How to identify recycled cashmere

Abstract

To provide a method for identifying recycled cashmere, which can evaluate recycled cashmere from physical and chemical aspects.SOLUTION: A method for identifying recycled cashmere includes obtaining at least a percentage of damaged cashmere determined by microscopy (K1) and a Cashmere Genuine Index (CGI) (K2) determined by animal hair peptide analysis as explanatory variables; using a model formula obtained from multivariate analysis with an objective variable being T (where T is a real number other than 0) for new cashmere and -T for recycled cashmere; and identifying whether or not the cashmere to be identified is recycled cashmere.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method for discriminating recycled cashmere that can evaluate recycled cashmere from physical and chemical aspects.

Background Art

[0002] In recent years, apparel products are required not only to improve functionality but also to consider reducing environmental impact and clothing loss for the realization of a sustainable society. Even in the case of animal hair fibers, there are problems such as animal exploitation such as mulesing wool and rough shearing, or the expansion of deserts due to grazing. As a countermeasure, some companies are taking measures such as banning the handling of unused animal hair.

[0003] Cashmere is one of the animal hair fibers. Cashmere has long been popular as a luxury fiber due to its rarity. However, the cashmere goats that produce cashmere greedily eat grass, damage the soil with their sharp hooves, and accelerate the desertification of grasslands. Therefore, it is desirable from the perspective of reducing environmental impact to utilize not only unused new cashmere but also processed or used recycled cashmere.

[0004] Non-Patent Document 1 discloses a method for discriminating recycled cashmere that utilizes statistical processing. In Non-Patent Document 1, first, the characteristics of recycled cashmere fibers are classified into three types: (1) damage in the vertical direction, (2) damage in the axial direction, and (3) fibers cut short. A model formula is obtained by multiple regression analysis using these as explanatory variables, and this model formula is used to discriminate recycled cashmere.

Prior Art Documents

Non-Patent Documents

[0005]

Non-Patent Document 1

[0006] Establishing traceability standards is the mainstream approach to managing animal hair fibers. When attempting to quantitatively evaluate regenerated cashmere, we tried applying the discrimination method described in Non-Patent Document 1. However, this method focuses only on the physical damage to the regenerated cashmere and cannot be said to objectively evaluate it. In fact, even using the model formula shown in Non-Patent Document 1, we were unable to clearly distinguish between new cashmere and regenerated cashmere. Therefore, a more objective (quantitative) method for evaluating regenerated cashmere is needed.

[0007] The object of the present invention is to provide a method for identifying regenerated cashmere that can evaluate regenerated cashmere from physical and chemical perspectives. [Means for solving the problem]

[0008] In order to evaluate recycled cashmere more objectively, the inventors investigated the effects of physical damage to recycled cashmere. Fibrous recycled cashmere is produced by cutting products or fabrics containing cashmere and opening the fibers using a napping machine. The inventors focused on the fact that the properties of cashmere change due to physical effects such as fiber breakage, reduction of fiber strength, fiber damage, and inclusion of non-cashmere fibers during opening in the napping machine. Since recycled cashmere shows physical damage, the inventors investigated whether the nature of the damage (for example, the percentage of cashmere showing damage in shape, the percentage of fibers below a certain length, etc.) could be used to distinguish recycled cashmere. However, even by focusing only on the physical effects of recycled cashmere, it was not possible to find a clear boundary that could distinguish recycled cashmere from new cashmere.

[0009] Therefore, the inventors investigated the effects of chemical damage on recycled cashmere. Cashmere is an animal hair fiber and is mainly composed of protein. When manufacturing products and fabrics containing cashmere, it is common to decolorize and dye them from the perspective of adding value to the product. However, in the decolorization and dyeing process, the properties of cashmere change due to chemical effects such as scale dissolution, changes in the shape of the fiber surface, and alteration of proteins. The inventors focused on the fact that the properties of cashmere change due to these chemical effects and investigated whether this could be used to distinguish recycled cashmere. In other words, they investigated whether it would be possible to find some kind of boundary that can accurately distinguish recycled cashmere from new cashmere by combining the physical and chemical effects that recycled cashmere inherently possesses as a processing or manufacturing history.

[0010] To objectively (quantitatively) evaluate regenerated cashmere and new cashmere, the inventors considered that introducing statistical processing would be effective. Specifically, after diligent research to solve the aforementioned problem, the inventors discovered that by utilizing multivariate analysis with the percentage of damaged cashmere (K1), determined by microscopic methods, and CGI (also called the cashmere pure index, K2), determined by animal hair peptide analysis, regenerated cashmere can be evaluated more objectively, thus completing the present invention.

[0011] In other words, the method for identifying recycled cashmere according to the present invention has the following main points. [1] A method for determining whether the cashmere to be identified is regenerated cashmere or not, using a model equation obtained from multivariate analysis, in which the explanatory variables are the percentage of cashmere showing damage as determined by the microscopic method specified below (K1) and the CGI as determined by the animal hair peptide analysis specified below (K2), and the dependent variable is T (where T is a real number other than 0) for new cashmere and -T for regenerated cashmere. <Microscopy> Cashmere is identified using optical microscopy according to JIS L 1030-2 7.7.1 at a magnification of 100x to 500x. The shape of the cashmere fibers is identified and they are distinguished into "normal cashmere" and "cashmere with damage to its shape (crushed, torn, or frayed)." Identification and distinction are carried out sequentially until the total number of fibers reaches 1000 or more. The percentage of "cashmere with damage" is calculated using formula (1). Percentage of cashmere showing damage (%) = Total number of cashmere showing damage (pieces) / Total number of cashmere measured (pieces) × 100 … (1) <Animal Hair Peptide Method> Animal hair peptide analysis of cashmere-containing samples is performed in accordance with ISO 20418-2 Peptide detection using MALDI-TOF MS. If the sample contains wool, the Cashmere Genuine Index (CGI) is calculated using formula (2). If the sample does not contain wool, the animal hair peptide analysis is performed on a sample mixed with the same mass of cashmere as the cashmere, and the Cashmere Genuine Index (CGI) is calculated using formula (3).

number

number

Advantages of the Invention

[0012] According to the present invention, there is provided a method for discriminating recycled cashmere that can evaluate recycled cashmere from physical and chemical aspects. The method for discriminating recycled cashmere according to the present invention can evaluate recycled cashmere more objectively than in the prior art, and thus is effectively used for the management of animal hair fibers.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, "recycled cashmere" refers to fibers that have been spun, woven, knitted or processed into felted form and then returned to yarn or fibrous form without being used by the end consumer, or fibers that have been spun, woven, knitted or processed into felted form, used by the end consumer, and then returned to yarn or fibrous form.

[0014] Hereinafter, "new wool cashmere" refers to unused cashmere that has never been used for processing or manufacturing, or fibers that have been spun, woven, knitted or processed into felted form and have not been processed to be returned to yarn or fibrous form. Since it has not been subjected to processing or manufacturing or has not undergone a fiber recycling process, new wool cashmere usually has not suffered physical or chemical damage. However, since cashmere is an animal hair fiber, although the proportion is low, damage (crushing, tearing or splitting) to the fiber shape may be seen in a part of the new wool cashmere.

[0015] Hereinafter, simply "cashmere" is a concept including both the above-mentioned recycled cashmere and new wool cashmere, and means the general term for cashmere.

[0016] The method for identifying regenerated cashmere according to the present invention is characterized by using a model equation obtained from multivariate analysis, in which at least the percentage of cashmere showing damage (K1) determined by the microscopic method specified below and the CGI (K2) determined by the animal hair peptide analysis specified below are used as explanatory variables, and the dependent variable is T (where T is a real number excluding 0) for new cashmere and -T for regenerated cashmere, to determine whether the cashmere to be identified is regenerated cashmere or not. In this invention, by integrating the physical and chemical effects inherent in regenerated cashmere as processing or manufacturing history and utilizing statistical processing, it is possible to accurately distinguish between regenerated cashmere and new cashmere. Furthermore, by introducing statistical processing, regenerated cashmere can be identified efficiently and objectively.

[0017] Multivariate analysis is used for statistical processing. Examples of multivariate analysis include multiple regression analysis, simple regression analysis, logistic regression analysis, and Cox proportional hazards regression analysis. Among these, multiple regression analysis is preferred from the viewpoint of the accuracy of the multiple explanatory variables and the resulting dependent variable.

[0018] The explanatory variables include at least the percentage of cashmere showing damage (K1) determined by microscopy and CGI (K2) determined by animal hair peptide analysis. The percentage of cashmere showing damage (K1) determined by microscopy is effective in evaluating the inherent physical effects of regenerated cashmere, and CGI (K2) determined by animal hair peptide analysis is effective in evaluating the inherent chemical effects of regenerated cashmere. When performing multivariate analysis, it is possible to introduce explanatory variables other than the two types mentioned above, but it is preferable that the explanatory variables be the percentage of cashmere showing damage (K1) and CGI (K2) determined by animal hair peptide analysis, because it allows for the direct evaluation of the inherent physical and chemical effects of regenerated cashmere.

[0019] Microscopy is the method described below. <Microscopy> Cashmere is identified using optical microscopy according to JIS L 1030-2 7.7.1 at a magnification of 100x to 500x. The shape of the cashmere fibers is identified and they are distinguished into "normal cashmere" and "cashmere with damage to its shape (crushed, torn, or frayed)." Identification and distinction are carried out sequentially until the total number of fibers reaches 1000 or more. The percentage of "cashmere with damage" is calculated using formula (1). Percentage of cashmere showing damage (%) = Total number of cashmere showing damage (pieces) / Total number of cashmere measured (pieces) × 100 … (1)

[0020] In microscopy, "cashmere with structural damage" refers to cashmere that is crushed, torn, or frayed, while "normal cashmere" refers to cashmere in the sample other than the aforementioned "cashmere with structural damage."

[0021] The animal hair peptide method is as follows: <Animal Hair Peptide Method> Animal hair peptide analysis of cashmere-containing samples is performed in accordance with ISO 20418-2 Peptide detection using MALDI-TOF MS. If the sample contains wool, the Cashmere Genuine Index (CGI) is calculated using formula (2). If the sample does not contain wool, the animal hair peptide analysis is performed on a sample mixed with the same mass of cashmere as the cashmere, and the Cashmere Genuine Index (CGI) is calculated using formula (3).

number

number

[0022] In animal hair peptide analysis, the peak ratio of chemically damaged regenerated cashmere tends to be lower than that of new cashmere. This characteristic can be used to determine the CGI (Chemical Growth Index). To improve the accuracy of the CGI, measurements are performed separately for samples containing wool (i.e., samples containing at least two types of mixed fibers, including cashmere and wool) and samples that do not contain wool.

[0023] If the sample contains wool, the CGI is calculated using the following procedure. 1) First, determine the percentage of cashmere in the sample, X(%), of the total 100% by mass of cashmere and wool. The percentage of cashmere X(%) can be determined, for example, according to the optical microscopy method specified in JIS L 1030-2 7.7.1. 2) Next, the animal hair peptide analysis of the sample is performed in accordance with ISO 20418-2 Peptide detection using MALDI-TOF MS. The cashmere peak ratio obtained here is P ca (%) 3) The CGI is determined using equation (2). As an example, consider a sample consisting of 50% cashmere by mass and 50% wool by mass. The cashmere blending ratio X = 50%, and the cashmere peak ratio P obtained by animal hair peptide analysis. ca If we set it to =30%, then from equation (2), we can find that CGI ≈ 0.429.

[0024] If the sample does not contain wool, the CGI is calculated using the following procedure. 1) First, since the sample does not contain wool, the percentage of cashmere in a total of 100% by mass of cashmere and wool is determined to be X = 100%. 2) Next, the sample is mixed with wool of the same mass as cashmere. Following ISO 20418-2 Peptide detection using MALDI-TOF MS, the animal hair peptide analysis of the sample after wool mixing is performed. The cashmere peak ratio obtained here is P w+ (%) 3) The CGI is calculated using equation (3). As an example, consider a sample consisting of 100% cashmere by mass. The cashmere blending rate X = 100%, and the cashmere peak ratio P obtained by animal hair peptide analysis. w+ Let's assume it's 30%. Since the mass of the added wool is equal to the amount of cashmere, W' = 100%. From equation (3), we can find that CGI(A) ≈ 0.429.

[0025] When deriving the model equation using multivariate analysis, the dependent variable is set to T (where T is a real number excluding 0) for virgin cashmere and -T for recycled cashmere. T is not particularly limited, but is preferably an integer between -10 and -1 or between 1 and 10, more preferably an integer between -5 and -1 or between 1 and 5, and even more preferably an integer between -3 and -1 or between 1 and 3. Note that setting the dependent variable to -T for recycled cashmere means, for example, setting the dependent variable for recycled cashmere to -1 when the dependent variable for virgin cashmere is 1, or setting the dependent variable for recycled cashmere to 1 when the dependent variable for virgin cashmere is -1.

[0026] The model equation obtained from multivariate analysis is used to determine whether the cashmere being classified is reclaimed cashmere or not. Since the dependent variable is T for new cashmere and -T for reclaimed cashmere, when determining whether the cashmere being classified is reclaimed cashmere, if the result obtained from the model equation has the same sign as -T, it can be determined to be reclaimed cashmere. Similarly, if the result obtained from the model equation has the same sign as T, it can be determined to be new cashmere. Note that "same sign as T" means positive if T is a positive real number, and negative if T is a negative real number. Also, "same sign as -T" means negative if T is a positive real number, and positive if T is a negative real number.

[0027] When the multivariate analysis is multiple regression analysis, and the explanatory variables are the percentage of cashmere showing damage (K1) and CGI obtained by animal hair peptide analysis (K2), the resulting model equation can be expressed, for example, as equation (A). y = a + b1x1 + b2x2 (A) In formula (A), a: A real number between -10 and 10 (inclusive). b1: A real number with the same sign as -a, and whose absolute value is greater than 0 and less than or equal to 30. b2: A real number with the same sign as a, and whose absolute value is greater than 0 and less than or equal to 30. x1: Percentage of cashmere showing damage as determined by microscopic examination (%), K1 x2: CGI (K2) required for animal hair peptide analysis

[0028] a is preferably a real number between -6 and 6, and more preferably a real number between -3 and 3. b1 is a real number with the same sign as -a, and its absolute value is preferably greater than 0 and less than or equal to 25, more preferably greater than 0 and less than or equal to 20. b2 is a real number with the same sign as a, and its absolute value is preferably greater than 0 and less than or equal to 25, more preferably greater than 0 and less than or equal to 20. Note that "same sign as a" means positive if a is a positive real number, and negative if a is a negative real number. Also, "same sign as -a" means negative if a is a positive real number, and positive if a is a negative real number. However, when a is 0, b1 and b2 may have the same sign or different signs.

[0029] There are no particular restrictions on the number of samples required to calculate the model formula, but it is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more. There is no particular upper limit, but it is preferably 1000 or less, more preferably 500 or less, and even more preferably 100 or less.

[0030] The method for identifying recycled cashmere according to the present invention can be used to identify any sample containing cashmere, even if it is a mixed sample containing cashmere and other fibers. The sample may contain fibers other than cashmere, as long as it contains cashmere. Examples of fibers other than cashmere include animal hair fibers such as wool, yak, and alpaca; animal fibers such as silk; plant fibers such as cotton and linen; synthetic fibers such as polyester fibers (e.g., polyethylene terephthalate fiber, polybutylene terephthalate fiber, etc.), polyamide fibers (e.g., nylon 6, nylon 66, etc.), and acrylic fibers (e.g., polyacrylonitrile fiber, etc.).

[0031] Fibers identified as recycled cashmere can be processed through spinning, bleaching, and redyeing, and then knitted and sewn to be distributed to the market as recycled cashmere products. Since the use of recycled cashmere contributes to reducing environmental impact and clothing waste, this invention is extremely useful in realizing a sustainable society. [Examples]

[0032] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by the following examples, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In the following, unless otherwise specified, "parts" means "parts by mass" and "%" means "percent mass".

[0033] Samples of new wool cashmere (No. 1 to No. 12) and regenerated cashmere (No. 13 to No. 24) were prepared, and a model equation was obtained using multiple regression analysis with these samples. All new wool cashmere samples included unused cashmere or cashmere that had been processed into fabric (raw material, finished product, etc.) but had not undergone any treatment to return it to yarn or fibers. On the other hand, the regenerated cashmere samples included cashmere that had been processed into fabric at least once and then treated to return it to yarn or fibers. The percentage of cashmere showing damage as determined by the above microscopic method (K1) and the CGI (K2) determined by the above animal hair peptide analysis are summarized in Table 1.

[0034] Next, for the new cashmere samples No. 1 to No. 12, the dependent variable was set to T=1, and for the regenerated cashmere samples No. 13 to No. 24, the dependent variable was set to -T=-1. Based on these conditions, we derived the model equation, which is equation (A-1). y=0.2242-1.2315x1+1.4747x2(A-1)

[0035] Furthermore, when the values ​​obtained from the new cashmere samples No. 1 to No. 12 and the regenerated cashmere samples No. 13 to No. 24 were verified using formula (A-1), the results are shown in Table 1. As shown in Table 1, for the regenerated cashmere samples No. 13 to No. 24, formula (A-1) was calculated as a negative real number (i.e., the same sign as -T), while for the new cashmere samples No. 1 to No. 12, formula (A-1) was calculated as a positive real number (i.e., the same sign as T). In other words, the method for identifying regenerated cashmere according to the present invention evaluates regenerated cashmere from physical and chemical aspects, and therefore allows for a more objective evaluation of regenerated cashmere compared to conventional methods.

[0036] [Table 1]

Claims

1. At a minimum, the percentage of cashmere showing damage as determined by the microscopic method specified below (K 1 ) and CGI (K) obtained by the animal hair peptide analysis specified below. 2 This method uses a model equation obtained from multivariate analysis, with the following variables as explanatory variables and the dependent variable being T (where T is a real number other than 0) for new cashmere and -T for reclaimed cashmere, to determine whether the cashmere being classified is reclaimed cashmere or not. <Microscopy> Cashmere is identified using optical microscopy according to JIS L 1030-2 7.7.1 at a magnification of 100x to 500x. The shape of the cashmere fibers is identified and they are distinguished into "normal cashmere" and "cashmere with damage to its shape (crushed, torn, or frayed)." Identification and distinction are carried out sequentially until the total number of fibers reaches 1000 or more. The percentage of "cashmere with damage" is calculated using formula (1). Percentage of cashmere showing damage (%) = Total number of cashmere showing damage (pieces) / Total number of cashmere measured (pieces) × 100 ... (1) <Animal Hair Peptide Method> Animal hair peptide analysis of cashmere-containing samples is performed in accordance with ISO 20418-2 Peptide detection using MALDI-TOF MS. If the sample contains wool, the Cashmere Genuine Index (CGI) is calculated using formula (2). If the sample does not contain wool, the animal hair peptide analysis is performed on a sample mixed with the same mass of cashmere as the cashmere, and the Cashmere Genuine Index (CGI) is calculated using formula (3). [Math 1] [Math 2] In formulas (2) to (3), P ca Cashmere peak ratio (%) determined from animal hair peptide analysis P w+ Cashmere peak ratio (%) determined from animal hair peptide analysis after wool addition. X: Cashmere content (by mass) in the total 100% by mass of cashmere and wool in the sample. A: Cashmere Genuine Index (CGI) W': Mass ratio of added wool to cashmere (%)

2. The method for determining whether or not the cashmere to be determined is recycled cashmere, wherein if the result obtained from the model formula has the same sign as -T, it is determined to be recycled cashmere.

3. The method for determining whether a product is recycled cashmere, according to claim 1 or 2, wherein the recycled cashmere refers to a fiber that has been spun, woven, knitted or felted, and then returned to yarn or fiber form without being used by the end consumer, or a fiber that has been spun, woven, knitted or felted, and then returned to yarn or fiber form after being used by the end consumer.

4. The discrimination method according to claim 1 or 2, wherein the multivariate analysis is multiple regression analysis.

5. The explanatory variable is the percentage of cashmere (K) in which the damage is observed. 1 ) and CGI(K) obtained by the animal hair peptide analysis. 2 The method for determining the two types of the method described in claim 1 or 2.

6. The determination method according to claim 1 or 2, wherein the aforementioned model formula is represented by formula (A). y=a+b 1 x 1 +b 2 x 2 (A) In formula (A), a: A real number between -10 and 10 (inclusive). b 1 : A real number with the same sign as -a, and whose absolute value is greater than 0 and less than or equal to 30. b 2 : A real number with the same sign as a, and whose absolute value is greater than 0 and less than or equal to 30. x 1 : Percentage of cashmere showing damage as determined by microscopic examination (%), K 1 ) x 2 CGI (K) required for animal hair peptide analysis 2 )

Images