Novel ambient temperature curable two-component waterborne silicone-acrylic coatings

Waterborne coatings are composed of resins containing hydrophilic functional groups. These groups usually remain in the coating film and can adversely affect film properties such as weatherability and resistance to water and alkali. We have developed a novel ambient temperature curable waterborne two-component system, in which the hydrophilic functional groups are consumed by the crosslinking reaction. The new coating system consists of a waterborne acrylic resin containing both tert-amino and carboxylic acid groups and a hardener containing both epoxy and alkoxysilyl groups. The waterborne silicone acrylic coatings provide superior film properties even if the acrylic resin has relatively low functional group content. In this paper we describe the crosslinking reaction mechanism and film properties using some acrylic resin types and paint formulations as examples. Presented at the 24th Annual Waterborne, High-Solids, and Powder Coatings Symposium, on February 5–7, 1997, in New Orleans, LA. 1-3 Takasago, Takaishi-shi, Osaka, Japan.     

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films

The effects of latex coalescence and interfacial crosslinking on the mechanical properties of latex films were extensively investigated by means of several series of model latexes with varying backbone polymer crosslinking density and interfacial crosslinking functional groups. It was found that the tensile strength of crosslinked model latex films increased with increasing gel content (i.e. crosslinking density) of latex backbone polymers up to about 75% and then decreased with further increase in gel, while their elongation at break steadily decreased with increasing gel content. These findings showed that latex particle coalescence was retarded above a gel content of about 75% so that the limited coalescence of latex particles containing gel contents higher than 75% prevented the tensile strength of crosslinked latex films from increasing by further crosslinking the latex backbone polymers. This was contrary to the theory of rubber elasticity that the tensile strength increases with increasing molecular weight and crosslinking density. This limitation was found to be overcome by the interfacial crosslinking among latex particles during film formation and curing. This paper will discuss the effects of both latex backbone polymer and interfacial crosslinking on latex film properties. It will also discuss the development of self-curable latex blends and structured latexes containing co-reactive groups: oxazoline and carboxylic groups.     

Urethane/acrylic composite polymer emulsions

Blends of waterborne urethane and acrylic polymer systems were studied to obtain a composite emulsion that would have all of the advantages of the two polymers without their associated disadvantages. An approach to achieve extensive polymer-polymer interactions through crosslinking reactions was studied to optimize the positive aspects of each polymer. The crosslink system used an acrylic polymer emulsion containing keto or aldo groups and a polyurethane dispersion incorporating a hydrazine group. The degree of crosslinking was determined by FT-IR Single package, ambient temperature crosslinking emulsions were obtained by using this system. In addition to the excellent properties these two polymers normally possess, the crosslinked blends exhibit synergistic effects in film properties, such as good solvent resistance and low heat sensitivity over a wide range. Composite polymers of this type could be useful in applications where high durability is required: tennis court coatings, floor coatings, laminating adhesives. and paper and textile finishes.     

Caseinate based biodegradable films with improved water resistance

Proteins are considered as an interesting alternative to traditional synthetic polymers in packaging applications. Sodium caseinate based films can be used in such area, but some of their properties need to be improved. The objective of this work was to improve water resistance of caseinate based films plasticized with triethanolamine (TEA). First, plasticized films were crosslinked by formaldehyde (HCHO) or by electron beam irradiation. The crosslinking efficiency was correlated to the decrease of protein solubility in water determined from a 280 nm absorbance method. The comparison between the two crosslinking methods showed that formaldehyde crosslinking was significantly more efficient than irradiation. The HCHO crosslinking technique was selected for the following of the study. Nevertheless, even for highly crosslinked samples, the plasticizer exuded out of the film. A second part of this work was focused on the effect of surface modification on plasticizer exudation in TEA plasticized caseinate films. Considering that silicone grease coating onto the film surface was able to control TEA exudation, surface modifying additives (SMA) based on NaCAS and organo‐silicones were used to modify films surface properties. Surface wettability and energy were determined from contact angle measurements. TEA exudation ratios in water were also monitored for films containing SMA. SMA were less efficient in controlling TEA exudation rates but could significantly reduce surface energy to 42 mJ m². © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Chemical reactions of polymer crosslinking and post-crosslinking at room and medium temperature

This review focuses on various strategies that enable the crosslinking and post-crosslinking of polymers, excluding crosslinking obtained by radiation (e.g., X-ray, UV, etc.) and that at high temperature. The review is divided into two main parts: systems enabling crosslinking at room temperature and those for which crosslinking occurs at intermediate temperatures (<150 °C). In the first part, various key functional groups can be used, such as (i) carboxylic acid involving reactions with compounds that bear carbodiimide or aziridine functions; (ii) acetoacetyl groups (with isocyanate, activated alkenes, aldehyde, amine functions); (iii) reactions involving activated amines with carbonyl functions (aldehydes, ketones, etc.); (iv) species bearing acetals as pH-sensitive crosslinking agents since they are stable in basic medium but they can self react under acidic conditions; (v) acrylamide functions which are able to self-crosslink; (vi) crosslinking agents able to react with water (such as species that bear a poly(alkoxy)silane for sol-gel process) and derivatives containing isocyanate functions and (vii) systems that require oxygen, for example polymers bearing double bonds, boranes for generating hydroperoxides and acetylenic functions which undergo acetylenic coupling. The second series of systems, used at higher temperatures (yet below 150 °C) involving the following key functions: (i) carboxylic acid that react with oxazoline, or epoxide function where specific catalysts are necessary; (ii) alcohols reacting with protected urethanes, azlactones and methylol amide (for coating applications); (iii) azetidines (obtained from a cyclic amine onto an activated double bond) which self-crosslink; (iv) reversible Diels-Alder reaction (such as furane/bismaleimide reaction), and (v) Huisgen reactions between azido and triple bond.Various examples are presented, along with a discussion of their properties and applications.     

A new resin system for super high solids coating

This paper concerns a super high solids coating composed of two polymers; a silicone polymer containing SiH groups, and an acrylic or polyether polymer containing C=C groups. The silicone polymer was prepared by the equilibrium reaction of SiH containing polysiloxane and other organosiloxanes in the presence of sulfuric acid. Acrylic polymers were obtained by free radical polymerization of a monomer having an alkenyl group and other vinyl monomers. Homogeneous clear paints were available by adjusting compatibility of polymers, and VOCs of the paints were very low due to the low viscosity of a silicone polymer and the absence of polar functional groups in the coating system. The crosslinking reaction of this coating occurred through the hydrosilylation reaction between SiH and C=C groups. The performances of cured films, such as etch resistance and durability, were excellent.     

Hydrophobic polymers as barrier dispersion coatings

The aim of this study was to evaluate the properties of polymer dispersions prepared from hydrophobic monomers as barrier coatings. These dispersions were produced using a new emulsion polymerization process involving cyclodextrin as a phase‐transport catalyst. Conventional emulsion polymerization techniques are not applicable due to the low water solubility of the monomers, such as lauryl and stearyl (meth)‐acrylates. The experimental polymers showed improvements in water and water vapor barriers, as a result of the incorporation of hydrophobic monomers. The barrier properties could be further improved with functional groups, crosslinking, and chain‐regulating agents, as well as fillers. Grease and water barriers were strongly affected by pinholes, and functional monomers appeared to be effective in enhancing the grease barrier property. Particle morphology, glass transition temperature, and drying affected the performance of these dispersions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1958–1962, 2006     

Deacetylation behavior of binary blend films of cellulose acetate and various polymers

For binary blend films of cellulose acetate (CA) and various polymers, the elution behavior of the polymers from the CA films in different environments (i.e., soil, water) was examined. For the CA film containing poly(ethylene glycol) (PEG), the PEG eluted to the periphery of the film completely. On the other hand, polyvinylpyrrolidone blended with CA remained in the CA film. A CA film containing acrylic acid was prepared, and this film was heated. The elution of acrylic acid was inhibited by its polymerization. These results suggested that the internal polymers were capable of remaining in the CA film by polymer entanglement. Second, we examined the deacetylation and biodegradation behavior of CA films containing polymers with a phosphoric acid moiety in the side chain, such as poly(2‐hydroxyethyl methacrylate phosphoric acid ester) [poly(HEMA‐P)]. Poly(HEMA‐P) had the ability to deacetylate the CA, and the biodegradation rate of the CA films containing poly(HEMA‐P) increased in comparison with that of the nonadditive CA films. The elution of internal 2‐hydroxyethyl methacrylate phosphoric acid ester was inhibited by the copolymerization with 2‐hydroxyethyl methacrylate or crosslinking. In the case of both 2‐hydroxyethyl methacrylate phenyl phosphoric acid ester and 10‐methacryloyloxydecyl dihydrogen phosphate, the acetone‐soluble polymers were obtained by radical polymerization in a mixture of acetone and water. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1816–1823, 2006     

Fundamental water and salt transport properties of polymeric materials

Fundamental water and salt transport properties of polymers are critical for applications such as reverse osmosis (RO), nanofiltration (NF), forward osmosis (FO), pressure-retarded osmosis (PRO), and membrane capacitive deionization (MCDI) that require controlled water and salt transport. Key developments in the field of water and salt transport in polymer membranes are reviewed, and a survey of polymers considered for such applications is provided. Many polymers considered for such applications contain charged functional groups, such as sulfonate groups, that can dissociate in the presence of water. Water and ion transport data from the literature are reviewed to highlight the similarities and differences between charged and uncharged polymers. Additionally, the influence of other polymer structure characteristics, such as cross-linking and morphology in phase separated systems, on water and salt transport properties is discussed. The role of free volume on water and salt transport properties is discussed. The solution–diffusion model, which describes the transport of water and ions in nonporous polymers, is used as a framework for discussing structure/property relations in polymers related to water and salt transport properties. Areas where current knowledge is limited and opportunities for further research are also noted.     

Modification of aqueous polyurethanes via latex AB crosslinked polymers

A series of Latex AB crosslinked polymers have been synthesized from polyurethane (PU) (polymer A) and polystyrene (PS) (polymer B). The effect of PU/PS composition, crosslinking density in the PS domain, as well as in PU has been studied in terms of dispersion size, TEM morphology, mechanical, dynamic mechanical properties, in addition to swellability in water and toluene of the dispersion cast film. An inverted core (PS)‐shell (PU) morphology with very fine (tens of nanometers) dispersion was obtained, and the film properties were well controlled by the Latex composition and crosslinking density of both phases. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1315–1322, 2001     

乙酰乙酸基甲基丙烯酸乙酯/乙二胺体系对室温自交联苯丙乳液性能的影响

为克服线型结构苯丙乳液聚合物的缺点,采用半连续种子预乳化工艺在乳液聚合中引入乙酰乙酸基甲基丙烯酸乙酯(AAEM),以乙二胺(EDA)为交联剂,获得室温自交联苯丙乳液。研究了AAEM/EDA体系对苯丙乳液聚合物性能的影响,以及在水性涂料中的应用。结果表明,该体系能够在苯丙乳液成膜时发生室温自交联,提高聚合物的耐水性、耐溶剂性、热稳定性与物理机械性能,并改善苯丙乳液涂料漆膜的光泽、耐洗刷性、附着力、耐盐水性与耐盐雾性。     

Crosslinking of latex polymers

The physicomechanical properties and processes of thermal crosslinking of latex acrylic polymer films containing functional groups of different chemical nature were studied. Improvement of properties characteristic of latex copolymers containing methylolamide groups is explained by orientated location of hydrophilic groups on the surface of latex particles during emulsion copolymerisation, that, in its turn, leads to a more ordered arrangement of macrochains. An optimum content of methylolamide groups as regards crosslinking processes was established and explained by steric location of these groups on the surfaces of latex particles. A similar optimum is not observed for crosslinking by watersoluble resin of latex copolymers containing groups of hydrophobic glycidylmethacrylate.     

Improvement of polyvinyl alcohol/casein blend film properties by adding cellulose nanocrystals

This study aims to prepare and examine the properties of poly(vinyl alcohol)/casein (PVA/CAS) based films reinforced with cellulose nanocrystals (NC), which can be presented as an alternative to petroleum-based polymer packaging materials. PVA/CAS and 0.5–1–3–5 wt% NC containing PVA/CAS biocomposite films were prepared by solution casting method. Afterward, the 1NC film, which exhibited the best mechanical properties, was crosslinked with various amounts of glyoxal. Structural, morphological (polarized optical microscope), mechanical (tensile), thermal (differential scanning calorimetry, thermogravimetric analysis), contact angle, and water vapor transmission rate (WVTR) properties of the samples were investigated. The 1NC film exhibited the highest tensile strength (TS) and elongation values in PVA/CAS/NC films, and its mechanical properties decreased due to agglomeration with increasing NC amount. As expected, crosslinking improved the TS. The thermal stability of the PVA/CAS film was generally improved with the addition of NC and crosslinking. The high WVTR value of the PVA/CAS film decreased with the addition of NC and the 1NC film presented the lowest value. Thanks to the complex structure formed as a result of crosslinking and the reduced free volume, the WVTR of the 1NC film has reduced. The results showed that PVA/CAS-based films with good mechanical properties and water vapor barrier are promising as packaging materials.     

Syntheses and the Main Properties of Fiban Fibrous Ion Exchangers

The works on synthesis and main properties of fibrous ion exchangers are reviewed in the paper. The main attention is paid to the FIBAN materials found practical applications in water treatment and air purification processes. The following methods for preparation of ion exchange fibers have been considered: mechanical mixing of inert fiber‐forming polymer solutions or melts with finely dispersed ion‐exchangers with their following spinning into fibers; preparation of composite fibers containing polymeric reinforcement in the polyelectrolyte body; spinning of specially prepared polymers containing ionizable groups and having fiber‐forming properties; grafting of ionogenic polymers (or polymers in which ionogenic groups can be introduced after grafting) onto polymer chains of the existing polymer fiber; polymer analogues conversion of existing polymeric fibers by introducing in their structure ionizable functional groups. Conditions for preparation of ion exchange fibers with high exchange capacity, optimal swelling and acceptable mechanical properties have been outlined.     

Hydroresin dispersions: tailoring morphology of latex particles and films

Hydroresin dispersions are a new class of emulsifier free polyacrylate secondary dispersions. They are prepared by the emulsification of self-emulsifying polymer blends in water. The blends typically consist of two polymers, one is a salt group containing copolymer, the other is a hydrophobic polymer without salt groups. The particle diameters can be controlled by the amount of salt group containing polymer and the concentration of salt groups in this polymer. One advantage over conventional secondary dispersions is the fact that they are not only water dilutable but free of organic solvents. Another advantage is the extremely low content of hydrophilic salt groups in the resulting polymer mixture, which leads to very hydrophobic films. The application properties of these aqueous systems are more similar to those of organic polymer solutions than to conventional emulsion polymers. Applications of these surfactant free binders are in areas such as solvent face road marking paints and corrosion protection coatings without active pigments. The technique for the preparation of hydroresin dispersions is also useful for the creation of latex particles with core-shell structures. Two examples are given, which differ in the glass transition temperature of both the cores and the shells. From these dispersions, films with defined morphology can be prepared. A blending of the polymers with hydrophobic low molecular weight compounds, before the emulsification step, is also possible. It can be used for the incorporation of additional functions into the latex particles. As an example, the loading of latexes with a hydrophobic fluorescent dye is given.     

Surface modification using bio‐inspired adhesive polymers based on polyaspartamide derivatives

The catechol functional group of dopamine (3,4‐dihydroxyphenethylamine) has the ability to form strong adhesive bonds to inorganic and organic surfaces in aqueous environments. In this study, novel adhesive polyaspartamides containing catechol pendant groups were synthesized from polysuccinimide through successive aminolysis reactions with quantitative dopamine and ethylenediamine. The adhesion and crosslinking of dopamine‐modified polyaspartamide in aqueous alkaline media was used successfully to modify the surface of various materials (including synthetic polymers, metals, metal oxides, ceramics) using a simple immersion method. Contact angle measurements, SEM and X‐ray photoelectron spectroscopy of the modified surfaces were used to verify the surface coating on a variety of materials with very different inherent wetting properties. These novel biocompatible polymers have potential industrial and biomedical applications as adhesives or coating materials for functional surface modification. Copyright © 2011 Society of Chemical Industry     

功能液晶聚酯

综述了新型功能液日聚酯材料的大分子链结构、液晶相变温度与应用前景。这类功能液晶聚酯或者其主链含有大量碳碳双键，或者其侧链上含有大量氟碳链节或偶氮链节。功能液日聚酯的玻璃化转变温度和液日相变温度通常比传统高强度、高模量液日聚酯要低，尤其具有高强度、高模量液晶聚酯所不具备的特殊性能，如交联化、凝胶和感光作用，使其可以作为全息储存膜和其他功能材料。     

自交联型聚氨酯-丙烯酸酯复合乳液的合成研究

采用原位乳液聚合法,引入分子间交联的交联结构,制备了酮肼、环氧羧基双重自交联型聚氨酯-丙烯酸酯复合乳液,研究了交联基团对乳液及涂膜性能的影响。研究发现交联度的提高对于涂膜的硬度、耐水性、耐化学品性等有明显改进。     

Development of dense films from Melia azedarach polysaccharides

The aim of this work was to prepare dense films from polysaccharides extracted from Melia azedarach (MA) to be used e.g. in agricultural industry. Crosslinking of MA films with glutaraldehyde (Glu) through immersion method were performed. Structural features of films were elucidated by FTIR and XRD analysis. The influence of crosslinking in mechanical properties, water uptake and water vapor permeation was evaluated. Results showed neat Melia azedarach film presented high elongation and elastic modulus. Hydroxyl functional groups present in MA were reacted with glutaraldheyde to render a crosslinked matrix. It was observed through FTIR analysis that OH band reduces intensity due to the formation of acetal linkage, as the crosslinking time increases. XRD evidenced structural changes in MA arrangement with the crosslinking time. Chemical crosslinking during 12 h and 24 h rendered insoluble but less deformable films. Water uptake and water vapor permeability were reduced as the crosslinking time increased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41624.     

Reaktive polyacrylate für den oberflächenschutz

Acrylic polymers find increasing application as binders for protective coatings. The monomeric acrylic compounds easily copolymerize with each other and with many other monomers, thus permitting the synthesis of polymeric substances with very different properties. By introduction of suitable functional groups into the copolymers the synthesis of reactive polymers is possible. These products are well soluble and easily processable and can be crosslinked by the application of heat to give products of excellent chemical and mechanical resistance. The reactive groups may be introduced either by use of reactive monomers or by reaction with a suitable prepolymer. Especially acrylic polymers with hydroxyl-, amide-, N-methylolamide-, epoxy-, and active CH-groups in the molecule have received considerable attention for protective coatings. The most important types of these polymers and their crosslinking reactions are discussed with special consideration of polymers with methylolamide functions. Finally examples of important fields of application for reactive acrylic coatings are given.