A polyurethane prepolymer composition and its preparation method and application

Abstract

The present invention provides a polyurethane prepolymer composition and a preparation method and application thereof, wherein the polyurethane prepolymer composition is aliphatic isocyanate-terminated, obtained by reacting aliphatic isocyanate with polyol, and the mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is ≥50%; the polyurethane prepolymer composition comprises a combination of a first prepolymer and a second prepolymer, the first prepolymer is an adduct formed by the aliphatic isocyanate and the polyol in a molar ratio of 2:1, and the second prepolymer is an adduct formed by the aliphatic isocyanate and the polyol in a molar ratio of (n+1):n, n≥2; the mass percentage of the second prepolymer in the polyurethane prepolymer composition is 15-75%. The polyurethane prepolymer composition has both high molecular weight and low viscosity, excellent construction performance, and significantly improves the physical properties of the polyurethane product prepared by the polyurethane prepolymer composition.

Description

Technical Field

[0001] The invention belongs to the technical field of polyurethane materials, and in particular relates to a polyurethane prepolymer composition and a preparation method and application thereof. Background Art

[0002] Polyurethane is a type of polymer containing repeating units of carbamate in its molecular chain. It has many advantages such as excellent elasticity, good toughness, high hardness, wear resistance, solvent resistance, corrosion resistance, high and low temperature resistance, etc. It is widely used in many industries such as building materials, furniture, coatings, plastics, leather and adhesives. The raw materials for the preparation of polyurethane products usually include two components, one of which is a polyhydroxy compound, such as a small molecule polyol, or a polyhydroxy resin composed of alkyd resin, polyester resin, hydroxy acrylic resin, etc.; the other is a polyurethane prepolymer, which is formed by the preliminary polymerization of isocyanate monomers and polyols; in the processing of polyurethane, the polyurethane prepolymer undergoes a deep polymerization reaction with the polyol to form various polyurethane products with a large molecular weight.

[0003] As the main raw material for the preparation of polyurethane products, the components and quality of polyurethane prepolymers directly affect the processing and final performance of the products. Therefore, in order to obtain ideal polyurethane products, it is of great significance to study and optimize polyurethane prepolymers. For example, CN102659997A discloses a method for preparing a polyurethane prepolymer with low free isocyanate monomers, and the specific steps are as follows: first, vacuum dehydration of a triol and a diol to form a mixed alcohol; isocyanate monomers and ester solvents are placed in a reaction vessel to maintain a temperature of 30-70°C, and the mixed alcohol is dripped into it; after the dropwise addition is completed, the reaction is carried out at 40-70°C for 3-6h, and the material is cooled and discharged to obtain a polyurethane prepolymer; the obtained polyurethane prepolymer is separated, and the separated heavy components are used to adjust the solid content of the polyurethane prepolymer and the content of free isocyanate monomers with a dilution solvent. CN103396526A discloses a method for producing a yellowing-resistant polyurethane prepolymer, which comprises the following steps: firstly, adding polyether polyol, castor oil polyol and liquid copolyester polyol into a reaction kettle, heating and stirring for 2-3 hours, adding aliphatic isocyanate thereto, keeping the reaction at 80°C for 2.5 hours, then adding an organic tin catalyst, continuing the reaction for 1 hour, cooling the material, discharging the material and sealing and storing the material. CN102643407A discloses a method for preparing an isophorone diisocyanate prepolymer, which comprises the following steps: reacting isophorone diisocyanate (IPDI) and polyether polyol in the presence of a catalyst for 1-4 hours to obtain an IPDI prepolymer; gradually dripping trimethylolpropane after solvent azeotropic dehydration into the IPDI prepolymer, adding a trimerization catalyst after the dripping is completed, and adding an inhibitor when the theoretical NCO content is reached. CN109535385A discloses a polyurethane prepolymer, the preparation raw materials of which include: 55-90 parts of polyether polyol, 10-25 parts of polyisocyanate, and 2-6 parts of aliphatic or alicyclic diisocyanate. The introduction of aliphatic or alicyclic diisocyanate makes the prepolymer and the obtained polyurethane / polyurea surface layer have better yellowing resistance.

[0004] In general, the current research on polyurethane prepolymers is focused on two directions. The first is to reduce free monomers. Since polyurethane prepolymers use isocyanate monomers as raw materials, it is inevitable that a certain amount of isocyanate monomers will remain in the prepolymers. The residual isocyanate monomers not only bring potential health hazards and safety issues, but also affect the stability of the prepolymers, the open time during use, and the adhesion properties of polyurethane products. Therefore, it is necessary to reduce the content of free isocyanates in the prepolymers. The second is to improve the various physical properties of the prepolymers. For example, the use of aliphatic isocyanates to prepare prepolymers can improve the material's yellowing resistance and aging resistance; the use of aromatic isocyanates to prepare prepolymers can improve the material's strength and other mechanical properties. In recent years, people have had higher requirements on the performance and processing of polyurethane products, and polyurethane prepolymers have also faced new challenges: low molecular weight polyurethane prepolymers have low viscosity and are easy to construct, but it is difficult to prepare polyurethane products with excellent performance and suitable curing time; high molecular weight polyurethane prepolymers are suitable for the preparation of high-performance polyurethane products, but they have high viscosity and are difficult to construct; the addition of solvents can reduce viscosity and facilitate construction, but it brings higher VOC, and the subsequent solvent removal step also greatly prolongs the processing time.

[0005] Therefore, developing a polyurethane prepolymer with excellent performance, low viscosity and easy construction is a problem to be solved urgently in this field. Summary of the invention

[0006] In view of the deficiencies in the prior art, the object of the present invention is to provide a polyurethane prepolymer composition and a preparation method and application thereof. By designing aliphatic isocyanate and the formed prepolymer, the polyurethane prepolymer composition has both high molecular weight and low viscosity, excellent construction properties, and significantly improves the physical properties of the polyurethane products prepared therefrom.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polyurethane prepolymer composition, which is terminated with aliphatic isocyanate and obtained by reacting aliphatic isocyanate with polyol, wherein the mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is ≥50%; the polyurethane prepolymer composition comprises a combination of a first prepolymer and a second prepolymer, wherein the first prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of 2:1, and the second prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of (n+1):n, wherein n is ≥2; and the mass percentage of the second prepolymer in the polyurethane prepolymer composition is 15-75%.

[0009] In the present invention, the aliphatic isocyanate includes ≥50% of 1,5-pentamethylene diisocyanate (PDI), which reacts with a polyol to form a prepolymer, which can effectively reduce the symmetry and crystallinity of the prepolymer molecular structure, so that the polyurethane prepolymer composition has a large molecular weight while significantly reducing the viscosity, and has good fluidity and excellent workability.

[0010] The polyurethane prepolymer composition comprises a combination of a first prepolymer and a second prepolymer, wherein the first prepolymer is an adduct formed by aliphatic isocyanate and polyol in a molar ratio of 2:1, which can be abbreviated as "ABA structure" (also known as "chain number 1"), wherein A represents isocyanate and B represents polyol; the first prepolymer is a prepolymer with a lower molecular weight.

[0011] The second prepolymer is an adduct formed by aliphatic isocyanate and polyol in a molar ratio of (n+1):n, n≥2, and can be 3, 4, 5, etc. When n is 2, the corresponding prepolymer is abbreviated as "ABABA structure" (also known as "chain number is 2"); when n is 3, the corresponding prepolymer is abbreviated as "ABABABA structure" (also known as "chain number is 3"); and so on. The second prepolymer is a prepolymer with a chain number ≥2, which has a higher molecular weight.

[0012] The present invention uses a special design of aliphatic isocyanate to make the prepolymer formed by its reaction with polyol have significantly reduced viscosity, thereby solving the problem in the prior art that when other isocyanates are used, increasing the content of prepolymers with a number of links ≥ 2 (such as ABABA structure, ABABABA structure, etc.) in the formula will cause the system viscosity to be too high and unable to flow at room temperature. The polyurethane prepolymer composition has a high content of the second prepolymer with a number of links ≥ 2 and a large molecular weight, and has low viscosity, good fluidity and excellent construction performance. It can also simplify the removal step of free aliphatic isocyanate monomers in the preparation process and shorten the removal time. It is surprisingly found that in a polyurethane prepolymer composition prepared with an aliphatic isocyanate containing 1,5-pentamethylene diisocyanate, the second prepolymer with a number of links ≥ 2 can greatly improve the microphase separation degree of polyurethane within a specific content range, thereby improving the physical crosslinking degree, and then greatly improving the product performance. The polyurethane prepolymer composition is used to prepare polyurethane products, which can effectively improve the physical and mechanical properties of polyurethane products, especially significantly enhance the low-temperature flexibility of polyurethane products.

[0013] In the polyurethane prepolymer composition of the present invention, the mass percentage of the second prepolymer is 15-75%, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the said range.

[0014] Preferably, the mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is 50-100%, for example, it can be 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 60-100% is further preferred.

[0015] In the present invention, the aliphatic isocyanate includes chain aliphatic isocyanate and may also include cyclic aliphatic (also known as alicyclic) isocyanate.

[0016] Preferably, the aliphatic isocyanate further includes any one or a combination of at least two of 1,6-hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), cyclohexane diisocyanate (CHDI), dicyclohexylmethane diisocyanate (HMDI), and cyclohexane dimethyl diisocyanate (H6XDI).

[0017] Preferably, the average functionality of the polyol is 2, and the polyol may be any polyol with an average functionality of 2 known in the art.

[0018] Preferably, the number average molecular weight of the polyol is 300-12000 g / mol, for example, it can be 400 g / mol, 500 g / mol, 700 g / mol, 900 g / mol, 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2200 g / mol, 2500 g / mol, 2800 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 7000 g / mol, 9000 g / mol, 10000 g / mol or 11000 g / mol, and specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range, and 300-3000 g / mol is further preferred.

[0019] Preferably, the polyol includes any one or a combination of at least two of polyester polyol, polycaprolactone polyol, polycarbonate polyol, polyethylene oxide polyol, polypropylene oxide polyol, ethylene oxide-propylene oxide copolymer polyol, polytetramethylene oxide polyol, polypropylene glycol ether polyol, and vegetable oil polyol.

[0020] Exemplarily, the polyester polyol is prepared by dicarboxylic acid (preferably aliphatic dicarboxylic acid) and / or anhydride and excess diol; the polycaprolactone polyol is prepared by using ε-caprolactone and a polyol compound with an average functionality of 2 as initiators; the polyoxyethylene polyol is prepared by using ethylene oxide and a polyol compound with an average functionality of 2; the polyoxypropylene polyol is prepared by using propylene oxide and a polyol compound with an average functionality of 2; the oxyethylene-oxypropylene copolymer polyol is prepared by using ethylene oxide, propylene oxide and a polyol compound with an average functionality of 2.

[0021] Preferably, the molar ratio of the aliphatic isocyanate to the polyol is (2.2-15):1, for example, it can be 2.3:1, 2.5:1, 2.8:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, etc.

[0022] Preferably, the mass percentage of free aliphatic isocyanate monomer in the polyurethane prepolymer composition is ≤5%, for example, it can be 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and it is further preferably ≤0.5%, and more preferably ≤0.3%.

[0023] Preferably, the mass percentage of NCO groups in the polyurethane prepolymer composition is 2.5-15%, for example, it can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0024] Preferably, the mass percentage of the first prepolymer in the polyurethane prepolymer composition is 20-80%, for example, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 20-60% is further preferred.

[0025] Preferably, the second prepolymer comprises a combination of a third prepolymer and a fourth prepolymer.

[0026] The third prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of 3:2, which is abbreviated as ABABA structure, also known as "chain number 2".

[0027] The fourth prepolymer is a prepolymer of the aliphatic isocyanate and the polyol in a molar ratio (n 1 +1):n 1 The adduct formed, the n 1 ≥3; for example, n 1 is 3, 4, 5, etc.; the number of chain links of the fourth prepolymer is greater than 2, which can also be understood as "the number of chain links ≥ 3".

[0028] The mass percentage of the third prepolymer in the polyurethane prepolymer composition is 12-60%, for example, it can be 15%, 18%, 20%, 22%, 25%, 28%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 52%, 55% or 58%, as well as specific values ​​between the above points. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific points included in the range, and 35-60% is further preferred, and 40-60% is further preferred.

[0029] Preferably, the mass percentage of the fourth prepolymer in the polyurethane prepolymer composition is 3-25%, for example, it can be 4%, 5%, 7%, 9%, 10%, 12%, 15%, 18%, 20%, 22% or 24%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0030] As a preferred technical solution of the present invention, the polyurethane prepolymer composition comprises a combination of a first prepolymer (the number of chain links is 1), a third prepolymer (the number of chain links is 2) and a fourth prepolymer (the number of chain links is greater than 2). By compounding prepolymers with different numbers of chain links / molecular weights, the polyurethane prepolymer composition has a specific higher molecular weight and molecular weight distribution, low viscosity, good fluidity at room temperature, and is easy to construct; and when used to prepare polyurethane products, based on its specific higher molecular weight and molecular weight distribution, it has a higher degree of microphase separation, greatly increases the degree of physical crosslinking, and gives the polyurethane products excellent physical and mechanical properties, especially excellent low-temperature flexibility.

[0031] Preferably, the viscosity of the polyurethane prepolymer composition at 25° C. is ≤20000 mPa·s, for example, it may be 1000 mPa·s, 2000 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 12000 mPa·s, 15000 mPa·s or 18000 mPa·s, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and it is further preferably ≤10000 mPa·s, and even more preferably ≤8000 mPa·s.

[0032] In a second aspect, the present invention provides a method for preparing the polyurethane prepolymer composition as described in the first aspect, the preparation method comprising: reacting an aliphatic isocyanate with a polyol to obtain the polyurethane prepolymer composition.

[0033] Preferably, the reaction is carried out in the presence or absence of a catalyst.

[0034] Preferably, the catalyst is a compound that promotes carbamate formation, including any one or a combination of at least two of tertiary amines, alcohol amine compounds, N,N',N"-tris(dialkylaminoalkyl)hexahydrotriazine, bis(dimethylaminoethyl) ether, metal salts, amidines, tetraalkylammonium hydroxides, alkali metal hydroxides, alkali metal alcoholates, and C10-C20 fatty acid alkali metal salts.

[0035] Exemplarily, the tertiary amine includes triethylamine, tributylamine, dimethylbenzylamine, diethylbenzylamine, pyridine, picoline, dicyclohexylmethylamine, dimethylcyclohexylamine, N,N,N',N'-tetramethyldiaminodiethyl ether, bis(dimethylaminopropyl)urea, N-methylmorpholine, N-ethylmorpholine, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,3-butanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, Any one of pentamethyldiethylenetriamine, N-methylpiperidine, N-dimethylaminoethylpiperidine, N,N'-dimethylpiperazine, N-methyl-N'-dimethylaminopiperazine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), 1,2-dimethylimidazole, 2-methylimidazole, N,N-dimethylimidazole-β-phenylethylamine, 1,4-diazabicyclo[2.2.2]octane, and bis(N,N-dimethylaminoethyl)adipate, or a combination of at least two thereof.

[0036] Exemplarily, the alcoholamine compound includes any one of triethanolamine, triisopropanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, dimethylaminoethanol, and 2-(N,N-dimethylaminoethoxy)ethanol, or a combination of at least two thereof.

[0037] Exemplarily, the N,N',N"-tris(dialkylaminoalkyl)hexahydrotriazine includes N,N',N"-tris(dimethylaminopropyl)-s-hexahydrotriazine.

[0038] Exemplarily, the metal salt includes a metal organic salt and / or a metal inorganic salt, wherein the metal includes any one of iron, lead, bismuth, zinc, and tin, and exemplarily includes but is not limited to: ferrous chloride (II), ferric chloride (III), bismuth (III) 2-ethylhexanoate, bismuth (III) octanoate, bismuth (III) neodecanoate, zinc chloride, zinc 2-ethylhexanoate, tin (II) octanoate, tin (II) ethylhexanoate, tin (II) palmitate, dibutyltin (IV) dilaurate, (DBTL), dibutyltin (IV) dichloride, lead octanoate, any one or a combination of at least two of them.

[0039] Illustratively, the amidine includes 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine.

[0040] Exemplarily, the tetraalkylammonium hydroxide includes tetramethylammonium hydroxide and / or tetraethylammonium hydroxide.

[0041] Illustratively, the alkali metal hydroxide includes sodium hydroxide and / or potassium hydroxide.

[0042] Illustratively, the alkali metal alkoxide includes any one of sodium methoxide, sodium ethoxide, potassium isopropoxide, and sodium isopropoxide, or a combination of at least two thereof.

[0043] Illustratively, the C10-C20 fatty acid alkali metal salt may be a long-chain fatty acid alkali metal salt of C11, C12, C13, C14, C15, C16, C17, C18, or C19, and may contain an optionally pendant OH group.

[0044] Preferably, based on the sum of the masses of the aliphatic isocyanate and the polyol as 100%, the mass of the catalyst is ≤5%, for example, it can be 0% (not added), 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range, and it is further preferably ≤1%.

[0045] Preferably, the catalyst is added before the start of the reaction or at any time during the reaction.

[0046] In the present invention, the reaction is carried out in the presence or absence of a solvent, preferably in the absence of a solvent.

[0047] Preferably, the solvent can be any suitable solvent that is inert to the reactive groups of the starting components, illustratively including but not limited to: ethyl acetate, butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, 1-methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, toluene, xylene, chlorobenzene, petroleum solvent, higher substituted aromatic solvent, propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, N-methylpyrrolidone, N-methylcaprolactam, any one of N,N-dimethylformamide or a combination of at least two thereof.

[0048] Preferably, the reaction temperature is 60-120°C, for example, it can be 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C or 115°C, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0049] Preferably, the reaction time is 2-10 h, for example, it can be 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h or 9.5 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range.

[0050] Preferably, the reaction is carried out in a protective atmosphere.

[0051] Preferably, the protective atmosphere includes any one of a nitrogen atmosphere, an argon atmosphere, and a helium atmosphere, or a combination of at least two of them.

[0052] Preferably, a reaction inhibitor is added when the reaction reaches the end point.

[0053] As a preferred technical solution of the present invention, during the reaction, the NCO content of the system is tested according to the method in the standard "GB / T33312-2016". When the NCO content reaches below the theoretical value, it means that the reaction has reached the end point. At this time, a reaction inhibitor is added to the system, which is a substance that inhibits the isocyanate group from further reacting with the isocyanate group, the carbamate group, etc. to produce a side reaction, so that the obtained polyurethane prepolymer composition remains stable.

[0054] Preferably, the reaction inhibitor comprises any one or a combination of at least two of inorganic acids, acyl chloride compounds, sulfonic acid compounds, sulfonic acid ester compounds, monoalkyl phosphates, dialkyl phosphates, and acidic compounds containing silyl groups, and acyl chloride compounds are more preferred.

[0055] Preferably, the inorganic acid includes any one of hydrochloric acid, phosphorous acid, phosphoric acid, or a combination of at least two thereof.

[0056] Preferably, the acyl chloride compound includes any one of acetyl chloride, benzoyl chloride, isophthaloyl chloride or a combination of at least two thereof, and benzoyl chloride is more preferred.

[0057] Preferably, the sulfonic acid compound includes any one of methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, and dodecylbenzenesulfonic acid, or a combination of at least two thereof.

[0058] Preferably, the sulfonate compound includes methyl p-toluenesulfonate and / or ethyl p-toluenesulfonate.

[0059] Preferably, the monoalkyl phosphate includes monotridecyl phosphate.

[0060] Preferably, the dialkyl phosphate includes any one of dibutyl phosphate, dioctyl phosphate, di(2-ethylhexyl) phosphate, or a combination of at least two thereof.

[0061] Preferably, the acidic compound containing a silyl group includes any one of trimethylsilyl methanesulfonate, trimethylsilyl trifluoromethanesulfonate, tri(trimethylsilyl) phosphate, and diethyl phosphate-trimethylsilyl ester, or a combination of at least two thereof.

[0062] Preferably, based on the sum of the masses of the aliphatic isocyanate and the polyol as 100%, the mass of the reaction inhibitor is 1-200ppm, for example, it can be 5ppm, 10ppm, 20ppm, 30ppm, 40ppm, 50ppm, 70ppm, 90ppm, 100ppm, 110ppm, 130ppm, 150ppm, 170ppm, 190ppm, and specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and 2-80ppm is further preferred.

[0063] Preferably, after the reaction is completed, a post-treatment step is further included, and the post-treatment can reduce the content of free aliphatic isocyanate monomers in the system.

[0064] Preferably, the post-treatment method comprises any one of reduced pressure distillation, solvent-assisted distillation, co-distillation, wiped film evaporation, extraction, or a combination of at least two thereof, and reduced pressure distillation is further preferred.

[0065] The invention screens and specially designs aliphatic isocyanates so that the obtained prepolymer has a higher molecular weight and extremely low viscosity, can simplify the removal process of free aliphatic isocyanate monomers in the system, shorten the removal time, and can achieve excellent removal effect by a simple vacuum distillation method, so that the content of free aliphatic isocyanate monomers in the obtained polyurethane prepolymer composition is ≤0.3%.

[0066] Preferably, the extraction comprises molecular sieve extraction and / or solvent extraction.

[0067] Preferably, the reduced pressure distillation is thin film or stirred film distillation under vacuum.

[0068] In a preferred technical solution of the present invention, the aliphatic isocyanate is 1,5-pentamethylene diisocyanate (PDI), and the polyurethane prepolymer composition is prepared by the preparation method described above.

[0069] In another preferred technical solution of the present invention, the aliphatic isocyanate is a mixture of PDI and other aliphatic isocyanates, and the mass percentage of PDI is ≥50%; the preparation method of the polyurethane prepolymer composition includes method A or method B.

[0070] The method A comprises: reacting the aliphatic isocyanate (a mixture of PDI and other aliphatic isocyanates) with the polyol using the method described above and optionally post-treating the reaction to obtain the polyurethane prepolymer composition.

[0071] The method B comprises: reacting PDI with polyol by the method described above and optionally post-treating it to obtain prepolymer A; reacting other aliphatic isocyanate with polyol by the method described above and optionally post-treating it to obtain prepolymer B; and uniformly mixing the prepolymer A and prepolymer B to obtain the polyurethane prepolymer composition.

[0072] In a third aspect, the present invention provides a curable polyurethane composition, comprising the polyurethane prepolymer composition as described in the first aspect and a curing agent.

[0073] Preferably, the curing agent comprises polyamine and / or polyol.

[0074] Preferably, the polyol includes any one of polyester polyol, polyether polyol and small molecule polyol, or a combination of at least two of them.

[0075] Preferably, the small molecule polyol includes 1,4-butanediol (BDO) and / or hydroquinone bis(2-hydroxyethyl) ether (HQEE).

[0076] Preferably, the molar ratio of the polyurethane prepolymer composition to the curing agent is (1-1.1):1, for example, it can be 1.01:1, 1.02:1, 1.03:1, 1.04:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1 or 1.09:1, etc.

[0077] Preferably, the curable polyurethane composition further comprises a catalyst.

[0078] Preferably, the catalyst has the same selection range as above, and metal salts are further preferred, for example, it can be any one of ferrous chloride (II), ferric chloride (III), bismuth (III) 2-ethylhexanoate, bismuth (III) octanoate, bismuth (III) neodecanoate, zinc chloride, zinc 2-ethylhexanoate, tin (II) octanoate, tin (II) ethylhexanoate, tin (II) palmitate, dibutyltin (IV) dilaurate, (DBTL), dibutyltin (IV) dichloride, and lead octanoate, or a combination of at least two thereof.

[0079] Preferably, based on the sum of the masses of the polyurethane prepolymer composition and the curing agent as 100%, the mass of the catalyst is ≤5%, for example, it can be 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4% or 4.5%, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively enumerates the specific point values ​​included in the range, and it is further preferably ≤1%, and even more preferably ≤0.1%.

[0080] In a fourth aspect, the present invention provides a polyurethane product, wherein raw materials for preparing the polyurethane product include the polyurethane prepolymer composition as described in the first aspect and / or the curable polyurethane composition as described in the second aspect.

[0081] Preferably, the polyurethane product includes any one of a polyurethane elastomer, a polyurethane adhesive, a polyurethane sealant, a polyurethane foam, a polyurethane coating, and a polyurethane film.

[0082] Compared with the prior art, the present invention has the following beneficial effects:

[0083] (1) In the polyurethane prepolymer composition provided by the present invention, the prepolymer formed by the reaction of aliphatic isocyanate with polyol has a significantly reduced viscosity through the special design of the aliphatic isocyanate. The content of the second prepolymer in the polyurethane prepolymer composition is high, the molecular weight is large, the composition has low viscosity, good fluidity and excellent construction performance, and simplifies the process of removing free aliphatic isocyanate monomers during the preparation process and shortens the removal time. The polyurethane prepolymer composition is used to prepare polyurethane products, has excellent construction performance, suitable curing time, and can effectively improve the physical and mechanical properties of polyurethane products.

[0084] (2) The polyurethane film prepared from the polyurethane prepolymer composition has significantly improved physical properties, such as high tensile strength, high elongation, high hardness, and good flexibility. It can withstand bending for more than 15,000 times at a low temperature of -20°C without cracking, and can even withstand bending for more than 20,000 to 30,000 times at -20°C without cracking, and has excellent low-temperature flexibility. DETAILED DESCRIPTION

[0085] 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.

[0086] As used herein, the terms "comprises," "including," "having," "containing," or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0087] "Optionally" or "either" means that the subsequently described matter or event can or cannot occur, and that the description includes instances where the event occurs and instances where it does not.

[0088] The indefinite articles "a" and "an" before the elements or components of the present invention have no limitation on the quantity requirements (i.e. the number of occurrences) of the elements or components. Therefore, "a" or "an" should be interpreted as including one or at least one, and the elements or components in the singular form also include the plural form, unless the quantity obviously refers to the singular form only.

[0089] In the present invention, the features defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features, and are used to distinguish and describe the features, without distinction of order or importance. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0090] In the following specific embodiments of the present invention, the aliphatic isocyanate, polyol, and small molecule polyol used are all commercially available chemicals, and the average functionality of the polyol involved is 2, as follows:

[0091] Polyoxypropylene polyol, PPG1000, hydroxyl value 112 mg KOH / g, Wanol C2010D, purchased from Wanhua Chemical;

[0092] Polycaprolactone polyol, CAPA2101A, hydroxyl value 110.2 mg KOH / g, purchased from Ingevity, USA;

[0093] Polytetramethylene glycol, PTMEG1000, hydroxyl value 112 mg KOH / g, purchased from Jiaxing Hyosung Chemical;

[0094] Poly(neopentyl adipate glycol hexanediol) copolyester polyol, XCP-1000NH, with a hydroxyl value of 109.9 mg KOH / g, was purchased from Asahikawa Chemical.

[0095] In the present invention, the testing methods of the components and properties of the polyurethane prepolymer composition are as follows:

[0096] 1. Test of the content of the first prepolymer, the third prepolymer and the fourth prepolymer in the polyurethane prepolymer composition

[0097] The content of various prepolymers in the polyurethane prepolymer composition was measured by gel chromatography, and the specific method was as follows:

[0098] Instrument: Waters 150C ALC / GPC gel chromatograph

[0099] 730Data Module data processing machine

[0100] Chromatographic columns: μ-Bondagel E 100, E linear, E 125 three columns in series

[0101] Mobile phase: dimethylformamide + 3g / L NaNO 3

[0102] Measurement temperature: 45°C

[0103] Flow rate: 0.5mL / min

[0104] Sample concentration: 1 mg / mL

[0105] Injection volume: 80 μL

[0106] The sum of the contents of the third prepolymer and the fourth prepolymer is the content of the second prepolymer.

[0107] 2. Test of NCO group content in polyurethane prepolymer composition

[0108] Test the NCO group content in the polyurethane prepolymer composition according to the method in standard GB / T 33312-2016

[0109] 3. Test of the content of free aliphatic isocyanate monomer in polyurethane prepolymer composition

[0110] The free isocyanate content in the polyurethane prepolymer composition was tested according to the method in standard GB / T18446-2009 (GC method).

[0111] 4. Viscosity test of polyurethane prepolymer composition

[0112] The viscosity was tested at 25°C according to the method in standard GB / T 2794-2013.

[0113] Example 1

[0114] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PPG1000 with 1,5-pentamethylene diisocyanate (PDI). The preparation method is as follows:

[0115] Under nitrogen protection, 1540 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol PPG1000 was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤29.76%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the material was discharged by cooling to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0116]

[0117]

[0118] Example 2

[0119] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol CAPA2101A with PDI. The preparation method is as follows:

[0120] Under nitrogen protection, 1540 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol CAPA2101A was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤29.82%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0121] Viscosity (25℃, mPa·s) 3612 Content of free aliphatic isocyanate monomer (%) 0.18 NCO group content (%) 4.95 Content of the first prepolymer (%, chain number is 1) 55.37 Content of the third prepolymer (%, chain number is 2) 40.16 Content of the fourth prepolymer (%, number of chain segments>2) 4.47

[0122] Example 3

[0123] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI. The preparation method is as follows:

[0124] Under nitrogen protection, 1540 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤29.76%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the material was discharged by cooling to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0125] Viscosity (25℃, mPa·s) 2188 Content of free aliphatic isocyanate monomer (%) 0.23 NCO group content (%) 5.01 Content of the first prepolymer (%, chain number is 1) 58.69 Content of the third prepolymer (%, chain number is 2) 28.11 Content of the fourth prepolymer (%, number of chain segments>2) 13.2

[0126] Example 4

[0127] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol XCP-1000NH with PDI. The preparation method is as follows:

[0128] Under nitrogen protection, 1540 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol XCP-1000NH was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤30.04%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the material was cooled and discharged to obtain the polyurethane prepolymer composition, the component information of which is as follows:

[0129]

[0130]

[0131] Example 5

[0132] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI and 1,6-hexamethylene diisocyanate (HDI). The preparation method is as follows:

[0133] Under nitrogen protection, 840g of PDI and 840g of HDI were added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤29.63%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI and HDI monomers were removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3wt.% residual monomers, and the material was discharged after cooling to obtain the polyurethane prepolymer composition, the component information of which is as follows:

[0134] Viscosity (25℃, mPa·s) 5316 Content of free aliphatic isocyanate monomer (%) 0.29 NCO group content (%) 4.97 Content of the first prepolymer (%, chain number is 1) 60.38 Content of the third prepolymer (%, chain number is 2) 22.17 Content of the fourth prepolymer (%, number of chain segments>2) 17.45

[0135] Example 6

[0136] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI. The preparation method is as follows:

[0137] Under nitrogen protection, 770 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤18.98%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the material was discharged by cooling to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0138] Viscosity (25℃, mPa·s) 4327 Content of free aliphatic isocyanate monomer (%) 0.24 NCO group content (%) 3.75 Content of the first prepolymer (%, chain number is 1) 26.06 Content of the third prepolymer (%, chain number is 2) 51.69 Content of the fourth prepolymer (%, number of chain segments>2) 22.25

[0139] Example 7

[0140] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI. The preparation method is as follows:

[0141] Under nitrogen protection, 2310 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤35.53%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the material was discharged by cooling to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0142]

[0143]

[0144] Comparative Example 1

[0145] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol CAPA2101A with HDI. The preparation method is as follows:

[0146] Under nitrogen protection, 1680 g of HDI was added to the reactor and heated to 50° C., and 1000 g of polyol CAPA2101A was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤28.33%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual HDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual HDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0147] Viscosity (25℃, mPa·s) No liquidity Content of free aliphatic isocyanate monomer (%) 0.22 NCO group content (%) 4.69 Content of the first prepolymer (%, chain number is 1) 48.16 Content of the third prepolymer (%, chain number is 2) 45.57 Content of the fourth prepolymer (%, number of chain segments>2) 6.27

[0148] Comparative Example 2

[0149] A polyurethane prepolymer composition and a preparation method thereof, wherein the polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with HDI, and the preparation method is as follows:

[0150] Under nitrogen protection, 1680g of HDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤28.69%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual HDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3wt.% residual HDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0151] Viscosity (25℃, mPa·s) No liquidity Content of free aliphatic isocyanate monomer (%) 0.16 NCO group content (%) 4.44 Content of the first prepolymer (%, chain number is 1) 43.79 Content of the third prepolymer (%, chain number is 2) 38.64 Content of the fourth prepolymer (%, number of chain segments>2) 17.57

[0152] Comparative Example 3

[0153] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol XCP-1000NH with HDI. The preparation method is as follows:

[0154] Under nitrogen protection, 1680 g of HDI was added to the reactor and heated to 50° C., and 1000 g of polyol XCP-1000NH was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤29.72%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual HDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual HDI, and the material was cooled and discharged to obtain the polyurethane prepolymer composition, the component information of which is as follows:

[0155]

[0156]

[0157] Comparative Example 4

[0158] A polyurethane prepolymer composition and a preparation method thereof, wherein the polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with HDI, and the preparation method is as follows:

[0159] Under nitrogen protection, 840g of HDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤18.26%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual HDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3wt.% residual HDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0160] Viscosity (25℃, mPa·s) No liquidity Content of free aliphatic isocyanate monomer (%) 0.21 NCO group content (%) 3.77 Content of the first prepolymer (%, chain number is 1) 23.44 Content of the third prepolymer (%, chain number is 2) 52.36 Content of the fourth prepolymer (%, number of chain segments>2) 24.20

[0161] Comparative Example 5

[0162] A polyurethane prepolymer composition and a preparation method thereof, wherein the polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with HDI, and the preparation method is as follows:

[0163] Under nitrogen protection, 2790g of HDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤34.59%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual HDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3wt.% residual HDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0164] Viscosity (25℃, mPa·s) No fluid paste Content of free aliphatic isocyanate monomer (%) 0.13 NCO group content (%) 5.75 Content of the first prepolymer (%, chain number is 1) 83.56 Content of the third prepolymer (%, chain number is 2) 11.87 Content of the fourth prepolymer (%, number of chain segments>2) 4.57

[0165] Comparative Example 6

[0166] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with 4,4-diphenylmethane diisocyanate (MDI). The preparation method is as follows:

[0167] Under nitrogen protection, 550g of MDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤6.50%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction. Since the boiling point of MDI was too high, it was difficult to distill out the free monomer by thin film distillation, and since its saturated vapor pressure was low, the free monomer was directly retained, and the material was discharged by cooling to obtain the polyurethane prepolymer composition. When performing component analysis, the free monomer was included in the component because the monomer content was too high, and its component information is as follows:

[0168]

[0169]

[0170] Comparative Example 7

[0171] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with 4,4-dicyclohexylmethane diisocyanate (HMDI). The preparation method is as follows:

[0172] Under nitrogen protection, 580g of HMDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤6.45%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction. Since the boiling point of HMDI was too high, it was difficult to distill out the free monomer by thin film distillation, and since its saturated vapor pressure was low, the free monomer was directly retained, and the material was discharged by cooling to obtain the polyurethane prepolymer composition. When performing component analysis, the free monomer was included in the component because the monomer content was too high, and its component information is as follows:

[0173] Viscosity (25℃, mPa·s) No liquidity Content of free isocyanate monomer (%) 6.98 NCO group content (%) 6.31 Content of the first prepolymer (%, chain number is 1) 62.26 Content of the third prepolymer (%, chain number is 2) 20.47 Content of the fourth prepolymer (%, number of chain segments>2) 17.27

[0174] Comparative Example 8

[0175] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with isophorone diisocyanate (IPDI). The preparation method is as follows:

[0176] Under nitrogen protection, 500g of IPDI was added to the reactor and heated to 50°C, and 1000g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80°C until the NCO test was ≤7.01%. A total of 50ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction. Since the boiling point of IPDI was too high, it was difficult to distill out the free monomer by thin film distillation, and since its saturated vapor pressure was low, the free monomer was directly retained, and the material was discharged by cooling to obtain the polyurethane prepolymer composition. When performing component analysis, the free monomer was included in the component because the monomer content was too high, and its component information is as follows:

[0177] Viscosity (25℃, mPa·s) 9208 Content of free isocyanate monomer (%) 5.83 NCO group content (%) 6.69 Content of the first prepolymer (%, chain number is 1) 65.24 Content of the third prepolymer (%, chain number is 2) 23.39 Content of the fourth prepolymer (%, number of chain segments>2) 11.37

[0178] Comparative Example 9

[0179] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI. The preparation method is as follows:

[0180] Under nitrogen protection, 340 g of PDI was added to the reactor and heated to 50° C., and 1000 g of polyol PTMEG1000 was added at one time; the reaction was carried out at 80° C. until the NCO test was ≤7.57%. A total of 50 ppm of reaction inhibitor benzoyl chloride was added to terminate the reaction, and finally, excess residual PDI monomer was removed from the reaction product by thin film distillation under reduced pressure to a level of less than 0.3 wt.% residual PDI, and the temperature was lowered and the material was discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0181]

[0182]

[0183] Example 8

[0184] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI and HMDI. The preparation method is as follows: under nitrogen protection, 400 g of the HMDI polyurethane prepolymer composition prepared in Comparative Example 7 and 600 g of the PDI polyurethane prepolymer composition prepared in Example 3 are put into a reactor, stirred evenly at 50° C., cooled and discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0185] Viscosity (25℃, mPa·s) 6236 Content of free aliphatic isocyanate monomer (%) 2.8 NCO group content (%) 5.5 Content of the first prepolymer (%, chain number is 1) 60.06 Content of the third prepolymer (%, chain number is 2) 25.19 Content of the fourth prepolymer (%, number of chain segments>2) 14.75

[0186] Example 9

[0187] A polyurethane prepolymer composition and a preparation method thereof. The polyurethane prepolymer composition is obtained by reacting polyol PTMEG1000 with PDI and IPDI. The preparation method is as follows: under nitrogen protection, 400 g of the IPDI polyurethane prepolymer composition prepared in Comparative Example 8 and 600 g of the PDI polyurethane prepolymer composition prepared in Example 3 are put into a reactor, stirred evenly at 50° C., cooled and discharged to obtain the polyurethane prepolymer composition, and its component information is as follows:

[0188] Viscosity (25℃, mPa·s) 3062 Content of free aliphatic isocyanate monomer (%) 2.33 NCO group content (%) 5.65 Content of the first prepolymer (%, chain number is 1) 61.22 Content of the third prepolymer (%, chain number is 2) 26.29 Content of the fourth prepolymer (%, number of chain segments>2) 12.49

[0189] Application Examples

[0190] A polyurethane product, wherein the raw materials for preparing the product include a polyurethane prepolymer, a curing agent and a catalyst; the polyurethane prepolymer is the polyurethane prepolymer composition provided in Examples 1-9 and Comparative Examples 1-9, the curing agent is 1,4-butanediol, and the catalyst is dibutyltin dilaurate; the preparation method is as follows:

[0191] The polyurethane prepolymer composition is preheated to 50°C, added with 1,4-butanediol at a molar ratio of 1.05:1, and 0.05% (based on the sum of the mass of the polyurethane prepolymer and the curing agent as 100%) of dibutyltin dilaurate is added at the same time. The mixture is mixed at a high speed in a vacuum in a Speedmixer disperser for 60s, and then the mixture is poured into a mold and matured at 80°C for 8h to obtain the polyurethane product.

[0192] The aforementioned polyurethane products were cut into test pieces with a specification of 300mm×200mm×5mm and test blocks with a diameter of 50m and a height of 20mm. The samples were placed for 1 week and then the following tests were performed:

[0193] (1) Tensile properties: The tensile properties of the test piece to be tested are tested according to the method in standard ASTM D412 to obtain the tensile strength, elongation and 100% modulus of elongation;

[0194] (2) Low temperature flexibility: The test was conducted according to the method in standard GB / T 3903.41. The test piece was cut into 70 mm × 45 mm × 5 mm, the bending angle was 22.5°, the speed was 60 times / min, and the temperature was -20°C.

[0195] (3) Shore hardness: Shore A hardness and Shore D hardness were obtained by testing according to the method in GB / T 2411-2008.

[0196] The specific test results are shown in Table 1:

[0197] Table 1

[0198]

[0199]

[0200] According to the performance test results in Table 1, the present invention obtains a prepolymer by reacting an aliphatic isocyanate containing PDI with a polyol, so that the polyurethane prepolymer composition has both a large molecular weight and an extremely low viscosity. The polyurethane prepolymer composition is used to prepare a polyurethane product, and has low construction viscosity, excellent construction performance, and suitable curing time. The obtained polyurethane product has large tensile strength and 100% modulus of elongation, good elongation, high hardness, and good flexibility. It can withstand bending for more than 15,000 times at a low temperature of -20°C without cracking, and can even be bent for more than 20,000 to 30,000 times at -20°C without cracking, and has excellent low-temperature flexibility. Comparative Examples 1-5 are prepolymers prepared by reacting HDI with polyols. HDI has higher regularity than PDI, so it is easier to crystallize at low temperatures, resulting in poor low-temperature flexibility; Comparative Example 6 is a prepolymer obtained by reacting aromatic isocyanate MDI with polyols, the prepolymer of Comparative Example 7 is obtained by reacting HMDI with polyols, and the prepolymer of Comparative Example 8 is obtained by reacting IPDI with polyols. The rigidity of MDI, IPDI, and HMDI is too strong, and the hard segment T g A higher value will also lead to poor low-temperature flexibility; the polyurethane prepolymer composition of Comparative Example 9 contains an excessive amount of the second prepolymer, which leads to a too high degree of microphase separation and a decrease in the ability of physical crosslinking, thereby reducing the mechanical properties of the polyurethane.

[0201] The applicant declares that the present invention illustrates the polyurethane prepolymer composition and its preparation method and application through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned 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 prepolymer composition, characterized in that The polyurethane prepolymer composition is aliphatic isocyanate-terminated and is obtained by reacting aliphatic isocyanate with polyol, wherein the mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is ≥50%; The polyurethane prepolymer composition comprises a combination of a first prepolymer and a second prepolymer, wherein the first prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of 2:1, and the second prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of (n+1):n, wherein n≥2; The mass percentage of the second prepolymer in the polyurethane prepolymer composition is 15-75%; The molar ratio of the aliphatic isocyanate to the polyol is (2.3-15):1; The second prepolymer comprises a combination of a third prepolymer and a fourth prepolymer, wherein the third prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of 3:2, and the fourth prepolymer is an adduct of the aliphatic isocyanate and the polyol in a molar ratio of (n1+1):n1, wherein n1≥3; the mass percentage of the third prepolymer in the polyurethane prepolymer composition is 12-60%.

2. The polyurethane prepolymer composition according to claim 1, characterized in that The mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is 50-100%.

3. The polyurethane prepolymer composition according to claim 2, characterized in that The mass percentage of 1,5-pentamethylene diisocyanate in the aliphatic isocyanate is 60-100%.

4. The polyurethane prepolymer composition according to claim 1, characterized in that The aliphatic isocyanate also includes any one of 1,6-hexamethylene diisocyanate, isophorone diisocyanate, cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and cyclohexane dimethyl diisocyanate, or a combination of at least two thereof.

5. The polyurethane prepolymer composition according to claim 1, characterized in that The average functionality of the polyol is 2.

6. The polyurethane prepolymer composition according to claim 1, characterized in that: The number average molecular weight of the polyol is 300-12000 g / mol.

7. The polyurethane prepolymer composition according to claim 6, characterized in that: The number average molecular weight of the polyol is 300-3000 g / mol.

8. The polyurethane prepolymer composition according to claim 1, characterized in that: The polyol includes any one of polyester polyol, polyethylene oxide polyol, polypropylene oxide polyol, ethylene oxide-propylene oxide copolymer polyol, polytetramethylene oxide polyol, polypropylene glycol ether polyol, and vegetable oil polyol, or a combination of at least two thereof.

9. The polyurethane prepolymer composition according to claim 8, characterized in that: The polyester polyol includes polycaprolactone polyol and / or polycarbonate polyol.

10. The polyurethane prepolymer composition according to claim 1, characterized in that: The mass percentage of NCO groups in the polyurethane prepolymer composition is 2.5-15%.

11. The polyurethane prepolymer composition according to claim 1, characterized in that: The mass percentage of free aliphatic isocyanate monomers in the polyurethane prepolymer composition is ≤5%.

12. The polyurethane prepolymer composition according to claim 11, characterized in that: The mass percentage of free aliphatic isocyanate monomer in the polyurethane prepolymer composition is ≤0.5%.

13. The polyurethane prepolymer composition according to claim 1, characterized in that: The mass percentage of the first prepolymer in the polyurethane prepolymer composition is 20-80%.

14. The polyurethane prepolymer composition according to claim 13, characterized in that: The mass percentage of the first prepolymer in the polyurethane prepolymer composition is 20-60%.

15. The polyurethane prepolymer composition according to claim 1, characterized in that: The mass percentage of the third prepolymer in the polyurethane prepolymer composition is 35-60%.

16. The polyurethane prepolymer composition according to claim 15, characterized in that: The mass percentage of the third prepolymer in the polyurethane prepolymer composition is 40-60%.

17. The polyurethane prepolymer composition according to claim 1, characterized in that: The mass percentage of the fourth prepolymer in the polyurethane prepolymer composition is 3-25%.

18. The polyurethane prepolymer composition according to claim 1, characterized in that: The viscosity of the polyurethane prepolymer composition at 25° C. is ≤20000 mPa·s.

19. The polyurethane prepolymer composition according to claim 18, characterized in that: The viscosity of the polyurethane prepolymer composition at 25° C. is ≤10000 mPa·s.

20. A method for preparing the polyurethane prepolymer composition according to any one of claims 1 to 19, characterized in that: The preparation method comprises: reacting aliphatic isocyanate with polyol to obtain the polyurethane prepolymer composition.

21. The preparation method according to claim 20, characterized in that: The reaction temperature is 60-120°C.

22. The preparation method according to claim 20, characterized in that: The reaction time is 2-10 h.

23. The preparation method according to claim 20, characterized in that: The reaction is carried out in a protective atmosphere.

24. The preparation method according to claim 20, characterized in that: When the reaction reaches the end point, a reaction inhibitor is added.

25. The preparation method according to claim 24, characterized in that: The reaction inhibitor includes any one or a combination of at least two of inorganic acids, acyl chloride compounds, sulfonic acid compounds, sulfonic acid ester compounds, monoalkyl phosphates, dialkyl phosphates, and acidic compounds containing silyl groups.

26. The preparation method according to claim 24, characterized in that: Based on the sum of the masses of the aliphatic isocyanate and the polyol being 100%, the mass of the reaction inhibitor is 1-200 ppm.

27. The preparation method according to claim 26, characterized in that: Based on the sum of the masses of the aliphatic isocyanate and the polyol being 100%, the mass of the reaction inhibitor is 2-80 ppm.

28. The preparation method according to claim 20, characterized in that: After the reaction is completed, a post-treatment step is also included.

29. The preparation method according to claim 28, characterized in that: The post-treatment method includes any one of reduced pressure distillation, solvent-assisted distillation, co-distillation, wiped film evaporation, extraction, or a combination of at least two thereof.

30. A curable polyurethane composition, characterized in that The curable polyurethane composition comprises the polyurethane prepolymer composition according to any one of claims 1 to 19 and a curing agent.

31. The curable polyurethane composition according to claim 30, characterized in that The curing agent includes polyamine and / or polyol.

32. The curable polyurethane composition according to claim 30, characterized in that The curable polyurethane composition also includes a catalyst.

33. A polyurethane product, characterized in that The raw materials for preparing the polyurethane product include the polyurethane prepolymer composition according to any one of claims 1 to 19 and / or the curable polyurethane composition according to any one of claims 30 to 32.

34. The polyurethane product according to claim 33, characterized in that The polyurethane product includes any one of polyurethane elastomer, polyurethane adhesive, polyurethane sealant, polyurethane foam, polyurethane coating and polyurethane film.

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