Curable resin composition and molded article using the same

Abstract

To provide a curable resin composition capable of obtaining high strength and heat resistance while reducing a load on the environment by using a naturally occurring raw material.SOLUTION: There is provided a curable resin composition which comprises a urethane modified epoxy resin (A), a non-urethane modified epoxy resin (B) and a curing agent (C) as essential components, wherein the urethane modified epoxy resin (A) has a structure derived from a castor oil polyol and a structure derived from a polyisocyanate, the ratio of the structure derived from a castor oil polyol is 15 to 50 pts.wt. in 100 pts.wt. of the urethane modified epoxy resin (A) and the ratio of the structure derived from a polyisocyanate is 5 to 15 pts.wt. and the hydroxyl group equivalent of the castor oil polyol is 150 to 1500 g / eq.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a curable resin composition and a molded article using the same.

Background Art

[0002] Epoxy resins and compositions are excellent in heat resistance, electrical insulation, and adhesion to substrates, and have a wide range of applications such as electronic materials, paints, composite materials, and adhesives. For the high-functionalization of materials, further improvement in the properties of epoxy resins is required, and physical properties such as low viscosity, low dielectric, high strength, and high toughness are demanded.

[0003] As methods for making epoxy resin compositions high-strength and high-toughness, attempts have been made to add rubber components, rubber particles, or inorganic compound fillers, or to modify epoxy resins with polyols or polycarboxylic acids to control the chemical structure and express the desired properties (Patent Documents 1 to 4). These methods often lead to an increase in the viscosity of the resin composition and a decrease in heat resistance, and there is a need for a method of making the composition highly tough without reducing heat resistance or the like.

[0004] Attempts have been made to impart toughness by synthesizing urethane-modified epoxy resins using polyols, polyisocyanates, and epoxy resins as raw materials and adding them to resin compositions. Urethane-modified epoxy resins have urethane bonds in their structures, and can form hard segments in which urethane bonds aggregate by hydrogen bonds, and at the same time, can form soft segments by incorporating compounds exhibiting rubber elasticity such as polyols into the structure. Furthermore, by forming a crosslinked structure through the reaction of the urethane-modified epoxy resin and a curing agent, a cured product containing hard segments and soft segments can be obtained. In order to achieve both a high elastic modulus and toughness as a cured product, it is necessary to pay attention to the ratio of hard segments and soft segments, that is, the types, compositions, and molecular weights of epoxy resins, polyisocyanates, polyols, etc. used as raw materials of the urethane-modified epoxy resin.

[0005] By the way, efforts to reduce carbon dioxide emissions, so-called carbon neutral and carbon negative technologies, are attracting attention towards measures against global warming and the construction of a recycling-based society. In the chemical industry, efforts are being made to improve the resource recycling rate and design materials without using raw materials derived from petrochemicals. As an example, the creation of resin products using natural-derived raw materials is being considered.

[0006] Examples of natural-derived raw materials include linseed oil, soybean oil, castor oil, corn oil, turpentine oil, tall oil, sugarcane, etc. In addition to these, polyols and polycarboxylic acids extracted from these, and polyesters derived using these polyols and polycarboxylic acids, etc. can be mentioned. Also, compounds partially using natural-derived raw materials, such as those synthesized using both these natural-derived raw materials and petrochemical-derived raw materials, can be mentioned.

[0007] As examples of curable resin compositions using natural-derived raw materials, compositions using epoxidized linseed oil, epoxidized castor oil (castor oil polyglycidyl ether), etc. and a curing agent for epoxy resin have been proposed (Patent Documents 5 to 6). Also, a polyurethane composition using a polyol containing castor oil-modified trifunctional polyol and a polyisocyanate has been proposed (Patent Document 7). However, natural-derived compounds have problems such as a wide molecular weight distribution and low functional group purity, and thus the elastic modulus and heat resistance of the resulting cured product tend to be low, limiting their applications.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0009] An object of the present invention is to provide a curable resin composition that can reduce the environmental load by using natural-derived raw materials and has high strength and heat resistance.

[0010] As a result of investigations to solve the above problems, the present inventors focused on the properties and modification ratios of natural-derived raw materials used in the urethane-modified epoxy resin and the modification ratio of polyisocyanate in a curable resin composition containing a urethane-modified epoxy resin, and found that a molded product having a high elastic modulus and heat resistance can be obtained during curing as the resin composition, and thus completed the present invention.

Means for Solving the Problems

[0011] That is, the present invention is as follows. (1) A curable resin composition containing a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C) as essential components, wherein the urethane-modified epoxy resin (A) has a structure derived from castor oil polyol and a structure derived from polyisocyanate, in 100 parts by weight of the urethane-modified epoxy resin (A), the ratio of the structure derived from castor oil polyol is 15 to 50 parts by weight, and the ratio of the structure derived from polyisocyanate is 5 to 15 parts by weight, and the hydroxyl equivalent of the castor oil polyol is 150 to 1500 g / eq. (2) The urethane-modified epoxy resin (A) has a structure derived from a polyol (a) other than castor oil polyol, and in 100 parts by weight of the urethane-modified epoxy resin (A), the ratio of the structure derived from the component (a) is 0.4 to 4.0 parts by weight, and the hydroxyl equivalent of the component (a) is 30 to 100 g / eq. The curable resin composition according to (1). (3) The curable resin composition according to (1), wherein the weight ratio of the urethane bond in 100 parts by weight of the urethane-modified epoxy resin (A) is 3.0 to 10.0 parts by weight. (4) The curable resin composition according to (1), wherein the epoxy equivalent of the urethane-modified epoxy resin (A) is 250 to 500 g / eq. (5) The curable resin composition according to (1), wherein the curing agent (C) is at least one selected from the group consisting of amines, dicyandiamide, and derivatives of dicyandiamide that are liquid at 25°C.

[0012] (6) A molded article obtained by curing the curable resin composition according to any one of (1) to (5). [Advantages of the Invention]

[0013] According to the curable resin composition of the present invention, in addition to reducing the environmental load by including a component derived from a natural product among the constituent components of the urethane-modified epoxy resin (A) used, by setting the structures derived from each constituent component to an appropriate ratio, a molded article can be obtained that exhibits strength and heat resistance equal to or higher than those of conventional curable epoxy resin compositions without reducing the heat resistance. [Modes for Carrying Out the Invention]

[0014] Hereinafter, embodiments of the present invention will be described in detail. The present invention relates to a curable resin composition containing a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C) as essential components. The urethane-modified epoxy resin (A) has a structure derived from castor oil polyol and a structure derived from polyisocyanate. Here, among 100 parts by weight of the urethane-modified epoxy resin (A), the ratio of the structure derived from castor oil polyol is 15 to 50 parts by weight, and the ratio of the structure derived from polyisocyanate is 5 to 15 parts by weight, and the hydroxyl equivalent of the castor oil polyol is 150 to 1500 g / eq.

[0015] The curable resin composition of the present invention contains a urethane-modified epoxy resin (A), a non-urethane-modified epoxy resin (B), and a curing agent (C) as essential components. Hereinafter, the urethane-modified epoxy resin (A), the non-urethane-modified epoxy resin (B), and the curing agent (C) are also referred to as component (A), component (B), and component (C), respectively.

[0016] The weight average molecular weight Mw of the urethane-modified epoxy resin (A) used in the present invention, measured by Gel Permeation Chromatography (GPC), is preferably 5,000 to 100,000, more preferably 10,000 to 50,000. When Mw is less than 5,000, there is a tendency that the toughness cannot be enhanced when the resin composition is cured, and when Mw exceeds 100,000, the viscosity of component (A) tends to be extremely high.

[0017] In addition, among 100 parts by weight of the urethane-modified epoxy resin (A) used in the present invention, the ratio of the structure derived from the castor oil polyol (castor oil polyol ratio) is 15 to 50 parts by weight, preferably 18 to 45 parts by weight, and more preferably 20 to 40 parts by weight. When the ratio of the castor oil polyol is within this range, the phase derived from the castor oil polyol structure becomes an appropriate dispersed state when the resin composition is cured, and high heat resistance and toughness can be achieved simultaneously. Here, the structure derived from the castor oil polyol refers to the remaining structure obtained by removing at least one hydroxyl group (a part of the hydroxyl group may be included) at the molecular end of the castor oil polyol which is a constituent component of the component (A).

[0018] Here, as the main component of the castor oil, the triglyceride of ricinoleic acid represented by the following formula (1) can be mentioned, and this component is also treated as a castor oil polyol having a hydroxyl equivalent of about 350 g / eq. In addition, various polyols with different hydroxyl equivalents whose molecular weights and functional group numbers are adjusted can be obtained by purification, hydrolysis reaction, condensation reaction using castor oil as a raw material, transesterification reaction using petroleum-derived raw materials, etc., and these components are also treated as castor oil polyols. That is, the castor oil polyol used in the urethane-modified epoxy resin (A) of the present invention may be any one of these components used alone, or a combination of two or more of these components. In the present invention, a castor oil polyol having a hydroxyl equivalent of 150 to 1500 g / eq is used. The preferable hydroxyl equivalent is 400 to 1300 g / eq. When the hydroxyl equivalent is less than 150 g / eq, the crosslinking density of the urethane-modified epoxy resin (A) may increase and the toughness of the resulting cured product may be impaired. When the hydroxyl equivalent exceeds 1500 g / eq, the castor oil structure may aggregate and embrittle in the cured product. When two or more castor oil polyols are used in combination, it is preferable that the average value of the hydroxyl equivalent is within this range. In addition, the castor oil polyol preferably has an average functional group number of 1.5 to 2.7, and more preferably 1.8 to 2.3.

Chemical formula

[0019] Furthermore, among 100 parts by weight of the urethane-modified epoxy resin (A) used in the present invention, the ratio of the structure derived from polyisocyanate (polyisocyanate ratio) is 5 to 15 parts by weight, preferably 7 to 12 parts by weight. By the polyisocyanate ratio being within this range, a cured product excellent in toughness can be obtained while suppressing the gelation of the component (A). Here, the structure derived from polyisocyanate refers to the remaining structure excluding at least one isocyanate group (a part of the isocyanate group may be included) at the molecular terminal of the polyisocyanate which is a constituent component of the component (A).

[0020] As the polyisocyanate, known polyisocyanate compounds used in the production of polyurethane resins can be used. Specific examples of the polyisocyanate include aromatic diisocyanates such as toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures thereof (TDI), 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis(phenylene isocyanate) (MDI), crude or polymeric MDI, xylylene diisocyanate (XDI) and 1,5-naphthalene diisocyanate, aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate and 1,10-decamethylene diisocyanate, alicyclic diisocyanates such as 1,4-cyclohexylene diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate (IPDI) and hydrogenated XDI, and one or more polyisocyanate compounds selected from these can be used. The polyisocyanate may be used alone or in combination of two or more.

[0021] As a constituent of the urethane-modified epoxy resin (A), it is preferable to use a polyol (a) other than the castor oil polyol. Here, the polyol (a) other than the castor oil polyol is preferably in a ratio of the structure derived from the component (a) ((a) component ratio) of 0.4 to 4.0 parts by weight, more preferably 1.0 to 3.5 parts by weight, and even more preferably 2.0 to 3.0 parts by weight, based on 100 parts by weight of the component (A), and the hydroxyl equivalent of the component (a) is preferably 30 to 100 g / eq, more preferably 40 to 80 g / eq. When the ratio of the component (a) and the hydroxyl equivalent of the component (a) are within the above ranges, urethane bonds are incorporated at a high density in the resulting urethane-modified epoxy resin molecule, and hard segments in which urethane bonds aggregate by hydrogen bonding are formed in the cured product, thereby increasing the toughness and elastic modulus in the cured product, which is desirable. Here, the structure derived from the component (a) refers to the remaining structure excluding at least one hydroxyl group (which may include a part of the hydroxyl group) at the molecular end of the component (a) which is a constituent of the component (A).

[0022] As the polyol (a) other than the castor oil polyol, polyols having a hydroxyl equivalent of 30 to 100 g / eq such as ethylene glycol, propanediol, butanediol, pentanediol, methylpentanediol, hexanediol, nonanediol, decanediol, cyclohexanediol, resorcinol, catechol, hydroquinone, naphthalenediol, trimethylolpropane, glycerin, and pentaerythritol can be used. The polyol (a) may be used alone or in combination of two or more.

[0023] Of 100 parts by weight of the urethane-modified epoxy resin (A) used in the curable resin composition of the present invention, the ratio occupied by urethane bonds is preferably 3.0 to 10.0 parts by weight, more preferably 4.0 to 7.0 parts by weight. If it is less than 3.0 parts by weight, the elastic modulus and toughness when curing the resin composition tend to be insufficient. If it exceeds 10.0 parts by weight, the resin composition tends to have a high viscosity due to aggregation by hydrogen bonds caused by urethane bonds, which may impair the handleability during the curing reaction, and there may be adverse effects such as non-uniform cured products during curing.

[0024] Here, the ratio occupied by urethane bonds (urethane bond ratio) of the urethane-modified epoxy resin (A) used in the curable resin composition is determined by the following formula. Urethane bond ratio = 100×(weight of polyisocyanate used in the synthesis of urethane-modified epoxy resin × (47 / isocyanate equivalent of polyisocyanate used in the synthesis of urethane-modified epoxy resin)) / total weight of raw materials used in the synthesis of urethane-modified epoxy resin

[0025] The epoxy equivalent of the urethane-modified epoxy resin (A) used in the present invention is preferably 250 to 500 g / eq, more preferably 270 to 400 g / eq. Within this range, a cured product with high toughness can be obtained, and the elastic modulus of the cured product can also be increased. If the epoxy equivalent is less than 250 g / eq, the crosslinking density becomes high during curing, leading to a decrease in toughness. If it exceeds 500 g / eq, although the toughness can be increased, the elastic modulus of the cured product tends to decrease.

[0026] The urethane-modified epoxy resin (A) is obtained by heating and reacting at least an epoxy resin having a hydroxyl group in the molecule, a castor oil polyol having a hydroxyl group in the molecule, and a polyisocyanate. As the conditions for the heating reaction, known conditions can be appropriately adopted. The urethane-modified epoxy resin may contain an unmodified epoxy resin not bonded to the polyurethane.

[0027] The urethane-modified epoxy resin (A) is obtained by subjecting the constituent components to a heat reaction as described above. Although it is not restricted because it also depends on the manufacturing procedure, conditions, constituent components used, and their usage ratios, etc., it usually has the following molecular structure. That is, the polyol component [castor oil polyol and other polyols (a)], the polyisocyanate component, and any other optional components (for example, chain extender) react relatively preferentially to form a urethane bond to form polyurethane (which may be referred to as a urethane prepolymer). The hydroxyl group of the epoxy resin having a hydroxyl group in the molecule reacts with the isocyanate group thereof to form a structure having a urethane bond. Here, depending on the usage ratio and reaction conditions of each component when polyurethane is formed, etc., the structure (for example, chain length) and terminal structure (for example, functional group) of the obtained polyurethane can vary. When the epoxy resin reacts with it, a mixture is obtained in which the chain lengths of the structures derived from polyurethane are different, or the epoxy resin (structure derived from the epoxy resin) is added or not added to the terminals of those polyurethanes. Also, when an epoxy resin having no hydroxyl group is included, as described above, an unmodified epoxy resin not bonded to the polyurethane is included. Here, the structure derived from the epoxy resin refers to the remaining structure excluding at least one hydroxyl group (a part of the hydroxyl group may be included) of the epoxy resin. Thus, considering that the urethane-modified epoxy resin (A) of the present invention has a complex structure formed by the reaction of any or all of the constituent components, is obtained as a mixture thereof, and further, although it is considered not to be directly involved in the reaction or the expression of functions, it is difficult to completely distinguish or exclude the above-mentioned epoxy resin having no hydroxyl group (unmodified epoxy resin), etc., there are some circumstances (so-called impossible and impractical circumstances) such that it is impossible or not very practical to directly specify the component (A) by its structure or properties.

[0028] As the epoxy resin having a hydroxyl group in the molecule (hereinafter also referred to as the raw material epoxy resin), which is a raw material of the urethane-modified epoxy resin (A), known ones can be used without limitation, but bisphenol type epoxy resins having a hydroxyl group in the molecule are preferred. When this is used, the toughness can be increased without reducing the heat resistance of the cured product. The hydroxyl equivalent of the raw material epoxy resin is preferably 500 to 10,000 g / eq, more preferably 1,000 to 5,000 g / eq. When the hydroxyl equivalent is lower than 500 g / eq, the viscosity of the urethane-modified epoxy resin (A) tends to be high, and when it is higher than 10,000 g / eq, the toughness of the cured product tends to decrease. The epoxy equivalent of the raw material epoxy resin is preferably 100 to 300 g / eq, more preferably 160 to 260 g / eq.

[0029] Regarding the polyol (a) other than the castor oil polyol and the polyisocyanate (hereinafter also referred to as the raw material polyol (a) and the raw material polyisocyanate, respectively), which are raw materials of the urethane-modified epoxy resin (A), those listed above can be used, and various known ones can be used without particular limitation as long as the desired urethane-modified epoxy resin (A) can be obtained.

[0030] The blending amount of the urethane-modified epoxy resin (A) used in the curable resin composition of the present invention is preferably 15 to 50 parts by weight, more preferably 20 to 40 parts by weight, based on 100 parts by weight of the total amount of the components (A), (B), and (C). When it is less than 15 parts by weight, the toughness of the cured product when the resin composition is cured tends to decrease, and when it exceeds 50 parts by weight, the elastic modulus of the cured product tends to decrease.

[0031] As the non-urethane-modified epoxy resin (B) used in the present invention, an epoxy compound having two or more epoxy groups in one molecule and not being urethane-modified can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, bisphenol Z type epoxy resin, isophorone bisphenol type epoxy resin and other bisphenol type epoxy resins, or not limited to halogens, alkyl substituents, hydrogenated products, monomers of these bisphenols, but high molecular weight substances having a plurality of repeating units, glycidyl ethers of alkylene oxide adducts, phenol novolac type epoxy resins, cresol novolac type epoxy resins, bisphenol A novolac type epoxy resins and other novolac type epoxy resins, 3,4-epoxy-6-methylcyclohexylmethyl-3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 1-epoxyethyl-3,4-epoxycyclohexane and other alicyclic epoxy resins, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, polyoxyalkylene diglycidyl ether and other aliphatic epoxy resins, phthalic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, dimer acid glycidyl ester and other glycidyl esters, tetraglycidyl diaminodiphenylmethane, tetraglycidyl diaminodiphenyl sulfone, triglycidyl aminophenol, triglycidyl aminocresol, tetraglycidyl xylylenediamine and other glycidyl amines and the like can be used. Among these epoxy resins, bisphenol A type epoxy resin and bisphenol F type epoxy resin are excellent in economic efficiency, have good handleability because of their low viscosity as a resin composition, and are not likely to cause a factor for reducing heat resistance during curing, so they are preferably used. These may be used alone or in combination of two or more kinds.

[0032] The compounding amount of the non-urethane-modified epoxy resin (B) used in the curable resin composition of the present invention is preferably 30 to 80 parts by weight, more preferably 40 to 70 parts by weight, based on 100 parts by weight of the total amount of components (A), (B), and (C).

[0033] As the curing agent (C) used in the present invention, a compound that causes the curing reaction to proceed by reacting with the epoxy groups of components (A) and (B) by heating is applied, and two or more types of curing agents may be used. Examples of component (C) include phenolic resins, amine compounds, guanidine compounds, urea compounds, acid anhydrides, cyanate compounds, active ester compounds, and the like.

[0034] As the curing agent (C), an amine compound, dicyandiamide, and / or a derivative of dicyandiamide that is liquid at 25°C is particularly preferably used because it can increase the elastic modulus, toughness, and heat resistance.

[0035] Examples of amine compounds that are liquid at 25°C include aliphatic amines such as ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, hexamethylenetetramine, triethyleneglycol diamine, tetraethyleneglycol diamine, trimethylolpropane (oxypropylene) triamine, polyoxypropylene diamine, polyoxypropylene triamine, etc.; alicyclic amines such as 1,4-diazabicyclo-[2.2.2]-octane, 1,8-diazabicyclo-[5.4.0]-undec-7-ene, N,N'-dimethylpiperazine, N-aminoethylpiperazine, menthylenediamine, isophoronediamine, methylenebis(cyclohexanamine), 1,3-bis(aminomethyl)cyclohexane, norbornenediamine, 1,2-diaminocyclohexane, etc.; aromatic amines such as tetrachloro-p-xylenediamine, m-xylenediamine, p-xylenediamine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 2,4-toluenediamine, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, diethyltoluenediamine, methylbenzylamine, bis(methylthio)toluenediamine, 4,4'-methylenebis(N-sec-butylaniline), etc.; and modified alicyclic polyamines obtained by epoxy modification, ethylene oxide modification, dimer acid modification, Mannich modification, Michael addition, thiourea condensation, ketimine formation, etc. of these amine compounds. Among these, alicyclic amines or aromatic amines are preferably used in terms of enhancing toughness and heat resistance.

[0036] The blending amount of the amine compound that is liquid at 25°C is preferably 0.8 equivalent or more and 1.2 equivalents or less with respect to 1 equivalent of the total epoxy groups of the urethane-modified epoxy resin (A) and the non-urethane-modified epoxy resin (B) in terms of the active hydrogen group equivalent of the amine compound. When the equivalent ratio is less than 0.8 equivalent, the heat resistance tends to decrease, and when it exceeds 1.2 equivalents, the water absorption rate increases after curing, and the stability of the cured product tends to be impaired.

[0037] In the curable resin composition of the present invention, dicyandiamide or its derivative is preferably used as the curing agent (C). Dicyandiamide is a curing agent that is solid at room temperature and hardly dissolves in the epoxy resin at room temperature. However, it dissolves when heated to 180 °C or higher and has the property of reacting with epoxy groups, making it a latent curing agent with excellent storage stability at room temperature. As its derivative, N-substituted dicyandiamide derivatives such as N-hexyldicyandiamide described in JP-A-11-119429 can be used.

[0038] The blending amount of dicyandiamide or its derivative is preferably 0.3 equivalent or more and 0.8 equivalent or less based on 1 equivalent of the total epoxy groups of the urethane-modified epoxy resin (A) and the non-urethane-modified epoxy resin (B) in terms of the active hydrogen group equivalent. When the equivalent ratio is less than 0.3 equivalent, poor curing or a decrease in toughness is likely to occur, and when it exceeds 0.8 equivalent, the heat resistance tends to decrease.

[0039] In the curable resin composition of the present invention, an aromatic urea compound, an imidazole compound, or a phosphorus-based compound may be used as a curing aid to adjust the reactivity of dicyandiamide or its derivative.

[0040] The content of the aromatic urea compound as a curing aid contained in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 45 to 90 parts by weight, based on 100 parts by weight of the amount of dicyandiamide or its derivative. When the aromatic urea compound is contained within this range, a molded product excellent in curability in a short time and having high heat resistance during heat curing can be obtained.

[0041] Examples of the aromatic urea compound include 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, N-phenyl-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(3,4-dichlorophenyl)-N',N'-dimethylurea, N-(3-chloro-4-methylphenyl)-N',N'-dimethylurea, N-(3-chloro-4-ethylphenyl)-N',N'-dimethylurea, N-(3-chloro-4-methoxyphenyl)-N',N'-dimethylurea, N-(4-methyl-3-nitrophenyl)-N',N'-dimethylurea, 2,4-bis(N',N'-dimethylureido)toluene, methylene-bis(p-N',N'-dimethylureidophenyl), etc. Among these, 3-(3,4-dichlorophenyl)-1,1-dimethylurea and 3-(3,4-dichlorophenyl)-1,1-dimethylurea are preferred. These may be used alone or in combination of two or more, and are not limited to the above.

[0042] The content of the imidazole-based curing aid contained in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 40 to 80 parts by weight, based on 100 parts by weight of the amount of dicyandiamide or its derivative. When the imidazole-based curing aid is contained within this range, a molded article excellent in curability in a short time and having high heat resistance during heat curing can be obtained.

[0043] As an imidazole-based curing aid, in order to more satisfactorily achieve rapid curability during heat curing and heat resistance during curing in the present invention, it is preferable to use one or more imidazole compounds selected from the group consisting of 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-6-4',5'-dihydroxymethylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-S-triazine isocyanuric acid adduct, etc.

[0044] The content of the phosphorus-based curing aid contained in the curable resin composition of the present invention is preferably 5 to 100 parts by weight, more preferably 40 to 80 parts by weight, based on 100 parts by weight of the amount of dicyandiamide or its derivative. When the phosphorus-based curing aid is contained within this range, a molded article excellent in curability in a short time and having high heat resistance during heat curing can be obtained.

[0045] As a phosphorus-based curing aid, in order to better satisfy the fast curing property during heat curing and the heat resistance during curing in the present invention, tetrabutylphosphonium bromide, tetrabutylphosphonium chloride, tetrabutylphosphonium acetate, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, propyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, benzyltriphenylphosphonium chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakis(p-tolyl)borate, triphenylethylphosphonium tetraphenylborate, tris(3-methylphenyl)ethylphosphonium tetraphenylborate, tris(2-methoxyphenyl)ethylphosphonium tetraphenylborate, (4-methylphenyl)triphenylphosphonium thiocyanate, triphenylphosphine, tributylphosphine, tri-tert-butylphosphine, trioctylphosphine, di-tert-butyl(3-methyl-2-butenyl)phosphine, dibutylphenylphosphine, di-tert-butylphenylphosphine, methyldiphenylphosphine, ethyldiphenylphosphine, butyldiphenylphosphine, diphenylcyclohexylphosphine, triphenylphosphine, tri-o-tolylphosphine, tri-m-tolylphosphine, tri-p-tolylphosphine, tris(4-ethylphenyl)phosphine, tris(4-propylphenyl)phosphine, tris(4-isopropylphenyl)phosphine, tris(4-butylphenyl)phosphine, tris(4-tert-butylphenyl)phosphine, tris(2,4-dimethylphenyl)phosphine, tris(2,5-dimethylphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(3,5-dimethylphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, tris(2,It is preferable to use one or more phosphorus compounds selected from the group consisting of (6-dimethyl-4-ethoxyphenyl)phosphine, tris(2-methoxyphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(4-ethoxyphenyl)phosphine, tris(4-tert-butoxyphenyl)phosphine, diphenyl-2-pyridylphosphine, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,4-bis(diphenylphosphino)butane, and 2,2'-bis(diphenylphosphino)diphenyl ether.,

[0046] In addition, other curable resins can be added and blended with the curable resin composition of the present invention. Examples of such curable resins include, but are not limited to, unsaturated polyester resins, curable acrylic resins, curable amino resins, curable melamine resins, curable urea resins, curable cyanate ester resins, curable urethane resins, curable oxetane resins, curable epoxy / oxetane composite resins, and the like.,

[0047] The curable resin composition of the present invention is produced by uniformly mixing at least the above components (A), (B), and (C).

[0048] The molded article of the present invention is obtained by subjecting the above-described curable resin composition to a curing reaction. As a method for obtaining the molded article, it may conform to a general curing method for curable resin compositions. For example, the heating temperature conditions may be appropriately selected depending on the type and use of the curing agent to be combined. For example, a method of heating the curable resin composition in a temperature range of room temperature to about 250°C for 0.5 to 6.0 hours can be mentioned. General methods for curable resin compositions can also be used for the molding method and the like.,

[0049] According to the curable resin composition of the present invention, by including components derived from natural products in the constituent components of the urethane-modified epoxy resin (A) used, in addition to reducing the environmental load, by setting the structures derived from each constituent component to an appropriate ratio, a molded article can be obtained that exhibits strength and heat resistance equal to or higher than those of conventional curable epoxy resin compositions without reducing the heat resistance.

Examples

[0050] Next, the present invention will be specifically described based on examples. However, the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Parts indicating the blending amounts are parts by weight unless otherwise specified. Also, the unit of equivalent weight is g / eq.

[0051] The abbreviations of each component used in the examples are as follows.

[0052] 〔Non-urethane-modified epoxy resin (B)〕 YD-128: Bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 187 g / q) YDF-170: Bisphenol F type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd., epoxy equivalent 168 g / q)

[0053] 〔Castor oil polyol〕 CO1: Castor oil polyol with an average functionality of 2 and a hydroxyl equivalent of 630 g / eq (URIC HF-1300, manufactured by Ito Seiyu Co., Ltd.) CO2: Castor oil polyol with an average functionality of 2 and a hydroxyl equivalent of 1296 g / eq (URIC HF-2009, manufactured by Ito Seiyu Co., Ltd.)

[0054] 〔Polyol (a) other than castor oil polyol〕 BD: 1,4-Butanediol, hydroxyl equivalent 45 g / eq

[0055] 〔Polyisocyanate〕 TDI: Toluene diisocyanate MDI: Diphenylmethane diisocyanate

[0056] [Hardener (C)] BAC: 1,3 - bis(aminomethyl)cyclohexane (active hydrogen equivalent 36 g / eq) DICY: Dicyandiamide (active hydrogen equivalent 21 g / eq)

[0057] [Hardening Aid] (Aromatic Urea) DCMU: 3-(3,4 - dichlorophenyl)-1,1 - dimethylurea (Imidazole) MZA: 2,4 - diamino - 6 - [2’ - methylimidazolyl-(1’)] - ethyl - s - triazine

[0058] Synthesis Example 1 136 parts of YD - 128 and 45.1 parts of CO1 were charged into a glass separable flask equipped with a stirrer, thermometer, reflux tube, nitrogen gas introduction device, and charging port, and the temperature was raised to 110 °C while stirring. Next, 23.1 parts of TDI were added through the charging port, and after 1 hour had passed, 5.2 parts of BD were charged. The reaction temperature was further maintained at 130 °C for 2 hours of reaction to obtain 201 parts of a urethane - modified epoxy resin with a weight - average molecular weight Mw of 17,900, a castor oil polyol ratio of 22 wt%, a polyisocyanate ratio of 11 wt%, and an epoxy equivalent of 290 g / eq. This urethane - modified epoxy resin (A) component is designated as EPU1.

[0059] Synthesis Example 2 141 parts of YD - 128 and 78.2 parts of CO2 were charged into a device similar to that in Synthesis Example 1, and the temperature was raised to 110 °C while stirring. Next, 24.4 parts of TDI were added through the charging port, and after 1 hour had passed, 5.9 parts of BD were charged. The reaction temperature was further maintained at 130 °C for 2 hours of reaction to obtain 244 parts of a urethane - modified epoxy resin with a weight - average molecular weight Mw of 53,700, a castor oil polyol ratio of 31 wt%, a polyisocyanate ratio of 10 wt%, and an epoxy equivalent of 335 g / eq. This urethane - modified epoxy resin (A) component is designated as EPU2.

[0060] Synthesis Example 3 Into the same apparatus as in Synthesis Example 1, 117 parts of YDF-170 and 74.0 parts of CO2 were charged, and the temperature was raised to 110 °C while stirring. Next, 25.6 parts of MDI were added through the charging port, and after 1 hour had passed, 6.5 parts of BD were charged. The reaction temperature was further maintained at 130 °C and the reaction was carried out for 2 hours to obtain 219 parts of a urethane-modified epoxy resin having a weight average molecular weight Mw of 48,700, a castor oil polyol ratio of 33% by weight, a polyisocyanate ratio of 12% by weight, and an epoxy equivalent of 320 g / eq. This urethane-modified epoxy resin (A) component is designated as EPU3.

[0061] Synthesis Example 4 Into the same apparatus as in Synthesis Example 1, 189 parts of YD-128 and 25.7 parts of CO1 were charged, and the temperature was raised to 110 °C while stirring. Next, 8.0 parts of MDI were added through the charging port, and after 1 hour had passed, 2.1 parts of BD were charged. The reaction temperature was further maintained at 130 °C and the reaction was carried out for 2 hours to obtain 220 parts of a urethane-modified epoxy resin having a weight average molecular weight Mw of 4,400, a castor oil polyol ratio of 11% by weight, a polyisocyanate ratio of 3.6% by weight, and an epoxy equivalent of 220 g / eq. This urethane-modified epoxy resin (A’) component is designated as EPU4.

[0062] Synthesis Example 5 Into the same apparatus as in Synthesis Example 1, 76.4 parts of YDF-170 and 118 parts of CO2 were charged, and the temperature was raised to 110 °C while stirring. Next, 21.9 parts of TDI were added through the charging port, and after 1 hour had passed, 1.6 parts of BD were charged. The reaction temperature was further maintained at 130 °C and the reaction was carried out for 2 hours to obtain 209 parts of a urethane-modified epoxy resin having a weight average molecular weight Mw of 55,500, a castor oil polyol ratio of 54% by weight, a polyisocyanate ratio of 10% by weight, and an epoxy equivalent of 478 g / eq. This urethane-modified epoxy resin (A’) component is designated as EPU5.

[0063] (Measurement of weight average molecular weight Mw) Using a gel permeation chromatography HLC-8420GPC manufactured by Tosoh Corporation, equipped in series with TSKgel G4000HXL, TSKgel G3000HXL, and TSKgel G2000HXL manufactured by Tosoh Corporation, the weight average molecular weight Mw of the urethane-modified epoxy resin (A) or (A') was measured. The column temperature was set at 40 °C, tetrahydrofuran was used as the eluent, the flow rate was 1 ml / min, and gel permeation chromatography measurement was performed using an RI (differential refractometer) detector. Only the peak of the n = 0 form of the epoxy resin used as the raw material was excluded, and the weight average molecular weight Mw was determined on a polystyrene basis by summing up all other peaks.

[0064] Example 1 (Production of curable resin composition) 40 parts of EPU1 obtained in Synthesis Example 1 as component (A), 47 parts of YD-128 as component (B), and 13.5 parts of BAC as component (C) were placed in a 150 mL plastic container and mixed using a vacuum mixer "Avatori Rentaro" (trade name; manufactured by Shinki Co., Ltd.) while stirring at room temperature for 5 minutes to obtain a curable resin composition.

[0065] (Measurement of flexural modulus and flexural strength) The curable resin composition was poured into a mold measuring 60 mm in length × 240 mm in width with a 4 mm thick spacer cut out in a flat plate shape, cured at 140 °C for 4 hours to obtain a molded plate for measurement, and used for the measurement of flexural modulus and flexural strength. The obtained molded plate was cut into a size of 80 mm × 10 mm using a table band saw, and a flexural test was performed on the flexural test piece under a temperature condition of 23 °C using a universal material testing machine (Autograph AGS-H manufactured by Shimadzu Corporation) according to the method compliant with JIS 7171, and the flexural modulus and flexural strength were calculated.

[0066] (Measurement of fracture toughness) The curable resin composition was poured into a mold measuring 60 mm in length × 240 mm in width with a 2 mm thick spacer cut out in a flat plate shape, cured at 140 °C for 4 hours to obtain a molded plate for measurement, and used for the measurement of fracture toughness. The obtained molded plate was cut into a size of 50 mm × 10 mm using a desktop band saw, a crack was introduced according to ASTM E399, and the fracture toughness was measured using a universal material testing machine (Autograph AGS-H manufactured by Shimadzu Corporation) under a temperature condition of 23°C.

[0067] (Preparation of Test Specimens for Glass Transition Temperature Measurement) The curable resin composition was poured into a mold measuring 80 mm in length × 80 mm in width provided with a 4-mm-thick spacer cut out in a flat plate shape, cured at 140°C for 4 hours, and then the obtained molded plate was cut into a size of 50 mm × 10 mm using a desktop band saw and used for the measurement of the glass transition temperature described below.

[0068] (Measurement of Glass Transition Temperature) The above-mentioned molded plate was cut into a size of 2.5 mm × 2.5 mm using a desktop band saw, and further polished to a thickness of approximately 0.8 mm using a belt disk sander. Using a differential scanning calorimeter (DSC7000X manufactured by Hitachi High-Tech Science Corporation), the measurement was carried out under a nitrogen atmosphere at a heating rate of 10°C / min. The intersection point between the tangent line at the inflection point of the DSC curve and the tangent line in the temperature region that is 15 to 30°C lower than the temperature at which the start of the inflection is observed, that is, the temperature at the inflection point, was obtained, and that temperature was defined as the glass transition temperature Tg.

[0069] The test results of Examples 1 to 11 and Comparative Examples 1 to 5 are shown in Table 1 and Table 2, respectively.

[0070]

Table 1

[0071]

Table 2

Industrial Applicability

[0072] The molded article obtained by curing using the curable resin composition of the present invention can be preferably used for applications that require heat resistance and toughness while reducing the environmental load by applying a plant-derived raw material.

Claims

1. A curable resin composition comprising urethane-modified epoxy resin (A), non-urethane-modified epoxy resin (B) and a curing agent (C) as essential components, wherein the urethane-modified epoxy resin (A) has a structure derived from castor oil polyol and a structure derived from polyisocyanate, in 100 parts by weight of the urethane-modified epoxy resin (A), the ratio of the structure derived from castor oil polyol is 15 to 50 parts by weight, and the ratio of the structure derived from polyisocyanate is 5 to 15 parts by weight, and the hydroxyl equivalent of the castor oil polyol is 150 to 1500 g / eq. The curable resin composition is characterized by this.

2. The urethane-modified epoxy resin (A) has a structure derived from a polyol (a) other than castor oil polyol. In 100 parts by weight of the urethane-modified epoxy resin (A), the ratio of the structure derived from the component (a) is 0.4 to 4.0 parts by weight, and the hydroxyl equivalent of the component (a) is 30 to 100 g / eq. The curable resin composition according to Claim 1 is characterized by this.

3. In 100 parts by weight of the urethane-modified epoxy resin (A), the weight ratio occupied by the urethane bond is 3.0 to 10.0 parts by weight. The curable resin composition according to Claim 1 is characterized by this.

4. The epoxy equivalent of the urethane-modified epoxy resin (A) is 250 to 500 g / eq. The curable resin composition according to Claim 1 is characterized by this.

5. The curing agent (C) is one or more selected from the group consisting of amines, dicyandiamide and derivatives of dicyandiamide that are liquid at 25°C. The curable resin composition according to Claim 1 is characterized by this.

6. A molded article characterized by curing the curable resin composition according to any one of Claims 1 to 5.

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