High-performance mineral-based adhesive for recycling of bulk solid waste and preparation method thereof

Abstract

The application discloses a high-performance mineral-based adhesive for recycling of bulk solid waste and a preparation method thereof. The high-performance mineral-based adhesive for recycling of bulk solid waste comprises raw materials in the following proportions by weight: 100 parts of active mineral, 1-100 parts of solid alkali activator, 1-200 parts of distilled water, 1-200 parts of epoxy resin and 0-30 parts of silane coupling agent. The application also provides a wood-based panel prepared from the adhesive. The wood-based panel is prepared by the following steps: ball milling and pre-reaction of raw materials, preparation of the mineral-based adhesive, coating of the adhesive on a single board to form a board blank, hot pressing, and post-processing. The wet bonding strength of the product reaches 1.31 MPa, meeting the strength requirement of GB / T 9846-2015 "General plywood" for type II plywood, and the product does not release formaldehyde. The solid alkali activator is used to replace the traditional alkali activation liquid mode, and the prepared adhesive has the advantages of easy control of solid content, convenient transportation, simple process, low cost and the like, and the wood-based panel prepared from the adhesive has the advantages of high performance and good water resistance.

Description

Technical Field

[0001] This invention relates to a mineral adhesive system, specifically to an adhesive system for preparing plywood, plywood prepared using the system, and a method thereof. Background Technology

[0002] In recent years, socio-economic growth and improved living standards have led to a significant increase in demand for wood products. Promoting a comprehensive green transformation of the wood processing industry and encouraging the development, application, and promotion of new environmentally friendly adhesives will be the future direction of the wood industry. Currently widely used traditional wood adhesives such as urea-formaldehyde resin, phenol-formaldehyde resin, and melamine-formaldehyde heavily rely on limited petrochemical resources, which does not meet the national requirements for the industry's future green, low-carbon, environmentally friendly, and sustainable development, and is detrimental to the further development of the engineered wood products industry. Therefore, utilizing sustainable materials to manufacture new wood adhesives has become a key issue that the engineered wood products industry urgently needs to address. As a large-scale solid waste with high emissions, fly ash, metakaolin, and other active minerals have the characteristics of large reserves, sustainability, and low carbon sequestration. Affected by factors such as resource endowment, energy structure, and development stage, my country's large-scale solid waste will still face the severe challenges of high generation intensity, insufficient utilization, and low added value of comprehensive utilization products in the future. Research shows that active minerals show great potential as inorganic cementing materials. Preparing them into mineral polymers through alkali activation can provide an alternative for the preparation of green, harmless, low-carbon, environmentally friendly, and sustainable wood adhesives. However, existing mineral polymer adhesives have unsatisfactory overall performance, especially in terms of bonding strength, which fails to meet the strength requirements for Class II plywood in GB / T 9846-2015 "Ordinary Plywood". This invention proposes an effective and high-strength mineral adhesive and its preparation method. This method provides a green approach for the recycling and reuse of bulk solid waste and offers a novel high-performance mineral adhesive for the wood industry, with significant economic and ecological benefits. Summary of the Invention

[0003] This invention addresses the shortcomings of existing technologies by providing a high-performance mineral adhesive for the reuse of bulk solid waste and its preparation method. This invention uses a solid alkali activator instead of the traditional alkali activating liquid method, resulting in an adhesive with advantages such as easy control of solid content, convenient transportation, and simple processing. By introducing epoxy resin, the mineral adhesive and epoxy resin form an organic-inorganic double cross-linked network with a shell-like "brick-and-mortar" structure during the bonding and curing process, resulting in a denser matrix structure and improved bonding strength. Furthermore, the introduction of a silane coupling agent promotes the formation of a gradient structure at the interface between the mineral adhesive and wood, enhancing the adhesive's cohesion and adhesion to the wood surface, thereby improving the adhesive's strength and water resistance.

[0004] To achieve the objectives of this invention, one aspect of this invention provides a high-performance mineral adhesive for the reuse of bulk solid waste, a method for preparing the same, and plywood prepared using the same. The technical solution adopted is as follows:

[0005] A high-performance mineral adhesive for the recycling of bulk solid waste, its preparation method, and plywood prepared using the same, comprising the following steps:

[0006] The adhesive is prepared by mixing the following raw materials in parts by weight: 100 parts of active minerals, 1-100 parts of solid alkali activator, 1-200 parts of distilled water, 1-200 parts of epoxy resin, and 0-30 parts of silane coupling agent, preferably 100 parts of active minerals, 1-80 parts of solid alkali activator, 1-100 parts of distilled water, 1-150 parts of epoxy resin, and 1-10 parts of silane coupling agent;

[0007] The plywood is prepared using the adhesive obtained by the above preparation method, and the preparation method includes the following steps: 1) ball milling pretreatment of active minerals; 2) pre-reaction treatment of active minerals and solid alkali activator; 3) preparation of mineral-based adhesive; 4) application of adhesive to wood veneer; 5) hot pressing of the board blank, followed by post-processing to obtain high-performance plywood for bulk solid waste recycling.

[0008] The active mineral is one or a mixture of several of the following: metakaolin, fly ash, coal gangue, slag, burnt clay, and rice husk ash, preferably fly ash and metakaolin; the solid alkali activator is prepared by uniformly mixing the following raw materials in parts by weight: 30-100 parts of silicate solid and 0-50 parts of alkaline powder, preferably 50-80 parts of sodium silicate solid and 1-30 parts of sodium hydroxide powder; the epoxy resin is bis(4-hydroxyphenyl)propane epichlorohydrin ether and bisphenol A-diphenyl ether. The silane coupling agent is one or a mixture of several of the following: glycidyl ether type epoxy resin, bis(4-hydroxyphenyl)propane diglycidyl ether, preferably bis(4-hydroxyphenyl)propane epichlorohydrin ether; the silane coupling agent is one or a mixture of several of the following: γ-aminopropyltriethoxysilane, γ-glycine ethyl ester trimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-propyl isocyanate trimethoxysilane, γ-vinyltriethoxysilane, preferably γ-aminopropyltriethoxysilane;

[0009] Specifically, the ball milling pretreatment step is as follows: a certain amount of active minerals are placed in a ball mill and ball milled at a speed of 50-500 r / min for 1-50 hours to obtain pretreated active minerals.

[0010] The pre-reaction treatment step is as follows: mix 100 parts of active minerals with 1-100 parts of solid alkali activator, add 1-200 parts of distilled water, mix evenly, and let stand at room temperature for 1-24 hours.

[0011] The epoxy resin is liquid or semi-solid; the epoxy equivalent is 180-195 g / eq, preferably 185-190 g / eq.

[0012] The amount of adhesive applied to the veneer is 100-500 g / m². 2 Preferably 200-400g / m 2 .

[0013] The wood veneer is made of poplar, eucalyptus, birch, fir, pine, linden, elm, or rubberwood.

[0014] The hot pressing process is characterized by a hot pressing pressure of 0.5-3 MPa, preferably 1-2 MPa; a hot pressing temperature of 100-200℃, preferably 140-160℃; and a hot pressing time of 0.3-3.0 minutes / mm, preferably 0.8-1.2 minutes / mm.

[0015] In another aspect, the present invention provides a high-performance mineral adhesive for the reuse of bulk solid waste prepared according to the above method, and plywood prepared using the adhesive.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. This invention uses a solid alkali activator instead of the traditional alkali activating liquid method, and the resulting adhesive has the advantages of easy control of solid content, convenient transportation, and simple process.

[0018] 2. By employing ball milling pretreatment and pre-reaction time treatment, this invention greatly improves the activity of mineral polymers, making the mineral polymer molecular network more compact. During the bonding and curing process, the adhesive forms more effective glue nails with the wood, thereby improving the bonding strength.

[0019] 3. By introducing epoxy resin, the present invention enables the mineral polymer and epoxy resin to form an organic-inorganic "brick and mortar" structure, thereby improving the strength and water resistance of the colloid and making the reinforcing effect more significant.

[0020] 4. This invention introduces a silane coupling agent to promote the formation of a "gradient" structure between the mineral polymer and the epoxy resin, thereby enhancing the structural strength and toughness at the interface between the adhesive and the wood.

[0021] 5. The main raw material used in this invention is active mineral material, which is a non-flammable inorganic material. Therefore, the resulting adhesive and the plywood prepared using the adhesive have good flame retardant properties.

[0022] 6. This invention makes full use of the active mineral substances in bulk solid waste to provide a high-performance, formaldehyde-free, flame-retardant, low-cost, and simple-process mineral adhesive, its preparation method, and plywood prepared using the adhesive, which is of great significance to my country's sustainable and high-quality development. Detailed Implementation

[0023] The following detailed description of specific embodiments further illustrates the present invention, and the advantages and features of the present invention will become clearer as the description unfolds. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Various modifications, combinations, or refinements can be made to the technical solutions of the present invention without departing from the essence of the invention, but all such modifications, combinations, or refinements fall within the scope of protection claimed by the present invention.

[0024] Unless otherwise specified, all materials, equipment, instruments, etc. used in the following embodiments are commercially available.

[0025] Comparison Example

[0026] To verify the reinforcing effect of the adhesive of the present invention and the plywood prepared therefrom, plywood using pure mineral adhesive as the adhesive was prepared under the same hot-pressing process conditions, including the following steps:

[0027] Step 1: Preparation of mineral adhesive. Mix 100 parts fly ash, 80 parts solid alkali activator, and 50 parts distilled water according to the specified mass ratio to obtain the mineral adhesive. The solid alkali activator consists of 100 parts sodium silicate solid and 50 parts sodium hydroxide powder.

[0028] Step 2: Glue application and assembly. Glue is applied to the veneers using a roller coating method, with a glue application rate of 300g / m² on each side. 2 The slab is made by cross-structure of three adjacent layers of single-layer slab.

[0029] Step 3: Hot pressing is performed at a pressure of 1.0 MPa, a temperature of 150°C, and a pressing time of 1 minute per millimeter. The edges are then trimmed and sanded to obtain the final product.

[0030] The bonding strength of plywood specimens was tested according to GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The bonding strength of the plywood prepared in this comparative example was 0.28 MPa, which does not meet the strength requirements for Class II plywood in the national standard.

[0031] Example 1

[0032] Step 1: Pretreatment of active minerals by ball milling. A certain amount of fly ash is put into a ball mill and milled at 300 r / min for 8 hours to obtain pretreated fly ash.

[0033] Step 2: Pre-reaction treatment of active minerals with solid alkali activator. Mix 100 parts fly ash with 80 parts solid alkali activator according to the specified mass ratio, add 50 parts distilled water, mix thoroughly, and let stand at room temperature for 4 hours to obtain pure mineral adhesive. The solid alkali activator consists of 100 parts solid sodium silicate and 50 parts sodium hydroxide powder.

[0034] Step 3: Glue application and assembly. Glue is applied to the veneers using a roller coating method, with a glue application rate of 300g / m² on each side. 2 The slab is made by cross-structure of three adjacent layers of single-layer slab.

[0035] Step 4: Hot pressing is performed at a pressure of 1.0 MPa, a temperature of 150°C, and a pressing time of 1 minute per millimeter. The edges are then trimmed and sanded to obtain the final product.

[0036] The bond strength of plywood specimens was tested according to GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The bond strength of the plywood prepared in this comparative example is 0.64 MPa, which meets the strength requirements for Class II plywood in the national standard.

[0037] Example 2

[0038] Step 1: Pretreatment of active minerals by ball milling. A certain amount of fly ash is put into a ball mill and ball-milled at 300 r / min for 8 hours to obtain pretreated fly ash.

[0039] Step 2: Pre-reaction treatment of the active minerals with a solid alkali activator. Mix 100 parts of fly ash with 80 parts of the solid alkali activator according to the specified mass ratio, add 50 parts of distilled water, mix thoroughly, and let stand at room temperature for 4 hours to obtain a pure mineral polymer. The solid alkali activator consists of 100 parts of solid sodium silicate and 50 parts of sodium hydroxide powder.

[0040] Step 3: Prepare the mineral adhesive. Mix 100 parts of the pretreated mineral polymer and 10 parts of bis(4-hydroxyphenyl)propane epichlorohydrin ether according to the mass ratio to obtain the mineral-based adhesive.

[0041] Step 4: Glue application and assembly. Glue is applied to the veneers using a roller coating method, with a glue application rate of 300g / m² on each side. 2 The slab is made by cross-structure of three adjacent layers of single-layer slab.

[0042] Step 5: The product is then subjected to a hot-pressing process at a pressure of 1.0 MPa, a temperature of 150°C, and a pressing time of 1 minute per millimeter. Finally, the edges are trimmed and sanded to obtain the final product.

[0043] The bond strength of plywood specimens was tested according to GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The bond strength of the plywood prepared in this comparative example is 1.08 MPa, which meets the strength requirements for Class II plywood in the national standard.

[0044] Example 3

[0045] Step 1: Pretreatment of active minerals by ball milling. A certain amount of fly ash is put into a ball mill and ball-milled at 300 r / min for 8 hours to obtain pretreated fly ash.

[0046] Step 2: Pre-reaction treatment of the active minerals with a solid alkali activator. Mix 100 parts of fly ash with 80 parts of the solid alkali activator according to the specified mass ratio, add 50 parts of distilled water, mix thoroughly, and let stand at room temperature for 4 hours to obtain a pure mineral polymer. The solid alkali activator consists of 100 parts of solid sodium silicate and 50 parts of sodium hydroxide powder.

[0047] Step 3: Prepare the mineral adhesive. Mix 100 parts of the pretreated mineral polymer and 10 parts of bis(4-hydroxyphenyl)propane epichlorohydrin ether according to the mass ratio to obtain a mixed slurry; add two parts of γ-aminopropyltriethoxysilane and stir evenly to obtain the mineral adhesive.

[0048] Step 4: Glue application and assembly. Glue is applied to the veneers using a roller coating method, with a glue application rate of 300g / m² on each side. 2 The slab is made by cross-structure of three adjacent layers of single-layer slab.

[0049] Step 5: The product is then subjected to a hot-pressing process at a pressure of 1.0 MPa, a temperature of 150°C, and a pressing time of 1 minute per millimeter. Finally, the edges are trimmed and sanded to obtain the final product.

[0050] The bonding strength of plywood specimens was tested according to GB / T 17657-2022 "Test Methods for Physical and Chemical Properties of Wood-based Panels and Decorative Wood-based Panels". The bonding strength of the plywood prepared in this comparative example is 1.28 MPa, which meets the strength requirements for Class II plywood in the national standard.

[0051] Table 1. Performance test results of glued specimens

[0052]

[0053] Test results show that:

[0054] Compared to the pure mineral polymer plywood of the control example, the test results of Example 1 show that the activity of the mineral polymer is greatly improved after ball milling pretreatment and pre-reaction time treatment, the molecular network of the mineral polymer is more compact, and the adhesive forms more effective glue nails with the wood during the bonding and curing process, which greatly improves the bonding strength. The test results of Example 2 show that the mineral polymer and epoxy resin form an organic-inorganic "brick and mortar" structure, which improves the strength and water resistance of the adhesive and the reinforcing effect is more significant. The test results of Example 3 show that the incorporation of silane coupling agent promotes the formation of a "gradient" structure between the mineral polymer and epoxy resin, which enhances the structural strength and toughness at the interface between the adhesive and the wood; and the formaldehyde release of the adhesive is close to 0.

Claims

1. A high-performance mineral-based adhesive for the recycling of bulk solid waste, characterized in that: The adhesive is prepared by mixing the following raw materials in parts by weight: 100 parts active minerals, 1-100 parts solid alkali activator, 1-200 parts distilled water, 1-200 parts epoxy resin, and 0-30 parts silane coupling agent; the active minerals are one or a mixture of several of metakaolin, fly ash, coal gangue, and slag; the epoxy resin is one or a mixture of several of bis(4-hydroxyphenyl)propane epichlorohydrin ether, bisphenol A-diglycidyl ether type epoxy resin, and bis(4-hydroxyphenyl)propane diglycidyl ether ether; the silane coupling agent is one or a mixture of several of γ-aminopropyltriethoxysilane, γ-glycine ethyl ester trimethoxysilane, and γ-mercaptopropyltriethoxysilane. Using the above adhesive, plywood is prepared by a method comprising the following steps: 1) ball milling pretreatment of active minerals; 2) pre-reaction treatment of active minerals with solid alkali activator; 3) preparation of mineral-based adhesive; 4) application of adhesive to wood veneer; 5) hot pressing of the board blank, followed by post-processing to obtain the final product.

2. The high-performance mineral-based adhesive as described in claim 1, characterized in that, The active minerals need to undergo ball milling pretreatment; the ball milling pretreatment steps are as follows: a certain amount of active minerals are put into a ball mill and ball milled at a speed of 50-500 r / min for 1-50 h to obtain pretreated active minerals.

3. The high-performance mineral-based adhesive as described in claim 1, characterized in that, The solid alkali activator is prepared by uniformly mixing the following raw materials in parts by weight: 30-100 parts of silicate solid and 0-50 parts of alkaline powder; the silicate solid is sodium silicate or potassium silicate or a mixture of the two; the alkaline powder is sodium hydroxide powder or potassium hydroxide powder or a mixture of the two.

4. The high-performance mineral-based adhesive as described in claim 1, characterized in that, The active minerals and solid alkali activator need to undergo a pre-reaction treatment; the pre-reaction treatment steps are as follows: mix 100 parts of active minerals with 1-100 parts of solid alkali activator, add 1-200 parts of distilled water, mix evenly, and let stand at room temperature for 1-24 hours.

5. The high-performance mineral-based adhesive as described in claim 1, characterized in that, The amount of adhesive applied to the veneer is 100-500 g / m². 2 .

6. The high-performance mineral-based adhesive as described in claim 1, characterized in that, The wood veneer is made of poplar, eucalyptus, birch, fir, pine, linden, elm, or rubberwood.

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