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Preparation of low free monomer, degradable persimmon tannin modified phenolic resin

A phenolic resin, low free technology, applied in the field of preparation of modified phenolic resin to reduce pollution

Inactive Publication Date: 2008-12-24
WUHAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Nevertheless, the literature reports are all relatively low molecular weight tannins such as black wattle tannin, mangrove tannin, chestnut tannin, wattle bark tannin, maple tannin, larch tannin, etc. So far there is no report of tannin modified phenolic resin with larger molecular weight

Method used

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  • Preparation of low free monomer, degradable persimmon tannin modified phenolic resin
  • Preparation of low free monomer, degradable persimmon tannin modified phenolic resin

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Take 28.5g of phenol and 8g of persimmon tannin solution (mass concentration of tannin≥3wt%), add them into a reaction vessel equipped with a reflux condenser and an electric stirrer, stir evenly and add 0.85g of oxalic acid. The temperature was raised to 90° C., and 15.5 g of formaldehyde solution was added dropwise (the mass concentration of formaldehyde in the formaldehyde solution was 38%, at this time, the molar ratio of formaldehyde to phenol was 0.64). After 50 minutes, the formaldehyde solution was added dropwise. Then heat to 95°C to reflux the reactants for 60 minutes, depressurize (pressure 0.04Mpa) for dehydration, stop dehydration when the viscosity of the resin reaches 110cPa.s, cool down to 30°C and collect the materials to obtain low free monomer and degradable Persimmon tannin modified phenolic resin. The test results of the obtained resin are shown in Table 1.

Embodiment 2

[0023] Take 28.5g of phenol and 14g of persimmon tannin solution (mass concentration of tannin≥3wt%), add them into a reaction vessel equipped with a reflux condenser and an electric stirrer, stir evenly and add 0.85g of oxalic acid. The temperature was raised to 95° C., and 24.85 g of formaldehyde solution was added dropwise (the mass concentration of formaldehyde in the formaldehyde solution was 39%, and at this time, the molar ratio of formaldehyde to phenol was 1.06). After 60 minutes, the formaldehyde solution was added dropwise. Reheat to 95°C and react for 70 minutes, then dehydrate under reduced pressure (pressure is 0.03Mpa), stop dehydration when the viscosity of the resin reaches 200cPa.s, cool down to 30°C and collect materials, and obtain low free monomer, degradable persimmon tannin Modified phenolic resin. The test results of the obtained resin are shown in Table 1.

Embodiment 3

[0025] Get 28.2g of phenol, 14g of persimmon tannin solution (mass concentration of tannin ≥ 3wt%), add in the reaction vessel that reflux condenser, electric stirrer are housed, after stirring evenly, add the hydrochloric acid 0.5g that mass concentration is 20%. The temperature was raised to 95° C., and 20.62 g of formaldehyde solution was added dropwise (the mass concentration of formaldehyde in the formaldehyde solution was 39%, and at this time, the molar ratio of formaldehyde to phenol was 0.89). After 60 minutes, the formaldehyde solution was added dropwise. Reheat to 95°C and react for 70 minutes, dehydrate under reduced pressure (pressure is 0.05Mpa), stop dehydration when the viscosity of the resin reaches 300cPa.s, cool down to 30°C and collect the material, and obtain low free monomer, degradable persimmon tannin Modified phenolic resin. The test results of the obtained resin are shown in Table 1.

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Abstract

The invention relates to a method for preparing a modified phenol-formaldehyde resin. The method for preparing the degradable persimmon tannin modified phenol-formaldehyde resin with low free monomer content is characterized by comprising the following steps: firstly, raw materials are selected, namely phenol, a formaldehyde solution, a persimmon tannin solution and a catalyst are selected for standby according to the fact that the dosage of the persimmon tannin solution is 16.7 to 50 weight percent of the phenol, the mol ratio of formaldehyde to the phenol is between 0.6 and 1.5, and the dosage of the catalyst is 2 to 5 weight percent of the phenol; secondly, the phenol and the persimmon tannin solution are added into a reaction container in turn, uniformly stirred and then added with the catalyst, and the temperature is raised to between 80 and 100 DEG C; thirdly, the formaldehyde solution is dripped and the dripping process is finished within 30 and 60 minutes; and fourthly, after the dripping process is over, the mixture is heated to between 95 and 100 DEG C, undergoes reaction for 1 to 2 hours, and then undergoes decompression dehydration, and the degradable persimmon tannin modified phenol-formaldehyde resin with the low free monomer content is prepared through dehydration termination when the viscosity reaches between 100 and 600 cPa.s and temperature reduces to between 20 and 40 DEG C. The persimmon tannin modified phenol-formaldehyde resin has the characteristics of low free monomer content and degradability.

Description

technical field [0001] The invention relates to a preparation method of a modified phenolic resin, which belongs to the field of chemical raw materials and synthetic materials. Background technique [0002] Phenolic resin is one of the most widely used wood adhesives. In 2000, phenolic resin used in wood adhesives reached 82,000 tons, accounting for 20.2% of the total output of wood adhesives, which is second only to urea-formaldehyde resin. However, urea-formaldehyde resin is not waterproof, and the plywood processed by it is easy to be damp and crack, which seriously affects the service life of wood products. Phenolic resin has excellent waterproof performance and is widely used in high value-added products of exterior grade plywood, particleboard, fiberboard, and laminate. However, phenolic resin adhesives also have obvious shortcomings. Firstly, their raw material cost is high and expensive, and secondly, they are brittle and have low adhesive strength. [0003] Due to...

Claims

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Application Information

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IPC IPC(8): C08G8/24
Inventor 王勇邓雷邢凯华张联盟
Owner WUHAN UNIV OF TECH
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