CN110757605A - Method for modifying artificial forest wood by phenol-aldehyde impregnation - Google Patents

Abstract

The invention discloses a method for phenol-aldehyde impregnation of modified plantation wood. The method mainly comprises the steps of: providing negative pressure-impregnating liquid A-applying positive pressure-discharging excess liquid A-providing negative pressure-impregnation of plantation wood Liquid B-applying positive pressure-draining excess liquid B is carried out in a breathing cycle. Liquid A is a mixed liquid composed of phenol, NaOH and water, and liquid B is a formaldehyde solution to obtain phenol-formaldehyde-impregnated modified plantation wood. . By simulating the principle of biological respiration, the method of the invention processes the wood in an alternating cycle of negative pressure exhalation-positive pressure inhalation, which improves the impregnation property of the wood in both directions, significantly improves the impregnation effect and uniformity, and has high reaction efficiency. , and excellent performance.

Description

Method for phenol-aldehyde impregnation of modified plantation wood

technical field

The invention belongs to the technical field of wood functional improvement, and relates to a method for phenol-formaldehyde impregnation and modification of plantation wood, in particular to a method for impregnating and modifying plantation wood with respiratory phenol-formaldehyde oligomers.

Background technique

The area of artificial forests in my country ranks first in the world, with eucalyptus and fir trees in the south and poplar and pine in the north. Due to its fast growth rate and short rotation period, plantation wood has low density and poor quality, and is usually used in low value-added fields such as papermaking and wood-based panels. Functional improvement of plantation wood is an effective way to improve wood performance and added value. At present, the method of pressure impregnation is mainly used to press the modifier into the wood to achieve the purpose of wood reinforcement. However, when impregnating wood, it is difficult for many organic agents to enter the wood, mainly due to the following two reasons: First, because most wood-impregnated organic resins are reactants of "two-step reaction - addition and polycondensation", molecular The polycondensation has been completed in between, forming a macromolecular structure, so it is difficult to enter the wood; secondly, permeability is an important physical property of wood, which will directly affect the process and effect of impregnation modification. Researchers mainly use freezing treatment, steam explosion, microwave treatment and other methods to destroy the tissue structure of wood, thereby improving the permeability of wood. However, this kind of method has high requirements on equipment and technology, which is not convenient for popularization and utilization. In view of the above situation, the development of new methods of modifying plantation wood has become a top priority.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a method for acting on and reacting wood by simulating the principle of biological respiration and taking "negative pressure (exhalation)-positive pressure (inhalation)" as a cycle alternately. A method for phenol-aldehyde impregnation of modified plantation wood with high efficiency, uniform impregnation and excellent performance.

In order to solve the above technical problems, the present invention adopts the following technical solutions.

A method for phenol-aldehyde impregnating modified plantation wood, the method mainly comprises the steps of providing negative pressure-impregnating liquid A-applying positive pressure-discharging excess liquid A-providing negative pressure-impregnating liquid B- The method of applying positive pressure and discharging excess B liquid is carried out for breathing circulation treatment. A liquid is a mixed liquid composed of phenol and NaOH solution, and B liquid is a formaldehyde solution to obtain phenol-formaldehyde impregnation modified plantation wood.

The method for above-mentioned phenol-aldehyde impregnation modified plantation wood, preferably, comprises the following steps:

(1) Put the plantation wood in the reaction container, first vacuumize to form a negative pressure and keep the pressure, so that the air in the wood cell gap is drawn out, then add A liquid to immerse the wood, after the liquid is completed, unload the negative pressure, and then send it to the Positive pressure is applied and maintained in the reaction vessel, so that A liquid is fully immersed in the wood, and then excess A liquid is discharged;

(2) The reaction vessel after the excess liquid A was discharged was first evacuated to form a negative pressure and pressure maintained, so that the air and residual water in the cavity of the wood were extracted, and then liquid B was added to immerse the wood. Unload the negative pressure, and then apply positive pressure to the reaction vessel and maintain the pressure, so that the B liquid is fully immersed in the wood, and then the excess B liquid is discharged;

(3) Taking the treatment process from the above steps (1) to (2) as a breathing cycle, after repeating the cycle for many times, it is cured by vacuum heating to obtain a phenol-aldehyde impregnation modified plantation wood.

The above-mentioned phenol-aldehyde impregnation method for modified plantation wood, preferably, the NaOH solution is composed of NaOH and water, and the mass ratio of the phenol, NaOH, water and formaldehyde solution is 185-190:50-70:70 ～117:240～570, the mass fraction of the formaldehyde solution (ie, the aqueous solution of formaldehyde) is 37%. The mass fraction of the NaOH solution is preferably 30% to 50%.

The above-mentioned phenol-aldehyde impregnation method for modified plantation wood, preferably, the mass ratio of the phenol, NaOH, water and formaldehyde solution is 188.22:50～70:70～117:243.49～568.14.

In the above-mentioned method for impregnating modified plantation wood with phenol-aldehyde, preferably, the preparation process of the liquid A is as follows: dissolving NaOH in water to prepare a NaOH solution, then melting the phenol and mixing it with the NaOH solution uniformly to obtain the liquid A .

In the above-mentioned method of phenol-aldehyde impregnating modified plantation wood, preferably, the plantation wood is first dried to a moisture content of 8% to 12%, and then subjected to a breathing cycle treatment.

In the above-mentioned method of phenol-aldehyde impregnating modified plantation wood, preferably, in the step (1), the vacuum is evacuated to -0.085MPa～-0.1MPa, the negative pressure is maintained for 10min～30min, the positive pressure is It is 0.3MPa ~ 1.1MPa, and the positive pressure is maintained for 30min ~ 50min.

In the above-mentioned method of phenol-aldehyde impregnating modified plantation wood, preferably, in the step (2), the vacuum is evacuated to -0.085MPa～-0.1MPa, the negative pressure is maintained for 10min～30min, the positive pressure is It is 0.3MPa ~ 1.1MPa, and the positive pressure is maintained for 30min ~ 50min.

In the above-mentioned method of phenol-aldehyde impregnating modified plantation wood, preferably, in the step (3), the number of cycles is 1 to 12 times; the temperature of the vacuum heating and curing is 50°C to 80°C , the vacuum heating and curing time is 6h～24h.

In the above-mentioned phenol-aldehyde impregnation method for modifying plantation wood, preferably, the plantation wood includes one or more of fir, eucalyptus, pine and poplar.

Compared with the prior art, the advantages of the present invention are:

(1) The present invention provides a method for impregnating modified plantation wood with respiratory phenolic oligomers, which adopts the reaction raw material of small molecules as impregnating agent, which is combined with a newly designed impregnation process to improve the impregnation of wood in two phases. It can significantly improve the impregnation effect and uniformity, and solve the technical key of impregnating plantation wood. Most of the traditional resin-impregnated modified wood uses a two-step reaction formula (addition reaction and polycondensation reaction) resin, but this resin forms a macromolecular structure due to the completion of polycondensation, which affects its penetration in the wood, resulting in low impregnation efficiency. , the uniformity is poor; the present invention uses phenol and aldehyde small molecular raw materials to impregnate wood, the molecules have not been polycondensed, and the molecular weight is small. Small molecules of phenol-aldehydes penetrate easily and uniformly into wood, which can significantly improve the depth and uniformity of impregnation.

(2) Compared with traditional phenolic resin-impregnated modified wood, the method for impregnating modified wood with respiratory phenol-formaldehyde reduces the curing time of phenol-formaldehyde in wood and improves the effect of impregnation and modification on wood. efficiency.

(3) Compared with the traditional phenolic resin impregnating modified wood, the method for strengthening the wood with breathing phenol-formaldehyde provided by the present invention effectively penetrates the interior of the wood while pushing the modifier into the wood through the circulation of the external pressure. channel, which significantly improves the immersion and uniformity of the modifier in the wood.

(4) The breathable phenol-aldehyde-impregnated modified wood provided by the present invention can not only be used in the fields of furniture, flooring, construction, etc., but can even meet the requirements of modern prefabricated wood structure engineering materials.

Description of drawings

FIG. 1 is a schematic diagram of the principle of the method for phenol-aldehyde impregnation of modified plantation wood in the embodiment of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

The materials and instruments used in the following examples are commercially available.

Example 1

A method for phenol-aldehyde impregnation modified plantation wood of the present invention, as shown in Figure 1, comprises the following steps:

(1) Saw fir wood into a size of 10mm×10mm×200mm, and dry to a moisture content of 12%. Dissolve 50 g of NaOH in 117 g of water, mix with 188.22 g of molten phenol, and prepare liquid A for later use. Put the dried fir wood with a moisture content of 12% into the impregnating tank, vacuum the impregnating tank to -0.085MPa, keep the pressure for 10 minutes, so that the air in the wood cell gap is drawn out, and then the liquid starts to flow through the tank. The negative pressure of the agent A is sucked into the tank without passing the wood. After entering the liquid A, the negative pressure is unloaded, and a positive pressure of 0.5MPa is applied to the tank for 50min. A thrust of the A liquid makes the wood impregnation more complete, and accelerates the impregnation speed, which can effectively shorten the impregnation time and discharge the excess A liquid. The excess A liquid is discharged by the positive pressure in the tank. Generally, when the A liquid is discharged, The positive pressure in the tank has been discharged.

(2) The immersion tank from which liquid A was discharged was first evacuated to form a negative pressure of -0.085MPa, and the pressure was maintained for 10 minutes to remove air and residual water in the wood cell cavity, and then 243.49g of liquid B was added to immerse the wood. Liquid B was The formaldehyde solution with a mass fraction of 37%, unload the negative pressure after entering the liquid B, and then apply a positive pressure of 0.5 MPa to the tank for 50 minutes, so that the liquid B is fully immersed in the wood, and then the excess liquid B is discharged. The excess liquid B is discharged by the positive pressure in the tank.

(3) Take "negative pressure-dipping liquid A-positive pressure-draining liquid A-negative pressure-dipping liquid B-positive pressure-draining liquid B" from the above steps (1) to (2) as a breathing cycle pair Alternate cycle of wood 2 times. The impregnated wood was taken out, the surface was washed with water, and then placed in a vacuum drying oven at 50° C. for 6 hours to solidify to obtain phenol-formaldehyde impregnated modified plantation wood.

Example 2

A method for phenol-aldehyde impregnation modified plantation wood of the present invention, as shown in Figure 1, comprises the following steps:

(1) Saw poplar wood into 20mm×20mm×400mm, and dry to a moisture content of 10%. Dissolve 60 g of NaOH in 90 g of water, melt and mix with 188.22 g of phenol in parts by weight, and prepare liquid A for later use. Put the dried fir wood with a moisture content of 10% into the dipping tank, vacuum the dipping tank to -0.095MPa, keep the pressure for 20min, and then start to enter the liquid, and suck the agent A liquid into the tank through the negative pressure in the tank. There is no wood in it. After entering the liquid A, unload the negative pressure, and then apply a positive pressure of 0.9MPa to the tank for 40 minutes. It can effectively shorten the immersion time and discharge the excess liquid A.

(2) The immersion tank from which liquid A was discharged was first evacuated to form a negative pressure of -0.095MPa, maintained for 20 minutes, and 405.81 g of 37wt% formaldehyde solution in liquid B was added to immerse the wood. After entering liquid B, the negative pressure was unloaded, and then applied to the tank. The positive pressure of 0.9MPa, maintain the pressure for 40min, and then discharge the excess B liquid.

(3) Take "negative pressure-dipping liquid A-positive pressure-draining liquid A-negative pressure-dipping liquid B-positive pressure-draining liquid B" from the above steps (1) to (2) as a breathing cycle pair The wood alternates cycle a total of 6 times. The impregnated wood was taken out, the surface was washed with water, and then put into a vacuum drying oven at 70° C. for 18 hours to solidify to obtain phenol-formaldehyde impregnated modified plantation wood.

Example 3

A method for phenol-aldehyde impregnation modified plantation wood of the present invention, as shown in Figure 1, comprises the following steps:

(1) Saw pine wood into 40mm×40mm×800mm, and dry to a moisture content of 8%. Dissolve 70g of NaOH in 70g of water, melt and mix with 188.22g of phenol in parts by weight, and prepare liquid A for use. Put the dried fir wood with a moisture content of 10% into the dipping tank, vacuum the dipping tank to -0.1MPa, keep the pressure for 30min, and then start to enter the liquid, and suck the agent A liquid into the tank through the negative pressure in the tank. There is no wood in it. After entering the liquid A, unload the negative pressure, and then apply a positive pressure of 1.1 MPa to the tank for 30 minutes. Completely, and accelerate the speed of dipping, which can effectively shorten the dipping time; discharge the excess liquid A.

(2) The immersion tank from which the liquid A was discharged was first evacuated to form a negative pressure of -0.1MPa, maintained for 30 minutes, and 568.14 g of a 37wt% formaldehyde solution in liquid B was added to immerse the wood. After entering liquid B, the negative pressure was unloaded, and then applied to the tank. The positive pressure of 1.1MPa is maintained for 30min, and then the excess B liquid is discharged.

(3) Take "negative pressure-dipping liquid A-positive pressure-draining liquid A-negative pressure-dipping liquid B-positive pressure-draining liquid B" as a breathing cycle, and cycle the wood alternately for a total of 12 times. The impregnated wood was taken out, the surface was washed with water, and then put into a vacuum drying oven at 70°C for curing for 24 h to obtain phenol-formaldehyde impregnated modified plantation wood.

The test results of various properties of the above-mentioned Example 1, Example 2, Example 3 and unmodified wood are shown in Table 1. It can be seen from the test results that the wood weight and density are significantly increased after phenol-aldehyde modification, which indicates that the phenol-aldehyde has been successfully impregnated into the wood. At the same time, the mechanical strength of the modified wood is also significantly better than that of the unmodified wood, which further indicates that the phenol-aldehyde has been successfully impregnated into the wood, and undergoes a polymerization and curing reaction to generate macromolecular phenolic resin, which then fills the wood cavity. , to enhance the mechanical properties of wood.

Table 1 Comparison of properties of phenol-aldehyde modified wood

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the spirit and technical solutions of the present invention, can make many possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above, or modify them to be equivalent. Variant equivalent embodiments. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims (10)

1. A method for impregnating and modifying artificial forest wood by phenol-aldehyde is characterized in that the artificial forest wood is subjected to respiratory cycle treatment in a mode of providing negative pressure, impregnating liquid A, applying positive pressure, discharging redundant liquid A, providing negative pressure, impregnating liquid B, applying positive pressure and discharging redundant liquid B, the liquid A is a mixed liquid composed of phenol and NaOH solution, and the liquid B is formaldehyde solution, so that the artificial forest wood impregnated and modified by phenol-aldehyde is obtained.

2. The method of phenol-aldehyde impregnation of modified forest wood according to claim 1, comprising the steps of:

(1) placing the artificial forest wood in a reaction container, vacuumizing to form negative pressure and maintaining the pressure to pump out air in gaps of wood cells, adding the solution A to immerse the wood, unloading the negative pressure after liquid inlet is finished, applying positive pressure and maintaining the pressure in the reaction container to fully immerse the solution A in the wood, and discharging redundant solution A;

(2) vacuumizing the reaction container with the discharged redundant liquid A to form negative pressure and maintaining the pressure, pumping out air and residual moisture in gaps of wood cell cavities, adding the liquid B to immerse the wood, unloading the negative pressure after liquid inlet is finished, applying positive pressure and maintaining the pressure in the reaction container to fully immerse the liquid B in the wood, and discharging the redundant liquid B;

(3) and (3) performing one-time breathing type circulation in the treatment process from the step (1) to the step (2), repeating the circulation for multiple times, and performing vacuum heating and curing to obtain the phenol-aldehyde impregnated and modified artificial forest wood.

3. The method for impregnating and modifying artificial forest wood by phenol-aldehyde according to claim 1 or 2, wherein the NaOH solution is composed of NaOH and water, the mass ratio of the phenol, the NaOH, the water and the formaldehyde solution is 185-190: 50-70: 70-117: 240-570, and the mass fraction of the formaldehyde solution is 37%.

4. The method for phenol-aldehyde impregnation modification of artificial forest wood according to claim 3, wherein the mass ratio of the phenol, NaOH, water and formaldehyde solution is 188.22: 50-70: 70-117: 243.49-568.14.

5. The method for phenol-aldehyde impregnation of modified forest wood according to claim 3, wherein the solution A is prepared by: and dissolving NaOH in water to prepare a NaOH solution, and then melting phenol and uniformly mixing with the NaOH solution to obtain solution A.

6. The method for impregnating and modifying the wood of the artificial forest according to the phenol-aldehyde according to the claim 1 or 2, wherein the wood of the artificial forest is dried to the water content of 8-12% and then is subjected to the respiratory cycle treatment.

7. The method for phenol-aldehyde impregnation of modified artificial forest wood according to claim 2, wherein in the step (1), the vacuum is applied to-0.085 MPa to-0.1 MPa, the negative pressure is maintained for 10min to 30min, the positive pressure is 0.3MPa to 1.1MPa, and the positive pressure is maintained for 30min to 50 min.

8. The method for phenol-aldehyde impregnation of modified artificial forest wood according to claim 2, characterized in that, in the step (2), the vacuum is pumped to-0.085 MPa to-0.1 MPa, the negative pressure is maintained for 10min to 30min, the positive pressure is 0.3MPa to 1.1MPa, and the positive pressure is maintained for 30min to 50 min.

9. The method for phenol-aldehyde impregnation of modified forest wood according to claim 2, wherein in the step (3), the number of the cycles is 1 to 12; the temperature of the vacuum heating curing is 50-80 ℃, and the time of the vacuum heating curing is 6-24 h.

10. The method of phenol-aldehyde impregnation of modified forest wood according to claim 1 or 2, wherein the forest wood comprises one or more of fir, eucalyptus, pine and poplar.

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