Glue-free cork board and preparation method thereof

Abstract

The invention belongs to a non-adhesive cork board and a preparation method thereof, and the method comprises the following steps: pretreating cork particles through a metal salt solution and carrying out hot press molding to realize non-adhesive bonding. The method comprises the specific steps that cork particles with the particle size being 2-6 mm are soaked in a metal salt solution with the concentration being 0.5 g / L-20.0 g / L for 10-30 min, and the mass ratio of metal salt to the cork particles is 1: 10-1: 100; taking out and drying until the water content is 8-12%; and carrying out hot pressing for 30-60 minutes at the temperature of 80-130 DEG C and the pressure of 4-8 MPa to obtain the glue-free cork board. According to the invention, the coordination crosslinking effect of metal ions and cork polyphenol is utilized, a synthetic resin adhesive is not needed, the product has no formaldehyde release, the process is simple, the cost is low, the internal bonding strength of the obtained cork board reaches 0.7-1.5 MPa, the tensile strength is 1.5-4.5 MPa, and the cork board is suitable for the field of environment-friendly building materials.

Description

Technical Field

[0001] The invention relates to a glue-free cork board and a preparation method thereof. Background Art

[0002] As a natural porous material, cork board has excellent elastic recovery, sound absorption and sound insulation performance, thermal insulation properties and shock absorption and buffering effects due to its unique cell structure. It is widely used in architectural decoration, home flooring, industrial sealing and other fields. The industrial preparation of traditional cork board mainly adopts the particle bonding process, that is, cork particles are mixed with synthetic resin adhesives such as phenolic, polyurethane, melamine formaldehyde, etc., and then the board is prepared by hot pressing. Although this process is mature and stable, there are several significant problems: (1) The cost of adhesives usually accounts for 30-45% of the total cost of raw materials, which significantly increases the production cost; (2) Commonly used aldehyde resins will continuously release free formaldehyde during curing and use, causing indoor air pollution and endangering human health; (3) The addition of adhesives will partially block the natural pore structure of cork, reducing its elastic recovery, air permeability and moisture absorption and humidity control functions. With the increasingly stringent global environmental protection regulations and the rapid growth of consumer demand for green building materials, the development of completely adhesive-free environmentally friendly cork board preparation technology has become an urgent need in the industry. Especially in places like infant and toddler facilities and medical settings, the requirements for material safety and non-toxicity are even more stringent. Therefore, there is an urgent need for innovative adhesive-free molding technologies that are based on purely physical processing, have simple processes, and preserve the natural properties of cork. This will not only break through existing technical bottlenecks but also promote the development of the entire cork products industry in a more environmentally friendly and sustainable direction. Summary of the Invention

[0003] The purpose of the present invention is to design a glue-free cork board and a preparation method thereof, which is green and environmentally friendly, has low production cost, is safe and reliable, and has strong mechanical properties.

[0004] To this end, a method for preparing a non-glue cork board of the present invention comprises the following steps: (1) Soaking treatment: Soaking cork particles with a particle size of 2 to 6 mm in an aqueous solution of a metal salt at room temperature for 10 to 30 minutes to obtain salt-soaked cork particles; (2) Drying treatment: Dry the salt-soaked cork pellets to a moisture content of 8-12% to obtain dry salt-soaked cork pellets; (3) Hot pressing: The dried salt-soaked cork particles are hot pressed at 80-130°C and 4-8 MPa pressure for 30-60 minutes to produce glue-free cork boards.

[0005] As a further description of the above technical solution: the metal salt is one or more of sodium salt, magnesium salt, aluminum salt, potassium salt, calcium salt, iron salt, zinc salt, copper salt or their complex salts.

[0006] As a further description of the above technical solution: the preferred metal salts are calcium salts and iron salts.

[0007] As a further description of the above technical solution: the concentration of the metal salt aqueous solution is 0.5g / L to 20.0g / L, and the mass ratio of the metal salt to the cork particles is 1:10 to 1:100.

[0008] As a further description of the above technical solution: the cork particles include cork oak bark material and low-hardness wood with a JanKa hardness of ﹤400.

[0009] As a further description of the above technical solution: the low-hardness wood is one or more of balsa wood, paulownia, horse chestnut, and North American cedar.

[0010] As a further description of the above technical solution: the weight of the cork particles made of low-hardness wood in the prepared glue-free cork board accounts for 0-8%, and the rest are cork particles made of cork oak bark materials.

[0011] As a further description of the above technical solution: the preferred hot pressing conditions are 100-110°C, 5-7MPa, and 40-50 minutes.

[0012] The invention discloses a glue-free cork board which is formed by soaking cork particles in a metal salt aqueous solution and then drying and hot pressing the cork particles.

[0013] As a further description of the above technical solution: the internal bonding strength of the glue-free cork board is 0.7-1.5 MPa, and the tensile strength is 1.5-4.5 MPa.

[0014] The present invention has the following beneficial effects: 1. The present invention produces adhesive-free cork boards by soaking cork particles in an aqueous solution of metal salts, followed by drying and heat-pressing. This method eliminates the use of traditional synthetic adhesives such as phenolic and urea-formaldehyde resins. Instead, the present invention achieves adhesion through the coordination of cork's polyphenols with metal ions, fundamentally avoiding the release of formaldehyde and VOCs. The product meets green building material standards, is harmless to humans and the environment, and achieves zero formaldehyde emission in particleboard. Compared to particleboard produced by other methods, the particleboard of the present invention is more environmentally friendly and superior to most previously reported particleboards.

[0015] 2. The process of the present invention is simple, requiring only three steps: soaking in metal ion solution, drying and hot pressing. It is easy to operate and suitable for industrial production.

[0016] 3. The present invention offers the advantages of low cost and good economic benefits. The metal salts used in the present invention are inexpensive and used in small quantities. Furthermore, the addition of low-hardness wood increases the overall strength of the corkboard while significantly reducing raw material costs. Furthermore, the present invention utilizes a relatively low hot-pressing temperature, saving significant energy. Preliminary calculations indicate that the present invention reduces the production cost by 25-30% compared to conventional glued corkboard. The raw materials used in the present invention are readily available, have a wide range of sources, and are flexible in proportion, making them suitable for mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the mechanical properties and internal bonding strength of glue-free cork boards. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. In order to make the technical means, creative features, purpose and efficacy of the present invention easy to understand, the present invention will be further described in conjunction with specific embodiments below. However, the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention. The construction methods in the following embodiments are all conventional methods unless otherwise specified. The materials, devices, equipment, etc. used in the following embodiments are all commercially available unless otherwise specified.

[0019] Example 1: 40g of cork pellets made from cork oak bark were weighed and soaked in an aqueous solution containing potassium chloride for 10 minutes at room temperature. The cork pellets had a particle size of 2mm, the potassium chloride aqueous solution had a concentration of 0.5g / L, and the mass ratio of potassium chloride to cork pellets was 1:10. The soaked cork pellets were removed and dried to a moisture content of 10%. The dried cork pellets were assembled and hot-pressed at 110°C and 4MPa for 40 minutes to produce a glue-free cork board.

[0020] The internal bonding strength of the glue-free cork board was measured to be 0.5 MPa, the tensile strength was 2 MPa, and the thickness expansion rate of water absorption after 24 hours was 5%.

[0021] Example 2: Weigh 40g of cork pellets, including 37g of cork pellets made from cork oak bark, 1g of cork pellets made from balsa wood, 1g of cork pellets made from paulownia, and 1g of cork pellets made from cedar. The pellets were mixed and soaked in an aqueous solution containing aluminum chloride for 10 minutes at room temperature. The cork pellets had a particle size of 2mm, the concentration of the aluminum chloride solution was 0.5g / L, and the mass ratio of aluminum chloride to cork pellets was 1:10. The soaked cork pellets were removed and dried to a moisture content of 10%. The dried pellets were assembled and hot-pressed at 110°C and 4 MPa for 40 minutes to produce a glue-free cork board.

[0022] The internal bonding strength of the non-glue cork board was measured to be 0.9 MPa, the tensile strength was 3.25 MPa, and the thickness expansion rate after 24 hours of water absorption was 3%.

[0023] Example 3: 40g of cork pellets made from cork oak bark were weighed and soaked in an aqueous solution containing potassium chloride for 15 minutes at room temperature. The cork pellets had a particle size of 4mm, the potassium chloride aqueous solution had a concentration of 1.0g / L, and the mass ratio of potassium chloride to cork pellets was 1:20. The soaked cork pellets were removed and dried to a moisture content of 12%. The dried cork pellets were assembled and hot-pressed at 130°C and 4MPa for 30 minutes to produce a glue-free cork board.

[0024] The internal bonding strength of the glue-free cork board was measured to be 0.7 MPa, the tensile strength was 2.5 MPa, and the 24h water absorption thickness expansion rate was 4%.

[0025] Example 4: 40g of cork pellets were weighed, including 37g of cork pellets made from cork oak bark, 2g of cork pellets made from balsa wood, and 1g of cork pellets made from paulownia. These pellets were soaked in an aqueous solution containing aluminum chloride for 15 minutes at room temperature. The cork pellets had a particle size of 4mm, the concentration of the aluminum chloride solution was 0.5g / L, and the mass ratio of aluminum chloride to cork pellets was 1:15. The soaked cork pellets were removed and dried to a moisture content of 12%. The dried cork pellets were assembled and hot-pressed at 130°C and 4 MPa for 30 minutes to produce a glue-free cork board.

[0026] The internal bonding strength of the non-glue cork board was measured to be 1.1 MPa, the tensile strength was 3.5 MPa, and the thickness expansion rate of water absorption after 24 hours was 3%.

[0027] Example 5: 40g of cork pellets, including 36.5g of cork pellets made from cork oak bark and 3.5g of cork pellets made from balsa wood, were weighed and soaked in an aqueous solution containing ferric chloride for 10 minutes at room temperature. The cork pellets had a particle size of 6mm, the concentration of the ferric chloride solution was 0.5g / L, and the mass ratio of ferric chloride to cork pellets was 1:10. The soaked cork pellets were removed and dried to a moisture content of 12%. The dried cork pellets were assembled and hot-pressed at 110°C and 6 MPa for 40 minutes to produce a glue-free cork board.

[0028] The internal bonding strength of the non-glue cork board was measured to be 1.3 MPa, the tensile strength was 3.85 MPa, and the thickness expansion rate of water absorption after 24 hours was 2%.

[0029] like Figure 1 As shown: The mechanical properties and internal bonding strength of the obtained glue-free cork board will be different depending on the composition of the cork particles and the selected metal salt solutions, and should be set according to the planned product indicators.

[0030] The above is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a non-glue cork board, characterized in that: The steps include: (1) Soaking treatment: Soaking cork particles with a particle size of 2 to 6 mm in an aqueous solution of a metal salt at room temperature for 10 to 30 minutes to obtain salt-soaked cork particles; (2) Drying treatment: Dry the salt-soaked cork pellets to a moisture content of 8-12% to obtain dry salt-soaked cork pellets; (3) Hot pressing: The dried salt-soaked cork particles are hot pressed at 80-130°C and 4-8 MPa pressure for 30-60 minutes to produce glue-free cork boards.

2. The method for preparing a non-glue cork board according to claim 1, characterized in that: The metal salt is one or more of sodium salt, magnesium salt, aluminum salt, potassium salt, calcium salt, iron salt, zinc salt, copper salt or their complex salts.

3. The method for preparing a non-glue cork board according to claim 2, characterized in that: The preferred metal salts are calcium salts and iron salts.

4. The method for preparing a non-glue cork board according to claim 1, characterized in that: The concentration of the metal salt aqueous solution is 0.5 g / L to 20.0 g / L, and the mass ratio of the metal salt to the cork particles is 1:10 to 1:

100.

5. The method for preparing a non-glue cork board according to claim 1, characterized in that: The cork particles include cork oak bark materials and low-hardness wood with a JanKa hardness of less than 400.

6. The method for preparing a non-glue cork board according to claim 5, characterized in that: The low-hardness wood is one or more of balsa wood, paulownia, horse chestnut, and North American cedar.

7. The method for preparing a non-glue cork board according to claims 1 and 5, characterized in that: In the prepared glue-free cork board, the weight proportion of cork particles made of low-hardness wood is 0-8%, and the rest is cork particles made of cork oak bark materials.

8. The method for preparing a non-glue cork board according to claim 1, characterized in that: The preferred hot pressing conditions are 100-110° C., 5-7 MPa, and 40-50 minutes.

9. The particleboard prepared according to the preparation method according to any one of claims 1 to 8, characterized in that: The glue-free cork board is formed by soaking cork particles in an aqueous solution of metal salts, drying them, and then hot pressing them.

10. The glue-free cork board according to claim 9, characterized in that: The internal bonding strength of the non-glue cork board is 0.7-1.5 MPa, and the tensile strength is 1.5-4.5 MPa.

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