Control of adhesive properties through structured particle design of water-borne pressure-sensitive adhesives

The concept of using structured particles and the mechanism of film formation from latexes to produce pressure-sensitive adhesive (PSA) films with controlled sub-micron and nanometre scale morphology has been investigated with the objective of enhancing adhesive performance. Structured particle acrylate-based latexes were synthesised by seeded semi-continuous emulsion polymerisation procedures. Aliquots removed at intervals during the polymerisations were analysed for conversion and z-average particle diameter; the results confirm that the particles grew without secondary nucleation or coagulation. Three-layer particles were studied first and comprised a core whose composition was the same for all particles, an interlayer between core and shell which was crosslinked during synthesis (using 1,6-hexanediol diacrylate, HDDA) and a shell which contained diacetone acrylamide (DAAM) repeat units that provided for interfacial crosslinking between particles during film formation by reaction with post-added adipic acid dihydrazide (ADH). The three-layer latexes produced adhesive films with high shear resistance when ADH was added, but peel adhesion was generally low and further reduced by increasing either the thickness or HDDA concentration of the interlayer. Thus two-layer latexes with shell layers containing DAAM but no pre-crosslinked interlayer were the main focus of the study. The effects of core:shell ratio and amount of DAAM on adhesive performance were optimum with a core:shell ratio of 80:20 and 2 wt% DAAM in the shell copolymer, for which interfacial crosslinking using the stoichiometric amount of ADH led to a marked increase in shear resistance with only a slight reduction in peel adhesion. Increasing the level of n-dodecylmercaptan (DDM) chain transfer agent used in synthesis of the core increases peel adhesion and reduces shear resistance in the absence of ADH, but high shear resistance can be recovered through interfacial crosslinking with ADH. Adhesive performance can be optimised by using a high DDM level in the core and a low DDM level in the shell, a combination that enables both high peel adhesion and shear resistance to be achieved with the addition of ADH. The results from this study define guiding principles for development of commercial water-borne PSAs that can compete with solvent-borne PSAs in high-performance applications.     

Manipulation of chain transfer agent and cross-linker concentration to modify the performance of fluorinated acrylate latex pressure sensitive adhesive

Abstract

n-Dodecyl mercaptan (DDM) chain transfer agent and 1,6-hexanediol diacrylate (HDDA) cross-linker were used to manipulate latex properties in a monomer-starved seeded semi-continuous emulsion polymerization of butyl acrylate (BA), fluorine monomer dodecafluoroheptyl methacrylate (DFMA) together with acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA). The influences of both DDM and HDDA on the particle size of the latex, as well as on the gel content, thermostability (differential scanning calorimeter and thermal gravimetric analysis), surface properties (X-ray photoelectron spectra (XPS), contact angle analysis and atomic force microscopy), and viscoelasticity (N,N-dimethylacrylamide) of the polymer films were investigated. The results showed that the introduction of DDM and HDDA has no significant effects on the final particle size of the fluorinated pressure-sensitive adhesives (PSA) latexes. XPS analysis indicated that the fluoroalkyl groups had the tendency to enrich on the surface of the film. However, this enrichment of fluorine on the film surface was reduced after the introduction of HDDA, while increased with the addition of DDM. It was also found that the gel content, glass transition temperature (T_g), thermal stability, surface roughness, and modulus (G′, G?) of the fluorinated latex PSA were all increased with the introduction of HDDA. Nevertheless, opposite trends were observed for the latex after the addition of DDM. Finally, the effects of DDM and HDDA on the adhesive properties (i.e. loop tack, peel strength and shear strength) of the fluorinated latex PSA were also evaluated.     

氨基甲酸酯丙烯酸酯的合成及其光固化性能

利用碳酸亚乙酯与1,6-己二胺、异佛尔酮二胺反应合成了含氨基甲酸酯二元醇,并由氨基甲酸酯二元醇与丙二酸二甲酯的酯交换反应合成了丙二酸酯封端的氨基甲酸酯。利用丙二酸酯封端的氨基甲酸酯与1,6-己二醇二丙烯酸酯(HDDA)、1,3-新戊二醇二丙烯酸酯(NPGDA)及聚乙二醇二丙烯酸酯(PEG200DA)的Michael加成反应合成含多官能度氨基甲酸酯丙烯酸酯(NIPUs)。用1HNMR及HRMS表征了合成中间体及NIPUs的结构,用FTIR考察了NIPUs光固化过程,初步评价了合成的多官能度丙烯酸酯复配物的光固化膜性能。结果表明,含占总质量分数3 %的光引发剂1173及占总质量分数10 % HDDA的多官能度丙烯酸酯溶液均能在60 s内光固化形成表面平整、具有较好的柔韧性（0.5~2.0 mm）的膜,固化膜的凝胶率大于96 %,固化膜对玻璃的附着力为0~2级,HDDA及NPGDA基的氨基甲酸酯丙烯酸酯光固化膜的铅笔硬度均达到6 H。     

季铵盐改性丙烯酸酯抗静电剂合成及UV固化性能

本文采用甲基丙烯酸β羟乙酯(HEMA)、异佛尔酮二异氰酸酯(IPDI)及自制的N,N,N三乙基2羟乙基氯化铵合成了一种季铵盐改性丙烯酸酯抗静电剂。使用核磁共振谱表征产物结构。将产物制成浓度40%的甲基丙烯酸β羟乙酯(HEMA)溶液,通过UV固化成膜,涂膜的表面电阻为106Ω,水洗后表面电阻为107Ω。为了得到综合性能优异的涂膜,添加活性稀释剂1,6己二醇二丙烯酸酯(HDDA)与低聚物(PUA),研究了各组分对固化时间、硬度、附着力以及抗静电性的影响。最佳配比(质量分数):季铵盐改性丙烯酸酯抗静电剂40%,HEMA40%,HDDA15%,PUA5%。涂膜的性能:外观(目测)澄清透明,固化时间3s,硬度2H,附着力1级,表面电阻108Ω。     

Investigation for surface morphology variation of monodisperse polymer particle

Monodisperse polymer particles composed of polystyrene (PS) and poly(1,6‐hexanedioldiacrylate) were prepared via one‐step seeded polymerization using PS as seed particles. For the study, the effects of the molecular weight of seed polymer particles, the ratio of the absorbed hexanediol dimethacrylate (HDDA) to the seed polymer particles (swelling ratio), and the seeded polymerization rate on the surface morphology of poly(St‐HDDA) particles were investigated. It was observed that the crater‐shaped defect was at the surface of poly(St‐HDDA) particles, independent of the molecular weight of seed polymer, and swelling ratio. But its surface morphology could be controlled by changing the rate of the seeded polymerization. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2385–2394, 2007     

Influence of structural parameters on the degradation of ultrahigh‐molecular‐weight vinyl‐type network‐polymer precursors during elution through size exclusion chromatography columns

Network‐polymer precursors obtained in various crosslinking monovinyl/divinyl copolymerization systems, including benzyl methacrylate/1,6‐hexanediol dimethacrylate, benzyl acrylate (BzA)/1,6‐hexanediol diacrylate (HDDA), and vinyl benzoate/divinyl adipate, were subjected to degradation during elution through size exclusion chromatography (SEC) columns, although the copolymerizations were conducted under specified conditions where the factors for the greatly delayed gelation from the Flory–Stockmayer gelation theory were reduced. The most remarkable degradation was observed for the BzA/HDDA copolymerization, which provided prepolymers with the most flexible backbone chains. Thus, the BzA/HDDA precopolymers were chosen, and their degradation behavior during elution through SEC columns was explored in detail as one of the representatives of vinyl‐type network‐polymer precursors. The results were correlated with the structural parameters of network‐polymer precursors, including primary polymer chain length, branched structure, and multiple crosslink or network structure. The degradation became more remarkable with decreased primary polymer chain length, that is, the increment of branching, whereas reduced degradation was observed with the incorporation of loop and network structures into the prepolymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 577–582, 2003     

高硅含量有机无机杂化乳液的制备和溶胶-凝胶驱使成膜

A novel polymer/SiO2 hybrid emulsion (PAES) was prepared by directly mixing colloidal silica with polyacrylate emulsion (PAE) modified by a saline coupling agent. The sol-gel-derived thin films were obtained by addition of co-solvents into the PAES. The effects of γ-methacryloxypropyltrimethoxysilane (KH-570) content and co-solvent on the properties of PAES films were investigated. Dynamic laser scattering (DLS) data indicate that the average diameter of PAES (96 nm) is slightly larger than that of PAE (89 nm). Transmission electron microscopy (TEM) photo discloses that colloidal silica particles are dispersed uniformly around polyacrylate particles and some of the colloidal silica particles are adsorbed on the surface of PAE particles. The crosslinking degree data and Fourier transform infrared (FT-IR) spectra confirm that the chemical structure of the PAES is changed to form Si-O-Si-polymer crosslinking networks during the film formation. Atomic force microscope (AFM) photos show the solvent induced sol-gel process of colloidal silica and the Si-based polymer distribution on the film surface of the dried PAES. Thermogravimetric analysis (TGA) curves demonstrate that the PAES films display much better thermal stability than PAE.     

Coating characteristics of electron beam cured bisphenol A diglycidyl ether diacrylate resin containing 1,6-hexanediol diacrylate on wood surface

Electron beam curing of bisphenol A diglycidyl ether diacrylate resin (BDGDA) mixed with varying amount of 1,6-hexanediol diacrylate monomer (HDDA) was investigated using low energy DC electron beam accelerator. Cured coating films were analyzed by Fourier transformed infrared spectroscopy (FTIR), gel fraction, swelling ratio and thermogravimetric (TG) techniques. The wood surfaces cured with different coating compositions were tested for their end use performance properties like gloss, pencil hardness, scratch resistance, mar resistance, abrasion resistance, chemical resistance, steam resistance and cigarette burn resistance. FTIR studies indicated that the density of acrylate functionality and degree of curing increased with the HDDA content in the feed mixture. This observation was supported by gel fraction and swelling studies as well. The thermal stability, pencil hardness, mar resistance, abrasion resistance and solvent resistance properties of coating were observed to improve with the incorporation of HDDA. However, there was significant decrease in gloss and scratch resistance at higher HDDA content. The coating showed excellent steam and stain resistance but poor resistance to cigarette burns.     

Synthesis of bis[(4-hydroxyethoxy)phenyl]sulfone containing urethane acrylates and their applications

UV-curing processes are used in industrial applications because of their advantages such as high speed applications and solvent-free formulations at ambient temperature. UV-curable sulfone containing polyurethane acrylates were synthesized from bis[(4-hydroxyethoxy)phenyl]sulfone (BHEPS), polyols, isophorone diisocyanate (IPDI) and 2-hydroxyethyl methacrylate (HEMA). The polyurethane acrylates characterized with ¹H NMR and FT-IR spectroscopies. The UV-cured coatings and films were formulated with polyurethane acrylates, reactive diluents such as dipropyleneglycol diacrylate (DPGDA), 1,6-hexanediol diacrylate (HDDA) and photoinitiator. The water wettability of the UV-cured films was investigated by measuring contact angle. Sulfone containing polyurethane acrylates increase mechanical properties such as pendulum hardness, pencil hardness, tensile strength, and e-modulus values. These mechanical properties and chemical-solvent resistance may have been strongly dependant on the sulfone content and crosslinking density.     

Investigation on multifunctional monomer modified polypropylene and its foamability

1,6‐Hexanediol diacrylate (HDDA), pentaerythrithyl tetramethacrylate (PETMA), and triallyl‐isocyanurate (TAIC) were used as representative monomers to modify polypropylene (PP) in the presence of dicumyl peroxide (DCP) in a mixer. Fourier transformed infrared spectroscopy (FTIR) results confirmed that all the three polyfunctional monomers have been grafted on PP backbone. The shape of torque curves suggested the occurrence of grafting and/or crosslinking structure. The rheological behaviors of HDDA modified PP showed the highest G′ and lowest tan δ at low frequency, shear‐thinning shifted to lower frequency in η*–ω plot, as well as more deviation from semicircle characteristic of linear PP at high viscosity in Cole–Cole plot. And, the improvement of the mechanical properties followed the order as below: TAIC < PETMA < HDDA. Meanwhile, the foamability of the modified PP samples was also investigated. The cellular structure and morphology of the obtained foams were observed by scanning electron microscopy (SEM), and the results indicated that the foamability of the three modified PPs followed the same order, demonstrating HDDA modified PP foam possessed the highest cell density and expansion ratio, and the most well‐defined closed cell structure and uniformly cellular morphology. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1675–1681, 2013     

活性单体对超支化聚氨酯丙烯酸酯的影响

研究了活性单体种类及用量对超支化聚氨酯丙烯酸酯(HBUA)光固化膜机械性能的影响,并用光差扫描量热法(Photo-DSC)对超支化聚氨酯丙烯酸酯的光聚合反应速率进行了研究.结果表明,己二醇二丙烯酸酯(HDDA)比三羟甲基丙烷三丙烯酸酯(TMPTA)能更好地调节HBUA固化膜的综合性能,并促进UV固化反应的进行.HDDA的适宜质量分数为20%.     

A Novel Polymeric Adsorbent for Water and Dye Uptake: Acrylamide/Sodium Acrylate Copolymers and Semi-Interpenetrating Polymer Networks Composed of Gelatin and/or PVA

Gelatin (GEL) and poly (vinyl alcohol) (PVA)-based semi-interpenetrating polymer network (semi-IPN) hydrogels were prepared for cationic dye sorption. Chemically cross-linked copolymer of acrylamide/sodium acrylate (AAm/SA) with PVA and/or GEL were prepared by polymerization of aqueous solution of AAm, and SA using ammonium persulphate/N,N,N’,N’-tetramethylethylenediamine as redox initiating pair in presence of poly(ethylene glycol)diacrylate as cross-linker. FTIR analysis was used for structural characterization. Surface morphology was characterized by SEM. Methyl violet has been used in sorption studies. Water uptake, and dye sorption properties of the cross-linked polymeric systems were investigated as a function of chemical composition of the hydrogels.     

Application of an Electric Field for the Reduction of Particle and Colloidal Membrane Fouling in Crossflow Microfiltration

Abstract

In crossflow microfiltration applications, the solution to be treated is generally made up of a wide range of particles and colloids. The presence of colloids complicates this process due to its intrinsic characteristics such as high surface charge, high stability, high specific surface area, and relative small size in comparison to the membrane pores. This permits them to create a film of colloids on the external and internal membrane surface due to the interfacial phenomenon effects (electrokinetic and adsorption). This colloidal fouling plays a significant role in increasing the resistance to the filtration flux in comparison to the external membrane fouling created only by the panicles. The application of an electric field helps to reduce the membrane fouling due to colloids and particles, and thus results in an eventual improvement of the filtration flux.     

Preparation and evaluation of epoxy methacrylate UV‐curable coatings containing phthalazinone

Epoxy methacrylate resin (EMA) UV‐curable coatings exhibit high reactivity, low viscosity and excellent chemical resistance in environmentally friendly coatings. A novel EMA containing phthalazinone moieties for high temperature resistant UV‐curable coatings was synthesized. The formulations were cured with hexanediol diacrylate (HDDA) and trimethylol propane triacrylate (TMPTA) as reactive diluents promoted by a photoinitiator, and then interpenetrating polymer networks were generated. The mechanical, chemical and thermal properties of the clear coatings were characterized using Chinese National Standard methods (GB). EMA was used with UV radiation curing in combination with 6.7 wt% of HDDA and 13.4 wt% of TMPTA, and the properties of the cured films were as follows: pencil hardness of 5 H, 30% NaOH resistance for 30 days, 15% HCl resistance for 10 days, 3% NaCl resistance for 30 days and 5% weight loss temperature of 300.5 °C. EMA UV‐curable coatings containing phthalazinone exhibit excellent chemical and thermal stability, and could be potential candidates for UV‐curable zero volatile organic compound coatings applied in the fields of salt spray corrosion, strong radiation and high‐temperature resistance. Copyright © 2009 Society of Chemical Industry     

新型UV固化木器涂料的合成及性能研究

乙醇为溶剂,偶氮二异丁腈(AIBN)为引发剂,引发邻苯二甲酸二烯丙酯(DAP)聚合.聚合工艺为饥饿滴加法加入反应原料DAP、乙醇、AIBN,反应温度为85℃,反应时间约4 h.反应收率约34%,聚合物是可溶的预聚体.预聚体的凝胶色谱、红外光谱图及碘值都显示其具备进一步交联固化的潜力.然后,以合成的邻苯二甲酸二烯丙酯预聚...     

Poly(vinyl acetate)/polyacrylate semi‐interpenetrating polymer networks. II. Thermal,mechanical, and morphological characterization

The thermal, dynamic mechanical, and mechanical properties and morphology of two series of semi‐interpenetrating polymer networks (s‐IPNs) based on linear poly(vinyl acetate) (PVAc) and a crosslinked n‐butyl acrylate/1,6‐hexanediol diacrylate copolymer were investigated. The s‐IPN composition was varied with different monoacrylate/diacrylate monomer ratios and PVAc concentrations. The crosslinking density deeply affected the thermal behavior. The results showed that a more densely crosslinked acrylate network promoted phase mixing and a more homogeneous structure. The variation in the linear polymer concentration influenced both the morphology and mechanical properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Transformation of waterborne hybrid polymer particles into films: Morphology development and modeling

Films cast from multiphase polymer particles have the potential to combine the properties of their components synergistically. The properties of the film depend on the hybrid polymer architecture and the film morphology. However, how the polymer microstructure and particle morphology are transformed during film formation to determine the film morphology is not well understood. Here, using waterborne alkyd-acrylic nanocomposite particles in a case study, it was found that phase migration leading to the formation of aggregates occurred during film formation. A coarse-grained Monte Carlo model was developed to account for the effects of polymer microstructure and particle morphology on the morphology of the film. The model was validated by comparing its predictions with the observed effects, and then used to explore combinations of polymer microstructure and particle morphology not attainable with the system used as a case study. Significantly, the compatibility of the phases was found to have a greater influence than the morphology of the particles in determining the film structure.     

氨基甲酸酯基丙烯酸酯的合成及其光固化性能

利用碳酸亚乙酯与1,6-己二胺、异佛尔酮二胺反应，制备出两种含氨基甲酸酯基的二元醇，基于氨基甲酸酯二元醇与1,6-己二醇二丙烯酸酯（HDDA）、新戊二醇二丙烯酸酯（NPGDA）及三羟甲基丙烷三丙烯酸酯（TMPTA）本体条件下的Oxa-Michael加成反应及酯交换反应，合成出6种含氨基甲酸酯基的丙烯酸酯混合物。利用FTIR及高分辨质谱分析了产物结构，用FTIR考察了所合成氨基甲酸酯基丙烯酸酯光固化过程的动力学,测定了光固化膜的性能。结果表明，在含占总质量分数3% 的2-羟基-2-甲基-1-苯基-1-丙酮（1173）光引发剂的引发下，氨基甲酸酯基丙烯酸酯能在30s内固化形成表面平整、柔韧性（0.5~2.5mm）良好、透明或半透明的膜；固化膜的凝胶率及铅笔硬度分别为92%~96%、4~5H，对玻璃的附着力为0~1级。     

Determination of the influence of the polymer structure and particle size on the film formation process of polymers by atomic force microscopy

The particle size and morphology of a synthetic polymer latex were shown to influence the film formation behavior. Theoretical models predict that small particles coalesce more easily than large colloids do.The influence of particle size and morphology of differently structured lattices on the film-formation process was investigated by atomic force microscopy (AFM). Sequences of AFM images were acquired over a certain temperature range or at room temperature as a function of time. From the resulting images the average particle diameter of the latex particles in the surface layer was determined as a function of the time or temperature. The resulting curves could be compared to observe differences in the film formation kinetics of the different lattices. These AFM studies confirmed that the film formation behavior is influenced by the particle size and particle morphology, but that the core/shell ratio of core-shell particles has no significant influence on the film formation kinetics.     

Polymer diffusion and mechanical properties of films prepared from crosslinked latex particles

Wedescribe energy transfer (ET)measurements to follow polymer diffusion, as well as oscillatory dynamic mechanical measurements and tensile measurements, on films prepared from structured and unstructured latex particles consisting of a copolymer of butyl methacrylate and butyl acrylate with a T_g of 20°C. Structure was introduced in the form of a low level (1 mol%) of crosslinking, using seeded semi-continuous emulsion polymerization to control the locus of the crosslinking agent in the particles. Linear dynamic mechanical measurements showed the G′ and G″ were sensitive to the particle morphology, with particular sensitivity exhibited by the elastic modulus G′. The tensile properties were less sensitive to particle morphology; sufficient polymer diffusion occurs during film formation for the films to acquire strength and toughness. As expected, crosslinking increases strength but decreases elongation to break. Some interesting compromises could be found through control of the location of the crosslinked regions of the film. Dept. of Chemistry, 80 St. George St., Toronto, Ont., Canada M5S 3H6. F-27470 Serquigny, France.