有机硅压敏胶的性能及影响因素

对有机硅压敏胶的几个影响因素进行了考察,在此基础上研制出一种有机硅压敏胶。乙烯基含量为0.3%的MQ硅树脂和相对分子质量为4.0×105的硅橡胶等比例配合,经1.0%的二丁基二月桂酸锡催化缩合,再以1.5%的BPO交联剂200℃下交联10min制得的有机硅压敏胶性能优异,初黏力25#,室温持黏力960min,剥离强度13.45N/25mm。     

Polymeric reaction of polymer-monomer system irradiated by low energy electron beam. III. Adhesive property of pressure sensitive adhesive

Application of low-energy electron beam to nonsolvent-type pressure-sensitive adhesive is investigated. Adhesive properties such as peel strength, dead load strength, and ball tack were closely related to the reaction behavior (gel fraction and graft efficiency) of the acrylate polymer-monomer system. The reaction behavior is eluciadated by combining the measurements of gel fraction, infrared spectrum of gel, and molecular weight distribution detected by gel permeation chromatogrophy. It was found that the adhesive property of electro beamcured adhesives depends on the molecular weight of added polymer, monomer concentration, and irradiation dose. Graft polymerization and moderate crosslinking by electron beam irradiation especially contribute to superior high adhesive properties.     

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.     

The effect of polymer molecular weight and crosslinking reactions on the adhesion properties of microsphere water-based acrylic pressure-sensitive adhesives

In this work, the effect of polymer molecular weight and crosslinking reactions on the end-use properties of the microsphere water-based acrylic pressure-sensitive adhesives (PSA) is presented. Polymer molecular weight and polymer microstructure were regulated using different chain transfer agent (CTA) concentrations and by addition of a diacrylic monomer (MM). The adhesion properties of the synthesized PSAs were characterized via measurements of tack, peel adhesion and shear strength. The results of experiments have shown that the kinetics of suspension polymerization is relatively independent on the amount of CTA and MM. The amount of gel phase in the adhesive was reduced with increasing amount of CTA agent, and gel phase amount may be considered as a function of polymer molecular weight. With a combination of CTA and MM was possible to regulate the amount of formed gel phase in the adhesive, as well sol phase molecular weight. All of the measured adhesion properties strongly depend on molecular weight of the synthesized polymer and on the amount of gel phase. For adhesives synthesized solely with addition of CTA, tack decreased with lower polymer molecular weight and consecutively also with lower amount of gel phase. The same trend was also observed for peel strength measurements, whereas a cohesive failure was observed for adhesives with low amount of gel phase. A maximum value for tack and shear strength was observed at 80 wt% of gel phase. In case of syntheses with a combination of CTA and MM (amount of gel phase in range from 70 to 80 wt%), tack values were distributed in quite narrow range. On the other hand, peel strength values decreased in comparison with adhesives synthesized only with CTA, regardless to the equal amount of gel phase. Poor shear strength was observed for all adhesives synthesized by combination of CTA and MM.     

Factors affecting initial bond strength in solvent-based contact adhesives

Novel interpretation is given for the development of initial bond strength maximum in solvent-based contact adhesives at particular elastomer/resin ratios in the adhesive films. Complex relations between initial bond strength, tack of adhesive films, adhesive open time, solvent retention, and resin content in adhesive films are discussed. These results are based on data using polychloroprene adhesives modified with butylphenolic resins and also on previous studies with other contact adhesives. It is suggested that solvent retention is the main factor affecting initial bond strength in solvent-based contact adhesives.     

Viscosity and shear strength of natural‐rubber‐based adhesives in the presence of gum rosin and petroresin

The viscosity and shear strength of pressure‐sensitive adhesives based on natural rubber (standard Malaysian rubber grade L) were studied with gum rosin and petroresin as the tackifying resins. Effects of the concentration of the tackifying resin and the molecular weight of rubber on the two properties were systematically investigated. Toluene was used as the solvent throughout the study to prepare the adhesives. The viscosity and shear strength of the adhesives were determined with a rotary viscometer and a texture analyzer, respectively. For the shear test, a hand coater was used to coat the adhesives on the release paper substrate to provide coating thicknesses of 60 and 120 μm. The results indicated that the viscosity increased with the resin loading and molecular weight of rubber increasing. The viscosity of the adhesive prepared from petroresin had a higher value than that of the gum‐rosin‐based adhesive. The shear strength of the adhesives decreased gradually with increasing resin content for both tackifying resins and coating thicknesses, and this observation was attributed to the decrease in the cohesive strength due to the dilution effect of the resins. However, the shear strength passed through a maximum at a molecular weight of rubber of 8.5 × 10⁴ for both resins. The gum‐rosin‐based adhesive consistently showed higher shear strength than that of the petroresin/natural rubber adhesive because of the better cohesiveness and compatibility of the former system. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

可固化性环氧-丙烯酸酯聚合物压敏胶的研究

在丙烯酸酯类单体的乳液聚合过程中加入环氧树脂,可以制得可固化性乳液压敏胶.研究了环氧树脂含量、聚合物的玻璃化温度、聚合工艺等因素对压敏胶主要性能的影响,并通过对交联度的测量,确认了环氧树脂参与聚合交联的事实.实验得出:采用核-壳聚合工艺、当环氧树脂的含量为30%(wt)、共聚物玻璃化温度为243.15K时,制得的可固化性乳液压敏胶的初黏力为9号球,固化后对铝合金的粘接强度可达10MPa.     

Molecular parameters and their relation to the adhesive performance of acrylic pressure‐sensitive adhesives

Model acrylic pressure‐sensitive adhesives (PSAs) based on poly(2‐ethyl‐hexyl acrylate‐stat‐acrylic acid) and poly(n‐butyl acrylate‐stat‐acrylic acid) at 97.5/2.5 wt % were synthesized using semicontinuous emulsion and solution polymerizations. Microgels formed in the lattices retained their discrete network morphology in the film. In contrast, acrylic solution was essentially gel free and crosslinking in the film was provided by the reaction of acrylic acid and post added Al Acetyl Acetonate after solvent evaporation, which led to continuous network morphology. The difference in film network morphology caused significantly lower shear holding power for the film from emulsion PSA compared with that of solvent‐borne film. Unlike shear holding power, loop tack and peel of acrylic PSAs were mainly controlled by the same sol/gel molecular parameters, regardless of emulsion or solution PSAs. The important molecular parameters are sol‐to‐gel ratio, entanglement molecular weight, weight average molecular weight, and to a lesser extent, glass transition temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2230–2244, 2001     

SIS技术参数对其热熔压敏胶性能的影响

研究了SIS的技术参数对SIS热熔压敏胶性能的影响。试验表明,星型结构的SIS热熔压敏胶熔融黏度较低,持粘性、剥离强度较大,软化点较高;嵌段比增大,SIS热熔压敏胶的初粘性降低、持粘性增大、熔融黏度减小、软化点升高;分子质量增大,SIS热熔压敏胶的初粘性降低、持粘性增大、熔融黏度增大、软化点升高;2嵌段SI含量增加,SIS热熔压敏胶初粘性增大、持粘性降低,180°剥离强度先增大后减小,且压敏胶的熔融黏度减小、软化点降低、分切性能变好。     

Molecular structure evolution in peroxide-initiated crosslinking of an ethylene vinyl acetate copolymer and a metallocene polyolefin elastomer

A combination of molecular theories and chemical reaction kinetics was employed to study the molecular structure evolution in the ethylene vinyl acetate and dicumyl peroxide, EVA/DCP, and metallocene polyolefin elastomer, m-POE/DCP crosslinking systems. Premixed EVA/DCP and m-POE/DCP compounds were cured at different temperatures and their gel contents were then measured. The values of crosslinking efficiency were evaluated and were then applied in the theoretical prediction of molecular evolution in a crosslinking process. The molecular weight distributions, gel time, relationships among gel content, degree of conversion, crosslinking density and processing time can all be predicted effectively. Information involving molecular structure evolution provides insights to practical process synthesis and material design.     

单组分交联型丙烯酸酯压敏胶的研制

以丙烯酸酯为原料 ,通过溶液聚合 ,研制成一种单组份交联型丙烯酸酯压敏胶粘剂。研究表明 ,随着交联剂用量从 0 .2 %增大至 1.2 % ,持粘性增大 ,而剥离强度及初粘性下降。在 2 0℃或 60℃下加入交联剂时 ,胶性能没有显著差异。烘烤时间及温度对胶的交联有显著影响 ,12 0℃下烘烤 3分钟 ,交联基本完成。胶液贮存 12 0天后 ,剥高强度仍未下降 ,只是粘度稍有升高。制成的胶带三天后性能就达到稳定状态     

UV crosslinkable microsphere pressure sensitive adhesives—influence on adhesive properties

In the following study, a synthesis and characterization of UV crosslinkable acrylic pressure sensitive adhesives are presented. Different amounts of unsaturated photoinitiator 4-acryloyloxy benzophenone (4-ABF) were added in t-butyl acrylate/2-ethylhexyl acrylate monomer mixture and then polymerized using a suspension polymerization technique. The adhesive suspension was coated on a pilot coating machine, dried by application of IR and subsequently crosslinked under UV light. The copolymerized 4-ABF photoinitiator will produce reactive radicals upon absorption of UV light, which are capable of initiating a rapid chain reaction with neighboring C-H positions of polymer side chains, what leads to formation of crosslinked polymer structures. UV crosslinking process was monitored by ATR-FTIR spectroscopic technique. Adhesion properties of the synthesized materials were determined using standard measurements of tack, peel and shear strength. Results have shown that all adhesive properties are strongly influenced by the degree of crosslinking of the microspheres, which increased with higher amounts of added 4-ABF photoinitiator. All the three measured adhesive properties showed a substantial decrease even at small amounts of added 4-ABF. The decrease in adhesion may be correlated with higher crosslinking density, what also resulted in higher gel phase amounts. Determination of glass transition temperature showed minor difference between adhesive coatings.     

Wood Adhesives Based on Alkaline Extracts from Wastewater Biosolids and Mustard Protein

This work reports on the dry adhesion strength of wood adhesives formulated with fractions of an alkaline extract obtained from wastewater activated sludge, a renewable and abundant resource. The extract was fractionated and desalted using ultrafiltration techniques. The effect of molecular weight and composition (protein and carbohydrate content) on the extract’s adhesion strength was assessed, as well as the effect of crosslinking using glutaraldehyde. The dry adhesion strength of adhesives formulated with soluble mustard seed protein isolate, a protein-rich alkaline extract, is also reported. In the presence of glutaraldehyde, an extract fraction with high protein content and low salt and hydroxide content showed adhesion strength close to that of the mustard protein adhesive and a commercial wood adhesive. It was further determined that the adhesion strength of the extract and its fractions was strongly correlated with their protein content.     

Synthesis,characterization, and pressure‐sensitive properties of butyl acrylate and methyl acrylate copolymers

Butyl acrylate and methyl acrylate copolymers were prepared and evaluated as pressure‐sensitive adhesives. The effects of polymerization conditions such as the temperature, time, amounts of the monomers, and feeding method on the molecular weight, molecular weight distribution, and composition of the resultant copolymers were investigated. The adhesive properties were evaluated in terms of the viscosity, peel strength, and hold time. The best molar ratio of methyl acrylate in the copolymer was 0.466 for pressure‐sensitive adhesives. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1535–1542, 2006     

乳液型丙烯酸酯压敏胶的研制

采用乳液聚合制备了乳液型聚丙烯酸酯压敏胶,讨论了软单体的用量、硬单体用量、交联单体的种类及用量、引发剂的用量、交联剂的用量和乳化剂的配比对压敏胶性能的影响。实验表明,在相同的条件下,丙烯酸的改性效果比丙烯酸羟乙酯好,当m（EHA）∶m（VAc）=82∶10时,压敏胶的综合性能最佳。交联剂的加入明显提高了剥离强度,当其质量分数为0.3%时,剥离强度达到357.33 N/m。     

Silicone resin synthesized by tetraethoxysilane and chlorotrimethylsilane through hydrolysis–condensation reaction

Silicone pressure‐sensitive adhesives compositions contain a polydimethylsiloxane and a silicone resin, which can enhance the instant bonding ability and bonding strength of the adhesive. In this study, silicone resin was designed to have a low molecular weight and a highly nonpolar chemical structure. The silicone resin was applied to silicone pressure‐sensitive adhesives. The molecular structure of silicone resin was characterized by FT‐IR, GPC, ¹H‐NMR, and ²⁹Si‐NMR spectroscopic techniques. Properties such as thermal stability, solubility, hydrophobic, and transparent properties were researched and compared. When the chlorotrimethylsilane increased, it appeared that the amount of silanol groups, molecular weight and thermal stability decreased, while the hydrophobic and transparent properties increased. The silicone resin was completely soluble in toluene and xylene. It was also applied to silicone pressure‐sensitive adhesives, resulting in good peel adhesion. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40317.     

一种无溶剂型双组分聚氨酯胶粘剂的研制

以聚醚多元醇(PPG)、碳化二亚胺-脲酮亚胺改性4,4′-二苯基甲烷二异氰酸酯(MDI-100LL)、多亚甲基多苯基多异氰酸酯(PAPI)和3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)为主要原料,制备出一种双组分无溶剂聚氨酯(PU)胶粘剂。研究了PPG对胶粘剂黏度、交联剂对固化速率的影响,并测试了双组分不同配比时胶粘剂的性能。结果表明:采用高相对分子质量的PPG能显著降低胶粘剂的黏度;交联剂含量与固化速率成正比;调节双组分的配比,可以制备出满足不同施工要求的胶粘剂;固化后胶膜的玻璃化转变温度(T_g)达到-45.6℃。     

Molecular dynamics study of the mechanical properties of polydisperse pressure-sensitive adhesives

Amorphous polymers are one of the primary materials used in pressure sensitive adhesives (PSAs). Their design can be aided by a better understanding of the mechanisms governing the molecular and mesoscopic scale behavior. This work presents a molecular dynamics study of the toughness and failure modes of a coarse-grained polydisperse PSA model in probe peel tests, achieved by varying the crosslinking density and locations. Generally, the toughness of polydisperse PSAs increases at a crosslinking density of 0.5%, compared to the non-crosslinked structure, and declines at higher crosslinking densities, which also changes the failure mode from cohesive to adhesive. The performance is affected by the length of the polymer chains that form crosslinks, although high crosslinking densities make the system less sensitive to effects related to its polydispersity. The results herewith presented display an optimal performance when 35–45% of the particles in the system belong to the giant component of the PSA network. This is achieved at crosslinking densities of 0.5–1.0%, depending on the length of the chains that are allowed to crosslink.     

一种新型可生物降解聚酯压敏胶的制备与性能

以丁二酸、己二酸、1,3丙-二醇、1,4丁-二醇为单体,C-94为催化剂,丙三醇为交联剂,制备了一种新型的、可生物降解的四元无规共聚酯压敏胶,使用核磁共振波谱仪测定了共聚酯中各单元的组成比例,并对其黏弹性、初黏性、持黏性、180°剥离强度等进行了表征,考察了交联剂用量对压敏胶性能的影响。实验结果表明,丙三醇质量分数为0.6%时,压敏胶性能较佳。     

Adhesion Performance and Thermal Stability of Fluorinated PSAs as a Crosslinking System

The use of pressure sensitive adhesives (PSAs) is becoming increasingly popular in many industrial fields. In the automobile industry the main reasons for using PSAs are that they reduce the overall weight of the vehicles and because they are easy to use. However, in the case of acrylic PSAs, the non-crosslinked linear chains results in low thermal stability. In this study, a fluorinated acrylic pressure sensitive adhesive was synthesized under UV irradiation and crosslinking was applied to the linear chain of acrylic PSAs to improve the thermal stability. The adhesion performance was evaluated by analyzing the peel strength, probe tack and shear adhesion failure temperature (SAFT) as a function of the type of crosslinking system. In particular, the peel strength and probe tack were measured at 25, 50 and 80°C. The viscoelastic properties, which were measured using an advanced rheometric expansion system (ARES), revealed a proper balance between the thermal stability and adhesion performance.