JP2002020452A - Biuret type polyisocyanate composition and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a biuret type polyisocyanate composition which is colorless and no muddiness of a product, particularly no muddiness of the product at a lower temperature, and to establish a manufacturing method of the biuret type polyisocyanate composition including an efficient purification method. SOLUTION: The biuret type polyisocyanate composition is obtained from at least one or more selected from aliphatic and alicyclic diisocyanate monomers wherein concentration of a urea dimer is not more than 0.5 wt.% and transmissivity is not more than 90%, and a manufacturing method of the biuret type polyisocyanate composition comprises the steps of: (a) reacting at least one or more selected from the aliphatic and alicyclic diisocyanate monomers with a biuret reaction agent in a mole ratio of 4-40, (b) adjusting concentration of the unreacted diisocyanate monomers in the reaction solution to 3-20 wt.%, and (c) heating the adjusted solution obtained from step (b) at 110 deg.C-160 deg.C in the condition of maintaining not less than 90% of transmissivity of the reaction solution to set concentration of the urea dimer as not more than 0.5 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biuret-type polyisocyanate composition substantially free of urea dimer and diisocyanate monomer obtained from aliphatic or alicyclic diisocyanate monomers and a method for producing the same.

[0002]

2. Description of the Related Art Polyisocyanate compositions containing substantially no diisocyanate monomer are used for coatings, adhesives,
Widely used for sealing materials, waterproofing materials, foams, elastomers, fiber treatment agents, etc. Biuret-type polyisocyanate composition having a biuret group in the molecule,
It can be obtained using a diisocyanate monomer as a main raw material and water, a monohydric tertiary alcohol, formic acid, hydrogen sulfide, an organic primary amine, an organic secondary amine or the like as a biuretizing agent. There are many proposals regarding these manufacturing methods. For example, JP-A-49-134629 and JP-A-63-1
No. 74961, JP-B-61-60093, JP-B-61-26778, and JP-B-62-41496.
JP, JP-B2-62545, JP-B-5-17
No. 222, Japanese Unexamined Patent Publication No. 8-225511 and the like have been proposed.

A precursor of a biuret bond is a urea bond, and an isocyanate group reacts with the urea bond to form a biuret bond. When the urea bond-containing compound is mixed in the polyisocyanate composition, turbidity may occur, and for example, a coating film using the compound may have poor physical properties. Therefore, for example, the continuous production method
JP-B-41496, JP-B-63-6544, JP-B-5-17222, which is a batch production method, and JP-B-2
In JP-A-62545 and JP-A-8-225511, the reaction liquid is maintained at a high temperature after the addition of the biuretating agent to the diisocyanate monomer. As described above, when the polyisocyanate composition is maintained at a high temperature, coloring may occur, and the economic burden such as productivity and capital investment of the polyisocyanate composition has been increased.

In Japanese Patent Publication No. Sho 62-41496, a urea dimer or a polymer containing a urea bond is efficiently reacted with a diisocyanate, and the urea dimer or a polymer containing a urea bond is not mixed into the polyisocyanate composition. For this purpose, the reaction solution is treated in a pipe reactor. However, in this method, the reaction is carried out at a high diisocyanate concentration of about 77 to 89% by weight, and the efficiency of reducing the urea dimer concentration is still low, so that the polyisocyanate generates turbidity at a low temperature. In addition, the above mentioned Japanese Patent Publication No. 61-600
No. 93, in order to suppress the increase of diisocyanate monomer during long-term storage, by heating the biuret-type polyisocyanate composition, by increasing the diisocyanate monomer in advance, to eliminate the substance causing the diisocyanate monomer Is described. However, there is no description of a urea dimer, no description or suggestion of low-temperature turbidity of a polyisocyanate composition mixed with a urea dimer. Naturally, urea dimer reduction and coloring of the polyisocyanate composition are simultaneously performed. There is no description or suggestion of the conditions to be satisfied.

On the other hand, polyisocyanate compositions are usually produced in the presence of a large excess of diisocyanate monomer.
In order to obtain a polyisocyanate composition as a product, a purification step for removing unreacted diisocyanate monomers having a high vapor pressure is required. As a method there is a low-polarity solvent, extraction using a gas in a critical state, and the like,
In many cases, a scraping thin film still is used. The scraping-type thin-film evaporator has a small heat history, so the product is less thermally denatured, and is suitable for removing low-boiling substances from high-viscosity substances.

When a polyisocyanate composition is obtained by evaporating and separating low-boiling components such as diisocyanate monomer from a mixed solution containing a polyisocyanate composition and a diisocyanate monomer by a scraping-type thin-film evaporator, the distillate of the mixed solution is removed. When the amount of feed to is increased, a phenomenon (hereinafter referred to as “entre”) in which a high-boiling polyisocyanate composition is mixed in the separated low-boiling components may occur. This phenomenon not only reduces the product yield, but also increases the viscosity of the polyisocyanate composition when the recovered diisocyanate monomer is used as a raw material again, by mixing the polyisocyanate composition into the raw material. It is easy to change the reaction conditions in some cases.

[0007]

SUMMARY OF THE INVENTION The present invention relates to the establishment of a biuret-type polyisocyanate composition which is free of color and does not cause turbidity of the product, especially at low temperatures, and a production method including an efficient purification method. is there.

[0008]

As mentioned above, in the process of biuret formation, various side reactions occur, and various urea bond-containing compounds called polyureas are formed. The present inventors have conducted intensive studies and found that the cause of product turbidity, especially product turbidity at low temperatures, is those by-products.
The inventors have determined that the urea is a urea dimer, specified the urea dimer concentration at which turbidity occurs, and found out that the dissolved gas in the reaction solution was the cause of the entre. The urea dimer referred to in the present invention is a compound having one urea bond obtained from two molecules of a diisocyanate monomer.

That is, the present invention is as follows. And a biuret-type polyisocyanate composition having a urea dimer concentration of 0.5% by weight or less and a transmittance of 90% or less, obtained from at least one selected from aliphatic and alicyclic diisocyanate monomers. (A) reacting at least one or more selected from aliphatic and alicyclic diisocyanate monomers with a biuretizing agent at a molar ratio of 4 to 40; (b) adjusting the concentration of unreacted diisocyanate monomer in the reaction solution to 3 to 40; Adjusting the concentration to 20% by weight, and adding the adjusted liquid obtained in the steps (c) and (b) to 1%.
A biuret-type poly (C) comprising heating the mixture at a temperature of 10 ° C to 160 ° C and maintaining the transmittance of the reaction solution at 90% or more to reduce the urea dimer concentration to 0.5% by weight or less. A method for producing an isocyanate composition. A method for producing a biuret-type polyisocyanate composition, wherein the diisocyanate monomer is hexamethylene diisocyanate. A method for producing a biuret-type polyisocyanate composition, wherein the biuretizing agent is water.

A method for producing a biuret-type polyisocyanate composition, wherein the reaction is carried out in the presence of a solvent (1) and / or (2) shown below. (1)

Embedded image (Wherein, R ^1, R ² may be different and are both the same alkyl group or an acyl group having 1 to 4 carbon atoms, R ³
Is a methyl group or hydrogen, and n is an integer of 1-2. (2) Alkyl phosphoric acid

A process for producing a biuret-type polyisocyanate composition according to any one of the above, wherein the diisocyanate monomer is removed by thin-film distillation. A method for producing a biuret-type polyisocyanate composition, wherein, in the step of removing diisocyanate monomers by thin-film distillation, the reaction solution is degassed and then fed to the still. After the step (a) of reacting the diisocyanate monomer with the biuretizing agent is performed under stirring and homogenization, the reaction solution is further introduced into a pipe reactor, and the reaction is further advanced under an extrusion flow in the pipe reactor. A method for producing any of the above biuret-type polyisocyanate compositions.

Hereinafter, the present invention will be described in detail. The diisocyanate monomer used in the present invention is an aliphatic or alicyclic diisocyanate monomer. As the aliphatic and alicyclic diisocyanate monomers, for example, those having 4 to 30 carbon atoms are preferable as aliphatic diisocyanates, and those having 8 to 30 carbon atoms are preferable as alicyclic diisocyanates. Tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6
-Hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate,
Examples thereof include 1,3-bis (isocyanatomethyl) -cyclohexane and 4,4′-dicyclohexylmethane diisocyanate. Especially on an industrial scale,
1,6-hexamethylene diisocyanate (hereinafter “HD
I "), isophorone diisocyanate (hereinafter referred to as" I ").
PDI ") can be carried out on a large scale, and can be used alone or in combination of two or more. The preferred diisocyanate monomer is HDI.

The biuret-type polyisocyanate composition can be obtained by reacting the diisocyanate monomer with a biuretizing agent. As biuretizing agents,
Water, monovalent tertiary alcohol, formic acid, hydrogen sulfide, organic primary monoamine, organic primary diamine and the like can be mentioned, and water is preferred. In the reaction, 4 mol or more, preferably 5 mol or more of the diisocyanate monomer can be used per 1 mol of the biuretizing agent, and is 40 mol or less, preferably 30 mol or less, more preferably 20 mol or less. If the mole is less than 4, the viscosity of the obtained polyisocyanate composition will be high, the compatibility with the base polyol may be reduced, and the solid content of the coating material may be reduced. On the other hand, if it exceeds 40 moles, the yield of the polyisocyanate composition will decrease, and the economics of productivity will decrease.

A solvent can be used during the reaction. The solvent dissolves the biuretating agent such as diisocyanate monomer and water and forms a homogeneous phase under the reaction conditions. That is,
The amount required to form a homogeneous phase is added. Thereby, generation of by-products such as polyurea can be suppressed. A solvent having a low solubility of the biuretizing agent such as water is undesirably increased in the amount added and becomes uneconomical when the solvent is separated and recovered after the completion of the reaction. This solvent preferably has a solubility of a biuretizing agent such as water of 0.5% by weight or more. Further, the boiling point of the solvent is preferably lower than the boiling point of the raw material diisocyanate monomer in consideration of recovery and separation of unreacted diisocyanate and the like. Solvents shown below do not react with isocyanate groups and are preferred because they are hydrophilic.

[0015]

Embedded image (Wherein, R ^1, R ² may be different and are both the same alkyl group or an acyl group having 1 to 4 carbon atoms, R ³
Is a methyl group or hydrogen, and n is an integer of 1-2. )

Specific examples of the solvent include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol. Glycol mono-
n-butyl ether acetate, ethylene glycol diacetate, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol di-n-propyl ether, ethylene glycol diisopropyl ether, ethylene glycol di-n-butyl ether, ethylene glycol methyl ethyl ether, ethylene Glycol methyl isopropyl ether,

Ethylene glycol methyl-n-butyl ether, ethylene glycol ethyl-n-propyl ether, ethylene glycol ethyl isopropyl ether, ethylene glycol ethyl-n-butyl ether,
Ethylene glycol-n-propyl-n-butyl ether, ethylene glycol isopropyl-n-butyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol mono-n-propyl ether acetate, diethylene glycol monoisopropyl ether acetate, diethylene glycol mono-n-
Butyl ether acetate, diethylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol di-n-propyl ether,

Diethylene glycol diisopropyl ether, diethylene glycol di-n-butyl ether,
Diethylene glycol methyl ethyl ether, diethylene glycol methyl isopropyl ether, diethylene glycol methyl-n-propyl ether, diethylene glycol methyl-n-butyl ether, diethylene glycol ethyl isopropyl ether, diethylene glycol ethyl-n-propyl ether, diethylene glycol ethyl-n-butyl ether, diethylene glycol-n-propyl -N-butyl ether, diethylene glycol isopropyl-n-butyl ether, and the like,

For example, propylene glycol based propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol mono-n-propyl ether acetate, propylene glycol monoisopropyl ether acetate, propylene glycol mono-n-butyl ether acetate, propylene Glycol diacetate, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol diisopropyl ether, propylene glycol di-n-butyl ether, propylene glycol methyl ethyl ether, propylene glycol methyl isopropyl ether,

Propylene glycol methyl-n-butyl ether, propylene glycol ethyl-n-propyl ether, propylene glycol ethyl isopropyl ether, propylene glycol ethyl-n-butyl ether, propylene glycol-n-propyl-n-butyl ether, propylene glycol isopropyl-n −
Butyl ether, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, dipropylene glycol mono-n
-Propyl ether acetate, dipropylene glycol monoisopropyl ether acetate, dipropylene glycol mono-n-butyl ether acetate, dipropylene glycol diacetate, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether,

Dipropylene glycol di-n-propyl ether, dipropylene glycol diisopropyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol methyl ethyl ether, dipropylene glycol methyl isopropyl ether, dipropylene glycol methyl n-propyl ether,
Dipropylene glycol methyl-n-butyl ether,
Dipropylene glycol ethyl isopropyl ether,
Dipropylene glycol ethyl-n-propyl ether, dipropylene glycol ethyl-n-butyl ether, dipropylene glycol-n-propyl-n-butyl ether, dipropylene glycol isopropyl-n
-Butyl ether, and the like,

Preferred ethylene glycol solvents include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol diacetate, diethylene glycol dimethyl ether and the like. Preferred propylene glycol solvents include propylene glycol monomethyl ether acetate. Propylene glycol monoethyl ether acetate, propylene glycol diacetate, dipropylene glycol dimethyl ether and the like.

Alkyl phosphate solvents are preferred because they do not react with isocyanate groups and have hydrophilicity. Examples of the alkyl phosphate solvent include, for example, trimethyl phosphate,
Examples thereof include triethyl phosphate, tripropyl phosphate, and tributyl phosphate, with trimethyl phosphate and triethyl phosphate being preferred. These can be used alone or in combination of two or more. A preferred solvent mixture weight ratio is 3/7 to 9/1 ethylene glycol-based solvent / phosphoric acid-based solvent, and a preferred use amount is 20 to 50% by weight based on the total weight of the raw material diisocyanate monomer and the solvent. In some cases, an OH acidic compound such as di (2-ethylhexyl) phosphate exemplified in JP-A-8-225511 can be added.

The reaction temperature is preferably from 70 ° C. to 200 ° C., and more preferably from 90 ° C. to 180 ° C. These reactions can be carried out in a batch system, but a continuous method is preferred from the viewpoint of productivity and the like. In particular, after the reaction of the diisocyanate monomer and the biuretizing agent disclosed in JP-B-62-41496 is carried out under stirring and homogenization, the reaction product is further led to a pipe reactor, and the product is extruded through the pipe reactor. Continuous production in which the reaction proceeds below is preferred.

The diisocyanate monomer and, if necessary, the solvent are removed from the reaction solution obtained in this way, to obtain a specific diisocyanate monomer concentration. The concentration thereof is 3 to 20% by weight, preferably 3 to 15% by weight, more preferably 3 to 20% by weight based on the total of the diisocyanate monomer and the polyisocyanate composition.
10% by weight. If the concentration exceeds 20% by weight or less than 3% by weight, the rate of reduction of urea dimer decreases, which is not preferable. Thus, it was surprising that the specific low diisocyanate monomer concentration further increased the reduction rate of urea dimer. This is because the urea bond of the urea dimer reacts with the isocyanate group, is converted to a biuret bond, and disappears. In that case, it is generally believed that a higher isocyanate group concentration leads to a faster reduction of the urea dimer.

That is, it was considered that a high diisocyanate monomer concentration is preferable for a rapid reduction of the urea dimer, but the reduction rate of the urea dimer is lower when the diisocyanate monomer concentration is 20% by weight or less and the isocyanate group concentration is low. Being fast was surprising. The present invention is based on this finding. The temperature of step (c) of the present invention is 110 to 1
The temperature is 60C, preferably 110-140C. If the treatment temperature is lower than 110 ° C., the reduction rate of the urea dimer decreases, which is not preferable. If the temperature exceeds 160 ° C., a colored polyisocyanate composition may be obtained, which is not preferable.

In the step (c) of the present invention, the transmittance of the concentrated solution is 9
Keep 0% or more. The measurement of the transmittance in the present invention is a transmittance at a cell length of 2 cm and a wavelength of 430 nm. When the value is less than 90%, the obtained polyisocyanate composition is colored. The processing time for that is 5 to 90 minutes, preferably 5 to 60 minutes, and more preferably 5 to 30 minutes. The concentration of the urea dimer in the concentrated solution after the treatment (the concentration relative to the composition excluding the diisocyanate monomer and the solvent, that is, the concentration relative to the total amount of the biuret-type polyisocyanate composition, the urea dimer and the multimer containing urea bonds) Urea dimer content) is 0.5% by weight or less, preferably 0.3% by weight or less. If the concentration exceeds 0.5% by weight, turbidity may occur when the polyisocyanate composition is stored at a low temperature of 5 ° C. or lower. The above processing can be performed in either a batch system or a continuous system. The liquid residence time in that case can be performed at almost the same residence time because the reduction rate of the urea dimer is zero-order reactive. In the present invention, it is necessary to perform the treatment in the above step (c) under a specific diisoanate monomer concentration, and thereafter, the diisocyanate monomer is removed as necessary.

In order to achieve a specific diisocyanate monomer concentration, extraction with a poor solvent, a critical fluid or the like can be performed, but a scraping type thin film still is preferable. The scraping type thin film evaporator forcibly forms a thin film,
The low-boiling diisocyanate monomer is efficiently evaporated and separated from the polyisocyanate composition. When feeding the reaction solution to the scraping-type thin film still, it is preferable to degas the reaction solution in advance. Water as biuretizing agent,
When producing a biuret-type polyisocyanate composition, carbon dioxide gas is generated as a by-product gas, and it has become clear that a part of this carbon dioxide gas is dissolved in the reaction solution.
Although the amount of dissolved gas varies depending on the production conditions, it is 0.05 to 0.1.
4Nml gas / ml liquid.

When a reaction solution containing a dissolved gas is fed to the thin film distillation apparatus which is a vacuum system, the dissolved gas is vaporized,
Foam. At the time of vaporization and foaming, a part of the reaction solution scatters and adheres to a cooler for condensing the dissocyanate monomer vapor as a mist. As a result, the reaction liquid is mixed into the separated and recovered diisocyanate monomer. This phenomenon becomes remarkable as the amount of liquid fed to the still increases. In addition to the uneconomical effect that the yield of the polyisocyanate composition is reduced, the polyisocyanate composition is mixed with the recovered diisocyanate monomer, so that the product obtained from the raw material increases the viscosity of the polyisocyanate. Causes fluctuation. This phenomenon is remarkable in the reaction for producing a polyisocyanate composition, for example, when a by-product gas such as carbon dioxide gas is generated as in a biuret-type polyisocyanate composition using a biuret agent such as water. is there. Although the concentration varies depending on the conditions, it may reach several percent.

The invention according to the present invention is based on the clarification of this phenomenon,
It is based on the finding that the degassing of the dissolved gas before feeding the reaction solution to the thin-film still can prevent the polyisocyanate composition from being mixed into the recovered diisocyanate monomer. For degassing the reaction solution, a tank having a degree of vacuum operated in substantially the same manner as that of the distillation apparatus is provided, and the reaction solution is dropped from the upper part of the tank. The reaction solution begins to degas upon dropping. If the reaction solution that has reached the liquid level in the tank is not completely degassed, the liquid level becomes foamy and is degassed. When the reaction solution is fed to the liquid phase portion of the tank, degassing may not be completely performed, which is not preferable. Although a stirrer can be provided in the tank, the tank is a vacuum system, the structure becomes complicated, and the economic burden increases. The temperature of the reaction solution when fed to the still is preferably equal to or lower than the boiling point of the reaction solution. If the temperature is higher than the boiling point, entre is likely to occur, which is not preferable.

The scraping type thin film evaporator used for removing the diisocyanate monomer and the like may be provided in series, and the diisocyanate monomer may be removed in two stages.
In that case, degassing can be performed at each stage. The polyisocyanate composition thus obtained is substantially free of diisocyanate monomers. Usually, the diisocyanate monomer concentration is at most 5% by weight, preferably at most 2% by weight, more preferably at most 1% by weight. The isocyanate group concentration of the polyisocyanate composition is 3 to
25% by weight, viscosity at 25 ° C. 500 to 50,000
mPa · s and the number average molecular weight is about 550 to 1,000. The urea dimer concentration is 0.5% by weight or less, preferably 0.3% by weight or less. If it exceeds 0.5% by weight,
May produce turbidity at low temperatures. The transmittance of the obtained polyisocyanate composition is 90% or more.

Next, an example of the present invention will be described with reference to the drawings.
In FIG. 1, a raw material diisocyanate monomer is continuously supplied at a constant flow rate from a raw material introduction pipe 2 to a first reactor 4 composed of a complete mixing tank type stirring tank. On the other hand, the biuret agent is also supplied from the introduction pipe 1 to the first reactor 4 at the same constant flow rate. The first reactor 4 includes a stirrer 3 and a heating jacket 3A. Gas generated by the reaction is discharged through an exhaust pipe 13 and a condenser 14.
5 is a pipe connecting the first reactor 4 to the second reactor 7. Like the first reactor, the second reactor 7 also includes a complete mixing type stirrer 6 and a heating jacket 6A. Exhaust pipe 1
5 and the condenser 16. Second reactor 7
Are connected via a pipe 8 to pipe reactors 9, 10 and 11 configured in multiple stages. The conditions of the pipe reactor are as follows.

Temperature: 80 to 180 ° C., preferably 90 to 180 ° C.
160 ° C., pressure: normal pressure, reaction time (residence time): 30 to
240 minutes, preferably 30 to 120 minutes, flow rate: 0.5 to
5 m / Hr, preferably 0.5 to 2 m / Hr. Each pipe reactor is provided with jackets 9A, 10A, and 11A.
Emitted via 8. The reaction liquid is continuously withdrawn through the pipe 12 to the intermediate tank 19 and fed to the deaerator 20. The reaction solution degassed by the degassing device is fed to a scraping-type thin-film evaporator 21, and the adjustment solution is supplied to the adjustment tank 2.
The liquid is transferred to 3, and the diisocyanate monomer and the like are taken out from 22. The diisocyanate monomer and the like are further removed by a scraping type thin film still 24, and the polyisocyanate composition is taken out from 26.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples. (1) Measurement of concentration of urea dimer The urea dimer is represented by the general formula OCNR-NHC (= O) NH-R
Expressed as NCO. R is each independently an aliphatic group or an alicyclic group derived from diisocyanate. For example, in the case of hexamethylene diisocyanate, the area% of a peak having a peak top near a molecular weight of 310 by gel permeation chromatography (hereinafter, “GPC”) analysis described below was defined as the weight% of the urea dimer.・ Carrier: Tetrahydrofuran (hereinafter “TH
F ") (flow rate: 0.6 ml / min) Column:" TSKgel SuperH1000 ",
"TSKgel SuperH2000", "TSKg
el SuperH3000 "(all manufactured by Tosoh Corporation)
Columns were connected in series. -Detector: Refractometer-GPC device: "HLC-8120GPC" (manufactured by Tosoh Corporation)

(2) Measurement of Isocyanate Group Concentration The isocyanate group concentration of the polyisocyanate was defined as the content (% by weight) of the isocyanate group contained in the polyisocyanate, and was measured by the following method. 5 to 10 g of polyisoacinate was precisely weighed and dissolved in 20 ml of toluene. To the resulting solution, 20 ml of a 2N toluene solution of n-dibutylamine was added, and left at room temperature for 15 minutes to carry out a reaction. After the completion of the reaction, APB-41 manufactured by Kyoto Electronics Co., Ltd.
Using a type 0 automatic titrator, the total amount of the obtained reaction mixture was back-titrated with 1 N hydrochloric acid, and the volume of 1 N hydrochloric acid required for neutralization of unreacted n-dibutylamine in the reaction mixture (sample titration amount) ). On the other hand, the same operation as described above was performed except that the polyisocyanate was not used, and similarly, the volume of 1 N hydrochloric acid required for neutralization of unreacted n-dibutylamine (blank titer) was determined. Isocyanate group concentration (% by weight) = [{Blank titer (ml) -sample titer (ml)} × 42 / {sample weight (g) × 1000}] × 100

(3) Measurement of Diisocyanate Monomer Concentration The root area of the peak having a retention time corresponding to the molecular weight of the diisocyanate monomer was determined by GPC under the same conditions as in (1) above. Determine the percentage of this peak area to the total area of all peaks in the chromatogram,
The value was taken as the diisocyanate monomer concentration (% by weight). (4) Measurement of Number Average Molecular Weight A solution of polyisocyanate dissolved in THF (concentration:
About 0.25% by weight) under GPC under the same conditions as in (1) above.
And measured as a number average molecular weight in terms of polystyrene.

(5) Measurement of viscosity The viscosity was measured at 25 ° C. using a VISCONIC ED type or E type viscometer manufactured by Tokimec. (6) Transmittance The transmittance at a cell length of 2 cm and a wavelength of 430 nm was measured with an ultraviolet-visible spectrophotometer (UV-160, manufactured by Shimadzu Corporation). (7) Storage Stability at 5 ° C. After leaving the polyisocyanate composition in a colorless and transparent glass container sealed with nitrogen at 5 ° C. for 1 day, the presence or absence of turbidity was visually observed.

[0038]

Example 1 A flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing pipe was placed in a nitrogen atmosphere, and then the HD was removed.
I: 700 parts by weight, trimethylphosphoric acid: 150 parts by weight, methyl cellosolve acetate: 150 parts by weight, water: 15 parts by weight (HDI / water molar ratio = 5)
It was kept at 0 ° C. for 1 hour. The obtained reaction solution (unreacted diisocyanate monomer concentration: 65% by weight) was vacuumed at 655.
500g in a scraping type thin film evaporator with Pa and temperature of 160 ℃
/ Hr. The obtained biuret-type polyisocyanate composition having a diisocyanate monomer concentration of 5% by weight, a urea dimer concentration of 1.5% by weight, and a transmittance of 94% was kept under a nitrogen atmosphere at a liquid temperature of 140 ° C. for 30 minutes.
The monomer concentration was 0.2% by weight or less, and the transmittance was 93%.
This polyisocyanate composition is fed again to a scraping-type thin film still (vacuum degree 67 Pa, temperature 160 ° C.),
Diisocyanate monomer concentration 0.3 wt%, urea dimer concentration 0.2 wt% or less, transmittance 93%, isocyanate group concentration 22.9 wt%, viscosity 3700 mPa · s / 2
A biuret-type polyisocyanate composition having a number average molecular weight of 690 at 5 ° C was obtained. No turbidity occurred after the evaluation of storage stability at 5 ° C.

[0039]

Example 2 A reaction solution (concentration of unreacted diisocyanate monomer) obtained in the same manner as in Example 1 except that the amount of water charged was changed to 9.4 parts by weight (HDI / water molar ratio = 8). : 70% by weight) and fed to a scraping still in the same manner as in Example 1 to obtain a biuret-type polyisocyanate composition having an unreacted diisocyanate monomer concentration of 4% by weight and a urea dimer concentration of 1%. 0.1% by weight and transmittance 95%. Under nitrogen atmosphere of this composition 110
After holding at 60 ° C. for 60 minutes, the concentration of the urea dimer was 0.2% by weight or less, and the transmittance was 95%. This composition was fed again to a scraping-type thin film evaporator, and a diisocyanate monomer concentration of 0.3% by weight, a urea dimer concentration of 0.2% by weight or less,
94% transmittance, 23.8% by weight isocyanate group concentration,
Viscosity 1600 mPa · s / 25 ° C., number average molecular weight 635
Of a biuret-type polyisocyanate composition was obtained. 5 ℃
No turbidity occurred in the evaluation of storage stability.

[0040]

Example 3 HDI was added to the concentrate obtained after the first scraping-type thin film distillation obtained in Example 2 to obtain an HDI concentration of 10%.
Adjusted to% by weight. 125 ° C. under nitrogen atmosphere of this composition
, The concentration of the urea dimer after holding for 30 minutes was 0.2% by weight or less, and the transmittance was 95%. The polyisocyanate composition is fed again to a scraping-type thin film evaporator, and a diisocyanate monomer concentration of 0.3% by weight, a urea dimer concentration of 0.2% by weight or less, a transmittance of 94%, and an isocyanate group concentration of 23.7% by weight. %, Viscosity 1600 mPa · s / 25 ° C.,
A biuret-type polyisocyanate composition having a number average molecular weight of 635 was obtained. No turbidity occurred in the 5 ° C storage stability evaluation.

[0041]

Comparative Example 1 HDI was added to the concentrate obtained in Example 2 after the first scraping-type thin-film distillation, and the HDI concentration was 5%.
It was adjusted to 0% by weight. 125 ° C under a nitrogen atmosphere of this composition
, The concentration of the urea dimer after holding for 30 minutes was 0.5% by weight and the transmittance was 95%. This polyisocyanate composition was fed again to a scraping-type thin-film evaporator, and a diisocyanate monomer concentration of 0.3% by weight and a urea dimer concentration of 1.0% were used.
Weight%, transmittance 92%, isocyanate group concentration 23.8
A biuret-type polyisocyanate composition having a weight% of 1600 mPa · s / 25 ° C. and a number average molecular weight of 635 was obtained. Turbidity occurred in the storage stability evaluation at 5 ° C.

[0042]

Comparative Example 2 The concentration of the urea dimer of the concentrate obtained after the first scraping thin film distillation obtained in Example 2 was kept at 100 ° C. for 15 minutes in a nitrogen atmosphere at 0.8% by weight. Liquid permeability 95
%Met. The polyisocyanate composition was fed again to a scraping-type thin film evaporator, and the unreacted diisocyanate monomer concentration was 0.3% by weight, the urea dimer concentration was 0.8% by weight, the transmittance was 95%, and the isocyanate group concentration was 23.8. A biuret-type polyisocyanate composition having a weight% of 1600 mPa · s / 25 ° C. and a number average molecular weight of 635 was obtained. Turbidity occurred after storage at 5 ° C.

[0043]

Comparative Example 3 The concentration of the urea dimer of the concentrated solution obtained in Example 2 after the first scraping-type thin film evaporation was maintained at 150 ° C. for 120 minutes in a nitrogen atmosphere and was 0.2% by weight or less. And the liquid transmittance was 88%. This polyisocyanate composition was fed again to a scraping-type thin-film evaporator, and the unreacted diisocyanate monomer concentration was 0.3% by weight, the urea dimer concentration was 0.2% by weight or less, the transmittance was 87%, and the isocyanate group concentration was 23. 8% by weight, viscosity 1600 mPa · s / 25 ° C.
A biuret-type polyisocyanate composition having a number average molecular weight of 635 was obtained. Although no turbidity occurred in the evaluation of storage stability at 5 ° C., the obtained polyisocyanate composition was colored.

[0044]

Comparative Example 4 A flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing pipe was placed in a nitrogen atmosphere, and then was subjected to HD.
I: 700 parts by weight, trimethylphosphoric acid: 150 parts by weight, methyl cellosolve acetate: 150 parts by weight, water: 15 parts by weight (HDI / water molar ratio = 5)
It was kept at 0 ° C. for 1 hour. The obtained reaction solution (unreacted diisocyanate monomer concentration: 65% by weight) was vacuumed at 655.
500g in a scraping type thin film evaporator with Pa and temperature of 160 ℃
/ Hr. The obtained liquid is further vacuumed to 67P.
a, A biuret type polyisocyanate composition having a diisocyanate monomer concentration of 0.5% by weight, a urea dimer concentration of 1.5% by weight, and a transmittance of 94% was obtained by feeding the mixture to a scraping still at a temperature of 160 ° C. As a result of heating the polyisocyanate composition at 110 ° C. for 30 minutes, the isocyanate monomer concentration was 0.5% by weight, the urea dimer concentration was 1.2% by weight, the isocyanate group concentration was 22.9% by weight, and the transmittance was 9%.
4%, viscosity 3700 mPa · s / 25 ° C., and number average molecular weight 690. Turbidity occurred in the storage stability evaluation at 5 ° C.

[0045]

EXAMPLE 4 Using the continuous reactor shown in FIG. 1, 1000 parts by weight of hexamethylene diisocyanate and 500 parts by weight of an equal weight mixture of methyl cellosolve acetate and trimethyl phosphate were added to the first reactor 4 per hour. The feed was continuous. On the other hand, water was continuously supplied to the first reactor at a rate of 7.1 parts by weight per hour (HDI
/ Water molar ratio = 15). The temperatures of the first reactor 4, the second reactor 7, and the third reactor (pipe reactor) 9, 10, and 11 are 120 ° C, 150 ° C, 160 ° C, residence time 90 minutes,
The adjustment was made for 60 minutes and 60 minutes. The reaction solution thus obtained (unreacted diisocyanate monomer concentration:
(83% by weight, dissolved gas amount: 0.25 nml / ml) is fed to the upper gas phase of the deaerator 20 set at a vacuum of 655 Pa and a temperature of 30 ° C., and the reaction liquid is scraped off from the lower liquid phase to distill it by distillation. Vessel 21 (vacuum degree 655 Pa, temperature 160 ° C)
Feed. The concentration of the polyisocyanate composition in the recovered diisocyanate monomer and the solvent is 0.5%.
Weight or less.

The obtained concentrate had a diisocyanate monomer concentration of 5% by weight, a urea dimer concentration of 1.0% by weight, and a transmittance of 93%. After heating the concentrated solution at 130 ° C. for 30 minutes, the urea dimer concentration was 0.2% by weight or less and the transmittance was 91%. This liquid is scraped again and the thin-film evaporator (degree of vacuum 67P)
a, temperature 160 ° C.) to obtain a biuret-type polyisocyanate composition. The physical properties of the obtained polyisocyanate composition were a viscosity of 900 mPa · s / 25 ° C., an isocyanate group concentration of 24.7% by weight, a urea dimer concentration of 0.2% by weight or less, a transmittance of 91%, and an isocyanate group concentration of 24. 7% by weight, diisocyanate monomer concentration was 0.5% by weight, viscosity was 900 mPa · s / 25 ° C., and number average molecular weight was 600. No turbidity occurred in the 5 ° C storage stability evaluation.

[0047]

Example 5 Example 4 except that the amount of water fed was 10.7 parts by weight per hour (unreacted diisocyanate monomer concentration: 73% by weight, HDI / water molar ratio = 10).
The same was done. The urea dimer concentration after heating the concentrated solution from the first scraping type thin film distillation apparatus was 0.2% by weight or less, the transmittance was 94%, and the polyisocyanate composition finally obtained was urea 2 Monomer concentration 0.2% by weight or less, transmittance 9
The viscosity was 1700 mPa · s / 25 ° C., the number average molecular weight was 615, the isocyanate group concentration was 24.4% by weight, and the diisocyanate monomer concentration was 0.4% by weight. The concentration of the polyisocyanate composition in the recovered diisocyanate monomer and the solvent was 0.5% by weight or less. No turbidity occurred in the 5 ° C storage stability evaluation.

[0048]

[Reference Example 1] The same operation as in Example 5 was performed except that no deaerator was used. The obtained polyisocyanate composition had a viscosity of 1700 mPa · s / 25 ° C., a number average molecular weight of 615, an isocyanate group concentration of 24.4% by weight, and a diisocyanate monomer concentration of 0.5% by weight. Then, the concentration of the polyisocyanate composition in the diisocyanate monomer and the solvent recovered in the first scraping-type thin film still was 4% by weight.

[0049]

Reference Example 2 Diisocyanate monomer recovered by the first scraping-type thin-film still without using a deaerator,
The procedure was performed in the same manner as in Reference Example 1 except that a solvent was used. The resulting polyisocyanate composition has a viscosity of 2010 mPa · s
/ 25 ° C, number average molecular weight 665, isocyanate group concentration 2
3.6% by weight, diisocyanate monomer concentration is 0.5
% By weight. Then, the concentration of the polyisocyanate composition in the diisocyanate monomer and the solvent recovered in the first scraping-type thin film still was 4% by weight.

[0050]

The biuret-type polyisocyanate composition of the present invention has no coloring and has a low urea dimer concentration. Also,
The urea dimer can be efficiently reduced, the polyisocyanate composition is not mixed into the recovered diisocyanate monomer, and the productivity is improved. In addition, even if the recovered diisocyanate monomer is reused, the viscosity of the polyisocyanate composition can be reduced. There is no increase, the yield is high, and an economically excellent production method can be provided. The biuret-type polyisocyanate composition thus obtained has properties such as excellent stability especially at low temperatures, and is in the fields of urethanes and isocyanates such as paints, adhesives, fiber treatment agents, sealing materials, waterproofing materials, foams, and elastomers. Useful in

[Brief description of the drawings]

FIG. 1 shows a flowchart of a continuous reactor used in one embodiment of the present invention.

[Explanation of symbols]

 4 First Reactor 7 Second Reactor 9, 10, 11 Pipe Reactor 19 Intermediate Tank 20 Deaerator 21, 24 Scraping Type Thin Film Distiller 23 Adjustment Tank

Continuation of the front page (72) Inventor Atsushi Yasukawa 1-Takeshima-cho, Hyuga City, Miyazaki Prefecture Asahi Kasei Corporation F-term (reference) 4J034 HB08 KA01 KB01 KB03 QA05 QA07 QB15 QC01 RA07 RA08 RA09

Claims (8)

[Claims] 1. A urea dimer concentration obtained from at least one kind selected from aliphatic and alicyclic diisocyanate monomers having a urea dimer concentration of 0.5% by weight or less and a transmittance of 90% or less.
% Biuret type polyisocyanate composition. 2. (a) reacting at least one or more selected from aliphatic and alicyclic diisocyanate monomers with a biuretizing agent at a molar ratio of 4 to 40; (b) unreacted diisocyanate monomer in the reaction solution 3 ~ 2 concentration
0% by weight, the adjusted liquid obtained in the steps (c) and (b) is adjusted to 110 ° C. to 160 ° C., and the transmittance of the reaction liquid is 90%.
Heating was performed under the above-mentioned conditions to maintain the urea dimer concentration at 0.5.
2. The method for producing a biuret-type polyisocyanate composition according to claim 1, further comprising the step of reducing the content by weight to at most 1. 3. The method for producing a biuret-type polyisocyanate composition according to claim 2, wherein the diisocyanate monomer is hexamethylene diisocyanate. 4. The method for producing a biuret-type polyisocyanate composition according to claim 2, wherein the biuretizing agent is water. 5. The method for producing a biuret-type polyisocyanate composition according to claim 4, wherein the reaction is carried out in the presence of a solvent (1) and / or (2) shown below. (1) (Wherein, R ^1, R ² may be different and are both the same alkyl group or an acyl group having 1 to 4 carbon atoms, R ³
Is a methyl group or hydrogen, and n is an integer of 1-2. (2) Alkyl phosphoric acid 6. The method for producing a biuret-type polyisocyanate composition according to claim 2, wherein the diisocyanate monomer is removed by thin-film distillation. 7. The method for producing a biuret-type polyisocyanate composition according to claim 6, wherein in the step of removing the diisocyanate monomer by thin-film distillation, the reaction solution is degassed and then fed to the still. 8. After the step (a) of reacting a diisocyanate monomer with a biuretizing agent is performed under stirring and homogenization, the reaction solution is further introduced into a pipe reactor, and the reaction solution is extruded under the flow of extrusion into the pipe reactor. The method for producing a biuret-type polyisocyanate composition according to any one of claims 2 to 7, wherein the reaction is a continuous reaction for further promoting the reaction.