JP2024007372A - Polyurethane-modified epoxy resin, polyurethane-modified epoxy resin composition, and cured product using the composition, resin composition for fiber-reinforced composite material and fiber-reinforced composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composition using a new polyurethane-modified epoxy resin which has a high glass transition temperature, has low viscosity and excellent fiber impregnation property, and has high attenuation property in itself, as an urethane-modified epoxy resin used in a casting material, a composite material and a structural adhesive, and a cured product of the same.

SOLUTION: There are provided a polyurethane-modified epoxy resin composition which contains a polyurethane-unmodified epoxy resin (A), a polyurethane-modified epoxy resin (B) having such a structure that a structure having a polyether polyol-derived structure and a polyisocyanate-derived structure and having an isocyanate group at a 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, and a curing agent (C), as essential components, wherein 20-70 wt.% of the polyurethane-modified epoxy resin (B) is contained with respect to the total amount (solid content) of the epoxy resin composition, the component (A) and the component (B) are compatible with each other, as the cured product after curing reaction, the component (A) and the component (B) form a phase-separation structure, a loss coefficient (tanδ) measured using a dynamic viscoelasticity apparatus under the conditions of a frequency of 10 Hz and temperature rise speed of 2°C/min is 0.03 or more in a temperature range of -40°C to 40°C, and viscosity at 25°C measured by an E type viscometer is 50 Pa s or less; and a cured product using the same.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an epoxy resin composition having excellent performance in impregnating fiber base materials, heat resistance, and attenuation, and a cured product using the same.

Epoxy resin has excellent processability and brings out various properties of the cured product such as high heat resistance, high insulation reliability, high rigidity, high adhesiveness, and high corrosion resistance. It is used in large quantities in a variety of applications, including plates, sealants), matrix resins for composite materials such as CFRP, structural adhesives, and heavy-duty anti-corrosion paints.

On the other hand, cured epoxy resins have low elongation at break, low fracture toughness, and low peel strength, so when used as matrix resins for composite materials or as structural adhesives, which require these properties, rubber-modified or polyurethane-modified products are used. The above characteristics have been improved through various modifications such as.

Regarding polyurethane modification, for example, Patent Documents 1 and 2 contain diglycidyl ether (A) of a bisphenol A-alkylene oxide adduct, an epoxy resin, and a polyurethane dispersed in the epoxy resin, and the polyurethane contains an epoxy resin. Disclosed is an epoxy resin/polyurethane mixture (B) which is a polyurethane obtained by reacting a polyisocyanate compound and a curing agent capable of reacting with the polyisocyanate compound in a resin.
Patent Document 3 discloses a resin composition containing a compound having an epoxy group and a polyurethane containing a structural unit represented by general formula (II) in the molecule.
Patent Document 4 discloses an 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 extender. Obtained by using a predetermined amount of (a) and reacting a medium-high molecular weight polyol compound (b) and a polyisocyanate compound (c) in a predetermined amount, and then adding a predetermined amount of a low molecular weight polyol compound (d). A polyurethane modified epoxy resin is disclosed.
Patent Document 5 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 essential reaction raw materials, and the polycarbonate polyol (C) is in a predetermined amount.
Patent Document 6 discloses 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 the molecular chain, and a curing agent (C). An epoxy resin composition obtained by blending, in which (A) and (B) are compatible before the curing reaction, after the curing reaction, (A) forms a sea structure, and (B) Disclosed is an epoxy resin composition for fiber-reinforced composite materials in which an island structure is formed and the resulting cured product of the epoxy resin composition has a sea-island phase separation structure.

As other techniques, Patent Documents 7 to 9 disclose epoxy resin compositions containing an epoxy resin, a thermoplastic resin such as a polyethersulfone resin, and a curing agent.
Patent Document 10 discloses improving impact properties by forming a resin layer containing particles of a thermoplastic resin having a polyarylether skeleton, a thermoplastic resin, and a thermosetting resin.

However, even with these patent documents, the required characteristics may still not be fully satisfied. The present invention proposes a polyurethane-modified epoxy resin that satisfies the physical properties required for various uses and has excellent damping properties. The resin itself has damping properties, which prevents deterioration of mechanical properties, thermal properties, and chemical resistance of the cured product due to the addition of elastomers with poor heat resistance and solvent resistance, and prevents stress relaxation layers (adhesive layers) from deteriorating. It is expected that the formation of such a material will also become unnecessary.

Japanese Patent Application Publication No. 2007-284467 Japanese Patent Application Publication No. 2007-284474 Japanese Patent Application Publication No. 2007-224144 Unexamined Japanese Patent Publication No. 2016-11409 JP2017-226717A JP2017-82128A Japanese Patent Application Publication No. 2005-105151 Japanese Patent Application Publication No. 2007-284545 Japanese Patent Application Publication No. 2008-144110 WO2019/098243

The present invention is a urethane-modified epoxy resin used in casting materials, composite materials, structural adhesives, etc., which has a high glass transition temperature, lower viscosity, and excellent fiber impregnation properties, and is suitable for filament winding (FW) molding and pultrusion molding. The object of the present invention is to provide a novel polyurethane-modified epoxy resin composition which has high damping properties and a cured product thereof.

The present invention provides a polyurethane unmodified epoxy resin (A) having a structure derived from a polyether polyol and a structure derived from a polyisocyanate, and in which the structure having an isocyanate group at the end of the molecular chain is averaged in the molecule. A polyurethane-modified epoxy resin (B) having a structure that has reacted with the hydroxyl group of an epoxy resin having two or more epoxy groups, and a curing agent (C) as essential components, and the total amount (solid content) of the epoxy resin composition. A polyurethane-modified epoxy resin composition containing 20 to 70% by weight of a polyurethane-modified epoxy resin (B) in which the component (A) and the component (B) are compatible with each other, and the curing after the curing reaction. As a material, component (A) and component (B) form a phase-separated structure, and the loss coefficient (tan δ) was measured using a dynamic viscoelasticity device under the conditions of a frequency of 10 Hz and a temperature increase rate of 2°C/min. is 0.03 or more in the temperature range of -40°C to 40°C, and the viscosity at 25°C measured with an E-type viscometer is 50 Pa s or less. be.

In the polyurethane-modified epoxy resin composition of the present invention, it is desirable that in the polyurethane-modified epoxy resin (B), 30 mol% or more of the structure derived from the polyether polyol is derived from polytetramethylene ether glycol (PTMG).
Further, in the epoxy resin having an average of two or more epoxy groups in the molecule, it is desirable that 1/3 or more of the number of moles of the epoxy resin to be reacted is an aliphatic epoxy resin.
Furthermore, the polyurethane-modified epoxy resin (B) has a weight average molecular weight of 8,000 or more, and the amount of the urethane component (described later) in component (B), that is, the blended amount of the polyol compound and the isocyanate compound, is the same as that of component (A). It is preferably 13.5% by weight or more based on the total amount of component (B).
Moreover, in the polyurethane-modified epoxy resin (B), it is preferable that the aliphatic epoxy resin is 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 fiber-reinforced composite materials obtained by impregnating reinforcing fibers with the composition, and fibers obtained from the resin composition. It is a reinforced composite material.
Furthermore, the present invention provides that the structure having a structure derived from a polyether polyol and a structure derived from a polyisocyanate, and having an isocyanate group at the end of the molecular chain has an average of two or more epoxy groups within the molecule. A polyurethane-modified epoxy resin having a structure that has reacted with the hydroxyl group of an epoxy resin having a structure, in which 30 mol% or more of the structure derived from the polyether polyol is derived from polytetramethylene ether glycol, and within the molecule The present invention is a polyurethane-modified epoxy resin characterized in that ⅓ or more of the moles of the epoxy resin having two or more epoxy groups on average are aliphatic epoxy resins.

The polyurethane-modified epoxy resin composition of the present invention has a low viscosity of 50 Pa·s or less at 25°C, has excellent fiber impregnating properties, suppresses a decrease in glass transition temperature, and allows optimal phase separation of the cured product. Because it has a high loss coefficient (tan δ), it is used as a matrix resin for composite materials for industrial, sports and leisure, civil engineering and construction applications that require damping properties, and resins used in adhesives. be suitable.

This is a stereoscopic microscope image showing the phase structure of the cured product (Example 10). This is a stereoscopic microscope image showing the phase structure of the cured product (Comparative Example 3).

The polyurethane-modified epoxy resin composition of the present invention contains a polyurethane-modified epoxy resin (B), a polyurethane-unmodified epoxy resin (A) as a polyurethane concentration adjuster, and a curing agent (C) as essential components; It is characterized by containing 20 to 70% by weight of the polyurethane-modified epoxy resin (B) based on the total amount (solid content) of the resin composition.
The resin composition of the present invention may contain a curing accelerator (D) and further inorganic fillers such as calcium carbonate, talc, and titanium dioxide as extenders and reinforcing materials, if necessary.

The polyurethane-modified epoxy resin (B) used in the present invention has two or more epoxy groups on average in the molecule, such as liquid bisphenol type epoxy resin (a-1) or aliphatic type epoxy resin (a-2). [Hereinafter, these may be collectively referred to as epoxy resin (a). ], a polyether polyol compound such as polytetramethylene ether glycol (PTMG) (b-1), and a polyisocyanate compound (c) are used as essential components. From the viewpoint of optimizing physical properties and viscosity, fine-tuning compatibility, and controlling molecular weight, polyol compounds (b-2) with a number average molecular weight of 500 or more made of materials other than PTMG, and low polyol compounds with a number average molecular weight of less than 500 as chain extenders are used. A molecular weight polyol compound (d) may be used as appropriate. The number average molecular weight described here is a value converted from a hydroxyl value (hydroxyl value), and a value measured by a measuring method according to JIS K1557 is usually used as the hydroxyl value. The same applies hereafter.
Each component of the polyurethane-modified epoxy resin (B) will be explained below.

式中、Ｒ_１はそれぞれ独立に、Ｈ又はアルキル基であり、ａは０～１０の数である。Ｒ_１がアルキル基である場合、好ましくは炭素数１～３の範囲であり、より好ましくは炭素数１である。 As the epoxy resin (a) having an average of two or more epoxy groups in the molecule, it is preferable to use the above-mentioned (a-1) and (a-2). Having an average of two or more epoxy groups in the molecule is advantageous in that various physical properties can be developed through subsequent reaction with a curing agent.
Here, the epoxy resin (a-1) is a component suitable for exhibiting heat resistance and mechanical properties, and is liquid at room temperature, and from this viewpoint, it is preferable that the epoxy equivalent is 300 g/eq or less. More preferably, the epoxy resin has an epoxy equivalent of 150 to 300 g/eq and a hydroxyl equivalent of 800 to 3,600 g/eq. Specifically, a secondary hydroxyl group-containing bisphenol-type epoxy resin represented by the following general formula (1) and having an epoxy equivalent of 150 to 200 g/eq and a hydroxyl group equivalent of 2000 to 3000 g/eq is suitable.

In the formula, R ₁ is each independently H or an alkyl group, and a is a number from 0 to 10. When R ₁ is an alkyl group, it preferably has 1 to 3 carbon atoms, more preferably 1 carbon number.

式中、ａ１、ａ２は０～１０の数である。
式（１）、式（１ａ）、式（１ｂ）において、繰り返し数ａ、ａ１又はａ２の平均値（数平均）は１～５の範囲であり、好ましくは１～３の範囲である。 Particularly preferred epoxy resins (a-1) are bisphenol A epoxy resins represented by formula (1a) and/or bisphenol F epoxy resins represented by formula (1b).

In the formula, a1 and a2 are numbers from 0 to 10.
In formula (1), formula (1a), and formula (1b), the average value (number average) of the number of repetitions a, a1, or a2 is in the range of 1 to 5, preferably in the range of 1 to 3.

In addition, the epoxy resin (a-2) is a suitable component for lowering the viscosity of polyurethane-modified epoxy resins and compositions using the same, and has a viscosity of 100 mPa·s or more and 5000 mPa·s or less at 25°C. is preferred. In addition, any epoxy resin containing a hydroxyl group in its structure may be used, and it may have either a primary hydroxyl group or a secondary hydroxyl group, and either of these may be used in the reaction. Hydroxyl groups of incomplete epoxy resins may also be used. From the viewpoint of lowering the viscosity of a polyurethane-modified epoxy resin and a composition using the same, the aliphatic epoxy resin (a-2) has a higher content of the reacting epoxy resin (a) than the above-mentioned epoxy resin (a). It is preferable to use ⅓ or more of the total number of moles. More preferably, it is 1/2 or more of the number of moles, and still more preferably 2/3 or more of the number of moles. In addition, regarding the "number of moles" here, it is preferable to adopt a value obtained by dividing the usage amount (mass) of each epoxy resin by the hydroxyl group equivalent and converting it per unit functional group. In the present invention, one of the secondary hydroxyl groups of the multimer of epoxy resins (a-1) and (a-2) (for example, when a=1 or more in the above formula (1)) reacts with an isocyanate group. It is assumed that the urethane prepolymer is formed in a manner that caps the ends of the urethane structure, but when a = 2 or more, it tends to contribute to the extension of the molecular chain without capping the ends of the urethane structure. A tendency toward gelation is also assumed due to the increase in molecular weight. Therefore, since the a=1 form accounts for most of the forms other than the a=0 form, it is assumed that the value divided by the hydroxyl group equivalent approximately indicates the number of the n1 form. Therefore, this number is expressed as the number of moles, and the ratio of the numbers is expressed as the molar ratio.

The aliphatic epoxy resin (a-2) is preferably a polyglycidyl ether of a dihydric or higher aliphatic alcohol, and may have an alicyclic skeleton. Examples of divalent aliphatic alcohols include 1,4-butanediol, 3-methyl-1,5-pentanediol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, 1,9-nonanediol, and cyclohexanedimethanol. , propylene glycol, etc. Further, examples of trivalent or higher aliphatic alcohols include glycerin, trimethylolpropane, trimethylolethane, tetramethylolpropane, sorbitol, pentaerythritol, and the like. Among them, polyglycidyl ether of trimethylolpropane is preferred from the viewpoint of viscosity, compatibility, mechanical properties, and the like.

As the polyether polyol compound (included in the polyol compounds described below), compounds having a primary hydroxyl group at the terminal, such as the following (b-1) and (b-2), can be suitably used. can. For example, polytetramethylene ether glycol (PTMG) (b-1) is a linear polyether glycol having primary hydroxy groups at both ends represented by the following formula (2a), and has a number average molecular weight of 200. There are some that range from around 4,000 to over 4,000. Note that the polyether polyol compound is included in the polyol compound.

In the present invention, the number average molecular weight is preferably about 500 to 4,000, and from 2,000 to 4,000 in consideration of compatibility with the resin and development of attenuation properties.

ここで、Ｒ_２はＨ又はメチル基であり、ｂ１、ｂ２、ｂ３は独立に１～５０の数で、ｃは０又は１の数である。 Examples of the polyether polyol compound (b-2) other than PTMG include compounds represented by the following formulas (2b) to (2d), such as polyethylene glycol (PEG), polypropylene glycol (PPG), polyethylene propylene glycol (PEPG), etc. ), two or more types of alkylene oxide copolymers (for example, ethylene oxide/propylene oxide copolymers), and the like. In addition, as (b-2), polyol compounds such as lactone-modified polyols, polyester polyols, and polycarbonate polyols can be used as long as they do not impede the purpose of the present invention, and these can be used singly or in combination of two or more. Can be used. These (b-2) components also preferably have the same number average molecular weight as (b-1).

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

ここで、ｑ１、ｑ２、ｑ３、ｑ４は独立に１～２０の数である。

Here, q1, q2, q3, and q4 are independently numbers from 1 to 20.

ここで、ｒ，ｓ，ｔは独立に１～２０の数であり、ｎは１～５０の数である。

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

The polyisocyanate compound (c) may have two or more NCO groups, but preferably two. It is preferably represented by the general formula (3), in which R ₄ is a divalent group selected from formulas (i) to (vi). Among these, those having excellent compatibility with the epoxy resin (a) are preferably selected.

Specific examples include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), hydrogenated xylylene diisocyanate (HXDI), isophorone diisocyanate (IPDI), naphthalene diisocyanate, and the like. Each may be any one of the isomers or a mixture of isomers.

Here, R ₄ is preferably a divalent group selected from formulas i to vi. Note that in formulas ii and v, the methyl group is omitted.

In particular, 4,4'-diphenylmethane diisocyanate (MDI) represented by formula (3a) is more preferable from the viewpoints of low molecular weight, no thickening property, low cost, and safety. Further, tolylene diisocyanate (TDI) (2,4-TDI and/or 2,6-TDI) and m-xylylene diisocyanate (XDI) as exemplified in Examples below can also be used more preferably.

ここで、Ｒ_５は式viiで表されるアルキレン基であり、ｇは１～１０の数である。 The low molecular weight polyol compound (d) is a polyol compound having a number average molecular weight of less than 500. Preferably it is less than 200. Used as a chain extender. Preferably, it is a diol compound represented by formula (4) and having two primary hydroxyl groups.

Here, R ₅ is an alkylene group represented by formula vii, and g is a number from 1 to 10.

Specific examples of the low molecular weight polyol compound (d) include polyhydric alcohols such as 1,4-butanediol and 1,6-pentanediol. In particular, 1,4-butanediol is more preferred in terms of easy availability and good balance between price and properties.

Next, any or all of the components (a-1), (a-2), (b-1), (b-2), (c) and (d) exemplified above were used. Polyurethane-modified epoxy resin will be explained, including the reaction mechanism. Each component can be used alone or in combination of two or more.

The OH groups in the epoxy resin (a) (eg, (a-1), (a-2)) are mainly secondary OH groups. On the other hand, the OH groups of polytetramethylene glycol (PTMG) (b-1) and the polyether polyol compound other than PTMG (b-2) are mainly primary OH groups. Therefore, epoxy resin (a), polytetramethylene ether glycol (PTMG) (b-1) and/or polyether polyol compound other than PTMG (b-2), polyisocyanate compound (c), etc. were charged and reacted. At this time, the primary OH groups of (b-1) and (b-2) and the NCO group of the polyisocyanate compound (c) react preferentially.

Typically, the primary OH groups in (b-1) and (b-2) and the NCO group in (c) react first, and the urethane group at the end of the NCO group to which they are bonded is formed. A prepolymer (P1) is produced. That is, the urethane prepolymer (P1) is formed by combining a structure having a structure derived from a polyether polyol derived from (b-1) and (b-2) and a structure derived from a polyisocyanate compound. Here, the structure derived from polyether polyol refers to the structure remaining after removing at least one hydroxyl group (which may partially contain) at the molecular end of the polyether polyol compound. Moreover, the structure derived from a polyisocyanate compound refers to the structure remaining after removing at least one isocyanate group (which may partially contain) at the molecular end of the polyisocyanate compound. Preferably, it is produced as a urethane prepolymer (P1) having NCO groups at both ends after the reaction. Then, the OH groups (preferably secondary OH groups) in the epoxy resin (a) react with the terminal NCO groups of the urethane prepolymer (P1) to form urethane bonds, and the urethane prepolymer (P1) It is considered that the urethane prepolymer (P2) has the epoxy resin (a) added to both ends or one end of the urethane prepolymer (P2).

That is, the urethane prepolymer (P) is a urethane prepolymer (P1) with an NCO group terminal and an epoxy resin (a) [a structure derived from epoxy resin (a)] added to both ends or one end of P1. It is thought to be a mixture of polymer (P2), but since the molar ratio of NCO groups is large and epoxy resin is used in large excess, urethane prepolymer (P2) is mainly produced with epoxy resin added to both ends of P1. it seems to do. Here, the epoxy resin-derived structure refers to the structure remaining after removing at least one hydroxyl group (which may partially contain) from the epoxy resin.

The charging ratio of epoxy resin (a) is 50 to 85% by weight based on the total amount of components (a), (b-1), (b-2), (c), and (d). preferable. As the charging ratio of the epoxy resin (a) increases, both ends or one end of the urethane prepolymer (P1) are sealed with the epoxy resin (a), the terminal NCO group is consumed, and the The amount of urethane prepolymer (P2) that does not react with the molecular weight polyol compound (d) increases, and the proportion of the initial urethane prepolymer (P1) whose terminal end is an NCO group decreases, and the terminal NCO group of P1 and the chain extender decrease. Since the amount of polyurethane produced by the reaction with the OH group of a certain low molecular weight polyol compound (d) decreases, the molecular weight distribution of the polyurethane-modified epoxy resin also shifts to the lower molecular weight side.

On the other hand, when the charging ratio of epoxy resin (a) is decreased, the amount of urethane prepolymer (P2) whose both ends or one end are sealed with epoxy resin (a) decreases, and the end remains as an NCO group. The proportion of the initial urethane prepolymer (P1) increases. Therefore, the amount of polyurethane produced by the reaction between the terminal NCO group of P1 and the OH group of the low molecular weight polyol compound (d), which is a chain extender, increases, and the molecular weight distribution of the polyurethane-modified epoxy resin also shifts to the high molecular weight side. shift.

Regarding epoxy resin (a), for example, (a-1) and (a-2) are often a mixture of a monomer with a repeating number a of 0 and one or more multimers; In this case, the epoxy group has a secondary OH group generated by ring opening. This secondary OH group is reactive with the NCO group of the polyisocyanate compound (c) or the terminal NCO group of the urethane prepolymer (P), so it is When it has a secondary OH group (for example, a=1 or more in formula (1)), it reacts. In addition, when the epoxy resin (a) does not have an OH group (for example, a=0 body in formula (1), etc.), it does not participate in this reaction. As described above, the polyurethane-modified epoxy resin (B) in the present invention includes each of the components (a-1), (a-2), (b-1), (b-2), (c) and Complex structures reacted using any or all of (d), and epoxy resins (a) that do not have the above-mentioned OH groups, although they are not considered to be directly involved in the reaction or expression of functions. Since it is understood that the component (B) is in the form of a mixture that cannot be completely distinguished or excluded, it is impossible or impractical to directly identify the component (B) by its structure or characteristics. There are some circumstances (so-called impossible/impractical circumstances) where this is not possible.

The reason why the polyurethane-modified epoxy resin composition of the present invention exhibits damping properties is that the polyurethane-modified epoxy resin portion undergoes phase separation in the epoxy resin composition. In general, there are many reports that phase separation causes the formation of a sea-island structure, but in the present invention, the state is not a sea-island structure in which the islands exist in a spherical shape, but a structure in which the islands begin to connect with each other. Such a phase-separated structure is called an interpenetrating structure or an interconnected structure, and in the present invention, a phase-separated structure having at least partially an interpenetrating structure or an interconnected structure is preferable. When using a polyurethane-modified epoxy resin in which 30 mol% or more of the polyether polyol compound having a structure derived from a polyether polyol is polytetramethylene ether glycol (PTMG), the phase-separated island part (polyurethane-modified epoxy resin part) The Tg of the island part has a gentle peak in the -40℃ to 40℃ range, and the island part is almost incompatible with the sea part (epoxy resin part) and phase separates, creating a structure in which the island parts begin to connect with each other. By doing so, a high loss coefficient (tan δ) can be exhibited in the −40° C. to 40° C. range and the temperature range around it. Therefore, in order to obtain the phase-separated structure of the present invention, it is necessary to control the size and number of island parts, compatibility with the sea part, etc.

One of the factors controlling the phase separation structure is the amount of urethane moiety. The urethane part is the part in the polyurethane-modified epoxy resin where the polyether polyol compound and the polyisocyanate compound react, and the size, number, shape, etc. of the island parts can vary depending on the amount of the urethane part in the composition. It's going to change. Images of examples of phase separation are shown in Figures 1 and 2. In the present invention, the amount of the urethane component (described later) in the polyurethane-modified epoxy resin (B), that is, the amount of the polyol compound and the polyisocyanate compound, is the component. It can be seen that when the total amount of (A) and component (B) is 17% by weight, phase separation occurs to a level where the sea-island structure is clearly visible as shown in Figure 1, but when it is 13% by weight, as shown in Figure 2. It can be seen that the structure of the island is minute. In a state where a sea-island structure is completely formed and the islands exist alone with a size of several nanometers to several tens of nanometers, tan δ is low, and as the islands aggregate up to a size of several hundred nm to several μm, the sea-island structure begins to have shading. A behavior in which tan δ increases is confirmed. Furthermore, as the phase separation progresses further, a phase-separated structure in which islands are connected up to a size of several tens of micrometers to several hundred micrometers is formed, and a more suitable tan δ is exhibited. However, if the phase separation size is too large, mechanical properties will deteriorate. In order to obtain the phase-separated structure of the present invention, the phase-separated island size is preferably 10 nm to 200 μm, more preferably 100 nm to 100 μm, and particularly preferably 1 μm to 100 μm.

It is not only the molecular weight of the polyurethane-modified epoxy resin that controls the size of the islands that undergo phase separation, but also the compatibility with the sea area. If the compatibility is high, the island portions will be compatible with the sea portions when the epoxy resin composition is cured, and phase separation will not proceed, making it impossible to form a desired phase-separated structure. Therefore, in order to form islands of a desirable size and number, the polyurethane-modified epoxy resin of the islands needs to have a certain molecular weight and be incompatible with the unmodified epoxy resin of the sea. In addition, as time passes during phase separation, the incompatible island portions gradually connect with each other to form large domains, which causes deterioration of mechanical properties. Therefore, it is necessary to select the optimum molecular weight and composition of the polyurethane-modified epoxy resin depending on the viscosity of the resin composition and the curing conditions (curing temperature, curing time, temperature increase rate) depending on the application.

Since the polyurethane-modified epoxy resin (B) has a gentle peak in the Tg of the phase-separated islands in the -40°C to 40°C range, 30 mol% or more of the structure derived from the polyether polyol compound is polytetra A structure derived from methylene ether glycol (PTMG) is preferred. It is more preferably used in an amount of 50 mol% or more, still more preferably 75 mol% or more, and most preferably 100 mol%. The mole used here is the value obtained by dividing the weight of each component by the number average molecular weight.

Since the phase-separated island part is not compatible with the sea part, the polyurethane-modified epoxy resin (B) has a weight average molecular weight of 8000 or more, and the amount of the urethane component described below in component (B), that is, the polyol compound and the polyisocyanate compound. It is preferable that the blending amount is 13.5% by weight or more based on the total amount of component (A) and component (B). The weight molecular weight is more preferably 10,000 or more, still more preferably 12,000 or more and 45,000 or less, and even more preferably 12,000 or more and 35,000 or less. In addition, in order to form a desirable phase-separated structure, the amount of the urethane component (described below) in component (B), that is, the amount of the polyol compound and polyisocyanate compound, is determined relative to the total amount of component (A) and component (B). , more preferably 13.5% by weight or more and 19% by weight or less.

As a method for producing the polyurethane-modified epoxy resin (B) used in the present invention, for example, (a-1), (a-2), etc. as the epoxy resin (a) are mixed with polytetramethylene ether as a polyether polyol compound. Glycol (PTMG) (b-1), a polyether polyol compound other than PTMG (b-2), a polyisocyanate compound (c), and a low molecular weight polyol compound with a number average molecular weight of less than 500 as a chain extender ( (b-1), (b-2) and the polyisocyanate compound (c) are reacted in the presence of the epoxy resin (a). Reaction 1). In this reaction 1, the reaction between (b-1), (b-2) and the polyisocyanate compound (c) occurs preferentially to produce the urethane prepolymer (P1). Thereafter, a reaction between the urethane prepolymer (P1) and the epoxy resin (a) occurs, and a urethane prepolymer (P2) in which both ends of P1 are mainly epoxidized is produced.

The reaction between the urethane prepolymer (P1) and the epoxy resin (a) is carried out by reacting the OH groups (mainly low-reactive secondary OH groups) in the epoxy resin (a) with the NCO groups of P1 to form the urethane prepolymer (P1) and the epoxy resin (a). Since it is necessary to form bonds, the reaction temperature is preferably in the range of 80 to 150°C, and the reaction time is preferably in the range of 1 to 5 hours.

Thereafter, if necessary, the molar ratio (P) of the NCO groups in the urethane prepolymer (P1) and the OH groups in the low molecular weight polyol compound (d) is adjusted to 0.9:1.0 to 1.0. : A low molecular weight polyol compound (d) is added so that the molecular weight is in the range of 0.9, and a polyurethane reaction is carried out (reaction 2). Note that the epoxy group of the epoxy resin and the OH group of the polyol compound (d) do not react because they are alcoholic OH groups.

The reaction temperature in reaction 2 is preferably in the range of 80 to 150°C, and the reaction time is preferably in the range of 1 to 5 hours. Therefore, milder conditions than for reaction 1 are sufficient.

In the process of the above reactions (reactions 1 and 2), a catalyst can be used as necessary. This catalyst is used for the purpose of sufficiently completing the formation of urethane bonds, and examples include amine compounds such as ethylenediamine, tin-based compounds, and zinc-based compounds.

In reaction 2, the remaining urethane prepolymer (P1) having NCO at both ends or one end reacts with the low molecular weight polyol compound (d) to extend the chain length and convert into polyurethane, and both ends are formed by epoxy resin (a The urethane prepolymer (P2), which is an adduct of ), remains unreacted with component (d).
When the low molecular weight polyol compound (d) is not used, when the polyisocyanate compound (c) is added, the terminal NCO reacts with each hydroxyl group to form a urethane prepolymer (P2).
The polyurethane-modified epoxy resin used in the present invention preferably has an epoxy equivalent in the range of 180 to 1000 g/eq and a viscosity at 120° C. in the range of 0.1 to 30 Pa·s.

By increasing or decreasing the blending amount of the polyurethane-unmodified epoxy resin (A), the polyurethane concentration in the polyurethane-modified epoxy resin composition can be increased or decreased. Here, the polyurethane concentration in the epoxy resin composition is calculated by the following formula using the components exemplified above, but the types of each component are not limited thereto.
Polyurethane concentration = {(b-1)+(b-2)+(c)+(d)}×100/{(A)+(B)+(C)}
In this case, (B)=(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 corresponding This is the weight of each component used. Note that when other components such as a curing accelerator (D) are added, these other components are added to the denominator.
In the present invention, the polyurethane concentration in the epoxy resin composition is preferably 5 to 30% by weight, more preferably 10 to 20% by weight.
In the polyurethane-modified epoxy resin (B), the urethane component concentration is preferably 20 to 50% by weight. Here, in the case of the above example, the urethane component concentration is {(b-1)+(b-2)+(c)+(d)}/{(a-1)+(a-2)+( b-1)+(b-2)+(c)+(d)}.

As the polyurethane unmodified epoxy resin (A) used in the polyurethane modified epoxy resin composition of the present invention, (a-1) as the above-mentioned epoxy resin (a) used as a raw material for the polyurethane modified epoxy resin (B), (a-2) etc. can be preferably used. That is, an epoxy resin that is not modified with polyurethane and is liquid at 30° C. is preferable. Among these, bisphenol A type epoxy resin and/or bisphenol F type epoxy resin are preferred from the viewpoint of easy availability and good balance between price and properties. As (a-2), polyglycidyl ether of trimethylolpropane is suitable from the viewpoint of viscosity, compatibility, mechanical properties, etc.

In the polyurethane-modified epoxy resin composition of the present invention, a trifunctional or higher functional epoxy resin can also be used as the polyurethane-unmodified epoxy resin (A) in order to adjust the viscosity or increase the Tg. If a polyfunctional epoxy resin is used, the crosslinking density will increase and the phase separation state will change or fracture toughness will be lost, so it is preferably used in an amount of 0.1 to 10% by weight based on the total weight of the composition. Examples of trifunctional or higher polyfunctional epoxy resins include phenol novolak epoxy resins, cresol novolac epoxy resins, glycidylamine epoxy resins such as tetraglycidyldiaminodiphenylmethane, tetrakis(glycidyloxyphenyl)ethane and tris(glycidyloxyphenyl). ) Glycidyl phenyl ether type epoxy resins such as methane, and glycidyl amine type and glycidylphenyl ether type epoxy resins such as triglycidylaminophenol. Further examples include epoxy resins obtained by modifying these epoxy resins, and brominated epoxy resins obtained by brominating these epoxy resins.

In this case, it is preferable to use an epoxy resin having a viscosity of 5000 mPa·s or less at 25°C. This lowers the viscosity of the composition, improves its impregnating properties into carbon fibers, and makes it possible to apply it to tow prepregs, pultrusion molding, and the like. Examples include glycidyl ether type epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, alicyclic epoxy resins, and the like. These epoxy resins can be used alone or in combination of two or more.

Examples of the glycidyl ether type epoxy resin include glycerol glycidyl ether type epoxy resin, butyl glycidyl ether type epoxy resin, phenyl glycidyl ether type epoxy resin, (poly)ethylene glycol diglycidyl ether type epoxy resin, and (poly)propylene glycol diglycidyl. Ether type epoxy resin, neopentyl glycol diglycidyl ether type epoxy resin, 1,4-butanediol diglycidyl ether type epoxy resin, 1,6-hexanediol diglycidyl ether type epoxy resin, trimethylolpropane polyglycidyl ether type epoxy resin , diglycerol polyglycidyl ether type epoxy resin, allyl glycidyl ether type epoxy resin, 2-ethylhexyl glycidyl ether type epoxy resin, p-(tert-butyl)phenyl glycidyl ether type epoxy resin, dodecyl glycidyl ether type epoxy resin, tridecyl glycidyl Examples include ether type epoxy resins. These glycidyl ether type epoxy resins can 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, terolahydrophthalic anhydride diglycidyl ester type epoxy resin, tertiary fatty acid monoglycidyl ester type epoxy resin, and o-phthalic acid diglycidyl ester. Examples include a type epoxy resin, a dimer acid glycidyl ester type epoxy resin, and the like. These glycidyl ester type epoxy resins can be used alone or in combination of two or more.

Examples of the glycidylamine type epoxy resin include m-(glycidoxyphenyl) diglycidylamine type epoxy resin, N,N-diglycidylaminobenzene type epoxy resin, and o-(N,N-diglycidylamino)toluene type. Examples include epoxy resin. These glycidylamine type epoxy resins can be used alone or in combination of two or more.

Examples of alicyclic epoxy resins include alicyclic diepoxy adipate type epoxy resins, 3,4-epoxycyclohexylmethylcarboxylate type epoxy resins, vinylcyclohexene dioxide type epoxy resins, and hydrogenated bisphenol A diglycidyl ether type epoxy resins. Examples include resin.

As the curing agent (C), it is preferable to use dicyandiamide (DICY) or a derivative thereof because it can be made into a single component with excellent storage stability and is easily available.

When the curing agent (C) is DICY, the amount of the curing agent (C) is determined by the number of moles of epoxy groups in all epoxy resins including the polyurethane-modified epoxy resin (B) and the unmodified polyurethane epoxy resin (A) and the active hydrogen group of DICY. It is preferable from the viewpoint of the properties of the cured product that the ratio of the number of moles is set in the range of 1:0.3 to 1:1.2, preferably 1:0.9 to 1:1.1.

The urethane-modified epoxy resin composition of the present invention can further contain a curing accelerator (D). As the curing accelerator (D), an imidazole-based curing aid is suitably used in order to impregnate reinforcing fibers during mixing and suppress viscosity increase, as well as to satisfy heat resistance during curing. Examples of imidazole curing aids include 2-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, It is preferable to use 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4',5'-dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, and the like. Furthermore, imidazole compounds containing a triazine ring are preferred, and examples of such compounds 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 is more preferably used from the viewpoint that it can be cured in a short time. The imidazole compounds containing a triazine ring may be used alone or in combination of two or more.

On the other hand, depending on the application or construction method, there may be cases where it is not necessary to cure the material in such a short period of time as described above. In such cases, crystalline imidazole compounds such as 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid addition salt (2MA-OK), Urea compounds such as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) can be used. The amount of curing accelerator (D) is 0.1 to 5 wt% based on the total of all epoxy resins including polyurethane modified epoxy resin (B) and polyurethane unmodified epoxy resin (A) and curing agent (C). A range is preferred.

The epoxy resin composition of the present invention can contain a mold release agent (E) as required depending on the use and construction method. There are two types of mold release agents, such as liquid mold release agents and solid (powder) mold release agents.As liquid mold release agents, even low-viscosity compositions can be mixed uniformly at room temperature (10 to 30℃). It suffices if it is liquid at ℃). Further, by mixing a mold release agent into the resin, pultrusion moldability is improved. This improves the orientation of the fibers in the molded product, which improves the mechanical properties of the molded product, such as its compressive strength, and improves its adhesion with adhesives due to its smooth surface.

The amount of the mold release agent blended is preferably 0.1 to 6 parts by weight based on 100 parts by weight of the total epoxy resin. More preferably, it is 0.1 to 4 parts by mass. If it is less than 0.1 part by mass, sufficient mold releasability may not be obtained. Moreover, if more than 6 parts by mass is added, the strength of the molded product may decrease, and the adhesion and adhesion may decrease. The mold release agents may be used alone or in combination of two or more.

Such a liquid mold 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 examples include MOLDWIZ INT-1324, 1324B, 1836, 1846, 1850, 1854, and 1882 manufactured by Tomoe Kogyo Co., Ltd., which are polycondensed organic acids and glycerides.

Solid (powder) mold release agents include animal waxes such as shellac wax, beeswax, and spermaceti, vegetable waxes such as carnauba wax and white wax, and mineral waxes such as paraffin wax and microcrystalline wax. Waxes and synthetic waxes include Fischer-Tropsch wax, polyethylene wax, polypropylene wax, etc., and are preferably in powder form so that they can be uniformly dispersed in the epoxy resin composition, and which melt at the temperature during molding and curing. , it is desirable that it has the property of being soluble.

The cured product of the present invention is obtained by subjecting the epoxy resin composition to a curing reaction. The method for obtaining the cured product may be based on a general method for curing a curable resin composition, and, for example, the heating temperature conditions may be appropriately selected depending on the type of curing agent to be combined, the use, etc. For example, a method may be mentioned in which the epoxy resin composition is heated in a temperature range of about room temperature to 250°C. As for the molding method, it is possible to use a general method for producing curable resin compositions.

Since the cured product of the present invention has excellent heat resistance and excellent damping properties, it is preferable that the glass transition temperature (Tg) of the cured product is 120°C or higher, and -40°C to The loss coefficient (tan δ) is 0.03 or more in a temperature range of 40°C.

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 fiber-reinforced composite material, and then molding and curing the composition. Here, the reinforcing fibers may be twisted yarns, untwisted yarns, or non-twisted yarns, but untwisted yarns and non-twisted yarns are preferable because they have excellent moldability in the fiber-reinforced composite material. Furthermore, the reinforcing fibers can be in the form of one in which the fibers are aligned in one direction or a woven fabric. Fabrics can be freely selected from plain weave, satin weave, etc. depending on the part and purpose of use. Specifically, carbon fibers, glass fibers, aramid fibers, boron fibers, alumina fibers, silicon carbide fibers, etc. are used because of their excellent mechanical strength and durability, and these can be used alone or in combination of two or more types. You can also. Among these, carbon fibers are particularly preferable because they provide good strength to the molded product, and various types of carbon fibers such as polyacrylonitrile, pitch, and rayon fibers can be used.

The method for obtaining a fiber-reinforced composite material from the epoxy resin composition of the present invention is not particularly limited. Continuous carbon fibers arranged in one direction to form a sheet, materials such as carbon fiber fabrics impregnated with resin, carbon fiber base materials with a resin layer placed on at least one surface, and those surfaces. A method in which a fiber layer is further arranged on the varnish, and a method in which unidirectional reinforcing fibers in which reinforcing fibers are aligned in one direction are immersed in the varnish obtained above (before curing by pultrusion method or filament winding method, Tow prepreg), or reinforcing fiber sheets or fabrics are stacked and set in a mold, and then resin is injected into the mold and impregnated by applying pressure, or by reducing pressure inside the mold (RTM curing) previous state), etc.

In the fiber-reinforced composite material of the present invention, the volume content of reinforcing fibers relative to the total volume of the molded product is preferably 40% to 85%, and more preferably 50 to 75% from the viewpoint of strength. When the volume content is less than 40%, the content of the epoxy resin composition is too high, and the resulting cured product may lack elastic modulus or strength, or may not be able to satisfy the required properties. There is. Furthermore, if the volume content exceeds 85%, the resin in the reinforcing fibers will be insufficient, leading to insufficient adhesion and the generation of voids, resulting in insufficient elastic modulus and strength of the cured product, and reduced interfacial adhesion. There are cases.

Next, the present invention will be specifically explained based on Examples. The present invention is not limited to this specific example, and various modifications and changes can be made without departing from the gist of the present invention.

The evaluation method for physical properties is as follows.
(1) Determination of the presence or absence of residual NCO groups by IR: After dissolving 0.05 g of the obtained polyurethane-modified epoxy resin in 10 ml of tetrahydrofuran, it was applied onto a KBr plate using a micro spatula plate, and the mixture was heated at room temperature for 15 minutes. A sample for IR measurement was prepared by drying and evaporating tetrahydrofuran. This was set in an FT-IR Spectrum-One manufactured by PerkinElmer, and it was determined that there were no residual NCO groups when the stretching vibration absorption spectrum at 2270 cm ^-1 , which is the characteristic absorption band of NCO groups, disappeared.
(2) Epoxy equivalent: Quantified according to JIS K 7236.
(3) Hydroxyl group equivalent: 25 ml of dimethylformamide is placed in a 200 ml Erlenmeyer flask with a glass stopper, and a sample containing 11 mg/equivalent or less of hydroxyl groups is accurately weighed and added and dissolved. Add 20 ml of 1 mol/L-phenylisocyanate toluene solution and 1 ml of dibutyltin malate catalyst solution using a pipette, shake well to mix, seal tightly, and allow to react for 30 to 60 minutes. After the reaction is complete, add 20 ml of 2 mol/L-dibutylamine toluene solution, shake well to mix, and leave to stand for 15 minutes to react with excess phenyl isocyanate. Next, 30 ml of methyl cellosolve and 0.5 ml of bromcresol green indicator are added, and excess amine is titrated with a standardized methyl cellosolve perchlorate solution. Since the indicator changed from blue to green and then yellow, the first point at which it turned yellow was taken as the end point, and the hydroxyl equivalent was determined using the following formulas i and ii.
Hydroxyl group equivalent (g/eq)=(1000×W)/C(SB)...(i)
C: Concentration of methyl cellosolve perchlorate solution mol/L
W: Sample amount (g)
S: Titration amount of methyl cellosolve perchlorate solution (ml)
B: Titration amount of methyl cellosolve perchlorate solution required for blank test during titration (ml)
C=(1000×w)/{121×(sb)}...(ii)
w: Amount of tris-(hydroxymethyl)-aminomethane weighed for standardization (g)
s: Titration amount of methyl cellosolve perchlorate solution required for titration of tris-(hydroxymethyl)-aminomethane (ml)
b: Titration amount of methyl cellosolve perchlorate solution required for blank test during standardization (ml)
(4) Hydroxyl value: Measured using a measurement method based on JIS K1557.
(5) Viscosity: The viscosity value at 25°C was measured using an E-type viscometer cone plate type. The epoxy resin composition of the present invention was prepared, 0.8 mL of which was used for measurement, and the value 60 seconds after the start of the measurement was taken as the viscosity value.

(6) Glass transition temperature (Tg): The intersection of the baseline and the tangent at the inflection point is measured as the glass transition temperature (Tg) using a differential scanning calorimeter (DSC) under the condition of a heating rate of 10°C/min. It was derived as
(7) Tensile test: A cured product molded into the shape of JIS K 7161 by mold casting was used as a test piece, and a tensile test was conducted at room temperature of 23°C using a universal testing machine to determine the tensile strength, tensile elongation, The tensile modulus of each was measured.
(8) Weight average molecular weight (Mw): Measured by gel permeation chromatography (GPC) under the following conditions.
Measuring device: HLC-8420GPC manufactured by Tosoh Corporation
Column: TSKgel SuperMultiporeHZ-M×2
Measurement conditions: temperature 40°C, eluent THF, flow rate 0.35mL/min
Sample: Polystyrene SRM706a
(9) Loss factor (tan δ): A test piece obtained by casting and processing a cured resin or molded product into a mold of 50 mmL x 10 mmW x 2 mmt was subjected to dynamic operation at a frequency of 10 Hz and a temperature increase rate of 2°C/min. The loss coefficient (tan δ) was measured using a viscoelastic device, and the value in the temperature range of -40°C to 40°C was calculated.
(10) Method for evaluating the phase separation structure of cured products: The resin compositions obtained in Examples and Comparative Examples were vacuum defoamed, and a curing accelerator was added using a casting plate with a 4 mm thick spacer sandwiched between metal plates. In the case of a non-fast curing system such as the one using 2MAOK in (D), a cured product was obtained at 120° C. for 1 hour and then at 150° C. for 1 hour. Further, in the case of a fast-curing system using 2MZA-PW as the curing accelerator (D), a cured product was obtained at 130° C. for 15 minutes. Thereafter, the cured product was cut out, trimmed with a microtome, and the surface was observed with a stereomicroscope or an atomic force microscope (AFM).

Stereo microscope:
Equipment: Leica stereo microscope M205C
Illumination: Coaxial illumination AFM:
Equipment: Dimension Icon type AFM (manufactured by Bruker-AXS)
Probe: NCHV (made by Bruker-AXS)
Tip curvature radius 10nm
Spring constant 42N/m (nominal value)
Mode: Tapping Mode
The judgment criteria are as follows.
×: Sea-island structure. It has a spherical island structure, the island size is on the order of tens of nanometers to several hundred nanometers, and the tan δ is low (on the order of 0.01 to 0.02).
○: Phase-separated structure with partially interpenetrating connections. Island aggregation occurs, the island size is on the level of several μm to several tens of μm, and tan δ is 0.03 or more.

The raw materials used are as follows.
Component A
Nippon Steel Chemical & Materials Epototh YD-128, Bisphenol A epoxy resin, epoxy equivalent 187g/eq, liquid Nippon Steel Chemical & Materials Epototh YDF-170, Bisphenol F epoxy resin, epoxy equivalent 170g/eq, liquid Nippon Steel Chemical & Material Epotote YH-300, polyglycidyl ether of trimethylolpropane, epoxy equivalent 142g/eq, liquid

Component B
Epoxy resin (a-1):
Epotote YDF-170 manufactured by Nippon Steel Chemical & Materials, bisphenol F type epoxy resin, epoxy equivalent 170g/eq, hydroxyl equivalent 2600g/eq, liquid epoxy resin (a-2):
Epotote YH-300 manufactured by Nippon Steel Chemical & Materials, polyglycidyl ether of trimethylolpropane, epoxy equivalent 142 g/eq, hydroxyl equivalent 837 g/eq, liquid

Polytetramethylene ether glycol (b-1) represented by the following formula (2a):
Mitsubishi Chemical PTMG2000, number average molecular weight 2000, hydroxyl group equivalent 1000g/eq
Mitsubishi Chemical PTMG3000, number average molecular weight 3000, hydroxyl group equivalent 1450g/eq

Polyol compound (b-2):
ADEKA Polyether P-3000, polypropylene glycol, number average molecular weight 3000, hydroxyl equivalent weight 1500g/eq

（ｃ－２）三井化学製コスモネートＴ－８０、トリレンジイソシアネート（ＴＤＩ）（２，４－トリレンジイソシアネートと２，６－トリレンジイソシアネートとの、質量割合が約８：２の混合物）

（ｃ－３）三井化学製タケネート５００、ｍ－キシリレンジイソシアネート（ＸＤＩ）

Polyisocyanate compound (c):
(c-1) Mitsui Chemical Cosmonate PH, 4,4'-diphenylmethane diisocyanate (MDI)

(c-2) Cosmonate T-80 manufactured by Mitsui Chemicals, tolylene diisocyanate (TDI) (mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate in a mass ratio of approximately 8:2)

(c-3) Mitsui Chemicals Takenate 500, m-xylylene diisocyanate (XDI)

Low molecular weight polyol compound (d):
1,4-butanediol (BD) (reagent), molecular weight 90

Component C:
EVONIK DICYANEX1400F, dicyandiamide

Component D:
Shikoku Kasei Kogyo crystalline imidazole, Curazole 2MZA-PW, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine

Example 1
Epototo YDF-170 as epoxy resin (a-1), Epototo YH-300 as epoxy resin (a-2), Mitsubishi Chemical PTMG3000 as polytetramethylene ether glycol, Cosmonate PH (MDI) as polyisocyanate (c-1) , 1,4-butanediol (BD) was used as a low molecular weight polyol compound and (d). The amounts used (unit: parts by weight) are shown in Table 1.
Epotote YDF-170, Epotote YH-300, and PTMG3000 were charged into a 1000 ml four-necked separable flask equipped with a nitrogen inlet tube, a stirrer, and a temperature controller, heated to 120° C., and stirred and mixed for 120 minutes. Next, Cosmonate PH was added and reacted at 120°C for 2 hours. Next, 1,4-butanediol was added and reacted at 120°C for 2 hours to obtain a polyurethane-modified epoxy resin (Example 1, UE1).
Completion of the reaction was confirmed by IR measurement when the absorption spectrum of the NCO group disappeared. The obtained polyurethane-modified epoxy resin (Example 1) had an epoxy equivalent of 226 g/eq and a weight average molecular weight of 14,000.

Examples 2-9, Comparative Examples 1-2
Polyurethane-modified epoxy resins (UE2 to UE9) were obtained by carrying out the reaction in the same manner as in Example 1, except that the raw material composition was as shown in Table 1. The epoxy equivalent is 241g/eq for UE2, 273g/eq for UE3, 237g/eq for UE4, 219g/eq for UE5, 234g/eq for UE6, 262g/eq for UE7, 212g/eq for UE8, and 251g/eq for UE9. eq, UE10 was 251g/eq, and UE11 was 258g/eq.

Next, examples of epoxy resin compositions and cured epoxy resin products using the polyurethane-modified epoxy resins obtained in Examples 1 to 9 and Comparative Examples 1 to 2 described above will be shown. The results are summarized in Table 2.

Example 10
As polyurethane modified epoxy resin (B), polyurethane modified epoxy resin UE1 obtained in Example 1, as polyurethane unmodified epoxy resin (A), Epotote YD-128, Epotote YH-300, as curing agent (C), dicyandiamide, curing accelerator As agent (D), 2MZA-PW was charged into a 200 ml dedicated disposable cup with the formulation shown in Table 2, and stirred and mixed with vacuum degassing for 5 minutes using a rotating/revolution laboratory vacuum planetary mixer to form a liquid. A resin composition was obtained. Here, the molar ratio of epoxy group to dicyandiamide was set to 1.0:0.5, and 140 g of a polyurethane-modified epoxy resin composition was prepared.
Next, this liquid resin composition was cast into a mold having a groove shape having the dimensions of a JIS K7161 test piece. The specimen size for tensile test is dumbbell type, the specimen size for fracture toughness is 100 mm L x 10 mm W x 4 mm t, and the specimen size for DMA test is 100 mm L x 10 mm W x 2 mm t.The liquid is poured into a mold or silicone frame suitable for measurement. It was cut to size and used. The castability at this time was at a level that allowed for sufficient casting. Next, the resin composition was poured into a mold that had been preheated to 130°C, and then placed in a hot air oven and cured by heating at 130°C for 5 minutes to prepare a cured epoxy resin test piece. did. Table 2 shows the test results using this test piece.

Examples 11 to 19, Comparative Examples 3 to 7
A resin composition and a cured product were obtained by carrying out the reaction in the same manner as in Example 10, except that the amount of raw materials charged was as shown in Table 2. Table 2 shows the test results using these test pieces.
By using the polyurethane-modified epoxy resin part of the present invention, curing can be completed in a short time of 130°C and 5 minutes, and it has low viscosity and excellent impregnation properties, and has excellent damping properties while exhibiting sufficient mechanical properties. A resin composition can be obtained.

The polyurethane-modified epoxy resin composition of the present invention has a low viscosity and excellent fiber impregnation properties, suppresses a decrease in glass transition temperature, and forms an optimal phase separation structure in the cured product, and has a high loss coefficient ( tan δ), it is useful as a matrix resin for composite materials for industrial use, sports leisure use, civil engineering and construction use, etc. that require damping properties, and resins blended with adhesives.

Claims (9)

Polyurethane unmodified epoxy resin (A), which has a structure derived from polyether polyol and a structure derived from polyisocyanate, and has an average of two or more structures in the molecule that have an isocyanate group at the end of the molecular chain. Contains as essential components a polyurethane-modified epoxy resin (B) having a structure that has reacted with the hydroxyl group of an epoxy resin having an epoxy group, and a curing agent (C), based on the total amount (solid content) of the epoxy resin composition. A polyurethane-modified epoxy resin composition containing 20 to 70% by weight of a polyurethane-modified epoxy resin (B), in which component (A) and component (B) are compatible, and the cured product after the curing reaction is: Component (A) and component (B) form a phase-separated structure, and the loss coefficient (tan δ) measured using a dynamic viscoelasticity device under the conditions of a frequency of 10 Hz and a heating rate of 2°C/min is -40. A polyurethane-modified epoxy resin composition, characterized in that it has a viscosity of 0.03 or more in the temperature range from °C to 40 °C, and a viscosity of 50 Pa·s or less at 25 °C as measured by an E-type viscometer. The polyurethane-modified epoxy resin composition according to claim 1, wherein in the polyurethane-modified epoxy resin (B), 30 mol% or more of the structure derived from the polyether polyol is derived from polytetramethylene ether glycol. In the polyurethane-modified epoxy resin (B), 1/3 or more of the number of moles of the epoxy resin having two or more epoxy groups on average in the molecule is an aliphatic epoxy resin. 1. The polyurethane-modified epoxy resin composition according to 1. The polyurethane-modified epoxy resin composition according to claim 1, wherein the polyurethane-modified epoxy resin (B) has a weight average molecular weight of 8,000 or more and a urethane component amount of 13.5% by weight or more. The polyurethane-modified epoxy resin composition according to claim 1, wherein in the polyurethane-modified epoxy resin (B), the aliphatic epoxy resin is polyglycidyl ether of trimethylolpropane. A cured product obtained by curing the polyurethane-modified epoxy resin composition according to any one of claims 1 to 5. A resin composition for a fiber-reinforced composite material, which is obtained by impregnating reinforcing fibers with the polyurethane-modified epoxy resin composition according to any one of claims 1 to 5. A fiber-reinforced composite material obtained from the resin composition for fiber-reinforced composite materials according to claim 7. The hydroxyl group of an epoxy resin that has a structure derived from a polyether polyol and a structure derived from a polyisocyanate, and has an isocyanate group at the end of the molecular chain has an average of two or more epoxy groups in the molecule. A polyurethane-modified epoxy resin having a structure reacted with
30 mol% or more of the structure derived from the polyether polyol is derived from polytetramethylene ether glycol,
A polyurethane-modified epoxy resin, characterized in that ⅓ or more of the number of moles of the epoxy resin having two or more epoxy groups on average in the molecule is an aliphatic epoxy resin.

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