阅读说明：本技术 一种环氧固化剂及其制备方法，一种环氧树脂组合物及其用途 (Epoxy curing agent and preparation method thereof, epoxy resin composition and application thereof ) 是由 周萌 刘赵兴 曹善健 朱宏达 于 2021-08-10 设计创作，主要内容包括：本发明公开一种环氧固化剂及其制备方法,一种环氧树脂组合物及其用途。所述环氧固化剂的结构式为所述耐候型固化剂的制备原料包括水杨酸酯、醛类化合物和脂环族二胺,该固化剂结构中含有紫外吸收基团,与环氧树脂配合形成均相体系,通过化学键将耐黄变基团引入到交联网络中,避免了物理添加存在的紫外吸收剂迁移问题,该固化剂对波长为290-400nm的紫外线有强烈吸收作用,且对固化体系的性能无明显影响,固化剂的反应活性高,体系后固化温度降低,避免了加热导致的黄变。特别适用于对耐黄变要求较高的LED封装领域。(The invention discloses an epoxy curing agent and a preparation method thereof, and an epoxy resin composition and application thereof. The structural formula of the epoxy curing agent is)

1. An epoxy curing agent, which has a structural formula:

wherein R is₁is-CH₃、 R₂Is H, -CH₃Or,R₃Is composed of

2. A method of preparing the epoxy hardener of claim 1, comprising the steps of:

(1) under the protection of inert gas, salicylic acid ester and alicyclic diamine are uniformly mixed, and the temperature is raised;

(2) adding an aldehyde compound into the product in the step (1) for reaction.

3. The method according to claim 2, wherein the salicylate is selected from one or more of methyl salicylate, p-tert butyl salicylate, p-octylphenyl salicylate, bisphenol a disalicylate, and menthyl salicylate, preferably p-tert butyl salicylate.

4. The process according to claim 2, characterized in that said cycloaliphatic diamine is selected from the group consisting of 1, 2-cyclohexanediamine, 4 '-dicyclohexylmethanediamine, preferably 4, 4' -dicyclohexylmethanediamine.

5. The method according to claim 2, wherein the aldehyde compound is one or more selected from the group consisting of 5 to 40 wt% of an aqueous formaldehyde solution, acetaldehyde and benzaldehyde, preferably acetaldehyde.

6. The method according to claim 2, wherein in the step (1), the molar ratio of the salicylate to the alicyclic diamine is 1 (0.9-1.1), preferably 1: 0.95-1: 1.05; in the step (2), the molar ratio of the aldehyde compound to the alicyclic diamine is 1 (0.9 to 1.1), preferably 1:0.95 to 1: 1.05.

7. An epoxy resin composition comprising the following components:

(A) the method comprises the following steps Epoxy resin, diluent and flatting agent;

(B) the method comprises the following steps The epoxy hardener of claim 1, a defoamer;

the mass ratio of the component (A) to the component (B) is (1-10): 1, preferably (2-8): 1.

8. The epoxy resin composition of claim 7, wherein the (A) component is prepared from raw materials comprising, based on the weight of (A) component:

55-78 wt% of epoxy resin; preferably 60-75 wt%;

6-30 wt% of a diluent; preferably 10 to 25 wt%;

1 to 17 wt% of a leveling agent, preferably 11 to 15 wt%.

9. The epoxy resin composition of claim 7, wherein the (B) component is preferably prepared from raw materials comprising, based on the weight of (B) component:

70-98 wt% of the epoxy curing agent;

2-30 wt% of defoaming agent.

10. Use of the epoxy resin composition according to any one of claims 7 to 9 for stone glues, overprint varnishes, LED packaging, joint polishes, decorative glues.

Technical Field

The invention belongs to the field of epoxy resin, and particularly relates to a weather-resistant epoxy resin curing agent, an epoxy resin composition and application thereof.

Background

Epoxy resin is a thermosetting resin with excellent comprehensive performance, and is widely applied to various fields such as electronic potting materials, adhesives, advanced composite material matrixes and the like, wherein the fields such as LEDs, optical disk substrates, prisms, ornaments and the like have higher requirements on optical performance, and the epoxy resin needs to have the characteristics of high transparency and yellowing resistance so as to ensure the light transmittance and high refractivity of devices.

However, the epoxy resin material is sensitive to light, and is easy to undergo a photochemical reaction, so that the epoxy resin is degraded, the resin material is yellowed, and the mechanical property is reduced. In particular, in the field of adhesives for specific applications and the like, the restriction on product color is strict, and thus the improvement of yellowing resistance of epoxy resins has become a major research topic. The yellowing of epoxy articles is caused by a variety of factors, such as: aromatic epoxy resin bisphenol A structure is easy to oxidize to generate carbonyl to form a yellow group; secondly, free amine in the amine curing agent is directly polymerized with epoxy resin, so that the temperature is increased in a local range, and the yellowing is accelerated; ③ the tertiary amine accelerant and the nonyl phenol accelerant are easy to change color under the irradiation of hot oxygen and U V; fourthly, the temperature in the reaction process is too high, and residual impurities and metal catalysts in the system can cause yellowing.

The common curing agents for the epoxy resin mainly comprise amines and acid anhydrides, the post-curing temperature of the acid anhydride curing agent is high, the post-curing temperature of the acid anhydride curing agent is easy to cause yellowing of a benzene ring structure in the epoxy resin, low molecular amines capable of being cured at room temperature, such as diethylenetriamine, have strong odor and toxicity and are easy to be oxidized and yellowed by air, and the alicyclic amine curing agent has good heat resistance and air oxidation discoloration performance, but can still be obviously yellowed under long-term outdoor illumination.

Ultraviolet rays are another important factor causing the oxidative yellowing of an epoxy system, mainly come from sunlight, and an antioxidant and an ultraviolet absorbent are added, so that the method is an effective solution. Particularly, when the product of the epoxy resin used outdoors is produced, a certain amount of antioxidant and ultraviolet absorbent are added, so that ultraviolet can be effectively absorbed, and yellowing is delayed. However, the antioxidant and the ultraviolet absorber are usually added physically, and the migration to the surface of the product and the uneven distribution in the product can exist in the curing process, so that the yellowing resistance of the product is reduced.

CN 1106988649 discloses an anti-ultraviolet flame-retardant epoxy resin curing agent, which can uniformly and firmly introduce an ultraviolet absorbing active group o-hydroxybenzophenone and a flame-retardant active group DOPO into a cured resin material through chemical bonds in a reaction process of curing the epoxy resin material, and simultaneously endow the cured epoxy resin material with excellent anti-ultraviolet performance and flame retardancy, but the curing agent has low reaction activity, can be cured under a high temperature condition, and can cause thermal aging and yellowing of the material. CN106189689A discloses a curing agent adopting a mixed system of a polyamide curing agent and hydrogenated cardanol modified phenolic aldehyde amine.

The factors are comprehensively considered, a weather-resistant epoxy curing agent needs to be found, an ultraviolet absorption group is introduced into a curing agent structure through a chemical reaction, so that the curing agent can strongly absorb ultraviolet rays with the wavelength of 290-400nm, a homogeneous system can be formed after the curing agent reacts with epoxy resin at room temperature, and the performance of a cured product is not obviously influenced.

Disclosure of Invention

The invention provides an epoxy curing agent and a preparation method thereof, an epoxy resin composition and application thereof. The curing agent structure contains ultraviolet absorption groups, a homogeneous system is formed by matching with epoxy resin, yellowing resistant groups are introduced into a cross-linked network through chemical bonds, the problem of ultraviolet absorbent migration in physical addition is avoided, the curing agent has a strong absorption effect on ultraviolet rays with the wavelength of 290-400nm, and the performance of the curing system is not obviously influenced. The curing agent has high reaction activity, the post-curing temperature of the system is reduced, and yellowing caused by heating is avoided.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

an epoxy curing agent, which has a structural formula:

wherein R is₁is-CH₃、 R₂Is H, -CH₃Or,R₃Is composed of

In the invention, the preparation method of the epoxy curing agent is also provided, and comprises the following steps:

(1) under the protection of inert gas, salicylic acid ester and alicyclic diamine are uniformly mixed, and the temperature is raised;

(2) adding an aldehyde compound into the product in the step (1) for reaction.

The salicylate is one or more selected from methyl salicylate, p-tert-butyl salicylate, p-octylphenyl salicylate, bisphenol A salicylate and menthyl salicylate, and is preferably p-tert-butyl salicylate.

The cycloaliphatic diamine of the present invention is selected from the group consisting of 1, 2-cyclohexanediamine and 4,4 '-dicyclohexylmethanediamine, preferably 4, 4' -dicyclohexylmethanediamine.

In the step (1) of the present invention, the molar ratio of the salicylate to the alicyclic diamine is 1 (0.9 to 1.1), preferably 1:0.95 to 1: 1.05.

In the step (1), the temperature is raised to 60-90 ℃, preferably 75-85 ℃.

In the step (2), the reaction temperature is 70-100 ℃, preferably 80-90 ℃, and the reaction time is 2-4 hours, preferably 2.5-3.5 hours.

In the step (2) of the present invention, the molar ratio of the aldehyde compound to the alicyclic diamine is 1 (0.9 to 1.1), preferably 1:0.95 to 1: 1.05.

The aldehyde compound is selected from one or more of 5-40 wt% of formaldehyde aqueous solution, acetaldehyde and benzaldehyde, and acetaldehyde is preferred.

The invention also provides application of the epoxy curing agent in preparation of epoxy resin.

The invention provides an epoxy resin composition, which comprises the following components:

(A) the method comprises the following steps Epoxy resin, diluent and flatting agent;

(B) the method comprises the following steps The epoxy curing agent and the defoaming agent;

the mass ratio of the component (A) to the component (B) is (1-10): 1, preferably (2-8): 1.

In the epoxy resin composition of the present invention, the component (a) is preferably prepared from raw materials comprising, based on the weight of the component (a):

55-78 wt% of epoxy resin; preferably 60-75 wt%;

6-30 wt% of a diluent; preferably 10 to 25 wt%;

1 to 17 wt% of a leveling agent, preferably 11 to 15 wt%.

In a preferred embodiment of the present invention, the preparation method of the component a comprises the following steps: adding epoxy resin into mixing equipment, heating to 35-70 ℃, preferably 50-60 ℃, adding a diluent and a flatting agent, heating to 40-65 ℃, preferably 50-60 ℃, stirring for 1-5 hours, preferably 2-4 hours, uniformly mixing and standing.

In the component (A), the epoxy resin is one or more of bisphenol A type epoxy resin and bisphenol F type epoxy resin; one or more of bisphenol A type epoxy resin and bisphenol F type epoxy resin with the epoxy value of 0.1-0.65 and liquid at room temperature are preferably selected; more preferably bisphenol A epoxy resin with an epoxy value of 0.1-0.65 and liquid at room temperature; including but not limited to one or more of E-44, E-51, E-54, and the like.

The diluent is one or more of a reactive diluent and a non-reactive diluent; preferred diluents include, but are not limited to, one or more of alkyl glycidyl ethers having a molecular backbone of C12-C14, butyl glycidyl ether, benzyl glycidyl ether, butanediol diglycidyl ether, 1, 6-hexanediol diglycidyl ether, 1, 2-cyclohexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, benzyl alcohol, phenethyl alcohol, nonylphenol, propylene carbonate, trimethylolpropane triacrylate, diisopropanol methyl ether, toluene, xylene, and the like.

The leveling agent is one or more of polyacrylate and modified organic silicon, and preferably one or more of Bick chemical BYK-388, BYK-320, BYK-358N and BYK-392.

In the epoxy resin composition of the present invention, the component (B) is preferably prepared from raw materials comprising the following components, based on the weight of the component (B):

70-98 wt% of the epoxy curing agent;

2-30 wt% of defoaming agent.

In a preferred embodiment of the present invention, the preparation method of the (B) component comprises the steps of: and adding the epoxy curing agent and the defoaming agent into a reaction kettle, keeping the temperature of the reaction kettle at 30-60 ℃, preferably 35-55 ℃, stirring for 1-5 hours, preferably 2-4 hours, uniformly mixing, and standing.

In the present invention, the preparation method of the epoxy resin composition comprises the steps of: mixing the component (A) and the component (B) uniformly, defoaming, and curing in a carrier or a mold.

In some specific embodiments of the preparation method of the epoxy resin composition, the component (A) and the component (B) are uniformly mixed and then are kept stand for 15-60 min, preferably 20-45 min; the curing temperature is usually 25-55 ℃, preferably 30-45 ℃, and the curing time is 1-5 hours, preferably 2-4 hours.

The reaction process for preparing the epoxy curing agent is schematically illustrated by taking p-tert-butyl benzoate salicylate, 4' -dicyclohexylmethane diamine and acetaldehyde as examples:

according to the invention, the epoxy curing agent contains an ultraviolet absorbing group in the structure, the ultraviolet absorbing group is matched with epoxy resin to form a homogeneous system, and a yellowing resistant group is introduced into a cross-linked network through a chemical bond, so that the problem of ultraviolet absorber migration in physical addition is avoided, the curing agent has a strong absorption effect on ultraviolet rays with the wavelength of 290-400nm, and the curing agent has no influence on the performance of the curing system and has excellent weather resistance.

The curing agent of the invention realizes weather resistance through the following reactions:

the epoxy resin composition can be applied to stone glue, finishing varnish, LED packaging, seam beautifying agent, ornament glue and the like, and is particularly suitable for the field of LED packaging with higher yellowing resistance requirements.

The invention has the beneficial effects that:

(1) an ultraviolet absorbing group is introduced into the curing agent through a chemical reaction, and the ultraviolet absorbing agent can be crosslinked with the epoxy resin, so that the problem of auxiliary agent migration in physical addition is avoided;

(2) the phenolic amine structure in the epoxy curing agent can improve the reaction activity of the curing agent, reduce the post-curing temperature of the system and avoid yellowing caused by heating;

(3) the epoxy curing agent has simple preparation process and strong practicability.

Detailed Description

The test method of the main performance and indexes in the embodiment comprises the following steps:

gel time: GB/T12007.7-1989;

the artificial aging test method comprises the following steps: GB/1865-2009;

the color measurement method comprises the following steps: GB/T22295-.

Example 1

Preparation of weather-resistant epoxy curing agent:

(1) under the protection of inert gas, uniformly mixing methyl salicylate and 1, 2-cyclohexanediamine in a molar ratio of 1:0.95, and heating to 75 ℃.

(2) Adding 35% formaldehyde solution in the step (1), heating to 80 ℃, reacting for 3.5h, wherein the molar ratio of the formaldehyde solution to the 1, 2-cyclohexanediamine is 1:0.95, and obtaining the weather-resistant epoxy curing agent.

The structure of the curing agent is as follows:

by FT-IR infrared analysis, at 2950cm^-1Form a secondary amine group absorption peak at 1460cm^-1Is the stretching shock absorption peak of methylene.

Preparation of epoxy resin composition:

preparation of component A: 70g of bisphenol A diglycidyl ether (epoxy value is 0.51), 19g of 1, 4-butanediol diglycidyl ether and 11g of BYK-388 leveling agent are mixed uniformly and then are stood.

Preparation of the component B: 70g of the curing agent prepared in the example and 30g of BYK066N were added to a reaction kettle, mixed uniformly and then allowed to stand.

Mixing the component A and the component B according to the mass ratio of 8: 1, standing for 45min after uniformly mixing, and heating to 45 ℃ for curing for 2 h.

The gel time of the weather-resistant curing agent prepared in the embodiment at 25 ℃ is 45min/100g, and the color number of a sample placed in a 50w ultraviolet box for 300h is 2.

The epoxy resin composition can be used for LED light bar glue.

Example 2

Preparation of weather-resistant epoxy curing agent:

(1) under the protection of inert gas, p-tert-butyl phenyl salicylate and 1, 2-cyclohexanediamine in the molar ratio of 1:1.05 are mixed uniformly, and the temperature is raised to 85 ℃.

(2) Adding formaldehyde into the step (1), heating to 90 ℃, and reacting for 2.5 hours, wherein the molar ratio of the formaldehyde to the cyclohexanediamine is 1:1.05, so as to obtain the weather-resistant epoxy curing agent.

The structure of the curing agent is as follows:

by FT-IR infrared analysis, at 2890cm^-1Form an absorption peak of secondary amine groups at 1475cm^-1Is the stretching shock absorption peak of methylene.

Preparation of epoxy resin composition:

preparation of component A: 73g of bisphenol F diglycidyl ether (epoxy value of 0.51), 15g of 1, 6-hexanediol diglycidyl ether and 12g of BYK-320 leveling agent were mixed uniformly and then left to stand.

Preparation of the component B: 80g of the curing agent prepared in the example and 20g of BYKA530 were added to a reaction kettle and mixed uniformly, followed by standing.

Mixing the component A and the component B according to the mass ratio of 2: 1, standing for 20min after uniformly mixing, and heating to 30 ℃ for curing for 4 h.

The gel time of the weather-resistant curing agent prepared in the embodiment at 25 ℃ is 27min/100g, and the color number of a sample placed in a 50w ultraviolet box for 300h is 1.

The epoxy resin composition can be used for ornament glue.

Example 3

Preparation of weather-resistant epoxy curing agent:

(1) under the protection of inert gas, p-octylphenyl salicylate and 4', 4-dicyclohexylmethane diamine in a molar ratio of 1:1 are uniformly mixed, and the temperature is raised to 80 ℃.

(2) Adding benzaldehyde in the step (1), heating to 85 ℃, and reacting for 3 hours, wherein the molar ratio of the benzaldehyde to 4 ', 4' -dicyclohexylmethane diamine is 1:1, so as to obtain the weather-resistant epoxy curing agent.

The structure of the curing agent is as follows:

FT-IR infrared analysis at 2900cm^-1Form an absorption peak of secondary amine group at 1450cm^-1Is the stretching shock absorption peak of methylene.

Preparation of epoxy resin composition

Preparation of component A: 75g of bisphenol A diglycidyl ether (epoxy value is 0.51), 14g of 1, 6-hexanediol diglycidyl ether and 11g of BYK-320 leveling agent are mixed uniformly and then are stood.

Preparation of the component B: 98g of the curing agent prepared in this example and 2g of Haimines 6800 were added to a reaction vessel and mixed uniformly and then allowed to stand.

Mixing the component A and the component B according to a mass ratio of 4: 1, standing for 30min after uniformly mixing, and heating to 35 ℃ for curing for 3 h.

The gel time of the weather-resistant curing agent prepared in the embodiment at 25 ℃ is 31min/100g, and the color number of a sample placed in a 50w ultraviolet box for 300h is 2.

The epoxy resin composition can be used for floor finishing varnish.

Comparative example 4

Preparation of epoxy resin composition:

preparation of component A: 70g of bisphenol A diglycidyl ether (epoxy value is 0.51), 14g of 1, 4-butanediol diglycidyl ether and 11g of BYK-388 leveling agent are mixed uniformly and then are stood.

Preparation of the component B: 70g of 1, 2-cyclohexanediamine and 30g of BYK-066N are added into a reaction kettle, mixed uniformly and then kept stand.

Mixing the component A and the component B according to the mass ratio of 5: 1, standing for 30min after uniformly mixing, and heating to 35 ℃ for curing for 3 h.

The gel time of the weather-resistant curing agent prepared in the embodiment at 25 ℃ is 131min/100g, and the color number of a sample placed in a 50w ultraviolet box for 300h is 9.

Comparative example 5

Preparation of phenolic aldehyde amine epoxy curing agent without ultraviolet absorbing group:

(1) under the protection of inert gas, phenol and 1, 2-cyclohexanediamine are uniformly mixed according to the molar ratio of 1:0.95, and the temperature is raised to 75 ℃.

(2) Adding 35% formaldehyde solution in the step (1), heating to 80 ℃, reacting for 3.5h, wherein the molar ratio of the formaldehyde solution to the 1, 2-cyclohexanediamine is 1:0.95, and obtaining the phenolic aldehyde amine epoxy curing agent.

Preparation of epoxy resin composition:

preparation of component A: 70g of bisphenol A diglycidyl ether (epoxy value is 0.51), 19g of 1, 4-butanediol diglycidyl ether and 11g of BYK-388 leveling agent are mixed uniformly and then are stood.

Preparation of the component B: 68g of the curing agent prepared in the example, 30g of BYK066N and 2g of methyl salicylate are added into a reaction kettle, mixed uniformly and then placed still.

Mixing the component A and the component B according to the mass ratio of 8: 1, standing for 45min after uniformly mixing, and heating to 45 ℃ for curing for 2 h.

The gel time of the weather-resistant curing agent prepared in the embodiment at 25 ℃ is 37min/100g, and the color number of a sample placed in a 50w ultraviolet box for 300h is 6.