Recombinant integrated material with graded gradient structure as well as preparation method and application of recombinant integrated material

Abstract

The invention provides a recombinant integrated material as well as a preparation method and application thereof. The recombined integrated material has a symmetrical different composite structure; the symmetrical different composite structure comprises a central layer, a middle layer and an outer layer, the middle layer is in contact with the outer surface of the central layer, and the outer layer is in contact with the surface, opposite to the central layer, of the middle layer; the central layer comprises a first recombination integration material unit, the middle layer comprises a second recombination integration material unit, and the outer layer comprises a third recombination integration material unit; if the static bending intensity of the first recombination integrated material unit is mu1, the static bending intensity of the second recombination integrated material unit is mu2, and the static bending intensity of the third recombination integrated material unit is mu3, the following relation exists: mu1lt; [mu] 2lt; mu3; if the elastic modulus of the first recombination integrated material unit is mu '1, the elastic modulus of the second recombination integrated material unit is mu' 2, and the elastic modulus of the third recombination integrated material unit is mu '3, the following relations exist: mu' 1lt, mu '2lt and mu' 3.

Description

Technical Field

[0001] The invention relates to a recombinant integrated material with a graded gradient structure and a preparation method and application thereof, and belongs to the application field of biomass materials, in particular to the application field of wood materials and / or bamboo materials. Background Art

[0002] Wood composite materials are the development focus of my country's wood industry, mainly including three types of boards such as fiberboard, particleboard and plywood. As the only renewable and naturally degradable ideal environmental material among the four major materials, wood composite materials are an important green resource that is indispensable for economic construction and people's lives. At present, facing the problems of shortage of wood resources and low performance of materials and products, the huge market demand for high-performance and new ecological wood composite materials can no longer be met. How to use the rich artificial forest resources to develop high-performance and high-value-added wood composite materials on the basis of traditional wood composite materials and expand their new application areas has become a new research hotspot in the field of wood processing.

[0003] As a research hotspot for advanced manufacturing of high-value artificial forest wood and bamboo, recombinant integration technology can overcome the defects of artificial forest wood and bamboo, such as small diameter, soft material, low strength and uneven material. It is also the main method for producing large-scale structural integrated materials of wood composite materials, and can realize the safe application of materials in the field of large-span and high-rise wooden structures. However, a large part of artificial forest and bamboo are currently used in non-structural fields.

[0004] CN116945294A provides a set of steps including processing of non-finger-jointed fir glulam veneers, acquisition of basic data, screening, finger-jointing and lengthening, etc., which can solve the problems of low strength, high discreteness, low yield and high cost of glulam veneers made from some artificial forest fir, and can prepare high-strength and high-modulus finger-jointed fir glulam veneers. However, this method only utilizes the veneers in a graded manner, and does not fundamentally solve the problem of insufficient strength of the material itself.

[0005] CN113211587A is mainly based on compressing and strengthening the surface of the substrate, and performing a stability treatment on the wood by controlling the temperature of the hot pressing plate to obtain the compressed and strengthened wood. The compressed and strengthened wood is then placed in a heat treatment tank, and a secondary stability treatment is performed on the compressed and strengthened wood by controlling the steam or air pressure, temperature and treatment time in the heat treatment tank to obtain a finished product. However, there is a problem that further compression cannot be performed in the later stage, resulting in the inability to accurately control the performance difference, and only the surface is enhanced but the full name of the substrate cannot be composited.

[0006] Therefore, it has become a technical problem to be solved urgently to study a recombinant integrated material with a hierarchical gradient structure and a preparation method thereof to solve the above problems. Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In view of the technical problems existing in the prior art, the present invention first provides a recombinant integrated material with a graded gradient structure. The recombinant integrated material with a graded gradient structure of the present invention has high mechanical strength, so it can be used as a structural material, and can also solve the problems of large mechanical discreteness and poor appearance quality. The recombinant integrated material of the present invention has high utilization rate, large strength-to-weight ratio, good bonding strength of the bonding interface, and good surface flatness.

[0009] Furthermore, the present invention also provides a method for preparing a recombinant integrated material. The preparation method is simple and easy to implement, the raw materials are easy to obtain, and the method is suitable for mass production.

[0010] Solutions for solving problems

[0011] The present invention provides a recombinant integrated material, which has a symmetrical heterogeneous combination structure; the symmetrical heterogeneous combination structure includes a central layer, an intermediate layer and an outer layer, wherein the intermediate layer contacts the outer surface of the central layer, and the outer layer contacts the surface of the intermediate layer opposite to the central layer; wherein:

[0012] The recombinant integrated material includes a recombinant integrated material unit, the central layer includes a first recombinant integrated material unit, the middle layer includes a second recombinant integrated material unit, and the outer layer includes a third recombinant integrated material unit; and

[0013] Assume that the static bending strength of the first reorganized integrated material unit is μ 1 , the static bending strength of the second reorganized integrated material unit is μ 2 , the static bending strength of the third reorganized integrated material unit is μ 3 , then the following relationship exists:

[0014] μ 1 <μ 2 <μ 3 ;

[0015] Assume the elastic modulus of the first recombinant integrated material unit is μ' 1 , the elastic modulus of the second reorganized integrated material unit is μ' 2 , the elastic modulus of the third reorganized integrated material unit is μ' 3 , then the following relationship exists:

[0016] μ' 1 <μ' 2 <μ' 3 .

[0017] According to the recombinant integrated material of the present invention, the static bending strength of the first recombinant integrated material unit is greater than or equal to 30 MPa and less than 50 MPa, and the elastic modulus of the first recombinant integrated material unit is greater than or equal to 5.5 GPa and less than 7.5 GPa;

[0018] The static bending strength of the second recombinant integrated material unit is greater than or equal to 50 MPa and less than 70 MPa, and the elastic modulus of the first recombinant integrated material unit is greater than or equal to 7.5 GPa and less than 9.5 GPa;

[0019] The static bending strength of the third recombinant integrated material unit is greater than or equal to 70 MPa, and the elastic modulus of the third recombinant integrated material unit is greater than or equal to 9.5 Gpa.

[0020] According to the recombinant integrated material of the present invention, the recombinant integrated material unit is derived from biomass material; preferably, the biomass material includes bamboo material and / or wood material; and / or the thickness of the recombinant integrated material unit is 5-40 mm.

[0021] According to the recombinant integrated material of the present invention, wherein the recombinant integrated material unit is obtained through enhanced shaping treatment; and / or,

[0022] The symmetrical isotropic combination structure is formed by using an adhesive; preferably, the adhesive includes one or a combination of two or more of soybean glue, isocyanate adhesive, phenolic resin adhesive, polyurethane adhesive, and latex glue.

[0023] The present invention also provides a method for preparing the recombinant integrated material according to the present invention, which comprises the steps of composite-molding the central layer, the middle layer and the outer layer in a symmetrical and heterogeneous assembly manner.

[0024] The preparation method according to the present invention comprises the following steps:

[0025] The recombinant material unit is recombined by enhanced shaping treatment to obtain a recombinant integrated material unit;

[0026] Using a stress grading machine to dynamically measure and obtain the elastic modulus and static bending strength of the recombinant integrated material unit;

[0027] According to the static bending strength and the elastic modulus, the recombinant integrated material unit is divided into a first recombinant integrated material unit, a second recombinant integrated material unit and a third recombinant integrated material unit;

[0028] After introducing adhesive into the first recombinant integrated material unit, the second recombinant integrated material unit and the third recombinant integrated material unit, a symmetrical and heterogeneous assembly method is adopted to assemble the blanks, and the center layer, the middle layer and the outer layer are composite-molded to form a composite blank;

[0029] The composite blank is subjected to cold pressing and / or hot pressing to obtain the recombinant integrated material.

[0030] According to the preparation method of the present invention, the enhanced shaping includes the step of applying constant pressure while heating; preferably, the temperature of the enhanced shaping treatment is 150-200°C, the enhanced shaping treatment time is 20-65min, and the constant pressure is 0.5-5.5MPa.

[0031] According to the preparation method of the present invention, the amount of the adhesive applied is 150-300 g / m 2 .

[0032] According to the preparation method of the present invention, the temperature of the hot pressing is 100-170°C, and the pressure of the hot pressing is 8-20kg / cm 2 , the heat pressing time is 0.5-3min / mm; and / or,

[0033] The cold pressing temperature is 10-40°C, and the cold pressing pressure is 10-20kg / cm 2 The cold pressing time is 60-180min.

[0034] The present invention also provides a use of the recombinant integrated material according to the present invention in load-bearing and / or house construction.

[0035] Effects of the Invention

[0036] The recombinant integrated material of the graded gradient structure of the present invention has high mechanical strength and excellent appearance quality, and can be used as a structural material. The recombinant integrated material of the present invention has high utilization rate, large strength-to-weight ratio, excellent bonding interface adhesion and surface flatness.

[0037] The preparation method of the recombinant integrated material of the present invention is simple and easy, the raw materials are easy to obtain, and it is suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram showing the preparation process of the recombinant integrated material with a graded gradient structure;

[0039] Figure 2 A schematic diagram of the vertical cross-sectional density of the recombinant integrated material unit is shown;

[0040] Figure 3 The distribution of bending properties of veneers with different thicknesses at each level is shown.

[0041] Figure 4 A schematic diagram showing the comparison of the glue distribution of the glue-reinforced recombinant integrated material unit and the traditional glue coating is shown;

[0042] Figure 5 A schematic diagram of hierarchical reorganization of integrated material unit assemblies is shown. DETAILED DESCRIPTION

[0043] Various exemplary embodiments, features and aspects of the present invention will be described in detail below. The word "exemplary" used here means "used as an example, embodiment or illustrative". Any embodiment described here as "exemplary" is not necessarily interpreted as being superior or better than other embodiments.

[0044] In addition, in order to better illustrate the present invention, numerous specific details are provided in the following specific embodiments. It should be understood by those skilled in the art that the present invention can be implemented without certain specific details. In other examples, methods, means, equipment and steps well known to those skilled in the art are not described in detail in order to highlight the subject matter of the present invention.

[0045] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0046] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0047] In this specification, the references to "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", etc., mean that the specific elements (e.g., features, structures, properties and / or characteristics) described in connection with the embodiments are included in at least one embodiment described herein, and may or may not exist in other embodiments. In addition, it should be understood that the elements may be combined in various embodiments in any suitable manner.

[0048] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0049] <First aspect>

[0050] like Figure 5 As shown, the first aspect of the present invention provides a recombinant integrated material, which has a symmetrical heterogeneous combination structure; the symmetrical heterogeneous combination structure includes a central layer, an intermediate layer and an outer layer, the intermediate layer is in contact with the outer surface of the central layer, and the outer layer is in contact with the surface of the intermediate layer opposite to the central layer; wherein,

[0051] The recombinant integrated material includes a recombinant integrated material unit, the central layer includes a first recombinant integrated material unit, the middle layer includes a second recombinant integrated material unit, and the outer layer includes a third recombinant integrated material unit; and

[0052] Assume that the static bending strength of the first reorganized integrated material unit is μ 1 , the static bending strength of the second reorganized integrated material unit is μ 2 , the static bending strength of the third reorganized integrated material unit is μ 3 , then the following relationship exists:

[0053] μ 1 <μ 2 <μ 3 ;

[0054] Assume the elastic modulus of the first recombinant integrated material unit is μ' 1 , the elastic modulus of the second reorganized integrated material unit is μ' 2 , the elastic modulus of the third reorganized integrated material unit is μ' 3 , then the following relationship exists:

[0055] μ' 1 <μ' 2 <μ' 3 .

[0056] The recombinant integrated material of the graded gradient structure of the present invention has high mechanical strength and excellent appearance quality, so it can be used as a structural material with high utilization rate, large strength-to-weight ratio, good bonding strength at the bonding interface, and good surface flatness. The central layer includes a first recombinant integrated material unit, which can effectively ensure that the graded gradient structure recombinant integrated material can more effectively resist external forces when subjected to bending stress. At the same time, the layered structure can effectively disperse stress and prevent a certain layer of recombinant integrated material units from being subjected to excessive stress alone, thereby improving the stability of the overall structure. This structural design is commonly used in lightweight, high-performance structural optimization methods in the aerospace, construction, and automotive industries.

[0057] In the present invention, the symmetrical heterogeneous composite structure means that the recombinant integrated material comprises an outer layer, an intermediate layer, a central layer, a central layer, an intermediate layer and an outer layer in sequence, and a symmetrical structure is formed on both sides with the central layer and the space between the central layers as the center.

[0058] In some specific embodiments, the recombinant integrated material unit is derived from biomass materials; preferably, the biomass materials include bamboo materials and / or wood materials. The wood materials and / or bamboo materials of the present invention can be made from wood peeling veneers and / or bamboo flattened veneers. Specifically, the peeling wood veneer can be made from fast-growing forest wood as raw material, such as: poplar, fir, radiata pine, eucalyptus, larch, Douglas fir, Cryptomeria japonica, metasequoia or spruce. The flattened bamboo veneer is made from bamboo as raw material, such as: moso bamboo, ma bamboo, dragon bamboo or giant dragon bamboo, and specifically, the thickness of the recombinant integrated material unit of the present invention can be 5-40mm, such as: 7mm, 8mm, 9mm, 10mm, 12mm, 15mm, 20mm, 25mm, 30mm, 35mm, etc.

[0059] In some specific embodiments, the static bending strength of the first recombinant integrated material unit is greater than or equal to 30MPa and less than 50MPa, and the elastic modulus of the first recombinant integrated material unit is greater than or equal to 5.5GPa and less than 7.5Gpa; the static bending strength of the second recombinant integrated material unit is greater than or equal to 50MPa and less than 70MPa, and the elastic modulus of the second recombinant integrated material unit is greater than or equal to 7.5GPa and less than 9.5Gpa; the static bending strength of the third recombinant integrated material unit is greater than or equal to 70MPa, and the elastic modulus of the third recombinant integrated material unit is greater than or equal to 9.5Gpa. When the elastic modulus and static bending strength of the first recombinant integrated material unit, the second recombinant integrated material unit, and the third recombinant integrated material unit are within the above range, the overall bending strength of the recombinant integrated material is effectively guaranteed, so that it can be used as a structural material.

[0060] In some specific embodiments, the recombinant integrated material unit is obtained through enhanced shaping treatment. The inventors of the present invention have found that the enhanced shaping treatment can increase the surface density and increase the density difference between the surface layer and the core layer, forming a steep vertical profile density distribution between the surface layer and the core layer, thereby improving the strength of the board. Specifically, the enhanced shaping treatment can be a step of applying a constant pressure while heating.

[0061] In some specific embodiments, the symmetrical isomeric combination structure is formed by using an adhesive; preferably, the adhesive includes one or a combination of two or more of soybean glue, isocyanate adhesive, phenolic resin adhesive, polyurethane adhesive, and latex glue.

[0062] <Second Aspect>

[0063] The second aspect of the present invention provides a method for preparing the recombinant integrated material according to the first aspect of the present invention, which comprises the steps of composite molding a central layer, an intermediate layer and an outer layer in a symmetrical and heterogeneous assembly manner.

[0064] The preparation method of the invention is simple and easy to implement, the raw materials are easy to obtain, and it is suitable for mass production.

[0065] In some specific embodiments, the steps include:

[0066] The recombinant material unit is recombined by enhanced shaping treatment to obtain a recombinant integrated material unit;

[0067] Using a stress grading machine to dynamically measure and obtain the elastic modulus and static bending strength of the recombinant integrated material unit;

[0068] According to the static bending strength and the elastic modulus, the recombinant integrated material unit is divided into a first recombinant integrated material unit, a second recombinant integrated material unit and a third recombinant integrated material unit;

[0069] After introducing adhesive into the first recombinant integrated material unit, the second recombinant integrated material unit and the third recombinant integrated material unit, a symmetrical and heterogeneous assembly method is adopted to assemble the blanks, and the center layer, the middle layer and the outer layer are composite-molded to form a composite blank;

[0070] The composite blank is subjected to cold pressing and / or hot pressing to obtain the recombinant integrated material.

[0071] The present invention obtains a reorganized integrated material unit by strengthening shaping treatment to reorganize the material unit. The inventor of the present invention has found that the surface density can be increased by strengthening shaping treatment to increase the density difference between the surface layer and the core layer, forming a steep vertical profile density distribution of the surface layer and the core layer, thereby improving the strength of the board. Specifically, the strengthening shaping treatment can be a step of applying constant pressure while heating. Specifically, the wood material and / or bamboo material can be sent to a hot press for pressurized heating and densification.

[0072] In some specific embodiments, the temperature of the enhanced shaping treatment is 150-200°C, for example: 160°C, 170°C, 180°C, 190°C, etc.; the time of the enhanced shaping treatment is 10-65min, for example: 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min, 55min; the constant pressure is 0.5-5.5MPa, for example: 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4.5MPa, etc.

[0073] In the present invention, the elastic modulus and static bending strength of the recombinant integrated material unit are obtained by dynamic measurement using a stress grading machine; the elastic modulus and static bending strength of the recombinant integrated material unit are measured, and their ranges can be graded to screen out the recombinant integrated material units with the required elastic modulus and static bending strength. Then, according to the size of the static bending strength and the elastic modulus, the recombinant integrated material unit is divided into a first recombinant integrated material unit, a second recombinant integrated material unit and a third recombinant integrated material unit;

[0074] Furthermore, after the adhesive is introduced into the first recombinant integrated material unit, the second recombinant integrated material unit and the third recombinant integrated material unit, a symmetrical and heterogeneous assembly method is adopted to assemble the blanks, and the central layer, the middle layer and the outer layer are compositely molded to form a composite blank.

[0075] In some specific embodiments, the adhesive can be introduced by roller dipping and coating. Specifically, the roller dipping and coating can use diamond rolling roller teeth to introduce the adhesive. The diamond rolling used in the present invention can give full play to the role of glue nails at the macroscopic bonding interface on the surface, and at the same time use rolling to form a new penetration channel for the adhesive, and use negative pressure to achieve microscopic penetration and wrapping of the adhesive on the recombinant integrated material unit, thereby enhancing the performance of the bonding interface and forming a bonding-enhanced recombinant integrated material unit.

[0076] Specifically, the present invention can set the roller gap to 1-5 mm, and apply glue to the reinforced shaped eucalyptus veneer through the roller at a line speed of 5-10 mm / min, and the number of roller gluing is 1-5 times.

[0077] Specifically, the amount of adhesive applied is 150-300 g / m 2 The amount of the adhesive of the present invention can be 160g / m 2 , 180g / m 2 , 200g / m 2 , 220g / m 2 , 240g / m 2 , 260g / m 2 , 280g / m 2 wait.

[0078] Afterwards, a symmetrical and heterogeneous assembly method is used to assemble the blanks, and the center layer, the middle layer, and the outer layer are compositely molded to form a composite blank. Specifically, the composite blank is formed by a symmetrical and heterogeneous assembly method of the center layer, the middle layer, and the outer layer. The present invention does not specifically limit the assembly method, and preferably adopts a method of assembling the blanks along the grain.

[0079] Furthermore, the composite blank is subjected to cold pressing and / or hot pressing to obtain the recombinant integrated material.

[0080] Specifically, in the hot pressing treatment, the hot pressing temperature is 100-170°C, for example: 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, etc.; the hot pressing pressure is 8-20kg / cm 2 , for example: 10kg / cm 2 , 12kg / cm 2 、14kg / cm 2 , 16kg / cm 2 、18kg / cm 2 etc.; the hot pressing time is 0.5-3min / mm, for example, 1min / mm, 1.2min / mm, 1.5min / mm, 1.8min / mm, 2min / mm, 2.2min / mm, 2.5min / mm, 2.8min / mm, etc.

[0081] In the cold pressing process, the cold pressing temperature is 10-40°C, for example: 15°C, 20°C, 25°C, 30°C, 35°C, etc.; the cold pressing pressure is 10-20kg / cm 2 , for example: 12kg / cm 2 、14kg / cm 2 , 16kg / cm 2 、18kg / cm 2 etc.; the cold pressing time is 60-180min, for example: 80min, 100min, 120min, 140min, 160min, etc.

[0082] <Third Aspect>

[0083] The third aspect of the present invention provides a use of the recombinant integrated material according to the first aspect of the present invention in load-bearing and / or house construction.

[0084] In the present invention, the bending strength of the recombinant integrated material with graded gradient structure of the present invention meets the requirements of GB / T 26899-2022 "Structural Integrated Materials" E 14 Mechanical grading layer requirements, can be used to manufacture symmetrical heterogeneous TC YD 40 and equivalent TC T Glulam of strength grade 40.

[0085] The recombinant integrated material of the present invention has high mechanical strength and excellent appearance quality, and can be used for load bearing and house construction.

[0086] Example

[0087] The embodiments of the present invention will be described in detail below in conjunction with the examples, but those skilled in the art will appreciate that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. If no specific conditions are specified in the examples, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0088] Example 1

[0089] like Figure 1 As shown, 10 mm bamboo flattened veneer is used as raw material, and a hot press is used to pressurize and heat the bamboo flattened veneer for enhanced shaping. The enhanced shaping treatment temperature is 150°C, the constant pressure is 4.5 MPa, and the treatment time is 20 minutes to obtain an enhanced and shaped bamboo flattened veneer.

[0090] Then, the elastic modulus and static bending strength of each reinforced shaped bamboo flattened veneer are directly and dynamically measured through a stress grading machine. And further, three mechanical stress levels, namely, level I, level II and level III, are used to establish a stress grading criterion. Among them, level I corresponds to a reinforced shaped bamboo flattened veneer with a static bending strength greater than or equal to 70MPa and an elastic modulus greater than or equal to 9.5GPa; level II corresponds to a reinforced shaped bamboo flattened veneer with a static bending strength greater than or equal to 50MPa and less than 70MPa, and an elastic modulus greater than or equal to 7.5GPa and less than 9.5GPa; level III corresponds to a reinforced shaped bamboo flattened veneer with a static bending strength greater than or equal to 30MPa and less than 50MPa, and an elastic modulus greater than or equal to 5.5GPa and less than 7.5GPa.

[0091] The diamond-shaped rolling roller teeth are used to introduce adhesive into the recombinant integrated material unit, and the roller gap is set to 2mm. The reinforced shaped eucalyptus veneer is glued through the roller at a line speed of 7.32mm / min, and the number of roller gluing is 3 times. The adhesive is polyurethane adhesive, and the amount of the adhesive is 180g / m 2 Then, two layers of the center layer (mechanical stress level III), the middle layer (mechanical stress level II) and the outer layer (mechanical stress level I) are symmetrically assembled to form a composite blank, and the assembly method is the same as the grain assembly method. In the composite blank, there are a total of six layers of reinforced shaped bamboo flattened veneer.

[0092] Finally, the composite blank is subjected to cold pressing to form a reconstructed integrated material. The cold pressing temperature is 30°C and the cold pressing pressure is 10kg / cm 2 The cold pressing time is 180 minutes, so that the finished recombinant integrated material with a graded gradient structure can be obtained.

[0093] Example 2

[0094] like Figure 1 As shown, a 10 mm poplar veneer is used as a raw material, and a hot press is used to pressurize and heat the poplar veneer for enhanced shaping. The temperature of the enhanced shaping treatment is 150°C, the constant pressure is 4.5 MPa, and the treatment time is 20 minutes to obtain an enhanced and shaped poplar veneer.

[0095] Then, the elastic modulus and static bending strength of each reinforced shaped poplar veneer are directly and dynamically measured through a stress grading machine. And further, three mechanical stress levels, namely, level I, level II and level III, are used to establish stress grading criteria. Among them, level I corresponds to reinforced shaped poplar veneers with static bending strength greater than or equal to 70MPa and elastic modulus greater than or equal to 9.5GPa; level II corresponds to reinforced shaped poplar veneers with static bending strength greater than or equal to 50MPa and less than 70MPa, elastic modulus greater than or equal to 7.5GPa and less than 9.5GPa; level III corresponds to reinforced shaped poplar veneers with static bending strength greater than or equal to 30MPa and less than 50MPa, elastic modulus greater than or equal to 5.5GPa and less than 7.5GPa.

[0096] The diamond-shaped rolling roller teeth are used to introduce adhesive into the recombinant integrated material unit, and the roller gap is set to 2mm. The reinforced shaped eucalyptus veneer is glued through the roller at a line speed of 7.32mm / min, and the number of roller gluing is 3 times. The adhesive is polyurethane adhesive, and the amount of the adhesive is 180g / m 2 Then, two layers of the center layer (mechanical stress level III), the middle layer (mechanical stress level II), and the outer layer (mechanical stress level I) are symmetrically assembled to form a composite blank, and the assembly method is the parallel grain assembly method. In the composite blank, there are a total of six layers of reinforced shaped poplar veneer.

[0097] Finally, the composite blank is subjected to cold pressing to form a reconstructed integrated material. The cold pressing temperature is 30°C and the cold pressing pressure is 10kg / cm 2 The cold pressing time is 180 minutes, so that a finished recombinant integrated material with a graded gradient structure can be obtained.

[0098] Example 3

[0099] 7mm eucalyptus peeled veneer was used as raw material, and the eucalyptus peeled veneer was pressurized and heated by a hot press to perform enhanced shaping treatment. The enhanced shaping treatment temperature was 150°C, the constant pressure was 3Mpa, and the treatment time was 15 minutes to obtain enhanced shaped eucalyptus veneer.

[0100] Then, the elastic modulus and static bending strength of each enhanced shaped eucalyptus veneer are directly and dynamically measured through the stress grading machine, and the stress grading criteria are further established using three mechanical stress levels, namely, level I, level II and level III. Among them, level I corresponds to enhanced shaped poplar veneers with a static bending strength greater than or equal to 70MPa and an elastic modulus greater than or equal to 9.5GPa; level II corresponds to enhanced shaped poplar veneers with a static bending strength greater than or equal to 50MPa and less than 70MPa, and an elastic modulus greater than or equal to 7.5GPa and less than 9.5GPa; level III corresponds to enhanced shaped eucalyptus veneers with a static bending strength greater than or equal to 30MPa and less than 50MPa, and an elastic modulus greater than or equal to 5.5GPa and less than 7.5GPa.

[0101] The diamond-shaped rolling roller teeth are used to introduce adhesive into the recombinant integrated material unit, and the roller gap is set to 2mm. The reinforced shaped eucalyptus veneer is glued through the roller at a line speed of 7.32mm / min. The number of roller gluing is 3 times. The adhesive is polyurethane adhesive, and the amount of the adhesive is 220g / m 2 Then, two layers of the center layer (mechanical stress level III), the middle layer (mechanical stress level II), and the outer layer (mechanical stress level I) are symmetrically assembled to form a composite blank, and the assembly method is the parallel grain assembly method. In the composite blank, six layers of reinforced shaped eucalyptus veneer are used.

[0102] Finally, the composite blank is subjected to cold pressing to form a reconstructed integrated material. The cold pressing temperature is 30°C and the cold pressing pressure is 10kg / cm 2 The cold pressing time is 180 minutes, so that a finished recombinant integrated material with a graded gradient structure can be obtained.

[0103] Comparative Example 1

[0104] 10mm flattened bamboo veneer was used as raw material, and diamond-shaped rolling roller teeth were used to introduce adhesive. The roller gap was set to 2mm, and the reinforced shaped eucalyptus veneer was glued through the roller at a line speed of 7.32mm / min, and the number of roller gluing was 3 times. The adhesive was polyurethane adhesive, and the amount of the adhesive was 180g / m 2 Then the blanks are assembled in the same way as the grain to form a composite blank. The composite blank is then cold pressed to form a recombinant integrated material. The cold pressing temperature is 30°C and the cold pressing pressure is 10kg / cm 2 The cold pressing time is 180 minutes, so that the recombinant integrated material can be obtained.

[0105] Comparative Example 2

[0106] 8mm poplar flattened veneer is used as raw material, and diamond-shaped rolling roller teeth are used to introduce adhesive. The roller gap is set to 2mm, and the reinforced shaped eucalyptus veneer is glued through the roller at a line speed of 7.32mm / min. The number of roller gluing is 3 times. The adhesive is polyurethane adhesive, and the amount of the adhesive is 180g / m 2 Then the blanks are assembled in the same way as the grain to form a composite blank. The composite blank is then cold pressed to form a recombinant integrated material. The cold pressing temperature is 30°C and the cold pressing pressure is 10kg / cm 2 The cold pressing time is 180 minutes, so that the recombinant integrated material can be obtained.

[0107] Performance Testing

[0108] 1. Profile density test

[0109] A profile density scanner (GreCon DAX6000) was used to detect the vertical profile density of the reconstructed integrated material unit of the reinforced and shaped bamboo flattened veneer and the flattened bamboo veneer without enhanced and shaped treatment. The size of the tested specimen was 50mm×50mm×20mm. The results are as follows Figure 2 shown.

[0110] Depend on Figure 2 It can be seen that after the enhanced shaping treatment, the density distribution of the veneer at the end face is transformed from the traditional density distribution to the steep density distribution compared to the original end face, which can effectively increase the bending strength of the veneer.

[0111] 2. Classification test conditions According to the national standard GB / T 17657-2013 "Test methods for physical and chemical properties of artificial boards and veneer artificial boards", the recombinant integrated material unit prepared in Example 2 was tested for its bending performance. The static bending strength is the ratio of the bending moment and the bending section modulus of the specimen under the maximum load. This test mainly tests the static bending strength of three-point bending, which is measured by applying a load to the middle of the specimen supported at two points. The results are as follows: Figure 3 shown.

[0112] Depend on Figure 3 It can be seen that the bending properties of different recombinant integrated material units are normally distributed. The average static bending strength of grade I, grade II and grade III reinforced shaped poplar veneers are 90.61MPa, 62.14MPa and 42.09MPa, respectively, and the elastic modulus is 10.79GPa, 8.18GPa and 7.24GPa, respectively. Grade I reinforced shaped poplar veneer has the highest bending performance, followed by grade II, and grade III has the lowest.

[0113] 3. Characterization of glue distribution performance of adhesive-reinforced recombinant integrated materials

[0114] The distribution of the glue in the bonding reinforced recombinant integrated material unit of Example 1 and Comparative Example 1 was measured by scanning electron microscopy, laser confocal microscopy, energy dispersive spectrometer and transmission electron microscopy (SEM, S-4800, Hitachi, Japan; EVO18, Zeiss, Germany). The results are as follows: Figure 4 shown.

[0115] Depend on Figure 4 It can be seen that in comparative example 1, the adhesive is mainly distributed in the thin-walled cell cavity and on the inner wall of the duct. This is because in the normal pressure glue coating method, the adhesive is mainly attached to the unit surface by free diffusion, and part of the adhesive will enter the fiber bundle with the microscopic form. The problem of uneven dipping is prone to occur. In Example 1, when passing through the gap between the rollers during the roller pressing and impregnation process, the prismatic teeth on the rollers partially damage the surface of the veneer, and the adhesive can penetrate into the unit through the damaged parts caused by the roller pressing, and at the same time, glue nails are formed at the bonding interface.

[0116] By observing the distribution of resin in recombinant bamboo by CLSM and TEM, it can be seen that in Comparative Example 1, the resin is mainly distributed in the bonding interface, and less glue penetrates into nearby cells. However, in Example 1, under the action of roller pressure, the resin will penetrate into the vicinity of the bonding interface along with the crack adsorption process of the thin-walled cell wall, and glue nails will also be formed in the cell wall and pits at the microscopic level. In addition, since the rolling damages the cell wall of the thin-walled cells, the adhesive can easily penetrate the thin-walled cells and enter the cell corners and adjacent thin-walled cell cavities.

[0117] 4. Water absorption thickness expansion rate and mechanical properties testing

[0118] The finished products prepared in Examples 1-3 and Comparative Examples 1-2 were tested for water absorption thickness expansion rate, bending strength and shear strength. The water absorption thickness expansion rate and bending strength tests of the recombinant integrated material were carried out in accordance with the method specified in the national standard "GB / T 17657-2013 Test Methods for Physical and Chemical Properties of Artificial Boards and Facing Artificial Boards". The water absorption thickness expansion rate test was conducted by placing a sample of 50 mm × 50 mm × 10 mm in a constant temperature water bath with a pH value of 7 ± 1 and a temperature of (63 ± 3) ° C and soaking it for 24 hours.

[0119] The bending strength test is carried out in accordance with GBT 26899-2022 Structural Glulam, which uses a universal testing machine to test the static bending strength and elastic modulus in three-point bending mode. The sample size is 240mm×20mm×10mm. During the test, the load stress at the two loading points is equal, the loading is uniform, and the loading speed is 14.7MPa / min.

[0120] The shear strength test was conducted in accordance with the national standard GB / T 20241-2006 Single-layer substrate. The specimen size was 63mm×40mm×10mm, and the loading speed was 5mm / min, ensuring that the specimen was destroyed within 3 minutes.

[0121] Table 2 Performance indicators of recombinant materials

[0122]

[0123] From the above data, it can be concluded that the water absorption thickness expansion rate of the recombinant integrated materials of Examples 1-3 of the present invention is lower than that of Comparative Examples 1-2. The larger the expansion rate, the more likely the surface will bulge or even fall off, seriously affecting the service life. Therefore, the deformation degree of the recombinant integrated materials prepared by the present preparation method is greatly improved after water absorption. In addition, the shear strength and bending properties of Examples 1-3 are greatly improved, which is mainly attributed to the symmetrical heterogeneous tissue structures with different stress levels and the enhanced effect of the interaction of the prismatic glue nails formed during the rolling process. In addition, the strength grades of foreign imported glued wood used in the glued wood structures built in my country, such as the Chengdu Tianfu Agricultural Expo Park and the Taiyuan Botanical Garden Exhibition Hall, are not greater than TC YD 40 or TC T 40. In summary, the strength performance index of the recombinant integrated material with graded gradient structure of the present invention has reached the world's advanced level.

[0124] It should be noted that, although the technical solution of the present invention is introduced with specific examples, those skilled in the art will appreciate that the present invention should not be limited thereto.

[0125] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A recombinant integrated material, characterized in that: The recombinant integrated material has a symmetrical heterogeneous combination structure; the symmetrical heterogeneous combination structure includes a central layer, an intermediate layer and an outer layer, the intermediate layer is in contact with the outer surface of the central layer, and the outer layer is in contact with the surface of the intermediate layer opposite to the central layer; wherein, The recombinant integrated material includes a recombinant integrated material unit, the central layer includes a first recombinant integrated material unit, the middle layer includes a second recombinant integrated material unit, and the outer layer includes a third recombinant integrated material unit; and Assuming that the static bending strength of the first reorganized integrated material unit is μ1, the static bending strength of the second reorganized integrated material unit is μ2, and the static bending strength of the third reorganized integrated material unit is μ3, the following relationship exists: μ1<μ2<μ3; Assuming the elastic modulus of the first reorganized integrated material unit is μ'1, the elastic modulus of the second reorganized integrated material unit is μ'2, and the elastic modulus of the third reorganized integrated material unit is μ'3, the following relationship exists: μ'1<μ'2<μ'3.

2. The recombinant integrated material according to claim 1, characterized in that: The static bending strength of the first recombinant integrated material unit is greater than or equal to 30 MPa and less than 50 MPa, and the elastic modulus of the first recombinant integrated material unit is greater than or equal to 5.5 GPa and less than 7.5 GPa; The static bending strength of the second recombinant integrated material unit is greater than or equal to 50 MPa and less than 70 MPa, and the elastic modulus of the first recombinant integrated material unit is greater than or equal to 7.5 GPa and less than 9.5 GPa; The static bending strength of the third recombinant integrated material unit is greater than or equal to 70 MPa, and the elastic modulus of the third recombinant integrated material unit is greater than or equal to 9.5 Gpa.

3. The recombinant integrated material according to claim 1 or 2, characterized in that: The recombinant integrated material unit is derived from biomass material; preferably, the biomass material includes bamboo material and / or wood material; and / or the thickness of the recombinant integrated material unit is 5-40 mm.

4. The recombinant integrated material according to any one of claims 1 to 3, characterized in that: The recombinant integrated material unit is obtained through enhanced shaping treatment; and / or, The symmetrical isotropic combination structure is formed by using an adhesive; preferably, the adhesive includes one or a combination of two or more of soybean glue, isocyanate adhesive, phenolic resin adhesive, polyurethane adhesive, and latex glue.

5. A method for preparing a recombinant integrated material according to any one of claims 1 to 4, characterized in that: The method comprises the steps of compositely molding a center layer, a middle layer and an outer layer by adopting a symmetrical and heterogeneous assembly method.

6. The preparation method according to claim 5, characterized in that: The following steps are involved: The recombinant material unit is recombined by enhanced shaping treatment to obtain a recombinant integrated material unit; Using a stress grading machine to dynamically measure and obtain the elastic modulus and static bending strength of the recombinant integrated material unit; According to the static bending strength and the elastic modulus, the recombinant integrated material unit is divided into a first recombinant integrated material unit, a second recombinant integrated material unit and a third recombinant integrated material unit; After introducing adhesive into the first recombinant integrated material unit, the second recombinant integrated material unit and the third recombinant integrated material unit, a symmetrical and heterogeneous assembly method is adopted to assemble the blanks, and the center layer, the middle layer and the outer layer are composite-molded to form a composite blank; The composite blank is subjected to cold pressing and / or hot pressing to obtain the recombinant integrated material.

7. The preparation method according to claim 6, characterized in that: The enhanced shaping includes the step of applying a constant pressure while heating; preferably, the temperature of the enhanced shaping treatment is 150-200° C., the time of the enhanced shaping treatment is 20-65 min, and the constant pressure is 0.5-5.5 MPa.

8. The preparation method according to claim 6 or 7, characterized in that: The amount of adhesive applied is 150-300g / m 2 .

9. The preparation method according to any one of claims 6 to 8, characterized in that: The temperature of the hot pressing is 100-170°C, and the pressure of the hot pressing is 8-20kg / cm 2 , the heat pressing time is 0.5-3min / mm; and / or, The cold pressing temperature is 10-40°C, and the cold pressing pressure is 10-20kg / cm 2 The cold pressing time is 60-180min.

10. Use of the recombinant integrated material according to any one of claims 1 to 4 in load-bearing and / or building construction.

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