Paper Coating Preparation Process by Ginhong Mixer
When we write on a paper, we can observe that different papers have different textures, colors and overall physical properties. Some papers are easy to write on, while others are difficult to write into. These paper properties are solely attributed to its surface finish, which is imparted by the formulation of its coating.
Paper coating gives the paper its adhesion, color, wettability, corrosion resistance and wear resistance. It may also add a completely new property to the paper, such as magnetic response or electrical conductivity.
Important Ingredients to Consider in Paper Coating Process Mixing
A Paper Coating mixture is composed of three essential ingredients: colloidal particles, dissolved polymers such as pigments in water and an adhesive or binder. A coating layer of approximately 10 g/m^2 is usually applied on the base paper where the excess is removed by a steel blade.
Papers may be matte or gloss, natural or bright white color. The coating compounds are mixed according to precise recipes in mixing tanks.
- The main color pigment is Calcium Carbonate, which makes the paper surface white.
- The coating solution also contains Talcum Powder, for paper smoothness.
- Binders can be natural starches or purely synthetic compounds, such as latex. The binder is responsible for holding the pigment particles to each other and to the paper, to fill voids and to affect the viscosity of the mixture.
- Silica is added for applications of good water absorption rate.
- Finally, resins control ink absorption rate.
Clay or pigment suppliers usually deliver these ingredients in tanks containing slurries with 60% solids. These are already prepared prior to mixing. Proper mixing of paper coating ingredients is detrimental in making good paper coats and finish, thus a predetermined type of mixer, its speed, number of agitators and number of blades and the manner of how it would be mixed are all important aspects in making a homogenous mix.
The process of making paper coats can be summarized below:
- First, the slurry is diluted up to its desired fluidity in the storage tank.
- Preparation of the binder will follow prior to mixing with the diluted slurry.
- Additives such as waxes and coloring will be added.
- The finished coating may be passed through a filter to eliminate agglomerates or impurities
- The coating is then applied to the paper or board by a lot of methods
The Problem of Conventional Coating Mixer Machine
The following problems may occur in using conventional Paper Coating Mixers:
- Presence of undissolved substances or agglomerates and impurities due to lack of mixing power.
- Unwanted voids may be created within the slurry.
- Strained or filtered agglomerates reduces yield output, increased wastes, added maintenance and cost.
The Solution of Paper Coating Manufacturing
- Ginhong’s powerful mixers solve Paper Coating Mixing problems through the following solutions:Mixers blades are made strong, having a triangular cross section, which presents a wide profile surface area for efficient mixing action. This ensures that the agglomerates are thoroughly mixed and homogenized.
- Ginhong’s Planetary Mixer blades, in particular, can have two types of mixing movements: revolving on a vertical axis at high speed and at the same time, this vertical axis rotates around the center of the bowl at a relatively lower speed.
- Additives including binders and adhesives rolls over the vessel from top to bottom and back to top repeatedly. When the products are completely mixed, the heat from the jacket is quickly transferred to every part through the inside wall.
- Slow and high forces mixing goes repeatedly until the mixture is circulated inside the vessel and mixed, dispersed, kneaded and homogenized evenly.
Advantages of Ginhong Mixers
Eliminates Flow Isolation
- Flow isolation is prevented because of the wider area of mixing.
Elimination of voids
- Ginhong processes mixing applications under vacuum, which is beneficial for certain adhesives and sealants to develop higher densities and achieve better tensile properties as a result of improved shearing and contact of the different components.
- Ginhong manufactures a wide variety of mixers with a great range of viscosities and applications. Their extensive range of pumps and process systems are designed to withstand extremities when delivering efficient metering, processing and analyzing.
Prevents Material Bridging
- Material bridging and roll-back are prevented by distributing the product evenly.
- Prevents microbial growth in the mixture.
Recommended Ginhong Mixers
Mixer selection is based on a number of factors, including viscosity profile, shear requirement, order of addition and throughput. Coating plant can benefit a lot from optimal mixer.
Ginhong has designed a series of mixers for paper coating manufacturing such as the following:
- Equipped with two or more independently driven agitators
- Deliver both high-shear agitation and laminar bulk flow within a wide viscosity range: from water-like to several hundred thousand centipoise.
- Feature two or more blades that rotate on their respective axes while revolving around the mixing vessel.
- Can be used as circulation system to accelerate the dispersion process
- Produce an agglomerate-free slurry in a fraction of the time taken by agitation alone
Ginhong Recommendable Mixers:
Ginhong Vacuum planetary mixing machinery for sealants and adhesives Video: