DISPERSION ADHESIVES FOR THE PAPER AND PRINTING INDUSTRY
The use of dispersion adhesives in the paper industry is one of the conventional ways of application. Their advantages being that they have excellent adhesion properties within a wide range of applications, the immediate readiness of use, the simplicity of use, the high resistance of glued connection against ageing, temperatures and oils and its excellent workability.
Duvilax that is designed for papermaking is a white liquid with low fluidity that gives off a characteristic odor. They are non-explosive, non-flammable and non-toxic. The film formed by the drying of the adhesive is transparent, yellowish or slightly turbid. It is contiguous, depending on the type -there is a different elasticity and smoothness.
From a chemical point of view, Duvilax glues are aqueous homopolymeric polyvinyl acetate dispersions,treated with a plasticizer and other components or aqueous copolymer dispersions of vinyl acetate with other comonomers, which may be treated with various additives, e.g. plasticizers, fillers, starch, defoamers, biocides etc. The emulsion system consists of a nonionic emulsifier and polyvinyl alcohol that is used as a protective colloid.
In the process of hardening/drying, there is no chemical reaction or change. This is the physical process in which glued material - paper, cardboard, etc. removes water gradually from the adhesive, forming a continuous film on its surface. It is not necessary to add any initiator, to dilute or to heat them.
Corrugated cardboard laminating
Smooth cardboard laminating
Production of smooth cardboard
Production of paper protecting corners
Production of paper tubes
Production of paper honeycombs
Gluing of paper / cardboard boxes
Duvilax dispersions in paper industry are used for the production of smooth, lightweight and corrugated paperboard, for paper adhesie laminating, for the production of paper tubes, honeycombs, protective corners, books, and various paper packing materials. Duvilax significantly influences the quality of the resulting product. It delivers to paper product consistency, strength, hardness, flexibility and durability. Dispersion adhesives are used to bond directly, without further processing or adding other ingredients.
Duvilax adhesives in polygraphy - printing industry - are used in book production - they are used for bonding book blocks into harcover, sticking book blocks, sticking textile tabs, gluing hardboard with decorative foils, textiles etc.
Requirements for the product's technical parameters
The technical parameters of dispersion adhesives within the paper industry are defined according to the requirements of the individual applications and the respective specific stand equipment in individual consumer plants. With the requirement to adapt the technical properties of the material, it is possible to directly define the required quality based on empirical tests.
The paper glue is mostly applied by rotating rollers, cylinders. Occasionally, it is used as a sieve, spraying through nozzles or brushes. Material flowability - the viscosity is determined by the coating device, with emphasis being placed on a sufficient and uniformed bonding of the binder to the bonded layers. Depending on the type of machine and the quality of the paper, the viscosity may be low or moderately high. By special requirements, we produce binders with high viscosities (up to 35,000 mPa.s, Brookfield).
Dry matter content adjustments
Dry matter indicates the solids content of the dispersion. The solid content of the dispersion binders is about 50%. However, it is not the exception of dry matter moving at the level of 30% and vice versa about 60%. The water content of the dispersion is directly proportional to the drying time and the wetting rate of the glued paper as well as to the surface deposition of the active ingredient of the adhesive, thereby affecting the adhesive rate.
Treatment of the film´s properties
Vinyl acetate dispersions whose film is soft, flexible and elastic have proven to be the most suitable in paper technology. Properties in vinyl acetate dispersions are influenced by the addition of plasticizers, of homopolymeric types or by different ingredients. In copolymeric dispersions, the plasticizer function takes up the copolymer component in the polymer chain. The degree of elasticity and hardness of the film depends on the type of plasticizer used and the proportion.
Dispersible binders made from vinyl acetate are naturally slightly acidic. Their pH ranges from 3 to 6, although this property can be influenced. The pH can be increased to 9 in agreement with the purchaser.
Duvilaxes can be applied in virtually all manner of use, e.g. rollers, small rollers, spreading machines and spray guns. It can be applied unilaterally or bilaterally depending on the type of application. It is necessary to adjust the viscosity of the adhesive to the application method.
Machinery and working tools cleaning
The machinery and tools are cleaned with lukewarm water whilst the adhesive is still damp. In the case of drying, it is advisable to leave the unclean surface damp, covered with a wet cloth for around 30 to 60 minutes or until the dried film becomes dull and has softened. Then the adhesive layer is removed mechanically.