阅读说明：本技术 超高固含量的胶合板用环保胶黏剂、制备方法及其应用 (Environment-friendly adhesive with ultrahigh solid content for plywood, preparation method and application thereof ) 是由 赵中元 孙世静 于 2019-10-30 设计创作，主要内容包括：本发明公开了一种超高固含量的胶合板用环保胶黏剂,其组分按重量百分比包含以下成分：蔗糖100份,磷酸二氢铵20～40份,亚硫酸钠3～4份,聚丙烯酰胺2～3份,柠檬酸0.05～2份,水25～63份；所述胶合板用环保胶黏剂的固含量为70.6-85.6％。并公开了其制备方法,其在制备胶合板上的应用,以及制得的胶合板。本发明的提供的胶黏剂在合成过程中利用磷酸二氢铵对蔗糖水解与焦糖化反应的催化作用,形成低分子量预聚物,在固化过程中利用美拉德反应产生化学交联反应,胶黏剂的粘度适中,固含量可达70.6-85.6％,改善了传统胶合板用天然胶黏剂因粘度过大无法提高固含量的缺陷,提高热固化速率与胶合强度。(The invention discloses an environment-friendly adhesive with ultrahigh solid content for plywood, which comprises the following components in percentage by weight: 100 parts of cane sugar, 20-40 parts of ammonium dihydrogen phosphate, 3-4 parts of sodium sulfite, 2-3 parts of polyacrylamide, 0.05-2 parts of citric acid and 25-63 parts of water; the solid content of the environment-friendly adhesive for the plywood is 70.6-85.6%. Also discloses a preparation method thereof, application thereof in preparing plywood and the prepared plywood. The adhesive provided by the invention utilizes the catalytic action of ammonium dihydrogen phosphate on sucrose hydrolysis and caramelization reaction in the synthesis process to form a low molecular weight prepolymer, and utilizes the Maillard reaction to generate a chemical crosslinking reaction in the curing process, the viscosity of the adhesive is moderate, the solid content can reach 70.6-85.6%, the defect that the solid content cannot be increased due to overlarge viscosity of the traditional natural adhesive for plywood is overcome, and the heat curing rate and the bonding strength are increased.)

1. The environment-friendly adhesive for the plywood with the ultrahigh solid content comprises the following components in percentage by weight:

the method is characterized in that: the solid content of the environment-friendly adhesive for the plywood is 70.6-85.6%, and the viscosity range is 370-810 mPa.

2. The method for preparing the ultra-high solid content environment-friendly adhesive for plywood as claimed in claim 1, which comprises the following steps:

(1) mixing sucrose, citric acid and water, and stirring at a low speed at a temperature of 80-90 ℃ for reaction for 1-1.5 hours;

(2) adding ammonium dihydrogen phosphate into the reaction system, and stirring at a low speed at a temperature of between 90 and 100 ℃ for reaction for 1 to 3 hours;

(3) adding sodium sulfite into a reaction system, and stirring at a high speed at a temperature of 80-90 ℃ for reaction for 0.5-1 hour;

(4) and after the temperature of the reaction system is reduced to room temperature, adding polyacrylamide into the solution, and stirring at a low speed for 0.2-0.5 h.

3. The preparation method of the environment-friendly adhesive with ultra-high solid content for plywood as claimed in claim 2, characterized in that: the low-speed stirring is 170-200 r/min, and the high-speed stirring is 350-370 r/min.

4. The preparation method of the environment-friendly adhesive for plywood with ultrahigh solid content according to claim 2 or 3, which is characterized by comprising the following steps: the water is distilled water.

5. The use of the ultra-high solid content environmentally friendly adhesive for plywood as claimed in claim 1 in the preparation of plywood.

6. The use of claim 5, comprising the steps of: coating an environment-friendly adhesive for plywood on a single board, assembling 3 layers of plywood based on a vertical texture mode, and performing hot press molding, wherein the double-side adhesive applying amount is 180-220 g/m²The hot pressing temperature is 135-155 ℃, the pressure is 1-1.5 MPa, and the hot pressing time is 4-5 min.

7. A plywood produced by hot-pressing the environmentally friendly adhesive for plywood according to claim 1 with veneers.

Technical Field

The invention relates to an environment-friendly adhesive with ultrahigh solid content for plywood, a preparation method and application thereof.

Background

The synthetic resin adhesive causes pollution to the environment and gradually lacks petroleum resources, and the development of the environment-friendly adhesive mainly prepared from renewable raw materials becomes an important research method; the natural adhesive for the traditional plywood is modified by adopting isolated soy protein or starch mostly, the solid content of the adhesive is low, the viscosity of the adhesive is high, the problems of water spraying, coating and scraping and the like exist in the application process, and the use is inconvenient, so that the development of the natural adhesive with ultrahigh solid content and low viscosity has important practical significance.

Disclosure of Invention

The invention aims to provide an environment-friendly adhesive with ultrahigh solid content for plywood. The adhesive utilizes the catalysis effect of ammonium dihydrogen phosphate on the sucrose caramelization reaction to form a low-molecular-weight prepolymer, the solid content can reach 70.6-85.6%, the defect that the solid content cannot be increased due to overlarge viscosity of the traditional natural adhesive for the plywood is overcome, and the heat curing rate and the bonding strength are increased.

The technical scheme of the invention is as follows:

the environment-friendly adhesive for the plywood with the ultrahigh solid content comprises the following components in percentage by weight:

the solid content of the environment-friendly adhesive for the plywood is 70.6-85.6%, and the viscosity range is 370-810 mPa.

The invention also discloses a preparation method of the environment-friendly adhesive for the plywood with the ultrahigh solid content, which comprises the following steps:

(1) mixing sucrose, citric acid and water, and stirring at a low speed at a temperature of 80-90 ℃ for reaction for 1-1.5 hours;

(2) adding ammonium dihydrogen phosphate into the reaction system, and stirring at a low speed at a temperature of between 90 and 100 ℃ for reaction for 1 to 3 hours;

(3) adding sodium sulfite into a reaction system, and stirring at a high speed at a temperature of 80-90 ℃ for reaction for 0.5-1 hour;

(4) and after the temperature of the reaction system is reduced to room temperature, adding polyacrylamide into the solution, and stirring at a low speed for 0.2-0.5 h.

Preferably, the low-speed stirring is 170-200 r/min, and the high-speed stirring is 350-370 r/min.

Preferably, the water is distilled water.

The invention also discloses an application of the environment-friendly adhesive for the plywood with the ultrahigh solid content in preparation of the plywood.

Preferably, the steps include: coating an environment-friendly adhesive for plywood on a single board, assembling 3 layers of plywood based on a vertical texture mode, and performing hot press molding, wherein the double-side adhesive applying amount is 180-220 g/m²The hot pressing temperature is 135-155 ℃, the pressure is 1-1.5 MPa, and the hot pressing time is 4-5 min.

The invention also discloses a plywood which is formed by hot pressing the veneer and the environment-friendly adhesive for the plywood.

The invention has the following beneficial effects:

the raw materials used in the invention have good water solubility, the viscosity of the saturated aqueous solution of the body is low, the solid content is low, and the adhesive is not suitable for being used for wood plywood, so that the sucrose is subjected to hydrolysis reaction in a small amount of distilled water by improving the synthesis process, and the solid content of the synthesized adhesive can reach 70.6-85.6%. Under the catalytic action of ammonium dihydrogen phosphate and sodium sulfite, the sucrose hydrolysate undergoes chemical structure rearrangement, and under the action of amino, a furan compound with high reaction activity is formed, so that the generation of high molecular polymers can be effectively promoted, and the bonding strength is remarkably improved. Because the prepared adhesive needs dehydration condensation in the using process, the polyacrylamide is added as a dehydrating agent, the curing efficiency of the adhesive can be promoted, the curing rate is improved, and the bonding strength is further improved.

During the reaction process of sucrose and ammonium dihydrogen phosphate, furfural is formed under the low-temperature condition by utilizing the catalytic action of ammonium ions on sucrose hydrolysis and conversion, and then NH formed after pyrolysis of furfural and ammonium dihydrogen phosphate₃Generates amadori rearrangement reaction, and the formed polymer is mostly furan polymer, has high strength and stable performance, and can be used for preparing artificial boards.

Detailed Description

For better understanding of the present invention, the technical solution of the present invention will be described in detail with specific examples, but the present invention is not limited thereto.