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Preparation and Characterization of Water-Soluble Acrylic Pressure Sensitive Adhesive

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Preparation and Characterization of Water-Soluble Acrylic Pressure Sensitive Adhesive Open Access Journal of Waste Management & Xenobiotics ISSN: 2640-2718 Preparation and Characterization of Water-soluble Acrylic Pressure Sensitive Adhesive Juhyeon L1 and Jaehee L2* Research Article 1Hankuk Academy of Foreign Studies, Korea Volume 1 Issue 2 Received Date: November 01, 2018 2Gaia Corporation, Korea Published Date: November 15, 2018 *Corresponding author: Jaehee Lee, Hankuk Academy of Foreign Studies, 32-36 DOI: 10.23880/oajwx-16000110 Yuseongdaero, 1596beon-gil, Yuseong-gu, Daejeon, 34054, Korea, Tel: +82 423849706; Email: [email protected] Abstract In order to evaluate the adhesion performance, tack, peel strength, shear strength, and water solubility of pressure- sensitive adhesive (PSA), we prepared PSA copolymers using 2-ethyl hexyl acrylate (2-EHA), butyl acrylate (BA) and acrylic acid (AA) with varying AA contents through solution polymerization in methanol. After preparing the PSAs, we neutralized the AA in the PSAs with potassium hydroxide (KOH). Polypropylene glycol (PPG) was blended with the PSAs as a surfactant before testing adhesion performance and water solubility. Tack was characterized by probe tack testing, shear strength was evaluated with these hear adhesion failure temperature (SAFT) method, and peel strength was measured by 180° peel testing. The water solubility test was performed by comparing weight of before immersing the PSA blends in distilled water and after removing the PSAs blends from water. Water solubility was increased along within creased AA and PPG contents in the PSA blends. Keywords: Water-Soluble; Pressure sensitive Adhesive; PSA; Acrylic Abbreviations: PSA: Pressure-Sensitive Adhesive; 2- problems in paper-making such a sit becoming stuck to EHA: 2-Ethylhexyl Acrylate; SAFT: Shear Adhesion Failure the felts, wires, and dryer cylinders of paper machines, Temperature; TAPPI: Technical Association of Pulp and thus causing web breaks, reducing production, and Paper Industry (TAPPI). lowering the quality of the recycled paper [4]. Among them, PSAs are the main obstacles in repulping and Introduction paper-making. As the need for environmental protection increases, so The utilization rate of recycled paper rose from 31% has the interest in the protection of forests, and many in 1991 to 39% in 1996 in the U.S.A., from 50% to 60% in studies have been conducted on the repulping and Germany, from 60% to 70% in the U.K., from 46% to 49% recycling of waste paper in the paper industry [1-6]. in France, and from 32% to 35% in China. However, the However the recycled fiber has many contaminants such annual cost of stickies to the U.S. paper industry is as stickies, low Tg derived from ink, coating material, estimated to be about $600,000,000 –$650,000,000 [4]. pressure-sensitive adhesive (PSA), etc., which create Therefore, much research has been completed focusing on Preparation and Characterization of Water-soluble Acrylic Pressure Sensitive Adhesive J Waste Manage Xenobio 2 Open Access Journal of Waste Management & Xenobiotics sticky control and development of new PSAs. Although Analysis of PSAs stickies can be reduced by treating paper-making The glass transition temperature (Tg) was measured machines and adding dispersion agents, when the pH, using a differential scanning calorimeter (DSC, TA temperature, concentration, charge, and shear force Instrument Co. Q-1000) from -80°C to 200°C at a rate of conditions change, stickies can accumulate on paper 10°C/min. The molecular weight was measured using gel machine felt, wire, dryers, and other places [1-3,5-6]. So permeation chromatography (GPC, Waters 486). new PSAs for the repulping process must be developed [1-3]. Adhesion Performance of PSA blends In this study, water soluble PSAs were polymerized PSA performance was evaluated by probe tack, peel through solution polymerization using 2-ethylhexyl strength and SAFT testing. The probe tack and peel acrylate (2-EHA), butyl acrylate (BA), and acrylic acid (AA) strength tests were conducted using a Texture Analyzer with varying AA contents. Synthesized PSAs were (Stable Micro Systems, TA-XT2i). The probe tack test was neutralized with potassium hydroxide (KOH) and blended carried out with a polished stainless steel cylinder probe with polypropylene glycol (PPG). Adhesion performance 5mm in diameter, a separation rate of 0.5 mm/sec. under 2 of the prepared PSAs was evaluated by probe tack, peel a constant pressure of 100 gf/cm and a dwell time of 1 strength, and shear adhesion failure temperature (SAFT) second. The peel strength test was performed at an angle testing. The water solubility of each PSA was also tested. of 180° with a cross-head speed of 300 mm/min after keeping the sample at room temperature for 1 hr. For Materials and Methods SAFT, the PSA samples were pressed onto SUS (Stainless steel) (Bonding area of 25 mm × 25 mm) with two passes Materials of a 2 kg rubber-roller. A load of 1 kg was attached to one end of the lap shear, while the bonded area was adhered 2-EHA, BA, and AA used to prepare acrylic PSAs were to the stainless steel substrate. The failure temperature obtained from Junsei Chemicals Co. and used as received. was measured as the temperature was increased at 2,2-Azobisisobutyronitrile (AIBN), methanol (Duksan 0.4°C/min. pure chemical Co.), KOH (Deajung Chemicals Co.), and PPG (PPG, Mn~1000, sigma-aldrich) were used without further purification. Water solubility of PSA Blends 5 g of dried of PSA was added to 200 mL of distilled Preparation of PSAs water and the mixture was agitated at 50°C for an hour. The weight ratio was calculated using the following The acrylic PSAs were prepared through solution equation after measuring the weight of the adhesive polymerization as 50% solids in methanol. Methanol was remaining on the filter after filtering through a 300 mesh added to a 500-ml reaction tank and stirred at 65°C at 200 filter made of SUS. rpm. Then, monomer mixture having the same composition as Table 1 was added and stirred at 65°C for W 7 hours. The polymerized PSA was transferred to a PE Water-solubility (%) a 100 container and left at room temperature for 48 hours to Wb confirm the stability of the polymer. KOH was dissolved in Wa : weight of PSA after filtered water and methanol at a weight ratio of 200: 100: 100 to Wb : weight of PSA before filtered prepare a 50% solution. The molar ratio of each AA of the polymerized PSA was neutralized with KOH solution. Repulpability of PSA Blends Then, PPG was blended with 10 wt%, 20 wt%, 30 wt%, 40 wt%, and 50 wt% of the solid content of the neutralized The coated PSA was transferred to copy paper. The PSAs. paper was torn into small pieces and soaked in distilled water with a 10% consistency for 1 hr. The mixture was 2-EHA (wt%) BA (wt%) AA (wt%) disintegrated in a standard disintegrator with the propeller operating at 3000 rpm. A hand sheet was made A-5 20 75 5 according to Technical Association of Pulp and Paper A-10 20 70 10 Industry (TAPPI) standard method T 261. The sticky A-15 20 65 15 particles on the hand sheet were identified by unaided A-20 20 60 20 visual means. Table 1: PSA Co-Polymer Formulations. Juhyeon L and Jaehee L. Preparation and Characterization of Water-soluble Acrylic Pressure Copyright© Juhyeon L and Jaehee L. Sensitive Adhesive. J Waste Manage Xenobio 2018, 1(2): 000110. 3 Open Access Journal of Waste Management & Xenobiotics Results and Discussion and A-15, the tack value was increased and maintained. However, with the addition of 40 wt% or more, Table 2 shows the Tg and molecular weight of the fibrillation occurred during probe debonding and tack polymerized PSAs. As the theoretical Tg of the AA was decreased. This is because the internal cohesion exceeded 100℃, the Tg of the polymerized PSA tended to increased by the KOH is gradually relaxed by the addition increase as the content of AA increased. The acrylic PSA is of PPG and exceeds the critical point of the PPG content, a random copolymer having -30℃ ~ -40℃ of Tg [7-9]. causing fibrillation. This cohesive failure phenomenon When the content of AA in the PSAs increases, Tg also occurred with 40% or more PPG when peel strength increases and physical cross linking occurs due to was measured. When the content of PPG was 0 wt% the hydrogen bonding by the carboxyl group so that the peel strength was not measured for all samples, but the cohesive force is increased. As a result, the tack is lowered peel strength increased as the content of PPG increased. due to the decrease in intermolecular fluidity and the As the amount of PPG added increased, the peel strength adhesion to the substrate is subsequently lowered as well and tack values of A-5, A-10, and A-15 increased and then [9]. decreased, but A-20 showed a different tendency. A-20 exhibited low peel strength from 0 ~ 30wt% PPG and 4 showed cohesive failure at 40wt%.This caused molecular Experimented Tg (℃) Mw× 10 entanglement due to side-chain growth induced by the A-5 -40.9 36 chain-transfer phenomenon during polymerization, and A-10 -32.6 47 due to ionic bonding by KOH. As a result, the molecular A-15 -24.3 40 fluidity was lowered, resulting in lowered peel strength A-20 -8.5 35 and tack. SAFT results showed that SAFT increased when increasing the AA content, but SAFT decreased when Table 2: Tg and Molecular Weight of PSA Copolymers with increasing the amount of PPG in A-5, A-10, and A-15.This Varied AA Contents. is because the PSA ion-bonded by the KOH exhibits heat resistance when the amount of the PPG added is low The increased AA affected the molecular weight.
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