WO2019185824A1 - Treatment of leather including employing pectin - Google Patents
Treatment of leather including employing pectin Download PDFInfo
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- WO2019185824A1 WO2019185824A1 PCT/EP2019/057907 EP2019057907W WO2019185824A1 WO 2019185824 A1 WO2019185824 A1 WO 2019185824A1 EP 2019057907 W EP2019057907 W EP 2019057907W WO 2019185824 A1 WO2019185824 A1 WO 2019185824A1
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- pectin
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Classifications
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C3/00—Tanning; Compositions for tanning
- C14C3/02—Chemical tanning
- C14C3/08—Chemical tanning by organic agents
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C3/00—Tanning; Compositions for tanning
- C14C3/02—Chemical tanning
- C14C3/28—Multi-step processes
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C9/00—Impregnating leather for preserving, waterproofing, making resistant to heat or similar purposes
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C9/00—Impregnating leather for preserving, waterproofing, making resistant to heat or similar purposes
- C14C9/02—Impregnating leather for preserving, waterproofing, making resistant to heat or similar purposes using fatty or oily materials, e.g. fat liquoring
Definitions
- the present invention is in the field of leather manufacturing.
- leather manufacturing comprises a process with many possibilities to tailor the product. Variations in raw hides, processing and choice of chemicals enable the leather manufacturer to produce a great variety in end products.
- the process of leather production is versatile, the essence of leather making lies in preserving skins or pelts from putrefaction and further adjustments to meet the demands of the end-users.
- pre-treated hides are tanned, predominantly with metal ions such as chromium (III) ions but several alternatives (including vegetable tanning and synthetic reactive tanning using aldehydes) are also applied.
- the tanning agents interact with the skin collagen, wherein different classes of tanning agent provide different mechanisms of interaction.
- the tanned leather is often not yet suitable for its end application; the uniformity, organoleptic, mechanical and/or other physical properties still need to be adjusted and optimized.
- treatment stages after tanning are employed to modify and further differentiate the leather and make the leather suitable for its end-use. These treatment stages include the employment of chemicals that may result in polluted waste-water streams and undesirable emissions during leather’s lifecycle.
- pectin in the leather manufacturing process and in the leather intermediate and end product. It was surprisingly found that through employing pectin in the leather manufacturing process, leather end products can be obtained having surprisingly good organoleptic properties and/or mechanical and/or other physical properties. Especially the grain appearance, evenness of dyeing, dyeing intensity, grain tightness, softness, fullness, milling pattern and evenness of milling grain can be optimized towards specific needs. Moreover tear strength can be improved. Also excellent levels of light fastness, heat yellowing and fogging can be obtained. Pectin is also found suitable for the manufacturing of waterproof articles.
- pectin can replace synthetic petro-based compounds such as vinyl polymers during leather manufacturing and in the leather intermediate and end product.
- chemicals with a high environmental impact and which need toxic chemicals for producing are replaced with a natural and biodegradable material.
- leather products comprising less poorly degradable chemicals can be produced; as can be deduced from biochemical oxygen demand (BOD) measurements.
- BOD biochemical oxygen demand
- the leather product benefits related to the synthetic petro-based compounds, which are in the area of organoleptic and/or mechanical and/or other physical leather properties, can be realized by replacing these compounds with pectin.
- Pectin is also found suitable for the manufacturing of waterproof articles.
- the invention provides the possibility to efficientlyze currently low-value pectin-rich waste streams, as for example the pectin-rich beet pulp waste stream of sugar production from sugar beets or the pectin-rich coffee pulp waste stream.
- the invention also may provide a more cost efficient alternative for vinyl polymer compounds in leather manufacturing.
- pectin is employed as an aqueous solution during post-tanning.
- the invention concerns a method for treatment of leather, comprising providing leather and contacting the leather with an aqueous phase comprising pectin, wherein the leather is tanned leather.
- the invention also concerns leather comprising pectin, preferably leather impregnated with pectin.
- the invention concern a treated leather obtained by the method for treatment of leather.
- the invention concerns a product, such as a shoe, car upholstery, furniture upholstery, bag, garment and/or accessories comprising the treated leather or the leather comprising pectin.
- Pectins are complex polysaccharides which are found in every plant, in which their function is to give strength to the cell walls, and to adhere the cells together.
- Pectins belong to the class of acid oligosaccharides, which are polysaccharides comprising at least one acidic group selected from the group consisting of N-acetylneuraminic acid, N- glycoloylneuraminic acid, free or esterified carboxylic acid, sulfuric acid group and phosphoric acid group.
- HG homogalacturonan
- GalA D-galacturonic acid residues.
- Branches of neutral mono-, oligo- and/or polysaccharides are present on the HG backbone.
- the linear backbone may be intermittent with rhamnogalacturonan type I (RG-I), a copolymer of rhamnose and o(1 ,4)-linked D-galacturonic acid, resulting in a alternating block copolymer structure comprising RG-I and HG.
- RG-I may comprise branches of neutral mono-, oligo- and/or polysaccharides.
- pectin is characterized as all oligosaccharides and polysaccharides with more than 40 % w/w GalA based on saccharide monomer units.
- the invention concerns the use of oligosaccharides and polysaccharides with more than 40 % w/w GalA based on saccharide monomer units.
- Pectin can be extracted from various types of plants.
- pectin refers to extracted pectin.
- Extracted pectin is to be distinguished from modified pectin, which is chemically, physically or enzymatically modified to alter its properties after extraction.
- Extracted pectin is also to be distinguished from native pectin, which is pectin before extraction. Typical modifications are methoxylation or de-methoxylation, amidation or (partial) depolymerization.
- the native pectin may be altered, for example because the extraction is performed under acidic or caustic conditions. In the context of the current invention, these alterations during extraction do not result in modified pectin; upon extraction extracted pectin is obtained.
- extraction commonly comprises one or more solid/liquid separation steps, filtration steps and/or water removal steps and/or combinations thereof. These steps (further) separate the pectin from the plant materials and concentrate the pectin.
- Pectin is commercially mainly extracted from citrus fruit, apples or sugar beet, which yields citrus pectin, apple pectin or sugar beet pectin.
- pectin is also known to be extracted from sunflower head residues, mango peel, yellow passion fruit rind, coffee pulp and cashew apple pomace, which yields sunflower pectin, mango pectin, yellow passion fruit pectin, coffee pectin and cashew apple pectin.
- the pectin is selected from the group of citrus pectin, sugar beet pectin, apple pectin, sunflower pectin, mango pectin, yellow passion fruit pectin, coffee pectin and cashew apple pectin; more preferably the pectin is selected from the group of citrus pectin, sugar beet pectin and apple pectin even more preferably from the group of citrus pectin and sugar beet pectin, most preferably the pectin is sugar beet pectin. Also mixtures of pectin from different origin may be used. Origin of pectin in the context of this document refers to the plant the pectin is extracted from.
- a combination of two or more different pectins is applied selected from the group of citrus pectin, sugar beet pectin, apple pectin, sunflower pectin, mango pectin, yellow passion fruit pectin, and cashew apple pectin.
- the pectin is not fruit pectin, more preferably the pectin is not apple pectin, most preferably the pectin is not derived from cider apples.
- Pectin can be divided into two main categories: high methoxylated pectin (HM), which is characterized by a degree of methoxylation above 50% and low methoxylated pectin (LM) having a degree of methoxylation below 50%.
- HM high methoxylated pectin
- LM low methoxylated pectin
- degree of methoxylation also referred to as DE or“degree of esterification” is intended to mean the extent to which free carboxylic acid groups contained in the homogalacturonan chain have been esterified (e.g. by methoxylation or ethoxylation).
- the pectin is preferably high methoxylated pectin (HM). However, under different circumstances and in another embodiment according to the present invention the pectin is preferably low methoxylated pectin (LM).
- the pectin is preferably characterized by a degree of methoxylation above 20%, preferably above 35%, more preferably above 50%, even more preferable above 60% most preferably above 75%.
- the pectin is preferably characterized by a degree of methoxylation below 75%, preferably below 65%, more preferably below 50%, even more preferable below 35% most preferably below 25%.
- the pectin is preferably characterized by a degree of methoxylation from 10% to 90%, preferably from 25% to 75%, more preferably from 35% to 65%, even more preferable from 50% to 65%.
- Methoxylation affects the charge on the pectin and may therefore influence leather penetration and interaction with the collagen.
- High methoxylated pectin therefore may diffuse more rapidly in the leather matrix resulting in higher uptake, shorter processing times and optimal organoleptic and mechanical properties.
- high methoxylated pectin may be better suitable as a filler and for use during fatliquoring.
- Low methoxylated pectin on the other hand, may interact to a higher extent with the collagen and therefore induce improved mechanical and organoleptic properties.
- the pectin may also be amidated giving pectin with a certain“degree of amidation” or amidated pectin.
- amidation galacturonic acid is converted with ammonia to carboxylic acid amide.
- degree of amidation also referred to as DA is intended to mean the extent to which free carboxylic acid groups contained in the homogalacturonan chain have been amidated.
- the pectin is preferably amidated. However, under different circumstances and in another embodiment according to the present invention the pectin is preferably not amidated. In one embodiment the pectin is preferably characterized by a degree of amidation above 10%, preferably above 20%, more preferably above 30%. In one embodiment the pectin is preferably characterized by a degree of amidation below 40%, preferably below 30%, more preferably below 20%, most preferably below 10%. In one embodiment the pectin is preferably characterized by a degree of amidation from 5% to 50%, preferably from 10% to 40%, more preferably from 15% to 30%, even more preferably from 15% to 25%.
- Amidation provides additional possibilities in tuning the charge or charge density on pectin and thus its interactions with collagen accordingly. In this way organoleptic and mechanical properties can be optimized. Moreover amidation can be especially advantageous for reduction of reducing the effluent COD.
- Pectin has a molecular weight distribution.
- a molecular weight distribution describes the relationship between the number of moles of each polymer species (Ni) and the molar mass (Mi) of that species.
- the molecular weight distribution can be measured by chromatography as size exclusion chromatography.
- Representative molecular weight values as the weight-average molecular weight (Mw), number average molecular weight (Mn), minimum molecular weight, maximum molecular weight, molecular weight range and/or peak molecular weight can be derived from the molecular weight distribution.
- the representative molecular weight may be expressed in Da (Dalton) or in kg/mol (kilogram / mol).
- the peak molecular weight is the molecular weight of the highest peak in the molecular weight distribution.
- the molecular weight range is the range from the minimum molecular weight to the maximum molecular weight.
- the pectin preferably has a peak molecular weight lower than 300 kDa, more preferably lower than 200 kDa, even more preferably lower than 100 kDa, even more preferably lower than 50 kDa, even more preferably lower than 25 kDa most preferably lower than 10 kDa.
- the pectin preferably has a peak molecular weight higher than 2.5 kDa, more preferably higher than 10 kDa, even more preferably higher than 25 kDa, even more preferably higher than 50 kDa most preferably higher than 100 kDa.
- the pectin has a peak molecular weight from 2.5 kDa to 300 kDa, more preferably from 5 kDa to 200 kDa, even more preferably from 10 kDa to 150 kDa, even more preferably from 10 kDa to 100 kDa most preferably from 25 kDa to 50 kDa.
- the pectin preferably has a molecular weight range from 250 Da to 1000 kDa, more preferably from 500 Da to 750 kDa, even more preferably from 500 Da to 500 kDa, even more preferably from 750 Da to 250 kDa, even more preferably from 1000 Da to 150 kDa.
- a relatively low molecular weight may improve diffusion into the leather, resulting in higher uptake, shorter processing times and optimal leather properties as mechanical strength and organoleptic properties.
- a relatively high molecular weight may improve the binding to the collagen, inducing optimal leather properties as mechanical strength and organoleptic properties.
- a relatively high molecular weight may improve the filling properties, and therefore in that way improve the organoleptic properties of the leather.
- the pectin may also be partially depolymerized pectin.
- molecular weight of the extracted pectin is reduced by cleaving part of the glycosidic linkages.
- the molecular weight distribution will change upon partially depolymerizing, represented by a lower weight- average molecular weight (Mw), lower number average molecular weight (Mn), lower peak molecular weight, lower minimum molecular weight and/or lower maximum molecular weight.
- Partial depolymerization may be induced by enzymatic treatment, acid hydrolysis, hydrothermal processing, high shear processing and/or by photo-chemical reactions.
- enzymatic depolymerization is very specific in the sense that enzymes only target specific bonds. So by enzymatic partial depolymerization the depolymerization can be optimally controlled. For example endo polygalacturonase only breaks the GalA - GalA bond in the homogalacturonan backbone.
- enzymatic depolymerization generally induce no other reactions (as for example de-methoxylation) except for the desired cleavage of the glycosidic linkage, so apart from the partial depolymerization the pectin stays intact and possible undesired side-reactions are prevented.
- enzymatic depolymerization generally takes place under mild conditions.
- the non-enzymatic methods results in either high amounts of chemical waste (acid/salt), substantial energy consumption, unspecific degradation of polysaccharides and partial breakdown of monosaccharides released. Therefore, non-enzymatic processes are usually undesired.
- Typical enzymes for partially depolymerizing pectins are pectinesterase, polygalacturonase, pectate lyase, pectin acetylesterase, b-galactosidase and arabinosidase, resulting in partially depolymerized pectin by pectinesterase, polygalacturonase, pectate lyase, pectin acetylesterase, b-galactosidase and/or arabinosidase.
- the enzymatically partially depolymerization may target a specific part of the pectin, for example the homogalacturonan (HG) backbone.
- glycosidic linkages of the pectin may be hydrolyzed or may undergo beta-elimination.
- a partially enzymatically depolymerized pectin for which the glycosidic linkages are hydrolyzed is a partially enzymatically hydrolyzed pectin.
- the pectin preferably is partially depolymerized pectin.
- the pectin is partially depolymerized pectin with a molecular weight as defined in one of the preceding paragraphs.
- the pectin is partially depolymerized pectin selected from the group of partially acid hydrolyzed pectin, partially enzymatically depolymerized pectin, partially hydrothermally depolymerized pectin, partially high shear depolymerized pectin and partially photo-chemically depolymerized pectin, more preferably the pectin is selected from the group of partially acid hydrolyzed pectin and partially enzymatically depolymerized pectin, even more preferably the pectin is partially enzymatically depolymerized pectin.
- the partially enzymatically depolymerized pectin is a partially enzymatically hydrolyzed pectin.
- the partially enzymatically hydrolyzed pectin is a partially enzymatically hydrolyzed pectin by pectinesterase or polygalacturonase or both. Partial depolymerizing results in pectin with a lower molecular weight and therefore may improve diffusion into the leather, making partially depolymerized pectin especially suitable for post tanning. A higher uptake, shorter processing times and optimal leather properties as mechanical strength and organoleptic properties are foreseeable as pectins with lower molecular weight diffuse more rapidly in the leather.
- a combination of different pectins is applied.
- a combination of different pectins that differ in structure is applied, for example partially depolymerized pectin with amidated pectin.
- the preferred pectin may be HM pectin and amidated or LM pectin and amidated; the preferred pectin may also at the same time be partially depolymerized. It will also be understood by the skilled person that depending on the circumstances, the preferred pectin may also be characterized by a certain range of degree of methoxylation and a certain range of degree of amidation and a certain range of molecular weight. It will also be understood by the skilled person that depending on the circumstances, preferably a combination of the above pectins is used.
- the pectin preferably is provided as an aqueous phase comprising pectin.
- the pectin is dissolved and/or emulsified and/or suspended and/or dispersed in the aqueous phase, resulting in an aqueous phase comprising dissolved pectin and/or an aqueous phase comprising emulsified pectin and/or an aqueous phase comprising suspended pectin and/or an aqueous phase comprising dispersed pectin or in other words resulting in dissolved pectin and/or emulsified pectin and/or suspended pectin and/or dispersed pectin.
- no preservative is present in the aqueous phase, more preferably no preservative selected from the group consisting of a biocide, a fungicide and a combination thereof is present in the aqueous phase.
- the aqueous phase comprises from 0.1 to 10 wt.% pectin, preferably from 0.2 to 5 wt.%, more preferably from 0.4 to 2 wt.%.
- the weight ratio pectin to tanned leather ranges from 0.001 to 0.1 , preferably from 0.002 to 0.05, more preferably from 0.004 to 0.02.
- vinyl polymers are employed in conventional leather manufacturing.
- Vinyl polymers are characterized by that they are obtained from vinyl monomers through addition polymerization.
- Typical vinyl polymers employed for leather are homo- or co- polymers of polyacrylate and polymethacrylate.
- Various vinyl polymer compounds have been routinely used in leather posttanning processes and are known to diffuse in the leather or to impregnate the leather.
- Vinyl polymers may be used in any of the post-tanning steps, moreover, in some case repetitive addition in different steps strengthens the effect of the vinyl polymer.
- Vinyl polymers may interact with the leather matrix through electrostatic interactions, which is generally particularly effective in the case of mineral tanned leather.
- vinyl polymers When applied during post-tanning, vinyl polymers contribute amongst others to grain appearance, evenness of dyeing, dyeing intensity, grain tightness, softness, fullness, milling pattern, evenness of milling grain and thermal stability of the crust leather.
- vinyl polymers being synthetic, toxicity and environmental issues are largely associated with a combination of their petro-chemical nature and manufacturing process. Also they are generally not biodegradable.
- leather manufacturing starts with raw hides (or furs) and generally has four stages referred to as beamhouse, tanning, post-tanning and finishing. Each stage usually has several steps. After the tanning, tanned leather is obtained, after post-tanning crust leather is obtained and after finishing finished leather is obtained. During or at the end of each step the leather may be dried to a desirable moisture content. Crust leather does not necessarily always need to undergo finishing; for some applications crust leather is directly applied in an end-product. As leather manufacturing concerns turning raw hides into material resistant to putrefaction and tanning is the essential step for this transformation, leather as understood by the skilled person is tanned leather. So in the context of the current invention leather is tanned leather. Crust leather and finished leather are consequently a form of tanned leather.
- Beamhouse operations prepares raw hides for tanning by removing all non-collagenous materials from the hides through a series of treatments that may include soaking, (green) fleshing, unhairing, liming, lime splitting, deliming, bating, degreasing and pickling.
- Tanning protects the hides from putrefaction when wet and improves the mechanical properties. Tanning transforms hides into tanned leather. During the tanning process tanning agents penetrate the hides and interact with collagen. Most commonly, hides are tanned with chromium salts, but several alternatives exist. Tanned leather tanned with chromium is often called wet-blue (WB) leather, whilst tanned leather tanned with aldehyde is often called wet-white (WW) leather.
- WB wet-blue
- WW wet-white
- the leather is wet-blue leather. In another embodiment of the invention the leather is wet-white leather.
- leather is a product that is well-known in the art. Leather may also be understood to comprise man-made materials using tissue engineering and biotechnology to produce bio-materials with composition and properties similar to natural animal made leather as for example described in US 2014/0259439.
- Tanned leather is sorted and mechanically processed (e.g. split, shaved), before post-tanning starts.
- post-tanning leather During post-tanning leather’s organoleptic properties are significantly improved and largely defined.
- the above mentioned post-tanning like tanning, is a wet process in which leather is submerged in an aqueous phase and specific components penetrate in the leather and alter its properties. In other words, the leather is impregnated with the specific components.
- Post-tanning comprises several steps that are sequentially or (partially) simultaneously performed.
- Neutralizing during neutralizing the pH of the tanned leather is adjusted.
- Retanning During retanning one or more compounds are added that diffuse in the leather and interact with collagen. Retanning among others (further) strengthens the collagen structure; improves the overall organoleptic properties such as softness and fullness; fills the loose and empty parts of the leather thus improve the evenness and general cutting value; improves buffing properties and grain appearance. Mineral retanning such as rechroming is a retanning step.
- Dyeing During dyeing a dye is added which penetrates the leather and gives the leather a uniform shade of color.
- Fatliquoring during fatliquoring an oil or fat emulsion is provided, the oil or fat penetrates the leather and interacts with the collagen fibers. Fatliquoring aims at lubricating collagen fibers, preventing the fiber structure sticking together during drying, and to render specific characteristics (e.g. organoleptic, mechanical and/or waterproof properties).
- steps may also be combined, for example neutralizing and retanning, neutralizing and dying, neutralizing and fatliquoring, retanning and dyeing, retanning and fatliquoring, dyeing and fatliquoring, retanning and dyeing and fatliquoring or neutralizing and retanning and dyeing and fatliquoring.
- steps may also be repeated, for example retanning and/or dyeing may be performed more than one time.
- crust leather After the post-tanning the tanned leather is named crust leather.
- the crust leather may undergo surface treatments called finishing. Finishing not only renders leather grain protection against water and soiling, but also determines the appearance of the final surface of the leather and the surface properties such as flexibility and handle and/or permeability.
- Mechanical operations as well as coatings can be applied through common application methods such as padding, spray coating, roller coating or curtain coating.
- contacting the leather with an aqueous phase can be understood as submerging the leather in an aqueous phase.
- contacting the leather with an aqueous phase comprising pectin is carried out for a time period that ranges from 10 to 1500 minutes, preferably from 20 to 500 minutes, more preferably from 20 to 250 minutes. In an embodiment contacting the leather with an aqueous phase comprising pectin is carried out at a temperature that ranges from 10 to 95 °C, preferably from 20 to 75 °C, more preferably from 25 to 55 °C. In an embodiment contacting the leather with an aqueous phase comprising pectin is carried out during one or more selected from the group consisting of neutralization, retanning, dyeing and fatliquoring.
- the organoleptic and mechanical properties of the leather can be tailored by applying pectin at a specific post-tanning step, at a specific temperature or during a specific time period.
- aqueous phase During post-tanning leather is in contact with an aqueous phase. Chemicals (among which polymers such as vinyl polymers and pectin) dissolved in the aqueous phase diffuse into the leather and interact with the collagen changing the leathers properties. Grain appearance, evenness of dyeing, dyeing intensity, grain tightness, softness, fullness amongst others may be altered. These organoleptic properties relate to the collagen structure and can only be altered by chemicals that diffuse into the leather. Also mechanical parameters such as tensile strength may be affected by chemicals that diffuse into the leather. As these mechanical parameters concern bulk properties of the leather, inevitably they only are altered when chemicals diffuse into the leather.
- Presence of chemicals in the leather can be demonstrated through commonly known methods as selective staining of a cross section and subsequent visual identification or through extraction from leather and chemical identification. Also a mass balance can be established over one or more post-tanning steps to establish impregnation of the leather by determining the concentration in the waste water and the total amount of waste water and comparing this with the amount added. Concentrations of organic material in the waste water may be established through COD or BOD measurement and may be related to uptake, as for example is described by Von Behr (Universal Journal of Materials Science, 6(1 ), 20-26, 2018).
- leather is impregnated with a specific chemical when a specific chemical, for example pectin is present along a cross-section of a piece of leather.
- leather is impregnated with pectin if pectin is present at a length perpendicular to the surface of a cross section of the leather of more than 5% (length/length) of the total length of the cross section measured from the surface of the cross section, more preferably 10%, even more preferably 30%.
- the leather comprising pectin comprises at least 0.1 wt.% pectin, more preferably at least 0.2 wt% pectin, even more preferably at least 0.4 wt.% pectin, most preferably at least 0.8 wt.% pectin, wherein the wt.% is calculated based on the weight of the leather.
- Leather can be characterized by its organoleptic properties, its mechanical properties and its physical properties. For all of these properties the measurement methods are known in the art (Tanning Chemistry: the Science of Leather’ (Covington), RSC Publishing (2009),‘Pocket Book for the Leather Technologist’ (Heidemann), BASF 4th edition,‘Fundamentals of Leather Manufacture’, Eduard Roether KG (1993)). Also several standardized measurement methods are common in the art. Typical organoleptic properties are grain appearance, evenness of dyeing, dyeing intensity, grain tightness, softness, fullness, milling pattern and evenness of milling grain.
- Typical mechanical properties are the maximum force (F max (N)), tensile strength (Tn (N/mm2)) and elongation at bream (Eb (%)).
- Typical physical properties are fogging behavior, formaldehyde emission, light fastness, heat yellowing and waterproofness.
- Leather or leather chemicals may also be assessed for their biodegradability by for example BOD measurement.
- Waste water generated during leather processing may be analyzed for chemical oxygen demand (COD), which is a measure for all organic material in the waste water.
- Waste water generated during leather processing may also be analyzed for biological oxygen demand (BOD), which is a measure for all biodegradable organic material in the waste water. A high ratio of BOD/COD is desired, since in that case more of the organic material in the waste stream will be biodegradable.
- Endo-polygalacturonase M2 (Aspergilus aculeatus), a pectin hydrolysing enzyme, was obtained from Megazyme. Novoshape (Novozymes) was used for the de-methoxylation of pectin.
- Novoshape is used for further de-methoxylation of sugar beet pectin SB 01 to achieve methoxylation degrees of -50% and -100% relative to the initial degree of methoxylation.
- a 10 wt. % partially enzymatically hydrolyzed pectin solution of 1500 ml_, 6 ml_ (for 100% de-methoxylation) or 100 mI_ (for 50% de-methoxylation) of Novoshape was added respectively.
- the reaction is carried out at 40°C while NaOH (2M) is used to maintain the pH at 5.2.
- 100% de-methoxylation is determined when no more NaOH is needed for pH adjustment any more, where 50% methoxylation is determined when 50% of the above consumed volume for 100% de-methoxylation has been added.
- Waste water streams of the relevant post-tanning treatments were analyzed for chemical oxygen demand (COD) according to the method ISO 15075/ISO 6060 Tubes: Macherey - Nagel.
- WB bovine leather (thickness 1-2mnn) is treated according to the basic recipe according to table 3, where 1.5 % (based on shaved weight of WB) of either unmodified citrus pectin CT 02, unmodified sugar beet pectin SB 01 or a synthetic derivate (Syntan RS 540 from Smit&zoon) is applied after mineral retanning and neutralization during the retanning process, just before the addition of phenolic retanning agents and dyestuff.
- Table 3 Post-tanning recipe of example 1.
- the resulting crust leather samples were compared to the reference, being either the crust leather sample that was treated according to table 3 with Syntan RS 540 instead of pectin or that was treated without the addition of pectin or RS 540 (blank).
- the results are listed in table 4. Both samples contribute to improvements in dyeing intensity and fullness. Softness performances vary.
- Table 4 Organoleptic assessment for example 1 (leather treated with CT 02 assessed against blank and leather treated with SB 01 against leather treated with reference Syntan RS 540).
- Wet-blue (WB)bovine leather (thickness 1-2 mm) is treated according to the recipe of table 3 modified for a shoe-upper article, where 1-2% (active matter, based on shaved weight of WB) of either partially enzymatically hydrolyzed citrus pectin CT 01 (H-CT 01 ), partially enzymatically hydrolyzed sugar beet pectin SB 01 (H-SB 01 ), or a synthetic derivate (Syntan RS 540 from Smit&Zoon) is applied after mineral retanning, after neutralization and during the retanning process just before the addition of phenolic retanning agents and dyestuff.
- WW bovine leather was treated according to the following recipe, where 1-2% (active matter, based on shaved weight of WW) of either partially enzymatically hydrolyzed, amidated citrus pectin CT 02 (H-CT 02), or an amphorteric acrylic copolymer retanning agent (reference) is applied at the beginning of retanning.
- 1-2% active matter, based on shaved weight of WW
- H-CT 02 amidated citrus pectin CT 02
- an amphorteric acrylic copolymer retanning agent reference
- COD samples are taken after applying all wet-end chemicals and after washing (table 6).
- references blank samples corresponding to effluent from WW leather treatment with the same process but without the participation of the specific components (acrylic copolymer reference or H-CT 02) are also taken.
- a blank sample is linked to a specific treated samples since it is cut from the same hide and is even a neighboring piece of the treated piece of leather.
- H-CT 02 appears to be more effective in reducing the effluent CODs.
- Table 7 COD values for example 3.
- WB bovine leather was treated according to the basic recipe used for example 1 (table 3), where 1.5% (active matter, based on shaved weight of WB) of a combination of partially enzymatically hydrolyzed citrus pectin CT 01 and partially enzymatically hydrolyzed sugar beet pectin SB 01 with varying ratios (1 :1 and 1 :2) or a synthetic derivate (Syntan RS 540 from Smit&zoon) is applied after mineral retanning and neutralization during the retanning process just before the addition of phenolic retanning agents and dyestuff.
- Table 8 Organoleptic assessments for example 4 (all samples against reference WB treated with
- Table 9 Organoleptic assessments for example 5 (all samples against reference Syntan RS 540).
- Table 12 Post-tanning recipe example 6, wet-white.
- Table 13 Formaldehyde emission and fogging, example 6
- wet-blue (WB) bovine leather was treated according to the basic recipe of table 3 for which the retanning step was modified.
- WB wet-blue
- SB bovine leather
- RS 540 phenolic syntan
- dyestuff a combination of vegetable tannin (e.g. Chesnut KPN), a water-proof retanning agent (Syntan MW 005 from Smit & zoon) and a dyestuff is applied before the application of either 0.5 - 1 wt.
- Organoleptic properties of obtained crust leather has some differences compared the reference leather obtained from treatment with traditional synthetic derivates.
- the average Maeser value (standard measurement for water-proofness according to ASTM D- 2099/ISO 5403-2) of crust leather treated with H-SB 01 according to this example is above 75.000, lower than that from leather treated with traditional synthetic derivates (which is above 130.000) but much higher than general requirements of 20.000.
- wet-blue (WB)bovine leather was treated according to a modified recipe used for Example 1 with different syntan/fatliquor combinations, where either 0.8 wt. % (based on shaved weight of WB) of partially enzymatically hydrolyzed sugar beet pectin SB 01 or a synthetic derivate as reference (Syntan RS 540 from Smit&Zoon) is applied at the end of fatliquoring and just before the final pH adjustment using formic acid.
- Table 15 Organoleptic assessments for example 8 (against reference WB treated with Syntan RS
- wet-blue (WB) tanned bovine leather (thickness 1-2 mm) was treated according to the following recipe, where either 1 wt. % (based on shaved weight of WB) of partially enzymatically hydrolyzed sugar beet pectin SB 01 or a synthetic derivate (Syntan RS 540 from Smit&zoon) is applied before mineral retanning.
- WB wet-blue
- wet-white (WW)bovine leather was treated according to the following recipe (table 18).
- the leather was treated with and without partially enzymatically hydrolyzed sugar beet pectin SB 01 (0.6 wt. % based on shaved weight of WW) and is applied at the beginning of retanning (sample 1 ) or at the end of fatliquoring (sample 2).
- Examples 1-10 were performed with pectin.
- Other acid polysaccharides may be employed as well, for example alginate, chondroitine, hyaluronic acid, heparine, fucoidan, fucooligosaccharide or carrageenan.
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CN201980029208.7A CN112041466B (en) | 2018-03-28 | 2019-03-28 | Leather treatment comprising the use of pectin |
EP19712614.7A EP3775293B1 (en) | 2018-03-28 | 2019-03-28 | Treatment of leather including employing pectin |
BR112020019690-8A BR112020019690A2 (en) | 2018-03-28 | 2019-03-28 | METHOD FOR TREATING LEATHER, LEATHER, TREATED LEATHER AND PRODUCT |
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EP2110446A1 (en) | 2008-04-18 | 2009-10-21 | C & J Clark International Limited | Tanning of hides and skins |
US20140182064A1 (en) * | 2011-06-02 | 2014-07-03 | Lanxess Deutschland Gmbh | Polysaccharide and/or polypeptide based graft polymers as synthetic tannins |
US20140259439A1 (en) | 2013-03-15 | 2014-09-18 | Itaconix Corporation | Polycarboxylic Acid Polymers For Treatment of Leather |
WO2016009387A1 (en) * | 2014-07-18 | 2016-01-21 | Universita' Di Pisa | Tanning agents |
CN106811558A (en) * | 2015-11-29 | 2017-06-09 | 青岛森美克化工技术有限公司 | A kind of preparation method of formaldehyde-free retanning agent |
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CN1128813C (en) * | 2001-01-19 | 2003-11-26 | 华北工学院 | Pectin producing method |
CN102839237B (en) * | 2012-09-28 | 2014-10-29 | 郑州科信化工有限公司 | Novel leather retanning method |
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Patent Citations (5)
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EP2110446A1 (en) | 2008-04-18 | 2009-10-21 | C & J Clark International Limited | Tanning of hides and skins |
US20140182064A1 (en) * | 2011-06-02 | 2014-07-03 | Lanxess Deutschland Gmbh | Polysaccharide and/or polypeptide based graft polymers as synthetic tannins |
US20140259439A1 (en) | 2013-03-15 | 2014-09-18 | Itaconix Corporation | Polycarboxylic Acid Polymers For Treatment of Leather |
WO2016009387A1 (en) * | 2014-07-18 | 2016-01-21 | Universita' Di Pisa | Tanning agents |
CN106811558A (en) * | 2015-11-29 | 2017-06-09 | 青岛森美克化工技术有限公司 | A kind of preparation method of formaldehyde-free retanning agent |
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WO2023062129A1 (en) | 2021-10-15 | 2023-04-20 | Coöperatie Koninklijke Cosun U.A. | Sugar beet pectin |
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BR112020019690A2 (en) | 2021-01-05 |
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EP3775293A1 (en) | 2021-02-17 |
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