Phosphorus-silicon modified anhydride curing agent and cured resin composition

Abstract

The invention discloses a phosphorus-silicon modified anhydride curing agent and a cured resin composition, and the phosphorus-silicon modified anhydride curing agent comprises the following raw materials in parts by mass: 80-90 parts of anhydride, 5-20 parts of hydroxyl-terminated silicone oil, 10-20 parts of a hydroxyl organic phosphorus compound and 0.1-2 parts of a catalyst. The curing agent has the following advantages: (1) the flame retardance of the epoxy resin curing agent is improved (the limit oxygen index of epoxy resin can reach 33.6%, and the vertical combustion (UL94) level can reach V-0 level), and meanwhile, the impact strength of the epoxy resin is remarkably improved; (2) the common defects of migration, moisture absorption and the like of additive flame retardants are prevented; and (3) the curing agent is used for preparing the epoxy composite material, so that the halogen-free flame retardance of the epoxy resin is realized, and the composite material is endowed with good heat resistance and flexibility.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin materials technology, and in particular to a phosphorus-silicon modified acid anhydride curing agent and a cured resin composition. Background Technology

[0002] Currently, the flammability of most epoxy resin materials in air (their limiting oxygen index (LOI) is below 23%) poses a significant safety hazard during use. Therefore, improving the flame retardant properties of epoxy resin materials has become an urgent problem to be solved. Halogenated flame retardants are commonly used in the market to improve the flame retardancy of epoxy resins; however, halogenated substances release toxic and corrosive gases when burning, which are extremely detrimental to human and environmental health. Compounds containing amine groups are highly efficient curing agents and effective flame retardants for epoxy resins. However, in some specific fields, amine curing agents are difficult to meet process requirements. For example, in commonly used pultrusion systems, acid anhydrides with even weaker flame retardant effects are required, making it even more difficult for the epoxy system to be flame retardant. Therefore, finding halogen-free, highly efficient flame retardants is an urgent issue in the current research on epoxy resin flame retardancy. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the first objective of this invention is to provide a phosphorus-silicon modified anhydride curing agent. This invention combines organosilicon and organophosphorus compounds to jointly modify the curing agent, leveraging the synergistic flame-retardant effect of silicon and phosphorus. This solves the problem of low flame retardancy in previous epoxy resins, while also improving the flexibility and heat resistance of the cured product.

[0004] A second objective of the present invention is to provide a cured resin composition that uses the above-mentioned phosphorus-silicon modified anhydride curing agent as a curing agent, and the cured resin composition has excellent flame retardancy, flexibility and heat resistance.

[0005] This invention discloses a phosphorus-silicon modified acid anhydride curing agent, wherein the phosphorus-silicon modified acid anhydride curing agent has the following raw material composition by mass parts: 80-90 parts acid anhydride, 5-20 parts hydroxyl-terminated silicone oil, 10-20 parts hydroxyl organophosphorus compound, and 1-2 parts catalyst.

[0006] The phosphorus-silicon modified anhydride curing agent provided by this invention, under the action of a catalyst, allows terminal hydroxyl silicone oil and hydroxyl organophosphorus compounds to be grafted onto the anhydride to form a phosphorus-silicon modified anhydride curing agent. After the phosphorus-silicon modified anhydride curing agent reacts and cures with the resin, it becomes part of the crosslinking body, which can prevent the migration and precipitation of phosphorus-silicon. At the same time, it exerts the synergistic flame retardant effect of silicon and phosphorus, solving the problem of low flame retardancy of epoxy resins in the past, and improving the flexibility and heat resistance of the cured product.

[0007] The present invention discloses a phosphorus-silicon modified acid anhydride curing agent, the raw material composition of which is as follows by mass: 80-85 parts acid anhydride, 5-20 parts hydroxyl-terminated silicone oil, 10-20 parts hydroxyl organophosphorus compound, and 0.1-2 parts catalyst.

[0008] This invention discloses a phosphorus-silicon modified acid anhydride curing agent, wherein the acid anhydride is selected from at least one of phthalic anhydride, nadic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, dodecenyl succinic anhydride, poly(ethyl octadecanoic acid) anhydride, styrene maleic anhydride, and derivatives thereof.

[0009] In a further preferred embodiment, the anhydride is selected from at least one of hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, and styrene-maleic anhydride, preferably at least one of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride.

[0010] This invention discloses a phosphorus-silicon modified acid anhydride curing agent, wherein the viscosity range of the hydroxyl-terminated silicone oil is 20-200 Cp, and the range of the hydroxyl groups is 20-150 mg KOH / g.

[0011] As a further preferred embodiment, the viscosity of the hydroxyl-terminated silicone oil is in the range of 50-100 cp; the hydroxyl group range is 50-100 mg KOH / g. The molecular weight of the hydroxyl-terminated silicone oil is directly proportional to its viscosity.

[0012] In this invention, the hydroxyl-terminated organosilicon is one or a mixture of Shin-Etsu KF-6000, KF-6001, KF-6002, and KF-6003.

[0013] In this invention, the terminal hydroxyl phosphorus compound is one or a mixture of IOTA 2030-5, IOTA 2030-10, IOTA 2030-20, IOTA 2030-30, IOTA 2030-40 from Anhui Aiyota Silicon Oil Co., Ltd., and H-3667 from Jiangxi Haiduo Chemical Co., Ltd.

[0014] This invention provides a phosphorus-silicon modified acid anhydride curing agent, wherein the catalyst is selected from at least one of tertiary amines and imidazoles.

[0015] Further preferably, the catalyst is selected from at least one of dimethylpropylamine, pyridine, dimethylaminopyridine, dimethylbenzylamine, dimethylaminomethylphenol, and 2-ethylimidazole, and is more preferably at least one of dimethylbenzylamine, dimethylpropylamine, and 2-ethylimidazole.

[0016] This invention discloses a phosphorus-silicon modified acid anhydride curing agent. The preparation method of the phosphorus-silicon modified acid anhydride curing agent is as follows: A hydroxyl-terminated organosilicon and a hydroxyl-terminated phosphorus compound are mixed, heated to 100-120°C, and vacuum dehydrated for 1-3 hours. Then, an acid anhydride and a catalyst are added, the temperature is raised to 100-150°C, and the reaction is carried out for 1-5 hours. The mixture is then cooled to room temperature, and the resulting product is the phosphorus-silicon modified acid anhydride curing agent. In this invention, the optimal reaction effect is achieved by first mixing and dehydrating the hydroxyl-terminated organosilicon and the hydroxyl-terminated phosphorus compound before adding the acid anhydride and catalyst.

[0017] The present invention discloses a curing resin composition comprising bisphenol A type epoxy resin and phosphorus-silicon modified acid anhydride curing agent, wherein, by mass parts, the bisphenol A type epoxy resin comprises 80-100 parts and the phosphorus-silicon modified acid anhydride curing agent comprises 80-120 parts.

[0018] Preferably, the bisphenol A type epoxy resin is of type CYD-128.

[0019] The phosphorus-silicon modified anhydride curing agent provided in this invention can be used as a flame-retardant toughening agent. Using bisphenol A type epoxy resin as raw material, the cured resin composition obtained under the above formulation can achieve a limiting oxygen index of 33.6%, a vertical burning (UL94) rating of V-0, and an impact strength of 50-80 kJ / m². 2 .

[0020] In actual operation, before use, the curing resin composition needs to be prepared according to the preparation method in this invention to obtain the phosphorus-silicon modified acid anhydride curing agent, and then react with the epoxy resin to form a cured product. The advantage of doing so is that the hydroxyl silicone oil and hydroxyl organophosphorus compounds are embedded in the acid anhydride molecules after reacting with the acid anhydride, and have good compatibility with the epoxy resin. The intrinsic flame retardant and toughening effects of the cured product can be well exerted.

[0021] The beneficial effects of this invention are:

[0022] The production method of the phosphorus-silicon modified acid anhydride curing agent of the present invention is simple, with a synthesis rate of 100%, and no toxic gas or waste liquid emissions, making it environmentally friendly.

[0023] Organophosphorus flame retardants generate highly dehydrating polyphosphoric acid, which rapidly dehydrates and carbonizes oxygen-containing organic matter to form a dense, three-dimensional structure of viscous, non-volatile carbides that cover the surface of the combustible material. This reduces the generation of flammable substances and hinders the diffusion of oxygen to the reaction zone, resulting in an environmentally friendly flame-retardant effect with less smoke, less toxicity, and less corrosive gas generation.

[0024] When hydroxyl silicone oil and hydroxyl organophosphorus are directly applied to epoxy resin, due to the lack of oleophilic segments in their molecular structure, they will migrate to the surface of the cured product after the epoxy resin is cured, causing the surface of the cured product to become sticky and failing to achieve the flame retardant and toughening effect after curing. This invention uses acid anhydride to modify hydroxyl silicon-phosphorus, introducing silicon-phosphorus elements into the acid anhydride through hydroxyl groups. Since they can participate in the curing reaction, the intrinsic flame retardant and toughening effects are achieved. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1

[0027] According to the proportions in Table 1, different proportions of raw materials were added to the following reactions:

[0028] In a 500ml four-necked flask equipped with a nitrogen inlet device, a reflux condenser, a thermometer, and a mechanical stirrer, terminal hydroxyl organosilicon and terminal hydroxyl phosphorus compounds were added. The mixture was heated to 110°C and vacuum dehydrated for 2 hours. Then, acid anhydride and catalyst were added according to the proportions in Table 1, the temperature was raised to 120°C, and the reaction was carried out for 3 hours. After cooling to room temperature, the product was discharged to obtain the silicon-phosphorus modified acid anhydride curing agent. The catalyst was dimethylbenzylamine, and the catalyst was added in a ratio of 1 part.

[0029] The cured properties of products from groups 1 to 11 in Example 1 of the curable epoxy resin system are evaluated as follows. The epoxy resin used is CYD128 (bisphenol A diglycidyl ether), and by mass parts: 100 parts epoxy resin and 95 parts silicon-phosphorus modified anhydride curing agent.

[0030] The analysis items include glass transition temperature (tg), flame retardancy rating, and impact strength.

[0031] Table 1 Properties of Silicon-Phosphorus Modified Methyltetrahydrophthalic Anhydride and its Resin Cured Products

[0032]

[0033] As can be seen from the data in Table 1, the flame retardancy of the cured product can only reach V0 when the content of IOTA 2030-10 reaches more than 10 parts. However, when IOTA 2030-10 is used alone, the Tg and impact strength decrease significantly. When KF6000 is introduced, the impact strength of the cured product is significantly improved. As can be seen from Example 1, the optimal ratio of acid anhydride: hydroxyl silicone oil: terminal hydroxyl phosphorus compound is 80-85: 5~20: 10~20.

[0034] Example 2

[0035] According to the proportions in Table 2, different proportions of raw materials were added to the following reactions:

[0036] In a 500ml four-necked flask equipped with a nitrogen inlet device, a reflux condenser, a thermometer, and a mechanical stirrer, terminal hydroxyl organosilicon and terminal hydroxyl phosphorus compounds were added. The mixture was heated to 120°C and vacuum dehydrated for 1 hour. Then, acid anhydride and catalyst were added according to the proportions in Table 1, the temperature was raised to 120°C, and the reaction was carried out for 2 hours. After cooling to room temperature, the product was discharged to obtain the silicon-phosphorus modified acid anhydride curing agent. The catalyst was dimethylpropylamine, and the amount of catalyst added was 1 part.

[0037] The cured properties of products from groups 1 to 11 in Example 2 of the curable epoxy resin system are evaluated as follows. The epoxy resin used is CYD128 (bisphenol A diglycidyl ether), and by mass parts: 100 parts epoxy resin and 95 parts silicon-phosphorus modified anhydride curing agent.

[0038] The analysis items include glass transition temperature (tg), flame retardancy rating, and impact strength.

[0039] Table 2 Properties of Silicon-Phosphorus Modified Methylhexahydrophthalic Anhydride and its Resin Cured Products

[0040]

[0041] As can be seen from the data in Table 2, the flame retardancy of the cured product can only reach V0 when the content of IOTA 2030-40 reaches more than 10 parts. However, when IOTA 2030-40 is used alone, the Tg and impact strength decrease significantly. When KF6001 is introduced, the impact strength of the cured product is significantly improved. As can be seen from Example 2, the optimal ratio of acid anhydride: hydroxyl silicone oil: terminal hydroxyl phosphorus compound is 80-85: 5~20: 10~20.

[0042] Example 3

[0043] According to the proportions in Table 3, different proportions of raw materials were added to the following reactions:

[0044] In a 500ml four-necked flask equipped with a nitrogen inlet device, a reflux condenser, a thermometer, and a mechanical stirrer, hydroxyl-terminated organosilicon and hydroxyl-terminated phosphorus compounds were added, heated to 100°C, and vacuum dehydrated for 3 hours. Then, acid anhydride and catalyst in the proportions shown in Table 1 were added, the temperature was raised to 100°C, the reaction was carried out for 5 hours, cooled to room temperature, and the product was discharged to obtain the silicon-phosphorus modified acid anhydride curing agent. The catalyst was 2-ethylimidazole, and the amount of catalyst added was 2 parts.

[0045] The cured properties of products from groups 1 to 11 in Example 3 of the curable epoxy resin system are evaluated as follows. The epoxy resin used is CYD128 (bisphenol A diglycidyl ether), and by mass parts: 90 parts epoxy resin and 110 parts silicon-phosphorus modified anhydride curing agent.

[0046] The analysis items include glass transition temperature (tg), flame retardancy rating, and impact strength.

[0047] Table 3. Properties of Silicon-Phosphorus Modified Methylnadic Anhydride and its Resin Cured Products

[0048]

[0049] As can be seen from the data in Table 3, the flame retardancy of the cured product can only reach V0 when the content of IOTA 2030-20 reaches more than 10 parts. However, when IOTA 2030-20 is used alone, the Tg and impact strength decrease significantly. When KF6003 is introduced, the impact strength of the cured product is significantly improved. As can be seen from Example 3, the optimal ratio of acid anhydride: hydroxyl silicone oil: terminal hydroxyl phosphorus compound is 80-85: 5~20: 10~20.

[0050] This invention provides a phosphorus-silicon modified acid anhydride curing agent and its curing resin composition. By combining organosilicon and organophosphorus compounds to jointly modify the curing agent, the synergistic flame-retardant effect of silicon and phosphorus is achieved. The resulting cured product exhibits good flame retardancy and also improves the flexibility and heat resistance of the cured product.

[0051] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art based on the above description should be included within the scope of protection of the present invention. The scope of protection of the present invention shall be defined by the appended claims.

Claims

1. A phosphorus-silicon modified acid anhydride curing agent, characterized in that: The phosphorus-silicon modified acid anhydride curing agent has the following raw material composition by mass: 80-90 parts acid anhydride, 5-20 parts hydroxyl-terminated silicone oil, 10-20 parts hydroxyl organophosphorus compound, and 0.1-2 parts catalyst.

2. The phosphorus-silicon modified acid anhydride curing agent according to claim 1, characterized in that: The phosphorus-silicon modified acid anhydride curing agent has the following raw material composition by mass: 80-85 parts acid anhydride, 5-20 parts hydroxyl-terminated silicone oil, 10-20 parts hydroxyl organophosphorus compound, and 1-2 parts catalyst.

3. A phosphorus-silicon modified anhydride curing agent according to claim 1 or 2, characterized in that: The anhydride is selected from at least one of phthalic anhydride, nadic anhydride, trimellitic anhydride, pyromellitic anhydride, benzophenone tetracarboxylic anhydride, dodecenyl succinic anhydride, poly(ethyl octadecanoic acid) anhydride, styrene maleic anhydride, and derivatives thereof.

4. The phosphorus-silicon modified acid anhydride curing agent according to claim 3, characterized in that: The anhydride is selected from at least one of hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, and styrene-maleic anhydride.

5. A phosphorus-silicon modified acid anhydride curing agent according to claim 1 or 2, characterized in that: The viscosity range of the hydroxyl-terminated silicone oil is 20–200 Cp, and the range of hydroxyl groups is 20–150 mg KOH / g.

6. The phosphorus-silicon modified acid anhydride curing agent according to claim 5, characterized in that: The viscosity range of the hydroxyl-terminated silicone oil is 50-100 cp, and the range of hydroxyl groups is 50-100 mg KOH / g.

7. A phosphorus-silicon modified acid anhydride curing agent according to claim 1 or 2, characterized in that: The catalyst is selected from at least one of tertiary amines and imidazoles.

8. A phosphorus-silicon modified anhydride curing agent according to claim 1 or 2, characterized in that: The preparation method of the phosphorus-silicon modified acid anhydride curing agent is as follows: hydroxyl-terminated organosilicon and hydroxyl-terminated phosphorus compound are mixed, heated to 100-120℃, and vacuum dehydrated for 1-3 hours. Then, acid anhydride and catalyst are added, the temperature is raised to 100-150℃, the reaction is carried out for 1-5 hours, and the mixture is cooled to room temperature. The silicon-phosphorus modified acid anhydride curing agent is then obtained by discharging the material.

9. A cured resin composition, characterized in that: It is composed of bisphenol A type epoxy resin and the phosphorus-silicon modified acid anhydride curing agent according to any one of claims 1-8, wherein, by mass parts, the bisphenol A type epoxy resin is 80-100 parts and the phosphorus-silicon modified acid anhydride curing agent is 80-120 parts.

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