CN101191038A - Preparation method of papermaking black liquor adhesive - Google Patents

Abstract

The invention discloses a preparation method of a papermaking black liquor adhesive. The adhesive is prepared by using ethylene urea, melamine or polyvinyl alcohol as a formaldehyde scavenger, adding urea, flour and urea-formaldehyde resin to react. On the one hand, the invention can reduce the formaldehyde emission of the board and improve its water resistance; on the other hand, it can find an effective way for the comprehensive utilization of the papermaking black liquor or the lignin extracted from the papermaking black liquor.

Description

Preparation method of papermaking black liquor adhesive

technical field

The invention relates to a preparation method of an environment-friendly papermaking black liquor adhesive, in particular to a production method of a composite papermaking black liquor adhesive.

Background technique

my country is a country of Shaolin, and there is a big contradiction between the supply and demand of timber. An important way to solve this contradiction is to vigorously develop the production and utilization of composite panels centered on wood-based panels. Using urea-formaldehyde resin adhesive to produce 1 cubic meter of particleboard can replace 3.1 cubic meters of log boards; and using urea-formaldehyde resin adhesive to produce 1 ton of fiberboard can replace 5.6 cubic meters of log boards. That is to say, adhesives are of great significance to improving the utilization rate of wood; at the same time, the consumption of adhesives in the wood industry is also huge. A large amount of adhesive must be used. For example: the production of 10,000 cubic meters of plywood requires 1,000 tons of adhesive.

It can be seen that a large amount of adhesive is consumed in the production of composite boards, and urea-formaldehyde resin adhesive is the most used in these adhesives. It has better bonding performance, and its adhesive strength is higher than that of animal and vegetable adhesives. It has good light resistance and is suitable for the production of glue for wood, plywood, laminated boards and bamboo wood products. More importantly, it is widely used because of its relatively low price. And these composite plate products are widely used in places such as people's long-term residence and life, homes and offices. However, there is a certain amount of free formaldehyde in these adhesives or composite board products. For example, the content of free formaldehyde in urea-formaldehyde resin adhesives is as high as 3-5%, because it emits toxic gas-formaldehyde during production, processing and use, causing serious pollution. Damage to people's health should be greatly restricted in use. However, it is still unable to effectively limit its use, and it has developed into an uncontrollable situation. Therefore, the research, development, application and promotion of adhesives for composite panels with low formaldehyde content or composite panels without free formaldehyde have become a top priority and appear to be very necessary. The present invention has developed a low-cost composite sheet adhesive with low free formaldehyde content and meets environmental protection requirements, and makes it maintain various excellent properties of urea-formaldehyde resin adhesives, reduce its production cost, and make it practical for all composite sheet processing enterprises to fully bear. type adhesive.

In December 2001, my country formulated ten mandatory national standards such as GB18580-2001 "Formaldehyde Release Limits of Wood-based Panels and Their Products for Interior Decoration Materials", GB18583-2001 "Limits of Hazardous Substances in Adhesives for Interior Decoration Materials", etc., since 2002 Mandatory from July 1st. The new standard has a very low limit on the release of free formaldehyde, but the wood-based panels currently produced in my country are still difficult to meet the requirements of the new national standard. This is mainly due to the use of urea-formaldehyde resin adhesives with high free formaldehyde content, which is also a major technology that is currently difficult to solve problem. Moreover, the new standard's limit on the release of free formaldehyde has not yet met the basic requirements for protecting human health, and there is a possibility or requirement for continued reduction.

Contents of the invention

The purpose of the present invention is to provide an adhesive that can reduce the formaldehyde emission of the board and improve its water resistance, which is produced by using the papermaking black liquor.

Above-mentioned papermaking black liquor adhesive is to make by following steps:

1. Add 0.15 parts of polycondensation agent to a 500ml container, add 1.56 parts of papermaking black liquor when the temperature rises to 40°C-50°C, add 0.16 parts of catalyst while stirring, and react for 30 minutes when the temperature of the solution is kept at 45°C-55°C. Add 0.50 parts of 36% formaldehyde to the solution, keep the temperature of the solution at 45°C to 55°C for 30 minutes, then raise the temperature of the solution to 80°C to 85°C within 30 minutes, then add 0.30 parts of 36% formaldehyde to 0.40 parts, stirred and reacted at 80℃～85℃ for 120 minutes, after the reaction, the temperature of the solution was raised to 85℃～95℃ within 30 minutes, the solution was kept at this temperature for 10 minutes, and then the solution was cooled to 80℃～ within 20 minutes 85°C, keep the temperature for 40 minutes, then add 0.50 to 0.80 parts of papermaking black liquor, keep the temperature of the solution at 80°C to 85°C and stir for 30 minutes to prepare raw gum;

2. Add 0.06 to 0.10 parts of formaldehyde trapping agent to 1 part of raw gum prepared in step 1, and stir for 30 minutes while the temperature of the solution is kept at 80°C to 85°C;

3. Add 0.05 to 0.10 parts of flour to the glue prepared in step 2, stir and react at room temperature for 30 minutes to prepare papermaking black liquor adhesive.

The polycondensation agent is phenol, the catalyst is sodium hydroxide, and the formaldehyde trapping agent is urea, ethylene urea or melamine.

On the one hand, the above-mentioned papermaking black liquor adhesive can reduce the formaldehyde emission of the board and improve its water resistance; on the other hand, it can find an effective way for the comprehensive utilization of papermaking black liquor or lignin extracted from papermaking black liquor. At present, the pollution of papermaking black liquor to the environment has surpassed all pollution, and has gradually developed into the largest pollution source, especially the damage to water quality caused by papermaking black liquor is catastrophic. This research project successfully used papermaking black liquor or lignin extracted from papermaking black liquor as an adhesive for making composite boards, and has formed new technologies, new processes, new formulas and methods for the production of low-cost and environmentally friendly adhesives for composite boards The new method has changed the current production status and should have at least two advantages: first, it can produce adhesives for composite panels with low free formaldehyde content, and provide composite panels without free formaldehyde content for the interior decoration industry to improve the indoor environment. Second, the use of paper-making black liquor lignin to produce composite boards and adhesives not only provides cheap and widely sourced raw materials for this behavior, but also solves the environmental pollution problem of paper-making black liquor in paper-making enterprises. The comprehensive utilization of the lignin extracted from the liquid has found an effective way.

The successful research of low-cost and environment-friendly composite panel adhesive provides basic conditions for composite panel manufacturing and interior decoration industry. The enforcement of new national standards and the continuous increase of people's environmental awareness provide opportunities for the promotion and application of low-cost environmentally friendly composite sheet adhesives. Therefore, the promotion and application prospect of this project is very broad, and it will also produce huge economic and social benefits. Moreover, the project has the characteristics of small investment, quick results, and adaptability to the production organization of small and medium-sized enterprises. The current production equipment for producing urea-formaldehyde resin or phenolic resin adhesive can organize production without changing.

The formation principle of phenolic resin adhesive is: in the presence of alkali, the para-position of the phenolic hydroxyl group in the phenol molecule and the two ortho-position hydrogens react with formaldehyde to generate various isomers of hydroxymethylphenol.

The generated hydroxymethylphenol isomers, in addition to continuing to react with phenol, can also react with formaldehyde to generate polyhydroxymethylphenols.

Various hydroxymethylphenols can react with each other, and can also react with phenols and aldehydes to form initial phenolic resins, and then undergo further polycondensation reactions to obtain the final form of phenolic resins with a network-like molecular structure.

The main components in papermaking black liquor are lignin and alkali, and the main structure of lignin is currently considered to be mainly phenylpropane, and there are only three basic structures (non-condensed structures), namely:

Guaiac wood-based structure syringyl-based structure para-hydroxyl-based structure

There are more hydroxyl groups in the lignin structure, which exist in two forms: alcoholic hydroxyl groups and phenolic hydroxyl groups. In the presence of alkali, lignin has a reaction with formaldehyde to form a methylol group, which includes two aspects. One is that the methylol reaction can occur on the vacancy on the lignin aromatic ring, and the other is that the side bond of the aromatic ring can also react. A hydroxymethylation reaction occurs. Therefore, theoretically speaking, the free formaldehyde content of the composite sheet adhesive made from papermaking black liquor is very low or free, and the water resistance should be very good. At the same time, this basic structure and reaction also create basic conditions for the papermaking black liquor to be used to prepare papermaking black liquor adhesives and to make composite boards.

Flour contains polyhydroxyl groups, which can form acetals with free formaldehyde, thereby preventing free formaldehyde from being released into the air and reducing pollution. At the same time, the papermaking black liquor adhesive reacts with the aldehyde group on the _C6 of the glucose unit in the molecular structure of flour or potato starch slag to form hemiacetal and acetal during the hot-press curing stage of sheet production, forming a cross-linked body structure , so it can increase the adhesive strength and water resistance of the glue. In addition, it can also be added to the glue as a filler, and its filling effect can reduce the volume shrinkage of the glue layer, thereby reducing the pressure caused by the same volume shrinkage. And it can increase the solid content of the product, remove the vacuum dehydration operation in the original process, and reduce the consumption of raw materials and operating costs at the same time.

Detailed ways

Example 1

1. Add 15g of phenol into a 500ml container, add 156g of papermaking black liquor when the temperature rises to 40°C, add 16g of sodium hydroxide under stirring, keep the temperature of the solution at 45°C for 30 minutes, and add 36% formaldehyde to the solution 50g, the temperature of the solution was kept at 45°C for 30 minutes, then the solution was heated to 80°C within 30 minutes, then 30g of 36% formaldehyde was added, and the reaction was stirred at 80°C for 120 minutes. After the reaction, within 30 minutes, the The temperature of the solution is raised to 85°C, the solution is maintained at this temperature for 10 minutes, then the solution is cooled to 80°C within 20 minutes, and the temperature is maintained for 40 minutes, and 50g of papermaking black liquor is added after 40 minutes, and the temperature of the solution is maintained at 80°C and stirred for reaction Prepare raw gum in 30 minutes;

2. Add 6 g of urea to 1 part of raw gum prepared in step 1, and stir and react for 30 minutes while the temperature of the solution is kept at 80° C.;

3. Add 5 g of flour to the glue prepared in step 2, stir and react at room temperature for 30 minutes to prepare papermaking black liquor adhesive.

Example 2

1. Add 15g of phenol into a 500ml container, add 156g of papermaking black liquor when the temperature rises to 450°C, add 16g of sodium hydroxide under stirring, keep the temperature of the solution at 55°C for 30 minutes, and add 36% formaldehyde into the solution 50g, the temperature of the solution is kept at 55°C for 30 minutes, then the solution is heated to 85°C within 30 minutes, the solution is kept at this temperature for 30 minutes, then 40g of 36% formaldehyde is added, and the reaction is stirred at 85°C for 120 minutes After the reaction, the temperature of the solution was raised to 95°C within 30 minutes, and the solution was maintained at this temperature for 10 minutes, then the solution was cooled to 85°C within 20 minutes, and the temperature was maintained for 40 minutes, and 80g of papermaking black liquor was added after 40 minutes, and the solution was The temperature was kept at 85°C and the reaction was stirred for 30 minutes to obtain the raw gum;

2. Add 10 g of ethylene urea to 1 part of raw gum prepared in step 1, and stir and react for 30 minutes while the temperature of the solution is kept at 85°C;

3. Add 10 g of flour to the adhesive prepared in step 2, and stir and react at room temperature for 30 minutes to prepare the papermaking black liquor adhesive.

Example 3

1. Add 15g of phenol into a 500ml container, add 156g of papermaking black liquor when the temperature rises to 40°C, add 16g of sodium hydroxide under stirring, keep the temperature of the solution at 45°C for 30 minutes, and add 36% formaldehyde to the solution 50g, the temperature of the solution is kept at 45°C for 30 minutes, then the solution is heated to 80°C within 30 minutes, the solution is kept at this temperature for 30 minutes, then 40g of 36% formaldehyde is added, and the reaction is stirred at 80°C for 120 minutes After the reaction, the temperature of the solution was raised to 85°C within 30 minutes, and the solution was maintained at this temperature for 10 minutes, then the solution was cooled to 80°C within 20 minutes, and the temperature was maintained for 40 minutes, then 80g of papermaking black liquor was added, and the temperature of the solution was maintained Stir and react at 80°C for 30 minutes to prepare raw gum;

2. Add 10 g of melamine to 1 part of raw gum prepared in step 1, and stir and react for 30 minutes while the temperature of the solution is kept at 80° C.;

3. Add 10 g of flour to the adhesive prepared in step 2, and stir and react at room temperature for 30 minutes to prepare the papermaking black liquor adhesive.

Papermaking black liquor adhesive analysis results:

Claims (5)

1. the preparation method of a paper-making black liquor adhesive, it is characterized in that: it is to be made by following steps,

One, in the 500ml container, add 0.15 part of polycondensation agent, add 1.56 parts of black liquids when being warmed up to 40 ℃～50 ℃, stir and add 0.16 part of catalyzer down, reaction was 30 minutes when the temperature of solution remained on 45 ℃～55 ℃, 0.50 part in the formaldehyde of adding 36% in solution, reaction was 30 minutes when the temperature of solution remained on 45 ℃～55 ℃, in 30 minutes, solution is warmed up to 80 ℃～85 ℃ then, add 0.30 part～0.40 part in 36% formaldehyde again, stirring reaction is 120 minutes in the time of 80 ℃～85 ℃, the reaction back was warmed up to 85 ℃～95 ℃ with solution in 30 minutes, solution kept this temperature 10 minutes, in 20 minutes solution was cooled to 80 ℃～85 ℃ then, kept this temperature 40 minutes, add 0.50 part～0.80 part black liquid again, the temperature of solution remains on 80 ℃～85 ℃ stirring reactions and made virgin rubber in 30 minutes;

Two, add 0.06 part～0.10 part of methanal trapping agent in 1 part of virgin rubber that step 1 makes, stirring reaction was 30 minutes when the temperature of solution remained on 80 ℃～85 ℃;

Three, add 0.05 part～0.10 part in flour in the jelly that step 2 is made again, stirring reaction made paper-making black liquor adhesive in 30 minutes under the room temperature.

2. the preparation method of paper-making black liquor adhesive according to claim 1, it is characterized in that: above-mentioned formaldehyde-trapping agent is a urea.

3. the preparation method of paper-making black liquor adhesive according to claim 1, it is characterized in that: above-mentioned formaldehyde-trapping agent is the ethylene group urea.

4. the preparation method of paper-making black liquor adhesive according to claim 1, it is characterized in that: above-mentioned formaldehyde-trapping agent is person's trimeric cyanamide.

5. the preparation method of paper-making black liquor adhesive according to claim 1, it is characterized in that: described polycondensation agent is a phenol, catalyzer is a sodium hydroxide.