阅读说明：本技术 一种选择性断开密胺树脂中c-o键的方法 (Method for selectively breaking C-O bond in melamine resin ) 是由 侯相林 武少弟 邓天昇 于 2020-07-15 设计创作，主要内容包括：本发明公开了一种选择性断开密胺树脂中C-O键的方法,涉及树脂固体废弃物循环利用及资源化领域。该方法为：将密胺树脂材料粉碎为块料,将其浸入酸性催化剂-溶剂的液相反应体系中加热反应,反应过程中酸性催化剂可有效作用于C-O键,使得材料本体中特定的CH<Sub>2</Sub>-O-CH<Sub>2</Sub>键断裂,待反应结束后降至室温,过滤洗涤得到产物三聚氰胺预聚体。本发明通过对废旧密胺餐具进行化学催化降解的方法,解决了化学处理方法中高温热解产物成分复杂,易于生成剧毒氢氰酸等难题,直接采用催化剂-溶剂体系反应,得到高附加值的三聚氰胺预聚体。(The invention discloses a method for selectively breaking C-O bonds in melamine resin, and relates to the field of recycling of resin solid waste. The method comprises the following steps: the melamine resin material is crushed into lump material and is soaked into a liquid phase reaction system of an acid catalyst-solvent for heating reaction, and the acid catalyst can effectively act on C-O bonds in the reaction process, so that specific CH in the material body 2 ‑O‑CH 2 Breaking bond, cooling to room temperature after reaction, filtering and washingTo obtain the product melamine prepolymer. The invention solves the problems of complex components of high-temperature pyrolysis products, easy generation of virulent hydrocyanic acid and the like in a chemical treatment method by carrying out chemical catalytic degradation on waste melamine tableware, and obtains the melamine prepolymer with high added value by directly adopting a catalyst-solvent system for reaction.)

1. A method for selectively breaking C-O bonds in melamine resins, comprising: the method comprises the steps of crushing melamine resin materials into lump materials, immersing the lump materials into a liquid phase reaction system of an acid catalyst-solvent, heating for reaction, cooling to room temperature after the reaction is finished, filtering and washing to obtain the melamine prepolymer.

2. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: the melamine resin material is crushed into lump materials, wherein the grain diameter of the lump materials is 10 mm-30 mm.

3. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: the acid catalyst is HCl and HNO₃、H₃BO₃、H₂SO₄、H₂CO₃、H₃PO₄、FeCl₃、AlCl₃、ZnCl₂、CuCl₂、MnCl₂One or more of p-toluenesulfonic acid and dodecylbenzene sulfonic acid are mixed according to any ratio.

4. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: the solvent is water or a mixed solution of water and an organic reagent.

5. The method according to claim 4, wherein the C-O bond in the melamine resin is selectively broken by: in the mixed solution of water and the organic reagent, the volume ratio of the water to the organic reagent is 1: 0.5-10.

6. The method according to claim 4, wherein the C-O bond in the melamine resin is selectively broken by: the organic reagent is one or more of methanol, ethanol, n-propanol, isopropanol, formic acid, acetic acid, tetrahydrofuran, diethyl ether, DMSO, dioxane, DMF, gamma-butyrolactone, gamma-valerolactone, acetone or ethylenediamine which are mixed according to any ratio.

7. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: crushing a melamine resin material into lump materials, immersing the lump materials into a liquid phase reaction system of an acid catalyst-solvent, and heating for reaction, wherein the mass ratio of the acid catalyst to the melamine resin is 1: 0.05-5; the mass ratio of the solvent to the melamine resin is 1-100: 1.

8. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: the temperature of the heating reaction is 50-200 ℃.

9. The method of claim 1, wherein the C-O bond in the melamine resin is selectively broken by: the reaction time of the heating reaction is 10 min-6 h.

Technical Field

The invention belongs to the field of cyclic utilization and resource utilization of resin solid wastes, and particularly relates to a method for selectively breaking C-O bonds in melamine resin.

Background

Melamine resin is also called melamine-formaldehyde resin, melamine-formaldehyde resin (MF), which is a polymer obtained by reacting melamine with formaldehyde. The product is used as a starting point, different process conditions are adopted according to different purposes, a series of products with different purposes are derived, a cross-linking reaction occurs during processing and molding, and the product is infusible thermosetting resin. Melamine resin is widely applied to a plurality of fields such as catering and children toys, and the like, and the yield of the melamine resin is about millions of tons every year in China. Because melamine resin products have high chemical stability and are not easily catalyzed and degraded by light, microorganisms, water and the like in the environment, a large amount of waste can be accumulated in living space of people, and not only occupies space, but also causes hidden troubles of soil pollution or underground water pollution.

The existing method for recovering and treating waste melamine resin mainly comprises a mechanical treatment method and a high-temperature pyrolysis method. The mechanical treatment method is to mechanically crush cured and molded melamine resin, to be used as a filler to be added into a new round of synthesis of thermosetting resin, and to regulate and control the size and filling amount of the mechanical crushing of the melamine resin according to the performance requirement of the synthetic resin. The method usually needs higher energy consumption, and the crushed melamine block material has small binding force with new resin, so that the mechanical property of a new melamine product is obviously influenced, the additional value is low, and the economical efficiency is poor. The high-temperature pyrolysis method is mainly used for carrying out high-temperature treatment on waste melamine resin, and chemical bonds in the resin are opened in a non-selective manner by utilizing high temperature, so that corresponding components are recovered.

Melamine (Melamine, chemical formula: C3N3(NH2)3), commonly known as Melamine and protamine, is named as 1, 3, 5-triazine-2, 4, 6-triamine by the International Union of Pure and Applied Chemistry (IUPAC)), is a triazine nitrogen-containing heterocyclic organic compound and is widely Applied to chemical raw materials. The melamine takes urea as raw material, and about 3 tons of urea are needed for producing 1 ton of melamine.

If the ether bond (i.e., CH) in the melamine resin can be reacted under appropriate reaction conditions₂-O-CH₂Bond) is selectively opened, melamine is catalytically degraded into melamine prepolymer, and the melamine prepolymer is conveniently re-pressurized, molded and recycled, so that the melamine prepolymer has higher economic value and social significance undoubtedly.

Disclosure of Invention

Aiming at the problems of low added value of products of the existing mechanical treatment method, difficult recovery of high-temperature pyrolysis products and the like, the invention provides a method for selectively breaking C-O bonds in melamine resin.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for selectively breaking C-O bond in melamine resin comprises pulverizing melamine resin material into lump material, soaking in acidic catalyst-solvent liquid phase reaction system, heating for reaction, wherein the acidic catalyst can effectively act on C-O bond during reaction process to make specific CH in material body₂-O-CH₂And (3) breaking bonds, cooling to room temperature after the reaction is finished, and filtering and washing to obtain the specific product melamine prepolymer. The invention realizes the catalytic degradation of melamine resin, the material is crushed, the mass transfer effect in the reaction process is convenient to improve, and the proper catalyst-solvent system is selected, so that the catalyst and the solvent can enter the material body and can be conveniently contacted with the active sites of the material reaction, and the catalytic degradation efficiency is further improved. Compared with the traditional treatment means, the method realizes the catalytic degradation of the melamine resin under mild conditions, and has simple product distribution and higher recovery rate.

Furthermore, the melamine resin material is crushed into blocks, wherein the particle size of the blocks is 10-30 mm. The particle size of the lump material is too large, which not only affects mass transfer, but also increases the porosity of a reaction system and affects degradation efficiency, and if the particle size is too small, the energy consumption is too high during crushing, more dust is generated in the production process, and the economical efficiency is not good.

Still further, the acidic catalyst is HCl and HNO₃、H₃BO₃、H₂SO₄、H₂CO₃、H₃PO₄、FeCl₃、AlCl₃、ZnCl₂、CuCl₂、MnCl₂One or more of p-toluenesulfonic acid and dodecylbenzene sulfonic acid are mixed according to any ratio. The catalyst selected by the technical scheme has a good catalytic effect on the catalytic degradation of melamine resin.

Furthermore, the solvent in the step is water or a mixed solution of water and an organic reagent, and the organic reagent is specifically one or more of methanol, ethanol, n-propanol, isopropanol, formic acid, acetic acid, tetrahydrofuran, diethyl ether, DMSO, dioxane, DMF, gamma-butyrolactone, gamma-valerolactone, acetone or ethylenediamine which are mixed according to any ratio. The reaction solvent with strong reaction activity promotes the reaction of melamine resin through the action of the catalyst.

Further, the mixed solution of water and an organic reagent has a volume ratio of water to organic reagent of 1:0.5 to 10. By selecting a proper proportion, the mixed solvent has stronger reaction activity.

Furthermore, the melamine resin material is crushed into lump materials, and the lump materials are immersed into a liquid phase reaction system of an acid catalyst-solvent for heating reaction, wherein the mass ratio of the acid catalyst to the melamine resin is 1: 0.05-5; the mass ratio of the solvent to the melamine resin is 1-100: 1. The catalyst proportion range selected in the technical scheme has a good effect on the catalytic degradation of melamine resin, and the dissolution of the selected organic solvent and the recovered product melamine prepolymer is low, so that the subsequent separation is facilitated.

Furthermore, the heating reaction temperature in the step is 50-200 ℃, and the reaction time is 10 min-6 h. When the degradation temperature is lower than 50 ℃, the reaction rate of the reaction system is extremely low, and when the degradation temperature is higher than 200 ℃, the yield of the melamine prepolymer is not obviously improved. When the reaction time is less than 10min, the above reaction systems cannot completely catalyze the degradation of the melamine resin, and when the reaction time is more than 6h, the extension of the reaction time does not significantly promote the reaction of the melamine resin.

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

the invention solves the problems of complex components of high-temperature pyrolysis products, easy generation of virulent hydrocyanic acid and the like in a chemical treatment method by carrying out chemical catalytic degradation on waste melamine tableware, and obtains the melamine prepolymer with high added value by directly adopting a catalyst-solvent system for reaction.

The selected acid catalyst can enter the material body more quickly in a liquid phase reaction system, and is convenient to contact with the material reaction active site, so that the catalysis rate is improved.

Drawings

FIG. 1 is a reaction scheme of the present invention;

FIG. 2 shows the preparation of a melamine prepolymer as the product of example 1¹³A C-NMR spectrum;

FIG. 3 is an NMR hydrogen spectrum of a melamine prepolymer which is a product of example 1 of the present invention.

Detailed Description

The reaction scheme of a method for selectively breaking C-O bonds in melamine resin according to the present invention is shown in FIG. 1.