for Adhesive Tapes and other Products By Shrikant Athavale Prathith Consultants Pune MS. India
The release coatings are alsocalled as Abhesive
The coating that is used to prevent or greatly decrease adhesion , istermed as AbhesiveThe coated abhesive , creates a surface that discourages adhesion.Abhesive materials are also often referred to as mold-release agents,non-stick surface coatings, parting agents, or antistick agents.Abhesion is exactly the opposite of adhesion, and the requirements fora good abhesiveThe applications for abhesives are nearly as numerous and ascommercially important as they are for adhesives.The most recognizable abhesives are used as mold release surfacesand as liners for pressure sensitive tapes and labels.
A variety of materials and processes have beendeveloped to provide surfaces that function asabhesives.However, the main purpose of this review will be toexplain the material and surface science fundamentalsrequired for an abhesive to function.
MechanismIn order to understand how abhesives work,Let us understand the mechanism of adhesion and the factors that affect it.Adhesion occurs through a:mechanical interlocking,interdiffusion,adsorption (surface reaction),and electrostatic attraction.adhesion depends onthe surface topology,surface tension and energy,wetting, andthermodynamic work of adhesion.
Therefore, surface treatment is required to enhance adhesion .This is done by removing weak boundary layers, changing surface topography, changing the chemical nature of the surfaces, and modifying the physical structure of the surface.
Abhesionrequires just the opposite. For maximum abhesion, or resistance toadhesion, the surface should exhibit the following characteristics. 1. A barrier to mechanical interlocking 2. Prevention of interdiffusion 3. Poor adsorption and surface reaction 4. Low surface tension and thermodynamic work of separation 5. Limited or no electrostatic attraction 6. Incorporation of a weak boundary layer.
Since many of the factors causing adhesion are of a chemical nature, agood abhesive must also be chemically inert toward the two materialswhose adhesion are to be prevented.Abhesion, therefore, occurs via one of two primary modes:(1) prevention of adhesion to the abhesive coating layer, or(2) an easily separable coating or cohesively weak boundary layer.Thus, there are several ways in which abhesives can be classified. Themost popular classifications are permanent (corresponding to 1 above)and sacrificial (corresponding to 2 above).Several examples of each are readily evident in the householdenvironment. The coating on a non-stick baking pan is an example ofpermanent abherend.Flour, grease, or oil used for non-stick baking are examples of sacrificialabherends.of release.
Permanent abherends require that the abhesive material have goodspreading tendency on the material to be protected and a surface thatexhibits poor spreading tendency to the material which adhesion is to beprevented.The permanent abherend must be a good coating material (i.e., easilyapplied, uniformly spread over the surface to be protected, and relativelypermanent during all expected processes).Sacrificial abherends require only that the abhesive material fill the poresor smooth-out the roughness of a surface (e.g., an inert powder on arough metal surface).Sacrificial abherends generally remain attached to both surfaces afterrelease, and they must be applied to a surface every time it is to beprotected. On the other hand, permanent abherends will last throughmany cycles of release.
An important factor in choosing an abhesive is temperaturedependence.A material could act as an abhesive at room temperature and as anadhesive at elevated temperatures.Thermoplastic polyethylene coatings are good examples of this.Polyethylene is relatively inert with a low surface energy, non-sticksurface in its solid state, but it has good adhesive properties in themolten state.Another factor to be considered in choosing an abhesive is volatility.Water would be a good abhesive, but because it vaporizes at relativelylow temperatures, water could not be used as a mold release in manyhigh temperature applications.
TheoryTwo solid materials generally do not adhere to each other becausewetting does not take place and there is no penetration or interdiffusionof one material into the other.When wetting is minimal, the secondary van der Walls bond forces thatprovide the majority of molecular adhesion are not large, the work ofadhesion is minimal, and the surface has the properties of a goodabherend.Wetting can be determined by contact angle measurements
Figure 1: Interaction of the same liquid with surfaces of different surface tension (mJ/m2 = dyne/cm).A simple view of the relationship of wetting and adhesion is provided byFigure 1. Here the contact angle of a drop of a liquid on a surface ofdifferent critical surface tension is shown. The expected bond strengthswould increase as the contact angle decreases. Therefore, best abhesivescenario is when the contact angle is greatest.
After intimate contact is achieved between adhesive and adherendthrough wetting, it is believed that permanent adhesion resultsprimarily through forces of molecular attraction. Four general typesof chemical bonds are recognized as being involved in adhesionand cohesion: electrostatic, covalent, and metallic, which arereferred to as primary bonds, and van der Walls forces that arereferred to as secondary bonds.
Types of Abherend materialsThere are many materials that can be used as abhesives. These aregenerally classified chemically as shown in Table 1. They can besupplied in many different forms such as fluids, waxes, greases,emulsions, dry films, and solid powders. Many commercial abhesivesare of proprietary composition. These products can be formulations ofmore than one type of abhesive with modifiers or additives, such asemulsifiers, biocides, solvents, etc., incorporated into the final product.
Silicates TalcInorganic Clay Kaolin, micamaterials Other Silica, graphite Polydimethylsiloxane, Silicones polyalkylmethylsiloxane Fluorocarbons PolytetrafluoroethyleneSynthetic Other Poly(fluoroacrylates),polymers fluoropolymers poly(fluoroethers) Polyolefins Polyethylene, polypropylene Other Polyvinyl alcoholFluorinated Fluorinated fatty Perfluorolauric acidcompounds acids and alcohols
All abhesive materials are characterized by providing a low energysurface, and any liquid placed on such a surface will exhibit acontact angle, which will be larger as - increases. When is largeenough, such poor adhesion will occur that the application of amodest external stress will cause the bond to separate. Table 2gives values of for common abhesive materials.
Now BASF – India and Prathith Consultants , offera water based Release coating agent ( NonSilicone ) for backsizing applications, in themanufacture of Self wound Self adhesive Tapes.There a number of applications for our product.The Prdost Data sheet as wellas the variety ofapplications for the same , are shown in the slidesto follow.
This is an aqueous, finely divided emulsion of a very hard poly- ethylene wax with a highmelting point. It is manufactured under pressure by means of a special BASF process.This conforms to the requirements of various FDA regulations on account of its chemicalcomposition and the process by which it is manufactured.Microbial attack This is fully protected against microbial attack during transport, butbiocides need to be added in order to prevent problems with microorganisms fromoccurring during storage and processing. Careful attention has to be paid to the hygieneof storage facilities.Low-temperature stability It is not advisable to store This in the open during winter.Measures should be taken to prevent it from freezing. If it does freeze, the best course ofaction is to thaw it gradually by leaving it to stand at room temperature. It should not beheated directly. It is advisable to filter reconstituted dispersions before use.Shelf life This has a shelf life of one year in its sealed original packaging, provided it isstored properly. Drums should be tightly resealed each time material is taken from them.We would recommend filtering this product before use if it has been left in storage forlong periods or if a crust has formed on the surface due to the evaporation of water.
ApplicationsThis is particularly versatile on account of the balancedcombination of hardness, toughness and elasticity of thepolyethylene wax on which it is based.Overprint varnishes The wax contained in this is veryhard, which makes it very effective in overprint varnishesapplied to paper and plastic film in the packaging industry,etc. It usually needs to be applied at a rate of 8 – 10 %,expressed as a proportion of the overall formulation.
Paper and board this coating , because of the hardness of the wax on which it isbased, can be used in combination with film-forming agents toincrease the resistance of paper to scratching and mechanicalaction.conforms to the requirements of various FDA regulationsconcerning coatings applied to paper and board for food-contactapplications.Polyurethane coatingsThis coating is very effective for improving the scratch resistance ofwater-based polyurethane coatings, such as those applied toparquet floors.Printing inksThis coating can be added to water-based printing inks to improvetheir abrasion resistance. It also reduces the sliding friction ofprinted surfaces.
Textile finishingThe high hardness and the low friction of the wax containedin, combined with the very high stability of dilute emulsions, makes it veryeffec- tive in finishes applied to textile fabrics in order to improve theirsewability, abrasion resistance and tear resistance, etc.Floor polishes Dry-bright polishes can be formulated with in combinationwith styrene-acrylic polymer dispersions. The wax contained in is very hard andtough, and this enables dry-bright films with exceptionally hard-wearing filmswith high traffic resistance to be obtained.is compatible with all conventional polymer dispersions, resin solutions,plasticizers, film-forming agents and surfactants.
FDA Paragraph 21 CFR175.105 Adhesives176.170 Components of paper and paperboard in contact withaqueous and fatty foods176.180 Components of paper and paperboard in contact withdry food177.1390 High-temperature laminateswww.basf.com/detergents-formulators
SafetyWe know of no ill effects that could have resulted from using thiscoating for the purpose for which it is intended and from processing itin accordance with current practice. According to the experience thatwe have gained over many years and other information at our disposal,this does not exert any harmful effects on health, provided that it isused properly, due attention is given to the precautions necessary forhandling chemicals, and the information and advice given in our safetydata sheet are observed.
NoteThe data contained in this publication are based on our current knowledge andexperience. In view of the many factors that may affect processingand application of our product, these data do not relieve processors fromcarrying out their own investigations and tests; neither do these data implyany guarantee of certain properties, nor the suitability of the product fora specific purpose. Any descriptions, drawings, photographs, data, pro-portions, weights etc. given herein may change without prior information anddo not constitute the agreed contractual quality of the product. It is theresponsibility of the recipient of our products to ensure that any proprietaryrights and existing laws and legislation are observed.
Here are some specialty Tapes , selfwound , that need , a easy release , onunwinding.There are lot may options available as oftoday.We have now something to offer Ex.Stock, water borne.
ForFabrics basedTapes Fibre Glass Cloth TapesUni and Bi directionalPolyester Tapes
For Foil / Alu Glass TapesAluminium FoilTapes Alu Glass Tapes
ForPet / PE , filmbased Tapes PET Holding Tape PE Surface Protection Tape PET PET Application Electrical Tape Insulation Tape
Adhesive Coater for self wound Tapes with our backsizing solutionAdhesiveCoatingstation
The requirements of ,Backside non- Silicone release coating ( which is alsotermed as Abhesive ) are,4.It has to be quick drying.5.It must be non curing type , no chemical reaction or Crosslinking is involved.6.Very very low coat weight.7.Should not interfere with the PS Adhesive , or lower thepeel adhesion , due to unwanted pick up of the releasecoating by adhesive8.Must be cost effective9.Ability to coat in single pass , along with adhesive.
The Advantages of ourNon Silicone Release Coat (Poligen WE 6 ) Ex Stock availability Purely water based Quick drying Very cost effective as compared to Imported products Especially highly suitable for the manufacture of Surface protection Tapes on , co-extruded Poly Ethlene Films
For more details on the TDS , Freesample for machine trials , assistancefor machine trials, minor machinemodifications etc., contact us on Email : firstname.lastname@example.org Or Mobile : 07588288204 Email : Shyam.email@example.com Or Visit us on : www.psadhesive.com