CN117903395A

CN117903395A - Polyurethane modified epoxy resin and application thereof

Info

Publication number: CN117903395A
Application number: CN202311318151.7A
Authority: CN
Inventors: 服部公一
Original assignee: Nippon Steel and Sumikin Chemical Co Ltd
Current assignee: Nippon Steel Chemical and Materials Co Ltd
Priority date: 2022-10-18
Filing date: 2023-10-12
Publication date: 2024-04-19
Also published as: TW202417541A; JP2024059456A

Abstract

The invention relates to polyurethane modified epoxy resin and application thereof. An epoxy resin composition characterized by comprising a specific polyurethane-modified epoxy resin (A), a polyurethane-unmodified epoxy resin (B) and a hardener (C) as essential components, wherein the epoxy resin composition comprises 20 to 70 wt% of the component (A), 30.0 to 80.0 wt% of the component (B) and 0.1 to 20.0 wt% of the component (C) relative to the whole composition, and a cured product using the epoxy resin composition.

Description

Polyurethane modified epoxy resin and application thereof

Technical Field

The present invention relates to an epoxy resin composition having excellent properties such as impregnation into a fibrous base material, heat resistance and mechanical properties, and a cured product or the like using the epoxy resin composition.

Background

In recent years, fiber-reinforced composite materials using carbon fibers, glass fibers, aramid fibers, or other structural fibers as reinforcing fibers exhibit excellent specific strength and specific elastic modulus, and are used for structural materials for boats, automobiles, and the like, sporting goods for tennis rackets, golf clubs, fishing poles, and the like, and general industrial applications.

As a method for producing a fiber-reinforced composite material, a method of injecting an uncured matrix resin into reinforcing fibers to form a sheet-like prepreg intermediate and curing the prepreg intermediate, a transfer molding method of injecting a liquid resin into reinforcing fibers set in a mold to produce an intermediate and curing the intermediate, and the like are used. As the resin used in these molding methods, epoxy resins are generally used in terms of excellent heat resistance, adhesion, and mechanical strength. In recent years, with the expansion of the application of fiber-reinforced composite materials to structural members, there has been an increasing demand for further weight reduction of the members, and there has also been a demand for higher performance of epoxy resins used for prepregs. Specifically, by increasing the elastic modulus or stress strength of the cured epoxy resin in a tensile test or a bending test, a fiber-reinforced composite material having light weight and high performance can be designed.

Patent document 1 discloses the following technique: the combination of the multifunctional bisphenol epoxy resin and the amine epoxy resin gives a cured epoxy resin having both flexural modulus and breaking strength.

Patent document 2 discloses the following technique: the elastic modulus of the cured epoxy resin is improved by using an amine-type epoxy resin having a trifunctional or higher structure and a bisphenol F-type epoxy resin having a high molecular weight.

Further, patent document 3 discloses the following technique: the elastic modulus of the epoxy resin cured product is improved by curing an aminophenol type epoxy resin with an aromatic amine compound.

On the other hand, with the recent expansion of the use of carbon fibers, the molding method has also tended to expand. Among them, the filament winding method is suitable for manufacturing hollow containers such as pressure vessels or cylinders. In view of productivity and quality, a method using a narrow intermediate substrate called a tow prepreg, a yarn prepreg, a strand prepreg, or the like, in which a thermosetting resin is impregnated in advance into a reinforcing fiber bundle, has been attracting attention in addition to a conventional wet method. In addition, from the viewpoint of productivity, a drawing molding method is also attracting attention in which a matrix resin is impregnated into a reinforcing fiber bundle by a resin bath containing a liquid matrix resin, and then the reinforcing fiber bundle is continuously drawn and cured by a drawing machine by an extrusion die and a heating die.

In applications such as pressure vessels where a tow prepreg is suitably used, there is an increasing demand for further weight reduction of the member, and there is a demand for higher elasticity and higher strength of the resin, adhesion of fiber interfaces, and the like. If a resin or an elastomer having a highly crosslinked structure is used for the purpose of increasing the elasticity or strength of the resin, the viscosity of the resin composition increases, and the impregnation into the fibers becomes insufficient. In addition, if a large amount of rubber components or core-shell rubber particles are contained in order to improve the adhesion of the fiber interface, there is a possibility that the viscosity of the resin composition increases and the impregnation into the fibers becomes insufficient as well.

In addition, in the drawing molding method as well, in view of resin impregnation and die drawing, low viscosity and rapid hardening property are required, and there is a problem that use of a resin or elastomer component, a rubber component or core-shell rubber particles with high viscosity is limited.

As for the polyurethane-modified epoxy resin, for example, patent document 4 and patent document 5 disclose diglycidyl ether of bisphenol a-alkylene oxide adduct (a), and an epoxy resin/polyurethane mixture (B) containing an epoxy resin and a polyurethane dispersed in the epoxy resin, wherein the polyurethane is obtained by reacting a polyisocyanate compound with a hardening agent capable of reacting with the polyisocyanate compound in the epoxy resin.

Patent document 6 discloses a resin composition containing a compound having an epoxy group and a polyurethane having a structural unit represented by the general formula (II) in the molecule.

Patent document 7 discloses a polyurethane-modified epoxy resin obtained by modifying a bisphenol-type epoxy resin (a) with a medium-high molecular weight polyol compound (b), a polyisocyanate compound (c) and a low molecular weight polyol compound (d) as a chain length extender, using a predetermined amount of the epoxy resin (a), reacting the medium-high molecular weight polyol compound (b) with the polyisocyanate compound (c) in a predetermined amount, and then adding a predetermined amount of the low molecular weight polyol compound (d).

Patent document 8 discloses a polycarbonate-modified epoxy resin in which a hydroxyl group-containing epoxy resin (a), a polyisocyanate compound (B), and a polycarbonate polyol (C) are used as necessary reaction raw materials, and the polycarbonate polyol (C) is a predetermined amount.

Patent document 9 discloses an epoxy resin composition for a fiber-reinforced composite material, which is obtained by blending an epoxy resin (a), a urethane prepolymer (B) having a structure derived from a polyether polyol and having isocyanate groups or hydroxyl groups at both ends of a molecular chain, and a hardener (C), wherein (a) and (B) are compatible before the hardening reaction, and (a) form a sea structure after the hardening reaction, and (B) form an island structure, and a cured product of the obtained epoxy resin composition has a sea-island phase separation structure.

Patent document 10 proposes a polyurethane elastomer in which a diphenylmethane diisocyanate is used as a polyisocyanate compound, a polycarbonate diol is used as a polyol, and three components having specific molecular weight ranges such as propylene oxide adducts of a diol, a polyether polyol, and glycerin are used as a hardener in combination, thereby improving mechanical strength, low compressive strain, low rebound resilience, water resistance, and the like.

Patent document 11 proposes a polyurethane elastomer using a main agent obtained by reacting a polycarbonate diol, a polyether polyol, and a polyisocyanate compound, and a hardener such as1, 4-butanediol, as a polyurethane elastomer having improved flexibility, strength, and water resistance.

Patent document 12 proposes a polycarbonate diol obtained by combining a linear diol with a branched or cyclic diol having an isosorbide structure.

Patent document 13 proposes a polycarbonate resin composition comprising a polycarbonate resin and a soft styrene resin, wherein the polycarbonate resin comprises a structure derived from an isosorbide compound and a structure derived from an alicyclic dihydroxy compound.

Patent document 14 proposes a polyurethane-modified epoxy resin having a polycarbonate structure and a composition using the polyurethane-modified epoxy resin.

However, in these patent documents 4 to 6, urethane is used to improve toughness or wettability with fibers or additives or interfacial adhesion by being incorporated into the structure of epoxy and compatible with epoxy. In addition, in urethane-modified epoxy resins such as patent documents 7 to 11, the use of a polyol having a specific structure has not been satisfactory for the purpose of improving elongation and toughness. Patent documents 12 to 13 propose a polycarbonate diol having a structure derived from an isosorbide compound and a resin composition thereof, but use as a urethane or as a polycarbonate resin is only suggested, and use as a urethane-modified epoxy resin is not suggested. Patent document 14 discloses an improvement in impact resistance and an improvement in fracture toughness by phase separation, but the flexural strength and flexural modulus of elasticity may not sufficiently satisfy the required properties, and the viscosity of the composition itself is high, which makes it impossible to apply the composition to a filament winding method or a drawing forming method.

[ Prior Art literature ]

[ Patent literature ]

[ Patent document 1] Japanese patent laid-open No. 2017-226755

[ Patent document 2] Japanese patent laid-open publication No. 2012-197413

[ Patent document 3] Japanese patent laid-open No. 2010-275493

[ Patent document 4] Japanese patent laid-open No. 2007-284467

[ Patent document 5] Japanese patent laid-open No. 2007-284474

Patent document 6 Japanese patent laid-open No. 2007-224144

[ Patent document 7] Japanese patent No. 6547999

[ Patent document 8] Japanese patent laid-open No. 2017-226717

[ Patent document 9] Japanese patent No. 6593636

[ Patent document 10] Japanese patent laid-open No. 2013-163778

[ Patent document 11] Japanese patent No. 6341405

[ Patent document 12] Japanese patent 6465132

[ Patent document 13] Japanese patent 6519611

[ Patent document 14] WO2021/060226 publication

Disclosure of Invention

[ Problem to be solved by the invention ]

The present invention provides a polyurethane modified epoxy resin having a low viscosity suitable for a filament winding method or a drawing forming method, a rapid hardening property, and a high elasticity and a high strength at a relatively slow hardening temperature of about 120 ℃ to 160 ℃ and a composition thereof.

That is, the present invention is to provide a novel polyurethane-modified epoxy resin composition, a cured product thereof, and the like, which have a high glass transition temperature, a lower viscosity, and excellent fiber impregnation properties, are suitable for filament winding (FILAMENT WINDING, FW) molding or drawing molding, and have excellent tensile elasticity and tensile strength, among urethane-modified epoxy resins used for casting materials, composite materials, structural adhesives, and the like.

[ Means of solving the problems ]

The present invention is a polyurethane modified epoxy resin composition comprising the following components (A) to (C):

(A) A polyurethane modified epoxy resin having a structure derived from a polyol and a structure derived from a polyisocyanate, wherein the structure having an isocyanate group at the terminal of a molecular chain is reacted with a hydroxyl group of an epoxy resin having an average of two or more epoxy groups in the molecule,

A structure comprising 55 mol% or more of a polycarbonate diol having a structural unit comprising a cyclic ether structure and a carbonate group in a molecule,

More than 1/3 of the number of moles of the epoxy resin having two or more epoxy groups in the molecule is aliphatic epoxy resin,

The concentration of the carbamate component is 15 to 60 weight percent;

(B) Polyurethane unmodified epoxy resin; and

(C) The hardening agent is used as a curing agent,

The composition contains 20 to 70 wt% of component (A), 30.0 to 80.0 wt% of component (B) and 0.1 to 20.0 wt% of component (C) relative to the whole composition.

The polyurethane-modified epoxy resin composition of the present invention is characterized in that, in the component (A), the polycarbonate diol forming a structure derived from the polycarbonate diol comprises a structure represented by the general formula (5).

( Here, R is a divalent group having 1 to 15 carbon atoms which contains a structure derived from a difunctional alcohol which may contain oxygen, and at least a part of the group contains a structure derived from a compound represented by the general formula (6); m is a number of 1 to 50. )

In addition, it is desirable that: in the polyurethane-modified epoxy resin (a), 1/2 or more of the number of moles of the epoxy resin having two or more epoxy groups in the molecule on average is an aliphatic epoxy resin.

In addition, it is preferable that: the weight average molecular weight of the polyurethane modified epoxy resin (A) is 3000 or more.

In addition, it is preferable that: in the polyurethane modified epoxy resin (a), the aliphatic epoxy resin is a polyglycidyl ether of trimethylolpropane.

The present invention also relates to a cured product obtained by curing the polyurethane-modified epoxy resin composition, a resin composition for a fiber-reinforced composite material obtained by impregnating reinforcing fibers with the composition, and a fiber-reinforced composite material obtained by the resin composition.

The present invention also provides a polyurethane-modified epoxy resin having a structure obtained by reacting a hydroxyl group of an epoxy resin having a structure derived from a polyol and a structure derived from a polyisocyanate and having an isocyanate group at a terminal of a molecular chain and having an average of two or more epoxy groups in a molecule,

The concentration of the urethane component is 15 to 60% by weight.

[ Effect of the invention ]

The polyurethane-modified epoxy resin composition of the present invention preferably has a viscosity of 50pa·s or less at 25 ℃ and a low viscosity, is excellent in fiber impregnation property, suppresses a decrease in glass transition temperature, and is excellent in tensile elasticity and tensile strength in a state where a cured product is optimally phase-separated, and therefore is suitable for a matrix resin or an adhesive formulation resin for composite materials for industrial use, sports and leisure use, civil engineering and construction use, etc. requiring mechanical properties or interfacial strength.

Detailed Description

The polyurethane modified epoxy resin composition of the present invention is characterized in that: the polyurethane-modified epoxy resin (a) contains, as essential components, a polyurethane-unmodified epoxy resin (B) and a hardener (C) as a regulator of the polyurethane concentration, and the polyurethane-modified epoxy resin (a), the polyurethane-unmodified epoxy resin (B) and the hardener (C) are contained in an amount of 20 to 70 wt% and 0.1 to 20.0 wt% based on the total amount (solid content) of the epoxy resin composition.

The resin composition of the present invention may optionally contain a hardening accelerator (D), an inorganic filler such as calcium carbonate, talc or titanium dioxide, or a release agent.

The polyurethane-modified epoxy resin (A) used in the present invention uses, as essential components, a liquid bisphenol-type epoxy resin (a-1) or an epoxy resin having two or more epoxy groups in the molecule on average (hereinafter, these may be collectively referred to as (a)), a polyol compound such as a polycarbonate diol (b-1) having a cyclic ether structure and a structural unit of a carbonate group in the molecule, and a polyisocyanate compound (c). In addition to the polycarbonate diol, a polyol compound (b-2) having a number average molecular weight of 500 or more and a low molecular weight polyol compound (d) having a number average molecular weight of less than 500 as a chain extender can be suitably used from the viewpoints of optimization of physical properties and viscosity, fine adjustment of compatibility, molecular weight control, and the like. The number average molecular weight described herein is a value converted from a hydroxyl value (hydroxyl value), and the hydroxyl value is usually measured by a measurement method based on japanese industrial standard (Japanese Industrial Standards, JIS) K1557. The following is the same.

The components of the polyurethane-modified epoxy resin (a) will be described below.

As the epoxy resin (a) having two or more epoxy groups on average in the molecule, the use of the above-mentioned (a-1) or (a-2) is preferable. It is preferable in terms of having two or more epoxy groups in the molecule on average, and exhibiting various physical properties in the reaction with the subsequent curing agent.

The epoxy resin (a-1) is a preferable component for exhibiting heat resistance and mechanical properties, and is preferably in a liquid state at ordinary temperature, and in this respect, it has an epoxy equivalent of 300g/eq or less. Further preferred are epoxy resins having an epoxy equivalent of 150g/eq to 300g/eq and a hydroxyl equivalent of 800g/eq to 3600 g/eq. Specifically, a bisphenol type epoxy resin containing a secondary hydroxyl group having an epoxy equivalent of 150g/eq to 200g/eq and a hydroxyl equivalent of 2000g/eq to 3000g/eq represented by the following general formula (1) is preferable.

Wherein R ₁ is each independently H or alkyl, and a is a number of 0 to 10. When R ₁ is an alkyl group, the carbon number is preferably in the range of 1 to 3, more preferably 1.

Particularly preferred epoxy resins (a-1) are bisphenol A type epoxy resins represented by the formula (1 a) and/or bisphenol F type epoxy resins represented by the formula (1 b).

Wherein a1 and a2 are numbers of 0 to 10.

In the formulas (1), (1 a) and (1 b), the average value (number average) of the repetition number a, the repetition number a1 or the repetition number a2 is in the range of 1 to 5, preferably in the range of 1 to 3.

The epoxy resin (a-2) is a preferable component for reducing the viscosity of the polyurethane-modified epoxy resin and the composition using the same, and the viscosity at 25 ℃ is preferably 100 mPas to 5000 mPas. The epoxy resin having a hydroxyl group in the structure may have either a primary hydroxyl group or a secondary hydroxyl group, and either of them may be used for the reaction, or the hydroxyl group of the epoxy resin whose terminal glycidation is not completed at all may be used. From the viewpoint of lowering the viscosity of the polyurethane-modified epoxy resin and the composition using the same, an aliphatic epoxy resin (a-2) having a total mole number of 1/3 or more of the epoxy resin (a) to be reacted with the epoxy resin (a) is used. Preferably, 1/2 or more of the total weight of the composition is used. More preferably 2/3 or more of the molar number. Further, the "number of moles" mentioned herein is preferably a value obtained by dividing the amount (mass) of each epoxy resin to be used by the hydroxyl equivalent to convert it into a unit of functional group. In the present invention, it is assumed that one of the secondary hydroxyl groups of the epoxy resin (a-1) and the polymer of the epoxy resin (a-2) (for example, in the case of a=1 or more of the above formula (1)) reacts with an isocyanate group to form a urethane prepolymer in the form of an end-capped urethane structure, but it is also assumed that the end of the urethane structure is not end-capped and tends to contribute to the extension of a molecular chain or the gelation due to the increase of a molecular weight when a=2 or more. Therefore, since a=1 bodies account for most of the contents except for a=0 bodies, a case is envisaged in which the value divided by the hydroxyl equivalent generally shows the number of n1 bodies. Therefore, this number is expressed as a mole number, and the ratio of numbers is expressed as a mole ratio.

The aliphatic epoxy resin is preferably polyglycidyl ether of an aliphatic alcohol having two or more members, and may have an alicyclic skeleton. Examples of the dibasic aliphatic alcohol include: 1, 4-butanediol, 3-methyl-1, 5-pentanediol, diethylene glycol, neopentyl glycol, 1, 6-hexanediol, 1, 9-nonanediol, cyclohexanedimethanol, propylene glycol, and the like. Further, as the aliphatic alcohol having three or more members, there may be mentioned: glycerol, trimethylol propane, trimethylol ethane, tetramethylol propane, sorbitol, pentaerythritol, and the like. Among them, polyglycidyl ethers of trimethylolpropane are preferable in terms of viscosity, compatibility, mechanical properties and the like.

The polycarbonate diol (b-1) is a polycarbonate diol having a structural unit containing a carbonate group represented by the following general formula (5), and has a structural unit derived from a dihydroxy (difunctional alcohol) compound having a cyclic ether structure represented by the following general formula (6). The structural unit derived from the dihydroxy (difunctional alcohol) compound may specifically be a structural unit derived from at least one selected from the group consisting of isosorbide, isomannide (isomannide) and isoidide (isoidite).

In the formula (5), R is a divalent group having 1 to 15 carbon atoms and originating from a structure of a dihydroxyl (difunctional alcohol) compound which may contain oxygen. At least a part of the structural units are derived from the compound represented by the general formula (6). m is a number of 1 to 50. The structure derived from a dihydroxy (difunctional alcohol) compound means a residual structure of the dihydroxy (difunctional alcohol) compound from which at least one hydroxyl group (may include a part) at the molecular terminal has been removed.

The polycarbonate diol may have a structural unit other than the structural unit derived from the dihydroxy (difunctional alcohol) compound having a cyclic ether structure represented by general formula (6) in a part of the structure, or may have a repeating structure of a divalent hydrocarbon group having 2 to 20 carbon atoms. Examples of the divalent hydrocarbon group having 2 to 20 carbon atoms include those derived from alkylene ether glycol. Specifically, the structure is derived from at least one selected from the group consisting of polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, a copolymerized polytetramethylene ether glycol of 3-methyltetrahydrofuran and tetrahydrofuran, a copolymerized polyether polyol of neopentyl glycol and tetrahydrofuran, a copolymerized polyether polyol of ethylene oxide and tetrahydrofuran, and a copolymerized polyether glycol of propylene oxide and tetrahydrofuran.

The compound having a divalent hydrocarbon group having 4 to 12 carbon atoms is a structural unit derived from at least one selected from the group consisting of neopentyl glycol, 3-methyl-1, 5-pentanediol, 2-methyl-1, 3-propanediol, and 2-methyl-1, 4-butanediol.

In a part of the structure of the polycarbonate diol, the dihydroxy compound having a cyclic ether structure represented by general formula (6) is 10 to 90 mol%, preferably 20 to 80 mol% in the form of a structural unit.

The polycarbonate diol (including the case where a part of the structure includes a structure derived from a dihydroxy compound having a cyclic ether structure represented by the general formula (6)) which can be obtained as a commercially available product includes Bei Niao mol (Benebiol) HS0840H (trade name, manufactured by mitsubishi chemical Co., ltd.) and the like.

The structure derived from the polycarbonate diol (b-1) in the component (A) is 55 mol% or more of the structures derived from all the polyol compounds including the polyol compound (b-2) described later. That is, when the structure derived from the polycarbonate diol (b-1) in (b-1) and (b-2) is used in such an amount within the range, the cured product can exhibit high elasticity and high strength, and thus is preferable. More preferably, 75 mol% or more, still more preferably 100 mol% or more can be used. The term "mol" as used herein means a value obtained by dividing the weight of each component by the number average molecular weight. However, the polyol compounds other than the polycarbonate diol (b-1) herein do not include the low molecular weight polyol compound (d) having a number average molecular weight of less than 500 as a chain extender, which will be described later.

The polyol compound (b-2) other than the polycarbonate diol (b-1) is a compound represented by the following formulas (2 b) to (2 d), and examples thereof include: polyethylene glycol (polyethylene glycol, PEG), polypropylene glycol (polypropylene glycol, PPG), polytetramethylene ether glycol (poly TETRAMETHYLENE ETHER glycol, PTMG), polyethylene propylene glycol (polyethylene propylene glycol, PEPG), copolymers of two or more alkylene oxides (e.g., ethylene oxide-propylene oxide copolymers), and the like. As the (b-2), a polyol compound such as a lactone-modified polyol, a polyester polyol, a polycarbonate polyol or the like may be used within a range that does not hinder the object of the present invention, and one or two or more of them may be used in combination. As for these (b-2) components, those having the same number average molecular weight as (b-1) are also preferable.

R ₂ is H or methyl, b1, b2, b3 are independently a number of 1 to 50, and c is a number of 0 or 1.

Here, q1, q2, q3, q4 are independently a number of 1 to 20.

Here, r, s, t are independently a number of 1 to 20, and n is a number of 1 to 50.

The number of NCO groups of the polyisocyanate compound (c) is not less than 2, but is preferably not less than 2. Preferably a compound represented by the general formula (3) and R ₄ is a divalent group selected from the group consisting of the formulae (i) to (vi). Among these, a compound excellent in compatibility with the epoxy resin (a) can be preferably selected.

Specifically, there may be mentioned: toluene diisocyanate (toluene diisocyanate, TDI), 4' -diphenylmethane diisocyanate (DIPHENYL METHANE diisocyanite, MDI), xylylene diisocyanate (xylylene diisocyanate, XDI), hydrogenated xylylene diisocyanate (hydrogenated xylylene diisocyanate, HXDI), isophorone diisocyanate (isophorone diisocyanate, IPDI), naphthalene diisocyanate, and the like.

OCN-R₄-NCO (3)

Here, R ₄ is preferably a divalent group selected from the formulae (i) to (vi).

In particular, 4' -diphenylmethane diisocyanate (MDI) represented by formula (3 a) is more preferable from the viewpoints of low molecular weight, no thickening, low cost, safety, and the like.

The low molecular weight polyol compound (d) is a polyol compound having a number average molecular weight of less than 500. Preferably less than 200. It is used as chain extender. The diol compound represented by the formula (4) and having two primary hydroxyl groups is preferable.

HO-R₅-OH (4)

R ₅ is an alkylene group represented by the formula (vii), and g is a number of 1 to 10.

The low molecular weight polyol compound (d) includes, for example, polyols such as 1, 4-butanediol and 1, 6-pentanediol. In particular, 1, 4-butanediol is more preferable in terms of easy availability and balance of price and characteristics.

Next, a description will be given of a reaction mechanism by using any or all of the components (a-1), (a-2), (b-1), (b-2), (c) and (d) exemplified above together with a polyurethane-modified epoxy resin. The components may be used singly or in combination.

The OH groups in the epoxy resin (a) (e.g., (a-1), (a-2)) are mainly secondary OH groups. On the other hand, the OH groups of the polycarbonate diol (b-1) and the polyol compound (b-2) other than the polycarbonate diol are mainly primary OH groups. Therefore, when the epoxy resin (a), the polycarbonate diol (b-1) and/or the polyol compound (b-2) other than the polycarbonate diol, the polyisocyanate compound (c) and the like are charged and reacted, the primary OH group of the (b-1) or (b-2) and the NCO group of the polyisocyanate compound (c) react preferentially.

Typically, it is considered that the primary OH groups in (b-1) and (b-2) react with the NCO groups in (c) first to form a urethane prepolymer (P1) having their NCO group ends bonded thereto. That is, the urethane prepolymer (P1) is a structure in which a structure derived from a polyol and a structure derived from a polyisocyanate compound are bonded to each other, wherein the structure is derived from (b-1) and (b-2). The structure derived from a polyol means a residual structure of a polyol compound from which at least one hydroxyl group (which may include a part) at the molecular end has been removed. The structure derived from the polyisocyanate compound means a residual structure of the polyisocyanate compound after at least one isocyanate group (may include a part) at the molecular end is removed. It is preferably produced as a urethane prepolymer (P1) having NCO groups at both terminals after the reaction. Thereafter, the OH group (preferably, a secondary OH group) in the epoxy resin (a) reacts with the terminal NCO group of the urethane prepolymer (P1) to form a urethane bond, and the urethane prepolymer (P2) is formed by adding the epoxy resin (a) to both ends or one end of the urethane prepolymer (P1).

That is, the urethane prepolymer (P) is considered to be a mixture of an NCO group-terminated urethane prepolymer (P1) and a urethane prepolymer (P2) having an epoxy resin (a) [ structure derived from the epoxy resin (a) ] added to both ends or one end of P1, but since the molar ratio of NCO groups is large, and the epoxy resin is excessively used in addition, it is considered that the urethane prepolymer (P2) having an epoxy resin added to both ends of P1 is mainly produced. The structure derived from the epoxy resin means a residual structure after removing at least one hydroxyl group (which may include a part) in the epoxy resin.

The epoxy resin (a) is preferably incorporated in an amount of 50 to 90% by weight based on the total amount of the components (a), (b-1), (b-2), (c) and (d). As the loading ratio of the epoxy resin (a) increases, both ends or one end of the urethane prepolymer (P1) are sealed with the epoxy resin (a), terminal NCO groups are consumed, the amount of the urethane prepolymer (P2) which does not react with the low molecular weight polyol compound (d) as a chain extender also increases, the proportion of the initial urethane prepolymer (P1) which is terminal NCO groups decreases, and the amount of the produced polyurethane by the reaction of the terminal NCO groups of P1 with the OH groups of the low molecular weight polyol compound (d) as a chain extender decreases, so that the molecular weight distribution of the polyurethane-modified epoxy resin also shifts to the low molecular weight side.

Conversely, when the loading ratio of the epoxy resin (a) is reduced, the amount of the urethane prepolymer (P2) having both ends or one end sealed with the epoxy resin (a) is reduced, and the ratio of the initial urethane prepolymer (P1) having the terminal NCO group maintained therein is increased. Therefore, the amount of polyurethane formed by the reaction of the terminal NCO groups of P1 with the OH groups of the low molecular weight polyol compound (d) as a chain extender increases, and thus the molecular weight distribution of the polyurethane-modified epoxy resin also shifts to the high molecular weight side.

The epoxy resin (a) is, for example, a mixture of a single-unit compound having a repetition number a of 0 and a polymer having a repetition number a of 1 or more, and the polymer has a secondary OH group formed by ring-opening of an epoxy group. The secondary OH group is reactive with the NCO group of the polyisocyanate compound (c) or the NCO group at the end of the urethane prepolymer (P), and thus, when the epoxy resin (a-1) or the epoxy resin (a-2) has a secondary OH group (for example, a=1 or more of the formula (1)). In addition, in the case where the epoxy resin (a) does not have a secondary OH group (for example, a=0 body in the formula (1), etc.), the reaction is not involved. As described above, the polyurethane-modified epoxy resin (a) in the present invention is understood to have a complex structure in which any or all of the above-described components (a-1), (a-2), (b-1), (b-2), (c) and (d) are reacted, and is in the form of a mixture containing the above-described epoxy resin (a) having no OH group in a state that is considered not directly involved in the reaction or the expression of the function but is difficult to be completely distinguished or excluded, and therefore, there are some cases where the component (a) cannot be directly determined by the structure or the characteristics thereof, or is substantially not practical (so-called impossible/not practical cases).

The polyurethane modified epoxy resin composition of the present invention exhibits high elasticity and high strength because the polyurethane modified epoxy resin portion undergoes phase separation in the epoxy resin composition.

Since the island portions after phase separation are incompatible with the sea portion, the polyurethane-modified epoxy resin (a) preferably has a weight average molecular weight of 3000 or more, and the amount of the urethane component (a), that is, the blending amount of the polyol compound and the polyisocyanate compound, described later, is preferably 6% by weight or more relative to the total amount of the entire composition. The weight average molecular weight is more preferably 3500 or more, and still more preferably 5000 or more. In addition, 15000 or less may be used. In order to form a desired phase separation structure, the amount of the urethane component (a), that is, the blending amount of the polyol compound and the polyisocyanate compound, to be described later in the component (a) may be 6.0% by weight or more and 15% by weight or less, and more preferably 8.0% by weight or more and 12% by weight or less, relative to the total amount of the entire composition.

As a method for producing the polyurethane-modified epoxy resin (A) used in the present invention, for example, the method comprises reacting (1) a (a-1) and (a-2) as an epoxy resin (a) in an amount of 50 to 90% by weight based on the total amount of the polycarbonate diol (b-1) as a polyether polyol compound, the polyol compound (b-2) other than the polycarbonate diol, the polyisocyanate compound (c) and the low molecular weight polyol compound (d) having a number average molecular weight of less than 500 as a chain extender, and reacting (b-1), (b-2) and the polyisocyanate compound (c) in the presence of the epoxy resin (a). In the above reaction 1, the reaction of (b-1), (b-2) with the polyisocyanate compound (c) preferentially occurs to produce the urethane prepolymer (P1). Thereafter, the urethane prepolymer (P1) and the epoxy resin (a) are reacted to mainly produce a urethane prepolymer (P2) having both ends of P1 epoxidized.

The reaction of the urethane prepolymer (P1) with the epoxy resin (a) requires that the OH groups (mainly, low-reactivity secondary OH groups) in the epoxy resin (a) react with the NCO groups of P1 to form urethane bonds, and thus the reaction temperature is preferably in the range of 80 to 150 ℃, and the reaction time is preferably in the range of 1 to 5 hours.

Thereafter, the molar ratio (P1) of NCO groups in the urethane prepolymer (P1) to OH groups in the low molecular weight polyol compound (d) is optionally: (d) becomes 0.9:1.0 to 1.0: the low molecular weight polyol compound (d) was added in a range of 0.9 to carry out the polyurethane reaction (reaction 2). Further, the epoxy group of the epoxy resin and the OH group of the polyol compound (d) are alcoholic OH groups, and thus do not react.

The reaction temperature of the reaction 2 is preferably in the range of 80℃to 150℃and the reaction time is preferably in the range of 1 hour to 5 hours, but the reaction between the NCO groups and the OH groups in the low molecular weight polyol compound (d) is preferably under milder conditions than the reaction 1.

In the course of the reactions (reactions 1 and 2), a catalyst may be used as necessary. The catalyst is used for the purpose of sufficiently completing the formation of urethane bonds, and examples thereof include amine compounds such as ethylenediamine, tin compounds, and zinc compounds.

In reaction 2, the remaining urethane prepolymer (P1) having NCO at both ends or one end is reacted with the low molecular weight polyol compound (d), the chain length is extended and polyurethane is formed, and the urethane prepolymer (P2) having an adduct of epoxy resin (a) at both ends is left unreacted with the component (d).

When the low molecular weight polyol compound (d) is not used, the terminal NCO reacts with each hydroxyl group to form the urethane prepolymer (P2) when the polyisocyanate compound (c) is added.

The polyurethane-modified epoxy resin used in the present invention preferably has an epoxy equivalent of 180g/eq to 1000g/eq and a viscosity of 0.1 Pa.s to 30 Pa.s at 120 ℃.

By increasing or decreasing the blending amount of the polyurethane-unmodified epoxy resin (B), the polyurethane concentration in the polyurethane-modified epoxy resin composition can be increased or decreased. Here, if the above-exemplified components are used, the polyurethane concentration in the epoxy resin composition is calculated by the following equation, but the kind of each component is not limited thereto.

Polyurethane concentration = { (B-1) + (B-2) + (C) + (d) } ×100/{ (a) + (B) + (C) }

In this case, (a) = (a-1) + (a-2) + (b-1) + (b-2) + (c) + (d).

Here, (a-1), (a-2), (B-1), (B-2), (C), (d), (A), (B) and (C) are the weights of the respective components used. In addition, when other components, for example, the hardening accelerator (D) and the like are blended, these other components are added to the denominator.

In the present invention, the concentration of the polyurethane in the epoxy resin composition is preferably 5 to 30% by weight, more preferably 6 to 20% by weight.

In the polyurethane-modified epoxy resin (A) of the present invention, in the above-exemplified cases, the urethane component concentration means { (b-1) + (b-2) + (c) + (d) }/{ (a-1) + (a-2) + (b-1) + (b-2) + (c) + (d) }. In the present invention, the urethane component concentration is 15 to 60 wt%, and may preferably be 18 to 45 wt%. If the urethane component concentration is less than 15 wt%, the molecular weight of the urethane is reduced, the island compatibility during phase separation is increased, and it is difficult to form a sufficient island size, and the necessary physical properties may not be exhibited, whereas if it exceeds 60 wt%, the molecular weight of the urethane is increased to be more than necessary, and the viscosity of the polyurethane-modified epoxy resin and the composition thereof is increased, and thus there is a concern that the impregnation property into carbon fibers or the like is reduced.

As the polyurethane unmodified epoxy resin (B) used in the polyurethane modified epoxy resin composition of the present invention, (a-1), (a-2) and the like of the epoxy resin (a) used as a raw material of the polyurethane modified epoxy resin (a) can be preferably used. That is, an epoxy resin which is liquid at 30 ℃ without polyurethane modification is preferable. Among them, bisphenol a type epoxy resins and/or bisphenol F type epoxy resins are preferable in terms of easy availability, and balance of price and characteristics. As (a-2), polyglycidyl ethers of trimethylolpropane are preferable from the viewpoints of viscosity, compatibility, mechanical properties and the like.

In the polyurethane-modified epoxy resin composition of the present invention, as the polyurethane-unmodified epoxy resin (B), a trifunctional or higher-functional epoxy resin may be used for the purpose of adjusting viscosity or increasing Tg. When a multifunctional epoxy resin is used, the crosslinking density increases, and the phase separation state changes or the fracture toughness is lost, so that the content is preferably 0.1 to 10% by weight based on the total weight of the composition. Examples of the trifunctional or higher-functional epoxy resin include: phenol novolac type epoxy resins, cresol novolac type epoxy resins, glycidyl amine type epoxy resins such as tetraglycidyl diaminodiphenylmethane, glycidyl phenyl ether type epoxy resins such as tetra (glycidyl oxyphenyl) ethane or tris (glycidyl oxyphenyl) methane, glycidyl amine type and glycidyl phenyl ether type epoxy resins such as triglycidylaminophenol. Examples of the epoxy resin include an epoxy resin obtained by modifying such an epoxy resin, and a brominated epoxy resin obtained by brominating such an epoxy resin.

In this case, it is preferable to use an epoxy resin having a viscosity of 10000 mPas or less at 25 ℃. As a result, the composition has a reduced viscosity and improved impregnation into carbon fibers, and can be applied to a tow prepreg (tow pre) and drawing. Examples include: glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, alicyclic epoxy resins, and the like. These epoxy resins may be used alone or in combination of two or more.

Examples of the glycidyl ether type epoxy resin include: a glycidyl ether type epoxy resin, a butyl glycidyl ether type epoxy resin, a phenyl glycidyl ether type epoxy resin, a (poly) ethylene glycol diglycidyl ether type epoxy resin, a (poly) propylene glycol diglycidyl ether type epoxy resin, a neopentyl glycol diglycidyl ether type epoxy resin, a1, 4-butanediol diglycidyl ether type epoxy resin, a1, 6-hexanediol diglycidyl ether type epoxy resin, a trimethylolpropane polyglycidyl ether type epoxy resin, a diglycidyl polyglycidyl ether type epoxy resin, an allyl glycidyl ether type epoxy resin, a 2-ethylhexyl glycidyl ether type epoxy resin, a p- (tert-butyl) phenyl glycidyl ether type epoxy resin, a dodecyl glycidyl ether type epoxy resin, a tridecyl glycidyl ether type epoxy resin, and the like. These glycidyl ether type epoxy resins may be used alone or in combination of two or more.

Examples of the glycidyl ester type epoxy resin include: hexahydrophthalic anhydride diglycidyl ester type epoxy resin, tetrahydrophthalic anhydride diglycidyl ester type epoxy resin, tertiary fatty acid monoglycidyl ester type epoxy resin, phthalic acid diglycidyl ester type epoxy resin, dimer acid glycidyl ester type epoxy resin, and the like. These glycidyl ester type epoxy resins may be used alone or in combination of two or more.

Examples of the glycidylamine-type epoxy resin include: meta- (glycidoxyphenyl) diglycidyl amine type epoxy resins, N-diglycidyl aminobenzene type epoxy resins, ortho- (N, N-diglycidyl amino) toluene type epoxy resins, and the like. These glycidylamine-type epoxy resins may be used alone or in combination of two or more.

Examples of the alicyclic epoxy resin include: alicyclic diepoxy adipate type epoxy resin, 3, 4-epoxycyclohexylmethyl carboxylate type epoxy resin, vinylcyclohexene dioxide type epoxy resin, hydrogenated bisphenol A diglycidyl ether type epoxy resin, and the like.

As the hardener (C), dicyandiamide (DICYANDIAMIDE, dic) or a derivative thereof can be used in terms of achieving a liquefaction excellent in storage stability and being easily obtainable. Examples of the derivative include: guanidine, guanylurea (DICYANDIAMIDINE), biguanidine (diguanide), melamine, and the like.

In the case where the curing agent is DICY, the blending amount of the curing agent (C) is preferably from the viewpoint of the cured product characteristics: the ratio of the number of moles of epoxy groups of the total epoxy resins including the polyurethane modified epoxy resin (a) and the polyurethane unmodified epoxy resin (B) to the number of moles of active hydrogen groups of dic was set to 1:0.3 to 1:1.2, preferably 1:0.9 to 1:1.1.

In the polyurethane-modified epoxy resin composition of the present invention, the component (a) may be 20 to 70% by weight. The component (B) may be 30.0 to 80.0 wt%. The component (C) may be contained in an amount of 0.1 to 20.0 wt%, and preferably 1 to 10 wt%.

The polyurethane-modified epoxy resin composition of the present invention may further contain a hardening accelerator (D). The hardening accelerator (D) is preferably used for suppressing an increase in impregnation into the reinforcing fiber and viscosity when the imidazole-based hardening aid is mixed, and is also preferably used for satisfying heat resistance at the time of hardening. As the imidazole-based curing assistant, 2-methylimidazole, 1, 2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4 ',5' -dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and the like are preferably used. Further, an imidazole compound containing a triazine ring is preferable, and examples of such a compound include: 2, 4-diamino-6- [2' -methylimidazolyl- (1 ') ] -ethyl-s-triazine, 2, 4-diamino-6- [2' -ethyl-4 ' -methylimidazolyl- (1 ') ] -ethyl-s-triazine, 2, 4-diamino-6- [2' -undecylimidazolyl- (1 ') ] -ethyl-s-triazine, and the like. Among them, 2, 4-diamino-6- [2 '-methylimidazolyl- (1') ] -ethyl-s-triazine may be more preferably used from the viewpoint of being curable in a short time. The triazine ring-containing imidazole compounds may be used either alone or in combination of two or more.

On the other hand, depending on the application and the method, hardening in a short time as described above may not be required. In this case, crystalline imidazole compounds such as 2, 4-diamino-6- [2 '-methylimidazolyl- (1') ] -ethyl-s-triazine isocyanurate addition salt (2 MA-OK) and urea compounds such as 3- (3, 4-dichlorophenyl) -1,1-dimethylurea (3- (3, 4-dichlorophenyl) -1,1-dimethylurea, DCMU) can be used. The amount of the hardening accelerator (D) is preferably in the range of 0.1 to 5wt% based on the total of the entire epoxy resin including the polyurethane modified epoxy resin (a) and the polyurethane unmodified epoxy resin (B) and the hardening agent (C).

The epoxy resin composition of the present invention may optionally contain a release agent (E) according to the use or the working method. The release agent may be a liquid release agent, a solid (powder) release agent, or the like, and may be a liquid release agent at ordinary temperature (10 to 30 ℃) so that even in a low-viscosity composition, the release agent can be uniformly mixed. In addition, by mixing a release agent into the resin, the drawing formability is improved. This improves the orientation of the fibers in the molded article, and therefore, the mechanical properties such as compression strength of the molded article are increased, and the adhesion to the adhesive is increased due to the smooth surface.

The amount of the release agent to be blended is preferably 0.1 to 6 parts by mass based on 100 parts by mass of the entire epoxy resin. More preferably 0.1 to 4 parts by mass. If the amount is less than 0.1 part by mass, sufficient releasability may not be obtained. If the amount exceeds 6 parts by mass, the strength of the molded article may be lowered, or the adhesion or adhesiveness may be lowered. The release agents may be used singly or in combination of two or more kinds.

The liquid release agent is not particularly limited as long as it does not phase separate from the epoxy resin composition and does not evaporate or decompose at the temperature of the mold. Specific commercial products include: mordevitalite (MOLDWIZ INT) -1324, 1324B, 1836, 1846, 1850, 1854, 1882, etc. manufactured by Baindustrial Co., ltd.

Examples of the solid (powder) mold release agent include shellac wax (shellac wax) as an animal wax, beeswax, spermaceti wax, carnauba wax (carnauba wax) as a plant wax, paraffin wax (haze wax) as a mineral wax, microcrystalline wax (microcrystalline wax), and fischer-tropsch wax (fischer-tropsch wax) as a synthetic wax, polyethylene wax, polypropylene wax, and the like, and it is desirable that the resin composition be in a powder form that can be uniformly dispersed in an epoxy resin composition, and that the resin composition be in a melted and dissolved state at a temperature at the time of molding and hardening.

The epoxy resin composition of the present invention may optionally contain a rubber component (F) depending on the use or the method. The copolymer containing acrylonitrile and butadiene as raw materials is preferably used because of its excellent solubility in the epoxy resin, but since the viscosity of the resin composition is easily increased, it is preferably particles containing a rubber component insoluble in the epoxy resin. The crosslinked rubber particles themselves may be used, and particularly preferably have a core-shell structure in which the surface of the rubber particles insoluble in the epoxy resin is coated with a non-rubber component. In this case, the component to be coated may be a component that dissolves or swells in the epoxy resin, such as polymethyl methacrylate, but rather the dispersion of the particles in the epoxy resin becomes good, so that it is preferable.

The average particle diameter of the rubber component is preferably 1nm to 500nm, more preferably 3nm to 300nm, in terms of volume average particle diameter. The blending amount of the rubber component (F) is preferably 1 to 15% by weight, more preferably 3 to 12% by weight, based on the total weight of the composition. By adding the rubber component, the fracture toughness required for the fiber reinforced composite material after molding is easily obtained.

The cured product of the present invention is obtained by curing the epoxy resin composition. The method for obtaining the cured product may be a curing method based on a general curable resin composition, and for example, the heating temperature condition may be appropriately selected according to the type, use, and the like of the curing agent to be combined. For example, a method of heating the epoxy resin composition at a temperature ranging from room temperature to about 250 ℃. General methods of the curable resin composition can also be used, such as molding methods.

Since the cured product of the present invention has excellent heat resistance, excellent tensile elasticity and excellent tensile strength, the glass transition temperature (Tg) of the cured product is preferably 105 ℃ or higher, the tensile elastic modulus is preferably 3.2GPa or higher, and the tensile strength is preferably 80MPa or higher.

The fiber-reinforced composite material of the present invention can be obtained by impregnating reinforcing fibers with the epoxy resin composition of the present invention to obtain a composition for a fiber-reinforced composite material and curing the composition by molding. Here, the reinforcing fiber may be any of twisted yarn, untwisted yarn, and the like, but untwisted yarn or untwisted yarn is preferable because it has excellent moldability in the fiber-reinforced composite material. Further, as the form of the reinforcing fiber, a form in which the fiber direction is aligned in one direction or a fabric may be used. The fabric may be freely selected from plain weave fabrics, satin weave fabrics, and the like according to the site of use or use. Specifically, carbon fibers, glass fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers, and the like may be used alone or in combination of two or more of them, for example, for excellent mechanical strength and durability. Among these, carbon fibers are preferable in terms of the strength of molded articles, and various carbon fibers such as polyacrylonitrile-based carbon fibers, pitch-based carbon fibers, and rayon-based carbon fibers can be used.

The method for obtaining the fiber-reinforced composite from the epoxy resin composition of the present invention is not particularly limited, and examples thereof include the following methods: a method of producing a varnish by uniformly mixing the components constituting the epoxy resin composition, wherein the varnish obtained in the above step is impregnated with unidirectional reinforcing fibers in which reinforcing fibers are aligned in one direction (a state before curing in a pultrusion method or a filament winding method, a strand prepreg), and a method of producing a varnish by impregnating a resin in a substrate such as a material in which continuous carbon fibers are arranged in one direction and formed into a sheet shape or a carbon fiber woven fabric, a material in which a resin layer is disposed on at least one surface of a carbon fiber substrate, and a material in which a fiber layer is further disposed on the surface; and a method (RESIN TRANSFER molding, RTM) in which a sheet or a fabric of reinforcing fibers is placed in a mold in a superimposed manner, and then resin is injected into the mold and pressure is applied to impregnate the sheet or the fabric or the inside is depressurized to impregnate the sheet or the fabric.

In the fiber-reinforced composite material of the present invention, the volume content of the reinforcing fibers is preferably 40 to 85% based on the total volume of the molded article, and more preferably 50 to 75% in terms of strength. When the volume content is less than 40%, the content of the epoxy resin composition may be too large, and the elastic modulus or strength of the cured product obtained may be insufficient or may not satisfy various properties required. If the volume content exceeds 85%, the resin in the reinforcing fiber is insufficient, resulting in insufficient adhesion, void generation, or the like, and the cured product may have insufficient elastic modulus or strength, or reduced interfacial adhesion.

Examples (example)

Next, the present invention will be specifically described based on examples. The present invention is not limited to the specific examples described above, and any modifications and alterations can be made without departing from the gist of the present invention.

The evaluation methods of the physical properties are as follows.

(1) Determination of the presence or absence of residual NCO groups by means of infrared radiation (INFRARED RAY, IR): after 0.05g of the obtained polyurethane-modified epoxy resin was dissolved in 10ml of tetrahydrofuran, the solution was applied to KBr plate using a micro-spatula plate portion, and dried at room temperature for 15 minutes to evaporate the tetrahydrofuran, thereby preparing a sample for IR measurement. This was set on a Fourier transform infrared spectrum (Fourier transform infrared spectrum, FT-IR) device spectrum-1 (spectrum-one) manufactured by Perkin Elmer (PERKIN ELMER), and when the stretching vibration absorption spectrum of 2270cm ^-1, which is a characteristic absorption band of NCO groups, disappeared, it was determined that there was no residual NCO groups.

(2) Epoxy equivalent: quantification was performed according to JISK 7236.

(3) Hydroxyl equivalent: 25ml of dimethylformamide was taken out in a 200ml Erlenmeyer flask with a glass stopper, and a sample containing 11 mg/equivalent or less of hydroxyl group was precisely weighed and added thereto to dissolve the same. 20ml of 1 mol/L-phenylisocyanate toluene solution and 1ml of dibutyltin maleate catalyst solution are added by a pipette respectively, and the mixture is fully stirred and mixed by shaking and tightly covered, so that the mixture is reacted for 30 to 60 minutes. After the completion of the reaction, 20ml of a2 mol/L-dibutylamine toluene solution was added and mixed by stirring with sufficient shaking, and the mixture was left for 15 minutes to react with an excessive amount of phenyl isocyanate. Next, 30ml of methyl cellosolve and 0.5ml of bromocresol green indicator were added, and the excess amine was titrated with a calibrated methyl cellosolve solution. Since the indicator changes from blue to green and then to yellow, the initial point of the change to yellow is set as the end point, and the hydroxyl equivalent is determined using the following formulas i and ii.

Hydroxyl equivalent weight (g/eq) = (1000×w)/C (S-B) … (i)

C: concentration (mol/L) of methyl Cellosolve perchlorate solution

W: sample amount (g)

S: titration amount (ml) of methyl cellosolve perchlorate solution

B: titration amount (ml) of methyl cellosolve perchlorate solution required for blank test at the time of titration

C＝(1000×W)/{121×(s-b)}…(ii)

W: the amount of tris- (hydroxymethyl) -aminomethane taken (g) for calibration

S: titration amount (ml) of methyl cellosolve perchlorate solution required for titration of tris- (hydroxymethyl) -aminomethane

B: titration amount (ml) of methyl cellosolve perchlorate solution required for blank test at the time of calibration

(4) Hydroxyl number: the measurement was performed by the measurement method referring to JISK 1557.

(5) Viscosity: the viscosity values at 25℃were measured using an E-type viscometer cone plate type. The epoxy resin composition of the present invention was prepared, and 0.8mL thereof was used for measurement, and the value after 60 seconds from the start of measurement was taken as the viscosity value.

(6) Glass transition temperature (Tg): the intersection of the baseline and the tangent at the inflection point was derived as the glass transition temperature (Tg) using a differential scanning calorimeter (DIFFERENTIAL SCANNING calorimeter, DSC) at a heating rate of 10 ℃/min.

(7) Tensile test: the cured product molded into the shape of JIS K7161 by die casting was used as a test piece, and tensile test was performed at room temperature of 23℃using a universal tester, and the tensile strength, tensile elongation, and tensile elastic modulus were measured, respectively.

(8) Weight average molecular weight (Mw): the measurement was performed by gel permeation chromatography (gel permeation chromatography, GPC) under the following conditions.

Measurement device: HLC-8420GPC manufactured by Tosoh Co., ltd

And (3) pipe column: TSKgel SuperMultipore HZ-Mx2

Measurement conditions: temperature 40 ℃, eluent Tetrahydrofuran (THF), flow rate 0.35mL/min

Sample: polystyrene SRM706a

(9) Fracture toughness: the cured product molded into the shape of JIS K6911 by casting with a mold was used as a test piece, and the test was performed at a crosshead speed of 0.5mm/min at room temperature of 23℃using a universal tester. The incision (score) in the test piece before the test was made by bringing the blade of the razor into contact with the test piece and applying an impact to the blade of the razor with a hammer.

The raw materials used are as follows.

Component A

Epoxy resin (a-1):

Ebolter (Epotohto) YDF-170, bisphenol F type epoxy resin, epoxy equivalent 170g/eq, hydroxyl equivalent 2600g/eq, liquid, manufactured by Nippon STEEL CHEMICAL & Material

Epoxy resin (a-2):

Ebolter (Epotohto) YH-300 manufactured by Nippon STEEL CHEMICAL & Material, polyglycidyl ether of trimethylolpropane, epoxy equivalent 142g/eq, hydroxyl equivalent 837g/eq, liquid

Polycarbonate diol (b-1):

Bei Niao mol (Benebiol) HS0840H, number average molecular weight 800, hydroxyl equivalent 400g/eq, manufactured by Mitsubishi chemical corporation

Polyol compound (b-2):

Ai Dike polyether (Adeka Polyether) P-2000, polypropylene glycol, number average molecular weight 2000, hydroxyl equivalent weight 1000g/eq manufactured by Ai Dike (ADEKA)

Polyisocyanate compound (c):

Coosamonate PH, 4' -diphenylmethane diisocyanate (MDI) manufactured by Mitsui chemistry

Component B

Ebolter (Epotohto) YD-128, bisphenol A type epoxy resin, epoxy equivalent 187g/eq, liquid, manufactured by Nippon STEEL CHEMICAL & Material

Ebolter (Epotohto) YDF-170, bisphenol F type epoxy resin, epoxy equivalent 170g/eq, liquid, manufactured by Nippon STEEL CHEMICAL & Material

Ebolter (Epotohto) YH-300 manufactured by Nippon STEEL CHEMICAL & Material, polyglycidyl ether of trimethylolpropane, epoxy equivalent 142g/eq, liquid

Component C:

gemcinolone Ai Kusi (DICYANEX) 1400F, dicyandiamide manufactured by Yingji (EVONIK)

Component D:

crystalline imidazole, solid azole (Curezol) 2MZA-PW, 2, 4-diamino-6- [2 '-methylimidazolyl- (1') ] -ethyl-s-triazine manufactured by four-national chemical industry

Component F:

MX-154 manufactured by Kaneka Co., ltd., core-shell rubber 40wt%, bisphenol A (Bisphanol A, BPA) epoxy resin 60wt%, and average particle diameter of 150nm to 200nm

Example 1

Ebolter (Epotohto) YDF-170 was used as the epoxy resin (a-1), ebolter (Epotohto) YH-300 was used as the epoxy resin (a-2), mitsubishi chemical HS0840H was used as the polycarbonate diol, and Cosmonate PH (MDI) was used as the polyisocyanate (c). The amounts (unit: parts by weight) of these used are shown in Table 1.

A1000 ml four-port separable flask including a nitrogen inlet pipe, a stirrer and a temperature regulator was charged with Ebolter (Epotohto) YDF-170, ebolter (Epotohto) YH-300 and HS0840H, heated to 120℃and stirred and mixed for 120 minutes. Next, cosmonate (Cosmonate) PH was added and reacted at 120 ℃ for 2 hours to obtain a polyurethane modified epoxy resin (UE 1).

The completion of the reaction was confirmed by disappearance of the absorption spectrum of NCO groups by IR measurement. The obtained polyurethane-modified epoxy resin had an epoxy equivalent of 195g/eq and a weight average molecular weight of 5800.

Examples 2 to 5 and comparative examples 1 to 5

The reaction was carried out in the same manner as in example 1 except that the charged compositions of the raw materials were as shown in table 1, to obtain polyurethane-modified epoxy resins (UE 2 to UE 10). Regarding the epoxy equivalent, UE 2 is 222g/eq, UE 3 is 213g/eq, UE 4 is 179g/eq, UE 5 is 202g/eq, UE 6 is 215g/eq, UE 7 is 209g/eq, UE 8 is 242g/eq, UE 9 is 253g/eq, and UE 10 is 206g/eq.

Next, examples of the epoxy resin compositions and cured epoxy resin products using the polyurethane-modified epoxy resins obtained in examples 1 to 5 and comparative examples 1 to 5 are shown. The results are summarized in Table 2.

Example 6

The polyurethane-modified epoxy resin UE 1 obtained in example 1 as the polyurethane-modified epoxy resin (A), ebolter (Epotohto) YD-128 as the polyurethane-unmodified epoxy resin (B), ebolter (Epotohto) YDF-170, ebolter (Epotohto) YH-300, dicyandiamide as the hardener (C), and 2MZA-PW as the hardening accelerator (D) were each placed in a 200ml dedicated disposable cup (disposable cup) in the formulation described in Table 2, and vacuum defoamation was performed for 5 minutes using a vacuum planetary mixer in a rotation-revolution laboratory while stirring and mixing to obtain a liquid resin composition. Here, the molar ratio of epoxy groups to dicyandiamide is set to 1.0:0.5, 140g of a polyurethane-modified epoxy resin composition was prepared.

Next, the liquid resin composition was cast into a mold having a groove shape of the test piece size of JISK 7161. The test piece for tensile test was used by pouring a solution into a mold or a frame made of silicon having a dumbbell-type test piece size of 100mmL×10mmW×4mmt and a dynamic analysis (DYNAMIC MECHANICAL ANALYSIS, DMA) test piece size of 100mmL×10mmW×2mmt, and cutting the test piece into a size suitable for measurement. The casting property at this time is a level at which sufficient casting can be performed with a margin. Next, the resin composition was poured into a mold heated at 130 ℃ in advance, and then placed into a hot air oven, and heat-cured at 130 ℃ for 10 minutes to prepare an epoxy resin cured product test piece. The test results using the test pieces are shown in table 2.

Examples 7 to 16 and comparative examples 6 to 11

The reaction was carried out in the same manner as in example 1 except that the amounts of the raw materials were as shown in Table 2, to obtain a resin composition and a cured product. The test results using these test pieces are shown in table 2.

By using the polyurethane-modified epoxy resin composition of the present invention, curing is completed under such a short curing condition as 130℃for 10 minutes, and a resin composition having low viscosity and excellent impregnation properties, showing sufficient heat resistance, and simultaneously having excellent tensile elasticity and tensile strength can be obtained.

TABLE 1

[ Industrial applicability ]

The polyurethane-modified epoxy resin composition of the present invention has low viscosity, excellent fiber impregnation, suppressed glass transition temperature reduction, and excellent tensile elastic modulus, and therefore is useful for matrix resins for composite materials for industrial use, sports and leisure use, civil engineering and construction use, and blended resins for adhesives, and the like.

Claims

1. A polyurethane modified epoxy resin composition characterized by comprising the following components (A) to (C):

The concentration of the carbamate component is 15 to 60 weight percent;

(B) Polyurethane unmodified epoxy resin; and

(C) The hardening agent is used as a curing agent,

2. The polyurethane-modified epoxy resin composition according to claim 1, wherein in the polyurethane-modified epoxy resin (A), the polycarbonate diol forming the structure derived from the polycarbonate diol comprises the structure represented by the general formula (5),

Here, R is a divalent group having 1 to 15 carbon atoms which contains a structure derived from a difunctional alcohol which may contain oxygen, and at least a part of the group contains a structure derived from a compound represented by the general formula (6); m is a number of 1 to 50,

3. The polyurethane-modified epoxy resin composition according to claim 1, wherein in the polyurethane-modified epoxy resin (a), 1/2 or more of the moles of the epoxy resin having two or more epoxy groups in the molecule on average is an aliphatic epoxy resin.

4. The polyurethane-modified epoxy resin composition according to claim 1, wherein the weight average molecular weight of the polyurethane-modified epoxy resin (a) is 3000 or more.

5. The polyurethane-modified epoxy resin composition according to claim 1, wherein in the polyurethane-modified epoxy resin (a), the aliphatic epoxy resin is a polyglycidyl ether of trimethylolpropane.

6. A cured product obtained by curing the polyurethane-modified epoxy resin composition according to any one of claims 1 to 5.

7. A resin composition for fiber-reinforced composite materials, which is obtained by impregnating the reinforcing fibers with the polyurethane-modified epoxy resin composition according to any one of claims 1 to 5.

8. A fiber-reinforced composite material obtained from the resin composition for a fiber-reinforced composite material according to claim 7.

9. A polyurethane modified epoxy resin having a structure derived from a polyol and a structure derived from a polyisocyanate and having an isocyanate group at a terminal of a molecular chain, and a structure obtained by reacting a hydroxyl group of an epoxy resin having an average of two or more epoxy groups in a molecule,

The concentration of the urethane component is 15 to 60% by weight.