Effect of zinc oxide on the viscosity and adhesion property of epoxidized natural rubber/acrylonitrile‐butadiene rubber‐based pressure‐sensitive adhesives

Viscosity, loop tack, peel strength, and shear strength of epoxidized natural rubber (ENR 50)/acrylonitrile‐butadiene rubber (NBR)–based pressure‐sensitive adhesive were studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin with loading of 40 phr was chosen as the tackifier resin. Toluene and polyethylene terephthalate were used as the solvent and coating substrate, respectively, throughout the experiment. The adhesive was coated on the substrate by using a SHEEN hand coater. Viscosity of the adhesive was determined by a Brookfield Viscometer, whereas the loop tack, peel strength, and shear strength were measured by a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that viscosity increases with zinc oxide concentration owing to the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration. This observation is associated with the effect of varying degrees of wettability of the adhesive on the substrate. Shear strength, however, increases steadily with increasing zinc oxide loading owing to the steady increase in cohesive strength. In all cases, the adhesion properties of adhesives increase with increasing coating thicknesses. J. VINYL ADDIT. TECHNOL., 22:410–414, 2016. © 2015 Society of Plastics Engineers     

Adhesion behavior of natural rubber‐based adhesives crosslinked by benzoyl peroxide

The loop tack, peel, and shear strength of crosslinked natural rubber adhesive were studied using coumarone‐indene and toluene as the tackifying resin and solvent, respectively. The concentration of benzoyl peroxide‐the crosslinking agent—was varied from 1 to 4 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on the polyethylene terephthalate substrate at various coating thickness. Loop tack, peel, and shear strength were measured by a Llyod adhesion tester operating at 30 cm min^?1. Result shows that loop tack and peel strength of the adhesive increases up to 2 phr of benzoyl peroxide concentration after which it decreases with further benzoyl peroxide content. This observation is attributed to the optimum crosslinking of natural rubber where optimum cohesive and adhesive strength occurs at 2 phr peroxide loading. However, for the shear strength, it increases with increasing benzoyl peroxide concentration where higher rate of increase is observed after 2 phr of peroxide content, an observation which is associated to the steady increase in cohesive strength of crosslinked rubber. In all cases, the adhesion properties of adhesives increase with increase in coating thickness. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Empirical Modeling of Butyl Acrylate/Vinyl Acetate/Acrylic Acid Emulsion‐Based Pressure‐Sensitive Adhesives

Summary: Butyl acrylate/vinyl acetate/acrylic acid (BA/VAc/AA) emulsion latexes were produced in a semi‐batch mode. The objective was to generate polymers with properties favoring their application as pressure‐sensitive adhesives. The influence of the individual monomer concentrations on final properties such as glass transition temperature (T_g), peel strength, shear strength and tack was investigated. To obtain the maximum amount of information in a reasonable number of runs, a constrained three‐component mixture design was used to define the experimental conditions. Latexes were coated onto a polyethylene terephthalate carrier and dried. Different empirical models (e.g. linear, quadratic and cubic mixture models) governing the individual properties (i.e. T_g, peel adhesion, shear resistance and tack) were developed and evaluated. In the given experimental region, no single model was found to fit all of the responses (i.e. the final properties). However, in all models the most significant factor affecting the final properties was the AA concentration, followed by the VAc concentration.

Shear strength contour lines over the investigated region.     

Dependence of adhesion property of acrylonitrile‐butadiene rubber‐based adhesive on zinc oxide concentration

Viscosity and adhesion properties of acrylonitrile‐butadiene rubber (NBR)‐based pressure‐sensitive adhesive were investigated by using zinc oxide as the filler. The zinc oxide loading was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin, toluene, and polyethylene terephthalate were used as the tackifying resin, solvent, and coating substrate, respectively. Viscosity of the adhesive was measured by a Brookfield viscometer, whereas the loop tack, peel strength, and shear strength were determined by a Lloyd adhesion tester operating at 10 to 60 cm/min. Results show that viscosity increases with zinc oxide loading because of the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration, whereas the optimum zinc oxide loading for shear strength is 30 phr. This observation is attributed to the effect of varying degrees of wettability and compatibility of the adhesive on the substrate. In all cases, the adhesion properties of adhesives increase with coating thickness and testing rates. J. VINYL ADDIT. TECHNOL., 23:241–246, 2017. © 2015 Society of Plastics Engineers     

Effect of silica on viscosity,tack, and shear strength of epoxidized natural rubber‐based pressure‐sensitive adhesives in the presence of coumarone‐indene resin

The viscosity, loop tack, and shear strength of silica‐filled epoxidized natural rubber (ENR 25 and ENR 50 grade) adhesive were investigated using coumarone‐indene as the tackifying resin. Silica loading was varied from 10–50 parts per hundred parts of rubber (phr), whereas the coumarone‐indene concentration was fixed at 40 phr. Toluene was used as the solvent throughout the study. Polyethylene terephthalate substrate was coated at various adhesive coating thicknesses, i.e., 30, 60, 90, and 120 μm using a SHEEN Hand Coater. Viscosity of the adhesive was determined by a HAAKE Rotary Viscometer whereas loop tack and shear strength were measured by a Llyod Adhesion Tester operating at 30 cm/min. Result shows that viscosity of the adhesive increases gradually with increase of silica loading due to the concentration effect of the filler. Both loop tack and shear strength show maximum value at 40 phr silica for ENR 25. However, the respective values for ENR 50 are 20 and 40 phr of filler. This observation is attributed to the maximum wettability and compatibility of adhesive on the substrate at the respective silica loadings. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of zinc oxide on the viscosity,tack, and peel strength of ENR 25‐based pressure‐sensitive adhesives

Viscosity, loop tack, and peel strength of epoxidized natural rubber (ENR 25 grade)‐based pressure‐sensitive adhesive was studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10–50 parts per hundred parts of rubber (phr). Coumarone–indene resin with loading from 20 to 100 phr was chosen as the tackifier resin. Toluene was used as the solvent throughout the experiment. The adhesive was coated on the substrate using a SHEEN hand coater to give a coating thickness of 60 μm. Viscosity of the adhesive was determined by a HAAKE Rotary Viscometer whereas the loop tack and peel strength were measured by a Llyod Adhesion Tester operating at 30 cm/min. Results show that viscosity and loop tack of adhesive increases with increasing zinc oxide concentration. For the peel strength, it increases with zinc oxide concentration up to 30–40 phr and drops after the maximum value. This observation is associated with the effect of varying degree of wettability of the adhesive on the substrate. However, for a fixed zinc oxide concentration, loop tack and peel strength exhibit maximum value at 80 phr resin loading after which both properties decrease with further addition of resin, an observation which is attributed to phase inversion. From this study, the optimum adhesion property is achieved by using 40 phr zinc oxide and 80 phr coumarone–indene resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Adhesion property of crosslinked epoxidized (natural rubber)/(acrylonitrile‐butadiene) rubber blend adhesives in the presence of petro resin tackifier

Loop tack, peel strength, shear strength, and morphology of (benzoyl peroxide)‐cured epoxidized natural rubber (ENR 25)/(acrylonitrile‐butadiene) rubber (NBR) blend adhesive were investigated by using petro resin as the tackifying resin. Benzoyl peroxide loading varied from 1 to 5 parts by weight per hundred parts of resin (phr), whereas the petro resin loading was fixed at 40 phr. A SHEEN hand coater was used to coat the adhesive on the polyethylene terephthalate substrate at 30 μm and 120 μm coating thicknesses. (ENR 25)/NBR adhesive was crosslinked at 80°C for 30 min prior to the determination of adhesion strength by a Lloyd adhesion tester operating at 10–60 cm/min. Results show that maximum loop tack and peel strength occur at 2 phr of benzoyl peroxide loading, whereby optimum cohesive and adhesive strength are obtained. However, shear strength increases with increasing benzoyl peroxide concentration, an observation that is associated with the steady increase in the cohesive strength. Scanning electron microscopy micrograph shows that little adhesive remained on the substrate at 0 phr compared with 2 phr of benzoyl peroxide loading, indicating that crosslinking increases the peel strength of the adhesive. In all cases, the adhesion properties increase with coating thickness and testing rate . J.VINYL ADDIT. TECHNOL., 24:93–98, 2018. © 2015 Society of Plastics Engineers     

The effect of particle size and composition on the performance of styrene/butyl acrylate miniemulsion-based PSAs

Styrene/butyl acrylate batch miniemulsion copolymerizations were performed in a 1.2 L stainless steel reactor. Conversions were monitored off-line using gravimetry and in-line using ATR-FTIR spectroscopy. The final latexes were coated on a polyethylene terephthalate carrier and dried at room temperature for 2 days. Their performance as pressure-sensitive adhesives (PSAs) was evaluated by measuring their tackiness, peel strength and shear strength. By using a constrained mixture design, the influence of particle size and copolymer composition was investigated. Particle size was found to be the most influential factor for both tack and peel strength models. Tack showed a concave upward trend whereas peel strength decreased with increasing particle size. Shear strength decreased with increasing particle size but was also significantly influenced by copolymer composition. The final forms of the models allowed 3D response surfaces to be built and an optimal adhesive performance region (highest combined tack, peel strength and shear strength) was located near the smallest particle diameter investigated with the highest styrene composition. The positive effect of smaller particles on every adhesive property relates to the tighter packing provided by smaller particles during the drying process, thus increasing the area of contact between the adhesive and the substrate.     

Emulsion-based pressure sensitive adhesives from conjugated linoleic acid/styrene/butyl acrylate terpolymers

Free radical emulsion terpolymerizations of conjugated linoleic acid (CLA), styrene (Sty), and butyl acrylate (BA) were performed at 80 °C. Terpolymers were characterized for composition, conversion, molecular weight and glass transition temperature, latexes were characterized for viscosity and particle size while adhesives were characterized for tack, peel strength, shear strength, storage modulus, loss modulus and tan delta. One impurity commonly found in CLA, oleic acid, was shown to influence the reaction kinetics significantly. Adhesive performance was tuned using divinylbenzene (DVB) crosslinker to keep the terpolymer molecular weight in a desired range. By using a constrained mixture design, the influence of terpolymer composition, chain transfer agent (CTA) concentration, DVB concentration, molecular weights, viscosity and particle size on tack, peel strength and shear strength was investigated. The final forms of the resulting empirical models allowed the creation of 3D response surfaces for pressure sensitive adhesive (PSA) performance optimization.     

Effect of N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine antioxidant on the adhesion properties of (zinc oxide)‐filled (epoxidized natural rubber 25)‐based pressure‐sensitive adhesives

The effect of antioxidant, namely, N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine (IPPD), on the adhesion properties of epoxidized natural rubber (ENR 25)‐based pressure‐sensitive adhesive was investigated. The concentration of the IPPD was varied from 0 to 5 parts by weight per hundred parts of rubber (phr). Coumarone‐indene resin, zinc oxide, toluene, and polyethylene terephthalate were used as the tackifier, filler, solvent, and substrate, respectively. A Lloyd Adhesion Tester operating at different testing rates (10–60 cm/min) was used to determine the loop tack, peel strength, and shear strength at 60‐µm and 120‐µm coating thicknesses. Results indicate that adhesion properties increase with IPPD up to 2 phr of content, after which it decreases with further addition of the antioxidant. This observation is attributed to the culmination of wettability and compatibility at the optimum IPPD concentration. The 60‐µm coated sample consistently shows higher adhesion strength than that of 120‐µm coated sample. Loop tack and peel strength increase with testing rate up to 30 cm/min. However, shear strength increases with increasing testing rate in the testing rate investigated in this study. J. VINYL ADDIT. TECHNOL., 21:111–115, 2015. © 2014 Society of Plastics Engineers     

Influence of Dioctyl Maleate Concentration on Performance Behavior of Water Based Pressure-sensitive Adhesives via Reversible Addition–Fragmentation Chain Transfer Emulsion Polymerization

Reversible addition–fragmentation chain transfer (RAFT)-mediated polymerization was successfully applied for the synthesis of pressure-sensitive adhesives (PSAs) of predetermined molar mass and of low polydispersity index (PDI). The performances of the adhesives were investigated by testing tack, peel, and shear resistance on seven different substrates (coated paper, uncoated paper, polyethylene terephthalate (PET), biaxially oriented polyethylene terephthalate (BOPP), aluminum strip, low linear density polyethylene (LLDPE), and low density polyethylene (LDPE). The influence of monomer composition on the adhesive performance was evaluated by varying the molar ratio of butyl acrylate (BA)/dioctyl maleate (DOM) while keeping the molar ratio of acrylic acid (AA) and 2-hydroxy ethyl acrylate (2-HEA) constant. As the DOM content increased, shear, peel strength, and loop tack were found to increase. It was noted that the adhesive properties of PSAs can be tailored by incorporating small amounts of hydrophobic DOM into the PSAs, which significantly increases the peel and shear strength of the resulting PSAs. Carboxyl terminated bifunctional trithiocarbonate RAFT agent possess the strong potential to polymerize hydrophobic DOM in aqueous phase and exhibit better living character with PDI less than 1.5.     

The effect of polymer molecular weight and crosslinking reactions on the adhesion properties of microsphere water-based acrylic pressure-sensitive adhesives

In this work, the effect of polymer molecular weight and crosslinking reactions on the end-use properties of the microsphere water-based acrylic pressure-sensitive adhesives (PSA) is presented. Polymer molecular weight and polymer microstructure were regulated using different chain transfer agent (CTA) concentrations and by addition of a diacrylic monomer (MM). The adhesion properties of the synthesized PSAs were characterized via measurements of tack, peel adhesion and shear strength. The results of experiments have shown that the kinetics of suspension polymerization is relatively independent on the amount of CTA and MM. The amount of gel phase in the adhesive was reduced with increasing amount of CTA agent, and gel phase amount may be considered as a function of polymer molecular weight. With a combination of CTA and MM was possible to regulate the amount of formed gel phase in the adhesive, as well sol phase molecular weight. All of the measured adhesion properties strongly depend on molecular weight of the synthesized polymer and on the amount of gel phase. For adhesives synthesized solely with addition of CTA, tack decreased with lower polymer molecular weight and consecutively also with lower amount of gel phase. The same trend was also observed for peel strength measurements, whereas a cohesive failure was observed for adhesives with low amount of gel phase. A maximum value for tack and shear strength was observed at 80 wt% of gel phase. In case of syntheses with a combination of CTA and MM (amount of gel phase in range from 70 to 80 wt%), tack values were distributed in quite narrow range. On the other hand, peel strength values decreased in comparison with adhesives synthesized only with CTA, regardless to the equal amount of gel phase. Poor shear strength was observed for all adhesives synthesized by combination of CTA and MM.     

Low corrosion optically clear adhesives for conducting glass: I. Effects of N,N‐diethylacrylamide and acrylic acid mixtures on optically clear adhesives

This study designs less corrosive optically clear adhesives (OCAs) with good rework properties, where copolymer and glycidyl methacrylate (GMA) are cured by ultraviolet to form OCAs. The copolymer are synthesized by using N,N‐diethylacrylamide (DMA), acrylic acid (AA), and 2‐ethylhexyl acrylate. The DMA and AA could form acid–base interaction and therefore lower the corrosion on metallic substrate caused by AA. Copolymer is applied in OCAs, as different adhesive properties are presented. In terms of the adhesive property of OCAs, the peel strength, shear strength, and transmittance property are decreased when the GMA concentration is increased. The tack and haze are enhanced accordingly. After 7 days' standing at 60 °C and 90% RH, OCAs have no obvious corrosion on the conductive glass circuits, and there is no residue after peeling off. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46277.     

Melt versus solvent coating: Structure and properties of block–copolymer‐based pressure‐sensitive adhesives

Pressure‐sensitive adhesives (PSAs) composed of a styrene–isoprene–styrene triblock copolymer and a midblock‐associating resin were prepared via solvent and hot‐melt coating. The formulations and thermal histories up to the point of coating were identical, yet significant differences in the properties were observed as a function of the coating method. The solvent‐coated PSA showed superior shear holding power, and the hot‐melt‐coated PSA performed better in tack and peel tests. Two factors resulting from the processing conditions were responsible for these property differences. The quick cooling process occurring after hot‐melt coating led to a poorly defined microstructure and, therefore, less physical crosslinking. Rheological data for melt‐pressed and solvent‐cast PSA films confirmed these microstructural differences. The increased solubility of the tackifier in the solvent additionally created a composition gradient in the solvent coating. Annealing improved the long‐range order of both hot‐melt and solvent coatings, producing a body‐centered cubic microstructure identified by small‐angle X‐ray scattering. This microstructure improved the shear strength of both types of adhesive coatings, whereas the peel and tack properties of the solvent coatings remained inferior to those of the hot‐melt coatings because of differences in the surface compositions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3355–3367, 2002     

Adhesion properties of (epoxidized natural rubber)/(ethylene‐propylene‐diene rubber) blend adhesive: Effect of blend ratio and testing rate

The adhesion properties of epoxidized natural rubber (ENR 25)/(ethylene‐propylene‐diene rubber) blend adhesive were investigated by using various blend ratios of the two rubbers and rate of testing. Coumarone‐indene resin was used as the tackifier. Results show that the loop tack and peel strength of adhesives increase steadily up to 60% ENR 25 before decreasing with further increase in % ENR 25. This observation is attributed to an increase in wettability and compatibility up to the optimum value of the ENR 25 blend ratio. However, shear strength increases continuously with increasing percentage of ENR 25, an observation that is ascribed to the increasing cohesive strength of the blend adhesive. In all cases, the adhesion properties increase with increasing coating thickness and testing rates. J. VINYL ADDIT. TECHNOL., 22:134–139, 2016. © 2014 Society of Plastics Engineers     

Effect of the MMA content on the emulsion polymerization process and adhesive properties of poly(BA‐co‐MMA‐co‐AA) latexes

In the past work, the shear resistance of pure poly(n‐butyl acrylate) was low, even incorporation of inorganic filler, silica in the composition. It is well‐known that the copolymerization of n‐butyl acrylate (BA) with methyl methacrylate (MMA) will increase the glass transition temperature, and enhance the shear resistance of acrylic polymers. In the current work, the preparation of a series of acrylic water‐borne pressure‐sensitive adhesives (PSAs) with the controlled composition and structure for the copolymerization of BA and acrylic acid (AA) with different MMA contents, poly(BA‐co‐MMA‐co‐AA) was reported and its effects on adhesive properties of the latices were investigated. The latices of poly(BA‐co‐MMA‐co‐AA) were prepared at a solid content of 50% by two‐stage sequential emulsion polymerization, and this process consisted of a batch seed stage giving a particle diameter of 111 nm, which was then grown by the semicontinuous addition of monomers to final diameter of 303 nm. Dynamic light scattering (DLS) was used to monitor the particle diameters and proved that no new nucleation occurred during the growth stage. Copolymerization of BA with MMA raised the glass transition temperature (T_g) of the soft acrylic polymers, and had the effect of improving shear resistance, while the loop tack and peel adhesion kept relatively high. The relationship between pressure‐sensitive properties and molecular parameters, such as gel content and molecular weight, was evaluated. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Peel and shear strength of pressure‐sensitive adhesives prepared from epoxidized natural rubber

Peel and shear strength of two grades of epoxidized natural rubber (ENR 25 and ENR 50)‐based pressure‐sensitive adhesive was studied. Coumarone‐indene resin was used as the tackifier, whereas toluene was chosen as the solvent throughout the experiment. The tackifier loading was varied from 0 to 80 parts per hundred parts of rubber (phr). A SHEEN hand coater was used to coat the adhesive on substrate to give a coating thickness of 30, 60, 90, and 120 μm. Peel strength and shear strength of the adhesive were determined by using a Lloyd adhesion tester and Texture analyzer, respectively. Results show that maximum peel strength occurs at 40 phr of coumarone‐indene resin for both ENRs studied an observation, which is attributed to the maximum wettability of the substrate. However, the shear strength shows a gradual decrease with increasing tackifier loading because of the decrease in cohesive strength of adhesive. ENR 25 consistently indicates higher peel strength and shear strength than ENR 50. Generally, peel and shear strength increases with coating thickness. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007.     

Effect of Barium Chloride Filler on the Adhesion Properties of Epoxidized Natural Rubber (ENR 25)-Based Adhesives

The adhesion properties of epoxidized natural rubber (ENR 25)-based adhesive were studied using barium chloride, coumarone-indene resin and toluene as the filler, tackifier and solvent respectively. Viscosity was determined by a Brookfield Viscometer whereas tack, shear and peel strength was measured by a Llyod Adhesion Tester. Results show that viscosity of adhesive increases gradually with increasing barium chloride loading. Loop tack, shear and peel strength indicates a maximum value at 10 parts per hundred parts of rubber (phr) of barium chloride, an observation that is attributed to the maximum wettability and compatibility of adhesive on the substrate.     

Shear,tack, and peel of polyisobutylene: Effect of molecular weight and molecular weight distribution

The effect of polymeric molecular weight and molecular weight distribution on pressure-sensitive adhesive performance was studied in a model system of commercial polyisobutylenes. Molecular weight was characterized by size exclusion chromatography and membrane osmometry. Pressure sensitive adhesive performance was assessed by shear, peel, and probe tack testing based on standardized test methods. Lower molecular weight polyisobutylenes (Mw < 600,000) are successful in peel and probe tack testing due to their ability to flow quickly and wet the substrate test surface. They do not function as well in shear, however, where the polymer must resist flow under a load. High molecular weight species, by contrast, perform well in shear resistance tests and less successfully in peel and probe tack testing. Where high and low molecular weight polyisobutylenes are blended to broaden the molecular weight distribution while maintaining constant weight average molecular weight, adhesive performance in shear, peel, and probe tack are improved. All of the adhesive properties tested were found to have their foundation in some fundamental rheological properties of the polymers (e.g., shear viscosity and tensile creep compliance). This suggests the use of fundamental rheological characterization for screening of adhesive formulations over more empirical adhesive testing methods.     

Effect of Blend Ratio and Testing Rate on the Adhesion Properties of Epoxidized Natural Rubber (ENR 25)/Styrene–Butadiene Rubber (SBR) Blend Adhesive

The effect of rubber blend ratio and testing rate on the adhesion properties of epoxidized natural rubber (ENR 25)/styrene–butadiene rubber (SBR) blend adhesive were studied using 40 parts per hundred parts of rubber (phr) of coumarone-indene resin as the tackifying resin. Toluene and poly(ethylene terephthalate) (PET) film were used as the solvent and substrate, respectively. A SHEEN hand coater was used to coat the adhesive on the PET substrate at 30, 60, 90, and 120 µm coating thickness. Viscosity was determined by a Brookfield viscometer whereas loop tack, peel strength, and shear strength were measured by a Llyod Adhesion Tester at various testing rates from 10 to 60 cm/min. Results show that viscosity increases gradually with % ENR 25. However, loop tack, peel strength, and shear strength of adhesives indicate a maximum value at 40% ENR 25, after which the adhesion properties decreases with further increase in % ENR 25. This observation is attributed to the varying degree of wettability which culminates at an optimum value of 40% ENR 25 blend ratio. In all cases, the adhesion properties increase with increasing coating thickness and rate of testing.