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A novel cyclocarbonate based technology for isocyanate free polyurethane / Poonam R. Datir in PAINTINDIA, Vol. LVII, N° 5 (05/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 5 (05/2007) . - p. 71-88 Titre : A novel cyclocarbonate based technology for isocyanate free polyurethane Type de document : texte imprimé Auteurs : Poonam R. Datir, Auteur Année de publication : 2007 Article en page(s) : p. 71-88 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Résistance au rayonnement ultraviolet Revêtements bi-composant Revêtements sans isocyanates Index. décimale : 667.9 Revêtements et enduits Résumé : The correct requirements of product development is "Gentle to the Earth and living environment" philosophy. Today's customer is much more educated and sophisticated when contemplating materials to a definite space. Also, increasing global awareness of the need to protect our environment and safeguard the health of the employees and consumers creates the demand for developing "green" products in coatings and this has become a significant driver for innovation today. Two-component urethane chemistry continues to be the leading technology for high performance coating systems. With a proven track record of polyurethane coating, known for its good UV-resistance, aesthetic and non-yellowing properties that span decades, why polyurethanes are apparently under the gun so much these days? The answer has to do with the safety implications associated with the group called as "Isocyanate (-N-C=O)". It is this highly reactive isocyanate group in a polyisocyanate molecule that co-reacts with the active hydrogen atom of a polyol to form two component polyurethane. These concerns regarding the toxicity of isocyanates has led to the development of ambient curing Non Isocyanate Polyurethanes (NIPU). Synthesis of NIPU is based on reaction of cyclocarbonate and amine that does not use the toxic material like isocyanate. Cyclocarbonates can be synthesized from corresponding epoxy precursors. The synthesized cyclocarbonates are reacted further with primary amines to get linear or network non isocyanate based polyurethanes. These non - isocyanate polyurethanes are modified polyurethane material with lower permeability, increased resistance properties with safe manufacturing process, when compared to conventional polyurethane. NIPU systems displaying UV stability, thermal stability, chemical resistance and fire resistance along with water solubility have been described in this paper. Note de contenu : - Chemistry of polyurethanes - Advantages of polyurethanes - Need to develop isocyanate free polyurethane - Non-isocyanate polyurethane (NIPU) - Advantages of NIPU over conventional PU - Toxicity of amines as compared to isocyanates - Hybrid non-isocyanate polyurethane (HNIPU) - Applications - Advances in NIPU-water soluble NIPU - Commercial aspect of NIPU Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11484 [article]

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Novel heat resistant aqueous dispersions containing phthalazinone / Z. Y. Liu in PAINTINDIA, Vol. LVII, N° 5 (05/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 5 (05/2007) . - p. 89-100 Titre : Novel heat resistant aqueous dispersions containing phthalazinone Type de document : texte imprimé Auteurs : Z. Y. Liu, Auteur ; J. Y. Wang, Auteur ; Q. L. Yan, Auteur ; Y. Kou, Auteur ; X. G. Jian, Auteur Année de publication : 2007 Article en page(s) : p. 89-100 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Dispersions et suspensions Hydrophilie Polyphthalazinone éther nitrile cétones Revêtements en phase aqueuse:Peinture en phase aqueuse Index. décimale : 667.9 Revêtements et enduits Résumé : Poly(phthalazinone ether nitrile ketone)s (PPENK) modified with NaOH was studied in order to find a hydrophilic resin applied in heat-resistant waterborne coatings. The properties ofhydrolyzates, HPPENKa (0.5 h), HPPENKb (1.5 h) and HPPENKc (3.5 h), were measured by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle (water) and solubility. The structures ofhydrolyzates were confirmed by FT IR and 1H-NMR. The results indicated that the nitrile groups conversion ratio and Ts of hydrolyzates increased whereas the weight loss ratio of HPPENK decreased as hydrolysis time was prolonged. As expected, the hydrophilicity of HPPENK was improved greatly, e.g. when CN conversion ratio was 93.82%, the water contact angles was decreased from 75. 3° of PPENK to 54. 4° of HPPENK. By studying the effect of the different reaction co-solvents, reaction temperature and NaOH concentration on hydrolysis, the optimal synthetic technology could be concluded that it is of 6 N NaOH solution and DMAc as cosolvent at 120°C. Aqueous dispersions based on three modified resins were prepared and their storable stability was in the following order: HPPENKc >HPPENKb >HPPENKa. Especially, the HPPENKc dispersion was not found deposition more than 30 days and played good film-forming property. Cured film properties of HPPENKc as follows: pencil rigidity (6 H), thermal impact resistance (300°C, 24 h), adhesion (grade 1). Curing agents were applied in dispersion, such as Hexamethoxymethyl melamine(HMMM), epichlorohydrin (ECH), triethanol amine, glycerol, etc, among them, HMMM and ECH played excellent curing property. The cooperating emulsification of Span and Tween could improve stability of HPPENK dispersion. Note de contenu : - Structural characterization - The effect of reaction time on thermal stability of hydrolyzates - The effect of different alkali concentration on hydrolysis - Co-solvents in hydrolysis - Hydrolysis reaction temperature - The effect of different reaction time on hydrophilicity and solubility of hydrolyzates - Shelf-life - Curing agents - Emulsifier - Heat resistant properties of cured film of HPPENK Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11485 [article]

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Studies on epoxy resin curatives and their applications / Garima Tripathi in PAINTINDIA, Vol. LVII, N° 5 (05/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 5 (05/2007) . - p. 101-107 Titre : Studies on epoxy resin curatives and their applications Type de document : texte imprimé Auteurs : Garima Tripathi, Auteur ; Ranjana Yadav, Auteur ; Deepak Srivastava, Auteur Année de publication : 2007 Article en page(s) : p. 101-107 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Epoxydes Réticulants Réticulation (polymérisation) Revêtements:Peinture Index. décimale : 667.9 Revêtements et enduits Résumé : The curing process is a chemical reaction in which the epoxide groups in epoxy resin reacts with such a curing agent (hardener) to form a highly cross linked, three- dimensional network. To convert epoxy resins into a hard, infusible and rigid material, it is necessary to cure the resin with hardener. Epoxy resins cure quickly and easily at partially any temperature from ambient-150°C depending on the choice of curing agent. A wide variety of curing agents for epoxy resins are available depending upon the process and properties required. The commonly used curing agents for epoxies include amines, polyamides, phenolic resins., anhydrides etc The cure kinetics and the Tg of the cured system are dependent on the molecular structure of the hardener. When selecting resin-curative combination the applications or end use defines the resin characteristics that must be built into a particular system. The materials have been separated into the general categories of room-temperature cure, room or elevated temperature elevated cure and miscellaneous curatives. In some cases a single curative or class of curatives may fit in more than one of these categories.The present article deals with the recent development, properties and modified applications of epoxy curatives. Note de contenu : - Epoxy curatives - Room temperature curing agents - Selection factor - Room or elevated temperature curing agents - Elevated temperature curatives - Miscellaneous uses - Relationship between cured epoxy resin structure and properties Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11486 [article]

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Reactive and non reactive ketonic resins / L. T. Gangotri in PAINTINDIA, Vol. LVII, N° 5 (05/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 5 (05/2007) . - p. 109-116 Titre : Reactive and non reactive ketonic resins Type de document : texte imprimé Auteurs : L. T. Gangotri, Auteur ; Milind Kale, Auteur Année de publication : 2007 Article en page(s) : p. 109-116 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Polycyclohexanones Index. décimale : 667.9 Revêtements et enduits Résumé : Reactive and non reactive ketonic resins of molecular weight 1000 were prepared by choosing proper mole ratios of cyclohexanone and formaldehyde. The heat effect on these resins was evaluated at 110°C, 150°C, and 200°C for 1, 2, and 3 hours. The study showed that the softening point of reactive ketonic resins increased to 139°C while that of non reactive ketonic resins raised only up to 112°C. Addition of plasticizer was found to increase the flexibility and adhesion of these resins considerably with excellent resistance to water and chemicals. The effect of stoving of reactive ketonic resin was found to increase the scratch resistance from 200 to 900 grams with excellent solvent resistance. Note de contenu : - Composition of ketonic resin - Preparation of ketonic resin - Effect of heat on softening point - Effect of plasticization on film properties - Effect of stoving on film properties Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11487 [article]

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Stabilization of titanium dioxide in non-aqueous and aqueous coatings / Gururaj Moharir in PAINTINDIA, Vol. LVII, N° 5 (05/2007)

[article]  inPAINTINDIA > Vol. LVII, N° 5 (05/2007) . - p. 123-125 Titre : Stabilization of titanium dioxide in non-aqueous and aqueous coatings Type de document : texte imprimé Auteurs : Gururaj Moharir, Auteur Année de publication : 2007 Article en page(s) : p. 123-125 Langues : Anglais (eng) Catégories : Dioxyde de silicium Dioxyde de titane Dispersions et suspensions Mouillage (chimie des surfaces) Revêtements -- Additifs Stabilisants (chimie) Index. décimale : 667.9 Revêtements et enduits Résumé : The inorganic treatment of commercially available titanium dioxide pigments determines to a large extent which type of wetting and dispersing additive will work best for that individual pigment type. For basic surface treatments, anionic and electroneutral additives provide the best deflocculation. For neutral surface treatments, electroneutral additives are best, while cationic additives work best with acidic SiO2- treated pigments. The isoelectric point of each pigment can be used to select the best additive. Wetting and dispersing additives provide not only a high level of pigment stabilization, but may also significantly improve the chalking resistance and durability of high-gloss topcoats. Note de contenu : - Titanium dioxide for coatings - Additives for wetting, dispersion and stabilization of TiO2 - Additives to stabilize TiO2 dosage level - Selection of the optimal additive chemistry - Additive selection and TiO2 isoelectric point - Side effects of using wetting and dispersing additives Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=11488 [article]

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