阅读说明：本技术 一种腰果酚聚醚改性的aba型水性环氧树脂及其制备方法 (Cardanol polyether modified ABA type waterborne epoxy resin and preparation method thereof ) 是由 史正海 陈荣付 朱胜仙 张猛 李爽 张妍 于 2020-07-23 设计创作，主要内容包括：本发明提供了一种腰果酚聚醚改性的ABA型水性环氧树脂,其结构式如下式(I)所示。本发明提供的ABA型水性环氧树脂制备方法简单,原料易得,是以双酚A环氧树脂和腰果酚聚醚为原料,在无机载体负载有机锡的负载型催化剂作用下制得腰果酚改性的双酚A环氧树脂,之后用环氧化试剂将腰果酚上不饱和双键环氧化,最终制备得到ABA型水性环氧树脂,其和双酚A型环氧树脂,水一起可以制备得到高度稳定的水性环氧乳液,制成的清漆涂层耐盐,耐酸,耐碱,耐油,具有很好的耐腐蚀性能<Image he="136" wi="700" file="DDA0002599183470000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention provides an ABA type waterborne epoxy resin modified by cardanol polyether, which has a structural formula shown as a formula (I). The ABA type waterborne epoxy resin provided by the invention is simple in preparation method and easy in obtaining of raw materials, bisphenol A epoxy resin and cardanol polyether are used as raw materials, the cardanol modified bisphenol A epoxy resin is prepared under the action of a supported catalyst of organic tin supported by an inorganic carrier, then an epoxidation reagent is used for epoxidizing unsaturated double bonds on cardanol, and finally the preparation method is usedThe obtained ABA type waterborne epoxy resin, the bisphenol A type waterborne epoxy resin and water can be used for preparing highly stable waterborne epoxy emulsion together, and the prepared varnish coating has the advantages of salt resistance, acid resistance, alkali resistance, oil resistance and good corrosion resistance)

1. An ABA type waterborne epoxy resin modified by cardanol polyether has a structural formula shown as the following formula (I):

wherein, R is straight-chain alkane with 15-17C atoms and straight-chain alkane at least containing one epoxide group, and the total molar content of the straight-chain alkane containing the epoxide group exceeds 80 percent; q isOrWherein denotes the attachment site on the Q group;

m is an integer of 15 to 70, and n is an integer of 0 to 5.

2. The aqueous epoxy resin of claim 1, wherein m is an integer from 22 to 45 and n is an integer from 1 to 3.

3. The waterborne epoxy resin of claim 1, wherein R is at least one of the following structures (i) to (iv):

(i)

(ii)

(iii)

(iv)

provided that the sum of the molar contents of the linear alkanes containing epoxide groups is more than 80%, preferably more than 90%, more preferably more than 95%.

4. The preparation method of the cardanol polyether modified ABA type waterborne epoxy resin as claimed in any one of claims 1-3, comprising the following steps:

(1) preparation of cardanol polyoxyethylene ether epoxy resin: in the presence of a catalyst, reacting cardanol polyoxyethylene ether with bisphenol A epoxy resin in a heating and melting state to obtain cardanol polyoxyethylene ether epoxy resin;

(2) performing epoxidation, namely dissolving cardanol polyoxyethylene ether epoxy resin in an organic solvent, adding organic carboxylic acid, uniformly stirring, and then dropwise adding an epoxidizing agent to obtain the cardanol polyether modified ABA type waterborne epoxy resin;

the catalyst is a supported catalyst of inorganic carrier supported organotin.

5. The method according to claim 4, wherein the molar ratio of the cardanol polyoxyethylene ether to the bisphenol A type epoxy resin in step (1) is 1: 1 to 2.5, preferably, the bisphenol A epoxy resin has an epoxy equivalent weight of 170-900g/mol, preferably epoxy resins E51, E44 and E20.

6. The preparation method according to claim 4, wherein in step (1), the molecular weight of the polyoxyethylene ether segment in the cardanol polyoxyethylene ether is 600-4000, preferably 1300-2200; and/or in the step (2), the epoxidizing agent is 30-50% of hydrogen peroxide, and the hydrogen peroxide is dropwise added into the reaction system, wherein the amount of the hydrogen peroxide is 15-30% of the mass of the cardanol polyoxyethylene ether.

7. The method of claim 4, wherein the catalyst is a halloysite nanotube-supported organotin catalyst, and the halloysite nanotube is 300-400 mesh; the organic tin is at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin acetate and dibutyltin maleate; the addition amount of the catalyst is 1-5% of the mass of the cardanol polyoxyethylene ether, and preferably 2-3%.

8. The method of claim 7, wherein the supported catalyst of the halloysite nanotube supported organotin is obtained by a method of preparation comprising the steps of:

adding the halloysite nanotube and organic tin into an organic solvent, adding a dispersion stabilizer, uniformly dispersing under a stirring condition, washing, and drying to obtain the supported catalyst.

9. The method of claim 8, wherein the halloysite nanotubes and the organotin are present in a mass ratio of 1: 1-3; the dispersion stabilizer is at least one of sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate, and the dosage of the dispersion stabilizer is 1-2% of the total mass of the halloysite nanotube and the organic tin.

10. An aqueous epoxy emulsion prepared from a bisphenol A type epoxy resin as a main component and an ABA type epoxy resin obtained by using the ABA type epoxy cardanol polyoxyethylene ether as an emulsifier and water, wherein the emulsifier is the ABA type aqueous epoxy resin according to any one of claims 1 to 3 or the ABA type aqueous epoxy resin obtained by the preparation method according to any one of claims 4 to 9.

Technical Field

The invention belongs to the field of chemical industry, and particularly relates to a water-based epoxy resin and a preparation method thereof.

Background

The epoxy resin has excellent adhesive force and mechanical property, excellent water resistance and chemical corrosion resistance, and is widely applied to various fields such as coating, composite materials, adhesives and the like. However, epoxy resins are hardly soluble in water, and are generally dissolved in organic solvents such as aromatic hydrocarbons, ketones, or alcohol ethers to prepare resin solutions with a certain concentration and viscosity for use. The use of the organic solvent is high in cost, and the organic solvent is flammable and explosive, so that great potential safety hazards exist, and in addition, the volatilization of a large amount of organic solvent in the use process causes personal injury and air pollution to different degrees. Therefore, the water-based epoxy resin is becoming the mainstream direction for the application of epoxy resins.

The methods for making epoxy resins into water are roughly classified into three types: mechanical methods, chemical modification methods and phase inversion methods. The mechanical method is that solid epoxy resin is ground into micron-sized epoxy resin powder in advance, then an emulsifier is added and mixed uniformly, and resin particles are dispersed in water by force through mechanical stirring, so that the emulsion belongs to a heterogeneous system with unstable free energy, the prepared emulsion has poor stability and is easy to coagulate, and the emulsion breaking phenomenon can occur when the emulsion is placed for a long time or centrifuged. The chemical modification method is also called self-emulsification method, namely some hydrophilic chain segments are introduced to the molecular chain of the epoxy resin through chemical reaction, so that the epoxy resin has both hydrophilic groups and hydrophobic groups, and the epoxy resin is used as an emulsifier. However, the general modification method has complex synthetic steps and high cost. At present, the phase inversion method is mostly used, in which an emulsifier and an epoxy resin are uniformly mixed, then water is added into a system under the condition of high shear force, the system is changed from water-in-oil to oil-in-water through phase inversion, and a heterogeneous system with small free energy is formed, so that the system is a stable dilutable system. The aqueous epoxy resin emulsion prepared by the phase inversion method has the advantages of simple operation, low cost, small added emulsifier amount and the like, the particle size of the prepared emulsion can reach the nanometer level, and the emulsion has high stability, thereby being the mainstream production method of the aqueous epoxy resin emulsion in the market at present. The key of the method lies in the selection of the high-efficiency emulsifier.

In aqueous epoxy emulsions, nonionic emulsifiers are mainly used at present. The types of nonionic emulsifiers on the market are many, and the nonionic emulsifiers are mainly amphiphilic polymers prepared by reacting bisphenol A epoxy resin with polyethylene glycol, alkylphenol polyether and the like. The epoxy resin is an AB type high molecular polymer with one end being an epoxy group and the other end being a hydroxyl group, wherein A is an epoxy resin chain segment and B is a polyether chain segment. Because the epoxy end group is oleophilic and the hydroxyl end group is hydrophilic, the balance of the emulsion prepared by the epoxy resin emulsion is easy to damage, and the emulsion has poor stability. More importantly, because the terminal hydroxyl does not participate in the curing reaction and exists in a free state, the integrity of the whole cross-linked network is damaged due to the free form of the tail end of the emulsifier in the film forming process of the emulsion, and finally the water resistance and the corrosion resistance of the coating film of the coating are poor.

Patent CN105315437A discloses a nonionic self-emulsifying waterborne epoxy curing agent, which is used for preparing waterborne epoxy emulsion with good stability, and after the coating is formed into a film, the coating is acid-resistant, alkali-resistant and oil-resistant. But on the one hand, the preparation process is complex, and on the other hand, the stability of the AB type epoxy resin emulsifier can not meet the requirements. Patent CN110330862A discloses a water-based epoxy anticorrosive paint, which does not disclose the stability of water-based epoxy emulsion, which is the most critical factor for restricting water-based epoxy emulsion, and the patent uses graphene with high cost, which is not beneficial for the preparation of large-scale water-based epoxy emulsion for industrialization.

The ABA type emulsifier with epoxy groups at two ends and polyoxyethylene ether chain segment in the middle is prepared, and the waterborne epoxy resin prepared by the emulsifier can effectively improve the corrosion resistance of the final coating. Patent CN109734922A reports a nonionic reactive epoxy resin emulsifier, which uses cardol polyether as raw material, and bisphenol a epoxy resin in a ratio of 1: reacting at a molar ratio of 2 to obtain the ABA type waterborne epoxy resin. Compared with the traditional AB type emulsifier, the ABA type emulsifier has more excellent performance, but the production difficulty of the patent is high, the activity of hydroxyl on a polyether segment is weak, the finally obtained product is often complex in components, besides the ABA type polymer, a diblock or multiblock polymer also exists in the product, the uniform ABA type emulsifier is difficult to obtain, and the stability of the obtained epoxy emulsion needs to be further improved.

Disclosure of Invention

In order to overcome the defects of poor stability and the like of the emulsifier of the waterborne epoxy resin in the prior art, the invention aims to provide an ABA type waterborne epoxy resin based on cardanol and a preparation method thereof.

The invention aims to provide an ABA type waterborne epoxy resin modified by cardanol polyether, which has a structural formula shown as the following formula (I):

wherein, R is straight-chain alkane with 15-17C atoms and straight-chain alkane at least containing one epoxide group, and the total molar content of the straight-chain alkane containing the epoxide group exceeds 80 percent; q is

OrWherein denotes the attachment site on the Q group.

m is an integer of 15 to 70, preferably 22 to 45; n is an integer of 0 to 5, preferably 1 to 3.

Further, the R is at least one of the following structures (i) to (iv):

provided that the sum of the molar contents of the linear alkanes containing epoxide groups is more than 80%, preferably more than 90%, more preferably more than 95%.

The second purpose of the invention is to provide a preparation method of the cardanol polyether modified ABA type waterborne epoxy resin, which comprises the following steps:

(1) preparation of cardanol polyoxyethylene ether epoxy resin: in the presence of a catalyst, reacting cardanol polyoxyethylene ether with bisphenol A epoxy resin in a heating and melting state to obtain cardanol polyoxyethylene ether epoxy resin;

(2) and (3) epoxidation, namely dissolving the cardanol polyoxyethylene ether epoxy resin in an organic solvent, adding organic carboxylic acid, uniformly stirring, and then dropwise adding an epoxidizing agent to obtain the cardanol polyether modified ABA type waterborne epoxy resin.

Further, the mol ratio of the cardanol polyoxyethylene ether to the bisphenol A epoxy resin in the step (1) is 1: 1-2.5.

Preferably, the bisphenol A epoxy resin has an epoxy equivalent of 170-900g/mol, and preferably epoxy resins E51, E44 and E20.

In the step (1), the molecular weight of the polyoxyethylene ether segment in the cardanol polyoxyethylene ether is 600-4000, preferably 1300-2200.

Preferably, the catalyst in the step (1) is a halloysite nanotube-supported organotin catalyst, and the halloysite nanotube is 300-400 meshes; the organic tin is at least one of dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin acetate and dibutyltin maleate; the addition amount of the catalyst is 1-5% of the mass of the cardanol polyoxyethylene ether, and preferably 2-3%.

The supported catalyst of the halloysite nanotube supported organotin is obtained by the preparation method comprising the following steps:

adding the halloysite nanotube and organic tin into an organic solvent, adding a dispersion stabilizer, uniformly dispersing under a stirring condition, washing, and drying to obtain the supported catalyst.

The mass ratio of the halloysite nanotubes to the organic tin is 1: 1-3; the organic solvent is not particularly limited, and a good organic tin solvent may be selected, and examples thereof include, but are not limited to, acetone, diethyl ether, ethyl acetate, dichloromethane, and chloroform. Acetone or diethyl ether is preferred because of its lower boiling point, which facilitates subsequent removal.

The dispersion stabilizer is at least one selected from sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, ammonium hydrogen phosphate and ammonium dihydrogen phosphate. The amount of the dispersion stabilizer is generally 1-2% of the total mass of the halloysite nanotubes and the organotin.

In the step (1), the heating and melting are carried out at the temperature of 70-100 ℃, after the stirring and the mixing are uniform, the temperature of the reaction kettle is controlled at 80-120 ℃, the closed reaction is carried out for 4-8 hours until the epoxy equivalent index reaches the theoretical fixed value, and the cardanol polyoxyethylene ether epoxy resin is obtained.

In the step (2), the organic solvent is at least one of dichloromethane, chloroform, toluene, xylene, ethyl acetate and ethyl bromide, and the organic acid is at least one of formic acid, acetic acid, propionic acid and oxalic acid. Preferably, the mass ratio of the cardanol polyoxyethylene ether epoxy resin, the organic solvent and the organic carboxylic acid is 1-1.5. The adding amount of the organic acid is 5-10% of the mass of the cardanol polyoxyethylene ether.

In the step (2), the epoxidizing agent is hydrogen peroxide, and is generally added into the reaction system dropwise by adopting 30-50% hydrogen peroxide. The dosage of the hydrogen peroxide is 15-30% of the mass of the cardanol polyoxyethylene ether.

In the step (2), the reaction temperature is controlled to be 40-60 ℃, and the reaction is carried out for 4-8 hours.

And (2) oxidizing carbon-carbon unsaturated double bonds on side chains of the cardanol polyoxyethylene ether epoxy resin obtained in the step (1) into epoxy functional groups, and finally obtaining an ABA type epoxy cardanol polyoxyethylene ether epoxy resin product capable of being used for water-based epoxy resin.

Because the reactivity of the hydroxyl on the polyether segment on cardanol is not strong, and when the hydroxyl on the polyether segment on cardanol reacts with the epoxy group on bisphenol A, a catalyst with strong activity, such as SnCl, is needed₄，TiCl₄. However, the inorganic catalyst is strongly hydrolyzed, and is inconvenient to store and use; and can be deactivated relatively quickly in the reaction process, which is not suitable for synthesizing stable water-based epoxy emulsion. The inventor unexpectedly finds that the supported catalyst obtained by adopting halloysite nanotubes to support organic tin can effectively catalyze the reaction, and the cardanol polyether modified epoxy resin with narrow molecular distribution and uniform product is obtained.

The invention provides a water-based epoxy emulsion which is prepared by using bisphenol A type epoxy resin as a main component, using ABA type epoxy cardanol polyoxyethylene ether epoxy resin as an emulsifier and water.

Further, the aqueous epoxy emulsion is obtained by a preparation method comprising the following steps: adding bisphenol A type epoxy resin and the ABA type epoxy cardanol polyoxyethylene ether epoxy resin into a container, heating to be molten, and fully and uniformly mixing the epoxy resin and an emulsifier under the stirring condition; heating, increasing the stirring speed, slowly dripping water, continuing stirring after dripping is finished, cooling to room temperature, and filtering to obtain the water-based epoxy emulsion.

The mass ratio of the bisphenol A type epoxy resin to the ABA type epoxy cardanol polyoxyethylene ether epoxy resin is 10-15:1, and the mass ratio of the sum of the water and the epoxy resin, namely the sum of the bisphenol A type epoxy resin and the ABA type epoxy cardanol polyoxyethylene ether epoxy resin is 1-1.5: 1.

The heating to melting is carried out to 60-70 ℃, the stirring speed under the stirring condition is 500-700r/min, and the stirring time is 0.5-1 h; the temperature rise refers to the temperature rise to 80-90 ℃, and the stirring speed increase refers to the stirring speed of 1500-2000 r/min.

The invention has the following beneficial effects:

firstly, cardanol is extracted from cashew shells, and the cashew shells are rich in source, low in price, safe and environment-friendly;

secondly, the invention provides a synthetic route for preparing the high-stability ABA type waterborne epoxy resin, and compared with the prior art, the process control is simple, and the product purity is high.

Thirdly, the halloysite-loaded organic tin is adopted as a catalyst, the cardanol polyoxyethylene ether epoxy resin can be uniformly and stably prepared and then epoxidized, the molecular weight distribution of the obtained product is narrow, the stability of the water-based epoxy emulsion prepared by using the halloysite-loaded organic tin as an emulsifier is good, the water-based epoxy emulsion can be stable under high-temperature and centrifugal conditions, and the application is convenient.

Drawings

Fig. 1 is a GPC spectrum of the cardanol polyether modified ABA type waterborne epoxy resin obtained in example 2 and comparative example 1.

FIG. 2 shows preparation of cardanol polyether modified ABA type waterborne epoxy resin obtained in example 2¹HNMR spectrogram.

Detailed Description

The following description further explains the cardanol polyether modified ABA type waterborne epoxy resin and the preparation method thereof with the drawings and examples in the specification, but it should be understood that the contents of the specific examples are only for explaining the contents of the present invention and should not be construed as limiting the contents of the present invention.

Preparation examplePreparation of Supported catalysts

Preparation example 1

Adding 10g of 300-mesh halloysite and 20g of dibutyltin dilaurate into 120g of acetone, adding 0.3g of sodium hydrogen phosphate under the stirring condition, continuing for 30min under the stirring condition of 2000rpm/min, filtering, vacuum drying, washing for 3 times by deionized water, and then vacuum drying again to obtain the supported catalyst loaded with dibutyltin dilaurate. The organotin loading was 22.47 wt% as determined by thermal gravimetric analysis.

Preparation example 2

Adding 10g of 300-mesh halloysite and 30g of dioctyltin dilaurate into 130g of diethyl ether, adding 0.5g of ammonium hydrogen phosphate under the stirring condition, continuing for 30min under the stirring condition of 2000rpm/min, filtering, vacuum drying, removing deionized water, washing for 3 times, and then vacuum drying again to obtain the supported catalyst loaded with the dioctyltin dilaurate. The organotin loading was 19.63 wt% as determined by thermogravimetric analysis.