Patent Application
20170159235
Not Applicable
Field of the Invention
The invention relates to methods and compositions for treating denim garments with a cellulase enzyme to impart an aged appearance.
Description of the Related Art
Denim fabric is the industry standard material used for making blue jeans. Typically, blue denim is indigo-dyed denim. As the indigo-dyed denim fabric ages through washing and wearing, it becomes softer and the color fades, with white areas becoming visible in the fabric. This texture and appearance is popular with consumers, and manufacturers of jeans have developed techniques to attempt to approximate that texture and appearance in new jeans. For example, manufacturers sometimes wash the jeans in a washing machine with stones, such as pumice stones, to produce a stonewashed look. Enzymes, including cellulases but also including other classes of enzymes, have also been used to impart a stonewashed appearance.
Commercial manufacturers often wash jeans with cellulase (also referred to as cellulolytic) enzymes, which can provide softening and also a stonewashed appearance. Cellulase enzymes act on the cellulose in the jeans, thereby releasing material and color from the jeans, producing lightened or whitened areas to provide an appearance similar to that achieved using stonewashing. The use of cellulase enzymes to stonewash jeans is disclosed in U.S. Pat. Nos. 4,832,864 and 4,912,056 to Olson, and U.S. Pat. Nos. 5,006,126 and 5,122,159 to Olson et al., the entire disclosures of which are hereby incorporated by reference. Other enzymes have also been used to impart a stonewashed look to denim, or to aid in cellulase-based enzymatic stonewashing. For example, the use of proteases to limit backstaining in a cellulase stonewashing process is described in U.S. Pat. No. 6,251,144 (Clarkson et al.). Kalum et al. (U.S. Pat. No. 6,146,428) describe the use of pectolytic enzymes in conjunction with a cellulase for enzymatic stonewashing. Vollmond (U.S. Pat. No. 5,908,472) describes the use of a cellulase in conjunction with an oxidoreductase and an enhancing agent for enzymatic stonewashing of denim.
The methods described above are conventionally used by manufacturers to treat batches of jeans. Other processes, such as bleaching with chlorine bleach, peroxides, or repeated washings using detergent, have been used by consumers to try to further fade denim. Many other techniques for imparting an aged appearance have also been used.
All of these processes, while useful to varying extents in lightening the jeans and producing both micro-variations and macro-variations (e.g., the seams generally get lightened more than other macro-regions) in color, still do not resemble a well-used pair of jeans as closely as many consumers would like. Hence, manufacturers have resorted to selling jeans that have been customized to provide a more aged appearance (e.g., by imparting crease lines near the crotch, selective fraying, crumples at the knee, etc.). This customization process is normally performed by trained experts using mechanical processes such as sandblasting, rubbing with sandpaper of files, belt sanders, laser processing, and cutting. This type of customization can be attempted at home by consumers, but it is risky as one can easily damage the jeans and/or do a poor job of providing an authentically aged appearance. Several products or kits are now available to consumers who want to “distress” their own denim garments. These systems use some type of mild bleaching action or mechanical abraders such as a pumice stone for rubbing, or emery boards.
McDevitt (U.S. patent application Ser. No. 10/277,273) describes a method to use a cellulase enzyme solution to spot-treat denim jeans, in conjunction with mechanical agitation in a home laundry setting. Unfortunately, this method often led to unpredictable damage to the fabric in the vicinity of the treated areas, thereby limiting the commercial feasibility of the method.
Numerous commercial laundry detergents contain cellulases, but in those instances, significant fading and aging of the laundered articles is not intended, as the concentration of cellulases is not sufficiently high to cause substantial fading during normal use.
There remains a need for a suitable, mild, effective method for customizing denim garments so as to provide an authentically aged appearance. There is a need for a method that can be used safely by a consumer in his or her own home to provide accelerated aging of denim garments.
The invention described herein provides methods and kits for fading and enhancing localized wear patterns of indigo-dyed denim garments. More specifically, a method is described for producing an aged appearance in denim garments comprising the steps of: 1) treating an indigo-dyed denim garment with a cellulase preparation in an aqueous solution for a period of between 15 minutes and 48 hours, (2) washing the garment, (3) mechanically abrading the garment, and (4) repeating steps 1-3 at least one additional time. In some embodiments, steps 1-3 are repeated at least two additional times, and potentially as many as 8 additional times.
Kits for fading and enhancing localized wear patterns of consumer-owned indigo-dyed denim garments are provided, comprising a package of between one and six individually packaged treatment units, each treatment unit comprising a cellulolytic enzyme, optionally formulated with one or more additional excipients such as binders, enzymes, surfactants, dissolution-enhancing agents, dyes, fragrances, wetting agents, softeners, colorants, coatings, preservatives, oxidizing agents, bleaching agents, anti-backstaining agents, encapsulants, and buffering agents. Each treatment unit is individually packaged in a unit use packaging system including, but not limited to, a blister pack, stickpack, foil pouch, disposable wrapper, or dissolvable encapsulant such as a dissolvable pouch or dissolvable capsule. In some embodiments, each treatment unit, upon dissolution in water, yields a pH between 4 and 8. Solid enzyme formulations, for example tablets, powders, and granular formulations, are advantageous because of enhanced shelf stability. Liquid enzyme formulations do not require dissolution prior to commencing enzymatic hydrolysis. Typically, the cellulase formulation comprises greater than 5,000 CMC units of cellulase activity, and preferably, greater than 10,000 CMC units of cellulase activity per individually packaged treatment unit.
In some embodiments, the first step of enzymatic treatment of the denim is performed in a washing machine, such as a home washing machine conventionally used to launder clothing, and is typically followed by the second step, the washing process, in the same washing machine, optionally including a commercial laundry detergent. The duration of the third step (i.e., mechanical abrasion) can vary. The mechanical abrasion step can be performed by tumbling (e.g., tumble-drying in a dryer, with or without heat) the denim garment for 80 minutes or more, or wearing the garment for 6 hours or more. The interval between the first treatment cycle and the second treatment cycle can range from many hours to many months. In other embodiments, the first and/or second step are performed in a tub or sink or bucket or other suitable containers.
The methods are used to produce a more authentic aged appearance than is produced by subjecting the denim garment to the same composite degree of fading at one treatment. By wearing the garment between enzyme treatments, the natural wear patterns on the denim become more accessible to subsequent enzyme treatment, and thus the enzymes preferentially attack fabric regions that are already distressed. Hence, the sequential method described herein provides a faded denim product with a more authentically aged appearance relative to an equally faded denim product wherein the enzymatic stonewashing occurs all at once, or without the apparel being worn being enzymatic treatments.
This methods are particularly useful for individuals engaged in purchasing and wearing denim garments, and is not intended for use by a manufacturer or commercial laundry prior to retail sale. Accordingly, the methods are particularly useful for consumer-owned denim garments, i.e., indigo-dyed denim garments that belong to an end user, for example, after retail purchase.
The methods can be performed on brand new denim garments, or on garments that have already been worn for which a consumer prefers a more aged appearance. The methods allow a user to accelerate and enhance the natural denim aging process.
The methods of the present invention are compatible with conventional consumer washing machines. Agitation during the enzyme treatment step enhances the extent of color fading, as does a longer treatment period. In some embodiments, during the cellulase enzyme treatment step, denim garments are run through a regular washing machine cycle, albeit using a cellulase composition rather than conventional laundry detergent. In other examples, the treatment step entails a long soak, up to 48 hours, before agitation commences, or after a brief initial agitation period. In other examples, the treatment step includes intermittent periods of agitation and soaking. In other embodiments, there is no agitation, and instead only a soaking period during the enzyme treatment step.
In typical embodiments, between 1,000 and 200,000 CMC units of cellulase are applied per kg of denim garment, wherein CMC units are measured using the method of Ghose (1987). The enzyme solution is typically diluted in the washing machine to activity levels between 100 and 10,000 CMC units per liter.
The cellulase used in the methods and kits described herein may be an acid cellulase, a neutral cellulase, or an alkaline cellulase, i.e., exhibiting maximum cellulolytic activity in the acid, neutral or alkaline range, respectively. Neutral cellulases can be advantageous relative to acid cellulases because of reduced damage to the denim garments (and potentially equipment by avoiding lower pH treatments), and can be advantageous relative to alkaline cellulases because they can be easily inactivated by laundering using conventional detergents at alkaline pH.
The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting since the scope of the present invention will be limited only by the appended claims.
As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise. Thus, for example, references to “cellulase” or “cellulase preparation” include mixtures of such cellulase enzymes, reference to “the method” includes one or more methods, and/or steps of the type described herein and/or which will become apparent to those persons skilled in the art upon reading this disclosure and so forth.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. All publications mentioned herein are incorporated herein by reference for the purpose of disclosing and describing the material in connection with which the reference was cited.
As used herein, the term “stonewash” is a process in which denim garments are contacted by pumice stones or other suitable abrasive materials, cellulase enzymes, a combination of cellulases and other enzymes, or a combination of abrasive materials and enzymes, and treated for a sufficient period of time to produce localized variations in color density.
In the present context, the term “cellulase” or “cellulolytic” enzyme refers to an enzyme which catalyses the degradation of cellulose to glucose, cellobiose, triose and other cello-oligosaccharides, and includes endoglucanases. Moreover, the term is understood to include a mature protein or a precursor form thereof, or a functional fragment thereof which essentially has the activity of the full-length enzyme, or homologues or analogues of said enzyme.
Indigo-dyed denim garments can be treated according to the methods of the invention before ever having been worn on the body, or they can be treated after having been worn. Preferred denim garments are indigo-dyed denim garments, as the ring-dyeing nature of indigo dyes leads to the characteristic fade patterns on well-worn denim garments.
The methods of the invention are useful when combined with unsanforized denim (often sold as “shrink-to-fit” denim). Unsanforized denim has not been pre-shrunk prior to consumer purchase. Instead, the denim shrinks substantially after it is initially wetted. Individuals wanting the customized fit of shrink-to-fit indigo-dyed jeans, and/or the increased roughness of unsanforized indigo-dyed denim jeans, have limited choices other than dark, non-stonewashed, indigo jeans that take a long time to fade. For individuals preferring a customized fit in a more faded pair of jeans, existing options are flawed.
According to the methods of the present invention, for the cellulase treatment step, the following elements are introduced into a suitable container, for example a home washing machine, in any order: (i) a cellulase formulation, (ii) one or more indigo-dyed denim garments, and (iii) water. Additional elements (e.g., buffers or softeners) may be added. The garments are soaked and/or agitated for a period of 15 minutes to 48 hours.
The amount of cellulase formulation used to treat the garments depends on the size of the garments, the activity of the enzyme, and the extent of abrasion desired. That said, the total activity of the cellulase formulation used according to the methods and kits of the invention is significantly larger than the total activity of cellulases used during laundering with commercial laundry detergents. For example, cellulase formulations used according to the methods of the invention, when agitated for 15 minutes at 40 degrees Celsius, have sufficient cellulase activity to lighten a pair of previously washed indigo-dyed denim jeans, as measured by the CIELAB L value, by at least 0.5 units when averaged across different regions. In some embodiments, cellulase activity is sufficient to lighten said jeans by a least 1.0 unit. In typical embodiments, CMC activity per gram of the cellulase compositions of the kits described herein exceed 200 CMC units per gram, and typically comprise at least 10,000 units CMC activity per each packaged cellulase treatment unit within a kit. In contrast, for example, Knorr et al (U.S. Pat. No. 6,235,697, assigned to Colgate-Palmolive) describe a laundry detergent having cellulase activity between 0.5 and 100 CMC units per gram of detergent composition, most preferably between about 1 to 10 CMC units per gram laundry detergent.
Typically, when a home washing machine is used to perform the methods described herein, the garments are agitated in the washing machine in an amount of water corresponding to the amount automatically added to run the “low”, or “very low”, or equivalent cycle of the washing machine, although more water can be used. In order to maximize the cost-effectiveness of the treatment, the duration of treatment in the washing machine (i.e., the combined time of mechanical agitation and soaking, prior to rinsing) should be at least 15 minutes, sometimes greater than one hour. In some embodiments, the soaking period is at least 24 hours.
Subsequently, in the second step, i.e., the washing step, the denim garment is washed. In some embodiments, this step is performed in a conventional washing machine and often directly following the treatment step. The purpose of the washing step is to remove and/or deactivate the cellulase used during the treatment step. Rinsing the garment by removing the cellulase solution of the treatment step, followed by addition of water and rinsing away the water, constitutes one method of performing the washing step. In some embodiments, multiple rinsing steps are contemplated. In some embodiments, a detergent, oxidizing agent, buffering agent, or other chemicals are added during the washing step to inactivate any residual enzyme. In other embodiments, the washing step is performed at an elevated temperature sufficient to inactivate residual enzyme.
Subsequently, in the third step, the denim garment is mechanically abraded, either by (i) mechanically tumbling for a period of time exceeding 80 minutes, or 90 minutes, or 120 minutes or (ii) wearing the denim garment for a period of 6 or more hours, over a time span of 6 hours to one year, or some combination thereof. During the period of time in which the mechanical abrasion step is performed, the denim garment may be laundered. For example, a pair of jeans could be worn, laundered, dried, and worn again during this third step of the cycle. Wearing the garment facilitates natural fading patterns, and is generally preferable, if worn for sufficient periods, relative to mechanically tumbling the denim garment. When the garment is mechanically tumbled, it can be tumbled using hot air or ambient air, and can be tumbled, for example, in a residential clothes drying machine.
Finally, these steps of treating, washing, and mechanically abrading are repeated one or more times, including up to eight additional cycles.
The denim garments can be laundered prior to the initial cellulase treatment, and can be worn prior the initial cellulase treatment.
The optimum temperature of treatment depends on the particular enzyme used. Depending on the starting temperature and the ambient air temperature, the temperature of the water in the washing machine tends to drop during treatment, particularly if hot water is used. Typical temperatures at which the cellulase treatment is performed range from 10° C. to 70° C., more typically between 20° C. and 60° C.
For treatment of a single indigo-dyed denim garment (e.g., a pair of jeans), a desirable liquid to solids ratio is between 2:1 and 200:1 on a weight basis, typically between 8:1 and 100:1. In order to maximize the extent of fading, it can be preferable to extend the contact time. Providing agitation also increases the extent of fading.
For example, in one embodiment, a 0.9 kg pair of denim blue jeans is contacted with a cellulase formulation according to the methods described herein, with or without agitation. The indigo-dyed denim jeans is introduced into a home washing machine along with a single tablet of a cellulase formulation comprising 50,000 CMC units of a neutral cellulase, along with additives, including buffer salts that set the pH of the resulting solution close to the pH optimum of the cellulase, e.g., from about pH 4.5 to about pH 9, depending on the cellulase. The “low” cycle of the machine is used with hot water, and the jeans are alternatively agitated and soaked, with no rinsing, for a period of about one hour. After an hour, the jeans are rinsed and/or optionally laundered using a conventional laundry detergent.
Commercial launderers typically perform an enzymatic stonewashing process at a liquids:solids ratio (w/w) of less than or equal to 10. Typically, the methods of the present invention are performed at a higher liquids:solids ratio than 10 because of the ratio between the weight of water added in a typical “small” load setting of a residential top loading washing machine to the weight of one or two pairs of denim jeans. While a user could simply add water to the washing machine, it is generally more convenient to use the washing machine settings.
The quantity of cellulase that is used to treat the denim garments can vary greatly, depending on: the activity of the particular enzyme, the concentration of the cellulase enzyme in the cellulase formulation, and the amount of fading that is desired. Betwen 1,000 and 200,000 CMC units of cellulase are utilized per kg of denim garment, wherein CMC units are measured using the method of Ghose [Ghose, T. K. “Measurement of Cellulase Activities”, International Union of Pure and Applied Chemistry, vol. 59, No. 2, pp. 257-268 (1987)], more preferably between 5,000 and 200,000 CMC units per kg of denim garment. The cellulase formulation can be a solid, liquid, or gel. After mixing with water, the resulting enzyme solution (e.g., in a washing machine) typically has activity levels between 100 and 20,000 CMC units per liter, preferably between 1,000 and 19,000 CMC units per liter. Another cellulase activity assay is o-Nitrophenyl-β-D-cellobioside neutral units (NPCN units). In certain embodiments, greater than 1,000 NPCN units are used per enzyme treatment. In other embodiments, greater than 40 NPCN units are used per liter of solution during an enzyme treatment. In preferred embodiments, cellulolytic enzyme compositions having activity exceeding 4,000 NPCN units are used to perform the cellulase treatment.
In some embodiments, the cellulase formulation contains buffer salts to establish and maintain the pH at a level close to the pH optimum of the particular cellulase in the formulation. For example, in one embodiment, citric acid and dibasic sodium phosphate are added to establish a pH around 6.8. In some embodiments, the buffering capacity is intentionally limited to provide some buffering but also to allow the pH to drift upwards over the course of treatment (by equal to or greater than 0.2 pH units but less than 1 pH unit), thereby providing a check on enzymatic over-activity and decreasing potential damage to denim garments. For example, a citric acid/sodium citrate buffer can be used that provides an initial pH of 6.8, rising to 7.2 over the course of treatment.
Other additives can also be included in the cellulase formulation, including but not limited to binders, other enzymes, surfactants, dissolution-enhancing agents, dyes, fragrances, wetting agents, softeners, colorants, coatings, preservatives, oxidizing agents, bleaching agents, anti-backstaining agents, and encapsulants. In some embodiments, sodium percarbonate is added as an in situ source of peroxide.
The enzyme formulation may include a softening agent. Organic cationic softeners or silicone-based products can be used, but anionic or non-ionic softeners are also useful. Examples of useful softeners are polyethylene softeners and silicone softeners, i.e., dimethyl polysiloxanes (silicone oils), H-polysiloxanes, silicone elastomers, aminofunctional dimethyl polysiloxanes, aminofunctional silicone elastomers, and epoxyfunctional dimethyl polysiloxanes, and organic cationic softeners, e.g., alkyl quaternary ammonium derivatives.
A surfactant can be included in the cellulase formulations of the kits. The surfactant can increase the wettability of the aqueous solution, thereby promoting the activity of the cellulase enzyme in the fabric. The surfactant increases the wettability of the enzyme and fabric.
In some kits, the cellulase and other additives are packaged within a water-soluble shell that dissolves upon exposure to the water in the washing machine. For example, the water-soluble shell can be a flexible pouch. Such formulations comprising cellulases are advantageous because they provide for simple and easy handling of the product, enhancing safety and convenience for end-users. Suitable pouches can be made from a water-soluble polymer such as polyvinyl alcohol (PVOH). Alternative water-soluble materials include: water-soluble polyurethanes, such as polyvinylpyrrolidone (PVP); PVP copolymers, for example, vinyl pyrrilidone/vinyl acetate copolymers, such as PVP/vinyl acetate; water-soluble acrylic acid copolymers and their esters and salts, for example, the partial ester copolymers of acrylic/methacrylic acid and a polyethylene glycol ether of a fatty alcohol; organic and inorganic salts of phenylbenzimidazole sulfonic acid (PSA), such as TEA-phenylbenzimidazole sulfonate and sodium phenylbenzimidazole sulfonate; water-soluble cellulosics, such as hydroxymethylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose; water-soluble quaterniums, such as polyquaternium-7, polyquaternium-10, polyquaternium-37; carboxyvinyl polymers, such as carbomers and their salts, for example, sodium carbomer; and water-soluble polysaccharides, such as polydextrose and glucan. Alternatively, the water-soluble shell can be a rapidly-dissolving capsule such as are widely used for pharmaceutical products. Suitable capsules include capsules made from animal proteins (e.g., gelatin) and polysaccharides (including plant polysaccharides and modified polysaccharides such as hydroxypropyl methylcellulose).
Alternatively, the cellulolytic enzymes, optionally formulated with one or more additional excipients selected from the groups consisting of binders, enzymes, surfactants, dissolution-enhancing agents, dyes, fragrances, wetting agents, softeners, colorants, coatings, preservatives, oxidizing agents, bleaching agents, anti-backstaining agents, encapsulants, and buffering agents, can be packaged in unit-dose form in a blister pack, stickpack, foil-pack, or any other type of suitable unit packaging. For example, a solid cellulase formulation can be compacted into a tablet, packaged in a sealed plastic wrapper, and one or more such formulations can be provided in the kits.
Alternatively, the cellulase formulations, whether solid or liquid, can be provided without unit dosing packages. For example, a granular cellulase formulation could be provided and used according to the methods described herein, with a user simply taking a selected amount of the formulated enzyme for each treatment cycle.
Unit dosing packages provide the advantage of added convenience, and reduced consumer exposure to the cellulase enzymes and additives, thereby reducing risk of sensitization and allergic reactions. Detergent enzymes are known to cause sensitization in some people, and the cellulolytic enzymes used in the methods and compositions described herein are at much higher concentrations than those used in traditional laundry detergents. Given the enhanced risk of sensitization, it is preferable that consumers not be exposed to significant dust, and preferably minimize skin contact with the cellulase compositions (e.g., by measuring out a powder, or handling a tablet). Accordingly, a unit dose and formulation that reduces or eliminates consumer exposure during use is advantageous, as can be provided by, for example, blister pack, foil pack, flexible pouches, and stickpack packaging.
Preferably, the methods are performed using a suitable kit for fading and enhancing localized wear patterns of consumer-owned indigo-dyed denim garments, comprising a package of between one and six individually packaged treatment units, each treatment unit comprising a cellulolytic enzyme, optionally formulated with one or more additional excipients selected from the groups consisting of binders, enzymes, surfactants, dissolution-enhancing agents, dyes, fragrances, wetting agents, softeners, colorants, coatings, preservatives, oxidizing agents, bleaching agents, anti-backstaining agents, encapsulants, and buffering agents, wherein each treatment unit of cellulolytic enzymes is individually packaged in a unit use packaging system, for example, a blister pack, foil pack, stickpack, or dissolvable encapsulant such as a dissolvable pouch or dissolvable capsule.
In some embodiments, each treatment unit of said kit is formulated such that, upon dissolution in water, it yields a pH between 4 and 8. In some embodiments, each treatment unit of said kit comprises a cellulolytic enzyme formulation having greater than 5,000 CMC units of cellulase activity, or greater than 50,000 CMC unites of activity, or greater than 1,000 NPCN units of activity, or greater than 4,000 NPCN units of activity, or greater than 7,000 NCPN unites of activity. In some embodiments, each treatment unit of said kit is formulated such that, upon dissolution in water, it yields a pH between 6 and 7.5.
In a representative example, a kit for accelerated aging of indigo-dyed denim garments is provided containing a set of two individually packaged cellulase formulations, each of which comprises 10 g 2-(carbamoylmethylamino)ethanesulfonic acid as a buffer and 7.5 g of a neutral cellulase with a minimum activity of 4,800 total NPCN units, formulated as granules, each of said cellulase formulations packaged in a suitable stickpack. Any other suitable buffer system is acceptable, including, for example, buffers based on citrates, phosphates, or acetates.
Any type of residential washing machine is suitable for practicing the methods of this invention. Top-loading and front-loading machines are contemplated. In general, washing machines suitable for practicing the method of this invention have advertised clothing capacities of 30 kg or less, with volume capacities of less than eight cubic feet. Alternatively, the methods can be performed in any container that holds water, including a bathtub, sink, or bucket. Agitation can be provided with manual stirring, or any other method.
When the methods are performed in a washing machine, use of a soak cycle, with agitation followed by a soaking period, provides protection against an unintentional early rinse cycle that washes away the enzyme. Use of a regular wash cycle entails a rinse step, and thus, in the absence of an abnormally lengthened wash cycle, it can be desirable to interrupt the cycle prior to the rinse step in order to extend the contact time between the enzyme and the denim garment. There is no upper or lower time limit for practicing the method of this invention; however, treatment time in the washing machine of less than five minutes does not provide cost-efficient use of the enzymes, as enzymatic hydrolysis will be limited. Using a low dosage of cellulase and extending the treatment cycle can provide a cost-effective method of general fading of the garment, although it is not tremendously time-efficient. After sufficient time and/or mechanical agitation to develop suitable fading, the enzyme should be rinsed from the denim garment using the rinse cycle of the washing machine or via subsequent laundering. The denim garment can be removed from the washing machine prior to the rinse cycle, and the enzyme solution could be rinsed off in alternative ways or the enzyme could be deactivated using methods known in the art (e.g., heat, bleach).
CIELAB is a three-dimensional color space specified by the International Commission on Illumination. It describes all the colors visible to the human eye and was created to serve as a device-independent model to be used as a reference. The lightness is represented by L, varying from the darkest black at L=0 to the brightest white at L=100. The methods of the invention cause a lightening of the denim color, leading to an increase in L and a positive value of ΔL. In some embodiments, the cellulase treatment step provides an increase in the colorimetric L value of at least 0.5 units per cycle averaged across various locations of a denim garment for at least two consecutive treat/wash/wear cycles. In some embodiments, the cellulase treatment step provides an increase in the colorimetric L value of at least 1.0 units per cycle averaged across various locations of a denim garment for at least two consecutive treat/wash/wear cycles. In some embodiments, the treat/wash/wear cycles yield significantly greater overall fading (as measured by ΔL values) in fabric areas that tend to have greater wear (e.g., upper thigh, knees, seams) relative to fabric areas that tend to have reduced wear (e.g., mid-shin). The term atari is used to describe enhanced fading that occurs on frequently rubbed or creased areas of denim jeans. In some embodiments, this enhanced fading of the high-wear areas produced by the methods described herein yields an atari value (per cycle) of greater than 0.5 for at least two consecutive treat/wash/wear cycles, wherein the atari value is calculated as the average of ΔL values in a high-wear area minus the average of ΔL values in a low-wear area. In some embodiments, this enhanced fading of the high-wear areas yields an atari value of greater than 1.0 for at least two consecutive treat/wash/wear cycles, wherein the atari value is calculated as the average of ΔL values in a high-wear area minus the average of ΔL values in a low-wear area.
Additionally, the cyclical nature of the treatment methods allows a gradual enhancement of fading and aged appearance, allowing a customer to develop a degree of comfort with the process, facilitating more precise fine-tuning of the fading process, and reducing the likelihood of over-exposure to aggressive cellulase enzymes that could damage a garment.
The cellulase or endoglucanase may be an acid, a neutral or an alkaline cellulase, or an endoglucanase, or combinations thereof.
Accordingly, a useful cellulase is an acid cellulase. Representative embodiments are fungal acid cellulases. Preferable fungal cellulases can be derived from or produced by fungi from the group of genera consisting of Trichoderma, Actinomyces, Myrothecium, Aspergillus, or Botrytis, in particular Trichoderma viride, Trichoderma reesei, Trichoderma longibrachiatum, Myrothecium verrucaria, Aspergillus niger, Aspergillus oryzae, or Botrytis cinerea.
Another useful cellulase or endoglucanase is a neutral or alkaline cellulase. Neutral cellulases can minimize backstaining of indigo. Representative embodiments are fungal neutral or alkaline cellulases, which are derived from or producible by fungi from the group of genera consisting of Aspergillus, Penicillium, Myceliophthora, Humicola, Irpex, Fusarium, Stachybotrys, Scopulariopsis, Chaetomium, Mycogone, Verticillium, Myrothecium, Papulospora, Gliocladium, Cephalosporium and Acremonium, including Humicola insolens, Fusarium oxysporum, Myceliopthora thermophila, or Cephalosporium sp., notably from the group of species consisting of Humicola insolens, DSM 1800, Fusarium oxysporum, DSM 2672, Myceliopthora thermophila, CBS 117.65, or Cephalosporium sp., RYM-202.
Use of cellulases with high activity at neutral pH (between pH 6 and pH 8) can be advantageous, as fabric damage can be reduced at neutral pH relative to enzymatic treatment at more acidic pH, reducing the likelihood of generating holes or fabric weakness leading to holes in high-stress areas (e.g., crotch seams). Moreover, operating at neutral pH is less likely to damage washing machine equipment (e.g., rubber seals).
In one embodiment of the invention, multiple cellulases are used. In another embodiment of the invention, a cellulase comprising one or more cellulose-binding domains is used.
Commercial laundry detergents often use alkaline cellulases, which are effective at the high pH of laundry detergents. The cellulase concentration and activity is much lower in laundry detergents than the cellulase concentrations and activities of the methods of the invention.
In another embodiment of the invention, the cellulase solution also includes enzymes from other classes, such as proteases or pectinases, which can reduce backstaining. The invention also contemplates using cellulases in conjunction with amylases, glycosidases, lipases, esterases, and oxidoreductases.
In some embodiments, it is desirable to protect certain regions of the denim garments from cellulase digestion, for example, to improve atari, or to protect an area susceptible to damage, or to prevent further lightening of a given region. In these embodiments, prior to the cellulase treatment step, a protective coating is applied. The protective coating can be applied purely for aesthetic purposes (e.g., to enhance atari and/or furnish a pattern showing less faded areas against more faded areas), to enhance durability (e.g., by applying the protective coating at garment areas more likely to develop holes), or a combination thereof. For example, a protective coating could be applied around and along the crotch seams of a pair of blue jeans (often the site of deleterious holes in blue jeans), in addition to the corners of the back pockets.
Traditional laundry starch is ineffective as a protective coating, as it tends to rinse off under the conditions of the treatment step, and itself may be digested by some cellulases. However, other polymers, including both man-made and naturally occurring polymers, can in some cases reduce cellulase activity on fabric areas to which they are applied. For example, a modified potato starch that is not readily washed off denim in hot water, but is removed in hot water under alkaline conditions (e.g., as occurs during conventional washing with detergents), can be useful for reducing cellulolytic activity in regions to which the starch is applied. In such cases, the protective polymer is selectively applied, then the cellulase treatment step is performed, followed by a washing step which includes detergent and removes the protective polymer. In other embodiments, the protective polymer survives both the cellulase treatment step and the washing step.
In other embodiments, the protective coating applied to the denim is a protective wax, which can be applied to one or both sides of the denim fabric. For example, an animal wax (e.g., beeswax, lanolin), plant wax (e.g., soy wax, carnauba wax), mineral wax, petroleum-derived wax (e.g., paraffin wax), or mixtures thereof, optionally including additional agents, can be applied to the denim garment by rubbing, spraying, ironing, or other means. Depending on the wax composition and the treatment conditions, the wax composition can remain entirely or significantly in place during the cellulase treatment step. Subsequently, the protective wax composition is partly or wholly removed during the washing step, particularly when conventional laundry detergent is used during the washing step. In some embodiments, a solid white composition of plant and/or animal waxes are rubbed into the denim fabric at specific, high-stress locations on the denim garment. In other embodiments, the wax composition is applied in a pattern prior to each cellulase treating/washing/mechanically abrading cycle, resulting in a visually appealing pattern of darker, less faded portions against a more faded background. In some embodiments, a protective wax composition applied prior to a treat/wash/abrade cycle is no longer visually present at the conclusion of the wash cycle. In such cases, the protective wax composition would need to be re-applied prior to each cycle in order to maximize the protective value.
The examples that follow are intended in no way to limit the scope of this invention but instead are provided to illustrate representative embodiments of the present invention. Many other embodiments of this invention will be apparent to one skilled in the art.
A pair of men's indigo-dyed, denim jeans (Levi's® 501 shrink-to-fit jeans) was purchased, soaked in hot water and then worn while drying to provide a proper fit. The jeans were subsequently treated with neutral cellulase (IndiAge® NeutraFlex, available from DuPont) in a home laundry machine. The neutral cellulase was formulated with buffer salts (citric acid and sodium phosphate dibasic), and the cellulase preparation (12 g total, including fillers and buffered to pH 6.8, total NPCN units of at least 4,800) was added to the denim jeans in the washing machine while the washing machine filled with warm water (approximately 40° C.) on the soak cycle at the “very low” setting, corresponding to about 25 L of water. After the water fill level was reached, agitation commenced for roughly two minutes, followed by soaking for 4 hours, following by a wash cycle including agitation (14 minutes) and rinsing steps. The treated denim jeans were then laundered in the washing machine using a conventional laundry detergent, then tumble-dried. The jeans were subsequently worn for approximately 10 hours. The jeans were subjected to two additional treating/washing/mechanically abrading cycles, all performed within the timespan of one week.
These cellulase-treated jeans were compared to a pair of otherwise identical jeans, which were worn for a total of approximately 150 hours over a two-month period.
The appearance of the two pairs of jeans was compared, and the jeans treated according to the methods of the invention compared favorably to the jeans that were not cellulase-treated (see
Desized, indigo-dyed denim fabric was sewn into squares of approximately 7 inches. The denim squares were subjected to different treatments consisting of one or more of (i) a treatment step with a cellulase formulations, (ii) a washing step, and (iii) a mechanical abrasion step comprising tumbling for 30 minutes with hot air, and 60 minutes with ambient air. The cellulase treatment step comprised: (i) introducing fabric into a washing machine, along with pH 6.9 buffer and 5.5 g of a solid neutral cellulase (IndiAge® NeutraFlex) and (ii) adding approximately 25 L of water and soaking the fabric for 1 hour, with two short periods of agitation, followed by subjecting the fabric to a “heavy-duty” washing machine cycle using the same washing solution (15 minutes agitation, followed by rinsing and spinning) The washing step comprised subjecting the fabric to a standard washing machine cycle using a conventional laundry detergent. The mechanical abrading step, which also was a particularly useful simulated wearing step given the small size of the fabric samples, comprised 30 minutes of tumble drying at high heat, followed by 60 minutes tumble drying without heat.
Table 1 below shows the experimental protocol to which the various denim squares were subjected. All squares were initially subjected to a single washing step prior to commencing the experiment, and thus the table headings can be interpreted as the number of such steps after the initial washing step. The Control Sample was not subjected to any additional treatment, and was used as the reference sample to provide color difference measurements. Sample 1 was subjected to a four cycles of washing/abrading, with no cellulase treatment step. Sample 2 was subjected to a single cellulase treatment, followed by four cycles of washing/abrading. Sample 3 was subjected to two complete cellulase/wash/abrade cycles, followed by two wash/abrade cycles. Sample 4 was subjected to three complete cellulase/wash/abrade cycles, followed by one wash/abrade cycle. Sample 5 was subjected to four complete cellulase/wash/abrade cycles.
After completion of all steps, the fabric squares were subjected to colorimetry measurements using an iWave portable colorimeter to provide colorimetric Lab values. The L scale is a measure of the darkness of the sample, and positive ΔL values indicate that a sample has become lighter than the reference sample. The control sample was sampled in over ten places to obtain an average reading, and sampled further until a single reading was obtained with an L value within 0.1 units of the average L value, and that reading was used as the reference value (L=20.03, a=1.09, b=−11.16). Relative to the control (reference) sample, ΔL values at ten randomly selected spots in the center portion of each denim sample were obtained, and averaged to provide the ΔLcenter readings in Table 1. Relative to the same control sample value, ΔL values were then obtained along the sewn fabric seams, which had enhanced fading. Each sample had a wide seam of approximately one inch, in addition to smaller seams. Along the wide seam, the five most prominent ridged areas were sampled, three measurements each, and the largest of the three ΔL values measured along each ridge was recorded. Along the adjacent seam (i.e., the east seam if the wide seam is oriented north), a series of five sets of three data points each was measured along the length of the seam, and again, the largest ΔL values were recorded from each set of three measurements. Hence, five values were obtained along each seam, which generally showed enhanced fading relative to the central portions of the fabric. The average of these ten values was computed to provide ΔLseam readings. In general, the colorimetric readings along the seams showed higher ΔL values than in the center of the fabric samples, corresponding to increased whiteness. Finally, the ΔLcenter value for each fabric was subtracted from the ΔLseam value, thereby obtaining a measure of the contrast for each sample, referenced in Table 1 as the atari seam score. A higher atari seam score is desirable, and shows enhanced contrast, while a high ΔLcenter score shows enhanced lightness. Note that another way to obtain a quantified measurement for atari would be to assess the differences between local maxima and local minima, which would better highlight the differences between samples, but measurement error would be much higher.
Sample 1, subjected to 4 wash/abrade cycles without any enzyme treatments, showed very modest fading relative to the Control Sample, with minimal atari. This is analogous to buying a new pair of minimally stone-washed jeans, and going through several cycles of laundering the jeans with a detergent, wearing them a couple of times, and then repeating the cycle. Even through 4 wash-wear cycles, the fading is minimal, and the atari is very limited. This scenario is well-known to wearers of indigo-dyed denim jeans.
Sample 2, which was subjected to a one-time cellulase treatment, followed by four wash/abrade cycles, yielded results comparable to traditional store-bought, lightly stone-washed jeans; that is, a modest degree of overall fading, but the fading was fairly homogeneous, with very little atari, i.e., little variation to highlight wear patterns.
Sample 3 was subjected to two cellulase/wash/abrade cycles, followed by two additional wash/abrade cycles, showed enhanced fading relative to Sample 2, as would be expected based on the additional cellulase treatment cycle. Moreover, Sample 3 also showed enhanced atari relative to Samples 1 and 2. The same pattern was repeated with Sample 4, which was subjected to three treatment/wash/abrade cycles, followed by one additional wash/abrade cycle.
Sample 5, consisting of four treatment/wash/abrade cycles, showed the greatest overall fading, and importantly, the highest overall atari seam score. The fading in the high-abrasion areas was much greater than fading in the center, providing tremendous atari, and an overall appearance resembling a naturally faded denim garment.
This remarkable contrast is easily observed in
Importantly, the cellulase enzyme preferentially degraded areas of the fabric that were already worn, damaged, abraded, and/or faded. Conceptually, this makes sense, as, without wishing to be bound by theory, there can be greater exposed surface area in more damaged fabric regions, providing more opportunity for cellulases to act on the cellulose fibers. Accordingly, the result is that the cellulase enzymes preferentially attack already faded areas, thereby enhancing atari and natural fade patterns. Therefore, the methods of the invention constitute a novel and non-obvious method to accelerate natural aging patterns in denim garments, and provide a rapid route to an authentically aged appearance in denim garments.
An additional sample (Sample 6) of the same denim was treated with 4 cellulase treatments and wash cycles without any mechanical abrading cycles. This provided a point of comparison to Sample 5 above—both samples had identical cellulase treatments and wash treatments, but Sample 6 lacked the mechanical abrasion treatments to which Sample 5 was subjected.
Three samples of denim from the same fabric bolt were subjected to 4 cycles of cellulase treatment, washing with detergent, and mechanical abrasion. Before each cycle, one of the samples (sample A) was rubbed on both sides with soy wax (and other additives) to form a visible coating. Before each cycle, a second of the samples (sample B) was rubbed with a composition comprising beeswax and plant wax (as well as other additives). The control sample C was not wax-treated. After four cycles, the treated areas in sample A and sample B were substantially darker (e.g., ΔL>5), with less abrasion, than sample C or areas on samples A and B that had not been treated. There was a small but visible amount of backstaining that undoubtedly contributed to this retained darkness, but much of the retained color was a result of reduced cellulase enzyme activity on the wax-treated areas.
All publications, patents, and patent applications cited herein are hereby expressly incorporated by reference in their entirety and for all purposes to the same extent as if each was so individually denoted.
While specific embodiments of the subject invention have been discussed, the above specification is illustrative and not restrictive. Many variations of the invention will become apparent to those skilled in the art upon review of this specification. The full scope of the invention should be determined by reference to the claims, along with their full scope of equivalents, and the specification, along with such variations.
The present application claims priority under 35 U.S.C. §119(e) to (i) U.S. Provisional Patent Application No. 62/288,236, filed Jan. 28, 2016, and (ii) U.S. Provisional Patent Application No. 62/262,480, filed Dec. 3, 2015. The disclosures of these applications are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62288236 | Jan 2016 | US | |
| 62262480 | Dec 2015 | US |
