Polyurethane composition and preparation method and use thereof

Abstract

The present invention discloses a polyurethane composition and a preparation method and use thereof. The preparation method of the polyurethane composition comprises the following steps: (1) reacting 30 to 70 parts by weight of diol and 15 to 30 parts by weight of isophorone diisocyanate in the presence of a catalyst to obtain a first prepolymer; (2) reacting the first prepolymer, 2 to 8 parts by weight of a chain extender and 0.5 to 5 parts by weight of a neutralizer to obtain a second prepolymer; (3) mixing the second prepolymer, 20 to 40 parts by weight of water and 0.5 to 3 parts by weight of an emulsifier for a first emulsification to obtain a first emulsified product; mixing the first emulsified product and 65 to 85 parts by weight of water for a second emulsification to obtain a second emulsified product; (4) reacting the second emulsified product, 2 to 6 parts by weight of a diamine chain extender and 0.5 to 4 parts by weight of a silane chain extender to obtain a polyurethane composition. The preparation method can increase the solid content of the polyurethane composition and reduce the viscosity of the polyurethane composition.

Description

Technical Field

[0001] The invention relates to a polyurethane composition and a preparation method and application thereof. Background Art

[0002] Polyurethane is one of the most widely used polymer materials. Its main chain is alternately connected with polyols through isocyanate groups of isocyanates. Due to the thermodynamic incompatibility between the isocyanate hard segment and the polyol soft segment, microphase separation is formed, which makes its aggregated structure show excellent toughness, wear resistance, low temperature resistance and impact resistance.

[0003] CN101597369A discloses a method for preparing a high-solid content polyurethane emulsion, wherein polyester polyol is subjected to a dehydration treatment, and then prepolymerized with diisocyanate and dimethylol propionic acid under the action of an organic tin catalyst to generate a prepolymer; the prepolymer is dissolved in acetone, and then a salt-forming reagent is added for neutralization, and then an alicyclic sulfonic acid type hydrophilic chain extender is added for chain extension reaction to generate a polymer; deionized water is added to the polymer for high-speed emulsification to form an emulsion, and then a diamine is added for further chain extension, and acetone is removed by vacuum to obtain a polyurethane emulsion. This method requires the use of an organic solvent, and volatile organic matter is released during the preparation and use process.

[0004] CN1869091A discloses a method for preparing waterborne polyurethane by a solvent-free method, wherein polyisocyanate, dimethylol propionic acid and polyol are stirred and reacted at 60-110°C for 2-4 hours to obtain a prepolymer containing terminal isocyanate groups; the prepolymer is cooled to 20-40°C, and under vigorous stirring, an aqueous solution containing triethylamine and a polyamine chain extender is added to the prepolymer, and the temperature is raised to 60-70°C for reaction for 1-2 hours, and the chain is extended and dispersed to obtain waterborne polyurethane. The waterborne polyurethane obtained by this method has a low solid content. Summary of the invention

[0005] In view of this, one object of the present invention is to provide a method for preparing a polyurethane composition, which can increase the solid content of the polyurethane composition and reduce the viscosity of the polyurethane composition. Further, the preparation method can improve the mechanical properties, bonding strength and solvent resistance of the polyurethane composition. Another object of the present invention is to provide a polyurethane composition. Still another object of the present invention is to provide a use of the polyurethane composition.

[0006] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0007] In one aspect, the present invention provides a method for preparing a polyurethane composition, comprising the following steps:

[0008] (1) reacting 30 to 70 parts by weight of a diol represented by formula (I) and 15 to 30 parts by weight of isophorone diisocyanate in the presence of a catalyst to obtain a first prepolymer;

[0009]

[0010] wherein m is selected from an integer of 1 to 6, n represents the degree of polymerization, and the number average molecular weight of the diol is 500 to 4000;

[0011] (2) reacting the first prepolymer, 2 to 8 parts by weight of a chain extender as represented by formula (II), and 0.5 to 5 parts by weight of a neutralizing agent to obtain a second prepolymer;

[0012]

[0013] Wherein, R1 and R2 are independently selected from C1-C6 alkylene groups, and Q is selected from an integer of 1-6;

[0014] (3) mixing the second prepolymer, 20 to 40 parts by weight of water and 0.5 to 3 parts by weight of an emulsifier for primary emulsification to obtain a first emulsified product; mixing the first emulsified product and 65 to 85 parts by weight of water for secondary emulsification to obtain a second emulsified product;

[0015] (4) reacting the second emulsified product, 2 to 6 parts by weight of a diamine chain extender and 0.5 to 4 parts by weight of a silane chain extender to obtain a polyurethane composition.

[0016] According to the preparation method of the present invention, preferably, the diamine chain extender is as shown in formula (III):

[0017]

[0018] Wherein, R3 to R5 are independently selected from C1 to C6 alkyl groups, and R6 is selected from C1 to C6 alkylene groups.

[0019] According to the preparation method of the present invention, preferably, the silane chain extender is as shown in formula (IV):

[0020]

[0021] Wherein, R7 to R9 are independently selected from C1 to C6 alkyl groups, x is selected from an integer of 1 to 6, and y is selected from an integer of 1 to 6.

[0022] According to the preparation method of the present invention, preferably, the catalyst is selected from one or more of bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, zinc neodecanoate, zinc laurate, and zinc isooctanoate;

[0023] The emulsifier is selected from one or more of sodium dodecylbenzene sulfonate, stearyl phosphate, stearyl citrate, and sodium fatty alcohol polyoxyethylene ether carboxylate;

[0024] The neutralizing agent is selected from one or more of triethylamine, tripropylamine, tributylamine, dimethylcyclohexylamine, formic acid, acetic acid, hydrochloric acid, sodium hydroxide, and epichlorohydrin.

[0025] According to the preparation method of the present invention, preferably, m is selected from an integer of 2 to 4, R1 and R2 are independently selected from C1 to C3 alkylene groups, Q is selected from an integer of 1 to 3, R3 to R5 are independently selected from C1 to C3 alkyl groups, R6 is selected from C1 to C3 alkylene groups, R7 to R9 are independently selected from C1 to C3 alkyl groups, x is selected from an integer of 2 to 4, and y is selected from an integer of 1 to 3.

[0026] According to the preparation method of the present invention, preferably, the diol is polytetrahydrofuran diol, the catalyst is bismuth isooctanoate, the link extender used in step (2) is dihydroxymethylbutyric acid, the neutralizer is triethylamine, the emulsifier is sodium fatty alcohol polyoxyethylene ether carboxylate, the diamine chain extender is isophorone diamine, and the silane chain extender is N-2-aminoethyl-3-aminopropyltriethoxysilane.

[0027] According to the preparation method of the present invention, preferably, the reaction temperature of step (1) is 70-95°C, and the reaction time is 1-8h; the reaction temperature of step (2) is 45-75°C, and the reaction time is 0.5-4h; the first emulsification time in step (3) is 2-10min, and the secondary emulsification is carried out at 20-35°C, and the secondary emulsification time is 5-20min; the reaction temperature of step (4) is 20-35°C, and the reaction time is 0.4-3h.

[0028] In another aspect, the present invention provides a polyurethane composition, which is prepared by the above preparation method.

[0029] According to the polyurethane composition of the present invention, preferably, the polyurethane composition has a solid content ≥40wt%, a viscosity ≤550cP, a tensile strength ≥40MPa, and an adhesive strength ≥50N.

[0030] In another aspect, the present invention provides use of the polyurethane composition as a coating, a coating or an adhesive.

[0031] The preparation method of the present invention does not require the use of organic solvents, thereby reducing the release of volatile organic matter during the preparation and use process. The polyurethane composition obtained by the preparation method of the present invention has a high solid content, thereby reducing the cost of drying, curing and transportation. The viscosity of the obtained polyurethane composition is low, and the paving operation is easy. The preparation method of the present invention can improve the mechanical properties, bonding strength and solvent resistance of the polyurethane composition. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] <Method for preparing polyurethane composition>

[0034] The method for preparing the polyurethane composition of the present invention comprises the following steps: (1) a primary prepolymerization step; (2) a secondary prepolymerization step; (3) an emulsification step; and (4) a chain extension step, which are described in detail below.

[0035] A pre-gathering step

[0036] The present invention reacts 30 to 70 parts by weight of diol and 15 to 30 parts by weight of isophorone diisocyanate in the presence of a catalyst to obtain a first prepolymer.

[0037] The diol of the present invention is shown in formula (I):

[0038]

[0039] In formula (I), m is an integer selected from 1 to 6, n represents the degree of polymerization, and the number average molecular weight of the diol is 500 to 4,000.

[0040] Preferably, m is selected from an integer of 2 to 4; more preferably, m is selected from an integer of 3 to 4. According to one embodiment of the present invention, the diol is polytetrahydrofuran diol.

[0041] The number average molecular weight of the diol of the present invention is 500 to 4000, preferably 1000 to 3000, and more preferably 1500 to 2500.

[0042] The amount of diol used is 30 to 70 parts by weight, preferably 40 to 60 parts by weight, and more preferably 45 to 55 parts by weight.

[0043] Preferably, the diol is first subjected to a dehydration treatment and then reacted with isophorone diisocyanate in the presence of a catalyst.

[0044] The dehydration treatment specifically comprises the following steps: vacuum dehydrating the diol at 100-150° C. for 0.5-5 h. Vacuum means that the pressure is ≤10 Pa; preferably, the pressure is ≤1 Pa; more preferably, the pressure is ≤10-1 Preferably, the dehydration is carried out at 110-130° C. Preferably, the dehydration time is 1.5-3 h.

[0045] In the present invention, the diol, isophorone diisocyanate and catalyst having a temperature of ≤70°C can be mixed. Preferably, the temperature of the diol is ≤60°C. In some embodiments, the temperature of the diol is 20 to 60°C. The diol after dehydration can be cooled to a suitable temperature under the protection of an inert gas. Examples of inert gases include, but are not limited to, nitrogen.

[0046] The diol, isophorone diisocyanate and catalyst may be reacted under stirring. The reaction temperature may be 70 to 95° C., preferably 75 to 90° C., and more preferably 80 to 85° C. The reaction time may be 1 to 8 hours, preferably 2 to 6 hours, and more preferably 3 to 4 hours.

[0047] In the present invention, the amount of isophorone diisocyanate used is 15 to 30 parts by weight, preferably 18 to 25 parts by weight, and more preferably 20 to 23 parts by weight.

[0048] The catalyst can be selected from one or more of bismuth neodecanoate, bismuth isooctanoate, bismuth laurate, zinc neodecanoate, zinc laurate, and zinc isooctanoate. According to one embodiment of the present invention, the catalyst is bismuth isooctanoate.

[0049] The amount of the catalyst used may be 0.03 to 0.2 parts by weight, preferably 0.05 to 0.15 parts by weight, and more preferably 0.08 to 0.1 parts by weight.

[0050] Secondary prepolymerization steps

[0051] The first prepolymer, 2 to 8 parts by weight of a chain extender and 0.5 to 5 parts by weight of a neutralizer are reacted to obtain a second prepolymer.

[0052] The chain extender of the present invention is shown in formula (II):

[0053]

[0054] In formula (II), R1 and R2 are each independently selected from C1-C6 alkylene groups, and Q is selected from an integer of 1-6.

[0055] Preferably, R1 and R2 are independently selected from C1 to C3 alkylene groups. Examples of alkylene groups include, but are not limited to, methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, neopentylene, n-hexylene, 2-methylpentylene, 3-methylpentylene, 2,3-dimethylbutylene, and 2,2-dimethylbutylene.

[0056] Preferably, Q is selected from an integer of 1-3; more preferably, Q is selected from an integer of 1-2.

[0057] According to one embodiment of the present invention, the chain extender is dimethylolbutyric acid.

[0058] The amount of the chain extender is preferably 3 to 7 parts by weight; more preferably 5 to 6 parts by weight.

[0059] The neutralizing agent of the present invention can be selected from one or more of triethylamine, tripropylamine, tributylamine, dimethylcyclohexylamine, formic acid, acetic acid, hydrochloric acid, sodium hydroxide, and epichlorohydrin. According to one embodiment of the present invention, the neutralizing agent is triethylamine.

[0060] The amount of the neutralizer used is preferably 1 to 4 parts by weight; more preferably 1.5 to 2 parts by weight.

[0061] The reaction temperature may be 45 to 75° C., preferably 50 to 70° C., and more preferably 60 to 65° C. The reaction time may be 0.5 to 4 h, preferably 1 to 3 h, and more preferably 2 to 2.5 h.

[0062] Specifically, the first prepolymer, the chain extender and the neutralizer are mixed at a temperature of ≤50° C. Preferably, the temperature of the first prepolymer is ≤40° C. In certain embodiments, the temperature of the first prepolymer is 20-40° C.

[0063] Emulsification steps

[0064] The second prepolymer, 20-40 parts by weight of water and 0.5-3 parts by weight of emulsifier are mixed and emulsified once to obtain a first emulsified product; the first emulsified product and 65-85 parts by weight of water are mixed and emulsified twice to obtain a second emulsified product.

[0065] The second prepolymer is directly emulsified with water and an emulsifier without cooling.

[0066] In the present invention, the emulsifier is selected from one or more of sodium dodecylbenzene sulfonate, stearyl phosphate, stearyl citrate, and sodium fatty alcohol polyoxyethylene ether carboxylate. Preferably, the emulsifier is sodium fatty alcohol polyoxyethylene ether carboxylate.

[0067] The amount of water used in the primary emulsification is preferably 25 to 35 parts by weight, and more preferably 30 to 35 parts by weight.

[0068] The amount of the emulsifier used is preferably 1 to 2.5 parts by weight; more preferably 1.5 to 2 parts by weight.

[0069] The time for one emulsification may be 2 to 10 minutes, preferably 3 to 7 minutes, and more preferably 5 to 6 minutes.

[0070] The amount of water used in the secondary emulsification is preferably 70 to 80 parts by weight, and more preferably 75 to 80 parts by weight.

[0071] The secondary emulsification temperature may be 20 to 35°C, preferably 25 to 30°C.

[0072] The secondary emulsification time may be 5 to 20 minutes, preferably 10 to 15 minutes.

[0073] Steps to chain expansion

[0074] The second emulsified product, 2 to 6 parts by weight of a diamine chain extender and 0.5 to 4 parts by weight of a silane chain extender are reacted to obtain a polyurethane composition.

[0075] The diamine-type extension connection of the present invention is shown in formula (III):

[0076]

[0077] In formula (III), R3 to R5 are independently selected from C1 to C6 alkyl groups, and R6 is selected from C1 to C6 alkylene groups. Preferably, R3 to R5 are independently selected from C1 to C3 alkyl groups. Preferably, R6 is selected from C1 to C3 alkylene groups.

[0078] Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl.

[0079] Examples of alkylene groups include, but are not limited to, methylene, ethylene, n-propylene, isopropylene, n-butylene, isobutylene, n-pentylene, isopentylene, neopentylene, n-hexylene, 2-methylpentylene, 3-methylpentylene, 2,3-dimethylbutylene, 2,2-dimethylbutylene.

[0080] According to one embodiment of the present invention, the diamine chain extender is isophorone diamine.

[0081] The amount of the diamine chain extender is preferably 3 to 5 parts by weight; more preferably 4 to 5 parts by weight.

[0082] The silane chain extender of the present invention is shown in formula (IV):

[0083]

[0084] In formula (IV), R7 to R9 are each independently selected from C1 to C6 alkyl groups, x is selected from an integer of 1 to 6, and y is selected from an integer of 1 to 6.

[0085] Preferably, R7 to R9 are independently selected from C1 to C3 alkyl groups. In certain embodiments, R7 to R9 are all ethyl groups.

[0086] Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, neopentyl, n-hexyl, 2-methylpentyl, 3-methylpentyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl.

[0087] Preferably, x is selected from an integer of 2 to 4; more preferably, x is 3. Preferably, y is selected from an integer of 1 to 3; more preferably, y is 2.

[0088] According to one embodiment of the present invention, the silane chain extender is N-2-aminoethyl-3-aminopropyltriethoxysilane.

[0089] The amount of the silane chain extender is preferably 1 to 3 parts by weight; more preferably 2 to 2.5 parts by weight.

[0090] The present invention adopts the above-mentioned diamine chain extender and silane chain extender in combination and controls the dosage within the above-mentioned range, which can improve the mechanical properties, bonding strength and solvent resistance of the polyurethane composition and can keep the polyurethane composition with a higher solid content and a lower viscosity.

[0091] The reaction temperature may be 20 to 35°C; preferably 25 to 30°C.

[0092] The reaction time may be 0.4 to 3 hours; preferably 1 to 2 hours.

[0093] <Polyurethane composition>

[0094] The polyurethane composition of the present invention is prepared by the above method.

[0095] The solid content of the polyurethane composition of the present invention is ≥40 wt %, preferably ≥45 wt %.

[0096] The viscosity of the polyurethane composition of the present invention is ≤550 cP; preferably, the viscosity is ≤450 cP. In certain embodiments, the viscosity of the polyurethane composition is 380-420 cP.

[0097] The tensile strength of the polyurethane composition of the present invention is ≥40 MPa; preferably, the tensile strength is ≥45 MPa. In certain embodiments, the tensile strength is 45 to 50 MPa.

[0098] The bonding strength of the polyurethane composition of the present invention is ≥50N; preferably, the bonding strength is ≥60N. In certain embodiments, the bonding strength is 65-70N.

[0099] The elongation of the polyurethane composition of the present invention is ≥600%; preferably, the elongation is ≥700%; more preferably, the elongation is 720-750%.

[0100] The polyurethane composition of the present invention has a 100% modulus of 5 to 15 MPa. In certain embodiments, the 100% modulus of 7 to 10 MPa.

[0101] The polyurethane composition of the present invention has good solvent resistance and is insoluble in tetrahydrofuran.

[0102] <Use of polyurethane composition>

[0103] The polyurethane composition of the present invention has high solid content and bonding strength, low viscosity, good mechanical properties and solvent resistance, and can be used as a coating, a coating or an adhesive. Therefore, the present invention provides the use of the polyurethane composition as a coating, a coating or an adhesive. The polyurethane composition of the present invention can be applied to a variety of fields such as car covers, glass protective layers, aircraft windows, aircraft cockpit covers, and precision equipment protective layers.

[0104] Here is the test method:

[0105] Solid content: According to BS EN ISO 3251-2019 Paints, varnishes and plastics - Determination of non-volatile matter content.

[0106] Viscosity: The melt viscosity at 25°C was measured using a Brookfield DV2T rotational viscometer.

[0107] Tensile strength, elongation and 100% modulus of tensile strength: measured according to the method specified in GB / T528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0108] Adhesive strength: According to the method specified in GJB-446-1988 Adhesive 90° Peel Strength Test Method.

[0109] Solvent resistance: The polyurethane composition was cured into a film and cut into square specimens of 50 mm × 50 mm. The specimens were placed in THF solvent and the dissolution of the specimens was observed after 6 hours.

[0110] Here are the raw materials:

[0111] The brand name of sodium fatty alcohol polyoxyethylene ether carboxylate is: AEC-9Na and the manufacturer is: Jining Fangyu Chemical Co., Ltd.

[0112] Example 1

[0113] (1) 50 parts by weight of polytetrahydrofuran diol having a number average molecular weight of 2000 is subjected to vacuum dehydration at 120° C. for 2 h, and then cooled to 60° C. under nitrogen protection to obtain treated polytetrahydrofuran diol. 23 parts by weight of isophorone diisocyanate and 0.08 parts by weight of bismuth isooctanoate are added to the treated polytetrahydrofuran diol, mixed well, and reacted at 85° C. for 3 h under stirring to obtain a first prepolymer.

[0114] (2) The first prepolymer was cooled to 40° C., and then 5 parts by weight of dimethylolbutyric acid and 1.5 parts by weight of triethylamine were added to the first prepolymer, and the mixture was reacted at 60° C. for 2 h to obtain a second prepolymer.

[0115] (3) Add 30 parts by weight of deionized water and 1.5 parts by weight of sodium polyoxyethylene fatty alcohol ether carboxylate to the second prepolymer for primary emulsification to obtain a first emulsified product. The primary emulsification time is 5 minutes. Add 75 parts by weight of deionized water to the first emulsified product at a temperature of 25° C. for secondary emulsification to obtain a second emulsified product. The secondary emulsification time is 10 minutes.

[0116] (4) 4 parts by weight of isophorone diamine and 2 parts by weight of N-2-aminoethyl-3-aminopropyltriethoxysilane were added to the second emulsified product and reacted at 25° C. for 1 hour to obtain a polyurethane composition.

[0117] The properties of the obtained polyurethane composition are shown in Table 1.

[0118] Comparative Example 1

[0119] Except that isophorone diamine is replaced by 1,4-butanediol, the rest is the same as Example 1.

[0120] Comparative Example 2

[0121] The same procedures as in Example 1 are followed except that 4 parts by weight of isophorone diamine and 2 parts by weight of N-2-aminoethyl-3-aminopropyltriethoxysilane in step (4) are replaced by 6 parts by weight of isophorone diamine.

[0122] Comparative Example 3

[0123] Except that the amount of isophorone diamine used in step (4) is 1 part by weight and the amount of N-2-aminoethyl-3-aminopropyltriethoxysilane used is 5 parts by weight, the rest is the same as in Example 1.

[0124] Comparative Example 4

[0125] Except that sodium fatty alcohol polyoxyethylene ether carboxylate is not used in step (3), the rest is the same as Example 1.

[0126] Table 1

[0127]

[0128] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing a polyurethane composition, characterized in that: The steps include: (1) vacuum dehydrating 50 parts by weight of polytetrahydrofuran diol having a number average molecular weight of 2000 at 120° C. for 2 h, and then cooling to 60° C. under nitrogen protection to obtain treated polytetrahydrofuran diol; adding 23 parts by weight of isophorone diisocyanate and 0.08 parts by weight of bismuth isooctanoate to the treated polytetrahydrofuran diol, mixing well, and reacting at 85° C. for 3 h under stirring to obtain a first prepolymer; (2) cooling the first prepolymer to 40° C., then adding 5 parts by weight of dimethylolbutyric acid and 1.5 parts by weight of triethylamine to the first prepolymer, and reacting at 60° C. for 2 hours to obtain a second prepolymer; (3) adding 30 parts by weight of deionized water and 1.5 parts by weight of sodium polyoxyethylene alcohol ether carboxylate to the second prepolymer for primary emulsification to obtain a first emulsified product; the primary emulsification time is 5 minutes; adding 75 parts by weight of deionized water to the first emulsified product at a temperature of 25° C. for secondary emulsification to obtain a second emulsified product; the secondary emulsification time is 10 minutes; the sodium polyoxyethylene alcohol ether carboxylate is AEC-9Na; (4) 4 parts by weight of isophoronediamine and 2 parts by weight of N-2-aminoethyl-3-aminopropyltriethoxysilane were added to the second emulsified product and reacted at 25° C. for 1 hour to obtain a polyurethane composition.

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