POLYURETHANE-MODIFIED EPOXY RESIN, METHOD FOR PRODUCING SAME, EPOXY RESIN COMPOSITION AND CURED PRODUCT

Abstract

Provided are a polyurethane-modified epoxy resin composition having satisfactory operability of processing, such as casting or impregnation, in a composition state, a production method therefor, and a composition thereof. The polyurethane-modified epoxy resin is obtained by modifying a secondary hydroxyl group-containing bisphenol-based epoxy resin (a) having an epoxy equivalent of from 150 g/eq to 200 g/eq and a hydroxyl equivalent of from 2,000 g/eq to 2,600 g/eq with a medium to high molecular weight polyol compound (b) having an Mn of 200 or more, a polyisocyanate compound (c), and a low molecular weight polyol compound (d) having an Mn of less than 200 serving as a chain extender. The polyurethane-modified epoxy resin uses the epoxy resin (a) in an amount of from 20 wt % to 60 wt % with respect to the total amount of the respective components (a), (b), (c), and (d), and contains a polyurethane having the epoxy resin (a) added to each of both terminals thereof and/or one terminal thereof.

Claims

1-8. (canceled)

9. A polyurethane-modified epoxy resin, which is obtained by modifying a bisphenol-based epoxy resin (a) represented by the following formula (1) having an epoxy equivalent of from 150 g/eq to 200 g/eq and a hydroxyl equivalent of from 2,000 g/eq to 2,600 g/eq with a medium to high molecular weight polyol compound (b) having a number-average molecular weight of 200 or more, a polyisocyanate compound (c), and a low molecular weight polyol compound (d) having a number-average molecular weight of less than 200 serving as a chain extender, the polyurethane-modified epoxy resin comprising a polyurethane having the epoxy resin (a) added to each of both terminals thereof and/or one terminal thereof, the polyurethane being obtained by: producing a urethane prepolymer (P) by using the epoxy resin (a) in an amount of from 20 wt % to 40 wt % with respect to a total amount of the components (a), (b), (c), and (d), and causing the medium to high molecular weight polyol compound (b) and the polyisocyanate compound (c) to react with each other in a presence of the epoxy resin (a) while using the compounds in such amounts that a molar ratio between primary OH groups of the component (b) and NCO groups of the component (c) falls within a range of from 1:1.5 to 1:3; and then subjecting the urethane prepolymer (P) to a polyurethanation reaction by adding the low molecular weight polyol compound (d) so that a molar ratio between NCO groups of the urethane prepolymer (P) and OH groups of the low molecular weight polyol compound (d) may fall within a range of from 0.9:1 to 1:0.9: ##STR00021## where R and R.sub.1 each represent H or a methyl group, and a represents a number of from 0 to 10.

10. A polyurethane-modified epoxy resin according to claim 9, wherein the medium to high molecular weight polyol compound (b) comprises a compound represented by any one of the following formulae (2), (4) to (7), (10), and (11), the polyisocyanate compound (c) comprises a compound represented by the following formula (12), and the low molecular weight polyol compound (d) comprises a compound represented by the following formula (13): ##STR00022## where R.sub.2 represents H or a methyl group, b1, b2, and b3 each independently represent a number of from 1 to 50, and c represents a number of 0 or 1; ##STR00023## where f's each independently represent a number of from 1 to 20, and g represents a number of from 1 to 50; ##STR00024## where h1 and h2 each independently represent a number of from 1 to 20, and i represents a number of from 1 to 50; ##STR00025## where j1, j2, and j3 each independently represent a number of from 1 to 20, and k1 and k2 each independently represent a number of from 1 to 50; ##STR00026## where l1, l2, l3, l4, and l5 each independently represent a number of from 1 to 20, and m1 and m2 each independently represent a number of from 1 to 50; ##STR00027## where q1, q2, q3, and q4 each independently represent a number of from 1 to 20; ##STR00028## where r, s, and t each independently represent a number of from 1 to 20, and n represents a number of from 1 to 50; ##STR00029## in the formula 12, R.sub.4 represents a divalent group selected from the formulae 12a to 12f; ##STR00030## in the formula 13, R.sub.5 represents an alkylene group represented by the formula 13a and g represents a number of from 1 to 10.

11. A polyurethane-modified epoxy resin according to claim 9 or 10, wherein the epoxy resin (a) comprises a bisphenol A-type epoxy resin represented by the following formula (14) or a bisphenol F-type epoxy resin represented by the following formula (15), the medium to high molecular weight polyol compound (b) comprises a polypropylene glycol represented by the following formula (16), the low molecular weight polyol compound (d) comprises 1,4-butanediol represented by the following formula (17), and the polyisocyanate compound (c) comprises 4,4-diphenylmethane diisocyanate represented by the following formula (18): ##STR00031## where a1 represents a number of from 0 to 10; ##STR00032## where a2 represents a number of from 0 to 10; ##STR00033## where b1 and b2 each independently represent a number of from 1 to 50. ##STR00034##

12. A method of producing the polyurethane-modified epoxy resin of claim 9, comprising: producing a urethane prepolymer (P) by using a bisphenol-based epoxy resin (a) represented by the following formula (1) having an epoxy equivalent of from 150 g/eq to 200 g/eq and a hydroxyl equivalent of from 2,000 g/eq to 2,600 g/eq in an amount of from 20 wt % to 40 wt % with respect to a total amount of the epoxy resin (a), a medium to high molecular weight polyol compound (b) having a number-average molecular weight of 200 or more, a polyisocyanate compound (c), and a low molecular weight polyol compound (d) having a number-average molecular weight of less than 200 serving as a chain extender, and causing the medium to high molecular weight polyol compound (b) and the polyisocyanate compound (c) to react with each other in a presence of the epoxy resin (a) while using the compounds in such amounts that a molar ratio between primary OH groups of the component (b) and NCO groups of the component (c) falls within a range of from 1:1.5 to 1:3; and then subjecting the urethane prepolymer (P) to a polyurethanation reaction by adding the low molecular weight polyol compound (d) so that a molar ratio between NCO groups of the urethane prepolymer (P) and OH groups of the low molecular weight polyol compound (d) may fall within a range of from 0.9:1 to 1:0.9: ##STR00035## where R and R.sub.1 each represent H or a methyl group, and a represents a number of from 0 to 10.

13. An epoxy resin composition, which is obtained by blending the polyurethane-modified epoxy resin of claim 9 with a polyurethane-unmodified epoxy resin (e), a curing agent (f), and a curing accelerator (g), wherein the composition has a weight concentration of polyurethane constituent components of from 10 wt % to 30 wt %.

14. An epoxy resin cured product, which is obtained by curing the epoxy resin composition of claim 13.

15. A polyurethane-modified epoxy resin according to claim 9, wherein the bisphenol-based epoxy resin (a) comprises a bisphenol A-type epoxy resin.

16. A method of producing the polyurethane-modified epoxy resin according to claim 12, wherein the bisphenol-based epoxy resin (a) comprises a bisphenol A-type epoxy resin.

Description

EXAMPLES

[0069] Next, the present invention is specifically described on the basis of Examples. Example 1 to Example 5 and Reference Example 1 to Reference Example 4 relate to polyurethane-modified epoxy resins, and Example 6 to Example 10 and Comparative Example 1 to Comparative Example 4 relate to compositions and cured products thereof. The present invention is not limited by the specific examples, and various changes and modifications can be performed as long as the changes and modifications do not deviate from the gist of the present invention.

[0070] Methods of evaluating characteristics described in Examples are as described below.

[0071] (1) Viscosity: The viscosity of each of polyurethane-modified epoxy resins described in Examples and Comparative Examples below at 120 C. was measured with an ICI viscometer. In addition, the viscosity of each resin composition before its curing at 25 C. was measured with an E-type viscometer.

[0072] (2) Judgement of Presence or Absence of Remaining NCO Group through IR: 0.05 g of the resultant polyurethane-modified epoxy resin was dissolved in 10 ml of tetrahydrofuran. After that, the solution was applied onto a KBr plate with a micro-spatula flat plate portion, and was dried at room temperature for 15 minutes so that tetrahydrofuran was evaporated. Thus, a sample for IR measurement was prepared. The sample was set in a FT-IR apparatus Spectrum-One manufactured by PerkinElmer Co., Ltd., and when a stretching vibration absorption spectrum at 2,270 cm.sup.1 serving as the characteristic absorption band of an NCO group disappeared, it was judged that no remaining NCO group was present.

[0073] (3) Epoxy Equivalent: Determination was performed in accordance with JIS K 7236.

[0074] (4) Hydroxyl Equivalent: 25 ml of dimethylformamide was loaded into a 200-milliliter Erlenmeyer flask with a glass plug, and a sample containing 11 mg/eq or less of a hydroxyl group was precisely weighed and added to dimethylformamide to be dissolved therein. 20 ml of a 1 mol/l solution of phenyl isocyanate in toluene and 1 ml of a saturated solution of dibutyltin maleate were each added to the solution with a pipette, and the contents were shaken well to be mixed. The flask was tightly sealed and the mixture was subjected to a reaction for from 30 minutes to 60 minutes. After the completion of the reaction, 20 ml of a 2 mol/l solution of dibutylamine in toluene was added to the resultant, and the contents were shaken well to be mixed. The mixture was left to stand for 15 minutes and caused to react with excess phenyl isocyanate. Next, 30 ml of methyl cellosolve and 0.5 ml of a bromcresol green indicator were added to the resultant, and an excess amine was titrated with a 1 mol/l solution of perchloric acid in methyl cellosolve that had already been standardized. The color of the indicator changed from a blue color to a green color and then to a yellow color, and hence the first point at which the color became a yellow color was defined as an end point, and a hydroxyl equivalent was determined by using the following equation i and equation ii.

Hydroxyl equivalent (g/eq)=(1,000W)/C(SB)(i)

C: concentration of 1 mol/l solution of perchloric acid in methyl cellosolve in mol/l
W: amount of sample (g)
S: titration amount of 1 mol/l solution of perchloric acid in methyl cellosolve required for titration of a sample (ml)
B: titration amount of 1 mol/l solution of perchloric acid in methyl cellosolve required for blank test during titration (ml)

C=(1,000W)/{121(sb)}(ii)

w: collection amount of tris-(hydroxymethyl)-aminomethane weighed for standardization (g)
s: titration amount of 1 mol/l solution of perchloric acid in methyl cellosolve required for titration of tris-(hydroxymethyl)-aminomethane (ml)
b: titration amount of 1 mol/l solution of perchloric acid in methyl cellosolve required for blank test during standardization (ml)

[0075] (5) Tensile Test: A cured product molded into the shape of JIS K 6911 by mold casting was used as a test piece, and its rupture elongation, rupture strength, and elastic modulus were each measured by performing a tensile test with a universal tester under a room temperature of 23 C. and under the condition of a crosshead speed of 5 mm/min.

[0076] (6) Fracture Toughness (K.sub.1c): Measurement was performed in accordance with the bending method of ASTM E-399 under a room temperature of 23 C. at a crosshead speed of 0.5 mm/min.

[0077] (7) Dynamic Viscoelasticity (DMA): The temperature dispersion storage modulus (E) and temperature dispersion loss tangent (tan ) of a cured product test piece molded into a rectangular parallelopiped shape measuring 4 mm by 10 mm by 50 mm by cast molding were measured with a dynamic viscoelasticity-measuring apparatus under the conditions of a frequency of 10 Hz and a rate of temperature increase of 2 C./min, and the E at each of 40 C. and 180 C. was calculated. Simultaneously, the glass transition temperature (Tg) thereof was derived from the peak temperature of a tan curve.

[0078] The following raw materials were used. [0079] Epoxy resin (a1): Epotohto YD-128 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol A-type epoxy resin, epoxy equivalent: 186 g/eq, hydroxyl equivalent: 2,272 g/eq [0080] Epoxy resin (a2): Epotohto YDF-170 manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., bisphenol F-type epoxy resin, epoxy equivalent=170 (g/eq), hydroxyl equivalent=2,489 (g/eq) [0081] Polyol (b); ADEKA POLYETHER P-2000 manufactured by ADEKA Corporation, polypropylene glycol, average molecular weight: 2,000, hydroxyl equivalent: 1,020 g/eq [0082] Polyisocyanate (c); COSMONATE PH manufactured by Mitsui Chemicals, Inc., 4,4-diphenylmethane diisocyanate [0083] Low molecular weight polyol (d) compound; 1,4-butanediol (reagent) [0084] Polyurethane-unmodified epoxy resin (e1): the same as epoxy resin (a1) [0085] Polyurethane-unmodified epoxy resin (e2): the same as epoxy resin (a2) [0086] Curing agent (f): HN-2200R manufactured by Hitachi Chemical Co., Ltd., methyltetrahydrophthalic anhydride [0087] Curing accelerator (g): Curezol 1B2MZ manufactured by Shikoku Chemicals Corporation, l-benzyl-2-methylimidazole

Example 1

Synthesis of Polyurethane-Modified Bisphenol A-Type Epoxy Resin I

[0088] 80.0 g of a bisphenol A-type epoxy resin Epotohto YD-128 serving as the epoxy resin (a1) and 249.4 g of a polypropylene glycol ADEKA POLYETHER P-2000 serving as the polyol compound (b) were each loaded into a 500-milliliter four-necked separable flask including a nitrogen-introducing tube, a stirring machine, and a temperature controller, and were stirred and mixed at room temperature for 15 minutes. Next, 61.1 g of 4,4-diphenylmethane diisocyanate COSMONATE PH serving as the polyisocyanate compound (c) was loaded into the separable flask, and the mixture was subjected to a reaction at 120 C. for 2 hr (reaction 1: urethane prepolymer step). After that, 9.4 g of 1,4-butanediol serving as the low molecular weight polyol compound (d) that was a chain extender was loaded into the separable flask, and the mixture was subjected to a reaction at 120 C. for 2 hr (reaction 2: polyurethane step) to provide 400 g of a polyurethane-modified bisphenol A-type epoxy resin I. In this case, the epoxy resin (a1) was loaded so that its amount became 20 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol A-type epoxy resin I had an epoxy equivalent of 936 g/eq and a viscosity at 120 C. of 11.5 Pa-s.

Example 2

Synthesis of Polyurethane-Modified Bisphenol A-Type Epoxy Resin II

[0089] 400 g of a polyurethane-modified bisphenol A-type epoxy resin II was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a1) was loaded so that its amount became 40 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol A-type epoxy resin II had an epoxy equivalent of 464 g/eq and a viscosity at 120 C. of 2.64 Pa.Math.s.

Reference Example 5

Synthesis of Polyurethane-Modified Bisphenol A-Type Epoxy Resin III

[0090] 400 g of a polyurethane-modified bisphenol A-type epoxy resin III was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a1) was loaded so that its amount became 60 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol A-type epoxy resin III had an epoxy equivalent of 312 g/eq and a viscosity at 120 C. of 0.45 Pa.Math.s.

Example 4

Synthesis of Polyurethane-Modified Bisphenol F-Type Epoxy Resin I

[0091] 400 g of a polyurethane-modified bisphenol F-type epoxy resin I was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a2) was loaded so that its amount became 40 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol F-type epoxy resin I had an epoxy equivalent of 416 g/eq and a viscosity at 120 C. of 1.44 Pa.Math.s.

Reference Example 6

Synthesis of Polyurethane-Modified Bisphenol F-Type Epoxy Resin II

[0092] 400 g of a polyurethane-modified bisphenol F-type epoxy resin II was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a2) was loaded so that its amount became 60 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol F-type epoxy resin II had an epoxy equivalent of 378 g/eq and a viscosity at 120 C. of 0.30 Pa.Math.s.

Reference Example 1

Synthesis of Polyurethane-Modified Bisphenol A-Type Epoxy Resin IV

[0093] 400 g of a polyurethane-modified bisphenol A-type epoxy resin IV was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a1) was loaded so that its amount became 10 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol A-type epoxy resin IV had an epoxy equivalent of 1,870 g/eq and a viscosity at 120 C. of 32.8 Pa.Math.s.

Reference Example 2

Synthesis of Polyurethane-Modified Bisphenol A-Type Epoxy Resin V

[0094] 400 g of a polyurethane-modified bisphenol A-type epoxy resin V having an epoxy resin concentration of 64 wt. % was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a1) was loaded so that its amount became 64 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol A-type epoxy resin V had an epoxy equivalent of 290 g/eq and a viscosity at 120 C. of 0.21 Pa-s.

Reference Example 3

Synthesis of Polyurethane-Modified Bisphenol F-Type Epoxy Resin III

[0095] 400 g of a polyurethane-modified bisphenol F-type epoxy resin III was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a2) was loaded so that its amount became 10 wt % with respect to 100 wt % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol F-type epoxy resin III had an epoxy equivalent of 1,680 g/eq and a viscosity at 120 C. of 34.4 Pa-s.

Reference Example 4

Synthesis of Polyurethane-Modified Bisphenol F-Type Epoxy Resin IV

[0096] 400 g of a polyurethane-modified bisphenol F-type epoxy resin IV having an epoxy resin concentration of 66 wt. % was obtained by performing reactions in accordance with the same procedure as that of Example 1 except that raw material loading composition was changed as shown in Table 1. In this case, the epoxy resin (a2) was loaded so that its amount became 66 wt % with respect to 100 wL % of the product of the reaction 2. The completion of the reactions was confirmed by the disappearance of the absorption spectrum of an NCO group through IR measurement. The resultant polyurethane-modified bisphenol F-type epoxy resin IV had an epoxy equivalent of 257 g/eq and a viscosity at 120 C. of 0.17 Pa-s.

TABLE-US-00001 TABLE 1 Reference Reference Example 1 Example 2 Example 5 Example 4 Example 6 Epoxy resin (a1) 80.0 (20.0) 160.0 (40.0) 240.0 (60.0) 0 (0) 0 (0) Epoxy resin (a2) 0 (0) 0 (0) 0 (0) 160.0 (40.0) 240 (60.0) Polyol compound 249.4 (62.4) 188.6 (47.2) 127.8 (32.0) 188.4 (47.1) 127.5 (31.9) (b) Polyisocyanate 61.1 (15.3) 46.2 (11.6) 31.3 (7.8) 46.2 (11.5) 31.2 (7.8) compound (c) Low molecular 9.4 (2.4) 5.2 (1.3) 0.9 (0.2) 5.4 (1.4) 1.3 (0.3) weight polyol compound (d) Total [g] 400 (100) 400 (100) 400 (100) 400 (100) 400 (100) (wt %) Concentration 20 40 60 40 60 of epoxy resin (a) (wt %) Remaining None None None None None NCO group Reference Reference Reference Reference Example 1 Example 2 Example 3 Example 4 Epoxy resin (a1) 40.0 (10.0) 256.6 (64.1) 0 (0) 0 (0) Epoxy resin (a2) 0 (0) 0 (0) 40.0 (10.0) 264.9 (66.2) Polyol compound 279.9 (70.0) 115.2 (28.8) 279.8 (70.0) 108.5 (27.1) (b) Polyisocyanate 68.6 (17.2) 28.2 (7.1) 68.6 (17.1) 26.6 (6.7) compound (c) Low molecular 11.6 (2.9) 0 (0) 11.6 (2.9) 0 (0) weight polyol compound (d) Total [g] 400 (100) 400 (100) 400 (100) 400 (100) (wt %) Concentration 10 64 10 66 of epoxy resin (a) (wt %) Remaining None None None None NCO group (Remark) In the table, a numerical value in parentheses ( ) represents a wt %.

[0097] Next, Examples of epoxy resin compositions and epoxy resin cured products using the polyurethane-modified epoxy resins of Examples 1 to 5 and Reference Examples described above are described. Simultaneously, their results are collectively shown in Table 2.

Example 6

[0098] 26.0 g of the polyurethane-modified bisphenol A-type epoxy resin I obtained in Example 1 serving as a polyurethane-modified epoxy resin, 52.3 g of Epotohto YD-128 serving as the polyurethane-unmodified epoxy resin (e), 51.0 g of HN-2200R serving as the curing agent (f), and 0.7 g of 1B2MZ serving as the curing accelerator (g) were each loaded into a 500-milliliter disposable cup, and were stirred and mixed well with a stainless-steel spatula to provide a liquid resin composition. In this case, a molar ratio between an epoxy group and a carboxylic anhydride group was set to 1:1, and 130 g of a polyurethane-modified bisphenol A-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 10 wt % was prepared. The composition thus blended and prepared was then heated in a hot air oven at 80 C. for 15 minutes in order for the escape of bubbles to be promoted. After that, the composition was loaded into a vacuum desiccator and subjected to vacuum defoaming for 1.5 hr. The resultant liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 34 Pa.Math.s.

[0099] Next, the liquid resin composition that had already been defoamed was cast into each of: a mold having 5 groove shapes each having the dimensions of a test piece for a tensile test of JIS K 6911; and molds for a fracture toughness test and for a DMA test each having 6 groove shapes each measuring 100 mm long by 4 mm wide by 5 mm high. A casting property at this time was at such a level that the composition was able to be sufficiently cast with a margin. Next, a mold having cast thereinto the resin was loaded into a hot air oven, and was thermally cured at 80 C. for 2 hr and then at 100 C. for 3 hr to prepare an epoxy resin cured product test piece. The test piece was subjected to a tensile test and a fracture toughness test under the conditions described in the foregoing. As a result, the test piece had a rupture elongation of 7.0% and a fracture toughness of 1.80 MPa.Math.m.sup.0.5, and hence the cured product was extremely useful as, for example, a resin for a leading-edge composite material required to have a high fatigue resistance characteristic. In addition, the glass transition temperature of the cured product by the DMA measurement was 126 C., and hence the cured product simultaneously achieved a rupture elongation as high as 5% or more, a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, and high heat resistance, specifically a glass transition temperature of 110 C. or more.

Example 7

[0100] 130 g of a polyurethane-modified bisphenol A-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 20 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol A-type epoxy resin II obtained in Example 2 serving as a polyurethane-modified epoxy resin, the polyurethane-unmodified epoxy resin (e), the curing agent (f), and the curing accelerator (g) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 54 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 11.2% and a fracture toughness of 1.62 MPa.Math.m.sup.0.5, and hence the cured product was also extremely useful as, for example, a resin for a leading-edge composite material required to have a high fatigue resistance characteristic. In addition, the glass transition temperature of the cured product by the DMA measurement was 123 C., and hence the cured product simultaneously achieved a rupture elongation as high as 5% or more, a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, and high heat resistance, specifically a glass transition temperature of 110 C. or more.

Example 8

[0101] 130 g of a polyurethane-modified bisphenol A-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 30 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol A-type epoxy resin III obtained in Example 3 serving as a polyurethane-modified epoxy resin, the polyurethane-unmodified epoxy resin (e), the curing agent (f), and the curing accelerator (g) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 54 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 6.5% and a fracture toughness of 1.26 MPa.Math.m.sup.0.5, and hence the cured product was also extremely useful as, for example, a resin for a leading-edge composite material required to have a high fatigue resistance characteristic. In addition, the glass transition temperature of the cured product by the DMA measurement was 120 C., and hence the cured product simultaneously achieved a rupture elongation as high as 5% or more, a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, and high heat resistance, specifically a glass transition temperature of 110 C. or more.

Example 9

[0102] 130 g of a polyurethane-modified bisphenol F-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 20 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol F-type epoxy resin I obtained in Example 4 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 18 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 8.9% and a fracture toughness of 1.39 MPa.Math.s.sup.0.5, and hence the cured product was also extremely useful as, for example, a resin for a leading-edge composite material required to have a high fatigue resistance characteristic. In addition, the glass transition temperature of the cured product by the DMA measurement was 120 C., and hence the cured product simultaneously achieved a rupture elongation as high as 5% or more, a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, and high heat resistance, specifically a glass transition temperature of 110 C. or more.

Example 10

[0103] 130 g of a polyurethane-modified bisphenol F-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 30 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol F-type epoxy resin II obtained in Example 5 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 12 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 5.2% and a fracture toughness of 1.20 MPa.Math.m.sup.0.5, and hence the cured product was also extremely useful as, for example, a resin for a leading-edge composite material required to have a high fatigue resistance characteristic. In addition, the glass transition temperature of the cured product by the DMA measurement was 120 C., and hence the cured product simultaneously achieved a rupture elongation as high as 5% or more, a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, and high heat resistance, specifically a glass transition temperature of 110 C. or more.

Comparative Example 1

[0104] 130 g of a polyurethane-modified bisphenol A-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 5 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol A-type epoxy resin IV obtained in Reference Example 1 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 12 Pa-s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 2.4%, a fracture toughness of 1.20 MPa.Math.s.sup.0.5, and a glass transition temperature of 129 C. Although the test piece showed a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more and high heat resistance, specifically a glass transition temperature of 110 C. or more, the rupture elongation was 5% or less, and hence the three characteristics could not be achieved simultaneously.

Comparative Example 2

[0105] 130 g of a polyurethane-modified bisphenol A-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 32 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol A-type epoxy resin V obtained in Reference Example 2 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 21 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 4.3%, a fracture toughness of 1.10 MPa.Math.m.sup.0.5, and a glass transition temperature of 111 C. Although the test piece showed a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more and high heat resistance, specifically a glass transition temperature of 110 C. or more, the rupture elongation was 5% or less, and hence the three characteristics could not be achieved simultaneously.

Comparative Example 3

[0106] 130 g of a polyurethane-modified bisphenol F-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 5 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol F-type epoxy resin III obtained in Reference Example 3 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 3 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 1.1%, a fracture toughness of 0.52 MPa.Math.m.sup.0.5, and a glass transition temperature of 125 C. Although the test piece showed high heat resistance, specifically a glass transition temperature of 110 C. or more, the test piece could not show a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more and a rupture elongation of 5% or more.

Comparative Example 4

[0107] 130 g of a polyurethane-modified bisphenol F-type epoxy resin composition having a polyurethane concentration in a cured product thereof of 5 wt % was prepared in accordance with the same procedure as that of Example 6 except that the polyurethane-modified bisphenol F-type epoxy resin IV obtained in Reference Example 4 serving as a polyurethane-modified epoxy resin, an epoxy resin (for dilution), an acid anhydride (the curing agent), and imidazole (the curing accelerator) were used according to blending composition shown in Table 2. Next, a defoamed liquid resin composition was obtained by performing a defoaming operation in accordance with the same procedure as that of Example 6. The liquid resin composition that had already been subjected to the defoaming operation had a viscosity at 25 C. of 7 Pa.Math.s. Next, in accordance with the same procedure as that of Example 6, the defoamed liquid resin composition was cast into a mold and thermally cured to prepare a test piece for a characteristic evaluation. Next, a tensile test, DMA measurement, and a fracture toughness test were performed under the same conditions as those of Example 6. As a result, the test piece had a rupture elongation of 4.6%, a fracture toughness of 1.11 MPa.Math.m.sup.0.5, and a glass transition temperature of 106 C. Although the test piece showed a fracture toughness as high as 1.1 MPa.Math.m.sup.0.5 or more, the test piece could not show a rupture elongation of 5% or more and a glass transition temperature of 110 C. or more.

TABLE-US-00002 TABLE 2 Reference Reference Example 6 Example 7 Example 7 Example 9 Example 8 Composition Polyurethane- Example 1 26.0 (20.0) 0 (0) 0 (0) 0 (0) 0 (0) modified (BPA-type) epoxy Example 2 0 (0) 52.0 (40.0) 0 (0) 0 (0) 0 (0) resin (BPA-type) Reference 0 (0) 0 (0) 78.0 (60.0) 0 (0) 0 (0) Example 5 (BPA-type) Example 4 0 (0) 0 (0) 0 (0) 52.0 (40.0) 0 (0) (BPF-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) 78.0 (60.0) Example 6 (BPF-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Example 1 (BPA-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Example 2 (BPA-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Example 3 (BPF-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) 0 (0) Example 4 (BPF-type) Polyurethane- BPA-type 52.3 (40.2) 31.1 (24.0) 5.2 (4.0) 0 (0) 0 (0) unmodified BPF-type 0 (0) 0 (0) 0 (0) 28.6 (22.0) 2.4 (1.9) epoxy resin (e) Curing agent (f) 51.0 (39.3) 46.2 (35.5) 46.1 (35.5) 48.7 (37.5) 48.9 (37.6) Curing accelerator (g) 0.7 (0.5) 0.7 (0.5) 3.7 (3.5) 0.7 (0.5) 0.7 (0.5) Total (g) [(wt %)] 130 (100) 130 (100) 130 (100) 130 (100) 130 (100) Polyurethane component 16 24 24 24 24 concentration (wt %) Viscosity of composition (Pa .Math. s) 34 54 24 18 12 Cured product Rupture elongation (%) 7.0 11.2 6.5 8.9 5.2 characteristic Elastic modulus (GPa) 2.2 1.6 1.7 1.5 1.6 Rupture strength (MPa) 45.1 37.8 41.4 37.2 37.8 Tg ( C.) 126 123 120 120 111 Storage Measurement at 1.1 0.8 0.9 0.7 1.1 modulus 40 C. (GPa) E Measurement at 17.8 13.2 11.7 15.0 14.8 170 C. (MPa) Fracture toughness K.sub.1C 1.80 1.62 1.26 1.39 1.20 (MPa .Math. m.sup.0.5) Reference Reference Reference Reference Example 1 Example 2 Example 3 Example 4 Composition Polyurethane- Example 1 0 (0) 0 (0) 0 (0) 0 (0) modified (BPA-type) epoxy Example 2 0 (0) 0 (0) 0 (0) 0 (0) resin (BPA-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) Example 5 (BPA-type) Example 4 0 (0) 0 (0) 0 (0) 0 (0) (BPF-type) Reference 0 (0) 0 (0) 0 (0) 0 (0) Example 6 (BPF-type) Reference 13.0 (10.0) 0 (0) 0 (0) 0 (0) Example 1 (BPA-type) Reference 0 (0) 82.3 (63.3) 0 (0) 0 (0) Example 2 (BPA-type) Reference 0 (0) 0 (0) 13.0 (10.0) 0 (0) Example 3 (BPF-type) Reference 0 (0) 0 (0) 0 (0) 78.6 (60.5) Example 4 (BPF-type) Polyurethane- BPA-type 55.3 (42.6) 0 (0) 0 (0) 0 (0) unmodified BPF-type 0 (0) 0 (0) 58.2 (44.8) 0 (0) epoxy resin (e) Curing agent (f) 55.3 (42.6) 47.1 (36.2) 58.1 (44.7) 50.8 (39.0) Curing accelerator (g) 3.7 (3.5) 0.7 (0.5) 3.7 (3.5) 0.7 (0.5) Total (g) [(wt %)] 130 (100) 130 (100) 130 (100) 130 (100) Polyurethane component 9 22.8 9 20.6 concentration (wt %) Viscosity of composition (Pa .Math. s) 12 21 3 7 Cured product Rupture elongation (%) 2.4 4.3 1.1 4.6 characteristic Elastic modulus (GPa) 3.1 1.2 3.2 0.8 Rupture strength (MPa) 44.6 39.5 42.4 37.3 Tg ( C.) 129 111 125 106 Storage Measurement at 1.3 0.8 1.2 0.7 modulus 40 C. (GPa) E Measurement at 31.6 10.4 28.6 9.5 170 C. (MPa) Fracture toughness K.sub.1C 1.20 1.10 0.52 1.11 (MPa .Math. m.sup.0.5) (Remark) In the table, a numerical value in parentheses ( ) represents a wt %.

INDUSTRIAL APPLICABILITY

[0108] The resin composition and cured product of the polyurethane-modified epoxy resin of the present invention can be suitably utilized in various applications, such as matrices for composite materials, adhesives, coating materials, and electrical and electronic materials.