A transparent environment-friendly intrinsic flame-retardant epoxy resin material and a preparation method and application thereof

Abstract

The application discloses a kind of transparent environmental protection intrinsic flame-retardant epoxy resin material and preparation method and application thereof.The intrinsic flame-retardant epoxy resin material is prepared by high-temperature melting method according to certain proportion by isocyanuric acid triglycidyl ester and dicarboxylic acid, acid anhydride or diacid ester reaction.The obtained intrinsic flame-retardant epoxy resin material flame-retardant function is mainly given by isocyanurate ring, with it as the main structure of material, can make material have excellent thermal stability, mechanical property and halogen-free flame-retardant performance;Flexible fatty chain introduced by curing agent and ester group produced by reaction, so that the material has excellent toughness and environmental protection degradable performance;The application combines bulk melting reaction and casting forming process, and can prepare highly transparent and arbitrary shape, with intrinsic halogen-free flame-retardant function, environmental protection degradable high-performance thermosetting resin, which can be used as environmental protection flame-retardant organic glass in building, transportation, aviation, home, electronic and other industries, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material, its preparation method, and its application. Background Technology

[0002] Epoxy resin materials have excellent mechanical properties, bonding properties, chemical stability and dimensional stability, and are therefore widely used in transportation, construction, electronics, machinery and other fields. However, as an organic resin material, epoxy resin has the disadvantages of being flammable and not flame retardant, which seriously restricts its application and development.

[0003] Over the past few decades, numerous approaches and methods have been employed to improve the flame retardant properties of epoxy resins. Currently, there are two main types of flame-retardant modified epoxy resins: additive flame-retardant epoxy resins and reactive flame-retardant epoxy resins. Additive flame-retardant epoxy resins involve adding flame retardants to the material through physical blending, which can easily lead to uneven dispersion and exudation, resulting in reduced physicochemical properties and stability of the material. In contrast, reactive flame-retardant epoxy resins, also known as intrinsically flame-retardant epoxy resins, possess both excellent flame-retardant properties and maintain the material's other inherent performance advantages.

[0004] Currently, most intrinsically flame-retardant epoxy resins are prepared by epoxidation of small molecules containing flame-retardant elements. However, this method is not only complex in its preparation process, but also results in epoxy resin materials that lack transparency after curing. Previous studies have introduced isocyanurate rings into the polymer structure to modify materials for flame retardancy. These studies have demonstrated that isocyanurate rings can absorb a large amount of heat during high-temperature pyrolysis, and that the isocyanurate ring molecular structure contains a high content of nitrogen elements with flame-retardant properties, exhibiting halogen-free flame-retardant performance. However, traditional flame-retardant materials containing isocyanurate rings typically use compounds with this structure as flame-retardant additives in epoxy resins, resulting in less than ideal flame-retardant and other properties. Therefore, how to prepare an intrinsically flame-retardant epoxy resin that improves its flame-retardant properties while maintaining its transparency and other superior properties is a pressing technical problem that needs to be solved. Summary of the Invention

[0005] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material.

[0006] The epoxy resin material of this invention is prepared by reacting triglycidyl isocyanurate with a specific curing agent (dicarboxylic acid, acid anhydride, or diester acid ester) in a specific ratio. The reaction produces hydroxyl groups, which further react with unreacted raw materials, particularly epoxy groups, to obtain an epoxy resin material with flame-retardant properties. The molecular structure of the prepared material mainly consists of isocyanurate rings, aliphatic carbon chains, and ester bonds. The high density of isocyanurate rings in the cross-linked structure endows the material with rigidity, heat resistance, weather resistance, and flame-retardant properties, while the aliphatic carbon chains impart toughness. Simultaneously, the presence of ester bonds gives the material environmentally friendly and biodegradable (hydrolytic) properties. This invention can process and prepare a highly transparent, halogen-free, flame-retardant, environmentally friendly, biodegradable (hydrolytic) thermosetting resin, which has broad application prospects as a flame-retardant acrylic glass in industries such as construction, transportation, aviation, home furnishings, and electronics.

[0007] Another object of the present invention is to provide a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material prepared by the above preparation method.

[0008] Another object of the present invention is to provide the application of the above-mentioned transparent and environmentally friendly intrinsically flame-retardant epoxy resin material.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] A method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material includes the following steps:

[0011] Triglycidyl isocyanurate and a curing agent are polymerized at a molar ratio of 1:(0.75-1.5) under catalysis and heating conditions to obtain an intrinsically flame-retardant epoxy resin; the curing agent includes at least one of dicarboxylic acids and acid anhydrides.

[0012] Preferably, the structural formula of the triglycidyl isocyanurate is:

[0013]

[0014] Preferably, the general structural formulas of the dicarboxylic acid and the acid anhydride are as follows:

[0015]

[0016] In the formula, R is C2-C 20 Alkylene, C0-C with aromatic substituents 20 alkylene or A1 and A2 are independently C1-C3 alkylene groups and are connected in the general structural formula as linking points; A3 is hydrogen, methyl, or a benzene ring.

[0017] More preferably, the curing agent is at least one selected from adipic acid, octanoic acid, dodecanoic acid, sebacic anhydride, phthalic anhydride, terephthalic acid, 1,3-dicarboxypropyl-5-phenyl isocyanurate, and 1,3-dicarboxypropyl-5-methyl isocyanurate.

[0018] Preferably, the curing agent further includes a diester acid ester with the general structural formula: In the formula, R is C2-C 20 Alkylene, C0-C with aromatic substituents 20 alkylene or A1 and A2 are independently C1-C3 alkylene groups and are connected in the general structural formula as linking points; A3 is hydrogen, methyl, or a benzene ring; R1 is methyl, ethyl, isopropyl, or tert-butyl; the diester accounts for 0-50% of the total molar amount of the curing agent; more preferably 0-38.5%; and most preferably 25-38.5%.

[0019] More preferably, the diester is 1,3-dimethyl ethyl isocyanurate.

[0020] Preferably, the catalyst is at least one selected from zinc chloride, zinc acetate, stannous chloride, ferric chloride, boron trifluoride, sodium methoxide, stannous isooctanoate, dibutyltin dilaurate, zinc acetylacetone, tetrabutyl titanate, 1,8-diazabicycloundec-7-ene, 1,5,7-triazidobicyclodec-5-ene, 7-methyl-1,5,7-triazidobicyclodec-5-ene, 2,4,6-tris(dimethylaminomethyl)phenol, dimethylcyclohexylamine, 4-dimethylaminopyridine, and methanesulfonic acid.

[0021] Preferably, the amount of catalyst used is 1 to 50‰ of the total mass of the reactants; more preferably, it is 6 to 50‰.

[0022] Preferably, the heating temperature is 100-150°C and the polymerization reaction time is 3-25 hours; more preferably, the polymerization reaction is carried out at 100-130°C for 4-25 hours.

[0023] Preferably, the polymerization reaction is carried out in an inert gas atmosphere, wherein the inert gas is at least one of nitrogen and rare gases.

[0024] Preferably, the polymerization reaction includes a bulk melt pre-reaction and a casting molding reaction (post-curing); the bulk melt pre-reaction is carried out under normal pressure and an inert gas atmosphere for 10 to 60 minutes; the casting molding reaction (post-curing) is carried out under a pressure of 0 to 101 kPa for 4 to 24 hours.

[0025] Preferably, the preparation method of the transparent and environmentally friendly intrinsically flame-retardant epoxy resin material includes the following steps:

[0026] (1) Under normal pressure and inert gas atmosphere, triglycidyl isocyanurate and curing agent are heated to 100-150℃ and melted under the action of catalyst, and then pre-reacted for 10-60 min;

[0027] (2) Pour the pre-reaction mixture from step (1) into a mold and cure it at 100-150°C under a pressure of 0-101 kPa for 4-24 hours to obtain an intrinsic flame-retardant epoxy resin.

[0028] The intrinsically flame-retardant epoxy resin reaction process described in this invention:

[0029]

[0030] The above preparation method yields a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material.

[0031] Preferably, the transparent and environmentally friendly intrinsically flame-retardant epoxy resin material has the following general structural formula:

[0032]

[0033] In the formula, R is C2-C 20 Alkylene, C0-C with aromatic substituents 20 alkylene or A1 and A2 are independently C1-C3 alkylene groups and are connected in the general structural formula as linking points; A3 is hydrogen, methyl, or a benzene ring; R1 is methyl, ethyl, isopropyl, or tert-butyl.

[0034] The above-mentioned transparent and environmentally friendly intrinsically flame-retardant epoxy resin materials are used in construction, transportation, aviation, home furnishing, and electronic materials.

[0035] The transparent and environmentally friendly intrinsically flame-retardant epoxy resin material of this invention is prepared through bulk melt reaction and casting molding processes. This method can produce highly transparent epoxy resin materials of arbitrary shapes, which can be used as flame-retardant acrylic glass. However, triglycidyl isocyanurate requires a high temperature of over 100°C to melt before it can react. Under these conditions, conventional amine curing agents are too reactive and react immediately upon mixing with triglycidyl isocyanurate, even causing explosive polymerization, making it impossible to process and mold. Therefore, this invention uses dicarboxylic acids, anhydrides, or diesters with low reactivity as curing agents for this system.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] (1) The flame retardant properties of the transparent and environmentally friendly intrinsically flame-retardant epoxy resin material of the present invention are mainly provided by triglycidyl isocyanurate. Using it as the main resin of the material system can make the material have excellent rigidity, thermal stability and intrinsic flame retardant properties, so there is no need to add other flame retardants. While the high density of isocyanurate rings brings high rigidity and high strength, it also makes the material more brittle. However, using dicarboxylic acids, anhydrides or diesters as curing agents can introduce aliphatic segments, which can improve the toughness of the material without sacrificing the mechanical strength of the material. At the same time, the introduced aliphatic segments do not cause the flame retardant properties of the material to decrease, thus overcoming the technical defect in the prior art that the introduction of aliphatic segments will significantly reduce the flame retardancy of the material.

[0038] (2) The triglycidyl isocyanurate in this invention reacts with carboxylic acids, anhydrides or organic acid esters to form ester bonds, giving the material degradable (hydrolyzable) properties and environmentally friendly characteristics; the resulting intrinsically flame-retardant epoxy resin material can be hydrolyzed in both acidic and alkaline solutions, especially in alkaline solutions with low concentrations where it can be completely hydrolyzed and dissolved in the solution, while it will not be hydrolyzed after long-term immersion in neutral water, which ensures the durability of the material during use.

[0039] (3) This invention combines bulk melting reaction and casting molding process to prepare highly transparent and arbitrary-shaped, environmentally friendly, degradable (hydrolytic) high-performance thermosetting resin with intrinsic halogen-free flame retardant function. It can be used as an environmentally friendly flame-retardant plexiglass in the construction, transportation, aviation, home furnishing, and electronics industries with broad application prospects. Attached Figure Description

[0040] Figure 1 This is a digital photograph of the sample obtained in Example 1.

[0041] Figure 2 Tensile tests were performed on the samples obtained in Examples 1-7.

[0042] Figure 3 This is a digital photograph of the combustion test process of the sample obtained in Example 1.

[0043] Figure 4 This is a digital photograph of the degradation (hydrolysis) process of the sample obtained in Example 1. Detailed Implementation

[0044] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0045] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0046] Comparative Example 1

[0047] Under a nitrogen atmosphere, 297.2 g (1.0 mol) of triglycidyl isocyanurate, 233.8 g (1.6 mol) of adipic acid, and 3.0 g of 1,5,7-triazidobiscyclodec-5-ene were added to a three-necked flask. The mixture was heated and stirred at 130 °C for 20 min. The mixture was then poured into a mold and reacted at 101 kPa and 130 °C for 12 h to obtain an epoxy resin material. Vertical burning tests showed that it did not meet any UL-94 rating and therefore lacked flame retardant properties.

[0048] Comparative Example 2

[0049] 297.2 g (1.0 mol) of triglycidyl isocyanurate, 87.7 g (0.6 mol) of adipic acid, and 3.0 g of 1,5,7-triazidobiscyclodec-5-ene were added to a three-necked flask under a nitrogen atmosphere. The mixture was heated and stirred at 130 °C for 20 min. The mixture was then poured into a mold and reacted at 101 kPa and 130 °C for 12 h to obtain an epoxy resin material. Vertical burning tests showed that it did not meet any UL-94 rating and did not possess flame-retardant properties.

[0050] Comparative Example 3

[0051] Under a nitrogen atmosphere, 297.2 g (1.0 mol) of triglycidyl isocyanurate, 233.8 g (1.6 mol) of adipic acid, 56.5 g (0.25 mol) of 1,3-dimethyl ethyl isocyanurate, and 3.0 g of 1,5,7-triazidobiscyclodec-5-ene were added to a three-necked flask. The mixture was heated and stirred at 130 °C for 20 min. The mixture was then poured into a mold, and the pressure was reduced to 0.01 kPa and reacted at 130 °C for 12 h to obtain an epoxy resin material. A vertical burning test showed that it did not meet any UL-94 rating and did not exhibit flame retardant properties. This indicates that even with the addition of a flame-retardant curing agent (1,3-dimethyl ethyl isocyanurate) to the mixture in Comparison 1, a epoxy resin material with good flame retardant properties cannot be obtained.

[0052] Example 1

[0053] 297.2 g (1.0 mol) of triglycidyl isocyanurate, 146.1 g (1.0 mol) of adipic acid, and 3.0 g of 1,5,7-triazidobiscyclodec-5-ene were added to a three-necked flask under a nitrogen atmosphere. The mixture was heated and stirred at 130 °C for 20 min. The mixture was then poured into a mold and reacted at 101 kPa and 130 °C for 12 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 332.4 °C. Tensile testing revealed a tensile strength of 53.4 MPa and an elongation at break of 60%. Vertical burning testing showed a flame retardancy rating of V-0 (UL-94). The limiting oxygen index (LOI) was 28.0%.

[0054] Example 2

[0055] 297.2 g (1.0 mol) of triglycidyl isocyanurate, 103.3 g (0.6 mol) of octanoic acid, 43.8 g (0.3 mol) of adipic acid, and 6.6 g of sodium methoxide were added to a three-necked flask under nitrogen atmosphere and heated and stirred at 100 °C for 60 min. The mixture was then poured into a mold and reacted at 101 kPa and 100 °C for 24 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 331.5 °C. Tensile testing and vertical burning tests showed a tensile strength of 41.9 MPa and an elongation at break of 80%. The flame retardant performance reached V-0 (UL-94) rating. The limiting oxygen index (LOI) was 26.5%.

[0056] Example 3

[0057] 297.2 g (1.0 mol) of triglycidyl isocyanurate, 172.6 g (0.75 mol) of dodecanoic acid, and 23.5 g of zinc chloride were added to a three-necked flask under nitrogen atmosphere and heated and stirred at 110 °C for 40 min. The mixture was then poured into a mold and reacted at 101 kPa and 110 °C for 24 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 320.4 °C. Tensile testing revealed a tensile strength of 37.4 MPa and an elongation at break of 120%. Vertical burning testing showed its flame retardancy reached V-1 level (UL-94). The limiting oxygen index (LOI) was 25.7%.

[0058] Example 4

[0059] Under nitrogen atmosphere, 297.2 g (1.0 mol) of triglycidyl isocyanurate, 172.6 g (0.75 mol) of dodecanoic acid, 56.5 g (0.25 mol) of 1,3-dimethyl ethyl isocyanurate, and 5.7 g of boron trifluoride were added to a three-necked flask. The mixture was heated and stirred at 100 °C for 60 min. The mixture was poured into a mold, and the pressure was reduced to 0.05 kPa and reacted at 100 °C for 24 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 335.2 °C. Tensile testing showed a tensile strength of 57.4 MPa and an elongation at break of 30%. Vertical burning testing showed its flame retardancy reached V-0 (UL-94) rating. The limiting oxygen index (LOI) was 30.3%.

[0060] Example 5

[0061] Under nitrogen atmosphere, 297.2 g (1.0 mol) of triglycidyl isocyanurate, 86.1 g (0.5 mol) of octanoic acid, 92.1 g (0.5 mol) of sebacic anhydride, 90.7 g (0.35 mol) of 1,3-dicarboxypropyl-5-methylisocyanurate, and 5.7 g of tetrabutyl titanate were added to a three-necked flask. The mixture was heated and stirred at 100 °C for 50 min. The mixture was then poured into a mold and reacted at 101 kPa and 100 °C for 24 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 329.4 °C. Tensile testing revealed a tensile strength of 62.0 MPa and an elongation at break of 30%. Vertical burning testing showed its flame retardancy reached V-0 (UL-94) rating. The limiting oxygen index (LOI) was 33.0%.

[0062] Example 6

[0063] Under nitrogen atmosphere, 297.2 g (1.0 mol) of triglycidyl isocyanurate, 111.1 g (0.75 mol) of phthalic anhydride, 57.5 g (0.25 mol) of dodecanoic acid, 188.5 g (0.5 mol) of 1,3-biscarboxypropyl-5-phenylisocyanurate, and 5.6 g of 4-dimethylaminopyridine were added to a three-necked flask. The mixture was heated and stirred at 130 °C for 30 min. The mixture was then poured into a mold and reacted at 101 kPa and 130 °C for 4 h to obtain an environmentally friendly intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 338.2 °C. Tensile testing revealed a tensile strength of 88.7 MPa and an elongation at break of 25%. Vertical burning tests showed its flame retardancy reached UL-94V-0 rating. The limiting oxygen index (LOI) was 35.5%.

[0064] Example 7

[0065] 297.2 g (1.0 mol) of triglycidyl isocyanurate, 132.9 g (0.8 mol) of terephthalic acid, 112.9 g (0.5 mol) of 1,3-dimethyl ethyl isocyanurate, and 8.3 g of zinc acetylacetonate were added to a three-necked flask under nitrogen atmosphere and heated and stirred at 120 °C for 50 min. The mixture was then poured into a mold, and the pressure was reduced to 0.1 kPa and reacted at 120 °C for 24 h to obtain a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material. TGA analysis showed its 5% thermal decomposition temperature to be 333.5 °C. Tensile testing showed a tensile strength of 69.1 MPa and an elongation at break of 40%. Vertical burning testing showed its flame retardancy reached UL-94V-0 rating. The limiting oxygen index (LOI) was 37.2%.

[0066] Performance testing

[0067] The intrinsic flame-retardant epoxy resin materials obtained in Examples 1-7 were subjected to performance tests, wherein:

[0068] Tensile testing: The tensile properties of the material were determined according to the national standard GB / T 1040.3-2006;

[0069] TGA: TGA analysis was performed using a NETZSCH TG 209F3 thermogravimetric analyzer with a heating rate set at 20℃ / min and an N2 atmosphere.

[0070] Vertical burning test: The vertical burning test was conducted in accordance with the national standard GB / T 2408-2008;

[0071] Limiting oxygen index: The limiting oxygen index is tested according to the national standard GB / T 2406-1993.

[0072] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a transparent, environmentally friendly, intrinsically flame-retardant epoxy resin material, characterized in that, Includes the following steps: Triglycidyl isocyanurate and a curing agent are polymerized at a molar ratio of 1:(0.75-1.5) under catalysis and heating conditions to obtain an intrinsically flame-retardant epoxy resin; the curing agent includes at least one of dicarboxylic acids and acid anhydrides; The structural formula of the triglycidyl isocyanurate is: ； The general structural formulas of the dicarboxylic acid and acid anhydride are as follows: ； In the formula, R is C2-C 20 Alkylene, C0-C with aromatic substituents 20 alkylene or A1 and A2 are independently C1-C3 alkylene groups and are connected in the general structural formula as linking points; A3 is hydrogen, methyl, or a benzene ring. The curing agent also includes a diester, with the general structural formula as follows: In the formula, R is C2-C 20 Alkylene, C0-C with aromatic substituents 20 alkylene or A1 and A2 are independently C1-C3 alkylene groups and are connected in the general structural formula as linking points; A3 is hydrogen, methyl, or a benzene ring; R1 is methyl, ethyl, isopropyl, or tert-butyl; the diester accounts for 0-50% of the total molar amount of the curing agent; The heating temperature is 100–150°C, and the polymerization reaction time is 3–25 h.

2. The method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material according to claim 1, characterized in that, The curing agent is at least one selected from adipic acid, octanoic acid, dodecanoic acid, sebacic anhydride, phthalic anhydride, terephthalic acid, 1,3-dicarboxypropyl-5-phenyl isocyanurate, and 1,3-dicarboxypropyl-5-methyl isocyanurate.

3. The method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material according to claim 1, characterized in that, The diester is 1,3-dimethyl ethyl isocyanurate; the diester accounts for 0 to 38.5% of the total molar amount of the curing agent.

4. The method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material according to claim 1, characterized in that, The catalyst is at least one selected from zinc chloride, zinc acetate, stannous chloride, ferric chloride, boron trifluoride, sodium methoxide, stannous isooctanoate, dibutyltin dilaurate, zinc acetylacetone, tetrabutyl titanate, 1,8-diazabicycloundec-7-ene, 1,5,7-triazidobicyclodec-5-ene, 7-methyl-1,5,7-triazidobicyclodec-5-ene, 2,4,6-tris(dimethylaminomethyl)phenol, dimethylcyclohexylamine, 4-dimethylaminopyridine, and methanesulfonic acid. The amount of catalyst used is 1 to 50‰ of the total mass of the reactants.

5. The method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material according to claim 1, characterized in that, The polymerization reaction is carried out in an inert gas atmosphere, wherein the inert gas is at least one of nitrogen and rare gases; The polymerization reaction includes a bulk melt pre-reaction and a casting reaction, with a temperature of 100–150°C; the bulk melt pre-reaction is carried out under normal pressure and an inert gas atmosphere for 10–60 min; the casting reaction is carried out under a pressure of 0–101 kPa for 4–24 h.

6. The method for preparing a transparent and environmentally friendly intrinsically flame-retardant epoxy resin material according to claim 1, characterized in that, Includes the following steps: (1) Under normal pressure and inert gas atmosphere, triglycidyl isocyanurate and curing agent are heated to 100-150 °C and melted under the action of catalyst, and then pre-reacted for 10-60 min; (2) Pour the pre-reaction mixture from step (1) into a mold and cure it at 100-150 °C under a pressure of 0-101 kPa for 4-24 hours to obtain an intrinsic flame-retardant epoxy resin.

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