Plywood and processing method for improving curing efficiency of plywood glue layer

Abstract

The present invention belongs to the technical field of artificial board processing, and relates to a processing method for improving the curing efficiency of plywood glue layer. When plywood is assembled, a glass fiber mesh cloth impregnated with a curing agent is added between the veneer glue layers of two adjacent wood veneers. Based on the above method, the present invention also provides a plywood. The curing agent is impregnated on the glass fiber mesh cloth, which slows down the reaction of the curing agent and the phenolic resin glue, and solves the problem of rapid increase in adhesive viscosity and difficulty in coating caused by the overly rapid reaction of the curing agent propylene carbonate and the phenolic resin glue.

Description

Technical Field

[0001] The invention belongs to the technical field of artificial board processing, and relates to an adhesive for a wood composite board, in particular to a plywood and a processing method for improving the curing efficiency of a plywood glue layer. Background Art

[0002] Plywood is produced through log peeling, drying, veneer gluing and hot pressing. The adhesive used for water-resistant plywood is mainly phenolic resin glue with low cost and good performance. Phenolic resin glue is cured under certain temperature conditions and consumes a lot of energy. The low curing efficiency of the glue layer and the high energy consumption are the problems in the wood-based panel processing industry.

[0003] In the patent application with publication number CN103834337A, a fast-curing phenolic resin for wood structure made with one of paraformaldehyde, hexamethylenetetramine, glyoxal solution or formaldehyde solution as curing agent is disclosed. In the patent application with publication number CN101067016A, a fast-curing phenolic resin with mixed acidic halogen compounds as curing agent is disclosed, but it is mainly used as an impregnating resin; in the patent application with publication number CN104212123A, a curing agent for alkaline phenolic resin comprising a polymethylol urea mixture, carbonate, organic ester compound, polyvinyl alcohol and water is disclosed. Although the above technical scheme plays a certain role in the rapid curing of phenolic resin, the manufacturing method of the adhesive is relatively complicated.

[0004] In the article "The Effect of Propylene Carbonate Curing Agent on the Curing Performance of Phenolic Resin" published by Huang Jianfeng et al. in the Journal of Fujian Agriculture and Forestry University, Vol. 43, No. 1 (January 2014), it is introduced that the curing effect of propylene carbonate is too strong. Although it can significantly promote the curing of resin, adding 4% will result in a too short applicability period after the glue is adjusted; in the three-layer plywood test, when the addition amount of propylene carbonate is 2%, the applicability period can also meet the production requirements. If the amount of propylene carbonate is further increased, the glue will gradually become viscous and it will be difficult to apply the glue. Even if the glue has been applied to the surface of the veneer, it is difficult for the glue to wet the wood surface, causing defects in the bonding interface and resulting in a decrease in bonding strength. It is generally understood in this field that the amount of propylene carbonate added should not exceed 4%. Since propylene carbonate reacts strongly with phenolic resin glue, the viscosity increases rapidly in a short period of time, and the adhesive cannot be evenly coated in time, which seriously affects the use of the curing agent. On the one hand, the amount of propylene carbonate used is limited, which affects the improvement of the curing efficiency of the adhesive layer. On the other hand, if the amount of propylene carbonate added exceeds a certain proportion, the adhesive viscosity will increase rapidly and coating will be difficult. Summary of the invention

[0005] The purpose of the present invention is to provide a processing method for improving the curing efficiency of the plywood glue layer in view of the above problems.

[0006] The object of the present invention is to provide a plywood in view of the above problems.

[0007] The present invention creatively proposes a processing method for improving the curing efficiency of the plywood glue layer. When the plywood is assembled, a glass fiber mesh cloth impregnated with a curing agent is added between the veneer glue layers of adjacent wood veneers. The curing agent is impregnated on the glass fiber mesh cloth, which slows down the reaction of the curing agent with the phenolic resin glue, and solves the problem of rapid increase in adhesive viscosity and difficulty in coating caused by the overly rapid reaction of the curing agent propylene carbonate with the phenolic resin glue.

[0008] In the above processing method for improving the curing efficiency of the plywood glue layer, the curing agent comprises propylene carbonate and a silane coupling agent. The curing agent propylene carbonate promotes the reaction of the phenolic resin glue and accelerates the curing efficiency of the glue layer.

[0009] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the curing agent is composed of propylene carbonate and silane coupling agent in a mass ratio of 100:6-12.

[0010] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the plywood assembly veneer glue layer is a phenolic resin glue containing phenolic resin.

[0011] Phenolic resin glue also contains flour. By mixing flour and phenolic resin, a better gluing effect can be achieved.

[0012] In the above processing method for improving the curing efficiency of the plywood glue layer, the ratio of the amount of propylene carbonate added to the phenolic resin glue is greater than or equal to 4%. The processing method provided by the present invention overcomes the technical prejudice in the field, increases the amount of propylene carbonate added, and thus improves the curing efficiency.

[0013] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the mass of the curing agent in the glass fiber mesh cloth impregnated with the curing agent is 40% to 60% of the mass of the glass fiber mesh cloth.

[0014] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the gram weight of the glass fiber mesh cloth is 60-120 g / m 2 , which is conducive to the mutual penetration of glue.

[0015] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the wood veneer is coated with glue to form a veneer glue layer, and a glass fiber mesh cloth impregnated with a curing agent is added between adjacent veneer glue layers to form a blank, and the blank is placed in a hot press, and hot pressing is performed at a temperature of 120 to 128°C, a time of 0.6 to 0.8 min / mm, and a pressure of 2.5 to 4.5 MPa to obtain a plywood product. During the hot pressing process of the plywood, under the action of temperature, the curing agent propylene carbonate promotes the reaction of the phenolic resin glue and accelerates the curing efficiency of the glue layer. The hot pressing time is appropriately reduced.

[0016] In the above-mentioned processing method for improving the curing efficiency of the plywood glue layer, the mesh size of the glass fiber mesh cloth is 3*3mm, 4*4mm or 5*5mm.

[0017] In the above processing method for improving the curing efficiency of the plywood glue layer, a glass fiber mesh cloth impregnated with a curing agent is added between every two layers of wood veneer, and the width of the glass fiber mesh cloth is consistent with the width of the plywood blank to be produced.

[0018] The present invention also creatively proposes a plywood processed by the method.

[0019] Compared with the prior art, the advantages of the present invention are:

[0020] 1) The present invention impregnates the curing agent on the glass fiber mesh cloth, slowing down the reaction between the curing agent and the phenolic resin adhesive, and solving the problem of rapid increase in adhesive viscosity and difficulty in coating caused by the overly rapid reaction between the curing agent propylene carbonate and the phenolic resin adhesive.

[0021] 2) The present invention overcomes the technical prejudice in the art and increases the amount of propylene carbonate added. The curing agent propylene carbonate promotes the reaction of the phenolic resin glue and accelerates the curing efficiency of the glue layer. DETAILED DESCRIPTION

[0022] Further illustrated by the following specific examples;

[0023] Example 1

[0024] The curing agent used is propylene carbonate and silane coupling agent CG550, which are evenly mixed in a mass ratio of 100:9 to prepare an impregnation curing agent for use.

[0025] Phenolic resin glue: flour = 100:8 are mixed evenly to prepare phenolic resin glue for later use.

[0026] A glass fiber mesh cloth with a mesh size of 5*5 mm is impregnated with a curing agent. After the glass fiber mesh cloth is impregnated with the curing agent, the added mass of the curing agent is controlled to be 55% of the mass of the glass fiber mesh cloth.

[0027] 11 layers of pine veneer are used to produce plywood, the thickness of the veneer is 1.5mm and the thickness of the assembly is 16.5mm.

[0028] The wood veneer is coated with phenolic resin glue by a glue coating machine, so that the glue coating amount on one side of the wood veneer is 90g / m 2 The veneer boards are assembled, and a glass fiber mesh cloth impregnated with a curing agent is added between every two layers of veneer boards. The width of the glass fiber mesh cloth is consistent with the width of the plywood to be produced.

[0029] The wood veneer is coated with glue and assembled into a blank, which is then put into a hot press and hot pressed at a temperature of 125°C, a time of 0.6 min / mm, and a pressure of 2.5 MPa to obtain a plywood product.

[0030] Example 2

[0031] The curing agent used is propylene carbonate and silane coupling agent CG550, which are evenly mixed in a mass ratio of 100:8 to prepare an impregnation curing agent for use.

[0032] Phenolic resin glue: flour = 100:6 are mixed evenly to prepare phenolic resin glue for later use.

[0033] A glass fiber mesh cloth with a mesh size of 4*4 mm is impregnated with a curing agent. After the glass fiber mesh cloth is impregnated with the curing agent, the added mass of the curing agent is controlled to be 50% of the mass of the glass fiber mesh cloth.

[0034] 19-layer Abitong veneer is selected to produce plywood, the thickness of the wood veneer is 1.6mm and the thickness of the assembly is 30.4mm.

[0035] The wood veneer is made by coating phenolic resin glue with a glue coating machine, so that the glue coating amount on one side of the wood veneer is 100g / m 2 A glass fiber mesh cloth impregnated with curing agent is added between every two layers of wood veneer, and the width of the glass fiber mesh cloth is consistent with the width of the plywood produced.

[0036] The wood veneer is coated with glue and assembled into a blank, which is then put into a hot press and hot pressed at a temperature of 128°C, a time of 0.8 min / mm, and a pressure of 3.2 MPa to obtain a plywood product.

[0037] The plywood laminated by the above technical solution was tested for bonding strength and immersion peeling performance according to GB / T9846-2015 ordinary plywood Class I plywood. The results are as follows:

[0038]

[0039] The results show that the plywood processed by the present invention overcomes the technical prejudice in the art, and can still ensure the bonding strength and accelerate the curing efficiency of the adhesive layer when the amount of propylene carbonate added is increased.

[0040] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

[0041] Although the terms such as plywood assembly, wood veneer, veneer glue layer, impregnation curing agent, propylene carbonate, silane coupling agent, glass fiber mesh cloth, etc. are used more frequently in this article, these terms are used only to more conveniently describe and explain the essence of the present invention, and interpreting them as any additional limitations is contrary to the spirit of the present invention.

Claims

1. A processing method for improving the curing efficiency of plywood glue layer, characterized in that: When plywood is assembled, a glass fiber mesh cloth impregnated with a curing agent is added between the veneer glue layers of two adjacent wood veneers, the curing agent comprises propylene carbonate and a silane coupling agent, the veneer glue layers of the plywood assembly are phenolic resin glue comprising phenolic resin, and the ratio of the added amount of propylene carbonate to the phenolic resin glue is greater than or equal to 4%.

2. A processing method for improving the curing efficiency of plywood glue layer according to claim 1, characterized in that: The curing agent is composed of propylene carbonate and a silane coupling agent in a mass ratio of 100:6-12.

3. A processing method for improving the curing efficiency of plywood glue layer according to claim 1, characterized in that: The mass of the curing agent in the glass fiber mesh cloth impregnated with the curing agent is 40% to 60% of the mass of the glass fiber mesh cloth.

4. A processing method for improving the curing efficiency of plywood glue layer according to claim 1, characterized in that: The gram weight of the glass fiber mesh cloth is 60-120 g / m 2 .

5. A processing method for improving the curing efficiency of plywood glue layer as claimed in claim 1, characterized in that: The wood veneer is coated with glue to form a veneer glue layer, and glass fiber mesh cloth impregnated with a curing agent is added between adjacent veneer glue layers to form a blank board. The blank board is put into a hot press and hot pressed at a temperature of 120-128°C, a time of 0.6-0.8min / mm, and a pressure of 2.5-4.5MPa to obtain a plywood product.

6. A processing method for improving the curing efficiency of plywood glue layer according to claim 1, characterized in that: The mesh size of the glass fiber mesh cloth is 3*3mm, 4*4mm or 5*5mm.

7. A plywood processed by the method according to any one of claims 1 to 6.

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