Modified polyurethane resin, prepreg, composite material and preparation method thereof

Abstract

The invention discloses a modified polyurethane resin, a semi-cured material, a composite material and a preparation method of the modified polyurethane resin, the semi-cured material and the composite material. Part of an initial polyurethane molecular chain is opened to become a resin intermediate containing an initial polyurethane molecular fragment with an active group or a resin intermediate containing an initial polyurethane molecular fragment with a chain extension group; the preparation method comprises the following steps: preparing a resin intermediate, changing the resin intermediate into modified polyurethane containing an initial polyurethane molecular fragment with an active double-bond group through a grafting reaction, and curing the modified polyurethane into modified polyurethane resin, or mixing the modified polyurethane with reinforcing materials such as filler or fiber and the like to obtain the modified polyurethane resin. And curing to obtain the composite material based on the thermosetting modified polyurethane resin. In the process, the molecular weight and molecular structure of initial polyurethane are adjusted by designing and controlling chemical reaction, and modified polyurethane with target performance, a semi-cured material and a composite material based on the resin are obtained by designing and controlling additives.

Description

Technical Field

[0001] This patent relates to the field of polymer material technology, and involves a modified polyurethane resin, a semi-cured material, a composite material and a preparation method thereof. Background Art

[0002] "Progress in the Development of Raw Materials or Chemical Recycling of Waste Polymers" (Liu Chun. Nanjing Research Institute of Sinopec Yangzi Petrochemical Co., Ltd., Nanjing, 210048, Plastic Additives, Issue 4, 2020 (Total Issue 142)) introduces that the chemical recycling of polymers includes raw material recycling and chemical recycling. Raw material recycling is to turn waste plastics into petroleum raw materials for the production of petrochemicals or plastics. It usually does not cause the deterioration of the properties of chemicals or plastics, and there are no restrictions on their performance. Thermal recovery of raw materials uses high temperatures to break the chemical bonds of the polymer skeleton. This decomposition is called high-temperature degradation or thermal cracking when it is carried out in the absence of air, hydrogenation when it is carried out in a hydrogen atmosphere, and gasification in the presence of a controllable amount of oxygen. Depending on the change route, the quality and composition of the final product are also different. Chemical recycling is to convert polymers into monomers or monomer fragments through chemical reactions, and polymerize them again. The new polymer obtained is no different from the original polymer.

[0003] The disadvantages of chemical recycling of polymers are the changes in material composition, impurities involved, loss of mechanical properties due to degradation, lack of standardization and large changes in raw material supply. Even a single polymer (such as PE) has a wide melt index and a large variation in thermal stability. Before raw material or chemical recycling, it is necessary to separate waste plastics into single components, which is an indispensable process link, and then remove impurities.

[0004] Existing polymer recycling has problems such as high energy consumption, high cost, and by-product pollution caused by impurity removal and purification. Improvements are urgently needed to overcome the disadvantages of polymer recycling and obtain polymers that better meet production standards.

[0005] As a typical thermosetting polymer, polyurethane has the above-mentioned problems and difficulties in recycling. How to develop an efficient method to recycle polyurethane solid waste and convert it back into usable resin materials has a huge demand in the industry and has always been an area of ​​long-term concern in the industry. Summary of the invention

[0006] The present invention provides a modified polyurethane resin, a semi-cured material, a composite material and a preparation method thereof, which can solve the key problems of existing polyurethane solid waste recycling, namely, the problems of high energy consumption, high cost and by-product pollution caused by impurity removal and purification.

[0007] A method for preparing a modified polyurethane resin, 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 molecular fragments having the initial polyurethane and the active group; wherein the initial polyurethane includes 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;

[0009] 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.

[0010] Further, the initial polyurethane includes pure polyurethane and / or polyurethane composite;

[0011] The polyurethane composite contains fillers and / or fibers, wherein the fillers include solid or liquid additives that do not chemically react with the initial polyurethane.

[0012] Furthermore, the initial polyurethane includes at least one polyurethane waste that has lost its use function, or the resin intermediate is prepared by compounding a plurality of resin intermediates made from the initial polyurethane.

[0013] Furthermore, in the step A, the initial polyurethane comprises a thermoplastic polyurethane having a linear or branched molecular structure and / or a thermosetting polyurethane having a cross-linked network molecular structure.

[0014] Furthermore, the degradation reaction includes one or more combinations of pyrolysis, hydrolysis, alcoholysis, esterification, transesterification, aminolysis, acidolysis, alkaline hydrolysis, alcohol-alkali reaction, hydrogenolysis or acylation reaction.

[0015] Furthermore, in step A, the degradation agent carries the chain extension group having the chain extension or cross-linking function, and the chain extension group can react with other groups or itself to achieve molecular chain extension or cross-linking;

[0016] The grafted groups include one or more combinations of amide groups, amine groups, urea groups, hydroxyl groups, carboxyl groups, anhydride groups or epoxy groups.

[0017] The chain extension group includes one or more combinations of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, carboxyl groups, unsaturated double bonds, ester groups, epoxy groups or aldehyde groups.

[0018] Furthermore, the degradation agent contains at least one active group, and the active group includes a combination of 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.

[0019] Furthermore, the degradation agent is an alcoholysis agent, the degradation agent includes a polyol, and the polyol includes a diol and / or a high-functionality polyol; the alcoholysis reaction temperature 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 0.5-2h, 2-3h, 3-6h, 6-12h, 12-24h, 24-48h or 48-64h; the alcoholysis reaction yield is 50-60%, 60-70%, 70-80%, 80-95%, 95-100%; the number average molecular weight of the resin intermediate measured by two detectors, RID and VWD (254nm), is 150-200; 200-350; 350-7 00; 700-1000, 700-1000, 1000-1800, 1800-3000, 3000-5000, 5000-10000, 10000-30000 or 30000-60000 g / mol; the viscosity at room temperature (25°C) is 50-200 mPa·s, 200-500 mPa·s, 500- 1000mPa·s, 1000~2000mPa·s, 2000~10000mPa·s, 10000~20000mPa·s, 20000~60 000mPa·s, 60000~200000mPa·s, 200000~600000mPa·s or 600000~1800000mPa·s.

[0020] Furthermore, in the step A, the initial polyurethane molecular chain has a chain-breaking group, and in the step A, the molecular chain of the initial polyurethane is broken from the chain-breaking group.

[0021] Further, in step A, the chain-breaking groups include -N(H)n-, -NH-(CO)-O-, -C=C-, A combination of one or more of -O-, -HN-(CO)-NH-, -(CO)-NH-, -NH-(CS)-O-, -C=C-, -S-, -HN-(CS)-NH-, -(CS)-NH-, heterocycle, paracycle, aromatic ring, hexylcycle, macrocycle, polyhedron, isomer or polypeptide.

[0022] Furthermore, after step A is completed, there is a step of removing at least a portion of the degradation products, wherein the removal step comprises a combination of one or more of reduced pressure distillation, separation, filtration, extraction, and fractionation; and the degradation products include at least a portion of the degradation agent and / or solvent that did not participate in the reaction.

[0023] Furthermore, the method further comprises the following steps: Step B: removing and recovering the excess degradation agent in the resin intermediate obtained in Step A.

[0024] Furthermore, in the step B, the removal method includes the reduced pressure distillation.

[0025] Furthermore, in the step C, it further comprises: reacting the resin intermediate with a grafting agent having a grafting group, and subjecting the reaction product to the reduced pressure distillation to prepare a modified polyurethane resin containing initial polymer molecular chain fragments having a chain extension group.

[0026] Furthermore, the temperature of the reduced pressure distillation is 65-95°C, 95-120°C, 120-150°C or 150-200°C; the pressure of the reduced pressure distillation is 0.01-2 mmHg, 2-5 mmHg, 5-20 mmHg, 20-100 mmHg or 100-400 mmHg.

[0027] Furthermore, in the step C, the grafting reaction includes a chemical bonding reaction with a substance containing an active double bond.

[0028] Furthermore, the grafting reaction is an esterification reaction.

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

[0031] The present invention claims to protect the modified polyurethane resin prepared by any one of the above preparation methods.

[0032] The present invention also claims to protect a composite material with any one of the above-mentioned modified polyurethane resins as a matrix.

[0033] Further, the composite material includes a modified polyurethane resin and a reinforcing material, wherein the reinforcing material includes fibers;

[0034] The fibers include one or a combination of fiber fabrics, continuous fiber yarns, short-cut fibers, pelletized fibers, powdered fibers or fillers.

[0035] The present invention further provides a method for preparing the composite material, comprising the following steps: Step e, impregnating fibers with modified polyurethane resin at 0-150° C. to produce the composite material.

[0036] Furthermore, the method further comprises the following steps:

[0037] Step 1: adding a curing agent to the composite material to carry out a curing reaction to obtain a cured resin;

[0038] 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, and 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;

[0039] Free radical initiators include thermosensitive free radical initiators;

[0040] Thermosensitive free radical initiators include peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds or other suitable free radical initiators that can initiate the curing of double bond-containing compounds.

[0041] The present invention further provides a method for preparing the modified polyurethane resin as a semi-cured material for curing the modified polyurethane resin, comprising the following steps:

[0042] Step 2: Add a curing agent to the modified polyurethane resin and mix them to obtain a semi-cured material.

[0043] Further, 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, and 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;

[0044] Free radical initiators include thermosensitive free radical initiators;

[0045] Thermosensitive free radical initiators include peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds or other suitable free radical initiators that can initiate the curing of double bond-containing compounds.

[0046] Furthermore, the semi-cured material is obtained by a free radical polymerization reaction of the modified polyurethane in the presence of the free radical initiator;

[0047] 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;

[0048] The curing agent also includes an accelerator compatible with the free radical initiator;

[0049] The accelerator includes metal salts, organic amines, including cobalt salts, copper salts, zinc salts or aniline accelerators.

[0050] Furthermore, in step 2, a step of heating the modified polymer is included, wherein the modified polymer is heated to 50°C to 180°C.

[0051] The present invention claims protection for a semi-cured material prepared by any one of the above-mentioned preparation methods.

[0052] The present invention further provides a composite material using the above-mentioned semi-cured material as a matrix.

[0053] Furthermore, the composite material includes a semi-cured material and a reinforcing material, and the reinforcing material includes fibers and / or fillers;

[0054] The fiber form includes one or a combination of fiber fabric, continuous fiber yarn, short-cut fiber, ball fiber, and powder fiber;

[0055] The composite material is prepared under reaction conditions where free radical polymerization occurs, and together with the reinforcing material forms a composite material based on the prepreg.

[0056] The present invention also provides an application of the composite material in composite material prepreg, sheet molding compound SMC or bulk molding compound BMC.

[0057] The present invention claims a method for preparing the composite material according to the above, comprising the following steps:

[0058] Step g: heating the semi-cured material to 50-160° C. to impregnate the fibers and / or fillers to produce the composite material.

[0059] Furthermore, the composite material includes a semi-cured material and a reinforcing material, and the reinforcing material includes fibers;

[0060] The fiber form includes one or a combination of fiber fabric, continuous fiber yarn, short-cut fiber, ball fiber, powder fiber, and filler;

[0061] The composite material is prepared under reaction conditions where free radical polymerization occurs, and together with the reinforcing material, forms a composite material based on the semi-cured material;

[0062] The process of impregnating fibers and / or fillers includes: high-speed stirring, centrifugal stirring, screw mixing, rubber roller kneading, stirring and kneading, forming a rubber film composite roll pressing, diluting and then impregnating, composite and then rolling, etc. One or more combinations of the methods. ;

[0063] The composite material is prepared by one or more combinations of pultrusion, prepreg, SMC / BMC, winding, resin transfer, vacuum introduction, hand lay-up, compression, and injection molding.

[0064] In a first aspect, the present invention provides a method for producing a modified polyurethane, wherein the modified polyurethane is obtained by treating an initial polyurethane (the initial polyurethane is a solidified polyurethane that needs to be recycled for reuse), the treatment comprising the following steps:

[0065] Step A: the initial polyurethane reacts with a degradation agent containing an active group to break at least a portion of the molecular chain of the initial polyurethane to form a resin intermediate containing initial polyurethane molecular chain fragments with active groups;

[0066] Step C: reacting the resin intermediate with a grafting agent having a grafting group to prepare a modified polyurethane resin containing an initial polyurethane 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;

[0067] Step I: Then the modified polyurethane is cured, and the initial polyurethane molecular chain fragments in the resin intermediate 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, so as to prepare a cured modified polyurethane resin material.

[0068] In the second aspect, the present invention also provides another method for manufacturing a composite material based on a modified polyurethane resin material, wherein the modified polyurethane resin material is obtained by grafting a resin intermediate obtained by treating an initial polyurethane, and the resin intermediate is obtained by reacting a polyurethane solid with a degradation agent containing an active group, and the specific reaction process is to break at least a portion of the molecular chain of the initial polyurethane, thereby forming a resin intermediate containing an initial polyurethane molecular chain fragment with an active group. The source of the polyurethane solid is mainly polyurethane solid waste:

[0069] According to the method for producing modified polyurethane and composite materials of the first aspect or the second aspect, the resin intermediate for preparing the modified polyurethane resin material is preferably obtained by alcoholysis reaction of the initial polyurethane solid.

[0070] According to the method for manufacturing modified polyurethane and composite materials of the first aspect or the second aspect, the modified polyurethane resin material is obtained by grafting acrylic acid and / or methacrylic acid ester groups onto a resin intermediate through an esterification reaction.

[0071] According to the method for manufacturing modified polyurethane and composite materials of the first aspect or the second aspect, the cured modified polyurethane resin material is obtained by adding a free radical initiator to cause free radical polymerization of the modified polyurethane resin.

[0072] According to the method for manufacturing modified polyurethane and composite materials in the aforementioned second aspect, optionally, a composite material can be prepared by adding fillers or other additives to the modified polyurethane resin and / or impregnating the modified polyurethane resin into fibers, thereby preparing a composite material and further preparing a composite material with the modified polyurethane as the matrix; the filler includes a solid or liquid additive that does not chemically react with the initial polyurethane.

[0073] The thermosetting polyurethane resin composite material can be prepared by various composite material preparation processes, including but not limited to pultrusion process, prepreg process, SMC / BMC process, winding process, resin transfer process, vacuum introduction process, hand lay-up process, compression molding process, injection molding process, etc. or a combination thereof.

[0074] Optionally, the initial polyurethane contains fillers or fibers, and in steps A to E, at least a portion of the fillers or fibers in the initial polyurethane are retained to obtain a composite semi-cured material. Further, through the curing step in step E, a modified polyurethane containing fillers and / or reinforcing materials that meets the target application requirements is obtained, that is, a composite material with the modified polyurethane as a matrix.

[0075] Through this method, the purification step of the initial polyurethane can be eliminated, thus reducing costs and avoiding the pollution of 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 polyurethane containing fillers and / or reinforcement materials that meets the target application requirements, that is, a composite material with a modified polyurethane resin as a matrix.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] In another aspect, the present invention claims a modified polymer prepared by any one of the above methods.

[0085] 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.

[0086] 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:

[0087] 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.

[0088] 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.

[0089] 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 has 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-, -(CO)-, -(CO)-O-, -O-, -HN-(CO)-NH-, -(CO)-NH-, -NH-(CS)-O-, -C=C-, -S-, -HN-CS-NH-, -CS-NH-, a heterocyclic ring, a cyclic ring, an aromatic ring, a hexyl ring, a macrocyclic ring, a polyhedron, an isomer or a polypeptide, or a combination thereof. Preferably, the initial polymer molecule chain carries 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 a combination of one or more of thermal decomposition, hydrolysis, alcoholysis, aminolysis, acidolysis, alkaline hydrolysis, alcohol-alkali reaction, hydrogenolysis or acidolysis.

[0090] Preferably, the degradation reaction comprises the following reactions:

[0091] R1-A-(R2S)+R3-B-→R1-(A1)-R3-B1-+(R2S)-B2-

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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;

[0098] 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:

[0099] Alcoholysis: PU+HO—R—OH to obtain a polyol mixture

[0100] Hydrolysis method: PU + water to obtain polyol + polyamine

[0101] Alkaline hydrolysis: PU + NaOH to obtain amine + alcohol + Na2CO3

[0102] Ammonolysis: PU + NH3 to obtain polyol + amine + urea

[0103] Pyrolysis: PU + high temperature to obtain a mixture of gaseous and liquid fractions

[0104] Hydrocracking method: PU+H2 high temperature and high pressure to obtain a mixture of oil and gas

[0105] 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 c The 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 formula is as follows:

[0106]

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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:

[0111] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0112] 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.

[0113] 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:

[0114] Side reactions of urea groups:

[0115] -R1-NH-CO-NH-R1-+HO-R3-OH→-R1NHCOOR3OH+-R1NH2 At the same time, there are side reactions such as thermal degradation of carbamate and urea groups:

[0116] -R1-NH-CO-O-R2-→-RNCO+HOR2

[0117] -R1-NH-CO-O-(CH2)2-R2-→-R1NH2+CO2+CH2=CHR2

[0118] -R1-NH-CO-OO-R2-→-R1NHR2-+CO2

[0119] -R1-NH-CO-NH-R4-→-R1-NCO+R4NH2

[0120] The above side reactions will eventually generate compounds with hydroxyl or amine groups.

[0121] 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.

[0122] 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:

[0123]

[0124] 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.

[0125] 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.

[0126] 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, 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.

[0127] 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.

[0128] 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.

[0129] 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.

[0130] 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.

[0131] 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 polyurethane products, coatings, 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.

[0132] 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.

[0133] 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.

[0134] 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.

[0135] Preferably, the yield of the alcoholysis reaction is 50-60%, 60-70%, 70-80%, 80-95% or 95-100%.

[0136] Furthermore, in step A, the degradation reaction includes an alcohol reaction or an alkaline hydrolysis reaction. It includes the following reactions:

[0137]

[0138] 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.

[0139] 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:

[0140] R1-NH-CO-O-R2+H2O→-R1NH2+R2OH+CO2, wherein the steam cracking temperature during the degradation reaction is 200-410°C, preferably 220-380°C.

[0141] 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.

[0142] 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.

[0143] 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, 200-1000 mg / g.

[0144] 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.

[0145] 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.

[0146] On the other hand, the present invention claims a modified polymer as a resin intermediate prepared by any one of the above methods.

[0147] 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:

[0148] 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.

[0149] 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:

[0150] R1-A-(R2S)+(R3C)-B-→R1-(A1C)-R3-B1-+(CR2S)-B2-

[0151] 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.

[0152] 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:

[0153] 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.

[0154] 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.

[0155] Further, the production of the modified polymer includes the following reactions:

[0156] R1-A-(R2S)+(R3)-B-→R1-(A1)-R3-B1-+(R2S)-B2-+(R4D)-C-→R1-(A1)-R3-(B1DR4)-C-+(R2S)-(B2DR4)-C-

[0157] 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.

[0158] (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.

[0159] 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.

[0160] 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.

[0161] Preferably, the esterification reaction comprises direct esterification of an acid with an alcohol or phenol, comprising the following reaction:

[0162]

[0163] 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.

[0164] 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:

[0165]

[0166] R′OH+R″COCl→R″COOR′+HCl

[0167] R′X+R″COOM→R″COOR′+MX

[0168] 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:

[0169]

[0170] 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:

[0171] ROH+CH2=CO→CH3COOR

[0172] R′OH+RCN+H2O→RCOOR′+NH3

[0173] R′OH+RCONH2→RCOOR′+NH3

[0174] CH3OCH3+CO→CH3COOCH3

[0175] 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.

[0176] 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.

[0177] Further, in step C, the grafting group includes one or more combinations of amide groups, amine groups, urea groups, hydroxyl groups, carboxyl 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.

[0178] 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;

[0179] 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:

[0180]

[0181] 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.

[0182] 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.

[0183] 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:

[0184]

[0185] RC + O+R1OH→RCOOR1+H +

[0186]

[0187] 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:

[0188] R′OH+R″COCl→R″COOR′+HCl

[0189] Preferably, hexamethylphosphoric acid triamide is used as a solvent or magnesium chips in the esterification reaction of step A;

[0190] 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.

[0191] 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.

[0192] 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.

[0193] 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:

[0194]

[0195] Further, in step C, the grafting agent is D d NE e ; The grafting reaction includes the following reactions:

[0196]

[0197] 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, e functional combinations are similar and fall within the protection scope of the present invention.

[0198] 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:

[0199] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH

[0200] 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:

[0201] -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

[0202] or

[0203] -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-

[0204] 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.

[0205] 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:

[0206] -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

[0207] or

[0208] -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

[0209] 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;

[0210] 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:

[0211] -R-NH-R'+R4-(C=C) a -(CR5) b -(COOH)m→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0212] or

[0213] -R-NH-R'+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0214] 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.

[0215] On the other hand, the present invention claims a modified polymer prepared by any of the above-mentioned methods through grafting reaction treatment.

[0216] 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:

[0217] F: Add a curing agent to the modified polymer and mix them to obtain a semi-cured material.

[0218] 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.

[0219] 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;

[0220] 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.

[0221] Preferably, in step C, the chain extending group comprises an unsaturated double bond.

[0222] 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.

[0223] 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.

[0224] 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.

[0225] Furthermore, the method further comprises the step of:

[0226] 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.

[0227] 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.

[0228] 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.

[0229] On the other hand, the present invention claims a modified polymer prepared as a semi-cured material by any one of the above mixing methods.

[0230] 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:

[0231] 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.

[0232] F: Add a curing agent to the composite material to carry out a curing reaction to obtain a cured resin.

[0233] 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.

[0234] 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.

[0235] 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.

[0236] 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.

[0237] 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;

[0238] 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.

[0239] 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.

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

[0241] 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.

[0242] Further, the process of curing reaction is as follows:

[0243]

[0244] 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.

[0245] As another embodiment, the process of the curing reaction is as follows:

[0246]

[0247] 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.

[0248] Further, in step A, the following reaction is included:

[0249] -R1NHCOOR2-+R3(OH)n→-R1NHCOOR3(OH) (n-1) -+-R2OH Further, in step C, comprises the following reaction:

[0250] -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

[0251] or

[0252] -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-

[0253] In step 1, the free radical initiator generates active free radicals to open the unsaturated double bonds to form free radicals to initiate the crosslinking and curing reaction between the unsaturated double bonds.

[0254] Specifically, the following reactions are included:

[0255]

[0256] 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.

[0257] 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:

[0258] -R-NH-R'+R4-(C=C) a -(CR5) b -(COOH)m→R-NR'-(CO)-(CR5) b -(C=C) a -R4 or

[0259] -R-NH-R'+-R4-(C=C) a -(CR5) b -(CO)O(CO)-→R-NR'-(CO)-(CR5) b -(C=C) a -R4

[0260] 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.

[0261] Specifically, the following reactions are included:

[0262]

[0263] 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.

[0264] On the other hand, the present invention claims a modified polymer prepared by any of the above methods through a curing reaction treatment.

[0265] According to any one of the above methods for preparing a modified polymer, the present invention also provides the following preferred embodiments.

[0266] 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.

[0267] 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.

[0268] 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.

[0269] As a preferred embodiment, step A further comprises the following steps:

[0270] 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.

[0271] As a preferred embodiment, the step C further includes the following steps:

[0272] 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.

[0273] 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.

[0274] 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.

[0275] 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.

[0276] 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.

[0277] 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.

[0278] 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.

[0279] 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.

[0280] As a preferred embodiment, the free radical initiator includes but is not limited to a peroxide initiator and a promoter thereof.

[0281] As a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, and the cured polyurethanes comprise polyurethane waste.

[0282] As another preferred embodiment, the resin intermediate is compounded from different polymer resin intermediates made from different initial polymers.

[0283] 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.

[0284] As a preferred embodiment, the number average molecular weight of the resin intermediate measured by RID and VWD (254nm) 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.

[0285] 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.

[0286] 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.

[0287] As a preferred embodiment, the amine value of the modified resin is 0-20, 20-40, 40-80 or 80-150 mgKOH / g.

[0288] 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

[0289] 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.

[0290] 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 one or more selected from amide, urea, hydroxyl, carboxyl, anhydride or epoxy. 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.

[0291] 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 group and / or amine group on the resin intermediate.

[0292] 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.

[0293] 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.

[0294] 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.

[0295] 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.

[0296] 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.

[0297] 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.

[0298] 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.

[0299] 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.

[0300] As a preferred embodiment, the initial polymer comprises one or more cured polyurethanes, and the cured polyurethanes comprise polyurethane waste.

[0301] 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.

[0302] 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.

[0303] 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.

[0304] 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%.

[0305] 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.

[0306] 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.

[0307] In another aspect, the present invention claims a modified polymer resin prepared by any one of the above methods.

[0308] The invention discloses a modified polyurethane and a manufacturing method thereof, wherein a part of the initial polyurethane molecular chain is opened to become a resin intermediate containing an initial polyurethane molecular fragment with an active group or a resin intermediate containing an initial polyurethane molecular fragment with a chain extension group, and then the resin intermediate is converted into a liquid modified polyurethane resin containing an initial polyurethane molecular fragment with an active double bond group through a grafting reaction, and then the modified polyurethane resin is cured to become a plate curing material, or the modified polyurethane is mixed with reinforcing materials such as fillers or fibers, and then cured to obtain a composite material based on a thermosetting modified polyurethane resin. In this process, the molecular weight and molecular structure of the initial polyurethane are adjusted by designing and controlling the chemical reaction, and the additives are designed and controlled to obtain a modified polyurethane with target performance, a semi-cured material as a thermosetting modified polyurethane resin, and a composite material based on the resin.

[0309] The present invention has found that only a portion of the energy of the existing polyurethane degradation method is needed to open a portion of the polyurethane molecular chain to convert it into a polymer resin intermediate, and then the resin intermediate is finally subjected to a grafting reaction to become a liquid modified polyurethane resin. In this process, the molecular weight and molecular structure of the initial polyurethane are adjusted to meet the requirements of the use environment for the performance of the polyurethane.

[0310] The invention provides a modified polyurethane, a semi-cured material, a composite material and a preparation method thereof. By designing and adjusting the chemical reactions in each manufacturing step, the cured initial polyurethane is reacted with a degradation agent to prepare a resin intermediate with an active terminal group. By introducing reactants and cross-linking groups, specifically unsaturated carboxylic acids or unsaturated carboxylic anhydrides as grafting agents, and reacting with the active terminal groups, a modified polyurethane with a chain extension or cross-linking reaction group, i.e., an unsaturated double bond, is prepared. By adding a free radical initiator to initiate the mutual reaction of unsaturated double bonds in the modified polyurethane, a molecular chain extension and cross-linking curing reaction are performed to obtain a cured polyurethane resin as a semi-cured material. 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 prevent the resin from foaming and gelling prematurely is avoided, so that the resin has a longer process operation time, so that the modified polyurethane as a processing raw material of a composite material can adapt to the traditional composite material processing technology, while the existing polyurethane resin needs complex equipment assistance to manufacture the composite material; and the invention can also optimize the initial polyurethane molecular structure, so that the comprehensive mechanical properties of the cured polyurethane resin can be significantly improved. DETAILED DESCRIPTION

[0311] The detailed features and advantages of this patent are described in detail in the specific implementation method below, and the content is sufficient to enable any technical personnel in this field to understand the technical content of this patent and implement it accordingly. According to the description and claims disclosed in this specification, the technical personnel in this field can easily understand the relevant purposes and advantages of this patent.

[0312] In order to make the purpose, technical solutions and advantages of this patent clearer, the implementation method of this patent will be further described in detail below.

[0313] The raw materials used in this embodiment can be purchased on the market. Diphenylmethane diisocyanate (PMDI): trade name 44V20L, purchased from Covestro; polyols are NJ-303 and NJ-204, purchased from Jurong Ningwu New Materials Company; dibenzoyl peroxide: purchased from Nouryon; diisopropylbenzene peroxide, brand: PdBC-ff, purchased from Nouryon; butanediol (BDO), methacrylic acid (MAA), purchased from Sinopharm Group; gingham, brand: EWR400, purchased from Chongqing International Composite Materials Co., Ltd.; methyl ethyl ketone peroxide (MEKP), blue water (cobalt isooctanoate), ethylene glycol diacrylate: purchased from Sinopharm Group; release agent, brand Loctite 55-NC, Henkel, Germany.

[0314] Comparative Example 1

[0315] Mix 100g of NJ-303 and 113g of PMDI at 25℃ and 60% relative humidity, stir for 30 seconds, pour into a mold preheated to 70℃ in an oven, raise the oven temperature to 120℃ within 20 minutes and keep it for 30 minutes, then turn off the oven to stop heating and let the polyurethane resin formed on the mold cool naturally to room temperature. Take out the mold to obtain a cured polyurethane resin plate.

[0316] Comparative Example 2

[0317] Mix 60g of NJ-303, 40g of NJ-204 and 95g of PMDI at 25℃ and 60% relative humidity, stir for 30 seconds, pour into a mold preheated to 70℃ in an oven, raise the oven temperature to 120℃ within 20 minutes and keep it for 30 minutes, then turn off the oven to stop heating and let the polyurethane resin formed on the mold cool naturally to room temperature. Take out the mold to obtain a cured polyurethane resin plate.

[0318] Comparative Example 3

[0319] 90 g of NJ-303, 10 g of BDO and 95 g of PMDI were mixed under the environmental conditions of 25°C and 60% relative humidity, stirred for 30 seconds, and poured into a mold preheated to 70°C in an oven. The oven temperature was then raised to 120°C within 20 minutes and maintained for 30 minutes. The oven was then turned off to stop heating, and the polyurethane resin formed on the mold was allowed to naturally cool to room temperature. The mold was taken out to obtain a solidified polyurethane resin plate.

[0320] The polyurethane resin plates obtained in Comparative Examples 1-3 were observed for their appearance, and samples were cut to test their bending mechanical properties according to GB / T 2567-2008 Test Method for Properties of Resin Castings.

[0321] Gel time: Mix all raw material components, stir for 30 seconds, and test the gel time according to the test standard "GB / T 7193-2008".

[0322] Table 1: Polyurethane resin reactivity, cured sheet quality and mechanical properties

[0323]

[0324] As can be seen from Table 1, due to the sensitivity to water, the polyurethane resin plates prepared in Comparative Examples 1 to 3 all contain bubbles, resulting in poor comprehensive mechanical properties: the gel time of Comparative Examples 1 to 2 is not long, and the mechanical properties are not good enough; although the mechanical properties of Comparative Example 3 have been improved to a certain extent, the gel time is greatly shortened, and the elongation at break has not been significantly improved. This is because the isocyanate group contained in PMDI easily reacts with water to generate carbon dioxide and urea, resulting in bubbles in the generated polyurethane and reduced performance; at the same time, the isocyanate group is highly active and reacts quickly, which will cause the polyurethane resin to quickly gel and lose its process operation function.

[0325] In addition, the PMDI directly used in Comparative Examples 1 to 3 contains an isocyanate component (black material component) at the end group as a curing agent to generate carbamate with a reaction precursor containing a hydroxyl group to cure the polyurethane resin to obtain an initial polyurethane, that is, to generate a polyurethane containing a carbamate group, which cannot avoid the potential risk of isocyanate toxicity. Due to the high toxicity of the isocyanate group, direct operation of compounds containing isocyanate end groups poses a risk to human health. In particular, the manufacture of isocyanates requires a highly toxic reaction precursor such as phosgene, so the production process requires very strict control, resulting in high production costs. Therefore, the production of polyurethane in Comparative Examples 1 to 3 must adopt strict process control means and complex equipment to avoid the above problems, resulting in high costs.

[0326] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a novel polyurethane resin which is modified from the existing polyurethane resin to obtain a better performance and structure.

[0327] Example 1

[0328] The solidified polyurethane resin of comparative example 1 is used as the initial polyurethane for modification. The initial polyurethane is crushed by a crusher, 100 grams of powder is taken, poured into a round-bottom flask, and 500 grams of 1,2-propylene glycol is added and mixed; the mixture is heated and refluxed for 16 hours under mechanical stirring, and then cooled to room temperature, filtered, and the filtrate is then distilled under reduced pressure to remove excess 1,2-propylene glycol to obtain a liquid polyurethane resin intermediate, and the fraction collected by distillation can be reused; the liquid polyurethane resin intermediate and 100 grams of methyl acrylate are mixed and the mixture is stirred for 16 hours. Add enoyl chloride, 300 ml of dichloromethane and 50 g of triethylamine into a round-bottom flask, add 0.2 g of hydroquinone, stir at 0 ° C for 3 hours, then naturally heat to 25 ° C and continue stirring for 12 hours, then filter, remove the liquid by rotary evaporation, and then redissolve in 300 ml of dichloromethane, wash 3 times with 80 ml of 10% sodium carbonate aqueous solution and saturated brine respectively, dry the organic layer with anhydrous sodium sulfate for 3 hours, filter again, and evaporate the solvent from the filtrate to obtain a liquid modified polyurethane.

[0329] Example 2

[0330] The solidified polyurethane resin in Comparative Example 2 is used as the initial polyurethane for modification. The initial polyurethane is crushed by a crusher, 100 grams of powder is taken, poured into a round-bottom flask, and 500 grams of ethylene glycol is added and mixed; the mixture is heated to reflux for 16 hours under mechanical stirring, then cooled to room temperature, filtered, and the filtrate is distilled under reduced pressure until the hydroxyl value is 400 to obtain a liquid polyurethane resin intermediate, and the fraction collected by distillation can be reused; the liquid polyurethane resin intermediate and 300 grams of acrylic acid are added to a round-bottom flask, 0.2 grams of hydroquinone is added, and the mixture is stirred at 140° C. for less than 2 hours. If the modified polyurethane is stirred for more than 2 hours, cross-linking will occur, and nitrogen is bubbled continuously to blow out the generated water vapor from the condenser at the upper end of the flask, and the mixture is cooled to 90° C. and distilled under reduced pressure to obtain a liquid modified polyurethane, and the fraction collected by distillation can be reused.

[0331] Embodiment 3:

[0332] The hard foam in the shell of the discarded Haier refrigerator contains polyurethane, which is used as the initial polyurethane material for modification. The initial polyurethane is crushed with a crusher, and 100 grams of powder is taken after crushing, poured into a round-bottom flask, and then 350 grams of diethylene glycol are added; under mechanical stirring, heated and refluxed for 12 hours, then cooled to room temperature, filtered, and the filtrate is then decompressed and distilled to remove excess diethylene glycol to obtain a liquid polyurethane resin intermediate, and the distillation collected fraction can be reused. The liquid polyurethane resin intermediate and 300 grams of methacrylic acid are added to a round-bottom flask, and 0.2 grams of phenothiazine are added, stirred at 140°C for 3 hours, and nitrogen is bubbled all the time, the generated water vapor is blown out from the condenser at the upper end of the flask, and then cooled to 90°C, and decompressed and distilled to obtain a modified polyurethane, and the distillation collected fraction can be reused.

[0333] Embodiment 4:

[0334] The hard foam in the shell of the discarded Haier refrigerator contains polyurethane, which is used as the initial polyurethane material for modification. The initial polyurethane is crushed with a crusher, and 100 grams of powder is taken after crushing, poured into a round-bottom flask, and then 350 grams of diethylene glycol are added; under mechanical stirring, heated and refluxed for 12 hours, then cooled to room temperature, filtered, and the filtrate is then decompressed and distilled to remove excess diethylene glycol to obtain a liquid polyurethane resin intermediate, and the distillation collected fraction can be reused. Take out 100 grams of the liquid polyurethane resin intermediate, mix it with 30 grams of NJ-204 and 300 grams of methacrylic acid and add it to a round-bottom flask, add 0.2 grams of hydroquinone, stir at 140°C for 3 hours, and keep bubbling nitrogen to blow out the generated water vapor from the condenser at the upper end of the flask, and then cool to 90°C, and decompress and distill to obtain a modified polyurethane, and the distillation collected fraction can be reused.

[0335] Embodiment 5:

[0336] The hard foam in the discarded Haier refrigerator shell and the soft foam under the discarded Iris sofa cushion both contain polyurethane, which are crushed separately, and 75 grams of powder of the hard foam and 25 grams of powder of the soft foam are taken, mixed to form the initial polyurethane material for modification, and the initial polyurethane is poured into a round-bottom flask, and 350 grams of 1,6-hexanediol are added; under mechanical stirring, heated and refluxed for 8 hours, then cooled to room temperature, filtered, and the filtrate is then vacuum distilled to remove excess small molecule alcohol, i.e., 1,6-hexanediol, to obtain a liquid polyurethane resin intermediate. The liquid polyurethane resin intermediate and 300 grams of methacrylic acid are added to a round-bottom flask, and 0.2 grams of hydroquinone are added, stirred at 140°C for 3 hours, and nitrogen is bubbled all the time to blow the generated water vapor out from the condenser at the upper end of the flask, and then cooled to 90°C, and vacuum distilled to obtain a modified polyurethane, and the fraction collected by distillation can be reused.

[0337] Comparative Example 4:

[0338] Add 140g of NJ-303 and 400g of methacrylic acid into a round-bottom flask, add 0.2g of hydroquinone, stir at 140℃ for 3 hours, and keep bubbling nitrogen to blow out the generated water vapor from the condenser at the top of the flask. Then cool to 90℃ and distill under reduced pressure to obtain liquid polyacrylate resin; the fraction collected by distillation can be reused.

[0339] Take the modified polyurethane obtained in the above examples 1 to 5 and the polyacrylate resin of comparative example 4, add a certain amount of hydroxyethyl methacrylate, and then add 2% of the weight of the modified polyurethane as a free radical initiator dibenzoyl peroxide (PdL), stir and dissolve into a uniform solution, a part of it is used to test the gel time, and the other part is poured into a mold preheated to 70°C in advance, and then heated to 120°C within 20 minutes and maintained for 30 minutes to obtain a cured polyurethane resin plate (i.e., semi-cured material), and test its mechanical properties according to "GB / T 2567-2008 Test Method for Properties of Resin Castings". The test results are shown in Table 2 below:

[0340] Table 2: Resin reactivity, cured sheet quality and mechanical properties obtained in Examples 1 to 5 and Comparative Example 4

[0341]

[0342] It can be seen from the test data in Table 2 that the polyurethane resin obtained by the present invention has no risk of isocyanate exposure during the operation process; the resin also does not have moisture sensitivity and foaming problems, so the obtained polyurethane resin board avoids the potential quality risks caused by foaming, and the gel time is significantly longer than that of ordinary polyurethane resin, and has very good composite material processing and operation processability. And after the modified polyurethane is cured, the mechanical properties are also significantly better than those of ordinary polyurethane resin, and compared with comparative example 4 without polyurethane, the performance of the modified polyurethane is also improved, especially the elongation at break is improved, indicating that the toughness is improved and the advantages of polyurethane are brought into play.

[0343] The difference between Example 2 and Example 1 is that the components of the polyol used to manufacture the initial polyurethane are different and the degradation agents used are different. Example 2 uses a 2-functionality long-chain low-hydroxyl polyol NJ-204 to replace a portion of a 3-functionality short-chain high-hydroxyl polyol NJ-303, thereby improving the toughness of the manufactured polyurethane resin.

[0344] In Example 2, a portion of the trifunctional short-chain high-hydroxyl polyol NJ-303 was replaced with a difunctional long-chain low-hydroxyl polyol NJ-204 to modify the molecular chain of the initial polyurethane of Example 1, thereby improving the flexibility of the molecular chain and improving the toughness of the manufactured polyurethane resin. This proves that as long as the properties of the initial polyurethane molecules are improved, the performance of the manufactured polyurethane resin can be improved by the method of the present invention.

[0345] The difference between Example 3 and Examples 1 and 2 is that the raw material sources of the initial polyurethane are different and the degradation agent is different. The initial polyurethane of Example 3 is modified by replacing the new polyurethane made by the prior art with common polyurethane waste. The results show that the polyurethane resin made from the waste prepared by the method of the present invention and the new polyurethane have similar properties, and are both better than the polyurethane made by isocyanate in the prior art, and also better than the performance of the acrylic polyurethane made by the comparative example 4 without polyurethane and completely using the degradation agent and unsaturated acid.

[0346] Since the molecular structure and the content of carbamate characteristic groups in the polyurethane waste are similar to those of the polyurethane made from new materials, if there is no carbamate group, only ester group and acrylate group, it will not have the characteristics of containing carbamate groups, such as toughness. In Example 3, because diethylene glycol with higher flexibility and all terminal groups are primary hydroxyl groups is used to replace ethylene glycol, the flexibility of the molecular chain of the initial polyurethane is improved, and the toughness of the polyurethane resin is improved.

[0347] The difference between Example 4 and the previous Example 3 is that polyol NJ-204 is added to the resin intermediate, that is, unsaturated acid, for esterification to obtain a polyurethane resin with higher toughness. Since the initial polyurethane is a hard foam, the resin intermediate obtained after degradation has a short molecular chain and a high degree of branching, so the toughness of the polyurethane resin prepared in Example 3 is still insufficient. After adding the long-chain 2-functional polyol NJ-204, the polyurethane resin produced in Example 4 has flexible polyester molecules with unsaturated double bonds. The soft segment of the flexible polyester molecule is connected to the hard segment of the hard polyurethane molecule through the reaction of the unsaturated double bonds, which improves the initial polyurethane molecular structure and makes the polyurethane resin have better toughness.

[0348] The difference between Example 5 and Example 3 is that a part of the polyurethane rigid foam waste is replaced by polyurethane soft foam waste as the initial polyurethane, and long-chain 1,6-hexanediol is used instead of diethylene glycol, and a polyurethane resin with higher toughness is obtained.

[0349] Since the polyurethane soft foam waste is made of isocyanate and long-chain polyol, long-chain polyol is generated in the resin intermediate after degradation, which is equivalent to introducing long-chain polyol into the resin intermediate. According to the principle similar to Example 4, the toughness of the polyurethane resin can be improved. In addition, 1,6-hexanediol does not contain ether bonds, and the degradation agent is not easily oxidized and decomposed during high-temperature degradation, which is beneficial to reducing by-products during the degradation process and the degradation agent being repeatedly reused after being collected by vacuum distillation.

[0350] Example 6

[0351] The hard foam in the discarded Haier refrigerator shell and the soft foam under the discarded Iris sofa cushion both contain polyurethane. They are crushed separately, and 75 grams of powder of the hard foam and 25 grams of powder of the soft foam are taken, mixed to form the initial polyurethane material for modification. The initial polyurethane is poured into a round-bottom flask, and then 350 grams of 1,6-hexanediol are added; under mechanical stirring, heated and refluxed for 8 hours, then cooled to room temperature, filtered, and a liquid polyurethane resin intermediate is obtained. The hydroxyl value of the liquid polyurethane resin intermediate is tested, and then 0.95 moles of methacrylic acid are added according to the molar number of hydroxyl groups, and 0.075% of hydroquinone by weight of methacrylic acid is added, stirred at 140°C for 3 hours, and nitrogen is bubbled all the time to blow the generated water vapor out from the condenser at the upper end of the flask, and then cooled to 90°C and vacuum distilled to obtain modified polyurethane.

[0352] Example 7

[0353] The hard foam in the discarded Haier refrigerator shell and the soft foam under the discarded Iris sofa cushion both contain polyurethane, which are crushed separately, and 75 grams of powder of the hard foam and 25 grams of powder of the soft foam are taken, mixed to form the initial polyurethane material for modification, and the initial polyurethane is poured into a round-bottom flask, and then 350 grams of 1,6-hexanediol are added; under mechanical stirring, heated and refluxed for 8 hours, then cooled to room temperature, filtered, and a liquid polyurethane resin intermediate is obtained. The hydroxyl value of the liquid polyurethane resin intermediate is tested, and then 0.95 moles of methacrylic acid are added according to the molar number of hydroxyl groups, and 0.075% of hydroquinone by weight of methacrylic acid is added, stirred at 140°C for 3 hours, and nitrogen is bubbled all the time, and the generated water vapor is blown out from the condenser at the upper end of the flask, and then cooled to 90°C to obtain a modified polyurethane.

[0354] Mix the components according to the proportions in Table 3, stir and dissolve into a uniform solution, use a portion to test the gel time, and pour the other portion into a mold preheated to 70°C, then heat to 120°C within 20 minutes and keep for 30 minutes to obtain a cured modified polyurethane plate (i.e., semi-cured material), and test its mechanical properties (TBPB) according to GB / T 2567-2008 Test Method for Properties of Resin Castings. The test results are shown in Table 3 below:

[0355] Table 3: Resin reactivity, cured sheet quality and mechanical properties obtained in Examples 6 to 7

[0356]

[0357]

[0358] Example 6 eliminates the reduced pressure distillation step after the degradation reaction is completed, and obtains a high-viscosity polyurethane resin intermediate with a high carbamate content and a reactive diluent.

[0359] Embodiment 7 eliminates the vacuum distillation step after the degradation reaction and the vacuum distillation step after the esterification reaction, simplifies the reaction, and obtains a low-viscosity modified polyurethane resin, and the performance of this modified polyurethane resin does not decrease. This is because the vacuum distillation step is removed, so that the degradation agent participates in the esterification reaction as a part of the resin intermediate, and the short-chain degradation agent reacts with the unsaturated acid ester to generate a short-chain acrylate with low viscosity, which becomes the active diluent of the polyurethane resin intermediate and participates in the curing reaction, becoming a part of the cured polyurethane resin. In this way, this embodiment completes the preparation of the active diluent and the preparation of the modified polyurethane in one step. The modified polyurethanes obtained in both Embodiment 6 and Embodiment 7 have independent characteristics and uses, respectively, which expands the application field of the product.

[0360] The invention further provides a process for using the polyurethane resin to prepare a composite material.

[0361] Embodiment 8:

[0362] The modified polyurethane obtained in Example 3 was obtained, heated to 90° C. to reduce the viscosity, and then 1% of diisopropylbenzene peroxide by weight of the resin was added and stirred for 20 minutes to promote the dissolution of diisopropylbenzene peroxide in the modified polyurethane to obtain a resin mixture (i.e., semi-cured material).

[0363] Place a polyethylene (PE) film on a hot plate heated to 90°C, and then place a layer of 400 g / m 2 Heavy gingham cloth, pour the above resin mixture on the gingham cloth while it is hot, put another layer of the same gingham cloth, and then put another layer of PE film; use a roller to roll and press the PE film and drive away the air in the gaps of the glass fiber, so that the resin mixture fully impregnates the four layers of gingham cloth. Then transfer the impregnated glass fiber cloth together with the upper and lower layers of PE film to a flat table and cool it to room temperature to obtain a prepreg. After being placed at room temperature for 24 hours, the prepreg is soft and plastic, easy to cut, and slightly sticky but not sticky after the PE film is torn off, which meets the process requirements for prepreg materials.

[0364] Further, the prepreg material is cured, the PE film of the prepreg is torn off, 3 prepregs are stacked together (a total of 6 layers of chequered cloth), and hot pressed on a press. The temperature of the lower layer of the press is 150°C, the temperature of the upper layer is 160°C, and the pressure is 3MPa maintained for 10 minutes. After cooling to less than 50°C, demolding is performed to obtain a cured polyurethane resin composite material plate with a thickness of 1.9mm.

[0365] Embodiment 9:

[0366] The modified polyurethane obtained in Example 5 was obtained, and 20% of the resin weight of ethylene glycol diacrylate, 2% of methyl ethyl ketone peroxide (MEKP) and 0.3% of blue water (cobalt isooctanoate) were added and stirred and mixed evenly to obtain a resin mixture (i.e., semi-cured material).

[0367] The resin mixture is brushed on a layer of 400g checkered cloth. After the resin fully impregnates the glass fiber cloth, another layer of glass fiber cloth is stacked on the glass fiber cloth, and then the resin mixture is brushed on it to fully impregnate the second layer of glass fiber cloth. The operation is carried out sequentially, and a total of 6 layers of glass fiber cloth are stacked to obtain a hand-laid fiber impregnation material. The hand-laid fiber impregnation material is then sandwiched between two layers of flat tempered glass plates with a release agent, with a thickness limit of 1.9mm, and placed for 24 hours to cure at room temperature, and then placed in a 100°C oven for curing for 1 hour, and then cooled to room temperature to obtain a cured polyurethane resin composite material plate. Among them, the release agent can be used based on the type of release agent commonly used in the prior art, and the present invention will not be repeated here.

[0368] Comparative Example 5:

[0369] The polyurethane resin prepared in Comparative Example 1 was obtained, heated to 90° C. to reduce the viscosity, and then 1% of diisopropylbenzene peroxide by weight of the resin was added and stirred for 20 minutes to promote the dissolution of diisopropylbenzene peroxide in the modified polyurethane to obtain a resin mixture.

[0370] Place a polyethylene (PE) film on a hot plate heated to 90°C, and then place a layer of 400 g / m 2 Heavy gingham cloth, pour the above resin mixture on the gingham cloth while it is hot, put another layer of the same gingham cloth, and then put another layer of PE film; use a roller to roll and press the PE film and drive away the air in the gaps of the glass fiber, so that the resin mixture fully impregnates the four layers of gingham cloth. Then transfer the impregnated glass fiber cloth together with the upper and lower two layers of PE film to a flat table and cool it to room temperature to obtain a prepreg. The prepreg was placed at room temperature for 24 hours. It was found that the obtained prepreg had many bubbles and felt very hard, so it had no plasticity and was difficult to cut, so it was not suitable for use as a prepreg, let alone the subsequent curing steps.

[0371] Comparative Example 6:

[0372] The polyurethane resin prepared in Comparative Example 2 was obtained, and 20% of the weight of the resin, 2% of methyl ethyl ketone peroxide (MEKP) and 0.3% of blue water (cobalt isooctanoate) were added and stirred and mixed evenly to obtain a resin mixture.

[0373] The resin mixture was brushed on a layer of 400 g square cloth. After the resin fully impregnated the glass fiber cloth, another layer of glass fiber cloth was stacked on the glass fiber cloth, and then the resin mixture was brushed on it to fully impregnate the second layer of glass fiber cloth. The operation was carried out sequentially, and a total of 6 layers of glass fiber cloth were stacked to obtain a hand-laid fiber impregnation material. The hand-laid fiber impregnation material was then sandwiched between two layers of flat tempered glass plates with a release agent, with a thickness limit of 1.9 mm, and placed for 24 hours to cure at room temperature, and then placed in a 100°C oven for 1 hour, and then cooled to room temperature to obtain a cured composite material board. However, after being placed at room temperature for 24 hours, it can be observed that although the composite material can be cured, there are many bubbles. After curing in a 100°C oven for 1 hour, there are still many bubbles. This shows that ordinary polyurethane is not suitable for preparing qualified composite materials through conventional composite material processes due to its water sensitivity.

[0374] The composite material plate samples of Example 8, Example 9 and Comparative Example 6 were subjected to tensile tests (test standard GB / T1447-2005), and the results are listed in Table 4:

[0375] Table 4: Composite material board properties

[0376] Example 8 Example 9 Comparative Example 6 Appearance No bubbles No bubbles Lots of bubbles Tensile strength(MPa) 390 280 130 Tensile modulus(GPa) 22 17.5 12.6 Elongation at break (%) 2.4 2.6 1.7 Is there a risk of isocyanate exposure? none none have

[0377] Example 8 shows a process for making a composite material of a polyurethane resin with high viscosity and high carbamate content, which is used for the preparation of a semi-cured material. Its characteristic is that heating is required to reduce the viscosity of the polyurethane resin. This method can realize the application of resins with high polyurethane content, on the one hand, it can reduce the cost of polyurethane resin in the modification process, and on the other hand, it can also improve the performance of polyurethane resin. Because the higher the content of the initial polyurethane waste, the higher the carbamate content, the better the performance of the polyurethane resin obtained, and the lower the production cost.

[0378] Example 9 demonstrates a method for adapting the modified polyurethane obtained in Example 5 to the requirements of low-viscosity composite material processes, using low-viscosity ethylene glycol diacrylate as an active diluent to reduce the viscosity of materials with high polyurethane content, so that it can adapt to the requirements of various composite material processes.

[0379] It can be seen from the test data in Tables 1 to 4 above that the polyurethane resin obtained by the present invention does not have moisture sensitivity and foaming problems even if it is not cured under strict closed conditions. Therefore, the obtained resin plate avoids the potential quality risks caused by foaming, and the gel time is significantly longer than that of the existing polyurethane resin, which greatly improves the process convenience of polyurethane resin in composite material processing operations. After the modified polyurethane is cured, the mechanical properties are also significantly better than those of the existing polyurethane resin. Moreover, compared with Comparative Examples 4 and 7 using the prior art, the performance of the polyurethane resin and its composite material of the present invention is also improved, especially the elongation at break is improved, indicating that the toughness is improved and the advantages of polyurethane are brought into play.

[0380] The present invention reduces or even avoids the direct use of the polyurethane black component MDI to directly participate in the reaction to prepare the polyurethane resin material, but further processes the existing already cured polyurethane resin to modify and prepare a polyurethane resin with better performance. The polyurethane resin provided by the present invention can not only maintain the unique advantages of polyurethane itself, but also reduce or even avoid the above-mentioned problems of the prior art, and can also optimize the original polyurethane molecular structure by introducing new reactants and cross-linking groups, so that the resin has a longer process operation time, and the comprehensive mechanical properties of the cured resin can also be significantly improved. The introduced new reactants and cross-linking groups can be acids or acid anhydrides or carboxylates, which react with the hydroxyl groups of the resin intermediates to form ester bonds through esterification, and accordingly, the main chain segments of the reactants are also introduced into the molecular main chain of the initial polyurethane, optimizing the original polyurethane molecular structure. Furthermore, through the active groups on the reactants, such as the unsaturated double bonds on the acid or anhydride or carboxylate compound, the generated new resin has new cross-linking groups, such as unsaturated double bonds. In this way, the modified polyurethane can be cross-linked through the new cross-linking groups. The new cross-linking groups such as unsaturated double bonds are more controllable than isocyanate groups. They may not react at low temperatures or room temperatures, but only react at a certain temperature. The practicality of their use is far better than that of isocyanate groups. Therefore, the working performance of the modified polyurethane can be greatly improved.

[0381] In addition, the present invention uses much lower-cost polyurethane waste for degradation, uses unsaturated carboxylic acid and alcoholysis product for esterification, introduces new cross-linking group unsaturated double bonds, and modifies the polyurethane molecular chain through degradation agents and unsaturated carboxylic acids with different structures, thereby improving its mechanical properties and process operation performance. In addition, the present invention further manufactures composite semi-cured materials and composite materials using the polyurethane resin produced by this method, which greatly improves the existing composite materials.

[0382] It should be noted that there are other options for the steps of using alcoholysis to degrade the initial polyurethane to prepare a resin intermediate, then introducing unsaturated double bond cross-linking groups through esterification to modify the polyurethane resin, and finally using an initiator to cure the resin to prepare polyurethane, such as:

[0383] The new resin is produced by degrading the initial polyurethane using a compound containing both hydroxyl groups and unsaturated groups;

[0384] Degrading the initial polyurethane using other methods to make new resins with cross-linking groups;

[0385] The initial polyurethane is degraded by other methods to produce a resin intermediate with active groups, and then new reactants are introduced through the reaction of the active groups to produce modified polyurethane. Finally, the modified polyurethane is cured by the reaction of the active groups on the new reactants to produce a cured polyurethane resin with better performance.

[0386] The terms and expressions used herein are for descriptive purposes only, and the patent shall 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, changes and substitutions may also exist. Accordingly, the claims should be deemed to cover all such equivalents.

[0387] Similarly, it should be pointed out that although this patent 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 this patent, and various equivalent changes or substitutions can be made without departing from the spirit of this patent. Therefore, as long as the changes and modifications to the above embodiments are within the essential spirit of this patent, they will fall within the scope of the claims of this patent.

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.

2. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: The initial polyurethane comprises pure polyurethane and / or polyurethane composite; The polyurethane composite contains fillers and / or fibers, wherein the fillers include solid or liquid additives that do not chemically react with the initial polyurethane.

3. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: The initial polyurethane comprises at least one polyurethane waste that has lost its use function, or the resin intermediate is prepared by compounding a plurality of resin intermediates made from the initial polyurethane.

4. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: In the step A, the initial polyurethane comprises a thermoplastic polyurethane having a linear or branched molecular structure and / or a thermosetting polyurethane having a cross-linked network molecular structure.

5. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: The degradation reaction includes one or more combinations of pyrolysis, hydrolysis, alcoholysis, esterification, transesterification, aminolysis, acidolysis, alkaline hydrolysis, alcohol-alkali reaction, hydrogenolysis or acylation reaction.

6. The method for preparing a modified polyurethane resin according to claim 5, characterized in that: In the step A, the degradation agent carries the chain extension group having the chain extension or cross-linking function, and the chain extension group can react with other groups or itself to achieve molecular chain extension or cross-linking; The chain extension group includes one or more combinations of amide groups, urea groups, amine groups, hydroxyl groups, carboxyl groups, carboxyl groups, unsaturated double bonds, ester groups, epoxy groups or aldehyde groups.

7. The method for preparing a modified polyurethane resin according to claim 6, characterized in that: The degradation agent contains at least one active group, which includes a combination of 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.

8. The method for preparing a modified polyurethane resin according to claim 7, characterized in that: The degradation agent is an alcoholysis agent, and the degradation agent includes a polyol, and the polyol includes a diol and / or a high-functionality polyol; the alcoholysis reaction temperature 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 0.5-2h, 2-3h, 3-6h, 6-12h, 12-24h, 24-48h or 48-64h; the alcoholysis reaction yield is 50-60%, 60-70%, 70-80%, 80-95% or 95-100%; the resin intermediate has a number average molecular weight measured by two detectors, RID and VWD (254nm), ranging from 150 to 200; 200 to 350; 350 to 700; 700~1000, 700~1000, 1000~1800, 1800~3000, 3000~5000, 5000~10000, 10000~30000 or 30000~60000 g / mol; the viscosity at room temperature (25°C) is 50~200 mPa·s, 200~500 mPa·s, 500~10 00mPa·s, 1000~2000mPa·s, 2000~10000mPa·s, 10000~20000mPa·s, 20000~600 00mPa·s, 60000~200000mPa·s, 200000~600000mPa·s or 600000~1800000mPa·s.

9. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: In the step A, the initial polyurethane molecular chain carries a chain-breaking group, and in the step A, the molecular chain of the initial polyurethane is broken from the chain-breaking group.

10. The method for preparing a modified polyurethane resin according to claim 9, characterized in that: In the step A, the chain-breaking groups include -N(H)n-, -NH-(CO)-O-, -C=C-, - A combination of one or more of -O-, -HN-(CO)-NH-, -(CO)-NH-, -NH-(CS)-O-, -C=C-, -S-, -HN-(CS)-NH-, -(CS)-NH-, heterocycle, paracycle, aromatic ring, hexylcycle, macrocycle, polyhedron, isomer or polypeptide.

11. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: After step A is completed, there is a step of removing at least a portion of the degradation products, wherein the removal step comprises a combination of one or more of reduced pressure distillation, separation, filtration, extraction, and fractionation; and the degradation products include at least a portion of the degradation agent and / or solvent that did not participate in the reaction.

12. The method for preparing a modified polyurethane resin according to claim 11, characterized in that: The following steps are also included: Step B: removing and recovering the excess degradation agent in the resin intermediate obtained in step A.

13. The method for preparing a modified polyurethane resin according to claim 12, characterized in that: In the step B, the removal method includes the reduced pressure distillation.

14. The method for preparing a modified polyurethane resin according to claim 11, characterized in that: In the step C, further comprising: The resin intermediate is reacted with a grafting agent having a grafting group, and the reaction product is subjected to the reduced pressure distillation to prepare a modified polyurethane resin containing initial polymer molecular chain fragments having a chain extension group.

15. The method for preparing a modified polyurethane resin according to claim 11, characterized in that: The temperature of the reduced pressure distillation is 65-95°C, 95-120°C, 120-150°C or 150-200°C; the pressure of the reduced pressure distillation is 0.01-2 mmHg, 2-5 mmHg, 5-20 mmHg, 20-100 mmHg or 100-400 mmHg.

16. The method for preparing a modified polyurethane resin according to claim 1, characterized in that: In the step C, the grafting reaction includes a chemical bonding reaction with a substance containing an active double bond.

17. The method for preparing a modified polyurethane resin according to claim 16, characterized in that: The grafting reaction is an esterification reaction.

18. The method for preparing a modified polyurethane resin according to claim 17, characterized in that: 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; The grafting reaction is an esterification reaction with acrylic acid and / or methacrylic acid.

19. A modified polyurethane resin obtained by the method for preparing a modified polyurethane resin according to any one of claims 1 to 18.

20. A composite material using the modified polyurethane resin according to claim 19 as a matrix.

21. The composite material according to claim 20, characterized in that The composite material comprises the modified polyurethane resin and a reinforcing material, wherein the reinforcing material comprises fibers; The fibers include one or a combination of fiber fabrics, continuous fiber yarns, short-cut fibers, pelletized fibers, powdered fibers or fillers.

22. A method for preparing a composite material according to claim 20, characterized in that: The following steps are involved: Step e, impregnating the modified polyurethane resin into fibers at 0-150° C. to produce a composite material.

23. The method for preparing a composite material according to claim 22, characterized in that: The following steps are also included: Step 1: adding a curing agent to the composite material to carry out a curing reaction to obtain a cured resin; 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, and 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; Free radical initiators include thermosensitive free radical initiators; Thermosensitive free radical initiators include peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds or other suitable free radical initiators that can initiate the curing of double bond-containing compounds.

24. A method for preparing a semi-cured material for curing the modified polyurethane resin using the modified polyurethane resin according to claim 19, characterized in that: The following steps are involved: Step 2: Add a curing agent to the modified polyurethane resin and mix them to obtain a semi-cured material.

25. The method for preparing a semi-cured material according to claim 24, 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, and 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; Free radical initiators include thermosensitive free radical initiators; Thermosensitive free radical initiators include peroxides, persulfides, peroxycarbonates, peroxyboric acid, azo compounds or other suitable free radical initiators that can initiate the curing of double bond-containing compounds.

26. The method for preparing a semi-cured material according to claim 25, characterized in that: The semi-cured material is obtained by a free radical polymerization reaction of the modified polyurethane in the presence of the free radical initiator; 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; 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.

27. The method for preparing a semi-cured material according to claim 24, characterized in that: In step 2, a step of heating the modified polymer is included, wherein the modified polymer is heated to 50°C to 180°C.

28. A semi-cured material obtained according to the method for preparing a semi-cured material according to claim 24.

29. A composite material based on the semi-cured material according to claim 28.

30. The composite material according to claim 29, characterized in that The composite material comprises a semi-cured material and a reinforcing material, and the reinforcing material comprises fibers; The fiber form includes one or a combination of fiber fabric, continuous fiber yarn, short-cut fiber, ball fiber, powder fiber, and filler; The composite material is prepared under reaction conditions where free radical polymerization occurs, and together with the reinforcing material forms a composite material based on the prepreg.

31. Use of the composite material according to claim 20, 21, 22, 23 or 29 in composite prepreg, sheet molding compound (SMC) or bulk molding compound (BMC).

32. A method for preparing a composite material according to claim 29, characterized in that: The following steps are involved: Step g: heating the semi-cured material to 50-160° C. to impregnate the fibers and / or fillers to produce the composite material.

33. The method for preparing a composite material according to claim 32, characterized in that: The composite material comprises a semi-cured material and a reinforcing material, wherein the reinforcing material comprises fibers and / or fillers; The fiber form includes one or a combination of fiber fabric, continuous fiber yarn, short-cut fiber, ball fiber, and powder fiber; The composite material is prepared under reaction conditions where free radical polymerization occurs, and together with the reinforcing material, forms a composite material based on the semi-cured material; The process of impregnating the fiber and / or filler includes: high-speed stirring, centrifugal stirring, screw mixing, rubber roller kneading, stirring and kneading, forming a rubber film composite roll pressing, diluting and then impregnating, composite and then rolling, etc. One or more combinations of the methods; The composite material is prepared by one or more combinations of pultrusion, prepreg, SMC / BMC, winding, resin transfer, vacuum introduction, hand lay-up, compression, and injection molding.

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