specialty methacrylates for better adhesive strength and resistance

Increased adhesive strength and resistance

ADHESIVES AND SEALANTS

Methacrylate-based reactive acrylics are used in adhesive and sealant formulations with applications in various industries. Anaerobic or structural adhesives are commonly used in automotive, aerospace, and construction, while emulsion polymers for pressure-sensitive adhesives and sealants contain VISIOMER® specialty methacrylates used in packaging, labeling, and medical devices.

Structural Adhesives

Structural methacrylic adhesives and sealants are commonly used in the transportation and marine industries for OEM assembly. The choice of monomers for these adhesives depends on the substrate being bonded, and they are advantageous because they usually do not require surface preparation. VISIOMER® HEMATMDI, a crosslinking monomer, can enhance adhesion to polar surfaces, and crosslinkers are necessary for ensuring cohesion strength. 

The selection of methacrylate monomers is crucial, and formulators must balance their physical properties to achieve the desired strength and flexibility in their applications. Monomers such as VISIOMER® BNMA or VISIOMER® c-HMA may be chosen for their dimensional stability or high heat resistance. Reactivity must be balanced to provide a rapid cure without damaging the part. VISIOMER® HEMA-P can improve adhesion and corrosion resistance, while VISIOMER® MEEU 25 M and VISIOMER® MEEU 50 W are preferred for its ability to adhere to oily metals and soften polymer matrixes. 

Evonik offers a range of di- or trifunctional crosslinking monomers for structural adhesive applications, with VISIOMER® TMPTMA being recommended for high crosslinking densities. Difunctional crosslinkers like VISIOMER® EGDMA, VISIOMER® TRGDMA, and VISIOMER® 1,4 BDDMA vary in chain length and can affect final mechanical properties.

Long-chain alkyl methacrylates are suitable for non-polar surface materials, while VISIOMER® IDMA or VISIOMER® Terra C13-MA can enhance adhesion to low-energy surfaces. VISIOMER® THFMA or VISIOMER® Terra IBOMA can improve the mechanical performance of methacrylate adhesives, and replacing methyl methacrylate (MMA) with VISIOMER® THFMA can enhance elongation properties while maintaining comparable Young's moduli in adhesive formulations.

ANAEROBIC ADHESIVES

As their name implies, anaerobic adhesives cure in the absence of oxygen. They are one-component systems that polymerize under the influences of organic hydroperoxides in the presence of metal ions. Owing to the necessary presence of metal ions, anaerobic adhesives and sealants are practically only suitable for bonding and sealing metals. Main application areas are screw locking, fixing, joining, bonding and sealing of pipes and flanges. 

Polyethylene glycol dimethacrylates, and especially VISIOMER® TRGDMA and VISIOMER®PEG 200 DMA, are the most important group of monomers for manufacturing anaerobic adhesives. 

Pressure sensitive adhesives

Methacrylate monomers are used as comonomers mainly in binders for water-based PSAs, but also for acrylic hot melt systems. They are added to improve mechanical properties and provide additional functionalities like adhesion promotion.  VISIOMER® MEEU 25 M and VISIOMER® MEEU 50 W are used to improve adhesion and cohesion of emulsion polymers for PSA's. Acrylic PSAs are mainly used as adhesives for labels, tapes or lamination, especially in the packaging industry.

Metal impregnation

Sintered- or cast metal materials contain faults in the form of crazes or pores, which often require sealing. For this purpose, formulations based on mixtures of mono- and multifunctional (meth)acrylates are used. Long-chain aliphatic acrylates and methacrylates or hydroxyfunctional methacrylates are employed for the monofunctional component, whereas VISIOMER® PEG 200 DMA, VISIOMER® TMPTMA and VISIOMER® 1,4-BDDMA are preferred for the multifunctional component. The impregnation resin containing polymerization initiator is introduced into the metal pores by vacuum or pressure and cured by heat. 

Benefits of specialty methacrylates for adhesives and sealants

  • Enhanced cohesive strength and resistance
  • Fomulation components with low hazard potential
  • Increased adhesion to polar substrates
Evonik adhesives and sealants industry team

Industry team adhesives and sealants 

The adhesives and sealants industry team consists of experts from the Coating & Adhesive Resins, Silica, Silanes, Interface & Performance, Methacrylates, Crosslinkers, Performance Intermediates and High Performance Polymers Business Lines. In doing so, we bundle the competencies for the adhesives and sealants industry. 

Selected Solutions for adhesives and sealants

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