charged into a 2 L reactor equipped with a stirrer, a thermometer, a cooler, and a nitrogen gas inlet tube, and wasocyanurated at 50 ° C. for 10 hours. Thereafter, 0.3 g of phosphoric acid was charged and subjected to isocyanuration termination reaction at 50 ° C. for 1 hour to obtain an isocyanate group-containing prepolymer NCO-C1. NCO-C1 had an appearance: a pale yellow liquid, an isocyanate content: 8.0%, a viscosity at 25 ° C .: 900 mPa · s, and a solid content: 50%.
[0039]
Production Example 5
An isocyanate group-containing prepolymer NCO-C2 was obtained in the same manner as in Production Example 4 using the raw materials shown in Table 1. The results are shown in Table 1.
[0040]
[Table 1]

[0041]
Examples 1-3, Comparative Examples 1-2
The isocyanate group-containing prepolymer was mixed with the formulation shown in Table 2 to prepare polyisocyanates NCO-1 to 5 for coating.
[0042]
[Table 2]

[0043]
[Evaluation of coating film properties]
Application Examples 1-3, Application Comparative Examples 1-2
The physical properties of the coating film were evaluated using alkyd polyol as the main agent and NCO-1 to 5 as the curing agent. The results are shown in Table 3.
[0044]

[0045]

[0046]
[Table 3]

[0047]
From Table 3, those using no TDI isocyanurate-modified isocyanate group-containing prepolymer had insufficient drying properties and low coating film hardness. In addition, when the liquid MDI isocyanate group-containing prepolymer was not used, the feeling of the film was insufficient and the solvent resistance was insufficient. On the other hand, in the examples, all the evaluated physical properties showed good results.
[0048]
【The invention's effect】
As explained above, the polyisocyanate for coatings obtained by the present invention is excellent in coating film appearance (particularly the feeling of film durability), and can provide a coating film excellent in drying properties, solvent resistance, and hardness. there were. The polyisocyanate obtained by the present invention is not only a two-component type curing agent for paints, but also a one-component type coating resin, a resin raw material for adhesives, a curing agent for two-component adhesives, and a sealing material. It is also useful for sealing materials and coating agents.

Claims (1)

The following (A), (B), and (C) are expressed in terms of solid content (A): (B) = 6/4 to 9/1, and {(A) + (B)} : (C) = 8/2 to 4/6. The method for producing a polyisocyanate for paints, characterized in that mixing is performed.
(A): Tolylene diisocyanate (a1) and an isocyanate content of 10 to 20 mass obtained by reacting a poly (oxypropylene) -based polyol (a2) having a nominal functional group number of 2 or more and a number average molecular weight of 200 to 2,000. % Isocyanate group-containing prepolymer.
(B): An isocyanate group-containing prepolymer having an isocyanate content of 15 to 30% by mass, obtained by reacting a carbodiimide-modified diphenylmethane diisocyanate (b1) with a low molecular polyol (b2) having a molecular weight of 250 or less and a functional group number of 2 to 3.
(C): Isocyanurate-modified prepolymer having an isocyanate content of 10 to 20% by mass, obtained by isocyanurate modification of tolylene diisocyanate (c1).