A plasticizer-resistant adhesive layer polyurethane resin and its preparation method

Abstract

The present invention discloses a plasticizer-resistant adhesive layer polyurethane resin and a preparation method thereof, belonging to the technical field of polyurethane functional materials and their preparation methods. The preparation method of the polyurethane resin is as follows: Mix 60-70% of the total amount of solvent, linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and antioxidant evenly to obtain a mixture; Add 85-90% of the total amount of diisocyanate to the mixture for polymerization reaction. During the reaction process, add a catalyst, and then continue the reaction. Add the remaining diisocyanate and the remaining solvent step by step in multiple times. When the viscosity reaches 60-100 Pa·S / 25 °C, add a terminator to terminate the reaction to obtain the target product; The molecular structure of the polycarbonate diol has a cyclic structure; The mixed chain extender is composed of ethylene glycol and 1,2-propanediol with an asymmetric structure. The product prepared by the present invention has both plasticizer-resistant permeability, balanced mechanical properties and meets the requirements of automotive interior processing.

Description

Technical Field

[0001] The present 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 their preparation methods. This resin is mainly applied to automotive interior leather products. Background Art

[0002] Polyurethane (PU), whose full name is polycarbamate, is a polymer material formed by the polymerization reaction of polyols and polyisocyanates and has excellent mechanical properties, with extremely strong plasticity. Due to its excellent wear resistance, flexibility and leather-like texture, polyurethane materials are widely used in interior components such as automotive seat skins. At the same time, due to its cost advantage and processing performance, polyvinyl chloride (PVC) materials are often used as a support layer or a covering material in adjacent cooperation with PU components. 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 automobiles, affected by temperature fluctuations, mechanical stress and long-term contact, the plasticizer will gradually migrate from the PVC substrate to adjacent materials. When the plasticizer contacts the PU skin, its small molecule characteristics cause it to easily penetrate between the PU macromolecular chains, triggering a swelling effect. Swelling will cause abnormal surface gloss, texture deformation, bulging and even cracking of the PU material, seriously affecting the aesthetics and service life of the product. This problem is particularly significant in the high-temperature and high-humidity interior environment of vehicles.

[0003] In the prior art, to solve the problem of PU's resistance to plasticizers, the following solutions are mainly adopted: (1) By increasing the cross-linking density of PU to reduce the plasticizer penetration rate, but this method will increase the brittleness of the material and cannot meet the requirements of automotive seats for flexibility and flex resistance; (2) Adopting a full substitution solution (such as TPU materials), but the cost increases significantly and the processing performance deteriorates, etc.

[0004] In summary, developing a PU resin material that combines plasticizer penetration resistance, balanced mechanical properties (such as wear resistance, cold resistance, normal temperature flex resistance, flame retardancy, etc.) and meets the processing requirements of automotive interiors has become an urgent technical problem to be solved in this field. Summary of the Invention

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

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A plasticizer-resistant adhesive layer polyurethane resin and its preparation method are prepared according to the following steps:

[0008] Mix 60 - 70% of the total solvent, linear polyester diol, polyether diol, polycarbonate diol, and a mixed chain extender and antioxidant evenly; add 85 - 90% of the total amount of diisocyanate to the mixed material for polymerization reaction. After reacting at 70 - 80 °C for 30 min, add a catalyst and continue to react for 20 - 30 min;

[0009] Add the remaining diisocyanate in multiple steps to increase the reaction viscosity. As the viscosity of the system continuously increases, gradually add the remaining solvent. When the solid content reaches 35 ± 1% and the viscosity reaches 60 - 100 Pa·S / 25 °C, stop adding the diisocyanate and add a terminator to terminate the reaction.

[0010] Among them:

[0011] The mixed chain extender is mainly ethylene glycol and supplemented by 1,2 - propanediol with an asymmetric structure; the mass ratio of ethylene glycol to 1,2 - propanediol is (5 - 7):1. When the mass ratio of ethylene glycol to 1,2 - propanediol is greater than 7:1, ethylene glycol has strong crystallinity, and the resin film - forming speed is fast during hot processing, reducing the adhesive performance of the resin; when the mass ratio of ethylene glycol to 1,2 - propanediol is less than 5:1, 1,2 - propanediol has an asymmetric structure, which will affect the regularity of the resin structure, thus reducing the cold resistance and flex resistance of the resin.

[0012] 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 performance of the resin but also improves the bonding fastness 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 hot processing, and the hot - bonding property is strong, so the bonding fastness between the resin and the solvent - free layer can be improved.

[0013] The linear polyester diol is polyethylene glycol - 1,4 - butanediol adipate diol, which has good flexibility. The molecular weight of the linear polyester diol is 2000 ± 200, which improves the bonding force between the synthesized resin and the surface - layer solvent - type polyurethane resin and the plasticizer - resistance performance;

[0014] The molecular weight of the polyether diol is 1000 ± 200, which reduces the crystallinity and hardness of the synthesized resin and improves the adhesive performance, cold resistance, and hydrolysis - resistance performance of the resin

[0015] Further, the mass ratio of the linear polyester diol, polyether diol, and polycarbonate diol is (85-110):(70-80):(15-30). Through experiments, the present invention designs the ratio between various diols, fully considering the influence of different soft segment structures of polyurethane resins on performance, and obtains a polyurethane resin product with excellent comprehensive performance.

[0016] In the above steps, the water content of the linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender, and solvent involved is required to be less than 500 ppm.

[0017] The present invention also provides a plasticizer-resistant adhesive layer polyurethane resin prepared by the above preparation method.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] The preparation method of the plasticizer-resistant adhesive layer polyurethane resin provided by the present invention designs the ratio between the linear polyester diol, polyether diol, and polycarbonate diol, fully considering the influence of different soft segment structures of polyurethane resins on performance; and by using a substance composed of ethylene glycol and 1,2-propanediol with an asymmetric structure as a mixed chain extender to reduce the crystallinity of the hard segment, which is beneficial to improving the adhesive performance of the resin; at the same time, during the reaction process, raw materials such as the linear polyester diol, polyether diol, polycarbonate diol, and mixed chain extender are put into the reaction system at one time and directly react under a high-temperature environment to generate polyurethane resin. Compared with the prepolymer method of the prior art, the synthesis method provided by the present invention can reduce the phase separation degree of the hard and soft segments in the resin structure, which is beneficial to improving the adhesive performance with the solvent-based surface layer polyurethane resin and the solvent-free bottom layer polyurethane resin. Specific Embodiments

[0020] The following examples are used to further illustrate the present invention, so that those skilled in the art can better understand the present invention and implement it, but the examples given are not intended to limit the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the description of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. In addition, unless otherwise specified, the methods without specific conditions or steps recorded are conventional methods, and the reagents and materials used can be obtained from commercial sources.

[0022] The specific information of the main raw materials used in the following examples and comparative examples is as follows:

[0023] The diisocyanate is diphenylmethane diisocyanate;

[0024] The linear polyester diol is ethylene glycol-1,4-butanediol adipate diol with a molecular weight of 2000±200;

[0025] The polyether diol: model is PTMG-1000, and the supplier is Hangzhou Sanlong New Materials Co., Ltd.;

[0026] The polycarbonate diol: model is PC-90, and the supplier is Guangdong Dongguan Hongsui Industry Co., Ltd.

[0027] It should be noted that the above raw materials are only for explaining the reagent sources and components used in the experiments of the present invention for full disclosure, and do not mean that the present invention cannot be realized by using other similar reagents or reagents provided by other suppliers.

[0028] Example 1

[0029] The raw material composition of a polyurethane resin resistant to plasticizer adhesion layer is as shown in Table 1 below:

[0030] Table 1

[0031]

[0032] The preparation method of the polyurethane resin is specifically carried out according to the following steps:

[0033] (1) Mix 70% of the total amount of the solvent (N,N-dimethylformamide), ethylene glycol-1,4-butanediol adipate diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propanediol, antioxidant, etc. evenly; add 85% of the total amount of diphenylmethane diisocyanate to the mixed material for polymerization reaction, add a catalyst after reacting at 70~80°C for 30 min, and continue to react for 30 min;

[0034] (2) Gradually add the remaining diphenylmethane diisocyanate in several times to increase the reaction viscosity. As the viscosity of the system continues to increase, gradually add the remaining solvent. When the solid content reaches 35±1% and the viscosity reaches 60~100 Pa·S / 25°C, add a methanol terminator to terminate the reaction.

[0035] Comparative Example 1

[0036] The raw material composition of a polyurethane resin is as shown in Table 2 below:

[0037] Table 2

[0038]

[0039] The preparation method of this scheme is the same as the steps of Example 1 above.

[0040] The performance comparison test of the polyurethane resins obtained in Example 1 and Comparative Example 1 after leather making is shown in Table 3 below:

[0041] Table 3

[0042]

[0043] 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 to the soft segment not only improves the plasticizer resistance of the resin, but also improves the adhesion fastness between the resin and the solvent-free bottom layer.

[0044] Note: The method for testing the plasticizer resistance performance is as follows. Cut a test sample of 10 cm * 10 cm, place it on a glass plate with the leather surface facing up, place a 3 cm * 3 cm PVC sheet with the leather surface facing down at the center of the test sample, apply a pressure of 5 kg at the same time, place it in an oven at 105 °C, take it out after 40 min, remove the pressure, and cool it at (23 ± 2) °C for 24 h, and observe the surface condition of the specimen.

[0045] Example 2

[0046] The raw material composition of a polyurethane resin with plasticizer resistance and adhesion layer is as follows in Table 4:

[0047] Table 4

[0048]

[0049] The preparation method of the polyurethane resin is specifically carried out according to the following steps:

[0050] Mix 70% of the total amount of solvent (N,N-dimethylformamide), polyethylene glycol adipate-1,4-butanediol ester diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propanediol, antioxidant, etc. evenly; add 90% of the total amount of diphenylmethane diisocyanate to the mixed material for polymerization reaction, add a catalyst after reacting at 70 - 80 °C for 30 min, and continue to react for 30 min;

[0051] Add the remaining diphenylmethane diisocyanate in several steps gradually to increase the reaction viscosity. As the viscosity of the system increases continuously, add the remaining solvent gradually. When the solid content reaches 35 ± 1% and the viscosity reaches 60 - 100 Pa·S / 25 °C, add a methanol terminator to terminate the reaction.

[0052] Comparative Example 2

[0053] The raw material composition of a polyurethane resin is as follows in Table 5:

[0054] Table 5

[0055]

[0056] The preparation method of this solution is the same as the steps of Example 2 above.

[0057] After the leather was made from the resins synthesized in the above two Examples 2 and Comparative Example 2, performance comparison tests were carried out, and the results are shown in Table 6:

[0058] Table 6

[0059]

[0060] It can be seen from the comparison between Example 2 and Comparative Example 2 in Table 6 above that adding an appropriate amount of asymmetric structure 1,2-propanediol to the chain extender has little effect on the plasticizer resistance performance of the resin, but can improve the adhesion strength between the resin and the solvent-free bottom layer.

[0061] Example 3

[0062] The raw material composition of a polyurethane resin with plasticizer resistance and adhesion layer is as follows in Table 7:

[0063] Table 7

[0064]

[0065] The preparation method of the polyurethane resin is specifically carried out according to the following steps:

[0066] (1) Mix 70% of the total amount of the solvent (N,N-dimethylformamide), polyethylene glycol adipate-1,4-butanediol ester diol, PTMG-1000, PC-90, ethylene glycol, 1,2-propanediol, antioxidant, etc. evenly; add 90% of the total amount of diphenylmethane diisocyanate to the mixed material for polymerization reaction, add a catalyst after reacting at 70-80 °C for 30 min, and continue to react for 30 min;

[0067] (2) Add the remaining diphenylmethane diisocyanate in several steps to increase the reaction viscosity. As the viscosity of the system increases continuously, gradually add the remaining solvent. When the solid content reaches 35 ± 1% and the viscosity reaches 60-100 Pa·S / 25 °C, add a methanol terminator to terminate the reaction.

[0068] Comparative Example 3

[0069] The raw material composition of a polyurethane resin is as follows in Table 8:

[0070] Table 8

[0071]

[0072] The preparation method of the polyurethane resin is carried out by the following prepolymerization method, specifically according to the following steps:

[0073] (1) Mix 60% of the total amount of the solvent (N,N-dimethylformamide), polyethylene glycol-1,4-butanediol adipate diol, PTMG-1000, PC-90, and antioxidant evenly; add 90% of the total amount of diphenylmethane diisocyanate to the mixed materials for prepolymerization reaction. After reacting for 30 min at 70 - 80 °C, add a catalyst and continue the reaction; control the prepolymer viscosity within the range of 20 - 30 Pa·S / 70 - 80 °C.

[0074] (2) Then add ethylene glycol and 1,2-propanediol, and gradually add the remaining diphenylmethane diisocyanate in multiple steps to increase the reaction viscosity. As the viscosity of the system continuously increases, gradually add the remaining solvent. When the solid content reaches 35 ± 1% and the viscosity reaches 60 - 100 Pa·S / 25 °C, add a methanol terminator to terminate the reaction.

[0075] After the leather is made from the resins synthesized in the above two Examples 3 and Comparative Example 3, performance comparison tests are carried out. The results are shown in Table 9:

[0076] Table 9

[0077]

[0078] It can be seen from the comparison between Example 3 and Comparative Example 3 in the above Table 9 that the different synthesis processes of the one-step method and the prepolymer method in the present invention have little effect on the plasticizer resistance performance of the resin, but the one-step method process can reduce the phase separation degree of the hard and soft segments, which is beneficial to improving the adhesion performance with solvent-based surface layer polyurethane resin and solvent-free bottom layer polyurethane resin.

[0079] Comparative Example 4

[0080] The raw material composition of a plasticizer-resistant adhesive layer polyurethane resin is as shown in Table 10 below:

[0081] Table 10

[0082]

[0083] The preparation method of the polyurethane resin is specifically carried out according to the following steps:

[0084] (1) Mix 70% of the total amount of the solvent (N,N-dimethylformamide), SP-2013, PTMG-1000, PC-90, ethylene glycol, 1,2-propanediol, and antioxidant, etc. evenly; add 90% of the total amount of diphenylmethane diisocyanate to the mixed materials for polymerization reaction. After reacting for 30 min at 70 - 80 °C, add a catalyst and continue the reaction for 30 min;

[0085] (2) Add the remaining diphenylmethane diisocyanate step by step in multiple times to increase the reaction viscosity. As the viscosity of the system continuously increases, gradually add the remaining solvent. When the solid content reaches 35 ± 1% and the viscosity reaches 60 - 100 Pa·S / 25°C, add methanol terminator to terminate the reaction.

[0086] After making leather from the resins synthesized in the above two Examples 3 and 4, conduct performance comparison tests. The results are shown in Table 11:

[0087] Table 11

[0088]

[0089] It can be seen from the test comparison between Example 3 and Comparative Example 4 in the above Table 11 that when the addition amount of the cyclic polycarbonate diol in the soft segment reaches 40 kg, the resin has good plasticizer resistance performance and adhesion performance, but the cold resistance significantly decreases after making leather, and it can no longer meet the processing requirements of automotive interior leather.

[0090] In summary, for a polyurethane resin for a plasticizer-resistant adhesive layer and its preparation method provided by the present invention, the soft segment used is a mixture composed of linear polyester diol, polyether diol, and polycarbonate diol. Different soft segment structures determine different properties, which is beneficial to balancing the plasticizer resistance permeability and mechanical properties and meeting the requirements of automotive interior processing; using a mixture of small molecule diols composed of ethylene glycol and asymmetric 1,2-propanediol as the chain extender to reduce the crystallinity of the hard segment is beneficial to improving the adhesion performance of the resin; at the same time, adopting a one-step synthesis process to reduce the phase separation degree of the hard and soft segments is beneficial to improving the adhesion performance with solvent-based surface layer resin and solvent-free bottom layer resin at the same time.

[0091] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described comprehensively. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0092] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A preparation method of a plasticizer-resistant adhesive layer polyurethane resin, characterized in that: It includes the following steps: Mix 60 - 70% of the total amount of solvent, linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and antioxidant evenly to obtain a mixture; add 85 - 90% of the total amount of diisocyanate to the mixture for polymerization reaction, add a catalyst during the reaction process, then continue the reaction, gradually add the remaining diisocyanate and the remaining solvent in multiple portions. When the viscosity reaches 60 - 100 Pa·S / 25°C, add a terminator to terminate the reaction to obtain the target product; The molecular structure of the polycarbonate diol has a cyclic structure; the mixed chain extender is composed of ethylene glycol and 1,2 - propanediol with an asymmetric structure; The mass ratio of ethylene glycol to 1,2 - propanediol in the mixed chain extender is (5 - 7):1; The polycarbonate diol is PC - 90, its supplier is Guangdong Dongguan Hongsui Industry Co., Ltd., and the molecular weight of the polycarbonate diol is 900 ± 100; The mass ratio of the linear polyester diol, polyether diol, and polycarbonate diol is (85 - 110):(70 - 80):(15 - 30); The molecular weight of the polyether diol is 1000 ± 200; The linear polyester diol is ethylene glycol - 1,4 - butanediol adipate diol.

2. The preparation method of the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, characterized in that: The molecular weight of the linear polyester diol is 2000 ± 200.

3. The preparation method of the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, wherein: The temperature of the polymerization reaction is 70 - 80°C.

4. The preparation method of the plasticizer-resistant adhesive layer polyurethane resin according to claim 1, wherein: The water content of the linear polyester diol, polyether diol, polycarbonate diol, mixed chain extender and solvent is required to be less than 500 ppm.

5. A plasticizer-resistant adhesive layer polyurethane resin, characterized in that: The plasticizer - resistant adhesive layer polyurethane resin is prepared by the preparation method described in any one of claims 1 to 4.

Images