Synthesis of acrylate polymers by a novel emulsion polymerization for adhesive applications

Pressure‐sensitive adhesives (PSAs) are viscoelastic–elastomeric materials that can adhere strongly to solid surfaces with light contact pressure and a short contact time. Polyacrylates produced by solution polymerization are used widely because of their good adhesive properties. A novel emulsion polymerization was established to improve the low physical properties of PSA on the basis of conventional poly(n‐butyl acrylate) (PBA) by emulsion polymerization. PBA latex was synthesized by the emulsion polymerization of 50 wt % n‐butyl acrylate mixed with 15 wt % ethyl acetate (EA) with Emal‐10P and Emulgen‐920 as anionic and nonionic surfactants, respectively, at 70°C. Potassium persulfate (KPS) or a combination of KPS and dicumyl peroxide (DCP) was used as the initiator. The KPS/DCP system gave a very high‐molecular‐weight PBA of a narrow molecular weight distribution with a weight‐average molecular weight/number‐average molecular weight value of 1.01–1.03 in 15 min. The PSA tape was prepared by the casting of the PSA latex onto a corona poly(ethylene terephthalate) film as an adherent to obtain a 50‐μm‐dry‐thickness film. The PSA tape produced from PBA by the novel emulsion polymerization showed better adhesive properties, such as 180° peel adhesion, shear holding power, and rolling ball tack tests according to JIS and ASTM standards, than PSA tape produced from solution polymerization. The occlusion of a small amount of EA in emulsion particles before polymerization was found to give higher properties than those of PBA prepared by the addition of EA to the PBA latex after polymerization. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:413–421, 2006     

乳液聚合中的反应型乳化剂研究进展

介绍了反应型乳化剂的最近研究进展,并简述了其结构、分类和特点。探讨了可聚合乳化剂应用效果的几个影响因素和最佳可聚合乳化剂行为。对设计和使用可聚合乳化剂具有一定的指导作用。     

新型可聚合乳化剂及其在乳液聚合中应用

综述了可聚合乳化剂的分类、性能与应用,比较了可聚合乳化剂与传统乳化剂在乳液聚合中的优缺点,讨论了可聚合乳化剂的溶液性能,指出了可聚合乳化剂的发展趋势。     

反应性乳化剂及其在乳液聚合中的应用研究进展

综述了反应性乳化剂在乳液聚合中应用,以及目前研究现状,详细介绍了烯丙基类、丙烯酸类、丙烯酰胺类、苯乙烯类、马来酸类五种反应性乳化剂最新进展,并对其在实际生产中应用做了详细介绍。     

乳化剂在水性环氧-丙烯酸酯杂化乳液合成中的应用

以水性环氧-丙烯酸酯杂化乳液为基料制备环保型防腐涂料,在制备过程中乳化剂的选择与用量对涂料性能的影响非常关键。主要研究乳化剂种类和用量对环氧树脂改性丙烯酸酯杂化乳液性能的影响。     

Water‐soluble/dispersible cationic pressure‐sensitive adhesives. II. Adhesives from emulsion polymerization

In our previous work, we reported that cationic water‐soluble pressure‐sensitive adhesives (PSAs) could be synthesized in ethanol or methanol. These cationic water‐soluble adhesives would not cause a stickies problem during paper recycling and can be easily removed from the papermaking system by adsorbing on wood fibers. In this study we report the synthesis and application of water‐based cationic PSAs using miniemulsion polymerization. A redox initiator system of cumene hydroperoxide/tetraethylenepentamine was used to force interfacial polymerization. The end‐use properties of the PSAs were evaluated, and the repulpability of the PSAs in paper recycling was studied. It was found that the cationic PSA from miniemulsion polymerization itself was insoluble and nondispersible in water during the paper recycling process. However, if this water‐insoluble cationic PSA from miniemulsion was formulated with a water‐soluble cationic PSA made from ethanol, the solubility or dispensability of the former PSA in water was improved. The molecular weight and degree of crosslinking of the PSA polymer have significant effects on the properties and dispersability of PSA. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 347–353, 2004     

Control of structure and tack properties of acrylic pressure‐sensitive adhesives designed by a polymerization process

Free radical emulsion polymerization of methyl methacrylate (MMA) and 2‐ethylhexyl acrylate (EHA) results in the synthesis of pressure‐sensitive adhesives (PSAs) with good tack properties. Management of both the copolymer composition and the polymerization process allows one to control the behavior of the PSA. Semicontinuous (SC) processes create polymer particles whose instantaneous composition is close to that of the feed particle The SC Mixture process (continuous feeding with comonomer blends) affords nearly homogeneous latex particles and PSA films. The SC Gradient process (separate feedings at inversely varying rates) affords heterogeneous particles and films. The Batch process leads to somewhat heterogeneous films, but the hard (MMA‐rich) microdomains are made compatible with their soft (EHA‐rich) matrix because of the assumed formation of tapered‐type copolymers. Tack measurements indicate the importance of the particle and film structures. Too much hardness or softness leads to unacceptable lacks of adhesion and cohesion, respectively. Homogeneous structures prove adequate, but their tack properties collapse with rising temperature. Heterogeneous structures, with extensive phase segregation, prove unsatisfactory because they lack adhesion and cohesion. Finally, the association of well‐balanced composition and compatible heterogeneity is the criterion for suitable PSA behavior. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2749–2756, 2003     

乳化剂对有机硅改性丙烯酸酯乳液性能的影响

以丙烯酸酯、八甲基环四硅氧烷为主要原料，阴离子型和非离子型表面活性荆为复合乳化荆，通过种子乳液聚合法制备了有机硅改性丙烯酸酯乳液；由透射电子显微镜可观察到乳胶粒子呈明显的核壳结构。讨论了乳化荆种类及用量对聚合反应及反应体系稳定性、乳液稳定性、乳胶粒子的粒径及形态、聚合反应转化率、乳液粘度的影响。结果表明，复合乳化剂中阴离子型与非离子型乳化荆的质量比为2：1时最好．乳化剂的最佳用量为4％．     

聚氨酯预聚体——可聚合乳化剂用于MMA乳液聚合动力学及聚合稳定性研究

将合成的聚氨酯预聚体可聚合乳化剂（APUA）用于甲基丙烯酸甲酯（MMA）乳液聚合体系中，研究了不同引发剂体系和乳化剂对聚合体系的聚合稳定性和动力学影响，并与SDS乳化剂进行了对照。结果显示，用油溶性引发剂（AIBN）和水溶性引发剂（K2S2O8）都能引发该体系的聚合反应，而且聚合速率和转化率都相当高。用AIBN作引发剂时，APUA和SDS两种乳化所对应的动力学曲线不同，但APUA比SDS的聚合速率大得多，其分别类似于微乳液聚合（miniemulsion)和微悬浮聚合（microsuspention)，且聚合过程中会产生一定的凝胶。当乳化剂APUA用量适合时，凝胶量极少，聚合体系是稳定的；而当用K2S2O8作引发剂时，两乳化剂对应动力学曲线相似，聚合过程不产生凝胶。但当引发剂用量较大并以APUA作乳化剂时，在聚合过程中会出现全部粒子突然粗化现象，而以SDS作乳化剂没有出现这一现象。     

Acrylic pressure‐sensitive adhesives with nanodiamonds and acid–base dependence of the pressure‐sensitive adhesive properties

A high performance and functional properties in pressure‐sensitive adhesives (PSAs) are attractive in fundamental and industrial fields. To control the performance of PSAs, nanofillers have been loaded into them. In this study, we focused on composites of acrylic PSAs and nanodiamonds (NDs). The loaded NDs reinforced the mechanical properties and increased the performance of the PSAs. NDs in a PSA formed a network structure. In this study, we revealed that the acidic–basic state was a key factor in the control of the dispersion of the NDs. When a PSA emulsions and ND aqueous dispersion was mixed under basic conditions, the composites demonstrated higher PSA properties (tack, holding, and peeling strength). We investigated the effect of the ND loading on the PSA properties from the viewpoints of the nanostructure and acid–base interactions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46349.     

Influence of polymer microstructure on the performance of post‐treated latex‐based pressure sensitive adhesives

Latex‐based butyl acrylate (BA)/acrylic acid (AA)/2‐hydroxyethyl methacrylate (HEMA) pressure sensitive adhesive (PSA) films with various microstructures were heated to improve their performance. The treated PSA films showed significantly better performance than original latex‐based PSA films with similar polymer microstructures. The effect of the heat treatment depended on the polymer microstructure of the untreated PSA films (or corresponding latices). Decreasing the amount of very small sol polymers (i.e., M_x < 2M_e) in gel‐free untreated PSA films, or both very small (i.e., M_x < 2M_e) and very large sol polymers (i.e., M_x > 20M_e) in gel‐containing untreated PSA films led to treated PSA films with significantly better performance. (Note: M_e is the molecular weight between two adjacent entanglement points in a polymer material.) In addition, simultaneously increasing the sol polymer molecular weight (M_w) as well as the size of the chain segments between two adjacent cross‐linking points (M_c) of the gel polymer in the original PSAs resulted in treated PSA films with better performance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

不同可聚合乳化剂对丙烯酸酯乳液性能的影响

使用3种可聚合乳化剂制备了水基胶粘剂用丙烯酸酯乳液。考查了可聚合乳化剂与单体间的共聚性能,比较了各乳化剂用量对丙烯酸酯乳液的固含量和单体转化率、乳液稳定性(聚合稳定性、贮存稳定性、冻融稳定性)以及乳胶膜的耐水性等性能的影响。结果表明,乳化剂1-烯丙氧基-3-(4-壬基苯氧基)-2-丙醇聚氧乙烯(10)醚(ANPEO10)、烯丙氧基壬基酚聚氧乙烯(10)醚双磷酸(ANPEO10-P2)和烯丙氧基壬基酚聚氧乙烯(10)醚硫酸铵(DNS-86)均成功地聚合到丙烯酸酯聚合物中。用3种乳化剂制备的乳液性能各有特点。使用DNS-86以及ANPEO10-P2制得的乳液的贮存稳定性好;用ANPEO10制得乳液的冻融稳定性最好;使用DNS-86制得的乳胶膜的耐水性最好。3种乳化剂用量均为2.0%时,制得的乳液综合性能最好。     

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。     

Effect of mixing ratio of anionic and nonionic emulsifiers on the kinetic behavior of methyl methacrylate emulsion polymerization

Emulsion polymerization of methyl methacrylate was carried out using a mixture of anionic emulsifier, sodium dodecyl sulfate (SDS) and nonionic emulsifier, poly(oxy ethylene) nonyl phenyl ether with an average of 40 oxy ethylene units per molecule (NP-40). The rate of polymerization and the number of polymer particles produced both increased with increasing the amount of NP-40 initially charged, when NP-40 was used as the sole emulsifier. Interestingly, however, both the rate of polymerization and the number of polymer particles produced was found to decrease, when the amount of NP-40 added to the fixed amount of SDS is increased in the mixed emulsifier. On the contrary, they both increased when the amount of SDS added to the fixed amount of NP-40 is increased in the mixed emulsifier. The mixed emulsifier did not affect the number of the radicals per polymer particle at a certain number of polymer particles, but affected the number of polymer particles, thus the rate of polymerization.     

Semicontinuous emulsion polymerization of vinyl acetate: Effect of ethoxylation degree of nonionic emulsifiers

Poly(vinyl acetate) latices were prepared in the presence of an ammonium persulfate initiator, 10–50 mol of an ethoxylated nonylphenol nonionic emulsifier, and a poly(vinyl alcohol) colloid stabilizer by applying semicontinuous emulsion polymerization (delayed monomer and initiator addition process) in a laboratory scale similar to industrial practice. Two approaches were applied: the molar concentration of the nonionic emulsifier was kept constant and the weight ratios in the polymerization recipe varied or the weight ratios were kept constant. The effects of the change in the ethoxylation degree of the emulsifier to the final latex viscosity, average polymer molecular weight, polymer grafting degree, surface tension of the latex, and the surface free energy of the dried films were investigated. It was determined that the resultant latex viscosity decreases and the viscosity‐average polymer molecular weight increases with increase of the nonionic emulsifier ethoxylation degree. The increase of the ethoxylation degree does not seriously affect the surface tension of the resultant latex or the surface free energy of the dried poly(vinyl acetate) films. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 844–851, 2002     

Secondary dispersion‐based reactive pressure‐sensitive adhesives with improved tack

Reactive pressure‐sensitive adhesives (PSA) have to meet the requirements for sufficient tack prior to crosslinking but also high shear after crosslinking. This article examines the use of secondary acrylic dispersions with reactive groups and epoxy resin dispersions for such PSA. Long‐term stable secondary PSA dispersions with high tack after film formation were obtained. Tack was dependent on the amount of carboxylic acid groups in the polymer as well as the base used for partial neutralization of the solvent‐borne copolymers. Reactive PSA were prepared by mixing a secondary dispersion with high amounts of carboxylic acid groups with an epoxy resin dispersion providing no tack. Variation of mixing ratio gave reactive PSA with sufficient tack, peel, and shear prior to crosslinking. Crosslinking of these reactive PSA at elevated temperatures led to high shear which was limited by incomplete molecular mixing of both phases. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46315.     

Effects of polymeric emulsifiers on the properties of acrylic emulsion pressure‐sensitive adhesives

A series of polymeric emulsifiers was polymerized with 2‐ethylhexyl acrylate, butyl acrylate, and acrylic acid. The polymeric emulsifiers were used to make emulsion copolymers of 2‐ethylhexyl acrylate, butyl acrylate, and acrylic acid. The average particle size of the synthesized emulsions was around 145 nm and the size distribution was very narrow. Also, the emulsions showed good freeze–thaw stability and adhesion properties. The peel strength and holding power of the emulsions were investigated by changing the composition and molecular weight of the polymeric emulsifier. The results show that the peel strength exhibits a maximum at particular molecular weight and acrylic acid content of the polymeric emulsifier, while the holding power increases with molecular weight. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1456–1460, 2004     

丙烯酸酯压敏胶的研究进展

概述了近年来各种丙烯酸酯类PSA(压敏胶)的研究进展,重点介绍了乳液型、溶剂型、热熔型和辐射固化型丙烯酸酯类PSA的制备工艺及应用性能。最后对丙烯酸酯类PSA的发展方向进行了展望。     

聚合工艺对丙烯酸酯乳液胶粘剂性能的影响

主要研究了聚合工艺对丙烯酸酯乳液胶粘剂性能的影响 通过对乳液胶粘剂的各种性能测试,发现3种聚合方法中,种子乳液聚合法制备的乳液胶粘剂的综合性能较为理想 采用种子乳液聚合法,最佳聚合工艺为:单体的滴加时间4h、聚合温度50℃、搅拌速率80 r/min