Eco-friendly UV-curable pressure sensitive adhesives containing acryloyl derivatives of monosaccharides and their adhesive performances

Two different monosaccharide acrylate monomers were designed and synthesized from glucose and galactose, and were then used to prepare transparent acrylic pressure sensitive adhesives (PSAs) comprised of semi-interpenetrated structured polymer networks. The effects of the monosaccharide architecture in the acrylate monomers on the adhesive performance of the acrylic PSAs were investigated. Prepared UV-curable acrylic PSA syrups were characterized and the optical properties of the acrylic PSAs were also examined. All of the acrylic PSAs exhibited high transparency in the visible wavelength region. With increasing monosaccharide acrylate concentration in the acrylic PSAs, adhesive performances such as the peel strength, cohesion strength, and probe tack were increased. However, there was no difference in their adhesive performances regardless of the different chemical structures of monosaccharide acrylate monomers.     

Nano- and bulk-tack adhesive properties of stimuli-responsive, fullerene-polymer blends, containing polystyrene-block-polybutadiene-block-polystyrene and polystyrene-block-polyisoprene-block-polystyrene rubber-based adhesives

Nano-tack (measured using AFM) and bulk-tack adhesive forces of blends of C₆₀ and either polystyrene-block-polybutadiene-block-polystyrene (SBS) or polystyrene-block-polyisoprene-block-polystyrene (SIS) triblock copolymer pressure sensitive adhesives were measured after exposure to white light irradiation. The nano-tack adhesive forces in C₆₀-SIS/SBS were found to decrease with increasing C₆₀ concentration and exposure time, approaching the value for 100% polystyrene, providing an indication that significant surface hardening and crosslinking of the soft isoprene and butadiene phases occurs in the presence of C₆₀. Films produced during the study were smooth, having low RMS surface roughness, and showed nanoscale phase separation between the soft (diene) and hard (styrene) segments. This phase separation disappeared after addition of C₆₀ sensitizer and white light irradiation. Bulk adhesive measurements (tack and peel strength) showed a similar trend with C₆₀ concentration and exposure time, and in irradiated systems containing as little as 0.2 wt% C₆₀, a significant decrease in adhesion was observed. Estimated T_g (measured using DMA, shear mode) of the soft-block shifts to higher temperatures (increasing by 30-40 °C), and high gel fractions were obtained, indicating the presence of chemically crosslinked networks.     

Miscibility enhancement of supramolecular polymer blends through complementary multiple hydrogen bonding interactions

We have investigated the miscibility behavior and specific interactions of supramolecular poly[vinylbenzylthymine‐co‐(butyl methacrylate)] (T‐PBMA) and poly[(2‐vinyl‐4,6‐diamino‐1,3,5‐triazine)‐co‐styrene] (VDAT‐PS) blends with respect to their vinylbenzylthymine (VBT) and 2‐vinyl‐4,6‐diamino‐1,3,5‐triazine (VDAT) contents. Fourier transform infrared spectroscopy revealed that multiple hydrogen bonding interactions occurred exclusively between the VDAT and VBT units, which were stronger than adenine and thymine interactions. A miscibility window occurred in the VDAT‐PS/T‐PBMA blend system when the VBT and VDAT fractions in the copolymers were greater than 7 mol%, as predicted using the Painter–Coleman association model. Copyright © 2010 Society of Chemical Industry     

压敏胶与压敏制品的市场和技术动向(Ⅱ)

综述美国、西欧、日本、中国及台湾地区等国家或地区的压敏胶与制品的最近市场需求 ,和各类压敏胶与制品的开发和生产技术动向     

Crosslinked acrylic pressure sensitive adhesives. 3. Effect of adherend on film formation

The reaction of isocyanate in pressure sensitive adhesive (PSA) films adhered on to various adherends having different surface tensions was monitored by depth profiling using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy.In the latter stages of crosslinking reaction, unreacted isocyanate and its derivatives exist more in the bulk of the PSA than in the interfaces between PSA and adherends which are Teflon sheet and PE film having relatively lower surface tensions. In the case of using stainless steel having relatively higher surface tension as adherend, opposite segregation was observed compared to Teflon and PE.From X-ray photoelectron spectroscopy (XPS), it was revealed that N atoms exist more in surface than in bulk when stainless steel is used as adherend. We conclude that polyisocyanates migrate in the PSA film in order to minimize the magnitude of interfacial free energy between the PSA and the adherend, which leads to the change of surface tension of PSA film.     

Relationship between the fracture energy and the mechanical behaviour of pressure-sensitive adhesives

Mechanical behaviours of two pressure-sensitive adhesives (PSAs) families, composed of elastomer copolymers or polyacrylate/acrylic copolymers, are characterised by peel tests. Fracture energy varies linearly according to the applied contact force between two levels, which depends on tackiness and cohesion of the PSA. Local fracture energies are measured by an original peeling system and they are related with the adhesive deformation. Mechanical behaviours of PSAs depend on their composition but majority of fracture energy is dissipated on the first millimetre near the bending zone where fibrils elongation is maximum. Observations of interfaces between PSAs and glass substrate underline that fracture energy varies linearly according to the contact area.     

High performance pressure sensitive adhesives by miniemulsion photopolymerization in a continuous tubular reactor

High solids content PU/(meth)acrylics latexes for application as pressure sensitive adhesives (PSAs) were successfully synthesized by miniemulsion photopolymerization in a continuous tubular reactor at room temperature. It was shown that the process is very flexible and the polymer microstructure can be widely changed by simply controlling the radical initiation using different photoinitiator types and concentrations and varying the incident light irradiance. PSAs presenting a whole spectrum adhesive properties were obtained, some of them having the desired and unusual combination of high work of adhesion and maximum shear adhesion failure temperature (SAFT > 210 °C). The adhesive properties were analyzed in terms of the molecular weight distribution of the whole sample measured by asymmetric flow field flow fractionation.     

Multifunctional propyleneimines-new generation of crosslinkers for solvent-based pressure-sensitive adhesives

This article describes work with the goal of crosslinking pressure sensitive acrylic adhesives (PSA) and a new generation of crosslinkers based on multifunctional propyleneimine derivates. Crosslinking of PSA is an established technology used in many industrial manufacturing processes. New applications and technical specifications stimulate the continuous development of new crosslinking agents with very interesting properties. These new crosslinkers influence physico-mechanical properties of acrylic PSA such as tack, peel resistance (adhesion) and shear strength (cohesion). The weak point of propyleneimine crosslinkers is their very short potlife.     

The application research of environment-friendly reactive surfactants in acrylate emulsion pressure sensitive adhesives

In this article acrylate pressure sensitive adhesive (PSA) latexes were synthesized via a pre-emulsion seeded semi-batch emulsion polymerization process with a conventional nonreactive surfactant (CO-436) and two polymerizable surfactants (traditional surfmer SE-10N and environment-friendly surfmer SR-10). The effects of surfactant contents on the particle size, zeta potential, electrolyte stability of the latexes and gel content, sol molecular weight (M_w, M_n), water absorption of the PSA copolymers were investigated. In addition, X-ray photoelectron spectroscopy (XPS) and contact angle measurements were used to characterize the latex films. The results showed that the particle sizes of latexes prepared with surfmers were smaller than their CO-436 containing counterparts. And the latexes prepared with surfmers had a lower storage stability than the one prepared with CO-436. However, surfmers can improve the electrolyte stability of the latex. Furthermore, the water resistances of the latexes prepared with surfmers were better than that of the latex with CO-436, which can be confirmed by water absorption, contact angle and XPS analysis. The results also indicated that the PSA prepared with SR-10 exhibited the highest gel content among the three surfactants. Finally, the effects of surfactants on the adhesive properties of the PSAs were also evaluated.     

Improving the properties of water-borne pressure sensitive adhesives by using non-migratory surfactants

The adhesive performance of high solids content water-borne acrylic pressure sensitive adhesives synthesized using polymerizable surfactants (Latemul^®PD-104 and Sipomer^®Pam-200) or a polymerizable stabilizer (Sipomer^®Cops-1) has been studied. The use of a high pH during the polymerization process has a deleterious effect on the final adhesive properties because gel polymer is not formed. Interestingly, at low pH it is found that the surfactant concentration used during the polymerization process has also an effect on the polymer microstructure; the higher the surfactant concentration, the higher the final gel content of the latex. When polymerizable surfactants or a stabilizer are used the peel strength of the final films is considerably improved due to the surfactant incorporation into the polymer backbone and hence reduced surfactant migration to the air-film interface. Work of adhesion and shear adhesion failure temperature (SAFT) are not noticeably affected by surfactant migration but their performance is affected by the surfactant employed.     

Melt Synthesis and Characterization of Aliphatic Low-Tg Polyesters as Pressure Sensitive Adhesives

Polyesters, which are readily synthesized in the absence of solvent, are excellent candidates for a new generation of pressure sensitive adhesives (PSAs) due to their low cost and potential biodegradability. In this study, linear, all-aliphatic polyesters with low glass transition temperatures (T_g) were synthesized using a solvent-free, environmentally friendly melt polycondensation methodology. Polyesters of various compositions were synthesized from different diol and diester monomers to adjust the glass transition temperature and achieve optimum adhesive properties. Melt polycondensation of an isomeric mixture of dimethyl-1,4-cyclohexane dicarboxylate (DMCD), dimethyl adipate (DMAP), diethylene glycol (DEG), and triethylene glycol (TEG) generated a series of linear low-T_g polyesters. The synthesized polyesters were characterized using size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and ¹H NMR spectroscopy. The frequency- and temperature-dependent properties of the low-T_g polyesters were characterized using dynamic mechanical analysis (DMA). The adhesive performance of the polymers was evaluated using tack, peel, and shear strength measurements at ambient humidity and temperature. The low-T_g polyesters exhibited peel and tack properties comparable with commercial acrylic adhesives.     

我国胶粘剂工业发展趋势与对策

介绍了世界合成胶粘剂的现状与趋向 ,评述中国胶粘剂工业现状与趋势 ,并提出具体的发展对策     

丙烯酸酯乳液胶粘剂的研究及应用

综述了近年来我国丙烯酸酯乳液胶粘剂的最新研究现状,并介绍了丙烯酸酯乳液胶粘剂在压敏胶及包装材料中的应用,指出了我国丙烯酸酯乳液胶粘剂的发展方向。     

Preparation of waterborne polyurethane adhesives based on macromolecular-diols containing different diisocyanate

ABSTRACT

Three different macromolecular diols were synthesized by the reaction of Poly(1,4-butanediol adipate) diol (PBA) and diisocyanate (Isophorone diisocyanate (IPDI), Hexamethylene diisocyanate (HDI) and Methylene-bis(4-cyclohexylisocyanate)(HMDI)) at the ratio of 2:1. Based on these macromolecular diols, waterborne polyurethane (WPU) adhesives were prepared. The structure and molecular weights of the WPU were characterized by Nuclear magnetic resonance spectroscopy (¹H NMR), Fourier Transform Infrared Spectroscopy (FTIR) and Gel permeation chromatography (GPC) respectively. Furthermore, the hydrogen bonding interaction of WPU were analyzed by the deconvolution FTIR spectra. The results showed that the hydrogen bonded NH was increased when carbamate was in the soft segment. The crystallinity of WPU was tested by X-ray diffraction (XRD) and Differential scanning calorimetry (DSC). The results showed that the crystallinity of WPU2 (HDI) and WPU3 (HMDI) were enhanced, especially for WPU2. Meanwhile, the Tg,s as well as the mechanical strength, storage modulus, the contact angle and thermo-stability were increased with the introduced carbamate into soft segment. The T-peel tests of plasticized PVC/WPU/plasticized PVC joints and lap-shear tests of wood/WPU adhesive/wood joints were carried out. The results indicated that the carbamate in the soft segment could significantly enhance the adhesion of WPU at an appropriate activation temperature.     

丙烯酸酯类压敏胶的合成与性能研究

以丙烯酸丁酯（BA）、丙烯酸异辛酯（2-EHA）、醋酸乙烯酯（VAc）、丙烯酸（AA）、丙烯酸羟丙酯（HPA）为原料,乙酸乙酯为溶剂,过氧化苯甲酰为引发剂制备了五元共聚丙烯酸酯类压敏胶。考查了软单体组成、软硬单体配比、丙烯酸用量、丙烯酸羟丙酯加量、增粘树脂对压敏胶性能的影响。实验结果表明,当软单体m2-EHA：mBA=2：1、软硬单体的质量比为6：1、丙烯酸用量为5％、丙烯酸羟丙酯加量为8％、松香用量为5g时,压敏胶性能较佳。     

Cellulose nanocrystals (CNCs) reinforced acrylic pressure- sensitive adhesives (PSAs) prepared via miniemulsion polymerization

In this study, poly (n-butyl acrylate-co-2-ethyl hexyl acrylate) (P(nBA-co-2EHA)) pressure sensitive adhesives (PSAs) were successfully synthesized in the presence of cellulose nanocrystals (CNCs) via in-situ miniemulsion polymerization. First, the CNCs were prepared via acid hydrolysis of cellulose microcrystals (CMCs) at various temperatures, 42–54 °C, and characterized using atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) apparatus. The results showed that hydrolysis of MCCs at 45 °C resulted in CNCs with a well-defined aspect ratio, average length of 206 nm and thickness of 3.9 nm, and the highest crystallinity. Adding further CNC to the copolymer adhesive enhanced the mean particle size of the composite latex and decreased the glass-rubber transition temperature (T_g) of the copolymer matrix. Molecular weights and viscoelastic properties of the resultant PSAs were determined using gel permeation chromatography (GPC) and dynamic mechanical thermal analysis (DMTA), respectively. Adhesion performance of the neat and reinforced PSAs containing 1–5 wt% CNCs was evaluated at room temperature. The results showed that the incorporation of CNCs up to 4 wt% in the copolymer adhesive increased the shear resistance by 518%, peel strength by 176% and probe tack by 13%, while further addition, 5 wt%, lowered the adhesion performance due to a lack of surface wettability.     

Thermoplastic polyurethane pressure sensitive adhesives made with mixtures of polypropylene glycols of different molecular weights

New more simple and easier strategy for synthesizing thermoplastic polyurethane pressure sensitive adhesives (TPU PSAs) has been proposed. Thus, the properties of the TPU PSAs were adjusted by fixing the NCO/OH ratio to 1.1 and varying the content of the hard segments by mixing high molecular weight and low molecular weight polyether polyols during TPU synthesis. The thermoplastic polyurethanes have been synthesized with methylene diisocyanate (MDI), 1,4 butanediol chain extender and different mixtures of two polypropylene glycols (PPGs) polyols with different molecular weights (450 and 2000 Da). TPUs with different hard segments content (12.5–38.7%) were synthesized and their pressure sensitive adhesive properties depended on their hard segments contents and degree of phase separation. In general, the TPU PSAs with higher hard segments content exhibited low probe tack and low loop tack regardless of the nature of the metallic and polymeric substrate. In contrast, the 180° peel strength depended noticeably on the nature of the polymeric substrate and on the hard segments content of the TPU. TPU PSAs with hard segments content lower than 20.9% were general purpose or removable PSAs and the ones with higher hard segments content were high shear PSAs.     

UV curable pressure‐sensitive adhesives for fabricating semiconductors. I. Development of easily peelable dicing tapes

In order to develop easily peelable dicing tapes from diced wafers, UV curing of various pressure‐sensitive adhesives (PSAs) was studied. After UV irradiation, the adhesive strength of a PSA composition including a diacrylourethane oligomer (UDA) decreased drastically compared with other compositions. Because of network formation via UV irradiation, this composition had a greater volume contraction that might yield microvoids at the interface between the adhesive and the wafer, resulting in the loose adhesion. Its storage modulus increased up to about 1000 times that before UV curing, which was due to the crosslinking of the UDA component. It was suggested that the increased crosslinking density and the high internal coagulant energy of the UDA backbone structure caused a remarkable decrease of the adhesive strength. Furthermore, it was ascertained that the UV‐irradiated UDA adhesives left few residual deposits on the wafer released from the tape. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 436–441, 2003     

Effect of propyleneimine external cross-linker on the properties of acrylate latex pressure sensitive adhesives

Acrylate pressure sensitive adhesive (PSA) latexes were synthesized via a starved monomer seeded semi-batch emulsion polymerization process with butyl acrylate (BA), methyl methacrylate (MMA), acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA). These PSA polymers were then cross-linked with trifunctional propyleneimine external cross-linker (SAC-100) to study the cross-linking reaction between carboxylic group of the polymer chain and cross-linking agent. It was found that cross-linking provided a significant influence on the film formation process based on the result of SEM analysis. In addition, with the increase of SAC-100 content, the gel content of the polymer increased significantly, while molecular weight between cross-link points (M_c) and the sol molecular weight (M_w, M_n) of the polymer decreased remarkably. The TGA result showed that the addition of the external cross-linker can enhance the thermal stability of the latex film. Moreover, for the cross-linked adhesive film, the shear strength was improved greatly while at the sacrifice of loop tack and peel strength, when compared with the uncross-linked counterparts. Besides, dynamic mechanical analysis (DMA) was also used to evaluate the viscoelastic properties of the acrylate emulsion PSA film.     

Various ways to control the bulk properties of pressure sensitive adhesives

The widespread industrial use of pressure sensitive adhesives (PSAs) is based on the advantage that PSAs can maintain sufficient bond strength, as well as, if needed, they can also be cleanly removed. These two essential requirements must be balanced to be a good PSA, and are not obtained without an accurate control of rheological properties. In this study, a new type of creep test is devised to measure the rheological behavior of thin film PSAs with high precision. Based on this technique, we studied four different methods to control the viscoelastic properties of PSAs. These are (1) control of the amount of crosslinking agent, (2) use of plasticizers, (3) adjustment of PSA film thickness, and, (4) construction of PSA double-layers. It was found that the levels of creep could be controlled over a wide range by adjusting the amount of crosslinking agent. Samples containing plasticizers behaved similarly to the PSAs with less amount of crosslinker (thus more mobile). The increase of film thickness also led to an increase of creep in a similar fashion as noted above. The creep behavior of the double-layer PSAs, composed of two PSA layers with different levels of crosslinking and thickness, followed a reasonable prediction: the total deformation, δ_t, was always less than the amount predicted by the two-phase model in which the limits are determined by two single layers of soft and hard PSA; however, δ_t was greater than the level of creep based on the one-phase model in which a complete mixing of crosslinker within the two PSA layers is assumed. In the last part, some characteristic creep behaviors of selected PSAs are discussed based on a linear viscoelastic model.