AU2019101692A4

AU2019101692A4 - Method for Modification of Fast Growing Wood Using Rosin-based Unsaturated Resin

Info

Publication number: AU2019101692A4
Application number: AU2019101692A
Authority: AU
Inventors: Xiaoping Rao; Shibin SHANG; Zhanqian Song; Ji Xu
Original assignee: Institute of Chemical Industry of Forest Products of CAF
Current assignee: Institute of Chemical Industry of Forest Products of CAF
Priority date: 2019-12-24
Filing date: 2019-12-24
Publication date: 2020-02-06
Anticipated expiration: 2027-12-24

Abstract

Abstract The invention discloses a method for modification of fast growing wood using a rosin based unsaturated resin, which comprises the steps of impregnating the fast growing wood in a solution of the rosin-based unsaturated resin in ethanol for 22-28 hours, and then removing and drying the fast growing wood, followed by curing, thereby obtaining the fast growing wood modified by the rosin-based unsaturated resin, wherein the solution of the rosin-based unsaturated resin in ethanol has a mass concentration of 3-25%. With the method for the modification of the fast growing wood using the rosin-based unsaturated resin according to the present invention, the fast growing wood has a density increased by 4.76 17.07%, a weight percent gain (WPG) of 4.90-18.16%, a hardness increased by 0.59-1.23%, and a contact angle increased from 64.57-12.73° to 111.81-73.25°, thereby reducing the limitation of the wood in application. The method is simple, easy to operate, low in cost, and explores new ways for the high-value use of rosin, which greatly increases its added value.

Description

Method for Modification of Fast Growing Wood Using Rosin-based Unsaturated Resin

Technical Field

The present invention relates to a method for modification of fast growing wood using a rosin-based unsaturated resin, and belongs to the field of fast growing wood modification.

Background

As a natural biomass material, wood has been widely used in the fields, such as furniture, construction, and decoration, due to its renewable and environmentally friendly properties. It is an important raw material in China's national economic construction. With the continuous improvement of people's quality of life, the demands for wood and its products have greatly increased, resulting in huge consumption of wood. Because of their advantage of abundant resources, planted fast growing forests will become the prevailing wood species to alleviate the contradiction between supply and demand in domestic and foreign markets in the future.

Due to the interaction between wood and water, dimensional instability and low resistance to biodegradation, wood, especially fast growing wood, is limited in its application. Among them, fast growing poplar has a short growth cycle and strong adaptability, which makes it very popular in the pulp, paper and veneer industries, and becomes an important tree species of first choice with fast-growing and high-yield characteristics in China. However, fast growing poplar has poor physical-mechanical properties, poor dimensional stability, and low corrosion resistance, so it is urgent to improve its performance. At present, fast growing poplar is modified mainly by two methods: impregnation treatment and non-impregnation treatment. In the impregnation treatment, urea-formaldehyde resin, acrylic ester emulsion, silica sol and the like are usually used for the impregnation modification of the poplar to enhance the thermal stability and mechanical properties of the wood. This method has been studied earlier in China, but it has environmental pollution problems such as the release of formaldehyde. The non-impregnation treatment includes, for example, compaction treatment and high-temperature heat treatment, in which the destruction of wood structure and the thermal degradation reaction of cellulose, hemicellulose and lignin may result in reduced mechanical strength of the wood. Therefore, it is of great practical significance to provide an environmentally friendly method for modification in the low and medium temperature range. Rosin is an abundant natural renewable resource in China. The main component of rosin is resin acid, which has high crystallinity, high molecular weight, high melting point and a tricyclic diterpene structure that provides it with favorable hydrophobicity, such that the rosin and its derivatives can be used to improve wood properties.

Summary

The present invention provides a method for modification of fast growing wood using a rosin-based unsaturated resin to significantly improve the performance of the fast growing wood.

The present invention solves the above technical problems by the following technical solutions.

The invention discloses a method for modification of fast growing wood using a rosinbased unsaturated resin, which comprises the steps of impregnating the fast growing wood in a solution of the rosin-based unsaturated resin in ethanol for 22-28 hours, and then removing and drying the fast growing wood, followed by curing, thereby obtaining the fast growing wood modified by the rosin-based unsaturated resin, wherein the solution of the rosin-based unsaturated resin in ethanol has a mass concentration of 3-25%.

The rosin-based unsaturated resin is prepared by an esterification reaction of hydrogenated rosin and glycidyl methacrylate. The rosin-based unsaturated resin has the following structural

O formula: O

The solution of the rosin-based unsaturated resin in ethanol contains AIBN as an initiator with a mass content of 2-4%.

In order to improve the modification effect, the impregnating is carried out at a vacuum of 0.08 to 0.1 MPa for 25 to 50 minutes, and then at atmospheric pressure for 22 to 27 hours.

In order to further improve the modification effect, the drying is carried out at a temperature of 45-55°C for 4-6 hours to remove the ethanol. The curing is carried out at a temperature of 90-100°C for 2-5 hours, followed by raising the temperature to 130-160°C for post-curing for 1-8 hours, to obtain the fast growing wood modified by the rosin-based unsaturated resin. The applicant investigated the thermal curing process of the rosin-based unsaturated resin by DSC method to determine the temperature range used for the thermal curing to perform the stepwise curing, which can provide a more significant improvement of the modification effect.

The fast growing wood modified by the rosin-based unsaturated resin has a density increased by 4.76-17.07%, a weight percent gain (WPG) of 4.90-18.16%, a hardness increased by 0.59-1.23%, and a contact angle increased by 47.41-75.68°, compared with before modification.

For the technologies not mentioned in the present invention, reference is made to the prior art.

With the method for the modification of the fast growing wood using the rosin-based unsaturated resin according to the present invention, the fast growing wood has a density increased by 4.76-17.07%, a weight percent gain (WPG) of 4.90-18.16%, a hardness increased by 0.59-1.23%, and a contact angle increased from 64.57-12.73° to 111.81-73.25°, thereby reducing the limitation of the wood in application. The method is simple, easy to operate, low in cost, and explores new ways for the high-value use of rosin, which greatly increases its added value.

Brief Description of the Drawings

FIG. 1 is an image showing contact angles of a control wood sample and a wood sample which was subjected to impregnation treatment with a solution of 20 wt% rosin-based unsaturated resin in ethanol.

FIG. 2 is a graph showing dynamic wettability.

Detailed Description of the Embodiments

In order to better understand the present invention, the content of the present invention is further clarified below with reference to the examples, but the content of the present invention is not limited to the following examples.

Example 1

A rosin-based unsaturated resin having the following structural formula was prepared by performing an esterification reaction with hydrogenated rosin and glycidyl methacrylate (GMA) as starting materials.

O O

Example 2

Unbroken poplar blocks with a size of 20 x 20 x 20 mm³ were randomly selected, dried at 105°C until constant weight, and the weight and size of the blocks were measured. Solutions of the above rosin-based unsaturated resin in ethanol were formulated at a mass concentration of 5%, 10%, 15% and 20%, respectively, and an initiator AIBN was added at a weight ratio of 2%. Meanwhile, an equal amount of absolute ethanol solution was used as a control group. The fast growing wood was impregnated in the solutions of the rosin-based unsaturated resin in ethanol or the absolute ethanol solution at a vacuum of 0.095 MPa for 30 minutes, and then at room temperature (20-27°C) and atmospheric pressure for 24 hours. After that, the fast growing wood was filtered out and dried in an oven at 45°C for 4 hours, and heated to 95°C for curing for 4

2019101692 24 Dec 2019 hours, and then heated to 130°C for post-curing for 8 hours, thereby giving the fast growing wood which was cured and modified. The weight and size of the wood samples were measured, the densities before and after impregnation were calculated, and the weight percent gains were calculated. For the fast growing wood impregnated with the solution of the rosin-based 5 unsaturated resin in ethanol, after curing, the fast growing wood had a density increased by 4.7617.07%, a weight percent gain (WPG) of 4.90-18.16%, and a hardness increased by 0.59-1.23% compared to the control group.

Example 3

The contact angles of the wood samples were measured using an optical contact angle 10 measuring instrument (in FIG. 1, a is the contact angle of the control wood, and b is the contact angle of the wood modified by the unsaturated resin). After the modification by the rosin-based unsaturated resin, the contact angle was increased by 47.41-75.68°. At the same time, the dynamic wettability of each of the samples was assessed by collecting the descent angles of the left and right sides at 0.1 second intervals, each sample being measured for 180 seconds, to 15 calculate the average angle, thereby evaluating the dynamic wettability (see FIG. 2). In each group, four samples were tested, 3 drops were captured for each sample, and 12 contact angles were measured.

Claims

1. A method for modification of fast growing wood using a rosin-based unsaturated resin, comprising the steps of impregnating the fast growing wood in a solution of the rosin-based unsaturated resin in ethanol for 22-28 hours, and then removing and drying the fast growing wood, followed by curing, thereby obtaining the fast growing wood modified by the rosinbased unsaturated resin, wherein the solution of the rosin-based unsaturated resin in the ethanol has a mass concentration of 3-25%.

2. The method for the modification of the fast growing wood using the rosin-based unsaturated resin according to claim 1, wherein the rosin-based unsaturated resin is prepared by an esterification reaction of hydrogenated rosin and glycidyl methacrylate, and the solution of the rosin-based unsaturated resin in the ethanol contains AIBN as an initiator with a mass content of 2-4%.

3. The method for the modification of the fast growing wood using the rosin-based unsaturated resin according to claim 1 or 2, wherein the impregnating is carried out at a vacuum of 0.08 to 0.1 MPa for 25 to 50 minutes, and then at atmospheric pressure for 22 to 27 hours.

4. The method for the modification of the fast growing wood using the rosin-based unsaturated resin according to claim 1 or 2, wherein the drying is carried out at a temperature of 45-55°C for 4-6 hours, and the curing is carried out at a temperature of 90-100°C for 2-5 hours, followed by raising the temperature to 130-160°C for post-curing for 1-8 hours, to obtain the fast growing wood modified by the rosin-based unsaturated resin.

5. The method for the modification of the fast growing wood using the rosin-based unsaturated resin according to claim 1 or 2, wherein the fast growing wood modified by the rosin-based unsaturated resin has a density increased by 4.76-17.07%, a weight percent gain (WPG) of 4.90-18.16%, a hardness increased by 0.59-1.23%, and a contact angle increased by 47.41-75.68°, compared with before the modification.