Preparation and Modification of PVB-6# Glue

[Abstract] The article introduces the formulation, production methods, product performance, application and improvement methods of PVB-6# glue.
Keywords: PVB-6# glue; formulation: production method; product performance; improved method.
Polyvinyl butyral (abbreviated as PVB) is dissolved in alcohol, and a light yellow viscous glue liquid produced by adding rosin and other modifiers is commonly called PVB-6# glue. It is the largest amount of adhesive used in the cigarette industry. Cigarette paper (cigarette paper), aluminum foil paper (inner packaging paper) and cigarette box packaging paper are produced. With the improvement of the technical level of cigarettes and the improvement of people’s living standards, higher requirements have been placed on cigarette materials: the cork paper should be bright without discoloration, and color printing (even three-dimensional printing) on ​​the cork paper should be easy; aluminum foil paper should not be light off. Powder; decorative packaging box shines. To achieve the above requirements, 6# glue must have strong adhesion, bright film, and no discoloration. The traditional formula can not satisfy the above characteristics.
In actual production, according to different uses, the formula of 6# glue should be adjusted accordingly, that is to say, the base PVB-6# glue should be modified. This article discusses methods and modified methods for improving the quality of glue.
1 Experiment 1.1 Experimental main materials a. alcohol. The quality of alcohol differs greatly. Its water content and odor have a great influence on the quality of the product. The requirements for the quality of alcohol in production are shown in Table 1.
Table 1 Alcohol quality indicators

Item Appearance Odor Ethanol Content Ethanol Content Non-volatile Content Index Colorless, transparent, Odorless ≥ 95% ≤ 0.0030% ≤ 0.0025%

b. Polyvinyl butyral (PVB). PVB is the main raw material of No. 6 glue, and the quality of PVB has a great influence on the technical indexes such as viscosity and adhesion of plastics. See Table 2 for the quality indicators of PVB used in No. 6.
Table 2 Quality Indicators of PVB

Item Viscosity (Coated -1 cup) Butyraldehyde-based content Moisture content Acid value (KOH mg/g) Fineness (20 mesh pass) Transparency index ≥ 45% 43% - 49% ≤ 3.0% ≤ 0.8 100% 75 - 85

Note: PVB Jiaozuo City Group produces.
c. Other modified additives, such as rosin, alcohol-soluble phenolic resin, shellac, castor oil, octadecanol or cetyl alcohol, dibutyl phthalate, etc., generally require 1-2 grade industrial products.
1.2 Process First in the reaction kettle, add alcohol, add PVB to stir at room temperature, heat up and dissolve. After PVB is completely dissolved (called base 6# glue), reduce the temperature in the kettle, according to different purposes. Add the appropriate modifier, mixing and mixing evenly at constant temperature. After sampling and analysis, cool, filter, weigh, pack, and store.
1.3 Basic 6# Glue Main Indicators The basic 6# Glue is tested according to internal company standards. The main technical indicators are shown in Table 3.
Table 3 The main technical indicators of the basic 6# rubber

Project Appearance Viscosity (Coated -1 cup) Solid content Coating Appearance Adhesion (Cottage method)
Index colorless transparent viscous liquid ≥35% 9% smooth and slightly light ≤3

2.1 The key production conditions of the basic 6# glue The production process of the basic 6# glue is relatively simple, it is the dissolution process of PVB in alcohol, but the operation process should pay special attention to: a. PVB must be slowly added with stirring to prevent caking in the kettle; b. PVB must be swelled at room temperature for more than 1h to increase the temperature, otherwise it is easy to form insoluble lumps; c. In the production of base rubber, moisture must not be allowed to enter, and the water content of raw materials must not exceed the standard, otherwise, the rubber in the whole pot will be scrapped.
2.2 Methods to improve the adhesion of the adhesive The base 6# adhesive has poor adhesion. The modification method is to add a more polar resin, but the amount of polar polymer resin that can be dissolved in alcohol is very limited. Through screening, rosin, alcohol-soluble phenolic resin, shellac paint and other substances are better. Their proper amount can significantly increase the adhesion of the glue. When adding these resins should also pay attention to the following 3 points: a. The resin must be crushed first, the particle size is less than 1mm, otherwise the dissolution time is too long; b. The amount of several resins is generally 2% to 5% of the total amount of the glue, and one or two of them may be used; c. When used as an adhesive for aluminum foil coating, a primary or premium product must be used, otherwise darker colors affect the quality of the paper.
2.3 Method of improving the lightness of the glue Adding an oily substance to the glue can improve the brightness of the film. Experiments have proved that castor oil and dibutyl phthalate are more ideal, they are oils and not greasy, have some solubility in alcohol, can significantly improve the film brightness. In addition, higher alcohols (such as octadecanol or cetyl alcohol) have the brightening properties of paraffin wax and have a certain degree of solubility in alcohol. Adding proper amount can not only brighten the film, but also make the film more bright when rubbed. This is what the business wants. It should be pointed out that when these substances are added, it is necessary to control the amount of addition, and adding too much will reduce the adhesion of the glue and affect the drying speed of the glue. The general amount is 1%-3%.
2.4 Conditions affecting the quality of cigarette paper products Whether using 6# glue to produce tipping paper, aluminum foil or outer packaging paper, it is necessary to add appropriate pigments or fillers in the rubber compound, and the ratio of the glue used in the glue and fine grinding Degree of influence on the quality of paper crystal production. Such as brown yellow cigarette holder tipping paper production requires the appropriate amount of iron yellow, iron red and high-quality talcum powder and 6 # glue together before grinding can be used.
3. Concluding remarks PVB-6# glue has strong specificity, and the modification method still needs more discussion in actual production. Only in this way can we continuously improve product quality and expand product application range.