JP2017132924A - Method for producing biuret type polyisocyanate composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a biuret type polyisocyanate product which prevents coloring at the time of production of a polyisocyanate body, and has a small amount of a diisocyanate monomer immediately after production and during long-term storage.SOLUTION: There is provided a method for producing a biuret type polyisocyanate composition which includes: (a) a step of reacting a diisocyanate monomer and a biuretization agent in the presence of a phosphoric acid ester-based compound; (b) a step of adjusting the concentration of an unreacted diisocyanate monomer in a reaction liquid to 3-20 wt.%; (c) a step of heating an adjustment liquid obtained in the step (b) on conditions of 110-160°C, a cell length of the reaction liquid of 5 cm, and a transmittance at a wavelength of 430 nm of 85% or more; and (d) a step of reducing the concentration of a residual diisocyanate monomer to less than 0.3%, where in the step (a), a weight ratio of the phosphoric acid ester-based compound and an aliphatic diisocyanate compound is in a range of 3:100 to 18:100.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a biuret type polyisocyanate composition.

  Until now, several methods using water as a biuret agent in the presence of a phosphoric ester compound have been proposed for the purpose of obtaining a product having no coloration or turbidity when producing a biuret type polyisocyanate. Patent Documents 1 to 5 disclose manufacturing methods relating to these and techniques relating to biuret-type polyisocyanate compositions obtained thereby.

Japanese Examined Patent Publication No. 62-41496 Japanese Patent Publication No. 7-14466 Japanese Patent No. 4152026 Japanese Patent No. 4367988 Japanese Patent No. 4514293

However, the production methods disclosed in Patent Documents 1 to 5 still have problems in terms of achieving both the degree of coloring of the produced polyisocyanate composition and the amount of residual monomers.
The present invention lies in the establishment of a method for producing a biuret-type polyisocyanate composition that is free from coloring and that can keep the amount of diisocyanate present in the product low immediately after production and after long-term storage of the product.

  As a result of intensive studies to solve the above problems, the present inventor is able to meet the purpose by synthesizing and producing a certain amount of a phosphoric ester compound at the time of producing biuret type polyisocyanate. The present invention has been made based on this finding.

（式中、Ｒ¹ 、Ｒ² は炭素数１〜４のアルキル基またはアシル基で両者は同一であっても異なっても良く、Ｒ³ はメチル基または水素、ｎは１〜２の整数である。）
［６］
前記工程（ｄ）において、ジイソシアネートモノマーを薄膜蒸留で除く工程を含む、［１］〜［５］のいずれかに記載のビウレット型ポリイソシアネート組成物の製造方法。
［７］
前記ジイソシアネートモノマーを薄膜蒸留で除く工程において、前記反応液を脱気後、前記蒸留器にフィードする、［６］に記載のビウレット型ポリイソシアネート組成物の製造方法。
［８］
前記工程（ａ）が、攪拌均質下行われた後、更に前記反応液をパイプリアクターに導き、該パイプリアクター中押出し流れ下で反応を更に進行せしめる連続反応である、［１］〜［７］のいずれかに記載のビウレット型ポリイソシアネート組成物の製造方法。 That is, the present invention is as follows.
[1]
(A) a step of reacting at least one diisocyanate monomer selected from the group consisting of an aliphatic diisocyanate monomer and an alicyclic diisocyanate monomer with a biuret agent in the presence of a phosphate ester compound, (b) The step of adjusting the unreacted diisocyanate monomer concentration to 3 to 20% by weight, (c) the adjustment solution obtained in step (b) is 110 ° C. to 160 ° C., the cell length of the reaction solution is 5 cm, and the transmittance is 430 nm. A step of heating under a condition of maintaining 85% or more, and (d) a step of reducing the residual diisocyanate monomer concentration to less than 0.3%. In the step (a), a phosphate ester compound and an aliphatic diisocyanate compound For producing a biuret-type polyisocyanate composition, wherein the weight ratio is from 3: 100 to 18: 100
[2]
The method for producing a biuret type polyisocyanate composition according to [1], wherein the phosphate ester compound is trimethyl phosphate.
[3]
The method for producing a biuret type polyisocyanate composition according to [1] or [2], wherein the diisocyanate monomer is hexamethylene diisocyanate.
[4]
The method for producing a biuret type polyisocyanate composition according to any one of [1] to [3], wherein the biuretizing agent is water.
[5]
The biuret type polyisocyanate according to any one of [1] to [4], wherein in the step (a), the diisocyanate monomer is reacted with the biuret agent in the presence of a solvent represented by the following general formula (1). A method for producing the composition.

(Wherein R ¹ and R ² are alkyl groups or acyl groups having 1 to 4 carbon atoms, which may be the same or different, R ³ is a methyl group or hydrogen, and n is an integer of 1 to 2) is there.)
[6]
The method for producing a biuret-type polyisocyanate composition according to any one of [1] to [5], including a step of removing the diisocyanate monomer by thin film distillation in the step (d).
[7]
The method for producing a biuret type polyisocyanate composition according to [6], wherein in the step of removing the diisocyanate monomer by thin film distillation, the reaction solution is degassed and then fed to the distiller.
[8]
[1] to [7], wherein the step (a) is a continuous reaction in which the reaction liquid is further introduced into a pipe reactor after the stirring and homogenization, and the reaction is further advanced under an extrusion flow in the pipe reactor. The manufacturing method of the biuret type polyisocyanate composition in any one.

  According to the production method of the present invention, the degree of coloring during production is small, and it is possible to reduce both the amount of diisocyanate monomer in the biuret-type polyisocyanate composition at any stage from production to long-term storage. Become.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The following embodiments are examples for explaining the present invention, and are not intended to limit the present invention to the following contents. The present invention can be implemented with appropriate modifications within the scope of the gist thereof.

  In the production method of the present embodiment, (a) a step of reacting at least one diisocyanate monomer selected from the group consisting of an aliphatic diisocyanate monomer and an alicyclic diisocyanate monomer with a biuret agent in the presence of a phosphate ester compound. (B) a step of adjusting the unreacted diisocyanate monomer concentration in the reaction solution to 3 to 20% by weight, (c) the adjustment solution obtained in step (b) is 110 ° C. to 160 ° C., and the cell length of the reaction solution A step of heating under the condition that the transmittance of 5 cm and a wavelength of 430 nm is maintained at 85% or more, (d) a step of reducing the residual diisocyanate monomer concentration to less than 0.3%, and in the step (a), phosphoric acid Biuret type polyisocyanate in which the weight ratio of the ester compound and the aliphatic diisocyanate compound is in the range of 3: 100 to 18: 100. A method for producing a sulfonate compositions.

The diisocyanate monomer used in the present embodiment is at least one selected from the group consisting of aliphatic and alicyclic diisocyanate monomers.
As the aliphatic and alicyclic diisocyanate monomers, for example, aliphatic diisocyanates having 4 to 30 carbon atoms are preferable, and alicyclic diisocyanates having 8 to 30 carbon atoms are preferable. Tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, 1,3-bis (isocyanate methyl) ) -Cyclohexane, 4,4′-dicyclohexylmethane diisocyanate and the like. In particular, on an industrial scale, 1,6-hexamethylene diisocyanate (hereinafter referred to as “HDI”) and isophorone diisocyanate (hereinafter referred to as “IPDI”) can be carried out on a large scale and used alone or in combination of two or more. You can also A preferred diisocyanate monomer is HDI.

  In the step (a), the diisocyanate monomer and the biuretizing agent are reacted to obtain a biuret type polyisocyanate composition. Examples of the biuretizing agent include water, monovalent tertiary alcohol, formic acid, hydrogen sulfide, organic primary monoamine, and organic primary diamine, preferably water.

  In the above reaction, 4 mol or more, preferably 5 mol or more of the diisocyanate monomer can be used with respect to 1 mol of the biuretizing agent, and it 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 resulting polyisocyanate composition is increased, the compatibility with the main component polyol may be reduced, and the solid content of the paint may be reduced. On the other hand, when it exceeds 40 mol, the yield of the polyisocyanate composition is lowered, and the economic efficiency of production is lowered.

In this embodiment, from the viewpoint of preventing coloration and reducing the amount of diisocyanate present in the product immediately after production and after long-term storage of the product, the step (a) is performed in the presence of a phosphate ester compound. Done in Phosphate ester compounds refer to phosphate triester compounds and acidic phosphate esters. Examples of phosphate triester compounds include trimethyl phosphate, triethyl phosphate, tripropyl phosphate, and tributyl phosphate. Examples of acidic phosphate esters include ethyl phosphate, diethyl phosphate, isopropyl phosphate, diisopropyl phosphate, butyl phosphate, dibutyl phosphate, 2-ethylhexyl phosphate, di (2-ethylhexyl) phosphate, and the like. It is done. In the present embodiment, the phosphate ester compound may be used alone or in combination of two or more, or a phosphate triester compound and an acidic phosphate ester may be used in combination. As the phosphate ester compound, a phosphate triester compound is preferably used, and among them, trimethyl phosphate and triethyl phosphate are preferable.
Moreover, the usage-amount of a phosphate ester type compound is 3-18 weight part with respect to 100 weight part of raw material diisocyanate monomers, Preferably it is 5-15 weight part, More preferably, it is 5-10 weight part.

  A solvent can be used in the reaction. The solvent dissolves the diisocyanate monomer and the biuretizing agent such as water and forms a homogeneous phase under the reaction conditions. That is, an amount necessary to form a homogeneous phase is added. Thereby, production of by-products such as polyurea can be suppressed. A solvent having a low solubility of the biuretizing agent such as water is not preferable because the amount of addition increases accordingly, and the solvent is separated and recovered after completion of the reaction. This solvent preferably has a solubility of a biuretizing agent such as water of 0.5% by weight or more. In addition, the boiling point of the solvent is preferably lower than the boiling point of the raw diisocyanate monomer in consideration of recovery and separation of unreacted diisocyanate and the like. A solvent represented by the following general formula (1) is preferable because it does not react with an isocyanate group and is hydrophilic.

（式中、Ｒ¹、Ｒ²は炭素数１〜４のアルキル基またはアシル基で両者は同一であっても異なっても良く、Ｒ³はメチル基または水素、ｎは１〜２の整数である。）

(Wherein R ¹ and R ² are alkyl groups or acyl groups having 1 to 4 carbon atoms, which may be the same or different, R ³ is a methyl group or hydrogen, and n is an integer of 1 to 2) is there.)

Specific examples of this solvent include, for example, ethylene glycol-based ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol mono-n-propyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene 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- Chill 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- -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 isopropyl ether Propyl ether, diethylene glycol ethyl-n-butyl ether, diethylene glycol-n-propyl-n-butyl ether, diethylene glycol isopropyl-n-butyl ether, etc., for example, propylene glycol monopropyl ether glycol, 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 iso Propyl 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, Propylene 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 Ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene N-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.
These solvents can be used alone or in admixture of two or more.

  The mixing weight ratio of the solvent represented by the general formula (1) and the phosphate ester compound is such that the solvent / phosphate ester compound represented by the general formula (1) is 3/7 to 9/1. Preferably, the amount of the solvent represented by the above general formula (1) and the phosphoric acid ester compound is preferably such that the solvent represented by the above general formula (1) and phosphoric acid with respect to the total weight of the raw material diisocyanate monomer and the solvent The total amount of the ester compound is in the range of 15 to 50% by weight.

  The reaction temperature is preferably 70 ° C. or higher and 200 ° C. or lower, more preferably 90 ° C. or higher and 180 ° C. or lower. These reactions can be carried out batchwise, but a continuous method is preferable from the viewpoint of productivity. In particular, after the reaction of the diisocyanate monomer and biuret agent disclosed in Japanese Examined Patent Publication No. Sho 62-41496 is carried out under homogeneous stirring, the reaction product is further introduced into a pipe reactor, and the extrusion flow in the pipe reactor is carried out. Continuous production, in which the reaction proceeds under, is preferred.

  The diisocyanate monomer, and optionally the solvent, are removed from the reaction solution thus obtained to obtain a specific diisocyanate monomer concentration. The concentration of the diisocyanate monomer is 3 to 20% by weight, preferably 3 to 15% by weight, more preferably 3 to 10% by weight based on the total of the diisocyanate monomer and the polyisocyanate composition. If this concentration exceeds 20% by weight or less than 3% by weight, the decrease rate of the urea dimer decreases, which is not preferable.

  The temperature of the process (c) of this embodiment is 110-160 degreeC, Preferably it is 110-140 degreeC. When the treatment temperature is less than 110 ° C., the rate of decrease of the urea dimer is lowered, which is not preferable. If it exceeds 160 ° C., a colored polyisocyanate composition may be obtained, which is not preferable.

  In the step (c) of the present embodiment, a state where the concentrated liquid permeability is 85% or more is maintained. The transmittance in the present embodiment is a transmittance at a cell length of 5 cm and a wavelength of 430 nm. When the value is less than 85%, the resulting polyisocyanate composition is colored. The processing time for it is 5 to 90 minutes, Preferably it is 5 to 60 minutes, More preferably, it is 5 to 30 minutes. Concentration of urea dimer in the concentrated liquid after treatment (concentration relative to the composition excluding diisocyanate monomer and solvent, ie, the total amount of biuret type polyisocyanate composition, urea dimer and multimer containing urea bonds) The content of urea dimer) is 0.5% by weight or less, preferably 0.3% by weight or less. When 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 treatment can be performed either batchwise or continuously. The liquid residence time in that case can be performed with substantially the same residence time because the decrease rate of the urea dimer is zero-order reactive. In addition, in this embodiment, although it is necessary to perform the process of the said process (c) under specific diisocyanate monomer density | concentration, after that, a diisocyanate monomer is removed as needed.

  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 thin film still is preferable. The scraping-type thin film distiller forcibly forms a thin film, efficiently evaporates the low-boiling diisocyanate monomer, and separates it from the polyisocyanate composition. When the reaction solution is fed to the scraping-type thin film distiller, the reaction solution is preferably degassed in advance. When a biuret type polyisocyanate composition is produced using water as a biuret agent, carbon dioxide is generated as a by-product gas, and a part of this carbon dioxide is dissolved in the reaction solution.

  When the reaction liquid containing dissolved gas is fed to the thin-film distiller that is a vacuum system, the dissolved gas is vaporized and foamed. At the time of vaporization and foaming, a part of the reaction liquid is scattered and attached as a mist to a cooler for condensing the diisocyanate monomer vapor. As a result, the reaction liquid is mixed into the separated and recovered diisocyanate monomer. This phenomenon becomes prominent when 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 using the polyisocyanate composition as a raw material has increased viscosity. Cause fluctuations. This phenomenon is remarkable when a by-product gas such as carbon dioxide gas is generated during the reaction for producing the polyisocyanate composition, such as a biuret type polyisocyanate composition using a biuret agent such as water. is there. The mixing concentration may reach several percent although it varies depending on conditions.

  The reaction solution is degassed by providing a tank having a degree of vacuum operated in substantially the same manner as the distiller, and dropping the reaction solution from the upper part of the tank. The reaction solution begins to degas as soon as it falls. When the reaction liquid that has reached the liquid level in the tank is not completely degassed, the liquid level becomes foamy and degassed. When the reaction liquid is fed to the tank liquid phase part, degassing may not be completed, which is not preferable. Although the tank can be provided with a stirrer, 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 distiller is preferably equal to or lower than the boiling point of the reaction solution. When the boiling point is exceeded, entrainment tends to occur, which is not preferable.

  Two scraping-type thin film distillers used for the removal of diisocyanate monomer and the like can be provided in series to remove the diisocyanate monomer in two stages. In that case, deaeration can be performed at each stage. The polyisocyanate composition thus obtained is substantially free of diisocyanate monomer. Usually, the diisocyanate monomer concentration is less than 1.5 wt%, preferably less than 1.0 wt%, more preferably less than 0.7 wt%, and even more preferably less than 0.3 wt%. The isocyanate group concentration of the polyisocyanate composition is 3 to 25% by weight, the viscosity at 25 ° C. is 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, turbidity may occur at low temperatures. Moreover, the transmittance | permeability of the obtained polyisocyanate composition is 85% or more.

  Hereinafter, the present embodiment will be described in more detail based on examples, but the present embodiment is not limited to the following examples.

(1) Measurement of concentration of urea dimer The urea dimer is represented by a general formula OCNR-NHC (= O) NH-RNCO. Each R is independently an aliphatic group or alicyclic group derived from diisocyanate. For example, in the case of hexamethylene diisocyanate, the area% of the peak having a peak top in the vicinity of a molecular weight of 310 was determined as the weight% of the urea dimer by the following gel permeation chromatograph (hereinafter “GPC”) analysis.
Carrier: Tetrahydrofuran (hereinafter “THF”) (flow rate: 0.6 ml / min)
Column: “TSKgel SuperH1000”, “TSKgel SuperH2000”, and “TSKgel SuperH3000” (all manufactured by Tosoh Corporation) 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 is defined as the content (% by weight) of the isocyanate group contained in the polyisocyanate, and was measured by the following method. 5-10 g of polyisoacinate was precisely weighed and dissolved in 20 ml of toluene, 20 ml of a 2N n-dibutylamine toluene solution was added to the resulting solution, and the reaction was allowed to stand at room temperature for 15 minutes. After completion of the reaction, the total amount of the obtained reaction mixture was back titrated with 1N hydrochloric acid using an APB-410 type automatic titrator manufactured by Kyoto Electronics Co., Ltd. to neutralize unreacted n-dibutylamine in the reaction mixture. The volume of 1N hydrochloric acid required (sample titration) was determined. On the other hand, the same operation as described above was performed except that polyisocyanate was not used, and the volume of 1N hydrochloric acid (blank titer) required for neutralization of unreacted n-dibutylamine was similarly determined.
Isocyanate group concentration (% by weight) = [{Blank titration (ml) −Sample titration (ml)} × 42 / {Sample weight (g) × 1000}] × 100

(3) Measurement of diisocyanate monomer concentration The root area of a 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. The percentage of the peak area relative to the total area of all peaks in the chromatogram was determined, and the value was defined as the diisocyanate monomer concentration (% by weight).
In addition, the measurement was performed for two types immediately after production and after sealing in a glass bottle under a nitrogen atmosphere and storing at 50 ° C./8 weeks (described as “after storage” in the table).
Judgment: ◎ Less than 0.3%
〇 0.3% or more and less than 0.7%
△ 0.7% or more and less than 1.0%
▲ 1.0% or more and less than 1.5%
× 1.5% or more

(4) Measurement of number average molecular weight A solution in which polyisocyanate was dissolved in THF (concentration: about 0.25 wt%) was subjected to 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 It measured at 25 degreeC using the VISCONIC * ED type | mold and E type | mold viscosity meter by Tokimec. In the measurement, a standard rotor (1 ° 34 ′ × R24) was used. The number of revolutions was set as follows.
100r. p. m. (If less than 128 mPa.s)
50r. p. m. (128 mPa.s or more and less than 256 mPa.s)
20r. p. m. (In the case of 256 mPa.s or more and less than 640 mPa.s)
10r. p. m. (In the case of 640 mPa.s or more and less than 1280 mPa.s)
5r. p. m. (When it is 1280 mPa.s or more and less than 2560 mPa.s)
2.5r. p. m. (2560 mPa.s or more and less than 5120 mPa.s)
1.0r. p. m. (5120 mPa.s or more and less than 10240 mPa.s)
0.5r. p. m. (In the case of 10240 mPa.s or more and less than 20480 mPa.s)

(6) Transmittance (coloring degree)
The transmittance at a cell length of 5 cm and a wavelength of 430 nm was measured with an ultraviolet-visible spectrophotometer (UV-160 manufactured by Shimadzu Corporation).
Judgment: ◎ 95% or more
* 90% or more and less than 95%
△ More than 85% and less than 90%
▲ 80% to less than 85%
× Less than 80%

[Example 1]
After making the inside of the flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen blowing tube into a nitrogen atmosphere, HDI: 700 parts by weight, trimethyl phosphate (described as “SP” in Table 1): 126 parts by weight, methyl Cellosolve acetate (described as “SA” in Table 1): 175 parts by weight, water: 9.4 parts by weight (HDI / water molar ratio = 8), and the liquid temperature was maintained at 160 ° C. for 1 hour. The obtained reaction liquid (unreacted diisocyanate monomer concentration: 70% by weight) was fed to a scraping-type thin film distiller at a vacuum degree of 8 Torr and a temperature of 160 ° C. at 500 g / Hr. The obtained biuret type polyisocyanate composition having a diisocyanate monomer concentration of 5% by weight was held at a liquid temperature of 140 ° C. for 30 minutes in a nitrogen atmosphere. This polyisocyanate composition is again fed into a scraping-type thin film distiller (vacuum degree 0.4 Torr, temperature 160 ° C.), diisocyanate monomer concentration 0.1% by weight (◎ judgment), transmittance 88% (Δ judgment), A biuret type polyisocyanate composition having a urea dimer concentration of 0.2% by weight or less and an isocyanate group concentration of 23.8% by weight was obtained.
The obtained biuret type polyisocyanate composition was sealed in a glass bottle under a nitrogen atmosphere, stored at 50 ° C. for 8 weeks, and the diisocyanate monomer concentration was measured and found to be 1.1% (（determination).

[Examples 2 to 10]
The same production method as in Example 1, except that trimethyl phosphate (described as “SP” in Table 1) and methyl cellosolve acetate (described as “SA” in Table 1) were used in the amounts shown in Table 1. A biuret type polyisocyanate composition was obtained. The results are shown in Table 1. All the biuret type polyisocyanate compositions had a urea dimer concentration of 0.2% by weight or less.

[Comparative Examples 1-8]
The same production method as in Example 1, except that trimethyl phosphate (described as “SP” in Table 1) and methyl cellosolve acetate (described as “SA” in Table 1) were used in the amounts shown in Table 1. A biuret type polyisocyanate composition was obtained. The results are shown in Table 1. All the biuret type polyisocyanate compositions had a urea dimer concentration of 0.2% by weight or less.

  The polyisocyanate composition according to the present invention is useful for paints, adhesives, sealing materials, waterproofing materials, foams, elastomers, fiber treatment agents and the like.

Claims (8)

  (A) a step of reacting at least one diisocyanate monomer selected from the group consisting of an aliphatic diisocyanate monomer and an alicyclic diisocyanate monomer with a biuret agent in the presence of a phosphate ester compound, (b) The step of adjusting the unreacted diisocyanate monomer concentration to 3 to 20% by weight, (c) the adjustment solution obtained in step (b) is 110 ° C. to 160 ° C., the cell length of the reaction solution is 5 cm, and the transmittance is 430 nm. A step of heating under a condition of maintaining 85% or more, and (d) a step of reducing the residual diisocyanate monomer concentration to less than 0.3%. In the step (a), a phosphate ester compound and an aliphatic diisocyanate compound For producing a biuret-type polyisocyanate composition, wherein the weight ratio is from 3: 100 to 18: 100   The method for producing a biuret type polyisocyanate composition according to claim 1, wherein the phosphate ester compound is trimethyl phosphate.   The method for producing a biuret-type polyisocyanate composition according to claim 1 or 2, wherein the diisocyanate monomer is hexamethylene diisocyanate.   The method for producing a biuret-type polyisocyanate composition according to any one of claims 1 to 3, wherein the biuretizing agent is water. The biuret type polyisocyanate composition according to any one of claims 1 to 4, wherein in the step (a), the diisocyanate monomer and the biuret agent are reacted in the presence of a solvent represented by the following general formula (1). Manufacturing method.

(Wherein R ¹ and R ² are alkyl groups or acyl groups having 1 to 4 carbon atoms, which may be the same or different, R ³ is a methyl group or hydrogen, and n is an integer of 1 to 2) is there.)   The method for producing a biuret type polyisocyanate composition according to any one of claims 1 to 5, comprising a step of removing the diisocyanate monomer by thin film distillation in the step (d).   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 distiller.   The step (a) is a continuous reaction in which the reaction liquid is further introduced into a pipe reactor after being stirred and homogenized, and the reaction is further advanced under an extrusion flow in the pipe reactor. The manufacturing method of biuret type polyisocyanate composition as described in 2.