Effect of different polymers on the efficiency of water‐borne methyl amine adduct as corrosion inhibitor for surface coatings

Styrene/acrylic emulsion copolymer and water‐based short oil urethane alkyd resin were used as binders to prepare water‐based, environmentally friendly paints by using 0.5% emulsified methylamine adduct as corrosion inhibitor. The choice of the two above‐mentioned binders was based on the fact that styrene/acrylic emulsion copolymer is a nonconvertible binder, whereas short oil urethane alkyd resin is a convertible binder. The physical, chemical, mechanical, and corrosion properties of the paint films were evaluated and compared with a commercially known anticorrosive water‐based paint. It was found that the prepared paints have unique desirable properties such as the following: they do not contain anticorrosive pigments (which contain heavy metals in their main chemical structure); they are solvent‐free; and they can be produced to match any color. Corrosion tests on the films of the formulated paints revealed that the short oil urethane alkyd resin is superior to the styrene/acrylic copolymer. Moreover, the corrosion inhibition properties of the paint films prepared from both binders are comparable with the commercially available paints containing anticorrosive pigments. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 879–885, 2002     

Structure and properties of multiphase particles and their impact on the performance of architectural coatings

Aqueous dispersions used as binders in low-pigmented solvent-free paint formulations have to cope with the challenge to simultaneously guarantee an excellent film formation and appearance as well as good block resistance and hardness. One strategy to fulfill these contradictory requirements is the employment of multiphase particles.

In this work it is proved that the structure of latex particles, synthesized by a two-stage emulsion polymerization process, can be correlated to the morphology and properties of the dispersion films as well as to the application properties of the corresponding paint films.

Two sets of model dispersions were made. In the first set, the hard/soft ratio was varied, in the second set the amount of the AA. The structure of the particles was determined by TEM, and a morphology map was derived. AFM demonstrated a clear correlation between the particle structure and the morphology of the latex film. Dynamic mechanical analyses verified the presence of two distinct polymers with the hard phase acting as a transparent filler. For the hard/soft series, the properties of the dispersion films such as block resistance, gloss and hardness could be attributed to their structure. A closer look on the block behavior revealed that it can be related to the tack and surface roughness of the dispersion film, but not to its internal strength. Solvent free emulsion gloss paints were formulated, and application tests performed. The properties of the paint films correlated very well with those of the dispersion films. The test results clearly show that dispersions of multiphase particles enable the formulation of solvent free paints with excellent film-forming ability in combination with high block resistance, hardness and gloss.     

Formulation effects on the distribution of pigment particles in paints

Modern water-borne paints are widely used in different areas of applications ranging from high-gloss lacquers to flat, scrub-resistant interior paints. From this point of view, the pigment volume concentration (PVC) is one key-parameter adjusting the desired application properties. In high-gloss paints, for example, a low PVC is required to accommodate the proper surface roughness to achieve a high gloss. Consequently, a high concentration of TiO₂ is needed to obtain a good hiding power at the same time. Flat paints nonetheless are highly filled due to cost reasons preferentially by CaCO₃ and the pigment binding capacity of the binder is crucial. In this work, paint formulations differing in PVC, and the type of binder or dispersing agent were investigated by various techniques concerning the distribution and aggregation of pigment particles, e.g. TiO₂. To get a detailed insight into the structure of the liquid paints and the corresponding dried paint films, suitable analytical tools were applied for characterization. The structure of the liquid paints was analyzed by remission light spectroscopy (RLS), disc centrifugation, cryogenic-replication transmission electron microscopy (Cryo-replica TEM) and cryogenic-scanning electron microscopy (Cryo-SEM). The pigment distribution in the corresponding dried paint films was examined by means of atomic force microscopy (AFM), TEM and RLS. The tendency of the TiO₂-pigments to form aggregates was found to depend on both: first on the type of binder used in the formulation and second on the employed dispersing agent. It is shown that only by adjusting the properties of the binder in combination with common dispersants, it is possible to get well-distributed TiO₂ particles within the paint. Correlation of application properties, e.g. gloss and blocking to the microscopic structure is presented.     

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.     

Microstructure of weathered paint and its relation to gloss loss: Computer simulation and modeling

The role of pigment particle size, pigment volume concentration, and dispersion in gloss loss of paint films on weathered surfaces is unclear. Because reproducible and cost effective data are difficult to obtain, an approach based on computer simulation and modeling is a promising supplementary tool. We describe the simulation of a painted surface consisting of pigment particles of known size, pigment volume concentration and dispersion, situated in a binder that erodes over time due to exposure to ultraviolet radiation. Pigment particle size, geometry, pigment volume concentration, and pigment particle dispersion are parameters of the model. Our purpose is to illustrate how simulation can be used to aid the development of formulation strategies for the design of coatings with desirable gloss characteristics.     

The use of new blockcopolymeric dispersing agents for waterborne paints — theoretical and practical aspects

Newly developed blockcopolymeric dispersing agents are evaluated in their performance with a number of pigments in order to obtain a deeper understanding of the dispersing process and of the factors that affect the stability of waterborne binder free pigment concentrates. Special attention is paid to the variation of the amphiphilic ionic/non-ionic and hydrophobic/hydrophilic properties of these new dispersants. By measuring particle surface charges and particle size distributions of pigment pastes and by determining relevant properties of the films obtained after application the effect of a number of binders and other paint components on the stability of dispersions is also evaluated. Guidelines for efficient and economically optimum preparation of pigmented waterborne paints are given.     

Novel anticorrosive emulsion-type paints containing organic/inorganic nanohybrid particles

Novel anticorrosive emulsion-type paints were prepared by utilizing organic/inorganic nanohybrid particles (nHPs) of composition (1:1) based on polyaniline (PANI) and nanosilica. Polyaniline (PANI) and nanosilica were synthesized via chemical oxidative and sol–gel polymerization techniques respectively. The prepared materials were characterized via (gel permeation chromatography (GPC), infra red (FT-IR), transmission electron microscope (TEM) and differential scanning calorimetry (DSC)). The binder used in this context is polyvinyl acetate (PVAc). Nanohybrid particles/PVAc emulsion composites (nHPs ECs) were simply formed by individual mixing of the prepared neat PANI and nHPs of composition (1:1) with PVAc to produce the corresponding nanohybrid particles/PVAc emulsion composites EC₁ and EC₂ respectively. The chemical and basic properties including (acid and alkali resistance, adhesion, washability, gloss, opacity, whiteness, hardness, impact, and weathering) as well as the anticorrosion properties of the blank paint films and the paint films containing neat PANI and nHPs of different concentrations (5%, 10%, and 15%) were investigated and evaluated. The obtained experimental results revealed that the presence of nHPs in the blank paint are highly enhanced both basic and anticorrosion properties of the coated films.     

Effect of quantity and size distribution of calcite filler on the quality of water borne paints

Calcite is the most widely used mineral filler in paint formulations. It provides not only a decrease in the cost of paint but also modifies some physical paint properties. Although some properties of calcite such as particle size distribution and refractive index are not comparable in quality to TiO₂, calcite can improve the distribution of TiO₂ via its interaction with TiO₂ particles. In this study, calcites of different size distributions are used as filler in the architectural waterborne, acrylic based paint recipes. The quality of paints was compared to properties based on both wet and dry paint such as viscosity, density, opacity, gloss, scrub resistance and Buchholz hardness. Examination of the results identified an optimum quantity and size distribution of calcite for the paint recipe. The second series of this study involved substitution possibilities of TiO₂ with calcite using seven different paint formulations. Phase images of the dry paint films obtained using “Atomic Force Microscopy” (AFM) showed the extent of distribution and aggregation of particles for each formulation on the paint surface. The overall experimental results revealed that the use of TiO₂ can be decreased up to 4% by replacement of calcite with an optimum size distribution that was also supported by AFM measurements.     

Control of rheology of water-borne paints using associative thickeners

Water-borne decorative topcoats generally show inferior leveling and open time compared to solvent-based paints. Basically, this behavior is caused by the divergent viscosity–solid content relationship for dispersions and emulsions and by the relatively high evaporation rate of water. Employment of associative thickeners may improve leveling and open time of latex paints only if they introduce a substantial amount of ‘network viscosity,' characterized by a short relaxation time and little dependence on solid content. This network viscosity enables one to formulate a paint with sufficient high-shear viscosity at a particle-packing density far below the value where low-shear viscosity starts to diverge. Addition of an associative thickener not only affects rheology, but also the interaction between latex particles: Associative HEUR thickeners may induce undesired phase separation by strong bridging between the latex particles. The influence of HEUR thickeners on latex particle interaction has been studied by turbidity measurements. The experimental results could qualitatively be interpreted very well by two-particle interaction potentials computed using the Self-Consistent-Field theory of Scheutjens and Fleer. It is demonstrated how viscosity, created by the addition of an associative thickener to a highly concentrated latex, can be split up into a polymer network viscosity and a contribution to (relative) dispersion viscosity. According to these analyses, reduction of the molecular weight of tri-block HEUR thickeners yields an increase of the favorable network viscosity and a reduction of the unfavorable dispersion viscosity. However, reduction of the molecular weight of the HEUR thickener is limited by the introduction of undesired phase separation (bridging flocculation) below a certain molecular weight.     

Styrol als Rohstoff für Lackbindemittel und Lacke

Styrene as Raw Material for Paint Binders and Paints Monostyrene is highly reactive and it can undergo homopolymerisation as well as mixed polymerisation. Polystyrene, which is mainly used in thermoplastic materials, can not be employed as binder for paints; thus, for example, the films adhere neither to wood nor to metal. Polystyrene does not withstand other raw materials of paints. In contrast, monostyrene is significant as copolymerisation partner for paint binders, such as acryl resins, dispersions, styrene-containing alkyd resins and unsaturated polyester resins. In the processing of polyester resins and polyester paints, the paint manufacturers have to handle monostyrene; hence they should be aware of the reactivity, sensitivity and physiological activity of monostyrene. These aspects are dealt with too.     

Electric conductivity measurements in water dispersion paints for mechanistic studies of reflection properties formation during surface painting and paint film drying

Electric conductivity measurements of water dispersion paints were carried out in order to understand the mechanism of film formation and drying and the formation of painted surface reflection properties. The classical model of electric conductivity in viscous media based on a comparison of the Coulomb and Stokes formulas was used to determine the effective mechanism of the paint properties. This model was verified by measurements in the paint bulk. The classical concept of the electric conductivity of viscous liquids was found to be applicable to the conductivity analysis of the studied water dispersion paint specimens. The electric conductivity of the studied paints was found to be determined by the existing admixtures being soluble in water and/or dispersion organic particles. The formulated method for dynamic conductivity measurements of paint film thickness assumed a constant temperature and viscosity. Strong electrostatic phenomena were detected at the initial stage of paint aerosol deposition, while a compact film has not been formed yet. The film conductivity measuring experiments found that the film drying process consists of two stages. At the first stage, conductivity is sharply decreasing and the paint film reflectivity is sharply increasing. At the second stage, evaporation is delayed. It is limited by the diffusion transfer of volatile components from the film bulk and from the paint dispersion particles. Here, a slow growth of the reflectivity and a decelerating decrease in the conductivity is observed. A qualitative mathematical dynamic model was developed for the paint film reflectivity due to the orientation of pigment particles, and the calculations showed that the first stage of drying is the most important for the orientation.     

乳胶漆色彩均一性控制

文章讨论了影响乳胶漆色彩均一性的因素,主要有亲水亲油平衡值（HLB）、基础漆与水性色浆的相容性、表面张力差、颜填料粒径分布等,指出了彩色乳胶漆调制和施工中出现浮色发花现象的方法,提出了控制乳胶漆色彩均一性的解决方案,不仅保证乳胶漆静态贮存时色彩均一,更要保证涂膜于燥成膜后色彩均一,对乳胶漆色漆的调制生产和施工都有积极的指导意义。     

Influence of coating system composition on moisture dynamic performance of coated wood

Model coatings with known composition were assessed for liquid water permeability both as single coat systems and combined as primers and topcoats to form regularly used coating systems—in total 38 different systems. The water permeability of the coatings, expressed as water absorption value, was measured by a method similar to the method that now is proposed as a European standard for the assessment of liquid water permeability. During artificial weathering, the samples were measured for a water absorption value, thus showing the change in water permeability as a function of weathering. The study has shown that an excess of surfactants in the alkyd emulsions has a negative effect on the coating’s ability to exclude water from the test samples. A waterborne acrylic paint based on a dispersion of larger particle size (0.4 μm) showed a poor ability to exclude water compared to a similar paint based on smaller dispersion particles (0.1 μm). The alkyd emulsion paints, as single coats, showed high water absorption values compared to solventborne paints and acrylic paints. P.O. Box 5609, SE 114 86 Stockholm, Sweden     

常温固化氟碳涂料的研究

以三氟氯乙烯-乙烯基化合物共聚物（亦称FEVE树脂）为基料,异氰酸酯HDI三聚体为固化剂制成常温固化型双组分氟碳涂料。该涂料具有一般氟树脂涂料的超长耐候性和耐温性、优良的耐化学介质腐蚀性、卓越的防污染、良好的机械性能以及品位典雅的装饰性能,同时具有一般涂料的溶解性、可常温固化性等。分析讨论了树脂的氟含量、主要助剂、固化剂、溶剂的选用对涂料主要性能的影响。     

The influence of binder content on the water transport properties of waterborne acrylic paints

Diffusion coefficients and sorption isotherms of water in waterborne acrylic paint films and in the pure binder of the paints have been measured by gravimetric sorption. Solubility of water was found to enhance with the increased binder content in the paint films while the diffusivity of water decreased significantly. Sorption isotherms in the paint and pure copolymer films were correlated with the Flory Huggins theory and ENSIC model, respectively. Fickian diffusion was observed in both types of films and the kinetic data were best correlated with a numerical model which takes into account the concentration dependency of the diffusion coefficient and the dimensional change of the film due to sorption. It was concluded that the utilization of a simplified analytical solution may lead to significant errors in the estimation of diffusivities.     

Associative polymer/particle dispersion phase diagrams III: Pigments

The colloidal interactions of both HEUR and HASE associative polymers with pigments in the presence of dispersant are complicated and subject to a number of variables. The objective of this work was to clarify the conditions needed to achieve good pigment dispersion in associative thickener systems by characterizing particle dispersion behavior. This had previously been done for latex particles, but not for pigments such as TiO₂. Good dispersion leads to optical properties, such as gloss and hiding, that are superior to nonassociative thicknener systems. Pigment dispersion phase diagrams represent a good way to visualize the complex interactions among pigments, dispersant, and thickener. The two most important variables were found to be pigment type (i.e., surface composition) and dispersant composition. Associative thickners can yield good pigment dispersion or flocculation, depending on the correct matching of dispersants and pigment type. Because of the hydrophobic functional groups governing associative thickner behavior, dispersants having some hydrophobic character yielded the best pigment dipersions and optical properties because they could couple the pigment particles with the associative thickener network. Interior-grade TiO₂ tended to yield better dispersions and optical properties than exterior-grade TiO₂. Optimized associative thickner systems generally had improved optical properties over comparable nonassociative systems. Optical properties correlated well with particle dispersion behavior as displayed by the dispersion phase diagrams. Presented at the Tess Symposium of the 230th American Chemical Society National Meeting, Aug. 28–Sept. 1, 2005, in Washington, D.C.     

Development of hybrid antifouling paints

The objectives of this study are to measure the efficiency of a hybrid system for antifouling paint and to observe the influence of the physico-chemical properties of the binder on the antifouling activity. Poly(ɛ-caprolactone) (PCL) and poly(dimethylsiloxane) (PDMS) homopolymers are already used as binder for different antifouling strategies. The use of the block copolymer should allow to mix the properties of erosion and hydrophobicity to obtain a more efficient paint with a reduced environmental impact.Paints containing triblock copolymer were immersed in seawater in Lorient harbour to evaluate their antifouling activities. The water absorption, the degradation and the surface properties of the copolymer were measured in distilled water to understand the influence of the binder characteristics in the resulting antifouling properties.The hybrid paints have shown efficiency close to a commercial paint during their immersion in situ in spite of inadequate static conditions of test.     

Drying and collapse of hollow latex

Hollow latex particles are used as white pigments for paints and paper coatings. In the coating dispersion, each hollow particle is filled with water. As the coating dries, water vacates the latex, leaving an air-filled void sized to scatter light (~0.5 μm) within each particle. Examinations of dried coatings reveal that hollow particles can collapse, decreasing their light scattering efficiency. Cryogenic scanning electron microscopy (cryoSEM) was used to characterize the microstructure of coatings containing hollow latex during drying. Images suggest latex voids empty after air invades into the coating interstitial space and collapse occurs late in the drying process. The effects of temperature (10–60°C), humidity (20–80%), and binder concentration (0–30 wt%) on particle collapse were also studied through SEM of dried coating surfaces. High drying temperature, high humidity, and low binder concentrations promoted collapse. For hollow latex particles with porous shell walls, temperature and humidity had little effect, whereas binder increased collapse. From these results, a theoretical model is proposed. During drying, diffusion of water from the particle creates a vacuum inside the latex. The vacuum is either relieved by nucleation of a gas bubble from the dissolved air in the water-filled particle or it causes the particle to collapse by buckling.     

Application of microcalorimetry to the study of interactions in coating formulations

Water-based coating formulations contain many components, such as latex binder, pigment, dispersant, thickener, and surfactant. Complex interactions between these components affect properties of the coating in both the wet and dried states. For example, rheology of the paint is dependent on the interactions of components in the formulation. Pigment interaction can affect the degree of dispersion and, therefore, have ramifications on end use properties such as hiding and tint strength of the paint film. Isothermal titration calorimetry has been used to determine the enthalpy of interaction of the coating components. Representative examples will be given to demonstrate structure–property relationships that correlate the interactions of latex, pigment, surfactant, dispersant, and thickener with paint viscosity as well as end use performance parameters such as adhesion and tint strength.     

Development of heat-resistant anticorrosion urethane siloxane paints

Three two-layer heat-resistant and anticorrosion paints have been formulated from urethane siloxane binder and traditional anticorrosion pigments such as micaceous iron oxide (MIO), zinc phosphate (ZP), and aluminum oxide. These pigments were used as the dominant components of different undercoats or topcoats. Heat-resistant pigments such as silicon nitride and glass-spheres were used in the composition of the topcoats. Thermogravimetric analysis of paints shows that the paint with ZP as dominant component of the undercoat have the highest heat-resistance and stability in inert gas and oxygen. The paint with a combination of MIO and ZP has the best hardness as well as the best protective and anticorrosion properties based on the electrochemical impedance spectroscopy. A maximum synergic effect of the properties of pigments seems to appear in this paint. Surface morphology of paints was studied by means of scanning electron microscopy. Heated at different temperatures and for several hours, paint containing MIO as the dominant component in the undercoat exhibits the best mechanical and adhesion properties.