Modified polyurethane resin, modified thermosetting resin and preparation method thereof

Abstract

The invention discloses a modified polyurethane resin, a modified thermosetting resin and a preparation method thereof, and the preparation method comprises the following steps: step 1, carrying out degradation reaction on initial polyurethane and a degradation agent with an active group to break at least one part of molecular chains of the initial polyurethane, preparing a resin intermediate containing a molecular fragment with initial polyurethane and the active group; 3, the resin intermediate reacts with a grafting agent with a grafting group, and modified polyurethane resin containing an initial polymer molecular chain segment with a chain extension group is prepared; the grafting reaction comprises one or a combination of more of an esterification reaction, an acylation reaction, an amide condensation reaction or an ester exchange reaction; the grafting group is selected from one or more of amido, ureido, hydroxyl, carboxyl, ester group, anhydride or epoxy group.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a modified polyurethane resin, a modified thermosetting resin and a preparation method thereof. Background Art

[0002] Alcohol hydrolysis recovery of polyurethane solid materials is one of the most commonly used chemical recycling methods for polyurethane degradation and recycling. Polyurethane solid materials include polyurethane solid waste, scraps generated during the production of polyurethane products, retired polyurethane materials (refrigerator container insulation rigid foam, mattress sofa soft foam, sole materials, polyurethane elastomers, polyurethane semi-rigid foam, polyurethane adhesives, etc.) and polyurethane composite materials (window frames, beams, solar frames, sleepers, cable boxes, battery shells, sucker rods, brackets, etc.) and other solid alcoholysis.

[0003] However, the alcoholysis of these solid polyurethanes, including alcoholysis of various polyurethane solid wastes (soft foam, hard foam, semi-hard foam, elastomer, adhesive, casting body, composite material, etc.), is conventionally recycled by purifying the polyol products obtained by polyurethane degradation and then mixing them back in a certain proportion in common polyol (i.e., conventional industrial polyol obtained by ring opening of ethylene oxide, propane or butane, or polyester polyol, etc.) components to re-prepare various polyurethane products, such as foam, elastomer, adhesive, etc., without further research and utilization. This recycling method is limited to the polyol component and does not involve other components, so its economic value is limited, and its use is also limited, which is not conducive to the efficient recycling of polyurethane solid waste.

[0004] Various commonly used thermosetting resins have very wide application scenarios in our daily lives. They usually have the advantage of high strength, but are accompanied by the disadvantages of low toughness and brittleness. Therefore, how to retain the high strength of thermosetting resins but overcome their poor toughness has always been an important demand. For example, epoxy resin has high strength but poor toughness, and is a high-strength thermosetting resin with greater brittleness. Therefore, the toughening of epoxy resin has always been one of the most urgent needs in its application field. In addition to modifying the molecular structure of epoxy itself to increase the toughness of its cured product, the most effective way to toughen epoxy resin is to add various toughening additives, such as adding core-shell particles, rubber particles, liquid rubber, thermoplastic resins and other additives to effectively improve the toughness of epoxy, but these toughening additives will also significantly reduce the heat resistance of epoxy. Therefore, the epoxy industry has been looking for excellent toughening additives that can effectively improve the toughness of epoxy without reducing properties such as strength and heat resistance. Similarly, other thermosetting resins such as vinyl resin, unsaturated resin, phenolic resin, urea-formaldehyde resin, etc., also have similar requirements and need to overcome the shortcomings of thermosetting resins, that is, high strength but poor toughness. Summary of the invention

[0005] The purpose of the present invention is to provide an unsaturated modified polyurethane resin obtained by recycling and processing polyurethane solid materials. The unsaturated modified polyurethane resin can be used to manufacture modified thermosetting resin products prepared from the modified polyurethane resin and to improve the toughness of the modified thermosetting resin products prepared from the modified polyurethane resin. The unsaturated modified polyurethane resin plays the role of an effective toughening agent and can effectively improve the toughness of various thermosetting resins, such as epoxy resins, vinyl resins, unsaturated resins, etc., thereby achieving the purpose of improving the recycling rate of polyurethane solid waste and improving the performance of thermosetting resins as a high-efficiency toughening agent.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A method for preparing a modified polyurethane resin used as a toughening aid, wherein the modified polyurethane is obtained by treating an initial polyurethane, wherein the treatment comprises the following steps:

[0008] Step A: subjecting the initial polyurethane to a degradation reaction with a degradation agent having an active group, breaking at least a portion of the molecular chain of the initial polyurethane, and obtaining a resin intermediate containing a molecular fragment of the initial polyurethane and the active group;

[0009] Wherein, the initial polyurethane comprises a thermoplastic polyurethane having a linear or branched molecular structure and a thermosetting polyurethane having a cross-linked network molecular structure, and the molecular weight of the initial polyurethane is not less than 10000 g / mol;

[0010] Step C: reacting the resin intermediate with a grafting agent having a grafting group to prepare a modified polyurethane resin containing an initial polymer molecular chain fragment having a chain extension group;

[0011] The grafting reaction includes one or more combinations of esterification, acylation, amide condensation or transesterification;

[0012] The grafted group is one or more selected from amide group, urea group, hydroxyl group, carboxyl group, ester group, acid anhydride group or epoxy group.

[0013] In the preparation process of the active hydrogen-containing resin intermediate, it is obtained by a degradation reaction between an initial polyurethane and a degradation agent having an active group.

[0014] Furthermore, in step A, the degradation reaction is an alcoholysis reaction.

[0015] The degradation agent comprises a polyol, wherein the polyol comprises a diol and / or a high-functionality polyol,

[0016] The diols include low molecular weight C2-C6 diols,

[0017] The low molecular weight C2-C6 diol includes one or more combinations of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, dipropylene glycol, ethylene glycol ketone, propylene glycol ketone or neopentyl glycol.

[0018] The high-functionality polyol includes glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, sucrose polyol, sorbitol or polyether polyol.

[0019] The temperature of the alcoholysis reaction is 110-150°C, 150-170°C, 170-180°C, 180-200°C, 200-220°C or 220-250°C.

[0020] The alcoholysis reaction time is 0.5 to 2 hours, 2 to 3 hours, 3 to 6 hours, 6 to 12 hours, 12 to 24 hours, 24 to 48 hours or 48 to 64 hours.

[0021] Alcoholysis reaction in the present invention is to add alcohol degradation agent (middle and long chain polyol, small molecule polyol etc.) to polyurethane solid material, and then degrade the macromolecular chain in it by heating mode to make it depolymerize into liquid polyols containing polyhydroxyl and amino. These liquid polyols are specially referred to as resin intermediates containing active hydrogen in this patent, which can be reused in step B by esterification to prepare unsaturated modified polyurethane resin, and can also be further separated, purified and classified before being reused, such as deamination, removal of particles etc., and can also carry out grafting reaction before esterification. Actual alcoholysis process can add a certain amount of co-alcoholization agent and / or catalyst etc. according to specific needs, such as one or more combinations in amines, phosphate esters, alcoholamines, alkali metal and alkaline earth metal carboxylates and hydroxides or other metal salts (tin, titanium etc.).

[0022] Furthermore, in the step C, the grafting reaction is an acylation reaction and / or an esterification reaction.

[0023] Furthermore, the modified polyurethane resin contains active terminal double bonds.

[0024] Furthermore, in the step C, the acylation reaction and / or esterification reaction is a ring-opening reaction between the active hydrogen of the resin intermediate and the grafting agent containing the anhydride group.

[0025] Furthermore, the grafting agent includes a cyclic acid anhydride, and the cyclic acid anhydride includes one or more combinations of monofunctional acid anhydride, difunctional acid anhydride or free acid anhydride.

[0026] Furthermore, the cyclic anhydride includes one or more combinations of succinic anhydride, maleic anhydride, phthalic anhydride, nadic anhydride, methylhexahydrophthalic anhydride, chlorendic anhydride, pyromellitic anhydride or trimellitic anhydride.

[0027] Further, the grafting agent includes a cyclic anhydride, and the cyclic anhydride includes one or more combinations of succinic anhydride, maleic anhydride, phthalic anhydride, nadic anhydride, methylhexahydrophthalic anhydride, chlorendic anhydride, pyromellitic anhydride or trimellitic anhydride. The grafting reaction includes a ring-opening reaction of the active hydrogen-containing resin intermediate and the cyclic anhydride, that is, the active hydrogen-containing resin intermediate obtained by the alcoholysis reaction is further converted into a modified polyurethane resin containing an initial polyurethane molecule fragment with a chain extension group through a grafting reaction.

[0028] Furthermore, the esterification reaction is an esterification reaction with acrylic acid and / or methacrylic acid.

[0029] Further, the grafting agent includes one or more selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, mono-2-(acryloyloxy)ethyl phthalate, mono-2-(methacryloyloxy)ethyl phthalate, N-(carboxyphenyl)maleimide, N-(carboxyphenyl)methacrylamide, N-(carboxyphenyl)acrylamide or methacryloyl chloride.

[0030] The resin intermediate containing active hydrogen can be directly esterified, or the resin intermediate containing active hydrogen can be directly grafted with anhydride groups, or the resin intermediate containing active hydrogen can be first grafted with anhydride groups and then esterified, both of which can obtain unsaturated modified polyurethane resins containing active terminal double bonds.

[0031] Furthermore, the active terminal double bond in step C is preferably an active double bond based on acrylate and / or methacrylate.

[0032] The present invention claims a modified polyurethane resin prepared by the above-mentioned modified polyurethane resin preparation method.

[0033] Furthermore, the modified polyurethane resin is used to manufacture modified thermosetting resin products prepared from the modified polyurethane resin and to improve the toughness of the modified thermosetting resin products prepared from the modified polyurethane resin. It can be used as a toughening aid, and can also be called a toughness improving modifier or a high-toughness crosslinking agent.

[0034] Furthermore, the modified thermosetting resin product prepared by the modified polyurethane resin is prepared by blending the modified polyurethane resin with a thermosetting resin, and the thermosetting resin is an unsaturated resin, an epoxy resin or a vinyl resin.

[0035] The present invention also claims to protect the use of any of the above modified polyurethane resins in improving the toughness of modified thermosetting resin products prepared from the modified polyurethane resin.

[0036] The present invention further provides a method for preparing a modified epoxy resin by using the modified polyurethane resin obtained by any of the above methods for preparing a modified polyurethane resin as a resin toughening modifier, comprising the following steps:

[0037] Step A1: uniformly mixing the epoxy resin, the curing agent and the modified polyurethane resin to obtain an epoxy mixture;

[0038] Step A2: heating and curing the epoxy mixture.

[0039] Step A3: Cooling the epoxy mixture after heating and curing to obtain the modified epoxy resin.

[0040] Furthermore, the curing agent is a compound that can react with the chain extending group, or a compound that can induce the chain extending group to react with each other.

[0041] The reactive functional groups of the compound to react include one or a combination of free radical initiators, isocyanate groups, acid anhydrides, carboxyl groups, epoxy groups, amine groups, amide groups or aldehydes;

[0042] The curing agent also includes an accelerator compatible with the free radical initiator;

[0043] The accelerator includes metal salts, organic amines, including cobalt salts, copper salts, zinc salts or aniline accelerators.

[0044] Furthermore, the curing agent contains anhydride or amine reactive functional groups.

[0045] Furthermore, in step A1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the epoxy mixture;

[0046] In the step A2, the temperature of the heating and curing is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C.

[0047] In the step A3, the epoxy mixture after heating and curing is cooled to below 50°C.

[0048] The present invention claims protection for the modified epoxy resin prepared by the above-mentioned method for preparing a modified epoxy resin, wherein the impact strength of the modified epoxy resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to the epoxy resin; the tensile elongation at break of the modified epoxy resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to the epoxy resin, thereby improving the toughness of the raw thermosetting resin.

[0049] The present invention further provides a method for preparing a modified vinyl resin by using the modified polyurethane resin obtained by any of the above methods for preparing a modified polyurethane resin as a resin toughening modifier, comprising the following steps:

[0050] Step B1: uniformly mixing a vinyl resin, a free radical initiator, the modified polyurethane resin and an accelerator to obtain a resin mixture;

[0051] Step B2: heating and curing the resin mixture.

[0052] Step B3: Cooling the resin mixture after heating and curing to obtain the modified vinyl resin.

[0053] Furthermore, in step B1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the resin mixture;

[0054] In the step B2, the heating and curing temperature is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C.

[0055] In the step B3, the resin mixture after heating and curing is cooled to below 50°C.

[0056] The curing process of vinyl resins is achieved by free radical curing under conditions of adding free radical initiators and / or heating;

[0057] The free radical initiator includes a heat-sensitive free radical initiator and a photosensitive free radical initiator. The heat-sensitive free radical initiator includes a peroxide, a persulfide, a peroxycarbonate, a peroxyboric acid, an azo compound or other suitable free radical initiator that can initiate the curing of a double bond-containing compound.

[0058] More preferably, the free radical initiator includes tert-butyl peroxyisopropyl carbonate, methyl ethyl ketone peroxide, potassium persulfate, cumene hydroperoxide, dibenzoyl peroxide, tert-butyl perbenzoate or 2,4-di-tert-butyl peroxide isopropylbenzene.

[0059] The present invention claims protection for the modified vinyl resin obtained by the above-mentioned method for preparing modified vinyl resin, wherein the impact strength of the modified vinyl resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to the vinyl resin; the tensile elongation at break of the modified vinyl resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to the vinyl resin, thereby improving the toughness of the raw thermosetting resin.

[0060] The present invention further provides a method for preparing a modified unsaturated resin by using the modified polyurethane resin obtained by any one of the above methods for preparing a modified polyurethane resin as a resin toughening modifier, comprising the following steps:

[0061] Step C1: uniformly mixing an unsaturated resin, a free radical initiator, the modified polyurethane resin and an accelerator to obtain an unsaturated resin mixture;

[0062] Step C2: heating and curing the unsaturated resin mixture,

[0063] Step C3: Cooling the unsaturated resin mixture after heating and curing to obtain the modified unsaturated resin.

[0064] Furthermore, in the step C1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the unsaturated resin mixture;

[0065] In the step C2, the temperature of the heating and curing is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C.

[0066] In the step C3, the unsaturated resin mixture after heating and curing is cooled to below 50°C.

[0067] The present invention claims protection for the modified unsaturated resin obtained by the method for preparing a modified unsaturated resin, wherein the impact strength of the modified unsaturated resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to the unsaturated resin; the tensile elongation at break of the modified unsaturated resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to the unsaturated resin, thereby improving the toughness of the raw thermosetting resin.

[0068] The curing process of unsaturated resins is achieved by free radical curing under conditions of adding free radical initiators and / or heating;

[0069] Furthermore, the resin toughening modifier obtained by any of the above-mentioned methods for preparing unsaturated modified polyurethane resins is used to prepare toughened epoxy resins.

[0070] Epoxy can choose anhydride or amine curing agent, and the curing reaction temperature is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C. Preferably, the curing reaction temperature is 100-160°C; more preferably, the curing reaction temperature is 100-140°C.

[0071] Further, the curing reaction time is 0.5 to 2 hours, 2 to 3 hours, 3 to 6 hours, 6 to 12 hours, 12 to 24 hours or 24 to 48 hours. Preferably, the curing reaction time is 2 to 12 hours, and more preferably, the curing reaction time is 3 to 6 hours.

[0072] The present invention surprisingly found that the degraded polyurethane material obtained by alcoholysis, i.e., the resin intermediate, can be directly subjected to an esterification reaction to obtain an unsaturated modified polyurethane resin containing active terminal double bonds without additional separation and purification. The unsaturated modified polyurethane resin can be directly used as a resin toughening modifier to improve the toughness of epoxy resin, and while improving its toughness, other properties of the thermosetting resin will not be damaged.

[0073] Furthermore, in step C, the weight percentage of the resin toughening modifier to the total weight of the toughened thermosetting resin is 1-40%, preferably 2-30%, more preferably 3-25%, and most preferably 3-20%;

[0074] The present invention further provides a toughened thermosetting resin obtained by any one of the above methods for preparing a toughened thermosetting resin.

[0075] In a first aspect, the present invention provides a method for producing a modified polymer, wherein the modified polymer is obtained by treating an initial polymer, wherein the treatment comprises the following steps:

[0076] Step A: the initial polymer reacts with a degradation agent containing an active group to break at least a portion of the molecular chain of the initial polymer to form a resin intermediate containing molecular chain fragments of the initial polymer with an active group;

[0077] Step C: reacting the resin intermediate with a grafting agent having a grafting group to prepare a modified resin containing an initial polymer molecular chain fragment having a chain extension group, wherein the chain extension group can be on the degradation agent molecule or on the grafting agent molecule;

[0078] Step I: then the modified resin is mixed with a curing agent, and the initial polymer molecular chain fragments in the modified resin are reconnected into new macromolecules through the reaction of the curing agent with the chain extension group or through the curing agent initiating the reaction of the chain extension groups to each other, thereby preparing a modified polymer.

[0079] In a second aspect, the present invention also provides another method for producing a modified polymer, wherein the modified polymer is obtained by treating an initial polymer, wherein the treatment comprises the following steps:

[0080] Step C: firstly reacting the initial polymer with a grafting agent containing a chain extending group to break the polymer molecular chain to form a modified resin containing the initial polymer molecular chain fragments with the chain extending group;

[0081] Step I: mixing the modified resin with the curing agent, and reconnecting the initial polymer molecular chain fragments in the modified resin into new macromolecules through the reaction of the curing agent with the chain extension group or through the curing agent initiating the reaction of the chain extension groups, thereby preparing the modified polymer.

[0082] In a third aspect, the present invention also provides another method for producing a modified polymer, wherein the modified polymer is obtained by treating an initial polymer, wherein the treatment comprises the following steps:

[0083] Step I: then mixing the modified resin obtained by the method for producing a modified polymer according to the first aspect or the second aspect with a curing agent, and then cooling the mixed resin to obtain a semi-cured material containing the curing agent.

[0084] Step G: The semi-cured material is heated to make the curing agent react with the chain extension group or the curing agent triggers the chain extension group to react with each other so that the initial polymer molecular chain fragments in the modified resin are reconnected into new macromolecules to prepare a modified polymer.

[0085] Furthermore, the heating method includes one or more combinations of conduction, infrared, microwave, radiation, ultraviolet, ultrasonic, heat medium, hot air or electromagnetic wave heating methods.

[0086] Optionally, in the method for manufacturing modified polymers in the first to third aspects above, step 1 also includes the step of adding fillers or other additives to the modified resin and / or the step of impregnating the modified resin into fibers, thereby obtaining a composite semi-cured material, and then obtaining a composite material with the modified polymer as the matrix; the filler includes a solid or liquid additive that does not chemically react with the initial polymer.

[0087] Optionally, the initial polymer contains fillers or fibers, and in steps a to f, at least a portion of the fillers or fibers in the initial polymer are retained to obtain a composite semi-cured material. Further, in step g, a modified polymer containing fillers and / or reinforcing materials that meets the requirements of the target application is obtained, that is, a composite material with the modified polymer as a matrix.

[0088] Through this method, the purification step of the initial polymer can be eliminated, reducing costs and avoiding pollution from purification by-products, while the structure and performance of the original filler and / or reinforcement material can be fully retained and utilized to obtain a modified polymer containing fillers and / or reinforcement materials that meets the requirements of the target application, that is, a composite material with the modified polymer as the matrix.

[0089] In the industrial-scale implementation of this method, the initial polymer mixed waste of unknown composition is firstly modified using a standard initial degradation agent and / or grafting agent to obtain an initial modified resin, and then the initial modified resin is solidified to become an initial modified polymer, and then the initial modified polymer is compared with the performance of the target polymer, the initial modified resin is characterized by molecular structure and compared with the native precursor resin of the target polymer, and then the different degradation agents, grafting agents, curing agents, active diluents, other types of resins, and other additives in steps A to F are adjusted, including but not limited to the variety, proportion and content of the aforementioned factors. One or more factors are adjusted, and finally the performance of the modified polymer resin is not lower than that of the target polymer resin, thereby achieving the performance requirements of the modified polymer for the target application.

[0090] Preferably, in step A or C, the molecular structure of the modified resin can be adjusted by combining different types of initial polymers, thereby adjusting the performance of the modified polymer.

[0091] More preferably, a compounding step can be added between step A and step C, and the molecular structure of the modified resin can be adjusted by compounding different resin intermediates prepared using different types of initial polymers to obtain a mixed modified resin intermediate, thereby adjusting the performance of the modified polymer.

[0092] Another preferred method is to add a compounding step between step C and step E. A mixed modified resin can be obtained by compounding different modified resins made from different types of initial polymers, thereby adjusting the molecular structure of the modified resin and further adjusting the properties of the modified polymer.

[0093] These three priority methods can all use different types of polymer waste as initial polymers and changes in their proportions to adjust the molecular structure of the modified resin, thereby improving the performance of the modified polymer. Compared with adjusting the molecular structure of the modified resin by adding other fresh chemical raw materials, this method reduces costs and increases the consumption of polymer waste.

[0094] Another preferred method is to add a mixture to obtain a modified resin mixture after step C, and adjust the molecular structure and composition of the modified resin by adjusting the type and content of the mixture, thereby adjusting the performance of the modified polymer. Preferably, the mixture includes a combination of one or more of a diluent, other types of resins, fillers, and fibers.

[0095] Furthermore, the initial polymer may be an unfilled polymer or a polymer containing fillers, additives or reinforcing materials, and may be a thermoplastic polymer or a thermosetting polymer. Thermoplastic polymers include but are not limited to polyethylene, polypropylene, polyolefins, polyvinyl chloride, polyesters, polyamides or thermoplastic polyurethanes; thermosetting polymers include but are not limited to rubber, polyurethane, unsaturated polyester resins, epoxy resins, vinyl resins, acrylic resins or silicone resins.

[0096] Furthermore, the initial polymer includes a thermoplastic polymer with a linear or branched molecular structure, a thermosetting polymer with a cross-linked network molecular structure, a pure polymer or a polymer composite containing fillers and / or fibers, and the molecular weight of the initial polymer is not less than 10,000 g / mol.

[0097] In another aspect, the present invention claims a modified polymer prepared by any one of the above methods.

[0098] The principles of resin modification methods based on other polymers and their products and applications are the same as this and also fall within the protection scope of the present invention.

[0099] The present invention also claims a method for preparing a modified polymer as a resin intermediate, wherein the modified polymer is obtained by treating an initial polymer, the treatment comprising the following steps:

[0100] A: The initial polymer is subjected to a degradation reaction with a degradation agent having an active group, thereby breaking at least a portion of the molecular chain of the initial polymer and obtaining a resin intermediate containing molecular chain fragments of the initial polymer having an active group.

[0101] The initial polymer includes a thermoplastic polymer with a linear or branched molecular structure and a thermosetting polymer with a cross-linked network molecular structure, and the molecular weight of the initial polymer is not less than 10000 g / mol.

[0102] Further, the thermoplastic polymer includes polyethylene, polypropylene, polyolefin, polyvinyl chloride, polyester, polyamide or thermoplastic polyurethane, and the thermosetting polymer includes rubber, polyurethane, unsaturated polyester resin, epoxy resin, vinyl resin, acrylic resin or silicone resin. Preferably, the initial polymer molecular chain carries a chain-breaking group, and in step A, the molecular main chain of the initial polymer is disconnected from the chain-breaking group, and the chain-breaking group includes -N(H)n-, -NH-(CO)-O-, -C=C-, -C≡C-, -C≡CN-, -(CO)-, -(CO)-O-, -O-, -HN-(CO)-NH-, -(CO)-NH-, -NH-(CS)-O-, -C=C-, -S-, -HN-CS-NH-, -CS-NH-, heterocyclic, cyclic, aromatic, hexyl, macrocyclic, polyhedral, isomer or polypeptide, one or more combinations thereof. Preferably, the initial polymer molecule chain has a side group, the side group does not include a hydrogen atom, and the side group reacts synergistically with the degradation agent to help the initial polymer molecule break. The degradation reaction of the aforementioned step A includes one or more combinations of pyrolysis, hydrolysis, alcoholysis, aminolysis, acidolysis, alkaline hydrolysis, alcohol-alkali reaction, hydrogenolysis or acidolysis.

[0103] Preferably, the degradation reaction comprises the following reactions:

[0104] R1-A-(R2S)+R3-B-→R1-(A1)-R3-B1-+(R2S)-B2-

[0105] Wherein, -R1-A-(R2S)- is the initial polymer, A is the chain-breaking group, S is the side group, R3-B- is the degradation agent, and -B- is the active group of the degradation agent; R1-(A1)-R3-B1- and (R2S)-B2- are initial polymer molecular fragments formed after the initial polymer chain breaks, -A1- is the group formed after the degradation reaction of the chain-breaking group A, -B1- and -B2- are respectively active groups formed by the active end group B of the degradation agent at the two ends of the broken molecular chain, and the active groups A1 or B1 or B2 participate in subsequent reactions.

[0106] Preferably, the weight ratio of the initial polymer to the degradation agent is 1:0.1-0.4, 1:0.4-2, 1:2-5 or 1:5-15.

[0107] As a typical application of the present invention, polyurethane (PU) is a typical representative of the initial polymer, and ranks fifth in the total polymer output in terms of production scale, and has a large application market, so the present invention can use polyurethane as the initial polymer for recycling and modification. The present invention provides a method for modifying polyurethane, which uses the solidified initial polymer, especially polyurethane waste, to manufacture the modified polymer, reduces the use of isocyanate in the polyurethane resin manufacturing process, avoids moisture sensitivity of the resin, has a longer process operation time, optimizes the polyurethane molecular structure, and significantly improves the comprehensive performance of the modified polymer.

[0108] Existing polyurethane is a material obtained by reacting an isocyanate reactant containing an isocyanate group and an isocyanate reactant containing an active hydrogen atom that can react with the isocyanate group. Commonly used isocyanate reactants are polyols containing hydroxyl groups, polyamines containing amino groups, thiol compounds containing mercapto groups, and combinations thereof. According to performance characteristics, it is mainly divided into three categories: rigid polyurethane, soft polyurethane and polyurethane elastomer. According to product and application classification, polyurethane rigid foam insulation materials, polyurethane soft foam cushioning materials and polyurethane elastomer wear-resistant materials account for the vast majority. Of course, polyurethane is also widely used in coatings, adhesives, fibers, thermoplastic materials and other special polymers. Polyurethane resin is usually prepared and used as a two-component resin system. The component containing isocyanate groups is usually called an isocyanate component, also called a black material component; the component containing isocyanate group reactive functional groups is usually called a polyol component, also called a white material component. The existing polyurethane production method includes using a two-component resin directly prepared from a polyol component and an isocyanate component to manufacture polyurethane. Since the isocyanate group is very easy to react with water to generate carbon dioxide and urea, the generated polymer generates bubbles, the performance is reduced, and the gel time is too fast, which requires rapid operation during the production process. The process operation time is limited, and the process is often carried out in a sealed, high-temperature, and high-pressure environment, which places high requirements on production equipment. Especially in the composite material industry, such as traditional pultrusion, winding, hand lay-up, injection, and vacuum infusion processes, the resin is required to be insensitive to moisture, have a process operation time of more than 4 hours, and cure at room temperature or below 80°C. This is not met by existing polyurethane resins. Therefore, existing polyurethane resins can only develop special processes, use complex equipment and molds to shorten the operation time, and isolate moisture to manufacture polyurethane composite materials, which also seriously restricts the application scope of polyurethane.

[0109] Based on the problems existing in the existing polyurethane manufacturing methods, the solution of the present invention is that in step A, the initial polymer is a thermoplastic polyurethane TPU having a linear or branched molecular structure and / or a thermosetting polyurethane having a cross-linked network molecular structure; wherein the initial polymer molecular chain carries a chain-breaking group, and in step A, the initial polymer is reacted with a degradation agent to disconnect the molecular weight of the initial polymer from the chain-breaking group.

[0110] Furthermore, in step A, the initial polyurethane is mixed with the degradation agent to undergo a degradation reaction, thereby obtaining a resin intermediate containing molecular fragments and active groups of the initial polyurethane. Preferably, the initial polyurethane is subjected to a pulverization treatment, and the pulverization treatment includes but is not limited to a combination of one or more of the methods of crushing, shearing, grinding, ball milling, grinding, air flow pulverization, ultrasonic pulverization, etc.; the mixing method of the initial polyurethane and the degradation agent includes but is not limited to a combination of one or more of the methods of high-speed stirring, centrifugal stirring, kneading, mixing, screw extrusion, grinding, and ball milling;

[0111] Further, the chain-breaking groups include -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, The degradation reaction includes one or more of alcoholysis, alkaline hydrolysis, hydrolysis, aminolysis, pyrolysis, alcohol-glaze reaction, hydrogenolysis or acidolysis; the degradation reaction may include the following reactions respectively:

[0112] Alcoholysis: PU+HO—R—OH to obtain a polyol mixture

[0113] Hydrolysis method: PU + water to obtain polyol + polyamine

[0114] Alkaline hydrolysis: PU + NaOH to obtain amine + alcohol + Na2CO3

[0115] Ammonolysis: PU + NH3 to obtain polyol + amine + urea

[0116] Pyrolysis: PU + high temperature to obtain a mixture of gaseous and liquid fractions

[0117] Hydrocracking method: PU+H2 high temperature and high pressure to obtain a mixture of oil and gas

[0118] Further, in step A, the initial polyurethane as the initial polymer is a polymer compound containing a chain-breaking group (AB), a main chain X, and a Y, and is prepared from an initial isocyanate XA a and initial polyol YB b The reaction generates; the degradation agent is MC cThe active group C of the degradation agent reacts with the chain-breaking group (AB) to break the initial polyurethane molecules, forming a resin intermediate containing initial polymer molecular fragments with new active groups B and C. The degradation reaction is as follows:

[0119]

[0120] Wherein, A is the isocyanate group in the initial polyurethane, B is the hydroxyl group in the initial polyurethane, (AB) is the carbamate group in the initial polyurethane; X is the initial isocyanate backbone; Y is the initial polyol backbone; M is the degradation agent backbone; C is the active group of the degradation agent, including hydroxyl, active hydrogen, amine or alkali metal group; a, b, c are functionalities respectively. The above is a typical degradation reaction mechanism, where a=2, b=3, c=1, and the degradation reactions of other a, b, c functional group combinations are similar and fall within the protection scope of the present invention.

[0121] Further, in step A, the degradation agent contains at least one active end group, and the active end group includes one or more of a hydroxyl group, an amide group, an acyl salt group, a urea group, an amine group, a carboxyl group, an anhydride group, a carboxylate group, an unsaturated double bond or triple bond, an ester group, a cyano group, a nitro group, a carbonyl group or an epoxy group.

[0122] Preferably, the initial polyurethane includes carbamate groups, the degradation agent includes hydroxyl groups, and in the degradation reaction the hydroxyl groups react with the carbamate groups and open at least a portion of the carbamate bonds to generate a resin intermediate containing initial polyurethane molecular fragments with active amino and hydroxyl groups.

[0123] As a typical example of the present invention, the initial polymer is polyurethane, the main chain of which contains carbamate groups, and the degradation reaction includes alcoholysis reaction; the active end group contained in the degradation agent is hydroxyl group, and in the degradation reaction, the hydroxyl group reacts with the chain-breaking group and opens at least a part of the urethane bond on the initial polymer molecular chain to generate a resin intermediate containing the initial polyurethane molecular fragment and the linear or branched molecular structure of the active group hydroxyl group. The degradation reaction includes the following reactions:

[0124] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0125] Among them, -NHCOO- is a carbamate group; R3(OH)n is a degradation agent, and n is greater than 1; -R1NHCOOR3(OH)(n-1)- is a molecular chain fragment containing R1 and a carbamate group and an active group hydroxyl group in the initial polyurethane molecular chain, and -R2OH is a molecular chain fragment containing R2 and at least one active group hydroxyl group in the initial polyurethane molecular chain.

[0126] Furthermore, since the chemical structure of polyurethane contains urea chain -NHCONHR- in addition to carbamate chain -NHCOOR-, the following side reactions also occur during the degradation reaction:

[0127] Side reactions of urea groups:

[0128] -R1-NH-CO-NH-R1-+HO-R3-OH→-R1NHCOOR3OH+-R1NH2

[0129] There are also side reactions such as thermal degradation of carbamate and urea groups:

[0130] -R1-NH-CO-O-R2-→-RNCO+HOR2

[0131] -R1-NH-CO-O-(CH2)2-R2-→-R1NH2+CO2+CH2=CHR2

[0132] -R1-NH-CO-OO-R2-→-R1NHR2-+CO2

[0133] -R1-NH-CO-NH-R4-→--R1-NCO+R4NH2

[0134] The above side reactions will eventually generate compounds with hydroxyl or amine groups.

[0135] The above-mentioned side reactions will eventually generate compounds with hydroxyl or amine groups, which can make the grafting agent react with the amine-containing compound, so that there is no need to take the steps of separating and purifying the amine compound and the polyol for the resin intermediate.

[0136] Furthermore, the amine substances in the resin intermediates are further functionalized through the Michael addition reaction, which can cause a 1,4-conjugate addition reaction between the amino group and the active double bond of the amine substance. These active double bonds come from substances such as α,β-unsaturated aldehydes, ketones, esters, nitriles, and nitro compounds. The amino group undergoes a Michael addition reaction through its active hydrogen and active double bond, and the reaction is as follows:

[0137]

[0138] Y=CHO,C=O,COOR,NO2,CN

[0139] X=H, alkyl, aryl

[0140] R 1 =Alkyl, aryl

[0141] R 2 , R 3, R4=H, alkyl, aryl

[0142] Preferably, the molar ratio of active double bonds to active hydrogen of amino groups is 0-100, preferably 0.01-50, preferably 0.05-20, preferably 0.1-5, preferably 0.2-3, preferably 0.3-2, preferably 0.4-1.5, preferably 0.5-1.1, preferably 0.7-1.

[0143] Furthermore, among the grafting agents, representative compounds based on such α,β-unsaturated aldehydes, ketones, esters, nitriles, and nitro compounds include, but are not limited to, hydroxypropyl methacrylate, acrylonitrile, ethyl acrylate, nitroethylene, acrolein, or propylene ethyl ketone.

[0144] Further, the degradation agent includes a polyol, and the polyol includes a diol and / or a high-functionality polyol. The diol includes a low molecular weight C2-C6 diol, preferably ethylene glycol, propylene glycol, 1,4-butanediol monoethylene glycol, monopropylene glycol or neopentyl glycol. The high-functionality polyol includes glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, sucrose polyol or sorbitol, and also includes various polyether polyols based on small molecule initiators, such as NJ-301, NJ-303, NJ-3063, NJ-430H, NJ-6305C, NJ-403, NJ-4110, NJ-330N, NJ-204, etc.

[0145] Furthermore, the polyol is used as an alcoholysis agent in combination with an alcoholysis co-agent, and the alcoholysis co-agent is a tertiary amine.

[0146] Furthermore, the alcoholysis agent is used in combination with a metal organic compound as a catalyst to effectively promote the alcoholysis reaction and reduce the content of polyamines in the product; preferably, the metal organic compound used as a catalyst includes Ti[O(CH2)3CH3]4 or CH3COOK, and most preferably, Ti[O(CH2)3CH3]4 is selected, and the hydroxyl value and viscosity of the obtained product are more moderate.

[0147] Furthermore, a catalyst is added to the alcoholysis agent to accelerate the degradation reaction, the catalyst is selected from one or more of guanidines, amidines, tins or amines, and the catalyst includes one or more of triethylamine, 1,5,7-triazidobicyclo(4.4.0)dec-5-ene, 1,8-diazabicycloundec-7-ene, benzenesulfonic acid, (4-methylphenyl)diphenylsulfoniumtrifluoromethanesulfonic acid, tin salts, zinc salts, calcium salts, magnesium salts or cobalt salts; preferably, the amount of the catalyst added is 0.01wt%-10wt% of the initial polyurethane.

[0148] Preferably, the alcoholysis agent comprises one or a combination of diols and high-functionality polyols, and the weight ratio of diols to high-functionality polyester polyols is 1:0-0.3, 1:0.3-0.6, 1:0.6-1, 1:1-2 or 1:2-4. If the ratio of diols is too high, more diols will remain in the product, making the post-treatment of the product difficult. At the same time, the alcoholysis product containing free diols is difficult to completely remove, resulting in problems such as too high hydroxyl value or difficulty in adjustment.

[0149] Preferably, the initial polymer is polyurethane waste, including refrigerator insulation rigid foam, cold storage insulation rigid foam, refrigerated truck and refrigerated container insulation rigid foam, building insulation rigid foam and other insulation rigid foam, sofa, seat, mattress soft foam, packaging cushion sponge, shoe sole, roller rubber, screen, conveyor belt, other elastomer, spandex or TPU products. The method for manufacturing modified polyurethane by the method of obtaining a resin intermediate through degradation reaction, the obtained resin intermediate can be used to manufacture modified thermosetting resin products prepared by modified polyurethane resin, coatings, adhesives, structural adhesives and other chemicals, including PU rigid foam, soft foam, elastomer, composite material, epoxy resin crosslinking agent, unsaturated resin, vinyl resin modifier and polyurethane rubber crosslinking agent.

[0150] Preferably, the weight ratio of polyurethane waste PU as the initial polymer to the degradation agent is 1:0.1-0.3, 1:0.3-0.5, 1:0.5-1, 1:1-2, 1:2-4, 1:4-8 or 1:8-15. If the ratio of PU is too large, only a partial reaction will occur, and the density and viscosity of the product will also increase accordingly. If it is too small, the cost of removing the unreacted degradation agent will be too high.

[0151] Preferably, the temperature of the alcoholysis reaction is 110-150°C, 150-170°C, 170-180°C, 180-200°C, 200-220°C or 220-250°C. Too low a reaction temperature prolongs the reaction time. Although too high a reaction temperature is beneficial to increasing the alcoholysis reaction rate and shortening the reaction time, it increases the content of free amines in the final product; and makes the amine value or hydroxyl value of the final product too high.

[0152] The alcoholysis reaction time is 0.5 h to 64 h, preferably 0.5 to 2 h, 2 to 3 h, 3 to 6 h, 6 to 12 h, 12 to 24 h, 24 to 48 h or 48 to 64 h.

[0153] Preferably, the yield of the alcoholysis reaction is 50-60%, 60-70%, 70-80%, 80-95% or 95-100%.

[0154] Furthermore, in step A, the degradation reaction includes an alcohol reaction or an alkaline hydrolysis reaction. It includes the following reactions:

[0155]

[0156] Preferably, the base in the alkaline hydrolysis reaction can be an alkali metal hydroxide and an alkaline earth metal hydroxide, and in addition to NaO, it can also be a mixture of one or more of LiOH, KOH, and Ca(OH)2.

[0157] Further, in step A, the degradation reaction includes a hydrolysis reaction or a steam cracking method, and the degradation reaction includes the following reaction under high pressure steam and high temperature conditions:

[0158] R1-NH-CO-O-R2+H2O→-R1NH2+R2OH+CO2

[0159] The steam cracking temperature during the degradation reaction is 200-410°C, preferably 220-380°C.

[0160] Furthermore, the hydroxyl value of the resin intermediate obtained in step A is 10-50 mg KOH / g, 50-100 mg KOH / g, 100-180 mg KOH / g, 180-300 mg KOH / g, 300-500 mg KOH / g, 500-700 mg KOH / g or 700-1000 mg KOH / g.

[0161] Furthermore, the viscosity (25°C) of the resin intermediate obtained in step A is 50-200mPa·s, 200-500mPa·s, 500-1000mPa·s, 1000-2000mPa·s, 2000-10000mPa·s, 10000-20000mPa·s, 20000-60000mPa·s, 60000-200000mPa·s, 200000-600000mPa·s or 600000-1800000mPa·s.

[0162] Furthermore, the total amine value (KOH dosage) of the resin intermediate prepared in step A is 0-40 mg / g, 40-80 mg / g, 80-200 mg / g or 200-1000 mg / g.

[0163] Furthermore, in step A, the degradation reaction includes a pyrolysis reaction of the polyurethane waste, and the pyrolysis reaction includes cracking the initial polymer polyurethane waste at 180-400° C., and the products are isocyanate and recovered polyol, and the isocyanate and the recovered polyol are fractionated and collected.

[0164] Furthermore, step A also includes a step of removing at least a portion of the degradation products, and the removal step includes a combination of one or more of reduced pressure distillation, separation, filtration, extraction, and fractionation. Preferably, a reduced pressure distillation step is included to remove at least a portion of the unreacted degradation agent, and the degradation agent can be collected, recovered, and reused after removal. More preferably, the reduced pressure temperature is 65-95°C, 95-120°C, 120-150°C, or 150-200°C; the reduced pressure distillation pressure is 0.01-2 mmHg, 2-5 mmHg, 5-20 mmHg, 20-100 mmHg, or 100-400 mmHg. Preferably, in step A, diol is used as a degradation agent, other high-functionality polyols are added to the degradation product to reduce the viscosity of the reaction product, and then all or part of the diol is removed by reduced pressure distillation for recycling, and the weight ratio of the diol to the high-functionality polyol is 1:0-0.3, 1:0.3-0.6, 1:0.6-1, 1:1-2, 1:2-4, 1:4-9. If the ratio of diol is too high, more diol will remain in the product, making the post-processing of the product difficult. At the same time, the alcoholysis product containing free diol is difficult to completely remove, resulting in problems such as too high hydroxyl value or difficulty in adjustment; preferably, the diol is ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, and dipropylene glycol. The resin intermediate obtained in this way has good performance and low viscosity.

[0165] On the other hand, the present invention claims a modified polymer as a resin intermediate prepared by any one of the above methods.

[0166] The present invention also provides a method for obtaining a modified polymer by subjecting a resin intermediate prepared by any of the above methods or a resin intermediate prepared by other methods to a grafting reaction treatment, wherein the modified polymer is obtained by treating an initial polymer, and the treatment comprises the following steps:

[0167] C: In step A, the degradation agent carries both active groups and chain extension groups, so that a grafting reaction is carried out simultaneously with the degradation reaction to obtain a modified polymer containing molecular fragments of the initial polymer and chain extension groups as a modified resin.

[0168] Further, the chain extension group is a functional group that can react with other groups or react with each other. Further, step C includes the following reaction:

[0169] R1-A-(R2S)+(R3C)-B-→R1-(A1C)-R3-B1-+(CR2S)-B2-

[0170] Wherein, -R1-A-(R2S)- is an initial polymer, A is a chain-breaking group, S is a side group, (R3C)-B- is a degradation agent having both an active group and a chain-extending group, -C- is a chain-extending group; -B- is an active group of the degradation agent; R1-(A1)-R3-B1- and (R2S)-B2- are initial polymer molecular fragments formed after the initial polymer chain is broken, -A1- is a group formed after the degradation reaction of the chain-breaking group A, -B1- and -B2- are respectively active groups formed by the active end group B of the degradation agent at the two ends of the broken molecular chain, and the initial polymer molecular fragments R1-(A1C)-R3-B1- and (CR2S)-B2- with the chain-extending group C can achieve molecular chain growth and / or cross-linking through the reaction of the chain-extending group C with other groups or the mutual reaction between the chain-extending groups C to obtain a modified polymer.

[0171] On the other hand, the present invention can also provide a method for obtaining a modified polymer by grafting a resin intermediate prepared by any one of the above methods, wherein the modified polymer is obtained by treating an initial polymer, and the treatment comprises the following steps:

[0172] C: After step A, the obtained resin intermediate is subjected to a grafting reaction with a grafting agent having both a grafting group and a chain extending group to obtain a modified polymer as a modified resin containing molecular fragments of the initial polymer and a chain extending group.

[0173] Furthermore, the grafting group is a functional group that can react with the active end group in the resin intermediate, and the chain extension group is a functional group that can react with other groups or react with each other.

[0174] Further, the production of the modified polymer includes the following reactions:

[0175] R1-A-(R2S)+(R3)-B-→R1-(A1)-R3-B1-+(R2S)-B2-+(R4D)-C-→R1-(A1)-R3-(B1DR4)-C-+(R2S)-(B2DR4)-C-

[0176] Wherein, -R1-A-(R2S)- is the initial polymer, A is the chain-breaking group, S is the side group, R3-B- is the degradation agent, and -B- is the active group of the degradation agent; R1-(A1)-R3-B1- and (R2S)-B2- are initial polymer molecular fragments formed after the initial polymer chain breaks, -A1- is the group formed after the degradation reaction of the chain-breaking group A, -B1- and -B2- are respectively active groups formed by the active end group B of the degradation agent at the two ends of the broken molecular chain, and the active groups A1 or B1 or B2 participate in subsequent reactions.

[0177] (R4D)-C- is a grafting agent, and D is a grafting group, which is used to react with the active groups A1, B1, and B2 in the resin intermediate so that the initial polymer molecular fragments in the resin intermediate are connected to the grafting agent molecules with the chain extender C, so that these initial polymer molecular fragments can be reconnected through the chain growth and / or cross-linking reaction of the chain extender group C to obtain a modified polymer; C is a chain extender group, and D can be a side group or on the main chain, and can be connected to a direct grafting group or a chain extender group, or can not be connected to a grafting group or a chain extender group.

[0178] According to any of the above methods for obtaining a modified polymer resin by grafting reaction, the present invention further provides the following preferred embodiments.

[0179] Furthermore, the degradation reaction includes esterification reaction, transesterification reaction, aminolysis reaction or hydrolysis reaction, and the grafting reaction includes esterification reaction, acylation reaction or transesterification reaction.

[0180] Preferably, the esterification reaction comprises direct esterification of an acid with an alcohol or phenol, comprising the following reaction:

[0181]

[0182] Among them, R' can be aliphatic or aromatic, that is, alcohol or phenol, R"COZ is an acylating agent, wherein Z can represent -OH, -X, -OR, -OCOR, -NHR, etc. R' and R" in the resulting carboxylate molecule can be the same or different.

[0183] Preferably, the esterification reaction can also be the esterification of acid derivatives with alcohols. The esterification of acid derivatives with alcohols mainly includes the reaction of alcohols with acyl chlorides, alcohols with acid anhydrides, alcohols with carboxylates, etc. The equation is as follows:

[0184]

[0185] R′OH+R″COCl→R″COOR′+HCl

[0186] R′X+R″COOM→R″COOR′+MX

[0187] Preferably, the transesterification reaction mainly includes the transesterification reaction between ester and alcohol, ester and acid, and ester and ester, and the chemical equation is as follows:

[0188]

[0189] Preferably, the esterification reaction also includes other esterification reactions, including esterification of ketene and alcohol, alcoholysis of nitrile, alcoholysis of amide, and reaction of ether and carbon monoxide to synthesize ester. For example:

[0190] ROH+CH2=CO→CH3COOR

[0191] R'OH+RCN+H2O→RCOOR′+NH3

[0192] R′OH+RCONH2→RCOOR′+NH3

[0193] CH3OCH3+CO→CH3COOCH3

[0194] Further, in step A, the initial polymer is polyurethane, including thermoplastic polyurethane TPU with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The main molecular chain of the polyurethane contains carbamate groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the carbamate groups and open at least a portion of the carbamate bonds on the initial polymer molecular chain to generate molecular chain fragments with a linear or branched molecular structure containing carbamate groups and / or hydroxyl groups.

[0195] Furthermore, the initial polymer molecular chain has chain-breaking groups, including -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, The degradation reaction includes one or more combinations of alcoholysis, alkaline hydrolysis, hydrolysis, aminolysis, thermal decomposition or acidolysis; the degradation agent includes one or more combinations of polyols, alkaline solutions, water, ammonia water, acids, acid anhydrides, carboxylates, carboxylates, polar or non-polar solvents.

[0196] Further, in step C, the grafting group includes one or more combinations of amide groups, amine groups, urea groups, hydroxyl groups, carboxyl groups, ester groups, acid anhydride groups or epoxy groups, and the chain extension group includes one or more combinations of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, carboxylates, unsaturated double bonds, ester groups, epoxy groups or aldehyde groups.

[0197] Further, the solvent is selected from one or a combination of formamide, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, trifluoroacetic acid, acetonitrile, hexamethylphosphoramide, cyclohexane, dichloromethane, pyridine, furan, chloroform, toluene, tetramethylethylenediamine or N-methylpyrrolidone;

[0198] Preferably, in the esterification reaction of step A, the acid is a straight-chain carboxylic acid, preferably, the hydroxyl group is a primary hydroxyl group, preferably, a catalyst is used to accelerate the catalytic esterification reaction or reduce the reaction temperature, and the catalyst includes a strong acid. The strong acid catalyst can reduce the activation energy of the reaction and thus accelerate the reaction. The reaction includes the following acyloxy bond cleavage mechanism:

[0199]

[0200] Strong acid catalysts include concentrated sulfuric acid, dry hydrogen chloride, p-toluenesulfonic acid, methanesulfonic acid, sulfonic acid type cation exchange resin, solid acid, dicyclohexylcarbodiimide or tetrachloroaluminum ether complex, etc. Preferably, the strong acid catalyst is p-toluenesulfonic acid, sulfonic acid type cation exchange resin, dicyclohexylcarbodiimide or tetrachloroaluminum ether complex.

[0201] Preferably, the esterification reaction includes a water removal step, including physical and chemical methods for water removal. The physical method can be azeotropic distillation, that is, adding a solvent immiscible with water to the reaction system (acid, alcohol, catalyst), such as a combination of one or more of benzene, toluene, xylene, chloroform, and carbon tetrachloride, and distilling, and removing water by fractionation. The chemical water removal method includes using anhydrous salts to absorb the water generated by the reaction, and the anhydrous salts include copper sulfate, anhydrous hydrogen chloride, acetyl chloride, thionyl chloride, chlorosulfonic acid, carbodiimide (RN=C=NR) or boron trifluoride and its ether complex.

[0202] Furthermore, the esterification reaction of step A also includes the reaction of anhydride with alcohol or phenol, and the anhydride includes acetic anhydride and maleic anhydride. Preferably, a small amount of acidic or alkaline catalyst is added to accelerate the reaction. Preferably, the catalyst includes sulfuric acid, perchloric acid, zinc chloride, ferric chloride, pyridine, anhydrous sodium ethylate, p-toluenesulfonic acid or tertiary amine. The catalytic effect of strong acid may be that hydrogen protons first react with anhydride to generate acyl cations with strong acylation ability: the catalytic effect of pyridine is generally believed to be that pyridine and anhydride form an active complex: including the following mechanisms:

[0203]

[0204] RC + O+R1OH→RCOOR1+H +

[0205]

[0206] Furthermore, the esterification reaction of step A also includes a reaction between an acyl chloride and an alcohol or a phenol, and the reaction mechanism includes:

[0207] R′OH+R″COCl→R″COOR′+HCl

[0208] Preferably, hexamethylphosphoric acid triamide is used as a solvent or magnesium chips in the esterification reaction of step A;

[0209] Alternatively, it is not necessary to prepare the acid chloride first, and only the alcohol (phenol) and the acid are mixed, and thionyl chloride and phosphorus trichloride are added to react.

[0210] Preferably, N,N'-dimethylformamide (DMF) is added to the esterification reaction in step A, so that the reaction product SO2 or the remaining strong acid is absorbed by DMF.

[0211] Preferably, N,N'-dimethylformamide (DMF) is added to the grafting reaction in step C. DMF prevents the molecular chains of the product obtained by the esterification reaction from agglomerating due to hydrogen bonds between molecules.

[0212] Further, in step A, the initial polyurethane is Y(BA) (b-a) X(AB) a Y, composed of the initial isocyanate XA a and initial polyol YB b The reaction generates; the degradation agent is MC c ; The degradation reaction includes the following reactions:

[0213]

[0214] Further, in step C, the grafting agent is D d NE e ; The grafting reaction includes the following reactions:

[0215]

[0216] Wherein, A is the isocyanate group in the initial polyurethane, B is the hydroxyl group in the initial polyurethane, (AB) is the carbamate group in the initial polyurethane; X is the initial isocyanate main chain; Y is the initial polyol main chain; M is the main chain of the degradation agent; C is the active group of the degradation agent, including hydroxyl, active hydrogen, amine, and alkali metal groups; the chain-breaking group of the initial polyurethane is (AB); N is the main chain of the grafting agent, which can participate in the molecular morphology modification of the cured polyurethane resin; D is a grafting group, which can react with (AC) and B to generate (ACD) and (BD) so that the initial polymer molecular fragments in the resin intermediate are connected to the grafting agent molecules with the chain extender E; E is a chain extender group, which can reconnect the initial polymer molecular fragments through the chain growth and / or cross-linking reaction of the chain extender group E to obtain a modified polymer; a, b, c, d, and e are functional groups, respectively. The above is a typical degradation reaction mechanism, wherein a=2, b=3, c=1, d=1, e=1, and the degradation reactions of other a, b, c, d, and e functional combinations are similar and fall within the protection scope of the present invention.

[0217] Further, in step A, the initial polymer contains -R1NHCOOR2- units; the degradation agent includes a compound R3(OH)n having a hydroxyl group; and the degradation reaction includes the following reaction:

[0218] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0219] Further, in step C, the chain extension group of the grafting agent includes an unsaturated double bond, and the grafting group of the grafting agent includes a carboxyl group or an anhydride group; and the grafting reaction includes the following reaction:

[0220] -R1NHCOOR3(OH) (n-1) -+-R2OH+R4-(C=C) a -(CR5) b -(COOH)m→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4+R2-O-(CO)-(CR5) b -(C=C) a -R4+H2O

[0221] or

[0222] -R1NHCOOR3(OH) (n-1) -+-R2OH+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4-+-R2-O-(CO)-(CR5) b -(C=C) a -R4-

[0223] Wherein, -R2OH+R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents with grafting groups, and the grafting groups include carboxyl -(COOH)m or acid anhydride groups -(CO)O(CO)-. Preferably, a=1-6, which is the functionality of the unsaturated double bond functional group -(C=C)a- of the grafting agent. More preferably, b=0-6, which is the number of carbon atoms from the unsaturated double bond to the grafting group. -R4- and R5 are side groups of the grafting agent main chain, including H atoms, methyl groups and other organic groups. The grafting agent includes acrylates, methacrylates, acids with unsaturated double bonds, acid anhydrides or carboxylates.

[0224] Further, in step A, the initial polymer contains -R1NHCOOR2- units; the degradation agent includes an acid, anhydride or anhydride salt with an unsaturated double bond; and the degradation reaction includes the following reaction:

[0225] -R1NHCOOR2—+R4-(C=C) a -(CR5) b -(COOH)m→R1-NH-(CO)-(CR5)b -(C=C) a -R4+R2-O-(CO)-(CR5) b -(C=C) a -R4+CO2

[0226] or

[0227] -R1NHCOOR2—+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→-R1NH-(CO)-(CR5) b -(C=C) a -R4-+-R2-O-(CO)-(CR5) b -(C=C) a -R4-+CO2

[0228] Wherein, R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents with grafting groups, the grafting groups include carboxyl -(COOH)m or acid anhydride group -(CO)O(CO)-, a=1~6, which is the functionality of the unsaturated double bond functional group -(C=C)a- of the grafting agent, b=0~6, which is the number of carbon atoms from the unsaturated double bond to the grafting group, -R4- and R5 are side groups of the grafting agent main chain, including H atoms, methyl groups and other organic groups. The grafting agents include acrylates, maleic anhydride and esters, acids, anhydrides or carboxylates with unsaturated double bonds;

[0229] Further, in step C, when the initial polymer contains -R1NHCOOR2- units; the grafting agent includes an acid, anhydride or anhydride salt with an unsaturated double bond; the grafting reaction also includes an amide condensation reaction, including the following reaction:

[0230] -R-NH-R'+R4-(C=C) a -(CR5) b -(COOH)m→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0231] or

[0232] -R-NH-R'+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0233] Among them, R4-(C=C)a-(CR5)b-(COOH)m and R4-(C=C)a-(CR5)b-(CO)O(CO)- are grafting agents with grafting groups, including carboxyl-(COOH)m or acid anhydride-(CO)O(CO)-, a=1~6, which is the functionality of the unsaturated double bond functional group-(C=C)a- of the grafting agent, b=0~6, which is the number of carbon atoms from the unsaturated double bond to the grafting group, —RN-R' is an amine-containing compound, R is the main chain, and R' is a side group connected to the N atom, including H atom, methyl and other organic groups. The grafting agent includes acrylate, maleic anhydride, ester with unsaturated double bond, acid, anhydride or carboxylate; the amide condensation reaction can make the grafting group react with hydroxyl and amine at the same time, so that the amino compound and polyol do not need to be separated and purified for the resin intermediate.

[0234] On the other hand, the present invention claims a modified polymer prepared by any of the above-mentioned methods through grafting reaction treatment.

[0235] The present invention also provides a method for preparing a modified polymer of a semi-cured material by mixing and treating the modified resin prepared by any of the above methods, wherein the modified polymer is obtained by treating the initial polymer, and the treatment comprises the following steps:

[0236] F: Add a curing agent to the modified polymer and mix them to obtain a semi-cured material.

[0237] Furthermore, the curing agent is a compound that can react with the chain extending group, or a compound that can induce the chain extending group to react with each other. Further, the reactive functional group of the compound that reacts includes one or a combination of free radical initiator, isocyanate group, acid anhydride, carboxyl group, epoxy group, amine group, amide group or aldehyde.

[0238] Furthermore, in step A, the initial polymer is polyurethane, including thermoplastic polyurethane TPU with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The initial polymer molecular chain carries chain-breaking groups, including -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, The degradation reaction includes one or more combinations of alcoholysis, alkaline hydrolysis, hydrolysis, aminolysis, thermal decomposition or acidolysis; further, the degradation agent includes one or more combinations of polyols, alkaline solutions, water, ammonia water, acids, acid anhydrides, carboxylates, polar and non-polar solvents;

[0239] Preferably, in step C, the grafting group includes one or more combinations of amide groups, amine groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, acid anhydrides, carboxylates or epoxy groups, and the chain extension group includes one or more combinations of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, unsaturated double bonds, ester groups, epoxy groups or aldehydes.

[0240] Preferably, in step C, the chain extending group comprises an unsaturated double bond.

[0241] Preferably, in step 1, the curing agent includes a thermosensitive curing agent, the thermosensitive curing agent includes a thermosensitive free radical initiator and a blocked isocyanate, and the thermosensitive free radical initiator includes a peroxide, a persulfide, a peroxycarbonate, a peroxyboric acid, an azo compound or other suitable free radical initiator that can initiate the curing of a double bond-containing compound.

[0242] More preferably, the free radical initiator includes tert-butyl peroxyisopropyl carbonate, methyl ethyl ketone peroxide, potassium persulfate, cumene hydroperoxide, dibenzoyl peroxide, tert-butyl perbenzoate or 2,4-di-tert-butyl peroxide isopropylbenzene.

[0243] Furthermore, in step 1, a step of heating the modified polymer is included, wherein the modified resin is heated to 50° C. to 180° C., and then a curing agent is added, thereby reducing its viscosity and making the resin and the curing agent uniformly mixed.

[0244] Furthermore, the method further comprises the step of:

[0245] G: The semi-cured material obtained in step 1 is heated to 50-160°C and impregnated with fibers and / or fillers to produce a reinforced or filled semi-cured material, wherein the fiber form includes one or a combination of fiber fabric, continuous fiber yarn, chopped fiber, ball fiber, powdered fiber, and filler. Filling the reinforcing material (i.e., fiber) and filler with the modified polymer under heating conditions can help improve the impregnation quality of the reinforcing material with the modified polymer. The process of impregnating the fiber and filler includes: one or a combination of high-speed stirring, centrifugal stirring, screw mixing, rubber roller kneading, stirring and kneading, forming a rubber film composite roll pressing, diluting and then impregnating, and composite and then rolling.

[0246] The non-reinforced semi-cured material can be used to make films for bonding plates, sheets, honeycombs, foams and other materials. The semi-cured material containing reinforcing or filling materials obtained in step G includes composite prepreg, sheet molding compound SMC, and bulk molding compound BMC. The manufacturing process method used can be selected from composite prepreg, sheet molding compound SMC, and bulk molding compound BMC manufacturing equipment and process, and reference can be made to "Composite Material Forming Technology and Application" (edited by Xu Zhu, National Defense Industry Press). The fiber materials used include metal fibers, non-metallic fibers, polymer fibers and natural fibers, including steel fibers, aluminum fibers, copper fibers, glass fibers, basalt fibers, ceramic fibers, alumina fibers, carbon fibers, polyester fibers, nylon fibers, polyvinyl alcohol fibers, ultra-high molecular weight polyethylene fibers, polypropylene fibers, spandex, bamboo fibers, hemp fibers, palm fibers, cotton fibers, and silk. Preferably, the weight ratio of fiber to modified resin is 0-0.1:1, 0.1-0.25:1, 0.25-0.4:1, 0.4-0.8:1, 0.8-1:1, 1.5:1, 1.5-2:1, 2-3:1, 3-4:1, 4-6:1 or 6-8:1; the semi-cured material obtained in step g of the present invention can further enhance its mechanical properties, and can be used to manufacture composite materials according to traditional composite material semi-cured material molding processes and equipment, including prepreg composite material manufacturing processes, sheet molding compound composite material manufacturing processes, and bulk molding compound composite material manufacturing processes. In addition, molding processes including hand lay-up, injection, vacuum infusion, RTM, winding, pultrusion, compression molding, continuous plate, etc. can be used, and the molding pressure is 0.05-0.1MPa, 0.1-0.5MPa, 0.5-1MPa, 1-2MPa, 2-5MPa, 5-10MPa, 10-20MPa, 20-30MPa or 30-50MPa.

[0247] Furthermore, in step H or step G, a cooling step is included, wherein the semi-cured material is cooled to below 50° C. for storage, preferably, cooled to below 35° C. for storage.

[0248] On the other hand, the present invention claims a modified polymer prepared as a semi-cured material by any of the above-mentioned mixing methods.

[0249] As another embodiment, the present invention also provides a method for preparing a modified polymer of a cured resin by curing reaction treatment based on any one of the above methods and the modified resin or semi-cured material prepared, wherein the modified polymer is obtained by treating the initial polymer, and the treatment comprises the following steps:

[0250] Step e, impregnating the modified polymer into fibers at 0-150° C. to produce a composite material, wherein the fibers include one or a combination of fiber fabrics, continuous fiber yarns, chopped fibers, ball-shaped fibers, powdered fibers or fillers.

[0251] F: Add a curing agent to the composite material to carry out a curing reaction to obtain a cured resin.

[0252] Furthermore, the curing agent is a compound that can react with the chain extension group, or a compound that can trigger the chain extension group to react with each other. Furthermore, the curing agent molecule contains at least two or more chain extension group reaction functional groups to achieve the function of chain extension and curing of the modified polymer molecular chain. Chain extension group reaction functional groups include but are not limited to free radical initiators, isocyanate groups, acid anhydrides, carboxyl groups, epoxy groups, amine groups, and amide groups.

[0253] Furthermore, in step 1, the added curing agent also includes an accelerator compatible with the free radical initiator to promote the initiator to generate free radicals, and the accelerator includes a metal salt, an organic amine, including a cobalt salt, a copper salt, a zinc salt or an aniline accelerator. Adding an accelerator can reduce the initiation temperature of the initiator, improve the initiation efficiency of the initiator, and then achieve the curing of the modified resin at a low temperature or the rapid curing of the modified resin.

[0254] Preferably, in step 1, the curing agent includes a thermosensitive curing agent, the thermosensitive curing agent includes a thermosensitive free radical initiator and a blocked isocyanate, and the thermosensitive free radical initiator includes a peroxide, a persulfide, a peroxycarbonate, a peroxyboric acid, an azo compound or other suitable free radical initiator that can initiate the curing of a double bond-containing compound.

[0255] More preferably, the free radical initiator includes tert-butyl peroxyisopropyl carbonate, methyl ethyl ketone peroxide, potassium persulfate, cumene hydroperoxide, dibenzoyl peroxide, tert-butyl perbenzoate or 2,4-di-tert-butyl peroxide isopropylbenzene.

[0256] Furthermore, in step A, the initial polymer is a polyurethane, including thermoplastic polyurethane TPU with a linear or branched molecular structure and thermosetting polyurethane with a cross-linked network molecular structure. The main chain of the molecule contains a carbamate group, and the degradation agent contains a hydroxyl group. In the degradation reaction, the hydroxyl group reacts with the carbamate group and opens at least a portion of the carbamate bonds on the initial polymer molecular chain to generate a molecular chain fragment with a linear or branched molecular structure containing carbamate groups and / or hydroxyl groups. The initial polymer molecular chain carries a chain-breaking group, and the chain-breaking group includes -N(H)n-, -NH-(CO)-O-, -HN-(CO)-NH-, The degradation reaction includes one or more combinations of alcoholysis, alkaline hydrolysis, hydrolysis, aminolysis, thermal decomposition or acidolysis; the degradation agent includes one or more combinations of polyols, alkaline solutions, water, ammonia water, acids, anhydrides, carboxylates, polar and non-polar solvents;

[0257] Preferably, in step C, the grafting group includes one or more combinations of amide groups, amine groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, acid anhydrides, carboxylates or epoxy groups, and the chain extension group includes one or more combinations of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, unsaturated double bonds, ester groups, epoxy groups or aldehydes.

[0258] Preferably, in step A, the initial polymer is a polyurethane, the main molecular chain of which contains carbamate groups, and the degradation agent contains hydroxyl groups. In the degradation reaction, the hydroxyl groups react with the carbamate groups and open at least a portion of the carbamate bonds on the initial polymer molecular chain to generate molecular chain fragments with linear or branched molecular structures containing carbamate groups and / or hydroxyl groups.

[0259] Preferably, in step C, the chain extending group comprises an unsaturated double bond.

[0260] According to any of the above methods for obtaining a modified polymer resin by curing reaction, the present invention further provides the following preferred embodiments.

[0261] Further, the process of curing reaction is as follows:

[0262]

[0263] Further, the process of curing reaction is as follows:

[0264]

[0265] Among them, the grafting agent is D d NE e , A is the isocyanate group in the initial polyurethane, B is the hydroxyl group in the initial polyurethane, (AB) is the carbamate group in the initial polyurethane; X is the initial isocyanate main chain; Y is the initial polyol main chain; M is the degradation agent main chain; C is the active group of the degradation agent, including hydroxyl, active hydrogen, amine, and alkali metal groups; the chain-breaking group of the initial polyurethane is (AB); N is the main chain of the grafting agent, which can participate in the molecular morphology modification of the cured polyurethane resin; D is a grafting group, which can react with (AC) and B to generate (ACD) and (BD) so that the initial polymer molecular fragments in the resin intermediate are connected to the grafting agent molecules with the chain extender E; E is a chain extender group, which allows the initial polymer molecular fragments to be reconnected through the chain growth and / or cross-linking reaction of the chain extender group E to obtain a modified polymer; a, b, c, d, and e are functional groups, respectively.

[0266] As another embodiment, the process of the curing reaction is as follows:

[0267]

[0268] Among them, A is the isocyanate group in the initial polyurethane, B is the hydroxyl group in the initial polyurethane, (AB) is the carbamate group in the initial polyurethane; X is the initial isocyanate main chain; Y is the initial polyol main chain; M is the degradation agent main chain; C is the active group of the degradation agent, including hydroxyl, active hydrogen, amine, and alkali metal groups; Y(AB)(ba)X(AC)aM(a-c+1) is a carbamate polyol; Y(B)a is a recovered polyol; (AC) is the active end group generated by the active group of the degradation agent and one side of the carbamate group; D is a grafting group that can react with (AC) and B; E is a chain extension group that can extend or cross-link the polyurethane resin molecules to become a cured polyurethane resin; N is the main chain of the grafting agent, which can participate in the molecular morphology modification of the cured polyurethane resin; a, b, c, d, and e are functionalities, respectively.

[0269] Further, in step A, the following reaction is included:

[0270] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0271] Furthermore, in step C, the following reaction is included:

[0272] -R1NHCOOR3(OH) (n-1) -+-R2OH+R4-(C=C) a -(CR5) b -(COOH)m→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4+R2-O-(CO)-(CR5) b -(C=C) a -R4+H2O

[0273] or

[0274] -R1NHCOOR3(OH) (n-1) -+-R2OH+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→-R1NHCOOR3O-(CO)-(CR5) b -(C=C) a -R4-+-R2-O-(CO)-(CR5) b -(C=C) a -R4-

[0275] In step 1, the free radical initiator generates active free radicals to open the unsaturated double bonds to form free radicals to initiate a crosslinking curing reaction between the unsaturated double bonds.

[0276] Specifically, the following reactions are included:

[0277]

[0278] M1-OO-M2 is a peroxidation initiator, which generates free radicals under heating conditions or catalytic conditions of a promoter, and reacts with unsaturated double bonds to form chain growth points at the unsaturated double bonds.

[0279] In another embodiment, in step C, the initial polymer contains -R1NHCOOR2- units; the grafting agent includes esters, acids, anhydrides, and carboxylates with unsaturated double bonds; and the grafting reaction further includes an amide condensation reaction, including the following reaction:

[0280] --R-NH-R'+R4-(C=C) a -(CR5) b -(COOH)m→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0281] or

[0282] -R-NH-R'+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0283] Further, in step 1, the free radical initiator generates active free radicals to open the unsaturated double bonds to form free radicals to initiate a crosslinking and curing reaction between the unsaturated double bonds.

[0284] Specifically, the following reactions are included:

[0285]

[0286] M1-OO-M2 is a peroxidation initiator, which generates free radicals under heating conditions or catalytic conditions of a promoter, and reacts with unsaturated double bonds to form chain growth points at the unsaturated double bonds.

[0287] On the other hand, the present invention claims a modified polymer prepared by any of the above methods through a curing reaction treatment.

[0288] According to any one of the above methods for preparing a modified polymer, the present invention also provides the following preferred embodiments.

[0289] As a preferred embodiment, the resin intermediate, modified polymer, semi-cured material and cured resin do not contain isocyanate groups, so that the prepared resin intermediate, modified polymer, semi-cured material and cured resin can be stored for a long time and the toxicity of the product is reduced.

[0290] As a preferred embodiment, the curing agent does not contain a compound with an isocyanate group to prevent the semi-cured material from prematurely curing and hardening and the cured resin from foaming, thereby extending the process operation time. The production process operation time of the resin intermediate, the modified polymer, the semi-cured material and the cured resin is not less than 5 minutes, preferably, not less than 30 minutes, more preferably, not less than 2 hours, more preferably, not less than 4 hours, more preferably, not less than 8 hours, more preferably, not less than 12 hours, more preferably, not less than 24 hours.

[0291] As a preferred embodiment, the semi-cured material can be stored at 25°C for not less than 4 hours, preferably, not less than 24 hours, more preferably, not less than 3 days, more preferably, not less than 7 days, more preferably, not less than 21 days, more preferably, not less than 1 month, more preferably, not less than 2 months, more preferably, not less than 3 months, more preferably, not less than 6 months, more preferably, not less than 12 months.

[0292] As a preferred embodiment, step A further comprises the following steps:

[0293] B: removing and recovering the excess degradation agent in the resin intermediate obtained in step A. Further, the removal method includes one or more combinations of reduced pressure distillation, thin film evaporation, extraction purification, fractionation, rectification, precipitation, etc.

[0294] As a preferred embodiment, the step C further includes the following steps:

[0295] D: Filter, remove impurities and dry the modified resin obtained in step C. Further, the filtering method includes filter pressing and vacuum filtration; the impurity removal method includes one or more combinations of extraction purification, fractionation, rectification, precipitation, and the drying method includes one or more combinations of ultrasonic, microwave, heating, and vacuum-assisted drying methods.

[0296] As a preferred embodiment, in step A, the degradation reaction includes one or more of alcoholysis reaction, alcohol-alkali reaction, alkaline hydrolysis reaction, hydrolysis reaction, aminolysis reaction or pyrolysis reaction.

[0297] As a preferred embodiment, the degradation agent is an alcoholysis agent, and the alcoholysis agent includes a single molecule, an oligomer or a polymer with 1 to 6 hydroxyl groups.

[0298] As a preferred embodiment, the degradation agent is an alcoholysis agent which is a polyol with a functionality of 2 to 6 and a main chain containing 2 to 10 methylene groups.

[0299] As a preferred embodiment, the degradation agent is an alcoholysis agent which is a polyol with a functionality of 2-4, a main chain containing 2 to 6 methylene groups and an ether bond, which can improve the toughness of the polyurethane while maintaining its strength.

[0300] As a preferred embodiment, the degradation agent includes one or more selected from 1,2-propylene glycol, ethylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, 1,6-hexanediol, polyether polyols with a molecular weight of less than 700, or polyether polyols with a molecular weight of greater than 800. Preferably, the polyol is selected from ethylene glycol, diethylene glycol, dipropylene glycol, or glycerol, and has a molecular weight of 200 to 700 and a functionality of 2 to 4, so that a homogeneous resin intermediate can be obtained, and the resin intermediate does not need to be separated or purified, and can be used directly.

[0301] As a preferred embodiment, the active end groups in the resin intermediate include one or more of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, unsaturated double bonds, ester groups or epoxy groups.

[0302] As a preferred embodiment, the grafting agent contains unsaturated double bonds and compounds including but not limited to one or more of amide groups, amine groups, urea groups, amino groups, hydroxyl groups, carboxyl groups, acid anhydrides, and epoxy groups.

[0303] As a preferred embodiment, the free radical initiator includes but is not limited to a peroxide initiator and a promoter thereof.

[0304] As a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, and the cured polyurethanes comprise polyurethane waste.

[0305] As another preferred embodiment, the resin intermediate is compounded from different polymer resin intermediates made from different initial polymers.

[0306] Preferably, the initial polymer accounts for no less than 20% of the resin intermediate, more preferably no less than 40%, more preferably no less than 60%, more preferably no less than 70%, more preferably no less than 80%, which can reduce costs and improve the elongation at break of the modified resin.

[0307] As a preferred embodiment, the number average molecular weight of the resin intermediate measured by RID and VWD (254 nm) detectors is 150-200, 200-350, 350-700; 700-1000, 700-1000, 1000-1800, 1800-3000, 3000-5000, 5000-10000, 10000-30000 or 30000-60000 g / mol.

[0308] As a preferred embodiment, the hydroxyl value of the modified resin is 0-50, 50-100, 100-200, 200-500 or 500-800 mgKOH / g.

[0309] As a preferred embodiment, the acid value of the modified resin is 0-8, 8-16, 16-30, 30-100 or 100-200 mgkoH / g.

[0310] As a preferred embodiment, the amine value of the modified resin is 0-20, 20-40, 40-80 or 80-150 mgKOH / g.

[0311] As a preferred embodiment, the amine value of the resin intermediate is 0 to 20, 20 to 40, 40 to 80, 80 to 200 or 200 to 500 mg KOH / g

[0312] As a preferred embodiment, the resin intermediate or modified resin is measured by infrared spectrometer and has an absorption peak at 1680cm-1 to 1780cm-1 in the infrared spectrum, which can confirm that the resin intermediate or modified resin contains carbamate functional groups.

[0313] As a preferred embodiment, in the grafting reaction, the chain growth group of the grafting agent contains an unsaturated double bond, and the grafting group is selected from one or more of an amide group, a urea group, a hydroxyl group, a carboxyl group, an ester group, an anhydride group or an epoxy group. Because the unsaturated bonds can react with each other, no new polar groups will be introduced, and the initial polymer molecular chain will have little effect, and the adjustment of the modified polymer molecular chain is relatively easy to control. In addition, the unsaturated double bonds are initiated by an initiator, and the resin will not react at a temperature lower than the initiation temperature of the initiator, so that long-term storage and operation can be achieved. Once the initiation temperature of the initiator is reached, the resin can be quickly cured, and the curing efficiency of the resin can be improved.

[0314] As a preferred embodiment, in the grafting reaction, the grafting agent includes one or more selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, phthalic acid mono-2-(acryloyloxy)ethyl ester, phthalic acid mono-2-(methacryloyloxy)ethyl ester, N-(carboxyphenyl)maleimide, N-(carboxyphenyl)methacrylamide, N-(carboxyphenyl)acrylamide or methacryloyl chloride. These grafting groups can effectively react with the active terminal hydroxyl groups on the resin intermediate.

[0315] As a preferred embodiment, in the degradation reaction, the total mass of the degradation agent is 0.5-10 times that of the initial polymer. The degradation agent in this range can achieve the reaction without causing too much workload for the subsequent vacuum distillation.

[0316] As a preferred embodiment, the total mass of the unsaturated carboxylic acid or unsaturated carboxylic anhydride as the grafting agent is 0.2-10 times that of the polymer resin intermediate, so that a higher reaction yield can be achieved.

[0317] As a preferred embodiment, when the grafting agent reacts with the resin intermediate, the ratio of the total carboxylic acid-carboxylic acid anhydride moles of the unsaturated carboxylic acid or unsaturated carboxylic acid anhydride as the grafting agent to the hydroxyl moles of the resin intermediate is 0.8-1.2. In this case, the unsaturated carboxylic acid and the hydroxyl groups in the resin intermediate react completely, and there is no need to remove the excess acid or anhydride or carboxylate by reduced pressure distillation, which can reduce the process steps.

[0318] As a preferred embodiment, the modified resin is blended with a reactive diluent having an unsaturated double bond or an unsaturated resin. The reactive diluent includes one or more of styrene, methacrylate, hydroxyacrylate, polyol or acrylate, and the unsaturated resin includes unsaturated polyester resin, acrylic resin, vinyl resin, etc., wherein representative substances include but are not limited to methyl methacrylate, isobornyl methacrylate, isooctyl acrylate, cyclohexane acrylate, decyl methacrylate, 2-ethylhexyl methacrylate, dihydrocyclopentadiene acrylate, ethoxylated phenoxyethyl acrylate, hydroxypropyl methacrylate, ethylene glycol diacrylate, propylene glycol dimethacrylate, neopentyl glycol dimethacrylate, 1.6-hexanediol diacrylate, cyclohexane dimethacrylate, diallyl phthalate, diethylene glycol dimethacrylate, tripropylene glycol diacrylate, hydroxybutyl acrylate, pentaerythritol tetraacrylate, pentaerythritol trimethacrylate, glycerol triacrylate, trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate or glycerol diacrylate, etc., which can adjust the viscosity and performance of the modified resin.

[0319] As a preferred embodiment, it can be used for preparing composite materials by various other composite material processes, including pultrusion, winding, infusion, hand lay-up, spraying, RTM, etc.

[0320] As a preferred embodiment, the semi-cured material can be stored at 25°C for not less than 4 hours, preferably, not less than 24 hours, more preferably, not less than 3 days, more preferably, not less than 7 days, more preferably, not less than 21 days, more preferably, not less than 1 month, more preferably, not less than 2 months, more preferably, not less than 3 months, more preferably, not less than 6 months, more preferably, not less than 12 months.

[0321] As a preferred embodiment, the curing agent used to cure the modified resin includes a free radical initiator, and the free radical initiator includes but is not limited to a peroxide initiator and an accelerator thereof.

[0322] As a preferred embodiment, the initial polymer includes one or more cured polyurethanes. The cured polyurethane includes polyurethane waste, or different resins made from different initial polymers are compounded to form a modified resin. Preferably, the initial polymer accounts for no less than 20% of the modified resin, more preferably no less than 40%. More preferably, no less than 60%, more preferably, no less than 70%, which can reduce costs and improve the elongation at break of the modified resin.

[0323] As a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, and the cured polyurethanes comprise polyurethane waste.

[0324] As a preferred embodiment, the initial polymer resin has a wide range of sources. It can not only be prepared by direct solidification of black and white materials, but also can be taken from polyurethane waste, such as the commonly used insulation rigid foam in refrigerators and containers, polyurethane soft foam for mattresses and sofas, polyurethane elastomer screens for mines, polyurethane elastomer rollers, etc. The use of polyurethane waste not only reduces the cost of new polyurethane, but also increases the utilization value of polyurethane waste, which helps to improve the recycling level of polyurethane. The present invention is applied to the recycling of polyurethane, which can solve the key technical problems in the existing recycling of polyurethane. Because the existing polyurethane regeneration technology must make the initial polymer into standard chemical raw materials to make polyurethane that meets the performance requirements, it is necessary to adopt complex decomposition and purification steps, which are technically complex, energy-intensive, and cause by-product pollution. The present technology does not require these steps.

[0325] As a preferred embodiment, the tensile strength of the modified polymer is not less than 20 MPa, not less than 35 MPa, not less than 50 MPa, preferably, the tensile strength is not less than 60 MPa, and more preferably, the tensile strength is not less than 70 MPa.

[0326] As a preferred embodiment, the modified polymer has a flexural strength of not less than 30 MPa, not less than 45 MPa, preferably, not less than 55 MPa, more preferably, a flexural strength of not less than 65 MPa, more preferably, a flexural strength of not less than 75 MPa, more preferably, a flexural strength of not less than 85 MPa, more preferably, a flexural strength of not less than 95 MPa, more preferably, a flexural strength of not less than 105 MPa, more preferably, a flexural strength of not less than 120 MPa.

[0327] As a preferred embodiment, the elongation at break of the modified polymer is not less than 2%, preferably, the elongation at break is not less than 3%, more preferably, the elongation at break is not less than 4%, more preferably, the elongation at break is not less than 5%, more preferably, the elongation at break is not less than 20%, more preferably, the elongation at break is not less than 50%, more preferably, the elongation at break is not less than 100%, more preferably, the elongation at break is not less than 150%.

[0328] As a preferred embodiment, the heating method used in the degradation reaction and / or grafting reaction includes microwave heating, ultrasonic heating, and electromagnetic heating. Preferably, in the microwave heating reaction, a microwave absorbing material is added to the reaction material, and the microwave absorbing material includes ferrite powder, carbonyl iron powder, silicon carbide powder, silicon carbide fiber, and composite ferrite, which will quickly convert microwaves into heat energy during microwave heating to improve the reaction efficiency.

[0329] As a preferred embodiment, the degradation reaction and / or grafting reaction is carried out using a microchannel reactor, which can improve the reaction efficiency and reduce the reaction safety risk.

[0330] In another aspect, the present invention claims a modified polymer resin prepared by any one of the above methods.

[0331] The present invention has found that only a portion of the energy of the polymer in the existing method is needed to open a portion of the polymer molecular chain to convert it into a polymer-modified resin, and then the modified resin is cured to become a modified polymer. In this process, the molecular weight and molecular structure of the initial polymer are adjusted to meet the requirements of the use environment for polymer performance.

[0332] The invention provides a modified polymer. By designing and adjusting the chemical reactions in each manufacturing step, a cured initial polymer is reacted with a degradation agent to prepare a resin intermediate with an active terminal group. A reactant and a crosslinking group, specifically an unsaturated carboxylic acid or an unsaturated carboxylic anhydride as a grafting agent, are introduced to react with the active terminal group to prepare a modified polymer with a chain extension or crosslinking reaction group, i.e., an unsaturated double bond. A free radical initiator is added to initiate the mutual reaction of unsaturated double bonds in the modified polymer to cause molecular chain extension and crosslinking curing reaction to obtain a cured polyurethane resin. The use of isocyanate to directly participate in the reaction to manufacture polyurethane is reduced and avoided, and the water sensitivity and high activity of the isocyanate group to cause the resin to foam and gel prematurely is avoided, so that the resin has a longer process operation time, and the modified polymer can adapt to the traditional composite material processing technology, while the existing polyurethane resin requires complex equipment assistance to manufacture the composite material; and the invention can also optimize the molecular structure of the initial polymer, so that the comprehensive mechanical properties of the cured polyurethane resin can also be significantly improved.

[0333] The invention discloses a modified polyurethane resin, a modified epoxy resin, a modified vinyl resin, a modified unsaturated resin and a preparation method thereof, as well as an application of the modified polyurethane resin in improving the toughness of a modified thermosetting resin product prepared by using the modified polyurethane resin. The invention comprises the following steps: subjecting an initial polyurethane to a degradation reaction with a degradation agent having an active group, breaking at least a part of the molecular chain of the initial polyurethane, and obtaining a resin intermediate containing active hydrogen and having an initial polyurethane molecular fragment, or further converting the resin intermediate containing active hydrogen into a resin intermediate containing an initial polyurethane molecular fragment having a chain extension group through a grafting reaction; further esterifying the resin intermediate to obtain an unsaturated modified polyurethane resin containing an active terminal double bond; as a resin toughening modifier component, the unsaturated modified polyurethane resin can effectively improve the toughness of a thermosetting resin, for example, when added to a liquid thermosetting resin in a certain proportion to participate in curing together, the addition of the unsaturated modified polyurethane resin can significantly improve the toughness of the thermosetting resin, and thus in fact plays the role of a thermosetting resin toughening agent. The unsaturated modified polyurethane resin of the present invention is a derivative of a degraded polyurethane product obtained by chemical recycling of polyurethane solid waste as a toughening modifier, and the toughening modifier can be added to thermosetting resin systems such as vinyl, unsaturated resin, epoxy resin, etc., that is, the toughness of these cured resins can be improved.

[0334] The present invention provides a new toughening agent system in an innovative way, which can be introduced into the thermosetting resin system in a certain proportion by direct addition, achieving the toughening effect without affecting other properties of the cured resin, such as heat resistance and mechanical strength, effectively overcoming the pain points of the existing toughening agent system and meeting the needs of the industry. And the obtained toughened resin has similar application scenarios as conventional thermosetting resins, including but not limited to the preparation of various composite materials such as blade parts, window frames, frames, various pultruded profiles, cable boxes, sucker rods, various parts of automobiles and ships, sports and leisure products, etc. through infusion, pultrusion, winding, spraying, RTM, hand lay-up, prepreg, SMC / BMC and other process methods. DETAILED DESCRIPTION

[0335] The detailed features and advantages of the present invention are described in detail in the specific implementation modes below, and the contents are sufficient to enable any person skilled in the art to understand the technical contents of the present invention and implement them accordingly. Moreover, according to the description and claims disclosed in this specification, those skilled in the art can easily understand the relevant objects and advantages of the present invention.

[0336] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0337] The raw materials used in this embodiment can be purchased on the market. Among them, liquid nitrile rubber DY-065 is purchased from Guangzhou Weilina Chemical Co., Ltd.; epoxy resin 127 and epoxy resin 128 are purchased from Nanya Chemical; cobalt water accelerator HL-88B and methyl ethyl ketone peroxide MEKP are purchased from Guangzhou Hongli Chemical; unsaturated resin uses 191 type o-phthalic polyester resin, and vinyl resin uses the most commonly used bisphenol A type 901 resin; various anhydrides and amine curing agents are purchased from Alibaba website; other reagents are purchased from Sinopharm or Alibaba website.

[0338] The present invention provides a method for preparing a toughening aid, comprising the following steps:

[0339] Step A: subjecting the initial polyurethane to a degradation reaction with a degradation agent having an active group, breaking at least a portion of the molecular chain of the initial polyurethane, and obtaining a resin intermediate containing a molecular fragment of the initial polyurethane and the active group;

[0340] Wherein, the initial polyurethane comprises a thermoplastic polyurethane having a linear or branched molecular structure and a thermosetting polyurethane having a cross-linked network molecular structure, and the molecular weight of the initial polyurethane is not less than 10000 g / mol;

[0341] Step C: reacting the resin intermediate with a grafting agent having a grafting group to prepare a modified polyurethane resin containing an initial polymer molecular chain fragment having a chain extension group; the grafting reaction is an acylation reaction and / or an esterification reaction.

[0342] The detailed test process and results of Examples A1, L1 and L2 are given below for exemplary illustration:

[0343] Embodiment A1:

[0344] Step 1: Mix 300 grams of polyurethane waste (post-consumer container rigid foam) and 600 grams of ethylene glycol, add 0.3 grams of catalyst tetrabutyl titanate, and heat and stir until the polyurethane solid is dissolved to perform a degradation reaction, wherein the temperature is maintained in the range of 190°C (170°C-220°C) to obtain a degradation reaction liquid.

[0345] Step 2: After the degradation reaction liquid is cooled to 120° C., the undegraded solid residue is separated and filtered, and the filtrate is subjected to reduced pressure distillation to remove excess ethylene glycol to obtain a polyol product A1. The hydroxyl value of the obtained polyol product A1 is 450 mgKOH / g, which is determined according to ASTM E1899-2016.

[0346] Step 3: Take 100 g of the polyol product A1, add 80 g of succinic anhydride, 2 g of catalyst p-toluenesulfonic acid and 200 ml of dimethyl sulfoxide, carry out a ring-opening reaction at 120° C. for 6 hours, and remove the solvent dimethyl sulfoxide by reduced pressure distillation to obtain the target product toughening agent S1.

[0347] Embodiment L1:

[0348] Step L1: Take 100 grams of polyurethane waste (post-consumer refrigerator hard foam) and 25 grams of polyurethane waste (post-consumer polyurethane mattress foam material) into a round-bottom flask, mix with 150 grams of diethylene glycol, add 0.1 grams of catalyst tetrabutyl titanate, and mechanically stir until the polyurethane solid is completely dissolved to carry out degradation reaction, wherein the temperature is maintained in the range of 230°C (210°C-240°C) for 2 hours to obtain a degradation reaction liquid.

[0349] Step L2: After the degradation reaction liquid is cooled to 120°C, it is filtered and separated to remove the undegraded solid residue. The filtrate is distilled under reduced pressure to remove excess diethylene glycol to obtain a resin intermediate containing active hydrogen. The resin intermediate, 120 g of methacryloyl chloride, 600 ml of dichloromethane and 100 g of triethylamine are added to a round-bottom flask, and 0.5 g of hydroquinone is added. The mixture is stirred at 0°C for 3 hours, and then naturally heated to 25°C and continued to be stirred for 12 hours. After filtering, the liquid is removed by rotary evaporation, and then the mixture is redissolved in 600 ml of dichloromethane, and washed three times with 80 ml of 10% sodium carbonate aqueous solution and saturated brine respectively. The organic layer is dried over anhydrous sodium sulfate for 3 hours, filtered again, and the solvent is removed by rotary evaporation of the filtrate to obtain an unsaturated modified polyurethane resin containing an active terminal methacrylate bond.

[0350] Embodiment L2:

[0351] Step L1: 80 g of polyurethane waste (post-consumer polyurethane soft foam material), 200 g of polyurethane waste (post-consumer container rigid foam) and 700 g of ethylene glycol are mixed, and then heated and stirred until the polyurethane solid is dissolved to perform a degradation reaction, wherein the temperature is maintained in the range of 190° C. (160° C.-210° C.) to obtain a degradation reaction liquid.

[0352] Step L2: Cool the degradation reaction liquid to 50°C, and then filter and separate to remove the undegraded solid residue. Add 20 grams of phthalic anhydride and 35 grams of maleic anhydride to the obtained filtrate, stir for 3 hours, and then gradually heat up to 165°C and maintain for 1 hour while continuing to stir; after stopping the reaction, cool to room temperature, transfer the reaction mixture and remove excess ethylene glycol by vacuum distillation to obtain a resin intermediate after the grafting reaction, add the resin intermediate and 500 grams of acrylic acid into a round-bottom flask, add 0.8 grams of hydroquinone, stir at 140°C for 1.5 hours, and keep bubbling with nitrogen, blow out the generated water vapor from the condenser at the upper end of the flask, cool to 90°C, and vacuum distill to obtain an unsaturated modified polyurethane resin containing active terminal acrylate bonds.

[0353] The present invention further provides a method for preparing an epoxy resin with improved toughness by using such an unsaturated modified polyurethane resin as a toughening modifier, comprising the following steps:

[0354] Step 1: epoxy resin, anhydride curing agent, toughening agent, catalyst, DMP-30 and other raw materials are mixed evenly to obtain a mixture;

[0355] Step 2: pouring the mixture into a flat mold and then placing it in an oven for heating and curing, wherein the heating and curing is carried out under the following conditions: heating to 150°C at a rate of 80°C / 0.5 hour and maintaining at 150°C for 2 hours;

[0356] Step 3: Turn off the oven heating and allow the heated and cured mixture to cool naturally to room temperature (25° C.) to obtain a cured resin plate (toughened cured epoxy resin).

[0357] The detailed test process and results of Examples 1 to 3 and Comparative Examples 1 to 3 are given below for exemplary description:

[0358] Example 1

[0359] 108 g of epoxy resin (Nan Ya 127), 100 g of methyltetrahydrophthalic anhydride (i.e., anhydride curing agent), 10 g of unsaturated modified polyurethane resin L1, 0.5 g of tert-butyl perbenzoate and 2 g of catalyst DMP-30 were mixed uniformly to obtain a mixture; the mixture was cured according to steps 1, 2 and 3 to obtain a cured resin plate (epoxy resin with improved toughness).

[0360] Example 2

[0361] 122 g of epoxy resin (Nan Ya 127), 100 g of phthalic anhydride (i.e., anhydride curing agent), 15 g of unsaturated modified polyurethane resin L2, 0.8 g of tert-butyl perbenzoate and 2 g of catalyst DMP-30 are mixed evenly to obtain a mixture; the mixture is cured according to steps 1, 2 and 3 to obtain a cured resin plate (epoxy resin with improved toughness).

[0362] Example 3

[0363] 112 g of epoxy resin, 100 g of methyltetrahydrophthalic anhydride (i.e., anhydride curing agent), 10 g of toughening agent S1 and 2 g of catalyst DMP-30 were mixed evenly to obtain a mixture; the mixture was cured according to steps C, D and E to obtain a cured resin plate (modified epoxy resin).

[0364] Comparative Example 1

[0365] 108 g of epoxy resin (Nan Ya 127), 100 g of methyltetrahydrophthalic anhydride (i.e., anhydride curing agent) and 2 g of catalyst DMP-30 were mixed evenly to obtain a mixture; the mixture was cured according to steps 1, 2 and 3 to obtain a cured resin plate (cured epoxy resin).

[0366] Comparative Example 2

[0367] 122 g of epoxy resin (Nan Ya 127), 100 g of phthalic anhydride (i.e., anhydride curing agent) and 2 g of catalyst DMP-30 were mixed evenly to obtain a mixture; the mixture was cured according to steps 1, 2 and 3 to obtain a cured resin plate (cured epoxy resin).

[0368] Comparative Example 3

[0369] 108 g of epoxy resin (Nan Ya 127), 100 g of methyltetrahydrophthalic anhydride (i.e., anhydride curing agent), 20 g of toughening agent (liquid nitrile rubber DY-065) and 2 g of catalyst DMP-30 are mixed evenly to obtain a mixture; the mixture is cured according to steps b, c and d to obtain a cured resin plate (toughened cured epoxy resin).

[0370] The cured resin plates obtained in Examples 1 to 2 and Comparative Examples 1 to 3 were tested according to the impact performance test standard ASTM D4812, and the DSC Tg was tested according to the glass transition temperature test standard ASTM D7426. The test results are shown in Table 1.

[0371] Table 1: Properties of cured resin plates of Examples 1 to 3 and Comparative Examples 1 to 3

[0372] sample Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 DSC Tg℃ 137 150 139 135 151 114 Impact strength (KJ / m2) 35 30 33 21 17 31

[0373] As can be seen from Table 1, since Examples 1 to 3 add such unsaturated modified polyurethane resin as toughening modifier, the impact strength of the modified epoxy resin obtained is greatly improved, indicating that its toughness has been significantly improved; but at the same time, the glass transition temperature Tg of Examples 1 to 3 and Comparative Examples 1 to 2 changes very little or even slightly increases, indicating that its heat resistance does not decrease due to the change of the toughening system of the present invention. Therefore, the modified epoxy resin obtained by the toughening additive of the present invention can effectively solve the disadvantage that the traditional toughening agent will reduce the physical properties of the toughened material.

[0374] The present invention further provides a method for obtaining a modified thermosetting resin product by heating and curing with an amine curing agent. The detailed test process and results of Examples 4 to 5 and Comparative Examples 4 to 7 are given below for exemplary description:

[0375] Example 4

[0376] 100 g of epoxy resin (Nan Ya 128), 24 g of isophorone diamine (i.e., amine curing agent), 4 g of toughening modifier L1, 4 g of toughening modifier L2, and 0.5 g of tert-butyl perbenzoate are mixed together to obtain a mixture; the mixture is first placed at room temperature for 0.5 hour, then at 60° C. for 2 hours, and then the temperature is raised to 80° C. and maintained for 6 hours; after curing, a cured resin plate (epoxy resin with improved toughness) is obtained.

[0377] Comparative Example 4

[0378] 100 g of epoxy resin (Nan Ya 128) and 24 g of isophorone diamine (i.e., amine curing agent) were mixed together to obtain a mixture; the mixture was first placed at room temperature for 0.5 hour, then at 60° C. for 2 hours, and then heated to 80° C. and maintained for 6 hours; after curing, a cured resin plate (cured epoxy resin) was obtained.

[0379] Comparative Example 5

[0380] 100 g of epoxy resin (Nan Ya 128), 24 g of isophorone diamine and 10 g of toughening agent (liquid nitrile rubber DY-065) were mixed together to obtain a mixture; the mixture was first placed at room temperature for 0.5 hour, then at 60° C. for 2 hours, and then heated to 80° C. and maintained for 6 hours; after curing, a cured resin plate (toughened cured epoxy resin) was obtained.

[0381] Table 2: Properties of cured resin plates of Example 4 and Comparative Examples 4-5

[0382] sample Example 4 Comparative Example 4 Comparative Example 5 DSC Tg℃ 93 95 75 Impact strength (KJ / m2) 39 23 36

[0383] Comparative Example 6

[0384] 100 g of epoxy resin (Nan Ya 128) and 40 g of butanone were mixed and stirred into a uniform solution, and then 4 g of dicyandiamide and 0.1 g of 2-methylimidazole were added, and stirred vigorously to obtain a uniform mixture; the mixture was poured into a horizontally placed flat plate mold, placed in an oven and heated to 140°C and maintained for 30 minutes; after curing, a cured resin plate (cured epoxy resin) was obtained.

[0385] Comparative Example 7

[0386] 100 g of epoxy resin (Nan Ya 128), 8 g of toughening agent (liquid nitrile rubber DY-065) and 40 g of butanone were mixed and stirred into a uniform solution, and then 4 g of dicyandiamide and 0.1 g of 2-methylimidazole were added, and stirred vigorously to obtain a uniform mixture; the mixture was poured into a horizontally placed flat plate mold, placed in an oven and heated to 140° C. and maintained for 30 minutes; after curing, a cured resin plate (toughened and cured epoxy resin) was obtained.

[0387] Example 5

[0388] 100 g of epoxy resin (Nan Ya 128), 7 g of toughening modifier L1, 10 g of toughening modifier L2, 0.8 g of tert-butyl perbenzoate and 40 g of butanone were mixed and stirred into a uniform solution, and then 4 g of dicyandiamide and 0.1 g of 2-methylimidazole were added, and the mixture was vigorously stirred to obtain a uniform mixture; the mixture was poured into a horizontally placed flat plate mold, placed in an oven and heated to 140° C. and maintained for 30 minutes; after curing, a cured resin plate (epoxy resin with improved toughness) was obtained.

[0389] Table 3: Properties of cured resin plates of Example 5 and Comparative Examples 6-7

[0390]

[0391] Table 2 and Table 3 represent different epoxy curing systems. It can be seen from Table 2 and Table 3 that the impact strength of the modified epoxy resin obtained by adding toughening aids in Examples 4-5 is greatly improved, indicating that its toughness has been significantly improved; but at the same time, the glass transition temperature Tg of Examples 4-5 is very small compared with that of Comparative Examples 4 and 6, indicating that its heat resistance will not decrease due to the change of the toughening system of the present invention. In contrast, although the addition of conventional toughening agents to Comparative Examples 5 and 7 will appropriately improve toughness, the glass transition temperature Tg will be significantly reduced. Therefore, the modified epoxy resin obtained by the toughening aid of the present invention can effectively solve the disadvantage that traditional toughening agents will reduce other physical properties of the toughened material.

[0392] The present invention further provides a method for preparing other types of thermosetting resins with improved toughness by using such novel unsaturated modified polyurethane resin as a toughening modifier, such as vinyl resin, unsaturated resin, phenolic resin and the like, which can effectively improve the toughness of such thermosetting resins after curing without reducing other properties. The detailed test process and results of Examples 6 to 7 and Comparative Examples 8 to 9 are given below for exemplary explanation:

[0393] Comparative Example 8

[0394] 100 g of orthophthalic unsaturated resin 191, 1.5 g of MEKP and 1 g of cobalt water accelerator HL-88B were added and stirred to form a uniform solution, which was allowed to stand at room temperature for 16 hours and then placed in an oven at 80°C for 4 hours to obtain a cured resin plate.

[0395] Comparative Example 9

[0396] 100 g of vinyl resin 901 was added with 1.5 g of MEKP and 1 g of cobalt water accelerator HL-88B, and the mixture was stirred to form a uniform solution. The solution was allowed to stand at room temperature for 16 hours, and then placed in an oven at 80°C for 4 hours to obtain a cured resin plate.

[0397] Example 6

[0398] 100 g of orthophthalic unsaturated resin 191, 1.6 g of MEKP, 1 g of cobalt water accelerator HL-88B, and 10 g of toughening modifier L1 were added and stirred to form a uniform solution, allowed to stand at room temperature for 16 hours, and then placed in an oven at 80°C for 4 hours to obtain a cured resin plate (unsaturated resin plate with improved toughness).

[0399] Example 7

[0400] 100 g of vinyl resin 901 was added with 1.6 g of MEKP, 1 g of cobalt water accelerator HL-88B, 4 g of toughening modifier L1 and 6 g of toughening modifier L2, and the mixture was stirred into a uniform solution. The solution was allowed to stand at room temperature for 16 hours, and then placed in an oven at 80°C for 4 hours to obtain a cured resin plate (vinyl resin plate with improved toughness).

[0401] Table 4: Properties of cured resin plates of Examples 6-7 and Comparative Examples 8-9

[0402] sample Test Standards Comparative Example 8 Comparative Example 9 Example 6 Example 7 DSC Tg℃ ASTM D7426 101 104 98 107 Impact strength (KJ / m2) ASTM D4812 15 19 27 34 Tensile strength MPa ASTM D638 70 81 69 85 Tensile modulus GPa ASTM D638 3.5 3.4 3.4 3.6 Tensile elongation at break % ASTM D638 2.3 4.9 5.4 5.6

[0403] It can be seen from Table 4 that the toughening aid of the present invention can also effectively improve the toughness of thermosetting vinyl resins and unsaturated resins without reducing other properties.

[0404] The terms and expressions used herein are for descriptive purposes only, and the present invention should not be limited to these terms and expressions. The use of these terms and expressions does not mean to exclude any equivalent features of the illustrations and descriptions (or parts thereof), and it should be recognized that various modifications that may exist should also be included in the scope of the claims. Other modifications, variations and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

[0405] Similarly, it should be pointed out that although the present invention has been described with reference to the current specific embodiments, ordinary technicians in this technical field should realize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions may be made without departing from the spirit of the present invention. Therefore, as long as the changes and modifications to the above embodiments are within the scope of the essential spirit of the present invention, they will fall within the scope of the claims of the present invention.

Claims

1. A method for preparing a modified polyurethane resin, characterized in that: The modified polyurethane is obtained by treating the initial polyurethane, and the treatment comprises the following steps: Step A: subjecting the initial polyurethane to a degradation reaction with a degradation agent having an active group, breaking at least a portion of the molecular chain of the initial polyurethane, and obtaining a resin intermediate containing a molecular fragment of the initial polyurethane and the active group; Wherein, the initial polyurethane comprises a thermoplastic polyurethane having a linear or branched molecular structure and a thermosetting polyurethane having a cross-linked network molecular structure, and the molecular weight of the initial polyurethane is not less than 10000 g / mol; Step C: reacting the resin intermediate with a grafting agent having a grafting group to prepare a modified polyurethane resin containing an initial polymer molecular chain fragment having a chain extension group; The grafting reaction includes one or more combinations of esterification, acylation, amide condensation or transesterification; The grafted group is one or more selected from amide group, urea group, hydroxyl group, carboxyl group, ester group, acid anhydride group or epoxy group.

2. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: In the step C, the grafting reaction is an acylation reaction and / or an esterification reaction.

3. The method for preparing a modified polyurethane resin according to claim 2, characterized in that: The modified polyurethane resin contains active terminal double bonds.

4. The method for preparing a modified polyurethane resin according to claim 2, characterized in that: In the step C, the acylation reaction and / or esterification reaction is a ring-opening reaction between the active hydrogen of the resin intermediate and the grafting agent containing the anhydride group; The grafting agent includes a cyclic acid anhydride, and the cyclic acid anhydride includes one or more combinations of monofunctional acid anhydride, bifunctional acid anhydride or free acid anhydride.

5. The method for preparing a modified polyurethane resin according to claim 4, characterized in that: The cyclic anhydride includes one or more combinations of succinic anhydride, maleic anhydride, phthalic anhydride, nadic anhydride, methylhexahydrophthalic anhydride, chlorendic anhydride, pyromellitic anhydride or trimellitic anhydride.

6. The method for preparing a modified polyurethane resin according to claim 2, characterized in that: The esterification reaction is an esterification reaction with acrylic acid and / or methacrylic acid, The grafting agent includes one or more selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, mono-2-(acryloyloxy)ethyl phthalate, mono-2-(methacryloyloxy)ethyl phthalate, N-(carboxyphenyl)maleimide, N-(carboxyphenyl)methacrylamide, N-(carboxyphenyl)acrylamide or methacryloyl chloride.

7. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: In the step A, the degradation reaction is an alcoholysis reaction, The degradation agent comprises a polyol, wherein the polyol comprises a diol and / or a high-functionality polyol, The diols include low molecular weight C2-C6 diols, The low molecular weight C2-C6 diol includes one or more combinations of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, diethylene glycol, dipropylene glycol, ethylene glycol ketone, propylene glycol ketone or neopentyl glycol. The high-functionality polyol includes glycerol, trimethylolethane, trimethylolpropane, pentaerythritol, sucrose polyol, sorbitol or polyether polyol. The temperature of the alcoholysis reaction is 110-150°C, 150-170°C, 170-180°C, 180-200°C, 200-220°C or 220-250°C. The alcoholysis reaction time is 0.5 to 2 hours, 2 to 3 hours, 3 to 6 hours, 6 to 12 hours, 12 to 24 hours, 24 to 48 hours or 48 to 64 hours.

8. A modified polyurethane resin prepared by the method for preparing a modified polyurethane resin according to any one of claims 1 to 7.

9. The modified polyurethane resin according to claim 8, characterized in that The modified polyurethane resin is used for manufacturing a modified thermosetting resin product prepared from the modified polyurethane resin and for improving the toughness of the modified thermosetting resin product prepared from the modified polyurethane resin.

10. The modified polyurethane resin according to claim 9, characterized in that The modified thermosetting resin product prepared by the modified polyurethane resin is prepared by blending the modified polyurethane resin with a thermosetting resin, and the thermosetting resin is an unsaturated resin, an epoxy resin or a vinyl resin.

11. Use of the modified polyurethane resin according to claim 8 in improving the toughness of a modified thermosetting resin product prepared from the modified polyurethane resin.

12. A method for preparing a modified epoxy resin using the modified polyurethane resin according to claim 8, characterized in that: The following steps are involved: Step A1: uniformly mixing the epoxy resin, the curing agent and the modified polyurethane resin to obtain an epoxy mixture; Step A2: heating and curing the epoxy mixture. Step A3: Cooling the epoxy mixture after heating and curing to obtain the modified epoxy resin.

13. The method for preparing a modified epoxy resin according to claim 12, characterized in that: The curing agent is a compound that can react with the chain extending group, or a compound that can induce the chain extending group to react with each other. The reactive functional groups of the compound to react include one or a combination of free radical initiators, isocyanate groups, acid anhydrides, carboxyl groups, epoxy groups, amine groups, amide groups or aldehydes; The curing agent also includes an accelerator compatible with the free radical initiator; The accelerator includes metal salts, organic amines, including cobalt salts, copper salts, zinc salts or aniline accelerators.

14. The method for preparing a modified epoxy resin according to claim 13, characterized in that: The curing agent contains anhydride or amine reactive functional groups; In the step A1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the epoxy mixture; In the step A2, the temperature of the heating and curing is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C. In the step A3, the epoxy mixture after heating and curing is cooled to below 50°C.

15. A modified epoxy resin prepared according to the method for preparing a modified epoxy resin according to claim 11, wherein the impact strength of the modified epoxy resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to that of the epoxy resin; and the tensile elongation at break of the modified epoxy resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to that of the epoxy resin.

16. A method for preparing a modified vinyl resin using the modified polyurethane resin according to claim 8, characterized in that: The following steps are involved: Step B1: uniformly mixing a vinyl resin, a free radical initiator, the modified polyurethane resin and an accelerator to obtain a resin mixture; Step B2: heating and curing the resin mixture. Step B3: Cooling the resin mixture after heating and curing to obtain the modified vinyl resin.

17. The method for preparing a modified vinyl resin according to claim 16, characterized in that: In the step B1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the resin mixture; In the step B2, the heating and curing temperature is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C. In the step B3, the resin mixture after heating and curing is cooled to below 50°C.

18. A modified vinyl resin obtained according to the method for preparing a modified vinyl resin according to claim 16, wherein the impact strength of the modified vinyl resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to that of the vinyl resin; and the tensile elongation at break of the modified vinyl resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to that of the vinyl resin.

19. A method for preparing a modified unsaturated resin using the modified polyurethane resin according to claim 8, characterized in that: The following steps are involved: Step C1: uniformly mixing an unsaturated resin, a free radical initiator, the modified polyurethane resin and an accelerator to obtain an unsaturated resin mixture; Step C2: heating and curing the unsaturated resin mixture, Step C3: Cooling the unsaturated resin mixture after heating and curing to obtain the modified unsaturated resin.

20. The method for preparing a modified unsaturated resin according to claim 19, characterized in that: In the step C1, the modified polyurethane resin accounts for 1-2%, 2-3%, 3-5%, 5-10%, 10-15%, 15-20%, 20-25%, 25-30%, 30-35% or 35-40% of the total weight of the unsaturated resin mixture; In the step C2, the temperature of the heating and curing is 10-60°C, 60-80°C, 80-100°C, 100-120°C, 120-130°C, 130-140°C, 140-160°C, 160-180°C or 180-200°C. In the step C3, the unsaturated resin mixture after heating and curing is cooled to below 50°C.

21. A modified unsaturated resin obtained by the method for preparing a modified unsaturated resin according to claim 18, wherein the impact strength of the modified unsaturated resin is increased by at least 20%, 30%, 40%, 50%, 60%, 70% or 80% relative to that of the unsaturated resin; and the tensile elongation at break of the modified unsaturated resin is increased by at least 8%, 15%, 20%, 30%, 40%, 50%, 75% or 100% relative to that of the unsaturated resin.

22. A composite material using the modified polyurethane resin according to claim 9 as a semi-cured material as a matrix.

23. The composite material according to claim 9 or 22, characterized in that The composite material is prepared by processes including but not limited to infusion, pultrusion, winding, spraying, RTM, hand lay-up, prepreg, SMC / BMC and the like.

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