阅读说明：本技术 一种多异氰酸酯组合物及其制备方法 (Polyisocyanate composition and preparation method thereof ) 是由 孙立冬 王少华 孙淑常 尚永华 史培猛 胡浩 王暖程 吴永康 于 2020-12-09 设计创作，主要内容包括：本发明提供一种多异氰酸酯组合物,其中三分子聚合物占所述多异氰酸酯组合物质量的60～80％,其含有下述式(Ⅰ)所示异氰脲酸酯三聚体和式(Ⅱ)、式(Ⅲ)所示的亚氨基噁二嗪二酮三聚体本发明可在不使用特殊催化剂的情况下以较高的转化率制备得到低粘多异氰酸酯组合物。(The invention provides a polyisocyanate composition, wherein a trimolecular polymer accounts for 60-80% of the mass of the polyisocyanate composition, and the polyisocyanate composition contains isocyanurate tripolymer shown in a formula (I) and iminooxadiazinedione tripolymer shown in a formula (II) and a formula (III))

1. A polyisocyanate composition comprising a polyisocyanate having an isocyanurate structure obtained by trimerizing an aliphatic (cyclo) isocyanate monomer,

the composition is characterized in that the composition contains 60-80% by mass of trimer, wherein the composition contains isocyanurate trimer A shown in the following formula (I) and iminooxadiazinedione trimer B, C shown in the formulas (II) and (III),

in the formula, R₁And R₂Independently a C1-10 aliphatic (cyclo) hydrocarbon group.

2. The polyisocyanate composition of claim 1 wherein trimers constitute 65 to 75% by mass of the polyisocyanate composition, and wherein isocyanurate trimer A constitutes 1 to 10% by mass of the polyisocyanate composition.

3. Polyisocyanate composition according to any one of claims 1-2, characterized in that the molar amount X of isocyanurate trimer a and the molar amount Y, Z of iminooxadiazinedione trimer B, C satisfy: (Y + Z)/(X + Y + Z) is 0.01 to 0.2 inclusive.

4. A process for the preparation of the polyisocyanate composition of claims 1 to 3, comprising the steps of:

s1: under the protection of nitrogen, carrying out trimerization reaction on an aliphatic (cyclo) diisocyanate monomer under the action of a trimerization catalyst;

s2: when the reaction conversion rate reaches 10-30%, adding aliphatic (cyclo) monoisocyanate accounting for 3-20 wt% of the initial monomer mass into a reaction system;

s3: when the reaction is carried out to a proper conversion rate, adding a terminator into the reaction system to stop the reaction;

s4: the unreacted isocyanate monomer is separated off.

5. The method according to claim 4, wherein the (cyclo) aliphatic diisocyanate monomer is selected from the group consisting of tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, and lysine diisocyanate.

6. The process according to claim 4, wherein the (cyclo) aliphatic monoisocyanate is selected from the group consisting of octyl 1-isocyanate, hexyl isocyanate, butyl isocyanate, cyclopentyl isocyanate, isopropyl isocyanate, benzyl isocyanate and allyl isocyanate.

7. The process according to any one of claims 4to 6, wherein the reaction temperature is 50 to 80 ℃, preferably 60 to 70 ℃.

8. The method according to any one of claims 4to 7, wherein the trimerization catalyst is a quaternary ammonium salt and/or a quaternary ammonium base catalyst, preferably selected from tetramethylammonium acetate, tetrabutylammonium acetate, choline chloride, N- (2-hydroxypropyl) -N, N, N-trimethylammonium salt of 2-ethylhexanoic acid, N, N, N-trimethylbenzylammonium hydroxide.

9. The method according to claim 4, wherein in step S3, the reaction is terminated when the reaction conversion rate reaches 40 to 60%; the terminating agent is an acidic compound, preferably one or more of hydrochloric acid, phosphoric acid, dibutyl phosphate, di (2-ethylhexyl) phosphate, dicyclohexyl phosphate, p-toluenesulfonic acid, benzenesulfonic acid, alkylbenzene sulfonic acid, acetyl chloride and benzoyl chloride.

10. The method according to claim 4, wherein the isocyanate monomer is separated by two-stage thin film evaporation at 140 to 170 ℃ and 50 to 200Pa in S4; the content of unreacted isocyanate monomer in the polyisocyanate obtained after two-stage film evaporation is less than 0.2 percent.

Technical Field

The invention provides a polyisocyanate composition and a preparation method thereof.

Background

Isocyanurate-containing polyisocyanate compositions derived from aliphatic diisocyanates are widely used in the high-end fields of paints for automobiles, interior and exterior buildings, home appliances, and the like, particularly, automotive refinishs, varnishes, and the like, because of their excellent weather resistance and heat resistance. In recent years, as environmental protection requirements of governments have been increasing, polyisocyanates used as curing agents have been developed toward lower viscosity in order to reduce the use of organic solvents in coating compositions during application.

The processes which have been disclosed to date for preparing low-viscosity polyisocyanate compositions containing isocyanurate structures have mainly been to reduce the reaction conversion to increase the low-molecular polymer content and to introduce low-viscosity modifying components by modifying means.

In the technical field, the isocyanurate type polyisocyanate in practical application generally refers to a mixture of a three-molecule polymer (hereinafter referred to as trimer), a five-molecule polymer, a seven-molecule polymer and a multi-molecule polymer (polymer having a degree of polymerization greater than seven) obtained by trimerization of isocyanate monomers. Generally, the higher the content of trimer having a single ring structure, the lower the viscosity of the polyisocyanate composition.

CN107868226A discloses a process for the preparation of narrow distribution diisocyanate trimers, in which a low-viscosity polyisocyanate composition having a trimer content of 65% to 90% is prepared by means of a heterogeneous trimerization reaction, but the trimerization catalyst used is an N-alkylated solid catalyst, the preparation of which is complicated.

U.S. Pat. No. 4,4801663 describes a low-viscosity polyisocyanate composition with a high proportion of isocyanurate single ring structure, wherein the proportion of isocyanurate single ring polymer is as high as 70-75%, but the reaction conversion rate can only reach 12-21%, and the total reaction yield is obviously reduced. This process requires the removal of large amounts of unreacted monomers from the final reaction product, which adds significantly to the cost of the process.

CN1757639A discloses a method for preparing a low viscosity polyisocyanate containing iminooxadiazinedione groups, wherein, for an aliphatic diisocyanate polymer containing not less than three NCO groups, the iminooxadiazinedione structure has the lowest viscosity, and the viscosity of the polyisocyanate composition can be reduced by introducing the iminooxadiazinedione structure, but a (hydro poly) fluoride needs to be used as a catalyst in the introduction of the iminooxadiazinedione structure, a higher proportion of HF exists in the industrial waste gas thereof, and the catalyst solution is corrosive.

US5454344A discloses a polyisocyanate composition and a coating composition and an adhesive composition using the same, which achieve a reduction in product viscosity by controlling the content of isocyanurate ring trimer in the composition to less than 60% and the content of uretdione dimer to more than 10%, have a low uretdione molecular weight and a low self-viscosity, and are effective in reducing the viscosity of the composition, but uretdione has a linear structure, is poor in crosslinkability and thermal stability, and has a case where the content of monomer increases during storage.

As is apparent from the prior art, the presently disclosed techniques for preparing low-viscosity isocyanurate type polyisocyanates require modification by introducing iminooxadiazinedione, uretdione, or reduction of reaction conversion or use of a special catalyst.

Disclosure of Invention

An object of the present invention is to provide an isocyanurate-type polyisocyanate composition which is obtained without lowering the reaction conversion or using a specific catalyst while having a low viscosity.

It is another object of the present invention to provide a method for preparing an aliphatic polyisocyanate composition.

As a result of intensive studies, it has been found that addition of monoisocyanate in the trimerization process using a diisocyanate monomer as a raw material can increase the content of trimer in the system, reduce the viscosity of the product, and allow the reaction to proceed at a high conversion rate. The present invention has been completed based on the above findings.

A low-viscosity polyisocyanate composition comprises a polyisocyanate having an isocyanurate structure obtained by trimerization of (cyclo) aliphatic isocyanate monomers, wherein the polyisocyanate composition contains 60 to 80% by mass of a trimer, and the trimer contains, in addition to diisocyanate trimers represented by formulas (1) and (2), an isocyanurate trimer A represented by formula (I) below and an iminooxadiazinedione trimer B, C represented by formulas (II) and (III) below.

In the formula, R1 and R2 are independently an aliphatic (cyclo) hydrocarbon group having 1 to 10 carbon atoms, and are preferably one of n-propyl, n-butyl, n-pentyl, n-hexyl, and n-octyl, and more preferably n-hexyl.

In the polyisocyanate composition of the present invention, the amount of trimer is 65 to 75% by mass of the polyisocyanate composition, and the amount of trimer A is 1 to 10% by mass of the polyisocyanate composition.

Further, in the polyisocyanate composition, the molar amount X of isocyanurate trimer a and the molar amount Y of trimer B and the molar amount Z of trimer C satisfy ((Y + Z)/(X + Y + Z)) of 0.01 to 0.2.

The amount and ratio of the structure A, B, C in the polyisocyanate composition can be controlled, for example, by adding monoisocyanate to the diisocyanate trimerization process and by controlling the type of trimerization catalyst.

The invention also provides a preparation method of the polyisocyanate composition. In one embodiment, the method comprises the steps of:

s1: under the protection of nitrogen, carrying out trimerization reaction on diisocyanate monomer under the action of a trimerization catalyst;

s2: when the reaction conversion rate reaches 10-30%, adding 3-20 wt% of monoisocyanate relative to the initial monomer mass into the reaction system;

s3: when the reaction is carried out to a proper conversion rate, adding a terminator into the reaction system to stop the reaction; and

s4: the unreacted isocyanate monomer was separated off by two-stage thin-film evaporation.

In the preparation method of the present invention, the diisocyanate monomer is selected from tetramethylene diisocyanate, pentamethylene diisocyanate, Hexamethylene Diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), or Lysine Diisocyanate (LDI), preferably selected from Hexamethylene Diisocyanate (HDI) and isophorone diisocyanate (IPDI).

In the method of the present invention, the monoisocyanate monomer is selected from the group consisting of octyl 1-isocyanate, hexyl isocyanate, butyl isocyanate, cyclopentyl isocyanate, isopropyl isocyanate, benzyl isocyanate, allyl isocyanate, preferably selected from hexyl isocyanate and butyl isocyanate.

In the preparation method, the reaction temperature in the reaction steps S1, S2 and S3 is 50-80 ℃, and more preferably 60-70 ℃.

In the preparation method of the invention, the trimerization catalyst is quaternary ammonium salt and/or quaternary ammonium base catalyst capable of promoting isocyanuric acid esterification reaction and iminooxadiazine diketonization reaction at the same time, and preferably one or more of tetramethylammonium acetate, tetrabutylammonium acetate, choline chloride, 2-ethylhexanoic acid-N- (2-hydroxypropyl) -N, N, N-trimethylammonium salt or N, N, N-trimethylbenzylammonium hydroxide. The amount of the catalyst used is 10 to 1000ppm, more preferably 20 to 500ppm, based on the mass of the starting diisocyanate monomer.

According to the preparation method disclosed by the invention, in the step S3, the reaction is stopped when the reaction conversion rate (the total conversion rate of diisocyanate monomer and monoisocyanate monomer) reaches 40-60%.

In the production method of the present invention, the terminating agent for stopping the reaction in the step S3 is an acidic compound, preferably one or more of hydrochloric acid, phosphoric acid, dibutyl phosphate, di (2-ethylhexyl) phosphate, dicyclohexyl phosphate, p-toluenesulfonic acid, benzenesulfonic acid, alkylbenzenesulfonic acid, acetyl chloride, benzoyl chloride, and further preferably dibutyl phosphate and/or di (2-ethylhexyl) phosphate.

In the preparation method, in the step S4, the temperature of the two-stage film evaporation is preferably 140-170 ℃, and the pressure is preferably 50-200 Pa.

Further, the content of unreacted isocyanate monomer in the polyisocyanate obtained after two-stage film evaporation is less than 0.2%.

The invention has the beneficial effects that:

compared with other prior art, the invention can obtain the low-viscosity isocyanurate type polyisocyanate composition with higher trimer content at higher conversion rate under the condition of not using special catalyst.

Detailed Description

In order to better understand the present invention, the following detailed description of the technical solution of the present invention is provided with reference to specific examples. The following examples are intended to illustrate the invention, but the invention is not limited to the following examples.

< measurement of product viscosity >

The viscosity of the products of the examples and comparative examples was measured using a Brookfield RC/S rheometer, rotor model CC-40, water bath thermostatted, controlled at 25. + -. 0.1 ℃. The shear rate is 25S-1 to 250S-1.

< determination of trimer content in product and reaction conversion >

The trimer content and the reaction conversion in the examples and comparative examples were measured by gel chromatography. The Gel chromatography test method is implemented by using LC-20AD/RID-10A, and the chromatographic columns are MZ-Gel SDplus 10E3A 5 μm (8.0 × 300mm), MZ-Gel SDplus 500A 5 μm (8.0 × 300mm), MZ-Gel SDplus 100A 5 μm (8.0 × 300mm) in series and Shimadzu;

mobile phase: tetrahydrofuran;

flow rate: 1.0 mL/min;

analysis time: 40 min;

temperature of the column: 35 ℃ is carried out.

< determination of the trimer A, B, C content in the product >

The content of the trimer A, B, C in the polyisocyanate compositions obtained in the examples and comparative examples was measured by high performance liquid chromatography-tandem high resolution mass spectrometry.

UPLC-HRMS device: ultimate 3000-Thermo Q active Focus

A chromatographic column: agilent extended C18 RRHD 2.1 × 100mm 1.8um

Scanning range: 100-1500m/z

Mobile phase: a: pure water, B: pure acetonitrile

< NCO content (NCO%) >

The NCO content (% by mass) was determined by neutralizing the isocyanate group in the measurement sample with an excess of 2N amine and then back-titrating with 1N hydrochloric acid.

< determination of the Mass concentration of monomers >

A20 mL sample bottle was placed on an electronic balance, and 1g of the sample was precisely weighed and added. Then, 0.03 to 0.04g of nitrobenzene (internal standard solution) was precisely weighed and added to the sample bottle. Finally, 9mL of ethyl acetate was added to the sample bottle, and the cap was closed. Then, the mixture was sufficiently stirred to prepare a measurement sample. The measurement sample was subjected to a hue chromatography under the following conditions to quantify the amount of the monomer.

The device comprises the following steps: shimadzu corporation, "GC-8A"

Column: silicone OV-17, product of Xinhe chemical Co., Ltd "

Column oven temperature: 120 deg.C

Injection/detector temperature: 160 deg.C

[ examples 1 to 6 ]

Examples 1-6 general procedure for the preparation of aliphatic isocyanurate polyisocyanate compositions is as follows:

800g of aliphatic diisocyanate monomer were heated in a water bath at 70 ℃ for 1h under nitrogen protection. Then, 0.6g (150ppm) of a 20 wt% isooctanol solution of N, N, N-trimethylbenzylammonium hydroxide was added thereto, and the reaction temperature was controlled at 70 ℃; when the reaction conversion rate reaches 20 percent, adding a certain amount of aliphatic monoisocyanate into the reaction liquid, and continuing to react at 70 ℃; when the final conversion (conversion of total monomers) reached 42%, 0.16g (200ppm) of dibutyl phosphate was added to terminate the reaction. Next, the polyisocyanate composition having an isocyanate monomer content of less than 0.2% was obtained by distilling twice at 150 ℃ and 0.4Torr using a thin film evaporator.

Analyzing the total content of the tripolymer of the composition product obtained by separation by using a gel chromatography technology, analyzing the content of the tripolymer A, B, C by using a liquid chromatography-mass spectrometry combined technology, and measuring the viscosity of the product at 25 ℃ by using a Brookfield RC/S rheometer.

The reaction parameters, material ratios and reaction results are shown in table 1.

[ COMPARATIVE EXAMPLES 1 to 2 ]

Comparative examples 1-2 were carried out without the step of adding monoisocyanate when the reaction conversion rate reached 20%, and the other steps were exactly the same as in examples. The reaction parameters, material ratios and reaction results are shown in table 1.

TABLE 1 polyisocyanate composition raw materials, parameters and reaction results

*: the product-based n-butyl acetate solution had a solids content of 70%.

From the experimental results, it is understood that an isocyanurate-type low-viscosity polyisocyanate composition having a high three-molecular polymer content can be obtained at a high conversion rate by the method for preparing a polyisocyanate provided by the present invention.

Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.