A two-component polyurethane adhesive composition, a preparation method and applications thereof

Abstract

The present application relates to a kind of two-component polyurethane adhesive compositions and preparation method and application, wherein, including A component and B component;The A component, with its total mass 100%, raw material mass percentage composition includes: castor oil 60-90%, multifunctional hydrogen-containing compound 4-10%, liquid polybutadiene diol 5-20%, hydrogenated castor oil 0.4-5%, polyamide wax powder 0.5-5%, defoaming agent 0.01-1%, filler 0.5-12%;The B component is the polyurethane prepolymer prepared by the reaction of polyisocyanate-based compound and polyhydroxy compound.The two-component polyurethane adhesive provided by the present application has good infiltration and permeability for membrane material, has excellent hydrolysis resistance, acid and alkali resistance, high bonding strength, and can be used as the adhesive for winding type reverse osmosis membrane module and the sealing agent for ultrafiltration membrane module.

Description

Technical Field

[0001] This invention relates to a two-component polyurethane adhesive composition and its preparation method, and its application in adhesive sealing materials for water treatment components. Background Technology

[0002] Two-component polyurethane adhesives are commonly used in reverse osmosis membrane filtration. Performance requirements include good chemical resistance, good membrane permeability, and no bubble formation during filtration and filter element washing. Generally, high membrane permeability during membrane element fabrication minimizes foaming issues during operation. Simultaneously, as an adhesive for reverse osmosis membrane sheets, it should have a specific and suitable viscosity to allow for appropriate penetration and spreading on the membrane surface. If the adhesive viscosity is too low, it tends to spread horizontally, causing capillary action or upward movement through the membrane pores at the application site, resulting in insufficient adhesion and voids on some areas of the membrane surface, failing to achieve the desired sealing effect. If the adhesive composition viscosity is too high, there will be insufficient surface penetration within the membrane and a significant interfacial transition, leading to poor adhesion. The adhesive also needs a suitable open time to allow it to penetrate and pass through the membrane before curing, achieving a good seal. In addition, since reverse osmosis membrane adhesives are exposed to complex aquatic environments such as sewage or acidic and alkaline cleaning solutions for a long time, in order to ensure a long service life of the membrane modules, the membrane module adhesives are required to have strong hydrolysis resistance and acid and alkali resistance.

[0003] CN107073402A discloses a method for preparing a spiral-wound filter module using a curable adhesive composition. The adhesive composition uses a two-component adhesive system prepared by Michael addition reaction. Compared to polyurethane adhesive compositions, this system exhibits difficulties in controlling the curing speed, poor wettability, and poor acid and alkali resistance. CN102850989A discloses a two-component polyurethane adhesive and its preparation method. Because this type of adhesive product uses hydrophobically modified fumed silica, and the hydrophobically modified segments are organopolysiloxanes, the free or dissociated polysiloxane molecules can potentially affect the service life of the adhesive layer. CN112770830A discloses a polyol composition for a two-component polyurethane adhesive used in adhesive membranes. Hydrogenated castor oil or its derivatives are used as an adhesive for reverse osmosis membrane modules to increase viscosity and provide thixotropic properties. However, the thixotropic properties provided by hydrogenated castor oil as a thixotropic agent are greatly affected by temperature, and the viscosity properties of the adhesive are easily altered by changes in ambient temperature.

[0004] Therefore, developing a two-component polyurethane adhesive composition that exhibits good adhesive properties in the application of adhesive sealing materials for water treatment components remains a problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, the present invention aims to provide a two-component polyurethane adhesive composition. By utilizing a chain extender system composed of a multifunctional hydrogen-containing compound and liquid polybutadiene glycol, and a viscosity adjustment system composed of hydrogenated castor oil and polyamide wax micropowder, the permeability and hydrolysis resistance of the two-component polyurethane adhesive are improved, thereby achieving ideal bonding strength and long service life in water treatment component applications.

[0006] Another objective of this invention is to provide a method for preparing the above-mentioned two-component polyurethane adhesive composition.

[0007] Another object of the present invention is to provide the application of the above-mentioned two-component polyurethane adhesive composition in the field of water treatment components. The adhesive has the advantages of hydrolysis resistance, acid and alkali resistance, good wettability, and high bonding strength, and is particularly suitable for bonding spiral wound reverse osmosis membranes and sealing hollow fiber filters.

[0008] To achieve the above objectives, the present invention adopts the following solution:

[0009] This invention provides a two-component polyurethane adhesive composition comprising component A and component B;

[0010] Component A, based on its total mass of 100%, comprises the following components by mass percentage:

[0011]

[0012] Component B is a polyurethane prepolymer prepared by reacting a polyisocyanate-based compound with a polyhydroxy compound.

[0013] In the adhesive composition of the present invention, the mass ratio of component A to component B is (0.7-1.2):1, preferably (0.9-1.1):1, for example 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, etc.

[0014] In the adhesive composition of the present invention, the mass ratio of the polyfunctional hydrogen-containing compound in component A to liquid polybutadiene glycol is 1:(1-3), for example 1:1, 1:1.5, 1:2, 1:2.5, 1:3, etc., which together constitute the chain extender system of the composition; the mass ratio of the hydrogenated castor oil to polyamide wax powder is (1-5):1, for example 1:1, 2:1, 3:1, 4:1, 5:1, etc., which together constitute the viscosity adjustment system of the composition.

[0015] In the adhesive composition of the present invention, the castor oil in component A is unmodified refined castor oil, preferably with a water content of less than 800 ppm, such as 800 ppm, 600 ppm, 400 ppm, 200 ppm, 100 ppm, 50 ppm, etc., and more preferably, with a water content of less than 400 ppm. The castor oil molecule contains secondary hydroxyl groups. When introduced into polyurethane adhesives, the aliphatic chains linked to the secondary hydroxyl groups can protect the urethane bonds from attack by water molecules, resulting in superior hydrolysis resistance and good hydrophobicity and hydrolytic stability. Simultaneously, because of its appropriate molecular weight, castor oil has good flowability, which is beneficial for the adhesive application process.

[0016] In the adhesive composition of the present invention, the multifunctional hydrogen-containing compound of component A has an average functionality >2, such as 2.1, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, etc., preferably >2 and ≤6, more preferably a hydrogen-containing compound with an average functionality of 2.5-3.5;

[0017] The multifunctional hydrogen-containing compound mentioned in component A refers to a multifunctional compound containing an active hydrogen reactive group, such as a polyhydroxy compound. It can be a single hydrogen-containing compound or a combination of hydrogen-containing compounds.

[0018] Preferably, the multifunctional hydrogen-containing compound is a mixture of difunctional and hydrogen-containing compounds with greater than two functions; it has the functions of both a chain extender and a crosslinking agent, wherein the chain extender is generally a hydrogen-containing compound with a functionality of 2, and the crosslinking agent is a hydrogen-containing compound with a functionality greater than 2.

[0019] The difunctional hydrogen-containing compound is a diprimary alcohol containing aliphatic branches, selected from at least one of 2-ethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,5-octanediol, 2-methyl-1,4-butanediol, and 2-ethyl-1,3-hexanediol, preferably a pentanediol containing aliphatic branches, such as 2-ethyl-1,5-pentanediol and 2,4-diethyl-1,5-pentanediol;

[0020] The greater than two functional multifunctional hydrogen-containing compound is a hydrogen-containing polyol or polyamine compound with an average functionality of 2-6, such as 2, 3, 4, 5, 6, etc., preferably 2.5-3.5; to improve the degree of crosslinking and enhance the hydrolysis resistance of the composition, the greater than two functional multifunctional hydrogen-containing compound preferably has a symmetrical structure; preferably, the greater than two functional multifunctional hydrogen-containing compound used as a crosslinking agent is selected from at least one of pentaerythritol, trimethylolpropane, sorbitol, xylitol, glycerol, tetrahydroxypropylethylenediamine, trimethylolpropane ethoxylate, and bis(trimethylolpropane), more preferably at least one of tetrahydroxypropylethylenediamine and bis(trimethylolpropane).

[0021] The multifunctional hydrogen-containing compound in component A, the liquid polybutadiene glycol, and the polyurethane prepolymer in component B react together to help form strong urethane bonds. Simultaneously, steric hindrance is established around these urethane bonds, creating a hydrophobic protective barrier with both long and short chains, reducing the likelihood of degradation and decomposition due to long-term exposure to acidic and alkaline solutions. Especially when the multifunctional hydrogen-containing compound possesses aliphatic branched chains and a symmetrical structure, its hydrolysis resistance is even more excellent.

[0022] In the adhesive composition of the present invention, the liquid polybutadiene glycol of component A has a molecular weight range of 200-2000, such as 200, 500, 1000, 1500, 2000, etc., preferably 300-1200, more preferably 300-600; preferably, the liquid polybutadiene glycol is hydroxyl-terminated liquid polybutadiene.

[0023] The liquid polybutadiene glycol in component A has good compatibility with the system. At the same time, the liquid polybutadiene glycol is a liquid telechelic polymer. After reacting with the polyurethane prepolymer in component B, it can generate a compound with a three-dimensional network structure. It works together with the multifunctional hydrogen-containing compound to form a spatial protection for the inner and outer layers of urethane bonds. The presence of this structure helps to enhance the hydrolysis resistance, acid and alkali resistance and aging resistance of the adhesive system.

[0024] Furthermore, the liquid polybutadiene glycol comprises 0-70 wt% of butadiene copolymerized with other monomers to obtain a glycol, based on the total mass of the liquid polybutadiene glycol, for example 0 wt%, 0.1 wt%, 1 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, etc.; the liquid polybutadiene glycol in component A can be a glycol obtained by self-polymerization of butadiene monomers (HTPB), or it can contain a glycol obtained by copolymerization of butadiene with other monomers. The introduction of its comonomers helps to further improve the mechanical, water resistance and temperature resistance properties of the adhesive layer;

[0025] Preferably, the diol obtained by copolymerizing butadiene with other monomers is selected from the diol obtained by copolymerizing butadiene with at least one of propylene, acrylic acid, isobutylene, 1,4-pentadiene, and isoprene, such as butadiene-acrylic acid copolymer diol and butadiene-pentadiene copolymer diol.

[0026] In the adhesive composition of this invention, the hydrogenated castor oil in component A refers to hydrogenated castor oil, for example, castor oil obtained by catalytic hydrogenation under the action of a metal catalyst, reducing the unsaturated fatty acids to saturated fatty acids. Hydrogenated castor oil is an existing product in the field, and this invention does not have any particular requirements regarding its source. The hydroxyl groups on the fatty acid chains of hydrogenated castor oil can swell and gel. The swollen particles are bonded by weak hydrogen bonds due to the polar groups in the hydrogenated castor oil molecules, forming a thixotropic network structure.

[0027] In the adhesive composition of the present invention, the polyamide wax micro powder in component A is a powder particle of polyamide wax, which is usually obtained by directly pulverizing solid wax products or cooling molten liquid wax atomization. It is an existing product in the field, and the present invention does not have any special requirements for its source; the particle size of the polyamide wax micro powder is ≤10 micrometers, for example 10 micrometers, 8 micrometers, 6 micrometers, 4 micrometers, 2 micrometers, etc., preferably ≤7 micrometers;

[0028] Preferably, the molecular weight of the polyamide wax micro powder is 400-3000, such as 400, 1000, 1500, 2000, 2500, 3000, etc., more preferably 500-2000, and more preferably 700-900;

[0029] Preferably, the polyamide wax micropowder is selected from products prepared by reacting hydroxy fatty acids, caprolactam, and diamines; more preferably, the hydroxy fatty acids are selected from at least one of hydroxyvalerate, hydroxyheptanoic acid, sinapic acid, ricinoleic acid, hydroxyoctanoic acid, hydroxynonanoic acid, hydrogenated ricinoleic acid (also known as 12-hydroxystearic acid), 9,10-dihydroxystearic acid, etc.; the diamine is an aliphatic diamine, selected from at least one of 1,3-propanediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,10-decanediamine, dodecyldiamine, etc.

[0030] More preferably, the polyamide wax micro powder is selected from the product prepared by reacting hydrogenated ricinoleic acid, caprolactam and 1,6-hexanediamine, such as NEW-0421.

[0031] The polyamide wax and hydrogenated castor oil selected in this invention have similar segment and group structures. They work synergistically with the hydrogenated castor oil to form more extended segments, resulting in a more complete interpenetrating hydrogen bond system, thus enhancing the thixotropic effect. Because the polyamide wax and hydrogenated castor oil compound contains abundant hydroxyl and amide groups, their combination can form strong intermolecular hydrogen bonds. The nonpolar chains in the polyamide wax and the hydrogenated castor oil intertwine to form a network structure. When subjected to external stress, the network structure breaks down into individual independent units; when the external stress or shear force disappears, the molecules reform the intertwined network structure. Meanwhile, the combination of polyamide wax and hydrogenated castor oil also solves the problem of low solubility of polyamide wax in general systems. The synergistic use of hydrogenated castor oil can achieve good thixotropic effects with relatively small dosage and relatively low viscosity, and promotes intermembrane penetration. This can improve adhesion and reduce the possibility of interface defects. At the same time, the interaction between the two makes it easier to add and avoids the migration of unreacted substances and temperature sensitivity of the adhesive solution. This helps the adhesive maintain good bond strength without decay and improves the resistance of the adhesive system to acid and alkali media.

[0032] From the perspective of the interaction between the adhesive and the bonding substrate, hydrogenated castor oil and polyamide wax exhibit good interaction and compatibility with the polyester support layer, polysulfone layer, and polyamide reverse osmosis functional layer. This helps to improve the adhesion between the adhesive and the reverse osmosis membrane, enhance water resistance, and prolong the adhesive layer's lifespan. Furthermore, in this adhesive system, the use of hydrogenated castor oil can improve the thixotropy of the adhesive system. However, the use of hydrogenated castor oil alone can make the system's transparency and viscosity more susceptible to temperature changes. Surprisingly, in the system of this invention, due to the use of polyamide wax micropowder, the temperature sensitivity caused by hydrogenated castor oil is almost non-existent. The thixotropy provided by the combined use of hydrogenated castor oil and polyamide wax is less dependent on temperature and less sensitive to seasonal and environmental requirements, which is beneficial to adhesive stability.

[0033] In the adhesive composition of the present invention, the defoamer and filler of component A can be conventionally selected in the art. In some specific examples of the present invention, the range of selectable defoamers and fillers is as follows:

[0034] The defoaming agent is selected from organic polymers, preferably at least one of organosilicon polymers, higher alcohol fatty acid esters, and polyoxyethylene polyoxypropylene amine ethers. The defoaming agent functions to accelerate the migration of air bubbles present inside the adhesive to the liquid surface during the defoaming stage before application, thus promoting bubble removal. Available commercial brands include at least one of TEGO Airex 920 and BYK A 530.

[0035] The packing material is selected from ultrafine molecular sieves, preferably 3A molecular sieves;

[0036] Preferably, the average particle size of the filler is 3-20 micrometers, such as 3 micrometers, 6 micrometers, 9 micrometers, 12 micrometers, 15 micrometers, 18 micrometers, 20 micrometers, etc., more preferably 5-7 micrometers. Due to the porous nature of the molecular sieve, the molecular sieve reduces the possibility of air bubbles being generated in the adhesive solution during use while removing moisture, making the adhesive solution more uniform and reducing product defects.

[0037] In the adhesive composition of the present invention, the polyisocyanate-based compound of component B is selected from at least one of aliphatic, alicyclic, and aromatic difunctional or polyfunctional isocyanates, preferably at least one of 4,4'-diphenylmethane diisocyanate (4,4'-MDI), 2,4'-diphenylmethane diisocyanate (2,4'-MDI), 4,4'-dicyclohexylmethane diisocyanate, 1,4-tetraphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate, more preferably at least one of 4,4'-MDI and 2,4'-MDI;

[0038] Further, the polyisocyanate-based compound optionally comprises 0-20 wt% of carbodiimide and / or urea-ketimide-modified polyisocyanate, based on the total mass of the polyisocyanate-based compound, for example, comprising 0.1 wt%, 1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% of carbodiimide and / or urea-ketimide-modified polyisocyanate.

[0039] In the adhesive composition of the present invention, the polyhydroxy compound of component B is a polyol compound, preferably a polymeric polyol, such as a polyether polyol or a polyester polyol;

[0040] Preferably, the polyhydroxy compound is at least one of polypropylene oxide polyol and castor oil;

[0041] Preferably, the molecular weight of the polyhydroxy compound is 500-2500, such as 500, 1000, 1500, 2000, 2500, etc., and more preferably 500-1500;

[0042] Preferably, the functionality of the polyhydroxy compound is 2-3, such as 2, 2.5, 3, etc.

[0043] In the adhesive composition of the present invention, the mass percentage of the polyisocyanate-based compound in component B is 45-70%, for example 45%, 50%, 55%, 60%, 65%, 70%, etc., preferably 58-63%, based on the total mass of component B.

[0044] In the adhesive composition of the present invention, component B, the polyurethane prepolymer, comprises isocyanate groups (NCO) accounting for 10-20% of the total mass, for example, 10%, 12%, 14%, 16%, 18%, 20%, etc., preferably 13-17%.

[0045] The adhesive composition of the present invention may optionally include other additives, such as catalysts, wetting agents, defoamers, inorganic fillers, antistatic agents, etc., which are all conventional choices in the field, and the present invention does not specifically limit their types.

[0046] In a second aspect, the present invention provides a method for preparing the above-described two-component polyurethane adhesive composition.

[0047] Specifically, the two-component polyurethane adhesive composition of the present invention can be obtained by the following preparation method, the steps of which include:

[0048] (1) Preparation of component A: Castor oil, polyfunctional hydrogen-containing compound, and liquid polybutadiene glycol are mixed evenly and heated to 60-70℃, such as 60℃, 62℃, 64℃, 66℃, 68℃, 70℃, etc. Hydrogenated castor oil, polyamide wax powder, defoamer, and filler are added and mixed evenly. The mixture is then cooled to 30-40℃, such as 30℃, 32℃, 34℃, 36℃, 38℃, 40℃, etc., and defoamed under vacuum to obtain component A.

[0049] (2) Preparation of component B: Mix the polyisocyanate compound and the polyhydroxy compound evenly, and react at 70-85℃, for example, 70℃, 73℃, 76℃, 80℃, 83℃, 85℃, etc. for 2-5h, for example, 2h, 3h, 4h, 5h, etc., to obtain the polyurethane prepolymer, i.e. component B.

[0050] In this invention, when mixing castor oil, polyfunctional hydrogen-containing compound and liquid polybutadiene glycol in step (1), the stirring speed is 2-30 rpm, such as 2 rpm, 10 rpm, 20 rpm, 30 rpm, etc., and the stirring time is 30-90 min, such as 30 min, 50 min, 70 min, 90 min, etc.

[0051] After adding hydrogenated castor oil, polyamide wax powder, defoamer, and filler, wait until the solid substances are basically wetted by the liquid raw materials, and then continue stirring for 1.5-2 hours, such as 1.5 hours, 1.7 hours, 1.9 hours, 2 hours, etc.

[0052] In this invention, the vacuum degassing in step (1) is performed with a vacuum degree lower than 1500 Pa, such as 1400 Pa, 1200 Pa, 1000 Pa, 800 Pa, etc. The degassing time is determined according to the volume of the vessel until no bubbles escape from the surface.

[0053] In this invention, in step (1), for ease of addition, hydrogenated castor oil and polyamide wax powder can be premixed in castor oil in a certain proportion to obtain a viscous liquid or paste.

[0054] In this invention, the polyisocyanate compound in step (2) is fed at a constant temperature of 40-50℃, such as 40℃, 45℃, 50℃, etc.

[0055] When using the above-mentioned two-component polyurethane adhesive composition of the present invention, the separately prepared components A and B are mixed uniformly in a certain proportion, applied to the surface of the substrate or potted and bonded, and cured to prepare a component.

[0056] Preferably, the mixture obtained by mixing component A and component B has a non-flow time (i.e., working time) of 30-60 min, more preferably 40-50 min, and a curing time of 20-30 h.

[0057] A third aspect of the present invention provides the application of the above-described two-component polyurethane adhesive composition in the field of water treatment components, particularly suitable for bonding and sealing of wound reverse osmosis membrane modules and hollow fiber potting modules.

[0058] Compared with the prior art, the beneficial effects of the two-component polyurethane adhesive composition of the present invention are as follows:

[0059] Based on castor oil as the base material, this invention achieves superior hydrolysis and acid / alkali resistance in the cured adhesive material by combining multifunctional hydrogen-containing compounds, liquid polybutadiene glycol, hydrogenated castor oil, and polyamide wax micropowder in component A. This reduces the failure risk of the adhesive as a sealing or bonding adhesive for reverse osmosis membrane components, and improves its service life and reliability.

[0060] In a preferred embodiment of the present invention, when the adhesive composition uses liquid polybutadiene glycol, a primary diol containing aliphatic branches, and a polyfunctional alcohol crosslinking agent with a symmetrical structure to form a hydrogen-containing compound system, the hydroxyl groups and structural steric hindrance react with isocyanates to form an adhesive system with a certain crosslinking density and high reaction strength under the protection of inner and outer network layers, giving the adhesive product excellent water resistance and acid and alkali resistance. In particular, when liquid polybutadiene glycol is introduced into diols obtained by copolymerizing butadiene with other monomers, its copolymer structure helps to further improve the mechanical, water resistance, and temperature resistance properties of the adhesive layer.

[0061] This invention uses polyamide wax and hydrogenated castor oil instead of fumed silica to provide thixotropy without significantly increasing flow viscosity. The relatively low viscosity helps improve the wetting of the adhesive solution at the substrate interface, potentially improving adhesion and reducing interfacial defects. Furthermore, since the adhesive composition of this invention does not use fumed silica as a thixotropic modifier, the introduction of organopolysiloxane compounds is avoided, eliminating the risk of decreased interlayer bond strength or separation due to polysiloxane migration during long-term use, thus improving adhesive strength. Detailed Implementation

[0062] The following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known modifications within the scope of the claims of the present invention.

[0063] The main raw material sources in the embodiments and comparative examples of this invention are as follows; unless otherwise specified, all other raw materials were obtained through ordinary commercial channels:

[0064] Refined castor oil: moisture content <400ppm, hydroxyl value 160mgKOH / g, acid value <3mgKOH / g, functionality 3, purchased from Huanyu Oils;

[0065] Hydrogenated castor oil: white to pale yellow powder, hydroxyl value 150-165 mgKOH / g, iodine value ≤5, melting point 85-88℃, purchased from Huanyu Oils;

[0066] Liquid polybutadiene glycol 1: molecular weight 470-530, colorless or pale yellow liquid, purchased from Maclean's reagents;

[0067] Liquid polybutadiene glycol 2: Molecular weight 500-800, comprising 55 wt% butadiene copolymerized with isoprene, based on the total mass of the liquid polybutadiene glycol; prepared by the following method:

[0068] ① Butadiene and isoprene monomers undergo ionic polymerization using butyllithium as a catalyst, 2,2-ditetrahydrofuran ether as a polarity modifier, and toluene as a solvent to obtain a copolymer; ② Oxidation is performed using m-chloroperoxybenzoic acid to obtain epoxidized polybutadiene-isoprene; ③ Further oxidation with periodic acid yields an aldehyde-terminated copolymer; ④ Reduction with sodium borohydride yields a hydroxyl-terminated copolymer. The molecular weight of the copolymer is controlled by adjusting the epoxidation rate.

[0069] Multifunctional hydrogen-containing compound 1: 2,4-diethyl-1,5-pentanediol, functionality 2, liquid, purchased from Aladdin Reagents;

[0070] 2. Multifunctional hydrogen-containing compound: bis(trimethylolpropane), functionality 4, purchased from Aladdin Reagent;

[0071] Fumed silica: Aerosil R805, polydimethylsiloxane modified fumed silica, purchased from Evonik;

[0072] Polyamide wax micro powder: NEW-0421, average particle size (D50) 5μm, molecular weight 680, purchased from Nanjing Tianshi New Materials;

[0073] Defoaming agent: BYK A535, polymer (siloxane-free), purchased from BYK Chemicals;

[0074] Packing material: 3A molecular sieve, average particle size 6 micrometers, purchased from Shanghai Guangji;

[0075] Isocyanate 1: 4,4-diphenylmethane diisocyanate, purchased from Wanhua Chemical;

[0076] Isocyanate 2: Carbodiimide-modified 4,4-diphenylmethane diisocyanate, purchased from Wanhua Chemical;

[0077] Polypropylene oxide glycol: average molecular weight 1000, functionality 2, purchased from Wanhua Chemical.

[0078] Examples and Comparative Examples

[0079] Examples B1-B2

[0080] Preparation of component B

[0081] In a reactor equipped with stirring and temperature control, the raw materials are added according to the mass percentages in Table 1 below. The specific steps are as follows: add polypropylene glycol and / or refined castor oil to the reactor, preheat at a constant temperature of 45°C, then add isocyanate 1, react at a constant temperature of 70-85°C for 2-3 hours, add isocyanate 2, and continue to react at a constant temperature with stirring for 0.5 hours to obtain the polyurethane prepolymer of component B. Measure the NCO index, cool down and discharge the material.

[0082] Table 1. Raw material ratios (mass percentage%) of component B in Examples B1-B2

[0083] Component B number B1 B2 Isocyanate 1 48 51 Isocyanate 2 12 12 Polypropylene glycol 22 - Refined castor oil 18 37 NCO content % 15.36 15.65

[0084] Examples A1-A12 and Comparative Examples C1-C2

[0085] Preparation of component A

[0086] Add the raw materials according to the mass percentages in Table 2 below. The specific steps are as follows: At room temperature, add refined castor oil, polyfunctional hydrogen-containing compounds, and liquid polybutadiene glycol to the double planetary mixing vessel in sequence. Close the vessel body, start stirring, and mix for 30 minutes at a speed of 2-30 rpm. Raise the temperature inside the vessel to 60-70℃, open the vessel lid, and add hydrogenated castor oil, polyamide wax powder, defoamer, and filler in sequence. After the solid substances are basically wetted by the liquid raw materials, continue stirring for 1.5-2 hours. Cool down to 30-40℃, remove air bubbles by vacuuming, with the vacuum degree below 1500Pa, until no air bubbles escape from the surface, and then discharge the material.

[0087] Table 2. Raw material ratios (mass percentage) of component A in Examples A1-A12 and Comparative Examples C1-C2

[0088]

[0089]

[0090] Examples 1-13 and Comparative Examples 1-2

[0091] Preparation and application of two-component polyurethane adhesive compositions: Mix and cure component A and component B according to the proportions in Table 3.

[0092] Components A and B were mixed uniformly according to the proportions in Table 3 to prepare sample pieces or blocks of a certain type. The non-flow time and curing time of the adhesive were tested, and then mechanical, hardness and other properties were tested. The ambient temperature was controlled at 23-25℃ and the ambient humidity at 50-75%. The results are shown in Table 4.

[0093] Table 3. Ratios of component A and component B in Examples 1-13 and Comparative Examples 1-2

[0094]

[0095]

[0096] Performance testing

[0097] (1) Non-flowing time

[0098] Mix components A and B (mass and 100g) according to the calculated ratio. Mix them quickly and evenly in a homogenizer at 2000rpm for 1min. Place the mixture on a table and start timing. When the liquid surface in the tilted container stops flowing, the timing is complete, which is the non-flow time.

[0099] (2) Gel curing time

[0100] The time it took for the curing viscosity to reach 100 Pa·s was measured using a Brookfield CAP2000+ cone-plate viscometer.

[0101] (3) Shore A hardness test

[0102] According to the method of GB / T531.1-2008 Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Shore A, the hardness was tested at 24h, 72h and 1 week of curing.

[0103] (4) Thixotropic ratio

[0104] For the polyol composition (A), a rheometer was used to measure the shear frequency from 1 s⁻¹ to 50 s⁻¹. The fluid viscosity at 1 s⁻¹ divided by the fluid viscosity at 10 s⁻¹ (1 / 10) and the fluid viscosity at 2 s⁻¹ divided by the fluid viscosity at 20 s⁻¹ (2 / 20) were calculated and recorded as thixotropic ratios of 1 / 10 and 2 / 20, respectively.

[0105] (5) Acid resistance test

[0106] Prepare an HCl aqueous solution with pH=1, solidify the adhesive to prepare a strip sample block of 75×25×5mm, completely immerse it in the prepared HCl solution, and place it at room temperature of 25℃ for at least one month. Take it out every 7 days, wipe it clean, and measure the mass change rate of the sample block.

[0107] (6) Alkali resistance test

[0108] Prepare a NaOH solution with pH=13.5, solidify the adhesive solution to prepare a strip sample block of 75×25×5mm, completely immerse it in the prepared NaOH solution, heat it in a constant temperature oven at 50℃, and leave it for at least one month. Take it out every 7 days, wipe it clean, and measure the mass change rate of the sample block.

[0109] (7) Mechanical strength test

[0110] The prepared A / B component adhesive solutions were mixed in a certain proportion to obtain a sample with a thickness of 5 mm. The sample was tested according to the methods of "GB / T528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber" and "GB / T 529-2008 Determination of tear strength of vulcanized rubber or thermoplastic rubber", and the tensile strength, elongation at break and tear strength indicators were achieved respectively.

[0111] (8) Permeability test

[0112] The prepared A / B adhesive mixture was placed on the surface of the nonwoven fabric layer of the reverse osmosis membrane. Within a specific time range, the contact angle and mass reduction of the adhesive on the membrane surface were measured, and the percentage of permeate mass was calculated. The KRUSSDSA25S contact angle meter was used for testing.

[0113] (9) Bond strength

[0114] The prepared A / B adhesive is used to bond a PVC sheet (length × width × thickness: 20 × 5 × 0.5 mm), with a bonding area of ​​5 × 5 cm². The end of the PVC sheet is held by a tensile testing machine, and the strength of the bonded surface is tested by tensile testing.

[0115] Table 4. Comparison of test items and results between examples and comparative examples of two-component polyurethane adhesive compositions.

[0116]

[0117]

[0118] As can be seen from the data in Table 4, the embodiments of the present invention, especially the selected branched chain extender / crosslinker type and its combination with polybutadiene glycol, provide high mechanical and adhesive strength through the protection of inner and outer layers and a certain crosslinking density, while also helping to reduce the decomposition of the system by acid and alkali media. Furthermore, when liquid polybutadiene glycol is introduced into the diol obtained by copolymerizing butadiene with other monomers, its copolymer structure helps to further improve the mechanical, water-resistant, and temperature-resistant properties of the adhesive layer. The combined use of polyamide wax and hydrogenated castor oil provides sufficient thixotropy, and due to the presence of their own reactive groups and their hydrophobic properties, it promotes and improves the acid and alkali hydrolysis resistance of the material, which is superior to the traditional non-reactive thixotropic system using only fumed silica. On the other hand, the design of this system ensures that the raw materials and related polymers are compatible with the reverse osmosis membrane layer molecules. The adhesive system of the present invention exhibits high permeability on the reverse osmosis membrane surface, manifested as a relatively low contact angle and a high percentage of permeate mass over the same time, thus validating the expectations of the present invention.

Claims

1. A two-component polyurethane adhesive composition, characterized in that, Includes component A and component B; Component A, based on its total mass of 100%, comprises the following components by mass percentage: Castor oil 60-85%; Polyfunctional hydrogen-containing compounds: 4-10%; Liquid polybutadiene glycol 5-20%; Hydrogenated castor oil 0.4-5%; Polyamide wax micro powder 0.5-5%; Defoamer 0.01-1%; Filler content: 0.5-12%; The multifunctional hydrogen-containing compound is a mixture of a difunctional hydrogen-containing compound and a hydrogen-containing compound with greater than two functions; the difunctional hydrogen-containing compound is a diol containing aliphatic branches, and the multifunctional hydrogen-containing compound with greater than two functions has a symmetrical structure. The liquid polybutadiene glycol comprises 0.1-70 wt% of butadiene copolymerized with other monomers to obtain a glycol, based on the total mass of the liquid polybutadiene glycol; Component B is a polyurethane prepolymer prepared by reacting a polyisocyanate-based compound with a polyhydroxy compound.

2. The two-component polyurethane adhesive composition according to claim 1, characterized in that, Component A, based on its total mass of 100%, comprises the following components by mass percentage: Castor oil 65-85%; Polyfunctional hydrogen-containing compounds: 4-8%; Liquid polybutadiene glycol 7.2-12%; Hydrogenated castor oil 1.2-3.3%; Polyamide wax micro powder 1.3-3.5%; Defoamer 0.01-0.2%; Packing material 1.3-8%.

3. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The mass ratio of component A to component B is (0.7-1.2):1; and / or The mass ratio of the multifunctional hydrogen-containing compound to liquid polybutadiene glycol is 1:(1-3); and / or The mass ratio of hydrogenated castor oil to polyamide wax micro powder is (1-5):

1.

4. The two-component polyurethane adhesive composition according to claim 3, characterized in that, The mass ratio of component A to component B is (0.9-1.1):

1.

5. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The multifunctional hydrogen-containing compound is a hydrogen-containing compound with an average functionality greater than 2; the multifunctional hydrogen-containing compound with greater than two functions has an average functionality of 2 to 6 and not equal to 2; and / or The liquid polybutadiene glycol has a molecular weight range of 200-2000.

6. The two-component polyurethane adhesive composition according to claim 5, characterized in that, The multifunctional hydrogen-containing compound is a hydrogen-containing compound with an average functionality greater than 2 and less than or equal to 6.

7. The two-component polyurethane adhesive composition according to claim 6, characterized in that, The multifunctional hydrogen-containing compound is a hydrogen-containing compound with an average functionality of 2.5-3.

5.

8. The two-component polyurethane adhesive composition according to claim 5, characterized in that, The molecular weight range of the liquid polybutadiene glycol is 300-1200.

9. The two-component polyurethane adhesive composition according to claim 5, characterized in that, The molecular weight range of the liquid polybutadiene glycol is 300-600.

10. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The difunctional hydrogen-containing compound is selected from at least one of 2-ethyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-methyl-2,4-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl-1,5-octanediol, 2-methyl-1,4-butanediol, and 2-ethyl-1,3-hexanediol.

11. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The difunctional hydrogen-containing compound is selected from pentanediols containing aliphatic branches.

12. The two-component polyurethane adhesive composition according to claim 11, characterized in that, The difunctional hydrogen-containing compound is selected from 2-ethyl-1,5-pentanediol and 2,4-diethyl-1,5-pentanediol.

13. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The average functionality of the multifunctional hydrogen-containing compounds with greater than two functions is 2.5 to 3.

14. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The multifunctional hydrogen-containing compound with greater than two functions is selected from at least one of pentaerythritol, trimethylolpropane, sorbitol, xylitol, glycerol, tetrahydroxypropylethylenediamine, trimethylolpropane ethoxylate, and bis(trimethylolpropane).

15. The two-component polyurethane adhesive composition according to claim 14, characterized in that, The multifunctional hydrogen-containing compound with greater than two functions is selected from at least one of tetrahydroxypropylethylenediamine and bis(trimethylolpropane).

16. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The diol obtained by copolymerizing butadiene with other monomers is selected from the diol obtained by copolymerizing butadiene with at least one of propylene, acrylic acid, isobutene, 1,4-pentadiene, and isoprene.

17. The two-component polyurethane adhesive composition according to claim 16, characterized in that, The diol obtained by copolymerizing butadiene with other monomers is selected from butadiene / acrylic acid copolydiol and butadiene / 1,4-pentadiene copolydiol.

18. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The castor oil has a water content of less than 800 ppm; and / or The polyamide wax micro powder has a particle size of ≤10 micrometers.

19. The two-component polyurethane adhesive composition according to claim 18, characterized in that, The castor oil has a moisture content of less than 400 ppm.

20. The two-component polyurethane adhesive composition according to claim 18, characterized in that, The polyamide wax micropowder has a particle size of ≤7 micrometers.

21. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The molecular weight of the polyamide wax micropowder is 400-3000.

22. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The molecular weight of the polyamide wax micropowder is 500-2000.

23. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The molecular weight of the polyamide wax micropowder is 700-900.

24. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The defoaming agent is selected from at least one organic polymer; and / or The packing material is selected from ultrafine molecular sieves.

25. The two-component polyurethane adhesive composition according to claim 24, characterized in that, The defoaming agent is selected from at least one of organosilicon polymers, higher alcohol fatty acid esters, and polyoxyethylene polyoxypropylene amine ethers.

26. The two-component polyurethane adhesive composition according to claim 24, characterized in that, The packing material is 3A molecular sieve.

27. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The average particle size of the filler is 3-20 micrometers.

28. The two-component polyurethane adhesive composition according to claim 27, characterized in that, The average particle size of the filler is 5-7 micrometers.

29. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The polyisocyanate compound is selected from at least one of aliphatic, alicyclic, and aromatic difunctional or polyfunctional isocyanates; and / or The polyisocyanate-based compound optionally comprises 0-20 wt% of carbodiimide and / or urea-ketimide-modified polyisocyanate, based on the total mass of the polyisocyanate-based compound; and / or The polyhydroxy compound is a polyol compound.

30. The two-component polyurethane adhesive composition according to claim 29, characterized in that, The polyisocyanate-based compound is selected from at least one of 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-tetraphenylmethane diisocyanate, 1,6-hexamethylene diisocyanate, 2,4-toluene diisocyanate, and 2,6-toluene diisocyanate.

31. The two-component polyurethane adhesive composition according to claim 30, characterized in that, The polyhydroxy compound is a polymeric polyol.

32. The two-component polyurethane adhesive composition according to claim 31, characterized in that, The polyhydroxy compound is at least one of polypropylene oxide polyol and castor oil.

33. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The molecular weight of the polyhydroxy compound is 500-2500.

34. The two-component polyurethane adhesive composition according to claim 33, characterized in that, The molecular weight of the polyhydroxy compound is 500-1500.

35. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The functionality of the polyhydroxy compound is 2-3.

36. The two-component polyurethane adhesive composition according to claim 1, characterized in that, The polyisocyanate group compound in component B accounts for 45-70% by mass, based on the total mass of component B; and / or Component B is the polyurethane prepolymer, wherein isocyanate groups (NCO) account for 10-20% of the total mass.

37. The two-component polyurethane adhesive composition according to claim 36, characterized in that, The mass percentage of the polyisocyanate group compound in component B is 58-63%, based on the total mass of component B.

38. The two-component polyurethane adhesive composition according to claim 36, characterized in that, Component B is the polyurethane prepolymer, wherein isocyanate groups (NCO) account for 13-17% of the total mass.

39. A method for preparing a two-component polyurethane adhesive composition according to any one of claims 1-38, characterized in that the step... include: (1) Preparation of component A: Castor oil, polyfunctional hydrogen-containing compound, and liquid polybutadiene glycol are mixed evenly, heated to 60-70℃, hydrogenated castor oil, polyamide wax powder, defoamer, and filler are added and mixed evenly, cooled to 30-40℃, and defoamed under vacuum to obtain component A; (2) Preparation of component B: Mix the polyisocyanate compound and the polyhydroxy compound evenly and react at 70-85℃ for 2-5 hours to obtain the polyurethane prepolymer, i.e. component B.

40. The method for preparing the two-component polyurethane adhesive composition according to claim 39, characterized in that, In step (1), when mixing castor oil, polyfunctional hydrogen-containing compounds, and liquid polybutadiene glycol, the stirring speed is 2-30 rpm and the stirring time is 30-90 min. After adding hydrogenated castor oil, polyamide wax powder, defoamer, and filler, wait until the solids are basically wetted by the liquid raw materials, then continue stirring for 1.5-2 hours; and / or The vacuum degassing in step (1) is performed with a vacuum level below 1500 Pa; and / or In step (2), the polyisocyanate compound is fed at a constant temperature of 40-50℃.

41. The use of the two-component polyurethane adhesive composition according to any one of claims 1-38 or the two-component polyurethane adhesive composition prepared by the method of claim 39 or 40 in the field of water treatment components.

42. The application according to claim 41, characterized in that, Suitable for bonding and sealing of wound-wound filter membrane modules and hollow fiber ultrafiltration filtration modules.

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