High-strength all-wood-based transparent plastic as well as multi-layer self-adhesion forming preparation method and application thereof

Abstract

The invention discloses a high-strength all-wood-based transparent plastic as well as a multi-layer self-adhesion forming preparation method and application of the high-strength all-wood-based transparent plastic. The preparation method comprises the following steps: (1) carrying out delignification treatment on natural wood by using chemical substances; (2) carrying out light-proof oxidation modification treatment on the fully delignified wood obtained in the step (1); (3) the oxidized wood obtained in the step (2) is subjected to normal-temperature reduction modification treatment; and (4) the redox modified wood obtained in the step (3) is placed in a hot press for densification treatment, and the high-strength all-wood-based transparent plastic can be obtained. And (4) or the redox modified wood obtained in the step (3) is vertically overlapped and placed in a hot press to be subjected to lamination densification treatment, the multi-layer self-adhesion all-wood-based transparent plastic is obtained, a good self-adhesion effect can be achieved without adding an adhesive, and enhanced isotropic mechanical strength is presented. The method is simple in process, low in cost and environmentally friendly, the prepared all-wood-based transparent plastic has excellent mechanical strength and optical performance, and the unique room-temperature phosphorescence phenomenon enables the all-wood-based transparent plastic to have great application prospects in the field of intelligent materials.

Description

Technical Field

[0001] The invention relates to the utilization of biomass wood resources, and in particular to a high-strength all-wood-based transparent plastic and a multi-layer self-adhesive molding preparation method and application thereof. Background Art

[0002] As a widely used traditional material, wood has the advantages of high strength, wide sources, and green and renewable. It is widely used in the fields of construction, furniture, structural materials, etc., and has good development prospects under the current green and low-carbon trend. Wood has a unique three-dimensional porous structure and is composed of lignocellulosic biomass represented by cellulose, hemicellulose, and lignin. In recent years, there have been highlights in high-tech fields such as high-strength structural materials and optoelectronic materials. As one of the hot research directions, transparent wood retains the natural microstructure of wood, has excellent mechanical and optical properties, is innovative and green, and is widely used in smart buildings, interior decoration, etc. At present, the main methods for making transparent wood include removing lignin and polymer filling, which have problems such as easy yellowing and poor compatibility between polymer and biomass matrix. In addition, commonly used petroleum-based polymers are difficult to degrade and easily cause environmental pollution, which does not conform to the social trend of green environmental protection. Therefore, it is urgent to develop a simple, green and large-scale production method to construct all-biomass transparent wood-based plastics with excellent mechanical and optical properties.

[0003] The unique anisotropy of wood gives it excellent mechanical strength in the direction of growth, but the weak interaction between fibers in the vertical direction leads to low lateral mechanical strength, which limits the scale development of wood-based materials. Currently, in actual production, adhesives are often applied to achieve the bonding of multiple layers of wood-based materials, but the adhesives commonly used in the market cannot be degraded, pollute the environment, and some are even toxic. Therefore, it is urgent to develop multi-layer wood-based plastics that do not add adhesives and can achieve self-adhesion only through modified wood.

[0004] The present invention relates to a high-strength all-wood-based transparent plastic made of natural wood as raw material and a multi-layer self-adhesive molding preparation method and application thereof. The preparation method has low cost and simple process and is suitable for industrial production. Through a simple top-down process, a high-strength, green and environmentally friendly all-wood-based transparent plastic is obtained without filling polymer. Furthermore, without adding adhesive, a multi-layer self-adhesive transparent wood-based plastic is obtained by in-situ bonding. The unique room temperature phosphorescence property gives the wood-based plastic a wide range of application prospects in the field of smart materials. Summary of the invention

[0005] In view of the deficiencies of the prior art and theory, the present invention proposes a high-strength all-wood-based transparent plastic and a multi-layer self-adhesive molding preparation method and application thereof.

[0006] An object of the present invention is to provide a method for preparing a high-strength all-wood-based transparent plastic, characterized in that it comprises the following steps:

[0007] Step 1: Immerse natural wood in a NaClO2 solution (4-8wt%) with a certain pH value, and perform boiling heating for a period of time to remove a large amount of lignin to achieve wood component regulation.

[0008] Step 2: The fully delignified wood obtained in step 1 is immersed in a sodium periodate solution (1-3 wt%) and heated for a period of time in the dark. After the reaction is completed, the wood is rinsed with pure water to remove residual chemicals to obtain oxidatively modified wood.

[0009] Step 3: using sodium borohydride solution (0.5-1 wt%) to carry out a reduction reaction at room temperature on the oxidized wood obtained in step 2, and then washing away the residual chemical substances with pure water to obtain reduction-modified wood.

[0010] Step 4: Place the redox-modified wood obtained in step 3 into a hot press, and perform hot pressing at a certain temperature and pressure for a period of time to achieve densification treatment, thereby obtaining a fully wood-based transparent plastic.

[0011] Step 4 is to vertically overlap the redox-modified wood obtained in step 3 and place it in a hot press, and perform lamination and densification treatment by hot pressing at a certain temperature and pressure for a period of time, so as to obtain an isotropic multi-layer self-adhesive all-wood-based transparent plastic without adding an adhesive.

[0012] Preferably, the pH value of the NaClO2 solution in step 1 is 4 to 5, and the heating time is 3 to 5 hours.

[0013] Preferably, the heating temperature in step 2 is 60-70° C., and the heating time is 40 to 120 min.

[0014] Preferably, the reaction time in step 3 is 15 to 30 minutes.

[0015] Preferably, in step 4, the densification hot pressing treatment temperature is 50-70° C., the pressure is 5-35 MPa, and the time is 48-60 h.

[0016] The beneficial effects of the present invention are as follows:

[0017] (1) The preparation method includes a simple top-down four-step process, which is convenient to prepare, low in cost, and suitable for industrial production.

[0018] (2) The all-wood-based transparent plastic prepared according to the method of the present invention does not require the addition of petroleum-based polymers, thereby reducing energy loss and being green and environmentally friendly.

[0019] (3) The self-adhesive all-wood-based transparent plastic prepared according to the method of the present invention has isotropic high mechanical strength, breaking the application limitations.

[0020] (4) Unlike traditional multi-layer materials with added adhesives, the multi-layer self-adhesive all-wood-based transparent plastic prepared according to the method of the present invention does not require the addition of adhesives, is low-cost, and is green and safe.

[0021] (5) All-wood-based transparent plastics have high strength, high transparency, high haze, biodegradability, and room temperature phosphorescence. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Flow chart of high-strength all-wood-based transparent plastic prepared by the present invention and its multi-layer self-adhesive molding Figure 2 This is the SEM image of the all-wood-based transparent plastic in Example 2 of the present invention. Figure 3 This is a SEM image of the multi-layer self-adhesive all-wood-based transparent plastic prepared in Example 3 of the present invention.

[0023] Figure 4 The mechanical strength diagram of the all-wood-based transparent plastic prepared in Example 2 of the present invention and the multi-layer self-adhesive all-wood-based transparent plastic prepared in Example 3 is shown in FIG.

[0024] Figure 5 The flexibility display diagram and SEM image of the all-wood-based transparent plastic prepared in Example 2 of the present invention are shown in FIG.

[0025] Figure 6 Figure 2 shows the transparency (left) and haze (right) of the all-wood-based transparent plastic prepared in Example 2 of the present invention and the multi-layer self-adhesive all-wood-based transparent plastic prepared in Example 3.

[0026] Figure 7 Schematic diagram of the recyclability of the all-wood-based transparent plastic prepared in Example 2 of the present invention and the mechanical strength diagram of the recycled sample Figure 8 Application of room temperature phosphorescence of the all-wood-based transparent plastic prepared in Example 2 of the present invention DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the invention more obvious and easy to understand, the specific embodiments of the invention are described in detail below.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0029] Example 1

[0030] (1) Natural balsa wood is immersed in a NaClO2 solution (4-8 wt%) with a certain pH value (4-5) and kept boiling for 3-5 hours to remove lignin, and the residual chemicals are washed away with deionized water.

[0031] (2) using sodium periodate solution (1-3 wt%), 60-70° C. in the dark for 80 min to oxidize and modify the fully delignified wood obtained in step 1. After the reaction, rinse the sample several times with deionized water to remove residual chemicals.

[0032] (3) treating the oxidized modified wood obtained in step 2 with a sodium borohydride solution (0.5-1 wt%) for 15-30 min at room temperature, and then repeatedly washing with deionized water to remove residual chemicals after the reaction.

[0033] (4) The redox-modified wood obtained in step 3 is slightly dried, placed in a hot press, and hot-pressed at 60° C. for 48 h for densification. During the process, the pressure is slowly increased to 35 MPa to obtain a high-strength all-wood-based transparent plastic.

[0034] Example 2

[0035] (1) Same as in Example 1.

[0036] (2) using sodium periodate solution (1-3 wt%), 60-70° C. in the dark for 120 min to oxidize and modify the fully delignified wood obtained in step 1. After the reaction, rinse the sample several times with deionized water to remove residual chemicals.

[0037] (3) Same as in Example 1.

[0038] (4) The redox-modified wood obtained in step 3 is slightly dried, placed in a hot press, and hot-pressed at 60° C. for 60 h for densification. During the process, the pressure is slowly increased to 35 MPa to obtain a high-strength all-wood-based transparent plastic.

[0039] Example 3

[0040] (1) Same as in Example 1.

[0041] (2) Same as in Example 1.

[0042] (3) Same as in Example 1.

[0043] (4) The redox-modified wood obtained in step 3 is slightly dried, two pieces of wood are overlapped vertically (0 / 90°), placed in a hot press, and hot-pressed at 60° C. for 60 h for lamination densification treatment. During the process, the pressure is slowly increased to 35 MPa to obtain an isotropic multi-layer self-adhesive all-wood-based transparent plastic.

[0044] It should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the implementation of the present invention. Those skilled in the art should understand that other different forms of changes can be made based on the above description, and obvious modifications or changes to the technical solution of the present invention should be included in the protection scope of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A high-strength all-wood-based transparent plastic and its multi-layer self-adhesive molding preparation method and application, characterized in that: The steps include: Step 1, immersing natural wood in a NaClO2 solution (4-8 wt%) with a certain pH value, and boiling and heating for a period of time to remove a large amount of lignin to achieve wood component regulation; Step 2, immersing the fully delignified wood obtained in step 1 in a sodium periodate solution (1-3 wt%) and heating for a period of time in the dark, and washing away the residual chemical substances with pure water after the reaction is completed to obtain oxidatively modified wood; Step 3, using a sodium borohydride solution (0.5-1 wt%) to perform a reduction reaction on the oxidized wood obtained in step 2 at room temperature, and then washing away the residual chemical substances with pure water to obtain reduced modified wood; Step 4, placing the redox-modified wood obtained in step 3 into a hot press, and hot pressing for a period of time at a certain temperature and pressure to achieve densification treatment, thereby obtaining a fully wood-based transparent plastic; Step 4 is to vertically overlap the redox-modified wood obtained in step 3 and place it in a hot press, and perform lamination and densification treatment by hot pressing at a certain temperature and pressure for a period of time, so as to obtain an isotropic multi-layer self-adhesive all-wood-based transparent plastic without adding an adhesive.

2. The method according to claim 1, characterized in that The pH value of the NaClO2 solution in step 1 is 4-5, and the heating time is 3-5 hours.

3. The method according to claim 1, characterized in that The heating temperature in step 2 is 60-70° C., and the heating time is 40-120 min.

4. The method according to claim 1, characterized in that The reaction time in step 3 is 15 to 30 minutes.

5. The method according to claim 1, characterized in that In step 4, the densification hot pressing treatment temperature is 50-70° C., the pressure is 5-35 MPa, and the time is 48-60 hours.

6. The method according to claim 1, characterized in that The all-wood-based transparent plastic prepared by this method does not require the addition of polymers, overcomes the problems of traditional transparent wood-based plastics that are prone to yellowing and have poor aging resistance, is green and environmentally friendly, has low cost, simple manufacturing process, and is suitable for industrial production.

7. The method according to claim 1, characterized in that The multi-layer self-adhesive all-wood-based transparent plastic prepared by this method can achieve multi-layer wood self-adhesion without adding adhesives, is safe and environmentally friendly, obtains isotropically enhanced mechanical properties, and has broad application prospects.

8. The room temperature phosphorescent application of the all-wood-based transparent plastic according to claim 1, which is a strong competitor for smart optical materials.

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