When recycling post-consumer paper, stickies are tacky substances contained in the
paper pulp
Pulp is a Lignocellulosic biomass, lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, Paper recycling, waste paper, or cotton paper, rags. Mixed with water and other chemica ...
and process water systems of
paper machine
A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry
to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machin ...
s. Stickies have the potential to contaminate the components either within or around the equipment necessary in the
Stages of Manufacturing that a
Paper Mill follows in its
Developed Process, but would have otherwise excluded it in its routine cleaning and maintenance procedures.
Contamination
Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc.
Types of contamination
...
s of
paper
Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distrib ...
that are classified as tacky are also called stickies. The main sources for stickies are
recycled paper
The recycling of paper is the process by which waste paper is turned into new paper products. It has a number of important benefits: It saves waste paper from occupying homes of people and producing methane as it breaks down. Because paper fib ...
, waxes, and soft adhesives.
Composition
Stickies are an indefinite mixture of
organic compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...
s, with the main part being different
ester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides a ...
s. The components might stem from:
*Printing
ink
Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker ...
s
*Coating binders (synthetic
latex
Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latexes are found in nature, but synthetic latexes are common as well.
In nature, latex is found as a milky fluid found in 10% of all flowering plants (angiosperms ...
)
*
Waxes
Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to give low ...
*
Hot melt adhesive
Hot-melt adhesive (HMA), also known as hot glue, is a form of thermoplastic adhesive that is commonly sold as solid cylindrical sticks of various diameters designed to be applied using a hot glue gun. The gun uses a continuous-duty heating elem ...
and unsupported
pressure-sensitive adhesive
Pressure-sensitive adhesive (PSA, self-adhesive, self-stick adhesive) is a type of nonreactive adhesive which forms a bond when pressure is applied to bond the adhesive with a surface. No solvent, water, or heat is needed to activate the adhesiv ...
s
*
Plastics
*
Wet strength The wet strength of paper and paperboard is a measure of how well the web of fibers holding the paper together can resist a force of rupture when the paper is wet. Wet strength is routinely expressed as the ratio of wet to dry tensile force at brea ...
resin
In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. Resins are usually mixtures of organic compounds. This article focuses on n ...
s
*
Pitch
*
Papermaking additives
Properties
Stickies that pass through a slotted plate screen of 0.10 - 0.15 mm are called ''micro stickies''. Micro stickies can be finely dispersed (100
µm - 100
nm), colloidal (100 - 10 nm) or molecularly dissolved (< 10 nm). Macro stickies are those which are retained as screening residue. The reason for this classification is that macro stickies are easy to remove from the
deinked pulp
Pulp is a lignocellulosic fibrous material prepared by chemically or mechanically separating cellulose fibers from wood, fiber crops, waste paper, or rags. Mixed with water and other chemical or plant-based additives, pulp is the major raw ma ...
during the
deinking
Deinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp.
The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical ac ...
process by means of filtration. Micro stickies are transported with the pulp to the
paper machine
A paper machine (or paper-making machine) is an industrial machine which is used in the pulp and paper industry
to create paper in large quantities at high speed. Modern paper-making machines are based on the principles of the Fourdrinier Machin ...
and might
agglomerate and cause problematic
deposits
A deposit account is a bank account maintained by a financial institution in which a customer can deposit and withdraw money. Deposit accounts can be savings accounts, current accounts or any of several other types of accounts explained below.
...
there.
Stickies often have
thermoplastic
A thermoplastic, or thermosoft plastic, is any plastic polymer material that becomes pliable or moldable at a certain elevated temperature and solidifies upon cooling.
Most thermoplastics have a high molecular weight. The polymer chains associate ...
properties.
Chemical-physical alterations like
pH,
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer.
Thermometers are calibrated in various Conversion of units of temperature, temp ...
and
charge
Charge or charged may refer to:
Arts, entertainment, and media Films
* '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary
Music
* ''Charge'' (David Ford album)
* ''Charge'' (Machel Montano album)
* ''Charge!!'', an album by The Aqu ...
changes might cause colloidal destabilization and
agglomeration
Agglomeration may refer to:
* Urban agglomeration, in standard English
* Megalopolis, in Chinese English, as defined in China's ''Standard for basic terminology of urban planning'' (GB/T 50280—98). Also known as " city cluster".
* Economies of ag ...
of micro stickies.
Stickies control
Several control methods are used:
*Alteration of the physical properties, like using recycling-friendly paper coatings
*Avoidance of troublesome components that cause stickies
*Removal by more effective
deinking
Deinking is the industrial process of removing printing ink from paperfibers of recycled paper to make deinked pulp.
The key in the deinking process is the ability to detach ink from the fibers. This is achieved by a combination of mechanical ac ...
processes, like improved screening, cleaning, washing and flotation
*Passivation with process additives like
fixation agents
*Prevention by washing wires or protecting equipment parts with chemicals.
*Measuring stickies using TAPPI method T274 and T277
References
{{Paper
Papermaking
Paper recycling