CN112045810A

CN112045810A - Treatment process for improving mechanical property of fast-growing poplar

Info

Publication number: CN112045810A
Application number: CN202010852990.7A
Authority: CN
Inventors: 孙传标
Original assignee: Funan Jiasheng Willow Handicraft Co ltd
Current assignee: Funan Jiasheng Willow Handicraft Co ltd
Priority date: 2020-08-22
Filing date: 2020-08-22
Publication date: 2020-12-08

Abstract

The invention discloses a treatment process for improving the mechanical property of fast-growing poplar; relates to the technical field of wood treatment, and comprises the following steps: (1) processing a plate; (2) carrying out high-temperature pressurization primary treatment; (3) carrying out reaction treatment; (4) carrying out high-temperature pressurization secondary treatment; the method for treating the fast-growing poplar can obviously improve the performance of the fast-growing poplar, and can show that the loose structure of the treated fast-growing poplar is obviously densified and improved by increasing the weight of the fast-growing poplar, so that the mechanical property, particularly the strength property, can be obviously improved, the application range of the fast-growing poplar can be obviously improved, and the weight gain rate of the fast-growing poplar can be obviously improved by adding a certain amount of rare earth chloride.

Description

Treatment process for improving mechanical property of fast-growing poplar

Technical Field

The invention belongs to the technical field of wood treatment, and particularly relates to a treatment process for improving the mechanical property of fast-growing poplar.

Background

The area of the artificial forest in China is about 0.69 hundred million hectares, 24.83 billion cubic meters are accumulated, the area of the artificial forest is enabled to be at the top of the world by long-term investment of the area of the artificial forest, meanwhile, the contradiction between effective supply of the forest and the increasing social demand is still outstanding, high-quality wood is seriously dependent on import, the external dependence is higher, and the safety situation of the wood is more severe.

The fast-growing poplar in China has the advantages of abundant resources, wide distribution, large amount of planting in a plurality of regions, large planting area of poplar in China, wide distribution, convenient material taking, high growth speed, capability of being grown in five years, strong adaptability and capability of being widely applied to industries such as plywood, shaving boards, papermaking pulp and the like.

However, the fast-growing poplar has the characteristics of loose microstructure, low strength, large deformation and the like due to fast growth, so that the application of the fast-growing poplar is limited.

Disclosure of Invention

The invention aims to provide a treatment process for improving the mechanical property of fast-growing poplar, so as to solve the defects in the prior art.

The technical scheme adopted by the invention is as follows:

a treatment process for improving the mechanical property of fast-growing poplar wood comprises the following steps:

(1) plate processing:

processing poplar logs to prepare poplar boards;

(2) high-temperature pressurization primary treatment:

performing high-temperature pressurization treatment on the obtained poplar board for one time, placing the poplar board at a high temperature and a high pressure for one time, standing for 40-50min, and then taking out;

(3) reaction treatment:

soaking the poplar board subjected to high-temperature pressurization primary treatment into a furfural solution, soaking at normal temperature for 30-35min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 60-65 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reacted poplar board;

(4) carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 2-3 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board.

The thickness of the poplar board is 1 cm.

The high temperature under the primary high temperature and high pressure is 150-155 ℃;

the high pressure under the primary high temperature and high pressure is 0.38-0.45 MPa.

The high temperature under the primary high temperature and high pressure is 152 ℃;

the high pressure under the primary high temperature and high pressure is 0.41 MPa.

The mass fraction of the furfural solution is 55-58%;

the molar ratio of the maleic anhydride to the citric acid is 15: 1-1.5;

the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2.

The heating rate of the slow heating is 0.5 ℃/min.

The high temperature under the secondary high temperature and high pressure is 135-140 ℃;

the high pressure under the secondary high temperature and high pressure is 0.60-0.68 MPa.

The high temperature under the secondary high temperature and high pressure is 138 ℃;

the high pressure under the secondary high temperature and high pressure is 0.65 MPa.

The invention can also add a small amount of rare earth chloride in the furfural solution in advance, and then add maleic anhydride and citric acid;

the adopted rare earth chloride is cerium chloride;

the mass fraction of cerium chloride in the furfural solution is 0.012%.

According to the invention, a small amount of cerium chloride is added in the furfural solution in advance, so that furfural can be promoted to polymerize, and simultaneously, the furfural is tightly combined with cellulose, hemicellulose and the like in poplar wood, and simultaneously, the furfural and lignin are subjected to a cross-linking reaction, so that the binding force is improved, the weight gain rate of poplar wood can be obviously improved, and the obvious improvement of the weight gain rate of poplar wood indicates that the polymerization degree of furfural in poplar wood is greatly improved, so that the mechanical property of poplar wood can be better improved.

Has the advantages that:

the method for treating the fast-growing poplar can obviously improve the performance of the fast-growing poplar, and can show that the loose structure of the treated fast-growing poplar is obviously densified and improved by increasing the weight of the fast-growing poplar, so that the mechanical property, particularly the strength property, can be obviously improved, the application range of the fast-growing poplar can be obviously improved, and the weight gain rate of the fast-growing poplar can be obviously improved by adding a certain amount of rare earth chloride.

The method of the invention combines the high-temperature high-pressure primary treatment and the secondary treatment, can obviously improve the dimensional stability of the treated fast-growing poplar and reduce the dry shrinkage rate, and improves the comprehensive performance of the fast-growing poplar, thereby improving the application range of the fast-growing poplar.

According to the invention, a certain amount of cerium chloride is added, so that the weight gain rate of the treated fast-growing poplar can be obviously improved, the mechanical property of the fast-growing poplar can be improved, the weight gain rate of the fast-growing poplar can be directly influenced by adjusting the addition amount of the cerium chloride, and the weight gain rate of the fast-growing poplar is actually influenced by influencing the combination stability between the polymerized furfural and the tissue of the fast-growing poplar.

Detailed Description

(1) plate processing:

processing poplar logs to prepare poplar boards;

(2) high-temperature pressurization primary treatment:

(3) reaction treatment:

soaking the poplar board subjected to high-temperature pressurization primary treatment into a furfural solution, soaking at normal temperature for 30-35min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 60-65 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reacted poplar board; after the high-temperature pressurization treatment for one time, the tissue gaps of the fast-growing poplar can be relaxed, then the reaction treatment is carried out, so that the reaction liquid is promoted to permeate into the fast-growing poplar, the cell filling effect on the interior of the fast-growing poplar is better, and meanwhile, because the furfuryl alcohol has a small molecular weight, the furfuryl alcohol can enter the cell wall of the fast-growing poplar, and after the furfuryl alcohol is solidified, the cell wall gaps are filled, so that the porosity is reduced, and the weight of the fast-growing poplar is improved;

maleic anhydride:

melting point 52.8 ℃;

boiling point is 202 ℃;

dissolving water soluble maleic acid in water to obtain maleic acid;

density 1.480g/cm^₃；

An orthorhombic colorless needle-like or plate-like crystal in appearance;

the flash point is 103 ℃;

furfural, also known as 2-furaldehyde, is the same substance as furfural. Its chemical name is alpha-furaldehyde, which is a derivative in which the hydrogen atom at position 2 of furan is replaced by an aldehyde group. It was originally made from rice bran co-heated with dilute acid and is called furfural. The furfural is prepared by hydrolyzing pentosan under the action of acid to generate pentose, and then dehydrating and cyclizing the pentose. The main raw materials of the production are agricultural and sideline products such as corncobs and the like. There are various synthetic methods. Furfural is the most important derivative of furan ring system, has active chemical property, and can prepare a plurality of derivatives through oxidation, condensation and other reactions;

(4) carrying out high-temperature pressurization secondary treatment;

The thickness of the poplar board is 1 cm.

The mass fraction of the furfural solution is 55-58%;

the molar ratio of the maleic anhydride to the citric acid is 15: 1-1.5;

The heating rate of the slow heating is 0.5 ℃/min.

The following will clearly and completely describe the technical solutions of the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

(1) plate processing:

processing poplar logs to prepare poplar boards; the thickness of the poplar board is 1 cm.

(2) High-temperature pressurization primary treatment:

carrying out high-temperature pressurization once treatment on the obtained poplar board, placing the poplar board at once high-temperature and high-pressure, standing for 40min, and then taking out; the high temperature under the primary high temperature and high pressure is 150 ℃; the high pressure under the primary high temperature and high pressure is 0.38 MPa.

(3) Reaction treatment:

soaking the poplar board subjected to high-temperature pressurization once treatment into a furfural solution, soaking at normal temperature for 30min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 60 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reacted poplar board; the mass fraction of the furfural solution is 55%; the molar ratio of the maleic anhydride to the citric acid is 15: 1; the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2. The heating rate of the slow heating is 0.5 ℃/min.

(4) Carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 2 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board. The high temperature under the secondary high temperature and high pressure is 135 ℃; the high pressure under the secondary high temperature and high pressure is 0.60 MPa.

Example 2

(1) plate processing:

(2) High-temperature pressurization primary treatment:

carrying out high-temperature pressurization once treatment on the obtained poplar board, placing the poplar board at once high-temperature and high-pressure, standing for 50min, and then taking out the poplar board; the high temperature under the primary high temperature and high pressure is 155 ℃; the high pressure under the primary high temperature and high pressure is 0.45 MPa.

(3) Reaction treatment:

soaking the poplar board subjected to high-temperature pressurization primary treatment into a furfural solution, soaking at normal temperature for 35min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 65 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reacted poplar board; the mass fraction of the furfural solution is 58%; the molar ratio of the maleic anhydride to the citric acid is 15: 1.5; the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2. The heating rate of the slow heating is 0.5 ℃/min.

(4) Carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 3 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board. The high temperature under the secondary high temperature and high pressure is 140 ℃; the high pressure under the secondary high temperature and high pressure is 0.68 MPa.

Example 3

(1) plate processing:

(2) High-temperature pressurization primary treatment:

carrying out high-temperature pressurization once treatment on the obtained poplar board, placing the poplar board at once high-temperature and high-pressure, standing for 42min, and then taking out; the high temperature under the primary high temperature and high pressure is 152 ℃; the high pressure under the primary high temperature and high pressure is 0.41 MPa.

(3) Reaction treatment:

soaking the poplar board subjected to high-temperature pressurization once treatment into a furfural solution, soaking at normal temperature for 33min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 63 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reacted poplar board; the mass fraction of the furfural solution is 57%; the molar ratio of the maleic anhydride to the citric acid is 15: 1.2; the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2. The heating rate of the slow heating is 0.5 ℃/min.

(4) Carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 2.5 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board. The high temperature under the secondary high temperature and high pressure is 138 ℃; the high pressure under the secondary high temperature and high pressure is 0.62 MPa.

Example 4

(1) plate processing:

(2) High-temperature pressurization primary treatment:

carrying out high-temperature pressurization once treatment on the obtained poplar board, placing the poplar board at once high-temperature and high-pressure, standing for 45min, and then taking out; the high temperature under the primary high temperature and high pressure is 152 ℃;

(3) Reaction treatment:

soaking the poplar boards subjected to high-temperature pressurization primary treatment into a furfural solution, and adding rare earth chloride, wherein the adopted rare earth chloride is cerium chloride;

the cerium chloride accounts for 0.012 percent of the mass of the furfural solution, is soaked at normal temperature for 32min, then is added with maleic anhydride and citric acid, is stirred and reacts for 2 hours, is slowly heated to 63 ℃, is continuously soaked for 1 hour, is taken out, and is drained on the surface to obtain a reaction poplar board; the mass fraction of the furfural solution is 56%; the molar ratio of the maleic anhydride to the citric acid is 15: 1.2; the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2. The heating rate of the slow heating is 0.5 ℃/min.

(4) Carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 2.3 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board. The high temperature under the secondary high temperature and high pressure is 138 ℃; the high pressure under the secondary high temperature and high pressure is 0.65 MPa.

Example 5

(1) plate processing:

(2) High-temperature pressurization primary treatment:

(3) Reaction treatment:

(4) Carrying out high-temperature pressurization secondary treatment;

Processing the same batch of poplar into poplar boards with the same specification for testing;

the weight gain ratio M = (M1-M2)/M2 × 100%;

m: weight gain,%;

m 1: oven dry mass of sample after treatment, g;

m 2: absolute dry mass, g, of the sample before treatment;

TABLE 1

	The weight gain rate%
		Example 1	53.16
Example 2	52.10
		Example 3	55.05
Example 4	57.87
		Example 5	66.72
Comparative example 1	41.46

Comparative example 1: the fast growing poplar wood treating process includes the following steps:

(1) plate processing:

(2) Reaction treatment:

soaking a poplar board in a furfural solution, soaking at normal temperature for 30min, adding maleic anhydride and citric acid, stirring for reacting for 2 hours, slowly heating to 60 ℃, continuing to soak for 1 hour, taking out, and draining the surface to obtain a reaction poplar board; the mass fraction of the furfural solution is 55%; the molar ratio of the maleic anhydride to the citric acid is 15: 1; the molar ratio of the furfural to the maleic anhydride in the furfural solution is 1: 2. The heating rate of the slow heating is 0.5 ℃/min.

(3) Carrying out high-temperature pressurization secondary treatment;

and (3) carrying out high-temperature pressurization secondary treatment on the obtained reaction poplar board, placing the poplar board at secondary high-temperature high-pressure, standing for 2 hours, then gradually reducing the temperature to room temperature at the speed of 1 ℃/min, and taking out the poplar board. The high temperature under the secondary high temperature and high pressure is 135 ℃; the high pressure under the secondary high temperature and high pressure is 0.60 MPa;

as can be seen from table 1, the treatment of the fast-growing poplar by the method of the present invention can significantly improve the performance of the fast-growing poplar, and the increase of the weight of the fast-growing poplar can indicate that the loose structure of the treated fast-growing poplar is significantly increased in densification, so that the mechanical properties, especially the strength property, can be significantly increased, the application range of the fast-growing poplar can be significantly increased, and the weight gain of the fast-growing poplar can be significantly increased by adding a certain amount of rare earth chloride.

By taking the example 5 as a basic sample, comparing the influence of different cerium chloride addition amounts on the weight gain rate of the treated poplar;

the cerium chloride accounts for the mass fraction of the furfural solution;

TABLE 2

Cerium chloride accounts for the mass fraction of the furfural solution	The weight gain rate%
		0.004	59.28
0.008	61.17
		0.012	66.72
0.014	66.05

As can be seen from table 2, the weight gain of treated fast-growing poplar can be significantly increased by adding a certain amount of cerium chloride, so that the mechanical properties of fast-growing poplar can be improved, the weight gain of fast-growing poplar can be directly influenced by adjusting the addition amount of cerium chloride, and the weight gain of fast-growing poplar can be substantially influenced by influencing the bonding stability between furfural polymerized and fast-growing poplar tissues.

Dimensional stability

According to the regulation in GB/T1932-2009 method for measuring the drying shrinkage of wood, the size of the test sample from a wet material to air drying and from the wet material to full drying is tested, and further the volume drying shrinkage is calculated;

TABLE 3

	The dry shrinkage rate of the wet wood to the air-dry volume%	Wet wood to full dry volume dry shrinkage%
			Example 1	3.875	8.683
Example 2	3.821	8.619
			Example 3	3.715	8.588
Example 4	3.529	8.316
			Example 5	3.025	7.986
Blank control group	9.034	11.725

As can be seen from Table 3, the volume drying shrinkage of the treated fast-growing poplar can be greatly reduced by treating the fast-growing poplar by the method disclosed by the invention, which shows that the dimensional stability of the fast-growing poplar treated by the method disclosed by the invention is greatly improved.

The influence of whether the pressure treatment is carried out or not on the dry shrinkage is compared by using the sample as the base sample in example 5;

a, when high-temperature and high-pressure primary treatment is carried out, no pressurization is carried out;

b, when the high-temperature high-pressure secondary treatment is carried out, no pressurization is carried out;

c, when the high-temperature high-pressure treatment is carried out for one time, no pressurization is carried out; when the high-temperature high-pressure secondary treatment is carried out, no pressurization is carried out;

TABLE 4

	The dry shrinkage rate of the wet wood to the air-dry volume%	Wet wood to full dry volume dry shrinkage%
			A	3.201	8.115
B	3.752	8.696
			C	3.818	8.793

As can be seen from Table 4, the method of the present invention, through the combination of the primary treatment and the secondary treatment at high temperature and high pressure, can significantly improve the dimensional stability of the treated fast-growing poplar, reduce the dry shrinkage rate, and improve the comprehensive performance of the fast-growing poplar, thereby increasing the application range thereof.

Detecting the hardness of the treated fast-growing poplar according to GB/T1941-2009 Wood hardness test method;

TABLE 5

	Wet to air dry bulk hardness/N
		Example 1	3833
Example 2	3725
		Example 3	3917
Example 4	4011
		Example 5	4325
Blank control group	1995

As can be seen from Table 5, the hardness of the fast-growing poplar treated by the method of the present invention was greatly increased.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention, and the present invention is not limited to the illustrated embodiments, and all the modifications and equivalents of the embodiments may be made without departing from the spirit of the present invention.

Claims

1. A treatment process for improving the mechanical property of fast-growing poplar is characterized by comprising the following steps:

(1) plate processing:

processing poplar logs to prepare poplar boards;

(2) high-temperature pressurization primary treatment:

(3) reaction treatment:

(4) carrying out high-temperature pressurization secondary treatment;

2. The treatment process for improving the mechanical property of fast-growing poplar according to claim 1, wherein the treatment process comprises the following steps: the thickness of the poplar board is 1 cm.

3. The treatment process for improving the mechanical property of fast-growing poplar according to claim 1, wherein the treatment process comprises the following steps: the high temperature under the primary high temperature and high pressure is 150-155 ℃;

4. The treatment process for improving the mechanical properties of fast-growing poplar according to claim 3, wherein the treatment process comprises the following steps: the high temperature under the primary high temperature and high pressure is 152 ℃;

5. The treatment process for improving the mechanical property of the fast-growing poplar according to claim 1, which is characterized by comprising the following steps of: the mass fraction of the furfural solution is 55-58%;

the molar ratio of the maleic anhydride to the citric acid is 15: 1-1.5;

6. The treatment process for improving the mechanical property of the fast-growing poplar according to claim 1, which is characterized by comprising the following steps of: the heating rate of the slow heating is 0.5 ℃/min.

7. The treatment process for improving the mechanical property of fast-growing poplar according to claim 1, wherein the treatment process comprises the following steps: the high temperature under the secondary high temperature and high pressure is 135-140 ℃;

8. The treatment process for improving the mechanical properties of fast-growing poplar according to claim 7, wherein the treatment process comprises the following steps: the high temperature under the secondary high temperature and high pressure is 138 ℃;