Hot-melt Pressure-sensitive Adhesives Research Articles

Amphiphilic hot-melt pressure sensitive adhesives for transdermal administration made from low melt-processing temperature OSISO copolymers

Herein, an anionic polymerization method was employed to synthesize a series of amphiphilic poly(ethylene oxide-b-styrene-b-isoprene-b-styrene-b-ethylene oxide) penta-block copolymers (OSISO). Their molecular structure and properties were comprehensively characterized using GPC,1H-NMR, thermodynamic rheological testing and water contact angle test. Notably, the hydrophilic characteristics exhibited a proportional increase with the rise in poly(ethylene oxide) (PEO) content, ranging from 1.3 to 12.6 wt%. The polystyrene blocks with low number-average molecular weight (2000–3500) reduced the copolymer melt viscosity, surpassing a tenfold decrease than the control sample within the temperature range of 50–150 °C. Resultantly, this series of OSISO copolymers could be used to develop amphiphilic hot-melt pressure-sensitive adhesives (HMPSAs) by low temperature hot-melt processing method (<120 °C). HMPSAs loaded with 2 wt% of geniposide, prepared by an optimized composition formula of OSISO copolymers, tackifiers, and plasticizers (in a ratio of 5:5:2), displayed excellent in vitro drug release performance. Additionally, these adhesives presented impressive 180° peeling strength (0.05–0.14 kN/m) without residues left on the substrate in the 180° peeling tests. The incorporation of PEO block significantly enhanced both the adhesive properties and accumulative drug release. Geniposide showed a burst release behavior with a moderate accumulative drug release (15–30 wt%), attributed to the PEO phase without crystallization behavior of long PEO chains.

Enhancing effect of phosphoric acid on release of loxoprofen sodium in hot-melt pressure-sensitive adhesives based on polystyrene-isoprene-styrene

Enhancing effect of phosphoric acid on release of loxoprofen sodium in hot-melt pressure-sensitive adhesives based on polystyrene-isoprene-styrene

Bottlebrush Thermoplastic Elastomers as Hot-Melt Pressure-Sensitive Adhesives.

Hot-melt pressure-sensitive adhesives (HMPSAs) are used in applications from office supplies to biomedical adhesives. The major component in HMPSA formulations is thermoplastic elastomers, such as styrene-based block copolymers, that provide both mechanical integrity and moldability. Since neat polymer networks are unable to establish an adhesive bond, large quantities of plasticizers and tackifiers are added. These additives enhance the adhesive performance but complicate the phase behavior and property stability of the pressure-sensitive adhesive. Herein, we introduce an alternative additive-free approach to HMPSA design based on self-assembly of bottlebrush graft-copolymers, where side chains behave as softness, strength, and viscoelasticity mediators. These systems maintain moldability of conventional thermoplastic elastomers, while architecturally disentangled bottlebrush network strands empower several benefits such as extreme softness for substrate wetting, low melt viscosity for molding and 3D-printing, and a broad frequency range of viscoelastic responses for adhesion regulation within almost four orders of magnitude. The brush graft-copolymers implement five independently controlled architectural parameters to regulate the Rouse time, work of adhesion, and debonding mechanisms.

Hot-Melt and Pressure-Sensitive Adhesives Based on Styrene-Isoprene-Styrene Triblock Copolymer, Asphaltene/Resin Blend and Naphthenic Oil.

Asphaltene/resin blend (ARB) extracted from heavy crude oil was used to modify poly(styrene-block-isoprene-block-styrene) (SIS) to make it an adhesive. There were prepared double and triple mixtures containing 10–60% SIS, 10–40% ARB, and 10–50% naphthenic oil used as an additional plasticizer. The viscoelasticity of the mixtures at 25 °C and 120 °C was studied, their flow curves were obtained, and the temperature dependences of the loss tangent and the components of the complex modulus were measured. In addition, the mixtures were used as hot-melt adhesives (HMAs) and pressure-sensitive adhesives (PSAs) in the shear, peel, and pull-off tests of the adhesive bonds that they formed with steel. Both naphthenic oil and ARB act as plasticizers for SIS and make it sticky. However, only the combined use of ARB and the oil allows for achieving the best set of adhesive properties of the SIS-based mixture. High-quality HMA requires low oil content (optimal SIS/ARB/oil ratio is 50/40/10, pull-off adhesion strength (τt) of 1990 kPa), whereas a lot of the oil is needed to give SIS characteristics of a PSA (SIS/ARB/oil is 20/40/40, τt of 100 kPa). At the same time, the resulting PSA can be used as a hot-melt pressure-sensitive adhesive (HMPSA) that has many times lower viscosity than HMA (13.9 Pa·s versus 2640 Pa·s at 120 °C and 1 s−1) but provides a less strong adhesive bond (τt of 960 kPa).

Single-lap joint creep behaviour of two soft adhesives

ABSTRACT Two hot melt pressure sensitive adhesives have been submitted to bonded joint creep tests. An amorphous and a semicrystalline adhesives have been considered for their different microstructures leading to different mechanical behaviors. The adhesives are referred as soft since their glass transition temperatures stand well below the temperatures of applications, resulting in low stiffnesses. The creep of structural joints has been characterized with single-lap joint tests. Two types of adherends were considered either glass or stainless steel. The adherend roughness and the adhesive wettability have been characterized before testing. The significant stiffness contrast between the stiff adherends and the soft adhesives promoted homogeneous simple shear creeps. The amorphous adhesive showed creep behaviors that depend on the type of substrates, showing that the joint viscoelasticity could not be predicted knowing the bulk adhesive viscoelasticity only, unlike for stiff adhesives as recently reported in the literature. Finally, the single-lap joint creep behaviors of both adhesives on the same glass adherends were compared and discussed at the light of their different microstructures inducing different mechanical behaviors.

Improvement in compatibility of hot melt pressure-sensitive adhesive with cinnamon volatile oil and in vitro transdermal property by physical blending

Hot melt pressure-sensitive adhesive(HMPSA) has broad application potential in the field of traditional Chinese medicine(TCM) plasters due to its high drug loading, weak skin irritation, satisfactory adhesion, etc. compared with rubber plasters.However, the structure of HMPSA is prone to suffer from the damage caused by volatile oils in TCM plasters. In view of this, a kind of HMPSA with a stable structure was prepared by physical blending of DINCH, polypropylene wax and liquid rubber(LIR) in the present study, which is denoted as DPL. The dosage of cinnamon volatile oil(CVO), the model drug, was selected with viscosity, softening point and cohesion as evaluation indexes. The interaction between DPL and HMPSA was investigated by Fourier transform infrared spectroscopy(FT-IR) and differential scanning calorimetry(DSC). The compatibility of HMPSA with CVO and its transdermal ability were studied by in vitro transdermal test, adhesion, scanning electron microscopy( SEM) and rheological evaluation. The results showed that 5% CVO began to damage the structure of HMPSA. The initial adhesion and holding adhesion of DPL-modified HMPSA(DPL-HMPSA) were not significantly changed compared with those of HMPSA, whereas the 180° peel strength was decreased. FI-IR unraveled that DPL formed the n-π conjugated system with styrene-isoprene-styrene block copolymer(SIS), and there was no significant difference in the glass transition temperature according to DSC results, which indicated the good compatibility of DPL with HMPSA. With 5% CVO loaded, the drug content of DPL-HMPSA was 1. 14 times higher than that of HMPSA, and the decrease rate of drug content in DPL-HMPSA was 16% lower than that in HMPSA after 3 months. SEM demonstrated that CVO did not cause obvious structural damage to DPL-HMPSA. Rheological evaluation revealed that the storage modulus and loss factor of DPL-HMPSA were higher than those of HMPSA, and the cohesion was also stronger. The percutaneous penetration rate of cinnamaldehyde in DPL-HMPSA was 2. 25 times that of HMPSA. In conclusion, DPL-HMPSA had more stable structure, better compatibility with CVO, and higher in vitro transdermal efficiency of cinnamaldehyde than before the modification. This study can provide reference for the mitigation of the matrix structure damage caused by volatile oil components in TCM plasters and the enhancement of the content and in vitro transdermal rate of drug.

Feasibility of Processing Hot-Melt Pressure-Sensitive Adhesive (HMPSA) with Solvent in the Lab

Hot-melt pressure-sensitive adhesive (HMPSA) is an environmentally benign adhesive which is typically processed without solvent in industries. However, casting solution method is commonly used for experimental purposes in the lab for convenience. Therefore, seven types of solvent with different polarities, including toluene as the most commonly used solvent, were investigated in this work to study the feasibilities. Quick bond strength and holding power were tested with different types of solvents and different adhesive weight percent in the prepared solutions. Through viscosity measurement, thermal analysis, and compositional analysis, the correlation between the chosen solvents and adhesive performance was further explored. It was found that the differences in the obtained bond strength of HMPSA treated with a variety of solvents were due to physical reasons instead of chemical reactions, and a solvent with similar polarity to toluene (e.g., tetrachloride, octane) should be considered as an option because a similar polymer chain relaxation could be maintained as the original HMPSA without solvent treatment. In this study, the mechanism of choosing toluene as common solvent for HMPSA testing was analyzed, and the feasibility of optional solvents was discussed.

Synthesis and Characterization of Polyester Derived from Renewable Source and its Application as Tackifiers Resins in Hot Melt Pressure Sensitive Adhesives (HMPSA)

AbstractGlycerol esters are synthesized from rosin of Elliottii type by different methodologies and characterized in relation to the most relevant properties that define their quality for use in adhesive formulations. The produced esters have different properties due to the different synthesis recipes, mainly in relation to the percentage of glycerol and the type of additive used in the esterification. However, all cases showed great potential to be used as tackifiers resins in hot melt pressure sensitive adhesives (HMPSA).

The effectiveness of two types of adhesive for catching insects in traps

Sticky traps for monitoring insects use polybutene adhesive (PBA) to entangle insects. This glue is effective but messy to use and an alternative, hot-melt pressure-sensitive adhesive (HMPSA) is available. The effectiveness of these two adhesives was compared for catching pest and beneficial insects, primarily in apples. Various types of trap with either PBA or HMSPA were placed in orchards and vineyards in Hawke’s Bay and Nelson. Eight pests from six families, six parasitoids, five predators and one pollinator were commonly recorded. Traps with HMPSA generally caught similar numbers or more of both insect pests and beneficial insects than traps with PBA. Traps with HMPSA performed better for larger insects (&gt;1.5 mm), whereas those with PBA tended to be more effective for smaller insects. Both types of adhesive were effective for up to 4 weeks. HMPSA was effective for monitoring a range of insect pests and beneficial insects. Compared with PBA, HMPSA was more consistent and much cleaner and easier to use. It is recommended that HMPSA replaces PBA in traps for monitoring moth pests in the pipfruit industry.

Hot-melt pressure-sensitive adhesives based on SIS-g-PB copolymer for transdermal delivery of hydrophilic drugs

SIS-g-PB copolymers were successfully synthesized by grafting living polybutadiene (PB) lithium macroanions onto epoxidized SIS copolymers. Their molecular structures and thermal properties were characterized by TGA, 1H-NMR and DSC, respectively. SIS, epoxidized SIS (ESIS) and SIS-g-PB copolymers were melt-blended with tackifiers to develop hot-melt pressure-sensitive adhesives (HMPSAs), respectively (named of H-SIS, H-ESIS and H-SIS-g-PB). Their adhesive performances were measured in terms of 180° peel strength and holding power. A modified Franz type horizontal diffusion cell was used to carry out In vitro drug release experiments, in which geniposides were chosen as hydrophilic model drugs. The results showed that H-SIS-g-PB has two times as high a 180° peel strength as H-SIS. Meanwhile H-SIS-g-PB has a slightly lower drug cumulative release rate than H-ESIS. It is indicated that the PB branches not only could impart good adhesive performance to H-SIS-g-PB via improving the compatibility between the epoxidized main chains and tackifier resins but also provide release channels to hydrophilic drugs by retaining most of the epoxide groups in the SIS-g-PB copolymers.

Preparation and properties of polyisobutene/organic montmorillonite hot melt pressure-sensitive adhesive (HMPSA)

ABSTRACTTo enhance the interfacial adhesion between Na-montmorillonite (Na-MMT) and polyisobutene (PIB) matrix, it is necessary to modify Na-MMT in organic way. Organic montmorillonite (OMMT) was successfully modified by Na-MMT with cetyltrimethyl ammonium bromide (CTAB) intercalation reagent. The X-ray diffraction (XRD) result showed that the d-spacing of Na-MMT was increased from 1.424 to 2.480 nm after organic modification. PIB/OMMT hot melt pressure-sensitive adhesive (HMPSA) samples were prepared by melt-intercalation process. The amount of OMMT was optimized according to the system stability and adhesion performance. The effects of OMMT content on rheological, adhesion and thermal properties of PIB HMPSA were investigated. Adhesion performance and system stability of PIB HMPSA were greatly improved by adding moderate amounts of OMMT. In addition, the sample containing 1 wt% OMMT exhibited optimal adhesion property and excellent stability, meanwhile, its 180° peel strength was 1.19 times greater than pristine sample.

Hot-melt pressure-sensitive adhesive for seamless bonding of nylon fabric Part II: Process parameter optimization for seamless bonding of nylon fabric

This study develops hot melt pressure sensitive adhesives (HMPSAs) for the seamless bonding of nylon fabric, using butyl acrylate as the main monomer material and mixing the functional monomer for polymerization. It is combined with 2-10phr diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide for the photoinitiator and ultraviolet irradiation is used to make a pre-polymer. The effects of butyl acrylate content, type of functional monomer, and 2-10phr diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide content on the molecular weight of acrylate pre-polymer are discussed, following the Taguchi method. The pre-polymer is then mixed with the reactive diluent glycidyl methacrylate blend and with 2-10phr diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, coated on a release film, irradiated by ultraviolet light, and cured into hot melt pressure sensitive adhesives. The adhesive properties of hot melt pressure sensitive adhesive bonding on nylon include the peel strength, the shear strength, adhesive warpage, adhesive color difference, and adhesive overflow, which are discussed following the Taguchi method and the elimination and choice translating reality method for multi-quality analysis. Hot melt pressure sensitive adhesives are implemented by optimization parameters for practical validation. The results show that the peel strength of hot melt pressure sensitive adhesives is 1.495 kg/cm, the shear strength of hot melt pressure sensitive adhesives is 14.326 kg/cm2, adhesive warpage is 0.93 mm, adhesive color difference is 1.66, and adhesive overflow is 0.97 mm. The performance of HMPSAs in this study is enhanced effective.

Hot-melt pressure-sensitive adhesive for seamless bonding of nylon fabric part I: effect of a functional monomer

This study synthesized a series of prepolymers from butyl acrylate and functional monomer with various side-chain structures. A bulk polymerization process was then applied under ultraviolet irradiation. The molecular structure of the prepolymer was characterized by Fourier transform infrared spectroscopy and gel permeation chromatography. The degradation temperature and glass transition temperature ( Tg) were examined. The prepolymer was employed to the acrylic hot-melt pressure-sensitive adhesives (HMPSAs) and the corresponding adhesive performance was presented. In this study, glycidyl methacrylate was considered to be an effective cross-linking agent for acrylic HMPSAs containing carboxylic acid groups. The prepolymer containing carboxylic acid synthesized acrylic HMPSAs exhibited high adhesion in peel strength and shear strength compared to the hydroxyethyl group. The adhesive performance of HMPSAs in different environments was also investigated.

Synthesis and structure–property relationships of SIS-g-PB copolymers and their application in hot-melt pressure-sensitive adhesives

Grafting polybutadiene blocks onto epoxidized styrene-b-isoprene-b-styrene (ESIS) copolymers results in significant improvement of ESIS-based adhesives performance while retaining polarity.

SISO-based hot-melt pressure-sensitive adhesives for transdermal delivery of hydrophilic drugs

A monomer-activated anionic polymerization approach was utilized to synthesize poly(styrene-b-isoprene-b-styrene-b-ethylene oxide) tetrablock terpolymers (SISO), which were melt-mixed with tackifiers and plasticizer to develop polar SISO-based hot-melt pressure-sensitive adhesives (HMPSAs) for transdermal delivery of hydrophilic drugs. Their hydrophilic performance was characterized using contact angle analysis. Their adhesive performances were measured in terms of 180° peel strength and holding power. In vitro drug release experiments were carried out using a modified Franz type horizontal diffusion cell, in which geniposide was chosen as a hydrophilic model drug. The results show that poly(ethylene oxide) (PEG) blocks exhibit substantial effects on adhesive performance and the release behavior of the model drug. The shorter PEG molecular chains enhance adhesive performance and the cumulative release rate of the model drug in the SISO-based HMPSAs. The longer PEG molecular chains tend to crystallize. Their crystallization structures have negative effects on adhesive performance and limit the dissolution and diffusion of drugs in the SISO-based HMPSAs. Therefore, appropriate PEG molecular chains are required to fabricate SISO-based HMPSAs with excellent adhesive performance for transdermal delivery of hydrophilic drugs.

Optimization of SIS-based hot-melt pressure-sensitive adhesives for transdermal delivery of hydrophilic drugs

To optimize hot-melt pressure-sensitive adhesives (HMPSAs) for transdermal delivery of hydrophilic drugs, styrene–isoprene–styrene copolymer (SIS), epoxidized SIS (ESIS), tackifiers, and plasticizer were melt-mixed with polyethylene glycol 2000 (PEG2000) or poly (ethyl acrylate-co-methyl methacrylate-co-trimethylammonioethyl methacrylate chloride) (RLPO). Their compatibility was studied with DSC and FT-IR. Their 180° peel strength and holding power was measured for their adhesive performances. In vitro drug release experiments were carried out using a modified Franz type horizontal diffusion cell, in which geniposide was chosen as a hydrophilic model drug. Although PEG2000 can greatly enhance the accumulative release rate of geniposide in a manner of burst release, its poor compatibility with the components of SIS/ESIS-based HMPSAs makes the adhesive performance hardly meet the practical requirement of transdermal drug delivery. RLPO not only provides sustained release behavior to geniposide through its low content of quaternary ammonium groups but also preserves excellent adhesive performance due to its partial compatibility with the components of SIS/ESIS-based HMPSAs. Therefore, RLPO is preferred to develop ideal SIS/ESIS-based HMPSAs for transdermal delivery of hydrophilic drugs.

Preparation and thermal properties of the graphene–polyolefin adhesive composites: Application in thermal interface materials

Graphene mixed with epoxy for thermal interface material (TIM) has been well researched. However, some issues emerge when epoxy is used as matrix material, such as overflow problem, non-uniform thickness, needing solidification time, etc. In order to avoid the above issues, a new high performance phase change material (PCM) is prepared by incorporating graphene with polyolefin hot melt pressure sensitive adhesive (HMPSA). The thermal conductivity and hardness of graphene/HMPSA (GHMPSA) composites are both measured and found to be increased with the increase of filled graphene. Due to the increasing hardness, the smallest thermal contact resistance is achieved with 6wt.% graphene, not 10wt.%, even the biggest thermal conductivity of GHMPSA is 5.6W/(mK) with 10wt.% graphene. The comparison between the present GHMPSA TIM and other commercial TIMs indicates that the present GHMPSA composite is a commendable TIM in reducing thermal contact resistance.

수첨 DCPD계 석유수지를 이용한 SBCs계 핫멜트점착제의 접착성능 연구

Dicyclopentadiene (DCPD)계 석유수지는 많은 분야에서 점착부여수지로 널리 사용되고 있다. 특히, 수소첨가 반응으로 수지 내 이중결합을 수소로 치환시킨 수첨(水添) DCPD계 석유수지는 무색투명의 색상과 빛과 열에 대한 우수한 안정성으로 인해, 고급 핫멜트접착제(hot melt adhesives, 이하 HMAs) 또는 열용융형 감압접착제(hot melt pressure sensitive adhesives, 이하 HMPSAs) 용도에 널리 사용되고 있다. 본 논문에서는 다양한 수첨 DCPD계 석유수지가 SIS와 SBS와 같은 SBCs를 기본 엘라스토머로 사용한 HMPSAs에서 점착부여수지로 사용될 때의 접착성능에 대해 논의하며, 점착부여 수지의 특성과 HMPSAs의 접착성능과의 상관관계를 보여준다. 높은 연화점의 점착부여수지를 사용할 수록 HMPSAs의 <TEX>$T_g$</TEX>, 연화점 그리고 crossover temperature가 높아졌다. 높은 방향족 모노머 함량의 점착부여수지를 사용할 경우에는, PSAs의 crossover temperature 및 연화점 감소로 확인할 수 있듯이 PSAs의 내열온도를 저하시키는 경향을 보였다. Dicyclopentadiene (DCPD)-based hydrocarbon resins are widely used as tackifiers in many applications. In particular, hydrogenated DCPD-based hydrocarbon resins are widely used in premium hot-melt-type adhesives such as hot melt adhesives (HMAs) and/or hot melt pressure-sensitive adhesives (HMPSAs), because are water-white in color and possess excellent stability to light and heat. This article discusses the adhesive performance of various hydrogenated DCPD resins when they are used as tackifiers in styrene-block-copolymer (SBC)-based HMPSAs. This article shows the correlation between the characteristics of tackifiers and the adhesive performance of SBC-based HMPSAs. The higher the softening point of the tackifier, the higher is the <TEX>$T_g$</TEX>, softening point, and crossover temperature of the PSAs. High aromatic H wt% content reduces the high-temperature resistance of PSAs, as suggested by the decrease in the crossover temperature and softening point of the PSAs.

Preparation and characterization of polarity-modulated SIS-based hot-melt pressure-sensitive adhesives

In order to develop polarity-modulated hot-melt pressure-sensitive adhesives (HMPSAs), epoxidation of styrene-isoprene-styrene (SIS) copolymers, using in situ prepared per-formic acid was studied. The polymers were characterized with Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, differential scanning calorimetry, and contact angle tests. The epoxidation degree linearly increases with the epoxidation time without side reaction at low temperature. The polarity of the polymers increases with the epoxidation degree. At low epoxidation degree, the 180° peel strength of epoxidated-SIS-based HMPSA increases with the epoxidation degree. In epoxidated-SIS-based HMPSAs, ESIS plays the role of compatibilizer.

Fabrication of pH sensitive amphiphilic hot-melt pressure sensitive adhesives for transdermal drug delivery system

Based on the blend of styrene-isoprene-styrene (SIS) thermoplastic elastomer and acrylic resin Eudragit® EPO, amphiphilic hot-melt pressure sensitive adhesives (HMPSAs) were fabricated. Compatibility and micromorphology of SIS/EPO blends (SEBs) were analyzed with differential scanning calorimetry (DSC), atomic force microscopy (AFM) and scanning electron microscopy (SEM). The results showed that when the mass ratio of SIS to EPO was 1:1~1:2, bicontinuous structure was formed. Following the addition of an appropriate amount of polyethylene glycol (PEG), mineral oil and C5 resin, the amphiphilic HMPSAs were prepared. Because of the compatibility between SIS and EPO, as well as the hydrogen bond interaction between EPO and PEG, amphiphilic HMPSAs showed good thermostability. The adhesive performance of HMPSAs was measured with 180° peeling strength and holding power. Geniposide and oleanolic acid were used as model drugs to investigate drug release behavior. When the mass ratio of PEG to SEB was 13:30~16:30, the HMPSAs could maintain good adhesion performance and achieve continual release of both hydrophilic and lipophilic drugs. In weakly acidic conditions, the HMPSAs exhibited good hygroscopicity and release profile, it was shown that pH sensitive amphiphilic HMPSAs were more suitable for transdermal drug delivery system (TDDS).