Novel acrylic pressure-sensitive adhesive (PSA) containing silver particles

Acrylic pressure-sensitive adhesives (PSAs) are generally considered as nonelectrically conductive materials. The electrical conductivity is incorporated into acrylic polymer after blending with electrical conductive additives like silver particles. After the addition of electrically conductive silver filler, the main and typical properties of PSAs such as tack, peel adhesion, and shear strength will decline. This study is the first trial which reveals that the acrylic self-adhesive basis must be synthesized with ameliorated initial performances like high tack and excellent adhesion. Currently, the electrically conductive solvent-borne acrylic PSA containing silver fillers are not commercially available on the market. They are promising materials which can be applied for the manufacturing of diverse technical or medical high performance self-adhesive products, such as broadest line of special electrically conductive sensitive tapes.     

Silicone pressure-sensitive adhesives with selective adhesion characteristics

The peel, probe tack, and loop tack adhesion characteristics of peroxide-cured silicone pressure-sensitive adhesives (PSAs) are investigated with respect to adhesive composition, peroxide concentration, and type of substrate. These adhesion properties decrease with increasing benzoyl peroxide concentration and their adhesion values vary noticeably with the substrate type. However, the loop adhesion to 'difficult-to-wet' surfaces (e.g. silicone-coated substrates) can be selectively enhanced by incorporating an organofunctional silicone into the silicone PSA mixture. The enhancement in adhesion is attributed to a wetting/adhesion improvement at the adhesive- substrate interface, and relates to the type of organosilicone modifier in the order aminosilicone > vinylsilicone > epoxysilicone > fluorosilicone.     

Novel pyridinium derivatives as very efficient photoinitiators for UV-activated synthesis of acrylic pressure-sensitive adhesives

During the development of synthesis of acrylic pressure-sensitive adhesives, newly synthesized pyridinium derivatives were used by the UV-initiated polymerization quarantines of new polymer design for the synthesized self-adhesive acrylics with excellent performance, for which tack, peel adhesion, shear strength and shrinkage were measured. For example, the best tack and peel adhesion performances were achieved after 30 and 60 s UV radiation for 3.0 wt% pyridinium photoinitiator PPP, after 60 and 90 s UV exposure for 4.0 wt% pyridinium photoinitiator HPP and after 90 s UV-crosslinking in the case of 5.0 wt% pyridinium photoinitiator OPP. An increase of novel pyridinium photoinitiators concentration causes in an increase of the monomers conversion. For high photoinitiator content, characterized for each investigated photoinitiator, ranging from about 3.0 (PPP) to 5.0 wt% (OPP), the degree of monomer conversion reaches a maximum value of about 99.6 wt%.Preliminary results are reported illustrating the effectiveness of the acrylic PSA development.     

Rheological and adhesion properties of acrylic pressure‐sensitive adhesives

Different pressure‐sensitive adhesives (PSAs) based on acrylic monomers were synthesized under different reaction conditions. The synthesized PSAs have good adhesive properties and without leaving any residue can be easily peeled off from the surface of a substrate. The relationship between PSAs rheological behavior and its adhesion properties (e.g., peel, tack, and shear resistance) has been studied at constant adhesive thickness. The samples were examined for their surface energy and viscoelastic characteristics. It was observed that increase in reaction temperature and reaction time results in decreased storage modulus due to lowered molecular weight, which finally leads to lower elasticity of the PSA. While the storage (G′) and loss (G″) modulus of samples increase with increased initiator concentration, the elasticity of PSA is increased as well. High G″ at high frequency (100 Hz) represents high peel strength because of higher dissipation of viscoelastic energy during debonding. The tack values increase by lowering storage modulus at 1 Hz due to higher M_e. Shear values are increased by higher storage modulus at low frequency (0.1 Hz) due to hydrogen bonding of the different components. Some parallel investigations on the surface energy of the samples showed that they have different properties because of the nature of different monomeric units with their corresponding orientations. Our results reveal that the peel strength is not affected by surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

环保型低剥离力压敏胶的研制

采用半连续乳液聚合法制备了一种丙烯酸类水基型低剥离力压敏胶。主要考察了甲基丙烯酸(MAA)等功能单体和外加交联剂对产物性能的影响。实验表明,随MAA等亲水单体用量的增多,乳液粘度会增大,而引入交联单体在实验范围内可显著降低剥离强度。功能单体用量有一合适范围。选用较高反应活性的氨基树脂作交联剂,可改善耐温性,保持初粘力,得到综合性能较好的低剥离力压敏胶。     

Novel pyridinium photoinitiators and their applications for the ultraviolet crosslinking of acrylic pressure‐sensitive adhesives

The demand for ultraviolet (UV)‐crosslinkable pressure‐sensitive adhesives (PSAs) has rapidly been increasing. A variety of different PSAs containing new photoreactive pyridinium derivatives have been evaluated for their effectiveness in improving adhesion and cohesion in UV‐crosslinkable PSAs. PSAs have been evaluated with respect to the tack, peel adhesion, and shear strength. This article summarizes the breakthrough technology used to achieve better performances in UV‐crosslinkable acrylic PSAs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Miscibility and fracture energy of probe tack for acrylic pressure-sensitive adhesives: acrylic copolymer/tackifier resin systems

The relationship between the miscibility of acrylic pressure-sensitive adhesive (PSA) and the fracture energy (W) (Jm⁻²) of the probe tack was investigated, wherein the master curve of W was compared with that of the maximum force (σ_max) (gf) of the probe tack. It was ascertained that W of acrylic PSA was closely related to the miscibility between the components (acrylic copolymer and tackifier resin). In the case of the miscible blend system, the master curve of W shifted toward the lower rate side and, at the same time, the magnitude decreased as the tackifier resin content increased. The degree of the shift of W was extremely smaller than that of σ_max. In the case of the immiscible blend system, the master curve of W remarkably decreased as the tackifier resin content increased, which suggests the fact that W of the PSA depended on the dynamic mechanical properties of the matrix phase and that the resin-rich phase acted as a kind of filler, thus reducing the practical performance. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 581–587, 1998     

The thermal degradation of acrylic pressure-sensitive adhesives based on butyl acrylate and acrylic acid

The thermal degradation of acrylic pressure-sensitive adhesives at 250 °C was investigated using pyrolysis-gas chromatography. Knowledge of the types and amounts of pyrolysis products will provide important information on the thermal degradation of acrylic adhesives and the mechanisms involved. Unsaturated monomers including butyl acrylate and butyl methacrylate were formed during thermal degradation of butyl acrylate–acrylic acid copolymers. As a result of side chain reactions in the thermal destruction of the butyl acrylate–acrylic acid-based self-adhesives, a remarkable amount of butyl alcohol was produced. The unsaturated monomers formed as a result of thermal degradation could potentially be used in a new polymerization process.     

Influence of crosslinking and peeling rate on tack properties of polyacrylic pressure-sensitive adhesives

Tack properties and peeling behavior of crosslinked polyacrylic pressure-sensitive adhesives were investigated. The model adhesive was a crosslinked poly(n-butyl acrylate-acrylic acid) random copolymer with an acrylic acid content of 5?mol% with various crosslinking degrees. Tack was measured using a probe tack test with probe rates of 1 and 10?mm/s and various contact time. The tack increased with contact time. The degree of tack rising with contact time decreased with an increase in crosslinking degree for 10?mm/s, while the tendency was opposite for 1?mm/s. The temperature dependency of tack was measured with a contact time of 30?s. The tack peak shifted to higher temperatures with an increase in crosslinking degree and probe rate. Peeling behavior was observed using high-speed microscopy. The peeling behavior changed from A to C with the decrease of peeling rate and crosslinking degree. A: Cavitation and peeling progressed simultaneously at maximum stress at 10?mm/s independent on the crosslinking degree. B: Cavitation occurred at the edge of the probe at low stress and spread to the center of the probe at maximum stress at 1?mm/s and high crosslinking degree, then peeled out. C: After B, fibrillation occurred at 1?mm/s with low crosslinking degree. The change of peeling behavior was caused by the following: the interfacial adhesion increased, while the cohesive strength decreased as crosslinking degree and probe rate decreased.     

交联型聚丙烯酸酯压敏胶乳液的合成及其粘接性能的研究

利用功能单体的自交联作用,采用种子半连续乳液聚合的方法进行多元共聚,合成了兼具较高剪切强度和剥离强度的交联型聚丙烯酸酯压敏胶乳液。运用DSC、DMA及粘接性能测试分别考察了聚合物的玻璃化转变温度、动态力学性能和压敏胶粘性能,并分析讨论了三者之间的相互关系。结果表明:功能单体所产生适度交联作用能较好地协调聚合物的内聚力和粘合力之间的平衡,使其具有较好的粘接及力学性能。聚合物的Tg、粘弹性等物理参数可用于评估其内聚力及粘接强度。     

Influence of selected photoinitiators on important properties of photoreactive acrylic pressure‐sensitive adhesives

Photoreactive solvent‐borne pressure‐sensitive adhesives are not commercially available in the market. The reason for it is that the UV‐initiated crosslinking has sense only in the case of solvent‐free self‐adhesive systems. Investigations conducted in Institute of Chemical Organic Technology have shown that the photoreactive solvent‐borne acrylic PSA are conventional crosslinked solvent‐borne acrylic PSA used as crosslinking agents typical metal chelates as titanium acetylacetonate (TiACA), aluminum acetylacetonate (AlACA) or thermal reactive crosslinker melamine‐formaldehyde resin Cymel 303 clear considered. The main purpose of the investigation was to study the influence of diverse photoinitiators on main properties, such as shrinkage, tack, peel adhesion, and shear strength of solvent‐based acrylic pressure‐sensitive adhesives. The interesting alternative to conventional photoinitiators is unsaturated photoinitiators described in this article. Following unsaturated photoinitiators were used: 4‐acryloyloxy benzophenone, 4‐acryloyloxyethoxy benzophenone, and 4‐acryloyloxybutoxy benzophenone. The influence of the crosslinking agents or crosslinking methods was determined in relation to the reaction time and to the concentration versus adhesion properties. The increase of photoinitiator concentration causes in the decrease of the shrinkage. Increasing the UV dose during the crosslinking of acrylic PSA film leads clearly to better shrinkage resistance. The best results of the lowest shrinkage value of 0.35% were given by using 4‐acryloyloxy benzophenone. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Sustainable UV-Crosslinkable Acrylic Pressure-Sensitive Adhesives for Medical Application

This study aimed to investigate the potential of photoreactive acrylate patches as systems for transdermal drug delivery, in particular, using more renewable alternatives and more environmentally friendly synthesis routes of transdermal patches. Therefore, the aim of this study was to develop a transdermal patch containing ibuprofen and investigate its performance in vitro through the pigskin. Transparent patches were prepared using four acrylate copolymers with an incorporated photoinitiator. Two types of transdermal patches based on the photocrosslinking acrylic prepolymers with isobornyl methacrylate as biocomponent and monomer increasing Tg (“hard”) were manufactured. The obtained patches were characterized for their adhesive properties and tested for permeability of the active substance. It turns out that patches whose adhesive matrix is photoreactive polyacrylate copolymers have a higher cohesion than patches from commercial adhesives, while the modification of the copolymers with isobornyl methacrylate resulted in an improvement in adhesion and tack. This study demonstrates the feasibility of developing photoreactive acrylic-based transdermal patches that contain biocomponents that can deliver a therapeutically relevant dose of ibuprofen.     

Evaluation of the Structural Modification of Ibuprofen on the Penetration Release of Ibuprofen from a Drug-in-Adhesive Matrix Type Transdermal Patch

This study aimed to evaluate the effect of chemical modifications of the structure of active compounds on the skin permeation and accumulation of ibuprofen [IBU] from the acrylic pressure-sensitive adhesive used as a drug-in-adhesives matrix type transdermal patch. The active substances tested were ibuprofen salts obtained by pairing the ibuprofen anion with organic cations, such as amino acid isopropyl esters. The structural modification of ibuprofen tested were Ibuprofen sodium salt, [GlyOiPr][IBU], [AlaOiPr][IBU], [ValOiPr][IBU], [SerOiPr][IBU], [ThrOiPr][IBU], [(AspOiPr)₂][IBU], [LysOiPr][IBU], [LysOiPr][IBU]₂, [PheOiPr][IBU], and [ProOiPr][IBU]. For comparison, the penetration of unmodified ibuprofen and commercially available patches was also investigated. Thus, twelve transdermal patches with new drug modifications have been developed whose adhesive carrier is an acrylate copolymer. The obtained patches were characterized for their adhesive properties and tested for permeability of the active substance. Our results show that the obtained ibuprofen patches demonstrate similar permeability to commercial patches compared to those with structural modifications of ibuprofen. However, these modified patches show an increased drug permeability of 2.3 to even 6.4 times greater than unmodified ibuprofen. Increasing the permeability of the active substance and properties such as adhesion, cohesion, and tack make the obtained patches an excellent alternative to commercial patches containing ibuprofen.     

Effect of monomer concentration on the adhesive properties of acrylic pressure-sensitive adhesives

2-Ethylhexyl acrylate (2-EHA)-based co- and terpolymers were synthesized using n-butyl methacrylate (nBMA) and acrylic acid (AA) as comonomers. The change in adhesive properties with the change in monomer concentration was studied. The adhesive, cohesive, and tack characteristics were evaluated under standard conditions as specified by ASTM and/or the Pressure-Sensitive Tape Council (PSTC). The 2-EHA-co-nBMA copolymers showed a good balance between these three characteristics at 50% concentration of 2-EHA. It is noteworthy that with the AA concentration at or above 30% in 2-EHA-co-AA, the polyacrylates lose the tack which is necessary for adhesive bond formation. The 2-EHA-co-AA-co-nBMA terpolymers, where the 2-EHA content was kept constant at 50% and the AA content was varied from 1% to 10% with a corresponding variation in nBMA from 49% to 40%, showed an excellent balance between adhesive, cohesive, and tack strength.     

耐热丙烯酸酯压敏胶粘剂(带)的研制

介绍了耐热高强度丙烯酸酯压敏胶粘剂 (带 )的研制方法 ,讨论了各种单体配比、引发剂、交联剂、溶剂、聚合温度、时间和工艺等因素对压敏胶粘剂性能的影响     

Preparation and characterization of modified telechelic natural rubber-based pressure-sensitive adhesive

Telechelic natural rubber (TNR) was prepared by the use of potassium persulfate and propanal at 70 °C and various degradation times from 0 to 30 h. These samples were then grafted by maleic anhydride (MA) in toluene solution before modification with 3-amino-1,2,4-triazole (ATA) to produce modified TNRs (AMTNRs). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to identify the chemical compositions. Carboxyl and hydroxyl groups of TNRs were clearly observed, due to chain scission, oxidation, and modified chain ends. The viscosities of TNRs were dropped greatly after 5 h and then decreased slowly as a function of degradation time. ATR-FTIR spectra of AMTNRs showed amide bonds between ATA and MA groups, and then the multiple hydrogen bonding arrays were formed. The glass transition temperatures (T_g) of AMTNRs were determined by differential scanning calorimetry. The T_g of AMTNR_0 moved to a higher temperature of –55 °C after modification by ATA, confirming the formation of multiple hydrogen bonding arrays. However, the T_g of AMTNR_5 to AMTNR_30 decreased slightly due to chain scission in the degradation process. The adhesive properties of AMTNR-based pressure-sensitive adhesive were evaluated by a Lloyd adhesion tester. The tack of AMTNRs depended on wettability whereas peel and shear strengths were responded by a combination between wettability and multiple hydrogen bonding arrays.     

Rheology and adhesive properties of filled PIB-based pressure-sensitive adhesives. I. Rheology and shear resistance

Two nanosized fillers (fumed silica Rosil-175 up to 20 wt% and halloysite nanotubes up to 40 wt%) were used to suppress cold flow of polyisobutylene (PIB)-based adhesives. Rheological measurements revealed the presence of the yield stress in the PIB-halloysite system which is indicative of the three-dimensional network formation in the bulk of the matrix. However, further rheology tests identified low strength of the network. In case of Rosil, no yield stress was detected, only gradual increase in the viscosity. Shear bank testing showed 4–5 times increase in the PIB-halloysite system time to failure when 40 wt% of halloysite was incorporated into the PIB matrix. Increase in the time to failure for PIB-Rosil systems was over two orders of magnitude – at the Rosil content up to 20 wt%. Such superior properties of the Rosil adhesion joints are considered to be the result of Rosil high specific area and low strength of the halloysite nanotubes network.     

亲水性聚氨酯压敏胶经皮给药应用性能研究

针对目前经皮给药制剂发展急需性能优良的亲水性新型压敏胶基质,制备了亲水性聚氨酯压敏胶。对一些影响压敏胶贴剂力学性能的因素进行了考察,并重点研究了载药压敏胶贴剂经皮释放规律。结果表明,该聚氨酯压敏胶贴剂具有良好的药物控释能力,适用于经皮给药系统。     

不同基团对丙烯酸酯胶粘剂胶粘性能影响的研究

介绍了通过共聚分别把－ＣＮ、－ＣＯＯＨ、－ＣＯＮＨ_２、－Ｃ_６Ｈ_５、－ＯＨ等基团引入丙烯酸酯大分 子链中,研究了这些基团分别对丙烯酸酯胶粘剂剥离强度和内聚强度的影响。试验结果表明：这些极性基团 的引入都使胶粘剂的剥离强度和内聚强度有不同程度的提高,其中－ＣＯＮＨ_２使之提高的幅度较大,－ＣＯＯＨ、 －ＯＨ次之,－Ｃ_６Ｈ_５、－ＣＮ使之提高的幅度较小。     

Application of selected 2-methylbenzothiazoles AS cationic photoreactive crosslinkers for pressure-sensitive adhesives based on acrylics

Since their introduction half a century ago, acrylic pressure-sensitive adhesives have been successfully applied in many fields. They are used in self-adhesive tapes, label signs, marking films and protective films as well as in medical pharmaceutical applications for plaster, in dermal dosage systems and in a wide range of biomedical electrodes. In the last 15 years or so, the UV technology, especially UV-crosslinking, is well established in the market and allows the production of UV-crosslinkable pressure-sensitive adhesives (PSA) based on acrylics with interesting performance. So much so that the larger manufacturers of pressure-sensitive adhesive materials and their suppliers now use very expensive equipment to study pressure-sensitive adhesive behavior: tack, peel adhesion and shear strength. The balance between adhesive and cohesive strength after the crosslinking process is very important and critical for properties of acrylic PSA in form of self-adhesive films. In this work the cationic UV-crosslinking of acrylic PSA containing epoxy groups in their structure and additionally cationic photoinitiators based on 2-methylbenzothiazoles as photoreactive crosslinkers have been investigated using UV-lamp as ultraviolet sources. The investigated acrylic PSA were synthesized from 80 wt% of butyl acrylate, and 20 wt% of glycidyl methacrylate. The use of selected photoreactive crosslinkers: 1,5-bis[N,N׳-(2-methylbenzothiazolium)]pentane diiodide and 1,10-bis[N,N׳-(2-methylbenzothiazolium)]decane diiodide allows manufacturing of high quality PSA materials with interesting properties, such as high tack, high peel adhesion, and excellent shear strength.