Painting & Coating Industry (PCI) logo Powder coating summit logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Painting & Coating Industry (PCI) logo Powder coating summit logo
  • NEWS
    • Latest News
    • Market Trends & Reports
    • Price Alerts
    • Subscribe to eNewsletters
    • Global Top 10/ PCI 25
    • Weekly Featured Article
    • COATLE Word Game
  • PRODUCTS
    • Product News
    • Must See Products and Services
  • MATERIALS
    • Additives
    • Resins/Polymers
    • Pigments
    • Equipment
    • Distributors
  • TECHNOLOGIES
    • Adhesives
    • Architectural Coatings
    • Industrial Coatings
    • Nanotechnology
    • Powder Coatings
    • Solventborne
    • Special Purpose Coatings
    • Sustainability
    • UV Coatings
    • Waterborne
    • FINISHING
      • Finishing News
      • Finishing Technologies
      • Finishing Equipment
    • RESOURCES
      • Columns
        • Ask Joe Powder
        • Did you know?
        • Distribution Dive
        • Focus on Canada
        • Formulating With Mike
        • Innovation Insights
        • Moody's Coatings Conundrums
        • Powder Coating Perspectives
        • Target the Market
        • TiO2 Insider
      • Blogs
        • Editor's Viewpoint
        • Industry Insights
      • Coatings Supplier Handbook
      • Podcasts and Videos
        • COAT-IT! Podcast
        • Videos/PCI TV
      • PCI Store
      • eBooks
      • Sponsor Insights
      • White Papers
      • COATLE Word Game
    • EVENTS
      • Coatings Trends & Technologies Summit
      • Paint and Coatings Academy
      • Webinars
      • Calendar of Events
      • Lifetime Achievement Award
    • DIRECTORIES
      • Buyer's Guide
      • Equipment Directory
      • Materials Directory
    • EMAGAZINE
      • Current Issue
      • eMagazine Archive
      • China Issue Archive
      • Editorial Advisory Board
    • CONTACT
      • Contact Us
      • Advertise
      • Subscribe to eMagazine
      • Subscribe to eNewsletters
    Paint and Coating Resins & Polymers

    A New Tool for PUD Design

    By Maykin Aungsukiatethavorn, Philippe Barbeau
    pci0918-Vencorex-476037409-900.jpg
    September 14, 2018

    Over the past decades, polyurethane dispersions (PUDs) have increasingly gained attention in the world of material science, leading to a number of developments in several coatings and adhesives applications. This interest for PUDs is supported by the need for eco-friendly products and the trend towards waterborne systems, as well as the constant quest for superior performance. The end-use properties of a PUD are essentially defined by the structure of the polymer, and more specifically by the nature of the building blocks constituting the backbone of the macromolecules, namely diols and diisocyanates. Due to process constraints and application requirements, the choice of diisocyanates entering into the structure of PUDs is often limited to a handful of substances chosen among (cyclo)aliphatic isocyanates.

    A few years ago, Vencorex Chemicals launched a new difunctional isocyanate polymer, Tolonate™ X FLO 100, which is generally used as a crosslinker (reactive diluent) in 2K polyurethane systems. In this article we aim to investigate the potential use of its structure in PUD synthesis and the benefits in final material performance.

     

    Introduction

    PUDs are flowable, two-phase systems consisting of water and polymer, mainly made from diisocyanates and polyols (macrodiols), as well as other components such as ionizers, neutralizers and chain extenders. The most common diisocyanates used in PUD production are (cyclo)aliphatic isocyanates such as isophorone diisocyanate (IPDI) and methylene bis(cyclohexyl isocyanate) (H12MDI), mostly because of their low reactivity with water, thus enabling PUD production with limited side reaction during the aqueous dispersion phase. In addition, (cyclo)aliphatic isocyanates enable the design of light-stable resins suitable for various applications in the coatings field.

    Tolonate X FLO 100 is a partially bio-based, solvent-free and low-viscosity aliphatic difunctional isocyanate (Figure 1). It is particularly designed for producing solvent-free polyurethane and polyurea materials and/or for reducing volatile organic compound (VOC) emissions of polyurethane solvent-based formulations.

    General molecular structure of Tolonate X FLO 100
    FIGURE 1 » General molecular structure of Tolonate X FLO 100.

    Due to its atypical structure, more specifically the presence of a linear apolar side chain, Tolonate X FLO 100 is often applied for improving flexibility and hydrolytic resistance of the coating when used in the hardener system of conventional 2K polyurethanes. The objective of the present study is to investigate the impact of the Tolonate X FLO 100 structure when used as a building block of a PUD system.

    Recently, there has been consistent research to enhance PUD film properties, including flexibility as well as hydrolysis and chemical resistance. The patent of Nakamura et al. (US20110136976) has described PUDs made from H12MDI and polycarbonate polyols, of which elongation at break can be increased up to 47% from a standard recipe. Another patent of Pedain et al. (US 6,248,451/ 2001) has described PUDs produced from 4,4’ diphenylmethane diisocyanate and polyester polyols, with >5% of substances with functional groups similar to that present in the structure of Tolonate X FLO 100. It shows better chemical (ethanol 48%) and hydrolysis resistance of modified PUDs in comparison with conventional PUD recipes. Suitable applications are wood and parquet.

     

    Experimental

    The PUD experiment was set up according to the prepolymer mixing process (PMP), which comprises four theoretical steps: (1) polyaddition or prepolymerization in organic phase; (2) neutralization; (3) dispersion of prepolymer in aqueous phase; and (4) chain extension to obtain the final PUDs. The lab equipment for conducting these four steps used in our study included a jacketed stirred-tank reactor with 500-mL operating capacity, bottom outlet and reactor cap with multiple inlets. This reactor was equipped with a heating and cooling bath with an operating temperature range of 10 °C - 120 °C. The anchor-type agitator was applied in order to reduce the rod climbing or so-called “Weissenberg effect” from highly viscous liquids, especially during the chain extension step. Chemicals used in this study are described in Table 1.

    Synthesis of dichlorodimethylsilane via the Müller-Rochow synthesis
    TABLE 1 » List of chemicals used in the study.

    In each set of experiments, 50 g of PPG-1000 were used. The PPG-1000, DMPA and small amount of MEK were introduced into the jacketed stirred-tank reactor and preheated to 60 °C. Then, the isocyanate part was mixed and prepolymerized with the hydroxyl part, PPG-1000 and DMPA, at 80 °C for 4.5 hrs. After that, the prepolymer was cooled down, and made-up MEK was input to reduce prepolymer viscosity. The prepolymer was then neutralized with TEA at 60 °C and further cooled down to below 40 °C before dispersion into water. Water was input from the top of the reactor at the rate of 30-50 mL/min at a high agitation rate at approximately 500 rpm. After the prepolymer and water were visually homogenized in the reactor, diluted EDA was injected for chain extension of the dispersed prepolymer.

    The syntheses were carried out using the following parameters: isocyanate:hydroxyl (NCO:OH) ratio = 1.8, DMPA:polyol ratio = 1, neutralization degree (i.e. ratio of amine:carboxylic groups) of 70%. The polymerization in the dispersion phase was conducted until a chain extension degree (i.e. % of NCO groups available after prepolymerization phase that are reacted with EDA during chain extension) of 80% was reached. The final solid content was 35%, with co-solvent content below 4%. The molar ratios of X FLO per total NCO, in the isocyanate part, varied from 0% to approximately 20%. Table 2 summarizes the compositions of the isocyanate parts in the study.

    Parameter variation (X FLO ratio) in each experiment
    TABLE 2 » Parameter variation (X FLO ratio) in each experiment.

    The reaction kinetics during PUD synthesis were studied using Fourier Transform Infrared Spectroscopy in attenuation mode (FTIR-ATR, Tensor 27 from BRUKER). Isocyanate (NCO) groups along the synthesis were followed using the peak at 2,270 cm-1 by FTIR. The data were normalized using the surface of the alkyl functions at 2,800-3,000 cm-1. The measurements made for PUDs in the water phase were subtracted with the standard profile of water. Seven specimens at different times along the PUD synthesis were collected in each experiment to construct a kinetic profile.

    The mean particle size and particle size distribution of the final dispersion was measured using a laser diffraction granulometer (Mastersizer 2000 from MALVERN).

    The final PUDs were tested after application and drying. Dry films with thicknesses of approximately 60 microns were made by manual applicator on glass substrates, passed through flash-drying, and put in an oven at 80 °C overnight to ensure total drying. The following properties were measured: pendulum (König) hardness, scratch resistance using Taber scratch tester, hydrolysis and chemical resistance (overnight) by water and isopropanol, as well as film gloss (at 20°) and haze using a BYK Gardner 4630. Another set of thick films with estimated thickness of 1 mm was made on flat plates and left in a controlling chamber at 25 °C for at least 5 days to minimize trapped bubbles and to ensure total drying. With these thick films, ultimate tensile strength and elongation at break were measured by Uniaxial tensile testing machine MTS Insight 30kN (MTS Systems).

    Finally, glass transition temperature (Tg) was analyzed by Dynamic Mechanical Analysis (DMA, PerkinElmer DMA Q800).

     

    Results and Discussion

    Synthesis and Basic Properties of Liquid PUDs 

    Table 3 presents the characteristics of the PUDs made from the experiments X FLO-0 to X FLO-20. As seen in this table, the incorporation of 5% and 10% of Tolonate X FLO 100 did not impact the properties of PUDs in terms of particle size distribution, pH and viscosity. When the X FLO ratio was increased to around 20%, the particle size and viscosity of the final PUDs started to increase. This behavior could be attributed to side reactions with water during the dispersion of prepolymers, leading to different behaviors in the chain extension step. These side reactions with water could indeed be enhanced with increasing the amount of X FLO, as the reactivity of the NCO group is known to be higher compared to the ones of the IPDI structure.

    Basic properties of liquid PUDs with different ratios of X FLO
    TABLE 3 » Basic properties of liquid PUDs with different ratios of X FLO.

     

    Kinetic Profiles of Isocyanate Reactions

    The kinetic results in ATR-FTIR are summarized in Figure 2. The kinetic profiles were tracked in each experiment, and the results show that all experiments follow the same trends, in which amount of free NCO drops to around 45% from initial during the prepolymerization step. Then, 2-4% of NCO reacts with water in dispersion, and the majority of this further reacts with amine during the chain extension step.

    Kinetic profile summaries from experiments: X FLO-0, X FLO-5, X FLO-10 and X-FLO-20
    FIGURE 2 » Kinetic profile summaries from experiments: X FLO-0, X FLO-5, X FLO-10 and X-FLO-20.

    As described in the Experimental section, the reaction in the dispersion phase was stopped after 80% chain extension was reached, as some of the remaining NCO groups were entrapped inside polymer particles, these NCO groups will be more difficult to reach by EDA molecules during PUD synthesis. However, and with a longer period of time, all of the rest of the NCO functions will finally react, eventually with surrounding water, eventually to urea functions (see particle model proposed by Jhon et Al. (2001) in Figure 3).

    PUD particle model proposed by Jhon et al. (2001). There are different NCO locations on particle surfaces (B) or inside particles (A) where the chain extenders or water need time to penetrate and react with NCO
    FIGURE 3 » PUD particle model proposed by Jhon et al. (2001). There are different NCO locations on particle surfaces (B) or inside particles (A) where the chain extenders or water need time to penetrate and react with NCO.

     

    Physical Properties of PUD Films

    Next, films from each liquid PUD experiment were analyzed with regards to their physical properties (aspects), mechanical properties, and chemical and hydrolysis resistances. In order to assess the benefit of X FLO when incorporated in the backbone of the PUD structure, two additional films were prepared (X FLO-10x and X FLO-20x). Those two systems were made by mixing the PUDs without X FLO (X FLO-0) with Tolonate X FLO 100 directly (ratio of 4.2 % and 7.6% by weight on wet PUDs, equivalent amount to X FLO-10 and X FLO 20 respectively) before applying the films. Composition details as well as test results are summarized in Table 4.

    Film properties of PUDs produced with different X FLO proportions.
    TABLE 4 » Film properties of PUDs produced with different X FLO proportions.

    At the same weight ratio of crosslinking Tolonate X FLO in the structure, represented by comparisons of X FLO-10 vs X FLO-10x, and X FLO-20 vs X FLO-20x, the crosslinked PUDs did not show the same properties as the ones with X FLO in the backbone, simply observed from physical aspects. The hazy films indicate a phase separation from blending high-polar aqueous phases with low-polar X FLO. The consequence on mechanical properties is lower strength as well as lower elongation at break (Figure 4).

    Percentage of elongation at break and number of pendulum movement of 1K PUD samples
    FIGURE 4 » Percentage of elongation at break and number of pendulum movement of 1K PUD samples: X FLO-0, X FLO-5, X FLO-10, X-FLO-20 as well as crosslinked PUDs: X FLO-10X and X FLO-20X. The bars with arrow on top (X FLO-10 and X FLO-20) indicate the minimum value, as the film slipped out of the machine holder before it was broken from elongation..

     

    Conclusions

    Tolonate X FLO 100 can be advantageously used in the design of polyurethane dispersions. The results obtained in this study show that, by adding Tolonate X FLO 100 to conventional diisocyanate monomers like IPDI, up to 20% by mol (40% by weight) in the diisocyanate composition, Tolonate X FLO 100 does not impact the polymerization process nor the characteristics of the dispersion. The most remarkable impact is the drastic increase in flexibility and elongation at break of the final material. A direct consequence is the improvement of the scratch resistance (brittleness) of the film. Furthermore, Tolonate X FLO 100 can improve hydrophobicity of the film and chemical resistance of the coating. Additionally, being a polymer, it offers safer handling during the preparation of the PUDs compared to classic diisocyanate monomers.

    These benefits can be of great help when designing PUDs for applications requiring superior flexibility performance, such as coatings for textiles and leather finishing, and adhesives and sealants. 

     

    Acknowledgements

    The authors would like to sincerely thank all colleagues at Vencorex Chemicals for their contributions on this work, especially Philippe Olier and Remi Martinez for technical advice and expertise. Jean-Yves Martin, Muriel Ducomet and Marie-Laure Bonnefoy are also acknowledged for their kind support in technical testing and analysis.

     

    References

    1. Jhon et al., Chain Extension Study of Polyurethane Dispersions, Colloids and Surfaces, Vol. 179 (2001).

    2. Mulonda Hercule et al., Preparation & Characterization of PUDs crosslinked by Urea Bridges, International Journal of Chemistry, Vol.3, No.2 (2011).

    3. Nakamura et al., Aqueous Polyurethane Dispersion and Process for Preparing the Same, Publication number: US 20110136976 (2011) .

    4. Negim et al., The Effect of Diamine Extender on the Properties of Polyurethane Dispersions, Middle-East Journal of Scientific Research, Vol. 16 issue 7 (2013).

    5. Pedain et al., Aqueous Polyurethane Dispersions Having Improved Water and Solvent Resistance, Publication number: US 6248415 (2001).

    KEYWORDS: PUDs wood coatings

    Share This Story

    Looking for a reprint of this article?
    From high-res PDFs to custom plaques, order your copy today!

    Maykin Aungsukiatethavorn, Market Developer: South Asia Pacific, Vencorex, Bangkok
    Philippe Barbeau, New Business Development Director, Vencorex Chemicals, Saint Priest, France

    Recommended Content

    JOIN TODAY
    to unlock your recommendations.

    Already have an account? Sign In

    • PCI-0724-Global10-Feature-1440.png

      2024 Global Top 10: Top Paint and Coatings Companies

      Who ranks on top? PCI’s annual ranking of the top 10...
      Global Top 10 and PCI 25
      By: Courtney Bassett
    • PCI-0724-PCI25-Feature-1440.png

      2024 PCI 25: Top Paint and Coatings Companies

      PCI's annual ranking of the top 25 North American paint...
      Global Top 10 and PCI 25
      By: Courtney Bassett
    • pci1022-Kinaltek-Lead-1170.jpg

      A Novel Pigment Production Technology

      Following an extensive R&D program that demonstrated...
      Paint and Coating Pigments
      By: Jawad Haidar and Nitin Soni
    You must login or register in order to post a comment.

    Report Abusive Comment

    Subscribe For Free!
    • eMagazine
    • eNewsletter
    • Online Registration
    • Subscription Customer Service

    More Videos

    Sponsored Content

    Sponsored Content is a special paid section where industry companies provide high quality, objective, non-commercial content around topics of interest to the PCI audience. All Sponsored Content is supplied by the advertising company and any opinions expressed in this article are those of the author and not necessarily reflect the views of PCI or its parent company, BNP Media. Interested in participating in our Sponsored Content section? Contact your local rep!

    close
    • paint sprayer in a workshop
      Sponsored byallnex

      Enabling Performance and Compliance: allnex Introduces a New Line of VOC Exempt Solvent-Borne Resins

    • various shades of orange pigments and colorants
      Sponsored byVibrantz Technologies

      Solid Colorant Technology Paves the Way for a Sustainable, High-Performance Future in Coatings

    Popular Stories

    A collage of products using non-PFAS

    A Surge in Non-PFAS Releases

    Default Aerospace Image

    PPG Plans Major Aerospace Facility

    US tariff on British product import trade war cargo shipping container

    Tariffs Reshape Coatings Supply Strategies



    PCI Buyers Guide

    Submit a Request for Proposal (RFP) to suppliers of your choice with details on what you need with a click of a button

    Start your RFP

    Browse our Buyers Guide for manufacturers and distributors of all types of coatings products and much more!

    Find Suppliers

    Events

    January 1, 2030

    Webinar Sponsorship Information

    For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

    View All Submit An Event

    Poll

    Longest-running laboratory experiment

    What is the longest-running laboratory experiment?
    View Results Poll Archive

    Products

    Automotive Paints and Coatings, 2nd Edition

    Automotive Paints and Coatings, 2nd Edition

    Now in its second edition and still the only book of its kind, this is an authoritative treatment of all stages of the coating process.

    See More Products
    pci  webinar april 2025

    PCI CASE EBOOK

    Related Articles

    • pci0617-BYK-178449351-900.jpg

      Design and Properties of a New Easy-to-Clean Additive for Epoxy Topcoats

      See More
    • A Green Tool for Selective Oxidation Reactions

      See More
    • XPS - A Tool for the Chemical Characterization of Coatings and Interfaces

      See More

    Related Products

    See More Products
    • intelligent.jpg

      Intelligent Coatings for Corrosion Control 1st Edition

    • Kevin-Biller-PC-BOOK.jpg

      Powder Coatings - Foundation for the Novice Formulator (ebook)

    • fluorinated2e.jpg

      Fluorinated Coatings and Finishes Handbook, 2nd Edition

    See More Products
    ×

    Keep the info flowing with our eNewsletters!

    Get the latest industry updates tailored your way.

    JOIN TODAY!
    • RESOURCES
      • Advertise
      • Contact Us
      • Directories
      • Store
      • Want More
    • SIGN UP TODAY
      • Create Account
      • eMagazine
      • eNewsletters
      • Customer Service
      • Manage Preferences
    • SERVICES
      • Marketing Services
      • Reprints
      • Market Research
      • List Rental
      • Survey & Sample
    • STAY CONNECTED
      • LinkedIn
      • Facebook
      • Youtube
      • X (Twitter)
    • PRIVACY
      • PRIVACY POLICY
      • TERMS & CONDITIONS
      • DO NOT SELL MY PERSONAL INFORMATION
      • PRIVACY REQUEST
      • ACCESSIBILITY

    Copyright ©2025. All Rights Reserved BNP Media.

    Design, CMS, Hosting & Web Development :: ePublishing