Bi-component polyurethane adhesive for bonding composite material and preparation method of bi-component polyurethane adhesive

Abstract

The invention discloses a two-component polyurethane adhesive for bonding a composite material and a preparation method of the two-component polyurethane adhesive. The two-component polyurethane adhesive comprises a component A and a component B, wherein the component A is prepared from 20-40 parts of hydroxyl-terminated polyurethane prepolymer, 10-30 parts of polyhydric alcohol I, 20-35 parts of polyhydric alcohol II, 1-1.5 parts of pigment, 0.1-0.4 part of a catalyst, 1-2 parts of a coupling agent, 2-5 parts of a thixotropic agent, 3-8 parts of a water removal agent and 10-20 parts of filler; and the component B comprises the following components in parts by weight: 30-40 parts of isocyanate I, 30-50 parts of an isocyanate-terminated polyurethane prepolymer, 2-8 parts of a thixotropic agent and 20-30 parts of filler. The bi-component polyurethane adhesive for bonding the composite material has the advantages of high bonding strength, no polishing and the like, and has a good bonding effect on pultrusion profiles of different matrix resins (an epoxy anhydride system, a polyurethane system and an unsaturated polyester system).

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and more specifically, relates to a two-component polyurethane adhesive for bonding composite materials and a preparation method thereof. Background Art

[0002] Polyurethane adhesive is a common composite adhesive. Compared with epoxy adhesive, polyurethane has good toughness and bonding performance; compared with acrylic adhesive, polyurethane adhesive has less odor and storage temperature. It is widely used in construction, furniture, shipbuilding and other fields. At present, the preparation technology of polyurethane adhesive is not specifically adapted to the bonding of pultruded profiles with different matrix resins (epoxy anhydride system and polyurethane system), such as epoxy resin / unsaturated polyester / polyurethane profile bonding using organic fatty acid as release agent.

[0003] Patent CN110283564A discloses a two-component polyurethane adhesive and its preparation method and application. The shear strength between aluminum and aluminum can reach more than 12.5MPa, and the hardness can reach more than 70D of Shore A. It is mainly used for bonding insulation boards, aluminum honeycomb panels, doors and windows, and floors, but does not mention the bonding of composite materials. Patent CN112175572A discloses a method for preparing a high-strength two-component polyurethane adhesive, using vegetable oil polyols to prepare component A of the polyurethane adhesive. This solution meets environmental protection requirements and has good water resistance, weather resistance and low shrinkage. It is suitable for bonding aluminum plates, but does not mention the bonding of composite materials. Patent CN112552863A discloses a solvent-free two-component polyurethane adhesive for structural bonding. The product has the characteristics of high bonding strength, good toughness, and excellent aging resistance. It can be used for structural bonding of composite materials, plastics, metals, etc. It can be used for bonding composite materials without grinding, but does not mention the bonding effect on pultruded profiles. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these purposes and other advantages of the present invention, a two-component polyurethane adhesive for bonding composite materials is provided, comprising component A and component B, wherein the mass ratio of component A to component B is 100:110-120;

[0006] The component A is composed of the following components by weight: 20 to 40 parts of hydroxyl-terminated polyurethane prepolymer, 10 to 30 parts of polyol I, 20 to 35 parts of polyol II, 1 to 1.5 parts of pigment, 0.1 to 0.4 parts of catalyst, 1 to 2 parts of coupling agent, 2 to 5 parts of thixotropic agent, 3 to 8 parts of dewatering agent, and 10 to 20 parts of filler;

[0007] The component B consists of the following components in parts by weight: 30 to 40 parts of isocyanate I, 30 to 50 parts of terminal isocyanate polyurethane prepolymer, 2 to 8 parts of thixotropic agent, and 20 to 30 parts of filler.

[0008] Preferably, the preparation method of the terminal hydroxyl polyurethane prepolymer is as follows: 50 to 70 parts of polyol I and 0.1 to 0.5 parts of catalyst are mixed uniformly by weight, nitrogen is passed through, 20 to 35 parts of isocyanate II are added dropwise, the temperature is raised to 70 to 90° C. under a nitrogen atmosphere, the reaction is carried out for 2 to 4 hours, 5 to 10 parts of a chain extender are added, and the terminal hydroxyl polyurethane prepolymer is obtained after uniform stirring.

[0009] Preferably, the hydroxyl value of the hydroxyl-terminated polyurethane prepolymer is 100 to 250 mg KOH / g.

[0010] Preferably, the preparation method of the isocyanate-terminated polyurethane prepolymer is as follows: 70 to 90 parts of polyol III and 10 to 30 parts of isocyanate II are uniformly mixed by weight, and the mixture is heated to 80 to 90° C. and reacted for 2 to 4 hours under a nitrogen atmosphere to obtain the isocyanate-terminated polyurethane prepolymer.

[0011] Preferably, the isocyanate group (-NCO) content of the isocyanate-terminated polyurethane prepolymer is 2 to 8%.

[0012] Preferably, the polyol I is a difunctional polyether polyol obtained by reacting a small molecule compound having active hydrogen as an initiator with an epoxy compound as a polymerization monomer, and the molecular weight is 200 to 2000; wherein the initiator includes but is not limited to water, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, and dipropylene glycol, and the epoxy compound includes but is not limited to ethylene oxide, ethylene oxide, butylene oxide, and tetrahydrofuran.

[0013] Preferably, the polyol I is one or more of Dexin Federal DDL200, DDL400, DDL600, DDL700, DDL1000D, and DDL2000D.

[0014] Preferably, the polyol II is a trifunctional polyether polyol obtained by reacting a small molecule compound having active hydrogen as an initiator with an epoxy compound as a polymerization monomer, and the molecular weight is 400 to 1000; wherein the initiator includes but is not limited to glycerol, trimethylolpropane, and triethanolamine, and the epoxy compound includes but is not limited to ethylene oxide, ethylene oxide, butylene oxide, and tetrahydrofuran.

[0015] Preferably, the polyol II is one or more of DMN400, DMN450, DMN500, DMN550, DMN700 and DMN1000 produced by Dexin Federation.

[0016] Preferably, the pigment is any one of nano carbon black and ester color paste; the catalyst is an organic tin catalyst or an organic bismuth catalyst; the coupling agent is a silane coupling agent; the thixotropic agent is a solid thixotropic agent, specifically any one of fumed silica and organic bentonite; the dehydrating agent is a solid dehydrating agent, specifically one or two of molecular sieve and calcium oxide; the filler is a powder filler with a particle size less than 40 μm, including but not limited to one or more of calcium silicate, calcium carbonate, silicon micropowder, and talc, and the moisture in the filler is removed by vacuum drying at 150-180° C. for 4-6 hours before use; the chain extender is a glycol chain extender, including but not limited to one or more of ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, and triethylene glycol.

[0017] Preferably, the catalyst is one or more of dibutyltin dilaurate (specific brand such as T-12), stannous octoate (specific brand such as T-9, T-16), dibutyltin mercaptan (specific brand such as T-120), bismuth isooctanoate, bismuth dilaurate, and bismuth neodecanoate.

[0018] Preferably, the coupling agent is one or more of γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, benzylaminomethyltriethoxysilane, benzylaminopropyltriethoxysilane, benzylaminopropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

[0019] Preferably, the isocyanate I is polymeric MDI, specifically one or more of PM-130, PM-200, M20S, 44V20L, MR-200, and PM-400.

[0020] Preferably, the isocyanate II is one or more of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-4,4'-diisocyanate.

[0021] Preferably, the polyol III is one or more of polyester polyol, polycaprolactone polyol, polycarbonate polyol and dimer acid-modified polyester polyol having a molecular weight of 500 to 5000.

[0022] A method for preparing the two-component polyurethane adhesive for bonding composite materials as described above, characterized in that it comprises the following steps:

[0023] Step 1: uniformly mix the terminal hydroxyl polyurethane prepolymer, polyol I and polyol II, dehydrate under reduced pressure for 1 to 3 hours, cool to below 50° C., add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and perform vacuum stirring and high-speed dispersion for 1 to 3 hours to obtain component A; wherein the pressure of dehydration under reduced pressure is ≤150 mbar and the temperature is 110 to 120° C.;

[0024] Step 2: Evenly mix isocyanate I, terminal isocyanate polyurethane prepolymer, thixotropic agent and filler, and prepare component B by vacuum stirring and high-speed dispersion for 1 to 3 hours.

[0025] Preferably, the rotation speed of the high-speed dispersion is 2000-2500 rpm.

[0026] Preferably, when used, components A and B are mixed uniformly according to an isocyanate index R=1.08-1.15.

[0027] The invention discloses an application of the above-mentioned two-component polyurethane adhesive for bonding composite materials in bonding pultruded profiles of epoxy anhydride system, polyurethane system and unsaturated polyester system.

[0028] The present invention includes at least the following beneficial effects: the prepared hydroxyl-terminated polyurethane prepolymer is added to component A and compounded with polyol by the synthesis process of the hydroxyl-terminated polyurethane prepolymer of the present invention, which can provide better weather resistance and adhesion; the two-component polyurethane adhesive for bonding composite materials of the present invention has the advantages of high bonding strength and no need for grinding, and has good bonding effect on pultruded profiles of different matrix resins (epoxy anhydride system, polyurethane system and unsaturated polyester system).

[0029] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The viscosities of component A (A) and component B (B) of Example 3 of the present invention at different shear rates and temperatures. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.

[0033] Example 1

[0034] Preparation of hydroxyl-terminated polyurethane prepolymer:

[0035] 70 parts of polyol I (Dexin Federal DDL400) and 0.2 parts of catalyst (dibutyltin dilaurate, T-12) were mixed evenly by weight, nitrogen was passed through, and 24 parts of isocyanate II (diphenylmethane-4,4'-diisocyanate, Wanhua MDI-100) were added dropwise, the temperature was raised to 80°C under a nitrogen atmosphere for reaction for 3 hours, and 6 parts of chain extender (1,4-butanediol) were added and stirred evenly to obtain a hydroxyl-terminated polyurethane prepolymer 1. The hydroxyl value of the hydroxyl-terminated polyurethane prepolymer 1 tested according to GB / T 12008.3 was 172 mg KOH / g;

[0036] By weight, 60 parts of polyol I (Dexin Federal DDL200) and 0.2 parts of catalyst (dibutyltin dilaurate, T-12) were mixed evenly, nitrogen was passed through, and 35 parts of isocyanate II (diphenylmethane-4,4'-diisocyanate, Wanhua MDI-100) were added dropwise. The temperature was raised to 80°C under a nitrogen atmosphere and reacted for 3 hours. Then 5 parts of chain extender (triethylene glycol) were added and stirred evenly to obtain a terminal hydroxyl polyurethane prepolymer 2. The hydroxyl value of the terminal hydroxyl polyurethane prepolymer 2 tested according to GB / T 12008.3 was 230 mg KOH / g.

[0037] Example 2

[0038] Preparation of isocyanate-terminated polyurethane prepolymers:

[0039] 83 parts of polycaprolactone polyol (Hunan Juren PCL-2000, with a moisture content of less than 0.03%) and 17 parts of toluene diisocyanate (Wanhua TDI-80) were mixed uniformly by weight, and the mixture was heated to 80° C. under a nitrogen atmosphere for reaction for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer 1. The isocyanate group (-NCO) content of the isocyanate-terminated polyurethane prepolymer 1 was 4.65% as determined according to GB / T 12009.4;

[0040] 75 parts of polycaprolactone polyol (Hunan Juren PCL-2000, with a moisture content of less than 0.03%) and 25 parts of toluene diisocyanate (Wanhua TDI-80) were mixed uniformly by weight, and the mixture was heated to 80° C. under a nitrogen atmosphere and reacted for 4 hours to obtain an isocyanate-terminated polyurethane prepolymer 2. The isocyanate group (-NCO) content of the isocyanate-terminated polyurethane prepolymer 2 was 7.81% as determined according to GB / T 12009.4.

[0041] Example 3

[0042] A two-component polyurethane adhesive for bonding composite materials, comprising:

[0043] Component A is composed of the following components by weight: 25 parts of hydroxyl-terminated polyurethane prepolymer 1, 32 parts of polyol II (DMN-500 from Dexin Federation), 22.1 parts of polyol I (DDL-1000D from Dexin Federation), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (bismuth isooctanoate), 1.2 parts of coupling agent (γ-aminopropyltrimethoxysilane), 2.5 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 5 parts of dehydrating agent (molecular sieve), 11 parts of filler (silica powder, particle size ≤10μm);

[0044] Component B is composed of the following components by weight: 34 parts of isocyanate I (BASF M20S), 40 parts of terminal isocyanate polyurethane prepolymer 1, 2 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 24 parts of filler (silicon powder, particle size ≤10μm);

[0045] The preparation method comprises the following steps:

[0046] Step 1: Evenly mix the hydroxyl-terminated polyurethane prepolymer, polyol I and polyol II, and dehydrate them under reduced pressure for 2 hours, cool them to below 50° C., add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and use a double planetary mixer to disperse them at a high speed of 2000 rpm in vacuum for 2 hours to obtain component A; wherein the pressure of dehydration under reduced pressure is ≤100 mbar and the temperature is 115° C.;

[0047] Step 2: uniformly mix isocyanate I, terminal isocyanate polyurethane prepolymer, thixotropic agent and filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm in vacuum for 2 hours to obtain component B;

[0048] The A and B components were evenly mixed in a mass ratio of 100:116 (volume ratio of 1:1, R=1.1) and respectively bonded to epoxy laminate (without release cloth) and polyurethane pultruded board (without release cloth). The substrates were not pretreated such as polishing. They were cured at room temperature for 24 hours and their 0.5mm lap shear strength was tested in accordance with the test method of GB / T33334-2016 "Test method for single lap tensile shear strength of adhesives (composite materials to composite materials)".

[0049] Figure 1 The viscosities of component A and component B of Example 3 at different shear rates and temperatures are shown.

[0050] Example 4

[0051] A two-component polyurethane adhesive for bonding composite materials, comprising:

[0052] Component A is composed of the following components by weight: 28 parts of hydroxyl-terminated polyurethane prepolymer 1, 27 parts of polyol II (DMN-400 from Degussa), 24.1 parts of polyol I (DDL-2000D from Degussa), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (dibutyltin mercaptan, Evonik Chemical T-120), 1.2 parts of coupling agent (γ-aminopropyltriethoxysilane), 2.5 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 5 parts of dehydrating agent (molecular sieve), 11 parts of filler (silica powder, particle size ≤10μm);

[0053] Component B is composed of the following components in parts by weight: 34 parts of isocyanate I (BASF M20S), 40 parts of terminal isocyanate polyurethane prepolymer 1, 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silicon powder, particle size ≤10 μm);

[0054] The preparation method and testing method are the same as those in Example 3.

[0055] Example 5

[0056] A two-component polyurethane adhesive for bonding composite materials, comprising:

[0057] Component A is composed of the following components in parts by weight: 32 parts of hydroxyl-terminated polyurethane prepolymer 2, 30.2 parts of polyol II (DMN-400 from Dexin Federation), 14.4 parts of polyol I (DDL-2000D from Dexin Federation), 1 part of pigment (Kodi Pigment, BK9001-DI), 0.2 parts of catalyst (bismuth isooctanoate), 1.2 parts of coupling agent (γ-glycidyloxypropyltrimethoxysilane), 3 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 3 parts of dehydrating agent (calcium oxide, particle size ≤15μm), 3 parts of dehydrating agent (molecular sieve), 12 parts of filler (silica powder, particle size ≤10μm);

[0058] Component B is composed of the following components in parts by weight: 38 parts of isocyanate I (BASF M20S), 36 parts of isocyanate-terminated polyurethane prepolymer 2, 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silicon powder, particle size ≤10 μm);

[0059] The preparation method and testing method are the same as those in Example 3.

[0060] Example 6

[0061] A two-component polyurethane adhesive for bonding composite materials, comprising:

[0062] Component A is composed of the following components by weight: 26 parts of hydroxyl-terminated polyurethane prepolymer 2, 34 parts of polyol II (DMN-500 from Dexin Federation), 16.6 parts of polyol I (DDL-1000D from Dexin Federation), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (dibutyltin mercaptan, Evonik Chemical T-120), 1.2 parts of coupling agent (γ-aminopropyltriethoxysilane), 3 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 3 parts of dehydrating agent (calcium oxide, particle size ≤15μm), 3 parts of dehydrating agent (molecular sieve), 12 parts of filler (silicon powder, particle size ≤10μm);

[0063] Component B is composed of the following components by weight: 34 parts of isocyanate I (BASF M20S), 40 parts of terminal isocyanate polyurethane prepolymer 2, 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silicon powder, particle size ≤10μm);

[0064] The preparation method and testing method are the same as those in Example 3.

[0065] Example 7

[0066] A two-component polyurethane adhesive for bonding composite materials, comprising:

[0067] Component A is composed of the following components in parts by weight: 27 parts of hydroxyl-terminated polyurethane prepolymer 1, 26.4 parts of polyol II (DMN-400 from Degussa), 22 parts of polyol I (including 14 parts of DDL-1000D from Degussa and 8 parts of DDL-2000D from Degussa), 1.2 parts of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (bismuth isooctanoate), 1.2 parts of coupling agent (N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane), 2 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 3 parts of dewatering agent (calcium oxide, particle size ≤15μm), 5 parts of dewatering agent (molecular sieve), and 12 parts of filler (silica powder, particle size ≤10μm);

[0068] Component B is composed of the following components in parts by weight: 34 parts of isocyanate I (BASF M20S), 40 parts of terminal isocyanate polyurethane prepolymer 1, 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silicon powder, particle size ≤10 μm);

[0069] The preparation method and testing method are the same as those in Example 3.

[0070] Comparative Example 1

[0071] A two-component polyurethane adhesive comprising:

[0072] Component A is composed of the following components by weight: 57 parts of polyol II (DMN-500 from Degussa), 22.1 parts of polyol I (DDL-1000D from Degussa), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (bismuth isooctanoate), 1.2 parts of coupling agent (γ-glycidyloxypropyltrimethoxysilane), 2.5 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 5 parts of dehydrating agent (molecular sieve), 11 parts of filler (silica powder, particle size ≤10um);

[0073] Component B is composed of the following components by weight: 34 parts of isocyanate I (BASF M20S), 40 parts of terminal isocyanate polyurethane prepolymer 1, 2 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 24 parts of filler (silicon powder, particle size ≤10μm);

[0074] The preparation method comprises the following steps:

[0075] Step 1: Mix polyol I and polyol II uniformly and remove water under reduced pressure for 2 hours, cool to below 50°C, add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm in vacuum for 2 hours to obtain component A; wherein the pressure of the reduced pressure dehydration is ≤100 mbar and the temperature is 115°C;

[0076] Step 2: uniformly mix isocyanate I, terminal isocyanate polyurethane prepolymer, thixotropic agent and filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm in vacuum for 2 hours to obtain component B;

[0077] Components A and B were mixed evenly in a mass ratio of 100:78 (volume ratio 1:0.7, R=1.1) and respectively bonded to epoxy laminate (without release cloth) and polyurethane pultruded board (without release cloth). The substrates were not pretreated such as polishing. The mixture was cured at room temperature for 24 hours and its 0.5 mm lap shear strength was tested.

[0078] Comparative Example 2

[0079] A two-component polyurethane adhesive comprising:

[0080] Component A is composed of the following components by weight: 28 parts of hydroxyl-terminated polyurethane prepolymer 1, 27 parts of polyol II (DMN-400 from Degussa), 24.1 parts of polyol I (DDL-2000D from Degussa), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (dibutyltin mercaptan, Evonik Chemical T-120), 1.2 parts of coupling agent (γ-aminopropyltriethoxysilane), 2.5 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 5 parts of dehydrating agent (molecular sieve), 11 parts of filler (silica powder, particle size ≤10μm);

[0081] Component B is composed of the following components by weight: 74 parts of isocyanate I (BASF M20S), 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silica powder, particle size ≤10 μm);

[0082] The preparation method comprises the following steps:

[0083] Step 1: Evenly mix the hydroxyl-terminated polyurethane prepolymer, polyol I and polyol II, and dehydrate them under reduced pressure for 2 hours, cool them to below 50° C., add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and use a double planetary mixer to disperse them at a high speed of 2000 rpm in vacuum for 2 hours to obtain component A; wherein the pressure of dehydration under reduced pressure is ≤100 mbar and the temperature is 115° C.;

[0084] Step 2: uniformly mix the isocyanate I, the thixotropic agent and the filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm for 2 hours in vacuum to obtain component B;

[0085] Components A and B were mixed evenly in a mass ratio of 100:60 (volume ratio 1:0.6, R=1.1) and respectively bonded to epoxy laminate (without release cloth) and polyurethane pultruded board (without release cloth). The substrates were not pretreated such as polishing. The mixture was cured at room temperature for 24 hours and its 0.5mm lap shear strength was tested.

[0086] Comparative Example 3

[0087] A two-component polyurethane adhesive comprising:

[0088] Component A is composed of the following components by weight: 57 parts of polyol II (DMN-500 from Degussa), 22.1 parts of polyol I (DDL-1000D from Degussa), 1 part of pigment (Cody Pigment, BK9001-DI), 0.2 parts of catalyst (bismuth isooctanoate), 1.2 parts of coupling agent (γ-glycidyloxypropyltrimethoxysilane), 2.5 parts of thixotropic agent (Degussa hydrophilic gas silica A200), 5 parts of dehydrating agent (molecular sieve), 11 parts of filler (silica powder, particle size ≤10um);

[0089] Component B is composed of the following components by weight: 74 parts of isocyanate I (BASF M20S), 3 parts of thixotropic agent (Degussa hydrophilic gas silicone A200), and 23 parts of filler (silica powder, particle size ≤10 μm);

[0090] The preparation method comprises the following steps:

[0091] Step 1: Mix polyol I and polyol II uniformly and remove water under reduced pressure for 2 hours, cool to below 50°C, add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm in vacuum for 2 hours to obtain component A; wherein the pressure of the reduced pressure dehydration is ≤100 mbar and the temperature is 115°C;

[0092] Step 2: uniformly mix the isocyanate I, the thixotropic agent and the filler, and use a double planetary mixer to disperse at a high speed of 2000 rpm for 2 hours in vacuum to obtain component B;

[0093] Components A and B were mixed evenly in a mass ratio of 100:150 (volume ratio 1:1.3, R=1.1) and respectively bonded to epoxy laminate (without release cloth) and polyurethane pultruded board (without release cloth). The substrates were not pretreated such as polishing. The mixture was cured at room temperature for 24 hours and its 0.5mm lap shear strength was tested.

[0094] Comparative Example 4

[0095] Sichuan Dongshu New Materials Co., Ltd. epoxy structural adhesive, brand: E240E / E244H, mixing mass ratio of 100:45, the two-component epoxy structural adhesive was mixed evenly and then bonded to epoxy laminate (without release cloth) and polyurethane pultruded board (without release cloth). The substrate was not pretreated such as polishing. After curing at room temperature for 24 hours, it was cured at 70℃ for 6 hours and its 0.5mm lap shear strength was tested.

[0096] As shown in Table 1, for epoxy laminates, the shear strengths of Examples 3 to 7 are all higher than those of Comparative Examples 1 to 4, and the failure modes of the epoxy laminates bonded by the polyurethane adhesives of Examples 3 to 7 are all body failures, while the failure modes of the epoxy laminates bonded by the polyurethane adhesives of Comparative Examples 1 to 4 are all adhesive layer shedding; for polyurethane pultruded sheets, the shear strengths of Examples 3 to 7 are all higher than those of Comparative Example 4, and Comparative Examples 1 to 3 cannot be effectively bonded; By comparing Example 3 with Comparative Example 1, it can be seen that the addition of component A to the hydroxyl-terminated polyurethane prepolymer prepared in Example 1 has It is beneficial to improve the bonding strength of the polyurethane adhesive; by comparing Example 4 and Comparative Example 2, it can be seen that adding component B to the terminal isocyanate polyurethane prepolymer prepared in Example 2 is beneficial to improving the bonding strength of the polyurethane adhesive; in Comparative Example 3, no polyurethane prepolymer is added, and its bonding strength is also lower than that of the embodiment; in summary, it is explained that the two-component polyurethane adhesive for bonding composite materials prepared in Examples 3 to 7 has the advantages of high bonding strength and no need for polishing, and has good bonding effect on pultruded profiles with different matrix resins (epoxy anhydride system and polyurethane system).

[0097] Table 1

[0098]

[0099] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A two-component polyurethane adhesive for bonding composite materials, characterized in that: It comprises component A and component B, wherein the mass ratio of component A to component B is 100:110-120; The component A is composed of the following components by weight: 20 to 40 parts of hydroxyl-terminated polyurethane prepolymer, 10 to 30 parts of polyol I, 20 to 35 parts of polyol II, 1 to 1.5 parts of pigment, 0.1 to 0.4 parts of catalyst, 1 to 2 parts of coupling agent, 2 to 5 parts of thixotropic agent, 3 to 8 parts of dewatering agent, and 10 to 20 parts of filler; The component B consists of the following components in parts by weight: 30 to 40 parts of isocyanate I, 30 to 50 parts of terminal isocyanate polyurethane prepolymer, 2 to 8 parts of thixotropic agent, and 20 to 30 parts of filler.

2. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 1, characterized in that: The preparation method of the terminal hydroxyl polyurethane prepolymer is as follows: 50 to 70 parts of polyol I and 0.1 to 0.5 parts of catalyst are mixed evenly by weight, nitrogen is passed through, 20 to 35 parts of isocyanate II is added dropwise, the temperature is raised to 70 to 90° C. under a nitrogen atmosphere for reaction for 2 to 4 hours, 5 to 10 parts of a chain extender are added, and the terminal hydroxyl polyurethane prepolymer with a hydroxyl value of 100 to 250 mg KOH / g is obtained after evenly stirring.

3. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 2, characterized in that: The preparation method of the isocyanate-terminated polyurethane prepolymer is as follows: 70 to 90 parts of polyol III and 10 to 30 parts of isocyanate II are uniformly mixed by weight, and the mixture is heated to 80 to 90° C. in a nitrogen atmosphere for reaction for 2 to 4 hours to obtain an isocyanate-terminated polyurethane prepolymer having an isocyanate content of 2 to 8%.

4. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 2, characterized in that: The polyol I is a difunctional polyether polyol obtained by reacting a small molecule compound with active hydrogen as an initiator with an epoxy compound as a polymerization monomer, and the molecular weight is 200 to 2000; the polyol II is a trifunctional polyether polyol obtained by reacting a small molecule compound with active hydrogen as an initiator with an epoxy compound as a polymerization monomer, and the molecular weight is 400 to 1000.

5. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 2, characterized in that: The pigment is any one of nano carbon black and ester color paste; the catalyst is an organic tin catalyst or an organic bismuth catalyst; the coupling agent is a silane coupling agent; the thixotropic agent is a solid thixotropic agent, specifically any one of fumed silica and organic bentonite; the dehydrating agent is a solid dehydrating agent, specifically one or two of molecular sieve and calcium oxide; the filler is a powder filler with a particle size less than 40 μm, including but not limited to one or more of calcium silicate, calcium carbonate, silicon micropowder, and talcum powder, and is vacuum dried at 150 to 180° C. for 4 to 6 hours before use to remove moisture in the filler; the chain extender is a glycol chain extender, including but not limited to one or more of ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexanediol, diethylene glycol, and triethylene glycol.

6. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 2, characterized in that: The isocyanate I is polymeric MDI, specifically one or more of PM-130, PM-200, M20S, 44V20L, MR-200, and PM-400.

7. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 3, characterized in that: The isocyanate II is one or more of trimethylene diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, octamethylene diisocyanate, trimethylhexane diisocyanate, tetramethylhexane diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, diphenylmethane-2,4'-diisocyanate, and diphenylmethane-4,4'-diisocyanate.

8. A two-component polyurethane adhesive for bonding composite materials as claimed in claim 3, characterized in that: The polyol III is one or more of polyester polyol, polycaprolactone polyol, polycarbonate polyol and dimer acid-modified polyester polyol having a molecular weight of 500 to 5000.

9. A method for preparing a two-component polyurethane adhesive for bonding composite materials according to any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: Evenly mix the hydroxyl-terminated polyurethane prepolymer, polyol I and polyol II, and dehydrate them under reduced pressure for 1 to 3 hours, cool them to below 50° C., add pigment, catalyst, coupling agent, thixotropic agent, dehydrating agent and filler, and perform vacuum stirring and high-speed dispersion for 1 to 3 hours to obtain component A; wherein the pressure of dehydration under reduced pressure is ≤150 mbar, the temperature is 110 to 120° C., and the speed of high-speed dispersion is 2000 to 2500 rpm; Step 2: Evenly mix isocyanate I, terminal isocyanate polyurethane prepolymer, thixotropic agent and filler, and prepare component B by vacuum stirring and high-speed dispersion for 1 to 3 hours; wherein the rotation speed of high-speed dispersion is 2000 to 2500 rpm.

10. Use of the two-component polyurethane adhesive for bonding composite materials as claimed in any one of claims 1 to 8 in bonding pultruded profiles of epoxy anhydride system, polyurethane system and unsaturated polyester system.

Images