用于水性体系的稳定的粘合促进剂和交联剂

有机功能烷氧基硅烷作为粘合促进剂和交联剂,广泛应用于胶粘剂、密封胶和涂料等领域。然而,传统硅烷在水性环境中的不稳定性限制了其在水性体系中的应用。本文叙述了专用于水性体系的硅烷新技术,以及新旧环氧硅烷在含有羧基和氨基基团的单组分水性胶粘剂、密封胶体系,如丙烯酸乳液、丁苯胶乳和聚氨酯分散体中的应用,并讨论了影响贮存稳定性、固经机理和性能表现的因素。     

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.     

Development of waterborne UV-A curable clear coat for car refinishes

The development of a waterborne UV-A curable clear coat for car refinish application is described. The clear coat formulations are based on specially developed acryloyl or maleimide functional polyurethane dispersions. The functional PUR dispersions are characterized by a relatively low molecular weight, a high CC functionality and an optimized amount of poly(ethylene oxide). These characteristics are necessary for obtaining optimal film formation which results in good appearance and other film properties. It was found that poly(ethylene oxide) had a positive effect on surface cure when irradiated with UV-A light (less influence of oxygen inhibition). The synthesis of PUR dispersions and their performance in clear coats are described, including several aspects on film formation (conversion of CC, AFM measurements) and film properties (durability, physical and chemical properties).     

Incidence of the polyol nature in waterborne polyurethane dispersions on their performance as coatings on stainless steel

Three waterborne polyurethane dispersions derived from polyester, polyether and polycarbonate diols with molecular weight of 1000 Da were synthesized by the acetone method and used as coatings on stainless steel 304 plates. The properties of the dispersions and the polyurethane films were influenced by the polyol nature. The polyurethanes obtained with polyether or polyester showed higher degree of phase separation between the soft and the hard segment. The higher adhesive strength under shear stresses was obtained in the joints produced with the waterborne dispersion obtained with polycarbonate diol. The properties of the polyurethane coating obtained with polycarbonate diol on stainless steel 304 were significantly higher as compared with the others. Improved performance of coatings obtained with polycarbonate diol was ascribed to the higher polarity of the carbonate groups that contributed to additional hydrogen bond formation between soft segments with respect to those obtained with polyether or polyester     

A-type zeolite containing Ag/Zn as inorganic antifungal for waterborne coating formulations

The biocide cations Ag⁺ and Zn²⁺ were hosted in the cavities of an ordered aluminosiliceous framework. Starting from sodium A-type zeolite (NaA), LTA containing Ag⁺ (AgA), Zn²⁺ (ZnA) and Ag⁺/Zn (AgZnA) at different cation exchanged levels was obtained and its antifungal properties were evaluated. To determine the minimum inhibitory concentration (MIC) of the exchanged zeolites against Aspergillus niger, [Ag⁺] and [Zn²⁺] values ranging from 50 < [Ag⁺] < 1000 mg L⁻¹ to 650 < [Zn²⁺] < 2000 mg L⁻¹, respectively, were used for NaA, and for AgZnA: 30 < Ag⁺ < 250 mg L⁻¹. The zeolite sample having [Ag⁺] = 100 mg L⁻¹, [Zn²⁺] = 90 mg L⁻¹ produces a growth inhibition comparable to that achieved with 230 mg L⁻¹ of Ag⁺¹ (MIC value obtained for the single cation). The antifungal activity of these products after incorporation in waterborne coating formulations was also determined. Results indicate that Ag⁺ and Zn²⁺ supported on A-type zeolite could be a beneficial tool for the development of waterborne coatings with a longer protection against microbiological attack when compared to traditional organic biocides.     

Properties and paper sizing application of waterborne polyurethane emulsions synthesized with isophorone diisocyanate

In this work, a two-step synthesis methodology has been used to synthesize a series of waterborne polyurethane (WPU) emulsions with isophorone diisocyanate (IPDI), poly-caprolactone diol (PCL) and dimethylol propionic acid (DMPA) as monomers and ethylenediamine (EDA) as the chain extender, respectively. The influences of the NCO/OH molar ratio, DMPA content, chemicals-adding sequence, and acetone content on the physical properties of the resultant emulsions have been investigated in detail. The results show that the emulsion viscosity increases with an increase in the NCO/OH molar ratio or DMPA content whereas it declines sharply as the acetone amount increases. The emulsion particle size is seen to increase with the NCO/OH molar ratio but it decreases as the DMPA content increases. The chemicals-adding sequence is observed to strongly affect the particle size and viscosity of the resultant emulsions. For cast films, with an increase in the NCO/OH molar ratio, the elongation monotonically decreases while the tensile strength is seen to increase at first and then deceases. The film water absorption capacity is found to go up as the DMPA content increases. Furthermore, after sized with the emulsions, the paper water resistance is markedly improved and the 30s Cobb value is seen to decrease by 63% as compared to the unsized counterpart. The paper folding resistance and the tensile index are also improved to certain extents. For producing well-performed WPU emulsions for sizing paper sheets, an NCO/OH molar ratio of 1.6–1.8 and a DMPA content of 6.0–7.0 wt.% are preferably chosen.     

High reactive CH-acidic enamines: a novel approach to two-component waterborne systems

A new CH-acidic enamine crosslinking system is described. These crosslinking resins are prepared by the reaction of acetoacetate polymers with amines to increase the CH acidity; thus it is possible to cure ,β-unsaturated resins via Michael addition at room temperature, even without strong base catalysis. Furthermore, the high reactivity of the crosslinkers allows curing in water as the solvent. Extensive curing studies via IR spectroscopy are described to investigate shelflife, and the dependence the enamine/ketimine equilibrium on curing speed, which is influenced by the polarity of the solvents. Although the enamine function can be hydrolyzed in acidic media, the crosslinked films are resistant to a multitude of both organic and inorganic compounds.     

Waterborne two-pack isocyanate-free systems for industrial coatings

Two-pack paint systems are used in various segments of the industrial coatings market. Stringent legislation concerning the emissions of organic solvents has led to an increasing demand for green alternatives, for the current solventborne products. Water, in this respect, is one of the most interesting technologies for ambient curing systems. A novel waterborne isocyanate-free two-pack system for high gloss topcoats is herewith described. The system is based on two waterborne acrylics with different functional groups. Properties of the system were compared with the performance of waterborne two-pack polyurethanes based on polyisocyanates and waterborne acrylic polyols. Solventborne versions of both two-pack systems were also used as references.     

纳米材料在水性涂料中的应用

综述了目前国内外纳米粉体在水性涂料中的分散技术，介绍了对纳米粉体进行修饰和表面包覆改性方面的研究情况，分析了目前研究中存在的问题及发展趋势。     

Characterization of waterborne acrylic based paint films and measurement of their water vapor permeabilities

Recently, production of waterborne coatings has increased significantly as a consequence of strict pollution regulations. Waterborne coatings are sensitive to humidity, thus, their barrier properties with respect to permeation of moisture needs to be determined. Among various coating constituents, binder represents the matrix structure and its amount relative to the amounts of pigments and fillers can significantly affect the structure, hence the barrier property of the coating. In this study, waterborne acrylic based paints applied as protective coating on interior and exterior wall of the buildings are studied. The paint samples formulated with four different binder contents by a commercial paint company are used in the experiments. We first determine unknown ingredients of the paint samples using different characterization tools and then investigate the effect of the binder content on the structure of the paint films. In addition, water vapor permeability of the paint films is measured using a permeation cell. Results show that the barrier property of the waterborne acrylic based paint films against humidity decreases with decreased binder content due to uneven distribution of the pigments, consequently, porous structure formation in the films.