Modified polyurethane flexibilizer, high-toughness and high-stripping modified epoxy resin composition and preparation method of high-toughness and high-stripping modified epoxy resin composition

Abstract

The invention discloses a modified polyurethane flexibilizer, a high-toughness and high-stripping modified epoxy resin composition and a preparation method thereof. The composition is prepared from the following components in parts by weight: 15 to 30 parts of modified polyurethane flexibilizer, 20 to 45 parts of epoxy resin, 8 to 20 parts of core-shell flexibilizer, 8 to 20 parts of filler, 4 to 10 parts of curing agent and 0.2 to 1.5 parts of coupling agent. Wherein the modified polyurethane toughening agent is prepared from the following raw materials in parts by weight: 60 to 90 parts of reactive polyol compound, 6 to 15 parts of polyisocyanate, 4 to 15 parts of micromolecular acrylate containing reactive hydrogen, 0.2 to 3 parts of chain extender and 0.02 to 0.2 part of catalyst. The prepared single-component epoxy composition has the properties of high toughness, high stripping performance, low-temperature curing, high strength retention rate after high and low temperature circulation and the like, and is suitable for being applied to component assembly in the fields of rail transit, aviation and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a modified polyurethane toughening agent, a high-toughness and high-peeling modified epoxy resin composition and a preparation method thereof. Background Art

[0002] Today, the rail transit and aviation fields are booming at an unprecedented speed, driving a substantial increase in the demand for various new materials. In the connection process of advanced materials, the bonding demand between different materials has become increasingly significant. Especially in the processing and assembly of high-performance non-metallic materials such as high-strength aluminum alloys and carbon fibers, there is an urgent need for high-strength structural adhesives that can provide reliable connections.

[0003] Due to its excellent mechanical properties, bonding properties, chemical corrosion resistance, and dimensional stability, epoxy resin has been widely used in many fields such as aerospace, automotive manufacturing, electronic packaging, and construction. However, traditional epoxy resins usually have a relatively high crosslinking density, resulting in relatively low toughness and peeling strength.

[0004] Considering the complex working conditions faced by locomotives and aircraft during actual operation, long-term vibration and bumping, and the impact force generated by frequent speed conversions during high-speed operation. Therefore, how to develop a structural adhesive that can connect different materials, has high toughness and high peeling strength, can significantly enhance the vibration fatigue resistance of the entire carriage components, and ensure the integrity and safety of the structure under long-term dynamic load is an urgent problem to be solved.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a modified polyurethane toughening agent, a high-toughness and high-peeling modified epoxy resin composition and a preparation method thereof, which can withstand long-term vibration fatigue under different working conditions, ensure the integrity and safety of the structure under long-term dynamic load, and thus solve the above technical problems existing in the prior art.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A modified polyurethane toughening agent, comprising the following raw materials in parts by weight:

[0009] 60 - 90 parts of a reactive polyol compound, 6 - 15 parts of a polyisocyanate, 4 - 15 parts of a small molecule acrylate containing active hydrogen, 0.2 - 3 parts of a chain extender, and 0.02 - 0.2 parts of a catalyst.

[0010] Preferably, among the above toughening agents, the reactive polyol compound is at least one of polyether polyol, polyester polyol, polycarbonate polyol, polyacrylate polyol, and polyhydrocarbon polyol;

[0011] The small molecule acrylate containing active hydrogen is at least one of acrylate containing hydroxyl group and acrylate containing secondary amino group;

[0012] Preferably, among the above toughening agents, the polyisocyanate is diisocyanate;

[0013] The chain extender is small molecule diol;

[0014] The catalyst is an organic tin catalyst or an organic titanium catalyst.

[0015] Preferably, among the above toughening agents, the polyisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate;

[0016] The small molecule diol is at least one of ethylene glycol, propylene glycol, and butanediol;

[0017] The catalyst is one of bis(dodecylthio) dibutyltin, dibutyltin diacetate, dialkyltin dimaleate, dithioglycol alkyltin, 4-isopropoxytitanium, and diethyleneglycol titanate.

[0018] A preparation method of the modified polyurethane toughening agent described in the present invention includes:

[0019] Take each raw material according to the formula of the modified polyurethane toughening agent described in the present invention;

[0020] Step 1: Add the reactive polyol compound in the raw materials into a reaction kettle, heat it to above 50°C, and under nitrogen protection, add polyisocyanate, and mix and stir for more than 15 minutes to make the two evenly mixed;

[0021] Step 2: After stirring and mixing evenly, add the catalyst, and stir and keep the temperature at 60-90°C for 2-4 hours until the NCO% is qualified;

[0022] Step 3: Add the small molecule acrylate containing active hydrogen, control the temperature at 70-80°C for reaction for 3-6 hours, and after testing that the NCO% is qualified, cool it to below 70°C, add the chain extender, and stir and react under vacuum for 4-6 hours or until the NCO% is 0 and then stop the reaction;

[0023] Step 4: Carry out vacuum distillation on the obtained product to remove low-boiling substances, and the remaining product is the modified polyurethane toughening agent.

[0024] A high-toughness and high-peel modified epoxy resin composition, which is composed of the following components in parts by weight:

[0025] 15 - 30 parts of the modified polyurethane toughening agent described in the present invention, 20 - 45 parts of epoxy resin, 8 - 20 parts of core-shell toughening agent, 8 - 20 parts of filler, 4 - 10 parts of curing agent, and 0.2 - 1.5 parts of coupling agent.

[0026] Preferably, in the above composition, the epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, acrylic acid-modified epoxy resin, and other modified epoxy resins;

[0027] The core-shell toughening agent is one or more of hydroxyl-terminated polybutadiene, butadiene-styrene block copolymer, and liquid nitrile rubber.

[0028] Preferably, in the above composition, the curing agent is at least two combinations of dicyandiamide, modified imidazole, substituted urea curing agent, and modified amine curing agent;

[0029] The filler is one or more of silica powder, calcium carbonate, aluminum hydroxide, alumina, talc powder, and nano-calcium.

[0030] Preferably, the above composition further includes: 0.1 - 2 parts by weight of dispersant.

[0031] A preparation method for the high-toughness and high-peel modified epoxy resin combination described in the present invention, including:

[0032] Take each raw material according to the formula of the high-toughness and high-peel modified epoxy resin combination described in the present invention;

[0033] Step 21, add the modified polyurethane toughening agent, epoxy resin, and core-shell toughening agent described in the present invention in the raw materials to the reaction kettle, and stir at a high speed of 30 - 50 r / min for 0.5 h until evenly dispersed, and keep the vacuum degree at -0.85 to -0.1 Mpa;

[0034] Step 22, add the dispersant and coupling agent to the reaction kettle, keep the vacuum degree at -0.085 to -0.1 MPa, and disperse at a high speed of 30 - 50 r / min for 0.5 h until evenly dispersed;

[0035] Step 23, add the curing agent to the reaction kettle, keep the vacuum degree at -0.085 to -0.01 MPa, and stir at a high speed of 30 - 50 r / min for 0.5 - 1 h until evenly dispersed.

[0036] Step 24: Add fillers into the reactor, maintain the vacuum degree at -0.085 to -0.01 MPa, stir at a high speed of 30 to 50 r / min for 1 to 3 h, then change to a low speed of 5 to 15 r / min and stir while maintaining the vacuum degree within the range of -0.095 to -0.01 MPa for 1 h, and extract the bubbles. The obtained product is the high-toughness and high-peel-modified epoxy resin combination.

[0037] Compared with the prior art, the modified polyurethane toughening agent, the high-toughness and high-peel-modified epoxy resin composition and the preparation method thereof provided by the present invention have the following beneficial effects:

[0038] By combining a reactive polyol compound, a polyisocyanate, a small molecule acrylate containing active hydrogen, a chain extender and a catalyst in a specific ratio, a modified polyurethane toughening agent with a high degree of crosslinking and containing active groups is synthesized. This modified polyurethane toughening agent has the characteristics of high strength, and at the same time, it also has good compatibility with the core-shell toughening agent and epoxy resin, especially has the characteristics of high toughness and high bonding strength. The modified epoxy resin composition prepared with this modified polyurethane toughening agent has a high elongation at break, a high peel strength, and a relatively high bonding strength. After high and low temperature aging, it still maintains good bonding ability, can effectively resist external force impact and peel stress, and reduce the occurrence of cracking and debonding phenomena. At the same time, the raw materials of this composition are easy to obtain, the preparation process is simple, and it is suitable for large-scale industrial production. Through reasonable process control, it can ensure the uniform dispersion of each component and the stable and reliable product quality. Specific embodiments

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the specific content of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, which do not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0040] First, the following explanations are given for the terms that may be used in this article:

[0041] The term "and / or" means that either one or both of the two can be achieved. For example, X and / or Y means that it includes both the case of "X" or "Y" and the three cases of "X and Y".

[0042] Descriptions using terms such as "comprising", "including", "containing", "having" or other similar semantics shall be construed as non-exclusive inclusion. For example, including a technical feature element (such as raw material, component, ingredient, carrier, dosage form, material, size, part, component, mechanism, device, step, process, method, reaction condition, processing condition, parameter, algorithm, signal, data, product or article, etc.) shall be construed as not only including the explicitly listed technical feature element, but also including other technical feature elements well-known in the art that are not explicitly listed.

[0043] The term "consisting of" means excluding any technical feature element that is not explicitly listed. If this term is used in a claim, it will make the claim a closed type, so that it does not include technical feature elements other than the explicitly listed ones, except for conventional impurities related thereto. If this term only appears in a sub-clause of a claim, then it only limits the elements explicitly listed in that sub-clause, and the elements recorded in other sub-clauses are not excluded from the overall claim.

[0044] The term "parts by mass" represents the mass ratio relationship between multiple components. For example, if component X is x parts by mass and component Y is y parts by mass, it means the mass ratio of component X to component Y is x:y; 1 part by mass can represent any mass, for example: 1 part by mass can be represented as 1 kg or 3.1415926 kg, etc. The sum of the parts by mass of all components is not necessarily 100 parts, and it can be greater than 100 parts, less than 100 parts or equal to 100 parts. Unless otherwise specified, the parts, ratios and percentages described herein are by mass.

[0045] When a concentration, temperature, pressure, size or other parameter is expressed in the form of a numerical range, this numerical range should be understood as specifically disclosing all ranges formed by the pairing of any upper limit value, lower limit value, and preferred value within this numerical range, regardless of whether this range is explicitly recorded; for example, if the numerical range "2 to 8" is recorded, then this numerical range should be construed as including ranges such as "2 to 7", "2 to 6", "5 to 7", "3 to 4 and 6 to 7", "3 to 5 and 7", "2 and 5 to 7", etc. Unless otherwise specified, the numerical ranges recorded herein include both their end values and all integers and fractions within this numerical range.

[0046] The solutions provided by the present invention are described in detail below. The content not described in detail in the embodiments of the present invention belongs to the prior art well-known to those skilled in the art. For those conditions not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the art or the conditions recommended by the manufacturer. For the reagents or instruments not indicating the manufacturer in the embodiments of the present invention, they are all conventional products that can be obtained by purchasing in the market.

[0047] An embodiment of the present invention provides a modified polyurethane toughening agent, which is composed of the following components by weight: 60-90 parts of a reactive polyol compound, 6-15 parts of a polyisocyanate, 4-15 parts of a small molecule acrylate containing active hydrogen, 0.2-3 parts of a chain extender, and 0.02-0.2 parts of a catalyst.

[0048] Preferably, in the above toughening agent, the reactive polyol compound is at least one of a polyether polyol, a polyester polyol, a polycarbonate polyol, a polyacrylate polyol, and a polyhydrocarbon polyol; the reactive polyol compound is preferably a polyether polyol or a polyester polyol.

[0049] Preferably, in the above toughening agent, the polyisocyanate is a diisocyanate, such as at least one of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), and isophorone diisocyanate (IPDI).

[0050] Preferably, in the above toughening agent, the small molecule acrylate containing active hydrogen mainly adopts at least one of an acrylate containing a hydroxyl group and an acrylate containing a secondary amino group.

[0051] Preferably, in the above toughening agent, the chain extender adopts a small molecule diol, such as at least one of ethylene glycol, propylene glycol, and butanediol.

[0052] Preferably, in the above toughening agent, the catalyst adopts an organotin catalyst or an organotitanium catalyst, preferably at least one of dibutyltin dilaurate, dibutyltin diacetate, dialkyltin dimaleate, dithioldialkyltin, 4-isopropoxytitanium, and diethyleneglycol titanate.

[0053] The preparation process of the above modified polyurethane toughening agent includes:

[0054] First, take each raw material according to the formula of the modified polyurethane toughening agent;

[0055] Step 1: Add the reactive polyol compound in the raw materials to a reaction kettle, heat it to above 50°C, and under nitrogen protection, add the polyisocyanate, and mix and stir for more than 15 minutes to ensure uniform mixing;

[0056] Step 2: After stirring evenly, add the catalyst, and stir and keep warm at 60-90°C for 2-4 hours until the NCO% is qualified;

[0057] Step 3: Add the small molecule acrylate containing active hydrogen to the reaction kettle, continue to control the temperature at 70°C-80°C and react for 3-6 hours. After testing that the NCO% is qualified, cool it to below 70°C, and continue to add a small molecule chain extender such as diol, and stir and react under vacuum for 4-6 hours, or stop the reaction until the NCO% is 0.

[0058] Step 4: Subject the obtained product to vacuum distillation to remove low-boiling substances. The remaining product is the prepared modified polyurethane toughening agent.

[0059] The embodiment of the present invention also provides a high-toughness and high-peel modified epoxy resin composition prepared using the above-mentioned modified polyurethane toughening agent, which is composed of the following components by weight:

[0060] 15 - 30 parts of the above-mentioned modified polyurethane toughening agent, 20 - 45 parts of epoxy resin, 8 - 20 parts of core-shell toughening agent, 8 - 20 parts of filler, 4 - 10 parts of curing agent, and 0.2 - 1.5 parts of coupling agent;

[0061] Further, it may also include 0.1 - 2 parts of dispersant.

[0062] Preferably, in the above composition, the epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, acrylic acid-modified epoxy resin, and other modified epoxy resins.

[0063] Preferably, in the above composition, the core-shell toughening agent is one or several of hydroxyl-terminated polybutadiene, butadiene-styrene block copolymer, and liquid nitrile rubber.

[0064] Preferably, in the above composition, the curing agent is at least two combinations of dicyandiamide, modified imidazole, substituted urea-based, and modified amine-based latent curing agents.

[0065] Preferably, in the above composition, the filler is one or more of silica powder, fumed silica, calcium carbonate, aluminum hydroxide, alumina, talc powder, and glass microspheres.

[0066] The preparation process of the above-mentioned one-component high-toughness and high-peel modified epoxy resin composition includes:

[0067] First, take each raw material according to the formula of the modified epoxy resin composition;

[0068] Step 21: Add the modified polyurethane toughening agent, epoxy resin, and core-shell toughening agent described in any one of claims 1 - 4 in the raw materials to the reaction kettle, and stir at a high speed of 30 - 50 r / min for 0.5 h until evenly dispersed, and keep the vacuum degree at -0.85 to -0.1 Mpa;

[0069] Step 22: Add the dispersant and coupling agent to the reaction kettle, keep the vacuum degree at -0.085 to -0.1 MPa, and disperse at a high speed of 30 - 50 r / min for 0.5 h until evenly dispersed;

[0070] Step 23: Add a curing agent to the reaction kettle, maintain the vacuum degree at -0.085 to -0.01 MPa, and stir at a high speed of 30 to 50 r / min for 0.5 to 1 h until evenly dispersed.

[0071] Step 24: Add a filler to the reaction kettle, maintain the vacuum degree at -0.085 to -0.01 MPa, stir at a high speed of 30 to 50 r / min for 1 to 3 h, then change to a low speed of 5 to 15 r / min and stir, maintain the vacuum degree within the range of -0.095 to -0.01 MPa and stir for 1 h to extract the bubbles. The resulting product is a high-toughness and high-peel modified epoxy resin combination.

[0072] In summary, for the composition of the embodiment of the present invention, by using a modified polyurethane toughening agent with high toughness and high bonding strength to prepare the modified epoxy resin composition, the obtained product has a high elongation at break, a high peel strength, and a relatively high bonding strength. After high and low temperature aging, it still maintains good bonding ability, can effectively resist external force impact and peel stress, and reduce the occurrence of cracking and debonding phenomena. At the same time, the raw materials of this composition are easily available, the preparation process is simple, and it is suitable for large-scale industrial production. Through reasonable process control, it can ensure the uniform dispersion of each component, and the product quality is stable and reliable.

[0073] In order to more clearly show the technical solutions provided by the present invention and the technical effects produced, the following uses specific examples to describe in detail the solutions provided by the embodiments of the present invention.

[0074] Example 1

[0075] This example provides a high-toughness and high-peel modified epoxy resin composition, and its preparation method includes (each raw material is in parts by weight):

[0076] (1) First, prepare a modified polyurethane toughening agent:

[0077] 1) Add 80 parts of polyether polyol with a molecular weight of 2000 to the reaction kettle, heat up to above 50 °C, and under nitrogen protection, add 11 parts of MDI, and mix and stir for more than 15 min to ensure uniform mixing;

[0078] 2) After stirring evenly, add 0.02 part of dibutyltin dilaurate as a catalyst, and stir and keep warm at 60 to 90 °C for 2 to 4 h until the NCO% value is 0.9%;

[0079] 3) Add 7 parts of hydroxyethyl acrylate, continue to control the temperature at 70 °C to 80 °C and react for 3 to 6 h, and test that the NCO% is reduced to 0.2%. Cool down to below 70 °C, and continue to add 1,4-butanediol as a chain extender, stir and react under vacuum for 4 to 6 h or stop the reaction until the NCO% is 0;

[0080] 4) Carry out reduced-pressure distillation on the obtained product to remove low-boiling substances, and the remaining product is the prepared modified polyurethane toughening agent for standby.

[0081] (II) Preparation of modified epoxy resin composition:

[0082] 21) Add 28 parts of the above-prepared modified polyurethane toughening agent, 40 parts of bisphenol A epoxy resin WSR618, and 13 parts of core-shell rubber to the reaction kettle, and stir for 0.5 h until evenly dispersed, with the vacuum degree maintained at -0.85 to -0.1 Mpa;

[0083] 22) Add 0.4 part of dispersant and 0.6 part of coupling agent, keep the vacuum degree between -0.085 and -0.1 MPa, and disperse at high speed for 0.5 h until evenly dispersed;

[0084] 23) Add 6.4 parts of curing agent dicyandiamide and 0.6 part of substituted urea, keep the vacuum degree at -0.085 to -0.01 Mpa, and stir at high speed for 0.5 - 1 h until evenly dispersed.

[0085] 24) Add 3 parts of calcium oxide, 4 parts of fumed silica, and 5 parts of wollastonite, keep the vacuum degree at -0.085 to -0.01 Mpa, stir at high speed for 1 - 3 h, then change to low-speed stirring, keep the vacuum degree in the range of -0.095 to -0.01 Mpa and stir for 1 h to extract the bubbles. The obtained product is the high-toughness and high-peel modified epoxy resin composition.

[0086] Example 2

[0087] This example provides a high-toughness and high-peel modified epoxy resin composition, and its preparation method includes (each raw material is in parts by weight):

[0088] (I) First, prepare the modified polyurethane toughening agent:

[0089] 1) Add 80 parts of polyether polyol with a molecular weight of 2000 to the reaction kettle, heat up to above 50 °C, and under nitrogen protection, add 11 parts of MDI, and mix and stir for more than 15 min to ensure uniform mixing;

[0090] 2) After stirring evenly, add 0.02 part of catalyst dibutyltin dilaurate, and stir and keep warm at 60 - 90 °C for 2 - 4 h until the NCO% value is 0.9%;

[0091] 3) Add 7 parts of hydroxyethyl acrylate, continue to control the temperature at 70 °C - 80 °C and react for 3 - 6 h, and test that the NCO% is reduced to 0.2%, cool down to below 70 °C, and continue to add 1,4-butanediol as a chain extender, stir and react under vacuum for 4 - 6 h or until the reaction stops when the NCO% is 0;

[0092] 4) Subject the obtained product to vacuum distillation to remove low-boiling substances, and the remaining product is the modified polyurethane toughening agent for standby.

[0093] (II) Preparation of the modified epoxy resin composition:

[0094] 21) Add 23 parts of the above-prepared modified polyurethane toughening agent, 40 parts of bisphenol A epoxy resin WSR618, and 18 parts of core-shell rubber to the reaction kettle, and stir for 0.5 h until evenly dispersed, with the vacuum degree maintained at -0.85 to -0.1 Mpa;

[0095] 22) Add 0.4 part of dispersant and 0.6 part of coupling agent, maintain the vacuum degree between -0.085 and -0.1 MPa, and disperse at high speed for 0.5 h until evenly dispersed;

[0096] 23) Add 6.4 parts of dicyandiamide as curing agent and 0.6 part of substituted urea, maintain the vacuum degree at -0.085 to -0.01 MPa, and stir at high speed for 0.5 - 1 h until evenly dispersed.

[0097] 24) Add 3 parts of calcium oxide, 4 parts of fumed silica, and 5 parts of wollastonite, maintain the vacuum degree at -0.085 to -0.01 MPa, stir at high speed for 1 - 3 h, then change to low-speed stirring, maintain the vacuum degree in the range of -0.095 to -0.01 MPa and stir for 1 h to extract the bubbles, and the obtained product is the high-toughness and high-peel modified epoxy resin composition.

[0098] Example 3

[0099] This example provides a high-toughness and high-peel modified epoxy resin composition, and its preparation method includes (each raw material is in parts by weight):

[0100] (I) First, prepare the modified polyurethane toughening agent:

[0101] 1) Add 80 parts of polyester polyol with a molecular weight of 2000 to the reaction kettle, heat up to above 50 °C, and under nitrogen protection, add 11 parts of MDI, and mix and stir for more than 15 min to ensure uniform mixing;

[0102] 2) After stirring evenly, add 0.02 part of dibutyltin dilaurate as catalyst, and stir and keep the temperature at 60 - 90 °C for 2 - 4 h until the NCO% value reaches 0.9%;

[0103] 3) Add 7 parts of hydroxyethyl acrylate, continue to control the temperature at 70 °C - 80 °C and react for 3 - 6 h, and test that the NCO% decreases to 0.2%, cool down to below 70 °C, and continue to add 1,4-butanediol as chain extender, stir and react under vacuum for 4 - 6 h or stop the reaction until the NCO% is 0;

[0104] 4) Subject the obtained product to vacuum distillation to remove low-boiling substances. The remaining product is the modified polyurethane toughening agent and is reserved for use.

[0105] (II) Preparation of the modified epoxy resin composition:

[0106] 21) Add 28 parts of the above-prepared modified polyurethane toughening agent, 40 parts of bisphenol A epoxy resin WSR618, and 13 parts of core-shell rubber to the reaction kettle, and stir for 0.5 h until uniformly dispersed. Keep the vacuum degree at -0.85 to -0.1 Mpa.

[0107] 22) Add 0.4 part of dispersant and 0.6 part of coupling agent. Keep the vacuum degree between -0.085 and -0.1 MPa, and disperse at high speed for 0.5 h until uniformly dispersed.

[0108] 23) Add 6.4 parts of curing agent dicyandiamide and 0.6 part of substituted urea, and keep the vacuum degree at -0.085 to -0.01 MPa and stir at high speed for 0.5 - 1 h until uniformly dispersed.

[0109] 24) Add 3 parts of calcium oxide, 4 parts of fumed silica, and 5 parts of wollastonite. Keep the vacuum degree at -0.085 to -0.01 MPa and stir at high speed for 1 - 3 h, then change to low-speed stirring. Keep the vacuum degree in the range of -0.095 to -0.01 MPa and stir for 1 h to extract the bubbles. The obtained product is the high-toughness and high-peel modified epoxy resin composition.

[0110] Example 4

[0111] This example provides a high-toughness and high-peel modified epoxy resin composition, and its preparation method includes (each raw material is in parts by weight):

[0112] (I) First, prepare the modified polyurethane toughening agent:

[0113] 1) Add 80 parts of polyether polyol with a molecular weight of 2000 to the reaction kettle and heat up to above 50 °C. Under nitrogen protection, add 11 parts of MDI, and mix and stir for more than 15 min to ensure uniform mixing.

[0114] 2) After stirring evenly, add 0.02 part of catalyst dibutyltin dilaurate, and stir and keep warm at 60 - 90 °C for 2 - 4 h until the NCO% value is 0.9%.

[0115] 3) Add 5 parts of hydroxyethyl acrylate, continue to control the temperature at 70 °C - 80 °C and react for 3 - 6 h, and test that the NCO% is reduced to 0.25%. Cool down to below 70 °C, and continue to add 1,4-butanediol as a chain extender, and stir and react under vacuum for 4 - 6 h or stop the reaction until the NCO% is 0.

[0116] 4) Subject the obtained product to vacuum distillation to remove low-boiling substances. The remaining product is the self-made modified polyurethane toughening agent, which is reserved for use.

[0117] (II) Preparation of modified epoxy resin composition:

[0118] 21) Add 28 parts of the self-made modified polyurethane toughening agent, 40 parts of bisphenol A epoxy resin WSR618, and 13 parts of core-shell rubber to the reaction kettle, and stir for 0.5 h until evenly dispersed. Keep the vacuum degree at -0.85 to -0.1 Mpa.

[0119] 22) Add 0.4 part of dispersant and 0.6 part of coupling agent. Keep the vacuum degree between -0.085 and -0.1 MPa, and disperse at high speed for 0.5 h until evenly dispersed.

[0120] 23) Add 6.4 parts of curing agent dicyandiamide and 0.6 part of substituted urea, and keep the vacuum degree at -0.085 to -0.01 Mpa. Stir at high speed for 0.5 - 1 h until evenly dispersed.

[0121] 24) Add 3 parts of calcium oxide, 4 parts of fumed silica, and 5 parts of wollastonite. Keep the vacuum degree at -0.085 to -0.01 Mpa and stir at high speed for 1 - 3 h, then change to low-speed stirring. Keep the vacuum degree in the range of -0.095 to -0.01 Mpa and stir for 1 h to remove bubbles. The obtained product is the high-toughness and high-peel modified epoxy resin composition.

[0122] The test methods involved in the present invention are as follows:

[0123] After preparing the sample, bake it at 170 °C for 20 min and then test.

[0124] Elongation at break: Prepare the sample with reference to ISO 527-1, and use a tensile testing machine to test and record the elongation at break.

[0125] Peel strength: Prepare the sample with reference to the T peel strength test method for adhesives in GB / T 2791, and use a tensile testing machine to test.

[0126] Shear strength: Prepare the sample with reference to the test method for tensile shear strength of adhesives in GB / T 7124, and use a tensile testing machine to test.

[0127] Shear strength test after aging: Test with reference to the standard for high and low temperature test cycles in GB / T 2423. After 60 cycles, test the shear strength.

[0128] After testing, the test results of each example and a certain foreign product purchased on the market are as follows:

[0129] Table 1 shows the test results of each example.

[0130] Example 1 Example 2 Example 3 Example 4 Foreign products Peel strength (N / mm) 12.2 9.5 13.2 10.2 8 Elongation rate % 12 9 15 14 5 Shear strength (MPa) 32.4 31.2 33 33.6 28.8 Shear strength after aging (MPa) 31.5 29.3 32.2 32.1 27.6

[0131] From the above test results, it can be seen that the one-component modified epoxy resin composition prepared by the present invention has high toughness, high peel strength, relatively high strength, and a relatively high strength retention rate after aging. It can be applied to the component assembly in the rail transit and aviation fields, and can effectively resist external force impact and peel stress, reducing the occurrence of cracking and debonding phenomena.

[0132] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background art of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art known to those skilled in the art.

Claims

1. A modified polyurethane toughening agent, characterized in that: The invention comprises the following raw materials in parts by weight: 60-90 parts of reactive polyol compound, 6-15 parts of polyisocyanate, 4-15 parts of small molecule acrylate containing active hydrogen, 0.2-3 parts of chain extender and 0.02-0.2 parts of catalyst.

2. The modified polyurethane toughening agent according to claim 1, characterized in that: The reactive polyol compound is at least one of polyether polyol, polyester polyol, polycarbonate polyol, polyacrylate polyol and polyhydrocarbon polyol; The small molecule acrylate containing active hydrogen is at least one of acrylate containing hydroxyl group and acrylate containing secondary amine group.

3. The modified polyurethane toughening agent according to claim 1 or 2, characterized in that: The polyisocyanate is diisocyanate; The chain extender is a small molecule diol; The catalyst is an organic tin catalyst or an organic titanium catalyst.

4. The modified polyurethane toughening agent according to claim 3, characterized in that: The polyisocyanate is at least one of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate and isophorone diisocyanate; The small molecule diol is at least one of ethylene glycol, propylene glycol and butanediol; The catalyst is one of didodecylsulfide dibutyltin, dibutyltin diacetate, dialkyltin dimaleate, dithioalkyltin, 4-isopropoxytitanium and diethylene glycol titanate.

5. A method for preparing the modified polyurethane toughening agent according to any one of claims 1 to 4, characterized in that: include: Take the raw materials according to the formula of the modified polyurethane toughening agent according to any one of claims 1 to 4; Step 1, add the reactive polyol compound in the raw material into a reaction kettle and heat it to above 50° C., add polyisocyanate under nitrogen protection, mix and stir for more than 15 minutes to make the two mixed evenly; Step 2, after stirring and mixing evenly, add the catalyst, stir and keep warm at 60-90° C. for 2-4 hours until the NCO% reaches the required level; Step 3, add a small molecule acrylate containing active hydrogen, control the temperature to 70°C to 80°C for reaction for 3 to 6 hours, and after the NCO% is tested to be qualified, cool to below 70°C, add a chain extender, stir and react in vacuum for 4 to 6 hours or stop the reaction when the NCO% is 0; Step 4, distilling the obtained product under reduced pressure to remove low-boiling point substances, and the remaining product is the modified polyurethane toughening agent.

6. A high-toughness and high-peeling modified epoxy resin composition, characterized in that: It is composed of the following components in parts by weight: 15-30 parts of the modified polyurethane toughening agent according to any one of claims 1 to 4, 20-45 parts of epoxy resin, 8-20 parts of core-shell toughening agent, 8-20 parts of filler, 4-10 parts of curing agent and 0.2-1.5 parts of coupling agent.

7. The high-toughness and high-peeling modified epoxy resin composition according to claim 6, characterized in that: The epoxy resin is one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, acrylic modified epoxy resin, and other modified epoxy resins; The core-shell toughening agent is one or more of terminal hydroxyl polybutadiene, butadiene-styrene block copolymer and liquid nitrile rubber.

8. The high-toughness and high-peeling modified epoxy resin composition according to claim 6, characterized in that: The curing agent is a combination of at least two of dicyandiamide, modified imidazole, substituted urea curing agent, and modified amine curing agent; The filler is one or more of silicon micropowder, calcium carbonate, aluminum hydroxide, aluminum oxide, talcum powder, and nano calcium.

9. The high-toughness and high-peeling modified epoxy resin composition according to any one of claims 6 to 8, characterized in that: Also includes: Dispersant 0.1 to 2 parts by weight.

10. A method for preparing the high-toughness and high-peeling modified epoxy resin combination according to any one of claims 6 to 9, characterized in that: include: Take the raw materials according to the formula of the high-toughness and high-peeling modified epoxy resin combination described in any one of claims 6 to 9; Step 21, adding the modified polyurethane toughening agent, epoxy resin and core-shell toughening agent described in any one of claims 1 to 4 in the raw materials into the reaction kettle, stirring at a speed of 30 to 50 r / min for 0.5 h until the mixture is evenly dispersed, and maintaining the vacuum degree at -0.85 to -0.1 MPa; Step 22, adding a dispersant and a coupling agent to the reactor, maintaining a vacuum degree of -0.085 to -0.1 MPa, and dispersing at a speed of 30 to 50 r / min for 0.5 h until the mixture is uniformly dispersed; Step 23, adding curing agent into the reaction kettle, maintaining the vacuum degree at -0.085 to -0.01 MPa and stirring at a speed of 30 to 50 r / min for 0.5 to 1 h until the mixture is evenly dispersed. Step 24, add filler to the reactor, maintain the vacuum degree at -0.085 to -0.01 MPa, stir at a high speed of 30 to 50 r / min for 1 to 3 hours, then change to low speed stirring of 5 to 15 r / min, maintain the vacuum degree in the range of -0.095 to -0.01 MPa, stir for 1 hour, extract the bubbles, and the obtained product is a high-toughness and high-peeling modified epoxy resin combination.