A dicyclohexylmethane diisocyanate composition and a thermoplastic polyurethane elastomer

Abstract

The application discloses a kind of dicyclohexyl methane diisocyanate compositions and thermoplastic polyurethane elastomer.The isomer 2,4'-dicyclohexyl methane diisocyanate (2,4'-HMDI) content in the dicyclohexyl methane diisocyanate composition (HMDI) is <2%wt, and the F value of the HMDI composition ranges from 0.23 to 0.64.The thermoplastic polyurethane elastomer prepared by using the dicyclohexyl methane diisocyanate composition provided by the application has very high light transmittance and very strong tensile strength.

Description

Technical Field

[0001] The present invention provides a dicyclohexylmethane diisocyanate (HMDI) composition, and the thermoplastic polyurethane elastomer prepared using the HMDI composition has extremely high light transmittance and extremely low haze. Background Technology

[0002] Dicyclohexylmethane diisocyanate (HMDI) is an aliphatic isocyanate. Because it lacks a benzene ring in its structure, it exhibits excellent weather resistance and can be used to prepare high-grade polyurethane materials with light stability, weather resistance, and excellent mechanical properties, such as TPU, elastomers, waterborne polyurethane dispersions, and UV resins.

[0003] Especially in the field of TPU applications, with the gradual development of TPU substrates for automotive coatings in recent years, the performance requirements for TPU particles are getting higher and higher. For example, patent CN116162220A provides a high-transparency, high-resilience, flame-retardant thermoplastic polyurethane elastomer and its preparation method and application. It has high transparency, high resilience and flame-retardant properties, and is especially suitable for automotive coating TPU substrates.

[0004] The industry standard HG / T 6064-2022 discloses that HMDI contains two isomers: 2,4'-HMDI and 4,4'-HMDI. Furthermore, 4,4'-HMDI also contains three different isomers: cis,cis'-HMDI, cis,trans'-HMDI, and trans,trans'-HMDI.

[0005] Patent CN116023627A provides an HMDI composition containing both 2,4'-HMDI and 4,4'-HMDI, which is mainly used in the 3D printing field. However, this specification of product does not perform well in the TPU car coating field.

[0006] However, in the field of TPU applications, with the gradual development of automotive coating TPU substrates in recent years, the performance requirements for TPU particles are getting higher and higher. For example, patent CN116162220A provides a high transparency, high resilience and flame retardant thermoplastic polyurethane elastomer and its preparation method and application, which has high transparency, high resilience and flame retardant properties, and is especially suitable for automotive coating TPU substrates.

[0007] Patent CN111909504A discloses a polyurethane flame-retardant film for invisible car wraps, its preparation method and uses. By introducing polyvinylidene chloride and chlorinated polyethylene through blending modification, the extruded film has certain flame-retardant properties, but the tensile strength and transparency of the film are reduced.

[0008] Therefore, it is of great significance to develop a dicyclohexylmethane diisocyanate composition that can produce thermoplastic polyurethane elastomers with extremely high light transmittance and extremely high tensile strength. Summary of the Invention

[0009] In view of the above-mentioned problems in the prior art, the present invention provides a dicyclohexylmethane diisocyanate composition, and the thermoplastic polyurethane elastomer made from this HMDI composition has extremely high light transmittance and extremely high tensile strength.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] A dicyclohexylmethane dicyanate (HMDI) composition, wherein the isomer 2,4'-dicyclohexylmethane dicyanate composition

[0012] The cyclohexylmethane diisocyanate (2,4'-HMDI) content is <2%wt, and the F value of the HMDI composition is in the range of 0.23-0.64, preferably 0.26-0.59, and more preferably 0.30-0.54.

[0013] The F-value of the dicyclohexylmethane diisocyanate composition of the present invention is calculated using the following formula:

[0014] F = (0.5 × cis, trans'-HMDI content %wt + trans, trans'-HMDI content %wt) ÷ 100%wt.

[0015] The dicyclohexylmethane diisocyanate composition of the present invention, wherein the specific structure of cis,trans-HMDI in the dicyclohexylmethane diisocyanate composition is as follows:

[0016] The specific structure of trans,trans-HMDI in the dicyclohexylmethane diisocyanate composition of this invention is as follows:

[0017]

[0018] The preparation method of the HMDI composition described in this invention is not specifically required, and the HMDI composition can be obtained in any feasible manner.

[0019] Method 1: The HMDI composition of this invention is prepared by controlling the isomer content in the raw materials. The isomers in the HMDI composition are derived from the raw material dicyclohexylmethanediamine (HMDA), or even from the raw material diphenylmethanediamine (MDA) of HMDA. The preparation of the HMDI composition of this invention can be achieved by adjusting the 2,4'-MDA content in MDA and the t,t'-HMDA content in HMDA. The specific operation can refer to the methods disclosed in the prior art, such as the method for adjusting 2,4'-HMDA in HMDA disclosed in patent CN101429139A, and the method for adjusting t,t'-HMDA also mentioned in patent CN103265438A.

[0020] Method 2: The dicyclohexylmethane dicyanate composition of this invention is prepared from existing dicyclohexylmethane dicyanate products with different isomer compositions through a separation process. In the subsequent separation process of preparing HMDI products from HMDA, the content of different isomers in the HMDI composition is adjusted by different separation processes such as crystallization and distillation.

[0021] Method 3: The dicyclohexylmethane dicyanate composition of this invention is prepared by mixing different isomers. For example, the corresponding isomers can be added to a conventional HMDI composition.

[0022] The above three methods can be used in combination or individually. This invention does not limit the method of obtaining the HMDI composition.

[0023] The content of relevant isomers in the dicyclohexylmethane diisocyanate composition described in this invention was tested using the method provided in HG / T6064-2022.

[0024] The HMDI composition described in this invention can be used in the field of thermoplastic polyurethane elastomers (TPU), and the resulting thermoplastic polyurethane elastomers have extremely high light transmittance and extremely low haze.

[0025] A TPU comprising the following components:

[0026] (1) The HMDI composition of the present invention is 25-45 wt%;

[0027] (2) At least one polyol, 40-65 wt%;

[0028] (3) At least one chain extender, 4-25 wt%;

[0029] (4) Catalyst 0.10-0.2 wt%.

[0030] The polyols described in this invention are selected from one or more of conventional polyester polyols, polylactone polyols, polyether polyols, or polycarbonate polyols, preferably one or more of polycaprolactone diol, polycarbonate diol, and polytetramethylene ether diol. The number average molecular weight of the polyols is 700-4000 g / mol, preferably 1000-3000 g / mol. The specific preparation method can be referred to the method mentioned in patent CN116162220A.

[0031] The conventional polyester polyols described in this invention refer to polyester polyols obtained by polycondensation reaction of dicarboxylic acids and diols.

[0032] The chain extender of the present invention comprises small molecule diols and / or diamines having 2 to 15 carbon atoms, selected from one or more of ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, isopentanediol, neopentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanediol, decanediol and dodecanediol, 1,3-propanediamine, 1,4-butanediamine, p-phenylenediamine, and biphenyldiamine; preferably one or more of 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, isopentanediol, and 3-methyl-1,5-pentanediol.

[0033] The chain extender described in this invention also includes other types of chain extenders mentioned in patent CN116162220A.

[0034] Both trans,trans'-HMDI and cis,trans'-HMDI contain trans structures. In their research on TPU materials, the inventors discovered that due to conformational differences, trans structures exhibit higher symmetry and better crystallinity. TPU particles made from HMDI containing trans structures have tight molecular bonding, leading to increased tensile strength. However, when the trans structure content in TPU is too high, crystallization easily occurs during TPU particle processing, resulting in reduced light transmittance.

[0035] The inventors also discovered that, due to the asymmetry in the molecular structure of the isomer 2,4'-HMDI compared to 4,4'-HMDI in the HMDI composition, an excessive amount of 2,4'-HMDI when used to prepare TPU particles will lead to a decrease in the elasticity of the film made from the TPU particles during stretching. Therefore, the lower the 2,4'-HMDI content, the better.

[0036] Therefore, the present invention limits the content of 2,4'-HMDI isomer in the HMDI composition to <2%wt, and limits the F value of the HMDI composition to 0.23-0.64, preferably 0.26-0.59, more preferably 0.30-0.54.

[0037] Compared with the prior art, the thermoplastic polyurethane elastomer prepared from the dicyclohexylmethane diisocyanate composition provided by the present invention has extremely high tensile strength. Detailed Implementation

[0038] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0039] Example 1: Preparation of HMDI compositions of different specifications

[0040] A diphenylmethane diamine (MDA) composition was prepared by the method in Example 1 of patent CN101429139B. The MDA composition contains 4% wt of 2,4'-diphenylmethane diamine (2,4'-MDA) and 96% wt of 4,4'-diphenylmethane diamine (4,4'-MDA).

[0041] The MDA of the above specifications was used to prepare a dicyclohexylmethanediamine composition according to the methods provided in Examples 5 and 6 of CN101429139B, wherein the content of 2,4'-HMDA was 4% wt and the content of 4,4'-HMDA was 96% wt. This composition was then phosgenated according to the method provided in patent CN103319372B to obtain an HMDI composition (sample 0). It should be noted that the isomers do not change during the phosgenation reaction of HMDA to HMDI; the change in isomer content is mainly due to the removal of some isomers entrained by impurities during the separation process.

[0042] Using the gas chromatography method provided by industry standard HG / T 6064-2022, the composition of sample 0 was analyzed to include 3.6% wt of 2,4'-HMDI and 96.4% wt of 4,4'-HMDI, of which trans,trans'-HMDI accounted for 18.5% wt, cis,cis'-HMDI accounted for 32.4% wt, and cis,trans'-HMDI accounted for 45.5% wt.

[0043] The obtained HMDI composition (sample 0) was subjected to further distillation with 25 distillation trays, a pressure of 0.2 kPa, and a temperature between 170 and 195 °C. The first 10% wt fraction collected in the order of distillation was collected as sample 1, the 12-20% wt fraction collected in the order of distillation was collected as sample 2, and the 60-75% wt fraction collected in the order of distillation was collected as sample 3.

[0044] The gas chromatographic analysis of samples 1 to 3 was performed according to industry standard HG / T 6064-2022.

[0045] Sample 1 consists of 35.2% wt of 2,4'-HMDI and 64.8% wt of 4,4'-HMDI, of which 0.1% wt is trans,trans'-HMDI, 58.2% wt is cis,cis'-HMDI, and 6.5% wt is cis,trans'-HMDI.

[0046] Sample 2 consists of 0.8% wt of 2,4'-HMDI and 99.2% wt of 4,4'-HMDI, of which trans,trans'-HMDI is 4.2% wt, cis,cis'-HMDI is 68.4% wt, and cis,trans'-HMDI is 26.6% wt.

[0047] Sample 3 consists of 0.1% wt of 2,4'-HMDI and 99.9% wt of 4,4'-HMDI, of which trans,trans'-HMDI is 47.8% wt, cis,cis'-HMDI is 8.7% wt, and cis,trans'-HMDI is 43.4% wt.

[0048] Samples 0, 1, 2, and 3 were blended in a certain proportion to obtain HMDI compositions with different isomer contents, which were named as blended samples 1 to 13. The specific blending proportions and the content of each isomer in the blended HMDI compositions are shown in the table below:

[0049] Table 1. Blending ratio and isomer content of HMDI composition samples

[0050]

[0051]

[0052] Example 2: Evaluation of HMDI composition for TPU particle preparation

[0053] The TPU particle preparation method, according to the scheme provided in patent CN116162220A, includes the following components:

[0054] 1) HMDI: 34wt%;

[0055] 2) Polytetramethylene ether polyol (BASF, number average molecular weight 2000): 45wt%;

[0056] 3) Chain extender 1 + chain extender 4: 21.9 wt%;

[0057] 4) Catalyst (stannous octoate): 0.1 wt%;

[0058] Among them, chain extender 1 and chain extender 4 are consistent with those provided by CN116162220A, and their molar ratio is 5:1.

[0059] The above components (HMDI, polytetramethylene ether polyol, chain extender, and catalyst) were added to a twin-screw extruder via a feeding and injection system. After reactive extrusion, underwater pelletizing, and drying, thermoplastic polyurethane elastomer granules were obtained. These granules were then processed into parts and tested according to relevant testing methods. The extruder temperature was set to [temperature value missing]. The screw speed is 200 rpm.

[0060] In the examples, 10 batches of HMDI compositions, including blended samples 2-11, were tested to obtain different batches of TPU particles.

[0061] Comparative Example 1

[0062] The same method as in Example 2 was used, but the HMDI compositions used were tested in seven batches: samples 0, 1, 2, 3 and blended samples 1, 12, 13, to obtain different batches of TPU particles.

[0063] The products prepared in the above embodiments and comparative examples were subjected to performance tests. The light transmittance and haze test samples were all 0.15 mm cast films. The specific test methods were carried out according to the methods provided in GB / T2410-2008. The resilience and elongation at break tests were conducted according to ASTM D412 standard, and the 0.15 mm films were tested.

[0064] The F-value content of 10 batches of samples in Example 2 and 7 HMDI compositions in Comparative Example 1, as well as the mass of TPU particles obtained in different batches, are shown in the table below:

[0065] Table 2

[0066]

[0067] The results in the table above show that the 10 batches of HMDI compositions tested in Example 2 have significant advantages over the comparative examples in the TPU particle application test.

[0068] The present invention has been illustrated with the above embodiments to explain the detailed method of the present invention. However, the present invention is not limited to the detailed method described above, that is, it does not mean that the present invention must rely on the detailed method described above to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A dicyclohexylmethane dicyanate (HMDI) composition, characterized in that, The content of the isomer 2,4'-dicyclohexylmethane diisocyanate 2,4'-HMDI in the dicyclohexylmethane diisocyanate HMDI composition is >0 and <2%wt, and the F value of the HMDI composition is in the range of 0.23-0.64; The formula for calculating the F value is: F = (0.5 × cis, trans'-HMDI content % wt + trans, trans'-HMDI content % wt) ÷ 100% wt.

2. The dicyclohexylmethane diisocyanate (HMDI) composition according to claim 1, characterized in that, The F value is 0.26-0.

59.

3. The dicyclohexylmethane diisocyanate (HMDI) composition according to claim 1, characterized in that, The F value is 0.30-0.

54.

4. The dicyclohexylmethane diisocyanate (HMDI) composition according to claim 1, characterized in that, The structure of cis,trans-HMDI in the dicyclohexylmethane diisocyanate (HMDI) composition is as follows: ; The trans,trans'-HMDI structure in the dicyclohexylmethane diisocyanate (HMDI) composition is as follows: .

5. A thermoplastic polyurethane elastomer, comprising the following components: (1) 25-45 wt% of the dicyclohexylmethane diisocyanate (HMDI) composition according to any one of claims 1-4; (2) At least one polyol, 40-65 wt%; (3) At least one chain extender, 4-25 wt%; (4) Catalyst 0.10-0.2wt%.

6. The thermoplastic polyurethane elastomer according to claim 5, characterized in that, The polyol is selected from one or more of conventional polyester polyols, polylactone polyols, polyether polyols, or polycarbonate polyols.

7. The thermoplastic polyurethane elastomer according to claim 6, characterized in that, The polyol is selected from one or more of polycaprolactone diol, polycarbonate diol, and polytetramethylene ether diol.

8. The thermoplastic polyurethane elastomer according to claim 5, characterized in that, The number-average molecular weight of the polyol is 700-4000 g / mol.

9. The thermoplastic polyurethane elastomer according to claim 5, characterized in that, The number-average molecular weight of the polyol is 1000-3000 g / mol.

10. The thermoplastic polyurethane elastomer according to claim 5, characterized in that, The chain extender includes diols and / or diamines having 2 to 15 carbon atoms.

11. The thermoplastic polyurethane elastomer according to claim 10, characterized in that, The chain extender includes one or more of the following: ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 1,5-pentanediol, isopentanediol, neopentanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanediol, decanediol and dodecanediol, 1,3-propanediamine, 1,4-butanediamine, p-phenylenediamine, and biphenyldiamine.

Images