Photoreactive UV-crosslinkable acrylic pressure-sensitive adhesives containing type-II photoinitiators

UV-crosslinking is an established technology used in many industrial manufacturing processes. New applications and technical specifications of UV technologies stimulate the continuous development of photoinitiators that can efficiently meet specific requirements. A typical class of radical-reactive type-II photoinitiators has been used for the UV-initiated crosslinking of acrylic pressure-sensitive adhesives (PSAs).The activity of type-II photoinitiators such as: benzophenone derivatives, thioxanthone derivative, antraquinone derivative and fluorenone (without tertiary amine as a co-initiator) in the photoreactive UV-crosslinkable acrylic pressure-sensitive adhesives was described. The effect of the type-II photoinitiators on the acrylic PSA properties (tack, peel, and shear strength) was summarized.     

Study on affecting factors of curing rate in ultraviolet curing adhesives containing modified acrylic ester prepolymers

Abstract

Ultraviolet (UV) curing adhesives have been extensively utilized in fields of health care and electronic components due to low energy consumption and solvent pollution. The most used system is modified acrylic ester system whose merits are low cost, high reliability and tensile strength. However, higher UV curing rate is still pursued especially in field of quick dry adhesives as well as influencing factors of curing rate are very complex. For clarifying affecting factors of curing rate as well as achieving higher curing rate, in this work, several UV curing adhesives with acrylic photosensitive resin prepolymers modified by epoxy and polyurethane were prepared. The impacts of class and content of radical photo-initiators, prepolymers and reactive diluents on UV curing rate were deeply researched. Moreover, the influence of oxygen polymerization inhibition on curing rate was discussed as well. The significantly elevated curing rates were obtained in as-prepared adhesives, in comparison with commercial ones. This work might offer a facile and effective strategy to obtain the promising high-performance modified acrylic ester prepolymer bearing UV curing adhesives with a significantly elevated high curing rate by well controlling these investigated affecting factors.     

Photoreactive UV-crosslinkable solvent-free acrylic pressure-sensitive adhesives containing copolymerizable photoinitiators based on benzophenones

The design and development of new, tailor-made, novel photoreactive acrylic pressure-sensitive adhesives, which can cope with both the technical and ecological demands, is therefore a continuing challenge for industrial research and development. Progress in the coating technology and the development of improved photoreactive acrylic adhesive will open the door for new applications and an extended market penetration of UV-crosslinkable acrylic adhesive raw materials containing unsaturated copolymerizable photoinitiators incorporated into the polymer backbone. They are characterized by good tack, good adhesion, excellent cohesion and very high shrinkage resistance. In this paper it is shown the application of H-abstractor such as 4-acryloyloxy benzophenone to obtain of the UV-crosslinked acrylic PSA.The presented novel UV-crosslinkable acrylic hotmelt PSA combines the economic advantages of the hotmelt coating technology with the high performance characteristics of the acrylic chemistry, including an excellent aging resistance, optical transparency and heat resistance.     

Poly(acrylate/epoxy) hybrid adhesives for low‐surface‐energy plastic adhesion

The formulation, polymerization, and performance of a new class of low‐surface‐energy adhesives for plastics are described. The polymerization involves the simultaneous room‐temperature polymerization of polyoxirane monomers in an acrylic monomer phase. The polymerization of the acrylic phase and adhesion promotion to plastics are catalyzed after the decomplexation and oxidation of trialkylborane–amine complexes. The polymerization of the epoxy phase is catalyzed with a Lewis acid such as BF₃, ZnCl₂, or SnCl₄ complexed with ether or amine. This article explores the resulting adhesives as a function of the epoxy monomer functionality, concentration, solubility in the acrylic monomer, Lewis acid catalyst concentration, phase crosslinking, and postprocessing thermal history. The adhesive morphology exhibits a finely dispersed epoxy phase strongly interacting with the major acrylic phase resulting from a nucleation‐and‐growth phase‐separation mechanism. Excellent adhesion to plastics, including polyethylene, polypropylene, poly(tetrafluoroethylene), poly(ethylene terephthalate), and nylon, is achieved with a much higher thermal performance than that achievable with acrylic polymers alone. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 989–998, 2007     

Radiation curable polyesters for the formulation of pressure sensitive adhesives

A special type of polyesters for pressure sensitive adhesives have been developed. The structure of copolymer is of saturated main chain with acrylic double bonds at the end. Those results are introduced. In addition to that, a few aspects connected to practical use of those materials are mentioned.     

Contact adhesives based on polyurethanes and natural rubbers

A review of the chemistry, technology, properties, and range of application of contact polyurethane adhesives, as well as adhesives based on natural rubber, is presented. The main types of adhesives produced by the Anles corporation are described.     

Visible-Light-Curable Solvent-Free Acrylic Pressure-Sensitive Adhesives via Photoredox-Mediated Radical Polymerization

Owing to their excellent properties, such as transparency, resistance to oxidation, and high adhesivity, acrylic pressure-sensitive adhesives (PSAs) are widely used. Recently, solvent-free acrylic PSAs, which are typically prepared via photopolymerization, have attracted increasing attention because of the current strict environmental regulations. UV light is commonly used as an excitation source for photopolymerization, whereas visible light, which is safer for humans, is rarely utilized. In this study, we prepared solvent-free acrylic PSAs via visible light-driven photoredox-mediated radical polymerization. Three α-haloesters were used as additives to overcome critical shortcomings, such as the previously reported low film curing rate and poor transparency observed during additive-free photocatalytic polymerization. The film curing rate was greatly increased in the presence of α-haloesters, which lowered the photocatalyst loadings and, hence, improved the film transparency. These results confirmed that our method could be widely used to prepare general-purpose solvent-free PSAs—in particular, optically clear adhesives for electronics.     

Adhesion and thermal properties of acrylic anaerobic adhesives modified with maleimides

The possibility of enhancing the heat resistance of acrylic anaerobic adhesives by introducing maleic acid imides was examined. The influence of the structure of the maleimides on the heat resistance of the compounds was studied. It was demonstrated by the example of the maleimide-diethylene glycol monomethyl ether methacrylate pair that imides are capable of copolymerization with acrylic monomers under the conditions of anaerobic curing at 25°C.     

The crosslinking reaction of acrylic PSA using chelate metal acetylacetonates

In this work, metal chelate zirconium acetylacetonate (ZrACA) was added into acrylic polymers with self-adhesive properties. These acrylic polymers, known as acrylic pressure-sensitive adhesives (PSA), were crosslinked with ZrACA to obtain acrylic self-adhesives with which to study the crosslinking reaction between carboxylic groups of the polymer chain and metal chelate crosslinking agent.     

Investigations of protein casein adhesives in 1927–1934 in research works of Central Aerohydrodynamic Institute and All-Russia Institute of the Aircraft Materials

An initial study of the adhesives in the Soviet Union aimed at the application of adhesives in air-craft engineering is presented. A general concept of the adhesives in 1920 is given, the assortment of the zoogenic protein adhesives is presented, and the manufacturing procedure of the latter is outlined. Detailed information on the results of the first scientific-research works in the country in the field of the adhesives carried out at the Department of the Research of the Aircraft Materials of the Central Aerohydrodynamic Institute (TsAGI) is presented. It has been found that the fundamental study of the adhesives in our country arose due to the development of domestic wooden aviation and the manufacturing of airplanes from wood.     

Investigations of zoogenic protein adhesives used for domestic aircraft engineering prior to 1930

An initial study of the adhesives in the Soviet Union aimed at the application of adhesives in air-craft engineering is presented. A general concept of the adhesives in 1920 is given, the assortment of the zoogenic protein adhesives is presented, and the manufacturing procedure of the latter is outlined. Detailed information on the results of the first scientific-research works in the country in the field of the adhesives carried out at the Department of the Research of the Aircraft Materials of the Central Aerohydrodynamic Institute (TsAGI) is presented. It has been found that the fundamental study of the adhesives in our country arose due to the development of domestic wooden aviation and the manufacturing of airplanes from wood.     

Heat- and high-temperature-resistant adhesives for joining carbon and ceramic materials

A review of the literature datas on the application of adhesives based on inorganic binders for joining carbon and ceramic materials was presented and their advantages and disadvantages were revealed. It was concluded that the most preferable for many application fields are polymer carbonizing adhesives with special fillers, and the most promising are the cold-setting adhesives. Datas are presented on the development of new modified ZhTK-14D adhesive compositions that are efficient at temperatures up to 1800°C intended for joining carbon and ceramic materials.     

Development of solvent-free acrylic pressure-sensitive adhesives

The present publication describes a problem to develop solvent-free acrylic pressure-sensitive adhesives (PSA). Solvent-free PSA are established materials for the manufacturing of various self-adhesive products. Only by means of these acrylic PSA was it possible to succeed in drafting the present surprisingly efficient generation of double-sided pressure-sensitive adhesive tapes, medical products, protective masking films, films for the graphics market, and various specialty products. New applications and technical specifications stimulate the continuous development of new methods of polymerization of solvent-free acrylates. New syntheses of solvent-free acrylic PSA include polymerization in the reactor with removal of the solvent and polymerization on the carrier. The polymerization process is connected with UV-crosslinking.     

阻燃聚丙烯酸酯胶的合成

通过溶液聚合法制得了阻燃性丙烯酸酯胶。研究了甲基丙烯酸2,4,6-三溴苯酯及引发剂用量,交联单体及反应温度、反应时间等对剥离强度的影响。研究了多元共聚丙烯酸酯胶的单体组成、合成工艺及其产品性能。结果表明,制得的胶粘剂在室温下剥离强度为19．5N／cm。     

Robust and recoverable dual cross-linking networks in pressure-sensitive adhesives

Pressure-sensitive adhesives (PSAs) demand the ability to simultaneously improve toughness and adhesion. However, these requirements of PSAs have remained a great challenge because robust and recoverable characteristics are usually contradictory properties of PSAs. Dual cross-linking networks developed by incorporating dynamic noncovalent bonds into chemical cross-linking networks have the potential to mitigate these requirements in a wide variety of applications including adhesives, hydrogels, and elastomers. Herein, a facile approach to achieve dual cross-linking networks of acrylic PSAs with excellent mechanical properties and high-adhesive performance that integrate physically cross-linked networks into chemically cross-linked networks is proposed. Diurethane acrylic monomer-pentaerythritol ethoxylate (DAM-PEEL) groups were introduced into the acrylic PSA system through photopolymerization. The PSA/DAM-PEEL dual cross-linking networks led to the development of the chemically cross-linked networks for both PSA and DAM via covalent bonds and the physically cross-linked networks between the amide groups of DAM and the hydroxyl groups of PEEL via hydrogen bonds. Consequently, the PSA/DAM-PEEL dual cross-linking networks were able to simultaneously improve the modulus and stretchability. This design strategy for developing dual cross-linking networks of materials could offer potential applications for various adhesive-related applications.     

Application of adhesives in instrument engineering

A variety of adhesives produced at the enterprise, including optical, melt, and current-conducting adhesives, is presented. The technical characteristics of these glues and their function in the process of manufacturing quantum electronics instruments are discussed.     

Development in the area of UV-crosslinkable solvent-based pressure-sensitive adhesives with excellent shrinkage resistance

Solvent-based UV-crosslinkable pressure-sensitive adhesives (PSA) present a new class of products that offers the potential to produce a novel generation of ultraviolet cured self-adhesive products with excellent shrinkage resistance. A variety of solvent-based pressure-sensitive adhesives were prepared by synthesis in ethyl acetate with solid content on 50 wt.% with 2-ethylhexyl acrylate, methyl acrylate, acrylic acid, N-vinyl caprolactam and unsaturated photoinitiators: 4-acryloyloxy benzophenone, allyl benzoine and phenyl-(1-acryloyloxy)-cyclohexyl ketone. The main emphasis is given to the influence of viscosity and molecular mass of synthesized adhesive on their shrinkage. Further trials show the effect of the UV-crosslinking process with UV-lamp and comparison with acrylics PSA crosslinked with metal chelates aluminium acetylacetonate and titanium acetylacetonate on shrinkage. Further examinations describe the influence of various factors such as UV exposure time and UV dose on very relevant PSA performance such as shrinkage on coated PVC carrier.     

Aqueous adhesives

A review of aqueous adhesives manufactured by domestic industry and ways of elimination of joints defects formed by these adhesives are presented.     

New developments in the field of reactive acrylic adhesives and sealing materials

The influence of oligomeric base on the properties of acrylic adhesives and sealants cured by radical mechanism is studied. New anaerobic materials on the basis of oligourethane(meth)acrylates (OUMs) are developed. It is shown that, by adjusting the OUM nature, it is possible to increase the heat and moisture stability of adhesive compositions. As a result of these works, UV-cured adhesive compositions, heat-cured adhesive for bonding untreated aluminum, and two-part adhesive compounds cured at both positive and negative temperatures are developed.