Adhesion properties of pressure-sensitive adhesives prepared from SMR 10/ENR 25, SMR 10/ENR 50, and ENR 25/ENR 50 blends

The adhesion properties, i.e. viscosity, tack, and peel strength of pressure-sensitive adhesives prepared from natural rubber/epoxidized natural rubber blends were investigated using coumarone-indene resin and toluene as the tackifier and solvent respectively. One grade of natural rubber (SMR 10) and two grades of epoxidized natural rubbers (ENR 25 and ENR 50) were used to prepare the rubber blends with blend ratio ranging from 0 to 100%. Coumarone-indene resin content was fixed at 40 parts per hundred parts of rubber (phr) in the adhesive formulation. The viscosity of adhesive was measured by a HAAKE Rotary Viscometer whereas loop tack and peel strength was determined using a Lloyd Adhesion Tester operating at 30 cm/min. Results show that the viscosity of the adhesive passes through a minimum value at 20% blend ratio. For loop tack and peel strength, it indicates a maximum at 60% blend ratio for SMR 10/ENR 25 and SMR 10/ENR 50 systems. However, for ENR 25/ENR 50 blend, maximum value is observed at 80% blend ratio. SMR 10/ENR 25 blend consistently exhibits the best adhesion property in this study, an observation which is attributed to the optimum compatibility between rubbers and wettability of adhesive on the substrate. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

丙烯酸酯PSA环形初粘力影响因素研究

以反应型乳化剂(DNS-86)/阴离子型乳化剂(2A1)为复合乳化剂、甲基丙烯酸(MAA)与甲基丙烯酸羟乙酯(HEMA)为极性单体和正十二硫醇为链转移剂时,采用单体预乳化法和半连续乳液聚合法制备丙烯酸酯PSA(压敏胶)乳液。考察了PSA胶带的基材、干胶厚度、烘干条件、复合乳化剂、极性单体和链转移剂等对环形初粘力的影响。结果表明:当基材为白色BOPP(双向拉伸聚丙烯)薄膜、干胶厚度为50μm、烘干时间为3 min、烘干温度为110~115℃、w(正十二硫醇)=0.09%、同时引入MAA和HEMA极性单体、w(复合乳化剂)=1.5%和m(2A1)∶m(DNS-86)=2∶1时,相应丙烯酸酯PSA乳液的环形初粘力相对最大(14.73 N/25 mm)。     

油墨粘着性与纸张拉毛阻力关系的研究

用７种纸张与８种油和油墨结合进行拉毛的研究发现，对于一定纸张，在印刷中发生拉毛时，与其临界拉毛速度相对应的油或油墨的临界Ｔａｃｋ值为一常数，而临界拉毛速度与油墨粘度的乘积（ＶＶＰ值）并非一个常数。油或油墨的Ｔａｃｋ值随印刷速度的增加而增加。临界Ｔａｃｋ值度量了纸张拉毛阻力的大小，Ｔａｃｋ值与速度的关系度量了油墨拉毛强度的大小。     

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.     

Influences of debonding rate and temperature on tack properties and peel behavior of polyacrylic block copolymer/tackifier system

The influences of debonding rate and temperature on the peel behavior of polyacrylic block copolymer/tackifier system were investigated. Poly(methyl methacrylate)-block-poly(n-butyl acrylate)-block-poly(methyl methacrylate) triblock copolymer (MAM) with hard block contents of 23 (MAM-23) and 16 wt.% (MAM-16) and a 1/1 blend with a diblock copolymer (MA) consisting of the same components (MAM-23/MA, total hard block content of 15 wt.%) were used as the base polymer. A special rosin ester was used as a tackifier at various contents in the block copolymer/tackifier system. The peeling process at the probe/adhesive interface during probe tack testing was observed using a high-speed microscope at 23 °C with debonding rate of 10 mm/s. Three different peeling mechanisms were observed. Type A, where peeling progressed linearly from the edge to the center of the probe without cavitation (MAM-23). Type B, where peeling progressed linearly from the edge to the center of the probe with cavitation (MAM-16). Type C, where cavitation occurred over the entire adhesive layer, and peeling initiation was delayed (MAM-23/MA). The peel behavior of MAM-23 changed from Type A to Type B with a decrease of the debonding rate (1 mm/s) or increase of the temperature (40 °C). In contrast, there was no change for MAM-16 and MAM-23/MA. Cavity formation in an adhesive layer restrains peeling; therefore, it is desirable for improvement of the adhesion strength. The tack properties increased with the tackifier content, and the formation of cavitation was less than that for the systems without the tackifier.     

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.     

Photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) by the use of selected photoinitiators type I

This study investigated the photocrosslinking of solvent-based acrylic pressure-sensitive adhesives (PSA) containing selected photoinitiators type I, known as α-cleavage photoinitiators. Photocrosslinking of PSA, especially of acrylic PSA, is well established crosslinking process using the UV radiation technology. UV-initiated crosslinking of acrylic PSA allows the synthesis of the wide range of UV-crosslinkable PSA with the interesting features. Especially, the important balances of properties such as adhesive and cohesive strength which are typically critical for the application performance can be achieved by this technology. The selection of suitable photoinitiator plays an important role to obtain the optimum properties of acrylic PSA including tack, peel adhesion, and shear strength. In this study, the investigations on different saturated conventional photoinitiators of type I for solvent-based PSA were carried out. The effects of photoinitiator concentration, UV crosslinking time and UV dose on the tack, peel strength, and shear strength were explored in detail for guiding the choice of photoinitiators to fabricate advanced PSA for industrial usage.     

Elastic Analysis of the Loop Tack Test for Pressure Sensitive Adhesives

The behavior of pressure sensitive adhesive (PSA) tapes is sometimes examined via the loop tack test, in which a loop of the tape is brought into contact with a flat surface and then pulled away. A numerical analysis of the test is presented here. The loop is treated as an elastica, but with a nonlinear moment-curvature relation, so that the material is assumed to be elastic and inextensible. Debonding at the edge of the contact region is assumed to occur when the adhesive reaches a critical elongation. This elongation is assumed to depend on the maximum contact pressure and, in part of the results, on the length of time of contact. Shapes of the loop and values of the corresponding forces are obtained using a shooting method, and the effects of the stiffness and thickness of the adhesive and backing are examined.     

Role of isophorone diisocyanate in the optimization of adhesion tendency of polyurethane pressure sensitive adhesives

The present work describes the role of accurate selection of diisocyanate on the adhesion strength of polyurethanes (PUs). The concentration of diisocyanate induces the hard segment (HS) in the main architecture of PUs which decides the viscoelastic properties of the polymers. A balanced ratio of viscoelastic properties ultimately determines the adhesion strength. The composition of the polymers consists of a blend of macrodiol of hydroxyl-terminated polybutadiene and polypropylene glycol with different molecular weights. Isophorone diisocyanate (IPDI) is used to develop the urethane linkages by maintaining its contribution from 28 to 67% as HS contents. It determines the adhesion strength of the final product. The adhesion strength is evaluated by texture analyzer and 180° peel test. The probe tack analysis shows maximum adhesion energy of 156.2 J cm⁻² and 180° peel test shows 18.80 N/25 mm peel force. The glass-transition (T _g) values obtained through differential scanning calorimetry are in good agreement with theoretically calculated Flory–Fox temperature. The proportion of the loss tangent to the storage modulus (tan δ/E′) shows the optimum value of 2.80 MPa⁻¹. The ideal concentration of IPDI results to achieve better adhesion properties of PU pressure sensitive adhesives. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47124.     

粘层材料剪切疲劳特性及层间设计方法研究

沥青路面的性能及使用年限很大程度上取决于其结构层间粘结状态的好坏。在进行沥青路面设计时,路表弯沉及沥青面层层底拉应力通常被视为重要的设计指标,而沥青路面层间剪切疲劳破坏却被忽视,为沥青路面病害的产生埋下隐患。通过系统的沥青路面层间剪切疲劳试验建立了沥青路面层间剪切疲劳方程及疲劳寿命预估模型,并根据沥青路面的实际工作状态,对该模型进行了修正。提出了基于剪切疲劳破坏的沥青路面层间设计方法,结合工程实例,对沥青路面剪切疲劳破坏进行了验算及寿命预估。结果表明:在以传统的路表弯沉及沥青面层层底拉应力为设计指标时,其层间接触不能满足路面剪切疲劳的要求,因此,建议在沥青路面设计中增加沥青层间剪切疲劳设计指标。