PSA Release Force Profiles from Silicone Liners: Probing Viscoelastic Contributions from Release System Components

Release force profiles of an acrylic- and rubber-based pressure sensitive adhesive (PSA) from silicone release coatings containing different levels of a high-release additive (HRA) were measured. The profiles of release force differed dramatically for the two different adhesive types. The general trends of either increasing or decreasing release force profiles with peel rate were predominantly attributed to the relative ability of the adhesive component to dissipate and store energy (i.e., tan δ) over the operating frequency range. The addition of HRA enhanced the dissipative character (G' and tan δ increased) of the release coating which resulted in higher release forces. An empirical model based on the viscoelastic properties of the adhesive and release coating was proposed to describe release force profiles and initial estimates for the fitting parameters were determined. The release model was shown to predict successfully the impact of adhesive thickness on the release force profile using an acrylic PSA which was not used for the model development. Some evidence was also obtained for the validity in omitting the contributions of the elastic backing components from the model.     

PSA Release Force Profiles from Silicone Liners: Probing Viscoelastic Contributions from Release System Components

Release force profiles of an acrylic- and rubber-based pressure sensitive adhesive (PSA) from silicone release coatings containing different levels of a high-release additive (HRA) were measured. The profiles of release force differed dramatically for the two different adhesive types. The general trends of either increasing or decreasing release force profiles with peel rate were predominantly attributed to the relative ability of the adhesive component to dissipate and store energy (i.e., tan δ) over the operating frequency range. The addition of HRA enhanced the dissipative character (G″ and tan δ increased) of the release coating which resulted in higher release forces. An empirical model based on the viscoelastic properties of the adhesive and release coating was proposed to describe release force profiles and initial estimates for the fitting parameters were determined. The release model was shown to predict successfully the impact of adhesive thickness on the release force profile using an acrylic PSA which was not used for the model development. Some evidence was also obtained for the validity in omitting the contributions of the elastic backing components from the model.     

A review and comparative study of release coatings for optimised abhesion in resin transfer moulding applications

In this study, a number of abhesion-promoting coatings were considered in terms of their physicochemical and release properties. The techniques used to further this study include; field emission gun scanning electron microscopy, atomic force microscopy (AFM), profilometry, X-ray photoelectron spectroscopy, Auger electron spectroscopy, static secondary ion mass spectrometry, Fourier transform infra-red analysis and contact angle analysis for coating physical and chemical characterisation along with pulsed force mode atomic force microscopy (PF-AFM) and other adhesion and mechanical tests to determine surface release properties. These coatings were applied to metal substrates and were based upon silicone, fluoropolymer or metal–PTFE composite chemistry, all being potentially useful as release films for resin transfer moulding applications. The semi-permanent Frekote B15/710 NC mould release coating system, which is based on PDMS, proved extremely effective in terms of release against a cured epoxide applied under pressure. Although fluoroalkylsilane coatings offer a number of technological advantages for release applications, they generally produce very thin coatings which conform to any existing surface topography and adhesion through mechanical interlocking. The commercial PTFE-based coatings were found to provide poor release properties due to the presence of surface microcracks which allowed epoxide penetration when cured under elevated pressure and temperature. Electroless Ni/PTFE composite coatings comprise a hard nickel–phosphorus matrix containing a very fine dispersion of PTFE particles. The matrix proved sufficiently robust for industrial applications and the low friction and surface energy provided by the embedded PTFE combined with macroscopic-scale surface roughness provided efficient mould release.     

有机硅树脂在粉末涂料中的改性作用及应用进展

综述了近年来国内外有机硅树脂在粉末涂料中的应用研究进展。讨论了有机硅树脂与有机树脂通过共混、化学结合作为粉末涂料基材以及互为固化剂等不同改性方式的特点。有机硅组分的引入可以改善和提高粉末涂料涂膜性能 ,特别是耐候性及耐热性能。展望了有机硅改性树脂在粉末涂料中的应用和发展前景。     

纳米二氧化硅-有机硅复合涂层防护性能的研究

利用电化学阻抗谱(EIS)技术对纳米二氧化硅含量为5%的有机硅复合涂层的防护性能进行了研究,试验结果与有机硅清漆涂层和微米二氧化硅含量为5%的有机硅复合涂层的实验结果进行了比较。结果表明,纳米氧化硅粒子的填加有效的阻挡侵蚀介质的渗透和腐蚀,纳米氧化硅-有机硅复合涂层比有机硅清漆涂层和微米二氧化硅-有机硅复合涂层具有更好的防护性能。     

Advances in environmentally benign coatings and adhesives

There is an increased need to develop environmentally benign (no pollution or release of hazardous materials into the air, water or soil from a coating or adhesive either during their manufacture, use and disposal or recycle lifetimes), coatings and adhesives that have equivalent or superior properties to their conventional (non-environmentally benign) counterparts. This paper discusses some of the new concepts or technologies associated with environmentally benign barrier coatings for packaging, abrasion resistant coatings for plastic substrates, new developments in wood finishes, antifouling coatings and new chemistry associated with the design of advanced coating systems. This paper also discusses how Battelle is helping the US Air Force to eliminate hazardous waste associated with structural adhesive technology through the identification of equivalent adhesive systems reducing the number of adhesives used to repair current aircraft and missile equipment. This paper also discusses advances in the area of repulpable/recyclable pressure sensitive adhesives and silicone release coatings used in a variety of commercial applications.     

Effects of pigmentation on siloxane–polyurethane coatings and their performance as fouling-release marine coatings

Siloxane–polyurethane paints were formulated and characterized for coating properties and performance as fouling-release (FR) marine coatings. Paints were formulated at 20 and 30 pigment volume concentrations with titanium dioxide, and aminopropyl-terminated poly(dimethylsiloxane) (APT-PDMS) loadings were varied from 0 to 30% based on binder mass. The coatings were characterized for water contact angle, surface energy (SE), gloss, and pseudobarnacle (PB) adhesion. The assessment of the FR performance compared with polyurethane (PU) and silicone standards through the use of laboratory biological assays was also performed. Biofilm retention and adhesion were conducted with the marine bacterium Cellulophaga lytica, and the microalgae diatom Navicula incerta. Live adult barnacle reattachment using Amphibalanus amphitrite was also performed. The pigmented coatings were found to have properties and FR performance similar to those prepared without pigment. However, a higher loading of PDMS was required, in some cases, to obtain the same properties as coatings prepared without pigment. These coatings rely on a self-stratification mechanism to bring the PDMS to the coating surface. The slight reduction in water contact angle (WCA) and increase in pseudobarnacle release force with pigmentation suggests that pigmentation slowed or interfered with the self-stratification mechanism. However, increasing the PDMS loading is an apparent method for overcoming this issue, allowing for coatings having similar properties as those of clear coatings and FR performance similar to those of silicone standard coatings.     

Vi‐PDMS incorporated with protein‐based coatings designed for permeability‐enhanced applications

Functional polydimethylsiloxanes containing vinyl groups (Vi‐PDMS) were used for silicone‐based organic polymers in composites and adhesive formulations. Poly(butyl acrylate/methyl methacrylate/vinyl silicone oil)/casein–caprolactam [P(BA‐MMA‐Vi‐PDMS)/CA‐CPL] nanoparticles were prepared via emulsifier‐free polymerization. The well‐defined core–shell structure of P(BA‐MMA‐Vi‐PDMS)/CA‐CPL nanoparticles was verified by transmission electron microscopy. The results of scanning electron microscopy and contact angle measurements proved that the as‐obtained coatings exhibited porous and hydrophobic properties, which were helpful for superior water vapor permeability. By comparing the appearance of the coatings before and after adhesion analysis, the excellent adhesion strength was proved to be dominated by Vi‐PDMS. The relationship between interface morphology and properties of the resultant coatings was investigated in detail. The nucleation mechanism for this soap‐free emulsion synthesis was also proposed accordingly. These results could help in designing coatings with better surface properties and wider application. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46501.     

ESCA Studies of Silicone Release Coatings

X-ray photoelectron spectroscopy (XPS or ESCA) has been used to examine the surfaces of silicone release coatings to shed light on phenomena not adequately addressed by our previous contact angle studies. In most cases, the surface composition of the coatings corresponds to pure polydimethylsiloxane. Other components of the coatings, e.g. the emulsifier in the emulsion-based material, are not detected by ESCA. The differences in surface tension between the coatings must be due to other factors, possibly different surface morphologies or low molecular weight constituents that are removed in the high vacuum environment of the ESCA experiment. Delamination has little effect on the surface composition of the silicone coatings but some transfer of silicone to the adhesive occurs in all cases during the release process. The amount transferred increases as the crosslink density of the coating decreases. However, the release force also increases suggesting that bulk effects are more important than surface effects.     

粉末涂料用耐高温有机硅改性聚酯树脂的制备和性能研究

通过化学共聚改性的方法在粉末涂料聚酯树脂中引入有机硅,合成了粉末涂料用有机硅改性聚酯树脂,研究了有机硅中间体用量对改性聚酯树脂黏度、相对分子质量及其分布、玻璃化转变温度和热失质量的影响。并用其制备了平面和消光 2种粉末涂料,研究了不同有机硅中间体加量对涂层性能的影响。结果表明：有机硅中间体加量为 42%的改性聚酯树脂具有合适的玻璃化转变温度和黏度,制备的粉末涂层具有良好的附着力;在 350℃左右的高温下平面涂层具有优秀的保光率,加入云母粉的消光涂层则具有更好的弯曲性能。有机硅改性聚酯树脂在兼顾耐热性和平面高光的同时,又解决了使用纯有机硅树脂的价格偏高的问题,为市场提供了耐高温粉末涂料用聚酯树脂的更多选择性。     

活性溶剂涂料及其未来发展

活性溶剂涂料指其溶剂最终成为涂膜组成,在固化成膜过程中不向大气排放VOC。文中介绍了丙烯酸树脂、多异氰酸酯、聚脲涂料、无溶剂涂料、改性环氧树脂涂料和有机硅涂料产品。     

Removal of Pseudobarnacles (epoxy) from silicone coatings with a thickness gradient due to an applied transverse force

One of the uses for silicone coatings is as foul release coatings on ship hulls. Most studies on silicone coating's release behavior have focused on coatings with uniform thickness. These studies have shown that the force required to remove pseudobarnacles, modeled as epoxy studs, from thin silicone coatings decreases as the thickness increases. Two types of release mechanisms were observed: void formation and edge peeling. In previous work, pull-off tests were performed on epoxy from clear silicone coatings with a thickness gradient on glass substrates. The presence of a thickness gradient introduced a third type of release behavior—fingering. Also present was a mixed mode of release involving void formation or fingering with peeling. For the shear tests described in this study, release of the epoxy from the silicone initiated at the point of load application then proceeded around the circumference of the stud regardless of the direction of the applied force. The final release from the coating started predominately from the thin section of the coating and proceeded to the thick section, again for both loading directions.     

Preparation and properties of crosslinked network coatings based on perfluoropolyether/poly(dimethyl siloxane)/acrylic polyols for marine fouling–release applications

α,ω‐Triethoxysilane terminated poly(dimethyl siloxane) (PDMS) oligomer, α,ω‐triethoxysilane terminated perfluoropolyether (PFPE) oligomer, and acrylic polyols were first synthesized via an addition reaction and free‐radical polymerization. Then, crosslinked network coatings based on PFPE/PDMS/acrylic polyols for marine fouling‐release applications were prepared by a condensation reaction. The structure of the crosslinked network coating was characterized by Fourier transform infrared spectroscopy. The chemical composition of the coating surface was characterized by X‐ray photoelectron spectroscopy. The thermal properties, surface energy, mechanical properties, adhesion, and antiseawater immersion performance of the coatings were systematically studied. The antibiofouling properties of the crosslinked network coating were evaluated by laboratory biofouling assays with the bacteria Escherichia coli and the fouling diatom Navicula. The results from the preliminary study suggested that this crosslinked network coating had good adhesion and promising antifouling properties that were comparable to a silicone standard. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41860.     

环氧改性有机硅树脂的应用研究

以不同环氧改性有机硅树脂作为基料树脂,研究了不同树脂对漆膜性能的影响;通过选用不同固化体系对漆膜机械性能和耐热性做了比较;同时研究了环氧改性有机硅树脂与有机硅树脂的混溶性及影响;分别研究了该树脂配制的底、中、面涂层的常规性能及复合涂层的机械性能。同时对不同固化剂的影响和不同树脂的影响做了TG和DSC分析,结果表明,环氧改性有机硅树脂耐温性能较环氧树脂有较明显的提高,基本可用于高温涂料;环氧改性有机硅树脂可与纯有机硅树脂复配,有望形成具有更高耐温性能的涂膜。并且可通过复合固化剂的选用达到更佳的耐温性能和较好的物理机械性能。     

A durable and environmental friendly superhydrophobic coatings with self-cleaning,anti-fouling performance for liquid-food residue reduction

A durable and environmentally-friendly superhydrophobic coatings for liquid-food residue reduction were prepared by using stearic acid (SA) modified organic montmorillonite (SA@OMMT) and poly(dimethylsiloxane) (PDMS). Due to the natural hydrophobicity of SAs, SA@OMMT provides low surface energy as well as roughness for the coating. PDMS not only provided low surface energy in the coating but also contributed to the bonding of SA@OMMT as a result of its high adhesive properties. In addition, PDMS has good physical properties after curing, which can effectively improve the physical properties and durability of a superhydrophobic coating by the self-assembly method using a PDMS/n-hexane solution. For 1 wt.% SA@OMMT and 5 wt.% PDMS, the resulting SA@OMMT/PDMS (SOP) coating showed the water contact angle (WCA) and water sliding angle (WSA) of 156.3°and 2°, respectively. The prepared coatings have good physical and chemical stability, and they still have superhydrophobicity after physical abrasion tests and exposure to the corrosion solutions. In the meanwhile, the prepared coating also has flexibility and superhydrophobicity after bending and folding. Finally, the coating surface shows highly effective antifouling ability to liquid and solid pollutants. The coating can be applied against different substrates and has potential application in the field of liquid-food residue reduction.     

Investigation of adhesion phenomena in thermoplastic polyurethane injection molding process

Adhesion is a serious problem when ejecting products from mold cavities in the injection molding process. This study developed a mechanism for measuring adhesion force in injection molding process. The apparatus measured and quantified adhesion force and engineers could use the measurements to understand the effectiveness of mold release agent and different adhesion release coatings. Three different surface roughness conditions (Ra = 0.01, 0.08, and 1.20 μm) without surface coating were compared and the results showed that the smallest adhesion force would be obtained when Ra = 0.08 μm. With Ra = 0.08 μm and 0.01 μm, it was found that single‐layer CrN (chromium nitride) coating and modified CrN coating were effective in alleviating adhesion force whereas multi‐layer CrN coating was not effective. In addition, the adhesion force was proportional to the ejection speed, melting temperature, and cooling time. Because thermoplastic polyurethane (TPU) behaves like a rubber‐like material and is thus different from other stiff resin after cooling, the release of adhesion of TPU is time‐dependent. Comparing the peak and integrated impulse values of the measured curve in continuous experiment, it was found that these two results were in good agreement with each other. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Effect of a marine bacterial biofilm on adhesion and retention of pseudo barnacle to silicone coating surface

The effect of a marine bacterial Cytophaga lytica (C. lytica) biofilm on the adhesion and retention of a pseudobarnacle (epoxy adhesive) to platinum-cured silicone coatings was investigated at varying coating thickness (100–800 μm), modulus (E=0.08–1.3 MPa), and shear rate (2–22 μm/s). The initial adhesion of C. lytica biofilm on the silicone coating surfaces was increased as the coating modulus was increased. Nonetheless, the adhesion strength of the pseudobarnacle was not significantly influenced by the attached biofilms, with its strength decreasing with increasing the coating modulus. Thus, these results suggest that the pseudobarnacle adhesion strength would be primarily determined by physico-mechanical properties of the silicone coatings. Also, the adhesion/detachment tests demonstrated that the retention of the pseudobarnacle after water jetting was minimal for the soft silicone coating (VP1), which showed better performance than the widely acceptable silicone resin of DC 3140.     

Mechanical and dielectric properties of short‐carbon‐fibers/epoxy‐modified‐organic‐silicone‐resin as heat resistant microwave absorbing coatings

Heat resistant microwave absorbing coatings were prepared by brushing and thereafter heat treatment, using epoxy modified organic silicone resin as binding material, short carbon fibers (C_sf) as absorbers, talcum powder and glass powder as filling materials. The mechanical and dielectric properties of the coatings before and after heat treatment at 600°C for 10 mins were studied. The results showed that the adhesive power after heat treatment enhances remarkably, both the real (ε′) and imaginary (ε″) parts of the permittivity of the coatings increase with increasing C_sf content in the frequency range of 8.2–12.4 GHz. The calculation value of the reflection loss as single layer absorber indicates that epoxy modified organic silicone resin coatings containing short carbon fibers could be a promising radar absorbing material applied at high temperature. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1392‐1398, 2013     

纳米SiO2改性硅树脂天线罩涂层性能测试

随着现代导弹技术的快速发展,石英陶瓷天线罩得到广泛应用,但因其自身的易吸潮、耐污差等缺点,性能优异的天线罩防潮涂料的研制显得至关重要。本文通过对现有硅树脂进行改性制备了纳米SiO_2改性硅树脂涂层,并进行了相关性能测试分析。测试表明。改性后的硅树脂涂层吸水率明显下降,电性能优异,比现有纯硅树脂涂料硬度更高,耐热性更好。     

Effect of solubility and miscibility on the adhesion behavior of polymer‐coated carbon fibers with vinyl ester resins

Interfacial shear strength (IFSS) of carbon fibers with vinyl ester resin was investigated as a function of the structure of the polymer coating on carbon fibers via microdroplet tests. For coating carbon fibers, high‐performance polymers such as poly(arylene ether phosphine oxide) (PEPO), Udel® P‐1700, and Ultem® 1000, water‐soluble poly(hydroxy ether ethanol amine) (PHEA), water‐dispersed carboxy‐modified poly(hydroxy ether) (C‐PHE), and water‐insoluble poly(hydroxy ether) (PHE) were utilized. Adhesion of polymers to carbon fibers was also evaluated and the failure surface of the fibers was analyzed by SEM to understand the adhesion mechanism. Diffusion between polymers and vinyl ester resins was investigated and the solubility parameters of the polymers were calculated, with the results being correlated to the IFSS. A highly enhanced IFSS was obtained with PEPO coating, while marginally improved IFSS resulted from PHE, Udel®, and C‐PHE coatings. However, PHEA and Ultem® coatings showed no improvement. Such results were attributed to the extent of solubility and/or miscibility of polymer coatings in vinyl ester resin, with better solubility and miscibility leading to a higher IFSS. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1042–1053, 2001