Laromer 9023

The following components were used to prepare epoxy acrylic resins (EARs) via the bulk photopolymerization process:(I)

base monomers: n-butyl acrylate (BA), glycidyl methacrylate (GMA), 2-hydroxyethyl acrylate (HEA) (Merck Group, Warsaw, Poland);

(II)

methacrylic monomers: methyl methacrylate (MMA), ethyl methacrylate (EMA), butyl methacrylate (BMA), lauryl methacrylate (LMA), (2-acetoacetoxy)ethyl methacrylate (AEM) (Merck Group, Warsaw, Poland)

(III)

vinyl monomers: N-vinylpyrrolidone (NVP) (BASF, Ludwigshafen, Germany) and styrene (STY) (Merck Group, Warsaw, Poland),

The chemical structures of the comonomers are shown in Table 1. As a radical photoinitiator, an acylphosphine oxide type photoinitiator was used, i.e., 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide (Omnirad TPO, IGM Resins, Waalwijk, The Netherlands).
Epoxy-acrylate structural adhesive tapes (SATs) were compounded using EARs and the Bisphenol A-based liquid epoxy resin with an epoxy equivalent weight of 202 g/equiv. and viscosity of 25 Pa∙s (Epidian; Ciech Sarzyna, Nowa Sarzyna, Poland), radical photoinitiator Omnirad 127 (IGM Resin, The Netherlands), the multifunctional acrylic monomer (Laromer 9023; BASF, Ludwigshafen, Germany), the Lewis acid adduct (as a latent curing agent) (Nacure Super Catalyst A218; Worleé Chemie, Hamburg, Germany), and an adhesion promoter (Byk 4510 (Byk-Chemie, Wesel, Germany).

The following components were used for the preparation of the acrylic syrups (ASs): n-butyl acrylate (BA), butyl methacrylate (BMA), 2-hydroxyethyl acrylate (HEA) (BASF, Ludwigshafen, Germany), and glycidyl methacrylate (GMA) (Dow Europe, Horgen, Germany). Acylphosphine oxides, i.e., bis(2,4,6-trimethylbenzoyl)-phenyl phosphine oxide (Omnirad 819, IGM Resins, Waalkwijk, The Netherlands), and 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide (Omnirad TPO; IGM Resins, Waalkwijk, The Netherlands) were used as type I radical photoinitiators. Thermally curable double-sided SATs were compounded using ASs, the Bisphenol A-based liquid epoxy resin with an epoxy equivalent weight of 202 g/equiv. and viscosity of 25 Pa∙s (Epidian; Ciech Sarzyna, Nowa Sarzyna, Poland), the Omnirad 127 photoinitiator (IGM Resins, Waalwijk, The Netherlands), 1,6-hexanediol diacrylate (Laromer HDDA, BASF, Ludwigshafen, Germany), the epoxy-modified acrylic resin (Laromer 9023; BASF, Ludwigshafen, Germany), the Lewis acid adduct (as a latent curing agent) (Nacure Super Catalyst A218; Worleé Chemie, Hamburg, Germany), Byk 4510 as an adhesion promoter, and Byk 378 as a surface additive (Byk-Chemie, Wesel, Germany).

The following components were used for the preparation of epoxyacrylate copolymers (EAC): n-butyl acrylate (BA); glycidyl methacrylate (GMA); 4-hydroxybutyl acrylate (HBA) (BASF, Ludwigshafen, Germany); 4-acryloyloxy benzophenone (ABP, Chemitec, Scandiccy, Italy); 2,2-azobis(isobutyronitryle) (AIBN, Merc, Darmstadt, Germany); and ethyl acetate (POCh, Gliwice, Poland) as a solvent. The commercial benzoxazine resins Araldite MT 35910 and Araldite MT 35700 (Huntsman, Everberg, Belgium), latent curing agents (IL-0003-HP, Ionic Liquids Technologies GmbH, Heilibronn, Germany; and Nacure Super A233, Worleé Chemie, Hamburg, Germany), a multifunctional monomer (Laromer 9023, BASF, Germany), a radical photoinitiator (Omirad 127, IGM Resins, Waalwijk, The Netherlands), and a surface-tension-reducing compound to improve wettability of the substrates (Byk 325, Byk-Chemie, Wesel, Germany) were used as components of the self-adhesive structural tapes (SATs). The chemical structures and characteristics of benzoxazine resins (BRs) and latent curing agents (LCAs) are showed in Table 1 and Figure 1, respectively.