Di-Hydroxylated Soybean Oil Polyols with Varied Hydroxyl Values and Their Influence on UV-Curable Pressure-Sensitive Adhesives

Preparation and structural characterization of epoxidized soybean oils-based pressure sensitive adhesive grafted with tea polyphenol palmitate

Vegetable oils-based pressure sensitive adhesives (PSAs) are green and sustainable but face unsatisfactory adhesion strengths and are prone to aging during storage and application due to the existence of residual double bonds and massive ester bonds. Nine common antioxidants (tea polyphenol palmitate (TPP), caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, and tea polyphenols) were grafted into epoxidized soybean oils-PSA (ESO-PSA) system to enhance antiaging properties and adhesion strengths. Results showed ESO-PSAs grafted with caffeic acid, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate, tea polyphenols, or TPP didn't occur failure with TPP having best performance. The optimal conditions were ESO reacted with 0.9 % TPP, 70 % rosin ester, and 7.0 % phosphoric acid at 50 °C for 5 min, under which peel strength and loop tack increased to 2.460 N/cm and 1.66 N, respectively, but peel strength residue reduced to 138.09 %, compared with control (0.407 N/cm, 0.43 N, and 1669.99 %). Differential scanning calorimetry and thermogravimetric results showed TPP grafting increased the glass transition temperature of ESO-PSA slightly but improved its thermal stability significantly. Fourier transform infrared spectroscopy and 1H nuclear magnetic resonance results showed TPP, phosphoric acid, and rosin ester all partially participated in the covalently crosslinking polymerization of ESO-PSAs and the rest existed in the network structures in the free form.

Epoxidized Soybean-Oils-Based Pressure-Sensitive Adhesives with Di-Hydroxylated Soybean-Oils Copolymerizing and Antioxidant Grafting

Vegetable-oils-based pressure-sensitive adhesives (PSAs) are being developed as a substitute for petrochemical-based PSAs for application in daily life. However, vegetable-oils-based PSAs face the problems of unsatisfactory binding strengths and easy aging. In this work, the grafting of antioxidants (tea polyphenol palmitates, caffeic acid, ferulic acid, gallic acid, butylated hydroxytoluene, tertiary butylhydroquinone, butylated hydroxyanisole, propyl gallate (PG), tea polyphenols) was introduced into an epoxidized soybean oils (ESO)/di-hydroxylated soybean oils (DSO)-based PSA system to improve the binding strengths and aging-resistant properties. PG was screened out as the most suitable antioxidant in the ESO/DSO-based PSA system. Under optimal conditions (ESO/DSO mass ratio of 9/3, 0.8% PG, 55% rosin ester (RE), 8% phosphoric acid (PA), 50 °C, and 5 min), the peel adhesion, tack, and shear adhesion of the PG-grafted ESO/DSO-based PSA increased to 1.718 N/cm, 4.62 N, and >99 h, respectively, in comparison with the control (0.879 N/cm, 3.59 N, and 13.88 h), while peel adhesion residue reduced to 12.16% in comparison with the control (484.07%). The thermal stability of the ESO/DSO-based PSA was enhanced after PG grafting. PG, RE, PA, and DSO were partially crosslinked in the PSA system, with the rest being free in the network structures. Thus, antioxidant grafting is a feasible method for improving the binding strengths and aging-resistant properties of vegetable-oils-based PSAs.

Preparation and Properties of Plant-Oil-Based Epoxy Acrylate-Like Resins for UV-Curable Coatings

Novel oil-based epoxy acrylate (EA)-like prepolymers were synthesized via the ring-opening reaction of epoxidized plant oils with a new unsaturated carboxyl acid precursor (MAAMA) synthesized by reacting maleic anhydride (MA) with methallyl alcohol (MAA). Since the employed epoxidized oils including epoxidized soybean oil (ESO), epoxidized rubber seed oil (ERSO), and epoxidized wilsoniana seed oil (EWSO) possessed epoxy values of 7.34–4.38%, the obtained epoxy acrylate (EA)-like prepolymers (MMESO, MMERSO, and MMEWSO) indicated a C=C functionality of 7.81–4.40 per triglyceride. Furthermore, effects of the C=C functionality and the addition of hydroxyethyl methacrylate (HEMA) diluent on the ultimate properties of the resulting UV-cured EA-like materials were investigated and compared with those of commercially available acrylated ESO (AESO) resins. As the C=C functionality increased, the storage modulus at 25 °C (E’₂₅), glass transition temperature (T_g), 5% weight–loss temperature (T₅), tensile strength and modulus (σ and E), and hardness of the coating for both the pure EA and EA/HEMA resins increased significantly as well. These properties indicated similar trends when comparing the EA materials with 30% of HEMA with those pure EA materials. Specially, although ERSO had a clearly lower epoxy value that ESO, both the UV-cured pure MMERSO and MMERSO/HEMA materials showed much better E’₂₅, T_g, σ, and E than their AESO counterparts, indicating that the MAAMA modification of epoxidized plant oils was much more effective than the modification of acrylic acid to achieve high-performance oil-based epoxy acrylate resins.

Copolymers from epoxidized soybean oil and lactic acid oligomers for pressure-sensitive adhesives

Corn based lactic acid oligomers and soybean based epoxidized oil were copolymerized under UV irradiation for biobased pressure-sensitive adhesives (PSA).

Synthesis and characterization of acrylic polyols and polymers from soybean oils for pressure-sensitive adhesives

Soybean oil based acrylic polyol with modulated acrylate and hydroxyl functionalities was polymerized under UV radiation for biobased pressure-sensitive adhesives (PSA).