Epoxy resin composition, prepreg, and fiber-reinforced composite material

Patent metadata

Field	Value
Publication number	US-11345808-B2
Application number	US-201816628157-A
Country	US
Kind code	B2
Filing date	Jul 18, 2018
Priority date	Jul 21, 2017
Publication date	May 31, 2022
Grant date	May 31, 2022

Abstract

The present invention aims to provide an epoxy resin composition that is high in both fast curability and storage stability, a prepreg prepared by using the epoxy resin composition, and a fiber reinforced composite material prepared by curing the prepreg.The epoxy resin composition contains the following components [A], [B], [C], and [D] and meets the following requirements [a], [b], and [c]:[A]: epoxy resin,[B]: dicyandiamide,[C]: aromatic urea,[D]: borate ester,[a]: 0.014≤(content of component [D]/content of component [C])≤0.045,[b]: 0.9≤(number of moles of active groups in component [A]/number of moles of active hydrogen in component [B])≤1.2, and[c]: 14≤(content of component [A]/content of component [C])≤25.

First claim

The invention claimed is:

1. An epoxy resin composition comprising the following components [A], [B], [C], and [D] and meeting the following requirements [a], [b], and [c]:
[A]: epoxy resin,
[B]: dicyandiamide,
[C]: aromatic urea,
[D]: borate ester,
[a]: 0.014≤(content of component [D]/content of component [C])≤0.045,
[b]: 0.9≤(number of moles of active groups in component [A]/number of moles of active hydrogen in component [B])≤1.2, and
[c] 14≤(content of component [A]/content of component [C])≤25.

2. The epoxy resin composition as set forth in claim 1 that meets the following requirement 1 and requirement 2:
requirement 1: in dielectric measurement at 80° C., the time period from the start of the measurement until the cure index reaches 10% is 120 minutes or more, and
requirement 2: in dielectric measurement at 150° C., the time period from the start of the measurement until the cure index reaches 70% is 120 seconds or less.

3. The epoxy resin composition as set forth in claim 1 that meets the following requirement 3 and requirement 4:
requirement 3: the temperature at which the epoxy resin composition exhibits the lowest viscosity when the temperature is raised from 40° C. to 250° C. at a rate of 5° C./minute in dynamic viscoelasticity measurement is 110° C. or more and 140° C. or less, and
requirement 4: the difference between the heat generation onset temperature (T0) and the heat generation offset temperature (T1) during the period in which the epoxy resin composition is heated from 30° C. to 300° C. in a differential scanning calorimeter at a constant rate of 5° C./min is 25° C. or less.

4. The epoxy resin composition as set forth in claim 1 that meets the following requirement 5 and requirement 6:
requirement 5: in Curelastometer measurement at 150° C., the demolding index calculated by dividing the maximum torque (TH) by the volume of the sample is 0.40 N·m/cm 3 or more and 1.50 N·m/cm 3 or less, and
requirement 6: in Curelastometer measurement at 150° C., the time tm(70) from the start of the measurement until torque reaches 70% of the maximum torque is 150 seconds or less.

5. The epoxy resin composition as set forth in claim 1 , wherein the change in glass transition temperature that occurs during storage at 40° C. and 75% RH for 14 days is 20° C. or less.

6. The epoxy resin composition as set forth in claim 1 , wherein component [A] contains a tri- or higher functional epoxy resin.

7. The epoxy resin composition as set forth in claim 6 , wherein the following component [A1], used as the tri- or higher functional epoxy resin, accounts for 55 to 100 parts by mass in 100 parts by mass of component [A]:
[A1]: an epoxy resin as represented by formula (I) or an epoxy resin as represented by formula (II):

wherein in formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a methyl group, and n is an integer of 1 or more, and

wherein in formula (II), n is an integer of 1 or more.

8. A prepreg comprising the epoxy resin composition as set forth in claim 1 and reinforcing fiber.

9. A fiber reinforced composite material produced by curing the prepreg as set forth in claim 8 .

10. An epoxy resin composition comprising components [A], [B], [C], and [D], meeting the following requirements [d], [e], and [f], and also meeting the following requirement 1 and requirement 2:
[A]: epoxy resin, wherein component [A] contains a tri- or higher functional epoxy resin,
[B]: dicyandiamide,
[C]: aromatic urea,
[D]: borate ester,
[d]: 0.005≤(content of component [D]/content of component [C])≤0.045,
[e]: 0.9≤(number of moles of active groups in component [A]/number of moles of active hydrogen in component [B])≤1.3,
[f] 12≤(content of component [A]/content of component [C])≤26,
requirement 1: in dielectric measurement at 80° C., the time period from the start of the measurement until the cure index reaches 10% is 120 minutes or more, and
requirement 2: in dielectric measurement at 150° C., the time period from the start of the measurement until the cure index reaches 70% is 120 seconds or less,
wherein the following component [A1], used as the tri- or higher functional epoxy resin, accounts for 55 to 100 parts by mass in 100 parts by mass of component [A]:
[A1]: an epoxy resin as represented by formula (I) or an epoxy resin as represented by formula (II):

wherein in formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a methyl group, and n is an integer of 1 or more, and

wherein in formula (II), n is an integer of 1 or more.

11. The epoxy resin composition as set forth in claim 10 , wherein the change in glass transition temperature that occurs during storage at 40° C. and 75% RH for 14 days is 20° C. or less.

12. A prepreg comprising the epoxy resin composition as set forth in claim 10 and reinforcing fiber.

13. A fiber reinforced composite material produced by curing the prepreg as set forth in claim 12 .

14. An epoxy resin composition comprising components [A], [B], [C], and [D], meeting the requirements [d], [e], and [f], and also meeting the following requirement 3 and requirement 4:
[A]: epoxy resin, wherein component [A] contains a tri- or higher functional epoxy resin,
[B]: dicyandiamide,
[C]: aromatic urea,
[D]: borate ester,
[d]: 0.005≤(content of component [D]/content of component [C])≤0.045,
[e]: 0.9≤(number of moles of active groups in component [A]/number of moles of active hydrogen in component [B])≤1.3,
[f] 12≤(content of component [A]/content of component [C])≤26,
requirement 3: The temperature at which the epoxy resin composition exhibits the lowest viscosity when the temperature is raised from 40° C. to 250° C. at a rate of 5° C./minute in dynamic viscoelasticity measurement is 110° C. or more and 140° C. or less, and
requirement 4: the difference between the heat generation onset temperature (T0) and the heat generation offset temperature (T1) during the period in which the epoxy resin composition is heated from 30° C. to 300° C. in a differential scanning calorimeter at a constant rate of 5° C./min is 25° C. or less,
wherein the following component [A1], used as the tri- or higher functional epoxy resin, accounts for 55 to 100 parts by mass in 100 parts by mass of component [A]:
[A1]: an epoxy resin as represented by formula (I) or an epoxy resin as represented by formula (II):

wherein in formula (I), R 1 , R 2 , and R 3 are each independently a hydrogen atom or a methyl group, and n is an integer of 1 or more, and

wherein in formula (II), n is an integer of 1 or more.

15. The epoxy resin composition as set forth in claim 14 , wherein the change in glass transition temperature that occurs during storage at 40° C. and 75% RH for 14 days is 20° C. or less.

16. A prepreg comprising the epoxy resin composition as set forth in claim 14 and reinforcing fiber.

17. A fiber reinforced composite material produced by

Assignees

• Toray Industries

Inventors

• Takahashi Eiki
• Konishi Daisuke
• Miyoshi Masayuki
• Hirano Noriyuki

Classifications

• C08J5/249

  characterised by the additives used in the prepolymer mixture · CPC title

• C08J5/243

  using carbon fibres · CPC title

• C08J2363/00

  Characterised by the use of epoxy resins; Derivatives of epoxy resins · CPC title

• C08L63/00 Primary

  Compositions of epoxy resins; Compositions of derivatives of epoxy resins · CPC title

• C08K5/55

  Boron-containing compounds {(C08K5/0091 takes precedence)} · CPC title