Over the last several years, nanoparticles have come under scrutiny for adverse health effects. Nanoparticles are ultrafine particles between 1 to 100 nanometers in diameter. (To put this in perspective, the average human hair is around 80,000 nanometers thick.) Because of their size, which can be engineered and manipulated at the atomic or molecular level, nanoparticles exhibit unique physical, chemical, and biological properties. Titanium dioxide is one of the most commonly produced nanoparticles in the world.
Pure PVB is non-toxic and harmless to human body. In addition, ethyl acetate or alcohol can be used as solvent, so PVB is widely used in printing ink of food containers and plastic packaging in European and American countries.
Storage safety properties
PVB can be stored for two years without affecting its quality as long as it is not in direct contact with water; PVB shall be stored in a dry and cool place and avoid direct sunlight. Heavy pressure shall be avoided during PVB storage.
Solubility
PVB is soluble in alcohol, ketone, ester and other solvents. The solubility of various solvents changes according to the functional group composition of PVB itself. Generally speaking, alcohol solvents are soluble, but methanol is more insoluble for those with high acetal groups; The higher the acetal group, the easier it is to dissolve in ketone solvents and ester solvents;
PVB is easily soluble in cellosolve solvents; PVB is only partially dissolved in aromatic solvents such as xylene and toluene; PVB is insoluble in hydrocarbon solvents.
Viscosity characteristics of PVB solution
The viscosity of PVB solution is greatly affected by the formula of solvent and the type of solvent; Generally speaking, if alcohol is used as solvent, the higher the molecular weight of alcohol, the higher the viscosity of PVB solution;
Aromatic solvents such as xylene and toluene and hydrocarbon solvents can be used as diluents to reduce the viscosity of PVB solution; The effect of PVB chemical composition on viscosity is summarized as follows: under the same solvent and the same content of each base, the higher the degree of polymerization, the higher the solution viscosity; Under the same solvent and the same degree of polymerization, the higher the acetal group or acetate group, the lower the solution viscosity.
Dissolution method of PVB
Where mixed solvents are used, the dissolution step is to first put aromatic solvents (such as xylene, toluene, etc.) or ester solvents (such as n-butyl acetate, ethyl acetate, etc.) into the mixing, slowly put PVB into the mixing, and then add alcohol solvents (such as n-butanol, ethanol, etc.) after PVB is dispersed and expanded,
At this time, the dissolution time can be shortened by heating; Using this dissolution method, the formation of lumpy PVB can be avoided (because the dissolution time will be several times after the formation of lumpy PVB), so the dissolution speed can be accelerated. Generally, the ratio of aromatic and alcohol solvents is 60 / 40 ~ 40 / 60 (weight ratio), and PVB solution with low viscosity can be prepared.
The solvent composition contains 2 ~ 3wt% water, which can improve the hydrogen bonding strength of alcohol solvents and help the solubility of PVB.
Processing properties
Although PVB resin is a thermoplastic, it has little processability before plasticizer is added. Once plasticizer is added, its processability is very easy.
The purpose of general coatings and adhesives is to change the resin characteristics by adding plasticizers to meet the application requirements, such as film softness, reducing the TG point of the resin, reducing the heat sealing temperature, maintaining low-temperature softness, etc.
Compatibility
PVB can be compatible with a variety of resins, such as phenolic resin, epoxy resin, alkyd resin and MELAMINE resin.
B-08sy, b-06sy and b-05sy with high acetal degree can be mixed with nitrocellulose in any proportion. PVB and alkyd resin are partially compatible. General PVB is compatible with low molecular weight epoxy resin, while high molecular weight epoxy resin needs PVB with high acetal degree to be compatible with each other.
Cet article traite de la découverte de lithopone phosphorescent sur des dessins à l'aquarelle, datés entre 1890 et 1905, de l'artiste Américain John La Farge et de l'histoire du lithopone dans l'industrie des pigments à la fin du 19e et au début du 20e siècle. Malgré de nombreuses qualités souhaitables pour une utilisation en tant que blanc dans les aquarelles et les peintures à l'huile, le développement du lithopone comme pigment pour artistes a été compliqué de par sa tendance à noircir lorsqu'il est exposé au soleil. Sa disponibilité et son usage par les artistes demeurent incertains parce que les catalogues des marchands de couleurs n'étaient généralement pas explicites à indiquer si les pigments blancs contenaient du lithopone. De plus, lors d'un examen visuel, le lithopone peut être confondu avec le blanc de plomb et sa phosphorescence de courte durée peut facilement être ignorée par l'observateur non averti. À ce jour, le lithopone phosphorescent a seulement été documenté sur une autre œuvre: une aquarelle de Van Gogh. En plus de l'histoire de la fabrication du lithopone, cet article décrit le mécanisme de sa phosphorescence et son identification à l'aide de la spectroscopie Raman et de la spectrofluorimétrie. En este artículo se discute el descubrimiento del litopón fosforescente en dibujos a la acuarela por el artista americano John La Farge, fechados de 1890 a 1905, y la historia del litopón en la industria de los pigmentos a finales del Siglo XIX y principios del Siglo XX. A pesar de tener muchas cualidades deseables para su uso en pintura para acuarela o pinturas al óleo blancas, el desarrollo del litopón como pigmento para artistas fue obstaculizado por su tendencia a oscurecerse con la luz solar. Su disponibilidad para los artistas y su adopción por ellos sigue siendo poco clara, ya que por lo general los catálogos comerciales de los coloristas no eran explícitos al describir si los pigmentos blancos contenían litopón. Además, el litopón se puede confundir con blanco de plomo durante el examen visual, y su fosforescencia de corta duración puede ser fácilmente pasada por alto por el observador desinformado. A la fecha, el litopón fosforescente ha sido documentado solamente en otra obra mas: una acuarela por Van Gogh. Además de la historia de la fabricación del litopón, el artículo detalla el mecanismo para su fosforescencia, y su identificación con la ayuda de espectroscopía de Raman, y de espectrofluorimetría. Este artigo discute a descoberta de litopônio fosforescente em desenhos de aquarela do artista americano John La Farge datados de entre 1890 e 1905 e a história do litopônio na indústria de pigmento no final do século XIX e início do século XX. Apesar de ter muitas qualidades desejáveis para o uso em aquarela branca ou tintas a óleo, o desenvolvimento do litopônio como um pigmento de artistas foi prejudicado por sua tendência a se escurecer na luz solar. Sua disponibilidade para e uso por parte de artistas ainda não está clara, uma vez que os catálogos comerciais dos vendedores de tintas geralmente não eram explícitos na descrição de pigmentos brancos como algo que contém litopônio. Além disso, o litopônio pode ser confundido com o branco de chumbo durante o exame visual e sua fosforescência de curta duração pode ser facilmente perdida pelo observador desinformado. O litopônio fosforescente foi documentado em apenas um outro trabalho até hoje: uma aquarela de Van Gogh. Além da história da manufatura do litopônio, o artigo detalha o mecanismo para a sua fosforescência e sua identificação auxiliada pela espectroscopia de Raman e espectrofluorimetria.