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Pressure sensitive adhesive (PSA, self adhesive, self stick adhesive) is adhesive that forms a bond when pressure is applied to marry the adhesive with the adherend. No solvent, water, or heat is needed to activate the adhesive. It is used in pressure sensitive tapes, labels, note pads, automobile trim, and a wide variety of other products.
As the name "pressure sensitive" indicates, the degree of bond is influenced by the amount of pressure which is used to apply the adhesive to the surface.
Surface factors such as smoothness, surface energy, removal of contaminants, etc. are also important to proper bonding.
PSAs are usually designed to form a bond and hold properly at room temperatures. PSAs typically reduce or lose their tack at cold temperatures and reduce their shear holding ability at high temperatures: Specialty adhesives are made to function at high or low temperatures. It is important to choose an adhesive formulation which is designed for its intended use conditions.
Electrical grade PSAs are critical components in the design many of today's electrical and electronic components in the electrical industry. The construction of this type of PSA is difficult since lower concentration of conductive filler must be used in order to prevent the drying out of polymer by the conductive filler, with attendant loss of tack. The conductivity of electrically conductive PSA in the direction of pressure action is to a certain extend depend on the direction of pressure applied Florian, 2003
Electrical grade PSAs are designed and manufactured using materials using material that are physically and chemically stable in the presence of humidity and electrical stress. The acrylic high tack PSAs works very well in static and dynamic joints. The PSA agents are used in three forms i.e. modified aqueous dispersions or solutions in different solvents and as hot melts adhesives. PSA tapes find application in electronic assemblies Reliability of Pressure-Sensitive Adhesive Tapes for Heat Sink Attachment in Air-Cooled Electronic Assemblies
While mechanical fasteners will always be the choice when maximum torque and linear force are required in automobile industry, pressure-sensitive adhesives (PSAs) can often provide a better method of joining or bonding than traditional screws, nuts, bolts, rivets and welds.
The design, performance, and production reasons for replacing mechanical or fusion fastening methods with PSAs include, but are not limited to:
Increasing production efficiency: PSAs reduce material requirements, provide product weight reduction, require fewer assembly and finishing steps, and minimize training FLEXcon white paper
There are two essential requirements of medical PSAs, that they should stick firmly to a difficult substrate (skin) and that they should be easily and cleanly removed from that substrate when desired. These requirements would seem to be in conflict: a high peel force usually signals the ability to stick firmly, while a low force is needed when removing dressings by peeling.
A number of ways have been considered to resolve this conflict. These may be divided into two broad categories: those that make the best of existing PSA technology, broadly taking a physical approach, and those that introduce novel chemistry into the process. Physical approaches consider such details as the dependence of peel force on peel angle, peel rate, backing materials, the deformation of the skin during peeling and use of barrier films and solvents. As an alternative to simply making the best of the physics of the peeling process, various workers have devised chemical systems for making the adhesive less strongly adhering at the time of removal. These systems usually consist of introducing a ?switch? mechanism into a strongly adhering adhesive so that its adherence may be reduced significantly at the time of removal by operation of the ?switch?. Means of activating the ?switch? include: heat (warming or cooling), application of water via an absorbent backing and exposure to visible light. These may produce physical or chemical changes in the adhesive Chivers, 2001
Transdermal or through-the-skin delivery of drugs has assumed an important place in drug therapy, eliminating many of the shortcomings of syringes and pills. Active Transdermal Delivery Systems The three most commonly used adhesives used for transdermal delivery are polyisobutylenes, polyacrylates and silicones Tan and Pfister, 1999
Aerospace manufacturers uses PSAs to assemble sheet-metal components into sub assemblies. The aerospace industry, primarily satellite manufacturers, have expressed the need for a low outgas, thermally stable, adhesive tape which can work at both high, 175ēC, and low, -100ēC, temperatures. New silicone PSA was fabricated to pass, low outgassing requirements of 1% or less Total Mass Loss (TML) and 0.1% or less Collectable Volatile Condensable Materials (CVCM) Riegler, 2005.
Although PSPs can be obtained by different polymerization processes (i.e., emulsion, solution, hot-melt, or radiation curing), much attention has recently been devoted to the utilization of more environmentally friendly processes such as emulsion polymerization. Soft polymer networks are commonly used as previous termpressure sensitive adhesivesnext term (PSAs). This is due to their unique ability to deform and yet to resist flow. These contradictory requirements indicate that the mechanical properties are finely tuned, and that the types of deformation upon application are carefully considered. Variety of PSAs can be prepared by mixing a linear vinyl terminated polymer with a silane terminated f-functional cross-linker. Jensen et al., 2009
Sr. No. | PSA process | Chemical composition | Time of launch |
1 | Solvent-based | Rubber/resin, acrylics, silicones | Since 19th century |
2 | Hot-melt | Block copolymers, acrylics | 1940s |
3 | Emulsion (water)-based | Acrylics, natural and synthetic rubber, ethylene-vinyl acetate copolymer | 1970s |
4 | Radiation-cured | Acrylics, rubber | 1970s |
Sr. No. | Properties | Solvent-based: acrylic | Hot-melt: styrene-isobutylene-styrene. | Emulsion based: acrylics |
1 | PS performance | Excellent | Excellent | Very good |
2 | Ease of compounding | Moderate | Difficult | Easy |
3 | Formulation flexibility | Limited | Excellent | Moderate |
4 | Coating method flexibility | Limited | Poor | Excellent |
5 | Ease of changeover | Limited | Poor | Excellent |
6 | PSA reproducibility | Excellent | Limited | Excellent |
7 | Aging properties | Excellent | Poor | Excellent |
8 | Clarity/color | Excellent | Poor | Excellent |
9 | Safety/toxicity | Poor | Poor | Excellent |
10 | Raw material costs | High | Low | Medium |
11 | Coating/compounding costs | High | Medium | Low |
In a study wherein polymer molecular weight and polymer microstructure were regulated using different chain transfer agent (CTA) concentrations and by addition of a diacrylic monomer (MM) it was shown that all of the measured adhesion properties strongly depend on molecular weight of the synthesized polymer and on the amount of gel phase Kajtna et al., 2009
In a study it was shown that the mechanical behaviour depend on their composition but majority of fracture energy is dissipated on the first millimetre near the bending zone where fibrils elongation is maximum. Observations of interfaces between PSAs and glass substrate underline that fracture energy varies linearly according to the contact area Horgnies et al., 2007
To study the effect of tackifier (such as hydrogenated cyclo-aliphatic resin) a model system consisting of polystyrene-b-polyisoprene-b-polystyrene triblock copolymer was prepared. Tackifier increased the peel adhesion significantly and the increase became stronger above 40 wt% tackifier. The higher peel adhesion was obtained in the system with the larger amount of agglomerates of tackifier in the polyisoprene matrix. Sasaki et al., 2008
In a study it was shown that a constant cross-linker concentration, one can manipulate the polymer micro-structure by adding varying amounts of chain transfer agent. Three examples of these micro-structures are depicted below which show a tight gel network with long-chain sol polymers, a loose gel network with shorter sol polymers, and an imperfect gel structure with highly branched sol polymers. By manipulating the micro-structure, previous termpressure-sensitive adhesivenext term performance can be affected. Qie and Dube, 2010
The fracture energy (fracture toughness) of tapes during globally elastic unpeeling is often calculated from the relation G=P/b(1?cos ?). A study suggested that this expression is correct for elastic peeling from rigid substrates but it gives misleading results when peeling from reversible flexible substrates. Steven-Fountain et al., 2002
PSAs polymeric materials effect tack, peel and shear strength . Inherent properties such as copolymer composition and microstructure, molecular weight and distribution are among the most influential factors affecting PSA properties directly as well as indirectly through their influence on physical properties (e.g., the glass transition temperature, Tg) and thus, rheological properties of the polymer (e.g., viscoelastic regions, moduli).
Therefore, PSA is the result of a fine balance between these three major, interrelated properties.
It is a measure of the force required to remove, say a foam gasket and its adhesive, from the substrate. It usually refers to the initial attraction of the adhesive to the substrate. Tack can be measured by four basic methods these are loop tack, rolling ball, Quick stick and probe measurement devices. Review Of Methods For The Measurement Of Tack
Peel strength is measured as a force required to remove a standard PSA strip from a specified test surface under a standard test angle (e.g., 90° or 180°) under standard conditions. Much like tack, manufacturers control adhesion to create different products based on user requirements. After a PSA has been applied to the substrate, adhesion continues to increase for a period of time ? typically 24 hr.
Shear strength is the internal or cohesive strength of the adhesive mass. Usually, it is determined as the length of time it takes for a standard strip of PSA to fall from a test panel after application of a load. Usually, tack and adhesion decrease as shear strength increases. Emulsion-Based Pressure-Sensitive Adhesives: A Review
The most common products that utilize PSAs are tapes, labels, and protective films. The PSA sector is among the fastest growing in the adhesive market, making the search for new pressure-sensitive products (PSP) and applications highly competitive.
PSAs exact a considerable cost on the paper recycling industry, an estimated $700 million per year. Most paper recycling systems converts paper into pulp in presence of water, which is then transformed back into paper. PSAs do not dissolve in water, but rather fragment into smaller particles during the repulping process. These particles are known as stickies, get deformed under heat and pressure, making them difficult to screen or filter out of the pulp. Stickies can become lodged on papermaking and can cause damage to equipment or even in the paper. Source
Sr. No. | "Sticky" PSA Product | Alternative Product/Procedure |
1 | Address Labels | 1. Print addresses directly on envelopes 2. Using glassine (cellulose) film window or filmless window envelopes, and print mailing addresses directly on the letter to show through the window. 3. Handprint addresses directly on large mailing envelopes.. |
2 | Sticky Notes | 1.Use scratch paper for notes and secure with paper clips. |
3 | Postage Stamps | 1. Use moisture-activated postage stamps 2. Postal meter that prints postage directly on envelopes or that uses moisture-activated meter tape |
4 | File Folder Index Labels | 1. Handprint file subjects directly on index tabs, instead of using an index label. When recycling file folders with index labels, tear off the index tab. |
5 | Closure Tabs | 1. Sharply folding fliers and newsletters is often sufficient to send them safely and securely through the mail. |
Search strategy last updated on: 7th January 2011
Sr. No. | Search string | Hits |
1 | Pressure sensitive adhesive making | 7,510,000 |
2 | Pressure sensitive adhesive application | 7,650,000 |
3 | Pressure sensitive adhesive automobile | 436,000 |
4 | Pressure sensitive adhesive automotive | 479,000 |
5 | Pressure sensitive adhesive drug delivery | 275,000 |
6 | Pressure sensitive adhesive tack* | 354,000 |
7 | Pressure sensitive adhesive product | 8,120,000 |
8 | Pressure sensitive adhesive recycl* | 447,000 |
Google scholar | ||
1 | Pressure sensitive adhesive making | 21,50,000 |
2 | Pressure sensitive adhesive application | 21,50,000 |
Scirus | ||
1 | Pressure sensitive adhesive making | 130,055 |
2 | Pressure sensitive adhesive application | 200,950 |
3 | Pressure sensitive adhesive product | 136,169 |
Sciencedirect | ||
1 | Pressure sensitive adhesive electronics | 2,450 |
2 | Pressure sensitive adhesive making | 7,212 |
3 | Pressure sensitive adhesive application | 15,405 |
4 | Pressure sensitive adhesive automobile | 951 |
5 | Pressure sensitive adhesive automotive | 1,406 |
6 | Pressure sensitive adhesive drug delivery | 2,876 |
Springerlink | ||
1 | Pressure sensitive adhesive making | 2,149 |
2 | Pressure sensitive adhesive application | 3,901 |
Google images | ||
1 | Pressure sensitive adhesive making | 3,580,000 |
2 | Pressure sensitive adhesive application | 2,210,000 |
3 | Pressure sensitive adhesive electronics | 1,690,000 |
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Query.No. | Searched Sections | Years Searched | Query | Hits |
1 | Claims, Title or Abstract | 1836 ? Date | (rubber OR acryl* OR silicone OR oil*1 OR resin*1 OR ethylen* OR isoprene OR terpene OR copolymer* OR vinyl* OR siloxane* ((acid OR anhydride) ADJ1 (acrylic OR crotonic OR (vinyl ADJ1 acetic) OR fumaric OR maleic OR malonic OR succinic OR itaconic OR citraconic)) OR polymer* OR styrene OR ester*) SAME (((pressure ADJ1 sensitive) NEAR2 (adhesive* OR glue OR paste OR (binding ADJ1 agent) OR (epoxy ADJ1 resin*) OR film) OR PSA OR PSAs) OR (adhesion* WITH (peel OR tensile OR shear) OR stick*) OR (radical* ADJ1 (initiator* OR maker*))) | 76006 |
2 | Claims, Title or Abstract | 1836 ? Date | (((low ADJ surface ADJ energy) WITH (substrate*1 OR polymer OR compound* OR material OR film)) OR (surface ADJ1 tension) OR (surface ADJ1 rough*) OR viscosity OR (oily ADJ surface) OR (low ADJ1 energy ADJ1 surface*)) AND (polyolefin*1 OR polyethylene*1 OR polypropylene*1 OR (polyvinyl ADJ1 chloride ADJ1 film) OR (oil ADJ1 contaminated ADJ1 metal) OR polybutene OR polyisoprene*1 OR (polyvinylidene ADJ1 fluoride*) OR polytetrafluoroethylene*1 OR polyester*1 OR polyamide*1 OR polyacetal*1 OR polystyrene*1 OR polyurethane* OR polyurea OR silan* OR polycarbonate*) | 75602 |
3 | Claims, Title or Abstract | 1836 ? Date | 1 AND 2 | 2272 |
This is only a sample report with brief analysis
Dolcera can provide a comprehensive report customized to your needs
Assignees | Rubber | Silicone | Polymers | Acrylic | Tackifying resin | Plasticizer oil | Carboxylic acids | Acid Esters | Priority Year | Patent numbers |
3M Innovative Properties Company | x | x | x | x | x | 2000 | US6630531 | |||
x | x | x | x | 2000 | US6632872 | |||||
x | x | 2000 | US6455634 | |||||||
x | x | x | 1993 | US5612136 | ||||||
x | x | x | 1993 | US5602221 | ||||||
American Tape Company | x | x | 1997 | US5798175 | ||||||
Ashland Oil, Inc. | x | x | x | 1991 | US5434213 | |||||
Atlantic Richfield Company | x | x | x | x | 1984 | US4656213 | ||||
x | x | x | x | 1996 | US5817426 | |||||
x | x | x | 1996 | US5817426 | ||||||
x | x | 1997 | US6461707 | |||||||
Coloplast | x | x | x | 1980 | US6437038 | |||||
Dow Corning Corporation | x | x | x | 1970 | US5916981 | |||||
x | x | 1990 | US6337086 | |||||||
x | 1990 | US6121368 | ||||||||
x | x | 1994 | US5561203 | |||||||
x | x | 1996 | US5861472 | |||||||
Exxon Chemical Patents Inc. | x | x | 1993 | US5714254 | ||||||
Fujikura Ltd. | 2000 | US6388556 | ||||||||
General Electric Company | x | x | 2000 | US6387487 | ||||||
H Fuller Licensing & Financing, Inc. | x | x | x | x | x | 1996 | US5741840 | |||
H. B. Fuller Licensing & Financing, Inc. | x | x | x | 1997 | US5869562 | |||||
Johnson & Johnson Products Inc. | x | x | x | x | 1981 | US4335026 | ||||
Nichiban Company Limited | x | 1997 | US6274235 | |||||||
None | x | x | x | x | 1996 | US20030136510 | ||||
PPG Industries, Inc. | x | x | x | x | 1996 | US5776548 | ||||
Ralf Korpman Associates, Inc. | x | 1992 | US5760135 |
As it is evident from the the technology tree below, although the IP activity in the area of Pressure sensitive adhesive was initiated during 1970s, companies are continuously trying new combinations of different components.
This is only a sample report with brief analysis
Dolcera can provide a comprehensive report customized to your needs
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