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Abstract(s)
O objetivo principal do trabalho foi o desenvolvimento de um método de controlo de qualidade da cor para uma tinta aplicada em vidro e como objetivo secundário o controlo da qualidade diária de produtos desenvolvidos pela empresa que são aplicados à indústria do mobiliário. Inicialmente realizou-se um estudo dos parâmetros de controlo da qualidade dos produtos fabricados. Verificou-se que o registo de inconformidades era muito baixo e que o sistema de controlo era simples e eficaz contabilizando apenas um ou dois parâmetros de análise a cada produto. Como a margem de tempo de estudo era pequena optou-se apenas por se desenvolver um procedimento para controlar a cor de uma tinta, em base aquosa ou solvente. A técnica de análise base utilizada foi a espetrofotometria de refletância que permitiu estabelecer espectros em função do comprimento de onda (350-750 nm). Estes valores foram convertidos nos parâmetros de cor L, a, b, que correspondem à luminosidade, à coordenada do verde/vermelho e à coordenada do amarelo/azul, respetivamente, e incluídos numa base de dados, que permitiu a comparação com os mesmos das 70 tintas produzidas. Quando a diferença entre os valores padrão e objetivo foi superior a 1 identificou-se o fator de diluição do pigmento principal ou a necessidade de inclusão de outros pigmentos (azul, amarelo, verde, vermelho, preto e branco). Aplicou-se matrizes de correlação aos valores de L, a, b, das tintas fabricadas com o objetivo de perceber qual dos parâmetros influenciava mais negativamente o valor da diferença da cor, E. E concluiu-se que quando se considerou todas as tintas ou apenas as que continham pigmento de cor verde ou amarelo, quanto mais preto/branco continha a tinta requisitada, maior era a diferença de cor obtida. Esta diferença também foi maior e diretamente proporcional à quantidade respetiva de pigmentos vermelhos ou azuis.
The main objective of the work was the development of a method for controlling color in a glass ink and, as a secondary objective, the daily quality control of products developed by the company that are applied to the furniture industry. Initially a study of the quality control parameters for the manufactured products was carried out. It was found that the record of nonconformities was very low and that the control system was simple and effective accounting for only one or two parameters analysis for each product. As the study timeframe was small it was only chosen to develop a procedure to control the color of an ink on an aqueous or solvent basis. Reflectance spectrophotometry was the analysis technique used that allowed to establish spectra as a function of wavelength (350-750 nm). These values were converted to the color parameters L, a, b, which correspond to the brightness, the green/red coordinate and the yellow/blue coordinate, respectively, and included in a database, which allowed the comparison with the same of the 70 paints produced. When the difference between the standard and objective values was greater than 1, the main pigment dilution factor or the need to include other pigments (blue, yellow, green, red, black and white) was identified. Correlation matrices were applied to the values of L, a, b, for the manufactured paints in order to perceive which of the parameters influenced more the value of the color difference, E. It was concluded that when all inks or only those containing green or yellow pigment were considered, the blacker/whiter the ink required, the greater the difference in color obtained. This difference was also greater and directly proportional to the respective amount of red or blue pigments.
The main objective of the work was the development of a method for controlling color in a glass ink and, as a secondary objective, the daily quality control of products developed by the company that are applied to the furniture industry. Initially a study of the quality control parameters for the manufactured products was carried out. It was found that the record of nonconformities was very low and that the control system was simple and effective accounting for only one or two parameters analysis for each product. As the study timeframe was small it was only chosen to develop a procedure to control the color of an ink on an aqueous or solvent basis. Reflectance spectrophotometry was the analysis technique used that allowed to establish spectra as a function of wavelength (350-750 nm). These values were converted to the color parameters L, a, b, which correspond to the brightness, the green/red coordinate and the yellow/blue coordinate, respectively, and included in a database, which allowed the comparison with the same of the 70 paints produced. When the difference between the standard and objective values was greater than 1, the main pigment dilution factor or the need to include other pigments (blue, yellow, green, red, black and white) was identified. Correlation matrices were applied to the values of L, a, b, for the manufactured paints in order to perceive which of the parameters influenced more the value of the color difference, E. It was concluded that when all inks or only those containing green or yellow pigment were considered, the blacker/whiter the ink required, the greater the difference in color obtained. This difference was also greater and directly proportional to the respective amount of red or blue pigments.
Description
Keywords
Paints Varnish Quality control