Modified nitrile rubber, method for producing the same, and use thereof, and epoxy resin composition

Abstract

The present application relates to the field of epoxy resin modification, discloses a modified nitrile rubber and its preparation method and application, and an epoxy resin composition, the modified nitrile rubber comprises a core, an intermediate layer and an outermost layer polymer;The core includes nitrile rubber particles, the intermediate layer includes conjugated diene polymer, and the outermost layer polymer includes the polymerization product of vinyl monomer and optional crosslinking monomer.This modified nitrile rubber has good dispersibility in epoxy resin, and can improve the low-temperature impact resistance of epoxy resin.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin modification, specifically to a modified nitrile rubber, its preparation method and application, and an epoxy resin composition. Background Technology

[0002] Epoxy resins are widely used in building materials, electronic and electrical materials, adhesives, and fiber-reinforced composites due to their excellent mechanical properties, electrical insulation, heat resistance, adhesion, and processing properties. However, like other thermosetting resins, epoxy resins are brittle. Therefore, toughening modification has always been a key technology for developing high-performance epoxy resin systems.

[0003] Epoxy resins can be toughened by interpenetrating network structures, rubber elastomers, thermoplastics, inorganic rigid fillers, multilayer polymers, thermotropic liquid crystal polymers, nanomaterials, flexible segment curing agents, in-situ polymerization, etc.

[0004] WO01 / 40356A1 discloses a fully vulcanized powdered rubber. In this rubber, the use of carboxylated butadiene-acrylonitrile elastic nanoparticles to toughen epoxy resin produces an extraordinary modification effect, not only superior to existing toughening agents but also maintaining and even improving its heat resistance temperature. However, its impact resistance decreases at low temperatures, thus limiting its application in certain situations. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of poor impact resistance of epoxy resin at low temperatures in the prior art, and to provide a modified nitrile rubber, its preparation method and application, and an epoxy resin composition. The modified nitrile rubber has good dispersibility in epoxy resin and can improve the low-temperature impact resistance of epoxy resin.

[0006] To achieve the above objectives, the first aspect of the present invention provides a modified nitrile rubber, wherein the modified nitrile rubber comprises a core, an intermediate layer and an outermost polymer layer;

[0007] The core comprises nitrile rubber particles, the intermediate layer comprises a conjugated diene polymer, and the outermost polymer comprises a polymer of vinyl monomers and optionally crosslinking monomers.

[0008] Preferably, based on the total mass of the modified nitrile rubber, the core content is 50-90 wt%, more preferably 60-80 wt%, the intermediate layer content is 5-25 wt%, more preferably 5-15 wt%, and the outermost polymer content is 5-35 wt%, more preferably 15-25 wt%.

[0009] Preferably, the modified nitrile rubber has a gel content of 80-99 wt%, more preferably 90-99 wt%.

[0010] Preferably, the modified nitrile rubber has an average particle size of 60-250 nm, more preferably 80-170 nm.

[0011] Preferably, the nitrile rubber particles are radiation-crosslinked nitrile rubber particles.

[0012] Preferably, the average particle size of the nitrile rubber particles is 50-200 nm, and more preferably 50-150 nm.

[0013] Preferably, the gel content of the nitrile rubber particles is greater than 60 wt%, and more preferably 75-99 wt%.

[0014] Preferably, the glass transition temperature of the nitrile rubber particles is not higher than -20°C, and more preferably -60°C to -20°C.

[0015] Preferably, the conjugated diene polymer is obtained by polymerizing conjugated diene monomers.

[0016] Preferably, the conjugated diene monomer is selected from at least one of butadiene, isoprene, and isoprene.

[0017] Preferably, the mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer is 1:0-2, and more preferably 1:0.01-1.

[0018] Preferably, the vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile, and alkyl (meth)acrylate.

[0019] Preferably, the alkyl methacrylate is selected from at least one of methyl methacrylate, methyl acrylate, and ethyl acrylate.

[0020] Preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer.

[0021] Preferably, the crosslinking monomer is selected from at least one of trimellitic acid trimellitate, divinylbenzene, triallyl isocyanurate, and butanediol dimethacrylate.

[0022] A second aspect of the present invention provides a method for preparing modified nitrile rubber, wherein the method includes the following steps:

[0023] (1) A mixture containing conjugated diene monomer and nitrile rubber particles is swollen to obtain a swollen product;

[0024] (2) In the presence of a free radical initiator, the swollen product is subjected to a first polymerization reaction to obtain a first polymerization product in which a conjugated diene polymer intermediate layer is formed on the nitrile rubber particles.

[0025] (3) The first polymerization product is mixed with vinyl monomers and optional crosslinking monomers to carry out a second polymerization reaction, and an outermost polymer formed by the polymerization of vinyl monomers and optional crosslinking monomers is formed on the first polymerization product to obtain modified nitrile rubber.

[0026] Preferably, the mass ratio of the nitrile rubber particles to the conjugated diene monomer is 1:0.05-0.5, more preferably 0.06-0.25.

[0027] Preferably, the mass ratio of the nitrile rubber particles to the vinyl monomer and optional crosslinking monomer is 1:0.05-0.7, more preferably 1:0.2-0.45.

[0028] Preferably, the swelling conditions in step (1) include: a swelling time of 0.5-3h, preferably 1-2h; and a swelling temperature of 30-60℃, preferably 40-55℃.

[0029] Preferably, the conditions for the first polymerization reaction and the second polymerization reaction each independently include: a reaction temperature of 60-90°C, preferably 65-85°C.

[0030] Preferably, the nitrile rubber particles are radiation-crosslinked nitrile rubber particles.

[0031] Preferably, the conditions for the irradiation crosslinking include an irradiation dose of 0.1-30 Mrad, more preferably 0.5-20 Mrad.

[0032] Preferably, the conjugated diene monomer is selected from at least one of butadiene, isoprene, and isoprene.

[0033] Preferably, the free radical initiator is a water-soluble persulfate and / or an organic peroxide.

[0034] Preferably, the amount of the free radical initiator used is 0.1-2 parts, more preferably 0.5-1 parts, based on 100 parts by weight of the total weight of the conjugated diene monomer, vinyl monomer and crosslinking monomer.

[0035] Preferably, the mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer is 1:0-2, and more preferably 1:0.01-1.

[0036] Preferably, the vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile, and alkyl (meth)acrylate.

[0037] Preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer.

[0038] The third aspect of this invention provides a modified nitrile rubber prepared by the preparation method described in the second aspect.

[0039] The fourth aspect of this invention provides an application of the modified nitrile rubber described in the first or third aspect in the field of epoxy resin toughening.

[0040] A fifth aspect of the present invention provides an epoxy resin composition comprising an epoxy resin, a modified nitrile rubber, and a curing agent;

[0041] The modified nitrile rubber is the modified nitrile rubber described in the first or third aspect.

[0042] The beneficial effects achieved through the above technical solution are as follows:

[0043] The modified nitrile rubber provided by this invention has a multilayer polymer structure, exhibits good dispersibility in epoxy resin, shows minimal viscosity increase, facilitates handling, and can improve the low-temperature impact resistance of epoxy resin. Detailed Implementation

[0044] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0045] The first aspect of the present invention provides a modified nitrile rubber, wherein the modified nitrile rubber comprises a core, an intermediate layer and an outermost polymer layer;

[0046] The core comprises nitrile rubber particles, the intermediate layer comprises a conjugated diene polymer, and the outermost polymer comprises a polymer of vinyl monomers and optionally crosslinking monomers.

[0047] In this invention, the modified nitrile rubber is obtained by grafting a conjugated diene polymer onto the surface of nitrile rubber particles, and then grafting an outermost polymer that is compatible with epoxy resin, resulting in a multilayer structure. This modified nitrile rubber exhibits good dispersibility in epoxy resin and can also improve the low-temperature impact resistance of epoxy resin.

[0048] According to the present invention, preferably, based on the total mass of the modified nitrile rubber, the content of the core is 50-90 wt%, more preferably 60-80 wt%, the content of the intermediate layer is 5-25 wt%, more preferably 5-15 wt%, and the content of the outermost polymer is 5-35 wt%, more preferably 15-25 wt%.

[0049] In this invention, the content of the core, intermediate layer and outermost layer polymer of the modified nitrile rubber is calculated based on the feed ratio of the raw materials used to prepare the core, intermediate layer and outermost layer polymer.

[0050] In this invention, the core layer provides toughness; a low content will result in insufficient overall toughness of the material. The middle layer regulates low-temperature performance; a low content will lead to poor low-temperature performance. The outermost polymer layer ensures compatibility with the substrate; a low content will result in uneven particle dispersion. The amount of each of the three layers must not be too high, otherwise the other layers will not function effectively.

[0051] According to the present invention, preferably, the modified nitrile rubber has a gel content of 80-99 wt%, more preferably 90-99 wt%. In the present invention, the high gel content of the modified nitrile rubber helps to reduce its viscosity.

[0052] According to the present invention, preferably, the average particle size of the modified nitrile rubber is 60-250 nm, for example, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 120 nm, 150 nm, 170 nm, 200 nm, 220 nm, 250 nm, or any range between the two, preferably 80-170 nm. The average particle size is determined using a Malvern Zetasizer 3000HSA laser particle size analyzer.

[0053] According to the present invention, preferably, the nitrile rubber particles are radiation-crosslinked nitrile rubber particles.

[0054] According to the present invention, preferably, the irradiation crosslinking method used for the irradiated crosslinked nitrile rubber particles is not particularly limited; preferably, a high-energy ray source is used to irradiate the nitrile rubber latex. The high-energy ray source used for the irradiation crosslinking is selected from at least one of a cobalt source, ultraviolet light, and a high-energy electron accelerator.

[0055] According to a preferred embodiment of the present invention, the irradiated crosslinked nitrile rubber particles are crosslinked with nitrile rubber latex using the irradiation method disclosed in WO01 / 40356A1, thereby increasing the gel content in the nitrile rubber latex.

[0056] In this invention, preferably, the irradiation dose for the irradiation crosslinking is 0.1-30 Mrad, more preferably 0.5-20 Mrad.

[0057] In this invention, preferably, the nitrile rubber latex is irradiated and crosslinked before drying to obtain irradiated crosslinked nitrile rubber particles. The drying method and conditions are not particularly limited.

[0058] In this invention, preferably, the composition of the nitrile rubber particles includes: butadiene monomer, acrylonitrile monomer, and optionally a vinyl unsaturated carboxylic acid monomer. The vinyl unsaturated carboxylic acid monomer is selected from at least one of acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid.

[0059] In this invention, preferably, based on the total weight of the nitrile rubber particles, the content of the butadiene monomer is 50-95 wt%, more preferably 70-90 wt%, the content of the acrylonitrile monomer is 5-50 wt%, more preferably 10-30 wt%, and the content of the vinyl unsaturated carboxylic acid monomer is 0-10 wt%, more preferably 0-5 wt%.

[0060] According to the present invention, preferably, the average particle size of the nitrile rubber particles is 50-200 nm, more preferably 50-150 nm. The average particle size of the nitrile rubber particles is determined using a Malvern Zetasizer 3000HSA laser particle size analyzer.

[0061] According to the present invention, preferably, the gel content of the nitrile rubber particles is greater than 60 wt%, more preferably 75-99 wt%. The method for testing the gel content of the modified nitrile rubber and nitrile rubber particles in the present invention is as follows: a certain amount of latex is extracted with ethanol and dried; approximately 0.2 g of the dry sample (mass m1) is placed in a stainless steel mesh cage; the mesh cage is immersed in a wide-mouth bottle containing 50 mL of toluene and left to stand for 24 hours; the mesh cage is removed, the toluene solvent is evaporated, and the sample is dried in a vacuum oven at 100°C for 2 hours, cooled to room temperature, and the mass (m2) is measured. The latex gel mass fraction is then calculated as m2 / m1.

[0062] According to the present invention, preferably, the glass transition temperature of the nitrile rubber particles is not higher than -20°C, and more preferably between -60°C and -20°C. The glass transition temperature of the nitrile rubber particles is determined by differential scanning calorimetry (DSC).

[0063] According to the present invention, preferably, the conjugated diene polymer is obtained by polymerization of conjugated diene monomers.

[0064] According to the present invention, the conjugated diene monomer is a conventional conjugated diene monomer in the art. Preferably, the conjugated diene monomer is selected from at least one of butadiene, isoprene, and isoprene.

[0065] In this invention, the polymer obtained by grafting conjugated diene monomers onto the surface of nitrile rubber particles can improve the low-temperature performance of the particles and enhance the mechanical properties of the modified nitrile rubber at low temperatures.

[0066] According to the present invention, preferably, the mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer is 1:0-2, for example, 1:0.01, 1:0.02, 1:0.05, 1:0.08, 1:0.1, 1:0.15, 1:0.2, 1:0.3, 1:0.5, 1:0.8, 1:1, or any range between the two, preferably 1:0.01-1. In the present invention, the mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer satisfies the above range. The polymerized product, as the outermost layer of modified nitrile rubber, can improve the low-temperature impact resistance of nitrile rubber, has good compatibility with epoxy resin, can improve the dispersibility of modified nitrile rubber in epoxy resin, and further can improve the mechanical properties of the epoxy resin composition.

[0067] According to the present invention, the vinyl monomer is a vinyl monomer conventional in the art. Preferably, the vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile, and alkyl (meth)acrylates.

[0068] According to the present invention, preferably, the (meth)acrylate alkyl ester is selected from at least one of methyl methacrylate, methyl acrylate and ethyl acrylate.

[0069] According to the present invention, preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer. The crosslinking monomer is not included in the range defined by the vinyl monomer.

[0070] In this invention, preferably, the poly(meth)acrylate monomers are selected from at least one of diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, neopentyl glycol (meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, and pentaerythritol tetra(meth)acrylate ethoxylate.

[0071] In this invention, preferably, the divinyl monomer is selected from at least one of divinylbenzene, divinylnaphthalene, tripropylene trimellitate, and trivinylbenzene. The divinyl monomer contains at least two vinyl groups.

[0072] In this invention, preferably, the crosslinking monomer is selected from at least one of trimellitic acid trimellitate, divinylbenzene, triallyl isocyanurate, and butanediol dimethacrylate.

[0073] A second aspect of the present invention provides a method for preparing modified nitrile rubber, wherein the method includes the following steps:

[0074] (1) A mixture containing conjugated diene monomer and nitrile rubber particles is swollen to obtain a swollen product;

[0075] (2) In the presence of a free radical initiator, the swollen product is subjected to a first polymerization reaction to obtain a first polymerization product in which a conjugated diene polymer intermediate layer is formed on the nitrile rubber particles.

[0076] (3) The first polymerization product is mixed with vinyl monomers and optional crosslinking monomers to carry out a second polymerization reaction, and an outermost polymer formed by the polymerization of vinyl monomers and optional crosslinking monomers is formed on the first polymerization product to obtain modified nitrile rubber.

[0077] In this invention, the modified nitrile rubber has nitrile rubber particles as the core, a conjugated diene polymer as the intermediate layer, and a polymer formed by the polymerization of vinyl monomers and optional crosslinking monomers as the outermost polymer.

[0078] In this invention, the preparation method of the modified nitrile rubber is simple and the operation steps are convenient. The obtained modified nitrile rubber has good dispersibility in epoxy resin. After being mixed with epoxy resin, it can improve the low-temperature impact resistance of epoxy resin.

[0079] According to the present invention, preferably, the nitrile rubber particles are radiation-crosslinked nitrile rubber particles.

[0080] According to the present invention, preferably, the conditions for radiation crosslinking include an irradiation dose of 0.1-30 Mrad, more preferably 0.5-20 Mrad. The preparation method and performance parameters of the nitrile rubber particles in this invention have been described above and will not be repeated here.

[0081] According to the present invention, preferably, the conjugated diene monomer is selected from at least one of butadiene, isoprene and isoprene.

[0082] According to the present invention, preferably, the mass ratio of the nitrile rubber particles to the conjugated diene monomer is 1:0.05-0.5, for example, 1:0.05, 1:0.06, 1:0.08, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.5, or any range between the two, preferably 0.06-0.25.

[0083] According to the present invention, preferably, the mass ratio of the nitrile rubber particles to the vinyl monomer and optionally the crosslinking monomer is 1:0.05-0.7, for example, 1:0.05, 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45, 1:0.5, 1:0.6, 1:0.7, or any range between the two, preferably 1:0.2-0.45.

[0084] In this invention, the swelling method is not particularly limited. According to a preferred embodiment of the invention, a mixture of a first emulsifier, nitrile rubber particles and conjugated diene monomer is heated to induce swelling.

[0085] According to the present invention, preferably, the swelling conditions in step (1) include: a swelling time of 0.5-3h, preferably 1-2h; and a swelling temperature of 30-60℃, preferably 40-55℃.

[0086] In this invention, the type and source of the first emulsifier are not particularly limited; it is a conventional emulsifier in the art, which can be commercially available or prepared using existing methods. Preferably, the first emulsifier is an anionic surfactant and / or a nonionic surfactant, preferably selected from at least one of fatty acid soaps, rosin acid soaps, alkyl sulfates, alkyl sulfonates, and fatty alcohol polyoxyethylene ethers. Specifically, sodium dodecylbenzenesulfonate is preferred.

[0087] In this invention, preferably, the amount of the first emulsifier used is 0.01-2 parts by weight, more preferably 0.1-1 parts by weight, based on 100 parts by weight of the total weight of the conjugated diene monomers.

[0088] In this invention, preferably, a first auxiliary agent is added during the swelling process. The type of the first auxiliary agent is not particularly limited, and it is a conventional swelling-promoting compound in the art, preferably selected from at least one of disodium ethylenediaminetetraacetate, n-butanol, propylene glycol, and glycerol. Preferably, the first emulsifier and the first auxiliary agent are of different types. In this invention, the addition of the above-mentioned auxiliary agent can complex metal impurity ions.

[0089] In this invention, the amount of the first auxiliary agent used is not particularly limited. Those skilled in the art can adjust the amount of the first auxiliary agent used according to the emulsification situation. Preferably, based on the total weight of the conjugated diene monomers as 100 parts by weight, the amount of the first auxiliary agent used is 0-0.5 parts by weight, preferably 0.02-0.3 parts by weight.

[0090] In this invention, preferably, the second polymerization reaction is carried out in the presence of a second emulsifier. The type and amount of the second emulsifier may be the same as or different from that of the first emulsifier.

[0091] In this invention, preferably, the amount of the second emulsifier added is 0-1 parts by weight, more preferably 0.01-0.1 parts by weight, based on a total weight of 100 parts by weight of the vinyl monomer and the crosslinking monomer.

[0092] According to the present invention, preferably, the reaction conditions for the first polymerization reaction and the second polymerization reaction each independently include: a reaction temperature of 60-90°C, preferably 65-85°C.

[0093] According to the present invention, preferably, the first polymerization reaction and the second polymerization reaction are stopped when the conversion rate reaches 99%. Preferably, the polymerization reaction is carried out in a batch manner.

[0094] In this invention, preferably, a second auxiliary agent is optionally added during the second polymerization reaction. The type of the second auxiliary agent is not particularly limited, and it may be the same as or different from the type of the first auxiliary agent. Preferably, it is selected from at least one of disodium ethylenediaminetetraacetate, n-butanol, propylene glycol, and glycerol.

[0095] In this invention, the amount of the second auxiliary agent used is not particularly limited. Preferably, based on the total weight of the vinyl monomer and the crosslinking monomer as 100 parts by weight, the amount of the second auxiliary agent used is 0-0.5 parts by weight, preferably 0.02-0.3 parts by weight.

[0096] In this invention, the polymerization reaction method and equipment are not particularly limited, as long as the polymerization effect can be achieved. Those skilled in the art can choose conventional polymerization reaction methods and equipment. Preferably, the polymerization reaction is carried out in a polymerization reactor. Preferably, emulsion polymerization is used for the polymerization reaction.

[0097] According to the present invention, the type of free radical initiator is not particularly limited, and those skilled in the art can choose conventional free radical initiators. Preferably, the free radical initiator is a water-soluble persulfate and / or an organic peroxide.

[0098] In this invention, preferably, the water-soluble persulfate is selected from at least one of potassium persulfate, sodium persulfate, and ammonium persulfate.

[0099] In this invention, preferably, the organic peroxide is selected from at least one of benzoyl peroxide, tert-butyl hydroperoxide, cumene peroxide, and dicumene peroxide.

[0100] According to the present invention, the amount of the free radical initiator used is not particularly limited, as long as it is sufficient to initiate the polymerization reaction. Preferably, based on 100 parts by weight of the total weight of the conjugated diene monomer, vinyl monomer, and crosslinking monomer, the amount of the free radical initiator used is 0.1-2 parts, more preferably 0.5-1 parts.

[0101] In this invention, preferably, the free radical initiator can be added together in the first polymerization reaction, or it can be added separately in the first polymerization reaction and the second polymerization reaction.

[0102] According to a preferred embodiment of the present invention, the free radical initiator is added in both the first polymerization reaction and the second polymerization reaction. The type and amount of the free radical initiator added in the second polymerization reaction may be the same as or different from those in the first polymerization reaction, and can be adjusted adaptively by those skilled in the art based on the circumstances of the first and second polymerization reactions. Preferably, the mass ratio of the amounts of free radical initiators used in the first polymerization reaction and the second polymerization reaction is 1:0.5-2.

[0103] In this invention, preferably, the first polymerization reaction and the second polymerization reaction are carried out in the presence of a solvent. Preferably, the solvent is deionized water.

[0104] In this invention, the amount of deionized water used is not particularly limited. Preferably, based on 100 parts by weight of the total weight of the conjugated diene monomer, vinyl monomer, and crosslinking monomer, the amount of deionized water used is 10-200 parts by weight, more preferably 40-150 parts by weight. Those skilled in the art can adapt the amount of deionized water used for the first and second polymerization reactions according to the polymerization reaction conditions.

[0105] According to the present invention, preferably, the mass ratio of vinyl monomer to crosslinking monomer in the outermost polymer is 1:0-2, more preferably 1:0.01-1.

[0106] According to the present invention, preferably, the vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile and alkyl (meth)acrylate.

[0107] According to the present invention, preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer.

[0108] In this invention, the types and amounts of the vinyl monomers and crosslinking monomers are described in the foregoing specification and will not be repeated here.

[0109] The third aspect of this invention provides a modified nitrile rubber prepared by the preparation method described in the second aspect.

[0110] The fourth aspect of this invention provides an application of the modified nitrile rubber described in the first or third aspect in the field of epoxy resin toughening.

[0111] A fifth aspect of the present invention provides an epoxy resin composition comprising an epoxy resin, a modified nitrile rubber, and a curing agent;

[0112] The modified nitrile rubber is the modified nitrile rubber described in the first or third aspect.

[0113] In this invention, the preparation method of the epoxy resin composition is not particularly limited; those skilled in the art can simply disperse the modified nitrile rubber into the epoxy resin. Preferably, an emulsion mixing method and / or a powder dispersion method are used.

[0114] According to the present invention, preferably, the mass ratio of the epoxy resin to the modified nitrile rubber is 0.01-0.5, more preferably 1:0.05-0.3.

[0115] In this invention, the emulsion mixing method includes: mixing modified nitrile rubber emulsion with epoxy resin and then removing the solvent.

[0116] In this invention, the powder dispersion method includes: drying a modified nitrile rubber emulsion to obtain modified nitrile rubber, and then dispersing it in an epoxy resin. The drying method is not particularly limited, but spray drying and / or coagulation water washing drying are preferred.

[0117] In this invention, the type and amount of curing agent are not particularly limited, and those skilled in the art can adjust them adaptably according to the mixing of the epoxy resin composition. Preferably, the curing agent is methyltetrahydrophthalic anhydride and / or triethanolamine.

[0118] In this invention, preferably, the mass ratio of the curing agent to the epoxy resin is 0.2-1.5:1, more preferably 0.4-1.2:1.

[0119] In this invention, the modified nitrile rubber exhibits good dispersibility in epoxy resin with minimal viscosity increase, facilitating handling. Upon further curing, it displays excellent mechanical properties and enhances the low-temperature impact resistance of the epoxy resin composition.

[0120] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available.

[0121] The method for testing the viscosity of the epoxy resin composition is as follows: the viscosity of the epoxy resin composition is measured at 50°C using a Brookfield digital viscometer.

[0122] Test method for cantilever beam unnotched impact strength of epoxy resin compositions: GB / T1843;

[0123] The content of the core, intermediate layer and outermost layer polymers of the modified nitrile rubber is calculated based on the feed ratio of the raw materials used to prepare the core, intermediate layer and outermost layer polymers.

[0124] Example 1

[0125] Preparation of nitrile rubber particles

[0126] The composition of nitrile rubber latex: butadiene 80wt%, acrylonitrile 20wt%.

[0127] 150 parts by weight of nitrile rubber latex were crosslinked by irradiation with a cobalt source at a dose of 10 Mrad to obtain nitrile rubber particle latex with a nitrile rubber particle content of 40 wt%, an average particle size of 90 nm, a gel content of 85 wt%, and a glass transition temperature of -40 °C.

[0128] (1) Graft polymerization of the intermediate layer: The types and amounts of raw materials added are shown in Table 1. Deionized water, disodium ethylenediaminetetraacetate (disodium), and sodium dodecylbenzenesulfonate (emulsifier) ​​are added to the polymerization reactor. Nitrile rubber particles and conjugated diene monomers are added under stirring. The temperature is raised to 50°C and maintained for 1 hour, so that some of the monomers swell into the nitrile rubber particles to obtain the swollen product.

[0129] (2) First polymerization reaction: The swollen product is heated to 65°C, and 0.2 parts by weight of sodium persulfate is added to initiate the first polymerization reaction. The reaction is terminated when the monomer polymerization conversion rate reaches more than 99%, and the first polymer product is obtained.

[0130] (3) Second polymerization reaction: Deionized water, disodium ethylenediaminetetraacetate (EDTA), sodium dodecylbenzenesulfonate (EDS) emulsifier, vinyl monomers, and crosslinking monomers are added to the polymerization reactor. The temperature is raised to 50°C and maintained for 1 hour to allow some monomers to swell. The temperature is then raised to 65°C, and 0.2 parts by weight of sodium persulfate is added to initiate the second polymerization reaction. The reaction is terminated when the monomer polymerization conversion rate reaches 99% or higher, yielding modified nitrile rubber.

[0131] Examples 2-6

[0132] Modified nitrile rubber was prepared according to the method in Example 1, except that the amount and type of each raw material were adjusted as shown in Table 1 to obtain modified nitrile rubber.

[0133] Table 1

[0134]

[0135] Example 7

[0136] Conventional nitrile rubber is used. The composition of nitrile rubber latex is: butadiene 80wt% and acrylonitrile 20wt%.

[0137] The nitrile rubber granules contain 42 wt% of nitrile rubber, with an average particle size of 100 nm, a gel content of 95 wt%, and a glass transition temperature of -35℃.

[0138] (1) Graft polymerization of the intermediate layer: 15 parts by weight of deionized water, 0.008 parts by weight of ethylenediaminetetraacetic acid disodium (disodium) and 0.03 parts by weight of sodium dodecylbenzenesulfonate (emulsifier) ​​were added to the polymerization kettle. 75 parts by weight of nitrile rubber particles and 10 parts by weight of butadiene monomer were added under stirring. The temperature was raised to 50°C and maintained for 1 hour to allow some of the monomer to swell into the nitrile rubber particles to obtain the swollen product.

[0139] (2) First polymerization reaction: The swollen product is heated to 67°C, and 0.2 parts by weight of sodium persulfate (initiator) is added to start the first polymerization reaction. When the polymerization conversion rate of the monomer reaches more than 99%, the reaction is stopped to obtain the first polymerization product.

[0140] (3) Second polymerization reaction: 22.5 parts by weight of deionized water, 0.045 parts by weight of sodium dodecylbenzenesulfonate (emulsifier), 12 parts by weight of methyl methacrylate monomer, and 3 parts by weight of trimellitic acid tripropylene crosslinking monomer were added to the polymerization reactor. The temperature was raised to 50°C and maintained for 1 hour to allow some monomers to swell into the latex particles. The temperature was then raised to 65°C, and 0.2 parts by weight of sodium persulfate (initiator) was added to initiate the second polymerization reaction. The reaction was terminated when the monomer polymerization conversion rate reached over 99%, yielding modified nitrile rubber.

[0141] Comparative Example 1

[0142] The irradiated crosslinked nitrile latex prepared in Example 1 was used as Comparative Example 1.

[0143] Comparative Example 2

[0144] Modified nitrile rubber was prepared according to the method of Example 1, except that in step (1), an equal part by weight of styrene was added to replace the conjugated diene monomer, and the types and parts by weight of other raw materials were the same as in Example 1, thus obtaining modified nitrile rubber.

[0145] Comparative Example 3

[0146] Modified nitrile rubber was prepared according to the method of Example 1, except that the second polymerization reaction in step (3) was not carried out. The types and weight parts of other raw materials were the same as in Example 1, and the first polymerization product was used as the modified nitrile rubber.

[0147] Table 2

[0148] Average particle size, nm Gel content, wt% Example 1 96 93 Example 2 95 97 Example 3 97 95 Example 4 92 94 Example 5 91 92 Example 6 100 76 Example 7 105 95 Comparative Example 1 90 85 Comparative Example 2 95 90 Comparative Example 3 92 93

[0149] As can be seen from Table 2, the average particle size and gel content of the modified nitrile rubber prepared in the embodiments of the present invention are higher than those of the nitrile rubber in Comparative Example 1, indicating that the polymers of the middle layer and the outermost layer have been grafted onto the core.

[0150] Application examples

[0151] 100 parts by weight of epoxy resin CYD128 (a product of Baling Petrochemical), modified nitrile rubber prepared in the examples and comparative examples, 70 parts by weight of curing agent methyltetrahydrophthalic anhydride, and 12 parts by weight of triethanolamine were mixed using a vacuum degassing mixer (manufactured by Shenzhen Yiyi Automation Equipment Co., Ltd., AD-2000A) to obtain an epoxy resin composition. Low-temperature testing conditions: Test pieces were prepared and tested at a certain temperature according to the method of GB / T1843. The physical property evaluation results of the examples and comparative examples are shown in Table 3.

[0152] Table 3

[0153]

[0154] As can be seen from the results in Table 3, when the modified nitrile rubber prepared in the examples is added to the epoxy resin to obtain the epoxy resin composition, the viscosity of the epoxy resin composition changes little, and it has high impact strength at both 25℃ and -40℃. This indicates that adding modified nitrile rubber to the epoxy resin can significantly improve the mechanical properties of the epoxy resin.

[0155] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A modified nitrile butadiene rubber, characterized in that, The modified nitrile rubber comprises a core, an intermediate layer, and an outermost polymer layer; The core comprises nitrile rubber particles, the intermediate layer comprises a conjugated diene polymer, and the outermost polymer comprises a polymer of vinyl monomers and optionally crosslinking monomers.

2. The modified nitrile rubber according to claim 1, wherein, Based on the total mass of the modified nitrile rubber, the content of the core is 50-90 wt%, preferably 60-80 wt%, the content of the intermediate layer is 5-25 wt%, preferably 5-15 wt%, and the content of the outermost polymer is 5-35 wt%, preferably 15-25 wt%. Preferably, the modified nitrile rubber has a gel content of 80-99 wt%, more preferably 90-99 wt%. Preferably, the modified nitrile rubber has an average particle size of 60-250 nm, more preferably 80-170 nm.

3. The modified nitrile rubber according to claim 1 or 2, wherein, The nitrile rubber particles are irradiated crosslinked nitrile rubber particles; Preferably, the average particle size of the nitrile rubber particles is 50-200 nm, more preferably 50-150 nm; Preferably, the gel content of the nitrile rubber particles is greater than 60 wt%, and more preferably 75-99 wt%. Preferably, the glass transition temperature of the nitrile rubber particles is not higher than -20°C, and more preferably -60°C to -20°C.

4. The modified nitrile rubber according to any one of claims 1-3, wherein, The conjugated diene polymer is obtained by polymerizing conjugated diene monomers; Preferably, the conjugated diene monomer is selected from at least one of butadiene, isoprene, and isoprene.

5. The modified nitrile rubber according to any one of claims 1-4, wherein, The mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer layer is 1:0-2, preferably 1:0.01-1.

6. The modified nitrile rubber according to any one of claims 1-5, wherein, The vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile, and alkyl (meth)acrylates; Preferably, the alkyl (meth)acrylate is selected from at least one of methyl methacrylate, methyl acrylate, and ethyl acrylate; Preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer; Preferably, the crosslinking monomer is selected from at least one of trimellitic acid trimellitate, divinylbenzene, triallyl isocyanurate, and butanediol dimethacrylate.

7. A method for preparing modified nitrile butadiene rubber, characterized in that, The method includes the following steps: (1) A mixture containing conjugated diene monomer and nitrile rubber particles is swollen to obtain a swollen product; (2) In the presence of a free radical initiator, the swollen product is subjected to a first polymerization reaction to obtain a first polymerization product in which a conjugated diene polymer intermediate layer is formed on the nitrile rubber particles. (3) The first polymerization product is mixed with vinyl monomers and optional crosslinking monomers to carry out a second polymerization reaction, and an outermost polymer formed by the polymerization of vinyl monomers and optional crosslinking monomers is formed on the first polymerization product to obtain modified nitrile rubber.

8. The preparation method according to claim 7, wherein, The mass ratio of the nitrile rubber particles to the conjugated diene monomer is 1:0.05-0.5, preferably 0.06-0.25; Preferably, the mass ratio of the nitrile rubber particles to the vinyl monomer and optional crosslinking monomer is 1:0.05-0.7, more preferably 1:0.2-0.

45.

9. The preparation method according to claim 7 or 8, wherein, The swelling conditions described in step (1) include: a swelling time of 0.5-3 h, preferably 1-2 h; and a swelling temperature of 30-60 °C, preferably 40-55 °C. Preferably, the conditions for the first polymerization reaction and the second polymerization reaction each independently include: a reaction temperature of 60-90°C, preferably 65-85°C.

10. The preparation method according to any one of claims 7-9, wherein, The nitrile rubber particles are irradiated crosslinked nitrile rubber particles; Preferably, the conditions for the irradiation crosslinking include an irradiation dose of 0.1-30 Mrad, more preferably 0.5-20 Mrad.

11. The preparation method according to any one of claims 7-10, wherein, The conjugated diene monomer is selected from at least one of butadiene, isoprene and isoprene; Preferably, the free radical initiator is a water-soluble persulfate and / or an organic peroxide; Preferably, the amount of the free radical initiator used is 0.1-2 parts, more preferably 0.5-1 parts, based on 100 parts by weight of the total weight of the conjugated diene monomer, vinyl monomer and crosslinking monomer.

12. The preparation method according to any one of claims 7-11, wherein, The mass ratio of vinyl monomers to crosslinking monomers in the outermost polymer layer is 1:0-2, preferably 1:0.01-1; Preferably, the vinyl monomer is selected from at least one of butadiene, styrene, acrylonitrile, and alkyl (meth)acrylate; Preferably, the crosslinking monomer is a divinyl monomer and / or a poly(meth)acrylate monomer.

13. Modified nitrile rubber prepared by the preparation method according to any one of claims 7-12.

14. The application of the modified nitrile rubber according to any one of claims 1-6 and 13 in the field of epoxy resin toughening.

15. An epoxy resin composition, characterized in that, The epoxy resin composition comprises epoxy resin, modified nitrile rubber, and a curing agent; The modified nitrile rubber is the modified nitrile rubber according to any one of claims 1-6 and claim 13.

16. The epoxy resin composition according to claim 15, wherein, The mass ratio of epoxy resin to modified nitrile rubber is 0.01-0.5, preferably 1:0.05-0.3.

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