Effect of network morphology on adhesive performance in emulsion blends of acrylic pressure sensitive adhesives

High-gel containing latices and gel-free latex were blended at various weight ratios. The high-gel containing latices was made of poly(2-ethyl hexylacrylate-stat-acrylic acid) and the gel-free latex was made of poly(2-ethyl hexylacrylate-stat-acrylic acid-stat-isobutoxymethyl acrylamide) using semicontinuous emulsion polymerization. Films were cast at room temperature and dried at 121°C for 10 min. Adhesive performance was evaluated in terms of loop tack, peel, and shear holding power. It was found that interlinking the microgels by the linear polymer due to the isobutoxymethyl acrylamide-acrylic acid reaction in the film when heated gave synergistic effects in increasing shear. This interlinking could take place only if the molecular weight between crosslinks (M_c) of the microgels was greater than the entanglement molecular weight of the linear polymer (M_e), and if the weight average molecular weight of the linear polymer (M_w) was greater than 2 × M_e. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2109–2117, 2001     

Unique adhesive properties of pressure sensitive adhesives from plant oils

We report novel insights into the adhesive performance of bio-based pressure sensitive adhesives (PSAs). Three different homopolymers based on renewable fatty acid methyl esters were characterized in terms of their mechanical and adhesive properties. The polymers display the typical dependence of adhesive properties on molecular weight and degree of crosslinking, as quantified by shear modulus, tack and peel measurements. The absolute values of characteristic adhesion parameters are in the range of commercially available petrochemical PSAs. Curing of applied PSA films at elevated temperature results in a pronounced maximum in tack and peel strength at a critical curing time, which corresponds to a change from cohesive to adhesive failure. Thus, demand-oriented tailoring of adhesive properties can be achieved via an appropriate choice of curing time. Moreover, these bio-based adhesives offer improved adhesion on hydrophobic substrates and high water-resistance without any whitening, thus rendering them an attractive alternative to conventional petroleum-based products. These peculiar features are attributed to the high hydrophobicity of the used monomers.     

水性压敏胶低温性能的测试

通过模拟胶带的使用环境,测试市场上常用水性压敏胶低温下的物理性能及使用性能,并与常温性能进行比较,从而建立合理的评价方法,为水性压敏胶的耐低温性能的测试方法提供参考。     

耐高温丙烯酸酯类压敏胶的研究进展

丙烯酸酯类压敏胶（APSA）具有粘接性能优异、耐老化性能好、成本低、性能稳定、合成工艺简单等优点，由于其优异的性能被广泛应用于自黏带、标签、医药、家庭护理、汽车零部件等领域。但目前APSA应用领域仍较窄，大多数产品耐热性较差，不能在高温条件下使用。因此，开发耐高温性能的压敏胶（HTRAPSA）具有重要意义。文章综述了近年来国内外对HTRAPSA的研究进展，重点阐述了提高溶剂型和乳液型APSA耐高温性的相关研究工作。主要改性方法包括引入交联剂改性、引入特殊的改性单体、引入耐高温性物质改性和改进加料方式、聚合工艺、共混改性等方法来提高APSA的耐高温性能。同时，也指出了这些改性方法存在的问题与不足，以及所制备出的HTRAPSA存在的问题，并对今后相关研究的发展进行了展望。     

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.     

Effect of geometry and hybrid adhesive on strength of finger joints of Pinus elliottii subject to humidity and temperature

The optimized bonding of glued finger joints is required for structural and nonstructural applications. The use of nonspecific adhesives, combined with the joint geometry and exposure of joints to humidity and temperature, are factors that can compromise the durability of glued joints. The main objective of this study is the development of cross-linking poly(vinyl acetate) (PVAc) hybrid adhesive to produce nonstructural finger joints of Pinus elliottii with finger lengths of 6.5 and 4.5 mm. The adhesives were produced by emulsion copolymerization of vinyl acetate with n-butyl acrylate with different amounts of N-methylol acrylamide and blended with resorcinol-formaldehyde resin (RF) and aluminum chloride (AlCl₃). The rheological behavior of adhesives was investigated. We found that the joint configuration and the exposition time employed influenced joint strength. The PVAc/RF adhesive showed a thicker bond line and consequent deeper penetration into the pores of the wood as verified by microscopy analysis. Statistically differences in bond strength of the adhesive joints were found with respect to different conditioning times and finger length. The highest values were exhibited by the joints produced with a finger length of 6.5 mm and glued with the hybrid adhesive (AD-4) than that joints produced with a finger length of 4.5 mm.     

耐高温聚丙烯酸酯压敏胶的合成与研究

采用溶液聚合的方法制备了具有良好粘接性能的溶剂型聚丙烯酸酯压敏胶,并探讨了聚合工艺、聚合单体配方等对聚丙烯酸酯压敏胶的物理性能和粘接性能的影响.在此基础上,引入交联剂乙酰丙酮铝、异氰酸酯、耐高温材料硅树脂对压敏胶基胶进行耐高温改性,制得了耐高温性能优异的聚丙烯酸酯压敏胶.研究结果表明:相对较优的聚合条件是软单体丙烯酸异...     

Effect of adhesive thickness on the stringiness of crosslinked polyacrylic pressure‐sensitive adhesives

The effect of adhesive thickness on stringiness behavior during 90° peel testing was investigated for crosslinked poly(n‐butyl acrylate‐acrylic acid) (A) and poly(2‐ethylhexyl acrylate‐acrylic acid) (B) with a constant crosslinker content. The adhesive thickness was varied over the range from 15 to 60 μm. All adhesive thicknesses exhibited sawtooth‐type peeling with a front frame for B, but only the 30‐μm thickness generated a front frame‐type for A. The peel rate decreased from 15 to 45 μm and plateaued above 45 μm under a constant load test. These results indicate that the adhesion strength increases with adhesive thickness, but reaches a constant value at high thicknesses. The stringiness was also analysed for B and the sawtooth interval observed to increase with increasing thickness. This means the sawtooth number decreased. As a result, the concentrated stress per sawtooth induces easier peeling and so this factor tend to increase the peel rate. Conversely, the stringiness width increased with increasing thickness. The stress load over the stringiness region decreased with an increase in thickness, meaning that a decrease in the concentrated stress decreases the peel rate. The actual peel rate is influenced by the contributions of these two factors. The strain rates during constant peel rate tests decreased slightly with increasing thickness, due to a reduction in the apparent modulus. The molecular mobilities near the adherend and the backing surfaces were evidently restrained by these surfaces, and the relative rates of motion of such restrained molecules decrease with increased thickness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42210.     

醋-丙乳液型压敏胶的研发和生产

概述了将增粘树脂和纳米无机粒子引入丙烯酸酯乳液,采用特殊乳化剂和特殊单体合成丙烯酸酯乳液以及在核-壳乳液共聚等方面开展的研究,并就其研制开发成果和工业化生产作了介绍。     

固化温度对缓凝黏合剂固化时间和强度的影响

为研究固化温度对缓凝黏合剂固化时间和强度的影响,将缓凝黏合剂在固化温度分别为25、45、65、85 ℃的条件下养护。通过邵氏硬度试验研究了3种缓凝黏合剂在不同固化温度条件下的固化速率,测试了缓凝黏合剂在不同固化温度条件下的拉伸剪切强度、抗折强度和抗压强度。结果表明,固化温度越高,缓凝黏合剂固化时间越短,以25 ℃为基准,45 ℃条件下的固化时间缩短约50 %,45 ℃以上,温度每升高20 ℃,固化时间缩短约10 %;以25 ℃条件下的强度为基准,缓凝黏合剂在不同固化温度条件下拉伸剪切强度的变化率在6 %内,抗折强度的增加率在6 %~45 %,抗压强度的增加率在9 %~50 %。     

双重改性耐高温丙烯酸酯压敏胶的制备

以丙烯酸酯单体为原料、KH-570(γ-甲基丙烯酰氧基丙基三甲氧基硅烷)和GH(水性多异氰酸酯)固化剂为改性剂,制备了高性能的耐高温丙烯酸酯PSA(压敏胶)乳液,并考察了KH-570掺量、GH掺量对PSA各项性能的影响。研究结果表明:随着KH-570掺量的不断增加,PSA乳液的粒径增大、凝胶率增多且储存稳定性变差,PSA胶膜的表面粗糙度和耐热性呈递增趋势;此外,随着GH掺量或KH-570掺量的不断增加,PSA的高温持粘力增大,但180°剥离强度和初粘力下降。当w(KH-570)=0.3%(相对于总单体质量而言)、w(GH)=0.7%(相对于PSA乳液质量而言)时,PSA的综合性能相对最好。     

耐高温压敏胶粘带的研究进展

综述了近年来国内外在耐高温压敏胶粘带研究开发和应用方面的研究进展,分别对热固型、溶剂型、乳液型、有机硅型、辐射固化型、热熔型等耐热压敏胶粘带作了具体介绍.     

Crosslinked acrylic pressure‐sensitive adhesives. II. Effect of humidity on the crosslinking reaction

The effect of humidity during storage on the crosslinking reactions of isocyanate groups was investigated with attenuated total reflectance Fourier transform infrared spectroscopy with pressure‐sensitive adhesives composed of poly[ethyl acrylate‐co‐(2‐ethylhexyl acrylate)‐co‐(2‐hydroxyethyl methacrylate)] as a base resin and polyisocyanate as a crosslinker. A peak‐resolving analysis of the amide II region revealed four bands. According to an analysis of the Fourier transform infrared spectra of the model compounds, these four bands were assigned to free urethane linkages, hydrogen‐bonded urethane linkages, free urea linkages, and hydrogen‐bonded urea linkages. As expected, storage under humid conditions led to the formation of free and hydrogen‐bonded urea linkages corresponding to the promotion of isocyanate consumption. Peak resolution of the amide II region was found to be a reasonable way of monitoring urethane and urea linkages during crosslinking reactions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3039–3045, 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.     

新型硅改性丙烯酸酯压敏胶的研究

MQ硅树脂可用作改性聚丙烯酸酯类压敏胶,在保持较好力学性能(初粘性、持粘性和剥离强度)和绝缘性的同时,可较大地提高硅改性压敏胶的耐高温性能。MQ树脂的结构和压敏胶的性能用29Si-NMR,DSC,粘性等表征。MQ硅树脂含量对硅改性压敏胶性能影响极大,通常MQ硅树脂用量为(0.3～0.5)%时具有较好的综合性能。该压敏胶粘剂可以直接涂布于经电晕处理的聚酯膜制备压敏胶粘带,便于工业化生产。     

Effect of temperature on the joint strength of a silyl-modified polymer-based adhesive

Temperature is a very important factor that must be fully considered in the study on the adhesive joint strength. In this paper, a silyl-modified polymer-based adhesive ISR 70-08 which is widely used in engineering was studied. Dog-bone specimens were fabricated and tested at ?40°C, room temperature (RT), and 90°C. Results show a decrease in the main mechanical properties with increasing temperature. Butt joints (BJs), single-lap joints (SLJs), and Scarf joints (SJs) were fabricated and tested at different temperatures. A quadratic polynomial expression was an ideal choice to express the joint strength as a function of temperature which was obtained using the least-squares method. Temperature combinations of ?40°C, 0°C, and 90°C were obtained to study the effect of temperature on the joint strength more easily for this adhesive. A three-dimensional surface, consisting of temperature, adhesive angle, and joint strength was presented to facilitate the application of bonding structures in engineering     

Aging and performance of structural film adhesives. III. Effect of humidity on a modern aerospace adhesive

The aging of an uncured, DGEBA-based commercial film adhesive exposed to high humidity at 40°C was monitored by high performance liquid chromatography (HPLC), thermal analysis, solubility, flow, and mechanical testing of joints. DGEBA and brominated DGEBA resins, and representative mixes of these were hydrolyzed in vitro. It is suggested that the major reaction at 40°C is polymerization, which is accelerated by moisture and leads to a crosslinked structure different to that resulting from normal cure. The poorer adhesive performance after aging is mainly the result of reduced resin flow during joint formation, although there is some contribution from the hydrolysis of epoxide groups which leads to lower crosslink density in the cured adhesive. The softening point of the uncured material and T_g of the cured material are useful indicators of the quality of this adhesive which, compared to some earlier formulations, has improved resistance to these conditions.     

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。     

Viscoelastic and adhesive properties of single‐component thermo‐resistant acrylic pressure sensitive adhesives

Poly(butyl acrylate‐vinyl acetate‐acrylic acid) based acrylic pressure sensitive adhesives (PSAs) were synthesized by solution polymerization for the fabrication of high performance pressure sensitive adhesive tapes. The synthesized PSAs have high shear strength and can be peeled off substrate without residues on the substrate at temperature up to 150°C. The PSAs synthesized in the present work are single‐component crosslinked and they can be used directly once synthesized, which is convenient for real applications compared to commercial multi‐component adhesives. The results demonstrated that the viscosity of the PSAs remained stable during prolonged storage. The effects of the preparation conditions such as initiator concentration, cross‐linker amount, organosiloxane monomer amount and tackifier resin on the polymer properties, such as glass transition temperature (T_g), molecular weight (M_w), surface energy and shear modulus, were studied, and the dependence of the adhesive properties on the polymer properties were also investigated. Crosslinking reactions showed a great improvement in the shear strength at high temperature. The addition of tackifier resin made peel strength increase compared to original PSAs because of the improvement of the adhesion strength. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40086.