Effect of precipitated calcium carbonate additions on waterborne paints at different pigment volume concentrations

Titanium dioxide (TiO₂) due to its high refractive index, is widely used in paint industry as a white pigment. In order to reduce this high cost of TiO₂, a part of TiO₂ is generally substituted by some other industrial mineral fillers such as calcite and calcined kaolin; however, this substitution affects the quality of paints in terms of stability, coverage (opacity), brightness (gloss), scrub resistance (film toughness), etc. In the present paper, precipitated calcium carbonate (PCC) was substituted for TiO₂ in paint mixture at three different pigment volume concentrations (PVC). It was observed that substitution of TiO₂ by PCC depends on PVC value at which there is an optimum PCC amount. The quality of paints produced by PCC along with its rheological properties was evaluated based on standard features in both wet and dry paints such as viscosity, density, opacity and gloss values. Addition of PCC increases the opacity to a certain point. Similarly, scrub resistance and viscosity increases with the addition of PCC at all PVCs, however, viscosity is not as much critical for the paint production. On the other hand, there is no any systematic effect of PCC on gloss value of the paint. This study overall demonstrates that PCC can be successfully used to substitute TiO₂ only with a careful adjustment of PVC and other extenders used in the paint formulation.     

Glossy topcoat exterior paint formulations using water-based polyurethane/acrylic hybrid binders

The development of glossy topcoat one-pot exterior paint formulations using water-based polyurethane/acrylates hybrid binders as well as the assessment of its properties through different conventional tests is discussed in this work. Polyurethane (PU) anionomer having 2-ethoxymethacrylate terminal groups was prepared following a prepolymer mixing process. This prepolymer was chain extended in aqueous solution and after addition of acrylic monomers radical polymerized. Paints were prepared using titanium dioxide as unique pigment. Panels coated with air-dried paints with three pigment to volume concentration (PVC) values were subjected to standardized tests including adhesion, flexibility, gloss and color determination. Accelerated weathering tests were carried out to evaluate changes in properties, especially gloss and color, of painted panels. Solvent-based acrylic and polyurethane paints were included as high gloss quality reference coatings. It was found that air-dried formulations based on hybrid polyurethane/acrylic with up to 50 wt.% of acrylic component, show a gloss as high as 70 and the relative gloss change after accelerated weathering test is lower than the pure solvent-based acrylic and polyurethane paints.     

Latex particle size and CPVC

Monodisperse vinyl acetate/butyl acrylate (85/15) latexes were prepared with particle sizes between 200 and 1200 nm. These were used in a simple paint formulation with TiO₂ as the only pigment. Two optical methods were used for determination of the critical pigment volume concentration (CPVC) of these paints. These are specular gloss at an incidence angle of 85 ° and CIE Z (lightness) values of a blue tinted formulation. Both methods gave coincident results for the CPVC as a function of latex particle size. Our data fit the expression X = 1.44Y^2.65 where X = number of latex particles/number of pigment particles, at CPVC and Y = diameter of pigment particles/diameter of latex particles. Earlier, Bowell reported the same exponential relation, with a different pre-exponential factor, for acrylic latexes. The common exponent is explained with a model in which the latex and pigment particles assume a condition close to minimum porosity during packing. CPVC reflects the packing of particles during the initial stages of dryness of the latex. The ‘universal’ relation reported here permits facile prediction of the effects of latex particle size on the CPVC and binding capacity in water-based paints.     

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.     

Titania pigment particles dispersion in water-based paint films

The distribution of titanian pigment, in dry water-based paint films in the presence of polymeric dispeersants containing different functional groups was investigated. The polymeric dispersants chosen were polyacrylic acid and polyacrylamide momo-and copolymers modified with hydroxyl and/or carboxylate groups. Atomic force microscopy (AFM) and transmission electron microscopy (TEM) were used to assess the distribution of the titania pigment particles in the surface and bulk, respectively, of the paint films, which was then compared to the gloss and surface roughnes of these films. In the absence of dispersant, the pigment distribution in the paint film was not uniform and relatively large pigment aggregates appeared at the surface, resulting in a rough surface and low gloss value. All dispersants both decreased surface roughness and increased the gloss of the dry paint film, with the dispersant type considerably enhancing the pigment dispersion in the dry paint film, in agreement with results obtained in aqueous pigment suspensions. In the presence of polyacrylamide homopolymer, the paint gloss increased slightly and further increased with the hydroxyl-modified polyacrylamide copolymer. The paint gloss was highest in the presence of polyacrylic acid or carboxylate/hydroxyl-modified polyacrylamide.     

The pigmentation of powder coatings with the use of block copolymer dispersants

The dispersing of pigments in powder coatings is a difficult and complicated process. The incomplete dispersion under standard extrusion conditions can be attributed to a combination of poor pigment wetting and insufficient disruption of the pigment agglomerates, as a result of the rheological properties of the powder coating resin. The use of block copolymer dispersants for improving the pigment dispersion in powder coatings is studied in this project. Novel block copolymer dispersants from 2-vinylpyridine and ε-caprolactone have been synthesized and tested. These block copolymers show a high affinity for TiO₂ pigments and are capable of improving the stability of a TiO₂ dispersion in a polyester powder coating resin.     

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.     

Evaluation of Mesua ferrea L. seed oil modified polyurethane paints

Two types of stoving paints have been prepared from Mesua ferrea L. seed oil (MFLSO) modified poly(urethane ester) (PUE) binder systems. One stoving paint system was prepared from partially butylated melamine formaldehyde (MF) resin modified MFLSO-based PUE (70:30 weight ratio) and other one comprised of bisphenol-A-based epoxy resin modified with MFLSO-based PUE (50:50 weight ratio). Paints made with these two resin systems as binders were evaluated against the standard paint system. The physical properties of the paint systems viz. non-volatile content, specific gravity, viscosity, drying time, flexibility, adhesion, scratch hardness, gloss, etc. and chemical properties such as corrosion resistance, salt spray resistance, UV resistance, etc. were measured as per the standard methods and were compared. Thermal stability and surface morphology of the paints were also studied by using thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. The performance characteristics of both the test paints were found to be comparable with the corresponding industrial standard paints. Out of the two test paints, the epoxy modified PUE-based stoving paint has been found to be preferred.     

High-build soluble matrix antifouling paints based on vinyl resin

The aim of this work was to formulate and evaluate high-build, soluble matrix antifouling paints showing reduced solvent retention in the film and sufficient bioactivity to protect structures submerged in sea water for long immersion periods.

The variables analyzed were binder composition, pigment content, toxicant type and thixotropic agent content.

Binder dissolution in sea water was achieved by employing WW rosin or calcium resinate; the control of the binder dissolution rate was achieved by using a vinyl resin as a cobinder. The paints were formulated with pigment volume concentrations of 40 and 45%; red cuprous oxide and triphenyl tin fluoride were used as the main toxicants. The rheological additive employed was hydrogenated castor oil at levels of 2.0 and 2.5 wt.% in the paint.

The bioactivity of the antifouling paints was determined in the natural environment (30 month immersion in sea water).     

Fate of a coalescing aid after latex paint application

Water-based coatings require coalescing aids to achieve properties equivalent to solvent-borne paints. A common coalescing aid in latex paints is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TMPD-MIB). The relatively large quantity of TMPD-MIB used in latex paints has raised concerns regarding its emissions to both indoor and outdoor atmospheres. In this study, a one-dimensional dual (paint and material) layer diffusion model was developed to estimate emissions of TMPD-MIB from two latex paints applied to gypsum board. The paints contained different pigment volume concentrations (PVC) and different amounts of TMPD-MIB. Different modeling approaches were used depending on the PVC of the paint. The proposed model for paint drying and TMPD-MIB emissions was tested with data from previous chamber experiments. Experimental data were first used for purposes of parameter estimation, and the model was then compared against an independent experimental dataset. The diffusion coefficient of the paint layer was adjusted as a function of the water content remaining in the wet paint film. The effective diffusion coefficient of TMPD-MIB in the paint layer was found to be dependent on the PVC and water content of the paint.     

双组分水性聚氨酯涂料的制备与性能测试

选用水性羟基丙烯酸分散体为成膜物质,水可分散型异氰酸酯（HDI三聚体）为固化剂,以钛白粉为颜料,搭配合适的助剂,制备了干燥快、光泽高、耐候性优异及低成本的双组分水性聚氨酯涂料。考察了颜基比、固化剂的量对涂膜性能的影响,通过涂料体系颜料体积浓度的计算,推导出PVC的倒数与P/B的倒数呈一次线性函数关系。     

Influence of nonionic emulsifiers on the properties of vinyl acetate/VeoVa10 and vinyl acetate/ethylene emulsions and paints

This paper presents results on the influence of the nonionic surfactant on the properties of vinyl acetate/VeoVa10^® and vinyl acetate/ethylene emulsions and paints made thereof. Emulsions were prepared in which the concentration of the nonionic surfactant and its degree of ethoxylation were varied. An increase of the nonionic emulsifier concentration and of the length of the ethylene oxide chain leads to dispersions with smaller particles and higher viscosities. Using these emulsions as binders in high pigmented paints, it was observed that the pigment binding capacity of the interior paints goes through a maximum which is located at a emulsifier concentration of about 2–3% and at a degree of ethoxylation of 17–28 mol ethylene oxide (EO). In (semi-) gloss paints, the gloss of the paint films improves with an increase of the emulsifier concentration and reaches a constant value at around 4% or a degree of ethoxylation of ca. 17 EO-moieties per molecule. The blocking of the films shows a drastic increase at a concentration above 4% and at a chain length of greater than 17 EO-moieties.     

浅谈高光柳编面漆的制备

主要从PVC、基料、颜料、润湿分散剂、消泡剂、成膜助剂、增稠剂等方面分析了制备高光柳编面漆的注意事项。     

Synthesis of functionalized mesoporous TiO2 molecular sieves and their application in photocatalysis

Functionalized mesoporous TiO₂ molecular sieves were prepared by treating ordered mesoporous TiO₂ with phosphoric acid or ammonium sulfate at high temperature. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption–desorption measurement, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectrometer (FT-IR). The photocatalytic activity of the samples was evaluated by photocatalytic decomposition of bromomethane (CH₃Br) in air. Results revealed that the functionalized TiO₂ samples preserved ordered mesostructure and exhibited enhanced physicochemical properties. The photocatalytic activity of the functionalized mesoporous TiO₂ sample was about three times higher than that of the pure mesoporous TiO₂. The concentrations of phosphoric acid and ammonium sulfate solutions used for the functionalization of TiO₂ greatly influenced the photocatalytic activity of the resultants materials. The optimal concentrations of phosphoric acid and ammonium sulfate solutions were 0.05 and 0.10 M, respectively. The enhanced photocatalytic performance of the functionalized mesoporous TiO₂ could be attributed to large specific surface area, high hydroxyl density, and enhanced surface chemical state.     

石墨烯/二氧化钛对PVC薄膜性能影响

以石墨粉和三氯化钛为原料,通过Hummers和水解法制备得石墨烯/二氧化钛(G/TiO2),将G/TiO2作为填料添加到聚氯乙烯(PVC)中,探究其对PVC薄膜性能的影响.结果表明,添加G/TiO2提高了PVC薄膜的力学性能、抗静电性能和耐紫外老化性能.添加G/TiO2的PVC薄膜的拉伸强度由纯PVC薄膜的12.79 ...     

The preparation of coupled WO3/TiO2 photocatalyst by ball milling

The coupled photocatalyst WO₃/TiO₂ is prepared by ball milling by doping WO₃ into TiO₂ and using H₂O solution as disperser. The coupled photocatalyst WO₃/TiO₂ is characterized by UV–VIS diffuse reflection spectrum, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and Transmission electron microscopy (TEM). The results show that the optimum percentage of WO₃ doped is 3% and that the photocatalytic activity of the coupled WO₃/TiO₂ photocatalyst is much higher than that of TiO₂ and WO₃–TiO₂ with no ball milling. Compared with TiO₂, the photoexcited wavelength range of the WO₃/TiO₂ photocatalyst red-shifts about 50 nm, and the light absorption intensity is also improved. The crystal phase of TiO₂ is not changed and new crystal phases are not found during the process of ball milling. WO₃ and TiO₂ coupled highly, forming the WO₃/TiO₂ photocatalyst. The increased photocatalytic activity of the coupled photocatalyst may be attributed to the enhance charge separation efficiency and the extend wavelength range of photoexcitation.     

基料和颜料对乳胶漆光泽的影响

研究了建筑涂料中常用的相同基料、不同颜料,及相同颜料、不同基料时,漆膜光泽随颜料体积浓度（ＰＶＣ）变化的关系。随着ＰＶＣ的增加,漆膜光泽逐渐减弱,但不同的基料及颜料对漆膜光泽的变化影响程度不同。主要探讨了漆膜光泽与基料颜料的折射率、密度、粒径的关系。漆膜的光泽随着基料和颜料折射率的增大、粒径的减小而增大;随着颜料密度增加、颜料分散性降低而减弱。     

Optimization of the water-based road-marking paint by experimental design, mixture method

The main purpose of this research is formulating and optimizing a new road-marking paint which is an environmentally friendly product. This paint is produced with an emulsion of an acrylic copolymer and contains the least of the volatile organic compounds. The formulation and optimization procedure is carried out on the base of experimental design by the method of mixture in which the important paint properties are modeled by using special cubic model. The present method has the capability of investigation the effect of raw materials at different levels with fewer experiments than factorial and fractional factorial design.

In this research, the main parameters such as resin, pigment and filler were selected at different levels, and different samples were prepared by combination of additives and other required reagents. The properties of wet and dry films of the samples were determined using ASTM test methods. Different responses such as pigment volume concentration (PVC), latex critical pigment volume concentration (LCPVC), abrasion resistance, hardness, gloss, no pick up time and surface drying time, were selected as the objective functions of this study. By running DX6 software, using special cubic model and selection of desired range of end-use properties, the region of optimum paint formula was determined.

The accuracy of the model was examined by preparing a sample in optimized region and by determining its final properties, experimentally. The results exhibit a good agreement between the model and experimental measurements. This product was compared with commercial solvent based traffic paint and good quality was reported in end-use properties.     

Thixotropic properties of yellow iron oxide-alkyd paints: their dependence on pigment-resin-solvent interactions

The effect of pigment content and the nature of the solvent on the thixotropic properties of synthetic yellow iron oxide in alkyd paints have been studied by viscometry. The degree of thixotropy of a paint has been calculated from the area of the thixotropic loop. The thixotropic effect in these paints is found to appear at about 35% PVC content and increases with the level of pigmentation up to 55 to 60% PVC content. The degree of thixotropy of paints also depends on the nature of the solvents used in the formulation. Interactions between pigment and solvent and between alkyd and solvent help in building structure and consequently in developing thixotropy in yellow iron oxide-alkyd paints. The shear dependence has been analysed using the Power law and the Casson equation.These paints exhibit only pseudoplastic flow behaviour and their consistency index depends on the pigmentation level and the solubility parameter of the solvent. Sag resistance depends on the PVC content and the nature of the solvent, but the brushability property is independent of these parameters.     

冬瓜基含TiO2炭气凝胶的制备、表征及其光催化性能

以冬瓜和钛酸四丁酯为原料,采用水热法和冷冻干燥法成功制备出含TiO₂炭气凝胶（WTCA）,研究了其对罗丹明B废水的光催化降解性能,并考察了水中常见无机盐离子对其光催化效果的影响。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、拉曼光谱仪（Raman）和荧光光谱仪（FL）等对样品结构和性能进行了表征。XRD、Raman和EDS分析表明复合气凝胶中含有锐钛矿TiO₂和碳元素;SEM和TEM分析表明TiO₂纳米颗粒均匀地负载在具有多级孔洞结构的炭气凝胶的骨架表面;含TiO₂炭气凝胶的光催化活性明显高于纯TiO₂,当负载量达30%时,其对罗丹明B的光催化降解效率最高（降解率达96.11%）。此外,无机盐阴离子对复合气凝胶的光催化效果有一定的抑制作用（CO₃^2- > SO₄^2- > Cl^- > NO₃^-）,而无机盐阳离子Na⁺、K⁺、Ca²⁺和Mg²⁺的抑制作用不明显。