thermosetting resins

Abstract

This disclosure relates to a thermosetting resin obtainable by reacting 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with a mixture of divanillic alcohol ethers. This disclosure also relates to a thermosetting resin obtained from said thermosetting resin.

Description

Title of the invention: thermosetting resins Technical field of the invention

[0001] This disclosure relates to a thermosetting resin obtained by reacting 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide with a mixture of divanillic alcohol ethers. This disclosure also relates to a thermosetting resin obtained from said thermosetting resin. State of the art

[0002] Epoxy resins are often the matrix of choice for high-performance composites due to their exceptional mechanical properties, low density, and ease of handling and processing. However, epoxy resins have undeniable drawbacks in aerospace applications, as their flammability and poor compatibility with liquid oxygen can limit their applicability. Numerous studies have addressed this problem, and the proposed solutions consist of simply incorporating a flame retardant into the epoxy precursors to increase the resins' resistance to ignition and self-extinguishing properties. The most widely used epoxy precursor in many applications, including in the aerospace field, is DGEBA (bisphenol A diglycidyl ether).The flame retardant commonly used in conjunction with DGEBA (due to its moderate price and high effectiveness) is tetrabromobisphenol A (TBBPA). However, this compound contains bromine, which raises numerous concerns regarding its potential toxicity, persistence, and bioaccumulation. Consequently, the production and use of halogenated flame retardants have been regulated and restricted.

[0003] Organic phosphorus-based flame retardants have been considered as an alternative to halogenated flame retardants. Although the former are less harmful to the environment than the latter, they still have a potential negative impact on the environment, particularly due to the difficulty of processing the materials or substances that contain them.

[0004] Furthermore, the use of DGEBA in carbon fiber reinforced composites, in addition to the problems of high flammability and poor compatibility with liquid oxygen, can also pose environmental and health problems. As a derivative of bisphenol A, which is a reprotoxic fuel-based substance subject to strict regulations, this epoxy precursor now has an uncertain future, as an increasing amount of research is being devoted to finding healthier and more environmentally friendly alternatives. Among the sources Potential renewable resources for DGEBA substitutes include vegetable oils, which are notable for their abundant availability and relatively low price, but their derivatives can be disappointing in terms of performance due to their aliphatic structure. Epoxy thermosets with a more rigid backbone can be obtained from synthons, such as rosin, glucose derivatives, cardanol, and others, as recently reported, but they are generally not comparable to conventional DGEBA-based epoxy networks in terms of thermal and thermomechanical properties. Tannins and lignin could be promising sources of aromatic synthons, but their variable and complex structure, along with their low processability, limits their potential as bisphenol A substitutes.

[0005] Recently, pluriepoxide biphenyl compounds have been described as potential substitutes for DGEBA (see WO 2019 / 092359 and WO 2019 / 155169). Many of these compounds can be obtained from vanillin, a natural product. They are non-hazardous aromatic compounds derived from biomass and available on an industrial scale. Representative bio-based pluriepoxide compounds have demonstrated good thermomechanical properties, particularly in terms of glass transition temperature and coke content.

[0006] In this context, the inventors set themselves the specification of developing precursors of epoxy resins (thermo-cured) exhibiting thermomechanical properties compatible with, in particular, use in the aerospace field. Summary of the invention

[0007] This disclosure relates to a thermosetting resin that can be obtained by reaction between 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether.

[0008] In some embodiments, divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of about 10:90 to about 30:70.

[0009] In some embodiments, the mass ratio between the DOPO and said mixture is from about 1:1 to about 1:20.

[0010] This disclosure also relates to a thermosetting resin obtained by heat treatment, in the presence of a hardener, of a thermosetting resin as defined above.

[0011] This disclosure also relates to a composite material comprising such a thermosetting resin. Description of the figures

[0012] Figures 1, 3, 4 and 5 each represent an FTIR spectrum (acronym for "Fourier Transform Infrared spectroscopy") of a thermosetting resin according to the invention.

[0013] Figure [Fig. 2] represents the NMR spectrum of a thermosetting resin conforming to the invention.

[0014] Figure 6 represents the TGA curves (acronym for "ThermoGravimetric"). Analysis") of thermosetting resins according to the invention and outside the invention; from left to right, over the temperature range 600-800°C: DGEBA-DDS, GEDVA-DDS, P-GEDVA-DDS (5:1) and P-GEDVA-DDS (1:1) resins. Description of the invention

[0015] This disclosure relates to a thermosetting resin that can be obtained by reaction between 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether.

[0016] In the context of this disclosure, "GEDVA" means a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether, and "P-GEDVA" means the reaction product between GEDVA and DOPO.

[0017] DOPO (CAS: 35948-25-5), represented by the formula below, is commercially available:

[0018] Divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are respectively represented by the following formulas:

[0019] These compounds can be prepared for example as described in WO 2019 / 155169.

[0020] In some embodiments, divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of about 10:90 to about 30:70. In some embodiments, divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of about 15:85 to about 25:75.

[0021] In some embodiments, the mass ratio between the DOPO and said mixture is from about 1:1 to about 1:20. In some embodiments, the mass ratio between the DOPO and said mixture is from about 1:2 to about 1:10.

[0022] In some embodiments, the reaction between DOPO and the mixture of divanillic alcohol triglycidyl ethers is carried out at a temperature ranging from approximately 80°C to approximately 200°C, for example, at a temperature ranging from approximately 100°C to approximately 180°C. In some embodiments, said reaction is carried out for a duration ranging from approximately 30 min to approximately 100 min, for example, for a duration ranging from approximately 1 h to approximately 5 h. The reaction is carried out under inert conditions, typically under argon.

[0023] This disclosure also relates to a thermosetting resin obtained by heat treatment, in the presence of a hardener, of a thermosetting resin as defined above.

[0024] In some embodiments, the mass ratio between the thermosetting resin and the hardener is from about 2:1 to about 15:1. In some embodiments, the mass ratio between the thermosetting resin and the hardener is from about 3:1 to about 10:1.

[0025] In some embodiments, the hardener is selected from diaminodiphenyl sulfone, diaminodiphenylmethane (or methylene dianiline), isophorone diamine, dicyandiamide, 4,4-methylene-bis(2-isopropyl-6-methylaniline), and 4,4'-methylene-bis(2,6-diisopropylamineaniline). In some advantageous embodiments, the hardener is diaminodiphenyl sulfone.

[0026] This disclosure also relates to a thermosetting resin obtained by reaction between 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether, and a hardener.

[0027] In certain embodiments, the mass ratio between said mixture of divanillic alcohol ethers, DOPO and hardener is from about 3:1:1 to about 15:1:5.

[0028] In some embodiments, divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of about 10:90 to about 30:70. In some embodiments, divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of about 15:85 to about 25:75.

[0029] In some embodiments, the hardener is selected from diaminodiphenyl sulfone, diaminodiphenylmethane (or methylene dianiline), isophorone diamine, dicyandiamide, 4,4-methylene-bis(2-isopropyl-6-methylaniline), and 4,4'-methylene-bis(2,6-diisopropylamineaniline). In some advantageous embodiments, the hardener is diaminodiphenyl sulfone.

[0030] This disclosure is illustrated by the following examples. Example 1

[0031] 2.76 g of a mixture of triglycidyl divanillic alcohol ether and tetraglycidyl Divanillic alcohol ether, in a mass ratio of 20:80, was placed in a round-bottom flask equipped with an argon inlet and a vacuum system. The flask was then placed in an oil bath and heated to 80°C. The mixture was stirred and placed under vacuum for 15 minutes, after which argon was introduced into the flask until atmospheric pressure was reached. 0.29 g of DOPO was added, and the mixture was again stirred and placed under vacuum at 80°C to remove traces of water. Argon was introduced into the flask until atmospheric pressure was reached, and the reaction mixture was gradually heated to 100°C and maintained at this temperature for 5 hours.

[0032] The reaction product was analyzed by Fourier transform infrared spectroscopy ([Fig. 1]) and by NMR ([Fig. 2]). The epoxy equivalent weight (EEW) of the reaction product was 253. The value of EEW can be determined by methods well known to those skilled in the art, for example by chemical titration with HBr. Example 2

[0033] The protocol of Example 1 was repeated (mass ratio between the ether and DOPO mixture of approximately 10:1), but maintaining the reaction mixture at 100°C for 1h. The reaction product was analyzed by Fourier transform infrared spectroscopy ([Fig. 3]). The mass of the reaction product as epoxy equivalent was 233. Example 3

[0034] The protocol of Example 1 was repeated, but using 1.34 g of a mixture of divanillic alcohol ethers and 0.69 g of DOPO (mass ratio of approximately 2:1) and maintaining the reaction mixture at 100°C for 5 h. The reaction product was analyzed by Fourier transform infrared spectroscopy ([Fig. 4]). The epoxy equivalent mass of the reaction product was 272. Example 4

[0035] The protocol of Example 3 was repeated (mass ratio between the ether and DOPO mixture of approximately 2:1), but the reaction mixture was maintained at 160°C for 5 h. The reaction product was analyzed by Fourier transform infrared spectroscopy ([Fig. 5]). The mass of the reaction product as epoxy equivalent was 430. Example 5

[0036] 2.37 g of the resin obtained in Example 2 was placed in a flask which was heated to 80°C, then 0.65 g of diaminodiphenyl sulfone (DDS) was added, and the mixture was heated under vacuum to 140°C for complete dissolution of the DDS. The mixture was cooled as soon as it became clear.

[0037] The mixture was then transferred into 5 cm diameter aluminum molds to produce resin plates 1 to 2 mm thick, or into larger aluminum molds to produce resin plates 175 x 150 x 5 mm. The plates were then cured in an air-circulating oven at 130°C for 1 hour, followed by post-curing at 170°C for 2 hours. A sample of the resin plate was analyzed by thermogravimetry under an air atmosphere ([Fig. 6]), and the residual coke content of the resin after degradation at 800°C was determined. The result is presented in Table 1 below. Example 6

[0038] 5.04 g of a mixture of triglycidyl divanillic alcohol ether and tetraglycidyl Divanillic alcohol ether, in a mass ratio of 20:80, was placed in a round-bottom flask equipped with an argon inlet and a vacuum system. The flask was then placed in an oil bath and heated to 80°C. The mixture was stirred and evacuated for 15 minutes, after which argon was introduced into the flask until atmospheric pressure was reached. 1.01 g of DOPO and then 1.1 g of DSS were added, and the mixture was again stirred and evacuated to 80°C to remove traces of water. Argon was introduced into the flask until atmospheric pressure was reached. The mixture was heated under vacuum to 140°C to obtain a clear mixture, which was then cooled.

[0039] The mixture was then transferred into 5 cm diameter aluminum molds to produce resin plates 1 to 2 mm thick, or into Larger aluminum molds were used to produce resin plates measuring 175 x 150 x 5 mm. The plates were then cured in an air-circulating oven at 130°C for 1 hour, followed by post-curing at 170°C for 2 hours. A resin plate sample was analyzed by thermogravimetry under an air atmosphere ([Fig. 6]), and the residual coke content of the resin after degradation at 800°C (R800) was determined. The results are presented in Table 1 below. Example 7

[0040] 1.34 g of a mixture of triglycidyl divanillic alcohol ether and tetraglycidyl Divanillic alcohol ether, in a mass ratio of 20:80, was placed in a round-bottom flask equipped with an argon inlet and a vacuum system. The flask was then placed in an oil bath and heated to 80°C. The mixture was stirred and placed under vacuum for 15 minutes, after which argon was introduced into the flask until atmospheric pressure was reached. 0.69 g of DOPO was added, and the mixture was again stirred and placed under vacuum at 80°C to remove traces of water. Argon was introduced into the flask until atmospheric pressure was reached, and the reaction mixture was gradually heated to 100°C and maintained at this temperature for 5 hours.

[0041] 0.50 g of this resin was placed in a flask which was heated to 80°C, then 0.05 g of diaminodiphenyl sulfone (DDS) was added, and the mixture was heated under vacuum to 140°C for complete dissolution of the DDS. The mixture was cooled as soon as it became clear.

[0042] The mixture was then transferred into 5 cm diameter aluminum molds to produce resin plates 1 to 2 mm thick, or into larger aluminum molds to produce resin plates 175 x 150 x 5 mm. The plates were then cured in an air-circulating oven at 130°C for 1 hour, followed by post-curing at 170°C for 2 hours. A sample of the resin plate was analyzed by thermogravimetry under an air atmosphere ([Fig. 6]), and the residual coke content of the resin after degradation at 800°C was determined. The result is presented in Table 1 below. Comparative example

[0043] 1.64 g of a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether, in a mass ratio of 20:80, was placed in a flask which was heated to 80°C, then 0.66 g of diaminodiphenyl sulfone (DDS) was added, and the mixture was heated under vacuum to 140°C for complete dissolution of the DDS. The mixture was cooled as soon as it became clear.

[0044] The mixture was then transferred into 5 cm diameter aluminum molds to produce resin plates 1 to 2 mm thick, or into Larger aluminum molds were used to produce resin plates measuring 175 x 150 x 5 mm. The plates were then cured in an air-circulating oven at 130°C for 1 hour, followed by post-curing at 170°C for 2 hours. A resin plate sample was analyzed by thermogravimetry under nitrogen and air atmospheres ([Fig. 6]), and the residual coke content of the resin after degradation at 800°C (R800) was determined. The results are presented in Table 1 below.

[0045] [Tables 1] Example R800 Comparative example 1.7 Example 6 2.4 Example 7 24.4

[0046] As can be seen from Table 1, the residual mass at 800°C of the thermosetting resins according to the invention is at least 40% greater than that obtained without the use of DOPO. This is very advantageous since the higher the residual coke content, the better the flame-retardant properties of the materials in question.

[0047] The thermosetting resins described in this disclosure, in addition to the advantage of being bio-based, exhibit, once hardened, increased thermal resistance.

Claims

Demands

1. Thermosetting resin obtainable by reaction between 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether.

2. Thermosetting resin according to claim 1, wherein divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of 10:90 to 30:

70.

3. Thermosetting resin according to claim 2, wherein divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of 15:85 to 25:

75.

4. Thermosetting resin according to any one of the preceding claims, wherein the mass ratio between DOPO and said mixture is from 1:1 to 1:

20.

5. Thermosetting resin according to claim 2, wherein the mass ratio between DOPO and said mixture is 1:2 to 1:

10.

6. Thermosetting resin obtained by heat treatment, in the presence of a hardener, of a thermosetting resin according to any one of claims 1 to 5.

7. Thermosetting resin according to claim 6, wherein the hardener is selected from diaminodiphenyl sulfone, diaminodiphenylmethane, isophorone diamine, dicyandiamide, 4,4-methylene-bis(2-isopropyl-6-methylaniline) and 4,4'-methylene-bis(2,6-diisopropylamineaniline).

8. Thermosetting resin capable of being obtained by reaction between 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, a mixture of divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether, and a hardener.

9. Thermosetting resin according to claim 8, wherein divanillic alcohol triglycidyl ether and divanillic alcohol tetraglycidyl ether are present in said mixture in a mass ratio of 10:90 to 30:

70.

10. Thermosetting resin according to claim 8 or claim 9, wherein the hardener is selected from diaminodiphenyl sulfone, diaminodiphenylmethane, isophorone diamine, dicyandiamide, the 4,4-methylene-bis(2-isopropyl-6-methylaniline) and the 4,4'-methylene-bis(2,6-diisopropylamineaniline).

11. Composite material comprising a thermosetting resin according to any one of claims 6 to 10.

Images