TECH 31 Papers
Spray Coating -- A Contactless Coating Process for Paper Finishing
Niels Czerwonatis, Ph.D.
tesa AG
The coating of surfaces is done by atomization in a lot of technical processes (e.g., painting). Spray coating features different advantages: the coating is carried out contactless, and a contour coat can be applied on even surfaces. The challenges of coating a web over its entire surface with a spray are discussed. Different relevant atomizers are introduced. Their mode of operation and their properties are explained. Different paper grades were spray-coated by different processes. The resulting characteristics and qualities were measured and compared to standard coated paper.
Heat Activated Pressure Sensitive Adhesives
Yadunandan L. Dar, Ph.D.
National Adhesives
This paper describes a heat activated pressure sensitive adhesive (PSA) coating, which shows no PSA properties until heated to a suitable temperature. The heat converts the non-adhesive coating to a pressure sensitive adhesive, which retains aggressive tack and demonstrates properties similar to a conventional PSA coating even after the heat source is removed. This technology works through encapsulating a PSA core material with a high-Tg polymeric shell in aqueous dispersion. The high-Tg stabilizer forms a protective encapsulating matrix around the core particles, which are preserved intact within the coating formed from the dispersion. This morphology provides a non-tacky film surface and is disrupted upon activation resulting in a tacky film surface.
Rheological Properties and Adherence Performance of Pressure Sensitive Adhesives: the Case of Adhesion on a Viscoelastic Substrate
Christophe Derail
Université de Pau et des Pays de l'Adour
The presentation deals with the viscoelastic and adherence properties of pressure sensitive adhesive formulations dedicated to medical applications and the different results that we have obtained on the adherence properties of PSA.
We have developed a specific configuration test to measure the adherence properties of PSA on a viscoelastic substrate which mimics the mechanical properties of human skin. We show that the material used offers a better representation of the interactions present at the skin/adhesive interface, in comparison with classical surfaces used for the peel test (glass, steel) which have higher surface tension. Surface topography of a real skin was achieved by molding the film on an aluminum plate where the surface was subjected to chemical abrasion affording similar roughness as human skin. To validate our model, we present peel results performed with different industrial formulations on our substrate and for in vivo tests.
After the validation of our substitute, we describe several experiments, dedicated to obtaining a better knowledge of the adhesion on a complex substrate, i.e., identify the contribution of each element of the system studied in the peel test and apply rules, well-known in industrial applications.
The Nature of Natural Rubber Viscoelastic Variation
John Dick
Alpha Technologies
Natural rubber is extensively used as an important raw material by the pressure sensitive adhesives industry. However, the normal quality variation is relatively high compared to synthetic polymer alternatives. This paper discusses measurements of the magnitude and nature of this natural rubber quality variation using a special dynamic mechanical rheological tester. Also, the paper discusses some of the causes of this variation and the new ASTM standard (D7050) that describes how effective sorting can be implemented to improve product consistency.
Advanced Polyolefin Foam Carriers for an Evolving Market
Anthony Filip
Sekisui Voltek LLC
Advancements in pressure sensitive adhesive (PSA) technology and the evolving market demand thin, high-quality, precision foam tape substrates. Applications range from simple static part-to-part assembly to dynamic applications where the compression performance is critical. Through the application of new technologies which provide improved process capability, Sekisui Voltek LLC has developed a new family of precision foam products designed for the tape industry. For the innovative tape designer, this paper explores these recent advances in crosslinked polyolefin foam technology and the advantages they bring to the market.
Good Vibrations
Paul B. Foreman
National Adhesives
The ability of pressure sensitive adhesives to absorb and dissipate energy has led to their widespread use in vibration damping applications. This paper discusses measurement of damping, the requirements for outgassing in computer disk drives and the methods by which PSA damping properties can be modified for a particular application.
Microporous Polypropylene Films for Tape and Label Applications
Philip Jacoby, Ph.D.
Mayzo, Inc.
We have developed a unique masterbatch that can be used to produce extruded polypropylene sheet containing high levels of beta phase crystallinity. When this sheet is stretched either uniaxially or biaxially to produce MOPP or BOPP film, the sheet undergoes extensive microvoiding resulting in a white/opaque appearance and a significantly reduced density. The film also has improved printability. Under certain circumstances it is possible to produce a microvoided film that has very high moisture vapor transmission rates, so that the film is "breathable" while also being waterproof.
These microvoided films are less expensive to produce than conventional white films since the density reduction yields more square yards of film per pound of resin used, and the level of Ti02 pigment that is required is drastically reduced. Application areas for these films include tape, labels, synthetic paper and protective clothing.
Making the Pie Bigger: Developing New Products and Applications
Timothy B. Jensen, Ph.D.
Retired 3M
It is easy to take the size and success of the tape industry for granted; our products are widely used in everyday activities and settings ranging from hospitals to automobile repair shops, from offices to loading docks. In order to secure our future growth, we need to "make the pie bigger."The strategy of fighting for market share is well understood; the strategy of developing new products and applications is not so well understood. In this paper, we cover some of the new products of the past and attempt to uncover some rules of innovation for making the market bigger.
REACH: How it Affects PSA Tapes
Brian Johnson
3M
This presentation reviews the Registration, Evaluation, Authorization of Chemicals (REACH) regulation with a focus on RIP 3.8 which provides guidance on articles like tape products. This presentation also includes discussion of the article notification and communication requirements under REACH and the substances of very high concern candidate list.
Low Temperature Silicone Release Coatings for Temperature Sensitive Films
John Kilgour, Ph.D.
Momentive Performance Materials
Temperature sensitive films such as polypropylene, polyethylene and poly-coated papers are among the fastest growing segments of the release liner industry. Until now, silicone release coatings for these substrates have been limited to expensive UV cured formulations, very high platinum thermal solventless or slower, environmentally difficult solvent based coating. Based on breakthrough discoveries in the hydrosilylation catalyst, silylhydride crosslinkers and vinyl polymers, a novel silicone coating formulation has been created for coating on temperature sensitive films at temperatures as low as 80°C at rapid line speeds. This paper elaborates on the chemical discoveries for thermal solventless formulations as well as demonstrates commercial applications with siliconized olefinic liners for mastics, acrylate and hot melt adhesives.
Continuous Production of Adhesives Compounding
Alessandro Maris
F.lli MARIS S.p.A.
Continuous adhesives compounding has been in place more than 20 years. In this period of time, the Maris company has been engaged in constant improvement of mixing process performances using the co-rotating intermeshing twin screw extruder.
The most recent release is the continuous production of solvent based adhesive by extrusion, specifically dedicated to those products which involve natural rubber and hydrocarbon or aromatic solvents. The use of the co-rotating twin screw extruders introduces benefits to several aspects of this application, such as improved quality consistency, short production time (limited to 15-20 minutes), fast response to recipe modification, limited quantity of solvent used in cycle at any moment and online monitoring of the adhesive viscosity.
Silicone PSA: Solid State Solution of MQ Resins in Polyorganosiloxanes
Mieczyslaw Mazurek, Ph.D.
3M
Silicone PSAs, adhesives, elastomers and release coatings often contain various amounts of silicate resins, most common of which is the MQ-type resin. Although the role of these resins in the listed systems differs from tackification (PSAs) through reinforcement (elastomers) to modification of the release level (release coatings), one can expect that the underlying mechanisms in all of these systems share some commonality. We have reported earlier some preliminary results of the rheological studies of "standard" silicone PSAs and their constituent components in support of the phenomenological model presented by the GE researchers, involving the molecular level interactions between polyorganosiloxane chain and MQ.
We have recently studied silicone PSA based on the silicone polyurea copolymers. The effect of the composition, of the coating solvents and of the drying conditions on the properties of PSAs are reported, which further corroborates the hypothesis of the formation of the solid-state solution of MQ in polydimethylsiloxane (PDMS) in the MQ-modified PDMS systems.
2008-2009 Economic Outlook
John McDevitt
Economic Consultant
John McDevitt's economic trend analysis has become a tradition at PSTC meetings. His global overview, coupled with an in-depth analysis of current market trends, offers a thorough view of economics and its influence on the pressure sensitive adhesive tape industry.
Quick & Dirty GRR Procedure to Rank Test Method Variability
Michael Mercer
3M
Measurement systems analysis (MSA) is a topic of interest to those in the tape industry who supply the automotive and other OEM industries. MSA requires gage repeatability and reproducibility (GRR). This paper proposes a quick and dirty GRR study using a MinitabTM I-MR-R/S Chart to obtain estimates of the test method repeatability standard deviation and the GRR ratio which can be used to rank test methods for subsequent study.
No additional effort is required for test methods which use repeated values to report an average. This procedure can be applied to PSTC test method numbers 6, 8, 16, 34, 35, 38, 39, 50, 107, 131, 133, which all require multiple repeated measurements. This procedure may also be applied to test methods that use only one measurement; in this case a second measurement is collected for a short period of time.
Patent Marking: A Beginner's Guide
Jeffrey Metzcar
Thompson, Hine & Flory
A patentee who makes or sells patented articles, or a person who does so for or under the patentee, is required to mark the articles with the word "Patent" and the number of the patent. The penalty for failure to mark is that the patentee may not recover damages from an infringer unless the infringer was duly notified of the infringement and continued to infringe after the notice.
This presentation focuses on patent marking, as follows:
- Why do you want to mark an article?
- How do you mark an article?
- Why would you not want to mark?
- What are the patent marking strategies?
Recent Developments in Halogen Free Flame Retardant Pressure Sensitive Hot Melt Adhesives (HMPSA)
Krishna Nookala
Collano AG
Adhesive tapes and self adhesive coated materials are used in various industries and in multiple applications. A multitude of applications further requires that the adhesive does, at least, not impair the flammability behavior of the complete system. In some cases the adhesive should even reduce the flammability. Due to their nature, pressure sensitive hot melt adhesives are not particularly suitable for this purpose. The demand for halogen free flame retardant adhesives, which do not emit toxic fumes during a fire, poses an additional barrier. The paper gives an update about recent developments and an outlook for opportunities with flame retardant pressure sensitive hot melt adhesives.
Advances in Acrylic Emulsion PSAs for Use with
Polyolefin Foam Carriers
Thomas Reffle
Rohm and Haas Company
Foam tape designers have historically relied on solvent borne PSAs for high performance applications such as mounting, vibration damping and construction. Recent advances in polymerization technology have led to acrylic emulsion PSAs which match solvent acrylic and synthetic rubber adhesives for anchorage to high density polyolefin foams. This water borne technology also delivers the exceptionally high cohesive strength and resistance properties (heat, humidity, plasticizer) required for many foam tape applications. The economic, environmental and worker safety advantages of eliminating solvent based products are well known, and particularly timely given current global considerations. This paper presents a brief overview of acrylic, PU, PVC and PO foam tape designs, properties and end uses, with a focus on the role of these new acrylic emulsion PSAs in combination with novel high density PO foams.
Complete Release Core (CRC) for Medical Tapes
Tony F. Rummage
Sonoco Products Company
Medical tapes typically exhibit low to medium adhesive aggressiveness. Typical fiber cores, onto which medical tapes are wound, have paper surfaces. The aggressiveness of medical tape frequently causes the inside wrap of tape to tear and split the paper tube surface, rendering the inside wrap of tape unusable. Tape manufacturers wind extra tape equivalent to the inside wrap to offset the lost product. Medical tape roll lengths have historically been 10 yards or greater. Due to recent liability issues, the medical industry is trending to single use medical kits, in which tape length may be as short as 18 inches.
Shorter tape lengths became a driver to develop a core allowing complete unwind -- 100 percent use of the medical tape. Using a unique film surface and a proprietary, patented manufacturing process Sonoco developed a complete release core during 2006. The new CRC is being commercialized on 3M microfoam medical tape.
Styrenic Block Copolymers in Adhesives for Co-extruded Films
David St. Clair, Ph.D.
Kraton Polymers
Styrenic block copolymers are widely used in pressure sensitive adhesives which can be applied by hot melt coating. SBCs can also be used in compounds which have higher melt viscosity that are suitable for use in a coextrusion process. This paper shows that compounds can be formulated which, when co-extruded with polyolefins, give films with adhesion values that can be controlled over a wide range, from very low to semi-pressure sensitive. The compounds are based on the hydrogenated SBCs, so they have good UV and thermal stability. Films can be co-extruded on either cast or blown film equipment, thus reducing costs by eliminating a separate adhesive coating step. These films are particularly well suited for use as surface protective films.
Recycling Compatible Hot-Melt and Water-Based Pressure Sensitive Adhesives
Steven J. Severtson, Ph.D.
University of Minnesota
Pressure sensitive adhesive (PSA) contaminates post consumer waste impeding its processing and limiting the use of recovered cellulose fiber. An approach for reducing the impact of PSA on recycling operations is to redesign label systems to inhibit fragmentation of adhesive films. This results in residual PSA particles that are more easily removed from the process with conventional mill contaminant control equipment. In this presentation, findings are reviewed from research aimed at the development adhesive films that have little or no negative impact on recycling operations. Both hot-melt and water-based formulations were examined, which combined, account for much of the PSA paper label market. For both types of PSAs, properties of the base polymer or polymer blend govern, to a great extent, fragmentation behavior during processing, but via very different mechanisms. The role of laminate design and processing aids in determining the fragmentation behavior of adhesive films are discussed.
Photocrosslinking of Acrylic Hot Melt PSAs Using Multifunctional Benzopheonones
Audrey A. Sherman
3M
It is known that crosslinking polymers produces networks, which have quite different mechanical and physical properties compared to their uncrosslinked linear or branched counterparts. To cure acrylic PSAs, a variety of different materials have been used as crosslinking agents, e.g. polyfunctional acrylates, acetophenones, benzophenones and triazines. These crosslinking agents, however, possess certain drawbacks which can include high volatility; incompatibility with certain polymer systems; generation of corrosive by-products; generation of undesirable color; a separate photoactive compound to initiate crosslinking reactions; or high sensitivity to oxygen.
Bis-benzophenone type crosslinkers are an effective and convenient method to crosslink hot-melt PSAs. They work in a variety of polymer systems and can be readily adjusted to allow for easy fine-tuning of gel content and cohesive strength of the cured product. They can be synthesized using readily available raw materials and standard organic chemistry, making them economically viable photocrosslinkers that yield covalently crosslinked materials upon exposure to UV irradiation.
Taking Pressure Sensitive Adhesives to a Different Level of Performance
Robert Wigdorski
Adhesives Research Inc.
Liquid adhesives are routinely used for product assembly and process applications due to the strength these adhesives provide in the finished assemblies; however on many occasions there is a desire to use pressure sensitive adhesives (PSAs) for these end uses due to ease of use. This desire is often lost because the strength of the PSA systems does not match the end use requirements. Pressure sensitive adhesives with various cure mechanisms covering materials that convert from normal pressure sensitive performance to systems providing dynamic shear strength exceeding 690 N/sq cm as well as systems that convert to ultra removable peel strength (0.3 N/25.4 mm) are presented. Performance properties such as resistance to temperature extremes ranging from -25°C to 100°C, exposure to water immersion and high temperature/high humidity are covered as well.
Design of Responsive Structured Adhesive Surfaces Based on the Gecko Adhesive System
Boxin Zhao
University of California at Santa Barbara
The gecko foot is a natural pressure sensitive adhesive, which can stick strongly to almost any surface, whether rough or smooth, hydrophilic or hydrophobic, dry or wet, then detach with equal ease and rapidity. This adhesive ability has been attributed to the millions of finger-like pads (spatulae) that have nano-scale dimensions, which allow for a large "real" contact area and a high density of van der Waals "bonds" to form. We analyze the structural, mechanical and physico-chemical properties of the spatulae, the setal stalks to which they are attached, the setal arrays on the gecko toes and in particular the way the toes move during attachment and detachment to establish the mechanics and conditions that allow for the gecko's remarkable abilities. We describe results of the adhesion forces of setal arrays using the surface forces apparatus, and conclude that the design of synthetic analogs require asymmetric surface structure and motions during attachment and detachment.
