阅读说明：本技术 超高固含量的柠檬酸基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 citric acid-based 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柠檬酸基胶合板用环保胶黏剂,其组分按重量百分比包含以下成分：柠檬酸100份,蔗糖25～30份,氯化铜3～5份,氧化钙2～5份,无水乙醇10～15份,水15～28份；所述胶合板用环保胶黏剂的固含量为75.1～84.8％,粘度范围为277～537mPa·s。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利用柠檬酸对蔗糖水解以及转化的催化作用,形成低分子量预聚物,胶黏剂的粘度适中,固含量可达75.1～84.8％,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,本发明同时采用乙醇水溶液调节胶黏剂粘度,降低水分含量,提高了热固化效率,降低了热固化温度。(The invention discloses an environment-friendly adhesive with ultrahigh solid content for citric acid-based plywood, which comprises the following components in percentage by weight: 100 parts of citric acid, 25-30 parts of cane sugar, 3-5 parts of copper chloride, 2-5 parts of calcium oxide, 10-15 parts of absolute ethyl alcohol and 15-28 parts of water; the solid content of the environment-friendly adhesive for the plywood is 75.1-84.8%, and the viscosity range is 277-537 mPa. 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 citric acid on hydrolysis and conversion of sucrose to form a low molecular weight prepolymer, the viscosity of the adhesive is moderate, the solid content can reach 75.1-84.8%, the defect that the solid content cannot be increased due to overlarge viscosity of the traditional natural adhesive for plywood is overcome, the viscosity of the adhesive is adjusted by adopting an ethanol aqueous solution, the moisture content is reduced, the thermosetting efficiency is improved, and the thermosetting temperature is reduced.)

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

100 parts of citric acid;

25-30 parts of cane sugar;

3-5 parts of copper chloride;

2-5 parts of calcium oxide;

10-15 parts of absolute ethyl alcohol;

15-28 parts of water;

the method is characterized in that: the solid content of the environment-friendly adhesive for the citric acid-based plywood is 75.1-84.8%, and the viscosity range is 277-537 mPa.

2. The method for preparing the ultra-high solid content environmental protection adhesive for citric acid based plywood of claim 1, which comprises the following steps: (1) mixing sucrose, copper chloride and water, and stirring at a low speed at a temperature of 70-80 ℃ for reaction for 1-1.5 hours;

(2) adding citric acid into the reaction system, and stirring at a low speed at 90-100 ℃ for reaction for 1-3 hours;

(3) adding absolute ethyl alcohol into the 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 calcium oxide into the solution, and stirring at a low speed for 0.2-0.5 h.

3. The method for preparing the environmentally friendly adhesive for the ultra-high solid content citric acid-based plywood according to claim 2,

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 the ultra-high solid content citric acid-based plywood as claimed in claim 2 or 3, wherein the preparation method comprises the following steps: the water is distilled water.

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

6. The use of claim 5, comprising the steps of: coating an environment-friendly adhesive for a citric acid-based plywood on a single board, assembling a multi-layer plywood based on a vertical texture mode, and performing hot press molding, wherein the double-side adhesive applying amount is 160-200 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. Use according to claim 5, characterized in that: the multilayer plywood is 3 layers of plywood.

8. A plywood produced by hot-pressing the environmentally-friendly adhesive for citric acid-based plywood with ultrahigh solid content according to claim 1 and veneers.

Technical Field

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

Background

Synthetic resin adhesives are generally prepared by taking petroleum extracts as main raw materials, and volatile organic compounds are released in the using process to pollute the environment; meanwhile, in consideration of the gradual shortage of petroleum resources, the development and application of environment-friendly adhesives taking renewable resources as main raw materials become key problems to be solved urgently in the wood adhesive industry; the traditional natural adhesive for the 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 application process has the problems of high requirement on the flatness of materials, the need of adjusting the viscosity and the like, and the use is inconvenient, so that the development of the natural adhesive with ultrahigh solid content and low viscosity has important practical significance for expanding the application of the natural adhesive. The traditional citric acid-based adhesive adopts a sucrose adding mixing mode, the viscosity of the prepared adhesive is too low, the particle board can be prepared only in a spraying mode, and the preparation of the plywood cannot be carried out, so that the application field of a citric acid-sucrose bonding system can be expanded by developing the novel citric acid-based adhesive.

Disclosure of Invention

The invention aims to provide an environment-friendly adhesive with ultrahigh solid content for citric acid-based plywood.

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:

100 parts of citric acid;

25-30 parts of cane sugar;

3-5 parts of copper chloride;

2-5 parts of calcium oxide;

10-15 parts of absolute ethyl alcohol;

15-28 parts of water;

the solid content of the environment-friendly adhesive for the plywood is 75.1-84.8%, and the viscosity range is 277-537 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, copper chloride and water, and stirring at a low speed at a temperature of 70-80 ℃ for reaction for 1-1.5 hours;

(2) adding citric acid into the reaction system, and stirring at a low speed at 90-100 ℃ for reaction for 1-3 hours;

(3) adding absolute ethyl alcohol into the 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 calcium oxide 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 a multi-layer plywood based on a vertical texture mode, and performing hot press molding, wherein the double-side adhesive applying amount is 160-200 g/m²The hot pressing temperature is 135-155 ℃, the pressure is 1-1.5 MPa, and the hot pressing time is 4-5 min.

Preferably, the multilayer plywood is 3-layer plywood

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:

according to the adhesive disclosed by the invention, a low-molecular-weight prepolymer is formed by utilizing the catalytic action of citric acid and copper chloride on the caramelization reaction of sucrose, the defect that the solid content of the traditional natural adhesive for plywood cannot be increased due to overlarge viscosity is overcome, and the viscosity of the adhesive is prepared by adding absolute ethyl alcohol, so that the thermosetting speed and the bonding strength are increased.

The raw materials used in the invention have good water solubility, the viscosity of a saturated aqueous solution of the self-body is low, the solid content is low, and the self-body is not suitable for being used for the wood plywood, therefore, the invention enables sucrose to be subjected to hydrolysis reaction in a small amount of distilled water by improving the synthesis process, the solid content of the synthesized adhesive can reach 75.1-84.8%, and the viscosity range is 277-537 mPa.s.

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.