CN1958639A - Solidifying agent for aqueous epoxy resin, and preparation method - Google Patents

Abstract

The invention discloses a water-based epoxy resin curing agent and a preparation method thereof. The method is to make a water-based epoxy resin curing agent through the condensation reaction of epoxy resin and polyether diol, the addition and modification of polyethylene polyamine, capping and salt formation, and the capping is made of acrylonitrile It is mixed with the polyethylene polyamine modified product obtained by addition modification according to the molar ratio of nitrile group and primary amine hydrogen in a ratio of 1.1 to 1.2:1.0, and reacted at a temperature of 65 to 70°C for 1.5 to 2.0 hours. The solid content of the prepared water-based epoxy resin curing agent is 45-50%, the range of amine value is 290-500, and the viscosity is 8.0ps-14ps. The invention has moderate amine equivalent, can emulsify and cure low-molecular-weight epoxy resin, and is easy to synthesize; can cure epoxy resin at normal temperature, is non-toxic and harmless, and has no volatile organic solvent. The curing agent prepared by the invention can greatly reduce the irritation of the modified polyamine to the skin and basically eliminate the volatile odor.

Description

A kind of waterborne epoxy resin curing agent and preparation method thereof

technical field

The invention relates to the technical field of curing agents, in particular to a water-based epoxy resin curing agent and a preparation method thereof.

Background technique

Polyamine epoxy resin curing agents are divided into two types: single polyamine and modified amine, and single polyamine is divided into four types: straight chain aliphatic amine, polyamide, alicyclic amine and aromatic amine. Linear fatty polyamine has the characteristics of fast curing speed, excellent hue, high viscosity, high hardness of cured paint film, good gloss, good adhesion performance, excellent acid and alkali resistance, etc. But there are also inherent shortcomings, such as high volatility, high toxicity, short pot life, strict ratio requirements, etc.; it is easy to react with carbon dioxide in the air to form amine carbonate, which makes the paint film white and incompletely cured. In order to overcome these shortcomings, it must be further modified to obtain an amine curing agent that is non-toxic or low-toxic, can be cured at room temperature, and has strict ratio requirements.

The invention patent (publication number is CN 1415680A) discloses a polyamine-epoxy ring resin adduct, and discloses that the modified curing agent is obtained by blocking the primary amine with butyl glycidyl ether. The molecular weight of butyl glycidyl ether is 130, and the amine hydrogen equivalent of the prepared modified curing agent is relatively large. The greater the amine hydrogen equivalent of the curing agent, the greater the amount of the curing agent used when the epoxy resin is cured in proportion, so that the introduction of more hydrophilic group polyether chains will reduce the water resistance of the cured coating, and Construction will also be inconvenient. It was also used α-methacrylic acid as a capping agent. And α-methacrylic acid is easy to self-polymerize.

Contents of the invention

The purpose of the present invention is to propose an environment-friendly preparation method of a water-based epoxy resin curing agent capable of simultaneously emulsifying and curing epoxy resin and having excellent performance.

Another object of the present invention is to provide the water-based epoxy resin curing agent prepared by the above method.

The purpose of the present invention is through the following technical solutions.

A preparation method of waterborne epoxy resin curing agent, comprising the following steps and process conditions:

(1) Condensation reaction between epoxy resin and polyether diol: a condensation product is generated from epoxy resin and polyether diol under the catalysis of zinc chloride, and the molar ratio of epoxy resin to polyether diol is 2.2 ～2.0:1.0, the reaction temperature is controlled at 90～100° C., and the reaction time is 6～8 hours.

Since the polarity of epoxy resin is closely related to the polarity of water, and its HLB (lipophilic-hydrophilic-water balance value) is 3, it is difficult to emulsify it with pure water. If an emulsifier is added, the emulsifier molecules will remain in the cured coating film, which will have a negative impact on its performance. The present invention introduces a nonionic surfactant into the polyethylene polyamine chain, so that it has good emulsifying ability for epoxy resin. This nonionic surfactant is formed by the reaction of epoxy resin and polyethylene glycol under the catalysis of zinc chloride. The obtained condensate is milky white viscous liquid or solid at room temperature according to the molecular weight of polyethylene glycol. Different from the external emulsifier, the nonionic surfactant obtained by the reaction of epoxy resin and polyethylene glycol has epoxy groups at both ends, which can participate in the curing reaction of epoxy resin and now become a part of the coating film. Less affected.

(2) Addition modification to polyethylene polyamine: mix the condensation product of step (1) with low molecular weight epoxy resin, the molar equivalent ratio of the epoxy group content in the condensation product to the epoxy group content in the low molecular weight epoxy resin It is 1.0～1.2/2.0, and mixed with polyethylene polyamine dissolved in water, and the reaction time is 2～3 hours at a temperature of 65～70°C; in the mixture, the molar amount of amine hydrogen is equal to the total molar epoxy group The amount ratio is 6.2-6.4:1.0, and the water content is 20%-30%.

React the prepared nonionic surfactant with polyethylene polyamine to add polyether segments to the molecular chain of polyethylene polyamine. In order to obtain a curing agent with application value, chain extension is carried out with epoxy resin. A curing agent with a large molecular weight is obtained. Due to the introduction of the epoxy segment, the compatibility between the curing agent and the epoxy resin is also increased. Because a large amount of heat of reaction will be released during the addition reaction. In order to avoid gelation, it is necessary to add water as a cooling medium. However, because the polarity of water is closely related to the polarity of epoxy resin, in order to prevent the added epoxy resin from being dispersed unevenly when the water content is too high, it will be precipitated in the form of droplets, and the reaction will proceed on the surface of the droplets. The oxygen resin concentration is too high, resulting in curing crosslinking. Therefore, the amount of water added is preferably 20-30%.

(3) Capping: mix acrylonitrile with the modified polyethylene polyamine obtained in step (2) at a molar ratio of 1.1-1.2:1.0, and react at a temperature of 65-70° C. for 1.5-2.0 hours. Since the reaction is an exothermic reaction, it is necessary to slowly add acrylonitrile dropwise, and at the same time take measures to dissipate heat.

(4) Salt formation: For the end-capped product, a monobasic organic acid is used to form a salt; the equivalent ratio of the organic acid to the remaining amine hydrogen is 1.0:4.5-5.0, the reaction temperature is 65-70°C, and the reaction time is 1.0-5. After 1.5 hours, after the reaction is over, add water to obtain a water-based epoxy resin curing agent with a solid content of 45-50%.

The water-based epoxy resin curing agent prepared by the above method has a solid content of 45-50%, an amine value range of 290-500, and a viscosity of 8.0ps-14ps.

The invention introduces the polyether chain segment in the polyethylene glycol into the curing agent, which can function as a nonionic surfactant and emulsify the low molecular weight epoxy resin. At the same time, the nitrile ethylation reaction between acrylonitrile and aliphatic polyamine greatly improves the compatibility of curing agent and epoxy resin and reduces the bad irritation like other modified aliphatic polyamine curing agents.

Compared with the prior art, the present invention has the following advantages:

1. The amine hydrogen equivalent of the modified curing agent obtained is less, and when curing the epoxy resin of the same weight, the consumption of the curing agent of the present invention is relatively higher than that of other modified curing agents obtained by end-blocking with ester glycidyl ether Less, the introduction of hydrophilic polyether chains is less, the water resistance is improved, and the construction is convenient.

2. Good compatibility with epoxy resin. After mixing with low molecular weight epoxy resin for 5 minutes, there is no or only a very small amount of epoxy droplets on the liquid surface of the mixture, indicating that the two can be well mixed and compatible. .

3. Compared with most other modified aliphatic polyamines, the curing agent of the present invention can greatly reduce the irritation of modified polyamines to the skin, and basically eliminate its volatile odor.

Detailed ways

In order to better understand the present invention, the present invention will be further described in detail below in conjunction with the examples, but the protection scope of the present invention is not limited to the range indicated by the examples.

Example 1

(1) Condensation reaction of epoxy resin and polyether diol.

In a four-neck flask with condensed water and nitrogen protection, put 43 grams of epoxy resin E-51 and 100 grams of polyethylene glycol 2000 into it. The temperature of the flask was raised to 70°C, and the reaction materials were fully mixed evenly under stirring. Then add 2.45 grams of zinc chloride as a catalyst. In the initial stage of the reaction, a large amount of reaction heat will be released. At this time, attention should be paid to opening the condensed water, and at the same time, the flow rate of the protective gas nitrogen should be increased to take away the heat and make it fully dissipate. The temperature was controlled at about 95°C, and the reaction was stirred for 8 hours. Samples were taken to determine the epoxy value.

(2) Addition modification to polyethylene polyamine

Add 48.5 grams of triethylenetetramine to the above four-necked flask (the flask should be cooled to about 50°C first), stir for about 15 minutes, control the temperature at about 65°C, and slowly add 39.2 grams of epoxy resin E -51. In order to prevent the heat of reaction released during the addition from causing gelation, before adding epoxy resin E-51, add 60 ml of water as a heat dissipation medium. After adding E-51 dropwise. The stirring reaction was continued for 3 hours.

(3) capping

Add appropriate amount of distilled water to the adduct obtained above to make the solid content about 75%. After adding water, stir for 30 minutes, and then slowly add 22 g of acrylonitrile dropwise for capping.

The reaction temperature is controlled at about 70°C. The reaction time was 2.0 hours.

(4) into salt

To the material after capping, 16 grams of acetic acid was added to carry out a salt-forming reaction to improve the water solubility of the solution. The reaction temperature was 78°C, and the reaction time was 1.5 hours. After the reaction was finished, 160 grams of water was added to adjust the solid content, and it became a translucent light yellow viscous liquid.

After testing, the solid content is 45%, the amine hydrogen equivalent is 423; the viscosity is about 13ps (25±1℃)

This curing agent has no volatile organic compounds (VOC), which improves environmental performance; it has emulsifying and curing effects on low molecular weight epoxy resins; the amine hydrogen equivalent is low; when mixed with low molecular weight epoxy resins to prepare water-based epoxy resins; The amount of curing agent is less; the introduction of hydrophilic polyether segments is less, the water resistance is improved; the construction is convenient.

(5) Preparation of water-based epoxy resin

Component A: E-51 10 grams

Butyl glycidyl ether 1.2g

Component B: modified curing agent 24.8 grams

Mix the two materials of component A evenly, slowly add them to component B under high-speed stirring, stir and disperse for 5 minutes to prepare the water-based epoxy resin coating.

The performance test results of epoxy resin coating are as follows:

Curing temperature: (25±1)℃

Curing speed: Surface dry 70min GB-1728-79(88)

Paint film hardness:                       

Paint film adhesion 95% of remaining squares GB 9286-88

Water resistance 30 hours no blistering, no peeling GB 1733-79(88)

Example 2

(1) Condensation reaction of epoxy resin and polyether diol.

In a four-neck flask with condensed water and nitrogen protection, epoxy resin E-51 was dropped in 216 grams and polyethylene glycol 1000 in an amount of 250 g. The temperature of the flask was raised to 70°C, and the reaction materials were fully mixed evenly under stirring. Then 12.2 g of zinc oxide was added as a catalyst. In the initial stage of the reaction, a large amount of reaction heat will be released. At this time, attention should be paid to opening the condensed water, and at the same time, the flow rate of the protective gas nitrogen should be increased to take away the heat and make it fully dissipate. The temperature was controlled at about 100°C, and the reaction was stirred for 6 hours. Samples were taken to determine the epoxy value.

In the condensate obtained above, add 216 grams of epoxy resin into the flask and stir evenly. Cool to room temperature.

(2) capping

Add 242 g of triethyleneamine to another four-necked flask. Then add 200 g of water, stir to dissipate heat, control the temperature at 68° C., slowly add 97 g (1.83 mol) of acrylonitrile dropwise through an addition funnel, and react for 1.5 hours.

(3) Addition modification to polyethylene polyamine

Add the product obtained in (1) dropwise to (2), the reaction temperature is 70°C and the reaction time is 2 hours. Note that the dropwise addition should be done slowly.

(4) into salt

Add 72 grams of acetic acid to form a salt, the reaction temperature is 75°C, and the reaction time is 100 minutes. After completion, add 530 grams of water and stir for 30 minutes to obtain a translucent light yellow viscous liquid.

After testing, the solid content is 45%, the viscosity is 8.4ps (25±1°C), and the amine hydrogen equivalent is 293.

This curing agent has no volatile organic compounds (VOC), which improves environmental performance; it has emulsifying and curing effects on low-molecular-weight epoxy resins; the amine hydrogen equivalent is low, and when mixed with low-molecular-weight epoxy resins to prepare water-based epoxy resins, curing The amount of agent is less, the introduction of hydrophilic polyether chains is less, the water resistance is improved, and the construction is convenient.

(5) Preparation of water-based epoxy resin

A component:

E-51 epoxy resin 10 grams

Butyl glycidyl ether 1.0 g

Component B: modified curing agent 17.5 grams

Mix the two materials of component A evenly, slowly add them to component B under high-speed stirring, stir and disperse for 5 minutes to prepare the water-based epoxy coating.

The performance test results of epoxy resin coating are as follows:

Curing temperature: (25±1)℃

Curing speed: Surface dry 85min GB-1728-79(88)

Paint Film Hardness 1H GB 6739-86

Adhesion of paint film                                              

Water Resistance No blistering or peeling for 30 hours GB 1733-79(88)

Example 3

(1) Condensation reaction of epoxy resin and polyether diol

In a four-neck flask with condensed water and nitrogen protection, add 20 grams of epoxy resin E-51 and 46.4 grams of polyethylene glycol PEG2000. The temperature of the flask was raised to 70°C, and the reaction materials were fully mixed evenly under stirring. Then 1.3 g of zinc chloride was added as a catalyst. In the initial stage of the reaction, a large amount of reaction heat will be released. At this time, attention should be paid to opening the condensed water, and at the same time, the flow rate of the protective gas nitrogen should be increased to take away the heat and make it fully dissipate. Control the temperature at about 90°C and stir for 8 hours. Samples were taken to determine the epoxy value.

(2) Addition modification of aliphatic polyamines

Add 24.0 grams of triethylenetetramine into the above four-necked flask (at this time, the flask should be cooled to about 50°C first), stir for about 15 minutes, control the temperature at about 65°C, and slowly add 20.0 grams of epoxy resin E- 51. In order to prevent the heat of reaction released during the addition from causing gelation, 25 ml of water was added before adding epoxy resin E-51. After adding E-51 dropwise. The stirring reaction was continued for 2.5 hours.

(3) capping

Add 15 grams of distilled water to the adduct obtained above to make the solid content about 75%. After adding water, stir for 30 minutes, and then slowly add 11 g of acrylonitrile dropwise for capping.

The reaction temperature is controlled at about 70°C. The reaction time was 2.0 hours.

(4) into salt

In the end-capped product, 8.0 g of organic acid acetic acid was added to carry out a salt-forming reaction to improve the water solubility of the solution. The reaction temperature was 80°C, and the reaction time was 1.5 hours. After the reaction was finished, 75 grams of water was added to adjust the solid content, and it became a translucent light yellow viscous liquid.

After testing, the solid content is 45.2%, the amine hydrogen equivalent is 440, and the viscosity is 11.95 pas (25±1°C).

This curing agent has no volatile organic compounds (VOC), which improves environmental performance; it has emulsifying and curing effects on low molecular weight epoxy resins; the amine hydrogen equivalent is low, and when mixed with low molecular weight epoxy resins to prepare water-based epoxy resins, The amount of curing agent is less, the water resistance is improved and the construction is convenient.

(5) Preparation of water-based epoxy resin

A component

E-51 15 grams

Butyl glycidyl ether 1.6g

B component

Modified curing agent 25.8 grams

Mix the two materials of component A evenly, slowly add them to component B under high-speed stirring, stir and disperse for 5 minutes to prepare the water-based epoxy coating.

The performance test results of epoxy resin coating are as follows:

Curing temperature: (25±1)℃

Curing speed: Surface dry 70min GB-1728-79(88)

Paint film hardness:                       

Paint film adhesion 95% of remaining squares GB 9286-88

Water resistance                                                                                                                                

This curing agent has no volatile organic compounds (VOC), which improves environmental performance; it has emulsifying and curing effects on low molecular weight epoxy resins; the amine hydrogen equivalent is low, and when mixed with low molecular weight epoxy resins to prepare water-based epoxy resins, The amount of curing agent is less, the introduction of hydrophilic polyether chains is less, the water resistance is improved, and the construction is convenient.

Claims (6)

1, a kind of preparation method of aqueous epoxy resin curing agent is characterized in that comprising the steps and processing condition:

(1) condensation reaction of Resins, epoxy and polyether Glycols: under zinc chloride catalysis, generate condensation product by Resins, epoxy and polyether Glycols, the mol ratio of Resins, epoxy and polyether Glycols is 2.2～2.0: 1.0, temperature of reaction is controlled at 90～100 ℃, and the reaction times is 6～8 hours;

(2) to the polyethylene polyamine addition modification: by the epoxide group mol ratio is 1.0: 2.0～2.2, step (1) condensation product is mixed with low-molecular-weight epoxy resin, again be dissolved in distilled water in polyethylene polyamine mix, in temperature is 2～3 hours 65～70 ℃ of following reaction times of condition, in the mixture of integral body, amine hydrogen amount and epoxy group(ing) mol ratio are 6.2～6.4: 1.0, and water-content is 20%～30%;

(3) end-blocking: the polyethylene polyamine modifier of vinyl cyanide and step (2) gained is pressed itrile group and primary amine hydrogen with 1.1～1.2: 1.0 mixed in molar ratio is to react 1.5～2.0 hours under 65～70 ℃ of conditions in temperature;

(4) salify: to the product behind end-blocking, adopting has monobasic organic acid salify; The equivalence ratio of organic acid and residue amine hydrogen is 1.0: 4.5～5.0,65～70 ℃ of temperature of reaction, and the reaction times has 1.0～1.5 hours, after reaction finishes, adds distilled water, gets aqueous epoxy resin curing agent.

2, the preparation method of a kind of aqueous epoxy resin curing agent according to claim 1 is characterized in that described polyether Glycols is a polyoxyethylene glycol, and molecular-weight average is 1000～2000.

3, the preparation method of a kind of aqueous epoxy resin curing agent according to claim 1 is characterized in that described catalyzer is a zinc chloride, and its add-on is 1.0～3.0% of a system weight.

4, the preparation method of a kind of aqueous epoxy resin curing agent according to claim 1 is characterized in that described low-molecular-weight epoxy resin is the bisphenol-A liquid resin, comprises E-51 type or E-44 Resins, epoxy.

5, the preparation method of a kind of aqueous epoxy resin curing agent according to claim 1, the polyethylene polyamine that it is characterized in that described step 2 is diethylenetriamine, triethylene tetramine or tetraethylene pentamine.

6, by the aqueous epoxy resin curing agent of the described method preparation of claim 1, it is characterized in that: solid content is 45～50%, and amine value scope is 290～500, and viscosity is 8.0ps～14ps.