Polyurethane resin, polyurethane synthetic leather, preparation method and application

Abstract

The invention provides polyurethane resin, polyurethane synthetic leather as well as a preparation method and application. The polyurethane resin is prepared from a hard segment component and a soft segment component through reaction, the raw materials of the hard segment component comprise diisocyanate and a small molecule chain extender, and the raw material of the soft segment component is organic silicon dihydric alcohol. The polyurethane resin disclosed by the invention can solve the problem of color development of synthetic leather, so that the synthetic leather is good in overall color uniformity, has good mechanical properties and can be widely applied to clothes, bags and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials and relates to a polyurethane resin, polyurethane synthetic leather, and a preparation method and application thereof. Background Art

[0002] Polyurethane synthetic leather has been developed for many years, and because of its good wear resistance, colorability and easy maintenance, it is widely used in clothing, bags, shoes and sports equipment. However, compared with genuine leather, it has the problem of poor color development. Color development refers to the overall color uniformity and color difference variation degree of the leather surface after the polyurethane resin after adding dye is prepared into synthetic leather, thereby limiting its application in high-end products. The most important thing to improve the color development of polyurethane resin is to improve the uniform dispersion of dye in resin. The general method in the prior art is to add a color developer to the resin to reduce the viscosity of the color paste, reduce the agglomeration of dyes, and improve the dispersion of dyes. For example, the polyurethane resins for different types of synthetic leather disclosed in patents CN105330815A and CN103145930A all have color developers added to improve the color development effect. However, the molecular weight of the color developer is much smaller than that of polyurethane resin, and there are differences in compatibility. It is difficult to achieve the desired color development effect with too little addition, and the color development effect is affected by too large addition and easy migration and precipitation. CN11303369B discloses that adding a free agent in the later stage of the reaction on the basis of polyurethane can significantly improve the color development effect, and no dye precipitation or color will occur after long-term use. This patent also improves the color development effect by using auxiliary agents.

[0003] Therefore, in this field, solving the color development effect by using additives will bring new problems. How to solve the color development problem starting from the polyurethane itself is a technology that this field wants to break through. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a polyurethane resin, polyurethane synthetic leather, and a preparation method and application thereof. The present invention solves the color development problem of synthetic leather by designing the molecular structure of polyurethane itself, so that the overall color uniformity of synthetic leather is good.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] On the one hand, the present invention provides a polyurethane resin, which is prepared by reacting a hard segment component and a soft segment component; the raw materials of the hard segment component include diisocyanate and a small molecule chain extender, and the raw materials of the soft segment component are silicone diols.

[0007] In the present invention, the hard segment component of the polyurethane resin includes diisocyanate and a small molecule chain extender, which has a strong hydrogen bond adsorption effect on the pigment. However, in the preparation process of colored polyurethane synthetic leather, the pigment will flocculate, resulting in poor color development. In the prior art, additives are generally added to solve the color development problem of synthetic leather. The inventors designed the soft segment component of the polyurethane resin to be an organosilicon segment formed only by organosilicon diols, and utilized the polarity difference between the soft segment component and the hard segment component, so that the organosilicon segment plays a role in wetting, dispersing and steric hindrance, which not only promotes the dispersion of the pigment but also provides a sufficiently thick barrier to prevent the pigment from flocculating, thereby making the color development of the synthetic leather good.

[0008] Preferably, the raw materials for preparing the polyurethane resin include the following components by weight percentage:

[0009]

[0010] In the raw materials for preparing the polyurethane resin of the present invention, the content of the organosilicon diol can be 40%, 43%, 45%, 48%, 50%, 53%, 55%, 58%, 60%, 65%, 70%, 75%, 80%, 83% or 85%, the content of the diisocyanate A can be 8%, 10%, 13%, 15%, 18%, 20%, 23%, 25% or 28%; the content of the diisocyanate B can be 5%, 8%, 10%, 13%, 15%, 18% or 20%; the content of the small molecule chain extender can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0011] Preferably, the molar ratio of the organosilicon diol to diisocyanate A is 1:1.1-2.5, such as 1:1.1, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.3 or 1:2.5. By controlling the molar ratio of the organosilicon diol to diisocyanate A, the size of the soft and hard segments can be effectively controlled, and the color development of the synthetic leather can be achieved while ensuring the mechanical properties of the synthetic leather.

[0012] Preferably, the organosilicon diol may have the following structure:

[0013]

[0014] Wherein R is selected from C1-C20 alkylene or substituted C1-C20 alkylene, the substituent in the substituted C1-C20 alkylene may be C1-C10 alkyl or C6-C20 aryl, and n is an integer of 1 to 30 (e.g., 1, 3, 5, 8, 10, 13, 15, 18, 20, 23, 25, 28 or 30, etc.).

[0015] Preferably, the molecular weight of the organosilicon diol is 1000-5000 g / mol, for example 1000 g / mol, 1300 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2500 g / mol, 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol or 5000 g / mol, preferably 1000-3000 g / mol.

[0016] It is worth noting that the present application only uses silicone with the above structure as the soft segment of the polyurethane resin to obtain the excellent color development of the synthetic leather, and studies the influence of different molecular weights. After research, the inventor found that the molecular weight of the silicone diol used as the soft segment alone will affect the color development and mechanical properties of the synthetic leather prepared by the polyurethane resin. When the molecular weight of the silicone diol is 1000-5000 g / mol, the color development of the synthetic leather is better. When the molecular weight is 4000-5000 g / mol, the mechanical properties of the synthetic leather are reduced. The inventor analyzed that the possible reason is that although the polarity difference between the silicone segment and the hard segment is large, so that the silicone segment plays a role in wetting, dispersing and steric hindrance, so that the color development is good, when the molecular weight of the silicone diol forming the silicone segment is too large, the degree of phase separation is too large, resulting in a decrease in the bonding ability of the interface between the soft and hard segments of the polyurethane, thereby causing a decrease in the mechanical properties of the synthetic leather, especially a decrease in tensile strength.

[0017] Preferably, the diisocyanate A and diisocyanate B are independently selected from one or a combination of at least two of 4,4'-diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane-4,4-diisocyanate 4,4'-dicyclohexylmethane diisocyanate (HMDI), isophorone diisocyanate (IPDI) or polymethylene polyphenyl polyisocyanate (PAPI).

[0018] In the present invention, the diisocyanate A and the diisocyanate B may be the same or different.

[0019] Preferably, the small molecule chain extender is one or a combination of at least two of ethylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol or neopentyl glycol.

[0020] Preferably, the raw materials for preparing the polyurethane resin may also include a cross-linking agent.

[0021] Preferably, the weight percentage content of the crosslinking agent in the raw materials for preparing the polyurethane resin is 0.3-1%, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or 1%.

[0022] Preferably, the cross-linking agent is an alkanetriol.

[0023] Preferably, the alkanetriol is selected from any one or a combination of at least two of glycerol, trimethylolpropane, tri(hydroxymethyl)ethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,8-octantriol, 1,2,9-nonanetriol, 1,2,10-decanetriol or 3,7,11,15-tetramethyl-1,2,3-hexanetriol; preferably any one or a combination of at least two of tri(hydroxymethyl)ethane, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,10-decanetriol or 3,7,11,15-tetramethyl-1,2,3-hexanetriol.

[0024] Preferably, the alkanetriol is selected from alkanetriols having carbon atoms ≥ 6 (e.g., 6, 7, 8, 9, 10, 12, 16, 18, 20, 23, 25, 28, etc.).

[0025] In order to solve the problem of decreased mechanical properties of synthetic leather prepared from polyurethane, the inventors added alkanetriol as a crosslinking agent to enhance the mechanical properties of synthetic leather. When glycerol and tri(hydroxymethyl)ethane were used as crosslinking agents, although the mechanical properties of synthetic leather were enhanced, the color development was reduced. The reason may be that after the crosslinking agent was used, the activity of the hard segment of the polyurethane resin was reduced, thereby affecting the hydrogen bond adsorption between it and the pigment. Therefore, the inventors tried to use a crosslinking agent with a longer chain segment. Specifically, alkanetriol was selected from carbon atoms ≥ 6, which well balanced the mechanical properties and color development properties. The possible reasons were analyzed. Alkanetriol with a certain chain length can reduce the concentration of the hard segment on the one hand, so that the degree of phase separation between the soft segment and the hard segment is weakened, and the interface bonding force between the soft and hard segments is increased. At the same time, as a physical crosslinking point, it can enhance the strength of the resin material itself. At the same time, because the crosslinking point uses alkanetriol with six carbons and above, it basically does not affect the activity of the hard segment molecular chain itself, and can maintain the hydrogen bond interaction between it and the pigment.

[0026] In a further embodiment, by controlling the molar ratio of the small molecule chain extender to the cross-linking agent to be (15-40):1, such as 15:1, 18:1, 20:1, 23:1, 25:1, 28:1, 30:1, 35:1, 38:1 or 40:1, when the molar ratio of the small molecule chain extender to the cross-linking agent is too low, the mechanical properties cannot be effectively improved. When the molar ratio of the small molecule chain extender to the cross-linking agent is too high, the polyurethane resin solution easily forms a gel and loses fluidity.

[0027] Preferably, the raw materials for preparing the polyurethane resin may further include a catalyst.

[0028] Preferably, the weight percentage content of the catalyst in the raw materials for preparing the polyurethane resin is 0.001% to 0.01%, for example, 0.001%, 0.003%, 0.005%, 0.008% or 0.01%.

[0029] Preferably, the catalyst is an organic bismuth catalyst. Preferably, the raw materials for preparing the polyurethane resin may also include a chain terminator. Preferably, the chain terminator is selected from any one of methanol, ethanol or isopropanol or a combination of at least two thereof.

[0030] Preferably, the weight percentage content of the chain terminator in the raw materials for preparing the polyurethane resin is 0.005% to 1%, for example 0.005%, 0.008%, 0.01%, 0.03%, 0.05%, 0.08%, 0.1%, 0.3%, 0.5%, 0.8% or 1%.

[0031] Preferably, the raw materials for preparing the polyurethane resin also include an antioxidant.

[0032] Preferably, the weight percentage content of the antioxidant in the raw materials for preparing the polyurethane resin is 0.01% to 1%, for example, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.1%, 0.3%, 0.5%, 0.8% or 1%.

[0033] Preferably, the antioxidant is selected from any one of hindered phenol antioxidants or phosphite antioxidants or a combination of at least two thereof.

[0034] Preferably, the raw materials for preparing the polyurethane resin also include a solvent, and the amount of the solvent is such that the mass percentage content of other raw materials except the solvent in the solvent is 30-50%, for example, 30%, 35%, 40%, 45% or 50%.

[0035] In the present invention, the content of other preparation raw materials described above except the solvent is based on the total weight of the preparation raw materials except the solvent as 100%.

[0036] Preferably, the solvent is selected from dimethylformamide and / or dimethylacetamide.

[0037] In another aspect, the present invention provides a method for preparing a polyurethane resin, the method comprising the following steps:

[0038] (1) mixing the organosilicon diol with the diisocyanate A to react;

[0039] (2) adding a small molecule chain extender to the reaction system obtained in step (1) to carry out a reaction;

[0040] (3) adding part of the solvent to the reaction system obtained in step (2), and then adding part of the diisocyanate B to react;

[0041] (4) Adding the remaining diisocyanate B and the remaining solvent to the reaction system obtained in step (3) in batches to react, and obtaining the polyurethane resin after the viscosity of the system stabilizes.

[0042] Preferably, the mixed raw materials in step (1) further include an antioxidant.

[0043] Preferably, the reaction in step (1) is a solvent-free reaction, the reaction temperature is 60-70°C (e.g., 60°C, 63°C, 65°C, 68°C or 70°C), and the reaction time is 1-2 hours (e.g., 1 hour, 1.3 hours, 1.5 hours, 1.8 hours or 2 hours).

[0044] Preferably, step (2) further comprises adding a cross-linking agent to the reaction system obtained in step (1).

[0045] Preferably, the reaction temperature in step (2) is 60-70°C (e.g., 60°C, 63°C, 65°C, 68°C or 70°C), and the reaction time is 0.5-2 hours (e.g., 0.5 hours, 1 hour, 1.3 hours, 1.5 hours, 1.8 hours or 2 hours).

[0046] Preferably, the reaction temperature in step (3) is 70-80°C (e.g., 70°C, 73°C, 75°C, 78°C or 80°C), and the reaction time is 1-2 hours (e.g., 1 hour, 1.3 hours, 1.5 hours, 1.8 hours or 2 hours).

[0047] Preferably, the partial solvent in step (3) is 20% to 50% of the total solvent, for example 20%, 22%, 25%, 30%, 35%, 40%, 45% or 50%.

[0048] Preferably, the amount of the partial diisocyanate B in step (3) is 20% to 50% of the total amount of diisocyanate B, for example 20%, 22%, 25%, 30%, 35%, 40%, 45% or 50%.

[0049] Preferably, the temperature for reacting the diisocyanate B and the solvent in batches in step (4) is 70-80°C (e.g., 70°C, 73°C, 75°C, 78°C or 80°C), and the diisocyanate B is generally added in batches in 2 to 4 times (e.g., 2, 3 or 4 times).

[0050] Preferably, the step (4) further comprises adding a catalyst to the reaction system obtained in step (3) before adding the remaining diisocyanate B and the remaining solvent in batches. Preferably, in the step (4), when the viscosity of the system increases to 8000-16000 mPa·s / 25°C, a chain terminator is optionally added, and the reaction is continued. After the viscosity of the system is stabilized, the polyurethane resin is obtained.

[0051] Preferably, the reactions in steps (1) to (4) are all carried out under stirring.

[0052] In another aspect, the present invention provides a polyurethane synthetic leather, wherein the polyurethane synthetic leather is prepared by using the polyurethane resin as described above.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] The polyurethane resin of the invention can solve the color development problem of synthetic leather, so that the overall color uniformity of the synthetic leather is good and the synthetic leather has higher mechanical properties, and can be widely used in clothing, bags and the like. DETAILED DESCRIPTION

[0055] 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.

[0056] Example 1

[0057] This embodiment provides a polyurethane resin, comprising the following raw material components in parts by weight:

[0058]

[0059] Adding solvent DMF makes the raw material content of polyurethane resin 35wt%;

[0060] Wherein, the molar ratio of the organosilicon diol to the diisocyanate A is 1:2.

[0061] Example 2

[0062] This embodiment provides a polyurethane resin, comprising the following raw material components in parts by weight:

[0063]

[0064] Adding solvent DMF makes the raw material content of polyurethane resin 40wt%;

[0065] Wherein, the molar ratio of the organosilicon diol to the diisocyanate A is 1:1.91.

[0066] Example 3

[0067] This embodiment provides a polyurethane resin, comprising the following raw material components in parts by weight:

[0068]

[0069] Adding solvent DMF makes the raw material content of polyurethane resin 45wt%;

[0070] Wherein, the molar ratio of the organosilicon diol to the diisocyanate A is 1:1.6.

[0071] Example 4

[0072] The difference from Example 1 is that an equimolar amount of organosilicon diol (Shin-Etsu KF-6003, molecular weight 5000) is used to replace the organosilicon diol in Example 1, and the rest is the same as Example 1.

[0073] Specifically:

[0074] The raw material components include the following parts by weight:

[0075]

[0076] Adding solvent DMF makes the raw material content of polyurethane resin 35wt%;

[0077] Wherein, the molar ratio of the organosilicon diol to the diisocyanate A is 1:2.

[0078] Example 5

[0079] The difference from Example 1 is that a crosslinking agent (trimethylolethane) is added, and the molar number of hydroxyl groups of the chain extender in Example 1 is the same as the molar number of hydroxyl groups of the chain extender and the crosslinking agent in Example 5, and the rest is the same as Example 1, and the weight parts of each raw material are:

[0080]

[0081] Adding solvent DMF makes the raw material content of polyurethane resin 35wt%;

[0082] The molar ratio of the organosilicon diol to the diisocyanate A is 1:2, and the molar ratio of the chain extender to the cross-linking agent is 20:1.

[0083] Example 6

[0084] The difference from Example 4 is that a crosslinking agent (trimethylolpropane) is added, and the molar number of hydroxyl groups of the chain extender in Example 4 is the same as the molar number of hydroxyl groups of the chain extender and the crosslinking agent in Example 6, and the rest is the same as Example 4, including the following raw material components in parts by weight:

[0085]

[0086]

[0087] The solvent DMF was added so that the raw material content of the polyurethane resin was 35 wt %; wherein the molar ratio of the organosilicon diol to the diisocyanate A was 1:2, and the molar ratio of the chain extender to the cross-linking agent was 19:1.

[0088] Example 7

[0089] The difference from Example 5 is that the cross-linking agent is replaced with trimethylolpropane in an equal molar amount.

[0090] Example 8

[0091] The difference from Example 5 is that the cross-linking agent is replaced with 1,2,8-octantriol in an equal molar amount.

[0092] Example 9

[0093] The difference from Example 5 is that the chain extender is replaced with 1,6-hexanediol in an equal molar amount.

[0094] Example 10

[0095] The difference from Example 5 is that the molar ratio of the chain extender to the cross-linking agent is 13:1.

[0096] Comparative Example 1

[0097] The difference from Example 1 is that 20% of the molar number of the organosilicon polyol is replaced by PTMEG (molecular weight 1000), and the weight parts of each raw material are:

[0098]

[0099] Adding solvent DMF makes the raw material content of polyurethane resin 35wt%;

[0100] Wherein, the molar ratio of the organosilicon diol to the diisocyanate A is 1:2.

[0101] Comparative Example 2

[0102] The difference from Example 1 is that the molar ratio of the organosilicon diol to the diisocyanate A is 1:0.8, and the weight parts of each raw material are:

[0103]

[0104] The solvent DMF was added so that the raw material content of the polyurethane resin was 35 wt %; wherein the molar ratio of the organosilicon diol to the diisocyanate A was 1:0.8.

[0105] The preparation methods of the polyurethane resins of Examples 1 to 11 and Comparative Examples 1 and 2 are as follows:

[0106] 1) According to the formula, the organosilicon diol and diisocyanate A are reacted in a solvent-free condition to prepare a blocked organosilicon diol, and an antioxidant is optionally added during the preparation process. The reaction temperature is 65° C. and the reaction time is 1 hour;

[0107] 2) adding a chain extender and an optional cross-linking agent to the above reaction system, controlling the reaction temperature to 65° C. and the reaction time to 0.5 hours;

[0108] 3) Adding a catalyst to the reaction system of step 2) and stirring, adding 40% of the total amount of DMF solvent and 30% of the total amount of diisocyanate B in sequence during the stirring process, reacting to increase viscosity, and controlling the reaction temperature to 75° C.;

[0109] 4) Adding the remaining diisocyanate B and the remaining solvent to the reaction system obtained in step (3) in batches, reacting until the viscosity of the reaction system reaches 12000 mPa·s / 25° C., optionally adding methanol until the viscosity of the system is stable, to obtain the polyurethane resin.

[0110] The preparation methods of the PU synthetic leather of Application Examples 1 to 11 and Comparative Application Examples 1 and 2 are as follows:

[0111] 1) 100 parts of the polyurethane resin prepared in Examples 1-11 and Comparative Examples 1-2, 80 parts of DMF solvent, 5 parts of carbon black (commonly available on the market, particle size 50-70 nm), and stirring at a speed of 1500 r / min to obtain a mixed material;

[0112] 2) Pour the above mixture evenly from left to right on the release paper, apply it evenly by scraping, and put it into a 130°C oven to dry to obtain PU synthetic leather;

[0113] The prepared mixed material and PU synthetic leather were subjected to performance tests, and the test methods were as follows:

[0114] (1) Dispersion of carbon black in the mixed material (represented by My), the obtained mixed material is tested for dispersion, specifically, with reference to DIN55979 standard, the linseed oil in the standard is replaced by the mixed material prepared in this example, and the specific test and calculation methods refer to DIN55979 standard. The larger the value of My, the better the blackness, that is, the better the dispersion, that is, the better the color development.

[0115] (2) Color development (visual observation): The obtained PU synthetic leathers were evaluated according to the following standards: Grade 5: no color difference, the darkest color, and very good color development; Grade 4: no obvious color difference, good color development; Grade 4: visible color difference, and average color development;

[0116] The test results are shown in Table 1.

[0117] Table 1

[0118]

[0119]

[0120] The polyurethane resin of the present invention is used to prepare PU synthetic leather, and the mixed solution thereof has normal fluidity and good color development. The color development can reach level 4 or above when observed with the naked eye, and the color development effect is good; My reaches above 60, indicating good color development, and the tensile strength of the synthetic leather reaches above 22MPa.

[0121] From the comparison between Example 4 and Example 1, it can be seen that when the molecular weight of the silicone diol is large, the mechanical properties of the PU synthetic leather decrease and the color development decreases slightly.

[0122] Comparison of Example 5 with Example 1 and comparison of Example 6 with Example 4 show that the addition of the cross-linking agent enhances the mechanical properties of the PU synthetic leather, but slightly reduces the color development.

[0123] Compared with Example 1, Example 5 and Example 7, it can be seen that the addition of a cross-linking agent can improve the mechanical properties of the synthetic leather. However, when the cross-linking agent is trimethylolethane, the mechanical properties of the synthetic leather are enhanced, but the color development is slightly reduced; when the cross-linking agent is trimethylolpropane, not only the mechanics are improved, but also the good color development is maintained.

[0124] Compared with Example 5, it can be seen that when the carbon number of the cross-linking agent is greater than 6, the mechanical properties and color development properties of the synthetic leather of Example 8 are enhanced.

[0125] Compared with Example 5, Example 10 shows that when the molar ratio of the small molecule chain extender to the cross-linking agent is low, the solution state of the mixed material in step (1) in the application example is abnormal in fluidity.

[0126] In Comparative Example 1, compared with Example 1, 20% of the molar number of the organosilicon polyol was replaced with PTMEG (molecular weight 1000), which reduced the organosilicon polyol as the soft segment, so that the color development of the PU synthetic leather was significantly reduced.

[0127] In Comparative Example 2, compared with Example 1, the molar ratio of the silicone diol to the diisocyanate A is 1:0.8, which reduces the color development of the PU synthetic leather and reduces the mechanical properties.

[0128] In summary, the overall color uniformity of the synthetic leather obtained in the embodiment of the present application is good, and the synthetic leather prepared in the embodiment of the present application is soft and elastic, with a dry and skin-friendly surface, a delicate and light touch, and is not greasy, and can be widely used in clothing, luggage, etc.

[0129] The applicant declares that the present invention uses the above embodiments to illustrate the polyurethane resin, polyurethane synthetic leather, preparation method and application of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments 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 polyurethane resin, characterized in that The polyurethane resin is prepared by reacting a hard segment component and a soft segment component; the raw materials of the hard segment component include diisocyanate and a small molecule chain extender, and the raw materials of the soft segment component are organic silicon diol.

2. The polyurethane resin according to claim 1, characterized in that The raw materials for preparing the polyurethane resin include, by weight percentage:

3. The polyurethane resin according to claim 2, characterized in that The molar ratio of the organosilicon diol to diisocyanate A is 1:1.1-2.5; Preferably, the organosilicon diol has the following structure: Wherein, R is selected from C1-C20 alkylene or substituted C1-C20 alkylene, the substituent in the substituted C1-C20 alkylene is C1-C10 alkyl or C6-C20 aryl, and n is an integer of 1 to 30.

4. The polyurethane resin according to any one of claims 1 to 3, characterized in that The molecular weight of the organosilicon diol is 1000-5000 g / mol, preferably 1000-3000 g / mol.

5. The polyurethane resin according to any one of claims 1 to 4, characterized in that The diisocyanate A and diisocyanate B are independently selected from one or a combination of at least two of 4,4'-diphenylmethane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane-4,4-diisocyanate 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate or polymethylene polyphenyl polyisocyanate; Preferably, the small molecule chain extender is one or a combination of at least two of ethylene glycol, 1,4-butanediol, 2-methyl-1,3-propanediol or neopentyl glycol.

6. The polyurethane resin according to any one of claims 1 to 5, characterized in that The raw materials for preparing the polyurethane resin also include a cross-linking agent; Preferably, the weight percentage content of the crosslinking agent in the raw materials for preparing the polyurethane resin is 0.3-1%; Preferably, the cross-linking agent is alkanetriol; Preferably, the alkanetriol is selected from any one or a combination of at least two of glycerol, trimethylolpropane, tri(hydroxymethyl)ethane, 1,2,4-butanetriol, 1,2,5-pentanetriol, 1,2,6-hexanetriol, 1,2,7-heptanetriol, 1,2,8-octantriol, 1,2,9-nonanetriol, 1,2,10-decanetriol or 3,7,11,15-tetramethyl-1,2,3-hexanetriol; preferably any one or a combination of at least two of tri(hydroxymethyl)ethane, 1,2,4-butanetriol, 1,2,6-hexanetriol, 1,2,10-decanetriol or 3,7,11,15-tetramethyl-1,2,3-hexanetriol; Preferably, the alkanetriol is selected from alkanetriols having a carbon number ≥ 6; Preferably, the molar ratio of the small molecule chain extender to the cross-linking agent is (15-40):

1.

7. The polyurethane resin according to any one of claims 1 to 5, characterized in that The raw materials for preparing the polyurethane resin also include a catalyst; Preferably, the weight percentage content of the catalyst in the raw material for preparing the polyurethane resin is 0.001% to 0.01%; Preferably, the catalyst is an organic bismuth catalyst; Preferably, the raw materials for preparing the polyurethane resin also include a chain terminator; Preferably, the chain terminator is selected from any one or a combination of at least two of methanol, ethanol or isopropanol; Preferably, the weight percentage content of the chain terminator in the raw materials for preparing the polyurethane resin is 0.005% to 1%; Preferably, the raw materials for preparing the polyurethane resin also include an antioxidant; Preferably, the weight percentage content of the antioxidant in the raw material for preparing the polyurethane resin is 0.01% to 1%; Preferably, the antioxidant is selected from any one or a combination of at least two of a hindered phenol antioxidant or a phosphite antioxidant; Preferably, the raw materials for preparing the polyurethane resin also include a solvent, and the amount of the solvent is such that the mass percentage content of other raw materials for preparing the polyurethane resin in the solvent is 30 to 50%; Preferably, the solvent is selected from dimethylformamide and / or dimethylacetamide.

8. The method for preparing a polyurethane resin according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: (1) mixing the organosilicon diol with the diisocyanate A to react; (2) adding a small molecule chain extender to the reaction system obtained in step (1) to carry out a reaction; (3) adding part of the solvent to the reaction system obtained in step (2), and then adding part of the diisocyanate B to react; (4) Adding the remaining diisocyanate B and the remaining solvent to the reaction system obtained in step (3) in batches to react, and obtaining the polyurethane resin after the viscosity of the system stabilizes.

9. The preparation method according to claim 8, characterized in that: The mixed raw materials in step (1) also include an antioxidant; Preferably, the reaction in step (1) is a solvent-free reaction, the reaction temperature is 60-70° C., and the reaction time is 1-2 hours; Preferably, step (2) further comprises adding a cross-linking agent to the reaction system obtained in step (1); Preferably, the reaction temperature in step (2) is 60-70° C., and the reaction time is 0.5-2 hours; Preferably, the reaction temperature in step (3) is 70-80°C and the reaction time is 1-2 hours; Preferably, the partial solvent in step (3) is 20% to 50% of the total solvent; Preferably, the amount of the partial diisocyanate B in step (3) is 20% to 50% of the total amount of diisocyanate B; Preferably, the temperature for the reaction of adding diisocyanate B and solvent in batches in step (4) is 70-80°C; Preferably, the step (4) further comprises adding a catalyst to the reaction system obtained in step (3) before adding the remaining diisocyanate B and the remaining solvent in batches; Preferably, in the reaction in step (4), when the viscosity of the system increases to 8000-16000 mPa·s / 25°C, a chain terminator is optionally added and the reaction is continued, and the polyurethane resin is obtained after the viscosity of the system stabilizes; Preferably, the reactions in steps (1) to (4) are all carried out under stirring.

10. A polyurethane synthetic leather, characterized in that: The polyurethane synthetic leather is prepared using the polyurethane resin according to any one of claims 1 to 7.

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