阅读说明：本技术 一种改性大豆基胶黏剂的制备方法 (Preparation method of modified soybean-based adhesive ) 是由 陈涛 徐益忠 于 2020-05-28 设计创作，主要内容包括：本发明公开了一种改性大豆基胶黏剂的制备方法,包括对摩尔比为1：1的二乙烯三胺和己二酸缓慢加热至190℃发生酰胺化反应,至反应产生的水分脱除后,在190℃下保持反应6~11h,得到反应母液；向反应母液中加环氧氯丙烷,环氧氯丙烷与二乙烯三胺的摩尔比为1.05~1.2：1,持续搅拌升温至50~90℃,调节粘度值到25~100mPa.s后,停止反应；调节PH值得到改性剂,向改性剂中加入脱脂豆粉,得到大豆基胶黏剂。制备的大豆基胶黏剂固含量可调,在使用中能够顾调节胶黏剂的黏度和涂层厚度,应用范围广。(The invention discloses a preparation method of a modified soybean-based adhesive, which comprises the following steps of: 1, slowly heating diethylenetriamine and adipic acid to 190 ℃ to perform amidation reaction, and keeping the reaction at 190 ℃ for 6-11 hours after water generated by the reaction is removed to obtain reaction mother liquor; adding epoxy chloropropane into the reaction mother liquor, wherein the molar ratio of the epoxy chloropropane to the diethylenetriamine is 1.05-1.2: 1, continuously stirring and heating to 50-90 ℃, adjusting the viscosity value to 25-100 mPa.s, and stopping reaction; and adjusting the pH value to obtain a modifier, and adding defatted soybean powder into the modifier to obtain the soybean-based adhesive. The solid content of the prepared soybean-based adhesive is adjustable, the viscosity and the coating thickness of the adhesive can be adjusted in use, and the application range is wide.)

1. The preparation method of the modified soybean-based adhesive comprises degreasing soybean flour and blending with water, and is characterized by comprising the following steps:

step 1: mixing a mixture of 1: 1, slowly heating diethylenetriamine and adipic acid in a reaction kettle to 190 ℃ to perform amidation reaction, keeping the reaction at 190 ℃ for 6-11 hours after water generated by the reaction is removed, then cooling to 60-80 ℃, adding water, and stirring to obtain reaction mother liquor;

step 2: adding epoxy chloropropane into the reaction mother liquor, wherein the molar ratio of the epoxy chloropropane to the diethylenetriamine is 1.05-1.2: 1, continuously stirring and heating to 50-90 ℃, adding water for several times to adjust the viscosity of the reaction mother liquor, and stopping the reaction when the viscosity value reaches 25-100 mPa.s;

and step 3: adjusting the pH value to 2.5-3.5 to obtain a concentrated solution with the solid content ranging from 10% to 30%;

and 4, step 4: adding water into the concentrated solution, diluting and stirring the concentrated solution until the solid content ranges from 4% to 16% of the modified solution;

and 5: and adding 30-55 parts of defatted soybean flour into 100 parts of the modification solution, and stirring to obtain the soybean-based adhesive with the solid content ranging from 28% to 45%.

2. The method of claim 1, wherein in step 1, the reaction is maintained at 190 ℃ for 6 hours.

3. The method of claim 1, wherein the cooling temperature in step 1 is 75 ℃.

4. The method of claim 1, wherein in step 3, the pH is 3.

5. The method of claim 1, wherein in step 3, one or more of dilute hydrochloric acid, dilute sulfuric acid, oxalic acid, boric acid, phosphoric acid, and citric acid is used to adjust the pH.

Technical Field

The invention relates to the field of wood adhesives, in particular to a preparation method of a modified soybean-based adhesive with adjustable solid content of the soybean-based adhesive.

Background

The adhesives for the wood industry in China are mainly ' three-aldehyde glue ' (urea-formaldehyde glue, phenol-formaldehyde glue and melamine-formaldehyde glue) ', and the raw materials of the ' three-aldehyde glue ' are all from chemical products such as petroleum and the like, and have limited resources and are not renewable. Moreover, formaldehyde is released in the production and use processes of the 'three-aldehyde glue' product, headache and dizziness can be caused by long-term low-concentration formaldehyde contact, respiratory dysfunction and hepatotoxic lesion can be caused, acute poisoning can be caused by overhigh concentration, and the health of industrial workers and consumers is seriously harmed. In order to deal with formaldehyde hazards and realize effective utilization of biomass resources, reports of manufacturing wood adhesives by using renewable protein resources appear at present.

The soybean-based adhesive is prepared from soybean meal which is a renewable natural plant resource and is used as a raw material and water as a dispersion medium, and is suitable for the requirements of the existing artificial board manufacturing process, has excellent performance and does not contain harmful substances such as formaldehyde, phenol and the like.

The solid content is an important index of the adhesive, directly influences the cost performance of the adhesive, and influences the viscosity and the coating thickness in use until the adhesive performance of the adhesive is influenced. At present, the solid content of a soybean-based adhesive product is not adjustable, so that the viscosity and the coating thickness cannot be adjusted in use, and the application range is small.

Disclosure of Invention

The invention aims to provide a preparation method of a modified soybean-based adhesive with adjustable solid content, which can adjust the viscosity and the coating thickness of the adhesive in use and has wide application range.

The invention provides a preparation method of a modified soybean-based adhesive, which comprises degreasing soybean flour and blending with water, and specifically comprises the following steps:

step 1: mixing a mixture of 1: 1, slowly heating diethylenetriamine and adipic acid in a reaction kettle to 190 ℃ to perform amidation reaction, keeping the reaction at 190 ℃ for 6-11 hours after water generated by the reaction is removed, then cooling to 60-80 ℃, adding water, and stirring to obtain reaction mother liquor;

step 2: adding epoxy chloropropane into the reaction mother liquor, wherein the molar ratio of the epoxy chloropropane to the diethylenetriamine is 1.05-1.2: 1, continuously stirring and heating to 50-90 ℃, adding water for several times to adjust the viscosity of the reaction mother liquor, and stopping the reaction when the viscosity value reaches 25-100 mPa.s;

and step 3: adjusting the pH value to 2.5-3.5 to obtain a concentrated solution with the solid content ranging from 10% to 30%;

and 4, step 4: adding water into the concentrated solution to dilute and stir until the solid content is in the range of 4-16 percent;

and 5: and adding 30-55 parts of defatted soybean powder into 100 parts of the modified solution, and stirring to obtain the soybean-based adhesive with the solid content ranging from 28% to 45%.

Preferably, in step 1, the reaction time is kept at 190 ℃ for 6 h.

Preferably, in step 1, the cooling temperature is 75 ℃.

Preferably, in step 3, the pH is 3.

Preferably, in step 3, one or more of dilute hydrochloric acid, dilute sulfuric acid, oxalic acid, boric acid, phosphoric acid and citric acid is used for adjusting the pH value.

The solid content of the soybean-based adhesive prepared by the invention is adjustable, namely the solid content is as follows: adipic acid: the mol ratio of the epichlorohydrin is 1: 1: 1.05-1.2, preparing a large amount of reaction mother liquor at one time, adding water for adjustment to obtain concentrated solution with the solid content ranging from 10% to 30%, adding water for dilution and stirring according to different solid content requirements to obtain modified solution with the solid content ranging from 4% to 16%, adding a proper amount of defatted soybean powder into the modified solution to finally obtain the soybean-based adhesive with different solid content ranges, wherein the application performance of the soybean-based adhesive with corresponding solid content such as viscosity is optimal. In the presence of diethylenetriamine: adipic acid: the mol ratio of epoxy chloropropane is 1: 1: the solid content of the modified solution prepared under the condition of 1.05-1.2 is adjustable because the modified solution has a large amount of hydrophilic group amino (-NH2), is easy to dissolve in water, and the modified solution after water is added is not denatured, and the amino is an active group and can form a cross-linking structure with a group in the soybean protein so as to increase the water resistance and the strength of the soybean protein adhesive. Besides the advantage of adjustable solid content, the pH value is adjusted to 2.5-3.5 in the preparation process of the adhesive, the viscosity of the adhesive is appropriate, the use requirement is met, and the anticorrosion performance of the adhesive is improved.

The invention has the beneficial effects that:

1. in the presence of a multi-component diethylenetriamine: adipic acid: the mass ratio of the epichlorohydrin is 1: 1: under the condition of 1.05-1.2, the solid content of the prepared soybean-based adhesive can be adjusted, the range can reach 28% -45%, the viscosity and the coating thickness of the adhesive can be adjusted during use, and the application range is wide; meanwhile, the produced soybean-based adhesive with the corresponding solid content has the best application performance.

2. The pH value of the modifying solution is adjusted to 2.5-3.5, so that the corrosion resistance of the final finished product soybean-based adhesive can be improved.

3. The soybean-based adhesive prepared by the invention is green and environment-friendly, free of formaldehyde, and simple in production technology and process.

Detailed Description

The present invention will be further described with reference to the structures or terms used herein. The description is given for the sake of example only, to illustrate how the invention may be implemented, and does not constitute any limitation on the invention.

The polyethylene polyamine in each of the following embodiments may also be one of ethylenediamine, triethylenetetramine or tetraethylenepentamine, and the dibasic acid may also be one of tartaric acid, aspartic acid, succinic acid, malonic acid and itaconic acid.

The soy-based adhesives prepared in the examples described below can be roll coated, knife coated, curtain coated, or sprayed onto wood materials including plywood, blockboard, bamboo plywood, particle board, fiber board, or wood wool board, among others.