Plasticizer-resistant bonding layer polyurethane resin and preparation method thereof

Abstract

The invention discloses plasticizer-resistant bonding layer polyurethane resin and a preparation method thereof, and belongs to the technical field of polyurethane functional materials and preparation methods thereof. The preparation method of the polyurethane resin comprises the following steps: uniformly mixing a solvent accounting for 60-70% of the total amount of the solvent, straight-chain polyester diol, polyether diol, polycarbonate diol, a mixed chain extender and an antioxidant to obtain a mixture; and adding 85-90% of the total amount of diisocyanate into the mixture, carrying out a polymerization reaction, adding a catalyst in the reaction process, continuing the reaction, gradually adding the residual diisocyanate and the residual solvent for multiple times, and adding a terminating agent to terminate the reaction when the viscosity reaches 60-100 Pa.S / 25 DEG C, so as to obtain a target product. The molecular structure of the polycarbonate diol has an annular structure; the mixed chain extender is formed by mixing ethylene glycol and 1, 2-propylene glycol with an asymmetric structure. The product prepared by the invention has the advantages of plasticizer permeability resistance and balanced mechanical properties, and meets the processing requirements of automotive interiors.

Description

Technical Field

[0001] The invention relates to a plasticizer-resistant adhesive layer polyurethane resin and a preparation method thereof, belonging to the technical field of polyurethane functional materials and preparation methods thereof. The resin is mainly used in automotive interior leather products. Background Art

[0002] Polyurethane (PU), whose full name is polyurethane, is a polymer material with excellent mechanical properties and strong plasticity formed by the polymerization reaction of polyols and polyisocyanates. Polyurethane materials are widely used in interior parts such as car seat surfaces due to their excellent wear resistance, flexibility and leather-like feel. At the same time, polyvinyl chloride (PVC) materials are often used as support layers or coating materials adjacent to PU components due to their cost advantages and processing performance. However, PVC materials usually contain 20%-40% plasticizers (such as dibutyl phthalate (DBP), dioctyl phthalate (DOP), diisobutyl phthalate (DIBP), diisononyl phthalate (DINP), etc.). During the use of the car, the plasticizer will gradually migrate from the PVC substrate to the adjacent material due to temperature fluctuations, mechanical stress and long-term contact. When the plasticizer comes into contact with the PU surface, its small molecular characteristics make it easy to penetrate into the PU macromolecular chains, causing a swelling effect. Swelling can cause abnormal gloss, texture deformation, bulging and even cracking of the PU material surface, seriously affecting the appearance and service life of the product. This problem is particularly prominent in the high temperature and high humidity environment of the car.

[0003] In the prior art, the following solutions are mainly used to solve the problem of PU resistance to plasticizers: (1) Increasing the cross-linking density of PU to reduce the plasticizer permeability, but this method will increase the brittleness of the material and cannot meet the requirements of automotive seats for flexibility and flexural resistance; (2) Using a full replacement solution (such as TPU material), but the cost will increase significantly and the processing performance will deteriorate.

[0004] In summary, developing a PU resin material that has resistance to plasticizer penetration, balanced mechanical properties (such as wear resistance, cold resistance, room temperature flexibility, flame retardancy, etc.) and meets the requirements of automotive interior processing has become a technical problem that urgently needs to be overcome in this field. Summary of the invention

[0005] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art and provide a plasticizer-resistant adhesive layer polyurethane resin and a preparation method thereof, which require resistance to plasticizer penetration, balance of mechanical properties and compliance with automotive interior processing requirements, as well as good hydrolysis resistance.

[0006] The objective of the present invention is achieved through the following technical solutions: A plasticizer-resistant adhesive layer polyurethane resin and a preparation method thereof are prepared according to the following steps: 60-70% of the total solvent, straight-chain polyester diol, polyether diol, polycarbonate diol, mixed chain extender and antioxidant are mixed evenly; 85-90% of the total diisocyanate is added to the mixture for polymerization reaction, and after reacting at 70-80°C for 30 minutes, a catalyst is added and the reaction is continued for 20-30 minutes; The remaining diisocyanate is added gradually in multiple times to increase the reaction viscosity. As the viscosity of the system continues to increase, the remaining solvent is added gradually. When the solid content reaches 35±1% and the viscosity reaches 60~100Pa.S / 25℃, the addition of diisocyanate is stopped and a terminator is added to terminate the reaction.

[0007] in: The mixed chain extender is mainly composed of ethylene glycol and supplemented by 1,2-propylene glycol with an asymmetric structure; the mass ratio of ethylene glycol to 1,2-propylene glycol is (5-7):1. When the mass ratio of ethylene glycol to 1,2-propylene glycol is greater than 7:1, ethylene glycol has strong crystallinity, the resin film-forming speed is fast during heat processing, and the bonding performance of the resin is reduced; when the mass ratio of ethylene glycol to 1,2-propylene glycol is less than 5:1, 1,2-propylene glycol is an asymmetric structure, which will affect the regularity of the resin structure, thereby reducing the cold resistance and flexibility of the resin.

[0008] The polycarbonate diol has a cyclic structure in its molecular structure; preferably, the polycarbonate diol is PC-90, and the molecular weight of the polycarbonate diol is 900±100. The polycarbonate with a cyclic structure has excellent adhesion, which not only improves the plasticizer resistance of the resin, but also improves the bonding strength between the resin and the solvent-free layer; due to the cyclic structure, the intermolecular force is large and the polarity is strong; at the same time, the molecular weight is small, the resin film-forming speed is slow during heat processing, and the thermal adhesiveness is strong, so the bonding strength between the resin and the solvent-free layer can be improved.

[0009] The linear polyester diol is polyethylene adipate glycol-1,4-butylene glycol ester diol, which has good flexibility, and the molecular weight of the linear polyester diol is 2000±200, which improves the bonding strength of the synthesized resin with the surface solvent-based polyurethane resin and the plasticizer resistance performance; The molecular weight of the polyether diol is 1000±200, which reduces the crystallinity and hardness of the synthesized resin and improves the bonding performance, cold resistance and hydrolysis resistance of the resin. In a further embodiment, the mass ratio of the linear polyester diol, the polyether diol, and the polycarbonate diol is (85-110): (70-80): (15-30). The present invention designs the ratio between various diols through experiments, fully considers the influence of different soft segment structures of polyurethane resin on the performance, and obtains a polyurethane resin product with excellent comprehensive performance.

[0010] The linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and solvent involved in the above steps are all required to have a water content of less than 500 ppm.

[0011] The present invention also provides a plasticizer-resistant adhesive layer polyurethane resin prepared by the above preparation method.

[0012] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of the plasticizer-resistant adhesive layer polyurethane resin provided by the present invention fully considers the influence of different soft segment structures of polyurethane resin on performance by designing the ratio between linear polyester diol, polyether diol and polycarbonate diol; and uses a substance composed of ethylene glycol and 1,2-propylene glycol with an asymmetric structure as a mixed chain extender to reduce the crystallinity of the hard segment, which is beneficial to improve the bonding performance of the resin; at the same time, during the reaction process, the linear polyester diol, polyether diol, polycarbonate diol and mixed chain extender and other raw materials are put into the reaction system at one time, and directly reacted under a high temperature environment to generate polyurethane resin. Compared with the prepolymerization method of the prior art, the synthesis method provided by the present invention can reduce the degree of phase separation of soft and hard segments in the resin structure, which is beneficial to improve the bonding performance with solvent-based surface layer polyurethane resin and solvent-free bottom layer polyurethane resin. DETAILED DESCRIPTION

[0013] The present invention is further described below in conjunction with the embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In addition, unless otherwise specified, methods that do not specifically record conditions or steps are conventional methods, and the reagents and materials used can be obtained from commercial sources.

[0015] The main raw materials used in the following examples and comparative examples are as follows: The diisocyanate is diphenylmethane diisocyanate; The linear polyester diol is polyethylene adipate-1,4-butylene glycol ester diol, with a molecular weight of 2000±200; Polyether diol: model PTMG-1000, supplier is Hangzhou Sanlong New Materials Co., Ltd.; Polycarbonate diol: model is PC-90, and the supplier is Guangdong Dongguan Longsui Industrial Co., Ltd.

[0016] It should be noted that the above raw materials are only for illustrating the sources and components of the reagents used in the experiments of the present invention so as to fully disclose the information, and do not mean that the present invention cannot be achieved by using other similar reagents or reagents provided by other suppliers.

[0017] Example 1 The raw material composition of a plasticizer-resistant adhesive layer polyurethane resin is as follows in Table 1: Table 1

[0018] The preparation method of polyurethane resin is specifically carried out according to the following steps: (1) Evenly mix 70% of the total solvent (N,N-dimethylformamide), polyethylene glycol-1,4-butylene adipate diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propylene glycol and antioxidant; add 85% of the total diphenylmethane diisocyanate to the mixture for polymerization reaction, add a catalyst after reacting at 70-80°C for 30 minutes, and continue the reaction for 30 minutes; (2) Add the remaining diphenylmethane diisocyanate gradually in multiple times to increase the reaction viscosity. As the viscosity of the system continues to increase, add the remaining solvent gradually. When the solid content reaches 35±1% and the viscosity reaches 60~100Pa.S / 25℃, add methanol terminator to terminate the reaction.

[0019] Comparative Example 1 The raw material composition of a polyurethane resin is as shown in Table 2: Table 2

[0020] The preparation method of this scheme is specifically the same as the steps in Example 1 above.

[0021] The performance comparison of the polyurethane resins prepared in Example 1 and Comparative Example 1 after leather formation is shown in Table 3: Table 3

[0022] From the test comparison of Example 1 and Comparative Example 1 in Table 3 above, it can be seen that adding polycarbonate diol with a cyclic structure in the soft segment not only improves the plasticizer resistance of the resin, but also improves the bonding strength between the resin and the solvent-free base layer.

[0023] Note: The test method for plasticizer resistance is as follows: cut a test sample of 10cm*10cm, place it on a glass plate with the leather side facing up, and place a 3cm*3cm PVC sheet with the leather side facing down in the center of the test sample. Apply 5kg pressure at the same time and place it in a 105℃ oven. Take it out after 40 minutes and remove the pressure. Cool it at (23±2)℃ for 24 hours and observe the surface condition of the sample.

[0024] Example 2 The raw material composition of a plasticizer-resistant adhesive layer polyurethane resin is as shown in Table 4: Table 4

[0025] The preparation method of polyurethane resin is specifically carried out according to the following steps: 70% of the total solvent (N,N-dimethylformamide), polyethylene glycol-1,4-butylene adipate diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propylene glycol and antioxidant were mixed evenly; 90% of the total diphenylmethane diisocyanate was added to the mixture for polymerization reaction, and the catalyst was added after the reaction at 70-80°C for 30 minutes, and the reaction was continued for 30 minutes; The remaining diphenylmethane diisocyanate was gradually added in multiple times to increase the reaction viscosity. As the viscosity of the system continued to increase, the remaining solvent was gradually added. When the solid content reached 35±1% and the viscosity reached 60~100Pa.S / 25℃, methanol terminator was added to terminate the reaction.

[0026] Comparative Example 2 The raw material composition of a polyurethane resin is as shown in Table 5: Table 5

[0027] The preparation method of this scheme is specifically the same as the steps in Example 2 above.

[0028] The resins synthesized in the above two examples 2 and comparative example 2 were made into leather and then subjected to performance comparison tests. The results are shown in Table 6: Table 6

[0029] From the comparison between Example 2 and Comparative Example 2 in Table 6 above, it can be seen that adding an appropriate amount of asymmetric 1.2-propylene glycol to the chain extender has little effect on the plasticizer resistance of the resin, but can improve the bonding strength between the resin and the solvent-free base layer.

[0030] Example 3 The raw material composition of a plasticizer-resistant adhesive layer polyurethane resin is as shown in Table 7: Table 7

[0031] The preparation method of polyurethane resin is specifically carried out according to the following steps: (1) Evenly mix 70% of the total solvent (N,N-dimethylformamide), polyethylene glycol-1,4-butylene adipate diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propylene glycol and antioxidant; add 90% of the total diphenylmethane diisocyanate to the mixture for polymerization reaction, react at 70-80°C for 30 minutes, then add a catalyst and continue the reaction for 30 minutes; (2) Add the remaining diphenylmethane diisocyanate gradually in multiple times to increase the reaction viscosity. As the viscosity of the system continues to increase, add the remaining solvent gradually. When the solid content reaches 35±1% and the viscosity reaches 60~100Pa.S / 25℃, add methanol terminator to terminate the reaction.

[0032] Comparative Example 3 The raw material composition of a polyurethane resin is shown in Table 8 below: Table 8

[0033] The preparation method of the polyurethane resin is carried out by the following prepolymerization method, which is specifically carried out according to the following steps: (1) 60% of the total amount of solvent (N,N-dimethylformamide), polyethylene adipate glycol-1,4-butylene glycol ester diol, PTMG-1000, PC-90 and antioxidant are mixed evenly; 90% of the total amount of diphenylmethane diisocyanate is added to the mixture for prepolymerization reaction, and after reacting at 70-80°C for 30 minutes, a catalyst is added to continue the reaction; the prepolymerization viscosity is controlled within the range of 20-30 Pa.S / 70-80°C.

[0034] (2) Then, ethylene glycol and 1,2-propylene glycol were added, and the remaining diphenylmethane diisocyanate was gradually added in multiple times to increase the reaction viscosity. As the viscosity of the system continued to increase, the remaining solvent was gradually added. When the solid content reached 35±1% and the viscosity reached 60~100 Pa.S / 25°C, methanol terminator was added to terminate the reaction.

[0035] The resins synthesized in the above two examples 3 and comparative example 3 were made into leather and then subjected to performance comparison tests. The results are shown in Table 9: Table 9

[0036] From the comparison between Example 3 and Comparative Example 3 in Table 9 above, it can be seen that the different synthesis processes of the one-step method and the prepolymerization method in the present invention have little effect on the plasticizer resistance of the resin, but the one-step process can reduce the degree of phase separation between the soft and hard segments, which is beneficial to improving the bonding performance with the solvent-based surface polyurethane resin and the solvent-free bottom polyurethane resin.

[0037] Comparative Example 4 The raw material composition of a plasticizer-resistant adhesive layer polyurethane resin is as shown in Table 10: Table 10

[0038] The preparation method of polyurethane resin is specifically carried out according to the following steps: (1) Evenly mix 70% of the total solvent (N,N-dimethylformamide), SP-2013, PTMG-1000, PC-90, ethylene glycol, 1,2-propylene glycol and antioxidant; add 90% of the total diphenylmethane diisocyanate to the mixture for polymerization reaction, add catalyst after reacting at 70-80°C for 30 minutes, and continue the reaction for 30 minutes; (2) Add the remaining diphenylmethane diisocyanate gradually in multiple times to increase the reaction viscosity. As the viscosity of the system continues to increase, add the remaining solvent gradually. When the solid content reaches 35±1% and the viscosity reaches 60~100Pa.S / 25℃, add methanol terminator to terminate the reaction.

[0039] The resins synthesized in the above two embodiments 3 and 4 were made into leather and then the performance was compared and tested. The results are shown in Table 11: Table 11

[0040] From the test comparison of Example 3 and Comparative Example 4 in Table 11 above, it can be seen that when the addition amount of the cyclic polycarbonate diol in the soft segment reaches 40 kg, the plasticizer resistance and bonding properties of the resin are good, but the cold resistance of the finished leather is significantly reduced, and it can no longer meet the processing requirements of automotive interior leather.

[0041] In summary, the present invention provides a plasticizer-resistant adhesive layer polyurethane resin and a preparation method thereof, wherein the soft segment used is a mixture of linear polyester diols, polyether diols, and polycarbonate diols, and different soft segment structures determine different performances, which is beneficial to taking into account the balance between plasticizer permeability resistance and mechanical properties and meeting the requirements of automotive interior processing; a small molecule diol mixture composed of ethylene glycol and 1,2-propylene glycol with an asymmetric structure is used as a chain extender to reduce the crystallinity of the hard segment, which is beneficial to improving the bonding performance of the resin; and a one-step synthesis process is used to reduce the degree of phase separation between the soft and hard segments, which is beneficial to simultaneously improve the bonding performance with the solvent-based surface layer resin and the solvent-free base layer resin.

[0042] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are fully described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0043] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a plasticizer-resistant adhesive layer polyurethane resin, characterized in that: The following steps are involved: 60-70% of the total solvent, linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and antioxidant are uniformly mixed to obtain a mixture; 85-90% of the total diisocyanate is added to the mixture for polymerization reaction, a catalyst is added during the reaction, and then the reaction is continued, and the remaining diisocyanate and the remaining solvent are gradually added in multiple times, and when the viscosity reaches 60-100 Pa.S / 25°C, a terminator is added to terminate the reaction to obtain a target product; The molecular structure of the polycarbonate diol has a cyclic structure; the mixed chain extender is composed of a mixture of ethylene glycol and 1,2-propylene glycol with an asymmetric structure; The mass ratio of ethylene glycol to 1,2-propylene glycol in the mixed chain extender is (5-7):1; The polycarbonate diol is PC-90, and the molecular weight of the polycarbonate diol is 900±100.

2. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The linear polyester diol is polyethylene adipate glycol-1,4-butylene adipate diol.

3. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 2, characterized in that: The molecular weight of the linear polyester diol is 2000±200.

4. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The mass ratio of the linear polyester diol, the polyether diol and the polycarbonate diol is (85-110): (70-80): (15-30).

5. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The molecular weight of the polyether diol is 1000±200.

6. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The polymerization reaction temperature is 70-80°C.

7. The method for preparing the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and solvent are all required to have a water content of less than 500 ppm.

8. A plasticizer-resistant adhesive layer polyurethane resin, characterized in that: The plasticizer-resistant adhesive layer polyurethane resin is prepared by the preparation method according to any one of claims 1 to 7.

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