Corrugated cardboard box knowledge collection - Bonding and problems (1)

Corrugated board adhesive and its problems

A corrugated board production line starch adhesive formula and process

The single-faced corrugating machine and corrugated board production line is still based on the two-step method currently used to produce finished product starch adhesive, and the raw material formulation, proportion of materials and production process are appropriately improved. The specific raw material used, the ratio and the manufacturing method are as follows.
Use raw materials and recipes:

(a) Starch (wheat starch, potato starch or potato starch):

In the production and use of the production line starch adhesive, different starches are used, and the adhesive has different transparency, adhesive strength, viscosity, gelatinization temperature, and the like. As long as we have a good understanding of the properties of various types of starch and the role of other chemical raw materials in the production of adhesives, a reasonable adjustment formula can be used to make an ideal adhesive. Under the same conditions, in order to increase the speed, wheat starch and tapioca starch with low gelatinization temperature can be selected; in order to improve the bonding strength, tapioca starch and potato starch with strong adhesion can be selected. For different starch physicochemical indexes and relevant data, please refer to the previous chapter “Adhesives for raw materials used in single unit (preparation of raw and auxiliary materials) and the production process”. The amount of starch used in raw materials can be changed as appropriate according to the specific requirements of the binder. :

1. Single-faced corrugated board production requires less adhesives, and the amount of starch is: 150-170kg/ton.
2. In the production of three-layer corrugated board, the single-sided corrugated paperboard is compounded with the surface paper, and the adhesive requirement is slightly higher. The amount of starch is: 170-200kg/ton of glue.
3, five-story, seven-layer corrugated board production and corrugated paper composite. The requirements for adhesives are relatively high. The amount of starch used is: 200-300 kg/ton of glue.

(b) Automatic desiccant (abbreviated as desiccant):

Automatic line desiccant in the adhesive production process, as long as the amount of appropriate, not only to speed up the adhesive film speed, shorten the carton drying time, but also to improve the cardboard drying speed, hardness, bond strength of about 20%, thickness increase 0.1- 1mm, etc.; with 5kg per ton of glue, can reduce the amount of starch about 20% or reduce the weight of corrugated board paper 10-20g/m2, the performance indicators are better than the national export standards. The amount of desiccant for the automatic line is less than 3kg per ton of glue in the adhesive. It should not be effective, and the amount of glue per ton is higher than 10kg, and it is easy to produce cardboard brittleness. So we must strictly control the proportion of placement. The normal dosage standard is 5-8kg/ton glue.

(3) Pasting agents:

Industrial caustic soda (NaOH, this technology requires more than 96% of the content), the amount of caustic soda to be added to the starch liquid, the carrier body is mixed and stirred evenly, the viscosity of the adhesive is adjusted. Under the same conditions, the amount of caustic soda is large, the viscosity is high, and the binder does not produce the phenomenon of sedimentation and stratification during storage; the amount of caustic soda is small and the viscosity is low. The amount of caustic soda should be observed from the actual, adjusted according to the viscosity requirements.

(d) Crosslinking agent:

The binder is added with borax or boric acid, which can make short-chain starch with its hydroxyl or hydroxyl and boron atoms to form a complex, through these irregular cross-links, forming a network structure, with cross-linked thickening effect, is conducive to Improve the initial viscosity and speed up the drying, but also play a role in anti-corrosion and anti-seepage. The amount of borax is adjusted according to the corrugated paper and face paper used in the production of corrugated board. The quality of the paper is poor, and the amount of borax is appropriately increased. The quality of the paper, especially the imported sizing paper, may not be used or the amount of borax may be appropriately reduced.

(five) water resistance enhancer

Water resistance enhancer is an additive used in the production of water-resistant paper products such as coated paper, white paperboard, offset paper, boxboard, etc. It is added to papermaking pulp or carton starch adhesive to improve the wet and dry strength of paper and carton, and water resistance. Sex, prevent paper from falling off, etc.; use 5-10kg per ton of glue, do not open the glue in cardboard at normal temperature for 12-72 hours, and the corrugated will not be deformed; directly add the water-resistant enhancer to the slurry or starch gum, stirring 20 It can be used in minutes. Under the condition of better than the original performance index, it can reduce the amount of starch and the weight of paper used in corrugated board.

Formula and production process: (Unit: kg)

Reference Formulation Raw Material Proportioning for Production Line 1:3.5 Starch : Finished Glue 1:4 Starch : Finished Glue 1:5 Starch : Finished Glue 1:6 Starch : Finished Glue 1:7 Starch : Finished Glue
Carrier Water 200 370 200 200 220 310 350
Starch 25 50 25 25 20 30 38
Automatic line desiccant 4-6 6-8 4-5 4-5 4-5 5-7 5-7
Caustic soda 4-5.5 9-10 5-6.5 5.5-7 2-4 5-6 5-5.5
Body Water 400 550 400 400 350 550 550
Starch 225 250 175 125 130 150 125
Borax 2.5-4 3-5 2.5-4 2.8-4 2.5-4 3-5 4-6

Process flow one:
Carrier (water + starch + automatic drying agent + caustic soda) + body (water + starch + borax)
1. Add the raw materials on the kettle to the stirred tank in order and react for 20-30 minutes.
2. Add the raw material of the next kettle sequentially to the stirred tank and stir for 10-20 minutes.
3. Slowly add the gel on the kettle to the next kettle and stir for 20-40 minutes.

Process II:

According to the special circumstances of some enterprises, in the absence of the main body and carrier production equipment, an agitator can be used for production. According to the formula in the above table, the carrier is processed first in the kettle in order, and then the moisture in the body is divided into two parts; the water and starch with the same weight as the starch are first taken out, and the borax is mixed evenly, and the remaining water is added into the reaction kettle and stirred uniformly. After that, the standby mixture was added to the reactor and stirred for thirty minutes.

Precautions:

1. After adding automatic desiccant, the viscosity will be properly reduced. During the production process, attention should be paid to adjusting the amount of caustic soda. The caustic soda is used to control the viscosity. The amount of caustic soda is increased by using too much glue, and the amount of caustic soda is too thick to reduce the amount of caustic soda.

2. The viscosity control of single-sided machine and three-layer line is about 20-50 seconds.

3, 5 and 7 layers of raw rubber when using the viscosity control: 50-100 seconds, special circumstances, according to the requirements to adjust the viscosity of the adhesive.

4, in the three-layer, five-story automatic production of corrugated cardboard, such as the phenomenon of degumming and cardboard 1-2cm on both sides of the bond is not strong, please check 1 sizing amount is too small; 2 adhesive viscosity is too low; 3 composite Both sides of the roller are too hot.

5, the production companies can also be used according to the original production line rayon process to add a special automatic desiccant raw rubber, in the raw rubber production process, the raw rubber dedicated desiccant before adding caustic soda directly into the carrier, stirring for 10-20 minutes, then Then according to the original process can be produced. The raw rubber special desiccant is acidic. When the rubber is produced, the amount of caustic soda in the raw rubber process formula should be properly increased. The ton of raw starch is about 0.5 kg of caustic soda per ton of raw starch.

(to be continued)