Low Gloss Research Articles

Optimum Analysis of Microporous Foaming/Mould Decoration Compound Forming Technology for Automobile Door Decoration Panel

All Energy conservation and environmental protection are increasingly concerned by the automotive industry. Lightweight vehicles are one of the effective ways to achieve energy conservation and environmental protection. As an important method in plastic processing, the microcellular foam injection molding process can further meet the requirements of lightweight vehicles while meeting the performance requirements of the parts. However, a large number of bubbles exist on the surface of the microcellular foamed injection molded product, and the problems such as large surface roughness, low gloss, and poor apparent quality restrict the application of the process in automotive plastic parts. In order to improve the surface defects of microcellular foamed parts, this paper establishes experimental schemes and mathematical models based on partial factor test design method, response surface design and genetic algorithm, and obtains the optimal micro-foaming/in-mold decorative composite injection molding. Process parameter plan.

Low gloss waterborne polyurethane coatings with anti-dripping and flame retardancy via montmorillonite nanosheets

A series of low gloss organic montmorillonite/waterborne polyurethane nanocomposite (OWPU) coatings with polycaprolactone (PCL) and hydroxyl terminated polybutadiene (HTPB) were prepared, characterized and then applied to polyvinyl chloride leather. Small-angle XRD and TEM examinations indicated that montmorillonite was exfoliated into individual single-layer nanosheets in HTPB, and retained separate shapes in subsequent synthesis and preparation. The OWPU dispersions with higher nanosheets contents exhibited a larger average particle size and a less negative zeta potential obtained through DLS. A rougher coating surface topography of OWPU compared with pristine WPU was observed by SEM, which reduced the 60° gloss to 4.6 GU within the matt range. Moreover, TGA results indicated that the nanosheets effectively increased thermal stability of hard segments and soft segments derived from PCL, but had little effect on that of soft segments derived from HTPB. Furthermore, rheological analysis confirmed the nanosheets promoted cross-linking and cyclization of HTPB at high temperature, thereby imparting anti-dripping properties to OWPU coatings. Cone calorimeter test and SEM results showed that flame retardancy of OWPU was improved by forming a charred layer with sheet-cluster structure. In addition, incorporation of the nanosheets was also capable of changing the surface touch feeling of OWPU coatings from sticky to some dry alike.

Temperature and concentration control of exothermic chemical processes in continuous stirred tank reactors

Exothermic chemical reaction taking place in continuous stirred tank reactor is considered. Heat release from the chemical reaction, non-linear dynamic behavior of the process and uncertainty in parameters are the main factors motivating the use of robust control design. Viewing temperature and molar concentration as variables both accessible in real time, PI and optimal state-feedback controllers driven by temperature and concentration error signals are proposed to regulate the system over reactor’s steady-state working points by counteracting undesired disturbances. Since access to concentration value has proved beneficial for the reactor’s performance, estimation techniques are examined to compensate for the problematic nature of the concentration’s measurement. A linear reduced-order observer is first proposed to estimate the concentration value using temperature measurements. In addition, assuming concentration measurement is available with a relatively short delay via sample analysis, a linear and non-linear discrete-time predictor is constructed to estimate the concentration’s real-time value. A linear combination of the two estimation schemes (observer, predictor) is proposed resulting in a combined estimator, in which the emphasis between the two individual schemes can be controlled via a scalar parameter. The work presented in this paper was supported by the GLOW project – New weather-stable low gloss powder coatings based on bifunctional acrylic solid resins and nanoadditives – as part of the development of novel and efficient processing technologies regarding the production of new families of powder coatings, responding to industrial requirements for quality improvement at lower cost and shorter development cycles.

Optimization of Process Parameters for Anti-Glare Spray Coating by Pressure-Feed Type Automatic Air Spray Gun Using Response Surface Methodology.

The process of preparing anti-glare thin films by spray-coating silica sol-gel to soda-lime glass was exclusively and statistically studied in this paper. The effects of sol-gel deliver pressure, air transport pressure, and spray gun displacement speed on the gloss, haze, arithmetic mean surface roughness, and total transmittance light were analyzed. The experimental results indicate that the factors of sol-gel deliver pressure, air transport pressure, and displacement speed exhibit a significant effect on the haze, gloss, and Ra. In contrast, the variation of total transmittance light with these three factors are insignificant. Because the anti-glare property is predominantly determined by low gloss and high haze, we therefore aim to minimize gloss and maximize haze to achieve high anti-glare. Central composite design and response surface methodology are employed to analyze the main and interaction effects of the three factors through quadratic polynomial equations, which are confirmed by the analysis of variance and R2. The response surface methodology predict the lowest gloss and highest haze are 9.2 GU and 57.0%, corresponding to the sol-gel deliver pressure, air-transport pressure, and displacement speed of 250 kPa, 560 kPa, and 140 mm/s, and 340 kPa, 620 kPa, and 20 mm/s, respectively. Comparing the predicted optimal data with the real experimental results validates the applicability of the mathematical model. This study provides an important basis for the subsequent production of anti-glare glass with different specifications to satisfy the market demand.

Synthesis of an Aqueous Self-Matting Acrylic Resin with Low Gloss and High Transparency via Controlling Surface Morphology.

This paper reports on a novel, film-forming acrylic polymer resin that exhibits low-gloss surface and high transparency via controlling film morphology at sub-micron roughness levels. Such microstructure is controlled by means of the copolymerization process increasing the allyl methacrylate (AMA) crosslinker content from 0 to 0.4 wt %. This acrylic resin makes it possible to avoid high loadings of matting agents, while also having good abrasion resistance and soft-touch feeling. Gloss levels of as low as 4 units at 60° incident angle and light transmittance of up to 85% have been achieved. The chemical structure of the aqueous acrylic resin was characterized by ATR-FTIR and NMR spectroscopy. The film morphology and surface roughness were measured by SEM and AFM analysis. The emulsion particle morphology and glass transition temperature were obtained by TEM and DSC, respectively. The effects of the crosslinker content on the light transmittance, glass transition temperature, and thermal degradation stability were also discussed in detail. The characterization results conclude that an acrylic polymer with interesting optical properties and high thermal stability can be obtained, which is desirable for leather applications.

Scanning of skin gloss by a diffractive optical element-based handheld glossmeter

Skin specular gloss (referred to as “gloss’’) determination is important in dermatology and cosmetic industry as it gives an indication of the skin health and beauty. Its accurate determination is, therefore, necessary. Commercially available glossmeters typically employ large incidence angle geometry, large illumination area, and fixed point measurements making them impractical regarding measurement of curved and complex non-planar objects or surfaces as well as low gloss regime such as the skin. In this study, we have demonstrated the novel application of a diffractive optical element-based handheld glossmeter with scanning capability, overcoming the disadvantages of conventional glossmeters, in the accurate determination of skin gloss and gloss profile for different skin types under different measurement conditions. Different parts of the body (back of the hands, the inner part of the arm and the forehead) of four volunteers with light, dark and intermediate skin types were scanned (also in different directions) to obtain the skin gloss profile and the statistical average skin gloss. Additionally, the skin surface was modified by arm extension and scanned as well. Our preliminary results showed that the statistical average skin gloss reading increased with the increasing lightness of skin. Areas with higher sebaceous glands (forehead) showed higher gloss reading than the other body parts (inner arm and back of the hand). However, the roughness of the skin surface decreased the statistical average skin gloss reading. The handheld scanning skin glossmeter allows for the accurate determination of skin gloss with sensitivity to small variation in the skin surface roughness with high repeatability.

Hybrids of CNTs and acrylic emulsion for the consolidation of wall paintings

Acrylic resin Primal® AC 33 is a common consolidant for wall paintings in a large scale. However, some disadvantages are encountered, such as low glass transition temperature (Tg), unwanted hygroscopicity, and surface gloss when applying it on wall paintings. To address these issues, the hybrids of the gum arabic treated single-walled carbon nanotubes (SWCNTs) and the Primal® AC 33 were prepared with a different weight fraction of SWCNTs ranging from 0.005% to 0.05% via solution blending. The morphology, chemical, thermal, mechanical, and optical properties of the hybrids were systematically investigated by various characterization methods. The results show that the Tg, the hardness, and the adhesion of the hybrid films are increased with the presence of SWCNTs, while the transparency and the gloss value of the films in the visible light range decrease simultaneously compared with the pristine AC 33 film. When the hybrid solutions were applied on simulating wall painting plaster samples, the evaluation data suggest that the hybrids with the SWCNT concentration not exceeding 0.025 wt% in AC 33 can be potentially used in the consolidation of the surface layer of wall paintings. The hybrids with a higher SWCNT concentration play a positive role in the consolidation of the ground layer of wall paintings. Our work opens a new insight for enhancing the properties of a consolidant for wall paintings by introducing SWCNTs.

Preparation and characterization of a novel low gloss waterborne polyurethane resin

A novel waterborne polyurethane (WPU) resin with low gloss and micro-roughness was synthesized by the prepolymer and self-emulsification method. It was achieved by introducing multi-hydroxyl castor oil and reactive bisphenol A-type epoxy E-44 or E-51 resin to polyurethane prepolymer to form a cross-linking network structural waterborne polyurethane emulsion, which demonstrated the distinctive characteristic of the shear-thinning pseudoplastic fluid with a yield stress. The chemical structures and rough surface morphologies of the WPU films were characterized by FTIR-ATR, LCRS, AFM, SPMS and SEM, respectively. The specular gloss values at 20°, 60° and 85° incident angles were measured, and the values of different kinds of roughness parameters were obtained. The relationship between the gloss and the castor oil content was also discussed in detail. In general, this WPU resin endowed the film with micro-roughness, moderate hardness and good adhesive strength, making it very prospective in substitution for the traditional low gloss coatings.

Structure and surface properties of a novel bulk-matte waterborne polyurethane coating composite

This paper reports on a novel self-matte or bulk-matte waterborne polyurethane coating composite with inherently extremely low gloss. The coating composite was comprised of a siloxane-containing waterborne polyurethane (SPU) resin and a crosslinked waterborne polyurethane (CPU) resin. The CPU resin was mainly responsible for fabricating the micro-rough surface of the film, which was achieved by a crosslinking reaction between the waterborne polyurethane and bisphenol A-type epoxy E-44 resin. The SPU resin was used to improve the comprehensive properties of the film, which was ascribed to the addition of silane coupling agent KH792. Compared with traditional matte coatings, this coating composite made it possible to avoid high loadings of matting agent and to arrive at highly flexible low-gloss finishes. Gloss levels of as low as a few tenths of a percent, even at high incidence angles, have been achieved with zero loading of extraneous dulling agent. The chemical structures of the SPU and CPU resins were characterized by FTIR-ATR and NMR spectra. The micro-rough topographies and surface rough degrees of the SPU, CPU and their 50%/50% composite films were measured by SEM and MSP, respectively. The particle sizes and particle morphologies of the SPU and CPU resins were imaged by TEM. Finally, the comprehensive properties of the SPU, CPU and their 50%/50% composite resins were evaluated, including the water contact angle, film transparency, tensile strength and storage stability.

Preparation and characterization of low gloss aqueous coating via forming self-roughed surface based on waterborne polyurethane acrylate hybrid emulsion

Abstract A series of low gloss waterborne polyurethane acrylate (WPUA) hybrid emulsions with different weight ratios of hard/soft monomers of acrylic monomers were synthesized successfully. Compared with the traditional low gloss coatings that achieve low gloss effects by adding a large number of pigments, fillers or both to roughen the surfaces, the low gloss effect of these WPUA emulsions was achieved through the formation of self-roughed surfaces during film formation with zero loading of extraneous dulling agent. Gloss levels could be as low as 3 units at 60° incident angle. The chemical structures of these WPUA films were characterized by nuclear magnetic resonance carbon spectroscopy ( 13 C NMR), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The rough surface topographies of these WPUA films were observed by scanning electron microscopy (SEM). The particle size distributions of these WPUA emulsions were analyzed by DLS measurement. The polymeric phase separation behaviors of these WPUA films were assessed by DSC analysis. In general, the WPUA emulsions that afforded films with good hardness, good adhesion strengths and excellent thermal stabilities, showed a great advantage in applications of low gloss aqueous coating.

Alternating Current Phosphoric Acid Etching of Aluminium

Alkaline etching is a common pretreatment process for aluminium alloys before anodising or application of organic coating. Removal of the mill-finish surface layer is performed by a simple dipping process, which also gives the matt finish normally required for aesthetic appearance before conventional anodising. Major disadvantage of alkaline treatment is the surface enrichment of the alloying and trace elements more noble than the aluminium substrate by dealloying. This may reduce corrosion resistance and deteriorate the optical properties of the surface. The purpose of this work is to investigate fluoride-free acid etching for aluminium alloys as an alternative to alkaline etching to prevent or reduce heavy metal enrichment, while achieving matt appearance. Alternating current is applied to increase the rate of etching as the dissolution rate of aluminium in acid solutions is slower than in alkaline solutions. The principle is based on anodic oxidation of the heavy metal components, as well as aluminium, during the anodic cycle and removal of the corrosion products and concentration gradients by hydrogen evolution during the cathodic cycle. The materials used for this study were hot-rolled aluminium alloy AA3105 (Si 0.3%, Fe 0.6%, Cu 0.1%, Mn 0.7%, Mg 0.3%) and extrusion AA6060 (Si 0.4%, Fe 0.2%, Cu 0.01%, Mn 0.02%, Mg 0.5%). Phosphoric acid was used as the etching electrolyte. Consumption of aluminium was calculated from weight loss. Appearance was analysed visually and by gloss measurements. SEM was used to study surface microstructure and morphology. Aluminium oxidation rate increased with increasing temperature, current density, electrolyte concentration and etching time. Intermetallic Al-Mn-Fe-Si particles were selectively and rapidly removed by 1 min etching at 80⁰C. In contrast, particles were exposed and remained on the surface by alkaline etching. Matt appearance without visible defects was achieved after 10 min etching at 80⁰C. Presence of phosphorus in thin oxide film formed was determined by glow discharge optical emission spectroscopy (GD-OES). Advantages foreseen of acid-based AC pretreatment over alkaline dip processes in practice are suitability for in-line coil processing, superfluity of the desmutting step, low gloss achievable with reduced metal loss, improved corrosion resistance and adhesion properties. Acknowledgements This work was supported by Hydro Aluminium and The Research Council of Norway.

High sensitivity optical measurement of skin gloss.

We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents.

A novel contribution to the modeling of the matting efficiency of aqueous polyurethane dispersions

Gloss is a critical issue in many applications in the coating industry. Gloss depends on optical and rheological properties of complex mixtures, and estimating gloss from basic properties is still a challenge. In order to predict the gloss of an industrial thickened-to-application formulation this work presents a gloss-rheology semi empirical-modeling approach based on a gloss excess function and previous work from other authors. A new matt (low gloss) hybrid waterborne polyurethane dispersion composed out of a self-matting agent (A) and a traditional silica-based matting agent (B) has been studied, and the resulting gloss of the mixture has been correlated to pure component gloss values and dynamic viscosity at medium shear rate. Several modeling options have been tested and their goodness of fit has been determined. The most promising options have been selected and validated towards untrained data sets.

Effects of trimethylol propane and AAS salt on properties of waterborne polyurethane with low gloss

Abstract A series of waterborne polyurethane(WPU) dispersions containing different amounts of trimethylol propane(TMP) and/or 2-[(2-aminoethyl)amino]ethanesulfonic acid sodium salt (AAS salt), were synthesized by prepolymer emulsification process. The effects of TMP and AAS salt on properties of WPU dispersions were discussed to find out the appropriate formulation of WPU dispersion with low gloss. The results showed the particle size of WPU increased as the TMP content increased, but a decrease to the gloss and transparency. Spherical granules emerged in the surface morphology of WPU films when the TMP content exceeded beyond 1% by weight via scanning electron microscope (SEM). In contrast, as the AAS salt content increased, the particle size of WPU decreased, and the gloss and transparency increased. It was most worth noting that the dispersion stability of WPU dispersions was enhanced dramatically with the increase of AAS salt content by measuring the Zeta potential of emulsion. Therefore, WPU dispersions with low gloss and high dispersion stability can be prepared successfully with the AAS content of 0.5% by weight and the TMP content of 1%–1.5% by weight when other influence factors were fixed to a suitable condition.

Improvement of the stainless steel electropolishing process by organic additives

Abstract The influence of organic additives on the process of surface electropolishing of AISI 304 type steel was determined. Additives were selected in initial potentiodynamic tests pursuant to the plateau analysis on the current/potential curves. The assessment of the operational effectiveness of additives consisted in determining the relationship between surface gloss after electropolishing and the mass loss of the sample and in determining surface roughness. The applied electropolishing bath consisted of a mixture of concentrated acids: H3PO4 and H2SO4, and the following organic additives were used: triethylamine, ethanolamine, diethanolamine, triethanolamine, diethylene glycol monobutyl ether and glycerol. The best electropolishing result, i.e. low roughness and high gloss of stainless steel surface with a relatively low mass loss of the sample at the same time were obtained for baths containing triethanolamine.

Characterization of immiscibly blended polyurethane coatings part 1: selective staining for enhanced micro-Raman spectroscopy

Raman spectroscopy (RS) mapping of the selective infiltration of styrene monomer has been developed as a protocol for polymeric phase identification in resin-blended thermoset powder coatings. Blends of incompatible acrylic polyols, with low and high hydroxyl contents, combined with matting agents and pigments, were crosslinked to produce unique low gloss thermosets. The low reflectance originated from a synergistic effect between the polymeric phase separation and the incorporation of the matting agents and pigments. RS conclusively identified the phases within the blended film using polyester-embedded cross-section samples. Further analysis has revealed that monomeric styrene from the polyester-embedding resin produced the spectroscopic handle necessary for domain identification. Preferential infiltration of styrene was therefore investigated through dip and vapor staining of the blended and individual resin films. The spectroscopic handle had manifested through the consistent infiltration of styrene within the low hydroxyl film. The contamination in the cross-sections was eliminated when an epoxy-embedding resin was utilized, which produced no such marker peak in the ensuing spectra. These observations led to the development of the described selective staining protocol for micro-Raman analysis, which enabled very reproducible results for enhanced chemical mapping of phase-separated coatings.

Synthesis and characterization of multi‐hollow opaque polymer pigments

ABSTRACTA new generation multihollow opaque polymer pigment was synthesized by suspension polymerization of “water‐in‐oil‐in‐water” emulsion method, where methyl methacrylate and ethylene glycol dimethacrylate monomer mixture was used as oil phase. The effects of surfactant and cosurfactant composition in terms of “hydrophilic/lipophilic balance” on the stability of the “water‐in‐oil” emulsion and the size of water droplets were studied. Low droplet sizes and the optimum stability were obtained with “Span 80&Tween 80” surfactant mixture at an HLB value of 8. The desired size distribution was obtained at “monomer/surfactant/water” ratio of 75.5/9.4/15.1 at an ultrasonic mixing power of 80 W lasting for 30 s. The surface morphology and hollow structure of polymer pigments were analyzed by scanning and transmission electron microscopy techniques. L*a*b color and gloss properties of polymer pigments were examined. The opacity values were assessed by contrast ratio measurements, and the pigments provided up to 97.3% opacity with 50% v/v solid content in resin. In addition, the pigments exhibited low gloss values and yielded matte films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43696.

Preparation and characterization of antiglare waterborne polyurethane

An antiglare coating was prepared by controlling the content of 2-[(2-aminoethyl)amino] ethyl sulfonic acid sodium and hydrazine hydrate in waterborne polyurethane. It possessed low gloss and high light transmission in the presence of nano-spheres.

Next Generation of Low Gloss, Low Temperature Cure Polyester Powder Coating Resins

Next Generation of Low Gloss, Low Temperature Cure Polyester Powder Coating Resins

Scattering and polarization properties of the scarab beetle Cyphochilus insulanus cuticle.

Optical properties of natural photonic structures can inspire material developments in diversified areas, such as the spectral design of surfaces for camouflage. Here, reflectance, scattering, and polarization properties of the cuticle of the scarab beetle Cyphochilus insulanus are studied with spectral directional hemispherical reflectance, bidirectional reflection distribution function (BRDF) measurements, and Mueller-matrix spectroscopic ellipsometry (MMSE). At normal incidence, a reflectance (0.6-0.75) is found in the spectral range of 400-1600 nm and a weaker reflectance <0.2 in the UV range as well as for wavelengths >1600 nm. A whiteness of W=42 is observed for mainly the elytra of the beetle. Chitin is a major constituent of the insect cuticle which is verified by the close similarity of the measured IR spectrum to that of α-chitin. The BRDF signal shows close-to-Lambertian properties of the beetle for visible light at small angles of incidence. From the MMSE measurement it is found that the beetles appear as dielectric reflectors reflecting linearly polarized light at oblique incidence with low gloss and a low degree of polarization. The measured beetle properties are properties that can be beneficial in a camouflage material.