Dicyclohexylmethane diisocyanate composition and thermoplastic polyurethane elastomer

Abstract

The invention discloses a dicyclohexylmethane diisocyanate composition and a thermoplastic polyurethane elastomer. The content of an isomer 2, 4 '-dicyclohexylmethane diisocyanate (2, 4'-HMDI) in the dicyclohexylmethane dicyanic acid ester composition (HMDI) is less than 2% wt, and the F value range of the HMDI composition is 0.23-0.64. The thermoplastic polyurethane elastomer prepared from the dicyclohexylmethane diisocyanate composition provided by the invention has extremely high light transmittance and extremely high tensile strength.

Description

Technical Field

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

[0002] Dicyclohexylmethane diisocyanate (HMDI for short) is an aliphatic isocyanate. Since there is no benzene ring in its structure, it has 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, UV resins, etc.

[0003] Especially in the field of TPU applications, with the gradual development of TPU substrates for car cover films in recent years, the performance requirements for TPU particles are getting higher and higher. For example, patent CN116162220A provides a highly transparent, highly resilient, flame-retardant thermoplastic polyurethane elastomer and its preparation method and application, which has high transparency, high resilience and flame retardant properties, and is particularly suitable for TPU substrates for car cover films.

[0004] The industry standard HG / T 6064-2022 discloses that HMDI contains two isomers: 2,4'-HMDI and 4,4'-HMDI. At the same time, 4,4'-HMDI also includes 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 field of 3D printing. However, the use effect of this specification product in the field of TPU car cover film is not outstanding.

[0006] However, in the field of TPU applications, with the gradual development of TPU substrates for car cover films in recent years, the performance requirements for TPU particles are becoming increasingly higher. For example, patent CN116162220A provides a highly transparent, highly resilient, flame-retardant thermoplastic polyurethane elastomer and its preparation method and application, which has high transparency, high resilience and flame retardant properties, and is particularly suitable for TPU substrates for car cover films.

[0007] Patent CN111909504A discloses a polyurethane flame-retardant film for invisible car cover, its preparation method and use. 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 a thermoplastic polyurethane elastomer with extremely high light transmittance and extremely strong tensile strength. Summary of the invention

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

[0010] To achieve the above object, the present invention adopts the following technical solutions:

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

[0012] The content of cyclohexylmethane diisocyanate (2,4'-HMDI) is less than 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 calculation formula of the F value of the dicyclohexylmethane diisocyanate composition of the present invention is:

[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, the specific structure of cis- and trans-HMDI in the dicyclohexylmethane diisocyanate composition is:

[0016] The specific structure of trans-HMDI in the dicyclohexylmethane diisocyanate composition of the present invention is:

[0017]

[0018] There is no specific requirement for the preparation method of the HMDI composition of the present invention, and the HMDI composition of the composition can be obtained by any feasible method.

[0019] Method 1: The HMDI composition of the present invention is prepared by regulating 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 the present invention can be achieved by regulating 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 regulating 2,4'-HMDA in HMDA disclosed in patent CN101429139A, and the method for regulating t,t'-HMDA is also mentioned in patent CN103265438A.

[0020] Method 2: Existing dicyclohexylmethane dicyanate products with different isomer compositions are used to prepare the dicyclohexylmethane dicyanate composition of the present invention through a separation process. In the subsequent separation process of preparing the HMDI product from HMDA, the content of different isomers in the HMDI composition is adjusted through different separation processes such as crystallization and distillation.

[0021] Method 3: preparing the dicyclohexylmethane dicyanate composition of the present invention by mixing different isomers, for example, by adding corresponding isomers to a conventional HMDI composition.

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

[0023] The content of relevant isomers in the dicyclohexylmethane diisocyanate composition of the present invention is tested by the method provided in HG / T6064-2022.

[0024] The HMDI composition of the present invention can be used in the field of thermoplastic polyurethane elastomer TPU, and the prepared thermoplastic polyurethane elastomer has extremely high light transmittance and extremely low haze.

[0025] A TPU comprising the following components:

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

[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 polyol of the present invention is 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 polyol is 700-4000 g / mol, preferably 1000-3000 g / mol. The specific preparation method can be prepared by referring to the method mentioned in patent CN116162220A.

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

[0032] The chain extender of the present invention comprises a small molecule diol and / or a diamine having 2 to 15 carbon atoms, and is selected from one or more of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, isoprene glycol, neopentyl glycol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanedimethanol, decanediol and dodecanediol, 1,3-propylenediamine, 1,4-butanediamine, p-phenylenediamine, and biphenylenediamine; preferably one or more of 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, isoprene glycol, and 3-methyl-1,5-pentanediol.

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

[0034] Both trans, trans'-HMDI and cis, trans'-HMDI contain trans structures. The inventors found in their research on TPU materials that due to differences in molecular conformation, the trans structure has a higher symmetry and better crystallization performance. TPU particles made of HMDI containing a trans structure have tightly bound molecules, which in turn increases their tensile strength. However, when the content of the trans structure in TPU is too high, crystallization is likely to occur during the processing of the TPU particles, resulting in a decrease in the light transmittance of the TPU particles.

[0035] At the same time, the inventors also found that due to the asymmetry of the molecular structure of the isomer 2,4'-HMDI in the HMDI composition compared to 4,4'-HMDI, excessive 2,4'-HMDI content when used to prepare TPU particles will lead to a decrease in the resilience of the film made of TPU particles when stretched, so 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 less than 2%wt, and limits the F value of the HMDI composition to 0.23-0.64, preferably 0.26-0.59, and 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 DESCRIPTION

[0038] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

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

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

[0041] The MDA of the above specifications was used according to the method provided in Example 5 and Example 6 of CN101429139B to prepare a dicyclohexylmethane diamine composition, wherein the 2,4'-HMDA content was 4%wt and the 4,4'-HMDA content was 96%wt, and then phosgenated according to the method provided in patent CN103319372B to obtain a HMDI composition (sample 0). It should be particularly noted that the isomers do not change during the phosgenation reaction of HMDA to prepare HMDI, and the change in the amount of isomers is mainly due to the removal of impurities during the separation process. The entrainment of part of the isomers.

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

[0043] The obtained HMDI composition (sample 0) was distilled again with 25 distillation plates, a pressure of 0.2 KPa, and a temperature between 170 and 195° C. The first 10% wt fraction in the extraction sequence was collected as sample 1, the 12-20% wt fraction in the extraction sequence was collected as sample 2, and the 60-75% wt fraction in the extraction sequence was collected as sample 3.

[0044] The gas chromatography analysis samples 1 to 3 provided by the industry standard HG / T 6064-2022 are composed of:

[0045] The composition of sample 1 includes 35.2% wt of 2,4'-HMDI and 64.8% wt of 4,4'-HMDI, of which the content of trans, trans'-HMDI is 0.1% wt, the content of cis, cis'-HMDI is 58.2% wt, and the content of cis, trans'-HMDI is 6.5% wt.

[0046] Sample 2, the composition includes 2,4'-HMDI 0.8%wt, 4,4'-HMDI 99.2%wt, 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, the composition includes 2,4'-HMDI 0.1%wt, 4,4'-HMDI 99.9%wt, 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] The obtained samples 0, 1, 2 and 3 were blended in a certain ratio to obtain HMDI compositions with different isomer contents, which were named as blended samples 1 to 13. The specific blending ratios and the contents of each isomer in the blended HMDI compositions are shown in the following table:

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

[0050]

[0051]

[0052] Example 2 Preparation and Evaluation of HMDI Composition TPU Particles

[0053] The TPU particle preparation method is based on the solution provided by patent CN116162220A, and includes the following components:

[0054] 1) HMDI: 34 wt%;

[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): 0.1wt%;

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

[0059] The above components (HMDI, polytetramethylene ether polyol, chain extender, catalyst) are added to the twin-screw extruder through the feeding and perfusion system. After reaction extrusion, underwater pelletizing and drying, thermoplastic polyurethane elastomer particles are obtained. The particles are processed into parts and tested according to relevant test methods. The extruder temperature is set to The screw speed is 200 rpm.

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

[0061] Comparative Example 1

[0062] The same method as in Example 2 was adopted, but the HMDI compositions used were samples 0, 1, 2, 3 and blended samples 1, 12, 13, a total of 7 batches were tested separately to obtain different batches of TPU particles.

[0063] The products obtained in the above embodiments and comparative examples were subjected to performance tests, wherein the transmittance and haze test samples were all 0.15 mm cast films, and the specific testing method was carried out in accordance with the method provided in GB / T2410-2008, and the rebound performance and elongation at break tests were carried out in accordance with ASTM D412 standard, and 0.15 mm films were tested.

[0064] The F value contents of the 10 batches of samples in Example 2 and the 7 HMDI compositions in Comparative Example 1 and the quality of the TPU particles obtained in different batches are shown in the following table:

[0065] Table 2

[0066]

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

[0068] The present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various 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 composition, characterized in that: The content of isomer 2,4'-dicyclohexylmethane diisocyanate 2,4'-HMDI in the dicyclohexylmethane dicyanate composition is less than 2%wt, and the F value of the HMDI composition is in the range of 0.23-0.

64.

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

59.

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

54.

4. The dicyclohexylmethane diisocyanate composition according to claim 1, characterized in that: The calculation formula of the F value is: F = (0.5 × cis, trans'-HMDI content %wt + trans, trans'-HMDI content %wt) ÷ 100%wt.

5. The dicyclohexylmethane diisocyanate composition according to any one of claims 1 to 4, characterized in that The structure of cis- and trans-HMDI in the dicyclohexylmethane diisocyanate composition is: The structure of trans-HMDI in the dicyclohexylmethane diisocyanate composition is:

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

7. The thermoplastic polyurethane elastomer according to claim 6, characterized in that: The polyol is 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 glycol.

8. The thermoplastic polyurethane elastomer according to claim 6, characterized in that The number average molecular weight of the polyol is 700-4000 g / mol, preferably 1000-3000 g / mol.

9. The thermoplastic polyurethane elastomer according to claim 6, characterized in that: The chain extender includes diols and / or diamines having 2 to 15 carbon atoms.

10. The thermoplastic polyurethane elastomer according to claim 9, characterized in that: The chain extender includes one or more of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,5-pentanediol, isoprene glycol, neopentyl glycol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, diethylene glycol, 1,4-cyclohexanedimethanol, decanediol and dodecanediol, 1,3-propylenediamine, 1,4-butanediamine, p-phenylenediamine, and diphenylenediamine.

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