This thesis considers the fruit of the tara tree (Caesalpinia spinosa) as a sustainable source for tanning agents and proposes alternatives to the commercial mineral salts and vegetable extracts to comply with an increasing demand that concerns lower carbon footprint and health safety. Taxonomy of the tree is described and the substances contained in the fruit are chemically characterized in order to justify that tara farm forestry is economically viable and to secure a potential worth. The value chain is fully described from fruit collection in remote Andean regions to the export for the most important leather markets. Although tara tannins have been used in the leather industry and its properties being well known, the experimental part of the work aims to optimize innovative formulations using tara as wet-white pre-tanning agent. Combinations with a selected syntan used for wet white and final article recipes are proposed / Esta tesis considera el fruto del árbol de tara (Caesalpinia spinosa) como fuente sostenible de taninos para la curtición del cuero y propone alternativas para las sales minerales y los extractos vegetales como respuesta a la creciente demanda para reducir el impacto medioambiental y la seguridad de los artículos de consumo. Se describe la taxonomía del árbol así como la caracterización de su fruto para justificar la silvicultura como práctica económicamente viable y asegurar su valor y la cadena desde la recolección de los frutos en las regiones andinas hasta la exportación a los mercados más importantes de la industria del cuero. Aunque los taninos de la tara ya se usan para la fabricación de cueros desde épocas remotas y sus propiedades están reconocidas, la sección experimental de este trabajo se orienta a optimizar fórmulas innovadoras utilizando la tara como agente de curtido wet-white. Se proponen fórmulas para artículos finales.

Content: Leather and leather products are known for its durability and luxuries which makes it more unique among the other synthetic materials. Breathability and visco-elastic properties make leather unique choice of biomaterial. Utilization of leathers in marine based applications is limited owing to reactivity of leather towards salt and weather conditions. Moreover, the choice of raw materials and chemicals used during leather manufacture has greatly influence the properties of the leather. An attempt has been made to understand the influence of sea conditions on leathers. Conventional chrome tanned and vegetable tanned leathers were incubated in sea water and subsequently processed into post tanning to evaluate the physical properties. To understand, the leaching of chemicals, dyed leathers are incubated at different humidity and saline conditions. Interestingly, chrome tanned leathers found to be friendlier to marine conditions whereas, vegetable tanned leathers lead to leaching of chemicals. Furthermore, leaching of chromium is negligible, and crust leathers resulted in soft leathers. Prolonged exposure of chrome tanned leathers under salt stress leads to more softness. This might be due to saline stress to the skin matrix. Moreover, the computability of conventional leather chemicals were also tested using sea water. The research provides a new insight on fine tuning the chemicals to suit marine based applications. Take-Away: A new insight on fine tuning the chemicals to suit marine based applications.

Content: The use of vegetable tanning agents alone for pre-tanning as an alternative to synthetic or chromiumcontaining tanning agents is one way of improving sustainability and ecology in leather production. In recent years, a new group of secondary plant compounds, the iridoids or secoiridoids, has been discovered for use as tanning agents. Due to their molecular structure, these substances probably have a reaction mechanism similar to glutaraldehyde, which means that known disadvantages of conventional vegetable tanning such as long process times or weak interactions can be avoided. Currently, a tanning agent from olive leaves with cross-linking active substances deriving from the secoiridoid Oleuropein is commercially available. In order to extend the product range of alternative vegetable tanning agents with covalent cross-linking mechanism by native raw material, we screened a number of further plants for such crosslinking active substances in a preceding project. Extracts from privet leaves showed a particularly high crosslinking activity. Privet belongs to the Oleacea family and is common in Asia with several species. In Europe, the species Ligustrum vulgare can be found everywhere, especially as a hedge plant. In addition to Oleuropein, the privet extracts contain a high proportion of the secoiridoid Ligustraloside A. The secoiridoids are deglycosylated during extraction and thus converted into an activated state. The analytical determination of the active secoiridoid degradation products is not yet possible, so that the quantitative determination of the tannin content is made more difficult. Here, we aimed to develop a technology for the production of leather that is exclusively pre- tanned with privet tanning agents. The development includes the production, characterization and optimization of the plant extracts, the development of the pre-tanning technology and the adaptation of the wet end for the corresponding application areas. The leathers which have been manufactured show high shrinkage temperature and good mechanical properties. They show an inherent coloring, but seem to be suitable for use in automotive interiors, as a comparison of the test results with the technical delivery conditions of automobile manufacturers shows. Take-Away: With a new tanning agent from a native widespread plant, leather of good quality can be produced.

Content: In order to develop a sustainable and low-cost route for tanning, the stabilization of the collagen fibers of the hides with silica compounds has been investigated for many years. In this context, silica nanoparticles have been studied for application in tanning due to their small size and ability to combine with polymeric substrates. This work investigates the potentialities and limitations of the use of alkoxysilanes in leather tanning, introducing silica nanoparticles in the hides, aim for process and product innovation in leather industry. The synthesis of silica nanoparticles was carried out by a typical sol-gel Stöber process. From the silica precursor tetraethoxysilane (TEOS), ammonium hydroxide as catalyst, ethanol and water, the formation of nanoparticles dispersion takes place. Vegetable tanning process was explored by introducing the silica nanoparticles in this stage starting from pickled cattle hide. Shrinkage temperature, tensile strength, softness and color fastness to light were evaluated in the leather samples. The results achieved show that the tanning experiment with only silica, without other tanning agent, did not reach the minimum shrinkage temperature required to be labeled as tanned leather. Conversely, in the presence of vegetable tannin, the shrinkage temperature reached 80°C. The physical-mechanical properties indicated that the enhanced on the tensile strength of vegetable leathers with nanosilica was about 50% and their softness was not affected by the introduction of silica. A lighter colored leather was generated with silica but less stable to light. The tanning chemistry involving silica nanoparticles and collagen is complex, therefore, more studies are needed to explore the influence of silanes on hide stabilization. Take-Away: The physical-mechanical properties indicated an increase on the tensile strength of vegetable leather. Silica did not affected the softness of the leather. A lighter colored leather was generated with the addition of the silica nanoparticles in vegetable tanning.

Läder som material har använts av människor i århundraden och är ett av de mest tåliga materialen som finns idag. Detta leder till att det produceras extremt höga mängder läder där den högsta andelen som produceras är kromgarvat läder, som står för cirka 90 procent av den totala läderproduktionen. I och med dagens medvetenhet kring miljö och hur läder påverkar denna efterfrågas alternativa material. Piñatex är ett material där man använt sig av bladen på ananasplantan för att sedan producera ett nonwoven-material som är likt läder, trots att det inte skapats som ett substitut till läder, men användningsområdena är desamma. Piñatex kan vara ett alternativt material när det gäller hållbarhet över tid men även ur miljösynpunkt. I denna rapport är syftet att studera tillverkningsprocesserna för Piñatex, kromgarvat läder och vegetabiliskt garvat läder för att ge ökad förståelse för deras miljöpåverkan. Dessutom utförs materialtester för att se hur de tekniska egenskaperna skiljer sig mellan materialen. Testresultaten i denna studie visar på att materialen har olika för- och nackdelar beroende på vilket test som utförts. Vidare är det svårt att veta exakt hur stor miljöpåverkan de olika tillverkningsprocesserna har, men kromgarvning är den process som med största sannolikhet leder till störst inverkan på miljön. I slutändan handlar ett materials önskvärdhet om preferenser från användarna och i vilket syfte ett material ska användas. / Leather has been used by humans for centuries and it is one of the most resistant materials that exists today. This leads to a high production of leather, where the largest part comes from chrome tanning, which stands for approximately 90 % of the total leather industry. Because of today’s awareness surrounding the environment and how leather affects it, demand for alternative materials are increasing. Piñatex is a material based on the leaves of the pineapple plant, which is turned into a non woven material, looking alot like leather. Although it is not created as a substitute for leather, the areas of use are the same. Piñatex can be an alternative material when it comes to durability but also from an environmental point of view. The purpose of this report is to study the manufacturing processes for Piñatex, chrome tanned leather and vegetable tanned leather to yield a higher understanding for their environmental impact. Futhermore, material testing is carried out to see how the technical properties differentiate between the materials. Test results from this study show that the materials have different advantages and disadvantages depending on which test has been carried out. It is hard to know exactly how big the environmental impact from the different manufacturing processes are, but chrome tanning is probably the one with the highest impact. In the end, the desirability of a certain material all comes down to user preferences and for which purpose the material will be used.

Content: Traditional chromium tanning agents cannot conform to the requirement of sustainable and cleaner development under current leather producing. Compared with chromium tanning agents, vegetable tanning agents have been widely used in tanning process by the virtue of its non-toxicity, low pollution, biodegradability and regenerability. In this study, a novel vegetable tanning agent was extracted from the Coriaria nepalensis bark (CNB) by alkali solution. In order to optimize extraction conditions, the response surface Box-Behnken design was used in this experiment. The key factors including alkali concentration, extraction time, extraction temperature, liquid to solid ratio and extraction times. The experimental results showed that under the conditions of 0.22% sodium hydroxide concentration, 63 min extraction time, 83℃ extraction temperature and 24 liquid to solid ratio, the yield of tannins in CNB is 15%, tannins in extractives up to 50%. Afterwards, the composition and molecular mass were evaluated, we discovered that the extractives belong to hydrolyzable tannins and its molecular mass ranged from 599 to 1457 Da. Furthermore, the extractives were used in sheep garment tanning process. The results showed that the shrinking temperature of tanned leather can reach to 75 ℃. Applying the extractives to the retanning process, the shrinking temperature of retanned leather can reach to 130 ℃. Surprisingly, the color of tanned or retanned leather coincide with the requirement of light leather. Take-Away: 1 New vegetable tanning agent from Coriaria nepalensis bark. 2 The vegetable tanning agent belongs to hydrolyzable tannins and its molecular mass ranged from 599 to 1457 Da. 3 The shrinking temperature of tanned leather and retanned leather can reach to 75 ℃ and 130 ℃ respectively.

Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-18T14:43:37Z No. of bitstreams: 1 CARLOS ROBERTO DE LIMA - TESE (PPGRN) 2011.pdf: 6096425 bytes, checksum: e79260d5348e29924543c57235a532a5 (MD5) / Made available in DSpace on 2018-09-18T14:43:37Z (GMT). No. of bitstreams: 1 CARLOS ROBERTO DE LIMA - TESE (PPGRN) 2011.pdf: 6096425 bytes, checksum: e79260d5348e29924543c57235a532a5 (MD5) Previous issue date: 2011-02-25 / CNPq / Nas últimas décadas, com o crescimento populacional e os avanços tecnológicos ocorridos, houve aumento significativo da pressão sobre a flora nativa de muitas regiões, em diferentes partes do mundo, inclusive na região semi-árida do Brasil (Caatinga), nas mais variadas formas, destacando-se a produção de lenha e de carvão vegetal e, utilização das cascas do angico-vermelho (Anadenanthera colubrina (Vell.) Brenan var. cebil (Gris.) Alts.) como curtente vegetal para a produção de couros. A exploração florestal tem ocorrido sem atender a quaisquer dos preceitos para o regime de manejo sustentável, fazendo com que a preocupação com o uso indiscriminado das florestas aumente que, como consequência, resultará no surgimento de áreas degradadas. Apesar da importância da vegetação da Caatinga como fonte de energia e para a produção de taninos (cascas) é grande a carência de informações, principalmente, tecnológicas sobre os temas. Reconhecendo a importância do ecossistema Caatinga para a Região Nordeste do Brasil, a necessidade de maior conhecimento sobre a sua flora, bem como a escassez de pesquisas nesta área, o desenvolvimento desta tese teve como objetivos contribuir com a disponibilização de informações sobre o potencial para a produção de extratos tânicos (taninos vegetais) a partir de espécies florestais da Caatinga e avaliar a viabilidade técnica da utilização dos extratos obtidos para utilização no processo de curtimento de peles caprinas, para a produção de couros. Pretendeu-se assim, contribuir para redução da pressão antrópica sobre a espécie florestal angicovermelho (Anadenanthera colubrina var. cebil), que ocorre de forma mais acentuada na mesorregião do Cariri paraibano, por meio do desenvolvimento de pesquisas tecnológicas de utilização dos extratos tânicos (taninos vegetais) das espécies juremapreta (Mimosa tenuiflora) e jurema-vermelha (Mimosa arenosa) no processo de curtimento de peles caprinas. Pretendeu-se ainda, analisar a viabilidade técnica da utilização dos extratos tânicos das espécies, por meio das características físicomecânicas dos couros produzidos. Os extratos tânicos das espécies jurema-preta e jurema-vermelha produziram couros com bom aspecto e de coloração clara, com boa maciez e flexibilidade, e apresentaram características físico-mecânicas superiores as produzidas com o extrato de angico-vermelho. O extrato tânico da espécie jurema-preta foi superior aos extratos das demais espécies. O extrato de jurema-vermelha foi superior ao de angico-vermelho, tendo se igualado no quesito alongamento e apenas na direção paralela. Com relação às características relativas à flor, novamente o extrato tânico da espécie jurema-preta demonstrou-se superior aos demais, tanto na distensão como para a resistência à ruptura da flor. O extrato de jurema-vermelha foi superior ao de angicovermelho apenas para a distensão da flor, enquanto que para a resistência à ruptura da flor eles se equivalem, com pequena superioridade numérica para o de juremavermelha. Os resultados da pesquisa permitem concluir que é tecnicamente possível promover uma significativa redução da pressão antrópica sobre a espécie florestal angico-vermelho (Anadenanthera colubrina var. cebil), por meio da substituição do uso de cascas de angico-vermelho por extratos tânicos obtidos das espécies jurema-preta (Mimosa tenuiflora) e jurema-vermelha (Mimosa arenosa) no processo de curtimento de peles caprinas para a produção de couros. / In recent decades with population growth and technological advances that have occurred a significant increase pressure on the native flora in many regions in different parts of the world including semi-arid region of Brazil (Caatinga) in varied ways, there is the production of firewood and charcoal, and use the bark of angico-vermelho (Anadenanthera colubrina (Vell.) Brenan var. cebil (Gris.) Alts.) as vegetable tanning agent for leather production. The logging has occurred without regard to any of the provisions for the sustainable management regime causing concern about the indiscriminate use of forests that increase as a consequence result in the appearance of degraded areas. Despite the importance of the Caatinga vegetation as a source of energy and the production of tannins (bark) is a great lack of information mainly on technological issues. Recognizing the importance of the Caatinga ecosystem in the northeastern region of Brazil the need for more knowledge about its flora as well as the scarcity of research in this area developing this thesis aimed to contribute to the provision of information about the potential for production of tannin extracts (tannins) from the Caatinga forest species and evaluate the technical feasibility of the use of extracts for use in the process of tanning hides of goats for the production of leather. It was intended thus contribute to reducing human pressure on forest species angicovermelho (Anadenanthera colubrina var. cebil) which occurs more steeply in the Cariri region through the development of technological research for the use of tannin extracts (tannins) from the species jurema-preta (Mimosa tenuiflora) and jurema-vermelha (Mimosa arenosa) in the process of tanning goat production. The intention was also to examine the technical feasibility of the use of tannin extracts of species by means of physical and mechanical properties of leather produced. The tannin extracts of the jurema-preta and jurema-vermelha species produced leather look good and light coloring with good softness and flexibility and showed physical and mechanical properties superior to those produced with the extract of the angico-vermelho. The tannic extract of the Jurema’s species was superior to the extracts of other species. The tannic extract of the jurema-vermelha was superior to that of angico-vermelho and equaled only in the elongation in the parallel direction. With respect to characteristics related to flower again the tannic extract the jurema’s species shown to be superior to others much as in strain to the tensile strength of the flower. The extract the juremavermelha was superior to the angico-vermelho only to distend the flower while for the tensile strength of the flower they are equal with a slight numerical superiority for a jurema-vermelha. The survey results support the conclusion that it is technically possible to promote a significant reduction of anthropogenic pressure on forest species angico-vermelho (Anadenanthera colubrina var. cebil), by substituting the use of angico-vermelho bark for the tannin extracts obtained by species jurema-preta (Mimosa tenuiflora) and jurema-vermelha (Mimosa arenosa) in the process of tanning goat skins for leather production.

The importance of skin processing technologies, in the history and dispersal of humankind around the planet cannot be overstated. This area of material culture is often underrepresented as a research topic, and has been hampered, in part, by the lack of a systematic analysis methodology targeted at specifically this material type. This research aimed to develop a methodology for determining the tanning technologies in use during prehistory, from extant archaeologically recovered processed skin objects. The methodology is a product of macroscopic and microscopic observations of a large sample reference collection, used to produce a database of defining characteristics and tendencies for each of six tannage types. The sample collection is made up of twenty-two species identified as economically important from both Europe and North America. Six sample pieces of skin were taken from a single individual of each of the twenty-two species, and processed using six tanning technologies, the use of which covered a large geographic area and time frame. A second reference collection of clothing and utilitarian items, made from traditionally processed skins, was used to add a section of in-life use traces to the database of discriminating traits. The developed methodology was tested by examining archaeologically recovered and ethnographically collected skin objects, from museum collections across North America and Europe. Objects from many different preservation contexts, including wet, dry, and frozen sites were analysed to determine whether or not the discriminating traits survived interment. It was found that defining characteristics and tendencies do exist between the main tannage technologies, and can be recorded at multiple levels of observation. The analysis of skin objects in museum collections confirmed that at least some defining characteristics and tendencies survived in all preservation contexts. In addition, the preservation of in-life use traces proved to be diagnostic of not only tannage type, but small sections of chaîne opératoire and object biography as well. Overall, this research has demonstrated that archaeologically preserved objects made from processed skin can provide information about the tannage technologies in use prehistorically, as well as more detailed information such as manufacturing sequences and the conditions of use an object was subjected to. Thus, analysis of this nature can be used to access information on a more individual level than previously believed.