Effect of adhesive thickness on the wettability and deformability of polyacrylic pressure‐sensitive adhesives during probe tack test

Effect of adhesive thickness on the wetting and deformation behaviors during probe tack test of pressure‐sensitive adhesive (PSA) was investigated. For this purpose, cross‐linked poly(n‐butyl acrylate‐acrylic acid) [P(BA‐AA)] and poly(2‐ethylhexyl acrylate‐acrylic acid) [P(2EHA‐AA)] random copolymers with an acrylic acid content of 5 wt % and thicknesses in the range of ～15–60 μm were used. Tack was measured using the probe tack test and the fracture energy was calculated from the areas under force–displacement curve recorded during debonding process. From contact time dependence of fracture energy, the rising rate of fracture energy with contact time increased with increasing of adhesive thickness and was P(2EHA‐AA) > P(BA‐AA). The fracture energy was P(BA‐AA) > P(2EHA‐AA) at shorter contact time, whereas it reversed at longer contact time. This was caused by two different interfacial adhesions: the physical wetting of PSA molecules to the adherend surface with contact time and the chemical interaction between the acrylic acid units and the adherend surface. From the force–displacement curve measured under the condition of sufficient interfacial adhesion, both maximum force and displacement—namely, the deformability of PSA during debonding process—increased with adhesive thickness. The degree of increase of deformability was P(2EHA‐AA) > P(BA‐AA). The fracture energy was found to depend on the development of interfacial adhesion during contacting process and the deformability of PSA during debonding process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43639.     

环保型阻燃丙烯酸酯压敏胶的制备与性能研究

以自制环三磷腈单体——(2-烯丙基苯氧基)五苯氧基环三磷腈(APPCP)为阻燃剂,丙烯酸丁酯(BA)和丙烯酸异辛酯(EHA)为软单体、甲基丙烯酸甲酯(MMA)为硬单体、丙烯酸(AA)和甲基丙烯酸(MAA)为交联单体,采用共聚法制备出一种新型丙烯酸酯PSA(压敏胶)。研究结果表明:当m(BA)∶m(EHA)∶m(MMA)∶m(AA)∶m(MAA)=62.5∶18.8∶6.2∶7.5∶5.0、w(APPCP)=10%时,PSA的综合粘接性能相对最好,并且其起始热分解温度超过200℃,600℃时残炭率超过10%,燃烧等级(UL-94)达到VTM-0级,极限氧指数(LOI)为27.9%,完全满足环保型无卤阻燃丙烯酸酯PSA的使用要求。     

Segregation Behavior Found in Poly(2-ethylhexyl acrylate)/Poly-(vinylidenefluoride-co-hexafluoro acetone) Blends

The surface and bottom compositions of poly(2-ethylhexyl acrylate) (P2EHA)/poly-(vinylidene fluoride-co-hexafluoro acetone) [P(VDF-HFA)] blends were investigated by XPS analysis. In these blends, the enriched P(VDF-HFA) layer was observed from the top surface to a few nm depth, while the P2EHA component segregated at the bottom (the surface in contact with release liner). The probe tack values of the bottom side were remarkably larger than those of the surface side for the P2EHA/P(VDF-HFA) blends because the characteristic segregation structure was formed. We expected that the P2EHA/P(VDF-HFA) blends could be utilized as a non-backing pressure sensitive adhesive (PSA) tape. The effects of the film thickness of the blends and the molecular weights of P2EHA on the segregation structure were also examined. We thought that segregation behavior found in P2EHA/P(VDF-HFA) blends was caused by several factors, such as surface tension, miscibility, density, and rate of solvent casting.     

单组分溶剂型丙烯酸酯压敏胶的研制

采用丙烯酸异辛酯、丙烯酸丁酯、丙烯酸、醋酸乙烯酯、甲基丙烯酸甲酯和甲基丙烯酸缩水甘油酯等为原料,通过接枝聚合制备了一种单组分溶剂型丙烯酸酯压敏胶。探讨了干燥时间和温度、交联剂用量对该压敏胶性能的影响。考查了加入交联剂后压敏胶及其产品的性能稳定性。结果表明,当交联剂用量为0.6%时,可以获得综合性能优良、贮存稳定的单组分压敏胶。通过应用于压敏胶标签实例进一步验证了此压敏胶部分生产工艺及产品性能指标。     

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)。     

Evaluation of disposable diaper construction hot melt pressure‐sensitive adhesives using blends of olefinic block copolymer and amorphous polyolefin polymers—Adhesive performance,sprayability, and viscoelastic characteristics

Pressure‐sensitive adhesives (PSAs) used in disposable diaper construction have been formulated using blends of olefinic block copolymer (OBC) and an ethylene–propylene (PE‐PP) amorphous polyolefin (APO) polymer, with three different unsaturated hydrocarbon resins (with varying aromatic content), and also with two different saturated aliphatic hydrocarbon resin (with varying cycloaliphaticity). The viscoelastic properties of theses PSA formulations were studied using dynamic mechanical analysis (DMA). Viscosity profiles at five different temperatures were generated to better understand the application window for the resulting adhesive formulation. Rheology master curves were generated using time–temperature–superposition analysis and correlated with the processability characteristics. Adhesives used in disposable diaper construction were applied between a polyethylene backing and a nonwoven substrate with an air‐assisted spiral spray application technique on an Acumeter Spray Coater. After the adhesive was applied, peel adhesion testing on the samples was performed. It has been observed that the OBC/PE–PP‐based disposable diaper construction PSA has a lower application temperature along with wider tolerance for hydrocarbon resin chemistries, especially for the saturated aliphatic resin‐based PSA formulations. Based on the coating parameters used, it has been learned that the adhesive formulations seem to show a higher shear rate at the nozzle, but Reynolds number calculated indicated no major turbulence occurring at the nozzle during spraying. Very good spray patterns were obtained for the olefinic polymer‐based PSA formulations. Disposable diaper construction article showed good adhesive peel properties, especially for the adhesive formulations containing saturated aliphatic hydrocarbon resin, which were comparable to the SBS‐based control. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3311–3318, 2013     

乳液型丙烯酸酯压敏胶研究进展

针对乳液型丙烯酸酯PSA(压敏胶)的耐水性较差、耐高温性欠佳及涂布干燥速率较慢等弊病,综述了乳液型丙烯酸酯PSA的最新研究方向及进展(包括高固含量乳液型丙烯酸酯PSA、乳液型交联丙烯酸酯PSA、低表面能材料粘接用乳液型丙烯酸酯PSA和耐水性乳液型丙烯酸酯PSA等);最后对其应用前景进行了展望。     

Resultant synergism in the shear resistance of acrylic pressure‐sensitive adhesives prepared by emulsion polymerization of n‐butyl acrylate/2‐ethyl hexyl acrylate/acrylic acid

Acrylic emulsion pressure‐sensitive adhesives (PSAs) were synthesized by the copolymerization of n‐butyl acrylate with various levels of 2‐ethyl hexyl acrylate (2EHA) and a small constant amount of acrylic acid. The effect of varying the n‐butyl acrylate/2EHA monomer composition on the kinetic behavior of the polymerization and the characteristics of the copolymers prepared in a batch process were investigated. The results showed that increasing the amount of 2EHA in the monomer caused the polymerization rate and the glass‐transition temperature of the acrylic copolymers to decrease. Increasing the amount of 2EHA caused the gel content of the copolymers to decrease, reaching a minimum at 50 wt %; thereafter, the gel content increased at higher 2EHA levels. For the acrylic emulsion, the peel‐fracture energy of the PSAs decreased as the amount of 2EHA in the monomer was increased up to 50 wt %. At higher 2EHA levels, the peel‐fracture energy was relatively constant. Interestingly, a synergistic effect of increased shear resistance at 25 wt % 2EHA was observed without a significant trade‐off in terms of the peel and tack properties. This behavior was attributed to a good interconnection between the microgels and the free polymer chains inside the contacting particles in the adhesive film. Cooperation between various levels of 2EHA in the copolymer structure simultaneously changed the crosslink molecular weight (M_c) of the microgels and the entanglement molecular weight (M_e) of the free chains in the adhesive network morphology. The adhesive performance of the PSAs was found to be correlated with their M_c/M_e values as the 2EHA proportion was varied. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

反光膜用聚丙烯酸酯压敏胶的合成

以醋酸乙烯酯(VAc)为硬单体、丙烯酸异辛酯(EHA)和丙烯酸丁酯(BA)为软单体、丙烯酸(AA)和丙烯酸羟丙酯(HPA)为交联单体、过氧化苯甲酰(BPO)为引发剂和乙酸乙酯为溶剂,制备了反光膜用溶剂型聚丙烯酸酯PSA(压敏胶)。考察了各单体和引发剂含量对PSA性能的影响。结果表明:当w(VAc)=15%、m(EHA)∶m(BA)=3∶1、w(AA)=4%、w(HPA)=6%和w(BPO)=0.8%时,PSA的综合性能优异,并且完全满足反光膜的使用要求。     

Preparation and Properties of a Waterborne Contact Adhesive Based on Polychloroprene Latex and Styrene-Acrylate Emulsion Blend

Environmental protection and legislative pressure to eliminate the use of solvents in the adhesive industry have inspired the search for safer alternatives. In the area of contact adhesives, the waterborne route has proved to be of particular interest. Based on the synergistic effect of polychloroprene latex and styreneacrylate emulsion, a waterborne contact adhesive consisting of polychloroprene latex (PCL) and styreneacrylate emulsion (SAE) blend has been developed. In order to blend PCL with SAE easily and to accelerate the drying rate of the adhesive, boric acid was chosen for use in the PCL/SAE blend system. Effects of boric acid and SAE content on the properties of PCL/SAE blends, such as pH value, storage stability and set time, were investigated. At the same time, the effect of SAE content on the mechanical properties of PCL/SAE blend films was studied. The morphology of blend films was characterized by Atomic Force Microscopy. The adhesive performance of the waterborne contact adhesive was evaluated by peel and shear tests. The results showed that when the waterborne contact adhesive formulation contained 40 wt% styrene-acrylate emulsion (dry weight) and 1.25 wt% boric acid, it had a good shelf-stability, its set time was 5 min, and the blend film with this formulation was ductile and flexible with reasonably good tensile strength and very high elongation at break. And the blend films showed structure with a sea–island morphology. The waterborne contact adhesives derived from PCL/SAE blends were found to be comparable to the commercially available solvent-based contact adhesives. The synergistic effect of polychloroprene latex and styrene-acrylate copolymer emulsion was also discussed.     

微球型丙烯酸酯压敏胶的制备研究

采用悬浮聚合法制备了微球型丙烯酸压敏胶,以丙烯酸酯类单体为主体,在含有分散剂的水相中采用悬浮聚合的方法制备了粒径为10-100μm黏性聚合物微球.使用这种微球富集相按照一定比例调配自制的乳液,增稠剂及其他添加剂制得的压敏胶液用线棒涂布器涂布于纸等基材上烘干即得具有良好再剥离性的反复粘贴压敏胶.在吸取前人的经验并通过大量...     

Pressure Sensitive Adhesives Based on VectorR SIS Polymers I. Rheological Model and Adhesive Design Pathways

Dexco Polymers (a Dow/Exxon partnership) has been manufacturing Vector^R SIS polymers since 1990.¹ This paper describes experiments carried out to study Vector SIS polymers and model pressure sensitive adhesive (PSA) formulations based on Exxon Chemical's Escorez^R 1310LC tackifier. The adhesive behavior of tackified polymers was quantitatively analyzed by applying the rheological principle of time-temperature superposition² and the mapping approach,^3,4 and the pressure sensitive rheological model⁵ developed earlier. This model⁵ was developed by expanding and modifying an equation [adhesive fracture strength = (intrinsic adhesion) × (bulk energy dissipation)] proposed by Gent et al.^6,7 and Andrews et al.^8,9 This study delivers two key results. The first is that the fracture strength of the PSA/steel bond is the multiplication of three terms: the intrinsic (or interfacial) adhesion, the bonding and the debonding terms (Fig. 1). The debonding term is correlated with the logarithm of the loss modulus at the PSA debonding frequency or with the logarithm of the monomeric friction coefficient of the block copolymer/tackifier system. Both the loss modulus and the monomeric friction coefficient measure the energy dissipation in the bulk adhesive. The second is that PSA design pathways can be established by a mapping approach in the rheological space of the plateau modulus versus the loss modulus peak position in the frequency scale (Fig. 2). Plateau modulus is the bonding parameter because it measures the wetting capability of the adhesive with the substrate surface. The loss modulus peak position is the debonding parameter because it corresponds approximately to the time scale (or the frequency scale) in which one deforms the adhesive to maximize energy dissipation. Therefore, the tackifier and oil combination lowers the plateau modulus, but increases the T_g of the polyisoprene phase of the SIS polymer. This increase in T_g is equivalent to the lowering of the rate of local rearrangement (frequency of segment jumps) of the polyisoprene chains of the block copolymer. An optimal “tackification pathway” in this rheological space is achieved by tailoring the tackifier type and T_g, and the amount of oil used in the PSA.

In brief, the PSA rheological model and mapping approach described in this work for Vector SIS polymers give a comprehensive understanding and adhesive design pathways. This concept and approach not only allow raw material suppliers to improve and design better tackifier and polymer products, but also provide PSA formulators a quantitative tool to achieve PSA end property results.     

Fundamental Understanding in Rolling Ball Tack of Tackified Block Copolymer Adhesives

In the pressure sensitive adhesive (PSA) industry, rolling ball tack is a very common tack test, which is simple, inexpensive and easy to operate. This work attempts to search for key parameter(s), which will affect the rolling ball tack of a PSA based on a blend of styrene-isoprene-styrene triblock copolymer(SIS) and hydrocarbon tackifier(s). We want to better understand whether this particular PSA performance is controlled by the surface or bulk properties of the adhesive.

Firstly, to test the contribution from the surface properties, we employ a model system of SIS/aliphatic tackifier in 1/1 wt. ratio as the control. Part of the tackifier in this PSA is then replaced by various amounts of low molecular weight diluents with different surface tensions. The idea is to vary the surface properties of the PSA because these low surface tension and low molecular weight diluents tend to migrate to the PSA surface. It is observed that the incorporation of a lower surface tension and a lower molecular weight diluent in the PSA tends to produce a larger increase in rolling ball tack compared with the unmodified PSA. On the other hand, the incorporation of a higher surface tension and a more compatible diluent tends to produce a larger increase in loop, peel and quick stick. Each diluent lowers the shear adhesion failure temperature (SAFT) of the diluent-modified PSA. These observations are explained in terms of tackifier molecular weight, and surface tension and compatibility of the various components (polyisoprene, tackifier, diluent and oil) in the adhesive formulation.

Secondly, to test the contribution from the bulk properties, we derive an equation for rolling ball tack in terms of the bulk viscoelastic behavior of the block copolymer PSA. However, experimental values of rolling ball tack do not follow this equation. Also, with increasing tackifier concentration in SIS, rolling ball tack has very different behavior compared with loop, peel, quick stick and probe tack. The latter set of performance criteria is known to be related to PSA bulk viscoelastic behavior. Therefore, these suggest that rolling ball tack is related more to the surface properties than to the bulk properties of the adhesive based on these results and those of the diluent-modified PSA systems.     

Fundamental Understanding in Rolling Ball Tack of Tackified Block Copolymer Adhesives

In the pressure sensitive adhesive (PSA) industry, rolling ball tack is a very common tack test, which is simple, inexpensive and easy to operate. This work attempts to search for key parameter(s), which will affect the rolling ball tack of a PSA based on a blend of styrene-isoprene-styrene triblock copolymer(SIS) and hydrocarbon tackifier(s). We want to better understand whether this particular PSA performance is controlled by the surface or bulk properties of the adhesive.

Firstly, to test the contribution from the surface properties, we employ a model system of SIS/aliphatic tackifier in 1/1 wt. ratio as the control. Part of the tackifier in this PSA is then replaced by various amounts of low molecular weight diluents with different surface tensions. The idea is to vary the surface properties of the PSA because these low surface tension and low molecular weight diluents tend to migrate to the PSA surface. It is observed that the incorporation of a lower surface tension and a lower molecular weight diluent in the PSA tends to produce a larger increase in rolling ball tack compared with the unmodified PSA. On the other hand, the incorporation of a higher surface tension and a more compatible diluent tends to produce a larger increase in loop, peel and quick stick. Each diluent lowers the shear adhesion failure temperature (SAFT) of the diluent-modified PSA. These observations are explained in terms of tackifier molecular weight, and surface tension and compatibility of the various components (polyisoprene, tackifier, diluent and oil) in the adhesive formulation.

Secondly, to test the contribution from the bulk properties, we derive an equation for rolling ball tack in terms of the bulk viscoelastic behavior of the block copolymer PSA. However, experimental values of rolling ball tack do not follow this equation. Also, with increasing tackifier concentration in SIS, rolling ball tack has very different behavior compared with loop, peel, quick stick and probe tack. The latter set of performance criteria is known to be related to PSA bulk viscoelastic behavior. Therefore, these suggest that rolling ball tack is related more to the surface properties than to the bulk properties of the adhesive based on these results and those of the diluent-modified PSA systems.     

溶剂型聚丙烯酸酯压敏胶合成工艺的研究

以丙烯酸丁酯(BA)为软单体、丙烯酸甲酯(MA)为硬单体、2-丁酮(MEK)为溶剂和偶氮二异丁腈(AIBN)为引发剂,采用溶液聚合法合成了溶剂型聚丙烯酸酯类压敏胶(PSA)。考查了聚合反应温度、引发剂用量、软硬单体质量比和烘胶温度等因素对PSA性能的影响。结果表明:当聚合反应温度为80℃、w(AIBN)=0.4%(相对于总单体质量而言)、m(BA):m(MA)=2.5:1和烘胶温度为70℃时,PSA的综合性能相对较好。     

聚丙烯酸酯涂料印花黏合剂的合成与性能研究

以过硫酸铵(APS)为引发剂、甲基丙烯酸甲酯(MMA)为硬单体、丙烯酸丁酯(BA)和丙烯酸异辛酯(EHA)为软单体、丙烯酸(AA)为功能单体和N-羟甲基丙烯酰胺(NMA)为交联单体,采用预乳化法合成出一种聚丙烯酸酯涂料印花黏合剂。讨论了单体滴加方式、预乳化液滴加时间、阴/非离子型乳化剂配比及用量、交联剂和各单体用量等对该黏合剂乳液性能的影响。结果表明:当w(BA)=15%、w(EHA)=8%、w(MMA)=20%、w(NMA)=3.0%、滴加时间为2.5 h、复合乳化剂中m(SDS):m(OP-10)=1:2且w(复合乳化剂)=6%时,该黏合剂乳液具有优良的综合性能,能够满足织物印花的使用要求。     

溶剂型丙烯酸酯压敏胶基质对贴片黏附性的影响

考察了不同的丙烯酸酯压敏胶(PSA)型号、溶剂系统组成及含量、高分子添加剂类型及含量等对PSA基质黏附性的影响。通过测定180°剥离强度和持粘力探讨了干燥条件对基质黏附性的影响,并对各因素进行优化筛选。结果表明:Duro-Tak87-2677的180°剥离强度为0.88kN/m,持粘力为50h,适合作为丙烯酸酯PSA的基质;当组合溶剂中V(异丙醇)∶V(正庚烷)∶V(乙酸乙酯)=37∶37∶21、m(水)∶m(乙醇)∶m(组合溶剂)=10∶7∶(67～70)时,PSA基质的溶剂系统为均一体系;当w(RLPO)=5%、干燥温度为80℃和干燥时间为15min时,丙烯酸酯PSA基质的180°剥离强度为0.1～0.6kN/m,持粘力9h,黏附性较好。     

A molecular simulation analysis of influence of lignosulphonate addition on properties of modified 2-ethyl hexyl acrylate/methyl methacrylate/acrylic acid based pressure sensitive adhesive

A novel PSA formulation that incorporates a bio-sourced lignosulphonate has been proposed. A molecular dynamics simulation study is attempted to explore the effect of lignosulphonate addition on the adhesion, thermal and mechanical properties of a conventionally used acrylic PSA composed of 2-EHA, MMA and AA. A good agreement of conventional PSA density and glass transition temperature, T_g, with literature estimates confirmed the accuracy of the molecular simulations. It is observed that there is an increase in PSA-substrate interaction energy with an increase in lignosulphonate content despite an increase in T_g due to its addition. This is proposed to be primarily due to an increase in polar groups contributed by lignosulphonate. The availability of more polar groups in bulk and increased density of these groups due to significant migration to interface results in an increase in interfacial energy, and hence, improved PSA adhesion. The shear modulus is observed to increase with increase in lignosulphonate content indicating its effectiveness to resist PSA shear deformation. Simulations suggest that in order to form an industrially useful adhesive, that may work well under RT conditions possessing an optimum cohesive strength and surface adhesion, a PSA formulation with ~15 wt.% lignosulphonate may be used.     

聚丙烯酸酯压敏胶的研制及在反光膜中的应用

以丙烯酸异辛酯(EHA)和丙烯酸丁酯(BA)为软单体,甲基丙烯酸甲酯(MMA)为硬单体,丙烯酸(AA)和丙烯酸羟丙酯(HPA)为交联单体,过氧化苯甲酰(BPO)为引发剂,乙酸乙酯为溶剂,采用溶液聚合法制备了一种溶剂型聚丙烯酸酯压敏胶。考查了各单体用量对压敏胶综合性能的影响。结果表明,当软单体质量分数为85%、MMA质量分数为5%、AA质量分数为6%和HPA质量分数为4%时,PSA综合性能优异,可满足反光膜的使用要求。     

葡萄糖基可聚合乳化剂的合成及其在乳液压敏胶中的应用

丙烯酸酯乳液压敏胶是一类应用广泛的低VOC含量环保胶黏剂。本文合成了一种葡萄糖基可聚合乳化剂-丁基葡萄糖苷马来酸酯（BGMAH）,并采用半连续种子乳液聚合工艺制备了BGMAH改性的丙烯酸酯乳液压敏胶。通过系统考察BGMAH的结构及用量等因素对乳液粒径、乳胶膜耐水性和粘接性能的影响发现,当复合乳化剂质量分数保持3%不变,m(BGMAH):m(OP-10):m(SDS)=2:1.5:0.5时,乳胶膜的粘接性能和耐水性能最佳。红外、热稳定性等分析表明丙烯酸酯乳液在改性过程当中发生了共聚交联反应,且改性后聚合物体系相容性良好,乳胶膜的玻璃化转变温度和热稳定性均提高,同时对聚合体系的反应机理也进行了研究。