STORAGE-STABLE POLYISOCYANATE COMPOSITION AND PREPARATION METHOD

Abstract

The present application provides a storage-stable polyisocyanate composition and a preparation method. The polyisocyanate composition is obtained by selecting one or more diisocyanate from aliphatic diisocyanates and alicyclic diisocyanates, and reacting same with an alcohol compound; the polyisocyanate composition contains an isocyanurate group, a uretdione group, a carbamate group, and an allophanate group; within the polyisocyanate composition, the molar ratio of the carbamate group/(uretdione group+isocyanurate group) is 0.01-0.2, and preferably 0.01-0.1. Compared to existing techniques, the present application has the advantage of a noticeable increase in system viscosity of uretdione polyisocyanate during storage. With the present application, by means of controlling the ratio of the carbamate group/(uretdione group+isocyanurate group) within the system, the increase in viscosity of a product during storage is inhibited, thereby improving the storage stability of the product.

Claims

1. A storage-stable polyisocyanate composition, which is obtained by reacting one or more diisocyanates selected from aliphatic diisocyanates and alicyclic diisocyanates, with an alcohol compound, and the polyisocyanate composition comprises an isocyanurate group, a uretdione group, a carbamate group and an allophanate group; in the polyisocyanate composition, a molar ratio of the carbamate group/(the uretdione group+the isocyanurate group) is 0.01-0.2.

2. The storage-stable polyisocyanate composition according to claim 1, wherein a molar ratio of the carbamate group/(the allophanate group+the carbamate group) is 0.01-0.4.

3. The storage-stable polyisocyanate composition according to claim 1 or 2, wherein an isocyanate group concentration is 16-24% by weight.

4. The storage-stable polyisocyanate composition according to claim 1, wherein the molar ratio of the carbamate group/(the uretdione group+the isocyanurate group) is 0.01-0.1; preferably, a molar ratio of the carbamate group/(the allophanate group+the carbamate group) is 0.01-0.3; preferably, an isocyanate group concentration is 20-23% by weight.

5. The storage-stable polyisocyanate composition according to claim 3, wherein a viscosity of the polyisocyanate composition at 25° C. is 100-1500 cp, preferably 130-1000 cp.

6. The storage-stable polyisocyanate composition according to any one of claims 1-5, wherein the alcohol compound has a relative molecular weight of 32-200, preferably, the alcohol compound is one or more of methanol, ethanol, n-propanol, isopropanol, n-butanol, n-hexanol, 2-ethyl-1-hexanol, 1-methoxy-2-propanol, ethylene glycol, propylene glycol, isomeric butanediol, hexylene glycols, caprylyl glycols, diethylene glycol, dipropylene glycol, 2-ethyl-1,3-hexanediol, 2,2,4-trimethylpentanediol, glycerol and trimethylolpropane.

7. The storage-stable polyisocyanate composition according to any one of claims 1-6, wherein the aliphatic diisocyanate and the alicyclic diisocyanate are an organic diisocyanate containing 4-20 carbon atoms in the carbon skeleton in addition to the NCO group.

8. The storage-stable polyisocyanate composition according to claim 7, wherein the organic diisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, cyclohexyl dimethylene diisocyanate, dicyclohexylmethane diisocyanate, norbornane dimethylene diisocyanate, cyclohexyl diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

9. The storage-stable polyisocyanate composition according to any one of claims 1-8, wherein after the polyisocyanate composition has been stored at less than or equal to 40° C. for 6 months, the product viscosity changes less than or equal to 10%.

10. A preparation method of the storage-stable polyisocyanate composition according to any one of claims 1-9, comprising: mixing and reacting the diisocyanate and the alcohol compound, and controlling a reaction temperature to be 50-160° C.; controlling a reaction time to be 0.5-4 hours; then adding a tertiary phosphine catalyst, and controlling a reaction temperature to be 60-120° C. and a reaction time to be 1-12 hours; or, mixing and reacting the diisocyanate and a tertiary phosphine catalyst, and controlling a reaction temperature to be 50-150° C.; controlling a reaction time to be 0.5-12 hours; then adding the alcohol compound, and controlling a reaction temperature to be 60-120° C. and a reaction time to be 1-3 hours.

11. The preparation method of the storage-stable polyisocyanate composition according to claim 10, wherein the tertiary phosphine catalyst has the following structural formula: ##STR00004## wherein R.sub.1, R.sub.2 and R.sub.3 are independently selected from an aliphatic substituent or an aromatic substituent.

12. The preparation method of the storage-stable polyisocyanate composition according to claim 10, wherein when the diisocyanate and the alcohol compound are mixed and reacted, the reaction temperature is controlled to be 50-150° C.

13. The preparation method of the storage-stable polyisocyanate composition according to claim 10, wherein when the diisocyanate and the alcohol compound are mixed and reacted, the reaction time is controlled to be 1 hour; preferably, after adding the tertiary phosphine catalyst, the reaction temperature is controlled to be 60-100° C.; preferably, after adding the tertiary phosphine catalyst, the reaction time is controlled to be 1-8 hours.

14. The preparation method of the storage-stable polyisocyanate composition according to claim 10, wherein when the diisocyanate and the tertiary phosphine catalyst are mixed and reacted, the reaction temperature is controlled to be 50-80° C.; preferably, when the diisocyanate and the tertiary phosphine catalyst are mixed and reacted, the reaction time is controlled to be 1-10 hours; preferably, after adding the alcohol compound, the reaction temperature is controlled to be 80-100° C.; preferably, after adding the alcohol compound, the reaction time is controlled to be 1-2 hours.

Description

DETAILED DESCRIPTION

[0040] Although the method provided in the present application is further illustrated through embodiments hereinafter, the present application is not limited to the listed embodiments, and further comprises any other known variations within the scope of the claims of the present application. The specific application of the present application is not limited to the applications mentioned in the embodiments, and the simple variations can be made for the present application by those skilled in the art using conceptions in the present application without departing from the protection scope of the present application.

[0041] The following testing methods are used in embodiments of the present application.

[0042] (1) Determination of a GPC reaction conversion rate

[0043] The gel chromatography technology (LC-20AD/RID-10A, chromatographic column: MZ-Gel SDplus 10E3A 5 μm (8.0*300 mm), MZ-Gel SDplus 500A 5 μm (8.0*300 mm) and MZ-Gel SDplus 100A 5 μm (8.0*300 mm) connected in series, Shimadzu; mobile phase: tetrahydrofuran; flow rate: 1.0 mL/min; analysis time: 40 min, temperature of chromatographic column: 35° C.) was used to quantify the raw material of isocyanate, the area normalization method was used to determine the area of polymers and monomers in the system, and the GPC reaction conversion rate (%)=S (a monomer peak area)/S (a sum of each component peak area)*100%.

[0044] (2) An isocyanate group concentration (NCO group content) was determined according to the standard GB/T 12009.4.

[0045] (3) Viscosity determination method: A dynamic viscosity was determined at 25° C. using a BrookField DV-I Prime viscometer with an S21 rotor.

[0046] (4) Determination of a carbamate group/(a uretdione group+an isocyanurate group)

[0047] This molar ratio was denoted as Molar Ratio 1. The determination method adopted the .sup.13C-NMR nuclear magnetic resonance method. The instrument used was a Bruker 400 MHz instrument, the sample concentration was 50% by weight (CDCl.sub.3 solution), and the determination condition was 100 MHz.

[0048] The calculation method of the molar ratio was that:Molar Ratio 1=the signal area at around 156 ppm/(the signal area at around 149 ppm/3+the signal area at around 158 ppm/2).

[0049] (5) Determination of a carbamate group/(carbamate+allophanate):

[0050] This molar ratio was denoted as Molar Ratio 2. The determination method adopted the H-NMR nuclear magnetic resonance method, the instrument used was a Bruker 400 MHz instrument, the sample concentration was 5% by weight (CDCl.sub.3 solution), and the determination condition was 400 MHz.

[0051] The calculation method of the molar ratio was that:Molar Ratio 2=the signal area at around 4.9 ppm/(the signal area at around 8.9 ppm+the signal area at around 4.9 ppm).

[0052] (6) Curing performance

[0053] The coating composition was coated on tinplate, placed for 15 min, baked at 80° C. for 60 min, and placed at room temperature for 15 min. The adhesion was tested by the hundred-cell method, and the lower the adhesion test value, the better the curing performance.

[0054] In the following examples, the information of the raw materials used is as follows:

[0055] hexamethylene diisocyanate: Wanhua Chemical, purity>99%;

[0056] 2-ethyl-1,3-hexanediol: Aladdin reagent, purity>99%;

[0057] tri-n-octylphosphine: Sigma reagent, purity>95%;

[0058] diisooctyl phosphate: Aladdin reagent, purity>99%;

[0059] tri-n-butylphosphine: Aladdin reagent, purity>95%; and

[0060] methyl p-toluenesulfonate: Aladdin reagent, purity>99%.

[0061] Other raw materials and reagents can be obtained through commercial channels unless otherwise specified.

[0062] Unless otherwise specified in the following examples and comparative examples, the reaction solution was kept under the protection of dry nitrogen before the reaction, during the catalyst addition and during the entire reaction process. All percentages are by mass unless otherwise specified.

Example 1

[0063] To hexamethylene diisocyanate (HDI) with a total mass M of 1000 g, 15 g of 2-ethyl-1,3-hexanediol was added under stirring at 50° C., and reacted for 1 hour to perform a carbamate-forming reaction. The reactor was controlled at a temperature of 60° C., and added with 2.5 g of tri-n-octylphosphine. The gel chromatography was used to quantitatively monitor the ratio of the consumed mass M1 of HDI to the total mass M of HDI added in the reaction system (i.e. the GPC reaction conversion rate). When the GPC reaction conversion rate was 30-65%, 2.2 g of diisooctyl phosphate was added to terminate the reaction. A distillation was performed to remove the unreacted HDI in the reaction system using a two-stage film evaporator at 140° C. and under 0.3 mbar, so as to obtain a polyisocyanate product containing uretdione groups. The indexes of each product prepared under different GPC reaction conversion rates are separately shown in Table 1.

TABLE-US-00001 TABLE 1 Various index parameters of the polyisocyanate compositions in Example 1 GPC reaction Initial Viscosity Homogeneity conversion Isocyanate group Molar Molar viscosity/cp after 6 after 6 rate/% concentration/% Ratio 1 Ratio 2 (25° C.) months/cp months 1-a 30 22.5 0.38 0.4 75 98 turbid 1-b 40 22 0.25 0.3 95 120 turbid 1-c 43 21.8 0.20 0.26 110 115 normal 1-d 45 21.6 0.10 0.23 124 131 normal 1-e 50 21.2 0.08 0.17 180 190 normal 1-f 55 21 0.01 0.011 464 480 normal 1-g 65 20.4 0.005 0.008 1145 4986 normal

Example 2

[0064] To hexamethylene diisocyanate (HDI) with a total mass M of 1000 g, 2.5 g of tri-n-octyl phosphine was added under stirring at 60° C., and the gel chromatography was used to quantitatively monitor the ratio of the consumed mass M1 of HDI to the total mass M of HDI added in the reaction system (i.e. the GPC reaction conversion rate). When the GPC reaction conversion rate was 50%, 2.2 g of diisooctyl phosphate was added to terminate the reaction. The system was heated to 80° C. and added with 15 g of 2-ethyl-1,3-hexanediol, and continued to react for 0.5-4 hours. Distillations were separately performed to remove the unreacted HDI in the reaction system using a two-stage film evaporator at 140° C. and under 0.3 mbar, so as to obtain polyisocyanate products containing uretdione groups. The indexes of each product prepared under different reaction time are separately shown in Table 2.

TABLE-US-00002 TABLE 2 Various index parameters of the polyisocyanate compositions in Example 2 Later-stage Initial Viscosity Homogeneity reaction Isocyanate group Molar Molar viscosity/cp after 6 after 6 time/h concentration/% Ratio 1 Ratio 2 (25° C.) months/cp months 2-a 0.5 22 0.20 0.5 160 173 inhomogeneous 2-b 1 21.8 0.16 0.4 180 190 normal 2-c 1.5 21.65 0.08 0.28 192 201 normal 2-d 2 21.6 0.02 0.02 220 240 normal 2-e 4 21.3 0.005 0.007 240 1529 normal

[0065] The curing performance of each polyisocyanate composition in Example 2 was tested, and the testing method was as follows: a hydroxy acrylic resin (Tongde AC1100B, solid content 60%, hydroxyl value 86 mg/g) was respectively mixed with the above polyisocyanate compositions containing uretdione groups at a molar ratio of NCO/OH=1:1, and diluted to 50% with a butyl acetate solven, and the coating film was evaluated. The performance test results are shown in the table below.

TABLE-US-00003 TABLE 3 Evaluation table of the coating film test in Example 2 Product No. Adhesion grade 2-a 3 2-b 2 2-c 2 2-d 1 2-e 1

Example 3

[0066] To 1000 g of hexamethylene diisocyanate (HDI), 5 g of 1,3-butanediol was added at 60° C. and reacted for 1 hour, and then 3 g of tri-n-butylphosphine was added as a catalyst, after a reaction time of 4 hours, under being quantitatively monitored using the gel chromatography, the ratio of the consumed mass M1 of HDI to the total mass M of HDI added in the reaction system was 55%. 2.8 g of methyl p-toluenesulfonate was added and heated for 1 hour to 80° C., and then the reaction was terminated. After termination, 5 g of 1,3-butanediol was added, and continued to react for 1 hour. A film distillation was performed at 140° C. and under 0.3 mbar, so as to obtain a polyisocyanate composition product 3-a containing uretdione groups, of which the indexes are shown in Table 4.

Comparative Example 1

[0067] This comparative example was performed with reference to the example 1 in the patent literature CN1334264A, of which the process was described below. To 1000 g of hexamethylene diisocyanate (HDI), 10 g of 1,3-butanediol and 3 g of tri-n-butylphosphine were added at 60° C. as catalysts. After a reaction time of 4 hours, under being quantitatively monitored using the gel chromatography, the ratio of the consumed mass M1 of HDI to the total mass M of HDI added in the reaction system was 55%. 2.8 g of methyl p-toluenesulfonate was added and heated for 1 hour to 80° C., and then the reaction was terminated. A film distillation was performed at 140° C. and under 0.3 mbar, so as to obtain a product D1 containing uretdione groups, of which the indexes are shown in Table 4.

Comparative Example 2

[0068] This comparative example was performed with reference to the technical solution in the patent literature DE-A 1670720, of which the specific method was described below. To 1000 g of hexamethylene diisocyanate (HDI), 3 g of tri-n-butylphosphine was added at 60° C. as a catalyst. After a reaction time of 4 hours, under being quantitatively monitored using the gel chromatography, the ratio of the consumed mass M1 of HDI to the total mass M of HDI added in the reaction system was 55%. 2.8 g of methyl p-toluenesulfonate was added and heated for 1 hour to 80° C., and then the reaction was terminated. A film distillation was performed at 140° C. and under 0.3 mbar, so as to obtain a product D2 containing uretdione groups, of which the indexes are shown in Table 4.

TABLE-US-00004 TABLE 4 Various index parameters of the polyisocyanate compositions in Example 3 and Comparative Examples 1 and 3 Initial Viscosity Isocyanate group Molar Molar viscosity/cp after 6 Homogeneity concentration/% Ratio 1 Ratio 2 (25° C.) months/cp after 6 months 3-a 21.8 0.08 0.03 162 170 normal D1 21.8 0.005 0.02 168 573 normal D2 22 / / 148 4528 normal

[0069] It can be seen from the performance test results of the above examples and comparative examples that:

[0070] In the products of low-viscosity system, when the absolute content of carbamate was relatively high in the system, that is, when Molar Ratio 1 was more than 0.2, although the viscosity of the low-viscosity system was inhibited from increasing, the system was prone to a turbidity condition during storage due to the poor compatibility of carbamate structure in the system, and for example, samples in 1-a and 1-b had such circumstance; although the sample in 2-a did not exhibit the significant turbidity condition, it had exhibited a condition of poor light transmittance and overall non-uniformity which could even be observed by naked eye, resulting from that Molar Ratio 1 was close to the critical value, and Molar Ratio 2 was more than 0.4.

[0071] When the absolute content of carbamate was relatively low, that is, when Molar Ratio 1 was less than 0.01, although Molar Ratio 2 satisfied the requirement, the absolute content of carbamate was low in the system, exhibiting a weak effect of inhibiting the viscosity of the low-viscosity system from increasing, and the viscosity of the system was still prone to increase, as shown in Comparative Example 1. And for Comparative Example 2, the reaction raw materials included no alcohol compound, and the product included no carbamate structure absolutely, and the increase trend of viscosity was more significant in the system.