JPH0368023B2 - - Google Patents

Description

[Detailed description of the invention]

A. Industrial Application Field The present invention relates to a method for producing a compound having an isocyanurate ring and an isocyanate group, which is useful as a curing agent in producing polyurethane paints, for example. More specifically, a method for producing a compound having an isocyanurate ring and an isocyanate group from an isocyanate compound, which is characterized by using a hydroxyalkyl quaternary ammonium compound as a catalyst and an organic phosphite ester as a co-catalyst. Regarding. B. Prior Art A compound having an isocyanurate ring and an isocyanate group, which is also generally called an isocyanate trimer, usually has three or more reactive isocyanate groups at each end, and also has weather resistance, heat resistance, and chemical resistance in the molecule. It has an isocyanurate ring with excellent properties, and has a low vapor pressure and is easy to handle, so it is used as a curing agent in the production of polyurethane paints, for example. Such isocyanate trimers are usually manufactured by using organic polyisocyanate as a raw material and applying a catalyst to the organic polyisocyanate. Conventionally, as a catalyst that has the effect of isocyanurating,
For example, many compounds have been proposed to date, including tertiary amines, metal salts of organic acids, and tertiary phosphines. Recently, hydroxyalkyl quaternary ammonium compounds, especially hydroxyalkyl quaternary ammonium hydroxides (for example, JP-A-55-38380, JP-A-Sho 54- 119480) or hydroxyalkyl quaternary ammonium carboxylates (for example, JP-A-52-17484, JP-A-Sho
55-143978) is reported to be effective. C Problems to be Solved by the Invention The quaternary ammonium compound catalyst described above exhibits catalytic action even when used in a relatively small amount, but its action is easily affected by impurities present in extremely small amounts in the raw materials. In particular, when using industrially produced and sold organic polyisocyanates as raw materials, the effect may be difficult to develop, and once the effect occurs, the isocyanurate reaction proceeds rapidly and the reaction liquid Problems such as gelation remain. Further, in general, in the isocyanurate reaction using a catalyst, it is inevitable that the product becomes colored and cloudy. These coloring and turbidity depend on the type of catalyst and reaction temperature, but are also greatly affected by the amount of catalyst used. Although the above-mentioned quaternary ammonium compounds are somewhat improved in terms of coloring and turbidity of the product compared to conventionally known isocyanurate catalysts, these problems still remain to be solved. do not have. The present inventors have conducted intensive studies on isocyanurate catalysts that are easy to control the isocyanurate reaction and do not cause coloration or turbidity in the reaction product, and have found that using a hydroxyalkyl quaternary ammonium compound as a catalyst, It has been found that when this catalyst is further used in combination with an organic phosphite, strong catalytic activity is exhibited even when the amount of catalyst used is extremely small. In other words, it has been found that although organic phosphite itself does not have a catalytic effect on isocyanurate formation, it acts as a so-called co-catalyst, which significantly enhances the catalytic effect of quaternary ammonium. The present invention has been made based on this knowledge. D Means for Solving the Problems The present invention is characterized in that an isocyanurate ring and an isocyanate group are reacted by reacting an isocyanate compound in the presence of an organic phosphite using a hydroxyalkyl quaternary ammonium compound as a catalyst. This is a method for producing a compound having Examples of the hydroxyalkyl quaternary ammonium compounds used as catalysts in the present invention include hydroxyalkyl quaternary ammonium carboxylate (hereinafter sometimes abbreviated as carboxylate catalyst) and hydroxyalkyl quaternary ammonium hydroxide (hereinafter sometimes abbreviated as carboxylate catalyst). , sometimes abbreviated as hydroxide catalyst).
All of these compounds are known as catalysts for converting organic polyisocyanates into isocyanurates, and these known catalysts can be used as they are. Carboxylate catalysts are obtained by reacting a tertiary amine with an alkylene oxide in the presence of an organic carboxylic acid in a solvent such as dipropylene glycol. Examples of such substances include trimethyl-N-2-hydroxypropylammonium 2-ethylhexanoate, N,N-dimethyl-N-hydroxyethyl-
N-2-hydroxypropylammonium hexanoate, trimethyl-N-2-hydroxypropylammonium hexadecanoate, trimethyl-N-2-hydroxypropylammonium phenyl carbonate, trimethyl-N-2
Examples include, but are not limited to, -hydroxypropylammonium formate. Hydroxy catalysts can also be obtained by reacting tertiary amines and alkylene oxides in water/methanol. These include, for example, 2-hydroxyethyl-trimethylammonium hydroxide, 2-hydroxyethyl-trimethylammonium hydroxide,
-Hydroxyethyl-dodecyl-dimethylammonium hydroxide, 2-hydroxyethyl-dimethyl-2,2'-dihydroxymethyl-butylammonium hydroxide, monoadduct of ethylene oxide and 1,4-diazabicyclo-2,2,2-octane These examples include, but are not limited to these in any way. Examples of the organic phosphite used as a cocatalyst in the present invention include organic phosphite diester and organic phosphite triester.
These compounds are in the molecule

[formula] or teeth

It has one or more (usually 1 to 4) partial structures of the formula: (wherein one hand of the oxygen atom is bonded to a carbon atom). In the present invention, it is preferable to use organic phosphorous acid triesters, and specific examples of such ones include the following. (i) (R-O) _-3P [However, R is the same or different and is alkyl having 1 to 20 carbon atoms or 1 carbon number
-20 aryl optionally substituted with alkyl (aryl is, for example, phenyl). These include, for example, triethyl phosphite, tributyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris(tridecyl) phosphite, tristearyl phosphite; triphenyl phosphite, tris (nonylphenyl)phosphite, tris(2,
4-di-t-butylphenyl) phosphite;
or monophosphites such as diphenyldecyl phosphite and diphenyl (tridecyl) phosphite; (iii) di-tri or tetraphosphites derived from polyhydric alcohols such as tetra-tridecyl pentaerythrityl tetraphosphite, tetraphenyl dipropylene glycol diphosphite, tripentaerythritol triphosphite;・Alkyl (C _1-20 ) ・Bisphenol A. Diphosphite, 4,4'-butylidene-
bis(3-methyl-6-t-butylphenyl-
(iv) other polyphosphites, such as hydrogenated bisphenol A phosphite polymers (molecular weight 2400-3000). Furthermore, as the organic phosphite diester, (RO) _-2P (o)H [however,
R has the same meaning as defined above], and examples of such diesters include dilauryl hydrogen phosphite and diphenyl hydrogen phosphite. Alkyl of the symbol R may be substituted with halogen, such as chloro, for example tris(2,3-dichloropropyl)phosphite. Further, the oxygen atom of the above-mentioned phosphite may be substituted with a sulfur atom, such as trilauryl trithiophosphite. In the process of the present invention, such a cocatalyst is used in combination with a catalyst, and the catalyst itself may be used in an amount less than the most effective amount when used alone. For example, in the case of a carboxylate catalyst, 0.002 to 0.05% by weight (preferably
0.005-0.018% by weight), and in the case of hydroxide catalysts 0.001-0.05% by weight (preferably 0.002-0.018% by weight)
0.009% by weight) shows sufficient catalytic activity. The amount of phosphite used as a cocatalyst is approximately 1/10 to 10 times the amount of the catalyst, preferably equivalent to 6 times the amount of the catalyst. If the amount is less than this amount, the action as a promoter will not be sufficient, and if it exceeds this amount, the product obtained by the reaction will be utilized. It may adversely affect the physical properties of the final product. Further, as the isocyanate compound that can be used as a raw material in the present invention, there can be mentioned a compound having an isocyanate group that has been conventionally used in the production of an isocyanate trimer. Examples of such compounds include organic polyisocyanates. Examples of the organic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3
-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate,
Aliphatic diisocyanates such as 2,6-diisocyanate methyl caproate, e.g. 1,3-
Cyclopentane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3.5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane Diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, 1,
Cycloalkylene diisocyanates such as 3-bis(isocyanatomethyl)cyclohexane,
For example, m-phenylene diisocyanate, p-
Phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate , dianisidine isocyanate, aromatic diisocyanates such as 4,4'-diphenyl ether diisocyanate, e.g. ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,
Aroaliphatic diisocyanates such as ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3-tetramethylxylylene diisocyanate, 1,4-tetramethylxylylene diisocyanate, etc. , for example triphenylmethane-4,
4',4''-triisocyanate, 1,3,5-triisocyanatebenzene, 1,3,5-triisocyanatecyclohexane, 2,4,6-triisocyanatetoluene, ω-isocyanateethyl-2,6-diisocyanate triisocyanates such as proate. Among these organic polyisocyanates, aliphatic diisocyanates and cycloalkylene diisocyanates are isocyanate compounds that can be advantageously used in the present invention. mixtures (e.g. hexamethylene diisocyanate and 3-isocyanatomethyl-
It may also be used in a mixture with 3,5,5-trimethylcyclohexyl isocyanate). moreover,
These organic polyisocyanates are reacted with mono- to tetrahydric alcohols or polyols such as polyester polyols and polyether polyols at a ratio such that the NCO/OH value is approximately 20-30. Urethane prepolymers having groups can be used as raw materials in the present invention. As a monohydric alcohol,
For example, methanol, butanol, 2-ethylhexanol, ethylene glycol monomethyl ether, etc.; examples of dihydric alcohols include ethylene glycol, 1,3-butanediol,
1,4-butanediol, propylene glycol, neopentyl glycol, 1,6-hexanediol, 2-ethylhexanediol, 2,2,
4-trimethylpentadiol and the like; trihydric alcohols such as trimethylolpropane and glycerin; tetrahydric alcohols such as pentaerythritol; polyester polyols such as neopentyl hivalate glycol ester; Examples of the ether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, and the like. In the method of the present invention, such an isocyanate compound is used as a raw material, a catalyst and a cocatalyst are added thereto, and the compound is subjected to an isocyanurate reaction. The isocyanurate reaction of the present invention is usually carried out at 30 to 100°C.
Preferably it is carried out at 40-80°C. The progress of the reaction is
It can be tracked by measuring the NCO group content and viscosity. The reaction is carried out to a predetermined amount (in the present invention, the NCO group content is approximately 90 to 50% of that at the start of the reaction).
After allowing the reaction to proceed (until the reaction decreases to ), a terminating agent is added to stop the reaction. An acidic substance is used as the reaction terminator. As acidic substances,
Examples include inorganic acids such as hydrochloric acid and phosphoric acid, and organic acid chlorides such as benzoyl chloride and acetyl chloride. These terminators may be added in an amount of about 1/2 to twice the weight of the catalyst used. Although the method of the present invention proceeds without a solvent, if necessary, acetate esters such as ethyl acetate, butyl acetate, and cellosolve acetate, or phosphate esters such as trimethyl phosphate and triethyl phosphate may be used as a solvent. It's okay. After the reaction is completed, unreacted isocyanate monomer usually remains in the reaction solution, but this can be distilled off under reduced pressure. The same applies to solvents. A vacuum thin film distillation apparatus is preferably used to distill off unreacted isocyanate monomers. By this method, the unreacted isocyanate monomer content can be reduced to approximately 3% by weight or less, and if necessary approximately 1% by weight.
It can be: In this way, a compound having an isocyanurate ring and an isocyanate group is obtained. When an organic diisocyanate is used as a raw material, the main component of this product is a trimer having one isocyanurate ring and three isocyanate groups produced by the reaction of three organic diisocyanates, and other It contains a pentamer (2 isocyanurate rings and 4 isocyanate groups) and a heptamer (3 isocyanurate rings and 5 isocyanate groups). The method of the invention reduces the trimer content to approximately 40
~70% (analysis by liquid chromatography; area ratio) can be produced. In the method of the present invention, the isocyanurate reaction progresses stably at a constant rate regardless of the purity of the raw materials, so the reaction is easy to control, and the isocyanurate reaction progresses rapidly at a certain point. The reaction solution will not gel. Furthermore, since the compound having an isocyanurate ring and an isocyanate group produced by the method of the present invention is transparent and has almost no color,
It can be used as a hardening agent without any filtration or decolorization, and has extremely high commercial value. That is, the object of the present invention can be widely used as a raw material for producing paints, adhesives, foams, etc. with excellent physical properties such as weather resistance and heat resistance by reacting with various polyol components for urethane. , extremely useful. Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 Hexamethylene diisocyanate (hereinafter referred to as
HDI (abbreviated as HDI) was placed in a four-diameter glass flask, heated to 50°C, and then trimethyl-
N-2-hydroxypropylammonium 2-
0.05 g of ethylhexanoate, then 0.25 g of tetraphenyl dipropylene glycol diphosphite
Add g. When this mixture was allowed to react at 60°C for 3 hours with stirring, the NCO group content was approximately 80% at the start of the reaction.
%. At this point, 0.05 g of benzoyl chloride was added to stop the reaction. The obtained reaction solution was heated to a thin film distillation device (vacuum degree 0.7 mgHg; temperature
(150°C) to remove unreacted HDI monomer, and a pale yellow transparent product was obtained. This thing is
NCO group content 21.0%, viscosity (25℃) 2300cps.Hue
It was APHA30. Since absorption at 1680 cm ^-1 was observed in the infrared absorption spectrum of this product, it was confirmed that it had an isocyanurate ring. Examples 2 to 9 Compounds having an isocyanurate ring and an isocyanate group were obtained in the same manner as in Example 1 using the formulations and conditions shown in Tables-a and -b. In addition,
The isocyanuration reaction is carried out in the case of hexamethylene diisocyanate (HDI), with an NCO group content of approximately 40%, and 3-isocyanatomethyl-
In the case of 3,5,5-trimethylcyclohexyl isocyanate (IPDI), the NCO group content is approximately 30
%, the reaction was stopped. The physical properties of the isocyanurate reaction solution and the product obtained by distilling off unreacted monomers are shown in Table (a).
and b) shown in the bottom column.

【table】

[Table] Unreacted monomers were removed by distillation.
Example 10 Hexamethylene diisocyanate (HDI) 500
g and 10 g of ethylene glycol in a glass container
The mixture was placed in a diameter flask and subjected to urethanization reaction at 75°C for 2 hours under a nitrogen stream to obtain a reaction solution containing a urethane prepolymer having an NCO group at the end. This reaction solution was cooled to 50°C, and trimethyl-N-2-
Add 0.05 g of hydroxypropylammonium 2-ethylhexanoate and 0.25 g of tetraphenyldipropylene glycol diphosphite at 60°C.
The isocyanurate reaction was carried out. When the NCO group content of this reaction solution reached approximately 40% (about 3 hours), 0.05 g of benzoyl chloride was added to stop the reaction. The unreacted HDI monomer in the reaction solution was distilled off using a thin film distillation apparatus to obtain a pale yellow transparent liquid. This product had an NCO group content of 20.0%, a viscosity (25°C) of 2500 cps, and a hue of APHA30. In addition, absorption at 1680 cm ^-1 was observed in the red line absorption spectrum, which confirmed that it had an isocyanurate ring. Examples 11 to 16 Compounds having an isocyanurate ring and an isocyanate group were obtained in the same manner as in Example 10 using the formulation and conditions shown in the table. The isocyanurate reaction is performed when the NCO group content is approximately 40% in the case of hexamethylene diisocyanate raw material (HDI), and in the case of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (IPDI) raw material. The reaction was stopped when the NCO group content reached approximately 30%. The physical properties of the isocyanurate reaction solution and the product obtained by distilling off unreacted monomers are shown in the lower column of the table.

【table】

Claims (1)

[Claims] 1. A method for producing a compound having an isocyanurate ring and an isocyanate group, which comprises reacting an isocyanate compound in the presence of an organic phosphite using a hydroxyalkyl quaternary ammonium compound as a catalyst.