A method for controlling the color of high-performance reconstituted wood

Abstract

The present invention discloses a method for color control of high-performance reconstituted wood: (1) soaking a debonded veneer in a ligand solution, wherein the ligand solution is an ammonium acetate and / or ethylenediaminetetraacetic acid solution; (2) drying the veneer until the moisture content is less than 10%; (3) impregnating the veneer with an adhesive containing trivalent iron ions and draining the veneer; (4) drying the veneer until the moisture content is 20-25% and aging the veneer; (5) hot-pressing the debonded veneer into reconstituted wood after aging; (6) controlling the moisture content of the reconstituted wood to 7-13% after moisture conditioning, thereby obtaining high-performance reconstituted wood. The present invention can obtain a standard reconstituted wood that meets the market's "redwood" aesthetic requirements by soaking the debonded veneer in a ligand solution and adjusting the adhesive composition and content, the moisture content after dipping, the hot pressing temperature, and other processes. The method is simple, safe, and does not cause environmental pollution problems caused by coloring methods such as dyeing.

Description

Technical Field

[0001] The invention relates to the technical field of reconstituted wood, and in particular to a method for controlling the color of high-performance reconstituted wood. Background Art

[0002] Wood color is a key indicator of wood's surface properties and commercial value. High-performance reconstituted wood, a breakthrough, high-value-added product that maximizes the potential of small materials and improves the quality of inferior materials, maintains its natural grain while possessing physical and mechanical properties exceeding those of premium hardwood. However, reconstituted wood, primarily derived from fast-growing plantation timber, results in a monotonous color and fails to meet the market's aesthetic standards for "rosewood." Therefore, regulating the color of reconstituted wood can improve the appearance, decorative effect, and economic value of reconstituted wood products.

[0003] Previously, Professor Gao Jianmin's team at Beijing Forestry University used metal coordination reactions, Maillard reactions, and thermal media coloring to achieve targeted color control of Eucalyptus grandis × E.urophylla and Robinia Psoudoaacacia toward Pterocarpus Macarocarpus Kurz. While these processes are more environmentally friendly than traditional dyeing methods, these methods cannot improve the loose texture and poor mechanical strength of fast-growing wood. Summary of the Invention

[0004] In order to solve the problems in the existing technology that reconstructed wood dyeing is mostly done by dye or paint, which causes environmental pollution, and the traditional methods cannot improve the defects of fast-growing wood such as loose material and poor mechanical strength, the present invention attempts to combine the redwood material color control technology of fast-growing wood with reconstructed wood, and realizes the redwoodization and efficient value-added of high-performance reconstructed wood in the process of releasing the veneer state and even hot pressing and curing.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A high-performance method for color control of reconstituted wood comprises the following steps:

[0007] (1) A decomposed veneer prepared by decomposing a fast-growing rotary-cut veneer is used as a basic unit; the decomposed veneer is immersed in a ligand solution, wherein the ligand solution is an ammonium acetate and / or ethylenediaminetetraacetic acid solution, and the concentration of the ammonium acetate and / or ethylenediaminetetraacetic acid solution in the ligand solution is 0.1-0.3 mol / L. When the ligand solution is a mixture of ammonium acetate and ethylenediaminetetraacetic acid solution, the ratio of the two solutions is arbitrary, as long as the concentration obtained by mixing the two solutions is 0.1-0.3 mol / L;

[0008] (2) drying the decomposed veneer after being immersed in the ligand solution in step (1) until the moisture content is less than 10%;

[0009] (3) impregnating the dried decomposed veneer with an adhesive containing trivalent iron ions and draining; wherein the adhesive containing trivalent iron ions is an adhesive in which a metal salt of trivalent iron ions is added, and the mass ratio of the trivalent iron ion metal salt to the adhesive is 1:100-1:200;

[0010] (4) drying the drained veneer to a moisture content of 20-25% and aging;

[0011] (5) After aging for 23-24 hours, the debonded veneer is kept at a temperature of 140°C-160°C and hot pressed into reconstituted wood;

[0012] (6) After humidity and conditioning, the moisture content of the reconstituted wood is controlled at 7-13%, thus obtaining high-performance reconstituted wood.

[0013] Wherein, in step (1), the decomposed veneer is immersed in the ligand solution for 5 to 10 minutes.

[0014] Wherein, the metal salt of trivalent iron ion described in step (3) is ferric chloride (FeCl3) or ferric sulfate (Fe2(SO4)3).

[0015] Wherein, the adhesive described in step (3) is a phenolic resin adhesive.

[0016] Wherein, the immersion time in step (3) is 10 to 15 minutes.

[0017] Wherein, the drying temperature described in step (4) is 60-70°C.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention makes improvements on the debonded veneer and the adhesive, giving full play to the advantage of the large penetration depth of the debonded veneer adhesive of the reconstituted wood, combining the degree of densification and high temperature during the hot pressing process, and utilizing metal coordination to make the overall color of the reconstituted wood "rosewood-like"; further, the present invention can obtain a standard reconstituted wood that meets the market's "rosewood-like" aesthetic by soaking the debonded veneer in a ligand solution, adjusting the adhesive composition and content, the moisture content after dipping, the hot pressing temperature and other processes. The method of the present invention is simple, safe and will not cause environmental pollution problems caused by coloring methods such as dyeing. DETAILED DESCRIPTION

[0020] The following is a detailed description of the present invention in conjunction with the specific embodiments, but it should be understood that the scope of the present invention is not limited by the specific embodiments. Unless otherwise specified, the raw materials and reagents used in the examples are all commercially available. The phenolic resin adhesive used in the examples is a commercially available phenolic resin adhesive with the model number NPPN-631.

[0021] Example 1

[0022] A method for high-performance reconstituted wood color control, the operating steps are as follows:

[0023] (1) Using the decomposed veneer made from the decomposition of fast-growing wood rotary cut veneer as the basic unit, the decomposed veneer was immersed in a ligand solution for 5 to 10 minutes. The ligand solution was ammonium acetate with a concentration of 0.1 mol / L.

[0024] (2) drying the decomposed veneer after being immersed in the ligand solution in step (1) at a temperature of 103° C. until the moisture content is less than 10%;

[0025] (3) The dried decomposed veneer is impregnated with a phenolic resin adhesive containing trivalent iron ions for 10 to 15 minutes and then drained for 10 minutes; wherein the phenolic resin adhesive containing trivalent iron ions is prepared by adding ferric chloride (FeCl3) to the adhesive, and the mass ratio of ferric chloride (FeCl3) to the phenolic resin adhesive is 1:100;

[0026] (4) drying the drained veneer at 60-70° C. to a moisture content of 20-25%, and aging;

[0027] (5) After aging for 24 hours, the debonded veneer is kept at 140°C and hot pressed into reconstituted wood, with the hot pressing lasting 1 minute per millimeter of thickness.

[0028] (6) After humidity and conditioning, the moisture content of the reconstituted wood is controlled at 7-13%, thus obtaining high-performance reconstituted wood.

[0029] Example 2

[0030] A method for high-performance reconstituted wood color control, the operating steps are as follows:

[0031] (1) Using a decomposed veneer made by decomposing a fast-growing material rotary cut veneer as a basic unit, the decomposed veneer is immersed in a ligand solution for 5 to 10 minutes. The ligand solution is obtained by mixing ammonium acetate and ethylenediaminetetraacetic acid solution in any proportion. After mixing, the concentration of the solutes ammonium acetate and ethylenediaminetetraacetic acid is 0.2 mol / L;

[0032] (2) drying the decomposed veneer after being immersed in the ligand solution in step (1) at a temperature of 103° C. until the moisture content is less than 10%;

[0033] (3) The dried decomposed veneer is impregnated with a phenolic resin adhesive containing trivalent iron ions for 10 to 15 minutes and then drained for 10 minutes; wherein the phenolic resin adhesive containing trivalent iron ions is prepared by adding ferric chloride (FeCl3) to the adhesive, and the mass ratio of ferric chloride (FeCl3) to the phenolic resin adhesive is 1:151;

[0034] (4) drying the drained veneer at 60-70° C. to a moisture content of 20-25%, and aging;

[0035] (5) After aging for 24 hours, the debonded veneer is kept at 150°C and hot pressed into reconstituted wood, with the debonded veneer being hot pressed for 1 minute per millimeter of thickness;

[0036] (6) After humidity and conditioning, the moisture content of the reconstituted wood is controlled at 7-13%, thus obtaining high-performance reconstituted wood.

[0037] Example 3

[0038] A method for high-performance reconstituted wood color control, the operating steps are as follows:

[0039] (1) Using a decomposed veneer made from a fast-growing wood rotary cut veneer as a basic unit, the decomposed veneer is immersed in a ligand solution for 5 to 10 minutes. The ligand solution is an ethylenediaminetetraacetic acid solution with a concentration of 0.3 mol / L.

[0040] (2) drying the decomposed veneer after being immersed in the ligand solution in step (1) at a temperature of 103° C. until the moisture content is less than 10%;

[0041] (3) The dried decomposed veneer is impregnated with a phenolic resin adhesive containing trivalent iron ions for 10 to 15 minutes and then drained for 10 minutes; wherein the phenolic resin adhesive containing trivalent iron ions is prepared by adding iron sulfate (Fe2(SO4)3) to the adhesive, and the mass ratio of iron sulfate (Fe2(SO4)3) to the phenolic resin adhesive is 1:200;

[0042] (4) drying the drained veneer at 60-70° C. to a moisture content of 20-25%, and aging;

[0043] (5) After aging for 24 hours, the debonded veneer is kept at 160°C and hot pressed into reconstituted wood, with the hot pressing lasting 1 minute per millimeter of thickness.

[0044] (6) After humidity and conditioning, the moisture content of the reconstituted wood is controlled at 7-13%, thus obtaining high-performance reconstituted wood.

[0045] Comparative Example 1

[0046] (1) The basic unit is the debonded veneer made from the debonded veneer of fast-growing wood;

[0047] (2) The decomposed veneer is dried at 103° C. until the moisture content is less than 10%. The remaining operations are the same as those in Example 2.

[0048] Comparative Example 2

[0049] In step (3), the dried decomposed veneer is impregnated with a phenolic resin adhesive (a phenolic resin adhesive that does not contain trivalent iron ions) for 10 to 15 minutes and then drained for 10 minutes; the remaining operations are the same as in Example 2.

[0050] Comparative Example 3

[0051] After aging for 24 hours in step (5), the debonded veneer is cold-pressed at room temperature into reconstituted wood, with the debonded veneer being cold-pressed for 1 minute per millimeter of thickness; the remaining operations are the same as in Example 2.

[0052] Comparative Example 4

[0053] After aging for 24 hours in step (5), the decomposed veneer is kept at a temperature of 130° C. and hot pressed into reconstituted wood, with the decomposed veneer being hot pressed for 1 minute per millimeter of thickness; the remaining operations are the same as in Example 2.

[0054] The surface chromaticity coordinates L* (brightness), a* (redness-greenness index) and b* (yellowness-blueness index) of the reconstituted wood obtained in Examples 1-3 and Comparative Examples 1-4 were measured using a fully automatic colorimeter. According to the changes in the chromaticity coordinates before and after treatment: ΔL, Δa, Δb, the formula: ΔE = (ΔL 2 +Δa 2 +Δb 2 ) 1 / 2 The total color difference of the sample surface before and after treatment was calculated, and the results are shown in Table 1 below:

[0055] Table 1 Color difference results of various embodiments

[0056]

[0057]

[0058] It can be seen from the above table that the color of the reconstituted wood obtained by adjusting the color of the reconstituted wood by the method of the present invention is closer to the level of "rosewood".

[0059] The foregoing descriptions of specific exemplary embodiments of the present invention are for purposes of illustration and description. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many variations and modifications are possible in light of the foregoing teachings. The exemplary embodiments have been selected and described for the purpose of explaining the specific principles of the invention and their practical application, thereby enabling those skilled in the art to realize and utilize a variety of exemplary embodiments of the invention and various options and modifications. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for controlling the color of high-performance reconstituted wood, characterized in that: The following steps are included: (1) Using a debonded veneer made by debonding a fast-growing wood rotary cut veneer as a basic unit; soaking the debonded veneer in a ligand solution, wherein the ligand solution is an ammonium acetate and / or ethylenediaminetetraacetic acid solution, and the concentration of the ammonium acetate and / or ethylenediaminetetraacetic acid solution in the ligand solution is 0.1-0.3 mol / L; (2) drying the decomposed veneer after being immersed in the ligand solution in step (1) until the moisture content is less than 10%; (3) impregnating the dried decomposed veneer with an adhesive containing trivalent iron ions and draining; wherein the adhesive containing trivalent iron ions is an adhesive in which a metal salt of trivalent iron ions is added, and the mass ratio of the trivalent iron ion metal salt to the adhesive is 1:100-1:200; and the metal salt of trivalent iron ions is ferric chloride or ferric sulfate; (4) Drying the drained veneer to a moisture content of 20-25% and aging; (5) After aging for 23-24 hours, the debonded veneer is kept at a temperature of 140℃-160℃ and hot pressed into reconstituted wood; (6) After humidity and conditioning, the moisture content of the reconstituted wood is controlled at 7-13%, thus obtaining high-performance reconstituted wood.

2. The method for color control of high-performance reconstituted wood according to claim 1, wherein: In step (1), the decomposed veneer is immersed in the ligand solution for 5 to 10 minutes.

3. The method for color control of high-performance reconstituted wood according to claim 1, wherein: The adhesive described in step (3) is a phenolic resin adhesive.

4. The method for color control of high-performance reconstituted wood according to claim 1, wherein: The immersion time in step (3) is 10 to 15 minutes.

5. The method for color control of high-performance reconstituted wood according to claim 1, wherein: The drying temperature in step (4) is 60-70°C.

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