An ink migration resistant TPU by mass polymerization and a method for preparing the same

Abstract

The application belongs to the technical field of polyurethane, and particularly relates to a bulk polymerization ink migration resistant TPU and a preparation method thereof. The raw materials of the bulk polymerization ink migration resistant TPU of the application include the following components in parts by weight: 30-40 parts of polymeric polyol, 10-15 parts of hydroxyl-terminated polybutadiene resin, 5-8 parts of hydroxyl-terminated fluororesin, 30-35 parts of diisocyanate, 7-10 parts of chain extender, 2-4 parts of titanium white, and an additive. The bulk polymerization ink migration resistant TPU of the application has good affinity with ink, which helps to significantly improve the adhesion of the TPU and the ink and inhibit the migration of the ink.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane technology, specifically relating to a bulk polymerized ink migration-resistant TPU and its preparation method. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU) is generally a block linear polymer material formed by the reaction of diisocyanate, macromolecular polyol, and chain extender. From the perspective of molecular structure, it is composed of alternating rigid segments (hard segments) and flexible segments (soft segments). Among them, the soft segments provide the elastomer with properties such as toughness, elasticity, and low temperature resistance, while the hard segments provide the elastomer with properties such as rigidity, strength, and heat resistance.

[0003] However, thermoplastic polyurethane elastomer has a two-phase separation structure at the microscopic level, with high polarity and poor affinity with ink. When heat transfer or printing ink on TPU products, the ink will quickly migrate, resulting in unclear and mottled patterns on the product surface.

[0004] Developing a thermoplastic polyurethane elastomer with high affinity for ink and that inhibits ink migration is a technical problem that urgently needs to be solved in this field.

[0005] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0006] The purpose of this invention is to provide a bulk polymerized TPU resistant to ink migration and its preparation method, so as to help solve or improve the problems in the prior art where TPU has poor affinity with ink and ink is prone to migration when heat transfer or printing ink on TPU products.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a bulk polymerized ink migration resistant TPU, wherein the raw materials of the bulk polymerized ink migration resistant TPU include the following components in parts by weight: 30-40 parts of polymeric polyol, 10-15 parts of hydroxyl-terminated polybutadiene resin, 5-8 parts of hydroxyl-terminated fluororesin, 30-35 parts of diisocyanate, 7-10 parts of chain extender, 2-4 parts of titanium dioxide, and additives.

[0008] Preferably, the polymeric polyol is a polyester polyol and / or a polyether polyol; the polyester polyol includes at least one of polyethylene adipate diol, polybutylene adipate diol, and polyethylene adipate butylene adipate diol; the polyether polyol includes polytetrahydrofuran diol; and the number average molecular weight of the polymeric polyol is 1500-3500.

[0009] Preferably, the molecular weight of the hydroxyl-terminated polybutadiene resin is 1000-3000, and the structural formula of the hydroxyl-terminated polybutadiene resin is shown below:

[0010]

[0011] Preferably, the molecular weight of the hydroxyl-terminated fluoropolymer is 1000-3000, and the structural formula of the hydroxyl-terminated fluoropolymer is shown below:

[0012]

[0013] Preferably, the diisocyanate includes at least one of 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; the chain extender includes a C2-C10 straight-chain alkane diol.

[0014] Preferably, the chain extender includes at least one selected from 1,2-ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0015] Preferably, the adjuvant is an antioxidant and / or a catalyst; the antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N-bis-[3-(3,5,-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine and octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate; the catalyst includes stannous octoate and / or dibutyltin dilaurate.

[0016] Preferably, the catalyst content in the raw materials for preparing the bulk polymerized ink migration resistant TPU is 30-80 ppm; the mass ratio of the antioxidant to the polymer polyol is (1-2):(30-40).

[0017] This invention also provides a method for preparing the bulk-polymerized ink migration-resistant TPU as described above, which adopts the following technical solution: The method for preparing the bulk-polymerized ink migration-resistant TPU includes the following steps: mixing polymeric polyol, hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluororesin, titanium dioxide and additives evenly and placing them in container A; placing the diisocyanate in container B; placing the chain extender in container C; injecting the components in containers A, B and C into a twin-screw extruder through a casting machine; reacting in the twin-screw extruder to obtain the bulk-polymerized ink migration-resistant TPU; the screw speed of the twin-screw extruder is 180-230 rpm, and the operating temperature range of the twin-screw extruder is 180-210℃.

[0018] Preferably, the temperature of container A is maintained at 95-105℃, the temperature of container B is maintained at 45-55℃, and the temperature of container C is maintained at 45-50℃; after the reaction in the twin-screw extruder is completed, the process further includes underwater pelletizing and drying; the drying temperature is 80-100℃, and the drying time is 6-9 hours.

[0019] Beneficial effects:

[0020] The raw materials for preparing the bulk polymerized ink migration-resistant TPU provided by this invention include polymeric polyol, hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluoropolymer, diisocyanate, chain extender, titanium dioxide, and other additives. By introducing hydroxyl-terminated polybutadiene resin and hydroxyl-terminated fluoropolymer to modify the TPU, polybutadiene and fluorine elements can be successfully introduced into the polyurethane molecular chain, reducing the polarity of the TPU and enabling the surface dyne value of the TPU to reach between 40 and 42. This improves the affinity between the TPU and ink, significantly enhances the adhesion between the TPU and ink, and effectively inhibits ink migration. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0022] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0023] This invention addresses the problems of poor affinity between TPU and ink during current TPU applications, and the tendency for ink to migrate during heat transfer or printing on TPU. It provides a bulk polymerized TPU that is resistant to ink migration.

[0024] The raw materials for the bulk polymerized ink migration-resistant TPU of this invention include the following components in parts by weight: 30-40 parts of polymeric polyol (e.g., 30, 32, 34, 36, or 40 parts), 10-15 parts of hydroxyl-terminated polybutadiene resin (e.g., 10, 11, 12, 13, 14, or 15 parts), 5-8 parts of hydroxyl-terminated fluoropolymer (e.g., 5, 5.5, 6, 6.5, 7, 7.5, or 8 parts), 30-35 parts of diisocyanate (e.g., 30, 31, 32, 33, 34, or 35 parts), 7-10 parts of chain extender (e.g., 7, 7.5, 8, 8.5, 9, 9.5, or 10 parts), 2-4 parts of titanium dioxide (e.g., 2, 2.5, 3, 3.5, or 4 parts), and additives. In this invention, titanium dioxide plays the following main roles: (1) improving whiteness; (2) improving the heat resistance, light resistance and weather resistance of the product.

[0025] In this invention, TPU is modified by introducing hydroxyl-terminated polybutadiene resin and hydroxyl-terminated fluoropolymer resin. This successfully introduces carbon-carbon double bonds and fluorine elements into the polyurethane molecular chain, reducing the polarity of the TPU and achieving a surface dyne value between 40 and 42. This improves the affinity between TPU and ink, significantly enhancing their adhesion and effectively inhibiting ink migration. Therefore, this product can be widely used in TPU applications where ink migration resistance is critical.

[0026] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the polymer polyol is a polyester polyol and / or a polyether polyol; the polyester polyol includes at least one of polyethylene adipate diol, polybutylene adipate diol, and polyethylene adipate butylene adipate diol; the polyether polyol includes polytetrahydrofuran diol.

[0027] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the number average molecular weight of the polymer polyol is 1500-3500 (e.g., 1500, 1700, 1900, 2100, 2300, 2500, 2700, 2900, 3100, 3300, or 3500). When the molecular weight of the polymer polyol is greater than 3500, the overall system viscosity is too high, which is detrimental to the dispersion of additives such as catalysts and titanium dioxide during synthesis, thus affecting the mechanical properties of the TPU. When the molecular weight of the polymer is less than 1500, the crystallinity of the synthesized TPU is poor, and the TPU molding time is long, which is not conducive to subsequent continuous industrial production.

[0028] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the molecular weight of the hydroxyl-terminated polybutadiene resin is 1000-3000, and the structural formula of the hydroxyl-terminated polybutadiene resin is shown below:

[0029]

[0030] In particular, because hydroxyl-terminated polybutadiene resin has an asymmetric structure, when the molecular weight of hydroxyl-terminated polybutadiene resin is less than 1000, the entanglement of polymer macromolecular chains will decrease, resulting in poor crystallinity of the synthesized TPU and a longer TPU molding time. When the molecular weight of hydroxyl-terminated polybutadiene fluoropolymer is greater than 3000, the molecular chain entanglement is severe, which is not conducive to the mixing of hydroxyl-terminated polybutadiene fluoropolymer with polyol, and compatibility problems will occur, thus affecting the physical properties.

[0031] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the molecular weight of the hydroxyl-terminated fluoropolymer is 1000-3000, and the structural formula of the hydroxyl-terminated fluoropolymer is shown below:

[0032]

[0033] When the molecular weight of the hydroxyl-terminated fluoropolymer is less than 1000, the crystallinity deteriorates during polymerization, which is not conducive to the overall polymerization reaction of TPU. When the molecular weight of the hydroxyl-terminated fluoropolymer is greater than 3000, the molecular chain entanglement is severe, which is not conducive to the mixing of the hydroxyl-terminated fluoropolymer with the polyol, and compatibility problems will occur, leading to stratification.

[0034] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the diisocyanate includes at least one of 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and hexamethylene diisocyanate; the chain extender includes at least one of C2-C10 straight-chain alkane diols.

[0035] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the chain extender includes at least one selected from 1,2-ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

[0036] In a preferred embodiment of the bulk polymerized ink migration-resistant TPU of the present invention, the additives are antioxidants and / or catalysts; the antioxidants include at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), N,N-bis-[3-(3,5,-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine (antioxidant 1098) and octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate (antioxidant 1076); the catalysts include stannous octoate and / or dibutyltin dilaurate.

[0037] In a preferred embodiment of the bulk-polymerized ink migration-resistant TPU of the present invention, the mass ratio of antioxidant to polymeric polyol in the raw materials for preparing the bulk-polymerized ink migration-resistant TPU is (1-2):(30-40) (for example, the mass ratio of antioxidant to polymeric polyol is 1:30, 2:30, 1:40, 2:40, 1:35 or 2:35, etc.), and the content of catalyst is 30-80 ppm (for example, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm or 80 ppm).

[0038] This invention also proposes a method for preparing a bulk-polymerized ink migration-resistant TPU. The method for preparing the bulk-polymerized ink migration-resistant TPU of this invention includes the following steps: a polymeric polyol, hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluororesin, titanium dioxide, and additives are mixed evenly and placed in container A; diisocyanate is placed in container B; chain extender is placed in container C; the components in containers A, B, and C are injected into a twin-screw extruder through a casting machine; and the reaction takes place in the twin-screw extruder to obtain the bulk-polymerized ink migration-resistant TPU; the screw speed of the twin-screw extruder is 180-230 rpm (e.g., 180 rpm, 190 rpm, 200 rpm, 210 rpm, 220 rpm, or 230 rpm), and the operating temperature range of the twin-screw extruder is 180-210℃.

[0039] In a preferred embodiment of the method for preparing the bulk polymerized ink migration-resistant TPU of the present invention, the temperature of container A is maintained at 95-105°C (e.g., 95°C, 97°C, 99°C, 102°C, or 105°C), the temperature of container B is maintained at 45-55°C (e.g., 45°C, 47°C, 49°C, 51°C, 53°C, or 55°C), and the temperature of container C is maintained at 45-50°C (e.g., 45°C, 46°C, 47°C, 48°C, 49°C, or 50°C). After the reaction in the twin-screw extruder is completed, the method further includes underwater pelletizing and drying steps. The drying temperature is 80-100°C (e.g., 80°C, 84°C, 89°C, 93°C, 97°C, or 100°C), and the drying time is 6-9 hours (e.g., 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, or 9 hours).

[0040] The following detailed description of the bulk polymerized ink migration-resistant TPU and its preparation method of the present invention is provided through specific embodiments.

[0041] In the following embodiment:

[0042] The polymer polyols selected are polytetrahydrofuran glycol (PTMG2000, Mitsubishi Chemical, Japan) with a molecular weight of 2000; hydroxyl-terminated polybutadiene resin with a molecular weight of 2000 (Krasol LBH-2000, Cray Valley); and hydroxyl-terminated fluoropolymer resin with a molecular weight of 2000 (Tech-2203, Chongqing Heccom New Material Technology Co., Ltd.).

[0043] Example 1

[0044] The raw materials of the bulk polymerized ink migration resistant TPU of this embodiment include the following components in parts by weight: 30 parts polymer polyol, 10 parts hydroxyl-terminated polybutadiene resin, 5 parts hydroxyl-terminated fluororesin, 30 parts diisocyanate (MDI), 7 parts chain extender (1,4-butanediol), 2 parts titanium dioxide, 1 part antioxidant (antioxidant 1010), and catalyst (stannous octoate).

[0045] The method for preparing bulk polymerized ink migration-resistant TPU in this embodiment includes the following steps:

[0046] (1) Polytetrahydrofuran diol (molecular weight 2000, Mitsubishi Chemical PTMG2000), hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluoropolymer, titanium dioxide, antioxidant 1010, and stannous octoate (the amount of stannous octoate is 65 ppm of the total weight of each raw material) are thoroughly mixed and added to tank A. The temperature of tank A is maintained at 95°C and nitrogen gas is purged throughout the process.

[0047] Among them, hydroxyl-terminated polybutadiene resin, molecular weight 2000 (Krasol LBH-2000, Cray Valley Corporation); hydroxyl-terminated fluoropolymer resin, molecular weight 2000 (Chongqing Heccom New Material Technology Co., Ltd., Tech-2203);

[0048] (2) Place the MDI in container B, maintain the temperature of container B at 55°C, and keep container B under nitrogen protection throughout the process.

[0049] (3) Place 1,4-butanediol in container C, maintain the temperature of container C at 50°C, and keep container C under nitrogen protection throughout the process.

[0050] (4) All components in the above-mentioned tanks A, B and C are injected into a twin-screw extruder through a casting machine for reaction. The screw speed of the twin-screw extruder is set at 175 rpm, and the temperature range is set between 180 and 210°C (specifically, 180°C, 185°C, 185°C, 185°C, 190°C, 190°C, 195°C, 195°C, 195°C, 200°C, 200°C, 200°C, 205°C, 210°C). After underwater pelletizing, the product is dried in an 80°C drying oven for 6 hours to obtain the bulk polymerized ink migration resistant TPU of this embodiment.

[0051] Example 2

[0052] The raw materials of the bulk polymerized ink migration resistant TPU of this embodiment include the following components in parts by weight: 40 parts of polymeric polyol, 15 parts of hydroxyl-terminated polybutadiene resin, 8 parts of hydroxyl-terminated fluoropolymer, 35 parts of diisocyanate (MDI), 10 parts of chain extender (1,4-butanediol), 4 parts of titanium dioxide, 2 parts of antioxidant (antioxidant 1010) and catalyst (stannous octoate).

[0053] The method for preparing bulk polymerized ink migration-resistant TPU in this embodiment includes the following steps:

[0054] (1) Polytetrahydrofuran diol (molecular weight 2000, Mitsubishi Chemical PTMG2000), hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluoropolymer, titanium dioxide, antioxidant 1010, and stannous octoate (the amount of stannous octoate is 65 ppm of the total weight of each raw material) are thoroughly mixed and added to tank A. The temperature of tank A is maintained at 95°C and nitrogen gas is purged throughout the process.

[0055] Among them, hydroxyl-terminated polybutadiene resin with a molecular weight of 2000 (Krasol LBH-2000, Cray Valley Corporation); hydroxyl-terminated fluoropolymer resin with a molecular weight of 2000 (Chongqing Heccom New Material Technology Co., Ltd., Tech-2203);

[0056] (2) Place the MDI in container B, maintain the temperature of container B at 55°C, and keep container B under nitrogen protection throughout the process.

[0057] (3) Place 1,4-butanediol in container C, maintain the temperature of container C at 50°C, and keep container C under nitrogen protection throughout the process.

[0058] (4) All components in the above-mentioned tanks A, B and C are injected into a twin-screw extruder through a casting machine for reaction. The screw speed of the twin-screw extruder is set at 175 rpm, and the temperature range is set between 180 and 210°C (specifically, 180°C, 185°C, 185°C, 185°C, 190°C, 190°C, 195°C, 195°C, 195°C, 200°C, 200°C, 200°C, 205°C, 210°C). After underwater pelletizing, the product is dried in an 80°C drying kettle for 6 hours to obtain the bulk polymerized ink migration resistant TPU of this embodiment.

[0059] Example 3

[0060] The raw materials for the bulk polymerized ink migration resistant TPU of this embodiment include the following components in parts by weight: 35 parts polymer polyol, 12.5 parts hydroxyl-terminated polybutadiene resin, 6.5 parts hydroxyl-terminated fluoropolymer, 32.5 parts diisocyanate (MDI), 8.5 parts chain extender (1,4-butanediol), 3 parts titanium dioxide, 1.5 parts antioxidant (antioxidant 1010), and catalyst (stannous octoate).

[0061] The method for preparing bulk polymerized ink migration-resistant TPU in this embodiment includes the following steps:

[0062] (1) Polytetrahydrofuran diol (molecular weight 2000, Mitsubishi Chemical PTMG2000, Japan),

[0063] Hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluoropolymer, titanium dioxide, antioxidant 1010, and stannous octoate (the amount of stannous octoate is 65 ppm of the total weight of each raw material) are thoroughly mixed and added to container A. The temperature of container A is maintained at 95°C, and container A is protected by nitrogen gas throughout the process.

[0064] Among them, hydroxyl-terminated polybutadiene resin, molecular weight 2000 (Krasol LBH-2000, Cray Valley Corporation); hydroxyl-terminated fluoropolymer resin, molecular weight 2000 (Chongqing Heccom New Material Technology Co., Ltd., Tech-2203);

[0065] (2) Place the MDI in container B, maintain the temperature of container B at 55°C, and keep container B under nitrogen protection throughout the process.

[0066] (3) Place 1,4-butanediol in container C, maintain the temperature of container C at 50°C, and keep container C under nitrogen protection throughout the process.

[0067] (4) All components in the above-mentioned tanks A, B and C are injected into a twin-screw extruder through a casting machine for reaction. The screw speed of the twin-screw extruder is set at 175 rpm, and the temperature range is set between 180 and 210°C (specifically, 180°C, 185°C, 185°C, 185°C, 190°C, 190°C, 195°C, 195°C, 195°C, 200°C, 200°C, 200°C, 205°C, 210°C). After underwater pelletizing, the product is dried in an 80°C drying oven for 6 hours to obtain the bulk polymerized ink migration resistant TPU of this embodiment.

[0068] Example 4

[0069] The bulk polymerized ink migration resistant TPU of this embodiment differs from that of Example 1 only in that polyethylene adipate diol (Shanghai Huide Technology Co., Ltd., HDPOL-4420) is used instead of polytetrahydrofuran diol. All other components, dosages, and preparation methods are the same as in Example 1.

[0070] Example 5

[0071] The bulk polymerized ink migration resistant TPU of this embodiment differs from that of Example 1 only in that dicyclohexylmethane diisocyanate (HMDI) is used instead of MDI. All other components, dosages, and preparation methods are the same as in Example 1.

[0072] Comparative Example 1

[0073] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the raw materials do not include hydroxyl-terminated polybutadiene resin, and the amount of hydroxyl-terminated polybutadiene resin is added to the mass fraction of polytetrahydrofuran diol. The other components, amounts, and preparation methods are the same as in Example 1.

[0074] Comparative Example 2

[0075] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the raw materials do not include hydroxyl-terminated fluoropolymer, and the amount of hydroxyl-terminated fluoropolymer is added to the mass fraction of polytetrahydrofuran diol. The other components, amounts, and preparation methods are the same as in Example 1.

[0076] Comparative Example 3

[0077] The polyurethane elastomer in this comparative example differs from that in Example 1 only in that the raw materials do not include hydroxyl-terminated fluoropolymer and hydroxyl-terminated polybutadiene resin, and the amounts of hydroxyl-terminated fluoropolymer and hydroxyl-terminated polybutadiene resin are added to the mass fraction of polytetrahydrofuran diol. All other components, amounts, and preparation methods are the same as in Example 1.

[0078] Comparative Example 4

[0079] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the amount of polytetrahydrofuran diol in the raw materials is 35 parts, and the amount of hydroxyl-terminated polybutadiene resin added is 5 parts by weight. The other components, amounts and preparation methods are the same as in Example 1.

[0080] Comparative Example 5

[0081] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the amount of polytetrahydrofuran diol in the raw materials is 10 parts, and the amount of hydroxyl-terminated polybutadiene resin added is 20 parts by weight. The other components, amounts, and preparation methods are the same as in Example 1.

[0082] Comparative Example 6

[0083] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the amount of polytetrahydrofuran diol in the raw materials is 33 parts, and the amount of hydroxyl-terminated fluoropolymer added is 2 parts by weight. The other components, amounts, and preparation methods are the same as in Example 1.

[0084] Comparative Example 7

[0085] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the amount of polytetrahydrofuran diol in the raw materials is 23 parts, the amount of hydroxyl-terminated fluoropolymer added is 12 parts by weight, and the other components, amounts and preparation methods are the same as in Example 1.

[0086] Comparative Example 8

[0087] The only difference between the polyurethane elastomer in this comparative example and that in Example 1 is that the molecular weight of the hydroxyl-terminated polybutadiene resin in the raw materials is 800. The other components, amounts, and preparation methods are the same as in Example 1.

[0088] Comparative Example 9

[0089] The only difference between the polyurethane elastomer in this comparative example and that in Example 1 is that the molecular weight of the hydroxyl-terminated polybutadiene resin in the raw materials is 3500. The other components, amounts, and preparation methods are the same as in Example 1.

[0090] Comparative Example 10

[0091] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the molecular weight of the hydroxyl-terminated fluoropolymer in the raw materials is 800. The other components, amounts, and preparation methods are the same as in Example 1.

[0092] Comparative Example 11

[0093] The only difference between the polyurethane elastomer in this comparative example and that in Example 1 is that the molecular weight of the hydroxyl-terminated fluoropolymer in the raw materials is 3500. The other components, amounts, and preparation methods are the same as in Example 1.

[0094] Comparative Example 12

[0095] The only difference between the polyurethane elastomer in this comparative example and Example 1 is that the molecular weight of polytetrahydrofuran diol in the raw materials is 1000. The other components, amounts, and preparation methods are the same as in Example 1.

[0096] Experimental Example

[0097] The performance of the products obtained in the examples and comparative examples was tested respectively:

[0098] (1) Hardness: Hardness test was conducted according to the test standard provided in GB / T531-2009;

[0099] (2) Mechanical properties: Tested according to the test standards provided in GB / T528-2009;

[0100] (3) Dyne value: Tested with a dyne pen after TPU is injection molded into sheets;

[0101] (4) Evaluation of ink migration: TPU was injection molded into a sheet with dimensions of 110mm × 130mm × 2.2mm. Then, a 3mm diameter circle was drawn on the sheet using an oil-based pen (Hero Double-ended Oil-based Pen 880). After 24 hours, the sheet with the circled area was boiled in water at 100℃ for 12 hours. Then, it was taken out and the migration of the oil-based pen was observed. According to the migration, it was divided into three levels: Level A: No migration, the oil-based pen color is bright; Level B: The oil-based pen becomes thicker, and there is slight migration; Level C: The oil-based pen spreads out, and there is complete migration.

[0102] The bulk polymerized ink migration-resistant TPUs prepared in Examples 1-5 and the polyurethane elastomers prepared in Comparative Examples 1-12 were tested according to the above test methods. The test results are shown in Table 1.

[0103] Table 1

[0104]

[0105] According to the data in Table 1:

[0106] The bulk polymerized ink migration resistant TPU provided by this invention has high hardness, high dyne value and good migration resistance. Specifically, in Examples 1 to 5, when the amounts of different polymer polyols and diisocyanates, as well as hydroxyl-terminated fluoropolymers and hydroxyl-terminated polybutadiene resins, fluctuate within the range of this invention, the prepared bulk polymerized ink migration resistant TPUs can all achieve a hardness of 94 to 96A, a dyne value of around 41 to 42, and a migration resistance of A grade.

[0107] Specifically, comparing Example 1 and Comparative Examples 1-2, it can be found that when the raw materials include only one of hydroxyl-terminated polybutadiene resin or hydroxyl-terminated fluororesin, the dyne value of the resulting polyurethane elastomer is slightly reduced, and the migration reaches grade B. This is because hydroxyl-terminated polybutadiene resin contains unsaturated bonds, and fluorine in hydroxyl-terminated fluororesin has a high electronegativity. The two are combined on the same molecular chain, which has a significant synergistic effect. On the one hand, it significantly reduces the polarity of TPU, and on the other hand, it can enhance the locking force on ink.

[0108] Further comparison of Comparative Example 1 and Comparative Example 3 reveals that without the addition of hydroxyl-terminated polybutadiene resin or hydroxyl-terminated fluoropolymer, the TPU's dyne value is only 32, and the ink migrates completely, resulting in a grade of only C. Therefore, this further verifies the correctness of the above conclusions.

[0109] Comparing Example 1 and Comparative Examples 4-5, it can be found that changing the amount of hydroxyl-terminated polybutadiene resin added to the raw materials results in a slight decrease in the dyne value of the polyurethane elastomer when the amount added is small. Although the migration reaches grade A when the amount added is large, the impact on the physical properties is significant, with the hardness decreasing to 91A and the tensile strength decreasing to 32.5 MPa. This is because the asymmetric structure of the hydroxyl-terminated polybutadiene resin disrupts the crystallinity.

[0110] Comparing Example 1 and Comparative Examples 6-7, it can be found that changing the amount of hydroxyl-terminated fluoropolymer added to the raw materials results in a slight decrease in the dyne value of the polyurethane elastomer when the amount added is small. Although the migration reaches Grade A when the amount added is large, the impact on physical properties is significant, with a decrease in hardness and tensile strength. This is because the hydroxyl-terminated fluoropolymer has too many blocks in the entire TPU chain, leading to a decrease in the crystallinity of the macromolecular chain.

[0111] Comparing Example 1 with Comparative Examples 8-9 and 10-11, it can be found that when the molecular weight of the hydroxyl-terminated polybutadiene resin and the hydroxyl-terminated fluoropolymer in the raw materials is too large or too small, the ink will migrate, which may be related to the entanglement of molecular chains and intermolecular forces.

[0112] Comparing Example 1 and Comparative Example 12, although the hardness, dyne value and migration resistance of the product of Comparative Example 12 are similar to those of Example 1, the injection molding time is longer due to the smaller molecular weight of the polymer polyol, which is not conducive to continuous production.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A bulk polymerized TPU resistant to ink migration, characterized in that, The raw materials for the bulk polymerized ink migration-resistant TPU include the following components in parts by weight: 30-40 parts of polymeric polyol, 10-15 parts of hydroxyl-terminated polybutadiene resin, 5-8 parts of hydroxyl-terminated fluoropolymer, 30-35 parts of diisocyanate, 7-10 parts of chain extender, 2-4 parts of titanium dioxide, and additives; the number average molecular weight of the polymeric polyol is 1500-3500. The polymer polyol is a polyester polyol and / or a polyether polyol; The molecular weight of the hydroxyl-terminated polybutadiene resin is 1000-3000; The molecular weight of the hydroxyl-terminated fluoropolymer is 1000-3000.

2. The bulk polymerized ink migration-resistant TPU as described in claim 1, characterized in that, The polyester polyol includes at least one of polyethylene adipate diol, polybutylene adipate diol, and polyethylene adipate butylene diol. The polyether polyol includes polytetrahydrofuran diol.

3. The bulk polymerized ink migration-resistant TPU as described in claim 1, characterized in that, The diisocyanate includes at least one of 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; The chain extender includes at least one of C2-C10 straight-chain alkane diols.

4. The bulk polymerized ink migration-resistant TPU as described in claim 3, characterized in that, The chain extender includes at least one of 1,2-ethylene glycol, 1,4-butanediol, and 1,6-hexanediol.

5. The bulk polymerized ink migration-resistant TPU as described in claim 1, characterized in that, The adjuvant is an antioxidant and / or a catalyst; The antioxidant includes at least one of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N-bis-[3-(3,5,-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine and octadecyl 3,5-di-tert-butyl-4-hydroxyphenylpropionate; The catalyst comprises stannous octoate and / or dibutyltin dilaurate.

6. The bulk polymerized ink migration-resistant TPU as described in claim 5, characterized in that, The catalyst content in the raw materials for preparing the bulk polymerized ink migration-resistant TPU is 30-80 ppm; The mass ratio of the antioxidant to the polymer polyol is (1-2):(30-40).

7. The method for preparing bulk polymerized ink migration-resistant TPU according to any one of claims 1-6, characterized in that, The process includes the following steps: mixing polymeric polyol, hydroxyl-terminated polybutadiene resin, hydroxyl-terminated fluoropolymer, titanium dioxide, and additives evenly and placing them in container A; placing the diisocyanate in container B; placing the chain extender in container C; injecting the components from containers A, B, and C into a twin-screw extruder using a casting machine; and reacting in the twin-screw extruder to obtain the bulk polymerized ink migration-resistant TPU. The twin-screw extruder has a screw speed of 180-230 rpm and an operating temperature range of 180-210 ℃.

8. The method for preparing bulk polymerized ink migration-resistant TPU as described in claim 7, characterized in that, The temperature of container A is maintained at 95-105℃, the temperature of container B is maintained at 45-55℃, and the temperature of container C is maintained at 45-50℃. After the reaction in the twin-screw extruder is completed, underwater pelletizing and drying steps are also included; The drying temperature is 80-100℃, and the drying time is 6-9 hours.

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