Ultra-soft polyurethane resin with high hydrolysis resistance and preparation method thereof

Abstract

The invention relates to the technical field of polyurethane resin for synthetic leather, in particular to ultra-soft polyurethane resin with high hydrolysis resistance and a preparation method thereof. The invention discloses ultra-soft polyurethane resin with high hydrolysis resistance. The ultra-soft polyurethane resin comprises closed polyurethane resin and an amine curing agent, the blocked polyurethane resin is prepared from the following raw materials in percentage by mass: 10 to 20 weight percent of carbodiimide modified MDI (methylene diphenyl diisocyanate), 1 to 5 weight percent of chain extender, 5 to 15 weight percent of polycarbonate polyol, 40 to 60 weight percent of hydrolysis-resistant modified polyester polyol, 2 to 10 weight percent of sealing agent, 0.005 to 0.05 weight percent of bismuth neodecanoate and the balance of functional additive. The polyurethane interlayer resin prepared in the invention not only has good hydrolysis resistance and heat-resistant stability, but also has soft and comfortable hand feeling, and also has good low-temperature-resistant flexibility and bonding stability.

Description

Technical Field

[0001] The present application relates to the technical field of polyurethane resin for synthetic leather, and in particular to an ultra-soft polyurethane resin with high hydrolysis resistance and a preparation method thereof. Background Art

[0002] Polyurethane synthetic leather includes a base fabric layer, an adhesive layer, a polyurethane intermediate layer, and a polyurethane surface layer. The polyurethane intermediate layer improves the overall feel, flexibility, and thickening of the synthetic leather. Due to its thick layer, it has higher requirements for hydrolysis resistance and jungle aging performance. The polyester polyurethane intermediate layer has a high ester bond density and a good degree of microphase separation, which gives the polyurethane intermediate layer better overall mechanical properties. However, the ester bonds it contains still cause defects in its hydrolysis resistance. The polyether polyurethane intermediate layer performs well in hydrolysis resistance, low temperature performance, flexibility, and processing performance, but its mechanical properties are insufficient and cannot meet the mechanical performance requirements of polyurethane intermediate layer resins for automotive leather.

[0003] At present, the solvent-free intermediate layer polyurethane resin for automotive interior leather disclosed in CN06220817A in the existing patent technology is prepared by mixing component A and component B in a mass ratio of 2.5:~1:2.5; component A is prepared by the following components in mass parts: 5-15 parts of diisocyanate; 70-80 parts of oligomer diol; 1-10 parts of small molecule diol; 0.5-5 parts of small molecule triol; 0.01-0.5 parts of catalyst; 0.5-2.5 parts of light / heat stabilizer; 0.02-0.5 parts of leveling agent; 0.2-2.0 parts of solvent-free color paste; group B is prepared by the following components in mass parts: 40-50 parts of diisocyanate; 0-10 parts of triisocyanate; 35-50 parts of polytetrahydrofuran diol; 0.5-5 parts of small molecule diol; 0-2 parts of small molecule triol; 0.5-1.0 parts of antioxidant. The strategy for modifying the hydrolysis resistance of the middle layer polyurethane resin is to use trifunctional small molecule triols and triisocyanates to improve the overall crosslinking density of the molecular chain finally formed, and combine the contained polytetramethylene glycol as a soft segment block, thereby giving the polyurethane middle layer good hydrolysis resistance and mechanical strength. However, the inventors found that this scheme has the following defects: the overall crosslinking density of the molecular chain of the polyurethane middle layer prepared by it is relatively high, and the polyurethane middle layer plays a thickening role, resulting in the overall hardness of the polyurethane synthetic leather being relatively high, and the flexibility and feel are relatively poor, which limits its scope of use. Summary of the invention

[0004] In order to solve the problems of high hardness, poor flexibility and relatively poor hand feel of the polyurethane middle layer in the above-mentioned prior art, the present invention provides an ultra-soft polyurethane resin with high hydrolysis resistance and a preparation method thereof.

[0005] The present application provides an ultra-soft polyurethane resin with high hydrolysis resistance, which is achieved through the following technical solutions: A super-soft polyurethane resin with high hydrolysis resistance comprises a blocked polyurethane resin and an amine curing agent, wherein the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:(5-10); the amine curing agent is composed of at least one of 1,11-diamino-3,6,9-trioxaundecane and 4,4'-diaminodicyclohexylmethane, 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine, and 2,2'-diaminoethylene glycol diphenyl ether; the blocked polyurethane resin is made of the following raw materials in mass percentage: 10-20wt% of carbodiimide modified MDI, 1-5wt% of a chain extender, 5-15wt% of a polycarbonate polyol, 50-75wt% of a hydrolysis-resistant modified polyester polyol, 2-10wt% of a blocking agent, 0.005-0.05wt% of bismuth neodecanoate, and the remainder is a functional additive.

[0006] Preferably, the blocking agent is a mixture of 3,5-dimethylpyrazole and at least one of 3'-(trifluoromethyl)acetophenone oxime, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, 1-(thiophen-2-yl)ethanone oxime, 1-(4-pyridine)-1-ethanone oxime and methyl ethyl ketone oxime.

[0007] The polyurethane intermediate layer resin prepared by compounding carbodiimide modified MDI, polycarbonate polyol, hydrolysis-resistant modified polyester polyol and sealing agent in a specific proportion in the present invention not only has good hydrolysis resistance and heat stability, but also has a soft and comfortable hand feel, and has good low-temperature flexibility and bonding stability, thereby expanding the application range of the synthetic leather prepared by using the resin.

[0008] Preferably, the blocking agent is a mixture of 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime and methyl ethyl ketone oxime; the 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime and methyl ethyl ketone oxime are mixed in a mass ratio of (20-25):(5-10):(65-75) to form the blocking agent.

[0009] The use of the compounded sealant can improve the hydrolysis resistance, weather resistance and heat stability of the middle layer of synthetic leather, and also provide good soft and comfortable hand feel, effectively solving the problem of hardening and poor hand feel of synthetic leather.

[0010] Preferably, the polycarbonate polyol is a polycarbonate diol with a number average molecular weight of 1000-2000, and the polycarbonate diol is at least one of CD210PL polycarbonate diol and CD220PL polycarbonate diol of Daicel of Japan, T6001 polycarbonate diol and T6002 polycarbonate diol of Asahi Kasei Chemicals of Japan.

[0011] The use of the above-mentioned preferred polycarbonate diol can improve the hydrolysis resistance and weather resistance of the prepared synthetic leather middle layer, and at the same time give the synthetic leather as a whole relatively good mechanical properties. It should be noted that the ultraviolet resistance of carbonate diol is relatively poor, the production pollution is relatively large, and the cost is relatively high. Therefore, it is necessary to regulate the addition amount of carbonate diol in the formula to produce and prepare synthetic leather with good economy and excellent hydrolysis resistance, so as to facilitate the synthetic leather products prepared by the above-mentioned middle layer polyurethane resin to be launched on the market.

[0012] Preferably, the amine curing agent is 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine; the mass ratio of the 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine is (8-9):(1-2).

[0013] In the present invention, the crosslinking density of the polyurethane is adjusted to give it good softness and at the same time the fluorine content is regulated to ensure the bonding strength between the polyurethane and the surface layer and the base fabric and improve the hydrolysis resistance.

[0014] Preferably, the hydrolysis-resistant modified polyester polyol comprises C6-C12 diacid, C3-C6 diol, and dihydroxy-terminated polysiloxane oligomer in a molar ratio of 2:(1.8-2.0):(0.05-0.3), and the total molar amount of hydroxyl groups in the C3-C6 diol and the dihydroxy-terminated polysiloxane oligomer is greater than the molar amount of carboxyl groups in the C6-C12 diacid.

[0015] Preferably, the C6-C12 diacid is at least one of sebacic acid, adipic acid, azelaic acid, and pimelic acid; the C3-C6 diol is 3-fluoro-1,2-propanediol combined with at least one of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and hexanediol.

[0016] Preferably, the molar amount of the 3-fluoro-1,2-propylene glycol is 0.04-0.12 times the molar amount of the C3-C6 diol; the dihydroxy-terminated polysiloxane oligomer is prepared by hydrolyzing dimethoxysilane, condensing silanol, extracting toluene, and removing toluene by vacuum distillation.

[0017] Preferably, the C6-C12 diacid is sebacic acid; the C3-C6 diol is 3-fluoro-1,2-propanediol, hexanediol, and 3-methyl-1,5-pentanediol in a molar ratio of (6-8):(60-80):(12-34); and the dimethoxysilane is dimethoxymethylpropylsilane.

[0018] Preferably, the hydrolysis-resistant modified polyester polyol comprises sebacic acid, 3-fluoro-1,2-propylene glycol, hexanediol, 3-methyl-1,5-pentanediol, and dihydroxy-terminated polysiloxane oligomer in a molar ratio of 2:(0.10-0.15):(1.40-1.50):(0.40-0.50):0.1.

[0019] The hydrolysis-resistant modified polyester polyol prepared by adopting the above technical scheme has good hydrolysis resistance and good soft segment molecular chain flexibility, which gives the synthetic leather prepared therefrom good hydrolysis resistance and softness.

[0020] Preferably, the preparation method of the hydrolysis-resistant modified polyester polyol is as follows: Step 1, preparation of a dihydroxy-terminated polysiloxane oligomer: first, dimethoxysilane is subjected to a hydrolysis reaction with water at a pH value of 3-4 and a temperature of 55-60° C. for 15-40 minutes, and after the hydrolysis reaction is completed, dibutyltin dilaurate and toluene are added, wherein the mass of the dibutyltin dilaurate is 100-500ppm of the mass of the dimethoxysilane, and the mass of the toluene is 4-12 times the mass of the dimethoxysilane, and a silanol condensation reaction is carried out at 60-80° C. for 30-60 minutes, and extraction and washing are carried out with deionized water for at least three times, and the obtained extract is subjected to reduced pressure distillation to remove toluene to obtain a dihydroxy-terminated polysiloxane oligomer; Step 2: Add sebacic acid, 3-fluoro-1,2-propylene glycol, and dihydroxy-terminated polysiloxane oligomer into a reaction kettle, then add tetraisopropyl titanate and mix evenly, wherein the tetraisopropyl titanate is 300-500ppm of the mass of sebacic acid, heat to 130-135°C and react until water is discharged, add hexylene glycol and 3-methyl-1,5-pentanediol and stir evenly, then continue to react at 130-135°C for 15-30 minutes, heat to 230-235°C, and perform ester exchange reaction for 100-125 minutes; Step three, after the ester exchange reaction is completed, the acid value of the material is tested. If the acid value is >10 mg KOH / g, the ester exchange reaction is continued for 10 minutes and the acid value is tested again. The above operation is repeated until the acid value is <10 mg KOH / g, and then the vacuum is pumped to a gauge pressure from 0.018 MPa to 0.098 MPa. After continuing for 15 minutes, the hydroxyl value of the material is tested. When the detected hydroxyl value is 22-38 mg KOH / g, the temperature is lowered and the material is discharged to obtain a hydrolysis-resistant modified polyester polyol with a number average molecular weight of 3000-5000.

[0021] The preparation method of the hydrolysis-resistant modified polyester polyol provided by the present invention is relatively simple, and the requirements for synthesis equipment are relatively low. Conventional polyester diol synthesis equipment can be put into production, thereby facilitating its industrial mass production, reducing the production cost of the hydrolysis-resistant modified polyester polyol, and thus reducing the overall production cost of synthetic leather.

[0022] In the second aspect, the present application provides a method for preparing an ultra-soft polyurethane resin with high hydrolysis resistance, which is achieved by the following technical scheme: A method for preparing an ultra-soft polyurethane resin with high hydrolysis resistance comprises the following steps: Step 1, preparation of hydrolysis-resistant modified polyester polyol; Step 2, carbodiimide modified MDI, polycarbonate polyol, the hydrolysis-resistant modified polyester polyol prepared in step 1, and 15-30wt% of bismuth neodecanoate in total mass are mixed evenly, and reacted at 70-80° C. for 1-2 hours; Step 3, adding a chain extender and mixing evenly, reacting at 70-80° C. until the NCO mass content in the system reaches 0.5-5%, thereby obtaining a terminal isocyanate prepolymer; Step 4: Add the blocking agent and the remaining catalyst and mix them evenly, then perform a blocking reaction at 70-80° C. until the NCO mass content in the system is 0%, add a functional additive and stir for 15-30 minutes until the temperature drops to room temperature, and obtain a blocked polyurethane resin; Step 5: The blocked polyurethane resin and the amine curing agent are mixed evenly according to a proportion to obtain a hydrolysis-resistant polyurethane intermediate layer resin.

[0023] The preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance provided by the present invention can prepare a polyurethane intermediate layer with excellent hydrolysis resistance and heat stability and soft and comfortable hand feel, thereby giving the synthetic leather prepared by using the intermediate layer good hydrolysis resistance, heat stability and soft hand feel.

[0024] The preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance provided by the present invention is relatively simple, has low requirements on synthesis equipment and low difficulty in process synthesis operation, realizes industrial mass production, and reduces total production cost.

[0025] In summary, this application has the following advantages: 1. The polyurethane intermediate layer resin prepared in the present invention ensures the bonding stability with the surface layer and the base fabric, and has good softness, hydrolysis resistance, heat stability, low temperature resistance and flexibility, and UV resistance. The synthetic leather prepared by using the resin has a relatively wide range of applications.

[0026] 2. The preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance provided by the present invention can prepare a polyurethane intermediate layer with excellent hydrolysis resistance and heat stability, and the preparation method is relatively simple, the implementation operation is low, and it is easy to realize industrial mass production. DETAILED DESCRIPTION

[0027] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples and comparative examples. Example

[0028] A super-soft polyurethane resin with high hydrolysis resistance includes a blocked polyurethane resin and an amine curing agent, wherein the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:(5-10). The amine curing agent affects the crosslinking density of the polyurethane intermediate layer film, and its crosslinking density affects the mechanical properties, hardness, and hydrolysis resistance of the polyurethane intermediate layer film. Therefore, the amount of the amine curing agent added needs to be regulated in the formula of the super-soft polyurethane resin with high hydrolysis resistance. Preferably, the mass ratio of the blocked polyurethane resin to the amine curing agent is preferably 100:(6.8-7.2).

[0029] The component composition of the amine curing agent also affects the comprehensive performance of the polyurethane intermediate layer film. The amine curing agent is composed of 1,11-diamino-3,6,9-trioxa-undecane and at least one of 4,4'-diaminodicyclohexylmethane, 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine, and 2,2'-diaminoethylene glycol diphenyl ether. The polyurethane intermediate layer film made using the above amine curing agent contains fluorine and heterocyclic structures, which improves the overall hydrolysis resistance and heat stability, and inevitably affects the bonding strength between the polyurethane intermediate layer and the base fabric and the surface layer. Therefore, it is necessary to regulate the content of each component in the amine curing agent. Specifically, the sealing agent is a mixture of 1,11-diamino-3,6,9-trioxa-undecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in a mass ratio of (8-9):(1-2).

[0030] The blocked polyurethane resin is prepared from the following raw materials in percentage by weight: 10-20 wt % of carbodiimide modified MDI, 1-5 wt % of a chain extender, 5-15 wt % of a polycarbonate polyol, 50-75 wt % of a hydrolysis-resistant modified polyester polyol, 2-10 wt % of a blocking agent, 0.005-0.05 wt % of bismuth neodecanoate, and the remainder being a functional additive.

[0031] The chain extender is at least one of 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol. Preferably, the chain extender is 1,6-hexanediol.

[0032] The polycarbonate polyol is a polycarbonate diol with a number average molecular weight of 1000 to 2000. Specifically, the polycarbonate diol is at least one of CD210PL polycarbonate diol and CD220PL polycarbonate diol produced by Daicel, T6001 polycarbonate diol and T6002 polycarbonate diol produced by Asahi Chemicals.

[0033] The blocking agent is a mixture of 3,5-dimethylpyrazole and at least one of 3'-(trifluoromethyl)acetophenone oxime, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, 1-(thiophene-2-yl)ethanone oxime, 1-(4-pyridine)-1-ethanone oxime, and methyl ethyl ketone oxime. The blocking agent in the blocked polyurethane resin affects the comprehensive performance of the polyurethane intermediate layer film, and it is necessary to regulate each component of the blocking agent. Specifically, the blocking agent is 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, and methyl ethyl ketone oxime in a mass ratio of (20-25):(65-75):(5-10) to form a blocking agent mixture.

[0034] Functional additives include but are not limited to defoamers, leveling agents, antioxidants, anti-ultraviolet agents, flame retardants, pigments, hydrolysis resistance agents, etc. Functional additives are added in combination according to the actual process synthesis needs.

[0035] Leveling agents can be selected from BYK's UV3510, UV3500, etc.

[0036] Defoamers can be selected from BYK's 060N, 066N, etc. The antioxidant can be a hindered amine antioxidant, such as 292, 622, 770, 994, etc.

[0037] The anti-ultraviolet agents include UV-320, UV-1130, UV-P, UV-1164, UV-234 and the like.

[0038] The flame retardant may be an inorganic flame retardant filler or a reactive organic flame retardant agent, wherein the inorganic flame retardant filler includes but is not limited to zinc borate, antimony dioxide, aluminum hydroxide, magnesium hydroxide, graphene, calcium carbonate, etc. The reactive organic flame retardant agent includes but is not limited to phosphorus-containing polyols, halogenated aromatic polyols, etc.

[0039] Hydrolysis resistance agents include but are not limited to HyMax@ 210, HyMax@ 213, HyMax® 220, etc.

[0040] The hydrolysis-resistant modified polyester polyol comprises C6-C12 diacid, C3-C6 diol and dihydroxyl-terminated polysiloxane oligomer in a molar ratio of 2:(1.8-2.0):(0.05-0.3), and the total molar amount of hydroxyl groups in C3-C6 diol and the dihydroxyl-terminated polysiloxane oligomer is greater than the molar amount of carboxyl groups in the C6-C12 diacid.

[0041] The C6-C12 diacid is at least one of sebacic acid, adipic acid, azelaic acid, and pimelic acid.

[0042] Preferably, the C6-C12 diacid is sebacic acid.

[0043] The C3-C6 diol is composed of 3-fluoro-1,2-propanediol and at least one of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol and hexanediol.

[0044] Preferably, C3-C6 diol is composed of 3-fluoro-1,2-propylene glycol, 3-methyl-1,5-pentanediol, and 1,6-hexanediol. The F element content in the soft segment of the molecular chain affects the bonding stability between the intermediate layer resin and the surface layer and the base fabric. The content of 3-fluoro-1,2-propylene glycol in C3-C6 diol needs to be regulated, and the molar amount of 3-fluoro-1,2-propylene glycol is 0.04-0.12 times the molar amount of C3-C6 diol. Preferably, the molar ratio of 3-fluoro-1,2-propylene glycol, hexanediol, and 3-methyl-1,5-pentanediol is (6-8):(60-80):(12-34).

[0045] The dihydroxy-terminated polysiloxane oligomer is prepared by hydrolyzing dimethoxysilane, condensing silanol, extracting toluene, and removing toluene by vacuum distillation. The dimethoxysilane is preferably dimethoxymethylpropylsilane.

[0046] Preferably, the hydrolysis-resistant modified polyester polyol synthesis raw materials are made of sebacic acid, 3-fluoro-1,2-propanediol, hexanediol, 3-methyl-1,5-pentanediol, and dihydroxy-terminated polysiloxane oligomer in a molar ratio of 2:(0.10-0.15):(1.40-1.50):(0.40-0.50):0.1.

[0047] A method for preparing an ultra-soft polyurethane resin with high hydrolysis resistance comprises the following steps: Step 1, preparation of hydrolysis-resistant modified polyester polyol; S1.1, preparation of dihydroxy-terminated polysiloxane oligomer: firstly, dimethoxysilane is subjected to a hydrolysis reaction with water at a pH value of 3-4 and a temperature of 55-60°C for 15-40 minutes, and after the hydrolysis reaction is completed, dibutyltin dilaurate and toluene are added, wherein the mass of dibutyltin dilaurate is 100-500ppm of the mass of the dimethoxysilane, and the mass of toluene is 4-12 times the mass of the dimethoxysilane, and a silanol condensation reaction is carried out at 60-80°C for 30-60 minutes, and the polysiloxane oligomer is extracted and washed with deionized water for at least three times, and the obtained extract is subjected to reduced pressure distillation to remove toluene to obtain a dihydroxy-terminated polysiloxane oligomer; S1.2, add sebacic acid, 3-fluoro-1,2-propylene glycol, and dihydroxy-terminated polysiloxane oligomer into a reaction kettle, then add tetraisopropyl titanate and mix evenly, the mass of tetraisopropyl titanate is 300-500ppm of sebacic acid, heat to 130-135°C and react until water is discharged, add hexylene glycol and 3-methyl-1,5-pentanediol and stir evenly, continue to react at 130-135°C for 15-30min, heat to 230-235°C, and transesterify for 100-125min; S1.3, after the completion of the transesterification reaction, the acid value of the material is tested. If the acid value is >10 mg KOH / g, the transesterification reaction is continued for 10 min and the acid value is tested again. The above operation is repeated until the acid value is <10 mg KOH / g, and then the vacuum is pumped to a gauge pressure from 0.018 MPa to 0.098 MPa. After 15 min, the hydroxyl value of the material is tested. When the detected hydroxyl value is 22-38 mg KOH / g, the temperature is lowered and the material is discharged to obtain a hydrolysis-resistant modified polyester polyol with a number average molecular weight of 3000-5000; Step 2, carbodiimide modified MDI, polycarbonate polyol, the hydrolysis-resistant modified polyester polyol prepared in step 1, and 15-30wt% of bismuth neodecanoate in total mass are mixed evenly, and reacted at 70-80° C. for 1-2 hours; Step 3, adding a chain extender and mixing evenly, reacting at 70-80° C. until the NCO mass content in the system reaches 0.5-5.0%, thereby obtaining a terminal isocyanate prepolymer; It should be noted that the NCO mass content in the terminal isocyanate prepolymer affects the blocking amount of the blocking agent, and the blocking agent affects the comprehensive performance of the polyurethane intermediate layer film. Therefore, it is necessary to specifically limit the NCO mass in the terminal isocyanate prepolymer. The NCO mass shall not be less than 0.5% and shall not be higher than 5.0%. On the premise that the blocking agent is a blocking agent mixture formed by uniformly mixing 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime and 1-(thiophene-2-yl)ethanone oxime in a mass ratio of (20-25):(5-10):(65-75), the NCO mass in the terminal isocyanate prepolymer is preferably 1.5-3.0%.

[0048] Step 4: Add the blocking agent and the remaining catalyst and mix them evenly, then perform a blocking reaction at 70-80° C. until the NCO mass content in the system is 0%, add a functional additive and stir for 15-30 minutes until the temperature drops to room temperature, and obtain a blocked polyurethane resin; Step 5: Mix the blocked polyurethane resin and the amine curing agent in a uniform ratio to obtain a hydrolysis-resistant polyurethane intermediate layer resin. The hydrolysis-resistant polyurethane intermediate layer resin is applied to the preparation of synthetic leather: The blocked polyurethane resin and the amine curing agent are mixed in a uniform ratio to obtain a hydrolysis-resistant polyurethane intermediate layer resin, which is then applied to the polyurethane surface layer and preheated at 120°C for 1-2 minutes for leveling and degassing, and then placed in an oven at 140-145°C for curing reaction for 3-5 minutes. After complete curing, directly apply the primer to the base fabric, dry it, and peel it off to obtain a hydrolysis-resistant synthetic leather product.

[0049] Example 1: An ultra-soft polyurethane resin with high hydrolysis resistance includes a blocked polyurethane resin and an amine curing agent, and the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:5.

[0050] The amine curing agent is composed of 1,11-diamino-3,6,9-trioxaundecane and 4,4'-diaminodicyclohexylmethane in a mass ratio of 1:1.

[0051] The blocked polyurethane resin is prepared from 375.4 g of carbodiimide modified MDI (Wanhua MDI100H), 400 g of CD220PL polycarbonate diol, 1800 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000, 29.54 g of 1,6-hexanediol, 22.11 g of 3,5-dimethylpyrazole, 85.38 g of methyl ethyl ketone oxime, 0.30 g of bismuth neodecanoate, 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234.

[0052] A method for preparing an ultra-soft polyurethane resin with high hydrolysis resistance comprises the following steps: Step 1, preparation of hydrolysis-resistant modified polyester polyol; S1.1, preparation of dihydroxy-terminated polysiloxane oligomer: firstly, dimethoxymethylpropylsilane (molecular weight is 148.276, CAS No. 18173-73-4) is subjected to hydrolysis reaction with water at pH 3 and temperature 60°C for 30 minutes, and after the hydrolysis reaction is completed, dibutyltin dilaurate (the mass of dibutyltin dilaurate is 400ppm of the mass of dimethoxysilane) and toluene (the mass of toluene is 10 times the mass of dimethoxysilane) are added, and silanol condensation reaction is carried out at 68°C for 60 minutes, and the extraction and washing are carried out three times with deionized water, and the obtained extract is subjected to reduced pressure distillation to remove the solvent toluene in the extract, and the dihydroxy-terminated polysiloxane oligomer can be obtained, and the hydroxyl value is measured to be 242.4 mgKOH / g, that is, the molecular weight is 461, and it is set aside; S1.2, put 2 mol of sebacic acid (404.5 g), 0.1 mol of 3-fluoro-1,2-propylene glycol (9.4 g), and 0.1 mol of the dihydroxy-terminated polysiloxane oligomer prepared in S1.1 (46.1 g) into a reactor, then add 0.2 g of tetraisopropyl titanate and mix evenly, heat to 135°C and react until water is discharged, add 1.5 mol of 1,6-hexanediol (177.26 g) and 0.40 mol of 3-methyl-1,5-pentanediol (47.27 g), stir evenly, and continue to react at 135°C for 30 min, then heat to 235°C and perform transesterification for 120 min; S1.3, after the completion of the transesterification reaction, the acid value of the material is tested. If the acid value is >10 mg KOH / g, the transesterification reaction is continued for 10 min and the acid value is tested again. The above operation is repeated until the acid value is <10 mg KOH / g, and then the vacuum is pumped to a gauge pressure from 0.018 MPa to 0.098 MPa. After 15 min, the hydroxyl value of the material is tested. When the detected hydroxyl value is 27.6 mg KOH / g, the temperature is lowered and the material is discharged to obtain a hydrolysis-resistant modified polyester polyol with an acid value of 0.45 mg KOH / g. The molecular weight of the obtained hydrolysis-resistant modified polyester polyol is 4000; Step 2: 375.4 g of carbodiimide modified MDI, 400 g of CD220PL polycarbonate diol, 1800 g of the hydrolysis-resistant modified polyester polyol with a molecular weight of 4000 prepared in step 1, and 0.09 g of bismuth neodecanoate were mixed evenly and reacted at 75° C. for 1 h; Step 3, add 29.54 g of 1,6-hexanediol and mix well, and react at 70° C. until the NCO mass content in the system reaches 2.5%, thereby obtaining a terminal isocyanate prepolymer; Step 4: add 22.11 g of 3,5-dimethylpyrazole, 85.38 g of methyl ethyl ketone oxime, and 0.21 g of bismuth neodecanoate and mix well, and then perform a capping reaction at 80° C. until the NCO mass content in the system is 0%, add 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234, and stir at 200 rpm for 30 min to cool to room temperature to obtain a blocked polyurethane resin; Step 5: The blocked polyurethane resin prepared in step 4 is uniformly mixed with 1,11-diamino-3,6,9-trioxaundecane and 4,4'-diaminodicyclohexylmethane at a mass ratio of 200:5:5 to obtain a hydrolysis-resistant polyurethane intermediate layer resin.

[0053] The difference between Example 2 and Example 1 is that the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:7.

[0054] The difference between Example 3 and Example 1 is that the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:10.

[0055] The difference between Example 4 and Example 1 is that the amine curing agent is composed of 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in a mass ratio of 9:1.

[0056] The difference between Example 5 and Example 1 is that the blocked polyurethane resin is made of 375.4 g of carbodiimide modified MDI, 400 g of CD220PL polycarbonate diol, 1800 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000, 29.54 g of 1,6-hexanediol, 24.03 g of 3,5-dimethylpyrazole, 79.28 g of methyl ethyl ketone oxime, 10.96 g of (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, 0.30 g of bismuth neodecanoate, 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234.

[0057] The difference in the preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance is: Step 4, add 24.03g of 3,5-dimethylpyrazole, 79.29g of methyl ethyl ketone oxime, 10.96g of (E)-1-(4-(trifluoromethoxy)phenyl) ketone oxime, and 0.21g of bismuth neodecanoate and mix them evenly, and then carry out a capping reaction at 80°C until the NCO mass content in the system is 0%, add 6.5g of BYK's UV3510, 2.2g of BYK's 060N, 2.5g of hindered amine antioxidant 622, and 2.5g of UV-234, stir at 200rpm for 30min to cool to room temperature, and obtain a closed polyurethane resin.

[0058] The difference between Example 6 and Example 1 is that the blocked polyurethane resin is made of 375.4 g of carbodiimide modified MDI, 400 g of CD220PL polycarbonate diol, 1800 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000, 29.54 g of 1,6-hexanediol, 24.03 g of 3,5-dimethylpyrazole, 79.29 g of methyl ethyl ketone oxime, 10.16 g of 3'-(trifluoromethyl) acetophenone oxime, 0.30 g of bismuth neodecanoate, 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234.

[0059] The difference in the preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance is: Step 4, add 24.03g of 3,5-dimethylpyrazole, 79.29g of methyl ethyl ketone oxime, 10.16g of 3'-(trifluoromethyl) acetophenone oxime, and 0.21g of bismuth neodecanoate and mix them evenly, and then carry out a capping reaction at 80°C until the NCO mass content in the system is 0%, add 6.5g of BYK's UV3510, 2.2g of BYK's 060N, 2.5g of hindered amine antioxidant 622, and 2.5g of UV-234, stir at 200rpm for 30min to cool to room temperature, and obtain a blocked polyurethane resin.

[0060] The difference between Example 7 and Example 1 is that the blocked polyurethane resin is made of 375.4 g of carbodiimide modified MDI, 400 g of CD220PL polycarbonate diol, 1800 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000, 29.54 g of 1,6-hexanediol, 24.03 g of 3,5-dimethylpyrazole, 60.96 g of methyl ethyl ketone oxime, 18.30 g of 1-(thiophene-2-yl) ethyl ketone oxime, 0.30 g of bismuth neodecanoate, 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234.

[0061] The difference in the preparation method of the ultra-soft polyurethane resin with high hydrolysis resistance is: Step 4, add 24.03g of 3,5-dimethylpyrazole, 60.96g of methyl ethyl ketone oxime, 18.30g of 1-(thiophen-2-yl) ethyl ketone oxime, and 0.21g of bismuth neodecanoate and mix them evenly, and then carry out a capping reaction at 80°C until the NCO mass content in the system is 0%, add 6.5g of BYK's UV3510, 2.2g of BYK's 060N, 2.5g of hindered amine antioxidant 622, and 2.5g of UV-234, stir at 200rpm for 30min to cool to room temperature, and obtain a closed polyurethane resin.

[0062] The difference between Example 8 and Example 1 is that the blocked polyurethane resin is made of 375.4 g of carbodiimide modified MDI (Wanhua MDI100H), 400 g of CD220PL polycarbonate diol, 1350 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 3000, 29.54 g of 1,6-hexanediol, 22.11 g of 3,5-dimethylpyrazole, 85.38 g of methyl ethyl ketone oxime, 0.25 g of bismuth neodecanoate, 5.43 g of BYK's UV3510, 1.84 g of BYK's 060N, 2.09 g of hindered amine antioxidant 622, and 2.09 g of UV-234.

[0063] The differences in the preparation methods of the homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 3000 and that of the homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000 are as follows: S1.3, after completing the ester exchange reaction, the acid value of the material is tested. If the acid value is >10mg KOH / g, the ester exchange reaction is continued for 10 minutes and the acid value is tested again. The above operation is repeated until the acid value is <10mg KOH / g, then the vacuum is pumped to a gauge pressure from 0.018MPa to 0.098MPa, and the hydroxyl value of the material is tested after 15 minutes. When the detected hydroxyl value is 36.9mgKOH / g, the temperature is lowered and the material is discharged to obtain a hydrolysis-resistant modified polyester polyol with an acid value of 0.5mg KOH / g. The target hydrolysis-resistant modified polyester polyol can be obtained.

[0064] The difference between Example 9 and Example 1 is that the blocked polyurethane resin is made of 375.4 g of carbodiimide modified MDI (Wanhua MDI100H), 400 g of CD220PL polycarbonate diol, 2250 g of homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 5000, 29.54 g of 1,6-hexanediol, 22.11 g of 3,5-dimethylpyrazole, 85.38 g of methyl ethyl ketone oxime, 0.35 g of bismuth neodecanoate, 7.57 g of BYK's UV3510, 2.56 g of BYK's 060N, 2.9 g of hindered amine antioxidant 622, and 2.9 g of UV-234.

[0065] The difference between the preparation methods of the homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 5000 and the homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000 is as follows: S1.3, after the ester exchange reaction is completed, the acid value of the material is tested. If the acid value is >10mg KOH / g, the ester exchange reaction is continued for 10min and the acid value is tested again. The above operation is repeated until the acid value is <10mg KOH / g, and then the vacuum is pumped to the gauge pressure from 0.018MPa to 0.098MPa, and the hydroxyl value of the material is tested after 15min. When the detected hydroxyl value is 22mgKOH / g, the temperature is lowered and the material is discharged to obtain the hydrolysis-resistant modified polyester polyol with an acid value of 0.44mg KOH / g, and the target hydrolysis-resistant modified polyester polyol can be obtained. .

[0066] The difference between Example 10 and Example 1 is that the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:7, and the amine curing agent is composed of 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in a mass ratio of 9:1.

[0067] The blocked polyurethane resin is prepared from 375.4 g of carbodiimide modified MDI, 400 g of CD220PL polycarbonate diol, 1800 g of a homemade hydrolysis-resistant modified polyester polyol with a molecular weight of 4000, 29.54 g of 1,6-hexanediol, 24.03 g of 3,5-dimethylpyrazole, 79.28 g of methyl ethyl ketone oxime, 10.96 g of (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, 0.30 g of bismuth neodecanoate, 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234.

[0068] The difference in the preparation method of super soft polyurethane resin with high hydrolysis resistance is: Step 4: Add 24.03 g of 3,5-dimethylpyrazole, 79.29 g of methyl ethyl ketone oxime, 10.96 g of (E)-1-(4-(trifluoromethoxy)phenyl) ethyl ketone oxime, and 0.21 g of bismuth neodecanoate, mix well, and perform end-capping reaction at 80 ° C until the NCO mass content in the system is 0%, add 6.5 g of BYK's UV3510, 2.2 g of BYK's 060N, 2.5 g of hindered amine antioxidant 622, and 2.5 g of UV-234, stir at 200 rpm for 30 min to cool to room temperature to obtain a blocked polyurethane resin.

[0069] Step 5: The blocked polyurethane resin prepared in step 4 is uniformly mixed with 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in a ratio of 1000:63:7 to obtain a hydrolysis-resistant polyurethane intermediate layer resin.

[0070] The difference between Example 11 and Example 10 is that: The difference in the preparation method of hydrolysis-resistant modified polyester polyol is that: S1.1 and S1.3 are the same; S1.2, put 2 mol of sebacic acid (404.5 g), 0.12 mol of 3-fluoro-1,2-propylene glycol (11.3 g), and 0.14 mol of the dihydroxy-terminated polysiloxane oligomer prepared in S1.1 (64.54 g) into the reactor, then add 0.2 g of tetraisopropyl titanate and mix evenly, raise the temperature to 135°C and react until water is discharged, add 1.4 mol of 1,6-hexanediol (165.44 g) and 0.44 mol of 3-methyl-1,5-pentanediol (52.0 g), stir evenly, and continue to react at 135°C for 30 min, then raise the temperature to 235°C and perform the ester exchange reaction for 120 min.

[0071] The difference between Example 12 and Example 10 is that: The difference in the preparation method of hydrolysis-resistant modified polyester polyol is that: S1.1 and S1.3 are the same; S1.2, put 2 mol of sebacic acid (404.5 g), 0.15 mol of 3-fluoro-1,2-propylene glycol (14.1 g), and 0.07 mol of the dihydroxy-terminated polysiloxane oligomer prepared in S1.1 (33.27 g) into the reactor, then add 0.2 g of tetraisopropyl titanate and mix evenly, raise the temperature to 135°C and react until water is discharged, add 1.38 mol of 1,6-hexanediol (163.07 g) and 0.5 mol of 3-methyl-1,5-pentanediol (59.1 g), stir evenly, and continue to react at 135°C for 30 min, then raise the temperature to 235°C and conduct ester exchange reaction for 120 min.

[0072] The difference between Comparative Example 1 and Example 1 is that the amine curing agent is 4,4'-diaminodicyclohexylmethane.

[0073] The difference between Comparative Example 2 and Example 1 is that the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:12.

[0074] The difference between Comparative Example 3 and Example 4 is that the amine curing agent is composed of 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in a mass ratio of 7:3.

[0075] The difference between Comparative Example 4 and Example 1 is that the blocked polyurethane resin is 375.4 g of carbodiimide modified MDI (Wanhua MDI100H), 400 g of CD220PL polycarbonate diol, 1350 g of polyester polyol with a molecular weight of 3000 (polyadipic acid / 1,4-butanediol ester diol produced by Zhejiang Hexin Technology Co., Ltd.), 29.54 g of 1,6-hexanediol, 22.11 g of 3,5-dimethylpyrazole, 85.38 g of methyl ethyl ketone oxime, 0.25 g of bismuth neodecanoate, 5.43 g of BYK's UV3510, 1.84 g of BYK's 060N, 2.09 g of hindered amine antioxidant 622, and 2.09 g of UV-234.

[0076] Preparation of synthetic leather: The prepared polyurethane intermediate layer resin was scraped onto HX-6120 (a hydrolysis-resistant polyurethane surface layer resin produced by Zhejiang Hexin Technology Co., Ltd.), preheated at 120°C for 80s, and reacted in an oven at 140°C for 5min to completely cure. Then, the primer HX-GD45 (a high-solid primer produced by Zhejiang Hexin Technology Co., Ltd.) was applied, and the base fabric was bonded, dried, and peeled off to obtain a synthetic leather test specimen.

[0077] 1. Peel strength is tested according to QB / T2888-2007 standard.

[0078] 2. Hydrolysis resistance test: After 10 weeks of jungle test in a constant temperature and humidity chamber at 70°C and 95%RH, the peel strength is tested according to QB / T2888-2007 standard.

[0079] 3. Weather-resistant and light-resistant Jungle Test: After the test sample and the control sample are placed in an environment of 80℃ and 75% humidity for 400 hours, they are bent 100,000 times at 25℃ to observe whether they crack; at -15℃, they are bent 50,000 times to observe whether they crack.

[0080] 4. Mechanical strength test of resin film: The polyurethane middle layer resin is matured at 140℃ to form a sample film, and the elongation breaking rate test and breaking strength are tested according to GB / T 1040.3-2006. The testing instruments and equipment are: electronic tensile machine (speed: 0-500mm / min, maximum load: 500N / 5000N, accuracy: 1N), punching machine, standard cutter (rectangular), thickness meter: accuracy 0.001mm; tensile machine parameter requirements: 1. Tensile speed: 100mm / min; 2. Sample width: 20.0mm; 3. Starting distance of the fixture: 50.0mm. Operation steps of mechanical strength test: 1. Cut the required samples with a standard cutter, and each group of samples shall not be less than three. All samples shall be free of bubbles, cracks, pinholes, gaps, and smooth edges within the 50mm mark. 2. The thickness measurement is carried out according to GB / T1040.3-2006. The thickness value of the same sample is 0.03mm within the mark 50.0mm, and the deviation is less than 0.01mm, otherwise it will be invalid. 2. Enter the thickness value of the sample, then clamp the sample in the upper and lower clamps of the electronic tensile machine, confirm that the stretching speed is 100mm / min, select the test state as "film stretching", and turn on the tensile machine. 3. When the sample breaks, the tensile machine automatically resets. At this time, record the displayed 100% modulus, breaking strength, elongation at break and other related data. 4. Test results: At least take the average of two test results as the final result (when the 100% modulus value is greater than or equal to 9.0MPa, the deviation should be less than 2.0MPa; when the 100% modulus value is less than 9.0MPa, the deviation should be less than 1.0MPa. The average relative deviation of the breaking strength shall not exceed 10%, and the average relative deviation of the breaking elongation shall not exceed 25%, otherwise it will be discarded). Mechanical strength test related data: Tensile strength (MPa): maximum force (N) / cross-sectional area; Elongation at break: (length at break - original length) / original length 50mm; 100% elongation: force at 100% displacement / cross-sectional area.

[0081] 6. Light fastness test: Xenon lamp test is carried out in accordance with ISO 105-B06.

[0082] Table 1: Test parameter table of polyurethane intermediate layer resin prepared in Examples 1-12 and Comparative Examples 1-4

[0083] It can be seen from Example 1 and Comparative Example 1 and Table 1 that the polyurethane intermediate layer tree prepared by using the compound amine curing agent has better comprehensive performance.

[0084] It can be seen from Examples 1-3 and Comparative Example 2 and Table 1 that the mass ratio of the blocked polyurethane resin to the amine curing agent is preferably 100:(5-10).

[0085] It can be seen from Example 4 and Comparative Example 3 and Table 1 that the mass ratio of 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine in the composite amine curing agent is preferably (8-9):(1-2), and too high a content of 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine affects the adhesion.

[0086] Combining Examples 5-7 with Example 1 and Table 1, it can be seen that the polyurethane intermediate layer tree prepared from a mixture of 3,5-dimethylpyrazole, methyl ethyl ketone oxime and (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime or 3'-(trifluoromethyl)acetophenone oxime or 1-(thiophen-2-yl)ethanone oxime has better overall performance.

[0087] It can be seen from Examples 8-12 and Comparative Example 4 and Table 1 that the polyurethane intermediate layer tree prepared by using the self-made hydrolysis-resistant modified polyester polyol of the present invention has better comprehensive performance.

[0088] In summary, the polyurethane intermediate layer resin prepared in the present invention ensures the bonding stability with the surface layer and the base fabric, and has good softness, heat resistance stability, low temperature resistance flexibility, UV resistance and excellent hydrolysis resistance. The peel strength of the polyurethane intermediate layer resin prepared in the present invention is ≥91.5% after being subjected to a jungle test in a constant temperature and humidity chamber at 70°C and 95%RH for 10 weeks. The synthetic leather prepared by the intermediate layer resin has a relatively wide range of applications.

[0089] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A super-soft polyurethane resin with high hydrolysis resistance, characterized in that: The invention comprises a blocked polyurethane resin and an amine curing agent, wherein the mass ratio of the blocked polyurethane resin to the amine curing agent is 100:(5-10); the amine curing agent is composed of at least one of 1,11-diamino-3,6,9-trioxaundecane and 4,4'-diaminodicyclohexylmethane, 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine, and 2,2'-diaminoethylene glycol diphenyl ether; The blocked polyurethane resin is prepared from the following raw materials in percentage by mass: 10-20 wt % of carbodiimide modified MDI, 1-5 wt % of a chain extender, 5-15 wt % of a polycarbonate polyol, 50-75 wt % of a hydrolysis-resistant modified polyester polyol, 2-10 wt % of a blocking agent, 0.005-0.05 wt % of bismuth neodecanoate, and the remainder being a functional additive.

2. The super-soft polyurethane resin with high hydrolysis resistance according to claim 1, characterized in that: The blocking agent is a mixture of 3,5-dimethylpyrazole and at least one of 3'-(trifluoromethyl)acetophenone oxime, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, 1-(thiophen-2-yl)ethanone oxime, 1-(4-pyridine)-1-ethanone oxime and methyl ethyl ketone oxime.

3. The super-soft polyurethane resin with high hydrolysis resistance according to claim 2, characterized in that: The blocking agent is a mixture of 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, and methyl ethyl ketone oxime; the 3,5-dimethylpyrazole, (E)-1-(4-(trifluoromethoxy)phenyl)ethanone oxime, and methyl ethyl ketone oxime are mixed in a mass ratio of (20-25):(5-10):(65-75) to form the blocking agent.

4. The super-soft polyurethane resin with high hydrolysis resistance according to claim 1, characterized in that: The polycarbonate polyol is a polycarbonate diol with a number average molecular weight of 1000-2000, and the polycarbonate diol is at least one of CD210PL polycarbonate diol and CD220PL polycarbonate diol produced by Daicel of Japan, and T6001 polycarbonate diol and T6002 polycarbonate diol produced by Asahi Chemical of Japan.

5. The super-soft polyurethane resin with high hydrolysis resistance according to claim 1, characterized in that: The amine curing agent is 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine; the mass ratio of 1,11-diamino-3,6,9-trioxaundecane and 2,6-diamino-3-fluoro-4-(trifluoromethyl)pyridine is (8-9):(1-2).

6. The super-soft polyurethane resin with high hydrolysis resistance according to claim 5, characterized in that: The hydrolysis-resistant modified polyester polyol comprises C6-C12 diacid, C3-C6 diol, and dihydroxyl-terminated polysiloxane oligomer in a molar ratio of 2:(1.8-2.0):(0.05-0.3), and the total molar amount of hydroxyl groups in the C3-C6 diol and the dihydroxyl-terminated polysiloxane oligomer is greater than the molar amount of carboxyl groups in the C6-C12 diacid; the C6-C12 diacid is at least one of sebacic acid, adipic acid, azelaic acid, and pimelic acid; the C3-C6 diol is -C6 diol is composed of 3-fluoro-1,2-propanediol and at least one of 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, and hexanediol; the molar amount of the 3-fluoro-1,2-propanediol is 0.04-0.12 times the molar amount of the C3-C6 diol; the dihydroxy-terminated polysiloxane oligomer is prepared by hydrolyzing dimethoxysilane, condensing silanol, extracting toluene, and removing toluene by reduced pressure distillation.

7. The super-soft polyurethane resin with high hydrolysis resistance according to claim 6, characterized in that: The C6-C12 diacid is sebacic acid; the C3-C6 diol is 3-fluoro-1,2-propylene glycol, hexanediol, and 3-methyl-1,5-pentanediol in a molar ratio of (6-8):(60-80):(12-34); and the dimethoxysilane is dimethoxymethylpropylsilane.

8. The super-soft polyurethane resin with high hydrolysis resistance according to claim 7, characterized in that: The hydrolysis-resistant modified polyester polyol comprises sebacic acid, 3-fluoro-1,2-propylene glycol, hexanediol, 3-methyl-1,5-pentanediol, and dihydroxy-terminated polysiloxane oligomer in a molar ratio of 2:(0.10-0.15):(1.40-1.50):(0.40-0.50):0.

1.

9. The super-soft polyurethane resin with high hydrolysis resistance according to claim 7, characterized in that: The preparation method of the hydrolysis-resistant modified polyester polyol is as follows: Step 1, preparation of a dihydroxy-terminated polysiloxane oligomer: first, dimethoxysilane is subjected to a hydrolysis reaction with water at a pH value of 3-4 and a temperature of 55-60° C. for 15-40 minutes, and after the hydrolysis reaction is completed, dibutyltin dilaurate and toluene are added, wherein the mass of the dibutyltin dilaurate is 100-500ppm of the mass of the dimethoxysilane, and the mass of the toluene is 4-12 times the mass of the dimethoxysilane, and a silanol condensation reaction is carried out at 60-80° C. for 30-60 minutes, and extraction and washing are carried out with deionized water for at least three times, and the obtained extract is subjected to reduced pressure distillation to remove toluene to obtain a dihydroxy-terminated polysiloxane oligomer; Step 2: Add sebacic acid, 3-fluoro-1,2-propylene glycol, and dihydroxy-terminated polysiloxane oligomer into a reaction kettle, then add tetraisopropyl titanate and mix evenly, wherein the tetraisopropyl titanate is 300-500ppm of the mass of sebacic acid, heat to 130-135°C and react until water is discharged, add hexylene glycol and 3-methyl-1,5-pentanediol and stir evenly, then continue to react at 130-135°C for 15-30 minutes, heat to 230-235°C, and perform ester exchange reaction for 100-125 minutes; Step three, after the ester exchange reaction is completed, the acid value of the material is tested. If the acid value is >10 mg KOH / g, the ester exchange reaction is continued for 10 minutes and the acid value is tested again. The above operation is repeated until the acid value is <10 mg KOH / g, and then the vacuum is pumped to a gauge pressure from 0.018 MPa to 0.098 MPa. After continuing for 15 minutes, the hydroxyl value of the material is tested. When the detected hydroxyl value is 22-38 mgKOH / g, the temperature is lowered and the material is discharged to obtain a hydrolysis-resistant modified polyester polyol with a number average molecular weight of 3000-5000.

10. A method for preparing a super-soft polyurethane resin with high hydrolysis resistance according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step 1, preparation of hydrolysis-resistant modified polyester polyol; Step 2, carbodiimide modified MDI, polycarbonate polyol, the hydrolysis-resistant modified polyester polyol prepared in step 1, and 15-30wt% of bismuth neodecanoate in total mass are mixed evenly, and reacted at 70-80° C. for 1-2 hours; Step 3, adding a chain extender and mixing evenly, reacting at 70-80° C. until the NCO mass content in the system reaches 0.5-5%, thereby obtaining a terminal isocyanate prepolymer; Step 4: Add the blocking agent and the remaining catalyst and mix them evenly, then perform a blocking reaction at 70-80° C. until the NCO mass content in the system is 0%, add a functional additive and stir for 15-30 minutes until the temperature drops to room temperature, and obtain a blocked polyurethane resin; Step 5: The blocked polyurethane resin and the amine curing agent are mixed evenly according to a proportion to obtain a hydrolysis-resistant polyurethane intermediate layer resin.

Images