Development of PVA Modified Corrugated Paperboard Starch Glue

1 Introduction

In the early 1980s, nearly 100 carton factories in China imported corrugated cardboard production lines from the United States, Japan, Italy, and Taiwan. The adhesive used is generally a starch gum. Starch gum is widely used in the corrugated paper industry at home and abroad because of its advantages of low cost, simple gluing process, fast drying speed, and ability to adapt to high-speed production requirements. However, the original starch gel has the following problems, and the rubber material is prone to precipitation during use, is susceptible to mildew damage during high temperature, and has poor adhesion performance. The above reasons have resulted in the waste of rubber in the production process, the unstable performance of the cardboard, and even much lower than the national standards. In order to enhance its performance, foreign countries developed the modified starch glue in the late 1970s and early 1980s. Among them, modified amylum, ketoaldehyde resin, amine, sodium hypochlorite, sodium stearate, and sodium bisulfite were used to modify starch. Has achieved better results. However, these methods have problems such as complicated gluing process, difficulty in raw material sources, and the like. With the deepening and development of China's reform and opening up, many products require exquisite and reliable packaging, and the packaging industry has become increasingly demanding on the quality of cartons. Therefore, it is of great practical significance to develop a modified starch adhesive that adapts to our national conditions. According to the actual situation of China's chemical raw materials, we use a wide range of polyvinyl alcohol as a modifier, and modify the starch glue under a simple process conditions. The corrugated board produced has stable performance and improved quality.

2 experimental part

2.1 Materials

And reagents polyvinyl alcohol (PVA), industrial grade, degree of hydrolysis: 99%, degree of polymerization: 1700; corn starch, industrial grade; sodium hydroxide (30% solution), industrial grade; borax, industrial grade.

2.2 Experimental methods

In the carton workshop of Nanjing Carton General Plant, water, starch and sodium hydroxide solution were added to the B reactor, stirred, and heated to 35°C as a carrier after gelatinization. Water, starch, PVA, and borax were added to the A reactor and the mixture was used as a main body after stirring. The plastic material in the A-kettle and the carrier in the B-kettle were uniformly mixed and then sent to the rubber roll in the cardboard production workshop. The cardboard produced was sent to the testing department and then tested to the GB5034-85 to determine the adhesiveness. Figure 1 shows a schematic diagram of the production flow of the production test glue and board.

3 Results and Discussion

According to the above process, 18 caulks were produced successively (about 13 tons). The glue does not precipitate or mold. Produce 100,000 square meters of cardboard. The paperboard sampling and testing department of each bottle of gum was used to determine the adhesive fastness. The results are shown in the production test section of Table 1. Table 1 also lists the performance indicators of cardboard produced by the modified starch carton at Nanjing Carton General Plant.

4 Analysis of Adhesion Mechanism

It is necessary to gelatinize some of the starch in advance. If the raw starch is mixed directly with water, it is easy to separate and cannot be glued. However, if all the starch is gelatinized with water, the viscosity of the starch paste is too large and the flowability is poor, and it cannot be used on an assembly line apparatus. Sodium hydroxide is added to the mixture of starch and water. The sodium ions in sodium hydroxide combine with the hydroxyl groups in the starch molecules. The above reaction destroys some of the hydrogen bonds, weakens the intermolecular forces, and lowers the gelatinization temperature. Gelatinization occurs at a lower temperature (35°C) and the gelatinization temperature of corn starch is 62-72°C. Polyvinyl alcohol is the only polyhydroxy polymer that is soluble in water. Excellent film forming and emulsifying properties. The adhesive layer has high strength and good toughness. Its solution has strong adhesion to porous, absorbent surfaces (paper, etc.). The starch and polyvinyl alcohol in the main body are uniformly suspended in a paste consisting of water, borax and carrier. During the limb application, the starch glue can be evenly coated on the paper. Due to the heating and pressure action of the roller and the subsequent drying, the raw starch is gelatinized and the viscosity increases rapidly. Polyvinyl alcohol gels under the effect of temperature and borax, and the strength of the film after drying is greater, thereby improving the adhesive fastness of the cardboard.

5 Conclusion

(1) The use of PVA modified starch glue for corrugated board, easy access to raw materials, the factory can produce without adding any glue equipment, the glue making process is simple and easy to operate.

(2) The modified starch glue does not precipitate, mold, stable quality, easy to use, long service life. The corrugated paperboard made of the same has a fastening fastness of more than 60kg10cm2, which fully complies with national standards.
(3) The application of modified starch glue can improve the quality of corrugated paperboard boxes and prevent the loss of goods, especially export goods, during transport turnover, and has certain economic and social benefits.